1,601 research outputs found
Estimation of the distribution of random shifts deformation
Consider discrete values of functions shifted by unobserved translation
effects, which are independent realizations of a random variable with unknown
distribution , modeling the variability in the response of each
individual. Our aim is to construct a nonparametric estimator of the density of
these random translation deformations using semiparametric preliminary
estimates of the shifts. Building on results of Dalalyan et al. (2006),
semiparametric estimators are obtained in our discrete framework and their
performance studied. From these estimates we construct a nonparametric
estimator of the target density. Both rates of convergence and an algorithm to
construct the estimator are provided
Full particle orbit effects in regular and stochastic magnetic fields
We present a numerical study of charged particle motion in a time-independent
magnetic field in cylindrical geometry. The magnetic field model consists of an
unperturbed reversed-shear helical part and a perturbation consisting of a
superposition of modes. Contrary to most of the previous studies, the particle
trajectories are computed by directly solving the full Lorentz force equations
of motion in a six-dimensional phase space using a sixth-order, implicit,
symplectic Gauss-Legendre method. The level of stochasticity in the particle
orbits is diagnosed using averaged, effective Poincare sections. It is shown
that when only one mode is present the particle orbits can be stochastic even
though the magnetic field line orbits are not stochastic. The lack of
integrability of the particle orbits in this case is related to separatrix
crossing and the breakdown of the global conservation of the magnetic moment.
Some perturbation consisting of two modes creates resonance overlapping,
leading to Hamiltonian chaos in magnetic field lines. Then, the particle orbits
exhibit a nontrivial dynamics depending on their energy and pitch angle. It is
shown that the regions where the particle motion is stochastic decrease as the
energy increases. The non-monotonicity of the -profile implies the existence
of magnetic ITBs which correspond to shearless flux surfaces located in the
vicinity of the -profile minimum. It is shown that depending on the energy,
these magnetic ITBs might or might not confine particles. That is, magnetic
ITBs act as an energy-dependent particle confinement filter. Magnetic field
lines in reversed-shear configurations exhibit topological bifurcations due to
separatrix reconnection. We show that a similar but more complex scenario
appears in the case of particle orbits that depends in a non-trivial way on the
energy and pitch angle of the particles.Comment: 25 pages, accepted for publication in Phys. Plasma
Análisis de las condiciones de seguridad vial ligadas a temas de infraestructura en las vías rápidas de Bogotá
Trabajo de investigaciónRevisión del paquete “salve vidas” diseñado por la Organización mundial de la salud (OMS), en la infraestructura vial de Bogotá, con el fin de disminuir el nivel de mortalidad debido a la accidentalidad vial, por medio de la comparación de países que han realizado proyectos para mitigar la accidentalidad vial y que hacen uso de las recomendaciones de la OMS, con el estado actual de las zonas con mayor índice de mortalidad vial de Bogotá.INTRODUCCIÓN.
