5,977 research outputs found
A FLAMINGOS Deep Near Infrared Imaging Survey of the Rosette Complex I: Identification and Distribution of the Embedded Population
We present the results of a deep near-infrared imaging survey of the Rosette
Complex. We studied the distribution of young embedded sources using a
variation of the Nearest Neighbor Method applied to a carefully selected sample
of near-infrared excess (NIRX) stars which trace the latest episode of star
formation in the complex. Our analysis confirmed the existence of seven
clusters previously detected in the molecular cloud, and identified four more
clusters across the complex. We determined that 60% of the young stars in the
complex and 86% of the stars within the molecular cloud are contained in
clusters, implying that the majority of stars in the Rosette formed in embedded
clusters. We compare the sizes, infrared excess fractions and average
extinction towards individual clusters to investigate their early evolution and
expansion. We found that the average infrared excess fraction of clusters
increases as a function of distance from NGC 2244, implying a temporal sequence
of star formation across the complex. This sequence appears to be primordial,
possibly resulting from the formation and evolution of the molecular cloud and
not from the interaction with the HII region.Comment: Accepted by Astrophysical Journa
Smart charging management for electric vehicle battery chargers
This paper proposes a smart battery charging
strategy for Electric Vehicles (EVs) targeting the future smart
homes. The proposed strategy consists in regulate the EV battery
charging current in function of the total home current, aiming to
prevent overcurrent trips in the main switch breaker.
Computational and experimental results were obtained under
real-time conditions to validate the proposed strategy. For such
purpose was adapted a bidirectional EV battery charger
prototype to operate in accordance with the aforementioned
strategy. The proposed strategy was validated through
experimental results obtained both in steady and transient states.
The results show the correct operation of the EV battery charger
even under heavy load variations.Fundação para a Ciência e Tecnologia within the Project Scope: PEst - OE/EEI/UI0319/201
Assessment of a battery charger for electric vehicles with reactive power control
Batteries of Electric Vehicles (EVs) and Plug-in
Hybrid Electric Vehicles (PHEVs) have a large potential not
only to provide energy for the locomotion of these vehicles, but
also to interact, in dynamic way, with the power grid. Thereby,
through the energy stored in the batteries, these vehicles can be
used to regulate the active and the reactive power, as local
Energy Storage Systems. This way, EVs can contribute to help
the power grid to regulate the active and reactive power flow in
order to stabilize the production and consumption of energy.
For this propose should be defined usage profiles, controlled by
a collaborative broker, taking into account the requirements of
the power grid and the conveniences of the vehicle user. Besides,
the interface between the power grid and the EVs, instead of
using typical power converters that only work on unidirectional
mode, need to use bidirectional power converters to charge the
batteries (G2V - Grid-to-Vehicle mode) and to deliver part of
the stored energy in the batteries back to the power grid (V2G -
Vehicle-to-Grid mode). With the bidirectional power converter
topology presented in this paper, the consumed current is
sinusoidal and it is possible to regulate the power factor to
control the reactive power, aiming to contribute to mitigate
power quality problems in the power grid. To assess the
behavior of the presented bidirectional power converter under
different scenarios, are presented some computer simulations
and experimental results obtained with a prototype that was
developed to be integrated in an Electric Vehicle.Fundação para a Ciência e a Tecnologia (FCT) - FCOMP-01-0124-FEDER-022674, PTDC/EEAEEL/
104569/2008, MIT-PT/EDAM-SMS/0030/2008.FEDER Funds, through the
Operational Programme for Competitiveness Factors (COMPETE
Comparison of charging systems for electric vehicles and their impact on electrical grid
This paper presents a comparison of four types of
on-board batteries charging systems for Electric Vehicles (EVs)
and Plug-in Hybrid Electric Vehicles (PHEVs), and their impact
on the power quality of the electrical power grid. In the
comparison are analyzed the features, the characteristics and the
operation of each charging system, aiming their controllability
and their impact on the electrical grid, mainly considering the
Total Harmonic Distortion (THD) of the consumed current and
the power factor. Besides the normal mode of operation to charge
the batteries, denominated Grid-to-Vehicle (G2V), in this paper
is also discussed the possibility of operation as Vehicle-to-Grid
(V2G), in which the batteries of the Electric Vehicle return part
of the stored energy back to the electrical grid. The operation of
the batteries charging systems for EVs is shown through
simulations and experimental results.FEDER Funds - Operational Programme for Competitiveness Factors (COMPETE)Fundação para a Ciência e a Tecnologia (FCT) - PTDC/EEA-EEL/104569/2008, MITPT/EDAM-SMS/0030/200
Influência de substratos na emergência de plântulas de biribá (Rollinia mucosa (Jacq.) Baill).
