Trade Liberalization, Input Intermediaries and Firm Productivity: Evidence from China

We investigate theoretically and empirically the role of wholesalers in mediating the productivity effects of trade liberalization. Intermediaries provide indirect access to foreign produced inputs. The productivity effects of input tariff cuts on firms that do not directly import therefore depends on the extent that wholesalers are a feature of input supply within an industry. Using firm level data from China, we document that wholesalers play no such role for direct importers. However, other firms experience productivity gains from reducing input tariffs if trade intermediation of foreign inputs within their sector is high. They suffer efficiency losses otherwise

Neutrinos from type Ia supernovae: the deflagration-to-detonation transition scenario

It has long been recognized that the neutrinos detected from the next core-collapse supernova in the Galaxy have the potential to reveal important information about the dynamics of the explosion and the nucleosynthesis conditions as well as allowing us to probe the properties of the neutrino itself. The neutrinos emitted from thermonuclear - type Ia - supernovae also possess the same potential, although these supernovae are dimmer neutrino sources. For the first time, we calculate the time, energy, line of sight, and neutrino-flavor-dependent features of the neutrino signal expected from a three-dimensional delayed-detonation explosion simulation, where a deflagration-to-detonation transition triggers the complete disruption of a near-Chandrasekhar mass carbon-oxygen white dwarf. We also calculate the neutrino flavor evolution along eight lines of sight through the simulation as a function of time and energy using an exact three-flavor transformation code. We identify a characteristic spectral peak at $\sim 10$ MeV as a signature of electron captures on copper. This peak is a potentially distinguishing feature of explosion models since it reflects the nucleosynthesis conditions early in the explosion. We simulate the event rates in the Super-K, Hyper-K, JUNO, and DUNE neutrino detectors with the SNOwGLoBES event rate calculation software and also compute the IceCube signal. Hyper-K will be able to detect neutrinos from our model out to a distance of $\sim 10$ kpc. At 1 kpc, JUNO, Super-K, and DUNE would register a few events while IceCube and Hyper-K would register several tens of events.Comment: 44 pages, 29 figures & 2 tables. Updated to match Phys. Rev. D version, including a new event channel discussion and improved IceCube result

Holonomic constraints : an analytical result

Systems subjected to holonomic constraints follow quite complicated dynamics that could not be described easily with Hamiltonian or Lagrangian dynamics. The influence of holonomic constraints in equations of motions is taken into account by using Lagrange multipliers. Finding the value of the Lagrange multipliers allows to compute the forces induced by the constraints and therefore, to integrate the equations of motions of the system. Computing analytically the Lagrange multipliers for a constrained system may be a difficult task that is depending on the complexity of systems. For complex systems, it is most of the time impossible to achieve. In computer simulations, some algorithms using iterative procedures estimate numerically Lagrange multipliers or constraint forces by correcting the unconstrained trajectory. In this work, we provide an analytical computation of the Lagrange multipliers for a set of linear holonomic constraints with an arbitrary number of bonds of constant length. In the appendix of the paper, one would find explicit formulas for Lagrange multipliers for systems having 1, 2, 3, 4 and 5 bonds of constant length, linearly connected.Comment: 13 pages, no figures. To appear in J. Phys. A : Math. The

NMscatt: a program for calculating inelastic scattering from large biomolecular systems using classical force-field simulations

Computational tools for normal mode analysis, which are widely used in physics and materials science problems, are designed here in a single package called NMscatt (Normal Modes & scattering) that allows arbitrarily large systems to be handled. The package allows inelastic neutron and X-ray scattering observables to be calculated, allowing comparison with experimental data produced at large scale facilities. Various simplification schemes are presented for analysing displacement vectors, which are otherwise too complicated to understand in very large systems.Comment: 13 pages, 5 figures, preprint submitted to Computer Physics Communication

