Simulating `Complex' Problems with Quantum Monte Carlo

We present a new quantum Monte Carlo algorithm suitable for generically complex problems, such as systems coupled to external magnetic fields or anyons in two spatial dimensions. We find that the choice of gauge plays a nontrivial role, and can be used to reduce statistical noise in the simulation. Furthermore, it is found that noise can be greatly reduced by approximate cancellations between the phases of the (gauge dependent) statistical flux and the external magnetic flux.Comment: Revtex, 11 pages. 3 postscript files for figures attache

Evaporation, seepage and water quality management in storage dams: a review of research methods

One of the most significant sources of water wastage in Australia is loss from small storage dams, either by seepage or evaporation. Over much of Australia, evaporative demand routinely exceeds precipitation. This paper outlines first, methodologies and measurement techniques to quantify the rate of evaporative loss from fresh water storages. These encompass high-accuracy water balance monitoring; determination of the validity of alternative estimation equations, in particular the FAO56 Penman- Monteith ETo methodology; and the commencement of CFD modeling to determine a 'dam factor' in relation to practical atmospheric measurement techniques. Second, because the application of chemical monolayers is the only feasible alternative to the high cost of physically covering the storages to retard evaporation, the use of cetyl alcohol-based monolayers is reviewed, and preliminary research on their degradation by photolytic action, by wind break-up and by microbial degradation reported. Similarly, preliminary research on monolayer visualisation techniques for field application is reported; and potential enhancement of monolayers by other chemicals and attendant water quality issues are considered

Simulation of metallic nanostructures for emission of THz radiation using the lateral photo-Dember effect

A 2D simulation for the lateral photo-Dember effect is used to calculate the THz emission of metallic nanostructures due to ultrafast diffusion of carriers in order to realize a series of THz emitters.Comment: Corrected version of a paper given at 2011 36th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz

Evaluation of environmental scanning electron microscopy for analysis of Proteus mirabilis crystalline biofilms in situ on urinary catheters

Proteus mirabilis is a common cause of catheter-associated urinary tract infections and frequently leads to blockage of catheters due to crystalline biofilm formation. Scanning electron microscopy (SEM) has proven to be a valuable tool in the study of these unusual biofilms, but entails laborious sample preparation that can introduce artefacts, undermining the investigation of biofilm development. In contrast, environmental scanning electron microscopy (ESEM) permits imaging of unprocessed, fully hydrated samples, which may provide much insight into the development of P. mirabilis biofilms. Here, we evaluate the utility of ESEM for the study of P. mirabilis crystalline biofilms in situ, on urinary catheters. In doing so, we compare this to commonly used conventional SEM approaches for sample preparation and imaging. Overall, ESEM provided excellent resolution of biofilms formed on urinary catheters and revealed structures not observed in standard SEM imaging or previously described in other studies of these biofilms. In addition, we show that energy-dispersive X-ray spectroscopy (EDS) may be employed in conjunction with ESEM to provide information regarding the elemental composition of crystalline structures and demonstrate the potential for ESEM in combination with EDS to constitute a useful tool in exploring the mechanisms underpinning crystalline biofilm formation

Prospective cohort study of procalcitonin levels in children with cancer presenting with febrile neutropenia

BACKGROUND: Febrile neutropenia (FNP) causes significant morbidity and mortality in children undergoing treatment for cancer. The development of clinical decision rules to help stratify risks in paediatric FNP patients and the use of inflammatory biomarkers to identify high risk patients is an area of recent research. This study aimed to assess if procalcitonin (PCT) levels could be used to help diagnose or exclude severe infection in children with cancer who present with febrile neutropenia, both as a single measurement and in addition to previously developed clinical decision rules. METHODS: This prospective cohort study of a diagnostic test included patients between birth and 18 years old admitted with febrile neutropenia to the Paediatric Oncology and Haematology Ward in Leeds between 1(st) October 2012 and 30(th) September 2013. Each admission with FNP was treated as a separate episode. Blood was taken for a procalcitonin level at admission with routine investigations. 'R' was used for statistical analysis. Likelihood ratios were calculated and multivariable logistic regression. RESULTS: Forty-eight episodes from 27 patients were included. PCT >2 ng/dL was strongly associated with increased risk of severe infection (likelihood ratio of 26 [95% CI 3.5, 190]). The data suggests that the clinical decision rules are largely ineffective at risk stratification, frequently over-stating the risk of individual episodes. High procalcitonin levels on admission are correlated with a greatly increased risk of severe infection. CONCLUSIONS: This study does not show a definitive benefit in using PCT in FNP though it supports further research on its use. The benefit of novel biomarkers has not been proven and before introducing new tests for patients it is important their benefit above existing features is proven, particularly due to the increasing importance of health economics

