268 research outputs found
Diffusion Tensor Imaging in Joubert Syndrome
BACKGROUND AND PURPOSE: Neuropathologic findings and preliminary imaging studies demonstrated the absence of pyramidal tract and superior cerebellar peduncular decussation in individual patients with Joubert syndrome (JS). We hypothesized that functional-structural neuroimaging findings do not differ between the genetic forms of JS. MATERIALS AND METHODS: MR imaging was performed with a 3T MR imaging-unit. Multiplanar T2- and T1-weighted imaging was followed by diffusion tensor imaging (DTI). Isotropic diffusion-weighted images, apparent diffusion coefficient maps, and color-coded fractional anisotropy maps, including tractography, were subsequently calculated. RESULTS: In all 6 patients studied, DTI showed that the fibers of the superior cerebellar peduncles did not decussate in the mesencephalon and the corticospinal tract failed to cross in the caudal medulla. The patients represented various genetic forms of JS. CONCLUSION: In JS, the fibers of the pyramidal tract and the superior cerebellar peduncles do not cross, irrespective of the underlying mutation
Extremism propagation in social networks with hubs
One aspect of opinion change that has been of academic interest is the impact of people with extreme opinions (extremists) on opinion dynamics. An agent-based model has been used to study the role of small-world social network topologies on general opinion change in the presence of extremists. It has been found that opinion convergence to a single extreme occurs only when the average number of network connections for each individual is extremely high. Here, we extend the model to examine the effect of positively skewed degree distributions, in addition to small-world structures, on the types of opinion convergence that occur in the presence of extremists. We also examine what happens when extremist opinions are located on the well-connected nodes (hubs) created by the positively skewed distribution. We find that a positively skewed network topology encourages opinion convergence on a single extreme under a wider range of conditions than topologies whose degree distributions were not skewed. The importance of social position for social influence is highlighted by the result that, when positive extremists are placed on hubs, all population convergence is to the positive extreme even when there are twice as many negative extremists. Thus, our results have shown the importance of considering a positively skewed degree distribution, and in particular network hubs and social position, when examining extremist transmission
Studying Paths of Participation in Viral Diffusion Process
Authors propose a conceptual model of participation in viral diffusion
process composed of four stages: awareness, infection, engagement and action.
To verify the model it has been applied and studied in the virtual social chat
environment settings. The study investigates the behavioral paths of actions
that reflect the stages of participation in the diffusion and presents
shortcuts, that lead to the final action, i.e. the attendance in a virtual
event. The results show that the participation in each stage of the process
increases the probability of reaching the final action. Nevertheless, the
majority of users involved in the virtual event did not go through each stage
of the process but followed the shortcuts. That suggests that the viral
diffusion process is not necessarily a linear sequence of human actions but
rather a dynamic system.Comment: In proceedings of the 4th International Conference on Social
Informatics, SocInfo 201
Dalitz plot analysis of e+ e- --> pi0 pi0 gamma events at SQRT(s) ~ M(phi) with the KLOE detector
We have studied the Dalitz plot of the e+ e- --> pi0 pi0 gamma events
collected at SQRT(s) ~ M(phi) with the KLOE detector. In the dipion invariant
mass (Mpp) region below 700 MeV, the process under study is dominated by the
non-resonant process e+ e- --> omega pi0 with omega --> pi0 gamma whereas, for
higher Mpp values, the radiative phi decay to the f0(980) is the dominant
mechanism. Different theoretical models are used to fit the Dalitz plot, taking
also into account a possible contribution of the sigma(600). For each model, we
extract the f0(980) mass and its coupling to pipi, KKbar and to the phi.Comment: 21 pages, 15 figures, 5 tables, submitted to European Physics Journal
SUFU haploinsufficiency causes a recognisable neurodevelopmental phenotype at the mild end of the Joubert syndrome spectrum.
Joubert syndrome (JS) is a recessively inherited ciliopathy characterised by congenital ocular motor apraxia (COMA), developmental delay (DD), intellectual disability, ataxia, multiorgan involvement, and a unique cerebellar and brainstem malformation. Over 40 JS-associated genes are known with a diagnostic yield of 60%-75%.In 2018, we reported homozygous hypomorphic missense variants of the SUFU gene in two families with mild JS. Recently, heterozygous truncating SUFU variants were identified in families with dominantly inherited COMA, occasionally associated with mild DD and subtle cerebellar anomalies.
We reanalysed next generation sequencing (NGS) data in two cohorts comprising 1097 probands referred for genetic testing of JS genes.
Heterozygous truncating and splice-site SUFU variants were detected in 22 patients from 17 families (1.5%) with strong male prevalence (86%), and in 8 asymptomatic parents. Patients presented with COMA, hypotonia, ataxia and mild DD, and only a third manifested intellectual disability of variable severity. Brain MRI showed consistent findings characterised by vermis hypoplasia, superior cerebellar dysplasia and subtle-to-mild abnormalities of the superior cerebellar peduncles. The same pattern was observed in two out of three tested asymptomatic parents.
