10,954 research outputs found
A Practical Environment to Apply Model-Driven Web Engineering
The application of a model-driven paradigm in the development of Web Systems has yielded very good research
results. Several research groups are defining metamodels, transformations, and tools which offer a suitable environment,
known as model-driven Web engineering (MDWE). However, there are very few practical experiences in real
Web system developments using real development teams. This chapter presents a practical environment of MDWE
based on the use of NDT (navigational development techniques) and Java Web systems, and it provides a practical
evaluation of its application within a real project: specialized Diraya.Ministerio de Educación y Ciencia TIN2007-67843-C06-03Ministerio de Educación y Ciencia TIN2007-30391-
Existence and topological stability of Fermi points in multilayered graphene
We study the existence and topological stability of Fermi points in a
graphene layer and stacks with many layers. We show that the discrete
symmetries (spacetime inversion) stabilize the Fermi points in monolayer,
bilayer and multilayer graphene with orthorhombic stacking. The bands near
and in multilayers with the Bernal stacking depend on the
parity of the number of layers, and Fermi points are unstable when the number
of layers is odd. The low energy changes in the electronic structure induced by
commensurate perturbations which mix the two Dirac points are also
investigated.Comment: 6 pages, 6 figures. Expanded version as will appear in PR
Adding Recognition Discriminability Index to the Delayed Recall Is Useful to Predict Conversion from Mild Cognitive Impairment to Alzheimer's Disease in the Alzheimer's Disease Neuroimaging Initiative
Background: Ongoing research is focusing on the identification of those individuals with mild cognitive impairment (MCI) who are most likely to convert to Alzheimer's disease (AD). We investigated whether recognition memory tasks in combination with delayed recall measure of episodic memory and CSF biomarkers can predict MCI to AD conversion at 24-month follow-up. Methods: A total of 397 amnestic-MCI subjects from Alzheimer's disease Neuroimaging Initiative were included. Logistic regression modeling was done to assess the predictive value of all RAVLT measures, risk factors such as age, sex, education, APOE genotype, and CSF biomarkers for progression to AD. Estimating adjusted odds ratios was used to determine which variables would produce an optimal predictive model, and whether adding tests of interaction between the RAVLT Delayed Recall and recognition measures (traditional score and d-prime) would improve prediction of the conversion from a-MCI to AD. Results: 112 (28.2%) subjects developed dementia and 285 (71.8%) subjects did not. Of the all included variables, CSF Aβ1-42 levels, RAVLT Delayed Recall, and the combination of RAVLT Delayed Recall and d-prime were predictive of progression to AD (χ2 = 38.23, df = 14, p < 0.001). Conclusions: The combination of RAVLT Delayed Recall and d-prime measures may be predictor of conversion from MCI to AD in the ADNI cohort, especially in combination with amyloid biomarkers. A predictive model to help identify individuals at-risk for dementia should include not only traditional episodic memory measures (delayed recall or recognition), but also additional variables (d-prime) that allow the homogenization of the assessment procedures in the diagnosis of MCI.Fil: Russo, MarÃa Julieta. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Campos, Jorge. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; ArgentinaFil: Vázquez, Silvia. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; ArgentinaFil: Sevlever, Gustavo. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Allegri, Ricardo Francisco. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
A Practical Example for Model-Driven Web Requirements
The number of approaches for Web environments has grown very fast
in the last years: HDM, OOHDM, and WSDM were among the first, and now a
large number can be found in the literature. With the definition of MDA (Model-
Driven Architecture) and the acceptance of MDE (Model-Driven Engineering)
techniques in this environment, some groups are working in the use of metamodels
and transformations to make their approaches more powerful. UWE (UMLBased
Web Engineering) or OOWS (Object-Oriented Web Solutions) are only
some examples. However, there are few real experiences with Web Engineering in
the enterprise environment, and very few real applications of metamodels and
MDE techniques. In this chapter the practical experience of a Web Engineering
approach, NDT, in a big project developed in Andalusia is presented. Besides, it
shows the usability of metamodels in real environments
Classification, characterisation and strategies for improvement of cattle and sheep pasture systems in marginal areas of Southern Chile
Pasture-based livestock systems in farms with medium or low size are especially important in less favored areas and are valuable for society. For these systems to survive, it is necessary to obtain an acceptable level of productivity and ensure commercialization of the products. This study was carried out in the district of Rio Ibáñez, General Carrera Province, in the XI (Aysén) Region of Chile. The sample consisted of 28 small-scale livestock farmers with dual-purpose cattle production; 16 of them also produced sheep for meat. The empirical data produced 55 variables which were subjected to multivariate analysis; three main components were obtained which explain 72.1 % of the variance. By cluster analysis it was obtained four groups with characteristics which varied by farm size, age and personal situation of farmers, farm management and farm profitability. The principal problems found are low productivity in the herds and the poor marketing channels of animals produced. In two groups, due to the low size and poor management, the profitability of the farms is very low and this may compromise their future. To improve production systems, the training and advice of farmers should be strengthened, investment should be supported, especially for young people, and the farmer partnership should be promoted. There is also a need to diversify the families' sources of income (sale of other farm products or handicrafts and touristic activities).Ministerio de EconomÃa de Chile Innova-CORFO Project 11 NTEC 1279
Classification, characterisation and strategies for improvement of cattle and sheep pasture systems in marginal areas of Southern Chile
Pasture-based livestock systems in farms with medium or low size are especially important in less favored areas and are valuable for society. For these systems to survive, it is necessary to obtain an acceptable level of productivity and ensure commercialization of the products. This study was carried out in the district of Rio Ibáñez, General Carrera Province, in the XI (Aysén) Region of Chile. The sample consisted of 28 small-scale livestock farmers with dual-purpose cattle production; 16 of them also produced sheep for meat. The empirical data produced 55 variables which were subjected to multivariate analysis; three main components were obtained which explain 72.1 % of the variance. By cluster analysis it was obtained four groups with characteristics which varied by farm size, age and personal situation of farmers, farm management and farm profitability. The principal problems found are low productivity in the herds and the poor marketing channels of animals produced. In two groups, due to the low size and poor management, the profitability of the farms is very low and this may compromise their future. To improve production systems, the training and advice of farmers should be strengthened, investment should be supported, especially for young people, and the farmer partnership should be promoted. There is also a need to diversify the families' sources of income (sale of other farm products or handicrafts and touristic activities).Ministerio de EconomÃa de Chile Innova-CORFO Project 11 NTEC 1279
Testing Supersymmetry with Lepton Flavor Violating tau and mu decays
In this work the following lepton flavor violating and decays
are studied: , , , , and . We work in a supersymmetric scenario consisting of the minimal
supersymmetric standard model particle content, extended by the addition of
three heavy right handed Majorana neutrinos and their supersymmetric partners,
and where the generation of neutrino masses is done via the seesaw mechanism.
