الأربعاء، 18 ديسمبر 2013

ScienceDaily: Health & Medicine News

ScienceDaily: Health & Medicine News


An apple a day keeps the doctor away

Posted: 17 Dec 2013 06:05 PM PST

Prescribing an apple a day to all adults aged 50 and over would prevent or delay around 8,500 vascular deaths such as heart attacks and strokes every year in the UK -- similar to giving statins to everyone over 50 years who is not already taking them -- according to a study.

Experts discover whether it's better to be right or be happy

Posted: 17 Dec 2013 06:05 PM PST

Doctors see many couples who lead unnecessarily stressful lives by wanting to be right rather than happy.

Importance of food as key provider of vitamins and nutrients

Posted: 17 Dec 2013 02:08 PM PST

While dietary supplements can help some people meet their nutrition needs, eating a wide variety of nutrient-rich foods is the best way for most people to obtain the nutrients they need to be healthy and reduce their risk of chronic disease, according to the Academy of Nutrition and Dietetics.

Study finds known lung cancer oncogenes also drive colorectal cancer

Posted: 17 Dec 2013 10:40 AM PST

A study shows that ALK and ROS1 gene rearrangements known to drive subsets of lung cancer are also present in some colorectal cancers. These results imply that drugs used to target ALK and ROS1 in lung cancer may also have applications in this subset of colorectal cancer patients.

Changes in proteins may predict ALS progression

Posted: 17 Dec 2013 09:40 AM PST

Measuring changes in certain proteins -- called biomarkers -- in people with amyotrophic lateral sclerosis may better predict the progression of the disease, according to scientists.

Overworked cellular machines may explain Gaucher disease link to Parkinson's disease

Posted: 17 Dec 2013 09:38 AM PST

Research with fruit fly model suggests that Gaucher disease (GD) is related to Parkinson's disease (PD) through biological pathways triggered by accumulated defective proteins related to GD. Accumulation, due to overworked cellular machines responsible for degrading defective proteins, triggers cascade that leads to the death of dopamine-producing cells that causes PD.

Researchers discover mechanism controlling development of myelodysplastic syndromes

Posted: 17 Dec 2013 09:38 AM PST

Researchers have discovered a control mechanism that can trigger the development of myelodysplastic syndromes (MDS), a group of blood cancers. This finding may lead to therapies capable of preventing the progression of these diseases.

Study indicates oral garlic not useful in treating vaginal thrush

Posted: 17 Dec 2013 07:46 AM PST

In a world-first study, researchers have found garlic does not significantly reduce vaginal candida (thrush).

Study: Pay kids to eat fruits, vegetables

Posted: 17 Dec 2013 07:46 AM PST

Researchers observed three schools adjust to new school lunch standards that require a serving of fruits or vegetables on every student's tray -- whether the child intends to eat it or not. Students discarded 70 percent of the extra fruits and vegetables -- wasting about $3.8 million each day.

Fungal pathogen shows profound effects from spaceflight

Posted: 17 Dec 2013 07:45 AM PST

In a new study, the first global gene expression profiling and phenotypic characterization of a fungal pathogen during spaceflight is revealed.

Research backs risk-reduction surgery for ovarian cancer

Posted: 17 Dec 2013 07:42 AM PST

A study backs preventative surgery to improve survival for women who are at greater risk of getting ovarian cancer and suggests it appears helpful for women at risk of getting breast cancer because of genetic faults.

Discovery of 'teen gene' could hold promise for combating severe mental illnesses

Posted: 17 Dec 2013 07:42 AM PST

Researchers have isolated a gene, DCC, which is responsible for dopamine connectivity in the medial prefrontal cortex during adolescence. Working with mice models, they have shown that dysfunction of this gene during adolescence has behavioral consequences which carry into adulthood.

Epidemic of escherichia coli infections traced to one strain of bacteria

Posted: 17 Dec 2013 07:41 AM PST

In the past decade, a single strain of Escherichia coli, or E. coli, has become the main cause of bacterial infections in women and the elderly by invading the bladder and kidneys, according to a new study.

Researchers show genetic overlap in schizophrenia, cognitive ability

Posted: 17 Dec 2013 05:53 AM PST

Investigators have discovered, for the first time, a direct evidence of a genetic overlap between schizophrenia and general cognitive ability.

