110 research outputs found

    Quantum Radiation of Oscillons

    Full text link
    Many classical scalar field theories possess remarkable solutions: coherently oscillating, localized clumps, known as oscillons. In many cases, the decay rate of classical small amplitude oscillons is known to be exponentially suppressed and so they are extremely long lived. In this work we compute the decay rate of quantized oscillons. We find it to be a power law in the amplitude and couplings of the theory. Therefore, the quantum decay rate is very different to the classical decay rate and is often dominant. We show that essentially all oscillons eventually decay by producing outgoing radiation. In single field theories the outgoing radiation has typically linear growth, while if the oscillon is coupled to other bosons the outgoing radiation can have exponential growth. The latter is a form of parametric resonance: explosive energy transfer from a localized clump into daughter fields. This may lead to interesting phenomenology in the early universe. Our results are obtained from a perturbative analysis, a non-perturbative Floquet analysis, and numerics.Comment: 16 pages, 6 figures. V2: Expanded sections 1 and 2 plus other minor changes, added references. V3: Updated to resemble version published in Phys. Rev. D. V4: Slight rewording in 2nd paragrap

    On Inflation with Non-minimal Coupling

    Full text link
    A simple realization of inflation consists of adding the following operators to the Einstein-Hilbert action: (partial phi)^2, lambda phi^4, and xi phi^2 R, with xi a large non-minimal coupling. Recently there has been much discussion as to whether such theories make sense quantum mechanically and if the inflaton phi can also be the Standard Model Higgs. In this note we answer these questions. Firstly, for a single scalar phi, we show that the quantum field theory is well behaved in the pure gravity and kinetic sectors, since the quantum generated corrections are small. However, the theory likely breaks down at ~ m_pl / xi due to scattering provided by the self-interacting potential lambda phi^4. Secondly, we show that the theory changes for multiple scalars phi with non-minimal coupling xi phi dot phi R, since this introduces qualitatively new interactions which manifestly generate large quantum corrections even in the gravity and kinetic sectors, spoiling the theory for energies > m_pl / xi. Since the Higgs doublet of the Standard Model includes the Higgs boson and 3 Goldstone bosons, it falls into the latter category and therefore its validity is manifestly spoiled. We show that these conclusions hold in both the Jordan and Einstein frames and describe an intuitive analogy in the form of the pion Lagrangian. We also examine the recent claim that curvature-squared inflation models fail quantum mechanically. Our work appears to go beyond the recent discussions.Comment: 14 pages, 2 figures. Version 2: Clarified findings and improved wording. Elaborated important sections and removed an unnecessary section. Added references. Version 3: Updated towards JHEP version. Version 4: Final JHEP versio

    The Effective Field Theory of Cosmological Large Scale Structures

    Get PDF
    Large scale structure surveys will likely become the next leading cosmological probe. In our universe, matter perturbations are large on short distances and small at long scales, i.e. strongly coupled in the UV and weakly coupled in the IR. To make precise analytical predictions on large scales, we develop an effective field theory formulated in terms of an IR effective fluid characterized by several parameters, such as speed of sound and viscosity. These parameters, determined by the UV physics described by the Boltzmann equation, are measured from N-body simulations. We find that the speed of sound of the effective fluid is c_s^2 10^(-6) and that the viscosity contributions are of the same order. The fluid describes all the relevant physics at long scales k and permits a manifestly convergent perturbative expansion in the size of the matter perturbations \delta(k) for all the observables. As an example, we calculate the correction to the power spectrum at order \delta(k)^4. The predictions of the effective field theory are found to be in much better agreement with observation than standard cosmological perturbation theory, already reaching percent precision at this order up to a relatively short scale k \sim 0.24 h/Mpc.Comment: v2: typos corrected, JHEP published versio

    Fitness, motor competence and body composition as correlates of adolescent neck/shoulder pain: an exploratory cross-sectional study

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Adolescent neck/shoulder pain (NSP) is a common and sometimes debilitating problem. Several risk factors for this condition have been investigated, but no studies have previously evaluated associations between fitness, motor competence, body composition and adolescent NSP.</p> <p>Methods</p> <p>1608 males and females of mean age 14 years answered questions on their history of NSP (4 measures), and were tested for aerobic fitness, upper and lower limb power, trunk endurance, grip strength, shoulder flexibility, motor competence and anthropometric factors. Univariate and multivariate logistic regressions were used to test for associations between NSP and physical variables.</p> <p>Results</p> <p>There were significant gender differences for most physical and pain variables. After multivariate analysis, males had lower odds of NSP if they had reduced back endurance [OR: 0.66 (95% CI: 0.46–0.97)], reduced persistent control [0.42 (0.19–0.95], and increased muscle power [0.33 (0.12–0.94)], and higher odds of NSP if they had a higher basketball throw [2.47 (1.22–5.00)] and jump performance [3.47 (1.55–7.74)]. Females had lower odds for NSP if they had a reduced jump performance [0.61(0.41–0.92)], a better basketball throw [0.60(0.40–0.90)], lower shoulder flexibility [0.54 (0.30–0.98)] and a higher aerobic capacity [0.61 (0.40–0.93)], and higher odds for NSP if they had greater abdominal endurance [1.57(1.07–2.31)] and greater bimanual dexterity [1.77(1.18–2.65)]. Females showed a U shaped relationship between NSP and back endurance [low: 2.12 (1.20–3.74); high 2.12 (1.18–3.83)].</p> <p>Conclusion</p> <p>Adolescent NSP was associated with fitness and motor competence, although the associations varied with gender, and their strength was limited.</p

