Gravitational time advancement and its possible detection

The gravitational time advancement is a natural but a consequence of curve space-time geometry. In the present work the expressions of gravitational time advancement have been obtained for geodesic motions. The situation when the distance of signal travel is small in comparison to the distance of closest approach has also been considered. The possibility of experimental detection of time advancement effect has been explored.Comment: 5 pages, 4 figures, a part of the work has been changed in the revised versio

Testing gravity to second post-Newtonian order: a field-theory approach

A new, field-theory-based framework for discussing and interpreting tests of gravity, notably at the second post-Newtonian (2PN) level, is introduced. Contrary to previous frameworks which attempted at parametrizing any conceivable deviation from general relativity, we focus on the best motivated class of models, in which gravity is mediated by a tensor field together with one or several scalar fields. The 2PN approximation of these "tensor-multi-scalar" theories is obtained thanks to a diagrammatic expansion which allows us to compute the Lagrangian describing the motion of N bodies. In contrast with previous studies which had to introduce many phenomenological parameters, we find that the 2PN deviations from general relativity can be fully described by only two new 2PN parameters, epsilon and zeta, beyond the usual (Eddington) 1PN parameters beta and gamma. It follows from the basic tenets of field theory, notably the absence of negative-energy excitations, that (beta-1), epsilon and zeta (as well as any new parameter entering higher post-Newtonian orders) must tend to zero with (gamma-1). It is also found that epsilon and zeta do not enter the 2PN equations of motion of light. Therefore, light-deflection or time-delay experiments cannot probe any theoretically motivated 2PN deviation from general relativity, but they can give a clean access to (gamma-1), which is of greatest significance as it measures the basic coupling strength of matter to the scalar fields. Because of the importance of self-gravity effects in neutron stars, binary-pulsar experiments are found to constitute a unique testing ground for the 2PN structure of gravity. A simplified analysis of four binary pulsars already leads to significant constraints: |epsilon| < 7x10^-2, |zeta| < 6x10^-3.Comment: 63 pages, 11 figures.ps.tar.gz.uu, REVTeX 3.

Gas diffusion through columnar laboratory sea ice: implications for mixed-layer ventilation of CO₂ in the seasonal ice zone

Gas diffusion through the porous microstructure of sea ice represents a pathway for ocean–atmosphere exchange and for transport of biogenic gases produced within sea ice. We report on the experimental determination of the bulk gas diffusion coefficients, D, for oxygen (O2) and sulphur hexafluoride (SF6) through columnar sea ice under constant ice thickness conditions for ice surface temperatures between -4 and -12 °C. Profiles of SF6 through the ice indicate decreasing gas concentration from the ice/water interface to the ice/air interface, with evidence for solubility partitioning between gas-filled and liquid-filled pore spaces. On average, DSF6 inline image was 1.3 × 10-4 cm2 s-1 (±40%) and DO2 was 3.9 × 10-5 cm2 s-1 (±41%). The preferential partitioning of SF6 to the gas phase, which is the dominant diffusion pathway produced the greater rate of SF6 diffusion. Comparing these estimates of D with an existing estimate of the air–sea gas transfer through leads indicates that ventilation of the mixed layer by diffusion through sea ice may be negligible, compared to air–sea gas exchange through fractures in the ice pack, even when the fraction of open water is less than 1%

Dominant next-to-leading order QCD corrections to Higgs plus three jet production in vector-boson fusion

We present the calculation of the dominant next to leading order QCD corrections to Higgs boson production in association with three jets via vector boson fusion in the form of a NLO parton-level Monte Carlo program. QCD corrections to integrated cross sections are modest, while the shapes of some kinematical distributions change appreciably at NLO. Scale uncertainties are shown to be reduced at NLO for the total cross section and for distributions. We consider a central jet veto at the LHC and analyze the veto probability for typical vector boson fusion cuts. Scale uncertainties of the veto probability are sufficiently small at NLO for precise Higgs coupling measurements at the LHC.Comment: 40 pages, 17 figures, 2 tables, published versio

Quantum feedback with weak measurements

The problem of feedback control of quantum systems by means of weak measurements is investigated in detail. When weak measurements are made on a set of identical quantum systems, the single-system density matrix can be determined to a high degree of accuracy while affecting each system only slightly. If this information is fed back into the systems by coherent operations, the single-system density matrix can be made to undergo an arbitrary nonlinear dynamics, including for example a dynamics governed by a nonlinear Schr\"odinger equation. We investigate the implications of such nonlinear quantum dynamics for various problems in quantum control and quantum information theory, including quantum computation. The nonlinear dynamics induced by weak quantum feedback could be used to create a novel form of quantum chaos in which the time evolution of the single-system wave function depends sensitively on initial conditions.Comment: 11 pages, TeX, replaced to incorporate suggestions of Asher Pere

Electroanatomical mapping-guided left bundle branch area pacing in patients with structural heart disease and advanced conduction abnormalities

