What are the rules for plasmid names?

Question: What are best practices for naming newly created plasmids?
For example, a common format is pABC123. What is the exact specification? Must there be 3 letters?
What databases of plasmid names exist? How much care is taken to avoid name collisions?
Answer: So there are no rules per say (although I wish there were). But there are commonalities among plasmid names and they can help people identify them:
Include the empty backbone name in your plasmid name. This simple piece of information can often convey many important details. Once you know the backbone a plasmid is based on, you can usually derive: a) the bacterial antibiotic resistance, b) the promoter that drives the insert, and c) any other selection markers (for use in other cell types, e.g. eukaryotic cells).
Include information about the insert in your plasmid name. This is often a 3-6 letter representation of the gene (or DNA sequence).
Often researchers will add a lower case letter to the beginning of their insert abbreviation to specify what species it is. Example: 'h' is for Human (homo sapiens), 'm' is for mouse (mus musculus), 'r' is for rat (rattus rattus or rattus norvegicus), etc.
Add any tags or fusions that are on your insert. Typically you would list any tag or fusion protein in the order they appear in the plasmid and their relative position to the insert. Example, if you have a Flag tag on the N-terminal of your insert, you would list it first.
e.g.   pBACKBONE-Flag-hGene
If there was also an EGFP fused to the C-terminal of your insert you would list it after the insert.
pBACKBONE-Flag-hGene-EGFP
If your insert contains a mutation or modifcation, this should be included in the plasmid name.  Mutations are generally listed as the amino acid change and not a nucleotide change. The proper way to denote an amino acid mutation is to list the one letter abbreviation of the wild type amino acid immediately followed by its position (number) relative to the start Methionine (Met) followed by the one letter abbreviation of the mutated amino acid currently at that position.
Check for more information at Addgene.com they are the largest plasmid repository in the world.
By collisions I'm guessing you mean naming your plasmid something that is already "taken." This is a benefit of submitting to a repository, they will ensure this doesn't happen.if your planning on filing a patent, your parent attorney will do it.
Answer: One of the most common methods (described by AddGene) is p (for plasmid), followed by the name of the backbone, a dash, and inserts delimited by more dashes. From this we get things like: pBluescript-CMV-mACT1-GFP.
Another method which I prefer is to name all your plasmids in the format given in the question: pABC123. Here ABC is a 3 letter designation that the researcher should consistently use for every plasmid they create (often their initials), and the numbers are sequential (padded with zeros for better sorting by programs).
AddGene is one of the largest plasmid repositories out there. Unfortunately, collisions are a common problem - you should always search the name of a plasmid before assuming things based on the name. While the above two strategies help reduce the odds of collision, there are very few 3 letter combinations that haven't been taken.

What are the rules for plasmid names?


Do I need a transit visa for Denmark in addition to my single entry Schengen area visa?

Question: I am a Chinese national holding a US greencard. I am planning on traveling to the UK and the Schengen area to visit France, Germany, and possibly some countries in between. I am applying for a UK visa and a single entry Schengen visa now. On my journey to the UK I am stopping in Copenhagen for a day. Do I need a transit visa for that? Should I apply for a multiple entry Schengen visa, or is that too much? My guess is a transit visa for Denmark and a separate single entry visa would be easier to apply for.
Comment: @uncovery Not the same situation and not the same question.
Comment: possible duplicate of [Can I travel to Paris for a day with a single entry visa for Schengen from Switzerland?](http://travel.stackexchange.com/questions/14692/can-i-travel-to-paris-for-a-day-with-a-single-entry-visa-for-schengen-from-switz)
Answer: Karlson's anwer is correct in that if you stay 'airside' you do not need a visa. I would however like to point out that since Copenhagen's airport mostly services flights within Schengen, most of the airside area is going to be inaccessible to you. In fact, only a very small part of the airport will be accessible to you without clearing passport control. While I can imagine spending an entire day in Copenhagen's airport, I think I'd go stir-crazy if limited to that small area for more than an hour or two.
Consequently, I'd strongly advice you to obtain (if you can) a visa that allows you a little more leeway. This will then not only open up the rest of the airport, it will enable you to go into Copenhagen, which is just a 20 minutes train ride from the airport.
Comment: I'm not claiming any familiarity with the visa issue. Just pointing out that the international side of CPH airport is very small. I'd hate to be stuck there for an entire day.
Comment: That's a good point. Thanks for the heads up!
Answer: There is nothing that says you have to have a transit visa if you don't leave airside, however, if you do you will need another full fledged Schengen short term visa as Chinese nationals are required to.  You can also review the list of all agreements regarding visa issuance by Denmark.
And if this is not enough you can visit the VFS Global site for China which doesn't provide for a separate transit visa like the one in India for example (though the application does).
Comment: Thanks for your reply! i guess i will have to apply for a multi entry Schengen visa since I am going Denmark-England-France. I have heard that multi-entries for a first time short term traveler is more difficult to obtain than a single entry. What do you think?
Comment: There may be difference for those holding US Green Cards but that's unconfirmed.


What are the construction rules for the 2015 BattleBots reboot?

Question: Do the contestants on the new BattleBots have certain restrictions when it comes to creating their competition robots: for example, a certain budget, size/weight boundary, or material type? Was this addressed in the original BattleBots?
Answer: This information seems to be in the BattleBots Wikipedia article. According to the article, it appears that only the weight of the bot matters:

Robots at BattleBots tournaments were separated into four weight classes. The weight limits increased slightly over time. At the final tournaments the classes were:

Lightweight – 60 pounds (27 kilograms)
Middleweight – 120 pounds (54 kilograms)
Heavyweight – 220 pounds (100 kilograms)
Superheavyweight – 340 pounds (154 kilograms)

Additionally, certain types of robots had "bonuses" that allowed them to enter lower weight classes.

'Walking' robots ('StompBots') propelled by means other than wheels were initially given a 50% weight bonus. The rules changed following the victory of a heavyweight StompBot (Son of Whyachi) at BattleBots 3.0. For BattleBots 4.0 and beyond only a 20% weight bonus was given to walkers and the technical rules specified that walking mechanisms not use cam operated walking mechanisms as they were functionally too similar to wheel operation. Since the rules change, walking robots have entered the competition, but none has achieved any success beyond preliminary rounds.

The official BattleBots website seems to have undergone a recent change, so none of the official rules pages appear to be accessible and the current "rules" page has no actual information on it.
Answer: I asked the BattleBots team through their website. After the incident yesterday with the fishing net and the comment about no ball bearings...
They sent me a short PDF file with the rules for 2015. This differs from the 40 page version of 2009. They also told me that if there was a second season to come, there would be a new set of rules to come out.
My guess is (and this is only my personal opinion) that ABC invited the veterans of the sport to bring back the show, and that the newbies will actually get their chance next season.
My email was the following:

Hello Battlebot Team,
I have been interested in Botfights for the last 15 years.
  I it was always my dream to build a Battlebot, now I think I finally got the resources to build my own.
  I have been searching and can't find the rules for this Tournament, only the ones from 2009.
  The comment about the ball bearings in the last episode scares me. How can a shaft turn without the bearings?
  Could you give me a link to the rules of this season?
  And in case that's not possible,
  Could you please answer me the question why there is such a secret of the rules?
Hans

Their reply:

Hi Hans,
If ABC grants us a second season we will announce all the details for our season 2 tournament: Entry info, Rules, Ticket info, Sponsorship etc. The best way to find out first is to follow us on social media (see links in signature below and/or sign up for the newsletter on our website (www.battlebots.com).
Thanks for your interest - really appreciate it!
Estimates on the next Tournament is May 2016, but could be sooner…
Attached are the Season 1 rules - these will change for season 2, so do NOT start building your bot until the new rules and entry procedures are announced (entry could be via design application, qualifying tournament or both). Also note that these season 1 rules were written for veterans of the sports—people who have competed for over 10 years—people who have a ton of experience building and competing. Since season 2 will attract more newbies, the season 2 rules will be much more comprehensive. Your best bet, while we wait for ABC to green light season 2 (if they do so), is to start designing your robot on paper or CAD.
Finally, read the disclaimer at the bottom of this email. Be safe. And there is no "Secret" to the rules. We're not posting them because they're going to change so much for season 2.
Comment: This is excellent, and answers my concern on why they weren't outlining any rules so far. Would you be able to share the pdf?
Answer: In the original Battlebots, there were a number of different weight classes and weight bonuses were given to walking and shuffling robots, as described in Catija's answer. There were no limitations on size or material choice, other than that it couldn't be toxic or use weapons that would take away from the fights, like nets, liquids, projectiles, and EMP generators. I believe the robots were paid for by the builders, and then they got paid for how well they did or how popular their robot was.
However, for the 2015 reboot, there is only one weight class, which is 250lb, slightly more than the old heavyweight class, and there is no longer any weight bonuses for walkers or shufflers. The builders were given a much shorter time frame to build their robots, only a few weeks, and ABC gave them money specifically to buy materials for the robots, which I have heard from different sources is either $8,000 or $10,000. Other than that, I believe the rules have stayed the same.
Answer: Me and a friend are working on building a battlebot for 2016 when they will hopefully have a new season, but you have me concerned - dot they really choose people then pay them to get stuff and compete?  Because i'm not waiting to get chosen, Im nominating myself, bringing my bot to them and stuff.  Will I not be able to play or what?
And about the rule changes and stuff: it seems there has been a reduction of obstacles on the FightArena thingy.  So that means the bots have to fight better.  I also think there's been changes to the judge's grading system as well.
I also know these little snippets that have probably been rules from the beginning;
Your bot has to have a light indicator that shows when it's on/active (interior or exterior)
Your bot CAN NOT be purchased via eBay, Amazon, hand-purchasing, trading, etc.
Comment: This isn't really an answer to the question. We aren't a normal discussion forum. You might have better luck getting answers to your questions by contacting the BattleBots people directly. Contact info is on their website.


