Daily Archives: 2013-04-15

Software Development Is Bad For Your Health (And What You Can Do About It)

中枪了=。= 学习之。

译文:编程是一种对你的身体健康十分有害的工作

Embedded Keywords for searching: 坐姿,脊椎,久坐


Software Development Is Bad For Your Health (And What You Can Do About It)

February 24, 2013 alexmedearis

Software Development Is Bad For Your Health_1

Slouched Sitting Posture

If you’re like most computer programmers, this is probably what you look like for a large portion of the day, hunched over your desk at a computer for hours on end.  It sucks.  I know because I’ve been there.

The head is forward (1), shoulders are slouched (2), back is arched (3) and your hips form an angle of less than 90 degrees (4).  The evidence is overwhelming that sitting this way is really bad for you. Slouching can cause problems with headaches and jaw pain , gastrointestinal problems , give you a beer gut , even cause you to perform poorly at your job and wreak havoc on your perceived confidence.  In order to avoid these problems, a number of experts advise improving your sitting posture.

Software Development Is Bad For Your Health_2

Proper Sitting Posture

This what the textbook “correct” sitting posture looks like.  The monitor is positioned at or just below eye level so that the head is straight (1).  The shoulders are back and the back is slightly arched (2).  The elbows form a 90-degree angle (3) so that the forearms are level.

It’s true that sitting properly may improve your overall posture, but it’s only part of the story.  For me, the improvement was marginal at best.  I still walked around with slouched shoulders and with my head forward.  About a year ago, I made a concerted effort to change that.

The Beginning

I’ve always struggled with posture.  It doesn’t help that I’m tall and lanky, which seems to exacerbate the issue.  So, last April, when I was offered a free personal training session as part of my new gym membership, I took it as an opportunity to learn more about posture and training.

At the first session, the trainer puts you through a series of exercises to try and determine overall fitness and if there might be any areas which need improvement.  Even though I would consider myself a relatively fit individual, I had trouble with exercises focusing on the abs and glutes.  Why?

The Kinetic Chain

In physical therapy, there is a concept known as a kinetic chain .  Essentially, the idea is that no joint can be evaluated in isolation.  The body tends to compensate for injuries or muscle imbalances in one area by propagating the imbalance to other muscles and joints.  An imbalance in the hip will propagate to the back and shoulders, for instance.

Software Development Is Bad For Your Health_3

Kinetic Chain Ripple Effect

In my case, I believe I developed a muscle imbalance in the hip resulting from hours sitting at a computer.  When you are sitting, your abdominal muscles are not being engaged .  Furthermore, the hip flexor muscles are contracted which can shorten them over time .

With shortened hip flexors and weak abs and glues, the result is an excessive anterior pelvic tilt, meaning that the hips are excessively tilted forward. Some amount of anterior tilt is normal, and the back naturally has some degree of arch, between 4-7 degrees in men and about 7-10 degrees in women.  Mine was closer to 15 degrees.  The anterior pelvic tilt propagates up the kinetic chain, resulting an excessive back arch.  The excessive back arch means that the shoulders and head must come forward to compensate.

Software Development Is Bad For Your Health_4

Anterior Pelvic Tilt

Regardless of whether you are sitting with proper posture or slouching, you will still run into these problems.  Of course, sitting properly will help, but it may not be a solution in itself – at least, it wasn’t enough for me.

My Results

The solution for an anterior pelvic tilt is actually fairly straightforward in theory – strengthen the abs and glutes and stretch the opposing muscles, the erector spinae and hip flexors.  In practice, it’s a little more complicated.

I continued to do roughly the same workout routine I’ve done for years, but I modified it to focus on those goals.  I added planks and hip abductor exercises to my weight training routine.  I added stretches for the erector spinae and hip flexors.  I also started doing pull ups with a reverse grip so as to focus on the deltoids (delts) to try to pull my shoulders back.

I also recently switched to a standing desk, which appears to be a trend among developers these days.  I definitely like my standing desk, but I don’t believe it is a solution in itself.  In fact, a standing desk can actually cause injury for individuals that have been sitting for years if the switch is abrupt.  Standing tends to put more stress on the lower back if you previously had problems with weak abs or glutes.  When I first switched, I definitely felt pain in my back, so I dialed it back and gave my body time to adjust.

It’s been almost a year since I decided to focus explicitly on posture.  My posture has improved dramatically, though it still isn’t quite where I’d like it to be.  In other areas, however, I’ve noticed very clear benefits.  Since my shoulders are farther back, I’ve noticed that I have much greater mobility on exercises like the bench press.  It’s easier for me to lift things off of the ground and my butt actually has some curvature to it, which I’m told might help with the ladies, though I can’t provide any scientific data to support that assertion.  A problem I had previously with shoulder impingement is essentially gone.  I can stand for longer periods of time without feeling fatigue.  So, in short, I am making progress.

