A Classification and Survey of Computer System Performance Evaluation Techniques

Classification and survey of computer system performance evaluation technique

Mean-Field Analysis of Coding Versus Replication in Large Data Storage Systems

We study cloud storage systems with a very large number of files stored in a very large number of servers. In such systems, files are either replicated or coded to ensure reliability, i.e., to guarantee file recovery from server failures. This redundancy in storage can further be exploited to improve system performance (mean file-access delay) through appropriate load-balancing (routing) schemes. However, it is unclear whether coding or replication is better from a system performance perspective since the corresponding queueing analysis of such systems is, in general, quite difficult except for the trivial case when the system load asymptotically tends to zero. Here, we study the more difficult case where the system load is not asymptotically zero. Using the fact that the system size is large, we obtain a mean-field limit for the steady-state distribution of the number of file access requests waiting at each server. We then use the mean-field limit to show that, for a given storage capacity per file, coding strictly outperforms replication at all traffic loads while improving reliability. Further, the factor by which the performance improves in the heavy traffic is at least as large as in the light-traffic case. Finally, we validate these results through extensive simulations

Theoretical Analysis of STM Experiments at Rutile TiO_2 Surfaces

A first-principles atomic orbital-based electronic structure method is used to investigate the low index surfaces of rutile Titanium Dioxide. The method is relatively cheap in computational terms, making it attractive for the study of oxide surfaces, many of which undergo large reconstructions, and may be governed by the presence of Oxygen vacancy defects. Calculated surface charge densities are presented for low-index surfaces of TiO$_2$, and the relation of these results to experimental STM images is discussed. Atomic resolution images at these surfaces tend to be produced at positive bias, probing states which largely consist of unoccupied Ti 3$d$ bands, with a small contribution from O 2$p$. These experiments are particularly interesting since the O atoms tend to sit up to 1 angstrom above the Ti atoms, so providing a play-off between electronic and geometric structure in image formation.Comment: 9 pages, Revtex, 3 postscript figures, accepted by Surf. Scienc

Volterra Accentuated Non-Linear Dynamical Admittance (VANYA) to model Deforestation: An Exemplification from the Amazon Rainforest

Intelligent automation supports us against cyclones, droughts, and seismic events with recent technology advancements. Algorithmic learning has advanced fields like neuroscience, genetics, and human-computer interaction. Time-series data boosts progress. Challenges persist in adopting these approaches in traditional fields. Neural networks face comprehension and bias issues. AI's expansion across scientific areas is due to adaptable descriptors and combinatorial argumentation. This article focuses on modeling Forest loss using the VANYA Model, incorporating Prey Predator Dynamics. VANYA predicts forest cover, demonstrated on Amazon Rainforest data against other forecasters like Long Short-Term Memory, N-BEATS, RCN

EBF1-deficient bone marrow stroma elicits persistent changes in HSC potential

Crosstalk between mesenchymal stromal cells (MSCs) and hematopoietic stem cells (HSCs) is essential for hematopoietic homeostasis and lineage output. Here, we investigate how transcriptional changes in bone marrow (BM) MSCs result in long-lasting effects on HSCs. Single-cell analysis of Cxcl12-abundant reticular (CAR) cells and PDGFRα+Sca1+ (PαS) cells revealed an extensive cellular heterogeneity but uniform expression of the transcription factor gene Ebf1. Conditional deletion of Ebf1 in these MSCs altered their cellular composition, chromatin structure and gene expression profiles, including the reduced expression of adhesion-related genes. Functionally, the stromal-specific Ebf1 inactivation results in impaired adhesion of HSCs, leading to reduced quiescence and diminished myeloid output. Most notably, HSCs residing in the Ebf1-deficient niche underwent changes in their cellular composition and chromatin structure that persist in serial transplantations. Thus, genetic alterations in the BM niche lead to long-term functional changes of HSCs

Integrin β1 regulates marginal zone B cell differentiation and PI3K signaling

Marginal zone (MZ) B cells represent innate-like B cells that mediate a fast immune response. The adhesion of MZ B cells to the marginal sinus of the spleen is governed by integrins. Here, we address the question of whether β1-integrin has additional functions by analyzing Itgb1fl/flCD21Cre mice in which the β1-integrin gene is deleted in mature B cells. We find that integrin β1–deficient mice have a defect in the differentiation of MZ B cells and plasma cells. We show that integrin β1–deficient transitional B cells, representing the precursors of MZ B cells, have enhanced B cell receptor (BCR) signaling, altered PI3K and Ras/ERK pathways, and an enhanced interaction of integrin-linked kinase (ILK) with the adaptor protein Grb2. Moreover, the MZ B cell defect of integrin β1–deficient mice could, at least in part, be restored by a pharmacological inhibition of the PI3K pathway. Thus, β1-integrin has an unexpected function in the differentiation and function of MZ B cells