Gastro-intestinal physiology reference

Question: I am a physicist but I have always wanted to understand how my digestion takes place in as much detail as possible. I have no idea about books or reference on the subject of Gastro-intestinal and digestive physiology. Can you help me?
Comment: are you asking about reference of some books based on it?
Comment: If you enjoy physics, Boron and Boulpaep text book of medical physiology is the book for you!
Comment: @agharehanabbas a reference :)
Answer: If you have no medical background at all, you will need a general text that teaches more than just digestive physiology. That is because you need to understand the function of other systems that have an influence over the digestive system (for example, the peripheral nervous system).
Here are a few good general references to get you started:

Physiology by Linda Costanzo, arguably the most synthetic. Extremely good, but I am unsure of its value for someone who has no medical background.
Vander's Human Physiology, arguably the simplest, used in first year of medical school.
Medical Physiology by  Walter F. Boron, arguably the most complex, I would not recommend it as a first try.

You can start by trying to read the digestive physiology chapters, and look up the knowledge you lack in other chapters.

Gastro-intestinal physiology reference


How can I figure out my main character's overall goal?

Question: I'm currently brainstorming a fantasy story, and I love the idea of my main character, but I'm having a hard time pinning down who she is as a person. I know her backstory, her family, her abilities, even her job, but for the life of me I can't figure out what her goal is. I can't figure out what she wants out of her life, and I don't know how to solve my problem. Any suggestions would be super helpful.
Comment: I vote to keep this open, she isn't exactly asking a how to write something but asking how can she figure out a goal for her character.  It is pretty specific and one that isn't opinionated either.  People may differ on how to create character goals but they will generally be different ways to do the same thing.  I think this is a pretty valuable question for writers who build off of a character and not sure how to move on to the next time.
Comment: I think this is a much, much too general question.  Here is the help page that talks about what is on-topic: http://writers.stackexchange.com/help/on-topic
Comment: I suggest you set her aside for now and make a fresh start with a different approach.  Try outlining a plot first and then start fleshing out the stick figures.  See if that gets you unstuck.
Answer: You may not need an overall goal. You may be able to discover this as you write.
Try this: Give her a problem. Any problem will do. She will try to solve it. When she does, arrange for her to fail. And arrange for the failure to make things worse instead of better.
When she tries again, arrange for that to fail, and to make things worse. And so on.
As she struggles with the worsening situation, you will learn more about who she is by the way she tries to solve the problem, and by her reactions to the failures.
Try to arrange for the failures to force her to choose between painful options. Maybe she can have only one of the things she wants, and choosing one means she cannot have the other. Or perhaps she must choose between two terrible options.
As she chooses, you will learn more and more about what she cares about most deeply.
At some point, arrange for things to worsen in a way that relates to her abilities or background or personality. As things get worse because of who she is, she will have to confront who she is in order to make progress. As she learns who she is, you will too.
So you can discover what she wants as you write. You don't necessarily need to know before you begin writing.
Comment: Discovery writing is great.... also think your methods to organically find a goal is great too.  Maybe her character doesn't start out with any goals and her life is just peachy perfect until something comes along to change that.
Comment: This advice is good. Why should a character, or anyone, have a goal? Many of us muddle through life. We do not make things happen. Instead, things happen to us, or around us. That can still be interesting.
Answer: If you don't have a goal for your character... maybe you have made them too perfect?  A common theme to help provide character goals is to demonstrate character growth.  Give them a couple flaws.  Say that she is an elf and a really good magic user, but no one gives her a chance because she is female and she is not assertive enough to challenge people that tell her to go away.  In the end, the goal of the MC is usually the punch line of your story.  It's the lesson learned or will have to be learned in order to achieve the goal.  There may be many side goals or side plots that helps build the main goal, but ultimately, your character is trying to strive to achieve something.  World fame?  Is there an evil person in your story that is trying to do harm? What does the opposition look like?  What is it that they are trying to do to hinder your main character?  If you don't have an antagonist, maybe developing an antagonist's character will help you realize the goal of the MC.
Comment: "Give them a couple flaws." Oh, please, not another girl with daddy issues... the problem with the cliches is that no one is taking them seriously anymore (that's why they are called cliches). Once you declared that you super talented girl has a problem because she is shy, it is clear as day that she will overcome that problem by the end of the book and everything will be peachy. There is nothing more boring than a predictable story arch.
Comment: @ggiaquin - Please put the phone in your trunk while driving.  Listen to music.  Listen to a podcast.
Comment: @Lew  i never said to give them daddy issues lol but it's pretty clear that if she can't find a goal she made the character too perfect because they have it all.  Every character needs flaws it's what creates a balanced and dynamic person.  What ever she decides to actually make as flaws is her choice but the point still stands valid.  I agree predictable is boring.  But so is a perfect character. So please i would appreciate your sass some where else.
Comment: I apologize if I upset you, that was not my intention. No daddy issues, sorry. But for the flaws in general--I must respectfully disagree. The flaws do not make us balanced people, they make us *unbalanced* people---that's why they called flaws. If you meant to say "well-rounded character", that is an entirely different beast, and then it does make sense, everybody has flaws. It is making those flaws the base of the conflict which takes away from the excitement of discovering what happens next because once you show them, it is absolutely clear, that they shall be defeated gloriously.
Comment: @Lew ah yes, well-rounded was my intended thought.  Sorry, the last comment was written while stuck in traffic.  Agree 100% though with what you said.  To some extent though, you can make it where those flaws never get fixed, and the ending that is expected does not happen.  That is reality too.... we all have character flaws as people, we may fix a few but we cannot fix them all.  You can also bait the reader thinking they have it all figured out and then hit them with what wasn't expected.  In the end it's all how the story is presented and key information is given.
Answer: Story is driven by desire and that which stands in the way of achieving desire. If your character had a strong desire, she would have a goal. If she does not have a strong desire, that means she has everything she wants. Or at least she has everything she is willing to work hard to get.
That's fine. Lots of stories start like that. And the answer is simple enough. Take something away from her, or threaten to: home, loved ones, etc. Bingo, now she has a goal: either to save them or to be revenged on those who took them.
Answer: There are some very good answers here, but hopefully the following can work as an addition or substitute to certain elements.
I have a theory (someone else probably thought of it before me) that characters with a personality and traits similar to the writer can be difficult to create goals for. Is your character by any chance similar to or based on yourself to some degree?
I'm sure there are countless scenarios where a character's overall goal can be difficult to figure out, but for this I will focus on the scenario  mentioned above.
If, as @MarkBaker mentions:

"your character has everything she wants"

or as @ggiaquin asks:

"..maybe your character is too perfect?"

I would argue that this character is in her comfort zone. We may not realize that the MC needs something, because she is placed in a context where she does well or is in balance. One way to create or figure out your MC's goal could be to pull her out of said comfort zone.
Sure, this could be forced by some troublesome, threatening or painful experience or treatment which she then needs to act upon, but in my opinion it doesn't have to be that dramatic, unless of course 'dramatic' is what you are going for.
Another way to pull someone out of their comfort zone is to introduce them to something og someone new. She may get a new co-worker that actually asks questions about "the routines" or "how one should behave", she may find that the street behind her house has an abandoned building with something intriguing about it. She may be brought to a friend's party only to realize that she knows no-one and has to mingle within a new social group.
These are just examples off the top of my head, but think of scenarios where you would feel "out of your comfort zone". Maybe introducing your MC to such experiences (based on your understanding of her) may reveal a new goal for her.
A natural progression in the story could then be based on @DaleHartleyEmery's order of "attempts and failures".
Answer: Put aside the character for a moment, and ask yourself how you want the story to end. Then work backwards to your character. If she is, in fact, your main character, she will have, or develop, a goal that is congruent with the story goal.
If you can't do this, maybe you should put your "main character" in a different role, and get another main character. For instance, if your "main character" has everything she wants and all the abilities to get them, maybe you should make her the equivalent of a fairy godmother or good witch of the north (that's perfectly fine), and find yourself a "Cinderella" or a "Dorothy."
Readers see a story through the eyes of a main character. Her success/failure ultimately reflects on the story itself. That's why she needs a goal congruent with the story's goal.
Answer: Thre is no such thing as an overall goal for a person (other than to be happy, blah, blah). Any person, whether a real one or a fictional character, has a slew of simultaneous goals, ranging from making it to the bathroom on a morning after a party the night before to a getting a multi-million government contract for developing a uberdrive for faster-than-light travel (now try to go to that meeting having a pounding hangover headache and land that job).
Our goals change with everything the life and the Universe throw at us time after time.
What you might try is to explore, how your hero would react to a challenging situation. You say you know her abilities? Offer her something which she is not equipped to handle, and see what she does.
She has a job? Fire her.
She has a family? Kill them ruthlessly in a suspicious car crash.
She has magic powers? Fire her, kill her family, and make her drink something on that party the night before, which negates her magic to the point that it might not come back at all.
Then see what happens.
You are the creator and the owner of her Universe. If you want to know what her goals are, you can do whatever you wish to flush them out.
Comment: @MarkBaker thank you for a decency to comment on the downvote—I appreciate that. I might have spoken ambiguously, but I still think, that an overall goal is not something a person would have. If a character lacks personality, it only means that s/he is underdeveloped, and the same can be said for the story, being not life-like, even if it is set in a secondary world. Overall goal is an oversimplication, leading to a formulaic flatline pulp fiction.
Comment: @ggiaquin Yes, the antagonist, of course, whether it is a single-real-mean-villain, the group of crooked criminals, or the disembodied force of forsaken ancient evil magic--literally any challenge, thrown at the main character should shape the goal at hand and eventually, lead to the further development of her character. By the way, could someone tell me what **OP** stands for? My acronym-challenged mind is drawing a blank.
Comment: I like some of the ideas you presented here and is why I suggested the OP create an antagonist first.  Usually if you can't find some "goals" I would go to the opposition and create who would oppose my MC.  If you can't figure out a reason why they would hinder your MC or create ways they could... then there is definitely an issue lol
Comment: OP = Original Poster.  Usually reference to the person who starts the topic or thread of the forum/posts.  In SE terms, it would be the person asking the question.
Comment: -1 "There is no such thing as an overall goal for a person." Well there is all of story theory out the window then! A character is not a person and a story is not life. A protagonist has a main goal in almost every form or story. It is what the story is built around.
Comment: @ggiaquin Thanks! The order in the Universe is restored!
Comment: +1 for the idea that there can be multiple goals, even if the most natural in story telling is for one.
Answer: Use what you (or people you know) wanted. When I had trouble with making a crush for my main character I friended one of my favorite authors on Facebook and asked her how she got the idea of the crush from my favorite trilogy by her and she said that he was based off of her crush from when she was in high school. So think of the main character as yourself or someone you know. It helps immensely.


