Wednesday, October 29, 2014

2-wheeled vehicle accidents--Forensic Engineering

I am currently doing a 4-week rotation in the OCME--Office of the Chief Medical Examiner. I'm learning so many cool things. However, for my many triathlete and road biking friends, I wanted to put a little post about what I have learned about motorcycle accidents from the Forensic Engineering book I am reading.

Per-mile, motorcycles have ~2.6x more accidents than cars. However, as many more people drive cars, motorcycles only account for 1.3% of all MVAs. However, motorcycle accidents cause at least 10% of all motor vehicle deaths and motorcycles have ~ 20x more fatalities per mile driven than cars.
The greater fatalities can be explained by the fact that there is nothing but the impact of body against the ground to dissipate all of the kinetic energy from the crash (remember kinetic energy = 1/2mv^2, with m - mass & v = velocity).

 The greater number of accidents, however, is not as well explained. It can be argued that there should be fewer accidents as "fewer infirm and feeble persons drive motorcycles than cars" hence "the average motorcyclist should have better reflexes and therefore react faster in accident situations" 

One example of a common accident is when a car is making a left turn into a driveway or a cross street and hits a motorcyclist heading straight. A major factor within these accidents seems to be the perception of the motorcyclist by the driver-who doesn't see the motorcyclist or only sees the motorcyclist when it is too late.

Perception of headlights. People can use the rate of change of angle between the two headlights to estimate the distance of the car and the speed of the car. Further there is a linear correlation between the rate of change of headlights, so it is fairly easy to estimate distance & speed.


On a motorcycle with one headlight at night, only light intensity (how bright the light is to your eye) and change in light intensity can be used to estimate change in speed.

This is very difficult for MANY reasons
                * The brightness of headlights varies greatly
                * The aim of the headlight affects the brightness perceived by drivers
                * The slope of the road affects perceived brightness
And the most impressive:
                * To estimate velocity, a driver must estimate by watching the change in intensity of a light.

Change in intensity has an exponential relationship to distance, not a linear relationship that holds for watching the angle between two headlights.



 
This means that to have adequate light intensity to judge distance, the motorcyclist is probably already too close to the driver to prevent an accident.

The next major point is Daylight Perception

The width of a 1975 ford mustang is 72 inches. A person with 20/20 vision can read 4-point font @12in and can recognize a 72-in wide car when the car is 1,375 feet away, which is ~1/4 mile. 

The width of a motorcycle is ~20 inches. A person w/ 20/20 vision can recognize the motorcycle when it is only 573 feet away.

It is legal to drive with 20/50 vision which means that the driver will recognize a 72-in wide car at 550 feet away and a motorcycle at 229 feet away.

A driver with 20/50 starting from a stop and making a left hand turn will have adequate time to react to a car at 550 ft away as long as it is moving less or equal to 147ft/s or 100mph. However the same driver with 20/50 vision starting from a stop and making a left hand turn will have adequate time to react to a 30-in wide motorcycle at 229 feet away if the motorcycle were moving less than 61ft/s (42mph).

Typical hard braking deceleration for a motorcycle was 16ft/s/s, meaning a motorcycle needs 2.76 seconds to come to a complete stop from an initial speed of 42mph, greatly limiting the amount of time to make an evasive move from a car.

Now a more contentious point supported by engineering is that motorcycles stop more slowly than cars. This makes sense insofar as the WEIGHT of a vehicle is NOT important when calculating the conversion of kinetic energy from velocity into the energy dissipated by friction
KE = 1/2 mv^2 = weight/2g*v^2 with g being the force of gravity
Energy dissipated by friction = weight(w) x distance(d) x coefficient of friction(f)
therefore v^2 = 2g*d*f with the weight cancelling out

However, maybe braking systems, etc have developed since this book and other forensic engineering books were published.

The author of my new book leaves us with the thought that maybe as the width of a car is 2.5x greater than a motorcycle, this explains that there are 2.6 times greater motorcycle accidents than cars.

I hope that my biker friends (including cyclists) can use this knowledge to keep themselves safe from accidents! 

Remember, it is difficult to impossible to judge distance and speed from a headlight. It is much more difficult to see a narrow biker than to see a wide car.

