Why do time series questions get such a low response rate?

Question: I know the response rate on this site is lower than most SE sites, but even taking that into account, the response rate to time series and forecasting related posts seems abysmal. Is there are reason for that? Can anything be done to improve on this?
Comment: This is a statistical site, so do you have any data for that? Assuming it's true, and I don't disbelieve it, I have one guess only. Forecasting is difficult at best and many posts here that I see are frankly rather naive. They have the flavour "I have data and wish to forecast future values". So far, so good, but it is frustrating, I imagine, even for experts (I'm not one)  to spell out what just about every forecasting text not based on snake-oil spells out: many methods, no panaceas, know your system, explore your data, etc., etc.
Comment: @Alex, I also had the impression that the answer rate for `[t-s]` questions was lower. I was surprised at how trivial the difference is. I don't have the impression there is a problem w/ `[regression]` questions, & I've never heard anyone complain about it, but the difference is less than one tenth of an answer per question. As for why it differs *at all* (even if only trivially), it again has to do w/ who & how many people there are answering those Qs. Eg, there may be fewer active users answering t-s Qs.
Comment: For some data pertaining to response rates, I searched on the top 8 tags & divided the total # of answers listed by the total # of questions. The resulting rates were: (**1**) `[r]` $.964$; (**2**) `[regression]` $0.973$; (**3**) `[machine-learning]` $0.997$; (**4**) `[time-series]` $0.899$; (**5**) `[probability]` $1.103$; (**6**) `[hypothesis-testing]` $1.048$; (**7**) `[self-study]` $0.967$; (**8**) `[distributions]` $1.029$. (cc @NickCox)
Comment: I don't follow that tag, so I can't really speak to that, but in general it's a question of how many / which users have expertise on a topic & how much of their own time they can dedicate to helping others on the internet for free.
Comment: Another statistic to look at would be a proportion of unanswered questions from all questions. It's 5724/15172 = 0.37 for [regression] and 3431/7792 = 0.44 for [time-series]. @gung
Comment: Related: [Why is our answer rate so low?](https://stats.meta.stackexchange.com/q/1538/)
Comment: The pattern I identify is common across many topics. Again, to forestall a fair comment, I have no data. I am just trading in impressions.
Comment: @gung so my intuition that time series has a response rate lower than the rest was correct. As to your initial comment about users dedicating time - given how involved and detailed many of the answers on this site are, why would time series be the one topic were experts can't be bothered to put too much time into answers?
Answer: It looks like I'm one of the more active users in the forecasting and time-series tags. Here is my subjective take.
I very much agree with Nick Cox' comment. Many, if not most of the questions especially in the forecasting tag seem to fall into one of two categories:

The OP has quite obviously not read anything on forecasting, such as the excellent free online forecasting textbook Forecasting: Principles and Practice by Hyndman & Athanasopoulos (2nd ed.), which I keep recommending over and over. And over.
With steadily decreasing enthusiasm, though. By now, anyone who looks through CV before posting, or who performs a simple search (the 1st edition of FPP is the very first hit if you search for "forecasting textbook" at duckduckgo.com - your results on Google will depend on your personal search bubble) should find it.
If people obviously haven't found FPP, or have found it or a similar forecasting textbook, but have decided to rather post a question than look through the textbook before posting, this seems to be a clear case for downvoting ("shows no research effort"), but considering that these questions often seem to come from new users, slapping them with a downvote on their first question seems to be overly harsh. So I'll often comment that they look at FPP2, instead of writing a full answer.
The question is a slight variation on one of the many, many questions we already have on forecasting. It's a hassle to find the closest match, and even if I do find one, it's often not obvious to the OP why this duplicate contains the answer to their question - if they knew enough about forecasting to understand the connection between the duplicate and their question, they wouldn't be asking in the first place.
So voting to close as a duplicate will often require some commentary. I'd love to have the time to provide this commentary; unfortunately, my hungry children rely on me to put food on the table, and my employer does not pay me for spending time on CV. So I often write a comment to point to a related question and leave it at that.
Case in point: I recently looked at a question where the OP essentially asked why the forecast was a flat line. I thought that there should have been tons of answers to this exact question, but I only found similar questions, no duplicates or canonical answers, so this time, I went and wrote a short answer, essentially to have a duplicate to refer to later on, since this kind of question will appear again.

It doesn't help that forecasting seems to be a topic with a high share of drive-by posters. I have a mental image of someone with little to no statistical knowledge being saddled with the task of forecasting sales, because they didn't look busy when the boss came around, or because they are known to be "good with figures". So off they go with little understanding and post a question along the lines of (1) and (2) above here. And even if they do get an answer, they don't accept or upvote. No, I'm not only here because rep tickles my already-inflated ego - but writing an answer and not getting any feedback doesn't encourage me to write more answers the next time a 1-rep user asks an un-upvoted not-very-good forecasting question. Sorry.
Conversely, my mental image (I emphasize that I'm just conjecturing here, I don't have data) of someone who posts in the mixed-model or chi-squared tags is someone who has at least looked into a statistics textbook or taken a stats course at some point in time, maybe while studying psychology or medicine. Answering here is typically more gratifying.
A related problem is that there is no clear point where a forecasting problem is "answered". Here, I am thinking of the time before the question is asked at CV. Someone may have read about Exponential Smoothing or ARIMA and applied it to their data, but they may feel that forecasts could be better. And this is often the point where they come and post questions on more elaborate methods here. In forecasting, it's not clear when the search ends. (Compare many other tags here.) This is exacerbated by my point above, of forecasters typically not having a lot of statistical training, so disabusing them of the notion that adding more data or using more complex models will not automatically improve forecast accuracy is an uphill battle.
So, to answer your question of whether anything can be done to improve the answer rate on forecasting and time-series questions: unless questions improve in quality (unlikely), it seems like we may need to be less stringent in closing as duplicates, or we might want to tolerate (and write) more short answers. Of course, it would help if we got more people to answer in these tags, too, so I'm looking forward to upvoting many answers from you in the future ;-)
Comment: Having been the second or third most active guy in the [forecasting] tag in 2016 and 2017, I largely agree. The issue with full or near duplicates has become quite tiresome for me; I do not want to write yet another nearly identical answer to a nearly identical question but I do not have the time and energy to find the duplicate either. It would be nice if we had some more canonical threads to refer to (5 or 10 could summarize a lot), but creating these threads again requires energy. I agree about the "no research effort" questions, too. As a consequence, I have reduced my activity in the tag.
Answer: Maybe the following analogy/viewpoint may help. Comparing with StackOverflow you could see questions as 'bug-reports'.
On SO those bugs are specific and concrete. If some bug or other type of problem exists in a program or computer language then many other people have encountered the problem before and when they come across somebody else with the same problem then they can easily recognize the problem and also easily explain how to hack/solve it, and this effort (which is not so much) is very rewarding because many people will encounter the same problem and be helped.

In statistics problems (bugs) are often much more vague and, unlike
mathematics, definitions are not always precise (e.g imagine a
question of the type: what is the best optimization/estimate/technique/etc.).
There are many very specific questions a computer bug can often be pinpointed to a clear cause. Problems in statistics are much more varied and solution strategies change depending the circumstances. This creates a lot of load, many different questions, that are basically the same. It is difficult to order the questions, and often questions (with little generality) are not so inspiring to answer.
There are many badly described/defined problems (with little information or by people that lack the ability to express themselves properly).
There are many problems that are very broad. Many questions are not like simple bugs. There are often questions that ask for a full consultation on an entire broad case/problem.

I imagine that this is might be more expressed in questions on 'time series'.
Or at least, from my perspective, I find time series often cumbersome, vague, and also very specific. To solve a problem you can pick out one of many solutions and variations thereof and it seems more like an art than science. Still I like these kind of problems, but often the solution strategy requires a more in-depth look into the problem case, and it is not often inviting to answer them via this medium.
(If I have time I will search for a statistic on the length of the questions. My hypothesis is that 'time-series' questions have much larger length in terms of words/letters, because they are so specific. also anything related to 'forecasting' may do worse. E.g. people dump a lot of data and images, which still doe not provide a good/sufficient picture of the problem, and ask for a solution)
Comment: I will see how to improve it. I have already edited a lot and am working on this answer. My basic idea is that I find time series often cumbersome, vague, and also very specific. Solving a problem you can pick out one of many solutions and variations theroef and it seems more like an art than science.
Comment: The focus of the question is why are time series different (and confirming that they are different is crucial; @gung's evidence suggests that the differences are not enormous and thus should not be over-interpreted). Thus it's a question of how many act in the presence of time series questions rather than how you feel personally. At the same time, I too make guesses as a projection of my impressions!
Comment: Good points, but last sentence needs elaborating. Everything until the last sentence could be a better fit for https://stats.meta.stackexchange.com/questions/1538/why-is-our-answer-rate-so-low.
Comment: @NickCox this seems more like a problem that originates in the question being very open. Therefore, subjective input is necessary before some objective answer can be formulated, if such answer is possible at all. If these speculations on effects are over-interpreting the tiny differences then maybe the question should not be asked?  (although I believe the effects may even still be present without the differences, since there are many multiple positive and negative effects and verifying/quantifying the OPs propositions by looking at simple differences does not seem so crucial to me)
Comment: We agree on essentials.


Multiple devices to single power source

Question: I have a power distribution board for my Quadcopter. It is powered by a 3s Lipo and the following are connected:

12 Volt outlet for ESCs: 4 ESCs 12 Amp
5V Outlet: Connected my 5V Gyroscope and Arduino Nano
12 V outlet: Connected a receiver using 3.3 V regulator.

I don't have any additional outlets.
Question is, how do I add more devices by pulling voltage from existing outlets by connecting in parallel, as the Volts will be the same. I understand Amps will get divided.

Is it ok, to add more devices in parallel to let us say my 12V outlet, where I connect couple of more 3.3 V regulators to run 3.3 V devices and couple of 5V regulators to run 5V devices.