Pain drugs used in prostate gland removal linked to cancer outcome, study finds

Posted: 17 Dec 2013 05:53 AM PST

The methods used to anesthetize prostate cancer patients and control pain when their prostate glands are surgically removed for adenocarcinoma may affect their long-term cancer outcomes, a study found.

Smoking changes our genes

Posted: 17 Dec 2013 05:52 AM PST

We inherit our genes from our parents at birth. Later in life the genetic material can be changed by epigenetic modifications, i.e. chemical alterations of the DNA the affect the activity of the genes. Such alterations are normally caused by aging, but can also result from environmental factors and lifestyle. New research findings show that smoking alters several genes that can be associated with health problems for smokers, such as increased risk for cancer and diabetes.

Drug residues in Swedish sewage water

Posted: 17 Dec 2013 05:52 AM PST

Chemists in Sweden have been able to trace narcotics substances and prescription drugs in measurements of wastewater from 33 Swedish sewage treatment plants. Cocaine, amphetamine, and methamphetamine, in measurable concentrations, were found in a total of half of the locations.

Self-worth boosts ability to overcome poverty

Posted: 17 Dec 2013 05:50 AM PST

For people in poverty, remembering better times – such as past success – improves brain functioning by several IQ points and increases their willingness to seek help from crucial aid services, a new study finds.

Ear acupuncture can help shed pounds

Posted: 16 Dec 2013 05:40 PM PST

Ear acupuncture can help shed the pounds, indicates a small study, recently published.

Study analyzes diabetes drug metformin as obesity treatment for children

Posted: 16 Dec 2013 03:38 PM PST

Treatment with the diabetes drug metformin appears to be associated with a modest reduction in body mass index in obese children when combined with lifestyle interventions such as diet and exercise.

Antihypertensives associated with lower dialysis risk for patients with advanced CKD

Posted: 16 Dec 2013 03:38 PM PST

Patients with stable hypertension and the most advanced stage of chronic kidney disease before dialysis appeared to have a lower risk for long-term dialysis or death if they were treated with the antihypertensive drugs known as angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, according to a study published.

Physicians who prefer hospice care for themselves more likely to discuss it with patients

Posted: 16 Dec 2013 03:38 PM PST

Although the vast majority of physicians participating in a multiregional study indicated that they would personally enroll in hospice care if they received a terminal cancer diagnosis, less than one-third would discuss hospice care early in the course of treating a terminally ill cancer patient.

Teaching residents to provide cost-conscious care

Posted: 16 Dec 2013 03:38 PM PST

Despite a national consensus among policy makers and educators to train residents to be more conscious of the cost of care, less than 15 percent of internal medicine residency programs have a formal curriculum addressing it.

Regenerative medicine: New tool for transplanting stem cells

Posted: 16 Dec 2013 03:36 PM PST

Researchers have developed a specialized catheter for transplanting stem cells into the beating heart. The novel device includes a curved needle and graded openings along the needle shaft, allowing for increased distribution of cells. The result is maximized retention of stem cells to repair the heart.

Bedtime for toddlers: Timing is everything

Posted: 16 Dec 2013 12:50 PM PST

The bedtime you select for your toddler may be out of sync with his or her internal body clock, which can contribute to difficulties for youngsters attempting to settle in for the night, according to a new study.

Retinoblastoma dysfunction promotes pancreatic cancer cell growth, study shows

Posted: 16 Dec 2013 12:49 PM PST

Cancer researchers have discovered that a protein that normally suppresses tumors actually promotes the growth and spread of pancreatic cancer.

Climate change puts 40% more people at risk of absolute water scarcity, study says

Posted: 16 Dec 2013 12:48 PM PST

Water scarcity impacts people's lives in many countries already today. Future population growth will increase the demand for freshwater even further. Yet in addition to this, on the supply side, water resources will be affected by projected changes in rainfall and evaporation. Climate change due to unabated greenhouse-gas emissions within our century is likely to put 40 percent more people at risk of absolute water scarcity than would be without climate change, a new study shows.

Diversity of antiviral bacteria discovered

Posted: 16 Dec 2013 11:23 AM PST

Wolbachia, a symbiont that resides naturally up to 70% of all insect species, are probably the most prevalent infectious bacteria on Earth. Scientists have discovered that Wolbachia can protect their hosts against viral infections. Since then, several studies have been made to further investigate the interactions between Wolbachia and insects, aiming to build new strategies to use this bacterium in the control of diseases transmitted by mosquitoes, such as dengue.

