Seroprevalence and risk factors for Neospora caninum in small dairy farms in central Chile

Indexación: Scopus.Objetivos. Proveer información sobre la seroprevalencia y factores de riesgo asociados a la infección por Neospora caninum en bovinos en Chile central. Materiales y métodos. La población estudiada corresponde a pequeñas lecherías que son parte de un programa gubernamental de Asistencia Técnica (SAT), en la región de O´Higgins en Chile central. Muestras de suero fueron recolectadas desde vacas en lactancia y analizadas mediante un kit comercial ELISA. Además, se aplicó un cuestionario a los dueños de los animales para la identificación de factores de riesgo a través de regresión logística. Resultados. Se identificó una prevalencia a nivel de granja del 67%, mientras que dentro de las granjas positivas, esta fue en promedio de 55%. El historial de abortos (p= 0.037, OR=5.09), la fuente de alimentación de perros (p= 0.0429, OR=6), la fuente de agua de bebida de las vacas (p=0.034, OR=4.5) y el manejo de los abortos (p=0.017, OR=7.43) fueron identificados como factores de riesgo para la infección. Conclusiones. Se observa una alta seroprevalencia de N. caninum en pequeños productores lecheros pertenecientes al SAT en Chile central. Los resultados presentados resaltan la necesidad de mejorar las acciones de vigilancia de esta enfermedad y el desarrollo de medidas preventivas para evitar las pérdidas asociadas a esta enfermedad.Objective. To provide information about seroprevalence and risk factors of Neospora caninum infection in bovines of central Chile. Material and Methods. The study population are small dairy farms that are part of a Government Technical Support Service (SAT) in the O'Higgins region in central Chile. Sera samples were collected from milking cows and analyzed by a commercial ELISA kit. Additionally, a questionnaire was applied to farmers to identify risk factors through logistic regression. Results. The farm level prevalence was found to be 67%, and within farms seroprevalence 55%. Abortion history (p= 0.037, OR=5.09), dogs feed source (p= 0.0429, OR=6), cattle drinking water source (p=0.034, OR=4.5) and abortions management (p=0.017, OR=7.43) were found as significant risk factors for infection. Conclusion. There is a high N. caninum seroprevalence in small SAT's dairy farms in O'Higgins region. These results highlight the need of improving N. caninum surveillance, and the development of preventive measures to avoid losses related with this disease.http://revistas.unicordoba.edu.co/index.php/revistamvz/article/view/92

Sistema de enfoque basado en dos espejos elípticos y un espejo plano rotatorio para un radar a 300 GHz

A focusing system for a 300 GHz radar with two target distances (5m and 10m) is proposed, having 1cm resolution in both cases. The focusing system is based on a gaussian telescope scheme and it has been designed using gaussian beam quasi-optical propagation theory with a homemade Matlab analysis tool. It has been translated into a real focusing system based on two elliptical mirrors and a plane mirror in order to have scanning capabilities and validated using the commercial antenna software GRAS

Seroprevalence and risk factors for Neospora caninum in small dairy farms in central Chile

