bluuebunny/crossref_metadata_2025 huggingface dataset:
An Adjoint State Method for Numerical Approximation of Continuous Traffic Congestion Equilibria
Authors: Luo Songting , Leung Shingyu , Qian Jianliang
Published: August 2011

The equilibrium metric for minimizing a continuous congested traffic model is the solution of a variational problem involving geodesic distances. The continuous equilibrium metric and its associated variational problem are closely related to the classical discrete Wardrop’s equilibrium. We propose an adjoint state method to numerically approximate continuous traffic congestion equilibria through the continuous formulation. The method formally derives an adjoint state equation to compute the gradient descent direction so as to minimize a nonlinear functional involving the equilibrium metric and the resulting geodesic distances. The geodesic distance needed for the state equation is computed by solving a factored eikonal equation, and the adjoint state equation is solved by a fast sweeping method. Numerical examples demonstrate that the proposed adjoint state method produces desired equilibrium metrics and outperforms the subgradient marching method for computing such equilibrium metrics.
A High Order Spectral Volume Formulation for Solving Equations Containing Higher Spatial Derivative Terms: Formulation and Analysis for Third Derivative Spatial Terms Using the LDG Discretization Procedure
Authors: Kannan Ravi
Published: August 2011

In this paper, we develop a formulation for solving equations containing higher spatial derivative terms in a spectral volume (SV) context; more specifically the emphasis is on handling equations containing third derivative terms. This formulation is based on the LDG (Local Discontinuous Galerkin) flux discretization method, originally employed for viscous equations containing second derivatives. A linear Fourier analysis was performed to study the dispersion and the dissipation properties of the new formulation. The Fourier analysis was utilized for two purposes: firstly to eliminate all the unstable SV partitions, secondly to obtain the optimal SV partition. Numerical experiments are performed to illustrate the capability of this formulation. Since this formulation is extremely local, it can be easily parallelized and a h-p adaptation is relatively straightforward to implement. In general, the numerical results are very promising and indicate that the approach has a great potential for higher dimension Korteweg-de Vries (KdV) type problems.
Resonance Clustering in Wave Turbulent Regimes: Integrable Dynamics
Authors: Bustamante Miguel D. , Kartashova Elena
Published: August 2011

Two fundamental facts of the modern wave turbulence theory are 1) existence of power energy spectra ink-space, and 2) existence of “gaps” in this spectra corresponding to the resonance clustering. Accordingly, three wave turbulent regimes are singled out:kinetic, described by wave kinetic equations and power energy spectra;discrete, characterized by resonance clustering; andmesoscopic, where both types of wave field time evolution coexist. In this review paper we present the results on integrable dynamics of resonance clusters appearing in discrete and mesoscopic wave turbulent regimes. Using a novel method based on the notion of dynamical invariant we show that some of the frequently met clusters are integrable in quadratures for arbitrary initial conditions and some others-only for particular initial conditions. We also identify chaotic behaviour in some cases. Physical implications of the results obtained are discussed.
The Approximate Solutions of FPK Equations in High Dimensions for Some Nonlinear Stochastic Dynamic Systems
Authors: Er Guo-Kang , Iu Vai Pan
Published: August 2011

The probabilistic solutions of the nonlinear stochastic dynamic (NSD) systems with polynomial type of nonlinearity are investigated with the subspace-EPC method. The space of the state variables of large-scale nonlinear stochastic dynamic system excited by white noises is separated into two subspaces. Both sides of the Fokker-Planck-Kolmogorov (FPK) equation corresponding to the NSD system is then integrated over one of the subspaces. The FPK equation for the joint probability density function of the state variables in another subspace is formulated. Therefore, the FPK equation in low dimensions is obtained from the original FPK equation in high dimensions and it makes the problem of obtaining the probabilistic solutions of large-scale NSD systems solvable with the exponential polynomial closure method. Examples about the NSD systems with polynomial type of nonlinearity are given to show the effectiveness of the subspace-EPC method in these cases.
Arquitetura da informação para biblioteca digital personalizável
Authors: Camargo Liriane Soares de Araújo de , Vidotti Silvana Ap. Borseti Gregório
Published: August 2011

Alguns recursos que podem minimizar dificuldades em relação à recuperação e disseminação de informações são: bibliotecas digitais, que possuem acesso simultâneo e remoto às informações de forma eficiente; e serviços de personalização, que permite ao usuário uma interação personalizada baseada no seu perfil. O problema de prover esses recursos se encontra na onerosidade e na dificuldade do processo de desenvolvimento, devido à grande quantidade de processos e elementos envolvidos em sua construção. Nesse contexto, é proposta uma arquitetura da informação para bibliotecas digitais personalizáveis, que visa a tratar dos seguintes problemas: escassez de literatura especializada; falta de elementos tecnológicos e informacionais, e pouca utilização de serviços de personalização de conteúdo e de interface para diversos tipos de usuários.
Uma proposta de metodologia para indexação automática utilizando sintagmas nominais
Authors: Souza Renato Rocha
Published: August 2011

Com o aparente esgotamento das estratégias atuais de representação e indexação de documentos, faz-se necessário investigar novas abordagens para sistemas de recuperação de informações. Dentre estas abordagens, há uma vertente que busca levar em conta a semântica intrínseca aos documentos textuais, e uma das formas de fazê-lo é através da utilização de sintagmas nominais como descritores, ao invés de palavras-chave. Uma metodologia para atingir tal propósito, desenvolvida no escopo de uma tese de doutorado, é apresentada neste artigo.
Disseminação seletiva de informações: discussão de modelos eletrônicos
Authors: Souto Leonardo Fernandes
Published: August 2011

