October 23, 2007, 8:53 PM CT

Bus Scheduling Algorithm Picks Up the Slack

A prizewinning paper by a USC Viterbi School engineer elegantly solves a basic transit scheduling problem, potentially meaning shorter waits for riders.

The question: how much slack should be schedulers of a bus or tram line add to keep operations from bunching up? Maged Dessouky, a professor in the Viterbi School's Daniel J. Epstein department of Industrial and Systems engineering joined with two colleagues to analyze this problem.

Slack time is extra time built into a bus schedule to accommodate unexpected delays. The paper published in November 2006 issue of Transportation Science notes, "if slack time is insufficient, buses are unlikely to be able to catch up with the schedule when they fall behind, deteriorating reliability. But too much slack time reduces service frequency, which may inconvenience passengers".

For the simplest case, a single vehicle traveling in a loop, the algorithm reported in the paper gives an exact number, based on the size of the loop and the distribution of the of the travel time delay. The analysis also provides a way to approximate the effect of adding more busses to the loop.

The calculations are not simple. The effects that the equations have to model involve human behavior that is easy to describe, but hard to quantify. For example, if trains or buses are spaced close together (less than 10 minutes apart, typically), travelers tend not to consult schedules or expect vehicles to arrive exactly on time, and buses can leave early without upsetting travel plans. If buses are an hour apart, this isn't true......... Posted by: Beverly      Read more         Source

Fri, 19 Oct 2007 01:58:35 GMT

Dr Crippen innocent

"For nearly 100 years his name has been a byword for murder most foul, but Hawley Crippen, the infamous doctor hanged for poisoning and dismembering his British wife, may have been innocent, new research suggests."
(The Times)
Finally, the truth has been established. An innocent man was led to the gallows. Great uncle Hawley did not poison Aunty Cora. That, of course, has always been my belief. I make no comment about the speculative and unsubstantiated allegations that he was involved in botched back street abortions.Labels: Dr Crippen Posted by: Dr John Crippen      Read more     Source

October 4, 2007, 5:02 AM CT

Physicists Tackle Knotty Puzzle

Electrical cables, garden hoses and strands of holiday lights seem to get themselves hopelessly tangled with no help at all. Now research initiated by an undergraduate student at the University of California, San Diego has resulted in the first model of how knots form.

The study, published this week in the journal Proceedings of the National Academy of Sciences, investigated the likelihood of knot formation and the types of knots formed in a tumbled string. The scientists say they were interested in the problem because it has a number of applications, including to the biophysics research questions their group commonly studies.

"Knot formation is important in a number of fields," said Douglas Smith, an assistant professor of physics who was the senior author on the paper. "For example, knots often form in DNA, which is a long string-like molecule. Cells have enzymes that undo the knots by cutting the DNA strands so that they can pass through each other. Certain anti-cancer drugs stop tumor cells from dividing by blocking the unknotting of DNA".

Dorian Raymer, a research assistant working with Smith, initiated the study because he was interested in knot theory-the branch of mathematics that uses formulae to distinguish unique knots. Raymer was an undergraduate major in physics when he did the work. Smith said his own interest was piqued when he discovered that no one really knew how knots formed......... Posted by: Beverly      Read more         Source

Tue, 02 Oct 2007 03:44:42 GMT

Global Warming, Water Crisis: Reality Now

Kashmir's rivers and streams have decreased by two-thirds, and many glaciers have completely disappeared over the last four decades. Average temperatures have risen between 2.6 and 4.2 degrees Fahrenheit in the last two decades, depending on where you are - putting the state's water supply, and people, in extreme danger of extinction.

I don't think that's an exaggeration either. Depending on who you ask, Kashmir has lost anywhere between 42,000 and 60,000 people during these last 18 years of violent unrest. Now add on the water problem, and you have a recipe for total disaster.

"The rapid melting of Himalayan glaciers will first increase the volume of water in rivers causing widespread flooding," said Jennifer Morgan, head of WWF's global climate change program. "But in a few decades this situation will change and the water level in rivers will decline, meaning massive economic and environmental problems for people in Western China, Nepal and Northern India." - Source: ENN article

....and water levels are already starting to decrease. Nepal, China, India - they are all seeing huge decreases in water levels. Experts say a quarter of the world's glaciers could be gone by 2050, half by 2100. I think it might be sooner - the experts have been surprised by how fast the glaciers melt before. Either way, Asia is in big trouble. Most of their water is purely from glacier fed streams.

About 67 percent of the nearly 12,124 square miles of Himalayan glaciers are receding and in the long run as the ice diminishes, glacial runoffs in summer and river flows will also go down, leading to severe water shortages in the region. - Source: ENN article

It's almost sickening to think, but I feel like I'm in a science fiction novel. Posted by: Miche      Read more     Source

Tue, 18 Sep 2007 12:54:29 GMT

Pyrostegia venusta

Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Thank you to codiferous@Flickr for sharing another photograph with BPotD (original via BPotD Flickr Group Pool). It's much appreciated.

The genus name Pyrostegia is derived from the Greek pyr, meaning “fire” and stege, meaning “covering” — combined, this is a reference to the colourful corolla. Flame vine or flaming trumpet is native to central South America (Brazil, northeastern Argentina, Paraguay, and the site of today's photograph, Bolivia).

The University of Florida Institute of Food and Agricultural Science Extension has a factsheet on Pyrostegia venusta, as does the site for Pacific Island Ecosystems at Risk (the latter focuses on the plant's invasive potential). Posted by: Daniel Mosquin      Read more     Source

September 12, 2007, 6:34 PM CT

Biodegradable polymers to deliver genes

In work that could lead to safe and effective techniques for gene treatment, MIT scientists have found a way to fine-tune the ability of biodegradable polymers to deliver genes.

