1,557 research outputs found
Geometrical constraints on dark energy models
This contribution intends to give a pedagogical introduction to the topic of
dark energy (the mysterious agent supposed to drive the observed late time
acceleration of the Universe) and to various observational tests which require
only assumptions on the geometry of the Universe. Those tests are the
supernovae luminosity, the CMB shift, the direct Hubble data, and the baryon
acoustic oscillations test. An historical overview of Cosmology is followed by
some generalities on FRW spacetimes (the best large-scale description of the
Universe), and then the test themselves are discussed. A convenient section on
statistical inference is included as well.Comment: 28 pages, 15 pages, lecture notes prepared for the ``Advanced Summer
School in Physics 2007" organized by Cinvestav (Mexico DF
Uso eficiente de aritmética redundante en FPGAs
Hasta hace pocos años, la utilización de aritmética redundante en FPGAs había
sido descartada por dos razones principalmente. En primer lugar, por el buen
rendimiento que ofrecían los sumadores de acarreo propagado, gracias a la lógica de
de acarreo que poseían de fábrica y al pequeño tamaño de los operandos en las
aplicaciones típicas para FPGAs. En segundo lugar, el excesivo consumo de área que
las herramientas de síntesis obtenían cuando mapeaban unidades que trabajan en carrysave.
En este trabajo, se muestra que es posible la utilización de aritmética redundante
carry-save en FPGAs de manera eficiente, consiguiendo un aumento en la velocidad de
operación con un consumo de recursos razonable. Se ha introducido un nuevo formato
redundante doble carry-save y se ha demostrado que la manera óptima para la
realización de multiplicadores de elevado ancho de palabra es la combinación de
multiplicadores empotrados con sumadores carry-save.Till a few years ago, redundant arithmetic had been discarded to be use in FPGA
mainly for two reasons. First, the efficient results obtained using carry-propagate adders
thanks to the carry-logic embedded in FPGAs and the small sizes of operands in typical
FPGA applications. Second, the high number of resources that the synthesis tools
utilizes to implement carry-save circuits.
In this work, it is demonstrated that carry-save arithmetic can be efficiently used
in FPGA, obtaining an important speed improvement with a reasonable area cost. A
new redundant format, double carry-save, has been introduced, and the optimal
implementation of large size multipliers has been shown based on embedded multipliers
and carry-save adders
Stop resisting! : an exploratory study of police brutality and its impacts on Black and Latino males, their communities, mental health and healing
The purpose of this qualitative research study was to explore the impacts of police violence on Black and Latino males and their communities while also examining avenues of healing that could be helpful for survivors. Generally, this study focused on this question: What is the potential mental health effect of police brutality on Black and Latino males and what are avenues for healing for those affected? Twelve individual participants who identified as activists, advocates, or organizers in the Bay Area of Northern California participated in qualitative interviews that explored the impact of police violence and healing avenues. Participants were asked about the long-term impacts of police brutality on Black and Latino males and their communities, trends of police violence, barriers to healing, and healing avenues for survivors of police violence.