A partir de uma visão interacionista, a pesquisa concentra-se na caracterização e análise de modelos eletrônicos de Disseminação Seletiva de Informações (SDI). Nesse sentido, buscou-se, primeiramente, identificar abordagens sobre o papel da tecnologia nos serviços oferecidos por Unidades de Informação. A perspectiva interacionista, adotada, fundamenta-se no conceito de interação proposto por Turner e na concepção de linguagem de Bakhtin. A revisão de literatura sobre a prática da Disseminação Seletiva de Informações fornece uma visão geral do SDI, seus objetivos e funcionamento. A partir desses referenciais, foram determinados 3 parâmetros para a análise do SDI - preenchimento do perfil de interesse, representação da informação e uso de canais de interação, os quais foram aplicados para analisar, de forma exploratória, 6 serviços eletrônicos de SDI, selecionados aleatoriamente. Esta aplicação permitiu refinar e desenvolver uma proposta de SDI interacionista.
Uso de fontes de informação para a inteligência competitiva: um estudo da influência do porte das empresas sobre o comportamento informacional
Authors: Barbosa Ricardo Rodrigues
Published: August 2011

O trabalho relata uma pesquisa sobre o uso e a avaliação de fontes de informação a respeito do ambiente organizacional externo em 53 empresas de pequeno porte e em 64 grandes empresas. Os resultados revelaram que, em comparação com profissionais de pequenas empresas, os profissionais que trabalham em empresas de grande porte lêem, com maior freqüência, jornais e revistas em papel. Da mesma forma, eles utilizam mais fontes documentais internas, como memorandos e circulares. O acesso a fontes pessoais internas (superiores e subordinados hierárquicos e colegas) também é maior junto aos profissionais de grandes empresas. Quanto ao grau de confiabilidade das fontes, os que trabalham em empresas de grande porte consideram mais confiáveis as fontes governamentais (na forma de publicações e de seus representantes) do que aqueles ligados a pequenas empresas.
Un modelo de evaluación de la calidad de las bibliotecas universitarias digitales basado en técnicas difusas
Authors: Herrera-Viedma S. Alonso E. , Ávila Javier López Gijón B. , Pardo Josefina Vílchez
Published: August 2011

Se presenta un modelo para la evaluación de la calidad de las bibliotecas universitarias digitales basado en técnicas difusas. El modelo contiene tanto criterios objetivos como subjetivos. Usa información difusa lingüística para la representación de las valores de calidad y operadores de agregación de información lingüística para obtenerlos.
La biblioteca universitaria como apoyo al aprendizaje en el espacio europeo de enseñanza superior
Authors: Gijón Javier López , López Ana Pérez , Gálvez Carmen , Caro Concepción García
Published: August 2011

La biblioteca universitaria se encuentra en un proceso de transformación ante el Espacio Europeo de Educación Superior (EEES). Este nuevo marco implica básicamente un cambio en el modelo de enseñanza, centrado en el aprendizaje y basado en una serie de competencias que convierten al estudiante en protagonista de su propio aprendizaje. Este cambio en el paradigma docente integra las Tecnologías de la Información y Comunicación (TICs), así como los planteamientos e-learning y la alfabetización digital, en los futuros modelos educativos. Para apoyar este cambio las bibliotecas universitarias deben adaptar sus espacios y servicios a las nuevas necesidades docentes, evolucionando a un Centro de Recursos para el Aprendizaje e Investigación (CRAI). En este trabajo se analizan los procesos de conversión de la biblioteca universitaria, y el nuevo papel de los bibliotecarios, ante las necesidades informativas que demanda la comunidad universitaria.
É possível falar em signo e semiose documentária?
Authors: Lara Marilda Lara Lopes Ginez de
Published: August 2011

São discutidas as contribuições da abordagem lingüístico-semiótica para a compreensão do funcionamento da linguagem documentária, bem como a possibilidade do signo e da semiose documentária. Apresenta-se uma síntese dos principais conceitos da semiótica – signo, objeto, interpretante, experiência colateral e semiose – e procura-se caracterizar o signo documentário e a semiose documentárias focando particularmente dois sistemas semióticos relacionados: a linguagem natural e a linguagem artificial. Conclui-se pela caracterização do signo documentário como um signo particular, cujo funcionamento depende do caráter construído da linguagem documentária e da remessa a interpretantes nos discursos e terminologias das áreas focalizadas.
O ícone e a possibilidade de informação
Authors: Moreira Solange Silva
Published: August 2011

Este artigo aborda a potencialidade informacional do signo icônico a partir da Semiótica de Charles Sanders Peirce, instrumento utilizado para tratar tanto do estatuto ontológico da informação – a sua inscrição na secundidade – como da sua presença no interior da tríade semiótica – na forma de objeto imediato do signo. A partir dessa abordagem verifica-se que a mera possibilidade, modo como a informação se apresenta em estado de primeiridade, é o elemento que vai caracterizar o ícone, o signo que se inscreve na primeira categoria.
Semiótica peirciana e a questão da informação e do conhecimento
Authors: Monteiro Silvana Drumond
Published: August 2011

