Small Asymmetry Research Articles

The LBNE near detector

The Long-Baseline Neutrino Experiment (LBNE) is a next generation neutrino oscillation experiment currently proposed for construction in the United States with the main goal of studying muon (anti)neutrinos oscillations into electron (anti)neutrinos over a distance greater than 1000 km and over a wide range of neutrino energies. Its main physics results will be the precision measurement of δCP and all three mixing angles. A value of δCP different from 0 or π will appear in the LBNE data as a small (0% to 40%) asymmetry on the oscillation probability of neutrinos versus antineutrinos. Such a small effect requires a very good control of the systematic uncertainties affecting the measurement and this can only been accomplished using a near detector. I will describe the LBNE near detector complex focusing primarily on its reference design, which includes a set of muon detectors to monitor the beam and a magnetized liquid argon TPC surrounded by a muon identifier detector to measure neutrino interactions at the near site.

Enxerto composto auricular na reconstrução da asa nasal

Since the nose is located in the center of the face, small asymmetries and imperfections are easily recognized. One subunit of the nose is the nasal ala, a region that, when reconstructed, requires the achievement of esthetic and functional results. This poses a challenge to the plastic surgeon. In this article, we describe 3 cases of composite auricular grafts used for nasal alar reconstruction. The grafts presented total integration and provided satisfactory esthetic and functional results. A literature review revealed no differences in the complication rates between grafts and local flaps. Moreover, the shape of the auricular cartilage was maintained over time, showing rare distortions and no or minimal absorption, contrary to costal cartilage and bone grafts. The use of composite auricular grafts is versatile and safe. This procedure ensures excellent results in nasal alar reconstruction and guarantees low morbidity within the donor areas. Therefore, the use of this technique efficiently enables the repair of nasal defects.

Collider-Independenttt¯Forward-Backward Asymmetries

We introduce the forward-backward asymmetries A(u), A(d) corresponding to uū, dd → tt production, respectively, at hadron colliders. These are collider and center-of-mass independent observables, directly related to the forward-backward and charge asymmetries measured at the Tevatron and the LHC, respectively. We discuss how to extract these asymmetries from data. Because these asymmetries are collider independent, their measurement at these two colliders could elucidate the nature of the anomalous forward-backward asymmetry measured at the Tevatron. Our framework also shows in a model independent fashion that a positive Tevatron asymmetry exceeding the standard model expectation is compatible with the small asymmetry measured at the LHC.

Dynamics and control of dual-spin gyrostat spacecraft with changing structure

We study the motion of the free dual-spin gyrostat spacecraft that consists of the platform with a triaxial ellipsoid of inertia and the rotor with a small asymmetry with respect to the axis of rotation. The system with perturbations caused by a small asymmetry of the rotor and the time-varying moments of inertia of the rotor is considered. The dimensionless equations of the system are written in Serret-Andoyer canonical variables. The system's phase space is described. It is shown that changes in the moments of inertia of the gyrostat leads to the deformation of the phase space. The internal torque control law is proposed that keeps the system at the center point in the phase space. The effectiveness of the control is shown through a numerical simulation. It's shown that the uncontrolled gyrostat can lose its axis orientation. Proposed internal torque keeps the initial angle between the axis of the gyrostat and the total angular momentum vector.

BVRI photometric and polarimetric studies of W UMa type eclipsing binary FO Hydra

We present analysis of optical photometric and polarimetric observations of contact binary system FO Hydra (FO Hya). The computed period of the system is 0.469556±0.000003days. An O–C curve analysis indicates an increase in its period by 5.77×10−8dayyr−1. The photometric light curves are analyzed using Wilson–Devinney code (WD). The present analysis shows that FO Hya is a B-subtype of W UMa type contact binary. The radii and mass of primary and secondary components are found, respectively, to be R1=1.62±0.03 R⊙ and R2=0.91±0.02 R⊙, and M1=1.31±0.07M⊙ and M2=0.31±0.11M⊙. The light curve shape shows small asymmetries around the primary and secondary maxima. This may be due to the presence of dark spots on the components. The polarimetric observations yield average values of its polarization to be 0.18±0.03, 0.15±0.03, 0.17±0.02 and 0.15±0.02% in B, V, R and I bands, respectively. These values are appreciably lower than the typical polarization of W UMa type binaries. We have discussed the possible sources of the observed polarization but in order to arrive at definitive answer to this more phase locked observations are needed.

