221 research outputs found
A Bayesian framework for optimal motion planning with uncertainty
Modeling robot motion planning with uncertainty in a Bayesian framework leads to a computationally intractable stochastic control problem. We seek hypotheses that can justify a separate implementation of control, localization and planning. In the end, we reduce the stochastic control problem to path- planning in the extended space of poses x covariances; the transitions between states are modeled through the use of the Fisher information matrix. In this framework, we consider two problems: minimizing the execution time, and minimizing the final covariance, with an upper bound on the execution time. Two correct and complete algorithms are presented. The first is the direct extension of classical graph-search algorithms in the extended space. The second one is a back-projection algorithm: uncertainty constraints are propagated backward from the goal towards the start state
THE FARMHOUSES OF THE ROMAN COUNTRYSIDE: CENSUS AND CATALOG. THE CASE OF THE ESTATE OF FARNESIANA
Abstract. Rome is one of the cities with the largest green areas in the world, spread in villas and estates, within the municipal territory. But there is also a landscape triangle that radially branches out from the historic center, including a variety of unique situations (archaeological, historical – social, settlement, agriculture ...) in the world: the Caffarella and aqueducts Park. Inside, the Farnesiana estate, Capo di Bove, it's a witness of a widespread degradation process in the Roman countryside, which requires a gradual procedure of knowledge, cataloguing, restoration and re-functioning of the historical heritage. In this regard, the research is part of a larger study project of the Department of Architecture of Roma Tre, concerning farmhouses of the Roman countryside that deal with worrying degradation conditions and which require imminent intervention.</p
Rethinking High School: Preparing Students for Success in College, Career, and Life
Profiles Gates-supported programs providing a college-preparatory environment, strong academic programs, a coherent curriculum from junior high through high school, extra support during freshman year, and opportunities for dropouts to finish high school
Rethinking High School: Five Profiles of Innovative Models for Student Success
Examines the progress that has been made at five small schools across the U.S. that are representative of a growing network of more focused, academically rigorous high schools being developed to help students succeed in both high school and college
Electrically active defects in polycrystalline and single crystal metal halide perovskite
We studied electrically active defects in CsPbBr3 polycrystalline films and single crystals samples using the thermally stimulated currents (TSC) technique in the temperature range 100–400 K. Below room temperature, both polycrystalline and single-crystals TSC emission is composed by a quasi-continuum of energy levels in the range 0.1–0.3 eV, and capture cross sections ~10−21 cm2. Above room temperature, TSC analysis reveals the presence of defect states in the range 0.40–0.52 eV only in polycrystalline samples, whereas these intermediate energy states are absent in TSC detected in single crystals. In polycrystalline films, the occupancy changes of an energy level at 0.45 eV strongly influences the room temperature photoconductivity, giving rise to slow transients due to defect passivation. In single-crystals, where intermediate energy states are absent, the photoconductivity response during illumination is almost stable and characterized by fast rise/decay times, a promising result for future applications of this material in photodetection and dosimetry
Bioaccumulation of total mercury in the earthworm Eisenia andrei
Earthworms are a major part of the total biomass of soil fauna and play a vital role
in soil maintenance. They process large amounts of plant and soil material and can
accumulate many pollutants that may be present in the soil. Earthworms have been
explored as bioaccumulators for many heavy metal species such as Pb, Cu and Zn but
limited information is available for mercury uptake and bioaccumulation in earth-
worms and very few report on the factors that influence the kinetics of Hg uptake by
earthworms. It is known however that the uptake of Hg is strongly influenced by the
presence of organic matter, hence the influence of ligands are a major factor contribut
-
ing to the kinetics of mercury uptake in biosystems. In this work we have focused on
the uptake of mercury by earthworms (
Eisenia andrei
) in the presence of humic acid
(HA) under varying physical conditions of pH and temperature, done to assess the role
of humic acid in the bioaccumulation of mercury by earthworms from soils. The study
was conducted over a 5-day uptake period and all earthworm samples were analysed
by direct mercury analysis. Mercury distribution profiles as a function of time, bioac-
cumulation factors (BAFs), first order rate constants and body burden constants for
mercury uptake under selected conditions of temperature, pH as well as via the dermal
and gut route were evaluated in one comprehensive approach. The results showed
that the uptake of Hg was influenced by pH, temperature and the presence of HA.
