2,346 research outputs found
Modélisation de l'évolution du couvert nival, sur le sous-bassin LG4 de la rivière La Grande dans le nord du Québec, à l'aide du modèle français CROCUS
Au Québec, l'accumulation de la neige au sol prend une grande importance dans bon nombre d'activités humaines comme la production d'hydroélectricité. Face à cette importance de la neige, il devient fort intéressant de faire appel à des outils de modélisation dans le but de faire le suivi complet du manteau neigeux par la simulation des différents processus physiques agissant sur le couvert nival. En ce sens, la présente recherche vise à évaluer la capacité d'adaptation aux conditions environnementales du Québec, du modèle français multicouches CROCUS de suivi et de fonte du couvert nival, en vue de son utilisation ultérieure. Le choix du site d'étude s'accorde avec la présence de stations d'acquisition de données sur le couvert nival et la disponibilité d'un large éventail de données météorologiques essentielles aux modélisations.Suite au prétraitement des données d'entrée, le modèle CROCUS a pu être étalonné dans le but d'évaluer ses aptitudes à simuler l'évolution de l'épaisseur et de l'équivalent en eau du couvert nival, de même que les profils de densité et de température de ce couvert. Compte tenu des données disponibles, les résultats des périodes d'étalonnage et de vérification peuvent être considérés comme très bons et très encourageants pour des applications ultérieures de CROCUS au Québec.In Québec, snow accumulation on the ground is important for a large number of activities, including hydroelectric production. Snow being an important environmental aspect to look at for operations in cold regions, making use of adequate models able to simulate the various physical processes affecting the characteristics of the snowpack throughout the entire snow season becomes also quite important. So, the present project aims to evaluate the ability of the CROCUS French multilayer snow model to be adapted to Northern Quebec environmental conditions. The choice of the study area has been done on the basis of data availability on both the temporal evolution the snowpack at three automatic stations and the meteorological variables necessary as input to the model. Following preprocessing of input data, the CROCUS model has been calibrated in order to evaluate his capability to simulate the temporal evolution not only of the thickness and water equivalent of the snowpack, but also of the density and temperature profiles within the pack. Given the available data, the results for both the calibration and verification periods can be considered as good and very encouraging for future applications of the CROCUS model in Québec
Conceptual models for describing virtual worlds
A conceptual model of a virtual world is a high-level representation of how the objects behave and how they are
related to each other. The conceptual models identify the most essential elements of the reality to be simulated. This
is the first and a very important step in the process of designing a virtual world. Afterwards, specific and complex
models can be implemented and inserted into these conceptual models. This paper provides an overview of existing
conceptual models used to design virtual worlds. A number of existing frameworks and architecture for describing
virtual worlds are classified into six kinds of conceptual models: unstructured, graphic-oriented, network-oriented,
object-oriented, environment-oriented and relational graph-oriented representations. The advantages and issues
regarding virtual world design, management, reusability and interoperability are discussed
Sulphur-bearing molecules in diffuse molecular clouds: new results from SOFIA/GREAT and the IRAM 30 m telescope
We have observed five sulphur-bearing molecules in foreground diffuse
molecular clouds lying along the sight-lines to five bright continuum sources.
We have used the GREAT instrument on SOFIA to observe the 1383 GHz transitions of SH towards the star-forming regions W31C,
G29.96-0.02, G34.3+0.1, W49N and W51, detecting foreground absorption towards
all five sources; and the EMIR receivers on the IRAM 30m telescope at Pico
Veleta to detect the HS 1(10)-1(01), CS J=2-1 and SO 3(2)-2(1) transitions.
In nine foreground absorption components detected towards these sources, the
inferred column densities of the four detected molecules showed relatively
constant ratios, with N(SH)/N(HS) in the range 1.1 - 3.0, N(CS)/N(HS)
in the range 0.32 - 0.61, and N(SO)/N(HS) in the range 0.08 - 0.30. The
observed SH/H ratios - in the range (0.5-2.6) - indicate
that SH (and other sulphur-bearing molecules) account for << 1% of the
gas-phase sulphur nuclei. The observed abundances of sulphur-bearing molecules,
however, greatly exceed those predicted by standard models of cold diffuse
molecular clouds, providing further evidence for the enhancement of endothermic
reaction rates by elevated temperatures or ion-neutral drift. We have
considered the observed abundance ratios in the context of shock and turbulent
dissipation region (TDR) models. Using the TDR model, we find that the
turbulent energy available at large scale in the diffuse ISM is sufficient to
explain the observed column densities of SH and CS. Standard shock and TDR
models, however, fail to reproduce the column densities of HS and SO by a
factor of about 10; more elaborate shock models - in which account is taken of
the velocity drift, relative to H, of SH molecules produced by the
dissociative recombination of HS - reduce this discrepancy to a factor
~ 3.Comment: 30 pages, accepted for publication in A&
RF and THz Identification Using a New Generation of Chipless RFID Tags
This article presents two chipless RFID approaches where data are reading using electromagnetic waves and where the medium encoding the data is completely passive. The former approach rests on the use of RF waves (more precisely the ultra-wide band UWB). The tags developed for this application are comparable with very specific, planar, conductive, radar targets where the relation between the tag geometry and its electromagnetic signature is perfectly known and is used to encode the data. The principle of operation as well as the realization process of the RF tags presented in this paper is similar to those already reported in the literature. However, contrary to the majority of chipless RFID tags, these labels do not present an antenna function dissociated from the circuit part where the data are stored. Here, functions such as the receiver, the treatment and the emitter of the signal are closely dependent. The data storage capacity of the RF chipless tags is proportional to of the used frequency bandwidth. As radio spectrum is regulated, the number of possible encoding bits is thus strongly limited with this technology. This is the reason why we introduce a new family of tags radically different from the preceding one, where data is encoded in volume thanks to a multilayer structure operating in the THz domain. These two approaches although different are complementary and allow to increase significantly the data storage capacity of the chipless tags. Simulation and experimental results are reported in this paper for both configurations. We demonstrate a coding capacity of 3.3 bit/cm2 for RFID chipless tags and a potential 10 bits coding capacity in the THz domain
Cytological features of uterine tumors resembling ovarian sex-cord tumors in liquid-based cervical cytology: a potential pitfall. Report of a unique and rare case.
