Friday, September 18, 2009
Researchers at Baylor College of Medicine say nicotine, the addictive component in cigarettes, "tricks" the brain into creating memory associations between environmental cues and smoking behavior. The findings appear in the current issue of the journal Neuron.
"Our brains normally make these associations between things that support our existence and environmental cues so that we conduct behaviors leading to successful lives. The brain sends a reward signal when we act in a way that contributes to our well being," said Dr. John A. Dani, professor of neuroscience at BCM and co-author of the study. "However, nicotine commandeers this subconscious learning process in the brain so we begin to behave as though smoking is a positive action."
Dani said that environmental events linked with smoking can become cues that prompt the smoking urge. Those cues could include alcohol, a meal with friends, or even the drive home from work. To understand why these associations are so strong, Dani and Dr. Jianrong Tang, instructor of neuroscience at BCM and co-author of the report, decided to record brain activity of mice as they were exposed to nicotine, the addictive component of tobacco.
The mice were allowed to roam through an apparatus with two separate compartments. In one compartment, they received nicotine. In the other, they got a benign saline solution. Later, the researchers recorded how long the mice spent in each compartment. They also recorded brain activity within the hippocampus, an area of the brain that creates new memories.
"The brain activity change was just amazing," Dani said. "Compared to injections of saline, nicotine strengthened neuronal connections – sometimes up to 200 percent. This strengthening of connections underlies new memory formation."
Consequently, mice learned to spent more time in the compartment where the nicotine was administered compared to the one where saline was given to them.
"We found that nicotine could strengthen neuronal synaptic connections only when the so called reward centers sent a dopamine signal. That was a critical process in creating the memory associations even with bad behavior like smoking."
Dani said understanding mechanisms that create memory could have implications in future research and treatments for memory disorders, such as Alzheimer's disease, and for dopamine signaling disorders, such as Parkinson's disease.
Baylor College of Medicine
The bacteria Wall is studying are bio-corrosives and can change the solubility of heavy metals. They can take uranium and convert it to uraninite, a nearly insoluble substance that will sink to the bottom of a lake or stream. Wall is looking into the bacteria's water cleansing ability and how long the changed material would remain inert.
Wall's research could also be beneficial to heavy metal pollution from storage tanks and industrial waste. The bacteria are already present in more than 7,000 heavy metal contaminated sites, but they live in a specific range of oxygen and temperature, making them difficult to control.
"Our research must be done in the absence of air," Wall said. "Obviously, none but the most committed – and stubborn – will work with them."
Even if an oxygen-tolerant strain were developed, there are still multiple factors that would make applying the bacteria challenging, and these microbes can contribute to massive iron corrosion.
"Knowledge of the way bacteria live in the environment, in microbial communities, is still in its infancy," Wall said. "We just don't know a lot about the communication systems among microbes."
Wall and researchers from the Lawrence Berkley National Laboratory in California are investigating the bacterium's basic genetics and hope to determine its growth limits and activity in natural settings, including how to make its interactions with metals sustainable. They have already identified a few genes that are critical to converting uranium.
(Photo: MIZZOU magazine)
"Aquaculture is set to reach a landmark in 2009, supplying half of the total fish and shellfish for human consumption," the authors wrote. Between 1995 and 2007, global production of farmed fish nearly tripled in volume, in part because of rising consumer demand for long-chain omega-3 fatty acids. Oily fish, such as salmon, are a major source of these omega-3s, which are effective in reducing the risk of cardiovascular disease, according to the National Institutes of Health.
"The huge expansion is being driven by demand," said lead author Rosamond L. Naylor, a professor of environmental Earth system science at Stanford University and director of the Stanford Program on Food Security and the Environment. "As long as we are a health-conscious population trying to get our most healthy oils from fish, we are going to be demanding more of aquaculture and putting a lot of pressure on marine fisheries to meet that need."
To maximize growth and enhance flavor, aquaculture farms use large quantities of fishmeal and fish oil made from less valuable wild-caught species, including anchoveta and sardine. "With the production of farmed fish eclipsing that of wild fish, another major transition is also underway: Aquaculture's share of global fishmeal and fish oil consumption more than doubled over the past decade to 68 percent and 88 percent, respectively," the authors wrote.
In 2006, aquaculture production was 51.7 million metric tons, and about 20 million metric tons of wild fish were harvested for the production of fishmeal. "It can take up to 5 pounds of wild fish to produce 1 pound of salmon, and we eat a lot of salmon," said Naylor, the William Wrigley Senior Fellow at Stanford's Woods Institute for the Environment and Freeman Spogli Institute for International Studies.