Uptake of Hg
2
+
was improved at low pH and temperature when the earthworms in
soil were in contact with a saturating aqueous phase. The total amount of Hg
2
+
uptake
decreased from 75 to 48
% as a function of pH. For earthworms in dry soil, the uptake
was strongly influenced by the presence of the ligand. Calculated BAF values ranged
from 0.1 to 0.8. Mercury uptake typically followed first order kinetics with rate constants
determined as 0.2 to 1
h
?
1
.Scopus 201
Rethinking High School: Inaugural Graduations at New York City's New High Schools
Provides graduation and college acceptance rates at fourteen high schools established as part of New York City's 2002 new schools initiative. Reviews the new schools' goals and accomplishments in improving outcomes, such as offering advanced courses
Nature-Based Solutions Planning for Urban Microclimate Improvement and Health: An Integrated Ecological and Economic Approach
Nature-based Solutions (NbSs) play a pivotal role in mitigating the impact of microclimates on human well-being. The effectiveness of NbSs is contingent upon the synergy between natural capital, defined by the ecological structure and functions of the ecosystem, and human-derived capital, encompassing the economic investments required for implementation. This study introduces a decision-making framework designed to evaluate the impact of NbSs and advocate for optimal solutions for human health at the local scale, amalgamating ecological and economic assessments. Physiological Equivalent Temperature (PET) was chosen as a key urban parameter to assess the efficacy of NbSs in mitigating urban microclimates and enhancing human health. The PET analysis was conducted using ENVI-met 5.0.3 software across diverse urban scenarios in Gallipoli city, Italy. Integrated with a cost–benefit analysis of NbSs considering various investment scenarios, the study aimed to identify the most effective solution. Results indicated positive effects of NbSs in open spaces and around building blocks where the PET levels remained below 30 °C. Conversely, scenarios without NbSs exhibited PETs exceeding 40 °C, with peaks of 50 °C, posing potential risks to human health. Considering the social and economic benefits associated with PET mitigation, the cost–benefit analysis suggests that implementing NbSs using a mix of young and mature plants in the initial phase is advantageous compared to using only young plants. Thus, in establishing NbSs, it is crucial to consider not only the quantity of vegetation but also the strategic timing of implementation. In conclusion, our work offers an innovative framework that combines ecological and economic perspectives, providing valuable insights for decision-makers in urban planning and promoting the practical application of NbSs for enhanced human well-being
Palladium oxide nanoparticles: Preparation, characterization and catalytic activity evaluation
Stable palladium oxide nanoparticles were prepared in aqueous suspension with a very simple procedure, by dissolving palladium nitrate in water at a concentration around 10-4 M. UV-visible absorption spectroscopy was adopted to follow the formation of these nanoparticles, which were characterized by TEM microscopy, along with XRD, XPS and Raman measurements. DFT calculations allowed to interpret the Raman data and to clarify the species present at the surface of the nanoparticles. The catalytic activity of the latter was evaluated by monitoring the reduction of p-nitrophenol to p-aminophenol. This investigation paves the way to the use of these colloidal nanoparticles in processes of heterogeneous catalysis, in particular those concerning the catalytic degradation of aromatic derivatives that represent a serious danger for the environment as pollutants, as in the case of p-nitrophenol
Electrical and Optical Characterization of CsPbCl3 Films around the High-Temperature Phase Transitions
Large-area CsPbCl(3) films in the range 0.1–1.5 μm have been grown by radio frequency (RF)-magnetron sputtering on glass substrates by means of a one-step procedure. Three structural phase transitions have been detected, which are associated with hysteresis behavior in the electrical current when measured as a function of temperature in the range 295–330 K. Similarly, photoluminescence (PL) experiments in the same temperature range bring evidence of a non-monotonic shift of the PL peak. Detailed electrical characterizations evidenced how phase transitions are not influencing detrimentally the electrical transport properties of the films. In particular, the activation energy (0.6–0.8 eV) extracted from the temperature-dependent film resistivity does not appear to be correlated with phase changes. A non-linear trend of the photoconductivity response as a function of a ultra violet (UV) 365 nm light emitting diode (LED) power has been interpreted considering the presence of an exponential tail of intragap defects. Thermally stimulated currents after exposure with the same LED measured from room temperature up to 370 K showed no evidence of trapping effects due to intragap states on the electrical transport properties at room temperature of the films. As a consequence, measured photocurrents at room temperature appear to be well reproducible and stable in time, which are attractive features for possible future applications in photodetection
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