Infected usb flash drive detection and cleaning

Question: Want to know what all type of malware infections are their that hides themselves in a pendrive completly and infects machine silently.How to detect this type of malware as they cannot be seen.
How to proceed for analysis.
Answer: Typically you would use an anti-virus program to detect and prevent infections from external storage devices. This is only as good as the AV protection installed. A good, up to date AV can protect systems against the majority of infections, but there is plenty of malware that use unknown vulnerabilities which will not be stopped by any AV program. So there's no way to prevent all malware infections from portable storage.
The approach many companies take is to prevent external storage from being used in the first place, which is inconvenient to users, but prevents that threat vector.
Comment: I am talking about what if AV cant detect hidden malware.As 4GB pendrive never shows full 4GB.It might be possible that some maleware is also present.So can we read the data of empty pendrive?
Comment: An empty pendrive has no data, so how could you read it?
Comment: It's not because the pendrive reports it's empty that it's actually completely empty :)
Answer: Unless your machine is already infected, a pen-drive should be able to be read if the virus is able to be run.  There are tricks to make it harder to find, but a good A/V should still be able to find it hidden or at least find the hooks it uses to make sure it gets executed when installed.
A slightly safer option than simply plugging it in and hoping your A/V does it's job is to use a Linux Live CD, boot in to Linux and plug in the thumb drive there.  Windows viruses are not going to work on a Linux install, so your computer would be safe as long as it doesn't have both a Windows AND a Linux virus on the same drive (which would be quite exceedingly rare as far as I know.)


Why are there holes in pasta dough when it is cold

Question: I made some pasta dough this morning and put it in the fridge. When I ran the first batches thru the roller there were some holes in the pasta after it came out of the roller. But for later batches, when the pasta heated up from being out of the fridge, there were no more holes. Why is that? I am partially asking about the chemistry and physics underlying this observation.
Answer: Viscosity of the cold dough is probably too high for good rolling. It's tearing and blobbing rather than feeding smoothly through the rollers.
I'm not finding a ref for rolling, but for extrusion:

The ideal temperature for pasta extrusion is between 45 and 50°C, as anything above 50°C will
  denature the proteins, impeding gluten production and therefore resulting in a soft sticky product.
  Using a cold water jacket will cool the dough and barrel too much, resulting in undesirable
  dough viscosity.

Nice plot of dough viscosity vs temperatures here (fig. 4.3), but it only goes down to 30°C (86°F) Lower temperatures, including heating within the extrusion die, are likely not usually encountered.
This pasta rolling cook states:

In making pasta it is important to avoid cold so use room temperature eggs.  Also, do not work on a naturally cold surface such as marble or stainless steel.


Photoshop vs Sketch 3 For app and Web design?

Question: So, I Have been looking into which photo editor to use for app designing and the web too. My only question if I make an app in Photoshop for the phone do I need to re scale it into the iPad size or is it vector like sketch 3? So basically while I have to make a tablet version and phone or just universal.
Comment: It depends upon *how* you construct things and what tools you use in Photoshop.
Answer: "If I buy a new car, can I jump sand dunes with it like I can in my motorcycle?"
...... yes you can. Will it jump better? worse? Be more fun? Well, all that depends upon how you drive, which can't be answered here.
Photoshop has a wealth of vector tools and features. If you create vector content within Photoshop.... it's vector content within Photoshop and like all vector content, it can be resized without any real issues.
Photoshop is, generally, one of the most used application for designers. Whether or not it fits your needs and your desires only you can determine. You will find users who prefer Sketch, just as you'll find users who prefer Photoshop, or Illustrator, or.. [insert app name here]
Answer: If you create it as a smart object within PS,  then resizing isn't going to be a problem. If it is a rasterized object then it it depends on how much or why it needs to be resized. The size is totally up to you , but if you are wanting the smallest possible size for each device then media queries with CSS will accomplish that easy enough if you create a few different sizes. When in doubt create/convert to smart object or keep it as a vector until you know for sure where you are headed with it.
Answer: It does depend on how you construct your elements. I'm an advocate for using Illustrator, which is not very typical. But I prefer being able to construct my screens (web, handheld, tablet...) by easily being able to enter actual dimensions for elements and positioning them exactly where I want them, usually b/c I'm respecting some sort of grid. I find that one has to eyeball it more or rely on the info tool panel to get elements positioned exactly. I'd say keep all of your elements vectorized as much as possible to avoid getting into resolution troubles when scaling in your designing and delivering. I recommend Sketch 3 and Illustrator for layout and svg creation, Photoshop for image manipulation and processing.
Answer: Sketch is ultimately much faster and quicker to work with. Getting used to the shortcuts may be a pain at first but you never have to worry about not designing in vector based shapes.
I have always been a photoshop/illustrator power user but at my new office they really like Sketch. Sometimes a bit buggy, but definitely much much faster than the alternatives.
Also much more affordable :)


Can I download a specific Mass Effect game from The Mass Effect Trilogy?

Question: So, I want to buy Mass Effect Trilogy but I don't have that much space on my ps3. (I want to buy the game digital) So, can I download the games individual? or do I have to download the 33 gb with the 3 games?
Answer: I bought the Mass Effect trilogy on PSN. It appears on my download list as three separate items that can be downloaded separately.
Answer: According to a post on Reddit, yes. It's likely the size you are seeing is what the combined size of all three games is. Here are the sizes from the same topic.
In my opinion, I would be surprised the game does not have individual downloads, considering the DLC, games, etc., really rack up and much of the games are dissimilar save a few oddities. Of course, the alternative (what I have done) is buy the disc set or each game individually (higher price), so I cannot confirm that.


Is there a difference between the terms 'elliptical' and 'elongated' for galaxies?

Question: While studying the Solar System, I found that some galaxies are either elliptical or elongated. What's the difference?
Comment: Please check a dictionary for the definitions of these words. If it is still confusing, edit the question to add the two definitions- with references- and elaborate on what about those definitions is confusing you.
Answer: tl;dr: "Elliptical" refers to a special kind of galaxies. "Elongated" is a loose term meaning that a galaxy is stretched out in one direction.
Etymologically, "elliptical" means having a shape that can be described by a certain mathematical function — the ellipse. For a three-dimensional object, the proper term is "ellipsoidal", but still it refers to being described by a certain equation. In contrast, "elongated" is a more loose term, meaning something like "significantly deviating from a spherical shape in one direction".
In the context of galaxies, the term "elliptical" refers to a certain type of galaxies that tends to be not actively star-forming, have no or very little structure (as opposed to the beautiful spiral arms of spiral galaxies), be quite massive, as well as other characteristica. Having no ongoing star formation, the massive, short-lived stars, which have blue colors, have died long ago, leaving behind the less massive, red stars. In addition, elliptical are often quite dusty, further reddening the light. Thus, ellipticals appear red in color.
The shape of an elliptical galaxy is described by the relative size of its three axes, $a$, $b$, and $c$. If two axes, say $a$ and $b$, are roughly the same size and are larger than $c$, the galaxy is said to be "oblate", whereas if they are less than $c$, it is said to be "prolate".
As in the etymological meaning, an elongated galaxy is not a specific type, but rather refers to a galaxy departing from spherical shape in one direction. This could for instance be a prolate elliptical, but it could also by any other galaxy that has been distorted by merging with another galaxy.
Usually, though (I think), it will refer to ellipticals. The "elongation" of an elliptical is defined as $10\times(1 - b/a)$, where $a$ and $b$ is now the observed axes, i.e. of the two-dimensional projection on the sky. Ellipticals are classified according to this number as E0 (being spherical, such that $a=b$) to E7 (being very elongated). In principle, you could have even higher E-numbers, but that's not observed.
Answer: Elongated means made longer. An elongated shape or object is stretched primarily in one direction.
Elliptical means having an ellipse-like shape. An ellipse is an elongated circle, where the elongation is done in a constant/linear way.
For example, a limousine often has the form of an ordinary car, elongated (an elongated car). It is not at all ellipse-like, however.
Answer: More simply, "elongated" is a general term that can be used to describe the appearance of any galaxy, and means more or less what it means in ordinary English.
"Elliptical" is a specific technical term for galaxies, and refers to galaxies which are in simplistic terms "round and fuzzy" -- made up primarily of stars on randomized three-dimensional orbits, with little or no gas and little or no current star formation, without a dominant stellar disk. They can be "elongated", but they can also be (intrinsically, or when seen at the right orientation) circular. There's a decent introductory Wikipedia article.


