Positive streamers in ambient air and a N2:O2-mixture (99.8 : 0.2)

Photographs show distinct differences between positive streamers in air or in a nitrogen-oxygen mixture (0.2% O2). The streamers in the mixture branch more frequently, but the branches also extinguish more easily. Probably related to that, the streamers in the mixture propagate more in a zigzag manner while they are straighter in air. Furthermore, streamers in the mixture can become longer; they are thinner and more intense.Comment: 2 pages, 4 figures, paper is accepted for IEEE Trans. Plasma Sci. and scheduled to appear in June 200

Quantitative and Qualitative Analysis on Sex and Gender in Preparatory Material for National Medical Examination in Germany and the United States

Background: Sex- and gender-based medicine (SGBM) should be a mandatory part of medical education. We compared the quantity and quality of sex- and gender-related content of e-learning materials commonly used by German and American medical students while preparing for national medical examinations. Methods: Quantitative, line-by-line analysis of the preparatory materials AMBOSS 2017 and USMLE Step 1 Lecture Notes (2017) by KAPLAN MEDICAL was performed between April and October 2017. Subjects were allocated to one of the three main fields: clinical subjects, behavioral and social science, and pharmacology. Qualitative analysis comprised binary categorization into sex- and gender-based aspects and qualification with respect to the presence of a pathophysiological explanation for the sex or gender difference. Results: In relation to the total content of AMBOSS and KAPLAN, the sex- and gender-based share of the clinical subjects content was 26.8% (±8.2) in AMBOSS and 21.1% (±10.2) in KAPLAN. The number of sex- and gender-based aspects in the behavioral and social science learning material differed significantly for AMBOSS and KAPLAN (4.4% ± 3.1% vs 10.7% ± 7.5%; P = .044). Most of the sex- and gender-related content covered sex differences. Most learning cards and texts did not include a detailed pathophysiological explanation for sex- or gender-based aspects. The knowledge provided in the preparatory documents represents only a small part of facts that are already known about sex and gender differences. Conclusions: The preparatory materials focused almost exclusively on biological sex differences and the sociocultural dimension in particular is underrepresented. A lot more evidence-based facts are known and should be integrated into the materials to reflect the importance of SGBM as an integral component of patient-centered medicine

Self-diffusion and Cooperative Diffusion in Semidilute Polymer Solutions as measured by Fluorescence Correlation Spectroscopy

We present a comprehensive investigation of polymer diffusion in the semidilute regime by fluorescence correlation spectroscopy (FCS) and dynamic light scattering (DLS). Using single-labeled polystyrene chains, FCS leads to the self-diffusion coefficient while DLS gives the cooperative diffusion coefficient for exactly the same molecular weights and concentrations. Using FCS we observe a new fast mode in the semidilute entangled concentration regime beyond the slower mode which is due to self-diffusion. Comparison of FCS data with data obtained by DLS on the same polymers shows that the second mode observed in FCS is identical to the cooperative diffusion coefficient measured with DLS. An in-depth analysis and a comparison with current theoretical models demonstrates that the new cooperative mode observed in FCS is due to the effective long-range interaction of the chains through the transient entanglement network

Positive and negative streamers in ambient air: measuring diameter, velocity and dissipated energy

Positive and negative streamers are studied in ambient air at 1 bar; they emerge from a needle electrode placed 40 mm above a planar electrode. The amplitudes of the applied voltage pulses range from 5 to 96 kV; most pulses have rise times of 30 ns or shorter. Diameters, velocities and energies of the streamers are measured. Two regimes are identified; a low voltage regime where only positive streamers appear and a high voltage regime where both positive and negative streamers exist. Below 5 kV, no streamers emerge. In the range from 5 to 40 kV, positive streamers form, while the negative discharges only form a glowing cloud at the electrode tip, but no streamers. For 5 to 20 kV, diameters and velocities of the positive streamers have the minimal values of d=0.2 mm and v \approx 10^5 m/s. For 20 to 40 kV, their diameters increase by a factor 6 while the voltage increases only by a factor 2. Above the transition value of 40 kV, streamers of both polarities form; they strongly resemble each other, though the positive ones propagate further; their diameters continue to increase with applied voltage. For 96 kV, positive streamers attain diameters of 3 mm and velocities of 4*10^6 m/s, negative streamers are about 20 % slower and thinner. An empirical fit formula for the relation between velocity v and diameter d is v=0.5 d^2/(mm ns) for both polarities. Streamers of both polarities dissipate energies of the order of several mJ per streamer while crossing the gap.Comment: 20 pages, 9 figures, accepted for J. Phys.

The prospective association between obesity and major depression in the general population:does single or recurrent episode matter?

