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Sridhar Yaddanapudi, Bin Cai, Taylor Harry, Steven Dolly, Baozhou Sun, Hua Li, Keith Stinson, Camille Noel, Lakshmi Santanam, Todd Pawlicki, Sasa Mutic, S Murty Goddu
PURPOSE: The purpose of this study was to develop a novel process for using on-board MV and kV Electronic Portal Imaging Devices (EPIDs) to perform linac acceptance testing (AT) for two reasons: 1) to standardize the assessment of new equipment performance, and 2) to reduce the time to clinical use while reducing physicist workload. METHODS AND MATERIALS: In this study, Varian TrueBeam linacs equipped with amorphous silicon based EPID (aS1000) were used. The conventional set of AT tests and tolerances were used as a baseline guide...
April 22, 2017: Medical Physics
A Stesmans, S Iacovo, D Chiappe, I Radu, C Huyghebaert, S De Gendt, V V Afanas'ev
A low-temperature electron spin resonance study has been carried out on large-area high-purity polycrystalline two-dimensional few monolayer (ML) 2H MoS2 films synthesized by sulfurization of Mo layers, with intent to atomically assess mobility-degrading detrimental point defects. This reveals the presence of a distinct previously unreported anisotropic defect of axial symmetry about the c-axis characterized by g // = 2.00145 and g ⊥ = 2.0027, with corresponding density (spin S = ½) ~3 × 10(12) cm(-2) for a 4 ML thick film...
December 2017: Nanoscale Research Letters
Janneke Hilderink, Marleen C Tjepkema-Cloostermans, Anita Geertsema, Janita Glastra-Zwiers, Cecile C de Vos
PURPOSE: Vagus nerve stimulation (VNS) has shown to be an effective treatment for drug resistant epilepsy, with achieving more than 50% seizure reduction in one third of the treated patients. In order to predict which patients will profit from VNS, we previously found that a low pairwise derived Brain Symmetry Index (pdBSI) could potentially predict good responders to VNS treatment. These findings however have to be validated before they can be generalized. METHODS: 39 patients (age 18-68 years) with medically intractable epilepsy who were referred for an implanted VNS system were included...
April 4, 2017: Seizure: the Journal of the British Epilepsy Association
Ya Xiao, Xiang-Jun Ye, Kai Sun, Jin-Shi Xu, Chuan-Feng Li, Guang-Can Guo
Einstein-Podolsky-Rosen (EPR) steering describes the ability of one party to remotely affect another's state through local measurements. One of the most distinguishable properties of EPR steering is its asymmetric aspect. Steering can work in one direction but fail in the opposite direction. This type of one-way steering, which is different from the symmetry concepts of entanglement and Bell nonlocality, has garnered much interest. However, an experimental demonstration of genuine one-way EPR steering in the simplest scenario, i...
April 7, 2017: Physical Review Letters
Tsuneya Yoshida, Akito Daido, Youichi Yanase, Norio Kawakami
In this paper, we propose CeCoIn_{5}/YbCoIn_{5} superlattice systems as a test bed for the reduction of topological classification in free fermions. We find that the system with a quadlayer of CeCoIn_{5} shows a topological crystalline superconducting phase with the mirror Chern number eight at the noninteracting level. Furthermore, we demonstrate that in the presence of two-body interactions, gapless edge modes are no longer protected by the symmetry in the system with a quadlayer, but are protected in the system with a bilayer or trilayer...
April 7, 2017: Physical Review Letters
V V Flambaum, M V Romalis
Anisotropy in the speed of light that has been constrained by Michelson-Morley-type experiments also generates anisotropy in the Coulomb interactions. This anisotropy can manifest itself as an energy anisotropy in nuclear and atomic experiments. Here the experimental limits on Lorentz violation in _{10}^{21}Ne are used to improve the limits on Lorentz symmetry violations in the photon sector, namely, the anisotropy of the speed of light and the Coulomb interactions, by 7 orders of magnitude in comparison with previous experiments: the speed of light is isotropic to a part in 10^{28}...
April 7, 2017: Physical Review Letters
Ioan B Magdău, Graeme J Ackland
We show that the isotope effect leads to a completely different spectroscopic signal in hydrogen-deuterium mixtures, compared to pure elements that have the same crystal structure. This is particularly true for molecular vibrations, which are the main source of information about the structure of high-pressure hydrogen. Mass disorder breaks translational symmetry, meaning that vibrations are localized almost to single molecules, and are not zone-center phonons. In mixtures, each observable infrared (IR) peak corresponds to a collection of many such molecular vibrations, which have a distribution of frequencies depending on local environment...
