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Search Results: 1 - 10 of 5678 matches for " Vera Djepa "
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Improved Retrieval of Sea Ice Thickness and Density from Laser Altimeter  [PDF]
Vera Djepa
Atmospheric and Climate Sciences (ACS) , 2014, DOI: 10.4236/acs.2014.45080
Abstract: The sensitivity of weather and climate system to sea ice thickness (SIT) in the Arctic is recognised from various studies. Decrease of SIT will affect atmospheric circulation, temperature, precipitation and wind speed in the Arctic and remotely. Ice thermodynamics and dynamic properties depend strongly on ice and snow thickness. The heat transfer through ice critically depends on ice thickness. Long term accurate SIT records with corresponding uncertainties are required for improved seasonal weather forecast and estimate of the sea ice mass balance. Satellite radar and Laser Altimeter (LA) provide long term records of sea ice freeboard. Assuming isostatic equilibrium, SIT is retrieved from the freeboard, extracted from radar altimeter (RA) or LA, where the snow depth, density, ice and water density are input variables in the equation for hydrostatic equilibrium to derive SIT from LA or RA. Different input variables (snow depth, density, ice and water density) with unknown accuracy have been applied from various authors to retrieve SIT and Sea Ice Draft (SID) from RA or LA, leading to not comparative results. Sea ice density dependence on ice type, thermodynamic properties and freeboard is confirmed with different studies. Sensitivity analyses confirm the great impact of sea ice density, snow depth and density on accuracy of the retrieved SIT and the importance of inserting variable ice density (VID) in the equation for hydrostatic equilibrium for more accurate SIT retrieval, weather and climate forecast. The impact of sea ice density and snow depth and density on retrieved SIT from the freeboard derived from LA and RA have been analyzed in this study using the equation for hydrostatic equilibrium, statistical and sensitivity analyses. An algorithm is developed to convert the freeboard, derived from LA in SIT, inserting VID in the equation for hydrostatic equilibrium. The algorithm is validated with field, laboratory studies and collocated SIT retrieved from RA on board Envisat. The accuracy of the developed algorithm is analyzed, using statistical and uncertainty analyses. It is found that the uncertainty of the retrieved SIT from LA is decreased 7.6 times (from rhi = 59 cm for fixed ice density) if variable ice density is inserted in the equation for hydrostatic equilibrium. The SIT, which has been retrieved from the freeboard derived from LA is validated with collocated SIT derived from RA2 on Envisat, using variable ice density. The bias of the mean SIT derived from LA and RA has been reduced from -1.1 m to about one millimeter when VID is
Sensitivity, uncertainty analyses and algorithm selection for Sea Ice Thickness retrieval from Radar Altimeter
Vera Djepa
Physics , 2013,
Abstract: For accurate forecast of climate change, sea ice mass balance, ocean circulation and sea- atmosphere interactions is required to have long term records of Sea Ice Thickness (SIT). Different approaches have been applied to retrieve SIT and only satellite altimetry, radar or laser, have been proven to provide hemispheric estimates of SIT distribution over a sufficient thickness range. To simplify the algorithm for SIT retrieval from RA, constant ice density has been applied until now, which lead to different results for derived SIT and SID, in dependence on input information for sea ice density and snow depth. The purpose of this paper is to select algorithm for SID and SIT retrieval from RA, using statistical, sensitivity analyses and independent observations of SID from moored ULS, or on Submarine. The impact of ice density and snow depth on accuracy of the retrieved SIT has been examined, applying sensitivity analyses, and the propagated uncertainties have been summarised. Accuracy of algorithms for snow depth retrieval in the Arctic have been discussed and it is concluded that the assumption of half snow depth over First Year Ice (FYI) will lead always to underestimation of SIT and SID derived from RA and is not applicable for SIT retrieval from RA, using the equation for hydrostatic equilibrium. Algorithms for freeboard depended ice densities and SIT retrieval from RA have been developed and a FD algorithm for SIT retrieval from RA has been selected, based on statistical, sensitivity analyses and comparison with collocated observations of SID from moored ULS and on Submarine . ESA (ERS1, 2, ENVISAT, CryoSat2), future ESA (Sentinel) and NASA satellite and airborne missions, climate and numerical forecast programs will benefit the results of this paper.
Second Language Acquisition: Reconciling Theories  [PDF]
Vera Menezes
Open Journal of Applied Sciences (OJAppS) , 2013, DOI: 10.4236/ojapps.2013.37050
Abstract:

This article argues that previous attempts to explain SLA should not be disregarded. Instead, when they are put together, they provide a broader and deeper view of the acquisition process. There is evidence to support the claim that second language acquisition (SLA) is a complex adaptive system due to its inherent ability to adapt to different conditions present in both internal and external environments. Based on this understanding, widely discussed second language theories, including behaviorism, will be treated as explanations of parts of a whole, since each captures a different aspect of SLA. In order to justify this assumption, excerpts from some English language learning histories are provided to exemplify how learners describe their learning processes. The final claim is that SLA should be seen as a chaotic/complex system.

