Can a single-threaded program be made to use multiple cores?

Question: The title says it all: is there a way to get an older program designed to use a single CPU core to use multiple CPU cores?
Comment: No, not possible.
Comment: If only it was that easy..
Comment: What if there were a program that 'emulated' a processor (like maybe a vm?) but took your multi-core CPU and emulated a single-core CPU with much more processing power per thread? Is that possible?
Comment: Who will manage the synchronization between multiple threads then, because order matters.
Answer: Unfortunately, a legacy program written for a single CPU cannot be forced to use multiple CPU cores.  The usage of multiple CPU cores requires multiple threads, which need to communicate with each other while ensuring that race conditions and other problems do not occur.  An older application cannot be made to use more than CPU core unless it is rewritten to do so, and only if the nature of the application allows it to be parallelized.
Comment: It's also worth noting that some applications simply can't be rewritten to take into account multiple cores. It mostly depends on how parallelizable the process is. A simple example of non-parallelizable process would be human reproduction: One woman can make one child in 9 months. Nine women can make 9 children in 9 months, but you can't use 9 women to manufacture a single child in one month.
Comment: In principle one could write a program to analyze another program and attempt to parallelize it. That said, even very limited "easy" versions of this problem have been generating Ph.D. dissertations for the last couple of generations and progress has been slow. The full problem may very well be AI-complete.
Comment: Great, thank you all, you made me grion with your Women and birth example, especially when you talk about manufacturing :D
Comment: what if a program has a bunch of independant mathematical operations that are later used for eachother? maybe a second thread can parse the program,  hmm I do no know what I'm saying. If a thread could parse assembly.. "do expensive operation here, then do second expensive operation on this that the first expensive operation doesnt touch" okay I'll put one expensive operation on one thread, one on the other, then synchronized put them back on the main thread.

I suppose an entire program would have to be pre-parsed to identify independant expensive operations.
Answer: What is your goal with it?  Increased performance?  Sadly applications that are designed to make use of only 1 core will not make use of more.  Thats what this talk of "multi-threaded" applications are all about.
Answer: There are at least three techniques for exploiting multiple processors in a program designed for using a single core. The most straightforward of these techniques is to use libraries and system code that uses multiple cores or can execute at least partially in parallel with the application code. Garbage collection is an example of functionality that can be parallelized and might be possible to do in parallel with application execution. Even without automatic memory management, there is some potential for parallelism in memory deallocation functions because the memory allocator may have some work to do beyond simply marking the section of memory as available.
A second technique is binary translation. While this might be considered "rewriting the application", it is done by software and without access to source code. Producing thread-level parallelism seems not to have been the main goal of most research and development using binary translation (which often concerns running legacy code on a different ISA, exploiting ISA extensions or optimizing for a particular microarchitecture, and using dynamic information to provide higher quality profile-guided optimization), but the potential is obvious.
A third technique is speculative multithreading. Currently no processors (that I know of) support hardware-managed speculative multithreading. However, with the introduction of hardware transactional memory, having a runtime system implement such becomes somewhat more practical because the HTM can be used to detect conflicts in memory use. Software-managed speculative multithreading would typically involve some binary translation, but its speculative nature justifies considering a separate technique.
The practicality of these techniques is limited by costs associated with existing systems (including the cost of communication between threads and of spawning threads), by the limited parallelism that they can exploit, and by the limited return on investment (important applications that can be beneficially parallelized are likely to be rewritten, many applications would benefit relatively little if at all from such techniques (especially with power/thermal limits allowing a single core to run at a higher frequency than multiple cores), and the development costs are significant). Yet these techniques do exist and it is theoretically possible to use multiple cores with an application designed to use a single core.
Answer: No it can't be. A program is explicitly written to use multiple cores. It is not trivial to do the job in multiple cores. It requires synchronizations of all threads. Like one throws the ball, the other catches, one polishes the ball, one cleans, one check the ball whether it has good amount of air in it. Now imagine each character as running in a thread independently of each other. Someone tries to catch the ball when its not thrown. Or someone tries to polish the ball when it is being played. Or two characters trying to catch and throw the ball simultaneously. There are so many ways to crash. So programmers need to carefully redesign a single core application so that it can take advantage of multiple cores.


Adding an outlet to a hall closet

Question: I'd like to add an outlet to a 1st floor hall closet where I store tools.  The water meter for the house is in this closet, but nothing else (e.g. no water heater, furnace, etc.).  The closet is roughly 8'x 4'. The outlet will be used to charge batteries for drills, vacuums, etc. -- so very low amperage.  I'd like to wire the outlet into a dedicated 20A circuit I have for a sump pump. I don't have a sump pump and don't anticipate getting one, so the outlet is going unused.  The sump pump outlet is close to the closet, so tapping into it would be very convenient.  I plan on making the new outlet 20A and running 12/2 cable to be consistent.  Any concerns with this approach?
Comment: This could be done but in my area if used for a sump pump non GFCI it must be a dedicated circuit. If you put a GFCI outlet at the sump pump location then I would see no problem with using this supply for your needs.
Answer: Sump pumps have usually been put in on dedicated circuits, possibly to get around the GFCI requirement, but you say you don't have a sump or expect to ever. Based on what I can find in the National Electric Code, I would say it is okay to use it, but you should check local ordinances. Your wiring plan is fine, properly sized wire for the circuit breaker and probably oversized for the charging equipment you expect. NEC 210.8(A)(4) includes crawl spaces in the GFCI requirement, but if your receptacle is going to be in a closet above grade (not in an unfinished portion of a basement) you wouldn't need GFCI there.
If you decide to also leave the sump receptacle in place, in case you need to plug in a light or something in the crawl space, it should be converted to GFCI, but to avoid confusion I wouldn't protect the closet one from there. In other words, use the terminals marked on the back of the GFCI "Line," and do not use the terminals marked "Load." That way if it trips it won't turn the closet receptacle off as well.
Answer: The only issue I would anticipate is that the sump pump outlet is probably not arc fault protected.  Depending on your local code requirements, you are probably required to have arc fault protection on a circuit supplying receptacles in a closet.
Comment: Thanks. I forgot to add that the sump outlet is in a crawl space but not a GFCI. I recently had an electrician add an outlet down there for a tankless water heater and he did not use a GFCI, if that means anything.

Adding an outlet to a hall closet


Examples showing nodeJS's strengths

Question: I'm getting interested in nodeJS and the idea you can run JS on the server, so just wondering if anyone has some examples or can explain the potentialities of nodeJS (documentation on the site is not big)
Answer: I'm programing an app with nodejs right now, I can say that one of the biggest advantages is the performance. You can usa a documental dabase like mongoDB, and you'll have a turbo APP.
There is a web framework like Sinitra for Ruby, the ExpressJS, it's very simple to use, and does great to small apps. http://expressjs.com/
For database, mongoDB is very simple to use and works great with javascript, since you can read and persist JSON objects. http://www.mongodb.org/
To use mongoDB, there is the Mongoose module, it will abstract the usage and provides the connection.
https://github.com/ciaranj/mongoose
Here is a tutorial to get started: http://howtonode.org/express-mongodb
Answer: If you want to play with cutting edge tech, then a really exciting avenue is nodejs + current draft specs of HTML5 WebSockets. Rob Hawkes' Rawkets is a great demo of this -- a realtime multiplayer rocket game (see Github source), that uses an NPM module called websocket-server, making it insanely easy to do realtime games in the browser. There are only 3 browsers that support WebSockets right now though: Chrome, Firefox and Safari. And I had to specifically enable it in Firefox 4 and 5 due to a security issue with the design of the spec as it stood. Firefox 6 implements the protocol that's fixed. There's a programmatic way to check whether WebSockets is implemented too

Examples showing nodeJS's strengths


Li-ion battery cell balancing statistically unnecessary when many cells are in parallel?

Question: Lithium ion batteries packs need to be balanced because of a small random voltage difference for each section in series, that may cause the voltage levels in a pack to diverge over time, right? So if you had a large number of cells (<40) in each series section wouldn't it be unnecessary to have balancing circuitry as the voltage difference of each series section would be extremely small due to the large sample?
Comment: The way I am thinking: you have a bunch of parallel cells in a section. Several sections are then placed in series. Balancing is not required because the average voltage of each section is always very similar due to the large amount of cells in parallel.
Answer: Your title mentions cells in parallel yet the text talks about cells in series, that's confusing. I just answer both cases:
In case you mean cells in parallel:
No, cell balancing does not work like that. What matters is the difference in voltage between individual cells.
Using a large number of cells does not guarantee that the cell with the lowest voltage will have a higher voltage, closer to the average. So when that cell is connected it will still be charged (with a large, possibly damaging current) by the other cells.
Any time two (or more) cells are about to be connected in parallel their voltage must be similar to prevent large current to flow. This is done by balancing. This applies to any number of cells.
In case you mean cells in series:
No, cell balancing does not work like that. What matters is the difference in capacitance of the individual cells.
When one cell is almost empty but the other cells are not then you cannot keep using the battery pack as that empty cell will then be reverse charged and it will be damaged forever. So discharging has to stop.
The same is true for charging, when one of the cells in the series is nearly full the charging current through it has to be lowered to not overcharge it.
Using a large number of cells does not guarantee that the cell with the lowest capacity will not be over charged/discharged.
Any time two (or more) cells are about to be connected in series the voltages of all cells need to be monitored to prevent over charging/discharging.
Comment: The question is ambiguous -- the title says "many cells in parallel", but the body says "large number of cells in each series section", which may or may not mean the same thing. I think the first version of your answer was closer to the mark.
Comment: Indeed, only noticed that now.
Comment: I don't think you're right in the second sentence: "any time two (or more) cells are about to be connected in parallel their voltage must be similar to prevent large current to flow. This is done by balancing. This applies to any number of cells." I have never seen cells in parallel that have balancing circuitry. I understand that when initially connected in parallel the cells would need to have equal voltages though.
Answer: When several lithium cells are connected in series, it is the variation between series sections that requires balancing to be used. The problem with leakage and charge efficiency is that differences in these have a cummulative effect, and battery imbalance grows with each charge/discharge cycle.
I understand that you think that making each series section out of many cells in parallel would tend to even out the variation between those series sections.
However, 'tend to even out', and 'reduce to such a low level that it's not an issue during the expected lifetime of the pack' are very different things.
In the worst case, each series section will be as unbalanced as each individual cell. So there may be no improvement.
In the 'typical' case, you could statistically expect sqrt(number_of_cells) less variation in the parallel ensemble than for individual cells. For 40 cells, that's about 1/6th. So if you relied on this improved balance, you could typically cycle your cells 6 times more often before they became as unbalanced as a single series string. Doesn't really sound good enough improvement to me.
In the matched case, where you measure all the cells for capacity, internal leakage, charge and discharge efficiency, over temperature don't forget, and select the cells so each series section matches on all parameters, unfortunately those parameters change with age. Maybe you'll get 10 or 20 cycles out of the pack before differential parameter drift causes them to become unbalanced.
If you have series lithium cells, actively balance the charge between them.
Some people wonder why we need to balance lithiums, when we never needed to balance lead or nickel chemistries. The answer is that lead and nickel can be overcharged safely (as long as certain limits are observed) which naturally balances them. Unfortunately, there are no conditions that will allow the safe overcharging of lithium chemistries, overcharge rapidly destroys the cell.
Comment: Thanks. By the way, i was thinking more in terms of: reduce to such a low level that it's not an issue during the expected lifetime of the pack
Comment: I know you were thinking that, to avoid needing balancing. It reminds me of the joke about the watch with a lifetime guarantee. Just before it breaks, a sharp spring comes out and slashes your wrist. Unbalance in a lithium battery ends its life in a very short time. Even the best matching you can do between cells will result in only a few 10s of cycles, when you can expect 100s of cycles from an actively balanced battery. When you don't use active balancing, the cell stays balanced for life, its life.


