pinecone/core-2020-05-10-deduplication huggingface dataset:
Direct Vlasov simulations of electron-attracting cylindrical Langmuir probes in flowing plasmas

Current collection by positively polarized cylindrical Langmuir probes immersed in flowing plasmas is analyzed using a non-stationary direct Vlasov-Poisson code. A detailed description of plasma density spatial structure as a function of the probe-to-plasma relative velocity U is presented. Within the considered parametric domain, the well-known electron density maximum close to the probe is weakly affected by U. However, in the probe wake side, the electron density minimum becomes deeper as U increases and a rarified plasma region appears. Sheath radius is larger at the wake than at the front side. Electron and ion distribution functions show specific features that are the signature of probe motion. In particular, the ion distribution function at the probe front side exhibits a filament with positive radial velocity. It corresponds to a population of rammed ions that were reflected by the electric field close to the positively biased probe. Numerical simulations reveal that two populations of trapped electrons exist: one orbiting around the probe and the other with trajectories confined at the probe front side. The latter helps to neutralize the reflected ions, thus explaining a paradox in past probe theory
Non-abelian dark matter solutions for Galactic gamma-ray excess and Perseus 3.5 keV X-ray line

We attempt to explain simultaneously the Galactic center   gamma-ray excess and the 3.5 keV X-ray line from the Perseus cluster   based on a class of non-abelian SU(2) DM models, in which the dark   matter and an excited state comprise a ``dark'' SU(2) doublet.   The non-abelian group kinetically mixes with the standard model   gauge group via dimensions-5 operators.  The dark matter particles   annihilate into standard model fermions, followed by fragmentation   and bremsstrahlung, and thus producing a continuous spectrum of   gamma-rays.  On the other hand, the dark matter particles can   annihilate into a pair of excited states, each of which decays back   into the dark matter particle and an X-ray photon, which has an   energy equal to the mass difference between the dark matter and the   excited state, which is set to be 3.5 keV.  The large hierarchy   between the required X-ray and γ-ray annihilation cross-sections   can be achieved by a very small kinetic mixing between the SM and   dark sector, which effectively suppresses the annihilation into the   standard model fermions but not into the excited state
Entanglement thermodynamics for an excited state of Lifshitz system

A class of (2+1)-dimensional quantum many body system characterized by an anisotropic scaling symmetry (Lifshitz symmetry) near their quantum critical point can be described by a (3+1)-dimensional dual gravity theory with negative cosmological constant along with a massive vector field, where the scaling symmetry is realized by the metric as an isometry. We calculate the entanglement entropy of an excited state of such a system holographically, i.e., from the asymptotic perturbation of the gravity dual using the prescription of Ryu and Takayanagi, when the subsystem is sufficiently small. With suitable identifications, we show that this entanglement entropy satisfies an energy conservation relation analogous to the first law of thermodynamics. The non-trivial massive vector field here plays a crucial role and contributes to an additional term in the energy relation
Structure of Lefschetz thimbles in simple fermionic systems

The Picard-Lefschetz theory offers a promising tool to solve the sign problem in QCD and other field theories with complex path-integral weight. In this paper the Lefschetz-thimble approach is examined in simple fermionic models which share some features with QCD. In zero-dimensional versions of the Gross-Neveu model and the Nambu-Jona-Lasinio model, we study the structure of Lefschetz thimbles and its variation across the chiral phase transition. We map out a phase diagram in the complex four-fermion coupling plane using a thimble decomposition of the path integral, and demonstrate an interesting link between anti-Stokes lines and Lee-Yang zeros. In the case of nonzero mass, it is shown that the approach to the chiral limit is singular because of intricate cancellation between competing thimbles, which implies the necessity to sum up multiple thimbles related by symmetry. We also consider a Chern-Simons theory with fermions in 0 + 1-dimension and show how Lefschetz thimbles solve the complex phase problem caused by a topological term. These prototypical examples would aid future application of this framework to bona fide QCD
Generalized gravitational entropy without replica symmetry

