2,791 research outputs found
Cost of AIDS care in Mexico: what are its main individual predictors?
BACKGROUND: The Mexican government is offering universal access to antiretroviral (ARV) drugs. The cost of doing so, despite aggressive price negotiation with the pharmaceutical industry, remains high. Even with a low prevalence, about 150,000 Mexicans are estimated to be living with HIV and will require ARV treatment. Estimating the resources needed to fund this gap should consider how patient and provider characteristics affect health care costs. METHODS: Using a sample of patients from 11 facilities in three Mexican cities representing a large proportion of AIDS patients in the country, we developed a fixed-effect model, which by controlling the facilities and individual heterogeneity estimates predicted costs using patient demographic and socioeconomic characteristics as well as physician training. RESULTS: The estimated model explains about 45% of the variation in costs. Additional education is significantly and positively associated with cost. Increasing age is also associated with higher costs. CONCLUSIONS: Socioeconomic status and demographic characteristics explain an important proportion of variation in care costs for AIDS, despite AIDS being such a heterogeneous disease. Such characteristics will need to be taken into account when resource needs are estimated. A priority-setting process considering the principles of equity in the fair distribution of resources is needed to help reduce the social burden of HIV/AIDS in Mexico
Ofuscación de código utilizando generadores de números pseudoaleatorios
We describe a novel method for malicious code obfuscation that uses code already present in systems: a pseudo-random number generator. This can also be seen as an antidisassembly and anti-debugging technique, depending on deploy- ment, because the actual code does not exist until run – it is generated dynamically by the pseudo-random number generator. A year’s worth of experiments are used to demonstrate that this technique is a viable code obfuscation option for a malicious adversary with access to large amounts of computing power.Se describe un nuevo método para la ofuscación de códigos maliciosos que utiliza códigos ya presentes en los sistemas: un generador de números pseudo-aleatorios. Esto también puede verse como una técnica anti-desmontaje y anti-depuración, dependiendo de su despliegue, debido a que el código real no existe hasta su ejecución - que se genera de forma dinámica por el generador de números pseudo-aleatorios. Se han usado xperimentos de todo un año para demostrar que esta técnica de ofuscación es viable para un adversario malicioso con acceso a una gran potencia computacional.
Continuous harmonic analysis and power quality measurements in three-phase systems
A virtual instrument, named Power Quality
Meter, is presented for (a) measuring power consumption and
harmonics in three-phase systems, under non-sinusoidal and
imbalance conditions (b) detecting, classifying and organizes
power disturbance events. Measurement of the power
consumption follows the formulation proposed by the members
of the IEEE Working Group on Nonsinusoidal Situations
(1996). So, definitions are based on the analysis of functions in
the frequency domain, separating the fundamental terms from
the harmonic terms of the Fourier series. The virtual instrument
has been developed too for monitoring and measuring power
disturbances, which are automatically classified and organized
in a database while they are being recorded. Software tools use
the database structure to present summaries of power
disturbances and locate an event by severity or time of
occurrence. Records of actual measurements are included to
demonstrate the versatility of the instrument
Toward an automatic full-wave inversion: Synthetic study cases
Full-waveform inversion (FWI) in seismic scenarios continues to be a complex procedure for subsurface imaging that might require extensive human interaction in terms of model setup, constraints, and data preconditioning. The underlying reason is the strong nonlinearity of the problem that forces the addition of a priori knowledge (or bias) in order to obtain geologically sound results. In particular, when the use of a long-offset receiver is not possible or may not favor the reconstruction of the fine structure of the model, one needs to rely on reflection data. As a consequence, the inversion process is more prone to becoming stuck in local minima. Nevertheless, misfit functionals can be devised that can either cope with missing long-wavenumber features of initial models (e.g., cross-correlation-based misfit) or invert reflection-dominated data whenever the models are sufficiently good (e.g., normalized offset-limited least-squares misfit). By combining both, high-frequency data content with poor initial models can be successfully inverted. If one can figure out simple parameterizations for such functionals, the amount of uncertainty and manual work related to tuning FWI would be substantially reduced. Thus, FWI might become a semiautomatized imaging tool.We want to thank Repsol for funding this research by means of the Aurora project. This
project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 644202. Additionally, the research leading to these results has received funding from the European Union’s Horizon 2020 Programme (2014-2020) and from Brazilian Ministry of Science, Technology and Innovation
through Rede Nacional de Pesquisa (RNP) under the HPC4E Project (www.hpc4e.eu), grant agreement No 689772. We acknowledge Chevron for the dataset that was used in our second example.Peer ReviewedPostprint (author's final draft
A photometric study of Be stars located in the seismology fields of COROT
Context. In preparation for the COROT mission, an exhaustive photometric study of Be stars located in the seismology fields of the mission has been performed. The very precise and long-time-spanned photometric observations gathered by the COROT satellite will give important clues on the origin of the Be phenomenon. Aims. The aim of this work is to find short-period variable Be stars located in the seismology fields of COROT, and to study and characterise their pulsational properties.