What happens when all your cards (the whole deck) are in play?

Question: I am particularly fond of going through my entire deck each turn. However while I like to do this, are there any actual rules for handling cases like "You just played a smithy, but there are only two cards in your deck which aren't either in play or in your hand"?
Answer: The rule is always that you do as much as you can of the card, in order.
So, if you play a Smithy, you would draw those two cards.
A case that is more illustrative of how the process works is Lookout. Lookout reads: "+1 Action, Look at the top 3 cards of your deck. Trash one of them. Discard one of them. Put the other one on top of your deck." If you only had two cards remaining in your deck, you would do as much of the card as you can, in order:

+1 Action; no problem.
Look at the top 3 cards of your deck. You only have two, so that's what you do.
Trash one of them. You can do this, so you must trash one of those two cards.
Discard one of them. You can also do this, so you must do it.
Put the other one on top of your deck. You can't do this because there is no other one, since you only had two to start with. So, you skip this step.
Comment: Be aware that, while Smithy is a "safe" card to play to draw cards, things like Courtyard, Oasis, and Inn still require you to put cards back / discard cards even if you can't draw any.
Comment: A note (much belated): This is all assuming that there are no cards in your deck *or discard pile*. If you need to draw cards but your deck is empty, you first shuffle your discards, draw the remaining cards, then if there are still not enough cards then all of the above applies.


Is a battery charger worth it?

Question: I have a parasitic drain on my car battery. I have a fairly old Ford Fiesta brought from a second hand garage a year ago. It has a new battery. I went to one garage who did a diagnostic test and said it was the body control module and I would need to go to ford. Ford said they needed to do their own test ideally anyway they updated the software and told me to come back if any problems and that I would also need to buy a spare key. Since then I went away and I now seem to be jump starting it every day.
Not sure what damage that would do?
But I'm wondering about whether I should get a battery charger or paying more that the car was worth for a new body control module and spare car keys.
Comment: It could also be that the first garage didn't wanted to be bothered with your car, the BCM is fine and the drain is somewhere else.
Comment: How big is the drain? How many amps?
Answer: A cheap hack is to disconnect the battery every time you stop and leave the car, and reconnect it when you want to start the car and drive. Assuming the car keeps the battery charged while it's running, it's an easy solution.
If you want an easier way to disconnect the battery, you can get a switch.
Answer: Well, you can buy a charger for about 50 bucks that will deal with the symptom.
BUT you may find the bcm fails further and then you will need to replace it or the car... The charger will work on the next car...
Your choice.
Answer: A trickle charger is relatively inexpensive and can help you limp to the next stages of fixing the problem. But it will only help you launch from point A unless you pack it and take it with you, and it will suck to be without juice leaving from point B constantly.
Answer: First, if you are having to jump start your car every day, your current battery is toast (whether it is new or not). You may indeed have a parasitic drain that is the cause of your bad battery, but you still definitely have a bad battery. If it's been drained down more than a few times so much that it won't start the car, it's just never going to hold a charge anymore.
On the other hand, you may not have a parasitic drain at all, and it's just the poor state of the battery that makes it appear to drain down every day. But ultimately something caused the battery to drain. It could be a bad charging system, it could be a parasitic drain, or it could be the previous owner just left the lights on all the time (which will screw up a "new" battery just as easily as it will an old one).
If you get a charger, you are just putting a band-aid on the situation. You also need to definitely find out if the engine's charging system is fine or something is actually draining it when the engine is off. Further, running a bad battery for a length of time can cause wear on your charging system and ultimately you may have an alternator fail, which would then cause even a brand new battery to go bad.  It's really a chicken and egg thing, and if you want to fix it you have to address all of the problems before any one thing can cause other parts of the system to fail, or you'll never make any progress.
Answer: a battery charger is good to have no matter what.  I bought one of those jump boxes for $50 to have in case of emergency. Very smart move on my part.

Is a battery charger worth it?


Finding anomaly detection by pattern matching in a set of continous data

Question: I have series of sensors (around 4k) and each sensor will measure the amplitudes at each point.Suppose I train the neural network with sufficent set of 4k values (N * 4k shape). The machine will find a pattern in the series of values.If the values stray away from the pattern (that is anomaly)  it can detect the point and will be able to say that anomaly is in the 'X'th  sensor.Is this possible.If so what kind of neural network should I use?
Comment: Questions. .. Are the sensors correlated in some way or all completely independent? Are they all required, or can you use a subset?
Comment: Also, do you HAVE to use a neural network? There are easier ways to achieve this.
Comment: Neural Network is not mandatory, any algorithm would do.As of now the sensors seem to be independent.
Answer: Without knowing the kind of data and the process generating it it's hard to give a definite answer.
In general, I would attempt a network that has as inputs the actual sensor readings, and outputs the expected readings. You train this network by presenting data with errors added as inputs, and correct readings as outputs.  It should learn to guess the correct (non-anomalous) readings from a set of actual readings, and you can find the sensors with anomalies by taking the difference between actual and predicted readings.
Depending on the kind of anomalies you expect (misreadings such as fluke zero or max values, or actually anomalous states of the system being measured) your training data should be set up to have samples of such anomalies.
If there are temporal correlations (for example, temperature readings that change slowly) using a RNN might be helpful but its dimensioning heavily depends on the nature of your measured system.
External factors influencing the system (state of a heating mechanism, time of day/year, etc.) could be added at inputs for better predictions.
At the end of the day, trial and error is your friend. Start with a simple network and see how well it behaves. Go for more complex networks when you see where the limitations of the simple solution are.
Comment: Actually the sensors have different idle values at different points.So an anomaly for one may be normal for other and we don't have data for anomalies at each point (at some certain points we have).
Comment: And can you just elaborate the point.Do we have both anomalies and non-anomalies in training? and what I understood is that we have the labels as 'non' anomalous values' ryt? And if the difference between predicted readings and normal  readings are high then as per your explanation is it anomaly or not anomaly?
Comment: It depends on what sort of output is more useful to you. If you simply want to identify anomalous values, then the network should be trained to output binary per-sensor labels. But if you actually want to "remove" the anomaly from the values then the network should be used for regression. I suspect the network for the former use-case (binary classification with simple anomalous/non-anomalous labels) will be easier to train, but this is just a shot in the dark given that I don't know the kind of data you're dealing with.
Answer: Instead of using a neural network, simply sample as many non-anomalous readings from each sensor as you can. If the distribution of the readings from each sensor is approximately normal (check the skew and kurtosis values for the samples from each sensor) then you can work out mean and standard deviation of the samples and, for any future samples, the value of a particular measurement on a normal probability distribution.
(If your measurements do not have a normal distribution, then you can often apply a transform of some sort to the data make it normal).
So, let's say that you have measured a few thousand typical samples for one of your sensors, confirmed that the distribution is normal and calculated the mean and standard deviation of those samples. You can now calculate where on the normal curve your new sample 'x' would be using:
<code>def gaussian(x, mean, std):
    # check for very small standard deviations
    if(2 * std ** 2 == 0):
        return 0.0

    return (1.0/(math.sqrt(2*math.pi) * std)) * math.exp(-((x-mean)**2)/(2*std**2))
</code>
At this point, you can make a decision if the value of the of a particular measurement on that distribution is so low as to be anomalous, and inform the user.
Now, you have probably realised that working out exactly how low a value should be to be considered anomalous might be tricky, and you are correct. The solution is to see if you can get some real anomalous data and use that to set the thresholds. Obviously, this might be rather a job if you have 4000 independent sensors...
If you want to know more about Anomaly Detection then I recommend that you take a look at Andrew Ng's introductory lecture series.


Inorganic Chemistry

Question: Which of the following is a covalent bond?
1.Al2O3                 2.AlF3
3.AlCl3                   4.Al2(SO4)3
The correct answer is AlCl3.But I have a confusion between option c and d.A/c Fajan's rule more the size of anion more is the covalent character. So,SO4^-2 have large size than Cl^-3 .So option d is correct but option c is the right answer.Please explain this question .
Comment: Perhaps because the charge carrying oxygens in sulphate are in resonance?
Comment: But resonance also mostly happens in covalent compounds
Comment: So you have to pull the electron density towards the cation. If those electrons are busy oscillating elsewhere, then won't it be difficult to pull such a distributed electron density? That's what I feel..
Answer: Fajan's rule is correct, but the sulfate ion is complex. We need to ask what is being polarized, a large sulfate ion as a whole, or an oxygen atom specifically. As it turns out, the aluminum acts on a nearest oxygen, so that even if this oxygen is more polarizable because it has a sulfur to draw on, a chlorine is still more polarizable.
Another thing is that aluminum chloride is dimeric in the gas phase, whereas aluminum sulfate is just an ionic solid - although you might still say there is some covalent character in the aluminum-sulfate bonds.
Comment: At the anode, electrons will be removed from something and oxygen will be evolved. The simplest equation doesn't even involve SO4--. The oxidation of water is: H2O - 2e -> 1/2 O2 + 2H+.  If you must put SO4-- in there, then: SO4-- - 2e-> SO4 -> SO3 + 1/2 O2. Then SO3 + H2O -> H2SO4, so you get the SO4-- back, along with 2 H+. So neither SO2 nor SO3 is liberated.
Comment: But since charge is distributed throughout the molecule via resonance, then how can you visualize that only oxygen is being polarized rather than the entire molecule?
Comment: That's the issue that makes the question complex. If the charge is distributed freely, then the anion is large. But if a single oxygen is polarized first, and then, using its slightly deformed charge distribution, slightly polarizes the sulfur, which then slightly polarizes the other oxygens, then you might as well just concentrate on the first oxygen (small anion). So I suppose that the charge does not distribute equally over the whole molecule if only one oxygen is polarized. Degrees of resonance might be an explanation.
Comment: What are 'degrees of resonance'?
Comment: @YUSUFHASAN You don't get what "resonance" is supposed to be. It's about any oscillation. It's about mesomeric structures contributing to resonance hybrid. Also this is a place for  discussion about that, since it has negligible importance for this topic.
Comment: Ok, I get it. Just a final quick question: when the carbonate ion is polarized highly, then it can liberate carbon dioxide gas. Which gas will sulphate liberate in such a case: SO2 or SO3?