We explore several extensions of the generalized entropy construction of Lewkowycz and Maldacena, including a formulation that does not rely on preserving replica symmetry in the bulk. We show that an appropriately general ansatz for the analytically continued replica metric gives us the flexibility needed to solve the gravitational field equations beyond general relativity. As an application of this observation we study EinsteinGauss-Bonnet gravity with a small Gauss-Bonnet coupling and derive the condition that the holographic entanglement entropy must be evaluated on a surface which extremizes the Jacobson-Myers entropy. We find that in both general relativity and Einstein-Gauss-Bonnet gravity replica symmetry breaking terms are permitted by the field equations, suggesting that they do not generically vanish
Towards a holographic Bose-Hubbard model

We present a holographic construction of the large-N Bose-Hubbard model. The model is based on Maxwell fields coupled to charged scalar fields on the AdS<inf>2</inf> hard wall. We realize the lobe-shaped phase structure of the Bose-Hubbard model and find that the model admits Mott insulator ground states in the limit of large Coulomb repulsion. In the Mott insulator phases, the bosons are localized on each site. At zero hopping we find that the transitions between Mott insulating phases with different fillings correspond to first order level-crossing phase transitions. At finite hopping we find a holographic phase transition between the Mott phase and a non-homogeneous phase. We then analyze the perturbations of fields around both the Mott insulator phase and inhomogeneous phase. We find almost zero modes in the non-homogeneous phase
New developments in cerebral blood flow autoregulation analysis in preterm infants: a mechanistic approach

Background:\ud
Impaired autoregulation capacity implies that changes in cerebral perfusion follow changes in blood pressure; however, no analytical method has explored such a signal causality relationship in infants. We sought to develop a method to assess cerebral autoregulation from a mechanistic point of view and explored the predictive capacity of the method to classify infants at risk for adverse outcomes.\ud
\ud
Methods:\ud
The partial directed coherence (PDC) method, which considers synchronicity and directionality of signal dependence across frequencies, was used to analyze the relationship between spontaneous changes in mean arterial pressure (MAP) and the cerebral tissue oxygenation index (TOI). PDCMAP>>TOI indicated that changes in TOI were induced by MAP changes, and PDCTOI>>MAP indicated the opposite.\ud
\ud
Results:\ud
The PDCMAP>>TOI and PDCTOI>>MAP values differed. PDCMAP>>TOI adjusted by gestational age predicted low superior vena cava flow (≤41 ml/kg per min), with an area under the receiver operating characteristic curve of 0.72 (95% CI: 0.63–0.81; P < 0.001), whereas PDCTOI>>MAP did not. The adjusted pPDCMAP>>TOI (the average value per patient) predicted severe intracranial hemorrhage and mortality.\ud
\ud
Conclusion:\ud
PDCMAP>>TOI allows for a noninvasive physiological interpretation of the pressure autoregulation process in neonates. PDCMAP>>TOI is a good classifier for infants at risk of brain hypoperfusion and adverse outcomes
Competition and Complementarity in Diffusion: The Case of Octane

The standard ontogenic (life-cycle) model of technological evolution can be characterized briefly as follows (Ayres, 1987): (1) a radical invention (birth) creates a new technology; (2) it is commercialized on the basis of performance and rapidly developed by a series of improvements and modifications (infancy); (3) it is successful enough in the marketplace to attract many variants and imitators who hope to exploit a growing market (adolescence); (4) the pace of technological change finally slows down enough to permit standardization and exploitation of economies of scale, and competition on the basis of price rather than performance (maturity); and finally a new and better technology supplants it (senescence)
Cluster formation in compact stars: relativistic versus Skyrme models

We present various properties of nuclear and compact-star matter, comparing the predictions from two kinds of phenomenological approaches: relativistic models (both with constant and density-dependent couplings) and non-relativistic Skyrme-type interactions. We mainly focus on the liquid-gas instabilities that occur at sub-saturation densities, leading to the decomposition of the homogeneous matter into a clusterized phase. Such study is related to the description of neutron-star crust (at zero temperature) and of supernova dynamics (at finite temperature)
Probing the nuclear matter isospin asymmetry by nucleon-induced reactions at Fermi energies