Aims Left bundle branch area pacing (LBBAP) can be technically challenging and fluoroscopy-intense. Three-dimensional electroanatomical mapping (EAM) facilitates non-fluoroscopic lead navigation and electrogram mapping. We sought to prospectively evaluate the feasibility, safety, and outcomes of routine EAM-guided LBBAP in patients with structural heart disease (SHD) and advanced conduction abnormalities. Methods and results Consecutive patients with SHD and conduction abnormalities who underwent an attempt at EAM-guided LBBAP were included. The feasibility, safety, procedural, and mid-term outcomes were evaluated. Electrical, echocardiographic, and clinical parameters were assessed at implantation and last follow-up. Thirty-two patients (68 +/- 18 years; 19% female) were included, of which 75% had intrinsic QRS > 150 ms, 53% left bundle branch block, and 25% right bundle branch block. Primary EAM-guided LBBAP was successful in 29 patients (91%). The procedural duration was 95 (70-110) min, total fluoroscopy time 0.93 (0.40-1.73) min, and total fluoroscopy dose 35.4 (20.5-77.2) cGy cm2. Paced QRS duration (QRSd) was significantly shorter than intrinsic QRSd (121.9 +/- 10.7 vs. 159.2 +/- 34.4 ms; P < 0.001) and remained stable during the mean follow-up of 7.0 +/- 5.9 months. The LBBAP capture threshold was 0.57 +/- 0.23 V/0.4 ms at implantation and remained low during follow-up (0.58 +/- 0.18 V/0.5 +/- 0.2 ms; P = 0.877). Overall left ventricular ejection fraction improved significantly from 44.2 +/- 14.3% at baseline to 49.4 +/- 13.1% at follow-up (P = 0.009), New York Heart Association class from 2.4 +/- 0.6 to 1.8 +/- 0.6 (P = 0.002), respectively. No complications occurred that required intervention. Conclusion Routine near-zero fluoroscopy EAM-guided LBBAP can safely be performed in patients with SHD and advanced conduction abnormalities with high success rates and favourable mid-term outcomes. Further studies are needed to investigate whether the use of EAM improves the overall outcome of conduction system pacing and to identify specific patient populations who benefit the most from EAM-guided lead implantation.Cardiolog

Epidemiological situation of bovine brucellosis in the State of Rio Grande do Sul, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina. O Estado foi dividido em sete regiões. Em cada região foram amostradas aleatoriamente cerca de 300 propriedades, e dentro dessas foi escolhido de forma aleatória um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total foram amostrados 16.072 animais, provenientes de 1.957 propriedades. Em cada propriedade amostrada foi aplicado um questionário epidemiológico para verificar o tipo de exploração e as práticas zootécnicas e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e o reteste dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo se pelo menos um animal foi reagente às duas provas sorológicas. Para o Estado, as prevalências de focos e de animais infectados foram, respectivamente, 2,1% [1,5-2,6%] e 1,0% [0,60-1,4%]. Para os circuitos, a prevalência de focos e a de animais foram, respectivamente: circuito 1, 3,1% [1,4-5,7%] e 0,95% [0,0-2,0%]; circuito 2, 7,7% [4,9-11,3%] e 1,0% [0,40-1,7%]; circuito 3, 5,7% [3,4-8,8%] e 2,1% [0,41-3,8%]; circuito 4, 0,66% [0,08-2,4%] e 0,66% [0,0-1,8%]; circuito 5, 0,66% [0,08-2,4%] e 0,05% [0,0-0,13%]; circuito 6, 0,0% [0,0-1,3%] e 0,0% [0,0-0,25%]; circuito 7, 5,4% [2,5-10,1%] e 2,9% [0,49-5,3%]. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: exploração de corte (OR= 4,27 [1,82-10,01]) e histórico de aborto (OR=3,27,1,71-6,25]). ____________________________________________________________________________________________________________ ABSTRACTA study to characterize the epidemiological status of bovine brucellosis was carried out in the State of Rio Grande do Sul. The State was divided in seven regions. Three hundred herds were randomly sampled in each region and a pre-established number of animals were sampled in each of these herds. A total of 16,072 serum samples from 1,957 herds, were collected. In each herd, it was applied an epidemiological questionnaire focused on herd traits as well as husbandry and sanitary practices that could be associated with the risk of infection. The serum samples were screened for antibodies against Brucella spp. by the Rose-Bengal Test and all positive sera were re-tested by the 2-mercaptoethanol test. The herd was considered positive if at least one animal was positive on both tests. The prevalences of infected herds and animals in the State were, respectively 2.1% [1.5-2.6%] and 1.0% [0.60-1.4%]. In the regions, the prevalences of infected herds and animals were, respectively: region 1, 3.1% [1.4-5.7%] and 0.95% [0.0-2.0%]; region 2, 7.7% [4.9-11.3%] and 1.0% [0.40-1.7%]; region 3, 5.7% [3.4-8.8%] and 2.1% [0.41-3.8%]; region 4, 0.66% [0.08-2.4%] and 0.66% [0.0-1.8%]; region 5, 0.66% [0.08-2.4%] and 0.05% [0.0-0.13%]; region 6, 0.0% [0.0-1.3%] and 0.0% [0.0-0.25%]; and region 7, 5.4% [2.5-10.1%] and 2.9% [0.49-5.3%]. The risk factors (odds ratio, OR) associated with the presence of infection were: beef herd (OR= 4.27 [1.82-10.01]) and recent history of abortion (OR= 3.27-1.71-6.25])

Invariance of the Local Segmental Relaxation Dispersion in Polycyclohexylmethacrylate / Poly-alpha-Methylstyrene Blends

Dielectric spectroscopy was carried out on polycyclohexylmethacrylate (PCHMA) and its blend with poly-alpha-methylstyrene (PaMS) as a function of temperature and pressure. When measured at conditions whereby the local segmental relaxation time for the PCHMA was constant, the dispersion in the loss spectra had a fixed shape; that is, the relaxation time determines the breadth of the relaxation time distribution, independently of T and P. This result is known for neat materials and could be observed for the blend herein due to the nonpolar character of the PaMS and the degree of thermodynamic miscibility of the blend.Comment: 13 pages 5 figure

Global Search for New Physics with 2.0/fb at CDF

Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for "bumps" that could indicate resonant production of new particles; and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0/fb of ppbar collisions at sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D Rapid Communication