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How do we know how hot the sun is?

Posted date: 9:40 PM / comment : 0 ,


That's a great question that took surprisingly long into the history of physics to figure out! I'll skip the historical details (although you should read about it here) and cut to the chase: It turns out that everything with a non-zero temperature emits light all the time. This isn't necessarily the type of light that your eyes can detect, but it's there all the same. It was discovered experimentally long before it was explained theoretically (it took until the year 1900), but now we have a pretty good understanding of what's happening inside things when they glow. In fact, it's the same reason that a hot object in a fire will begin to glow red, and why fire itself is orange at the top.
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This radiation is called Blackbody Radiation, named so because the form of the radiation is derived by assuming that the body is completely black, i.e., it absorbs all incoming light and doesn't scatter or reflect any. The only light that is emitted is actually generated inside the object, not just reflected from a nearby flashlight. The useful thing about blackbody radiation is that the spectrum of light that's emitted is determined by the temperature and nothing else. That means that we can measure the spectrum of emitted blackbody radiation from an object and immediately know its temperature.
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There are some caveats though; some materials don't play by the rules, instead choosing to emit light that's not well-described by the blackbody radiation spectrum. Luckily for us, the sun is one of the most ideal blackbody radiators that we've discovered: that means our estimate of the temperature (on the surface anyway) is really quite accurate.

DNA and How to Extract It

Posted date: 6:17 PM / comment : 0 ,

DNA and How to Extract It

This past March, a few days after my birthday, I spent a Saturday teaching three iterations of a three-hour-long class called Hands-on Introduction to DNA! to seventh through ninth graders at Spark, a day-long assortment of classes for middle and high school students organized by the MIT student group ESP (Educational Studies Program) and taught by MIT students and community members. ESP seems to contain most of my Random Hall friends as well as the wonderful Anna H. ’14, who has blogged about teaching ESP classes here and here.
This year’s 266 Spark classes included classes you might expect, such as Computational Language Theory and Extreme Math, and classes you might not expect, such as How to Plan and Execute Covert Operations in Deep Cover and The Game Mechanics of Pokémon. There was Synthetic Biology, Projective Geometry, Chocolate Tasting, and Slide Rules. There was Crayfish: Take It Apart!, Sea Urchin: Take It Apart!, and their antithesis, Put Together the Pile of Junk!
My Spark class revolved around a DNA extraction protocol that my little brother Max tried as a science fair project. We started out with a short introductory lecture about DNA and then we isolated the genetic material from peas, corn, and strawberries, which was an awesome, colorful, goopy mess. If DNA is nothing new, feel free to skip to the video and the extraction protocol, or just the extraction protocol.
From the beginning—
Our bodies are an ecosystem of hundreds of trillions of tiny bacteria and tens of trillions of our own cells, small bags of stuff that do a lot of work to keep us alive. We are interested in the nucleus of the cell, which encloses the DNA.
Your DNA is a story, uniquely yours, that you read out as you live and eventually pass on to your children. Instead of paper, it is written on a long string using only four letters. Each word in the story is three letters long. The words form sentences called genes, which, alone or in groups, determine the traits you start with, for example your hair color, your eye color, and your blood type. Though your cells have diverse specializations, your DNA is identical in every cell of your body. It contains all the information needed to build you up and then maintain you; it determines how you will grow and develop within your environment and to a potentially large extent it dictates how and when you will eventually break apart and die.
A priority in current research is deciphering our DNA and the DNA of other species for use in medicine, agriculture, and history. The hope is that by learning how to read our DNA, we will be able to better understand genetic disordersand detect them before they appear, improve crop yield, and understand how we got to be human. Genomics is a new and quickly evolving field with a huge capacity to extend and improve human life.
For the most part, DNA carries out its action through proteins. A gene is first transcribed into less stable messenger RNA. Interrupting, or intronic, information is cut out of the messenger RNA and the remaining RNA molecule is sent out of the nucleus and into the endoplasmic reticulum. In the endoplasmic reticulum the messenger RNA is copied again, this time into protein. This final translation is done by transfer molecules, which contain the code for translation, and ribosomes, which line up the messenger RNA and the transfer molecules so that they can interact. The transfer molecules, called tRNAs, are like three-pronged forks. On one end are three letters from the original DNA sequence, a word, written in RNA. The other end holds the corresponding protein monomer, the amino acid. The amino acid that corresponds to each word varies depending on the species. The ribosome lines up the transfer molecule forks with the attached protein monomers along the RNA. The amino acids are connected to form a protein, after which the transfer molecules are reused and the messenger RNA is degraded.
The cell sends the completed protein product to the Golgi apparatus, the cell’s post office, and the Golgi packages the protein and sends it to its destination inside or outside the cell. The protein then carries out the function prescribed by its encoding DNA, whether it is the keratin in your hair or an antibody in your immune system. Meanwhile the original DNA is safe in the nucleus, in two copies. It never leaves, and it is split apart and replicated only when the entire cell is replicated.
The human genome is written in about 3 billion base pairs, or letters. If you stretch out the DNA from one nonreplicating cell, it will be about two meters long (3 billion base pairs in 23 chromosomes ∙ two of each chromosome in the cell ∙ 0.34 nanometers between consecutive base pairs). If you concatenate the DNA from all of your cells and stretch it out as one string, it will reach the sun and back 67 to 333 times, or the moon and back 25,000 to 125,000 times (2 meters of DNA in each cell ∙ about 10 to 50 trillion cells in the human body ÷ 300 million kilometers from the Earth to the sun and back, or 800,000 kilometers from the Earth to the moon and back). In the cell, the DNA is wound tightly around proteins called histones, and for this reason, even though we will try to degrade the proteins, the DNA will precipitate in clumps rather than clean strings when we extract it from a vegetable or fruit.
Here’s all that in vivid, computer animated action:
This video is from the Walter and Eliza Hall Institute of Medical Research in Australia. They have other equally mesmerizing and informative animations in high definition on their web site, and you should go watch them, too, if you enjoyed this one.
While we watched this video we set up the first steps of the DNA extraction protocol, which contains a convenient 10-minute break. Below is the protocol we used. The students wanted to know what each step does to the DNA, so I’ll try to explain it here as well.

