A Bayesian Heteroscedastic GLM with Application to fMRI Data with Motion Spikes

We propose a voxel-wise general linear model with autoregressive noise and heteroscedastic noise innovations (GLMH) for analyzing functional magnetic resonance imaging (fMRI) data. The model is analyzed from a Bayesian perspective and has the benefit of automatically down-weighting time points close to motion spikes in a data-driven manner. We develop a highly efficient Markov Chain Monte Carlo (MCMC) algorithm that allows for Bayesian variable selection among the regressors to model both the mean (i.e., the design matrix) and variance. This makes it possible to include a broad range of explanatory variables in both the mean and variance (e.g., time trends, activation stimuli, head motion parameters and their temporal derivatives), and to compute the posterior probability of inclusion from the MCMC output. Variable selection is also applied to the lags in the autoregressive noise process, making it possible to infer the lag order from the data simultaneously with all other model parameters. We use both simulated data and real fMRI data from OpenfMRI to illustrate the importance of proper modeling of heteroscedasticity in fMRI data analysis. Our results show that the GLMH tends to detect more brain activity, compared to its homoscedastic counterpart, by allowing the variance to change over time depending on the degree of head motion

Factor Structure and Construct Validity of the Worker Role Self-Assessment (WRS) When Used for People With Psychiatric Disabilities in Sweden

A self-report instrument assessing work-related factors among people with psychiatric disabilities would be useful when trying to match possible employment or prevocational opportunities with people’s desires and capacities. The aim of this study was to explore the factor structure, internal consistency, and construct and criterion validity of the Worker Role Self-Assessment (WRS) in this group as well as possible floor and ceiling effects. The participants were 283 clients from day centers for people with psychiatric disabilities and from outpatient units for people with psychosis. They completed the WRS and instruments selected to assess construct validity in terms of convergent (motivation for work and current activity level as reference variables) and discriminant validity (quality of life and self-rated health as reference variables). Two factors were identified, one tapping beliefs in a future worker role and one reflecting current capacities and routines. The internal consistency for the scale as a whole was good at 0.84. The factor reflecting a future worker role correlated as expected with the reference variables used to assess convergent and discriminant validity, whereas current capacities and routines showed a moderate association with quality of life and self-rated health, assumed to indicate discriminant validity. Criterion validity was shown in that those who had recent work experiences scored higher than the others on WRS. No floor or ceiling effects were identified. The findings indicate acceptable psychometric properties of the WRS. Further development is still warranted, however; the factor solution needs to be replicated and the construct validity should be further established

Studying the ability to use sport watches when running - insights from a small pilot study

Digitalization is a phenomenon that seems to affect all aspects of contemporary society. The sports domain is by no means excluded from this development. In sports, the sport watch might be one of the most iconic symbols in how digitalization has enhanced, changed and developed how physical activities are experienced and measured. Despite the massive adoption of sport watches among runners and other athletes, few studies have explored how sports watches are used in the specific activity they are designed for. The study presented in this research in progress paper is small and should be viewed as a small attempt to outline an approach to study digital technology use in sports activities

Data and methods in the environment-migration nexus: a scale perspective

The relationship between environment and migration has gained increased attention since the 1990s when the Intergovernmental Panel on Climate Change projected climate change to become a major driver of ­human migration. Evaluations of this relationship include both quantitative and qualitative assessments. This review article introduces the concept of scale to environment-migration research as an important methodological issue for the reliability of conclusions drawn. The review of case studies shows that scale issues are highly present in environment-migration research but rarely discussed. Several case studies base their results on data at very coarse resolutions that have undergone strong modifications and generalizations. We argue that scale-related shortcomings must be considered in all stages of environment-migration research

The Relationships Among Competitiveness, Age and Ability In Distance Runners

The purpose of this study was to examine relationships suggested by general achievement motivation literature and the popular literature in sport using the Sport Orientation Questionnaire (SOQ). The current study examined if faster runners are more competitive than slower runners, if older athletes were less competitive than younger athletes, and if faster runners were more goal oriented than slower runners. Distance runners (n=80), ranging from 10 to 61 years old completed race packets containing a cover letter, consent forms, the SOQ and a demographic questionnaire. Runners averaged 32.9 years of age and reported levels of competitiveness and goal orientation consistent with previous research. Results indicated that competitiveness and age were negatively related (r = -.44, p \u3c 001) and competitiveness and personal best times for all race distances were positively associated (r = .28, p \u3c .05 to .33, p \u3c .01). Ability and goal orientation were unrelated. In conclusion, both ability and age, in addition to a variety of significant social and cognitive correlates, may contribute to the development and decline of competitiveness. Future research should examine the way that competitiveness and related cognitions develop and wane over the life span

Factor Structure of the Athletic Identity Measurement Scale With Athletes With Disabilities

