The Application Queueing Theory in Singkil Service Car Wash

In the service industry, long queuing will for waiting to be served is a taboo. Since, customers will switch to other competitors and reduce revenues. This research is conducted to find out the effectiveness and efficiency in queuing system in order to achieve customer satisfaction in the Singkil Service Car Wash. This research used model B M/M/S formula to get the average incoming customer. In normal condition, there were 2 customers and 3 line services, in the quiet condition, 1 customer and 2 line services, in the crowded condition there were 3 customers and 4 line services. The Singkil Service Car Wash performance is under optimal condition since the number of customers who came is still low. It is advisable to the owner of the Singkil Service Car Wash to reduce the service line and to reassign the unproductive employees to other area so the worker productivity can be retained. This will result in a more efficient and effective employee's management and better profit for the company

Using the 'myVolcano' mobile phone app for citizen science in St. Vincent and the Grenadines : a pilot study

The British Geological Survey (BGS) has been working with Caribbean partners on the role of citizen science in increasing resilience to natural hazards. The work has largely focused on the potential use of the myVolcano smartphone app, which was developed by the BGS following the 2010 Eyafjallajökull and 2011 Grímsvötn eruptions in Iceland. During these eruptions the BGS asked the UK public to collect particle samples, subsequently analysing these for ash presence to map the distribution of ash fallout across the UK. These requests led to the development of the myVolcano app, which was designed to capture transboundary and distal observations of volcanic ash and emissions. The observations are made visible to other users via an interactive map built into the app. The map interface has global coverage and the data collection methods (free-text descriptions and photographs) are such that information about any natural hazard, anywhere in the world, can be captured. In 2015, BGS carried out an ESRC-DfID-NERC funded scoping study in collaboration with the University of the West Indies’ Seismic Research Centre (UWI SRC), to test the potential use of the app in environments affected by proximal volcanic hazards. The study focused on St. Vincent and the Grenadines and investigated the potential for capturing a wider variety of observations for use by the public, operational scientists and civil protection. The study, which included a combination of desk study and remote interviews, highlighted the potential for, and challenges of, using such an app for increasing resilience to natural hazards and the need for a follow-up study in St Vincent. In March 2017, a workshop and school activities were held in St. Vincent to collect feedback from potential users of myVolcano, hereafter referred to as the pilot study. Workshop participants came from across government, monitoring agencies, emergency response and telecommunications. As part of the workshop, a multi-hazard scenario was ‘played out’ to stimulate discussions on the usability of the app, data gathering and processing, and participants’ use of existing citizen science applications. Discussions developed around data validation and quality assurance, data sharing and presentation, local management of data by nominated scientists (e.g. to facilitate real-time decision making) and the associated need for a locally appropriate app (i.e. no one size fits all). This last point is particularly significant when considering the utility of an app in several countries – the user interface, at least, requires specific tailoring to the country’s needs. Using this feedback, the BGS Official Development Assistance (ODA) programme is currently funding collaborations with Caribbean partners in order to modify the app to meet the local requirements, including widening the multi-hazard application and enhancing two-way information sharing. Of particular importance is how best to share critical information with those making observations and how to make observations available to decision-makers and monitoring scientists in real-time (e.g. through local management of the app)

Modular Invariance of Finite Size Corrections and a Vortex Critical Phase

We analyze a continuous spin Gaussian model on a toroidal triangular lattice with periods $L_0$ and $L_1$ where the spins carry a representation of the fundamental group of the torus labeled by phases $u_0$ and $u_1$. We find the {\it exact finite size and lattice corrections}, to the partition function $Z$, for arbitrary mass $m$ and phases $u_i$. Summing $Z^{-1/2}$ over phases gives the corresponding result for the Ising model. The limits $m\rightarrow0$ and $u_i\rightarrow0$ do not commute. With $m=0$ the model exhibits a {\it vortex critical phase} when at least one of the $u_i$ is non-zero. In the continuum or scaling limit, for arbitrary $m$, the finite size corrections to $-\ln Z$ are {\it modular invariant} and for the critical phase are given by elliptic theta functions. In the cylinder limit $L_1\rightarrow\infty$ the ``cylinder charge'' $c(u_0,m^2L_0^2)$ is a non-monotonic function of $m$ that ranges from $2(1+6u_0(u_0-1))$ for $m=0$ to zero for $m\rightarrow\infty$.Comment: 12 pages of Plain TeX with two postscript figure insertions called torusfg1.ps and torusfg2.ps which can be obtained upon request from [email protected]

The Specific Heat of a Ferromagnetic Film.