    Allogeneic Transplantation Provides Durable Remission in a Subset of DLBCL Patients Relapsing after Autologous Transplantation

    Get PDF
    For diffuse large B-cell lymphoma (DLBCL) patients progressing after autologous haematopoietic cell transplantation (autoHCT), allogeneic HCT (alloHCT) is often considered, although limited information is available to guide patient selection. Using the Center for International Blood and Marrow Transplant Research (CIBMTR) database, we identified 503 patients who underwent alloHCT after disease progression/relapse following a prior autoHCT. The 3-year probabilities of non-relapse mortality, progression/relapse, progression-free survival (PFS) and overall survival (OS) were 30, 38, 31 and 37% respectively. Factors associated with inferior PFS on multivariate analysis included Karnofsky performance status (KPS) <80, chemoresistance, autoHCT to alloHCT interval <1-year and myeloablative conditioning. Factors associated with worse OS on multivariate analysis included KPS<80, chemoresistance and myeloablative conditioning. Three adverse prognostic factors were used to construct a prognostic model for PFS, including KPS<80 (4 points), autoHCT to alloHCT interval <1-year (2 points) and chemoresistant disease at alloHCT (5 points). This CIBMTR prognostic model classified patients into four groups: low-risk (0 points), intermediate-risk (2-5 points), high-risk (6-9 points) or very high-risk (11 points), predicting 3-year PFS of 40, 32, 11 and 6%, respectively, with 3-year OS probabilities of 43, 39, 19 and 11% respectively. In conclusion, the CIBMTR prognostic model identifies a subgroup of DLBCL patients experiencing long-term survival with alloHCT after a failed prior autoHCT

    Allogeneic hematopoietic cell transplantation provides effective salvage despite refractory disease or failed prior autologous transplant in angioimmunoblastic T-cell lymphoma: a CIBMTR analysis

    Get PDF
    Abstract Background There is a paucity of data on the role of allogeneic hematopoietic cell transplantation (allo-HCT) in patients with angioimmunoblastic T-cell lymphoma (AITL). Using the CIBMTR registry, we report here the outcomes of AITL patients undergoing an allo-HCT. Methods We evaluated 249 adult AITL patients who received their first allo-HCT during 2000–2016. Results The median patient age was 56 years (range = 21–77). Majority of the patients were Caucasians (86%), with a male predominance (60%). Graft-versus-host disease (GVHD) prophylaxis was predominantly calcineurin inhibitor-based approaches while the most common graft source was peripheral blood (97%). Median follow-up of survivors was 49 months (range = 4–170 months). The cumulative incidence of grade 2–4 and grade 3–4 acute GVHD at day 180 were 36% (95% CI = 30–42) and 12 (95% CI = 8–17), respectively. The cumulative incidence of chronic GVHD at 1 year was 49% (95%CI 43–56). The 1-year non-relapse mortality (NRM) was 19% (95% CI = 14–24), while the 4-year relapse/progression, progression-free survival (PFS), and overall survival (OS) were 21% (95% CI = 16–27), 49% (95% CI = 42–56), and 56% (95% CI = 49–63), respectively. On multivariate analysis, chemoresistant status at the time of allo-HCT was associated with a significantly higher risk for therapy failure (inverse of PFS) (RR = 1.73 95% CI = 1.08–2.77), while KPS < 90% was associated with a significantly higher risk of mortality (inverse of OS) (RR = 3.46 95% CI = 1.75–6.87). Conclusion Our analysis shows that allo-HCT provides durable disease control even in AITL patients who failed a prior auto-HCT and in those subjects with refractory disease at the time of allografting.https://deepblue.lib.umich.edu/bitstream/2027.42/146782/1/13045_2018_Article_696.pd

    High-Content Chemical and RNAi Screens for Suppressors of Neurotoxicity in a Huntington's Disease Model

    Get PDF
    To identify Huntington's Disease therapeutics, we conducted high-content small molecule and RNAi suppressor screens using a Drosophila primary neural culture Huntingtin model. Drosophila primary neurons offer a sensitive readout for neurotoxicty, as their neurites develop dysmorphic features in the presence of mutant polyglutamine-expanded Huntingtin compared to nonpathogenic Huntingtin. By tracking the subcellular distribution of mRFP-tagged pathogenic Huntingtin and assaying neurite branch morphology via live-imaging, we identified suppressors that could reduce Huntingtin aggregation and/or prevent the formation of dystrophic neurites. The custom algorithms we used to quantify neurite morphologies in complex cultures provide a useful tool for future high-content screening approaches focused on neurodegenerative disease models. Compounds previously found to be effective aggregation inhibitors in mammalian systems were also effective in Drosophila primary cultures, suggesting translational capacity between these models. However, we did not observe a direct correlation between the ability of a compound or gene knockdown to suppress aggregate formation and its ability to rescue dysmorphic neurites. Only a subset of aggregation inhibitors could revert dysmorphic cellular profiles. We identified lkb1, an upstream kinase in the mTOR/Insulin pathway, and four novel drugs, Camptothecin, OH-Camptothecin, 18β-Glycyrrhetinic acid, and Carbenoxolone, that were strong suppressors of mutant Huntingtin-induced neurotoxicity. Huntingtin neurotoxicity suppressors identified through our screen also restored viability in an in vivo Drosophila Huntington's Disease model, making them attractive candidates for further therapeutic evaluation.National Institutes of Health (U.S.) (grant R01 EB007042)National Institutes of Health (U.S.
    corecore