How do the "spectacles" in Accelerando work?

Question: When Jack steals Manfred's glasses and puts them on, he somehow "becomes" Manfred from an "information dump" that comes.
But that doesn't make any sense because unless I'm mistaken, the glasses just display image and text no?
Answer: For most people yes they do only display images and text but Manfred has become so heavily dependent on his data feeds that his specs run his life. As such when Jack puts them on and starts to follow their advise he becomes the man whose life they have been programmed to run. It's not that his specs do anything different to anyone else's its that they do more, much more, of the same, to the point of almost being the person they work for.
Answer: I should probably start by linking the wikipedia articles for Virtual_assistant and Augmented_reality, as the glasses in Accelerando use a combination of the 2 technologies. Development in this area is ongoing today, and products similar to Manfred's glasses are now beginning to be realized in real life commercial products today. It is important to note that in the book, Manfred is a software developer, and has personally developed his own system, that is more comprehensive than what is generally available to the public, not to mention personally tailored to Manfred.
During the writing of Accelerando, these technolgies were still in their infancy. When the book was published in 2005, Google Glass did not yet exist, nor did Oculus Rift, or the iPhone for that matter. So when writing the character of Manfred Macx, Charles Stross had to use his imagination. In addition he was probably drawing inspiration from researchers like Steven Mann, inventor of EyeTap.
Ironically, events from the book somewhat echoed themselves in the real world in 2012 when Mann was assaulted while eating in a McDonalds in Paris with his family. The assailants were thwarted though by the fact that Mann's EyeTap was surgically bolted to his skull, and the would be muggers were unable to remove the device from his head.
Unfortunately in the book, Manfred did not have this foresight, and his glasses are swiped, leaving him temporarily incapacitated. It seams plausible that Manfred might be so incapacitated given his excessive reliance on them in the book. In the real world there is at least one report of someone becoming addicted to Google Glass in 2014, and subsequently going through withdrawal. Also internet addiction has been well documented for some time now.
As for Jack's ability to use the glasses. In the book, Manfred doesn't have a password or any biometrics linked to his glasses. This is most certainly for comic effect, as most modern devices these days already have these security features. But without this security hole, there wouldn't be much of a story if Jack had been locked out of the device. And there wouldn't have been the opportunity for comic relief when Manfred's Cartesian theatre AI has trouble interpreting the unfamiliar voice data from Jack(yes, if you read, you will find that he speaks to the glasses, and they speak back). Jack goes to Manfred's meeting in his place, in a misguided attempt to extort money out of Manfred's business contact, but the meeting does not go as expected, in part due to Jacks general ignorance, and inability to pass along information provided to him through the glasses. TLDR: It's not that Jack became Manfred, but more simply that Jack saw an opportunity to make a quick buck, and so followed instructions, only to later find out he was not up to the task of pretending to be someone he was not.


Why is the combustion of Nitrogen endothermic?

Question: Other combustion reactions are exothermic but this combustion reaction endothermic. Why ? Please explain..
Comment: consider the strength of the Nitrogen-Nitrogen triple bond
Comment: And, not all reactions with oxygen are exothermic - the ones that are tend to be called combustion reactions since, well, they actually combust.
Answer: As said in the comments a reaction with oxygen doesn't have to be exothermic it can be endothermic - as of this we only really say the reaction with oxygen is combustion if the reaction is exothermic.
In the example of the reaction of $N_2$ with $O_2$ several nitrogen oxides can be formed $N₂O$, $NO$, $N₂O₃$, $NO₂$, and $N₂O₅$. But well do an example of $NO$ formation as this one of most common products.
For a reaction the enthalpy change of the reaction using bond enthalpies is given by $$\Delta H=\sum{ broken}-\sum{ formed}$$
So are reaction for $NO$ formation is
$$N_2 + O_2\rightarrow 2NO$$ and the bond enthapy of $N\equiv N$ is 891 kJ/mol, $O=O$ is 495kJ/mol, and $NO$ is around 90.2 kJ/mol
Therefore $$\sum{ broken}=1386 kJ/mol$$
$$\sum{ formed}=180.4 kJ/mol$$
so $$\Delta H = 1389-180.4=1205.6 kJ$$
This means that $\Delta _f H[NO]=602.8 kJmol^{-1}$ this shows that the reaction is endothermic as $\Delta H$ is positive despite being a combustion reaction.
Comment: See https://chemistry.meta.stackexchange.com/questions/86/how-can-i-format-math-chemistry-expressions-here


Removing dotted assist lines?

Question: When I open the file directly from my desktop, these assist lines don't seem to show. But when I Append it, these random dotted lines appear that seem to point to its parented object. Is there any way to hide these lines, because they can start to get really distracting when animating.
Answer: You can hide that in display tab by deselecting Relationship Lines.
Press N while in 3D-view, then uncheck the option in "Display":
Comment: Could you add a screenshot showing where for people?
Answer: For Blender 2.8x
Click on the Overlays drop down menu (usually found near the top right corner of the 3D Viewport) and uncheck the box next to Relationship Lines.

Removing dotted assist lines?


What are synaptic and synaptics?

Question: I need an explanation of the meanings of "synaptic" and "synaptics".  Linux Mint 19.1 on a HP Laptop.  The laptop has a synaptics touchpad which I need to disable on bootup.  A config file to do this goes in the directory /etc/X11/xorg.conf.d/ and the filename seems to be variously called synaptics.conf or 50-synaptics.conf or 70-synaptics.conf
Comment: Hi and welcome to the site! Could you please [edit] your question and clarify what you are trying to do and what your problem is? Is your question "how can I disable the touchpad" or is it "what is synaptic"? And are you perhaps confusing `synaptic` and `synaptics` (a very understandable mistake)? If you want help with your cofig file, please include it in your question and use the [formatting tools](https://unix.stackexchange.com/help/formatting) to edit it as code.
Comment: alternatively you can choose to restrict touchpad functionality using [`syndaemon`](https://manpages.debian.org/xserver-xorg-input-synaptics/syndaemon.1). Eg, disable it while typing, or even disable only clicks while typing
Answer: Synaptics is a major manufacturer of laptop touchpads, and also the name of the widely-used Xorg touchpad driver that originated as a driver for Synaptics touchpads, but now covers other touchpad manufacturers' products too.
Synaptic without the s, however, is completely unrelated: it is a graphical APT package manager front-end for the GTK toolkit (i.e. native to the GNOME desktop).
Mint 19.1 is likely to use the newer libinput X11 input driver instead of the dedicated synaptics touchpad driver used in previous versions; beginner6789's answer to this question or man libinput may be helpful in configuring it.
Also, you can use the xinput command without any parameters to list the X11 input devices, and then use xinput --list-props <input device number of your touchpad> to view all the settings for it available through the current driver.
Before trying to manipulate the settings directly, note that your desktop environment may already be controlling some of the settings. For example, in KDE the "Synaptics Off" setting is controlled by the touchpad input device management of KDE System Settings: if you set the "Disable touchpad when typing" option, it will manipulate the "Synaptics Off" setting according to whether keystrokes have been recently detected or not.
Comment: Using the above xinput commands reveal that Mint 19.1 is using libinput rather than Xorg.
Comment: See my EDIT2 for /etc/X11/xorg.conf.d/99-stopit.conf file.
Answer: I am using the synaptics driver for my Elan1300 clickpad with voidlinux. Mint could be different.
In my /usr/share/X11/xorg.conf.d/ is 70-synaptics.conf file I copied to /etc/X11/xorg.conf.d/70-synaptics.conf and edited with my settings. The /var/log/Xorg.0.log file shows if the xorg is using the synaptics driver. The synaptics driver has settings to disable the touchpad when running the Xserver.
The touchpad using the synaptics driver can be turned off in the config file:
Option "TouchpadOff" "true"

That should disable the touchpad as soon as the display manager begins. Some desktop managers can affect the way xorg works with the input devices so that would be different. After X begins then the touchpad can be turned off in the .xinitrc file or other startup file like this:
synclient TouchpadOff=1

If the xf86-input-synaptics is not installed then the xf86-input-libinput might be activating the touchpad instead of the synaptics driver.
An excerpt from the Xorg.0.log file might have given better information and show how the touchpad is being setup or the xinput can also give some details.
The xorg.conf.d files could even be modified to ignore the touchpad in the evdev.conf, libinput.conf and synaptics.conf files and so prevent any touchpad driver from loading:
MatchIsTouchpad "on"
Option "Ignore" "true"

So I suppose the synaptics package would not be needed just to disable all touchpads in the evdev and libinput drivers.
EDIT: This might not be enough because the Xserver could activate the touchpad as a simple mouse instead of a touchpad. Then a MatchProduct would be needed to completely Ignore the touchpad.
Unless a touchscreen driver is needed then blacklisting the hid_multitouch kernel module can also disable the touchpad. And building a custom kernel is also an option...
EDIT2:
Try something like this to Ignore the touchpad no matter if Xorg tries to use the synaptics, libinput or mouse drivers:
Section "InputClass"
 Identifier "stop touchpad"
 MatchProduct ""
 Option "Ignore" "on"
EndSection

Put the above into a config file in /etc/X11/xorg.conf.d say 99-stopit.conf and see what happens. Be sure to put the correct string into the MatchProduct maybe just "Synaptics" or other substring could work. Also there are alternatives like MatchPnPID, MatchVendor explained in the "xorg.conf" man page.

What are synaptic and synaptics?


I'm not able to access a certain intranet site

Question: I'm using a Samsung Galaxy Tab (3.2 Android OS) on a wireless network to access an intranet site. I can access the site perfectly from a laptop connected (wireless) to the intranet site, but not with the Galaxy Tab. It's saying that it cannot locate the remote server (this is baffling). Additionally, I have tried several browsers: Firefox, Opera, and Android browser. Has anyone experienced something similar or have an idea what the problem may be. Thanks!
Comment: Can it access other intranet sites?  Is the laptop configured to use internal DNS servers?
Comment: No, the laptop is set for dhcp, here at my work. It accesses our intranet with no problem. The Galaxy Tab is using the same wireless profile, and can access all of the usual internet sites, just not our intranet site.
Comment: @Matthew Read - I don't think the laptop has a Connection-specific DNS Suffix configured.
Comment: @MatthewRead - on second look, yes it does. How would I add a Connection-specific DNS suffix to the Galaxy Tab, if this is in fact the issue?
Answer: It may be that your intranet sites are actually hosted on another subnet, and access is through a proxy server. Direct DNS lookup, and even IP routing to the host may not be possible.
The browser on your laptop might be automatically configuring the proxy, whereas the tab would not. I can be tricky to determine where the proxy server is, however it maybe possible with netstat and a little knowledge.
On the laptop, start downloading a large file from the intranet, and run this from a command prompt:
netstat -an
Look for a connection on a port like 80, 8080, 443, or 8443. This would be the server you need to configure as your proxy server on the tab.
It's also worth exploring the DNS suffix options suggested above.


