Ford Focus steering oscillation at low speeds

Question: Yesterday I bumped my left wheel on a pavement, due to an understeering after accelerating (my bad). I smashed it quite good and I was certain the alignment was off, so I did some tests. No tire squeeking on turns, no high speed vibration, although I noticed the car goes just a little to the left when driving straight. But the most intriguing thing is the fact, when I steer a little (about 2-3cm) from the straight position of the wheel, at low speeds (like 20-40km/h) I can feel a broad and heavy oscillation in my hands, about 1-3hz? I play with the wheel when going straight, tilting it a bit to the left and right, and always feel this oscillation. This behaviour seems to stop over 70-80km/h. What could this be?
Comment: What make/year/model of car? I'm thinking you might have damaged a wheel bearing.
Comment: Ford Focus Trend 2003, Zetec 16v, 5 door, hatchback.
Answer: You would best be advised not to drive the vehicle before you have had it inspected for any damage by a mechanic or tyre centre. Your reported observation on the change you have noticed only goes to show that something is damaged, and it may be a case of it about to completely break. Have it inspected.
Comment: I appreciate your concern, I moved it only for the purpose of testing it, on an empty road, to check if something was going wrong.
Answer: Check the tire for play.

Secure the car on a jackstand near the corner you want to check.
Grab the tire on the left and right and alternate pushing/pulling.
Do the same top to bottom.

Top to bottom is usually ball-joint. Left to right is sometimes tie rod and sometimes wheel bearing. The important thing is that if there's play, something is wrong and needs further inspection.
Answer: I have a similar symptom on my car when the suspension bottom ball joints wear out: at some speeds, when turning just slightly, wheel wobble ensues, and I can feel it through the steering wheel. Sometimes it's quite pronounced.
This happens quite often because my car is 40 years old (Triumph Stag) but has similar front suspension to modern cars. It just wears a bit more quickly.
What happens is as the bottom ball joint of the suspension strut wears, it allows play which allows the wheel to 'castor' a little bit, but the nature of the geometry is such that it ends up wobbling from one end of its play to the other. This can only happen when the suspension alignment is fairly relaxed, which for most cars is when slightly turning a corner (owing to various alignments being [deliberately] not quite central).
This also happens if the track rod end joint (end of steering rack) wears, but less so.
Best bet is to have the bottom ball joint & track rod ends (both sides, to be sure) checked, but especially the one you clonked of course. Shouldn't cost much to replace them.


AMPK, PAN-AMPK, western blot

Question: What does it mean by adding PAN before the AMPK. I am trying to do a western blot assay on AMPK and I am confused by PAN-AMPK, AMPK. does it mean pancreases? Is pan-ampk the total ampk?
Comment: Welcome to Biology.SE! Please take the [tour] and then go through the help pages starting with [Ask] questions effectively on this site and [edit] your question accordingly. In particular, you need to be clear — e.g. abbreviations must be defined. We also expect you to do some research on your own and then, informed by what you have learned, ask any questions you still have (ideally with references to reliable sources). See also this sites criteria for ["homework"](https://biology.stackexchange.com/help/homework), which can also apply to questions that aren't assigned as homework. Thanks!
Comment: Can you please give some more background of your research?
Answer: Adenosine monophosphate activated protein kinase or AMPK is not a single protein, but is a trimeric enzyme composed of $\alpha$, $\beta$, and $\gamma$ subunits. There are 2 alpha genes, 2 beta genes, and 3 gamma genes, each coding for closely-related but not identical isoforms. In addition, like most protein kinases (and many other proteins), it is regulated by the phosphorylation and dephosphorylation of some of its residues, most notably Thr172, but at numerous other locations as well.
A "pan-AMPK" antibody will bind all of the AMPK isoforms independently of phosphorylation or other post-translational modification (PTM) state. There are also isoform-specific total AMPK antibodies that just bind the $\alpha2$ subunit, or all 3 $\gamma$ subunits, for example. Finally, there are phospho-specific antibodies to various residues that only bind when the protein is phosphorylated at that site.
Both the pan and isoform-specific antibodies are known as "total" antibodies, as they bind independently of PTMs and will show the total amounts of their target(s) on a Western blot, for example.

Source:
I used to be a Product Scientist for a company that makes antibodies, PTM-specific and total, to AMPK and many other targets.

AMPK, PAN-AMPK, western blot


Difference between Data analytics and Data Analysis

Question: What we are referring to when we say Data analytics and Data analysis?
Answer:
Data analytics is the broad field of using data and tools to make business decisions.
Data analysis, a subset of data analytics, refers to specific actions.

Find more at:

Difference between Data Analytics and Data Analysis
Comparison Table Between Data Analytics and Data Analysis
Answer: Data Analytics involves the tools and resources used for data analysis.
Data Analysis is the work itself of analysing data.
Answer: Data Analysis:

Examines, cleans, transforms and models data to derive insights.
Involves techniques such as descriptive statistics, data visualization, and exploratory data analysis.
A broader term that encompasses the entire process of examining and interpreting data.

Data Analytics:

Uses advanced techniques and tools to analyze large and complex datasets.
Involves methods like machine learning, statistical modeling, and data mining.
Specialized field that focuses on uncovering hidden patterns, correlations, and insights from data.


Does hermeneutics refer to Hebrew text after,translation , or is exegesis and hermenutics always about original text of original language?

Question: I am confused! Biblical text seems to be gloss or whitewash,of original Tora and Tanach text, in some cases! To do a proper study of the scripture at hand,should one convert the text of any bible first, to its original language, in order to get an accurate rendering of the original wording used by the Tora and Tanach author, whom composed the ancient text!
Comment: The original language must be used.
Answer: If you are asking about what the term refers to in the title of this site, this may be helpful. It is from @curiousdannii, one of the moderators here:

The subject of this site is the discipline of Biblical Studies. This
is broader than just pure hermeneutics (often equated with exegesis,
though sometimes subtly distinguished from it), and includes... textual criticism, as well as source criticism, form criticism,
and so on. Many Stack Exchange sites have names which don't perfectly
match their subject matters, but it's not like ours is a misleading
name, as probably about 90% of questions are about exegesis proper.

Given this understanding, in this forum one does not need to deal with the text in its original language, although such knowledge is a very useful too.
Answer: I do not have a scholarly answer! (This might be because I am strictly a layman, trying to study scholarly material, as best I can, without the skill set needed to properly do this) My limited answer will be this one despite it not being a good one!
I feel to properly do a Bible Study, one will have to always get back to the original penmanship of the original author (or authors) of any scripture, or narrative examined today, in a faraway land and culture! (This may be hermeneutics and exegesis, in my Layman's terminology) If one does nothing, so to speak, and just accepts the gloss presented as reality in most Biblical Studies as this. Study is referred to by most church groups, one will not have an accurate knowledge about the biblical material one seeks to examine! Until a thorough grammatical, historical review of the ancient text studied is completed, only speculation about the ancient writing can be had! One has to first find out somehow what Hebrew, or Aramaic words the original author penned to parchment or papyrus by lamp light, many years ago!
Comment: Since you have not posted a profile of yourself anyone that may try to help you is at a loss. This site is worldwide and what native language or other languages you may speak could influence the answers you receive. You seem to have a negative opinion of the Bible and the accuracy of the scriptures. If that is the case, I suggest an original  King James Bible and a Strong's Concordance. With the concordance you can look up virtually every word in the Bible and where it appears and then using the Hebrew and Greek dictionaries included, see the original words in the original languages
Comment: You need to know the Strong's Concordance is built to work in conjunction with a King James Bible. There are more than one texts that are referred to as original that are used to translate the various modern translations. Therefore it becomes a matter of faith to believe that God inspired the writing of the original manuscripts as well as protected the subsequent translation. Hermeneutics is a word that is not even in my 40 year old Webster's New World Dictionary. You can Google it and exegesis but it still may be an opinion of this site exactly how to interpret and draw out the meaning .
Comment: I have always thought, and still do, the closer we one can retrieve what was penned, to parchment or similar, by lamplight, with stylus and ink, many centuries ago, the closer we might get to an understanding of what and why the author wrote as he did! Any faith, one might have that all theologians or others will always adhere to this is at best, wishful thinking! I only want faith, in truth claims that have a data set pointing to more possibility for reality than against it! I feel GOD, as in our modern construct and terminology, is forced back onto an ancient narrative about a Hebrew deity!
Comment: Spoken like a philosopher. As you get to my age and see prayers answered and miracles that have no explanation, but yet they were, you begin to learn to appreciate the word. That said, there are always some mysteries in the Word that can be analized and hope to be understood. I try to make it fun.


How to determine the "age" of a linux system since installation?

Question: I thought that I could easily check the timestamp of particular files. Then I realized that it wouldn't be so easy when I saw timestamps like 1991.
Comment: Apparently this is also known as the Ship of Theseus problem; see http://en.wikipedia.org/wiki/Ship_of_Theseus .
Comment: I love all these answers, and have upvoted some, and learned from them.  But it occurs to me that the question isn't well-defined: for instance, my colo'ed box has been through two incarnations of motherboard and four complete changes of HDD in the ten years it's been running, with the FS being dump|restored each time.  All my ssh public keys are dated Feb 19, 2001; but the root FS was created Jun 11 2010, 20:59:01, when the mobo was last upgraded (along with the discs); yet other tests give yet different results, and it occurs to me: how do you define (not discover) the age of a linux system?
Comment: I always have a hdd with a partition that exists since I bought the machine... I put all the stuff I need to back up in there when I buy a new drive or create a new root partition with fresh kernel... But it didn't occur to me :-)
Answer: The simplest way would probably be (presuming sda1 is your /root/):

tune2fs -l /dev/sda1 | grep created

This should show you the date on which the file system was created. Confirmed to work on ext2 to ext4, not sure about other file systems!
Comment: When I get a new drive for my PCs I usually create partitions on it and then `cp -a` data over. So in short: it's not possible to determine the age of the system in all cases.
Comment: Perhaps using `/dev/root` is a bit more general.
Comment: I installed a new system over the previous one, keeping the sda1 FS, and thus the solution of MihaiM below (ssh keys) was more accurate.
Answer: One mechanism I often use is to check the change time (ctime) on files within the root home directory. Since the /root home directory is created at install time, and is often seldom used, this can provide a relatively good approximation.  As clarified by Kyle in the comments, since ctime refers to the inode, and not the data, modifying the file contents will not change the ctime.
By default, the ls command prints the modification time (mtime) of the file.  So if substitute in the ctime option like so,
ls -alct /root

