pinecone/core-2020-05-10-deduplication huggingface dataset:
Nonabelian bosonization as a nonholonomic transformations from flat to curved field space

There exists a simple rule by which path integrals for the motion of a point particle in a flat space can be transformed correctly into those in curved space. This rule arose from well-established methods in the theory of plastic deformations, where crystals with defects are described mathematically by applying nonholonomic coordinate transformations to ideal crystals. In the context of time-sliced path integrals, this has given rise to a {\em quantum equivalence principle\/} which determines the measure of fluctating orbits in spaces with curvature and torsion. The nonholonomic transformations are accompanied by a nontrivial Jacobian which in curved spaces produces an additional energy proportional to the curvature scalar, thereby canceling an equal term found earlier by DeWitt from a naive formulation of Feynman's time-sliced path integral in curved space. The importance of this cancelation has been documented in various systems (H-atom, particle on the surface of a sphere, spinning top). Here we point out its relevance in the process of bosonizing a nonabelian one-dimensional quantum field theory, whose fields live in a flat field space. Its bosonized version is a quantum-mechanical path integral of a point particle moving in a space with constant curvature. The additional term introduced by the Jacobian is crucial for the identity between original and bosonized theory. A useful bozonization tool is the so-called Hubbard-Stratonovich formula for which we find a nonabelian version
On a class of invariant coframe operators with application to gravity

Let a differential 4D-manifold with a smooth coframe field be given. Consider the operators on it that are linear in the second order derivatives or quadratic in the first order derivatives of the coframe, both with coefficients that depend on the coframe variables. The paper exhibits the class of operators that are invariant under a general change of coordinates, and, also, invariant under the global SO(1,3)-transformation of the coframe. A general class of field equations is constructed. We display two subclasses in it. The subclass of field equations that are derivable from action principles by free variations and the subclass of field equations for which spherical-symmetric solutions, Minkowskian at infinity exist. Then, for the spherical-symmetric solutions, the resulting metric is computed. Invoking the Geodesic Postulate, we find all the equations that are experimentally (by the 3 classical tests) indistinguishable from Einstein field equations. This family includes, of course, also Einstein equations. Moreover, it is shown, explicitly, how to exhibit it. The basic tool employed in the paper is an invariant formulation reminiscent of Cartan's structural equations. The article sheds light on the possibilities and limitations of the coframe gravity. It may also serve as a general procedure to derive covariant field equations
A Note on the Regularity of Inviscid Shell Model of Turbulence

In this paper we continue the analytical study of the sabra shell model of
energy turbulent cascade initiated in \cite{CLT05}. We prove the global
existence of weak solutions of the inviscid sabra shell model, and show that
these solutions are unique for some short interval of time. In addition, we
prove that the solutions conserve the energy, provided that the components of
the solution satisfy $|{u_n}| \le C k_n^{-1/3} (\sqrt{n} \log(n+1))^{-1}$, for
some positive absolute constant $C$, which is the analogue of the Onsager's
conjecture for the Euler's equations. Moreover, we give a Beal-Kato-Majda type
criterion for the blow-up of solutions of the inviscid sabra shell model and
show the global regularity of the solutions in the ``two-dimensional''
parameters regime
On massless electron limit for a multispecies kinetic system with
  external magnetic field

We consider a three-dimensional kinetic model for a two species plasma
consisting of electrons and ions confined by an external nonconstant magnetic
field. Then we derive a kinetic-fluid model when the mass ratio $m_e/m_i$ tends
to zero. Each species initially obeys a Vlasov-type equation and the
electrostatic coupling follows from a Poisson equation. In our modeling, ions
are assumed non-collisional while a Fokker-Planck collision operator is taken
into account in the electron equation. As the mass ratio tends to zero we show
convergence to a new system where the macroscopic electron density satisfies an
anisotropic drift-diffusion equation. To achieve this task, we overcome some
specific technical issues of our model such as the strong effect of the
magnetic field on electrons and the lack of regularity at the limit. With
methods usually adapted to diffusion limit of collisional kinetic equations and
including renormalized solutions, relative entropy dissipation and velocity
averages, we establish the rigorous derivation of the limit model
Learning teaching strategies in an adaptive and intelligent educational system through reinforcement learning

One of the most important issues in Adaptive and Intelligent Educational Systems (AIES) is to define effective pedagogical policies for tutoring students according to their needs. This paper proposes to use Reinforcement Learning (RL) in the pedagogical module of an educational system so that the system learns automatically which is the best pedagogical policy for teaching students. One of the main characteristics of this approach is its ability to improve the pedagogical policy based only on acquired experience with other students with similar learning characteristics. In this paper we study the learning performance of the educational system through three important issues. Firstly, the learning convergence towards accurate pedagogical policies. Secondly, the role of exploration/exploitation strategies in the application of RL to AIES. Finally, a method for reducing the training phase of the AIES.Publicad
Time Series Classification by Class-Specific Mahalanobis Distance Measures

