Hydrogen molecule in a magnetic field: The lowest states of the Pi manifold and the global ground state of the parallel configuration

The electronic structure of the hydrogen molecule in a magnetic field is investigated for parallel internuclear and magnetic field axes. The lowest states of the $\Pi$ manifold are studied for spin singlet and triplet$(M_s = -1)$ as well as gerade and ungerade parity for a broad range of field strengths $0 \leq B \leq 100 a.u.$ For both states with gerade parity we observe a monotonous decrease in the dissociation energy with increasing field strength up to $B = 0.1 a.u.$ and metastable states with respect to the dissociation into two H atoms occur for a certain range of field strengths. For both states with ungerade parity we observe a strong increase in the dissociation energy with increasing field strength above some critical field strength $B_c$. As a major result we determine the transition field strengths for the crossings among the lowest $^1\Sigma_g$, $^3\Sigma_u$ and $^3\Pi_u$ states. The global ground state for $B \lesssim 0.18 a.u.$ is the strongly bound $^1\Sigma_g$ state. The crossings of the $^1\Sigma_g$ with the $^3\Sigma_u$ and $^3\Pi_u$ state occur at $B \approx 0.18$ and $B \approx0.39 a.u.$, respectively. The transition between the $^3\Sigma_u$ and $^3\Pi_u$ state occurs at $B \approx 12.3 a.u.$ Therefore, the global ground state of the hydrogen molecule for the parallel configuration is the unbound $^3\Sigma_u$ state for $0.18 \lesssim B \lesssim 12.3 a.u.$ The ground state for $B \gtrsim 12.3 a.u.$ is the strongly bound $^3\Pi_u$ state. This result is of great relevance to the chemistry in the atmospheres of magnetic white dwarfs and neutron stars.Comment: submitted to Physical Review

Confirmation that “Brachyspira hampsonii” clade I (Canadian strain 30599) causes mucohemorrhagic diarrhea and colitis in experimentally infected pigs

BACKGROUND: “Brachyspira hampsonii”, discovered in North America in 2010 associated with dysentery-like illness, is an economically relevant swine pathogen resulting in decreased feed efficiency and increased morbidity, mortality and medication usage. “B. hampsonii” clade II strain 30446 has been shown to be causally associated with mucohemorrhagic diarrhea and colitis. Our objectives were to determine if “Brachyspira hampsonii” clade I strain 30599 is pathogenic to pigs, and to evaluate the relative diagnostic performance of three ante mortem sampling methodologies (direct PCR on feces, PCR on rectal GenoTube Livestock swabs, Brachyspira culture from rectal swabs). Five-week old pigs were intragastrically inoculated thrice with 10(8) genomic equivalents "B. hampsonii" (n = 12), or served as sham controls (n = 6). Feces were sampled and consistency assessed daily. Necropsies were performed 24 h after peak clinical signs. RESULTS: One pig died due to unrelated illness. Nine of 11 inoculated pigs, but no controls, developed mucoid or mucohemorrhagic diarrhea (MHD). Characteristic lesions of swine dysentery were observed in large intestine. “B. hampsonii” strain 30599 DNA was detected by qPCR in feces of all inoculated pigs for up to 6 days prior to the onset of MHD. The organism was isolated from the feces and colons of pigs demonstrating MHD, but not from controls. B. intermedia was isolated from inoculated pigs without MHD, and from 5 of 6 controls. CONCLUSIONS: We conclude that “Brachyspira hampsonii” clade I strain 30599 is pathogenic and causes mucohemorrhagic diarrhea and colitis in susceptible pigs. Moreover, the three sampling methodologies performed similarly. GenoTube Livestock, a forensic swab designed to preserve DNA during shipping is a useful tool especially in settings where timely transport of diagnostic samples is challenging

P20-16. Ultra-deep pyrosequencing detects complex patterns of CD8+ T-lymphocyte escape in SIV-infected macaques

Background A complex population of viral variants exists within each individual infected with immunodeficiency virus. Deciphering the breadth and frequency of accruing viral mutations provides insight into immune responses, drug resistance, and potential vaccine targets. Contemporary sequencing methods are limited to detection of high frequency variants, leading to an incomplete assessment of the overall viral population. Here, we use ultra-deep pyrosequencing to create a comprehensive picture of CD8+ T-lymphocyte (CD8-TL) escape in two epitopes in SIV-infected rhesus and cynomolgus macaques, revealing a complex pattern of viral variants previously undetected. Methods Plasma was collected from SIV-infected rhesus and cynomolgus macaques at multiple timepoints between weeks 1 and 20 post-infection. Viral RNA was isolated and amplicons spanning the epitopes of interest were generated by RT-PCR, using primers that incorporated a unique 10 bp molecular barcode into each sample. Amplicons were pooled and sequenced on a Roche Genome Sequencer FLX instrument and analyzed using Roche Amplicon Variant Analyzer software. Results The increased sensitivity of ultra-deep pyrosequencing enabled detection of acute CD8-TL escape as early as 17 days post-infection, representing the earliest published example of CD8-TL escape in intrarectally infected macaques. Conversely, we observed the continued presence of a complex viral population well into chronic infection, indicating that viral mutations deemed ''fixed'' by Sanger sequencing are instead complemented by a broad array of viral variants. Additionally, we show that these methods can be applied to sequencing of the entire SIVmac239 genome, supporting the continued use of pyrosequencing in comprehensive SIV infection studies. Conclusion Overall, these findings demonstrate that pyrosequencing can be used to study viral evolution during HIV/SIV infection with an unprecedented degree of sensitivity. Utilizing newly emerging molecular tools is essential and will further our understanding of how viral pathogens evade the immune system

