Sensitivity-analysis method for inverse simulation application

An important criticism of traditional methods of inverse simulation that are based on the Newton–Raphson algorithm is that they suffer from numerical problems. In this paper these problems are discussed and a new method based on sensitivity-analysis theory is developed and evaluated. The Jacobian matrix may be calculated by solving a sensitivity equation and this has advantages over the approximation methods that are usually applied when the derivatives of output variables with respect to inputs cannot be found analytically. The methodology also overcomes problems of input-output redundancy that arise in the traditional approaches to inverse simulation. The sensitivity- analysis approach makes full use of information within the time interval over which key quantities are compared, such as the difference between calculated values and the given ideal maneuver after each integration step. Applications to nonlinear HS125 aircraft and Lynx helicopter models show that, for this sensitivity-analysis method, more stable and accurate results are obtained than from use of the traditional Newton–Raphson approach

Folding model analysis of alpha radioactivity

Radioactive decay of nuclei via emission of $\alpha$ particles has been studied theoretically in the framework of a superasymmetric fission model using the double folding (DF) procedure for obtaining the $\alpha$-nucleus interaction potential. The DF nuclear potential has been obtained by folding in the density distribution functions of the $\alpha$ nucleus and the daughter nucleus with a realistic effective interaction. The M3Y effective interaction has been used for calculating the nuclear interaction potential which has been supplemented by a zero-range pseudo-potential for exchange along with the density dependence. The nuclear microscopic $\alpha$-nucleus potential thus obtained has been used along with the Coulomb interaction potential to calculate the action integral within the WKB approximation. This subsequently yields microscopic calculations for the half lives of $\alpha$ decays of nuclei. The density dependence and the exchange effects have not been found to be very significant. These calculations provide reasonable estimates for the lifetimes of $\alpha$ radioactivity of nuclei.Comment: 7 pages including 1 figur

Searching for keV Sterile Neutrino Dark Matter with X-ray Microcalorimeter Sounding Rockets

High-resolution X-ray spectrometers onboard suborbital sounding rockets can search for dark matter candidates that produce X-ray lines, such as decaying keV-scale sterile neutrinos. Even with exposure times and effective areas far smaller than XMM-Newton and Chandra observations, high-resolution, wide field-of-view observations with sounding rockets have competitive sensitivity to decaying sterile neutrinos. We analyze a subset of the 2011 observation by the X-ray Quantum Calorimeter instrument centered on Galactic coordinates l = 165, b = -5 with an effective exposure of 106 seconds, obtaining a limit on the sterile neutrino mixing angle of sin^2(2 theta) < 7.2e-10 at 95% CL for a 7 keV neutrino. Better sensitivity at the level of sin^2(2 theta) ~ 2.1e-11 at 95\% CL for a 7 keV neutrino is achievable with future 300-second observations of the galactic center by the Micro-X instrument, providing a definitive test of the sterile neutrino interpretation of the reported 3.56 keV excess from galaxy clusters.Comment: 13 pages, 13 figures, submitted to Ap

Radioactive decays at limits of nuclear stability

The last decades brought an impressive progress in synthesizing and studying properties of nuclides located very far from the beta stability line. Among the most fundamental properties of such exotic nuclides, usually established first, is the half-life, possible radioactive decay modes, and their relative probabilities. When approaching limits of nuclear stability, new decay modes set in. First, beta decays become accompanied by emission of nucleons from highly excited states of daughter nuclei. Second, when the nucleon separation energy becomes negative, nucleons start to be emitted from the ground state. Here, we present a review of the decay modes occurring close to the limits of stability. The experimental methods used to produce, identify and detect new species and their radiation are discussed. The current theoretical understanding of these decay processes is overviewed. The theoretical description of the most recently discovered and most complex radioactive process - the two-proton radioactivity - is discussed in more detail.Comment: Review, 68 pages, 39 figure

Theoretical Study of Fluid Membranes of Spherical Topology with Internal Degrees of Freedom

