100 research outputs found
Contribution of Phosphorylation Residues in the A4 Subunit to the α4β2 Neuronal Nachr Function and Expression
Processing of Nanosensors Using a Sacrificial Template Approach
A new microsensor fabrication approach has been demonstrated based upon the use of nanostructures as templates. The fundamental idea is that existing nanostructures, such as carbon nano tubes or biological structures, have a material structure that can be used advantageously in order to provide new sensor systems but lack the advantages of some materials to, for example, operate at high temperatures. The approach is to start with a template using nanostructures such as a carbon nanotube. This template can then be coated by an oxide material with higher temperature capabilities. Upon heating in air, the carbon nanotube template is burned off, leaving only the metal oxide nanostructure. The resulting structure has a combination of the crystal structure and surface morphology of the carbon nanotube, combined with the material durability and hightemperature- sensing properties of the metal oxide. Further, since the metal oxide nanocrystals are deposited on the carbon nanotube, after burn-off what is left is a metal oxide porous nanostructure. This makes both the interior and the exterior of this nano structured sensor available for gas species detection. This, in effect, increases the surface area available for sensing, which has been shown in the past to significantly increase sensor performance
Evaluación de la satisfacción de los turistas del Aeropuerto Internacional de Tocumen enfocado al traslado terrestre
Tocumen International Airport is the largest gateway for visitors to Panama for tourism. Therefore, the period of stay at the airport is a critical period which is part of the passenger travel experience. The main objective of the study is to evaluate the satisfaction of who arrive as tourists to Tocumen International Airport focusing on ground transportation to and from the airport; in order to find the gaps in service quality and to analyze it to improve the tourist experience. The methodology is based on gathering information, making surveys using Likert scales, interviews directly with tourists who have used or use transportation services for transportation to and from the airport, analysis of data and suggestions for improvements. Currently, there is no study evaluating the efficiency, safety, price, among other important things of transportation services that can be used by tourists to travel to and from Tocumen International Airport. Tourism is the most important economic activity and growth potential in Panama. This generates an increase in the activity of transfer of tourists; as well as a challenge in the experience and satisfaction in the quality of service available. A balance between price, security, availability and attention could greatly increase the perception in the quality of these available services with the help of airport authorities in order to standardize operational arrangements to integrate and maximize the satisfaction of tourists. The results were announced that the shuttle service to and from the International aAirport of Tocumen in reference to each of the variables studied have a greater tendency to good service, but there are about 20 % to 24 % with trends to poor service that need improvement.El Aeropuerto Internacional de Tocumen, es la mayor puerta de ingreso de los visitantes que llegan a Panamá por turismo. Por lo tanto, el
período de estancia en el aeropuerto es un período crítico que forma parte de la experiencia de viaje del pasajero. El principal objetivo del estudio es evaluar la satisfacción de los turistas, usuarios del Aeropuerto Internacional de Tocumen enfocado al traslado terrestre desde y hacia el aeropuerto; con el propósito de encontrar las brechas en la calidad de servicio y analizarlas para así mejorar la experiencia
del turista. La metodología empleada está basada en la recopilación de información, elaboración de encuestas empleando escalas Likert, entrevistas de forma directa con los turistas que hayan utilizado o que utilizarán los servicios de transporte para su traslado hacia y desde el aeropuerto, análisis de los datos obtenidos y propuestas de mejoras. En la actualidad, no existe un estudio de la valoración de la eficiencia, seguridad, precio, entre otros aspectos importantes de los servicios de transporte que pueden ser utilizados por los turistas para trasladarse desde y hacia el Aeropuerto Internacional de Tocumen.
El turismo es la actividad económica de mayor relevancia y potencial crecimiento en Panamá. Esto genera un crecimiento en la actividad de traslado de turistas; así como un desafío en la experiencia y satisfacción en la calidad de servicio de traslado. Un equilibrio entre precio, seguridad, disponibilidad y atención podría incrementar enormemente la percepción en la calidad de estos servicios con la ayuda de autoridades aeroportuarias con el fin de estandarizar gestiones operativas que permitan integrar y maximizar la satisfacción de los turistas.
