Vulnerability Assessment and Re-routing of Freight Trains Under Disruptions: A Coal Supply Chain Network Application

In this paper, we present a two-stage mixed integer programming (MIP) interdiction model in which an interdictor chooses a limited amount of elements to attack first on a given network, and then an operator dispatches trains through the residual network. Our MIP model explicitly incorporates discrete unit flows of trains on the rail network with time-variant capacities. A real coal rail transportation network is used in order to generate scenarios to provide tactical and operational level vulnerability assessment analysis including rerouting decisions, travel and delay costs analysis, and the frequency of interdictions of facilities for the dynamic rail system

Prevalencia de helicobacter pylori en el servicio de endoscopia digestiva del centro de especiales médicas Montoya y en Hopistal Bautista en el período enero a julio 2008

Tesis (Doctor en Medicina y Cirugia)--Universidad Americana, Managua, 2009El objetivo de este estudio descriptivo es el de determinar la prevalencia de Helicobacter Pylori y características generales de los pacientes atendidos por sintomatología acido péptica a los cuales se les realizó endoscopía digestiva alta más biopsia gástrica en el Hospital Bautista de Managua (HB) y el Centro de Especialidades Médicas Montoya (CEM)

Analysis of efficiency and profitability of franchise services

The present study analyses the relative efficiency of franchise services and characterises the best companies, confirming the relationship between efficiency and profit. These companies are from the trade and other services sector , the main group of service-providing companies in the Spanish economy. The methodology calls for first comparing the relative efficiency of franchisers and ownership enterprises. Second, the focus turns to the most efficient franchise services, using a super-efficiency model to rank them. The paper then goes on to cover the analysis of the main characteristics of the best franchise enterprises, the number of own establishments in a franchise business and the profitability of the company. This paper presents arguments as to why companies from the trade and other services sector are included. The main conclusion is that, whilst the number of establishments is irrelevant in achieving greater efficiency, many of the most efficient enterprises have high returns.García Martin, CJ.; Medal Bartual, A.; Peris-Ortiz, M. (2014). Analysis of efficiency and profitability of franchise services. Service Industries Journal. 34(9):796-810. doi:10.1080/02642069.2014.905921S79681034

Perspectivas sobre la eficiencia del sistema portuario español

La Ley 33/2010, de 5 de agosto, señala explícitamente “la exigencia de adoptar en España medidas que mejoren la gestión de nuestros puertos y su eficiencia, impulsando su competitividad en una coyuntura de fuerte competencia internacional”. Con este objeto, el presente artículo analiza las perspectivas futuras sobre la eficiencia de los puertos que integran el actual Sistema Portuario Español, tanto a corto como a medio plazo. Con ello pretendemos dar respuesta a cuestiones cómo qué nivel de eficiencia van a tener los puertos españoles en el futuro, qué puertos van a liderar el panorama portuario español en los próximos años, o cuál será el ranking jerárquico de dichas entidades en función de su nivel de eficiencia. Las respuestas a las mismas permitirán a los gestores portuarios tomar las medidas oportunas para mejorar la gestión de los puertos en la línea propuesta por la citada Ley. Para el análisis de la eficiencia previsible del Sistema Portuario Español hemos aplicado la metodología DEA con tolerancias, partiendo de las previsiones realizadas por el Organismo Público Puertos del Estado y recogidas en el Plan Estratégico de Infraestructuras y Transportes del 2009

Gratiana boliviana (Coleoptera: Chrysomelidae) does not feed on Jamaican nightshade Solanum jamaicense (Solanaceae)

Jamaican nightshade has been in Florida for at least 77 years, but is considered rare and only found in 4 counties in the central peninsula. However, there are many examples of long lag periods between the time an exotic plant arrives at a new location, and the time it spreads and becomes highly invasive (Sakai et al. 2001). Locally dense populations of Jamaican nightshade in hammock areas in Saint Lucie and Osceola counties suggest that the plant is adapted to at least some habitats in Florida, and could eventually spread to similar habitats and become a serious exotic invader. The current study demonstrated that G. boliviana, a biological control agent established in Florida for control of tropical soda apple, does not utilize Jamaican nightshade for feeding or oviposition. If Jamaican nightshade becomes a more serious invasive weed in the future, it may be possible to identify host specific natural enemies from its native range

The effect of Gratiana boliviana (Coleoptera: Chrysomelidae) herbivory on growth and population density of tropical soda apple (Solanum viarum) in Florida

The effect of herbivory by Gratiana boliviana Spaeth (Coleoptera: Chrysomelidae) on the invasive, tropical soda apple (TSA) (Solanum viarum Dunal, Solanaceae), was investigated using exclusion methods and by monitoring the density of G. boliviana and the weed at four locations over a period of 40 months. TSA plants protected by insecticide were taller, wider, and had greater canopy cover that unprotected plants, and plants in closed cages were taller and wider than those in open cages. Survival of plants was higher in plots protected with insecticide than in unprotected plots in both years of a 2-year study. In the population dynamics study, the initial density of TSA was 4-5 times higher at one of the locations than at the other three sites, but within 3 years, TSA density at the high density site had declined by 90%. At the three sites which initially had a low abundance of TSA, density remained low throughout the study. The intrinsic rate of increase of G. boliviana varied between -3.9 and 4.5, but over the 3-year study, was not different from zero, indicating a stable population. The intrinsic rate of increase was lower than zero for the period from October to January, and greater than zero during the January to April period. In the periods from April to July and July to October, the rate of increase was not different from zero. The implications of these results for biological control of TSA in Florida are discussed. © 2010 Taylor & Francis

Un análisis de la eficiencia de los puertos españoles

En este trabajo se desarrolla una aplicación del modelo del Data Envelopment Analysis (DEA), o análisis de la eficiencia relativa, a los diferentes puertos españoles. Después de una breve referencia a la metodología de estos tipos de análisis (un método de optimización), se discuten las diversas alternativas que para resolver el modelo es posible utilizar. Asimismo se valora la conveniencia de utilizar optimizadores específicos o bien un software de propósito general. Para finalizar se analiza la eficiencia relativa de la actividad portuaria en los diferentes puertos durante los últimos años para medir su evolución temporal