We investigated the differences in brain fMRI signal complexity in patients with schizophrenia while performing the Cyberball social exclusion task, using measures of Sample entropy and Hurst exponent (H). 13 patients meeting diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM IV) criteria for schizophrenia and 16 healthy controls underwent fMRI scanning at 1.5 T. The fMRI data of both groups of participants were pre-processed, the entropy characterized and the Hurst exponent extracted. Whole brain entropy and H maps of the groups were generated and analysed. The results after adjusting for age and sex differences together show that patients with schizophrenia exhibited higher complexity than healthy controls, at mean whole brain and regional levels. Also, both Sample entropy and Hurst exponent agree that patients with schizophrenia have more complex fMRI signals than healthy controls. These results suggest that schizophrenia is associated with more complex signal patterns when compared to healthy controls, supporting the increase in complexity hypothesis, where system complexity increases with age or disease, and also consistent with the notion that schizophrenia is characterised by a dysregulation of the nonlinear dynamics of underlying neuronal systems.
Summary. The volumes and spin‐lattice (T1) relaxation times of breast tissues and parenchymal water content were measured non‐invasively by magnetic resonance imaging (MRI) in eight healthy women during four to eight consecutive menstrual cycles. Total breast volume, and parenchymal volume, T1 relaxation time and water content were lowest between days 6 and 15. Between days 16 and 28, parenchymal volume, T1 relaxation time and water content rose sharply by 38·9%, 15·1% and 24·5%, respectively, and peaked after day 25. Within 5 days of the onset of menses, parenchymal volume fell sharply by 30·3%, while water content declined by 17·5%. Rising parenchymal volume in the second half of the menstrual cycle is not solely due to increased tissue water content and provides in vivo evidence for both growth and increased tissue fluid at this time.
Total and subcutaneous adipose tissue in seven lean and seven obese women were quantified using magnetic resonance imaging (MRI). The distributions of adipose tissues along the body were closely correlated: subcutaneous with total, both within and between lean and obese groups. Lean women had proportionally less adipose tissue in the lower thorax and upper abdomen than did obese women. Reducing the number of MRI scans from 17 to 4 did not increase the residual SD of predicted body adipose tissue (2.9 percent) when body density was used as the reference measure. MRI gave an estimate of total-body adipose tissue significantly closer to the value for fat percent produced when the results from five other techniques (skinfold thickness, underwater weighing, 40K whole-body counting, isotopic water dilution, and tetrapolar bioelectrical impedance) were averaged than when any other technique was used alone. MRI-determined percent body adipose tissue in women is close to, and proportional to, estimates derived by underwater weighing.
Conductivities and viscosities of solutions of Li, Na and K thiocyanates in low-molecular-weight liquid copolymers of ethylene oxide and propylene oxide have been measured. The curves of molar conductance us. c5 show well defined maxima and minima. The conductivity is independent of copolymer molecular weight but is enhanced by raising the EO content of the copolymer. The results are interpreted in terms of a model in which the effects of ion association and re-dissociation play an important role. It is suggested that the characteristic properties of liquid polymer electrolytes can be satisfactorily explained only if the current is largely anionic.
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