Twist in a Torus: Minimization of Nematic Configurations with Discontinuous Director Fields in Toroidal Coordinates

The ring disclination is a topological defect that may be suitable for light polarization inside of a nematic liquid crystal. Due to its stability and chirality, the ring disclination could also allow for theoretical applications to quantum and classical field theories as a model for fundamental particles. In order to model this defect within a nematic liquid crystal, we simulate a director field outside of a torus boundary. Equations are derived for the energy density of this configuration. Toroidal coordinates are implemented as a mesh on which the configuration is defined so that calculations remain stable for small tori. Deterministic iterative methods are developed for calculating the minimum energy of the system. Proof of the vector Laplacian as the correct minimization operator for generalized orthogonal coordinates is demonstrated using differential forms and Lagrange multipliers. The vector Laplacian is derived in toroidal coordinates and implemented in a hybrid regime with minimization of regions far from the torus surface occurring in Cartesian coordinates. This is implemented with mixed results. The minimized energy scales linearly with torus size as expected by dimensional analysis, but challenges remain for energy minimization at small sizes of torus. Possible solutions for extending the domain are discussed.Key Words: Topological Defect, Nematic Liquid Crystal, Toroidal Coordinate

The influence of Schizotypy on Event Related Oscillations in Sensory Gating during early Infant Development

Maternal personality is known to influence childhood risk factors for mental health. More specifically, maternal psychopathologies, such as those on the schizophrenia-spectrum have been associated with P50 sensory gating abilities. Schizotypy is a personality dimension within the general population elevated among schizophrenia-spectrum patients and their first-degree relatives. Sensory gating is the pre-attentional habituation of responses distinguishing between important and irrelevant information. Neurooscillatory deficits have been observed in this ability in individuals diagnosed with schizophrenia. The current study investigated whether mothers with schizotypy (n=33) and their 6-month-old infants (n=38) display reduced evoked-oscillatory activity. The mothers completed the Oxford-Liverpool Inventory of Feelings and Experiences – Short Form as an index of schizotypy dimensionality, which was used to categorise the participants into infants of control mothers and mothers with schizotypy. The paired-tone paradigm: two identical auditory tones (Stimulus 1 and Stimulus 2) played 500ms apart, were used to probe evoked oscillatory activity. Data revealed that although the infants’ evoked-oscillations displayed differences between Stimulus 1 and Stimulus 2, there were no group differences between infants of mothers with schizotypy and of control mothers. Their mothers, however, displayed differences, with reduced power toward Stimulus 1 observed in the mothers with schizotypy between 13-30Hz. These findings are consistent that early sensory processes, such as sensory gating are impaired in schizophrenia-spectrum disorders

The Influence of Maternal Schizotypy on the perception of Facial Emotional Expressions during Infancy:an Event-Related Potential Study

Parenting directly affects the developmental and clinical outcomes of children. How parental personality relates to perceptual and cognitive mechanisms during early development is not clear. For parents with traits of the personality dimension schizotypy, would their infant display brain responses similar to those on the schizophrenia-spectrum? This study investigates whether maternal personality influences early social-cognitive awareness during the first 6 postnatal months. Schizotypy is a dimension of personality within the general population. If deficits contribute to the development of schizophrenia-spectrum disorders by influencing the development of symptom-like characteristics, they may be observable in neurotypical individuals with schizotypal characteristics. Parents and their infants were shown standardised positive and negative faces and event-related potential responses were assessed. It was hypothesised that the infants of schizotypic mothers would display differential Negative-central event-related potentials for the happy and fearful expressions when compared to infants of non-schizotypic mothers. Results support prior literature; indicating 6-month-old infants allocate more attentional resources to fearful when contrasted to happy faces. The adult cohort displays this same ability. In addition, schizotypic mothers displayed comparable amplitudes for both expressions in comparison to the control mothers who exhibited larger amplitudes towards the fearful compared to the happy expression. Infants of schizotypic mothers did not show a greater sensitivity to facial expressions at 6-months, but schizotypic mothers showed a generalised response towards facial expressions compared to the typical P600 response illustrated by the control mothers. The present study suggests that development in the higher cognitive domains, such as the allocation of attention to novel stimuli, are not affected at 6 months of age by maternal personality related to schizotypy when examined at the group level. Implications for personality development, maternal-infant interactions and cognitive neuroscience methodologies are discussed

