2,105 research outputs found
SJM: Un simulador de jerarquÃas de memoria orientado a la docencia de arquitectura de computadores
El concepto de jerarquÃa de memoria de un computador
es uno de los más importantes en el ámbito de
la docencia en arquitectura de computadores. Habitualmente,
los distintos aspectos de la estructura y el
funcionamiento de la jerarquÃa de memoria (memoria
cache, memoria virtual, algoritmos de reemplazo,
tasas de fallos, etc.) se explican primero a los alumnos
de manera teórica, y posteriormente se realizan
prácticas basadas en programas que simulan dicha
jerarquÃa.
En este trabajo se presenta un nuevo simulador pedagógico,
SJM, que permite modelar de forma amigable
distintas jerarquÃas de memoria, modificar fácilmente
sus caracterÃsticas y obtener medidas de sus
prestaciones, de cara a que los alumnos, mediante
la evaluación de distintas configuraciones de la jerarquÃa
de memoria, afiancen su comprensión de los
distintos aspectos de ésta.Peer Reviewe
Mean Sombor index
A Special Volume on Chemical Graph Theory in Memory of Nenad TrinajsticWe introduce a degree–based variable topological index inspired on the power (or generalized) mean. We name this new index as the mean Sombor index: SOα(G) = P uv∈E(G) [(d α u + d α v ) /2]1/α. Here, uv denotes the edge of the graph G connecting the vertices u and v, du is the degree of the vertex u, and α ∈ R\{0}. We also consider the limit cases mSOα→0(G) and
SOα→±∞(G). Indeed, for given values of α, the mean Sombor index is related to well-known opological indices such as the inverse sum indeg index, the reciprocal Randic index, the first Zagreb index, the Stolarsky–Puebla index and several ´Sombor indices. Moreover, through a quantitative structure property relationship (QSPR) analysis we show that mSOα(G) correlates well with several physicochemical properties of octane isomers. Some mathematical properties of the mean Sombor index as well as bounds and new relationships with known topological indices are also discussed.J.A.M.-B. acknowledges financial support from CONACyT (Grant No. A1-S-22706) and BUAP (Grant No. 100405811VIEP2021) .E.D.M. and J.M.R. were supported by a grant from Agencia Estatal de Investigación (PID 2019-106433GBI00 / AEI / 10.13039 / 501100011033), Spain. J.M.R. was supported by the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M23), and in the context of the VPRICIT (Regional Programme of Research and Technological Innovation)
SJM: Un simulador de jerarquÃas de memoria orientado a la docencia de arquitectura de computadores
El concepto de jerarquÃa de memoria de un computador es uno de los más importantes en el ámbito de la docencia en arquitectura de computadores. Habitualmente, los distintos aspectos de la estructura y el funcionamiento de la jerarquÃa de memoria (memoria cache, memoria virtual, algoritmos de reemplazo, tasas de fallos, etc.) se explican primero a los alumnos de manera teórica, y posteriormente se realizan prácticas basadas en programas que simulan dicha jerarquÃa. En este trabajo se presenta un nuevo simulador pedagógico, SJM, que permite modelar de forma amigable distintas jerarquÃas de memoria, modificar fácilmente sus caracterÃsticas y obtener medidas de sus prestaciones, de cara a que los alumnos, mediante la evaluación de distintas configuraciones de la jerarquÃa de memoria, afiancen su comprensión de los distintos aspectos de ésta
Orbital and physical properties of the sigma Ori Aa, Ab, B triple system
We provide a complete characterization of the astrophysical properties of the sigma Ori Aa, Ab, B hierarchical triple system and an improved set of orbital parameters for the highly eccentric sigma Ori Aa, Ab spectroscopic binary. We compiled a spectroscopic data set comprising 90 high-resolution spectra covering a total time span of 1963 days. We applied the Lehman-Filhes method for a detailed orbital analysis of the radial velocity curves and performed a combined quantitative spectroscopic analysis of the sigma Ori Aa, Ab, B system by means of the stellar atmosphere code FASTWIND. We used our own plus other available information on photometry and distance to the system for measuring the radii, luminosities, and spectroscopic masses of the three components. We also inferred evolutionary masses and stellar ages using the Bayesian code BONNSAI. The orbital analysis of the new radial velocity curves led to a very accurate orbital solution of the sigma Ori Aa, Ab pair. We provided indirect arguments indicating that sigma Ori B is a fast-rotating early B dwarf. The FASTWIND+BONNSAI analysis showed that the Aa, Ab pair contains the hottest and most massive components of the triple system while sigma Ori B is a bit cooler and less massive. The derived stellar ages of the inner pair are intriguingly younger than the one widely accepted for the sigma Orionis cluster, at 3 +/- 1 Ma. The outcome of this study will be of key importance for a precise determination of the distance to the s Orionis cluster, the interpretation of the strong X-ray emission detected for sigma Ori Aa, Ab, B, and the investigation of the formation and evolution of multiple massive stellar systems and substellar objects
Intelligent Financial Fraud Detection Practices: An Investigation
Financial fraud is an issue with far reaching consequences in the finance
industry, government, corporate sectors, and for ordinary consumers. Increasing
dependence on new technologies such as cloud and mobile computing in recent
years has compounded the problem. Traditional methods of detection involve
extensive use of auditing, where a trained individual manually observes reports
or transactions in an attempt to discover fraudulent behaviour. This method is
not only time consuming, expensive and inaccurate, but in the age of big data
it is also impractical. Not surprisingly, financial institutions have turned to
