2,027 research outputs found
Exact monopole instantons and cosmological solutions in string theory from abelian dimensional reduction
We compute the exact string vacuum backgrounds corresponding to the
non-compact coset theory . The conformal field theory defined by
the level results in a five dimensional singular solution that
factorizes in an asymptotic region as the linear dilaton solution and a
model. It presents two abelian compact isometries that allow to reinterpreting
it from a four dimensional point of view as a stationary and magnetically
charged space-time resembling in some aspects the Kerr-Newman solution of
general relativity. The theory on the other hand describes a
cosmological solution that interpolates between a singular phase at short times
and a universe after some planckian times.Comment: 18 pages, section 5 replaced by 5 and 6, references added; to appear
in Phys. Rev.
La obturación de valles por procesos de ladera: el origen de La Vega de Metztitlan (México)
[Resumen] En las estribaciones de la Sierra Madre Oriental (México) se localiza el lago de Metztitlán y la vega del mismo nombre. Su origen se debe a la obturación del valle por un importante deslizamiento y posteriormente un desprendimiento. En este trabajo se exponen los primeros resultados del estudio geomorfológico, se aporta una cartografía de detalle y se propone una primera explicación de la evolución del área.[Abstract] The lake and valley of Metztilán is located in Sierra Madre Oriental range (Mexico). Its origin is due to the slope collapse after great rockslide. This paper exposes the firsts geomorphologic analysis of the feature, and includes and detailed geomorphologic map. A different evolution phases is determined
Estudio descriptivo del programa de rehabilitación cardiaca de la Clínica Las Américas
Estudio descriptivo de antes y después que demuestra la eficacia y seguridad del Programa de Rehabilitación Cardiaca de la Clínica Las Américas, con base en un seguimiento a 77 pacientes, en el que se evidenció mejoría de la capacidad funcional así como disminución del perímetro abdominal y de las cifras basales de presión arterial sistólica y diastólica sin complicaciones severas, en todos los tipos de paciente, independientemente de la fracción de eyección o las variables demográficas. De igual forma, se describen las características epidemiológicas de la población y de los factores de riesgo cardio-cerebro-vascular.A before and after descriptive study that shows the efficacy and safety of the Cardiac Rehabilitation Program of the Clínica Las Americas, based on the follow-up of 77 patients in which we evidenced improvement in functional capacity as well as a decrease of abdominal girth and baseline values of systolic and diastolic blood pressure without severe complications in all type of patients, regardless of ejection fraction or demographic variables. Likewise, we describe the epidemiological characteristics of the population and the cardio-cerebro-vascular risk factors
Quantification of Lansoprazole in Oral Suspension by Ultra-High-Performance Liquid Chromatography Hybrid Ion-Trap Time-of-Flight Mass Spectrometry
An LC-MS/MS method was developed and validated to be used as a stability indicating assay for the study of a 3 mg/mL lansoprazole oral suspension. The method utilizes a UPLC (ultra-performance liquid chromatography) column and unique mass spectrometric detection (ion-trap time-of-flight (IT-TOF)) to achieve a sensitive (LOD 2 ng/mL), accurate, and reproducible quantification of lansoprazole. This method reports an intraday and interday coefficient of variation of 2.98 ± 2.17% (n = 5 for each concentration for each day) and 3.07 ± 0.89% (n = 20 for each concentration), respectively. Calibration curves (5–25 μg/mL) were found to be linear with an R2 value ranging from 0.9972 to 0.9991 on 4 different days. Accuracy of the assay, expressed as % error, ranged from 0.30 to 5.22%. This method is useful for monitoring the stability of lansoprazole in oral suspension
Administración y planeación general de la formación profesional
El texto presenta un esquema completo de toda la metodología que se utilizaba para programar la formación profesional en el SENA, con el propósito de dar los elementos, herramientas e ideas generales y específicas que permitieran lograr con éxito la labor del Instructor.The text presents a complete outline of all the methodology that was used to program vocational training at SENA, with the purpose of giving the general and specific elements, tools and ideas that would allow the Instructor's work to be successfully achieved.Introducción -- Objetivo general -- Administración de la Formación Profesional -- Planeación general de la Formación Profesional -- Etapa de planeación -- Etapa de programación -- Etapa de evaluaciónnaDocumento sin fecha, se aproxima fecha a la década39 página
Marrying research evidence and policies in Latin America and the Caribbean: The Case of Violence
Violence is probably the most important public health problem in Latin America and the Caribbean. Despite the efforts to attach that problem, research and policies do not feedback each other in an apropiate way. There is need for develop implementation research in the region in order to reduce that gap.Fil: Ardila Gómez, Sara Elena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Lanus. Departamento de Salud Comunitaria; Argentina. Universidad de Buenos Aires. Facultad de Psicología. Área de Salud Pública y Salud Mental; ArgentinaFil: Lugo Palacios, D.. London School Of Hygiene And Tropical Medicine; Reino UnidoFil: Vargas Palacios, E.. No especifíca
Feasibility study to characterize the production of antineutrons in high energy collisions through charge exchange interactions
Simulations to evaluate the feasibility of identification and
kinematic characterization via the hadronic charge exchange (CEX) interaction
are reported. The target neutrons are those
composing the silicon nuclei of which inner tracking devices present in LHC
experiments are made. Simulations of collisions in PYTHIA were carried out
at different energies to investigate production and the expected
energy spectra. Then, two types of GEANT4 simulations were performed,
placing an point source at the ALICE primary vertex as a working
example. In the first simulation, the was kept at an arbitrary (1 GeV)
fix value to develop an identification and kinematics reconstruction
protocol. The second GEANT4 simulation used the resulting PYTHIA at
TeV energy spectra. In both simulations, the
occurrence of CEX interactions was identified by the unique outgoing .
The simplified simulation allowed to estimate a 0.11% CEX-interaction
identification efficiency at GeV. The CEX-partner identification
is challenging because of the presence of silicon nucleus-fragmentation
protons. Momentum correlations between the and all possible
pairs showed that CEX-partner identification and
kinematics reconstruction corresponds to minimal momentum-loss events. The use
of ITS information is found to improve identification and
kinematic characterization in both simulations. The final protocol applied to
the realistic simulation resulted in a identification and kinematic
reconstruction efficiency of 0.006%, based solely on pair
observable. Thus, the expected rate of identified and kinematically
reconstructed should lie in the order of 100,000 per second,
illustrating the feasibility of the method.Comment: 6 pages, 11 figure
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