Best wishes! For more Forensic Engineering fun check out this book, my main reference for all of the above. I HIGHLY HIGHLY recommend it!!



http://www.amazon.com/Introduction-Forensic-Engineering-Library/dp/0849381029/ref=sr_1_8?ie=UTF8&qid=1414624012&sr=8-8&keywords=forensic+engineering

Thursday, April 18, 2013

Reflection on this week Boston, Steve Arch, and an injury

This school year has been a crazy learning time and personal development time for me. Currently I am recovering from a stress fracture... that I got when I could barely run again after months of injury! What happened is I tried to do my first long run on trails and ended up turning my ankle a few times, avulsing the fibula, a non-weight bearing bone. This means that I can barely walk down stairs without shooting pain. So I effectively have gotten to run less than 10 days since September and my knee injury when running was my #1 stress-reliever, etc, etc. I may be able to run in two more weeks, which will make it six weeks since I last tried to run and eight weeks since the fibular injury.

This weeks news has brought me to an emotional location. The boston bombing is astounding. That could have been myself and my family. It was well after the elites, so in reality it will be professional Courtney 10 years from now once I have fallen out of shape during residency and getting back into shape with my family finally able to cheer me on... as I have a good amount of family in that area. And maybe some little ones also cheering me on (as having future kids may help me be out of shape due to juggling residency/new jobs/motherhood). We are treating it as a terrorist attack because actions such as that are unacceptable and we are going to ensure safe living circumstances for our own citizens. We try to establish it for the world, but we cannot determine the fate of other countries. Then the horrible destruction in Texas. So much destruction.

The most reflective moment comes with the death of my former advisor and in many ways hero Steve Arch. He was a big, lumbering man with destroyed knees who reliably sat in his office many days of the week with a dragonfly lamp lit. He played basketball at noon every tuesday thursday and was renowned for throwing elbows. He taught me so much in our conversations. I was scared to talk science with him as he was a neuroscience genius and could make anyone feel completely stupid if he wanted. He set up seminars that were from 8-10 at night where all the students sat around, drank a beer, and talked about the latest research. That is the life. Waking up your mind as you relax the body, where learning knows no limits.

But what he taught me went so beyond the classroom. I remember one time sitting down with him and him asking me, seemingly out of nowhere "if you're going out with a group of friends to eat, where would you go?" and I thought about all the exotic food I would love to try and started to respond maybe the moroccan restaurant with belly dancers, or a thai restaurant, or... and he cut me off "No, you're going out with friends. It doesn't matter where you eat, what matters is the company." Another time I was upset about friends trying different drugs that I considered completely unacceptable (heroin, etc) and discussed that with him and during our discussion he agreed with me but also reminded me how to be more open-minded. That people's curiosity is what drives us into science and to make the greatest discoveries of all time. What we don't want to do is condemn curiosity or the vision or exploratory nature. A wonderfully contrasted point of view to the narrow one I presented (not that he condoned the use of heroin).

In many ways he embodies for me what it means to be a real man, what it means to be strong in our convictions. In those talks he taught me so much. So much about passion and perspective. The need to explore, be curious, to question and undermine our everyday assumptions, whether they be about health, science, biology, physics, people, etc, etc. I ran my first marathon while his advisee and he was proud, but recommended against doing a second because it takes so much time that could be invested in something else (I also took carpinetry lessons, joined both a flamenco and hip-hop dance troupe, and most importantly spent many many many hours in the laboratory doing mediocre work.... as science takes training and focus and i had inadequate training for good work at that point).  Only after his death did I find out that he had been offered a slot to play professional football with the chicago bears that he turned down to attend graduate school. Because waking up the mind and exploring the world was in his eyes the essence of life, as was his family and love. Sports was just a small part of it all.

As I go forward I will try to remember all those things he did teach me about being strong: forceful yet kind, intimidating yet caring. He wrote poetry that he only let me see once... after I showed him some poetry about DNA replication experiments that I had written. His poetry was not meant to be shared. It was meant to help him appreciate the details and intricacies of the world around us. I am so sure that if more people got to have an adviser like Steve Arch in their lives that the world would be a much better, interesting, and functional place. I know that if I had kept in better touch with him I probably would have made much better decisions about my daily life and choices and time devotion. He told me that to become what I want to become I need to be reliable and predictable. This is one of the hardest traits for me to develop... what something shiny? Yes I do want to go look at it... oh I had an appointment? Yet being predictable is one of the key traits of being a doctor or a teacher. People need to depend on me to take their call and be in my office.

This has been a week of tears and studying and not running. Usually I would process the meaning of all this while running. But I cannot. So I will clean my house, push my vacuum, do some lunges, and think about how fortunate I am to have the people I have. And how I can change the world so that people do not die in needless explosions. Whether it be due to a fertilizer plant or another human being. We need to be strong, curious, and explore to find better answers than the ones we have.