Preferentially directed flux motion in a very thin superconducting strip with nanostructured profile

We report an experimental and numerical study of the vortex matter moving in a very thin type II superconducting strip with asymmetrically nanostructured profile. The asymmetric thickness profile generates a geometrical force landscape that sets a preferential direction for vortex motion, resulting in an uncommon voltage-current curve of the strip, with vanishingly small asymmetry in the positive and negative critical currents but appreciably large asymmetry in the voltages. Experimental results as well as the geometrical force affecting the moving vortex matter are discussed in the framework of time dependent Ginzburg-Landau model for superconductors with variable thickness.

Instability of a general rotating system with small axial asymmetry and damping

The paper presents new results on instability of general rotating systems with small axial asymmetry and damping. Rotating systems with arbitrary finite degrees of freedom are considered. Instability conditions are derived for nonresonant and resonant rotation speeds characterized by simple and double eigenvalues. As an application, the stability problem of a rotating elastic shaft with small internal and external damping forces and asymmetric imperfections is studied. The numerical example shows validity and accuracy of the derived analytical formulae for the instability regions.

An explanation of phase deformation tension–compression asymmetry of TiNi by means of microstructural modeling

Abstract Phase deformation of mono- and polycrystalline TiNi specimens due to the direct martensitic transformation is simulated by means of a microstructural model. These simulations show that the deformation of a polycrystalline specimen loaded by a constant stress and cooled down across the temperature interval of the direct martensitic transformation depends on the mode of the stress being much less in the case of compression than in the case of tension. For most orientations of a single crystal modeling predicts a positive tension–compression asymmetry: the phase deformation in tension dominates over that in compression. Only for few orientations a small negative asymmetry is observed. A hypothesis is suggested that the positive tension–compression asymmetry of the phase deformation is inherent to TiNi because of the specific value of the third invariant of the Bain's deformation tensor. This hypothesis explaining the experimentally observed tension–compression asymmetry of untextured TiNi polycrystals is supported by microstructural modeling. Modeling also shows how the texture when it exists affects the phase deformation. By varying only the third invariant of the Bain's deformation tensor one can construct a model material either having no tension–compression asymmetry or having a negative asymmetry when the strain in tension is less than that in compression.

Persistent layer‐by‐layer growth for pulsed‐laser homoepitaxy of $(000\bar 1)$ ZnO

AbstractPersistent layer‐by‐layer growth is demonstrated for pulsed‐laser homoepitaxy of ZnO thin films on $(000\bar 1)$ ZnO single crystals. Employing interval pulsed‐laser deposition (PLD), RHEED oscillations are stabilized over a film thickness of about 90 nm. For interval pulsed laser deposited films a considerably decreased root‐mean‐square surface roughness of 0.26 nm was found, in comparison to 0.74 nm for conventional PLD. A small asymmetry in the X‐ray diffraction (XRD) 2θ –ω scan reveals compressive strain in the thin film being slightly larger for interval PLD as compared to conventional PLD. The FWHM of the photoluminescence (PL) I6 line is higher with about 500 µeV as compared to 350 µeV for the conventional PLD. Consequently, both XRD as well as PL indicate a slightly higher amount of charged defects for the interval PLD.magnified imageEvolution of RHEED intensity as function of time for interval PLD. The green and red line marks the start and the end of the ablation interval, respectively.(© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Square-wave oscillations in semiconductor ring lasers with delayed optical feedback

We analyze experimentally and theoretically the effects of delayed optical cross-feedback in semiconductor ring lasers. We show that under appropriate conditions, feeding of only one directional mode back into the counter-propagating mode leads to square-wave oscillations. In this regime, the laser switches regularly between the two counter-propagating modes with a period close to twice the roundtrip time in the external feedback loop. We find that these oscillations are robust and appear for a wide range of parameters as long as a small asymmetry in the linear coupling between both modes is present. We show that by increasing the feedback strength or the injection current, the square-wave oscillations gradually disappear. Due to noise, mode-hopping between stable lasing in one directional mode and square wave oscillations is observed in this transition region.