Using Android 2.0 with Exchange server behind firewall

Question: Blackberry has an enterprise server that works with MS Exchange, and pushes all updates to the user's blackberry devices. We are considering switching to Android phones, which supposedly support Exchange servers. Will there be a similar program for Android? Are there any configuration changes that have to be done on Exchange server? (Exchange is behind the corp firewall).
Answer: The aforementioned NitroDesk TouchDown should do the job, but HTC and possibly other Android phones have the ability to sync onboard already.
Setting up can be a little tricky, but here is a massive tip that will almost certainly help you get it working: use https://www.testexchangeconnectivity.com/ to test for ActiveSync connectivity, if it fails it often gives you a reason and almost always a solution to go with it.
Comment: +1 for bringing up TestExchangeConnectivity.com - it really is a great tool provided by Microsoft.
Comment: That testing tool helped, along with this article from Microsoft: http://support.microsoft.com/kb/817379. It does talk about disabling SSL but I know Android 2.3.3 has an issue with exchange ssl that was fixed in Android 2.3.4.
Answer: I use Nitrodesk Touchdown on mine.  I have found better with Exchange than my blackberry for me.  The whole Android experience is a little rough around the edges though, everything isn't as integrated as the BB.  To get the updates right away, you just need ActiveSync enabled on the Exchange server.
I used this 'work email' client with Exchange that was available, but that wasn't as feature rich.  I don't think Android 2.0 is released yet, so I don't think you will hear a lot about how it works in an enterprise setting.
Comment: Android 2.0 is the OS of the new Motorola Droid phone that is on Verizon so its is out now.  Supposably the HTC Eris will also get an upgrade once they work out some bugs with their SenseUI
Comment: I missed mentioning it yesterday, but happy belated 10K day.
Answer: As said before there is Active Sync.  But before swapping out all your phones, buy a couple and setup a couple of people with them.  That will let you see what it takes to set them up.  Have a couple of the user's use them as their only phone/organizer for a couple of weeks and see what they think of it.  Ideally use the lowest tech users you have, since they would have the most trouble changing.  Have them put together a quick list of things they liked and didn't like for everyone else, If they like it and are happy, the likely everyone else will too. If they hated it, it might be worth re-considering the change.  Or offer people the option.
Answer: For heavy MS Exchange user, they should stick with Windows Mobile. Nothing other then WM provide full support. i.e. two way inbox/sent item sync, multi calendars, private items, GAL.
However, the most important thing is that you don't need any APP to be installed on your device. AND, you don't need to install any Server side software. AND, the initial setup on WM device could be as little as 30 sec. AND, there should be less tech support calls. AND potentially less cost. And potentially quicker and better support on newer Exchange versions.
The only down side is... it's not "iPhone", "BlackBerry", and others will start to question about why you don't use those,
Comment: This is an entirely subjective response to your subjective answer - but very few people that I know with WinMo phones were happy with them, compared to users of BB.


What is the difference between Monero (XMR) and Beam (BEAM)?

Question: I would like to have a comparison between the privacy and scalability features of Monero vs Beam. I have heard some people say that these are privacy-oriented coins, and I would like to learn more.
Answer: Beam authored a similar piece on a comparison between Beam, Monero, and Zcash that I recommend you read here to get a different perspective. I personally disagree with some points, but the high-level details are more or less correct.
Pardon the image, but there is no way to create tables in StackExchange.

Beam's privacy is best characterized as "Monero with aggressive pruning and no ring signatures." Users who are unable to get access to old information cannot pull up past transaction information by looking at the current ledger state. However, those who receive transactions as they are broadcast can see the inputs and outputs for individual transactions. This effectively indicates whether outputs are spent, something that is not possible with Monero. I argue that the article overstates the privacy protections of "confidential transactions" in Beam. CT is a technology that hides transaction amounts, nothing else. The output transaction graph is hidden through obscurity of information, not anything committed on-chain.
Monero's scalability has improved significantly over recent years. Transaction sizes fell from ~13 kB to ~1.5kB. Monero now supports pruning, allowing users to ignore most of the information for old transactions. Still, Beam allows more information to be pruned, and they prune it much faster.
I did not include network privacy on this chart, since both Monero and Beam provide network privacy. Monero provides support for Tor and i2p, and it later will provide support for Dandelion++. Beam supports Dandelion++, and users can use Tor or i2p if they configure it manually. Transaction network obfuscation is important, but it's less important for most people than graph protection.
I like to think of Monero and Beam as projects that are pushing the privacy and scalability boundaries, each beginning in different positions. Monero is focused on a privacy angle with scalability second, whereas Beam has the opposite focus.
Comment: This is fairly outdated and somewhat inaccurate by this point. BEAM uses a combination of Lelantus-MimbleWimble with Dandelion routing mechanism that does not store any transaction info or amounts on the blockchain to keep everything anonymous. It also has the best in class privacy or Max Privacy transactions with an anonymity set of up to 64K vs Monero's just 16 and this isn't even considering BEAMs other amazing features like built-in atomic swaps, confidential assets, private smart contracts, etc.
Comment: Here's a good [medium article](https://medium.com/beam-mw/beam-the-best-in-privacy-59023593c06) explaining BEAMs privacy features
Answer: Beam is providing better privacy and much better scalability and IBD time than Monero. During the Dandelion stem phase, before the TXs are broadcasted to the P2P layer, they are being CoinJoined together. This is done by both Grin and Beam. Beam novel addition is the use of Decoy Outputs (Dummy Zero Outputs) which are being added when needed. Those decoys look like any other output in the system and they are totally indistinguishable from other outputs (unlike Monero decoys). They are later being spent at a random block height, so no permanent clutter on the blockchain. This mechanism is very effective in breaking linkability. Beam and Grin are using FlyClient tech to allow extremely fast trust-less sync with the network. It shows on the mobile clients which are unmatched in the space in terms of fast sync without the need for a server size.
Resources:

Bitcoin Q&A: MimbleWimble and Dandelion
Grin Privacy Primer
Beam's Transaction graph obfuscation
Flyclient: Super-Light Clients for Cryptocurrencies
Look at Fast Sync vs Full Sync (2nd graph from the end) to understand Mimblewimble huge advantage in scalability. IBD for a full node is extremely fast. Beam Community Block Explorer
Download mobile clients and see FlyClient advantage Beam Downloads page


How much is a small/medium/large onion?

Question: By size or weight - I never seem to know ...
Answer: Here's some general guidelines I have used in the past:

Small onion = 4 ounces by weight or
about ½ cup chopped
Medium onion = 8 ounces, or about 1
cup chopped
Large onion = 12 ounces, or about 1½
cups chopped
Jumbo onion = 16 ounces, or about 2
cups chopped

source
The terms are not always completely accurate so use your best judgement. I've often seen large onions that were as big or bigger than "jumbo" according to this data.
Answer: While not scientific, I think some ingredients are best left to the idea of artistic interpretation -- or in chef vernacular, "to taste".  Onions are the perfect example of this.  Like onions just so-so?  use medium sized ones.  Love 'em?  Go large.  Hate 'em?  Go mini...and dice it really, really small.
NOTE: Skip jumbo.  It's a bad category regardless of your affinity for the root.  For most all  veggies, it's ideal to buy small or medium, because smaller sizes maintain better flavor.  The larger ones have often gained their girth through water weight...making for pithy textures and disappointing taste.  Think watered-down chicken soup.
Answer: This may not help you distinguish between small and large, but will put relative sizes in perspective: Remember that volume is proportional to the cube of the girth. So it doesn't take much additional girth to increase volume substantially.

An increase of 25% in girth nearly doubles the volume.
An increase of 50% will more than triple the volume.
And doubling the girth gives you eight times the yield.
Answer: If you look at the recommendations of the US National Onion Association you'll see that a small onion can be anything between 1" and 2.25" in size.
In sheer volume the difference is staggering.
Then if you chop or slice it the next inaccuracies appear. How thinly or finely do you chop.
Then the taste, the amount of volatiles in the onion play a role; after all the volatiles give onion its taste and smell.
So, it is up to your personal taste. Use it as a guideline, chop an onion, taste it raw and cooked and then add as much as you would like.

How much is a small/medium/large onion?


Information on ISS orbit?

Question: Does anyone know the ascending node and periapsis for the ISS?  This is for a MATLAB script.  I cannot find it on the internet and figured that this would be a good place to ask.
Comment: Data for satellite orbits is generally published in Two Line Element or TLE files. If you google ISS TLE, you should find several hits.
Answer: You can find the recent data on Heavens-Above.

Epoch (UTC):    27 July 2018 17:07:00
Eccentricity:   0.0005177
inclination:    51.6392°
perigee height:     402 km
apogee height:  409 km
right ascension of ascending node:  176.7268°
argument of perigee:    353.8799°
revolutions per day:    15.53762294
mean anomaly at epoch:  6.2290°
orbit number at epoch:  481

Due to low orbit and resulting air drag, plus periodic reboosts, that data shouldn't be treated as fixed/long-term; the orbit changes over time a lot.
Comment: If the orbit changes over time a lot, what is the use of writing so many digits for revolutions per day? Within one orbit, some of the least significant digits will be different anyway.
Comment: @Uwe: the point is not customizing specific entries in a general system. ISS is not the only object tracked.
Answer: Another answer links to Heavens-Above, which is a pretty good source. However you might cut out a middleman and get the data directly from NASA's Human Spaceflight Center.
Today's values include
<code>Coasting Arc #19 (Orbit 673)
---------------------------------------
[...]
Satellite: ISS
Catalog Number: 25544
Epoch time:      18221.12611709   =   yrday.fracday
Element set:     918
Inclination:       51.6406  deg
RA of node:       114.8775  deg
Eccentricity:     .0005396
Arg of perigee:    39.6633  deg
Mean anomaly:     320.4914  deg
Mean motion:   15.53822846  rev/day
Decay rate:    1.67170E-04  rev/day^2
Epoch rev:             674
Checksum:              315
</code>
Note that I'm writing this answer on July 27, but the epoch of the data set quoted above is the 221st day of the year, which is August 10; it is the 19th set of predictions that's available as I look.
As your other answer says, the orbit of the ISS is non-Keplerian because of its interaction with the atmosphere and occasional correcting boosts.
Comparing different sets of orbital parameters might let you learn some interesting things about the way the orbit evolves over time.
Comment: You should spend more time here. Plenty of physics related questions.

Information on ISS orbit?


Why does extrinsic motivation sometimes reduce intrinsic motivation?