Major findings of this study suggest that Black and Latino males who survive police violence experience high levels of repetitive trauma, feel a sense of powerlessness through their experiences, internalize negative identities through those experiences, and struggle to share their emotions and stories due to challenges to their masculinity. Additionally, findings suggested that Black and Latino males could benefit from specific healing avenues including healing circles, engaging in advocacy and activism, and receiving support from culturally syntonic healers. The findings indicate a need to look further into how police violence affects communities of color and encourages social workers to be attuned to specific healing avenues for those impacted
Bay leaves extracts as active additive for food protective coatings
Ethanolic extracts of bay leaves were obtained using the Soxhlet method (extraction yield of 22.3 ± 1.2%) and further analyzed through different methods, thus determining the chemical composition with gas chromatography, phenolic content with the Folin–Ciocalteu technique (11.8 ± 0.4% wt.) and antioxidant power with the radical 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) method (75.06%). Furthermore, its effect on the growth of two bacteria, Escherichia coli and Bacillus cereus, and on two yeasts, Candida glabrata and Saccharomyces cerevisiae, was determined, showing a minimum inhibitory concentration of 0.65 mg/mL on the growth of B. cereus. Finally, edible films were prepared using different polymers (carboxymethyl cellulose, gum Arabic, polyvinyl pyrrolidone, and polyvinyl alcohol) containing 0, 5, 10, or 15% wt. of bay leaf extract as troubleshooting for perishable fruits, specifically for cultivated strawberry. The prepared composites presented reduced water vapor permeabilities (up to 4.3 × 10−7 g·Pa−1·m−1·h−1), high specific transparencies (≈30%/mm), as well as the effective blocking of ultraviolet radiation (>99.9%). In vivo tests showed that the most suitable treatment for strawberry protection was the impregnation with a composite comprising polyvinyl alcohol and a 15% wt. bay leaf extract, resulting in a noteworthy reduction in mass loss (22% after 6 days). It can be asserted that food packaging with the designed composites would be an effective alternative for the reduction in postharvest losses
Educación y cultura popular: ensayo sobre las posibilidades educativas del folklore andino
El presente estudio es el producto de un equipo de antropólogos y sociólogos que puede ser tomado como el resultado de un esfuerzo para esbozar un modelo de aplicación antropológico. Intenta buscar en el mundo andino los contenidos del desarrollo curricular, en función de su propia cosmovisión. Este trabajo trata de escapar a la orientación educativa de espíritu colonial; e intenta convertir a la escuela en un lugar de encuentro recreativo y respetuoso de culturas y hombres diferentes
Phylogeny, Resistome, and Virulome of Escherichia coli Causing Biliary Tract Infections
Escherichia coli is the most frequent Gram-negative bacilli involved in intra-abdominal infections. However, despite high mortality rates associated with biliary tract infections due to E. coli, there is no study focusing on this pathogen. In this study, we have characterized a group of 15 E. coli isolates obtained from 12 patients with biliary tract infections. Demographic and clinical data of the patients were recovered. Phylogeny, resistome, and virulome analysis through whole genome sequencing and biofilm formation were investigated. Among the 15 E. coli isolates, no predominant sequence type (ST) was identified, although 3 of them belonged to unknown STs (20%). Resistance to ampicillin, amoxicillin/clavulanic acid, cotrimoxazole, and quinolones was more present in these isolates; whereas, third and fourth generation cephalosporins, carbapenems, amikacin, tigecycline, and colistin were highly active. Moreover, high diversity of virulence factors has been found, with sfa, fimH, and gad the most frequently detected genes. Interestingly, 26.6% of the E. coli isolates were high biofilm-producers. Altogether, our data characterized for the first time E. coli isolates associated with biliary tract infections in terms of genomic relationship, resistome, and virulome.España, Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Ciencia, Innovación y Universidades (CP15/00132)España, Plan Nacional de I+D+i 2013-2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Ciencia, Innovación y Universidades, Spanish Network for Research in Infectious Diseases (RD16/0016/0009
ADQPCI: Data Acquisition Board for Educational purposes
En este trabajo se presenta una de las placas de adquisición de datos que se ha desarrollado con fines docentes para su utilización en prácticas relacionadas con sistemas en tiempo real e
informática industrial y se plantean algunas de las ventajas e inconvenientes frente a la utilización
de placas comerciales. A lo largo del trabajo se detalla el diseño del hardware, en el que se ha
priorizado la facilidad de programación, siendo ésta una de las ventajas frente a las placas
comerciales. En estas prácticas es fundamental que el alumno tome conciencia de la importancia
de la interfaz hardware-software, si se quiere conseguir un sistema fiable y que explote al máximo
las características del hardware. Con el desarrollo de una placa de adquisición de datos se
consigue un sistema que el alumno puede utilizar en varias asignaturas de su titulación que están
relacionadas con el desarrollo y programación de sistemas empotrados.In this work a data acquisition board developed for educational use in subjects related to real-time
systems and industrial computing, is presented. The main advantages and disadvantages of using
these boards versus the use of commercial boards are discussed. The hardware design described
along this work emphasizes the facility of programming the board, which is one of the main
advantages versus the commercial boards. In these practices it is essential that student
comprehend the importance of the hardware-software interface in order to obtain a reliable system
which exploits in a maximum way the characteristics of the hardware. The development of a data
acquisition board allows to obtain a system that the students can use in several course during his
university career which are related to the development and programming of embedded system
Legal framework and scientific responsibilities during volcanic crises: the case of the El Hierro eruption (2011–2014)
In recent years concerns have been growing in the scientific community over the definition of scientific responsibilities during emergencies, and the legal status of scientists involved in the corresponding decision-making. It is clear that the legal framework is one of the main elements affecting this issue; however, many factors may affect both the specific scientific decision-making and the definition of general scientific responsibilities. The situation will vary depending on the type and scale of emergency, and from place to place, even in the same country. There will be no such thing as a single, ideal solution.
