Estimating the effect of healthcare-associated infections on excess length of hospital stay using inverse probability-weighted survival curves

Background: Studies estimating excess length of stay (LOS) attributable to nosocomial infections have failed to address time-varying confounding, likely leading to overestimation of their impact. We present a methodology based on inverse probability–weighted survival curves to address this limitation. Methods: A case study focusing on intensive care unit–acquired bacteremia using data from 2 general intensive care units (ICUs) from 2 London teaching hospitals were used to illustrate the methodology. The area under the curve of a conventional Kaplan-Meier curve applied to the observed data was compared with that of an inverse probability–weighted Kaplan-Meier curve applied after treating bacteremia as censoring events. Weights were based on the daily probability of acquiring bacteremia. The difference between the observed average LOS and the average LOS that would be observed if all bacteremia cases could be prevented was multiplied by the number of admitted patients to obtain the total excess LOS. Results: The estimated total number of extra ICU days caused by 666 bacteremia cases was estimated at 2453 (95% confidence interval [CI], 1803–3103) days. The excess number of days was overestimated when ignoring time-varying confounding (2845 [95% CI, 2276–3415]) or when completely ignoring confounding (2838 [95% CI, 2101–3575]). Conclusions: ICU-acquired bacteremia was associated with a substantial excess LOS. Wider adoption of inverse probability–weighted survival curves or alternative techniques that address time-varying confounding could lead to better informed decision making around nosocomial infections and other time-dependent exposures

On sets of irreducible polynomials closed by composition

Let $\mathcal S$ be a set of monic degree $2$ polynomials over a finite field and let $C$ be the compositional semigroup generated by $\mathcal S$. In this paper we establish a necessary and sufficient condition for $C$ to be consisting entirely of irreducible polynomials. The condition we deduce depends on the finite data encoded in a certain graph uniquely determined by the generating set $\mathcal S$. Using this machinery we are able both to show examples of semigroups of irreducible polynomials generated by two degree $2$ polynomials and to give some non-existence results for some of these sets in infinitely many prime fields satisfying certain arithmetic conditions

A novel multiplex PCR system for the detection of virulence associated genes of E. coli O157:H7 from food system

In view of the importance E. coli serotype 0157:H7 in human diseases, an easy and quick system is desirable to detect toxin producing strains. In this report, we describe standardization of a novel multiplex Polymerase Chain Reaction (mPCR) assay for simultaneous detection of four important genes associated with the organism E. coli 0157:H7 viz., stx 1, stx 2, eae A, hly A along with an internal amplification control (IAC). The mPCR method developed in the present study is sensitive enough to detect cells as low as 103 CFU ml-1 or g-1 of the food samples. The E. coli 0157:H7 strains having been identified to contain the gene in the mPCR were unequivocally detected positive for the serological and conventional culture method.  As E. coli 0157:H7 is qualified as biowarfare agent; this mPCR system is of immense help in detecting them during emergencies of biological war and suspected outbreaks.&nbsp

Association of thyroid status with hemoglobin levels in pregnancy

Background: The association of hemoglobin levels with thyroid status in pregnancy was not studied in detail. Therefore, in this study, we assessed the levels of hemoglobin, thyroid function and its association with hemoglobin levels in first trimester of pregnancy.Methods: Fifty pregnant women who didn’t start any supplementation were recruited from the obstetrics and gynecology outpatient department. Fifty age matched controls were recruited from the residents and staff of the hospital.  Thyroid profile and hemoglobin levels were measured in both the groups. The association was seen between hemoglobin levels and thyroid stimulating hormone (TSH) levels.Results: The hemoglobin levels are significantly low in first trimester pregnant women. Further, the increased TSH levels are negatively correlated with low hemoglobin levels.Conclusions: Screening of hemoglobin levels in first trimester itself will be beneficial to prevent the complications of pregnancy. Further, hypothyroidism also present and associated with reduced hemoglobin. So, early diagnosis of these deficiencies will be useful to start giving supplements to avoid unwanted effects in pregnancy

Features of the fluctuation -electromagnetic interaction between a small conducting particle and polarizable medium

For the first time, new important features of the fluctuation electromagnetic interaction between a small conducting particle and a smooth surface of polarizable medium (both dielectric and metallic) are worked out. The particle is characterized by classical electric and magnetic polarizabilities. The temperature dependence and retardation effects are explicitly taken into account. The resulting interaction force between a metallic particle and the surface of metal proves to be determined to great extent by magnetic coupling and reveals specific dependences on distance, temperature, particle radius and material properties of contacting materials. Numerical estimations are given in the case of a Cu particle above a smooth Cu substrate at different particle radius and temperature of the system.Comment: 13 pages, 5 figure

Equivariant map superalgebras

Suppose a group $\Gamma$ acts on a scheme $X$ and a Lie superalgebra $\mathfrak{g}$. The corresponding equivariant map superalgebra is the Lie superalgebra of equivariant regular maps from $X$ to $\mathfrak{g}$. We classify the irreducible finite dimensional modules for these superalgebras under the assumptions that the coordinate ring of $X$ is finitely generated, $\Gamma$ is finite abelian and acts freely on the rational points of $X$, and $\mathfrak{g}$ is a basic classical Lie superalgebra (or $\mathfrak{sl}(n,n)$, $n > 0$, if $\Gamma$ is trivial). We show that they are all (tensor products of) generalized evaluation modules and are parameterized by a certain set of equivariant finitely supported maps defined on $X$. Furthermore, in the case that the even part of $\mathfrak{g}$ is semisimple, we show that all such modules are in fact (tensor products of) evaluation modules. On the other hand, if the even part of $\mathfrak{g}$ is not semisimple (more generally, if $\mathfrak{g}$ is of type I), we introduce a natural generalization of Kac modules and show that all irreducible finite dimensional modules are quotients of these. As a special case, our results give the first classification of the irreducible finite dimensional modules for twisted loop superalgebras.Comment: 27 pages. v2: Section numbering changed to match published version. Other minor corrections. v3: Minor corrections (see change log at end of introduction

Our experience of management of sub trochanteric fractures of femur by proximal femoral nail

Background: Sub trochanteric fractures of the femur remain some of the most challenging fractures. Most of the fractures result from trivial fall in the elderly; while in the younger age group, it's mainly due to road traffic accidents. Operative management is the preferred treatment. This study is intended to assess the outcome of the intramedullary fixation of sub trochanteric fractures with Proximal Femoral Nail (PFN).Methods: This study is a prospective, uncontrolled study of 40 cases of sub trochanteric fracture of femur admitted to a tertiary level hospital between August 2011 and November 2013; and treated with proximal femoral nails. Adults with recent sub trochanteric fracture of femur were included in this study; while patients less than eighteen years of age, pathologic fractures, periprosthetic fractures, and old neglected fractures were excluded from the study.  Results: In our study of 40 cases, there were 28 male and 12 female patients with mean age of 51.43 years (range 22-87 years). Based on Seinsheimer’s classification, type IIIA fractures accounted for majority (32.5%) of the cases. majority of patients, i.e. 35% (n=14) showed union at 20 weeks after surgery. Cases were followed up and assessed according to the Harris hip scoring system (Modified).The outcome was good to excellent in 82.9% cases.  Conclusions: From our study we conclude that PFN is a reliable minimally invasive implant for sub trochanteric fractures, with good to excellent functional outcome in the majority of cases.