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Search Results: 1 - 10 of 236714 matches for " William; Vergara R "
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Penfigoide gestacional "Herpes gestationis": Revisión a partir de un caso clínico
de la Cruz F,Claudia; Navarrete D,Cristián; Majerson G,Daniela; Romero G,William; Vergara R,Angie; González B,Sergio;
Revista chilena de obstetricia y ginecología , 2012, DOI: 10.4067/S0717-75262012000100013
Abstract: the pregnant woman is susceptible to both physiologic and pathologic changes of the skin and appendages. recognition of these entities is important for appropriate management. the classification and nomenclature have been controversial and confusing, mainly because of the poor knowledge that we have regarding the origin of this entities. the purpose of this review is to contribute to the current knowledge of pemphigoid gestationis, based on a case-report its diagnosis and treatment as a multidisciplinary pathology.
Bioavailability of Chlorpyrifos in Wheat Plants (Triticum aestivun)  [PDF]
Sylvia V. Copaja, Rosa Vergara, Héctor R. Bravo
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.58069
Abstract:

Adsorption processes of chlorpyrifos in two Chilean agro soils (Calera: C; San Esteban: SE) in relation with the bioaccumulation in wheat plants (Triticum aestivun) were studied. RP-HPLC method was developed to determine the chlorpyrifos content in soils, roots and seedling tissues. The two soils showed high adsorption capacity (C = 78%, SE = 92%). The values are not in relation with the contents of organic matter (C = 3.9% and SE = 2.0%) and clay (C = 12.7% and SE = 10.1%) determined in the soils. Persistence and mobility of chlorpyrifos in the soils were estimated from halflife values (Csoil = 23 d, SEsoil = 14 d) and the Guss index (Csoil = 0.89, SEsoil = 0.25) respectively. These values are in the range of non-leaching compounds, and suggest that there should be no pollutant in the ground water. Wheat plants grown in both soils incubated with chlorpyrifos bioaccumulate residues in roots and seedling tissues. Root tissues showed the greatest contents (C = 22.3 mg/k. f. wt; SE = 51.8 mg/kg. f. wt.). Germination and growth of wheat young plants were not inhibited for the contents in the tissues. A relation between the levels of chlorpyrifos residues in the soils and the bioaccumulation in wheat tissues was estimated from the BAI parameter. Values showed that the bioaccumulation is dependent on the residues contents in soils. These results suggest that bioavailability of chlorpyrifos in wheat plants may be a harmful pollutant for mammals if it remains stable at all growth stage of the plant. Further research should be considered to see if bioavailability in forage and/or grain can occur.

Occupational Wages and Globalization  [PDF]
William R. DiPietro
iBusiness (IB) , 2011, DOI: 10.4236/ib.2011.32023
Abstract: Using a country’s trade share as a measure of globalization, this paper employs cross country regression analysis on 161 occupations for the year 2000 to assess whether globalization has a negative effect on occupational wages. The results are consistent with the notion that greater integration of national economies with the rest of the world adversely affects occupational wages in many occupations within countries.
Análise da atividade: a extra??o de conhecimentos
Vergara, Walter R. Hernández;
Psicologia: Reflex?o e Crítica , 1997, DOI: 10.1590/S0102-79721997000100012
Abstract: the extraction of knowledge is sometimes seen as a technical reference to the conception of the specialist systems and of systems based on knowledge. the present paper intends to present some reflections designed to provide greater psychological insights to this problem. in this work, i try to show how the problem knowledge extration is understood by ergonomic and by artificial intelligence, how knowledge can be obtained throught different objectives, and finally, i analyze the domain of construction of a help system for decision making. the latter objective is emphasized because of its relation to cognitive ergonomics which in turn stresses multiple levels of activity regulation. these levels and kinds of knowledge with which the operator deals must be understood before we can approach the methodological questions converning the acess to knowledges itself.