Based on the specification of LIPO and power dist module below, is there a way I can determine the max devices I can connect to both 5V and 12V outlets on my power distribution module?
here is the spec of my power distribution module:
General:

Input voltage range (3S-4S LiPo operation): 9 - 18V DC
Regulated 5V and 12V outputs
6 ESC outputs & 1 pair VCC/GND pads

ESC outputs:

Continuous current: 25A*4 or 15A*6
Peak current (10 seconds/minute): 30A*4 or 20A*6

BEC 5V output:

Designed for RC Receivers, Flight controllers, OSD, and Servos.
DC/DC synchronous buck regulator.
Voltage: 5.0 +/- 0.1VDC
Continuous current: 2 Amps (Max.2.5A 10s/minute)
Output Ripple: 40mV (VIn=16V, VOut=5V@2A load)
Short-circuit tolerant (5 seconds/minute)

BEC 12V output:

Designed for Video TX or FPV camera with linear regulator.
The battery should be 4S LiPo (13~18V DC)
Voltage: 12.0 +/- 0.3VDC
Continuous current: 500mA (Max.0.8A 5s/minute)
Short-circuit tolerant (2 seconds/minute)

BEC 12V @ 3S LiPo

Output voltage= 3S LiPo voltage -1V
Answer: I posted the question in another forum and got a reply. I can power many devices from the power distribution module.As long as I do not exceed the current.

Multiple devices to single power source


Anyway to tell what Vyper can and cannot accomplish compared to Solidity?

Question: After studying both Solidity and Vyper, I really like Vyper's strong security and simplicity. However one thing got me somehow worried, is that unlike Solidity, Vyper is not a Turing Complete language. Now from what I learned back in the school days, any single Turing Complete language is mathematically proven to be able to do everything that any other Turing Complete language can do. That means I know that at least in theory, anything that C, C++, Java, JavaScript can accomplish, Solidity can accomplish too. The only limit is the block gas limit (which is kind of a resource limit that all computer programs need to work with anyway), the language itself is not limited, just like Brainfuck is mathematically proven to be able to accomplish anything that C/C++/Java can accomplish despite it being an extremely barebone language.
However, since Vyper is not Turing Complete, that means that there are things that cannot be accomplished with Vyper, for example, a loop of indefinite size for the most obvious case. The indefinite-sized loop may not be something too useful or cannot be worked around with, however, I wonder if there's some way to tell if Vyper can or cannot work for a certain scenario so that when faced with certain project requirements, I will be able to tell whether I can accomplish them with Vyper or not. I'd rather not take the risk to develop with Vyper and only halfway into the project find out that there is something in the language itself that prevent me from fulfilling certain critical project requirements.
For Turing Complete languages, I have the guarantee that I can accomplish anything that any other mainstream language can accomplish, but for non-Turing Complete languages, how do I tell whether there's something in the requirements of a project that are not supported by the design of the language itself?
Answer: No language on Ethereum is Turing complete, because the EVM isn't Turing complete. There is a maximum gas limit, which means no operation can run for unlimited time or use unlimited space.
Vyper just makes that more clear than Solidity does.


Flashing .tar factory image with CWM

Question: In the hopes of getting Android 5.0 onto my Nexus 10, I visited Google's factory image download page for the latest image. I noticed however that the file I downloaded was a tar and not a zip. Will this work just the same using CWM to flash it, or do I need to do something special here?
Comment: Try unzipping the file in order to get the .tar extension factory image.
Answer: Stock factory images are not supposed to be flashed in recovery. Instead, you should follow the instructions on the page you linked to. Open the tar file, it's probably just a compressed file, just like a zip.
But first, let me point you to some custom ROMs that ARE flashable in recovery:
Stock
Rastakat
Cyanogenmod 12 (unofficial)
However, those may all contain extra bugs, as they are made by 3rd party devs.
Now, if you want to install the actual factory images from Google:
First, make sure you have fastboot and adb. If you don't, install the Android SDK.
Extract the files to a folder on your computer, connect your device to a computer and type the commands into a command window (Start -> Command Prompt or type in
cmd

The commands that you need are the one in green text, but for the sake of completeness:
adb reboot bootloader

If you haven't unlocked the bootloader yet:
fastboot oem unlock

The run the flash-all.bat script:
flash-all.bat

It should look something like this:
Comment: After looking around a bit, I've learned simply executing the flash-all script will wipe all of the device's data, including the sdcard. I've read you can avoid this by extracting the tar/tgz and invoking the specific fastboot commands manually, e.g. `fastboot flash bootloader bootloader.img` etc, and skipping the `userdata` one. I'm wondering, if I'd like to keep my existing recovery, can I also just skip the `fastboot flash recovery` step without expecting any snags or issues?
Answer: The boot loader is not the main problem, it is mainly the encoding of the rom you are using. Instead of tampering with the rom you are going to install, just download rom manager or download the Odin on your laptop. from the internet, download execute variable for your device or .tar if flashing from laptop and apply, DO NOT FLASH AS ROM. this will brick your device. I have tried this method and it has worked without no brick 200+ times. I AM NOT RESPONSIBLE FOR ANY DAMAGE CAUSED BY THIS METHOD; YOU ARE IN CONTROL OF YOUR ACTIONS.
Comment: Odin works only with Samsung devices.

Flashing .tar factory image with CWM


Identify fallacy and opposing argument - Insiders are biggest security threat, therefore insiders can't be trusted

Question: I'm having practical difficulty in getting work done due to the fact that one contractor is constantly arguing against work being done to allow users the access they need to do their jobs efficiently.  The argument is a computer security argument that as most security breaches are committed (intentionally or unintentionally) by inside employees, it should be concluded that trust cannot be given to employees.  I'm thinking that this is some form of causation fallacy,  the facts being that the majority of the breaches being counted could only be caused by employees, so the correlation between breaches and employee responsibility is normal.  It shouldn't mean however that employees can't be trusted.  Am I completely wrong? or is there a good way to counter such arguments?   I'd abstract the argument to 'Most of bad thing is caused by X therefore X is bad'  When the truth is that 'Most of bad can only be caused by X'.
Answer: Just to get the discussion going, I offer my response. The situation is that you think your contractor commits a fallacy when she asserts, "[Since] most security breaches are committed (intentionally or unintentionally) by inside employees, it should be concluded that trust cannot be given to employees." You offer some reasons. I  follow your reasoning to determine what the name of the fallacy might be.
Initially you suggest that the argument commits some causal fallacy. Post Hoc, Ergo Propter Hoc ( After This, Therefore Because of This) is the name for a causal fallacy. The fallacy is committed when a person confuses a sequential relationship (or correlation) for a causal relationship. But I do not see her argument makes any  causal claim. So not is Post Hoc, Ergo Propter Hoc.
Your second idea is that security breaches are irrelevant to trustworthiness, as you separate a bad action by a person from the character of the person.  In this case, her  argument can be viewed as committing Non Sequitur (not follow), which occurs when the conclusion is supported by irrelevant premises. So you can argue that one may not  conclude  untrustworthiness from security breaches.
My problem with identifying the argument with Non Sequitur, however, is that  security breaches do seem to be relevant to trustworthiness. The contractor should have meant trust differently from yours. While you interpret trust as a value-laden concept (good or bad), the contractor should have meant trust with reliability, a value-neutral concept. There is no absurdity in saying  that we cannot rely on those who are prone to security breach.
One suggestion is to argue for the fallacy of division.The fallacy of division occurs when one infers mistakenly that since A is a part of B, and since  B has the property X, A must have X. For instance, since the roof is the part of house, and since the house is painted white, one mistakenly infers that the roof must be painted white. The common sense however is that when we say white house, we mean only the exterior walls of the house.
Applying the fallacy, you can argue that the contractor is mistaken to think that, since  the majority security breaches happen by the employees, it will also happen by your employees. You can rebut that your employees do not share the property (breaching security) since they are qualitatively different  (e.g., they met the govt security clearance). But if your employees are representative of the pool of all employees, then the contractor's claim is not fallacious.
Depending on the situation and interpretation, the contractor's argument  might not be committing a fallacy at all. The disagreements between you and you contract  can be just the reflection of  two competing goals in doing business: security and efficiency.
Comment: Thank you, I think you may have led me to the correct answer to the question.  Not a fallacy of division, but  a fallacy of composition.  I'll explain.  1. presented and accepted as fact:  Most security breaches are ultimately committed by employees.  2. True conclusion is that a percentage of employees can't be trusted - this needs quantification.  3. the false conclusion is that if some employees are untrustworthy then all employees are untrustworthy.  How does that sound?  Is there a simple counter arguments that lays bare such a false conclusion?
Comment: Good counter. I thought about the composition fallacy, but I thought the conclusion was about your employees. Maybe I did not catch the subtly in your presentation.
Comment: I think the conclusion was about all (global set) of employees so including all company employees. I did have one other possible fallacy of affirming the consequent. i.e. all A is B. B therefore A. What do you think?


USB Port Amperage

Question: So I have built a Benchtop Power Supply out of an old computer power supply to power and test misc. gadgets I have created. I would like to attach 2 salvaged USB ports from a junked computer to the 5v rail in order to charge devices from my Power Supply as well. The 5v rail is is capable of 25amps on this specific supply. I plan to attach a USB hub to the port which would extend the total ports to 7.
I am questioning the wires from the main port's ability to hold up to current that may be drawn. If I was to attach 7 devices to the USB for charging I would estimate anywhere from 5 to 14 amps that could be drawn.
If it makes any difference, I have spliced the 2 data wires to each other on the main port.
I'm fairly new to tinkering with electronics, and this power supply is my first real project I've decided to try, so any advice is appreciated. I will include pictures of what I'm working with to hopefully provide any information I may have missed.
I will have of course properly mount and protect all the wires once they're connected, but if I am current that this could draw too much current for the wires to handle. Is there any easy solution to solve this issue?
Comment: Possible duplicate of [AWG for connecting a USB](https://electronics.stackexchange.com/questions/361321/awg-for-connecting-a-usb)
Comment: Note that a USB hub of 7 ports is not a suitable way to get charging level currents out of 7 ports. Such USB hub most likely comes with a 5V @ 2.5A power source. A decent hub will have internal current limit switches at 500mA per port. Obviously you cannot draw 500mA from 7 ports at once as it would overrate the power supply. In addition, even if you tried to supply higher current to the hub from your power supply, it will probably smoke the circuit board in the hub that was designed to only distribute 2.5A.
Answer: Current capabilities of conductors are generally defined by the wire gauge. Look up what gauges your wires are, and search the internet for a current/gauge table. You will find out if your cables are able to withstand the current.
Are the 5V cables connected directly to the usb ports? If so, the maximum current is defined by what the port can hold. You should be able to find a datasheet for a generic USB port to find its capacity.
If there is some sort of circuit between the USB port and the cables, then yeah, it depends on what the circuit is designed for.
Good luck on your starting adventure with electronics! Remember to work safe if working with high voltages (unplug cables from wall sockets etc) Only touch anything if you're SURE you're safe.
Comment: Before touching anything that may be live, check it with a multimeter... Found circuits that stay live because previous people "cross-connected" circuits.
Comment: I will be wiring the stock wire from an old windows computer, that was already connected to the USB port, directly to the 5v rail if I determine this is safe. And yes, I always make sure to unplug devices before touching anything. Luckily I also learned about capacitors before taking my first computer power supply apart. I learned how to discharge them, but apparently they can deliver quite a shock if your not careful!

