Curious Cat Science and Engineering Blog

Modeling Weight Loss Over the Long Term

curiouscat — Thu, 17 May 2012 12:06:26 +0000

Researchers at the National Institutes of Health have created a mathematical model of what happens when people of varying weights, diets and exercise habits try to change their weight. The findings challenge the commonly held belief that eating 3,500 fewer calories, or burning them off exercising, will result in a pound of weight loss.

Instead, the researchers’ computer simulations indicate that this assumption overestimates weight loss because it fails to account for how metabolism changes. The computer simulations show how these metabolic changes can significantly differ among people.

However, the computer simulation of metabolism is meant as a research tool and not as a weight-loss guide for the public. The computer program can run simulations for changes in calories or exercise that would never be recommended for healthy weight loss. The researchers hope to use the knowledge gained from developing the model and from clinical trials in people to refine the tool for everyone.

“This research helps us understand why one person may lose weight faster or slower than another, even when they eat the same diet and do the same exercise,” said Kevin Hall, Ph.D., an obesity researcher and physicist at the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases. “Our computer simulations can then be used to help design personalized weight management programs to address individual needs and goals.”

The online simulation tool based on the model enables researchers to accurately predict how body weight will change and how long it will likely take to reach weight goals based on a starting weight and estimated physical activity. The tool simulates how factors such as diet and exercise can alter metabolism over time and thereby lead to changes of weight and body fat.

The team found that people’s bodies adapt slowly to changes in dietary intake. They also found heavier people can expect greater weight change with the same change in diet, though reaching a stable body weight will take them longer than people with less fat.

The model also points to a potential simplified method to approximate weight loss in an average overweight person. An adult who has a body mass index (a measure of a person’s weight in relation to his or her height) between 25 and 29.9 is considered overweight. One example: For every pound you want to lose, permanently cut 10 calories from your current intake per day. At that rate, it will take about one year to achieve half of the total weight loss, and almost all of the weight loss will have occurred by three years. This calculation shows how long it takes to achieve a weight-loss goal for a single permanent change of diet or exercise.

A Mathematical Challenge to Obesity

…there’s a time constant that’s an important factor in weight loss. That’s because if you reduce your caloric intake, after a while, your body reaches equilibrium. It actually takes about three years for a dieter to reach their new “steady state.” Our model predicts that if you eat 100 calories fewer a day, in three years you will, on average, lose 10 pounds — if you don’t cheat.

Another finding: Huge variations in your daily food intake will not cause variations in weight, as long as your average food intake over a year is about the same. This is because a person’s body will respond slowly to the food intake.
…
The price of food plummeted, while the number of calories available to the average American grew by about 1,000 a day.

Well, what do people do when there is extra food around? They eat it! This, of course, is a tremendously controversial idea. However, the model shows that increase in food more than explains the increase in weight.
…
I think the food industry doesn’t want to know it. And ordinary people don’t particularly want to hear this, either. It’s so easy for someone to go out and eat 6,000 calories a day. There’s no magic bullet on this. You simply have to cut calories and be vigilant for the rest of your life.

Video of Young Richard Feynman Talking About Scientific Thinking

curiouscat — Tue, 15 May 2012 22:55:48 +0000

The enjoyable video above shows a young Richard Feynman discussing how scientific thinking can advance our understanding of the world.

Repair Cafes in The Netherlands

curiouscat — Sun, 13 May 2012 17:13:24 +0000

Repair Cafes in The Netherlands Give Life Back to Broken Objects

A new brand of DIY self-sufficiency is spreading across The Netherlands. Skilled craftswomen, mechanics, seamstresses, and handypersons are banding together to resist disposable consumer culture. It is the rise of the Repair Cafe, a place where neighbors get together to extend the life of their material belongings. “Fixers” mend clothes, restore furniture, rehabilitate electrical appliances, and enjoy each other’s company while industriously toiling away. The first cafe was founded by Martine Postma in Amsterdam in October of 2009. Today, there are 20 fully operational Repair Cafes, and 50 more in the planning stages.