Within this context, a significant lepton flavor mixing is generated in the
slepton sector due to the Yukawa neutrino couplings, which is transmited from
the high to the low energies via the renormalization group equations. This
slepton mixing then generates via loops of supersymmetric particles significant
contributions to the rates of and the correlated decays. We analize here in full detail these rates in terms of the
relevant input parameters, which are the usual minimal supergravity parameters
and the seesaw parameters. For the decays, a full one-loop
analytical computation of all the contributing supersymmetric loops is
presented. This completes and corrects previous computations in the literature.
In the numerical analysis compatibility with the most recent experimental upper
bounds on all these and decays, with the neutrino data, and with
the present lower bounds on the supersymmetric particle masses are required.
Two typical scenarios with degenerate and hierarchical heavy neutrinos are
considered. We will show here that the minimal supergravity and seesaw
parameters do get important restrictions from these and decays in
the hierarchical neutrino case.Comment: Version to appear in Physical Review
Competencia financiera y modelación matemática en bachillerato: un acercamiento cualitativo desde la investigación basada en diseño (DBR)
La competencia matemática se articula como un conjunto de habilidades y capacidades que van permitir a los individuos analizar, resolver e interpretar problemas matemáticos en diferentes situaciones, y su importancia para mejorar el bienestar de los ciudadanos se recoge en informes como PISA o leyes como la LOMCE. El estudio del proceso de adquisición de la competencia financiera al trabajar dicha competencia con las competencias matemática y de modelación, es uno de los objetivos centrales de nuestra investigación, que se desarrolla en un contexto de enseñanza de EconomÃa en Bachillerato
Análisis de la formación matemática en los actuales grados en administración y dirección de empresas
La matematización de la economÃa y de la empresa –entendiendo por tal, tanto el uso de las matemáticas como herramienta auxiliar en los razonamientos deductivos que aparecen en los modelos teóricos económicos y de gestión empresarial, como el contraste empÃrico, por medio de la estadÃstica, de las diversas modelizaciones económico-empresariales− ha sido el centro del eterno debate entre los que están a favor y en contra del uso de las matemáticas en esta ciencia social. En la actualidad, se entiende generalizadamente que las matemáticas, dentro del ámbito de la economÃa y de la gestión de empresas, deben dar soporte a la modelización económica, entendida como modelización cuantitativa de la realidad económica y empresarial, aprovechando las ventajas del enfoque matemático a la hora de la búsqueda del conocimiento económico
Effects of radio-frequency fields on bacterial cell membranes and nematode temperature-sensitive mutants
Membrane-related bioeffects have been reported in response to both radio-frequency (RF) and extremely low-frequency (ELF) electromagnetic fields (EMFs), particularly in neural cells. We have tested whether RF fields might cause inner membrane leakage in ML35 E. coli cells, which express β-galactosidase (lacZ) constitutively, but lack the lacY permease required for substrate entry. The activity of lacZ (indicating substrate leakage through the inner cell membrane) was increased only slightly by RF exposure (1 GHz, 0.5 W) over 45 min. Since lacZ activity showed no further increase with a longer exposure time of 90 min, this suggests that membrane permeability per se is not significantly affected by RF fields, and that slight heating (≤ 0.1°C) could account for this small difference. Temperature-sensitive (ts) mutants of the nematode, Caenorhabditis elegans, are wild-type at 15°C but develop the mutant phenotype at 25°C; an intermediate temperature of 21°C results in a reproducible mixture of both phenotypes. For two ts mutants affecting transmembrane receptors (TRA-2 and GLP-1), RF exposure for 24 h during the thermocritical phase strongly shifts the phenotype mix at 21°C towards the mutant end of the spectrum. For ts mutants affecting nuclear proteins, such phenotype shifts appear smaller (PHA-1) or non-significant (LIN-39), apparently confirming suggestions that RF power is dissipated mainly in the plasma membrane of cells. However, these phenotype shifts are no longer seen when microwave treatment is applied at 21°C in a modified exposure apparatus that minimises the temperature difference between sham and exposed conditions. Like other biological effects attributed to microwaves in the C. elegans system, phenotype shifts in ts mutants appear to be an artefact caused by very slight heating
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