Induced currents, frozen charges and the quantum Hall effect breakdown

Puzzling results obtained from torque magnetometry in the quantum Hall effect (QHE) regime are presented, and a theory is proposed for their explanation. Magnetic moment saturation, which is usually attributed to the QHE breakdown, is shown to be related to the charge redistribution across the sample.Comment: 5 pages, 2 figures, Proceedings of the 11th International Symposium "Nanostructures: Physics and Technology", St.Petersburg, Russia, June 23-28, 2003, expanded version with one figure adde

Pathogenic Potential to Humans of Bovine Escherichia coli O26, Scotland

Escherichia coli O26 and O157 have similar overall prevalences in cattle in Scotland, but in humans, Shiga toxin–producing E. coli O26 infections are fewer and clinically less severe than E. coli O157 infections. To investigate this discrepancy, we genotyped E. coli O26 isolates from cattle and humans in Scotland and continental Europe. The genetic background of some strains from Scotland was closely related to that of strains causing severe infections in Europe. Nonmetric multidimensional scaling found an association between hemolytic uremic syndrome (HUS) and multilocus sequence type 21 strains and confirmed the role of stx<sub>2</sub> in severe human disease. Although the prevalences of E. coli O26 and O157 on cattle farms in Scotland are equivalent, prevalence of more virulent strains is low, reducing human infection risk. However, new data on E. coli O26–associated HUS in humans highlight the need for surveillance of non-O157 enterohemorrhagic E. coli and for understanding stx<sub>2</sub> phage acquisition

Enzymatic activities and functional interdependencies of Bacillus subtilis lipoteichoic acid synthesis enzymes

Lipoteichoic acid (LTA) is an important cell wall polymer in Gram-positive bacteria. The enzyme responsible for polyglycerolphosphate LTA synthesis is LtaS, first described in Staphylococcus aureus. Four LtaS orthologues, LtaSBS, YfnI, YqgS and YvgJ, are present in Bacillus subtilis. Using an in vitro enzyme assay, we determined that all four proteins are Mn2+-dependent metal enzymes that use phosphatidylglycerol as a substrate. We show that LtaSBS, YfnI and YqgS can produce polymers, suggesting that these three proteins are bona-fide LTA synthases while YvgJ functions as an LTA primase, as indicated by the accumulation of a GroP-Glc2-DAG glycolipid. Western blot analysis of LTA produced by ltaSBS, yfnI, yqgS and yvgJ single, triple and the quadruple mutant, showed that LTA production was only abolished in the quadruple and the YvgJ-only expressing mutant. B. subtilis strains expressing YfnI in the absence of LtaSBS produced LTA of retarded mobility, presumably caused by an increase in chain length as suggested by a structural analysis of purified LTA. Taken together, the presented results indicate that the mere presence or absence of LTA cannot account for cell division and sporulation defects observed in the absence of individual enzymes and revealed an unexpected enzymatic interdependency of LtaS-type proteins in B. subtilis

Benchmark Framework for Virtual Students’ Behaviours

This paper demonstrates the integration and evaluation of different atmosphere models into Virtual Reality (VR) training for teacher education. We developed three behaviour models to simulate different levels of class discipline. We evaluated their performances using a combination of objective and subjective measurements. Our initial results suggest that the more believable and distinguishable classroom atmospheres are produced by creating more consistent behaviours across virtual students. Our results confirm the importance of similar behaviours to elicit a particular atmosphere

HIV Testing and ART Adherence Among Unstably Housed Black Men Who Have Sex with Men in the United States

Black men who have sex with men (BMSM) have the highest HIV incidence rate among all MSM in the United States (US), and are also disproportionately affected by homelessness and housing instability. However, little is known about the effects of homelessness on the HIV testing and care continuum for BMSM. Between 2014 and 2017, the Promoting Our Worth, Equality, and Resilience (POWER) study collected data and offered HIV testing to 4184 BMSM at Black Pride events in six US cities. Bivariate analyses were used to assess differences in sociodemographics and healthcare access between BMSM who self-reported homelessness and those who did not. Multivariable logistic regression models were used to assess differences in HIV testing by homelessness status. Finally, bivariate and multivariable models were used to assess differences in HIV care continuum and treatment adherence outcomes by homelessness status. 615 (12.1%) BMSM in our sample experienced homelessness in the last 12 months. BMSM who self-reported homelessness had higher odds of receiving an HIV test in the past 6 months compared to their stably housed counterparts. BMSM who self-reported homelessness had higher odds of reporting difficulty taking ART and of missing a dose in the past week compared to stably housed BMSM. Findings suggest that HIV testing outreach and treatment-related services targeting unstably housed BMSM may be effective. Future community-based research is needed to investigate how homelessness and housing instability affect ART adherence, and how this population may experience success in HIV testing and adherence despite economic and social marginalization