Despite the fact that valuable experimental measures are still lacking, available nuclear data on nucleon-induced reactions open new opportunities to address either reaction mechanisms or nuclear interaction characteristics. In this work single and double differential cross sections of emitted particles are analyzed and compared with the experiment. It will be evidenced that these cross sections follow a precise hierarchy. The preequilibrium components of the spectra are built up by the dynamics of the reaction as well as by the properties of the nuclear interaction
Micro-PIXE characterization of interactions between a sol-gel derived bioactive glass and biological fluids

Bioactive glasses possess the ability to bond to living tissues through the formation of a calcium phosphate-rich layer at their interface with living tissues. This paper reports the different steps of this bioactivity process via a complete micro-PIXE characterization of a sol-gel derived SiO2-CaO bioactive glass in contact with biological fluids for different delays. Multi-elemental cartography at the glass/biological fluids interface together with major and trace elements quantification permit a better understanding of the five reaction stages involved in the bioactivity mechanisms. The presence of phosphorus was detected at the periphery of the material within 6 h of interaction with biological fluids. A calcium phosphate-rich layer containing magnesium is formed after a few days of interaction and presence of bone-like apatite is deduced from the calculation of the Ca/P ratio at the material interface. That is of deep interest for clinical applications, because this biologically active behavior results in the formation of a strong interfacial bond between the glass and host tissues, and will stimulate bone-cell proliferation
Charged pion production in fixed target Pb + Pb collisions at 158 GeV per nucleon

Changes in pion production as a function of the impact parameter of the collision or the incident energy, may reveal characteristics of a possible first-order phase transition from nuclear to quark matter, as predicted by lattice quantum chromodynamics. In this paper we investigate charged pion production in Pb+Pb collisions at 158 GeV/nucleon near 0° production angle and at forward rapidity $(4.3\leq y \leq 6.3)$. The centrality dependence of pion production is shown in the impact parameter range ~ 2-12 fm at the rapidities y = 5.7 and 6.3. An enhancement in the pi-/pi+ ratio has been measured near beam rapidity, indicating Coulomb interaction of charged pions with the spectator protons. The charged pion yield per nucleon participating in the collision (N_p) at y = 5.7 increases faster than linearly with N_p, up to N_p~100 and then it saturates, while at y = 6.3 it does not exhibit any sudden change as a function of N_p
Somatic mutations activating STAT3 in human inflammatory hepatocellular adenomas.
 : 
Activating STAT3 mutations in hepatocellular adenoma

International audienceInflammatory hepatocellular adenomas (IHCAs) are benign liver tumors. 60% of these tumors have IL-6 signal transducer (IL6ST; gp130) mutations that activate interleukin 6 (IL-6) signaling. Here, we report that 12% of IHCA subsets lacking IL6ST mutations harbor somatic signal transducer and activator of transcription 3 (STAT3) mutations (6/49). Most of these mutations are amino acid substitutions in the SH2 domain that directs STAT3 dimerization. In contrast to wild-type STAT3, IHCA STAT3 mutants constitutively activated the IL-6 signaling pathway independent of ligand in hepatocellular cells. Indeed, the IHCA STAT3 Y640 mutant homodimerized independent of IL-6 and was hypersensitive to IL-6 stimulation. This was associated with phosphorylation of tyrosine 705, a residue required for IL-6-induced STAT3 activation. Silencing or inhibiting the tyrosine kinases JAK1 or Src, which phosphorylate STAT3, impaired constitutive activity of IHCA STAT3 mutants in hepatocellular cells. Thus, we identified for the first time somatic STAT3 mutations in human tumors, revealing a new mechanism of recurrent STAT3 activation and underscoring the role of the IL-6-STAT3 pathway in benign hepatocellular tumorigenesis
Fluctuations of correlations and Green's function reconstruction: role of scattering

