Are Parisian shops open on Sundays?

Question: I will be in Paris for a few days, including on Sunday. What can I expect in terms of public transport, shops, restaurants, etc? Is anything open, or am I meant to spend the days at home?
Comment: -1 for showing no research. What remains unclear after looking around online?
Comment: sadly, more and more shops do open in Paris/France on Sundays, which is untraditional.  in Paris all restaurants, tourism, and transport is completely open, it is a completely normal tourism day, you will have no issues whatsoever.
Answer: Many bakeries will definitely be open. Supermarkets in France are increasingly open on Sunday morning, even outside Paris. Some restaurants might be closed on Sunday evening but you should easily find alternatives.
Specialised shops might open, especially in the period leading up to Christmas but you cannot rely on all of them being open. In most places, they are only allowed to open on a limited number of Sundays but there are seven areas in Paris where shops are allowed to open every Sunday.
Museums and attractions will be open on Sunday, most of them close on Monday (many museums in Paris) or Tuesday (Le Louvres and a handful of other Parisian museums, national museums outside Paris).

Are Parisian shops open on Sundays?


So beginner with german

Question: I have began learning German recently, I am using YouTube videos and the Duolingo app, but I feel that this is not so effective so I would like to ask you if there are any free materials well structured which help me? I am interested also in making conversations; any recommendation for that?
Comment: Can you give an example for such a video? Generally I don't like videos to learn because you are forced into the video's speed instead of doing things in your personal speed. And because most videos are only clickbaits for commercial purposes, not to bring good content.
Comment: How could videos be a help to learn a language? Most videos need 5 minutes to explain a thing that textually would only require one phrase :-) Get a *good* beginners book. This is not free but imagine who should put effort into creating something worthy and then give it for free.
Comment: @puck thank you, don't you think that such videos are good for someone who just started? Could you recommande any books please? could you upvote my question because now i am restricted o comment others posts please ?
Comment: Possible duplicate of [What is a good way to start learning German?](https://german.stackexchange.com/questions/2040/what-is-a-good-way-to-start-learning-german)
Comment: I linked to a very similiar question already asked. If you look at the right column, you see the now 2 times downvoted question "Best way to learn German" (might change in futur). I opened it in a new tab, and from there was a link to the duplicate, I mentioned. While editing your question, there are suggestions of similiar questions. You are expected to check them yourself, to prevent you from writing q. which get closed.
Answer: Even if you like to watch videos, I recommend not to watch explicit those "language learning" videos. They are creating the illusion you are making progress, but in reality you aren't.

For learning the first steps of grammar, reading a beginner's grammar+textbook silently will help you concentrate on the sometimes complicated concepts much better than the overwhelming bells and whistles of a video.
For learning your first vocabulary, putting post-its with the German names of things (with their definite nominative singular article, please) on all the things in your household will help you much more. You will also learn adjectives and verbs that way. Seeing the nouns will make it a game to remember the right actions and supplements for them.
For getting in touch with the language, singing along to German music videos will get you much more experience how to intonate German correctly. (But not Rammstein et. al, please.)
For motivation, watching all-German (no subtitles either!) videos of topics you are interested in will make you want to understand that cursed dark elf language much more than any coursework you aren't really interested in.
Answer: Wikipedia in English is a good free start. It has well-structured grammar articles as well as articles about german phonetics, pronunciation, and even dialects. For practicing your language for free I would recommand Facebook and chatrooms. For asking questions, this is one of the best websites you can use. And don't forget Youtube!
Comment: Actually best thing is to hear a word. Not read about how to speak it. Facebook or other chats? Never! People don't write correctly there for all kinds of reasons. This is a place to get spoiled but not to learn.
Comment: Of course knowing phonetics is not bad. But you should hear the exceptions too. What I want to say with chats, there are so many wrongly written words, expressions and phrases. This is not colloquial language but more lazyness and sadly also stupidity. So if one presents "knowledge" from those chats in official life situations, I'd bet they appear more like an idiot than like someone wise :-) Nevertheless you are very right, reading or hearing audio is a very good idea. But please get something made with more effort. Else one could think "hey guuuys whazzuuuuup" is official english ;-)
Comment: The point of learning German is to finally be able to communicate with native speakers, so personally I think knowing about colloquial German is as essential as knowing about standard German although it comes later on. From my experience at least with English, reading a little bit about phonetics would save non-native speakers much time trying to figure out how things are pronounced correctly by themselves. It's simply like somebody else has done the hard job for them.
Comment: I totally agree that listening to authentic materials should go hand in hand with reading. In the same way using Facebook for the sake of practicing German should be accompanied by fully understanding that in there is mostly a non-standard language variety used, not to mention that FB has many groups and pages for learning German which would be helpful for beginners as well.

So beginner with german


Translated sentences of Kellerman's 'A complete grammar of Esperanto'

Question: At the end of lessons in Kellerman's 'A complete grammar of Esperanto' there are 'Sentences for Translation' exercises. Does anyone have a document with each lesson's translated sentences in Esperanto that I can use to verify my translations while practicing?
Comment: I found a link on Project Gutenberg, but no answers: https://www.gutenberg.org/ebooks/7787
Answer: I found the following partial solution set by Vaughn Seward: ANSWER KEY (PDF)
Unfortunately it only goes up to Lesson 17 (out of about 60).
I also found an online Hebrew version of the book which uses many of the same exercises, and includes solutions: HEBREW TRANSLATION
It contains all sixty lessons, but the sentences are differently numbered, and some are different altogether. I also noticed a typo or two.
Answer: Vaughn H. Seward wrote the incomplete answer key, but he did not trust himself, and so he let his work be reviewed, proofed, and annotated by Dan Campbell. I have tracked down a couple instances on the web of a Vaughn Seward who has cross-connections to Esperanto, and I believe that he is an older gentlemen with gray hair and gray facial hair, well trimmed, and he seems to be healthy. He wrote a note on the last page of his answer key, dated 05-27-2008, where he says that the answer key will be completed later. I have not been able to find an email address. I take exception to some of his answers in small parts, but the answer key is nonetheless helpful, and I would like to see it finished. I will continue looking for contact information for either or both Vaughn H. Seward and Dan Campbell. I was happy to see that this interested others as well. I think its a good book, and I am going to try to work through it daily to the end.
Answer: I happened to come across this discussion by accident. I'm pleased that there is still interest in the Kellerman book and the answer key that I had worked on back in 2007/2008. At the time, I was a beginner and, as you mentioned, I relied on more experienced members of our local club (namely Dan Campbell) to check the answers. I think it is a worthy effort to complete the answer key which I will add to my current task list.
I just checked, and I had actually completed up to chapter 47 out of the total of 60 chapters, so I'll need to finish the other 13. However, I'll need to first review and correct chapters 18-47 that wasn't part of what I had previously provided publicly.
Ray, can you provide the questions that you have some disagreemant, and perhaps can sort out what they should be.
Answer: Update (2023-04-23): I have updated the Kellerman answer key. It now includes answers for chapters up to chapter 38.
Answer: Update (2023-10-04): We have completed all 60 chapters of the Kellerman answer key, and have updated our website. We have also corrected a few things in the colour version of the Kellerman text.
http://esperanto-edmonton.wikidot.com/kellerman-answerkey
Comment: This is great and much appreciated, thank you for doing this.


Chanel Resistance in a saturated MOSFET

Question: In a MOSFET if VGS is kept constant then VDS is increased till entering a saturation mode, a pinch-off accrue near the drain. This indicates that the E field between the gate and the bulk is not evenly distributed due the increasing positive potential at and near the drain region. This phenomena will also affect the resistivity of the channel. Does this means that the resistivity near the drain have the highest value? If so the dissipated power is mostly generated near the drain?
Comment: Yes, I believe it does.
Answer: Interesting question.
I simulated for a year electronic semiconductor devices.

Channel resistivity is a 2D function: ρ(x,y).
ρ(x,y) changes as VDS change.

To answer your question:
Does this mean that the resistivity near the drain have the highest value?
Yes, it does.
Is the dissipated power mostly generated near the drain?
Yes, it is.

The external circuit will see the overall channel resistance R which is the 2D integral of ρ(x,y).
You increase the channel width W, you reduce R.
The electric field vector E(x,y) and the current density J(x,y) are 2D functions as well.
Comment: In a saturated FET, the depletion region between the drain and the channel (the pinch-off region) is not considered as a resistive region -- it is non-conductive -- but carriers are flowing in it (similar to injected carriers across the base-collector junction of a BJT).

This essentially is why the drain current DOESN'T increase with drain voltage -- that current is determined by what is generated by the source and channel at that end.

You are correct that most power is at the drain end. FET channel lengths are very small, and this heat spreads throughout the device quickly.
Comment: Thank you very much for your answer. That's what I thought. But what confused me was an answer to a similar question stating the opposite (lower pinch resistivity - https://electronics.stackexchange.com/questions/77198/why-mosfet-pinchoff-occurs). How someone can confirm this theory (by simulation or by measurement)? Is there any publication or a reference to explains it? Am I missing some quantum phenomenon here? A reference states that the velocity of electrons increases as they pass through the pinch-off region to the drain.
Comment: If we further increase VDS, the Pinch-off becomes more severe, but the current remains constant, and according to the following relation Pd should increases (Pd = (VDS ^ 2) / Ron), till the channel fail (at the site with the highest resistivity).
Comment: Michael: all devices simulators solve the so called "Drift-diffusion equations" starting from the boundary and initial conditions and from semiconductor data. In this context E(x,y) and J(x,y) are the unknowns. Once the simulator has finished (usually after 12 hours or more) you can evaluate current I at a certain section, plot or evaluate resistivity etc. If you change VDS, you have to run another simulation. The pinch-off condition or inversion condition can be seen after the simulation has ended.
Comment: Back in 1995, devices simulators like IBM's DAMOCLES, did not use quantum equations. They solved the drift-diffusion equations.