USB Port Amperage


Why facing the head block?

Question: I have recently came across a problem. One of the rocker fingers (the one that touches the valve stems, and have cam rollers) on my diesel engine head has broken. This resulted in the pistons hitting the valves due to the missed timings. The entire issue has caused me an engine re-haul. But, as part of the repair, I have been asked to machine the head-block face. Then new valves and new rocker fingers were installed, and the timing chain and sprockets where also replaced after facing. But, I don't fully understand why the expensive process of head-block facing was done in the first place. If you face the head, the mating face on the cylinder block should also be faced for a perfect match, right? Any idea why it should be done?

Faced Head Block
Comment: Cylinder heads are prone to warping and gasket imprints since it is aluminum, engine blocks are less prone to this and can be inspected to determine if the block needs surfaced also. I always surface aluminum cylinder heads on engine overhauls.
Answer: Facing is more common with higher time engines, or ones which are suspected of having a warped head after overheats.
In your instance, the most likely reason for the recommendation from the shop was to reduce the probability of a disassembly caused by a head which did not seal and resulted in an unsatisfactory mating between the block and cylinder head.
Generally the R&R costs are pretty high for the head, compared to a small skimming of the head.  However, there is a downside, and that is that some heads, especially on some diesels (VW IDI 1.588L come to mind) have very little margin to skim.
My normal machine shop insists on skimming all heads because they have virtually no problems getting good seals with the cylinder head gasket afterwards, and feel that a clean, smooth surface helps the reassembly reliability.
Answer: It would be helpful to know what engine you are rebuilding but if the repair guide suggests machining the cylinder head only then I suspect that your engine has an alloy cylinder head and a cast iron engine block.
The reason to have the mating surfaces machine is to ensure they are perfectly flat and that you get a good seal on every part of the head gasket with no leaking.  I assume that the repair procedure suggests thoroughly cleaning the engine block mating surface and checking it for straightness with a steel rule and feeler gauge or similar.
It's difficult to know what you mean by "expensive process" but the last time I had a cylinder head machined, it cost less than the equivalent of half a tank of fuel.  Indeed the last time I did a full engine rebuild, giving the machinist the engine stripped to component parts generated an invoice equivalent to around two tanks of fuel or a pair of branded tyres.  Considering that during the rebuild you'll have bought, at least, a gasket set, full set of fluids, timing belt / tensioner and presumably a water pump, the potentially expensive bit isn't the engineering works but the risk that you'll end up having to do the job again with yet another new gasket set if you skimp on ensuring the cylinder head is true.
Comment: Ask yourself this @Subin Sebastian, how much will it cost to have the engine taken apart again to skim the head when it won't seal against the block? Diesel engines have higher compression ratios and cylinder pressure, they put more stress on the head gasket. An imperfect seal is more likely to lead to failure.
Comment: "Alloy-head-cast-iron-block" does this mean, the cast iron is stronger, and thus less likely to have deformations, and the alloy head is not?
Comment: Yes, cast iron is heavy but strong, alloy heads are lightweight and very effective at heat transfer but relatively soft so more likely to warp.
Comment: By "expensive", I mean, the head block facing alone costed me about a full-tank of fuel or the price of one branded tyre.

Why facing the head block?


Can a Smart Contract receive and send E-Mails?

Question: As the title states, I would like to know whether one could create a smart contract on Ethereum that is able to send and receive E-Mails.
Comment: Sure, it can send emails on the Ethereum blockchain (i.e., the data will be on the Ethereum blockchain, and you'll need to implement a client app which will make this data accessible for the users of your email-service).
Comment: @goodvibration Thanks for your answer. Either I don't understand it correctly, or I need another solution. Let us move away from sending and get to receiving first. My goal is that a smart contract can receive emails from any external client without the need for some sort of (web3-?)middleware to get the data to the contract. Exemplary use case: With my Outlook client I send an email to email@example.com and the data is sent directly to the contract.
Answer: If you are perceiving emails as data transmitted over classical protocols stmp, pop3,etc
the answer is No it's impossible. As you might know, the smart contract runs in an isolated environment (VM) it has no connection with external networks.
So a smart contract can't connect to an stmp server and send an email to firstname.lastname@example.com
A contract can receive "transactions" which can play the role of emails !!
Comment: I think I now understand- thanks!
Answer: You could however write some code with the logic to upon receiving text from email, it sends the text to the blockchain via an rpc on the relevant api.


How do I power on devices in CCNA Packet Tracer?

Question: As the question says, i need an answer. I cannot find the power button.
Comment: Try and check if the switch and router are of the same name and type. Dissimilar networks might not get turned on.
Answer: When you double click on a device in Packet Tracer, there is a section for the physical parts of the device (I believe the far right tab, but I can't be sure I'm not close to my computer with Packet Tracer). Here you can change and add drives, interfaces by drag and drop. On that same page there is also the power switch.
Answer: Double Click the device which you want to switch on.Go to physical,Click zoom in,See there is a switch to power on and off.
Thank you.
Answer: When you click on the device the power button on there, (physically in the picture) is interactive click on the power button as if you would physically turn on and off the router itself.
Answer: from the module, drag and drop the AC power supply. and wait for the device to boot. Thank You
Answer: Physical folder allows for adding new hardware and restarting the device.

Select device icon (one click)
Select Physical Folder
Scroll to the far right for power button
Toggle power switch off/on to restart device

There is a Power Cycle Devices button at the bottom of main workspace to restart all devices as well.
Answer: If you zoom in, there is a power port (i could not find a power switch on my IP phone). drag the power adapter from the bottom area of the screen, and bring the male end of the power connector to the female port on the phone. You really have to connect the two ends as you would in real life.
Answer: Power Cycle Devices
The Power Cycle Devices button on the Realtime Bar allows you to power-cycle all of the devices in your network. Pressing it turns all devices off and then turns them back on. Pressing this button will also clear all events if you are running a simulation with the network. The Power Cycle Devices button is also available in Simulation Mode. See the "Simulation Mode" help section for more information.
If you reset the network, you will lose the current running configuration on all routers and switches. Before you click the Power Cycle Devices button, be sure to issue the copy running-config startup-config Cisco IOS command sequence on all routers and switches to retain the current network configuration after the reset.
to power cycle a switch,  go down to the realtime bar on the far left and click the circle.  When you hover over it, it says "power cycle"
Answer: I wasn't able to open the physical tab when double clicking it was only opening the CLI and my physical tab was hidden but i found the solution on another thread  :
Try select Option from menu bar, click "Preference", switch to "Hide" tab and uncheck the "Hide physical tab" box. Hope this helps.


creation of life by Allah

Question: Allah Subhanahu Tala Created each and every being,according to the Holy Quaran...Lets asssume there is a creation who will end up in hell... Allah knew this even before creating it..Still Allah goes on to create it...Why??I mean some will say that Allah has given us willpower with which we can change our destiny....I agree ,,But Allah also knew that he/she is going to misuse his /her willpower and will eventually get deviated..So Why is he/she created??
Answer: according to Quran ALLAH created us only for HIS pray and to test us on the
behalf of us that what we do ,which path we choose ,can we stand with the messenger(Hazrat Mohammad (s.a.w)) of ALLAH or opponent.
Blessed is He in whose hand is dominion, and He is over all things competent -
[He] who created death and life to test you [as to] which of you is best in deed - and He is the Exalted in Might, the Forgiving -
Comment: But if Allah had already determined the outcome of our destinies himself then what is he testing? Is he testing himself?
Answer: the logic is quit complicated behind it, let's assume someone who is non believer god knows his destiny for sure either heaven or hell but there are things in life that can interfere with his destiny like for examples that heart that knows arrogance when it come to analyzing the truth he only recognize what he knows and he trash everything else so this guy is blind for sure so he is not going to get guidance, his destiny is known, why because even he can see the truth he will not accept it because of his pride, so there are two people one with a open heart and the other with close heart and here is in the QURAN SURAH AL HAJJ 46

"So have they not traveled through the earth and have hearts by which to reason and ears by which to hear? For indeed, it is not eyes that are blinded, but blinded are the hearts which are within the breasts."

ALKAHF 57

"Now, who can be more unjust than the person before whom his Lord's Revelations are recited to admonish him, and he turns away from them and forgets the evil end to which he has paved the way with his own hands? As regards those people, who have adopted such an attitude, We have put coverings over their hearts which do not let them listen to the Qur'an, and We have produced heaviness in their ears. While in this state, they will never be guided aright howsoever you may invite them to the Guidance."

why he created us there is no answer surah Al Anbiya 23

"He is not questioned about what He does, but they will be questioned."

SURAH AL BAQARAH 30

"when your Lord said to the angels, "Indeed, I will make upon the earth a successive authority." They said, "Will You place upon it one who causes corruption therein and sheds blood, while we declare Your praise and sanctify You?" Allah said, "Indeed, I know that which you do not know."

