Just to stoke the fire, I want to point to a joint official position statement from the American Heart Association and the American College of Sports Medicine. It's online at their website: go here (I got this via an article by Gary Taubes).
Once you've got the PDF, go to page 7 of the document (page 1087 in the printed journal). Right hand column, second paragraph reads:
It is reasonable to assume that persons with relatively high daily energy expenditures would be less likely to gain weight over time, compared with those who have low energy expenditures. So far, data to support this hypothesis are not particularly compelling...
In other words, there are no good scientific studies that prove that exercise leads to weight loss.
Of course, exercise is good for you. But it won't help you lose weight.
So there. The big authorities (who surprisingly enough show scientific integrity) have said it.
Are you sure about this? Of course, it "makes sense", just like it makes sense that calorie restriction leads to weight loss. And yes, it has been said many times, so it must be true too.
To counter this assertion, I recommend a cool article by Gary Taubes (a scrupulous science writer with a low-carb bent)
in "New York" magazine. In it, he presents evidence that exercise per se doesn't lead to weight loss.
What he does say, which I find interesting, is that people are born with a certain level of activity built in. Some people are nervous rabbit-like types like me, and they never gain weight (I eat lots, and exercise little). Other people are calm and sedentary, and tend to gain weight. What he points out is that thin people are prone to be active, whereas fat people are prone to inactivity. This is an observed correlation.
At this point, we will often jump to infer a causal effect from the correlation: we will conclude that it proves that exercise leads to weight loss. This inference is especially tempting because it meshes with the energy-balance theory of weight loss.
But Taubes cites a very thorough review of exercise-weight studies, in which the Finnish authors decided the problem was "more complex" than people think. People who exercised sometimes lost weight, sometimes gained. The cause-and-effect connection isn't really there.
The equation "weight_change = calories_eaten - calories_burned" is obviously correct (it's basic physics), but the way it' usually interpreted doesn't make sense. The usual interpretation is that you have to eat less to lose weight. However, this goes against observed facts. The observed fact is that most people's weight (with small variations) remains constant, even though they make no effort to match their caloric intake to their metabolism.
The only rational explanation I can see is that metabolism adjusts to match caloric intake. The body is doing everything it can to keep body mass constant.
Looking at your post, I see that you are making several arguments in one:
People's weight varies slightly due to water loss and gain. This is true, so my initial position was overstated. I agree now that people's weight isn't straight-line constant. But lots of studies do show that people's weight does stay largely constant, modulo the minor variations you point to.
"It is simple physics", ie delta_weight = calories_in - calories_burned. Here, again, there's lots of good studies that say that this does not hold. Many fat people go on diets for years on end, eating 1500 calories per day, yet their bodies refuse to drop below a certain level. Eating 1500 calories is very hard, but these people have strong wills. They're not gluttonous moral weaklings.
Physics isn't being violated, thank god. The law of energy conservation still holds. But using a physics argument fails in this case, because the body is so adaptable. Metabolism must be adjusting to the calories being consumed. It must be going up when you eat more, and going down when you eat less. It's the only answer that fits the observed facts.
To lose weight requires that you burn more calories than you consume.
This doesn't make any sense, if you think about it. Yes, I know we've had that idea pounded into our brains for decades, but we're all techies here, and we should be able to do some math:
The amazing fact is that people's weight stays constant despite varying levels of calorie intake and exercise. The body is smart. It has had billions of years of evolution to build in mechanisms that help preserve the body in a constant form. Yes, it's true that if eat nothing you will eventually overcome those mechanisms, and lose weight, but that's not permanent. If you go back to eating normally, you will regain the weight.
There's so much morality-driven nonsense being promulgated about the virtues of exercise and caloric deprivation. But it's really just dogma that stands in the way of scientific reasoning.
Here's a simple bit of logic: a slice of bread (a mere trifle, you'll agree) has about 100 calories. Suppose your body burns X calories per day (say X=2500), and you accidentally eat one slice of bread too many. Over a year, you'll have eaten 36,500 too many calories, and since fat (body fat and also dietary fat) has 8 calories per gram, you'll have gained 36,000/8=4560 grams (about 10 pounds for you metric-deprived 'murricans).
Over 10 years, you'll gain 100 pounds! If, on the other hand, you erroneously omit that slice of bread, you'll become anorexic and probably die.
But this doesn't happen in practice! In practice, people don't hit their exact metabolic requirements every day. It's hit and miss. And yet the very well established medical fact is that most people retain the same constant weight despite a completely varying dietary intake.
