Predictive Model of Student Dropout Based on Logistic Regression

Student desertion is a phenomenon that has spread significantly in many higher education institutions in Ecuador. The objective of the research was to develop a predictive model of student dropout based on multiple binary logistic regression, with the purpose of detecting possible dropouts. The methodology used consists of three phases: Phase 1: Analysis of variables; Phase 2: Formulation of the mathematical model; and Phase 3: Evaluation. For the estimation of the coefficients of the model, the SPSS tool was obtained. After the creation of the predictive model, it was concluded that the most significant variables that contribute to the diagnosis of dropout are marital status, age, gender, Note2s, and Note1s. It is also evident that students have a higher risk of dropping out if they are married and lower risk if they are single or divorced. Finally it was concluded that gender is a factor that directly influences dropout; male students are more likely to drop out than females. Keywords: logistic regression, predictive model, desertion. Resumen La deserción estudiantil es un fenómeno que se ha extendido significativamente en gran cantidad de instituciones educativas de nivel superior en el Ecuador. El objetivo de la investigación fue desarrollar un modelo predictivo de deserción estudiantil basado en la regresión logística binaria múltiple, con el propósito de detectar a posibles desertores. La metodología utilizada consta de tres fases: Fase1: Análisis de variables. Fase2: Formulación del modelo matemático. Fase3: Evaluación. Para la estimación de los coeficientes del modelo se utilizó la herramienta SPSS. Posterior a la creación del modelo predictivo se llegó a concluir que las variables más significativas que aportan al diagnóstico de la deserción son estado civil, edad, género Nota2s y Nota1s, además se evidencia que los estudiantes tienen mayor riesgo de deserción si están casados y menor riesgo si están solteros o divorciados, finalmente se concluye, que el género es un factor que influye directamente en la deserción, los estudiantes masculinos son más propensos a desertar que los femeninos. Palabras Clave: regresión logística, modelo predictivo, deserción

Oscillons in dilaton-scalar theories

It is shown by both analytical methods and numerical simulations that extremely long living spherically symmetric oscillons appear in virtually any real scalar field theory coupled to a massless dilaton (DS theories). In fact such "dilatonic" oscillons are already present in the simplest non-trivial DS theory -- a free massive scalar field coupled to the dilaton. It is shown that in analogy to the previously considered cases with a single nonlinear scalar field, in DS theories there are also time periodic quasibreathers (QB) associated to small amplitude oscillons. Exploiting the QB picture the radiation law of the small amplitude dilatonic oscillons is determined analytically.Comment: extended discussion on stability, to appear in JHEP, 29 pages, 7 figure

Natural abundance of stable nitrogen isotopes reflect changes in pelagic food webs and mobility of size classes of the north Iberian sardine (Sardina pilchardus)

The natural abundance of stable nitrogen isotopes (δ15N) in sardine (Sardina pilchardus) and plankton was determined from samples collected between 1998 and 2003 in the northwestern shelf of the Iberian Peninsula with the purpose of studying the variability in the trophic position of sardine. Sardines were grouped in three size-length classes (small: 20 cm). Plankton samples were size-fractionated between ca. 0.7 and 2000 μm of individual length. The plankton at the base of the pelagic food web in the western shelf region (Galicia) was more enriched in δ15N than plankton in the northern and eastern region (Mar Cantábrico), likely because of upwelling. Variability in δ15N in sardine was related both to changes in feeding strategies during growth and to the mobility of size classes between adjacent shelf regions. Large sardines showed regional differences in δ15N similar to those of small plankton, suggesting that old specimens remained for long periods in the same region. In contrast, small and medium-sized sardines have similar δ15N values in all regions. We hypothesize that interannual differences in δ15N of sardine are caused mainly by variations in the mobility of large size classes, as the isotopic signature of the small sardines was relatively less variable and suggests low variability in the plankton food web. In turn, such variations would be related to changes in the size of the sardine population in the north Iberian shelf

Fisheries interactions of Delphinus delphis in the north-east Atlantic with an emphasis on Galicia, north-west Spain.

