76 research outputs found
Proxy dynamic delegation in grid gateway
Nowadays one of the main obstacles the research comes up against is the
difficulty in accessing the required computational resources. Grid is able to
offer the user a wide set of resources, even if they are often too hard to
exploit for non expert end user. Use simplification has today become a common
practice in the access and utilization of Cloud, Grid, and data center
resources. With the launch of L-GRID gateway, we introduced a new way to deal
with Grid portals. L-GRID is an extremely light portal developed in order to
access the EGI Grid infrastructure via Web, allowing users to submit their jobs
from whatever Web browser in a few minutes, without any knowledge about the
underlying Grid infrastructure.Comment: 6 page
Quantifying the Plasmonic Character of Optical Excitations in a Molecular J-Aggregate
The definition of plasmon at the microscopic scale is far from being
understood. Yet, it is very important to recognize plasmonic features in
optical excitations, as they can inspire new applications and trigger new
discoveries by analogy with the rich phenomenology of metal nanoparticle
plasmons. Recently, the concepts of plasmonicity index and the generalized
plasmonicity index (GPI) have been devised as computational tools to quantify
the plasmonic nature of optical excitations. The question may arise whether any
strong absorption band, possibly with some sort of collective character in its
microscopic origin, shares the status of plasmon. Here we demonstrate that this
is not always the case, by considering a well-known class of systems
represented by J-aggregates molecular crystals, characterized by the intense J
band of absorption. By means of first-principles simulations, based on a
many-body perturbation theory formalism, we investigate the optical properties
of a J-aggregate made of push-pull organic dyes. We show that the effect of
aggregation is to lower the GPI associated with the J-band with respect to the
isolated dye one, which corresponds to a nonplasmonic character of the
electronic excitations. In order to rationalize our finding, we then propose a
simplified one-dimensional theoretical model of the J-aggregate. A useful
microscopic picture of what discriminates a collective molecular crystal
excitation from a plasmon is eventually obtained.Comment: Published by ACS under ACS AuthorChoice licens
Interplay between Intra- and Intermolecular Charge Transfer in the Optical Excitations of J-Aggregates
In a first-principles study based on density functional theory and many-body
perturbation theory, we address the interplay between intra- and intermolecular
interactions in a J-aggregate formed by push-pull organic dyes by investigating
its electronic and optical properties. We find that the most intense excitation
dominating the spectral onset of the aggregate, i.e., the J-band, exhibits a
combination of intramolecular charge transfer, coming from the push-pull
character of the constituting dyes, and intermolecular charge transfer, due to
the dense molecular packing. We also show the presence of a pure intermolecular
charge-transfer excitation within the J-band, which is expected to play a
relevant role in the emission properties of the J-aggregate. Our results shed
light on the microscopic character of optical excitations of J-aggregates and
offer new perspectives to further understand the nature of collective
excitations in organic semiconductors.Comment: published under ACS Authorchoice licens
The Anatomy of a Grid portal
In this paper we introduce a new way to deal with Grid portals referring to
our implementation. L-GRID is a light portal to access the EGEE/EGI Grid
infrastructure via Web, allowing users to submit their jobs from a common Web
browser in a few minutes, without any knowledge about the Grid infrastructure.
