Tuesday, 22 May 2007

Viagra helps hamsters overcome jet lag

A hamster-size dose of sildenafil, more commonly known by its marketing name Viagra, helps the rodent recover more quickly from a six-hour advance in its daily cycle, researchers report.

Originally developed for the treatment of high blood pressure and angina, Sildenafil works by interfering with an enzyme that reduces levels of a naturally-occurring compound, cyclic guanine monophosphate (cGMP). In the brain, cGMP has an important function in a signalling pathway that regulates the body’s daily clock.

Biotechnologist Patricia Agostino and colleagues at the Universidad Nacional de Quilmes in Argentina injected hamsters with sildenafil at night, before turning on bright lights six hours earlier than natural sunrise. The team then observed how the hamsters adjusted to the change, by noting how soon they began running in their exercise wheels.

Sildenafil-boosted hamsters recovered from the jet lag up to 50 percent more quickly than unassisted animals. However, the drug only worked when applied before an advance in the light/dark cycle, equivalent to an eastbound flight, rather than the reverse.

The scientists believe that frequent flyers and shift workers could benefit from moderate doses of sildenafil.

The study will be published in the U.S. journal, PNAS, this week.


Monday, 21 May 2007

Do fruit flies have free will?

In scientific spheres, insects have a reputation similar to that of complex robots that respond predictably to their surroundings. However, a new study has claimed that fruit flies might not be as simple as previously believed, and could actually exhibit free will.

The concept of free will has been a topic of debate, even in relation to humans. Some scientists believe that the purpose of human consciousness is merely to rationalise every decision made by chemical processes in the brain a few milliseconds after the fact. Others believe that once enough is known about the human brain, it will be possible to explain and even predict a person’s behaviour.

"Given this strong claim for humans, it is surprising if prediction should be principally impossible in flies," said Björn Brembs, a biologist from the Free University Berlin and senior author of the fruit fly study. "[But] our work shows that for flies such a prediction will not be possible to the extent claimed."

Together with an international team of researchers, Brembs tethered fruit flies in completely uniform white surroundings and recorded their turning behaviour. In this setup, the flies do not receive any visual cues from the environment, and since they are fixed in space, their turning attempts have no effect.

Without any external stimuli from their surroundings, the scientists expected the flies’ behaviour to resemble random noise, similar to a radio tuned between stations. However, researchers observed the flies behaving non-randomly.

The researchers then tested a plethora of increasingly complex random computer models, all of which failed to adequately model fly behaviour, leading to the conclusion that variability in fruit fly behaviour is not due to simple random events, but is generated spontaneously and non-randomly by the brain.

Björn Brembs came up with the idea to study spontaneous behaviour almost 10 years ago in 1998, as part of his work on operant conditioning. However, as he lacked the tools required to conduct experiments, the study was put on hold until late 2004, when discussions with colleague Mark Frye sparked his interest in fruit flies.

As a biologist, Brembs is interested in the biological aspects that might enable or prevent the existence of free will. While he believes that absolute freedom is impossible, Brembs questions the extent to which humans and animals are free, and expects this to be where the species differ.
"Scientifically, the most important aspect is that we found evidence for a brain function which appears evolutionarily designed to always spontaneously vary ongoing behaviour," Brembs explained.

"There is tentative evidence that such a function may be very widespread in the animal kingdom, including humans. If this were indeed the case, we might
have discovered the first evidence for something truly fundamental," he said.

The next step will be to use genetics to localize and understand the brain circuits responsible for the spontaneous behaviour. This step could lead directly to the development of robots with the capacity for spontaneous non-random behaviour and may help combating disorders leading to compromised spontaneous behavioural variability in humans such as depression, schizophrenia or obsessive compulsive disorder.


Saturday, 19 May 2007

King Herod's tomb discovered

Thousands of years after his death, the King of Judea has returned.

Once ruler of Jerusalem in the first century, King Herod the Great has risen to the forefront of public discussion in the twenty first century.

After many years of archaeological searches, Herod’s tomb was finally found at the site of what is possibly his most outstanding construction, Herodium. The discovery was made when pieces of the desecrated limestone sarcophagus were found by archaeologists.

The dig that led to the discovery was headed by Hebrew University Professor Ehud Netzer, an expert on King Herod who has been working at the site since 1972.

Netzer has said there is no doubt this recent find is the burial site of King Herod, when the historical records and the nature and location of the findings are considered.

Researchers have believed Herodium to be the site of the ancient King’s tomb for many years, based upon the writings of ancient Jewish historian Flavius Josephus. This excavation focused on an area not yet searched.

