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Search Results: 1 - 10 of 373120 matches for " D. Balaguer Ríos "
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Realtime calibration of the A4 electromagnetic lead fluoride calorimeter
S. Baunack,D. Balaguer Ríos,L. Capozza,J. Diefenbach,R. Frascaria,B. Gl?ser,D. v. Harrach,Y. Imai,R. Kothe,R. Kunne,J. H. Lee,F. E. Maas,M. C. Mora Espí,M. Morlet,S. Ong,E. Schilling,J. van de Wiele,C. Weinrich
Physics , 2011, DOI: 10.1016/j.nima.2011.02.099
Abstract: Sufficient energy resolution is the key issue for the calorimetry in particle and nuclear physics. The calorimeter of the A4 parity violation experiment at MAMI is a segmented calorimeter where the energy of an event is determined by summing the signals of neighbouring channels. In this case the precise matching of the individual modules is crucial to obtain a good energy resolution. We have developped a calibration procedure for our total absorbing electromagnetic calorimeter which consists of 1022 lead fluoride (PbF_2) crystals. This procedure reconstructs the the single-module contributions to the events by solving a linear system of equations, involving the inversion of a 1022 x 1022-matrix. The system has shown its functionality at beam energies between 300 and 1500 MeV and represents a new and fast method to keep the calorimeter permanently in a well-calibrated state.
Measurement of Strange Quark Contributions to the Vector Form Factors of the Proton at Q**2=0.22 (GeV/c)**2
S. Baunack,K. Aulenbacher,D. Balaguer Ríos,L. Capozza,J. Diefenbach,B. Gl?ser,D. v. Harrach,Y. Imai,E. M. Kabu?,R. Kothe,J. H. Lee,H. Merkel,M. C. Mora Espí,U. Müller,E. Schilling,G. Stephan,C. Weinrich,J. Arvieux,M. A. El-Yakoubi,R. Kunne,F. E. Maas,M. Morlet,S. Ong,J. van de Wiele,S. Kowalski,Y. Prok,S. Taylor
Physics , 2009, DOI: 10.1103/PhysRevLett.102.151803
Abstract: A new measurement of the parity violating asymmetry in elastic electron scattering on hydrogen at backward angles and at a four momentum transfer of Q^2=0.22 (GeV/c)^2 is reported here. The measured asymmetry is A_LR=(-17.23 +- 0.82_stat +-0.89_syst) ppm. The Standard Model prediction assuming no strangeness is A_0=(-15.87 +- 1.22) ppm. In combination with previous results from measurements at forward angles, it it possible to disentangle for the first time the strange electric and magnetic form factors at this momentum transfer, G_E^s(0.22)=0.050 +- 0.038 +- 0.019 and G_M^s(0.22)=-0.14 +- 0.11 +- 0.11.
A New SPME Thermal Desorption Interface for HPLC  [PDF]
John Jairo Ríos Acevedo, Mohamed Nour Kayali Sayadi, Luis María Polo Díez
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2013, DOI: 10.4236/jasmi.2013.34028
Abstract:

A new SPME/HPLC interface is developed. It is based on thermal desorption from the SPME fiber and organic solvent collection of the desorbed analytes by sweeping them with an argon flow into a small organic solvent volume which is further injected into the HPLC chromatograph. Extraction and desorption parameters were investigated using five PAHs of different volatilities (naphthalene, acenaphthalene, fluorene, phenanthrene and anthracene) as test compounds and fluorimetric detection. Regression coefficients closed to 0.99 with RDS < 14% (n = 3) and detection limits in the range 0.07 - 0.99 μg.L-1 were found. A method was applied to determine the above PAHs in water samples. The results were compared with those supplied by the 550.1 EPA method showing the agreement of both methods at the 0.05 significance level.

La política de articulación entre la educación media y la superior: el caso de los programas de la secretaría de educación de bogotá*
Díaz Ríos,Claudia Milena;
Investigación y Desarrollo , 2012,
Abstract: this research is intended to understand the effects of the articulation policy between upper secondary and higher education in bogotá. the study approached several perspectives about the process of decision makers in the city education office, and those of the articulation coordinators in the higher education institutions and in the schools. in addition to that, the project developed three case studies in order to understand the implementation process and its effects on students. based on the findings, we determined that this policy was irrational and confused the problem of lack of identity of the upper secondary education with the scarce access to higher education. likewise, the articulation haspromoted different cooperative and conflictive interactions at schools, and a training of the students for the social experience in higher education. however, it has not achieved an increase in higher education opportunities for these students.