Health care costs steadily increase with body mass

Posted: 16 Dec 2013 11:22 AM PST

Researchers are giving people another reason to lose weight in the new year: obesity-related illnesses are expensive. According to a study published, health care costs increase in parallel with body mass measurements, even beginning at a recommended healthy weight.

Heavy marijuana users have abnormal brain structure, poor memory

Posted: 16 Dec 2013 05:04 AM PST

Teens who were heavy marijuana users had abnormal changes in their brains related to memory and performed poorly on memory tasks, reports a new study. The brain abnormalities and memory problems were observed in the subjects' early twenties, two years after they stopped smoking marijuana, possibly indicating long-term effects. Memory-related structures in their brains appeared to shrink. The younger drug abuse starts, the more abnormal the brain appeared. The marijuana-related brain abnormalities look similar to schizophrenia-related brain abnormalities.

Lung lesions of TB variable, independent whether infection is active or latent

Posted: 15 Dec 2013 01:09 PM PST

The lung lesions in an individual infected with tuberculosis are surprisingly variable and independent of each other, despite whether the patient has clinically active or latent disease, according to a new animal study. The findings could point the way to new vaccines to prevent the hard-to-treat infection.

Big step for cell reprogramming

Posted: 15 Dec 2013 01:07 PM PST

A group of researchers has discovered a faster and more efficient mechanism for reprogramming induced pluripotent stem cells (iPS). The discovery decreases the time needed for cell reprogramming from a couple of weeks to a few days and reveals new information on the reprogramming process for iPS cells and their potential medical applications.

Call to tighten up value for money appraisals of new drugs in England

Posted: 14 Dec 2013 11:48 AM PST

The body that appraises the clinical and cost effectiveness of new drugs in England would do well to take a leaf out of its sister organizations' books in Wales and Scotland, says an editorial in the Drug and Therapeutics Bulletin.

Significant minority think doctors should help 'tired of living' elderly to die if that's their wish

Posted: 14 Dec 2013 11:48 AM PST

One in five people believes that doctors should be allowed to help the elderly who are not seriously ill, but who are tired of living, to die, if that is their stated wish, reveals research published.

ScienceDaily: Top News

ScienceDaily: Top News


An apple a day keeps the doctor away

Posted: 17 Dec 2013 06:05 PM PST

Prescribing an apple a day to all adults aged 50 and over would prevent or delay around 8,500 vascular deaths such as heart attacks and strokes every year in the UK -- similar to giving statins to everyone over 50 years who is not already taking them -- according to a study.

Experts discover whether it's better to be right or be happy

Posted: 17 Dec 2013 06:05 PM PST

Doctors see many couples who lead unnecessarily stressful lives by wanting to be right rather than happy.

Lower Rio Grande Basin study shows shortfall in future water supply

Posted: 17 Dec 2013 02:10 PM PST

Reclamation released the Lower Rio Grande Basin Study that evaluated the impacts of climate change on water demand and supply imbalances along the Rio Grande from Fort Quitman, Tex., to the Gulf of Mexico. As a result of climate change, a projected 86,438 acre-feet of water per year will need to be added to the 592,084 acre-feet per year of supply shortfall predicted in the existing regional planning process in 2060.

Importance of food as key provider of vitamins and nutrients

Posted: 17 Dec 2013 02:08 PM PST

While dietary supplements can help some people meet their nutrition needs, eating a wide variety of nutrient-rich foods is the best way for most people to obtain the nutrients they need to be healthy and reduce their risk of chronic disease, according to the Academy of Nutrition and Dietetics.

A roly-poly pika gathers much moss: High-fiber salad bar may help lagomorphs survive climate change

Posted: 17 Dec 2013 02:08 PM PST

In some mountain ranges, Earth's warming climate is driving rabbit relatives known as pikas to higher elevations or wiping them out. But biologists discovered that roly-poly pikas living in rockslides near sea level in Oregon can survive hot weather by eating more moss than any other mammal.

DNA motor 'walks' along nanotube, transports tiny particle

Posted: 17 Dec 2013 12:53 PM PST

Researchers have created a new type of molecular motor made of DNA and demonstrated its potential by using it to transport a nanoparticle along the length of a carbon nanotube.