About 12km south of Jerusalem in the Judean Desert in the West Bank, the recently uncovered tomb site is where it has long been thought and recorded as residing. Mount Herodium is a flattened hilltop between Bethlehem and Masada where Herod constructed a great palace, fortress and monument.

The complex Herod built at Mount Herodium served many purposes, including a residential palace, a sanctuary, a mausoleum and an administrative center. He also built a second palace at the base of the hill, known as ‘Lower Herodium’. The palace included many buildings, pools, gardens, stables, and was the size of a small town.

Renowned for his building projects, in particular the expansion of the second Jewish temple, Mount Moriah, Herodium is Herod’s only project that is also his namesake and is the place he chose to be buried and memorialised.

Herod was a Roman appointed King and therefore faced opposition by Jewish rebels, who are suspected to have destroyed his sarcophagus and stolen his remains during their rebellion against Rome after his death. He reigned from 37-4BCE, at his death.

Herod is also famous in the Christian tradition, which represents him as an evil King who ordered the death of all Jewish baby boys out of fear of a prophetic claim that he would be superseded as King by the birth of baby Jesus.

This find has been described as one the most striking discoveries in Israel in recent years by archaeologists involved in the successful search and has sparked worldwide interest.

Kathryn Loughman is a student and freelance journalist in Sydney, Australia.


Wednesday, 16 May 2007

Curbing deforestation could stop climate change - if it exists

The effect of human activities on climate change is real, according to a new study on tropical deforestation in areas like the Amazon and Indonesia.

Conducted by an international team of researchers from the U.S., U.K., Brazil, France and Australia, the study claims to have confirmed that avoiding deforestation can play a key role in reducing future greenhouse gas concentrations.

Nearly 20 percent of carbon emissions is said to be contributed by deforestation in the tropics. This equates to about 1.5 billion tonnes of carbon each year, adding up to an estimated 130 billion tonnes of carbon by the year 2100.

"[The 2100 projection] is greater than the amount of carbon that would be released by 13 years of global fossil fuel combustion," said CSIRO atmospheric scientist Pep Canadall, who is also a researcher on the Global Carbon Project and on the deforestation study.

"Maintaining forests as carbon sinks will make a significant contribution to stabilising atmospheric greenhouse gas concentrations," he said. "The new body of information … also demonstrates the need to avoid higher levels of global warming, which could slow the ability of forests to accumulate carbon."

"Climate changes all the time, so if the goal is to keep it constant, or 'sustainable', it is a hopeless task"
- Bjarne Andresen
According to thermodynamics expert Bjarne Andresen, however, the very concept of global warming could be a farce. A professor of physics at the esteemed Niels Bohr Institute in Denmark, Andresen's recent report in the international Journal of Non-Equilibrium Thermodynamics claims that the notion of an overall global temperature is both a thermodynamical and mathematical impossibility.

Explaining 'temperature' as a comparative quantity that can only have meaning at a point or for a homogeneous system, Andresen argued that Earth consists of a huge number of components. Adding temperatures together to form a global average would have the same, meaningless effect as calculating the average phone number in a telephone directory, he said.

"The whole idea of global anything is a figment of the imagination," he said. "Effects happen locally and will be different at different spots on Earth; some places will heat up, others cool down."

"Climate changes all the time, so if the goal is to keep it constant, [or] 'sustainable', it is a hopeless task," he said, although stressing that the futility of a constant climate is his personal opinion, and not part of his scientific work.

While he is also of the opinion that humans are ethically obliged not to pollute the environment with poisonous substances like PCB and mercury, Andresen questioned the purpose of using wood, which has sometimes been touted as renewable energy source, instead of coal.

"What is the big difference between the so-called renewable energy source wood as opposed to coal?" he said. "Coal used to be wood as well, so we are actually just burning old wood. In both cases the carbon originally came from the atmosphere and we are returning it there."

Andresen urged climatologists to rethink their methods of analysing climate, as 'equally correct' methods of averaging could each yield wildly different conclusions about the state of the environment.

Emphasising that strong physical arguments are needed to decide on which averaging method to use in describing the climate, Andresen argued that currently approaches to 'global warming' could be employing more of a political, fear-mongering tactic than a scientific approach to the issue.

Atmospheric physicist Michael Box, of the University of New South Wales, defended the averaging methods currently favoured by many climatologists, saying that while 'average temperature' may be a term used loosely by policy makers, 'real' climate scientists use a vast range of inputs as best they can.

"I'm sure all atmospheric physicists know that you can't average temperatures in a strictly formal sense," he said. "However, it is a piece of data that we have going back for a century, so we have something we can compare to."

"We all know that it is temperature gradients which drive the atmosphere - i.e. meteorology," he said. "Nevertheless, an increase in global average temperature is a clear sign that something is going on!"