Question: Why is it that if a person likes subject X but then when he gets paid for it he doesnt like it anymore. What causes this?
Comment: While this might be the case in some cases (you do not cite what this assumption is based on, so -1), it is important to note this is not always the case! In addition to [the answer provided by H.Muster](https://psychology.stackexchange.com/a/4212/21), be certain to check out the ['Controversy'](https://en.wikipedia.org/wiki/Overjustification_effect#Controversy) section on the linked Wikipedia page. E.g., _"In fact, a 2001 meta-analysis showed that rewards can increase intrinsic motivation for tasks that initially hold little intrinsic interest."_
Answer: This effect has been termed Overjustification effect and was originally reported by Lepper, Greene & Nisbett (1973) who studied the influence of rewards on intrinsic motivated behavior.
Some theories hypothesize that the reward reduces the feeling of self-determination, which in turn reduces intrinsic motivation, because the reward induces the feeling of being controlled by the person that offered the reward.
References
Lepper MR, Greene D, Nisbett RE (1973). Undermining children's intrinsic interest with extrinsic reward: A test of the 'overjustification' hypothesis. Journal of Personality and Social Psychology 28 (1): 129–137. doi:10.1037/h0035519.
Comment: As a reference, I would like to add the cognitivie evaluation theory (Deci) and Motivation Crowding Theory (Frey)
Comment: This answer might need to be qualified in order to take into account [this is not _always_ the case](https://psychology.stackexchange.com/questions/4211/why-does-extrinsic-motivation-sometimes-reduce-intrinsic-motivation#comment39798_4211).
Answer: To understand Extrinsic motivation to do something think of the carrot and the stick theory. So one only does something because they have to, ie, for some reward for due to some fear of penalty. Think of when our parents "made" us do the dishes. Thats an example of an extrinsically motivated act. Whereas Intrinsic motivation  is when we do something because we want to. So sometimes what starts out as an extrinsic motivation becomes internalised within our belief system and it actually becomes somewhat intrinsic. for example, our parents instil in us to brush our teeth every night and then when we become parents that becomes our own own intrinsic value. however without going into too much detail, it is still an extrinsic motivation while being classified as a subset of extrinsic motivation because it has almost the most of the elements of intrinsic motivation the only difference being is that it is an internalised extrinsic motivation. So to address the question, the extrinsic motivation has not interfered with the intrinsic motivation.
A study showed that once a reward was offered to people who were intrinsically motivated, they actually lost interest. however when praise was offered instead of reward, the intrinsic motivation was maintained or increased.
References
Deci, E., & Ryan, R. (Eds.), (2002). Handbook of self-determination research. Rochester, NY: University of Rochester Press
Comment: *Disclaimer* my friend answered this question on my account, I am trying to get my friends to create their own accounts and answer questions *sigh* lol


What sort of mathematical background is necessary to learn ethical hacking?

Question: Do I need to be a "mathematical whiz" to be a hacker?
Comment: You don't need any math background unless you're going for crypto stuff. I've also worked with some people who literally have a 3rd grade math level, but are very good at programming/hacking. Having said that, Math will help with logical skills and thinking. I would not recommend neglecting it, but if you can get around without it... by all means, do what you want.
Comment: No, but you do need to be a mathematical whiz to own the name `Michael Bloomberg`. Also, you don't even need to be able to factor large numbers, unless you wish to solve the [RSA Challenge](https://en.wikipedia.org/wiki/RSA_Factoring_Challenge) in your head.
Answer: Do you need it to just run hacking attacks or simple social engineering?  No math is needed.
However, if you want to be an expert and really understand modern cryptography, you'll need to learn some rather advanced/obscure math like modular arithmetic, Fermat little's theorem, discrete logarithms, etc.  You don't need to understand cryptography to use it, but if you want to implement it, or search an implementation for flaws/vulnerabilities, you'll need to understand it.  Have a look at Handbook of Applied Cryptography and you'll see there's a fair amount of math, that likely is unfamiliar to you.
Say you know that all passwords in a system are comprised of 12 random characters (case-sensitive including special characters) (and some salt) and you have the salt+hash, and want to break it with a GPU that generates a billion hashes per second.  Is it worth trying to break?  What about if passwords were 6 random characters?  The answer from basic probability/counting/conversions is don't try with the first one (should take million years); but the second should be trivial to crack (done in under 5 minutes)?  Some security algorithms (like Microsoft's LM-HASH ) didn't recognize this basic fact that two N/2-length passwords could be cracked in ~10 minutes while one N-length password may take a million years.
Its hard to say a priori what you don't need to know; as sometimes understanding something can help tremendously,  see relevant (and today's) xkcd.  Math is also great at just teaching you to think very logically; sort of like how doing a push-up isn't very useful on its own -- but being in shape/strong from doing push-ups is quite useful.
Answer: I would say that, rather than mathematical skills, you require logical skills.
Maths is important, of course, but not in the sense that you could apply mathematical concepts to hacking (examples: derivatives, integrals), but meaning that it could give you the tools and the training needed to help you with your problem-solving skills.
Answer: Definitely not.
Computer science can be divided in several sub-classes. I'd say security is not the most mathematically challenging field among those, in contrary to fields that research numeric methods to solve problems, for example.
That doesn't mean that mathematics are unimportant at all from the perspective of a security researcher (or hacker, if you will), but like user1301428 said: you have more need for logical skills as well as creativity and imagination.


Start workflow from within a workflow?

Question: I have a workflow that is created from a default "Approval" template, and the basic startup conditions are not enough for my purposes. I also can't open this workflow in SP Designer (it doesn't even show as a workflow in Designer). So, is it possible to kick off this workflow from within another SharePoint Designer 2010 workflow? In this way, I can specify a condition that must be fulfilled in order to start the Approval workflow. I checked under the available actions and it doesn't look like one of the options.
Answer: Starting a workflow from a workflow is not there OOTB.  You can extend the available actions either by writing your own or using something like the SPDActivities on codeples ( http://spdactivities.codeplex.com/ ).
there are other methods where you can utilize multiple lists/workflows to achieve similar results, but without really knowing what the "condition" is you are trying to check, can't say that will work for you.

Start workflow from within a workflow?


What are the possible test scenario's to test a Text field?

Question: Consider the text field accepts alpha-numeric characters. What could be some unique and out of the box test scenario's/cases that could be useful in finding an important defect.
Answer: It depends on what the text field is supposed to accept and what it's for.
If it's meant to accept specific formats of data, your tests will be different than if it's meant to accept free-form data. For example,  text fields are often used for postal code entry. For that, there's likely to be validation that the postal code format matches the official format for the country (USA: xxxxx or xxxxx-xxxx where x is any number, Australia: xxxx where x is any number - those are the only two I know offhand).
Some other considerations:

Is there a way to get invalid input into the field? Most browsers will allow drag and drop or copy/paste into fields: this is a common way to put invalid data into a field. The key thing is to handle the invalid input gracefully.
Is there a way to override the field length limitations? Copy/paste and drag and drop can do this. I've also seen holding down a key do it, particularly if a control key is involved.
Are there limits on the characters the field should accept? If you're limiting to English alphanumeric, the field needs to handle other characters gracefully.
Special character handling - does the field handle characters that have specific meanings in HTML, JavaScript, the back-end programming language used, SQL? Does it handle leading spaces? Should it handle leading spaces?
Answer: Do you have some requirements at first about text field? There are some basic checks:

Check possibility to input minimum number of symbols
Check possibility to input maximum number of symbols
Can you input uppercase and lowercase together?
Can you input special symbols?
Can you copy and paste inside text field?
Check different unicode symbols
Check cyrillc
Check arabian

Etc. I hope this tips could help you.
Answer:
Max/Min-length (Display and correct after save/reload)
UTF-8 display support (I use the UTF-8 Sampler data)
Server-side validation of UTF-8 length (Multibyte chars are sometimes counted as two chars)
Clear (Backspace, delete)
Cut and paste

To visually verify the length fast I created a file which looks like this:
0--------10--------20--------30--------40--------50--------60--------70--------80--------90--------'
100------`---------`---------`---------`---------`---------`---------`---------`---------`---------'

Comment: Error 404 - Not Found. Apologies, but we were unable to find what you were looking for. Perhaps searching will help.
Answer: Based on requirement for the text field scenarios will differ.
Suppose when we try to prepare scenario for name fields.
1.Check with Equivalence (i.e.)
Maximum length of field,
Minimum length of field,
Exact field length,
Numerical,
Alpha numerical,
Special characters,
Empty field,
Enter input into text box,
Copy and paste,
Try with browser cache .
Answer:

Comment: !DOCTYPE html>

manual testing - What are the possible test scenario's to test a Text field? - Software Quality Assurance & Testing Stack Exchange

    <link rel="search" type="application/opensearchdescription+xml" title="Software Quality Assurance & Testing Stack Exchange" href="/
Comment: I want to know HTML contentents can be added in the message box or no?


Which way are downstream and upstream services?

