698 resultados para Extreme environments
Resumo:
High levels of HIV-1 replication during the chronic phase of infection usually correlate with rapid progression to severe immunodeficiency. However, a minority of highly viremic individuals remains asymptomatic and maintains high CD4+ T cell counts. This tolerant profile is poorly understood and reminiscent of the widely studied nonprogressive disease model of SIV infection in natural hosts. Here, we identify transcriptome differences between rapid progressors (RPs) and viremic nonprogressors (VNPs) and highlight several genes relevant for the understanding of HIV-1-induced immunosuppression. RPs were characterized by a specific transcriptome profile of CD4+ and CD8+ T cells similar to that observed in pathogenic SIV-infected rhesus macaques. In contrast, VNPs exhibited lower expression of interferon-stimulated genes and shared a common gene regulation profile with nonpathogenic SIV-infected sooty mangabeys. A short list of genes associated with VNP, including CASP1, CD38, LAG3, TNFSF13B, SOCS1, and EEF1D, showed significant correlation with time to disease progression when evaluated in an independent set of CD4+ T cell expression data. This work characterizes 2 minimally studied clinical patterns of progression to AIDS, whose analysis may inform our understanding of HIV pathogenesis.
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Background: Pre-existing psychological factors can strongly influence coping with type 1 diabetes mellitus and interfere with self-monitoring. Psychiatric disorders seem to be positively associated with poor metabolic control. We present a case of extreme compulsive blood testing due to obsessive fear of hypoglycemia in an adolescent with type 1 diabetes mellitus. Case report: Type 1 diabetes mellitus (anti GAD-antibodies 2624 U/l, norm < 9.5) was diagnosed in a boy aged 14.3 years [170 cm (+ 0.93 SDS), weight 50.5 kg (+ 0.05 SDS)]. Laboratory work-up showed no evidence for other autoimmune disease. Family and past medical history were unremarkable. Growth and developmental milestones were normal. Insulin-analog based basal-bolus regime was initiated, associated to standard diabetic education. Routine psychological evaluation performed at the onset of diabetes revealed intermittent anxiety and obsessivecompulsive traits. Accordingly, a close psychiatric follow-up was initiated for the patient and his family. An adequate metabolic control (HbA1c drop from >14 to 8%) was achieved within 3 months, attributed to residual -cell function. In the following 6 months, HbA1c rose unexpectedly despite seemingly adequate adaptations of insulin doses. Obsessive fear of hypoglycemia leading to a severe compulsive behavior developed progressively with as many as 68 glycemia measurements per day (mean over 1 week). The patient reported that he could not bear leaving home with glycemia < 15 mmol/l, ending up with school eviction and severe intra-familial conflict. Despite intensive psychiatric outpatient support, HbA1c rose rapidly to >14% with glycemia-testing reaching peaks of 120 tests/day. The situation could only be discontinued through psychiatric hospitalization with intensive behavioral training. As a result, adequate metabolic balance was restored (HbA1c value: 7.1 %) with acceptable 10-15 daily glycemia measurements. Discussion: The association of overt psychiatric disorders to type 1 diabetes mellitus is very rare in the pediatric age group. It can lead to a pathological behavior with uncontrolled diabetes. Such exceptional situations require long-term admissions with specialized psychiatric care. Slow acceptation of a "less is better" principle in glycemia testing and amelioration of metabolic control are difficult to achieve.
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This paper reviews the concept of presence in immersive virtual environments, the sense of being there signalled by people acting and responding realistically to virtual situations and events. We argue that presence is a unique phenomenon that must be distinguished from the degree of engagement, involvement in the portrayed environment. We argue that there are three necessary conditions for presence: the (a) consistent low latency sensorimotor loop between sensory data and proprioception; (b) statistical plausibility: images must be statistically plausible in relation to the probability distribution of images over natural scenes. A constraint on this plausibility is the level of immersion;(c) behaviour-response correlations: Presence may be enhanced and maintained over time by appropriate correlations between the state and behaviour of participants and responses within the environment, correlations that show appropriate responses to the activity of the participants. We conclude with a discussion of methods for assessing whether presence occurs, and in particular recommend the approach of comparison with ground truth and give some examples of this.