Music, Eurocentrism and Identity: The Myth of the Discovery of America in Chilean Music History  [PDF]
Alejandro Vera
Advances in Historical Studies (AHS) , 2014, DOI: 10.4236/ahs.2014.35024
Abstract: During the past century, Edmundo O’Gorman, Tzvetan Todorov, Enrique Dussel and other scholars pointed out the Eurocentric perspective implied in traditional narratives about the discovery of America, most of which intended to confirm Europe as the center of world history and culture. At the same time, Claude Lévi-Strauss, Hayden White and others argued for the mythical character of history. According to them, even though historians attempted to assemble documentary evidence objectively, they constructed their narratives incorporating such evidence in preexisting stories, characters and categories with a mythical origin. This paper uses these viewpoints to analyze and criticize the way in which Chilean music history has been constructed, particularly during the republican era. The main hypothesis is that traditional discourses about that history have constantly recycled narratives on the discovery of America, which thus operates as a kind of founding myth for historical and musicological interpretations, especially when dealing with turning points such as the change of dynasty (1700), the beginning of independence (c. 1810) and the centenary of the republic (1910). A corollary would be that documentary evidence about music has been frequently hidden or distorted precisely in order to fit such a myth. That is why the present paper examines both bibliography and original documents found in different archives.
The Effect of a Mother’s Level of Attachment and Her Emotional Intelligence on a Child’s Health during Its First Year of Life  [PDF]
Elena Nikolaeva, Vera Merenkova
Psychology (PSYCH) , 2013, DOI: 10.4236/psych.2013.45068
Abstract:

The aim of this study was to investigate the possibility of predicting the health of a child during its first year by using the mother’s emotional intelligence and the level of her attachment to the child. Serving as test subjects were 50 mother-child pairs during the first year of life and 50 mother-child pairs during the second year of life (altogether 200 individuals). It was shown that the likelihood of dismissing a diagnosis given to a child at a maternity clinic depends on the level of the mother’s acceptance of the child and not on her emotional intelligence and anxiety.

Sem mágicas solu??es: a preven??o e o cuidado em HIV/ AIDS e o processo de emancipa??o psicossocial
Paiva, Vera;
Interface - Comunica??o, Saúde, Educa??o , 2002, DOI: 10.1590/S1414-32832002000200003
Abstract: this text discusses the need to politicize psycho-educational arenas and presents the idea of a "psycho-social emancipation" as one of the references for improved operationalization of the notion of vulnerability in the field of prevention of new hiv infections and of the organization of care for those who are aids carriers. reflecting on actions designed to encourage patients to take their medication and use condoms, it suggests that the prevention of hiv should overcome models devised for "hiv negative" people and that the prevent-assist continuum should be radicalized. to this end, it is pressing to: take into account the facts accumulated in the field of cultural analyses and of psychosocial research in the planning and organization of preventive actions and of providing assistance to hiv carriers, including, for instance, the ideas of oppressive social construction of two genders, masculine and feminine; overcome the notion of "individuals as consumers" (of services, educational programs, condoms and prescribed medication, of behaviors and safe practices to be practiced); foster the innovation of prevention and care actions. working with the idea of a "subject-citizen individual", co-participant in the psycho-educational arenas whose horizon consists of psychosocial emancipation, can enhance the quality of preventive actions and of integrated care of hiv and aids patients, so as to include "all" brazilians, according to the socio-cultural context of "each one", both men and women, testing positive or negative.
UNA NUEVA ESPECIE DE CHILENOPERLA (PLECOPTERA: GPJPOPTERYGIDAE) Y LAS CONSECUENCIAS TAXONóMICAS DEL DESCUBRIMIENTO DE SU NINFA
Vera,Alejandro;
Gayana (Concepción) , 2008, DOI: 10.4067/S0717-65382008000200005
Abstract: anew species of gripopterygidae (chilenoperla elongata sp. nov.) is described based on adults of both sexes and nymphs from chile. the nymph was associated by means of growing in controlled conditions. the nymph of the new species is similar to that oí pelurgoperla (sensu lilies, 1963). therefore, previous identifications and geographic distributions of these genera could be wrong. comments on the nymph of ch. puerilis are advanced at the light of this new finding.
Una nueva especie de Gripopterygidae de Chile, Potamoperla testacea n. sp. (Insecta: Plecoptera)
Vera,Alejandro;
Gayana (Concepción) , 2006, DOI: 10.4067/S0717-65382006000200003
Abstract: a new species of gripopterygidae: gripopteryginae (sensu mclellan described 1977) from chile potamoperla testacea n. sp. distributed between the seventh and tenth first regions. is both sexes and the nymph are given to know, this last one is associated by means of laboratory emergence. its generic location is discussed.
Estudio taxonómico del género Paraxeropsis Camousseight, 2008 (Insecta, Phasmatodea), con la descripción de P. camousseighti n. sp.
Vera,Alejandro;
Gayana (Concepción) , 2011, DOI: 10.4067/S0717-65382011000100005
Abstract: the imagos of both sexes and the egg of paraxeropsis camousseighti sp. n. are described, as well as biological observations of specimens collected in chile in one locality near the coast in the región del maule. its discovery complements the original diagnostic description of the genus and allows discussion of genital morphology and comparison with other recently studied species of phasmids.
In silico analysis of the endogenous time-keeping mechanism in citrus
Quecini, Vera;
Genetics and Molecular Biology , 2007, DOI: 10.1590/S1415-47572007000500008
Abstract: the endogenous time-keeping mechanism is responsible for organizing plant physiology and metabolism according to periodic environmental changes, such as diurnal cycles of light and dark and seasonal progression throughout the year. in plants, circadian rhythms control gene expression, stomatal opening, and the timing component of the photoperiodic responses, leading to enhanced fitness due to increased photosynthetic rates and biomass production. we have investigated the citrus genome databases of expressed sequence tags (est) in order to identify genes coding for functionally characterized proteins involved in the endogenous time-keeping mechanism in arabidopsis thaliana. approximately 180,000 est sequences from 53 libraries were investigated and 81 orthologs of clock components were identified. we found that the vast majority of arabidopsis circadian clock genes are present in citrus species, although some important components are absent such as srr1 and prr5. based on the identified transcripts, a model for the endogenous oscillatory mechanism of citrus is proposed. these results demonstrate the power of comparative genomics between model systems and economically important crop species to elucidate several aspects of plant physiology and metabolism.
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