Low level rf system for the European Spallation Source's Bilbao linac

Design and some performance results of the pulsed digital low level radio frequency (LLRF) for the radio frequency quadrupole (RFQ) systems of Rutherford Appleton Laboratory-front end test stand and the future European Spallation Source Bilbao linac are presented. For rf field regulation, the design is based on direct rf-to-baseband conversion using an analog in-phase quadrature (IQ) demodulator, high-speed sampling of the I/Q components, baseband signal processing in a field-programmable gate array (FPGA), conversion to analog, and IQ modulation. This concept leads to a simple and versatile LLRF system which can be used for a large variety of rf frequencies and virtually any LLRF application including cw, ramping, and pulsed. In order to improve the accuracy of the probe voltage measurement, errors associated with the use of analog IQ demodulators have been identified and corrected by FPGA algorithms and proper setting of the feedback loop parameters. Furthermore, a baseband-equivalent model for the rf plant is developed in MATLAB-Simulink to study the RFQ transient response under beam loading in the presence of phase and delay errors. The effect of the unwanted resonant modes on the feedback loop stability and the LLRF considerations to avoid such instabilities are discussed and compared to some other machines such as the ILC and the European free electron laser. The practical results obtained from tests with a mock-up cavity and an RFQ cold model verify that amplitude and phase stabilities down to a fraction of one percent and one degree and phase margins larger than ±50° can be achieved with this method preserving the linearity and bandwidth of the feedback loops. © 2011 American Physical Society.Peer Reviewe

Actualización en radiología dental: Radiología convencional Vs digital

Desde su incorporación a la práctica odontológica la radiología digital ha experimentado un importante desarrollo. El continuo avance de las tecnologías en las que se sustenta ha dotado a estos sistemas de interesantes prestaciones que pueden facilitar el diagnóstico y manejo de imágenes radiográficas. Con estos avances la radiología digital ha despertado un interés creciente entre los profesionales de la odontología, especialmente durante los últimos años, en los que ha aumentado notoriamente tanto la cantidad de sistemas comercializados como el número de odontólogos que han decidido sustituir la radiología convencional por un sistema digital en sus clínicas. En esta revisión de la literatura se tratará de ofrecer una visión actualizada de los distintos sistemas disponibles en la actualidad, así como una comparativa entre ellos basada en estudios publicados recientemente. Since its appearance in dentistry, digital radiology has experienced a notorious development. A constant advance in the corresponding technologies has enhanced these digital systems with interesting features which may facilitate radiological diagnosis and image management. Due to these advances digital radiology has elicited a growing interest in dentistry. Specially during the last years there has been an increase both in the amount of available systems and in the number of dentists who have incorporated a digital system in their offices. This literature review aims to offer an updated view of the available systems and a comparison of them based in recent studies

Camel genetic resources conservation through tourism: A key sociocultural approach of camelback leisure riding

Camels are exotic elements, which can be comprised within adventure travel companies promoting ecotourism activities. Such recreations contribute to sustainable livelihoods for local communities and educational empowerment towards nature and its conservation. At present, some local camel breeds’ survival reduces to this animal-based leisure industry and its reliability to perform and promote customized services accurately. By conducting an on-site questionnaire to customers participating in camelback riding tours, we assessed the motivational factors affecting participation, satisfaction, and loyalty in this tourism segment that may have made it socially differentiated. The sixfold combination of staff performance, culture geography, diverse and humane close interaction, camel behavior and performance, sociotemporal context, and positive previous experience involves the elemental dimensions that explain customer satisfaction and return intention probability within this entertainment business. Customer knowledge is essential for stakeholders to build personalized riding experiences and align profits with environmental sustainability and biodiversity mainstream concerns into their everyday operations. In turn, domestic camel tourist rides could be managed as a viable path to nature conservation by helping endangered local breeds to avoid their functional devaluation and potential extinction

Razas autóctonas de las islas canarias: pasado, presente y futuro

We describe the means developed by official and private institutions for the conservation of Canary Breeds. We evaluate the response to concrete actions comparing the evolution of their census with presented at the Warwick Conference (1989).Se describen la evolución de las Razas autóctonas canarias y las medidas que se han de tomar de cara al futuro, tanto por organismos oficiales como por entidades particulares, para evitar el peligro de desaparición de dichas razas

Origen, migraciones y relaciones filogenéticas de las razas ganaderas de Andalucía Oriental

Nuestra región a lo largo de la historia se ha visto invadida, conquistada o visitada por una gran variedad de culturas, que provenientes de Africa, el Mediterráneo, o resto de Europa se instalaron en nuestra tierra. Estos pobladores, desde los antiguos Íberos, pasando por los Fenicios, Tartesos y Romanos hasta llegar a los Árabes y los Castellanos, trajeron consigo unas poblaciones de animales que contribuyeron a la formación de la gran variedad actual de razas autóctonas en Andalucía. En este trabajo realizaremos una descripción del origen de las razas autóctonas ovinas, caprinas, bovinas y porcinas de Andalucía Oriental teniendo en cuenta sus vías de acceso y distribución a lo largo de los distintos periodos históricos y sus relaciones filogenéticas, haciendo un análisis de la influencia de estas razas en el mantenimiento del equilibrio ecológico y poblacional de los espacios donde tradicionalmente se han venido explotando

Optimization of RNA concentration for genome editing by CRISPR in rabbit zygotes

Site-specific genetic modification aiming to delete (knock-out) a gene provides an unequivocal answer to elucidate the function of such particular gene in the whole organism. Site-specific genetic modification has been achieved by homologous recombination, generally in embryonic stem cells, which has made the mouse the most widely used mammalian model

Experimental evidence of a cluster-glass transition on the colossal magnetoresistance manganite La0.7Pb0.3(Mn0.9Fe0.1)O3

4 págs.; 3 figs. ; PACS numberssd: 75.40.2s, 75.47.2m, 61.12.Ex, 61.46.1wNeutron small angle scattering on a colossal magnetoresistance material shows clear signatures of a rise in characteristic length of paramagnetic fluctuations as the maximum of dc susceptibility is approached from high temperatures. The phenomenon is accompanied by a rise in intensity of a broad peak that appears at wave vectors of ≈ 0.025-1, and this is interpreted as a fingerprint of the onset of ferromagnetic ordering due to intercluster magnetic interactions. © 2005 The American Physical Society.Peer Reviewe