6,100 research outputs found
Synthesis Imaging of Dense Molecular Gas in the N113 HII Region of the Large Magellanic Cloud
We present aperture synthesis imaging of dense molecular gas in the Large
Magellanic Cloud, taken with the prototype millimeter receivers of the
Australia Telescope Compact Array (ATCA). Our observations of the N113 HII
region reveal a condensation with a size of ~6" (1.5 pc) FWHM, detected
strongly in the 1-0 lines of HCO+, HCN and HNC, and weakly in C_2H. Comparison
of the ATCA observations with single-dish maps from the Mopra Telescope and
sensitive spectra from the Swedish-ESO Submillimetre Telescope indicates that
the condensation is a massive clump of ~10^4 solar masses within a larger ~10^5
solar mass molecular cloud. The clump is centered adjacent to a compact,
obscured HII region which is part of a linear structure of radio continuum
sources extending across the molecular cloud. We suggest that the clump
represents a possible site for triggered star formation. Examining the
integrated line intensities as a function of interferometer baseline length, we
find evidence for decreasing HCO+/HCN and HCN/HNC ratios on longer baselines.
These trends are consistent with a significant component of the HCO+ emission
arising in an extended clump envelope and a lower HCN/HNC abundance ratio in
dense cores.Comment: 10 pages, 6 figures, to appear in Ap
Revisiting User Control: The Emergence and Success of a First Amendment Theory for the Internet Age
Screening for acquired cystic kidney disease: A decision analytic perspective
Screening for acquired cystic kidney disease: A decision analytic perspective. Acquired cystic kidney disease (ACKD) increases the risk of renal malignancy, and many authors suggest routine screening of dialysis patients for ACKD and renal tumors. However, they have defined neither the target population, the optimal screening strategy, the magnitude of its benefit, nor its risk. We used decision analysis to evaluate strategies of performing either computed tomography (CT) or ultrasound every three years on all dialysis patients and annually on patients found to have cysts. We compared these strategies to a strategy of seeking cysts and cancer only if these are clinically suspected. The baseline analysis shows that both CT and ultrasound may decrease cancer deaths by half for patients with a life expectancy of 25 years. Screening for ACKD offers these patients as much as a 1.6 year gain in life expectancy. However, for the majority of patients beginning renal replacement therapy, age or comorbid disease substantially limits life expectancy. For such patients, the gain in life expectancy from an ACKD screening program is measured in days. Sensitivity analyses show that the benefit of screening depends on the rate of malignant transformation, which needs better definition. The gain in life expectancy does not appear to be large enough to justify an ACKD screening program for the entire ESRD population. However, for the youngest and healthiest patients, a screening program would be of benefit. The magnitude of this benefit is uncertain, because the analysis was consistently biased in favor of the screening strategies
Decision making strategies used by experts and the potential for training intuitive skills: A preliminary study
New insights into the evolutionary history of plant sorbitol dehydrogenase
BACKGROUND:
Sorbitol dehydrogenase (SDH, EC 1.1.1.14) is the key enzyme involved in sorbitol metabolism in higher plants. SDH genes in some Rosaceae species could be divided into two groups. L-idonate-5-dehydrogenase (LIDH, EC 1.1.1.264) is involved in tartaric acid (TA) synthesis in Vitis vinifera and is highly homologous to plant SDHs. Despite efforts to understand the biological functions of plant SDH, the evolutionary history of plant SDH genes and their phylogenetic relationship with the V. vinifera LIDH gene have not been characterized
RESULTS:
A total of 92 SDH genes were identified from 42 angiosperm species. SDH genes have been highly duplicated within the Rosaceae family while monocot, Brassicaceae and most Asterid species exhibit singleton SDH genes. Core Eudicot SDHs have diverged into two phylogenetic lineages, now classified as SDH Class I and SDH Class II. V. vinifera LIDH was identified as a Class II SDH. Tandem duplication played a dominant role in the expansion of plant SDH family and Class II SDH genes were positioned in tandem with Class I SDH genes in several plant genomes. Protein modelling analyses of V. vinifera SDHs revealed 19 putative active site residues, three of which exhibited amino acid substitutions between Class I and Class II SDHs and were influenced by positive natural selection in the SDH Class II lineage. Gene expression analyses also demonstrated a clear transcriptional divergence between Class I and Class II SDH genes in V. vinifera and Citrus sinensis (orange)
CONCLUSIONS:
Phylogenetic, natural selection and synteny analyses provided strong support for the emergence of SDH Class II by positive natural selection after tandem duplication in the common ancestor of core Eudicot plants. The substitutions of three putative active site residues might be responsible for the unique enzyme activity of V. vinifera LIDH, which belongs to SDH Class II and represents a novel function of SDH in V. vinifera that may be true also of other Class II SDHs. Gene expression analyses also supported the divergence of SDH Class II at the expression level. This study will facilitate future research into understanding the biological functions of plant SDH
Screening for Asymptomatic Bacteriuria in Adults: US Preventive Services Task Force Recommendation Statement
Importance: Among the general adult population, women (across all ages) have the highest prevalence of asymptomatic bacteriuria, although rates increase with age among both men and women. Asymptomatic bacteriuria is present in an estimated 1% to 6% of premenopausal women and an estimated 2% to 10% of pregnant women and is associated with pyelonephritis, one of the most common nonobstetric reasons for hospitalization in pregnant women. Among pregnant persons, pyelonephritis is associated with perinatal complications including septicemia, respiratory distress, low birth weight, and spontaneous preterm birth.