Uterine tumors resembling ovarian sex-cord tumors (UTROSCTs) are rare uterine neoplasms of uncertain etiology that resemble the sex cord tumors of the ovary and display a combined sex cord, epithelial, and smooth muscle immunophenotype. Most tumors are associated with a benign clinical course. We report the first cytological description of uterine UTROSCTs in liquid-based cervical cytology (LBC). A menopausal woman was discovered to have a uterine intraluminal polypoid mass protruding through the vagina. A Pap test was performed, and the LBC preparation showed isolated tumor cells with scant cytoplasm and slightly irregular, ovoid nuclei with fine chromatin and small nucleoli. Final histological evaluation identified a UTROSCT. This diagnostic possibility, albeit rare, should be included in the differential diagnosis when isolated malignant-appearing adenocarcinomatous cells are seen in women in the above scenario. As these features are not specific, they may result in misinterpretation with tumors that are more common and aggressive
Management of radiation dermatitis in patients receiving cetuximab and radiotherapy for locally advanced squamous cell carcinoma of the head and neck: proposals for a revised grading system and consensus management guidelines
Background: Radiation dermatitis developing in patients receiving cetuximab concomitantly with radiotherapy for locally advanced squamous cell carcinoma of the head and neck (LA SCCHN) is now recognized to have different pathophysiological and clinical characteristics to the radiation dermatitis associated with radiotherapy or concomitant chemotherapy and radiotherapy. Current grading tools were not designed to grade this type of radiation dermatitis; their use may lead to misclassification of reactions and inappropriate management strategies, potentially compromising cancer treatment. Patients and methods: An advisory board of seven leading European specialists (three medical oncologists, three radiation oncologists and a dermatologist) with extensive experience of the use of cetuximab plus radiotherapy produced consensus guidelines for the grading and management of radiation dermatitis in patients receiving cetuximab plus radiotherapy. Results: Modifications to the current, commonly used National Cancer Institute—Common Terminology Criteria for Adverse Events version 4.3 for grading radiation dermatitis were proposed. Updated management guidelines, building on previously published guidelines from 2008, were also proposed. Conclusions: The proposed revisions to the grading system and updated management guidelines described here represent important developments toward the more appropriate grading and effective management of radiation dermatitis in patients receiving cetuximab plus radiotherapy for LA SCCH
Kinetically Inhibited Order in a Diamond-Lattice Antiferromagnet
Frustrated magnetic systems exhibit highly degenerate ground states and
strong fluctuations, often leading to new physics. An intriguing example of
current interest is the antiferromagnet on a diamond lattice, realized
physically in A-site spinel materials. This is a prototypical system in three
dimensions where frustration arises from competing interactions rather than
purely geometric constraints, and theory suggests the possibility of unusual
magnetic order at low temperature. Here we present a comprehensive
single-crystal neutron scattering study of CoAl2O4, a highly frustrated A-site
spinel. We observe strong diffuse scattering that peaks at wavevectors
associated with Neel ordering. Below the temperature T*=6.5 K, there is a
dramatic change in the elastic scattering lineshape accompanied by the
emergence of well-defined spin-wave excitations. T* had previously been
associated with the onset of glassy behavior. Our new results suggest instead
that T* signifies a first-order phase transition, but with true long-range
order inhibited by the kinetic freezing of domain walls. This scenario might be
expected to occur widely in frustrated systems containing first-order phase
transitions and is a natural explanation for existing reports of anomalous
glassy behavior in other materials.Comment: 40 pages, 9 figures, Introduction and discussion altered and
expanded. Additional section and figure added to Supplementary Informatio
Science results from the imaging Fourier transform spectrometer SpIOMM
SpIOMM is an imaging Fourier transform spectrometer designed to obtain the
visible range (350 to 850 nm) spectrum of every light source in a circular
field of view of 12 arcminutes in diameter. It is attached to the 1.6-m
telescope of the Observatoire du Mont Megantic in southern Quebec. We present
here some results of three successful observing runs in 2007, which highlight
SpIOMMs capabilities to map emission line objects over a very wide field of
view and a broad spectral range. In particular, we discuss data cubes from the
planetary nebula M27, the supernova remnants NGC 6992 and M1, the barred spiral
galaxy NGC7479, as well as Stephans quintet, an interacting group of galaxies.Comment: 10 pages, 7 figures, to appear in "Ground-based and Airborne
Instrumentation for Astronomy II", SPIE conference, Marseille, 23-28 June
200
Gender and Institutional Aspects of Climate-Smart Agricultural Practices: Evidence from Kenya
This paper analyses gender differences in awareness and adoption of climate-smart agricultural (CSA) practices. It examines what factors are associated with the likelihood of adoption of a wide range of CSA practices for 376 women and 375 men in two different areas of Kenya. This information is aimed at improving the targeting and design of interventions that are trying to achieve greater and more equitable agricultural development in East Africa and elsewhere. Our results suggest there is still much work to be done in increasing awareness of improved agricultural practices that enhance livelihoods and resilience to change, including a changing climate. Simply put, increasing awareness is necessary to increase adoption
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