Vortex ratchet reversal at fractional matching fields in kagom\'e-like array with symmetric pinning centers

Arrays of Ni nanodots embedded in Nb superconducting films have been fabricated by sputtering and electron beam lithography techniques. The arrays are periodic triangular lattices of circular Ni dots arranged in a kagom\'e-like pattern with broken reflection symmetry. Relevant behaviors are found in the vortex lattice dynamics : i) At values lower than the first integer matching field, several fractional matching fields are present when the vortex lattice moves parallel or perpendicular to the reflection symmetry axis of the array showing a clear anisotropic character in the magnetoresistance curves, ii) injecting an ac current perpendicular to the reflection symmetry axis of the array yields an unidirectional motion of the vortex lattice (ratchet effect) as a result of the interaction between the whole vortex lattice and the asymmetric lattice of dots, iii) increasing the input current amplitudes the ratchet effect changes polarity independently of matching field values. These experimental results can be explained taking into account the vortex lattice density.Comment: 9 pages, 4 figures, 1 tabl

Enfermedades neuropediátricas afectan el desarrollo escolar de niños bogotanos

Los niños y jóvenes de los colegios de Bogotá, principalmente en los estratos socioeconómicos más bajos, están registrando una gran prevalencia de problemas del neurodesarrollo y del aprendizaje, lo cual incide negativamente en su desempeño escolar. A esta conclusión llegó el Grupo de Investigación en Neurociencias (Neuros) de la Facultad de Medicina de la Universidad del Rosario, el cual evaluó la prevalencia de las enfermedades neuropediátricas dentro de las que se incluyen los trastornos de aprendizaje, neurodesarrollo y atención, entre otros, en la población infantil de 5 a 12 años de algunos colegios de primaria en las localidades de Barrios Unidos, Bosa, Ciudad Bolívar, Engativá y Usme. Según Alberto Vélez van Meerbeke, miembro del grupo de investigación, aunque la epilepsia y otras enfermedades neurológicas no tienen una prevalencia elevada, la carga de esta enfermedad es importante por cuanto son enfermedades crónicas que pueden por sí solas afectar el desarrollo social, psicológico e intelectual de las personas. En general, afirma Vélez, los niños estudiados no recibían un tratamiento para el problema diagnosticado, debido a que los colegios no están capacitados para atender a los niños con problemas del aprendizaje o no tienen un equipo terapéutico que los apoye. Sólo en colegios privados se encontraron equipos capacitados para esta labor, pero los padres de los niños de estratos más bajos no tienen los recursos para ingresar a dichas instituciones. Incluso, cuando los niños son enviados a la consulta médica, el personal de salud no conoce la problemática y por lo tanto los pacientes se quedan sin la posibilidad de un manejo adecuado. Es decir, que al no ser intervenidos, apoyados y estimulados, continuarán enfrentados a un fracaso continuo con problemas subsiguientes de tipo adaptativo y social. Según Claudia Talero Gutiérrez, investigadora del grupo Neuros, esta cadena lleva a que, en una sociedad que es cada vez más exigente, las expectativas laborales de estos niños al llegar a la vida adulta no vayan más allá de trabajos poco calificados, mal remunerados, inestables y con marginalidad, por lo cual se hace necesario que los niños con dificultades tengan un seguimiento y manejo apropiado de profesionales de la salud, familiares y educadores para garantizar un rendimiento escolar exitoso

Directional vortex motion guided by artificially induced mesoscopic potentials

Rectangular pinning arrays of Ni dots define a potential landscape for vortex motion in Nb films. Magnetotransport experiments in which two in-plane orthogonal electrical currents are injected simultaneously allow selecting the direction and magnitude of the Lorentz force on the vortex-lattice, thus providing the angular dependence of the vortex motion. The background dissipation depends on angle at low magnetic fields, which is progressively smeared out with increasing field. The periodic potential locks in the vortex motion along channeling directions. Because of this, vortex-lattice direction of motion is up to 85o away from the applied Lorentz force direction.Comment: PDF file includes figure

