Saturday, March 15, 2014

Let's insert some sanity into prison policy

The Onion nails a serious issue with spectacular satire.

15 Years In Environment Of Constant Fear Somehow Fails To Rehabilitate Prisoner

How terrible are our prisons?  The Justice Department studied the issue and estimated that in 2008 there were 216,000 rape victims in US prisons suggesting that more than half of all rape victims are men.  Notice that it is a count of rape victims such that repeated rapes of the same victim is counted once.  The bi-partisan Commission on Safety and Abuse in America's Prisons describes the high level of overcrowding and violence in their 2006 report.   

Of course, there are some terrible people in prison that warrant severe punishment.  However sixty percent of the inmate population are there for nonviolent offenses; one-fourth of the inmate population are there for nonviolent drug offenses.  Ignoring whether sending nonviolent criminals into this environment is moral, the natural response is that severe punishment is a deterrent to crime.   However, the literature overwhelmingly supports certainty of punishment as a far more effective deterrent than severity of punishment.

During this time of budget austerity pressures, people are finally noticing that incarcerating inmates is expensive.  In a state like California it annually costs $47,000 per inmate.  The average across states is a little more than $32,000.  Note that these are accounting costs that fail to capture lost work opportunities and time away from parenting and loved ones.

Naturally, we should support the Attorney General as he recommends lowering sentences for nonviolent drug offenders.  More broadly, we should consider whether it makes sense for us to pursue the expensive yet less effective strategy of incarcerating nonviolent inmates in inhumane environments for lengthy periods of time.  

Tuesday, March 4, 2014

The speed of a vehicle and pedestrian mortality

The over four thousand pedestrians killed ever year from motor vehicle collisions have motivated the following graphic.

From PEDS

Naturally, we expect the likelihood of mortality to increase as the vehicle travels faster and physics suggests that it will be nonlinear.   But like anything else, we want to make decisions based on accurate information and understanding of risk.

These estimates originate from research using 1980s and earlier data more likely to report serious injuries.  From the abstract of a literature review published in 2011.
Without exceptions, papers written before 2000 were based on direct analyses of data that had a large bias towards severe and fatal injuries. The consequence was to overestimate the fatality risks. We also found more recent research based on less biased data or adjusted for bias. While still showing a steep increase of risk with impact speed, these later papers provided substantially lower risk estimates than had been previously reported.
These authors produced the following table in their 2009 paper containing the following table.

Rosen and Sander (2009)
Clearly, estimates that correct for the bias or use less biased data are much lower than those suggested by the popular graphic.  Mind you, it's still the case that the likelihood of mortality rapidly increases as vehicle speed increases and that serious injuries are important too.

From DOT HS 809 021 October 1999
Note: Given the 2011 literature review, the table is potentially biased given that the paper is written so close to the year-2000-threshold.  The mortality estimates roughly match later estimates, however, suggesting that the table is based on less biased data.   
Broadly speaking, as a person who advocates transportation networks with strong walking and bicycling options, relying on bad or biased estimates when better options are readily available to make our points is a terrible strategy.  Besides being ethically questionable, it (1) makes advocates look naive, (2) sets expectations too high, and (3) leads to poor decision-making.  For example, suppose we believe the graphic such that a pedestrian struck by a vehicle traveling at 40 mph is almost certainly going to die.  One might reasonably conclude that there is no point in traffic calming a 50 mph arterial since there is nothing to be gained until you get below 40 mph.  However,  that's not the case based on the more robust estimates.

EDIT:

We can see the bias in this graph by Rosen.  You can see how the risk curves are dramatically shifted left when using the biased data.

Sunday, December 22, 2013

Warped brake clamp marring my handlebar

Swapping a handlebar and stem on an old bike created a small problem with a bent brake clamp.  The bike is outfitted with the original Dura Ace component group.  Unlike a modern brake lever clamp, a screw connected to the clamp is tightened with a nut directed away from the handlebar.

Screw threads go through red hole in brake lever.
Notice that the clamp is stretched towards the threads.

Nut tightens the screw on the far side of red hole. 
The unfortunate effect of the clamp warping is that installing the brake lever mars the handlebars.  The clamp tears even a thin protective surface like painters tape.  Soon it becomes impossible to turn the clamp any further.

