Many-body effects on the ρxx\rho_{xx} ringlike structures in two-subband wells

The longitudinal resistivity $\rho_{xx}$ of two-dimensional electron gases formed in wells with two subbands displays ringlike structures when plotted in a density--magnetic-field diagram, due to the crossings of spin-split Landau levels (LLs) from distinct subbands. Using spin density functional theory and linear response, we investigate the shape and spin polarization of these structures as a function of temperature and magnetic-field tilt angle. We find that (i) some of the rings "break" at sufficiently low temperatures due to a quantum Hall ferromagnetic phase transition, thus exhibiting a high degree of spin polarization ($\sim 50$%) within, consistent with the NMR data of Zhang \textit{et al.} [Phys. Rev. Lett. {\bf 98}, 246802 (2007)], and (ii) for increasing tilting angles the interplay between the anticrossings due to inter-LL couplings and the exchange-correlation (XC) effects leads to a collapse of the rings at some critical angle $\theta_c$, in agreement with the data of Guo \textit{et al.} [Phys. Rev. B {\bf 78}, 233305 (2008)].Comment: 4 pages, 3 figure

Dimensionality of the Iowa-Netherlands Comparison Orientation Measure and its relationship to Reinforcement Sensitivity Theory

The aims of this study were, first, to reassess the factor structure of the Iowa-Netherlands Social Comparison Orientation Measure (INCOM) and, second, to explore the associations of its factors with the Reinforcement Sensitivity Theory (RST) of personality. Data from 337 respondents were collected via online questionnaire. Structural equation models were used to assess the factor structure of the INCOM and test for relationships with RST traits. The results confirmed previous findings that the INCOM contains two factors: Ability, which relates to the comparison of performance, and Opinion, which relates to the comparison of thoughts and emotions. The two-factor model was found to be superior to the commonly used 1-factor solution. The models further revealed significant relationships with RST factors: positive associations between the Ability factor and the Behavioral Inhibition System (BIS) and Behavioural Approach System (BAS) Reward Reactivity; positive associations between the Opinion factor and BAS Reward Reactivity and Goal-Drive Persistence, and a negative association with BAS Impulsivity. These findings indicate that using the INCOM as a single scale is likely to miss significant unique relationships. Our findings also provide new insight into how individual differences in personality may influence social comparison behavior

Local dimension and finite time prediction in spatiotemporal chaotic systems

We show how a recently introduced statistics [Patil et al, Phys. Rev. Lett. 81 5878 (2001)] provides a direct relationship between dimension and predictability in spatiotemporal chaotic systems. Regions of low dimension are identified as having high predictability and vice-versa. This conclusion is reached by using methods from dynamical systems theory and Bayesian modelling. We emphasize in this work the consequences for short time forecasting and examine the relevance for factor analysis. Although we concentrate on coupled map lattices and coupled nonlinear oscillators for convenience, any other spatially distributed system could be used instead, such as turbulent fluid flows.Comment: 5 pagers, 7 EPS figure

Ariel - Volume 1 Number 3

Copyright 1969 Arie

Passive and Active Facebook Use Measure (PAUM): Validation and relationship to the Reinforcement Sensitivity Theory

The aims of this study were to design and validate a questionnaire to measure passive and active Facebook use, and to explore the associations of these factors with the Reinforcement Sensitivity Theory (RST) of personality. Passive Facebook use describes the consumption but not the creation of content, while active Facebook use describes active engagement with the site. As Facebook has many features, users may interact with the site differently, thereby creating conflicting results when general use measures are assessed independently. To address this issue, we developed a 13-item questionnaire which reflects three levels of Facebook engagement: Active social, Active non-social, and Passive use. These three multi-item scales demonstrate sufficient internal reliability and discriminant validity. To further investigate individual differences in Facebook use, we used regressions to assess the associations between RST and the factors of the Passive Active Use Measure (PAUM). Reward Reactivity was positively associated with both Active social and Passive use. Impulsivity and Goal-Drive Persistence were positively associated with Active non-social use. FFFS was positively associated with Passive use, and Reward Interest was positively associated with all three PAUM factors. The findings of this study highlight how individual differences impact the way users engage with Facebook

Subjective well-being and social media use: Do personality traits moderate the impact of social comparison on Facebook?

The purpose of the study was to explore whether personality traits moderate the association between social comparison on Facebook and subjective well-being, measured as both life satisfaction and eudaimonic well-being. Data were collected via an online questionnaire which measured Facebook use, social comparison behavior and personality traits for 337 respondents. The results showed positive associations between Facebook intensity and both measures of subjective well-being, and negative associations between Facebook social comparison and both measures of subjective well-being. Personality traits were assessed by the Reinforcement Sensitivity Theory personality questionnaire, which revealed that Reward Interest was positively associated with eudaimonic well-being, and Goal-Drive Persistence was positively associated with both measures of subjective well-being. Impulsivity was negatively associated with eudaimonic well-being and the Behavioral Inhibition System was negatively associated with both measures of subjective well-being. Interactions between personality traits and social comparison on Facebook indicated that for respondents with high Goal-Drive Persistence, Facebook social comparison had a positive association with eudaimonic well-being, thus confirming that some personality traits moderate the association between Facebook social comparison and subjective well-being. The results of this study highlight how individual differences in personality may impact how social comparison on Facebook affects individuals’ subjective well-being

Determinação da infecção do papilomavírus humano por captura híbrida II : correlação com achados morfológicos