Análise da atividade: a extra o de conhecimentos
Vergara Walter R. Hernández
Psicologia: Reflex?o e Crítica , 1997,
Abstract: Considerando-se o atual estágio de desenvolvimento de sistemas especialistas e de sistemas baseados no conhecimento, em que a extra o de conhecimentos é, às vezes, vista como uma referência técnica à concep o desses sistemas, proporciona-se neste trabalho um conjunto de reflex es que d o uma melhor claridade psicológica ao assunto. No artigo, mostra-se como é visto o problema de extra o de conhecimentos pela Ergonomia e Inteligência Artificial; como a extra o pode ser obtida por diferentes objetivos e, finalmente, analisa-se o domínio da constru o de um sistema de ajuda para decis o. Privilegiamos este último objetivo, próprio da Ergonomia Cognitiva, porque somos conduzidos a tomar o quadro teórico da Psicologia, que enfatiza uma multiplicidade de níveis de regula o da atividade e de formas de conhecimentos tratados pelo operador, antes de abordar as quest es metodológicas de acesso a esses conhecimentos.
Unemployment Benefits and Unemployment  [PDF]
William Beranek, David R. Kamerschen
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.25088
Abstract: This paper seeks to provide a simpler explanation of the Match Quality Hypothesis (MQH). For the less mathematically inclined, it avoids formal analysis and yet derives the relevant implications, i.e., if unemployed workers currently collecting unemployment benefits are given more benefits, both the average period of unemployment duration increases as well as the level of unemployment. To produce these effects, only one person behaving in this manner is required. We cite recent evidence supporting these implications. Examined are implications of this theorem for both U.S. and European regions where, in some cases, voluntarily unemployed workers are eligible for unemployment benefits. We question the importance of the notion that generous unemployment benefits that intensify searches for better jobs, and hence prolonged job searches, ultimately yield societal benefits.
Evolución de la infección con Trypanosoma cruzi en cepas susceptibles y resistentes de ratones
ZU?IGA,C; VARGAS,R; VERGARA,U;
Archivos de medicina veterinaria , 2002, DOI: 10.4067/S0301-732X2002000200004
Abstract: mice from aca and a.sn strains were equally susceptible (100% mortality) to intraperitoneal infection with 2000 blood trypomastigotes from tulahuen strain of trypanosoma cruzi, while a.sw and hti strains were resistant (100% survival). however mice from a.sw and hti strains showed significantly higher level of parasitemia than the susceptible strains. the histopathology of miocardial and skeletal muscle was evaluated in the susceptible and resistant strains of mice. in the first ten days post-infection no significant differences in tissue damage were observed. however in the third week of infection, while a.sw and hti mice showed recovery of tissue lessions, the susceptible a.sn and aca showed increased tissue damage although no blood forms and intracellular parasites were detected. serum samples from infected mice were tested by dot-immunoradiometric assay, for reactivity against recombinant antigens 1,2,13,26,30,36 and sapa of t. cruzi. all mice sera only reacted with clones 13 and sapa, suggesting that this reactivity seems not to be involved in susceptibility or resistance to infection with tulahuen strain of t. cruzi
Evolución de la infección con Trypanosoma cruzi en cepas susceptibles y resistentes de ratones Evolution of Trypanosoma cruzi infection in resistant and susceptible mice
C ZU?IGA,R VARGAS,U VERGARA
Archivos de medicina veterinaria , 2002,