Individuals who perceive themselves as athletes are thought to have self-schemas composed of, in part, an athletic identity (Brewer, Van Raalte, & Linder, 1993). The recent development of the Athletic Identity Measurement Scale (AIMS) has allowed sport psychology researchers to assess athletic identity. Research with adolescent athletes with disabilities has suggested that the AIMS is composed of 4 factors (Martin, Mushett, & Eklund, 1994). The purpose of the current study was to further examine the psychometric properties of the AIMS. Seventy-eight international swimmers (34 females, 44 males) with disabilities, ranging in age from 12 to 44 (M = 23.4 years), participated in the present study. Using structural equation modeling procedures, a confirmatory factor analysis determined that the data fit the 4-factor model specified in the Martin et al. (1994) study, thus providing support for the multidimensionality of the AIMS

Using Crop Phenology to Assess Changes in Cultivated Land after the Anfal Genocide in Iraqi Kurdistan

Ponencias, comunicaciones y pósters presentados en el 17th AGILE Conference on Geographic Information Science "Connecting a Digital Europe through Location and Place", celebrado en la Universitat Jaume I del 3 al 6 de junio de 2014.The Anfal genocide campaign, carried out by the Iraqi government against the Kurdish population in 1988, has been reported to have severe consequences for agriculture and food security by causing large scale land abandonment. This study uses Landsat satellite data to detect agricultural changes that can be attributed to the Anfal genocide. Cultivated land were distinguished from other land cover types by focusing on crop phenology. Initial results show a strong decrease in cultivated land in the years after the genocide, especially in the areas that were targeted by the genocide campaign

Proteochemometric modeling of HIV protease susceptibility

<p>Abstract</p> <p>Background</p> <p>A major obstacle in treatment of HIV is the ability of the virus to mutate rapidly into drug-resistant variants. A method for predicting the susceptibility of mutated HIV strains to antiviral agents would provide substantial clinical benefit as well as facilitate the development of new candidate drugs. Therefore, we used proteochemometrics to model the susceptibility of HIV to protease inhibitors in current use, utilizing descriptions of the physico-chemical properties of mutated HIV proteases and 3D structural property descriptions for the protease inhibitors. The descriptions were correlated to the susceptibility data of 828 unique HIV protease variants for seven protease inhibitors in current use; the data set comprised 4792 protease-inhibitor combinations.</p> <p>Results</p> <p>The model provided excellent predictability (<it>R</it>²= 0.92, <it>Q</it>²= 0.87) and identified general and specific features of drug resistance. The model's predictive ability was verified by external prediction in which the susceptibilities to each one of the seven inhibitors were omitted from the data set, one inhibitor at a time, and the data for the six remaining compounds were used to create new models. This analysis showed that the over all predictive ability for the omitted inhibitors was <it>Q</it>²_{<it>inhibitors </it>}= 0.72.</p> <p>Conclusion</p> <p>Our results show that a proteochemometric approach can provide generalized susceptibility predictions for new inhibitors. Our proteochemometric model can directly analyze inhibitor-protease interactions and facilitate treatment selection based on viral genotype. The model is available for public use, and is located at HIV Drug Research Centre.</p

The electronic-structure origin of the anisotropic thermopower of nanolaminated Ti3SiC2 determined by polarized x-ray spectroscopy and Seebeck measurements

Nanolaminated materials exhibit characteristic magnetic, mechanical, and thermoelectric properties, with large contemporary scientific and technological interest. Here, we report on the anisotropic Seebeck coefficient in nanolaminated Ti3SiC2 single-crystal thin films and trace the origin to anisotropies in element-specific electronic states. In bulk polycrystalline form, Ti3SiC2 has a virtually zero Seebeck coefficient over a wide temperature range. In contrast, we find that the in-plane (basal ab) Seebeck coefficient of Ti3SiC2, measured on single-crystal films has a substantial and positive value of 4-6 muV/K. Employing a combination of polarized angle-dependent x-ray spectroscopy and density functional theory we directly show electronic structure anisotropy in inherently nanolaminated Ti3SiC2 single-crystal thin films as a model system. The density of Ti 3d and C 2p states at the Fermi level in the basal ab-plane is about 40 % higher than along the c-axis. The Seebeck coefficient is related to electron and hole-like bands close to the Fermi level but in contrast to ground state density functional theory modeling, the electronic structure is also influenced by phonons that need to be taken into account. Positive contribution to the Seebeck coefficient of the element-specific electronic occupations in the basal plane is compensated by 73 % enhanced Si 3d electronic states across the laminate plane that give rise to a negative Seebeck coefficient in that direction. Strong phonon vibration modes with three to four times higher frequency along the c-axis than along the basal ab-plane also influence the electronic population and the measured spectra by the asymmetric average displacements of the Si atoms. These results constitute experimental evidence explaining why the average Seebeck coefficient of Ti3SiC2 in polycrystals is negligible over a wide temperature range.Comment: 13 pages, 6 figures; http://prb.aps.org/abstract/PRB/v85/i19/e19513