Lessons from the decoupling limit of Horava gravity

We consider the so-called "healthy" extension of Horava gravity in the limit where the Stuckelberg field decouples from the graviton. We verify the alleged strong coupling problem in this limit, under the assumption that no large dimensionless parameters are put in by hand. This follows from the fact that the dispersion relation for the Stuckelberg field does not have the desired z = 3 anisotropic scaling in the UV. To get the desired scaling and avoid strong coupling one has to introduce a low scale of Lorentz violation and retain some coupling between the graviton and the Stuckelberg field. We also make use of the foliation preserving symmetry to show how the Stuckelberg field couples to some violation of energy conservation. We source the Stuckelberg field using a point particle with a slowly varying mass and show that two such particles feel a constant attractive force. In this particular example, we see no Vainshtein effect, and violations of the Equivalence Principle. The latter is probably generic to other types of source and could potentially be used to place lower bounds on the scale of Lorentz violation.Comment: 18 pages, 1 figure. Version to appear in JHEP. Conclusions with respect to strong coupling modified - our strong coupling analysis does not apply to a low scale of Lorentz violation. Expanded Equivalence Principle violation discussion, noting it presents a challenge to low scale Lorentz violation, exactly the scenario designed to cure strong coupling. Other minor corrections and references adde

Changing alpha With Time: Implications For Fifth-Force-Type Experiments And Quintessence

If the recent observations suggesting a time variation of the fine structure constant are correct, they imply the existence of an ultra light scalar particle. This particle inevitably couples to nucleons through the \alpha-dependence of their masses and thus mediates an isotope-dependent long-range force. The strength of the coupling is within a couple of orders of magnitude from the existing experimental bounds for such forces. The new force can be potentially measured in the precision experimental tests of the equivalence principle. Due to an interesting coincidence of the required time-scales, the scalar filed in question can at the same time play the role of a quintessence field.Comment: 7 pages, Late

Unwinding of a cholesteric liquid crystal and bidirectional surface anchoring

We examine the influence of bidirectional anchoring on the unwinding of a planar cholesteric liquid crystal induced by the application of a magnetic field. We consider a liquid crystal layer confined between two plates with the helical axis perpendicular to the substrates. We fixed the director twist on one boundary and allow for bidirectional anchoring on the other by introducing a high-order surface potential. By minimizing the total free energy for the system, we investigate the untwisting of the cholesteric helix as the liquid crystal attempts to align with the magnetic field. The transitions between metastable states occur as a series of pitchjumps as the helix expels quarter or half-turn twists, depending on the relative sizes of the strength of the surface potential and the bidirectional anchoring. We show that secondary easy axis directions can play a significant role in the unwinding of the cholesteric in its transition towards a nematic, especially when the surface anchoring strength is large

New Upper Limit of Terrestrial Equivalence Principle Test for Rotating Extended Bodies

Improved terrestrial experiment to test the equivalence principle for rotating extended bodies is presented, and a new upper limit for the violation of the equivalence principle is obtained at the level of 1.6$10^{\text{-7}}$, which is limited by the friction of the rotating gyroscope. It means the spin-gravity interaction between the extended bodies has not been observed at this level.Comment: 4 page

Neutralization of (NK-cell-derived) B-cell activating factor by Belimumab restores sensitivity of chronic lymphoid leukemia cells to direct and Rituximab-induced NK lysis.

Natural killer (NK) cells are cytotoxic lymphocytes that substantially contribute to the therapeutic benefit of antitumor antibodies like Rituximab, a crucial component in the treatment of B-cell malignancies. In chronic lymphocytic leukemia (CLL), the ability of NK cells to lyse the malignant cells and to mediate antibody-dependent cellular cytotoxicity upon Fc receptor stimulation is compromised, but the underlying mechanisms are largely unclear. We report here that NK-cells activation-dependently produce the tumor necrosis factor family member 'B-cell activating factor' (BAFF) in soluble form with no detectable surface expression, also in response to Fc receptor triggering by therapeutic CD20-antibodies. BAFF in turn enhanced the metabolic activity of primary CLL cells and impaired direct and Rituximab-induced lysis of CLL cells without affecting NK reactivity per se. The neutralizing BAFF antibody Belimumab, which is approved for treatment of systemic lupus erythematosus, prevented the effects of BAFF on the metabolism of CLL cells and restored their susceptibility to direct and Rituximab-induced NK-cell killing in allogeneic and autologous experimental systems. Our findings unravel the involvement of BAFF in the resistance of CLL cells to NK-cell antitumor immunity and Rituximab treatment and point to a benefit of combinatory approaches employing BAFF-neutralizing drugs in B-cell malignancies