Objective: To update its 2008 recommendation, the USPSTF commissioned a review of the evidence on potential benefits and harms of screening for and treatment of asymptomatic bacteriuria in adults, including pregnant persons.
Population: This recommendation applies to community-dwelling adults 18 years and older and pregnant persons of any age without signs and symptoms of a urinary tract infection.
Evidence Assessment: Based on a review of the evidence, the USPSTF concludes with moderate certainty that screening for and treatment of asymptomatic bacteriuria in pregnant persons has moderate net benefit in reducing perinatal complications. There is adequate evidence that pyelonephritis in pregnancy is associated with negative maternal outcomes and that treatment of screen-detected asymptomatic bacteriuria can reduce the incidence of pyelonephritis in pregnant persons. The USPSTF found adequate evidence of harms associated with treatment of asymptomatic bacteriuria (including adverse effects of antibiotic treatment and changes in the microbiome) to be at least small in magnitude. The USPSTF concludes with moderate certainty that screening for and treatment of asymptomatic bacteriuria in nonpregnant adults has no net benefit. The known harms associated with treatment include adverse effects of antibiotic use and changes to the microbiome. Based on these known harms, the USPSTF determined the overall harms to be at least small in this group.
Recommendations: The USPSTF recommends screening pregnant persons for asymptomatic bacteriuria using urine culture. (B recommendation) The USPSTF recommends against screening for asymptomatic bacteriuria in nonpregnant adults. (D recommendation)
Screening for Elevated Blood Lead Levels in Children and Pregnant Women: US Preventive Services Task Force Recommendation Statement
Importance: Elevated blood lead levels in children are associated with neurologic effects such as behavioral and learning problems, lower IQ, hyperactivity, hearing problems, and impaired growth. In pregnant women, lead exposure can impair organ systems such as the hematopoietic, hepatic, renal, and nervous systems, and increase the risk of preeclampsia and adverse perinatal outcomes. Many of the adverse health effects of lead exposure are irreversible.
Objective: To update the 2006 US Preventive Services Task Force (USPSTF) recommendation on screening for elevated blood lead levels in children and pregnant women.
Evidence Review: The USPSTF reviewed the evidence on the benefits and harms of screening for and treatment of elevated blood lead levels. In this update, an elevated blood lead level was defined according to the Centers for Disease Control and Prevention reference level of 5 mug/dL.
Findings: The USPSTF found adequate evidence that questionnaires and other clinical prediction tools to identify asymptomatic children with elevated blood lead levels are inaccurate. The USPSTF found adequate evidence that capillary blood testing accurately identifies children with elevated blood lead levels. The USPSTF found inadequate evidence on the effectiveness of treatment of elevated blood lead levels in asymptomatic children 5 years and younger and in pregnant women. The USPSTF found inadequate evidence regarding the accuracy of questionnaires and other clinical prediction tools to identify asymptomatic pregnant women with elevated blood lead levels. The USPSTF found inadequate evidence on the harms of screening for or treatment of elevated blood lead levels in asymptomatic children and pregnant women. The USPSTF concluded that the current evidence is insufficient, and that the balance of benefits and harms of screening for elevated blood lead levels in asymptomatic children 5 years and younger and in pregnant women cannot be determined.