Materials:

  • A blender.
  • A mesh strainer with very small holes.
If you are alone:
  • A clear cup. It looks really cool if you use a champagne glass.
  • A wooden BBQ skewer or something else with which to stir.
  • One eighth teaspoon table salt.
  • About one cup of cold water.

     
  • A pinch of meat tenderizer or contact lens solution. (We used meat tenderizer.)
     
  • Two tablespoons liquid laundry detergent. Use clear laundry detergent. Colored laundry detergent will overpower the color of the fruit or vegetable.
  • About half a cup of something that was once alive. It’s okay if it’s frozen. We tried strawberries, split peas, and corn. The kids were most excited about the strawberries. I thought the peas looked coolest. The frozen corn was not very exciting for anybody.
  • A small jug of rubbing alcohol with at least 95% alcohol content.



If you are with 10-20 friends:
  • A bag of small, clear, disposable cups. The more translucent cups are worth the extra money.
  • A bag of wooden BBQ skewers or something else with which to stir.
  • One container of table salt from your kitchen.
  • Gallon jug of cold water, which you brought to school empty and filled with cold tap water in the bathroom before class.
  • Two small shakers of meat tenderizer. You won’t use much of this, but it’s better to have two so that they can both be passed around at the same time.
  • A small bottle of clear liquid laundry detergent.

     
  • A bag or two or three of something that was once alive, like a fruit or a vegetable. It’s okay if it’s frozen.


     
  • Several jugs of rubbing alcohol with about 95% alcohol content. You’ll need about as much rubbing alcohol as vegetable or fruit, which might be a lot. (Weird looks at the check-out line come with the vast, yellow and green polka-dotted territory of being awesome.) Leave time to potentially stop by multiple CVSes.
Among the materials, rubbing alcohol (isopropyl alcohol) can cause irritation to eyes, skin, or the respiratory system. Isopropyl alcohol vapors can irritate the eyes and the respiratory system, contact with eyes can cause damage and burns, and ingestion or inhalation can cause vomiting, drowsiness, and death. The lethal dose is about one cup. It’s unlikely you’ll be able to drink very much, but if you do you will die. You also don’t want to eat the laundry detergent or get it in your eyes.