Resumo:
This paper presents the use of our multimodal mixed reality telecommunication system to support remote acting rehearsal. The rehearsals involved two actors, located in London and Barcelona, and a director in another location in London. This triadic audiovisual telecommunication was performed in a spatial and multimodal collaborative mixed reality environment based on the 'destination-visitor' paradigm, which we define and put into use. We detail our heterogeneous system architecture, which spans the three distributed and technologically asymmetric sites, and features a range of capture, display, and transmission technologies. The actors' and director's experience of rehearsing a scene via the system are then discussed, exploring successes and failures of this heterogeneous form of telecollaboration. Overall, the common spatial frame of reference presented by the system to all parties was highly conducive to theatrical acting and directing, allowing blocking, gross gesture, and unambiguous instruction to be issued. The relative inexpressivity of the actors' embodiments was identified as the central limitation of the telecommunication, meaning that moments relying on performing and reacting to consequential facial expression and subtle gesture were less successful.
Resumo:
Aquest article pretén descriure el procés metodològic d'identificació i mesurament de les competències TIC dels professors i com a formadors en les TIC en un entorn d'aprenentatge en línia en l'Educació Superior portat a terme en el marc del Projecte Europeu Elene-TLC.La revisió de la recerca en les competències en línia del professor demostra que, en primer lloc, el mètode més utilitzat per a identificar aquestes competències és el focus group. En segon lloc, la tècnica Delphi és la tècnica més utilitzada per reunir el consens d'experts sobre quines són les competències principals per al professor en línia entre els que s'indiquen.La proposta metodològica descrita en aquest document consisteix en la creació de 7 grups de discussió en línia, l'objectiu dels quals era identificar les competències formatives dels professors en línia i les dels professos en línia. La llista de competències obtingudes posteriorment es va oferir als experts europeus que participaven en l'aplicació de la tècnica Delphi. A aquests experts se'ls va demanar que ordenessin les competències d'acord amb el seu grau d'importància.Els resultats mostren que els grups de discussió en línia i el mètode Delphi són les metodologies apropiades per a identificar les competències TIC dels professors universitaris en els entorns d'aprenentatge en línia.
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In the wake of the success of Peer-to-Peer (P2P) networking, security has arisen as one of its main concerns, becoming a key issue when evaluating a P2P system. Unfortunately, some systems' design focus targeted issues such as scalabil-ity or overall performance, but not security. As a result, security mechanisms must be provided at a later stage, after the system has already been designed and partially (or even fully) implemented, which may prove a cumbersome proposition. This work exposes how a security layer was provided under such circumstances for a specic Java based P2P framework: JXTA-Overlay.
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The objective of this work was to evaluate the growth of the mangrove oyster Crassostrea gasar cultured in marine and estuarine environments. Oysters were cultured for 11 months in a longline system in two study sites - São Francisco do Sul and Florianópolis -, in the state of Santa Catarina, Southern Brazil. Water chlorophyll-α concentration, temperature, and salinity were measured weekly. The oysters were measured monthly (shell size and weight gain) to assess growth. At the end of the culture period, the average wet flesh weight, dry flesh weight, and shell weight were determined, as well as the distribution of oysters per size class. Six nonlinear models (logistic, exponential, Gompertz, Brody, Richards, and Von Bertalanffy) were adjusted to the oyster growth data set. Final mean shell sizes were higher in São Francisco do Sul than in Florianópolis. In addition, oysters cultured in São Francisco do Sul were more uniformly distributed in the four size classes than those cultured in Florianópolis. The highest average values of wet flesh weight and shell weight were observed in São Francisco do Sul, whereas dry flesh weight did not differ between the sites. The estuary environment is more promising for the cultivation of oysters.
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The objective of this work was to estimate the repeatability of adaptability and stability parameters of common bean between years, within each biennium from 2003 to 2012, in Minas Gerais state, Brazil. Grain yield data from trials of value for cultivation and use common bean were analyzed. Grain yield, ecovalence, regression coefficient, and coefficient of determination were estimated considering location and sowing season per year, within each biennium. Subsequently, a analysis of variance these estimates was carried out, and repeatability was estimated in the biennia. Repeatability estimate for grain yield in most of the biennia was relatively high, but for ecovalence and regression coefficient it was null or of small magnitude, which indicates that confidence on identification of common bean lines for recommendation is greater when using means of yield, instead of stability parameters.
