Estudio de la resistividad eléctrica de distintos papeles de impresión y escritura

Las propiedades eléctricas del papel tienen gran interés debido al amplio espectro de sus aplicaciones. En este trabajo se han utilizado varios tipos de papel, de fibra virgen y fibra reciclada, con el fin de comprobar si las propiedades eléctricas dependen de la composición fibrosa y el tratamiento al que se ha les ha sometido. La resistencia eléctrica se ha medido utilizando un dispositivo que consta de dos electros de geometría circular, entre los que se coloca el papel. A continuación se establece una diferencia de potencial y se determina directamente la resistencia eléctrica en distintas condiciones de humedad relativa. Se ha validado el método de medida utilizando papel de impresión de 80 g/m2, comprobándose que los valores obtenidos están dentro de los rangos que se indican en la bibliografía. Una vez que se conocen la resistencia eléctrica, el espesor del papel y la sección de los electrodos, se puede determinar la resistividad de los papeles. A partir de estos resultados se ha buscado una relación entre la resistividad y el contenido de humedad, utilizando diversos modelos de regresión cuya validez se analiza en el trabajo. Se ha analizado también la influencia de varias propiedades del papel, como la densidad aparente o el contenido de cenizas, discutiéndose la influencia de estas propiedades en la resistividad

Assessment of surf zone zooplankton dynamics in a Southwestern Atlantic sandy beach: Seasonal cycle and tidal height influence

Surf zones of sandy beaches are poorly studied in comparison to estuarine and continental shelf waters, specifically because of the difficulties experienced in sampling in high-energy environments. The zooplankton of these areas, therefore, has received less attention than that in other coastal systems. The aim of this study was to investigate the seasonal patterns and tidal height effects (high tide/low tide) on the surf zooplankton community in a temperate Southwestern Atlantic sandy beach. We also aimed to evaluate the influence of some environmental variables (water temperature, salinity, chlorophyll-a, suspended particulate matter and particulate organic carbon) on the community structure and to compare the surf community to nearby coastal zone (<to 50 m). Sampling was carried out from September 2009 to November 2010, with a monthly frequency during autumn-winter and bi-monthly during spring-summer.Fil: Menendez, Maria Clara. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Baleani, Carla Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Amodeo, Martín Raúl. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Acha, Eduardo Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de Investigación y Desarrollo Pesquero; ArgentinaFil: Piccolo, Maria Cintia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin

A randomized comparison of two anemia treatment regimens in Tanzanian children.

We used a prospective, open-label randomized trial to evaluate two treatment regimens in Tanzanian children two months to four years of age presenting to a hospital with a packed cell volume (PCV) < 25%. Treatment was either standard (14 days of ferrous sulfate and an antimalarial) or extended (three months of ferrous sulfate and three antimalarial treatments). The prevalence of anemia was measured two weeks after completion of treatment and six months after recruitment. Two weeks after completing treatment, the prevalence of PCV < 33% was 58% in the standard treatment arm and 44% in the extended treatment group (P = 0.04), and the mean PCV was significantly higher in the extended treatment arm (32.1%, SD = 4.5% versus 30.8%, SD = 4.9%; P = 0.031). However, there was no difference in the prevalence of PCV < 25% in the first survey, and the benefits of extended therapy were only apparent six months after recruitment in children compliant with the extended treatment (odds ratio of PCV < 25% = 0.16, P = 0.06). Compliance was satisfactory in only 39% (82 of 209) of the children in the first week of treatment. Extending the duration of therapy and improving compliance may have health benefits for anemic children in malaria-endemic settings

Spatial and temporal dynamics of the mesozooplankton (Crustacea: Cladocera, Copepoda and Decapoda) in a Pampean shallow hyposaline lake during drought conditions