Procedure:

  1. Combine in the blender one part vegetable or fruit, two parts cold water, and the salt. If you’re doing this alone, it’ll be half a cup of vegetable or fruit, one cup water, and one eighth teaspoon salt. If you’re doing this with a group you’ll want to fill the blender and scale up the salt appropriately. Blend on high for 15 to 25 seconds. It is not important that the water be cold, but it is helpful. Most things, including DNA, tend to be less soluble at lower temperatures. (The exception is proteins, which start denaturing, or losing their structure, at higher temperatures, exposing their hydrophobic parts and forcing them to clump together to avoid surrounding water.) The salt, NaCl, dissolves in the water, separating into the charged ions Na+ and Cl-. The Na+ neutralizes the negatively charged DNA, allowing the DNA strands to clump together rather than be repelled by each other’s negative charge.
  2. Balance your mesh strainer over a clear cup and pour the liquid contents of the blender through the strainer and into the cup. The cup should be at most half full. If you’re doing this with a group you should divide the contents of the blender equally among the group and line the cups up on the table for the next step. Keep in mind that the goop that comes out of the blender earlier has more DNA in it than the goop that comes out of the blender later.
  3. Add two tablespoons of clear liquid laundry detergent to each cup of vegetable goop. If you’re doing this with a group you can use the bottommost line in one of the plastic cups to measure out a very approximate two tablespoons. The laundry detergent disrupts the membrane enclosing the cell and potentially the nuclear membrane enclosing the DNA.
  4. Distribute a vegetable goop cup and a BBQ skewer to each person. Everyone should stir gently and then let the solution stand for 10 minutes. Now is a good time to watch the above 7-minute video.
  5. Pass around the meat tenderizer and the rubbing alcohol. Each person should add a pinch of meat tenderizer to their cup and stir gently again, and then add about as much rubbing alcohol as there is vegetable mixture. The rubbing alcohol makes the DNA clump together, since the DNA is less soluble in rubbing alcohol (or any other alcohol) than in water. The meat tenderizer contains protease, an enzyme that degrades the proteins that accompany the DNA.
The DNA will appear as white goop on the surface of the green or red goop. You can spin it onto the BBQ skewer like cotton candy, but I think it looks prettier and much less gross if it’s left in the cup. Here are some photos my students took at the end of the process. The fruits and vegetables used, clockwise from the top left, are strawberries, peas, corn, and mixed berry, all frozen. That no one photographed the DNA extracted from the corn is, I think, additional testament to frozen corn not being very interesting.
 

 
  

Afterwards, I opened the floor to questions and short chalk talks and we ended up going in very interesting directions. I almost wish I’d had an older class so that students could teach each other more than I talked at them, but at the same time it seems like younger people ask more questions and their questions are often more interesting. Some of the things we talked about were transposons, viruses, cancer, stem cells, ribosomes and the RNA world, DNA sequencing technologies, sex chromosomes and their evolution, alternative splice sites, and the evolutionary benefits of aging and death.
I got some emails in the following days expressing interest in biology and asking about things we talked about in class, which was such a wonderful feeling. If you have time and a presentation at your local elementary school seems like something you would enjoy, you should ask about trying it. A few weeks ago my mom repeated the presentation and the DNA extraction with my little brother’s fifth grade class, and apparently they asked even more interesting questions. It seems like elementary school teachers are usually thrilled to have alumni or parents present about what they've been up to in high school and college and beyond.
If you are in middle or high school and you'd like to learn more about genomics and DNA, there are free resources online that you should check out:
  • edx.org Free online courses from MIT, Harvard, and other excellent schools that mirror actual undergraduate courses, with labs, graded tests, online real-human interaction, and the possibility of earning a certificate. In particular, you might be interested in:
    • 7.00x Introduction to Biology: The Secret of Life, taught by Dr. Eric Lander, from the Human Genome Project
    • 6.00x Introduction to Computer Science and Programming
  • ocw.mit.edu Free material from many, many MIT classes, including video lectures. In particular, you might be interested in:
    • Biology highlights for high school
    • 7.01SC Fundamentals of Biology, also taught by Dr. Eric Lander, along with Dr. Robert Weinberg, who made huge contributions to cancer research (both won 3 million dollars this past February for their research)
    • 6.00SC Introduction to Computer Science and Programming
  • codecademy.com Free interactive programming classes online.
  • wikipedia.org/wiki/genomics Excellent introductory information. Follow the links!
If you have questions, if you do a presentation, or if you try a DNA extraction, alone or with a class, and you comment or email me about what happened it would make me very happy—especially if you are adventurous and try a DNA extraction from something new. )