Hack the planet? Geoengineering research, ethics, governance explored

Posted: 17 Dec 2013 12:53 PM PST

Experts have described the proposed Oxford Principles to govern geoengineering research and surveyed the technical hurdles, ethics and regulatory issues related to deliberately manipulating the planet's climate.

Significant advance reported with genetically modified poplar trees

Posted: 17 Dec 2013 10:47 AM PST

Forest geneticists have created genetically modified poplar trees that grow faster, have resistance to insect pests and are able to retain expression of the inserted genes for at least 14 years, a report has just announced.

Exposing the roots of the lithium battery problem

Posted: 17 Dec 2013 10:47 AM PST

Researchers have discovered that the dendrite problem that can cause lithium-ion batteries to short-circuit, overheat and possibly catch fire originates below the surface of the lithium electrode and not at the surface as has been widely believed.

Researchers develop advanced 3D 'force microscope'

Posted: 17 Dec 2013 10:47 AM PST

Researchers have developed a three-dimensional microscope that will yield unparalleled study of membrane proteins and how they interact on the cellular level. These microscopes could help pharmaceutical companies bring drugs to market faster.

Rainforest rodents risk their lives to eat

Posted: 17 Dec 2013 09:40 AM PST

Hungry rodents that wake up early are much more likely to be eaten by ocelots than rodents getting plenty of food and shut-eye, according to new results.

Home-making post-disaster

Posted: 17 Dec 2013 09:40 AM PST

When it comes time to rebuild, victims of home-destruction are often given only the bare essentials and told to make do. That is nowhere near enough says recent Concordia University doctoral graduate, Devora Neumark. In a new paper published in Housing, Theory and Society she argues that a powerful way to overcome the traumas associated with domicide and reconstitute a sense of home is to engage in house-beautification practices.

Never forget a face: New algorithm uses subtle changes to make a face more memorable without changing a person's overall appearance

Posted: 17 Dec 2013 09:39 AM PST

A new algorithm uses subtle changes to make a face more memorable without changing a person's overall appearance.

Targeted synthesis of natural products with light

Posted: 17 Dec 2013 09:39 AM PST

Photoreactions are essential for the syntheses of many natural substances. Since many of these substances are also useful as active medical agents, chemists try to produce them synthetically. But in most cases only one of the possible products has the right spatial structure to make it effective. Researchers have now developed a methodology for one of these photoreactions that allows them to produce only the specific molecular variant desired.

Economically valuable sweet-gum trees: Taxonomy and nine new combinations

Posted: 17 Dec 2013 09:39 AM PST

Trees in the sweet-gum family Altingiaceae are well-known for their quality timber, use as ornamentals, the source of styrax, and from Chinese medicine. The three previously recognized genera Liquidambar, Altingia and Semiliquidambar have been puzzling botanists for a while due to the morphological similarities between the different genera, which makes their separation and description a challenge. A new taxonomic synopsis provides a new analysis including nine new combinations.

Uranium (IV) found to be mobile in a natural wetland

Posted: 17 Dec 2013 09:39 AM PST

Researchers studying a natural wetland near a decommissioned uranium mine in Limousin, France, have shown that under certain circumstances the uranium present in the wetland could be more mobile than previously believed.

Bonobos stay young longer: Unlike humans and chimpanzees, bonobos retain elevated thyroid hormones well into adulthood

Posted: 17 Dec 2013 09:38 AM PST

Despite the fact that chimpanzees and bonobos share similar starting conditions at birth, they develop different behavioral patterns later in life. These differences might be caused by different hormone levels.

Researchers discover mechanism controlling development of myelodysplastic syndromes

Posted: 17 Dec 2013 09:38 AM PST

Researchers have discovered a control mechanism that can trigger the development of myelodysplastic syndromes (MDS), a group of blood cancers. This finding may lead to therapies capable of preventing the progression of these diseases.

Study indicates oral garlic not useful in treating vaginal thrush

Posted: 17 Dec 2013 07:46 AM PST

In a world-first study, researchers have found garlic does not significantly reduce vaginal candida (thrush).

