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Search Results: 1 - 10 of 3440 matches for " IRMA FUENTES "
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Temperature, energy acquisition and energy use in the Chilean silverside Basilichthys australis Eigenmann (Atherinopsidae)
FUENTES,LEOPOLDO; VILA,IRMA; CONTRERAS,MANUEL;
Revista chilena de historia natural , 2005, DOI: 10.4067/S0716-078X2005000200014
Abstract: we evaluated the influence of water temperature (tw) on the energy acquisition and use in the chilean silverside basilichthys australis (eigenmann 1927), an endemic species inhabiting freshwater ecosystems in chile. we tested the effect of tw (11.5, 14.0, 18.0, 22.0 and 26.0 °c) on food intake, digestibility, food transit time and metabolic rate. as expected, this study demonstrated that many physiological variables under study were significantly affected by tw, as well as the net energy balance of this species. nevertheless, the net energy balance was not strictly related to the range of tws evaluated. at tws lower than 14 °c the energy budget was depressed, because food intake was lower than at tws between 14 and 26 °c, where food intake was higher and independent of tw. consequently, at these temperatures the energy balance was positive and also independent of tw. physiologically, b. australis appears to be a tolerant species with respect to the wide range of water temperature in habitats at different depths. thus, its distributions may extend through the entire profile of lakes and rivers, even in systems characterised by spatial and temporal thermal variability
Temperature, energy acquisition and energy use in the Chilean silverside Basilichthys australis Eigenmann (Atherinopsidae) Temperatura, adquisición de energía y uso de energía en el pejerrey chileno Basilichthys australis Eigenmann (Atherinopsidae)
LEOPOLDO FUENTES,IRMA VILA,MANUEL CONTRERAS
Revista chilena de historia natural , 2005,
Abstract: We evaluated the influence of water temperature (Tw) on the energy acquisition and use in the chilean silverside Basilichthys australis (Eigenmann 1927), an endemic species inhabiting freshwater ecosystems in Chile. We tested the effect of Tw (11.5, 14.0, 18.0, 22.0 and 26.0 °C) on food intake, digestibility, food transit time and metabolic rate. As expected, this study demonstrated that many physiological variables under study were significantly affected by Tw, as well as the net energy balance of this species. Nevertheless, the net energy balance was not strictly related to the range of Tws evaluated. At Tws lower than 14 °C the energy budget was depressed, because food intake was lower than at Tws between 14 and 26 °C, where food intake was higher and independent of Tw. Consequently, at these temperatures the energy balance was positive and also independent of Tw. Physiologically, B. australis appears to be a tolerant species with respect to the wide range of water temperature in habitats at different depths. Thus, its distributions may extend through the entire profile of lakes and rivers, even in systems characterised by spatial and temporal thermal variability En este trabajo evaluamos la influencia de la temperatura del agua (Ta) en la adquisición de energía y su uso por parte del pejerrey chileno Basilichthys australis (Eigenmann 1927), una especie endémica que habita los ecosistemas dulceacuícolas de Chile. Investigamos el efecto de Ta (11,5, 14,0, 18,0, 22,0 y 26,0 °C) en la ingesta de alimento, digestibilidad, tiempo de transito del alimento y tasa metabólica. De acuerdo a lo esperado, este estudio demostró que varias de las variables fisiológicas bajo estudio fueron significativamente afectadas por Ta, así como el balance energético de esta especie. Sin embargo, el balance neto de energía no estuvo estrictamente relacionado al rango de Tas evaluadas. En Tas inferiores a 14 °C el presupuesto de energía fue deprimido, debido a que la ingesta de alimento fue inferior que en Tas entre 14 y 26 °C, donde la ingesta de alimento fue mayor e independiente de Ta. Consecuentemente, en estas temperaturas el balance de energía fue positivo y también independiente de Ta. Fisiológicamente, B. australis parece ser una especie tolerante en un amplio rango de temperaturas acuáticas en hábitats de diferentes profundidades. Así, su distribución puede extenderse a través del entero perfil vertical de lagos y ríos, aun en sistemas caracterizados por presentar variabilidad termal en las escalas espacial y temporal
Methamphetamine and male suicide in the US-Mexico border region  [PDF]
Elsa de J. Hernández Fuentes, Bernardo Ng, Irma A. González Hernández
Open Journal of Internal Medicine (OJIM) , 2013, DOI: 10.4236/ojim.2013.32007
Abstract:

Introduction: Studying the use of psychoactive substances in completed suicide is essential in order to understand its role in the suicide generating stimuli. The most commonly reported substances are alcohol and opioids. Method: This is a retrospective study of completed suicide database of the Forensics Medical office in the city of Mexicali from 1999 to 2005. This is the capital of the Mexican state of Baja California in the US-Mexico border region. Results: Out of 288 suicides, 260 were men, and the most frequent drug found on autopsy was methamphetamine (p < 0.001). The modal victim was a young male (20 - 39 years old), employed in blue-collar jobs, lived in an urban area, found in their homes, and died by hanging. Discussion: Although no causal effect can be drawn, our study results suggest that methamphetamine use may be a risk factor for suicide in this sample.