automated processes using statistical and computational methods. This paper
presents a comprehensive investigation on financial fraud detection practices
using such data mining methods, with a particular focus on computational
intelligence-based techniques. Classification of the practices based on key
aspects such as detection algorithm used, fraud type investigated, and success
rate have been covered. Issues and challenges associated with the current
practices and potential future direction of research have also been identified.Comment: Proceedings of the 10th International Conference on Security and
Privacy in Communication Networks (SecureComm 2014
Estudio molecular de las proteÃnas p y t constituyentes del sistema de clivaje de la glicina en pacientes con diagnóstico presuntivo de hiperglicinemia no cetósica (hnc)
Analizar por medio de métodos moleculares el defecto enzimático en las proteÃnas P y T constituyentes del complejo enzimático del clivaje de la glicina. Establecer estrategias de biologÃa molecular que permitan  identificar la mutación que afecta las proteÃnas P y T
Estudio molecular de las proteÃnas p y t constituyentes del sistema de clivaje de la glicina en pacientes con diagnóstico presuntivo de hiperglicinemia no cetósica (hnc)
Analizar por medio de métodos moleculares el defecto enzimático en las proteÃnas P y T constituyentes del complejo enzimático del clivaje de la glicina. Establecer estrategias de biologÃa molecular que permitan  identificar la mutación que afecta las proteÃnas P y T
Dissimilar Impact of a Mediterranean Diet and Physical Activity on Anthropometric Indices: A Cross-Sectional Study from the ILERVAS Project
There is a close relationship between lifestyle behaviors and excess adiposity. Although body mass index (BMI) is the most used approach to estimate excess weight, other anthropometric indices have been developed to measure total body and abdominal adiposity. However, little is known about the impact of physical activity and adherence to a Mediterranean diet on these indices. Here we report the results of a cross-sectional study with 6672 middle-aged subjects with low to moderate cardiovascular risk from the Ilerda Vascular (ILERVAS) project. The participants' adherence to physical activity (International Physical Activity Questionnaire short form) and MedDiet (Mediterranean Diet Adherence Screener) was evaluated. Measures of total adiposity (BMI, ClÃnica Universidad de Navarra-Body Adiposity Estimator (CUN-BAE), and Deurenberg's formula), central adiposity (waist and neck circumferences, conicity index, waist to height ratio, Bonora's equation, A body adiposity index, and body roundness index), and lean body mass (Hume formula) were assessed. Irrespective of sex, lower indices of physical activity were associated with higher values of total body fat and central adiposity. This result was constant regardless of the indices used to estimate adiposity. However, the association between MedDiet and obesity indices was much less marked and more dependent on sex than that observed for physical activity. Lean body mass was influenced by neither physical activity nor MedDiet adherence. No joint effect between physical activity and MedDiet to lower estimated total or central adiposity indices was shown. In conclusion, physical activity is related to lower obesity indices in a large cohort of middle-aged subjects. MedDiet showed a slight impact on estimated anthropometric indices, with no joint effect when considering both lifestyle variables
Anti-microbiota vaccines modulate the tick microbiome in a taxon-specific manner
The lack of tools for the precise manipulation of the tick microbiome is currently a major limitation to achieve mechanistic insights into the tick microbiome. Anti-tick microbiota vaccines targeting keystone bacteria of the tick microbiota alter tick feeding, but their impact on the taxonomic and functional profiles of the tick microbiome has not been tested. In this study, we immunized a vertebrate host model (Mus musculus) with live bacteria vaccines targeting keystone (i.e., Escherichia-Shigella) or non-keystone (i.e., Leuconostoc) taxa of tick microbiota and tested the impact of bacterial-specific antibodies (Abs) on the structure and function of tick microbiota. We also investigated the effect of these anti-microbiota vaccines on mice gut microbiota composition. Our results showed that the tick microbiota of ticks fed on Escherichia coli-immunized mice had reduced Escherichia-Shigella abundance and lower species diversity compared to ticks fed on control mice immunized with a mock vaccine. Immunization against keystone bacteria restructured the hierarchy of nodes in co-occurrence networks and reduced the resistance of the bacterial network to taxa removal. High levels of E. coli-specific IgM and IgG were negatively correlated with the abundance of Escherichia-Shigella in tick microbiota. These effects were not observed when Leuconostoc was targeted with vaccination against Leuconostoc mesenteroides. Prediction of functional pathways in the tick microbiome using PICRUSt2 revealed that E. coli vaccination reduced the abundance of lysine degradation pathway in tick microbiome, a result validated by qPCR. In contrast, the gut microbiome of immunized mice showed no significant alterations in the diversity, composition and abundance of bacterial taxa. Our results demonstrated that anti-tick microbiota vaccines are a safe, specific and an easy-to-use tool for manipulation of vector microbiome. These results guide interventions for the control of tick infestations and pathogen infection/transmission. © Copyright © 2021 Mateos-Hernández, Obregón, Wu-Chuang, Maye, Bornères, Versillé, de la Fuente, DÃaz-Sánchez, Bermúdez-Humarán, Torres-Maravilla, Estrada-Peña, Hodžic, Å imo and Cabezas-Cruz
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