1. ANTECEDENTES Y JUSTIFICACIÓN.
2. PLANTEAMIENTO Y FORMULACIÓN DEL PROBLEMA.
3. MARCO DE REFERENCIA
4. OBJETIVOS
5. ALCANCES Y LIMITACIONES.
6. METODOLOGÍA.
7. ANTECEDENTES INTERNACIONALES
8. ANÁLISIS DE LA SEGURIDAD VIAL DE BOGOTÁ
9. FACTORES A ESTUDIAR DE INFLUENCIA EN LA ACCIDENTABILIDAD VIAL EN BOGOTÁ
10. POSIBLES CAUSAS DE ACCIDENTALIDAD.
11. ESTUDIO DE LAS ZONAS ROJAS DE BOGOTÁ 12. COMPARACIÓN DE BOGOTÁ CON PAÍSES QUE CUMPLEN CON LAS
NORMATIVAS DICTADAS POR LA OMS
13. RESUMEN DE LA COMPARACIÓN CON LOS OTROS PAÍSES.
14. CONCLUSIONES
15. RECOMENDACIONES
BIBLIOGRAFÍAPregradoIngeniero Civi
The influence of fractional diffusion in Fisher-KPP equations
We study the Fisher-KPP equation where the Laplacian is replaced by the
generator of a Feller semigroup with power decaying kernel, an important
example being the fractional Laplacian. In contrast with the case of the stan-
dard Laplacian where the stable state invades the unstable one at constant
speed, we prove that with fractional diffusion, generated for instance by a
stable L\'evy process, the front position is exponential in time. Our results
provide a mathe- matically rigorous justification of numerous heuristics about
this model
Uso de las TIC para mejorar el aprendizaje del área de matemática de los estudiantes de cuarto grado primaria, Ascope
El presente estudio tiene como propósito demostrar en qué medida el uso de las tic
mejora el aprendizaje del área de matemática de los estudiantes de cuarto grado
de una institución educativa del nivel primario del distrito de Ascope, 2022.
Este fue de tipo experimental, con un diseño cuasi experimental. La población
estuvo compuesta por los estudiantes del nivel primario de una institución educativa
del distrito de Ascope, de la cual se tomó una muestra de 94 alumnos (47 grupo
experimental y 47 grupo control). El instrumento empleado fue un test, compuesto
por 8 items, los resultados fueron procesados a través de los softwares Microsoft
Excel y SPSS.
Los resultados obtenidos muestran una gran diferencia entre los resultados en el
grupo experimental, mientras que en el pre test se obtuvo el 53% en el nivel de
logrado, en el post test se llegó a un 100% de logrado. En el grupo control no se
obtuvo mucha diferencia el pre test tuvo un 62% de logrado y el post test un 81%,
teniendo tan solo una mejora del 19%. Concluyendo que el uso de las tic en las
matemáticas mejoran el aprendizaje de los estudiantes
Diseño de un programa de seguridad y salud en el trabajo para la Sunafil
Universidad Nacional Agraria La Molina. Facultad de Economía y Planificación. Departamento Académico de Gestión EmpresarialEl presente trabajo tiene por objetivo evaluar las condiciones laborales del personal para proponer acciones de mejora. Por ello se elaboraron Matrices IPER por puesto de trabajo y Mapas de Riesgo con la finalidad de determinar los controles necesarios para prevenir daños a la persona (daño en términos de lesión o enfermedad en el trabajo) y sean implementados a corto plazo por La Sunafil. El método utilizado en este trabajo fue Descriptivo, porque se realizaron entrevistas, inspecciones y se observaron los procesos relacionados con la seguridad y salud, además se identificó de que el tema ha sido poco reconocido siendo necesario explorar e indagar; de diseño No Experimental, observando fenómenos tal y como se dieron en su contexto natural para después analizarlos. El creciente desarrollo de la industria a nivel mundial, ha hecho necesario incrementar los niveles de seguridad en los lugares de trabajo. Incrementar la seguridad en los procesos, puestos de trabajo, en la salud de los trabajadores, etc. los empleadores están obligados a exhibir su Programa de Seguridad y Salud en el Trabajo de acuerdo al D.S. N° 005-2012- TR ¨Reglamento de Seguridad y Salud en el Trabajo¨, donde establece las actividades para controlar factores de riesgos, accidentes laborales, enfermedades ocupacionales entre otros.Trabajo de suficiencia profesiona
One Camera in Hand for Kinematic Calibration of a Parallel Robot
