A bolometric measurement of the antineutrino mass

High statistics calorimetric measurements of the beta spectrum of 187Re are being performed with arrays of silver perrhenate crystals operated at low temperature. After a modification of the experimental set-up, which allowed to substantially reduce the background of spurious counts and therefore to increase the sensitivity on the electron antineutrino mass, a new measurement with 10 silver perrhenate microbolometers is running since July 2002. The crystals have masses between 250 and 350 micrograms and their average FWHM energy resolution, constantly monitored by means of fluorescence X-rays, is of 28.3 eV at the beta end-point. The Kurie plot collected during 4485 hours x mg effective running time has an end-point energy of 2466.1 +/- 0.8{stat} +/- 1.5 {syst} eV, while the half lifetime of the decay is found to be 43.2 +/- 0.2{stat} +/- 0.1{syst} Gy. These values are the most precise obtained so far for 187Re. From the fit of the Kurie plot we can deduce a value for the squared electron antineutrino mass m(nu)^2 of 147 +/- 237{stat} +/- 90{syst} eV^2. The corresponding 90% C.L. upper limit for m(nu) is 21.7 eV.Comment: 3 pages, 3 figures. Submitted to Phys. Rev. Let

A comparison of dry and wet season aerosol number fluxes over the Amazon rain forest

Vertical number fluxes of aerosol particles and vertical fluxes of CO(2) were measured with the eddy covariance method at the top of a 53 m high tower in the Amazon rain forest as part of the LBA (The Large Scale Biosphere Atmosphere Experiment in Amazonia) experiment. The observed aerosol number fluxes included particles with sizes down to 10 nm in diameter. The measurements were carried out during the wet and dry season in 2008. In this study focus is on the dry season aerosol fluxes, with significant influence from biomass burning, and these are compared with aerosol fluxes measured during the wet season. Net particle deposition fluxes dominated in daytime in both seasons and the deposition flux was considerably larger in the dry season due to the much higher dry season particle concentration. The particle transfer velocity increased linearly with increasing friction velocity in both seasons. The difference in transfer velocity between the two seasons was small, indicating that the seasonal change in aerosol number size distribution is not enough for causing any significant change in deposition velocity. In general, particle transfer velocities in this study are low compared to studies over boreal forests. The reasons are probably the high percentage of accumulation mode particles and the low percentage of nucleation mode particles in the Amazon boundary layer, both in the dry and wet season, and low wind speeds in the tropics compared to the midlatitudes. In the dry season, nocturnal particle fluxes behaved very similar to the nocturnal CO(2) fluxes. Throughout the night, the measured particle flux at the top of the tower was close to zero, but early in the morning there was an upward particle flux peak that is not likely a result of entrainment or local pollution. It is possible that these morning upward particle fluxes are associated with emission of primary biogenic particles from the rain forest. Emitted particles may be stored within the canopy during stable conditions at nighttime, similarly to CO(2), and being released from the canopy when conditions become more turbulent in the morning.National Institute for Research in the Amazon (INPA)LBACNPq/MCTFAPES

Aerosol number fluxes over the Amazon rain forest during the wet season

Number fluxes of particles with diameter larger than 10 nm were measured with the eddy covariance method over the Amazon rain forest during the wet season as part of the LBA (The Large Scale Biosphere Atmosphere Experiment in Amazonia) campaign 2008. The primary goal was to investigate whether sources or sinks dominate the aerosol number flux in the tropical rain forest-atmosphere system. During the measurement campaign, from 12 March to 18 May, 60% of the particle fluxes pointed downward, which is a similar fraction to what has been observed over boreal forests. The net deposition flux prevailed even in the absolute cleanest atmospheric conditions during the campaign and therefore cannot be explained only by deposition of anthropogenic particles. The particle transfer velocity v(t) increased with increasing friction velocity and the relation is described by the equation v(t) = 2.4x10(-3)xu(*) where u(*) is the friction velocity. Upward particle fluxes often appeared in the morning hours and seem to a large extent to be an effect of entrainment fluxes into a growing mixed layer rather than primary aerosol emission. In general, the number source of primary aerosol particles within the footprint area of the measurements was small, possibly because the measured particle number fluxes reflect mostly particles less than approximately 200 nm. This is an indication that the contribution of primary biogenic aerosol particles to the aerosol population in the Amazon boundary layer may be low in terms of number concentrations. However, the possibility of horizontal variations in primary aerosol emission over the Amazon rain forest cannot be ruled out.National Institute for Research in the Amazon (INPA)LBA infrastructure teamCNPq/MCT Millennium Institute ProgramFAPES