Preferences, use of and satisfaction with mental health services among a sample of Puerto Rican cancer patients

OBJECTIVE: The purpose of this study was to describe the preferences, the use, satisfaction of mental health services (MHS) among a sample of Puerto Rican patients with cancer undergoing oncology treatment. METHODS: A convenience sample of 120 patients diagnosed with cancer was recruited. Self-report questionnaires assessed socio-demographic and background questions, and the Mental Health Service Preference, Utilization and Satisfaction Questionnaire (MHSPUS). The Socio-demographic and Background Questionnaire inquired about participants\u27 demographic and socioeconomic characteristics, and included questions such as history of psychiatric diagnosis and spiritual practices. Univariate and Chi square analyses were used for descriptive purposes. Logistic regressions were used to explore associations between sociodemographic factors and MHS preferences and use. RESULTS: The majority of the sample were females (53.8%), 61 and older (53.8%), and married or living with partner (57.1%), and reported an income equal to or less than $12,000 per year (44.4%), which places them under the US federal poverty line. Most of the participants (66.7%) reported being receptive to seeking services. Findings showed a significant association between living situation and past (p \u3c .05) and lifetime use (p \u3c .05) of MHS and past use of MHS. Participants living alone were more like to have used MHS in the past and during their lifetime. Adjusted logistic regression analyses revealed that living with someone was a protective factor for not using MHS in their lifetime (OR = 0.28; C1 = 0.08-0.95). Participants preferred to receive MHS at the oncology clinic, preferably on the date of their oncology appointments and during morning hours. CONCLUSION: Findings support the integration of mental health services within the oncology practice setting

Long-term assessment of the translocation of an endangered primate into an agroforestry system

Translocation is increasingly being used as a conservation tool in wildlife management, but long-term assessments of the animals’ establishment in the new habitat are rarely done. In addition, finding protected areas for translocations can often be a limitation, but habitat patches managed for productive purposes could potentially be used for translocations. Here, we present a translocation case study of the Endangered Mexican howler monkey Alouatta palliata mexicana into a forest fragment managed as an agroforest in the Los Tuxtlas Biosphere Reserve (Mexico). We compared the behavior of the translocated focal group 6 yr after translocation with that ob - served 1 yr after translocation (Year 1 vs. Year 6), and with reference parameters for conserved forest. We also examined the 14 yr trajectory of the translocated population through published data. We found that in Year 6, monkeys spent less time on locomotion and more time consuming fruit than in Year 1. The focal group in Year 6 had doubled its activity area compared to Year 1. All behavioral parameters during Year 6 were similar to those reported for the species in conserved forest. During the first 14 yr, the translocated population increased at a rate of 1.29 ind. yr−1. We conclude that this translocation succeeded in establishing a thriving population and that certain agroforestry systems may be adequate habitat for primate translocations. We also discuss how the translocation of howler monkeys into defaunated habitats might help restore ecological functions associated with these primates, such as the dispersal of large-seeded plants. Long-term information on successful primate translocations has high practical value for designing adequate conservation strategies in anthropogenic landscapes

Magnetic order and disorder in nanomagnets probed by superconducting vortices

We have studied two nanomagnet systems with strong (Co/Pd multilayers) and weak (NdCo alloy films) stray magnetic fields by probing the out-of-plane magnetic states with superconducting vortices. The hybrid samples are made of array of nanomagnets embedded in superconducting Nb thin films. The vortex motion detects relevant magnetic state features, since superconducting vortices are able to discriminate between different magnetic stray field strengths and directions. The usual matching effect between the superconducting vortex lattice and the periodic pinning array can be quenched by means of disorder magnetic potentials with strong stray fields at random. Ordered stray fields retrieve the matching effect and yield asymmetry and shift in the vortex dissipation signal. Furthermore vortices can discriminate the sizes of the nanomagnet magnetic domains, detecting magnetic domain sizes as small as 70 nm. In addition, we observe that the vortex cores play the crucial role instead of the supercurrents around the vortex.Comment: 22 pages, 8 figure