Theil-Sen estimation, more than one independent variable

Question: Is the Theil-Sen estimation in robust regression only limited to a two dimensional problem or can you use it for more than one independent variable as well?
Comment: no, it's only limited to two dimensional problems. There are many, much better alternative though and those generalize trivially to higher dimensions (search for robust regression here).
Answer: There have been a number of proposals for extending Theil-Sen estimation to multiple regression contexts.
I'll point to a couple:
1)
Zhou, W. and R. Serfling (2007),
Multivariate Spatial U-Quantiles: a Bahadur-Kiefer
Representation, a Theil-Sen Estimator for Multiple
Regression, and a Robust Dispersion Estimator,
Journal of Statistical Planning and Inference, May
see here

2)
Wang, X., X. Dang, H. Peng, and H. Zhang (2009),
The Theil-Sen Estimators in a Multiple Linear Regression Model
see here or here (different versions)

The first is based on extending univariate U-quantiles to multivariate U-quantiles, and the second is based on a multivariate median.


If Descartes reasoned that nothing was knowable, why is "cogito ergo sum" exempt?

Question: For instance, if Descartes reasoned that knowing 1+3 with certainty was impossible, for an evil demon or other countless possibilities may manipulate his mind into believing it was indeed 5, shouldn't it be equally true that an evil demon forced his mind to believe that cogito ergo sum was also true, when perhaps, it is false?
Comment: Descartes reasoned that one can not be deceived about own existence because said existence is a precondition for getting deceived. But yes, this is a common criticism of *cogito*.  [Peirce wrote](https://philosophy.stackexchange.com/a/37363/9148), for example:"*Here is a man who utterly disbelieves and almost denies the dicta of memory. He notices an idea, and then he thinks he exists. The ego of which he thinks is nothing but a holder together of ideas. But if memory lies there may be only one idea. If that one idea suggests a holder-together of ideas, how it can do so is a mystery*".
Comment: Does this answer your question? [Could 'cogito ergo sum' possibly be false?](https://philosophy.stackexchange.com/questions/70/could-cogito-ergo-sum-possibly-be-false)
Comment: @Nelson Alexander Spinoza, who was the stand out Descartes interpreter of his time, (see the 'Cogito Metaphysica'), vigorously denied that it is physically and intellectually possible to deny anything known with certainty. This is no minor claim. It calls into question any validity for Descartes skeptical position.
Comment: Good observation, couldn't agree more. But old Rene pulled a fast one when he claimed that the only thing he could not doubt was the 'cogito'. Read that part again, break it down carefully so that you can respond to the comments you'll receive!
Comment: There can be NO DOUBT that the dreamer is one who must exist. Why?  To claim non-existent things can dream would make no sense. Furthermore, science people & math people would say if x is non existent them any property I give x will be deemed false. All unicorns are white is deemed false because unicorns are nonexistent. Thus unicorns can't possible dream. If I am a person who can dream then I must be an existing thing. Well we have existing things that are not alive such as stop signs. I need to prove I am alive now. But dead  things can't dream either. Inanimate things can't dream either.
Comment: Yes, there is plenty of retrospective criticism of Descartes' cogito. And today his idealism and his applications of a truthful deity are hard for us to grasp. That's why it's good to try to see all philosophical innovations in context. What's important here is that a very rigorous process of "doubting" can be followed to dismiss both traditional authority, Church teachings, the senses, but still arrives at a "doubter," a subjective consciousness or mind, if you will. This is a firmer basis of certainty, he argues, than anything "out there."  And this produced a clarifying new position.
Comment: @CM Saunders.  I don't know what Spinoza meant, since "known with certainty" is the issue. But I'm actually not so much talking about cogito per se as a tendency we can all have of not appreciating in retrospect why some famous method or claim was important at the time. Whenever I find myself explaining why, say, Descartes was wrong I have to stop and say....wait a minute, this is Descartes I'm talking about.
Answer: Descartes doesn't actually reason that nothing is knowable. In Meditation I he merely practises what is generally called methodological doubt. In constructing the foundations of knowledge he will not accept any belief if beliefs of that kind could be false. So he will not accept sense-based beliefs because the senses can deceive us. He will not believe that he is awake since when he is asleep he sometimes thinks he is awake, and when he is awake he thinks he is awake: so how does he know which state, awake or asleep, he is in? As for what he believes to be the truths of mathematics, how can he tell whether he knows these are truths and not merely matters which he psychologically cannot doubt, courtesy of the deceptions of the evil demon?
In spite of his language, Descartes does not in fact take the cogito as infallible knowledge even though he is certain of its truth as he is relatedly of the nature of the 'I' which exists - that it (he) is essentially a thing that thinks. He has been certain before - and wrong before. A deceiving God could have made him falsely certain - there is this bare, metaphysical posibility (Med III: tenuis et, ut ita loquar, Metaphysica dubitandi ratio est). So he sets out to discover whether there is or could be a deceiving God. 'For if I do not know this, it seems I can never be [justifiably] quite certain about anything else.'
He takes the cogito to be a clear and distinct idea, and he lays down a principle, a general rule (regula generali), in Meditation III that he can rely on any other ideas which are as clear and distinct as the cogito. 'I now seem to be able to lay it down as a general rule that whatever I perceive ... clearly and distinctly is true'. On this basis he 'proves' by what are evidently taken to be clear and distinct ideas the existence of a God who is no deceiver (Ex quibus satis patet illum fallacem esse non posse) - and God would be a deceiver if he did not guarantee the truth of clear and distinct ideas. The whole process is circular and is well-known as the 'Cartesian circle'. He uses clear and distinct ideas to prove the reliability of clear and distinct ideas.
So to underscore the point: Descartes does not 'exempt' the cogito, since the truth of the cogito has to be vindicated by demonstrating the existence of a non-deceiving God who underwrites the reliability of our clear and distinct ideas, of which the cogito is one (he thinks). That the whole process is circular, as described, is another matter. Since Descartes' general rule, 'that whatever I perceive ... clearly and distinctly is true', is also justified only by reference to God (Discourse, Part IV: it is a rule the truth of which is 'assured only for the reasons that God is or exists'), the circularity is reinforced.
References
Descartes, Meditations on First Philosophy, tr. J. Cottingham, Cambridge: CUP, 1996: 12-23 & 102-6.
Descartes, Discourse on the Method, tr. J. Cottingham et al., The Philosophical ritings of Descartes, I, Cambridge: CUP, 1985: 130.
Bernard Williams, Descartes: the Project of Pure Enquiry, London: Routledge, 2008: 93, 175-189.
Answer: The main point is that the Cogito is for each one of us to decide whether it is conclusive of not.
As I see it, only the subject knows that he knows. Knowledge is nothing but subjective experience: I know pain only when I am subjectively experiencing pain. Pain is nothing but whatever I am experiencing whenever I am in pain.
And then of course, it becomes trivial that Descartes knows he is thinking at the moment he is thinking and that therefore there is this thinking thing which is experiencing itself and therefore exists as such and knows it exists as such.
If you don't accept that you know you are subjectively experiencing pain whenever you are subjectively experiencing pain, so be it. It is for you to decide.
And if you define knowledge for example as what is written in scientific books, then you won't be convinced.
Comment: How does whether only the subject knows or the entire population answer the question of how Descartes knows his mind isn't being manipulated?
Comment: @Cell Deception implies you don't know. Either you know or you don't. If you do, manipulation is logically impossible. Goes for knowing and knowing that you know. To claim otherwise is not only saying that knowledge of anything is impossible, but also that the concept of knowledge is nonsensical. The idea that we can know yet be deceived is inconsistent but you can choose to believe it. We can be manipulated into believing things exists outside our mind but what we subjectively experience is as real as could be.
Comment: Deception means to be convinced into believing or knowing something that is not true and it involves manipulation. Not knowing is not the same as knowing something not true. I may not know the true shape of the spheroid planet Earth in as much as I don't know the exact geometrical parameters to draw a precise model, but flat Earthers know incorrectly that the Earth is flat and disk shaped. Different things.
Comment: @Cell Sorry, I don't get it.


Using references in setup scripts

Question: Setup scripts are versioned. It is known. As a result, any time you use a reference from an external object or class, you run the risk of the setup script itself changing ex post facto. For example, suppose I want to insert a new status that is the default for the "New" state:
$tbl = $installer->getTable('sales/order_status_state');
$fields = array('status', 'state', 'is_default');
$values = array(
    'unsubmitted',
    Mage_Sales_Model_Order::STATE_NEW,
    'is_default' => 1,
);
$conn->insertArray($tbl, $fields, array(array_combine($fields, $values)));

Maybe it's unlikely that a future release of Magento would change the value of Mage_Sales_Model_Order::STATE_NEW, but it could happen, and if it did, this setup script would have the same version number(s), but produce different results. That's bad!
The real question here is that good programming practice tells me that I shouldn't have the string 'unsubmitted' in my code/config more than once. I would really like to put it in config.xml, actually, but I can't, because if I do that then future versions of this setup script can change meaning without actually changing the code of the setup script.
Has anyone found a reasonable compromise between hard-coding values into setup scripts and maintaining pure differences between versions?
Answer: I think this is rather a non issue, something like Mage_Sales_Model_Order::STATE_NEW is never going to change to something which is completely unrelated to what it was before.  It will very likely never change at all but if it did it will just change to the next incantation representing the same thing.  If you are concerned about that, then you need to be concerned about it not only in setup scripts, but any class and method you write, or indeed any core class or method!
Comment: What about the 'unsubmitted' string and the best practice of not hard-coding values?
Comment: If that is a string you have defined for a module you are going to maintain then it's up to you how you maintain that.