BBN For Pedestrians

The simplest, `standard' model of Big Bang Nucleosynthesis (SBBN) assumes three light neutrinos (N_nu = 3) and no significant electron neutrino asymmetry, leaving only one adjustable parameter: the baryon to photon ratio eta. The primordial abundance of any one nuclide can, therefore, be used to measure the baryon abundance and the value derived from the observationally inferred primordial abundance of deuterium closely matches that from current, non-BBN data, primarily from the WMAP survey. However, using this same estimate there is a tension between the SBBN-predicted 4He and 7Li abundances and their current, observationally inferred primordial abundances, suggesting that N_nu may differ from the standard model value of three and/or that there may be a non-zero neutral lepton asymmetry (or, that systematic errors in the abundance determinations have been underestimated or overlooked). The differences are not large and the allowed ranges of the BBN parameters permitted by the data are quite small. Within these ranges, the BBN-predicted abundances of D, 3He, 4He, and 7Li are very smooth, monotonic functions of eta, N_nu, and the lepton asymmetry. It is possible to describe the dependencies of these abundances (or powers of them) upon the three parameters by simple, linear fits which, over their ranges of applicability, are accurate to a few percent or better. The fits presented here have not been maximized for their accuracy but, for their simplicity. To identify the ranges of applicability and relative accuracies, they are compared to detailed BBN calculations; their utility is illustrated with several examples. Given the tension within BBN, these fits should prove useful in facilitating studies of the viability of proposals for non-standard physics and cosmology, prior to undertaking detailed BBN calculations.Comment: Submitted to a Focus Issue on Neutrino Physics in New Journal of Physics (www.njp.org

Enhancement of the superconducting transition temperature in Nb/Permalloy bilayers by controlling the domain state of the ferromagnet

In (S/F) hybrids the suppression of superconductivity by the exchange field h_ex of the ferromagnet can be partially lifted when different directions of h_ex are sampled simultaneously by the Cooper pair. In F/S/F trilayer geometries where the magnetization directions of the two F-layers can be controlled separately, this leads to the so-called spin switch. Here we show that domain walls in a single F-layer yield a similar effect. We study the transport properties of Ni_0.8Fe_0.2/Nb bilayers structured in strips of different sizes. For large samples a clear enhancement of superconductivity takes place in the resistive transition, in the very narrow field range (order of 0.5 mT) where the magnetization of the Py layer switches and many domains are present. This effect is absent in microstructured samples. Comparison of domain wall width \delta_w to the temperature dependent superconductor coherence length \xi_S(T) shows that \delta_w ~ \xi_S(T), which means that the Cooper pairs sample a large range of different magnetization directions.Comment: 4 pages, 5 figure

Diffusion and jump-length distribution in liquid and amorphous Cu33_{33}Zr67_{67}

Using molecular dynamics simulation, we calculate the distribution of atomic jum ps in Cu$_{33}$Zr$_{67}$ in the liquid and glassy states. In both states the distribution of jump lengths can be described by a temperature independent exponential of the length and an effective activation energy plus a contribution of elastic displacements at short distances. Upon cooling the contribution of shorter jumps dominates. No indication of an enhanced probability to jump over a nearest neighbor distance was found. We find a smooth transition from flow in the liquid to jumps in the g lass. The correlation factor of the diffusion constant decreases with decreasing temperature, causing a drop of diffusion below the Arrhenius value, despite an apparent Arrhenius law for the jump probability

Longitudinal flow evolution and turbulence structure of dynamically similar, sustained, saline density and turbidity currents

Experimental results are presented concerning flow evolution and turbulence structure of sustained saline and turbidity flows generated on 0°, 3°, 6°, and 9° sloping ramps that terminate abruptly onto a horizontal floor. Two-component velocity and current density were measured with an ultrasonic Doppler velocity profiler and siphon sampler on the slope, just beyond the slope break and downstream on the horizontal floor. Three main factors influence longitudinal flow evolution and turbulence structure: sediment transport and sedimentation, slope angle, and the presence of a slope break. These controls interact differently depending on flow type. Sediment transport is accompanied by an inertial fluid reaction that enhances Reynolds stresses in turbidity flows. Thus turbidity flows mix more vigorously than equivalent saline density flows. For saline flows, turbulent kinetic energy is dependent on slope, and rapid deceleration occurs on the horizontal floor. For turbidity flows, normalized turbulent kinetic energy increases downstream, and mean streamwise deceleration is reduced compared with saline flows. The slope break causes mean bed-normal velocity of turbidity flows to become negative and have a gentler gradient compared with other locations. A reduction of peak Reynolds normal stress in the bed-normal direction is accompanied by an increase in turbulent accelerations across the rest of the flow thickness. Thus the presence of particles acts to increase Reynolds normal stresses independently of gradients of mean velocity, and sediment transport increases across the break in slope. The experiments illustrate that saline density currents may not be good dynamic analogues for natural turbidity currents