Refining the Reading Habits of Junior High School Pupils

The most pleasant part of this study is the opportunity which it afforded to work out a practical school-room problem unhampered by interference or indifference

Baryon Density and the Dilated Chiral Quark Model

We calculate perturbatively the effect of density on hadronic properties using the chiral quark model implemented by the QCD trace anomaly to see the possibility of constructing Lorentz invariant Lagrangian at finite density. We calculate the density dependent masses of the constituent quark, the scalar field and the pion in one-loop order using the technique of thermo field dynamics. In the chiral limit, the pion remains massless at finite density. It is found that the tadpole type corrections lead to the decreasing masses with increasing baryon density, while the radiative corrections induce Lorentz-symmetry-breaking terms. We found in the large $N_c$ limit with large scalar mass that the tadpoles dominate and the mean-field approximation is reliable, giving rise a Lorentz-invariant Lagrangian with masses decreasing as the baryon density increases.Comment: Late

Renormalization Group Analysis of \rho-Meson Properties at Finite Density

We calculate the density dependence of the $\rho$-meson mass and coupling constant($g_{\rho NN}$) for $\rho$-nucleon-nucleon vertex at one loop using the lagrangian where the $\rho$-meson is included as a dynamical gauge boson of a hidden local symmetry. From the condition that thermodynamic potential should not depend on the arbitrary energy scale, renormalization scale, one can construct a renormalization group equation for the thermodynamic potential and argue that the various renormalization group coefficients are functions of the density or temperature. We calculate the $\beta$-function for $\rho$-nucleon-nucleon coupling constant ($g_{\rho NN}$) and $\gamma$-function for $\rho$-meson mass ($\gamma_{m_\rho}$). We found that the $\rho$-meson mass and the coupling constant for $g_{\rho NN}$ drop as density increases in the low energy limit.Comment: 24 pages, 10 figures, revised versio

Diagnostic accuracy of single baseline measurement of Elecsys Troponin T high-sensitive assay for diagnosis of acute myocardial infarction in emergency department: systematic review and meta-analysis

Published onlineJournal ArticleMeta-AnalysisResearch Support, Non-U.S. Gov'tReviewOBJECTIVE: To obtain summary estimates of the accuracy of a single baseline measurement of the Elecsys Troponin T high-sensitive assay (Roche Diagnostics) for the diagnosis of acute myocardial infarction in patients presenting to the emergency department. DESIGN: Systematic review and meta-analysis of diagnostic test accuracy studies. DATA SOURCES: Medline, Embase, and other relevant electronic databases were searched for papers published between January 2006 and December 2013. STUDY SELECTION: Studies were included if they evaluated the diagnostic accuracy of a single baseline measurement of Elecsys Troponin T high-sensitive assay for the diagnosis of acute myocardial infarction in patients presenting to the emergency department with suspected acute coronary syndrome. STUDY APPRAISAL AND DATA SYNTHESIS: The first author screened all titles and abstracts identified through the searches and selected all potentially relevant papers. The screening of the full texts, the data extraction, and the methodological quality assessment, using the adapted QUADAS-2 tool, were conducted independently by two reviewers with disagreements being resolved through discussion or arbitration. If appropriate, meta-analysis was conducted using the hierarchical bivariate model. RESULTS: Twenty three studies reported the performance of the evaluated assay at presentation. The results for 14 ng/L and 3-5 ng/L cut-off values were pooled separately. At 14 ng/L (20 papers), the summary sensitivity was 89.5% (95% confidence interval 86.3% to 92.1%) and the summary specificity was 77.1% (68.7% to 83.7%). At 3-5 ng/L (six papers), the summary sensitivity was 97.4% (94.9% to 98.7%) and the summary specificity was 42.4% (31.2% to 54.5%). This means that if 21 of 100 consecutive patients have the target condition (21%, the median prevalence across the studies), 2 (95% confidence interval 2 to 3) of 21 patients with acute myocardial infarction will be missed (false negatives) if 14 ng/L is used as a cut-off value and 18 (13 to 25) of 79 patients without acute myocardial infarction will test positive (false positives). If the 3-5 ng/L cut-off value is used, <1 (0 to 1) patient with acute myocardial infarction will be missed and 46 (36 to 54) patients without acute myocardial infarction will test positive. CONCLUSIONS: The results indicate that a single baseline measurement of the Elecsys Troponin T high-sensitive assay could be used to rule out acute myocardial infarction if lower cut-off values such as 3 ng/L or 5 ng/L are used. However, this method should be part of a comprehensive triage strategy and may not be appropriate for patients who present less than three hours after symptom onset. Care must also be exercised because of the higher imprecision of the evaluated assay and the greater effect of lot-to-lot reagent variation at low troponin concentrations. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration number CRD42013003926.This research was funded by the South West Academic Health Science Network (AHSN) and the National Institute for Health Research (NIHR) Collaboration for Leadership for Applied Health Research and Care for the South West Peninsula

Stochastic simulation for budget prediction for large surface mines in the South African mining industry

