Carbon monoxide sensing properties of B-, Al- and Ga-doped Si nanowires.

Silicon nanowires (SiNWs) are considered as potential chemical sensors due to their large surface-to-volume ratio and their possible integration into arrays for nanotechnological applications. Detection of harmful gases like CO has been experimentally demonstrated, however, the influence of doping on the sensing capacity of SiNWs has not yet been reported. For this work, we theoretically studied the surface adsorption of a CO molecule on hydrogen-passivated SiNWs grown along the [111] crystallographic direction and compared it with the adsorption of other molecules such as NO, and O2. Three nanowire diameters and three dopant elements (B, Al and Ga) were considered, and calculations were done within the density functional theory framework. The results indicate that CO molecules are more strongly adsorbed on the doped SiNW than on the pristine SiNW. The following trend was observed for the CO adsorption energies: E A[B-doped] > E A[Al-doped] > E A[Ga-doped] > E A[undoped], for all diameters. The electronic charge transfers between the SiNWs and the adsorbed CO were estimated by using a Voronoi population analysis. The CO adsorbed onto the undoped SiNWs has an electron-acceptor character, while the CO adsorbed onto the B-, Al-, and Ga-doped SiNWs exhibits an electron-donor character. Comparing these results with the ones obtained for the NO and O2 adsorption, the larger CO adsorption energy on B-doped SiNWs indicates their good selectivity towards CO. These results suggest that SiNW-based sensors of toxic gases could represent a clear and advantageous application of nanotechnology in the improvement of human quality of life.

An assessment of commonly employed satellite-based remote sensors for mapping mangrove species in Mexico using an NDVI-based classification scheme.

Optimizing the classification accuracy of a mangrove forest is of utmost importance for conservation practitioners. Mangrove forest mapping using satellite-based remote sensing techniques is by far the most common method of classification currently used given the logistical difficulties of field endeavors in these forested wetlands. However, there is now an abundance of options from which to choose in regards to satellite sensors, which has led to substantially different estimations of mangrove forest location and extent with particular concern for degraded systems. The objective of this study was to assess the accuracy of mangrove forest classification using different remotely sensed data sources (i.e., Landsat-8, SPOT-5, Sentinel-2, and WorldView-2) for a system located along the Pacific coast of Mexico. Specifically, we examined a stressed semiarid mangrove forest which offers a variety of conditions such as dead areas, degraded stands, healthy mangroves, and very dense mangrove island formations. The results indicated that Landsat-8 (30 m per pixel) had  the lowest overall accuracy at 64% and that WorldView-2 (1.6 m per pixel) had the highest at 93%. Moreover, the SPOT-5 and the Sentinel-2 classifications (10 m per pixel) were very similar having accuracies of 75 and 78%, respectively. In comparison to WorldView-2, the other sensors overestimated the extent of Laguncularia racemosa and underestimated the extent of Rhizophora mangle. When considering such type of sensors, the higher spatial resolution can be particularly important in mapping small mangrove islands that often occur in degraded mangrove systems.

Assessing the influence of artificially constructed channels in the growth of afforested black mangrove (Avicennia germinans) within an arid coastal region.

Hypersaline conditions are common in sub-tropical latitudes where freshwater availability is seasonal. Hence, hydroperiod plays a crucial role in providing a suitable area for the establishment of new mangrove seedlings. The purpose of this study was to assess the function of hydrological change and irradiance in the growth of afforested black mangrove (Avicennia germinans) along the upper saltpan area by creating six channels of 1 m wide by 0.3 deep and 30 m length. All channels were constructed perpendicular to the main coastline of the Urias lagoon, Pacific coast of Mexico. Seedlings of black mangrove were planted along four of the channels. After ten months, the pore-water salinity concentration within the six channels was reduced by half. Results indicate that there were no significant differences (P > 0.05) in mangrove survival among the channels. However, the optimal growth of black mangroves was near the channels edge. The growth of mangrove seedlings planted under 50% of solar attenuation was 10 times higher as compared to mangroves under direct sunlight. This study shows the feasibility of using channels to enhance tidal flow and decrease hypersaline conditions for future afforestation endeavors in arid coastlines.

Nutrient removal in a closed silvofishery system using three mangrove species (Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle).

The removal of ammonium (NH4(+)), nitrite (NO2(-)), nitrate (NO3(-)), and phosphate (PO4(-3)) in a closed silvofishery system was examined using three mangrove species (i.e., Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle). Specifically, six closed tanks were installed for this experiment with a population of 60 Dormitator latifrons fishes per tank. We planted 40 seedlings in each of three experimental tanks separated by species, while the remaining tanks were used as control. During 15 weeks, nutrient concentrations among the three mangrove systems presented no significant differences (P>0.05). However, nutrient removal variability was minimum during the last 2-5 weeks. Mangroves presented an average efficiency of 63% for the removal of NH4(+) and NO2(-). Contrary, the average removal potential of NO3(-) and PO4(-3) was 50%. Results from this study suggest that the three mangrove species could be used in a closed silvofishery systems for the biological removal of NH4(+), NO2(-), NO3(-), and PO4(-3).

Evaluating the condition of a mangrove forest of the Mexican Pacific based on an estimated leaf area index mapping approach.