Thursday, 10 May 2007

Electronic babysitters raise a generation of TV devotees

Just under half of 3-month-old infants are regular viewers of TV, DVDs or videos, a recent survey has found. By the age of two, researchers say, 90 percent of children would have become devotees of the idiot box.

Conducted in the U.S. by researchers at the University of Washington (UW) and Seattle Children’s Hospital Research Institute, the study has been touted as the first to investigate the media diet of infants who are too young to speak for themselves.

Through random telephone surveys of more than 1,000 families with children under the age of two in the U.S. states of Minnesota and Washington, researchers found the median age at which infants were regularly exposed to media was 9 months.

Among those who watched TV, DVDs or videos, the average daily viewing time jumped from 60 minutes per day for those children younger than one year to more than 90 minutes a day by two years.

"Early television viewing has exploded in recent years, and is one of the major public health issues facing American children," said Frederick Zimmerman, lead author of the study and a UW professor of health services.

"Exposure to TV takes time away from more developmentally appropriate activities such as a parent or adult caregiver and an infant engaging in free play with dolls, blocks or cars," he said.

A majority of parents cited a belief in the educational properties of media as a reason for permitting their children to watch TV, while others believed viewing to be enjoyable or relaxing for the child. About one fifth of parents surveyed admitted to using electronic media as a babysitter, so they could focus on other chores.

While Zimmerman agreed that appropriate television viewing can be helpful for both children and parents, he warned that excessive viewing before the age of three has been shown to be related to attention problems, aggressive behaviour, and poor cognitive development.

Developmental psychologist Andrew Meltzoff, a co-author of the study and co-director of the UW’s Instutute for Learning and Brain Sciences said: "Most parents seek what's best for their child, and we discovered that many parents believe that they are providing educational and brain development opportunities by exposing their babies to 10 to 20 hours of viewing per week."

"We need more research on both the positive and negative effects of a steady diet of baby TV and DVD viewing," he said, "but parents should feel confident that high-quality social interaction with babies, including reading and talking with them, provides all the stimulation that the growing brain needs."

More information is available from the University of Washington’s press release.


Monday, 7 May 2007

Study explains interpersonal barriers in autism

Facial expressions are normally thought to have a significant role in face-to-face communication, giving context and meaning to the words we hear. While most people take the ability to evaluate visual cues for granted, however, a new report has found autistic children lacking in the brain function to discern between a smile and a frown.

Researchers at the University of California, Los Angeles, studied the brain activity of 16 typically developing children and 16 high-functioning children with autism to determine their responses to faces depicting angry, fearful, happy and neutral expressions.

When children in the typically developing group were shown faces with either a direct or indirect gaze, the researchers found significant differences in activity in a part of the brain called the ventrolateral prefrontal cortex (VLPFC), which is known to play a role in evaluating emotions.

In contrast, the autistic children showed no activity in this region of the brain whether they were looking at faces with a direct or an indirect gaze.

"This part of the brain helps us discern the meaning and significance of what another person is thinking," said lead researcher Mari Davies, a graduate student in psychology. "Gaze has a huge impact on our brains because it conveys part of the meaning of that expression to the individual. It cues the individual to what is significant."

The results are said to explain why children diagnosed with autism have varying degrees of impairment in communication skills and social interactions and display restricted, repetitive and stereotyped patterns of behaviour.

"They don’t pick up what’s going on — they miss the nuances, the body language and facial expressions and sometimes miss the big picture and instead focus on minor, less socially relevant details," Davies said. "That, in turn, affects interpersonal bonds."

More information is available from the University of California’s press release.


Wednesday, 2 May 2007

Alcohol: friend or foe?

It is no secret that Australians like to keep in high spirits. Of course, beer and wine are popular too.

Recently released statistics on drug use found the average Australian to have consumed 92 litres of beer, 20 litres of wine, and 1 litre of pure alcohol from spirits in 2004 alone. About 35 percent of drinkers were found to consume ‘risky’ levels of alcohol, the abuse of which has been blamed for more than a quarter of all deaths of 15 to 29 year-olds in developed countries.

According to biotechnologists from the University of Granada in Spain, however, melatonin found in red wine could delay the oxidative damage and inflammatory processes typical of old age. Though laboratory tests with mice, scientists speculate that daily melatonin intake in humans from the age of 30 or 40 could delay illnesses related to aging, thus promoting longevity.

While exploring ways to keep berries fresh during storage, researchers at the Kasetsart University in Thailand have discovered health benefits in treating the fruit with alcohol. Besides helping berries resist decay, alcohol was found to increase antioxidant capacity within strawberries, and could also increasing their ability to prevent diseases ranging from cancer to neurodegenerative disorders.

Strawberry daiquiri, anyone?