Boundary integral method for quantum billiards in a constant magnetic field

We derive a boundary integral equation to compute the eigenvalues of two-dimensional billiards subjected to a magnetic field. The integral requires the Green's function of the boundary-free problem with the magnetic field pointing in the opposite direction. This Green's function is computed for the case of a constant magnetic field perpendicular to the billiard and some applications ate discussed. The elliptical billiard is then studied numerically as an example of a nontrivial application.551A657

A Role for Antimicrobial Stewardship in Clinical Sepsis Pathways: A Prospective Interventional Study

© 2017 by The Society for Healthcare Epidemiology of America. All rights reserved. OBJECTIVE To evaluate the impact of early infectious diseases (ID) antimicrobial stewardship (AMS) intervention on inpatient sepsis antibiotic management. DESIGN Interventional, nonrandomized, controlled study. SETTING Tertiary-care referral hospital, Sydney, Australia. PATIENTS Consecutive, adult, non-intensive care unit (non-ICU) inpatients triggering an institutional clinical sepsis pathway from May to August 2015. INTERVENTION All patients reviewed by an ID Fellow within 24 hours of sepsis pathway trigger underwent case review and clinic file documentation of recommendations. Those not reviewed by an ID Fellow were considered controls and received standard sepsis pathway care. The primary outcome was antibiotic appropriateness 48 hours after sepsis trigger. RESULTS In total, 164 patients triggered the sepsis pathway: 6 patients were excluded (previous sepsis trigger); 158 patients were eligible; 106 had ID intervention; and 52 were control cases. Of these 158 patients, 91 (58%) had sepsis, and 15 of these 158 (9.5%) had severe sepsis. Initial antibiotic appropriateness, assessable in 152 of 158 patients, was appropriate in 80 (53%) of these 152 patients and inappropriate in 72 (47%) of these patients. In the intervention arm, 93% of ID Fellow recommendations were followed or partially followed, including 53% of cases in which antibiotics were de-escalated. ID Fellow intervention improved antibiotic appropriateness at 48 hours by 24% (adjusted risk ratio, 1.24; 95% confidence interval, 1.04-1.47; P=.035). The appropriateness agreement among 3 blinded ID staff opinions was 95%. Differences in intervention and control group mortality (13% vs 17%) and median length of stay (13 vs 17.5 days) were not statistically significant. CONCLUSION Sepsis overdiagnosis and delayed antibiotic optimization may reduce sepsis pathway effectiveness. Early ID AMS improved antibiotic management of non-ICU inpatients with suspected sepsis, predominantly by de-escalation. Further studies are needed to evaluate clinical outcomes. Infect Control Hosp Epidemiol 2017;38:1032-1038

Cyclin D1 overexpression supports stable EBV infection in nasopharyngeal epithelial cells

Undifferentiated nasopharyngeal carcinomas (NPCs) are commonly present with latent EBV infection. However, events regulating EBV infection at early stages of the disease and the role of EBV in disease pathogenesis are largely undefined. Genetic alterations leading to activation of cyclin D1 signaling in premalignant nasopharyngeal epithelial (NPE) cells have been postulated to predispose cells to EBV infection. We previously reported that loss of p16, a negative regulator of cyclin D1 signaling, is a frequent feature of NPC tumors. Here, we report that early premalignant lesions of nasopharyngeal epithelium overexpress cyclin D1. Furthermore, overexpression of cyclin D1 is closely associated with EBV infection. Therefore we investigated the potential role of cyclin D1 overexpression in dysplastic NPE cells in vitro. In human telomerase reverse transcriptase-immortalized NPE cells, overexpression of cyclin D1 or a p16-resistant form of CDK4 (CDK4(R24C)) suppressed differentiation. This suppression may have implications for the close association of EBV infection with undifferentiated NPC. In these in vitro models, we found that cellular growth arrest and senescence occurred in EBV-infected cell populations immediately after infection. Nevertheless, overexpression of cyclin D1 or a p16-resistant form of CDK4 or knockdown of p16 in the human telomerase reverse transcriptase-immortalized NPE cell lines could counteract the EBV-induced growth arrest and senescence. We conclude that dysregulated expression of cyclin D1 in NPE cells may contribute to NPC pathogenesis by enabling persistent infection of EBV.published_or_final_versio

Predictors of Antibiotics Co-prescription with Antimalarials for Patients Presenting with Fever in Rural Tanzania.