Chanel Resistance in a saturated MOSFET


How to decode an Ethereum transaction input of an 0x transaction

Question: The input data is very large. I believe there are multiple functions called.
Can I just hash each of the functions in the ABI, get the 6 characters and compare them to the first six characters of the data. Then get the inputs and match them to the next characters in the data. Then just remove the matched characters and start the process all over again to find the next function and parameters?
Do I need to transform the input data at all? I haven't had much success with the mentioned process yet, so I assumed maybe I am missing something there.
Another issue is that the 0x contract has multiple different ABIs. Can I just combine them into one array if there are no conflicting functions names? Or even if I know the functions needed just keep those in a created ABI?
Also I want to do this in PHP, I have found other libraries in JS and python that I can't use for this project but can use for reference. I need some help with these questions to help move me forward.
Answer: I was able to get the combined ABI from etherescan. different sol files did not mean different ABIs.
There also is and can only be one function call. The other data I was looking for were in the event logs.


Is it possible to control a 12v led matrix with an arduino?

Question: This is a bit home automation but if I want to control my 12v LEDs and I have 8 free pins would it be possible to drive 16 lights as a matrix. I was looking into running 8 LEDs with an 8 channel relay but the I got to thinking if I wire up 16 LEDs in a matrix I could still control them all with those 8 channels. Problem is I was looking at mechanical relays that would burn out very quickly with that kind of switching. Are there any other solutions?
Comment: @frarugi87 Yes, thanks again, I decided 120vac would be many more problems than it's worth and I have a main priority of not burning the house down :)
Comment: Why mechanical relays? since they are 12V leds you will need 12 MOS (4 nMOS on the columns, 4 pMOS on the rows and 4 more nMOS to pull the pMOS gate to ground (since your arduino can output at most 5V). they are much cheaper than relays, much smaller, much faster and will last much longer...
Comment: I originally found the relays that we rated for ac and DC and it seemed nice to have the option.I started looking into solid state relays but couldn't find a balance between price, quality, and available datasheets. I'm way more of a software guy so that explains why transistors slipped my mind
Comment: If you want AC support then you'll definitely need to wire them one by one, or you'll maybe get some weird behavior. As for relays, you will not be able to use them in a matrix. The reason, apart from the wearing, is that a common relay needs 10-20ms to switch, and you will need at least 200 flashes per second (but more is much better) to get an acceptable light. I mean, if you turn on an led for 10ms and then off for 30ms (100Hz switching frequency) your light will blink at 25Hz, and your eye will see the light "flashing", which is really tiring for the eyes. So.. Just go with transistors ;)
Comment: @JacobKern How's your project going? Did the answer lead to a solution?
Answer: You can use ULN2803 driver IC on sink side (cathode), P channel MOSFET on anode/source side of common anode LED matrix. Since you need only 4 sinks you can pair every 2 i/o of ULN2803 so you can drive/sink 1A max load per row. This IC is cheap and widely available.
MOSFET current and speed should match those of ULN2803. You can use BJT instead of MOSFET, but voltage drop on BJT will be higher.
Similar design is here: 8x8 LED matrix
Comment: The real gem is your similar design. It shows two daisy-chained shift registers. So with the 4 pins, you can drive the two shift registers, who drive the P-channel and ULN2803. Effectively 8x8 with only 4 inputs and it's even very scaleable.
Answer: I think the best solution would be to use WS2812 LEDS. I already implemented this many times also for my home illumination.
WS2812 is a RGB LED with an integrated chip (1m strip with 60 LED will cost about 10$).
One advantage is that you need only 1 output from your Arduino and the library works very well.
Another one is that you don't need power! 5mA is enough to drive 1000 LEDS! So you don't need MOSFETS and you don't need any Relais.
Comment: I would choose an SPI based digital ledstrip. They're easier to control with various devices and leave soms time inbetween setting pixels to be able to calculatie the next one. Which is much more memory efficiënt.


How to list the second edition of a book

Question: If an author has published a second edition of a book and he is in his earlier career stage as a mathematician, how do you recommend to include this second edition into the list of publications appearing e.g. in the CV? For example, should it be mentioned at all? Should it replace the first edition? Should both editions be listed, in particular when the second edition is a massive revision and 20 pages longer?
Comment: I can't imagine there's any rules about this, but presumably if someone reading your CV were to see a book listed amongst your publications which was marked as the second edition, they would assume you had been involved in the first edition as well. Listing multiple editions of the same book could also give the impression that you're trying to pad out your CV.
Comment: @NateEldredge That's true. As I was writing that I did think of several multi-edition textbooks whose original authors have long-since surrendered the reigns. Perhaps a sensible default would be to only list the most recent edition you were involved with, and include a note if you weren't involved in one or more preceding edition.
Comment: @Ian_Fin: I agree that typically one should only list the most recent edition.  But it does sometimes happen that, say, Author A wrote the first edition by herself, and then Author B joins the project to work on the second edition.  So B was involved in the second edition but not the first.  Sometimes this happens for textbooks that continue to be revised long after the original author has retired or died.
Answer: Normally you would just give the bibliographic information for the most recent edition.  If you feel it's important to say when you first wrote it, you could add a parenthetical like (First edition published in 1987).
If the book was originally written by someone else, and you joined as a co-author on a later edition, then include a note like (Co-author for editions 5 and later).
This would be the same regardless of what stage of your career you are at, and as far as I know it would be the same in any field.


How many translations of "ichigo" are there?

Question: "Ichigo" can be the pronunciation of a person's name (as in the cartoon "Bleach"), or words meaning "strawberry", "one and five", or a part of the word "一期一会". Are there any additional meanings of "ichigo"? Are these words homonyms or do they have different tones?
Comment: How many "translations" or how many "meanings"? If you start thinking about translations, the number would depend on the destination language(s). `苺` can be "strawberry", "fragaria", ..., `一` can be "one", "uno", "yi", ..., .
Comment: Related: [Can I write Japanese name "Midori" this way - 緑?](http://japanese.stackexchange.com/q/2553/542)
Answer: We have three words in everyday vocabulary according to dictionaries.

苺 strawberry (pitch accent in Tokyo dialect: Low-High-High)
一語 one word (LHL)
一期 a whole life (usually used in the compound word 一期一会 LHH-L(H)HH?)

Also we have:

一五 one, five (when reading aloud the numbers separately).

参考 http://accent.u-biq.org/i.html
Answer: It's mainly down to the myriad readings of the kanji that are available. For instance Ichigo (the name you reference) may not use the same kanji as 一五 (one, five)
Note: I'm not a fan of Bleach, so I wouldn't know if Ichigo was spelt in kanji or kana.
Using my dictionary, I'll pull out 5 random kanji that can be read as Ichi or Go
Ichi can be any of these kanji (took the first 5 kanji only):

一
位置
市
壱
居ち

Go can be any of these kanji (took the first 5 kanji only):

語
後
五
御
誤
伍

Obviously, the combinations of Ichi and Go will be quite small, but since you didn't specify whether you wanted a list of the possible combinations or just all of the different readings for these characters.
Obviously the list of combinations of these characters that make up meaningful names will be even shorter. But you have to remember that not every Japanese person's name is made with kanji only. Some people (I've met several like this) have kana only given names. Again, you didn't specify whether you wanted just names (either given or family) that could be spelt, in romaji, with the characters "ichigo"
The thing with asking these types of questions, in my opinion, is that there are hundreds of ways to convert a romaji word into something from a Japanese dictionary.
These, obviously don't include the kana readings of ichi (いち and イチ) and go (ご and ゴ)
Someone with a higher level of knowledge will be able to provide you with a better and more detailed answer. I don't wish for this post/answer to come across as pedantic, so I apologise if that is how it came across.
Comment: What is 居ち (in modern Japanese)?
Comment: Must "ichigo" be written by one of the  combinations of kanji listed there? For example, can someone simply say that "陽" is read as "ichigo" ?
Comment: These where all examples. They might not make sense, I was just pointing out that if you ask "how many ways are there to write this Japanese word (in romaji characters) in Japanese script?" that there are going to be lots of different combinations.


Replace Bones with existing bones from other models | 1 animation for 2 differnt models

Question: i think there is a easy way to fix but i cant find it(Beginner).
So i have two different models; 1 Character and 1 weapon both of them have their own pose/bones but I can see that the bones/pose from the weapon are similar too the bones from the character. Now i want to use an  animation of both together but it will only apply to one of the models, not both. How can I fix it?
Answer: Select the armature that doesn't have the animation, create a dope sheet window, turn it to an action editor, select your animation in the drop down menu.


Does distance to nearest IXP affect download speeds?

Question: Out of my element here, but...imagine one person lives 100 miles away from the nearest internet exchange point, while another person lives 200 miles away, would there be a measurable difference on internet speed?
Answer: When you say "speed," I assume you really mean "throughput" (Here's the difference).
If we assume the same bandwidth connection to the IXP (e.g., both have a 1 gigabit connection), and the same network conditions (link utilization, error rates, etc), then then the throughput will be the same.
Because of the longer distance, the first bit will arrive faster to the person 100 miles away than the other one at 200 miles.  Given the propagation of light/electricity through fiber or copper, the funny cat video will start about one millisecond sooner for the first person, but it will play at the same rate.
Comment: Internet Exchange Point https://en.wikipedia.org/wiki/Internet_exchange_point  I suppose practically speaking, users don't connect to IXPs, but the result is the same.
Comment: Wait, what does the "X" stand for? I was expecting someone to comment "you mean ISP - Internet Service Provider".
Answer: Practically, you would not be able to perceive a 100 mile difference as the transmission times are near the speed of light (186,000 mi/sec).  Technically, there is a difference in transmission time though.