No such thing as porn “addiction,” researchers say

Posted date: 9:47 AM / comment : 0 , , , ,

Review article highlights lack of strong research about addictive nature of viewing sexual images
Journalists and psychologists are quick to describe someone as being a porn “addict,” yet there’s no strong scientific research that shows such addictions actually exists. Slapping such labels onto the habit of frequently viewing images of a sexual nature only describes it as a form of pathology. These labels ignore the positive benefits it holds. So says David Ley, PhD, a clinical psychologist in practice in Albuquerque, NM, and Executive Director of New Mexico Solutions, a large behavioral health program. Dr. Ley is the author of a review article about the so-called “pornography addiction model,” which is published in Springer’s journal Current Sexual Health Reports.
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Current Sexual Health Reports
“Pornography addiction” was not included in the recently revised Diagnostic and Statistical Manual because of a lack of scientific data. Fewer than two in every five research articles (37 percent) about high frequency sexual behavior describe it as being an addiction. Only 27 percent (13 of 49) of articles on the subject contained actual data, while only one related psychophysiological study appeared in 2013. Ley’s review article highlights the poor experimental designs, methodological rigor and lack of model specification of most studies surrounding it.
The research actually found very little evidence – if any at all – to support some of the purported negative side effects of porn “addiction.” There was no sign that use of pornography is connected to erectile dysfunction, or that it causes any changes to the brains of users. Also, despite great furor over the effects of childhood exposure to pornography, the use of sexually explicit material explains very little of the variance in adolescents' behaviors. These are better explained and predicted by other individual and family variables.
Instead, Ley and his team believe that the positive benefits attached to viewing such images do not make it problematic de facto. It can improve attitudes towards sexuality, increase the quality of life and variety of sexual behaviors and increase pleasure in long-term relationships. It provides a legal outlet for illegal sexual behaviors or desires, and its consumption or availability has been associated with a decrease in sex offenses, especially child molestation.
Clinicians should be aware that people reporting “addiction” are likely to be male, have a non-heterosexual orientation, have a high libido, tend towards sensation seeking and have religious values that conflict with their sexual behavior and desires. They may be using visually stimulating images to cope with negative emotional states or decreased life satisfaction.
“We need better methods to help people who struggle with the high frequency use of visual sexual stimuli, without pathologizing them or their use thereof,” writes Ley, who is critical about the pseudoscientific yet lucrative practices surrounding the treatment of so-called porn addiction. “Rather than helping patients who may struggle to control viewing images of a sexual nature, the ‘porn addiction’ concept instead seems to feed an industry with secondary gain from the acceptance of the idea.”
Reference:
Ley, D. et al. (2014). The Emperor Has No Clothes: A Review of the “Pornography Addiction” Model, Current Sexual Health Reports. DOI 10.1007/s11930-014-0016-8.

