2,261 research outputs found
Cooling Curve Analysis Method using a Simplified Energy Balance
In this work is described a new cooling curve analysis method focused on the experimental determination of the latent heat of phase changes and phase transformation kinetics.The method analyses the cooling process of a metallic sample, initially liquid that is contained into a cylindrical metallic mold, both of known weight, thermally isolated at its top and bottom. The method is based on a simplified energy balance associated with the experimental measurement of the temperature change of the sample during its cooling process. The method was applied experimentally to zinc and tin of commercial purity, initially liquids and contained into stainless steel molds in order to determine its ability to determine the latent heat of solidification. In order to validate the method, the obtained values of latent heat were compared with the values reported in thermochemical databases. The obtained results suggest that this method can be used to characterize the solidification of metals..Keywords: Solidification, Kinetics; Cooling curve analysis
GP_BOT: plataforma hardware para la enseñanza de robótica en la titulación de ingeniería informática.
Versión electrónica de la ponencia presentada en V Congreso de Tecnologías Aplicadas a la Enseñanza de la Electrónica, celebrado en Las Palmas de Gran Canaria en 2002En este artículo se resumen las principales características de unas tarjetas basadas en el
microcontrolador MC68HC908GP32 de Motorola, que se utilizan en el Laboratorio de la
asignatura Robótica Autónoma en la carrera de Ingeniería Informática de la Universidad
Autónoma de Madrid
Control de acceso mediante tarjeta chip: Aplicaciones de Control a través de Internet
Versión electrónica de la ponencia presentada en V Congreso de Tecnologías Aplicadas a la Enseñanza de la Electrónica, celebrado en Gran Canaria en 2002En este artículo se presenta un sistema real de control de accesos desarrollado por alumnos
de nuestra Escuela. Este proyecto ha servido de plataforma para desarrollar los
conocimientos no sólo de sistemas embebidos basados en microcontrolador, sino también
para practicar las comunicaciones TCP/IP y el desarrollo de la base de datos de usuarios y
su software de gestión
The molecular phylogenetics of the genus Oligoryzomys (Rodentia: Cricetidae) clarifies rodent host-Hantavirus associations
Several species of the genus Oligoryzomys are natural hosts of different hantavirus genotypes affecting humans. The systematics of the genus is confusing, which complicates the identification of the rodent host and hence the potential endemic areas of hantavirus pulmonary syndrome. In this study, we analyse molecular data to infer phylogenetic relationships among Central and South American specimens of Oligoryzomys, and compare our results with previously published data on karyotypic, geographic distribution and host–virus associations to solve contradictory taxonomic reports. We identified 25 clades, each one corresponding to a different putative species. The phylogenetic trees show that Oligoryzomys longicaudatus is strongly related to the Oligoryzomys flavescens complex, which comprises four clades; Oligoryzomys nigripes is related to Oligoryzomys stramineus, Oligoryzomys vegetus is related to Oligoryzomys fulvescens from Central America, and Oligoryzomys brendae is the sister species of Oligoryzomys aff. destructor. We identified the following rodent host–hantavirus genotype relationships: O. longicaudatus–Andes; O. flavescens ‘West'–Bermejo; O. flavescens ‘East'–Lechiguanas; O. nigripes–Juquitiba; Oligoryzomys microtis–Rio Mamore and Rio Mamore-3; Oligoryzomys chacoensis–Oran; Oligoryzomys costaricencis–Choclo; Oligoryzomys delicatus–Maporal; Oligoryzomys utiaritensis–Castelo dos Sonhos; Oligoryzomys sp. RT2012–Rio Mamore-4; Oligoryzomys sp. (and not Oligoryzomys fornesi)–Anajatuba. This work, besides contributing to the development of prevention programmes for hantavirus epidemiology in Latin America, represents a comprehensive update of the systematics of the genus Oligoryzomys.Fil: González Ittig, Raúl Enrique. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; ArgentinaFil: Rivera, Paula Cecilia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; ArgentinaFil: Levis, Silvana C.. Direccion Nacional de Instituto de Investigacion. Adm.nacional de Laboratorio E Instituto de Salud "dr.c.g.malbran". Instituto Nacional de Enfermedades Virales Humanas; ArgentinaFil: Calderón, Gladys E.. Direccion Nacional de Instituto de Investigacion. Adm.nacional de Laboratorio E Instituto de Salud "dr.c.g.malbran". Instituto Nacional de Enfermedades Virales Humanas; ArgentinaFil: Gardenal, Cristina Noemi. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; Argentin
Artificial intelligence assisted Mid-infrared laser spectroscopy in situ detection of petroleum in soils
A simple, remote-sensed method of detection of traces of petroleum in soil combining
artificial intelligence (AI) with mid-infrared (MIR) laser spectroscopy is presented. A portable MIR
quantum cascade laser (QCL) was used as an excitation source, making the technique amenable to
field applications. The MIR spectral region is more informative and useful than the near IR region for
the detection of pollutants in soil. Remote sensing, coupled with a support vector machine (SVM)
algorithm, was used to accurately identify the presence/absence of traces of petroleum in soil mixtures.
