Studying Anatomy

Question: I am having troubles studying anatomy. Specifically, memorizing all the relations, courses and branches of certain arteries or veins. Can someone suggest a good way to study efficiently? Thank you.
Answer: This is normal, anatomy is a complex subject to grasp at first. I can suggest the following to help you study more efficiently:
Learning Strategies

Begin by knowing all systems of the human body
(learn the skeletal system first and then the muscular system etc.)
Focus on a particular system and visualize its parts
(learn the head and go down or start with fingers then limbs etc.)

Learning Approaches

Exercise your knowledge and ability to recollect using anatomy flashcards
Actively engage in your learning (don't only read), color and explain relations
Answer: Aitía gave you good answers to start with in structuring your learning: If you sort into digestable chunks what is up for learning, you can feed your long term potentiation with the necessary repetition.
A friend once told me that he started to learn the (peripheral) nervous system first, so he found it easier, later, to attach muscles, and then muscles to bones - this approach is a functional one, not a structural one, though.
I happen to memorize things better - and research has shown that to be effective for the brain - when I imagine a patient case (a pathology) related to an anatomical structure. If that is what you like, books of functional anatomy (you can lay them out side to side with those of structural anatomy) tend to explain more clinical cases or "why's". Find something that connects the content to your life, so that your brain thinks, "aah, that is why that matters", for example, if you do fitness, think of how muscles stretch or contract when you make a movement or how ligaments limit a certain movement etcetera. Many books come with clinical cases (take, for example, golfer's elbow - you may palpate your own Epicondylus medialis when making a fist - this lets you remember where the flexor muscles have their origin). The sensory experience of palpating what you just "learned" turns theoretical knowledge into practical knowledge. "Learning" often meant to the brain that the two were apart, and this performative approach often meant fatigue, thus, the disappearance of joy, which is a central motivating factor in the physiological learning of children.
You can also be rigorous and make a learning plan. That is suggested in an exam preparation book series (The GK Series by Thieme, referring to a forum for German medial students, medi-learn.de), here a summary in my free and brief simplification:

reserve 6-8 hours / day for learning, 5 days a week

keep track of until when you want to (or "have to") learn "what"

don't learn too much "all new" stuff on one day/session, repetition is okay

if it is too complicated, learn it in chunks

read/learn before noon on one day, what you check/ask yourself in the afternoon of the next day (you can connect the dots with Aitía's flashcard example here)

truly seek in yourself what you know already, before you look at the back of a flashcard too fast

Let me add: There are also flashcard learning systems that put aside those cards you either labeled "I don't need to repeat THAT", "I could repeat that" and "I should repeat that".

It may also be worth to note that learning benefit from healthy sleep, even only naps, if the brain becomes tired after learning (studies show that after sleep, long term potentiation is improved). Most probably, if you ask it, your brain tells you about the way it likes to digest certain types of information. The more neurons blink, the more connections you make because things and their interdependence become important to your growing understanding, the better the connection between them gets and long term potentiation is reinforced. Podcasts, for example, can be a medium to listen to in supermarkets or subways, still keeping your mind "at it" ... I also imagined me being very small and the structures of the body like roads I'd travel (the french series "Il était une fois… la Vie" may have stimulated that). There is also good 3D visualisation software out there, if you look for it.
There are types of questions explicity linking the "chunks" of structural anatomy, like "What nerve innervates this muscle/organ", "what muscle sits on that part of this bone", "which ligament restricts that joint movement" - you see that my anatomy is more or less based on musculoskeletal needs, but you might want to take that as a metaphor. In school we had a guy whom I talked to about his learning, and he said: "I don't learn muscle functions at all, I simply remember where they are and then imagine what happens when they contract". He was somehow already thinking like the body when I was still learning some thinking. (However, the full scope of some muscle function also can't be explained by just looking at a drawing of them, but he made an important point to my slightly overfocused and a little bit narrow minded brain at the time. I was so busy in attempting "to get it all right" that I lost the big picture, "that I can, basically, grasp things", just not all at once).
If you speak with a buddy (like with us, here), but maybe off-Internet, you get a taste of the personal depth their learning had. One of my other buddies was the son of a doctor. He had a serious love for the stuff. Man, that still inspires me today! It helps me to understand that whatever I understand, "why do I have the feeling he'd understand it better"? But through always knowing-or-feeling that, I always learn, and it never gets really boring ... :)
In the end, I wish to you that you can make learning fun and sometimes think of the smiles of the people that are grateful, when you help them .. it is really the most rewarding thing. My greatest joy is in balancing mild leg length differences with marginal heel lifts and check the results of possibly symmetrically aligned zygapophysial joint movement (with palpation, while radiology hardly is there so far). Here, I desperately need functional anatomy :)! Hardly anyone does mild leg length difference compensation in such relative precision, it is very successful and people are so thankful. Really strange that there's not much more science about "the hard problem of practical relevance" for LLD/LLI, which is of course my favorite example for why learning matters and is fun. I wish you all the success you can have, and that you find your own "favourite problem" to work with! Go for it :) !

Studying Anatomy


Re-sodding to solve weed problem without use of herbicides

Question: Our lawn is overridden with weeds (mostly dandelions and clover).  Part of the problem is we have not done much to maintain it over the years and also we don't use any herbicides.  I wanted to tear up the current lawn and put in new sod.  The company I spoke to said they would dig out about 3 to 4 inches and put in a fertilizer (I made it clear no herbicide) and put in about 2 inches of triple mix and resod. They think this should solve the weed problem. Another landscaper I spoke to seemed to think this is a waste and they will just grow back if we don't use a herbicide first to kill them, as the roots can go deeper than the 3 to 4 inches.  Can somebody please advise? (We live in Mississauga, Canada)
Comment: Your choice, of course, but don't forget thatt one gardener's weedy lawn is another gardener's wildflower meadow. Unless you're maintaining a sports turf surface such as a tennis court or bowling green why worry about dandelions and clover?
Answer: The second landscaper is right. If you get someone else to do the job, they will either need to kill the weeds with herbicide, or they need to dig out each weed separately, extracting all root material, and that may mean going down 8 inches or more to get out a dandelion root. If this is not done, they will regrow through the new lawn.
Comment: The first landscaper may be betting that they won't regrow for a few months, after which if you complain about the work he can say "no, I killed all the weeds that were originally there, these are new ones."
Answer: You don't need to resod as chickens work well on grass, and there should be diversify in grass so you don't need to fertilize as much if you do. The number is depending on the size of the area you're stripping of plant life.
Answer: That's overkill and expensive, weeds like dandelion and clover are indicative tell tale signs of lawn health.

Clover, lack of nitrogen
dandelion: compacted soil
Better strategy is to mow the lawn down golf course style short and let it regrow, then manually remove any weed that pops up. Also your soil may be compacted so it's best to aerate and seed.


Contact membership ID based on a pattern

Question: Newbie question.
I'm looking for a way to add a custom field to each contact that will be a unique membership ID but based on a pattern, eg. 2019-### etc.
I'm using Civi with Drupal 7
Comment: Given that there is already a unique Custom Id for both the Contact and any Membership they purchase - in what context do you need your 2019-###. If you only need it for a display/list then you could just create this in a View by grabbing the year of payment, and the membership id (or contact id) and concatenating them in the display
Answer: I also used ContactID to hold membership ID for the same reason that a unique value is allocated by CiviCRM. There doesn't seem to me any standard way to have an autoincrement field in CiviCRM without doing some coding. You also have to think whether the membership ID should be in the membership record rather than the contact record, though because I had some historical data, I decided against this. To get the historical data in I created records for all the membership numbers up to the last one previously used, but tagged all that hadn't been used so that I could delete them all later. I think imported all these records and they were automatically allocated the matching contact id (fortunately I didn't have a membership 1 which was already allocated to the admin account. I then deleted the contacts for the numbers that hadn't been previously used. New contacts were autoincremented from the last one I had used. You might be able to do a trick to get your numbers starting 2019 etc, but that would mean creating a hell of a lot of records and then deleting them, so not sure its a sensible option, but you could try (maybe with just a 19 prefix, so you would be OK for the next 80 years).
I don't think that CiviRules has anything built in that will create an autoincrement field. Indeed I can't see something available off the shelf to set a custom field. I think you would need to write some code.
Answer: One way i could think of is to create a custom field on contacts, and use hook_civicrm_post hook using following conditions:

$op = create
$objectName = contact

You will get contact Id in $objectId variable, then you can use CiviCRM API to update custom field value based on whatever pattern+contactID you desire.
Thanks
Answer: I would check out the CiviCRM docs to create a custom field: https://docs.civicrm.org/user/en/latest/organising-your-data/creating-custom-fields/
We used the Contact ID for our membership ID's because they are automatically a unique ID. For something like 2019-### you would probably have to manual enter each or write something to do that. You could maybe use CiviRules to help.


In what way are the airfoils used for a propeller different from the ones used in turbofan engine?

Question: Airfoils are used in the blades of a propeller as well as the blades of the fan, axial compressor and turbine in a turbofan engine. Thus, the airfoils used in above two applications have different purposes. In propeller, the lift from the airfoil is used for generating thrust. Whereas, in a turbofan engine, airfoils are used for adding and extracting work from the flow in the compressor and turbine sections respectively. Therefore, my question is what are the characteristics of the airfoils employed in both propeller and turbofan engine, and how they vary from each other. Also, how different is the blade section of a fan with respect to the ones in axial compressor and turbine.
Comment: Note that in turbojet engine, most of the thrust is still generated by the compressor—in fact, there is more force acting on it than the total thrust, because there is negative thrust on the turbine cancelling part of it—and that a propeller also adds work (energy) to the air stream. So the principle is exactly the same in both cases. The difference is mainly in the speeds involved, the fact a compressor works against a pressure gradient, and the solidity ratio.
Answer: The angle of attack range of a propeller airfoil is larger than that of a turbofan. Therefore, the turbofan can get away with a thinner airfoil and much more camber. Also, the aspect ratio (ratio between length and chord) of a propeller blade is much higher, so the airfoil needs to be thicker to allow the blade root to carry the radial loads and to produce less torsion so the propeller blade does not twist too much under load. Were the turbofan blade as thick, the higher solidity of a typical turbofan would mean that the fan blades would block most of the flow path.


