So I know the next installment of Basic Physics is several weeks overdue, but there has been so much going on I haven't had time to do it justice. So here's a post on what's been going on!
Firstly, my first paper got accepted for publication! This is a research project that I had been fighting for well over a year, and the results were/are really cool. It's also my first first author paper, which is a really big deal in the sciences (at least my branch of the sciences). I don't know of an equivalent outside of research circles.
I'm working on new but related research projects, which will hopefully bear fruit soon.
DH got a job in a city that is just far enough away to make commuting 5 days a week untenable, so we are slowly transitioning our lives to an apartment in new city, with me getting the house ready to rent out in our old city. So, ya know, that's a bit time and energy consuming.
I'm teaching half time this semester, which is great, but eats my Thursdays between prep and teaching and seminar and teaching and then eats a couple hours not on Thursdays for grading and getting lesson plans and weekly tests ready for myself and the other two TAs to use.
I have to write and present and get approved a prospectus/research plan by the end of the semester or get kicked out. It is the vaguest most important piece of writing I have to do to date.
I'm also attending the Frontiers in Optics conference in October! Which is going to be fantastic and exhausting and in Arizona! It's also forcing me to actually get some more 'professional' looking clothes, which for me basically means I didn't make them and/or I couldn't rake leaves in them. I am not going to be removing my earrings unless my advisor specifically says otherwise though. They are a part of me, and besides my hair provides decent camouflage.
I also seem to be morphing into a high classical-christianity Anglican instead of a good Calvinist-Presbyterian, and I have to write a separate post on that.
So you can see, there is A LOT going on my life right now, so if the postings are a bit thin on the ground, hopefully you can forgive me.
Cheers!
Showing posts with label North Carolina. Show all posts
Showing posts with label North Carolina. Show all posts
Wednesday, September 10, 2014
Friday, May 23, 2014
What makes a light source safe?
Working in a science comes with an occupational hazard of head-slapping. It doesn't matter how tolerant, how understanding you are of the fact that not everyone is a scientist and therefore lacks some of the insight that we take for granted. On a semi-regular basis, you find yourself face-palming, banging your head against a wall and generally weeping for the scientific literacy of humanity. Whether it's a friend from college who has gone all homeopathic, a movie with impossible physics or a local news item that gets you to scream at the television, it's part of the territory.
Which is why I couldn't be all that surprised when, upon complimenting a coworker's manicure, I learned that her mother had gotten a free UV nail lamp because the cosmetology board had decided to replace all their old bulb UV lamps with LED light sources because they were 'safer'. My coworker laughed as she told me this, because we both know that it doesn't matter if your UV light is naturally emitted from unicorn horns fed only the most organic of herbage, it's still UV light and it can still give you cancer.
So, what makes a light source 'safe'? It depends, in part, on what you are using the light source for.
For example, in your house, you want a light bulb that isn't going to set your house on fire, explode, or release toxic gases. You aren't really worried about whether they can give you cancer, because the light they output is in the visible range, and sometimes into the infrared, all of which is non-ionizing. There are three options widely available to average person these days. There is old school incandescent bulbs, halogen bulbs and LED bulbs.
Incandescent are familiar, and what most people alive today grew up with. They have a filament that glows white hot when you pass a current through them. They do not have any toxic gases and most people seem to think of them as the non-toxic bulb (though the tungsten in the filament is highly toxic, it's sitting there and who is going to lick it?) But it's incredibly energy inefficient. Most of the energy it uses goes to heat (infrared), not visible light. You can burn yourself by touching one that's been on a little while, and they can explode from thermal shock if you accidentally sneeze on one that has been on long enough to get hot (yes, I have done this).
Halogens are becoming more familiar. They work just like any good old fluorescent bulb, with less flickering, by exciting electrons in a diffuse gas until they give off light, which then excites a coating on the bulb into giving white light. They are more energy efficient since heat is a byproduct and not the means of producing light, but they aren't hugely more efficient and they contain small amounts of mercury. They have to be disposed of properly at hardware stores or recycling centers, and it's not clear what you should do if one breaks.
LEDs are the newest contenders. They use light emitting diodes to create light, which means they are semiconductor based. Semiconductors aren't the nicest things in the world to make, but they are not toxic if they break. They are very efficient (some of the better ones barely get warm) and very pricey. They have by far the longest lifespan, and are probably the nicest looking.
