629 research outputs found
El tratamiento de problemas matemáticos interdisciplinarios en la formación del técnico medio en Agronomía
En la Educación Técnica Profesional se realizan cambios transcendentales en la formación de un técnico medio en Agronomía más competente en correspondencia con las demandas económicas del país; se considera que para el éxito en esta labor se debe tener presente el principio de la interdisciplinariedad como método de trabajo para docentes y estudiantes. En este artículo se proponen orientaciones metodológicas para el tratamiento de problemas matemáticos interdisciplinarios en la formación del técnico medio en Agronomía
Effects of basic infrastructure on ENLACE Test of High School Technology Mexican
Bajo la teoría de capital humano, la educación se concibe como auspiciadora de capital humano y económico. La inversión en capital humano puede reflejarse a mediano plazo en el logro académico de los estudiantes. El logro académico es un indicador de la eficacia de las políticas educativas, sin embargo, en Latino América hay pocos estudios que analicen los efectos que tienen los insumos o el gasto de inversión en el desempeño de los estudiantes. En el presente estudio se analizó una muestra de 538 escuelas de educación media superior con el fin de evaluar los efectos que tiene el número de alumnos por grupo y el número de alumnos por clase sobre el logro académico. Se realizó análisis factorial confirmatorio y un modelo estandarizado con análisis de senderos por Máxima Verosimilitud para infraestructura y logro académico. Se encontró que el incremento de alumnos por grupo y el número de alumnos por clase aumenta la cantidad de alumnos que obtienen niveles de ejecución elemental tanto en habilidad lectora como en habilidad matemática. Así también, disminuye el número de alumnos con desempeño excelente en ambas habilidades. Estos resultados respaldan la evidencia que indica que la infraestructura escolar afecta el desempeño o logro educativo.Under human capital theory, education is seen as sponsor of human and economic capital. Investment in human capital in the medium term may be reflected in the students' academic achievement. Academic achievement is an indicator of the effectiveness of education policies, however, in Latin America there are few studies analyzing effects of inputs or investment spending on student performance. In this study were considered 538 high schools (vocational School) in order to assess effects of number of students per classroom and number of students per class in academic achievement. We carry out a confirmatory factorial analysis and a structural model by Maximum-likelihood Paths for infrastructure and academic achievement. Was found that increase of students per classroom and per class have negative effects because these increase on quantity of students with low levels on reading and mathematical abilities. Also, was reducing the number of students with excellent performance in both skills. These results support the evidence that scholar infrastructure has effects on academic achievement
Fog interception by Ball moss (<i>Tillandsia recurvata</i>)
Interception losses are a major influence in the water yield of vegetated areas. For most storms, rain interception results in less water reaching the ground. However, fog interception can increase the overall water storage capacity of the vegetation and once the storage is exceeded, fog drip is a common hydrological input. Fog interception is disregarded in water budgets of semiarid regions, but for some plant communities, it could be a mechanism offsetting evaporation losses. <i>Tillandsia recurvata</i> is a cosmopolitan epiphyte adapted to arid habitats where fog may be an important water source. Therefore, the interception storage capacity by <i>T. recurvata</i> was measured in controlled conditions and applying simulated rain or fog. Juvenile, vegetative specimens were used to determine the potential upperbound storage capacities. The storage capacity was proportional to dry weight mass. Interception storage capacity (<i>C</i><sub>min</sub>) was 0.19 and 0.56 mm for rainfall and fog respectively. The coefficients obtained in the laboratory were used together with biomass measurements for <i>T. recurvata</i> in a xeric scrub to calculate the depth of water intercepted by rain. <i>T. recurvata</i> contributed 20 % to the rain interception capacity of their shrub hosts: <i>Acacia farnesiana</i> and <i>Prosopis laevigata</i> and; also potentially intercepted 4.8 % of the annual rainfall. Nocturnal stomatic opening in <i>T. recurvata</i> is not only relevant for CO<sub>2</sub> but for water vapor, as suggested by the higher weight change of specimens wetted with fog for 1 h at dark in comparison to those wetted during daylight (543 ± 77 vs. 325 ± 56 mg, <i>p</i> = 0.048). The storage capacity of <i>T. recurvata</i> leaf surfaces could increase the amount of water available for evaporation, but as this species colonise montane forests, the effect could be negative on water recharge, because potential storage capacity is very high, in the laboratory experiments it took up to 12 h at a rate of 0.26 l h<sup>−1</sup> to reach saturation conditions when fog was applied
Reasons for using and efficacy of raltegravir in salvage regimens without protease inhibitors in clinical practice
Relationship between Serum Concentration of Uric Acid and Insulin Secretion among Adults with Type 2 Diabetes Mellitus
To determine the relationship between serum concentrations of uric acid and insulin secretion with hyperglycaemic clamp technique among adults with type 2 diabetes mellitus (DM2) without hyperuricemia, we carried out a cross-sectional study on 45 patients of both gender. We observed correlation between uric acid with male gender r = 0.710 (P = 0.001). Also correlation between uric acid and total insulin secretion was positive r = 0.295 (P = 0.049). As well as a positive correlation adjusted for body mass index was demonstrated for the first, second, and total phases of insulin secretion, respectively, r = 0.438 (P = 0.022), r = 0.433 (P = 0.022), and r = 0.439 (P = 0.024). Serum concentration of uric acid showed a positive relationship with the total phase of insulin secretion; even in states prior to hyperuricemia, uric acid can play an important role in the function of the beta cell in patients with DM2
Facile synthesis of low band gap ZnO Microstructures
Abstract In this work a simple chemical route was employed to synthesize ZnO microparticles by precipitation from aqueous solution of ZnCl2 as precursor, NaOH as oxidizing and sodium dodecyl sulfate (SDS) as surfactant. Samples of ZnO microparticles were analyzed by scanning electron microscopy (SEM), FTIR spectroscopy, Raman spectroscopy, X-Ray diffraction, UV/Vis-NIR diffusereflectance,highresolutiontransmissionelectronmicroscopy(HR-TEM),andN2 adsorption-desorption.Itwasobserved from SEM analysis that ZnO microparticles with morphologies resembling six-blade impeller with diameters in the range of 500 nm to 1 m, and sheet-like (approximately 200 nm×300 nm) were obtained through this technique. X-Ray diffraction and Raman analyses confirmed the obtaining of hexagonal wurtzite ZnO crystal structure. The calculated band gap energy was 3.19 eV, which is slightly lower than the average value reported in the literature. Specific BET area of ZnO microparticles was 26.5 m2/g. Keywords: ZnO, microstructures, band gap energy, SEM, morphology.