How to Modify a Font to Fixed Width in Fontlab

Question: I use a text user interface application on a server that I access via a Terminal. I have been using the Futurist Fixed-width for some time on a Linux PC in Gnome-Terminal, and would like to use that same font on a Windows PC with Putty.
When downloaded on a Windows PC, this font does not display as an option. I believe this is due to it not being correctly marked as a fixed-width font.
I have downloaded FontLab VI and attempted to mark this as a fixed-width font (Font Info > Monospaced), but it does not seem to be committing. When I open the exported font again in FontLab, I see that it again not marked as fixed-width.
I'd love to use this font in PuTTY, and am not committed to using any particular program to accomplish it.
Any suggestions?
Thanks.
Answer: You need to have Allow selection of variable-pitched fonts checked.

Also, bear in mind that changing the font would IS NOa T global setting, but rather a per session setting.


How can I gain access to my deceased relative's Instagram account?

Question: My uncle passed and my grandmother wants access to his pics on Instagram but his page is private. Is there any way I can gain access? I have visited many sites and have tried every hacking site known. I just need help to view his photos for my grandmother.
Comment: Have you contacted Instagram? I'm not sure what their policy is regarding deceased users. For what it's worth, this is why we all need to have a plan for our electronic selves.
Answer: Per their policy, you can't get login access to the account. However, you could try and ask for an archive of the photos.

8. HOW TO CONTACT US ABOUT A DECEASED USER
In the event of the death of an Instagram User, please contact us. We will usually conduct our communication via email; should we require any other information, we will contact you at the email address you have provided in your request.

Source.

How do I report a deceased person's account on Instagram?
It is our policy to remove the account of a deceased person from Instagram. To protect the privacy of people on Instagram, we are unable to provide anyone with login information to an account.
When you submit a report of a deceased person, we require proof of death such as a death certificate or obituary.

Source.


What are some good drawing programs to use with a ugee m708 on a macbook pro?

Question: i'm just another beginner who wants to get into digital art but got the tablet before anything else.
Comment: This is quite a broad question; people will have different ideas of what a "good" drawing program is, and which one works better with your tablet. Check [ask] if you want to know more.
Answer: I haven't ugee. In various web writings it's judged to be well usable for drawing. The tablet costs a fraction of the prices of high end models, so I guess you have no intention to shell out a fortune for programs. In this sense freeware can be recommended. You should learn to work as well with bitmap graphics as with vector, so get 2 programs.
Krita and MyPaint both are for bitmap graphics, Inkscape is for Vectors. For bitmap graphics there's also GIMP, but it'svery complex, It's plus is a big selection of available tutorials. The same can be said of Inkscape.
There are also several web based free services for vector and bitmap drawing. They are of course free only to some point, they cannot stay alive without money, so to get all available capablities  you must subscribe. They offer a possibility to start without installing anything.
I guess a majority of us have Adobe's programs. They have been around very long time and they cost some real money, so their development at least have a possibility to be well managed. It shows as quite coherent user interface and properties that professional users want. I guess it's a good idea to run at least the trial after you have gained some familiarity with free software.


How to upload .py file to new online Qiskit Notebook

Question: I'm trying to run a program in the Qiskit Notebook on the IBMQ Experience. I need to import some .py files that I've done in order to run my main program but the notebook won't accept .py files. I've tried uploading them (doesn't work, it loads forever) and also tried to write a .ipynb file and then change the name to .py but then the file disappeared.
Answer: The file editor only uploads, downloads and displays .ipynb files. However, you can create additional files using notebooks. To see that they are there, you can use the sys package.
You won't be able to import from local .py files, but you can open them as a text file and do something like eval their contents as a workaround.


Game of Thrones in Dublin

Question: I'm in Dublin today, and I would like to know if it's there's a way to visit the Game of Thrones Tv show locations without pay for the tour (70EUR). That is possible to make the GoT tour by myself? And if yes, is a good choice to do that?
Comment: Are you after the stock footage? Or the sound stages and sets?  All of the stock footage locations are accessible by private car, rail, and so on.
Comment: I would like an alternative tour since the official tour are not available on the dates that I'll stay in Dublin.
Comment: No problem, people have been touring the stock footage locations for years, even centuries before Game of Thrones was invented.  You just go...
Answer: The Dublin Winterfell tour is €55. They give out free cloaks and you even get to meet the real direwolves from seasons 1 and 2. See www.gameofthronestours.com.

Game of Thrones in Dublin


US economy stagnant growth

Question: Why US growth is stagnant even though unemployment is significantly low . Not only US but all developed nations are facing this problem. Is limited population the cause of this , I mean lower human resources.
Answer: Not necessarily. One has to distinguish between (output - I just assume that you mean output, i. e. gdp) growth and per capita growth.
In (very) simple terms: Growth is the result of either population growth, capital accumulation (more investment) or technological progress.
So one reason for the low US growth could be limited population growth and looking at the data this is a possibility (Population Growth Rate US)
Another possibility might be the "unusability" of technical progress. While a lot of research is done and we discover lots of new things not everything can be used in the production progress and is therefore not reflected in gdp growth.
One way to check this possibility is to development a new measure of technical progress - I think Daron Acemoglu and some coauthors are working on a new index. Another possibility is that this technical knowledge is just worthless. Consider the internet rush around 2000 which was at that time considered as technical progress which would increase the productivity of the whole economy... Well most of this was wrong and this technical progress did not lead to an increase in productivity - an argument often used by Robert Solow.
So the question: "Why is a nation not growing" is pretty difficult and not easy to answer or even understand.
Comment: Linked to the idea of "unusable" technical progress is "unmonetisable" technical progress.  If people used to buy encyclopaedias and software, and now use Wikipedia and open source, that implies a fall in GDP.
Comment: I recommend the [nobel prize lecture](https://www.nobelprize.org/nobel_prizes/economic-sciences/laureates/1993/north-lecture.html) by Douglass North to be more accurate. The result of his research is that the main source for growth is the appearence of new markets. There are a lot of reasons for new markets to appear: social, technical, political, wars, natural causes, etc and combinations of them.
Answer: Growth rates tend to fall down or become stagnant , once a country reaches certain stage of development. Developing countries have higher growth rater because they are catching up with the developed countries.
Answer: Possibly, eternal rapid growth is not possible.
Possibly, 1% growth in real GDP per capita (correcting for population size and inflation) is an achievement when you're already rich.
However, in the sense that some might expect growth to be slower, it can be pointed out that a large number of workers are not trained for post-industrial jobs, and this limits the possibility of the various companies in the economy to effectively deploy those available human resources. These workers may become "discouraged" (stop looking for work) not be counted among those actively seeking employment.
Also, there is an argument that rapidly reduced cost of leisure is causing many men to play video games (for example) and work less. If they are not actively seeking work, they are not counted as "unemployed".
Also, increasing industrial concentration tends to reduce competition, which negatively impacts the competitiveness of those firms internationally, thus negatively affecting both employment and growth (while positively impacting profits, at least in the short-run).
Other similar arguments are at times packaged together under "situations in which higher inequality is bad for growth".

US economy stagnant growth


Is there an RSS feed available for photos/albums posted by Facebook friends?

Question: There are RSS feeds for friends' Posts, Notes, and Statuses, but there doesn't appear to be one available for Photos/Albums. Does Facebook provide one, or is there another way to get an RSS feed for this?
Comment: I would think so, since Tweetdeck has a column where you can subscribe to new photos posted by your Facebook friends.
Comment: I hope you find your answer here.  I like how you originally asked on SuperUser: http://superuser.com/questions/11801/is-there-an-rss-feed-available-for-photos-albums-posted-by-facebook-friends
Answer: There is no publicly available RSS feed. Tweetdeck uses the Graph API to gather all photos from the user and updates the client based on new one received which aren't already in their database.
There IS a nice solution for Facebook Groups implemented using Yahoo Pipes (which seems to be old and no longer works). Possibly it can be modified to work with users. http://pipes.yahoo.com/pipes/pipe.info?_id=055b7fbcb01605dbd34e5287b8eee8cd
Comment: no it cannot be modified unfortunately, robots.txt disallows this.
Comment: Pipes is still under active development -- I'll check that pipe out, thanks.
Comment: @phwd: What do you mean it can't be modified. I was talking about the Yahoo Pipe I linked and you can clone it and change it however you like.

@arathorn: Pipes has been under "active" development for years. I wouldn't let that deter you from giving it a whirl.

I wrote a few thoughts about the platform's clout back in October 2009 if you're interested in reading. (http://nobulb.com/2009/10/has-yahoo-pipes-reached-its-potential/)
Comment: Sorry for the mixup I meant this part "Possibly it can be modified to work with users. " Been trying it the past week and I either get an error response or robots.txt message when trying to work it for users or albums.
Answer: There is Photo2RSS but its reported that it doesn't work always (haven't tried it though).


Is there an example of a classic aviation engineering moment when engineers had to discard all their work due to the wrong approach?