Acute Postoperative Infectious Endophthalmitis: Advances in Diagnosis and Treatment

Acute postoperative infectious endophthalmitis remains one of the most dreaded complications of ophthalmic surgery. One of the keys to success in treating this complication is to make an early clinical diagnosis and, if possible, an etiologic diagnosis that can guide treatment with antibiotic therapy. Different antibiotic therapy modalities have emerged over the years that have made it possible to treat even resistant strains of various microorganisms that cause endophthalmitis. Another relevant advance made in the etiological diagnosis of endophthalmitis is the advent of molecular biology techniques, such as the real-time polymerase chain reaction, which can detect minimal amounts of the genetic material of the causative microorganism present in the vitreous in a short period of time, thus improving treatment outcomes with better-guided therapy with intravitreal antibiotics. Aside from advances in postoperative diagnosis methods, the surgical treatment of endophthalmitis has had significant improvements in vitrectomy techniques, and in many cases, it has been proposed as the first-line treatment concomitantly with intravitreal antibiotic therapy. Moreover, there is increasing evidence that prophylaxis with intracameral antibiotic therapy further decreases postoperative endophthalmitis incidence

The 2HWC HAWC Observatory Gamma Ray Catalog

We present the first catalog of TeV gamma-ray sources realized with the recently completed High Altitude Water Cherenkov Observatory (HAWC). It is the most sensitive wide field-of-view TeV telescope currently in operation, with a 1-year survey sensitivity of ~5-10% of the flux of the Crab Nebula. With an instantaneous field of view >1.5 sr and >90% duty cycle, it continuously surveys and monitors the sky for gamma ray energies between hundreds GeV and tens of TeV. HAWC is located in Mexico at a latitude of 19 degree North and was completed in March 2015. Here, we present the 2HWC catalog, which is the result of the first source search realized with the complete HAWC detector. Realized with 507 days of data and represents the most sensitive TeV survey to date for such a large fraction of the sky. A total of 39 sources were detected, with an expected contamination of 0.5 due to background fluctuation. Out of these sources, 16 are more than one degree away from any previously reported TeV source. The source list, including the position measurement, spectrum measurement, and uncertainties, is reported. Seven of the detected sources may be associated with pulsar wind nebulae, two with supernova remnants, two with blazars, and the remaining 23 have no firm identification yet.Comment: Submitted 2017/02/09 to the Astrophysical Journa

The Sensitivity of HAWC to High-Mass Dark Matter Annihilations

The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in central Mexico at 19 degrees North latitude and 4100 m above sea level, HAWC will observe gamma rays and cosmic rays with an array of water Cherenkov detectors. The full HAWC array is scheduled to be operational in Spring 2015. In this paper, we study the HAWC sensitivity to the gamma-ray signatures of high-mass (multi- TeV) dark matter annihilation. The HAWC observatory will be sensitive to diverse searches for dark matter annihilation, including annihilation from extended dark matter sources, the diffuse gamma-ray emission from dark matter annihilation, and gamma-ray emission from non-luminous dark matter subhalos. Here we consider the HAWC sensitivity to a subset of these sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the Galactic center. We simulate the HAWC response to gamma rays from these sources in several well-motivated dark matter annihilation channels. If no gamma-ray excess is observed, we show the limits HAWC can place on the dark matter cross-section from these sources. In particular, in the case of dark matter annihilation into gauge bosons, HAWC will be able to detect a narrow range of dark matter masses to cross-sections below thermal. HAWC should also be sensitive to non-thermal cross-sections for masses up to nearly 1000 TeV. The constraints placed by HAWC on the dark matter cross-section from known sources should be competitive with current limits in the mass range where HAWC has similar sensitivity. HAWC can additionally explore higher dark matter masses than are currently constrained.Comment: 15 pages, 4 figures, version to be published in PR