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Motivated by recent experimental findings, we have developed a theory of the superconducting state for 2D metals without inversion symmetry modeling the geometry of a surface superconducting layer in a field-effect transistor or near the boundary doped by adsorbed ions. In such systems the twofold spin degeneracy is lifted by spin-orbit interaction, and singlet and triplet pairings are mixed in the wave function of the Cooper pairs. As a result, spin magnetic susceptibility becomes anisotropic and Knight shift retains finite and rather high value at T = 0.
Tracking multiple persons in a monocular video of a crowded scene is a challenging task. Humans can master it even if they loose track of a person locally by re-identifying the same person based on their appearance. Care must be taken across long distances, as similar-looking persons need not be identical. In this work, we propose a novel graph-based formulation that links and clusters person hypotheses over time by solving an instance of a minimum cost lifted multicut problem. Our model generalizes previous works by introducing a mechanism for adding long-range attractive connections between nodes in the graph without modifying the original set of feasible solutions. This allows us to reward tracks that assign detections of similar appearance to the same person in a way that does not introduce implausible solutions. To effectively match hypotheses over longer temporal gaps we develop new deep architectures for re-identification of people. They combine holistic representations extracted with deep networks and body pose layout obtained with a state-of-the-art pose estimation model. We demonstrate the effectiveness of our formulation by reporting a new state-of-the-art for the MOT16 benchmark. The code and pre-trained models are publicly available.
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The weight of a box can be seen by observing another person lifting and carrying it. Evidence is provided in two experiments, the first of which employed videotaped events with the actor and box visible only as 21 bright patches. Observers judged the weight of the box rather linearly with an average slope of .87 and with a pooled standard deviation of 3.8 kg. The second experiment compared visual and haptic perception of box weight in similar events under conditions of live action. Average slopes of 1.00 in the visual mode and 1.20 in the haptic mode were obtained with standard deviations of 3.1 kg and 2.0 kg, respectively. It is concluded that the weight of the box, as a dynamic variable of the event, is well specified in the kinematic pattern and hence in the optic array. Furthermore, the visual system is efficient in picking up such information.
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Abstract Lifted Kramers spin degeneracy (LKSD) has been among the central topics of condensed-matter physics since the dawn of the band theory of solids 1,2 . It underpins established practical applications as well as current frontier research, ranging from magnetic-memory technology 3–7 to topological quantum matter 8–14 . Traditionally, LKSD has been considered to originate from two possible internal symmetry-breaking mechanisms. The first refers to time-reversal symmetry breaking by magnetization of ferromagnets and tends to be strong because of the non-relativistic exchange origin 15 . The second applies to crystals with broken inversion symmetry and tends to be comparatively weaker, as it originates from the relativistic spin–orbit coupling (SOC) 16–19 . A recent theory work based on spin-symmetry classification has identified an unconventional magnetic phase, dubbed altermagnetic 20,21 , that allows for LKSD without net magnetization and inversion-symmetry breaking. Here we provide the confirmation using photoemission spectroscopy and ab initio calculations. We identify two distinct unconventional mechanisms of LKSD generated by the altermagnetic phase of centrosymmetric MnTe with vanishing net magnetization 20–23 . Our observation of the altermagnetic LKSD can have broad consequences in magnetism. It motivates exploration and exploitation of the unconventional nature of this magnetic phase in an extended family of materials, ranging from insulators and semiconductors to metals and superconductors 20,21 , that have been either identified recently or perceived for many decades as conventional antiferromagnets 21,24,25 .
Idempotents can be lifted modulo a one-sided ideal <italic>L</italic> of a ring <italic>R</italic> if, given <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="x element-of upper R"> <mml:semantics> <mml:mrow> <mml:mi>x</mml:mi> <mml:mo> ∈ </mml:mo> <mml:mi>R</mml:mi> </mml:mrow> <mml:annotation encoding="application/x-tex">x \in R</mml:annotation> </mml:semantics> </mml:math> </inline-formula> with <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="x minus x squared element-of upper L"> <mml:semantics> <mml:mrow> <mml:mi>x</mml:mi> <mml:mo> − </mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>x</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> <mml:mo> ∈ </mml:mo> <mml:mi>L</mml:mi> </mml:mrow> <mml:annotation encoding="application/x-tex">x - {x^2} \in L</mml:annotation> </mml:semantics> </mml:math> </inline-formula> , there exists an idempotent <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="e element-of upper R"> <mml:semantics> <mml:mrow> <mml:mi>e</mml:mi> <mml:mo> ∈ </mml:mo> <mml:mi>R</mml:mi> </mml:mrow> <mml:annotation encoding="application/x-tex">e \in R</mml:annotation> </mml:semantics> </mml:math> </inline-formula> such that <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="e minus x element-of upper L"> <mml:semantics> <mml:mrow> <mml:mi>e</mml:mi> <mml:mo> − </mml:mo> <mml:mi>x</mml:mi> <mml:mo> ∈ </mml:mo> <mml:mi>L</mml:mi> </mml:mrow> <mml:annotation encoding="application/x-tex">e - x \in