Motivación al Logro en Procesos de Aprendizaje

El objetivo del artículo es analizar los efectos de la motivación al logro en los procesos de aprendizaje a nivel de educación, para esto se desarrolló una exhaustiva revisión bibliográfica en función de conocer los diversos aportes de autores sobre el tema motivacional y su impacto en el rendimiento académico de los estudiantes. Este tema resulta relevante en el entendido de los retos que plantea la educación actual en el contexto de los factores que distraen la atención de las personas y mucho más de los adolescentes. En tal sentido se presentan unas consideraciones sobre la motivación y sus implicaciones emocionales sobre las personas, esta motivación no solo se debe promover en los educandos, sino que debe partir de la propia conducta emocional y la motivación personal del docente, el cual debe desde sus actos pedagógicos irradiar toda una conducta que demuestre mediante el desarrollo de su trabajo de aula sus intereses por la consecución de los propósitos y el logro de las metas de los estudiantes

Enhanced fluctuations of the tunneling density of states near bottoms of Landau bands measured by a local spectrometer

We have found that the local density of states fluctuations (LDOSF) in a disordered metal, detected using an impurity in the barrier as a spectrometer, undergo enhanced (with respect to SdH and dHvA effects) oscillations in strong magnetic fields, omega _c\tau > 1. We attribute this to the dominant role of the states near bottoms of Landau bands which give the major contribution to the LDOSF and are most strongly affected by disorder. We also demonstrate that in intermediate fields the LDOSF increase with B in accordance with the results obtained in the diffusion approximation.Comment: 4 pages, 4 figure

Theory of Banana Liquid Crystal Phases and Phase Transitions

We study phases and phase transitions that can take place in the newly discovered banana (bow-shaped or bent-core) liquid crystal molecules. We show that to completely characterize phases exhibited by such bent-core molecules a third-rank tensor $T^{ijk}$ order parameter is necessary in addition to the vector and the nematic (second-rank) tensor order parameters. We present an exhaustive list of possible liquid phases, characterizing them by their space-symmetry group and order parameters, and catalog the universality classes of the corresponding phase transitions that we expect to take place in such bent-core molecular liquid crystals. In addition to the conventional liquid-crystal phases such as the nematic phase, we predict the existence of novel liquid phases, including the spontaneously chiral nematic $(N_T + 2)^*$ and chiral polar $(V_T + 2)^*$ phases, the orientationally-ordered but optically isotropic tetrahedratic $T$ phase, and a novel nematic $N_T$ phase with $D_{2d}$ symmetry that is neither uniaxial nor biaxial. Interestingly, the Isotropic-Tetrahedratic transition is {\em continuous} in mean-field theory, but is likely driven first-order by thermal fluctuations. We conclude with a discussion of smectic analogs of these phases and their experimental signatures.Comment: 28 pgs. RevTex, 32 eps figures, submitted to Phys. Rev.

Enhanced Fluctuations of the Tunneling Density of States near the Bottom of a Landau Band Measured by a Local Spectrometer

We have found that the local density of state fluctuations (LDOSF) in a disordered metal, detected using an impurity in the barrier as a spectrometer, undergo enhanced (with respect to Shubnikov -de Haas and de Haas -van Alphen effects) oscillations in strong magnetic fields, v c t 1. We attribute this to the dominant role of the states near the bottom of Landau bands which give the major contribution to the LDOSF and are most strongly affected by disorder. We also demonstrate that in intermediate fields the LDOSF increase with field B in accordance with the results obtained in the diffusion approximation. PACS numbers: 73.23.Hk, 72.15.Gd, 73.20.Fz, 73.40.Ty Resonant tunneling through individual impurities has been identified and studied in vertical In this paper, we study the evolution with magnetic field of the LDOSF in a 3D disordered metal, a heavily doped semiconductor, and discuss the results from the point of view of the fluctuation and correlation properties of single-particle wave functions in disordered media. We have measured the fingerprint of the LDOSF, dn͑´͒, in the differential conductance G͑V ͒ dI dV ͑V ͒ in a broad range of magnetic fields, B, and analyzed its variance, ͗dG 2 ͘, and correlation parameters. In intermediate fields, v c t ϳ 1, we have detected an increase of the fluctuation magnitude, in agreement with the theoretically predicted behavior [11]: ͗͑dG͒ 2 ͘ B ͗͑͞dG͒ 2 ͘ B0 ഠ 1 1 ͑v c t͒ 2 . At higher fields, v c t 1, we have observed large 1͞B periodic oscillations in ͗dG 2 ͘. We conclude that LDOSF in strong fields are dominated by the states near the minimum of the Landau bands which play a distinguished role relative to the rest of the spectrum. Notably, the observed oscillations are significantly stronger than those in other oscillatory effects in metals, such as de Haas-van Alphen effect. The investigated structure consists of a 50 Å GaAs well imbedded between two 81 Å Al 0.33 Ga 0.67 As barriers. Each Si-doped GaAs contact consists of three layers: 4800 Å with nominal doping 10 18 cm 23 is followed by 4800 Å with 2 3 10 17 cm 23 , and the latter is separated from the barrier by an undoped spacer of 300 Å and 200 Å, for top and bottom contact, respectively. The lateral area of the nominally undoped quantum well is reduced to a 700 Å diameter disk using the ion bombardment technique At zero bias, the spectrometer level S is above the Fermi level m of the emitter with 3D metallic conduction. The alignment of S and m with increasing bias is registered as a step in IV . In the differential conductance G͑V ͒ shown in and its width is related to the energetic width of the spectrometer G Ӎ G max Ӎ 120 meV determined by the tunneling coupling between the impurity and the contacts. The values of G min,max depend on the transparencies of the two barriers, so that G max corresponds to the lower (collector) barrier and G min corresponds to the higher (emitter) barrier, G min ϳ 5 3 10 23 G max , as estimated from the value of G G . The relation between bias V and the energy scale of the spectrometer is established by the coefficientf b dE d͑eV ͒ 0.24, found for the selected 0031-9007͞00͞84(7)͞1563(4)$15.0