Question: Is there any classic aviation/space engineering moment where the engineers had been working on a concept for months and then realised that their approach to the problem wasn't quite right and so had to discard all their hard work and re-start from scratch? Please could you give some examples?
Comment: Do you count square windows on comet as an example?
Comment: @J... for a moment I thought "the F-35 isn't quite THAT old, is it?"
Comment: Langley, except he never got around to the re-start https://en.wikipedia.org/wiki/Samuel_Langley
Comment: There was a lot of that in the early years of aviation, pre-1900's.
Comment: @vasin1987 that wasn't a discard and start over thing.  It was simply stress calcs that were off for the corner radius used.  If thicker material/more rivets were used, it wouldn't have been a problem.
Comment: Nevermind months - how about [four decades](https://en.wikipedia.org/wiki/Moller_M400_Skycar)?  They still haven't gotten to the point where they realize it's a doomed idea...
Comment: @RonBeyer Please could you give some examples?
Comment: Well the DeHavilland Dash 8 was basically a do-over of the Dash 7, designed for a marketing concept that never materialized.  Only about 103 -7s were built, sold to operators that really needed its special capabilities.
Comment: @vasin1987 The Comet windows were not discarded, never mind the Comet itself. The Mk.4 had rounded corners to its windows and additional strengthening, it was a perfectly good aeroplane. (Its only problem was that while everybody was waiting, the Boeing 707 arrived).
Comment: I'm not sure if this meets your criteria, but would the Concorde/Tupolev (and later proposed-but-not-built supersonic passenger planes) fit the bill?  Might not count since some of these actually were in use for a while before they decided it was a bad idea and scrapped the programs.
Comment: The Space Shuttle program could partially match your criteria. It was discarded after the Challenger and Columbia accidents, although it somehow worked, although with a pretty high accident rate, even for space exploration.
Comment: To some extent, the whole trial and error process is based on discarding wrong approaches. Everything that's about experimentation falls into this start all over again principle. Most recent example is SpaceX's Starship development. (since you asked for aviation/space engineering)
Comment: @vasin1987: The Comet 1's windows actually weren't much squarer than airliner windows _today_ - the actual problem was that the builders used punch riveting (which is prolifically microcrack-producing) to attach the window frames, when the manufacturer's plans specified that they were to be glued in place (without using any rivets at all).
Answer: Supermarine Type 300
There are plenty of examples, but if you want a classic then perhaps the Supermarine Type 300 fits the bill. It began as a cleaned-up Type 224 but, as first presented to the Air Ministry, retained the Rolls-Royce engine with evaporative steam cooling and a straight, tapered wing with room for around four machine guns.
While it was still on the drawing-board the PV12 engine moved to glycol cooling and "Merlin" monicker, the Ministry requirement to eight guns and the wing to thinner profile and elliptical planform. Yeah, the Spitfire.
That famous D-section main wing box is in fact the legacy of the evaporative cooling system.
De Havilland DH 106
The world's first jetliner is pretty classic too. When de Havilland started work on a revolutionary idea of a jet-powered airliner, they turned to the German secrets being brought back from the aftermath of war. The airliner was to have a tailless swept wing. They built a quarter-scale aerodynamic test plane, the DH 108. It was fast all right, but it came at a time when nobody understood the sound barrier and all three examples shook to bits, killing their pilots. In part that gave the shape an undeserved bad name, but mainly DH realised that it did not have sufficient trim tolerance of varying CG position during commercial operations, and a tail would fix that. Enter the DH 106 Comet, the world's first commercial jetliner.
Convair F-102/106
Here's another almost as classic. When Convair first flew the prototype delta-winged jet interceptor the YF-102, it sucked. It handled like a pig on the approach and couldn't even go supersonic in level flight. Two new discoveries at that moment included area-ruling and conical leading-edge camber. Both were applied in somewhat ad hoc and hurried fashion to the YF-102A and it made Mach 1.25 in level flight, while also being a lot tamer on the landing flight path. Time for a breather and a proper job with 50% more thrust to boot, and the F-102B, renamed as the F-106A, happily hit M 2.3.
Fairey Rotodyne
And one more for luck. In the 1950s Fairey Aviation developed the Rotodyne, a VTOL feederliner with conventional wing and propellers but also a tipjet-driven rotor. Complicated and expensive yes, but what ended the project was the noise made by the prototype - its tipjets sounded like a thousand banshees coming in for the kill.
Comment: @FreeMan Rounding off the corners of the openings is hardly discarding all one's work. Far greater changes get made all the time. Many earlier aircraft had had rounded windows, they were nothing new. What changed was the increasing popularity of stressed-skin construction, where reducing stress concentrations matters more.
Comment: The DH Comet also had the benefit of square cornered windows which, unfortunately, led to stress concentration and hence, fuselage failure mid-flight. It led to a complete rethink of window shapes and the now ubiquitous rounded windows.
Answer: The original design for the 747 had a full double deck all the way down the fuselage (similar to the A380), but discovered that evacuating from the upper deck would have been difficult and dangerous. That design was scrapped, paving the way for the widebody 747 we know today.
Source: Joe Sutter, 747 chief design engineer
Comment: From the same book, the 314 Clipper used to have a traditional single tail. It went through the double outside plates to the final three during its test flights.
Answer: The first failed attempt by Rolls-Royce at using composite materials for jet engine fan blades, in the original RB211 engine design for the Lockheed L1011 TriStar, not only led to "discarding all the work" but bankruptcy and nationalization of the company in 1971.
There was no way that the contracts with Lockheed could be made profitable after changing to a conventional (metal) blade design, and the bankruptcy forced the cancellation of the original contract and re-negotiation of a new one.
The long term outcome was that the RB211 family of engine designs is still going strong (and is profitable) 50 years later - and the latest members of the family now have composite fan blades.
Comment: Yeah, and that mess took the Tristar with it.  Great airplane.  Talk about work for nothing.
Comment: Actually, the earlier Conway engine also had composite fan blades, at least in later versions.  That was entirely successful and used for many years in the VC-10 airliner.  It was when scaling the blade up for the RB211 that problems appeared.
Comment: It was a great plane. At least it lives on as a [gateway to space](https://en.wikipedia.org/wiki/Stargazer_(aircraft)).
Comment: Filing bankcruptcy in this case is a black belt business move.
Comment: @lalala and hey presto, they were nationalized by a Conservative government!
Answer: The Republic XF-84H "Thunderscreech" was an attempt to improve power responsiveness by using a turboprop to replace the turbojet in a transsonic upgrade to the subsonic F-84.
The supersonic tips of the propeller, however, made so much noise that ground crews became physically ill.  There were other problems, as well -- engine reliability issues and aerodynamic problems.  The airplane flew, but it never flew well, never set the propeller-powered speed records that had been expected of it, and never went into even limited production -- and further, supersonic tip propellers were abandoned industry-wide for three decades or so until "prop-fan" designs with highly swept blades were proposed and tested (but never adopted) for transport aircraft.
Comment: @leftaroundabout Lots of X-plane concepts were "what happens if" experiments.  Republic was pretty sure they could break Mach 1 on a propeller, and solve the slow throttle response of direct thrust turbines (by being able to almost instantly change pitch).  Whole concept out the window before first takeoff...
Comment: If you're going to count X-planes then this will become a _long_ list...
Comment: If I remember correctly, the TU-95 "Bear" patrol bomber of the Russians has supersonic propeller tips.
Comment: @CalinCeteras I've read that, too, though I think they're barely supersonic, and the bomber itself is firmly subsonic, as compared to the XF-84H which was high-subsonic and intended to fly supersonic, with significantly supersonic tips.  And the Bear is pretty danged loud, too...
Answer: Another example would be large passenger airships.  Lighter than air or heated gasses were the only means of providing enough vertical lift for reliable human flight until the first powered winged aircraft struggled into the air at the turn of the 20th century.
Airships benefitted from these new engines too, developing into skyscraper sized trans oceanic giants.
However as further improvements in propulsion made ever greater thrust available, the drag equation shifted more towards forward speed as well as lifting requirements (around 100 knots and beyond) in the 1930s. The large airships, with their draggy gasbags, became obsolete and were progressively replaced with flying boats, piston airliners, and jet airliners.
Issues with weather, similar to the Ever Given in the Suez canal (huge surface area becoming uncontrollable in high winds), also contributed to the end of their days.
Comment: Of course, the idea of passenger airships [isn't _quite_ dead](https://en.wikipedia.org/wiki/Hybrid_Air_Vehicles_Airlander_10).
Comment: This [one](https://en.m.wikipedia.org/wiki/Short_Scylla) might take up a bit less hanger space.
Comment: And this [one](https://en.m.wikipedia.org/wiki/Dornier_Do_X) might have done well with turboprops.
Comment: On a related note, the Hindenberg may qualify as a "oh bother... scrap it all and start from scratch" moment!
Answer: The famous B-52
When Boeing engineers designed the B-52, it was to have straight wings and propeller engines, just like its predecessors. When on one faithful Friday the time came for Chief engineer Ed Wells and and two of his fellow senior engineers to present the design to the Air Force, the USAF rejected the design and demanded a swept wing and jet engines instead. Ed and his team returned to Ed's hotel room, but not before having bought a block of balsa wood. Over the weekend they then proceeded to redesign the B-52 with swept wings and jet engines, inside Ed's hotel room, preparing a full report and a balsa scale model. They then returned the following Monday to the Air Force brass who, impressed by the effort, approved an initial order of 13 B-52 bombers.
Comment: That's wild. "We've spent months creating this design using proven techniques and carefully made the calculations to meet every one of your requirements." "No, that's no good." "Ok, then how about this model we slapped together over the weekend? Who knows if it works, but it looks really cool!" "Shut up and take our money!"
Comment: This is curious because usually it's the opposite: the military insist on a robust proven/working design (and quick!) instead of the new fancy risky stuff. Still, this was at the preliminary design stage, when such things happen routinely. Unlike B-52, several [T-10/Su-27](https://aviation.stackexchange.com/a/87724/13666) were already built and flying when the design was scrapped and started anew.
Answer: Depending on your criteria, this might qualify:
Airbus scrapped a concept, and redesigned it to make the A350. The original idea was to use A330 fuselage sections to create a competitor to Boeing 787, but after a number of bigger clients expressed their dissatisfaction  with the original approach, Airbus had no other choice than going back to the drawing board.
This may actually have been more of a management level mistake, rather than just the engineers getting sidetracked, but I bet engineers had their say when choosing the ill fated "lets whip up another 330" path was at hand.
Comment: Another Airbus example would be the wing of the A310 which was part of the British work share. Then Airbus Bremen presented their design and BAe had to retract theirs and, in order to keep face, the official story goes that they designed a new one which eerily resembled the Bremen design.
Answer: Sukhoi Su-27
The prototype T-10 was designed in the early 1970s as a direct response to F-15 (which was being finalised then). By the mid-70s it turned out that T-10 was underperforming and would lose to F-15 overall.
Mikhail Simonov, its chief designer, insisted on a new design (against a substantial government pressure). The new design, coded T-10C and which would become Su-27, had amost nothing to do with T-10 except for general principles: integral aerodynamic design, fly-by-wire with reduced/negative static stability, etc. As Simonov put it, only the main wheels and the ejection seat remained from T-10.
As a result, Su-27 will probably forever remain a pinnacle of aerodynamic design for agile piloted fighters.
Answer: In commercial aviation it's definitely the BD-5.    Jim Bede sold thousands of kits for this small sport plane, before he had a working engine.  There is a lot of history recorded about trying various small engines that would fail after a few hours.  Meanwhile he was selling more kits to fund his day to day operations, and eventually went bankrupt, leaving all the kit owners hanging.  Incomplete kits with no engine.  One to my dad in the mid 70's.
Some were completed, but the bulk of kits sold and contracted for never saw the light of day. Bede didn't now how to say no to a customer's money, even though he never had a viable engine.
https://en.wikipedia.org/wiki/Bede_BD-5
Comment: I would have to disagree. The early BD-5 design with the V-tail and composite construction was quickly discarded, but the redesign was successful and many thousands of kits were delivered, albeit without the engine, for reasons unrelated to the aircraft design. This is all widely documented.
Answer: A couple more candidates : the Avro Manchester deserves a mention. The (arguable) mistake was to make a heavy bomber as a twin engine aircraft, using bleeding edge 24 cylinder engines without the luxury of time to work out their reliability problems.
A relatively simple re-design with 4 reliable Merlin engines, readily available in mass production, gave us the Lancaster (saying anything more would be redundant). As such, the airframe engineers didn't lose much of their work, though the engine design didn't go any further.
Another candidate might not deserve to be on the list : the BAC TSR-2 of which Sir Sydney Camm said : "All modern aircraft have four dimensions: span, length, height and politics. TSR-2 simply got the first three right."
I would not agree that Concorde should be on the list because it entered production and served for decades; further sales simply didn't materialise. However you might consider the Boeing SST which started out as variable geometry, was re-designed as a Concorde-like delta wing, and then cancelled when two things became clear : like the TSR-2 and Concorde, it got the politics wrong, and the 747 was about to be a big winner.
Comment: Yes, it was Shackleton who axed the TSR2, but this was a Mach-2 Nuclear bomber: to drop bombs on...?  Same could have happened to Dyna Soar, able to cary a nuclear weapon, go down from orbit, re-start engine, and switch to a fully diffdrent orbit, a fully diferent destination. Simply, weapon of too much supremacy. Blessings +
Answer: When Theodore von Kármán was visiting, along with US Army officers, the German seized Aerodynamic research sites, German engineers were deported to the US, USSR, France,...he made an urgent call to his company headquarters in USA, indicating to discontinue all designs made for what later became the B-47, after watching results of sweptback wing, a concept spread in a High Speed Aerodynamics congress held in Italy in 1937. Blessings +
Answer: The one I know is the B-49 series .... to the XB 35 flying wing :
As far as I know were the control systems outdated and the machine became
an elephant to steer , in critical situations . Though many , many
improvements and with the ONLY technical systems they had , that time , even when it did reasonably well in the end :
EACH AND EVERY ONE of the XB 35 flying wing got scrapped , literally .
They built from their experience on , on the B2 spirit , though , so scrapping
a plan does not mean that the experience , made upon it , is also lost .
By the way , that happens all the time : from steam engines to diesel to
electric , ... nobody wants to heat up a locomotive in the morning for 5! hours anymore ... , just to start it up .
The final decision for the XB 35 flying wing seems the weight and complexity of the control
systems : nowadays make electronics the things much lighter and those
airplanes were designed for tomorrow but had the technology of the 40's .
Think about it for a moment : even the Liberty ships , that freed Europe
at the end of WW2 had TRIPLE EXPANSION STEAM engines . Diesel ?  - Existed ,
Double - Action Steam Engines ? - Existed .... so what I mean : sometimes
they are bold enough to do the opposite : taking a step back for several good reasons .
Here 's a video on the development of the B 49 / YB 49 and XB35 flying wing