First-Principles Studies of Hydrogenated Si(111)--7×\times7

The relaxed geometries and electronic properties of the hydrogenated phases of the Si(111)-7$\times$7 surface are studied using first-principles molecular dynamics. A monohydride phase, with one H per dangling bond adsorbed on the bare surface is found to be energetically favorable. Another phase where 43 hydrogens saturate the dangling bonds created by the removal of the adatoms from the clean surface is found to be nearly equivalent energetically. Experimental STM and differential reflectance characteristics of the hydrogenated surfaces agree well with the calculated features.Comment: REVTEX manuscript with 3 postscript figures, all included in uu file. Also available at http://www.phy.ohiou.edu/~ulloa/ulloa.htm

Enhancement of the electric dipole moment of the electron in BaF molecule

We report results of ab initio calculation of the spin-rotational Hamiltonian parameters including P- and P,T-odd terms for the BaF molecule. The ground state wave function of BaF molecule is found with the help of the Relativistic Effective Core Potential method followed by the restoration of molecular four-component spinors in the core region of barium in the framework of a non-variational procedure. Core polarization effects are included with the help of the atomic Many Body Perturbation Theory for Barium atom. For the hyperfine constants the accuracy of this method is about 5-10%.Comment: 8 pages, REVTEX, report at II International Symposium on Symmetries in Subatomic Physics, Seattle 199

Factors associated with lack of improvement in submaximal exercise capacity of patients with heart failure

Aims Improvement in exercise capacity is the primary goal of physical activity programmes for patients with heart failure (HF). Although activity programmes are effective for some patients, others do not benefit. Identifying factors related to a lack of improvement in submaximal exercise capacity may help us interpret findings and design new interventions. The aim of this study is to identify factors contributing to a lack of improvement in submaximal exercise capacity 3 months after physical activity advice or an exergame intervention in patients with HF. Additionally, we aimed to assess differences in lack of improvement in submaximal exercise capacity of patients whose baseline exercise capacity predicted a worse compared with better prognosis of HF.Methods and results This secondary analysis of the HF-Wii study analysed baseline and 3 month data of the 6 min walk test (6MWT) from 480 patients (mean age 67 years, 72% male). Data were analysed separately in patients with a pre-defined 6 min walking distance at baseline of <300 m (n = 79) and >= 300 m (n = 401). Among patients with a baseline 6MWT of >= 300 m, 18% had deteriorated submaximal exercise capacity. In the multiple logistic regression analysis, lower baseline levels of self-reported physical activity [odds ratio (OR) = 0.77, 95% confidence interval (CI) = 0.60-0.97], lower baseline levels of cognitive function (OR = 0.87, 95%CI = 0.79-0.96) were significantly associated with lack of improvement in exercise capacity at 3 months. Not randomized to exergaming (OR = 0.63, 95%CI = 0.37-1.09) was likely (P = 0.097) to be associated with lack of improvement in exercise capacity at 3 months. Among the 79 patients with baseline 6MWT of <300 m, 41% (n = 32) did not improve 6MWT distance at 3 months. Independent predictors for the lack of improvement for 6MWT were New York Heart Association class III/IV (OR = 4.68, 95%CI = 1.08-20.35), higher levels of serum creatinine (OR = 1.02, 95%CI = 1.003-1.03), lower cognitive function (OR = 0.86, 95%CI = 0.75-0.99), and fewer anxiety symptoms (OR = 0.84, 95%CI = 0.72-0.98).Conclusions Lower self-reported physical activity and cognitive impairment predict lack of improvement in submaximal exercise capacity in HF patients. Patients who have a worse prognosis (score <300 m at the 6MWT) are often frail and gain less in exercise capacity. These patients may need a more comprehensive approach to have an effect on exercise capacity, including an individually tailored exercise programme with aerobic exercise (if tolerated) and strength exercises