Traz a teoria do signo no contexto da Semiótica peirciana. Após algumas discussões apresenta a diferença entre informação e conhecimento, tanto do ponto de vista da linguagem, como do sujeito cognoscente. Percebe-se, na literatura da área, uma incompletude na abordagem desses conceitos pelo desconhecimento de pressupostos teóricos da linguagem. A informação e o conhecimento, entendidos como manifestação lingüística, estão sujeitos a certos atributos que os caracterizam e os organizam, do ponto de vista da linguagem, ora em um, ora em outro. Conclui-se que o fenômeno do conhecimento na sociedade das mídias está organizado em discursos e materializados nas formas simbólicas, não sendo incorreto, portanto, falar em "organização do conhecimento".
Signos audiovisuais e ciência da informação: uma avaliação
Authors: Bethônico Jalver
Published: August 2011

Este trabalho avalia a relação da Ciência da Informação com os signos audiovisuais apontando as limitações conceituais, as dificuldades impostas pelo fundamento verbal do saber, o uso reduzido dentro das bibliotecas e os caminhos na direção de uma análise mais consistente dos meios audiovisuais, apoiada na Semiótica de Charles Peirce.
Tropospheric temperature response to stratospheric ozone recovery in the 21st century
Authors: Hu Y. , Xia Y. , Fu Q.
Published: August 2011

Abstract. Recent simulations predicted that the stratospheric ozone layer will likely return to pre-1980 levels in the middle of the 21st century, as a result of the decline of ozone depleting substances under the Montreal Protocol. Since the ozone layer is an important component in determining stratospheric and tropospheric-surface energy balance, the recovery of stratospheric ozone may have significant impact on tropospheric-surface climate. Here, using multi-model results from both the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC-AR4) models and coupled chemistry-climate models, we show that as ozone recovery is considered, the troposphere is warmed more than that without considering ozone recovery, suggesting an enhancement of tropospheric warming due to ozone recovery. It is found that the enhanced tropospheric warming is mostly significant in the upper troposphere, with a global and annual mean magnitude of ~0.41 K for 2001–2050. We also find that relatively large enhanced warming occurs in the extratropics and polar regions in summer and autumn in both hemispheres, while the enhanced warming is stronger in the Northern Hemisphere than in the Southern Hemisphere. Enhanced warming is also found at the surface. The global and annual mean enhancement of surface warming is about 0.16 K for 2001–2050, with maximum enhancement in the winter Arctic.
Estimating seasonal variations in cloud droplet number concentration over the boreal forest from satellite observations
Authors: Janssen R. H. H. , Ganzeveld L. N. , Kabat P. , Kulmala M. , Nieminen T. , Roebeling R. A.
Published: August 2011

Abstract. Seasonal variations in cloud droplet number concentration (NCD) in low-level stratiform clouds over the boreal forest are estimated from MODIS observations of cloud optical and microphysical properties, using a sub-adiabatic cloud model to interpret vertical profiles of cloud properties. An uncertainty analysis of the cloud model is included to reveal the main sensitivities of the cloud model. We compared the seasonal cycle in NCD, obtained using 9 yr of satellite data, to surface concentrations of potential cloud activating aerosols, measured at the SMEAR II station at Hyytiälä in Finland. The results show that NCD and cloud condensation nuclei (CCN) concentrations have no clear correlation at seasonal time scale. The fraction of aerosols that actually activate as cloud droplet decreases sharply with increasing aerosol concentrations. Furthermore, information on the stability of the atmosphere shows that low NCD is linked to stable atmospheric conditions. Combining these findings leads to the conclusion that cloud droplet activation for the studied clouds over the boreal forest is limited by convection. Our results suggest that it is important to take the strength of convection into account when studying the influence of aerosols from the boreal forest on cloud formation, although they do not rule out the possibility that aerosols from the boreal forest affect other types of clouds with a closer coupling to the surface.
A statistical analysis of North East Atlantic (submicron) aerosol size distributions
Authors: Dall'Osto M. , Monahan C. , Greaney R. , Beddows D. C. S. , Harrison R. M. , Ceburnis D. , O'Dowd C. D.
Published: August 2011

Abstract. The Global Atmospheric Watch research station at Mace Head (Ireland) offers the possibility to sample some of the cleanest air masses being imported into Europe as well as some of the most polluted being exported out of Europe. We present a statistical Cluster~analysis of the physical characteristics of aerosol size distributions in air ranging from the cleanest to the most polluted for the year 2008. Data coverage achieved was 75 % throughout the year. By applying the Hartigan-Wong k-Means method, 12 Clusters were identified as systematically occurring and these 12 Clusters could be further combined into 4 categories with similar characteristics, namely: coastal nucleation category (occurring 21.3 % of the time), open ocean nucleation category (occurring 32.6 % of the time), background clean marine category (occurring 26.1 % of the time) and anthropogenic category (occurring 20 % of the time) aerosol size distributions. The coastal nucleation category is characterised by a clear and dominant nucleation mode at sizes less that 10 nm while the open ocean nucleation category is characterised by a dominant Aitken mode between 15 nm and 50 nm. The background clean marine characteristic is a clear bimodality in the size distribution, although it should be noted that either the Aitken mode or the Accumulation mode may dominate the number concentration. By contrast, the continentally-influenced size distributions are generally more mono-modal, albeit with traces of bi-modality. The open ocean category occurs more often during May, June and July, corresponding with the N. E. Atlantic high biological period. Combined with the relatively high percentage frequency of occurrence (32.6 %), this suggests that the marine biota is an important source of new aerosol particles in N. E. Atlantic Air.
Reducing uncertainties associated with filter-based optical measurements of light absorbing carbon particles with chemical information
Authors: Engström J. E. , Leck C.
Published: August 2011

