Application of the Verlet method for the simulation of a gravitational system of n bodies

En este trabajo se plantea una solución numérica (simulación por software) del “problema de n cuerpos” que interactúan gravitacionalmente basada en la formulación de Verlet. Adicionalmente se diseña un programa que gráficamente muestra los resultados de esta solución numérica, que detalla las diferentes trayectorias, para diferentes condiciones de masa, velocidad y distancia entre los n objetos que interactúan. La interacción del usuario con la interfaz gráfica, se realiza partícula a partículaIn this paper we propose a numerical solution (software simulation) of the "problem of n bodies" that interact gravitationally based on the formulation of Verlet. Additionally a program is designed that graphically shows the results of this numerical solution, which details the different trajectories, for different conditions of mass, speed and distance between the n objects that interact. The interaction of the user with the graphical interface, is performed particle by particle.Peer Reviewe

Application of the Verlet method for the simulation of a gravitational system of n bodies

In this paper we propose a numerical solution (software simulation) of the "problem of n bodies" that interact gravitationally based on the formulation of Verlet. Additionally a program is designed that graphically shows the results of this numerical solution, which details the different trajectories, for different conditions of mass, speed and distance between the n objects that interact. The interaction of the user with the graphical interface, is performed particle by particle.&nbsp

Dung and Gatrointestinal Nematode Eggs Buried by Euoniticellus intermedius (Reiche) (Coleoptera: Scarabaeidae: Scarabaeinae)

M., Imelda Martínez, Flota-Bañuelos, Carolina, Tokman, Daniel González, Zayas, María del Rosario Ortiz (2018): Dung and Gatrointestinal Nematode Eggs Buried by Euoniticellus intermedius (Reiche) (Coleoptera: Scarabaeidae: Scarabaeinae). The Coleopterists Bulletin 72 (1): 188-194, DOI: 10.1649/0010-065X-72.1.188, URL: http://dx.doi.org/10.1649/0010-065x-72.1.18

Patrón espacio-temporal de larvas y huevecillos de nemátodos gastrointestinales en pastizales ganaderos de Veracruz, México

The spatial and temporal distribution of gastrointestinal nematodes of cattle has been little studied in Mexico. Previous studies have described periods of higher larval presence, vertical and horizontal migration in grasslands, and the frequency of adult nematodes; as well as the effect of pasture trichomes on the migration and survival of Haemonchus larvae. The aim of this study was to determine the time-space layout and spread of gastrointestinal nematode larvae on pasture, and to estimate the effect of ivermectin applied to cattle on the time-dependent abundance of their eggs in a ranch in Veracruz. To determine the spatio-temporal arrangement, monthly morning grass samples were obtained from 30 sampling points from July 2008 to June 2009. Third stage larvae (L3) from each point were counted, and aggregation patterns were estimated through variance/mean and negative binomial K indices. Additionally, the number of eggs per gram in cattle feces was determined, from samples with (CI) and without ivermectin (SI), using standard techniques. A total of 20 276L3 larvae were recovered in the pasture, of which an 80% corresponded to Haemonchus contortus. The highest nematode density with more than 5 000L3/kgDM was detected in October 2008, and the lowest in February and March 2009. The L3 showed an aggregated spatial pattern of varying intensity throughout the year. The number of eggs in the stool was not reduced with the ivermectin application to cattle, which suggested a failure of control. However, the highest parasite loads were observed from July to November 2008. We concluded that the application of ivermectin was not effective to control nematodes eggs, and that L3 populations fluctuated on pasture for ten months, providing an infection source to grazing animals afterwards.El conocer la disposición espacio-temporal y diseminación de las larvas de nematodos gastrointestinales en los pastizales, y estimar el efecto de la ivermectina aplicada a bovinos sobre la abundancia de sus huevecillos, permite estimar dónde y cuándo se presentan las poblaciones más altas, que puede servir para establecer planes de muestreo y orientar medidas de control, así como para definir el riesgo de contaminación de los pastizales de manera diferencial. Para la determinación de la disposición espacio-temporal de L3 en el pastizal, se recolectaron, contaron e identificaron mensualmente las larvas en 30 puntos de muestreo, posteriormente se generaron mapas de disposición espacial con los datos obtenidos de los conteos de L3 en cada punto y mes de muestreo, y se calculó el patrón de disposición mediante los índices varianza/media y K binomial negativa. El número de huevecillos por gramo de heces de los bovinos con (CI) y sin ivermectina (SI), se calculó con la técnica de McMaster. En el pastizal se recuperaron 20 276L3, correspondiendo el 80% a H contortus. En octubre 2008 se detectó la más alta densidad de nematodos con más de 5 000L3/kgMS. Las L3 presentaron un patrón espacial agregado de intensidad variable durante todo el año. Las mayores densidades poblacionales de nematodos fueron en octubre 2008 y las menores en febrero y marzo 2009. La aplicación de ivermectina a los bovinos no redujo el número de huevecillos presentes en las heces, debido a que los tratamientos fueron estadísticamente iguales. De julio a noviembre 2008, se observaron las mayores cargas parasitarias