Response to treatment in a prospective cohort of patients with large ulcerated lesions suspected to be Buruli Ulcer (Mycobacterium ulcerans disease)

BACKGROUND: The World Health Organization (WHO) advises treatment of Mycobacterium ulcerans disease, also called "Buruli ulcer" (BU), with a combination of the antibiotics rifampicin and streptomycin (R+S), whether followed by surgery or not. In endemic areas, a clinical case definition is recommended. We evaluated the effectiveness of this strategy in a series of patients with large ulcers of > or =10 cm in longest diameter in a rural health zone of the Democratic Republic of Congo (DRC). METHODS: A cohort of 92 patients with large ulcerated lesions suspected to be BU was enrolled between October 2006 and September 2007 and treated according to WHO recommendations. The following microbiologic data were obtained: Ziehl-Neelsen (ZN) stained smear, culture and PCR. Histopathology was performed on a sub-sample. Directly observed treatment with R+S was administered daily for 12 weeks and surgery was performed after 4 weeks. Patients were followed up for two years after treatment. FINDINGS: Out of 92 treated patients, 61 tested positive for M. ulcerans by PCR. PCR negative patients had better clinical improvement than PCR positive patients after 4 weeks of antibiotics (54.8% versus 14.8%). For PCR positive patients, the outcome after 4 weeks of antibiotic treatment was related to the ZN positivity at the start. Deterioration of the ulcers was observed in 87.8% (36/41) of the ZN positive and in 12.2% (5/41) of the ZN negative patients. Deterioration due to paradoxical reaction seemed unlikely. After surgery and an additional 8 weeks of antibiotics, 98.4% of PCR positive patients and 83.3% of PCR negative patients were considered cured. The overall recurrence rate was very low (1.1%). INTERPRETATION: Positive predictive value of the WHO clinical case definition was low. Low relapse rate confirms the efficacy of antibiotics. However, the need for and the best time for surgery for large Buruli ulcers requires clarification. We recommend confirmation by ZN stain at the rural health centers, since surgical intervention without delay may be necessary on the ZN positive cases to avoid progression of the disease. PCR negative patients were most likely not BU cases. Correct diagnosis and specific management of these non-BU ulcers cases are urgently needed.This study was supported by the Directorate-General for Development and Cooperation (DGDC), Brussels, Belgium, the European Commission (International Science and Technology Cooperation Development Program) (project no. INCO-CT-2005-051476-BURULICO), and by a grant from the Health Services of Fundacao Calouste Gulbenkian. K.K. was supported by a grant from DGDC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Clinical reporting following the quantification of cerebrospinal fluid biomarkers in Alzheimer's disease: An international overview

Introduction: The current practice of quantifying cerebrospinal fluid (CSF) biomarkers as an aid in the diagnosis of Alzheimer's disease (AD) varies from center to center. For a same biochemical profile, interpretation and reporting of results may differ, which can lead to misunderstandings and raises questions about the commutability of tests. Methods: We obtained a description of (pre-)analytical protocols and sample reports from 40 centers worldwide. A consensus approach allowed us to propose harmonized comments corresponding to the different CSF biomarker profiles observed in patients. Results: The (pre-)analytical procedures were similar between centers. There was considerable heterogeneity in cutoff definitions and report comments. We therefore identified and selected by consensus the most accurate and informative comments regarding the interpretation of CSF biomarkers in the context of AD diagnosis. Discussion: This is the first time that harmonized reports are proposed across worldwide specialized laboratories involved in the biochemical diagnosis of AD