Primer registro fósil del gasterópodo Cincinnatia (Hydrobiidae: Nymphophilinae) en México

Se describe el primer registro en México de conchas fósiles del gasterópodo de aguas continentales del género Cincinnatia Pilsbry, 1891, encontrados en sedimentos fluviátiles del Pleistoceno tardío en el valle de Acatita, Coahuila. La morfología y el análisis discriminante de las conchas indican que el material fósil corresponde a Cincinnatia integra (Say, 1821), una especie reciente con una distribución disjunta entre la parte oriental de los EUA y sur de Canadá y un área pequena˜ en la cuenca del río Pánuco, San Luís Potosí, México. Los nuevos hallazgos marcan el límite más occidental de la distribución original del género Cincinnatia y sugieren una conexión entre ambas áreas norte-sur en la extensión original de C. integra, hoy separadas, según registros, por más de 700 km, desde el Pleistoceno tardío hasta tiempos subrecientes. Considerando que el norte de México es hasta la fecha una región poco muestreada con referencia a los miembros de la familia Hydrobiidae, existe una alta probabilidad de hallazgos de poblaciones vivas de Cincinnatia en las cuencas altas de esta región así como en sitios acuáticos de la parte norte de los estados de Coahuila, Nuevo León y Tamaulipas. ABSTRAC The first record of fossil shells of the freshwater gastropod genus Cincinnatia Pilsbry, 1891 found in fluvial sediments of the late Pleistocene in the Acatita Valley, Coahuila, Mexico, is described. Morphology and discriminant analysisindicate that the fossil material correspond to Cincinnatia integra (Say, 1821), an extant species with a disjunct distribution between the eastern part of United States of America and southern Canada and a small area near Pánuco River, San Luis Potosí, Mexico. The new findings mark the westernmost limit of the original distribution of Cincinnatia and suggest a north-south connection between both areas in the original extension of C. integra, today separated according to the records by more than 700 km, since the late Pleistocene to sub-recent times. Considering that northern Mexico to date is under-sampled for the Hydrobiidae, there is a high probability of finding live populations of Cincinnatia in this region and in other aquatic habitats in the northern part of the states of Coahuila, Nuevo León, and Tamaulipas

Graphene Derivatives: Controlled Properties, Nanocomposites, and Energy Harvesting Applications

Graphene is a ground‐breaking two‐dimensional (2D) material that possesses outstanding electrical, optical, thermal, and mechanical properties and that promises a new generation of devices. Despite all these, some applications require graphene‐based materials with different characteristics, such as good solubility in organic solvents and a specific band gap to be dispersible in polymer nanocomposite matrix and applied as active layer, electron transport layer (ETL) or hole transport layer (HTL) in organic photovoltaics. Chemically modified graphene derivatives are studied, searching for better dispersions and even more properties for different applications. Most of the attention has been drawn to dispersions of graphene oxides or highly reduced graphene oxides. Therefore, this allows an opportunity to study the characteristics of materials with intermediate oxidation degrees and its applications

Análisis del nicho climático de Coryphantha durangensis (Runge ex Schum.) Britton y Rose, 1923 e identificación de zonas potenciales para su conservación ante el cambio climático

Coryphantha durangensis it is an endemic cactus that lives in Mexico, in the center of the Chihuahuan desert, and is considered as Special Protection by the NOM-059-SEMARNAT-2010 One of the greatest threats to this species is climate change and habitat loss. In the present study, the climatic niche of C. durangensis was evaluated and the habitat availability of this species was modeled using the MaxEnt algorithm under current climate conditions and future. The results show a reduction in the geographical areas that present climatically suitable conditions for the presence of this species for the year 2050 and 2070, however, four sites were identified that could be proposed as conservation areas for this and other species that cohabit in these zones.Coryphantha durangensis es una cactácea endémica que habita en México, en el centro del desierto Chihuahuense, y está considerada en la categoría de Protección Especial por la NOM-059-SEMARNAT-2010. Una de las mayores amenazas para esta especie es el cambio climático y pérdida de idoneidad climática para su presencia, en el presente estudio se evaluó el nicho climático de C. durangensis y se modeló la disponibilidad climática de esta especie mediante el algoritmo MaxEnt bajo condiciones del clima actual y futuro. Los resultados muestran una reducción en las zonas geográficas que presentan condiciones climáticamente adecuadas para la presencia de esta especie para el año 2050 y 2070. Sin embargo, se identificaron cuatro sitios que podrían ser propuestos como áreas de conservación para ésta y otras especies que cohabitan en estas zonas

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Algunos aspectos sobre el nodrizaje en Astrophytum myriostigma Lem. (1839) (Cactae: Cactaceae), en la Sierra El Sarnoso, Durango, México

"La condición de nodrizaje es una estrategia de plantas de zonas áridas, radica en que los propágulos se establecen bajo plantas o rocas (consideradas nodrizas), obteniendo los beneficios de disminución de la temperatura, aumento de la cantidad de nutrientes, protección contra depredadores, daños mecánicos, radiación solar, heladas, etc. Se fijaron tres objetivos: 1) Determinar la densidad de especies que utiliza como nodrizas Astrophytum myriostigma Lem. en una población de la sierra El Sarnoso, 2) Inferir cuales nodrizas están asociadas significativamente con A. myriostigma y 3) Calcular estadísticamente el vigor de asociación de A. myriostigma con las especies vegetales asociadas. El estudio se realizó en la sierra El Sarnoso, municipio de Lerdo, Durango, México, donde se establecieron cuadrantes de 10 x 10 m, se determinó el porcentaje de nodrizaje para las distintas especies que A. myriostigma utiliza como nodriza. Posteriormente se calculó el índice de asociación de x2 de Kendall, con tablas de contingencia para dos especies (presencia/ausencia). La magnitud de la asociación se determinó con el coeficiente de correlación r Pearson. Como resultados se obtuvo que Agave lechuguilla Torr. fue la única especie que tuvo una asociación significativa y muy estrecha junto con las covariables Opuntia rufida Lehm. y Jatropha dioica Torr. con una correlación altamente significativa, con un nivel de confianza de 95 %. Como conclusiones se tiene que A. myriostigma aprovecha la presencia de la mayoría de las especies vegetales como nodrizas en el área, en especial tres especies, sin embargo posee una gran especificidad de asociación con A. lechuguilla.

Effect of climate change on halophytic grasslands loss and its impact in the viability of Gopherus flavomarginatus

The decrease of the habitat is one of the main factors that affect the survival of G. flavomarginatus. This study assesses the halophytic grasslands loss over a period of 30 years in the distribution area of the Bolson tortoise and the effects of climate change on the habitat suitability of these grasslands and its possible impact on this tortoise. Grassland loss was assessed by an analysis of symmetric differences and the habitat suitability model was carried out by the method of overlapping layers raster. Our results showed a grassland loss of 63.7%; however, our current habitat suitability model points out that much of the grassland loss has occurred where the environmental conditions are suitable. These results suggest that anthropic activity is a main factor in the habitat disturbance in the study area. Likewise, the models for years 2050 and 2070 under the criteria RCP 2.6, RCP 4.5, RCP 6.0, suggest that anthropic activity will continue be the main cause of the grassland loss. Therefore, considering the association between the Bolson tortoise and grassland halophyte Hilaria mutica, which comprises around 60% of its diet, the viability of the Bolson tortoise depends largely on strategies aimed at protecting the soil that allow the presence of this grassland