Chemometrics tools such as principal component analysis (PCA), partial least square-discriminant
analysis (PLS-DA), and SVM demonstrated the e ectiveness of rapidly di erentiating between
di erent soil types and detecting the presence of petroleum traces in di erent soil matrices such as
sea sand, red soil, and brown soil. Comparisons between results of PLS-DA and SVM were based
on sensitivity, selectivity, and areas under receiver-operator curves (ROC). An innovative statistical
analysis method of calculating limits of detection (LOD) and limits of decision (LD) from fits of the
probability of detection was developed. Results for QCL/PLS-DA models achieved LOD and LD
of 0.2% and 0.01% for petroleum/soil, respectively. The superior performance of QCL/SVM models
improved these values to 0.04% and 0.003%, respectively, providing better identification probability
of soils contaminated with petroleum
Implementation of an Artificial Neural Network on the Test Barcelona Workstation As a Predictive Model for the Classification of Normal, Mild Cognitive Impairment and Alzheimer’s Disease Subjects Using the Neuronorma Battery
Objective: To develop and implement an online Artificial Neural Network (ANN) that provides the probability of a subject having mild cognitive impairment (MCI) or Alzheimer’s disease (AD).
Method: Different ANNs were trained using a sample of 350 controls (CONT), 75 MCI and 93 AD subjects. The ANN structure chosen was the following: (1) an input layer of 33 cognitive variables from the Neuronorma battery plus two sociodemographic variables, age and education. This layer was reduced to a 15 features input vector using Multiple Discriminant Analysis method, (2) one hidden layer with 8 neurons, and (3) three output neurons corresponding to the 3 expected cognitive states. This ANN was defined in a previous study [28]. The ANN was implemented on the web site www.test-barcelona.com (Test Barcelona Workstation) [9].
Results: When comparing CONT, MCI and AD participants, the best ANN correctly classifies up to 94,87% of the study participants.
Conclusions: The online implemented ANN, delivers the probabilities (%) of belonging to the CONT, MCI and AD groups of a subject assessed using the 35 characteristics (variables) of the Neuronorma profile. This tool is a good complement for the interpretation of cognitive profiles. This technology improves clinical decision making.
Keywords: Artificial Neural Network, Probability, Alzheimer disease, Test Barcelona Workstation
Selective Estrogen Receptor Modulators Regulate Dendritic Spine Plasticity in the Hippocampus of Male Rats
Some selective estrogen receptor modulators, such as raloxifene and tamoxifen, are neuroprotective and reduce brain inflammation in several experimental models of neurodegeneration. In addition, raloxifene and tamoxifen counteract cognitive deficits caused by gonadal hormone deprivation in male rats. In this study, we have explored whether raloxifene and tamoxifen may regulate the number and geometry of dendritic spines in CA1 pyramidal neurons of the rat hippocampus. Young adult male rats were injected with raloxifene (1 mg/kg), tamoxifen (1 mg/kg), or vehicle and killed 24 h after the injection. Animals treated with raloxifene or tamoxifen showed an increased numerical density of dendritic spines in CA1 pyramidal neurons compared to animals treated with vehicle. Raloxifene and tamoxifen had also specific effects in the morphology of spines. These findings suggest that raloxifene and tamoxifen may influence the processing of information by hippocampal pyramidal neurons by affecting the number and shape of dendritic spines
DETERMINACIÓN DE LA PRESENCIA DE TUBERCULOSIS BOVINA EN LA PROVINCIA DE CANTA, LIMA
La presencia de tuberculosis bovina fue determinada en 503 bovinos mayores de 4 semanas de edad en la provincia de Canta, departamento de Lima, con la prueba de tuberculina (PPD). La lectura de la prueba fue realizada 72 horas después de la inyección intradérmica. Once de 503 bovinos (2.2%) fueron reactores positivos a la prueba de tuberculina. Estos resultados fueron analizados por la técnica de evaluación de riesgos por simulación Monte Carlo (programa @Risk) indicando que la probabilidad de encontrar un animal infectado en los bovinos de la provincia de Canta; Lima, es mayor al 1% y menor al 3.2%.The presence of bovine tuberculosis was determined in 503 cattle older than four weeks from Canta province, Lima by the tuberculin skin test (PPD). Lecture of the test was performed 72 hours after intradermal injection. Eleven out of 503 animals (2.2%) were positive to cutaneous tuberculin stimuli. These results were analyzed by the risk evaluation technique using Monte Carlo simulation (@ Risk Program) and the probability of finding the infection in cattle from Canta province resulted greater than 1% and less than 3.2%
Analysis of the Relationship between Lifestyle and Coffee Consumption Habits, from the Myth Approach, in the Municipalities of Orizaba, Tehuipango, and Zongolica Veracruz.
Coffee consumption habits have evolved along with society for more than 300 years around the world. Social changes imply different lifestyles in each culture. Lifestyles influence the myths used by people in their consumption decisions. The objective of this research is to determine the relationship between lifestyle and coffee consumption habits, from the perspective of myth, in the inhabitants of the Mexican municipalities of Orizaba, Tehuipango, and Zongolica. A survey was conducted with a sample of inhabitants of the three municipalities studied. The statistical analyzes applied were the central limit theorem, Pearson, and Chi-square. The results show that the variables Consumption habits-Lifestyle-Myth, are highly dependent on the level of perception of people. It is concluded that the coffee myth corresponds to the "family union" in the study municipalities. This myth is not characterized in the evolutionary stages contemplated in the "waves of coffee"
Social Emotional Health Survey-Secondary (SEHS-S): A Universal Screening Measure of Social-Emotional Strengths for Spanish-Speaking Adolescents
The Social Emotional Health Survey-Secondary (SEHS-S), which is a measure of core psychological assets based on a higher-order model of Covitality, is comprised of 36 items and four latent traits (with three measured subscales): belief in self (self-efficacy, self-awareness, and persistence), belief in others (school support, family coherence, and peer support), emotional competence (emotional regulation, behavioral self-control, and empathy), and engaged living (gratitude, zest, and optimism). Previous international studies have supported the psychometric properties of the SEHS-S. The present study extended this research by examining the psychometric properties of a Spanish-language adaptation with a sample of 1042 Spanish adolescents (Mage = 14.49, SD = 1.65.). Confirmatory factor analyses replicated the original factorial structure, with hierarchical omega between 0.66–0.93, with 0.94 for the total score. Factorial invariance across genders revealed small latent mean differences. A path model evaluated concurrent validity, which revealed a significant association between Covitality and bidimensional mental health (psychological distress and well-being). Specifically, correlational analyses showed a negative association with internalizing/externalizing symptoms, and positive associations with subjective well-being, health-related quality of life, and prosocial behaviors. This study provides an example of a culturally relevant adaptation of an international tool to measure student strengths, which is critical to planning school programming and policy.The Ministry of Economy, Industry, and Competitiveness of the Government of Spain (I+D+i Projects, 2017, reference number: PSI2017-88280-R, and Research Networks PSI2015-70943-REDT and PSI2017-90650-REDT) and the Department of Education, Research, Culture, and Sport from Valencian Community of Spain through two grants for the hiring of PhD research assistant awarded to M.R-R. [ACIF/2015/155; VALi+d Program) and R.F. (ACIF/2019/052; VALi+d Program) funded this research
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