Fully-Metallic Additively Manufactured Monolithic Double-Ridged Waveguide Rotman Lens in the K/Ka-Band.

This paper reports on the design and experimental validation of a fully-metallic double-ridged waveguide 10 × 10 Rotman lens additively manufactured as a single part. The wide band operation of this quasi-optical beamformer enables us to cover the uplink and downlink frequencies allocated to satellite communications in the K/Ka-band, from 17.3 GHz to 30 GHz. The feeding port design was adjusted to enable vertical printing, thus minimizing the use of supporting structures. A prototype was manufactured and tested. The reported results indicate losses in the range of 0.5 dB in the lower-frequency band and 0.8 dB in the upper-frequency band, including the waveguide transitions added for test purposes. The measured reflection and coupling coefficients remain below -11.5 dB over the operating band. The standard deviation of the residual phase error across the array ports is below 5° in simulation and below 10° in measurements. Array factors synthesized using the scattering parameters confirm the good stability of the beamforming functionality over the wide frequency band analyzed. This monolithic design is a promising step toward more integrated antenna systems, such as a compact dual-stack configuration for planar array design.

Additive manufacturing in compact high-gain wideband antennas operating in mm-wave frequencies.

A wideband dual-reflector 3D-printed antenna is proposed to operate in the mm-Wave band. The design is based on a Cassegrain reflector optics but including a dielectric piece for merging the feeding system and the support structure of the subreflector. The operational principle of this antenna is presented, as well as the design parameters. Then, a prototype to operate at Ka-band is manufactured combining a 3D-printed technique using PLA as printable material and a spray to coating the antenna, providing a low-cost affordable solution. The different pieces of the antenna are evaluated, and the antenna is also measured in a spherical compact range. An excellent agreement between simulations and measurements is obtained, resulting in a [Formula: see text] of operational bandwidth. These results validate the use of coating procedures and the design technique at these demanding frequencies. Its operation shows a stable gain in the entire Ka-band (including [Formula: see text] and [Formula: see text]), which makes the antenna as a suitable light, low-cost, and broadband solution for mm-Wave applications.

Utilidad estadística de los estudios de farmacovigilancia para evaluar reacciones adversas a medicamentos

Introducción: la detección oportuna y la evaluación de las reacciones adversas de los medicamentos es cada vez más importante. En Cuba existe la necesidad de profundizar y extender con alcance nacional los estudios de Farmacovigilancia, por tal motivo se expone como objetivo fundamentar sustentados en la estadística el uso de estudios de farmacovigilancia para la detección, registro, notificación y evaluación de las sospechas de las reacciones adversas de los medicamentos valorando su seguridad. Desarrollo: se brinda un resumen de tipos de estudios de farmacovigilancia con ejemplos de objetivos de investigaciones realizadas y publicadas en revistas científicas posibles a considerar y aplicar a las condiciones reales que tenga cada investigador, se presentan variables que ya han sido establecidas en otros estudios que se deben tener en cuenta para estudiar seguridad de los medicamentos y técnicas estadísticas teniendo en cuenta los tipos de variables a relacionar. Conclusiones: se concluye que resulta un logro científico conocer formas de profundizar y extender los estudios de Farmacovigilancia para tomar conocimiento de la seguridad de los fármacos y promover un uso racional, científico y adecuado de los mismos, en beneficio de la comunidad.

Introduction: timely detection and evaluation of adverse drug reactions is increasingly important. In Cuba there is a need to deepen and extend pharmacovigilance studies nationwide. That is why it is stated, based on statistics, the use of studies for the detection, registration, notification and evaluation of suspected adverse drug events, assessing their safety. Development: a summary of types of pharmacovigilance studies is provided with examples of objectives of research works already done and published in scientific magazines likely to consider and use in actual conditions each researcher has, and there are also presented variables that have already been established in other studies, which must be taken into account to study drug safety and statistical techniques considering the types of variables to be related. Conclusion: it is concluded that knowing ways to deepen and spread the Pharmacovigilance studies in order to be aware of drug safety and foster their rational, scientific and adequate use in the interests of the community is indeed a scientific accomplishment.