Inorganic Chemistry


How to hide certain icons from unity app lens

Question: Ok, so unity is great and all, but something that annoys me that the various systems settings apps show up in the app lens, I don't need them there because there's the system settings menu.  Is there anyway to remove particular icons from the apps lens while still keeping them installed?
Answer: No, there isn't really a way to keep them in the System Settings, but hidden in the dash. But why bother with the System Settings app at all, when you can open the one you want, right from the dash? :)
Comment: Personal preference?


Partitions and Compositions

Question: As everyone knows, the Bell number $B(n)$ is the number of ways to
partition a set of size $n$. Equivalently, it is the number of ways
$n$ numbered balls can be put into $n$ identical boxes. On the other
hand, the number of ways to put $n$ identical balls into $n$ numbered
boxes is $C(n)=\binom{2n-1}{n}$. For $n<10$ we have $B(n)\lt C(n)$ and
for $n\ge 10$ we have $B(n)\gt C(n)$. The question is why does this
switch occur at $n=10$. Is there a combinatorial explanation?
Comment: I doubt it. What would such an explanation look like: an injection from the B-set into the C-set that works only when $n\le 9$, and another injection from the C-set into the B-set that works only when $n\ge10$?
Answer: This is not a complete answer but I think its a step in the right direction
The $B(n)$ and $C(n)$ sets can be relate through code words. A $C(n)$
distribution can be described by a string of occupancy numbers. These
are numbers that count how many balls are in each box. For example
with $n=2$ you can have 2 balls in the first box, or 2 in the second,
or 1 in each. The code words for these distributions are 20, 02, and
11. A $B(n)$ partition can be encoded using code words that
indicate which elements are in the same subset of the partition. For
example with $n=3$ and the set $S=(a,b,c)$ the code words are: 000,
001, 010, 011, 012, corresponding to the partitions: $(a,b,c)$,
$(a,b)(c)$, $(a,c)(b)$, $(a)(b,c)$, $(a)(b)(c)$.
You can map a $C(n)$
code word to a $B(n)$ code word by replacing the first number in the
$C(n)$ word, and all its occurences, with 0, then take the next of the
original numbers and replace it and all its occurences with 1 and so
on until all the numbers have been replaced. The result will be a
$B(n)$ code word. Doing this for $n=3$ gives the following
$C(n)\mapsto B(n)$ mappings: $111\mapsto 000$, $003\mapsto 001$,
$030\mapsto 010$, $300\mapsto 011$, $210\mapsto 012$,
$120\mapsto 012$, $201\mapsto 012$, $021\mapsto 012$,
$102\mapsto 012$, $012\mapsto 012$.
There are 10 $C(3)$ code words with 4 of them mapping onto 4 unique
$B(3)$ code words and 6 of them mapping onto the same $B(3)$ code word. All 5
of the $B(3)$ code words are accounted for by one or more of the 10
$C(3)$ code words. With $n=4$ there are 5 $B(4)$ words with unique
$C(4)$ words, 3 of them with 2 $C(4)$ words each, and 6 of them with 4
$C(4)$ words each. The $C(4)$ code words account for 14 of the 15
$B(4)$ code words. The one unaccounted $B(4)$ code word is 0123 which
would require a $C(4)$ code word with 4 unique occupancy numbers which
is impossible. The four smallest unique occupancy numbers are 0 1 2 3
and they sum to 6.
One way to answer the question then is to explain how the above mapping
works for all $n$. How many $C(n)$ code words map to a given $B(n)$
code word? How many $B(n)$ code words have no corresponding $C(n)$
code word and why?

Partitions and Compositions


Feature selection filter methods

Question: I am confused about when to use which filter methods for feature selection. I tried to learn them through online resources and found methods like chi-square, variance threshold, F-test, Mutual information, etc. As I read through the methods, I got confused with which one I should use. How do I know if the method really selected the most relevant features and did not drop any features that were, in fact, contributing to the cause of the output?
Answer: In general, you need to wrap the feature selection filter method within a cross validation scheme. Here is an example of such an algorithm, assuming you are also tuning hyperparameters.

Split the data into training and testing.
Split the training set only into k folds.
For each iteration of hyperparameter tuning, use cross validation, i.e. do:

For each of the k folds, for iterations i = 1 to k, do:
1) Let the validation set be fold i, and the "inner training" set be all folds not equal to fold i.
2) Using your filtering method, select some subset of your features using some cutoff p on the inner training set. For example, I might filter out variables that have absolute correlation with the target variable y less than p = 0.3.
3) Fit a model.
4) Predict the validation set = fold i. Score the model, i.e. evaluate your function you are trying to optimizer like log loss, mean squared/absolute error, Brier, etc. Save the score.
end

After you are done with your cross validation for one set of hyperparameters, take the mean score over all of the k folds. If the score is better than a previous set of hyperparameters found in a prior iteration, save these hyperparameters.
Note: you can choose to have p, your filter cutoff, also be a hyperparameter here. For simplicity I kept it constant but in general you will probably do better if you tune the filtering cutoff as well.
end

Using the same (or best, if you let it be a hyperparameter and optimized over it in step 3) filter cutoff p, and the best hyperparameters that you found in the cross validation process in step 3, use the training set created in step 1, and fit your "final" model. That is, filter your training set with the cutoff value p using the exact same filtering method you did in step 3. Then, fit a model to this data set using the optimal hyper parameters, also found in step 3.
Predict the test set using your fitted model in step 4. Score the model.

Finally, repeat the entire process again but this time, don't do any filter selection method (omit the filtering process). Use the exact same seeds in your cross validation and at the initial split in step 1 to make sure you are splitting your data the same way from when you used filtering. Now, compare test set scores and see for yourself if there is any benefit to using your filtering method.
In general, I am not a fan of filter based methods because they all introduce some arbitrary cutoff = p and also are all univariate (they don't take into consideration other variables in the model, just in isolation). That being said, they are fast and they might work for your problem.
EDIT: Also, depending on how much data you have and how variable your validation scores are, multiple repeats of the entire algorithm above (steps 1 through 5) might be necessary in order to obtain valid comparisons between using filtering and not using filtering. You would repeat the algorithm above say, N times, once  with filtering and once without for a total of 2N times. You would then calculate an average of averages (find the average score over N repeats using filtering, and find the average score over the same N repeats with no filtering). Then, you could compare scores, form confidence intervals, etc. for a more trustworthy (but also more time consuming) comparison.
Hope this helps.
Comment: Thanks for your thoughtful feedback!
Answer: Check Recursive Feature Elimination (RFE), if you have a labeled data.
It is exacly point out your question : How do I know if the method really selected the most relevant features and did not drop any features that were, in fact, contributing to the cause of the output?
https://scikit-learn.org/stable/modules/generated/sklearn.feature_selection.RFE.html
From docs:
Given an external estimator that assigns weights to features (e.g., the coefficients of a linear model), the goal of recursive feature elimination (RFE) is to select features by recursively considering smaller and smaller sets of features. First, the estimator is trained on the initial set of features and the importance of each feature is obtained either through a coef_ attribute or through a feature_importances_ attribute. Then, the least important features are pruned from current set of features. That procedure is recursively repeated on the pruned set until the desired number of features to select is eventually reached.
Hope it helps!

Feature selection filter methods


Is the National Calling Frequency actually used?