Nanomotors are controlled, for the first time, inside living cells

Posted date: 12:52 PM / comment : 0 , ,

UNIVERSITY PARK, Pa. -- For the first time anywhere, a team of chemists and engineers at Penn State has placed tiny synthetic motors inside live human cells, propelled them with ultrasonic waves and steered them magnetically. It's not exactly "Fantastic Voyage," but it's close. The nanomotors, which are rocket-shaped metal particles, move around inside the cells, spinning and battering against the cell membrane.
Optical microscope image of a HeLa cell containing several gold-ruthenium nanomotors.
Nanomotors are controlled, for the first time, inside living cells
"As these nanomotors move around and bump into structures inside the cells, the live cells show internal mechanical responses that no one has seen before," said Tom Mallouk, Evan Pugh Professor of Materials Chemistry and Physics. "This research is a vivid demonstration that it may be possible to use synthetic nanomotors to study cell biology in new ways. We might be able to use nanomotors to treat cancer and other diseases by mechanically manipulating cells from the inside. Nanomotors could perform intracellular surgery and deliver drugs noninvasively to living tissues."
Up until now, Mallouk said, nanomotors have been studied only "in vitro" in a laboratory apparatus, not in living human cells. Chemically powered nanomotors were first developed 10 years ago at Penn State by a team that included chemist Ayusman Sen and physicist Vincent Crespi, in addition to Mallouk.

Very active gold nanorods internalized inside HeLa cells in an acoustic field

A demonstration of very active gold nanorods internalized inside HeLa cells in an acoustic field. This video was taken under 1000X magnification in the bright field, with most of the incoming light blocked at the aperture.
Mallouk Lab, Penn State

"Our first-generation motors required toxic fuels and they would not move in biological fluid, so we couldn't study them in human cells," Mallouk said. "That limitation was a serious problem." When Mallouk and French physicist Mauricio Hoyos discovered that nanomotors could be powered by ultrasonic waves, the door was open to studying the motors in living systems.
For their experiments, the researchers use HeLa cells, an immortal line of human cervical cancer cells that typically is used in research studies. These cells ingest the nanomotors, which then move around within the cell tissue, powered by ultrasonic waves. At low ultrasonic power, Mallouk explained, the nanomotors have little effect on the cells. But when the power is increased, the nanomotors spring into action, moving around and bumping into organelles -- structures within a cell that perform specific functions. The nanomotors can act as egg beaters to homogenize the cell's contents, or they can act as battering rams to puncture the cell membrane.\


The assembly of a rotating HeLa cell/gold rod aggregate at an acoustic nodal line in xy plane.

The assembly of a rotating HeLa cell/gold rod aggregate at an acoustic nodal line in the xy plane. The video was taken under 500X overall magnification except for 00:23 - 00:32 and 01:16 - 01:42, where a 200X overall magnification was used. 
Mallouk Lab, Penn State

While ultrasound pulses control whether the nanomotors spin around or whether they move forward, the researchers can control the motors even further by steering them, using magnetic forces. Mallouk and his colleagues also found that the nanomotors can move autonomously -- independently of one another -- an ability that is important for future applications.
"Autonomous motion might help nanomotors selectively destroy the cells that engulf them," Mallouk said. "If you want these motors to seek out and destroy cancer cells, for example, it's better to have them move independently. You don't want a whole mass of them going in one direction."
The ability of nanomotors to affect living cells holds promise for medicine, Mallouk noted.
"One dream application of ours is Fantastic Voyage-style medicine, where nanomotors would cruise around inside the body, communicating with each other and performing various kinds of diagnoses and therapy. There are lots of applications for controlling particles on this small scale, and understanding how it works is what's driving us."
The researchers' findings were published in Angewandte Chemie International Edition on Feb. 10. In addition to Mallouk, co-authors include Penn State researchers Wei Wang, Sixing Li, Suzanne Ahmed, and Tony Jun Huang, as well as Lamar Mair of Weinberg Medical Physics in Maryland. The research was funded by the National Science Foundation (MRSECgrant DMR-0820404), the National Institutes of Health, the Huck Innovative and Transformative Seed Fund (HITS) and Penn State.

Married Men Are Fatter Than Their Singleton Counterparts

Posted date: 10:47 AM / comment : 0 , , ,

It's an old wives tale that women "let themselves go" after marriage, a new study suggests. It's actually married men who are larger than their single counterparts. 
man and woman walking couple hand in hand
Many studies point to the health and psychological benefits of marriage, but the new study published in the journal Families, Systems, & Health on Jan. 13 suggests that marriage may not be as great as it seems health-wise — at least not for men.
The scientists used data from Project EAT that monitored the diet, physical activity, and weight status of about 2,300 young adults in the Midwest. About 35% of the total sample were single or casually dating, 42% were in a committed relationship, and 23% were married.
The results suggest that married men were 25% more likely to be overweight or obese than single men or men in committed relationship. The scientists defined overweight as people having a body mass index over 25.
In the image below the first column of numbers shows the percent of men who are overweight and the last column shows the percent of women who are overweight. You can see that the married men column have the highest rate of obesity at 58.5%.
relationships and health

