Evidence for Renewal and Reconstitution of Marginal Zone Macrophages in Young and Aged Mice

Aging in humans and mice correlates with decline in immune health, affecting both innate and adaptive immunity. Response against blood-borne bacterial pathogens is compromised because of the deterioration of the marginal zones of the spleen and decrease in frequency of marginal zone macrophages (MZM). This thesis asked if low cell turnover is the cause for the decrease of MZM, using cell proliferation to indicate cell turnover in spleens of mice. First, evidence showed MZM proliferation occurred in spleens of young mice and was decreased in the MZM from aged mice. Second, transfer of young bone marrow into old mice replenished some of the lost MZM. The experimental design used histological sections and flow cytometry to detect MZM that had proliferated. These results may explain the reason for deteriorated marginal zones, as well as a potential therapeutic to reestablish MZM and promote protective immune response to bacteria in the aged

Inner and outer edge states in graphene rings: A numerical investigation

We numerically investigate quantum rings in graphene and find that their electronic properties may be strongly influenced by the geometry, the edge symmetries and the structure of the corners. Energy spectra are calculated for different geometries (triangular, hexagonal and rhombus-shaped graphene rings) and edge terminations (zigzag, armchair, as well as the disordered edge of a round geometry). The states localized at the inner edges of the graphene rings describe different evolution as a function of magnetic field when compared to those localized at the outer edges. We show that these different evolutions are the reason for the formation of sub-bands of edge states energy levels, separated by gaps (anticrossings). It is evident from mapping the charge densities that the anticrossings occur due to the coupling between inner and outer edge states.Comment: 8 pages, 7 figures. Figures in low resolution due to size requirements - higher quality figures on reques

Resonant tunneling through protected quantum dots at phosphorene edges

We theoretically investigate phosphorene zigzag nanorribons as a platform for constriction engineering. In the presence of a constriction at the upper edge, quantum confinement of edge protected states reveals resonant tunnelling Breit-Wigner transmission peaks, if the upper edge is uncoupled to the lower edge. Coupling between edges in thin constrictions gives rise to Fano-like and anti-resonances in the transmission spectrum of the system.Comment: 8 pages,7 figure

Escuelas gestora de ambientes de paz

95 p. Recurso Electr?nicoEn la instituci?n escolar convergen todos los problemas sociales como la violencia, reflejada en las conductas agresivas de los estudiantes. Este fen?meno es el resultado de m?ltiples factores entre los que se encuentra la familia, como primera sociedad en la que se empiezan a formar los hombres del presente y del ma?ana. La Instituci?n Educativa Maximiliano Neira Lamus de la ciudad de Ibagu? presenta un alto nivel de agresividad e intolerancia reflejada en los golpes y maltrato verbal, raz?n por la cual hemos querido ahondar en los factores familiares que est?n incidiendo directamente en este tipo de comportamientos desde la perspectiva de Enrique Chaux. Seg?n Chaux las principales causas de la violencia escolar se encuentran en la familia y es generada por tres factores: El maltrato infantil, el abandono y la permisividad exagerada. A partir de estos fundamentos construimos una tabla de indicadores que nos permitiera identificar y corroborar estos tres elementos de la poblaci?n en estudio.In school institutions many of the social problems are related to violence which is reflected in the aggressive conducts of the students. This phenomenon is a result of multiple factors but the major factor is the upbringing of the child. These children are the men and women of today and tomorrow in the first world society. The educative institution Maximiliano Neira Lamus located in the city of Ibague presents a high level of aggression and tolerance win the form of verbal abuse. For this reason we wanted to dig deeper and study the factors that are directly affecting this type of behavior through the perspective of Enrique Chaux. According to Chaux the main cause of school violence is found in the behaviors of the family and there are three factors that are noted: child abuse, neglect, and permissiveness. Based on these factors, we constructed a table of indicators that allows us to identify these three elements in the studied population. Key works: Coexistence, Abuse, Aggression, Abandonment, PermissivenessEspecializaci?n en Gerencia de Instituciones Educativa

Graphene kirigami as a platform for stretchable and tunable quantum dot arrays

The quantum transport properties of a graphene kirigami similar to those studied in recent experiments are calculated in the regime of elastic, reversible deformations. Our results show that, at low electronic densities, the conductance profile of such structures replicates that of a system of coupled quantum dots, characterized by a sequence of minibands and stop-gaps. The conductance and I-V curves have different characteristics in the distinct stages of elastic deformation that characterize the elongation of these structures. Notably, the effective coupling between localized states is strongly reduced in the small elongation stage, whereas in the large elongation regime the development of strong, localized pseudomagnetic field barriers can reinforce the coupling and reestablish resonant tunneling across the kirigami. This provides an interesting example of interplay between geometry and pseudomagnetic field-induced confinement. The alternating miniband and stop-gaps in the transmission lead to I-V characteristics with negative differential conductance in well defined energy/doping ranges. These effects should be stable in a realistic scenario that includes edge roughness and Coulomb interactions, as these are expected to further promote localization of states at low energies in narrow segments of graphene nanostructures.Comment: 10 pages, 10 figure