Solidification in syntectic and monotectic systems

We present theoretical studies of syntectic and monotectic solidification scenarios. Steady-state solidification along the liquid-liquid interface in a syntectic system is considered by means of a boundary-integral technique developed previously. We study the case of small asymmetry of the pattern and extract from the results the scaling relations in terms of the undercooling and the asymmetry parameter. We also investigate monotectic solidification using the phase-field method. We present two kinds of two-phase fingers, with the solid phase being either the exterior phase or the interior phase, and the pattern corresponding to the growth along the solid-liquid interface. We finally analyze the asymptotic shape of these new morphologies far behind their tip.

Dynamics and chaos control of gyrostat satellite

We consider the chaotic motion of the free gyrostat consisting of a platform with a triaxial inertia ellipsoid and a rotor with a small asymmetry with respect to the axis of rotation. Dimensionless equations of motion of the system with perturbations caused by small asymmetries of the rotor are written in Andoyer-Deprit variables. These perturbations lead to separatrix chaos. For gyrostats with different ratios of moments of inertia heteroclinic and homoclinic trajectories are written in closed-form. These trajectories are used for constructing modified Melnikov function, which is used for determine the control that eliminates separatrix chaos. Melnikov function and phase space trajectory are built to show the effectiveness of the control.

A Selection Principle for the Sharp Quantitative Isoperimetric Inequality

We introduce a new variational method for the study of isoperimetric inequalities with quantitative terms. The method is general as it relies on a penalization technique combined with the regularity theory for quasiminimizers of the perimeter. Two notable applications are presented. First we give a new proof of the sharp quantitative isoperimetric inequality in \({\mathbb{R}^n}\). Second we positively answer a conjecture by Hall concerning the best constant for the quantitative isoperimetric inequality in \({\mathbb{R}^2}\) in the small asymmetry regime.

Thermalisation of light sterile neutrinos in the early universe

Recent cosmological data favour additional relativistic degrees of freedom beyond the three active neutrinos and photons, often referred to as ``dark'' radiation. Light sterile neutrinos is one of the prime candidates for such additional radiation. However, constraints on sterile neutrinos based on the current cosmological data have been derived using simplified assumptions about thermalisation of νs at the Big Bang Nucleosynthesis (BBN) epoch. These assumptions are not necessarily justified and here we solve the full quantum kinetic equations in the (1 active + 1 sterile) scenario and derive the number of thermalised species just before BBN begins (T ≃ 1 MeV) for null (L = 0) and large (L = 10−2) initial lepton asymmetry and for a range of possible mass-mixing parameters. We find that the full thermalisation assumption during the BBN epoch is justified for initial small lepton asymmetry only. Partial or null thermalisation occurs when the initial lepton asymmetry is large.

Post-equinox dynamics and polar cloud structure on Uranus

Post equinox imaging of Uranus by HST, Keck, and Gemini telescopes has enabled new measurements of winds over previously sampled latitudes as well as measurements at high northern latitudes that have recently come into better view. These new observations also used techniques to greatly improve signal to noise ratios, making possible the detection and tracking of more subtle cloud features. The 250m/s prograde jet peaking near 60°N was confirmed and more accurately characterized. Several long-lived cloud features have also been tracked. The winds pole-ward of 60°N are consistent with solid body rotation at a westward (prograde) rate of 4.3°/h with respect to Uranus’ interior. When combined with 2007 and other recent measurements, it is clear that a small but well-resolved asymmetry exists in the zonal profile at middle latitudes, peaking at 35°, where southern winds are 20m/s more westward than corresponding northern winds. High S/N Keck II imaging of the north polar region of Uranus reveals a transition from streaky bands below 60°N to a region from 60° to nearly the north pole, where widely distributed small bright spots, resembling cumulus cloud fields, with several isolated dark spots, are the dominant style of cloud features. This presents a stark contrast to 2003 detailed views of the south polar region of Uranus when no discrete cloud features could be detected in comparable Keck II near-IR images. The pressure levels of discrete clouds estimated from spatial modulations in H and Hcont images indicate that the polar cloud features are generally in the 1.3 to 2–3bar range, as are equatorial and several mid-latitude features. Several of the brighter mid latitude features are found above the 1.2-bar level of methane condensation.

SU-E-T-533: Evaluating Effective Source Position Corrections during Modeling with Pinnacle Version 9.2 Software for Flattening Free (FFF) Small Field Treatments.

