1,238 research outputs found
OvariectomÃa laparoscópica en 20 perras
Se realiza la ovariectomÃa laparoscópica en 20 perras elegidas al azar. Se evalúa la técnica empleada asà como complicaciones a corto plazo. Se valora positivamiente el uso de instrumental bipolar para su realización
Localización del equipamiento hotelero en Leicestershire. Implicaciones en su articulación territorial
Un estudio sobre el papel de las analogÃas en la construcción del modelo cinético-molecular de la materia
En este trabajo se propone, en primer lugar, un marco teórico para analizar el papel de las analogÃas en la construcción de modelos sobre fenómenos cientÃficos por parte de los alumnos. Tomando como base dicho marco, se fundamenta, en segundo lugar, un diseño didáctico concreto encaminado a facilitar la construcción del modelo cinético-molecular de la materia a través de analogÃas, en alumnos de educación secundaria obligatoria. Finalmente, se evalúa el diseño didáctico empleado comparando los resultados finales alcanzados en pruebas de interpretación y predicción de fenómenos en un grupo experimental y en otro de control. Los resultados obtenidos parecen indicar que las analogÃas jugaron un papel relevante en la comprensión de los alumnos que fueron enseñados a través de dicho recurso. Éstos aportaron, finalmente, modelos explicativos más acordes con el modelo cientÃfico que los alumnos que fueron enseñados según un diseño semejante pero sin analogÃas, si bien las diferencias encontradas fueron pequeñas.In order to analyze the role of the analogies on the model construction about scientific phenomena in the students, a theoretical framework is firstly proposed. From this framework, a concrete didactic design is also proposed with regard to facilitating the construction of a kinetic-molecular model of matter through analogies, in students of compulsory secondary education. Finally, the didactic design used is evaluated, comparing the final results in the interpretation and prediction of phenomena between an experimental group and a control one. The post-test results indicate that the analogies used played a relevant role in the learning process of the pupils who were taught through the mentioned resource. They provided, finally, explanatory models more in agreement with the scientific model than the pupils who were taught according to a similar design but without analogies, although the differences found were small
Una propuesta didáctica basada en la investigación para el uso de analogÃas en la enseñanza de las ciencias
In this paper, an analysis about the advantages and difficulties of the analogies, as a didactic resource in science education, is accomplished. According to the results of the investigation developed in this field during the last years, some criteria to take into account with the purpose of improving their use in the classroom, are also provided. All these contributions are accompanied by concrete examples that help to illustrate the considerations and the didactic implications for educational practice
Optical coherence tomography in patients with chronic migraine: Literature review and update
Migraine is a chronic disease characterized by unilateral, pulsating, and often moderate-to-severe recurrent episodes of headache with nausea and vomiting. It affects approximately 15% of the general population, yet the underlying pathophysiological mechanisms are not fully understood. Optical coherence tomography (OCT) is a safe and reproducible diagnostic technique that utilizes infrared wavelengths and has a sensitivity of 8-10 µm. It can be used to measure thinning of the retinal nerve fiber layer (RNFL) in some neurological disorders. Although ophthalmologists are often the first specialists to examine patients with migraine, few studies have addressed the involvement of the optic nerve and retino-choroidal structures in this group. We reviewed the literature on the etiological and pathological mechanisms of migraine and the relationship between recurrent constriction of cerebral and retrobulbar vessels and ischemic damage to the optic nerve, retina, and choroid. We also assessed the role of OCT for measuring peripapillary RNFL thickness and macular and choroidal changes in migraine patients. There is considerable evidence of cerebral and retrobulbar vascular involvement in the etiology of migraine. Transitory and recurrent constriction of the retinal and ciliary arteries may cause ischemic damage to the optic nerve, retina, and choroid in patients with migraine. OCT to assess the thickness of the peripapillary RNFL, macula, and choroid might increase our understanding of the pathophysiology of migraine and facilitate diagnosis of retino-choroidal compromise and follow-up of therapy in migraine patients. Future studies should determine the usefulness of OCT findings as a biomarker of migraine
Fracturas de extremidad proximal de cubito en el niño
Las fracturas y epifisiolisis proximales de cubito, son lesiones raras y cuando se producen suelen estar mÃnimamente ó no desplazadas, pudiendo ser tratadas de forma conservadoras. En los casos en que existe desplazamiento significativo, requieren reducción abierta y osteosÃntesis. Independientemente del tipo de tratamiento utilizado, el resultado final suele ser satisfactorio. Realizamos un estudio retrospectivo de 13 casos de fractura-epifisiolisis de extremo proximal de cubito, ocurridas durante el periodo 1992-2001. Nuestro objetivo es analizar los resultados obtenidos en el tratamiento de las lesiones y realizar una revisión bibliográfica, teniendo en cuenta los distintos métodos de clasificación, valoración de resultados y las valoraciones descritas para la iniciación de tratamiento quirúrgico de estas lesiones.The epiphysiolisis and proximal lunar fractures in children rare injuries and usually the aren't displaced. In these cases they can be managed nonoperatively. If there's a marked displacement, open reduction and internal fixation is mandatory. The final outcome uses to be successful despite the management; 13 patients with epiphysiolisis or fracture of the proximal ulna between 1992-2001 ere revised. Our aim is to evaluate our outcomes and reviewed the literatur
The Northern wraps of the Sagittarius Stream as traced by Red Clump stars: distances, intrinsic widths and stellar densities
We trace the tidal Stream of the Sagittarius dwarf spheroidal galaxy (Sgr
dSph) using Red Clump stars from the catalog of the Sloan Digital Sky Survey -
Data Release 6, in the range 150{\deg} < RA < 220{\deg}, corresponding to the
range of orbital azimuth 220{\deg} < Lambda < 290{\deg}. Substructures along
the line of sight are identified as significant peaks in the differential star
count profiles (SCP) of candidate Red Clump stars. A proper modeling of the
SCPs allows us to obtain: (a) <10% accurate, purely differential distances with
respect to the main body of Sgr, (b) estimates of the FWHM along the line of
sight, and (c) estimates of the local density, for each detected substructure.
