188 research outputs found
Factores socioeducativos que inciden en la deserción escolar en los/las estudiantes que ingresaron en el año 2012-2013 a la carrera de Ciencias Naturales del turno de profesionalización de la FAREM-ESTELÍ
La investigación: “Factores socioeducativos que inciden en la deserción escolar de los estudiantes que ingresaron en el año 2012 – 2013 a la carrera de Ciencias Naturales del turno de profesionalización en la universidad FAREM – ESTELI”, tiene como propósito principal analizar los factores socioeducativos que inciden en la deserción escolar, y proponer acciones para la mejora de la retención escolar. Con la aplicación de estos instrumentos como recurso metodológico, se logró descubrir las razones de deserción escolar de los estudiantes que ingresaron en el año 2012- 2013 a la carrera de Ciencias Naturales y que corresponde al cuarto y quinto año de la licenciatura
Factores socioeducativos que inciden en la deserción escolar de los estudiantes que ingresaron en el año 2012- 2013 a la carrera de Ciencias Naturales del turno profesionalización de la FAREM – ESTELÍ
La deserción escolar es una realidad en nuestro país así como también en los países Latino Americanos, dándose este problema desde los niveles de primaria hasta universidades. Corresponde a un problema muy sentido por el MINED así como para los docentes que laboran en diferentes colegios y universidades, a pesar de los esfuerzos realizados por diferentes instituciones para lograr la retención de los estudiantes, en nuestro país se sigue viviendo esta situación
The TRENDS High-Contrast Imaging Survey. VI. Discovery of a Mass, Age, and Metallicity Benchmark Brown Dwarf
The mass and age of substellar objects are degenerate parameters leaving the
evolutionary state of brown dwarfs ambiguous without additional information.
Theoretical models are normally used to help distinguish between old, massive
brown dwarfs and young, low mass brown dwarfs but these models have yet to be
properly calibrated. We have carried out an infrared high-contrast imaging
program with the goal of detecting substellar objects as companions to nearby
stars to help break degeneracies in inferred physical properties such as mass,
age, and composition. Rather than using imaging observations alone, our targets
are pre-selected based on the existence of dynamical accelerations informed
from years of stellar radial velocity (RV) measurements. In this paper, we
present the discovery of a rare benchmark brown dwarf orbiting the nearby
( pc), solar-type (G9V) star HD 4747 ([Fe/H]=)
with a projected separation of only AU (
0.6"). Precise Doppler measurements taken over 18 years reveal the companion's
orbit and allow us to place strong constraints on its mass using dynamics (). Relative photometry (,
, ) indicates that HD 4747 B is
most-likely a late-type L-dwarf and, if near the L/T transition, an intriguing
source for studying cloud physics, variability, and polarization. We estimate a
model-dependent mass of for an age of
Gyr based on gyrochronology. Combining astrometric measurements with RV data,
we calculate the companion dynamical mass () and orbit
() directly. As a new mass, age, and metallicity benchmark, HD
4747 B will serve as a laboratory for precision astrophysics to test
theoretical models that describe the emergent radiation of brown dwarfs.Comment: Accepted to Ap
A Comparison of Spectroscopic versus Imaging Techniques for Detecting Close Companions to Kepler Objects of Interest
(Abbreviated) Kepler planet candidates require both spectroscopic and imaging
follow-up observations to rule out false positives and detect blended stars.
[...] In this paper, we examine a sample of 11 Kepler host stars with
companions detected by two techniques -- near-infrared adaptive optics and/or
optical speckle interferometry imaging, and a new spectroscopic deblending
method. We compare the companion Teff and flux ratios (F_B/F_A, where A is the
primary and B is the companion) derived from each technique, and find no cases
where both companion parameters agree within 1sigma errors. In 3/11 cases the
companion Teff values agree within 1sigma errors, and in 2/11 cases the
companion F_B/F_A values agree within 1sigma errors. Examining each Kepler
system individually considering multiple avenues (isochrone mapping, contrast
curves, probability of being bound), we suggest two cases for which the
techniques most likely agree in their companion detections (detect the same
companion star). Overall, our results support the advantage the spectroscopic
deblending technique has for finding very close-in companions (0.02-0.05") that are not easily detectable with imaging. However, we
also specifically show how high-contrast AO and speckle imaging observations
detect companions at larger separations (0.02-0.05") that are
missed by the spectroscopic technique, provide additional information for
characterizing the companion and its potential contamination (e.g., PA,
separation, m), and cover a wider range of primary star effective
temperatures. The investigation presented here illustrates the utility of
combining the two techniques to reveal higher-order multiples in known
planet-hosting systems.Comment: Accepted to AJ. 40 pages, 12 figure
The TRENDS High-Contrast Imaging Survey. VII. Discovery of a Nearby Sirius-like White Dwarf System (HD 169889)
Monitoring the long-term radial velocity (RV) and acceleration of nearby
stars has proven an effective method for directly detecting binary and
substellar companions. Some fraction of nearby RV trend systems are expected to
be comprised of compact objects that likewise induce a systemic Doppler signal.
