Vegetative Change on South Padre Island, Texas, over Twenty Years and Evaluation of Multispectral Videography in Determining Vegetative Cover and Species Identity

A comparative vegetation analysis of an island-wide transect of South Padre Island, Texas, was conducted in 1997 using aerial multispectral digital videography and line intercept ground truth techniques to assess the usefulness of videography in estimating vegetative cover and species identifications. Ground truth data were used to assess vegetative change occurring in the 20 years since the report of Judd et al. (1977) on the vegetation of South Padre Island. Estimates of total cover by ground truth and remote sensing techniques were similar (2.45% difference) on South Padre Island. Thus, airborne multispectral digital videography is an effective technique for assessing changes in total vegetative cover of Texas barrier islands. This technique will be an effective tool for documenting changes in total cover on barrier islands due to natural perturbations such as hurricanes and human disturbances including vehicular traffic. Imagery obtained at altitudes of 200 m or greater did not permit discrimination of dominant species in each of an island\u27s topographic zones. However, acquisition of imagery at a time of the year when dominant species are in specific phenological stages, such as flowering, and at a lower altitude may facilitate their recognition. Comparison of data from a single trans-island transect in 1997 with data from three trans-island transects and 18 transects across the foreshore, backshore, and primary dunes in 1977 suggests that there has been a marked decrease in species richness of the backshore and primary dune zones of South Padre Island. There also was a change in dominant species in the backshore zone. These changes in species richness and dominance may be largely attributable to vehicular traffic in these zones. - Un análisis comparativo de la vegetación de un transecto transinsular de la isla South Padre en el estado de Texas fue realizado en 1997 usando videografía aérea multiesprectral digital y técnicas de validación de intercepción linear terrestre para evaluar la utilidad de la videografía en la estimación de la cobertura vegetal e identificación de especies. Los datos de estudios de validación terrestre fueron utilizados para evaluar el cambio vegetativo que ocurrió durante 20 años después del informe de Judd et al (1977) sobre la vegetación de la isla South Padre. Las estimaciones de la cobertura total mediante técnicas de validación terrestres y de medición remota fueron similares (2.45% de diferencia) en la isla South Padre. Por lo tanto, la videografía multiesprectral digital aérea se considera una técnica eficaz para evaluar cambios en la cobertura vegetal de las islas barrera de Texas. Esta técnica será una herramienta efectiva para documentar los cambios de cobertura total en las islas barrera debido a las perturbaciones naturales tales como huracanes y disturbios humanos como tráfico vehicular. Las imágenes obtenidas en altitudes de 200 metros o mayores no permitieron la discriminación de las especies dominantes de las varias zonas topográficas de una isla. Sin embargo, la adquisición de imágenes de una época del año en que las especies dominantes están en etapas fenológicas específicas, tales como la floración, y desde una altitud menor, puede facilitar su reconocimiento. Al comparar datos de un transecto transinsular de 1977 con los de tres transectos transinsulares y de 18 transectos correspondientes a la parte frontal, trasera, y de las dunas primarias de la isla en 1977, se sugiere que ha habido una marcada disminución en la riqueza de especies en la parte trasera y en la zona de dunas primarias de la isla South Padre. También hubo un cambio de especies dominantes en la zona trasera. Estos cambios en la riqueza y dominancia de especies pueden ser atribuidos en gran parte al tráfico vehicular en estas zonas

