ABSTRACT Blazars are the most active extragalactic gamma-ray sources. They show sporadic bursts of activity, lasting from hours to months. In this work we present a 10-year analysis of a sample of bright sources detected by Fermi-LAT (100 MeV 300 GeV). Using 2-week binned light curves (LC) we estimate the duty cycle (DC): fraction of time that the source spends in an active state. The objects show different DC values, with an average of 22.74% and 23.08% when considering (or not) the extragalactic background light ( EBL). Additionally, we study the so-called “blazar sequence” trend for the sample of selected blazars in the ten years of data. This analysis constrains a possible counterpart of sub-PeV neutrino emission during the quiescent states, leaving open the possibility to explain the observed IceCube signal during the flaring states.

RESUMEN Los blazares son las fuentes de rayos gamma más activas. Presentan períodos esporádicos de actividad, con duraciones de horas a meses. En este trabajo presentamos un análisis de una muestra de fuentes brillantes detectadas por Fermi-LAT (100 MeV - 300 GeV) durante una década. Usando curvas de luz con episodios de 2 semanas estimamos el ciclo de actividad (DC): la fracción de tiempo que la fuente pasa en el estado activo. Los objetos presentan diferentes valores del DC, con promedios de 22.74% y 23.08% cuando se considera y no se considera el fondo de luz difusa. Adicionalmente, estudiamos la tendencia conocida como “secuencia de blazares”. Este análisis restringe una posible contraparte de neutrinos con energías de sub-PeV durante los estados estacionarios, dejando la posibilidad de explicar las observaciones de IceCube durante los períodos de fase activa.

Abstract Seeds Trompillo (Encyclia adenocaula (La Llave & Lex.) Schltr. Orchidaceae) from mature capsules of a population, were analyzed for: size, structure, weight, number of seeds per gram and viability by tetrazolium test with without pretreatment of Ca(OCl)2 and Tween, asymbiotic test germination conditions in vitro to compare the viability of them. Germination was evaluated in germination percentage and days in three semi-solid culture media (MS + CV; MS + banana extract; MS + coconut water). The seed size was 0.56±0.08 mm long by 0.09±0.01mm wide, covering an area of 3.25±0.5 mm2, with an approximate weight of 1.6±0.08μg, registering 63 500 seeds per gram. The percentage of viability by tetrazolium test showed statistically significant differences (p≤0.05) between treatments, excelling treatments Tetrazolium 1 % with and without Tween with 50.3 and 48.2% respectively, pretreatment with Ca(OCl)2 affected directly the viability of the seeds. In asymbiotic germination were significant statistical differences (p≤ 0.05) between treatments, highlighting MS + CV with 56.9% germination at 30 days, followed by medium MS + coconut water with 31.4% germination to 55.7 days, finally medium MS + banana extract with 23% to 59.1 days.

Resumen Semillas de Trompillo (Encyclia adenocaula (La Llave & Lex.) Schltr. Orchidaceae), procedentes de cápsulas maduras de una población, fueron analizadas respecto a: tamaño, estructura, peso, número de semillas por gramo y la viabilidad mediante prueba de Tetrazolio con y sin pretratamiento de Ca(OCl)2 y Twenn , la prueba de germinación asimbiótica en condiciones in vitro para comparar la viabilidad de las mismas. La germinación, se evaluó en porcentaje y días a germinación en tres medios semisólidos de cultivo (MS+CV; MS+extracto de plátano; MS + agua de coco). El tamaño de la semilla fue de 0.56±0.08 mm de largo por 0.09±0.01mm de ancho, cubriendo un área de 3.25±0.5 mm2, con un peso aproximado de 1.6±0.08(μg, registrando 63 500 semillas por gramo. El porcentaje de viabilidad mediante la prueba de Tetrazolio presentó diferencias estadísticas significativas (p≤ 0.05) entre los tratamientos, sobresaliendo los tratamientos de Tetrazolio al 1% con y sin Twenn con 50.3 y 48.2% respectivamente, el pretratamiento con Ca(OCl)2 afectó directamente la viabilidad de las semillas. En la germinación asimbiótica se presentaron diferencias estadísticas significativas (p≤ 0.05) entre los tratamientos, destacando MS + CV con 56.9% de germinación a los 30 días, seguidos de medio MS + agua de coco con 31.4% de germinación a los 55.7 días, por último el medio MS + extracto de plátano con 23% a los 59.1 días.

