1,771 research outputs found
Discovery and Follow-up Observations of the Young Type Ia Supernova 2016coj
The Type~Ia supernova (SN~Ia) 2016coj in NGC 4125 (redshift ) was
discovered by the Lick Observatory Supernova Search 4.9 days after the fitted
first-light time (FFLT; 11.1 days before -band maximum). Our first detection
(pre-discovery) is merely day after the FFLT, making SN 2016coj one
of the earliest known detections of a SN Ia. A spectrum was taken only 3.7 hr
after discovery (5.0 days after the FFLT) and classified as a normal SN Ia. We
performed high-quality photometry, low- and high-resolution spectroscopy, and
spectropolarimetry, finding that SN 2016coj is a spectroscopically normal SN
Ia, but with a high velocity of \ion{Si}{2} 6355 (\,\kms\
around peak brightness). The \ion{Si}{2} 6355 velocity evolution can
be well fit by a broken-power-law function for up to a month after the FFLT. SN
2016coj has a normal peak luminosity ( mag), and it
reaches a -band maximum \about16.0~d after the FFLT. We estimate there to be
low host-galaxy extinction based on the absence of Na~I~D absorption lines in
our low- and high-resolution spectra. The spectropolarimetric data exhibit weak
polarization in the continuum, but the \ion{Si}{2} line polarization is quite
strong () at peak brightness.Comment: Submitte
Assessment of Emergency Medicine Resident Performance in an Adult Simulation Using a Multisource Feedback Approach.
Introduction: The Accreditation Council for Graduate Medical Education (ACGME) specifically notes multisource feedback (MSF) as a recommended means of resident assessment in the emergency medicine (EM) Milestones. High-fidelity simulation is an environment wherein residents can receive MSF from various types of healthcare professionals. Previously, the Queen\u27s Simulation Assessment Tool (QSAT) has been validated for faculty to assess residents in five categories: assessment; diagnostic actions; therapeutic actions; interpersonal communication, and overall assessment. We sought to determine whether the QSAT could be used to provide MSF using a standardized simulation case.
Methods: Prospectively after institutional review board approval, residents from a dual ACGME/osteopathic-approved postgraduate years (PGY) 1-4 EM residency were consented for participation. We developed a standardized resuscitation after overdose case with specific 1-5 Likert anchors used by the QSAT. A PGY 2-4 resident participated in the role of team leader, who completed a QSAT as self-assessment. The team consisted of a PGY-1 peer, an emergency medical services (EMS) provider, and a nurse. Two core faculty were present to administer the simulation case and assess. Demographics were gathered from all participants completing QSATs. We analyzed QSATs by each category and on cumulative score. Hypothesis testing was performed using intraclass correlation coefficients (ICC), with 95% confidence intervals. Interpretation of ICC results was based on previously published definitions.
Results: We enrolled 34 team leader residents along with 34 nurses. A single PGY-1, a single EMS provider and two faculty were also enrolled. Faculty provided higher cumulative QSAT scores than the other sources of MSF. QSAT scores did not increase with team leader PGY level. ICC for inter-rater reliability for all sources of MSF was 0.754 (0.572-0.867). Removing the self-evaluation scores increased inter-rater reliability to 0.838 (0.733-0.910). There was lesser agreement between faculty and nurse evaluations than from the EMS or peer evaluation.
Conclusion: In this single-site cohort using an internally developed simulation case, the QSAT provided MSF with excellent reliability. Self-assessment decreases the reliability of the MSF, and our data suggest self-assessment should not be a component of MSF. Use of the QSAT for MSF may be considered as a source of data for clinical competency committees
Endocrine Regulation of Male Fertility by the Skeleton
Although the endocrine capacity of bone is widely recognized, interactions between bone and the reproductive system have until now focused on the gonads as a regulator of bone remodeling. We now show that in males, bone acts as a regulator of fertility. Using co-culture assays, we demonstrate that osteoblasts are able to induce testosterone production by the testes, while they fail to influence estrogen production by the ovaries. Analyses of cell-specific loss- and gain-of-function models reveal that the osteoblast-derived hormone osteocalcin performs this endocrine function. By binding to a G-protein coupled receptor expressed in the Leydig cells of the testes, osteocalcin regulates in a CREB-dependent manner the expression of enzymes required for testosterone synthesis, promoting germ cell survival. This study expands the physiological repertoire of osteocalcin, and provides the first evidence that the skeleton is an endocrine regulator of reproduction
Convergence Of Soil Nitrogen Isotopes Across Global Climate Gradients
Quantifying global patterns of terrestrial nitrogen (N) cycling is central to predicting future patterns of primary productivity, carbon sequestration, nutrient fluxes to aquatic systems, and climate forcing. With limited direct measures of soil N cycling at the global scale, syntheses of the N-15 : N-14 ratio of soil organic matter across climate gradients provide key insights into understanding global patterns of N cycling. In synthesizing data from over 6000 soil samples, we show strong global relationships among soil N isotopes, mean annual temperature (MAT), mean annual precipitation (MAP), and the concentrations of organic carbon and clay in soil. In both hot ecosystems and dry ecosystems, soil organic matter was more enriched in N-15 than in corresponding cold ecosystems or wet ecosystems. Below a MAT of 9.8 degrees C, soil delta N-15 was invariant with MAT. At the global scale, soil organic C concentrations also declined with increasing MAT and decreasing MAP. After standardizing for variation among mineral soils in soil C and clay concentrations, soil delta N-15 showed no consistent trends across global climate and latitudinal gradients. Our analyses could place new constraints on interpretations of patterns of ecosystem N cycling and global budgets of gaseous N loss.
Localization of telomeres and telomere-associated proteins in telomerase-negative Saccharomyces cerevisiae
Cells lacking telomerase cannot maintain their telomeres and undergo a telomere erosion phase leading to senescence and crisis in which most cells become nonviable. On rare occasions survivors emerge from these cultures that maintain their telomeres in alternative ways. The movement of five marked telomeres in Saccharomyces cerevisiae was followed in wild-type cells and through erosion, senescence/crisis and eventual survival in telomerase-negative (est2::HYG) yeast cells. It was found that during erosion, movements of telomeres in est2::HYG cells were indistinguishable from wild-type telomere movements. At senescence/crisis, however, most cells were in G2 arrest and the nucleus and telomeres traversed back and forth across the bud neck, presumably until cell death. Type I survivors, using subtelomeric Y′ amplification for telomere maintenance, continued to show this aberrant telomere movement. However, Type II survivors, maintaining telomeres by a sudden elongation of the telomere repeats, became indistinguishable from wild-type cells, consistent with growth properties of the two types of survivors. When telomere-associated proteins Sir2p, Sir3p and Rap1p were tagged, the same general trend was seen—Type I survivors retained the senescence/crisis state of protein localization, while Type II survivors were restored to wild type
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