Desarrollo de instrumentación virtual para uso en carreras de ingeniería

Las prácticas de laboratorio son una actividad indispensable en la formación integral de un estudiante de carreras tecnológicas. Bajo esta concepción, el equipo de trabajo que integra el proyecto, viene trabajando en el desarrollo tecnológico y pedagógico de instrumental de laboratorio que permita al estudiante “ver” lo que estudia mediante la construcción de los ensayos y el uso de una interfaz gráfica, como apoyo al proceso de visualizar señales y parámetros no visibles al ojo. Si bien originalmente se propuso la construcción de un “Laboratorio Portátil de Escritorio”, la pandemia del COVID-19, que impidió la realización de actividades educativas presenciales durante todo el año 2020 y posiblemente afecte a gran parte del año 2021, puso de manifiesto la importancia de disponer de instrumentación virtual, que permitan a nuestros estudiantes ser artífices de su propio aprendizaje, y realizar prácticas de laboratorio aun en sus hogares. Ante esta realidad, se consideró oportuno adaptar el proyecto original y, a partir del uso de software libre, encarar el desarrollo de instrumentos virtuales para que alumnos que cursan asignaturas de los primeros años de carreras de ingeniería o similares conozcan y aprendan a utilizar instrumental que luego usarán en asignaturas de años posterioresEje: Tecnología Informática aplicada en Educación.Red de Universidades con Carreras en Informátic

LANDSAT-2 Data for Inventorying Rangelands in South Texas

A 81,000-ha rangeland area in Kenedy and Willacy Counties, Texas, was used to test LANDSAT-2 MSS data from October 17 and December 10, 1975 for inventorying rangeland and various other land-use categories. Computer land-use classification percentages of land cover for each overpass were compared with photo-estimated percentages from a ground correlated 1:100,000 scale LANDSAT color composite print. We found a highly significant correlation (r = 0.977**) between the photo- and computer-estimated hectarages for the October LANDSAT-2 overpass. The correlation was not significant for the December overpass largely because about half of the most extensive rangeland category (mixed brush) was misclassified as grassland, probably because the woody species were dormant and freeze damage had weakened the herbaceous vegetation reflectance. Computer estimates of level I land-use (rangeland, wetland, agricultural land, water, and barren land) hectarage from both overpasses resembled photo-estimated hectarages, indicating the feasibility of estimating level I land-use categories in either October or December. Computer estimates of level II land-use (grasslands, mixed brush, and live oak rangelands) hectarages agreed with photo-estimated hectarages only in October, indicating that living vegetation is needed to spectrally discriminate between level II rangeland categories

Global spatial assessment of Aedes aegypti and Culex quinquefasciatus: A scenario of Zika virus exposure

Zika virus (ZIKV) is an arbovirus transmitted mainly by Aedes aegypti mosquitoes. Recent scientific evidence on Culex quinquefasciatus has suggested its potential as a vector for ZIKV, which may change the current risk zones. We aimed to quantify the world population potentially exposed to ZIKV in a spatially explicit way, considering the primary vector (A. aegypti) and the potential vector (C. quinquefasciatus). Our model combined species distribution modelling of mosquito species with spatially explicit human population data to estimate ZIKV exposure risk. We estimated the potential global distribution of C. quinquefasciatus and estimated its potential interaction zones with A. aegypti. Then we evaluated the risk zones for ZIKV considering both vectors. Finally, we quantified and compared the people under risk associated with each vector by risk level, country and continent. We found that C. quinquefasciatus had a more temperate distribution until 42° in both hemispheres, while the risk involving A. aegypti is concentrated mainly in tropical latitudes until 35° in both hemispheres. Globally, 4.2 billion people are under risk associated with ZIKV. Around 2.6 billon people are under very high risk associated with C. quinquefasciatus and 1 billion people associated with A. aegypti. Several countries could be exposed to ZIKV, which emphasises the need to clarify the competence of C. quinquefasciatus as a potential vector as soon as possible. The models presented here represent a tool for risk management, public health planning, mosquito control and preventive actions, especially to focus efforts on the most affected areas

Assessing habitat loss and fragmentation and their effects on population viability of forest specialist birds: linking biogeographical and population approaches