Thursday, March 21, 2013

Where to call home


On my way to the river on Tuesday this song was playing and I sang it to myself as I went into and out of the wave, playing... I realize this song is about men and women, but for me it is about going home. When I left Montana I gave up the place I love and I had decided to call home. I left the first place I have ever truly been able to call home, where I came to fit in, despite being hyperactive and just wanting to play in the mountains, to come to dc.



The hardest decision was to not go back after my mom died. I had always dreamed of being a doctor and with my mom I found that I was truly talented. I had applied soon after coming home and gotten accepted first try. There are no medical schools in Montana, but there are in Virginia and I was just a couple of months from officialy becoming a Montana state resident. So I could still get Va in-state tuition. The timing was perfect. But I still had the option of returning to my program where I was happy.

When I made the decision to leave everyone told me "the mountains will always be here, but your mom won't be." But then after I had been here for a few months and went back to visit my coworkers started to encourage me to go back. "your face just lights up whenever you talk about it." Apparently the only time I really shone was when I talked about going home.

I took my first kayaking lesson the first weekend I was in DC. Kayaking was my consolation prize for giving up my home to care for my dying mother. One day while waiting outside Duke's cancer institute in a meditation garden before going in to meet with a doctor about her case I made a promise. That while she was alive I would do everything to save her. And when she died I would do everything in my power to help others in her honor. But did this really mean that I still couldn't go home? When will it be time to go back home?


Now this spring break vacation my dad had surgery. It is his seventh on his left eye to attempt to recover his vision as he has hereditary glaucoma. It seems that the pressure is up in his right eye and he may need to operate on that soon, his only seeing eye, or else both eyes may go.





I would have loved to go home to Montana and gone skiing and seen my friends and have been in the mountains. But I made my decision to be here and put my family first. Only two and a half more years and then I will hopefully be able to move closer to where I feel most at home. It is crazy how different my life is based on that one decision. All the people I have met and all the things I have done. I would never have won a running race or even known I could be pretty good at running. I wouldn't know how to roll a kayak, much less have worked on flipping it around. I would not be in medical school and never known that I have "world class empathy" and can be "a great doctor" as I was told recently following an exam in my practical application class. And most importantly, I wouldn't have gotten this time with my family. And so I listen to my songs as I play around in the waves for a few hours and reassure myself that the mountains and rivers will still be there when I get back.









Thursday, March 7, 2013

Removing the tube

Yesterday in class we had a lecture about Advanced Life Directives. This brought up a lot of painful memories for me that have made me cry a lot in the last 24 hours. I wrote the dean a letter that I copied below. I have not re-read it because it would be too difficult, so I am sorry for the spelling errors, etc. Today I went for a run and smiled the whole time. This is a good thing to process, but very difficult and will take a long time.

Hi Dr. Babineau,

Yesterday's lecture brought up a lot of issues for me and another student suggested I briefly talk to you about it. I took responsibility for my mom's life and she took chemo for me. In the process of me giving up my previous graduate education and moving back home to be with her I guess I proved myself the most medically capable in my family and the one people would trust with big decisions. I should back up. Before I was born my mom had a dog, Zorba, who was a little terrier or poodle, or something small. It hated my dad because my mom belonged to Zorba. When my mom had to put Zorba to sleep she saw that my dad couldn't handle the decision. So she had advanced directives put into writing that said if after two days on life support she had no hope of recovering to her previous functioning level (i.e. she didn't want to live with depleted mental abilities) she wanted the breathing tube removed. She put her sisters in charge of her breathing tube because she saw how difficult and painful that decision was for my dad, even if it was the right thing to do.

My entire life my mom made us firmly aware of these advanced directives. Especially aware after my sister's friend in middle school was hit by a car, flew 15 feet in the air, landed on her head, and was in a coma for over a year and came back going from the school's valedictorian to being mentally retarded. My mom and I visited her a lot (she learned my name and asked for me when I didn't know her before the accident and yet couldn't remember my sister's name). Caring for Lily after the accident, visiting her in the hospital then at home, was an important experience in my life and in my and my mom's relationship. One that no one else knows about, though I spent much time doing it.