Why general education?: Peters, Hirst and history

Richard Peters argued for a general education based largely on the study of truth-seeking subjects for its own sake. His arguments have long been acknowledged as problematic. There are also difficulties with Paul Hirst's arguments for a liberal education, which in part overlap with Peters'. Where justification fails, can historical explanation illuminate? Peters was influenced by the prevailing idea that a secondary education should be based on traditional, largely knowledge-orientated subjects, pursued for intrinsic as well as practical ends. Does history reveal good reasons for this view? The view itself has roots going back to the 16th century and the educational tradition of radical Protestantism. Religious arguments to do with restoring the image of an omniscient God in man made good sense, within their own terms, of an encyclopaedic approach to education. As these faded in prominence after 1800, old curricular patterns persisted in the drive for ‘middle-class schools’, and new, less plausible justifications grew in salience. These were based first on faculty psychology and later on the psychology of individual differences. The essay relates the views of Peters and Hirst to these historical arguments, asking how far their writings show traces of the religious argument mentioned, and how their views on education and the development of mind relate to the psychological arguments

Is schizotypic maternal personality linked to sensory gating abilities during infancy?

Schizotypy is a personality dimension within the general population elevated among schizophrenia-spectrum patients and their first-degree relatives. Sensory gating is the pre-attentional habituation of responses distinguishing between important and irrelevant information. This is measured by event-related potentials, which have been found to display abnormalities in schizophrenic disorders. The current study investigated whether 6-month-old infants of mothers with schizotypic traits display sensory gating abnormalities. The paired-tone paradigm: two identical auditory tones (stimulus 1 and stimulus 2) played 500 ms apart, was used to probe the selective activation of the brain during 15-minutes of sleep. Their mothers completed the Oxford and Liverpool Inventory of Feelings and Experiences-Short Form as an index of schizotypy dimensionality, categorized into: infants of control, and infants of schizotypic, mothers. The findings revealed that although the infants' P50 components displayed significant differences between stimulus 1 and stimulus 2 in the paired-tone paradigm, there was no clear difference between infants of schizotypic and infants of control mothers. In contrast, all mothers displayed significant differences between stimulus 1 and stimulus 2, as observed in the infants, but also significant differences between their sensory gating ability correlated with schizotypy dimensionality. These findings are consistent with sensory processes, such as sensory gating, evidencing impairment in schizophrenia-spectrum disorders. The present research supports the idea that first-degree relatives of individuals who identify on this spectrum, within the sub-clinical category, do not display the same deficit at 6 postnatal months of age

Prevalence of prehypertension and its relationship to risk factors for cardiovascular disease in Jamaica: Analysis from a cross-sectional survey

<p>Abstract</p> <p>Background</p> <p>Recent studies have documented an increased risk of cardiovascular disease (CVD) in persons with systolic blood pressures of 120–139 mmHg and/or diastolic blood pressures of 80–89 mmHg, classified as prehypertension in the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. In this paper we estimate the prevalence of prehypertension in Jamaica and evaluate the relationship between prehypertension and other risk factors for CVD.</p> <p>Methods</p> <p>The study used data from participants in the Jamaica Lifestyle Survey conducted from 2000–2001. A sample of 2012 persons, 15–74 years old, completed an interviewer administered questionnaire and had anthropometric and blood pressure measurements performed by trained observers using standardized procedures. Fasting glucose and total cholesterol were measured using a capillary blood sample. Analysis yielded crude, and sex-specific prevalence estimates for prehypertension and other CVD risk factors. Odds ratios for associations of prehypertension with CVD risk factors were obtained using logistic regression.</p> <p>Results</p> <p>The prevalence of prehypertension among Jamaicans was 30% (95% confidence interval [CI] 27%–33%). Prehypertension was more common in males, 35% (CI 31%–39%), than females, 25% (CI 22%–28%). Almost 46% of participants were overweight; 19.7% were obese; 14.6% had hypercholesterolemia; 7.2% had diabetes mellitus and 17.8% smoked cigarettes. With the exception of cigarette smoking and low physical activity, all the CVD risk factors had significantly higher prevalence in the prehypertensive and hypertensive groups (p for trend < 0.001) compared to the normotensive group. Odds of obesity, overweight, high cholesterol and increased waist circumference were significantly higher among younger prehypertensive participants (15–44 years-old) when compared to normotensive young participants, but not among those 45–74 years-old. Among men, being prehypertensive increased the odds of having >/=3 CVD risk factors versus no risk factors almost three-fold (odds ratio [OR] 2.8 [CI 1.1–7.2]) while among women the odds of >/=3 CVD risk factors was increased two-fold (OR 2.0 [CI 1.3–3.8])</p> <p>Conclusion</p> <p>Prehypertension occurs in 30% of Jamaicans and is associated with increased prevalence of other CVD risk factors. Health-care providers should recognize the increased CVD risk of prehypertension and should seek to identify and treat modifiable risk factors in these persons.</p