Quantized transport, strain-induced perfectly conducting modes and valley filtering on shape-optimized graphene Corbino devices

The extreme mechanical resilience of graphene and the peculiar coupling it hosts between lattice and electronic degrees of freedom have spawned a strong impetus towards strain-engineered graphene where, on the one hand, strain augments the richness of its phenomenology and makes possible new concepts for electronic devices and, on the other hand, new and extreme physics might take place. Here, we demonstrate that the shape of substrates supporting graphene sheets can be optimized for approachable experiments where strain-induced pseudomagnetic fields (PMF) can be tailored by pressure for directionally selective electronic transmission and pinching-off of current flow down to the quantum channel limit. The Corbino-type layout explored here furthermore allows filtering of charge carriers according to valley and current direction, which can be used to inject or collect valley-polarized currents, thus realizing one of the basic elements required for valleytronics. Our results are based on a framework developed to realistically determine the combination of strain, external parameters, and geometry optimally compatible with the target spatial profile of a desired physical property --- the PMF in this case. Characteristic conductance profiles are analyzed through quantum transport calculations on large graphene devices having the optimal shape.Comment: 5+7 figures. Supporting information include

Composici?n corporal y condici?n f?sica en los estudiantes de educaci?n b?sica secundaria y media de la Instituci?n Educativa San Antonio del municipio de Cunday Tolima

140 p. Recurso Electr?nicoIntroducci?n: La composici?n corporal y otros componentes de la condici?n f?sica han demostrado ser importantes indicadores de salud. Es por ello que se plantea el siguiente objetivo: Analizar los niveles de composici?n corporal y condici?n f?sica en los estudiantes de educaci?n b?sica secundaria y media de la instituci?n educativa San Antonio del municipio de Cunday-Tolima. Adem?s fueron utilizados los siguientes materiales y m?todos: participaron 323 estudiantes con una muestra de 165 (hombres: 82 y mujeres: 83), con un rango de edad de 11 a 18 a?os. Se aplicaron las pruebas f?sicas de la bater?a Alpha Fitness Test, versi?n extendida. Se evalu? ?ndice de masa corporal (IMC), Per?metro de Cintura y Porcentaje de Grasa. Dando como Resultados: Se encontraron diferencias de g?nero en las variables estudiadas, con mayor IMC y porcentaje graso en los ni?os y adolescentes (20,9 kg/m2 vs. 19,6kg/ m2 y 12,9 % vs 23 %, respectivamente); tambi?n, el per?metro de cintura fue mayor en los hombres (64,8 cm vs. 62,5 cm), ellos presentaron niveles m?s elevados de masa corporal, porcentaje de grasa y per?metro de cintura, con diferencias significativas (p<0.05). Adem?s alcanzaron niveles m?s elevados para la capacidad aer?bica, el salto con pies juntos y la velocidad, con diferencias estad?sticamente significativas en el VO2m?x y el salto (p<0.05). Se hallaron correlaciones medias y considerables entre algunas variables estudiadas. Lo que permiti? llegar a las siguientes conclusiones: El 73,3% (n1=121) de los estudiantes poseen peso normal, seguido por el 25,5% (n2=42) con riesgo de sobrepeso por ?ltimo, s?lo el 1,2% (n3=2) de los escolares tienen sobrepeso. Los hombres muestran mejores niveles de capacidad aer?bica, capacidad musculo-esquel?tica y capacidad motora. Palabras Claves: Composici?n Corporal, Capacidades F?sicas Condicionales, Instituci?n Educativa.Introduction: The body insertion and other components of the physical condition are important witnesses of health. That is why the following objective is posed: To analyze the levels of body composition and physical condition in the secondary and middle school students of the San Antonio educational institution in the municipality of Cunday-Tolima. In addition, the following materials and methods were used: 323 students participated with a sample of 165 (men: 82 and women: 83), with an age range of 11 to 18 years. The physical tests of the Alpha Fitness Test battery, extended version, were applied. Body mass index (BMI), waist circumference and percentage of fat were evaluated. Giving as Results: Gender differences were found in the variables studied, with higher BMI and fat percentage in children and adolescents (20.9 kg / m2 vs. 19.6 kg / m2 and 12.9% vs 23%, respectively); also, the waist circumference was higher in men (64.8 cm vs. 62.5 cm), they presented higher levels of body mass, fat percentage and waist circumference, with significant differences (p<0.05). They also reached higher levels for aerobic capacity, jumping with feet together and speed, with statistically significant differences in VO2max and jump (p<0.05). Mean and considerable correlations were found between some variables studied. What allowed to reach the following conclusions: 73.3% (n1 = 121) of the students possess but normal, followed by 25.5% (n2 = 42) with risk of overweight last, only 1.2% (n3 = 2) of Schoolchildren are overweight. Men show better levels of aerobic capacity, musculoskeletal capacity and motor ability. Keywords: Corporal Composition, Physical Conditional Capacities, Educational Institution