Question: For a system that consist of multiple services calling each other (e.g. Front End -> Backend -> Storage), I often heard people using terminology such as "downstream" or "upstream" services. I'm not clear which direction these mean. Data flows in both direction. Requests flow from more user-facing to more backend service, but responses flow in the opposite direction, so it seems to me one either way can be argued
Comment: Interestingly, the HTTP specification RFC 7230 happens to include definitions of the terms "upstream" and "downstream" in Section 2.3: https://tools.ietf.org/html/rfc7230#section-2.3
Answer: The downstream services are the ones that consume the upstream service.  In particular, they depend on the upstream service.  So the front-end is downstream to the back-end because it depends on the back-end.  The back-end can exist meaningfully without the front-end, but the front-end doesn't make sense without the back-end.
The dependency doesn't have to be as strong as I made it out to be in the previous paragraph.  More generally, upstream services don't need to know or care about the existence of downstream services.  Downstream services care about the existence of upstream services, even if they only optionally consume them.
Comment: It takes some real contortion to think of it like this answer. Much easier to think in terms of the dependency chain and use the river analogy.
Comment: I think it should be *"downstream services"* in place of *"services downstream"*.
Comment: easy metaphor for remembering which is upstream and which is downstream https://softwareengineering.stackexchange.com/a/395738/74944
Comment: This seems to not fully agree with https://tools.ietf.org/html/rfc7230#section-2.3
Upstream and downstream are with respect to messages, which go both directions.
Answer: The best way to think about this is to think of a river.
The downstream part of the river cant get any water unless it comes from upstream i.e. downstream is dependent on upstream for its water.
If someone destroyed the downstream part of the river, this would have no impact upstream. If someone destroyed the upstream part of the river, this would impact downstream i.e. it wouldnt get any water.
So downstream services depend on upstream services. If the upstream services are removed, the downstream services wont work properly.
Comment: @Delioth disagree. The backend can have many clients, but doesn't depend on any single one of them. If you removed a client, backend would still work. The client can have many backends it could use. If one backend is removed without the client knowing, the client can't work properly. Client is downstream. Backend is upstream.
Comment: I guess it is just a difference caused by some people thinking about it in terms of flow of message/control, while some others thinking in terms of flow of dependency?
Comment: And for the extra bit of clarity; in a standard CRUD client-server relationship, both ends are both upstream and downstream to each other. The client can't get any data or updates if the server's down, and the server doesn't have any instructions to execute if there isn't a client.
Comment: I have seen nginx/apache in reverse proxy context calling the backend services as upstream services. Then I saw an API gateway called ocelot that call the backend services as downstream. That is the reason why I'm reading this thread.
Comment: This discussion shows the terms are confusing when used in context of dependencies and bidirectional data flows (like request+response). I therefore suggest to only use them when the directionality is very clear: up=before, down=afterwards (e.g. batch processing)
Answer: Unfortunately there are differences in opinion on the meaning of upstream/downstream.
When talking about system architecture, I define it as follows:
Given a system of concern, systems that initiate messages/data exchange to the system of concern are upstream systems, and systems that the system of concern depends on (i.e. those to which my system initiates data exchange) are downstream systems.
This link from ibm describing interactions with one of their products corroborates this view:
Integrating with upstream and downstream systems

An upstream system is any system that sends data to the Collaboration Server system. A downstream system is a system that receives data from the Collaboration Server system.

Given the terminology 'upstream' and 'downstream' it may help to make an analogy with a river. If you drop a message (data) in the river it flows from upstream (initiator) to downstream (receiver).
Anecdotally, I've found that architects and middleware developers use this definition and web developers the opposite (maybe due to 'upload'ing).
With Event timelines, an event is upstream when it happens before a point on the timeline (i.e. triggers another event) and downstream when it happens afterwards (i.e. received the event). What is upstream and what is downstream in a sequence of events, therefore, depends on where you are in the timeline. An event can be both downstream and upstream, depending on whether your starting point is before or after it.
As @Jack notes RFC7230 tools.ietf.org/html/rfc7230#section-2.3 has this:

The terms "upstream" and "downstream" are used to describe
directional requirements in relation to the message flow: all
messages flow from upstream to downstream
Comment: This is just confusing because you are confused yourself on the matter. There is no discrepancy, just a difference in point of view.
Comment: @MartinMaat I disagree with your first sentence, and agree with your second.
Comment: Not sure which context this reply is in reference to--apparently not web apps and microservices: "systems that initiate messages/data exchange to the system of concern are upstream systems" --the term "initiate" suggests a request (e.g. a GET) from a dependent--i.e. downstream system (not upstream system) per the other answers.
Answer: This may be more a linguistic and geographical problem than a technical one.

The request for information goes upstream. It comes from a downstream
system.
The response to the request for information (the requested
information) goes downstream and is sent by an upstream system.

There is no difference between the classic IBM view and today's web community's use of the terms.

A service provider (server) will be located upstream compared to a service consumer and sends information downstream to the consumer.
A service consumer (client) will be located downstream compared to the service provider and sends requests upstream to the provider.

Theoretically roles of physical systems could change instantly and so would the direction of the stream between those systems. In a peer-to-peer network this may be the case.
The terms uploading and downloading are client centered terms.
From the client's perspective a request is uploaded and a response is downloaded, which is consistent with the stream metaphor.


Water and Ice - density

Question: We know that ice has a lower density than water despite both having the same [molecular] mass. I know that as water turns to ice, it expands. As far as I was taught, I know that it has something to do with hydrogen bonding. I would like to know in terms of hydrogen bonding, why ice actually expands?
Comment: Note that water is far from being the only compound that has a liquid with higher density than the solid at the melting point. Elements such as Si, Ge, Sb, and Bi do as well, and they certainly have nothing to do with hydrogen bonding. The only real certainty is that a first order phase transition must have a volume change.
Comment: I'll point out that chemists use "water" in two different ways. First it just means the chemical with the formula $\ce{H2O}$. Second it can mean more specifically the liquid state of $\ce{H2O}$. Also planetary scientists refer to a number of compounds as various kinds of "ice" that would coat the surface of a planet.
Answer: The most straightforward answer is that water in the form of ice I (or $\ce{I_h}$) has an open hexagonal structure (see figure) whereas liquid water does not. In ice the oxygens are precisely tetrahedrally positioned where each oxygen is hydrogen bonded by four neighbouring oxygens with an O..O distance of approx 0.28 nm. The H atoms lie very closely along the O-O axes. Two of the H bonds are short, as in liquid water, and two are long. This is expected from residual entropy calculations and also from thermal and neutron diffraction experiments.
As this ice structure has a rather open lattice this is the reason its density is less at its freezing point than that of liquid water, rather than being due to the high density of water. One could argue that the reason that water density is a maximum at 4 $\ce{^0C}$ (277 K) is that the structure of  liquid water is changing from that of ice $\ce{I_h}$ to the short range structure of the liquid.
Liquid water is, of course, also highly hydrogen bonded but the extra energy it contains means that its structure is far less regular and so becomes slightly denser than ice. As the water molecules can move about more in the liquid than in ice, the hydrogen bonds will bend a little or break as molecules rotate. This will lead to a shorter O - O distance and hence slightly higher density in liquid than in the solid.
see also answers to this post Why really is ice less dense than water?

This figure shows the hexagonal ice structure; The O atoms are shown as dots and the lines are the (almost linear) O-H-O bonds.(Image from Murrell & Jenkins 'Properties of liquids & solutions')
(Ice also exhibits eight different phases depending on temperature  and pressure of which $\ce{I_h}$ is the one found at normal atmospheric pressure. In these other phases, angles are distorted from being tetrahedral)
Comment: Could you explain the structure of water a bit more? How irregular is it?
Answer: Straight from Wikipedia...

The density of water is about 1 gram per cubic centimetre (62 lb/cu ft): this relationship was originally used to define the gram. The density varies with temperature, but not linearly: as the temperature increases, the density rises to a peak at 3.98 °C (39.16 °F) and then decreases. This unusual negative thermal expansion below 4 °C (39 °F) is also observed in molten silica. Regular, hexagonal ice is also less dense than liquid water—upon freezing, the density of water decreases by about 9%.
These effects are due to the reduction of thermal motion with cooling, which allows water molecules to form more hydrogen bonds that prevent the molecules from coming close to each other. While below 4 °C the breakage of hydrogen bonds due to heating allows water molecules to pack closer despite the increase in the thermal motion (which tends to expand a liquid), above 4 °C water expands as the temperature increases. Water near the boiling point is about 4% less dense than water at 4 °C (39 °F).
Other substances that expand on freezing are acetic acid, silicon, gallium, germanium, antimony, bismuth, plutonium and also chemical compounds that form spacious crystal lattices with tetrahedral coordination.
Comment: @MaxW It's ultimately preferable to use the external text/graphics to illuminate your own answer. I am confident that you have more you can add to the answer than just the raw explanation.
Comment: First, this is basically a plagiarising answer as it builds entirely off its source. Second, this does not answer the question *why* water is more dense than ice.
Comment: @Jan - the *why* - "These effects are due to the reduction of thermal motion with cooling, which allows water molecules to form more hydrogen bonds that prevent the molecules from coming close to each other." // I said explicitly that I lifted the answer from Wikipedia. The whole point was that I thought the OP should do some simple research.

Water and Ice - density


50 Ohm coaxial cable vs 450 Ohm or 600 Ohm ladder or window line?

Question: What are the relative advantages and disadvantages of using 50 Ohm coaxial cable as opposed to 450 Ohm or 600 Ohm ladder or window line?
Answer: The primary advantages of coax with respect to ladder line are

most transceivers are equipped with coax connectors, whereas using ladder line requires a balun or balanced tuner
coax is not affected by nearby metal objects, unlike ladder line
the impedance of coax doesn't change when it rains or snows, unlike ladder line

The primary advantages of ladder line with respect to coax are

lower loss at frequencies of 28 MHz and up
easier to make connections
can drive a balanced antenna (e.g. a dipole) without a balun
lower weight
Answer: Cheaper & less loss
The main advantage of two-wire transmission lines over coaxial cable is, apart from reduced cost, also much lower loss. This is because the dielectric in two-wire lines is predominantly air. Plastic dielectrics provide more loss.
In that respect, open-wire line has the least loss of all two-wire transmission lines, window-line a bit more and twin-lead ribbon line even more so.
Loss measurements
A classic paper by Wes Stewart, N7WS reports on loss measurements of 450Ω "Wireman" window-line. An impedance-matched, 100ft length of medium-grade type 552 window-line showed 0.24dB loss at 20MHz under dry conditions. In contrast, the ARRL Antenna Book reports for an impedance-matched 100ft length of RG-213 coaxial cable at the same frequency a loss of slightly more than 1.0dB.
Additional mismatch loss
Please, notice twice the use of the word "impedance-matched" in the previous paragraph. This is because a mismatched line will suffer additional power loss. The maximum voltage and current amplitudes on a mismatched line are proportional to the square root of the standing-wave ratio $(\sqrt{SWR})$. This increase in effective current raises the ohmic losses $(I^{2}R)$ accordingly, whereas the increase in effective voltage increases the losses in the dielectric $(\frac{E^{2}}{R})$.
Typical use case
From a practical point of view, suppose you happen to have a severely mismatched antenna and you chose to perform the impedance matching not at the antenna but in the shack. In such a case, it is in your interest to use a two-wire line of sufficient voltage and current rating over a coaxial cable. Not only will the loss and cost be much lower than with coax, also a voltage breakdown of the dielectric will be less likely to occur.
For insanely high power levels (broadcast), four- and five-wire lines may offer a solution.
Comment: For "insanely high power" professional broadcast systems use coax. Period. The 500 kW transmitters at the Voice of America used coax built from a central circle of wires surrounded by a bigger circle of wires. It is built from "open wire", but it is a coaxial transmission line.