UWB circular antenna: input impedance (Zo= 50 Ω)

Question: I'm having difficulty with the line input impedance of the circular planar antenna signal. Its impedance is 117 ohms and the correct is 50 ohms, I am not able to lower the value. I made modifications to the input increasing the line width and also made an impedance transformer. When I get it down, the whole process on the antenna I made is impaired. Example: reflection coefficient is lost, surface current loses efficiency and also its power and directivity. Please can someone help about this.
Answer: An impedance of 117 Ohms sounds pretty reasonable for a particular point in the band, it translates to a reflection coefficient of -8 dB or so. I don't think you should be optimising it further yet.
UWB antennas are a compromise, intended to work over a very wide range of frequencies.
To judge its performance you need to analyse it over its full range of frequencies, 2 to 10 GHz or so, and look at the reflection coefficient over the whole band. Generally these shape of antennas work well enough directly at 50 Ohms without a matching network. Using a simple transformer like a quarter wave line of a higher impedance, will help one frequency but hurt others.
To tune the antenna, try adjusting the shape and size of the blob, especially its distance from the groundplane and its curvature near the feedpoint.
If you're able to change the shape - there are many design papers published about these, try searching for UWB in the IEEE APS transactions, or just on google.
For example, my first hit is this paper which shows the following antenna and its reflection coefficient:

Which indicates that the impedance in your simulation is pretty typical of UWB antennas of this type.
Comment: Hi, thanks for the scientific article, so this part you mentioned, every 2 to 10 GHZ frequency path really has to be a 50 ohm impedance match across the board. But when I manage to reach that value, everything ends up being horrible, an example I gain directivity running from the surface.
Comment: I made two antennas, one that I made with my data and the other that is reproduced in the scientific article. Incredible as it may seem, the reproduction of the scientific article with all the data still remains a value close to 112 ohms. By logical frequency level in microwave, the impedance of 50 ohms. I really don't know what the mistake is? Please I need guidance.    https://www.researchgate.net/publication/322855724_Design_and_Performance_Analysis_of_UWB_Circular_Ring_Antenna_with_Defected_Ground_Structure?fbclid=IwAR1SJL7QbEfVME4wZbU0i-UzSTFmjvUkXKqn1IDwXh0rgcLVtCPzd9gv-00
Comment: @lufer but it *is* matched to 50 Ohms, just not exactly 50.  117 is very close to 50 in this type of antenna, about -8 dB reflection coefficient. You are doing OK there, similar to the antenna in the paper. You should simulate over frequency, perhaps add your graph of reflection coefficient to the question so we're not just talking about one number at 7 GHz.
Comment: Sorry, but I'm finding contradictory information, the more I try to understand what's going on, the more I get confused. Because when you handle with microwaves the input impedance has to be 50 ohms, which I understand that Zref refers to what I understand in the CST means that it is real impedance that is on the line at that moment. I will send the images.    https://i.stack.imgur.com/uXJnn.png
Comment: It looks like you need to get some help driving CST. You are free to plot the real part of Zref, but it is a constant you choose, so not an interesting graph. You are also free to change Zref to any value. But why not leave it at 50 Ohms? There's no reason to change it, you just get strange reflection coefficient graphs.
Comment: I'm sorry, but a lot of your explanation can't understand, I don't know if it's because of the translation (I'm a foreigner).
Could you explain it better?


Switching time of a multiple input switch

Question: I basically have two switches
Both switches will be pressed simultaneously in different order
I want to know which switch was pressed first
Comment: `simultaneously` and `different order` are mutually exclusive ... you either press them at the same time, or you press them sequentially ... you can't do both
Comment: Please include in your question a description of what exactly is your problem with doing that. You can edit your question (this information belongs into the question, not in the comments)
Answer: Use External Interrupts is the short answer.
Longer version:
You probably want to make a buzzer system like what in family feud game show.
I assume you are using Arduino UNO/MEGA and or having experience with programming.
1/ Use INT0 and INT1 for button 1 and button 2.
When an interrupt is raised, the mcu jumps to a specific address to run the interrupt service routine. INT0 and INT1 vectors are pointing to two distinctive addresses to run 2 different functions. For this, mcu takes the least amount of CPU clock to capture which button press first.
2/ Use PCINT vectors which is PinChange Interrupt. But personally I prefer to call it PortChange Interrupt.
There are 3 PinChange interrupt vectors PCINT0, PCINT1, PCINT2 to run 3 distinctive service routines. But this kind of interrupt doesn't know which pin is changed.
So inside the interrupt service routine, you have to check for that specific pin. You can do this the arduino way digitalRead(button1) or capture the whole port register, ie. PORTB, PORTC or PORTD.
In a nutshell, PORTB holds values of digital pin 8 to 13 while port D hold values of digital pin 0 to 7 and PORC for A0 to A7.
You can shave off some CPU clocks (3-10 clocks probably) by put 2 buttons different PCINT vectors. So that each button still triggers distinctive function.
In 3 cpu clocks (or around 180 ns) a lot of things may change and you may not get the correct result.
3/ Polling in main loop()
This is the worst way to do it. Nevertheless, it still gives good result.
if (digitalRead(button1)==LOW) {
// do something
}

if (digitalRead(button2)==LOW) {
// do something else
}

Answer:
The simple version: check continuously for the state of the digital inputs the switches are connected to. When one is HIGH that is the switched pressed first.
The intermediate version: check the 'blink without delay' example to make sure you don't get too many false positives.
The advanced version: use interrupts when one of the two switches gets 'HIGH', using the 'blink without delay' to prevent false positives.

If you want to know if both are pressed at the same time, but one is pressed first, use variables to keep track on it.
like two variables:
bool button1Pressed = false;
bool button2Pressed = false;

Set them accordingly (depending on which of the 3 possibilities you use). Then when you know a button is changed, you can easily check the booleans to know which was already pressed.
Or you can use an enum that combines the state of both:
enum EState { ALL_OFF, BUTTON_1_PRESSED, BUTTON_2_PRESSED, BOTH_BUTTONS_PRESSED };

EState buttonState;


The Mac won't let me import photos from my iphone

Question: I am trying to import my photos from my iphone to my mac and even though i already put trust this computer, the mac insists that i haven't done it yet. i have done it many times and its still not working. Any idea of how to solve this?
Comment: What version of macOS are you using, and what application are you trying to import the photos into? One thing to keep in mind is you have to unlock your phone when the trust message appears.
Comment: I am using the Photos app on a MacBookPro and i already put trust while it was unlocked. Still nothing
Comment: Thank you for the advice from above comments. Resetting my Location and Privacy and pressing Trust when prompted on my phone actually fixed the problem of uploading my photos from my IPhone 6 to my IMac Computer. Thank you again, this advice was very helpful.
Answer: On your iphone, go to Settings > General > Reset > Reset Location & Privacy.
Plug in your iPhone via the USB to your mac.
On your iPhone when prompted press "Trust".
You should now be able to import.
Comment: This fixed the problem I had been having with an iPhone 5 running iOS 10.3.3 syncing to a MacBook Pro running Mac OSX 10.9.5. I'm intrigued to know why the problem appeared and why the fix worked, but thank you anyway.
Comment: This totally works but one has to wonder why it's needed at all, after **months** of using a specific macbook and a specific iPhone together, without any issue.
Answer: Since you haven't specified the version of macOS you're running, this advice will be somewhat general in nature.
On the Mac there are a number of ways to import photos. You don't explain how you've tried to import them, but have you tried using the Image Capture app or either the iPhoto and/or Photos apps (depending on what OS you have installed) instead of what you normally try?
[EDIT - Sometimes trying a different approach will trigger the Trust computer prompt and this will be accepted/remembered for next time]
These apps can be found within your Applications folder. The one you use will depend on how you want to manage your photos:

Image Capture provides a way for you to just import your photos to your Mac's hard drive to access and use as you wish. By default they will import to your Pictures folder, but you can select other locations as well as create subfolders.
iPhoto and/or Photos are apps that not only import your photos, but allow you to manage and organise them into albums, produce books, etc.