Los resultados dieron a conocer que los servicios de traslados desde y hacia el Aeropuerto Internacional de Tocumen en referencia a cada una de las variables estudiadas poseen una mayor tendencia a un buen servicio, sin embargo hay alrededor de un 20% a 24% con tendencias a un mal servicio que necesitan ser mejoras
Development of a Batch Fabrication Process for Chemical Nanosensors: Recent Advancements at NASA Glenn Research Center
A major objective in aerospace sensor development is to produce sensors that are small in size, easy to batch fabricate and low in cost, and have low power consumption. Chemical sensors involving nanostructured materials can provide these characteristics as well as the potential for the development of sensor systems with unique properties and improved performance. However, the fabrication and processing of nanostructures for sensor applications currently is limited by the ability to control their location on the sensor platform, which in turn hinders the progress for batch fabrication. This presentation will discuss the following: the development of a novel room temperature methane (CH4) sensor fabricated using porous tin oxide (SnO2) nanorods as the sensing material, the advantages of using nanomaterials in sensor designs, the challenges encountered with the integration of nanostructures into microsensordevices, and the different methods that have been attempted to address these challenges. An approach for the mass production of sensors with nanostructures using a method developed by our group at the NASA Glenn Research Center to control the alignment of nanostructures onto a sensor platform will also be described
Impacto Económico de los Tratados de Libre Comercio en el Estado Social de Derecho de Colombia
Aunque la apertura comercial entre Estados promete grandes ventajas en la exportación e importación de productos permitiendo a los países alcanzar el desarrollo, no es viable está política liberal en un Estado Social de Derecho donde prima las necesidades sociales por encima de la capitalización del mercado, no, sin la capacitación y la infraestructura adecuada del mercado nacional.
Para poder comprender esta discusión es necesario establecer los alcances que tiene un Estado Social de Derecho como Colombia, en que se fundamenta la “soberanía alimentaria” o soberanía social de un estado de derecho, seguidamente se realizara un resumen de los TLC vigentes en Colombia y a la misma medida se presentara una evolución de algunos de ellos, por último, analiza el panorama del mercado internacional regional conforme a la implantación de los TLC con Estados Unidos (EE. UU.), de esta forma se espera poder comprender el impacto de los TLC en el mercado local de los estados y como se afecta su soberanía nacional después de su implementación
Integration of Nanostructures into Microsensor Devices on Whole Wafers
Chemical sensors are used in a wide variety of applications, such as environmental monitoring, fire detection, emission monitoring, and health monitoring. The fabrication of chemical sensors involving nanostructured materials holds the potential for the development of sensor systems with unique properties and improved performance. However, the fabrication and processing of nanostructures for sensor applications currently are limited in the ability to control their location on the sensor, which in turn hinders the progress for batch fabrication. This report discusses the advantages of using nanomaterials in sensor designs, some of the challenges encountered with the integration of nanostructures into microsensor / devices, and then briefly describes different methods attempted by other groups to address this issue. Finally, this report will describe how our approach for the controlled alignment of nanostructures onto a sensor platform was applied to demonstrate an approach for the mass production of sensors with nanostructures
Guided Data Augmentation for Offline Reinforcement Learning and Imitation Learning
Learning from demonstration (LfD) is a popular technique that uses expert
demonstrations to learn robot control policies. However, the difficulty in
acquiring expert-quality demonstrations limits the applicability of LfD
methods: real-world data collection is often costly, and the quality of the
demonstrations depends greatly on the demonstrator's abilities and safety
concerns. A number of works have leveraged data augmentation (DA) to
inexpensively generate additional demonstration data, but most DA works
generate augmented data in a random fashion and ultimately produce highly
suboptimal data. In this work, we propose Guided Data Augmentation (GuDA), a
human-guided DA framework that generates expert-quality augmented data. The key
insight of GuDA is that while it may be difficult to demonstrate the sequence
of actions required to produce expert data, a user can often easily identify
when an augmented trajectory segment represents task progress. Thus, the user
can impose a series of simple rules on the DA process to automatically generate
augmented samples that approximate expert behavior. To extract a policy from
GuDA, we use off-the-shelf offline reinforcement learning and behavior cloning
algorithms. We evaluate GuDA on a physical robot soccer task as well as
simulated D4RL navigation tasks, a simulated autonomous driving task, and a