Bycatch from interactions with fisherie s remains the biggest global threat to marine mammals. Galicia, north - west Spain, is one of the world’s main fishing regions and a high level of cetacean - fisheries interactions has been reported from on - board observers, interviews with fisheries stakeholde rs and analysis of stranded and by - caught carcasses. Delphinus delphis is the most abundant cetacean in the area and since 1990 necropsies of over 1800 stranded and by - caught Delphinus have been conducted. Life history data (age, maturity, and pregnancy ra te data) from stranded and by - caught cetaceans can be used to construct life tables and to estimate overall mortality and fisheries mortality rates. Age and maturity were determined from stranded and by - caught Delphinus between 1990 and 2009. Males and fem ales reach sexual maturity at 8.5 and 7.5 years of age, respectively, and no temporal difference in age at sexual maturity was observed. Results indicate 13% annual mortality in the Delphinus delphis north - east Atlantic population and necropsy data suggest s that 60% of mortality (i.e. 7.2% annual mortality) is attributable to fisheries interactions, predominantly from pair trawls and gillnets. By - caught Delphinus were found to die significantly younger than non - by - caught animals (p=<0.001) although no sex - r elated difference in bycatch rate was observed (p=0.051). The estimated annual mortality due to fisheries interactions greatly exceeds the 2% limit set by ASCOBANS and the IWC and high bycatch rates are also reported for other countries e.g. the UK, France and Portugal. Although Delphinus delphis in the north - east Atlantic is one continuous population, the high level of bycatch occurring in parts of the range is most likely unsustainable and will be discussed. There is a need to carry out on - board monitorin g, notably in the north - west Iberian Peninsula (Galicia and Portugal), to incorporate cetacean bycatch into fisheries advice and, above all, to start introducing mitigation measures

Are there climatic signals in fishery data for sardine (Sardina pilchardus) along the Iberian Atlantic coast?

The Iberian sardine (Sardina pilchardus) is distributed along the whole shelf of the Iberian Peninsula with the highest catches being taken from southern Galician waters and northern Portugal. The fishery is dependent on the strength of the recruitment in this area and recruitment processes seem to be driven by a combination of oceanographic (local) and climatic (global) events. In an exploratory analysis we examined whether the variability observed in landings from ICES areas VIIIc (northern) and IXa (western Iberia) from 1940 to 2005, and in estimated annual recruitment and spawning stock size for the whole stock could be related to environmental conditions at large and local scales, taking into account temporal autocorrelation in the response variables. Landings for areas VIIIc and IXa show differing trends and were most strongly related, respectively, to the multi-decadal Atlantic oscillation (AMO) and to SST (with an optimum around 15o C). Recruitment was negatively related to air temperature (AT). We stress the need for taking into account time lagged effects, non linear relationships, autocorrelation in response variables and collinearity between explanatory variables. We discuss possible mechanisms underlying these observed patterns and whether the apparent climatic relationships have any predictive value

Sensitivity of conservative pollutants estimation using ISCST3 to input parameters for a case of study

[ES] El presente documento describe un proceso de análisis realizado sobre el modelo gaussiano de dispersión de contaminantes atmosféricos ISCST3 aplicado en un área densamente poblada, el Instituto Superior Politécnico José Antonio Echeverría (CUJAE) ubicado en la Habana. Para la simulación numérica se realizó un inventario de fuentes y de emisiones de contaminantes atmosféricos en la zona, para estimar la concentración del contaminante conservativo, en este caso dióxido de azufre. El objetivo es mostrar la sensibilidad de esta simulación numérica con la variación en la entrada de varios parámetros: albedo medio, razón de Bowen, rugosidad de la superficie y velocidad del viento. Una vez obtenidos los resultados se analiza la influencia de las variaciones en la entrada de dichos parámetros sobre la concentración del contaminante estudiado. Concluyendo que la velocidad del viento es el parámetro al que el modelo es más sensible y presenta la menor sensibilidad a los cambios en la entrada del albedo. El receptor menos afectado en los valores de concentración estimados para 24 horas es el receptor 2, ubicado en el centro de la malla y correspondiente al campus universitario de la CUJAE. Mientras que para valores horarios los menos sensibles son los receptores 1 y 3.[EN] This paper describes a process of analysis of the Gaussian model ISCST3 of air pollutants dispersión applied in a densely populated area, the Higher Polytechnic Institute José Antonio Echeverría (CUJAE) in Havana. For the numerical simulation was carried out a sources and emissions inventory of air pollutants in the área, to estímate the concentration of the conservative pollutant, in this case sulfur dioxide. The objective is to show the sensitivity of numerical simulation with variation in the input of several parameters: average albedo, Bowen ratio, surface roughness and wind speed. After obtaining the results, the influence of variatíons in these parameters input and contaminant concentration studied is analyzed. Concluding that the wind speed is the parameter to which the model is more sensitive and has the lowest sensitivity to changes in albedo input. The least affected receptor concentration values estimated for 24 hours is the number 2, located in the center of the screen and land in the campus CUJAE. While for hourly values, receptors 1 and 3 are less sensitive.Los autores agradecen al proyecto de Doctorado auricular en su dimensión ambiental existente entre el Instituto Superior Politécnico José Antonio Echeverría (CUJAE) y la Universidad Politécnica de Valencia que permitió en el marco del mismo la realización de este trabajo. Además de nuestra gratitud a otras instituciones que facilitaron los datos y medios para la investigación como son: Dirección Provincial de Salud Pública de ciudad de La Habana, Cuba energía perteneciente al Ministerio de Ciencia Tecnología y Medio Ambiente y a la Oficina de Acción Internacional (OIA) de la Universidad Politécnica de Valencia.González-Cruz, M.; Pire-Rivas, S.; López Jiménez, PA. (2012). Sensibilidad del modelo ISCST3 en la estimación de contaminantes conservativos: Caso de estudio. REVISTA MEXICANA DE INGENIERÍA QUÍMICA. 11(2):287-298. http://hdl.handle.net/10251/150423S28729811