La laguna Sauce Grande, un lago poco profundo, eutrófico e hiposalino, se estudió mediante muestreos mensuales entre diciembre de 2009 a noviembre de 2010. La sequía que afectó a la región desde 2009 y durante todo el período de estudio interrumpió la entrada regular del río y la salida al Océano Atlántico. La laguna presentó un aumento de los valores de salinidad y condiciones altamente turbias como resultado de las condiciones de sequía y de la resuspensión de sedimento por efecto del viento. Los cladóceros pequeños como Moina micrura y el copépodo Boeckella poopoensis dominaron la comunidad del mesozooplancton. La salinidad determinó la composición del mesozooplancton; mientras tanto, la dinámica de la abundancia estuvo determinada por la temperatura junto con las condiciones eutróficas durante el período de estudio. En un contexto global de cambio climático, y en una región donde la sequía y los ciclos húmedos son frecuentes, estos resultados contribuyen a comprender aún más los procesos que afectan la estructura y dinámica de la comunidad de zooplancton durante eventos climáticos extremos.The Sauce Grande Lake, a shallow, eutrophic and hyposaline lake, was studied through monthly samplings during a year (December 2009- November 2010). The drought that affected the region since 2009 and during the entire study period interrupted the regular inflow from the river and outflow to the Atlantic Ocean. The lake presented an increase of salinity values and highly turbid conditions as a result of drought conditions and wind resuspension. Small cladocerans as Moina micrura followed by the copepod Boeckella poopoensis dominates the mesozooplankton community. The salinity determined the mesozooplankton composition; meanwhile, the seasonal mesozooplankton abundance dynamic was ruled by temperature in conjunction with the eutrophic conditions during the study period. In a global context of climate change, and in a region where drought and wet cycles are frequent, these results further contribute to understanding the processes affecting the zooplankton community structure and dynamic during extreme climate events.Fil: Alfonso, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Baleani, Carla Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Menendez, Maria Clara. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Forneron, Claudia Fernanda. Instituto de Formación Docente Continua de Villa Regina; ArgentinaFil: Piccolo, Maria Cintia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Nacional del Sur. Departamento de Geografía y Turismo; Argentin

Afinidades morfológicas dos esqueletos do Holoceno inicial/ médio da América do Norte e América do Sul: uma contribuição para a dinâmica de expansão do cone sul

El objetivo de este trabajo es realizar un análisis comparativo de la morfología craneofacial en una muestra de 92 individuos del Holoceno temprano/medio proveniente de Sudamérica y Norteamérica con el propósito de discutir tanto la diversidad biológica presente en los individuos del Holoceno temprano del continente americano, así como las dinámicas de expansión ocurridas durante el Holoceno temprano y medio, utilizando técnicas de ordenamiento multivariado y cálculo de distancias biológicas. Nuestros resultados muestran una relativa estructuración geográfica entre las muestras del este y el oeste de Sudamérica, en la cual la muestra de Norteamérica se encuentra en una posición intermedia entre ambas con mayores similitudes con las muestras del oeste. Los individuos de las pampas argentinas presentan similitudes con los de Brasil, pero también con individuos de Chile y Colombia. Concluimos que la diversificación morfológica entre las poblaciones del este y oeste de Sudamérica se habría producido tempranamente, y algunas regiones como las pampas argentinas recibieron el aporte de distintos linajes ancestrales.The aim of this work is to carry out a comparative analysis of craniofacial morphology in a sample of 92 individuals from the early/middle Holocene from South and North America with the purpose of discussing both the biological diversity present in the early Holocene individuals from the American continent, as well as the expansion dynamics occurred during the early and middle Holocene, by using multivariate ordination techniques and calculating biological distances. Our results show a moderate geographic structure between the samples from eastern and western South America, in which the sample from North America is in an intermediate position between both, and presents larger similarities with the samples from the west. Individuals from the Argentine Pampas show similarities with those from Brazil but also with individuals from Chile and Colombia. We conclude that the morphological diversification between the populations of eastern and western South America occurred early, and some regions such as the Argentine Pampas received the contribution of different ancestral lineages.O objetivo deste trabalho é realizar uma análise comparativa da morfologia craniofacial em uma amostra de 92 indivíduos do Holoceno inicial e médio de América do Sul e América do Norte, a fim de discutir a diversidade biológica que apresentaram as primeiras populações em chegar ao continente, bem como as dinâmicas de expansão no decorrer do Holoceno inicial e médio, usando técnicas de ordenação multivariada e cálculo de distâncias biológicas. Nossos resultados mostram uma relativa estruturação geográfica entre as amostras do leste e oeste da América do Sul, na qual os indivíduos da América do Norte estão em uma posição intermediária entre as duas, ainda que com maiores semelhanças com as amostras ocidentais. Os indivíduos das pampas argentinas apresentam semelhanças com os de Brasil, mas também com os de Chile e Colômbia. Concluímos que a diversificação morfológica entre as populações do leste e oeste da América do Sul teria acontecido mais cedo, e algumas regiões como as pampas argentinas receberam a contribuição de diferentes linhagens ancestrais.Fil: Menendez, Lumila Paula. Universitaet Bonn. Institut Vii, Abteilung Altamerikanistik; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: López Sosa, María Clara. Universitaet Bonn. Institut Vii, Abteilung Altamerikanistik; AlemaniaFil: Solari, Ana. Instituto Nacional de Ciência e Tecnologia de Arqueologia, Paleontologia e Ambiente do Semiárido do Nordeste; Brasi