Limitations of fasting indices in the measurement of insulin sensitivity in Afro-Caribbean adults

In young Afro-Caribbean adults, HOMA-IR compared poorly with other measures of insulin sensitivity. It remains important to determine whether similar findings occur in a more insulin resistant population. However, HOMA-IR correlated with clinical measures of insulin sensitivity (i.e. adiposity), so it may still be useful in epidemiological studies

Variability of extragalactic X-ray jets on kiloparsec scales

Unexpectedly strong X-ray emission from extragalactic radio jets on kiloparsec scales has been one of the major discoveries of Chandra, the only X-ray observatory capable of sub-arcsecond-scale imaging. The origin of this X-ray emission, which appears as a second spectral component from that of the radio emission, has been debated for over two decades. The most commonly assumed mechanism is inverse Compton upscattering of the Cosmic Microwave Background (IC-CMB) by very low-energy electrons in a still highly relativistic jet. Under this mechanism, no variability in the X-ray emission is expected. Here we report the detection of X-ray variability in the large-scale jet population, using a novel statistical analysis of 53 jets with multiple Chandra observations. Taken as a population, we find that the distribution of p-values from a Poisson model is strongly inconsistent with steady emission, with a global p-value of 1.96e-4 under a Kolmogorov-Smirnov test against the expected Uniform (0,1) distribution. These results strongly imply that the dominant mechanism of X-ray production in kpc-scale jets is synchrotron emission by a second population of electrons reaching multi-TeV energies. X-ray variability on the time-scale of months to a few years implies extremely small emitting volumes much smaller than the cross-section of the jet.Comment: Published in Nature Astronomy 29 May 2023; Supplemental Information and Excel File include

Differential effects of sertraline and cognitive behavioural therapy on behavioural inhibition in patients with obsessive compulsive disorder

© 2024 The Author(s). Published by Wolters Kluwer Health, Inc. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Patients with obsessive compulsive disorder (OCD) randomised to sertraline, manualised cognitive behavioural therapy (CBT), or combination (sertraline + CBT), underwent cognitive assessment. Cognitive testing was conducted at baseline and at week 16. The stop signal reaction time task (SSRT) was used to evaluate motor impulsivity and attentional flexibility was evaluated using the intra/extra-dimensional set shifting task. Paired-samples t-tests or nonparametric variants were used to compare baseline and posttreatment scores within each treatment group. Forty-five patients were tested at baseline (sertraline n = 14; CBT n = 14; sertraline + CBT n = 17) and 23 patients at week 16 (sertraline n = 6; CBT n = 7; sertraline + CBT n = 10). The mean dosage of sertraline was numerically higher in those taking sertraline as a monotherapy (166.67 mg) compared with those taking sertraline in combination with CBT (100 mg). Analysis of pre-post treatment scores using an intent-to-treat-analysis found a significant reduction in the SSRT in those treated with sertraline, whilst there was no significant change on this task for those treated with CBT or the combination. This study found that motor inhibition improved significantly following sertraline monotherapy. Suboptimal sertraline dosing might explain the failure to detect an effect on motor inhibition in the group receiving combination of sertraline + CBT. Higher dose sertraline may have broader cognitive effects than CBT for OCD, motor impulsivity may have value as a measure of treatment outcome and, by extension, the SSRT could serve as a biomarker for personalising care.Peer reviewe