Gravitational wave signatures from kink proliferation on cosmic (super-) strings

Junctions on cosmic string loops give rise to the proliferation of sharp kinks. We study the effect of this proliferation on the gravitational wave (GW) signals emitted from string networks with junctions, assuming a scaling solution. We calculate the rate of occurrence and the distribution in amplitude of the GW bursts emitted at cusps and kinks in the frequency bands of LIGO and LISA as a function of the string tension, the number of sharp kinks on loops with junctions and the fraction of loops in the cosmological network which have junctions. Combining our results with current observational constraints, we find that pulsar data rule out a significant number of kinks on loops for strings with tensions G\mu > 10^{-12}. By contrast, for smaller tensions current observations allow for a large number of kinks on loops. If this is the case, the incoherent superposition of small bursts emitted at kink-kink encounters leads to an enhanced GW background that hides the strong individual bursts from kinks and cusps.Comment: 32 pages, 13 figure

Hematite to magnetite reduction monitored by Mo¨ssbauer spectroscopy and X-ray diffraction

Abstract The aim of the present research is to determine the kinetics of the transformation from hematite (a-Fe 2 O 3 ) to magnetite (Fe 3 O 4 ). The procedure consisted of an isothermal heating in a flow of a H 2 -Ar mixture at temperatures between 260 and 360 1C. The phase evolution at a given temperature, as a function of the thermal treatment time, was monitored by using room temperature Mo¨ssbauer spectroscopy and X-ray diffraction analysis (XRD). In the range of temperatures and times studied the only iron oxide that was formed was magnetite. In order to optimize equipment requirements for the quantification of the reaction products a calibration curve was constructed. This allows to estimate the conversion degree (measured as the percentage of magnetite produced) with a short-run XRD pattern. We calculate an apparent activation energy of 9874 kJ/mol from reaction grade-time curves at each temperature.

Cinética de reacción entre Zr y CI₄Zr monitoreada por correlaciones angulares perturbadas

Se presenta una descripción de la utilización de la técnica de Correlaciones Angulares Perturbadas Diferenciales en el Tiempo (TDPAC) para monitorear el progreso de la reacción química entre Zr metálico y tetracloruro de circonio. Los reactantes, dopados con 181Hf, fueron encerrados en vacio en un reactor de cuarzo. Las mediciones se realizaron a temperatura ambiente después de mantener durante varias horas el reactor con su extremo inferior, donde se alojaba el Zr metálico, a 800 °C y el resto del reactor a una temperatura superior a 400 °C, para asegurar la existencia del tetracloruro en forma gaseosa. Se utilizó la espectroscopia gamma simple como forma de estimar la cantidad de cada reactante que existía en las etapas de la reacción, tomando ventaja de la posibilidad de evaporar el tetracloruro remanente y condensarlo en un extremo del reactor, mientras el Zr y productos de reacción quedaban en el otro extremo.An application of the Time Differential Perturbed Angular Correlation (TDPAC) technique for monitoring the progress of the Chemical reaction between metallic Zr and ZrCl₄ is presenled. Reactants (doped with 181Hf ) were enclosed in vacuum in a quartz reactor. After keeping the reactor during severa! hours in a temperature gradient measurements were carried out at room temperature. The temperature gradient was established in the following way: the lower end of the reactor, where the metallic Zr stood, was kept at 800 °C and the rest of the reactor was kept at a temperature higher than 400 °C, to maintain the Cl₄Zr in gaseous State. Simple gamma spectroscopy was used to check the amount of reactants existing at each process step, taking advantage of the possibility of condensing the remnant tetrachloride in the upper end of the reactor.Facultad de Ciencias ExactasComisión de Investigaciones Científicas de la provincia de Buenos Aire

Same-Day Physical Therapy Consults in an Outpatient Neuromuscular Disease Physician Clinic