This will print all files, display the create time, and sort by time.
As an example, here is a sample of the 3 oldest files in the /root directory from one of my systems.
ls -alt install.log.syslog .cshrc .tcshrc
-rw-r--r--. 1 root 10238 Feb 18  2010 install.log.syslog
-rw-r--r--. 1 root   129 Dec  3  2004 .tcshrc
-rw-r--r--. 1 root   100 Sep 22  2004 .cshrc

And then by checking the change time
ls -alct install.log.syslog .cshrc .tcshrc
-rw-r--r--. 1 root   100 Feb 18  2010 .cshrc
-rw-r--r--. 1 root 10238 Feb 18  2010 install.log.syslog
-rw-r--r--. 1 root   129 Feb 18  2010 .tcshrc

The date Feb 18th of 2010 certainly tracks with the approximate time I would have first installed that system.
Comment: ctime is actually not the create time of a file, but rather is the change time. This is the last time I change was made to the inode. If you change the permissions or owner of a file this would change. Chances are the owner or permissions of the /root folder itself hasn't changed which is why this is lining up. (I don't know what the c actually stands for -- Single unix specification just has "time_t    st_ctime   Time of last status change".
Comment: Indeed, the date/time of the installer log. Which may or may not be there depending on your distribution / os.
Answer: try
ls -alp /etc/ssh/ssh_host_dsa_key.pub | cut -d " " -f6

the keys are generated when you install the os.
Comment: This is a good idea however some weaknesses have been found in SSH keys and if you've done system updates (and you should be doing system updates!) then the keys would have been regenerated.
Comment: Excellent idea! However, if the key is new enough, `ls` shows the date differently (at least on my machine) so the `cut` command doesn't work right. I would now use `stat -c %y /etc/ssh/ssh_host*pub`. Also, I wonder why file creation times haven't gotten more love on Linux...
Answer: Checking the hardware would be a good bet, if you have access to it.  You could inspect the system and/or hardware components to get a good idea of when it was assembled.
Alternately, if you can gain access to the BIOS screen there's often date info there that can be used to determine how old a machine is.
If you can gain access to the SMART info on the hard drive (smartctl -a /dev/sda) there might be something there to go on.  I don't see a specific timestamp in SMART but there is at least an hours of usage counter. That would provide a lower bound on how old the machine is (since if the hard drive has been running for 100 hours, the system can't be younger than 100 hours).
As for filesystem checks, you could look at the date info for /lost+found - that directory was created when the filesystem was created.   The date on it should agree with the tunefs info from the previous answer.
Comment: on a recent ubuntu system non-admins can't do this, one can however use this:
   stat -c "%z"  /lost+found/
This should give something similar to 2014-05-26 15:14:15.000000000 +0200
Bonus: not locale influenced.
Comment: +1 for the `/lost+found` hint, as this information is available to non-privileged users. Running a batch operation like tune2fs on root filesystems as the superuser is a bit worrysome. In addition, this solution works on FreeBSD and non-ext2/3/4 filesystems.
Answer: With RedHat and derivatives, it's pretty easy to get a general idea of the OS version/vintage through a combination of file age and other system files. I'll usually check the /root/anaconda-ks.cfg file, as it contains the initial server setup and package parameters. Sometimes uname -a will have good information about the kernel build date. There would also be a cluster of files with the same date in /etc; typically the rcx.d links, rc scripts, inittab, etc.
Answer: This also works for Red Hat systems:
rpm -qi basesystem | grep "Install Date"

Comment: Note that this (and the tune2fs trick) works less well with virtual machines, if they're being spun up from a common image.  The check of the ssh host keys is accurate on my Linode, though.
Answer: On an openSUSE system I checked the creation (aka birth) date of /var/log/wtmp will not be reset on rotation. It gets created on the first boot after installation. Thus it is likely to to show a time from shortly after the first boot started:
# ls -l --time=creation --time-style\=full-iso /var/log/wtmp
-rw-rw-r-- 1 root utmp 232323 2005-05-23 23:23:23.235000000 +0200 /var/log/wtmp

Not all file systems support creation date, see https://unix.stackexchange.com/a/91200 . It is not the same as ctime (here c for change) from GNU ls. Even if this information exists and can be read, there might have been reasons the date was reset, e.g. human intervention.


What will be the best way to overwrite the core functionality in Magento 2?

Question: It will be great if someone provides me a small example of any core functionality overwrite.
Answer: It depends on what you're trying to do and what scope of effect you want it to have, but generally there are two types of customisation technique which you can use (there are others, but these are the 'best practice' approach):
Plugins
An implementation of the Aspect-Oriented Programming Design Pattern. They basically allow you to modify the behaviour of individual methods in a class. They are defined in XML (as are most things in Magento) and allow you to add/replace/customise the behaviour of individual methods before, during and after the method is executed.
The Magento 2 Dev Docs have a very comprehensive overview of how they work and examples of how to use them:
https://devdocs.magento.com/guides/v2.2/extension-dev-guide/plugins.html
Preferences
This technique allows you to replace one implementation of a class with your own. This is the closest thing Magento 2 has to the Magento 1 style 'class rewrite' feature and, just like when using that feature, defining a Preference will allow you to override an entire class.
Once again, the Magento 2 Dev Docs has comprehensive explanations and examples, so I won't repeat what they've written here:
https://devdocs.magento.com/guides/v2.2/extension-dev-guide/build/di-xml-file.html#abstraction-implementation-mappings
There is also the event/observer system, but I haven't included that above because you only need to observe an event to use them, you don't need to override any part of the core and you specifically mentioned 'core functionality overwrite' in your answer.


How do I make a CiviEvent accessible to the public?

Question: After I create an event in CIVI where does it then go?  How can outsiders find out event?
I participated in a class the other day and was successful at the application but now that I have created the event I am unsure how to find it and how others can find it to register.  Thank you kindly.
Answer: By default CiviCRM events aren't publicised online. To make the event public you need to tick the box for online event registration.
See the user guide for more details: Online event registration


What are some potential problems you can have if you happen to share similar names with an author?

Question: I am a freelance author consultant and have ran into a unique problem. My customer happens to share a similar name with a famous author and she is concerned that there might be potential problems if she publishes under her own name. I would like to know if there is any possibility that she could find herself in legal trouble for using her own name.
Comment: Perhaps they could add an initial? Nobody would ever confuse Iain Banks with Iain M Banks.
Comment: You can always use a pen name.
Answer: As for legal trouble, you should ask the lawyers about that, not the writers. But I doubt she'd get into trouble, per se, since it is, after all, her own name. Though it's possible there is some rule about not using the same author name as another author (I know there can be with actors) and publishers might insist she get a pen name.
That said, even if it is allowed, I would strongly STRONGLY recommend she NOT use her own name if there is an existing author by that name who is well known. Everyone will get her "brand" mixed up with this other author's, making it hard for her to build her own. She's going to want her own unique platform with her own following; the last thing her image, marketing, and titles need is to be constantly confused with someone else's. Tell her to brainstorm a nice pen name (maybe help her do it, or find someone who is knowledgeable about such things to help with it!) It can be similar to her real name, if she wants, but it needs to be different enough it isn't going to get confused for someone else.
Basically, this is probably less an issue of "would I get in trouble?" and more one of "how do I keep my brand separate from this other person's?"
Answer: As @MarielS, it's not a legal issue, but a customer confusion issue. People will confuse her brand for the famous author's brand constantly - in search results, in bookstores, on covers, etc. They may pick up one of her books expecting it to be the work of that other author, only to be disappointed when they realize it's not who they were expecting.
Imagine if my name was Stephen King. Obviously, if I were to publish a book with my name on the front cover, people would think, "Oh, wow, Stephen King must have a new book out!" But then they discover that I'm actually a small-time science fiction writer, not a horror writer, and they will probably put my book down and feel pretty darn cheated. So I would probably either publish under a shortened name (Stephen K. or S. King, perhaps) or just change it altogether and use a pen name.
Answer: One potential problem is getting sued.  Anybody can sue anybody for anything.
Getting confused with the other author should someone try to find her work.
Not being able to build a unique brand if she writes more books.
Answer: I don't know much about laws on that, but you shouldn't get into any trouble just for sharing someone's name. Honestly, what can you do about it? You can't do anything about it.


How do I install this Gnome theme?

Question: I can't seem to find the answer to this...  I downloaded a theme http://gnome-look.org/content/show.php/Glassy+Matrix?content=51232. But it doesn't see, to have a file extension, and its a bin file.  When I try to open it, error message says that the file is an unknown file type.  How do I install this theme?
Answer: Downloaded file is a .emerald file.
To install .emerald file you need to install the package emerald.
1). Install the package emerald. It can be installed with the ppa:nilarimogard/webupd8 PPA.
sudo add-apt-repository ppa:nilarimogard/webupd8
sudo apt-get update
sudo apt-get install emerald

2). Open the Emerald Theme Manager.
You can install the downloaded .emerald file with Emerald Theme Manager.

Go to preferences.
select Manage new Theme.
Select Import. Then select the downloaded file.

3). Start your theme.
You can start the emerald theme by the command :
emerald --replace

Comment: I'm still having issues.  I installed emerald. I ran that command in the terminal & it didnt do anything.I tried looking online and found out that im supposed to used it with compiz mnger.I followed steps here: http://www.noobslab.com/2014/02/emerald-decorator-and-themes-available.html  when I enabled "windows decorations" I get a warning stating that unity can do the same thing, or something along those lines.  When I click to proceed, unity completly went away, I had no options, just a blanks screen.  I had to reinstall ubuntu.  Does compiz window decorations option not work in ubuntu 14.04?

How do I install this Gnome theme?


If mobile phones have to go through such extensive FCC/CE/EMI testing, why do they interfere with my radio?