Using references in setup scripts


Coworkers, employees

Question:
If I was the head of a department in a company, what would I then call the people in that department (who work under me)?

If I was the boss of a company, would the people in the company be my employees or are they only employees of the company or the person who owns the company?
Answer:
You may hear them called employees, but one common phrase that comes to mind is to say that they are "my team" (collectively) or "a member of my team" or "one of my team".

In this context I think you would definitely hear them called employees, even though they are technically employees of the company. You may also hear them called by their title and possibly described as "our" instead of "my", e.g., "he's one of my/our engineers", "she's one of my/our heads of department".
Answer:
One word used in business today is colleague. Lexico says

colleague
NOUN
A person with whom one works in a profession or business.

When this term is used by a manager in relation to those working in that department, it implies that they are all working together. Those who work there know who is boss, but a working relationship can be better if it isn't stressed more often than necessary.
Answer:
People who work directly under you are said to "report to" you. You can also call them your "direct reports".
They are employees of the company. Unless you are also an owner of the company, I wouldn't call them your employees. Some might, but I think this one is a matter of prefernce.

Coworkers, employees


How many stack cables would be needed if we want to stack two 3850 switches

Question: How many stack cables would be needed if we want to stack two 3850 switches :
We have one 3850 switch and planning to add one more.
So my guess is only one Power & One data stack cable would be fine.
Or please let me know if it is mandatory to loop the cable with two Power & two data stack cable?
Answer:
How many stack cables would be needed if we want to stack two 3850 switches : We have one 3850 switch and planning to add one more. So my guess is only one Power & One data stack cable would be fine. Or please let me know if it is mandatory to loop the cable with two Power & two data stack cable?

Minimum (and improperly), one stacking cable (data). However this is a bad idea as any issue with this cable will split your stack into standalone devices.
Minimum and properly, two stacking cables (data). Providing the loop is the proper (and documented) way to stack these switches. If one cable gets damaged or needs to be disconnected for some reason, the stack remains a stack.
The power stacking cables are purely optional, but add flexibility which can be useful and cost saving depending on the deployment. This allows the switches to "share" their power supplies with each other. Again, the loop is the correct way to utilize this feature.
Let's say that your power needs on each switch is about 400W. With the power stacking cables and a single 1100W power supply in each switch, you can have fully redundant power. Or you could skip the power stacking cables and put two smaller power supplies in each switch, which means you have four power cables to plug into outlets (if you can't use power strips --policy or regulation reasons-- this may exceed your available electrical outlets).
The actual implementation on power (and if you need the power stack cables) is going to highly depend on your situation and the potential future needs of your deployment. For example, if you know that there will be a VoIP rollout next year and you will need more power for PoE phones, you may want to leave the additional power supply slot available to add more power at that time.
Comment: Thanks ....thats explains in a very detailed.
Answer: A stack should be connected in a loop, with a stack cable for each switch. With two switches, that would be two stack cables, three switches three stack cables, etc. that means Switch 1 connects to Switch 2 that connects to Switch 3, etc. (up to a total of nine switches in a data stack), the last switch then connects back to Switch 1. With larger stacks, you may need to buy one longer stack cable.
Connecting the stack in a loop prevents splitting the stack when a switch or link fails. Not using a loop will create two separate stacks where each thinks it is the original stack.
The power stack works the same way, but there is a limitation of four switches for the power stack, so that more than four switches could be in a data stack, but you would have more than one power stack in the data stack. You also need to take into account the power used for the power stack, and the power supplies in each switch. You could get into a situation where you do not have enough power to power the stack, or you could have enough to power the stack in a failure, but not enough power to reboot a switch or the stack (rebooting require more power than running at a steady state).
Comment: It doesn't matter how many switches in a stack (as long as it is more than one). You could end up with two separate stacks that each thinks it is the stack. That can happen with two switches if the link between them fails. Each switch would think it is what remains of the original switch stack.
Comment: Thanks for prompt response. I was aware about multiple switches we need to make loop. But i had doubt for two switches.
Answer: For stacking two 3850 layer3 switches . Your require two power stacking cables and two switch (data)stacking cables


Making custom cursors on Ubuntu 20.10

Question: I want to create a custom theme with custom cursors on Ubuntu 20.10, but all tutorials/instructions I've found are at least 10 years old and don't work. Any tips?
Answer: It can't answer your question in detail, however, the following approach might be useful to you.
If you take a look at gnome-look.org you'll find the "cursor" theme section on the second position to the left side. In the provided link the author of that particular cursor-theme (submitted on 2020-11-15) and therefore fairly recent mentioned in his description below the preview:

This Cursor is built with clickgen and render with the puppeteer.

clickgen is (an) API for building X11 and Windows Cursors from .png files. clickgen is using anicursorgen and xcursorgen under the hood.
Puppeteer is a Node library which provides a high-level API to control Chrome or Chromium over the DevTools Protocol. Puppeteer runs headless by default, but can be configured to run full (non-headless) Chrome or Chromium

So you might look into those two applications and/or directly get in contact with that community for detailed information - who better is there.

Making custom cursors on Ubuntu 20.10


In 16.04, How to turn off the gray / darken feature when a window system is busy

Question: Ubuntu 16.04 windows or screen go dark when busy or not responding
Ive tried:
Go to System -> Preferences -> CompizConfig Settings Manager -> Effects -> Fading Windows and then just to option for Dim Unresponsive Window and you can set the option as per your requirement.
And Ive tried: Unity Tweak Tool
This doesnt seem to work in 16.04, and Im getting really tired of not being able to see much half of the time, even with core2 2.33 ghz and 8g of ram and a good ATI graphics card. It seems to gray out nearly anytime the system is
slightly busy
Answer: In 16.04 you can open CompizConfig Settings Manager by firstly making sure you have it installed:
<code>sudo apt install compizconfig-settings-manager
</code>
and secondly running it from the dash (click on swirly thing in top left and type compiz).
Once this is opened, click on Effects then untick the Fading Windows box.


Should I get a personal loan or a line of credit?

Question: Looking to buy a new computer.  While I can afford to buy it outright, I'm looking to get a loan to help make my credit a touch better.  But I'm wondering if I should just go with a line of credit, that way I have something for emergencies once the computer is payed off.  Will keeping the LoC paid up increase my credit score like a paid loan will?  Or should I stick with the loan?
Comment: Taking a loan to improve your credit score is like throwing yourself off a ship to improve your swimming.
Comment: @DJClayworth: It might seem like a no brainer to experienced people like you, and to me in hindsight,but I almost did the same 6 months ago. See my first few questions! My decisions then were based on feedback from family members and a credit union rep. The only reason why I didn't end up doing so is because of the replies to my question on this forum! +1
Comment: @DJClayworth "sink or swim" is a long-accepted method.  Besides, a thin credit history would be helped by a personal loan.
Comment: @RonJohn It's a method with a high fatality rate.
Comment: @DJClayworth quite true; it's very Spartan.
Comment: It's very "fictitious movie Spartan."
Answer: To help your score, use a credit card, and pay it in full each month. This should cost you nothing, and may get you some rewards depending on the card. Store cards don't really help the score as much as a regular credit card, and can hurt if you have too many.
Answer: Assuming you have a credit card, I recommend you use it for the purchase.
It gets you two things at the very least:

Gets the purchases reported as credit utilization. If you handle that correctly, you can improve your score
Most card vendors give extended warranty and return policies that a retailer or manufacturer does not without extra fees.

I buy all my electronics using my cards and not only does that optimize my scores but I have been able to enjoy painless/better RMAs for defective products just because my AmEx card would have refunded me the money anyways and the retailers knew it (AmEx would have recovered it from them in the end so it was in their interest to resolve the matter within 30 days)
Comment: The value of this answer could be greatly improved by mentioning that the card balance should be completely paid off before the next billing period, to avoid actually incurring interest charges.
Comment: Plus you would also accumulate some reward points i guess.
Comment: @Dheer: Oh yes, and more, but that depends on the card. I just mentioned the mere basics that can be guaranteed for any "good" card (I have heard some cards don't offer even those features like warranty manager, but have never come across them personally)
Answer: You're likely not going to get the result you desire from taking out a Personal Loan or a Line of Credit to pay for the computer and you'll pay dearly as well.
When it comes to credit, utilization (the amount of actual debt you have on revolving trade lines) is negatively inverted with your actual score. You'll also pay interest when you're carrying a balance on any loan without any reason to do so (why pay the bank money for no reason?)
The most important things you can have on your credit report is:

Payment History
Utilization

If you open the Line of Credit and have no balance carried at all it should report favorably on your credit report. This will help your utilization, payment history, and "Average Age of Accounts" (AAoA).
In short, you can use the Line of Credit or Personal Loan to enhance your credit, but there is no need to carry a balance to do so (and doing so can negatively affect your credit depending on how the account is reported).
Buy the computer using a Credit Card for some of the reasons already mentioned if they appeal to you, but don't pay interest unnecessarily as a sort of credit tax. It isn't a valuable use of your money.
Answer: Don't get a loan, just to improve your credit score. Being debt free is one of the best things in life.

Avoiding Debt completely:
If you don't have emergency fund, first set it up. The remaining money, you plan to buy new computer. If you don't have enough money, unless it is not urgent, save money and purchase it with your own money.

Still want to get loan due to lack of money:
If you don't have emergency fund, first set it up. The remaining money can be used to pay for the computer. The shortfall, can be adjusted through loan. I would suggest you to get personal loan, instead of credit cards. I would suggest you to get Personal loan, which is non-revolving one time credit and try to pay off as early as possible. Avoid debt in future. Don't go for line of credit or credit cards, which will make you to get in to debt again and again.
Comment: @Grade'Eh'Bacon, thanks for taking time to reply in detail. I have updated my answer.
Comment: A note - the "personal line of credit" is not quite the same as a credit card, though the concepts can be similar.
Comment: @Grade'Eh'Bacon, yes. I mean one time personal loan, not personal line of credit.
Comment: To clarify, what I mean is, the OP has asked for a comparison between a Personal Loan and a Line of Credit; I think your answer is accurate, but doesn't directly address what the OP has asked. However for these purposes of comparison, the points you have raised about revolving vs non-revolving should apply to either a line of credit or a credit card, so simply expanding your terminology to match the OP's should make this a better answer.


What's the difference between a PPA and a repository?