Regardless of the option you choose, all these apps will recognise your iPhone when it is connected via USB to your Mac. You need to just select the device from the app and import the photos.
These options are separate to iTunes and, in effect, just treat your iPhone as a camera.
EDIT
[This edit adds info about dealing with the 'trust computer' issue]
If trying one of the 'other' methods listed above still doesn't work for you, then the trick may be to get the prompt for the iPhone to trust the computer to pop up instead. You can try:

Turn off your iPhone
Connect the iPhone to your Mac via USB
Open iTunes
Switch on your iPhone
iTunes should then prompt you about the iPhone trusting the computer (instead of the iPhone prompting you)
Confirm that you want to trust the computer
On the iPhone prompt that follows, also trust the computer

Hopefully the next time you attempt to use image capture/iPhoto/Photos to import photos you won't have a problem.
However, if you do still have a problem, you can also try resetting your iPhone's Network settings. You do this by:

Navigate to Settings
Tap on General
Swipe up and tap on Reset at the bottom of the screen
Tap on Reset network settings

Keep in mind once you've reset your Network settings you will need to reenter any WiFi passwords again you normally connect to.
Comment: Photos requires the computer to be trusted by the device just as iTunes does. It knows that iPhone is not just a camera.
Comment: @tubedogg Thanks for picking up on that. I've edited my answer to be somewhat more thorough.
Comment: Thank you for your answer. i already tried all of your options but its still not working. :( I want to try resetting network settings but im afraid i will lose something. Are you sure it is totally safe?
Comment: Yes. Resetting Network settings is totally Safe. More specifically, what this does is reset WiFi networks and passwords, cellular settings, and VPN and APN settings that you've used before. For the majority of people all they will notice is having to reconnect to WiFi networks again. This option is used usually because of problems connecting to the internet, either via WiFi or cellular, but it also helps for less common issues like yours, problems accessing voicemail, etc. I can't guarantee this will fix your problem, but I've seen it work for others.


Does disabling iMessage read receipts stop me from receiving them?

Question: When I turn off Send Read Receipts in iMessage, does that disable me from receiving read receipts from others as well? I have noticed that I only receive read receipts when I have the feature turned on.
Comment: are you not recieveing iMessages or others read reciepts?
Comment: Seems like an odd thing since most phones I've seen work just fine and receive messages without regard to whether read receipts are sent or not. Have you tried any of the normal things (reboot / restore / restore+set up new) to rule out simple software corruption?
Comment: Graeme - read receipts. I edited the question to reflect it. @bmike - I've tried rebooting. It's not a big enough deal for me to restore though lol. Just was curious about the functionality
Answer: The functionality is for messages to get delivered via SMS if that is enabled and iMessage is disabled or not available for the sender.
iMessage should / is designed to receive messages whether or not you are sending back read receipts as long as you and the recipient are on devices that match in Apple's database of recipients that are iMessage capable.
Something else is up - it could be related to the switch (as software corruption can act in weird ways) but it's certainly not the typical behavior.
Comment: I hadn't noticed that effect, but I could easily see how that decision was made to suppress all status messages incoming and outgoing with that one switch. I'll have to check it out with someone that I know sends them.
Comment: Thanks for the response. I think you misunderstood the question though. I'm receiving iMessages just fine. I just don't get the notification saying that the receiver read my message if I have "Send Read Receipts" turned off.
Comment: @bmike Do you mean that the "..." (http://apple.stackexchange.com/q/35188/6533) will be visible regardless of whether or not "Send Read Receipts" is switched on or off?
Comment: I was hoping to convey that my suspicion is that "..." suppression is tied to the sending of read receipts. There isn't a setting to say, don't let my chat companion know if I'm typing, so it either always shows or only shows when read receipts is enabled (and functioning correctly presumably)
Answer: Read receipts come to you whether or not you have the feature enabled. It shows up under the message you last sent in place of the word "Delivered" and it just says "Read" ...after a period of time it tacks on the time it was read too.
Answer: ok, Ian did pretty good, but I think he could have been a bit more clear with it.
Read Receipts tell the person who sent YOU a message, if you read their message or not. If YOU are SENDING a message, it does NOT matter if YOUR read receipt option is on or off. If the person you sent the message TO have read receipts ON, then directly under the message you sent, if will tell you if they read your message or not. If the person you sent the message to has the option turned OFF, then you will not know if they read your message or not.
So if you turn off read receipts, then people who sent you messages will not know if you read them yet. That's all it does.
Comment: Lol thanks. I know what the INTENDED functionality is. But I think there are some latent functions as well. I could be wrong though. Just wanted to know had anyone else seen this particular behavior.
Comment: well, not yet I haven't, but most of my friends are content with using me as a guinea pig for IOS 5 while they keep the relatively bug-free IOS 4, just in case the 5 messes up, so i don't really have a use for iMessages yet.


what is the meaning of "escalation path"?

Question: here's the context:
There are clear escalation paths, a clear
management chain, and there is information being broadcast to them to help them do
their jobs better and more efficiently.
Comment: The meaning is "a clear management chain". A task would be escalated when the person working on the task does not have sufficient permissions to proceed any further.
Answer: In the sentence that the OP provides, the phrase 'escalation paths' refers to chains of higher-ranked individuals that an employee can consult to resolve a problem that they don't have the power or resources to address themselves.
For example, a construction worker might encounter a buried archaeological site while digging a foundation.  That worker doesn't have the authority to destroy such a site, so he or she escalates the problem to the next person in their 'escalation path', who is their foreman.  The foreman also lacks the authority to resolve the problem, so they escalate it to the site manager.  The escalation path may extend all the way up to the construction company executives who have the authority to contact the government agency responsible for handling archaeological sites, and only those executives can arrange for either a variance to the construction permit to destroy the site or delay the project to allow for the site to be inspected and cleared by archaeologists.


Radio frequencies, what are the limits?

Question: What is the correct range of frequencies for radio waves? Wikipedia's article on radio waves states that all frequencies below 300 GHz are radio waves, while the article on the radio spectrum states the upper limit is 3 THz. Additionally, the article on microwaves states that microwaves have frequencies between 300 MHz and 300 GHz and radio frequencies are below 300 MHz. Why is there such inconsistency? What is the correct frequency range?
Comment: Are these our "limits" we are pushing on nature? Does nature have it sorted?
Comment: And 50 Hz is a "wave" ... point of view of "terrestrial" atmosphere ... 40 000 km wavequide (?).
Answer: Radio waves and light waves are both electromagnetic (EM) waves. Visible light is physically the same thing as radio, just at a different frequency/wavelength. All EM waves are a coupled electric and magnetic field propagating through space; it just so happens we can see some of them with our eyes, feel some as heat, get radiation sickness from others, and some pass through our body entirely unnoticed. Since they have such different effects which are dependent entirely on their wavelength, we categorize them into different groups.
Radio waves are EM waves we can create by oscillating an electric field in a conductor. Through careful control of the exact electric field at any given instant, we can encode and transmit information through these oscillations.
Visible light, along with infrared and ultraviolet, is produced electrically through high heat (incandescence), fluorescence, high voltage gas discharge, or more recently LEDs. We use them for lighting, heating, fiber-optic communication, disinfecting (in the case of UV), among other things, but with current technology we can't really control its frequency through modulation like we do with radio waves. Generally, work in these frequency bands falls under the umbrella of 'optics'.
And between them lies the terahertz gap. Above about 1 THz ('submillimeter wave', 0.3 mm) we lack the technology to reliably produce and transmit radio waves; below about 30 THz (10 μm), far infrared optical detectors are not really feasible.
(Far UV, x-rays and gamma rays, called 'ionizing radiation' as their high energy can strip electrons from atoms, can be produced through other means, like x-ray tubes, radioisotopes or high-energy particle collisions, but are not, to my knowledge, used for communication.)
In short: the maximum frequency for a "radio wave" is whatever we can produce using an oscillating, modulated radio transmitter. As technology advances, the maximum frequency will no doubt continue to increase.
Comment: @YPOC: yes, and not "in theory", but it would be exactly like that. If you have any doubts, please keep re-reading first paragraph of this answer.
Comment: So if I had a radio transmitter and turned the frequency *all* the way up, it could in theory emit light?
Comment: Literally light, if you can  justfigure out the minor technical challenges underlying "turn the frequency up".
Answer: There is no standard I am aware of that defines what is considered the radio portion of the electromagnetic spectrum. There is no correct frequency range. There are only conventions that often exist only for historical reasons. Sometimes these conventions are useful because they tell us about the kinds of approximations that can be used in analysis and the enabling technologies that may be used.
For instance, microwaves and radio waves are frequently lumped together these days (as in the wikipedia article you linked) as the underlying technologies used to produce them are similar, most often solid-state oscillators. The optical spectrum is often talked about as separate, however, because thing's like lasers and LEDs are used to produce it, and the wavelength is often much smaller than the structures the electromagnetic radiation is interacting with (the same can certainly be true of longer wavelengths but it is a less common situation)
It is all electromagnetism. Any labels we put on the spectrum are arbitrary and different groups of people have labelled it in different ways.
Answer: If you read one line beyond the table where the claim that "microwaves have frequencies between 300 MHz and 300 GHz and radio frequencies are below 300 MHz" appears, you find:

In descriptions of the electromagnetic spectrum, some sources classify microwaves as radio waves, a subset of the radio wave band, while others classify microwaves and radio waves as distinct types of radiation. This is an arbitrary distinction.

Radio frequencies, what are the limits?


Could one shape pheonix belt and bind manticore belt to the totem chakra at the same time?

Question: Both of these soulmelds take up the waist body slot but I don't know if that matters since they're both soulmelds and the pheonix belt is only being shaped, not bound.
Answer: Yes.
Look in Magic of Incarnum, page 38, for the feat:
Double Chakra

Two of your shaped soulmelds can occupy (and be bound to) that chakra simultaneously.

Note: It requires Meldshaper Level 9th.

(Remember - What you want to do requires the feat mentioned above. Credit: Miniman.)
Comment: You should mention the normal case, without the feat. The Totem is a weird case here
Answer: The meldshaper usually can't employ a phoenix belt and the manticore belt simultaneously
Magic of Incarnum in the chapter Soulmelds under Shaping Soulmelds under Meld Selection says that

[T]wo soulmelds can't occupy the same chakra (with some exceptions). (50)

To realize a soulmeld's benefits, the soulmeld must be shaped (the soulmeld then occupying a chakra) or bound (the soulmeld then occupying both a chakra and a magic item slot).

Those exceptions
Here are some of the exceptions mentioned in the quotation above.