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The objective of this work was to identify by biometric analyses the most stable soybean parents, with higher oil or protein contents, cultivated at different seasons and locations of the state of Minas Gerais, Brazil. Forty-nine genotypes were evaluated in the municipalities of Viçosa, Visconde do Rio Branco, and São Gotardo, in the state of Minas Gerais, from 2009 to 2011. Protein and oil contents were analyzed by infrared spectrometry using a FT-NIR analyzer. The effects of genotype, environment, and genotype x environment interaction were significant. The BARC-8 soybean genotype is the best parent to increase protein contents in the progenies, followed by BR 8014887 and CS 3032PTA276-3-4. Selection for high oil content is more efficient when the crossings involve the Suprema, CD 01RR8384, and A7002 genotypes, which show high mean phenotypic values, wide adaptability, and greater stability to environmental variation.
Resumo:
To optimally manage a metapopulation, managers and conservation biologists can favor a type of habitat spatial distribution (e.g. aggregated or random). However, the spatial distribution that provides the highest habitat occupancy remains ambiguous and numerous contradictory results exist. Habitat occupancy depends on the balance between local extinction and colonization. Thus, the issue becomes even more puzzling when various forms of relationships - positive or negative co-variation - between local extinction and colonization rate within habitat types exist. Using an analytical model we demonstrate first that the habitat occupancy of a metapopulation is significantly affected by the presence of habitat types that display different extinction-colonization dynamics, considering: (i) variation in extinction or colonization rate and (ii) positive and negative co-variation between the two processes within habitat types. We consequently examine, with a spatially explicit stochastic simulation model, how different degrees of habitat aggregation affect occupancy predictions under similar scenarios. An aggregated distribution of habitat types provides the highest habitat occupancy when local extinction risk is spatially heterogeneous and high in some places, while a random distribution of habitat provides the highest habitat occupancy when colonization rates are high. Because spatial variability in local extinction rates always favors aggregation of habitats, we only need to know about spatial variability in colonization rates to determine whether aggregating habitat types increases, or not, metapopulation occupancy. From a comparison of the results obtained with the analytical and with the spatial-explicit stochastic simulation model we determine the conditions under which a simple metapopulation model closely matches the results of a more complex spatial simulation model with explicit heterogeneity.
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In this paper address we the question as to why participants tend to respond realistically to situations and events portrayed within an Immersive Virtual Reality (IVR) system. The idea is put forward, based on experience of a large number of experimental studies, that there are two orthogonal components that contribute to this realistic response. The first is"being there", often called"presence", the qualia of having a sensation of being in a real place. We call this Place Illusion (PI). Second, Plausibility Illusion (Psi) refers to the illusion that the scenario being depicted is actually occurring. In the case of both PI and Psi the participant knows for sure that that they are not"there" and that the events are not occurring. PI is constrained by the sensorimotor contingencies afforded by the virtual reality system. Psi is determined by the extent to which the system can produce events that directly relate to the participant, and the overall credibility of the scenario being depicted in comparison with expectations. We argue that when both PI and Psi occur, participants will respond realistically to the virtual reality.
Resumo:
This paper presents the use of our multimodal mixed reality telecommunication system to support remote acting rehearsal. The rehearsals involved two actors, located in London and Barcelona, and a director in another location in London. This triadic audiovisual telecommunication was performed in a spatial and multimodal collaborative mixed reality environment based on the 'destination-visitor' paradigm, which we define and put into use. We detail our heterogeneous system architecture, which spans the three distributed and technologically asymmetric sites, and features a range of capture, display, and transmission technologies. The actors' and director's experience of rehearsing a scene via the system are then discussed, exploring successes and failures of this heterogeneous form of telecollaboration. Overall, the common spatial frame of reference presented by the system to all parties was highly conducive to theatrical acting and directing, allowing blocking, gross gesture, and unambiguous instruction to be issued. The relative inexpressivity of the actors' embodiments was identified as the central limitation of the telecommunication, meaning that moments relying on performing and reacting to consequential facial expression and subtle gesture were less successful.