Question: It seems that to sell a GSM mobile phone, companies like Apple, Motorola, Sony Ericsson and many others invest a considerable amount of money in EMI testing them. Yet they still interfere with my stereo, radio, computer speakers, and other devices. Why?
Answer: The interference caused by GSM phones is an intentional radiator that is within the required limits of regulations.
I tend to blame the other devices for not shielding well enough. Any wireless device is going to have harmonics, its just a way of life and it just so happens that one of the harmonics with many GSM devices is in an audible range.
Comment: GSM is based on time division multiplexing, which means that the power envelope is not constant. The RF is pulsing on and off at audio frequencies. This pulsing is what you hear when the phone interferes with something. I think Kellenjb meant to say "frequency components" and not necessarily harmonics
Comment: ".. one of the harmonics with many GSM devices is in an audible range." -- sounds a bit strange. Could you clarify?
Comment: Interferes with the freq. in the radio perhaps?
Answer: Take a close look at a typical FCC declaration of conformity:
"This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:
(1) This device may not cause harmful interference, and
(2) This device must accept any interference received, including interference that may cause undesired operation."
The key word is harmful. Distortion or buzzing on speakers is not considered harmful. Annoying, yes, but not harmful.
Comment: Another key word is "undesired operation".  The speakers are not designed to accept the interference they're receiving without undesired operation.
Answer: Consumer goods like radios, stereos, etc. are built down to a price and typically have very poor immunity to out of band signals from devices like mobile phones. You could modify your equipment with filters, better quality mixers, and so on, but it will be expensive and a lot of work. Military equipment has to operate in close proximity to high-power signals, and a lot of attention is paid to screening and filtering, as well as circuit design, to avoid such problems, which is one reason why it is so expensive.
Comment: The cell phone causes this noise in the first place because it is designed to be an RF transmitter with high modulated/pulsed RF power output. It's a fact of life that this will be demodulated by analogue electronics, and if the modulation is in the audio range, it will be noticable on audio equipment.
Comment: Am I missing something in his question? It seems to me that he is asking about why his cell phone causes that noise in the first place. Having everyone else answer differently is making me wonder if I have miss read the question.
Comment: That was the question I answered - the problem with the noise he is picking up is caused by the poor design of consumer equipment, and is nothing to do with the phone.
Answer: At least in Europe, although the EMC directive does not have a frequency limit, and the specifications often start by saying they cover d.c. to 400 GHz, in practice limits were only given up to 1 GHz.
I believe this was because it was deemed unlikely that any device would efficiently emit much unintentionally beyond this frequency, but that was all written before 2.4 GHz became so widely used (Wifi, Bluetooth, Zigbee etc). Therefore the audio kit wasn't tested for immunity beyond 1 GHz. In any case, it is usual to accept temporary deviations in analogue equipment, or any equipment, which self corrects with no intervention from the user. Otherwise you have the problem, in analogue equipment of deciding what level of noise is acceptable during an interference event.
Answer: It's worthwhile to note that a lot of audio equipment assumes that signals going into it will consist of audio frequencies, and thus that they do not have to worry about higher-frequency signals.  Unfortunately, if the signals going into an amplifier cause distortion at any stage of the process, such distortion can generate unwanted frequencies from any combination of the input frequencies that happen to be present.  Something like a crystal radio set can exploit this phenomenon; a 900Khz AM carrier modulated at e.g. 1000Hz will have frequency components at 900.5Khz, 900Khz, and 899.5Khz.  Putting the signal through a diode will distort it in such a way as to generate 0Hz (DC), 500Hz, and 1KHz components (though hopefully the two sources of 500Hz components will cancel).  The 1Khz component may then be used to drive an earpiece.
Unfortunately, it's easy for an amplifier input and output stages to exhibit such distortion effects in response to high-frequency signals.  It is curious that such signals can become clearly audible even when they're just crudely coupled to relatively low-impedance audio cables, but it's worth noting that it's possible for the distance between a cell phone and an audio system to be a tiny fraction of its distance to the tower; consequently, a nearby audio device may pick up a signal that's a million times as strong as the one picked up by the tower.
Answer: The other answers here are mainly on track, but one aspect they haven't mentioned is proximity. When I hear interference from a GSM device, it's usually when someone is standing within 2-3 feet of a land-line telephone or telephone-related device (my home answering machine and the conference phones at my office are the main victims I've noticed).
However, the radiated emission limits (both FCC and CE) are based on limiting the emissions from the radiator at a distance of 10 m or more. This means the regulations are not designed so much to ensure that two devices sitting right next to each other won't interfere, but to sure that your phone doesn't interfere with a device in the next room, or in your neighbor's house.
In part, the specification at 10 m distance is simply meant to ensure a uniform test condition, because it gives a reasonable distance for "near-field" radiation effects to have fallen off and ensure the measured radiation pattern will be consistent with the interference effects at any distance in the far field.
But also, the regulations were developed in consultation with electronics manufacturers and they would have considered that trying to reduce radiation to a level where they won't interfere with each other at 0-1 m distance would increase costs (as alluded to in Leon's answer) to a point that would make many consumer electronic products unsaleable.
Answer: Short answer: because your radio didn't go through all that testing.
Comment: Possible, but not likely. I heard it in *lots* of audio apparatuses, including professional broadcast equipment.


Device with OS3.0 not being detected after Xcode upgrade to 3.2.3 with OS4.0 SDK

Question: I have recently upgraded XCode to 3.2.3 with 0S4.0 SDK. Now, after upgrading the setup, one of my device is not being detected by XCode.
In the Organizer window, the device is displayed with a yellow status and XCode complains of "The version of iPhone OS on "" is too old for use with this version of the iPhone SDK. Please restore the device to a version of the OS listed below."
OS installed on device : 3.0 (7A341)
XCode Supported iPhone OS Versions: 4.0.1, 4.0, 3.2.1(7B405), 3.2, 3.1.3, 3.1.2, 3.1.1, 3.1, 3.0.1, 3.0.
My question is that if the XCode supports 3.0 version, then why the device is not being detected by the IDE.
Answer: try restarting your mac os and power off and on your iphone


Staying secure for every day users: What recommendations do security experts have for wallet management, safety, maintenance?

Question:
What's the safest way to store BIP39 seed words?
What hardware wallet backup options exist?
How can I share details on wallet maintenance with family?
Comment: I voted to close not because this is a recommendations question, but because it's 3 questions instead of 1 question. If you have 3 questions, it's generally better to ask in 3 separate posts rather than all in 1, because we cannot vote on the answers properly (I might want to upvote someone's answer to 1 but not their answer to 2, and this is better done if you ask separate questions). **I'll retract my close vote if you correct this.** Also: I was not the one that initiated the close voting.
Comment: 1. Wheater using hardware wallet, which is the safets one, or paper wallet, you must make sure to write down and keep the seed in more than one secure location. Just think of it as a key to your safe box. Do not share it with anyone.
Answer: Some specific answers to your questions.

I don't know that there is a great answer to this. Your options range from putting it on paper and in a safe deposit box in a bank, to storing it one word at a time in random places (like an escape room scenario). There are some very cool physical devices for storing seed words that are made if metal to be fire resistant. Basically you use a punch to mark the seed words in the metal.

Hardware wallet backups are similar. You just have a list of seed words that you need to protect. One nice thing about Hardware wallets is that you can restore a second or third wallet with the same seed phrase and store them in separate locations.

This depends on your family and estate management scenario. Do you trust your family? It can be a good idea for you to share the details of your wallet with a spouse or parent that can manager your funds if you are incapacitated. You can also have safe-deposit box ownership be transferrable to someone should you become incapacitated and inside have instructions for them on how to manage your funds (a will helps here).

Some more thoughts...
Wallet safety, as any other cyber security question, comes down to risk vs. effort. That is, how much is what you are trying to protect worth and how much effort and expense are you willing to put it to protect it? The billions of dollars in Bitcoin on the Tesla balance sheet is managed much differently that my grandpa's $100 of crypto.
This is of course up to the individual, but something like below is what I tell people.

< $100 worth
Standard software wallet with seed phrase in a password manager shared with a family member is probably fine.
In between is kind of a grey area.
> $1000
This should definitely be on a hardware wallet if possible. Family members can share the PIN/passphrase (ex. in case of emergency who can access your funds?). The seed phrase (hardware wallet backup) should be stored off of a computer! You can store the seed in multiple places such as a home safe or bank safe deposit box if available (again your level of risk will help determine this). It's also probably a good idea to leave instructions for family.
~$1M I probably wouldn't want these seed words stored in my house...


What Devices Support USB OTG And How Can Support Be Determined

Question: How do you determine if a given Windows Phone running Windows Phone 10 supports USB OTG? I am aware that only a subset of phones support the protocol, but I haven't been able to find a list of which devices this includes or which specific features determine this support.
Answer: Most phones support USB OTG and I'm pretty sure every phone released in the last 2-3 years support USB OTG.
The easiest way to determine whether a phone supports it or not is to simply try it out and see for yourself. Buy yourself an OTG connector and plug it into the phone and then test it out to see if it supports it.
Answer: Microsoft windows 535 and later windows mobiles does not support USB OTG DATA TRANSFERING.so it is not an idea to transfer data using OTG CONNECTOR.


Resources for taking an existing design template and putting it into a masterpage?

Question: I am not a designer, so I took a design template from http://www.opendesigns.org/ and was successful in implementing the design in one page, but when I tried to put it into a masterpage, it came out funny looking, so I was curious if there were any resources/tutorials on taking design templates and putting them in masterpages.
Answer: A master page is just HTML / ASP with a placeholder for the content.
As long as everything is well-formed, it should display as normal.
When I am building a master page, I build my design, then copy and paste into the master page and insert the placeholder where I need it.
Comment: Does your design go inside the content place holders or do the content place holders go inside the design?
Comment: The content placeholders would go in the designs, where you want the content to appear - usually you'd have something like a header area for the page title, the main body copy area, and a footer element for any custom footer components.
Answer: some of what you say is quite confusing, i think you need to be clearer. A master page is a template for layout on your site or subsite, you would never serve a master page as content, you would always use the master page as a basis for a content page, the master page allows you to define a set of placeholders and, in principle, a global definition of the skeleton of your pages, for the area within which the master page will be used. Its usual to place site wide (or sub site wide - depends what you are doing) content onto the master page itself, things like menus, banners etc. And then let the pages that use the master page define what is held in the content placeholders that will be specific to the page instances.
when you say you put the design in a page, was it pure html ? or was it an aspx ? you arent clear on how you got from
1) design template to "page" (please explain html or aspx)
2) how you took your page and "put it in" your master page (i think if you explain, it might be easier to help)


importing .vpl files (vpn tunnels) on mac

Question: Is there any way I can import a .vpl file? This is the only way of connecting I have and for now I can only do it on Windows (with FortiClient 4.x.x) because 5 doesn't support importing .vpl anymore.
Answer: You can use the "FortiClientTools" application in Windows to import your .vpl configuration file. From there, you can export the configuration file to a newer type (4.3/5.0) that can be imported into newer versions of FortiClient. Exported config files that are encrypted will likely have a filename extension of .sconn; unencrypted config files should be appended with .conn.
If you need to import those config files into the newest version (5.2) of FortiClient, you can change the filename extension from .sconn or .conn to the newer format (.sconf; .conf). Once the extension has been changed, you can import that config file under the FortiClient menu -> Preferences -> General -> Restore.