Question: I know that the national calling frequency is 146.520. Everywhere I go, it does not give a DUP or TSQ. I am not trying to be or, ask a crazy question but is there or not.
Comment: @KD8NXH Probably duplex (transmit +/- frequency offset) and tone squelch, respectively.
Comment: This seems almost as if it might be a good question, but it's lacking some details. Try to be more specific about what your issue is.
Comment: I retagged this to include "united-states" since this 'national calling' frequency you mention is out of band in many countries. Given your callsign I am assuming USA.
Comment: @Glenn What do you mean by "DUP" or "TSQ"???
Answer: 146.520 MHz is the national calling frequency for FM voice.  It's a "simplex" frequency, meaning that you call on this frequency and then listen for a reply on the same frequency.  (It is "national" in the US, but that does not guarantee that many people are actively monitoring this frequency! YMMV)
If you're interested in other modes, there are other more-or-less standard frequencies, like 144.200 for SSB voice.
Check http://www.arrl.org/band-plan for frequencies and sub-bands for various amateur bands and operating modes.
Answer: I have my VHF rig in my pickup truck set to 146.52 MHz all of the time when I am driving.  In an hour's time I would guess I hear maybe 3 or 4 copyable signals.  My main use is to help someone out by answering questions that are asked (frequently, traffic snarls and/or other travel related things of mobile operators).
Also, not long ago I was stuck in traffic (south of Tacoma, Washington on I-5) and so I raised up a question on 146.52.  Another guy, traveling in the opposite direction (south-bound) had just passed the accident causing the backup that was about 2 1/2 miles north from my location.  We chatted he got out of range for easy which I am guessing was about 7 to 10 miles.
It is not uncommon for ham radio operators who normally operate HF to have their VHF rig set to 146.52 whether in a vehicle or at home.  In a large city, you can use the simplex 146.52 traffic to ask advice on restaurants or routes or directions and usually pick someone up.  Not as predictable as a repeater but it is a lot easier than programming in your repeater tone while driving in other cities.
Answer: In some areas where there are a lot of active HAMs you might hear some traffic.
Also if you want contacts you do need to call. Just listening for some else to call is seldom a good strategy.
Keep in mind that VHF is fairly sort range especially with a low antenna mount like a car driving down the road in a valley.
if you are looking for conversations when travelling, you might have better luck finding the information on local repeater for the are you are travelling in.
Answer: To answer part of the original question that hasn't yet been answered, duplex (a.k.a. offset, meaning repeater mode) isn't used on the VHF calling frequency used in the US and Canada, 146.52 MHz.  Neither is a tone squelch code, a.k.a. a "PL" tone, properly called a CTCSS tone.  Just plain old FM simplex.
I would think that the calling frequency tends to be used more in rural areas than in big cities.  I live in a rural area, and I hear occasional traffic on it, which is more than I can say for most of the repeaters.  Someone is as likely to be monitoring the calling frequency as the major repeaters in a small town, which makes it a good resource for travelers just passing through; no need to grab the directory and guess which repeater is the one that people actually use.
Answer: Yes it is used, but it depends on your area. I include it in my set of scanned frequencies, and have made 3 or 4 contacts over the past few months.


Resources for Benchmarking Automated Trading Systems available as deltix etc.?

Question: Is there some research resource/group working on benchmarking of software products out there with automated trading and goals of "Advanced alpha generation and execution strategies" incorporating low latency data of the order of milli/micro/nano seconds ?
Comment: What benchmarks do you have in mind for a software product?  Do you mean how fast it runs on standardized hardware?
Comment: As this is an evolving field from low latency ( now ) to zero latency ( trading tech disruption ) some n years hence where smart automated trading robots will dance on the floor as predited by professor john beddington/UK,I am interested to ascertain the major players at intra freq levels with two benchmarking goals of a) trading strategies that generate alpha/profit at milli/micro level atm and b) execution which is more infra related.Also interested about zero latency/auto trading robots at nano level if any atm.
Comment: Well there are a couple of products. But it so happens I am working on such a product which overcomes many of the issues with the existing ones. Ping me if you want to know more.
Answer: There were a few vendors at the 2009/2010 Futures and Options Expo in Chicago that did exactly this. Two that I recall are RTS Group and Solace Systems however their sites don't mention anything of bench marking. Perhaps I'm missing it or they're no longer doing it.
Answer: The fastest systems out there are mostly custom built hardware solutions and even the off the shelf solutions are evolving very rapidly right now. There is a company call Correlix which provides latency measurement of trading systems with extremely high resolution. I have not needed their services and thus I cannot comment on how effective they are.
One thing to keep in mind is that measuring milliseconds and nano seconds is very different and just because something is good a benchmarking milliseconds does not mean it will be good at nanoseconds.


If my web browser is fingerprintable (say, odd window size/screen resolution), who gets to see it?

Question: Does browser fingerprinting leak data only to the server that is answering my request, or also to my ISP or other network-level eavesdropper? Assuming HTTPS (HTTP should leak to the HTTPS "leak set" plus the exit node, I imagine).
Answer: When using Tor the metadata provided by your browser (the data primarily used for fingerprinting) is only accessible to the server as all communication between you and the server is encrypted. If you were not using HTTPS, third parties between the tor exit node and the server would also be able to get the browser metadata.
Answer: Only to the person answering the request (unless there is a faulty SSL setup at their end, which is very unlikely). There are also ways you can avoid sending "fingerprintable" headers at all, but I wouldn't bother.
Answer: The accepted answer is only partly correct. Such fingerprinting data is common to be sold to others by tracking websites. It's a real market out there. So in the first step your data on an HTTPS connection might only be at that server, but whoever is behind that server might decide to sell you to the highest bidder.


Can you send Monero from an exchange to an exchange directly?

Question: Can we send Monero from an exchange to an exchange directly? Lets say from Bittrex to Poloniex, or do we need an actual wallet and send from an exchange to a wallet first and then from wallet to a new exchange.
Is it same with AEON?
Answer: It depends. Several exchanges have a requirement for a payment ID to be included when depositing, but have no option to add it to withdrawals.
In general it's safer to withdraw to an own wallet and then deposit to another exchange, since you can track all steps and in case handle out view keys to prove you didn't get or you sent coins.
Answer: An exchange will use a wallet just like you use a wallet.  The blockchain doesn't care whether you own a wallet or whether an exchange does or whether a robot does or whatever.  So, to answer your question, yes, you can send directly from one exchange to another, since they're wallet is like any other wallet.
It would be the same with any cryptocurrency, AEON included.
Comment: Careful, though. Only if the originating exchange will use the PID correctly, will the receiving one know to credit it to your account, so better test first by sending to your wallet with PID specified to understand if the originating exchange sends correctly.
Answer: There's nothing technically preventing it. However, it depends on whether the sender exchange gives an option to specify the payment ID when sending, and implements it correctly. For example, I remember Poloniex had some bad implementation, where even when specifying the PID when withdrawing, it would show in my wallet as having PID=0x0 (maybe it's fixed now, haven't tried in a while). This would not get credited automatically if sent to another exchange. You can test first by sending to your wallet, and see if they're respecting the PID. If yes, you can try and send to another exchange.
The receiver exchange has no way of knowing whether the amount came from your wallet or another exchange (unless they share user data, but that's another story). What's important is that the payment ID is embedded in the TX, otherwise the receiver exchange would have no way of knowing that the payment should be credited to your (or someone else's, if you so desire) account. So really, it all depends on the sender exchange.


Why do adherents to Hypostatic Union believe that God the Son (Jesus) must be fully Human?

Question: Orthodox teaches that Jesus assumed the full human nature. Why is it necessary that he is fully human?
Comment: I don't know if this is a duplicate, but it is definitely *very* closely related: http://christianity.stackexchange.com/a/7797/1039.  That one asks if Jesus was Human, however, and yours gets to Why?
Answer: Historically, the position of the church on Christology has been explained as "hypostatic union, meaning that Jesus was fully God and fully man).  In the late 300s, Nestorius taught that Jesus' natures were separate.  The problem comes when you consider salvation.
In any Satisfaction theory of atonement, the 'victim' that satisfies God's wrath must be a viable substitute.  As the Christian Apologetics & Research Ministry (CARM) writes:

The problem with Nestorianism is that it threatens the atonement. If Jesus is two persons, then which one died on the cross? If it was the "human person," then the atonement is not of divine quality and thereby insufficient to cleanse us of our sins.

Put another way, satisfaction is untenable, because the sacrifice cannot stand in for the crime.
The opposite error was Eutychism or Monophysitism which ignores the human nature and is not supported by Scripture. Related forms would be if God the Son merely appeared to be human (the heresy of Docetism or Apollinarism.
Monophysitism in general was considered heretical because it denies either the divine or the human nature. Biblically, this negates key passages such as Philippians 2:5-11:

Who, being in very nature[a] God,
      did not consider equality with God something to be used to his own advantage;
  7 rather, he made himself nothing
      by taking the very nature[b] of a servant,
      being made in human likeness.
  8 And being found in appearance as a man,
      he humbled himself
      by becoming obedient to death—
          even death on a cross!

or Hebrews 4:15:

For we do not have a high priest who is unable to empathize with our weaknesses, but we have one who has been tempted in every way, just as we are--yet he did not sin.

that emphasize Christ's ability to sympathize with our humanity. Absent a human nature, that would be a lie.
Liberals, like Dr. Martin Luther King, Jr. go further with this. As he writes:

Where then can we in the liberal tradition find the divine dimension in Jesus? We may find the divinity of Christ not in his substantial unity with God, but in his filial consciousness and in his unique dependence upon God. It was his felling of absolute dependence on God, as Schleiermaker would say, that made him divine. Yes it was the warmest of his devotion to God and the intimacy of his trust in God that accounts for his being the supreme revelation of God. All of this reveals to us that one man has at last realized his true divine calling: That of becoming a true son of man by becoming a true son of God. It is the achievement of a man who has, as nearly as we can tell, completely opened his life to the influence of the divine spirit.

In his moral influence understanding, his human nature that adopted a divine one required as a starting point a human one.
Comment: It seems actually, by the verse in Philippians, that the human nature was only necessary so that obedience to death was possible. That doesn't mean his human nature was full, however. It just had to be enough to die like a human.
Comment: I do see how these verses are difficult to explain for one taking a monophysitic perspective, however, I do not see "satisfaction [as] untenable, because the sacrifice cannot stand in for the crime," simple because that sacrifice is lacking in some nature of some kind. Why is satisfaction untenable for a less than fully human natured Christ? The lambs for example, certainly had no human nature, yet sufficed for a while at least.
Answer: Hypostatic union is define at Chalcedon. But the idea has existed before that.

What has not been assumed has not been healed
St. Gregory of Nazianzus, Epistle 101:32.

Against Apollinarius, Gregory argued that if Christ had not been "endowed with a rational mind, how could he have been a man?" Epistle 101:34. Here, we see how the unity of Christological thought from First Constantinople (381) to Third Constantinople (681) is complementary to each other. Without two wills Christology there is no hope for salvation. Unless the Logos has His own human mind or will, His incarnation achieved nothing. By assuming a human mind He redeemed our nature completely. Our flesh is redeemed because He clothed Himself with a human flesh. Our soul is redeemed because He assumed a human soul. Our will is redeemed because He assumed a human soul with rational mind. This is why He has made His dwelling among mankind. Following Ss. Irenaeus and Athanasius, Gregory continue to defend Theosis. Becoming a man, Christ gave us the possibility of becoming deified.

