Nonlinear dynamics of a particle in an electric and magnetic field

This work involves the computational study of a charged particle (electron) in the field of a heavy particle (proton) and an applied constant magnetic field. When either the magnetic field or the central field of the proton are switched off , closed analytic solutions for the classical dynamics exist. However, when both fields are present, only approximate analytic solutions are available. For a weak, applied magnetic field perturbation theory may be used to construct the approximate solutions, but these solutions break down in the high field regime. To study the behavior of such an atom in this region we perform numerical studies of the classical dynamics. The nonlinear terms in the equations of motion induce chaotic motions, and such effects will be explored in detail

Advances in the biology, diagnosis and host-pathogen interactions of parvovirus B19

Increased recognition of parvovirus B19(B19), an erythrovirus, as a significant human pathogen that causes fetal loss and severe disease in immunocompromised patients has resulted in intensive efforts to understand the pathogenesis of B19-related disease, to improve diagnostic strategy that is deployed to detect B19 infection and blood-product contamination and, finally, to elucidate the nature of the cellular immune response that is elicited by the virus in diverse patient cohorts. It is becoming clear that at least three related erythrovirus strains (B19, A6/K71 and V9) are circulating in the general population and that viral entry into target cells is mediated by an expanding range of cellular receptors, including P antigen and -integrins. Persistent infection by B19 is emerging as a contributory factor in autoimmune disease, a hypothesis that is constrained by the detection of B19 in the skin of apparently healthy individuals. B19 infection during pregnancy may account for thousands of incidences of fetal loss per annum in Europe, North America and beyond, yet there is currently only minimal screening of pregnant women to assess serological status, and thereby risk of infection, upon becoming pregnant. Whilst major advances in diagnosis of B19 infection have taken place, including standardization of serological and DNA-based detection methodologies, blood donations that are targeted at high-risk groups are only beginning to be screened for B19 IgG and DNAas a means of minimizing exposure of at-risk patients to the virus. It is now firmly established that a Th1-mediated cellular immune response is mounted in immunocompetent individuals, a finding that should contribute to the development of an effective vaccine to prevent B19 infection in selected high-risk groups, including sickle-cell anaemics

Guns and Voting: How to Protect Elections after Bruen

With more guns and more political polarization and violence, states need strong laws to limit risk. In Bruen, the Supreme Court recognized that prohibitions on guns in "sensitive places" — and specifically in "polling places" — were "presumptively lawful." Yet today only 12 states and Washington, DC, prohibit both open and concealed carry of firearms at poll sites. Ironically, the states with the strongest gun regulations — which had restricted the ability to carry guns in public generally, rather than prohibiting guns in particular locations — were made most vulnerable in the wake of Bruen. In fact, only one of the six states that had their laws struck down by the decision specifically prohibited guns in polling places at the time of the decision.Now these states that once had strong general gun laws must scramble to enact new protections for elections. Although some states have banned guns at polling placessince Bruen, there is far more work to do.This report evaluates the new risks that gun violence poses for U.S. elections and proposes policy solutions to limit those risks. Solutions include prohibitions on firearms wherever voting or election administration occurs — at or near polling places, ballot drop boxes, election offices, and ballot counting facilities. In addition, states need stronger laws preventing intimidation of voters, election officials, election workers, and anyone else facilitating voting, with express recognition of the role that guns play in intimidation.Brennan Center for Justice: http://brennancenter.org/Giffords Law Center to Prevent Gun Violence: https://giffords.org/lawcenter/gun-laws/

Paravovirus B19 infection - an underestimated problem

Abstract included in text

Λ\Lambda-Enhanced Imaging of Molecules in an Optical Trap

We report non-destructive imaging of optically trapped calcium monofluoride (CaF) molecules using in-situ $\Lambda$-enhanced gray molasses cooling. $200$ times more fluorescence is obtained compared to destructive on-resonance imaging, and the trapped molecules remain at a temperature of $20\,\mu\text{K}$. The achieved number of scattered photons makes possible non-destructive single-shot detection of single molecules with high fidelity.Comment: 6 pages, 4 figure

An Optical Tweezer Array of Ultracold Molecules

Arrays of single ultracold molecules promise to be a powerful platform for many applications ranging from quantum simulation to precision measurement. Here we report on the creation of an optical tweezer array of single ultracold CaF molecules. By utilizing light-induced collisions during the laser cooling process, we trap single molecules. The high densities attained inside the tweezer traps have also enabled us to observe in the absence of light molecule-molecule collisions of laser cooled molecules for the first time

Biomarker responses to weaning stress in beef calves

The study objective was to investigate the physiological effects of weaning on beef calves and identify a panel of blood-based welfare biomarkers. On the day (d) of weaning (d 0), 16 spring-born, singlesuckled, beef bull calves that previously grazed with their dams at pasture, were assigned to one of two treatments: (1) control (n = 8), calves were loose-housed with their dam, (2) weaned (n = 8), calves were abruptly separated from their dam and loose-housed. Jugular blood was collected on d −4, 0, 1, 2, 3, 7, and 14 relative to weaning (d 0) and assayed for inflammatory and steroid variables. Total leukocyte counts were measured in whole blood. It is concluded that neutrophil number is a robust biomarker of stress and that plasma CXCL8 is a sensitive indicator of stress in weaned and control calves. In future studies, these two biomarkers should be central to the characterisation of stress responses