So for safety, in my house, I am switching over to LED bulbs as each of the other style bulbs give up the ghost. Lower fire risk and no risk of mercury poisoning. This is what a safe bulb in my house means.
But the safety question when it comes to things like tanning beds and nail polish curing is very different. The customer is unlikely to have to deal with broken bulbs and they aren't immediately concerned with the energy efficiency or fire risk. The questionable safety of such devices arises from the specific wavelengths of light used, namely ultraviolet or UV light.
UV light exposure is concerning over long periods because the wavelength of UV is small enough to interact with DNA molecules and energetic enough to damage them. When DNA gets damaged, it leads to mutations, some of which are harmless and others that can be very harmful indeed.
Now, we can put this to good use in sterilizers using UV-C, because it doesn't involve chemicals that might be dangerous to us or that bacteria might grow resistant to. The light destroys the bacteria from the inside, like someone smashing your hard drive and motherboard would effectively destroy your computer. This is a good use of UV light.
UV light can be produced by any number of bulb types, including fluorescent bulbs, lasers of various types and LEDs. Older models of nail lamps used fluorescent bulbs, which are relatively cheap and give even light coverage.
So does switching over to a different type of bulb make it any safer for people who want to use these lamps? Nope. So long as they are using the same polymers that require the same wavelength of UV light to cure, the LED bulbs will be giving off the same UV radiation as the old bulbs.
How safe are any of these nail lamps? Depends on who you ask. It is difficult to predict cancer risks in any population. This letter to the Journal of the American Academy of Dermatology suggests that, at least for the two national brand models they tested, in three minutes your hands are getting the equivalent of 4-6 hours of allowable UV exposure for construction workers. Each lamp puts out over 4 times the amount of UV energy than the sun. So while using them on occasion won't bring any more risk than staying outside in the sun all day, you may not want to use them on a regular basis.
Me, I'd rather get my skin cancer risk from taking a walk on a nice day.
Which is why I couldn't be all that surprised when, upon complimenting a coworker's manicure, I learned that her mother had gotten a free UV nail lamp because the cosmetology board had decided to replace all their old bulb UV lamps with LED light sources because they were 'safer'. My coworker laughed as she told me this, because we both know that it doesn't matter if your UV light is naturally emitted from unicorn horns fed only the most organic of herbage, it's still UV light and it can still give you cancer.
So, what makes a light source 'safe'? It depends, in part, on what you are using the light source for.
For example, in your house, you want a light bulb that isn't going to set your house on fire, explode, or release toxic gases. You aren't really worried about whether they can give you cancer, because the light they output is in the visible range, and sometimes into the infrared, all of which is non-ionizing. There are three options widely available to average person these days. There is old school incandescent bulbs, halogen bulbs and LED bulbs.
Incandescent are familiar, and what most people alive today grew up with. They have a filament that glows white hot when you pass a current through them. They do not have any toxic gases and most people seem to think of them as the non-toxic bulb (though the tungsten in the filament is highly toxic, it's sitting there and who is going to lick it?) But it's incredibly energy inefficient. Most of the energy it uses goes to heat (infrared), not visible light. You can burn yourself by touching one that's been on a little while, and they can explode from thermal shock if you accidentally sneeze on one that has been on long enough to get hot (yes, I have done this).
Halogens are becoming more familiar. They work just like any good old fluorescent bulb, with less flickering, by exciting electrons in a diffuse gas until they give off light, which then excites a coating on the bulb into giving white light. They are more energy efficient since heat is a byproduct and not the means of producing light, but they aren't hugely more efficient and they contain small amounts of mercury. They have to be disposed of properly at hardware stores or recycling centers, and it's not clear what you should do if one breaks.
LEDs are the newest contenders. They use light emitting diodes to create light, which means they are semiconductor based. Semiconductors aren't the nicest things in the world to make, but they are not toxic if they break. They are very efficient (some of the better ones barely get warm) and very pricey. They have by far the longest lifespan, and are probably the nicest looking.
So for safety, in my house, I am switching over to LED bulbs as each of the other style bulbs give up the ghost. Lower fire risk and no risk of mercury poisoning. This is what a safe bulb in my house means.
But the safety question when it comes to things like tanning beds and nail polish curing is very different. The customer is unlikely to have to deal with broken bulbs and they aren't immediately concerned with the energy efficiency or fire risk. The questionable safety of such devices arises from the specific wavelengths of light used, namely ultraviolet or UV light.
