This is an experimental blog entry. This is a set of notes, as I keep in my electronic lab book, on building a high-powered IR remote control. This gives you a look into my thought process as I'm starting a project. If you're not a EE or electronics hobbyist, a lot of this probably makes no sense at all. You may want to come back some other time when I'm back to writing prose rather than EE stream-of-consciousness.
This is something I've been thinking about for several weeks, but haven't done anything about. If I make progress on this, I might continue to edit this entry. To that end, I'll note Last Date Edited (and update this if/when I make changes): October 21, 2010.
Optimal wavelength: I've got IR LEDs from 810nm to ?? (lots longer.) What's the peak detection wavelength? The Sharp integrated remote control transceiver modules are at 940nm. Several other IR remotes seem to be at that wavelength as well.
Looking on Digikey for 940nm IR LEDs, there are a bunch. Let's say I want to go with a high-efficiency one, to get peak IR/watt. What are my choices? Searched 940nm in stock, and there are 60. Luminous intensity is given in terms of mW/sr @ xx mA. sr = steradian, but this increases with viewing angle (smaller angle, photons more concentrated). Some choices:
TSAL6100: 80mw/sr @ 100mA, 20 degree angle
TSAL6200: 40mw/sr @ 100mA, 34 degree angle
TSAL5300: 30mw/sr @ 100mA, 44 degree angle
TSAL6400: 25mw/sr @ 100mA, 50 degree angle
TSAL7600: 15mw/sr @ 100mA, 60 degree angle
These are all 5mm (T 1 3/4) LEDs with 1.35V nominal forward voltage. Are these all the same die, with just different optics? (Question: How do LEDs get different viewing angles?) These are Vishay Semiconductor parts.
And what viewing angle do I want for these LEDs anyway? Am I trying to make a remote that has maximum range when aimed, or maximum spread when spraying a large area? Well, if it was a super-TV-B-Gone, I'd go for the widest spread. But the primary goal is maximum range. So I think I'm going ot use the TSAL6100. 20 degree ( +/- 10 degrees of center) for the beam width. MAYBE I'll have one or two wide-beam LEDs just to provide some near-in breadth, at the expense of a little bit of range.
Of course, if narrow and far is really all I want, there's an OSRAM with 160 mW/sr at 10 degree beam width (P/N SFH4545). The forward voltage is 1.5V nominal, and it costs about 10% more than the Vishay parts above...
So how many of them to use? Inverse square law says I need to increase the intensity by a factor of 4 to double the range. So 4 LEDs gets me 2X the range of 1 LED. 16 LEDs gets me 4X the range. 64 LEDs gets me 8X the range. 256=16X, 1024=32X.
What are my limiting factors:
- Size: I can only fit so many LEDs on the front of my device.
- Cost: These things ain't free!
- Power: This is the real limit: at 1.35V Vf I could probably put two in series (2.7V) and still run it with a 3.3V system voltage. But that's nominal... Peak Vf is 1.6V so 3.2V for a stack of two. I could *probably* still get away with running those off a 3.3V rail.
How many of these 2 LED stacks can I run off batteries? I'd like to use 4 AA batteries, switched down to 3.3V for optimal efficiency. Figure 1A peak current is about what I want to draw. 8 x2 stacks of LEDs gets me 800mA. Or do I want to run the LEDs directly off the batteries? Not really, because battery voltage is going to vary from 6.4+V fresh to 4.0V dead, and the current would vary with battery voltage. What about voltage overhead for my switching NPN? Do I want to use a FET instead?
Or instead of doing two LED stacks, do I want to have one per BJT, but with a potentially higher peak current? What's my pulse length? At a slower modulation frequency of 36KHz, we've got a pulse of 1/(2x36000) = 13.8uS. LED Datasheet specifies a peak pulse current of 200mA for 50% duty cycle for pulses less than 100uS, so we're golden. Furthermore, Radiant Power per mA seems to scale pretty well from 100mA to 200mA, so running the LEDs at twice the current is just about the same (in this range) as twice as many LEDs.