One of the most surprising results from the study is that married women were much more likely to regularly eat breakfast. They were 47% more likely to eat breakfast at least five times per week than single women or women in a committed relationship.
In the image below the first column of numbers shows the percent of men who eat breakfast and the last column of numbers shows the percent of women who eat breakfast at least five times per week. More than 60% of married eat breakfast regularly. 
relationship and health
There are tons of health benefits that come from eating breakfast, so the results of the study suggest that some married women may have a healthy edge.
This does not mean that being married will suddenly make you fat if you're a man, or make you crave breakfast if you're a woman. There are many other factors at play beyond the scope of the study, including who is likely to get married in the first place, the duration of relationships, and the tendency for people to select a partner based on shared habits.
The scientists found that relationship status made little difference in other health behaviors like eating lots of fruits and vegetables, eating less fast food, and exercising. Next they hope to examine how the quality of the relationship affects the health behaviors of the couple.

Smoke Ban in Public Places Helps Smokers Quit, Study Says

Posted date: 12:22 PM / comment : 0 , ,

The war many organizations and public health care officials have been waging against cigarettes haven't been fruitless.
Youth smokers
  • (Photo : Reuters) Most U.S. youth exposed to tobacco advertising in stores
According to a study by the University of California San Diego, measures like baning smoking in public places and work actually help smokers cut back or entirely quit.
"When there's a total smoking ban in the home, we found that smokers are more likely to reduce tobacco consumption and attempt to quit than when they're allowed to smoke in some parts of the house," said Wael K. Al-Delaimy, MD, PhD, professor and chief of the Division of Global Health in the UC San Diego Department of Family and Preventive Medicine in apress statement. "The same held true when smokers report a total smoking ban in their city or town. Having both home and city bans on smoking appears to be even more effective."
An estimated 43.8 million people or 19 percent of all adults in the United States smoke cigarettes. Smoking is the leading cause of preventable deaths in the United States accounting for more than 440,000 deaths or one in every five deaths in the country each year.
For the study researchers surveyed 1,718 smokers in the state of California. They found that total smoking bans in homes was more effective in reducing smoking and successful quitting than partial bans. Researchers found that smokers were more likely to successfully quite smoking in states where bans were implemented than states where bans were not.
Another observation made in the study was that home smoking bans were more effective in reducing cigarette consumption among females and people above 65 years of age while total state bans were more effective in male smokers quitting.
In 1994, California became the first state to ban smoking and received a very positive response. The benefits of this ban were evident and prevented non-smokers from being affected by second-hand smoking. A previous study found that second-hand smoking, commonly known as passive smoking is more harmful than what people believe. It increases the long-term risk of developing lung disease, such as lung cancer and COPD (chronic obstructive pulmonary disease).
Recently popular coffee café Starbucks banned smoking 25 feet near its stores, Wall Street Journal reported. The ban was enforced across the stores 7,000 company-operated cafes in the U.S.

The fatality rate among hard drug users is 14 times higher than for the general population