An attempt to protect the handlebar with some painters tape.

Just a small turn demonstrates the relative
size of the clamp to the 23.8 mm handlebar.  

The marring from an earlier attempt.
At the moment, I think that there are three options:

  1. Just insert the clamp as is scratching the handlebar along the way.  Afterward, it will be wrapped in handlebar tape thereby hiding the scratches.
  2. Use another set of brake levers.  However, I'd strongly prefer keeping the entire group together.
  3. Find replacement brake clamps.
Option #3 is the most attractive option but finding an effective clamp for a 35-year-old brake lever might be a little tricky.  I happen to have a modern set of Shimano STI levers and Shimano 600 brake levers at the moment.  The brake clamp from the STI levers are clearly too wide.  The Shimano 600 clamp looks like a decent fit although the beveling for the clamp on the inside of the two levers are noticeably different.  I imagine that mating the two would warp the Shimano 600 clamp and I'd like to avoid damaging the original clamp.

Loose Screws and Nuts -- at least until they sell all of their stock and close -- has some replacement Shimano and Dia Compe clamps.  Anyone know a good fit for the classic Shimano brake lever?  Alternatively, is there another strategy for using the old clamps that avoids marring the handlebars?    

Tuesday, November 12, 2013

Why I stopped watching football

Despite a long love of watching and playing football, I stopped watching the game as evidence of brain injuries associated with playing the game mounted.   In addition to the moral issue of watching a game where economically disadvantaged youth make gambles to "make it big", I wondered whether my son might ever want to play and my future response.

Despite a heightened awareness of brain injuries in the sport, I plan on strongly advising against playing the organized game.  In addition to the concussion problem the press popularized for more than 10 years, its becoming clear that we have a poor understanding of what leads to brain injury and that repeated hits to the head appear to cause changes in the brain without any clinical evidence of a concussion.

To quickly summarize the statement above and the presentation in this video, high school football players had their helmets wired to measure blows to the head.  Over two seasons, players were monitored during games by researchers at Purdue and periodically performed cognitive tests while undergoing MRIs.  Players that suffered clinical concussions as well as those that registered many helmet hits without a clinical concussion, described as subconcussive hits, had similar brain changes during the season.

In other words, those with lots hits without a concussion had brains like those we know had (minor) brain damage.

In the end, it seemed somewhat hypocritical to watch and enjoy a game but (potentially) tell my son that I had serious qualms about him playing the sport.  If he makes a compelling argument, I might still say yes; I think one needs to let them lead their own lives with some guidance.   However, no longer watching might give my argument greater credence and be more persuasive.  That possibility is worth more than watching the game.

Thursday, October 3, 2013

What does this screw do?

The Dura Ace seat post is a late 80s/early 90s model.  My guess based on the other components; it came with a touring that had a seven speed MTB 135 OLD rear hub.  My question is straightforward: What does that screw do?  


I image that it would affect or limit the tilt of the saddle.  But asking before I unscrew/loosen it seemed like a far better idea.

Thursday, September 26, 2013

Why I always back into driveways

Several consumer and safety groups are pushing for rear-view cameras to prevent back-over crashes.  While it's a worthwhile cause, I back into driveways to avoid these and other types of terrible accidents.

As a person approaches a driveway, he/she will almost always have an excellent view of the sidewalk and driveway.  Perhaps just as important, pedestrians and children in the area expect cars to be in the street and typically have an unimpeded view of the road with respect to seeing an automobile.  In addition to engine noise, moving from the street to sidewalk/driveway usually creates more noise further alerting any people in the area that an automobile is approaching.  In short, when parking the driver has an excellent view of the area to observe a child or other hazard and pedestrians have an easy time recognizing that an automobile is approaching.

When a person exits the driveway, he/she has an excellent view of everything in front.  Certainly a child that isn't underneath the car will be seen in normal circumstances.  The driver will have a better chance of seeing and reacting to pedestrians hidden by hedges, trees, and other objects.

Writing broadly, I (almost) always back into spaces in parking lots for many of the same reasons above.  With a little practice it gets much easier.  Everyone should do it.

Sunday, July 7, 2013

How "gluten-free" does a gluten-sensitive person need to be and is it important to purchase products explicitly gluten-free?

