Pseudo Goldstone Bosons Phenomenology in Minimal Walking Technicolor

We construct the non-linear realized Lagrangian for the Goldstone Bosons associated to the breaking pattern of SU(4) to SO(4). This pattern is expected to occur in any Technicolor extension of the standard model featuring two Dirac fermions transforming according to real representations of the underlying gauge group. We concentrate on the Minimal Walking Technicolor quantum number assignments with respect to the standard model symmetries. We demonstrate that for, any choice of the quantum numbers, consistent with gauge and Witten anomalies the spectrum of the pseudo Goldstone Bosons contains electrically doubly charged states which can be discovered at the Large Hadron Collider.Comment: 25 pages, 5 figure

Electrical activity of carbon-hydrogen centers in Si

The electrical activity of Cs-H defects in Si has been investigated in a combined modeling and experimental study. High-resolution Laplace capacitance spectroscopy with the uniaxial stress technique has been used to measure the stress-energy tensor and the results are compared with theoretical modeling. At low temperatures, implanted H is trapped as a negative-U center with a donor level in the upper half of the gap. However, at higher temperatures, H migrates closer to the carbon impurity and the donor level falls, crossing the gap. At the same time, an acceptor level is introduced into the upper gap making the defect a positive-U center

Determinants of guideline use in primary care physical therapy: a cross-sectional survey of attitudes, knowledge, and behavior

Background Understanding of attitudes, knowledge, and behavior related to evidence-based practice (EBP) and use of evidence-based clinical practice guidelines in primary care physical therapy is limited. Objectives The objectives of this study were: (1) to investigate self-reported attitudes, knowledge, behavior, prerequisites, and barriers related to EBP and guideline use among physical therapists in primary care and (2) to explore associations of self-reported use of guidelines with these social cognitive factors along with demographic and workplace characteristics. Design This was a cross-sectional survey. Methods A web-based survey of 419 physical therapists in primary care in western Sweden was performed. Multiple logistic regression analysis was performed to examine factors associated with guideline use. Results The response rate was 64.7%. Most respondents had positive attitudes toward EBP and guidelines: 90% considered EBP necessary, and 96% considered guidelines important. Approximately two thirds reported confidence in finding and using evidence. One third reported being aware of guidelines. Thirteen percent knew where to find guidelines, and only 9% reported having easy access to guidelines. Fewer than half reported using guidelines frequently. The most important barriers to using guidelines were lack of time, poor availability, and limited access to guidelines. Young age and brief work experience were associated with positive attitudes toward EBP. A postgraduate degree was associated with higher application of EBP. Positive attitudes, awareness of guidelines, considering guidelines to facilitate practice, and knowing how to integrate patient preferences with guideline use were associated with frequent use of guidelines. Limitations Data were self-reported, which may have increased the risk of social desirability bias. Conclusions Use of guidelines was not as frequent as could be expected in view of the positive attitudes toward EBP and guidelines among physical therapists. Awareness of and perceived access to guidelines were limited. The identified determinants can be addressed when developing guideline implementation strategies

Gastroesophageal Reflux after Vertical Banded Gastroplasty is Alleviated by Conversion to Gastric Bypass.

BACKGROUND: Conversion operations after vertical banded gastroplasty (VBG) are sometimes performed because of vomiting and/or acid regurgitation. Primary operation with gastric bypass (GBP) is known to reduce gastroesophageal reflux (GERD). Previous studies have not been designed to differentiate between the effects of the altered anatomy and of the ensuing weight loss. No series has reported data on acid reflux before and after conversion from VBG to GBP. METHODS: We invited eight VBG patients with current symptoms of GERD. All had intact staple lines as assessed by barium meal and gastroscopy. Acid reflux was quantified using 48-h Bravo capsule measurements. Conversion operations were performed creating an isolated 15-20-ml pouch; the previously banded part of gastric wall was excised. Gastrojejunostomy was made end to end with a 28-mm circular stapler. The study is based on five patients consenting to early postoperative endoscopy and pH measurement. RESULTS: All patients were women with a mean age of 49.5 years and BMI of 36.3. Time since VBG was 132.1 months. Time from conversion to second measurement was 46.6 days and BMI at that time 32.7. There was no mortality and no serious morbidity. All patients improved clinically and no patient had to go back on proton pump inhibition or antacids. Total time with pH < 4.0 was reduced from 18.4% to 3.3% (p < 0.05). DeMeester score was reduced from 58.1 to 15.9 (p < 0.05). CONCLUSIONS: The effect of converting VBG-operated patients to GBP results in a near-normalisation of acid reflux parameters and a discontinuation of proton pump inhibitor medication