The only other transmission line used for high power is waveguide.
Comment: @WalterUnderwoodK6WRU Statements that require strengthening with a «Period.» rarely happen to be well argued… Surely, coaxial transmission lines made out of a couple of concentric wires are commonly found in high power broadcast stations. This does not take away from the fact that, at least here in Europe, [two-wire transmission line is equally common in broadcast](https://upload.wikimedia.org/wikipedia/commons/a/a4/Rundfunksendeanstalt_J%C3%BClich_-_Christian_Vision_%287626-7-8%29.jpg).


Can I rescue leaning concrete forms?

Question: I'm adding to my deck. I marked off 6 holes, and dug them about 30" deep. Then I set tubes in, letting them extend about 8" above ground. I put a couple inches of rock in the bottom. I made sure the tubes were level. I mixed concrete and filled the tubes while tapping concrete. I had back filled aroind tubes first. We had heavy rain that night and now I have 3 tubes that are leaning about 1/4" to the inside of new deck. The deck is about 5 feet off ground. Can I save these or do I need to destroy these footings and start over? I have about 140 pounds of concrete in each tube. I set 6 tubes for a 10 x 12 deck. I live in the St. Louis area.
Comment: did you set anchor bolts in the top of the concrete?
Comment: Yes i do and haven't looled here for a while and it was suggested that I frame in a box with 2x6's which I did and it worked. Thanks for your interest and I know if I ever have any issues in the future to address it on-line
Answer: Actually, now that I think about it, I've seen pros pour posts that were worse than that, and it didn't rain!  lol.  Don't think you're in bad shape.  You can certainly use them.  Try packing the downward leaning side hard with a dirt tamp, you just might get that 1/4" back. Don't be afraid to use the pull and grunt method. Brute strength. Being only 30" deep, you may be able to force them back to plumb and compact the voided side with a tamp and some fill.

Can I rescue leaning concrete forms?


Borrow money to move abroad

Question: I live in the UK, and I am planning to leave the country next year for another European country.
I have lived in this country for more than 5 years, and I have an excellent credit score. I have also savings, let's say 10k, and I would like to ask for a personal loan of equal amount to cover the expenses related to the move (deposit for renting another house, expenses to move all my things, etc.). I do not want to use my savings because I would like to keep that money available in case of emergency.
I have been a customer of my bank since I moved here, there is a possibility to open a bank account with them abroad, and even that I will move in a country where they have physical branches (even though I am not sure that I will move in one of those countries).
Will a bank allow me to borrow with such reason? or going abroad is a too high risk for them?
Answer: With a suitable credit rating you should be able to get a personal loan without having to give any specific reason for the loan. They will certainly require you to be UK resident at the time of the loan application, but they're unlikely to require that you remain UK resident in the future.

Borrow money to move abroad


How many short stories make a collection

Question: I would like to know, from someone who has marketed a collection of short stories (or is otherwise knowledgeable in these affairs), about how many short stories a publisher is looking for to constitute a collection. Let's assume all the short stories are between two and ten pages long.
Comment: Enough to fill a book.
Comment: However big the publisher will offer a contract for.
Comment: I assume you have short story collections. Why not count 'em up?
Comment: How big of a book?
Comment: Generally, the publishers want a certain page count.  You need enough stories to reach that page count.
Answer: I think the thumb rule is 40,000 words totally. The reader who buys your collection will feel he/she has got his/her money's worth if there are at least 40,000 words to read. At an average of 2500 words per story, that makes 16 stories. Less no. of stories if they are longer.
Hope that helps.
Comment: A novella really cuts down the number of stories. I see that a lot in collections, one story will be a novella.
Answer: My rule of thumb: Publish when the paperback is thick enough to put a readable title on the spine.
I use CreateSpace for my paperbacks. For CreateSpace, you need a minimum of 110 pages to put text on the spine. That gives 1/8" of room for the title. That's maybe an 11 or 12 point font (assuming all caps or small caps with no descenders), which is pretty darned small.
So I figure a minimum of 130 pages total, including frontmatter and backmatter.
The amount of text you need depends on a bunch of parameters that affect page count: trim size, font, font size, leading (aka line spacing), margins, paragraph length, amount of frontmatter and backmatter.
I know numerous writers (including me) who publish collections with 5 stories. My one collection (so far) has 27000 words, including 24000 words of story content, an introduction for the collection, and 300–500 of author notes for each story.
Answer: Short story collections are notoriously had to place over the transom. Typically a writer will have published most or all of the stories in other venues and then work with an agent to market the collection...at which point the length will vary widely depending on the publisher.
At any rate, there's really no rule of thumb due to the differences between publishers. Do you have publishers in mind? Have you published any of the stories in publications that are likely to be of interest to a publisher?
Comment: I think you're going to have to consider the number of stories as a function of the publisher you find. There's no real average to be had. Publishing your stories individually will hopefully open the doors to publishers willing to print a collection. I'd package up your collection with the stories you feel necessary and then, when you work with the publisher, discuss including more. Sorry I can't be more helpful, but it is such an individualized process.
Comment: I have published three stories (of ten) with different, small publishers. None of these houses have published anything beyond a magazine in the past. I'm seeing more and more small, indy publishers publishing collections, but I haven't gotten my hands on many to see what's average for number of stories. Obviously, a complete collection is a complete collection, but I feel like I have a few stories that could be added or removed to maintain the integrity of the collection.
Answer: I'm in the UK but I've had my first short story collection published at the tail end of 2018 by an American publisher who had previously published academic publications, but was interested in branching out with my collection of fictional stories, which are all cello based, including a lot of historical research.
I aimed for between 40 and 45,000 words, and provided illustrations for all the stories, and it was published as I submitted it, already proofread and with a list of illustration attributions and permissions.
As I was writing in a field that also is difficult to place I feel very lucky to have found the right publisher for that collection. I have no agent at present, but joined the Society of Authors who give useful advice on contracts.
Comment: Welcome to Writing.SE! While an interesting anecdote, I'm afraid I don't see an actual answer to the question here. How many short stories were in your collection?
Comment: I like the specific word-count, but maybe if this is broken into paragraphs, that part of the answer would stand out more.  Also, I agree with @F1Krazy - do you recall how many specific stories it was?
Comment: Welcome to Writing.SE Gill.  We'd love to see more answers (and/or questions) from you in the future.   We like to see more fleshed out answers here as a general rule.  I am guessing your point is that the number of stories doesn't really matter, that it depends on the word count.  That's a great point (and a bit of a frame challenge for the question, which is totally allowed).  Perhaps you could state it more directly?  Or be clear about your point if it's actually something else.  Thanks!
Answer: Go into a bookstore and look at a variety of shortstory collections, both by a single writer and anthologies. These are works that have successfully been published. Note the number of pages and the number of stories in each volume. Then do your calculations.


Is filling up the empty space in a disk with any data enough measure against file recovery

Question: If I have an important data in a disk (flash, SSD or HDD) and I deleted them, I know it is easy to recover these deleted data (even by using free software like recuva. Now if I fill this disk with any data, let's say a large movie file or so until the disk has no more empty space then deleting these dummy files again, will this be enough measure to stop people from recovering the deleted files? isn't that a rewrite?
Comment: Although not a complete answer, this post may be of use: http://security.stackexchange.com/questions/20270/software-that-encrypts-the-data-before-deleting-it/20274#20274
Answer: This is enough, or not, depending on the disk technology, the budget of the attacker, and some other details.
When you fill a disk with zeros, you force the filesystem to reuse free blocks, and rewrite them. So, as first order approximation, this looks good for you: your file contents are overwritten. However, there are details:

On some operating systems and filesystem, filling the disk completely is a reserved privilege. Typically, on Unix-like OS, the last 5% of the disk are reserved for the root user. So do the filling as root.
Some filesystems do tail-merging: a file uses blocks of a given size (say, 4096 bytes), but the last block of a file is often not completely filled. Most filesystems just keep that unused space, but some strive to optimize the space allocation and will regroup the "tails" from several files into a single block. The consequence, here, is that "filling up" the disk with a big file full of zeros may fail to reclaim all free "tail space" (because a big file full of zeros is still one file, with a single tail). The final bytes of your file may thus avoid overwriting.
There is a neverending debate about whether old data may be recovered from an hard disk even after being overwritten. The short answer is: "probably not for a modern magnetic hard disk, plausibly yes (partially) for SSD". See this question and also that one. But such recovery will entail some non-trivial costs (opening the disk in a clean room, hooking extra circuitry...) so rational attackers will do it only if the data is worth it.