Antioxidant and hypoglycemic effects of watercress (Nasturtium officinale) extracts in diabetic rats

Background: Watercress is a semi-aquatic plant used in traditional medicine to treat various ailments, such as flu, cough, avitaminosis, and anorexia; it is also used as a diuretic and for hypoglycemia treatment in diabetes. In this study, we report the antioxidant and hypoglycemic activity of orally administered aqueous (WAQE), acetonic (WAE), and alcoholic (WOHE) watercress extracts. The effect of subchronic administration of watercress extracts on oxidative stress was also studied.Materials and Methods: WAQE, WAE, and WOHE were obtained and administered orally. Alloxan (200 mg/kg) and streptozotocin (60 mg/kg) were applied to induce hyperglycemia in male Wistar rats. Phenolic and flavonoid content, as well as antioxidant activity of the extracts were measured. The acute and subchronic effects (8 weeks) of WAQE were evaluated. The activity of antioxidant enzymes levels of malondialdehyde, hepatic enzyme markers in the serum, and renal function markers, were assessed. Histopathological evaluation of the pancreas, kidney, and liver was performed using hematoxylin-eosin staining.Results: Watercress extracts have high concentrations of phenols, polyphenols, and flavonoids, in addition to a very high antioxidant effect. The hypoglycemic effect of WAQE upon acute administration was 76.6% higher than that of insulin. When administered chronically, glucose levels were normalized on the third week up to the eighth week. Furthermore, the antioxidant enzymes and biochemical parameters improved.Conclusion: WAQE administration to diabetic rats reduced oxidative stress damage and decreased glucose levels. This study supports the use of this plant for the treatment of diabetes.Keywords: Antioxidant, Diabetes, Watercress (Nasturtium officinale), Oxidative stress, Pancrea

Biopreservation of fresh-cut pear using Lactobacillus rhamnosus GG and effect on quality and volatile compounds

In recent years, the consumption of minimally processed fruit has increased. However, unfortunately, these products could be an appropriate vehicle for the transmission of foodborne pathogens. In this study, the antagonistic capacity of the probiotic strain Lactobacillus rhamnosus GG against a cocktail of 5 serovars of Salmonella and 5 serovars of Listeria monocytogenes on fresh-cut pear at conditions simulating commercial application was assessed. Moreover, its effect on fruit quality, particularly on the volatile profile, was determined, during 9 days of storage at 5 C. L. monocytogenes population was reduced by approximately 1.8 log-units when co-inoculated with L. rhamnosus GG. However, no effect was observed in Salmonella. Fruit quality (soluble solids content and titratable acidity) did not change when the probiotic was present. A total of 48 volatile compounds were identified using gas chromatography. Twelve of the compounds allowed to discriminate L. rhamnosus GG-treated and untreated pears. Considering their odour descriptors, their increases could be positive in the flavour perception of L. rhamnosus GG-treated pear. The probiotic was able to control L. monocytogenes population on fresh-cut pear, which could be a vehicle of probiotic microorganisms as quality of fruit was not affected when the probiotic was presentinfo:eu-repo/semantics/acceptedVersio