LATER EDIT : some " numbers " for this extraordinary bomber , taken out of the book
" VLIEGTUIGEN " by Enzo Agelucci :
first , the text about the NORTHROP XB-35 FLYING WING ( 1947 , USA )
translated from dutch into english :
On the 25th of june , 1946 , the first flight was made with the " flying wing " , as Northrop calls this type of airplane without fuselage or tail .
That was the N9M , which was just a third in size , compared to the later XB-35 .
The test flights were satisfying and 3 prototypes of the bigger B-35 bomber got built . Already in 1941 , they began with the design .
As a result of technical difficulties , the XB-35 , which could carry
20 machine guns and a capacity of 41200 pounds of bombs , was not built in series production . Two of the prototypes got equiped later on , with jet engines but also these tests were not successfully .
Technical data ( the " green " pages out of the end of the book )
name : Northrop XB-35 Flying Wing .
built by : Northrop Corp. , USA .
type : bomber .
year of introduction : 1947 or later .
engines : 4 x Pratt and Whittney R-4360 jet turbines , each 3000 SAE HP .
wingspan : 172 Ft or 52.43 meters .
length : 53 Ft or 16.15 meters .
high : 20.0 Ft or 6.10meters .
empty mass : 89560 pounds or 40.624 Kgs .
maximum takeoff - mass : 209000 pounds or 94802 Kgs .
maximum speed : 391 miles/h or 629 kms/h .
cruising speed : 183 miles/h or 294 kms/h .
range : 10000 miles or 16100 kms .
crew : 9 brave guys .
The rather small cruising speed confirms : it steered like an elephant , maybe they got redundancy in some kind of way but
with all the heavy equipment and updates that added to this , the design specs were NOT met .
To be honest , if you drop 40000 ponds of bombs , you GOTTA get away FAST ;-)
Comment: There were only two XB-35s made; "each and every" is a tad misleading. You are probably thinking of the YB-35; around half a dozen were completed and several were then converted to jet power as the YB-49/YRB-49A. "Scrapped" is also an understatement; "Wilfully destroyed" is closer to the mark - the Smithsonian were even refused an example! Also, the B-2 can hardly be seen as a retread, stealth and fly-by-wire made it hole new ballgame.
Comment: Dear Guy , That is probably the best reason they got scrapped : even when you want to steer the airplane with hydraulics , is it a simple pump and electric valves that control the motion . The steering of it becomes totally electronic but back then they fed hydraulic lines all over the airplane . Hardly any redundancy over the controls was normal back then .
Comment: Even if you regard hydraulics as obsolescent by then (which is highly debatable), that does not make it "wrong". They "had the technology of the 40s" because they were designed and built in the 40s! That was right for their time, not wrong.
Comment: Dear Guy , I know that hydraulics can also be redundant but the fact is that all this mass must be taken into account . I also understand if they had 4-bit comparators that time , reliable enough , they would have introduced fly-by-wire much sooner . But THIS is the " design failure " category of the website . And the XB - 35 fits right into it . Yes , I have deeply respect for those engineers who built this massive airplane in a still much bigger challenge to be the first airplane of this kind  , no doubt . Being the first also means to BE the first to take punches for ( little ) mistakes .
Comment: These comments are for discussing your answer, not for repeating it. So far nobody is agreeing with you. Leave it at that.
Comment: A-380 is an example of wrong desing, its wingtip vortices, wake turbulence being so severe, it forces airports to stop traffic for several minutes, allowing for safe use of space by smaller airplanes, a Gulfstream sized Jet that entered the A-380 wake turbulence was so severely structurally damaged, that needed being scrapped. A-380, Antonov An-225 are the extreme class of wake turbulence of its own. But it was market, not engineers,who sent down this machine. Blessings +


lying Leg raises, hand under head

Question: While doing lying leg raises, I keep my hands under my head instead of keep them straight on the floor. I feel it puts more pressure on abdominal mussels. Will it have any side effect as I have not seen any one doing lying leg raises like this.
This posture is like this assume a person doing lying leg raises on floor, and he doesn't puts his hand near or under its hips but puts them under their head,
Comment: Possible to upload any pictures of yourself exercising? Or can you further elaborate the posture?
Comment: I think I get the exercise the OP is trying to depict - Lying leg raise, with hand behind the ears, head and shoulder off the ground like in crunches (although OP hasn't mentioned this part).