Why do MLB AL teams play against NL during season

Question: NY Yankees play against NY Mets during the season but only since 1997 : https://en.wikipedia.org/wiki/Mets%E2%80%93Yankees_rivalry#1997%E2%80%931999:_Interleague_regular_season_play_begins I was wondering how come an AL team plays against a NL one before they reached the play offs
Comment: I noticed you've asked three very similar questions using three completely different unregistered accounts. Would you consider registering for a full account so you can keep all your questions in one place? You can also ask for the questions you've asked until now to be merged into your new account.
Comment: Is there some reason the wikipedia page doesn't answer your question?
Comment: i saw my basketball question was interesting, so i asked more questions, but it wouldnt let me access those accounts when i asked.
Answer: In the current MLB divisional breakdown, there are 6 divisions of 5 teams each, organized into two leagues of 15.  As a result, interleague play is mandatory in order to finish the schedule in a reasonable timeframe!  Otherwise two teams would always have half of a week off at a time, and you'd have to add a few weeks to the schedule.
This changed in 2013, when the Astros were moved to the American League (remember, in 2005 they were the National League representative in the World Series).  Prior to that, the National League had 16 teams (5 E,6 C,5 W) and the American League had 14 teams (5 E, 5 C, 4 W).  (Conveniently, Houston is barely west of the westernmost AL Central team, Kansas City.)
Interleague Play was officially introduced in 1997, and the reason that it did not exist prior to that was that the American League and the National League formed as different, and competing, leagues (the American League was originally the American Association).  While they would hold a championship each year, prior to the merger they had no incentive to play, and after the merger it became tradition not to (though they considered doing so every so often).  By 1997, though, it was clear that games could be profitable - some teams (such as the Mets-Yankees and Cubs-White Sox) played exhibition games in season against each other, and they were very popular - and, as MLB is a business, they chose to formalize interleague play.


Are representations of $\text{SL}(2,\mathbb{C})$ indexed by one half-integer or two?

Question: I am very confused by this. In Hall's book on Lie theory, he states that the representations of $\text{sl}(2,\mathbb{C})$ are indexed by a half-integer. This is the usual result for $\text{su}(2)$ in non-relativistic quantum mechanics. This is the case since the complexification $\text{su}(2)_\mathbb{C}=\text{sl}(2,\mathbb{C})$. I am guessing then that to find representations of $\text{SU}(2)$ one is interested in exponentiating representations of $\text{su}(2)_\mathbb{C}$. In quantum field theory, however, it is claimed that the representations of $\text{sl}(2,\mathbb{C})$ are indexed by two half-integers. I believe this is because $\text{sl}(2,\mathbb{C})$ is here seen as a real Lie algebra and thus has twice the dimension. How does this relate to us now considering the double cover $\text{SL}(2,\mathbb{C})$ of the orthochronous proper Lorentz group $L_+^\uparrow$ rather than the double cover $\text{SU}(2)$ of the proper rotation group $\text{SO}(3)$?
Answer:
The Lie group $SL(2,\mathbb{C})$, viewed as a complex Lie group, has irreducible representations of complex dimension $2j+1$ classified by a single half-integer $j\in\frac{1}{2}\mathbb{N}_0$.
The Lie group $SL(2,\mathbb{C})$ is the double-cover of the restricted Lorentz group $G:=SO^+(1,3;\mathbb{R})$. The latter is naturally viewed as a real Lie group in physics.
Its complexification $G_{\mathbb{C}}=SO(1,3;\mathbb{C})$ has double cover $SL(2,\mathbb{C})\times SL(2,\mathbb{C})$, whose irreducible representations are classified by two half-integers (since there are now a product of two $SL(2,\mathbb{C})$ groups). See e.g. this & this Phys.SE posts.
A representation of the complexification $G_{\mathbb{C}}$ is also a representation of the restricted Lorentz group $G$. Conversely, any physically relevant representation of $G$ is expected on physical grounds to be a representation of $G_{\mathbb{C}}$ by analyticity.
Comment: Related: https://physics.stackexchange.com/q/93517/2451
Answer: In quantum theory (and thus in the classical field theory which will ultimately be physically relevant through quantization), we are only interested in projective representations of the orthochronous Lorentz group $L_+^\uparrow$ on complex vector spaces. Equivalently, we are interested in the representations of the double cover $\text{SL}(2,\mathbb{C})$. Being a simply connected Lie group, these are in one to one correspondence via the exponential map to the representations of its Lie algebra $\text{sl}(2,\mathbb{C})$. Coming from a Lie group, this Lie algebra is to be regarded as real. We are thus interested in the real linear representations of $\text{sl}(2,\mathbb{C})$. These are on one to one correspondence to the complex linear representations of the complexification $\text{sl}(2,\mathbb{C})_\mathbb{C}$.
Indeed, if one has a real linear representation $\pi:\mathfrak{g}\rightarrow\text{End}(V)$, an extension to the complexification is readily available via $\tilde{\pi}:\mathfrak{g}_\mathbb{C}\rightarrow\text{End}(V):(X_1,X_2)\mapsto\pi(X_1)+i\pi(X_2)$. On the other hand, a complex linear representation $\tilde{\pi}:\mathfrak{g}_\mathbb{C}\rightarrow\text{End}(V)$ induces a real linear one $\pi:\mathfrak{g}\rightarrow\text{End}(V):X\mapsto\tilde{\pi}(X,0)$.


AlwaysOn Multi-Subnet Setup

Question: Without using SAN-to-SAN replication, how does data synchronization occur across subnets in a multi-subnet AlwaysOn (AVG) configuration?  I want to setup a separate VLAN (replica lan) to synchronize data between three nodes (2 sync in DC1, and 1 async in DC2), but concerned there will need to be additional routing resources to make that possible.
Answer: There is no easy answer for this, you will have to go through the entire process from scratch and preferably do it several times so you know exactly what to expect, then focus on monitoring it.  This is well documented though and you should start with a search engine query to get familiar with it.
Edwin is a resident HA expert in the SQL Server community and he has great articles on AG's.  Here is one about your method.  It's too long to post here or shrink, but your answer is to google 'multi subnet ag sql server' or something to that effect.  That will lead you to one of several posts, starting a multi part series by Edwin:
SQL Server 2012 Multi-Subnet Cluster Part 1
Comment: Sorry for not being more clear.  My question is more along the lines of routing the log block traffic and not so much being able to connect to the listeners during failover.  I have Team NIC 1(server network) and Team NIC 2(replica network). Endpoints are bound to replica network, listeners server network.  I want a deeper understanding of how that traffic routes to the second datacenter when the server only has one gateway configured, if that is even possible. Examples I have seen so far either have shown how to configure the replica network, or to configure multisubnet, but not both.  Thanks
Comment: You don't configure routing of anything in availability groups for the network layer. The best you can do is tie it to an IP.  The rest of the work is done by windows and your physical networking configuration. My answer would be: How do normal TCP/IP packets get routed from that network - it'll be routed the same exact way.

AlwaysOn Multi-Subnet Setup


How to create scheduled job that runs every minute in apex salesforce

Question: I am planning to create a scheduled job using scheduled apex in salesforce. I know that we can write and run the job for every one hour. I would like to know if there is a way we can run the code for every minute instead of every one hour.
I know the following code will work fine for every one hour.
System.schedule('Scheduled Job', '0 15 * * * ?', new scheduledJob());

Answer: You can't schedule by the second. The smallest hypothetical schedule you can perform with a single Scheduleable interface is once an hour. if you need a smaller time frame than this, use an external integration, a trigger, or an outbound message (using Workflow Rules)


Is there a way to assign vertex groups to all loose elements via python

Question: I have loose mesh elements within an object and I would like each loos element to be placed in its own vertex group.
Answer: Another take on this. Already had code that separated a mesh into vertex groups from seams,
import bpy

def island_verts(mesh):
    import bmesh
    bpy.ops.object.mode_set(mode='EDIT')
    bpy.ops.mesh.select_all(action='DESELECT')

    bm = bmesh.from_edit_mesh(mesh)
    bm.verts.ensure_lookup_table()
    verts = [v.index for v in bm.verts]

    vgs = []
    while len(verts):
        bm.verts[verts[0]].select = True
        #bpy.ops.mesh.select_linked(delimit={'SEAM'})
        bpy.ops.mesh.select_linked()
        sv = [v.index for v in bm.verts if v.select]
        vgs.append(sv)
        for v in sv:
            bm.verts[v].select = False
            verts.remove(v)
    bm.free() # prob not nec.
    bpy.ops.object.mode_set(mode='OBJECT')
    return vgs

# test run
obj = bpy.context.object
mesh = obj.data
vgs = island_verts(mesh)

for vg in vgs:
    group = obj.vertex_groups.new()
    group.name = "Island"
    group.add(vg, 1.0, 'ADD')

Comment: Thanks for the code. For some reason, though it adds a vertex group for each vertex
Comment: Test the code against the cube (1 vgroup) or suzanne (3 vgroups, the eyes are separate).  Could be something to do with your mesh.  Try using p in edit mode, separate by loose parts, my guess is you will end up with as many objects as vertex groups it added  from running the script.  Probably why it's crashing TLousky's code as well, too many bmesh instances.
Comment: As for some reason, when testing it now, it works. Thank you :)
Comment: I also get separate vert groups for each vertex, with both samples of code. Not sure if there is something that has changed with the API or with BMesh to cause it though.
Comment: Ah, found my problem and the solution is simple: the script actually looks for the object in edit mode to be in vertex select - if it is in edge or face select, that will not work, and you will get a vertgroup for every vertex then. Thank you for the examples, I want to set this as a tool now :D
Answer: Here's a script that iterates over each mesh island and assigns its vertices into a new vertex group.
EDIT - WARNING: After testing it appears that this solution is limited to around 1000 islands (due to Blender's max recursion limit). Use @batFINGER's solution if you have more vertex groups than that.