ALLAH From his generosity he did not want to be alone. We have been given the presence of us who have never existed, and granted us existence, He created us to prepare us for everlasting life. From the goodness of ALLAH that He gave you the grace of existence. He gave you the opportunity to exist, to enjoy life here on earth, to have a chance to live in eternal bliss, if you want, and to do what makes you worthy of bliss, Allah gave us choices either willingly or unwillingly to worship him.
al-Dhaariyaat 56

"I created the jinn and humans for nothing else but that they may serve Me"
Comment: Very poorly written and does not answer the question in the slightest. If you are going to post an answer then please try and formulate proper sentences.
Comment: you can't not think of Allah's judgments we are not in the position to do so, so this is just an abstract answer

creation of life by Allah


E: Unable to locate package barrier

Question: I am trying to install barrier on my raspberry pi so to enable sharing my mouse and keyboard over LAN.
However when I run the command:
<code>$ sudo apt install barrier -y
Reading package lists... Done
Building dependency tree
Reading state information... Done
</code>
I checked the apt-cache to see if I could it barrier
<code>$ apt-cache search barrier
at-spi - Assistive Technology Service Provider Interface
between - game about consciousness and isolation
execnet-doc - rapid multi-Python deployment (docs)
htcheck-php - Simple php interface to database generated by ht://Check
komi - Single player arcade game with Komi the Space Frog!
libatomic-ops-dev - A library for atomic operations (development files)
libconcurrent-java - utility classes for concurrent java programming
libcurator-recipes-java - Apache Curator Recipes
libpwiz-dev - library to perform proteomics data analyses (devel files)
libpwiz-doc - set of programs to perform proteomics data analyses (doc)
libpwiz-tools - ProteoWizard command line tools
libpwiz3 - library to perform proteomics data analyses (runtime)
libzthread-2.3-2 - Object-oriented synchronization library for C++
libzthread-dev - Object-oriented synchronization library for C++
msn-pecan - alternative MSN protocol plug-in for libpurple
msn-pecan-dbg - debugging symbols for msn-pecan
neverputt - 3D miniature golf game
neverputt-data - data files for Neverputt
php-hamcrest - This is the PHP port of Hamcrest Matchers
python-execnet - rapid multi-Python deployment (Python 2)
python3-execnet - rapid multi-Python deployment (Python 3)
scap-workbench - Scanning and tailoring tool for SCAP content
singularity-container - container platform focused on supporting "Mobility of Compute"
</code>
I even made sure my sources repo was fine
<code>$ cat /etc/apt/sources.list
deb http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi
#deb http://plug-mirror.rcac.purdue.edu/raspbian/ stretch main contrib non-free rpi
# Uncomment line below then 'apt-get update' to enable 'apt-get source'
#deb-src http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi

$ cat /etc/apt/sources.list.d/raspi.list
deb http://archive.raspberrypi.org/debian/ stretch main ui
# Uncomment line below then 'apt-get update' to enable 'apt-get source'
#deb-src http://archive.raspberrypi.org/debian/ stretch main ui
</code>
Yes I did do an sudo apt update prior to the me attempting to install barrier
Does anyone have idea to fix this issue?
Comment: perhaps you need to be running **buster** rather than **stretch**
Answer: Install Raspberry Pi OS which has barrier in its repository.
You could try downloading from the barrier website.

E: Unable to locate package barrier


Can my water heater's relief valve discharge line and drain pan line merge into a common pipe?

Question: Currently, I only have a T&P relief discharge line that runs down to just above the pedestal and out through the exterior wall. I would like to install a drain pan under the water heater.
I want to cut my relief discharge line and install a tee in order to connect my drain pan's line and allow both to exit using the existing pipe. My concern is that this might allow water flowing down from the relief valve to flow back into the pan and overflow it.
Is this a recommended solution?
Answer: The answer is no. This configuration would most likely fail multiple code requirements.
Explanation
You do not mention the diameter of the current discharge pipe, the distance that it runs, how many changes in directions there are, and where it terminates, so I cannot provide a complete answer. However, I can confirm that it would be against code to directly connect the two pipes together due to the resulting cross-connection between a potable system and a drainage system.
The pipe that drains the pan is considered part of a drainage system (either sanitary or storm, depending on what it connects to or where it terminates). The T&P relief valve's discharge pipe is connected directly to the potable system and as such is
considered as part of the potable system. It is against code to directly connect these two systems as the resulting cross-connection allows for the potential of the potable system becoming contaminated.
In addition, there are pipe diameter requirements to be considered.
In a typical installation, the relief valve's discharge pipe terminates indirectly above the drain pan's drain opening with an air break that prevents the two systems from being cross-connected. The requirement for a drain pan's drain pipe is that it be 2 times that of the relief valve's discharge pipe diameter.
I assume that the diameter of your T&P relief valve's discharge pipe is the same size as that of the T&P valve's outlet connection, therefore this pipe cannot be used as the drain pan's drain pipe, unless you increase the size of it.
Suggestions

You could repipe the drain line to outside in a larger diameter and install the drain pan and T&P discharge pipe as outlined in the below code requirements. (Note that if your drain is to discharge outside above grade, that in addition to it being located in a safe place to prevent anyone from being burned, you should also put some sort of screen protection on the end of the pipe as this pipe will create a direct opening into your home via the drain pan's opening)
If the water heater is located in an accessible location, the combination of periodical visual inspections and turning off the tank and shutting off the water supply when being away on vacation, will prevent most issues with water damage from a failed tank. In addition, replacing the anode rod as outlined in the tank's literature will prolong the life of the tank.
If you are really concerned about water damage from a leaking tank, there are many leak detection systems that when sensing a leak can shut off the water supply.

Code Requirements (Based on the Canadian Plumbing Code)
Relief Valves
Every hot water heater mush have a pressure relief valve and a temperature relief valve. The two can be combined in one device so long as it meets the requirements for both individual valves:

operates when the pressure inside the tank reaches the rated pressure of the tank
located so that the pressure in the tank cannot exceed the pressure in the tank by 35 kPa (5 PSI)
located within the top 150mm (6") of the tank
is designed to open and discharge sufficient water from the tank to keep the temperature of the water inside the tank from exceeding 99°C (210°F)

Relief Valve Discharge Pipe
The requirements of the relief valve discharge pipe are that is must:

be of a size at least equal to the size of the outlet of the valve
be installed ridged
be piped so that it is sloped away from the valve
terminate with an indirect connection above a floor drain, sump, or other safe location
have an air break not smaller than the diameter of the discharge pipe but with a minimum of 25mm (1") or a maximum of 300mm (12")
have no threads at its outlet
be capable of operating at a temperature of not less than 99°C (210°F)
have no shut-off valves installed on it

In addition, if the relief discharge pipe is longer than 2m (6' 6") or if more than two 90° elbows are used, the valve manufacture's installation instruction must be followed to ensure that the piping does not restrict the valve's discharge capacity.
Drain Pan Requirements
A drain pan is required when a hot water tank is located in a ceiling or roof space, or over a floor of wood construction. The requirements of the pan are:

be not less than 50 mm (2") larger than the tank
have walls not less than 25mm (1") high
be drained by a pipe two sizes larger than the relief valve discharge pipe
have a drain that is located directly under the relief valve discharge pipe that drain directly to a floor drain or other accessible location

Typical Hot Water Tank, Relive Valve, and Drain Pan Configuration:
<code>           ___
   _______|_  |
  |         | |
  |         | | <— T&P Discharge Line
  |   HWT   | |
  |         | |
  |         | |
  |_________|     <— Air Break (end of pipe to top of pan wall)
|_______________| <— Drain Pan
             |  ____________ <— Drain to Sanitary or Storm System
             |_|
</code>
Note: if the drain pan's drain connects to a sanitary system, a p-trap (as shown) is required. In addition, the p-trap would require a trap primer.
Comment: Being considered part of the potable water system definitely explains why the T&P discharge line terminates above the drain pan.
Comment: Hydronic heating where fed by a potable system can use a backflow preventer (double check valve I think) to avoid contamination. Is there any equivalent to this approach for these types of DWV situations?
Answer: No, they must be independent. SO says the plumbing code book at Lowes, I'm facing a similar issue, but it's from my sump pump from the mini split to the outside, which I was hoping to tie into the water heater or another discharge line.
Discharge is one per unit, and can not be merged, can't be dumped into public walkway (sidewalk, driveway), not into DWV (I have no clue why not)
Comment: In your case, are you referring to connecting condensate drainage from a mini split into another drainage system?


Why did my avatar change?

Question: My network-wide gravatar identicon used to be a pleasant blue, now it's bright green. I didn't change my email. Did Stack Exchange change its email hashing algorithm or something?
Comment: Happened to me too. Has anyone reported this bug to gravatar?
Comment: @rene It's actually a cross-site dupe of my [MSE question](http://meta.stackexchange.com/q/283643/323179). I've done a bit of research if you look at my question. Also note that I see the right icon, since it depends on where your IP address is.
Comment: Actually, [the comma splice here](http://meta.stackoverflow.com/revisions/332880/4) is grammatically incorrect. The two parts of this sentence (before and after the comma) are actually complete phrases, and independent clauses cannot be separated by a comma alone. You need either a coordinating conjunction (*e.g.*, and, but, for, so, yet, nor), or a semicolon that serves the same role. So this *is* an issue of grammar, but I'm electing to leave a pedantic comment instead of re-editing the post because you are entitled to a certain degree of personal expressive freedom. :-)
Comment: It seems there is something going on with your account. There is activity visible on multiple sites, yet your SO profile doesn't show it? Did you have multiple accounts by any chance? Did they get merged?
Comment: @Bart just to keep track of issues that seem related, at least in appearance, [this was reported yesterday on MSE](http://meta.stackexchange.com/questions/283659/cannot-access-the-per-site-metas-of-only-a-few-se-sites#comment919395_283659) although  an account merge was involved there.
Comment: See: http://meta.diy.stackexchange.com/questions/1218/hmm-something-funny-with-the-what-do-they-call-it-gravatar/1219#1219
Comment: Seems that it might be a general phenomenon. If I go to edit profile page I can see to different avatars, one on the toolbar and one editable in the profile settings. I think Laurel cross-site dupe, gives a lot of insights.
Comment: @barron Stick your stackoverflow profile URL in to archive.org. Check out an old version of your profile, right click the avatar and save locally. Then upload to SO.
Comment: Sorry for the "me too", but "me too!". My actual picture disappeared and the gravatar is different than what I had before my actual picture. Weird.
Comment: This happened to me now.... ?!?!
Comment: @Bart Not as far as I'm aware. I do have several of my network accounts set to "hidden", though.
Comment: Okay, because your SO account seems to show only SO, while on Meta here I see some posts on other sites in your profile. And when going to those sites, I see a more extensive network account.
Comment: Related MSE question - http://meta.stackexchange.com/questions/283643/why-is-my-profile-image-different
Comment: I am having the same problem. On a related note, what hashing algorithm does SO use? I've tried both MD5 and SHA1 on my email address and username and neither produce the hash that my gravatar uses.
Comment: As of 2023, gravitar icons do differ from the previous versions. I did not check the exact dates, but icons did change between 2019 and 2022 (based on a quick check I did on my own profile).
Answer: It seems a gravatar problem, not related to Stack Overflow.
Your big avatar (https://www.gravatar.com/avatar/efef01b733b5e8af2d8670efe6990e90?s=328&d=identicon&r=PG) is bright green:

Your small avatar (https://www.gravatar.com/avatar/efef01b733b5e8af2d8670efe6990e90?s=32&d=identicon&r=PG) is more bluish:

Note the hashes are identical, so it's not a change in the email hashing algorithm.
Comment: I tried reporting this issue to gravatar but their contact form seems closed. Someone from SO should communicate this issue to gravatar people IMHO.
Comment: And it's gone! Looks like the cache for the smaller one has been purged now as well.
Comment: My avatar changed too and it looks completely different, but the weird part is that only one of my 2 computers. On one of them it still shows as usual.
Comment: Aaarghh!!! My avatar just changed too
Comment: @gre_gor Size matters, [128px](https://www.gravatar.com/avatar/efef01b733b5e8af2d8670efe6990e90?s=128&d=identicon&r=PG) is bright green.
Comment: Photoshop will fix that right up for you.
Comment: Yeah my avatar just changed too ?!
Comment: And mine! It's horror.
Comment: http://shouldiblamecaching.com/
Comment: Also happened with me. My old gravatar was yellow-brown. My new one is light blue.
Comment: And gravatar's fix replaced all avatars. They're both green now :D
Comment: Both your URLs show the bluish avatar. Looks like the URL with a `r=PG` parameter returns the bluish avatar and without the parameter, the bright green one. Size doesn't matter.
Comment: The only blue one seems to be of 32 px size, perhaps one could blame caching (in this case, commonly accessed sizes having longer life spans).
Comment: my avatar also changed from rose to blue
Comment: Mine was a green one like the one posted and it was that way across all StackExchange networks until today; now it's a yellow one on StackOverflow and completely different dark green one on SuperUser .. I say StackExchange and/or gravatar need to embrace this issue and just have any default profile pics be random across the board and for each login .. makes the Q&A more colorful
Comment: @CainNuke: This is because of caching. I pressed Ctrl + F5 in my Firefox and my avatar changed to different on 2nd computer as well.
Answer: No.  Stack Exchange did not change its email hashing algorithm or something.
In the mean time, thought I would post this as a workaround until Gravatar stops having a meltdown.
Copy your Stackoverflow profile URL in to archive.org. Check out an old version of your profile, right click the avatar and save locally. It should be a nice high res version. Then upload to SO.
Comment: Thanks. This saved [me](http://meta.stackoverflow.com/q/333506/3785314) today.
Comment: @barron Hold on, let me edit my answer to address the very clear question you asked.
Comment: That was actually a **really** good answer. It worked for me. Never occurred to me that you could look up a historic version and grab the image.
Comment: Thanks!  This has really bothered me.  After finding your answer, I actually searched to see why I couldn't award you a bounty.  (Can't on meta - baa).
Comment: Does not address the question.
Comment: my avatar changed recently for some reasons and your post helped me fix it.
Answer: As others already pointed out, the problem is caused by Gravatar not Stack Overflow.
As a workaround I used google to search for my profile image with the query stackoverflow my_username.
Luckily Google caches (most) images on the results page.
Comment: Well the other answers already address the question. This answer is meant for anyone who wants a workaround to fix the problem.
Comment: I tried this before making my [post](http://meta.stackoverflow.com/q/333506/3785314) but it did not work. You have to be careful because there are many many images from Gravatar that look alike. If you really look closely, you will realize that they are not the-same. Some are brighter images, some are darker.  Google search result returned very similar images but I compared them to my old one(low quality) and they were **similar** but not the-same. The best way to do this is to simply use archive. You will find your original image.
Comment: Does not address the question.
Answer: My gravatar as displayed by SO has also changed recently, though I have neither altered my SO or gravatar profiles.
I notice that SO is selecting the PG-rated version of my avatar, per the r parameter at the end of the url:
https://www.gravatar.com/avatar/f057f53afd6fffc5075d8d59277cd103?s=48&d=identicon&r=PG

Unsurprisingly this URL as-is yields the anonymous geometric design.
I need to go dig up the relevant login so I can't yet confirm, but I recall marking my avatar as rated G.  If I change the parameter to G then I get my G-rated face:

I also get my face if instead I merely down-case PG to pg.
So it seems either SO has added, changed or even just up-cased this GET parameter recently, or gravatar has introduced a fǝature where requests for rating PG are no longer equivalent to those for pg.
Particularly, they break case-insensitivity in their claim:

To allow images rated G or PG use something like this:
https://www.gravatar.com/avatar/205e460b479e2e5b48aec07710c08d50?r=pg
Comment: Same problem here, changing to lowercase pg fixes it. Shouldn't be this a separate bug report?
Comment: Hmm apparently it seems to be a caching problem on gravatar's side; changing my gravatar to rating X, and then after a while back to G fixed the issue. Probably the uppercase/lowercase thing just forced the lowercase one to be generated (bypassing the broken cache).
Answer: I would like to add that this does not just affect Identicons but also uploaded Avatars hosted by Gravatar.
while fixed now (at least for me), for the most part of yesterday my size 48 avatar image was returning a 502 - Bad Gateway (and this was on 2 different computers on 2 different networks, work and home)

however another user's gravatar image at size 32 was giving a 502 - Bad Gateway while mine wasn't

so yeh if you like your avatar not to be buggy like this and you don't want to wait for Gravatar to get their crap together (seriously duplicate Meta questions keep coming up about the identicons, how is it not fixed yet?) your best bet is to go to Edit Profile & Settings >> Edit Profile, click on the avatar and upload it to https://i.stack.imgur.com (since if that goes down so does mostly every image in the questions/answers)
Downloading your Avatar
if you've used a non-identicon avatar and didn't delete the original image just upload it. otherwise go to the Gravatar url where your avatar is coming from (generally right click and open image or inspect the HTML and get the URL from that) and alter the s= argument to get your desired size. hopefully you don't get a 502 for the size you want.
the largest size used on Stack Exchange, to my knowledge is 328 which is used in the Profile Page (this is resized down to 164 but the url is pointing to 328)
Comment: There is a problem with the images uploaded to http://i.stack.imgur.com as well. I uploaded my avatar today (first time that I'm using a custom non-identicon avatar) the way you mentioned and it's different [here (328)](https://i.stack.imgur.com/ESoqk.jpg?s=328) and [here (48)](https://i.stack.imgur.com/ESoqk.jpg?s=48) - looks like a misbehaving downsizing algorithm to me

Why did my avatar change?


Is a gas fireplace enough to heat a small cottage?

Question: I have a ranch style 544 sq foot cottage 16x32 it is long and very narrow. I would like to install a gas fireplace for a heat source but as well as the ambiance. Do you think with proper blown in insulation, new windows that a gas insert would work. I like a nice 72 degree house. I have several new ceiling fans with high catherdral ceilings so it is like a two story without the usable second story. Any suggestions would be helpful. I understand I need to have a rather large unit (btu) due to the high ceilings, just want to be sure that this will be efficient. I plan to purchase a good blower and wall thermostat as well.
Comment: If you're going to use it that intensively, make sure exhaust is vented to outside (after passing thru heat exchanger/blower). For casual decorative use, it's not uncommon to ignore CO/CO2; for heating purposes, you really can't.
Answer: I'd talk to the Fireplace dealer/installer to confirm, but yes, that should work provided:

you use a blower (sounds like you have)
your house isn't chopped up into too many rooms
given the high ceilings, I'd strongly suggest installing a ceiling fan as well to help. If you don't, you may end up with one really hot room, and a bunch of only 'warm' rooms.


Determine the expected size of a lower triangular sub-matrix of a random matrix?

Question: Consider a $N\times N$ random matrix $A=[A_{ij}]$, whose elements are independently randomly chosen from the binary field $\mathbb{F}_2=\{0,1\}$ with probabilities $p_0=p$ and $p_1=1-p$. Suppose that we are allowed for rows and columns reordering on $A$ to transform it to the form
$$
A = \left[\begin{array}{cc}L & A_1\\ A_2 & A_3\end{array}\right]
$$
where $L$ is a lower triangular sub-matrix. My question is: is that possible to determine the expected size of the largest $L$ (as a function of $N$ and $p$)? Can anyone point me to some references if there is any. Thanks sincerely.
Answer: A reasonable first estimate is $\ell$ (the size of $L$) is approximately $4\log n/|\log p|$.
To get this, consider choosing a sequence of $k$ rows $i_1,\ldots,i_k$ and $k$ columns, $j_1,\ldots j_k$. There are $n!/(n-k)!\approx n^k$ ways of choosing the $i$'s and the same number of ways of choosing the $j$'s. There are therefore approximately $n^{2k}$ choices of a sequence of $k$ rows and a sequence of $k$ columns.
For each choice $(I,J)$, you look at the submatrix $L^{(I,J)}$ with entries
$L_{a,b}=A_{i_a,j_b}$. This is lower triangular precisely when $A_{i_a,j_b}=0$ for each $b>a$. For a fixed choice $(I,J)$, the probability that $L^{(I,J)}$ is lower triangular is $p^{k(k-1)/2}$. Hence the expected number (using linearity of expectation) of choices of $(I,J)$ such that $L^{(I,J)}$ is lower triangular is approximately $n^{2k}p^{k(k-1)}/2$.
Since there is enough independence around, you expect a lower triangular submatrix of size $k$ when $n^{2k}p^{k(k-1)/2}>1$. Taking logs, you obtain the bound $k>4\log n/|\log p|$.
A good reference for this kind of argument is the book "The Probabilistic Method" by Alon and Spencer.
Comment: Anthony, few remarks. i) For your first approximation, you assume $k/n$ is small. ii) The last inequality is $k<4\log(n)/|\log(p)|+1$. iii) About your "Since there is enough independence around": a choice $(I,J)$ means, in particular, a choice of the orderings of $I,J$. Then if you keep the sets $I,J$ and change only the orderings, you are far from independence, except again, if $k/n$ is very small, that is, if $p$ is small.
Comment: I interpreted the question as being about the large $N$ / fixed $p$ limit. Similar problems with dependence arise if you try and find the largest clique in a random graph, but there (as shown in Alon+Spencer), even though many of the same edges are used, there's enough independence to make the 2nd moment method work.


