Jamia Professor’s Paper included in the Nobel Prize Committee Document, 2011

                                                     Dynamics of dark energy

ln this paper we review in detail a number of approaches that have been adopted to try and explain
the remarkable observation of our accelerating Universe. ln particular we discuss the arguments for
and recent progress made towards understanding the nature of dark energy. We review the observa-
tional evidence for the current accelerated expansion of the universe and present a number of dark
energy models in addition to the conventional cosmological constant, paying particular attention to
scalar field models such as quintessence, K-essence, tachyon, phantom and dilatonic models. The
importance of cosmological scaling solutions is emphasized when studying the dynamical system of
scalar fields including coupled dark energy. We study the evolution of cosmological perturbations
allowing us to confront them with the observation of the Cosmic Microwave Background and Large
Scale Structure and demonstrate how it is possible in principle to reconstruct the equation of state
of dark energy by also using Supernovae la observational data. We also discuss in detail the nature
of tracking solutions in cosmology, particle physics and braneworld models of dark energy, the na-
ture of possible future singularities, the effect of higher order curvature terms to avoid a Big Rip
singularity, and approaches to modifying gravity which leads to a late-time accelerated expansion
without recourse to a new form of dark energy.

by Edmund J. Copeland, M. Sami, and Shinji Tsujikawa.

Prof M Sami,Department of theoretical physics,Jamai milla islamia, New Delhi,India.

Dutch Researcher Retracts First Paper, Offers ‘Apologies’

Today’s issue of Science contains the first official retraction of a paper by Diedrik Stapel, the Dutch social psychologist who allegedly made up or manipulated data in dozens of studies. The paper reported on a study finding that a messy physical environment promoted stereotyping and discrimination. Today’s retraction notes that an investigation by Tilburg University, for whom Stapel worked until recently, indicated the study’s data were fabricated. The retraction, which follows an Editorial Expression of Concern published after the university released its findings at the end of October, offers “apologies from author Stapel” and notes that “Coauthor Lindenberg was in no way involved in the generation of the data and agrees to the retraction of the paper.”

The co-author, Siegwart Lindenberg of the University of Groningen in Germany, e-mailed ScienceInsider last month that Stapel approached him after reading a paper in Science he had authored. They planned follow-up experiments that Stapel then said he carried out. “There was no reason to be suspicious in any way about what he presented to me as the results of the experiments he conducted,” Lindenberg noted in the e-mail sent soon after the university released its report. “I still believe that the possibility that disorder affects discrimination is an important idea and worthy of being tested in a way that is beyond suspicion. In fact, I believe that the series of experiments we planned also got to the heart of the possible mechanism. That this series seemingly has not been properly executed or (at least in part) even not executed at all, is therefore a doubly distressing fact.”

This issue of Science also contains an editorial on the Stapel scandal in which social psychologists Jennifer Crocker of Ohio State University and M. Lynne Cooper of the University of Missouri call on their field to take steps to prevent similar episodes:

Greater transparency with data, including depositing data in repositories where they can be accessed by other scientists (as is done in some other fields), might have sped up detection of this fraud, and it would certainly make researchers more careful about the analyses that they publish. Although many social psychologists are reluctant to share their data, fearing that their analyses will be criticized or they will be scooped, increasing transparency in this way is important. The zeitgeist around replication must also change, because replication is the cornerstone of a cumulative science. Thus, the field of social psychology needs to develop policies that facilitate and encourage systematic replication. And in all of the sciences, discussing issues related to data replication should become part of student training, along with developing better systems for reporting suspected misconduct or fraud.

Source: ScienceInsider


Drug Resistance Loiters on Antibiotic-Free Farms

Livestock farms that stop using antibiotics may still be breeding grounds for drug-resistant germs, according to a new study. Scientists have found that bacteria in a group of Canadian pigs remained mostly impervious to two antibiotics years after farmers stopped dosing the animals. This antibiotic resistance could eventually make its way into hospitals and the human food supply, although experts caution that no link has yet been proved.

Farmers regularly treat cattle, pigs, and chickens with antibiotics to dampen low-level infections that slow the growth of these animals. But wily bacteria quickly evolve resistance. Livestock farms often brim with resistant bugs that can pass to humans and potentially spread resistance to other microbes. Scientists hypothesized that if farmers stopped using the drugs, the bacteria would lower their defenses to save energy, eventually kicking out the DNA that codes for antibiotic resistance.

To figure out if this actually happens, ecologist Martin Chénier of McGill University in Montreal, Canada, and his colleagues examined bacteria on a university farm that in January 2007 banned all antibiotics, including two commonly used varieties: tylosin and chlortetracycline. They monitored gut bacterial populations in 10 pigs by searching for bacteria resistant to common drugs in their waste.