Exchange and correlation energies of ground states of atoms and molecules in strong magnetic fields

Using a Hartree-Fock mesh method and a configuration interaction approach based on a generalized Gaussian basis set we investigate the behaviour of the exchange and correlation energies of small atoms and molecules, namely th e helium and lithium atom as well as the hydrogen molecule, in the presence of a magnetic field covering the regime B=0-100a.u. In general the importance of the exchange energy to the binding properties of at oms or molecules increases strongly with increasing field strength. This is due to the spin-flip transitions and in particular due to the contributions of the tightly bound hydrogenic state s which are involved in the corresponding ground states of different symmetries. In contrast to the exchange energy the correlation energy becomes less relevant with increasing field strength. This holds for the individual configurations constituting the ground state and for the crossovers of the global ground state.Comment: 4 Figures acc.f.publ.in Phys.Rev.

A stimulus to define informatics and health information technology

<p>Abstract</p> <p>Background</p> <p>Despite the growing interest by leaders, policy makers, and others, the terminology of health information technology as well as biomedical and health informatics is poorly understood and not even agreed upon by academics and professionals in the field.</p> <p>Discussion</p> <p>The paper, presented as a Debate to encourage further discussion and disagreement, provides definitions of the major terminology used in biomedical and health informatics and health information technology. For informatics, it focuses on the words that modify the term as well as individuals who practice the discipline. Other categories of related terms are covered as well, from the associated disciplines of computer science, information technolog and health information management to the major application categories of applications used. The discussion closes with a classification of individuals who work in the largest segment of the field, namely clinical informatics.</p> <p>Summary</p> <p>The goal of presenting in Debate format is to provide a starting point for discussion to reach a documented consensus on the definition and use of these terms.</p

Heuristic Reasoning and the Observer's View: The Influence of Example-Availability on ad-hoc Frequency Judgments in Sport

Drawing upon evidence from broader social psychology, and an illustrative study of frequency estimation during a simple, sport-specific observe-and-recall task, this paper makes the case for the more thorough investigation of the availability heuristic (Tversky & Kahneman, 1973) on practical state-of-play reasoning in largely observational sporting activities. It is argued that this evidence particularly substantiates a need for a more robust body of research in two primary domains: (a) the gatekeeping tasks pertinent (and usually preliminary) to an individual’s sporting performance such as talent scouting, team selection, and substitution decisions, and (b) the business of officiating in high-tempo environments

Cytokinesis in bloodstream stage Trypanosoma brucei requires a family of katanins and spastin

Microtubule severing enzymes regulate microtubule dynamics in a wide range of organisms and are implicated in important cell cycle processes such as mitotic spindle assembly and disassembly, chromosome movement and cytokinesis. Here we explore the function of several microtubule severing enzyme homologues, the katanins (KAT80, KAT60a, KAT60b and KAT60c), spastin (SPA) and fidgetin (FID) in the bloodstream stage of the African trypanosome parasite, Trypanosoma brucei. The trypanosome cytoskeleton is microtubule based and remains assembled throughout the cell cycle, necessitating its remodelling during cytokinesis. Using RNA interference to deplete individual proteins, we show that the trypanosome katanin and spastin homologues are non-redundant and essential for bloodstream form proliferation. Further, cell cycle analysis revealed that these proteins play essential but discrete roles in cytokinesis. The KAT60 proteins each appear to be important during the early stages of cytokinesis, while downregulation of KAT80 specifically inhibited furrow ingression and SPA depletion prevented completion of abscission. In contrast, RNA interference of FID did not result in any discernible effects. We propose that the stable microtubule cytoskeleton of T. brucei necessitates the coordinated action of a family of katanins and spastin to bring about the cytoskeletal remodelling necessary to complete cell divisio

Evaluation of a Web Portal for Improving Public Access to Evidence-Based Health Information and Health Literacy Skills: A Pragmatic Trial

Background: Using the conceptual framework of shared decision-making and evidence-based practice, a web portal was developed to serve as a generic (non disease-specific) tailored intervention to improve the lay public’s health literacy skills. Objective: To evaluate the effects of the web portal compared to no intervention in a real-life setting. Methods: A pragmatic randomised controlled parallel trial using simple randomisation of 96 parents who had children aged ,4 years. Parents were allocated to receive either access to the portal or no intervention, and assigned three tasks to perform over a three-week period. These included a searching task, a critical appraisal task, and reporting on perceptions about participation. Data were collected from March through June 2011. Results: Use of the web portal was found to improve attitudes towards searching for health information. This variable was identified as the most important predictor of intention to search in both samples. Participants considered the web portal to have good usability, usefulness, and credibility. The intervention group showed slight increases in the use of evidencebased information, critical appraisal skills, and participation compared to the group receiving no intervention, but these differences were not statistically significant. Conclusion: Despite the fact that the study was underpowered, we found that the web portal may have a positive effect on attitudes towards searching for health information. Furthermore, participants considered the web portal to be a relevant tool. It is important to continue experimenting with web-based resources in order to increase user participation in health care decision-making. Trial Registration: ClinicalTrials.gov NCT0126679