Weight Loss after reaching a plateau

Question: I am a 46 year old male (Height 170 cms and Weight 179.7 lbs) and I have just been diagnosed as Type 2 diabetic two months back and put on a mild oral medication by my doctor. I prefer exercising outdoors and my daily routine (6 days a week) includes 5 mins of stretching, 30 mins of brisk walk, 25 mins of bicycling, 10 mins of skipping and 10 mins of breathing exercises. However, despite of my following this routine for last few months I am unable to loose weight below my current weight. I have lost inches around the waist but I still need to loose some weight. I am a vegetarian and I follow a controlled diet with no sugars. Really would appreciate if someone can help me on this...Thanks..
Comment: Have you considered running or lifting weights?
Comment: Do you feel more toned or see other indications that you are losing weight?
Comment: Thanks and Appreciate the answers by Dave Liepmann, Kneel-Before-ZOD and JohnP
Answer: "I have lost inches around the waist but I still need to loose some weight"
If you've lost inches, you've lost fat mass, what is good. If you've lost fat mass and haven't lost weight than you've gained muscle mass, what is also good.
Why do you believe you need to loose 'weight'? is it something you convinced yourself of, or did your doctor tell you to? If you are to fat, than you are on the right track, you're exchanging fat for muscle and your waist measurements combined with your stable weight are evidence of that.
If your doctor tells you to lose weight and he/she knows you started doing almost a full hour of exercise on average per day, he/she should know that your total body weight at this moment isn't a reliable indicator of how your fat percentage is doing. If he/she doesn't realise that and tells you to loose 'weight' rather than 'fat mass', than its time you look around for an other doctor who understands you can get leaner and healthier from doing exercise while not loosing or even actually gaining weight.
A controlled diet without sugars is always good, even if you weren't a diabetes. Being a vegetarian kinda complicates things there though. The best diet for loosing fat, especially as you have type 2 diabetes is a low-carb diet. How strict a vegetarian are you? If you do eat fish, you may want to consider going for a low-carb or even a keto diet. If you don't eat fish, keto might be impossible and low-carb difficult, but I'm not quite sure there.

Weight Loss after reaching a plateau


Windows File Sharing not working

Question: We have a workstation on our domain that we need to share a printer from, and it's not working.  I also set up a shared folder to help with testing.
Details:
We are on a domain.  All operations performed by a domain admin account.
Group Policy has the following related set:
Policies > Windows > Security > Windows Firewall > Domain > Firewall State:  ON
Policies > Admin Template > Network > Network Connections > Windows Firewall > Domain > "Allow inbound file and printer sharing exception": Enabled, with specific ip addresses listed.
The workstations is running Windows 7.
The workstation has File & Printer Sharing Service installed.  All the required services (TCP/IP Netbios, workstation, server, ssdp, upnp, network connections, network location, computer browser) are running.
From the workstation itself, when I point Windows Explorer to its own URI (\workstation) I can see the shared printer and a shared folder.  I cannot open the shared folder, even though both its NTFS & share permissions are set to Everyone Allow All.  The error Windows Explorer gives you is: "the remote device or resource won't accept the connection."
From the domain server, which has an IP address listed to be allowed in the Group Policy above, I cannot even connect to the workstation from the Windows Explorer.  It errors out saying "Windows cannot access \workstation"
It should be noted that other machines on our network are able to have their shares viewed just fine.
Ideas welcome.
Thanks in advance.
Comment: Does the workstation have an administrator password setup, it must!
Answer: Workstation rebooted and seemed to figure itself out.  It may be that, even though gpupdate/force had been run on the machine numerous times, it wasn't applying new policy as it should have been.  But it's working now.

Windows File Sharing not working


What are the different sub schools of Advaitha?

Question: I have heard that there are three subschools of Advaitha Vedanta.
They are
1. Varthika
2. Vivarana
3. Bhamathi
Are there more sub schools?
Can you briefly summarize the main philosophical differences in the schools?
Answer: The idea that these are hard and fast 'schools' can be misleading. These are all highly diacritical streams of logical argumentation of the Advaita as taught by Adi Sankara. Many of the ideas in each are the same. Three of Sankara's disciples were Padmapada (who wrote the Pancha-padika and whose disciple Prakashatma wrote the Vivarana commentary), Sureshvara (Vartika), and Vachaspati Mishra (Bhamati commentary). Although scholars and others often refer to them as schools, it is best to understand that all three draw upon Shankara and his writings. Most of the 'differences' are specious arguments; all three use Shankara as reference. Except for the sake of pure argumentation, does it matter whether Advidya arises from a cosmic standpoint or an individual standpoint? Avidya is Avidya. From the standpoint of Brahman both viewpoints are non-existent. Sharma, in his book The Advaita Tradition in Indian Philosophy: A Study of Advaita in Buddhism, Vedanta, and Kashmira Shaivism, says p 222:

...But really speaking, the two schools [Vivarana and Bhamati] are not opposed. Both the schools agree that Isvara is ever free from ignorance and that in Him sattva predominates. Hence, whether concealment and projection are treated as as two aspects of the same power or the former is called avidya and the latter maya, the difference is only in words.

Sharma, quoting Shankara, says (A Critical Survey of Indian Philosophy, p 288 - https://archive.org/details/IndianPhilosophyACriticalSurvey):

...Shankara remarks that reasoning, because it depends upon individuals, has no solid foundation. Arguments held valid by some, may be proved fallacious by others more ingenious. ( Shariraka-Bhasya, II, I, 11)

The commentators after the above mentioned 3 'schools', focused on the Vivarana and Bhamati streams. Some of their differences are dependent upon Shankara's similes and metaphors of the rope/snake, universal space/space in a jar, shell/silver, water/waves, etc, etc. It should be remembered that these are metaphors. Sharma cautions (p 228, Advaita Philosophy in Indian Philosophy):

...are suggested for their value and should not be taken literally and woven into theories...

and p 229:

Really speaking, the distinction among Ishvara, jiva, and saksi is valid only in empirical life; ultimately all the three are Brahma itself. Ishvara, jiva and jagat are appearances projected by maya, they arise together and they vanish together when maya is canceled.

Swami Vivekananda says (Complete Works, V7, pp164-5):

For this reason, nescience [avidya, or maya] has no absolute reality. You can call nescience neither real nor unreal; "Neither real, nor unreal, nor a mixture of both". About a thing that is thus proved false, neither question nor answer is of any significance. Moreover, any question on such a thing is unreasonable.

Another book on the same subject is Bhamati and Vivarana Schools of Advaita Vedanta: A Critical Approach by P.S. Roodurmum usually available here - https://www.mlbd.in/
Comment: Good points! I believe these sub-schools are only engaging in semantics debates without necessarily contributing anything new to the fundamental anubhava which is stressed by Shankaracharya. His own definition of Avidya in his bhashya is plain and simple and practical.
Answer: After going through lot of research i finally got the results in my hand i am putting references on the last because Advaita Vedanta is very vast to study.
"And I have to say this is a very brilliant question"
Advaita Vedanta is believed to be one of the classic paths to spiritual realization in Hindu tradition.
Advaita Vedanta is the oldest extant sub-school of Vedanta
There are only three sub schools of Advaita Vedanta:
let's see in general what are the three sub-schools of Advaita Vedanta.
1) Bhaamathi Prasthaana
Bhamathi sub school bases itself on the Bhamathi sub commentary of Vachaspathi Mishra on Sankara's Brahma Sutra Bhashya. Scholars opine that there was an advaitin Mandana Misra who was a contemporary of Sankara and wrote the work Brahma Siddhi. The means propounded by this Mandana Mishra in his Brahma Siddhi (independent work) is different from Sankara and traditional Advaita Vedanta. Thus there are differences of opinion on this (many places Sureshwara too refutes the views of Mandana Mishra in his Naishkarmya Siddhi) (Sankara's and Mandana Mishra's means to the final goal of Advaita). Vachaspathi Mishra wrote the first complete commentary on Sankara's BSB titled Bhamathi (there was Panchapaadika of Padmapada acharya but this work analyzes only the first four sutra bhashyas (but there are proofs from Bhamathi that Padmapada had written an entire commentary on Sankara's BSB and Madhava vidyaranya's Sankara dig vijaya too tells it the same way – but scholars differ on this). Scholars thus opine that Vachaspathi tried to harmonize Sankara with Mandana Mishra – thus in many places, he uses Brahma Siddhi means which might seem to be against Sankara's means. Even in some places, vachaspathi goes against Sankara's bhashya to interpret in a different way which is supported in Amalananda's Kalpatharu sub-commentary on Bhamathi (it is interesting to note that Prakataartha Vivarana of Anubhooti svaroopacharya refutes the places where bhamathi goes against Sankara - but the views of this acharya is refuted and bhamathi supported by Amalananda). It finally ends up in Appayya Dikshitar's parimala sub commentary on Kalpatharu where dikshitar supports Sankara while refuting Bhamathi in those places. Enough of this too much explanations ---- this sub school is based on Bhamathi mainly and Kalpatharu-Parimala secondarily to interpret Bhamathi properly. This is the first sub-school of Advaita Vedanta. There are less number of followers for Bhamathi school these days (most followers are in north I believe) but still it is interesting to note that Gauda Brahmananda Saraswathi in his Nyaaya Ratnaavalee on Siddhanta Bindu of Madhusudana Saraswathi says that Vedanta shaastra includes the five works of Brahma Sutra, Sankara's Brahma Sutra Bhashya, Bhamathi, Kalpatharu and Parimala. It is generally held that there are very few who have read all the five works and mastered them (the entire five works are published by Nag Publishers in two volumes for 400 Rs. Chaukhambha Press too have brought out the five works for 650 Rs.).
2) Vivarana Prasthaana
As mentioned earlier, Padmapaada had written Panchapadika on Sankara's Brahma Sutra Bhashya which was again explained in detail by Prakaasaatman in Panchapaadika Vivarana. There are many sub commentaries on Vivarana of Prakaashaatman. The school which bases itself on Vivarana of Prakaasaatman is called Vivarana school. The important sub commentaries on Vivarana are Akhandaananda Tattva Dipana and RjuVivarana of Sarvajna Vishnu – there are as well sub commentaries on it by Chitsukha and Nrsimha ashrama. Amalananda has also written Panchapaadika Darpana. This school is very famous and has many acharyas following it. Two of the three complete commentary on Sankara's BSB (one being bhamathi) follow Vivarana school only – these are Anandagiri's Nyaaya Nirnaya and Govindananda's Bhashya Ratna Prabha. We can very clearly say that this school bases on one of Sankara's direct shishya or disciple (Sachidanandendra Saraswathi does show in some work that this school differs from Sankara's BSB but it is worthy enough to analyze on that – might be we can take that up for Ph. D when lot of free time is there).
3) Vartika Prasthaana
Sureshwaracharya, after being guided by Sankara, wrote vartikas on Sankara's Taittiriya and Brihadaranyaka Bhashyas. Vartika is that commentary in which ukta, anuktha and duruktas are mentioned – ukta is explaining in detail whatever the original work does – anuktha is explaining that which has been left out in the origin – duruktha is making correct whatever has been explained either wrongly/incompletely in the original work. Sureshwaracharya thus differs in almost 4-5 places in the Brihadaranyaka Vartika from Sankara's Brihadaranyaka Bhashya. The Brihadaranyaka Vartika consists of as much as 12,000 slokas which has been further commented by Anandagiri and vidyaasagara. Vidyaranya has condensed the vartika into a work called Vartika saara. The school based on Vidyaranya's as well as Bharathi Teertha's works (which themselves base on Vartika of Sureshwara) is called Vartika school. We can thus very well clearly find differences between ishwara in vivarana and this school. Vivarana considers ishwara as Bimba Chaitanya (that original consciousness which is reflected and becomes jeevas) whereas vartika school considers both ishwara and jeeva as illusory and not real at all (this is clearly found in Panchadashi many places). But we have to remember that Vidyaranya and Bharathi Teertha have written vivarana prameya sangraha which is summarizing Vivarana of Prakaasatman where they follow the vivarana school very clearly. I have also found in one place in panchadashi where vidyaranya refutes bhamathi view of jeeva.
advaita vedanta : https://en.wikipedia.org/wiki/Advaita_Vedanta
sub-schools of advaita : http://jeevaaspervarioussystems.blogspot.com/2006/09/different-sub-schools-of-advaita.html
Comment: The answer is good from historical perspective, I was looking for an answer which summarized the philosophical differences. What exactly are the philosophical differences between these schools?
Comment: There is no philosophical difference between these three, they are just different modes of explanation of Vedanta darshana. Bhamati school is related to brief high level explanation, Vivarana is like Prakarana format where the essence of the Darshana is represented. Vartikas refer to sub-commentaries where Sureshvaracharya tries to explain the view points of Adi Shankaracharya in simpler terms. So all three are equal in terms of philosophy but serve different purpose with respect to their explanation format.
Answer: The various authors for the schools are given below.
Bhaamati school:
vAcaspati miSra - bhAmatI
amalAnanda - kalpataru
appayya dIkshita - parimala
lakshmInRsimha - Abhoga
allAla sUrI - bhAmatI tilaka
SrIranganAtha - bhAmatI vyAkhyA
VivaraNa school:
padmapAda - pancapAdikA
prakASAtman - vivaraNa
amalAnanda - darpaNa
nRsimhASrama - vedAntaratnakoSa
dharmarAja adhvarIndra - padayojana
Unlike other schools, one of the tenets of advaita is that there are three satyas