Given the alarming global rates of mangrove forest loss it is important that resource managers have access to updated information regarding both the extent and condition of their mangrove forests. Mexican mangroves in particular have been identified as experiencing an exceptional high annual rate of loss. However, conflicting studies, using remote sensing techniques, of the current state of many of these forests may be hindering all efforts to conserve and manage what remains. Focusing on one such system, the Teacapán-Agua Brava-Las Haciendas estuarine-mangrove complex of the Mexican Pacific, an attempt was made to develop a rapid method of mapping the current condition of the mangroves based on estimated LAI. Specifically, using an AccuPAR LP-80 Ceptometer, 300 indirect in situ LAI measurements were taken at various sites within the black mangrove (Avicennia germinans) dominated forests of the northern section of this system. From this sample, 225 measurements were then used to develop linear regression models based on their relationship with corresponding values derived from QuickBird very high resolution optical satellite data. Specifically, regression analyses of the in situ LAI with both the normalized difference vegetation index (NDVI) and the simple ration (SR) vegetation index revealed significant positive relationships [LAI versus NDVI (R (2) = 0.63); LAI versus SR (R (2) = 0.68)]. Moreover, using the remaining sample, further examination of standard errors and of an F test of the residual variances indicated little difference between the two models. Based on the NDVI model, a map of estimated mangrove LAI was then created. Excluding the dead mangrove areas (i.e. LAI = 0), which represented 40% of the total 30.4 km(2) of mangrove area identified in the scene, a mean estimated LAI value of 2.71 was recorded. By grouping the healthy fringe mangrove with the healthy riverine mangrove and by grouping the dwarf mangrove together with the poor condition mangrove, mean estimated LAI values of 4.66 and 2.39 were calculated, respectively. Given that the former healthy group only represents 8% of the total mangrove area examined, it is concluded that this mangrove system, considered one of the most important of the Pacific coast of the Americas, is currently experiencing a considerable state of degradation. Furthermore, based on the results of this investigation it is suggested that this approach could provide resource managers and scientists alike with a very rapid and effective method for monitoring the state of remaining mangrove forests of the Mexican Pacific and, possibly, other areas of the tropics.

[Eating habits in physical therapy students]. / Hábitos dietéticos en estudiantes de fisioterapia.

OBJECTIVE: a) To know the eating and exercising habits of undergraduate Physical Therapy students; b) To promote awareness among these future health professionals and educators of the need to foster adequate eating habits among patients and the general population. METHODS: A dietary and physical activity questionnaire, regarding a seven-day period, distributed among students of the School of Physical Therapy (University of Valladolid) in the city of Soria, Spain (n = 131; sex (m/f): 38/93). RESULTS: Results show that a high percentage of the subjects follow the recommendations of the new Nutritional Pyramid of the Spanish Nutrition Society (SEN) regarding intake of meat, fish, milk, dairy products and exercise habits. This is not the case, however, for products such as pasta, bread and cereals, vegetables, fruits, legumes and olive oil. Furthermore, fast food is taken, on average, once a week despite the recommended sporadic monthly intakes. CONCLUSIONS: According to results, formative programmes should be carried out to enable these students to encourage healthy diets. Thus, diseases related to non-healthy eating habits could be prevented, and information on the issue could be spread among the population.

[Prevalence of osteoporosis assessed by quantitative ultrasound calcaneus measurements in institutionalized elderly population]. / Prevalencia de osteoporosis en ancianos institucionalizados, mediante ultrasonografía de calcáneo.

OBJECTIVES: To analyze using quantitative ultrasound of calcaneus (QUS) the prevalence of osteoporosis in institutionalized elderly people, in order to contribute to state reliable criteria (T-score units) for the diagnosis of osteoporosis which allow advances in bone fracture prevention. MATERIAL AND METHODS: Elderly people (n=171) were divided into separate groups according to sex and age criteria (three decades, from 70 to 90 years) and analyzed using QUS. RESULTS: Both globally and in the younger groups, women showed significantly lower values than men in all densitometry variables (p < 0.001). In the oldest group only T-score and BUA showed statistical differences (p = 0.039 y p = 0.025, respectively). The prevalence of osteoporosis in women was higher than in men whichever criteria were applied in all age groups. Applying the WHO criteria with QUS, the prevalence of osteoporosis in global population is close to that stated by DEXA using the same criteria. CONCLUSIONS: QUS could be useful to assess the bone mass evolution with age and for the diagnosis and monitoring of osteoporosis. In our elderly population, the WHO criteria for DEXA, are also the most suitable ones for QUS utilization.

Ejercicio físico en el ancianoinstitucionalizado / Physical exercise in the institutionalized elderly

El objetivo fundamental en la atención al anciano es mejorar su salud, bienestar y calidad de vida. Desde nuestra perspectiva hemos confeccionado un programa de actividad física especialmente adaptado a las necesidades del anciano. Este programa deberá incluir los siguientes tipos de ejercicios: - 30-40 por ciento del programa para el trabajo aeróbico.- 30-40 por ciento para mejorar flexibilidad y fuerza.- 10 por ciento para mejorar el equilibrio.- 10 por ciento para mejorar coordinación.- 10 por ciento para mejorar velocidad de reacción (AU)