Question: I recently posted an answer where I wrote add the PPA. But I now realize, that I have no idea what the difference between a PPA and a Repository is. So can someone please explain it to me?
Comment: For PPA see: http://askubuntu.com/questions/4983/what-are-ppas-and-how-do-i-use-them
Answer: In short:

A repository is a collection of packages, hosted on an arbitrary server.
A PPA is also a collection of packages, hosted on the Launchpad servers.
Thus, a PPA is a special kind of repository. Like a square is a special kind of rectangle.

The main difference is the hoster. Basically, if you are a programmer and want to develop and distribute your own packages, and you have your own root server in the Internet, you can set up your own repository on it. Great! But what if you don't have a root server, and you don't want to pay for one, but still want to develop and distribute your own packages? Well, then there's Launchpad. It's offering PPAs as a service for exactly that use case. You can basically create your own repository on Launchpad, and manage your own packages there.
Let's have a look at an illustrating example.

First, assume you want to install the MATE Desktop Environment (a Gnome 2 fork) on Ubuntu Saucy Salamander. It is not contained in the official repos, nor do the devs maintain a PPA. Instead, they have their own repo. You could add it like so:
 $ sudo add-apt-repository http://packages.mate-desktop.org/repo/ubuntu

This would result in the following entry being added to /etc/apt/sources.list:
 deb http://packages.mate-desktop.org/repo/ubuntu saucy main

Second, assume you also want to have a look at Cinnamon  (another Gnome 2 fork). This is contained in the official repos since 13.04, but there's still a PPA maintained by the devs, useful for instance if you're interested in getting new releases quicker. You could add it like so:
 $ sudo add-apt-repository ppa:gwendal-lebihan-dev/cinnamon-stable

This would result in the following entry being added to /etc/apt/sources.list.d/gwendal-lebihan-dev-cinnamon-stable-saucy.list:
 deb http://ppa.launchpad.net/gwendal-lebihan-dev/cinnamon-stable/ubuntu saucy main

As you can see, the latter entry is quite similar as the one made in point (1). In fact, both are just URLs of repositories from Ubuntu's perspective.

In fact, you could even add the Cinnamon PPA with the same syntax as in point (1), although this is not the typical way for adding PPAs:
 $ sudo add-apt-repository http://ppa.launchpad.net/gwendal-lebihan-dev/cinnamon-stable/ubuntu

This would result in the following entry being added to /etc/apt/sources.list:
 deb http://ppa.launchpad.net/gwendal-lebihan-dev/cinnamon-stable/ubuntu saucy main

This is the exact same entry as in point (2). Only the files that these entries are written to are handled slightly differently, but in the end, it makes no real difference. In both cases, you will end up with the packages from the Cinnamon PPA being available on your system, always after the canonical sudo apt-get update, of course.
Comment: @jarno Yes, the manpage of `add-apt-repository` is indeed incomplete in that respect. Please use `add-apt-repository --help` to see that the URL form I used in 1 and 3 is indeed correct and an intended possible option. Furthermore, your assumption is absolutely correct: The GPG public key of a PPA will not be added when using the URL form. That's a useful addition, thanks! :) Please note that I do *not* recommend using the form described in 3 to add PPAs. It was just meant as an illustration to show that in fact, a PPA is simply a specific kind of repository.
Comment: According to manual of `add-apt-repository` in Xenial, if the `ppa:/` form is used, "The GPG public key of the newly added PPA will also be downloaded and  added  to  apt's  keyring." I suppose this is not the case, if the URL form is used. Actually, the manual does not tell you could use the kind of URL form you use in 1 and 3, but "a line that can be added directly to sources.list". Nevertheless, the form you use seems to work.
Answer: Repositories

On systems like Ubuntu, most software is packaged in nice .deb (or .rpm, like in Red Hat) files which contain the programs and libraries you need. These files can be downloaded or come in CDs (Ubuntu's CD is full of them). Repositories are servers which contain sets of packages.

PPA

Personal Package Archives (PPA) allow you to upload Ubuntu source packages to be built and published as an apt repository by Launchpad.

Also see What are PPAs and how do I use them?
and Wikipedia.
To sum it up:

A repository has packages.
PPAs are archives of personal packages.
Launchpad.net holds PPAs.
Comment: A PPA is not a package, it's a repository. Each PPA can contain multiple packages. Launchpad is (or rather hosts) a collection of repositories called PPAs.
Comment: Isn't a PPA just a repository or software selected and maintained by an individual or group? (who are not directly related to Canonical or Official Ubuntu devlopers). A PPA is like a repository and not a single package.
Answer: There is no technical differences between a repository and a PPA as far APT is concerned. Both are software repositories that offers packages, from APT point of view is the same mechanisms of installing packages.
PPA is a repository of packages that uses Launchpad as backend. Is just another name for the same thing, that is (at least in principle) normally used for personal reasons, which automates most operations you otherwise had to do manually or setting up your own services.
Repositories is wherever there is software, in this case, package lists and packages to be installed in Debian based distros.
You can have your personal repository, without the use of Launchpad and it could be called PPA, because is Personal.
The only difference in the usage is solely in the syntax of the add-apt-repository which uses the magic keyword ppa: instead of forcing the user to write the full url which is required for non Launchpad repositories.
Answer: A repository is a collection of various software which enables software like apt-get, aptitude etc. to download and install said software. Their content is visible for inspection by all.  Read the Ubuntu Help Page on repositories for enlightenment.
PPAs are special repositories for software which is not yet adopted for the entire community by the distro leadership. PPA software can have defects and can even be used for malware because they are not extensively reviewed as as the general repositories. For more, see Launchpad's explanation of PPAs and this discussion of PPAs.
Answer: Repository is  a place where package are stored or maintained for download or update.These  are servers which contain sets of packages.
A Personal Package Archive (PPA) is a special software repository for uploading source packages to be built and published as an APT repository by Launchpad or a similar application. Mostly it is maintained by people who are not  official Ubuntu developer


Convert backslash-delimited string into an associative array

Question: I have a string like this:
key1\value1\key2\value2\key3\value3\key4\value4\key5\value5

And I'd like it to be an associative array so that I can do:
echo $myArray['key1']; // prints value1
echo $myArray['key3']; // prints value3
//etc...

I know I can explode on the backslash, but not sure how to go from there.
Answer: Using a simple regex via preg_match_all and array_combine is often the shortest and quickest option:
 preg_match_all("/([^\\\\]+)\\\\([^\\\\]+)/", $string, $p);
 $array = array_combine($p[1], $p[2]);

Now this is of course a special case. Both keys and values are separated by a \ backslash, as are all pairs of them. The regex is also a bit lengthier due to the necessary double escaping.
However this scheme can be generalized to other key:value,-style strings.
Distinct key:value, separators
Common variations include : and = as key/value separators, and , or & and others as pair delimiters. The regex becomes rather obvious in such cases (with the /x flag for readability):
 #                    ↓    ↓    ↓
 preg_match_all("/ ([^:]+) : ([^,]+) /x", $string, $p);
 $array = array_combine($p[1], $p[2]);

Which makes it super easy to exchange : and , for other delimiters.

Equal signs = instead of : colons.
For example \\t as pair delimiter (tab-separated key:value lists)
Classic & or ; as separator between key=value pairs.
Or just \\s spaces or \\n newlines even.

Allow varying delimiters
You can make it more flexible/forgiving by allowing different delimiters between keys/values/pairs:
 #                    ↓      ↓       ↓
 preg_match_all("/ ([^:=]+) [:=]+ ([^,+&]+) /x", $string, $p);

Where both key=value,key2:value2++key3==value3 would work. Which can make sense for more human-friendlinies (AKA non-technical users).
Constrain alphanumeric keys
Oftentimes you may want to prohibit anything but classic key identifiers. Just use a \w+ word string pattern to make the regex skip over unwanted occurences:
 #                   ↓   ↓    ↓
 preg_match_all("/ (\w+) = ([^,]+) /x", $string, $p);

This is the most trivial whitelisting approach. If OTOH you want to assert/constrain the whole key/value string beforehand, then craft a separate preg_match("/^(\w+=[^,]+(,|$))+/", …
Strip spaces or quoting
You can skip a few post-processing steps (such as trim on keys and values) with a small addition:
 preg_match_all("/ \s*([^=]+) \s*=\s* ([^,]+) (?<!\s) /x", $string, $p);

Or for instance optional quotes:
 preg_match_all("/ \s*([^=]+) \s*=\s* '? ([^,]+) (?<![\s']) /x", $string, $p);

INI-style extraction
And you can craft a baseline INI-file extraction method:
 preg_match_all("/^ \s*(\w+) \s*=\s* ['\"]?(.+?)['\"]? \s* $/xm", $string, $p);

Please note that this is just a crude subset of common INI schemes.
Alternative: parse_str()
If you have a key=value&key2=value2 string already, then parse_str works like a charm. But by combining it with strtr can even process varying other delimiters:
 #                         ↓↓    ↑↑
 parse_str(strtr($string, ":,", "=&"), $pairs);

Which has a couple of pros and cons of its own:

Even shorter than the two-line regex approach.
Predefines a well-known escaping mechanism, such as %2F for special characters).
Does not permit varying delimiters, or unescaped delimiters within.
Automatically converts keys[]= to arrays, which you may or may not want though.