Well, you'll argue that on average you'll hit the target, but why should that be so? Yes, there are people who tend to gain weight, but the vast majority of people keep their weight constant, even though their average dietary intake probably doesn't match their metabolic "ideal" exactly.
The answer is that you metabolism adjusts to match your caloric intake. Your body is way smarter than you when it comes to weight. It's gonna do its best to keep weight constant no matter how hard you try.
Go on, tell me I'm full of sh*t. But use reason. Don't spout preconceived dogma.
I don't mind being called drunk. I do mind being ignored out of hand. Did you actually read what I wrote? What part of my argument did you find illogical?
In a car, the number of Joules expended is exactly matched by the Joules taken in as gasoline. But how can you account for the fact that most people's weight remains constant despite wildly varying daily caloric intake? Doesn't that tell you that people aren't like cars?
Wake up and smell the morality-driven bad medical advice that's been promulgated for the past fifty years.
Geez people! What's happened to us all? Why do we think that exercise leads to weight loss? Why should calorie restriction lead to weight loss? It doesn't make any sense. Think about it.
Consider calorie restriction. Suppose your base metabolism is such that you burn 2000 calories per day. Let's hypothesize the (apparently obvious) premise that any calories ingested beyond this value will be stored as fat (and conversely, if you eat less than 2000, you'll burn fat).
Well, how the heck do you manage to eat exactly 2000 calories per day? It's very hard. Suppose you're off by 100 calories, which is not hard to do (eg, a slice of white bread has 80 calories). You consistently eat 100 calories too many, every day. Well, after 365 days, you'll have eaten 36,500 calories too many, and since one gram of fat has 8 calories, you'll have gained 4.5 kilos, or about 10 pounds. Keep this up for 10 years, and you'll have gained 100 pounds. Amazing!
Conversely, if you consistently eat one slice of bread too few, you'll lose 100 pounds in 10 years, and die of anorexia!
Silly, isn't it? Let's make it more random, and assume that some days you eat 100 calories too many, some days 100 too few, at random. There is a substantial probability that the surplus and the deficit will not cancel out exactly. After all, the odds of tossing a coin 365 times and have it come up HTHTHTHTHTHTHTHTHTHT... heads and tails alternating exactly, cancelling each other out, is 0.5^365, which is a very small number (about 10^-110). ANY OTHER OUTCOME LEADS TO WEIGHT LOSS OR GAIN!
So, you'd expect to see people walking around weighing thousands of pounds, or being skeletons and dying in droves.
But this doesn't happen. The observed fact is that most people hold the SAME weight for many years. The body follows a "set point".
So, something else must cause weight gain. It's certainly not calories.
Hear hear! For god's sake people, don't just go off half-cocked when you read an article. Go check the data! I've managed with little effort to pull up the county-by-county results for the 2002 Georgia gubernatorial election.
Whoah mule! Hang on! I actually RTFA (well, I tried to, but my library doesn't subscribe to "Nature News"). But, I did read the comments attached to the article summary (off the link provided in the article). They are highly critical of the claims made.
One comment also says that people have actually measured leaf temperatures directly (using thermometers, of all things): leaves can get very hot, and very cold, and that they don't usually keep a constant avg temp.
Another comment states that out that you're using ratios of oxygen isotopes to infer the average temperature. This ratio is constant in the atmosphere, and perhaps all you're describing is the atmospheric ratio, reflected in the cellulose samples you tested. So maybe all we can infer is that the world's average temperature doesn't vary very much, but then again that's kind of a tautology, isn't it?
Timothy, would be willing to provide a URL on your dept's website for us mere mortals to read the full article? I'm sure Nature won't mind, and we might get a better sense of whether what you say is true.
Don't be trendy! Step back for a moment, and think about how the art will look in ten years' time. This is how you will perceive several suggestions made here:
1. Fractal art: this was really big in the 80s and early 90s. 'Fess up. Doesn't it remind you of women with big hair in pink polyester jackets with wide shoulder pads?
2. M.C. Escher: this was also a fad a while ago, although you could argue it's got some staying power.
3. Procedurally-generated art, like the stuff made by Piet (below): this may also be "of a certain time".
4. Povray: the first ray-traced images contained lots of floating glassy spheres (it's easy to code), and looked cool. Now they look cheesy. I've seen lots of more complex povray scenes that I like, but I suspect that 10 years from now every video game will be able contain scenes like it, so the poster on the wall will seem a lot less remarkable.
