Day: 01/03/2012

Tracking the magnetic south pole.

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Return to Scott’s Antarctic camp marks 100-year anniversary.

Two scientists from New Zealand will travel to Antarctica today in a quest to continue a 100-year-long record of Earth’s magnetic field: a record begun by British explorer Robert Scott at the start of his ill-fated expedition to the geographic south pole .

Record-keeping is necessary because the magnetic poles move about, thanks to the complex circulation of Earth’s fluid outer core. During the past century, both magnetic poles have been moving northwest: the north pole from Canada towards Siberia, as fast as 60 kilometres per year, and the south pole towards Australia at 10–15 km per year. “It’s quite an astonishing rate,” says Stewart Bennie of GNS Science in Avalon, one of the two scientists due to head to the Antarctic on 28 December. The movement is thought to be a normal feature of the planet’s magnetic wobble, and could change direction at any time.

Precise ground measurements of Earth’s magnetic field are used to help calibrate satellite measurements and inform global models, such as the World Magnetic Model, which is used by the North Atlantic Treaty Organization and national departments of defence. That model is updated every 5 years, with the current version covering 2010–14.

There are more than 100 observatories around the globe taking such measurements on a regular basis, and nations supplement these with occasional field work — New Zealand has taken its measurements at Scott’s hut once every 5 years or so since 1957. Hundred-year records are not in themselves unusual, but the location of this one is. “Most records longer than that are sitting somewhere comfortable in Europe,” notes Tony Hurst, the second scientist on the trip.

Rocky outposts

Hurst and Bennie will take measurements at two sites, the first at Lake Vanda in Antarctica’s dry valleys, where it almost never snows. “It’s very startling scenery — there’s no soil, just solid rock and stones, and mummified seals that must have turned right instead of left at the coast,” says Hurst, who went on the same trip 6 years ago. They’ll then visit Cape Evans, where Scott’s hut and iron-free observation shelter still stand. “The observation shelter is made of something we suspect is asbestos but we’re not going to touch it to find out,” says Hurst. Both sites are located on dry rock; ice-bound stations would move too much to allow for repeat observations.

At each site, the duo will align their instruments using geographical features (a compass can’t be used because the magnetic field it would follow is the very thing they are measuring). A magnetic theodolite will allow them to measure the angle of the magnetic field both parallel and perpendicular to the ground; the latter measurement, called the dip, is 90 degrees at the pole itself, where magnetic field lines dive straight into the ground. The researchers will also use an Overhouser effect magnetometer to measure the strength of the magnetic field. The planet’s field has been declining since the 1800s, perhaps by chance, perhaps as a precursor to a ‘flip’ of the poles thousands of years from now.

Making a full set of measurements takes about an hour, says Bennie, but they’ll make continual measurements throughout the day because the field wobbles a tiny amount owing to Earth’s rotation and the effect of the Sun. “We probably should be making these measurements in the Antarctic winter, when the magnetic field would be quieter. But it’s a lot nicer in the summer,” says Bennie.

It will be Bennie’s first trip to the Antarctic, an adventure he is hesitantly looking forward to. “I’ve never been a big fan of really cold weather,” he admits.

Satellites would provide an easier way to make such observations, but only a few are capable of doing so: the German CHAMP satellite collected data from 2000 until 2010, and the Danish Ørsted satellite, launched in 1999, is still working. A European trio of satellites, called Swarm, is due to launch in 2012.

“The challenge with satellite-based maps is to produce something that’s relevant at the surface. Satellites are in or above the ionosphere,” notes Jeffrey Love, a US Geological Survey adviser for geomagnetic research in Denver, Colorado. Hurst says he has been told that ground measurements will become more, not less important, as they will be needed to calibrate the satellite devices.

Source:Nature.

 

 

 

 

Chemist faces criminal charges after researcher’s death.

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UCLA scientist charged three years after lab fire fatality.

Three years after a young chemistry researcher died following a lab fire at the University of California, Los Angeles (UCLA), her supervisor, the organic chemist Patrick Harran, and the University of California now both face criminal charges. Health and safety experts think that it is the first instance of criminal prosecution over an accident in a US academic laboratory.

