22 resultados para 1477


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Reasoning about problems with empirically false content can be hard, as the inferences that people draw are heavily influenced by their background knowledge. However, presenting empirically false premises in a fantasy context helps children and adolescents to disregard their beliefs, and to reason on the basis of the premises. The aim of the present experiments was to see if high-functioning adolescents with autism are able to utilize fantasy context to the same extent as typically developing adolescents when they reason about empirically false premises. The results indicate that problems with engaging in pretence in autism persist into adolescence, and this hinders the ability of autistic individuals to disregard their beliefs when empirical knowledge is irrelevant.

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We propose transmit antenna selection with receive generalized selection combining (TAS/GSC) in dual-hop cognitive decode-and-forward (DF) relay networks for reliability enhancement and interference relaxation. In this paradigm, a single antenna which maximizes the receive signal-to-noise ratio (SNR) is selected at the secondary transmitter and a subset of receive antennas with the highest SNRs are combined at the secondary receiver. To demonstrate the impact of multiple primary users on the cognitive relay network, we derive new closed-form expressions for the exact and asymptotic outage probability with TAS/GSC in the secondary network. Several important design insights are reached. We corroborate that the full diversity gain is achieved, which is entirely determined by the total number of antennas in the secondary network. The negative impact of the primary network on the secondary network is reflected in the SNR gain.

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Parametric interactions in nonlinear crystals represent a powerful tool in the optical manipulation of information, both in the classical and the quantum regime. Here, we analyze in detail classical and quantum aspects of three-and five-mode parametric interactions in chi(2) nonlinear crystals. The equations of motion are explicitly derived and then solved within the parametric approximation. We describe several applications, including holography, all-optical gates, generation of entanglement, and telecloning. Experimental results on the photon distributions and correlations of the generated beams are also reported and discussed.

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In acne vulgaris, antimicrobial peptides (AMPs) could play a dual role; i.e., protective by acting against Propionibacterium acnes, pro-inflammatory by acting as signalling molecules. The cutaneous expression of 15 different AMPs was investigated in acne patients; furthermore, the impact of isotretinoin therapy on AMP expression was analysed in skin biopsies from 13 patients with acne vulgaris taken before, during and after a 6-month treatment cycle with isotretinoin using quantitative real-time polymerase chain reaction. Cutaneous expression of the AMPs cathelicidin, human β-defensin-2 (HBD-2), lactoferrin, lysozyme, psoriasin (S100A7), koebnerisin (S100A15), and RNase 7 was upregulated in untreated acne vulgaris, whereas α-defensin-1 (HNP-1) was downregulated compared to controls. While relative expression levels of cathelicidin, HBD-2, lactoferrin, psoriasin (S100A7), and koebnerisin (S100A15) decreased during isotretinoin treatment, only those of cathelicidin and koebnerisin returned to normal after 6 months of isotretinoin therapy. The increased expression of lysozyme and RNase 7 remained unaffected by isotretinoin treatment. The levels of granulysin, RANTES (CCL5), perforin, CXCL9, substance P, chromogranin B, and dermcidin were not regulated in untreated acne patients and isotretinoin had no effect on these AMPs. In conclusion, the expression of various AMPs is altered in acne vulgaris. Isotretinoin therapy normalizes the cutaneous production of distinct AMPs while the expression of others is still increased in healing acne. Considering the antimicrobial and pro-inflammatory role of AMPs, these molecules could serve as specific targets for acne therapy and maintenance of clinical remission.

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In this paper we compare conceptualising single factor technical and allocative efficiency as indicators of a single latent variable, or as separate observed variables. In the former case, the impacts on both efficiency types are analysed by means of structural equation modeling (SEM), in the latter by seemingly unrelated regression (SUR). We compare estimation results of the two approaches based on a dataset on single factor irrigation water use efficiency obtained from a survey of 360 farmers in the Guanzhong Plain, China. The main methodological findings are that SEM allows identification of the most important dimension of irrigation water efficiency (technical efficiency) via comparison of their factor scores and reliability. Moreover, it reduces multicollinearity and attenuation bias. It thus is preferable to SUR. The SEM estimates show that perception of water scarcity is the most important positive determinant of both types of efficiency, followed by irrigation infrastructure, income and water price. Furthermore, there is a strong negative reverse effect from efficiency on perception.

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PURPOSE: To evaluate the hypothesis that changes in nutritional status could be partly responsible for observed increases in myopia prevalence among Chinese children. DESIGN: Cross-sectional cohort study. METHODS: Rural Chinese secondary school children participating in a study of interventions to promote spectacle use were randomly sampled (20% of children with uncorrected vision >6/12 bilaterally, and 100% of remaining children) and underwent cycloplegic refraction with subjective refinement and measurement of height and weight. Stunting was defined according to the World Health Organization standard population. RESULTS: Among 3226 children in the sample, 2905 (90.0%) took part. Among 1477 children undergoing refraction, 1371 (92.8%) had height and weight measurements. These children had a mean age of 14.5 +/- 1.4 years, 59.8% were girls, and mean spherical equivalent refraction was -1.93 +/- 1.82 diopters. Stunting was present in 87 children (6.4%). While height was inversely associated with refractive error (RE) (taller children were more myopic) among boys (r = -0.147, P = .001), this disappeared when adjusting for age, and no such association was observed among girls. Neither girls nor boys with stunting differed significantly in refraction from children without stunting, and neither stunting nor height was associated with RE when adjusting for age, height, and parental education. The power of this study to have detected a 0.75 diopters difference in RE between children with and without stunting was 0.96. CONCLUSION: Results from this cross-sectional study are not consistent with the hypothesis that nutritional status is a determinant of RE in this setting.

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Genetically engineered (GE) crops are subject to regulatory oversight to ensure their safety for humans and the environment. Their approval in the European Union (EU) starts with an application in a given Member State followed by a scientific step (risk assessment), and ends with a political decision-making step (risk management); and in the United States (US) it starts with a scientific (field trial) step and ends with a ‘bureaucratic’ decision-making step. We investigated trends for the time taken for these steps and the overall time taken for approving GE crops in the US and the EU (traders in these commodities). Results show that from 1996-2015 the overall time trend for approval in the EU decreased and then flattened off, with an overall mean completion-time of 1,763 days. In the US in 1998 there was a break in the trend of the overall approval time: Initially, from 1988 until 1997 the trend decreased with a mean approval time of 1,321 days; from 1998-2015, the trend almost stagnated with a mean approval time of 2,467 days.