Abstract. The presented filter-based optical method for determination of soot (light absorbing carbon or Black Carbon, BC) can be implemented in the field under primitive conditions and at low cost. This enables researchers with small economical means to perform monitoring at remote locations, especially in the Asia where it is much needed. One concern when applying filter-based optical measurements of BC is that they suffer from systematic errors due to the light scattering of non-absorbing particles co-deposited on the filter, such as inorganic salts and mineral dust. In addition to an optical correction of the non-absorbing material this study provides a protocol for correction of light scattering based on the chemical quantification of the material, which is a novelty. A newly designed photometer was implemented to measure light transmission on particle accumulating filters, which includes an additional sensor recording backscattered light. The choice of polycarbonate membrane filters avoided high chemical blank values and reduced errors associated with length of the light path through the filter. Two protocols for corrections were applied to aerosol samples collected at the Maldives Climate Observatory Hanimaadhoo during episodes with either continentally influenced air from the Indian/Arabian subcontinents (winter season) or pristine air from the Southern Indian Ocean (summer monsoon). The two ways of correction (optical and chemical) lowered the particle light absorption of BC by 63 to 61 %, respectively, for data from the Arabian Sea sourced group, resulting in median BC absorption coefficients of 4.2 and 3.5 Mm−1. Corresponding values for the South Indian Ocean data were 69 and 97 % (0.38 and 0.02 Mm−1). A comparison with other studies in the area indicated an overestimation of their BC levels, by up to two orders of magnitude. This raises the necessity for chemical correction protocols on optical filter-based determinations of BC, before even the sign on the radiative forcing based on their effects can be assessed.
Volcanic impact on the Atlantic ocean over the last millennium
Authors: Mignot J. , Khodri M. , Frankignoul C. , Servonnat J.
Published: August 2011

Abstract. The oceanic response to volcanic eruptions over the last 1000 years is investigated with a focus on the North Atlantic Ocean, using a fully coupled AOGCM forced by a realistic time series of volcanic eruptions, total solar irradiance (TSI) and atmospheric greenhouse gases concentration. The model simulates little response to TSI variations but a strong and long-lasting thermal and dynamical oceanic adjustment to volcanic forcing, which is shown to be a function of the time period of the volcanic eruptions, probably due to their different seasonality. The thermal response consists of a fast tropical cooling due to the radiative forcing by the volcanic eruptions, followed by a penetration of this cooling in the subtropical ocean interior one to five years after the eruption, and propagation of the anomalies toward the high latitudes. The oceanic circulation first adjusts rapidly to low latitude anomalous wind stress induced by the strong cooling. The Atlantic Meridional Overturning Circulation (AMOC) shows a significant intensification 5 to 10 years after the eruptions of the period post-1400 AD, in response to anomalous atmospheric momentum forcing, and a slight weakening in the following decade. In response to the stronger eruptions occurring between 1100 and 1300, the AMOC shows no intensification and a stronger reduction after 10 years. This study thus stresses the diversity of AMOC response to volcanic eruptions in climate models and tentatively points to an important role of the seasonality of the eruptions.
Content analysis for Agricultural Records of the United Kingdom, AD 200 to 1977: a study of frequency in human records concerning climate phenomenon
Authors: Holt D. H.
Published: August 2011

Abstract. A content analysis has been completed on a text from the UK that has gathered agricultural and climate data from the years AD 220 to 1977 from 100s of sources. The content analysis coded all references to climate and agriculture to ascertain which climate events were recorded and which were not. This study addressed the question: is there bias in human records of climate? This evaluated the continuous record (AD 1654–1977), discontinous record (AD 220–1653), the whole record (AD 220–1977), the Little Climate Optimum (AD 850–1250) and the Little Ice Age (AD 1450–1880). This study shows that there is no significant variation in any of these periods in frequency occurrence of "good" or "bad" climate suggesting humans are not recording long-term changes in climate, but they are recording weather phenomenon as it occurs.
Partial Derivative Fitted Taylor Expansion: an efficient method for calculating gas/liquid equilibria in atmospheric aerosol particles – Part 2: Organic compounds
Authors: Topping D. , Lowe D. , McFiggans G.
Published: August 2011

Abstract. A flexible mixing rule is presented which allows the calculation of activity coefficients of organic compounds in a multi-component aqueous solution. Based on the same fitting methodology as a previously published inorganic model (Partial Differential Fitted Taylor series Expansion; PD-FiTE), organic PD-FiTE treats interactions between binary pairs of solutes with polynomials of varying order. Using 13 example compounds extracted from a recent sensitivity study, the framework is benchmarked against the UNIFAC model. For 1000 randomly derived concentration ranges and 10 relative humidities between 10 and 99 %, the average deviation in predicted activity coefficients was calculated to be 3.8 %. Whilst compound specific deviations are present, the median and inter-quartile values across all relative humidity range always fell within ±20 % of the UNIFAC value. Comparisons were made with the UNIFAC model by assuming interactions between solutes can be set to zero within PD-FiTE. In this case, deviations in activity coefficients as low as −40 % and as high as +70 % were found. Both the fully coupled and uncoupled organic PD-FiTE are upto a factor of ≈12 and ≈66 times more efficient than calling the UNIFAC model using the same water content, and ≈310 and ≈1800 times more efficient than an iterative model using UNIFAC. The use of PD-FiTE within a dynamical framework is presented, demonstrating the potential inaccuracy of prescribing fixed negative or positive deviations from ideality when modelling the evolving chemical composition of aerosol particles.
A Systematic and Evidence-Based Approach to the Management of Vertebral Metastasis
Authors: Jennelle Richard L. S. , Vijayakumar Vani , Vijayakumar Srinivasan
Published: August 2011

Diagnosis and management of vertebral metastasis requires a systematic approach to patient identification as well as selection of appropriate therapy. Rapid identification and prompt intervention in the treatment of malignant epidural spinal cord compression (MESCC) is key to maintaining quality of life. This paper provides a series of tools as well as guidance in selecting effective and evidence-based therapy individualized to the specific patient.
Community-Implemented Trauma Therapy for Former Child Soldiers in Northern Uganda
Authors: Ertl Verena , Pfeiffer Anett , Schauer Elisabeth , Elbert Thomas , Neuner Frank
Published: August 2011

Context

The psychological rehabilitation of former child soldiers and their successful reintegration into postconflict society present challenges. Despite high rates of impairment, there have been no randomized controlled trials examining the feasibility and efficacy of mental health interventions for former child soldiers.