simulated soccer task. Empirically, we find that GuDA enables learning from a
small set of potentially suboptimal demonstrations and substantially
outperforms a DA strategy that samples augmented data randomly
Seasonal patterns of estuarine acidification in seagrass beds of the Snohomish Estuary, WA
Recent studies have begun to explore physical and biogeochemical mechanisms of carbonate chemistry variability in a variety of coastal habitats, including coral reefs, upwelling margins, and inland seas. To our knowledge, there have been limited mechanistic studies of annual carbonate chemistry variability in nearshore estuarine environments. Here, we present autonomous sensor and grab sample data of carbonate chemistry covering a 10 month period from two subtidal seagrass bed sites in Possession Sound, WA. Simple mass balance stoichiometric models are used to evaluate seasonal drivers of carbonate system parameters in the seagrass beds. Simulations of increasing anthropogenic carbon (Canth) burdens in the habitats reveal seasonal differences in the magnitude of carbonate system responses. The addition of Canth alters the thermodynamic buffer factors (e.g. the Revelle factor) of the carbonate system, decreasing the system’s ability to buffer natural variability in the seagrass habitat on high-frequency (e.g. tidal, diel) and seasonal timescales. As a result, the most harmful carbonate system indices for many estuarine organisms (minimum pHT, minimum Ωarag, and maximum pCO2(s.w.)) change most rapidly with increasing Canth. We highlight how the observed seasonal climatology and non-linear response of the carbonate system to increasing Canth drive the timing of the crossing of established physiological stress thresholds for endemic organisms, as well as thresholds relevant for water quality management. In this system, the relative benefits of the seagrass beds in locally mitigating ocean acidification during the growing season increase with the higher atmospheric CO2 levels predicted toward 2100. Presently however, these mitigating effects are mixed due to intense diel cycling of CO2 driven by community metabolism
The Fox and the Hound: Zeus’s Paradox and Prioritizing Ecosystem Recovery
In Greek mythology, Zeus solves the paradox of the giant Teumessian fox, which had the power to never be caught, and Laelaps, the magical hound that always caught its prey, by changing them into constellations (Canis major and Canis minor) where their battle could play out for eternity. Zeus’s paradox also aptly describes the play of politics and science in prioritizing ecosystem recovery actions. Faced with the problem of prioritizing across hundreds of actions identified to recover terrestrial, freshwater, and nearshore domains of the Puget Sound, we structured an interactive process to capture both the key socio-political values of decision makers and expert knowledge about ecological effectiveness. Decision makers identified four important values for prioritization: ecological outcomes, strategic outcomes, protection of tribal treaty rights, and implementation issues. At their direction we decomposed the first two into 27 attributes. Technical experts nominated by decision makers evaluated 74 suites of recovery actions proposed for terrestrial, freshwater, and nearshore ecoystems by the attributes. We used a multi-attribute utility theory model with attribute weights developed with the decision makers to rank the 74 suites of recovery actions. Highest ranked were suites of actions focused on protecting ecosystem structure and functions and on balancing the need to accommodate population growth with ecosystem stressors imposed by development
Puget Sound Dissolved Oxygen Modeling Study: Development of an Intermediate-Scale Hydrodynamic Model
The Washington State Department of Ecology contracted with Pacific Northwest National Laboratory to develop an intermediate-scale hydrodynamic and water quality model to study dissolved oxygen and nutrient dynamics in Puget Sound and to help define potential Puget Sound-wide nutrient management strategies and decisions. Specifically, the project is expected to help determine 1) if current and potential future nitrogen loadings from point and non-point sources are significantly impairing water quality at a large scale and 2) what level of nutrient reductions are necessary to reduce or dominate human impacts to dissolved oxygen levels in the sensitive areas. In this study, an intermediate-scale hydrodynamic model of Puget Sound was developed to simulate the hydrodynamics of Puget Sound and the Northwest Straits for the year 2006. The model was constructed using the unstructured Finite Volume Coastal Ocean Model. The overall model grid resolution within Puget Sound in its present configuration is about 880 m. The model was driven by tides, river inflows, and meteorological forcing (wind and net heat flux) and simulated tidal circulations, temperature, and salinity distributions in Puget Sound. The model was validated against observed data of water surface elevation, velocity, temperature, and salinity at various stations within the study domain. Model validation indicated that the model simulates tidal elevations and currents in Puget Sound well and reproduces the general patterns of the temperature and salinity distributions
- …