Abstract: Ratones de las cepas ACA y A.Sn fueron altamente susceptibles, con un 100% de mortalidad alrededor de las 3 semanas postinfección (p.i), con un inóculo por vía intraperitoneal de 2000 tripomastigotes sanguíneos de la cepa Tulahuen de Trypanosoma cruzi, mientras que las cepas A.Sw y HTI se comportaron como resistentes con un 100% de sobrevida, pasados los 6 meses p.i. Sin embargo, los animales de las cepas resistentes mostraron niveles máximos de parasitemia significativamente más altos que las cepas susceptibles. Se realizó un estudio histopatológico de músculo cardíaco y esquelético de los ratones infectados. En los primeros 10 días p.i. no se observaron diferencias claras entre cepas resistentes y susceptibles, en cuanto al da o tisular y presencia de parásitos intracelulares (pseudoquistes). Pero alrededor de la tercera semana p.i. ya se vieron diferencias evidentes, mientras los animales de las cepas A.Sw y HTI mostraron bajos niveles de inflamación y signos de recuperación de las lesiones, los ratones ACA y A.Sn evidenciaron un progresivo aumento del da o tisular, aunque no se observaron, en este momento, formas sanguíneas ni intracelulares del parásito. Muestras de suero de los ratones infectados fueron probados por un ensayo inmunoradiométrico (IRMA), para analizar la reactividad contra los antígenos recombinantes 1,2,13,26,30,36 y SAPA de T. cruzi. Todos los sueros sólo mostraron reconocimiento de las proteínas 13 y SAPA, sugiriendo que esta reactividad no pareciera estar relacionada directamente con el fenómeno de resistencia o susceptibilidad a la infección con la cepa Tulahuen de T. cruzi, en el modelo murino Mice from ACA and A.Sn strains were equally susceptible (100% mortality) to intraperitoneal infection with 2000 blood trypomastigotes from Tulahuen strain of Trypanosoma cruzi, while A.Sw and HTI strains were resistant (100% survival). However mice from A.Sw and HTI strains showed significantly higher level of parasitemia than the susceptible strains. The histopathology of miocardial and skeletal muscle was evaluated in the susceptible and resistant strains of mice. In the first ten days post-infection no significant differences in tissue damage were observed. However in the third week of infection, while A.Sw and HTI mice showed recovery of tissue lessions, the susceptible A.Sn and ACA showed increased tissue damage although no blood forms and intracellular parasites were detected. Serum samples from infected mice were tested by dot-immunoradiometric assay, for reactivity against recombinant antigens 1,2,13,26,30,36 and SAPA of T. cruzi
A Review of Feature Selection Methods Based on Mutual Information
Jorge R. Vergara,Pablo A. Estévez
Computer Science , 2015, DOI: 10.1007/s00521-013-1368-0
Abstract: In this work we present a review of the state of the art of information theoretic feature selection methods. The concepts of feature relevance, redundance and complementarity (synergy) are clearly defined, as well as Markov blanket. The problem of optimal feature selection is defined. A unifying theoretical framework is described, which can retrofit successful heuristic criteria, indicating the approximations made by each method. A number of open problems in the field are presented.
Proteína Tax (HTLV-I), probable factor patogénico y marcador del síndrome sicca que se asocia a HAM/TSP
Cartier R,Luis; Vergara R,Carmen; Ramírez V,Eugenio;
Revista médica de Chile , 2005, DOI: 10.4067/S0034-98872005001000007
Abstract: human t-cell lymphotropic virus type i (htlv-i) is a retrovirus that influences cellular metabolism modifying biological responses. this results in oncogenic, degenerative or inflammatory changes. the myelopathy associated to htlv-i or tropical spastic paraparesia (ham/tsp) is a mainly degenerative response to the virus infection. on the other hand, sj?gren syndrome has an inflammatory appearance. the immunohistochemical study of cd-4, cd-8 and cd45 lymphocytes, metalloproteinase mmp-9 and viral tax protein in pathological samples of salivary glands may help to differentiate primary from viral sicca syndrome. aim: to perform an immunohistochemical study of salivary glands of patients with ham/tsp and sicca syndrome and control subjects. material and methods: pathological samples of salivary glands from 53 patients with ham/tsp and sicca syndrome and 10 control subjects, were studied. immunohistochemistry was performed using antibodies against cd-4, cd-8 and cd-45 lymphocytes, metalloproteinase mmp-9 and viral tax protein. results: only in patients with ham/tsp and sicca syndrome, the presence of tax protein was observed in cd-4 and cd-8 lymphocytes and in glandular acini. conclusions: patients infected with htlv-i express tax protein in salivary glands. this finding has diagnostic and pathogenic implications (rev méd chile 2005; 133: 1183-90)
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