To classify time series by nearest neighbors, we need to specify or learn one or several distance measures. We consider variations of the Mahalanobis distance measures which rely on the inverse covariance matrix of the data. Unfortunately --- for time series data --- the covariance matrix has often low rank. To alleviate this problem we can either use a pseudoinverse, covariance shrinking or limit the matrix to its diagonal. We review these alternatives and benchmark them against competitive methods such as the related Large Margin Nearest Neighbor Classification (LMNN) and the Dynamic Time Warping (DTW) distance. As we expected, we find that the DTW is superior, but the Mahalanobis distance measures are one to two orders of magnitude faster. To get best results with Mahalanobis distance measures, we recommend learning one distance measure per class using either covariance shrinking or the diagonal approach
Noise-induced transitions in rugged energy landscapes

We consider the problem of an overdamped Brownian particle moving in
multiscale potential with N + 1 characteristic length scales: the macroscale
and N separated microscales. We show that the coarse-grained dynamics is given
by an overdamped Langevin equation with respect to the free energy and with a
space dependent diffusion tensor, the calculation of which requires the
solution of N fully coupled Poisson equations. We study in detail the structure
of the bifurcation diagram for one-dimensional problems and we show that the
multiscale structure in the potential leads to hysteresis effects and to
noise-induced transitions. Furthermore, we obtain an explicit formula for the
effective diffusion coefficient for a self-similar separable potential and we
investigate the limit of infinitely many small scales.Comment: 26 page
Diffusing Best Practices: A Design Science Study Using the Theory of Planned Behavior

Part 1: Creating ValueInternational audienceBoth the practice and the research literature on information systems attach great value to the identification and dissemination of information on “best practices”. In the philosophy of science, this type of knowledge is regarded as technological knowledge because it becomes manifest in the successful techniques in one context. While the value for other contexts is unproven, knowledge of best practices circulates under an assumption that the practices will usefully self-diffuse through innovation and adoption in other contexts. We study diffusion of best practices using a design science approach. The study context is a design case in which an organization desires to diffuse its best practices across different groups. The design goal is embodied in organizational mechanisms to achieve this diffusion. The study used Theory of Planned Behavior (TPB) as a kernel theory. The artifacts resulting from the design were two-day training workshops conceptually anchored to TBP. The design theory was evaluated through execution of eight diffusion workshops involving three different groups in the same company. The findings indicate that the match between the practice and the context materialized in the presence of two concordant factors. On the context side, the qualities of the selected opinion leader were necessary to provide the subjective norm described in TPB. On the best practice side, the technological qualities of the best practice itself were necessary to instill the ideal attitude (belief that the behavior will be effective). These two factors were especially critical if the source context of the best practice is qualitatively different from the target context into which the organization is seeking to diffuse the best practice
Contemporary use and practice of electroconvulsive therapy worldwide

- Published article (CC BY-NC 3.0)To explore contemporary (from 1990) utilization and practice of electroconvulsive therapy (ECT) worldwide. Systematic search (limited to studies published 1990 and after) was undertaken in the databases Medline, Embase, PsycINFO, SveMed, and EBSCO/Cinahl. Primary data-based studies/surveys with reported ECT utilization and practice in psychiatric institutions internationally, nationally, and regionally; city were included. Two reviewers independently checked study titles and abstracts according to inclusion criteria, and extracted ECT utilization and practice data from those retrieved in full text. Seventy studies were included, seven from Australia and New Zealand, three Africa, 12 North and Latin America, 33 Europe, and 15 Asia. Worldwide ECT differences and trends were evident, average number ECTs administered per patient were eight; unmodified (without anesthesia) was used in Asia (over 90%), Africa, Latin America, Russia, Turkey, Spain. Worldwide preferred electrode placement was bilateral, except unilateral at some places (Europe and Australia/New Zealand). Although mainstream was brief-pulse wave, sine-wave devices were still used. Majority ECT treated were older women with depression in Western countries, versus younger men with schizophrenia in Asian countries. ECT under involuntary conditions (admissions), use of ambulatory-ECT, acute first line of treatment, as well as administered by other professions (geriatricians, nurses) were noted by some sites. General trends were only some institutions within the same country providing ECT, training inadequate, and guidelines not followed. Mandatory reporting and overall country ECT register data were sparse. Many patients are still treated with unmodified ECT today. Large global variation in ECT utilization, administration, and practice advocates a need for worldwide sharing of knowledge about ECT, reflection, and learning from each other's experiences
Maurocalcine and domain A of the II-III loop of the dihydropyridine receptor Cav 1.1 subunit share common binding sites on the skeletal ryanodine receptor.