Successful implementation of malaria treatment policy depends on the prescription practices for patients with malaria. This paper describes prescription patterns and assesses factors associated with co-prescription of antibiotics and artemether-lumefantrine (AL) for patients presenting with fever in rural Tanzania. From June 2009 to September 2011, a cohort event monitoring program was conducted among all patients treated at 8 selected health facilities in Ifakara and Rufiji Health and Demographic Surveillance System (HDSS).It included all patients presenting with fever and prescribed with AL. Logistic regression was used to model the predictors on the outcome variable which is co-prescription of AL and antibiotics on a single clinical visit. A cohort of 11,648 was recruited and followed up with 92% presenting with fever. Presumptive treatment was used in 56% of patients treated with AL. On average 2.4 (1 -- 7) drugs was prescribed per encounter, indicating co-prescription of AL with other drugs. Children under five had higher odds of AL and antibiotics co-prescription (OR = 0.63, 95% CI: 0.46 -- 0.85) than those aged more than five years. Patients testing negative had higher odds (OR = 2.22, 95%CI: 1.65 -- 2.97) of AL and antibiotics co-prescription. Patients receiving treatment from dispensaries had higher odds (OR = 1.45, 95% CI: 0.84 -- 2.30) of AL and antibiotics co-prescription than those from served in health centres even though the deference was not statistically significant. Regardless the fact that Malaria is declining but due to lack of laboratories and mRDT in most health facilities in the rural areas, clinicians are still treating malaria presumptively. This leads them to prescribe more drugs to treat all possibilities

Neural Decision Boundaries for Maximal Information Transmission

We consider here how to separate multidimensional signals into two categories, such that the binary decision transmits the maximum possible information transmitted about those signals. Our motivation comes from the nervous system, where neurons process multidimensional signals into a binary sequence of responses (spikes). In a small noise limit, we derive a general equation for the decision boundary that locally relates its curvature to the probability distribution of inputs. We show that for Gaussian inputs the optimal boundaries are planar, but for non-Gaussian inputs the curvature is nonzero. As an example, we consider exponentially distributed inputs, which are known to approximate a variety of signals from natural environment.Comment: 5 pages, 3 figure

Acute ECG ST-segment elevation mimicking myocardial infarction in a patient with pulmonary embolism

Pulmonary embolism is a common cardiovascular emergency, but it is still often misdiagnosed due to its unspecific clinical symptoms. Elevated troponin concentrations are associated with greater morbidity and mortality in patients with pulmonary embolism. Right ventricular ischemia due to increased right ventricular afterload is believed to be underlying mechanism of elevated troponin values in acute pulmonary embolism, but a paradoxical coronary artery embolism through opened intra-artrial communication is another possible explanation as shown in our case report

Enzyme immobilisation on amino-functionalised multi-walled carbon nanotubes : structural and biocatalytic characterisation

BACKGROUND: The aim of this work is to investigate the structure and function of enzymes immobilised on nanomaterials. This work will allow better understanding of enzyme-nanomaterial interactions, as well as designing functional protein-nanomaterial conjugates. METHODOLOGY/PRINCIPAL FINDINGS: Multiwalled carbon nanotubes (MWNTs) were functionalised with amino groups to improve solubility and biocompatibility. The pristine and functionalised forms of MWNTs were characterised with Fourier-transform infrared spectroscopy. Thermogravimetric analysis was done to examine the degree of the functionalisation process. An immobilised biocatalyst was prepared on functionalised nanomaterial by covalent binding. Thermomyces lanuginosus lipase was used as a model enzyme. The structural change of the immobilised and free lipases were characterised with transmission electron Microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and Circular dichroism spectroscopy. Biochemical characterisation of immobilised enzyme showed broader pH and thermal optima compared to soluble form. Reusability of the immobilised enzyme for hydrolysis of long chain esters was demonstrated up to ten cycles. CONCLUSION/SIGNIFICANCE: Lipase immobilised on MWNTs has exhibited significantly improved thermal stability. The exploration of advanced nanomaterial for enzyme immobilisation support using sophisticated techniques makes nanobiocatalyst of potential interest for biosensor applications

