2,889 research outputs found

    Orbital order in bilayer graphene at filling factor ν=1\nu =-1

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    In a graphene bilayer with Bernal stacking both n=0n=0 and n=1n=1 orbital Landau levels have zero kinetic energy. An electronic state in the N=0 Landau level consequently has three quantum numbers in addition to its guiding center label: its spin, its valley index KK or KK^{\prime}, and an orbital quantum number n=0,1.n=0,1. The two-dimensional electron gas (2DEG) in the bilayer supports a wide variety of broken-symmetry states in which the pseudospins associated these three quantum numbers order in a manner that is dependent on both filling factor ν\nu and the electric potential difference between the layers. In this paper, we study the case of ν=1\nu =-1 in an external field strong enough to freeze electronic spins. We show that an electric potential difference between layers drives a series of transitions, starting from interlayer-coherent states (ICS) at small potentials and leading to orbitally coherent states (OCS) that are polarized in a single layer. Orbital pseudospins carry electric dipoles with orientations that are ordered in the OCS and have Dzyaloshinskii-Moriya interactions that can lead to spiral instabilities. We show that the microwave absorption spectra of ICSs, OCSs, and the mixed states that occur at intermediate potentials are sharply distinct.Comment: 21 pages, 14 figure

    Finite-size scaling at infinite-order phase transitions

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    For systems with infinite-order phase transitions, in which an order parameter smoothly becomes nonzero, a new observable for finite-size scaling analysis is suggested. By construction this new observable has the favourable property of diverging at the critical point. Focussing on the example of the F-model we compare the analysis of this observable with that of another observable, which is also derived from the order parameter but does not diverge, as well as that of the associated susceptibility. We discuss the difficulties that arise in the finite-size scaling analysis of such systems. In particular we show that one may reach incorrect conclusions from large-system size extrapolations of observables that are not known to diverge at the critical point. Our work suggests that one should base finite-size scaling analyses for infinite-order phase transitions only on observables that are guaranteed to diverge.Comment: 7 pages, 5 figures, 1 table; v2: publication details adde

    Keck Measurement of the XTE J2123-058 Radial Velocity Curve

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    We measured the radial velocity curve of the companion of the neutron star X-ray transient XTE J2123-058. Its semi-amplitude (K_2) of 298.5 +/- 6.9 km/s is the highest value that has been measured for any neutron star LMXB. The high value for K_2 is, in part, due to the high binary inclination of the system but may also indicate a high neutron star mass. The mass function (f_2) of 0.684 +/- 0.047 solar masses, along with our constraints on the companion's spectral type (K5V-K9V) and previous constraints on the inclination, gives a likely range of neutron star masses from 1.2 to 1.8 solar masses. We also derive a source distance of 8.5 +/- 2.5 kpc, indicating that XTE J2123-058 is unusually far, 5.0 +/- 1.5 kpc, from the Galactic plane. Our measurement of the systemic radial velocity is -94.5 +/- 5.5 km/s, which is significantly different from what would be observed if this object corotates with the disk of the Galaxy.Comment: 4 pages, accepted by ApJ Letters after minor revision

    Alien Registration- Dube, Jules A. (Brunswick, Cumberland County)

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    https://digitalmaine.com/alien_docs/31454/thumbnail.jp

    A Comparison of the Application to Architecture of the Ecological and Gestalt Approaches to Visual Perception

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    This research is a comparison of two psychological theories of visual perception, Gestalt Theory and an Ecological Theory developed by J. J. Gibson, with two theories of architectural composition, theories developed by the Ecole des Beaux-Arts and theories of the Modern Movement in architecture. The objective of the research is to clarify the relation between the psychology of perception and building composition, and thereby to affect how architects are educated and practice.https://dc.uwm.edu/caupr_mono/1039/thumbnail.jp

    Stressors in anaesthesiology: development and validation of a new questionnaire: A cross-sectional study of Portuguese anaesthesiologists

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    BACKGROUND: Stress in anaesthesiologists is a common and multifactorial problem related to patients, colleagues and organisations. The consequences of stress include depression, work-home conflicts and burnout. Reduction in stress can be achieved by reducing the number and magnitude of stressors or by increasing resilience strategies. OBJECTIVES: We have created the self-reporting 'Stress Questionnaire in Anaesthesiologists' (SQA), to qualify the sources of stress in anaesthesiologists' professional lives, and measure the level of associated stress. Our study aimed to develop and validate the SQA using exploratory and confirmatory factor analyses. Construct validity was assessed through correlations between SQA and negative psychological outcomes as well as by comparing perception of stress among different known groups. DESIGN: A questionnaire-based cross-sectional, correlational, observational study. SETTINGS: The study was conducted between January 2014 and December 2014, throughout different anaesthesia departments in Portuguese hospitals. Data collection was from a representative subset at one specific time point. PARTICIPANTS: A sample of 710 anaesthesia specialists and residents from Portugal. MAIN OUTCOME MEASURES: The primary outcome measure was to identify specific stressors in anaesthesiologists. Secondary outcome was the association between stressors and burnout, depression symptoms, anxiety, stress, rumination, satisfaction with life and functional impairment. RESULTS: The exploratory analysis showed the SQA is a tri-dimensional instrument and confirmatory analysis showed the tri-dimensional structure presented good model fit. The three dimensions of SQA correlated positively with other stress measures and burnout, but negatively with satisfaction with life. CONCLUSION: SQA is a well adjusted measure for assessing stressors in anaesthesia physicians and includes clinical, organisational and team stress factors. Results showed that the SQA is a robust and reliable instrument.info:eu-repo/semantics/publishedVersio

    Rotation of an immersed cylinder sliding near a thin elastic coating

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    It is known that an object translating parallel to a soft wall in a viscous fluid produces hydro- dynamic stresses that deform the wall, which, in turn, results in a lift force on the object. Recent experiments with cylinders sliding under gravity near a soft incline, which confirmed theoretical arguments for the lift force, also reported an unexplained steady-state rotation of the cylinders [Saintyves et al. PNAS 113(21), 2016]. Motivated by these observations, we show, in the lubrication limit, that an infinite cylinder that translates in a viscous fluid parallel to a soft wall at constant speed and separation distance must also rotate in order to remain free of torque. Using the Lorentz reciprocal theorem, we show analytically that for small deformations of the elastic layer, the angular velocity of the cylinder scales with the cube of the sliding speed. These predictions are confirmed numerically. We then apply the theory to the gravity-driven motion of a cylinder near a soft incline and find qualitative agreement with the experimental observations, namely that a softer elastic layer results in a greater angular speed of the cylinder.Comment: 16 pages, 4 figure
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