Gene treatment, which involves inserting new genes into patients' cells to fight diseases like cancer, holds great promise but has yet to realize its full potential, in part because of safety concerns over using viruses to carry the genes.

The new MIT work, published this week in Advanced Materials, focuses on creating gene carriers from synthetic, non-viral materials. The team is led by Daniel Anderson, research associate in MIT's Center for Cancer Research.

"What we wanted to do is start with something that's very safe--a biocompatible, degradable polymer--and try to make it more effective, instead of starting with a virus and trying to make it safer," said Jordan Green, a graduate student in biological engineering and co-first author of the paper.

Gregory Zugates, a former graduate student in chemical engineering now at WMR Biomedical, Inc., is also a co-first author of the paper.

Gene treatment has been a field of intense research for nearly 20 years. More than 1,000 gene-therapy clinical trials have been conducted, but to date there are no FDA-approved gene therapies. Most trials use viruses as carriers, or vectors, to deliver genes......... Posted by: Beverly      Read more         Source

September 10, 2007, 9:10 PM CT

Multi-million research project on rice epigenetics

Using a novel "deep sequencing" technology that can in one fell swoop decode 50 million sequences representing well over a billion bases of DNA, a research team led by University of Delaware researchers is working to unmask where, why and how certain genes are switched on or off in rice--a crop vital to the world's food supply.

The goal of the four-year project, which is supported by a $5.3-million grant from the National Science Foundation (NSF), is to advance scientific understanding of the rice epigenome--the series of biochemical modifications of the rice DNA that can toggle a gene on or, on the other hand, silence it. Ultimately, the research may lead to the development of hardier strains of rice, as well as shed light on similar mechanisms at work in corn and other important cereal grains that are closely correlation to rice.

Blake Meyers, associate professor of plant and soil sciences at UD, is the principal investigator on the project, which also involves Guo-Liang Wang, a rice biologist from Ohio State University; Steven Jacobsen, an expert in epigenetics, and computer scientist Matteo Pellegrini, both from the University of California at Los Angeles; and Yulin Jia, a plant pathologist at the U.S. Department of Agriculture's Dale Bumpers National Rice Research Center in Stuttgart, Ark......... Posted by: Beverly      Read more         Source

Thu, 06 Sep 2007 02:27:39 GMT

Anacardium occidentale

Thanks to “Shyzaboy@UBC BG Forums” of Troutville, Virginia for today's photograph from Panama. Images from the tropics are very welcome!

Although native to northeast Brazil, the cashew is now cultivated in tropical areas throughout the world. Illustrated in today's photograph are both the double-shelled kidney-shaped fruit containing the cashew nut and the apple-like pseudofruit (cashew apple). Both the cashew nut and cashew apple are edible, but extra effort is required to extract the cashew nut; its double-shell contains urushiol, the same oil found in poison ivy.

Read more about cashew via Wikipedia and Morton's Fruits of Warm Climates. Posted by: Daniel Mosquin      Read more     Source

Sun, 02 Sep 2007 02:42:32 GMT

Gelatin from corn, a first

Boston 8/22/07:: Scientists meeting in Boston last week announced an advance toward turning corn plants into natural factories producing gelatin.

Currently gelatin for food and used by the pharmaceutical industry for manufacturing capsules is derived almost exclusively from animal products. The advance, described Wednesday at the 234th national meeting of the American Chemical Society, may lead to a safe, inexpensive source of this protein.

About 55,000 tons of animal-sourced gelatin are used each year to produce capsules and tablets for medicinal purposes. Plant-derived recombinant gelatin would address concerns about the possible presence of infectious agents in animal by-products and the lack of traceability of the source of the raw materials currently used to make gelatin. Resourcing plant materials to recover and purify recombinant gelatin has remained a challenge because only very low levels accumulate at the early stages of the development process.

Now, scientists at Iowa State University in Ames and FibroGen, Inc., in South San Francisco say they have developed a purification process to recover these small quantities of recombinant gelatin present in the early generations of transgenic corn.

The studies establish transgenic corn as a viable way to produce gelatin and potentially other products, Said Charles Glatz, Ph.D., a professor of chemical & biological engineering at Iowa State University in Ames, Iowa who worked with others including Cheng Zhang a doctoral student at Iowa State to develop the procedure.
In time, researchers may also be able to develop a variety of "designer" gelatins, with specific molecular weights and properties tailored to suit various needs.
"Corn is an ideal production unit, because it can handle high volumes at a low cost," Glatz said. In addition the recombinant gelatin is free from the safety concerns of using meat byproducts.

The group is now working to refine the method and boost the overall recombinant protein yields in corn. Though the procedure requires more testing, Glatz says the technique could someday be used to produce high-grade gelatin in a safe and inexpensive manner.

Overall costs could be further reduced by combining the production of gelatin in corn with the extraction of non-protein parts of the grain - such as oils and starches - that are now grown and harvested for biodiesel and ethanol production, he adds.

Greener Magazine Posted by: Greener Magazine      Read more     Source

Tue, 21 Aug 2007 03:24:04 GMT

Brachycereus nesioticus

Botany Photo of the Day will have brief written entries on weekends, holidays and my vacations from April through September. – Daniel

Thanks again to Krystyna Szulecka, for sharing today's photograph with us (original in this thread on the UBC BG Forums). See more of Krystyna's images by searching for “Krystyna” on the FLPA web site.

Lava cactus is endemic to the volcanically-formed Galápagos Islands, where it is a colonizer species of lava fields (hence the common name). Due to its narrow geographic distribution, it is listed as a vulnerable species on the IUCN Red List.

More photographs can be seen via Thomas Schoepke or CalPhotos. Posted by: Daniel Mosquin      Read more     Source