The general feat Double Chakra has as its prerequisite a meldshaper level of 9 and says that

When this feat is selected, choose a chakra to which you can bind soulmelds. Two of your shaped soulmelds can occupy (and be bound to) that chakra simultaneously. This counts as two chakra binds. (38)
A totemist who binds a soulmeld to his totem chakra has a soulmeld that occupies—instead of the totem chakra—another chakra:

When a totemist wishes to bind a soulmeld to her totem chakra, she must choose a different chakra for that soulmeld to occupy. Regardless of the chakra occupied by the soulmeld, however, the totemist can bind it to her totem chakra. This is an exception to the normal rule that a soulmeld can only be bound to the chakra it occupies. (51)

While this doesn't allow a totemist to have two soulmelds occupying the same chakra, it does allow a totemist to bind a soulmeld to one chakra and have that soulmeld merely occupy a different chakra. It's strongly implied that the totemist can pick any chakra to be occupied by his totem-bound soulmeld, but I can imagine a DM mandating a totem-bound soulmeld occupy one of the the soulmeld's default chakras (e.g. the brow chakra for a basilisk mask).
For example, under most readings a totemist could bind a manticore belt to his totem charka and pick the manticore belt to occupy his crown charka; simultaneously, the same totemist could bind a phoenix belt to his waist chakra.
The totemist's special totem chakra (double bind) says

At 11th level, you gain the ability to bind a single soulmeld to your totem chakra and to another chakra at the same time. You gain the special benefits of both chakra binds. (30)

While this, too, doesn't allow a totemist to have two soulmelds occupying the same chakra, it allows a totemist to bind a soulmeld to two different chakras if one chakra is his totem chakra.
Obliquely, this also means the same soulmeld can't usually be bound to more than one chakra (e.g. once a basilisk mask is bound, a meldshaper can't bind a basilisk mask to a different chakra until the meldshaper unbinds the mask from the first chakra.)
Just in case you were wondering, the section Soulmelds under Magic and Incarnum says that

two of the same soulmeld can't be shaped on the same character simultaneously. (52)

So no doing that, either.
The prestige class incarnum blade at level 5 gains the special dual chakra binding (MoI 123), but such a character can only bind his special soulmeld blademeld to two different chakras, therefore receiving the benefits for having done both.

I am unaware of further exceptions.
Comment: Huh, I would not have read it as strongly implied that any chakra is available for the totem's chakra-occupation, though you are correct (to my surprise, though considering this is *Magic of Incarnum* it's no great surprise) that it doesn't say it's limited to those the soulmeld uses. Still, the descriptions of individual soulmelds' totem binds describes them as taking a particular place much of the time.
Comment: @KRyan Admittedly, I'm headging a bit with *strongly implied* as that's my reading of it because, while it doesn't *say* that, it also doesn't say *A soulmeld bound to the totem chakra must occupy one of the chakras the soulmeld usually occupies*. Which would make sense, obviously ("I got a *blink shirt* on my forehead! Awesome!"), but it *also* makes senses that the iconic superpower of the totemist is allowed to break even unwritten rules.


How do I apply potion effects to a player wearing armor with a special name with command blocks

Question: I am making special classes for my server, and I want to give someone underwater breathing whenever they are wearing a helmet named scuba. How do I do this with command blocks?
Answer: What you could do is /testfor a player with a helmet with a custom name scuba.  Test for the slot number they have it in, (helmets are 103)  This command should do all that:
<code>/testfor @p[r=2] {Inventory:[{Slot:103b,tag:{display:{Name:"scuba"}}}]}
</code>
Hook it up to a clock of your choice and if the /testfor command reads true then have a comparator ready to activate a sticky piston that pushes a redstone block to activate the command
<code>/effect @p minecraft:water_breathing
</code>
When they leave your set radius or remove there helmet the sticky piston will deactivate pulling the redstone block activating the command
<code>/effect @p clear
</code>

This is a list of the inventory slot numbers.

The Youtuber Dragnoz also has a great video on how to do things like this.


How can I get Sokkia total station .RAW file data into ArcGIS

Question: I have a .raw file from a Sokkia total station.  I want to view the data in ArcGIS and create contours from this data.  Can anyone help?  The survey analyst extension is longer supported in ArcGIS 10.1 so I'm not sure where to begin...
Comment: I believe Copan (which is free) can do what you need. Please post a sample of your raw data so i can confirm. Use the "edit" button, above (between "share" and "flag") and paste it in as though it were code (it *is* code). I can give a detailed answer...
Comment: I'm not sure if this counts as a duplicate or not. http://gis.stackexchange.com/questions/1890/how-do-i-import-total-station-data-gsi-files-into-arcgis covers a different Total Station format and the answer was to use an extension no longer available. I don't know if the questions should be merged or remain separate because of the different file type and to encourage new answers/alternatives to the original given software changes.
Comment: @ChrisW - Leica GSI and Nikon (Sokkia) RAW file formats are very different. I can give new, useful answers to both questions, though i'm uncertain as to whether they should be classed as duplicates or not -- probably not.
Comment: Similar Q&A: http://gis.stackexchange.com/questions/80107/acceptable-traverse-field-file-syntax-and-field-file-processing-on-copan-11-11-w
Comment: @martinf I'd run across one of your past answers mentioning a conversion tool that handled a variety of formats but couldn't find it or remember the name. I also knew that Total Station formats were varied and different, just like digital camera raw files. I can see two routes - a single question titled 'Total Station file' in general (personally I favor this), or editing the two separate questions (in title) to specify maker and not just file extension (which implies but doesn't guarantee format). You should definitely give a new answer to the old question if they aren't merged.
Answer: As you have discovered, starting with ArcGIS 10.0, Survey Analyst has been deprecated. The functions were split - Cadastral editor was integrated into the two higher license levels, while the Survey Editor functions are no longer supported.  However, another extension called Data Interoperability may allow you to read and import your file, among others. It isn't cheap if this is a one-time thing.
I am not familiar with that particular file format - is it binary or text based? If text based it may be possible to figure out a script or conversion process. If binary, it may require a different third-party software for the conversion. I went to the Sokkia site and their software offers a free trial (as does the ESRI Data Interoperability extension).
Answer: There's a free software package, Copan, that can read several different total station data files, including Sokkia/Nikon .RAW, and possibly do the necessary cogo calculations to derive and save point coordinates in .CSV format. That output can, presumably, then be imported into any GIS or cogo software.
I say "possibly" because it depends on whether the traditional, raw data, angles-and-distances, have been recorded -- what Copan can work with directly -- or the alternative, reduced data, coordinates, have been recorded. (That's why i ask you to provide a file sample.)
In the latter case, Copan will present them for you still but need to do some manual editing to get them into a perfect format. As a former developer of Copan, I know it was on the ToDo list to accept and use coordinate input from total station files, but we never got around to it.


When was the earliest appearance of Empirical Cumulative Distribution Plots?

Question: I would be surprised if we actually had a date here. I am curious who, if anyone, created the ecdf plot. When did the ecdf make its first appearance? If we do not know when the first ecdf plot was made do we at least have a general time period of when the started to show up?
Comment: Geologists have long used versions of the ECDF, usually for the logarithms of particle sizes.  See for instance the (complementary) ECDF plot in figure 2 of Abrams, Duff Andrew. 1919. Design of Concrete Mixtures. Structural Materials Research Laboratory, Lewis Institute.  (Google Scholar links to a pdf.)  I am having trouble finding anything earlier than that.
Comment: Although obviously not expressed in terms of probability distributions, Fourier's plot in *Notions generales, sur la population* (1821) may qualify: http://euclid.psych.yorku.ca/SCS/Gallery/milestone/sec5.html#1821Fourier
Comment: @Arne Good find!  And the date is closer to what one would expect for the first use of an ECDF (which surely ought to come after 1657 after Huyghens' book or Graunt's book in 1662 but most likely would have been in the late 18th or early 19th centuries when Playfair and others began to demonstrate the power of statistical graphics).
Answer: It was in 1933.
According to M.A. Stephens, Kolmogorov first formalized the notion of empirical distribution function.
Additionally, according to D.A. Darling, it was originally used to define the Kolmogorov-Smirnov statistic, so it was in fact Empirical Cumulative Distribution Function.
Stephens, M.A. (1992). Introduction to Kolmogorov (1933) On the Empirical Determination of a Distribution. In: Kotz, S., Johnson, N.L. (eds) Breakthroughs in Statistics. Springer Series in Statistics. Springer, New York, NY. https://doi.org/10.1007/978-1-4612-4380-9_9
Darling, D. A. The Kolmogorov-Smirnov, Cramer-von Mises Tests. The Annals of Mathematical Statistics, vol. 28, no. 4, 1957, pp. 823–38. JSTOR, http://www.jstor.org/stable/2237048. Accessed 15 Nov. 2022.
Comment: (+1) I've edited this to include full citation information for the articles that you reference. This will make it easy to find these articles, even if the link goes dead. It's easy to include full citation information because most academic databases have a button that will give you the citation data with 1 click.
Comment: So when was it?


Do I need a special seed or type of tree for growing a bonsai tree?

Question: I want to grow a bonsai tree. Do I need a special type of seed or tree for me to be able to grow it as a bonsai tree?
Answer: You do not need a special type of seed or tree for it to be able to be grown as a bonsai. Bonsai trees are just normal trees that are kept from growing big.
There are certain types of trees that grow better as bonsai trees and are easier to keep small (and in a small pot) than others. These are however, still normal trees and not some special mini species of the tree.
When looking to buy seeds or saplings you can simply buy the type of tree you plan to grow. You do not need to buy a special 'bonsai' or 'mini' species of the tree.
Comment: Excellent answer TheWhiteAfrican...I would add that I would choose a species with the smallest leaves possible.  That gives the illusion that the leaves belong to the tiny trunk...as in models.  And I will add, one should definitely take a hands on class at least once, from a master.  To do Bonsai off the internet is setting oneself up for heartbreak.  As a humongous master gardener, I would not try this without lessons from the best master possible even if it entailed learning their language, grins!!
Comment: I am a bonsai hobbyist. Lessons from a master might be nice but iare not necessary. There are abundant resources on the web such as the artcles at evergreengardenworks.com [link](http://evergreengardenworks.com/articles.htm) and forums like BonsaiNut.com [link](http://bonsainut.com) to name two. It is not a 'pass time' for those who fear failure, It is a fun thing to do for those who like to dive in and learn by doing. Masters will only speed learning the artistry of bonsai, if you can afford it.
Comment: Grins, I agree with your dive in and either learn by doing or drown approach!!  The masters I've worked with had no translater and learning was all tactile and visual.  Broke my heart to lose a 15 year old baby I tried...but waiting for retirement when one has a better attention span might help me to take this up again.  I love the 'groves'.