On 27 December, the Los Angeles District Attorney charged Harran and the regents of the UC system with three counts each of “willful violation of an occupational health and safety standard causing the death of an employee”. An arrest warrant has been issued for Harran, whose lawyer told the LA Times that he will surrender to authorities. He faces up to 4.5 years in prison if convicted, an attorney spokesperson told the paper, while UCLA could be fined up to $1.5 million on each count. In a statement, UCLA said it “intends to mount a vigorous defense against the outrageous charges”.

The death of 23-year-old Sheharbano Sangji has already led to fines of around $70,000 for UCLA, which has also toughened its safety policies. On 29 December 2008, Sangji was using a syringe to draw the reactive t-butyl lithium from a bottle when the pyrophoric liquid burst into flames, setting her clothes alight. She was not wearing a lab coat, suffered third-degree burns, and died in hospital 18 days later. The accident triggered calls to improve academia’s safety standards not just at UCLA, but across the United States. But as Nature discussed in an article on laboratory safety after Yale undergraduate Michele Dufault died in April 2011, there’s little evidence that Sangji’s death has shifted the behaviour of bench scientists or laboratory heads, outside of UCLA.

The LA District Attorney’s legal action could shake up that attitude. “I think this is a game-changer. It will significantly affect how people think about their responsibilities now that it’s clear there’s the possibility of going to jail,” says Jim Kaufman, president of the Laboratory Safety Institute in Natick, Massachusetts.

Concerns surrounding prosecution have been a powerful incentive for change in the United Kingdom, where around 25 years ago Sussex University, in Brighton, was prosecuted for negligence after an explosion in a chemistry laboratory shot a piece of metal into a student’s abdomen. (The student later recovered). Tom Welton, a chemist at Imperial College London, told Nature that the episode had a profound effect on safety standards in Britain.

UCLA’s statement notes that an earlier investigation by the California Division of Occupational Safety and Health (which led to fines) found “no wilful violations on the part of UCLA”. The university called the district attorney’s decision to press charges yesterday “truly baffling”; “the facts provide absolutely no basis for the appalling allegation of criminal conduct,” it said. UCLA would not comment beyond its statement.

Russ Phifer, former head of the American Chemical Society’s safety division and now executive director of the National Registry of Certified Chemists, thinks this is the first instance of criminal prosecution for an academic laboratory accident in the United States. ’I don’t think the University of California or Harran have anything to gain by going to trial,’ he says; in his opinion, the case will be settled before trial with an agreement involving significant amounts of community service, such as talking to other lab heads about the case and chemical safety.

Phifer also thinks that Sangji’s death has already provided a wake-up call for university laboratory safety, with this week’s charges just a new chapter in the story. But Paul Bracher, a chemist at the California Institute of Technology who blogs at ChemBark, notes: “one wonders if this is the shot in the arm that finally forces academia to take safety seriously”.

Source:Nature.

 

 

 

 

Taking the pulse of a shrinking glacier.

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Scientists in Chile hike over plains of snow to recover valuable data.

The Exploradores Glacier in southern Chile is riven with cracks that form vertical cliffs of luminescent blue and indigo ice. A constant sound of running water rises from the rivers snaking beneath the 20-kilometre-long frozen mass that sweeps down from Mount San Valentín. The scene is stunning. And it is also, slowly but surely, disappearing.

To understand why this is happening, scientists must measure the various processes that affect glaciers — not an easy task in this frozen wilderness. Installing and maintaining satellite or radio transmission stations to send back data from this remote region is considered too costly, so Chilean researchers must gather the valuable data in person.

Takane Matsumoto, a glaciologist at the Centre for Ecosystem Research in Patagonia (CIEP), based in Coyhaique, Chile, journeys once a year to the Northern Patagonian Ice Field to check on the health of the Exploradores glacier. He gathers information about temperature, precipitation, humidity and wind speed from monitoring stations that he and Chile’s General Water Directorate have installed.