L</mml:annotation> </mml:semantics> </mml:math> </inline-formula> . Rings in which idempotents can be lifted modulo every left (equivalently right) ideal are studied and are shown to coincide with the exchange rings of Warfield. Some results of Warfield are deduced and it is shown that a projective module <italic>P</italic> has the finite exchange property if and only if, whenever <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper P equals upper N plus upper M"> <mml:semantics> <mml:mrow> <mml:mi>P</mml:mi> <mml:mo>=</mml:mo> <mml:mi>N</mml:mi> <mml:mo>+</mml:mo> <mml:mi>M</mml:mi> </mml:mrow> <mml:annotation encoding="application/x-tex">P = N + M</mml:annotation> </mml:semantics> </mml:math> </inline-formula> where <italic>N</italic> and <italic>M</italic> are submodules, there is a decomposition <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper P equals upper A circled-plus upper B"> <mml:semantics> <mml:mrow> <mml:mi>P</mml:mi> <mml:mo>=</mml:mo> <mml:mi>A</mml:mi> <mml:mo> ⊕ </mml:mo> <mml:mi>B</mml:mi> </mml:mrow> <mml:annotation encoding="application/x-tex">P = A \oplus B</mml:annotation> </mml:semantics> </mml:math> </inline-formula> with <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper A subset-of-or-equal-to upper N"> <mml:semantics> <mml:mrow> <mml:mi>A</mml:mi> <mml:mo> ⊆ </mml:mo> <mml:mi>N</mml:mi> </mml:mrow> <mml:annotation encoding="application/x-tex">A \subseteq N</mml:annotation> </mml:semantics> </mml:math> </inline-formula> and <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper B subset-of-or-equal-to upper M"> <mml:semantics> <mml:mrow> <mml:mi>B</mml:mi> <mml:mo> ⊆ </mml:mo> <mml:mi>M</mml:mi> </mml:mrow> <mml:annotation encoding="application/x-tex">B \subseteq M</mml:annotation> </mml:semantics> </mml:math> </inline-formula> .
It is shown that a sphere moving through a very viscous liquid with velocity V relative to a uniform simple shear, the translation velocity being parallel to the streamlines and measured relative to the streamline through the centre, experiences a lift force 81·2μ Va 2 k ½ / v ½ + smaller terms perpendicular to the flow direction, which acts to deflect the particle towards the streamlines moving in the direction opposite to V . Here, a denotes the radius of the sphere, κ the magnitude of the velocity gradient, and μ and v the viscosity and kinematic viscosity, respectively. The relevance of the result to the observations by Segrée & Silberberg (1962) of small spheres in Poiseuille flow is discussed briefly. Comments are also made about the problem of a sphere in a parabolic velocity profile and the functional dependence of the lift upon the parameters is obtained.
STUDY DESIGN: A 3-year prospective cohort study among workers of 34 companies in the Netherlands. OBJECTIVES: To investigate the relation between flexion and rotation of the trunk and lifting at work and the occurrence of low back pain. SUMMARY OF BACKGROUND DATA: Previous studies on work-related physical risk factors for low back pain either lacked quantification of the physical load or did not take confounding by individual and psychosocial factors into account. METHODS: The study population consisted of 861 workers with no low back pain at baseline and complete data on the occurrence of low back pain during the 3-year follow-up period. Physical load at work was assessed by means of analyses of video-recordings. Information on other risk factors and the occurrence of low back pain was obtained by means of self-administered questionnaires. RESULTS: An increased risk of low back pain was observed for workers who worked with the trunk in a minimum of 60 degrees of flexion for more than 5% of the working time (RR 1.5, 95% CI 1.0-2.1), for workers who worked with the trunk in a minimum of 30 degrees of rotation for more than 10% of the working time (RR 1.3, 95% CI 0.9-1. 9), and for workers who lifted a load of at least 25 kg more than 15 times per working day (RR 1.6, 95% CI 1.1-2.3). CONCLUSIONS: Flexion and rotation of the trunk and lifting at work are moderate risk factors for low back pain, especially at greater levels of exposure.
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We present the lifting scheme, a simple construction of second generation wavelets; these are wavelets that are not necessarily translates and dilates of one fixed function. Such wavelets can be adapted to intervals, domains, surfaces, weights, and irregular samples. We show how the lifting scheme leads to a faster, in-place calculation of the wavelet transform. Several examples are included.
In 1985, the National Institute for Occupational Safety and Health (NIOSH) convened an ad hoc committee of experts who reviewed the current literature on lifting, recommend criteria for defining lifting capacity, and in 1991 developed a revised lifting equation. Subsequently, NIOSH developed the documentation for the equation and played a prominent role in recommending methods for interpreting the results of the equation. The 1991 equation reflects new findings and provides methods for evaluating asymmetrical lifting tasks, lifts of objects with less than optimal hand-container couplings, and also provides guidelines for a larger range of work durations and lifting frequencies than the 1981 equation. This paper provides the basis for selecting the three criteria (biomechanical, physiological, and psychophysical) that were used to define the 1991 equation, and describes the derivation of the individual components (Putz-Anderson and Waters 1991). The paper also describes the lifting index (LI), an index of relative physical stress, that can be used to identify hazardous lifting tasks. Although the 1991 equation has not been fully validated, the recommended weight limits derived from the revised equation are consistent with or lower than those generally reported in the literature. NIOSH believes that the revised 1991 lifting equation is more likely than the 1981 equation to protect most workers.