I came across this exercise in Jillian Micheals' Yoga Meltdown dvd. This version of lying leg raise makes me feel more on my lower back and abs than one with hands lying on floor near hips.
Comment: yes, I am talking about that
Answer: From my personal experience, daily I do leg raises but on a bench with hands holding head end of the bench (almost same as lying on floor).
I never felt it uncomfortable and there are no side effects AFAIK (I am doing it from quite a long time).
In fact, I felt it more comfortable than lying on floor version.
Comment: This is the same approach I use.  Legs are hanging off the bench so that I have to keep the abs engaged when the legs are at the bottom position.
Comment: @BerinLoritsch - Exactly. Legs hanging off completely engage lower abs and keep constant tension.
Answer: Keeping your hands by your side during leg raises (while lying on your back) or reverse crunches allows your hands to support your abs and that reduces the efficacy of the exercise.
Putting your hands behind your head allows only your abs muscles (along with your thigh muscles) to perform the exercises. This is much more effective; however, it's harder to perform.
As far as I know, there isn't any side effect to doing it that way and (assuming you use proper forms) you should feel the effect much better than supporting the abs muscles with your hands.

lying Leg raises, hand under head


Adding Text to a Web Part Page

Question: I'm working in a SharePoint 365 environment and created a web part page through SharePoint Designer 2013. When I edit the page online, the INSERT tab has options for Text, Image, App Part, and Web Part. Image, App Part, and Web Part are working properly, but the Text option is greyed out. Is there something I need to do to enable the addition of text to my page?
Answer: You can't exactly add text directly to a web part page.  You need to add a web part like the Content Editor Web Part, and then you can add text to it.  If you click on a web part zone, the insert text button should become active, but if you click it, it will just add a Content Editor Web Part for you.  Otherwise, you can just choose web part from the insert tab a choose a Content Editor Web Part (under the Media and Content folder).  Then you can insert text into the content editor (by clicking the link in the web part that says click here to insert content).
If you want to add text to a page without inserting a web part, you need to create a Wiki page.  Then in edit mode you can select any rich text area and the ribbon will display rich text editing controls.  Then you can type your text and save.
Joe
Comment: Unfortunately, when I navigate to the Media and Content folder, the only options I have are `Get started with your site`, `Image Viewer`, `Page Viewer`, and `Picture Library Slideshow Web Part`. Are there supposed to be more options here?
Comment: What access do you have on the site?  i.e. are you an owner? or SCA?  I would normally expect more web parts to be available than that, but it depends on what features you have enabled for the site/site collection?
Comment: Also, what site are you trying to do this on?  i.e. Custom Script is now disabled by default on the root site and any self service created sites (not created by an admin).
Comment: I'm the Owner, I created the site to test some customization features. When I do a Check Permissions on myself I see Full Control given by Owners Group; Edit through the Members Group; and under a label "The following factors also affect the level of access for this user" Deny - Add and Customize Pages
Comment: It appears you are correct, Custom Script is probably disabled. Thank you!

Adding Text to a Web Part Page


Covering containers of water

Question: In the Talmud (Chulin 10a), Chazal taught that one should not drink water, wine or milk from containers that were left uncovered because a snake and its venom might have gotten into the drink and it will cause the person danger. Today, snakes are not commonly found and the Matei Yehonoson 116:1 says there is a heter to drink from uncovered vessels if no snakes are around, adding that one may be lenient because at the time of the
halacha it was only made in a place where snakes were common.  Nevertheless, I know people who continue to be stringent on this practice, even covering their water glass between sips.  While I understand that poskim are stringent with regard to water left out overnight (see, e.g., Kitzur Shulchan Aruch 33:5), why should anyone need to be stringent during the course of a meal, when a snake would not likely crawl into a water goblet on a Shabbos table without notice?
Comment: Perhaps they are careful lest they leave the table and forget to cover it then? AFAIK the original takana did not involve covering if you were there to watch.
Comment: According to the GR"A, the danger of snakes is just one of many reasons Chazal had for that issur (see, for example, פאת השולחן הל' ארץ ישראל סי' ב' סכ"ה), so we have to follow their גזירות and תקנות even when the given reason isn't applicable.
Comment: (FWIW I've never heard of covering a glass while at the table.) Do you know that the people who do so do so for the reason of not drinking uncovered liquids?
Comment: @DoubleAA My rav told me he does it, lest everybody leaves the room.
Comment: @msh210, I believe the Steipler was stringent on this point.  I saw it by Rabbi Yehezkel Danziger (Art Scroll's Talmud editor), shlita, who did not impose the stringency on his guests, but accepted it for himself.
Comment: I once read that Rav Elyashiv was stringent to cover even the water for netilat yadayim in the morning. He said the same reason as user3445
Answer: Rivevos Ephraim 5:11 writes that in Sefer Halichos V'Hanahagos page 59 (Rav Eliyashiv) was Makpid to cover drinks. He brings a story were he covered his drink when he left the room for a second even with someone else there. He also brings a story which happened on Purim where he left room then came back and said don't drink the wine because it was left uncovered .see it inside.
Comment: This doesn't answer why anyone would be stringent in this regard.
Comment: Why is your answer in the second half of your comment?
Comment: The fact he was stringent shows there is something to it ,if you read the tshuvah he was afraid that nobody would watch it.
Comment: @sam what does it mean to "watch" the Rav's glass?  Does it mean that all of the guests have to constantly focus on the glass, doing nothing else, or can one assume that not even one person at the table would notice something strange crawling on the table?
Answer: Terumoth 8:4 implies that the drink would only have to be unobserved for a short time to be forbidden:

כַּמָּה יִשְׁהוּ וְיִהְיוּ אֲסוּרִין? כְּדֵי שֶׁיֵּצֵא הָרַחַשׁ מִמָּקוֹם קָרוֹב וְיִשְׁתֶּה:
How long must they be left [uncovered] for them to become forbidden? As long as [it would take] for a [creature] to come out from a nearby place and drink [from it].

According to the Yerushalmi (8:3), cited by the Rash MiSens, the amount of time allowed uncovered is very short, the "nearby place" including the handle of the vessel containing the fluid.
The Bavli (Chullin 10a) seems to only extend this allowable period slightly:

וכמה "מקום קרוב"? א"ר יצחק בריה דרב יהודה: כדי שיצא מתחת אוזן כלי וישתה
And how far away is considered a "nearby place"? Rav Yitzḥak son of Rav Yehuda said: [Even a period equivalent to] the time [necessary so] that it could emerge from beneath the handle of [the] vessel and drink.
ישתה" - הא קא חזי ליה? אלא ישתה ויחזור לחורו":
[The Gemara asks: If it is only the time necessary for the creature to emerge and] drink, doesn't one see [the creature drink, in which case there is no uncertainty]? Rather, [it is a period equivalent to the time necessary for a creature to emerge from a proximate place,] drink, and return to its hole. [If one left exposed liquid unattended for that interval, it is possible that the creature drank the liquid unseen by the owner of the liquid.]
Answer: Have you ever thought of snakes and their venom as people and their poisons?  Perhaps the stringency should remain in place, as although snakes in their reptile form are not as common as they once were, the poison of people, is evermore prevalent and all the more so, regarding politics and people of power and the possible covert demise of your adversary.  Kings often employed, tasters to taste their food and drink, in case a lethal poison had been introduced to their wine or water.  As far as I know, snakes don't even have affinity with liquid substances within jars, but people do.
Comment: A better example would be lead flakes falling from a painted ceiling into a water glass.
Comment: Not better - just another potential plausible cause of poisoning..
Answer: The Rambam brings this halacha in Hilchos Rotzeiach (chap 11:4), meaning that he believed that it was assur due to it being an actual sakana, and not for any ethical/mystical/spiritual reason. (Just as the gemarah in Chulin says - its a sakanah.
The  Shulchan Aruch does not bring down this halacha at all.
I would note that the germ theory of disease was not discovered until 1900.  At the time of Chazal and the Rishonim they knew that drinking water sometimes made people sick, but they did not know why. (See Dr.Chaim Soloveichic's Yayin Nesech Bemay Habanunim - thats why they drank so much wine - it did not make people sick).
In searching for a clue as to why it made people sick they assumed (based on the best scientific knowledge of their time) that it was due to a snake "o kyotze bo" that poisoned the liquid.
A Rationalist would use chazal's basic idea, ie. that its assur to do things that are dangerous (smoking, bungee jumping etc) but not necessarily be careful about the specific sakanah of uncovered liquid.  A non-rationalist, would be doing a "minhag chassidus" by following this rule.
ZevWrationalist
Comment: A rationalist might also follow the decrees of Chazal because that's how Halacha works...
Comment: The Shulchan Aruch actually quotes it in YD 116

Covering containers of water


Is there a word for a shared idiolect

Question: Is there a word for a shared idiolect or a dialect understood by only two people?
Comment: "Code", "secret language"? That's what we called it when I was a kid.
Answer: "cryptolect" or "cant" would fit.

cryptolect (linguistics) A secretive language form used by a subculture; an arcane cant.

A cant (or cryptolect) is the jargon or argot of a group, often implying its use to exclude or mislead people outside the group.

And there is "argot" also:

An argot is a secret language used by various groups — e.g. schoolmates, outlaws, colleagues, among many others — to prevent outsiders from understanding their conversations.
Comment: Very interesting! Thank you. This probably means there is no specific word for an 'argot/cryptolect/cant' used by exactly two people without any intention toward secrecy?
Comment: @Kinnard Hockenhull: We can consider two people a group also. And it is mentioned that an argot can be between schoolmates. So they can always be applied to two people.
Answer: The phrase secret language is commonly used.

Is there a word for a shared idiolect


Data scan not making sense for coco dataset

Question: I am doing a simple scan to see how dataset size affects training. Basically, I took 10% of the coco dataset and trained a yolov3 net (from scratch) to just look for people. Then I took 20% of the coco dataset and did the same thing.... all the way to 100%. What is strange is that all 9 nets are getting similar loss at the end (~7.5). I must be doing something wrong, right? I expected to see an exponential curve where loss started out high and assymptotically approached some value as the dataset increased to 100%. If it didn't approach a value (and still had a noticeable slope at 100%), then that meant more data could help my algorithm.
This is my .data file:
classes= 1
train = train-run-less.txt
valid = data/coco/5k.txt
names = data/humans.names
backup = backup
I am trying to train just one class (person) from the coco dataset. Something is not making sense, and in a sanity test, I discovered that the loss drops even if the training folder only contains 1 image (which doesnt even have people in it). I thought the way this worked was that it trained on the "train" images, then it tested the neural net on the "valid" images. How is it getting better at finding people in the "valid" images if it hasnt trained on a single one??
Basically I am trying to answer the question: "how much accuracy can I expect to gain as I increase the data?"
Answer:
What is strange is that all 9 nets are getting similar loss at the end (~7.5). I must be doing something wrong, right?