A theoretical study of vesicles of topological genus zero is presented. The bilayer membranes forming the vesicles have various degrees of intrinsic (tangent-plane) orientational order, ranging from smectic to hexatic, frustrated by curvature and topology. The field-theoretical model for these `$n$-atic' surfaces has been studied before in the low temperature (mean-field) limit. Work presented here includes the effects of thermal fluctuations. Using the lowest Landau level approximation, the coupling between order and shape is cast in a simple form, facilitating insights into the behaviour of vesicles. The order parameter contains vortices, whose effective interaction potential is found, and renormalized by membrane fluctuations. The shape of the phase space has a counter-intuitive influence on this potential. A criterion is established whereby a vesicle of finite rigidity may be burst by its own in-plane order, and an analogy is drawn with flux exclusion from a type-I superconductor.Comment: 34 pages + 4 Postscript figures. Uses RevTe

Photography as an act of collaboration

The camera is usually considered to be a passive tool under the control of the operator. This definition implicitly constrains how we use the medium, as well as how we look at – and what we see in – its interpretations of scenes, objects, events and ‘moments’. This text will suggest another way of thinking about – and using – the photographic medium. Based on the evidence of photographic practice (mine and others’), I will suggest that, as a result of the ways in which the medium interprets, juxtaposes and renders the elements in front of the lens, the camera is capable of depicting scenes, events and moments that did not exist and could not have existed until brought into being by the act of photographing them. Accordingly, I will propose that the affective power of many photographs is inseparable from their ‘photographicness’ – and that the photographic medium should therefore be considered as an active collaborator in the creation of uniquely photographic images

Genomic insights into the rapid emergence and evolution of MDR in Staphylococcus pseudintermedius.

OBJECTIVES: MDR methicillin-resistant Staphylococcus pseudintermedius (MRSP) strains have emerged rapidly as major canine pathogens and present serious treatment issues and concerns to public health due to their, albeit low, zoonotic potential. A further understanding of the genetics of resistance arising from a broadly susceptible background of S. pseudintermedius is needed. METHODS: We sequenced the genomes of 12 S. pseudintermedius isolates of varied STs and resistance phenotypes. RESULTS: Nine distinct clonal lineages had acquired either staphylococcal cassette chromosome (SCC) mec elements and/or Tn5405-like elements carrying up to five resistance genes [aphA3, sat, aadE, erm(B), dfrG] to generate MRSP, MDR methicillin-susceptible S. pseudintermedius and MDR MRSP populations. The most successful and clinically problematic MDR MRSP clones, ST68 SCCmecV(T) and ST71 SCCmecII-III, have further accumulated mutations in gyrA and grlA conferring resistance to fluoroquinolones. The carriage of additional mobile genetic elements (MGEs) was highly variable, suggesting that horizontal gene transfer is frequent in S. pseudintermedius populations. CONCLUSIONS: Importantly, the data suggest that MDR MRSP evolved rapidly by the acquisition of a very limited number of MGEs and mutations, and that the use of many classes of antimicrobials may co-select for the spread and emergence of MDR and XDR strains. Antimicrobial stewardship will need to be comprehensive, encompassing human medicine and veterinary disciplines to successfully preserve antimicrobial efficacy

Assessing the infection burden and associated risk factors in children under 5 across Jaipurs urban slums: A feasibility study using a One Health approach