Let us seek to be like Christ, because Christ also became like us: to
  become gods through Him since He Himself, through us, became a man. He
  took the worst upon Himself to make us a gift of the best
St. Gregory of Nazianzus, Orations 1:5.

Unless God became man we won't be able to be deified, partaking of the divine nature. This is why Christological belief in the hypostatic union include a belief that the Logos became flesh, assuming a complete human nature to redeem our nature. That is the Gospel, He became man so that we might become like Him.


Can a miner remain anonymous?

Question: Can you differentiate the miners from the normal clients, by doing some frequency analysis on ip-addresses that announce new blocks? Or will the new block propagate so fast around the network by normal clients that it's impossible.
Answer: I don't know what this frequency analysis technique would do, so this answer corresponds to the second question you asked:
Blockchain.info connects to hundreds of nodes:

http://www.blockchain.info/connected-nodes

The IP address Blockchain.info shows is the address of one of those nodes that they happened to be connected to which first saw that transaction.  A node where privacy is desired does not allow incoming connections and only connects to trusted nodes that won't violate privacy expectations.
Comment: With frequency analysis I meant just counting for each node how many times it was one of the first to announce a new block. If there is 1 miner and 50 regular nodes, the miner will on average always be faster than nodes that are just relaying. But I guess as soon as the network grows it will be harder and harder, since you can't be connected to all of them at the same time.
Comment: AFAIK there is no way to differentiate between block announcement and block announcement relay
Answer: It is trivial for solo miners to use tor to hide IP adresses. This defeats mentioned above frequency analysis attack.

Can a miner remain anonymous?


Is there any value in publishing screen-cast lectures?

Question: I am getting close to finishing a PhD in applied math (next May), and I'm starting to think about job applications next fall.  I taught for 5 years as a GTA (graduate teaching assistant), but I still feel like my teaching portfolio could use a boost since the last 2 years of my degree I was funded on a research grant.  One idea I cooked up was to create and publish a series of Khan-academy style "screen-cast" lectures on various interesting topics in mathematics.  Since this could potentially consume a fair amount of time, I'm wondering what the benefit of it would actually be for an application to say, a teaching post-doc or tenure track at a SLAC (selective liberal arts college) or (not R1) public university.  Obviously if they're good, it demonstrates an ability to clearly organize and present material, but would anyone actually look at them if they saw it on a CV or in a teaching statement?
Comment: _would anyone actually look at them if they saw it on a CV or in a teaching statement?_ — Yes.  I would.
Comment: Don't make them in order to strengthen your applications.  If you make them, do it because people need them and they are useful.  Also, set yourself some time boundaries so they don't suck away too much of your time.  But by all means, do experiment with this to some extent.  It will broaden your horizons and help you connect with people in ways that take advantage of your particular temperament.  (I read your other recent questions.)
Comment: The value of such courses may be judged, among other factors, by quantifiable metrics such as how many views they get.
Answer: I would advise against doing this, even without knowledge of tghe hiring processes in SLACs (never heard about those before) or the universities you're interested in.
On principle, it does not make sense to have projects in life whose main or only purpose is make your CV look better. If you're passionate enough about this to do it for its own sake - say, because you feel available material is not engaging enough and you had good feedback from your students - then maybe it could be a reasonable use of your time. Otherwise, your days are better doing proper research, or other publicly-visible math-related projects which are of interest to you.
Also, if you got good feedback on your teaching, I doubt your focus on research will be held against you, especially since you do have a solid 3 years. Perhaps some letter of recommendation from professors/lecturers who were in charge of the courses in which you taught could serve as guarantee of your capabilities.
Comment: Not sure I agree. I imagine a demonstrated ability to produce good digital instruction would interest a lot of hiring committees.


What is the most authentic form of yoga?

Question: There are so many different practices that people call yoga. What is the most authentic in terms of being supported by Hindu scriptures?
Answer: The term Yoga is formed from the dhatu 'Yuj'. Panini Dhatupad says following for the meaning of dhatu 'Yuj'.

Yuj samadhau: Samadhi.  So, yoga means attaining Samadhi state/ fourth/ turiya state. So, any path that can lead to Turiya/ Samadhi state can be called Yoga.
Yuj yoge: Union. So, when something is united it is called Yoga. When two atoms are united then it is also called yoga between two atoms. Similarly Union of individual with God/ Universe is Yoga.
Yuj samyamane: Censure. Censuring thought waves in mental pond to see the self within clearly. It is like cleaning the mental mirror to see our own self.

So, any path that leads one to Samadhi or Union with something or stopping of thought waves can be called Yoga. As there can be many paths for this so there are many Yogas.
The 18 Chapters of Bhagvad Gita are classified as Yoga. It is because single chapter can lead one to the Turiya state or Union with something. They are:

Chapter 1 : Visada Yoga
Chapter 2 : Sankhya Yoga
Chapter 3 : Karma Yoga
Chapter 4 : Jnana Yoga
Chapter 5 : Karma Vairagya Yoga
Chapter 6 : Abhyasa Yoga
Chapter 7 : Paramahamsa Vijnana Yoga
Chapter 8 : Aksara-Parabrahman Yoga
Chapter 9 : Raja-Vidya-Guhya Yoga
Chapter 10 : Vibhuti-Vistara-Yoga
Chapter 11 : Visvarupa-Darsana Yoga
Chapter 12 : Bhakti Yoga
Chapter 13 : Ksetra-Ksetrajna Vibhaga Yoga
Chapter 14 : Gunatraya-Vibhaga Yoga
Chapter 15 : Purusottama Yoga
Chapter 16 : Daivasura-Sampad-Vibhaga Yoga
Chapter 17 : Sraddhatraya-Vibhaga Yoga
Chapter 18 : Moksa-Opadesa Yoga

Among these Karma Yoga, Jnana Yoga and Bhakti Yoga are most popular in todays time. Some Yoga fall in sub branches of these Yogas.
Now,
Ashtanga Yoga:
As the name implies it is eight limbed Yoga. The eight limbs are:

Yam, Niyam, Asana, Pranayama, Pratyahara, Dharana, Dhyana and Samadhi.

Patanjali in 'Patanjali Yoga Sutras' describes this Yoga. Several other Puranas also describe it.
As in the eight limbs the final limb is 'Samadhi'. So Ashtanga Yogas main goal is to reach to Samadhi. But todays people don't even think about attaining Samadhi. They just practice Asana (specific position) and Pranayama (breathing techniques). And people now think main goal of Yoga is for removing diseases.
Kundalini Yoga:
Kundalini Yoga is also somewhat popular. It is also scriptual based as I discuss in my answer here.

Uniting the Kundalini (Shakti) with Shiva sitting in Sahasrara by crossing 6 chakras in the path and thus attaining Kaivalya is Kundalini Yoga.

Hatha Yoga:
It is based on six limbs which are:

asana, pranayama, pratyahara, dharana, dhyana and samādhi.

Shat-Kriyas applied for purification of body are

Netī, Dhautī, Naulī, Basti, Kapālabhātī, Trāṭaka

They are related with fully cleansing body including internal organs, 'Trataka' is used to gain extreme concenteration and thus leading to Samadhi. It was discovered by Guru Gorakhnath, Matsendra Nath and Other Nava Naths. So, mostly people of Nath Sampradaya Practice this.
Raja Yoga:
It is related with controlling of mind. It is also described in Bhagvad Gita chapter 6. For eg verse 6 says:

"A yogi should always try to concentrate his mind, retiring into solitude and living alone, having subdued his mind and body and got rid of his desires and possessions."
For more details see answer here.

Kriya Yoga:

It is advanced Raja Yoga mixed with Pranayama exercises. See answer here. for more details.

There can be other several Yogas like Mantra Yoga (attaining union through mantras), Tantra Yoga, Yantra Yoga and so on many other Yogas. As there can be infinite paths to reach Supreme or to Unite with something, so there are infinite Yogas. One should choose path/paths which is/are suitable for him and finally be united with what he desires
Comment: @KeshavSrinivasan but Raj Yoga focuses on mind control and Aasana.... whereas Ashtanga Yoga focuses on Aasana, Pranayama and mind control... Raja Yoga doesn't focus in Pranayama...
Comment: An excellent answer. Yes, it was 2nd international Yog(a) day a couple of days ago, and whole of the Internet was filled with people who are too much into *Aasan* (even a contortionist would blush). The aim of Yoga is to find inner peace, unite soul with God, be one with the omnipresent Brahman. Meditation is also a step or level in yoga, hope that fellow yoga enthusiasts find it fascinating and do it for the world peace. हरि ऊँ
Comment: Raja Yoga and Ashtanga Yoga are the same; they're just different names of the Yoga school of Patanjali.  By the way, you may be interested in the disproof of the Yoga school given in the Brahma Sutras.  Also, Adi Shankaracharya states in his Brahma Sutra Bhashya that Ashtanga Yoga is not a valid means of attaining Brahman.
Comment: My understanding is that Raja Yoga is just a name that Vivekananda gave for what was traditionally known as Patanjali Yoga.
Comment: @KeshavSrinivasan they are same but there is subtle difference I think..I think one can do Raja yoga without any physical exercise also.. just by mind control... Wikipedia says " The term also became a modern retronym, when in the 19th-century Swami Vivekananda equated raja yoga with the Yoga Sutras of Patanjali"


Cook a frozen cobbler in a microwave instead of oven

Question: Here's my problem. We don't have access to a oven (we are out of town for a week and out hotel room only has a microwave and a 2 range stove top). I purchased a frozen Blackberry Cobbler and we want to make it. Does anyone know how long I should cook it and is it safe?
Answer: It would almost certainly be safe, as there is nothing in a cobbler that could not be eaten if you just thawed the cobbler and ate it raw.
It is unlikely to be as good as when cooked properly in an oven because:

The topping will not crisp up
The microwave will not cook evenly, and you cannot stir a cobbler; you will most likely end up with cooler spots where any thickeners in the filling didn't gel, and still taste a little starchy, and other spots where the fruit is overcooked

It is not really possible to give you a time to use because, even if there was some sort of "oven to microwave" conversion factor (which there is not):

Microwaves vary in power output
The size of the cobbler in question will make a big difference

If you can take it home frozen, I would cook and eat it at home once you have access to a normal oven.
Comment: I'll suggest turning down the power on the microwave. That'll help a lot with the unevenness. Also, beware if the cobbler is in a foil pan, the foil will block the microwaves—or worse, start arcing. You will need to transfer it to a microwave-safe pan.
Comment: Related to the safety angle, I think if I *really* wanted to use the microwave and didn't have access to an oven, I'd just let it thaw on the counter before heating it in the microwave. At least it will cook more evenly that way, even though it still won't crisp and probably won't be great in general.
Comment: Also, depending on the topping, it may be not really palatable.  An oatmeal topping may get mushy in the 'nuking or it could turn into bits of concrete.  I go along with @SAJ14SAJ and recommend taking it home frozen if you can or if you are willing to risk wasting the money you spend on it, go ahead and try cooking it in the microwave and see what happens.  Good luck!


