2,512 research outputs found
Molecular gas and a new young stellar cluster in the far outer Galaxy
We investigate the star-formation ocurring in the region towards
IRAS07527-3446 in the molecular cloud [MAB97]250.63-3.63, in the far outer
Galaxy. We report the discovery of a new young stellar cluster, and describe
its properties and those of its parent molecular cloud. Near-infrared JHKS
images were obtained with VLT/ISAAC, and millimetre line CO spectra were
obtained with the SEST telescope. VLA archive date were also used. The cloud
and cluster are located at a distance of 10.3 kpc and a Galactocentric distance
of 15.4 kpc, in the far outer Galaxy. Morphologically, IRAS 07527-3446 appears
as a young embedded cluster of a few hundred stars seen towards the position of
the IRAS source, extending for about 2-4 pc and exhibiting sub-clustering. The
cluster contains low and intermediate-mass young reddened stars, a large
fraction having cleared the inner regions of their circumstellar discs
responsible for (H-Ks) colour excess. The observations are compatible with a <
5 Myr cluster with variable spatial extinction of between Av = 5 and Av = 11.
Decomposition of CO emission in clumps, reveals a clump clearly associated with
the cluster position, of mass 3.3 x 10^3 M(solar). Estimates of the slopes of
the Ks-band luminosity function and of the star-formation efficiency yield
values similar to those seen in nearby star-formation sites. These findings
reinforce previous results that the distant outer Galaxy continues to be active
in the production of new and rich stellar clusters, with the physical
conditions required for the formation of rich clusters continuing to be met in
the very distant environment of the outer Galactic disc.Comment: 11 pages, 13 figure
Shacc: a functional prototyper for a component calculus
For individual study onlyOver the last decade component-based software development arose as a promising paradigm to deal with the ever increasing complexity in software design, evolution and reuse. Shacc is a prototyping tool for component-based systems in which components are modelled coinductively as generalized Mealy machines. The prototype is built as a Haskell library endowed with a graphical user interface developed in Swing.Fundação para a Ciência e a Tecnologia (FCT
Modelling of rammed earth under shear loading
The intensive use of earth as a building material since ancient times resulted in an important and significant earthen built heritage currently existing worldwide spread. The rammed earth technique has a significant presence in this heritage, where it served to build from simple dwell-ings to fortresses. However, the high vulnerability of rammed earth constructions to decay agents and to seismic events puts in risk their further existence and the lives of millions of peo-ple. With respect to the seismic behaviour of rammed earth walls, the understanding and mod-elling of their shear behaviour are topics underdeveloped in the bibliography. Nevertheless, these topics are of extreme importance in the preservation and strengthening of rammed earth constructions. Therefore, this paper presents a numerical work aiming at modelling the non-linear behaviour of unstabilised rammed earth under shear loading, resorting to the finite ele-ments method (FEM). The models were used to simulate the behaviour of a set of rammed earth wallets tested under diagonal compression. Both macro- and micro-modelling approach-es were considered, where the objective of this last approach was to evaluate the influence of apparent weakness of the interfaces between layers on the shear behaviour. The total strain ro-tating crack model (TSCRM) was used to simulate the behaviour of the rammed earth material, while the Mohr-Coulomb failure criterion was used to simulate the behaviour of interfaces be-tween layers. Furthermore, uncertainties related to the definition of the input parameters re-quired performing a sensitivity analysis. The numerical models achieved good agreement with the experimental results and the compressive strength, the Poisson’s ratio, the tensile strength and the tensile fracture energy revealed to be the most important parameters in the analyses.Fundação para a Ciência e a Tecnologia (FC
Photon-number-resolving segmented avalanche-photodiode detectors
We investigate the feasibility and performance of photon-number-resolved
photodetection employing avalanche photodiodes (APDs) with low dark counts. The
main idea is to split n photons over m modes such that every mode has no more
than one photon, which is detected alongside propagation by an APD. We
characterize performance by evaluating the purities of positive-operator-valued
measurements (POVMs), in terms of APD number and photon loss.Comment: 5 pages, 7 figures, submitted for publicatio
Modelling the structural behaviour of rammed earth components
Proceedings of the Twelfth International Conference on Computational Structures Technology, B.H.V. Topping and P. Iványi, (Editors), Civil-Comp Press, Stirlingshire, Scotland.The rammed earth technique has a significant presence in the earthen built heritage, where was used to build from simple dwellings to fortresses. However, the high vulnerability of rammed earth construction to decay agents and to seismic events puts at risk their further existence and the lives of millions of people. With respect to the seismic behaviour of rammed earth walls, the understanding and modelling of their shear behaviour are topics rarely approached in literature. Nevertheless, these topics are of significant importance in the preservation and strengthening of rammed earth constructions. This paper presents experimental and numerical work where the shear behaviour of unstabilised rammed earth is analysed. The experimental program consisted in the testing of several unstabilised rammed earth wallets subject to diagonal compression, which allowed a better understanding of the shear behaviour of unstabilised rammed earth. The numerical work consists of the modelling, of the previous tests, using the finite element method and by considering both the macroand micro-modelling approaches. In general, the numerical models showed a good agreement with the experimental results.The authors would like to thank gratefully the funding provided by the Portuguese Science and Technology Foundation through project FCOMP-01-0124-FEDER-028864 (FCT-PTDC/ECM-EST/2396/2012). Furthermore, the authors wish to express their gratitude to Júlio Machado for his valuable help in the experimental