prAtibhAsika satya (Illusory reality)
vyAvahArika satya (Empirical reality)
pAramArthika satya (Absolute reality)

Main points of difference between Bhamati and Vivarana schools
Bhamati says there are many primal ignorance but Vivarana says there is only one primal ignorance with difference modes.
According to Bhamati, rhe study of vedas and performance of yagnas leads to chitta suddhi and desire to know Brahman. But according to Vivarna, this can lead to desire to know Brahman and subsequently jnana.
Bhamati school says that mind is the instrument of realization but vivarna says that just by hearing the mahavakya, a conditioned purified mind can attain jnana.
The limitation theory is propounded by Bhamati. In this theory the jiva is a delimitation of consciousness by the internal organ, while Ishvara is not so limited. Reflection theory is adopted by VivaraNa. According to this, jiva is the reflection of Ishvara who is the bimba or the original in avidyA.
Bhamati has no injunction for doing Shravana. The vivarna school does not agree with this.
Finally the most important difference, Avidya has jiva as locus and the
conditioned Brahman as content in the Bhamati school but Avidya has both the unconditioned Brahman as both locus and content.
Source: Bhamati of vacaspati misra and vivarna of parakasatman (available in archive.org)


Question structure in Esperanto

Question: Does every question in Esperanto have to be formed with ĉu or one of the ki- words (kie, kio, kiam,... etc) ?
Answer: The answer is no. This is discussed in PMEG, section 22.3, Demandoj sen demandovorto.
They normally take one of two forms:

Sentence fragments, usually 2-3 words: Via nomo? Efektive? Sed la teo?
Declarative statements with doubtful nuance: Do vi ne deziras teon? Kaj pro tio vi perdis la bileton?

In these situations the question-word is being omitted for the sake of conversational neatness: they could be rephrased as Kio estas via nomo? Ĉu efektive? Sed kiel estu la teo traktata? etc.
Comment: How about the following?  Would this be incorrect: "Ŝatas lerni?  Volas lerni alian lingvon?" I saw someone post something similar to this on Facebook a while back. It seems the subject "You" is implied.
Comment: It is permissible if the intended subject is really obvious. However, it cannot be done all the time, as the absence of a subject can change the meaning of the sentence: for example, *Ŝi estas infano* means "She is a child" but *Estas infano* means "There's a child."
Comment: I understand. The person who posted that way had mentioned elsewhere that he was fluent in Esperanto, so I thought maybe he knew something I didn't.

Question structure in Esperanto


Is sump pump supposed to discharge back onto property or onto the street curb?

Question: I have a sump pump in my basement that discharges several times a day. Currently, it discharges water right next to my front steps. I read that sump pumps should discharge at least 10 ft away from the the home to avoid damage to the foundation. Mine is definitely too close to my house, and I am getting water in the basement, possibly from my own sump pump discharge. I called my town to get a permit to run my sump pump under the sidewalk in front of my house so it discharges out to the gutter. They told me this was illegal and that sump pump should discharge back to my own property. This doesn't make any sense to me, especially since almost all my neighbors and even the town library run their sump pumps under the sidewalk and discharging water to the gutter! I have seen other towns do the same setup. I want to go to back and tell them this. If However, if I tell them that my entire block has their pumps to the curb, what might happen? Might they come and fine everyone? Can I make a case for myself that I should be allowed?
Comment: Well, it needs to discharge *far enough away that it doesn't come back into the house*.  That could be 2 feet away or 2000, depending on the lay of the land.
Comment: Hello, and welcome to Home Improvement. Unfortunately, this is a legal issue, and so is probably  off-topic here; let's see what answers  you  get. And, you should probably [take our tour](//diy.stackexchange.com/tour) so you'll know how best to participate here.
Comment: I'm voting to close this question as off-topic because it's a legal question.
Comment: Hi mine just pools next to my front steps. That is an additional nuisance because in the summer months that little pool becomes a mosquito breeding ground.
Comment: @DanielGriscom is correct. If City Code does not allow discharge into storm system don't fight it. Look up rain gardens. You could turn it into a landscape feature. Allow the water to hit a pond and run out of the pond into a rain garden. The plants help the water infiltrate into the soil and can add significant wildlife features to the yard. Typical drainage law prohibits point discharge so don't put the pipe or any hoses too close to the property line (varies by law & district). Give it space away from the house but not on the property line (2-10 feet if possible)
Answer: You cannot make a case for yourself saying just because others do it you should be able to (just try that with a cop when getting pulled over for speeding)
What I have done in the past is to run the drain line to the curb and fill the last foot with gravel, when there is enough water it flows through the gravel and over the curb direct draining was not allowed, but this was legal, a big nosed neighbor trued to cause problems and called the city after I did this I did not get cited but several others on the block did, now every one has the same setup, makes no sense to me but if it flows out of the ground and over the curb it was legal in that city.
Comment: Running the sump line to the back of the curb will cause damage to the road just like it would a foundation. Perhaps worse depending on the depth of disturbed soil and the "tightness" of the storm joints. Likely what will happen is that the water will pool in the rock bed you created and move through the rocks & soil into a joint between the structure and the pipes taking sediment with it. This causes a constant sink hole behind the curb.
Comment: This is legal in town in several places where direct drainage to water he road way is not. It works exactly like a French drain , the soil and roadway are not affected because of the rock, note the first one I put in was at my grandmothers over 40 years ago, that spot is still wet regularly and the road has not been resurfaced in all these years.


Who inspects commercial aircraft seats for defects (and when)?

Question: Do inspections of aircraft seats occur only after passenger complaints, or do the major carriers conduct their own inspections at regular intervals?
Answer: Apart from what ymb1 and Zach Lipton mentioned, the passenger and flight crew seats are thoroughly inspected during the scheduled maintenance of the aircraft, in which the aircraft can be grounded for several days up to some weeks. Depending on how extensive is the maintenance check, the following items can also be inspected amongst others:

Condition of seat floor attachment fittings for tightness.
Reclining function, except those before and after the emergency exits (these must not recline at all).z
Removal of the seat cushions in order to inspect the seat structure.
Periodic replacement of all seat covers (washed or new).
Seat belts for condition, operation and proper attachment to the seat.
Life vests for presence, condition and expiration date.

Sometimes, when the repair is beyond the capability or the approval of the maintenance center it can be sent to a specialized seat overhauling center.
For more information and fun you can check the British Airways B747 D-check video
Answer: After every flight the cabin is cleaned and inspected. Cleaning requires opening and closing the tray tables, adjusting the seat positions, etc. Any fault will be detected and reported—in a perfect world. Some seats get more attention though, first and business class for example.
If something can't be fixed right away, it'll be on the to-do list.
Comment: Note that the speed and thoroughness of this cleaning and inspection will vary greatly between airlines and flights. Sometimes the cleaning may involve a very quick pass through the cabin to pick up obvious litter (maybe even done by the flight attendants as passengers exit) and sometimes it involves a careful inspection where tray tables are wiped down, seat pockets cleaned, etc... (especially if the aircraft remains overnight or when it will sit for hours before a long-haul flight).


