Papers by Miguel Contreras
Advances in Intelligent Systems and Computing, 2015
Numeros, 2011
Además de la presencia constante de información estadística en los medios de comunicación, muchos... more Además de la presencia constante de información estadística en los medios de comunicación, muchos organismos nacionales e internacionales proporcionan en la actualidad acceso libre a sus bases de datos de información estadística a través de Internet. Surge como consecuencia la demanda social de educación estadística que permita comprender e interpretar esta información en la toma de decisiones. En este trabajo sintetizamos la investigación que describe las competencias requeridas en la construcción y lectura crítica de tablas y gráficos estadísticos.
1Er Simposio Sobre Los Carpetanos Arqueologia E Historia De Un Pueblo De La Edad Del Hierro 2014 Isbn 978 84 451 3497 9 Pags 377 386, 2014
A process for fabricating slightly Cu-poor thin-films of Cu(In,Ga)Se.sub.2 on a substrate for sem... more A process for fabricating slightly Cu-poor thin-films of Cu(In,Ga)Se.sub.2 on a substrate for semiconductor device applications includes the steps of forming initially a slightly Cu-rich, phase separated, mixture of Cu(In,Ga)Se.sub.2 :Cu.sub.x Se on the substrate in solid form followed by exposure of the Cu(In,Ga)Se.sub.2 :Cu.sub.x Se solid mixture to an overpressure of Se vapor and (In,Ga) vapor for deposition on the Cu(In,Ga)Se.sub.2 :Cu.sub.x Se solid mixture while simultaneously increasing the temperature of the solid mixture toward a recrystallization temperature (about 550.degree. C.) at which Cu(In,Ga)Se.sub.2 is solid and Cu.sub.x Se is liquid. The (In,Ga) flux is terminated while the Se overpressure flux and the recrystallization temperature are maintained to recrystallize the Cu.sub.x Se with the (In, Ga) that was deposited during the temperature transition and with the Se vapor to form the thin-film of slightly Cu-poor Cu.sub.x (In,Ga).sub.y Se.sub.z. The initial Cu-rich, phase separated large grain mixture of Cu(In,Ga)Se.sub.2 :Cu.sub.x Se can be made by sequentially depositing or co-depositing the metal precursors, Cu and (In, Ga), on the substrate at room temperature, ramping up the thin-film temperature in the presence of Se overpressure to a moderate anneal temperature (about 450.degree. C.) and holding that temperature and the Se overpressure for an annealing period. A nonselenizing, low temperature anneal at about 100.degree. C. can also be used to homogenize the precursors on the substrates before the selenizing, moderate temperature anneal.
A process for producing a slightly Cu-poor thin film of Cu(In,Ga)(Se,S).sub.2 comprises depositin... more A process for producing a slightly Cu-poor thin film of Cu(In,Ga)(Se,S).sub.2 comprises depositing a first layer of (In,Ga).sub.x (Se,S).sub.y followed by depositing just enough Cu+(Se,S) or Cu.sub.x (Se,S) to produce the desired slightly Cu-poor material. In a variation, most, but not all, (about 90 to 99%) of the (In,Ga).sub.x (Se,S).sub.y is deposited first, followed by deposition of all the Cu+(Se,S)
Applied Physics Letters, 2008
Applied Physics Letters, Sep 27, 1993
An important development in polycrystalline Cu(In,Ga)Se2 (CIGS) thin-film photovoltaic solar cell... more An important development in polycrystalline Cu(In,Ga)Se2 (CIGS) thin-film photovoltaic solar cells is the attainment of a high voltage device simultaneous with state-of-the-art conversion efficiency. This letter describes a CIGS-based solar cell that demonstrates an open-circuit voltage approaching 700 mV and a total-area conversion efficiency of 12.2 percent. The high value of open-circuit voltage was achieved by grading In/Ga through the absorber by a computer-controlled physical vapor deposition process that utilizes variable metal fluxes.
