Fluorine negative ion detachment kinetics

A study of the rate of F(-) detachment by O and H atoms via the reactions F(-) + O yields FO + e and F(-) + H yields FH+ e was undertaken using a drift tube to produce F(-) ions at various drift velocities and therefore different ion temperatures. Preliminary mobility measurements of F(-) ions in Ar were made, indicating that ion temperatures in the 300 K to 5000 K range could be achieved; however due to numerous difficulties experienced in obtaining a reliable F(-) ion source, the study could not be completed

Alloreactive cytotoxic T lymphocytes generated in the presence of viral- derived peptides show exquisite peptide and MHC specificity

The nature of alloreactivity to MHC molecules has been enigmatic, primarily because of the observation that allogeneic responses are considerably stronger than syngeneic responses. To better determine the specificity potential of allogeneic responses, we have generated alloreactive CTL specific for exogenous, viral-derived peptide ligands. This approach allowed us to critically evaluate both the peptide- and MHC-specificity of these alloreactive T cells. Exploiting the accessibility of the H-2Ld class I molecule for exogenous peptide ligands, alloreactive CTL were generated that are specific for either murine cytomegalovirus (MCMV) or lymphocytic choriomeningitis virus (LCMV) peptides bound by Ld alloantigens. Peptide specificity was initially observed in bulk cultures of alloreactive CTL only when tested on peptide-sensitized T2.Ld target cells that have defective presentation of endogenous peptides. Subsequent cloning of bulk alloreactive CTL lines generated to MCMV yielded CTL clones that had exquisitely specific MCMV peptide recognition requirement. All of the MCMV/Ld alloreactive CTL clones were also exquisitely MHC-specific in that none of the CTL clones lysed targets expressing MCMV/Lq complexes, even though Lq differs from Ld by only six amino acid residues and Lq also binds the MCMV peptide. This observation clearly demonstrates that alloreactive CTL are capable of the same degree of specificity for target cell recognition as are syngeneic CTL in MHC-restricted responses

Wavenumbers for currents on infinite- and finite-length wires in a chiral medium

There is increasing interest in determining the electromagnetic properties of material media differing from free space and the effects thereof on the radiation, propagation, and scattering of electromagnetic fields. A material property of special present interest is that of chirality. Chirality manifests itself as a ``handedness`` wherein a chiral medium does not support propagation of a linearly-polarized plane wave, but which instead decomposes into two circularly-polarized waves that propagate at different speeds. Initial work in this area was devoted to developing various analytical solutions to some basic problems such as the Green`s Dyadic for a point current source. Attention is now being increasingly devoted to using this early work for a variety of applications such as analyzing antennas in chiral media scattering from chiral objects; scattering from objects having chiral coatings; and reflection from planar chiral interfaces. The focus of the work described here is determining the wavenumbers (={minus}{alpha}{minus}j{beta}) of the current waves excited on wire antennas located in an infinite chiral medium using two complementary approaches. One is to use an extension of an existing computer model (NEC) that permits modeling of arbitrary wire objects located in an infinite chiral medium. The other is to develop a solution for an infinitely long cylindrical antenna also located in an infinite chiral medium. The latter canonical problem is of interest in its own right as well as providing a means for achieving mutual validation with the NEC model. 9 refs

The Numerical Electromagnetics Code (NEC) - a brief history

The Numerical Electromagnetics Code, NEC as it is commonly known, continues to be one of the more widely used antenna modeling codes in existence. With several versions in use that reflect different levels of capability and availability, there are now 450 copies of NEC4 and 250 copies of NEC3 that have been distributed by Lawrence Livermore National Laboratory to a limited class of qualified recipients, and several hundred copies of NEC2 that had a recorded distribution by LLNL. These numbers do not account for numerous copies (perhaps 1000s) that were acquired through other means capitalizing on the open source code, the absence of distribution controls prior to NEC3 and the availability of versions on the Internet. In this paper we briefly review the history of the code that is concisely displayed in Figure 1. We will show how it capitalized on the research of prominent contributors in the early days of computational electromagnetics, how a combination of events led to the tri-service-supported code development program that ultimately led to NEC and how it evolved to the present day product. The authors apologize that space limitations do not allow us to provide a list of references or to acknowledge the numerous contributors to the code both of which can be found in the code documents

Health care provider decision-making and the quality of maternity care: an analysis of postpartum care in Kenyan hospitals