I have a mail server that hosts several client emails but 1 in particular is being blocked because of its SBRS score

Question: If I was hosting emails for 3 clients and my reverse DNS is mail.allclients.com and I am hosting for client2.com, client3.com etc. What would be the rDNS for client3.com? Would it reflect the rDNS of mail.allclients.com? If so, I do I prevent mails from client3.com from being blocked because the PTR does not match rDNS?
Finally on your advice to have my email service publish an SPF record. Is this something I need to submit to the company I registered my mail.allclients.com to? So I for example registered with GoDaddy.com then I will need to submit a request to them to publish an SPF record on their DNS right?
Thank you for your advice and kind assistance.
Vince Saavedra
Answer: Reverse DNS is based on the IP address.  You can have many forward DNS names resolve to one IP address, but that one IP address should only reverse to one DNS name.
Most email real-time black lists are also based on IP address.  If your IP address is black-listed or has a poor reputation, you will need to make sure no spam is being sent through your server and contact the individual list maintainers for help getting de-listed.  Since you are hosting for clients, you will need to instruct those clients carefully on what is Acceptable Use and act quickly to block anyone violating that.
Adding an SPF record to your DNS record does not hurt, provided you keep it up to date.  It is good practice to have an SPF record, but mostly because it slightly reduces the ability of other people to impersonate your server.  It does little or nothing to improve your own server's perceived reliability.  Whoever is maintaining your DNS would need to create the SPF record.


solving a hyperbolic set of equations - upwind type method

Question: I want to solve a set of hyperbolic equations (not the Euler equations) using an upwind type method. I am interested in using a first order upwind scheme and one that is not based on the method of characteristic and does not require the eigenvalues and eigenvector. So far, I have understood that I first need to solve the Reimann problem, to find out the wave speeds (If I'm not mistaken) and then use that information to work out the fluxes at the boundaries using Gudnov type methods. I was wondering if someone could give me a better step to step guide of what I need to do, and recommendation on the type of methods to use?
Comment: Please edit your question with the following information: is the problem linear or nonlinear?  If it is nonlinear, do you expect shocks to appear in the solution?  If so, do you know the physically appropriate jump conditions?
Comment: Why don't you want to look at the method of characteristics?
Answer: If you like using the finite element method you can use the streamline upwind Petrov/Galerkin (SUPG) which is essentially a stabilized Galerkin method.
Similar modifications can also be made to FDM and FVM.


Harvesting transaction fees

Question: So let's assume I don't care about energy consumption and mining the famous reward for discovered block. Is it possible to set up a workstation optimized to harvest just the transaction fees? Do I need to participate in a pool and run mining software?
Answer: No, it doesn't work like that.  The fee for a transaction can only be collected by a miner who creates a block including the transaction.  Creating a block also entitles a miner to collect the "famous" block reward (they could decline to collect it, but that would be stupid).  There is no easier way to collect transaction fees; you have to mine like any other miner (either solo or in a pool), and at least for Bitcoin, you can't economically do that with ordinary computer workstations.
Comment: I think you can safely remove the word 'economically' these days.
Comment: Thanks. This is a big problem for any financial institution who want to enter the business of payment processing... I guess there's no such business in bit coin
Comment: @francesco: Indeed, there's no such business. There isn't any other "processing" that Bitcoin payments need.
Comment: @NateEldredge thanks! It's more clear now. I just wonder what will happen the day mining will not be profitable anymore... Who will process transactions?
Comment: @francesco: This has been covered in previous questions on this site. Different miners have different costs depending on the hardware they use, the price they pay for electricity, their overhead, etc, so it won't become unprofitable for everyone at once. As it becomes less profitable, miners drop out, mining difficulty drops, and profitability increases again. So in principle equilibrium is maintained.

Harvesting transaction fees


What is the difference between a knuckle and spindle?

Question: Surprised I didn't see this asked before but when watching videos about suspension components and installs I've commonly seen people refer to, what I would imagine a spindle, but call it a knuckle.  So what is the difference between a spindle and a knuckle or are they both the same?
Answer: The knuckle is the part the spindle attaches to. The spindle carries the hub and bearing(s). Generally the spindle is used on non-driven wheels, but there are some where the spindle is hollow and the CV shaft extends through e.g. Some Nissan's. The bearing(s) and hub assembly are still on the spindle, there will be a drive flange that bolts to the hub.
A spindle attached to a knuckle.

A knuckle for a bolt in hub and bearing setup.

The term seems to be used interchangeably though.
Comment: Sorry to be pedantic, but knuckles with spindles can absolutely be used on wheels that are driven. On the front wheels of my 2001 QX4 I have a knuckle with a spindle very similar to the first picture you have, except the spindle is a bit thicker and is hollow where the CV shaft rotates inside.
Comment: @atraudes Indeed it does, I forgot about truck setups when answering. The Pathfinder uses a similar setup as well.


Spacecraft electronics heating

Question: As much as I know of integrated circuits is that military components have lowest temperature working limit - I think -40 deg Celsius. Having in mind that temperatures in open space are less than -200, I come to conclusion that electronics inside spacecraft need heating. Although spacecraft devices spent much time in sleep mode, some electronic circuits must be alive (at least real time clock and few devices that should wake up the rest when needed), by my opinion.
I wonder if this way of thinking is OK or maybe there exist some special kind of components regarding severe temperature conditions ? If heating is needed, does it mean that entire interior of spacecraft should be heated (when not sleep) or just few it's separated regions ? In that case I'm really surprised how generator's energy is conserved, having in mind heating and external temperature values, but maybe I missed some important issues.
Comment: Information on how New Horizons does this: http://space.stackexchange.com/questions/9902/what-powers-new-horizons
Comment: @Zoran also see the *excellent answers* to [WHY did Rosetta have to go into hibernation for 2.5 years?](https://space.stackexchange.com/q/15374/12102) and also [Is this the longest that a spacecraft "went to sleep" and then woke up on schedule?](https://space.stackexchange.com/q/15371/12102) as well as the ESA video [How Rosetta wakes up from deep space hibernation](https://youtu.be/UqcDtRmJbKY).
Answer: Space is really cold, that is true. However, how does that temperature get to the spacecraft? There are 3 means of transferring heat, namely:

Conduction (Direct contact)
Convection (Contact through air, water, or some other liquid medium)
Radiation (Radio waves emitted based on the temperature. See Planck's Law)

Of these, in space the only one that matters is the latter. The spacecraft heats up by the rays of the sun, and cools off by large areas that aren't seeing sunlight. Okay, so what does that mean for a spacecraft?
Most spacecraft have electronics that generate heat. Some items do very well with little heat, others are more specialized. For instance, most radios have an Oven Controlled Oscillator (OCXO) that is heated to a precise temperature. Batteries usually have a modest range where they work best. Other electronics might be more forgiving. Propellant is often very sensitive as well.
One of the highest powered devices is usually the radio. These will heat up quite quickly, while other components require heat.
For spacecraft further from the Sun, there is less heating from the sun. A combination of insulation, helps, although the biggest advantage is using the heat from the RTG, which will also help heat the spacecraft, even passively.
The bottom line is, most spacecraft do have a few heaters on specific item, but only heat what needs to be heated, and don't heat what doesn't need to be heated. It's actually quite possible to get a spacecraft that doesn't need any heating around Earth, if it can be maintained in the same environment (Same eclipse periods, for instance) Usually the heat is designed to work best in the hottest environment, and the spacecraft warms itself up otherwise, because it's easier to heat something up than cool it down.
Comment: The solar power isn't ever completely negligible, but the same thing applies. Deep space probes actually have a ready made heat source, the RTG, which helps them maintain heat.
Comment: I was not precise, but my point of interest are of deep space probes, like Voyagers or so- where Sun energy is negligible. Anyhow, thanks for revealing me few details I didn't know.

Spacecraft electronics heating


Where to get experience in performing?