program.info:eu-repo/semantics/publishedVersio
Residual granitic soil improvement for rammed earth construction
This paper describes the research developed to evaluate the performance of stabilised residual granitic soil from the north region of Portugal. It is part of a research project designed to investigate the possibility of using this soil for rammed earth construction. Since its reduced plasticity makes the use of lime less effective, and the increasing environmental concerns with cement production can no longer be ignored, the study was focused on binders made from alkaline activation of low calcium fly ash. Therefore, the aim of this work was to determine, through a parametric analysis using laboratory tests, the optimum fly ash – based alkaline activated binder for improving granitic soil, in terms of mechanical strength. Identification of the key parameters allowed the characterisation of the most effective mixtures, which will be later used in the construction of large rammed earth wall panels that will be tested according to proper specifications
The challenge of long-distance over-the-air wireless links in the ocean: a survey on water-to-water and water-to-land miot communication
Robust wireless communication networks are a cornerstone of the modern world, allowing data to be transferred quickly and reliably. Establishing such a network at sea, a Maritime Internet of Things (MIoT), would enhance services related to safety and security at sea, environmental protection, and research. However, given the remote and harsh nature of the sea, installing robust wireless communication networks with adequate data rates and low cost is a difficult endeavor. This paper reviews recent MIoT systems developed and deployed by researchers and engineers over the past few years. It contains an analysis of short-range and long-range over-the-air radio-frequency wireless communication protocols and the synergy between these two in the pursuit of an MIoT. The goal of this paper is to serve as a go-to guide for engineers and researchers that need to implement a wireless sensor network at sea. The selection criterion for the papers included in this review was that the implemented wireless communication networks were tested in a real-world scenario.cofunded by the project K2D: Knowledge and Data from the Deep to Space with reference POCI-01-0247-FEDER-045941, cofinanced by the European Regional Development Fund (ERDF), through the Operational Program for Competitiveness and Internationalization (COMPETE2020), and by the Portuguese Foundation for Science and Technology (FCT) under the MIT Portugal Program. This work is also cofinanced by national funds through FCT–Fundação para a Ciência e Tecnologia, I.P., under project SONDA (PTDC/EME-SIS/1960/2020). T.M. thanks FCT for grant SFRH/BD/145070/201
Citalopram administration does not promote function or histological recovery after spinal cord injury
Citalopram is a selective serotonin reuptake inhibitor, and although widely used as an antidepressant, this drug has also demonstrated interesting repairing properties leading to motor recovery and pathology amelioration in animal models of stroke and degeneration. Here, we tested the efficacy of both 7-day and 8-week citalopram treatment in a contusive spinal cord injury (SCI) rat model. A combination of behavioral tests, histological and serum cytokine analysis was used to assess overall recovery. Despite promoting a mild reduction of inflammatory cells as well as an early, but transient increase of specific serum cytokines, citalopram administration showed no overall beneficial effects on motor performance or lesion extension. Our results do not support citalopram treatment as a therapeutic strategy for SCI.This research was funded by Prémios Santa Casa Neurociências—Prize Melo e Castro for SpinalCord Injury Research, Grant Number MC-04/17 and the Portuguese Foundation for Science and Technology(FCT) through the Scientific Employment Stimulus to N. Silva and S. Monteiro (CEECIND/04794/2017 and CEECIND/01902/2017) and fellowships to RL (PD/BDE/127836/2016); EDG (SFRH/BD/103075/2014);NLV (SFRH/BD/136952/2018) and R.AS (PDE/BDE/113596/2015).This work was also funded by FEDER,through the Competitiveness Internalization Operational Program (POCI) and by National funds, throughthe Foundation for Sciences and Technology (FCT), under the scope of the projects POCI-01-0145-FEDER-007038,POCI-01-0145-FEDER-029206, POCI-01-0145-FEDER-029751 and PTDC/BTM-MAT/29968/2017. This work hasbeen funded by ICVS Scientific Microscopy Platform, member of the national infrastructure PPBI - PortuguesePlatform of Bioimaging (PPBI-POCI-01-0145-FEDER-022122; by National funds, through the Foundationfor Science and Technology (FCT) - project UIDB/50026/2020 and UIDP/50026/2020; and by the projectsNORTE-01-0145-FEDER-000013, supported by the Northern Portugal Regional Operational Program (NORTE2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF)
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