Limitation of the Press-Schechter Formalism

The Press-Schechter(PS) formalism for the mass function of the collapsed objects are reanalyzed. The factor of two in the Press-Schechter formalism is argued to be correct in the sharp $k$-space filter even when we use the another approach proposed by Jedamzik(1994) in the cloud-in-cloud problem, which is different from the previous approach by Peacock & Heavens(1990) and Bond et al.(1991). The spatial correlation of the density fluctuations, however, had been neglected in the cloud-in-cloud problem. The effects of this spatial correlation is analyzed by using the Jedamzik formalism and it is found that this effect alter the PS mass function especially on larger mass scales. Furthermore the exact formula of deriving mass function is shown. We also find that the probability of the overlap of the collapsed objects can be neglected on very small mass scales while it might not be neglected on other mass scales.Comment: 23 pages, uuencoded compressed Postscrip

Why my disease is important: metrics of disease occurrence used in the introductory sections of papers in three leading general medical journals in 1993 and 2003.

BACKGROUND: We assessed the metrics used in claims about disease importance made in the introductory sections of scientific papers published in 1993 and 2003. We were interested in the choice of metric in circumstances where establishing the relative social importance of a disease was, presumptively, a primary objective. METHODS: This study consisted of a textual examination of the introductory statements from papers retrieved from MEDLINE. Papers were published in the New England Journal of Medicine, The Lancet, and the Journal of the American Medical Association during the first halves of 1993 and 2003, and were selected on the basis of keywords found in a pilot study to be associated with claims about disease importance. RESULTS: We found 143 papers in 1993 and 264 papers in 2003 included claims about disease importance in their introductory sections, and characteristics of these claims were abstracted. Of the quotes identified in the papers and articles examined, most used counts, prevalence, or incidence measurements. Some also used risk estimates and economic quantities to convey the importance of the disease. There was no change in the types of metrics used between 1993 and 2003. Very few articles, even in 2003, used metrics that weighted disease onsets by the expected consequent loss of healthy time -- such as years of life lost, quality-adjusted life years, and/or disability-adjusted life years. CONCLUSIONS: Claims about the relative importance of diseases continued to be overwhelmingly expressed in terms of counts (of deaths and disease onsets) and comparisons of counts, rates, and risks. Where the aim is to convey the burden that a given disease imposes on a society, "event-based" metrics might be less fit for the purpose than "time-based" metrics. More attention is needed to how the choice of metric should relate to the purpose at hand.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Numerical and experimental investigations on vibration of delaminated composite shell

The laminated composite shell structures are acting as most desired structure in various field of modern engineering. These are frequently used in various industries such as aerospace, construction, nuclear field, automotive, petrochemical industries, ship & rocket building due to high specific strength and stiffness of composite materials. Because of their ability to meet the design requirements of strength & stiffness, composite materials have greater importance in recent years. But during the manufacturing and service life, there will be delamination damage in composite laminate which is not visible due to embedded within the composite structures. However it reduces the strength and stiffness of the laminated structures and also effects on the vibration characteristics of the structures. The present work deals with the numerical and experimental investigation on free vibration characteristics of delaminated composite cylindrical shell. Experimental setup and procedure of the modal testing were described. Fabrication procedure of the shell was also described. Natural frequencies were determined using a computer programme in MATLAB environment based on finite element method (FEM). The results using the present formulation were compared with other existing literature. Also comparison was made between the experimental values and numerical predictions using FEM. The effects of percentage delamination on natural frequency of the composite shell were studied. The influence of various parameters i.e. curvature, delamination area, ply lay-up and aspect ratio on vibration response were discussed for different boundary conditions

Prediction ability of Altman model for bankruptcy in Greek enterprises

This study initially decodes and analyzes the financial robustness of companies that bankrupt in 2012, aiming to determine with the use of historical data the factors that could forecast the bankruptcy of these enterprises. The year 2012 was selected because Greece was the unique country from the GIIPS states (Greece, Ireland, Italy, Portugal and Spain) in which paradoxically 2012 is the year with inversion of the tendency and reduction (6.74%) in the number of recorded corporate bankruptcies. For the research purpose the second- revised Altman Z-score model is used, which was applied in a ten sample of bankrupted enterprises from various branches. The rate of success of the model in the final sample of enterprises one year before the bankruptcy is 100%, which means higher predictability than the percentage of 94% exported by Altman in 1968. As long as it concerns the rate of success 2 years before bankruptcy it was presented smaller compared to the -1 year (80%), however comparing the result with the application of Altman (72%), the model in the present research presented also higher prediction ability. The reversal of the trend of the legally recorded bankruptcies in Greece seems to be due to statistical rather than economic reasons. Many small and medium size firms as well as sole traders led to closure, but their bankruptcy was not recorded as judicial bankrup

Why choice of metric matters in public health analyses: a case study of the attribution of credit for the decline in coronary heart disease mortality in the US and other populations

RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.Abstract Background Reasons for the widespread declines in coronary heart disease (CHD) mortality in high income countries are controversial. Here we explore how the type of metric chosen for the analyses of these declines affects the answer obtained. Methods The analyses we reviewed were performed using IMPACT, a large Excel based model of the determinants of temporal change in mortality from CHD. Assessments of the decline in CHD mortality in the USA between 1980 and 2000 served as the central case study. Results Analyses based in the metric of number of deaths prevented attributed about half the decline to treatments (including preventive medications) and half to favourable shifts in risk factors. However, when mortality change was expressed in the metric of life-years-gained, the share attributed to risk factor change rose to 65%. This happened because risk factor changes were modelled as slowing disease progression, such that the hypothetical deaths averted resulted in longer average remaining lifetimes gained than the deaths averted by better treatments. This result was robust to a range of plausible assumptions on the relative effect sizes of changes in treatments and risk factors. Conclusions Time-based metrics (such as life years) are generally preferable because they direct attention to the changes in the natural history of disease that are produced by changes in key health determinants. The life-years attached to each death averted will also weight deaths in a way that better reflects social preferences.Peer Reviewe

Shapes and Positions of Black Hole Shadows in Accretion Disks and Spin Parameters of Black Holes

Can we determine a spin parameter of a black hole by observation of a black hole shadow in an accretion disk? In order to answer this question, we make a qualitative analysis and a quantitative analysis of a shape and a position of a black hole shadow casted by a rotating black hole on an optically thick accretion disk and its dependence on an angular momentum of a black hole. We have found black hole shadows with a quite similar size and a shape for largely different black hole spin parameters and a same black hole mass. Thus, it is practically difficult to determine a spin parameter of a black hole from a size and a shape of a black hole shadow in an accretion disk. We newly introduce a bisector axis of a black hole shadow named a shadow axis. For a rotating black hole a shape and a position of a black hole shadow are not symmetric with respect to a rotation axis of a black hole shadow. So, in this case the minimum interval between a mass center of a black hole and a shadow axis is finite. An extent of this minimum interval is roughly proportional to a spin parameter of a black hole for a fixed inclination angle between a rotation axis of a black hole and a direction of an observer. In order to measure a spin parameter of a black hole, if a shadow axis is determined observationally, it is crucially important to determine a position of a mass center of a black hole in a region of a black hole shadow.Comment: 13 pages, 6 figures, accepted for publication in Ap

Bacterial contamination of white coats and hands of healthcare workers at mansoura university children’s hospital, Mansoura-Egypt

Background: Transmission of hospital acquired infections (HAIs) may be associated with contamination of healthcare workers’ (HCWs) hands and white coats.Objective: The purpose of this study was to clarify the role of HCWs’ white coats in transmitting HAIs and to determine the association between bacterial contamination of HCWs’ hands and white coats.Methods: A total of 154 HCWs were enrolled in the study; different samples were taken from their hands and white coats. Samples were processed and both microbiological and biochemical characterization of the isolates were done using standard microbiological protocols.Results: Up to 65.6% of hands and 61% of coats of HCWs were contaminated by microorganisms. Staphylococcus aureus was the most commonly isolated organisms from both hands and coats of HCWs (29.2%, 27.3% respectively) followed by MRSA (22.1%, 24.7% respectively).Conclusions: The risk for contamination of hands and coats of HCWs is high in different clinical settings. In order to reduce the rate of HAIs, a strict dress protocol should be set into play to prevent cross contamination between HCWs and patients.Keywords: contamination, HCWs, coat, hand, Staphylococcus aureus, MRSA. Contamination bacterienne de manteaux blancs et de mains de soins de sante a l'hopital pour enfants de l'universite mansoura, Mansoura-EgypteContexte: La transmission des infectionsObjectif: Le but de cette étude était de déterminer l'étendue, le type et l'association entre la contamination bactérienne des mains des travailleurs de la santé et les blouses blanches.Méthodes: Au total, 154 travailleurs de la santé ont été inclus dans l'étude; différents échantillons ont été pris de leurs mains et des manteaux blancs. Les échantillons ont été traités et la caractérisation microbiologique et biochimique des isolats a été effectuée en utilisant des protocoles microbiologiques standard.Résultats: Jusqu'à 65,6% des mains et 61% des couches de TS ont été contaminées par des micro-organismes. Le Staphylococcus aureus était le plus souvent isolé des deux mains et des deux sexes (29,2%, 27,3%), suivi par le SARM (22,1%, 24,7% respectivement).Conclusions: Le risque de contamination des mains et des couches de TS est élevé dans différents contextes cliniques. Afin de réduire le taux d'IASS, un protocole vestimentaire strict devrait être mis en place pour prévenir la contamination croisée entre les travailleurs de la santé et les patients.Mots clés: contamination, agents de santé, manteau, main, Staphylococcus aureus, SAR