Waveform: Remotes vary in the frequency of the carrier: 40KHz, 38KHz, 36.x KHz... I'd like to have the hardware capable of hitting all of these. Ways to generate a modulated carrier:
- Bit bang all the way - This is sloppy & potentially dangerous. If I'm running the LEDs at 2X nominal forward current because I'm depending upon them never staying solid on, then I really better never write code (or hang the microcontroller) with them solid on, lest I cook my IR emitters.*
- PWM on the uC turned on and off to gate it.
- PWM gated at the i/o (turning the output to a pulled input aught to do it.)
- Externally generated carrier externally gated (seems a waste of additional circuitry when my uC choices all have PWM / Counters / Timers galore.)
*This inspires an additional functional mode: IR Flashlight. Is it useful as a flashlight strobing at 40KHz, with the carrier just constantly on? Or is there any other frequency that would be better? Something that *doesn't* alias with camera imagers or video frame rates, presumably, as those are what I'd be using to view the invisible illumination...
Question: Which uC do I want to use on this thing? Driving factors: Power consumption (for battery life), user interface, programming environment.
Question: Do the IR Receivers depend upon the carrier remaining consistently in phase with itself over time? And do they care about runt-pulses if the signal is turned out mid-way through the carrier on-time? (i.e. Do I want a synchronizer for sending data with only integer numbers of in-phase carrier pulses?)
LED switching: NPN transistor... What about current limiting to the LEDs? Do I just direct connect the LED and depend upon a BJT + voltage rail to limit the forward current? Or include a small current limiting resistor? (Built a spreadsheet, and possibly breadboard this up or SPICE it to see performance over ranges of voltage, etc, etc.)
Question: What is my LED failure mode? If it is just thermal, could I mitigate it by heat sinking them? The LED datasheet calls out operating modes of much lower duty cycles (like 1%) with much higher current (like 1A) which suggests that it is not magnetostrictive failure of the bonding leads...
Also need a housing... Want to find something fairly rugged, that holds 4AA, with enough room for a small PCB for electronics, and enough front end face space for the LEDs and enough top face space for a good UI. Button pad? LCD display? Dunno yet...
Thursday, October 21, 2010
Wednesday, October 20, 2010
Make vs. Buy
When I have some project I'm working on, I will often err on the side of building things that I really should try to just buy pre-made. The most recent example of this was when I wanted to wall-power a canon point and shoot camera that I've had lying around. I wanted to do some time-lapse experiments with it without worrying about the batteries dying. I went to HSC and rooted around in the barrel connector bins until I found one approximately the right size to fit the DC input on the camera. Then I rooted around in my box of AC adapters at home, until I decided I didn't have anything quite right, so I headed back to HSC, and bought a regulated supply of the right voltage. But then I discovered that the supply I bought couldn't meet the peak current requirements of the camera. So I started thinking that I could just use a higher current, higher voltage power supply, and built an additional switching regulator circuit to get the proper voltage at the current level the camera needs. At this point I was several hours and probably $20 in gas and parts into this project. What I *should* have done, right at the start, is gone to eBay and searched for "AC Canon Adapter A540". When I did that, I found an electronics import-export company that sells a third-party equivalent to the Canon AC power adapter for $11.49, with free shipping. I ordered one, and had it later that week.
The inclination to build, even when I should just buy, is related to the inclination to tinker, and a desire to know exactly what's going on inside the box. If I buy a power supply, I get a few high level specifications. If I build it, I know EXACTLY what's going on in there. But the cost of the time spent being a control freak far outweighs the likely benefit knowing all the details. Indeed, most complex systems simply can't be understood, in total, by one person. There are some polymaths that come close, but most significant advancements come by building on the existing hierarchy of infrastructure, and driving deep into one area of specialization. Of course, like all things, there is a balance to be maintained. Good software engineers understand enough of the conceptual internals of a compiler to know how to avoid writing pathological code. The don't necessarily know all the details, but they know the parts they need to know. And that's another trick: figuring out which are those necessary parts.