Microbial composition and omasal flows of bacterial, protozoal, and nonmicrobial amino acids in lactating dairy cows fed fresh perennial ryegrass (Lolium perenne L.) not supplemented or supplemented with rolled barley

peer-reviewedThe objective of this study was to evaluate the effect of rolled barley supplementation on microbial composition and omasal flows of bacterial, protozoal, and nonmicrobial AA in cows fed fresh perennial ryegrass (Lolium perenne L.; PRG). Ten ruminally cannulated multiparous Holstein cows averaging (mean ± standard deviation) 49 ± 23 d in milk and 513 ± 36 kg of body weight were assigned to 1 of 2 treatments in a switchback design. The treatment diets were PRG only or PRG plus 3.5 kg of dry matter rolled barley (G+RB). The study consisted of three 29-d periods where each period consisted of 21 d of diet adaptation and 8 d of data and sample collection. A double-marker system was used to quantify nutrient flow entering the omasal canal along with 15N-ammonium sulfate to label and measure the microbial and nonmicrobial omasal flow of AA. Overall, rolled barley supplementation had no effect on the AA composition of the omasal liquid-associated and particle-associated bacteria. Rolled barley supplementation affected the AA concentrations of omasal protozoa; however, the differences were nutritionally minor. Particle-associated bacteria AA flow was increased for all AA, except for Trp and Pro, in cows fed the G+RB diet. Rolled barley supplementation had no effect on protozoal AA flow. On average, protozoa accounted for 23% of the microbial essential AA flow, which ranged from 17 to 28% for Trp and Lys, respectively. The flow of all AA in omasal true digesta increased in cows fed the G+RB diet compared with the PRG-only diet, resulting in a 228 g/d increase in total AA flow in cows fed the G+RB diet. This increase in total AA flow in cows fed the G+RB diet was due to an increase in microbial AA flow. Rolled barley supplementation had no effect on nonmicrobial AA flow. The nonmicrobial AA flow modestly contributed to total AA flow, accounting for 15.6% on average. These results indicated that extensive ruminal degradation of PRG AA occurred (83.5%), and we demonstrated that cows consuming PRG-based diets exhibit a large dependence on microbial AA to support metabolizable AA supply. Rolled barley supplementation can increase the omasal flow of microbial AA in cows consuming PRG-based diets. However, further research is required to elucidate if this increased AA supply can support higher milk yield under such dietary conditions

Examining the Impact of a Psychosocial Syndemic on Past Six-Month HIV Screening Behavior of Black Men who have Sex with Men in the United States: Results from the POWER Study

Syndemic production theory has been used to explore HIV transmission risk or infections but has not been used to investigate prevention behavior, or with large samples of non-Whites. This analysis is the first to explore the impact of syndemic factors on previous six-month HIV screening behavior among US Black MSM. Data from Promoting Our Worth, Equality and Resilience (POWER) were analyzed from 3294 participants using syndemic variable counts and measures of interaction/synergy. Syndemic variables included: past three-month poly-drug use, depression, last year intimate partner violence, HIV risk and problematic binge drinking. BMSM reporting two syndemic factors were more likely to report screening (AOR = 1.37, 95% CI 1.04–1.80; p = 0.028) with no significant associations for three or more conditions. Measures of joint effect revealed that there were synergies among depression, problematic binge drinking and poly-drug use but these psychosocial factors cannot entirely explain testing patterns and excess disease burden among BMSM

Understanding the impact of a syndemic on the use of pre-exposure prophylaxis in a community-based sample of behaviorally PrEP-eligible BMSM in the United States