Objective

To assess the efficacy of a community-based intervention targeting symptoms of posttraumatic stress disorder (PTSD) in formerly abducted individuals.

Design, Setting, and Participants

Randomized controlled trial recruiting 85 former child soldiers with PTSD from a population-based survey of 1113 Northern Ugandans aged 12 to 25 years, conducted between November 2007 and October 2009 in camps for internally displaced persons. Participants were randomized to 1 of 3 groups: narrative exposure therapy (n = 29), an academic catch-up program with elements of supportive counseling (n = 28), or a waiting list (n = 28). Symptoms of PTSD and trauma-related feelings of guilt were measured using the Clinician-Administered PTSD Scale. The respective sections of the Mini International Neuropsychiatric Interview were used to assess depression and suicide risk, and a locally adapted scale was used to measure perceived stigmatization. Symptoms of PTSD, depression, and related impairment were assessed before treatment and at 3 months, 6 months, and 12 months postintervention.

Intervention

Treatments were carried out in 8 sessions by trained local lay therapists, directly in the communities.

Main Outcome Measures

Change in PTSD severity, assessed over a 1-year period after treatment. Secondary outcome measures were depression symptoms, severity of suicidal ideation, feelings of guilt, and perceived stigmatization.

Results

PTSD symptom severity (range, 0-148) was significantly more improved in the narrative exposure therapy group than in the academic catch-up (mean change difference, −14.06 [95% confidence interval, −27.19 to −0.92]) and waiting-list (mean change difference, −13.04 [95% confidence interval, −26.79 to 0.72]) groups. Contrast analyses of the time × treatment interaction of the mixed-effects model on PTSD symptom change over time revealed a superiority of narrative exposure therapy compared with academic catch-up (F1,234.1 = 5.21, P = .02) and wait-listing (F1,228.3 = 5.28, P = .02). Narrative exposure therapy produced a larger within-treatment effect size (Cohen d = 1.80) than academic catch-up (d = 0.83) and wait-listing (d = 0.81).

Conclusion

Among former Ugandan child soldiers, short-term trauma-focused treatment compared either with an academic catch-up program including supportive counseling or with wait-listing resulted in greater reduction of PTSD symptoms.

Trial Registration

clinicaltrials.gov Identifier: NCT00552006
Adjunctive Risperidone Treatment for Antidepressant-Resistant Symptoms of Chronic Military Service–Related PTSD
Authors: Krystal John H. , Rosenheck Robert A. , Cramer Joyce A. , Vessicchio Jennifer C. , Jones Karen M. , Vertrees Julia E. , Horney Rebecca A. , Huang Grant D. , Stock Christopher ,   for the Veterans Affairs Cooperative Study No. 504 Group
Published: August 2011

Context

Serotonin reuptake-inhibiting (SRI) antidepressants are the only FDA-approved pharmacotherapies for the treatment of posttraumatic stress disorder (PTSD).

Objective

To determine efficacy of the second-generation antipsychotic risperidone as an adjunct to ongoing pharmacologic and psychosocial treatments for veterans with chronic military-related PTSD.

Design, Setting, and Participants

A 6-month, randomized, double-blind, placebo-controlled multicenter trial conducted between February 2007 and February 2010 at 23 Veterans Administration outpatient medical centers. Of the 367 patients screened, 296 were diagnosed with military-related PTSD and had ongoing symptoms despite at least 2 adequate SRI treatments, and 247 contributed to analysis of the primary outcome measure.

Intervention

Risperidone (up to 4 mg once daily) or placebo.

Main Outcome Measures

The Clinician-Administered PTSD Scale (CAPS) (range, 0-136). Other measures included the Montgomery-Asberg Depression Rating Scale (MADRS), Hamilton Anxiety Scale (HAMA), Clinical Global Impression scale (CGI), and Veterans RAND 36-Item Health Survey (SF-36V).

Results

Change in CAPS scores from baseline to 24 weeks in the risperidone group was −16.3 (95% CI, −19.7 to −12.9) and in the placebo group, −12.5 (95% CI, −15.7 to −9.4); the mean difference was 3.74 (95% CI, −0.86 to 8.35; t = 1.6; P = .11). Mixed model analysis of all time points also showed no significant difference in CAPS score (risperidone: mean, 64.43; 95% CI, 61.98 to 66.89, vs placebo: mean, 67.16; 95% CI, 64.71 to 69.62; mean difference, 2.73; 95% CI, −0.74 to 6.20; P = .12). Risperidone did not reduce symptoms of depression (MADRS mean difference, 1.19; 95% CI, −0.29 to 2.68; P = .11) or anxiety (HAMA mean difference, 1.16; 95% CI, −0.18 to 2.51; P = .09; patient-rated CGI mean difference, 0.20; 95% CI, −0.06 to 0.45; P = .14; observer-rated CGI mean difference, 0.18; 95% CI, 0.01 to 0.34; P = .04), or increase quality of life (SF-36V physical component mean difference, −1.13, 95% CI, −2.58 to 0.32; P = .13; SF-36V mental component mean difference, −0.26; 95% CI, −2.13 to 1.61; P = .79). Adverse events were more common with risperidone vs placebo, including self-reported weight gain (15.3% vs 2.3%), fatigue (13.7% vs 0.0%), somnolence (9.9% vs 1.5%), and hypersalivation (9.9% vs 0.8%), respectively.