One way to make salmon farming more environmentally sustainable is to simply lower the amount of fish oil in the salmon's diet. According to the authors, a mere 4 percent reduction in fish oil would significantly reduce the amount of wild fish needed to produce 1 pound of salmon from 5 pounds to just 3.9 pounds. In contrast, reducing fishmeal use by 4 percent would have very little environmental impact, they said.
"Reducing the amount of fish oil in the salmon's diet definitely gets you a lot more bang for the buck than reducing the amount of fishmeal," Naylor said. "Our thirst for long-chain omega-3 oils will continue to put a lot of strain on marine ecosystems, unless we develop commercially viable alternatives soon."
Naylor and her co-authors pointed to several fish-feed substitutes currently being investigated, including protein made from grain and livestock byproducts, and long-chain omega-3 oils extracted from single-cell microorganisms and genetically modified land plants. "With appropriate economic and regulatory incentives, the transition toward alternative feedstuffs could accelerate, paving the way for a consensus that aquaculture is aiding the ocean, not depleting it," the authors wrote.
Fishmeal and fish oil are important staples at farms that produce carnivorous fish, including salmon, trout and tuna. But vegetarian species, such as Chinese carp and tilapia, can be raised on feed made from plants instead of wild-caught fish. That's one reason why farm-raised vegetarian fish have long been considered environmentally friendly.
In the early 1990s, vegetarian fish farms began adding small amounts of fishmeal in their feed to increase yields. However, between 1995 and 2007, farmers actually reduced the share of fishmeal in carp diets by 50 percent and in tilapia diets by nearly two-thirds, according to the PNAS report. Nevertheless, in 2007, tilapia and carp farms together consumed more than 12 million metric tons of fishmeal—more than 1.5 times the amount used by shrimp and salmon farms combined.
"Our assumption about farmed tilapia and carp being environmentally friendly turns out to be wrong in aggregate, because the sheer volume is driving up the demand," Naylor said. "Even the small amounts of fishmeal used to raise vegetarian fish add up to a lot on a global scale." Removing fishmeal from the diet of tilapia and carp would have a very positive impact on the marine environment, she added.
On the policy front, Naylor pointed to California's Sustainable Oceans Act and the proposed National Offshore Aquaculture Act, which call for reductions in the use of fishmeal and fish oil in feeds. She also applauded plans by the National Oceanographic and Atmospheric Administration to develop a comprehensive national policy that addresses fisheries management issues posed by aquaculture. "No matter how much is done from the demand side, it is essential that there be regulation on the supply side as well," Naylor said. "You won't prevent the collapse of anchoveta, sardine and other wild fisheries unless those fisheries are carefully regulated."
Bigger speakers, bigger sound – this is the music lover’s creed. Flat panel loudspeakers offer an alternative to those who would rather not or cannot clutter up their homes with speakers. These speakers can be integrated inconspicuously on walls or in furniture. At the Internationale Funkausstellung IFA in Berlin from September 4 to 9, Fraunhofer scientists are presenting a completely new concept for ultra-flat loudspeakers that still deliver full sound reproduction.
Stereo, Dolby Digital, 5.1 or surround sound – music lovers have to accommodate an increasing number of loudspeakers in their rooms in order to obtain the most perfect sound. Good sound reproduction takes space, at least in the speakers. The loudspeaker membrane must have room to vibrate in order to maintain unimpaired enjoyment. Flat panel loudspeakers can be integrated almost invisibly into the surroundings to keep the multitude of loudspeakers from dominating the room. However, the quality of the sound in conventional models suffers if speakers are installed on walls or in furniture. In cooperation with Sennheiser electronic, scientists at the Fraunhofer Institute for Digital Media Technology IDMT in Ilmenau, Germany have now developed a special loudspeaker: ultra-flat, but resonant nevertheless.
“This new generation offers tonal balance and acoustic pressure at a level that will even allow the use in the professional movie or concert segment in the future,” reports Dr. Sandra Brix from IDMT. To make this possible, Brix and her team took their inspiration from the loudspeakers of premium headphones. “We are opening up a new application area for our highest quality electrodynamic headphone miniature loudspeakers in this alliance with Fraunhofer. Because of their compact overall depth, they are excellently suited for use in the flattest loudspeaker boxes, without any losses in tonal persuasiveness,” says Prof. Dr. Jürgen Peissig, head of the Signal Processing and High Frequency research department at Sennheiser electronic. They are arranged in groups, or "arrays" in the trade jargon, so that they allow audio quality that has not been seen in the past. “Even if these flat panel loudspeakers are placed directly on the wall or integrated into media equipment or furniture, they can reproduce a frequency range from 100 hertz to 20 kilohertz,” according to Brix. “This distinguishes our new concept from conventional flat panel loudspeakers that achieve response characteristics at this level only if kept at a certain minimum distance from the wall.”