It's based on a recursive function since the blender API currently doesn't provide (as far as I know) any built in way to get all mesh islands.
import bpy, bmesh

def find_island_and_assign_vgroup( o, remaining ):
    ''' Recursive function that itertaes over mesh islands and assigns a new vertex group to each'''

    if len( remaining ) > 0:
        # Create bmesh object (must do this every time since vertex groups are created in object mode, which destroys the bm object
        bpy.ops.object.mode_set( mode = 'EDIT' )
        bm = bmesh.from_edit_mesh( o.data )
        bm.verts.ensure_lookup_table()

        bpy.ops.mesh.select_all( action = 'DESELECT' )
        bm.verts[ list(remaining)[0] ].select = True
        bm.select_flush( True )
        bpy.ops.mesh.select_linked()

        selected_verts = [ v.index for v in bm.verts if v.select ]

        # Add to a new vertex group
        bpy.ops.object.mode_set( mode = 'OBJECT' )
        vg = o.vertex_groups.new()
        vg.add( selected_verts, 1.0, 'ADD' )

        # Remove this island's verts from the vert list
        now_remaining = remaining - set( selected_verts )

        bm.free()
        find_island_and_assign_vgroup( o, now_remaining )

o         = bpy.data.objects[ bpy.context.object.name ]
all_verts = set( range( len( o.data.vertices ) ) )
find_island_and_assign_vgroup( o, all_verts )

Comment: A bm.free() before the recursive call is probably a good idea, as that's what prob crashes your code on high loose part counts, given the OP's comment on the answers we've provided.
Comment: Thanks for the script. Unfortunately it crashes Blender for some reason.
Comment: Weird, worked for me. Can you upload a blendfile? http://blend-exchange.giantcowfilms.com/
Comment: Makes sense, @batFINGER, will add and test it.
Comment: It doesn't crash now, but actually that's not enough either, as blender sets a maximum recursion depth to ~1000 (stopped in vertex group 992 in the Suzanne X3 test you suggested). So appears like your solution is more robust.
Comment: Thanks, yes it doesn't crash now. @batFINGER's solution appears to calculate a bit faster. Happy there are more than one approaches :)


How does the AIR cache control work, what is the maximum age of cached content?

Question: I'm currently working on a project that needs to request a url multiple times. Having studied the the HTTP Proxy (Charles) it seems that AIR will cache the first response and then return the same response for each subsequent request.
Does anybody know how to know if the response has been cached other than setting the URLRequest to useCache, but this doesn't say if the response was a cached response or not. The digest isn't set on the URLRequest either, although it does mention this is for swz only, so how does it know if the content is the current content or not? Is the responseHeaders used to find out how long to hold the cache i.e.

Cache-Control: max-age=900

Also does anyone know how to flush/purge the cache or are we at the whim of the GC and in that case how does it know if to leave it in the cache or now?
This makes sense to me, but still I would like to know how to regulate this cache.
Further more: I've tested a set up where parallel URLLoaders (10) are made and created which open the same url to see what happens in that instance. It seems that each parallel request is made until a successful response is given, all subsequent calls are then cached. Calls which are sent out before the successful request is then completed. It looks like the items which are already in being processed do not use the cache and return with correct data.
Additional The AIR runtime doesn't even send a "If-Modified-Since" header, so the cache isn't even honoring HTTP protocol. So it seems as if Adobe has implemented it's own version of a cache which doesn't even use HTTP/1.1 Header Field Definitions. Perfect.
Thanks for any help.
Simon
Answer: From the documentation of URLRequest class, it seems that it uses Operating System's HTTP Cache. On a windows 7 OS, it seems that it is using IE's cache.
You can use a HTTP monitor tool like Fiddler, and verify this.
First request is 200, and subsequent requests are 304. After clearing the IE cache. and run the application again, You can see that it results in a HTTP 200 status.


Criticism on truth of Gödel sentence in standard interpretation

Question: Mendelson in his book mentioned the Gödel sentence and argued that in standard interpretation it is true. But Peter Milne in his article (On Godel Sentences and What They Say) criticized: "But we know that we cannot move from consistency of T to truth of γ
when no restriction has been put on the means of representation, the kind
of formulas used". But I cant understand what he means. Can you help me?
Answer: There is no real conflict.
Mendelson is talking about a particular type of Gödel sentence, constructed in a standard way following the pattern of Gödel's original paper. [This is the kind of  sentence people usually have in mind when they speak of a Gödel sentence for a theory $T$, without further qualification -- the sort of sentence constructed to "say", relative to a coding scheme, "I am unprovable in $T$".]
Milne on the other hand is talking about Gödel sentences in a more generic sense which is rather common nowadays, according to which any old fixed points $\gamma$ of the negation of the provability predicate for a theory $T$ counts as a Gödel sentence for the theory [i.e. any $\gamma$ such that $T \vdash \gamma \leftrightarrow \neg\mathsf{Prov}(\ulcorner\gamma\urcorner)$]. If $T$ is consistent but unsound, then the negation of the provability predicate can have false fixed points, so $T$ can have false Gödel sentences in the general sense.
Milne is complaining about people casually moving from a true claim about standardly constructed Gödel sentences (true if the theory is consistent) to false claim about generic Gödel sentences.
This is all explained in my Gödel book (pp. 182-183 of the second edition).
Comment: Thank you for your attention. But my problem has not been resolved, yet. What does Milne mean? "when no restriction has been put on the means of representation, the kind of formulas used". Why restriction must put on?
Comment: Well, there is an issue too about which predicate we use to represent provability -- if Prov(*x*) represents provability so does Prov(*x*) $\land \varphi$, for any old theorem $\varphi$. In unsound theories the junk can be false, and using that provability predicate leads to more complications.
Comment: Ok. But we want to show truth of Godel sentence in standard interpretation. And we should not worry about some interpretations in which provability predicate is false for it. Am I right?
Comment: Example, take the theory PA + $\neg$Con, where Con is the standard consistency sentence for PA. This theory is unsound on the standard interpretation. Milne's observation is that while, still on the standard interpretation, its canonical (standardly generated) Gödel sentence is true, it also has non-canonical Gödel sentences in the general sense of fixed points for $\neg$Prov which aren't true. So saying "Gödel sentences are always true on the standard interpretation" is wrong if you are using (as some writers do) "Gödel sentence" in the wider sense that covers non-canonical cases.
Comment: Ok. I understand it. Thank you very much.


What is the proper way to convert digital picture from the RGB to CMYK so a print-shop can use that file in a color flyer, or magazine, etc?

Question: What is the proper way to convert  a digital picture file, out of a digital camera, from the RGB to  CMYK  so a print-shop can use that file in a color flyer, pamphlet, business card, magazine, etc?
(Not for photo-prints on chemical-sensitive paper)
Comment: Print shops that take digital will have guidelines prepared to cover color spaces, profiles, resolutions and file formats.  I'm unsure if there's a universal best way that would apply to any and all shops.
Answer: There is no "correct" way to do it.  There are many, many different ways and all of them are equally correct.  Are you looking to reduce it to spot color or is it full color printing?  Does the resolution or color depth of their printing process require dithering?  These all matter greatly for proper selection of how to convert the image.
If it is truely full color CMYK printing, it is simply a matter of opening it up in Photoshop and changing the color space to CMYK.  (Under the Image menu if memory serves)  Photoshop will find the nearest match and try to approximate (your display is RGB, so it won't be exact) the final color for you.  You can then make adjustments as necessary to the image before saving it for print.
If it isn't full color CMYK with a comparable color space to your image, then things become considerably more challenging, however without more detail about the process you need there is too much to cover here.


Why Break the Matza of Yitzchak?

Question: The three matzos of the seder are compared to Avraham, Yitzchak, and Yaakov (Maaseh Rokeach Seder Leil Pesach § 58). Why do we specifically break apart the middle matza (ויקח מצה האמצעית ויבצענה לשתים - Shulchan Aruch 473:6) symbolizing symbolizing Yitzchak?
Answer: The following is suggested by Rav Asher Weiss 1 al pi derush:
There's an astounding story described in the gemarra 2, a rendition of a conversation that will take place in the end of days. Hashem will so-to-speak approach our forefather Avraham, and tell him: "Your children have sinned." Avraham, uncharacteristically, will say: "Destroy them!" Hashem will say to Himself: "Avraham never really had a hard time raising kids. Let's ask Yaakov, who struggled with childrearing. Maybe he'll have mercy and pray for his descendants." Hashem will tell Yaakov: "Your children have sinned." Yaakov as well will respond: "Destroy them! They are sinners!" Hashem, will so-to-speak feel frustrated. He'll say: "The old man Avraham doesn't have reasoning, and the young Yaakov doesn't have concern. Let's see what Yitzchak has to say".
Hashem will tell Yitzchak: "Your children have sinned." Yitzchak will respond: "Master of the World, they're my children? Are they not Your children? From the moment they said, 'We will do' before they said, 'We will listen' 3 You called them 'My firstborn son' 4 And now, they're considered my children and not Yours? Further, how much could they really have sinned? How many years does the average person live? Seventy years 5? Take away the first twenty of those years, as a person is not held accountable in Heaven until they're twenty. Of the remaining fifty, half of that is at night, when it's not practical to sin. Of the remaining twenty-five, half of that is spent praying, eating, and relieving oneself." Yitzchak concluded: "All that remains is twelve and a half years to sin. Hashem, if You can bear all of that, then great. If not, I'll bear half myself, so long as You bear the other half. Even if You say that I have to bear all of it, behold, I offered myself to You on an altar.
We see from here that it will only be Yitzchak who will try to defend us in the end of days 6. In his merit, and due to his intervention, the Jews in the future will see Divine mercy and eternal redemption. Yitzchak's winning argument will be that he bear half the Jews' sins, and Hashem bear the other half. Perhaps, to hint to this future dialogue, we specifically break the middle matzah. This middle one is the one that represents Yitzchak. Half of it we keep for the Afikoman. In fact, we take the larger7 half for the Afikoman. Maybe when Hashem and Yitzchak divide up the sins of the Jews, it won't be evenly split. If there were to be one half that is larger than the other, presumably Hashem would take the larger half upon Himself. This is symbolized by the larger half being reserved for the Afikoman, eaten at the end of the seder, which represents the ultimate redemption 8. That is to say, in the merit of our forefather Yitzchak, we will merit the ultimate redemption. May it come speedily in our days.