Trabajo, familia y desigualdad: la educación en las estrategias familiares frente a la crisis de la relación laboral
Díaz Ríos Claudia Milena
Revista Colombiana de Sociología , 2007,
Abstract: Esta ponencia constituye un informe de avance de la investigación "Trabajo, familia y desigualdad. La educación en las estrategias familiares frente a la crisis de la relación laboral", desarrollada en el marco de la beca Clacso-ASDI 2005. La investigación busca contribuir al estudio de la transmisión intergeneracional de la desigualdad a través del análisis de la relación entre trabajo, familia y escolaridad. En medio de las transformaciones del mercado de trabajo, y de los cambios demográficos y sociales que visibilizan configuraciones de familia diferentes de las construidas por los discursos de la segunda mitad del siglo XX, los hogares latinoamericanos se ven obligados a desarrollar estrategias para hacer frente a la crisis del empleo. Algunas de ellas, las menos, logran mejorar sus condiciones de vida; otras tantas apenas se adaptan a los cambios con grandes dificultades, con más o menos éxitos en el esfuerzo; por último, un número significativo y creciente de hogares a duras penas logra mantener su sobrevivencia comprometiendo el futuro de sus menores al no poder apoyar su proceso educativo. Este estudio se sustenta en la idea de que la fuerza de trabajo y el capital educativo de las familias son vitales para la inserción laboral pero que su valor es relativo a la estructura de oportunidades en la que están insertos. Para revisar esta idea, se recurre a las encuestas de hogares de Argentina, Brasil, Chile y México, a os 1990 y 2000, seleccionando a su vez a las familias urbanas con hijos adolescentes, por ser éstos los más vulnerables a ser la variable de ajuste de sus hogares. Junto con mostrar la dinámica de esta relación, se propone indagar acerca de las diferencias entre países a partir de sus características del mercado de trabajo, el perfil educativo de su población, así como las características de la estructura familiar.
La política de articulación entre la educación media y la superior. El caso de los programas de la Secretaría de Educación de Bogotá
Claudia Milena Díaz Ríos
Investigación y Desarrollo , 2012,
Abstract: Esta investigación tiene por objetivo entender los efectos de la política de Articulación entre la educación media y superior en Bogotá. Para ello, se reconstruyeron distintas perspectivas del proceso de funcionarios de la Secretaría de Educación y de coordinadores de Articulación de instituciones de educación superior y colegios oficiales, posteriormente se desarrollaron tres estudios de caso para identificar lo que sucede en la implementación del programa y los efectos en los estudiantes. Los hallazgos permiten argumentar que esta política no se constituyó de forma necesariamente racional, y confundió el problema de la educación media con el del acceso a la superior. Asimismo, el programa ha generado en las escuelas distintas acciones, tanto cooperativas como conflictivas, y una preparación de los estudiantes para la experiencia social de educación superior, pero no necesariamente un aumento del acceso a esta.
ética y aprendizaje en cirugía laparoscópica
Jara Rascón,J.; Subirá Ríos,D.;
Actas Urológicas Espa?olas , 2006, DOI: 10.4321/S0210-48062006000500011
Abstract: teaching operative skills are of paramount importance to urology training, specially in the period of time of the residency. because of that, the introduction of laparoscopy in our surgical activity must be followed by a careful planning of progressive training as an answer to this new need that would be well designed trying not to damage in whatever possible way to the patients operated with this new modality of surgical intervention. in this sense, each case and each indication of laparoscopy must be clarified individually, taking into account the basic principles of medical ethics (beneficency, no maleficency, justice and autonomy). so, it will be neccesary to decide about possible risks due to the experience of the surgeon or due to the modality of surgery. in this article, different options of training plannings in laparoscopy are mentioned taking as a reference the experience in laparoscopic prostatectomy, reasons of "prepared reconversion" are exposed and, finally, the authors explain the discussion about the subject and the extent of information offered to the patients looking for the best possibilities of decision making by the patients.
Phytotoxic effect of paper pulp sludge on Alfisol soil
Ríos,D; Pérez,C; Sandoval,M;
Journal of soil science and plant nutrition , 2012, DOI: 10.4067/S0718-95162012000200011
Abstract: the aim of this study was to evaluate the phytotoxicity of different doses of paper pulp sludge on alfisol soil in order to determine the potential use of the sludge as a soil improver. the organic waste was physically and chemically characterized to determine the presence of nutrients and heavy metals which is important for plant growth. the germination index (gi), the radicle length and the hypocotyl length of lactuca sativa l. and lolium perenne l. were evaluated for six doses of sludge/ soil: 10, 25, 50, 75, 100 and 150 t ha-1. a control without waste addition was also included. results indicated low concentration of heavy metals in the sludge which is reflected in the non-toxic effect on seed germination. gi in lactuca sativa l. reached a maximum in the control with 155%; however, there were no significant differences among the treatments. gi in lolium perenne l. had the highest value at a dose of 50 t ha-1 with 143%, indicating significant differences between the treatments. the use of paper pulp sludge as a soil improver could be beneficial given the nutrient concentration, the low concentration of heavy metals and the no toxic effect depending on the species treated.
Introducción a la teoría geométrica de grupos
SALAZAR-DíAZ,OLGA; VERGARA-RíOS,GRABIEL;
Revista Integración , 2011,
Abstract: abstract. in this article we will give an introduction to geometric group theory. we will see how from a finite presentation of a group, we can give this group a metric space structure. we discuss the action of the group on this space and we study geometric properties preserved under quasiisometry.
Tiempo Mínimo-Conocimiento Suficiente: La Cuasi-Etnografía Sociotécnica en Psicología Social
Silva Ríos,Carlos; Burgos Dávila,César;
Psicoperspectivas , 2011, DOI: 10.5027/psicoperspectivas-Vol10-Issue2-fulltext-146
Abstract: in social psychology as well as in various social sciences, ethnographic practice is characterized by the researcher?s participation in the daily lives of people over a long period. inherited from the anthropological tradition, the criterion of prolonged stay to do fieldwork has been dominant. we take distance from this requirement and propose that it is possible to generate sufficient knowledge in minimum time. our starting point is both quasi-ethnography and our practice as researchers. we assume actor-network theory and thick description as a bridge to a plausible theoretical and methodological knowledge production within a minimum time.
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