Study: Pay kids to eat fruits, vegetables

Posted: 17 Dec 2013 07:46 AM PST

Researchers observed three schools adjust to new school lunch standards that require a serving of fruits or vegetables on every student's tray -- whether the child intends to eat it or not. Students discarded 70 percent of the extra fruits and vegetables -- wasting about $3.8 million each day.

Fungal pathogen shows profound effects from spaceflight

Posted: 17 Dec 2013 07:45 AM PST

In a new study, the first global gene expression profiling and phenotypic characterization of a fungal pathogen during spaceflight is revealed.

Sharpening focus in quantum photolithography

Posted: 17 Dec 2013 07:44 AM PST

Photolithography uses light beams to design thin geometric patterns on the substrates of semiconductors used in microelectronic devices. This is achieved using a chemical reaction on a light-sensitive chemical, called photoresist. The trouble is that the phenomenon of light diffraction does not permit highly accurate patterns. Now, a scientist has developed a quantum lithography protocol designed to improve the resolution of this technology.

Brain neurons subtract images, use differences

Posted: 17 Dec 2013 07:42 AM PST

Ten million bits -- that's the information volume transmitted every second with every quick eye movement from the eye to the cerebrum. Researchers describe the way those data are processed by the primary visual cortex, the entry point for the visual information into the brain. Deploying novel optical imaging methods, they demonstrated that the brain does not always transmit the entire image information. Rather, it uses the differences between current and previously viewed images.

Research backs risk-reduction surgery for ovarian cancer

Posted: 17 Dec 2013 07:42 AM PST

A study backs preventative surgery to improve survival for women who are at greater risk of getting ovarian cancer and suggests it appears helpful for women at risk of getting breast cancer because of genetic faults.

Infrared sheds light on single protein complexes

Posted: 17 Dec 2013 07:42 AM PST

Nanoscience researchers employ nano-FTIR spectroscopy for label-free chemical and structural imaging of proteins with nanoscale spatial resolution and with sensitivity to single protein complexes of less than one attogram (10-18 gram), and discuss these results in a recently published article.

Radioactivity muddles alphabet of DNA

Posted: 17 Dec 2013 07:42 AM PST

Researchers have shown natural radioactivity within DNA can alter chemical compounds, providing a new pathway for genetic mutation. The research for the first time looked at natural radioactivity within human DNA on the atomic-scale. While radioactivity occurs naturally in our bodies as well as in every living organism across the planet, it was never before thought to affect our DNA in such a direct way.

Discovery of 'teen gene' could hold promise for combating severe mental illnesses

Posted: 17 Dec 2013 07:42 AM PST

Researchers have isolated a gene, DCC, which is responsible for dopamine connectivity in the medial prefrontal cortex during adolescence. Working with mice models, they have shown that dysfunction of this gene during adolescence has behavioral consequences which carry into adulthood.

Epidemic of escherichia coli infections traced to one strain of bacteria

Posted: 17 Dec 2013 07:41 AM PST

In the past decade, a single strain of Escherichia coli, or E. coli, has become the main cause of bacterial infections in women and the elderly by invading the bladder and kidneys, according to a new study.

Hubble watches super star create holiday light show

Posted: 17 Dec 2013 07:40 AM PST

This festive NASA Hubble Space Telescope image resembles a holiday wreath made of sparkling lights. The bright southern hemisphere star RS Puppis, at the center of the image, is swaddled in a gossamer cocoon of reflective dust illuminated by the glittering star. Hubble took a series of photos of light flashes rippling across the nebula in a phenomenon known as a "light echo."

Researchers show genetic overlap in schizophrenia, cognitive ability

Posted: 17 Dec 2013 05:53 AM PST

Investigators have discovered, for the first time, a direct evidence of a genetic overlap between schizophrenia and general cognitive ability.

Pain drugs used in prostate gland removal linked to cancer outcome, study finds

Posted: 17 Dec 2013 05:53 AM PST

The methods used to anesthetize prostate cancer patients and control pain when their prostate glands are surgically removed for adenocarcinoma may affect their long-term cancer outcomes, a study found.

Smoking changes our genes

Posted: 17 Dec 2013 05:52 AM PST

We inherit our genes from our parents at birth. Later in life the genetic material can be changed by epigenetic modifications, i.e. chemical alterations of the DNA the affect the activity of the genes. Such alterations are normally caused by aging, but can also result from environmental factors and lifestyle. New research findings show that smoking alters several genes that can be associated with health problems for smokers, such as increased risk for cancer and diabetes.