And to borrow a line from Forrest Gump, "That's all I have to say about that." I could delve much deeper into this topic, but I'm kinda tired, and want to catch up on my sleep. Goodnight.
The inclination to build, even when I should just buy, is related to the inclination to tinker, and a desire to know exactly what's going on inside the box. If I buy a power supply, I get a few high level specifications. If I build it, I know EXACTLY what's going on in there. But the cost of the time spent being a control freak far outweighs the likely benefit knowing all the details. Indeed, most complex systems simply can't be understood, in total, by one person. There are some polymaths that come close, but most significant advancements come by building on the existing hierarchy of infrastructure, and driving deep into one area of specialization. Of course, like all things, there is a balance to be maintained. Good software engineers understand enough of the conceptual internals of a compiler to know how to avoid writing pathological code. The don't necessarily know all the details, but they know the parts they need to know. And that's another trick: figuring out which are those necessary parts.
And to borrow a line from Forrest Gump, "That's all I have to say about that." I could delve much deeper into this topic, but I'm kinda tired, and want to catch up on my sleep. Goodnight.
Tuesday, October 19, 2010
Scald Burns
This is a classic chain-of-events accident. If she had been able to eat the regular dinner, she wouldn't have made macaroni and cheese. If she hadn't misread the instructions, she probably wouldn't have splashed her hand, causing the larger hot water spill. If she hadn't been wearing conforming nylon softball pants, the water may well have just soaked her clothes but not stuck to the skin. But everything lined up for a catastrophic accident. The one causal factor that we really should have seen coming, however, was the temperature of the water coming out of the hot water dispenser. Most of these dispensers put out water at temperatures between 140 and 195 degrees Fahrenheit. Indeed, the one we had didn't even have a thermostat to adjust the temperature. It was fixed, and when I tested it later, it was at about 165 degrees. This temperature is chosen for the convenient making of tea or other hot drinks. But it is also surprisingly dangerous.
Scald burns can occur at temperatures as low as 120 degrees. The time to injury decreases as the temperature increases. And children get injured faster than adults. With 160 degree F water, an adult will suffer second and third degree burns in as little as half a second, and children will suffer third degree burns in as little as 0.2 seconds. This was, I'm sad to say, news to me.
 | ||||
X Axis: Time in Seconds to Injury, Y Axis: Temp in Degrees Fahrenheit.
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I can understand that the convenience of quick hot beverages makes this a perfectly acceptable risk to people who are aware of it. The problem is all the people, like us, who were completely unaware of how fast injury can occur, and how serious it can be. These dispensers absolutely should not be where small children can get at them, and older children and adults should be taught just how dangerous the hot water coming out of them is.
Another critical bit of information most people lack is how to treat burns once they happen. What should you put on a burn? The answer is "cool water, and nothing else." Actually, if you have sterile medical saline immediately available, you can use that to irrigate the burn area. But unless you have sterile saline, use cool tap water. Never put any sort of spray, ointment, or home remedy on a burn. And if you're not sure if you should call 911, do it. Burns are serious injuries, requiring immediate care, careful professional treatment, and sterile isolation. Even "minor" burns, if they break the skin, should be carefully cleaned and bandaged, in order to prevent infection and a host of secondary complications. Err on the side of caution.
Because my daughter's burns were uncontaminated when she arrived at the hospital, they were able to use a beta-glucan collagen matrix dressing on them, which was at that time a relatively new treatment. As a result, she suffered through far fewer dressing changes than if she had gone through regular daily bandage changes, and her legs healed with almost no visible scarring. She was extremely fortunate, and she is now a vocal opponent of the use of any sort of "burn cream" or other treatment that can make the kind of outcome she enjoyed impossible.
Scald burns are the number one type of burn accident among children. The Alisa Ann Ruch Burn Foundation launched an information campaign several years ago called "Hot Liquids Burn Like Fire." If you know someone that has a hot water dispenser, tell them about this. Spread the word. Burns are horrible, and often, they are preventable.