5. Paintings about computers: someone here suggested commissioning an artist to paint an impression of computer science. This seems like a good idea, but remember that we computer people are snobs. Folks will always find something wrong with the work, some irritating thing that the artist (an outsider to our field) sees in CS, which we find incorrect or, at least, dated. It reminds me of a mural commissioned for the engineering building at my school, back in 1948. It's full of references to the threat of atomic war, and of the benign possibilities of atomic power. To me, it reeks of postwar angst.
So, what to do? What to do?
How about getting some real art up on that wall? You could commission an artist to paint something original, with no reference to CS in particular. Of course, art is subject to trends too, and the artist might give you something that future CS students, though they be non-artists, would sense belonged to a certain decade. Not to mention artists charge real money for real work.
Better to get something that everybody already knows is old but which most people like. Maybe some reproductions of Michelangelo's Sistine chapel, or some Renoir or Van Gogh. Something that has lasted a long time, because it speaks of some idea that is eternal, like religion, nature, human development (all those things that sound like cliches once you write them down). I personally like images by Annigoni: he's a 20th-century realist painter, many of whose images convey a sense of mystery. But that's my taste, and may not be in fashion ten years from now.
I stand corrected. Printing is cheap. So then, why do printed books cost so much? Why does an object that costs $5 to print end up costing $20 at the bookstore? Is it
Entrenched distributors who prey on publishers and bookstores alike? In other words, too many middlemen? Or,
Society? It's hard to be paid for creative work. Most of the public doesn't care for the work of writers. People can't help but write, and yet there are very few readers. As a result, almost all printed works have tiny audiences. What do you do if you are creative person who needs to express himself, but can't reach an audience?
I stand by my earlier statement that most books in stores go unsold. Perhaps this is the reason books end up costing so much. If you're going to all the trouble of publishing, paying authors and editors and distributors and sellers, but will only sell a few items, then each item will be very expensive.
It's kind of like art: few people buy art, few artists get paid, and most art costs a lot of money.
The reason paper books are so expensive is the HUGE overhead. First, the book must be written and edited (this overhead is unavoidable). But then, the book must be typeset, and the offset printing plates burned. This is very expensive, and is the reason why books with a print run of less than, say, five thousand copies are not economical to produce. Only if you have a captive audience (like students who MUST buy a textbook) can you charge enough to cover the cost of a smaller print run. Besides, the bookstores have a draconian system: they work on consignment, and are not required to actually pay the publisher until they sell the book to a customer. Any books not sold are returned to the publisher. These returns are almost always damaged, and cannot be sold through regular stores. They are either destroyed ("pulped"), or sold as remainders. The whole process is INCREDIBLY inefficient. It makes it very hard to publish a print book with a small niche audience.
Mine's in the basement, and I haven't used it in years. I had a great time with it back in the 80s. Used it as a terminal to log in to local BBSs (remember those?), bought a floppy drive for it, and then bought a third-party software upgrade which improved the UI and the floppy access. I managed to write an assembler for it (it ran an 8085C, I think), and I spent days poring through the ROM, finding interesting functions, until I realized there was a hardware manual available.
Lovely machine! The nicest keyboard feel on ANY machine, EVER! The Dell QuietKey I'm typing on now is clunky, loud, and stiff. The Model 100's keyboard is whisper quiet.
Your comments on beta-oxidation are confusing. Can you fill us in a bit more?
Personally, I find the idea of a low-carb diet for cancer makes some sense. After all, if cancer cells consume glucose at a prodigious rate, then bringing down the level of glucose in the bloodstream would be a good idea. I do know that lowcarb diets do indeed keep blood glucose levels constant.
Of course, this is "common sense", and the body doesn't always follow common sense. For example, exercise doesn't lead to weight loss, eating fat doesn't make you fat, etc.
One test for the low-carb-slows-cancer hypothesis would be if the growth rate of cancer were higher in people with high blood sugars. Do untreated diabetics tend to die of cancer faster?
While we're on the subject, there's an interesting book that touches on this subject: "Adam's Curse: A Future Without Men" by Bryan Sykes. I haven't read it yet (I'm male and it sounds depressing), but I've heard some interesting factoids contained within.
These include the fact that the Y chromosome is rather fragile (it has no counterpart from the female side, so it doesn't get enough genetic variability to evolve and get bad genes weeded out).
Another is that some species (eg the Komodo dragon) can, in some situations, use parthenogenesis (just like the Virgin Mary, or the Greek Gaia, or other godesses) to bear children without using sperm: the offspring, I think, are clones of the mother. There are several species that do this, but from an evolutionary standpoint, the strategy is flawed, because it doesn't introduce genetic variability.