UV light exposure is concerning over long periods because the wavelength of UV is small enough to interact with DNA molecules and energetic enough to damage them. When DNA gets damaged, it leads to mutations, some of which are harmless and others that can be very harmful indeed.
Now, we can put this to good use in sterilizers using UV-C, because it doesn't involve chemicals that might be dangerous to us or that bacteria might grow resistant to. The light destroys the bacteria from the inside, like someone smashing your hard drive and motherboard would effectively destroy your computer. This is a good use of UV light.
UV light can be produced by any number of bulb types, including fluorescent bulbs, lasers of various types and LEDs. Older models of nail lamps used fluorescent bulbs, which are relatively cheap and give even light coverage.
So does switching over to a different type of bulb make it any safer for people who want to use these lamps? Nope. So long as they are using the same polymers that require the same wavelength of UV light to cure, the LED bulbs will be giving off the same UV radiation as the old bulbs.
How safe are any of these nail lamps? Depends on who you ask. It is difficult to predict cancer risks in any population. This letter to the Journal of the American Academy of Dermatology suggests that, at least for the two national brand models they tested, in three minutes your hands are getting the equivalent of 4-6 hours of allowable UV exposure for construction workers. Each lamp puts out over 4 times the amount of UV energy than the sun. So while using them on occasion won't bring any more risk than staying outside in the sun all day, you may not want to use them on a regular basis.
Me, I'd rather get my skin cancer risk from taking a walk on a nice day.
Monday, April 28, 2014
Gardening Success!
It took two good days of two person gardening, but our front yard now officially looks like it belongs to real people. It took 60 bales of pine needles to cover the whole area (and we probably could have used 70, coverage is a little thin in some areas). All the privet hedges got planted, weeds (including two saplings) got pulled, over all a great success.
Don't get me wrong, it still needs work. We need to find something to replace the monkey grass down at the bottom of the hill, where it is not doing so well in 'the swamp'. We're testing out two small 'willow' shrubs to see how they fare in that area. The azaleas are questionable. And I am currently on the war path against inchworms in my shrubs. If they want to eat the trees or the weeds, fine. I'd even be ok with them eating the azaleas. But not my new to-be hedge. A sparing and localized treatment of pesticide seems to have deterred them for the moment. I don't like using pesticide, but I also don't like watching tiny worms eat a fairly substantial investment in time and money. I'm using it as a stopgap until I can get my hands on some Bt pesticide--kills any insect that eats my leaves, none that don't, harmless to non-bugs and becomes inert after a week of sunshine.
In other news, I've learned that gardening and in general being outside in my yard right now requires some clever use of scarves. Bandanas make for great improvised dust masks when spreading pine needles...
And my old tichels make for great inchworm barriers. There is few things more creepy than an inchworm in my hair.
I'm fairly certain I look a bit out of place in my neighborhood with it on, but that's nothing new, and its worth it to know there are no inchworms landing in my hair.
Overall, a successful weekend.
Don't get me wrong, it still needs work. We need to find something to replace the monkey grass down at the bottom of the hill, where it is not doing so well in 'the swamp'. We're testing out two small 'willow' shrubs to see how they fare in that area. The azaleas are questionable. And I am currently on the war path against inchworms in my shrubs. If they want to eat the trees or the weeds, fine. I'd even be ok with them eating the azaleas. But not my new to-be hedge. A sparing and localized treatment of pesticide seems to have deterred them for the moment. I don't like using pesticide, but I also don't like watching tiny worms eat a fairly substantial investment in time and money. I'm using it as a stopgap until I can get my hands on some Bt pesticide--kills any insect that eats my leaves, none that don't, harmless to non-bugs and becomes inert after a week of sunshine.
In other news, I've learned that gardening and in general being outside in my yard right now requires some clever use of scarves. Bandanas make for great improvised dust masks when spreading pine needles...
 |
| And makes me look like classical music loving old-west bandit |
 |
| Tichels--really really big bandanas with prettier patterns |
I'm fairly certain I look a bit out of place in my neighborhood with it on, but that's nothing new, and its worth it to know there are no inchworms landing in my hair.
Overall, a successful weekend.