In this paper, we report the discovery of a white dwarf companion found to
orbit the nearby ( mas) G9 V star HD 169889.
High-contrast imaging observations using NIRC2 at Keck and LMIRCam at the LBT
uncover the (, ) companion
at an angular separation of 0.8'' (28 au). Thirteen years of precise Doppler
observations reveal a steep linear acceleration in RV time series and place a
dynamical constraint on the companion mass of . This "Sirius-like" system adds to the census of white dwarf
companions suspected to be missing in the solar neighborhood.Comment: Accepted to Ap
Effects and cost of implementing a gender-sensitive reproductive health program in Bolivia
The Integral Health Coordination Program (Programa de Coordinación en Salud Integral or PROCOSI), a network of 24 Bolivian NGOs, and the Population Council’s Frontiers in Reproductive Health (FRONTIERS) program evaluated the effects of interventions on clinic clients and their partners, and estimated the costs of incorporating a gender perspective into service delivery. Results show that sexual and reproductive health service organizations can implement action plans to change organizational policies and service delivery practices and to improve their infrastructure and equipment to make them more convenient for clients. The results further show that the intervention made modest but important changes in partner dynamics. No evidence was found that the incorporation of a gender perspective had an effect on the demand for sexual and reproductive health services. In the context of the current study, if change in unmet need is posited as the measure of success, then the question for program managers is whether this expenditure is justified to achieve the resulting changes in unmet need
Targeting polo-like kinase 1, a regulator of p53, in the treatment of adrenocortical carcinoma
60 Validated Planets from K2 Campaigns 5-8
We present a uniform analysis of 155 candidates from the second year of
NASA's mission (Campaigns 5-8), yielding 60 statistically validated
planets spanning a range of properties, with median values of = 2.5
, = 7.1 d, = 811 K, and = 11.3 mag. The
sample includes 24 planets in 11 multi-planetary systems, as well as 18 false
positives, and 77 remaining planet candidates. Of particular interest are 18
planets smaller than 2 , five orbiting stars brighter than = 10
mag, and a system of four small planets orbiting the solar-type star EPIC
212157262. We compute planetary transit parameters and false positive
probabilities using a robust statistical framework and present a complete
analysis incorporating the results of an intensive campaign of high resolution
imaging and spectroscopic observations. This work brings the yield to over
360 planets, and by extrapolation we expect that will have discovered
600 planets before the expected depletion of its on-board fuel in late
2018.Comment: 33 pages, 13 figures, 5 tables, accepted for publication in A
The TRENDS High-contrast Imaging Survey. VIII. Compendium of Benchmark Objects
The physical properties of faint stellar and substellar objects often rely on indirect, model-dependent estimates. For example, the masses of brown dwarfs are usually inferred using evolutionary models, which are age dependent and have yet to be properly calibrated. With the goal of identifying new benchmark objects to test low-mass stellar and substellar models, we have carried out a comprehensive adaptive optics survey as part of the TaRgetting bENchmark-objects with the Doppler Spectroscopy high-contrast imaging program. Using legacy radial velocity measurements from the High Resolution Echelle Spectrometer at Keck, we have identified several dozen stars that show long-term Doppler accelerations. We present follow-up high-contrast observations from the campaign and report the discovery of 31 comoving companions, as well as 11 strong candidate companions, to solar-type stars with well-determined parallax and metallicity values. Benchmark objects of this nature lend themselves to orbit determinations, dynamical mass estimates, and independent compositional assessment. This compendium of benchmark objects will serve as a convenient test group to substantiate theoretical evolutionary and atmospheric models near the hydrogen fusing limit
The TRENDS High-contrast Imaging Survey. VIII. Compendium of Benchmark Objects
The physical properties of faint stellar and substellar objects often rely on indirect, model-dependent estimates. For example, the masses of brown dwarfs are usually inferred using evolutionary models, which are age dependent and have yet to be properly calibrated. With the goal of identifying new benchmark objects to test low-mass stellar and substellar models, we have carried out a comprehensive adaptive optics survey as part of the TaRgetting bENchmark-objects with the Doppler Spectroscopy high-contrast imaging program. Using legacy radial velocity measurements from the High Resolution Echelle Spectrometer at Keck, we have identified several dozen stars that show long-term Doppler accelerations. We present follow-up high-contrast observations from the campaign and report the discovery of 31 comoving companions, as well as 11 strong candidate companions, to solar-type stars with well-determined parallax and metallicity values. Benchmark objects of this nature lend themselves to orbit determinations, dynamical mass estimates, and independent compositional assessment. This compendium of benchmark objects will serve as a convenient test group to substantiate theoretical evolutionary and atmospheric models near the hydrogen fusing limit
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