Yes, Please check the annotations file. Did you remove all the other classes except Person? What's the mAP of all those models?

"how much accuracy can I expect to gain as I increase the data?"

It's hard to tell but more the data(variation), better the model.


Bankroll for 1/2 NLH $200 Buy-In

Question: I heard the other day that to play 1/2 with a $200 buy-in that a bankroll of $200,000 is required. Is this accurate? Why or why not? I understand variance is a big reason for this, but any calculations or external resources are appreciated.
Answer: Wanted to comment on Clarko's answer but ended up too long so here's my own.
1,000 buyins is way too much. If you're making a good $15 per hour on 1/2, you're only making $12,000 after a year of playing (800 hours). This is 6% ROI, some banks almost give better returns.
My own recommendation is 20 buy ins. Since the buy in for some games is 200-300 BB, this is about $8,000. Some considerations:
- if your edge is good, you can consider lowering the requirement
- if your playstyle is more nitty, you can consider lowering the requirement as well. Note that good cash poker should be high aggression and variance, but if this is not your strong suit, then playing a higher stake with a nitty style may work.
- lower your stakes if you are on a downswing
The less capable you are of adjusting these things, the more bankroll you need to withstand variance.
Answer: This is not accurate for a 1/2 cash game, 1000 buy ins would be a very large bankroll. To be very safe, aim for around 100 buy ins for cash games. Just remember that the lower # of buy ins you have the higher your chance of going broke (assuming stakes do not change), no matter how good of a player you are. This is due to a phenomenon called gambler's ruin. Gambler's ruin basically states that if you play for a large number of games, you will always experience a downswing. Longer downswings have a lower probability, but having a larger bankroll and playing within your bankroll will protect yourself against these. Check out this link:
https://www.evpoker.org/article/gamblers-ruin.html

Bankroll for 1/2 NLH $200 Buy-In


Supernova explosion nearby

Question: A nearby star has crossed Chandrasekhar's limit. How do we come to know when it will undergo supernova explosion?
Or has it already undergone supernova explosion?
Comment: Not clear what you are asking. Can you clarify? If it has undergone a supernova explosion there wouldn't be a star there at all - except possibly a neutron star. If the core of a star exceeds the Chandrasekhar mass then a supernova is imminent - i.e. the core collapse in seconds and within minutes a supernova explosion is underway. If a white dwarf accretes mass beyond the Chandrasekhar limit it will explode (again within minutes) to leave behind nothing at all.
Answer: The Chandrasekhar limit applies only for white dwarfs. Stars on the main sequence (or even off the main sequence) can easily surpass it, but if a white dwarf's mass is greater than the Chandrasekhar limit ($1.39 M_{\odot}$), it will undergo some sort of collapse.
First, though, in response to

Or has it already undergone supernova explosion?

White dwarfs are not formed from supernovae, but from stars that (relatively) gently shed their outer layers to form planetary nebulae. So no, the stellar remnant will not have gone supernova already.
Back to the main question. If a white dwarf exists, its mass is less than the Chandrasekhar limit. To surpass that, it needs to gain mass. This can happen in binary systems where the white dwarf accretes matter from the more massive star (generally a giant). The white dwarf can then undergo a Type Ia supernova and explode. The light curve will look a bit like this:

A second (but far less likely) scenario is that two white dwarfs merge. The result? A Type Ia supernova and, possibly, a neutron star.
Answer: The Chandrasekhar limit in general does not pertain to the mass of the star as a whole. It addresses the mass of the degenerate core. It's only in white dwarfs where the Chandrasekhar limit applies to the mass of white dwarf as a whole, but that's because white dwarfs are almost entirely degenerate matter.
Consider a 1.6 solar mass that is not a member of a multiple star system. Even though this star's total mass exceeds the Chandrasekhar limit, this star will never go supernova. This star will instead live for billions of year on the main sequence, then a bit longer as a post-main sequence star, and finally end it's life as a white dwarf with considerably less mass than that original 1.6 solar masses (and considerably less than Chandrasekhar limit).
The star leaves the main sequence when it burns all of the hydrogen in its core. Two things happen at this point. One is that it starts burning hydrogen in a shell around an inert core of helium. The other is that it expands into a red giant. (Note: Some people are taught that a star becomes a red giant when it starts burning helium. This is not the case. This post-main sequence star is a red giant that is not yet burning helium.)
That inert core of helium increases in mass as hydrogen shell burning proceeds. A funny thing begins to happen with this increase in mass: The inert core becomes degenerate. An even funnier thing happens next: Adding even more mass makes the degenerate core shrink in size. The star is poised on the next phase of its evolution, which is helium burning. The formerly inert, degenerate core of helium is no longer inert or degenerate at this stage. Think of this phase of a star's life as a main sequence helium burning star. It's definitely not on the main sequence, but much of the physics is the same. One thing that is different: The shell burning of hydrogen is still occurring.
This phase doesn't last long. The star will soon consume all of the helium in its core. At this point, the star becomes a red giant for a second time. This is the asymptotic red giant branch. The star has an inert core of carbon and oxygen surrounded by a shell of fusing helium, which in turn is surrounded by a shell of fusing hydrogen.
These end of life convulsions are not good for the stuff that surrounds the shell of fusing hydrogen. The star expels a lot of that gas into nearby space. Eventually it will expel most of the burning shells of hydrogen and helium, leaving an inert, degenerate core of mostly carbon and oxygen. This is a white dwarf. A planetary nebula of expelled gases surrounds the white dwarf. The white dwarf itself has but a fraction of the star's initial mass. Most of the mass is in that planetary nebula.
Larger stars are even more proficient at expelling mass than was this 1.6 solar mass star. For stars with an initial mass of about eight solar masses or less, the white dwarfs left behind at the end of the stars' lives will be less than the Chandrasekhar limit.
The fate of stars over ten solar masses is much more violent. At the end of their lives, they have lurking inside them a series of burning shells that surround an inert, degenerate core of iron. A star has about five days to live once that core of iron starts forming. That's about how long it takes to create (from scratch) a degenerate iron core that approaches the Chandrasekhar limit. At or near the limit, the core starts to collapse, and the star forms a type II supernova.
A white dwarf can form a type Ia supernova with a little help from a binary neighbor from which the white dwarf is stealing mass. Conditions have to be just right for this to happen, but when it does, the white dwarf can gradually accumulate mass and go supernova. Since white dwarfs have expelled all of their hydrogen, there won't be any signatures of hydrogen in the supernova explosion. In fact, it's the lack or presence of hydrogen in the supernova signature that distinguishes type I from type II supernova.

Supernova explosion nearby


Login in issues - front end

Question: I have had some sporadic issues in my time with EE where a user just cannot login to the front end, it seems to be a case of initially it validates the login details, routes you to the intended page, and then by the time the user gets there, they are logged out and dealt with accordingly. I have had it myself, so i know its effected browsers that are fine of config, and passwords etc all correct.
I am now however experiencing the issue with a very important user, everything works for everyone else in every environment, and works in this case for the user in everyone but one browser (but the browser is not the problem)
Am sorry for the broadness of the question, it is finger in the air because that is exactly how i find it when it comes around. Am just hoping someone out there has experienced the same, and has an understanding of it that i have not managed to nail it to.
Have cleared caches both our end and theirs - in the past this has been the place to start.
Answer: Have you tried this suggestion from @Anna_MediaGirl?

Login in issues - front end


Apache 2 WebDAV, server trash folder?

Question: I've just started experimenting with WebDAV under Apache 2.2 on CentOS 5. It works well although the Windows WebDAV client is clunky and nowhere near as seamless as it should be.
When a user deletes a file through WebDAV, is there a way to have it moved to a specified folder on the server rather than deleted?
So you could setup a sort of trash folder so that anything deleted could be recoverable by an admin with server access?
Answer: There is no native functionality like this. I'd recommend just using some sort of incremental backup script like rsnapshot or rdiff-backup. Either of these will maintain a GFS, incremental backup rotation for you, and can keep backup copies locally or on a remote host.

Apache 2 WebDAV, server trash folder?


Can two neighboring galaxies move apart at steady speed?

Question: While I was trying to understand the three models that obey Friedmann's two assumptions of a non-static universe, I came across a line that says and I quote "It (referring to Big Bang) starts at time zero and eventually the galaxies are moving apart at steady speed." The question is - is it possible for two massive space bodies to move apart at a 'constant' speed? What do you say on account of the gravitational forces acting between the galaxies? And does it mean the universe will only expand and never come to rest? P.S. I am assuming 'steady' to mean 'constant'.
Answer: The key word here is "eventually."
The strength of the gravitation felt between two objects is inversely proportional to the square of the distance between the two bodies. As a result of this, raising an object from a nonzero distance from object A to an infinite distance from object A requires a finite amount of energy.
In a Keplerian/Newtonian trajectory, the velocity of an object solely under the influence of gravity is governed by an exchange between gravitational potential energy, and kinetic energy.  As a result of that, no matter how long their mutual gravity acts, there's a limit to how much kinetic energy gravitation can take from the object.
If the equations are balanced such that the object would come to rest at an infinite distance, the speed that the object has is called "Escape Velocity."
If the object is moving faster than escape velocity, it would wind up with a finite relative velocity at an infinite distance, and this value is called Hyperbolic Excess Velocity.
For instance, if the Sun and Voyager I were the only objects in the universe, and there were no other forces between them other than mutual gravity, the relative velocity between the two of them would never fall below 16.6 km/s.
A similar case holds for any two objects, regardless of mass; If they're moving relative to each other higher than their mutual escape velocity, considering only the  two bodies, and only the gravitation between them they wind up asymptotically approaching a finite relative velocity.


Is it possible to get from Canada to Greenland by road or ferry?