Monday, October 18, 2010
Conspiracy Theories
I have worked at several publicly traded companies in the course of my career. At those companies, I was usually motivated to have at least some interest in what was happening to the stock price. Monitoring the stock quote online would often bring me into incidental contact with the online forums discussing the company and its stock. It was there that I saw first hand the wonderful wackiness of conspiracy theories.
People would weave elaborate speculations about how we clearly had our next three generations of products already developed, and we were carefully regulating our product introductions to manipulate the price of the stock, and to generate the best possible return for the senior management shareholders. When we did something bone-headed, it was some nefarious scheme to sew confusion in the market place, in anticipations of our next countering parry. And when some bit of news broke our way, it was because our behind-the-scenes machinations had come to fruition, and the genius of our master plan was slowly becoming evident.
The explanation that nobody was particularly interested in talking about was that we were working as fast as we could to release cool products as soon as possible so that we'd make enough money to be doing the same things this time next year. Our "mistakes" were actually the result of... mistakes. Our lucky breaks were the normal statistical distribution of events. Did we know what we planned on releasing in our next generation of products? Sort of. But we also knew that those plans would be radically modified, often until the last possible moment before shipping product, and many products that we got far into development on would never see the light of day.
It was, for me, a wonderful illustration of the reality of most conspiracy theories. They can sound plausible when you're on the outside, but when you're on the inside, you understand that there is nowhere near that degree of control being exercised by anyone. But, you say, maybe I was just an unknowing pawn in the carefully structured plans of my corporate puppet masters. Maybe. But unless they had completely separate development teams, working in different buildings, with different design repositories (which they didn't), I had pretty good visibility, even as a minion, into everything going on in engineering.
I tend to suspect that most other conspiracy theories are, like those I was speculated to be a part of, are just smoke and mirrors and the human ability to see patterns in chaos. The world is random and messy and hard to predict when you're trying to, and there usually isn't a secret deeper level of manipulation going on below the surface. Sometimes there may be, but not nearly as often as a lot of people seem determined to believe.
(... Or maybe that's exactly what they WANT you to believe. :)
People would weave elaborate speculations about how we clearly had our next three generations of products already developed, and we were carefully regulating our product introductions to manipulate the price of the stock, and to generate the best possible return for the senior management shareholders. When we did something bone-headed, it was some nefarious scheme to sew confusion in the market place, in anticipations of our next countering parry. And when some bit of news broke our way, it was because our behind-the-scenes machinations had come to fruition, and the genius of our master plan was slowly becoming evident.
The explanation that nobody was particularly interested in talking about was that we were working as fast as we could to release cool products as soon as possible so that we'd make enough money to be doing the same things this time next year. Our "mistakes" were actually the result of... mistakes. Our lucky breaks were the normal statistical distribution of events. Did we know what we planned on releasing in our next generation of products? Sort of. But we also knew that those plans would be radically modified, often until the last possible moment before shipping product, and many products that we got far into development on would never see the light of day.
It was, for me, a wonderful illustration of the reality of most conspiracy theories. They can sound plausible when you're on the outside, but when you're on the inside, you understand that there is nowhere near that degree of control being exercised by anyone. But, you say, maybe I was just an unknowing pawn in the carefully structured plans of my corporate puppet masters. Maybe. But unless they had completely separate development teams, working in different buildings, with different design repositories (which they didn't), I had pretty good visibility, even as a minion, into everything going on in engineering.
I tend to suspect that most other conspiracy theories are, like those I was speculated to be a part of, are just smoke and mirrors and the human ability to see patterns in chaos. The world is random and messy and hard to predict when you're trying to, and there usually isn't a secret deeper level of manipulation going on below the surface. Sometimes there may be, but not nearly as often as a lot of people seem determined to believe.