1 Based on Minchas Asher Sichos Al HaMoadim Pesach s.v. פלגא עלי ופלגא עלך, said over in a shiur on the Arbah Kosos given in 5773 (found in https://www.torahbase.org/four-kosos-5773/ at the end)
[2] Shabbos 89b
[3] Exodus 24:7
[4] Ibid 4:22. This can't be understood literally, as Hashem called them this while they were still in Egypt, and they said נעשה ונשמע after the Exodus. Perhaps since Hashem knew they would say this, they got this title even then
5 Based on Psalms 90:10
6 See Sanhedrin 107a which says all of the forefathers underwent tests, and Emes L'Yaakov to Genesis 27:12 understands that this dialogue will be Yitzchak's test, as it goes against his inherent nature
8 Magen Avraham 473:6 § 21, citing Sefer Maharil Seder HaHaggadah § 21 and Bach ad. loc. s.v. ומ"ש חציה
8 Rav Asher Weiss said this like it was a known idea. I only found it in Derashos Chasam Sofer II p. 306 col. 4 s.v. כתיב, although it probably appears elsewhere
Answer: Like you say, the middle matzah is associated with Yitzchok Avinu.
Kabbalisticly, Yitzchok is associated with the Kav of Gevurah and Judgement. This follows the idea that each of the three Avot correspond to one of the three Kavim. (Avraham to Chesed, Yitzchok to Gevurah and Yaacov to Tiferet)
Part of the Passover seder is related to the idea of Sweetening the Gevurot which is connected with the idea of redemption.
The breaking of the matzah associated with Yitzchok is part of that sweetening process.
This is similar to the idea of how Sarah Imanu's name was Sarai, spelled שרי originally. The letter Yud of her name was split in half into two Heh's. One she kept in her name and the other was added to Avram's name making him Avraham.
This change was done at the Covenant between the halves (Bereshit 15:10-14) which is also the time when G-d told Avraham about the Egyptian exile and the redemption from it.
It was this change that altered their destiny and made possible the conception and birth of Yitzchok Avinu. Redemption is also associated with the process of birth, like when the Jewish people passed through the Red Sea after departing Mitzrayim, similar to passing through the birth canal.
Each of those two halves of the split matzah correspond to our hands and feet which have five digits. The right hand is associated with kindness, which is why general Jewish practice is to begin all actions with our right. The left with Gevurah.
Gevurah is also the idea of division, like the five parts of the mouth which are the source for the pronunciation of the twenty-two different letters of the Aleph-Bet.
Some, including Chabad, also have the additional practice of breaking the larger of those two halves into five pieces which will ultimately serve as the Afikomen.

Why Break the Matza of Yitzchak?


How long can a man stay away from sinful activities?

Question: As we know, men are more eager than female to have sex. Men sexually arouse very quickly. How can he control his desire as his searching for a bride for long time and couldn't get proper (pious,polite etc) bride for him. As women can control themselves for only 4-6 months from any sinful activities.
So, Is there any time limit for men to control his desire.
Comment: You have a lot to learn about women.  Sexually,  they're not much different.
Answer: I think you're asking if a person is addicted to sinful activities like masturbation etc. how long can he stay without repeating it?
First thing I wish to present is this, don't worry Allah will help you, if you strive sincerely,

"Three groups of people Allah obliged Himself to help them: Mujahid in the cause of Allah, a worker to pay his debt, and the one who wants to marry to live a chaste life." (Tirmidhi 1661, Nisai 3120, Ibn e Majah 2518, Ahmed 9637)

Next, you need to stay from triggers which lead you to those activities. In simple sense, you just need to do all those things which addicts do in their rehab course, stay away from triggers, get new experiences.
Where is it written that women can stay only upto 4-6 months? Didn't the wives of Prophets stay chaste for the rest of their lives after Prophet was gone?
Answer: No fixed time limit! How long men or women can control their desires depends on a myriad of factors! From genetics and humoral makeup, to food intake, to surrounding culture, the amount of interaction with opposite sex, mental occupations, etc.
But ideally a Muslim man that has developed some degree of will-power, self-control and psychic strength due to Islamic self-discipline and principled conduct may be able to abstain even indefinitely from sexual activities. I personally know many single religious men and even boys who stay clean for years because of their maximum commitment to Islamic instructions on chastity.
Answer: All Praise to Allah Subhanahu wa Taala and blessings of Him be on Prophet Muhammad peace be upon him His family and companions
Abdullah (b. Mas'ud) (Allah be pleased with him) reported that Allah's Messenger (ﷺ) said to us:
0 young men, those among you who can support a wife should marry, for it restrains eyes (from casting evil glances) and preserves one from immorality; but he who cannot afford It should observe fast for it is a means of controlling the sexual desire.(Sahih Muslim)
One should not delay his marriage when he knows that its becoming difficult for him to control his sexual desires so he could prevent himself from Zina of any kind.With the help of fasting he could control his sexual desires as said by Prophet Muhammad peace be upon him.
Not sure the time limit for men and how you got the calculated time period for controlling desires of women if you could specify this.
Allah swt and His Messenger knows best.


How can I decompile Linux binaries from Windows?

Question: How can I decompile Linux binaries (*.so) from Windows? Thanks.
Answer: You can try Boomerang; you will need to build it first from source as the provided binaries don't cover this case. If you absolutely refuse to compile anything, try the binary distribution for Linux and run it in a virtual Linux machine on Windows.
Comment: I recently *tried* to compile `boomerang`, and I could have started had I littered my box full of includes/headers.  It uses the ML version of the "New Jersey Machine Code Toolkit", plus a good handful of other intense dependencies.  To top it off it looks like the project has not progressed in multiple years.  The best part is this line from the FAQ " ... That means that until this is implemented, then without significant manual guidance, Boomerang can't even decompile its own test/windows/hello.exe"
Comment: The commercial world has plenty of high quality decompilers, it is frankly depressing to see what the FOSS world offers.  To make matters even worse, the freeware decompilers available are barely usable.


Mt. 23:15 - what Jesus is saying "you make him twice as much a child of hell as yourselves!" And what and how "you" (they) did with "him" so?

Question: Text: Mt. 23:15 (NET)
"Woe to you, experts in the law and you Pharisees, hypocrites! You cross land and sea to make one convert, and when you get one, you make him twice as much a child of hell as yourselves!
Comment: Interesting question, Sam! - Thanks for asking for the cultural context to Matthew 23:15.
Comment: Have you looked at Ellicott's helpful comments on this verse?
Comment: Yes, I have read and many others, too. Thanks.
Answer: Many don't realize that the Pharisees were an extermely evangelical sect in Jesus day, and sent out many missionaries all over Rome.  They had special dispensation from Rome to proselytize outside their native province, something not given to other religions (and something Christian missionaries piggy-backed off of, considering themselves jews, to the consternation of the Pharisees who would then report them to local authorities).  Several of the famous rabbis that wrote the Talmud were the children or grandchildren of converts.
But the converts of the pharisees were twice the child of hell because now they were under two laws, the laws of their pagan society and the laws of the pharisees. This is also a parallel to being born again, except you are born twice into sin, and thus twice the son of hell.
Answer: Matthew 23:15 alludes to Jewish converts of Rome who were raised pagan diefying Caesar and later became children (students) of Pharisaic Judaism.
Pharisaic Judaism believed in the Torah but also traditional man-made laws which regarded both the "lack of washing hands before eating" or "tearing grain on the Sabbath" as sins requiring atonement.
Pharisaic laws misinterpreted the Torah. - Yeshua (Jesus) of Nazareth teaches this correction to help Pharisees interpret Deuteronomy 23:26 literally in Mark 2:23-24.
[Devarim 23:26]
"When you enter your neighbor's standing grain, you may pick the ears with your hand - but you shall not lift a sickle upon your neighbor's standing grain."
( כִּ֤י תָבֹא֙ בְּקָמַ֣ת רֵעֶ֔ךָ וְקָֽטַפְתָּ֥ מְלִילֹ֖ת בְּיָדֶ֑ךָ וְחֶרְמֵשׁ֙ לֹ֣א תָנִ֔יף עַ֖ל קָמַ֥ת רֵעֶֽךָ)


How to limit the debug.log file while running bitcoind?

Question: The debug.log file is getting pretty big on bitcoind. How do you limit the size of the file? I'm on Ubuntu 12.
Answer: You can use logrotate.
Create a file named bitcoin-debug in /etc/logrotate.d.
This is the contents:

/home/bitcoin/.bitcoin/debug.log
{
        rotate 36
        monthly
        missingok
        notifempty
        compress
        delaycompress
        sharedscripts
        postrotate
                kill -HUP `cat /home/bitcoin/.bitcoin/bitcoind.pid`
        endscript
}

Replace /home/bitcoin/.bitcoin with the actual path to your bitcoin directory.
The full logrotate manpage is here: http://manpages.ubuntu.com/manpages/jaunty/man8/logrotate.8.html
In ubuntu the logrotate daemon manages many different log files.  In the /etc/logrotate.d folder, each file contains instructions for the logrotate deamon.  Adding this file tells logrotate that you want to start a new log file once a month. The other options tell it to compress the old logs after a day and to keep only 36 months worth (3 years) of logs.
I originally found out about logrotate from this thread: https://bitcointalk.org/index.php?topic=130533.0
Another thing to bear in mind is that given this sends the SIGHUP signal to the bitcoin server, if you happen to be running bitcoin within gdb, it becomes necessary to tell gdb to ignore the SIGHUP signal, so far example, bitcoind can be run using: gdb $HOME/.bitcoin/bitcoin-qt -ex 'handle SIGHUP nostop' -ex run
Comment: i dont get how this works. can you explain. thanks!
Comment: do i need to do anything to kick off the daemon, or does it automatically start doing it?
Comment: logrotate runs by default in ubuntu so you don't need to do anything other than adding files to the /etc/logrotate.d folder.
Answer: Add -shrinkdebuglog to the options you use to start bitcoin, or add shrinkdebuglog=1 to your bitcoin.conf.
Every startup, if the log is larger than 1MB, it will shrink it to 200KB.
Answer: As I don't have enough reputation to add a comment to hsmiths (correct!) answer above:
I found I had to also add a line to tell logrotate to switch users to the bitcoin user (as I run bitcoind as its own user) using the format: su - $user $group. Also as I installed the systemd service  as per the bitcoin github example I had a different PID location. This resulted in the following /etc/logrotate.d/bitcoin-debug file:
/home/bitcoin/.bitcoin/debug.log
{
        rotate 36
        monthly
        missingok
        notifempty
        compress
        delaycompress
        sharedscripts
        postrotate
                kill -HUP `cat /run/bitcoind/bitcoind.pid`
        endscript
        su - bitcoin bitcoin
}

You can restart logrotate with sudo systemctl restart logrotate.service and then check the status for errors with sudo systemctl status logrotate.service
Comment: Comments are not allowed as separated answers even if you don't have enough reputation but an addition to an answer can be posted as an answer - I think.
Answer: Alternatively, you can use printtoconsole to redirect the debug output to the console instead of the debug.log file.


SVD of $H^TXH$ with SVD of $X$ known

Question: let $U D U^T$ be the singular value decomposition of $X \in \mathbb{R}^{d \times d}$, a symmetric positive definite matrix, and let $H \in \mathbb{R}^{d \times n}$ be a rank-$d$ rectangular matrix. Can we say something about the SVD of $H^TXH$ with this information?
Answer: Propably the best thing, you can do, is to calculate the QR-Decomposition of $H$ and evaluate $RXR^T$ to calculate it's SVD ($V\Sigma V^T$). Then you multiply $QV$.
Since $H$ is neither orthogonal nor anything useful, you have scaling and other stuff in there, that will destroy every property of the SVD of $X$.