ELECTRICAL CONDUCTIVITY OF HYDROPHOBICALLY MODIFIED POLYELECTROLYTES IN METHANOL/WATER SOLUTION
BARRAZA,RAUL G.; OLEA,ANDRES F.; FUENTES,IRMA; MARTINEZ,FRANCISCO;
Journal of the Chilean Chemical Society , 2003, DOI: 10.4067/S0717-97072003000100012
Abstract: measurements of the electrical equivalent conductivity of potassium salts of poly(maleic acid-co-1-olefins), pa-nk2 with n = 12, 18 has been carried out in methanol-water mixtures in the whole range of composition. the relative interaction parameter f*, was determined as a function of the mole fraction of methanol. the values of f* do not follow the same tendency of the limiting equivalent conductivity. this unusual behavior was rationalized in terms of a methanol-induced conformational transition that takes the polymer chain from a compact to an expanded structure. as a consequence of this transition the average charge distance in the polyion increases with increasing mole fraction of methanol. this brings about a decrease of the linear charge density parameter, and therefore an increase of the fraction of polymer charges dissociated from their counterions. the existence of the conformational transition of the pa-nk2 copolymers was confirmed through fluorescence probing experiments
Muertes por violencia en las mujeres de Tijuana, Baja California, 1999-2005
David F. Fuentes Romero,Irma A. González Hernández
Papeles de población , 2008,
Abstract: En este artículo se analiza el perfil de las muertes violentas en las mujeres de Tijuana, Baja California. Los datos provienen de fuentes forense, hemerográfica y del análisis derivado de los expedientes de homicidios dolosos. Se encontró que el rango de edad con mayor frecuencia en los homicidios de mujeres se da entre los 20 y los 34 a os (42 por ciento). Sin embargo, en las mujeres el riesgo de morir víctima de un asesinato es más alto en menores de 15 a os (20 por ciento). Las formas y medios de mayor frecuencia para asesinar a las mujeres son: heridas por lesiones y golpes (42.3 por ciento), disparo con arma de fuego (28 por ciento), asfixia mecánica y herida por arma blanca (28.8 por ciento).
SELF-ASSEMBLY OF TRIBLOCK COPOLYMERS IN AQUEOUS SOLUTION
BRUNO URBANO,PATRICIO SILVA,ANDRéS F OLEA,IRMA FUENTES
Journal of the Chilean Chemical Society , 2008,
Abstract: The aggregation of PE4VP-b-PS-b-PE4VP block copolymers was studied in aqueous solution. Triblock copolymers P4VP-b-PS-b-P4VP were synthesized by sequential anionic polymerization of poly(styrene) and poly(4-vinylpirydine) using sodium naphthalene as a bifunctional initiator. Subsequently, the 4-vinylpyridine units were quaternized with ethyl bromide to obtain cationic PE4VP-b-PS-b-PE4VP block copolymers. Both star and crew-cut micelles were formed. The concentrations at which micelles are formed cmc were determined, by steady-state and time-resolved fluorescence probing methods, as a function of quatemization degree. The results indicate that cmc of crew-cut micelles increases with increasing charge density of the PE4VP blocks. For star micelles there is not a clear dependency of cmc with the percentage of quatemization. The lifetime of pyrene fluorescence and the ratio I1/I3 were determined at concentrations of copolymers well above the cmc, and the results show that the location of pyrene into the micelle changes with the charge density of the micelle corona. The micropolarity sensed by pyrene decreases with increasing quatemization degree. The presence of aggregates was confirmed by transmission electronic microscopy.