Question: Are there any roads (or ferry service) that would allow a person to travel from Canada to Greenland without taking a plane?
Comment: Get a Jeep or something and drive over the ice from Ellesmere Island (Canada) to Etah (Greenland);-P Not sure how thick the ice is though (or other practicalities of driving around there in a 4WD), but that's the route some of the Inuit took in the past to get to Greenland, [according to Wikipedia](https://en.wikipedia.org/wiki/Etah%2C_Greenland).
Answer: The Greenland tourist board says No.

There are no ferry connections between Greenland and Iceland, Denmark or Canada. However, more and more cruise shipping companies are choosing to include Greenland on their itineraries, whereby it is possible to begin the voyage from Iceland or go onboard at, for example, Kangerlussuaq.

Greenland being an island, I hope it is obvious that there are no roads linking it to a continent. While theoretically the sea freezes, the ice is not traversable by anyone other than a well-prepared team equipped for arctic exploration.
Comment: @Vince Thanks for the edit, but actually "[There are no roads](http://travel.stackexchange.com/questions/7628/can-you-actually-do-a-road-trip-in-greenland?rq=1)" is a fairly accurate summary of the situation.


Custom Heroku Domain redirecting to random website

Question: I'm helping a friend out with her Rails App, and this morning the custom domain started automatically redirecting to freelancer.com instead of the App. The automatically created Heroku subdomain, i.e. 'randomapp.herokuapp.com' is still working fine without any issue. No new changes have been pushed to the Heroku repo for approximately a week, and the custom domain worked fine for months - until this morning. Were we hacked? Maybe a problem with the DNS?  Any insight is greatly appreciated as I'm not particularly well versed in this.
Comment: What are your DNS entries??
Comment: Is this what you are referring to?

www.resilientapp.com
Server:  22.214.171.124
Address: 188.8.131.52#53

Non-authoritative answer:
Name: www.resilientapp.com
Address: 188.8.131.52
Comment: Okay. 188.8.131.52 is ec2-184-73-235-153.compute-1.amazonaws.com. Do you have a site there (Amazon)?? If so, check to see if there is an .htaccess file in the web root directory. I do not know how Heroku works, but I seem to remember a similar issue asked here sometime back.
Comment: Looking at: https://devcenter.heroku.com/articles/custom-domains you need to have a domain name defined at Heroku and a CNAME record pointing your domain name and www to your Heroku sub-domain. When I do a *dig www.resilientapp.com any* I get an IP address and not a CNAME. You may need to go through your original Heroku set-up and re-do some of it as well as check your DNS records. Your DNS records may be hosted with your domain registrar so you may need to log on there to see your DNS records.
Answer: This sounds like an DNS zone file issue which you will need to take up with your DNS provider.
If the CNAME record where replaced with an A record as seems to be the case based on the comments then the connection would no longer to go Heroku, it would instead go to the server with that IP address (which as has been mentioned in comments is an AWS EC2 instance (virtual server). In this case the settings on Heroku are unlikely to be at fault. If the settings on Heroku where the issue then connecting to the domain would just give some general server error, or perhaps a Heroku specific error page, but it wouldn't connect to an alternate server. Whether you where hacked or whether there was a glitch with your DNS provider is unclear based on what you are saying.
The other issue that may have occurred is that the domain may have expired without being renewed. If that happened then someone else could have swooped in and bought it (a very common business model online) and mapped it to their server's IP in order to direct all traffic that used to be going to your site to their site in an attempt to get more traffic and perhaps more business.
The two steps you should take are to check your domain name is still registered, has not expired, and is still owned by you, after which then check with your DNS provider and check the zone file records to see if the records are correct or not and the correct CNAME record is pointing to Heroku.


How to tackle a huge bug backlog?

Question:
What is the best approach in dealing with a huge bug backlog? Currently we have a huge bug backlog and i was looking for an efficient way to deal/categorize/ how to manage the backlog?
Answer: This is very common.
There are basically 3 parts to the problem:

Measure.
  Track stats to know when the backlog is getting worse or improving, week to week
Identify.
  Figure out what things you need to change to stop making it worse week to week
Cleanup.
  Clean up the backlog you created, bit by bit

I'll focus on part 3 - the cleanup - but if you don't do parts 1 and 2 you'll quickly be in a bad spot again (if you ever get out at all).  If you want more info on Measure and Track then ask questions about those parts specifically for specific answers that can go into detail (and solicit a variety of answers of course).  Also Kate's detailed answer has good info for those activities.
More specifically, for the cleanup, I would look to

Prioritize.  They can't all the the same priority.  Maybe rank into High, Medium, Low.
Estimate difficulty.  In terms of relative complexity to other tickets.  Using points and voting is one approach.
Categorize, Tag and Label.  Some tickets are minor, say layout issues, others might be significant, maybe database issues.  Creating categories and using tags and labels can help in triage.
Use an Agile approach focused on this weeks (or this sprints) work.
Use Big monitors to show the backlog constantly.
Use a tool like Jira, Trello or Pivotal Tracker to manage the tickets.
Mix current development tickets with ones from the backlog.
Delete old tickets.  Even "a good idea", "we should do" will often not be done.  Be bold in your deletions.  You can always recreate or revive tickets
Write tests.  If you have accumulated a lot of bugs, are folks writing tests to prevent them in the first place with TDD/BDD ?  If not they should start now to prevent the bugs increasing.
Use QA/QE to help test for, find, prioritize and categorize bugs
Review the amount of work assigned to, done and overflowing from sprint to sprint and see if you are simply taking on too much work.
Bring the issue up in retrospectives to get more ideas on how the team would like to address it.
Think short term and what resources would it take to actually address it right now compared to those available and current feature development
Think long term about how to avoid getting back in the same situation.  Stats on tickets (added, resolved, outstanding, etc.) and the trends week to week should be monitored.  Long-term thinking should include analysis of how things got the way they are right now.
Comment: Good answer. The only thing I would add is to spend some time finding out why you have all these bugs. Are there process issues? Education issues? Clarity issues? Staffing issues? "Huge bug backlog" is a symptom of a problem somewhere.
Comment: @mademoiselle If the backlog is out of control despite having measures in place and working on solving the bugs, this is possibly a sign that the team is taking on too much too fast. Your retrospective each sprint should be the moment where you note that the backlog of bugs is increasing faster than it can be managed even though development is continuing. There could be any number of reasons for this, so an analysis needs to be done on how the situation came about, how it should be dealt with (short term), how it will be mitigated (medium term) and how it will be prevented (long term).
Comment: @JoeStrazzere That was my thought exactly. A large bug backlog is not a problem. It's a symptom.
Comment: @JoeStrazzere - agreed. I expanded on that in another answer that's more focused on process/environment than Michael's excellent answer.
Comment: Thank you for responding, currently we work in an agile scrum environment and we dedicate a percentage of our sprint to fixing bugs, however the backlog is out of control. We are using Jira.
Comment: @Cronax good point, I added a point about that.
Comment: Yup, I agree with both of you.
Answer: In addition to Michael Durrant's excellent answer and the equally good comments, I'd suggest you consider a few things:

If you have not already done so, devote some time to analysis of your bug backlog. You will probably find some combination of the following things:

The bugs cluster in certain areas of the application. These will typically be the areas that are most complex and/or had the least design and architectural attention.
A significant number of bugs are caused by insufficiently defined user stories or missed user stories.
A significant number of bugs are in areas that are not unit tested or unit-testable.
A significant number of bugs are regressions of previously tested functionality (which is probably not tested by automation or not testable by automation).

Once you have a decent analysis of your bugs, you will find that they point to a number of areas where your process need to improve. For example:

If a lot of your bugs are customer-reported, your team probably needs to devote more time to integration and end-to-end automation, starting in the parts of the application where customer-reported bugs are thickest.
If a lot of your bugs are regressions, your team probably needs to devote more time to building good unit and integration tests and maintaining them as functionality changes.
If a lot of your bugs are obsolete (that is, have been fixed in later versions but were never closed) or duplicates, your team probably needs to spend more time grooming your bug backlog along with the feature and user story backlogs, as well as aggressively hunting duplicate reports.

When you have an idea why your bug backlog keeps growing, where they're coming from, and the root causes of them, your team may need to designate a sprint as a bug cleanup sprint, where you start with the highest priority bugs and work your way through the bug backlog.
For a really horrible bug backlog, you might want to designate every fourth sprint (or whatever cadence suits you) to bug cleanup until the backlog is under control.
If insufficient unit/integration/end-to-end test automation is part of the problem, you may want to devote one or more sprints to fixing the test automation.
If you are not able to devote sprints to automation or bug cleanup, then chances are the problem is higher up the food chain than your team and needs to be addressed with your management - a team that is not able to spend the time they need on quality practices or reducing their technical debt (which your bug backlog represents) is typically being pushed or required by their management to produce more new functionality than is sustainable (in which case I sympathize. I've been there, and educating management is not fun).
Comment: Another thing you may find is that a significant number of bugs are actually symptoms of a single underlying issue.  I once fixed a single bug in some window-management code, and closed two dozen bug reports about minor user-interface annoyances.
Comment: +1. [80-20 rule](https://en.wikipedia.org/wiki/Pareto_principle) says that 80% of the problems come from 20% of the causes - you need to identify that 20%
Comment: Plus uno Kate, 'specially the last point!
Comment: +1. The last point is really the hard one, the worst is when the management are a part of technical people that always done things like this.Iit'll work'., the only answer i always got on my previous job.
Comment: @Walfrat - been there. It's ugly. When management started as a handful of guys in a room throwing code around they can have issues realizing that this *doesn't scale* and won't work for a company with 30 programmers. Not at that job anymore, thankfully.
Answer: When I have worked on resolving bug reports in the past I found that the backlog was able to be shrunk due to a large number of people reporting the same bug. We wrote a similar bugs plugin for our app which searched all open bugs and recommended which ones to link as the same bug, then a new bug report was created automatically with details from all the customer submitted bug reports and the customer submitted bugs which where for the same bug where all linked together and related to the one bug, in one instance we where able to take nearly 1000 bug reports and reduce them to a single master bug report which had been duplicated so many times simply because the bug was in a frequently used feature which was bringing up an error display and our error display featured a "Report as Bug" button.
Answer: Big long lists of bugs are a waste of time. Bugs will become harder and harder to reproduce while you are going over the list over and over again. I once had a list of 3000+ defects, with no end in sight.
I will suggest something radical. Throw all the defects away and introduce a zero-bug policy.