Matsumoto is trying to understand how weather conditions affect the rate at which the Exploradores Glacier melts, and how the water released flows through and out of the bottom of the glacier. His work is part of a bigger puzzle that researchers around the world are trying to solve: how quickly are glaciers disappearing, and how will that affect local water resources.

“Since my student days, I have been interested in the water flow and melting process of glaciers in humid climates such as Patagonia,” says Matsumoto.

About 75% of the world’s freshwater reserves are locked up in glaciers and ice sheets. The Patagonian Ice Fields, covering about 14,000 square kilometres, are the world’s third-largest frozen landmass after the continental glaciers of Antarctica and Greenland. About 100 glaciers in Chile are being monitored, and Chile’s Centre for Scientific Studies (CECS) in Valdivia says that almost 90% are in retreat.

Earlier this year, glaciologist Neil Glasser of Aberystwyth University, UK, and colleagues estimated that since 1870 the Northern Patagonian Icefield has lost more than 100 cubic kilometres of ice, and that the Southern Patagonian Icefield had lost more than 500 cubic kilometres since 1650. In both case, the melt rate had speeded up considerably in recent decades1.

The San Rafael Glacier, for example, about 55 kilometres southwest of Exploradores, has retreated 12 kilometres over the past 136 years, and is still shrinking. And earlier this month, scientists from the CECS released time-lapse photos showing that the Jorge Montt glacier in the Southern Patagonian Ice Field retreated by about one kilometre between February 2010 and January 2011.

Matsumoto’s journey to the Exploradores Glacier — one of the most accessible of Chile’s glaciers — involves a six-hour drive from Coyhaique to a small shelter about one kilometre from the glacier. Then follows an hour’s walk through evergreen forests and over the moraine of rubble at the foot of the glacier. Eventually, the sliding soil and rock gives way to the ice of the glacier itself.

Over the course of the day he downloads data from monitoring stations on to his laptop. One station records precipitation; another, lying in the glacier’s outlet stream, known locally as the Deshielo River, records data about its melt water. The information about these “plains of snow”, as the region’s original settlers called them, “will help to understand the dynamics of the glacier and, by extension, how it responds to climate change”, says Matsumoto.

Matsumoto will return next year – when he fears the Exploradores may have retreated further still.

Source:Nature.

 

 

Citizen scientists’ climate-impact survey wraps up.

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Forest-monitoring project has measured 150,000 trees and provided researchers with reams of data.

One of the biggest citizen-science projects ever conducted concludes this monthafter five years of data collection. The wealth of information gathered will help researchers to understand how climate change is affecting forests.

The effort has been coordinated by Earthwatch, an environmental group and a member of the HSBC Climate Partnership, which supports a range of environmental projects funded by the international bank. Earthwatch aimed to improve the way that temperate and tropical forests are monitored in countries such as Brazil, China and India, in order to better understand the way that forests capture and release carbon, one of the least understood aspects of the global carbon cycle. Earthwatch has recruited more than 2,200 volunteers (all HSBC employees) to measure tree growth, study the decomposition of leaf litter on the forest floor and analyse soil samples to estimate how much carbon is captured.

“Forests play a huge role in regulating climates at global scale and provide livelihoods for many millions of people, so understanding how they are going to change and adapt to changing conditions is one of the most pressing environmental questions of our time,” says Robert Ewers, a forest biodiversity researcher at Imperial College London who is not involved in the Earthwatch project. “Every forest is different, so well-managed and quality-controlled citizen science such as Earthwatch’s programme represents a powerful way of gaining the large volumes of data that are needed to gain insight into the global patterns of forest change.”

Researchers are only just beginning to analyse data from the project. But some studies, such as that in Gutianshan National Nature Reserve in Zhejiang Province, China, have already confirmed that plantations can be a haven for biodiversity. “The number of tree species in some of the plantation forest plots approaches that of the primary forest,” says Dan Bebber, head of climate-change research at Earthwatch. He says that this proves the value of protecting such secondary forests, as well as pristine forests.

Many of the world’s forests are valuable sources of food or income for indigenous people. A survey of 12 one-hectare plots across a rainfall gradient that runs through evergreen and deciduous forests in the Indian state of Karnataka found a high density of trees producing ‘non-timber forest products’, such as medicine and food. Results from the survey published earlier this year1 show that about one-third of such forests are vulnerable to climate change.