Anyways, when my mom had her final seizure from her brain tumor and was intubated and brought to the hospital, she had already lost most of her capabilities, she couldn't feed herself, she couldn't name the months backwards, she was living her worst nightmare. I had asked her previously if she wanted me to be responsible for saying no to the tube and she had said yes as adamantly as she could despite being unable to say much more. It was horrible that day coming home from the hospital, she was only able to open her eyes, being paralyzed all over other than that, and seeing her blood on the floor with syringe wrappers, and slowly cleaning it up by myself. My heart completely breaking. At the hospital I had grabbed her hand and she had rubbed it with my thumb very soon after the ambulance arrived. That was the last time she ever moved her hand, showing me that she knew I loved her and I was there for her.

My family fell apart very predictably. Everyone was malfunctional. Her sisters came down and were just overwhelmed with the tragedy. My dad was extremely lost as he had been for so long. My sister and I began to have an extremely antagonistic relationship and she ended up punching me in the face when I asked her to leave as she was talking loudly on the phone while I was reading to my mother, making me bleed. My mom's eyes had kept roaming, looking for where the other voice was coming from whenever my sister started talking. For some reason, this was extremely distressing to me that I couldn't just read to my mother. I know how irrational and crazy family can get. When we have to change our lives to watch someone we love so deeply die it makes us unpredictable and antagonistic and defensive and strange.

So no longer rambling, when it came down to it my mother's sisters didn't do their job to remove my mom's tube and kept saying that it was my dad's responsibility. My dad told me he thought my mom was glaring at him every time she looked at him, incriminating him. So I went to find the advance directives to bring them to the hospital and take the responsibility off of everyone's shoulders and put the burden of making the decision to honor my mother's wishes by killing her onto my own shoulders. I know that it is letting her die, but there is something about saying I am removing her life line that feels akin to shooting a horse, it feels like a merciful killing. And I was willing to do the killing because as I took responsibility for her life, I was willing to take responsibility for her death. I left the advance directive out overnight so that people could be aware of my intentions and my family went crazy on me.

I didn't bring it in because they would have never forgiven me. Two weeks later my sister, my dad, and I all sat together as I watched the palliative care doctor persuade my dad it was time to remove the tube. My dad looked sick and his eyes bulged out of his head. He was making the decision that was the most painful and horrible decision to make and was not his to make. Unfortunately by the time we removed the tube my mom was out of status epilepticus and stabilized and lived for another month in a paralyzed-semi-comatose state. For another month she could have died at any second. We were all complete wrecks and spent most of our time with her in hospice. It was hell. I believe I made the right decision by not honoring my mother's wishes because I know she loved my father and fought to live to give him strength. Letting him have whatever modest amount of control he could have in the most nightmarish situation imaginable was what my mother would have wanted. But the amount of pain wrapped up into those memories is immense and difficult. I saw a therapist and still speak with her when I need to. But that doesn't change the painful tragedy of that experience. 

One thing that I didn't say that I wanted to tell the class is that when we had that meeting to remove her breathing tube, the palliative care doctor cried with us. She felt the sheer tragedy that was previously unimaginable. She saw my dad's pain as he had to make the decision to let the love of his life die and that he could not save her, that no one could. Those tears were comforting and kept me in the moment, allowing me to acknowledge that this was a horrible situation. Otherwise I would have put up emotional walls and a whole defense system to protect myself. But this was a tragedy so great that it would make even the strongest person with strong walls break down into tears.

Tuesday, February 26, 2013

Breastfeeding I: Colostrum, Antibodies, diarrhea prevention


Human milk provides protection against disease for a baby. There are many ways that it does this, much beyond what I can delineate in my non-studying time allotted. So I will start at the very beginning and then continue later.

A vaginal birth allows the baby's gut to be colonized by healthy bacteria which will deter disease by preventing the growth of unhealthy bacteria. #2 provide essential nutrients such as vitamin K. The proper colonization of the gut is why adults take probiotics, which will be another post.

The first milk secreted by the mother after birth is called colostrum because it is soooo different from 'mature' milk. It actually selectively facilitates the establishment of healthy gut bacteria Lactobacillus bifidus along with aiding the passage of meconium, or baby fecal matter that is still sterile from being in the mother, or not yet full of healthy bacteria.

Colostrum has less kcal than mature milk that will be secreted a few days later but has a higher amount of protein, fat soluble vitamins, and minerals. Further, it has a VERY high level of antibodies against bacteria and viruses that may be present in the birth canal.

These secreted antibodies are called IgA (immunoglobulin A) and are fascinating because the act like little pac-men for the viruses and bacteria. They are secreted by the adult gut and are specific for the topography of bacteria, viruses, etc. The immunoglobuns thus grab onto the bacteria or viruses and hold onto them preventing them from infecting you. In the adult,  IgA is secreted in the nose, the salivary glands, and throughout the gut along with into the breast milk.