Conclusion

Among patients with military-related PTSD with SRI-resistant symptoms, 6-month treatment with risperidone compared with placebo did not reduce PTSD symptoms.

Trial Registration

clinicaltrials.gov Identifier: NCT00099983
Association between TCF4 and schizophrenia does not exert its effect by common nonsynonymous variation or by influencing cis‐acting regulation of mRNA expression in adult human brain
Authors: Williams Hywel J. , Moskvina Valentina , Smith Rhodri L. , Dwyer Sarah , Russo Giancarlo , Owen Michael J. , O'Donovan Michael C.
Published: August 2011

Large collaborative Genome‐wide Association studies of schizophrenia have identified genes and genomic regions that are associated with the disorder at highly stringent levels of statistical significance. Among these, transcription factor 4 (TCF4) is one of the best supported although the associated SNP (rs9960767) is located within intron 3 and has no obvious function. Seeking the mechanism at TCF responsible for the association, we examined TCF4 for coding variants, and for cis regulated variation in TCF4 gene expression correlated with the associated SNP using an assay to detect differential allelic expression. Using data from the 1000 genomes project, we were unable to identify any nonsynonymous coding variants at the locus. Allele specific expression analysis using human post mortem brain samples revealed no evidence for cis‐regulated mRNA expression related to genotype at the schizophrenia associated SNP. We conclude that association between schizophrenia and TCF4 is not mediated by a relatively common non‐synonymous variant, or by a variant that alters mRNA expression as measured in adult human brain. It remains possible that the risk allele at this locus exerts effects on expression exclusively in a developmental context, in cell types or brain regions not adequately represented in our analysis, or through post‐transcriptional effects, for example in the abundance of the protein or its sub‐cellular distribution. © 2011 Wiley‐Liss, Inc.
Genome scan of age‐at‐onset in the NIMH Alzheimer disease sample uncovers multiple loci, along with evidence of both genetic and sample heterogeneity
Authors: Choi Yoonha , Marchani Elizabeth E. , Bird Thomas D. , Steinbart Ellen J. , Blacker Deborah , Wijsman Ellen M.
Published: August 2011

Alzheimer's disease (AD) is a common neurodegenerative disorder of late life with a complex genetic basis. Although several genes are known to play a role in rare early onset AD, only theAPOEgene is known to have a high contribution to risk of the common late‐onset form of the disease (LOAD, onset >60 years).APOEgenotypes vary in their AD risk as well as age‐at‐onset distributions, and it is likely that other loci will similarly affect AD age‐at‐onset. Here we present the first analysis of age‐at‐onset in the NIMH LOAD sample that allows for both a multilocus trait model and genetic heterogeneity among the contributing sites, while at the same time accommodating age censoring, effects of known genetic covariates, and full pedigree and marker information. The results provide evidence for genomic regions not previously implicated in this data set, including regions on chromosomes 7q, 15, and 19p. They also affirm evidence for loci on chromosomes 1q, 6p, 9q, 11, and, of course, theAPOElocus on 19q, all of which have been reported previously in the same sample. The analyses failed to find evidence for linkage to chromosome 10 with inclusion of unaffected subjects and extended pedigrees. Several regions implicated in these analyses in the NIMH sample have been previously reported in genome scans of other AD samples. These results, therefore, provide independent confirmation of AD loci in family‐based samples on chromosomes 1q, 7q, 19p, and suggest that further efforts towards identifying the underlying causal loci are warranted. © 2011 Wiley‐Liss, Inc.
Distinct De Novo deletions in a brother–sister pair with RTT: A case report
Authors: Mittal Kirti , Gupta Neerja , Kabra Madhulika , Juyal Ramesh , Thelma B.K.
Published: August 2011

Rett syndrome (RTT), a neurodevelopmental disorder caused by mutations in the X‐linked gene encoding methyl‐CpG‐binding protein2 (MeCP2), is a leading cause of mental retardation in females. Majority of cases are sporadic (99%) but some familial cases have also been observed. We describe a familial study with a brother–sister pair with symptoms of RTT and exhibiting distinct deletions in the MECP2. The non‐shared de novo deletion in the two sibs provides important insights into the disease etiology, especially for male sibs showing varied phenotypes as compared to the classical ones seen in the females. © 2011 Wiley‐Liss, Inc.
High‐frequency oscillations as a new biomarker in epilepsy
Authors: Zijlmans Maeike , Jiruska Premysl , Zelmann Rina , Leijten Frans S.S. , Jefferys John G.R. , Gotman Jean
Published: August 2011