This has serious implications for the local economy, because most of the region’s 1.2 million inhabitants rely on the forests for their income, says forestry expert N. H. Ravindranath, who led the project with Earthwatch and is based at the Centre for Sustainable Technologies, part of the Indian Institute of Science in Bangalore. Bebber adds that data from the project “have been crucial in framing the Indian government’s response to climate change”.

Bebber, who joined Earthwatch to head the climate project, is a once-sceptical convert to the idea of citizen scientists. He now says that the value of increased manpower is obvious — the volunteers have measured more than 150,000 trees, equivalent to 60 years’ work for one scientist. “Such information is often very time-consuming to collect, and many measurements cannot be monitored using remote sensing,” says Deborah Hemming, head of climate impacts analysis at the Met Office Hadley Centre in Exeter, UK. “The large amounts of data being collected by the programme’s citizen-science efforts will provide a significant benefit to further the scientific understanding of current and future potential impacts of climate change on global forests.”

Earthwatch plans to continue monitoring the sites in Brazil, China and India by working with local institutes. Ravindranath says that keeping the effort going is vital for Indian scientists. “There are no long-term monitoring studies on biodiversity as well as carbon stocks, and very limited modelling studies on climate-change impacts,” he says.

Source:Nature.

 

 

Adverse Drug Events Cause Many Hospitalizations in Elders.

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A few medications cause most of the problems that lead to emergency hospitalization in older patients.

Adverse drug events (ADEs) leading to emergency department (ED) visits or emergency hospitalizations are particularly common in older patients. The recent national focus on preventable rehospitalizations brings identifying and addressing high-risk medications to the healthcare forefront.

Investigators used 2007–2009 data from a nationally representative sample of 58 hospitals to estimate that nearly 100,000 emergency hospitalizations (1.5% of all emergency hospitalizations among elders) occurred annually due to medication injury in older patients (age, 65); they excluded cases of intentional self-harm, drug abuse, therapeutic failures, or drug withdrawal. Almost half (48%) of ADE-related hospitalizations among elders were in patients older than 80. Four medications accounted for more than two thirds of these ADE-related emergency hospitalizations: warfarin (33%), insulins (14%), oral antiplatelet agents (13%), and oral hypoglycemic agents (11%). Warfarin-related hemorrhages accounted for an estimated 21,000 emergency hospitalizations annually. Interestingly, medications designated as high risk by national quality measures (i.e., Healthcare Effectiveness Data and Information Set [HEDIS] high-risk medications or Beers-criteria potentially inappropriate medications) rarely caused emergency hospitalizations (1.2% and 6.6%, respectively) among older patients.

Comment: The nearly 100,000 annual emergency hospitalizations caused by ADEs in older patients represent an opportunity to prevent patient harm and lower healthcare use. Augmenting efforts to reconcile medications accurately at care transitions, as well as more aggressive drug monitoring for medications that commonly cause hospitalizations (including drug management programs), would help improve patient safety and prevent ADE-related hospitalizations. Policies to promote patient safety should target these identified medication classes for which evidence of patient harm exists.

Source: Journal Watch Hospital Medicine.

 

Stable Patients with Pulmonary Embolism Can Be Treated as Outpatients.

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 In a randomized trial of outpatient versus inpatient care, outcomes did not differ between groups.

Typically, diagnosis of pulmonary embolism (PE) means certain admission. Researchers performed an open-label, randomized, noninferiority study to compare outcomes of outpatient and inpatient treatment in consecutive adult patients who presented to 19 emergency departments in Europe and the U.S. with symptomatic PE and risk for death less than 4% (based on the PE Severity Index.. Patients were excluded if they had oxygen saturation <90% on room air, systolic blood pressure <100 mm Hg, chest pain requiring opioids, active bleeding, or were at high risk for hemorrhage (recent stroke or gastrointestinal bleeding or platelet count <75,000/mm3). All patients initially received subcutaneous enoxaparin (1 mg/kg twice daily) followed by anticoagulation with vitamin K antagonists for at least 90 days.