Genetic variability is the key. Without it, a species can't adapt to changes in the environment, or to changes in disease organisms (who are always changing, to their advantage and our detriment). If there was no need for genetic variation, we could be immortal, and our species would need no further change, barring auto accidents and the like. That's why death exists: if we don't die, we don't make room for our slightly-different offspring, who we hope will resist environmental and microbial changes that we are vulnerable to. Death isn't caused by the body "wearing out". It's got a built-in clock. Else, statistics tells us that the bell curve of lifespan would have a very small but potentially infinite tail of very-long-lived individuals.
Modern agriculture is rife with examples of how lack of genetic variability causes trouble. Consider apples (which are all from grafts, because if you plant apple seeds, the resulting trees produce predominantly sour fruit): a few specimens were found to produce sweet, edible apples, and have been propagated by grafting onto sturdy root stock (so much for "Johnny Appleseed" who was actually planting trees for alcoholic cider, but that's another topic). The resulting trees require huge quantities of insecticides, fungicides, etc, because theyare very prone to insect and microbial diseases , which have changed since the time the original tree was found, while the latter tree has remained the same cloned specimen. Another example are bananas (also all grafted clones), which are being overtaken by a fungal disease, I think.
But I'm getting off topic. I presume the synthetic sperm in TFA would ideally come from a different woman, not from the mother's own marrow.
But hey, it's fascinating and scary, if you're a man. My biggest fear is that, after all those thousands of years it took us men to claw our way to the top of the gender ladder, we may have to give it all up.
You say that because sugar is natural, it's ok to eat. I see two problems with your argument.
First, just because sugar is "natural" doesn't mean it's good for you! Botulin is natural too. Corn has some fructose (hence it tastes sweet), so fructose is natural too. Many fruits have fructose too.
Second, I would argue that sugar is not really natural. Table sugar doesn't occur in nature: it's concentrated from sugar cane. Similarly high-fructose corn syrup doesn't occur in nature either: it's broken out of corn starches.
And third (yes, I promised only two problems, sorry), eating starchy food like spaghetti, potatoes and bread will send your blood glucose flying just as easily as driking HFCS-laden drinks.
And fourth, the American Diabetes Association is very much anti-lowcarb, and continues to push its "eat sugars and starches, and take your glucophage" phrma-financed agenda.
Your eye transfers raw data to your brain similar to a bitmap/RAW file. Sorry to nitpick, but actually your retina does a fair amount of preprocessing before signals are sent to the brain. Your retina has about 100 million rods and cones (pixels), but the optic nerve has about 1 million fibers. So a fair amount of processing has already happened before your brain "sees" anything. I'm pretty sure that edge detection, motion sensing, and lots of things like that have been applied to the data long before the brain gets it.
You bring up an interesting can of worms. It has to do with "hard AI".
Yes, the definition of "obvious" isn't obvious. If you could somehow define "obvious", then you could define "common sense", "truth", "good", "moral", and all sorts of important concepts. However, at some level, you have to abandon the hope of codifying these important concepts, because you are bound to hit brick walls. If you could codify "thought", then artificial intelligence would have succeeded long ago. Most people would agree that the initial lofty goals of AI (eg. passing the Turing test) are unachievable.
I think that laws suffer from this problem too. They are not defined mathematically, and besides they're not code; a computer isn't used to apply the law. Instead, human experts in the interpretation of law (lawyers and judges) must do the job. You will always need "wetware" if you have laws. People are just too creative and too variable for a single set of laws to suffice in all cases.
In the end, what really counts is good will. Without it, and without a sense of "fair play" (there's those pesky vague but important words again), the legal system doesn't work. That's my impression of what the supreme court was saying in this decision.
David Patterson has some very good advice on how to give a bad presentation. It assumes low tech (in 1983 all we had were transparent slides), but the spirit of the advice is what counts.
* If I go out and do 1000 KCal of exercise, I've increased my TEE by 1000 KCal.
* Try cutting 1000 KCal out of your diet. That's pretty hard unless you eat total junk.
I'm glad you bring up this argument. Let's look at it more carefully.
How much, exactly, is 1000 kilocalories? Suppose you lift a 50-pound weight 3 feet. Roughly, the amount of work needed is
E = mass * gravity * height = 25 kg * 10 m/s^2 * 1 m = 250 kg*m^2/s^2 = 250 Joules
Since a kilocalorie is 4184 Joules, this motion uses up 250/4184 = 0.06 Kcal, roughly. Thus, to do 1000 Kcal of mechanical work, you would need to lift the 50-pound weight 1000/0.06 = 16 thousand times!
