Detection of chemical warfare agent simulants and hydrolysis products in biological samples by paper spray mass spectrometry

Paper spray ionization coupled to a high resolution tandem mass spectrometer (a quadrupole orbitrap) was used to identify and quantitate chemical warfare agent (CWA) simulants and their hydrolysis products in blood and urine. Three CWA simulants, dimethyl methylphosphonate (DMMP), trimethyl phosphate (TMP), and diisopropyl methylphosphonate (DIMP), and their isotopically labeled standards were analyzed in human whole blood and urine. Calibration curves were generated and tested with continuing calibration verification standards. Limits of detection for these three compounds were in the low ng mL−1 range for the direct analysis of both blood and urine samples. Five CWA hydrolysis products, ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA), isobutyl methylphosphonic acid (iBuMPA), cyclohexyl methylphosphonic acid (CHMPA), and pinacolyl methylphosphonic acid (PinMPA), were also analyzed. Calibration curves were generated in both positive and negative ion modes. Limits of detection in the negative ion mode ranged from 0.36 ng mL−1 to 1.25 ng mL−1 in both blood and urine for the hydrolysis products. These levels were well below those found in victims of the Tokyo subway attack of 2 to 135 ng mL−1. Improved stability and robustness of the paper spray technique in the negative ion mode was achieved by the addition of chlorinated solvents. These applications demonstrate that paper spray mass spectrometry (PS-MS) can be used for rapid, sample preparation-free detection of chemical warfare agents and their hydrolysis products at physiologically relevant concentrations in biological samples

Topological effects in ring polymers: A computer simulation study

Unconcatenated, unknotted polymer rings in the melt are subject to strong interactions with neighboring chains due to the presence of topological constraints. We study this by computer simulation using the bond-fluctuation algorithm for chains with up to N=512 statistical segments at a volume fraction \Phi=0.5 and show that rings in the melt are more compact than gaussian chains. A careful finite size analysis of the average ring size R \propto N^{\nu} yields an exponent \nu \approx 0.39 \pm 0.03 in agreement with a Flory-like argument for the topologica interactions. We show (using the same algorithm) that the dynamics of molten rings is similar to that of linear chains of the same mass, confirming recent experimental findings. The diffusion constant varies effectively as D_{N} \propto N^{-1.22(3) and is slightly higher than that of corresponding linear chains. For the ring sizes considered (up to 256 statistical segments) we find only one characteristic time scale \tau_{ee} \propto N^{2.0(2); this is shown by the collapse of several mean-square displacements and correlation functions onto corresponding master curves. Because of the shrunken state of the chain, this scaling is not compatible with simple Rouse motion. It applies for all sizes of ring studied and no sign of a crossover to any entangled regime is found.Comment: 20 Pages,11 eps figures, Late

Reflecting the real value of health care resources in modelling and cost-effectiveness studies-The example of viral load informed differentiated care

BACKGROUND: The WHO HIV Treatment Guidelines suggest routine viral-load monitoring can be used to differentiate antiretroviral therapy (ART) delivery and reduce the frequency of clinic visits for patients stable on ART. This recommendation was informed by economic analysis that showed the approach is very likely to be cost-effective, even in the most resource constrained of settings. The health benefits were shown to be modest but the costs of introducing and scaling up viral load monitoring can be offset by anticipated reductions in the costs of clinic visits, due to these being less frequent for many patients. KEY ISSUES FOR ECONOMIC EVALUATION: The cost-effectiveness of introducing viral-load informed differentiated care depends upon whether cost reductions are possible if the number of clinic visits is reduced and/or how freed clinic capacity is used for alternative priorities. Where freed resources, either physical or financial, generate large health gains (e.g. if committed to patients failing ART or to other high value health care interventions), the benefits of differentiated care are expected to be high; if however these freed physical resources are already under-utilized or financial resources are used less efficiently and would not be put to as beneficial an alternative use, the policy may not be cost-effective. The implication is that the use of conventional unit costs to value resources may not well reflect the latter's value in contributing to health improvement. Analyses intended to inform resource allocated decisions in a number of settings may therefore have to be interpreted with due consideration to local context. In this paper we present methods of how economic analyses can reflect the real value of health care resources rather than simply applying their unit costs. The analyses informing the WHO Guidelines are re-estimated by implementing scenarios using this framework, informing how differentiated care can be prioritized to generate greatest gains in population health. IMPLICATIONS: The findings have important implications for how economic analyses should be undertaken and reported in HIV and other disease areas. Results provide guidance on conditions under which viral load informed differentiated care will more likely prove to be cost effective when implemented

Preparation, structured deliberate practice and decision making in elite level football: The case study of Gary Neville (Manchester United FC and England)

Decision making in elite level sporting competition is often regarded as distinguishing success from failure. As an intricate brain-based process it is unlike other physical processes because it is invisible and is typically only evidenced after the event. This case study shows how an individual achieved great success in elite level professional football through consistent positive decision making on and off the field of play. Through prolonged interviewing, Gary Neville, a player from Manchester United Football Club, explored personal behaviours, the structure and activities of deliberate practice and his professional choices in match preparation. His career-long devotion to purposeful organised practice was focused on cognition, physical preparation, context-relative physical action and refined repetition to optimise his mental comfort while enhancing his match day performances. This approach was underpinned by diligent personal and collective organisation and by concerted action. Results provide an insight into the categorical nature of his deliberate practice, sport-specific information processing and match-based decision making. At the operational level, his process was mediated by a complex mental representation of ongoing and anticipated game situations; these representations were continuously updated during each match. Allowing for the limitations of the design, implications are provided for developmental and educational coaching, match preparation, deliberate practice activity and improved use of the performance analysis software packages in professional football