Posture is probably something I will struggle with for the foreseeable future.  However, I have found ways to improve my posture gradually.  The bottom line is that our profession is inherently unnatural in that it requires a great deal of time to be spent in a stationary position.  To the extent that we can break up that pattern by taking breaks, stretching, working out and remaining mobile, we can be better, healthier, longer-living. more productive and sane developers.

Huge survey reveals seven social classes in UK

Wealth Inequality in America

Wealth Inequality in America, The Critique

There are more discussions on Youtube about this video.


Huge survey reveals seven social classes in UK

3 April 2013 BBC

John Cleese, Ronnie Barker and Ronnie Corbett in the Class Sketch

People in the UK now fit into seven social classes, a major survey conducted by the BBC suggests.

It says the traditional categories of working, middle and upper class are outdated, fitting 39% of people.

It found a new model of seven social classes ranging from the elite at the top to a “precariat” – the poor, precarious proletariat – at the bottom.

More than 161,000 people took part in the Great British Class Survey, the largest study of class in the UK.

Class has traditionally been defined by occupation, wealth and education. But this research argues that this is too simplistic, suggesting that class has three dimensions – economic, social and cultural.

The BBC Lab UK study measured economic capital – income, savings, house value – and social capital – the number and status of people someone knows.

The study also measured cultural capital, defined as the extent and nature of cultural interests and activities.

The new classes are defined as:

Audio here (Check source)

  • Elite – the most privileged group in the UK, distinct from the other six classes through its wealth. This group has the highest levels of all three capitals
  • Established middle class – the second wealthiest, scoring highly on all three capitals. The largest and most gregarious group, scoring second highest for cultural capital
  • Technical middle class – a small, distinctive new class group which is prosperous but scores low for social and cultural capital. Distinguished by its social isolation and cultural apathy
  • New affluent workers – a young class group which is socially and culturally active, with middling levels of economic capital
  • Traditional working class – scores low on all forms of capital, but is not completely deprived. Its members have reasonably high house values, explained by this group having the oldest average age at 66
  • Emergent service workers – a new, young, urban group which is relatively poor but has high social and cultural capital
  • Precariat, or precarious proletariat – the poorest, most deprived class, scoring low for social and cultural capital

The researchers said while the elite group had been identified before, this is the first time it had been placed within a wider analysis of the class structure, as it was normally put together with professionals and managers.

At the opposite extreme they said the precariat, the poorest and most deprived grouping, made up 15% of the population.

The sociologists said these two groups at the extremes of the class system had been missed in conventional approaches to class analysis, which have focused on the middle and working classes.

Methodology

Professor of sociology at Manchester University, Fiona Devine, said the survey really gave a sense of class in 21st Century Britain.

The survey has really allowed us to drill down and get a much more complete picture of class in modern Britain”

— Prof Fiona Devine, Manchester University

“What it allows us is to understand is a more sophisticated, nuanced picture of what class is like now.

“It shows us there is still a top and a bottom, at the top we still have an elite of very wealthy people and at the bottom the poor, with very little social and cultural engagement,” she said.

“It’s what’s in the middle which is really interesting and exciting, there’s a much more fuzzy area between the traditional working class and traditional middle class.

“There’s the emergent workers and the new affluent workers who are different groups of people who won’t necessarily see themselves as working or middle class.

“The survey has really allowed us to drill down and get a much more complete picture of class in modern Britain.”

Video here (Check source)

The researchers also found the established middle class made up 25% of the population and was the largest of all the class groups, with the traditional working class now only making up 14% of the population.

They say the new affluent workers and emergent service workers appear to be the children of the “traditional working class,” which they say has been fragmented by de-industrialisation, mass unemployment, immigration and the restructuring of urban space.

What class are you?

Class figures

  • The full class survey takes about 25 minutes and covers wealth and job type, interests and social circle
  • Compare your score to the nation’s
  • Receive a personalised coat-of-arms

BBC Lab UK worked with Prof Mike Savage of the London School of Economics and Prof Devine on the study.

The findings have been published in the Sociology Journal and presented at a conference of the British Sociological Association on Wednesday.

Researchers asked a series of questions about income, house value, savings, cultural and leisure activities and the occupations of friends.

They were able to determine a person’s economic, social and cultural capital scores from the answers and analysed the scores to create its class system.

The GBCS was launched online in January 2011, but data showed participants were predominantly drawn from the well-educated social groups.

To overcome this a second identical survey was run with a survey company GFK, with a sample of people representing the population of the UK as a whole, using the information in parallel.

Akin’s Laws of Spacecraft Design

Nice engineering tips.

译文:航天飞机设计定律


Akin’s Laws of Spacecraft Design

Date here Author here

1. Engineering is done with numbers. Analysis without numbers is only an opinion.

2. To design a spacecraft right takes an infinite amount of effort. This is why it’s a good idea to design them to operate when some things are wrong .