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Maximal weight-lifting performance, isometric strength, isokinetic torque, whole muscle and individual fiber cross-sectional areas, and muscle evoked contractile properties were assessed in 14 elderly males before and after 12 wk of weight-lifting training. Dynamic elbow flexion training of one arm resulted in a significant 48% mean increase in the maximal load that could be lifted once (1 RM) and a smaller improvement in isokinetic torque (8.8%) but no change in isometric strength. In the contralateral control arm, 1 RM and isokinetic torque increased by 12.7 and 6.5%, respectively, but isometric strength did not change. The interpolated twitch technique confirmed complete motor unit activation during a maximal isometric contraction of the elbow flexors before and after the training. Bilateral leg press training effected mean increases of 17 and 23% in isokinetic torque and dynamic lifting capacity, respectively. The mean maximal cross-sectional area of the elbow flexors (biceps brachii and brachialis) increased by 17.4% in the trained arm but did not change the control arm. The increase in the mean area of type II fibers in the biceps brachii muscle in the trained arm (30.2%) was greater than the corresponding change in the control arm (10.7%, P less than 0.05). The most significant change in the evoked contractile properties of the trained elbow flexors was the increase in twitch half-relaxation time. It is concluded that older individuals retain the potential for significant increases in strength performance and upper limb muscle hypertrophy in response to overload training.
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ABSTRACT On the assumption that steady-state aerodynamics applies, simple analytical expressions are derived for the average lift coefficient, Reynolds number, the aerodynamic power, the moment of inertia of the wing mass and the dynamic efficiency in animals which perform normal hovering with horizontally beating wings. The majority of hovering animals, including large lamellicom beetles and sphin-gid moths, depend mainly on normal aerofoil action. However, in some groups with wing loading less than 10 N m−2 (1 kgf m−2), non-steady aerodynamics must play a major role, namely in very small insects at low Reynolds number, in true hover-flies (Syrphinae), in large dragonflies (Odonata) and in many butterflies (Lepidoptera Rhopalocera). The specific aerodynamic power ranges between 1·3 and 4·7 WN−1 (11–40 cal h−1 gf−1) but power output does not vary systematically with size, inter alia because the lift/drag ratio deteriorates at low Reynolds number. Comparisons between metabolic rate, aerodynamic power and dynamic efficiency show that the majority of insects require and depend upon an effective elastic system in the thorax which counteracts the bending moments caused by wing inertia. The free flight of a very small chalcid wasp Encarsia formosa has been analysed by means of slow-motion films. At this low Reynolds number (10–20), the high lift coefficient of 2 or 3 is not possible with steady-state aerodynamics and the wasp must depend almost entirely on non-steady flow patterns. The wings of Encarsia are moved almost horizontally during hovering, the body being vertical, and there are three unusual phases in the wing stroke: the clap, the fling and the flip. In the clap the wings are brought together at the top of the morphological upstroke. In the fling, which is a pronation at the beginning of the morphological downstroke, the opposed wings are flung open like a book, hinging about their posterior margins. In the flip, which is a supination at the beginning of the morphological upstroke, the wings are rapidly twisted through about 180°. The fling is a hitherto undescribed mechanism for creating lift and for setting up the appropriate circulation over the wing in anticipation of the downstroke. In the case of Encarsia the calculated and observed wing velocities at which lift equals body weight are in agreement, and lift is produced almost instantaneously from the beginning of the downstroke and without any Wagner effect. The fling mechanism seems to be involved in the normal flight of butterflies and possibly of Drosophila and other small insects. Dimensional and other considerations show that it could be a useful mechanism in birds and bats during take-off and in emergencies. The flip is also believed to be a means of setting up an appropriate circulation around the wing, which has hitherto escaped attention; but its operation is less well understood. It is not confined to Encarsia but operates in other insects, not only at the beginning of the upstroke (supination) but also at the beginning of the downstroke where a flip (pronation) replaces the clap and fling of Encarsia. A study of freely flying hover-flies strongly indicates that the Syrphinae (and Odonata) depend almost entirely upon the flip mechanism when hovering. In the case of these insects a transient circulation is presumed to be set up before the translation of the wing through the air, by the rapid pronation (or supination) which affects the stiff anterior margin before the soft posterior portions of the wing. In the flip mechanism vortices of opposite sense must be shed, and a Wagner effect must be present. In some hovering insects the wing twistings occur so rapidly that the speed of propagation of the elastic torsional wave from base to tip plays a significant role and appears to introduce beneficial effects. Non-steady periods, particularly flip effects, are present in all flapping animals and they will modify and become superimposed upon the steady-state pattern as described by the mathematical model presented here. However, the accumulated evidence indicates that the majority of hovering animals conform reasonably well with that model. Many new types of analysis are indicated in the text and are now open for future theoretical and experimental research.
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