Conclusions and Recommendation: The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for elevated blood lead levels in asymptomatic children. (I statement) The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for elevated blood lead levels in asymptomatic pregnant persons. (I statement)
Medication Use to Reduce Risk of Breast Cancer: US Preventive Services Task Force Recommendation Statement
Importance: Breast cancer is the most common nonskin cancer among women in the United States and the second leading cause of cancer death. The median age at diagnosis is 62 years, and an estimated 1 in 8 women will develop breast cancer at some point in their lifetime. African American women are more likely to die of breast cancer compared with women of other races.
Objective: To update the 2013 US Preventive Services Task Force (USPSTF) recommendation on medications for risk reduction of primary breast cancer.
Evidence Review: The USPSTF reviewed evidence on the accuracy of risk assessment methods to identify women who could benefit from risk-reducing medications for breast cancer, as well as evidence on the effectiveness, adverse effects, and subgroup variations of these medications. The USPSTF reviewed evidence from randomized trials, observational studies, and diagnostic accuracy studies of risk stratification models in women without preexisting breast cancer or ductal carcinoma in situ.
Findings: The USPSTF found convincing evidence that risk assessment tools can predict the number of cases of breast cancer expected to develop in a population. However, these risk assessment tools perform modestly at best in discriminating between individual women who will or will not develop breast cancer. The USPSTF found convincing evidence that risk-reducing medications (tamoxifen, raloxifene, or aromatase inhibitors) provide at least a moderate benefit in reducing risk for invasive estrogen receptor-positive breast cancer in postmenopausal women at increased risk for breast cancer. The USPSTF found that the benefits of taking tamoxifen, raloxifene, and aromatase inhibitors to reduce risk for breast cancer are no greater than small in women not at increased risk for the disease. The USPSTF found convincing evidence that tamoxifen and raloxifene and adequate evidence that aromatase inhibitors are associated with small to moderate harms. Overall, the USPSTF determined that the net benefit of taking medications to reduce risk of breast cancer is larger in women who have a greater risk for developing breast cancer.
Conclusions and Recommendation: The USPSTF recommends that clinicians offer to prescribe risk-reducing medications, such as tamoxifen, raloxifene, or aromatase inhibitors, to women who are at increased risk for breast cancer and at low risk for adverse medication effects. (B recommendation) The USPSTF recommends against the routine use of risk-reducing medications, such as tamoxifen, raloxifene, or aromatase inhibitors, in women who are not at increased risk for breast cancer. (D recommendation) This recommendation applies to asymptomatic women 35 years and older, including women with previous benign breast lesions on biopsy (such as atypical ductal or lobular hyperplasia and lobular carcinoma in situ). This recommendation does not apply to women who have a current or previous diagnosis of breast cancer or ductal carcinoma in situ
Widespread psychoactive pollutant augments daytime restfulness and disrupts diurnal activity rhythms in fish
Pharmaceutical pollution is a major driver of global change, with the capacity to alter key behavioural and physiological traits in exposed animals. Antidepressants are among the most commonly detected pharmaceuti-cals in the environment. Despite well-documented pharmacological effects of antidepressants on sleep in humans and other vertebrates, very little is known about their ecologically relevant impacts as pollutants on non-target wildlife. Accordingly, we investigated the effects of acute 3-day exposure of eastern mosquitofish (Gambusia holbrooki) to field-realistic levels (nominal concentrations: 30 and 300 ng/L) of the widespread psychoactive pollutant, fluoxetine, on diurnal activity patterns and restfulness, as indicators of disruptions to sleep. We show that exposure to fluoxetine disrupted diel activity patterns, which was driven by augmentation of daytime inactivity. Specifically, unexposed control fish were markedly diurnal, swimming farther during the day and exhibiting longer periods and more bouts of inactivity at night. However, in fluoxetine-exposed fish, this natural diel rhythm was eroded, with no differences in activity or restfulness observed between the day and night. As a misalignment in the circadian rhythm has been shown to adversely affect fecundity and lifespan in animals, our findings reveal a potentially serious threat to the survival and reproductive success of pollutant-exposed wildlife
- …