928 research outputs found

    A new mechanism of mass protection for fermions

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    We present a way of protecting a Dirac fermion interacting with a scalar (Higgs) field from getting a mass from the vacuum. It is obtained through an implementation of translational symmetry when the theory is formulated with a momentum cutoff, which forbids the usual Yukawa term. We consider that this mechanism can help to understand the smallness of neutrino masses without a tuning of the Yukawa coupling. The prohibition of the Yukawa term for the neutrino forbids at the same time a gauge coupling between the right-handed electron and neutrino. We prove that this mechanism can be implemented on the lattice.Comment: LATTICE99(Higgs,Yukawa,SUSY), 3 page

    Symptoms in long-term breast cancer survivors:A cross-sectional study in primary care

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    Purpose: Various long-term symptoms can manifest after breast cancer treatment, but we wanted to clarify whether these are more frequent among long-term breast cancer survivors than matched controls and if they are associated with certain diagnoses. Methods: This was a cross-sectional, population-based study of 350 breast cancer survivors treated with chemo- and/or radiotherapy >= 5 years (median 10) after diagnosis and 350 women without cancer matched by age and primary care physician. All women completed a questionnaire enquiring about symptoms, underwent echocardiography to assess the left ventricle ejection fraction, and completed the Hospital Anxiety and Depression Scale. Cardiovascular diseases were diagnosed from primary care records. In a multivariable logistic regression analysis, symptoms were adjusted for the long-term effects and compared between cohorts and within the survivor group. Results: Concentration difficulties, forgetfulness, dizziness, and nocturia were more frequent among breast cancer survivors compared with controls, but differences could not be explained by cardiac dysfunction, cardiovascular diseases, depression, or anxiety. Intermittent claudication and appetite loss were more frequent among breast cancer survivors than controls and associated with cardiac dysfunction, depression, and anxiety. Breast cancer survivors treated with chemotherapy with/without radiotherapy were at significantly higher odds of forgetfulness and nocturia, but significantly lower odds of dizziness, compared with breast cancer survivors treated with radiotherapy alone. Conclusions: Intermittent claudication and appetite loss are common among breast cancer survivors and are associated with cardiac dysfunction and mood disorders. Other symptoms varied by whether the patient underwent chemotherapy with/without radiotherapy (forgetfulness and nocturia) radiotherapy alone (dizziness). (C) 2020 The Author(s). Published by Elsevier Ltd

    The risk of cutaneous squamous cell carcinoma among patients with type 2 diabetes receiving hydrochlorothiazide:A cohort study

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    Background: Because of continuous hyperglycemia and hyper-insulinemia and the use of photosensitizing drug, hydrochlorothiazide (HCTZ), the risk of cutaneous squamous cell carcinoma (cSCC) might be increased among patients with diabetes. This study aimed to estimate the risk of cSCC among HCTZ users with type 2 diabetes, and to determine whether thiazide-like diuretics, another drug in the same class with HCTZ, would be safer. Methods: We linked the benchmarking database in Dutch primary care, the Netherlands Cancer Registry, and the Dutch Personal Records Database (1998-2019). All 71,648 patients were included, except for those who had a history of skin cancer prior to cohort entry. We used Cox modeling to estimate the HRs and 95% confidence intervals for cSCC. The model was adjusted by cumulative exposure to each antihypertensive, age, sex, smoking, body mass index, blood pressure, serum creatinine, other confounding drug use at cohort entry, and cohort entry year. Results: There were 1,409 cSCC events (23 among thiazide-like diuretics users), during a follow-up of 679,789 person-years. Compared with no HCTZ use, the adjusted HRs for HCTZ use were 1.18 (1.00-1.40) for ≤2 years, 1.57 (1.32-1.88) for 2 to 4 years, and 2.09 (1.73-2.52) for >4 years. The HR was 0.90 (0.79-1.03) for an additional year of thiazide-like diuretic use. Conclusions: In patients with diabetes, exposure to HCTZ for >2 years is associated with an increased risk of cSCC, whereas no increased risk associated with thiazide-like diuretics was observed. Impact: The potential increased risk of cSCC should be a consideration when prescribing HCTZ, with thiazide-like diuretics offering a safer alternative

    Peculiarities of sub-barrier fusion with quantum diffusion approach

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    With the quantum diffusion approach the unexpected behavior of fusion cross section, angular momentum, and astrophysical S-factor at sub-barrier energies has been revealed. Out of the region of short-range nuclear interaction and action of friction at turning point the decrease rate of the cross section under the barrier becomes smaller. The calculated results for the reactions with spherical nuclei are in a good agreement with the existing experimental data.Comment: 11 pages, 5 figure

    Pattern formation in directional solidification under shear flow. I: Linear stability analysis and basic patterns

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    An asymptotic interface equation for directional solidification near the absolute stabiliy limit is extended by a nonlocal term describing a shear flow parallel to the interface. In the long-wave limit considered, the flow acts destabilizing on a planar interface. Moreover, linear stability analysis suggests that the morphology diagram is modified by the flow near the onset of the Mullins-Sekerka instability. Via numerical analysis, the bifurcation structure of the system is shown to change. Besides the known hexagonal cells, structures consisting of stripes arise. Due to its symmetry-breaking properties, the flow term induces a lateral drift of the whole pattern, once the instability has become active. The drift velocity is measured numerically and described analytically in the framework of a linear analysis. At large flow strength, the linear description breaks down, which is accompanied by a transition to flow-dominated morphologies, described in a companion paper. Small and intermediate flows lead to increased order in the lattice structure of the pattern, facilitating the elimination of defects. Locally oscillating structures appear closer to the instability threshold with flow than without.Comment: 20 pages, Latex, accepted for Physical Review