SVD of $H^TXH$ with SVD of $X$ known


How to prove my Monero balance to the world?

Question: Viewkey allow to disclose incoming txs.  I need to solve a task of making transparent and provable address for our Monero funds. We are investment fund and this feature is mandatory for us.
Comment: Proving balance of an address is different from proving ownership of the address (with Monero, you can't find out an address' balance by looking at a block explorer like in bitcoin)
Answer: This is only feasible with the latest simplewallet from https://github.com/monero-project/bitmonero/, which adds a couple new commands for this (export_key_images and import_key_images).
You, who want to prove balance, need to do a few things:

in simplewallet, run export_key_images key-images

This will save a signed list of key images to the file key-images.

Send the auditor(s) (or make public) your wallet address, the view private key of that wallet, as well as the key-images file you just made.

The auditor then creates a view wallet for your key:
./simplewalet --generate-from-view-key
There will be prompts for address and view key. Then run this command in simplewallet: import_key_images key-images
Include a path to the file if it's not in the current directory.
If all goes well, the view wallet's balance will match the original one.
See Can I fake a balance by giving the view key to an auditor but omitting some transactions and key images? for more information why this cannot be gamed.
Comment: thank you very much for this answer. is it possible to make this view wallet viewable online publicly? or do people have to download it to verify?
Comment: To verify, you have to download the data (which you will have made available online to the public) and check. Someone could make a website which would take a view key and a set of key images and do that check online, but there is none right now to my knowledge.
Comment: so just to be clear--i would offer up my viewkey online as a download?
Comment: Yes. Spam to placate javacsript.
Answer: It is possible with versions newer than 0.10.1. The process is:

Auditor creates the watch wallet, by using your private view key and address.
Using your wallet, command export_key_images to export them to a file.
Send the file to the auditor.
Auditor uses the watch wallet, and commands import_key_images to read them from the file. The watch wallet is now aware of spent status for each output and it shows the correct balance (unless something new was received in the meantime after step 2.)

The proof is interactive. You could, for example, publish the updated key images daily, or only when requested. An auditor would know when to request an update, because having the watch wallet, he could see immediately when you receive something new (which would not be covered with the old set of key images).


Copy paste from Windows (host OS) to Linux Mint in VirtualBox

Question: I'm using Windows 8.1 and I want to copy text from my Windows (host) to Linux Mint in Oracle VirtualBox but I can't. I already picked "Bidirectional" for "drag n drop" and "shared clipboard" in the advanced settings, but I still can't copy and paste.
Comment: Do you have VirtualBox Guest Additions installed on Linux?
Comment: how do i check?
Answer: If you have the contrib repository enabled in Linux Mint, the vbox guest addition may be available there for you to install using apt. That's the best way to be installed.
So, try:
sudo apt install virtualbox-guest-x11 in terminal. If that won't work check your repos for contrib.
I'm not certain if they are available on all versions of Linux Mint, you didn't mention version.
If the package is not there, you should first install some other packages, sudo apt install build-essential dkms linux-headers-$(uname -r) and then follow the advice, in the VM window, click on the Devices menu and select Insert Guest Additions CD Image. Then mount the cd, and execute sudo /{path of mounted cd image}/VBoxLinuxAdditions.run.
I may be missing something on the latter, if you search the net you'll find lots of links.
Comment: Could not mount the media/drive 'C:\Program Files\Oracle\VirtualBox\VBoxGuestAdditions.iso' (VERR_PDM_MEDIA_LOCKED).

Kode Hasil:
E_FAIL (0x80004005)
Komponen:
ConsoleWrap
Antar Muka:
IConsole {872da645-4a9b-1727-bee2-5585105b9eed}
Pemanggil:
IMachine {b2547866-a0a1-4391-8b86-6952d82efaa0}
Comment: Im using linux mint Cinnamon 19.3. i installed the packages.but when i clicked Insert Guest Additions cd image this Error Poped
Comment: Media locked, apparently some other cd/dvd is inserted to VM's virtual cd drive. Vbox tries to eject it; in Linux this is not allowed, it must be unmounted first. To be sure, shutdown the VM, empty any cd from drive (either iso, or virtual drive connected to physical drive) and start it. Then the virtual additions iso should inserted.
Comment: The 1st proposal, `sudo apt install virtualbox-guest-x11` didn't work? If it did, you don't need the rest.


Total derivative in polar coordinates

Question: Let's say I have the function $f$, in polar coordinates, $$(r,\theta) \rightarrow (r^2,\theta)$$ and I want to find its total derivative at some point $(r,\theta)$ (i.e. its best linear approximation). So can I say that this will be the map
$$T(\rho,\phi)=\begin{pmatrix}
2r&0\\0&1
\end{pmatrix}\begin{pmatrix}\rho\\ \phi\end{pmatrix}$$ or should I first find my function in Cartesian coordinates? If so, then what is the correct formula for the total derivative in polar coordinates?
Comment: Well, are your displacements from the point going to be given as differences in the polar or Cartesian coordinates?
Comment: @amd Well since my function is given in polar coordinates lets say the differences are in polar coordinates.
Answer: You were given a function $f:\>{\mathbb R}^2\to{\mathbb R}^2$ by $(r,\theta)\mapsto(r^2,\theta)$, and you have computed the matrix  $$\bigl[df(r,\theta)\bigr]=\left[\matrix{2r&0\cr 0&1\cr}\right]\ ,$$
which is the matrix of the total derivative of $f$ at $(r,\theta)$.
A posteriori you say that $r$ and $\phi$ are in fact polar coordinates in the $(x,y)$-plane, and that you are actually interested in the function $$\hat f:\>{\mathbb R}^2\to{\mathbb R}^2,\qquad (x,y)\mapsto\ (x',y')$$
engendered by the above $f$ relating to polar coordinates in the $(x,y)$-plane. The given $f$ says that the radius $r=\sqrt{x^2+y^2}$ of points $(x,y)$ is squared, while the argument ${\rm arg}(x,y)$ of the points $(x,y)$ is kept by $\hat f$. This geometric description of $\hat f$ says that $\hat f$ is expressed by
$$x'=\sqrt{x^2+y^2}\> x,\qquad y'=\sqrt{x^2+y^2}\>y\ .\tag{1}$$
The Jacobian matrix of $(1)$ with respect to $x$ and $y$ immediately gives you the total derivative of $\hat f$ in terms of $x$ and $y$ – if this is the thing you were actually after.
Comment: Yes I agree with what you wrote. But the question remains: Is the map $T$ that I gave the total derivative or not?

Total derivative in polar coordinates


Can the initramfs image use a compression format other than gzip?

Question: Can the initramfs image be compressed by a method other than gzip, such as lzma?
Answer: Yes. I use in-kernel initrd and it offers at least the following methods:

None (as it is compressed with kernel)
GZip
BZip
LZMA (possibly zen-only)

You can use it on external file and with LZMA (at least on Ubuntu).
Wikipedia states that Linux kernel supports gzip, bzip and lzma (depending, of course, what algorithms are compiled in).
Comment: ok I tried it, it confirmed the kernel can load initramfs with lzma compression, I must compile the kernel using `CONFIG_RD_LZMA=y`. but it will KP if the compression parameter is other than default, for example if i try `lzma -e -9 -z` for initramfs image it will leads to KP.
Comment: does it must be "in-kernel" initrd (and what do you actually means by in-kernel) ? what if I have external file of initrd?
Comment: I would be very surprised if it used different files. As in what it actually means - you can build-in initrd in kernel just as you can build-in modules. I have / on LVM so I need to have initrd script - and the easiest way for me is to build it into kernel.
Comment: sorry but the 'initrd' in this question is actually an initramfs file or a filesystem that initially loaded by kernel, or the file which usually pointed by grub like this `initrd /boot/initramfs-22.214.171.124-85.fc13.i686.img`, maybe I used wrong term (I edited the question)?
Comment: As I stated in edit - yes at least in Ubuntu. I'd be very surprised if it hadn't work. You haven't used the wrong term but I said what 1) I have experience with 2) what I found (that Ubuntu do support it) 3) what I expect. Anyway - why not just try it.
Answer: v4.15 INITRAMFS_COMPRESSION_*
These kernel config options determine if compression is enabled or not.
A quick:
git grep INITRAMFS_COMPRESSION_

on the kernel tree leads to:
usr/Kconfig:134:config INITRAMFS_COMPRESSION_NONE
usr/Kconfig:145:config INITRAMFS_COMPRESSION_GZIP
usr/Kconfig:155:config INITRAMFS_COMPRESSION_BZIP2
usr/Kconfig:168:config INITRAMFS_COMPRESSION_LZMA
usr/Kconfig:181:config INITRAMFS_COMPRESSION_XZ
usr/Kconfig:194:config INITRAMFS_COMPRESSION_LZO
usr/Kconfig:206:config INITRAMFS_COMPRESSION_LZ4

Comment: I believe this is only relevant for a "built in initramfs" (see https://github.com/torvalds/linux/blob/d4e9056daedca3891414fe3c91de3449a5dad0f2/usr/Kconfig#L104). For most uses of initramfs (e.g. at boot time on Debian/Ubuntu) an external file is used. For that way of working, the CONFIG_RD_ options apply
Answer: You can see what compressions are supported for initramfs with:
zgrep CONFIG_RD_ /proc/config.gz
# or
grep CONFIG_RD_ /usr/src/linux/.config

Comment: The initramfs options are apparently called: `INITRAMFS_COMPRESSION_`, I think `CONFIG_RD_` are for initrd?
 https://unix.stackexchange.com/a/429880/32558
Comment: Ohh! Thanks for zgrep! =)


Is it possible to change an amino acid within a protein but not affecting that protein's functions?