What is the meaning of "longer electrical length = more wavelengths"?

Question: Reading a Keysight-note, not sure what is the following selected line means?
I read and understood the meaning of electrical length, how it is related to bit in flight and wavelength is not clear.
Comment: You may have in your hands a piece of marketing material. It's no more a technical writing. It can have been a technical writing originally, but a professional advertisement text poet has modified it to something else. The poet surely knows numerous technical terms but cannot write cold facts in an exact way like an engineer would write to another engineers. The paper probably is targeted to persons who want to read something about the subject before giving the money to engineers to buy the product they want. The idea is to create illusion "I understand this and it's an useful product".
Answer: While the document talks about more wavelengths, usually the threshold where large impedance mismatches start to matter is regarded as 1/10th of a wavelength for digital systems. Below that the practical effects of impedance mismatches are small, and at 1/4th wavelength they are already quite large. For analog and RF electronics the threshold can be even lower.
Let's first take a look at what happens in a long cable with a severe impedance mismatch at the far end:

The transmitted wave reflects at the impedance mismatch, and the reflected wave adds up with the transmitted wave. Depending on exact length of the cable, the location and the size of the mismatch, the waves add up to either a slightly distorted signal or to a full standing wave behavior I've drawn here.
With careful design and control of the cable length, the reflection can be taken advantage of, such as in quarter wave impedance transformer. However, normally we want systems to work the same way independent of the exact length of the cable. To achieve this, proper termination must be used to avoid distortion due to reflections.
But, what happens in a short cable?

Because of the short length, the phase of the reflected wave is almost the same as the transmitted wave. Thus overall distortion remains low, and there is little effect from the impedance mismatch.
The document also mentions intersymbol interference. This applies to the data transmitted, and relates to how many following bits can the reflection from a single bit disturb. However, I would assume that in most protocols it makes little difference whether the noise is from the previous bit, or a bit that was 5 bits ago.
Comment: +1 Because I never knew why 1/4 wave was significant but that last picture make it a bit more obvious why: reflected symmetry of the half-wave.
Comment: Just a remark on your last statement: Whether interference arises from the previous bit or from a bit N unit intervals (UI) before makes quite a difference in designing equalization circuitry, which will become more complex, occupy more area and consume more power in the latter case.
Comment: @DavideM Ah, that is indeed true for highly sophisticated systems that have equalization.
Answer: You can stuff more identical sticks end-to-end into a pipe if the pipe is longer. Then if you whack one end of the pipe it disturbs more sticks since there are more of them in the pipe.
Answer: This might be referring to mm or cm bit rate wavelengths where path lengths can exceed 1 wavelength. (Many) The reflections will affect more bits than 1. e.g.
Optical or Gbps rates.  So impedance matching is critical.
This is referring to the symbol wavelength rather than the carrier.
Answer: As the length of the line increases, more waves are moving along it.
Think of a stretch of road that has, on average, 10 vehicles/km. A 10 km sectikon would have 100 vehicles in transit.
Also, consider delay. If the average speed is 60 km/hr, it takes 1 minute for a vehicle to enter the 1 km stretch and travel the length, so each transit is delayed 1 minute, and there are 10 items in transit. On a 10 km stretch, each is delayed 10 minutes, and there are 100 items in transit at any time.
3*108m/second: not just a good idea, it's the LAW!*
Answer: Remember that the wavelength is a length, measured in meters.
For a wave with a period of \$ T \$ and a velocity \$ v \$, the signal travels \$ \lambda = v.t \$ in one period.
Thus if you increase the length of the medium (the 'electrical length'), you'll get more repetitions of the electrical signal, i.e. 'more wavelength'.


Best practice for storing HTML coming from text fields to a database?

Question: I have an application that allows users to edit certain parts of text and then email that out. My question is what is the best way to store this in a Microsoft SQL Server database. Right now I have two tables, one holding the HTML data and one holding the plain text data. When the user saves the info, it replaces newlines with br's and puts it in the HTML-conntaining table and then puts the regular text in the other table. This way the text box has the newlines when they go to edit, but the table that contains the HTML data, has the BR's. This seems like a silly way to do things. What would be the best practice? Thanks.
Comment: It's not just SQL injection, you need to also sanitize against Cross-site Scripting (XSS) and many other forms of external attacks.
Comment: Just make sure you sanitize the input to avoid a SQL injection vulnerability.
Comment: Let's say @iKnowKungFoo hits the nail on the head. Storing unsanitized input is like opening Pandora's box.
Answer: It's not silly at all.
Consider the following possibilities:

Store just HTML. That 's silly! Once stored this way, editing it would be painful: you either should decode it, or simply forbid any edition or force users to write HTML.
Store just text. It may work. Until, maybe, you find that converting text to HTML is the bottleneck¹ which slows your application down. For small scale apps, this approach is still ok and probably the easiest one.
Store text and HTML. That's what you've chosen, and it has the benefits of both previous approaches: editing content is simple, and at the same time you don't slow the application down by doing the conversion every time the page is generated.

If there is a thing which is annoying, it's the fact that you are using two tables. Why not keeping this data in a single table, with one column for original text, and another column for HTML?

¹ Remember one rule: don't guess what is slowing the application down: use a profiler. Discussing which approach is faster is good for an informal talk with your friends, but not a good approach to develop a scalable application without doing unnecessary work. My example of saving HTML vs. generating it on the fly, for example, is only good in theory. In practice, (1) you'll cache the results anyway, and (2) maybe, who knows, loading the data from the database may be much slower than generating HTML.
Answer: If it were me, I would just replace the newlines with br's as the text is being used. So, store the plain text (newlines), and then when you have to use it in an email, replace the newlines with br's on the fly.
Answer: You might consider an implementation of BBCode. This will allow you to store plain text, which can be converted to HTML. No actual HTML tags would be allowed.
From Wikipedia:
[b]bolded text[/b]
would become
bolded text
and so on.
Comment: Please, please, please! BBCode sucks for people without technical background, because... oh, I won't even explain why. Ask any interaction designer, if you're interested. And for IT people, there is Markdown, which is highly superior to BBCode.
Comment: What would be the benefit of storing BBCode ?


How to redirect to a specific page on successful sign up using rails devise gem?

Question: How to redirect to a specific page on successful sign up using rails devise gem?
Answer: This page is for you: http://github.com/plataformatec/devise/wiki/How-To:-Redirect-to-a-specific-page-on-successful-sign-in
Comment: Yannis, you misunderstood my question. It was about sign UP not sign IN.
Comment: where you able to make it work ? because somehow it never seems to go through my overridden controller... Do I need to update my routes ? If I do so then I need to have another of views ?
Answer: I hope its not too late, you need to override the after_sign_up_path_for of the registration controller, create a registrations_controller.rb in your app/controller, and override said action.
registrations_controller.rb
<code>class RegistrationsController < Devise::RegistrationsController

  def after_sign_up_path_for(resource)
    ...path of choice...
  end

end
</code>
haven't tested this code so might not work with just copy and paste.
If you look here it will give you the actions for any other redirects you made need.
https://github.com/plataformatec/devise/blob/master/app/controllers/devise/registrations_controller.rb
Answer: The wiki page recently moved and the info is here:
https://github.com/plataformatec/devise/wiki/How-To:-Redirect-to-a-specific-page-on-successful-sign-in-and-sign-out


How can I set up Trac to run on a webserver?

Question: I'm setting up Trac for a project on a Windows Server 2003 which already has Apache2.2 and Virtual SVN already installed and in use. I managed to install Trac and run it on its in built stand alone server but I can't seem to get it to run on the webserver. I have tried various tutorials and guides all in vain. I have installed various additions into Apache2.2 but still Trac cannot be accesed via http.
Anyone with a step by step approach that I can use to configure Apache2.2 so that it can work with Trac and I'm able to acccess it via a url?
Comment: Can you give any more details about the problem other than "Trac cannot be accessed via http"?  When you try to access Trac, do you get a standard 404 page or an error from Trac?  Is there anything in the webserver's log or Trac's log to indicate that it saw your request?  Can you share a link to the specific installation instructions that you are following and indicate how far you made it successfully?
Answer: Have you seen this guide?
http://trac.edgewall.org/wiki/TracOnWindowsIisAjp
Answer: I have recently installed the latest trac (12.1) under Windows XP with the use of Apache 2.2, python 2.7 and mod_wsgi.  I used standard installation instructions from the trac's website. I used mod_sapi to authenticate users against local NT domain. I don't remember the particularities now, I only remember that I took me less then a working day to find all the required software, modules, and set it all up.
I'm not in the office right now, so I cannot paste in the config I have.  If you wish, send me an email to max(-at-)kosyakov.net, I'll send you back the configs and modules once I'm back in the office.


How to evaluate $\lim _{x\to \infty }\left(x^3\ln\left(\frac{x}{x-1}\right)-x\sqrt{x^2+x}\right)$?

Question: $$\lim _{x\to \infty }\left(x^3\ln\left(\frac{x}{x-1}\right)-x\sqrt{x^2+x}\right)$$
I tried like that:
$$\lim _{x\to \infty }\left(x^3\left(\frac{1}{x-1}\right)-x^2\sqrt{1+\frac{1}{x}}\right)=\lim _{x\to \infty }\left(\left(\frac{x^3}{x-1}\right)-x^2\right)$$
$$=\lim _{x\to \infty }\left(\frac{x^2}{x-1}\right)=\infty$$
But the result is wrong, actually it has to come $11/24$
Can you please show me how to solve it (without l'Hospital)?
Answer: About what you did: In your attempt, where did the $\ln$ go?