In the latest El Hierro volcanic crisis many factors have negatively affected the scientific management and have prevented an adequate definition of scientific responsibility. These factors have been detected and documented by the authors. They include excessive pressure due to human and economic issues, a poor legal framework with identifiable deficiencies, an Emergency Plan in which the Volcanic Activity/Alert Level (VAL), Emergency Response Level (ERL) and Volcanic Traffic Light (VTL) have been too rigidly linked, serious weaknesses in the management and structure of the Scientific Committee (SC), and more. Even though some of these problems have now been detected and certain solutions have already been proposed, the slowness and complexity of the bureaucratic processes are making it difficult to implement solutions.This research has been funded by the CSIC (201130E070) and MINECO (CGL2011-28682- C02-01) research projects.Peer reviewe
Restauración y actualización taxonómica de la colección de crustáceos (Arthropoda: Crustacea) de Juan C. Gundlach
Se presentan los resultados obtenidos al restaurar y actualizar la taxonomía de la colección de crustáceos cubanos realizada en el siglo XIX por el naturalista alemán, radicado en Cuba, Juan C. Gundlach. La misma está depositada en el Instituto de Ecología y Sistemática de Cuba y consta de dos (2) estomatópodos (Stomatopoda), cuatro (4) isópodos (Isopoda), 11 camarones (Penaeidae, Caridea, Stenopodidea), ocho langostas (Palinuridae, Scyllaridae), 14 anomuros (Porcellanidae, Hippidae, Coenobitidae, Diogenidae) y 37 braquiuros (Dromiidae, Calappidae, Carpiliidae, Eriphiidae, Menippidae Leucosiidae, Epialthidae; Majidae, Parthenopidae, Portunidae, Pseudothelpusidae, Panopeidae, Xanthidae, Gecarcinidae, Grapsidae, Plagusiidae, Ocypodidae, Ucididae). Se ofrece además, para cada especie, un vínculo de los nombres de aquella época con los actualmente válidos
Conformationally-Locked C-Glycosides: Tuning Aglycone Interactions for Optimal Cheperone Behaviour in Gaucher Fibroblasts
A series of conformationally locked C-glycosides based on the 3-aminopyrano[3,2-b]pyrrol-2(1H)-one (APP) scaffold has been synthesized. The key step involved a totally stereocontrolled C-Michael addition of a serine-equivalent C-nucleophile to tri-O-benzyl-2-nitro-D-galactal, previously published by the authors. Stereoselective transformations of the Michael adduct allowed us the synthesis of compounds with mono- or diantennated aglycone moieties and different topologies. In vitro screening showed highly selective inhibition of bovine liver β-glucosidase/β-galactosidase and specific inhibition of human β-glucocerebrosidase among lysosomal glycosidases for compounds bearing palmitoyl chains in the aglycone, with a marked dependence of the inhibition potency upon their number and location. Molecular dynamics simulations highlighted the paramount importance of an optimal orientation of the hydrophobic substituent to warrant efficient non-glycone interactions, which are critical for the binding affinity. The results provide a rationale for the strong decrease of the inhibition potency of APP compounds on going from neutral to acidic pH. The best candidate was found to behave as pharmacological chaperone in Gaucher fibroblasts with homozygous N370S and F213I mutations, with enzyme activity enhancements similar to those encountered for the reference compound AmbroxolMinisterio de Economía y Competitividad CTQ2012-36365, SAF2013-44021-RJunta de Andalucía FQM-1467European Union Seventh Framework Programme FP7-People-2012-CI
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