Introdução: a detecção e avaliação oportunas de reações adversas a medicamentos está se tornando cada vez mais importante. Em Cuba há uma necessida de de aprofundar e ampliar os estudos de farmacovigilância com âmbito nacional, por esta razão é declarado como um objetivo fundamentar com base em estatísticas o uso de estudos de farmacovigilância para a detecção, registro, notificação e avaliação de suspeitas de reações adversas de medicamentos que avaliam sua segurança. Desenvolvimento: um resumo dos tipos de estudos de farmacovigilância é fornecido com exemplos de objetivos de pesquisa realizados e publicados em possíveis revistas científicas a serem consideradas e aplicadas às condições reais que cada pesquisador possui, variáveis que já foram estabelecidas em outros estudos que devem ser levadas em conta para estudar a segurança de medicamentos e técnicas estatísticas levando em conta os tipos de variáveis a serem relacionadas. Conclusões: conclui-se que é uma conquista científica conhecer formas de aprofundar e ampliar os estudos de farmacovigilância para tomar conhecimento da segurança dos medicamentos e promover um uso racional, científico e adequado dos mesmos, em benefício da comunidade.

Evaluation of a Dielectric-Only Transmitarray for Generating Multi-Focusing Near-Field Spots Using a Cluster of Feeds in the Ka-Band.

A transmitarray antenna is evaluated to generate a multi-focusing spot area in the Fresnel region of the antenna in the Ka-band. The antenna is designed to focus the radiated field at a certain point using a central feeding configuration. The number of feeds is increased to create as many focusing spots as feeds. The feeds are placed along an arc defined in the principal planes of the transmitarray, radiating independent near-field spots and providing a solution with a wide-angle spot scanning without an antenna displacement and a high isolation between feeds. To validate this concept, a transmitarray based on dielectric-only cells is designed and simulated under full-wave conditions. Then, this design is manufactured using a 3D printing technique, and the prototype is measured in a planar acquisition range. Measurements are performed for different feed positions in order to validate the multi-focusing capability of the antenna. Measurements and simulations show a high agreement and validate the proposed design technique.

Reflectarray antennas: a smart solution for new generation satellite mega-constellations in space communications.

One of the most ambitious projects in communications in recent years is the development of the so-called satellite mega-constellations. Comprised of hundreds or thousands of small and low-cost satellites, they aim to provide internet services in places without existing broadband access. For the antenna subsystem, reflectarrays have been proposed as a cheap solution due to their low profile and manufacturing costs, while still providing good performance. This paper presents a full design of a reflectarray antenna for mega-constellation satellites with a shaped-beam isoflux pattern for constant power flux in the surface of the Earth. A unit cell consisting of two stacked rectangular microstrip patches backed by a ground plane is employed, providing more than 360° of phase-shift. The generalized intersection approach optimization algorithm is employed to synthesize the required isoflux pattern in a 2 GHz bandwidth in Ku-band. To that purpose, a full-wave electromagnetic analysis is employed for the wideband design. The optimized reflectarray layout complies with the specifications of the isoflux pattern in the frequency band 16 GHz-18 GHz, demonstrating the capabilities of this type of antenna to provide a low-cost, low-profile solution for the user beam segment, including different types of shaped beams.

El trabajo independiente. Una herramienta cognoscitiva en la asignatura Metodología de Investigación y Estadística de Estomatología / The independent work. A cognitive tool in the subject Stomatology Research and Statistics Methodology

Introducción: el trabajo independiente forma parte del proceso de enseñanza aprendizaje, es uno de los medios más efectivos para el desarrollo de la actividad cognoscitiva del estudiante por el nivel de independencia y concientización del proceso, lo que le permite alcanzar la mayor profundización científica en el conocimiento y el desarrollo de habilidades. Objetivo: evaluar el trabajo independiente para el desarrollo de la independencia cognoscitiva de los estudiantes y sus resultados docentes. Método: se realizó un estudio descriptivo trasversal para evaluar los criterios de los estudiantes de cómo perciben las orientaciones y el control del trabajo independiente por parte del profesor en su desarrollo cognoscitivo y los resultados docentes en la asignatura. Resultados: los estudiantes tienen una percepción buena de cómo reciben las orientaciones y el control del trabajo independiente para su desarrollo cognoscitivo, se obtuvo una promoción del 100 por ciento al finalizar el curso, con una calidad del 92 por ciento. Conclusiones: el trabajo independiente bien orientado y controlado estimula la independencia, la conformación de hábitos de autopreparación en los estudiantes y motiva la actividad creadora con la consecuente responsabilidad en los resultados docentes(AU)