Qualitative perspectives on how Manchester United Football Club developed and sustained serial winning

Talent development in sport is well represented in scientific literature. Yet, the drive to protect ‘trade secrets’ often means that access to these high performing groups is rare, especially as these high level performances are being delivered. This leaves the details of high-end working practices absent from current academic commentary. As a result, clubs interested in developing excellent practice are left to build on personal initiative and insight and/or custom-and-practice, which is unlikely to yield successful outcomes. To address this shortfall the current study reports on prolonged engagement with a single high performing club, considering how their practice corresponds with existing sport talent development models. The paper ends by proposing an evidence-based, football-specific model for talent development, maintained high level performance and serial winning. This model emphasises four dominant features: culture, behavioral characteristics, practice engagement and the managing and guiding of performance ‘potential’. The study provides insights into the visceral reality of daily experiences across the life course of professional soccer, while advancing the evidence-base for understanding how Manchester United achieved their serial success

Computer Simulations of Supercooled Liquids and Glasses

After a brief introduction to the dynamics of supercooled liquids, we discuss some of the advantages and drawbacks of computer simulations of such systems. Subsequently we present the results of computer simulations in which the dynamics of a fragile glass former, a binary Lennard-Jones system, is compared to the one of a strong glass former, SiO_2. This comparison gives evidence that the reason for the different temperature dependence of these two types of glass formers lies in the transport mechanism for the particles in the vicinity of T_c, the critical temperature of mode-coupling theory. Whereas the one of the fragile glass former is described very well by the ideal version of mode-coupling theory, the one for the strong glass former is dominated by activated processes. In the last part of the article we review some simulations of glass formers in which the dynamics below the glass transition temperature was investigated. We show that such simulations might help to establish a connection between systems with self generated disorder (e.g. structural glasses) and quenched disorder (e.g. spin glasses).Comment: 37 pages of Latex, 11 figures, to appear as a Topical Review article in J. Phys.: Condens. Matte

Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages

A small scale sample nuclear waste package, consisting of a 28 mm diameter uranium penny encased in grout, was imaged by absorption contrast radiography using a single pulse exposure from an X-ray source driven by a high-power laser. The Vulcan laser was used to deliver a focused pulse of photons to a tantalum foil, in order to generate a bright burst of highly penetrating X-rays (with energy >500 keV), with a source size of <0.5 mm. BAS-TR and BAS-SR image plates were used for image capture, alongside a newly developed Thalium doped Caesium Iodide scintillator-based detector coupled to CCD chips. The uranium penny was clearly resolved to sub-mm accuracy over a 30 cm2 scan area from a single shot acquisition. In addition, neutron generation was demonstrated in situ with the X-ray beam, with a single shot, thus demonstrating the potential for multi-modal criticality testing of waste materials. This feasibility study successfully demonstrated non-destructive radiography of encapsulated, high density, nuclear material. With recent developments of high-power laser systems, to 10 Hz operation, a laser-driven multi-modal beamline for waste monitoring applications is envisioned

Dynamics of mitochondrial heteroplasmy in three families investigated via a repeatable re-sequencing study

Background: Originally believed to be a rare phenomenon, heteroplasmy - the presence of more than one mitochondrial DNA (mtDNA) variant within a cell, tissue, or individual - is emerging as an important component of eukaryotic genetic diversity. Heteroplasmies can be used as genetic markers in applications ranging from forensics to cancer diagnostics. Yet the frequency of heteroplasmic alleles may vary from generation to generation due to the bottleneck occurring during oogenesis. Therefore, to understand the alterations in allele frequencies at heteroplasmic sites, it is of critical importance to investigate the dynamics of maternal mtDNA transmission. Results: Here we sequenced, at high coverage, mtDNA from blood and buccal tissues of nine individuals from three families with a total of six maternal transmission events. Using simulations and re-sequencing of clonal DNA, we devised a set of criteria for detecting polymorphic sites in heterogeneous genetic samples that is resistant to the noise originating from massively parallel sequencing technologies. Application of these criteria to nine human mtDNA samples revealed four heteroplasmic sites. Conclusions: Our results suggest that the incidence of heteroplasmy may be lower than estimated in some other recent re-sequencing studies, and that mtDNA allelic frequencies differ significantly both between tissues of the same individual and between a mother and her offspring. We designed our study in such a way that the complete analysis described here can be repeated by anyone either at our site or directly on the Amazon Cloud. Our computational pipeline can be easily modified to accommodate other applications, such as viral re-sequencing

Bose-Einstein Correlations of Three Charged Pions in Hadronic Z^0 Decays

Bose-Einstein Correlations (BEC) of three identical charged pions were studied in 4 x 10^6 hadronic Z^0 decays recorded with the OPAL detector at LEP. The genuine three-pion correlations, corrected for the Coulomb effect, were separated from the known two-pion correlations by a new subtraction procedure. A significant genuine three-pion BEC enhancement near threshold was observed having an emitter source radius of r_3 = 0.580 +/- 0.004 (stat.) +/- 0.029 (syst.) fm and a strength of \lambda_3 = 0.504 +/- 0.010 (stat.) +/- 0.041 (syst.). The Coulomb correction was found to increase the \lambda_3 value by \~9% and to reduce r_3 by ~6%. The measured \lambda_3 corresponds to a value of 0.707 +/- 0.014 (stat.) +/- 0.078 (syst.) when one takes into account the three-pion sample purity. A relation between the two-pion and the three-pion source parameters is discussed.Comment: 19 pages, LaTeX, 5 eps figures included, accepted by Eur. Phys. J.