Now when a new defect comes in:

Triage it according to the policy. Fix critical stuff now, regular bugs after your current work. Decide if all others are features, improvements or trivial's. Only place them on a backlog if it is really worth it in the next period. Communicate clearly to the reporter.
When fixed do a root-cause analysis and tackle places where bugs are created. Improve the process and the code-base.

The Agile team should try to keep fixing all bugs as soon as possible. It lowers their velocity, which now becomes honest, due to past mistakes new features will come out slower. Inspect and adapt your planning with this new knowledge.
Answer: Faults are an inevitable part of software delivery. I only briefing touched on managing lists of faults in Agile Project Execution so it is well worth expanding on.
In fact defects is an area where software delivery, including agile software development, can get messy. Luckily there are ways to manage this mess or to avoid it altogether. Jo's question hints at potential answers but there are others. In fact I know of at least nine common strategies for managing a growing fault list.
My strategies are:
<code>Do nothing
Filter out the noise
Stop logging low impact defects
Close off low impact defects
Prune the backlog
Batch the defects
Blitz the defects
Fix some every sprint
Automate the tests
</code>

Do Nothing

Before deciding which option to take you've got to know who cares. Who cares that the product backlog is large? Product Owner? Developers? Project Manager? If nobody cares then it isn't a problem.

Filter out the noise

Then there is, why do they care? Maybe your developers care because they see a lot of noise in the product backlog, things that they shouldn't be working on. If that is the problem then just make sure the developers don't see the low impact items until those items get prioritised. If your product backlog is electronic then you can use some kind of filtering for this. If the product backlog is cards on a wall, then put the non-prioritised cards somewhere else.
It might be your product owner who hates wading through low value defects when they prioritise the backlog. Filtering can help here too.
Maybe the tester cares because it makes the fault statistics look bad. In that case check where these figures are being reported and see if any anybody else cares. If the higher ups don't care then persuade your tester not to care. Alternatively negotiate reporting something else, e.g. only high and medium impact defects and exclude low defects, or report number of defects in each category. This is also essentially a filtering solution.

Stop logging low impact defects

If you have to do something to reduce the number of defects on the list then you can, as Jo suggests, just stop logging low impact bugs. The only trouble with ignoring low impact defects in this way is that throwing the card away doesn't fix the problem. There is a risk that people will keep noticing the same faults and raising them again. None-the-less you might find that risk worthwhile.

Close off low impact defects

This is a bit similar to not logging low impact defects at all. In this case you don't fix the problem but decide it is never going to be fixed and just close the ticket. Same risk that it'll be raised again, but might not matter.

Prune the backlog

Even if you retain the full list of defects you'll have to prune the product backlog occasionally as the list will become stale. Over time, because of changes to the system, some items will become irrelevant. Irrelevant defects are just clutter and should be purged.

Batch the defects

Another option is to batch related defects together. They might be low impact and low value individually but in combination their overall value will increase. For example you might group together a set of "email" defects and get the product owner to priortise these grouping rather than the individual items.

Blitz the defects

A common tactic is to blitz the defects. That means allocating the whole team to fixing defects for a sprint. This often happens immediately before a major launch.

Fix some every sprint

It is also common to allocate a certain proportion of effort to fixing faults each sprint. I advocate giving the technical team time each sprint to fix technical debt and fixing faults can be rolled into that.

Automate the tests

The last and best of the nine strategies is to push automated testing. The goal with automated testing is that all defects are addressed within the sprint thus the number of defects that need to be logged are vastly reduced. And the step of logging the defect can be often replaced by writing a new test.
Answer: If you don't have a big backlog then you don't need to deal with it. I think to manage what you have currently, in addition to all the good points already presented to you by others, you have to figure out the phase(s) most defects are injected too.
In my understanding of the Agile theory, defects are technical debt, you don't really allocate time in a sprint to work on technical debt. Each sprint has a clear goal -- working on stories. I know in reality teams may allocate resource on the side to tackle on technical debt, but this means it should at the same time take away resource from the sprint (lower velocity), and this is rightly so to avoid more defects injected due to lack of proper resource/time.
From my experience, unless your backlog is from legacy code (days before being Agile), you should look at your "done criteria" for your Agile stories. When a story is done, it should be "done done", not just code written ready for QA. If too many defects come our of these story, you should make sure necessary testing is in the storys' done criteria. Hopefully your backlog will shrink this way.
Answer: In "Perfect Software and other illusions about testing" Gerald Weinberg proposes declaring a "bug-amnesty:

Remove all bugs from the bug database and send a notice to all issuers telling them to resubmit a bug if they're still concerned about it. […] When I did this with the 14,000-bug database, the reduction was enormous and the problem was solved.

How to tackle a huge bug backlog?


Experience point calculation for encounters

Question: I am likely missing something very obvious but I cannot find a reliable way to figure out how much XP to give my players for encounters anywhere, currently I'm using a factor of 5 encounters of a single characters level is exactly enough for them to level.
Comment: It's in the DMG. The information is explicitly not in the SRD, since it's not OGL. Don't have access to the book right now, so I don't know what page specifically.
Comment: Do you have a DMG or are you using just the SRD?
Answer: There are online encounter calculators that do the work for you. The actual number of CR-appropriate encounters necessary to level up is 13.3.
Comment: Thank you, I use dndwiki.com entirely for information and thus is the only other site relevant to  dnd I can access easily
Answer: You can calculate the x.p. gained yourself
This is a formula that gives out the x.p. gained by one character for defeating a given monster. CR ist the Challenge Rating of the monster. Number of party members includes allies who have participated in the encounter.
\$ \dfrac{\left(300 \times \text{character level} \times 2^{(\text{CR - character level}) \times 0.5}\right)}{\text{number of party members}} \$
Half of the results of this formula are identical to the offical table, the rest is close.
You can generate a spreadsheet by copying the following line into the first cell: <code>=ROUND(($A2*300)*2^((B$1-$A2)*0,5); -1)</code>
The table you get by this means has the CR in the columns and the character level in the rows.
If you feel uncomfortable with such a complicated formula, the following procedure gives out roughly the same result:

Multiply the character level with 300.
For each step that the CR of the monster is above the character level, multiply the result with 1,42, repeating the process several times if necessary. For each step that the CR of the monster is below the character level, divide by 1,42.
Divide the result by the number of party members plus allies.

What you get are the x.p. gained by one character for defeating one certain monster.
There is one major exception: If CR and character level differ by more than 7 the x.p. given is at the DM's discretion only. By defeating weak monsters the PC's should normally not gain any experience, defeating monsters of CR 8 steps above their character level should be impossible in most cases, so how much experience is given out is not a mechanical question.
There two minor exceptions: the values given for CR 1 are lowered in the official table, character levels 1-3 have a single line, which mostly follows the numbers of character level 3.
Effects of the formula:

If the party is comprised of several characters of different levels, the x.p. gained by each character differs.
Higher-leveling characters get less x.p. from an encounter than low-leveling characters.
For each two steps the CR rises, the x.p. double, and vice versa.
Comment: What does the 0,5 represent?
Comment: This is a pretty close approximation, like using sqrt(2) instead of 4/3 for odd and 3/2 for even (what the tables actually use). This makes the even levels a bit less friendly, but also makes the non-matching awards more accurate.
Comment: might put a spread sheet equivalent in there, like

=ROUND(((300*$A2)*2^((B$1-$A2)*0.5)), 0)

where A is the level column and 1 is the CR row
Comment: Thank you - I have edited most of your hints in - but I still do not understand the 4/3 and 3/2 rule you mentioned, though I see the differences in my table and the official table.
Comment: my bad, was thinking of the pf tables. They increase at 4/3 and 3/2, instead of sqrt(2), where they are the same for odd levels.
Answer:
currently I'm using a factor of 5 encounters of a single characters level is exactly enough for them to level

According to the DMG, 75xp per level for a given encounter should equate to ~13.33 encounters per level (which correlates with the PHB progression; where level * 1000 additional xp is required to achieve the next level.)
If you wish to use a factor of 5 encounters per level instead, then you need to multiply the award by 13.33 / 5, or 2.66. To achieve that rate, you should be rewarding 200 xp per level to each player per encounter.
Alternatively, you could lower the progression requirements to level * 376 additional xp for the next level, but the math is probably easier to adjust the individual encounter reward to 200 xp per level.
I should add, however, this will also affect the wealth gain, meaning, if you award the standard treasure per encounter, pretty soon your players will have less than anticipated wealth, which can significantly lower their odds for a given Encounter Level. Thus those awards would also need to be increased by the same factor; 2.66. If you look at table 3-3 in the DMG, that's what I'm referring to. Each encounter should yield that value * 2.66. That table (and most others) are also written with parties of 4 in mind, so if your group is not 4 players, you need to take that into account too.
The standard 13.33 encounters per level is a bit fast (it's the fastest progression listed for Pathfinder, along with "medium" at 20 and "slow" at 30, if I recall correctly.) If you are using any commercial adventures, and you are using 5 encounters to level, your players will likely level before they are able to complete significant parts of the adventure, possibly making the remaining encounters much more trivial and anti-climactic. In the end, the bookkeeping of experience, treasure and level gain will be much simpler if you use the DMG tables.
Having said that, I use the UA Variant, Level-Independent XP Awards. I also have a spreadsheet with number of party members and levels, treasure, experience awards and advancement tables, so I can tweak one number and it modifies all the tables.