Alternative: explode + foreach
You'll find many examples of manual key/value string expansion. Though this is often more code. explode is somewhat overused in PHP due to optimization assumptions. After profiling often turns out to be slower however due to the manual foreach and array collection.
Comment: How would the regex look if you have a string that includes tab jumps like that: key1=value1\tkey2=value2\tkey3=value3 ?
Comment: @EchtEinfachTV More like that: http://stackoverflow.com/questions/168171/regular-expression-for-parsing-name-value-pairs - Albeit there are simpler approaches (replacing `\t` with `&` and then a `str_parse()`, or with a regex `\t(\w+)=(\w+)` or something). Please post a new question however if you have a different source.
Comment: @mario Thanks, I stumbled over parse_str() and use that now:

// convert tab jumps to & to be able to use query function
`$toURL = str_replace("\t","&",$keysValues);`
// parse as URL
`parse_str($toURL, $data);`
// access keys in array
`$postid = $data['postid'];`
Answer: What about something like this :
$str = 'key1\value1\key2\value2\key3\value3\key4\value4\key5\value5';
$list = explode('\\', $str);

$result = array();
for ($i=0 ; $i<count($list) ; $i+=2) {
    $result[ $list[$i] ] = $list[$i+1];
}

var_dump($result);

Which would get you :
array
  'key1' => string 'value1' (length=6)
  'key2' => string 'value2' (length=6)
  'key3' => string 'value3' (length=6)
  'key4' => string 'value4' (length=6)
  'key5' => string 'value5' (length=6)

Basically, here, the idea is to :

split the string
which will give you an array such as 'key1', 'value1', 'key2', 'value2', ...
and, then, iterate over this list, with a jump of 2, using each time :

one element as the key -- the one pointed by $i
the one just after it as the value -- the one pointed by $i+1
Answer: I am not that good with RegExp but how about this one line code
parse_str(preg_replace("/key(.*?)\\value(.*?)(\\|$)/", "key$1=value$2&", $input_lines), $output);

Answer: @Wasim's answer which

does not work as posted and
of which @mario lists the caveats of its use

can be improved / made more flexible by using a mix of negated character classes and escaped literal backslashes to establish a querystring.
Code: (Demo)
parse_str(preg_replace('/([^\\\\]+)\\\\([^\\\\]+)\\\\?/', '$1=$2&', $string), $output);
var_export($output);

Output:
array (
  'key1' => 'value1',
  'key2' => 'value2',
  'key3' => 'value3',
  'key4' => 'value4',
  'key5' => 'value5',
)

Otherwise, you can explode, chunk, and manually assign the elements.
Code: (Demo)
$result = [];
foreach (array_chunk(explode('\\', $string), 2) as [$key, $val]) {
    $result[$key] = $val;
}
var_export($result);  // same output as snippet above

Or a body-less foreach() with array destructuring: (Demo)
$result = [];
foreach (
    array_chunk(explode('\\', $string), 2)
    as
    [$key, $result[$key]]
);
var_export($result);

Or use looped strtok() calls: (Demo)
$result = [];
$key = strtok($string, "\\");
while ($key !== false) {
    $result[$key] = strtok("\\");
    $key = strtok("\\");
}
var_export($result);


Network says "Bridged" but no bridge exists

Question: So I'm having trouble removing a network bridge that doesn't actually exists, here's a screen shot. Anyone have any ideas? http://puu.sh/2lOlB
Comment: What have you tried? Right clicking the icon and un-bridging should be all thats required...
Answer: From the screen shot it is evident that the network card is bridged with your wi-fi connection.So you can either place your mouse pointer on your wifi connection and right click on it and then you will get an option to unbridge the connection,click on it to unbridge the connection.If this doesnt work you can try uninstalling the network drivers from the device manager or from the control panel and restart your system once.Best Regards, Joel from http://morningtadka.com - Best Technology blog
Comment: Yeah, there were no options to remove a brige - there was some sort of glitch going on. Anyway, reinstalling the network card drivers did the trick, thanks for your reply.


Why wont /testfor work?

Question: I've been trying to do /testfor @a [r=5] for something, but it wont work! It just gives me an error message like "Data tag" something something "Unexpected "[" as first char." I've done the command before and it works, so why won't it work now??
Answer: Once again, you have put a space in between the @a and the radius selector.
Correct command: /testfor @a[r=5]
A redstone comparator coming out of the block will emit a signal when this is true.
Comment: oh my god I seriously did it again xD I feel so dumb lol.
Thanks :P
Answer: You put a space in between @a and [r=5].
The correct command is this:
/testfor @a[r=5]

The "/" is optional.

Why wont /testfor work?


ShareKit for iphone - SHKShareTypeText

Question: I am using ShareKit for iphone to share some text in facebook. Can any one tell me which delegate is called after publishing the text successfully. I need this to inform the user that his action was successful.
Answer: The shareDelegate property in SHKSharer isn't the easiest to get to and change, but there are notifications sent from the delegate methods of SHKSharer, one for each of the methods: SHKSendDidStartNotification, SHKSendDidFinish, SHKSendDidCancel, SHKSendDidFailWithError. Observing these notifications turns out to be a simple way of listening for the outcome of sharing.
Answer: See shareDelegate property of SHKSharer .  All the concrete sharers (e.g. SHKFacebook) extend this base class.
Having said that, I'm not sure where you set a class to be the delegate using ShareKit's public API (so I'm not claiming this to be a complete answer).

ShareKit for iphone - SHKShareTypeText


What capacitor to get for relay coil?

Question: I refer to the diagram from this thread: What is the use of the capacitor in this relay circuit?, which is also shown below. If I were to use a capacitor for my relay coil (12v latching type) which already has a flyback diode installed, what voltage rating, capacitance and type (e.g. electrolytic, ceramic) should I be looking at?
Also, if I were to use multiple capacitors for my set-up, would combining different types of capacitors be ok (e.g. electrolytic, ceramic), or not recommended?
Answer: Paralleling the coil with a capacitor can work the driver quite a bit harder (possibly causing it to fail) and may cause a brief dip in the 24V supply- which could cause glitches. If the driver is relatively slow or the current is limited it may be useful to reduce EMI from the coil, however the contacts usually dominate the noise and in any case the driver circuit will likely determine how big you can safely make the capacitor.
Chances are a reasonable value would be some nF and best served by a ceramic capacitor of adequate voltage rating.
Comment: The relay I am using is this: DSP2a-L2-DC9V;  https://au.mouser.com/ProductDetail/Panasonic-Industrial-Devices/DSP2a-L2-DC9V/?qs=sGAEpiMZZMtSzCF3XBhmW7Mf2%252b5VGBAXF7qpk1GtcJU%3D. And just for my own learning, why would you recommend a ceramic capacitor over the other types?
Comment: It's cheaper and smaller, and generally has as-good or better characteristics than a film capacitor in that capacitance and voltage range. Electrolytics are not in the running (too low capacitance for them to be required, and you only use them when they are required because their life is more limited and they are relatively bulky).
Answer: I strongly suggest you to don't use capacitor in this system, it's not AC and you don't need to compensate the coil reactive current.
Contrarily it creates problems, it creates a peak of current which may generate undesired spikes in the power line, it stress the driver with peak current, it slows the rise of voltage in reflecting to a weaker connection during the contacts approach. No one is using this condensers in DC systems
Comment: Welcome to the site. I suggest that you check you posts for typos and spelling as these can make understanding difficult. [I've been posting here for years and still find myself including typos which need editing ! :-( ]. I've made a few changes in your post. Please check these to ensure it still says what you intended.
Answer: The capacitor is not needed.  The diode may also not be needed even if the relay did not have one.  The drivers I've used in the past had the diode built in.  See ULN5801 etc.
Comment: I once tried a relay setup with my raspberry pi device without using flyback diode to the transistor, and it eventually started malfunctioning, got warmer, before it smoked. So I probably would continue using the diode. The reason why I want to implement the capacitor is that I suspect the flyback diode may not be enough for my circuit, as other components seem to be malfunctioning in the circuit, however I am just speculating at the moment.
Comment: Are you sure a diode is built in to the relay?  I've used very similar relays and don't remember a diode.  The schematic does not show one.
Comment: There is no diode in the relay. So I've connected my own flyback diode.
Comment: @Craver2000  If the relay does not have a diode it is almost always necessary to have some form of energy recovery/dissipation and voltage limiting circuitry in place. Without a formal sink for the stored inductor energy it WILL find an informal sink. Without a formal voltabe limiter the voltage WILL rise to whatever level is required to transfer the energy from the coil to the sink.
Answer: Most people don't use one.
the Diode is going to catch most of the energy when the relay switches off, so the capacitor is only needed for the short period before the diode starts conducting, if that's a problem, use a slower switch.
Comment: The reason why I want to implement the capacitor is that I suspect the flyback diode may not be enough for my circuit, as other components seem to be malfunctioning in the circuit, however I am just speculating that it might be have to do with some residual inductive spike from the relays. A couple of I2C devices failed over the past several days when used with a raspberry pi device. They are implemented in a circuit where the power supply is controlled by a few latching relays which switches between two types of power supply of same voltage.

What capacitor to get for relay coil?


Decay of an electron not in eigenstate

Question: Suppose the electron of a single electron atom is in the state $ a|{E_{1}}\rangle + b|{E_{2}}\rangle $. If it decays to the ground state $ |E_{0}\rangle $ which spectral lines do I expect to see? The ones that correspond to the transition from $ |E_{1}\rangle $ to $ |E_{0}\rangle $, the ones that correspond to the transition from $ |E_{2}\rangle $ to $ |E_{0}\rangle $ or neither? My guess is that "right before the decay" the electron's wave function collapses to $ |{E_{1}}\rangle $ with a probability $ \lvert a \rvert ^{2} $ or $ |{E_{2}}\rangle $ with a probability of $ \lvert b \rvert ^{2} $ and then it decays to $ |E_{0}\rangle $, therefore I expect to see the spectral line of the transition $ |E_{1}\rangle $ to $ |E_{0}\rangle $ with a probability of $ \lvert a \rvert ^{2} $ and the other one with a probability of $ \lvert b \rvert ^{2} $. Is my reasoning correct?
Answer: You will observe transition $E_1\rightarrow E_0$ with probability $|a|^2$, and transition $E_2\rightarrow E_0$ with probability $|b|^2$.  Of course, if you literally made one measurement on a single electron, you would observe only one transition. However, in practice you either observe an ensemble of identical systems or the same system multiple times.
Comment: Exactly. The collapse (decoherence) happens due to the measurement, not as long before it as before emission.

Decay of an electron not in eigenstate


Does the background of the title crawl change across the films?

Question: All of the Star Wars films open with a title crawl against a starry backdrop, and then a pan downwards onto whatever setting has the privilege of hosting the opening scene. Since the films don't all start in the exact same place, do the stars change to reflect the different locations?
Comment: Given that the text's shape and color varied from movie to movie, I'd be way surprised if the stars were consistent.
Answer: Yes, the star field in the background changed. Compare the following screenshots, from starwars.com.


Kha'Zix's Q on hit proc

Question: Does Kha'Zix's Q proc on hit effects? If so, does it proc Feral Flare as well?
Does Farel Flare proc on on hit effects in the first place (Ezreal's Q etc)?
Comment: As a general rule of thumb, the only abilities that apply on-hit effects are either Attack Enhancers (Wu's Crushing Blow, Nasus siphon strike comes to mind), or abilities that state that they actually do apply on-hit effects (parrley, mystic shot, etc). Any bonuses consider them as auto-attacks (with a few math tweaks here and there). So yeah, if an ability applies on-hits, it will say so.
Answer: Kha'Zix Q is a normal single target spell which deals physical damage and it does not apply on-hit effects. It does however benefit from Spellvamp and It will also apply Rylais slow and the Muramana passive (bonus damage to toggle).
Feral flare will only proc with Autoattacks or spells that apply on-hit effects (Ezreal Q, GP Q, Yasuo Q etc) and not with other spells.
Also a spellshield will block all spells, including those applying on-hit effects.

Kha'Zix's Q on hit proc


Energy-Time Uncertainty Principle and Photons

Question: Heisenberg's uncertainty principle states that:
$$
\Delta E \cdot \Delta t \ge \frac{\hbar}{2}
$$
It is clear that this has nothing to do with the accuracy of our measurements, but rather is a fundamental 'law' in the quantum world. Now, we also know that photons do not experience time because of the Lorentz transformation time dilation:
$$
\gamma t = \frac{t}{1-\frac{v^2}{c^2}} = \frac{t}{1-\frac{c^2}{c^2}} = \frac{t}{1-1} = \frac{t}{0} = \text{undefined}
$$
Is the uncertainty principle not relativistic? Thanks.
Comment: What kind of reasoning is this?  What, on your understanding, does the symbol $\Delta t$ represent in the energy-time uncertainty relation?  http://physics.stackexchange.com/q/53802/
Comment: A change in time.
Answer: The relation says that it would take about $\Delta t$ time to measure the energy with an error of order $\Delta E$. $\Delta t$ is not the photon time, it is the time in the observer's (laboratory) frame of reference.
Answer: The question is correct in that the relativistic (or lorentz-invariant) time-energy uncertainty relation is a bit different (but still there is)
For example here is a pre-print Lorentz-Invariant Time-Energy Uncertainty Relation for Relativistic Photon, arxiv
Abstract:

The time-energy uncertainty relation is discussed for a relativistic
  massless particle. The Lorentz-invariant uncertainty relation is
  obtained between the root-mean-square energy deviation and the scatter
  of registration time. The interconnection between this uncertainty
  relation and its classical analogue is established.


Acousto-optical modulator (AOM)

Question: Suppose the RF frequency of the driver of an AOM is 40 MHz. I understand that it will Doppler shift the diffracted first order beam by 40 MHz but how does it modulate the amplitude of that first order beam by 40 MHz. I am just trying to understand that whether the Doppler shifting and the amplitude modulation both take place simultaneously or are in some way related phenomenon.
Answer: Doppler shift and amplitude modulation are two separate characteristics of the modulator.
For the first order, laser frequency is shifted by 40 MHz as you stated.
Laser amplitude is modulated by the RF envelope, not RF frequency.
Changes in RF envelope are slower than 40 MHz. They may be up to 30% of the RF frequency and usually much lower. This rate of envelope changes depends on the RF generator bandwidth, electro-acoustic transducer bandwidth, laser spot size and more.
Comment: Thank you very much for the response. I was wondering if  AOMs are available which can amplitude modulate a laser beam below 4 MHz. Most of them are mentioned as having the driving RF frequency in range of tens of Megahertz .
Comment: The speed at which an AOM can modulate a beam depends on the diameter of the beam and the time it takes for the sound wave to traverse the diameter of the beam. So for the fastest operation, you want a small beam located right next to the transducer, but you will be still limited by the speed of sound and the diameter of your beam. With a very small beam, you can probably manage 4 MHz but with reduced diffraction efficiency.

Acousto-optical modulator (AOM)


Is it viable or possible to make your own transistor?

Question: Just wondering if it is possible/viable to construct your own transistor, not small like todays, but the same scale as the one created at Bell Labs.
Comment: Besides PN-junction based devices, there are electrochemical transistors. Certain types of polymers can undergo chemical processes to switch them between conducting and insulating states. Place a polymer like this next to an electrolyte and then apply a field across the interface. The field strength & direction modulates this chemical process, and thereby the resistance of the device. You can reasonably achieve a gain of 5000-100000 & the process & chemicals are friendly to work with, but limited to low frequencies (sub-kHz). I'd expand this into an answer, but question is protected.
Answer: You might find the Yahoo "home_transistor" group a useful resource.
There's also a series of videos on YouTube by Jeri Ellsworth including some where she makes transistors.  In one, in particular, she takes the crystal out of a germanium point-contact diode and turns the crystal into a point-contact transistor (much like the Bell Labs transistor.)
There are a couple of semiconductor materials that are easy (and relatively safe) to make at home.  One is cuprous oxide.  H.P. Friedrichs has a page where he shows how to make a copper/cuprous oxide diode.  (The copper/cuprous oxide junction is a schottky barrier).  There's also a page at the science cupboard where they make cuprous oxide diodes.
Another easy home semiconductor is titanium dioxide.  Here is a page at University of Wisconsin talking about how to make titanium dioxide solar diodes.
Transistors are hard to make because they require two rectifying junctions, one of which, the emitter, needs to be injecting.  (The emitter needs to send minority carriers into the base.)  Thus the emitter/base junction needs to be either P+/N or N+/P.  If you are using Schottky junctions, as the first Bell Labs transistor did, then only certain metals form injecting barriers while most do not.  Additionally the base on a transistor needs to be narrower than the recombination distance for the material you are using.  For most materials this is less than 10 microns (which is a distance you can work with at home, but only with a great deal of care.)
It might be easier to start out with a JFET or a MESFET.  These will exhibit switching behavior but require only a single rectifying junction.  (A P/N semiconductor junction in the case of a JFET and a metal/semiconductor Schottky junction in the case of a MESFET.)
I've been trying to make a cuprous oxide mesfet, but haven't had any luck yet.  (Honestly, I've been doing more "research" than "trying", so it might not actually be that hard.)
Answer: I do believe that yes. The most hard part will be to obtain the materials.
If you manage to get a good piece of n-type (or p-type) Silicon, big enough to allow you to work with home tools, you'll "just" have to do local oxidation (with temperature for example) and make some soldering.
Of course, the quality of that transistor would be very doubtful as it would likely damaged in the first operation attempts...
Answer: There is this new one transistor made from wood and some chemical. It is 1hz transistor. So it seem we could make simple transistors without sophisticated machinery for simple calculator even if all machine were being destroyed
https://www.tomshardware.com/news/first-wood-transistor
Answer: Just get 3 steel plate and rust one of them with a solding iron and touch the tip of the 2 steel plate on the rust. This is a pnp transistor


Show users exact causes or misusings that lead them to be banned so they can fix them

Question: Don't you think people need to know what they did wrong exactly so they can fix it and get unbanned from asking questions or posting answers?
Answer: I went ahead and undeleted your last five or six self-deleted posts.  All your deleted questions are almost certainly what caused the ban (because you've asked relatively few questions and a high proportion of them were deleted).  None of those questions were downvoted, but try to improve them anyway to see if you can get some upvotes and answers (answer them yourself if you can).  In the future, don't just delete old unanswered questions, try and improve them instead.  Also, check and see if undeleting these posts alone unbanned you.
Side note: I agree with the reasons we don't tell people exactly what the ban rules are, but I think self-deletion is one case where we should at least warn people that what they're doing is actively harmful.  People who are just trying to clean up seem very likely to read such a warning.  People who are just trying to game the system by deleting/re-asking are lazy sods who won't read the warning.
Comment: Thanks for your answer @Bill the Lizard.This is exactly what I meant. Warning people when doing wrong. especially deleting questions. I thought that I made something good cause I didn't waste people time to read and answer them.
Answer: The error message you get when you're question banned is:

Oops! Your question couldn't be submitted because:

Sorry, we are no longer accepting questions from this account. See http://goo.gl/C1Kwu to learn more.

The answer one is similar; both link to What can I do when getting "We are no longer accepting questions/answers from this account"?, which is a pretty massive answer that explains what the user did wrong, how to fix it, and how to avoid it happening in the future
If you're looking for something that specifically says which posts caused it, it's probably the posts picking up downvotes and getting deleted, but (as that page says) the exact algorithm is secret to prevent gaming. If you're looking for something that specifically says why the posts were downvoted/deleted, an automated system can't really do that; hopefully users are leaving comments explaining what's wrong as they downvote
Comment: And don't delete questions. If you read the full explanation of your ban, then you will see that deleted questions factor into the ban. They more or less signal that you ask bad questions. Improve them if anything.
Comment: The problem is ex: in my case i cannot identify what's wrong in my questions, almost answered correctly, but i'm prevented from asking questions..I don't see what to do the get unbanned. In such cases I think people need help to resolve their issues.
Comment: I deleted unanswered questions an flagged answered ones but still banned from asking questions :(. I read what the answer in that link but i think still need help to show me exactly my faults so I can fix them I think it needs to be humain-being help not straight forward advice.
Comment: Thanks, good to know that. but now after being banned caused by deleting questions. how can I fix that ?
Comment: So you're question banned? Did you remove any downvoted questions?
Comment: On thing I can surely recommend is [to stop doing this](http://stackoverflow.com/questions/12062936/communicate-to-a-view-of-a-modulea-from-moduleb-in-prism). You admittedly completely changed your question to circumvent the ban. If you want to be unbanned, that is absolutely the wrong and most inappropriate approach. (I have rolled the question back to its original)
Comment: Do you think you could improve those questions? You could ask a moderator to undelete them for you. Perhaps you can then edit them back into shape. Top tip: Read the full question and answer at the link your receive which explains your ban.


How do I memorize hand signals faster being called out as a play during football?

Question: I'm in high school football, currently playing as a wide receiver and corner. I was wondering what is an easy way to memorize plays. I have such a hard time doing this when the coaches end up calling the play or when they signal it with their hands. I really need help on how to memorize and get used to this tactic they use with their hands in order to be successful. Can someone help me with this?
Answer: Make a video of each hand signal and draw the play associated with each hand signal. My school's football team also does a lot of hand signals and this helped me out. Also I don't know if your coach does this, but my coach's hand signals can be related to the plays. For example, one play we run is called "Paper" and my coach's hand signal is opening a book. Another play we run is "Flex" and the hand signal is a bicep flex.
Answer: I played as a WR in college, and now coach the QBs. What works best for me is to get a list of the play calls, and write down what the hand signals are for each part of the play. Then go through the list of plays and give the signals to yourself in front of a mirror as if you are the coach. By teaching yourself to call them you are also teaching yourself to recognize them. This worked great for me (even though we have over 100 signals), hope it works for you! (If you aren't near a mirror you can just do it without one.)
Answer: They sell blank flash cards, with rings to hold them together, on Amazon. Maybe you would find it helpful to put the hand signals on this type of flash card. I find it a good way to stay organized when I need to memorize a lot on a specific topic.


How to tip room cleaning in the US if you don't use cash?

Question: As a matter of habit, I never deal with cash while staying in the US. All I have on hand is a few credit cards, which also means using the ATM would incur fees. At the same time I am aware that it's expected to leave a tip to room cleaning, at least in 3+ star hotels. But how am I supposed to do this if I don't use cash? Is it expected that one takes out a few bills just for tipping purposes? Or should I ask the reception to add a tip to my bill?
Comment: Downvoted as this is not a travel problem but a result of unwillingness to deal with a financial choice.
Comment: @Willeke it is both a travel problem and a result of unwillingness to deal with a financial choice.
Comment: @RoddyOfTheFrozenPeas how would one do that if they don't normally use cash? I especially like using cards because my bank generates live stats on how much I spent on travelling, groceries, eating out, etc. When I somehow do have cash I immediately top up my bank so that I can just pay for everything by tapping and getting accurate spending stats.
Comment: @kiradotee - no idea what you're talking about, sorry. My comment was in reference to the fact that ATMs often only dispense $20 bills. So if you did withdraw cash you'd then have to break it into smaller denominations.
Comment: Additionally, unless you were planning on tipping in multiples of $20, you'd then have to break whatever larger bill was dispensed into smaller denominations.
Comment: There are workarounds to ATM fees.  A trick that many travelers use is to use their debit card and get cashback from a convenience store.
Comment: Get a bank that reimburses ATM fees.  I know there are at least two of them.
Answer: Yes, you are expected to have some cash for tipping purposes. You might also need it if a bellman carries your bags to/from your room or you receive other tipped services. Many people don't tip housekeeping, but if you're going to leave a tip, do it in cash. The front desk should be happy to make change if you need it; they want you to be able to tip. With planning, ATM fees can be low to zero, and you can further reduce their effects by taking out more cash and holding onto it if you travel to the US more than once.
Asking the front desk to add a tip to your bill would be unusual and may not be something the hotel could handle (besides a hotel restaurant and room service). I'd have little confidence of it working, or the tip actually ending up with the correct person.
Not all businesses in the US take credit cards, and small independent businesses will often prefer cash for small purchases, so it's helpful to have a bit of cash on hand anyway for something as simple as a water or soft drink from a cart on the street.
Comment: @JonathanReez you are not unable to; you are choosing not to.
Comment: @jonathanreez come ooooon if you can afford to travel, you can afford a little atm fee. Show the people who pick up after you some love.
Comment: @JonathanReez it is for you to weigh the importance of the tip against the hassle of dealing with cash.  If you decide that the latter outweighs the former, that does not change the fact that the responsibility for the decision is yours.
Comment: Just to add another thought: tipping in cash provides more anonymity and leaves all money at the tipped person - tipping by card means that the payment provider takes its fees and that the money ends in the hotel's base account. So, even if you could pay the tip by card (as the hotel might provide that option), it should not be prefered: tip the people directly, without any middleman
Comment: Request a cash advance from the hotel front desk, explaining that you will use the cash for tips. And do not forget to tip the staff that get you the cash.
Comment: In a pinch, you could also tip in your local currency.  While not ideal, in places like New York, London, Singapore, it's probably common enough that the staff can deal with it.
Answer: If you don't want to tip the people who serve you in the US, then don't stay in a hotel, eat in a restaurant, etc. That's the only real answer.
When you travel to other countries, you are expected to make at least a token effort to accommodate local customs and expected behavior, even when it's inconvenient. Tipping service people in the US is expected behavior. In a restaraunt, you can add the tip to the bill and pay with a credit card, but tipping hotel bell service / coatcheck / housekeeping / valet / etc. is done in cash. You might not like it, or agree with it, but that's the way it is.
You are unwilling, not unable, to pay a $2.50 ATM fee (or to deal with the "hassle" of paying someone in cash) to someone who is likely earning $2.50 an hour, and largely dependent on tips to survive.
(BTW, I hate the tipping culture in the US as well. I think all people should be paid a living wage. But I don't believe punishing the people who are already struggling is the proper way to make a point.)
Comment: Housekeeping is not paid $2.50 an hour. You're thinking of wait staff (in some states).  Check out the link in the other answer. I'm not saying they're paid enough, but they aren't expected to depend on tips for their wages like wait staff are.


Catalog Search Index failed and products list doesn't work

Question: Last Friday, I installed a new module (ERP embedded). Since this installation, the products list is empty on frontend. I'm using Magento 2.4.2 on apache2/php 7.4.24.
I try to reindex but I have an error :
->bin/magento index:reindex
Catalog Search index process unknown error:
Item (Magento\CatalogInventory\Model\Stock\Status) with the same ID "1" already exists.
A single product is ok with a direct URL rewrite. I checked if URLs rewrite existing for the category, it's ok.
I used bin/magento setup:upgrade to update the database, no error, all it's ok.
I cleared and purged cache. I restarted elasticsearch.
I tried to use a backup before the installation of the ERP module (the products list was ok), but I have the same problem, the products list didn't work! I suppose it's a problem with elasticsearch.
I forced search engine within/magento config:set catalog/search/engine elasticsearch7 and I watched elasticsearch status.
curl http://localhost:9200 return :
{
  "name" : "XXXXXX",
  "cluster_name" : "elasticsearch",
  "cluster_uuid" : "DTqi_5JvSAKmdPpmjJgmgg",
  "version" : {
    "number" : "7.15.0",
    "build_flavor" : "default",
    "build_type" : "deb",
    "build_hash" : "79d65f6e357953a5b3cbcc5e2c7c21073d89aa29",
    "build_date" : "2021-09-16T03:05:29.143308416Z",
    "build_snapshot" : false,
    "lucene_version" : "8.9.0",
    "minimum_wire_compatibility_version" : "6.8.0",
    "minimum_index_compatibility_version" : "6.0.0-beta1"
  },
  "tagline" : "You Know, for Search"
}

On Magento backend, connection with elasticsearch is ok.
What can I check? I don't have any more solution :(
I don't find something on StackExchange to help me.
Thank you very much.
Answer: Please try bin/magento indexer:reset before trying to reindex.


El Capitan Download would not resume

Question: I started downloading El Capitan and left my computer for a while, but it had gone into the sleep mode and the download was paused. But when I tried to resume it would not start even after restarting my computer.
Answer: I ran into the same situation as well. Just open mission control (4 fingers gesture), click and hold on the El Capitan icon and click remove (or delete). Then reinstall it on the mac app store. It worked for me. Hope it help.
Answer: I have tried to resume the download through the purchased tab, but still had the same problem (waiting...). But when I tried to download yosemite again the download of EL Capitan has resumed.

El Capitan Download would not resume


Do I need concurrent installations of Java Runtime Environment 32 and 64?

Question: Can I uninstall Java Runtime Environment 32 without any issues?  I have Java 7 update 51 and Java 7 update 51 (64-bit) both installed.  I want to uninstall the 32-bit version.  I am developing in Java, using the 64-bit JDK.
Answer: If you're developing pure Java applications (that is, no C/C++ code linked in) you can eliminate the 32-bit version. The two JRE (Java runtime environment) will work equally as well.
Answer: Per java.com, you only need the 64bit JRE if you plan on running a 64bit browser. Windows x64 systems by default have seperate 32 and 64bit versions of IE, so if you plan to use the x64 option (x86 is default), you need a 64bit plugin and JRE.
If you plan to run Firefox/chrome/whatever-other-x86-browser, just use the 32bit.
if you are getting a JDK for development determine what version is appropriate for your IDE or other development tools, and use it.
Answer: The 32-bit JRE is required to use the Java plugin in 32-bit browsers like Google Chrome and Mozilla Firefox (on Windows). For developing, just the 64-bit JDK is enough.


Burninate the [easter-eggs] tag

Question: An easter egg in some software is not a problem to be fixed. Asking what easter-eggs there are is a polling question, and unanswerable in many cases. Fortunately, not a common tag, but every question I've seen with it was off topic. I recommend burninating and black listing it.
Answer: I don't think the tag is nothing but a collection of off-topic questions.
I see several valid uses of the tag when I look at the questions tagged with it. Burninating and blacklisting it sounds overkill to me.