Question: I understand this is kind of a vague question since it varies depending on where you live, but what are some common places that most cities have that let amateurs perform live? I'm really a shy type of person (at one point I was to embarrassed to play/practice in front of my parents) so I figured if I were to perform now it would be very stellar and mediocre but if I try get outside my comfort zone as much as possible by performing a lot I might be able to give a good performance. I would like to start out not performing solo because I think that is way too intimidating for me. If it helps I play the guitar and I would be interested in hearing how the more experienced people out there started out performing live.
Comment: Karaoke helped me a lot, but you basically have to just get out there and get on stage.
Comment: There is a similar question on Music SE with some excellent answers here (http://music.stackexchange.com/q/31045/16897)
Answer: It's going to be dependent on the sort of music you are playing, to a great degree.
You may join a vocalist, and simply provide a rhythm guitar backing. You may become a member of a band, perhaps 4 or 5 of you, where the spotlight won't be on you much. You may want to try a bit of busking, with others, where the public will be passing, and therefore the audience is changing by the minute. You may want to join a local church, where you could provide some guitar music for some choir songs, of for the congregation to leave, listening to you. You could advertise for others, or to join others, on sites such as 'Join My Band', when the auditions and rehearsals themselves will help you. You may like to record some stuff to play over - loop stations are great for that - so you won't be 'playing alone' in a manner of speaking. You may want to go along to an open mic night - others such as you will do the same - and play with those others. You might like to try a local youth club or music school, which have mini gigs. The list goes on... and on.
Comment: Highly recommend open mikes, usually the audience is made up of people who understand exactly what you are going through.
Answer: If you want a chance to play with others in front of an audience, your best bet is open jam sessions. Like open mics, these happen at cafes and bars. They're not as common as open mics, but there are still plenty, especially in the big cities. Blues, bluegrass and Celtic music all seem to have a lot of open jams. There's a decent amount of them listed on Meetup.com, and I'm sure there are other sites I don't know about. These have the big advantage that there's a zillion other players there, so if you mess up, people will hardly notice.
If you just want to get comfortable playing with others, but don't need an audience, there are also loads of private jam sessions. Many of these are only "private" in the sense that they happen at somebody's house with no audience, but they still welcome new musicians. Again, a lot of these can be found on Meetup.
You can also just ask some of the musicians you do know about the jam situation in your city. Word gets around pretty well.
Comment: "if you mess up, people will hardly notice."  Also, you can probably just show up and listen at first and take note of the songs they usually play and go home and learn them.
Comment: Also, you might want to just try going to an open mic and see if you can get up the nerve to get up there. The thing is, most players at open mics are _terrible_. It's really hard to be the worst player at an open mic. No matter how bad you butcher it, you're still going to be better than the strung out hippie who did a 10 minute free jazz version of "Friend of the Devil" on an out-of-tune acoustic.
Answer: There is only one choice: in performances. But note, that you don't have to be the soloist, or even play everything, the event may even have a different main focus (like a photo presentation), where you just musically introduce the break.
If this fails, the next best choice in my opinion is chamber music; you will have no other audience than your co-musicians, but this is at least a big step compared to playing for yourself.
Answer: Google for your city and "open mic" or "jam".  Spectators are usually welcome, so you can go without your instrument at first to get a feeling for it.  That's also a way to meet people that might be fun to play with.
Answer: That is an excellent question and I can relate to what you are feeling.  When I first started learning to play guitar and sing I got to a point where I was perfectly comfortable home alone on my couch singing and playing for the furniture.  But bring an audience of even one person in the room and all of a sudden I couldn't get my fingers to work and could not even play a basic chord!  I think they call it "stage fright" - and it's normal for most humans.
Eventually if it does not kill you, it will disappear and you will relish every opportunity to perform for others (live) - once you gain confidence.
If you want to start slow and work your way up to live performances such as  open mics and open jams others have suggested - here are some ideas that I used to slowly overcome the fear of an audience.
One thing to try is simply playing outside on your front porch or back deck or sitting on a park bench where you don't actually have an audience in front of you - but the mere possibility that someone might hear you will provide a very tangible element of fear that it will take a deliberate effort to overcome.  I can remember when I first did this on the back deck of a condo I lived in.  I couldn't see anyone so I could easily pretend that no one was listening.  But still I could feel the intimidation factor kick in when I moved from the safety of the couch to the back deck.  One time after a performance I could actually hear several unseen neighbors applauding.  That actually made it more like performing for a real audience going forward - but eventually I became comfortable playing for my unseen audience and the applause became a regular reward.
Another idea that will help you get used to dealing with the "stage fright" is recording your performance.  In the recording studio they call it "red light fever" and it's a close cousin of stage fright. New recording artist experience it the first few times in the studio - where they perform a song flawlessly when the engineer is just trying to tweak his levels but when the actual recording process starts - they fall apart (happend to me my first time).
You can set up a video camera or smart phone on a tripod and make a video of your performance.  At first you will see that hitting the record button will cause you to mess up more than if you were not recording.  Eventually you get to a point where it does not affect you.  Knowing you can delete the video before anyone sees it reduces the stage fright to a tolerable level.  Once you can pull off a video recording of a performance you would not mind sharing with others - then you are ready for the next step.
Post your performance on YouTube.  Set up a YouTube channel for your musical performances and set a goal to post a vid of your performance of a song you have mastered.  Then another, then another etc.  Knowing that the world will be watching will provide a greater intimidation factor to conquer- but knowing that you don't have to post the outtakes will reduce the pressure.  You might want to disable comments when you post - because the intraweb community can be quite critical and quite harsh.  You don't want negative comments impinging on your confidence quite yet.
Invite a friend over to hear you perform.  At first you will find this very intimidating.  But if you have already posted a performance on YouTube and you think it represents a good example of your current skill level, invite your friend to view the video before seeing you live.  Then you will overcome that first hurdle - the fear of being judged - because they will have already had the opportunity to judge you by watching the video and you will feel like you have already proved your ability before the live performance.
Perhaps even tell your friend what you are hoping to accomplish and say - "I was able to overcome the fear of recording my performance and now I want to see if I can do the same for a live audience".  Then just keep playing the same song until you get through it at the same level you know you are capable of when alone.
Once you can comfortably play for one friend, throw a party and invite several friends.
Optional if you have the time and money - Take private or group lessons.  You will be performing for your instructor and if in a group lesson, in front of other budding guitarist who will likely be going through the same feelings you are - which will make it easier for you.  Guitar Center in the US sometimes hosts free guitar workshops for beginners.  Even if you are not a beginner, one of these type workshops will give you some experience playing for others.
Another idea is to go to your local guitar retailer and try out some guitars by playing some songs you know.  I found this less intimidating than playing a full song for a friend when I was a newbie.  I didn't feel any pressure to play any song perfectly because after all - I was just trying out the guitar.
Open jams either organized or informal are a great way to play along without being the center of attention.  At an open jam you can just strum along with a bunch of other musicians and pretend nobody is listening to your guitar.  If you get lost and drop out, the other guitarist playing along will carry the song forward so no worries.
When you have developed the ability to perform for a small group of friends, you are probably ready to try your first open mic (although you will never actually feel like you are ready).   You might tell the host or hostess that this is your first ever open mic and you only want to perform one song - or two if you feel comfortable enough after the first (or feel a need to redeem yourself).  Before the big day - pick a few songs that you are most comfortable playing and practice those few songs until you can perform them flawlessly without thinking about them.  No complex chords or fast changes or complicated strumming patterns.  Then get up there and do it!
Tell yourself that your goal is just to survive your first open mic.  You can announce from the stage that this is your first open mic to lower expectations if it makes you feel more comfortable.  The audience, consisting of mostly other musicians, will be sympathetic and supportive because they can probably remember how scary it was at their first open mic performance.
The first open mic is always the hardest and scariest by far.  The second time you perform on stage at an open mic will be exponentially easier than the first time.  It's like jumping off the high dive for the first time.  Once you overcome the initial fear of doing it and realize that you didn't die and that it was actually kinda fun - you can't wait to do it again.
It's a journey - but if you take it one step at a time you will soon be posting YouTube vids every other week and making Open Mics a regular part of your weekly routine.  Before long other musicians will be inviting you to join their band and next thing you know you will be getting paid to perform on stage.
Good luck and enjoy the journey!
Comment: "Practice a few songs." Probably the worst thing one can do is get on stage without properly practicing. And practice doesn't mean an afternoon. Make a set list, and practice the changes, a lot. If you get up without practice and miff the whole thing (multiply average miffs by number of band members), you wind up with a really horrible personal experience.
Comment: @Yorik  Totally agree.  By practice a few songs I mean pick a few songs you can play well and practice until they are what I call stage ready.  Meaning you can play them in your sleep.  You will still mess up but the more you practice, the more confidence you will have and the fewer mistakes you will make.  For first open mic/live performance you want to focus on a few songs you can play well as opposed to attempting to learn an entire set list since most open mic slots are 15 minutes long and can be shorter.  By focusing on a few songs vs a bunch of songs - you can really get those down.
Answer: Busking is a great way to gain experience and gain real-time feedback on your performance.  Passersby will vote with their attention and their money.
Or as Woody Guthrie put it (paraphrased):

Find a place, put your hat down in front of you and start playing. When people start putting money in the hat, you're a professional musician.

Where to get experience in performing?


Can I list my experience as independent researcher to my resume or CV?

Question: I have graduated from my master's last year. I am very much interested in doing an additional technical master's program and/or a Ph.D. in my field. So, I started applying for both the technical master's program and for the PhD program. In the meantime, I thought of not letting my research interest decay, I started working as an independent researcher. And luckily I got a collaboration offer from a foreign university professor who was a great scholar in my field of study. I collaborated with him from my home and did nearly 8 research articles within a period of 11 months. But at the same time, I was rejected by all the M.sc. and Ph.D. programs I applied. However, my independent research works were accepted and published in reputed IF international journals. Now, I am applying for the winter semester programs, in that case, can I please know whether I can add my experience as an independent researcher to my resume or Cv which I submit to the educational institutions? Please kindly help me in this regard. Thank you in advance.
Comment: Unfortunately, "independent researcher" can mean a wide spectrum of things, anything from doing serious research published in good journals (as you've done) to sitting around thinking "deep" thoughts that never lead anywhere (and might not even make sense). The important thing for your CV is to emphasize the publications that show you're at the serious end of the spectrum. The phrase "independent researcher" can fill what would otherwise look like a gap in your history, but the publications (and, as Buffy pointed out, letters of recommendation) are the real information.
Comment: Thank you very much for your comments, sir, Buffy, and Blass, I will add it in my CV, I already have a recommendation letter from the professor and since my articles are accepted to Elsevier publication above a IF of 4, I think as per your suggestions, I will add it. Once again thanks for your comment.
Answer: Yes, absolutely add it, along with the publications that resulted. And, you should consider getting a letter of recommendation from the professor. Your lack of formal affiliation is of no consequence. It is the work that matters.
Don't hesitate here.


Column calculated value to get the current date time?

Question: I have tried using =TEXT(Today,"mm-dd-yyyy hh:mm:ss") but that only returns the 5/5/55 00:00:00, it won't give the time. How do I get both the date and time with a calculated formula?
Comment: I think he did ask a good specific question. " How do I get both the date and time with a calculated formula?" The issue is that time is always 00:00:00.000.
Comment: Why don't you edit your question and put down what you're trying to acheive with this, e.g. "Display red text when a task is overdue". Today in calc columns doesn't work but there are other ways to do things - so tell us what you're trying to do.
Comment: Check [The supported and unsupported fields in SharePoint calculated column formula](https://blog.devoworx.net/2017/09/11/supported-fields-in-calculated-column-sharepoint/)
Answer: Unfortunately if you are trying to have this always show the current date and time, this won't work since Calculated Columns are not recalculated on viewing, but only on creation and modification. See this article: http://blog.pentalogic.net/2008/11/truth-about-using-today-in-calculated-columns/
However, if you are just trying to extract the time when calculated then you could switch your formula to: =TEXT([Modified],"mm-dd-yyyy hh:mm:ss")
Comment: [Today] doesn't work, never has, even with the fake today column tricks. You said so in your question - now you're saying it does. Want to clarify?
Comment: I have tried this, but it seems the [Modified] part of the formula is not working and every time I try to save the changes to the column I get a runtime error, however [Today] will work. Does the column with this formula have to be set to a certain type or will Single line of text work?
Comment: The `=TEXT([Modified],"mm-dd-yyyy hh:mm:ss")` formula doesn't work if you switch a regular text field column to start using a calculated formula. For example we had a text field that got used for a bit and now the end-user wants it to generate a random number. My first instinct was to flip the radio button to "Default Value: Calculated Value" and put that formula in. This does not work because the Modified column hasn't actually been populated yet.