To the team’s surprise, the entire bug community kept most of its armor against the antibiotics, even after 2 ½ years. When the researchers grew the bacteria in the lab, for example, 70% to 100% of them were still resistant to chlortetracycline when the pigs were slaughtered. “I didn’t expect such high levels of resistance would remain,” says Chénier, whose team will publish the results in the January issue of Microbial Ecology.

Many resistance genes are easy to shed, Chénier notes. Bacteria often store them on circular pieces of DNA known as plasmids, which are not part of the microbes’ primary genome. Keeping these plasmids around costs energy, and if they’re not needed, the bacteria should kick them out within days. But many of the microbes Chénier’s team studied harbored a chlortetracycline resistance gene on plasmids, even after years without the antibiotic.

Chénier suspects the resistance genes may have stuck around because they’re linked to other genes bacteria need to survive. One hypothesis is that the other genes on the plasmids protect the animals from high levels of copper and zinc, metals found in pig feed. And as long as bugs hold on to resistance, they can share it with other bacteria they encounter.

Most farm screens have traced resistance only in pathogenic bugs—those that cause disease. But such organisms make up just a small percentage of gut microbes in pigs, Chénier notes. The new data, he says, suggest that the common practice of using swine waste as a fertilizer is like spreading truckloads of antibiotic resistance on farmland. Those bacteria can share their resistance with other bacteria that happen to be on crops and in downstream aquatic ecosystems—bacteria that could cause illness, Chénier says. “This is a time bomb.”

The study highlights the indirect consequences of antibiotic use that scientists have long worried about, says microbiologist Julie Zilles of the University of Illinois, Urbana-Champaign, who was not involved in the work. Still, she notes, it’s difficult to trace antibiotic resistance from animal farms to medical clinics.

The impact on the human food supply is also unclear, says H. Scott Hurd, an animal food safety expert with the World Health Organization and the University of Iowa, Ames. When scientists trace bacteria through meat production, he says, they find the meat to be safe. Employees at slaughterhouses and meat-processing facilities follow guidelines to keep the pigs’ gut bacteria from contaminating the rest of the meat and the facility, he notes. “Risk assessment shows us by the time food gets to the consumer, there’s very little resistant bacteria left.”

Still, Hurd says, although farmers have used chlortetracycline for 50 years, food-safety experts have monitored resistant strains only in the past decade. He agrees with Chénier about the need for more research on the spread of resistance genes from farms to the environment. “Clearly, we are creating resistant bacteria on the farm,” Hurd says. The new study “raises concern,” he says, “but doesn’t answer questions.”



Upper abdominal cytoreduction and thoracoscopy for advanced epithelial ovarian cancer: unanswered questions and the impact on treatment

Gynaecological oncologists, by conducting Phase II and III chemotherapy trials, have sought to improve survival in women with epithelial ovarian cancer. The greatest impact on survival has been the use of intraperitoneal chemotherapy in women who have had all visible disease removed. No change in drug regimen has had an impact on survival equivalent to that associated with complete cytoreduction or the use of intraperitoneal chemotherapy. Interestingly, these two treatment modalities (complete cytoreduction and intraperitoneal chemotherapy) have not been universally adopted. Most often it is the inability to achieve optimal cytoreduction in the upper abdomen that defines the limit of the cytoreductive effort, and ultimately the integration of intraperitoneal chemotherapy. The importance of identifying disease outside the abdominal cavity, along with achieving complete cytoreduction, is paramount, if the use of intraperitoneal chemotherapy is to be logically integrated in treatment algorithms for women with advanced-stage epithelial ovarian cancer. This report summarises pertinent literature on upper abdominal cytoreduction, discusses surgical techniques and introduces new data on women with epithelial ovarian cancer undergoing thoracoscopy, suggesting consideration of its incorporation into the surgical management of advanced epithelial ovarian cancer.



Nipple-Sparing Mastectomy for Prophylactic and Therapeutic Indications

Nipple-sparing mastectomy remains controversial and its adoption has been slow because of oncologic and surgical concerns.

Methods: A retrospective study evaluated all nipple-sparing mastectomies performed at a single institution for therapeutic or prophylactic indications for which records were available.