The discovery that electroencephalography (EEG) contains useful information at frequencies above the traditional 80Hz limit has had a profound impact on our understanding of brain function. In epilepsy, high‐frequency oscillations (HFOs, >80Hz) have proven particularly important and useful. This literature review describes the morphology, clinical meaning, and pathophysiology of epileptic HFOs. To record HFOs, the intracranial EEG needs to be sampled at least at 2,000Hz. The oscillatory events can be visualized by applying a high‐pass filter and increasing the time and amplitude scales, or EEG time‐frequency maps can show the amount of high‐frequency activity. HFOs appear excellent markers for the epileptogenic zone. In patients with focal epilepsy who can benefit from surgery, invasive EEG is often required to identify the epileptic cortex, but current information is sometimes inadequate. Removal of brain tissue generating HFOs has been related to better postsurgical outcome than removing the seizure onset zone, indicating that HFOs may mark cortex that needs to be removed to achieve seizure control. The pathophysiology of epileptic HFOs is challenging, probably involving populations of neurons firing asynchronously. They differ from physiological HFOs in not being paced by rhythmic inhibitory activity and in their possible origin from population spikes. Their link to the epileptogenic zone argues that their study will teach us much about the pathophysiology of epileptogenesis and ictogenesis. HFOs show promise for improving surgical outcome and accelerating intracranial EEG investigations. Their potential needs to be assessed by future research. Ann Neurol 2012;71:169–178
Systemic inflammation induces axon injury during brain inflammation
Authors: Moreno Beatriz , Jukes John‐Paul , Vergara‐Irigaray Nuria , Errea Oihana , Villoslada Pablo , Perry V. Hugh , Newman Tracey A.
Published: August 2011

Objective:

Axon injury is a key contributor to the progression of disability in multiple sclerosis (MS). Systemic infections, which frequently precede relapses in MS, have been linked to clinical progression in Alzheimer's disease. There is evidence of a role for the innate immune system in MS lesions, as axonal injury is associated with macrophage activation. We hypothesize that systemic inflammation leads to enhanced axonal damage in MS as a consequence of innate immune system activation.

Methods:

Monophasic experimental allergic encephalomyelitis (EAE) was induced in a cohort of Lewis rats. The animals received a systemic challenge with either an inflammagen (lipopolysaccharide [LPS]) or saline as a control, at 1, 3, or 6 weeks into the remission phase of the disease. The clinical outcome, cellular recruitment to lesions, degree of tissue damage, and cytokine profiles were measured.

Results:

We found that systemic inflammation activates the central nervous system (CNS) innate immune response and results in a switch in the macrophage/microglia phenotype. This switch was accompanied by inducible nitric oxide synthase (iNOS) and interleukin‐1β (IL‐1β) expression and increased axon injury. This increased injury occurred independently of the re‐emergence of overt clinical signs.

Interpretation:

Our evidence indicates that microglia/macrophages, associated with lesions, respond to circulating cytokines, produced in response to an inflammatory event outside the CNS, by producing immune mediators that lead to tissue damage. This has implications for people with MS, in which prevention and stringent management of systemic infectious diseases may slow disease progression. ANN NEUROL 2011;70:932–942
Tribological behavior of polyetheretherketone composites containing short carbon fibers and potassium titanate whiskers in dry sliding against steel
Authors: Ma N. , Lin G. M. , Xie G. Y. , Sui G. X. , Yang R.
Published: August 2011

Polyetheretherketone (PEEK) composites reinforced by short carbon fibers (SCF) and potassium titanate whiskers (PTW) were prepared using twin‐screw extrusion compounding and injection molding. The tribological properties of hybrid composites were investigated in dry sliding condition against steel. The effects of filler contents on the wear behavior were studied. It was found that the hybrid composite showed an excellent tribological property in dry sliding condition. Applied load had great effect on the tribological behavior of the composites. In most cases, the friction coefficient of the composite decreased with the load rising. The composites with higher CF contents showed outstanding tribological performances at low load but could worsen the wear behavior at high load. Because of the positive effect of PTW, high PTW loading composites presented low wear rate at low load. At high loads, the composites with lower PTW contents had better wear resistance. The scanning electron microscopy (SEM) observation revealed that abrasion wear was attributed to the lower wear resistance of the high PTW content composite at high load. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation of chitosan‐coated magnetite nanoparticles and application for immobilization of laccase
Authors: Kalkan Nuzhet Ayca , Aksoy Serpil , Aksoy Eda Ayse , Hasirci Nesrin
Published: August 2011

In this study, immobilization of laccase (L) enzyme on magnetite (Fe3O4) nanoparticles was achieved, so that the immobilized enzyme could be used repeatedly. For this purpose, Fe3O4 nanoparticles were coated and functionalized with chitosan (CS) and laccase from Trametes versicolor was immobilized onto chitosan‐coated magnetic nanoparticles (Fe3O4‐CS) by adsorption or covalent binding after activating the hydroxyl groups of chitosan with carbodiimide (EDAC) or cyanuric chloride (CC). For chitosan‐coated magnetic nanoparticles, the thickness of CS layer was estimated as 1.0–4.8 nm by TEM, isoelectric point was detected as 6.86 by zeta (ζ)‐potential measurements, and the saturation magnetization was determined as 25.2 emu g−1 by VSM, indicating that these nanoparticles were almost superparamagnetic. For free laccase and immobilized laccase systems, the optimum pH, temperature, and kinetic parameters were investigated; and the change of the activity against repeated use of the immobilized systems were examined. The results indicated that all immobilized systems retained more than 71% of their initial activity at the end of 30 batch uses. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Impaired dendritic cell proinflammatory cytokine production in psoriatic arthritis
Authors: Wenink Mark H. , Santegoets Kim C. M. , Butcher John , van Bon Lenny , Lamers‐Karnebeek Femke G. M. , van den Berg Wim B. , van Riel Piet L. C. M. , McInnes Iain B. , Radstake Timothy R. D. J.
Published: August 2011

Objective

The pathogenesis of psoriatic arthritis (PsA) remains poorly understood. The underlying chronic inflammatory immune response is thought to be triggered by unknown environmental factors potentially arising from a defective immune function. We undertook this study to determine whether an impaired acute inflammatory response by dendritic cells (DCs) might compromise the clearance of bacteria and predispose to chronic inflammation.