Monday, April 14, 2014
Windows, definitions 1 and 2
Last week has somehow ended up focused on two kinds of windows--the kind that let me see the outside world from inside my house and the kind that provides the operating system to my computers at school.
It was discovered a couple of months ago that one of our windows, one in my home office to be specific, was rotting out. Shortly after that I discovered one of our bedroom windows was rotting out. It looked like someone had just painted over existing wood rot instead of replacing the sills, leading the the entire thing rotting. Because both culprits are in bays, we were looking at least 6 windows needing replacement.
So we called the local Anderson windows dealer, who discovered two more heavily rotting windows. These are windows that we never look out of since they just look into our neighbors windows and we can't easily see from the ground, but even we could see (when the blinds were drawn) that they looked like they belonged in a haunted mansion.
Hello custom, rot-proof windows. Goodbye nice vacation.
At school/work, IT is going crazy about replacing XP computers with Windows 7 computers. Yes, they are replacing the incredibly out of date operating system with a slightly less out of date operating system.
For most people, this is good news. Faster computers. New monitors, etc.
This is horrible for any sort of researcher. Custom software. Very expensive proprietary software that only allows one installation and is necessary to run a very expensive piece of equipment. Data that you don't want to run even the slightest chance of losing because that there's 4 years worth of work. For a theoretician, everything applies except the equipment.
Needless to say, most of us were trying hard to hide our computers and ignoring emails and personal inspections by the department IT guy.
I finally had to give in because the XP computers were going to be cut off from internet, and the program I depend on to produce graphs requires an internet connection, the stupid thing. But I'm keeping my old one, off network, lest I lose anything.
I was really excited to have two monitors at last. If only the new one actually worked.
Oh well, maybe I can get graphs in less than 2 hours computation time now.
It was discovered a couple of months ago that one of our windows, one in my home office to be specific, was rotting out. Shortly after that I discovered one of our bedroom windows was rotting out. It looked like someone had just painted over existing wood rot instead of replacing the sills, leading the the entire thing rotting. Because both culprits are in bays, we were looking at least 6 windows needing replacement.
So we called the local Anderson windows dealer, who discovered two more heavily rotting windows. These are windows that we never look out of since they just look into our neighbors windows and we can't easily see from the ground, but even we could see (when the blinds were drawn) that they looked like they belonged in a haunted mansion.
Hello custom, rot-proof windows. Goodbye nice vacation.
At school/work, IT is going crazy about replacing XP computers with Windows 7 computers. Yes, they are replacing the incredibly out of date operating system with a slightly less out of date operating system.
For most people, this is good news. Faster computers. New monitors, etc.
This is horrible for any sort of researcher. Custom software. Very expensive proprietary software that only allows one installation and is necessary to run a very expensive piece of equipment. Data that you don't want to run even the slightest chance of losing because that there's 4 years worth of work. For a theoretician, everything applies except the equipment.
Needless to say, most of us were trying hard to hide our computers and ignoring emails and personal inspections by the department IT guy.
I finally had to give in because the XP computers were going to be cut off from internet, and the program I depend on to produce graphs requires an internet connection, the stupid thing. But I'm keeping my old one, off network, lest I lose anything.
I was really excited to have two monitors at last. If only the new one actually worked.
Oh well, maybe I can get graphs in less than 2 hours computation time now.
Thursday, April 3, 2014
Final stretch of the semester, running on fumes
It happens pretty much every semester, as Dear Husband pointed out to me this morning when I said I just wanted the semester to be over already. I start out the semester with plenty of energy to form new minds, until we reach the last few weeks when I start to feel depressed about their lack of commitment to learning, their lack of understanding, and how utterly horrible it is to grade 3000 final exams written by undergrads who may or may not understand that physics requires math, and therefore can't be fluffed out of.
Basically, I feel like this:
Basically, I feel like this:
 |
| Can we be done now? |
It's not a place I like to be. And usually, this feeling occurs between teaching. Once I'm actually in the classroom, the students remind me why I love teaching, I get in the zone and I will happily teach for the hour+ that I'm given.
But this semester, three out of four of my classes are duds. The students are disengaged with learning. They don't ask questions. Lower admissions requirements on the part of the university mean that the level of mathematical literacy is astoundingly lower than I'm used to. Because we reinstated weekly in-class paper quizzes instead of online weekly quizzes we did last semester, I have to deal with a whole crop of students who never learned the importance of drawing diagrams for every problem, even if they can solve it without, and who fight me constantly for the 2-3 points I dock if they don't draw one. In the past, students have looked at it as "woohoo, 2-3 free points, yeah!"; this semester, I was told I was "teaching my philosophy, not physics". Nevermind that this is standard and still required of problems well into grad school.