Aharonov-Bohm interferences from local deformations in graphene

One of the most interesting aspects of graphene is the tied relation between structural and electronic properties. The observation of ripples in the graphene samples both free standing and on a substrate has given rise to a very active investigation around the membrane-like properties of graphene and the origin of the ripples remains as one of the most interesting open problems in the system. The interplay of structural and electronic properties is successfully described by the modelling of curvature and elastic deformations by fictitious gauge fields that have become an ex- perimental reality after the suggestion that Landau levels can form associated to strain in graphene and the subsequent experimental confirmation. Here we propose a device to detect microstresses in graphene based on a scanning-tunneling-microscopy setup able to measure Aharonov-Bohm inter- ferences at the nanometer scale. The interferences to be observed in the local density of states are created by the fictitious magnetic field associated to elastic deformations of the sample.Comment: Some bugs fixe

Diagnostic performance of tuberculosis-specific IgG antibody profiles in patients with presumptive tuberculosis from two continents

Background. Development of rapid diagnostic tests for tuberculosis is a global priority. A  whole proteome screen identified Mycobacterium tuberculosis antigens associated with serological responses in tuberculosis patients. We used World Health Organization (WHO) target product profile (TPP) criteria for a detection test and triage test to evaluate these antigens. Methods. Consecutive patients presenting to microscopy centers and district hospitals in Peru and to outpatient clinics at a tuberculosis reference center in Vietnam were recruited. We tested blood samples from 755 HIV–uninfected adults with presumptive pulmonary tuberculosis to measure IgG antibody responses to 57 M. tuberculosis antigens using a field-based multiplexed serological assay and a 132-antigen bead-based reference assay. We evaluated single antigen performance and models of all possible 3-antigen combinations and multiantigen combinations. Results. Three-antigen and multiantigen models performed similarly and were superior to single antigens. With specificity set at 90% for a detection test, the best sensitivity of a 3-antigen model was 35% (95% confidence interval [CI], 31–40). With sensitivity set at 85% for a triage test, the specificity of the best 3-antigen model was 34% (95% CI, 29–40). The reference assay also did not meet study targets. Antigen performance differed significantly between the study sites for 7/22 of the best-performing antigens. Conclusions. Although M. tuberculosis antigens were recognized by the IgG response during tuberculosis, no single antigen or multiantigen set performance approached WHO TPP criteria for clinical utility among HIV-uninfected adults with presumed tuberculosis in high-volume, urban settings in tuberculosis-endemic countries

Rampant gene rearrangement and haplotype hypervariation among nematode mitochondrial genomes

Rare syntenic conservation, sequence duplication, and the use of both DNA strands to encode genes are signature architectural features defining mitochondrial genomes of enoplean nematodes. These characteristics stand in contrast to the more conserved mitochondrial genome sizes and transcriptional organizations of mitochondrial DNAs (mtDNAs) derived from chromadorean nematodes. To address the frequency of gene rearrangement within nematode mitochondrial DNA (mtDNA), mitochondrial genome variation has been characterized within a more confined enoplean taxonomic unit, the family Mermithidae. The complete nucleotide sequences of the mosquito parasitic nematodes Romanomermis culicivorax, R. nielseni, and R. iyengari mtDNA have been determined. Duplicated expanses encompassing different regions of the mitochondrial genomes were found in each of these congeners. These mtDNA shared few rRNA and protein gene junctions, indicating extensive gene rearrangement within the Romanomermis lineage. Rapid structural changes are also observed at the conspecific level where no two individual nematodes carry the same haplotype. Rolling circle amplification was used to isolate complete mitochondrial genomes from individuals in local populations of Thaumamermis cosgrovei, a parasite of terrestrial isopods. Mitochondrial DNA length variants ranging from 19 to 34 kb are observed, but haplotypes are not shared between any two individuals. The complete nucleotide sequences of three haplotypes have been determined, revealing a constant region encoding most mitochondrial genes and a hypervariable segment that contains intact and pseudogene copies of several mitochondrial genes, duplicated to different copy numbers, resulting in mtDNA size variation. Constant rearrangement generates new T. cosgrovei mtDNA forms