International audienceMaurocalcine is a scorpion venom toxin of 33 residues that bears a striking resemblance to the domain A of the dihydropyridine voltage-dependent calcium channel type 1.1 (Cav1.1) subunit. This domain belongs to the II-III loop of Cav1.1, which is implicated in excitation-contraction coupling. Besides the structural homology, maurocalcine also modulates RyR1 channel activity in a manner akin to a synthetic peptide of domain A. Because of these similarities, we hypothesized that maurocalcine and domain A may bind onto an identical region(s) of RyR1. Using a set of RyR1 fragments, we demonstrate that peptide A and maurocalcine bind onto two discrete RyR1 regions: fragments 3 and 7 encompassing residues 1021-1631 and 3201-3661, respectively. The binding onto fragment 7 is of greater importance and was thus further investigated. We found that the amino acid region 3351-3507 of RyR1 (fragment 7.2) is sufficient for these interactions. Proof that peptide A and maurocalcine bind onto the same site is provided by competition experiments in which binding of fragment 7.2 to peptide A is inhibited by preincubation with maurocalcine. Moreover, when expressed in COS-7 cells, RyR1 carrying a deletion of fragment 7 shows a loss of interaction with both peptide A and maurocalcine. At the functional level, this deletion abolishes the maurocalcine induced stimulation of [3H]ryanodine binding onto microsomes of transfected COS-7 cells without affecting the caffeine and ATP responses
Integrated optics for astronomical interferometry - VI. Coupling the light of the VLTI in K band

Our objective is to prove that integrated optics (IO) is not only a good concept for astronomical interferometry but also a working technique with high performance. We used the commissioning data obtained with the dedicated K-band integrated optics two-telescope beam combiner which now replaces the fiber coupler MONA in the VLTI/VINCI instrument. We characterize the behaviour of this IO device and compare its properties to other single mode beam combiner like the previously used MONA fiber coupler. The IO combiner provides a high optical throughput, a contrast of 89% with a night-to-night stability of a few percent. Even if a dispersive phase is present, we show that it does not bias the measured Fourier visibility estimate. An upper limit of 0.005 for the cross-talk between linear polarization states has been measured. We take advantage of the intrinsic contrast stability to test a new astronomical prodecure for calibrating diameters of simple stars by simultaneously fitting the instrumental contrast and the apparent stellar diameters. This method reaches an accuracy with diameter errors of the order of previous ones but without the need of an already known calibrator. These results are an important step of integrated optics and paves the road to incoming imaging interferometer projects
Carbon Based Substrates for Interfacing Neurons: Comparing Pristine with Functionalized Carbon Nanotubes Effects on Cultured Neuronal Networks

Pristine (as prepared) carbon nanotube (CNT) based substrates have been widely used to grow and interface neurons in culture. Nerve cells normally differentiate on CNTs and the synaptic networks, newly formed at the interface with this material, usually show an improved robustness in signal transfer. However manipulation of pristine CNTs is often prevented by their low dispersibility and tendency to aggregate in most solvents. This issue can be at least partially solved by adding solubilizing groups to the surface of CNT, which also helps improving their biocompatibility. It becomes therefore of crucial importance to determine whether chemically manipulated CNTs may maintain their performance in improving nerve signaling. Here we study and compare the impact in vitro on neuronal signaling of two classes of chemically modified multiwalled CNTs in reference to pristine CNTs, which are known to be a substrate able to boost neuronal growth and communication. We found that the extent of functionalization and the nature of the functional groups on MWNT sidewalls affect the conductivity and the biological effects of the final derivatives. This information is important for the future design of biointegrated devices
Characterization of density fluctuations during the search for an I-mode regime on the DIII-D tokamak

The I-mode regime, routinely observed on the Alcator C-Mod tokamak, is characterized by an edge energy transport barrier without an accompanying particle barrier and with broadband instabilities, known as weakly coherent modes (WCM), believed to regulate particle transport at the edge. Recent experiments on the DIII-D tokamak exhibit I-mode characteristics in various physical quantities. These DIII-D plasmas evolve over long periods, lasting several energy confinement times, during which the edge electron temperature slowly evolves towards an H-mode-like profile, while maintaining a typical L-mode edge density profile. During these periods, referred to as I-mode phases, the radial electric field at the edge also gradually reaches values typically observed in H-mode. Density fluctuations measured with the phase contrast imaging diagnostic during I-mode phases exhibit three features typically observed in H-mode on DIII-D, although they develop progressively with time and without a sharp transition: the intensity of the fluctuations is reduced; the frequency spectrum is broadened and becomes non-monotonic; two dimensional space-time spectra appear to approach those in H-mode, showing phase velocities of density fluctuations at the edge increasing to about 10 km s−1. However, in DIII-D there is no clear evidence of the WCM. Preliminary linear gyro-kinetic simulations are performed in the pedestal region with the GS2 code and its recently upgraded model collision operator that conserves particles, energy and momentum. The increased bootstrap current and flow shear generated by the temperature pedestal are shown to decrease growth rates, thus possibly generating a feedback mechanism that progressively stabilizes fluctuations.United States. Department of Energy. Office of Fusion Energy Sciences (Award DE-FG02- 94ER54235)United States. Department of Energy. Office of Fusion Energy Sciences (Award DE-FG02-94ER54084)United States. Department of Energy. Office of Fusion Energy Sciences (Award DE-FG02-08ER54984)United States. Department of Energy. Office of Fusion Energy Sciences (Award DE-FC02-04ER54698
An emerging role of mTOR in lipid biosynthesis