Overall, the study included 171 outpatients (mean age, 47) and 168 inpatients (mean age, 49). Cancer prevalence was 1% and 2%, respectively. Within 90 days, one patient in each group died, neither from PE. Recurrent venous thromboembolism occurred in only one patient (outpatient group). Major bleeding occurred within 90 days in three outpatients (intramuscular hematoma on day 3 and day 13 and menometrorrhagia on day 50) and no inpatients. At 14 days, more than 90% of patients in both groups were satisfied or very satisfied with treatment.

Comment: These data suggest that stable low-risk patients with PE can be safely and effectively treated as outpatients with low-molecular-weight heparin. The results might not be applicable to older patients than those in this study or to patients with cancer.

Source: Journal Watch Emergency Medicine.

 

Recurrent Clostridium difficile Infection: Enter Fidaxomicin.

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 Fidaxomicin significantly reduced the recurrence rate in patients infected with non-NAP1/BI/027 strains.

Recurrence of Clostridium difficile infection (CDI) is common, whether metronidazole or vancomycin is used as initial therapy. Fidaxomicin, a new macrocyclic antibiotic that has no cross-resistance with other antibiotics, is more active in vitro than vancomycin against clinical C. difficile isolates; in a phase II trial, it was associated with good clinical response and a low CDI recurrence rate. Now, in a manufacturer-sponsored, multicenter, double-blind, phase III trial, researchers have compared this agent with oral vancomycin in 629 adults with CDI.

Participants were randomized to receive fidaxomicin (200 mg twice daily) or vancomycin (125 mg 4 times daily) orally for 10 days. The primary endpoint was clinical cure (resolution of diarrhea; no need for additional CDI therapy as of posttreatment day 2). Secondary endpoints included CDI recurrence during the 4-week period after the end of therapy.

The clinical cure rates with fidaxomicin were noninferior to those with vancomycin in both the modified intention-to-treat (MITT) population (88.2% and 85.8%, respectively) and the per-protocol (PP) population (92.1% and 89.8%). Among patients infected with the NAP1/BI/027 strain, the recurrence rates were similar between treatment arms in the two populations. However, among those infected with non-NAP1/BI/027 strains, the recurrence rates differed dramatically between vancomycin and fidaxomicin in both the MITT population (28.1% vs. 10.3%; P<0.001) and the PP population (25.5% vs. 7.8%; P<0.001). The rates of adverse events and serious adverse events were similar between treatment arms.

Comment: On the basis of the findings from this investigation, an editorialist wrote that fidaxomicin appeared to be “an important advance.” I hope that this is the case — new, more-effective treatments for CDI are badly needed.

Source: Journal Watch Infectious Diseases.

 

Rivaroxaban Enters the Arsenal for Stroke Prevention in Arterial fibralition.

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Another anticoagulant proves noninferior to warfarin.

Rivaroxaban, an oral factor Xa inhibitor, might be a new alternative to warfarin for anticoagulation in patients with atrial fibrillation (AF). The ROCKET AF study was a multicenter, double-blind, industry-sponsored, randomized trial of once-daily oral rivaroxaban compared with dose-adjusted warfarin in moderate-to-high-risk patients with nonvalvular AF. The authors hypothesized that rivaroxaban is noninferior to warfarin at preventing the composite of stroke (ischemic and hemorrhagic) and systemic embolism. The 14,264 enrolled patients (median age, 73; 40% women) had a mean CHADS2 score of 3.5; about half had a CHADS2 score of 4.

Median follow-up was 707 days. In the warfarin group, the overall mean proportion of time in therapeutic international normalized ratio range was 55%. In the on-treatment noninferiority study, the primary event rate was 1.7% in rivaroxaban recipients and 2.2% in warfarin recipients (P<0.001 for noninferiority). In superiority analyses conducted after noninferiority was demonstrated, the primary event rate was slightly but significantly lower with rivaroxaban than with warfarin by on-treatment analysis but not by intention-to-treat analysis. The rate of major or nonmajor bleeding was similar in the two groups, although intracranial and fatal bleeding were significantly more common in warfarin recipients than in rivaroxaban recipients.