I know that sounds ludicrous. So, let's acknowledge that human motion isn't efficient (I've read that it's 1% efficient, but I read that on the web, so maybe it wasn't true). At 1% efficiency, you just need to lift the weight 160 times. That's A LOT!
Let's do it again. I just found an article "Energy cost of treadmill running in non-trained females differing in body fat" which states that a person weight M kilos, walking L meters uses E = C*M*L Joules, where C is approximately 4 (google the article title to verify). Thus, if a person who weighs 75 kilos wants to use up 1000 kilocalories, or equivalently 4184000 Joules, they must walk
The moral of the story is this: exercise uses VERY FEW KILOCALORIES! If you want to substantially lose weight, you need to raise you basal metabolism. "Just sitting there" uses up 90% of most people's calories, whether they are totally sedentary, or moderately active. If you want to burn calories through exercise, you are going to be VERY busy, and rather tired.
Me, I get rather tired of people who advocate exercise as a way to lose weight. Maybe I should say I get rather exercised over it;-)
Slashdot Mirror
Once you've got the PDF, go to page 7 of the document (page 1087 in the printed journal). Right hand column, second paragraph reads:
It is reasonable to assume that persons with relatively high daily energy expenditures would be less likely to gain weight over time, compared with those who have low energy expenditures. So far, data to support this hypothesis are not particularly compelling ...
In other words, there are no good scientific studies that prove that exercise leads to weight loss.
Of course, exercise is good for you. But it won't help you lose weight.
So there. The big authorities (who surprisingly enough show scientific integrity) have said it.
Are you sure about this? Of course, it "makes sense", just like it makes sense that calorie restriction leads to weight loss. And yes, it has been said many times, so it must be true too.
To counter this assertion, I recommend a cool article by Gary Taubes (a scrupulous science writer with a low-carb bent) in "New York" magazine. In it, he presents evidence that exercise per se doesn't lead to weight loss.
What he does say, which I find interesting, is that people are born with a certain level of activity built in. Some people are nervous rabbit-like types like me, and they never gain weight (I eat lots, and exercise little). Other people are calm and sedentary, and tend to gain weight. What he points out is that thin people are prone to be active, whereas fat people are prone to inactivity. This is an observed correlation.
At this point, we will often jump to infer a causal effect from the correlation: we will conclude that it proves that exercise leads to weight loss. This inference is especially tempting because it meshes with the energy-balance theory of weight loss.
But Taubes cites a very thorough review of exercise-weight studies, in which the Finnish authors decided the problem was "more complex" than people think. People who exercised sometimes lost weight, sometimes gained. The cause-and-effect connection isn't really there.
The only rational explanation I can see is that metabolism adjusts to match caloric intake. The body is doing everything it can to keep body mass constant.
Looking at your post, I see that you are making several arguments in one:
Physics isn't being violated, thank god. The law of energy conservation still holds. But using a physics argument fails in this case, because the body is so adaptable. Metabolism must be adjusting to the calories being consumed. It must be going up when you eat more, and going down when you eat less. It's the only answer that fits the observed facts.
This doesn't make any sense, if you think about it. Yes, I know we've had that idea pounded into our brains for decades, but we're all techies here, and we should be able to do some math:
The amazing fact is that people's weight stays constant despite varying levels of calorie intake and exercise. The body is smart. It has had billions of years of evolution to build in mechanisms that help preserve the body in a constant form. Yes, it's true that if eat nothing you will eventually overcome those mechanisms, and lose weight, but that's not permanent. If you go back to eating normally, you will regain the weight.
There's so much morality-driven nonsense being promulgated about the virtues of exercise and caloric deprivation. But it's really just dogma that stands in the way of scientific reasoning.
Here's a simple bit of logic: a slice of bread (a mere trifle, you'll agree) has about 100 calories. Suppose your body burns X calories per day (say X=2500), and you accidentally eat one slice of bread too many. Over a year, you'll have eaten 36,500 too many calories, and since fat (body fat and also dietary fat) has 8 calories per gram, you'll have gained 36,000/8=4560 grams (about 10 pounds for you metric-deprived 'murricans).
Over 10 years, you'll gain 100 pounds! If, on the other hand, you erroneously omit that slice of bread, you'll become anorexic and probably die.
But this doesn't happen in practice! In practice, people don't hit their exact metabolic requirements every day. It's hit and miss. And yet the very well established medical fact is that most people retain the same constant weight despite a completely varying dietary intake.
Well, you'll argue that on average you'll hit the target, but why should that be so? Yes, there are people who tend to gain weight, but the vast majority of people keep their weight constant, even though their average dietary intake probably doesn't match their metabolic "ideal" exactly.