An approach: Here is a solution using Taylor expansions: we will use the fact that, when $u\to 0$,
$$\begin{align}
-\ln(1-u) &= u + \frac{u^2}{2} + \frac{u^3}{3} + o(u^3) \\
\sqrt{1+u} &= 1 + \frac{u}{2} - \frac{u^2}{8} + o(u^2)
\end{align}$$
and the fact that $\frac{1}{x} \xrightarrow[x\to\infty]{} 0$ (this will be "our $u$").
(Intuitively, we go to order $3$ in the first and only order $2$ in the second since, for our application, we will multiply by ${x^3}=u^{-3}$ and $x^2=u^{-2}$, respectively: we want to do an expansion of both terms of the difference, up until we get a constant.)

First term:
$$x^3\ln \frac{x}{x-1} = -x^3 \ln \left(1-\frac{1}{x}\right)
= x^3 \left(\frac{1}{x}+\frac{1}{2x^2}+\frac{1}{3x^3}+o\left(\frac{1}{x^3}\right)\right)
= x^2 + \frac{x}{2} + \frac{1}{3} + o(1)$$
Second term:
$$
x\sqrt{x^2+x} = x^2\sqrt{1+\frac{1}{x}} = x^2\left(1+\frac{1}{2x}-\frac{1}{8x^2}+o\left(\frac{1}{x^3}\right)\right)
= x^2 + \frac{x}{2} - \frac{1}{8} + o(1)$$
Now, the difference of the two:
$$x^3\ln \frac{x}{x-1} - x\sqrt{x^2+x} = \frac{1}{3} + \frac{1}{8} + o(1) = \frac{11}{24} + o(1) \xrightarrow[x\to\infty]{} \frac{11}{24}.
$$
Comment: I know that if the argument of the $ln$ tend to $1$  i can delete the ln and add $-1$, is it right?
Comment: That's not enough. What you describe is basically a Taylor expansion up to order $1$ ($\ln(1+u) = u + o(u)$; you also did $\sqrt{1+u} = 1 + o(1)$), but here you actually need order $3$: the terms you remove/neglect are multiplied by $x^3$, so even something as small as $1/x^2$ cannot be neglected that way: multiplied by $x^3$, it becomes $x$, and you are considering as negligible something that goes to infinity. (And something, actually, that would conveniently cancel with other terms of the square root, that you also threw away as negligible while they really were not)
Comment: I understand, thank you very much :)
Comment: You're welcome!
Comment: Concise and complete! Nicely presented. +1 - Mark


Clear sap like substance on underside of Chinese evergreen leaves

Question: I just recently discovered some clear sticky dots under the leaves of my Chinese Evergreen. The look and feel like some sort of sap. They can be wiped off but are thick and sticky. There isn't any visible insects that I can see. In the image I am providing they appear white but its just the reflection from the flash on my phone, they are clear. Leaves have been turning yellow on this plant for the past few months, however, I only just noticed these so I'm unsure if that is unrelated to this problem.
Answer: You see this quite often on aglaonema and aroids.  I have seen it more often on plants in good light and think it is guttation which is

the exudation of drops of xylem sap on the tips or edges of leaves

Your diagnostic keys would be to rule out other sources of sticky sap such as scale.  Check the underside of the leaves and the base of the stems for small hard brown bumps.  If you can flick them off with a fingernail then it could be scale.
Most likely this is just dried sap as scale is not normally found on aglo's.  No problem, nothing to do.


Can Inferi be made out of any dead body?

Question: In book six, Harry Potter and the Half-blood Prince, the Horcrux is surrounded by a lake filled with Inferi. Did Voldemort have to use people he killed, or did Voldemort simply just go to a graveyard to procure his army of Inferni? As an example, we read in book seven that Dumbledore says that for Grindelweld the Resurrection Stone meant an army of Inferni. Does that mean he was going to have to kill a lot of people to create an army, or could he just go grave robbing?
Comment: Good start. However Connorjohnson, you have two questions here: One- **from where did Voldemort get the dead for his army of inferi**, and two: **why didn't Grindelwald use inferi as an army?**. I would suggest you to make them as two separate questions.
Comment: I was using grindelwald as an example, sorry should have clarified that
Answer:  The Inferi at the lake were homeless Muggles murdered by You-Know-Who
As described here:

The Inferi whom Harry and Dumbledore encounter in the depths of the lake in Harry Potter and the Half-Blood Prince were, when alive, mostly vagrant, homeless Muggles whom Voldemort had murdered for the purpose during his first rise to power, although some were the earthly remains of wizards or witches who 'disappeared' without explanation.

The second part of the sentence above: some were the earthly remains of wizards or witches who 'disappeared' without explanation indicates a much darker side. You-Know-Who actually dug up the remains of dead wizards (or witches) as well to create Inferi.
Seeing what You-Know-Who used for his Inferi army to guard the Horcrux, it is clear that any body can be turned into Inferi (Muggle, wizard, recently deceased or long dead people as well).

 Grindelwald actually had plans of using the Inferi as an army
As mentioned in Book 7, Harry Potter and the Deathly Hallows, Dumbledore tells Harry that Gellert Gridelwald and himself long ago tried to collect the three Hallows. For them,
The Elder Wand meant limitless invincible power.
The Resurrection Stone was the one they both wanted because for Dumbledore, it meant he could finally see his sister and apologize for what happened. And for Grindewald, the stone meant that he could raise an army of Inferi.
However they never really thought of the Invisibility Cloak and they only considered getting it so that they could complete the Hallows.
Comment: I don't think "disappeared without explanation" means that he dug them up... it means they were wizards who got in his way, he killed them and turned them into inferni, and nobody ever found out what happened to those wizards.
Comment: Earthly remains is a term for the bodies left behind when somebody dies, it doesn't mean "dug up from the earth", so that doesn't actually mean that you can use a dug-up body to create an inferni. It might be possible, but that sentence is not proof, sadly.
Comment: I will add the exact quotes from Book 7 when i get time.
Comment: @Theik i was referring to this: *some were the earthly remains of wizards or witches*. The *disappeared without explanation* could mean that Voldemort had them killed.


iOS Gamecenter Programmatic Matchmaking

Question: I'm trying to implement a real-time multiplayer game with a custom UI (no GKMatchMakerViewController). I'm using startBrowsingForNearbyPlayersWithReachableHandler:
^(NSString *playerID, BOOL reachable) to find a local player, and then initiating a match request with the GKMatchmaker singleton (which I have already initiated).
Here's where I'm having trouble. When I send a request, the completion handler fires almost immediately, without an error, and the match it returns has an expected player count of zero. Meanwhile, the other player definitely has not responded to the request.
Relevant code:
- (void) findMatch
{
GKMatchRequest *request = [[GKMatchRequest alloc] init];
request.minPlayers = NUM_PLAYERS_PER_MATCH; //2
request.maxPlayers = NUM_PLAYERS_PER_MATCH; //2
if (nil != self.playersToInvite)
{
    // we always successfully get in this if-statement
    request.playersToInvite = self.playersToInvite;
    request.inviteeResponseHandler = ^(NSString *playerID, GKInviteeResponse
                                       response)
    {
        [self.delegate updateUIForPlayer: playerID accepted: (response ==
                                                              GKInviteeResponseAccepted)];
    };
}
request.inviteMessage = @"Let's Play!";

[self.matchmaker findMatchForRequest:request
    withCompletionHandler:^(GKMatch *match, NSError *error) {
        if (error) {
            // Print the error
            NSLog(@"%@", error.localizedDescription);
        }
        else if (match != nil)
        {
            self.currentMatch = match;
            self.currentMatch.delegate = self;

            // All players are connected
            if (match.expectedPlayerCount == 0)
            {
                // start match
                [self startMatch];
            }
            [self stopLookingForPlayers];
        }
    }];
}

Answer: Figured it out!  I needed to call - (void)matchForInvite:(GKInvite *)invite completionHandler:(void (^)(GKMatch *match, NSError *error))completionHandler in my invitation handler so that both players have the same match data.

iOS Gamecenter Programmatic Matchmaking


can i use the live playground platform, instead of local installation?

Question: I wen through the environment setup detail and  got a problem.
The thing is my laptop is running out of resources. so i decided to utilize the online playground
environment for the tutorial. I just didn't want to make a local installation.
Tell me your words about it.
Thanks all in advance
Comment: At the time of writing playground platform isn't up to date. Progress about this issue is tracked here https://github.com/input-output-hk/plutus-apps/issues/195
Comment: Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
Answer: As the online Plutus Playground is not available at the moment (see
here), and your local computer doesn't have the required resources (around 35GB of disk and 8GB of RAM), I'd recommend to run it in a Linux virtual machine in the cloud (AWS, Azure, Google Cloud, etc.), where you'll be able to pay only for the minutes of running time plus a small amount for the storage if you want it to persist, or you can look for a traditional VPS hosting that you can find for less than $10 a month. Cheers!


Is something on the IO logic board burnt or..?

Question: yesterday, i plugged my macbook pro to charge, and my magsafe charger got a little burn where it connects to the magsafe charger (wall->magsafe). Now my macbook pro won't charge, no light, no nothing, but it still works perfectly. I tested it with a multimeter and indeed, no voltage and no current comming out the magsafe charger, burnt. Maybe that's from power fluctuations, don't know for sure. The magsafe port has no marks of burning or something. I tried to charge it with 2 different magsafe chargers, still nothing. Could something on the IO logic board be burnt or maybe some safety cautions kicked in?
Answer: Reset your System Management Controller, based on Apple's instructions, to see if that kickstarts your charging subsystem.


RSA with 3e≡1 (mod p−1) and 5e≡1 (mod q−1)

Question: Consider RSA with $p$ and $q$ large distinct secret safe primes in interval $\bigl(2^{(n-1)/2},\,2^{n/2}\bigr)$, and private key $(N,e,d,p,q,d_p,d_q,q_\text{inv})$ computed as
$$\begin{align}
N&=p\;\!q\\
d_p&=3\\
d_q&=5\\
u&=p-1\\
v&=(q-1)/2\\
d&=u\;\!\left((d_q-d_p)\;\!(u^{-1}\bmod v)\bmod v\right)+d_p\\
e&=d^{-1}\bmod(u\;\!v)\\
q_\text{inv}&=q^{-1}\bmod p
\end{align}$$
For usual RSA key size (e.g. $n=2048$) and classical computers, does knowledge of the public key $(N,e)$ allow to factor $N$, or otherwise break the RSA assumption that given $x^e\bmod N$, finding $x$ is hard for integer $x$ drawn uniformly at random in the interval $[0,N)$ ?