Over the past decade, there has been a growing literature that recognizes a set of disorders associated with gluten intolerance in addition to celiac disease.  There is little to do for the roughly 1- and 10-percent of the population thought to have celiac disease or gluten intolerance other than eliminate gluten from their diet.  However, following a gluten free diet poses it's challenges since gluten is either a direct component -- often from wheat -- or enters as a contaminent.  In fact, even "gluten-free" products actually contain small amounts of gluten.  This raises two questions: One, how much gluten can a gluten sensitive individual tolerate and, two, how contaminated are traditionally gluten free products?

Research on the gluten limits are understandably directed at celiacs since it has long been recognized as a disorder and there are observable symptoms.  The studies generally take the form of giving people regular doses of gluten and then evaluating their response to them.  Consider the two literature summaries by the FDA and Akobeng and Thomas.  Even a casual reader will immediately recognize two broad results.  One, within each study the scientists recognize a wide range of individual tolerance.  Two, the recommended thresholds across studies also have a wide range in part dues to whatever metric(s) they find important, the duration of the experiment, and what percentage of celiacs the recommendation is targeting. With just a small sample of studies, I've seen recommendations for less than 1 mg10 mg, and 50 mg of gluten a day.  Broadly speaking, the recommended threshold I've seen most often 10 mg/d.  It's pretty clear that this should be considered a starting point for gluten sensitive individuals.    
The gluten microchallenge disclosed large interpatient variability in the sensitivity to gluten traces. Some CD patients showed a clear-cut worsening of the small-intestinal architecture after ingesting only 10 mg gluten/d, whereas others had an apparent improvement in mucosal histology after the 3-mo challenge with 50 mg gluten/d. Furthermore, one patient challenged with 10 mg gluten/d experienced clinical symptoms after a few weeks, whereas none of the 13 subjects receiving 50 mg gluten/d had clinical evidence of relapse. (reference)
In case it is unclear, 10 mg/d is a teeny tiny amount of gluten.  A typical diet is estimated to contain 10 to 40 grams of gluten.  Taking the lower bound of 10 grams, a person would be limited to one-thousandth of that amount.  A single slice of wheat bread contains orders of magnitude more gluten!

Pursuing a gluten-free diet requires dedication and moderate effort.  It quickly becomes apparent that products explicitly labeled gluten free are often quite expensive even though they are theoretically gluten free.  How worried should one be about possible wheat/gluten contamination of say something like oats which should naturally be gluten-free?  There are studies that randomly sampled and test commercial products for gluten and concluded that one should indeed be worried if one is targeting some commonly accepted thresholds -- 20 parts-per-million is what one generally sees in the US -- for a product to be gluten free.
Thompson, 2004
A broader study that included the same author concluded ...
Twenty-two inherently gluten-free grains, seeds, and flours not labeled gluten-free were purchased in June 2009 and sent unopened to a company who specializes in gluten analysis. All samples were homogenized and tested in duplicate using the Ridascreen Gliadin sandwich R5 enzyme-linked immunosorbent assay with cocktail extraction. Thirteen of 22 (59%) samples contained less than the limit of quantification of 5 parts per million (ppm) for gluten. Nine of 22 (41%) samples contained more than the limit of quantification, with mean gluten levels ranging from 8.5 to 2,925.0 ppm. Seven of 22 samples (32%) contained mean gluten levels >/=20 ppm and would not be considered gluten-free under the proposed FDA rule for gluten-free labeling.
Consequently, if one is maintaining a gluten-free diet one must use uncertified products with some caution.  Although as a quick aside, it does matter how much of the product one consumes.  The 20 ppm recommendation is based on an assumption of how much gluten-free flour one is consuming -- the rough assumption is half a kilogram -- and the aforementioned 10 mg daily limit.  If one is less sensitive or eats less than those assumptions, than one might be willing to take greater risks.

An obvious assumption here is that studies on celiac disease are applicable to other forms of gluten sensitivity.  Since other gluten disorders have only recently become broadly recognized the literature is very sparse and the assumption is unavoidable, in my opinion.  The important point is that if one is trying a gluten-free diet in response to some symptoms, one should be proactive with one's diet and pay close attention to its effects.  Naturally, this brings up a discussion about placebo effects ...