ABSTRACT Objective. To provide information about seroprevalence and risk factors of Neospora caninum infection in bovines of central Chile. Material and Methods. The study population are small dairy farms that are part of a Government Technical Support Service (SAT) in the O´Higgins region in central Chile. Sera samples were collected from milking cows and analyzed by a commercial ELISA kit. Additionally, a questionnaire was applied to farmers to identify risk factors through logistic regression. Results. The farm level prevalence was found to be 67%, and within farms seroprevalence 55%. Abortion history (p= 0.037, OR=5.09), dogs feed source (p= 0.0429, OR=6), cattle drinking water source (p=0.034, OR=4.5) and abortions management (p=0.017, OR=7.43) were found as significant risk factors for infection. Conclusion. There is a high N. caninum seroprevalence in small SAT´s dairy farms in O´Higgins region. These results highlight the need of improving N. caninum surveillance, and the development of preventive measures to avoid losses related with this disease.RESUMEN Objetivos. Proveer información sobre la seroprevalencia y factores de riesgo asociados a la infección por Neospora caninum en bovinos en Chile central. Materiales y métodos. La población estudiada corresponde a pequeñas lecherías que son parte de un programa gubernamental de Asistencia Técnica (SAT), en la región de O´Higgins en Chile central. Muestras de suero fueron recolectadas desde vacas en lactancia y analizadas mediante un kit comercial ELISA. Además, se aplicó un cuestionario a los dueños de los animales para la identificación de factores de riesgo a través de regresión logística. Resultados. Se identificó una prevalencia a nivel de granja del 67%, mientras que dentro de las granjas positivas, esta fue en promedio de 55%. El historial de abortos (p= 0.037, OR=5.09), la fuente de alimentación de perros (p= 0.0429, OR=6), la fuente de agua de bebida de las vacas (p=0.034, OR=4.5) y el manejo de los abortos (p=0.017, OR=7.43) fueron identificados como factores de riesgo para la infección. Conclusiones. Se observa una alta seroprevalencia de N. caninum en pequeños productores lecheros pertenecientes al SAT en Chile central. Los resultados presentados resaltan la necesidad de mejorar las acciones de vigilancia de esta enfermedad y el desarrollo de medidas preventivas para evitar las pérdidas asociadas a esta enfermedad

Seroprevalencia y factores de riesgo de Neospora caninum en pequeñas granjas lecheras de la zona central de Chile

Objective. To provide information about seroprevalence and risk factors of Neospora caninum infection in bovines of central Chile. Material and Methods. The study population are small dairy farms that are part of a Government Technical Support Service (SAT) in the O´Higgins region in central Chile. Sera samples were collected from milking cows and analyzed by a commercial ELISA kit. Additionally, a questionnaire was applied to farmers to identify risk factors through logistic regression. Results. The farm level prevalence was found to be 67%, and within farms seroprevalence 55%. Abortion history (p= 0.037, OR=5.09), dogs feed source (p= 0.0429, OR=6), cattle drinking water source (p=0.034, OR=4.5) and abortions management (p=0.017, OR=7.43) were found as significant risk factors for infection. Conclusion. There is a high N. caninum seroprevalence in small SAT´s dairy farms in O´Higgins region. These results highlight the need of improving N. caninum surveillance, and the development of preventive measures to avoid losses related with this disease.Objetivos. Proveer información sobre la seroprevalencia y factores de riesgo asociados a la infección por Neospora caninum en bovinos en Chile central. Materiales y métodos. La población estudiada corresponde a pequeñas lecherías que son parte de un programa gubernamental de Asistencia Técnica (SAT), en la región de O´Higgins en Chile central. Muestras de suero fueron recolectadas desde vacas en lactancia y analizadas mediante un kit comercial ELISA. Además, se aplicó un cuestionario a los dueños de los animales para la identificación de factores de riesgo a través de regresión logística. Resultados. Se identificó una prevalencia a nivel de granja del 67%, mientras que dentro de las granjas positivas, esta fue en promedio de 55%. El historial de abortos (p= 0.037, OR=5.09), la fuente de alimentación de perros (p= 0.0429, OR=6), la fuente de agua de bebida de las vacas (p=0.034, OR=4.5) y el manejo de los abortos (p=0.017, OR=7.43) fueron identificados como factores de riesgo para la infección. Conclusiones. Se observa una alta seroprevalencia de N. caninum en pequeños productores lecheros pertenecientes al SAT en Chile central. Los resultados presentados resaltan la necesidad de mejorar las acciones de vigilancia de esta enfermedad y el desarrollo de medidas preventivas para evitar las pérdidas asociadas a esta enfermedad.FONDECYT, 1112126