ELECTRICAL CONDUCTIVITY OF HYDROPHOBICALLY MODIFIED POLYELECTROLYTES IN METHANOL/WATER SOLUTION
RAUL G. BARRAZA,ANDRES F. OLEA,IRMA FUENTES,FRANCISCO MARTINEZ
Journal of the Chilean Chemical Society , 2003,
Abstract: Measurements of the electrical equivalent conductivity of potassium salts of poly(maleic acid-co-1-olefins), PA-nK2 with n = 12, 18 has been carried out in methanol-water mixtures in the whole range of composition. The relative interaction parameter f*, was determined as a function of the mole fraction of methanol. The values of f* do not follow the same tendency of the limiting equivalent conductivity. This unusual behavior was rationalized in terms of a methanol-induced conformational transition that takes the polymer chain from a compact to an expanded structure. As a consequence of this transition the average charge distance in the polyion increases with increasing mole fraction of methanol. This brings about a decrease of the linear charge density parameter, and therefore an increase of the fraction of polymer charges dissociated from their counterions. The existence of the conformational transition of the PA-nK2 copolymers was confirmed through fluorescence probing experiments
Compositional, Functional and Sensory Characteristics of Selected Mexican Cheeses  [PDF]
Irma Caro, Sergio Soto, Lucía Fuentes, Néstor Gutiérrez-Méndez, Briselda García-Islas, Karol E. Monroy-Gayosso, Javier Mateo
Food and Nutrition Sciences (FNS) , 2014, DOI: 10.4236/fns.2014.54044
Abstract:

The aim of this study was to describe the compositional, functional and sensory properties of six traditional Mexican cheeses: Panela, Oaxaca, Manchego, Manchego Botanero, Tenate, and Morral. A total of 50 cheeses were analysed. Relevant compositional parameters including pH, aw, proximate composition, NaCl, sugars, lactic and acetic acids, mineral contents, free-amino acid nitrogen, fat acid degree value and total fatty acids were determined. In addition, colour and texture profile analyses of unmelted cheeses and their meltability were investigated. Furthermore, other 30 cheeses were used for a descriptive sensory analysis. Properties of cheeses were described, compared between each cheese, and related to their respective making processes.

Chromosomes of Girella laevifrons (Tschudi 1846) (Osteichthyes: Kyphosidae)
Northland-Leppe,Irma; Véjar,Drina; Jara-Seguel,Pedro; Fuentes,Nelson; Nú?ez,Cristian;
Gayana (Concepción) , 2010, DOI: 10.4067/S0717-65382010000200007
Abstract: the chromosome number and karyotype morphology of girella laevifrons (tschudi 1846) are described for the first time. g. laevifrons presents a chromosome number of 2n = 48 and its karyotype is formed in both sexes by 24 acrocentric chromosome pairs, similar to what has been described for other species of girella gray, 1835.
SELF-ASSEMBLY OF TRIBLOCK COPOLYMERS IN AQUEOUS SOLUTION
URBANO,BRUNO; SILVA,PATRICIO; OLEA,ANDRéS F; FUENTES,IRMA; MARTINEZ,FRANCISCO;
Journal of the Chilean Chemical Society , 2008, DOI: 10.4067/S0717-97072008000200013
Abstract: the aggregation of pe4vp-b-ps-b-pe4vp block copolymers was studied in aqueous solution. triblock copolymers p4vp-b-ps-b-p4vp were synthesized by sequential anionic polymerization of poly(styrene) and poly(4-vinylpirydine) using sodium naphthalene as a bifunctional initiator. subsequently, the 4-vinylpyridine units were quaternized with ethyl bromide to obtain cationic pe4vp-b-ps-b-pe4vp block copolymers. both star and crew-cut micelles were formed. the concentrations at which micelles are formed cmc were determined, by steady-state and time-resolved fluorescence probing methods, as a function of quatemization degree. the results indicate that cmc of crew-cut micelles increases with increasing charge density of the pe4vp blocks. for star micelles there is not a clear dependency of cmc with the percentage of quatemization. the lifetime of pyrene fluorescence and the ratio i1/i3 were determined at concentrations of copolymers well above the cmc, and the results show that the location of pyrene into the micelle changes with the charge density of the micelle corona. the micropolarity sensed by pyrene decreases with increasing quatemization degree. the presence of aggregates was confirmed by transmission electronic microscopy.
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