The answer is that you metabolism adjusts to match your caloric intake. Your body is way smarter than you when it comes to weight. It's gonna do its best to keep weight constant no matter how hard you try.
Go on, tell me I'm full of sh*t. But use reason. Don't spout preconceived dogma.
In a car, the number of Joules expended is exactly matched by the Joules taken in as gasoline. But how can you account for the fact that most people's weight remains constant despite wildly varying daily caloric intake? Doesn't that tell you that people aren't like cars?
Wake up and smell the morality-driven bad medical advice that's been promulgated for the past fifty years.
Jeez.
Consider calorie restriction. Suppose your base metabolism is such that you burn 2000 calories per day. Let's hypothesize the (apparently obvious) premise that any calories ingested beyond this value will be stored as fat (and conversely, if you eat less than 2000, you'll burn fat).
Well, how the heck do you manage to eat exactly 2000 calories per day? It's very hard. Suppose you're off by 100 calories, which is not hard to do (eg, a slice of white bread has 80 calories). You consistently eat 100 calories too many, every day. Well, after 365 days, you'll have eaten 36,500 calories too many, and since one gram of fat has 8 calories, you'll have gained 4.5 kilos, or about 10 pounds. Keep this up for 10 years, and you'll have gained 100 pounds. Amazing!
Conversely, if you consistently eat one slice of bread too few, you'll lose 100 pounds in 10 years, and die of anorexia!
Silly, isn't it? Let's make it more random, and assume that some days you eat 100 calories too many, some days 100 too few, at random. There is a substantial probability that the surplus and the deficit will not cancel out exactly. After all, the odds of tossing a coin 365 times and have it come up HTHTHTHTHTHTHTHTHTHT... heads and tails alternating exactly, cancelling each other out, is 0.5^365, which is a very small number (about 10^-110). ANY OTHER OUTCOME LEADS TO WEIGHT LOSS OR GAIN!
So, you'd expect to see people walking around weighing thousands of pounds, or being skeletons and dying in droves.
But this doesn't happen. The observed fact is that most people hold the SAME weight for many years. The body follows a "set point".
So, something else must cause weight gain. It's certainly not calories.
Followup: I checked the senatorial results myself, and the Democrat (Max Cleland) won both in both Dekalb and Fulton counties.
Hear hear! For god's sake people, don't just go off half-cocked when you read an article. Go check the data! I've managed with little effort to pull up the county-by-county results for the 2002 Georgia gubernatorial election.
Look here for election results.
Look here for a map where the counties are labeled.
You'll notice the following: In Fulton county, the Democrat candidate won 62% to 35%. In Dekalb county, he won 74% to 24%.
I'll leave it to some other person to look up the senatorial election results. The results I've found suggest the following explanations:
Either the patches failed to achieve the desired
One comment also says that people have actually measured leaf temperatures directly (using thermometers, of all things): leaves can get very hot, and very cold, and that they don't usually keep a constant avg temp.
Another comment states that out that you're using ratios of oxygen isotopes to infer the average temperature. This ratio is constant in the atmosphere, and perhaps all you're describing is the atmospheric ratio, reflected in the cellulose samples you tested. So maybe all we can infer is that the world's average temperature doesn't vary very much, but then again that's kind of a tautology, isn't it?
Timothy, would be willing to provide a URL on your dept's website for us mere mortals to read the full article? I'm sure Nature won't mind, and we might get a better sense of whether what you say is true.
1. Fractal art: this was really big in the 80s and early 90s. 'Fess up. Doesn't it remind you of women with big hair in pink polyester jackets with wide shoulder pads?
2. M.C. Escher: this was also a fad a while ago, although you could argue it's got some staying power.
3. Procedurally-generated art, like the stuff made by Piet (below): this may also be "of a certain time".
4. Povray: the first ray-traced images contained lots of floating glassy spheres (it's easy to code), and looked cool. Now they look cheesy. I've seen lots of more complex povray scenes that I like, but I suspect that 10 years from now every video game will be able contain scenes like it, so the poster on the wall will seem a lot less remarkable.
5. Paintings about computers: someone here suggested commissioning an artist to paint an impression of computer science. This seems like a good idea, but remember that we computer people are snobs. Folks will always find something wrong with the work, some irritating thing that the artist (an outsider to our field) sees in CS, which we find incorrect or, at least, dated. It reminds me of a mural commissioned for the engineering building at my school, back in 1948. It's full of references to the threat of atomic war, and of the benign possibilities of atomic power. To me, it reeks of postwar angst.
