375 research outputs found
Consumption habits and humps : [Version 23 June 2013]
We show that the optimal consumption of an individual over the life cycle can have the hump shape (inverted U-shape) observed empirically if the preferences of the individual exhibit internal habit formation. In the absence of habit formation, an impatient individual would prefer a decreasing consumption path over life. However, because of habit formation, a high initial consumption would lead to high required consumption in the future. To cover the future required consumption, wealth is set aside, but the necessary amount decreases with age which allows consumption to increase in the early part of life. At some age, the impatience outweighs the habit concerns so that consumption starts to decrease. We derive the optimal consumption strategy in closed form, deduce sufficient conditions for the presence of a consumption hump, and characterize the age at which the hump occurs. Numerical examples illustrate our findings. We show that our model calibrates well to U.S. consumption data from the Consumer Expenditure Survey
Great Location: About Effects of Surface Bound Neighboring Groups for Passive and Active Fine-Tuning of CO2 Adsorption Properties in Model Carbon Capture Materials
Improved carbon capture materials are crucial for managing the CO2 level in the atmosphere. The past focus was on increasing adsorption capacities. It is widely known that controlling the heat of adsorption (ΔHads) is equally important. If it is too low, CO2 uptake takes place at unfavorable conditions and with insufficient selectivity. If it is too high, chemisorption occurs, and the materials can hardly be regenerated. The conventional approach for influencing ΔHads is the modification of the adsorbing center. This paper proposes an alternative strategy. The hypothesis is that fine-tuning of the molecular environment around the adsorbing center is a powerful tool for the adjustment of CO2-binding properties. Via click chemistry, any desired neighboring group (NG) can be incorporated on the surfaces of the nanoporous organosilica model materials. Passive NGs induce a change in the polarity of the surface, whereas active NGs are capable of direct interaction with the active center/CO2 pair. The effects on ΔHads and on the selectivity are studied. A situation can be realized which resembles frustrated Lewis acid–base pairs, and the investigation of the binding-species by solid-state NMR indicates that the push–pull effects could play an essential role not only in CO2 adsorption but also in its activation. © 2021 The Authors. Advanced Materials published by Wiley-VCH Gmb
Small coastal marine protected areas offer recurring, seasonal protection to the common stingray (Dasyatis pastinaca)
Marine protected areas (MPAs) are a crucial tool in safeguarding marine biodiversity. However, elasmobranchs are often not the primary protection target of MPAs, and their contribution to protect these species remains to be better understood. In this study we examine the movement patterns of common stingrays in the Professor Luiz Saldanha marine park, a Portuguese temperate coastal MPA. Using acoustic telemetry, we tagged 31 common stingrays and analyzed their spatial and temporal distribution within the MPA and adjacent areas using a long-term data set. Our findings indicate that this species exhibits seasonal site fidelity, with greater presence during the colder months and reduced presence during warmer months. Space use areas did not exceed the size of the fully protected area, and nocturnal and crepuscular activity was significantly higher than during daytime. Additionally, we observed that most individuals seasonally migrated between this MPA and the nearby Sado estuary, likely to reproduce in the latter. These results demonstrate the site fidelity of common stingrays to an area within the marine park, however the protection provided is only seasonal. Seasonal protection of the movement corridor between the marine park and the estuary would improve the management of this species.La Caixa FoundationLCF/BQ/DI20/11780001, Fundacao para a Ciencia e a Tecnologia (FCT) POSEUR-03-2215-FC-000047info:eu-repo/semantics/publishedVersio
Bose-Einstein condensation of alkaline earth atoms: {Ca}
We have achieved Bose-Einstein condensation of Ca, the first for an
alkaline earth element. The influence of elastic and inelastic collisions
associated with the large ground state s-wave scattering length of Ca
was measured. From these findings, an optimized loading and cooling scheme was
developed that allowed us to condense about atoms after laser
cooling in a two-stage magneto-optical trap and subsequent forced evaporation
in a crossed dipole trap within less than 3 s. The condensation of an alkaline
earth element opens novel opportunities for precision measurements on the
narrow intercombination lines as well as investigations of molecular states at
the S--P asymptotes
Genetic analysis as a tool to improve the monitoring of stranded cetaceans in Chile
Cetacean strandings are regularly recorded along the coast of Chile. However, crucial information such as species and sex of the individuals involved in these events can often be difficult to assess. In this context, the use of molecular tools as a complementary method can improve a stranding database, particularly by correcting misidentifications and providing new data for unidentified samples. This new information is especially important in the case of species that are poorly known or of high conservation interest. In this study, we evaluate how molecular tools can support and complement the field work records of strandings in Chile by identifying, corroborating, or correcting the identification of the species and sex of the recorded individuals. We obtained samples through a collaboration with the government agency that is in charge of assisting with cetacean strandings and collected the relevant information. Multidisciplinary approaches like this, and inter-institutional collaborations, can improve the study of cetacean strandings and the decisions in management and conservation policies around them.
Cetacean strandings are a valuable source of information for several studies from species richness to conservation and management. During the examination of strandings, taxonomic and sex identification might be hindered for several reasons. Molecular techniques are valuable tools to obtain that missing information. This study evaluates how gene fragment amplification protocols can support the records of strandings done in the field in Chile by identifying, corroborating, or correcting the identification of the species and sex of the recorded individuals. Through a collaboration between a scientific laboratory and government institution in Chile, 63 samples were analyzed. Thirty-nine samples were successfully identified to the species level. In total, 17 species of six families were detected, including six species of conservation interest. Of the 39 samples, 29 corresponded to corroborations of field identifications. Seven corresponded to unidentified samples and three to corrected misidentifications, adding up to 28% of the identified samples. Sex was successfully identified for 58 of the 63 individuals. Twenty were corroborations, 34 were previously unidentified, and four were corrections. Applying this method improves the stranding database of Chile and provides new data for future management and conservation tasks.LA/P/0101/2020info:eu-repo/semantics/publishedVersio
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OntoKin: An Ontology for Chemical Kinetic Reaction Mechanisms.