3. Design is an iterative process. The necessary number of iterations is one more than the number you have currently done. This is true at any point in time.

4. Your best design efforts will inevitably wind up being useless in the final design. Learn to live with the disappointment.

5. (Miller’s Law) Three points determine a curve.

6. (Mar’s Law) Everything is linear if plotted log-log with a fat magic marker.

7. At the start of any design effort, the person who most wants to be team leader is least likely to be capable of it.

8. In nature, the optimum is almost always in the middle somewhere. Distrust assertions that the optimum is at an extreme point.

9. Not having all the information you need is never a satisfactory excuse for not starting the analysis.

10. When in doubt, estimate. In an emergency, guess. But be sure to go back and clean up the mess when the real numbers come along.

11. Sometimes, the fastest way to get to the end is to throw everything out and start over.

12. There is never a single right solution. There are always multiple wrong ones, though.

13. Design is based on requirements. There’s no justification for designing something one bit “better” than the requirements dictate.

14. (Edison’s Law) “Better” is the enemy of “good”.

15. (Shea’s Law) The ability to improve a design occurs primarily at the interfaces. This is also the prime location for screwing it up.

16. The previous people who did a similar analysis did not have a direct pipeline to the wisdom of the ages. There is therefore no reason to believe their analysis over yours. There is especially no reason to present their analysis as yours.

17. The fact that an analysis appears in print has no relationship to the likelihood of its being correct.

18. Past experience is excellent for providing a reality check. Too much reality can doom an otherwise worthwhile design, though.

19. The odds are greatly against you being immensely smarter than everyone else in the field. If your analysis says your terminal velocity is twice the speed of light, you may have invented warp drive, but the chances are a lot better that you’ve screwed up.

20. A bad design with a good presentation is doomed eventually. A good design with a bad presentation is doomed immediately.

21. (Larrabee’s Law) Half of everything you hear in a classroom is crap. Education is figuring out which half is which.

22. When in doubt, document. (Documentation requirements will reach a maximum shortly after the termination of a program.)

23. The schedule you develop will seem like a complete work of fiction up until the time your customer fires you for not meeting it.

24. It’s called a “Work Breakdown Structure” because the Work remaining will grow until you have a Breakdown, unless you enforce some Structure on it.

25. (Bowden’s Law) Following a testing failure, it’s always possible to refine the analysis to show that you really had negative margins all along.

26. (Montemerlo’s Law) Don’t do nuthin’ dumb.

27. (Varsi’s Law) Schedules only move in one direction.

28. (Ranger’s Law) There ain’t no such thing as a free launch.

29. (von Tiesenhausen’s Law of Program Management) To get an accurate estimate of final program requirements, multiply the initial time estimates by pi, and slide the decimal point on the cost estimates one place to the right.

30. (von Tiesenhausen’s Law of Engineering Design) If you want to have a maximum effect on the design of a new engineering system, learn to draw. Engineers always wind up designing the vehicle to look like the initial artist’s concept.

31. (Mo’s Law of Evolutionary Development) You can’t get to the moon by climbing successively taller trees.

32. (Atkin’s Law of Demonstrations) When the hardware is working perfectly, the really important visitors don’t show up.

33. (Patton’s Law of Program Planning) A good plan violently executed now is better than a perfect plan next week.

34. (Roosevelt’s Law of Task Planning) Do what you can, where you are, with what you have.

35. (de Saint-Exupery’s Law of Design) A designer knows that he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away.

36. Any run-of-the-mill engineer can design something which is elegant. A good engineer designs systems to be efficient. A great engineer designs them to be effective.

37. (Henshaw’s Law) One key to success in a mission is establishing clear lines of blame.

38. Capabilities drive requirements, regardless of what the systems engineering textbooks say.

39. The three keys to keeping a new manned space program affordable and on schedule:
       1)  No new launch vehicles.
       2)  No new launch vehicles.
       3)  Whatever you do, don’t decide to develop any new launch vehicles.

40. Space is a completely unforgiving environment. If you screw up the engineering, somebody dies (and there’s no partial credit because most of the analysis was right…)


*I’ve been involved in spacecraft and space systems design and development for my entire career, including teaching the senior-level capstone spacecraft design course, for ten years at MIT and now at the University of Maryland for more than a decade. These are some bits of wisdom that I have gleaned during that time, some by picking up on the experience of others, but mostly by screwing up myself. I originally wrote these up and handed them out to my senior design class, as a strong hint on how best to survive my design experience. Months later, I get a phone call from a friend in California complimenting me on the Laws, which he saw on a “joke-of-the-day” listserve. Since then, I’m aware of half a dozen sites around the world that present various editions of the Laws, and even one site which has converted them to the Laws of Certified Public Accounting. (Don’t ask…) Anyone is welcome to link to these, use them, post them, send me suggestions of additional laws, but I do maintain that this is the canonical set of Akin’s Laws…