(... Or maybe that's exactly what they WANT you to believe. :)
Sunday, October 17, 2010
Business Idea: Self-Education University
The spread of broadband Internet connectivity means that more and more people have access to a fantastic amount of freely available educational material. Stanford Engineering is putting classes online for free. MIT has put a number of their courses online, also for free, as part of their Open Courseware initiative. Khan Academy offers a huge number of video tutorials. There are several groups approaching the idea of Open Source Textbooks. The democratization of information that began with the printing press has accelerated dramatically in the last decade, and it is now possible for someone with the determination and focus to get a really great college level education almost entirely for free.
Furthermore, as the economy stagnates, the pursuit of education during periods of unemployment or underemployment offers people with spare time an opportunity to fill their hours at minimal cost with activity that offers potential long term returns. Even if you can afford to "go back to school," you can keep learning without the benefit of a formal university structure.
One thing that a university degree offers, however, that you can't get on your own, is verification of an education. When someone has a diploma, it means that they were able to at least meet the bare minimum requirements for issuance of a degree by that university. If the university is, in turn, accredited, then you know that is has been scrutinized to insure that the curriculum meets at least minimal agreed upon standards of quality for a college education. The accredited university degree implies a great deal of backing.
When I'm interviewing a candidate for an engineering job, I want to know that they have, at least at some point in the past, acquired general engineering level math skills, such as an understanding of differential and integral calculus. If they have an engineering degree, I am usually safe to assume that they have had that exposure. I don't need to ask them specific calculus trivia to make sure. Likewise, an engineering degree implies a certain degree of breadth and exposure to structured problem solving that I want.
So what then of my self-educated candidate? If someone has taught themselves calculus by working through a plethora of online tutorials and work sheets and downloaded text books, how can I know that they really have the skills? And that's the business idea here... A series of testing centers which provide people the chance to demonstrate college level proficiency in a number of topics, by taking written tests in a secure and controlled environment. Essentially, it is like the AP tests, although you would be able to take them at any time you want. When you take a test in a topic, you receive a numeric grade, say from 0-100, indicating how you did. The test would be designed such that a reasonably high score, say 80, would indicate general proficiency, essentially a high likelihood of passing a college course in that topic. If you pass enough subject tests, they can be clustered together into a portfolio that essentially becomes your college-degree transcript equivalency. This would provide something that can be validated by the testing center to employers or other schools, indicating that you have the education you claim to have.
There are some obvious shortcomings between this and the real college experience. First off is the social. You know that someone who has gone through college has probably managed to work at least a little bit with other people, whereas someone could work though a degree worth of college level material, testing along the way and never talk to another individual. I don't really see any quick ways around this. This certification simply lacks any useful social metric.
Another limitation is project work. Often in college classes, the final product of the work is an almost incidental part of the process, which is the real learning experience. The product that results from a project course is also difficult to objectively evaluate in the way that this testing center approach would need to do. Furthermore, an important part of this testing center concept is that you clearly know that the person who walked in the door is the person that did the work, because they took the test there while you watched them, after you fingerprinted them, or did whatever other level of validation was decided appropriate to match the person with the educational certification. With any submission of outside materials, the provenance of that material is open to question, and brings into question the integrity of the resulting certification.
Even with these and other weaknesses, it seems that this is something that could be really big, especially for people who are motivated to get a degree-level education but can't afford the money, or perhaps even the structured time, of attending a college or university. Key to the acceptance of an approach like this would be maintaining the integrity of the testing. And there would be skepticism at first. But in time, I think, it would become at least as accepted as a "college level GED," and possibly eventually seen as a perfectly normal alternative to the "traditional" college experience, in some ways all the more impressive for the level of self-motivation and personal drive it represents.
Furthermore, as the economy stagnates, the pursuit of education during periods of unemployment or underemployment offers people with spare time an opportunity to fill their hours at minimal cost with activity that offers potential long term returns. Even if you can afford to "go back to school," you can keep learning without the benefit of a formal university structure.
One thing that a university degree offers, however, that you can't get on your own, is verification of an education. When someone has a diploma, it means that they were able to at least meet the bare minimum requirements for issuance of a degree by that university. If the university is, in turn, accredited, then you know that is has been scrutinized to insure that the curriculum meets at least minimal agreed upon standards of quality for a college education. The accredited university degree implies a great deal of backing.