O HPV é causa essencial, mas não suficiente, para o desenvolvimento de lesões pré-neoplásicas e neoplásicas do colo uterino. Sua identificação é fundamental para a avaliação de risco, sendo que o método de Captura Híbrida® apresenta reconhecida eficácia para esse fim. Por sua vez, os métodos morfológicos, colposcopia, citologia e histopatologia, demonstram as alterações celulares e tissulares sugestivas da ação desse vírus. Objetivo: comparar o desempenho dos métodos morfológicos, colposcopia, citologia e histopatologia, sugestivos de infecção pelo HPV, com o teste da Captura Híbrida® II (CHII). Métodos: analisaram-se 2.871 amostras cervicovaginais consecutivas de pacientes com suspeita de infecção pelo HPV em pelo menos um dos métodos morfológicos de diagnóstico. A coleta da amostra para o estudo biomolecular foi feita conforme as recomendações do fabricante, utilizando-se a escova cervical e o STM (specimen collection medium) como meio de preservação, tanto para o DNA quanto para o RNA. A CHII foi realizada utilizando-se sondas complementares de RNA para pool de vírus considerados de baixo risco (6, 11, 42, 43 e 44) e para aqueles de alto risco oncogênico (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68). A sensibilidade, a especificidade, a acurácia e os valores preditivos negativos e positivos dos métodos morfológicos foram determinados considerando-se o método biomolecular como padrão-ouro. Resultados: em 1.761 casos com diagnóstico colposcópico sugestivo de infecção pelo HPV, não se identificou a presença de DNA viral. A especificidade da colposcopia foi de 14,5%, a sensibilidade de 88,9%, a acurácia de 35,5% e os valores preditivos negativo (VPN) e positivo (VPP) de 76,9% e 29,1%, respectivamente. A citologia sugeriu corretamente HPV em 503 casos com especificidade de 56%, sensibilidade de 62%, acurácia de 57,7%, VPN de 78,9% e VPP de 35,7%. O estudo histopatológico apresentou 709 casos com suspeita de alteração HPV-induzida confirmados pela determinação biomolecular, mostrando na análise estatística especificidade de 15,1%, sensibilidade de 87,4%, acurácia de 35,6%, VPN de 75,4% e VPP de 28,9%. Juntos, os métodos morfológicos apresentaram sensibilidade de 94,1%, especificidade de 10,3% e acurácia de 34%. Conclusão: entre os exames morfológicos, a citologia, apesar de baixa, mostrou o melhor desempenho. A sensibilidade aumenta com a associação dos métodos morfológicos, mas, com isso, a especificidade fica reduzida e observa-se grande o número de resultados falso-positivos. Por isso, a suspeita morfológica de infecção pelo HPV deve ser confirmada por método biomolecular.HPV is a necessary but not sufficient cause for cervical cancer. Its crucial identifies HPV infection to establish the risk of cervical lesion. The Hybrid Capture (HCII) is recognized as method of choice to be used in routine conditions. Morphological methods (colposcopy, cytology and histopathology), are very specific to demonstrate HPV-induced lesions. Objective: to compare the performance of morphological methods to suggest HPV with HC II. Methods: 2871 consecutive samples, previously HPV infection suggested by colposcopy and/or cytology and/or histopathology, were submitted for HCII assay with high risk HPV probes (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68). Sensitivity, specificity, accuracy and negative (NPV) and positive (PPV) predictive values were calculated taking in account the HCII results as gold standard. Results: we did not identified HPV infection with HCII in 1.761 cases with colposcopic diagnosis suggestive of HPV infection, The colposcopy specificity was 14.5%, the sensitivity 88.9%, the accuracy 35.5% and the Negative (NPV) and Positive (PPV) predictive values were 76.9% and 29.1%, respectively. Cytology correctly suggested HPV in 503 cases with specificity of 56%, sensitivity of 62.0%, accuracy of 57.7% and NPV and PPV of 78.9% and 35.7%, respectively. Histopathological diagnosis showed 709 cases suggestive of HPV-induced lesion confirmed by HCII, resulting in specificity of 15.1%, sensitivity of 87.4%, accuracy of 35.6% and NPV and PPV of 75.4% and 28.9%, respectively. Together, morphological methods showed a sensitivity of 94.1%, specificity of 10.3%, and accuracy of 34.0%. Conclusion: among the morphological methods, despite its poor performance, cytology showed the best parameters to identify HPV infection. The sensitivity, but not the specificity, was improved with the morphological methods association. By that reason, biomolecular methods are required to confirm suspected morphological HPV infection

Effects of Photomixotrophic Conditions on Plants of Eucalyptus Urograndis Propagated in Temporary Immersion Bioreactors

Eucalyptus is one of the crop, which has been investigated with commercial purposes in the world. There are more than 500 species, being the Eucalyptus urograndis one of the most important, because of its intensive use in the production of wood pulp to make papers. The multiplication by means of temporary immersion bioreactors (TIB) is among the present techniques to obtain higher productions of the pulp to satisfy the demands of the market. The effects of the photomixotrophic crop were studies during the elongation of the propagation of shoots in the TIB in order to increase the quality of them. This process consisted of the use of 30 g L-1 combined with two concentration of CO2 (350 and 1200 µmol mol) and two flows of photosynthetic photon flux (PPF= 80 and 250 µmol m-2s-1). The higher percentage of suitable plants were found with the treatment of high PPF (250 µmol m-2 s-1) and 1 200 µmol mol of CO2. The photosynthetic capacity of propagated shoots was of 64% of the adult plants. Also was observed that photomixotrophic conditions reduced the stressed environment that is imposed by the growing in vitro. The catabolic activity in the enzymes of the metabolism of carbon was also reduced, increasing the activity of the Sucrose Phosphate Synthase