Introduction: independent work is part of the teaching-learning process, it is one of the most effective means for the development of the students cognitive activity by the level of independence and awareness of the process, which allows them to achieve the greatest scientific deepening in the knowledge and skills development. Objective: to evaluate the independent work for the development of the cognitive independence of the students and their teaching results. Method: a cross-sectional descriptive study was carried out to evaluate the students' criteria of how they perceive the orientations and the control of independent work by the teacher in their cognitive development and the teaching results in the subject. Results: the students have a good perception of how they receive guidance and control of independent work for their cognitive development, a 100 percent promotion was obtained at the end of the course, with a quality of 92 percent. Conclusions: well-oriented and controlled independent work stimulates independence, the formation of self-preparation habits in students and motivates creative activity with the consequent responsibility for teaching results(EU)

Dual-Polarization Ku-Band Compact Spaceborne Antenna Based on Dual-Reflectarray Optics.

This article demonstrated an accurate analysis technique for dual-reflectarray antennas that take into account the angle of incidence of the impinging electric field on the main reflectarray cells. The reflected field on the sub and the main reflectarray surfaces is computed using Method of Moments in the spectral domain and assuming local periodicity. The sub-reflectarray is divided into groups of elements and the field radiated by each group is used to compute the incident and reflected field on the main reflectarray cells. A 50-cm demonstrator in Ku-band that provides European coverage has been designed, manufactured and tested to validate the analysis technique. The measured radiation patterns match the simulations and they fulfill the coverage requirements, achieving a cross-polar discrimination better than 25 dB in the frequency range: 12.975-14.25 GHz.

Un ejemplo de cómo hacer extensión universitaria

El objetivo de este trabajo consistió en lograr una integración de las comunidades intra y extrauniversitarias a través de la creación de un Círculo de interés de informática con los estudiantes del Politécnico de Informática de Manzanillo, con vista a prepararlos para su futuro desempeño profesional. Para alcanzar este objetivo se elaboró un programa para este círculo de interés, actividad sin precedentes en las Universidades de Ciencias Médicas en Cuba. Para la validación de este programa se escogieron al azar diez (10) estudiantes de dicho Politécnico. Se les realizó un diagnóstico inicial donde se pudo comprobar el poco conocimiento básico de esta materia. Hay que tener en cuenta que los encuentros comenzaron a finales de curso. Al cabo de tres meses se logró ampliar los conocimientos de estos estudiantes y lograron realizar una exposición donde realizaron las presentaciones en Power Point(AU)

Ligadura endoscópica subfacial de venas perforantes: descripción de la técnica y presentación de nuestra experiencia / Subfascial endoscopic ligation of perforant veins: description of technique and our experience

Las úlceras venosas crónicas de las extremidades inferiores tratadas en forma conservadora presentan un alto índice de recidivas, y la técnica descrita por Linton en 1938 se encuentra prácticamente abandonada por las complicaciones de las heridas y las largas estadías hospitalarias. Desde que Hauer en 1985 introdujo la técnica de ligadura endoscópica subfascial de venas perforantes (SEPS), se han publicado diferentes abordajes y variaciones de la técnica, todas con buenos resultados. En este trabajo describimos en detalle la técnica quirúrgica de la ligadura endoscópica subfascial de venas perforantes que utilizamos de acuerdo a las modificaciones preconizadas por Tawes, efectuada en 20 pacientes portadores de lipodermatoesclerosis con o sin úlceras activas, pero todos con historia de ulceraciones a repetición de larga data. Los resultados de esta técnica muestran que no se presentaron complicaciones mayores como trombosis venosa profunda ni flebitis; se requirió sólo un día de hospitalización y no se observó recidiva de las ulceras en 2,5 años de seguimiento