Calculated properties of nitrogen-vacancy complexes in beryllium- and magnesium-doped GaN

The properties of defect complexes consisting of a nitrogen vacancy with a substitutional beryllium or magnesium atom on neighboring lattice sites in hexagonal GaN are calculated using the AIMPRO local-density-functional theory method. Both types of defects VN−BeGa and VN−MgGa are bound with respect to their isolated constituents. They do not appear to have any electronic levels in the bandgap, and are expected to be neutral defects. Important structural differences are found. In its minimum energy configuration, the Be atom in the VN−BeGa complex lies nearly in the same plane as the three equivalent N atoms nearest to it. Thus, it has shorter Be−N bonds than the Ga−N distance in the bulk crystal, while the Mg atom in the VN−MgGa complex occupies a position closer the lattice site of the Ga atom it replaces. Hence, the VN−BeGa complex has a larger open volume than the VN−MgGa complex. This is consistent with positron annihilation experiments [Saarinen et al., J. Cryst. Growth 246, 281 (2002); Hautakangas et al., Phys. Rev. Lett. 90, 137402 (2003)]. The frequency of the highest local vibrational mode of the VN−BeGa center is calculated to be within 3–4 % of an infrared absorption line detected in Be-doped GaN [Clerjaud (private communication)].Peer reviewe

A study of methyl formate in astrochemical environments

Several complex organic molecules are routinely detected in high abundances towards hot cores and hot corinos. For many of them, their paths of formation in space are uncertain, as gas phase reactions alone seem to be insufficient. In this paper, we investigate a possible solid-phase route of formation for methyl formate (HCOOCH3). We use a chemical model updated with recent results from an experiment where simulated grain surfaces were irradiated with 200 keV protons at 16 K, to simulate the effects of cosmic ray irradiation on grain surfaces. We find that this model may be sufficient to reproduce the observed methyl formate in dark clouds, but not that found in hot cores and corinos.Comment: 6 pages, 2 figures, 2 tables Accepted by MNRA

Passivation of copper in silicon by hydrogen

The structures and energies of model defects consisting of copper and hydrogen in silicon are calculated using the AIMPRO local-spin-density functional method. For isolated copper atoms, the lowest energy location is at the interstitial site with Td symmetry. Substitutional copper atoms are found to adopt a configuration with D2d symmetry. We conclude that the symmetry is lowered from Td due to the Jahn-Teller effect. Interstitial hydrogen atoms are found to bind strongly to substitutional copper atoms with an energy that is more than the difference in formation energy over the interstitial site for Cu. The resulting complex has C2v symmetry in the −2 charge state where the H atom is situated about 1.54 Å away from the Cu atom in a [100] direction. In other charge states the symmetry of the defect is lowered to Cs or C1. A second hydrogen atom can bind to this complex with nearly the same energy as the first. Two structures are found for copper dihydride complexes that have nearly equal energies; one with C2 symmetry, and the other with Cs symmetry. The binding energy for a third hydrogen atom is slightly more than for the first. Calculated electronic levels for the model defects relative to one another are found to be in fair to good agreement with experimental data, except for the copper-dihydride complex. The copper trihydride complex has no deep levels in the bandgap, according to our calculations.Peer reviewe

Methanol ice co-desorption as a mechanism to explain cold methanol in the gas-phase

Context. Methanol is formed via surface reactions on icy dust grains. Methanol is also detected in the gas-phase at temperatures below its thermal desorption temperature and at levels higher than can be explained by pure gas-phase chemistry. The process that controls the transition from solid state to gas-phase methanol in cold environments is not understood. Aims. The goal of this work is to investigate whether thermal CO desorption provides an indirect pathway for methanol to co-desorb at low temperatures. Methods. Mixed CH₃OH:CO/CH₄ ices were heated under ultra-high vacuum conditions and ice contents are traced using RAIRS (reflection absorption IR spectroscopy), while desorbing species were detected mass spectrometrically. An updated gas-grain chemical network was used to test the impact of the results of these experiments. The physical model used is applicable for TW Hya, a protoplanetary disk in which cold gas-phase methanol has recently been detected. Results. Methanol release together with thermal CO desorption is found to be an ineffective process in the experiments, resulting in an upper limit of ≤ 7.3 × 10−7 CH₃OH molecules per CO molecule over all ice mixtures considered. Chemical modelling based on the upper limits shows that co-desorption rates as low as 10−6 CH₃OH molecules per CO molecule are high enough to release substantial amounts of methanol to the gas-phase at and around the location of the CO thermal desorption front in a protoplanetary disk. The impact of thermal co-desorption of CH₃OH with CO as a grain-gas bridge mechanism is compared with that of UV induced photodesorption and chemisorption