Project Euler question

Question: I have a solution to one of the Project Euler questions that runs wicked slow, and I'd like to ask for suggestions to speed it up. However, the solution required a fair amount of analysis of the problem first. Before posting anything, I'd like to know what is appropriate in terms of providing analysis of the problem in my question.
Comment: According to [this thread](http://meta.mathematica.stackexchange.com/q/634/89), it is allowed to discuss PE problems / ask for solution here on _Mathematica_.SE. This might even be a duplicate of that question.
Answer: I think this is an excellent question. It is nice to keep the site tidy.
Perhaps you can split up your question into two parts. One about: is there a name for the techniques I am using, and one about the PE question itself. If you do, you should probably put them both on main. If it is a really theoretical analysis, perhaps http://math.stackexchange.com or another site may be more appropriate for the "background question".
You should realise that a question can always be edited or deleted, or even migrated.
If you disagree, please downvote, this is meta after all :)

Project Euler question


Exception in worker callback prevents queue item from being removed

Question: I have created a Drupal 7 module that utilizes hook_cron() and hook_cron_queue_info() to process some data, as well as use the module Ultimate Cron to handle scheduling when each runs.
hook_cron() is run every 15 minutes and it's job is to determine how much data needs to be processed and split it up into batches, creating a queue for each batch. As an example, say 1000 records, split into batches of 25, so you get 40 queues of 25 records each.
The queue is then processed every minute, so every minute it will process one queue item of 25 records.
The problem I am running into is that occasionally during the worker callback for a queue, when processing one or more of the 25 records, a record may result in an exception being thrown.
The exception is possible and expected, so I am handling the exception in a simple try/catch, so the queue is able to continue on and processes all 25 records. However it seems that if any of the 25 had an exception, the queue item does not get removed at the end like it does when there no problems. Ultimate Cron shows the queue as having started, but never finished and is still running (though really it is not, it got through all 25), and this prevents any further queue items from running.
This is not the behavior I would like, I want the queue item to be removed or "finished" regardless if an exception happened, because I have handled the exception(s).
I am unsure of what is deciding the queue should not be removed, is it drupal's queue api? Ultimate cron? Is there a way I can have it remove the queue manually at the end of the batch if there happened to be an exception?
Basic code:
/**
 * Implements hook_cron().
 */
function MODULENAME_cron() {
  MODULENAME_queue();
}

/**
 * Implements hook_cron_queue_info().
 */
function MODULENAME_cron_queue_info() {
  $queues['MODULENAME_queue'] = array(
    'worker callback' => 'MODULENAME_process_batch',
  );

  return $queues;
}

/**
 * Queue up batches.
 */
function MODULENAME_queue() {
  // Get the queue.
  $queue = DrupalQueue::get("MODULENAME_queue");

  // Only run if there are no items in the queue.
  if (!$queue->numberOfItems()) {
    // Get the full list of records.
    $records = MODULENAME_get_records();

    // Split the list of records into batches to process.
    $pager = 25;
    $batches = array_chunk($records, $pager);

    // Queue the batches.
    foreach ($batches as $batch) {
      $queue->createItem($batch);
    }
  }
}

/**
 * Process a batch.
 */
function MODULENAME_process_batch($data, &$context = NULL) {
  // Process a batch of 25 records.
  foreach ($data as $record) {
    MODULENAME_process_record($record);
  }
}

/**
 * Process a single record.
 */
function MODULENAME_process_record($record) {
  // Processing code here, this is where an exception can happen.
}

Answer: I have the same issue. For me putting everyhing inside the worker callback function in a try block solved the issue.


No file sharing between two server 2008 R2 machines

Question: I have just replaced XP with Server 2008 R2 on my test sever, and have been running 2008 R2 on my dev laptop.  When my server was still XP, file sharing just worked, but now it just doesn't.  I've enabled everything I can about sharing, and I can ping the server by machine name, but if I try an access a share, I get asked for a password.  The passowrd dialog assumes a domain for this user, but neither my laptop admin user nor my server admin user can get past this login.  What am I doing wrong?
Answer: Windows XP uses "guest only" file sharing, user accessing your file sharing will not be prompted for password. This kind of sharing although is convenience but introduce a dangerous security loopholes. In Windows Server 2003/2008, guest account is disabled and by default everything is disabled. You have to set NTFS, create share permission and more...
Good luck.
Comment: Plus, think about Windows firewall blocking share ports.
Answer: Have you set permissions for the share and NTFS permissions on the folder/files?
The fact that it is prompting you, means its probably working fine, just a perms/settings conflict.
The "standard practice" if you like, is to allow full access to "domain users" in the sharing, and selective permissions on the actual NTFS objects for more granular control. (Like some users no access to certain folders, others read only, others read/write, others append only etc.. you just can't do that with the sharing tool, but you can with NTFS, and you can use groups!)
If you can't get it, you can always enable auditing, it will quickly fill your security event logs with who/why.
Also, if you try several times, your account may get locked out, so check that too!


Yosemite: prevent 'Bring All to Front' behaviour on Command-Tab

Question: On Yosemite, using Command+Tab will bring all the windows of the selected application on top of everything else, similarly to using 'Window->Bring All to Front' when inside the application.
Note that Yosemite does manage interleaved windows, when manually clicking on background windows. It is possible to have two applications A and B, each with two windows each, and have (front-to-back) A1, B1, A2, B2 interleaved windows.
However, when using Command+Tab to select application A(or clicking on the application icon in the dock) will bring A1 and A2 on top of everything else.
It would be really nice to be able to only bring on top the last used window of a given application (namely A1), instead of all of them, hence preserving the interleaving of the other windows.
I'm not looking for Command-Tab to display all existing windows of all applications (like Witch, proposed in other answers), just not to bring all windows to front. and would like to avoid using Exposé/Mission Control (which requires more inputs).
Interestingly, I can already use SpotLight search with 'Terminal' for example, and this will bring the last active Terminal window in front, but not the other ones. This is what I would like to happen when using Command+Tab.
Do you know if there is any way to do this? I'm happy with some esoteric command-line solution.
Cheers,
Chaos
Answer: I had the need to run a terminal (to do git commits) over the top of another window (which shows diffs between files). I therefore ran in terminal...
<code>sleep 2; open -a Terminal
</code>
Then switched to the diff window with CMD+Tab. After two seconds, Mac OS X foregrounded the single Terminal window I was typing commands in.


Rideable mountain climbing mammal

Question: Mountain goats, and some other mammals, are exceptional climbers. They can climb slopes at greater than 60 degrees. Unfortunately they are too weak to carry humans or goods without serious injury risk. This lead me to wonder, is it possible that a beast sturdy enough to bear a human could be mountain dwelling and climb slopes of >60 degrees or is there a limit based on weight, size, shape or muscle that means a beast strong enough to carry a human could not climb these slopes?
Answer: Your big problem is if you start adding and taking away weight from a climber you throw off its balance, a rider will drastically shift their center of gravity and widens the animal, making steeper slopes much more difficult. breeding for size is not an issue, but drastically shifting the center of gravity and widening the animal is, especially for a goat like climber. put 50 degrees as your max and you will have much more success.
Answer: I think you want to move away from goats and look at monkeys. Monkeys and even the great apes carry their young on their stomach or their back. They can still climb, sloths do too btw. And Giant Sloths existed. They weren't tree dwellers but they could be changed into climbing mountains.
As John mentions in his answer, climbers without claws or hands rely on their center of mass to retain balance. Adding a moving rider to that is a recipe for disaster. So hooved animals are a poor choice here.
Answer: A takin might be able to do it.

from https://www.youtube.com/watch?v=q1VR9OMDdek
Takins are sturdily built.  Males takins can weigh 600-700 lbs and are 4 feet at the shoulder, which is comparable to a horse.  They live in mountains and can negotiate steep slopes.
I think a rider who does not want both of them to pitch over backwards when going up a steep hill could switch and ride underneath the takin, Odysseus style.
from https://thejosiasdotcom.files.wordpress.com/2017/04/odysseusram2.jpg?w=680

The existence of the song "Takin a ride" from the soundtrack of the movie Heavy Metal has defeated my efforts to search for instances of people actually riding takins.
Answer: You might be surprised at how steep a grade a horse & rider can climb.  I've ridden up & down slopes pretty close to 45 degrees myself, and I'm far from an expert.  Part of the trick is shifting your weight to keep the horse in balance.  You don't just sit in the saddle: in even a moderate climb, you shift your weight to balance over the front legs.  On a steep grade, you can be almost lying along the horse's neck.  On descents, just the opposite: you lean back to keep the weight on the horse's back legs.
For examples, do an image search on e.g.  "Tevis Cup Cougar Rock", and you'll find plenty of pictures like these: https://mfthba.com/wp-content/uploads/2014/11/cougar-rock-300x212.jpg http://www.horsesinthemorning.com/wp-content/uploads/2015/07/Karen-Chaton-Bo_Cougar_Rock_2013-1024x820.jpg
The real problem (other than keeping your saddle from slipping) is the footing.  Just as with humans, loose footing can make a slope difficult or impossible, not to mention dangerous for horse & rider.  I think, from the few times I've seen mountain goats in action, that they are not actually climbing a slope, but going from one small level ledge to the next.
Comment: Is the horse wearing an actual shoe in the second picture? o.O`
Comment: @a20: Yes.  There are devices for horses to wear rather than the standard nailed-on shoe.  They're generally called "boots" or "easyboots", after one popular brand.  There's a disagreement in the horse world as to whether it's better for the horse to have nailed-on metal shoes, or go "barefoot", but I'm not expert enough to have a valid opinion.
Comment: I'm sure the rubber-soled boots would have better grip than either nailed-on metal shoes or all-natural bare hoof, particularly for that rocky landscape (not to mention protecting the soft gooy center from sharp things). Mind, it'd have to be gripping the horse's foot pretty snugly to work well.
Comment: @Draco18s:  Yes and no.  On some kinds of rock the boots, or bare hooves, have better grip.  But on dirt (where I mostly ride) steel shoes seem to have the edge.  Also, if the sole of your horse's foot is soft & gooey, it is seriously ill.  The normal sole is quite tough (and like your feet, gets tougher if they go barefoot.)  You're actually more likely, most places, to have problems with small stones getting stuck in the grooves between the frog and the rest of the sole than with sharp objects.
Answer: As a general rule, mountain climbing mammals tend to be small, the largest being goats, donkeys, and bighorn sheep. They live in the mountains because they have found a niche with an unused food source, and no predators.
Anything larger either has to be a roaming herbivore that may not find the forage it needs to thrive on mountain sides, or a carnivore. The problems of trying to ambush prey with little concealement and carrying it off, all without falling off the mountain yourself, preclude large carnivores from being mountain dwellers.
Answer: I'm pretty sure what you are searching for is a Yak. They can carry heavy loads and even people and are very good in steep and uneven terrains. You see them all over the Himalaya mountains.

Rideable mountain climbing mammal