Atomic Parity Nonconservation: Electroweak Parameters and Nuclear Structure

There have been suggestions to measure atomic parity nonconservation (PNC) along an isotopic chain, by taking ratios of observables in order to cancel complicated atomic structure effects. Precise atomic PNC measurements could make a significant contribution to tests of the Standard Model at the level of one loop radiative corrections. However, the results also depend upon certain features of nuclear structure, such as the spatial distribution of neutrons in the nucleus. To examine the sensitivity to nuclear structure, we consider the case of Pb isotopes using various recent relativistic and non-relativistic nuclear model calculations. Contributions from nucleon internal weak structure are included, but found to be fairly negligible. The spread among present models in predicted sizes of nuclear structure effects may preclude using Pb isotope ratios to test the Standard Model at better than a one percent level, unless there are adequate independent tests of the nuclear models by various alternative strong and electroweak nuclear probes. On the other hand, sufficiently accurate atomic PNC experiments would provide a unique method to measure neutron distributions in heavy nuclei.Comment: 44 pages, INT Preprint DOE/ER/40561-050-INT92-00-1

Surface reconstruction induced geometries of Si clusters

We discuss a generalization of the surface reconstruction arguments for the structure of intermediate size Si clusters, which leads to model geometries for the sizes 33, 39 (two isomers), 45 (two isomers), 49 (two isomers), 57 and 61 (two isomers). The common feature in all these models is a structure that closely resembles the most stable reconstruction of Si surfaces, surrounding a core of bulk-like tetrahedrally bonded atoms. We investigate the energetics and the electronic structure of these models through first-principles density functional theory calculations. These models may be useful in understanding experimental results on the reactivity of Si clusters and their shape as inferred from mobility measurements.Comment: 9 figures (available from the author upon request) Submitted to Phys. Rev.

Calculation of PandP_ and T_ odd effects in $"" sup 205_TIF including electron correlation

A method and codes for two-step correlation calculation of heavy-atom molecules have been developed, employing the generalized relativistic effective core potential and relativistic coupled cluster (RCC) methods at the first step, followed by nonvariational one-center restoration of proper four-component spinors in the heavy cores. Electron correlation is included for the first time in an ab initio calculation of the interaction of the permanent P,T-odd proton electric dipole moment with the internal electromagnetic field in a molecule. The calculation is performed for the ground state of TlF at the experimental equilibrium, R_e=2.0844 A, and at R=2.1 A, with spin-orbit and correlation effects included by RCC. Calculated results with single cluster amplitudes only are in good agreement (3% and 1%) with recent Dirac-Hartree-Fock (DHF) values of the magnetic parameter M; the larger differences occurring between present and DHF volume parameter (X) values, as well as between the two DHF calculations, are explained. Inclusion of electron correlation by GRECP/RCC with single and double excitations has a major effect on the P,T-odd parameters, decreasing M by 17% and X by 22%.Comment: 5 pages, REVTeX4 style Accepted for publication in Phys.Rev.Letter

Effects of exergaming on exercise capacity in patients with heart failure: results of an international multicentre randomized controlled trial

Aims Exergaming is a new tool to increase physical activity. This study aimed to determine the effects of access to a home-based exergame (Nintendo Wii) in patients with heart failure (HF) on exercise capacity, self-reported physical activity and patient-reported outcome measures.Methods and results We enrolled 605 HF patients in New York Heart Association functional class I-IV, independent of ejection fraction, in an international multicentre randomized controlled trial. Patients were randomized to exergame (intervention) or motivational support (control). The primary endpoint was change in submaximal aerobic exercise capacity as measured by the distance walked in 6 min (6MWT) between baseline and 3 months. Secondary endpoints included long-term submaximal aerobic exercise capacity, muscle function, self-reported physical activity, exercise motivation, exercise self-efficacy at 3, 6 and 12months. At baseline, patients on average walked 403142m on the 6MWT. Patients in the exergame group walked further compared to controls at 3 months (454123 vs. 420 +/- 127m, P = 0.005), at 6 months (452 +/- 123 vs. 426 +/- 133m, P = 0.015) and 12months (456 +/- 122 vs. 420 +/- 135m, P = 0.004). However, correcting for baseline 6MWT values by means of a linear mixed-effects model revealed no main effect for the intervention on 6MWT. Small significant effects on muscle function were found. Statistically significant treatment effects were found for muscle function but after correction for baseline and confounders, only the treatment effect for the heel-rise left at 6 months was significant (P<0.05). No treatment effect was found for exercise motivation, exercise self-efficacy, or self-reported physical activity.ConclusionExergaming was safe and feasible in patients with HF with different profiles in different health care systems, cultures and climates. However, it was not effective in improving outcomes on submaximal aerobic exercise capacity. Subgroup analysis did not identify specific subgroups benefiting from the intervention.Clinical Trial Registration: Identifier: NCT01785121