I really like these efforts. We throw away too much stuff that has plenty of useful life left. Also it is a great way to build community. And it is an interesting way to learn about products we use everyday (both by fixing them and having your items fixed). The throw away culture is something we should aim to change. By these actions and also by engineers designing products to be fixed instead of thrown away. I donated to a similar fixer collective in Brooklyn via Kickstarter.

Video of Kittens Being Rescued by Their Mother

curiouscat — Fri, 11 May 2012 13:59:36 +0000

Repost of this fun cat video and a reminder to thank your mother for all the times she saved you from your version of the slide. Have a happy friday. Maybe you should forward this video to your Mom with a note of thanks and make it a happy one for her too.

Largest Google Summer of Code Ever

curiouscat — Tue, 08 May 2012 22:53:33 +0000

Google summer of code allows college students to work on open source software projects during the summer and get a $5,000 stipend from Google.

Google Summer of Code 2012 by the Numbers

This 8th year of Google Summer of Code is the largest yet. More mentoring organizations received more applications from more students than ever before. We received a record number of applications – 6685 – from 4258 students from 98 countries to work with the 180 selected mentoring organizations.

We also accepted more students this year: 1,212 from 69 countries. This year India supplied the largest number of students, 227.

USA has 172 students, Germany 72, Russia 56 and China 45. This year set the highest percentage of women (self identified) yet. Guess what percentage. If you guessed 8.3% you are right.

Projects from the following organizations/software projects are included this year: Apache Software Foundation, Debian Project, Electronic Frontier Foundation/The Tor Project, GIMP, haskell.org, The JRuby Project, OpenStreetMap, Python Software Foundation, R project for statistical computing, Twitter, Wikimedia Foundation.

Google provides a stipend of 5,000 USD to the student and $500 to the mentoring organization. That puts Google’s support at over $6,500,000 this year.

Using Nanocomposites to Improve Dental Filling Performance

curiouscat — Sun, 06 May 2012 12:14:31 +0000

After a dentist drills out a decayed tooth, the cavity still contains residual bacteria. Professor Huakun (Hockin) Xu says it is not possible for a dentist to remove all the damaged tissue, so it’s important to neutralize the harmful effects of the bacteria, which is just what the new nanocomposites are able to do.

Rather than just limiting decay with conventional fillings, the new composite he has developed is a revolutionary dental weapon to control harmful bacteria, which co-exist in the natural colony of microorganisms in the mouth.

“Tooth decay means that the mineral content in the tooth has been dissolved by the organic acids secreted by bacteria residing in biofilms or plaques on the tooth surface. These organisms convert carbohydrates to acids that decrease the minerals in the tooth structure,” says Xu, director of the Division of Biomaterials and Tissue Engineering in the School’s Department of Endodontics, Prosthodontics and Operative Dentistry.

The researchers also have built antibacterial agents into primer used first by dentists to prepare a drilled-out cavity and into adhesives that dentists spread into the cavity to make a filling stick tight to the tissue of the tooth. “The reason we want to get the antibacterial agents also into primers and adhesives is that these are the first things that cover the internal surfaces of the tooth cavity and flow into tiny dental tubules inside the tooth,” says Xu.

The main reason for failures in tooth restorations, says Xu, is secondary caries or decay at the restoration margins. Applying the new primer and adhesive will kill the residual bacteria, he says.

Fillings made from the School of Dentistry’s new nanocomposite, with antibacterial primer and antibacterial adhesive, should last longer than the typical five to 10 years, though the scientists have not thoroughly tested longevity. Xu says a key component of the new nanocomposite and nano-structured adhesive is calcium phosphate nanoparticles that regenerate tooth minerals. The antibacterial component has a base of quaternary ammonium and silver nanoparticles along with a high pH. The alkaline pH limits acid production by tooth bacteria.

The new products have been laboratory tested using biofilms from saliva of volunteers. The Xu team is planning to next test its products in animal teeth and in human volunteers in collaboration with the Federal University of Ceara in Brazil.

Bringing products into the market, after preliminary research success is very difficult. I once made some money shorting a stock, Enamelon, that was targeting the regeneration of enamel. Short selling is when you sell it before you buy it, anticipating a decline in price. This research on does seem to hold promise, I hope it pans out and we can take advantage of these improvements.