In the process of learning there are several important events and activities involved. Some actions such as discussion, exposition of ideas and the development of projects or the possible solution of different shown problems can be complemented with the use of common technologies, experimental facts and visual didactic materials. We consider that the discussion of different propositions or techniques that solve some specific tasks contributes to the interaction between students and, in the case of computer algorithms, enable them to build their own experimental tools. Different situations, questions, results or predictions can be proposed and discussed during and after the construction of a computer program that shows in real time an animated visual 3D view of the numeric solution. We present deduction of Verlet's algorithms and apply them to some particular mechanical systems begining with free particle, and adding in each time some physical considerations that involves more complexity in the problem.

En el proceso de aprendizaje están involucrados varios hechos y actividades importantes. Algunas acciones como la discusión, la exposición de ideas y el desarrollo de proyectos, así como la posible solución de diferentes problemas planteados pueden ser complementadas con el uso de tecnologías comunes, hechos experimentales y materiales visuales didácticos. Consideramos que la discusión de diferentes proposiciones o técnicas para resolver una tarea específica contribuye a la interacción entre los estudiantes y, en el caso de los algoritmos de cómputo, los capacita para construir sus propias herramientas experimentales. Diferentes situaciones, preguntas, resultados o predicciones pueden ser propuestos y discutidos durante y después de la construcción de un programa de cómputo que presenta, en tiempo real, una visión animada tridimensional de la solución numérica. En este trabajo presentamos una deducción de los algoritmos de Verlet y los aplicamos a algunos sistemas mecánicos particulares, comenzando con la partícula libre y agregando, cada vez, algunas consideraciones físicas que incorporan, de manera gradual, complejidad al problema.

We provide evidence of the presence of 18 additional bird species to the avifauna of the state of Hidalgo (including an alien species). We also provide information of 14 outstanding or recent records of species previously recorded in the state. To date, the confirmed presence of 496 native bird species constitutes the species richness of Hidalgo, in addition to 6 introduced alien species.

The purpose of this research was to demonstrate the dependant relationship between the Argentine ant Linepithema humile Mayr, plant coverage, and human settlements. A method was designed in order to sample the presence of the Argentine ant and other ant species that may had influenced L. humile distribution, under different types of vegetation and percentages of plant coverage, taking in consideration the distance from human settlements. Eight sample stations were established. Four of these stations were found on a dwelling home and the other four were found on similar areas, but far from human settlements. Three transects were established from the center of each sampling station (Tt1, shrublike vegetation, Tt2, herblike vegetation and Tt3, no vegetation). Transects were compound by 10 m side quadrants. A negative correlation was found between nest number of L. humile and human settlement distance, therefore nests were not found at distances higher than 80 m, in all studied areas. There was a positive and significant correlation between nest number of L. humile and plant coverage percentage, regardless the type of vegetation found. The same trend was found for other ant species studied in the area. Finally, it was proved that the distribution of L. humile nests is not influenced by other ant species.

Recently, nanotechnology has developed to a stage that makes it possible to process magnetic nanoparticles for the site-specific delivery of drugs. To this end, it has been proposed as biomaterial for drug delivery system in which the drug release rates would be activated by a magnetic external stimuli. Alginate has been used extensively in the food, pharmaceutical and biomedical industries for their gel forming properties in the presence of multivalent cations. In this study, we produced iron oxide nanoparticles by coprecipitation of Fe(III) and Fe(II). The nanoparticles were entrapped in Ca alginate beads before and after alginate gelation. XRD analysis showed that particles should be associated to magnetite or maghemite with crystal size of 9.5 and 4.3 nm, respectively. Studies using Mössbauer spectroscopy corroborate the superparamagnetic behavior. The combination of magnetic properties and the biocompatibility of alginate suggest that this biomaterial may be used as biomimetic system.