We analyze the specific heat for the $O(N)$ vector model on a $d$-dimensional film geometry of thickness $L$ using ``environmentally friendly'' renormalization. We consider periodic, Dirichlet and antiperiodic boundary conditions, deriving expressions for the specific heat and an effective specific heat exponent, \alpha\ef. In the case of $d=3$, for $N=1$, by matching to the exact exponent of the two dimensional Ising model we capture the crossover for \xi_L\ra\infty between power law behaviour in the limit {L\over\xi_L}\ra\infty and logarithmic behaviour in the limit {L\over\xi_L}\ra0 for fixed $L$, where $\xi_L$ is the correlation length in the transverse dimensions.Comment: 21 pages of Plain TeX. Postscript figures available upon request from [email protected]

Algorithm for normal random numbers

We propose a simple algorithm for generating normally distributed pseudo random numbers. The algorithm simulates N molecules that exchange energy among themselves following a simple stochastic rule. We prove that the system is ergodic, and that a Maxwell like distribution that may be used as a source of normally distributed random deviates follows when N tends to infinity. The algorithm passes various performance tests, including Monte Carlo simulation of a finite 2D Ising model using Wolff's algorithm. It only requires four simple lines of computer code, and is approximately ten times faster than the Box-Muller algorithm.Comment: 5 pages, 3 encapsulated Postscript Figures. Submitted to Phys.Rev.Letters. For related work, see http://pipe.unizar.es/~jf

A new test for random number generators: Schwinger-Dyson equations for the Ising model

We use a set of Schwinger-Dyson equations for the Ising Model to check several random number generators. For the model in two and three dimensions, it is shown that the equations are sensitive tests of bias originated by the random numbers. The method is almost costless in computer time when added to any simulation.Comment: 6 pages, 3 figure

The relations between DISC-IV DSM diagnoses of ADHD and multi-informant CBCL-AP syndrome scores

Background: Previous studies have examined the relation between attention problems (APs) obtained with the Child Behavior Checklist (CBCL) and attention deficit hyperactivity disorder (ADHD) assessed with the Diagnostic and Statistical Manual of Mental Disorders (DSM). We will examine this relation across sex using multi-informant data. Methods: Parents of 12 538 twins, aged 7, 10, and 12 years, and teachers of twins, aged 10 years, completed the questionnaires. The mothers of a sample of 283 boys and 291 girls who scored either low or high on longitudinal maternal CBCL-AP were interviewed. Results: Children with a low AP score obtained a negative ADHD diagnosis in 96% of cases. Children with a high AP score obtained a positive diagnosis in 36% (girls) and 59% (boys) of cases. The association between paternal and maternal AP ratings and ADHD was the same, whereas the association between teacher AP ratings and ADHD was low. Conclusions: The association between AP and ADHD is higher in boys than girls, possibly because of a bias toward the male manifestation of ADHD. © 2006 Elsevier Inc. All rights reserved

Vitamin D Status and its Association with Morbidity including Wasting and Opportunistic Illnesses in HIV-Infected Women in Tanzania.

Vitamin D has a potential role in preventing HIV-related complications, based on its extensive involvement in immune and metabolic function, including preventing osteoporosis and premature cardiovascular disease. However, this association has not been examined in large studies or in resource-limited settings. Vitamin D levels were assessed in 884 HIV-infected pregnant women at enrollment in a trial of multivitamin supplementation (excluding vitamin D) in Tanzania. Information on HIV related complications was recorded during follow-up (median, 70 months). Proportional hazards models and generalized estimating equations were used to assess the relationship of vitamin D status with these outcomes. Women with low vitamin D status (serum 25-hydroxyvitamin D<32 ng/mL) had 43% higher risk of reaching a body mass index (BMI) less than 18 kg/m(2) during the first 2 years of follow-up, compared to women with adequate vitamin D levels (hazard ratio [HR]: 1.43; 95% confidence intervals: [1.03-1.99]). The relationship between continuous vitamin D levels and risk of BMI less than 18 kg/m(2) during follow-up was inverse and linear (p=0.03). Women with low vitamin D levels had significantly higher incidence of acute upper respiratory infections (HR: 1.27 [1.04-1.54]) and thrush (HR: 2.74 [1.29-5.83]) diagnosed during the first 2 years of follow-up. Low vitamin D status was a significant risk factor for wasting and HIV-related complications such as thrush during follow-up in this prospective cohort in Tanzania. If these protective associations are confirmed in randomized trials, vitamin D supplementation could represent a simple and inexpensive method to improve health and quality of life of HIV-infected patients, particularly in resource-limited settings

Kronecker's Double Series and Exact Asymptotic Expansion for Free Models of Statistical Mechanics on Torus

For the free models of statistical mechanics on torus, exact asymptotic expansions of the free energy, the internal energy and the specific heat in the vicinity of the critical point are found. It is shown that there is direct relation between the terms of the expansion and the Kronecker's double series. The latter can be expressed in terms of the elliptic theta-functions in all orders of the asymptotic expansion.Comment: REVTeX, 22 pages, this is expanded version which includes exact asymptotic expansions of the free energy, the internal energy and the specific hea

Exact Finite-Size-Scaling Corrections to the Critical Two-Dimensional Ising Model on a Torus

We analyze the finite-size corrections to the energy and specific heat of the critical two-dimensional spin-1/2 Ising model on a torus. We extend the analysis of Ferdinand and Fisher to compute the correction of order L^{-3} to the energy and the corrections of order L^{-2} and L^{-3} to the specific heat. We also obtain general results on the form of the finite-size corrections to these quantities: only integer powers of L^{-1} occur, unmodified by logarithms (except of course for the leading $\log L$ term in the specific heat); and the energy expansion contains only odd powers of L^{-1}. In the specific-heat expansion any power of L^{-1} can appear, but the coefficients of the odd powers are proportional to the corresponding coefficients of the energy expansion.Comment: 26 pages (LaTeX). Self-unpacking file containing the tex file and three macros (indent.sty, eqsection.sty, subeqnarray.sty). Added discussions on the results and new references. Version to be published in J. Phys.