Aim: Biogeographic approaches usually have been developed apart from population ecology, resulting in predictive models without key parameters needed to account for reproductive and behavioural limitations on dispersal. Our aim was to incorporate fully spatially explicit population traits into a classic species distribution model (SDM) using Geographic Information Systems (GIS), aiming at conservation purposes. Location: Southern South America. Methods: Our analysis incorporates the effects of habitat loss and fragmentation on population viability and therefore provides insights into how much spatially explicit population traits can improve the SDM prediction of habitable habitat. We utilized a well-studied focal endemic bird of South American temperate rainforests (Scelorchilus rubecula). First, at a large scale, we assessed the historical extent habitat based on climate envelopes in an SDM. Second, we used a land cover change analysis at a regional scale to account for recent habitat loss and fragmentation. Third, we used empirically derived criteria to predict population responses to fragmented forest landscapes to identify actual losses of habitat and population. Then we selected three sites of high conservation value in southern Chile and applied our population model. Finally, we discuss the degree to which spatially explicit population traits can improve the SDM output without intervening in the modelling process itself. Results: We found a historical habitat loss of 39.12% and an additional forest cover loss of 3.03% during 2000-2014; the latter occurred with a high degree of fragmentation, reducing the overall estimation of (1) carrying capacity by -82.4%, -33.1% and -45.1% and (2) estimated number of pairs on viable populations by -84.1%, -33.0% and -54.6% on the three selected sites. Main conclusion: We conclude that our approach sharpened the SDM prediction on environmental suitability by 54.4%, adjusting the habitable area by adding population parameters through GIS, and allowing to incorporate other phenomena as fragmentation and habitat loss.Basal Found Project PBF-2

Habitat loss of a rainforest specialist pollinator fly as an indicator of conservation status of the South American temperate rainforests

We estimate habitat loss and fragmentation in a hoverfly, Aneriophora aureorufa, used as a representative forest specialist species. This species is a pollinator specialist of two native trees, forming a triad endemic to the South American Temperate Rainforest (SATR). We combine species distribution models with species-specific requirements to estimate the habitat range of A. aureorufa over two non-overlapping time periods (before human settlement to 2000, and from 2000 to 2014). We analyzed the predicted distribution range of A. aureorufa in Chile, quantifying habitat loss in both periods and fragmentation in the latter. In addition, we evaluated the representativeness of the Chilean protected areas system in relation to the current habitat of the species. We found that the total habitat of A. aureorufa decreased by 68.3% compared to historic pre-settlement levels; in the period 2000-2014 the loss was 4.9%. The northern zone was the most affected by habitat loss and fragmentation, with an estimated total loss of 89.9% from the historic period to 2014, with the loss of 238.2km(2) per year between 2000 and 2014. Eighteen percent of the habitat of A. aureorufa occurs within protected areas. We found an overrepresentation in the southern zone (24.79%) and an underrepresentation in the northern zone (3.44%). We propose that forest specialist species of the northern zone of the SATR could be threatened due to the high pressure of habitat loss and the underrepresentation of the Chilean protected areas systems

Gas Sensors Built with Nanomaterials and Provided with a Heating Double Purpose Hot-plate

Pure or doped SnO2, has been used to build resistive type gas sensors from several decades. This subject has been retaken using pure or doped nanocrystalline SnO2 to build the sensors, finding considerable advantages in devices performance. The sensors working temperature (Tw) decreases from (350-450) 0C to (180-200) 0C in comparison with that of devices built with microcrystalline conventional material. Sensitivity of sensors built with nanocrystalline material in comparison with that of devices built with conventional microcrystalline material, increases from 30 % to 37 %. In this work, SnO2 is synthesized using two different modified techniques based on gel-combustion and reactive oxidation and results of both syntheses are compared. Nanomaterials are characterised with X-ray diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and Field Emission Electron Scanning Microscopy (FESEM) and absorption techniques (BET). An electronic system, already patented by the authors, enables to alternatively measure the sensor resistivity (which is proportional to the adsorbed gas concentration) and set a constant working temperature, thus contributing to considerably save energy