    Palaeontology, the biogeohistory of Victoria

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    The broad-scale distribution of fossils within Victoria is controlled by general global patterns in the biological evolution of life on Earth, the local development and environmental evolution of habitats, and the occurrence of geological processes conducive to the preservation of fossil floras and faunas. Early Palaeozoic fossils are mostly marine in origin because of the predominance of marine sedimentary rocks in Victoria and because life on land was not significant during most of this time interval. Middle Palaeozoic sequences have both terrestrial and marine fossil records. Within Victoria, marine rocks are only very minor components of strata deposited during the late Palaeozoic, so that few marine fossils are known from this time period. A similar situation existed during most of the Mesozoic except towards the end of this era when marine conditions began to prevail in the Bass Strait region. During long intervals in the Cainozoic, large areas of Victoria were flooded by shallow-marine seas, particularly in the southern basins of Bass Strait, as well as in the northwest of the State (Murray Basin). Cainozoic sediments contain an extraordinary range of animal and plant fossils. During the Quaternary, the landscape of Victoria became, and continues to be, dominated by continental environments including, at times, extensive freshwater lake systems. Fossil floras and faunas from sediments deposited in these lake systems and from other continental sediments, as well as from Quaternary sediments deposited in marginal marine environments, collectively record a history of rapid fluctuations in climate and sea level.<br /

    Resultant pressure distribution pattern along the basilar membrane in the spiral shaped cochlea

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    Cochlea is an important auditory organ in the inner ear. In most mammals, it is coiled as a spiral. Whether this specific shape influences hearing is still an open problem. By employing a three dimensional fluid model of the cochlea with an idealized geometry, the influence of the spiral geometry of the cochlea is examined. We obtain solutions of the model through a conformal transformation in a long-wave approximation. Our results show that the net pressure acting on the basilar membrane is not uniform along its spanwise direction. Also, it is shown that the location of the maximum of the spanwise pressure difference in the axial direction has a mode dependence. In the simplest pattern, the present result is consistent with the previous theory based on the WKB-like approximation [D. Manoussaki, Phys. Rev. Lett. 96, 088701(2006)]. In this mode, the pressure difference in the spanwise direction is a monotonic function of the distance from the apex and the normal velocity across the channel width is zero. Thus in the lowest order approximation, we can neglect the existance of the Reissner's membrane in the upper channel. However, higher responsive modes show different behavior and, thus, the real maximum is expected to be located not exactly at the apex, but at a position determined by the spiral geometry of the cochlea and the width of the cochlear duct. In these modes, the spanwise normal velocities are not zero. Thus, it indicates that one should take into account of the detailed geometry of the cochlear duct for a more quantitative result. The present result clearly demonstrates that not only the spiral geometry, but also the geometry of the cochlear duct play decisive roles in distributing the wave energy.Comment: 21 pages. (to appear in J. Biol. Phys.

    Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System

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    We present a series of measurements based on K -> pi+pi- and K -> pi0pi0 decays collected in 1996-1997 by the KTeV experiment (E832) at Fermilab. We compare these four K -> pipi decay rates to measure the direct CP violation parameter Re(e'/e) = (20.7 +- 2.8) x 10^-4. We also test CPT symmetry by measuring the relative phase between the CP violating and CP conserving decay amplitudes for K->pi+pi- (phi+-) and for K -> pi0pi0 (phi00). We find the difference between the relative phases to be Delta-phi = phi00 - phi+- = (+0.39 +- 0.50) degrees and the deviation of phi+- from the superweak phase to be phi+- - phi_SW =(+0.61 +- 1.19) degrees; both results are consistent with CPT symmetry. In addition, we present new measurements of the KL-KS mass difference and KS lifetime: Delta-m = (5261 +- 15) x 10^6 hbar/s and tauS = (89.65 +- 0.07) x 10^-12 s.Comment: Submitted to Phys. Rev. D, August 6, 2002; 37 pages, 32 figure

    Carrier relaxation, pseudogap, and superconducting gap in high-Tc cuprates: A Raman scattering study

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    We describe results of electronic Raman-scattering experiments in differently doped single crystals of Y-123 and Bi-2212. The comparison of AF insulating and metallic samples suggests that at least the low-energy part of the spectra originates predominantly from excitations of free carriers. We therefore propose an analysis of the data in terms of a memory function approach. Dynamical scattering rates and mass-enhancement factors for the carriers are obtained. In B2g symmetry the Raman data compare well to the results obtained from ordinary and optical transport. For underdoped materials the dc scattering rates in B1g symmetry become temperature independent and considerably larger than in B2g symmetry. This increasing anisotropy is accompanied by a loss of spectral weight in B2g symmetry in the range between the superconducting transition at Tc and a characteristic temperature T* of order room temperature which compares well with the pseudogap temperature found in other experiments. The energy range affected by the pseudogap is doping and temperature independent. The integrated spectral loss is approximately 25% in underdoped samples and becomes much weaker towards higher carrier concentration. In underdoped samples, superconductivity related features in the spectra can be observed only in B2g symmetry. The peak frequencies scale with Tc. We do not find a direct relation between the pseudogap and the superconducting gap.Comment: RevTeX, 21 pages, 24 gif figures. For PostScript with embedded eps figures, see http://www.wmi.badw-muenchen.de/~opel/k2.htm
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