Structure and electronic properties of molybdenum monoatomic wires encapsulated in carbon nanotubes

Monoatomic chains of molybdenum encapsulated in single walled carbon nanotubes of different chiralities are investigated using density functional theory. We determine the optimal size of the carbon nanotube for encapsulating a single atomic wire, as well as the most stable atomic arrangement adopted by the wire. We also study the transport properties in the ballistic regime by computing the transmission coefficients and tracing them back to electronic conduction channels of the wire and the host. We predict that carbon nanotubes of appropriate radii encapsulating a Mo wire have metallic behavior, even if both the nanotube and the wire are insulators. Therefore, encapsulating Mo wires in CNT is a way to create conductive quasi one-dimensional hybrid nanostructures.Comment: 8 pages, 10 figure

Impact of dimerization and stretching on the transport properties of molybdenum atomic wires

We study the electrical and transport properties of monoatomic Mo wires with different structural characteristics. We consider first periodic wires with inter-atomic distances ranging between the dimerized wire to that formed by equidistant atoms. We find that the dimerized case has a gap in the electronic structure which makes it insulating, as opposed to the equidistant or near-equidistant cases which are metallic. We also simulate two conducting one-dimensional Mo electrodes separated by a scattering region which contains a number of dimers between 1 and 6. The $I-V$ characteristics strongly depend on the number of dimers and vary from ohmic to tunneling, with the presence of different gaps. We also find that stretched chains are ferromagnetic.Comment: 8 pages, 7 figure

Variaciones en las características de las aguas del río Negro (Provincia del Chaco, Argentina) desde sus nacientes hasta su desembocadura

Los ríos tienen un rol importante en el desarrollo de múltiples procesos que ocurren sobre la superficie terrestre. A largo de su recorrido, producen reacciones que afectan a su entorno. Así, la interacción del agua de los ríos con el terreno que atraviesan, definen en gran parte las características hidroquímicas y geoquímicas de los cuerpos de agua, que hacen posible o no la vida.En este trabajo se ha muestreado espacial y temporalmente las variables físicas y químicas de las aguas del río Negro (Provincia del Chaco, Argentina), a fin de evaluar las fuentes que producen sus variaciones: precipitaciones, suelos e influencia antrópica. Se ha evaluado además la influencia de la hidroquímica sobre el comportamiento de los sólidos suspendidos. De esta forma se espera contribuir con el conocimiento sobre la dinámica de las aguas de éste río de llanura y echar luz sobre el efecto de la actividad antrópica sobre ella

Introducción al estudio de sedimentos fluviales de llanura

Con la finalidad de conservar los ambientes fluviales en sus condiciones prístinas, diversas variables deben ser analizadas. Los sedimentos son unas de las variables más importantes dado que influye potencialmente la morfología del paisaje, la química de las aguas y la dinámica biológica de los cursos de agua. El presente trabajo presenta una introducción de fácil interpretación sobre las características de mayor relevancia ambiental de los sedimentos, sus interacciones y su dinámica en áreas de llanura, de tal modo que los científicos que trabajen en ambientes fluviales de llanura puedan tener una primera aproximación para una correcta interpretación ambiental del rol de los sedimentos. Las características aquí mencionadas incluyen clasificación granulométrica, transporte y mineralogía. En las últimas décadas aumentaron las investigaciones sobre estudios orientados a la evaluación de ambientes fluviales con el objeto de mejorar el conocimiento de su estructura y dinámica, para así poder trabajar en mantenerlos lo más cercano posible a sus condiciones prístinas, mediante una correcta gestión de los recursos involucrados.En el presente trabajo se realiza una breve introducción a los fundamentos que rigen el estudio de los sedimentos en ambientes fluviales de llanura, una de las variablesa tener en cuenta, junto a las características físicas y químicas de las aguas, así como de los suelos, cuando se pretende realizar un estudio del estado y evolución de un ambiente. Una correcta interpretación de los ambientes de llanura resulta indispensable para los científicos que trabajan en la región, dado que la Llanura Chacopampeana y la región Mesopotámica, son áreas caracterizadas por la baja pendiente.

Neural correlates of phonological, orthographic and semantic reading processing in dyslexia

Developmental dyslexia is one of the most prevalent learning disabilities, thought to be associated with dysfunction in the neural systems underlying typical reading acquisition. Neuroimaging research has shown that readers with dyslexia exhibit regional hypoactivation in left hemisphere reading nodes, relative to control counterparts. This evidence, however, comes from studies that have focused only on isolated aspects of reading. The present study aims to characterize left hemisphere regional hypoactivation in readers with dyslexia for the main processes involved in successful reading: phonological, orthographic and semantic. Forty-one participants performed a demanding reading task during MRI scanning. Results showed that readers with dyslexia exhibited hypoactivation associated with phonological processing in parietal regions; with orthographic processing in parietal regions, Broca's area, ventral occipitotemporal cortex and thalamus; and with semantic processing in angular gyrus and hippocampus. Stronger functional connectivity was observed for readers with dyslexia than for control readers 1) between the thalamus and the inferior parietal cortex/ventral occipitotemporal cortex during pseudoword reading; and, 2) between the hippocampus and the pars opercularis during word reading. These findings constitute the strongest evidence to date for the interplay between regional hypoactivation and functional connectivity in the main processes supporting reading in dyslexia. Keywords: Dyslexia, Reading, Hypoactivation, Functional connectivity, Thalamus, Hippocampu