We discuss our current research focus on photovoltaic (PV) informatics, which is dedicated to fun... more We discuss our current research focus on photovoltaic (PV) informatics, which is dedicated to functionality enhancement of solar materials through data management and data mining-aided, integrated computational materials engineering (ICME) for rapid screening and identification of multi-scale processing/structure/property/performance relationships. Our current PV informatics research ranges from transparent conducting oxides (TCO) to solar absorber materials. As a test bed, we report
1Er Simposio Sobre Los Carpetanos Arqueologia E Historia De Un Pueblo De La Edad Del Hierro 2014 Isbn 978 84 451 3497 9 Pags 279 292, 2014
Brain Research, 2001
Our laboratory has developed an in vivo method to quantitatively evaluate phospholipase A(2) (PLA... more Our laboratory has developed an in vivo method to quantitatively evaluate phospholipase A(2) (PLA(2))-mediated signal transduction in brain regions of rodents. In this method, quantitative autoradiography is used to identify brain uptake of intravenously injected, radiolabeled arachidonic acid ([3H]AA). Dopamine D(2) receptors are coupled to G-proteins that activate PLA(2), releasing AA from the stereospecifically numbered (sn) 2 position of phospholipids, and regional [3H]AA uptake is proportional to the rate of release. In the present experiment, the D(2) antagonist haloperidol (1.0 mg/kg i.p.) or the drug vehicle was administered to male adult rats for 21 days. Rats were infused 3 days later with 1.75 mCi/kg [3H]AA (i.v.), anesthetized and decapitated 20 min after infusion onset, and brains were processed for quantitative autoradiography. Chronic haloperidol significantly decreased [3H]AA incorporation in two primary dopaminergic basal ganglia-frontal cortex circuits, the mesocorticolimbic and nigrostriatal systems, while insignificant changes in AA incorporation were noted in other brain regions. These results suggest that one mechanism by which haloperidol exerts its effect is by downregulating D(2)-mediated PLA(2) signaling involving AA release in basal ganglia-frontal cortex circuitry.
2014 Ieee 40th Photovoltaic Specialist Conference, Jun 1, 2014
The Faseb Journal, Apr 1, 2007
Revista Digital: Matemática, Educación e Internet, 2014
En este trabajo analizamos algunos de los sesgos frecuentes en la comprensión de la probabilidad ... more En este trabajo analizamos algunos de los sesgos frecuentes en la comprensión de la probabilidad condicional. También presentamos algunos resultados obtenidos en dos estudios de evaluación realizados con estudiantes de Psicología y futuros profesores de matemáticas en España. Finalizamos con algunas reflexiones sobre la enseñanza de la probabilidad.
A process for producing a slightly Cu-poor thin film of Cu(In,Ga)(Se,S).sub.2 comprises depositin... more A process for producing a slightly Cu-poor thin film of Cu(In,Ga)(Se,S).sub.2 comprises depositing a first layer of (In,Ga).sub.x (Se,S).sub.y followed by depositing just enough Cu+(Se,S) or Cu.sub.x (Se,S) to produce the desired slightly Cu-poor material. In a variation, most, but not all, (about 90 to 99%) of the (In,Ga).sub.x (Se,S).sub.y is deposited first, followed by deposition of all the Cu+(Se,S)
DOE Scientific and Technical Information. DOE Scientific and Technical Information. ...
Current Opinion in Lipidology, Jul 1, 2002
Recent literature provides a basis for understanding the behavioral, functional, and structural c... more Recent literature provides a basis for understanding the behavioral, functional, and structural consequences of nutritional deprivation or disease-related abnormalities of n-3 polyunsaturated fatty acids. The literature suggests that these effects are mediated through competition between n-3 and n-6 polyunsaturated fatty acids at certain enzymatic steps, particularly those involving polyunsaturated fatty acid elongation and desaturation. One critical enzymatic site is a delta6-desaturase. On the other hand, an in-vivo method in rats, applied following chronic n-3 nutritional deprivation or chronic administration of lithium, indicates that the cycles of de-esterification/re-esterification of docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6) within brain phospholipids operate independently of each other, and thus that the enzymes regulating each of these cycles are not likely sites of n-3/n-6 competition.
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Papers by Miguel Contreras