Is there a way to get an accurate timestamp without being forced to do so within a calculated formula column specifically?
Comment: What if list is created and modified column is created . In my case , the above formula giving run time error although the list is created .
Answer: you can also Use Now() instead of Today()
=TEXT(Now(),"mm-dd-yyyy hh:mm")

a sample for date diff
=IF(NOW()<=[End Date],
DATEDIF(NOW(),[End Date],"d"),
DATEDIF([End Date],NOW() ,"d") * -1)

Answer: Sure you can, here are the methods
http://office.microsoft.com/en-us/windows-sharepoint-services-help/CH010103260.aspx
Comment: Yes there are formula to extract date/time from a date field BUT [Today] does not work in calculated columns.
Comment: That is true, you have to build it for yourself
Answer: I have a list with tasks that all have to be finished within a certain deadline. I wanted the list to show me which deadlines were getting closer or were exceeded. After a long search on the internet I found there was no satisfying solution to make a column using the current date.
However, I found out that when you modify the view of a list, you can put [today] in the filter section. This allows you to base the view of your list on the current date. This date will automatically be kept current. (I have a Dutch version of SharePoint, so I hope I guessed the used terms right ;) ).
I made 3 different views of the same list on one page. For all views I edited the list view and checked the box which says only show items if under the tab filter ;
View 1, named: Deadline exceeded:
'Only show if'

'deadline' column

'smaller than'

[today]

View 2, named: Deadline < 30 days:
'Only show if'

'deadline' column

'bigger than'

[Today]

and

'Only show if'

'deadline' column

'smaller than'

[Today]+30

View 3, named: Deadline > 30 days:
'Only show if'

'deadline' column

'bigger than'

[Today]+30

Additionally I placed the different webparts in colored tables (red, orange and green).In this way it's very easy for me to prioritize the different tasks in my task list. .
Answer: The formula to add for only the date is =TEXT(TODAY(),"mm/dd/yyyy"). Make sure the outcome is a single line text.
Comment: The question is how to get date and time, not only date..


Does Diffusion Sliver protect from boardwipe spells and sacrifice spells?

Question: If I have a Diffusion Sliver out, are my Slivers protected from Wrath of God? What about Chainer's Edict?
Comment: Although the question is different, [this answer](http://boardgames.stackexchange.com/questions/32951/does-heroic-trigger-on-a-static-effect/32952#32952) applies here, too.
Comment: http://boardgames.stackexchange.com/questions/4638/does-wrath-of-god-really-destroy-creatures-with-shroud http://boardgames.stackexchange.com/questions/14218/do-permanents-controlled-by-a-player-with-hexproof-also-have-hexproof
Answer: No, they are not protected
Diffusion Sliver's ability is only triggered when a Sliver becomes a 'target'. A creature is only targeted by spells or abilities that actually have the word 'target' on it. For instance, Giant Growth. From the Comprehensive rules:

114.1a An instant or sorcery spell is targeted if its spell ability identifies something it will affect by using the phrase "target [something],"

(Note that rule 114 in its entirety describes 'targeting', this is just a specific excerpt for instants and sorceries.)
The Sliver needs to be identified as that 'target [something]' in order for this specific ability to trigger. On instants and sorceries, this is spelled out; casting an Aura (ie Unholy Strength) on a Sliver also triggers the ability added to it by Diffusion Sliver, as they have an implicit target:

114.1b Aura spells are always targeted.

Casting an equipment would not trigger the ability, as they enter play unattached and not targeting anything.  Their equip-ability however would count as becoming a target.
To look a little closer at what spells do and do not target the Slivers:

Twiddle would target the Sliver and trigger this ability.
Turnabout wouldn't, because the card doesn't target a creature, it targets a player.
Call to Glory would not target the Sliver, as it doesn't target anything.
Answer: No, the key word here is "target". Your slivers get an ability that triggers whenevery a spell or ability gets cast/activated that contains the word "target", e.g. Doom Blade. Any spells/abilities which do not "target" your slivers are uneffected by diffusion sliver, as here in your example edicts don't target your creatures but you and wrath doesn't target at all.


Water under tile shower floor

Question: The calking around the shower (where the floor meets the wall) was loose and water has been leaking through it.  In removing the old calking I discovered that there is a build up on water visable.   In fact it's level with the tile.  Is there anyway to remove the water without tearing up the floor, which I can't afford?
Comment: Is this **inside** the shower enclosure?
Comment: Can you slide under some absorbent pads?
Answer: Vacuum it out, preferably with a Wet-Dry or Shop Vacuum that has a thin nozzle attachment applied parallel with the seam or a floor sealing Water Pickup attachment applied perpendicular to the seam. To assist this operation you can tape the seam so the vacuum's seal is concentrated. A bag-less vacuum can work just as well, but be careful not to fill it more than 1/3rd & damage the vacuum or electrocute yourself.
If those don't get most of it or neither are available to you then a thin towel or cloth, like bed sheets or clothing can be stuffed into the seam with a putty or butter knife to soak up & wring out until dry or mostly dry. Avoid paper towels as they can easily rip & are a pain to straighten back out repeatedly.
Then, let it air dry. If you need to use the shower then just duct tape the seam to keep water out for one. But for another, to see if the water is coming from somewhere else & the seam is filling up again. If it's unchanged then keep taping & un-taping until it's bone dry.
Finally, actually fill-fill the seam with caulk & force the caulk in with your finger. Don't bother trying to get it perfect the first time, instead come back in a couple of hours & do a second application of caulk to get the caulk flush to both the floor & wall. Then, don't use the shower for at least 6-hours. If you can't wait that long or longer then tape OVER, as in bridge, but don't tape ON the caulk.

Water under tile shower floor


Need help with a particle system

Question: I'm working on a basic animation, and am having trouble getting the effect I want from a particle system. I have a cube inside the torch object giving off "smoke" particles, that's parented to the torches' motion, and I want there to be a particle every few seconds that slowly rises straight up. I tried turning down the emission number, and turned off the gravity, but the particle always starts behind the back of the torch, and then moves ahead of it while going up. How can I get it to start from the cube inside the top of the torch, and not move while the cube moves?

 (With @eromod's answer)
Comment: can you include your .blend file? http://blend-exchange.giantcowfilms.com/
Answer:
Make a wind forcefield.
Make a particle system that isnt effected by gravity, has no starting velocity, and has some brownian motion.

I think you are asking how to have the particles only come from the top of the torch with no particles coming from the bottom? Just weight paint it and remove/re-enable it in the particle system so that it updates
Comment: I have to put effort in my answer? thanks for the reminder.
Comment: Link only answers are discouraged here. Please go into a little more detail about how to set it up properly
Comment: While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference.  Link-only answers can become invalid if the linked page changes. - [From Review](/review/low-quality-posts/33615)
Comment: The particles are moving really weirdly. I'll attach my .blend file in my original post

Need help with a particle system


Automatic lock not working

Question: 2001 Honda CRV, when lock button is pressed rear PS door lock sounds like a machine gun (ra-ta-ta-tat) and door remains unlocked. Door cannot be manually locked either, what could be causing this?  Is it likely to be the actuator gone bad, or just a mechanical jam up?
Answer: If you cannot manually lock the door, the power locks will not work because all it does is move the mechanical linkage. This sounds like the linkage or latch (the lock mechanism is in the latch) is binding on something. Take the door panel off and inspect the linkage and latch. You may have to take the latch out of the door to inspect it close enough.
Comment: @tester101 it's possible that the binding has stripped the gear inside the actuator so you may still need that, but you have to get the linkage moving first before you will be able to tell that
Comment: I hope that's the case, it will save me ~$120.00 if I don't have to buy a new actuator.
Comment: Turns out the assembly that the actuator interacted with was rusted causing it to be unmovable, a bit of liquid wrench solved the problem.

Automatic lock not working


Mac Book Pro 3,1 uneven startup behavior - sometimes start between 5min to 30min after pushing power button

Question: First of all, my Mac Book Pro won't start up after going to sleep mode - all black screen etc. When I choose power down from the menu, well, it doesn't power down completely. The hard drive is still running. Only when I hold down the power button will it power down properly. When I try to boot, the Mac book simply won't turn on; nothing happens until I keep pushing and pushing several times then it turns on, but there is no pattern to how many times I have to push the button. The super strange thing is that it sometimes turns on after a good while, say anything from between 5 min - 30m - 1 hour AFTER I've pushed the power button. And the Mac Book prior to that has no sign of being in sleep mode or anything at all, no heat or anything - just cold and dead. Then I turn my back and then as if nothing has happened it boots up!? I've tried several routines like taking off the power cord, dropping the battery, then holding down the power button for several seconds before then applying the power cord and again putting in the battery, etc. Sometimes this has an effect, sometimes not. Sometimes it seems it helps to take off the powercord immediately after pushing the power button several times, but maybe it's just luck. It also seems that my right USB is recognising devices slower than before and sometimes not at all. My left usb is dead.
Comment: Check your backup right away and kick one off if you get it to boot again....
Answer: Once you've gotten your backup - get into Disk Utility and try to repair the disk / consider an erase install. It will likely fail (unless the delay was caused by a very unlikely file system corruption or startup conflict).
Dropping a clean install - only the OS will let you know right away if the Hard Drive (HDD) can take new data or if other hardware issues are causing the half hour delay. Something fairly destructive is needed to cause a mac to take that long to successfully boot. Take it to a hardware tech if you have any doubts how to troubleshoot this, but odds are it's storage related.
Comment: Sounds like hardware to me, too.