April 7, 2017: Physical Review Letters
Yan Qi Qin, B Normand, Anders W Sandvik, Zi Yang Meng
The amplitude ("Higgs") mode is a ubiquitous collective excitation related to spontaneous breaking of a continuous symmetry. We combine quantum Monte Carlo (QMC) simulations with stochastic analytic continuation to investigate the dynamics of the amplitude mode in a three-dimensional dimerized quantum spin system. We characterize this mode by calculating the spin and dimer spectral functions on both sides of the quantum critical point, finding that both the energies and the intrinsic widths of the excitations satisfy field-theoretical scaling predictions...
April 7, 2017: Physical Review Letters
Niklas Beisert, Aleksander Garus, Matteo Rosso
In this Letter, we establish Yangian symmetry of planar N=4 supersymmetric Yang-Mills theory. We prove that the classical equations of motion of the model close onto themselves under the action of Yangian generators. Moreover, we propose an off-shell extension of our statement, which is equivalent to the invariance of the action and prove that it is exactly satisfied. We assert that our relationship serves as a criterion for integrability in planar gauge theories by explicitly checking that it applies to the integrable Aharony-Bergman-Jafferis-Maldacena theory but not to the nonintegrable N=1 supersymmetric Yang-Mills theory...
April 7, 2017: Physical Review Letters
Srinidhi T Ramamurthy, Yuxuan Wang, Taylor L Hughes
Topological crystalline insulators are a new class of materials that have metallic surface states on select surfaces due to point group crystalline symmetries. In this Letter, we consider a model for a three-dimensional topological crystalline insulator with Dirac nodes occurring on a surface that are protected by the mirror symmetry. We demonstrate that the electromagnetic response for such a system is characterized by a 1-form b_{μ}. The value of b_{μ} can be inferred from the locations of the surface Dirac nodes in energy-momentum space...
April 7, 2017: Physical Review Letters
Markus Berger, Marcus Bauser, Thomas Frenzel, Christoph Stephan Hilger, Gregor Jost, Silvia Lauria, Bernd Morgenstern, Christian Neis, Hubertus Pietsch, Detlev Sülzle, Kaspar Hegetschweiler
Heavy-metal-based contrast agents (CAs) offer enhanced X-ray absorption for X-ray computed tomography (CT) compared to the currently used iodinated CAs. We report the discovery of new lanthanide and hafnium azainositol complexes and their optimization with respect to high water solubility and stability. Our efforts culminated in the synthesis of BAY-576, an uncharged hafnium complex with 3:2 stoichiometry and broken complex symmetry. The superior properties of this asymmetrically substituted hafnium CA were demonstrated by a CT angiography study in rabbits that revealed excellent signal contrast enhancement...
April 21, 2017: Inorganic Chemistry
Shuang Zhou, Sergij V Shiyanovskii, Heung-Shik Park, Oleg D Lavrentovich
The detailed structure of singularities of ordered field represents a fundamental problem in diverse areas of physics. At the defect cores, the deformations are so strong that the system explores states with symmetry different from that of an undistorted material. These regions are difficult to explore experimentally as their spatial extension is very small, a few molecular lengths in the condensed matter. Here we explore the cores of disclinations in the so-called chromonic nematics that extend over macroscopic length scales accessible for optical characterization...
April 21, 2017: Nature Communications
Markus Eschbach, Martin Lanius, Chengwang Niu, Ewa Młyńczak, Pika Gospodarič, Jens Kellner, Peter Schüffelgen, Mathias Gehlmann, Sven Döring, Elmar Neumann, Martina Luysberg, Gregor Mussler, Lukasz Plucinski, Markus Morgenstern, Detlev Grützmacher, Gustav Bihlmayer, Stefan Blügel, Claus M Schneider
New three-dimensional (3D) topological phases can emerge in superlattices containing constituents of known two-dimensional topologies. Here we demonstrate that stoichiometric Bi1Te1, which is a natural superlattice of alternating two Bi2Te3 quintuple layers and one Bi bilayer, is a dual 3D topological insulator where a weak topological insulator phase and topological crystalline insulator phase appear simultaneously. By density functional theory, we find indices (0;001) and a non-zero mirror Chern number. We have synthesized Bi1Te1 by molecular beam epitaxy and found evidence for its topological crystalline and weak topological character by spin- and angle-resolved photoemission spectroscopy...