In the range 255{\deg} < Lambda < 290{\deg} we cleanly and continuously trace
various coherent structures that can be ascribed to the Stream, in particular:
the well known northern portion of the leading arm, running from d~43 kpc at
Lambda ~ 290{\deg} to d ~ 30 kpc at Lambda ~ 255{\deg}, and a more nearby
coherent series of detections lying at constant distance d ~ 25 kpc, that can
be identified with a wrap of the trailing arm. The latter structure, predicted
by several models of the disruption of Sgr dSph, was never traced before;
comparison with existing models indicates that the difference in distance
between these portions of the leading and trailing arms may provide a powerful
tool to discriminate between theoretical models assuming different shapes of
the Galactic potential. A further, more distant wrap in the same portion of the
sky is detected only along a couple of lines of sight.[abridged]Comment: 31 pages, 28 figures, accepted for publication in the Astrophysical
Journal, a version with figures at full resolution can be downloaded at the
following URL: http://www.bo.astro.it/SGR
SARS-CoV-2 congenital infection and pre-eclampsia-like syndrome in dichorionic twins: A case report and review of the literature
Although the route of transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is mainly respiratory, vertical transmission seems possible.1 We report the case of a woman with a dichorionic diamniotic twin pregnancy admitted to Hospital ClÃnico Universitario Lozano Blesa at 38+4 weeks of gestation due to severe pre-eclampsia in the context of a SARS-CoV-2 infection (positive nasopharyngeal PCR; Viasure, CerTest Biotec., Zaragoza, Spain) with a probable transplacental transmission of the virus to both twins..
Squaric acid adsorption and oxidation at gold and platinum electrodes
The adsorption and oxidation of squaric acid (3,4-dihydroxycyclobut-3-ene-1,2-dione, H2C4O4, SQA) at platinum and gold electrodes were studied spectroelectrochemically in perchloric acid solutions. Voltammetric experiments demonstrate that reversible adsorption takes place at gold electrodes in the double-layer region. As a difference with platinum electrodes, no dissociative adsorption processes leading to the blocking of the electrode surface are detected. ATR-SEIRAS experiments show potential-dependent adsorbate bands at potentials below 1.20 V vs RHE that, according to DFT calculations, can be assigned to adsorbed squarate. For platinum electrodes, the potential-dependent adsorption of squarate anions is coupled with the oxidative stripping of adsorbed carbon monoxide, which is formed upon dissociative SQA adsorption. Bonding of squarate species to the platinum and gold surfaces involves two oxygen atoms in a bidentate configuration, with the molecular plane perpendicular to the metal surface. The ATR-SEIRA spectra obtained for gold electrodes in the SQA oxidation region show bands for adsorbed bicarbonate anions formed from dissolved carbon dioxide molecules. In the case of platinum, distinct bands are observed for adsorbed oxidation products which probably are formed upon opening of the SQA ring.The authors acknowledge the funding by Ministerio de EconomÃa y Competitividad (through projects CTQ2016-76221-P (AIE/FEDER, UE) and CTQ2016-76231-C2-2-R (AEI/FEDER, UE)) and by the University of Alicante (VIGROB-263 project)
Re-Assembling the Sagittarius Dwarf Galaxy
What is the mass of the progenitor of the Sagittarius (Sgr) dwarf galaxy?
Here, we reassemble the stellar debris using SDSS and 2MASS data to find the
total luminosity and likely mass. We find that the luminosity is in the range
9.6-13.2 x10^7 solar luminosities or M_V ~ -15.1 - 15.5, with 70% of the light
residing in the debris streams. The progenitor is somewhat fainter than the
present-day Small Magellanic Cloud, and comparable in brightness to the M31
dwarf spheroidals NGC 147 and NGC 185. Using cosmologically motivated models,
we estimate that the mass of Sgr's dark matter halo prior to tidal disruption
was ~10^10 solar masses.Comment: 12 pages, 11 figures, 3 tables, submitted to Ap
- …