If not, this variant of RSA is attractive because the low $d_p$ and $d_q$ allows to perform the RSA private-key operation using the CRT-based method with only 7 multiplications and 6 modular reductions with ⌈n/2⌉-bit parameters. This would have practical applications for parties with low computing power (e.g. an RFID chip): combined with standard RSA for the more powerful party's public key, that would allow mutual public-key authentication with record-low computing effort by the less powerful party.
The keys are conforming to PKCS#1 and compatible with many existing implementations. The public keys are only remarkable for their high $e$, thus public-key certificates are readily obtainable from the many vendors that allow $e$ in RSA public key certification requests to be up to n-2.
When using the standard RSAES-OAEP for encryption and RSASSA-PSS for signature, it appears that the basic fault injection attack in one of the two exponentiations modulo $p$ or $q$ is not to fear.

If this is unsafe [update: it is!], can we save most of the idea, e.g. with $e=d^{-1}\bmod(u\;\!v)+u\;\!v$, or (at the expense of PKCS#1 conformance) to  $e=d^{-1}\bmod(u\;\!v)+n\;\!u\;\!v$, or/and by making $d_p$ and $d_q$ secret but still small (and distinct)?
Credit: that later variant was considered by Michael J. Wiener in Cryptanalysis of Short RSA Secret Exponent (published in IEEE Transactions in Information Theory, Vol. 36, N° 3, May 1990), with security stated as an open problem.

I hereby put in the public domain whatever novelty there is in the present post, and grant every legal entity a free, worldwide, perpetual, nonexclusive license to use such novelty.
Answer: This is a very bad idea.
Given a ciphertext-plaintext pair $c,m$ I compute $\mathrm{GCD}(c^3-m, N)=p$.
Keeping small but secret $d_p$ and $d_q$, they'd still need to be too large to exhaust over. For 128-bits of security then, you'd probably want $d_p$ and $d_q$ of 128-bits. This does offer some savings over vanilla CRT, but perhaps not enough.
Comment: My earlier comment about smooth $d_p$ and $d_q$ does not apply. I'm also not sure if Wiener's attack can be leveraged. It relies on a continued fraction approximation to $e/N$ with denominator divisible by $d$. In this case we seem to need a continued fraction for $e/p$ with denominator divisible by $d_p$, which I shouldn't be able to compute.
Comment: Beside, we can compute the necessary $(c,m)$ pair from the public key as $m=2$, $c=2^e\bmod N$. Adding multiples of $u\;\!v$ to $e$ is of essentially no help. I was not trusting that it could be safe for public $d_p$, $d_q$, but could not spot that attack immediately. It would still make a nice CTF. And Wiener's open problem of how big secret distinct $d_p$, $d_q$ need to be remains open. It seems to allow a factor of 8 saving compared to standard 2048-bit RSA, making it sort of competitive with standard ECC.


How to apply css style in GTK# with mono development

Question: I am new to mono development with GTK# is that possible to apply css styles to an GTK button in mono development if so can you please explain how to do that.
Answer: Yes and No, The GTK# you get installed if you have a stable/release mono build is written on top of GTK2 which does not do the whole CSS thing. You'll need to wait for GTK# to move to GTK3, that said, the trunk of the git repository of gtk-sharp. Judging by this commit message it now uses GTK3.


Comparing ESRI Demographic Data from different years

Question: I have in my possession ESRI Demographic update data for multiple years: 2013/2018, 2014/2019, 2015/2020, 2016/2021, 2017/2022.  I am currently trying to see if it is possible to compare each of these data sets against each other to ascertain potential customers for highspeed internet service in my county.  For example, a time series analysis looking at population change using the total population estimates for each year.  I have tried looking up this information on ESRI's website but I have not found anything that could help me answer my question, so I am hoping someone on the stack exchange with knowledge of ESRI Demographic Data could provide with one.  If it is possible to do this, I am also considering using other variables too such as median household income, educational attainment, disposable income, age and other socioeconomic measures for marketing purposes.
Comment: "I have tried looking up this information on ESRI's website but I have not found anything that could help me answer my question..." Is the question about finding data, or how to do the analysis?  The answer to the first question is that this data was not created by ESRI, the data comes from the U.S. Census Bureau (which ESRI then repackages with their products because demographic data is a common dataset for use in GIS).  So if you are looking for more/ complete data, the Census Bureau website is where you want to look.
Comment: I am inquiring more about the possibility of using the population estimates to perform trend analysis.  I am interested in using the population estimates for each year to see how they fluctuate over time.  For example, lets say that I want examine population change from 2013 to 2017.  I want to use the population totals for each year, but not the projected estimates.  Can I use those initial totals for analysis and are they comparable to each other.
Comment: The Census Bureau only conducts a complete census every 10 years (2010, 2020, etc.)  I'm fairly certain anything between those years are based on estimates, however that doesn't necessarily preclude you from being able to perform trend analysis on the data.  Here is a link to the documentation of how they produce these estimates: https://www.census.gov/programs-surveys/popest/technical-documentation/methodology.html
Answer: If you are only looking at a single county, I assume you're probably looking at Block Group or Tract level data?  Since the number of records in your dataset should be relatively small, and you have all of the data available, I would just export your selected records from the most recent dataset to a local geodatabase.
If you are just looking at population, it would be easy to just add new columns for each year's population (pop2013, pop2014, etc) and just join your "previous years" tables to your master, calculate the new field from the joined field, and repeat until you have all of your previous year data in your master.
If you want to add in more fields, look at using the "Add Join" or "Join Field" tool and scripting the process via ArcPy/Python, where you can manage the naming conventions for adding fields and methods of joining/calculating the attributes from one source to the master.


Why does soap solution forms bubble but tap water does not?

Question: The surface tension of water reduces on addition of soap to it. Then why does normal water not form bubbles but soap does even with less surface tension?
Answer: To form bubbles, you need less surface tension, not more. Because the surface tension makes bubbles less stable. This is why we add soap.
As a simpler analogy, consider just making a puddle of liquid on a flat surface. If the surface tension is low, you'll have a nice flat puddle. But if the surface tension is high (e.g. with mercury - don't try at home), the puddle will break into smaller puddles or even individual drops of the liquid.
Pretty much the same thing happens to bubbles - the surface tension doesn't hold a bubble together, it tears it apart.


How can I separate pages in this tape-bound booklet?

Question:
My grandparents fancy posting to walls some pictures in this Travel Alberta catalogue, rather than paying for pictures (to be printed). But they can't cut out pages as the pictures are printed without borders on some pages; cutting out pages would cut out the picture too.
Am I correct that this is denominated tape binding?
Comment: Why can't they cut the pages? I didn't understand your logic on this part. If you mean some of the pictures spread across two pages, and you don't want to lose the part of the picture in the middle, you might find that forcibly opening the book at that point, breaking the spine will allow you to cut the page out. Please expand your question showing some examples of pictures they might want to extract from the book?
Comment: @CaiusJard Each page extends all the way to the spine. They can't cut along the the spine, only a few centimeters away from it.
Answer: I think it's more likely to be perfect binding than tape binding, but the two techniques are similar. It's often a heat-softening glue that is used to bind the pages, so you may find that heating the spine to a reasonably high temperature (with a hair dryer or similar) will soften the glue and allow pages to be pulled out. You may find, as per my comment, that forcing the book open and flat against the table at the page you want will break the spine/fold the glue and allow full view of the page to be extracted. Pictures that span two pages and run across the spine are unlikely to be printed right the way up to the page edge, so some careful use of an craft knife (a knife with a thin razor edge blade that is pre-scored into sections and can be progressively snapped to create a new sharp point) and a metal ruler will extract the pictures you want
Perhaps also, consider that the internet will be stuffed full of pictures that are vistas and scenes from Alberta, both professional and amateur, with and without royalty or licensing. Named places and known tourist spots/events should be easy to search for and ideally would be detailed or referenced in this catalog, so finding a digital high quality version of favored pictures, that you can have professionally printed up onto canvas etc as a gift, might make for a better overall result.
Comment: Thanks. Your last para.: They're trying to avoid paying for pictures (to be printed).
Comment: If you bought(or maybe you know someone with a big printer) them one (as a gift) then they wouldn't be paying for it, and it could work well as a birthday or anniversary item- I know I always struggle for gifts ideas for my grand parents because they seem to already have everything they want and here is only so many times I can hug the same bottle of whisky before it starts to look like I put no thought into it!
Comment: @Greek-Area51Proposal Before you download and print (copy) an image found on the Internet, you might want to investigate the existing Copyright laws in effect where you are. This violates Canadian copyright laws for example. Just because you can, does not mean you should.
Comment: @Stan hence the *"with and without royalty or licensing"* wording - I make the basic assumption that people are generally good, and will seek to properly license a licensable image for the use to which they intend to put it..
Comment: Royalty and or licensing is completely unrelated to Copyright law. Big difference. Your comment suggests a widely held misunderstanding of this. In addition, since you mention Alberta, Canadian copyright law exists automatically with the creator of the content unless specifically and legally 'assigned' to another entity. Canadian copyright law has been recently made much more stringent than a few years ago. Students here may not even photocopy a page from a textbook. Do check with a legal professional regarding your assumptions regarding this. Please edit your answer to reflect this reality.
Answer: As you are going to cut-up the pamphlet and remove pages, there's no need to preserve the pamphlet.
The best way to remove pages from a glued binding is to

'Break' open the binding at the page you want to remove and flatten the book on a table top. Don't heat the glue as this will liquify the glue which will create a mess. Better to cool the pamphlet so the glue is brittle.
Turn the book facing up.
Inspect the "reader's spread" (That's what an illustration that crosses two adjoining pages of a book is called.) If you are lucky there will be a thin white inside margin space between rough edge of the pages and the photograph.

Decision time: Before you do remove the page, If the edges of the photograph appear to not match if you trim off the margin, you may wish to stop at this point. You can still preserve the pamphlet by closing the booklet and heating the binding glue to re-seal the pamphlet.