Where do I post Stack Exchange-specific coding issues?

Question: I'm working on user-side CSS rules for better viewing of Stack Exchange.  I noticed there was no issue/bug tag on Stack Overflow.  I thought to post the question here, but I felt I would have a broader audience if using Stack Overflow itself.
Answer: If the question is broadly-relevant and concerns programming, then it should be asked on Stack Overflow. In other words…it is irrelevant why you writing the CSS. If you have an issue with CSS code, then you should ask for help on Stack Overflow.
If your question is unique to Stack Overflow and unlikely to be broadly-relevant, then it should be asked here on Meta. Issues/bugs relating to Stack Overflow itself (and/or its design) are to be posted on the Meta site, not the main site.
Just about anything is going to have a broader audience if you post it on Stack Overflow. It gets lots of views. But that is not enough reason to post a question there. You also have to ensure that it is on-topic. I understand that that this is what you're doing now, but reading that comment in your question is kind of like fingernails on a chalkboard to me.
I realize this answer is somewhat vague. The rules seem pretty simple to me, so your best judgment should be enough to figure out the appropriate site. It is difficult for me to be any more specific here, since you didn't give us any more detail about the question you wanted to ask.


Need to show oldest 3 items in one webpart and the remaining items in another webpart

Question: I have a scenario where I want to divide a list's items into 2 webpart views - one that shows only the x oldest items (people that should be seen next) and another list on the same page showing the remaining items.  This is like a "you are next" application that will display the people waiting and queue some to the top that were here first and are "ready" to be seen.
How do I accomplish this?  Not sure how to create the criteria that will update each time something in the list changes / is removed - and exclude those designated as the top 3 without replicating them.  Please help!
Answer: You need two separate web parts. For the first, Edit Web Part > Edit the Current View >

Sort by Created By / filter by some sort of open value
Item Limit = 3

For the second one, there is no way (without doing some custom code) to show just the remaining records. You'll have to show the whole stack in the other one, sorted as you'd like.
Comment: That was what I was doing, but noted that I could have duplication in my other list since there is nothing that I have that triggers or sets a  column value to know that a person is on (or not on) the top of the list..  Other ideas?
Comment: Personally, I would suggest having a field that is essentially some sort of column with possible values of 'Open', 'In process', 'Closed'. If you're using InfoPath you can do it all behind the scenes. If you're not, you can just default to open and have whoever addresses the issue close it. Then look at the list items that are open and order by create date.

It's never a fun thing to suggest extra columns, but you have to have some sort of status for these sort of things.
Comment: I am already using Infopath and a status field. I need to somehow show the remaining items without duplicating the top 3.  Is there a way to use a query web part that shows excluded items from the top webpart?
Can I use the date and time from the "newest created date" of the top 3 items and filter the bottom webpart based on entries that were created after that (so the oldest 3 are at the top webpart, and the others are in the bottom webpart?
I could also do something in Designer if that expands my options.
Thanks again for your feedback..
Comment: While you can do the top 3 easily enough w/ the above method, trying to 'split' into top 3 and non-top 3 is not part of the out of the box tool set. I would recommend using a REST service call and populate the data into two divs that way. The JavaScript for that would live in a script editor web part on the desired page.


DNA replication during Mitosis

Question: I am a bit confused.
During Meiosis, DNA is replicated to form a cell with half the DNA and likely to have variations.
But since the replication process of meiosis and mitosis are the same, why do DNA in different cells of an individual organism not have variations? Or do they have variations that are just not expressed?
Comment: Welcome to Bio.SE! In order to ask a good question, you are expected to show some research effort. Did you try googling "differences between mitosis and meiosis"? It could lead you to the answer!
Comment: So can DNA in hand skin cell and leg skin cell be same
Comment: Individual cells do have variations, those are just not inherited as during mitosis you don't produce gametes.
Answer: In meiosis crossing over takes place which leads to variations
 in chromosomes while in mitosis no crossing over takes place
Answer: Think of Meiosis as a means of producing half the genetic material you (and your partner) need which, once combined, produces offspring that inherits genetic material from the both of you. Think of Mitosis as a means of producing a full, exact (as exact as possible anyway) copy of chromosomes during cell division =)
Meiosis - results in a cell with half the genetic material (haploid), which is later fused with a similar haploid cell from the opposite sex (gametes) to produce a single cell with a full set of chromosomes (diploid cell). I.e. a sperm and an egg (each haploid) which fuse to produce a zygote (diploid). Important to note that during Meiosis, there is cross over between chromosomes, so that you end up with genetically diverse gametes (i.e. each haploid cell is different to one another - part of the reason your kids don't all look exactly the same).
Mitosis - results in a cell with a full genetic copy of the cell it was replicated from. That zygote will replicate using mitosis again and again until the organism dies. During Mitosis the cell tries to preserve as much of it's integrity as possible, so there isn't cross over. But the process isn't perfect in humans - each division results in shorter telomeres, and a cells also accumulate mistakes that result in "bad code" being passed on - UV damage for example.
With regards to expression, there is the concept of epigenetics - you may inherit certain genes, which (through various mechanisms) will be "locked" and not expressed in yourself, but may be expressed in your children. You might notice that kids have characteristics of their grandparents which aren't present in their parents.

DNA replication during Mitosis


Failed to extend contact lease for contact

Question: We have currently enabled the Sitecore OOB Personalization module, and have developed some custom conditions and actions to display a particular component on the website.
When a user authenticated on the sire, we are identifying the contact with a primary key, such that all interaction the user has done is associated with the primary key in the Mongo DB database later on.
Following activation of the Personalization module on our Production environment(which is a load-balanced environment), the component was working fine during testing. Yet, after some time we noticed that the component was not being displayed on a few individual servers. When we cleared the HTML cache on these specific servers, the component was working as required for some time but got hidden again afterward.
It was a random behavior that was happening with this component on different servers, and not on specific individual servers(there is no HTML cache enabled on the MVC rendering for the component).
In our logs, we noticed that the following errors were being obtained a few times on those individual servers
Exception: Sitecore.Analytics.Exceptions.ContactLockException Message:
Failed to extend contact lease for contact f217ae9d-a38f-4752-be0c-d824965f4d3b
Source: Sitecore.Analytics at Sitecore.Analytics.Tracking.ContactManager.SaveAndReleaseContact(Contact contact) at Sitecore.Analytics.Pipelines.EndAnalytics.ReleaseContact.Process(PipelineArgs args) at (Object , Object[] ) at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args) at
 Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, Boolean failIfNotExists)
at Sitecore.Analytics.Pipelines.HttpRequest.EndAnalytics.Process(HttpRequestArgs args)

Following the occurrence of this error on the server, we noticed that one of the following conditions was being set as true
if (Sitecore.Analytics.Tracking.Profile != null &&
 Sitecore.Analytics.Tracking.Profile.Count > 0)

for all contacts who were trying to access the site(noticed these in the logs when accessing the individual server where the component was not being displayed).
Can you indicate in which specific use case we get this type of issue?
You may find below the code snippet we have for the identification of the contact(the variable urn is our primary key)
ContactManager contactManager = Factory.CreateObject("tracking/contactManager", true) as ContactManager;
if (contactManager != null)
{
Contact contact1 = contactManager.LoadContactReadOnly(urn);
if (contact1 == null || contact1.ContactId == Guid.Empty)
    Tracker.Current.Session.Identify(urn);
else
{
    ContactRepository contactRepository = Sitecore.Configuration.Factory.CreateObject("tracking/contactRepository", true) as ContactRepository;
    if (contactRepository != null)
    {
                    Contact newContact = contactRepository.CreateContact(ID.NewID);
                    contact1.IsTemporaryInstance = true;
                    newContact.Identifiers.IdentificationLevel = ContactIdentificationLevel.Known;
                    newContact.Identifiers.Identifier = urn;
                    contactRepository.MergeContacts(newContact, contact1);
    }
  }
}

Comment: Which version of Sitecore do you use precisely?
Comment: @PeterProchazka Sitecore 8.2 update 4.
Answer: For web users, I think you are doing way too much work. If this was off Web Session and you needed to create contacts on the site, maybe in bulk, then this would be good code.
Under most circumstances, Sitecore does all the contact work for you. There is also no need for contactRepository.MergeContacts anymore, that is built in now.
Get Contact
var contact = Tracker.Current.Contact;

Get a logged in contact
Tracker.Current.Session.Identify(urn);
var contact = Tracker.Current.Contact;


What is entropy?