The main purpose of robot calibration is the correction of the possible errors in the robot parameters. This paper presents a method for a kinematic calibration of a parallel robot that is equipped with one camera in hand. In order to preserve the mechanical configuration of the robot, the camera is utilized to acquire incremental positions of the end effector from a spherical object that is fixed in the word reference frame. Incremental positions of the end effector are related to incremental positions of encoders of the motors of the robot. A kinematic model of the robot is modified in order to take into account possible errors of kinematic parameters. The solution of the model utilizes incremental positions of the resolvers and end effector, the new parameters minimizes errors in the kinematic equations. Spherical properties and intrinsic camera parameters are utilized to model sphere projection in order to improve spatial measurements. The robot system is designed to carry out tracking tasks and the calibration of the system is finally validated by means of integrating the errors of the visual controller
Unusual Micrometric Calcite-Aragonite Interface in the Abalone Shell Haliotis (Mollusca, Gastropoda)
Species of Haliotis (abalone) show high variety in structure and mineralogy of the shell. One of the European species (Haliotis tuberculata) in particular has an unusual shell structure in which calcite and aragonite coexist at a microscale with small patches of aragonite embedded in larger calcitic zones. A detailed examination of the boundary between calcite and aragonite using analytical microscopies shows that the organic contents of calcite and aragonite differ. Moreover, changes in the chemical composition of the two minerals seem to be gradual and define a micrometric zone of transition between the two main layers. A similar transition zone has been observed between the layers in more classical and regularly structured mollusk shells. The imbrication of microscopic patches of aragonite within a calcitic zone suggests the occurrence of very fast physiological changes in these tax
Biological activities of 13, 28-epoxyoleanane triterpene saponins from two peruvian Myrsinaceae
Two known 13,28-epoxy-oleanane triterpene saponins (1) and (2), were isolated from the 95% ethanolic extract of the roots of Myrsine coriaceae and Myrsine andina. Their structures were deduced by combined spectral analysis and chemical evidences based on data reported in the literature. Compounds 1 and 2 were evaluated in vitro against different cellular models such as Mycobacterium tuberculosis, Leishmania amazonensis axenic amastigotes, six human cancer cell lines (Hs683, T98G, U251, HT29, MCF7, SKMEL28) and two murine cell lines (CT26 and B16F10). Compound 1 was found to exhibit antileishmanial activity (IC50 = 16 µg/mL) whereas compound 2 was inactive (IC50 > 50 µg/mL). Furthermore, compound 1 exhibited stronger inhibition activity on human cancer cells (IC50 = 15 µg/mL) and on murine cell lines (IC50 = 10 µg/mL) than compound 2 (IC50 > 82 and 42 µg/mL, respectively). As the only difference between 1 and 2 is due to a substitution of an aldehyde group by a hydroxymethyl moiety, these results showed the crucial role of the aldehyde function at C-30 for the cytotoxicity. In contrast, none of the tested compounds revealed activity against M. tuberculosis
A socio-interpersonal perspective on the disclosure of childhood adversity: A qualitative comparative approach in Irish survivors
Childhood adversity (i.e., sexual, physical, or emotional abuse, and physical or emotional neglect) is a widespread, but often underreported, issue. While disclosure can be important for recovery, findings are inconsistent and often lack consideration of wider social and interpersonal contexts. This study aimed to examine disclosure in survivors of childhood adversity by applying a socio-interpersonal perspective. It further aimed to explore cultural and contextual influences on disclosure by assessing survivors from two distinct adversity contexts. Semi-structured interviews were conducted with 12 Irish survivors from an intrafamilial adversity context (mean age: 57.4 years, 11 females) and 17 Irish survivors from an institutional adversity context (mean age: 60.7 years, 10 females). Data was analyzed using framework analysis and the application of the socio-interpersonal model. Findings indicate unsuccessful and non-disclosure in childhood, with increased disclosure in adulthood. Themes identified shared disclosure-related factors (e.g., shame, inaction, lack of infrastructural and social support, societal acknowledgement); as well as context-specific findings (e.g., engrained family secret in the intrafamilial sample, power and influence of the church in the institutional sample). Results emphasize the necessity of considering not only the child-perpetrator relationship, but also the complex social, cultural, and interpersonal contexts within which the individual is embedded
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