Varying efficacy of intermittent preventive treatment for malaria in infants in two similar trials: public health implications.

BACKGROUND\ud \ud Intermittent preventive treatment (IPTi) with sulphadoxine-pyrimethamine (SP) in infants resulted in different estimates of clinical malaria protection in two trials that used the same protocol in Ifakara, Tanzania, and Manhiça, Mozambique. Understanding the reasons for the discrepant results will help to elucidate the action mechanism of this intervention, which is essential for rational policy formulation.\ud \ud METHODS\ud \ud A comparative analysis of two IPTi trials that used the same study design, follow-up, intervention, procedures and assessment of outcomes, in Tanzania and Mozambique was undertaken. Children were randomised to receive either SP or placebo administered 3 times alongside routine vaccinations delivered through the Expanded Program on Immunisation (EPI). Characteristics of the two areas and efficacy on clinical malaria after each dose were compared.\ud \ud RESULTS\ud \ud The most relevant difference was in ITN's use ; 68% in Ifakara and zero in Manhiça. In Ifakara, IPTi was associated with a 53% (95% CI 14.0; 74.1) reduction in the risk of clinical malaria between the second and the third dose; during the same period there was no significant effect in Manhiça. Similarly, protection against malaria episodes was maintained in Ifakara during 6 months after dose 3, but no effect of IPTi was observed in Manhiça.\ud \ud CONCLUSION\ud \ud The high ITN coverage in Ifakara is the most likely explanation for the difference in IPTi efficacy on clinical malaria. Combination of IPTi and ITNs may be the most cost-effective tool for malaria control currently available, and needs to be explored in current and future studies.\ud \ud TRIAL REGISTRATION\ud \ud Manhiça study registration number: NCT00209795Ifakara study registration number: NCT88523834

Human ESCs predisposition to karyotypic instability: Is a matter of culture adaptation or differential vulnerability among hESC lines due to inherent properties?

<p>Abstract</p> <p>Background</p> <p>The use of human embryonic stem cells (hESCs) in research is increasing and hESCs hold the promise for many biological, clinical and toxicological studies. Human ESCs are expected to be chromosomally stable since karyotypic changes represent a pitfall for potential future applications. Recently, several studies have analysed the genomic stability of several hESC lines maintained after prolonged <it>in vitro </it>culture but controversial data has been reported. Here, we prompted to compare the chromosomal stability of three hESC lines maintained in the same laboratory using identical culture conditions and passaging methods.</p> <p>Results</p> <p>Molecular cytogenetic analyses performed in three different hESC lines maintained in parallel in identical culture conditions revealed significant differences among them in regard to their chromosomal integrity. In feeders, the HS181, SHEF-1 and SHEF-3 hESC lines were chromosomally stable up to 185 passages using either mechanical or enzymatic dissection methods. Despite the three hESC lines were maintained under identical conditions, each hESC line behaved differently upon being transferred to a feeder-free culture system. The two younger hESC lines, HS181 (71 passages) and SHEF-3 (51 passages) became chromosomally unstable shortly after being cultured in feeder-free conditions. The HS181 line gained a chromosome 12 by passage 17 and a marker by passage 21, characterized as a gain of chromosome 20 by SKY. Importantly, the mosaicism for trisomy 12 gradually increased up to 89% by passage 30, suggesting that this karyotypic abnormality provides a selective advantage. Similarly, the SHEF-3 line also acquired a trisomy of chromosome 14 as early as passage 10. However, this karyotypic aberration did not confer selective advantage to the genetically abnormal cells within the bulk culture and the level of mosaicism for the trisomy 14 remained overtime between 15%–36%. Strikingly, however, a much older hESC line, SHEF-1, which was maintained for 185 passages in feeders did not undergo any numerical or structural chromosomal change after 30 passages in feeder-free culture and over 215 passages in total.</p> <p>Conclusion</p> <p>These results support the concept that feeder-free conditions may partially contribute to hESC chromosomal changes but also confirm the hypothesis that regardless of the culture conditions, culture duration or splitting methods, some hESC lines are inherently more prone than others to karyotypic instability.</p

