Animal group forces resulting from predator avoidance and competition minimization

A new model to explain animal spacing, based on a trade-off between foraging efficiency and predation risk, is derived from biological principles. The model is able to explain not only the general tendency for animal groups to form, but some of the attributes of real groups. These include the independence of mean animal spacing from group population, the observed variation of animal spacing with resource availability and also with the probability of predation, and the decline in group stability with group size. The appearance of "neutral zones" within which animals are not motivated to adjust their relative positions is also explained. The model assumes that animals try to minimize a cost potential combining the loss of intake rate due to foraging interference and the risk from exposure to predators. The cost potential describes a hypothetical field giving rise to apparent attractive and repulsive forces between animals. Biologically based functions are given for the decline in interference cost and increase in the cost of predation risk with increasing animal separation. Predation risk is calculated from the probabilities of predator attack and predator detection as they vary with distance. Using example functions for these probabilities and foraging interference, we calculate the minimum cost potential for regular lattice arrangements of animals before generalizing to finite-sized groups and random arrangements of animals, showing optimal geometries in each case and describing how potentials vary with animal spacing. (C) 1999 Academic Press.</p>

Animal foraging from an individual perspective: an object orientated model

A model system, HOOFS (Hierarchical Object Orientated Foraging Simulator), has been developed to study foraging by animals in a complex environment. The model is implemented using an individual-based object-orientated structure. Different species of animals inherit their general properties from a generic animal object which inherits from the basic dynamic object class. Each dynamic object is a separate program thread under the control of a central scheduler. The environment is described as a map of small hexagonal patches, each with their own level of resources and a patch-specific rate of resource replenishment. Each group of seven patches (0th order) is grouped into a Ist order super-patch with seven nth order super-patches making up a n + 1th order super-patch for n up to a specified value. At any time each animal is associated with a single patch. Patch choice is made by combining the information on the resources available within different order patches and super-patches along with information on the spatial location of other animals. The degree of sociality of an animal is defined in terms of optimal spacing from other animals and by the weighting of patch choice based on social factors relative to that based on food availability. Information, available to each animal, about patch resources diminishes with distance from that patch. The model has been used to demonstrate that social interactions can constrain patch choice and result in a short-term reduction of intake and a greater degree of variability in the level of resources in patches. We used the model to show that the effect of this variability on the animal's intake depends on the pattern of patch replenishment. (C) 1998 Elsevier Science B.V. All rights reserved.</p>

Animal models of diabetic retinopathy

Diabetic retinopathy (DR) is a major cause of visual impairment worldwide. The precise pathogenesis of this diabetic complication remains ill-defined and this is reflected in the limited options for preventing development and progression of this disease. The value of animal models to understand and treat human disease is well recognised and this chapter focuses on the range of in vivo model systems that are available for studying DR. These models have been developed over many decades and utilised to aid our understanding of what causes DR, about how microvascular and neural lesions develop and to provide evidence for key cellular and molecular mechanisms that drive this pathology. A wide range of animal models of DR are currently available, each with advantages and disadvantages that need to be understood and evaluated for their scientific and clinical value. As transgenic and imaging technology improves, more models will be developed and they will continue to play a critical role in the development of new therapeutic approaches to DR by providing robust, preclinical evidence prior to clinical trial.

Observatorio social de Bogotá: la educación básica y media en Bogotá, 2007. N. 21 julio de 2008

Gestión del conocimiento

Progress and Challenges in Animal Handling and Slaughter in the U.S.

The article discusses the McDonald's Corporation audit and the ways to improve the handling of livestock on the way to slaughter.

Biotechnology and Animal Welfare

The articles discusses "processes which require the manipulation of genetic material to produce a substance which is administered to a farm animal or manipulation of the animal's own genetic material". The last section focuses on the ethical questions "from the viewpoint of the author who has had years of experience...".

Identificación de factores de riesgo para crisis familiar en una comunidad sub-urbana

Tesis (Maestría en Enfermería, con Especialidad en Salud Comunitaria) UANL

La Facultad de Enfermería de la U.A.N.L. desde sus orígenes a la actualidad 1915-1990 : 75 años de presencia de la enfermería en el estado de Nuevo León, una visión panorámica

Tesis (Maestría en Educación Superior) UANL

La participación en la educación de adultos : (Experiencia en el barrio Guachupita)

Tesis (Maestría en Formación y Capacitación de Recursos Humanos) UANL

La educación no formal de adultos en Costa Rica : un panorama de instituciones y sus programas

Tesis (Maestría en Educación de Adultos) (UANL)

Caracterización y evaluación del bosque natural del pino azul (Pinus maximartinezii Rzed) en el cerro de Piñones de Juchipila, Zacatecas

Tesis (Maestría en Ciencias en Producción Agrícola) UANL

Sensibilidad de Mycrobacterium tuberculosis a estreptomicina e isoniacida determinada por cromatografía de líquidos de alta resolución y por dilusión y siembra en placa

Tesis (Maestría en Ciencias con Especialidad en Química Analítica) UANL

Diseño de una práctica de laboratorio de física : fuerzas en equilibrio

Tesis (Maestría en Ciencias de Ingeniería Mecánica con Esecialidad en Diseño Mecánico) UANL

Eficiencia en el proceso del producto carne seca : consumo en Monterrey y su área metropolitana

Tesis (Maestría en Salud Pública con Especialidad en Nutrición Comunitaria) UANL