Evidence suggests that health care providers' non-adherence to clinical guidelines is widespread and contributes to poor patient outcomes across low- and middle-income countries. Through observations of maternity care in Kenya, we found limited adherence to guideline-recommended active monitoring of patients for signs of postpartum hemorrhage, the leading cause of maternal mortality, despite providers' having the necessary training and equipment. Using survey vignettes conducted with 144 maternity providers, we documented evidence consistent with subjective risk and perceived uncertainty driving providers' decisions to actively monitor patients. Motivated by these findings, we introduced a simple model of providers' decision-making about whether to monitor a patient, which may depend on their perceptions of risk, diagnostic uncertainty, and the value of new information. The model highlights key trade-offs between gathering diagnostic information through active monitoring versus waiting for signs and symptoms of hemorrhage to manifest. Our work provides a template for understanding provider decision-making and could inform interventions to encourage more proactive obstetric care

Health care providers' knowledge of clinical protocols for postpartum hemorrhage care in Kenya: a cross-sectional study

BACKGROUND: Postpartum hemorrhage (PPH) remains the leading cause of maternal death worldwide despite its often-preventable nature. Understanding health care providers' knowledge of clinical protocols is imperative for improving quality of care and reducing mortality. This is especially pertinent in referral and teaching hospitals that train nursing and medical students and interns in addition to managing emergency and referral cases. METHODS: This study aimed to (1) measure health care providers' knowledge of clinical protocols for risk assessment, prevention, and management of PPH in 3 referral hospitals in Kenya and (2) examine factors associated with providers' knowledge. We developed a knowledge assessment tool based on past studies and clinical guidelines from the World Health Organization and the Kenyan Ministry of Health. We conducted in-person surveys with health care providers in three high-volume maternity facilities in Nairobi and western Kenya from October 2018-February 2019. We measured gaps in knowledge using a summative index and examined factors associated with knowledge (such as age, gender, qualification, experience, in-service training attendance, and a self-reported measure of peer-closeness) using linear regression. RESULTS: We interviewed 172 providers including consultants, medical officers, clinical officers, nurse-midwives, and students. Overall, knowledge was lowest for prevention-related protocols (an average of 0.71 out of 1.00; 95% CI 0.69-0.73) and highest for assessment-related protocols (0.81; 95% CI 0.79-0.83). Average knowledge scores did not differ significantly between qualified providers and students. Finally, we found that being a qualified nurse, having a specialization, being female, having a bachelor's degree and self-reported closer relationships with colleagues were statistically significantly associated with higher knowledge scores. CONCLUSION: We found gaps in knowledge of PPH care clinical protocols in Kenya. There is a clear need for innovations in clinical training to ensure that providers in teaching referral hospitals are prepared to prevent, assess, and manage PPH. It is possible that training interventions focused on learning by doing and teamwork may be beneficial

Do HIV-Positive Women Receive Depression Treatment that Meets Best Practice Guidelines?

This study addressed whether psychopharmacologic and psychotherapeutic treatment of depressed HIV+ women met standards defined in the best practice literature, and tested hypothesized predictors of standard-concordant care. 1,352 HIV-positive women in the multi-center Women\u27s Interagency HIV Study were queried about depressive symptoms and mental health service utilization using standards published by the American Psychiatric Association and the Agency for Healthcare Research and Quality to define adequate depression treatment. We identified those who: (1) reported clinically significant depressive symptoms (CSDS) using Centers for Epidemiological Studies-Depression Scale scores of a parts per thousand yen16; or (2) had lifetime diagnoses of major depressive disorder (MDD) assessed by World Mental Health Composite International Diagnostic Interviews plus concurrent elevated depressive symptoms in the past 12 months. Adequate treatment prevalence was 46.2 % (n = 84) for MDD and 37.9 % (n = 211) for CSDS. Multivariable logistic regression analysis found that adequate treatment was more likely among women who saw the same primary care provider consistently, who had poorer self-rated role functioning, who paid out-of-pocket for healthcare, and who were not African American or Hispanic/Latina. This suggests that adequate depression treatment may be increased by promoting healthcare provider continuity, outreaching individuals with lower levels of reported role impairment, and addressing the specific needs and concerns of African American and Hispanic/Latina women