Results: Between 1989 and 2010, 162 nipple-sparing mastectomies were performed in 101 women. Forty-nine (30 percent) were performed for therapeutic purposes on 48 patients. A subareolar biopsy specimen was taken in 39 of 49 breasts (80 percent); four (10 percent) revealed ductal carcinoma in situ, and the nipple or nipple-areola complex was later removed. Four of 49 breasts (8 percent) in the therapeutic group had ischemic complications involving the nipple-areola complex, one of which (2 percent) was excised. With a mean follow-up of 2 years 6 months (range, 5 months to 9 years 5 months), no patients developed cancer in the nipple-areola complex. The remaining 113 mastectomies (70 percent) were performed prophylactically on 80 patients. The subareolar tissue was biopsied in 80 breasts (71 percent). One biopsy revealed lobular carcinoma in situ; none had ductal carcinoma in situ or invasive cancer. Two nipple-areola complexes (1.8 percent) were ischemic and excised. With a mean follow-up of 3 years 7 months (range, 5 months to 20 years 6 months), no patients developed new primary cancers in the nipple-areola complex.

Conclusions: Nipple-sparing mastectomy can be safe in properly selected patients. A subareolar biopsy can effectively identify nipple-areola complexes that may harbor cancerous cells. Ischemic complications resulting in nipple loss can be minimized, and long-term follow-up suggests that this technique deserves further investigation in properly selected patients.

source:American society of plastic surgery






Brain Hypoxia Is Associated With Short-term Outcome After Severe Traumatic Brain Injury Independently of Intracranial Hypertension and Low Cerebral Perfusion Pressure

Brain hypoxia (BH) can aggravate outcome after severe traumatic brain injury (TBI). Whether BH or reduced brain oxygen (Pbto2) is an independent outcome predictor or a marker of disease severity is not fully elucidated.

OBJECTIVE: To analyze the relationship between Pbto2, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) and to examine whether BH correlates with worse outcome independently of ICP and CPP.

METHODS: We studied 103 patients monitored with ICP and Pbto2 for > 24 hours. Durations of BH (Pbto2 < 15 mm Hg), ICP > 20 mm Hg, and CPP < 60 mm Hg were calculated with linear interpolation, and their associations with outcome within 30 days were analyzed.

RESULTS: Duration of BH was longer in patients with unfavorable (Glasgow Outcome Scale score, 1-3) than in those with favorable (Glasgow Outcome Scale, 4-5) outcome (8.3 ± 15.9 vs 1.7 ± 3.7 hours; P < .01). In patients with intracranial hypertension, those with BH had fewer favorable outcomes (46%) than those without (81%; P < .01); similarly, patients with low CPP and BH were less likely to have favorable outcome than those with low CPP but normal Pbto2 (39% vs 83%; P < .01). After ICP, CPP, age, Glasgow Coma Scale score, Marshall computed tomography grade, and Acute Physiology and Chronic Health Evaluation II score were controlled for, BH was independently associated with poor prognosis (adjusted odds ratio for favorable outcome, 0.89 per hour of BH; 95% confidence interval, 0.79-0.99; P = .04).

CONCLUSION: Brain hypoxia is associated with poor short-term outcome after severe traumatic brain injury independently of elevated ICP, low CPP, and injury severity. Pbto2 may be an important therapeutic target after severe traumatic brain injury.

source: neurosurgery

Inferior Field Loss Increases Rate of Falls in Older Adults with Glaucoma

Purpose. To examine the visual predictors of falls and injurious falls among older adults with glaucoma.

Methods. Prospective falls data were collected for 71 community-dwelling adults with primary open-angle glaucoma (mean age, 73.9 ± 5.7 years) for 1 year using monthly falls diaries. Baseline assessment of central visual function included high-contrast visual acuity and Pelli-Robson contrast sensitivity. Binocular integrated visual fields were derived from monocular Humphrey Field Analyzer plots. Rate ratios (RR) for falls and injurious falls with 95% confidence intervals (CIs) were based on negative binomial regression models.

Results. During the 1-year follow-up, 31 (44%) participants experienced at least one fall and 22 (31%) experienced falls that resulted in an injury. Greater visual impairment was associated with increased falls rate, independent of age and gender. In a multivariate model, more extensive field loss in the inferior region was associated with higher rate of falls (RR, 1.57; 95% CI, 1.06 to 2.32) and falls with injury (RR, 1.80; 95% CI, 1.12 to 2.98), adjusted for all other vision measures and potential confounding factors. Visual acuity, contrast sensitivity, and superior field loss were not associated with the rate of falls; topical beta-blocker use was also not associated with increased falls risk.

Conclusions. Falls are common among older adults with glaucoma and occur more frequently in those with greater visual impairment, particularly in the inferior field region. This finding highlights the importance of the inferior visual field region in falls risk and assists in identifying older adults with glaucoma at risk of future falls, for whom potential interventions should be targeted.

source:American academy of optometry