Posted date: 11:42 AM / comment : 0 , ,

A new study analyses the risk factors and excess mortality among heroin and cocaine consumers admitted to treatment in Spain. The results reveal that the fatality rate among consumers of both drugs is 14.3 times higher than for the general population, while among those only using cocaine, it is 5.1 times higher.
hoffman, heroin, addict
(Photo : Keith Bedford/Reuters)
In Spain the majority of deaths related to cocaine are not correctly certified and therefore up until now very few studies have been carried out that analyse the consequences of consuming these drugs in terms of mortality.
"Death certificates rarely include any reference to these substances in the information contained therein," SINC was informed by Gregorio Barrio, a researcher at the Carlos III Health Institute in Madrid and one of the authors of this new study.
This, says Barrio, is because very often the immediate cause of death in these cases is an unspecified health problem, such as a myocardial infarction or suicide, which may be caused by factors unrelated to cocaine or a number of reasons.
"Also, when signs of cocaine consumption before death are revealed during possible forensic and toxicological investigations, the original certified cause of death generally goes uncorrected, thus being included in mortality statistics devoid of the surname 'cocaine'," adds the researcher.
Faced with the difficulty of directly quantifying the deaths related to cocaine based on general mortality statistics, the researchers compared mortality rates among a group of heroin and cocaine users with that of people among the general population of the same age and sex.
For this study, published in the Journal of Substance Abuse Treatment, two groups of cocaine users were taken, one of 8,825 people that also consumed heroin and another of 11,905 people who did not use this substance.
All the participants were admitted to treatment for psychoactive drug abuse or dependence in Madrid or Barcelona between 1997 and 2007; they were aged between 15 and 49 years at the time of being recruited and were cross-referenced with the general mortality register for the 1997-2008 period, in order to observe their vital condition.
Excess mortality - adjusted death rate ratio between participants and the general population - was considerable in both groups of participants. In fact, the death rate among those who also consumed heroin was 14.3 times higher than for the general population, while among those who did not consume this substance, it was 5.1 times higher.
The results also revealed that was a greater chance of men dying than women among those who also consumed heroin (1.5 times), while no differences were found according to sex among those who did not consume this substance.
The authors stated that the excess mortality found is within the range of the results published in the past in other countries (4-12 times higher).
Other related factors
Apart from the use of heroine, other factors related to the greater risk of death were identified, such as the absence of regular employment, drug use by injection or consuming cocaine on a daily basis.
"This excess mortality may be due to the consumption of cocaine or heroin, but there are also other factors that may be different among the general population and the participants, such as mental disorders, personality traits, social conditions, etc.," said Barrio.
Another interesting finding was that the excess mortality with regard to the general population of the same age and sex was significantly higher among women than among men, particularly among those who consumed cocaine but not heroin (8.6 times in women compared with 3.5 times in men).
"This information does not mean that female cocaine consumers have a significantly greater risk of death than their male counterparts, but that the relative increased risk of female cocaine consumers compared with women in the general population of their same age (with a very low death risk) is higher than the relative increase of consumers compared with men among the general population," he clarified.
For the authors, the conclusions of this work are important because they will enable better estimates to be obtained for mortalities attributable to cocaine and they also show that interventions need to be increased in order to reduce the consumption of these substances and the damage caused by them.

10 Futuristic Materials

Posted date: 7:05 AM / comment : 0 , ,

10 Futuristic Materials


1. Aerogel




Aerogel protecting crayons from a blowtorch.

 


This tiny block of transparent aerogel is supporting a brick weighing 2.5 kg. The aerogel’s density is 3 mg/cm3.

Aerogel holds 15 entries in the Guinness Book of Records, more than any other material. Sometimes called “frozen smoke”, aerogel is made by the supercritical drying of liquid gels of alumina, chromia, tin oxide, or carbon. It’s 99.8% empty space, which makes it look semi-transparent. Aerogel is a fantastic insulator — if you had a shield of aerogel, you could easily defend yourself from a flamethrower. It stops cold, it stops heat. You could build a warm dome on the Moon. Aerogels have unbelievable surface area in their internal fractal structures — cubes of aerogel just an inch on a side may have an internal surface area equivalent to a football field. Despite its low density, aerogel has been looked into as a component of military armor because of its insulating properties.

 
 

2. Carbon nanotubes



Carbon nanotubes are long chains of carbon held together by the strongest bond in all chemistry, the sacred sp2 bond, even stronger than the sp3 bonds that hold together diamond. Carbon nanotubes have numerous remarkable physical properties, including ballistic electron transport (making them ideal for electronics) and so much tensile strength that they are the only substance that could be used to build a space elevator. The specific strength of carbon nanotubes is 48,000 kN·m/kg, the best of known materials, compared to high-carbon steel’s 154 kN·/kg. That’s 300 times stronger than steel. You could build towers hundreds of kilometers high with it.
 