Question: In the answer(source - Campbell Essential Biology with Physiology, self-quiz question), it's given that "if the change doesn't affect the protein's shape in any way then it's possible to do so". But practically, is it possible to amend a protein without changing its shape?
Comment: I recommend editing the question to make it more clear, and show your own research on the matter, as per site [policies](https://biology.stackexchange.com/help/homework), then we may guide you. Otherwise, the question may be closed.
Comment: The authors are right saying that one amino acid may be changed without affecting protein's function. It depends on many factors, such as amino acid position and what you change it to. What do you mean by practically? As in vitro? In the title you say 'function' but in the question, you say 'shape' (these are different aspects). What is the exact answer found in the book?
Comment: @danieldelrey I honestly have zero knowledge
I've never studied biology before( as my subjects are maths, electronics, thermodynamics, mechanics and computer science ) but my school is forcing us to and now it's getting really difficult to understand things for me
So I just need it to pass my exam
Comment: Not only can it happen it is one way we study what are the functional components of a a particular protein . https://www.ncbi.nlm.nih.gov/mesh?Db=mesh&Cmd=DetailsSearch&Term=%22Amino+Acid+Substitution%22%5BMeSH+Terms%5D#:~:text=The%20naturally%20occurring%20or%20experimentally,enhance%2C%20or%20eliminate%20protein%20function.
Answer: What the authors are describing here is the idea that function follows from form.  Meaning that a proteins 3D structure is, in many ways, responsible for it's actions.
And yes, it is possible to change a residue without changing the proteins shape.  For example, changing a residue that resides on the outside of the protein from a positively charged one like Lysine to a positively charged one like Arginine (both residues are very similar) will not have any effect on the structure of the protein, in most cases. Same thing when changing an Alanine to a Valine: they are so similar to one another that it would be difficult to find a case where swapping them would cause the protein to change shape or for its function to be destroyed.
Comment: Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer).
Comment: "a proteins 3D structure is, in many ways, responsible for its actions"? in all ways, not in "many"
Comment: @danieldelrey - There are proteins which are intrinsically disordered (https://en.wikipedia.org/wiki/Intrinsically_disordered_proteins) or that contain regions which are intrinsically disordered. In these cases it is the *lack* of a stable 3D structure that is responsible for their action.
Comment: @RiskComplex the discussion is not about stability. All proteins manifest conformational changes (small or large) and/or vibrations that allow them do their function. Their 3D structures (or potential attainable 3D structures, as in IDPs) are still responsible for the specific function e.g. binding to their specific substrate(s) or interacting partners.
Comment: @danieldelrey - When the original poster is asking about a proteins shape or conformation he's referring to a stable structure that persists through time (vibrations and all).  Of course the 3D structure of *anything* physical is responsible to some extent for its function, but that's a useless definition and irrelevant here.
Answer: Although the question is vague, there is value in it.
We have to distinguish shape from function. The function of a protein is mostly (but not only) attributed to certain discrete regions, called domains, which have a particular "shape" attributable to the protein's primary structure (i.e. amino acids) which arrange in a particular 3D spatial conformation (this is the protein's "shape", as explained in your book).
One may change an amino acid (mutate it) within a domain without it losing its shape and function. Such a change should be conservative (e.g. between similar amino acids), but sometimes even an additional carbon atom (e.g. Gly -> Ala) or carbon permutation (e.g. Leu -> Ile) may change a protein's function.
Could you change the protein's shape through a mutation? Certainly. It may or may not lose/affect its function(s). One can even delete entire portions of a protein without it losing its function(s). As John says in the comments, we do this in laboratory  (practically) to see the effects of amino acid changes (mutations).
As I can see, in your textbook, you see this, and here is where the value lies in:

Q: Is it possible to change an amino acid within a protein but not affecting that protein's functions?

A: If the change doesn't affect the protein's shape in any way then it's possible to do so.

I do not have access to your textbook, but the answer there is actually false (or incorrect). Why? Because a protein's shape does not dictate its proper function. We may change its "shape" (3D conformation) of a non-functional domain (or a linker, or an non-important loop) and its function(s) can be wholly preserved.
PS
I do not want to mislead you, but the answer provided there may be useful for beginners in Biology. A beginner's book may not dwelve into such intricancies, so it leaves its reader associate protein shape with its function. Albeit incorrect, it simplifies things by reduction. Nonetheless, it is hardly acceptable to do so.
PPS
Most Biochemistry textbooks cover these aspects through their chapters (e.g. Lehninger's Principles).
This study mentions exactly what I said:

A mutation in the amino acid sequence may alter the structure of a protein but it does not necessarily alter its function, although, the mutation at specific sites such as conserved residues can bring about a change in the structure and function of the protein.

Going in more depth, it is even possible to maintain the shape of the protein, but alter its function, for instance, through indirect, allosterical effects.

Although, the conformation of the mutant protein may be highly similar to the conformation of the wildtype, there could be alterations in their topologies at sites distant from the site of mutation.

In this category we also include active sites of enzymes, whereby proper amino acid residues interact with the substrate; their mutation does not change the shape, but can directly perturb/abolish the enzyme's activity (example).


How to save and load a text mode game

Question: I went in late in a project of gamedev of a simple text game in C++.I studied the project and I think I know how to do everything but i get stuck on a thing:how to save and load the game as proposed.I don't want to have the thing done for me,only you show me a way to do it.
Answer: Well the simplest way I can think of is to have a structure/class which represents the whole games "state." And on save you simply write this entire structure from memory to disk. Loading would be the opposite.
What format it is on disk is entirely up to you, if your state consists entirely of simple data types, you may just want to write a binary blob. Or you might want to go with something more versatile such as serializing it to XML, it's really up to you.
Answer: I've only taken a quick look at the post but here's my suggestion:
You game state might consist of a couple of structures and a few arrays of data. The structures would define the player(name, health, money, whatever), a weapon (attack, chance, etc), armor etc and so on...
First you would write the player's state by saving his structure. Next would would be the number of weapons owned by the player, followed by an array of weapon structures, the same for armor...
The file format would then be
STRUCT player
INT num_of_weapons
STRUCT weapon
STRUCT weapon
STRUCT weapon
INT num_of_armor
STRUCT armor
STRUCT armor

It can be easily done using fstream.
Answer: The process you are describing is known as "serialization"- that is, taking an in-memory object and converting it into some form that can be saved to disk. It could be as simple as a raw memory dump, or something complicated like XML.
I suggest taking a look at the wikipedia article on this subject: http://en.wikipedia.org/wiki/Serialization
Answer: I didn't read the website you linked to, but you'll probably want to write code that reads/writes to a basic text file in order to load/save your game.
First, figure out how to format your text file.  For example, if I'm writing a pacman game that allows the player to save games, the text file might look something like this:
5
54700
3

I would write my code to read the file one line at a time:
Line 1: the level the player is on.
Line 2: the number of points the player has.
Line 3: the number of lives the player has.
Do a Google search for C++ file input/output to figure out how to write the actual code.
Answer: XML serialization seems the easiest solution. With small lightweight libraries such as TinyXML it's even easier. As for making the files unreadable you can use simple XOR obfuscation with a short key. Or you could try JSON.
Answer: It all depends on how complex your save files would be.  If it's just a few integers than it's probably pretty easy to simply write a couple of functions that would write those values to a file in a specified order and then load them in the same order that they're written.  If it needs to be more complex and handle saving the values of multiple objects than serialization is your best bet.  If you're looking for a human readable save format I would suggest XML Serialization, otherwise you may want to look up some non-human readable formats.

How to save and load a text mode game


Meaning of 'upon which'

Question: I am not a native English speaker. I read this phrase in a book, '... more beloved than everything UPON WHICH the sun rises,...'
Could anyone clarify what this phrase means? And what is the meaning of 'upon which' here? Thanks
Comment: A modern version of that quote would be "More beloved than everything the sun shines on" (The author is saying that this thing is more important than everything in the whole world). This is form of english is rarely used now but it's essentially a reordering of "everything the sun shines upon".
Comment: It's always better to provide *context* (i.e. the surrounding passage) when asking what something means.  But I agree with Rathony.
Answer: upon (up + on) which the sun rises... the word "upon" in this case, it is similar to the word "over".. upon seems a little bit more formal for me..
Even the Oxford website gives that notion: http://www.oxforddictionaries.com/us/definition/american_english/upon
"More formal term for on, especially in abstract senses. it was based upon two principles a school's dependence upon parental support"
Think about all the things that are illuminated by the light of the rising sun (sun OVER everything).
For me, this phrase is very poetic and basically, means "something which is more beloved than everything".
Comment: This is not an explanation of the usage of _upon which_ in the question, which has nothing to do with being illuminated by the rising sun.

Meaning of 'upon which'


How do I interface an XBee wireless module with the Uno?

Question: I want to use an XBee wireless module with my Arduino Uno. How should I go about doing this? Do I need a shield like this one?
Answer: Xbee modules have a slightly non-standard pin header layout, i.e. two rows of pins with 2 mm pitch (separation between centers of adjacent pins) instead of the more common 2.54 mm pitch used in the Arduino itself.
Therefore directly connecting the XBee to the Arduino such as by plugging it directly in, is not possible even if the header pin rows were spaced sufficiently apart to match the header rows of your flavor of Arduino.
If jumper wires are used, then yes, the Arduino can directly interface with and fully use the XBee module: There is no additional electronics required to interface with the hardware of the module.
The pin connections required are:
<code>XBee                Arduino
------------        ------------
 VCC or 3.3V         3V3
 TX or DOUT          RX or 0
 RX or DIN           TX or 1
 GND                 GND
</code>
The addition of an XBee shield, or more usefully one of the various Sensor Shields with XBee footprint socket, is useful in creating a more robust set-up, not fragile as jumper wires are prone to be.
Notice the XBee headers on this shield for instance:

(source)
An added advantage of using such a shield is that 2mm pitch headers are not as easily available as standard 2.54mm ones, and when they are available, they work out quite expensive. The shield illustrated above, on the other hand, is for under $8 on eBay, and might be available for even less elsewhere.
Small price to pay for convenience, perhaps.
Comment: Worth noting that the XBee Pros cannot be safely powered through the Arduino's on-board 3.3V regulator as they draw too much current.
Answer: If you are asking how you use them, you basically have to setup RF network information on them. I provide information below on how you can learn how you setup the hardware to program them. You then can use a shield like the one you linked or just wire the pins as somebody else has suggested.
Did you decide between XBee series 1 or 2? If not, you should first read this article before you buy.
Here is the actual hardware I bought via https://www.adafruit.com/

1 ea.    XBee Adapter kit    $10.00
2 ea.    XBee Module - Series 1 - 1mW with Wire Antenna  $45.90
2 ea.    Shield stacking headers for Arduino (R3 Compatible) $3.90
1 ea.    USB FTDI TTL-232 cable  $20.00

You use the USB FTDI cable with the adapter as shown in this picture to program the XBee before connecting it to your Arduino, as it needs information about the radio network it should connect to.

Adafruit's learning section has this article with more information.
I would also make sure to read this article on common XBee mistakes.
I also happened across someone using an WiFly (XBee based board) without an adapter. Skip to 0:16 on this video.