On the Efficient Calculation of a Linear Combination of Chi-Square Random Variables with an Application in Counting String Vacua

Linear combinations of chi square random variables occur in a wide range of fields. Unfortunately, a closed, analytic expression for the pdf is not yet known. As a first result of this work, an explicit analytic expression for the density of the sum of two gamma random variables is derived. Then a computationally efficient algorithm to numerically calculate the linear combination of chi square random variables is developed. An explicit expression for the error bound is obtained. The proposed technique is shown to be computationally efficient, i.e. only polynomial in growth in the number of terms compared to the exponential growth of most other methods. It provides a vast improvement in accuracy and shows only logarithmic growth in the required precision. In addition, it is applicable to a much greater number of terms and currently the only way of computing the distribution for hundreds of terms. As an application, the exponential dependence of the eigenvalue fluctuation probability of a random matrix model for 4d supergravity with N scalar fields is found to be of the asymptotic form exp(-0.35N).Comment: 21 pages, 19 figures. 3rd versio

A simple, rapid and efficient method for the extraction of genomic DNA from Allium roseum L. (Alliaceae)

The isolation of intact, high-molecular-mass genomic DNA is essential for many molecular biology applications including long range PCR, endonuclease restriction digestion, southern blot analysis, and genomic library construction. Many protocols are available for the extraction of DNA from plant material, but obtain it is difficult in many plants because of metabolites that interfere with DNA isolation procedures and subsequent applications. With frame of the present work, we developed the first reliable and efficient method for isolatingAllium roseum L. genomic DNA that is free from polysaccharides and polyphenols. This protocol uses 100 mM Tris-HCl (pH 8), 20 mM EDTA, 1.4 M NaCl, 3% PVP (polyvinylpyrrolidone 40.000), 3% mercaptoethanol, and an incubation at 65°C for 1 h. The purity of isolated genomic DNA was confirmed by spectrophotometric analyses (A260/230 ratio of 1.947, A260/280 of 1.804). DNA was obtained in the amount of 189  Allium roseum L. genomic DNA that is free from polysaccharides and polyphenols. This protocol uses 100 mM Tris-HCl (pH 8), 20 mM EDTA, 1.4 M NaCl, 3% PVP (polyvinylpyrrolidone 40.000), 3% mercaptoethanol, and an incubation at 65°C for 1 h. The purity of isolated genomic DNA was confirmed by spectrophotometric analyses (A260/230 ratio of 1.947, A260/280 of 1.804). DNA was obtained in the amount of 189 Allium roseum L. genomic DNA that is free from polysaccharides and polyphenols. This protocol uses 100 mM Tris-HCl (pH 8), 20 mM EDTA, 1.4 M NaCl, 3% PVP (polyvinylpyrrolidone 40.000), 3% mercaptoethanol, and an incubation at 65°C for 1 h. The purity of isolated genomic DNA was confirmed by spectrophotometric analyses (A260/230 ratio of 1.947, A260/280 of 1.804). DNA was obtained in the amount of 189 g per gram of leaf material, and it proved amenable to restriction digestion

A review on cloud computing adoption: an exploratory analysis

The world has been witnessed with many technological revolutions. One of them is the computing technologies. There have been many revolutions such as mainframe computers, super computers, web technologies, Internet, grid computing, utility computing, etc. Cloud computing is another evolutions in the field of computing and it has been evolved from the earlier computing technologies by the integration of some of them and removing the obstacles encountered in them as a new technology. Amazon, Google, Microsoft, Salesforce.com, are some of the organizations who provide this technology to organizations and personal users. Cloud computing has attracted many people, researchers, and professionals towards it Many people have done researches on it and many articles and conference papers on varying aspects of cloud computing has been published. The purpose of this is paper is to review those research articles and conference papers to compile the concepts and various aspects of it in order to enlighten the concept more understandable to all varieties of people since it has been a new concept and many people are not aware of it by using exploratory analysis as methodology. The paper focuses on the different definitions of cloud computing, characteristics, underlying technologies, different cloud services, cloud deployment model, advantages and disadvantages of cloud computing, cloud computing implementation issues, adoption status of cloud computing, and future research areas

Effects of Ethrel Application and Packaging on Mango Fruit Quality

    Experiments were conducted at the National Institute for the Promotion  of Horticultural Exports, University of Gezira, Wad  Medani, Sudan, during May 1997 and 1998 to investigate the effects of Ethrel and polyethylene packaging on mango fruit quality. Mango fruit quality, Mango fruits were  harvested at the mature-green stage and treated with Ethrel or  left as control. Fruits were packed in either intact or perforated polyetlhylene packages or left unpacked. The experiments were set up in a completely randomized design with three replications. Ethrel treatment accelerated  the rate of fruit ripening as shown by an increase in total soluble solids, yellowing and a decrease in fruit firmness and starch content Fruits packed in intact polyethylene packages resulted in the  lowest weight loss, followed by those packed in perforated films, whereas unpacked fruits showed the highest weight loss and lowest quality manifested in shriveling and deterioratio

Finite Element Analysis of the Ramberg-Osgood Bar

In this work, we present a priori error estimates of finite element approximations of the solution for the equilibrium equation of an axially loaded Ramberg-Osgood bar. The existence and uniqueness of the solution to the associated nonlinear two point boundary value problem is established and used as a foundation for the finite element analysis