Advanced treatment delivery techniques require more robust treatment planning system (TPS) models for accurate dose planning and computation. As stereotactic body radiation therapy (SBRT) and volumetric-modulated arc therapy (VMAT) treatments become more prevalent, the ability of the TPS to accurately calculate dose delivered from small fields becomes of greater importance. An additional level of complexity in photon beam modeling is added with the inclusion of flattening filter free (FFF) treatment beams, due to steep in field dose gradients and non uniform penumbra regions. The purpose of this work is to examine the ability of ADAC/Pinnacle TPS to accurately model and calculate dose from small field FFF treatment beams. Photon beam data was first modeled using Pinnacle v9.0. Flattened and FFF beam models were generated for 6MV and 10MV energies. Models were fine-tuned using a 5×5 cm2 field as the standard field in order to place more emphasis on the accuracy of the model for the small fields. An upgrade to Pinnacle v9.2 allowed for comparison between version 9.0 and version 9.2. Accurately modeling small fields using Pinnacle v9.0 proved difficult, particularly in the lower penumbra region. An asymmetry appeared in the small field models for both the flattened and FFF models. The Pinnacle v9.2 upgrade eliminated the small field asymmetries, and allowed for more accurate penumbra region calculations. Preliminary results have shown that Pinnacle v9.2 is capable of developing accurate beam models when an emphasis is placed on the small fields. In addition, patient specific dosimetric information for version 9.0 and version 9.2 was also calculated and examined for prostate, head & neck, and lung treatments. Pinnacle v9.2 showed improved accuracy in small field FFF dose modeling over version 9.0. Comparison of patient dosimetric information reflected the improvement in the small field modeling.

BBN with electron-sterile neutrino oscillations — the finest leptometer

A relic lepton asymmetry orders of magnitude bigger than the baryon one may hide in the relic neutrino background. No direct theoretical or experimental limitations on its magnitude and sign are known. Only indirect cosmological constraints exist ranging from |L| < 0.01 to L < 10. Here we discuss a Big Bang Nucleosynthesis (BBN) model with late electron-sterile neutrino oscillations. The influence of L on neutrino oscillations and on nucleons freezing in the pre-BBN epoch is numerically analyzed in the full range of the oscillation parameters of the model and for |L| ⩾ 10−10. The asymmetry-oscillations interplay is studied in detail and the behavior of L for different oscillation parameters is found. L effect on the primordially produced 4He is precisely studied. It is shown that this BBN model is a fine leptometer, capable of feeling extremely small relic lepton asymmetry — |L| > 10−8. The case of oscillations generated asymmetry by late electron-sterile oscillations and its effect on the primordial 4He is also briefly discussed. The instability region of the asymmetry growth is obtained.

Asymmetric marginal costs in search models

I show that marginal cost asymmetry has important implications for search models. In several widely used search models with mixed strategy equilibria, excluding some special cases, firms with different marginal costs cannot randomize prices in the same interval. So, even a small asymmetry in marginal costs may result in a drastic asymmetry in equilibrium prices.

Warm baryogenesis

We show that a baryon asymmetry can be generated by dissipative effects during warm inflation via a supersymmetric two-stage mechanism, where the inflaton is coupled to heavy mediator fields that then decay into light species through B- and CP-violating interactions. In contrast with thermal GUT baryogenesis models, the temperature during inflation is always below the heavy mass threshold, simultaneously suppressing thermal and quantum corrections to the inflaton potential and the production of dangerous GUT relics. This naturally gives a small baryon asymmetry close to the observed value, although parametrically larger values may be diluted after inflation along with any gravitino overabundance. Furthermore, this process yields baryon isocurvature perturbations within the range of future experiments, making this an attractive and testable model of GUT baryogenesis.

Transverse spin effects in hadron-pair production from semi-inclusive deep inelastic scattering

First measurements of azimuthal asymmetries in hadron-pair production in deep-inelastic scattering of muons on transversely polarised LiD6 (deuteron) and NH3 (proton) targets are presented. The data were taken in the years 2002–2004 and 2007 with the COMPASS spectrometer using a muon beam of 160 GeV/c at the CERN SPS. The asymmetries provide access to the transversity distribution functions, without involving the Collins effect as in single hadron production. The sizeable asymmetries measured on the NH3 target indicate non-vanishing u-quark transversity and two-hadron interference fragmentation functions. The small asymmetries measured on the LiD6 target can be interpreted as indication for a cancellation of u- and d-quark transversities.