Genome-wide association study to identify genomic regions and positional candidate genes associated with male fertility in beef cattle

[EN] Fertility plays a key role in the success of calf production, but there is evidence that reproductive efficiency in beef cattle has decreased during the past half-century worldwide. Therefore, identifying animals with superior fertility could significantly impact cow-calf production efficiency. The objective of this research was to identify candidate regions affecting bull fertility in beef cattle and positional candidate genes annotated within these regions. A GWAS using a weighted single-step genomic BLUP approach was performed on 265 crossbred beef bulls to identify markers associated with scrotal circumference (SC) and sperm motility (SM). Eight windows containing 32 positional candidate genes and five windows containing 28 positional candidate genes explained more than 1% of the genetic variance for SC and SM, respectively. These windows were selected to perform gene annotation, QTL enrichment, and functional analyses. Functional candidate gene prioritization analysis revealed 14 prioritized candidate genes for SC of which MAP3K1 and VIP were previously found to play roles in male fertility. A different set of 14 prioritized genes were identified for SM and five were previously identified as regulators of male fertility (SOD2, TCP1, PACRG, SPEF2, PRLR). Significant enrichment results were identified for fertility and body conformation QTLs within the candidate windows. Gene ontology enrichment analysis including biological processes, molecular functions, and cellular components revealed significant GO terms associated with male fertility. The identification of these regions contributes to a better understanding of fertility associated traits and facilitates the discovery of positional candidate genes for future investigation of causal mutations and their implications.SIThe authors acknowledge financial support from the (FDE.13.17) Sustainable Beef and Forage Science Cluster funded by the Canadian Beef Cattle Check-Off, Beef Cattle Research Council (BCRC), Alberta Beef Producers, Alberta Cattle Feeders’ Association, Beef Farmers of Ontario, La Fédération des Productuers de bovins du Québec, and Agriculture and Agri-Food Canada’s Canadian Agricultural Partnership. This study was also supported by the Ontario Ministry of Agriculture, Food, and Rural Affairs (OMAFRA), Ontario Ministry of Research and Innovation, Agriculture and Agri-Food Canada (AAFC), and Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant. Hannah Sweett was supported by the OMAFRA Highly Qualified Personnel Scholarship Program

Transient-Receptor Potential (TRP) and Acid-Sensing Ion Channels (ASICs) in the Sensory Organs of Adult Zebrafish

Sensory information from the aquatic environment is required for life and survival of zebrafish. Changes in the environment are detected by specialized sensory cells that convert different types of stimuli into electric energy, thus originating an organ-specific transduction. Ion channels are at the basis of each sensory modality and are responsible or are required for detecting thermal, chemical, or mechanical stimuli but also for more complex sensory processes as hearing, olfaction, taste, or vision. The capacity of the sensory cells to preferentially detect a specific stimulus is the result of a characteristic combination of different ion channels. This chapter summarizes the current knowledge about the occurrence and localization of ion channels in sensory organs of zebrafish belonging to the superfamilies of transient-receptor potential and acid-sensing ion channels that are involved in different qualities of sensibility superfamilies in the sensory organs of zebrafish. This animal model is currently used to study some human pathologies in which ion channels are involved. Furthermore, zebrafish is regarded as an ideal model to study in vivo the transient-receptor potential ion channels

Luxación traumática de la rodilla

La luxación traumática de la rodilla es la lesión poco frecuente que se asocia a grandes lesiones cápsuloligamentosas y que a menudo afecta a estructuras neurológicas y vasculares. La lesión vascular es la complicación más importante. Todos los autores coinciden en que el diagnóstico precoz y tratamiento urgente de las lesiones de la arteria poplítea son esenciales. Sin embargo, no existe el mismo acuerdo en cuanto al tratamiento de las lesiones cápsuloligamentosas. Algunos autores publican buenos resultados con tratamientos no quirúrgicos, aunque otros consideran que el mejor tratamiento es la reparación completa de las lesiones ligamentosas. Hemos tratado en nuestro hospital siete casos de luxación traumática de rodilla en los últimos 20 años. Presentamos el tratamiento realizado, sus complicaciones y resultados.Traumatic knee dislocation is an uncommon injury associated with extensive soft tissue damage and often neurovascular involvement. Vascular injury is the most serious complication. There is genera agreement that early diagnosis and immediate treatment of popliteal artery disruption is essential. However there is no consensus about treatment of capsular and ligamentous injuries. Some authors reported good results advocated the repair of all ligaments in the best method. Seven traumatic knee dislocations have been treated in our hospital for last 20 years. Initial treatment, complications and results are presented

Nerve and Muscle Changes in the Upper Airways of Subjects with Obstructive Sleep Apnea: Structural Basis for the Neurogenic Theory

Obstructive sleep apnea syndrome (OSAS) is a widely diffused disease associated with specific genetics, age, gender, craniofacial and upper airways anatomy, obesity, and endocrine conditions, but not with ethnicity profiles. The so‐called neurogenic neurogenic theory of OSAS postulates that the collapse of the upper airways that characterize this disease is due to peripheral nerve degeneration that leads to muscle atrophy and collapse. This review attempts to summarize the structural and functional changes in both the sensory and motor innervation of the walls of the upper air ways in patients suffering from OSAS