If there is a white margin, pull the desired pages from the booklet. Doing this carefully, will let you pull the page as if it was a sheet in a "memo-pad" without tearing it. The inside edge of the removed page will be ragged and may have a bit of glue that you can remove with your fingers.
carefully trim the edge from one page of the pamphlet. You will use this to overlay on the page that still has an edge margin. Trim just enough from the bottom page to remove rough edge that might remain from where you pulled the page free from the broken spine
Use glue or double-sided tape to attach the upper page onto the bottom of the assembly making sure to align the edges as best you can.
If done carefully, You will be able to place the "double-trucked" (another term for abutted pages that make up an illustration that crosses the "gutter" of the pamphlet.

Usually, these kinds of pages are printed "bleeding edge" which means printed right to the edge of the page with no margins.

You can either matte the print assembly (in a hole cut slightly smaller than the picture from a decorative paper to frame the print) or just centre the page on an attractive background and frame the picture for your grandparents.

I think that's a very nice thing to do.
Good Luck, and have fun.
Comment: Many thanks! "crafts.graphicdesign.com": Is this link correct?
Comment: @Greek-Area51Proposal  Updated - correction: You might want to ask this question at https://graphicdesign.stackexchange.com where I and others who do this stuff everyday hang out. Other opinions about the best way to do this might also be suggested at https://crafts.stackexchange.com


image not rendering properly (weird orange grain)

Question: so, every time I try to render my image, i just get a bunch of orange noise. i can't even see the image I'm trying to view
Comment: What was your expected render? Can you add a picture of your viewport?
Answer: Go to the outliner. Select your camera. Go to field of view (FOV) and check it says 35mm. Then go to the depth of field, uncheck it to render. If it renders, go back and re-check field of view, type 24mm and check results.
Also, on the N -panel on the viewer uncheck depth of field.
Thank you for your consideration to choose this as the correct answer.
BFCT_Schiller
Comment: i don't understand, i try to go to the depth of field, but I don't see anything to "uncheck".
Answer: You're using Cycles and that's normal for it (lots of calculations) with materials such as glass or when your object is complex/large, of which the progress bar is the proof. If your final render is OK nothing bad happens.


How to install onto a non-bootable pc

Question: I have an old Windows computer that won't boot (missing NTLDR or something??).  I don't even remember what Windows OS was on it.  Anyway, what I want to do is this: forget Windows and install ubuntu on this computer and then possibly sell it as a fully functional machine.  Can I download ubuntu onto a set of cd's or dvd's, using this Vista pc, then take the downloaded media to the broken machine and install ubuntu system from them?  Will the downloaded system on the cd's be bootable?  I have an old Win98 startup diskette that will boot to drive A: and that will let me change to drive D: (the cd drive).  So if the downloaded ubuntu system on cd's or dvd's is bootable, can I proceed to install it from there?
Comment: What do you mean by non-bootable?  If the BIOS doesn't load/past POST/etc. than the answer is probably no.  If you just mean that it doesn't boot into Windows, get yourself some Ubuntu installation media, change the boot order in the BIOS and you are good to go.  Definitely no need for a Win98 startup disk at any point....
Comment: can you be more specific about your computer spec. and there is not such thing like "non-bootable pc" seems like your machine is just old, and missing NTLDR (as you have mentioned)
Answer: "missing NTLDR" is a Windows error message (NTLDR is the small program that boots Windows NT). If your computer makes it to that error message, then it is booting properly and has no issues, it is just the windows install that's broken.
So, the computer is not "non-bootable". Depending on how old is "old", it may be unable to boot the installation media directly, in which case you can just use a floppy loaded with something like SmartBootManager, which is able to boot CDs itself (no matter whether the BIOS supports bootable CD's or not, SBM has its own implementation of El Torito (the bootable CD standard)).
You can use SBM if you have a floppy drive. I'm afraid the Windows 98 floppy won't be of much help here (there is probably some clever way to boot a live CD from MS-DOS, but it won't be as easy as just trying SBM).
Comment: Also,after you download the Ubuntu ISO, make sure that when you burn it to a CD, use a burning software that is capable of making a bootable ISO. In Windows Nero, Roxio, and DeepBurner are examples of capable programs. Windows CD writer is not.
Answer: First thing to do is check if your hardware can handle Ubuntu.  For a list of system requirements Click Here  and read the part that talks about requirements.  But I can tell you from past experience that it will be fine to install Ubuntu.
1) Get Ubuntu Click Here
2) Burn The .ISO file that you downloaded into a CD.
3) Turn on the computer in question on.
3) Place the CD it in CD Drive of the the computer that you want to install Ubuntu on.
4) Go into the BIOS, and change the boot order to boot from CD.
5) Save and exit BIOS.
6) Ubuntu installation will start once the CD boots.
For more detailed or step-by-step instructions Click Here

How to install onto a non-bootable pc


Lost 30 lbs in 6-8 months. But need to bring down fat percentage

Question: I am 5'10''. I weighed 193 lbs last May, now I have reduced to 164 pounds(stalling at the same weight for over 2 months) with 23% of body fat. I need to get rid of those and bring down my weight for 154, which is the cut-off for being fit for my height. I lift weights. I do legs, but I still feel my butt is kinda out of shape, my tummy has a flab(it is kinda flat though), my chest is not exactly ripped(if I don't do chest for 3-4 days, it kinda pushes out in an awkward shape). I need to fix all these(am planning with in Feb). I can do push ups but not pull ups. Since I am stalling with the same weight for too many days, I know I have change something. Right now I do weights about 3-4 days a week, alternating lower body(squats,deadlifts, kettle bell swings), upper body(SMP, pushups, shoulder, bicepts curl(25lbs)). I need to fix my body fat, tighten my butt, flat abs, curl my shoulders more. Am I doing anything wrong, would you change something on what I am dng to achieve wat I want. The trainer at the gym insists that I do the same thing, but I think I need to change something. I know there would be lots of similar threads and sorry for custom posting.
Comment: Are you male or female?
Comment: What are your squat, bench, deadlift and overhead press numbers?  If you are a male, I can assure you that 154 at your height is a lot smaller than the cutoff for being fit.  This is the middle of what the BMI calls normal weight, but 180 at 10% body fat should be acheivable naturally.  Check out http://www.naturalphysiques.com/28/fat-free-mass-index-ffmi
Comment: How are you measuring body fat?  23% @ 5'10"/164lbs Male sounds very high, unless you have quite a small frame.
Answer: Take a look at what you are eating, and get real with yourself about it.  If you have to, track everything until you really know what you are eating.

Protein should be up around 1g / lb lean body weight, preferably from lean meats
You should be eating plenty of fibrous vegetables
You should be getting roughly 1/3 of your calories from of healthy dietary fats (organic butter, coconut oil, olive oil, fat in organic meat, nuts, etc.)
The remainder of your calories should be in the form of high fiber carb sources like brown rice, sweet potatoes, potatoes, etc.
Calm your sweet tooth with whole fruit (not juices)

The types of things you should be avoiding include sugar, trans fats, and foods high in manufactured food substitutes (like hamburger helper).
Exercise is great, but you will do better if you don't count the Calories you expend against what you eat.  For example, if some chart says you've burned 500 Calories from your exercise resist the temptation to eat 500 Calories more of anything.

If your current diet includes trips to fast food restaurants, chances are you are consuming far more Calories than you realize.

At some point, in order to keep progressing in cutting fat you will have to reduce your Calorie intake further.
Also note, how you track body fat may be part of the problem.  One example is the bioimpedance scale which is an approximation built on an approximation which is not only inaccurate it is even worse when used for tracking change over time (by +/- 8%).  You might have lost fat and the bio impedance scale registers no change.  Part of the problem is how the scale takes its measurements and ignores subcutaneous fat.  Tape measures and simple weight measurements give a better overall picture of progress.
It doesn't hurt to have some low intensity steady state (LISS) cardio work in your routine.  Not only is there benefit with burning a few more calories, it also can help you recover from your exercise a little quicker and sleep better by lowering your resting heart rate.  Sleep is very important in any weight loss or muscle building endeavor.


DSAS Can't Recognize Baseline and Shorelines

Question: I have two shorelines and baseline which were created in accordance with the necessary rules such as attributes, coordinate system etc. All data in a personal geodatabase for DSAS analysis. The problem is that neither the shorelines nor the baseline appear in Set Default Parameters. Where am I making the mistake?
Comment: Maybe the tool is not smart enough to use layers other than what they name in their [manual](https://woodshole.er.usgs.gov/project-pages/DSAS/version4/images/pdf/DSASv4.pdf). Page 20 says "DSAS requires data to be in a projected coordinate system using meter units. "
Comment: I am having the exact same problem. My baseline shows up in the default parameters, but my shorelines do not. I tried both solutions (ticking the extensions box for DSAS and remaking the feature class in the mdb), but neither solved this issue. Has anyone else been able find a solution?
Comment: It doesn't look like it's an issue in your image. Make sure you haven't 'grouped' the data layers before using the DSAS tools. It wouldn't register my shoreline/baseline until I 'ungrouped' my files.
Answer: I had the exact same problem and I tried both solutions (ticking the extensions box for DSAS and remaking the feature class in the mdb), but neither solved this issue.
I was able to find a solution after playing around with the sample data they provide. Their shoreline feature class was made up of "Polyline M" files, whereas mine were only polylines (you can find this under the shape field in the attribute table). I remade my feature class and made sure to click the box next to "Coordinates include M values".
This fixed the problem of disappearing shoreline fc and allowed me to calculate the shorelines change. Hope this helps you!
Answer: I had the same problem, more or less... In my case the baseline was recognizable, but not the shorelines. For me, this was fixed simply by going to "Customize" --> "Extensions" and ticking the box next to the DSAS extension, that has been deactivated, for some reason.
Answer: Make sure to create all features classes (fc) directly in the mdb. The first time I tried, I imported the fc from the GDB to the mdb, and still DSAS didn't recognize them.
Therefore, I created the fc in the mdb and started an edit session. I just selected the features in the previous fc and paste it in the new one. It worked!
Answer: I tried all of the above and it didn't work. Instead I actually typed the baseline layer in and it eventually showed up!