Comment: These findings were presented at the American Heart Association meeting in 2010, and the published article contains no surprises. The authors appropriately emphasize the noninferiority results and play down the superiority finding in the on-treatment analysis. They do highlight the lower intracranial and fatal bleeding rates in the rivaroxaban group, but these findings are more intriguing than definitive. This study supports adding rivaroxaban to the growing list of anticoagulant agents to prevent stroke and systemic embolism in patients with atrial fibrillation. So, how best to choose among these agents for particular patients given cost, compliance, and safety issues? Neither these investigators nor the authors of an accompanying editorial answer that question.

Source: Journal Watch Cardiology.

Norepinephrine Outperforms Dopamine in Adults with Septic Shock.

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Use of norepinephrine was associated with a 9% reduction in mortality compared with dopamine.

According to the Surviving Sepsis Campaign guidelines, norepinephrine or its precursor, dopamine, are both recommended as first-line treatments to improve organ perfusion in patients with septic shock. To determine which vasopressor is better, researchers conducted a meta-analysis of six randomized trials that compared the two agents in patients with septic shock and that reported in-hospital or 28-day mortality.

The trials included a total of 995 patients randomized to norepinephrine and 1048 randomized to dopamine. Overall, mortality was significantly lower in the norepinephrine group than in the dopamine group (48% vs. 53%). Arrhythmias were significantly less common with norepinephrine than with dopamine (relative risk, 0.43).

Comment: This study suggests that norepinephrine is superior to dopamine for adult patients with refractory septic shock. The finding that dopamine is associated with more arrhythmias might explain the higher mortality, as arrhythmias can impair cardiac function, thereby leading to worse outcomes.

Source: Journal Watch Emergency Medicine.

 

 

Physicists propose test for loop quantum gravity.

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As a quantum theory of gravity, loop quantum gravity could potentially solve one of the biggest problems in physics: reconciling general relativity and quantum mechanics. But like all tentative theories of quantum gravity, loop quantum gravity has never been experimentally tested. Now in a new study, scientists have found that, when black holes evaporate, the radiation they emit could potentially reveal “footprints” of loop quantum gravity, distinct from the usual Hawking radiation that black holes are expected to emit.

In this way, evaporating black holes could enable the first ever experimental test for any theory of quantum gravity. However, the proposed test would not be easy, since scientists have not yet been able to detect any kind of radiation from an evaporating black hole.

 

The scientists, from institutions in France and the US, have published their study called “Probing Loop Quantum Gravity with Evaporating Black Holes” in a recent issue of Physical Review Letters.

For decades, Planck-scale physics has been thought to be untestable,” coauthor Aurélien Barrau of the French National Institute of Nuclear and Particle Physics (IN2P3) told PhysOrg.com. “Nowadays, it seems that it might enter the realm of experimental physics! This is very exciting, especially in the appealing framework of loop quantum gravity.”

In their study, the scientists have used algorithms to show that primordial black holes are expected to reveal two distinct loop quantum gravity signatures, while larger black holes are expected to reveal one distinct signature. These signatures refer to features in the black hole’s energy spectrum, such as broad peaks at certain energy levels.

Using Monte Carlo simulations, the scientists estimated the circumstances under which they could discriminate the predicted signatures of loop quantum gravity and those of the Hawking radiation that black holes are expected to emit with or without loop quantum gravity. They found that a discrimination is possible as long as there are enough black holes or a relatively small error on the energy reconstruction.

While the scientists have shown that an analysis of black hole evaporation could possibly serve as a probe for loop quantum gravity, they note that one of the biggest challenges will be simply detecting evaporating black holes.

“We should be honest: this detection will be difficult,” Barrau said. “But it is far from being impossible.”

He added that black holes are not the only possible probe of loop quantum gravity, and he’s currently investigating whether loop quantum gravity might have signatures in the universe’s background radiation.

“I am now working on the cosmological side of loop quantum gravity,” Barrau said. “This is the other way to try to test the theory: some specific footprints in the cosmic microwave background might be detected in the future.”

Source:Physics.org.