So, what to do? What to do?
How about getting some real art up on that wall? You could commission an artist to paint something original, with no reference to CS in particular. Of course, art is subject to trends too, and the artist might give you something that future CS students, though they be non-artists, would sense belonged to a certain decade. Not to mention artists charge real money for real work.
Better to get something that everybody already knows is old but which most people like. Maybe some reproductions of Michelangelo's Sistine chapel, or some Renoir or Van Gogh. Something that has lasted a long time, because it speaks of some idea that is eternal, like religion, nature, human development (all those things that sound like cliches once you write them down). I personally like images by Annigoni: he's a 20th-century realist painter, many of whose images convey a sense of mystery. But that's my taste, and may not be in fashion ten years from now.
- Entrenched distributors who prey on publishers and bookstores alike? In other words, too many middlemen? Or,
- Society? It's hard to be paid for creative work. Most of the public doesn't care for the work of writers. People can't help but write, and yet there are very few readers. As a result, almost all printed works have tiny audiences. What do you do if you are creative person who needs to express himself, but can't reach an audience?
It's kind of like art: few people buy art, few artists get paid, and most art costs a lot of money.I stand by my earlier statement that most books in stores go unsold. Perhaps this is the reason books end up costing so much. If you're going to all the trouble of publishing, paying authors and editors and distributors and sellers, but will only sell a few items, then each item will be very expensive.
The reason paper books are so expensive is the HUGE overhead. First, the book must be written and edited (this overhead is unavoidable). But then, the book must be typeset, and the offset printing plates burned. This is very expensive, and is the reason why books with a print run of less than, say, five thousand copies are not economical to produce. Only if you have a captive audience (like students who MUST buy a textbook) can you charge enough to cover the cost of a smaller print run. Besides, the bookstores have a draconian system: they work on consignment, and are not required to actually pay the publisher until they sell the book to a customer. Any books not sold are returned to the publisher. These returns are almost always damaged, and cannot be sold through regular stores. They are either destroyed ("pulped"), or sold as remainders. The whole process is INCREDIBLY inefficient. It makes it very hard to publish a print book with a small niche audience.
Lovely machine! The nicest keyboard feel on ANY machine, EVER! The Dell QuietKey I'm typing on now is clunky, loud, and stiff. The Model 100's keyboard is whisper quiet.
I'm getting all teary-eyed.
Your comments on beta-oxidation are confusing. Can you fill us in a bit more?
Personally, I find the idea of a low-carb diet for cancer makes some sense. After all, if cancer cells consume glucose at a prodigious rate, then bringing down the level of glucose in the bloodstream would be a good idea. I do know that lowcarb diets do indeed keep blood glucose levels constant.
Of course, this is "common sense", and the body doesn't always follow common sense. For example, exercise doesn't lead to weight loss, eating fat doesn't make you fat, etc.
One test for the low-carb-slows-cancer hypothesis would be if the growth rate of cancer were higher in people with high blood sugars. Do untreated diabetics tend to die of cancer faster?
While we're on the subject, there's an interesting book that touches on this subject: "Adam's Curse: A Future Without Men" by Bryan Sykes. I haven't read it yet (I'm male and it sounds depressing), but I've heard some interesting factoids contained within.
These include the fact that the Y chromosome is rather fragile (it has no counterpart from the female side, so it doesn't get enough genetic variability to evolve and get bad genes weeded out).
Another is that some species (eg the Komodo dragon) can, in some situations, use parthenogenesis (just like the Virgin Mary, or the Greek Gaia, or other godesses) to bear children without using sperm: the offspring, I think, are clones of the mother. There are several species that do this, but from an evolutionary standpoint, the strategy is flawed, because it doesn't introduce genetic variability.
Genetic variability is the key. Without it, a species can't adapt to changes in the environment, or to changes in disease organisms (who are always changing, to their advantage and our detriment). If there was no need for genetic variation, we could be immortal, and our species would need no further change, barring auto accidents and the like. That's why death exists: if we don't die, we don't make room for our slightly-different offspring, who we hope will resist environmental and microbial changes that we are vulnerable to. Death isn't caused by the body "wearing out". It's got a built-in clock. Else, statistics tells us that the bell curve of lifespan would have a very small but potentially infinite tail of very-long-lived individuals.