One class is not like this. One class is wonderful and a joy to teach.
But it's hard to make up for the three classes where I walk in and get less energized because the students just aren't there, mentally.
In short, I can't wait for the semester to be over.
Friday, March 21, 2014
A Hectic Week
This week has been a rather hectic week for me, though not in crazy-running-around kind of way.
Teaching has been more time consuming and emotionally difficult because we had a series of schedule mishaps (including a snow day), combined with a class that seems to need a little more hand holding through the topics than usual. The result is I have to spend more time prepping, and a lot more time grading.
If a quiz is done correctly, it is usually obviously correct.
When it is wrong, it can be obviously wrong (blank page, doodles, completely unrelated equations, etc) or very very creatively wrong, or completely wrong in execution, but correct in the theory, or the execution is done completely correctly, but with the wrong theory. It can be very difficult to grade the creatively wrong quizzes.
In addition to teaching, on Wednesday, I volunteered to host a prospective grad student for the afternoon and evening. It was a lovely time, and I enjoyed it very much, but it did throw my usual schedule a little out of whack.
And now we are awaiting the arrival of the flight bearing my mother-in-law, who will be visiting a week. Her flight is unfortunately delayed, and we aren't sure if we should try to catch some sleep, or stay awake in case things change. We seem to have defaulted to the later.
A fitting end to a hectic, but good, week.
Teaching has been more time consuming and emotionally difficult because we had a series of schedule mishaps (including a snow day), combined with a class that seems to need a little more hand holding through the topics than usual. The result is I have to spend more time prepping, and a lot more time grading.
If a quiz is done correctly, it is usually obviously correct.
When it is wrong, it can be obviously wrong (blank page, doodles, completely unrelated equations, etc) or very very creatively wrong, or completely wrong in execution, but correct in the theory, or the execution is done completely correctly, but with the wrong theory. It can be very difficult to grade the creatively wrong quizzes.
In addition to teaching, on Wednesday, I volunteered to host a prospective grad student for the afternoon and evening. It was a lovely time, and I enjoyed it very much, but it did throw my usual schedule a little out of whack.
And now we are awaiting the arrival of the flight bearing my mother-in-law, who will be visiting a week. Her flight is unfortunately delayed, and we aren't sure if we should try to catch some sleep, or stay awake in case things change. We seem to have defaulted to the later.
A fitting end to a hectic, but good, week.
Friday, February 21, 2014
Micro Flash Flooding
One of the fun/scary things about living in this part of the world is the crazy thunderstorms we can get any time of the year. They are a lot of fun to watch, and they dump a terrific amount of water in a very short time. Which of course can lead to flash floods.
Our house is set on a slope, and this leads to some interesting water situations. Our patio/driveway are sloped slightly towards the house, because they are supposed to drain into a drainage channel/french drain that runs along the . Only problem is the drainage channel gets clogged with dirt/leaves easily and the french drain was ruined by the previous owner. Our front yard contains what is technically a dry stream bed that fills and drains into the active stream in our neighbor's yard. There is a large pipe under our driveway to allow it to flow when it does rain.
That tan stuff is water.
It was an inch and a half (about 4 cm) deep at my back step
It filled our driveway...
And out front, the streambed was no longer dry
About an hour later, all the water was gone, with no visible sign of it ever having been there.
Easy come, easy go.
Our house is set on a slope, and this leads to some interesting water situations. Our patio/driveway are sloped slightly towards the house, because they are supposed to drain into a drainage channel/french drain that runs along the . Only problem is the drainage channel gets clogged with dirt/leaves easily and the french drain was ruined by the previous owner. Our front yard contains what is technically a dry stream bed that fills and drains into the active stream in our neighbor's yard. There is a large pipe under our driveway to allow it to flow when it does rain.
That tan stuff is water.
It was an inch and a half (about 4 cm) deep at my back step
It filled our driveway...
Which then flooded the garage....
And out front, the streambed was no longer dry
About an hour later, all the water was gone, with no visible sign of it ever having been there.
Easy come, easy go.
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