New control pathways in synthesis of plant chemical defences

Posted: 17 Dec 2013 05:52 AM PST

A scientific study reveals a new mechanism to control saponin biosynthesis. Saponins are essential in the adaptation of many plants to the environment and have high biomedical and industrial interest.

Infrared sheds light on single protein complexes

Posted: 17 Dec 2013 05:51 AM PST

Researchers have used spectroscopy for label-free chemical and structural imaging of proteins with nanoscale spatial resolution and with sensitivity to single protein complexes of less than one attogram (10-18 gram).

Self-worth boosts ability to overcome poverty

Posted: 17 Dec 2013 05:50 AM PST

For people in poverty, remembering better times – such as past success – improves brain functioning by several IQ points and increases their willingness to seek help from crucial aid services, a new study finds.

Massive stars mark out Milky Way's 'missing arms'

Posted: 17 Dec 2013 05:50 AM PST

A 12-year study of massive stars has reaffirmed that our Galaxy has four spiral arms, following years of debate sparked by images taken by NASA's Spitzer Space Telescope that only showed two arms.

Ancestor of snakes, lizards likely gave birth to live young

Posted: 17 Dec 2013 05:49 AM PST

The ancestor of snakes and lizards likely gave birth to live young, rather than laid eggs, and over time species have switched back and forth in their preferred reproductive mode, according to new research.

Ear acupuncture can help shed pounds

Posted: 16 Dec 2013 05:40 PM PST

Ear acupuncture can help shed the pounds, indicates a small study, recently published.

Teaching residents to provide cost-conscious care

Posted: 16 Dec 2013 03:38 PM PST

Despite a national consensus among policy makers and educators to train residents to be more conscious of the cost of care, less than 15 percent of internal medicine residency programs have a formal curriculum addressing it.

Regenerative medicine: New tool for transplanting stem cells

Posted: 16 Dec 2013 03:36 PM PST

Researchers have developed a specialized catheter for transplanting stem cells into the beating heart. The novel device includes a curved needle and graded openings along the needle shaft, allowing for increased distribution of cells. The result is maximized retention of stem cells to repair the heart.

Loggerhead sea turtle nesting activity driven by recent climate conditions

Posted: 16 Dec 2013 12:50 PM PST

New research indicates that for loggerhead sea turtles in the Northwest Atlantic, the number of returning nesting females in the population and favorable climate conditions in the year or two prior to the nesting year are strongly related to the number of nests produced by these animals in a given year. Also, in what may be good news for loggerheads, nesting increases since 2008 may be a recovery response in this threatened population.

Retinoblastoma dysfunction promotes pancreatic cancer cell growth, study shows

Posted: 16 Dec 2013 12:49 PM PST

Cancer researchers have discovered that a protein that normally suppresses tumors actually promotes the growth and spread of pancreatic cancer.

New global study reveals how diet and digestion in cows, chickens and pigs drives climate change 'hoofprint'

Posted: 16 Dec 2013 12:49 PM PST

The resources required to raise livestock and the impacts of farm animals on environments vary dramatically depending on the animal, the type of food it provides, the kind of feed it consumes and where it lives, according to a new study that offers the most detailed portrait to date of "livestock ecosystems" in different parts of the world.

Climate change puts 40% more people at risk of absolute water scarcity, study says

Posted: 16 Dec 2013 12:48 PM PST

Water scarcity impacts people's lives in many countries already today. Future population growth will increase the demand for freshwater even further. Yet in addition to this, on the supply side, water resources will be affected by projected changes in rainfall and evaporation. Climate change due to unabated greenhouse-gas emissions within our century is likely to put 40 percent more people at risk of absolute water scarcity than would be without climate change, a new study shows.

Assessing the impact of climate change on a global scale

Posted: 16 Dec 2013 12:44 PM PST

Thirty research teams in 12 different countries have systematically compared state-of-the-art computer simulations of climate change impact to assess how climate change might influence global drought, water scarcity and river flooding in the future.

Drought and climate change: an uncertain future?

Posted: 16 Dec 2013 12:44 PM PST

Drought frequency may increase by more than 20% in some regions of the globe by the end of the 21st century, but it is difficult to be more precise as we don't know yet how changes in climate will impact on the world's rivers.