 

3. Metamaterials



“Metamaterial” refers to any material that gains its properties from structure rather than composition. Metamaterials have been used to create microwave invisibility cloaks, 2D invisibility cloaks, and materials with other unusual optical properties. Mother-of-pearl gets its rainbow color from metamaterials of biological origin. Some metamaterials have a negative refractive index, an optical property that may be used to create “Superlenses” which resolve features smaller than the wavelength of light used to image them! This technology is called subwavelength imaging. Metamaterials would used in phased array optics, a technology that could render perfect holograms on a 2D display. These holograms would be so perfect that you could be standing 6 inches from the screen, looking into the “distance” with binoculars, and not even notice it’s a hologram.
 
 

4. Bulk diamond



We’re starting to lay down thick layers of diamond in CVD machines, hinting towards a future of bulk diamond machinery. Diamond is an ideal construction material — it’s immensely strong, light, made out of the widely available element carbon, nearly complete thermal conductivity, and has among the highest melting and boiling points of all materials. By introducing trace impurities, you can make a diamond practically any color you want. Imagine a jet, with hundreds of thousands of moving parts made of fine-tuned diamond machinery. Such a craft would be more powerful than today’s best fighter planes in the way an F-22 is better than the Red Baron’s Fokker Dr.1.
 
 

5. Bulk fullerenes



Diamonds may be strong, but aggregated diamond nanorods (what I call amorphous fullerene) are stronger. Amorphous fullerene has a isothermal bulk modulus of 491 gigapascals (GPa), compared to diamond’s 442 GPa. As we see in the image, the nanoscale structure of the fullerene gives it a beautiful iridescent appearance. Fullerenes can be made substantially stronger than diamond, but for greater energy cost. After a “Diamond Age” we may eventually transition to a “Fullerene Age” as our technology gets even more sophisticated.

6. Amorphous metal



Amorphous metals, also called metallic glasses, consist of metal with a disordered atomic structure. They can be twice as strong as steel. Because of their disordered structure, they can disperse impact energy more effectively than a metal crystal, which has points of weakness. Amorphous metals are made by quickly cooling molten metal before it has a chance to align itself in a crystal pattern. Amorphous metals may the military’s next generation of armor, before they adopt diamondoid armor in mid-century. On the green side of things, amorphous metals have electronic properties that improve the efficiency of power grids by as much as 40%, saving us thousands of tons of fossil fuel emissions. 
 
 

7. Superalloys



A superalloy is a generic term for a metal that can operate at very high temperatures, up to about 2000 °F (1100 °C). They are popular for use in the superhot turbine areas of jet engines. They are used for more advanced oxygen-breathing designs, such as the ramjet and scramjet. When we’re flying through the sky in hypersonic craft, we’ll have superalloys to thank for it.
 
 

8. Metal foam



Metal foam is what you get when you add a foaming agent, powdered titanium hydride, to molten aluminum, then let it cool. The result is a very strong substance that is relatively light, with 75–95% empty space. Because of its favorable strength-to-weight ratio, metal foams have been proposed as a construction material for space colonies. Some metal forms are so light that they float on water, which would make them excellent for building floating cities, like those analyzed by Marshall T. Savage in one of my favorite books, The Millennial Project. 
 
 

9. Transparent alumina



Transparent alumina is three times stronger than steel and transparent. The number of applications for this are huge. Imagine an entire skyscraper or arcology made largely of transparent steel. The skylines of the future could look more like a series of floating black dots (opaque private rooms) rather than the monoliths of today. A huge space station made of transparent alumina could cruise in low Earth orbit without being a creepy black dot when it passes overhead. And hey… transparent swords!
 
 

10. E-textiles



If you meet up and talk to me in 2020, I’ll likely be covered in electronic textiles. Why carry some electronic gadget you can easily lose when we can just wear our computers? We’ll develop clothing that can constantly project the video of our choosing (unless it turns out being so annoying that we ban it). Imagine wearing a robe covered in a display that actually projects the night sky in realtime. Imagine talking to people over the “phone” just by making a hand gesture and activating electronics in your lapel, then merely thinking about what you want to say (thought-to-speech interfaces). The possibilities of e-textiles are limitless.
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