When I'm interviewing a candidate for an engineering job, I want to know that they have, at least at some point in the past, acquired general engineering level math skills, such as an understanding of differential and integral calculus. If they have an engineering degree, I am usually safe to assume that they have had that exposure. I don't need to ask them specific calculus trivia to make sure. Likewise, an engineering degree implies a certain degree of breadth and exposure to structured problem solving that I want.
So what then of my self-educated candidate? If someone has taught themselves calculus by working through a plethora of online tutorials and work sheets and downloaded text books, how can I know that they really have the skills? And that's the business idea here... A series of testing centers which provide people the chance to demonstrate college level proficiency in a number of topics, by taking written tests in a secure and controlled environment. Essentially, it is like the AP tests, although you would be able to take them at any time you want. When you take a test in a topic, you receive a numeric grade, say from 0-100, indicating how you did. The test would be designed such that a reasonably high score, say 80, would indicate general proficiency, essentially a high likelihood of passing a college course in that topic. If you pass enough subject tests, they can be clustered together into a portfolio that essentially becomes your college-degree transcript equivalency. This would provide something that can be validated by the testing center to employers or other schools, indicating that you have the education you claim to have.
There are some obvious shortcomings between this and the real college experience. First off is the social. You know that someone who has gone through college has probably managed to work at least a little bit with other people, whereas someone could work though a degree worth of college level material, testing along the way and never talk to another individual. I don't really see any quick ways around this. This certification simply lacks any useful social metric.
Another limitation is project work. Often in college classes, the final product of the work is an almost incidental part of the process, which is the real learning experience. The product that results from a project course is also difficult to objectively evaluate in the way that this testing center approach would need to do. Furthermore, an important part of this testing center concept is that you clearly know that the person who walked in the door is the person that did the work, because they took the test there while you watched them, after you fingerprinted them, or did whatever other level of validation was decided appropriate to match the person with the educational certification. With any submission of outside materials, the provenance of that material is open to question, and brings into question the integrity of the resulting certification.
Even with these and other weaknesses, it seems that this is something that could be really big, especially for people who are motivated to get a degree-level education but can't afford the money, or perhaps even the structured time, of attending a college or university. Key to the acceptance of an approach like this would be maintaining the integrity of the testing. And there would be skepticism at first. But in time, I think, it would become at least as accepted as a "college level GED," and possibly eventually seen as a perfectly normal alternative to the "traditional" college experience, in some ways all the more impressive for the level of self-motivation and personal drive it represents.
Saturday, October 16, 2010
Habit Formation
Executive summary: Do not read this post. Come back tomorrow. You are warned.
I have heard it said that an activity must be carried out daily for six week to become an ingrained habit. Well, I haven't reached six weeks yet on these daily blog entries, but I know that they have not yet become anything near an ingrained habit. I was sitting here at my desk with 13 minutes until midnight, when I really should already be asleep after being sick the last few days. I was just about to call it a day, and realized that I've not written anything today. I referred to my list of pending ideas (currently a bit thin, I should work on that tomorrow) and didn't see anything I wanted to write about (in 11 minutes or less) so here I am making stuff up off the cuff, and writing a lot of run-on sentences.
Should I, on these days when I'm neither inspired nor particularly interested, even bother writing something? That depends a lot on what I think the purpose of this writing is. If I had any delusions that I had a large regular audience (Hi Dad!) I might go for quality over quantity, and make my adoring public wait an extra day in between. But it's not all about you, people. The point of this exercise from the start has largely been about writing on deadline, cranking text out quickly, getting something out every day (more or less) and not being too picky about the quality (or incredibly self-referential, pseudo-intellectually quasi-post-modernist bent) of the writing.
