Superconducting Cosmc Strings and Primordial Magnetic Fields

We consider grand unified theories with superconducting cosmic strings and which admit the mechanism for generating primordial magnetic fields recently discussed by Vachaspati. We show that these models are severely constrained by cosmological arguments. Quite generically, either stable springs or vortons will form. Provided the mass per unit length of the strings is sufficiently large, these stable configurations will overclose the Universe.Comment: BROWN-HET-830, 14 pages, use phyzz

Inflation in Supersymmetric Cosmic String Theories

We examine a non-Abelian SUSY $SU(2) \times U(1)$ gauge theory and a SUSY U(1) theory originally used to investigate the microphysics of cosmic strings in supersymmetric theories. We show that both theories automatically include hybrid inflation. In the latter theory we use a $D$ term to break the symmetry. SUSY is broken during inflation and restored afterwards. Cosmic strings are formed at the end of inflation. The temperature anisotropy is calculated and found to vary as $(M_{GUT}/M_P)^2$.Comment: 5 page

Impaired thermoregulatory function during dynamic exercise in multiple sclerosis

INTRODUCTION: Impairments in sudomotor function during passive whole-body heating have been reported in multiple sclerosis (MS), a demyelinating disease of the CNS that disrupts autonomic function. However, the capability of the thermoregulatory system to control body temperature during exercise has never been assessed in MS. Thus, the aim of the present study was to test the hypothesis that thermoregulatory function is impaired in MS patients compared to healthy controls (CON) exercising at similar rates of metabolic heat production. METHODS: Sweating and skin blood flow responses were compared between 12 individuals diagnosed with relapsing-remitting MS (9 females, 3 males) and 12 sex-, age-, mass- and BSA-matched healthy controls during a single bout of cycling exercise (rate of metabolic heat production: ~4.5 W/kg) for 60 min in a climate-controlled room (25 °C, 30% RH). RESULTS: Individuals with MS exhibited an attenuated increase in cumulative whole-body sweat loss after 30 min (MS: 72 ± 51; CON: 104 ± 37 g, p=0.04) and 60 min (MS: 209 ± 94; CON: 285 ± 62 g, p=0.02), as well as lower sweating thermosensitivity (MS: 0.49 ± 0.26; CON: 0.86 ± 0.30 mg/cm2/min/°C, p=0.049). Despite evidence for thermoregulatory dysfunction, there were no differences between MS and CON in esophageal or rectal temperatures at 30 or 60 min time points (p>0.05). Cutaneous vasculature responses were also not different in MS compared to CON (p>0.05). CONCLUSION: Taken together, MS blunts sweating responses during exercise while cutaneous vasculature responses are preserved. Altered mechanisms of body temperature regulation in persons with MS may lead to temporary worsening of disease symptoms and limit exercise tolerance under more thermally challenging conditions.Accepted manuscrip

Insights on the Spectral Signatures of Stellar Activity and Planets from PCA

Photospheric velocities and stellar activity features such as spots and faculae produce measurable radial velocity signals that currently obscure the detection of sub-meter-per-second planetary signals. However, photospheric velocities are imprinted differently in a high-resolution spectrum than Keplerian Doppler shifts. Photospheric activity produces subtle differences in the shapes of absorption lines due to differences in how temperature or pressure affects the atomic transitions. In contrast, Keplerian Doppler shifts affect every spectral line in the same way. With high enough S/N and high enough resolution, statistical techniques can exploit differences in spectra to disentangle the photospheric velocities and detect lower-amplitude exoplanet signals. We use simulated disk-integrated time-series spectra and principal component analysis (PCA) to show that photospheric signals introduce spectral line variability that is distinct from Doppler shifts. We quantify the impact of instrumental resolution and S/N for this work.Comment: 12 pages, 7 figures, accepted to Ap

Sleep Characteristics in Patients with Whiplash-Associated Disorders: A Descriptive Study

Study Objectives: The purpose of this study was to explore sleep habits and characteristics of patients with whiplash-associated disorders (WAD) presenting at an outpatient, chiropractic clinic using the Medical Outcomes Study (MOS) Sleep Scale. Methods: Fifty-one patients from an outpatient chiropractic and physical therapy clinic specializing in spinal rehabilitation participated in this cross-sectional, descriptive study. Data were collected using a descriptive survey, the Visual Analog Scale (VAS), the Neck Disability Index (NDI), and the self-administered 12-item MOS Sleep Scale. Data analysis included descriptive statistics to describe pain, disability, and sleep characteristics of the study sample, and computation of confidence intervals to determine differences in means of sleep characteristics between the non-WAD population (as determined by previous studies) and the study sample of WAD patients. Results: Results indicate that when compared to normative values of the non-WAD population, the sample of WAD patients in this study presents with significantly greater measures of neck disability (NDI), neck pain (VAS), sleep disturbance, snoring, shortness of breath and headache, sleep somnolence and sleep problems index I and II. This sample also presents with significantly lower measures of optimal sleep when compared to the general population. Conclusion: Consistent with previous research, findings from this study indicate that WAD patients have increased neck disability and pain, and poorer sleep outcomes, indicating the need for clinicians to assess sleep characteristics and incorporate interventions aimed at alleviating these symptoms when planning rehabilitation. Findings provide evidence for the need to further explore sleep disturbances among WAD patients to establish a stronger understanding of the course and prognosis of this condition

Measurement of net electric charge and dipole moment of dust aggregates in a complex plasma

Understanding the agglomeration of dust particles in complex plasmas requires a knowledge of the basic properties such as the net electrostatic charge and dipole moment of the dust. In this study, dust aggregates are formed from gold coated mono-disperse spherical melamine-formaldehyde monomers in a radio-frequency (rf) argon discharge plasma. The behavior of observed dust aggregates is analyzed both by studying the particle trajectories and by employing computer models examining 3D structures of aggregates and their interactions and rotations as induced by torques arising from their dipole moments. These allow the basic characteristics of the dust aggregates, such as the electrostatic charge and dipole moment, to be determined. It is shown that the experimental results support the predicted values from computer models for aggregates in these environments.Comment: 6 pages, 7 figure

Radiation constraints from cosmic strings

We show that it is possible to evolve a network of global strings numerically including the effects of radiative backreaction, using the renormalised equations for the Kalb-Ramond action. We calculate radiative corrections to the equations of motion and deduce the effect on a network of global strings. We also discuss the implications of this work for the cosmological axion density.Comment: 4 Pages, UUencoded postscript file, to appear in 'Trends in Astro-Particle Physics - Nuclear Physics B, Proceedings Supplement

One Loop Vaccum Polarization in a Locally de Sitter Background

We compute the one loop vacuum polarization from massless, minimally coupled scalar QED in a locally de Sitter background. Gauge invariance is maintained through the use of dimensional regularization, whereas conformal invariance is explicitly broken by the scalar kinetic term as well as through the conformal anomaly. A fully renormalized result is obtained. The one loop corrections to the linearized, effective field equations do not vanish when evaluated on-shell. In fact the on-shell one loop correction depends quadratically on the inflationary scale factor, similar to a photon mass. The contribution from the conformal anomaly is insignificant by comparison.Comment: 31 pages, LaTeX 2 epsilon, 4 figure