Internet-based medical education: a realist review of what works, for whom and in what circumstances

http://creativecommons.org/licenses/by/2.0

Airborne S-Band SAR for forest biophysical retrieval in temperate mixed forests of the UK

Radar backscatter from forest canopies is related to forest cover, canopy structure and aboveground biomass (AGB). The S-band frequency (3.1–3.3 GHz) lies between the longer L-band (1–2 GHz) and the shorter C-band (5–6 GHz) and has been insufficiently studied for forest applications due to limited data availability. In anticipation of the British built NovaSAR-S satellite mission, this study evaluates the benefits of polarimetric S-band SAR for forest biophysical properties. To understand the scattering mechanisms in forest canopies at S-band the Michigan Microwave Canopy Scattering (MIMICS-I) radiative transfer model was used. S-band backscatter was found to have high sensitivity to the forest canopy characteristics across all polarisations and incidence angles. This sensitivity originates from ground/trunk interaction as the dominant scattering mechanism related to broadleaved species for co-polarised mode and specific incidence angles. The study was carried out in the temperate mixed forest at Savernake Forest and Wytham Woods in southern England, where airborne S-band SAR imagery and field data are available from the recent AirSAR campaign. Field data from the test sites revealed wide ranges of forest parameters, including average canopy height (6–23 m), diameter at breast-height (7–42 cm), basal area (0.2–56 m2/ha), stem density (20–350 trees/ha) and woody biomass density (31–520 t/ha). S-band backscatter-biomass relationships suggest increasing backscatter sensitivity to forest AGB with least error between 90.63 and 99.39 t/ha and coefficient of determination (r2) between 0.42 and 0.47 for the co-polarised channel at 0.25 ha resolution. The conclusion is that S-band SAR data such as from NovaSAR-S is suitable for monitoring forest aboveground biomass less than 100 t/ha at 25 m resolution in low to medium incidence angle rang

Rasgrp1 mutation increases naïve T-cell CD44 expression and drives mTOR-dependent accumulation of Helios+ T cells and autoantibodies

Missense variants are a major source of human genetic variation. Here we analyze a new mouse missense variant, Rasgrp1Anaef, with an ENU-mutated EF hand in the Rasgrp1 Ras guanine nucleotide exchange factor. Rasgrp1Anaef mice exhibit anti-nuclear autoantibodies and gradually accumulate a CD44hi Helios+ PD-1+ CD4+ T cell population that is dependent on B cells. Despite reduced Rasgrp1-Ras-ERK activation in vitro, thymocyte selection in Rasgrp1Anaef is mostly normal in vivo, although CD44 is overexpressed on naïve thymocytes and T cells in a T-cell-autonomous manner. We identify CD44 expression as a sensitive reporter of tonic mTOR-S6 kinase signaling through a novel mouse strain, chino, with a reduction-of-function mutation in Mtor. Elevated tonic mTOR-S6 signaling occurs in Rasgrp1Anaef naïve CD4+ T cells. CD44 expression, CD4+ T cell subset ratios and serum autoantibodies all returned to normal in Rasgrp1AnaefMtorchino double-mutant mice, demonstrating that increased mTOR activity is essential for the Rasgrp1Anaef T cell dysregulation

Rasgrp1 mutation increases naïve T-cell CD44 expression and drives mTOR-dependent accumulation of Helios⁺ T cells and autoantibodies

Missense variants are a major source of human genetic variation. Here we analyze a new mouse missense variant, Rasgrp1ᴬⁿᵃᵉᶠ, with an ENU-mutated EF hand in the Rasgrp1 Ras guanine nucleotide exchange factor. Rasgrp1ᴬⁿᵃᵉᶠ mice exhibit anti-nuclear autoantibodies and gradually accumulate a CD44hi Helios⁺ PD-1⁺ CD4⁺ T cell population that is dependent on B cells. Despite reduced Rasgrp1-Ras-ERK activation in vitro, thymocyte selection in Rasgrp1ᴬⁿᵃᵉᶠ is mostly normal in vivo, although CD44 is overexpressed on naïve thymocytes and T cells in a T-cell-autonomous manner. We identify CD44 expression as a sensitive reporter of tonic mTOR-S6 kinase signaling through a novel mouse strain, chino, with a reduction-of-function mutation in Mtor. Elevated tonic mTOR-S6 signaling occurs in Rasgrp1ᴬⁿᵃᵉᶠ naïve CD4⁺ T cells. CD44 expression, CD4⁺ T cell subset ratios and serum autoantibodies all returned to normal in Rasgrp1ᴬⁿᵃᵉᶠMtorᶜʰⁱⁿᵒ double-mutant mice, demonstrating that increased mTOR activity is essential for the Rasgrp1ᴬⁿᵃᵉᶠ T cell dysregulation

Subduction factory: 4. Depth‐dependent flux of H 2 O from subducting slabs worldwide

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95328/1/jgrb16727.pd