If the confidentiality of the data you want to wipe out is valuable, then the cautious course of action is to physically destroy the storage device (shredding, melting, degaussing,... there are several possibilities, with various degrees of efficiency, price and fun). If your data secrecy is not worth the 100$ for a new disk, then you can probably do a simple fill-up of the disk with dummy files: low-value data implies cheap, unmotivated attackers.
Next time use disk encryption. If data never makes it unencrypted to the disk, then wiping the data out is as simple as forgetting the key. This abstracts away physical details of the disk.
Comment: To clarify your suggestions, is sudo not sufficient to perform the write or does it always have to be root? Secondly, the point regarding tail-merging isn't clear to me. Why would a block of file not be completely filled? Secondly, what is the definition of big file with zeros? How does this differ to /dev/zero,/dev/urandom or /dev/random?
Comment: For a HDD/SDD that is entirely overwritten with 0x00 bytes once, recovering data through regular interface like IDE/SATA/NVME using any software is not possible, and one will have to open the housing and access the HDD flatter or SSD chip directly, right? If I want to prevent a curious layman second-hand buyer from recovering my files using common recovery software, isn't filling with 0x00, enough?
Comment: @DamnVegetables: It is, but make sure you use a low-level tool to write the whole _device_ (not just a file or partition), so it also erases MBR, partition tables, filesystems, etc. Example: `dd if=/dev/zero of=/dev/sdx` (not `/dev/sdx1` or `/path/xxx`)
Answer: When you are using a HDD; writing filling it all up over and over again and changing file format and operating system and than filling it up over and over would help you.
It is actually said that changing the OS and changing the file format (NFST to FAT32 etc) makes revocery pretty hard. And if you fill it up with newer data and do these practices in a loop, there is chance that nothing will be found on the harddisk.
Some also say that using small files may work better because all the headers will get messed up and stuff.
However, this is almost impossible to do with SSDs. This is not %100 correct but to explain it very simply think it this way;
SSD's are storing voltage rates to determine ones and zeros. However, it does it in layers. When you write and read as a end user you write to top layer... But, previous layers are still there and they are accessible by special machines.  (you can find various papers about it  here is one )
and fun fact: you know super magnets that are used to carry the cars and such... They can clean up your HDD's.
Answer: No. Adding 0s to the hard drive is easily recoverable (with a special machine). It is not
If you really want to reuse a hard drive in a safe way I recommend you using the "shred" utility in linux or any other similar utility.
Let's say that simply writing once over a hard disk is not enough to make the hard drive truly forget about the data that was here.
You don't really need to use "shred" you can use "dd" and add data from the "/dev/random" or similar. But you will need to do this process several times to be sure there is not information from previous data.

Edit: using large files as movies to fill the hard drive should be fine as long as you do that with several large files (not always the same), and fillint it several times, but adding random data would be better. FBI recommends at least filling the drive 7 times.
Comment: But that is when a hacker or the law-enforcement try to recover the disk, and it should not be recoverable by an average user, who would not open the HDD housing, with a common recovery utility like Recuva, right? I only try to prevent a second-hand buyer from recovering my deleted files, by filling the entire empty disk space with "0x00" bytes.


How did Jor-El stand a chance against Zod?

Question: In Man of Steel, it was made clear that Zod was born to be a great warrior, while Jor-El was the planet's foremost scientist.  How then did Jor-El completely demolish Zod in hand-to-hand combat in the opening sequence during the birth of Kal-El?
Comment: =/ I think you're looking at this too much like a fan. Jor-el quite easily bested Zod when they were fighting, Zod could've blocked if he's that superior. If he was so desperate to stop the launch wouldn't the thing to do, especially for a military man, be to quickly get past the one you're fighting and get to your objective. Why would Zod not want to defeat Jor-el without killing him to in his mind save krypton? Also..Zod blind side stabbed Jor-el when he was looking up at the launch..hardly a skillful kill. It's just a bit far-fetched and could have been done better. Seemingly they simply wa
Comment: @user6472 what is `wa`?
Answer: Just because Jor-El was a nerd doesn't mean he is a weakling. Jor-El is a skilled fighter and pilot in the comics.
It doesn't matter what skills they possess, because in that scene you can see that Zod was surprised to see Jor-El do something so drastic. Zod was naive, in my opinion, even until the climax. He actually thought Kal-El would somehow give up on the earthlings. He says during the climax fights that his entire race is all gone, quite emotionally.
My point is, when he sees that Jor-El is ready to go the distance, he is surprised and that's when Jor-El gets him - while Zod is off-balance. He wouldn't be able to do that in an open situation, granted.
And what about the other scene when Jor-El escaped while being captive. He takes three guys using only a flash as the distraction. Jor-El is pretty bad-ass and this scene was kept for a reason - to clear your specific doubt. Jor-El was very skilled at fighting but not as good as Zod.
I don't agree with you, he did not completely demolish Zod. Zod was just down for a minute and the launch was done. It was unfair really. Two against one. One working the launch and one fighting Zod.
Comment: YouTube link is dead...
Comment: Not to mention the fact that Jor-El was fighting to save his son's life...
Answer: Agreed, Zod was born and raised to be a warrior. While Jor-El was an intellectual. No matter what one is born to be, a drastic situation creates a warrior out of every being. Jor-El required drastic measures to evade capture and fight the general. While Zod was reluctant and more focused on the retrieval of the codex. He had respect for Jor-El and did not want to defeat or kill him. His purpose was to try and persuade Jor-El to agree with his vision. At the end, when the codex was sent to Earth, Zod finally killed Jor-El. Just because Zod was beaten a few times, it does not make him weak. Zod could easily have sent a few soldiers to retrieve, or taken some support with him. But he went in alone knowing the risk and the requirement of the situation for some tact.
Answer: Jor-El is a military scientist most likely and Jor-El in Superman: The Animated Series also kicked a fair amount of ass.
Answer: Someone needs to learn something new. Zod stabbed Jor-El in the stomach, but a few seconds later, he was launched skin dead into POD to the earth. Zod did only dismantled him a little. In a small village on earth, Kal el gets there as a superhuman. It is the good friend of Zod who killed him before he gets his superpowers activated on earth. Kal el wants to save his father. But since Jor-El forbids himself to get forever life he dies in his son's bloody arms. But his mother survives so thas something else. Yeiii?
In other series and movies, Kal El kills all bad before they get superhuman. Jor-el said they must wear power armors to take the sun down into a red giant. And after Kal El gets sent to death by a blue knife in the stomach all over again like his father was stabbed on his home planet before he leaves. Zod gets drowned into red chamber and Kal El kills Zod and his son easily. Kal El turns on a fake red light and Zod goes inside and thinks Kal El has lost his powers. He says kneel for Zod. But Kal El holds his hand and say no and then banish him to bottom of fortress. Zod has not learned all about how the fortress work and so on.
(Some words can be hard to write down in US English language so bear with me.)

Smallville 9x07 Clark interrogates Tess / Jor-El dies in Clark's arms

Smallville 9x09 - Pandora - Clark vs Zod / Lois uses the Legion ring
Comment: Your answer has many grammar and spelling errors making it hard to read. I have tried to fix it, but check if this looks good.
Comment: What means `launched skin dead` and `It is the good friend of Zod who killed him `? Who is launched dead and I don't remember any friend of Zod who kills anybody?
Answer: In one scene they leave pretty clear that they where mates, probably in the army, he even had a tactical body armour. By the way he fights against Zod is clear he had military combat training, Zod probably are like many other superior officers who are bad at hand to hand combat training, and rely a lot in weapons.
Comment: This all sounds like opinion as opposed to answer. You are saying he clearly had military combat training as if you know what that is like on that planet. Can you at least reference or describe the "one scene" you mention? I suggest checking out the [Tour](http://movies.stackexchange.com/tour) to get a better idea of how to ask and answer questions. We're not a typical discussion forum. *Don't be discouraged, we were all new here at some point.* (PS- taking the Tour will get you your first badge.)


FaxCOmExlib and IIS 7

Question: I have a small web service, which should send faxes. The code for this web service is working fine when it is not in the wwwroot folder. However, once I add this service to the IIS,
I always get FaxDocument exception when I call that service.
I think the problem is in the permissions somewhere.
Can anyone suggest how can I configure my web service to use the FaxComExLib library?
What permissions should I set?
Answer: I don't think I'm familiar with this exception, but there is a page documenting commmon FAXCOMEXLib problems and solutions by InterFax:
http://www.interfax.net/en/dev/faxcomexlib
This page assembles solutions from major technical Web fourms and includes links to the discussions). It might include some info that will help you with the permissions issue.

FaxCOmExlib and IIS 7


Maximal thrust from water pump

Question: For a small water pump like this one here, how can I roughly estimate how much thrust it would deliver considering the maximal pressure (PSI) and the flow rate (L/min). As a nozzle let's assume it is just a tube with a diameter d. I am a little bit confused because pressure and flow rate probably depend on each other as well as on the nozzle diameter.
Answer: This would be a very rough estimation.
$$P = F v$$
Now you assume that the pumps efficiency $\eta$ is 1.
And for the power we assume 2.7 A x 12 V = 32.4 W.
For the flow rate you assume $4.3 \mathrm{\frac{L}{min}} = 7,16 \cdot 10^{-5} \mathrm{\frac{m^3}{s}}$.
This is due to the fact that flow rate and pressure are linked, as you already pointed out.