Fiber-Coupled 2-D n-i-pn-i-p Superlattice Photomixer Array

We have fiber-coupled an array of n-i-pn-i-p superlattice photomixers using a fiber array of same pitch of 145 mu m. We experimentally investigate the effect of the finite size of the implemented silicon lens on the interference between the array elements in the far field. We compare the results from a geometry optimized for a collimated terahertz (THz) beam to theory and simulations. Further, beam steering is demonstrated by controlling the optical phase of the individual photomixers. Due to broadband antennas attached to each array element, the array is frequency tunable. It is exemplarily characterized at 165 and 310 GHz. Such arrays can overcome power limitations of individual photomixers. In contrast to bulky individually packaged free space solutions, this array can be packaged to a compact terahertz source, limited in size only by the size of the silicon lens. The investigated 2 x 2 array features a spot diameter (full-width at half-maximum) of 12.1 mm at a distance of 19 cm at 310 GHz with a silicon lens of only 20-mm diameter

Dielectric rod waveguide as an enabling technology for THz frequencies

A dielectric rod waveguide (DRW) made of high-dielectric-constant material such as sapphire, GaAs or Si has in the past been shown to have low transmission loss and good matching with a rectangular metal waveguide at millimetre wavelengths. Also various passive components have been demonstrated. Recently, it has been demonstrated that a single DRW antenna works well over several rectangular waveguide bands even up to 1 THz. Also first attempts have been made to integrate a photo mixer with a DRW waveguide to produce an effective THz source

An Antenna-free Device for Continuous-Wave THz Emission: Vertical Large Area Emitter

In this contribution, a new room-temperature terahertz source is proposed for overcoming the power limitations inherent to photomixer-based generators. Specifically, a manufactured vertical "large area emitters" is described and analyzed by proposing a Hertzian dipole array model. An estimation of its radiation pattern is included and will be compared with experimental measurements

Ultra-wideband Dielectric Rod Waveguide antenna as photomixer-based THz emitter

In this contribution, the use of Dielectric Rod Waveguide antennas integrated with a THz photomixer-based emitter is studied. This topology presents a cost-affordable alternative to dielectric lenses for reducing losses caused by scattering into the substrate and reflection in the semiconductor-air interface. For increasing the bandwidth, the use of planar dielectric lens embedded into the rod is proposed

From Arrays of THz Antennas to Large-Area Emitters

Arrays of coherently driven photomixers with antenna (antenna emitter arrays, AEAs) have been evaluated as a possibility to overcome the power limitations of individual conventional photomixers with antenna ("antenna emitters", AEs) for the generation of continuous-wave (CW) THz radiation. In this paper, "large area emitters" (LAEs) are proposed as an alternative approach, and compared with AEAs. In this antenna-free new scheme of photomixing, the THz radiation originates directly from the acceleration of photo-induced charge carriers generated within a large semiconductor area. The quasi-continuous distribution of emitting elements corresponds to a high-density array and results in favorable radiation profiles without side lobes. Moreover, the achievable THz power is expected to outnumber even large AEAs. Last not least, the technological challenge of fabricating LAEs appears to be significantly less demanding

Photonic-Based Integrated Sources and Antenna Arrays for Broadband Wireless Links in Terahertz Communications

This paper analyzes integrated components for ultra-broadband millimeter-wave wireless transmitters enabling the 5 G objective to increase the wireless data rates 10× to 100×. We have pursued the photonic-based approach to generate the millimeter-wave carrier (≈97 GHz in this paper) through photomixing. We have achieved up to 10 Gb s-1 data rate using an OOK modulation format (to reduce latency) and either direct detection (DD) or coherent detection. We show that coherent detection enables a sensitivity improvement of 17 dB over DD. We also demonstrate in this work that such improvement can be achieved using as the transmitter a novel integrated antenna array - the self-complementary chessboard array. This avoids the use of complex coherent schemes at the receiver, enabling simple DD for ultra-broadband links