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Search Results: 1 - 10 of 23338 matches for " Sandra Luz; Chávez ávila "
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Morfogénesis in vitro de dioon merolae de Luca, Sabato & Vázquez-Torres (zamiaceae, cycadales) a partir de megagametofitos y embriones cigóticos
Cabrera Hilerio,Sandra Luz; Chávez ávila,Victor Manuel; Sandoval Zapotitla,Estela; Litz,Richard E; Cruz Sosa,Francisco;
Interciencia , 2008,
Abstract: organogenic cultures were induced from zygotic embryo and megagametophyte explants of the chiapas state (méxico) endangered cycad species, dioon merolae. the litz induction medium consisted of b5 major salts, ms medium minor salts and the organics glutamine (400mg·l-1), arginine (100mg·l-1), asparagines (100mg·l-1), sucrose (60g·l-1), gellan gum (4g), and supplemented with 0, 0.45, 2.26, 4.52 and 9.05μm 2,4-dichlorophenoxyacetic acid (2,4-d) and 0, 2.32, 4.60, 9.30, 13.90μm kinetin (k), arranged as a 5′5 factorial in a randomized block design. cultures were maintained in darkness at 25°c, and callus was subcultured onto fresh medium at 4 week intervals. callus initiation occurred on a wide range of plant growth regulators (pgr) combinations from megagametophyte explants. in comparison, callus initiation from explanted zygotic embryos occurred on few pgr combinations. adventitious shoot induction occurred from callus on formulations with k and 2,4-d. through the histological analysis of longitudinal sections of zygotic embryos were detected apical meristematic cells of the shoot and root and in megagametophytes the formation of elements similar to tracheids and coralloid roots. this technique has a great potential for preservation of the highly endangered cycads.
Physico-Chemical and Microbiological Analysis of Water of the “Presa De Los Patos” in the Desierto De Los Leones National Park, Mexico  [PDF]
Luis Raúl Gutiérrez-Lucas, Luz María Chávez-Ramírez, Leticia Arregui
Advances in Biological Chemistry (ABC) , 2017, DOI: 10.4236/abc.2017.72008
Abstract: The Desierto de los Leones National Park is a place that features recreational activities for residents and visitors to Mexico City. The Presa de los Patos (Ducks Dam) is one of the many bodies of water that are present in the park. By means of physico-chemical and microbiological analysis, it was determined that the water of the Presa de los Patos cannot be considered potable. The pH range was between 5.5 - 5.9. The turbidity exceeded the values established in the standards (10.7 - 32.3 Nephelometric Turbidity Units (NTU’s)). Chemical Oxygen Demand (COD) showed that large amounts of oxygen are needed to oxidize organic matter (106 - 450 mg/L). The amount of coliforms and fecal coliforms exceeds the values established by the standards used (total coliforms 98 - 956 Colony Forming Units (CFU’s), fecal coliforms 78 - 807 CFU’s). Five bacterial genera (Escherichia coli, Pseudomona, Klebsiella, Shigella and Salmonella) were isolated and identified. Most of the bacteria isolated were resistant to ampicillin (90%), while 25% were resistant to ciprofloxacin. The water consumption of the Presa de los Patos is a great risk for the habitants and visitors of the park.
La escuela básica en la prevención del consumo de alcohol y tabaco: retrato de una realidad
Chávez, Luz María Carvajal;Andrade, Denise de;
Revista Latino-Americana de Enfermagem , 2005, DOI: 10.1590/S0104-11692005000700004
Abstract: the use of alcohol and drugs is a social issue that constitutes serious problem for the health, with personal, family and social consequences. the present study is exploratory-descriptive nature and its objective was to evaluate the primary school as a predicting factor in the prevention of the consumption of the school and tobacco in students. interviews to students and professors were made by a pre-established guide, the results demonstrate that the 66,6% age is of 10 to 11 years. exposed to factors of risks associated to scholastic problems, low self- esteem and familiar problems. research shows that 15,6% have experienced alcohol and the 13,4% tobacco. the professors say that the children do not consume alcohol, tobacco or drugs, they say the children have conduct problems.
Pulmonary function tests in children Pruebas de función pulmonar en ni os
María de la luz Valencia Chávez
Iatreia , 1993,
Abstract: Pulmonary function tests are a valuable resource in the practice of pediatric neumology; they allow the establishment of syndromic diagnoses in obstructive or restrictive lung diseases of children; besides they are very useful in the follow-up of pediatric patients with asthma, cystic fibrosis or interstitial lung disease. In this article different diagnostic procedures are described; their bases, Interpretation and applications according to age are discussed. Las pruebas de función pulmonar son un recurso valioso e indispensable en neumología pediátrica, que ayuda a establecer diagnósticos de síndrome en las enfermedades pulmonares del ni o que tengan componentes obstructivos o restrictivos. Son también de gran utilidad en el seguimiento del ni o con asma, fibrosis quística o enfermedad intersticial. En este artículo se describen los diferentes procedimientos que se pueden practicar de acuerdo a la edad del ni o.
Costo-Efectividad de Instrumentos Económicos para el control de la contaminación: El Caso del Uso de Le?a
Chávez,Carlos; Gómez,Walter; Brice?o,Sandra;
Cuadernos de economía , 2009, DOI: 10.4067/S0717-68212009000200004
Abstract: we explore the cost-effectiveness of economic incentives to induce changes in wood consumption in urban areas. we consider the case of temuco and padre las casas in southern chile. three incentives schemes are considered: subsidy to the demand of dry wood, subsidy to the supply of dry wood, and enforcement of the standard on the humidity content of wood. the results suggest that subsidies should been targeted to the production of dry wood. the impacts on the aggregate level of emissions are small. finally, enforcing the humidity standard is more cost-effective than the evaluated subsidy programs.