April 21, 2017: Nature Communications
Xiaohua Zhou, Erhu Zhang, Minggang Xia, Lei Zhang, Zhiqi Tian, Jianlin Liu, Shengli Zhang
Gaining insight into the relationships between the self-organized cell structures and the properties of biotissues is helpful for revealing the function of biomaterials and its designing principle. However, the traditionally used random foam model neglects several important details of the frameworks of cell clusters resulting in incomplete conclusions. Herein, we use a more complete model, the cell adhesion model, to investigate the mechanical and morphological properties of the two-dimensional (2D) dry cell foams...
April 21, 2017: Physical Chemistry Chemical Physics: PCCP
Hiroyuki Watanabe, Masataka Hirose, Kazuo Tanaka, Yoshiki Chujo
This communication describes the transformation of a non-emissive heterocycle into a luminophore via modulation of molecular orbitals by employing a dialkylamine-substituted pentaazaphenalene (A5AP) skeleton. It was presumed that the introduction of the amine group changed the symmetry-forbidden HOMO-LUMO (H-L) transition to an allowed one. According to optical measurements and theoretical calculations, the H-L transition was turned into the symmetry-allowed one because of the lone pair on the nitrogen atom in the dialkylamine substituent...
April 21, 2017: Chemical Communications: Chem Comm
J W Harter, Z Y Zhao, J-Q Yan, D G Mandrus, D Hsieh
Strong electron interactions can drive metallic systems toward a variety of well-known symmetry-broken phases, but the instabilities of correlated metals with strong spin-orbit coupling have only recently begun to be explored. We uncovered a multipolar nematic phase of matter in the metallic pyrochlore Cd2Re2O7 using spatially resolved second-harmonic optical anisotropy measurements. Like previously discovered electronic nematic phases, this multipolar phase spontaneously breaks rotational symmetry while preserving translational invariance...
April 21, 2017: Science
Jelena Stajic
No abstract text is available yet for this article.
April 21, 2017: Science
Alli Gokeler, Wouter Welling, Anne Benjaminse, Koen Lemmink, Romain Seil, Stefano Zaffagnini
BACKGROUND: Hop tests are frequently used to determine return to sports (RTS) after anterior cruciate ligament reconstruction (ACLR). Given that bilateral deficits are present after ACLR, this may result in a falsely high limb symmetry index (LSI), since LSI is calculated as a ratio between the values of the limbs. HYPOTHESIS: Athletes after ACLR would achieve LSI > 90% for the hop test. Secondly, athletes after ACLR demonstrate decreased jump distance on the single hop for distance (SLH) and triple leg hop for distance (TLH) and decreased number of hops for the side hop (SH) for both involved and uninvolved limbs compared to normative data of sex, age and type of sports matched healthy athletes...
April 17, 2017: Orthopaedics & Traumatology, Surgery & Research: OTSR
Kelvin J Murray, Tom Molyneux, Michael R Le Grande, Aurora Castro Mendez, Franz K Fuss, Michael F Azari
OBJECTIVE: The purpose of this study was to evaluate the correlation between mild leg length discrepancy (LLD) and degenerative joint disease (DJD) or osteoarthritis. METHODS: We evaluated standard postural lumbopelvic radiographs from 255 adults (121 women and 134 men) who had presented with spinal pain for chiropractic care. Symmetry of femoral head diameters was used to exclude magnification errors. Pearson's partial correlation was used to control for age and derive effect sizes for LLD on DJD in the hip and lower lumbar motion segments...
April 17, 2017: Journal of Manipulative and Physiological Therapeutics
Irena Dujmovic, Sasa Radovanovic, Vanja Martinovic, Jelena Dackovic, Gorica Maric, Sarlota Mesaros, Tatjana Pekmezovic, Vladimir Kostic, Jelena Drulovic
BACKGROUND: Gait pattern is frequently impaired in multiple sclerosis (MS), however gait characteristics in patients with different MS phenotypes have not been fully elucidated. METHODS: We analyzed spatio-temporal gait pattern characteristics in patients with relapsing-remitting (RR, n=52) and primary-progressive (PP, n=18) MS in comparison with age-matched healthy controls (HC, n=40). All subjects performed a standardized simple walking task, a dual motor- motor task, a dual motor-mental task, and a triple combined motor-mental task at a GAITRite electronic walkway of 5...
April 2017: Multiple Sclerosis and related Disorders
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