Burninate the [easter-eggs] tag


Ceph OSDs and journal drives

Question: I have a separate drive for each of my ceph OSD servers.  Each OSD host has 4 data drives.  Does one journal drive serve the 4?  Is the journal drive shared?  Should there be a partition for each data drive?
Answer: Journal/data separation
If you have just these four drives per OSD host, and all drives have similar performance, then the usual/recommended setup would be to have one OSD per disk (i.e. 4 per server), and each OSD would have its journal file on the same disk as the data.
Another popular (at least historically) setup is to have journals on separate drives that are optimized for write throughput and latency; usually SSDs, ideally SSDs with "power loss protection" so that they can acknowledge "sync" writes quickly without necessarily writing to the flash array (which can be somewhat slow).  In this setup it is common to share a journal SSD between multiple OSD (data) drives.  For example, our OSD servers have 8 or 10 spinning-rust drives for Ceph OSDs, and the journals are distributed over two SSDs.
Partitions
If your data and journal are on the same physical disk, I personally would put them on the same partition/file system.  Mostly because I would be worried that if they were on separate partitions, then there would be a lot of head movement when the OSD/file system alternates between journal and (background) data writes.  I'm not sure this is actually an issue, and on SSDs it certainly isn't.  In general, separate partitions give you some optimization opportunities, i.e. different file system parameters or even file system types, or no file system at all for the journal.  This comes at the cost of operational complexity, for example when adding or changing the size of a journal requires you'd need to repartition the disk.
In our setup with data on spinning disks and journals on (fewer) separate SSDs, we have a single partition per spinning disk (OSD), and a dedicated "journal" partition on each SSD; each partition contains 4–5 journals as files.  Our journal files are sized at 6 GiB each, so the journal partitions are 40 GB or so.
Caveat emptor
This setup has evolved based on a few years of experience and considerations of SSD lifetime and file system/SSD efficiency (latency, throughput).  It's not necessarily the optimum, but then it's a tricky area... OSD journals have a peculiar access pattern: write only to a circular buffer, with frequent "sync"s.  And SSDs can have large variations in (especially write) latency depending on usage (and controller and file system smartness); and latency peaks can be exacerbated by the fact that Ceph only ACKs a write when N (typically 3) writes have been committed to stable storage.  In general, I think this is still a little bit of a (dark?) science, and you definitely need to take the expected usage patterns into account, so take all recommendations with a grain of salt, especially these here.
Oh and everything I said is for the "classical" Ceph where the data is stored in a file system such as XFS/ext4/...  With the upcoming "BlueStore" these considerations may not (all) apply anymore.
Comment: Thnk you.  Don't the journal file systems have to be mounted (under /var/lib/ceph/osd/cluster-number/journal?)  Wouldn't this mandate that each have a journal on a different partition?
Comment: A journal is just a (single) file. By default, it will be under the OSD data partition, under the filename that you wrote. But you can also put that journal file elsewhere, e.g. on a filesystem backed by fast storage such as SSD. You can also specify a raw block device partition as the journal "file".
Comment: "Another popular (at least historically) setup is to have journals on separate drives" @sleinen why does this is not popular now. I thought having a separate ssd for journal is always better. Why not these days? (let's say if additional disk is not a burden and for data writes also separate ssds are used)

Ceph OSDs and journal drives


Electron blocking layer and hole blocking layer

Question: What is basically an electron blocking layer and a hole blocking layer in contrast to an electron transport layer or a hole transport layer? In terms of the bandgap, I think if the case is one of a staggered heterojunction with the material right of the junction having a lower conduction band edge, then the material on the left becomes electron blocking and hole transport layer while the material on the right becomes electron conducting and hole blocking layer. Am I correct or am I messing it up? In my diagram, if I am creating excitons in the material2 region, then I would assume material1 to be the electron blocking region and hole conduction region while material 3 would be the hole blocking region and electron transport region simultaneously. Is that the case?
Comment: A drawing would, not surprisingly, help a great deal. While the structure you are thinking of is clear to you, it does not come across clearly in just words. And, for heterojunctions you may need to specify both band offsets - you can have an electron blocking layer that is not a hole transport layer. But, beyond even this, these terms are applied in the context of a device structure, so are not uniquely defined.
Comment: @Jon Custer: Done editing the question.
Answer: If you are taking about p and n junction diode. In this section p type has electron deficient and it has positive charges and n type have negative charges. When you joint p and n type material than process of neutralization starts between holes from p type and electron from n type material. Positive charges from p type and negative charges from n type comes near to each other to become neutralized but they could not do so. And block further neutralization process of electron and holes. This is the depletion region or potential barrier of Diode. Hope it will help you.
Comment: Thank you for your reply but I 'm talking more about heterostructures than pn junctions.
Answer: Yes, the description is right. In a photovoltaic cell, where the terms Hole Transport Layer (HTL) and Electron Transport Layer (ETL) are often found, material2 would be the absorbing layer, material1 would be the HTL where holes are collected (but electrons blocked), and material3 would be the ETL where electrons are collected (but holes stopped).
However, the drawing is not correct: it looks like there is a fourth unnecessary material between material1 and material2 with the conduction band of the first and the valence band of the third.


How can you resize the icons in the Unity Dash?

Question: The icons in the panel are way too large for my preferences, how can you resize them?
Answer: With Unity tweak tool you can customize several properties. It is available through the Ubuntu Software Center or you can fire up a terminal and type
sudo apt-get install unity-tweak-tool

Answer: Open your Home Folder
Click on Edit -> Preferences
On tab Views
Change the percentage of Icon View Defaults to your preference ;)
Answer: I solved this with changing source code of unity and then i built it.
I think this is the only way, but it works.
You can follow: https://unity.ubuntu.com/getinvolved/development/unity/ (read carefully everything is perfectly correct and working, just read..)
When you downloaded the code and tried to build it, and it worked.
Change this line:

double const DEFAULT_SCALE = 1.0;

to

double const DEFAULT_SCALE = 0.75;

in file "~/code/unity/trunk/Dash/ResultRenderer.cpp"
Then delete the build folder (if exists) in trunk folder, and rebuild the code.
Building installing and everything else is described on the page i posted.
On my 15.4" notebook with 1366x768 resolution the 0.50 is too small for me.
This changes the icon and text size inside unity dash.
Good luck to everyone, hope that in newer wersion there will be option to scale up/down icon size in dash.
Answer: You can change them by opening the CompizConfig Settings Manager. Then go to the Ubuntu Unity Plugin. Change the tab to "Experimental" and modify the slider for "Launcher Icon Size"
If you don't have CompizConfig Settings Manager installed (not sure if it's installed by default on 11.04) then you can install  it by installing the compizconfig-settings-manager pacakage.
Comment: Sorry, but he means the Dash and not the launcher :)!
Answer: The unity dash icon cannot be resized. There is a bug open for six years and does not look like it's going to be addressed.
https://bugs.launchpad.net/ubuntu/+source/unity/+bug/815440


Benefits of Using Continuous and Strobe Lights Together for Studio Photography?

Question: Much has been written about the pros and cons of strobes vs. continuous lighting for still photography. I've recently seen YouTube videos showcasing the use of both types of lighting simultaneously, but primarily for special gel/motion effects. One exposure challenge is to ratchet down the output of your strobes enough so that they don't overpower the continuous sources. Other than these limited special effects, what are the general benefits, if any, of using both sources?
Comment: Where, when, and by whom was all the writing done? What does it opine?
Answer: You would appreciate strobes better if you lived the era of hot lights. When I was a boy helper, I hauled the lights upstairs and down and set them up and blew the fuses and ----. The poor subjects, under the hot lights overheated and some fainted. Then came the strobes, Still needed to haul them, but they did not over-heat the subjects.
Hot lights have the advantage, you know how the play on subjects. You get to see the effects of light and shadow "chiaroscuro". You get to see and feal the lighting ratio. Not so much with strobe. You can measure ratio with a meter, you can see how they play if they have a modeling lamp.
Knowing how hot lights effect the subject, I would go for strobes every time. As to a benefit, mixing and matching hot lights and strobe in the studio, I don't think there is any mix & match advantage that can't be worked out using strobe.
Let me add, I grew up with hot tungsten, modern LED is bright and a lot cooler. I have never used them, if they are cool running and comfortable from the subject's point of view, then likely they are the studio lighting of choice.
Comment: I'm far newer to this field, but by dint of my day job I get to see both in use. On location, trying to light an entire building interior [from outside] to look daylit even at night, they use 18KW lights, one at each window. You cannot stand within yards of these, they're like hot sun. On smaller sets, you can do it all in LED these days. Their downside is now only that they cannot pump out the massive spot/floodlight effect of the big 18k's, so you have to use them more selectively. They do still use smaller, 1k & up tungsten/halogen lighting indoors, but the LEDs are getting there.


What is the exact wing chord length and thickness for Boeing 747?

Question: I can't find this info anywhere and all they give me is the ratio. However, I need the exact/approximate values
Comment: The chord of a 747 wing (and the thickness) varies along its length. You'll need to be more precise about what you're looking for to get an answer.
Comment: I am looking for the approximate length and thus, the mean chord length or the range of chord length will be great.
Answer: In general, you can get good general dimensions from the Airplane Characteristics for Airport Planning documents (Boeing). These documents include the overall dimensions and everything relevant for the airport. This does not include the chord length though.
To get more accurate dimensions, you can download CAD drawings from Boeing. I did this for the 747-400 and the 747-8I and measured the chord length in three places along the wing:

As you can see, the chord length varies between 14.84m at the root and 3.70m at the tip (before the winglet). The wing for the 747-8 has been slightly re-designed:

While keeping its basic structure and sweep, the wing is thicker and deeper, holding more fuel, and wider with raked wingtips.

(Wikipedia)
The differences in chord length are rather small (possibly less than the accuracy of these drawings):
Answer: I estimate a 565 or 567" chord length where the wing meets the fuselage and wing-to-body (WTB) fairing, based on the Fuselage Station Diagram from the Structural Repair Manual:  https://static.rcgroups.net/forums/attachments/1/8/4/2/1/0/a5165653-56-img063%20-%20Copy.jpg
I would subtract 20" to account for the curvature at the leading edge where the WTB curves and smooths into the leading edge, unless you are going to accurately model that curve.
If you are making a model it'll be helpful to be aware of how the wing is constructed. The primary structure is the aluminum wingbox structure, which takes all the flight loads and spans from wingtip to wingtip, including the center wing section/tank (which is hidden inside the WTB and fuselage).
On a real Boeing this wingbox structure is usually a darker color (except on United Airlines and maybe Singapore and/or Thai and on 747-8s) because it is painted with corroguard.
The leading edge and trailing edge are attached to the wing box along with the flight controls, flaps and everything else.
Over 20 years ago I assembled 747-400 center wing sections and can tell you that a 6' person can stand up inside the first bay of the center wing tank (CWT).
After TWA800 happened the media came through our work area and took pictures:  Here is a photo showing a guy I worked with inside the CWT:
https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Ftse3.mm.bing.net%2Fth%3Fid%3DOIP.AOrngW4VMwMG65-dPj3dgwHaGo%26pid%3DApi&f=1
Here, you'll like this too:  https://static.rcgroups.net/forums/attachments/1/8/4/2/1/0/a5165657-231-img067%20-%20Copy.jpg
Here is NASA's 747 with the wing removed clearly showing the wing box: https://s.hdnux.com/photos/27/13/50/6076974/3/1200x0.jpg
Here are all the photos at rcgroups.net , including more of the 747:
https://www.rcgroups.com/forums/thumbgallery.php?do=threadgallery&t=1734624
Are you making a CAD model or a physical model?  Is it a flying R/C model?
(I just signed up here with my google account to answer this question, so I'm not sure how I will be alerted of your reply, but I assume that I will be).
Matt in Seattle