International audienceCorrelations of ambient seismic or acoustic vibrations are now widely used to reconstruct the impulse response between two passive receivers as if a source was placed at one of them. This provides the opportunity to do imaging without a source, or \textsl{passive imaging}. Applications include terrestrial and solar seismology, underwater acoustics, and structural health monitoring, to cite only a few. Nevertheless, for a given set of data, correlations do not only yield the Green's function between the sensors. They also contain residual fluctuations that result from an imperfect time or source averaging that might eventually blur the images. In this article, we propose a heuristic model to describe the level of fluctuations of the correlations in the case of non-stationary wavefields, and more particularly in the case of scattering media. The work includes theoretical derivations and numerical simulations. The role of multiple scattering is quantitatively evaluated. The level of fluctuations decreases when the duration and intensity of the diffuse waves increase. The role of absorption is also discussed: absorption is properly retrieved by correlation, but the level of fluctuations is greater, thus degrading the Green's function reconstruction. Discrepancies of our simple model in the case of strong multiple scattering ($k\ell^*\leq 18$) are discussed
Serum calcitriol concentrations measured with a new direct automated assay in a large population of adult healthy subjects and in various clinical situations

International audienceThe measurement of calcitriol [1,25(OH2)D], is important for the differential diagnosis of several disorders of calcium/phosphorus metabolism but is time-consuming and tricky. We measured serum calcitriol with a new automated direct assay on the Liaison XL platform in 888 healthy French Caucasian subjects aged 18–89 years, 32 patients with a surgically-proven PHPT, 32 pregnant women at the end of the first and at the end of the third trimester, and 24 Dialysis patients before and after one year of supplementation with vitamin D3 or placebo. The mean calcitriol concentration (± SD) in the healthy population was 52.9 ± 14.5 ng/L with a 95% CI interval of 29–83.6 ng/L. In PHPT patients, calcitriol concentration was 81.6 ± 29.0 ng/L, 15 of them (46.9%) having a concentration &gt; 83.6 ng/L. In pregnant women, calcitriol was 80.4 ± 26.4 ng/L at the end of the first trimester, and 113.1 ± 33.0 ng/L at the end of the third trimester, 12 (37.5%) and 26 (81.3%) of them having a calcitriol &gt; 83.6 ng/L at first and third trimester respectively. In 14 dialysis patients, calcitriol was 9.5 ± 7.7 ng/L and rose to 19.3 ng/L after one year of supplementation with 50,000 IU vitamin D3/month. In 10 other dialysis patients, calcitriol was 9.9 ± 2.9 ng/L and remained stable (12.4 ± 3.7 ng/L) after one year of placebo. In conclusion, this new automated calcitriol assay, in addition to presenting excellent analytical performances, gives the expected variations in patients compared to “normal” values obtained in an extensive reference populatio
Volume-Aware Positioning in the Context of a Marine Port Terminal

International audienceThe rapid proliferation of mobile computing devices and local wireless networks over the past few years has promoted a continuously growing interest in location-aware systems and applications. The main problem with existing positioning techniques is that they are designed to position dimensionless objects. Such an assumption may lead to practical inconsistencies, as it results in neglecting the effects of the volume of an object, its physical characteristics, and its spatial arrangement on signal propagation. In this paper, we consider the problem of positioning cargo containers in a marine port terminal, where such characteristics can be finely estimated. Based on the signal propagation map of a container yard, we propose VAPS, a volume-aware positioning system that takes advantage of the waveguide effect generated by the containers. Although VAPS is specific to the marine port scenario, its design principles can be extended and adapted to other situations. VAPS maps discrete RSSI levels into hop-counts and relies on realistic propagation models to obtain near-perfect positioning at a very low control overhead. Our extensive evaluations show how to set the parameters required in the VAPS algorithm. The results demonstrate that, in scenarios where the assumptions made by traditional approaches fail, the considerations of VAPS make the difference
Epigraphical splitting for solving constrained convex optimization problems with proximal tools