Background: Team-based care has been shown to offer more comprehensive benefits to patients when compared to standard physician-based care alone in clinics for chronic conditions. However, apart from grant-funded multidisciplinary clinics, there are no reports on the usage of same-day physical therapy (PT) consults within a daily outpatient neuromuscular disease (NMD) physician clinic. Objective: To determine the impact of same-day PT consults at the University of Utah’s outpatient Clinical Neurosciences Center. Design: A qualitative assessment and survey of patient satisfaction. Methods: An eight question Health Insurance Portability and Accountability Act-compliant patient satisfaction survey using a 5-point Likert scale was administered. Demographic data and Press-Ganey Provider Satisfaction surveys were retrospectively collected from electronic medical records for patients receiving same-day PT encounters in the neuromuscular division over 1 year. Results: Mean (standard deviation) age was 54.22 (19.81) years for 134 patient encounters, median age was 60 years, with 76 male (57%) and 58 female (43%) patients. Mean Likert score for 61 self-reported patient satisfaction surveys for same-day PT consults was 4.87 (97.4%). Press-Ganey Provider Satisfaction scores improved from 89.9% (N=287) for the year prior to 90.8% (N=320) for the corresponding year (P=0.427). A total of 46 (75.4%) patients have either never before received PT care or never before received PT care for their NMD, 67.4% of whom were male. Conclusion: Same-day PT consults in an outpatient NMD physician clinic demonstrated excellent patient satisfaction and improved access to specialty care. This model could potentially be implemented in other academic medical centers to improve access to rehabilitation services for patients with NMD

Seeking String Theory in the Cosmos

We review the existence, formation and properties of cosmic strings in string theory, the wide variety of observational techniques that are being employed to detect them, and the constraints that current observations impose on string theory models.Comment: 25 pages; contribution for String Cosmology issue of Classical and Quantum Gravity. References added and other improvements. Matches journal versio

Spin–orbit precession for eccentric black hole binaries at first order in the mass ratio

We consider spin–orbit ('geodetic') precession for a compact binary in strong-field gravity. Specifically, we compute ψ, the ratio of the accumulated spin-precession and orbital angles over one radial period, for a spinning compact body of mass m 1 and spin s 1, with ${{s}_{1}}\ll Gm_{1}^{2}/c$ , orbiting a non-rotating black hole. We show that ψ can be computed for eccentric orbits in both the gravitational self-force and post-Newtonian frameworks, and that the results appear to be consistent. We present a post-Newtonian expansion for ψ at next-to-next-to-leading order, and a Lorenz-gauge gravitational self-force calculation for ψ at first order in the mass ratio. The latter provides new numerical data in the strong-field regime to inform the effective one-body model of the gravitational two-body problem. We conclude that ψ complements the Detweiler redshift z as a key invariant quantity characterizing eccentric orbits in the gravitational two-body problem

First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto- noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far

Skeletal Muscle Myofibrillar and Sarcoplasmic Protein Synthesis Rates Are Affected Differently by Altitude-Induced Hypoxia in Native Lowlanders

As a consequence to hypobaric hypoxic exposure skeletal muscle atrophy is often reported. The underlying mechanism has been suggested to involve a decrease in protein synthesis in order to conserve O2. With the aim to challenge this hypothesis, we applied a primed, constant infusion of 1-13C-leucine in nine healthy male subjects at sea level and subsequently at high-altitude (4559 m) after 7–9 days of acclimatization. Physical activity levels and food and energy intake were controlled prior to the two experimental conditions with the aim to standardize these confounding factors. Blood samples and expired breath samples were collected hourly during the 4 hour trial and vastus lateralis muscle biopsies obtained at 1 and 4 hours after tracer priming in the overnight fasted state. Myofibrillar protein synthesis rate was doubled; 0.041±0.018 at sea-level to 0.080±0.018%⋅hr−1 (p<0.05) when acclimatized to high altitude. The sarcoplasmic protein synthesis rate was in contrast unaffected by altitude exposure; 0.052±0.019 at sea-level to 0.059±0.010%⋅hr−1 (p>0.05). Trends to increments in whole body protein kinetics were seen: Degradation rate elevated from 2.51±0.21 at sea level to 2.73±0.13 µmol⋅kg−1⋅min−1 (p = 0.05) at high altitude and synthesis rate similar; 2.24±0.20 at sea level and 2.43±0.13 µmol⋅kg−1⋅min−1 (p>0.05) at altitude. We conclude that whole body amino acid flux is increased due to an elevated protein turnover rate. Resting skeletal muscle myocontractile protein synthesis rate was concomitantly elevated by high-altitude induced hypoxia, whereas the sarcoplasmic protein synthesis rate was unaffected by hypoxia. These changed responses may lead to divergent adaptation over the course of prolonged exposure

Effectiveness of Chest Physiotherapy in Infants Hospitalized with Acute Bronchiolitis: A Multicenter, Randomized, Controlled Trial

Vincent Gajdos and colleagues report results of a randomized trial conducted among hospitalized infants with bronchiolitis. They show that a physiotherapy technique (increased exhalation and assisted cough) commonly used in France does not reduce time to recovery in this population