Methods. Light curves obtained at the Observatorio de Sierra Nevada, together with data from Hipparcos and ASAS-3 for a total of 84 Be stars, were analysed in order to search for short-term variations. We applied standard Fourier techniques and non-linear least-square fitting to the time series. Results. We found 7 multiperiodic, 21 mono-periodic and 26 non-variable Be stars. Short-term variability was detected in 74% of early-type Be stars and in 31% of mid- to late-type Be stars. We show that non-radial pulsations are more frequent among Be stars than in slow-rotating B stars of the same spectral [email protected]; [email protected]
Hidrógeno electrolítico para la gestión de la red eléctrica
La variabilidad de la demanda a lo largo de las horas del día y las estaciones del año, junto a la generación aleatoria de la mayoría de las fuentes de energía renovable, sitúan al sistema eléctrico ante un nuevo y fascinante paradigma; ello resulta especialmente relevante en redes relativamente aisladas y con una notable penetración de los parques eólicos, como sucede actualmente en España. La figura 1 muestra una curva típica, con dos puntas que reflejan sobretodo las necesidades de climatización durante las horas cálidas del estío e iluminación en los días cortos del invierno
Hydrotreating of Guaiacol and Acetic Acid Blends over Ni2P/ZSM-5 Catalysts: Elucidating Molecular Interactions during Bio-Oil Upgrading
[EN] Catalytic hydrodeoxygenation (HDO) is an effective technology for upgrading pyrolysis bio-oils. Although, in the past years, this process has been extensively studied, the relevance of the cross-reactivity between the numerous chemical components of bio-oil has been scarcely explored. However, molecular coupling can be beneficial for improving the bio-oil characteristics. With the aim of gaining a better understanding of these interactions, this work investigates the catalytic hydrodeoxygenation of mixtures of two typical components of pyrolysis bio-oils: guaiacol and acetic acid. The catalytic tests were carried out employing a bifunctional catalyst based on nickel phosphide (Ni2P) deposited over a commercial nanocrystalline ZSM-5 zeolite. The influence of both hydrogen availability and temperature on the activity and product distribution, was evaluated by carrying out reactions under different H2 pressures (40¿10 bar) and temperatures (between 260 and 300 °C). Using blends of both substrates, a partial inhibition of guaiacol HDO occurred because of the competence of acetic acid for the catalytic active sites. Nevertheless, positive interactions were also observed, mainly esterification and acylation reactions, which could enhance the bio-oil stability by reducing acidity, lowering the oxygen content, and increasing the chain length of the components. In this respect, formation of acetophenones, which can be further hydrogenated to yield ethyl phenols, is of particular interest for biorefinery applications. Increasing the temperature results in an increment of conversion but a decrease in the yield of fully deoxygenated molecules due to the production of higher proportion of catechol and related products. Additional experiments performed in the absence of hydrogen revealed that esterification reactions are homogeneously self-catalyzed by acetic acid, while acylation processes are mainly catalyzed by the acidic sites of the zeolitic support.The authors thank to the Spanish “Ministry of Economy and Competiveness” for their financial support through the project CATPLASBIO (CTQ2014-60209-R), as well as to the “Regional Government of Madrid” and European Structural Funds for the RESTOENE2 (S2013/MAE-2882) project
Metodología de evaluación continua en la asignatura de Fundamentos de Programación: un cambio de evaluación enfocado al desarrollo de competencias
El marco del Espacio Europeo de Educación Superior
(EEES) y la implantación del Sistema de Crédito
Europeo (ECTS) han motivado un cambio en el modelo
educativo. De un modelo basado en clases magistrales
se ha evolucionado hacia un modelo basado
en el aprendizaje por competencias del alumnado.
Esto implica un cambio en el sistema de evaluación.
Este trabajo expone la experiencia negativa vivida
el primer año de la asignatura de Fundamentos de
la Programación (FP) en los nuevos Grados de Ingeniería
Informática de la Escuela Técnica Superior
de Ingeniería Informática (ETSII) de la Universidad
de Sevilla (US). La experiencia negativa se produjo
por una sobre-evaluación del alumnado fruto de una
planificación de evaluación un tanto excesiva. Como
consecuencia de esta experiencia negativa, se decidió
realizar una nueva planificación de evaluación
continua de competencias adquiridas. Esta planificación
se está llevando a cabo en la actualidad y en
este artículo presentamos las conclusiones parciales.SUMMARY -- The European Higher Education Area and the implantation
of the European Credit Transfer System
have promoted a change in the educational model
and, hence, a change in the evaluation system. This
paper describes the negative experience in the first
year of the course Fundamentals of Programming in
the new Computer Science Degrees at University of
Seville. The negative experience has been an overevaluation
of the students caused by an excessive
evaluation planning. To overcome this negative experience,
a new plan of continuous assessment of
skills is planned. This plan is being implemented at
present and the partial conclusions obtained are described
in this paper.Peer Reviewe
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