HIV Pre-Exposure Prophylaxis (PrEP) has shown great promise in reducing HIV transmission among affected populations; however, PrEP uptake among Black men who have sex with men (BMSM) has stalled. This study compares BMSM using PrEP and BMSM at risk for HIV not using PrEP based on differences in behavior, psychosocial conditions and the presence of a syndemic (n = 1,411). BMSM reporting PrEP use were significantly more likely to report three of five HIV risk behaviors and three of four psychosocial conditions. Odds of reporting PrEP use increased as the number of psychosocial conditions increased such that BMSM with three psychosocial conditions (AOR= 5.65, 95% CI: 3.17, 10.08) and four conditions (AOR = 18.34, 95% CI: 5.01, 67.20) demonstrated significantly greater odds of PrEP use compared to BMSM reporting one or less conditions. While BMSM at greatest risk are using PrEP, strategies are still needed for men at varying risk levels

Expectations and beliefs: How single young gay, bisexual and other men who have sex with men envision romantic relationships

We developed measures of relational beliefs and expectations among single young gay and bisexual men (YGBM). Data come from an online cross-sectional study YGBM, which ran from July 2012 until January 2013. There were 50 items on relational beliefs and 25 items on relational expectations. We used random split samples and a priori analysis to group items together and applied principal axis factoring with varimax orthogonal rotation. We had a total N = 1582 in our analytical sample and identified six constructs of relational expectations (restrictions, negative break up, masculine and gender norms, optimism, cheating, immediacy) and two constructs of relational beliefs (sex beliefs, equality). Our findings highlight specific relational cognitions among YGBM and offer insight into the beliefs and expectations that may inform their relationships. Findings may be useful for health professionals to help YGBM reflect and understand the health implications of their beliefs and expectations about same-sex relationships to promote healthy decision-making as they seek future partners

Rumen metabolism, omasal flow of nutrients, and microbial dynamics in lactating dairy cows fed fresh perennial ryegrass (Lolium perenne L.) not supplemented or supplemented with rolled barley grain

peer-reviewedThe objective of this study was to evaluate the effect of rolled barley grain (RB) supplementation on rumen metabolism, omasal flow of nutrients, and microbial dynamics in lactating dairy cows fed fresh perennial ryegrass (Lolium perenne L.; PRG)-based diets. Ten ruminally cannulated Holstein cows averaging (mean ± standard deviation) 49 ± 23 d in milk and 513 ± 36 kg of body weight were assigned to 1 of 2 treatments in a switchback design. The treatment diets were PRG only (G) or PRG plus 3.5 kg of dry matter RB (G+RB). The study consisted of three 29-d periods where each period consisted of 21 d of diet adaptation and 8 d of data and sample collection. A double marker system was used to quantify nutrient flow entering the omasal canal along with labeled 15N-ammonium sulfate to measure bacterial, protozoal, and nonmicrobial N flow. Rumen evacuation techniques were used to determine nutrient and microbial pool size, allowing the calculation of fractional rates of digestion and microbial growth. There was no difference in daily milk yield or energy-corrected milk yield between treatments. Milk fat concentration and milk urea N decreased, whereas milk protein concentration increased in cows fed the G+RB diet. During the omasal sampling phase, dry matter intake was higher in cows fed the G+RB diet. Ruminal and total-tract neutral detergent fiber digestibility was lower in G+RB cows; however, no difference was observed in reticulorumen pH. The rumen pool size of fermentable carbohydrate was increased in cows fed the G+RB diet; however, the fractional rate of digestion was decreased. Flow of nonammonia N and bacterial N at the omasal canal increased in cows fed the G+RB diet compared with the G diet. Protozoa N flow was not different between diets; however, protozoa appeared to supply a much larger amount of microbial N and exhibited shorter generation time than previously considered. Feed N ruminal digestibility, corrected for microbial contribution, was similar for both treatments (88.4 and 89.0% for G and G+RB, respectively). In conclusion, RB supplementation did not benefit overall animal performance; however, it reduced ruminal neutral detergent fiber digestibility and increased bacterial N flow. The results demonstrate the large dependence of cows consuming PRG-based diets on microbial N as the main source of nonammonia N supply. Additional quantitative research is required to further describe the supply of nutrients and microbial dynamics in cows consuming PRG-based diets in an effort to determine most limiting nutrients