Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Statistics for Spatial Data.

THE author of this book ranks as the foremost American worker on insect morphology. His contributions on the subject are notable for their clarity and originality of thought, and the appearance of a volume, embodying his ideas in comprehensive form, is sure of a hearty welcome. In its preparation, Mr. Snodgrass has incorporated the results of much first-hand study with those of many recent investigators in the same field. He has produced an outstanding book wherein knowledge of facts is combined with that of function and, at the same time, theoretical conceptions of the origins and relationships of organs and parts are not overlooked. Principles of Insect Morphology
 By R. E. Snodgrass. (McGraw-Hill Publications in the Zoological Sciences.) Pp. ix + 667. (New York and London: McGraw-Hill Book Co., Inc., 1935.) 36s. net.

Principles of Insect Morphology

We have induced large elastic strains in ropes of single-wall carbon nanotubes, using an atomic force microscope in lateral force mode. Freely suspended ropes were observed to deform as elastic strings with tension proportional to elongation. Ropes were elastically deformed over >10 cycles without showing signs of plastic deformation. The maximum strain observed, 5.8±0.9%, gives a lower bound of 45±7 GPa for the tensile strength (specifically, yield stress) of single-wall nanotube ropes.

Elastic strain of freely suspended single-wall carbon nanotube ropes

The main objective of this research article is to analyze the impact of the production of some major crops, namely rice, jute, wheat, sugarcane, and potato on the agriculture sector in Bangladesh. The agriculture sector is considered an important sector of the Bangladeshi economy, which supplies a significant proportion of the gross domestic product (GDP). Annual time-series data for the period 1988–2017 is used for the study. Several econometric techniques are employed to examine the data, including the augmented Dickey-Fuller (ADF) test, Johansen cointegration test, and ordinary least squares (OLS) method. To validate the model, some residual diagnostic tests, namely a normality test, heteroskedasticity test, serial correlation test, and stability diagnostic test are conducted. The findings of the study demonstrate that there are two cointegrating equations in the model. Furthermore, both wheat and jute production have a significant positive impact on the agriculture sector. Although the impacts of rice and potato production on the agriculture sector are positive, these are not significant at the 5 or 10 percent significance level. On the other hand, sugarcane production has a negative and significant impact on the agriculture sector, which was not expected. Based on the results, this paper recommends that the government of Bangladesh should focus on designing and implementing new funding policies and subsidies to improve the growth, production, and development of the sugarcane sector. Finally, the government should be concerned about climate change-related factors that negatively affect crop production in Bangladesh.

/pdf/impacts-of-major-crop-production-on-the-agricultural-sector-1b1etfc4.pdf

Impacts of Major Crop Production on the Agricultural Sector in Bangladesh: A Time Series Analysis

The epidermis and dermis of albino mice born to females receiving oral sublethal doses of lead during pregnancy developed several abnormalities. These included perforations, tissue damage, cell deformity, and disordered organization of collagen bundles, as revealed by scanning electron microscopy. An increase in the concentrations of zinc, iron, magnesium, calcium and a decrease in that of copper was evident from atomic absorption spectroscopical analysis, when entire skin tissues were examined. Infrared spectroscopy revealed the occurrence of split bands in the spectra at 1,200-1,000 cm(-1), suggesting a reduction in the symmetry of the sulphate group (glycosaminoglycans) of skin probably caused by covalent bonding of it with lead.

Effect of prenatal lead toxicity on surface ultrastructural features, elemental composition and infrared absorption characteristics of the skin of albino mice.

The delamination is one of the major modes of failure occurring in the laminated composite due to insufficient bonding between the layers. In this paper, the natural frequencies of delaminated S-glass and E-glass epoxy cantilever composite plates are presented by employing the finite element method (FEM) approach. The rotary inertia and transverse shear deformation are considered in the present study. The effect of parameters such as the location of delamination along the length, across the thickness, the percentage of delamination, and ply-orientation angle on first three natural frequencies of the cantilever plates are presented for S-glass and E-glass epoxy composites. The standard eigenvalue problem is solved to obtain the natural frequencies and corresponding mode shapes. First three mode shape of S-Glass and E-Glass epoxy laminated composites are portrayed corresponding to different ply angle of lamina.

Sudip Dey

Papers

Impacts of Major Crop Production on the Agricultural Sector in Bangladesh: A Time Series Analysis

Effect of prenatal lead toxicity on surface ultrastructural features, elemental composition and infrared absorption characteristics of the skin of albino mice.

Effect of Delamination on Natural Frequencies of E-glass and S-glass Epoxy Composite Plates

Scanning electron microscopic studies on lenticular aberrations due to prolonged starvation in a cat fish (Heteropneustes fossilis, Bloch).

Prediction of WEDM Performances Using Clustering Techniques in ANFIS During Machining of A286 Superalloy