O conhecimento do potencial do biribá e dos fatores que propiciam a germinação de suas sementes podem ser considerados pontos de partida para que a espécie venha a ser explorada de maneira racional e sustentável. Diante desses aspectos, o trabalho teve como objetivo testar diferentes substratos para emergência e desenvolvimento de plântulas de biribá.bitstream/CPAF-RO-2009-09/12215/1/ct93_biriba.pd
Superação de dormência em sementes de biribá (Rollinia mucosa (Jacq.) Baill).
O estado de dormência em sementes se manifesta pelo retardamento da germinação por um período de maior ou menor amplitude, mesmo que as condições ambientais (luz, temperatura, água, oxigênio) sejam favoráveis à germinação. A quebra da dormência pode ser feita utilizando-se escarificação mecânica, térmica e química. Esses métodos baseiam-se na quebra do tegumento, que é impermeável à água, promovendo a embebição, etapa inicial do processo germinativo. As regras para análise de sementes recomendam vários tratamentos para a quebra de dormência. No entanto não há recomendações para as Annonaceae em geral.bitstream/CPAF-RO-2009-09/12214/1/ct94_sementesdebiriba.pd
Peripheral lymphocyte subpopulations in prostate cancer - data from an animal model
Introduction: Prostate cancer (PCa) is one of the most common cancers among men worldwide. The presence of immune cells in human cancer raises a fundamental question in oncology. The interaction between immune system and PCa is an important field for translational research. This work aimed to characterize the peripheral lymphocyte subpopulations in a PCa animal model.
Methods: Twenty-five male Wistar Unilever rats (Rattus norvegicus) with twelve weeks of age were randomly divided into two groups: Control (n=10) and Induced (n=15). All procedures were approved by the Portuguese Competent Authority (DGAV no. 021326). Prostate lesions were induced through the administration of flutamide (50 mg/kg, TCI Chemicals, USA), testosterone propionate (100 mg/kg, TCI Chemicals, USA) and N-methyl-N-nitrosourea (30 mg/kg, Sigma Chemical Co., Spain), and crystalline testosterone implants. Animals were humanely sacrificed at 61 weeks of age. Peripheral blood of all animals was collected by intracardiac puncture and transferred into tubes containing EDTA salt as an anticoagulant for flow cytometry analysis. The following conjugated monoclonal antibodies were used: cyCD3-BV421, CD3-FITC, CD25-APC, CD45-BV510, CD127-PE, CD161-FITC, CD4-PE/Cy7, CD45RA-APC/Cy7, OX-82-PE and CD8a-PerCP. The flow cytometry immunophenotyping was performed in a BD FACSCantoTM II cytometer (BD Biosciences, USA) and data were analysed with InfinicytTM, flow cytometry software 1.7 version. Statistical analysis was performed using SPSS 25. The differences were considered statistically significant at p<0.05.
Results: Although differences did not reach the level of statistical significance, the populations of CD3+ and CD4+ lymphocytes were higher in control group when compared with induced group (p>0.05). Similarly, CD8+ lymphocyte population was higher in control group than in induced group (9.56±0.74 vs 6.38±0.32) (p<0.05). Inversely, the population of regulatory T cells (TRegs) (2.99±0.46 vs 4.630±0.35), the TRegs/CD8 ratio (0.35±0.09 vs 0.45±0.08) and the TRegs/Natural Killer ratio (0.52±0.05 vs 1.03±0.13) were higher in induced group when compared with control one (p<0.05).
Conclusion: The population of Tregs increased in induced animals, while the population of NK decreased in these animals, which is in accordance with data previously published by other authors reporting the increase of Tregs and decrease of NK cells in animals with cancer. The characterization of these immune system subpopulation can be important for other studies such as preclinical cancer models
Understanding mobility in networks
Motivated by the growing number of mobile devices capable of connecting and exchanging messages, we propose a methodology aiming to model and analyze node mobility in networks. We note that many existing solutions in the literature rely on topological measurements calculated directly on the graph of node contacts, aiming to capture the notion of the node's importance in terms of connectivity and mobility patterns beneficial for prototyping, design, and deployment of mobile networks. However, each measure has its specificity and fails to generalize the node importance notions that ultimately change over time. Unlike previous approaches, our methodology is based on a node embedding method that models and unveils the nodes' importance in mobility and connectivity patterns while preserving their spatial and temporal characteristics. We focus on a case study based on a trace of group meetings. The results show that our methodology provides a rich representation for extracting different mobility and connectivity patterns, which can be helpful for various applications and services in mobile networks
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