You see that the lower the pump head, for example the height the fluid has to overcome, the lower the flow rate. So I assumed the specified flow rate is specified for a 0 m head. Typically you would have diagrams that indicate at which pressure heads which flow rates could be achieved. In some / most cases the manufacturers of cheap pumps state $\dot{Q}$ for the lowest pressure head and $p$ for the lowest flow rate.
With the diameter of 10 mm the equations yield
$$32,4 \: W = F \cdot \frac{\dot{Q}}{A} =  F \cdot \frac{7,16 \cdot 10^{-5} \mathrm{\frac{m^3}{s}}}{0,005^2 \pi \:\mathrm{m^2}}$$
$$F = 35,54 \: N$$
This would be the highest possible thrust that pump could achieve. Considering that all assumptions we made were to maximize the thrust it will be much lower in reality.
Comment: doesn't the tube diameter affect the flow rate and the pressure? Otherwise I would just keep making it smaller and smaller increasing the exit speed and the produced thrust, but I guess at some point the pump will reach the maximal 35psi if I my understanding is correct. But I am still confused now, in your equation having a thinner tube/nozzle leads to a smaller thrust, does that make sense?
Comment: In the specs there is diameter of 10mm given. So that's what I used. If you use the continuity equation v1A1=v2A2 you see that for smaller the exit velocity increases. However since $vA=\dot{V}$ you see that the flow rate is not affected since it's constant. Your pump will reach 35psi at the lowest flow rate. Look at the diagram, you would need those to get information about the pump. Otherwise you would just assume that both values are the max. possible values as I did.
Comment: So a smaller area (using a nozzle) should result in a higher speed, which normally results in more thrust. In your equation the opposite happens and F gets smaller.
Comment: If I'm not mistaken this is correct. Since your P is fixed. I should add to my answer that I assumed the pump behaves like jet engine and the exit velocity is the speed at which the pump "travels". When I'm not mobile anymore I'll add this to my answer. This is a very rough estimation though.
Answer: Firstly in the link you've provided it isn't clear whether the pressure is 351 psi or 35 psi. In the description it says 35 psi and in the images it looks like this too, but in the title it states 351 psi. I think it may be 35 psi as stated here.
The thrust force of something like a nozzle or rocket is derived from the fact that force is the change in momentum over time. The general thrust equation of a fluid stream jet is:
$F = \dot{m_e}V_e + (P_e - P_a)A_e$
where:
$\dot{m_e} = \text{mass flow rate exiting the nozzle (kg/s)} \Rightarrow 4.3 \text{ L/min} = 0.07167 \text{ kg/s} $
$\dot{V_e} = \text{velocity of stream exiting the nozzle (m/s)} = \text{??}$
$P_e = \text{pressure of fluid exiting the nozzle (N/m$^2$ or Pa)} = 35 \text{ psi}= 241.3 \text { kPa}$
$P_a = \text{atmospheric pressure (N/m$^2$ or Pa)} = 101.3 \text{ kPa}$
$A_e = \text{area of outlet (m$^2$)} = \dfrac{\pi d^2}{4}$
If you wanted to get a pretty accurate result, the only piece of information missing is the velocity of the exit stream, as well as the diameter of the nozzle, which you may be able to get from the manufacturer.
For instance say $d = 10 \text{ mm}$ and $V_e = 3 \text{ m/s}$ then:
$F = \dot{m_e}V_e + (P_e - P_a)A_e$
$F = (0.07167)(3) + (241,300 - 101,300)\dfrac{\pi(0.01^2)}{4}$
$F = 0.215 + 11$
$F = 11.215 \text{ N}$
As you can see the first term $\dot{m_e}V_e$ looks like it contributes a negligible amount to the force - so we can probably ignore $V_e$ anyways as it is mostly the pressure difference between the nozzle outlet and atmosphere contributing to the force. So provided you can find $d$ of the nozzle outlet then you could get a pretty decent approximation!
Comment: That is actually my problem, the exit velocity. It can be increased by making the tube thinner and thinner but then the pressure is not constant, and that would probably affect the flow rate as well. I don't see which equation describes the relation between those.
Comment: @Mehdi The pump has a set flow rate, pressure and outlet area. Given this info the thrust force can be calculated. The flow rate will NOT change if the diameter is changed but rather the velocity will.
Answer: This is best done by doing a momentum balance instead of trying to calculate pressure.
For a first order estimate, use the flow rate and the nozzle crossection area to compute the exit speed of the water.  This is the momentum of the ejected water per unit mass.  This divided by the time per ejection of each unit mass (which you get from the flow rate) is the force.
Force = momentum / time = mass * speed / time

Maximal thrust from water pump


Mount a fully articulated tv mount with only one stud

Question: Here is my issue. In my house I have a recessed area that perfectly fits my 60" LED TV, the issue is that the stud I would use to mount is directly center of the recess and radiates 16" On either side so a typical mount won't reach the other studs. I want to use a fully articulating wall mount so that the tv is mounted to the wall but also can be pulled out so not hidden inside the wall recess. Can I use a toggle anchor to bolt the ends of a mount into the drywall and then bolt the middle of the mount to the center stud? Thoughts, tips, suggestions?
Answer: Your best bet to assure that the fully articulated TV mount is secure and will operate correctly is to mount a large piece of 3/4" thick plywood across the wall in the back of the recessed area. Make sure this plywood spans across at least the three studs in the wall and even better if you put it full width and pickup the corner studs as well. Screw the plywood to the studs with heavy duty screws at least 3 or 4 per stud. The plywood can be sanded, primed and painted to match the wall. Behind the TV you will barely see it there, but when you do you will reset assured that you have the best secure mount possible.
Trying to use toggle bolts into just drywall is not a secure proposition. Fully articulated mounts can put a huge amount of torque on the TV bracket when extended and pulled out. This can rip the toggle bolts right out of the drywall. Use the thick plywood as described above and distribute the forces of the bracket torque across a significant portion of the wall structure. And by the way, plywood has fantastic screw holding strength when used with proper sized pilot drilling.
Comment: +1 on this. Drywall bolts are a wonderful thing, but the problem with TV mounts is torque force, not the shearing forces of (say) hanging a heavy picture frame. Screws and a flat plane of wood distribute the torque force perfectly.
Comment: Can either of you provide more insight into the torque force described here? I'm having a hard time getting relevant search results and want to make sure my own TV mount is properly built (that is, overly so, not under). I'm using the plywood method to span studs but want to make sure I've over-built and that I'm not going to lose a screw _head_, causing the system to fail. I may end up posting my own question, if needed.
Comment: @TylerForsythe - Best idea is to describe what you are doing in a new question. Comments can go away.
Answer: I would (personally) cut the drywall in the recess in question and toe in a 2x4 or two between the studs so that you have a solid plane to work with.
While you could use the right weight bearing mount on drywall, your application would serve better being mounted directly to wood.
If the recess is deep enough, you could use a 1x4 or even a sheet of plywood and mount to that without cutting the drywall.
It all depends on the depth you need, and how much you care about what it looks like behind the television.
Of course, replace the drywall when you are done and patch it in and paint it, if that is the route you go.


How to detect when files from my USB were copied to another PC?

Question: I accidentally gave my USB to my friend and then I realized it had some important files of mine. Is there any way I can know if he got something from the USB?
Comment: If he's a **friend** can you go analog and just ask him?
Comment: @HarrySattar Just remember it's fairly toxic to assume your friends will lie to your face.  This is on you.  If your friend had done **absolutely nothing wrong**, you're already assuming he had copied your files and will lie about it, which is, based on current information, a situation you **completely made up**.
Comment: @HarrySattar unless he doesn't deny it. If he says "yes" then you know.
Comment: @HashHazard for sure he will deny
Comment: @Nelson Actually in those files I had my final project. Which he was struggling to create. And I know him he will take advantage of that mistake.Still should I ask him?
Comment: @Kyslik and what if you aim to publish that project as a Product of your startup. I have that project everywhere I could save.
Comment: Quick note in case this gets thrown over to Interpersonal.SE from @tudor's comment. We don't accept "What should I do?" questions over there, so "Should I ask him?" would likely get closed. That being said, "How can I ask a friend if he copied some sensitive information when I lent him my USB?" would fit right in.
Comment: Some applications routinely store the user's name, etc. in the document properties.  If your files include that, your friend may not know to look.  If he copies your work, makes some content changes, and claims the files are his own work, you'd still be able to see properties when you look.  This approach relies on lots of assumptions ...
Answer: No logs are recorded on the USB itself around file accesses. At best, you might know if the files were changed by looking at the file timestamps, which can sometimes happen just by opening them, depending on the program opening them.
But there will be no way to determine, by looking at the USB, if the files were copied.
Comment: @DavidFoerster assuming, more importantly, that the friend didn't have the foresight of mounting the drive read-only.
Comment: @DavidFoerster hence the "at best". And even I had to look it up since you mentioned it, so I'm not sure that "trivial" can equate to "likely".
Comment: This assumes that your friend didn't reset the access time stamp afterwards which is trivial if you care about it.
Comment: I'd suggest adding to this answer: *do not attempt to view access timestamps using Explorer*.  Just opening the folder containing the files with Explorer can cause it to read the files in order to produce a preview image, thus losing the access time information.  Use a command prompt and `dir /ta` to get the information.  But as pointed out by TobySpeight below, FAT filesystems (which is almost certainly what's on the device) don't track update times anyway, so the information almost certainly doesn't exist.
Comment: There will be timestamps in the metadata of the files (right click and choose "Properties" or choose the "Details" view in File Explorer). Those other file activities you ask about are not recorded in Windows file systems.
Comment: @Jules but that also means that the friend could just have opened the device in explorer in order to put something on there, so the changed access timestamps do not prove that anything was copied.
Comment: Testing a USB stick here on Windows 7, I can see a *date*, but not a time for "accessed" under file properties (unlike a local disk or network share, where "accessed" has a time as well. But previews can set the accessed time anyway.
Comment: Also note that there are registry settings in Windows (and options that can be set under Linux) that disable updating of access timestamps, so they absolutely cannot be relied upon.
Comment: No timestamps are there. Can I get the history what folders were opened and when??
Comment: My comment was less of a criticism of your answer and more of a clarification for OP and other readers. :-) Triviality is often in the eye of the beholder. My maths professor would often call omitted parts of a solution "trivial" meaning "you may need to look it up but you should have little trouble understanding this part".
Answer: There is no way to be sure by strictly technical means.
On the one hand, if your friend has antivirus software installed, it would probably scan your USB stick as soon as it was plugged in their machine; and this would be completely indistinguishable from data being read as a part of copy operation.
On another hand, if they would like to cover their tracks, there are many ways to reset the timestamps, and to prevent their change in the first place.
So... ask them? Get access to their machine and check for the copies your files (if they agree)? Tell them that your data was sensitive and kindly ask to delete it if they accidentally copied it? These might be the questions for Interpersonal and Law SE's; security-wise, your data are already compromised.
Answer: It depends on what kind of filesystem is on the disk.  Most filesystems retain an access time that can be viewed with ls -lu, provided the "friend" mounted the filesystem read/write.  (Note: apparently Windows OSes have no equivalent to ls -lu, so this won't be useful if that's what you have).
If the "friend" mounted the filesystem read-only (or with noatime or similar options), or the disk has a filesystem that doesn't store access times (notably FAT and derivatives), or he covered his tracks by using utime() after reading, then you won't see this evidence.
Alternatively, you might get a "false positive" if something on his system read the file autonomously (e.g. for generating summaries, or looking for malware), but he didn't see the contents or copy the files.
In the end, what little information that is recorded on the media tells you very little about whether the information was accessed, and if so, how it was accessed.
Comment: The Windows equivalent of `ls -lu` is `dir /ta`, although it is somewhat less likely to be useful due to the prepensity of various Windows software (including Explorer) to automatically open and scan any files of types that it recognizes in order to show previews, along with the fact that many users install "tweak" software that often recommends disabling access time updates for performance reasons.  Also, as Windows by default formats removable storage devices as FAT, the information is not likely to be present in any case, unless OP intentionally formatted the device as NTFS.
Comment: TBH, it really hadn't occurred to me that it might have been in a Windows environment when I read the question.  If it had even suggested that, I wouldn't have bothered answering.
Comment: If you know what the Windows equivalent of `ls -lu` is, then please edit it in.  As I know nothing about Windows, I'm not qualified to do so.  I'm not even sure that Windows can actually mount any filesystems other than its native ones (and possibly ISO 9660?  But that doesn't record access times either, for obvious reasons).
Comment: Also I am probably not the only one, who have in fstab set noatime for all media (for elimination of writing timestamps repeatedly, when I do not use prorams, that rely on them - mutt and like)
Answer: You could try dir /T:A and compare with dir /T:C
/T TimeField    Specify the time field displayed
and used for sorting. TimeField may be any of the
following letters.