The Nab Experiment: A Precision Measurement of Unpolarized Neutron Beta Decay

Neutron beta decay is one of the most fundamental processes in nuclear physics and provides sensitive means to uncover the details of the weak interaction. Neutron beta decay can evaluate the ratio of axial-vector to vector coupling constants in the standard model, $\lambda = g_A / g_V$, through multiple decay correlations. The Nab experiment will carry out measurements of the electron-neutrino correlation parameter $a$ with a precision of $\delta a / a = 10^{-3}$ and the Fierz interference term $b$ to $\delta b = 3\times10^{-3}$ in unpolarized free neutron beta decay. These results, along with a more precise measurement of the neutron lifetime, aim to deliver an independent determination of the ratio $\lambda$ with a precision of $\delta \lambda / \lambda = 0.03\%$ that will allow an evaluation of $V_{ud}$ and sensitively test CKM unitarity, independent of nuclear models. Nab utilizes a novel, long asymmetric spectrometer that guides the decay electron and proton to two large area silicon detectors in order to precisely determine the electron energy and an estimation of the proton momentum from the proton time of flight. The Nab spectrometer is being commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source at Oak Ridge National Lab. We present an overview of the Nab experiment and recent updates on the spectrometer, analysis, and systematic effects.Comment: Presented at PPNS201

The fundamental constants and their variation: observational status and theoretical motivations

This article describes the various experimental bounds on the variation of the fundamental constants of nature. After a discussion on the role of fundamental constants, of their definition and link with metrology, the various constraints on the variation of the fine structure constant, the gravitational, weak and strong interactions couplings and the electron to proton mass ratio are reviewed. This review aims (1) to provide the basics of each measurement, (2) to show as clearly as possible why it constrains a given constant and (3) to point out the underlying hypotheses. Such an investigation is of importance to compare the different results, particularly in view of understanding the recent claims of the detections of a variation of the fine structure constant and of the electron to proton mass ratio in quasar absorption spectra. The theoretical models leading to the prediction of such variation are also reviewed, including Kaluza-Klein theories, string theories and other alternative theories and cosmological implications of these results are discussed. The links with the tests of general relativity are emphasized.Comment: 56 pages, l7 figures, submitted to Rev. Mod. Phy

Surgical management of mesh-related complications after prior pelvic floor reconstructive surgery with mesh

Contains fulltext : 96379.pdf (publisher's version ) (Closed access)INTRODUCTION AND HYPOTHESIS: The objective of this study is to evaluate the complications and anatomical and functional outcomes of the surgical treatment of mesh-related complications. METHODS: A retrospective cohort study of patients who underwent complete or partial mesh excision to treat complications after prior mesh-augmented pelvic floor reconstructive surgery was conducted. RESULTS: Seventy-three patients underwent 30 complete and 51 partial mesh excisions. Intraoperative complications occurred in 4 cases, postoperative complications in 13. Symptom relief was achieved in 92% of patients. Recurrence of pelvic organ prolapse (POP) occurred in 29% of complete and 5% of partial excisions of mesh used in POP surgery. De novo stress urinary incontinence (SUI) occurred in 36% of patients who underwent excision of a suburethral sling. CONCLUSIONS: Mesh excision relieves mesh-related complications effectively, although with a substantial risk of serious complications and recurrence of POP or SUI. More complex excisions should be performed in skilled centers

Trocar-guided total tension-free vaginal mesh repair of post-hysterectomy vaginal vault prolapse

Contains fulltext : 81076.pdf (publisher's version ) (Closed access)INTRODUCTION AND HYPOTHESIS: The objective of this study was to report 1 year anatomical and functional outcomes of trocar-guided total tension-free vaginal mesh (Prolift) repair for post-hysterectomy vaginal vault prolapse with one continuous piece of polypropylene mesh. METHODS: We conducted a prospective observational cohort study of 46 patients. A minimum sample size of 35 patients was needed to detect a recurrence rate of less than 20% at 12 months. Instruments of measurement used were pelvic organ prolapse quantification and validated questionnaires. RESULTS: Overall anatomical success was 91% (95% confidence interval 83-99), with significant improvement in experienced bother and quality of life. Mesh exposure occurred in seven patients (15%). No adverse effects on sexual function could be detected. CONCLUSIONS: Trocar-guided total tension-free vaginal mesh (Prolift) repair with one continuous piece of mesh for post-hysterectomy vaginal vault prolapse is well tolerated and anatomically and functionally highly effective. Results of controlled trials will determine its position in the operative armamentarium