Antimicrobial chemotherapy in human and veterinary medicine is one of the most important therapeutic tool against pathogenic agents causing infectious diseases; nevertheless, the development of multiple resistant strains during the last years has been reported. Some of the measures adopted to control this problem have been the veterinary prescription of antimicrobials for animal use, the permanent rotation of drugs, and the implementation of continuous monitoring programs for bacterial resistance. In the present paper the sensitivity of pathogenic bacteria isolated from dairy cows suffering mastitis in different regions of Chile against antimicrobials most frequently used in dairy herds is reported. The Plate Dilution Method and the Minimum Inhibitory Concentration (MIC) were used to evaluate the bacterial resistance of each isolated strain. A total of 449 bacterial strains were isolated from 963 aseptically collected milk samples in the 5th and Metropolitan Regions of Chile, E. coli being the most frequent mastitis pathogen recovered. In the 10th Region, however, S. aureus was the main pathogen among 1012 bacterial strains isolated from 2000 milk samples. S. aureus, Streptococcus spp and coagulase-negative Staphilococcus (CNS) were shown to be highly resistant to amoxicilin, ampicillin, penicillin, streptomycin and lincomicyn. Resistance to cloxacilin of S. aureus strains isolated in the 5th-Metropolitan and 10th Regions were 6.2% and 3.7% respectively. On the other hand, a high rate of sensitivity was observed in E. coli with resistance values below 25%. According to these results it is possible to conclude that the mastitis pathogens present in the geographical regions under study are resistant to more than one antimicrobial drug and, therefore, usage of these drugs under medical prescription and implementation of permanent monitoring programs for bacterial resistance are strongly recommended

La quimioterapia antimicrobiana en medicina humana y veterinaria es la principal herramienta terapéutica frente a los microorganismos patógenos causantes de enfermedades infecciosas; sin embargo, con el transcurrir de los años se ha observado la aparición de cepas multiresistentes. Dentro de las medidas utilizadas a nivel mundial para enfrentar este riesgo, están el uso de antimicrobianos bajo receta veterinaria, la rotación en el uso de estos fármacos y la instauración de programas permanentes de monitoreo de la resistencia bacteriana. Este trabajo forma parte de un proyecto de fármacovigilancia de resistencia bacteriana en el ganado lechero, cuyo objetivo fue determinar la sensibilidad en bacterias patógenas aisladas de mastitis en vacas lecheras de la V Región, Región Metropolitana (VR,RM) y X Región (XR), frente a los antimicrobianos utilizados con mayor frecuencia en lecherías del país. Para evaluar la resistencia bacteriana, se utilizó el Método de Dilución en Placa con el fin de determinar la Concentración Mínima Inhibitoria (MIC) de cada cepa bacteriana. En la VR,RM a partir de 963 muestras de leche, se lograron aislar 449 cepas bacterianas, observándose un fuerte predominio de E. coli (40.76%). En la XR, de 2.000 muestras se aislaron 1.012 cepas, observándose un claro predominio de S. aureus (55.53%). Las bacterias grampositivas (Staphylococcus aureus, Streptococcus spp y Staphylococcus coagulasa negativo) presentaron altos porcentajes de resistencia ( 25%), frente a amoxicilina, ampicilina, penicilina, estreptomicina y lincomicina. Para S. aureus, un 6.15% y 3.74% de las cepas aisladas de la VR,RM y XR respectivamente, mostraron resistencia a cloxacilina. Las cepas de E. coli presentaron una mayor sensibilidad, no observándose resistencias superiores al 25%. De los resultados se puede concluir también que las bacterias causantes de mastitis en las regiones en estudio presentan resistencia a más de un antimicrobiano, siendo recomendable que la adquisición de estos fármacos se realice a través de receta veterinaria, instaurando además programas permanentes de monitoreo de resistencia bacteriana en nuestro país