Methods

We determined cytokine production by DCs from healthy controls and from patients with rheumatoid arthritis, PsA, and psoriasis in response to Mycobacterium tuberculosis, Mycobacterium avium paratuberculosis, and a range of other bacteria and Toll‐like receptor (TLR) ligands. Phenotypic differences involved in cellular responses against (myco)bacteria were determined by quantitative polymerase chain reaction and flow cytometry.

Results

The secretion of proinflammatory cytokines by PsA DCs was impaired upon in vitro challenge with mycobacteria and TLR‐2 ligands. This impairment was associated with elevated serum levels of C‐reactive protein. The expression of TLR‐2 and other receptors known to mediate mycobacterial recognition was unaltered. In contrast, the intracellular TLR inhibitors suppressor of cytokine signaling 3 and A20 were more highly expressed in DCs from PsA patients. PsA DCs further demonstrated up‐regulated levels of ATG16L1, NADPH oxidase 2, and LL37, which are molecules implicated in the immune response against intracellular bacteria.

Conclusion

Our findings indicate that DCs from PsA patients have a disordered immune response toward some species of (myco)bacteria. This might predispose to impaired immune responses to, and in turn impaired clearance of, these bacteria, setting the stage for the chronic inflammation of joints, entheses, skin, and the gut.
Biodiversität und Klima: Wandel in vollem Gange!
Authors: Streit Bruno , Böhning‐Gaese Katrin , Mosbrugger Volker
Published: August 2011

Der globale Wandel ist in vollem Gange und betrifft nicht nur das Klima, sondern auch die Biodiversität. Gleichzeitig führen weltweite Änderungen in der Land‐ und Wassernutzung sowie invasive Arten zu rasanten Veränderungen unserer Lebensgemeinschaften. Die Menschheit ist auf vielfältige Weise von diesem Wandel betroffen. Globaler Wandel wird in vielen Ländern zu steigender Armut und politischen Unruhen führen. Die Erforschung der Ursachen und Folgen von Biodiversitäts‐ und Klimaveränderungen und ihre Diskussion in der Gesellschaft stellen eine zentrale Herausforderung dar.
Brieftauben
Authors: Mehlhorn Julia , Rehkämper Gerd
Published: August 2011

Das hervorragende Heimfindevermögen von Brieftauben beschäftigt sowohl Wissenschaftler als auch Züchter, die ihre Tiere an Wettflügen teilnehmen lassen. Brieftauben ziehen unter anderem einen Sonnenkompass, das Erdmagnetfeld, Landmarken und Geruchsinformationen zur Heimfindung heran. Auch spielen Erfahrung und Motivation eine große Rolle. Durch die intensive Selektion durch den Menschen hat sich die Brieftaube zu einem Tier entwickelt, welches optimal in seinen Gehirn‐ und Flugleistungen an das Absolvieren unbekannter Strecken angepasst ist. Dies wird vor allem bei den noch heute zahlreich stattfindenden Wettflügen deutlich, bei denen die Tiere zu Höchstleistungen gebracht werden.
Das Weltnaturerbe Wattenmeer in Deutschland ist komplett
Authors: Janke Klaus
Published: August 2011

In seiner jüngsten Sitzung in Paris hat das UNESCO‐Welterbe‐Komitee am 27.06.2011 beschlossen, den Nationalpark Hamburgisches Wattenmeer als Teil des Weltnaturerbes Wattenmeer in die Liste der Welterbestätten der Menschheit einzuschreiben. Damit holt Hamburg seine mit den Niederlanden, Niedersachsen und Schleswig‐Holstein ursprünglich gemeinsam beschlossene Anmeldung nach. Der Nationalpark ist jetzt ein anerkanntes Schutzgebiet von Weltrang und komplettiert zugleich den deutschen Anteil des grenzüberschreitenden Welterbegebietes.
RNA‐Editing in Pflanzen: dem Editor auf der Spur
Authors: Knoop Volker
Published: August 2011

Vor 20 Jahren wurde RNA‐Editing in Pflanzen entdeckt: Darunter versteht man den gezielten Austausch von Cytidinen zu Uridinen an spezifischen Positionen in den RNAs der Mitochondrien und Chloroplasten. Wie extrem RNA‐Editing in Pflanzen werden kann, zeigen jetzt die mitochondrialen Genome von Bärlappgewächsen mit tausenden solcher Editing‐Stellen. Das Laubmoos Physcomitrella patens hingegen ist besonders arm an RNA‐Editing und damit ein ausgezeichneter Modellorganismus, um den zugrundeliegenden Mechanismen auf die Spur zu kommen.
Molekulare Uhr ohne Gene
Authors: Brennicke Axel
Published: August 2011

Bei Bakterien, Pflanzen und Tieren ticken innere Uhren in einem Räderwerk von Genen und Proteinen. Da bei diesen Organismen völlig unterschiedliche Moleküle beteiligt sind, ist man bisher von parallelen, unabhängigen Evolutionswegen ausgegangen. Jetzt wurden nicht nur in photosynthetischen Einzellern, sondern auch in den roten Blutkörperchen von Menschen neue Uhren gefunden, die auf reiner Proteinbasis funktionieren. Noch ist nicht ganz klar, ob dies echte Uhrwerke sind oder ob sie Zeiger einer neuen Uhr sind und als Sensoren auf die unterschiedlichen Temperaturen von Tag und Nacht reagieren.