Lipid biosynthesis is essential for the maintenance of cellular homeostasis. The lipids produced by cells (glycerolipids, fatty acids, phospholipids, cholesterol, and sphingolipids) are used as an energy source/reserve, as building blocks for membrane biosynthesis, as precursor molecules for the synthesis of various cellular products, and as signaling molecules. Defects in lipid synthesis or processing contribute to the development of many diseases, including obesity, insulin resistance, type 2 diabetes, non-alcoholic fatty liver disease, and cancer. Studies published over the last few years have shown that the target of rapamycin (TOR), a conserved serine/threonine kinase with an important role in regulating cell growth, controls lipid biosynthesis through various mechanisms. Here, we review these findings and briefly discuss their potential relevance for human health and disease
One-watt fiber-based power-by-light system for satellite applications

In this work, a fiber-based optical powering (or power-by-light) system capable of providing more than 1 W is developed. The prototype was used in order to power a shunt regulator for controlling the activation and deactivation of solar panels in satellites. The work involves the manufacture of a light receiver (a GaAs multiple photovoltaic converter (MPC)), a power conditioning block, and a regulator and the implementation and characterization of the whole system. The MPC, with an active area of just 3.1 mm2, was able to supply 1 W at 5 V with an efficiency of 30%. The maximum measured device efficiency was over 40% at an input power (Pin) of 0.5 W. Open circuit voltage over 7 V was measured for Pin over 0.5 W. A system optoelectronic efficiency (including the optical fiber, connectors, and MPC) of 27% was measured at an output power (Pout) of 1 W. At Pout = 0.2 W, the efficiency was as high as 36%. The power conditioning block and the regulator were successfully powered with the system. The maximum supplied power in steady state was 0.2 W, whereas in transient state, it reached 0.44 W. The paper also describes the characterization of the system within the temperature range going from -70 to +100?°C
A simple model of the commercial lobbying industry

In this paper we present a model of the behavior of commercial lobbying firms (such as the so-called K-Street lobbyists of Washington, D.C.). In contrast to classical special interest groups, commercial lobbying firms represent a variety of clients and are not directly affected by policy outcomes. They are hired by citizens, or groups of citizens, to advocate on their behalf to policymakers. In our analysis we address two basic questions; why do commercial lobbying firms exist, and what are the implications of their existence for social welfare? We answer the first part of this question by proposing that commercial lobbying firms possess a verification technology that allows them to improve the quality of information concerning the social desirability of policy proposals. This gives policymakers the incentive to allocate their scarce time to lobbying firms. Essentially it is this access to policymakers that lobbying firms sell to their clients. To address the question of social welfare we construct a simple general equilibrium model that includes commercial lobbying firms, and compare the equilibrium obtained under market provision of lobbying services to the first best optimum. We find that the market level of lobbying services can be socially either too large or too small, and characterize when each will be the case.
Spatial sensory organization and body representation in pain perception

Pain is a subjective experience that protects the body. This function implies a special relation between the brain mechanisms underlying pain perception and representation of the body. All sensory systems involve the body for the trivial reason that sensory receptors are located in the body. The nociceptive system of detecting noxious stimuli comprises two classes of peripheral afferents, Aδ and C nociceptors, that cover almost the entire body surface. We review evidence from experimental studies of pain in humans and other animals suggesting that Aδ skin nociceptors project to a spatially-organised, somatotopic map in the primary somatosensory cortex. While the relation between pain perception and homeostatic regulation of bodily systems is widely acknowledged, the organization of nociceptive information into spatial maps of the body has received little attention. Importantly, the somatotopic neural organization of pain systems can shed light on pain-related plasticity and pain modulation. Finally, we show that the neural coding of noxious stimuli, and consequent experience of pain, are both strongly influenced when cognitive representations of the body are activated by viewing the body, as opposed to viewing another object — an effect we term ‘visual analgesia’. We argue that pain perception involves some of the representational properties of exteroceptive senses, such as vision and touch. Pain, however, has the unique feature that the content of representation is the body itself, rather than any external object of perception. We end with some suggestions regarding how linking pain to body representation could shed light on clinical conditions, notably chronic pain