In the second trimester of pregnancy, the human breast fills with inflammatory cells and it is thought that it is for this purpose: to identify and greatly increase the amount of secretory IgA made against any bacteria or viruses present in the environment and therefore protect the baby. Not only that but the degree of protection against organisms causing disease is proportional to the amount of HUMAN milk the infant receives, meaning exclusive breast feeding = greater protection vs diseases that cause diarrhea, nausea, etc. It is well established in the medical community that ingested antibodies from human milk provide gastrointestinal immunity against the following digestive tract/enteric pathogens that cause diarrhea: E. Coli, Salmonella typhirium, Shigella, V. Cholerae, Giardia, rotavirus, C. Diff, C jejuni. Therefore the antibodies in human breast milk in combination with the nutrients that help healthy bacteria survive protect the baby against diarrhea, GI ilnesses, etc.

Further the mother secretes immune cells (lymphocytes, T-Cells) that give specific immunity for bacteria present in the environment to the baby whose immune system cannot yet make those bacteria.

Saturday, February 9, 2013

A Brief Update

It is discouraging and scary to be coming back from this injury. Strange that I say this as I have come back from two ACL reconstructions. But there the injury was fixed. This time I know I have no miniscus and a meniscal tear. It is not "fixed" and it is up to me to change my training accordingly. Also running cannot be my priority. My schooling is my priority and that takes up a lot of time and effort. There is no clear path forward.

I went for a 14 mile run on tired legs on Thursday and really died at the end; my legs felt like lead. That used to be easy and at an easy pace (~7:30). Now it is difficult to brutal. My physical therapist said on Friday that people have come back from worse and that I will be back out there. And I will try. I know I am not alone when I run, I know I have my mom and my cat (who I put to sleep when her kidneys failed the day after my mom had been hospitalized with her final seizure. She sometimes visits me in dreams. She had been abused by previous owners, so I spent a lot of time sitting with her until I was the first person with whom she connected.) But is is hard to have loved something so much and have it taken away suddenly, whether it be a mother, a cat, or running. But hopefully I can get it all back.

I know I have strength in me. But between school and being in the worst shape since my ACL reconstructions, it is scary. I'm going to keep plugging away at my schoolwork and keep going to physical therapy and hopefully soon I will be back out there racing with my friends and comrades. I won't be at the front of the pack. That isn't how the body works. I will have to take some time to earn my way back up there. Wish me luck; I need it!

Monday, February 4, 2013

It's okay to be a chubby runner!

It was around 3 o'clock on what was a Tuesday or Wednesday afternoon when I got the call. I was fourteen and was doing nothing much after getting home from school. It was my dad's voice on the phone:

"I've got it Courtney"
"What dad, what have you got?"
"I've got the sport that will take you to the Olympics"
[pause... I'd never thought about going to the Olympics .. didn't have any idea why I was getting this call out of the blue]
"And what sport is that dad?"
"Bobsledding"
[another pause... thoughts of being like the guys in Cool Runnings going through my head]


"Why bobsledding?"
"Because you can run fast and weigh a lot"

[pause as I get kind of excited, sounds like fun, but then I realize....]

"Dad, did you just call me fat?"

Yes that is the call that no fourteen year old girl wants to receive.... the fat call. I was chubby and kinda short. One guy who tried to date me in middle school ACTUALLY tried to flirt with me by calling me Courtney FAT-man before giving me his nike wrist band and trying to hold my hand! But I could still out-sprint most everyone in a soccer game. One time I remember hearing the parents from the other team commenting on how long my legs were... and I am 5'4" now, probably was shorter then, and weighed probably ~140lbs. So I knew didn't have long legs, I could just run faster then their daughters. And I remember telling my dad about that and wondering how fast I had to be running to create the illusion of long legs...

I think that training as a chubby athlete all my life has prevented a lot of injury. It takes a lot more muscle to run in a 140lb body than a 110lb body. Then as I dropped weight while living in Montana, I could sustain those speeds.

Now after having been injured I'm back up to ~127, which is 10-15lbs higher than my ideal racing weight. It will come back off if I keep training. But earlier today I did 5 mile repeats at a sub-6 minute pace (between 5:56 and 5:39) while weighing about 15 lbs more than most girls that can run like that.... As great as it would be to be a bobsledder, I can just stick with running for now and see how far this woman who was a happy-go-lucky Chubby girl can get in the running world :)