Max lifetime of transactions in mempool?

Question: If a transaction sits a long time in the tezos mempool for a reason or another does it get eventually cleaned-up or will it stay there forever ?
Answer: In the current protocol there's a time to live of 60 blocks for every manager operation, after which they can no longer be included.
Answer: NB: After the adoption of the Granada protocol, which halves the minimal time between blocks, the max_operation_ttl constant was doubled from 60 to 120 blocks, to roughly preserve the length of the live blocks and operations window when measured in wall-clock time.
NB NB After the activation of the Mumbai protocol upgrade further halved minimal blocktime from 30s to 15s, this constant was consequently doubled, again, from 120 to 240 blocks to preserve the invariant.


How can I evaluate the quality and value of a violin?

Question: I want to start learning the violin, but I don't know what's a good price for one. Should I get a used one or a new one? How can I tell that a violin is of good quality and worth the price asking for? What's a good brand?
Answer: I'm about at the same point (maybe a little bit ahead, but not much), so I'll help with what I can.
Violins are a bear to learn, for three reasons:

intonation - Keyboards only have one note per key. Guitars have whatever note the fret and the tuning give. With violins,  intonation is determined by your fingers. Unless you are a very special person, you don't have the notes in your ears, and you'll have to spend lots of time playing along to CDs before it doesn't offend your ears.
ergonomics - Violins are held between your shoulder and chin. If you rest the violin on your hand, your range of motion is severely hampered.
bowing - Bowing is hard. You have to be able to separate your bowing from the rhythm of the piece. I play guitar, and I bow like I play guitar. I saw the thing, and it is sad. Beyond the rhythm of the thing, pressure and angle and such mean a lot, and little things, I am told, are the difference between a great musical tone and a screech.

Because of these things, picking up the violin is not something to be taken lightly, and there is great chance of giving up before you climb the learning curve. So, my suggestion is to get an inexpensive instrument.
There's no big names for violins like there are for guitars. I mean, there are bigger names, but there isn't a Fender or a Gibson or a Martin. This makes it easy to skirt the no-shopping-advice dictum. On the acoustic side, violins are pretty much of the same material and of the same shape, so the good ones and the bad ones will superficially be alike. Beyond that, remember that the violins that were used by great classical players were not the ones that ended up in the hands of folk players, so, if your desire is to play fiddle, rather than classical violin, your desire is for an instrument that has different characteristics than a classical violin. Bows are a big determiner of the tonal characteristics, and so your bow could end up as expensive as your violin.
So, after that info dump, my suggestion is to find a cheap instrument and work with it. You should be able to find something between $100-$200, which is at the low end. (Fine contemporary maker violins go into the tens of thousands of dollars. I wish I could tell you what distinguishes them, but I've never touched one.) You'll eventually learn something about what makes an instrument sound good, but believe me, you need to work a lot with your ears and hands before the instrument itself is the determining factor.
Comment: Ahh. 233 named Strad violins. http://en.wikipedia.org/wiki/List_of_Stradivarius_instruments
Comment: As a reasonably good pianist who was once a beginner, I can say that the things you'd think are important in an instrument as a beginner aren't the same things you'll look for when you're experienced.  Spending a lot of money on an instrument as a beginner is a mistake.
Comment: I gave few details about what details were, and this is why I said "superficially". An experienced player understands the details, which is why the best players play fine instruments and not $100 made-in-China instruments. As a fiddle owner and guitar player, though, I bow to your greater experience.
Comment: :-) I know @VarLogRant - was mostly joking. You got an upvote from me anyway as I think your answer is spot on.
Comment: `On the acoustic side, violins are pretty much of the same material and of the same shape`, compared to how guitars have different shapes, maybe, but from violin to violin those are actually very big differences. The wood used changes a lot, the length can vary by as much as a cm (this may seem not a lot, but it *is* when you hold it), some are wider, some thicker, the head will vary from maker to maker. I mean, I think I just wholly disagree with what you seem to consider as a detail. We're speaking of violins here, details are everything!
Answer: There are only two factors, although they are broad:

does it sound good?
does it feel right?

These are difficult for a beginner to know. You haven't the experience to know if an instrument feels right. You haven't the skill to bow a note well enough to gauge its tone.
Fortunately, unlike a guitar, where fat necks and bad fret intonation can really hold you back, within reason, you can learn on a cheap violin.
So, if you can, take an experienced violinist shopping with you, let them play the instrument. They will be able to tell you if it feels right, and both of you will be able to make judgements about how it sounds.
One further objective factor, is whether it stays in tune. That's easy enough -- just check that the tuning pegs are firmly fitted.
If you can't find a violinist to help you, don't worry too much - consider learning with a borrowed instrument, or a cheap instrument, until you've learned to sound a pleasant sounding note. By then you should be able to tell a pleasant feeling instrument when you play it.
The best way to start learning is with a teacher. See if your teacher can help you find an instrument.
Answer: My advice (violin teacher since 1986) is to rent one first, save $100 a month for a couple years and get something decent.  Try out several and take them to your lessons for your teacher to try out and advise you on.
Good luck
Answer: I agree with VarLogRant, there are no big names (in reasonable price range). Traditionally violins involve a lot of manual work, which limits the number of instruments by one maker. There are increasingly mass-market instruments more industrially manufactured from Asia and much of discussion is going on, how carefully the wood was dried and how likely they develop cracks later. They may also be good, but beyond holding the tune the criteria are not easily recognized. In any case you should take some lessons and the teacher should try the instrument.
Answer: Since the part about pricing seems to have been answered, I'll concentrate on the what is a good violin part, first by distinguishing between types of violins.
There are actually schools of violins; nationalities; not unlike the different schools of playing the violin. Amongst the most popular nationalities (which regroup general guidelines on how violins are constructed) are

french
italian
german

That being said, this applies mostly for older violins. Now, we are getting in a contemporary world of violin making, and while there are still violin makers who will imitate styles of older violins, violin-making styles will vary from maker to maker.
How to distinguish a good violin from a bad? Here are some hints, but it varies greatly from tastes to tastes.

stability in tone. the board must be even, so that your finger, placed on a string at a definite position, will produce the right note (a fifth higher) on the next string (taking into account that your violin is tuned). Violins of lesser quelity will have uneven boards that require you to actually have different left-hand position from strin gto string.
sound! or more precisely, a range of sound. you want your violin to be able to produce sounds from pianissimo to fortissimo. you want the pianissimos to be heard even "far" away from your violin. say you try it in a hall, even when playing very soft, the sound of good violins will travel to the end, and be heard.
colors. when playing close or away from the bridge, good violins will present a wide range of sound colors, normally ranging from something like a pan flute when playing almost on the board, to a screeching brilliant sound when getting closer to the bridge. you want those colors.

Keep in mind that those are kind of hard to hear, but try many violins and you will start to hear differences between them!
Answer: You can also contact some of you local violin luthiers. They will have all the knowledge pertaining to the condition and source of your violin. Also even if many of them do sell instruments they are not as desperate in there need to sell you something that what is the case with a guitar centre type of music shop.


On recumbent trikes, vs road bikes which is safer down hill?

Question: Tadpole, vs delta have different tipping modes. Does the three wheel configuration give a false sense of stability? Are rocks on the road more or less of a risk on a Tadpole vs Delta vs Road/Mountain bike?  I'm thinking of "graduating" to a trike for stability reasons. I don't want to experiment if I can avoid it.
Comment: The meaning of the above is: if you feel your recumbent is safer, this might lead you to more risky behavior (going faster around curves, riding on loose gravel), that might increase the risk beyond the safety factor. This has been found to be the case in automotive safety, c.f. ABS systems.
Comment: One advantage of a tadpole (two wheels in front) is that you have almost double the braking power and less propensity towards fade. It's difficult to say which is safer, though, as it depends on your riding style: you can't make something foolproof as there's always a better fool around the corner.
Answer: Safety on descents is more a matter of your state of mind than any objectively measurable phenomenon.
I will say that I have descended pretty damn fast on a road bike, and faster on a tadpole trike. This had less to do with being on three wheels and more to do with having an extremely low center of gravity on the trike. I've also never experienced speed wobbles on my trike--I'm not even sure that's possible.
You do not tip on a trike or bike when you're going in a straight line. If you're going through curves, the fact that you cannot lean into a turn on a trike means that you can flip the trike instead, and at higher speeds, you'll flip the trike on shallower turns.
Typically, tadpoles have two front brakes, and for the most part, this is a benefit. Braking at very high speed will steer the trike into the braked wheel; if you apply both brakes, then the slightest discrepancy in the application of the brakes can cause a dangerous back-and-forth when you're whipping downhill.
From what I've seen, a tadpole can be designed with a lower center of gravity than a delta, which improves stability.
If the road surface is too broken up or littered with debris for me to descend at full speed, then I don't, regardless of what I'm riding. I suppose in the abstract I would feel more endangered hitting a given rock at speed on my road bike than I would on my trike (I also have much fatter tires on my trike). It would also be harder to avoid the rock on my trike (three tracks vs one). But that's a hypothetical I am not eager to test.
Comment: I do want to clarify that the statement "...If you're going through curves, the fact that you cannot lean into a turn on a trike..."  is not entirely true.  Many recumbent trike riders, including myself, lean quite well into corners at higher-than-typical speeds, and those of us with experience and a rear brake even understand the advantages of sliding out the rear wheel to aid in cornering fast.  You _can_ lean into corners, but you _do_ need to understand the limits of your trike to make leaning effective and know where the tipping point is, understand the surface you are riding on, etc.
Comment: Thanks for this. It is sort of what I expected and that's what I wanted to hear!!