This article investigates the complex problem of a budgeting process for a large mining operation. Strict adherence to budget infers that financial results align with goals. In reality, the budget is not a predetermined entity but emerges as the sum of the enterprise’s operational plans. These are highly interdependent, being influenced by unforeseeable events and operational decision-making. Limitations of stochastic simulations, normally applied in the project environment but not in budgeting, are examined and a model enabling their application is proposed. A better understanding of budget failure in large mines emerges, showing that the budget should be viewed as a probability distribution rather than a single deterministic value. The strength of the model application lies with the combining of stochastic simulation, probability theory, financial budgeting, and practical scheduling to predict budget achievement, reflected as a probability distribution. The principal finding is the interpretation of the risk associated with, and constraints pertaining to, the budget. The model utilizes a four-dimensional (space and time) schedule, linking key drivers through activity-based costing to the budget. It offers a highly expressive account of deduction regarding fund application for budget achievement, emphasizing that ’it is better to be approximately right than precisely wrong’.http://www.saimm.co.za/journal-papersam201

Lorentz gauge theory as a model of emergent gravity

We consider a class of Lorentz gauge gravity theories within Riemann-Cartan geometry which admits a topological phase in the gravitational sector. The dynamic content of such theories is determined only by the contortion part of the Lorentz gauge connection. We demonstrate that there is a unique Lagrangian that admits propagating spin one mode in correspondence with gauge theories of other fundamental interactions. Remarkably, despite the R^2 type of the Lagrangian and non-compact structure of the Lorentz gauge group, the model possesses rather a positive-definite Hamiltonian. This has been proved in the lowest order of perturbation theory. This implies further consistent quantization and leads to renormalizable quantum theory. It is assumed that the proposed model describes possible mechanism of emergent Einstein gravity at very early stages of the Universe due to quantum dynamics of contortion.Comment: 11 pages, final version, minor correction

Four-nucleon contact interactions from holographic QCD

We calculate the low energy constants of four-nucleon interactions in an effective chiral Lagrangian in holographic QCD. We start with a D4-D8 model to obtain meson-nucleon interactions and then integrate out massive mesons to obtain the four-nucleon interactions in 4D. We end up with two low energy constants at the leading order and seven of them at the next leading order, which is consistent with the effective chiral Lagrangian. The values of the low energy constants are evaluated with the first five Kaluza-Klein resonances.Comment: 28 page

Finite-Temperature Corrections in the Dilated Chiral Quark Model

We calculate the finite-temperature corrections in the dilated chiral quark model using the effective potential formalism. Assuming that the dilaton limit is applicable at some short length scale, we interpret the results to represent the behavior of hadrons in dense {\it and} hot matter. We obtain the scaling law, $\frac{f_{\pi}(T)}{f_{\pi}} = \frac{m_Q (T)}{m_Q} \simeq \frac{m_{\sigma}(T)}{m_{\sigma}}$ while we argue, using PCAC, that pion mass does not scale within the temperature range involved in our Lagrangian. It is found that the hadron masses and the pion decay constant drop faster with temperature in the dilated chiral quark model than in the conventional linear sigma model that does not take into account the QCD scale anomaly. We attribute the difference in scaling in heat bath to the effect of baryonic medium on thermal properties of the hadrons. Our finding would imply that the AGS experiments (dense {\it and} hot matter) and the RHIC experiments (hot and dilute matter) will ``see" different hadron properties in the hadronization phase.Comment: 13 pages , LaTe

Symmetry energy of dense matter in holographic QCD

We study the nuclear symmetry energy of dense matter using holographic QCD. To this end, we consider two flavor branes with equal quark masses in a D4/D6/D6 model. We find that at all densities the symmetry energy monotonically increases. At small densities, it exhibits a power law behavior with the density, $E_{\rm sym} \sim \rho^{1/2}$.Comment: 9 pages, 3 figure

Micro-Auger Electron Spectroscopy Studies of Chemical and Electronic Effects at GaN-Sapphire Interfaces

We have used cross-sectional micro-Auger electron spectroscopy (AES), coupled with micro-cathodoluminescence (CLS) spectroscopy, in a UHV scanning electron microscope to probe the chemical and related electronic features of hydride vapor phase epitaxy GaN/sapphire interfaces on a nanometer scale. AES images reveal dramatic evidence for micron-scale diffusion of O from Al2O3 into GaN. Conversely, plateau concentrations of N can extend microns into the sapphire, corresponding spatially to a 3.8 eV defect emission and Auger chemical shifts attributed to Al-N-O complexes. Interface Al Auger signals extending into GaN indicates AlGaN alloy formation, consistent with a blue-shifted CLS local interface emission. The widths of such interface transition regions range from ≪100 nm to ∼1 μm, depending on surface pretreatment and growth conditions. Secondary ion mass spectroscopy depth profiles confirm the elemental character and spatial extent of diffusion revealed by micro-AES, showing that cross-sectional AES is a useful approach to probe interdiffusion and electronic properties at buried interfaces