An ontology for capturing both data and the semantics of chemical kinetic reaction mechanisms has been developed. Such mechanisms can be applied to simulate and understand the behavior of chemical processes, for example, the emission of pollutants from internal combustion engines. An ontology development methodology was used to produce the semantic model of the mechanisms, and a tool was developed to automate the assertion process. As part of the development methodology, the ontology is formally represented using a web ontology language (OWL), assessed by domain experts, and validated by applying a reasoning tool. The resulting ontology, termed OntoKin, has been used to represent example mechanisms from the literature. OntoKin and its instantiations are integrated to create a knowledge base (KB), which is deployed using the RDF4J triple store. The use of the OntoKin ontology and the KB is demonstrated for three use cases-querying across mechanisms, modeling atmospheric pollution dispersion, and as a mechanism browser tool. As part of the query use case, the OntoKin tools have been applied by a chemist to identify variations in the rate of a prompt NOx formation reaction in the combustion of ammonia as represented by four mechanisms in the literature
Case study: Near real-time thermal mapping to support firefighting and crisis management
Hot and dry summers have led to an increase in forest fires both concerning num-bers and intensity in north-eastern Germany in the last years. In the project FireSense the German Aerospace Center (DLR) has adapted its sensor system MACS (Modular Airborne Camera System) with a set of thermal mid- and long wave infrared (MWIR and LWIR) cam-eras to detect, monitor and quantify high temperature events (HTE) like forest fires. Ground-based, airborne and spaceborne measurements over fire-experiments are synchronized for cross-validation of the systems and to test the developed workflows. In summer 2019 gas flaring tests were conducted in cooperation of DLR and the Federal In-stitute for Material Research and Testing (BAM), parallel several large forest fires in Bran-denburg (Lieberose) and Mecklenburg-Vorpommern (Lübtheen) developed. In coordination with the crisis management group (local authorities, firefighters, armed forces, federal po-lice) to get the permits MACS conducted 3 flights over the fires in altitudes between 6000 (sunny) down to 3500 ft (under clouds), Lübtheen was covered twice, on July 2 and July 4, when the fire was already under control. Synchronously firefighting helicopters operated close to ground, also delivering videos of the fires for visual interpretation. To get both background temperatures for orientation and landscape features and also infor-mation about the fires within one data set, a broad calibration range for the LWIR camera was commanded. Using synchronized position- and orientation data of MACS with given calibration data and a Digital Terrain Model, direct geocoding and the processing of near real-time mosaics was possible using the DLR workflow even without post-processing. The accuracy was sufficient for planning purposes. Geo-tiff maps were delivered shortly after landing within less than three hours. The real-time capabilities of the system could not be used as the flights were conducted on very short notice and the radio link was not installed. The thermal data were delivered as false color heat maps. They show the thermal anomalies very well, clearly discriminating burning area, recently burnt area and unaffected forest. In the RGB data the ground fires are rarely visible as they are covered by and almost did not affect the closely standing crowns. The spread of the fires can be seen in the overlapping re-gions of adjacent flight lines. Data exchange and use of the data proved to be difficult due to limited data rates and IT in-frastructure in the command and situation center in the field, sometimes taking more time than the acquisition and processing. This reduces the practical benefit for the data in the field. For future planned experiments for real-time mapping of forest fires this will be one of the main points to improve the latency of the data transfer to the control center ideally by us-ing a live data link and to optimize the coordination with the control center. Further activi-ties will be coordinated by the Helmholtz Innovation Lab OPTSAL (Optische Technologien für Situationserfassung im Sicherheitsbereich), which was started at DLR in 2020. In OPTSAL hard- and software solutions are developed and activities concerning situational awareness for safety and security are coordinated with industry and authorities
Perspectives of Ultra Cold Atoms Trapped in Magnetic Micro Potentials
Recent work on magnetic micro traps for ultracold atoms is briefly reviewed.
The basic principles of operation are described together with the loading
methods and some of the realized trap geometries. Experiments are discussed
that study the interaction between atoms and the surface of micro traps as well
as the dynamics of ultracold gases in wave guides are discussed. The results
allow for an outlook towards future directions of research
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An Ontology and Semantic Web Service for Quantum Chemistry Calculations.
The purpose of this article is to present an ontology, termed OntoCompChem, for quantum chemistry calculations as performed by the Gaussian quantum chemistry software, as well as a semantic web service named MolHub. The OntoCompChem ontology has been developed based on the semantics of concepts specified in the CompChem convention of Chemical Markup Language (CML) and by extending the Gainesville Core (GNVC) ontology. MolHub is developed in order to establish semantic interoperability between different tools used in quantum chemistry and thermochemistry calculations, and as such is integrated into the J-Park Simulator (JPS)-a multidomain interactive simulation platform and expert system. It uses the OntoCompChem ontology and implements a formal language based on propositional logic as a part of its query engine, which verifies satisfiability through reasoning. This paper also presents a NASA polynomial use-case scenario to demonstrate semantic interoperability between Gaussian and a tool for thermodynamic data calculations within MolHub.This project is supported by the National Research Foundation (NRF), Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme, and by the Alexander von Humboldt foundation
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