Resumen En este trabajo se empleó un a ruta química sencilla para sintetizar micropartículas de ZnO mediante precipitación en solución acuosa de ZnCl2 como precursor, NaOH como oxidante y dodecil sulfato de sodio (SDS) como tensoactivo. Las muestras de ZnO fueron analizadas mediante microscopía de barrido electrónico (SEM), espectroscopía de FTIR, espectroscopía Raman, difracción de rayos-X, reflectancia difusa de UV/Vis-NIR, microscopía de transmisión de electrones de alta resolución (HRTEM), y mediante adsorción-desorción de N2. Se observó mediante análisis de SEM que mediante esta técnica se obtienen micropartículas de ZnO con morfologías similares a impulsores de seis-aspas con diámetros entre 500 nm y 1 m, morfologías tipo-hojas(deaproximadamente200nm×300nm).Losanálisisdedifracciónderayos-XydeRamanconfirmaronlaobtención de ZnO con estructura cristalina wurtzita hexagonal. La energía de band gap calculada fue de 3.19 eV, la cual es ligeramente menor que el valor promedio reportado en la literatura. El área superficial BET de las nanopartículas de ZnO fue de 26.5 m2/g Palabras clave: ZnO, microestructuras, energía de band gap, SEM, morfología
TNF-α and IL-10 downregulation and marked oxidative stress in Neuromyelitis Optica
<p>Abstract</p> <p>Background</p> <p>Neuromyelitis optica is a central nervous system demyelinating and inflammatory syndrome. The objective of this study is to identify cytokines related to the cellular immune response as well as blood brain barrier integrity and oxidative stress.</p> <p>Methods</p> <p>We performed a molecular characterization of cellular immune response and oxidative stress in serum from relapsing-NMO (R-NMO) patients and established the correlations between the clinical measurements and molecular parameters using the Bayesian approach.</p> <p>Serum samples from 11 patients with R-NMO diagnosed according to Wingerchuk criteria and matched in terms of age, gender and ethnicity with the healthy controls were analyzed. The levels of TNF-<it>α</it>, IFN-<it>γ</it>, IL-10, MMP-9, TIMP-1 and oxidative stress markers: malondialdehyde, advanced oxidation protein products, peroxidation potential, superoxide dismutase, catalase, and total hydroperoxides were measured.</p> <p>Results</p> <p>We found almost undetectable levels of TNF-<it>α</it>, a decreased production of IL-10 and a significant up-regulation of every oxidative stress biomarker studied. The insufficient production of TNF-<it>α </it>and IL-10 in R-NMO patients, which are two important players of T cell mediated immunoregulation, suggest an effector – regulator imbalance. The overproduction of oxygen reactive species as a consequence of the chronic inflammatory milieu is reflected on the excess of oxidative damage mediators detected. Furthermore, Multidimensional Scaling and a Bayesian linear regression model revealed a significant linear dependence between Expanded Disability Status Scale Kurtzke and TIMP-1; pointing to a possible predictive or prognostic value of this clinical-molecular relationship.</p> <p>Conclusion</p> <p>These results suggest that there is a breakdown in immunoregulatory mechanisms and noteworthy pro-oxidant environment contributing to NMO pathogenesis.</p
Impact of the COVID-19 Pandemic on a Cancer Fast-Track Programme
Introduction: The COVID-19 pandemic has disrupted many aspects of clinical practice in oncology, particularly regarding early cancer diagnosis, sparking public health concerns that possible delays could increase the proportion of patients diagnosed at advanced stages. In 2009, a cancer fast-track program (CFP) was implemented at the Clinico-Malvarrosa Health Department in Valencia, Spain with the aim of shortening waiting times between suspected cancer symptoms, diagnosis and therapy initiation. Objectives: The study aimed to explore the effects of the COVID-19 pandemic on our cancer diagnosis fast-track program. Methods: The program workflow (patients included and time periods) was analysed from the beginning of the state of alarm on March 16th, 2020 until March 15th, 2021. Data was compared with data from the same period of time from the year before (2019). Results: During the pandemic year, 975 suspected cancer cases were submitted to the CFP. The number of submissions only decreased during times of highest COVID-19 incidence and stricter lockdown, and overall, referrals were slightly higher than in the previous 2 years. Cancer diagnosis was confirmed in 197 (24.1%) cases, among which 33% were urological, 23% breast, 16% gastrointestinal and 9% lung cancer. The median time from referral to specialist appointment was 13 days and diagnosis was reached at a median of 18 days. In confirmed cancer cases, treatment was started at around 30 days from time of diagnosis. In total, 61% of cancer disease was detected at early stage, 20% at locally advanced stage, and 19% at advanced stage, displaying time frames and case proportions similar to pre-pandemic years. Conclusions: Our program has been able to maintain normal flow and efficacy despite the challenges of the current pandemic, and has proven a reliable tool to help primary care physicians referring suspected cancer patients.S
- …