Consequently, the ultra-flat loudspeakers are ideally suitable for multichannel systems and the IOSONO® audio system. Based on the principle of wave field synthesis, IOSONO® produces a realistic and spatial sound field throughout the entire listening area with the help of a large number of small loudspeakers arranged in a ring. Thanks to the new design and sound, this large number of loudspeakers can now be discreetly integrated into the surroundings. In the future, Dr. Brix is convinced, it will be possible to use this technology in all areas that call for an integration and reproduction of sound as invisible as possible. Automotive and aircraft construction are not the only areas calling for good sound at low weights and installation depths. Spas and hotels also seek to create surroundings that fascinate both eyes and ears equally. For example, the flat panel loudspeaker could inconspicuously disappear into the ambient design in form of a picture or decorative element.
(Photo: (c) Fraunhofer IDMT)
Outer space offers a new perspective for measuring economic growth, according to new research by three Brown University economists. In a National Bureau of Economic Research working paper, J. Vernon Henderson, Adam Storeygard, and David N. Weil suggest a new framework for estimating a country or region’s gross domestic product (GDP) by using satellite images of the area’s nighttime lights.
Reliable data on economic growth is hard to come by in many parts of the world — particularly in sub-Saharan Africa and other developing countries — and the data is often not calculated at all for cities. The authors cite the Penn World Tables, one of the standard compilations of data on income, which rank countries with grades A through D by the quality of their GDP and price data. While almost all industrialized countries receive a grade of A, nearly all sub-Saharan African countries get a grade of C or D, which is interpreted as roughly 30 or 40 percent margin of error. Several countries do not appear in the table, including Iraq, Myanmar, Somalia, and Liberia.
To improve these estimates, Henderson, Storeygard, and Weil suggest combining measured income data with the changes observed in a country’s “night lights” as seen from outer space. Using U.S. Air Force weather satellite picture composites, they look at changes in a region’s light density over a 10-year period. “Consumption of nearly all goods in the evening requires lights,” they write. “As income rises, so does light usage per person, in both consumption activities and many investment activities.”
When the researchers applied the new methodology to countries with low-quality national income data, the new estimates were significantly different. For example, in the Democratic Republic of Congo, lights suggest a 2.4-percent annual growth rate in GDP, while official estimates suggest a negative 2.6-percent growth over the same time period. The Congo appears to be growing faster than official estimates suggest. At the other end, Myanmar has an official growth rate of 8.6 percent a year, but the lights data imply only a 3.4-percent annual growth rate.
Henderson, Storeygard, and Weil say they don’t envision the lights density data as a replacement for official numbers, but when added to existing data from agencies like the World Bank, the lights density can provide a better indicator of how these economies really are performing.
“Our hope is that people start using this, either when they don’t have actual data on economic growth ... or when the numbers are pretty bad,” said Henderson, professor of economics. “This is just a way to get better estimates.”
The second portion of the paper establishes the first known causal relationship between local agriculture productivity and an increase in city incomes. The authors examined 541 cities in 18 African countries over a period of nine years, using rainfall as a way to measure “productivity shocks” to the rural areas. The authors conclude that an increase in agricultural output does in fact have substantial effects on local urban economic activity.
Storeygard, a fourth-year graduate student, added that the research was a true collaboration. Weil has written widely on various aspects of economic growth, while Henderson is interested in how to measure growth at a regional or subnational level. Storeygard has experience using geographic and satellite data. “It’s the kind of paper that used all three of our areas,” said Storeygard. “I don’t think any two of us would have been able to do this in quite the same way.”
(Photo: NOAA and USAF Weather Agency)
The team's findings were reported at the Society for General Microbiology's meeting at Heriot-Watt University, Edinburgh, today (7 September).
The researchers isolated a strain of Geobacter sulfurreducens which they called KN400 that grew prolifically on the graphite anodes of fuel cells. The bacteria formed a thick biofilm on the anode surface, which conducted electricity. The researchers found large quantities of pilin, a protein that makes the tiny fibres that conduct electricity through the sticky biofilm.
"The filaments form microscopic projections called pili that act as microbial nanowires," said Professor Lovley, "using this bacterial strain in a fuel cell to generate electricity would greatly increase the cell's power output."
The pili on the bacteria's surface seemed to be primarily for electrical conduction rather than to help them to attach to the anode; mutant forms without pili were still able to stay attached.
Microbial fuel cells can be used in monitoring devices in environments where it is difficult to replace batteries if they fail but to be successful they need to have an efficient and long-lasting source of power. Professor Lovley described how G. sulfurreducens strain KN400 might be used in sensors placed on the ocean floor to monitor migration of turtles.
Society for General Microbiology