Majority of Clinical Trials Don’t Provide Meaningful Evidence

curiouscat — Thu, 03 May 2012 10:32:23 +0000

The largest comprehensive analysis of ClinicalTrials.gov finds that clinical trials are falling short of producing high-quality evidence needed to guide medical decision-making.

The analysis, published today in the Journal of the American Medical Association, found the majority of clinical trials is small, and there are significant differences among methodical approaches, including randomizing, blinding and the use of data monitoring committees.

This is a critical issue as medical studies continue to leave quite a bit to be desired. Even more importantly the failure to systemically study and share evidence of effectiveness once treatments are authorized leaves a great deal to be desired. On top of leaving quite a bit to be desired, the consequences are serious. If we make mistakes for example in how we date fossils it matters but it is unlikely to cause people their lives or health. Failure to adequately manage and analyze health care experiments may very well cost people their health or lives.

“Our analysis raises questions about the best methods for generating evidence, as well as the capacity of the clinical trials enterprise to supply sufficient amounts of high quality evidence to ensure confidence in guideline recommendations,” said Robert Califf, MD, first author of the paper, vice chancellor for clinical research at Duke University Medical Center, and director of the Duke Translational Medicine Institute.

The analysis was conducted by the Clinical Trials Transformation Initiative (CTTI), a public-private partnership founded by the Food and Drug Administration (FDA) and Duke. It extends the usability of the data in ClinicalTrials.gov for research by placing the data through September 27, 2010 into a database structured to facilitate aggregate analysis.

“Since 2007, the Food and Drug Administration Amendment Act has required registration of clinical trials, and the expanded scope and rigor of trial registration policies internationally is producing more complete data from around the world,” stated Deborah Zarin, MD, director, ClinicalTrials.gov, and assistant director for clinical research projects, NLM. “We have amassed over 120,000 registered clinical trials. This rich repository of data has a lot to say about the national and international research portfolio.”

“Analysis of the entire portfolio will enable the many entities in the clinical trials enterprise to examine their practices in comparison with others,” says Califf. “For example, 96% of clinical trials have 1000 participants, or fewer, and 62% have 100, or fewer. While there are many excellent small clinical trials, these studies will not be able to inform patients, doctors, and consumers about the choices they must make to prevent and treat disease.”

An analysis-ready copy of the database is now available at www.ctti-clinicaltrials.org. Specialists from numerous therapeutic areas are now scrutinizing the contents to better understand how the number and characteristics of clinical trials match the perceived needs of the research communities.

New Blog with Simple Demonstrations and Scientific Explanations

curiouscat — Wed, 02 May 2012 05:25:50 +0000

Try this at home is a new blog by Dr Mark Lorch, a chemistry lecturer at the University of Hull, with instructions for the citizen scientist. This example shows how to move a can with a ballon without touching the can.

The posts include instructions on how to do these simple demonstrations and a nice explanation on the scientific reason for what is going on:

Rubbing the balloon on your hair charges it up with static electricity which makes the balloon negatively charged. When you put the balloon near the can it pushes electrons (which are also negatively charged) to the other side of the can. This makes the side which is nearest the balloon positively charged. Positive charges are attracted to negative charges so the can moves towards the balloon.

It is quite a nice site (especially if you have kids interested in science or are a kid interested in science – no matter how old you are), add it to your RSS reader. Here are some more science blogs you may enjoy.

Book Explores Adventures in Making

curiouscat — Sat, 28 Apr 2012 15:42:02 +0000

Made by Hand by Mark Frauenfelder, the editor-in-chief of Make magazine. explores his adventures in the world of do-it-yourself.

Frauenfelder spent a year trying a variety of offbeat projects such as keeping chickens and bees, tricking out his espresso machine, whittling wooden spoons, making guitars out of cigar boxes, and doing citizen science with his daughters in the garage. His whole family found that DIY helped them take control of their lives, offering deeply satisfying alternatives for spending time together. Working with their hands and minds helped them feel more engaged with the world around them.

Frauenfelder also profiles fascinating “alpha makers” leading various DIY movements and grills them for their best tips and insights. He offers a unique perspective on how earning a few calluses can be far more rewarding than another trip to the mall.