Modern agriculture is rife with examples of how lack of genetic variability causes trouble. Consider apples (which are all from grafts, because if you plant apple seeds, the resulting trees produce predominantly sour fruit): a few specimens were found to produce sweet, edible apples, and have been propagated by grafting onto sturdy root stock (so much for "Johnny Appleseed" who was actually planting trees for alcoholic cider, but that's another topic). The resulting trees require huge quantities of insecticides, fungicides, etc, because theyare very prone to insect and microbial diseases , which have changed since the time the original tree was found, while the latter tree has remained the same cloned specimen. Another example are bananas (also all grafted clones), which are being overtaken by a fungal disease, I think.
But I'm getting off topic. I presume the synthetic sperm in TFA would ideally come from a different woman, not from the mother's own marrow.
But hey, it's fascinating and scary, if you're a man. My biggest fear is that, after all those thousands of years it took us men to claw our way to the top of the gender ladder, we may have to give it all up.
You say that because sugar is natural, it's ok to eat. I see two problems with your argument.
First, just because sugar is "natural" doesn't mean it's good for you! Botulin is natural too. Corn has some fructose (hence it tastes sweet), so fructose is natural too. Many fruits have fructose too.
Second, I would argue that sugar is not really natural. Table sugar doesn't occur in nature: it's concentrated from sugar cane. Similarly high-fructose corn syrup doesn't occur in nature either: it's broken out of corn starches.
And third (yes, I promised only two problems, sorry), eating starchy food like spaghetti, potatoes and bread will send your blood glucose flying just as easily as driking HFCS-laden drinks.
And fourth, the American Diabetes Association is very much anti-lowcarb, and continues to push its "eat sugars and starches, and take your glucophage" phrma-financed agenda.
You bring up an interesting can of worms. It has to do with "hard AI".
Yes, the definition of "obvious" isn't obvious. If you could somehow define "obvious", then you could define "common sense", "truth", "good", "moral", and all sorts of important concepts. However, at some level, you have to abandon the hope of codifying these important concepts, because you are bound to hit brick walls. If you could codify "thought", then artificial intelligence would have succeeded long ago. Most people would agree that the initial lofty goals of AI (eg. passing the Turing test) are unachievable.
I think that laws suffer from this problem too. They are not defined mathematically, and besides they're not code; a computer isn't used to apply the law. Instead, human experts in the interpretation of law (lawyers and judges) must do the job. You will always need "wetware" if you have laws. People are just too creative and too variable for a single set of laws to suffice in all cases.
In the end, what really counts is good will. Without it, and without a sense of "fair play" (there's those pesky vague but important words again), the legal system doesn't work. That's my impression of what the supreme court was saying in this decision.
David Patterson has some very good advice on how to give a bad presentation. It assumes low tech (in 1983 all we had were transparent slides), but the spirit of the advice is what counts.
o n.htm
http://www.presentationhelper.co.uk/badpresentati
* If I go out and do 1000 KCal of exercise, I've increased my TEE by 1000 KCal.
;-)
* Try cutting 1000 KCal out of your diet. That's pretty hard unless you eat total junk.
I'm glad you bring up this argument. Let's look at it more carefully.
How much, exactly, is 1000 kilocalories? Suppose you lift a 50-pound weight 3 feet. Roughly, the amount of work needed is
E = mass * gravity * height = 25 kg * 10 m/s^2 * 1 m = 250 kg*m^2/s^2 = 250 Joules
Since a kilocalorie is 4184 Joules, this motion uses up 250/4184 = 0.06 Kcal, roughly. Thus, to do 1000 Kcal of mechanical work, you would need to lift the 50-pound weight 1000/0.06 = 16 thousand times!
I know that sounds ludicrous. So, let's acknowledge that human motion isn't efficient (I've read that it's 1% efficient, but I read that on the web, so maybe it wasn't true). At 1% efficiency, you just need to lift the weight 160 times. That's A LOT!
Let's do it again. I just found an article "Energy cost of treadmill running in non-trained females differing in body fat" which states that a person weight M kilos, walking L meters uses E = C*M*L Joules, where C is approximately 4 (google the article title to verify). Thus, if a person who weighs 75 kilos wants to use up 1000 kilocalories, or equivalently 4184000 Joules, they must walk
L = 4184000 Joules / (4 * 75) = 14000 meters = 14 kilometers = 8.5 miles.
That's A LOT!
The moral of the story is this: exercise uses VERY FEW KILOCALORIES! If you want to substantially lose weight, you need to raise you basal metabolism. "Just sitting there" uses up 90% of most people's calories, whether they are totally sedentary, or moderately active. If you want to burn calories through exercise, you are going to be VERY busy, and rather tired.
Me, I get rather tired of people who advocate exercise as a way to lose weight. Maybe I should say I get rather exercised over it