Productive parameters and carcass yield of rabbits supplemented with Leucaena leucocephala (Lam.) de Wit., and Guazima ulmifolia Lam. foliage: Producción de conejos

Objective: Determine the effect of the inclusion of L. leucocephala and G. ulmifolia foliage on the productive parameters and carcass yield of New Zealand rabbits. Desing/methodology/approach: 30 rabbits (15 females and 15 males) of the New Zealand breed were used, distributed in three treatments (5 females and 5 males), which consisted of feeding 200 g of concentrated food per day + 100 g of fresh L. leucocephala or G. ulmifolia foliage and a control group without supplementation. Results: The total voluntary intake not was affected by the effect of the treatment or sex of the rabbits, an average value of 158.9 g day-1 was recorded. Weight gain was on average 27.2 g day-1. The slaughter weight of the rabbits was on average 2523 g. The carcass weight was 1,297 g and the average carcass yield was 51.6%. The dissectable tier content was lower in the supplemented rabbits (F = 6.70, P=0.001) with values ??of 1.6, 1.8 and 2.11% with fresh foliage of G. ulmifolia, L. leucocephala and without supplementation, this variable was not affected by sex. The proportion of viscera was on average 24.3%. The meat: bone ratio was 5.6 on average. Limitations on study/implications: It was not possible to carry out bromatological analyzes of the foliages or their digestibility. Fingings/conclusions: Supplementation of rabbits with foliage of G. ulmifolia and L. leucocephala decreases the proportion of dissectable gras and does not affect production parameters and carcass yield.Objective: To determine the effect of the addition of Leucaena leucocephala andGuazima ulmifolia foliage on the production parameters and carcass yield of NewZealand rabbits.Desing/methodology/approach: 30 rabbits (15 females and 15 males) of the NewZealand breed were used, distributed in three treatments (five females and five males),which consisted in feeding 200 g of concentrated food per day + 100 g of fresh L.leucocephala or G. ulmifolia foliage, and a control group with no supplementation.Results: The total voluntary intake was not affected by the treatments or gender of therabbits; an average value of 158.9 g day -1 was recorded. Weight gain was 27.2 g day -1on average. The average slaughter weight of the rabbits was 2523 g. The carcassweight was 1,297 g and the average carcass yield was 51.6%. The dissectable fat 2content was lower in rabbits on supplements (F = 6.70, P = 0.001) with values of 1.6, 1.8and 2.11% with fresh foliage of G. ulmifolia, L. leucocephala and withoutsupplementation, this variable was not affected by gender. The viscera proportion wason average 24.3%. The average meat: bone ratio was 5.6.Limitations on study/implications: It was not possible to carry out bromatologicalanalyzes of the foliages or their digestibility.Fingings/conclusions: Supplementation of rabbits with foliage of G. ulmifolia and L.leucocephala decreases the proportion of dissectable fat and did not affect theproduction parameters and carcass yield