I must admit, the 230+ page views that I got for last Tuesday's entry about blood donation did give me a little shot of adrenaline. People actually read my words. Maybe I could come up with even more words that even more people would want to read. And maybe I'll even try to do that someday yet. I do have a few tricks up my sleeve. But today is not that day. Today you get this. See, I told you not to read it.
I have heard it said that an activity must be carried out daily for six week to become an ingrained habit. Well, I haven't reached six weeks yet on these daily blog entries, but I know that they have not yet become anything near an ingrained habit. I was sitting here at my desk with 13 minutes until midnight, when I really should already be asleep after being sick the last few days. I was just about to call it a day, and realized that I've not written anything today. I referred to my list of pending ideas (currently a bit thin, I should work on that tomorrow) and didn't see anything I wanted to write about (in 11 minutes or less) so here I am making stuff up off the cuff, and writing a lot of run-on sentences.
Should I, on these days when I'm neither inspired nor particularly interested, even bother writing something? That depends a lot on what I think the purpose of this writing is. If I had any delusions that I had a large regular audience (Hi Dad!) I might go for quality over quantity, and make my adoring public wait an extra day in between. But it's not all about you, people. The point of this exercise from the start has largely been about writing on deadline, cranking text out quickly, getting something out every day (more or less) and not being too picky about the quality (or incredibly self-referential, pseudo-intellectually quasi-post-modernist bent) of the writing.
I must admit, the 230+ page views that I got for last Tuesday's entry about blood donation did give me a little shot of adrenaline. People actually read my words. Maybe I could come up with even more words that even more people would want to read. And maybe I'll even try to do that someday yet. I do have a few tricks up my sleeve. But today is not that day. Today you get this. See, I told you not to read it.
Friday, October 15, 2010
Home Sick
There aren't many days that I'm actually sick to the point of not being able to do some useful work, but today was basically one of those. I managed to reply to a few work e-mails, but mostly I have just been sitting around all day, or napping. It's 4:07 PM and I'm still wearing my pajamas. My energy level is low, I'm achy, and my skin feels hypersensitive to any sort of touch. I called the blood center to let them know, following my platelet apheresis on Tuesday, and they said they'll check with one of the docs, but given that the symptom onset was several days after the donation, the product should be okay.
I suspect that I've got a bug that has been going around at my office. It's almost like a cold without respiratory involvement. I'm hopeful I'll shake it off by tomorrow. I'm sucking on Cold-Eeze Zinc Gluconate lozenges every few hours. They claim to have clinical backing for their claim of shortening cold symptoms. A quick Google search lands me here, at an abstract on a study of Cold-Eeze, with several links to related studies. It looks like these studies use incidental colds, and it would be really interesting to see a controlled lab study in which they spray rhinovirus up the noses of healthy college students, and then as soon as they exhibit symptoms, give half of them Cold-eeze and the other half placebos. (These studies are, obviously, more expensive and difficult to do, especially with large test groups.)
Oooh, here's a study linking my previous musings on the power of sleep with rhinovirus susceptibility... Again, the study is fairly small, but they really did give the participants rhinovirus nose drops and then see if they got sick. The differences were pretty stark. On that note, maybe I'll go lie down again...
I suspect that I've got a bug that has been going around at my office. It's almost like a cold without respiratory involvement. I'm hopeful I'll shake it off by tomorrow. I'm sucking on Cold-Eeze Zinc Gluconate lozenges every few hours. They claim to have clinical backing for their claim of shortening cold symptoms. A quick Google search lands me here, at an abstract on a study of Cold-Eeze, with several links to related studies. It looks like these studies use incidental colds, and it would be really interesting to see a controlled lab study in which they spray rhinovirus up the noses of healthy college students, and then as soon as they exhibit symptoms, give half of them Cold-eeze and the other half placebos. (These studies are, obviously, more expensive and difficult to do, especially with large test groups.)
Oooh, here's a study linking my previous musings on the power of sleep with rhinovirus susceptibility... Again, the study is fairly small, but they really did give the participants rhinovirus nose drops and then see if they got sick. The differences were pretty stark. On that note, maybe I'll go lie down again...
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