Costo-Efectividad de Instrumentos Económicos para el control de la contaminación: El Caso del Uso de Le a
Carlos Chávez,Walter Gómez,Sandra Brice?o
Cuadernos de Economía , 2009,
Abstract: Exploramos la propiedad de costo-efectividad de utilizar incentivos para inducir cambios en los patrones de consumo de le a en zonas urbanas. Consideramos las comunas de Temuco y Padre Las Casas en el sur de Chile. Evaluamos tres sistemas de incentivos: subsidio a la demanda de le a seca, subsidio al secado de le a, y fiscalización de la norma sobre contenido de humedad de la le a comercializada. Los resultados sugieren orientar subsidios al secado de le a. El impacto sobre el nivel agregado de emisiones de material particulado es acotado. Finalmente, la fiscalización es más costo-efectiva que los programas de subsidio evaluados. We explore the cost-effectiveness of economic incentives to induce changes in wood consumption in urban areas. We consider the case of Temuco and Padre Las Casas in southern Chile. Three incentives schemes are considered: subsidy to the demand of dry wood, subsidy to the supply of dry wood, and enforcement of the standard on the humidity content of wood. The results suggest that subsidies should been targeted to the production of dry wood. The impacts on the aggregate level of emissions are small. Finally, enforcing the humidity standard is more cost-effective than the evaluated subsidy programs.
Degradation of Indigo Carmine Using Advanced Oxidation Processes: Synergy Effects and Toxicological Study  [PDF]
Elba Ortiz, Violeta Gómez-Chávez, Carlos M. Cortés-Romero, Hugo Solís, Rubén Ruiz-Ramos, Sandra Loera-Serna
Journal of Environmental Protection (JEP) , 2016, DOI: 10.4236/jep.2016.712137
Abstract:
The physicochemical degradation of Indigo Carmine (IC) dye in aqueous solution was performed using single and combined Advanced Oxidation Processes (AOP’s). Photocatalysis (TiO2-UV), Ozonation (O3) and Sonolysis (SN) were tested either in a standalone methodology or by combination of two simultaneous AOP’s. The dye conversion was followed by both measurements: 1) color removal determined by UV-VIS spectrometry and 2) organic and inorganic load determined by the chemical oxygen demand (COD). A complete and quick color disappearance of model water waste has been obtained by using combination of non-irradiated AOP’s, namely, O3/SN, which contrasts to the combination of irradiated photocatalysis with O3 or sonolysis. Color removal with simultaneous TiO2-UV/SN reached 77% while TiO2-UV/O3 reached 96% at similar reaction time. On the other hand, the standalone O3 yielded the highest color removal (94.4%) in 32 minutes whereas SN reached only 39.2% in 4 hours. The standalone light irradiated TiO2-UV reached 93.3% color re-moval in one hour of reaction time. These results indicated that non-irradiated (SN and O3) enhance synergistic effects that provoke structural changes in dye molecule without reaching total degradation. This is evidenced from FTIR of residuals from reaction mixture in which it has been observed the presence of organic molecules such as aromatics, sulfonic and amines refractory compounds that are mechanisti-cally possible to be found during IC degradation. Also, toxicity tests (MicroTox
Coniochaetidium zulianensis, a new record in the world
Delgado ávila,Adolfredo E; Urdaneta García,Lilia M; Pi?eiro Chávez,Albino J;
Revista Científica , 2008,
Abstract: on the basis of a study of coprophilous fungi from zulia state, venezuela, one specie of the family coniochaetaceae, with cleistothecial ascocarp and ascospores with germ pore was isolated from dove dung. it was identified as species of coniochaetidium malloch and cain. the species described in this paper differs from the other five (5) species in its morphological characteristic, globose asci, 8 spored and ellipsoidal ascospores, also this species differs from another by having larger ascopores, which are nearly double its length in culture. the species was identified as coniochaetidium zulianensis delgado, urdaneta and pi?eiro, which represents a new record in the world.
Coprotiella Venezuelensis, a new record of cleistothecia genus of the ascomycetes in the world
Delgado ávila,Adolfredo E; Urdaneta García,Lilia M; Pi?eiro Chávez,Albino J;
Revista Científica , 2009,
Abstract: a new record, coprotiella venezuelensis was isolate on rhinoceros dung collected at south park maracaibo zoo in zulia state, venezuela. the genus is compared with coprotus and c. gongylospora having ascospores possessing de bary bubbles.
Trastornos de coagulación en el cirrótico
Téllez-ávila, Felix I;Chávez-Tapia, Norberto C;Torre-Delgadillo, Aldo;
Revista de investigación clínica , 2007,
Abstract: the liver plays a central role in the clotting process. in this organ are sintetizated the major part of the coagulation factors. historically, was considered that alteration in liver function causes important bleeding disorders. however, actual evidence is not in agreement with this asseveration. decreased synthesis of clotting and inhibitor factors, decrease clearance of activated factors, quantitative and qualitative platelet defects, hyperfibrinolysis and intravascular coagulation are some of the defects observed in liver diseases. thrombotic events, even if rare in cirrhotic patients, occur manly in the portal and mesenteric veins. the aim of the present work is to review the present evidence in coagulation disorders and liver disease.
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