International audienceWe propose a proximal approach to deal with a class of convex variational problems involving nonlinear constraints. A large family of constraints, proven to be effective in the solution of inverse problems, can be expressed as the lower level set of a sum of convex functions evaluated over different blocks of the linearly-transformed signal. For such constraints, the associated projection operator generally does not have a simple form. We circumvent this difficulty by splitting the lower level set into as many epigraphs as functions involved in the sum. In particular, we focus on constraints involving q-norms with q ≥ 1, distance functions to a convex set, and L1,p-norms with p ∈ {2, +∞}. The proposed approach is validated in the context of image restoration by making use of constraints based on Non-Local Total Variation. Experiments show that our method leads to significant improvements in term of convergence speed over existing algorithms for solving similar constrained problems. A second application to a pulse shape design problem is provided in order to illustrate the flexibility of the proposed approach
Upper Bounding in Inner Regions for Global Optimization under Inequality Constraints

International audienceIn deterministic continuous constrained global optimization, upper bounding the objective function generally resorts to local minimization at several nodes/iterations of the branch and bound. We propose in this paper an alternative approach when the constraints are inequalities and the feasible space has a non-null volume. First, we extract an inner region , i.e., an entirely feasible convex polyhedron or box in which all points satisfy the constraints. Second, we select a point inside the extracted inner region and update the upper bound with its cost. We describe in this paper two original inner region extraction algorithms implemented in our interval B&B called IbexOpt. They apply to nonconvex constraints involving mathematical operators like +,x,power,sqrt,exp,log,sin. This upper bounding shows very good performance obtained on medium-sized systems proposed in the COCONUT suite
A testing technique for concrete under confinement at high rates of strain

International audienceA testing device is presented for the experimental study of dynamic compaction of concrete under high strain rates. The specimen is confined in a metallic ring and loaded by means of a hard-steel Hopkinson pressure bar (80 mm diameter, 6 m long) allowing for the testing of specimens large enough regarding the aggregate size. The constitutive law for the metal of the ring being known, transverse gauges glued on its lateral surface allow for the measurement of the confining pressure. The hydrostatic and deviatoric responses of the specimen can then be computed. The proposed method is validated by several numerical simulations of tests involving a set of four different concrete-like behaviours and different friction coefficients between the cell and the specimen. Finally, three tests performed with the MB50 concrete at three different strain rates are processed with the method and are compared with literature results for the same material under quasi-static loadings
Borehole seismoelectric logging using a shear-wave source: Possible application to CO2 disposal?

International audienceThe behaviour of CO2 deposition sites-and their surroundings-during and after carbon dioxide injection has  been matter of study for several years, and several geophysical prospection techniques like surface and crosshole seismics, geoelectrics, controlled source electromagnetics among others, have been applied to characterize the behaviour of the gas in the reservoirs. Until now, Seismolectromagnetic wave conversions occuring in poroelastic media via electrokinetic coupling have not been tested for this purpose. In this work, by means of numerical experiments using Pride's equations-extended to deal with partial saturations-we show that  the seismoelectric and seismomagnetic interface responses (IR) generated at boundaries of a layer containing carbon dioxide are sensitive to its CO2 content. Further, modeling shear wave sources in surface to borehole seismoelectric layouts and employing two different models for the saturation dependence of the electrokinetic coefficient, we observe that the IR are sensitive to CO2 saturations ranging between 10% and 90%, and that the CO2 saturation at which the IR maxima are reached depends on the aforementioned models. Moreover, the IR are still sensitive to different CO2 saturations for a sealed CO2 reservoir covered by a clay layer. These results, which should be complemented by the analysis of the IR absolute amplitude, could lead, once confirmed on the field, to a new monitoring tool complementing existing ones
Piecewise polynomial monotonic interpolation of 2D gridded data

International audienceA method for interpolating monotone increasing 2D scalar data with a monotone piecewise cubic C$^1$-continuous surface is presented. Monotonicity is a sufficient condition for a function to be free of critical points inside its domain. The standard axial monotonicity for tensor-product surfaces is however too restrictive. We therefore introduce a more relaxed monotonicity constraint. We derive sufficient conditions on the partial derivatives of the interpolating function to ensure its monotonicity. We then develop two algorithms to effectively construct a monotone C$^1$ surface composed of cubic triangular Bézier surfaces interpolating a monotone gridded data set. Our method enables to interpolate given topological data such as minima, maxima and saddle points at the corners of a rectangular domain without adding spurious extrema inside the function domain. Numerical examples are given to illustrate the performance of the algorithm