Construction of the B88 exchange-energy functional in two dimensions

We construct a generalized-gradient approximation for the exchange-energy density of finite two-dimensional systems. Guided by non-empirical principles, we include the proper small-gradient limit and the proper tail for the exchange-hole potential. The observed performance is superior to that of the two-dimensional local-density approximation, which underlines the usefulness of the approach in practical applications

Clinical, psychological and quality of life differences in fibromyalgia patients from secondary and tertiary healthcare

Background: The 'funnel effect' of Fibromyalgia (FM) assumes that as patients access healthcare services, they present greater severity and a more complex clinical situation than individuals with FM from the general population, but the studies comparing patients treated in different levels of healthcare are scarce. The aim of this study was to analyse the 'funnel effect' hypothesis by comparing patients from secondary and tertiary healthcare services. Methods: A cross-sectional sample of female patients was selected in secondary (rheumatology practices - RP) and in tertiary healthcare (chronic pain clinics - CPC). Information about sociodemographic, clinical and psychological characteristics was collected and health related quality of life (HRQL) was assessed. Results: In total, 55 patients from RP and 60 patients from CPC were included in the comparison. Patients from CPC revealed a worst clinical status (higher number of tender points, medical visits and comorbidity), more somatic symptoms (pain and daytime dysfunction levels) and worst emotional status (more anxiety) than patients from RP. Patients attending CPC also revealed a worst HRQL than RP patients although this difference was mediated by the differences in clinical and psychological variables. Conclusions: Our study supports the 'funnel effect' hypothesis among patients of different healthcare levels, with patients from tertiary healthcare services revealing worst clinical status, more somatic and psychological symptoms, and worst HRQL than patients from secondary healthcare services. Significance: The worst clinical and psychological status and poorer quality of life in the patients from tertiary healthcare (chronic pain clinics) in relation to the patients from secondary healthcare (rheumatology practices) must be taken into account to design studies that assess any of these aspects, to a proper analysis and interpretation of the data, and to define the scope of its generalization, as data from different clinical settings are not directly comparable

On the violation of a local form of the Lieb-Oxford bound

In the framework of density-functional theory, several popular density functionals for exchange and correlation have been constructed to satisfy a local form of the Lieb-Oxford bound. In its original global expression, the bound represents a rigorous lower limit for the indirect Coulomb interaction energy. Here we employ exact-exchange calculations for the G2 test set to show that the local form of the bound is violated in an extensive range of both the dimensionless gradient and the average electron density. Hence, the results demonstrate the severity in the usage of the local form of the bound in functional development. On the other hand, our results suggest alternative ways to construct accurate density functionals for the exchange energy.Comment: (Submitted on 27 April 2012

Resonant Orbital Dynamics in LEO Region: Space Debris in Focus

The increasing number of objects orbiting the earth justifies the great attention and interest in the observation, spacecraft protection, and collision avoidance. These studies involve different disturbances and resonances in the orbital motions of these objects distributed by the distinct altitudes. in this work, objects in resonant orbital motions are studied in low earth orbits. Using the two-line elements (TLE) of the NORAD, resonant angles and resonant periods associated with real motions are described, providing more accurate information to develop an analytical model that describes a certain resonance. the time behaviors of the semimajor axis, eccentricity, and inclination of some space debris are studied. Possible irregular motions are observed by the frequency analysis and by the presence of different resonant angles describing the orbital dynamics of these objects.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo UNIFESP, BR-12231280 Sao Jose Dos Campos, SP, BrazilAstron Observ, AMU, PL-60286 Poznan, PolandITA, BR-12228900 Sao Jose Dos Campos, SP, BrazilUniversidade Federal de São Paulo UNIFESP, BR-12231280 Sao Jose Dos Campos, SP, BrazilFAPESP: 2012/24369-0FAPESP: 2012/21023-6CNPq: 303070/2011-0Web of Scienc

Screening for Autism Spectrum Disorders-Validation of the Portuguese Version of the Social Communication Questionnaire

There are no assessment and screening tools for Autism Spectrum Disorders (ASD) validated for the Portuguese population. The Social Communication Questionnaire (SCQ) is an useful screening tool of ASD diagnosis. The main objectives of our study were to produce a Portuguese version of the SCQ (SCQ-PF), study its internal consistency, sensitivity and specificity in order to evaluate its validity as a screening instrument for ASD. We also wanted to study the impact of intellectual disability and verbal impairment and other mental disorders on SCQ-PF psychometric properties. The study included 211 children and adolescents, aged 4-17, divided in three groups: ASD Group (n = 96), Other Mental Disorders Group (OMD) (n = 63) and No Mental Disorders (NMD) Group (n = 52). Parents or other primary caregiver provided information on the SCQ items. The SCQ-PF score was significantly higher in the ASD group than in the other groups (p < 0.001). As to internal consistency, Cronbach's alpha was 87%. ASD subjects were distinguished from subjects without ASD (OMD and NMD Groups) and the area under the curve (AUC) was 0.897 (95% Confidence Interval: 0.852-0.943), for a cutoff of 14, which yielded the highest AUC, with values of sensitivity and specificity 0.76 and 0.93, respectively. These findings show that SCQ- PF with a cutoff of 14 is an acceptable and useful screening tool for ASD in the Portuguese population