Purpose: Infectious diseases are one of the leading causes of death among children under five (U5s) across both India & globally. This is worse in slum environments with poor access to water, sanitation & hygiene (WASH), good nutrition & a safe built environment. / Globally, a One Health (e.g. human, animal & environment) approach is increasingly advocated by WHO, FAO & OIE to reduce infections & antimicrobial resistance. As U5s living in peri-urban slums are exposed to household and community owned companion & livestock animals and pests, the CHIP Consortium hypothesized that utilizing a One Health approach to co-produce behavior change & slum upgrading interventions may reduce this burden where other WASH & nutrition interventions have failed. / This study aimed to assess the feasibility of utilising a One Health approach to assess U5 infection & risk factor prevalence in Jaipurs urban slums prior to undertaking prospective cohort studies involving culture and culture independent sampling of U5s and animals across our study sites in Jaipur, Jakarta & Antofagasta. / Methods: We administered a Rapid Household Survey to 25 purposely selected households across six slums. The questionnaire evaluated infection prevalence, health seeking behaviors, the built environment, presence of animals & pests, and individual to household-level demographics. Associations were calculated using correlations among continuous variables to show strength of significance between continuous variables. / Results: We found a high incidence of infections in children under five at 40%. This was most significantly correlated with accessibility of sanitary toilets (r = .62) and household expenditure. Vaccination coverage and child characteristics (such as size) were minimally correlated, while the presence of animals (pets or pests) was not correlated; the latter was likely due to the design of the survey. / Conclusion: This study found a higher infection prevalence than previous studies. We also found higher correlations with infection incidence among household-level characteristics, indicating that effective interventions need to address both the built and socio-economic environments. A pilot prospective cohort study, which includes researcher observations for the presence of animals to account for inconsistencies in the survey, is now underway

Inpatient COVID-19 mortality has reduced over time: Results from an observational cohort

BACKGROUND: The Covid-19 pandemic in the United Kingdom has seen two waves; the first starting in March 2020 and the second in late October 2020. It is not known whether outcomes for those admitted with severe Covid were different in the first and second waves. METHODS: The study population comprised all patients admitted to a 1,500-bed London Hospital Trust between March 2020 and March 2021, who tested positive for Covid-19 by PCR within 3-days of admissions. Primary outcome was death within 28-days of admission. Socio-demographics (age, sex, ethnicity), hypertension, diabetes, obesity, baseline physiological observations, CRP, neutrophil, chest x-ray abnormality, remdesivir and dexamethasone were incorporated as co-variates. Proportional subhazards models compared mortality risk between wave 1 and wave 2. Cox-proportional hazard model with propensity score adjustment were used to compare mortality in patients prescribed remdesivir and dexamethasone. RESULTS: There were 3,949 COVID-19 admissions, 3,195 hospital discharges and 733 deaths. There were notable differences in age, ethnicity, comorbidities, and admission disease severity between wave 1 and wave 2. Twenty-eight-day mortality was higher during wave 1 (26.1% versus 13.1%). Mortality risk adjusted for co-variates was significantly lower in wave 2 compared to wave 1 [adjSHR 0.49 (0.37, 0.65) p<0.001]. Analysis of treatment impact did not show statistically different effects of remdesivir [HR 0.84 (95%CI 0.65, 1.08), p = 0.17] or dexamethasone [HR 0.97 (95%CI 0.70, 1.35) p = 0.87]. CONCLUSION: There has been substantial improvements in COVID-19 mortality in the second wave, even accounting for demographics, comorbidity, and disease severity. Neither dexamethasone nor remdesivir appeared to be key explanatory factors, although there may be unmeasured confounding present

Improving Efficiency and Quality of the Children’s ASD Diagnostic Pathway: Lessons Learned from Practice

The ‘autism diagnosis crisis’ and long waiting times for assessment are as yet unresolved, leading to undue stress and limiting\ud access to effective support. There is therefore a significant need for evidence to support practitioners in the development of\ud efficient services, delivering acceptable waiting times and effectively meeting guideline standards. This study reports statistically\ud significant reductions in waiting times for autism diagnostic assessment following a children’s health service improvement\ud programme. The average wait between referral and first appointment reduced from 14.2 to 10.4 weeks (t(21) = 4.3,\ud p < 0.05) and between referral and diagnosis shared, reduced from 270 to 122.5 days, (t(20) = 5.5, p < 0.05). The proportion\ud of girls identified increased from 5.6 to 2.7:1. Methods reported include: local improvement action planning; evidence based\ud pathways; systematic clinical data gathering and a training plan. This is a highly significant finding for many health services\ud wrestling with the challenges of demand and capacity for autism diagnosis and assessment