Detection of 6 K gas in Ophiuchus D

Cold cores in interstellar molecular clouds represent the very first phase in star formation. The physical conditions of these objects are studied in order to understand how molecular clouds evolve and how stellar masses are determined. The purpose of this study is to probe conditions in the dense, starless clump Ophichus D (Oph D). The ground-state (1(10)-1(11)) rotational transition of ortho-H2D+ was observed with APEX towards the density peak of Oph D. The width of the H2D+ line indicates that the kinetic temperature in the core is about 6 K. So far, this is the most direct evidence of such cold gas in molecular clouds. The observed H2D+ spectrum can be reproduced with a hydrostatic model with the temperature increasing from about 6 K in the centre to almost 10 K at the surface. The model is unstable against any increase in the external pressure, and the core is likely to form a low-mass star. The results suggest that an equilibrium configuration is a feasible intermediate stage of star formation even if the larger scale structure of the cloud is thought to be determined by turbulent fragmentation. In comparison with the isothermal case, the inward decrease in the temperature makes smaller, i.e. less massive, cores susceptible to externally triggered collapse.Comment: 7 pages, 5 figures, accepted for Astronomy and Astrophysic

Genome-wide association study to identify genetic loci associated with gastrointestinal nematode resistance in Katahdin sheep

Resistance to gastrointestinal nematodes has previously been shown to be a moderately heritable trait in some breeds of sheep, but the mechanisms of resistance are not well understood. Selection for resistance currently relies upon faecal egg counts (FEC), blood packed cell volumes and FAMACHA visual indicator scores of anaemia. Identifying genomic markers associated with disease resistance would potentially improve the selection process and provide a more reliable means of classifying and understanding the biology behind resistant and susceptible sheep. A GWAS was conducted to identify possible genetic loci associated with resistance to Haemonchus contortus in Katahdin sheep. Forty animals were selected from the top and bottom 10% of estimated breeding values for FEC from a total pool of 641 sires and ram lambs. Samples were genotyped using Applied BiosystemsTM AxiomTM Ovine Genotyping Array (50K) consisting of 51 572 SNPs. Following quality control, 46 268 SNPs were included in subsequent analyses. Analyses were conducted using a linear regression model in PLINK v1.90 and a single-locus mixed model in SNP AND VARIATION SUITE. Genome-wide significance was determined by a Bonferroni correction for multiple testing. Using linear regression, loci on chromosomes 2, 3, 16, 23 and 24 were significantly associated at the genome level with FEC estimated breeding values, and we identified a region on chromosome 2 that was significant using both statistical analyses. We suggest a potential role for the gene DIS3L2 for gastrointestinal nematode resistance in Katahdin sheep, although further research is needed to validate these findings

Transit Detection in the MEarth Survey of Nearby M Dwarfs: Bridging the Clean-First, Search-Later Divide

In the effort to characterize the masses, radii, and atmospheres of potentially habitable exoplanets, there is an urgent need to find examples of such planets transiting nearby M dwarfs. The MEarth Project is an ongoing effort to do so, as a ground-based photometric survey designed to detect exoplanets as small as 2 Earth radii transiting mid-to-late M dwarfs within 33 pc of the Sun. Unfortunately, identifying transits of such planets in photometric monitoring is complicated both by the intrinsic stellar variability that is common among these stars and by the nocturnal cadence, atmospheric variations, and instrumental systematics that often plague Earth-bound observatories. Here we summarize the properties of MEarth data gathered so far, and we present a new framework to detect shallow exoplanet transits in wiggly and irregularly-spaced light curves. In contrast to previous methods that clean trends from light curves before searching for transits, this framework assesses the significance of individual transits simultaneously while modeling variability, systematics, and the photometric quality of individual nights. Our Method for Including Starspots and Systematics in the Marginalized Probability of a Lone Eclipse (MISS MarPLE) uses a computationally efficient semi-Bayesian approach to explore the vast probability space spanned by the many parameters of this model, naturally incorporating the uncertainties in these parameters into its evaluation of candidate events. We show how to combine individual transits processed by MISS MarPLE into periodic transiting planet candidates and compare our results to the popular Box-fitting Least Squares (BLS) method with simulations. By applying MISS MarPLE to observations from the MEarth Project, we demonstrate the utility of this framework for robustly assessing the false alarm probability of transit signals in real data. [slightly abridged]Comment: accepted to the Astronomical Journal, 21 pages, 12 figure