Question: We discuss a lot of topics and use measures of entropy to determine how difficult it is for an attacker to be successful. What does entropy mean in the context of cryptography? How is entropy calculated in the general case?
Comment: I think of entropy like this: Say the attacker wants to know your password and you are willing to tell her the password by answering her questions... What is the **minimum** number of questions with yes/no answer the attacker needs to ask in order to find the password?
Comment: Actually, if we have a 128 bit key (and  all $2^{128}$ possibilities have the same probability), that does have 128 bits of entropy
Comment: @PanosKal.That looks like a poor definition to me. For 128 bit key it would take me 128 questions to find the key (whereas the real entropy should be $2^{128}$). All I have to ask is "is the first bit a one?", "is the second bit a one?" and so on till the 128th bit
Answer: In information theory, entropy is the measure of uncertainty associated with a random variable.  In terms of Cryptography, entropy must be supplied by the cipher for injection into the plaintext of a message so as to neutralise the amount of structure that is present in the unsecure plaintext message.  How it is measured depends on the cipher.
Have a look at the following article.  It provides a survey of entropy measures and their applications in cryptography: "Entropy Measures and Unconditional Security in Cryptography (1997)" (by Christian Cachin).
Answer: To give you a short answer to your question: The common notion of entropy is the notion of Shannon entropy. The information content $H_x$ of a value $x$ that occurs with probability $\Pr[x]$ is
$$H_x = -\log_2(\Pr[x]) \text.$$
The entropy of a random source is the expected information content of the symbol it outputs, that is
$$H(X) = E[H_X] = \sum_x \Pr[x]H_x = \sum_x -\Pr[x]\log_2(\Pr[x]) \text.$$
You can interpret this as the expected uncertainty about a symbol $x$ knowing only the distribution according to which $x$ is chosen. For the case of bit strings the important message is, the entropy not always equals the bit length of $x$. I.e. if you want to seed a pseudo-random generator, it is important to choose a seed with high entropy. If you use the actual time as seed the entropy of the seed is very low, as everybody can easily guess parts of the seed (year, day, perhaps even hour and minute). Ask Netscape, they should have learned this…
There are several other notions of entropy all discussed in the other answer, but I think this is the most important one, if you don't want to study complexity or information theory.
Comment: What mathematically/exactly is $x$?
Comment: it is an element from the support of a distribution.
Comment: What I meant is that it's impossible to enumerate $x$ in the general case (non-IID samples). And then how would it be combined, as algebraic summation won't work? It's pretty much an open question. Hence your loggie formula is inappropriate in the general case as asked in the question. And of course, you don't know the expected information content either, so the entropy has to be the entropy of a fixed sample. Tricky and so it makes the answer incorrect.

What is entropy?


My Indian passport is damaged. How can I apply for a new one?

Question: Damaged Indian passport. To apply for a new passport what should be done?
Comment: Any reason you think it matters, and why you can't just do the normal process?
Comment: You still have that page?
Answer: It doesn't make much difference if the name, photo and passport number are still readable - see the following from the Embassy of India:

Damaged passport is classified further based on the extent of damage,
  i.e.:

Damaged Passport - Passport number is readable, name is legible and photo is intact
Damaged beyond recognition

To apply for duplicate passport in case of lost or damaged passport,
  you need to apply for "Re-issue" of passport.

To apply for a re-issue of a passport, like you'll need to - you follow the same steps as any person getting a new passport.  PassportIndia.gov.in has the application page with instructions - note that:

If you ever held a passport in the past, no matter how much long back
  or at what age, you should choose the Re-Issue category only.
Comment: Is it really a reissue?  I would infer that reissue applies only in thecar of a valid damaged passport, not an expired one.
Comment: @phoog the final sentence would seem to indicate expired passports too, damaged or otherwise.
Answer: Having a damaged passport does not preclude you from renewing or obtaining a new one.
But because your passport expired so long ago, you might check to see if you have to go through the original documentation process again or simply follow renewal procedures.


Our company shipped product to an address that the recipient just moved from

Question: The recipient moved and didn't notify us.  He moved 1 mile away.  Our tracking number showed delivery to his former address. The person said he went back and the new tenants said they didn't have it.  We shipped another unit to the person.  He received it.  The person said he then "convinced and persuaded" the new tenants to give him the package.  He now wants a "reward" for getting the package back.  We asked him to ship the "found" package back and he did.  He persists in getting a "reward" for getting the package back from the tenants.  Legally, what should we do?
Comment: "What should we do?" or "What are we legally obliged to do?" The former is off-topic and may be illegal to answer.
Answer: This post is tagged "fraud", but it doesn't appear to me that there is any fair indication of fraud in this situation. There is no indication that the customer tried to have the first package delivered to the wrong address. There is also no indication that it was the customer, rather than the new resident of the former address, who was not straight forward in their first communications with each other regarding the first package. And, the customer didn't try to keep the first package for himself.
So, this is not even remotely a case of fraud.
The issue seems to be that the customer feels entitled to compensation for benefiting you (a benefit you accepted) by taking efforts that he had no obligation to engage in, in order to cause the first package to be returned to you, on basically a theory of unjust enrichment.
There is a colorable argument that the customer is entitled to whatever he spent to mail the first package back to you and some nominal amount for his effort in doing so.
In the law of unjust enrichment, if someone does work with a reasonable expectation of getting paid, in the absence of a contractual agreement, and you allow that person to proceed with working and accept the benefit of his work, he is entitled to the fair market value of his efforts.
The classic case is that of a house painter who paints your house, rather than the house of a neighbor with whom he actually had a contract, by mistake. In that situation, if you know he is mistaken but allow him to paint your house anyway without objection, you have to pay him for doing so, even in the absence of an agreement to do so.
The reason that the customer's claim is only colorable, rather than clear, in this case, is that it isn't obvious that the customer had a reasonable expectation that he would be paid or rewarded for his efforts to get the first package returned to you. He clearly did have that expectation, but it isn't obvious that his expectation was reasonable under the circumstances.
Most likely, he would not prevail in a lawsuit against you for a reward and would not even try to bring one unless the first package was extremely valuable (if he managed to cause a $10,000 item to be returned to you the case "feels" different than if he managed to cause a $100 item to be returned to you).
But, while he is unlikely to sue you, so you could just say "no", he did do you a good turn and clearly would be quite upset if you said "no", which could lead to be reviews and/or publicity about your business. So, to preserve your reputation, you might want to pay him a reward equal to any cost he incurred to ship the first package back to you and some nominal amount of money relative to his efforts and your benefit from his actions.
This would maintain goodwill, the amount of money involved would be tiny in the larger scheme of things, it isn't likely to bind you to major expenses in the future, and to the extent anyone learns about it, it would encourage future customers to take action that leaves you better off than it they did nothing as the customer could have done.
Comment: Alternatively, a store credit reward would cost the vendor less than a cash reward.
Comment: @DaleM A great idea as a practical matter and one that would often be utilized in this situation and serves the twin goals of building a positive relationship with the customer and minimizing the cost of the interaction.


Max weight for Weber Coupling trailer

Question: My trailer is attached to my roadbike with a weber coupling system. How much weight can I pull safely without breaking my frame?
Comment: The frame is highly unlikely to be the limit. But what is the frame? Your road bike could be the lightest carbon bike on the market or a vintage steel frame. Very different answers. And for that matter what sort of trailer?
Comment: I should think it depends on frame material. What does the trailer manufacturer specify for the maximum load weight? Do they specify different maximums for different frame materials?
Answer: I can't comment on your specific hitch, here's a generalisation.
The normal quoted figure for an automotive trailer or caravan is ~45% weight on each wheel and 10% on the nose.
A bike trailer is likely a single axle - if yous has 3 or 4 wheels then it should stand by itself and noseweight is rough;y half the weight of the drawbar.

I've successfully pulled trailer with two heavy loads.
First was 68 kilos of car tyres, pulled for 20 km: thus

I've also carried 100 kilos of UPS hardware for 6 km.  That was right on the limit of comfort.  However I know the nose weight was around 9 kilos and each tyre carried 43-44 kilos.
NOTE This assumes your load is just stuff.  If you're hauling live people then absolutely stick to the manufacturer's recommended maximum weights.
Answer: There's tongue weight (the weight pushing your rear axle down from the attachment point) and towing weight (weight pulling the rear axle backwards).
Tongue weight is limited by your rear tire, but most should be able to handle another 50kg assuming the rider is not overweight. Most trailers are designed to be balanced such that there's minimal tongue weight although braking forces can change this.
Towing weight is dependent on your rear axle, rear dropout, and frame. It's also dependent on you the rider accelerating and decelerating smoothly. A mountain bike or touring bike will have the strongest frame.
People regularly tow loads of 80kg (200lb) of  children and groceries. People with utility trailers can tow canoes and loads of several hundred kilograms easily.  You just have to balance the load on the trailer so that it's over the trailer's axles and putting minimal tongue weight on the bicycle; and accelerating and braking gently to minimize towing loads and strain on your rear dropout. Thus, the trailer itself tends to be the limiting factor
Tl;dr: Your trailer should be list its maximum capacity. Assuming you have a bike with a strong frame and accelerate and decelerate carefully, your trailer is more likely to dictate its limit than the bicycle or mount point.
Tl;dr v2: Weber's website notes its coupler is suitable for loads up to 80kg. The coupler is made of stamped steel so is perhaps more fragile than other designs.
Comment: I'm sure Weber's rating of 80kg includes a considerable safety factor. An 80kg load should be safe in most normal circumstances, which would include towing uphill.
Comment: What if I pull 80kg up a 10% gradient?

