13,611 research outputs found
The invertebrate Caenorhabditis elegans biosynthesizes ascorbate.
l-Ascorbate, commonly known as vitamin C, serves as an antioxidant and cofactor essential for many biological processes. Distinct ascorbate biosynthetic pathways have been established for animals and plants, but little is known about the presence or synthesis of this molecule in invertebrate species. We have investigated ascorbate metabolism in the nematode Caenorhabditis elegans, where this molecule would be expected to play roles in oxidative stress resistance and as cofactor in collagen and neurotransmitter synthesis. Using high-performance liquid chromatography and gas-chromatography mass spectrometry, we determined that ascorbate is present at low amounts in the egg stage, L1 larvae, and mixed animal populations, with the egg stage containing the highest concentrations. Incubating C. elegans with precursor molecules necessary for ascorbate synthesis in plants and animals did not significantly alter ascorbate levels. Furthermore, bioinformatic analyses did not support the presence in C. elegans of either the plant or the animal biosynthetic pathway. However, we observed the complete (13)C-labeling of ascorbate when C. elegans was grown with (13)C-labeled Escherichia coli as a food source. These results support the hypothesis that ascorbate biosynthesis in invertebrates may proceed by a novel pathway and lay the foundation for a broader understanding of its biological role
Sea level height, sea surface temperature, and tuna yields in the Panama bight during El Niño
Between 1988 and 1998, annual tuna landings at Buenaventura (Colombian Pacific) are correlated with the sea surface temperature in the central Equatorial Pacific (<i>r</i>=0.78, <i>p</i><0.05) and the sea level height at Buenaventura (<i>r</i>=0.76, <i>p</i><0.05) and Balboa (Panama) (<i>r</i>=0.79, <i>p</i><0.05). Seasonal oceanic upwelling is forced by the Panama wind jet, which may favour oceanic fisheries such as tuna. Here we first apply a bivariate correlation method (Pyper and Peterman, 1994) and then a multivariate approach (principal components analysis or PCA) to investigate the relationships of these environmental variables with landings. With the first method, we find that landing is best correlated with the sea surface temperature in the Niño 3 region, whereas the other relationships are less clear. In contrast, with PCA we find that PC1 explains 90.6% of the total variance and suggests that sea surface temperature plays a major role in determining tuna availability in the area (especially during El Niño events). Since PC2 is mainly correlated with sea level height at Balboa but only represents 6.8% of the total variance, we suggest that oceanic upwelling effects on tuna landings at Buenaventura are not significant at interannual scales
Natural history of a visceral leishmaniasis outbreak in highland Ethiopia
In May 2005, visceral leishmaniasis (VL) was recognized for the first time in Libo Kemken, Ethiopia, a highland region where only few cases had been reported before. We analyzed records of VL patients treated from May 25, 2005 to December 13, 2007 by the only VL treatment center in the area, maintained by Médecins Sans Frontières-Ethiopia, Operational Center Barcelona-Athens. The median age was 18 years; 77.6% were male. The overall case fatality rate was 4%, but adults 45 years or older were five times as likely to die as 5-29 year olds. Other factors associated with increased mortality included HIV infection, edema, severe malnutrition, pneumonia, tuberculosis, and vomiting. The VL epidemic expanded rapidly over a several-year period, culminating in an epidemic peak in the last third of 2005, spread over two districts, and transformed into a sustained endemic situation by 2007
Action-Research, Professional Development of the Physical Education Teachers in Rural Schools
La finalidad de este estudio es analizar la influencia de un grupo de trabajo de Investigación-Acción en el desarrollo profesional de maestros de Educación Física (EF) que ejercen su labor docente en la Escuela Rural.
El diseño es un estudio multicaso. Para la recogida de datos se utilizaron: historias de vida, entrevistas en profundidad, análisis de documentos y diario de investigación. El análisis de datos se realizó a través de un proceso de categorización.
Los resultados muestran que: (a)-los maestros de EF que ejercen su labor docente en la escuela rural pasan por situaciones difíciles y complicadas los primeros años, y que la pertenencia a grupos de Investigación-Acción les
ayuda a que la adaptación a este contexto educativo sea más rápida y fácil; (b)-la metodología de Investigación-Acción genera procesos de reflexión que ayudan a mejorar su práctica docente, influye positivamente en su desarrollo profesional y supone un apoyo.The purpose of this paper is to analyze the influence of a Action Research group on professional development of physical education (PE) teachers in rural school. The research methodology used was case study. Data collection was conducted through interviews, life stories, document analysis and research notebook. Data analysis was performed through a categorization process.
The results show that: (a)-PEF teachers in rural school engaged in difficult situations at early years, and to be a membership of Action Research group helps them adapt to this context educational faster and easier, (b)-the Action Research methodology generates reflective processes that help improve their teaching, has a positive influence on their professional development and represent a suppor
Controlled Irradiative Formation of Penitentes
Spike-shaped structures are produced by light-driven ablation in very
different contexts. Penitentes 1-4 m high are common on Andean glaciers, where
their formation changes glacier dynamics and hydrology. Laser ablation can
produce cones 10-100 microns high with a variety of proposed applications in
materials science. We report the first laboratory generation of
centimeter-scale snow and ice penitentes. Systematically varying conditions
allows identification of the essential parameters controlling the formation of
ablation structures. We demonstrate that penitente initiation and coarsening
requires cold temperatures, so that ablation leads to sublimation rather than
melting. Once penitentes have formed, further growth of height can occur by
melting. The penitentes intially appear as small structures (3 mm high) and
grow by coarsening to 1-5 cm high. Our results are an important step towards
understanding and controlling ablation morphologies.Comment: Accepted for publication in Physical Review Letter
Privacy-by-design rules in face recognition system
In this paper, we develop a face recognition system based on softcomputing techniques, which complies with privacy-by-design rules and defines a set of principles that are context-aware applications (including biometric sensors) and should contain to conform to European and US law. This paper deals with the necessity to consider legal issues concerning privacy or human rights in the development of biometric identification in ambient intelligence systems. Clearly, context-based services and ambient intelligence (and the most promising research area in Europe, namely ambient assisted living, ALL) call for a major research effort on new identification procedures.This work was supported in part by Projects CICYT TIN 2011-28620-C02-01, CICYT TEC2011-28626-C02-02, CAM CONTEXTS (S2009/TIC-1485) and DPS2008-07029-C02-02.Publicad
Effects Of Changes In Conditioning Regimen And Supportive Care On Outcomes In Patients With Acute Myeloid Leukemia (AML) After Allogeneic Stem Cell Transplantation (Allo-SCT)
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