It provides the control over the complete lifecycle of a Grid Job, from its
submission and status monitoring, to the output retrieval. The system,
implemented as client-server architecture, is based on the Globus Grid
middleware. The client side application is based on a java applet; the server
relies on a Globus User Interface. There is no need of user registration on the
server side, and the user needs only his own X.509 personal certificate. The
system is user-friendly, secure (it uses SSL protocol, mechanism for dynamic
delegation and identity creation in public key infrastructures), highly
customizable, open source, and easy to install. The X.509 personal certificate
does not get out from the local machine. It allows to reduce the time spent for
the job submission, granting at the same time a higher efficiency and a better
security level in proxy delegation and management.Comment: 6 page
Device‐to‐Materials Pathway for Electron Traps Detection in Amorphous GeSe‐Based Selectors
The choice of the ideal material employed in selector devices is a tough task both from the theoretical and experimental side, especially due to the lack of a synergistic approach between techniques able to correlate specific material properties with device characteristics. Using a material-to-device multiscale technique, we propose a reliable protocol for an efficient characterization of the active traps in amorphous GeSe chalcogenide. The resulting trap maps trace back the specific features of materials responsible for the measured findings, and connect them to an atomistic description of the sample. Our metrological approach can be straightforwardly extended to other materials and devices, which is very beneficial for an efficient material-device co-design and the optimization of novel technologies
Tendências neoliberais nas reformas e no financiamento do ensino superior brasileiro no início do século XXI
Este artigo tem como objetivo analisar os impactos das reformas e do financiamento da educação superior no Brasil, principalmente no século XXI em âmbito federal, de forma a traçar um breve panorama sobre este nível educacional a partir da implementação histórica de políticas neoliberais recomendadas por organismos internacionais. Nosso corpus de dados foi obtido a partir das seguintes fontes: Sinopses Estatísticas da Educação Superior (INEP); Produto Interno Bruto (PIB) disponibilizado pelo IBGE; o painel do orçamento do Sistema Integrado de Planejamento e Orçamento (SIOP); e Indicadores Financeiros Educacionais elaborados pelo INEP. A análise do conjunto de resultados, considerando o número de matrículas e ingressantes e os investimentos em programas de expansão, permitiu evidenciar a aceleração da ampliação do setor privado - universidades de ensino - e a continuidade das políticas neoliberais ao longo do século XXI na educação superior brasileira pública - universidades de pesquisa
Calibration and assessment of electrochemical low-cost sensors in remote alpine harsh environments
This work presents results from an original open-source low-cost sensor (LCS) system developed to measure tropospheric O3 in a remote high altitude alpine site. Our study was conducted at the Col Margherita Observatory (2543 m above sea level), in the Italian Eastern Alps. The sensor system mounts three commercial low-cost O3/NO2 sensors that have been calibrated before field deployment against a laboratory standard (Thermo Scientific; 49i-PS), calibrated against the standard reference photometer no. 15 calibration scale of the World Meteorological Organization (WMO). Intra- and intercomparison between the sensors and a reference instrument (Thermo Scientific; 49c) have been conducted for 7 months from May to December 2018. The sensors required an individual calibration, both in laboratory and in the field. The sensor's dependence on the environmental meteorological variables has been considered and discussed. We showed that it is possible to reduce the bias of one LCS by using the average coefficient values of another LCS working in tandem, suggesting a way forward for the development of remote field calibration techniques. We showed that it is possible reconstruct the environmental ozone concentration during the loss of reference instrument data in situations caused by power outages. The evaluation of the analytical performances of this sensing system provides a limit of detection (LOD) 0.8, bias >3.5 ppb and ±8.5 at 95 % confidence. This first implementation of a LCS system in an alpine remote location demonstrated how to obtain valuable data from a low-cost instrument in a remote environment, opening new perspectives for the adoption of low-cost sensor networks in atmospheric sciences.publishedVersio
Off-label long acting injectable antipsychotics in real-world clinical practice: a cross-sectional analysis of prescriptive patterns from the STAR Network DEPOT study
Introduction Information on the off-label use of Long-Acting Injectable (LAI) antipsychotics in the real world is lacking. In this study, we aimed to identify the sociodemographic and clinical features of patients treated with on- vs off-label LAIs and predictors of off-label First- or Second-Generation Antipsychotic (FGA vs. SGA) LAI choice in everyday clinical practice. Method In a naturalistic national cohort of 449 patients who initiated LAI treatment in the STAR Network Depot Study, two groups were identified based on off- or on-label prescriptions. A multivariate logistic regression analysis was used to test several clinically relevant variables and identify those associated with the choice of FGA vs SGA prescription in the off-label group. Results SGA LAIs were more commonly prescribed in everyday practice, without significant differences in their on- and off-label use. Approximately 1 in 4 patients received an off-label prescription. In the off-label group, the most frequent diagnoses were bipolar disorder (67.5%) or any personality disorder (23.7%). FGA vs SGA LAI choice was significantly associated with BPRS thought disorder (OR = 1.22, CI95% 1.04 to 1.43, p = 0.015) and hostility/suspiciousness (OR = 0.83, CI95% 0.71 to 0.97, p = 0.017) dimensions. The likelihood of receiving an SGA LAI grew steadily with the increase of the BPRS thought disturbance score. Conversely, a preference towards prescribing an FGA was observed with higher scores at the BPRS hostility/suspiciousness subscale. Conclusion Our study is the first to identify predictors of FGA vs SGA choice in patients treated with off-label LAI antipsychotics. Demographic characteristics, i.e. age, sex, and substance/alcohol use co-morbidities did not appear to influence the choice towards FGAs or SGAs. Despite a lack of evidence, clinicians tend to favour FGA over SGA LAIs in bipolar or personality disorder patients with relevant hostility. Further research is needed to evaluate treatment adherence and clinical effectiveness of these prescriptive patterns
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