Heterozygous truncating or splice-site SUFU variants cause a novel neurodevelopmental syndrome encompassing COMA and mild JS, which likely represent overlapping entities. Variants can arise de novo or be inherited from a healthy parent, representing the first cause of JS with dominant inheritance and reduced penetrance. Awareness of this condition will increase the diagnostic yield of JS genetic testing, and allow appropriate counselling about prognosis, medical monitoring and recurrence risk
Modelagem das trajetórias médias do peso vivo e do rendimento de carcaça de tilápias do Nilo (Oreochromis niloticus) por meio de funções B-spline
Bacterial cellulose and bacterial cellulose/polycaprolactone composite as tissue substitutes in rabbits' cornea
Genome-wide association and Meta-analysis of age at onset in Parkinson Disease
Background and Objectives Considerable heterogeneity exists in the literature concerning genetic determinants of the age at onset (AAO) of Parkinson disease (PD), which could be attributed to a lack of well-powered replication cohorts. The previous largest genome-wide association studies (GWAS) identified SNCA and TMEM175 loci on chromosome (Chr) 4 with a significant influence on the AAO of PD; these have not been independently replicated. This study aims to conduct a meta-analysis of GWAS of PD AAO and validate previously observed findings in worldwide populations.
Methods A meta-analysis was performed on PD AAO GWAS of 30 populations of predominantly European ancestry from the Comprehensive Unbiased Risk Factor Assessment for Genetics and Environment in Parkinson's Disease (COURAGE-PD) Consortium. This was followed by combining our study with the largest publicly available European ancestry dataset compiled by the International Parkinson Disease Genomics Consortium (IPDGC).
Results The COURAGE-PD Consortium included a cohort of 8,535 patients with PD (91.9%: Europeans and 9.1%: East Asians). The average AAO in the COURAGE-PD dataset was 58.9 years (SD = 11.6), with an underrepresentation of females (40.2%). The heritability estimate for AAO in COURAGE-PD was 0.083 (SE = 0.057). None of the loci reached genome-wide significance (p < 5 × 10−8). Nevertheless, the COURAGE-PD dataset confirmed the role of the previously published TMEM175 variant as a genetic determinant of the AAO of PD with Bonferroni-corrected nominal levels of significance (p < 0.025): (rs34311866: β(SE)COURAGE = 0.477(0.203), pCOURAGE = 0.0185). The subsequent meta-analysis of COURAGE-PD and IPDGC datasets (Ntotal = 25,950) led to the identification of 2 genome-wide significant association signals on Chr 4, including the previously reported SNCA locus (rs983361: β(SE)COURAGE+IPDGC = 0.720(0.122), pCOURAGE+IPDGC = 3.13 × 10−9) and a novel BST1 locus (rs4698412: β(SE)COURAGE+IPDGC = −0.526(0.096), pCOURAGE+IPDGC = 4.41 × 10−8).
Discussion Our study further refines the genetic architecture of Chr 4 underlying the AAO of the PD phenotype through the identification of BST1 as a novel AAO PD locus. These findings open a new direction for the development of treatments to delay the onset of PD
Processos condicionantes de alterações em variáveis limnológicas: uma abordagem estatística na Represa de São Pedro, Juiz de Fora (MG)
RESUMO Os mananciais de abastecimento de água são ativos ambientais que precisam da atenção de toda a sociedade. O monitoramento de variáveis limnológicas possibilita inferir sobre as condições do recurso hídrico, além de oferecer indicativos de toda a dinâmica natural ou antrópica compreendida na bacia hidrográfica. A precipitação é um dos principais mecanismos atuantes nos parâmetros de qualidade de água, o que justifica sua relevância nesse tipo de análise. O teste t de Student e a análise fatorial/análise de componentes principais constituíram importantes ferramentas na interpretação dos dados limnológicos da captação da Represa de São Pedro, Juiz de Fora, Minas Gerais. O teste t de Student possibilitou verificar quais parâmetros apresentaram variação sazonal estatisticamente significativa. Já os resultados da análise fatorial/análise de componentes principais apontaram as variáveis mais relevantes na qualidade da água do manancial. A análise conjunta dos resultados estatísticos definiu os processos condicionantes das alterações nas variáveis estudadas, indicando o escoamento superficial como principal determinante das variáveis que compõem as componentes após rotação da matriz de componentes principais, Fator Varimax FV1 e FV4, e a contribuição orgânica, não associada à precipitação, como reflexo das variáveis da FV2 e FV3
Características agronômicas de cultivares de milho (Zea mays L.) e qualidade dos componentes e silagem
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