  C : Creation time.
  A : Last access time.
  W : Last write time.

For instance, when you use the option "/T:C," the
time listed is when the file was created.

Refer: https://www.computerhope.com/dirhlp.htm
Answer: By default, there will be no record of such activity.
When a file is accessed or changed, either the OS or the application can update its "last write" or "last access" property.
Per Microsoft's documentation:

NTFS also permits last access time updates to be disabled. Last access
  time is not updated on NTFS volumes by default.

Your friend could copy any file(s), and I would not expect the "last access" date to change.
In addition, any auditing for failed/successful attempts to access files would be recorded in the Security log on his computer.
An Inconclusive Method
The only other method is checking for foreign SIDs on file/folder ACLs. If you look at the permissions on a file (on the Security tab), unresolved SIDs may appear.
Unresolved SIDs appear as long strings, such as S-1-5-21-3624371015-3360199248-30038020-3220, rather than human-readable names like SYSTEM, Network Service, or JohnSmith.
Note that foreign SIDs will only be added if he took ownership of files or modified permissions, so the absence of such SIDs does not indicate a lack of access.
Comment: This is the correct answer. Even if the pendrive uses NTFS (unlikely), last access times are not updated by default since Vista.
Comment: @kinokijuf Right, and even if they *were* updated, it doesn't mean that the files were copied, it just means they were accessed, for example opened for viewing.


Why are Ghouls worried all people from Tokyo become Ghouls?

Question: In Tokyo Ghoul:re 2 , episode 11, Ghouls from the group of Kaneki like Nishiki were worried all people from Tokyo becomes Ghoul. Why is this so? Why if you are a Ghoul are you going to be worried other people becomes like you?
Answer: During the last arc all investigators, as well as ghouls society, were joined together to defeat the main villain. During that time everyone were convinced by Kaneki that ghouls and humans should leave in the same place happily without harming each other.
So from the above explanation, you may have noticed that the Goat organization created by kaneki has one and only single policy to protect others as well as humans.
It's fairly straightforward that goat does not want more ghouls to be hunted by CCG and so to happen that, they were afraid of all humans becoming ghouls and more severe hunting would be there and CCG will not cooperate with them for sure.
Answer: From what I understand, I see two reasons:

Goat and CCG are both working together on the last arc. Similar to what @ani's answer mentions, Goat was not an anti-human organization but rather, an organization aimed in finding ways for humans and ghouls to co-exist. It would be against their purpose if members would want for all humans to become ghouls.
It would affect their food supply. Ghouls feed on humans. If humans would continue to become ghouls, their food supply would drop. Sure, they can cannibalize but from what is seen in the manga, ghouls do not taste as good as humans or half-ghouls.


Identify an Online Puzzle: Website Based Puzzle

Question: Around 2007-2009, I was introduced to a website which hid puzzle clues in website data such as picture code as well as normal puzzles using various different types of code breaking and cyphers.  The goal was to find the next url to progress with the puzzle.  The puzzle eventually ended as the site was not being updated and it even had a forum for help along the way.  Any ideas on what the site was and if it still exists?
Comment: There are too many websites of that variety to name. Notpron, Tricky's Riddles, and ze?t are three that I've personally played.
Comment: Do you remember anything else about the puzzle site? What it looked like, what the challenges were about...? (I ask, because there are several possibilities in my mind, and additional details help.)
Comment: It was primarily images with puzzles either in the image itself or hidden in the code of the page or the image code.  The main .com url was always consistent but the page name after the slash was determined by the puzzle answer for each step.
Comment: [The Python Challenge](http://www.pythonchallenge.com/about.php) is a fairly early example of this sort of site (the domain was registered in 2005 according to WHOIS). Although it doesn't sound exactly like what you're describing...
Comment: @JoeZ. I think it's too broad.
Answer: The riddle series you were looking for was Tricky's Riddles. It's an old puzzler that I myself came across in 2006 back when a bunch of my middle-school friends introduced me to it, and back when it didn't have a domain and was still being hosted in a University of Exeter home directory. Looking back at it, the riddles were really shoddy and much too "random", but back then it was the ultimate challenge for us.
However, there are quite a few more riddle pages that fit that description, including Notpron and ze?t, out of the ones I've personally played and failed at (ze?t appears to be down at the moment).
Comment: Menawhile, if you like website-based puzzles, I'll plug mine: [The Temple of Quetzalcoatl](http://joezeng.com/quetzalcoatl/). So far it has 19 levels, but nobody who's tried it has gotten past level 17 yet.
Comment: Can we take this conversation to chat?
Comment: Although it seems that could be the right site, Dracula's Riddle is another one that was very well-known in terms play length with an appropriate learning curve.
Comment: @Chrismas007 We can take it to an IRC chatroom, but I don't like talking about ToQ in Stack Exchange chat rooms because those are publicly logged.
Comment: @JoeZ. Sounds good let me know.
Comment: Notpron was the one I played back in the day.


Can an Ethereum contract be updated without having to be re-submitted?

Question: I am wondering - can an Ethereum contract be updated without having to be re-submitted? Say, if I find a bug in my contract, can I fix it without having to create a new contract and making my potential users have to update their references? As I understand, I can always upload a new contract and make that contract fetch the old data plus possibly invalidate the old contract, but that still doesn't let me redirect anyone using the old contract into the new one.
Answer: You can separate concerns - have a contract that the users interface with and that has a reference (an address) of another contract that contains the actual logic. Then, you can control the interface contract and update it with the address of the logic contract on updates.
Answer: No you cannot. A nice way to mimic mutability is via name registration. You can register a name which you distribute to users or use in dapps and other contracts. Whenever you update you update your entry to point to your current contract address.


Can I use anything other than Photoshop for my needs?

Question: I have been using Photoshop (I believe 7) for what seems like forever on Windows 7 and my Photoshop was a pirated copy.
However my computer crashed and I have acquired a new one with Windows 10. Now I am not sure wether or not to splurge on Photoshop or if something free will serve me just fine.
What I use in Photoshop are the following:

Layers.
Magic Wand Tool (with different tolerance).
Selection tools (the lasso).
Dodge, Burn.
Brushes (mainly pixel soft and hard, in different sizes).
Zoom in to pixels.
Colour correction (saturation especially).
Cut and Paste.
Resizing selected areas and pasted pieces.
Text tool (sometimes with layer effect, but this is not a need).
Rotate items, and mirror items.
Directly scan my hand drawn artwork and whiten the background, correct colours etc.
Make images ready for printing at high resolution (300ppi or higher. My scanner actually does 1200ppi).
I save work in PSD when I work on them due to layers etc.
Save finished work as JPG.

Will anything other than Photoshop do for me? I cant really afford that software now.
I do not use it for photo editing, it's more for "scrap booking" really. Cut and paste from images onto blank canvas (usually international A4 or A5), as well as editing hand drawn images.
Answer: it sounds like Gimp would have everything you need.
Comment: Ive read that the swich is hard when your used to PS.... but seems like I must give it a try :D


What is the difference between 傻瓜 and 笨蛋?

Question: May sound like a silly question, but is there a difference between 傻瓜 and 笨蛋?
Comment: Quite subtle. Most cases of 笨蛋 are in derogatory sense, while 傻瓜 **sometimes** could bear some complex subjective feeling: the emphasis may be not on "silly", but other commendatory characteristics. For example, the movie "3 Idiots" is translated to "三个傻瓜", readers will probably think, "they are not really silly".
Comment: if you add a 大 or 小 to them, 大笨蛋, 小傻瓜, the meaning would be changed, like you buy an expensive ring to your girl friend, her may call you 大笨蛋.
Answer: Literally 笨蛋 and 傻瓜 mean stupid and silly respectively. I would say, as a native speaker,  笨蛋 is used as a negative adjective for others while 傻瓜 is more teasing especially for the the speakers themselves. Also, it depends on the status of the speaker and listener, for example, we will call the kids 笨蛋, but call the wife 傻瓜 when they make the same mistake.