Pharmacokinetics of mefloquine and its effect on sulfamethoxazole and trimethoprim steady-state blood levels in intermittent preventive treatment (IPTp) of pregnant HIV-infected women in Kenya..

Abstract Background Intermittent preventive treatment in pregnancy with sulfadoxine/pyrimethamine is contra-indicated in HIV-positive pregnant women receiving sulfamethoxazole/trimethoprim prophylaxis. Since mefloquine is being considered as a replacement for sulfadoxine/pyrimethamine in this vulnerable population, an investigation on the pharmacokinetic interactions of mefloquine, sulfamethoxazole and trimethoprim in pregnant, HIV-infected women was performed. Methods A double-blinded, placebo-controlled study was conducted with 124 HIV-infected, pregnant women on a standard regimen of sulfamethoxazole/trimethoprim prophylaxis. Seventy-two subjects received three doses of mefloquine (15 mg/kg) at monthly intervals. Dried blood spots were collected from both placebo and mefloquine arms four to 672 h post-administration and on day 7 following a second monthly dose of mefloquine. A novel high-performance liquid chromatographic method was developed to simultaneously measure mefloquine, sulfamethoxazole and trimethoprim from each blood spot. Non-compartmental methods using a naïve-pooled data approach were used to determine mefloquine pharmacokinetic parameters. Results Sulfamethoxazole/trimethoprim prophylaxis did not noticeably influence mefloquine pharmacokinetics relative to reported values. The mefloquine half-life, observed clearance (CL/f), and area-under-the-curve (AUC0→∞) were 12.0 days, 0.035 l/h/kg and 431 µg-h/ml, respectively. Although trimethoprim steady-state levels were not significantly different between arms, sulfamethoxazole levels showed a significant 53 % decrease after mefloquine administration relative to the placebo group and returning to pre-dose levels at 28 days. Conclusions Although a transient decrease in sulfamethoxazole levels was observed, there was no change in hospital admissions due to secondary bacterial infections, implying that mefloquine may have provided antimicrobial protection

Morphometric affinities and direct radiocarbon dating of the Toca dos Coqueiros’ skull (Serra da Capivara, Brazil)

The biological variation of the earliest skeletons of South America has been intensely debated for the last two centuries. One of the major research constraints has been the limited number of available samples dating to the early Holocene. We here present the first direct radiocarbon-date for the early Holocene human skeleton from Toca dos Coqueiros (Serra da Capivara, Brazil), also known as “Zuzu” (8640 ± 30 BP; 9526–9681 cal years BP). We performed craniometric analyses using exclusively samples from Brazil, to revisit the sex of the skeleton, and to discuss the evolutionary processes involved in the occupation of the continent. The sex of the individual was estimated as a female when compared to late and early Holocene individuals, but as a male when compared only to the early Holocene series. We also found that Zuzu presents the strongest differences with the late Holocene Guajajara individuals, located nearby, and the strongest similarities with the early Holocene series from Lagoa Santa, attesting for solid biological affinities among early Holocene individuals from Brazil, as well as a moderate level of morphological variation among them. This suggests that the early individuals were part of the same heterogeneous lineage, possibly a different one from which late Holocene populations diverged.Fil: Menendez, Lumila Paula. Universidad de Viena; Austria. Universitat Bonn; AlemaniaFil: López Sosa, María Clara. Universitat Bonn; AlemaniaFil: Monteiro da Silva, Sergio Francisco Serafim. Universidade Federal de Pernambuco; BrasilFil: Martin, Gabriela. No especifíca;Fil: Pessis, Anne Marie. No especifíca;Fil: Guidon, Niède. No especifíca;Fil: Solari, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin