Uniaxial pressure dependencies of the phase transitions in GdMnO3_3

GdMnO$_3$ shows an incommensurate antiferromagnetic order below $\simeq 42$ K, transforms into a canted A-type antiferromagnet below $\simeq 20$ K, and for finite magnetic fields along the b axis ferroelectric order occurs below $\simeq 12$ K. From high-resolution thermal expansion measurements along all three principal axes, we determine the uniaxial pressure dependencies of the various transition temperatures and discuss their correlation to changes of the magnetic exchange couplings in $R$MnO$_3$ ($R = {\rm La, ... Dy}$).Comment: 2 pages, 3 figures, submitted to JMMM (Proceedings of ICM'06, Kyoto

Improving Pulsar Timing through Interstellar Scatter Correction

Though pulsar timing has confirmed the existence of gravitational waves, no technique has directly detected them. Jenet et al. state the requirements for the Parkes Pulsar Timing Array (PPTA) to make a significant detection of the stochastic gravitational wave background within five years. By employing the scintillation information in observations for each pulsar at every epoch, I believe interstellar scattering, an underestimated source of timing noise, can be corrected enough for the PPTA to meet these requirements. The improved detection threshold will help answer important questions about black hole mergers, galaxy evolution, and gravitation

Critical speeding-up near the monopole liquid-gas transition in magnetoelectric spin-ice

Competing interactions in the so-called spin-ice compounds stabilize a frustrated ground-state with finite zero-point entropy and, interestingly, emergent magnetic monopole excitations. The properties of these monopoles are at the focus of recent research with particular emphasis on their quantum dynamics. It is predicted that each monopole also possesses an electric dipole moment, which allows to investigate their dynamics via the dielectric function \epsilon(\nu). Here, we report on broadband spectroscopic measurements of \epsilon(\nu) in Dy2Ti2O7 down to temperatures of 200mK with a specific focus on the critical endpoint present for a magnetic field along the crystallographic [111] direction. Clear critical signatures are revealed in the dielectric response when, similarly as in the liquid-gas transition, the density of monopoles changes in a critical manner. Surprisingly, the dielectric relaxation time \tau\ exhibits a critical speeding-up with a significant enhancement of 1/\tau\ as the temperature is lowered towards the critical temperature. Besides demonstrating the magnetoelectric character of the emergent monopole excitations, our results reveal unique critical dynamics near the monopole condensation transition.Comment: Changes: Data shown and discussed as function of internal field H and flux density B, Figs.3&4 rearranged, references adde

Improving Pulsar Timing through Interstellar Scatter Correction

Though pulsar timing has confirmed the existence of gravitational waves, no technique has directly detected them. Jenet et al. state the requirements for the Parkes Pulsar Timing Array (PPTA) to make a significant detection of the stochastic gravitational wave background within five years. By employing the scintillation information in observations for each pulsar at every epoch, I believe interstellar scattering, an underestimated source of timing noise, can be corrected enough for the PPTA to meet these requirements. The improved detection threshold will help answer important questions about black hole mergers, galaxy evolution, and gravitation

Melodic Sketch : In A

https://digitalcommons.library.umaine.edu/mmb-ps/1102/thumbnail.jp

The neuropsychology of obsessive-compulsive symptoms

Obsessive-compulsive (OC) symptoms occur in a variety of clinical conditions, but the underlying pathogenesis of these symptoms remains elusive. Few neuropsychological investigations have compared idiopathic Obsessive-Compulsive Disorder (OCD) with patient groups where OC symptoms are acquired. The present study investigated the neuropsychological correlates of OC symptoms in OCD and frontotemporal dementia (FTD), a neurodegenerative illness in which OC symptoms are often acquired. Neuroimaging in OCD has consistently implicated the frontal-striatal-thalamic circuit, particularly the orbitofrontal cortex and basal ganglia. These areas overlap considerably with the sites of cerebral pathology found in FTD. OCD has been associated with a number of neuropsychological deficits, with most consistent findings pointing towards impaired executive function (EF), and less commonly reported deficits in visual memory and visuospatial ability. The neuropsychological hallmark of FTD is deficits in EF. However in both OCD and FTD, the relationship between cognitive deficits and OC symptoms remains unclear. Further, the extent to which OC symptoms are comparable between the groups is ambiguous. Part I of the present study compared 19 OCD subjects to 20 age, education and IQ-matched healthy controls on a battery of neuropsychological tests of all major cognitive domains with emphasis on EF. A measure of Theory of Mind (ToM) thought to be sensitive to orbitofrontal function was also administered. OCD subjects performed worse than controls on a measure of visual memory, visuospatial reasoning and on only one measure of EF. OCD symptom subtypes, as measured by the Obsessive-Compulsive Inventory (OCI), were not correlated with any cognitive deficits. No group differences in ToM were found. It is suggested that prior research has overestimated the severity and significance of EF deficits in OCD. Part II of the study compared 9 FTD participants with 10 matched healthy controls on the same neuropsychological test battery and OC symptom measures. In addition, a measure of compulsive behaviours used in neurological populations was administered to carers. While the incidence of OC symptoms was comparable to reports in previous studies (78%), the OCI was not sensitive in the detection of OC symptoms in FTD. The similarities and differences in OC symptoms between the two patient groups are discussed

Multiferroicity and colossal magneto-capacitance in Cr-thiospinels

The sulfur based Cr-spinels RCr2S4 with R = Cd and Hg exhibit the coexistence of ferromagnetic and ferroelectric properties together with a pronounced magnetocapacitive coupling. While in CdCr2S4 purely ferromagnetic order is established, in HgCr2S4 a bond-frustrated magnetic ground state is realized, which, however, easily can be driven towards a ferromagnetic configuration in weak magnetic fields. This paper shall review our recent investigation for both compounds. Besides the characterization of the magnetic properties, the complex dielectric permittivity was studied by means of broadband dielectric spectroscopy as well as measurements of polarization hysteresis and pyro-currents. The observed colossal magneto-capacitive effect at the magnetic transition seems to be driven by an enormous variation of the relaxation dynamics.Comment: 10 pages, 11 figure

Occupational Therapy Practice Trends for Occupations Impacted by Puberty in Children with ASD

Introduction: Adolescents face physical, social, cognitive, and emotional changes during the developmental stage of puberty. Pubertal changes can be difficult for neurotypical adolescents to cope with, but especially for individuals with autism spectrum disorder (ASD). Specifically, adolescents with ASD experience challenges with adapting to physical and emotional changes, managing new hygiene routines, abiding to social norms, and inappropriate sexual behaviors (Beddows & Brooks, 2016; Cridland, Caputi, Jones, & Magee, 2015; Cridland, Jones, Caputi, & Magee, 2014). While occupational therapy plays a role in helping adolescents with ASD, a lack of occupational therapy literature on this topic leads to unknown practice trends for practitioners to address puberty-related challenges in individuals with ASD. The purpose of this independent study was to understand the trends of occupational therapy practitioners in addressing developmental changes during puberty for adolescents with ASD. Methodology: A descriptive survey design was used. The Occupational Therapy for Autism and Puberty Survey (OT-APS) was developed based upon a literature review to understand best practices in ASD. Stratified random sampling and convenience sampling were employed with 71 occupational therapy practitioners responding to the descriptive survey. Results and Conclusions: Practice trends gleaned from the survey include: a) The most common assessments used were the Sensory Profile 2 (69.0%), the Sensory Processing vii Measure (63.4%), and the BOT-2 (62.0%). b) The most common interventions practitioners have been trained in were behavioral strategies (94.4%), sensory processing integration (81.7%), and social learning approaches (80.3%). c) The interventions most often used included social learning approaches (M= 5.30, SD = 2.86) and behavioral strategies (M = 5.28, SD = 2.65). d) Practitioners were most comfortable addressing emotional regulation (54.9%) and personal hygiene and self-care (58%) and least comfortable addressing masturbation (88. 7%) and menstruation ( 42.8% ). e) Practitioners were most comfortable using behavioral strategies (56.3%) and social learning approaches (46.5%). Significance: This research study provided evidence regarding the training completed, challenges addressed, interventions used, and comfortability of occupational therapy practitioners to address puberty related changes and challenges with children and adolescents age 8-16 with ASD. The findings provide an understanding of current practice trends and can be compared with best practice approaches and help identify evidence-based interventions that are being more or less utilized. Further research is needed better understand how these interventions are being provided in practice and why interventions are more often or rarely used. The information can be used in determining whether occupational therapy practitioners require further training in and understanding of puberty related changes and challenges within this population