Max weight for Weber Coupling trailer


VHDL: Component vs Entity

Question: I am wondering what is the difference between component an entity.
I would like to know in which cases is better to use components instead of entities.
Thank you so much.
Comment: You mean "vs" like in the title? Hm, not a good idea, methinks.
Comment: Not everyone here uses Visual Studio....oh wait...you meant the other "vs" right?  ;-)
Comment: Please, could anyone create a tag call 'vs'. Thank you.
Answer: Here's an analogy which helps some people (especially those from a physical electronics background):
A component tells the compiler "there's going to be something with these sorts of pins on it called this at some point, but don't worry for now".  It sort of defines a "socket".  You can go on to describe what "wires up" to that "socket" etc.
An entity is something specific with a name and a set of pins, which the compiler can then "plug in" to that "socket" (and hence be connected to the "wires").
Note that you don't need a component you can do "direct instantiation" which means the compiler already knows about an entity so the "socket" doesn't need to be defined separately.  In fact, that would be my recommended approach, as otherwise the component is an extra level to be kept in sync.
You need to use components if you are mixing Verilog and VHDL and need to use a Verilog block within the VHDL.  Then the component is the socket and not until much later on can the compiler/elaborator plug the Verilog into the socket.
Comment: Component is like the DIP package.  You could use the same 8-pin op-amp a dozen times in a circuit, and it's always 8 pins.  They are separate components, even though they're the same type of op amp.  Entity is like the pinout on the datasheet; all of the separate op-amps have the same pinout.
Answer: An entity is a real interface to a design unit which can have multiple architectures.  An entity defines how stuff gets in and out, while the architecture defines how the design unit operates. So you could have multiple ways of implementing the same function, which would be described by the same entity.
A component is an ideal or "virtual" design unit.  When you are doing a top down design (i.e. you are putting together top level before the lower level blocks are designed) you can use a component to describe the type of interface you are expecting for your design units. You can think of this as a place holder or black box for a future real implementation.
Using configurations you can bind a specific component instance to an entity definition. Here you can map out which port should connect to which port. This maps how the component that was defined in the ideal sense maps to the entity that was actually implemented.
In practice, I have found that components are typically unnecessary and create another level of abstraction that is typically not used.  You can skip the use (and need) for components by directly instantiating the entity and referencing which architecture to use for that instance of the entity.
For example:
MyDesignUnit : entity library_name.entity_name(architecture_name)
               port map(
                     ...

Comment: An [example](https://blogs.plymouth.ac.uk/embedded-systems/fpga-and-vhdl/test-benches/part-2-multiple-architectures/) of how to implement an entity with multiple architectures.  They use the implicit `work` library (so that would be your `library_name` in this case).
Answer: From [1] below:
There is an important distinction between an entity, a component, and a component instance in VHDL. The entity describes a design interface, the component describes the interface of an entity that will be used as an instance (or a sub-block), and the component instance is a distinct copy of the component that has been connected to other parts and signals. To compare these with the process of bread board design with off-the-self parts. The entity and architecture is like the data book describing the interface and schematics of how the part works. The component is like the short pin listing that comes with the part to describe how it should be connected. The component instance is the actual part itself, of which you may have many that each operate independently.
See [1] for context and more detail.

There are numerous VHDL tutorials on line eg  [2][3] ...
Book (84 page PDF) [4]
Looks good [5]
Mainly for links [6]

[1] http://www.gmvhdl.com/connect.htm
[2] http://www.seas.upenn.edu/~ese171/vhdl/vhdl_primer.html
[3] http://www.gmvhdl.com/VHDL.html
[4] http://lslwww.epfl.ch/pages/teaching/cours_lsl/sl_info/vhdl-tutorial.pdf
[5] http://www.doulos.com/knowhow/vhdl_designers_guide/
[6] http://instruct1.cit.cornell.edu/Courses/ee475/tutorial/VHDLTut.htm
Comment: Old brain :-). I lean towards maximum information (as you will have noticed :-)) and the endnote method allows readers to see where the link is from and whether some are on the same site - as sometimes happens. For very long links I'd tend towards using bit.ly / j.mp with a meaningful name. I've also seen users reticent about clicking on a link (even though these can be copied and pasted for checking (extra work)). BUT point noted and I'll consider each as options in future.
Comment: you seem to favor links in endnotes, but that's how it's done in print, and doesn't use hyperlinking like it's meant to be used. You could have written "See [this link](http://www.gmvhdl.com/connect.htm) for context and more detail". Much more user-friendly, AFAIC. Just a suggestion.
Answer: An entity is a design unit whose input-output ports are specified. Entity just defines the external ports while the internal functioning is specified by the corresponding architecture.
A component is the complete design unit composing of both entity and architecture. The first step is the component declaration( specifying its name and ports) and then component instantiation ( port mapping).

VHDL: Component vs Entity


Error in a "List Reversing" python program

Question: everyone!
I am a beginner in python programming. I am writing a python program to reverse a given input list. Following is the code for it:
    L1=list(input("Enter the numbers of list to be reversed : "))
    L2=[]

    def rever(La,Lb):
     if len(Lb)==0:
      return La
     else:
      return rever(La.append(Lb.pop(0)),Lb)

    print rever(L2,L1)

For example, if we input,
    1,2,3

The output should be,
    [3,2,1]

But this is not happening. Python is giving the following error:
    Traceback (most recent call last):
      File "Q3.py", line 10, in <module>
        print rever(L2,L1)
      File "Q3.py", line 8, in rever
        return rever(La.append(Lb.pop(0)),Lb)
      File "Q3.py", line 8, in rever
        return rever(La.append(Lb.pop(0)),Lb)
    AttributeError: 'NoneType' object has no attribute 'append'

I don't get it. Please help me out!!
Comment: you might want to check out this: http://stackoverflow.com/questions/509211/the-python-slice-notation
Comment: You can do it easier using: list[::-1] . But your way is a good exercise to learn about recursion ^^
Answer: may be you should look at this, instead of pop and append
In [5]: L1=list(input("Enter the numbers of list to be reversed : "))
Enter the numbers of list to be reversed : 1,2,3,4,5

In [6]: L1
Out[6]: [1, 2, 3, 4, 5]

In [7]: L2 = L1[::-1]

In [8]: L2
Out[8]: [5, 4, 3, 2, 1]

Comment: Or just use the reverse method `L1.reverse()` to reverse in-place. However, I suspect the OP is doing some kind of exercise.
Comment: yes it seems to be the exercise, hence i gave a slicing option rather than answering in pop and append, using python idioms is what OP should learn
Answer: There are a couple issues.  First the working way:
def rever(La,Lb):
    if len(Lb)==0:
        return La
    else:
        La.append(Lb.pop())
        return rever(La,Lb)

list.append appends in place, meaning it returns None.  Since you are passing La.append as an argument in the recursion, you get an error on the second iteration.
If you wanted to do it that way then you could do
return rever(La + [Lb.pop()], Lb)

The second issue is you are popping off the front and appending.  So you will get the same order.  Instead, pop off the end (no argument to pop) and append.
Answer: The append method operates in-place, altering the original list and returning None, giving you the error. Try this instead:
def rever(La, Lb):
    if len(Lb) == 0:
        return La
    else:
        La.append(Lb.pop())
        return rever(La, Lb)

You could also refactor your code to something like this:
def rever(La, Lb):
    if Lb:
        La.append(Lb.pop())
        return rever(La, Lb)
    return La

This uses the facts that an empty list is False in a boolean context, and there can only be one return value for any function.
Comment: Just FYI, this still doesn't reverse as it is appending the `pop(0)` item each time instead of using `pop()`


What is the reason terminal velocity changes with radius?

Question: I know that terminal velocity equals to some multiple of radius square. What is the physics behind this relationship. Is it just because as terminal velocity increases, the surface area increases and thus, a larger part of the object comes into contact with the fluid?
Comment: Related: https://physics.stackexchange.com/q/184546/25301, https://physics.stackexchange.com/q/337074/25301
Answer: Yes. Remember that terminal velocity comes from equilibrium between gravity and viscous friction, which depends on the size of the object.
Answer: Terminal velocity arises when net force on the body is zero.
Thus
 Buoyant force + viscous force = mg
We have the buoyant force as Vdg if d is density of fluid and V is volume of the body .
According to Stoke's law the viscous force as $ 6π \eta rv $
Thus both buoyant force and viscous force both depends on the size
Answer:
Is it just because as terminal velocity increases, the surface area increases?

I would say that you have the cause and effect backwards. The terminal velocity does not change the radius; the radius changes the terminal velocity. As the object size (radius) is increased, the weight increases (and the net force causing it to fall = weight - buoyancy force). To counter the increased net force, you need a higher friction force, and higher friction force is obtained by a higher terminal velocity.

thus, a larger part of the object comes into contact with the fluid?

The terminal velocity is related to objects that are completely submerged, so the portion of the object in contact with the fluid is the same.
Answer: Yes a larger radius means a larger surface area, which means a stronger drag force. The net forces are gravity pulling the object down, and drag pushing the object up. When the net force is 0, as in the force from gravity is equal to the force of drag, the object is traveling at its terminal velocity.
As radius increases, the force of drag increases.
terminal velocity (not considering buoyancy) is equal to the root of ((2 * m * g) / (density * area * drag coefficient))
As area, fluid density, or the drag coefficient increase, the terminal velocity decreases.
As mass or gravity increases, the terminal velocity increases.
Or, terminal velocity increases when the mass or the acceleration due to gravity increase, or when the density, area or drag coefficient decrease.
A falling object doesn't change its size, shape or mass easily. gravity and fluid density change with altitude though, and falling objects will slow down as the atmospheric density increases and the gravity decreases during the descent. Skydivers have some control over there shape, and can speed up or slow down during their descent by changing shape and therefore the drag coefficient.


When can embeddings be useful for small input spaces?

Question: I've noticed that some authors tend to use embeddings for almost everything. E.g. in the AlphaStar paper, or below an example for the OpenAI5 paper (link):

The Hero Embedding here encodes information about which hero out of 17 was picked. With 5 pickable heroes per game, that would yield a one-hot encoded vector of size 17 * 5 = 85. Instead, they chose to encode this information using an embedding. Does that not seem a bit overkill?
My understanding was that embeddings are very useful for large scale inputs, such as word-corpora, as they reduce the dimensionality nicely. What's the benefit of doing it on smaller inputs such as above? Is it just convenience? Or maybe I am misunderstanding what embedding means here?
EDIT: I wanted to add that EVEN if the Hero Embedding contains more unique information, such as health, mana, etc, then it would still be very small, likely under 200 values. So when does it make sense to start using an embedding, as opposed to using the values directly? What's the underlying thought?
Answer: The advantages of embedding is converting categorical variables to numeric variables. Those numerical variables have semantic meaning. Thus any valid mathematical operation for numerical values has interpretable meaning.
One-hot encoding just tells the model that two entities are different. Embedding tells how different the entities are.