Background: Obesity and major depressive disorder (MDD) are important public health problems. MDD is a heterogeneous disorder and the direction of its association with obesity remains unclear. Evidence grows that recurrent MDD (MDD-R) differs in etiology and prognosis from single episode MDD (MDD-S), which could affect associations with obesity. However, evidence on this differential effect is lacking. The aim of this study was to examine the direction of the association between obesity and MDD, single or recurrent episode. Methods: A longitudinal study was performed in a cohort of 1094 participants of the PREVEND study, on whom data were collected at baseline and at an average 2-year follow-up. MDD-S and MDD-R were assessed by the Composite International Diagnostic Interview (CIDI 2.1). Obesity was defined as Body Mass Index >= 30 kg/m(2). Binary logistic regression analyses were conducted to examine whether obesity predicts MDD-S/MDD-R or vice versa, adjusted for potential confounders. Results: Prospective analyses showed that BMI at baseline was associated with the onset of MDD-R (Odds ratio, OR = 1.32; 95% confidence interval, 95% CI: 1.11; 1.57) during 2-year follow-up, but not with the onset of MDD-S (OR = 0.98; 95% CI: 0.89; 1.07). Obesity at baseline was not associated with the onset of MDD-S during follow-up (OR = 0.75; 95% CI: 0.25; 2.30), but associated with the onset of MDD-R during follow-up (OR = 11.63; 95% CI: 1.05; 128.60). Neither MDD-S nor MDD-R were associated with the development of obesity during 2-year follow-up (OR = 1.67, 95% CI: 0.64; 4.29 and OR = 2.32, 95% CI: 0.82; 6.58, respectively). Conclusions: Our findings add to the available evidence that obesity might specifically be associated with the onset of multiple episodes of major depression (MDD-R). Although the reverse association was not found, MDD-R tends to be also associated with subsequent development of obesity, but larger studies are needed to fully assess this issue. The heterogeneity of MDD should be considered when examining the effect of obesity on MDD

Transformational instructor-leadership and academic performance: a moderated mediation model of student engagement and structural distance

Researchers are becoming increasingly interested in the use of transformational leadership theory in higher education teaching (often referred to as transformational instructor-leadership). Much of this body of research investigates a direct association between transformational instructor-leadership and student outcomes. In the present study, we take a step further by investigating (a) student engagement as a mechanism in the relationship between transformational instructor-leadership and students’ academic performance and (b) structural distance as a moderator of the relationship between transformational instructor-leadership and student engagement. Using a sample of 183 students across the UK, the findings supported student engagement as a full mediator, but did not support structural distance as a moderator. This study contributes to theory by (a) showing a key underlying process through which transformational instructor-leadership is related to students’ academic performance and (b) empirically examining all three dimensions of student engagement. Limitations, suggestions for future research and practical implications are discussed

Positive streamers in air and nitrogen of varying density: experiments on similarity laws

Positive streamers in ambient air at pressures from 0.013 to 1 bar are investigated experimentally. The voltage applied to the anode needle ranges from 5 to 45 kV, the discharge gap from 1 to 16 cm. Using a "slow" voltage rise time of 100 to 180 ns, the streamers are intentionally kept thin. For each pressure p, we find a minimal diameter d_{min}. To test whether streamers at different pressures are similar, the minimal streamer diameter d_{min} is multiplied by its pressure p; we find this product to be well approximated by p*d_{min}=0.20 \pm 0.02 mm*bar over two decades of air pressure at room temperature. The value also fits diameters of sprite discharges above thunderclouds at an altitude of 80 km when extrapolated to room temperature (as air density rather than pressure determines the physical behavior). The minimal velocity of streamers in our measurements is approximately 0.1 mm/ns = 10^5 m/s. The same minimal velocity has been reported for tendrils in sprites. We also investigate the size of the initial ionization cloud at the electrode tip from which the streamers emerge, and the streamer length between branching events. The same quantities are also measured in nitrogen with a purity of approximately 99.9 %. We characterize the essential differences with streamers in air and find a minimal diameter of p*d_{min}=0.12 \pm 0.02 mm*bar in our nitrogen.Comment: 24 pages, 11 figures, accepted for J. Phys.

Draft Genome Sequence of the Antitrypanosomally Active Sponge-Associated Bacterium Actinokineospora sp. Strain EG49

The marine sponge-associated bacterium Actinokineospora sp. strain EG49 produces the antitrypanosomal angucycline-like compound actinosporin A. The draft genome of Actinokineospora sp. EG49 has a size of 7.5 megabases and a GC content of 72.8% and contains 6,629 protein-coding sequences (CDS). antiSMASH predicted 996 genes residing in 36 secondary metabolite gene clusters

Athletic trainers\u27 or athletic training students\u27 perceptions of sexual harassment by student-athletes in the collegiate setting

Sexual harassment is an issue that occurs in healthcare professions and on college campuses nationwide. Athletic trainers employed at the collegiate setting are healthcare professionals who work in close conjunction with student-athletes, which may predispose a risk of a sexual harassment occurrence. A study was conducted to investigate the sexual harassment of athletic trainers and athletic training students by student athletes at the collegiate setting. A Qualtrics survey, containing closed- and open-ended questions, was sent out to 297 CAATE-accredited athletic training program directors; the athletic training staff at these institutions were also sent the survey as well. The program directors were asked to send the survey to the students currently enrolled in the program. Quantitative data were analyzed using Qualtrics and the qualitative data were analyzed using themes and coding. The study revealed that athletic trainers and athletic training students were sexually harassed by student-athletes on at least one occasion. 40% of the respondents stated being sexually harassed by a student-athlete, and 59% observed sexual harassment of a member of the athletic training staff on at least one instance