Closed Form Solution for Parabolic Flow of a Inclined Isothermal Plate With Uniform Mass Diffusion

The fluid flow across an unbounded horizontal plate embedded with uniform mass diffusion is studied in this article together with the impacts of the chemical reaction and parabolic motion, while the temperature and concentration of the plate remain constant. Using initial and boundary conditions, partial differential equations were used to describe this phenomenon. Introduce some appropriate non-dimensional variables and utilize the Laplace transform method to solve the corresponding dimensionless equations. The following analytical remedies for heat, velocity and concentration profiles were produced in terms of exponential and (erfc) complementary error functions. A MATLAB programme is used to exhibit the results as graphs for various parameters. By creating graphs, we may assess the characteristics of the velocity, Heat and concentration while also studying the physical aspects for various factors

Chemical Reactive Flow past a Parabolic Vertical Plate with Exponentially Accelerated Temperature and Uniform Mass Transfer

The topic of flow across an infinitely wide parabolic vertical sheet with accelerating reactions of chemicals and heating is addressed in this article. The Laplace transform method is used to rectify the dimensioned equations that govern of movement into a set of non-dimensional regulating mathematical equations of motion. It is found that thermal energy as well as chemical responses have a substantial impact on the rates of both mass and heat transmission. Using analytical formulas, create temperatures, concentrations, and velocity personas. The physical aspects of various components, including acceleration (a), thermal radiation parameter (R), chemical reaction parameter (K), thermal Grashof number (Gr), mass Grashof number (Gc), Schmidt number (Sc), Prandtl number (Pr), and time variable (t) are investigated. By drawing graphs, characteristics of the velocity, temperature, and concentration are examined

On the stranding of sea cow Dugong dugon at Mandapam along the Gulf of Mannar coast.

A dead male sea cow Dugong dugon (Muller) measuring 194 cm in total length and about 125kg in weight was stranded along the Gulf of Mannar coast at Mandapam.The morphometric measurements of specimen were taken and identified to species level

Antagonistic potential of Trichoderma hamatum against Alternaria porri causing purple blotch disease of onion through Gas chromatography-mass spectrometry (GCMS) analysis

Alternaria porri causing purple blotch disease of onion is a destructive phytopathogen which causes severe loss in productivity. The present study aimed to unravel the antagonistic potential and efficacy of volatile organic compounds produced by various Trichoderma spp. against A. porri causing purple blotch disease of onion through Gas chromatography-mass spectrometry (GCMS) analysis. Ten isolates of Trichoderma species were isolated from the rhizospheric soil of healthy onion plants. Upon paired plate technique, the in vitro efficacy of ten Trichoderma isolates were tested against virulent isolate of Alternaria porri isolated from purple blotch disease infected onion plants. The Trichoderma isolate TIM2 showed 76.29 per cent inhibition on mycelial growth of pathogen. The effective Trichoderma isolate was identified as Trichoderma hamatum through the analysis of the rDNA of internal transcribed spacers (ITS) region and it was subjected to GC-MS analysis.  The result of GCMS analysis indicated the highest peak area and retention time with major antimicrobial bioactive compounds like Tetradecane, 2,6,10-trimethy (20.327), (1.22) and Dodecane, 2-cyclohexyl (20.079), (2.14), Heptadecane (21.222), (9.50), Octadecane (22.379), (3.58), Eicosane, 9-cyclohexyl (22.578), (1.84), 2-Propenoic acid, pentadecyl ester (23.400), (10.37), 2,6,10,14-tetramethyl (23.567), (10.37), Eicosane (27.311), (2.34), Hexadecanoic acid, methyl ester (27.918), (4.43), n-Hexadecanoic acid (29.156), (3.59) and  Tetrapentacontane, 1,54-dibromo (31.906), (3.33). These bioactive compounds identified through GCMS analysis from the crude extracts of Trichoderma hamatum exhibited a stronger antifungal activity against A. porri. Hence the application of T. hamatum for the management of purple blotch disease highly supress growth of the pathogen and reduce the disease incidence.