How do I play well as a scout?

Question: Being fairly new to TF2 (about 100 hours play time) I am becoming steadily proficient in most classes, and am having a great time with them. However, one class, the scout, is eluding me. When I play as scout, I am killed very quickly and am lucky to get a single kill. However, when other people play as scout, they run circles around me and kill me quickly. Clearly they are doing something that I'm missing. How do I play well as a scout?
Comment: Normally "how to play..." questions would generally be off-topic, but TF2 do very much have a well-refined class structure, so this is actually valid.
Comment: Related: http://gaming.stackexchange.com/questions/18868/avoiding-cheap-deaths-in-tf2
Comment: There's also loadouts to consider, but surprisingly the Scout doesn't get affected by Loadouts that much, other than the use of Bonk! and possibly FaN.
Answer: Scout is a class with a very high skill threshhold to clear - playing Scout and doing it well is very difficult, especially for a new player.  They move faster than any other class, making it more difficult to aim properly.  And they have the lowest possible base HP of any class (unmodified by loadouts).
Mobility is key to playing a Scout.  You never want to be in one place for long.  Jump, weave, and duck into side-corridors to get away from danger.
You are vulnerable, and you do not want to get into a head-on fight, even against weaker classes.  Instead, use side-corridors to flank and get behind other players.
Your Scattergun (and the FaN if you have it) are powerful close-range weapons.  Don't shoot until you're up close and certain of getting a full-body shot.  The more pellets you can get into them in a single shot, the greater damage you'll do.
You can take down most classes in just two shots at close range, which is faster than most classes will be able to react.  If they do, dodge, and if they are well aware of your presence, run.  You are outgunned by almost every class that isn't support-based.
Avoid sentries.  Always, always avoid sentries.  Use Bonk! to get past them, pick them off with a pistol, slip by them if they aren't pointing directly at your pathway, but avoid them at all costs.
Finally, above all else, practice.  Every class has a skill threshhold you need to get past before you're 'good' with them, and the Scout's the hardest class of all to get used to.  Watch some video clips, watch what other players do, read the TF2 Wiki pages on Scout Strategy and match-ups, but practice above all else makes perfect.
Comment: Excellent, in-depth answer. Thanks for your help, I'll give it a go
Answer: The best way to get better with it is to train, and to know the pros and cons of the class, so look at guides like this one for example : http://www.wikihow.com/Play-As-a-Scout-in-Team-Fortress-2
The scout is faster, has double jump, but the price is a low health. Use your strengths and move as much as you can, so they can't touch you. All i can say is start with a guide for the basics, then train and watch videos of good players.
Answer: The top advantage of scout is double-jumping and speed. remember, because you have low health, never stop moving. if you want to kill players, jump around, run around them to make hard for them to kill YOU. Basically, be a nuisance.
If you play capture the flag(best for scout), there will be a point linking both team's bases, and that point will have many enemies. so go left right, jump around, to survive. you would want run past everyone(don't fight a group of people!) quickly, grab their team's intelligence, and return to your base afterwards. watch out for sentry guns.

How do I play well as a scout?


How does a router use the routing table to choose the outgoing line?

Question: How does a router know which is the best line on which to send packets. I mean, the routing table most often does not contain the entry for the destination network number of the IP packet. It only knows the destinations adjacent to it or nearby. It does not know if the address exists or not. Say I make a request for stackoverflow.com to my LAN proxy. Next it sends the request to a router. How is it that the packet is transported all the way to a server in the US using an optimal path seeing that that router knows only nearby addresses?
Thank you in advance...
Answer: Towards the edges of the Internet, each router has one or more default routes.  The default route is used for all destination addresses for which the router doesn't have a specific route, and points "inward" - ie. it is assigned to the router's upstream link.
Each packet will therefore tend to flow upstream, towards the core of the network.  As you get closer towards the network core, the routers tend to have larger and larger routing tables - they "know about" more networks.  The core routers themselves do not have default routes - if they don't know how to get to the destination, they just drop the packet.  The routers at this level use an exterior routing protocol, BGP, to exchange routes with other core routers.  If your packet makes it this far, it will then start flowing downstream again, until it reaches its destination.
Answer: A router has a list of IP address/netmask pairs for each interface.  Anything that is destined for that network will be sent directly on that network.
Anything farther away will be listed under a "next-hop" router.  Your router will forward the packet to the next-hop router, using the appropriate local interface.
If the router doesn't have a map for the given destination, it will instead be sent to the default "next-hop".  This is the default for your local computer or for a home router/firewall combination.


How is congee made?

Question: Does anyone know how to make the congee like those in Dim Sum/Yum Cha restaurants?
Comment: Which kind of congee do you want? Chiuchow plain or with added ingredients, maybe bean-curd or beef, chiken, perhaps noodles. is it deep fried? There are lots of variations.
Answer: Congee itself is just thick rice porridge. It is usually made with a combination of short-grain and 'sticky' (glutinous) rice, but any kind of white rice will work.
Put 3/4 cup rice (1/2 cup regular, 1/4 cup sticky, if you have it) in a pot with 8 cups of water and a little salt. Bring to a boil and simmer for 1 to 1 1/2 hours, until it is a thick porridge. Stir now and then so it doesn't stick. Many electric rice cookers have a congee setting, which makes everything really easy - just put in a measure of rice, add water up to the congee mark, turn it on and wait.
There are many, many traditional toppings or additions to congee. Eileen Yin-Fei Lo said it well in her "From the Earth: Chinese Vegetarian Cooking": "Virtually any food can be added to one's breakfast congee in China. What you might add to it depends upon your preferences."
Comment: I would also add that instead of just straight water, you could also add a little stock or soup bones to the mix to add extra flavour to the congee.
Answer: Just wanted to offer a cheaper variation to this. Presoak the rice with a tea spoon of salt and a tea spoon of vegetable oil overnight or for half an hour if you're in a rush. Basically, the longer you presoak the rice, the less you need to cook the rice in water before it begins to break apart. Simmer the rice and water solution with additional water, stirring occasionally. You should see the rice gradually thicken until it begins to break apart. About ten minutes after this is a good time to stop. When the rice first begins to simmer, you can add chicken stock and or pieces of chicken leg. Traditional congee often has meat with bones!
Flavour with more salt. Some popular condiments include fried peanuts and freshly chopped spring onions. Stir these in after cooking for a fragrant treat.

How is congee made?


Is there as way to export a blender object for cnc machining so it doesn't become a huge file size when converted to .stp?

Question: I am a beginner. I want to export a blender object to be cut on a CNC machine, the workshop ask me for a .stp file or a .igs file. My blender object has 250,000 tris, when I export to .stl the file size is 9mb but if I convert this file to .stp it becomes a huge 500mb file. Is there anything I can do within Blender before exporting the object to make this file size more reasonable?
Comment: By the way... in addition to the suggested answer below: Many CNC machines can be driven off Adobe Illustrator files, which are vector based. If your final object is a two-dimensional print on a cut-out, place your raster image inside an AI cut line.... We do this quite a bit.... But for machining a true 3D model, see answer below.
Comment: Another option is to export the G-Code straight from Blender using [BlenderCAM](http://blendercam.blogspot.co.uk)
Answer: This is a good question, and the answer unfortunately is mostly "no". IGES and STEP files are (mostly) CAD/CAM files, and are not point- or polygonal-based. The file format itself is ASCII, and dates back into the 70s. It is great for driving CNC machines, since that's its history.
Some modeling programs (Rhino) can get you there from nurbs-based modeling. I am not aware of any option in Blender (or ZBrush, Maya) allowing you to get a clean IGES.  You can get STL files, which are great for 3D printing and which some routers will accept.
There are a number of programs that will go back and forth between Nurbs, STEP and IGES...  and some higher-end products (SolidWorks) will bring in an stl and generate an IGES or STEP.
If you finda  better answer -- post here. We use Blender for a lot of 3D output, but when we need tooling, typically we need to have IGES... and this is the best info I have at the moment!
Comment: I used the affordable automapki autoconverter to convert my STL to STEP, it appears to my inexperienced eye to work fine for objects with a few thousand tris but anything bigger and the files get huge. The object will be a core for a lost wax bronze sculpture so detail is not so important, I will sculpt that back onto the wax before casting. I may have to cut it as a low poly object with the CNC machine and finish it off with sandpaper, not the ideal solution!
Answer: You could also potentially just convert your model to STL and then have your part 3D printed in PLA. There are some good videoes on youtube of people using 3D printed PLA parts over wax for casting. Check on 3D hubs for an affordable printer near your location. Also check out fusion 360. It is a free CAD program. You can export from blender to obj, and then import into fusion and convert the mesh into a BREP which you can export to step. Converting from mesh to BRep can be tricky if you don't have a clean mesh. You may need to use netfabb or meshlab to repair it.
Comment: please try to keep answers based around blender.
Comment: I don't think this is about blender, and I also don't think it answered the question.