The Diffusion of Informal Knowledge and Innovation Performance: A sectoral approach

This paper tries to quantify the effect of diffusion of informal knowledge on the innovative performance of European firms using data derived from the 3rd Community Innovation Survey. When firms are asked whether or not they have introduced new products or processes, they were also asked to which degree such innovations were developed in-house. These degrees were captured by the CIS variables InPdtW and InPcsW. These variables ranged from 1 (Mainly done by the firm) to 3 (Mainly done by other enterprises). The focus of this paper is to investigate the impact of diffusion of informal knowledge. We combine the previous variables with another variable which reflects firms that were not doing any formal collaboration with other institutions. If an innovative firm has no formal collaboration arrangements and the innovation has not been done mainly by the firm, then diffusion of informal knowledge is considered to be the main driver of the innovation. The idea is that informal channels are accessible to all firms. This paper tries to quantify the impact of such flows of knowledge on firms' innovation performance. To do this, a two step procedure is followed: -In a first step, a latent variable for diffusion of informal knowledge is defined and estimated based on firms' characteristics. -In a second step, the latent diffusion variable is introduced as a regressor in a probit/tobit model.Knowledge flows, innovation, dynamic equations, sectoral innovation, CIS

Stabilization of solitons of the multidimensional nonlinear Schrodinger equation: Matter-wave breathers

We demonstrate that stabilization of solitons of the multidimensional Schrodinger equation with a cubic nonlinearity may be achieved by a suitable periodic control of the nonlinear term. The effect of this control is to stabilize the unstable solitary waves which belong to the frontier between expanding and collapsing solutions and to provide an oscillating solitonic structure, some sort of breather-type solution. We obtain precise conditions on the control parameters to achieve the stabilization and compare our results with accurate numerical simulations of the nonlinear Schrodinger equation. Because of the application of these ideas to matter waves these solutions are some sort of matter breathers

On the White Dwarf distances to Galactic Globular Clusters

We analyze in detail various possible sources of systematic errors on the distances of globular clusters derived by fitting a local template DA white dwarf sequence to the cluster counterpart (the so-called WD-fitting technique). We find that the unknown thickness of the hydrogen layer of white dwarfs in clusters plays a non negligible role. For reasonable assumptions - supported by the few sparse available observational constraints - about the unknown mass and thickness of the hydrogen layer for the cluster white dwarfs, a realistic estimate of the systematic error on the distance is within +-0.10 mag. However, particular combinations of white dwarf masses and envelope thicknesses - which at present cannot be excluded a priori - could produce larger errors. Contamination of the cluster DA sequence by non-DA white dwarfs introduces a very small systematic error of about -0.03 mag in the Mv/(V-I) plane, but in the Mv/(B-V) plane the systematic error amounts to ~ +0.20 mag. Contamination by white dwarfs with helium cores should not influence appreciably the WD-fitting distances. Finally, we obtain a derivative D((m-M)v)/D(E(B-V))~ -5.5 for the WD-fitting distances, which is very similar to the dependence found when using the Main Sequence fitting technique.Comment: 12 pages, 11 figures A&A, accepted for publicatio

Axions and White Dwarfs

White dwarfs are almost completely degenerate objects that cannot obtain energy from the thermonuclear sources and their evolution is just a gravothermal process of cooling. The simplicity of these objects, the fact that the physical inputs necessary to understand them are well identified, although not always well understood, and the impressive observational background about white dwarfs make them the most well studied Galactic population. These characteristics allow to use them as laboratories to test new ideas of physics. In this contribution we discuss the robustness of the method and its application to the axion case.Comment: 4 pages, 1 figure, to appear in the Proceedings for the 6th Patras meeting on Axions, WIMPs and WISP

FLOW DYNAMICS IN THE TRANSITION ZONE FROM ESTUARINE TIDAL TO FLUVIAL REGIME IN THE SANTEE RIVER, SC, USA

Estuaries are important systems that link fresh, inland waters to oceanic salt water, where they act to deliver large amounts of nutrients, sediments and pollutants into the ocean. Traditionally, the study of estuarine systems has been marked by difficulty owing to the complex hydrodynamics influenced by strong bathymetric changes, changes in tidal range, intricate geomorphology, among other factors; thus beginning to unravel the complexities of estuarine hydrodynamics will help to illuminate the nature of estuaries as well as to provide a foundation for their further study. In this study I focus on the transition zone from tidal to fluvial regime, which is defined as an area where tidal and river discharges are comparable. Recently, the transition zone has been the focus of attention as an important region within an estuary. Tides are subject to frictional dissipation as they propagate inland through estuaries and river channels. Previous studies suggest that there is an enhanced tidal dissipation in the transition zone from a tidal to fluvial regime when the tidal flux and river discharge become comparable. The aim of this study is to understand the kinematics and dynamics within the transition zone. In particular, I hypothesize that there is an enhanced tidal dissipation in the transition zone due to (i) additive effects of tidal and river currents subject to the quadratic bottom friction, and (ii) to the presence of variable topography and enhanced bathymetric gradients in the transition zone. I analyzed time series of velocity profiles and bottom pressure that resolve the along-channel depth-averaged momentum balance in the transition zone of the Santee River, SC, USA. The following momentum balance terms are estimated: inertia (local acceleration), along-channel advective acceleration, pressure gradient, and bottom friction terms. Instruments were deployed in a 1-km long river reach characterized by a decreasing depth in the upstream direction from over 4 m to less than 2 m. Tides in the study area are predominantly semi-diurnal, flood-dominant. The leading terms in the depth-averaged momentum balance are found to be inertia, pressure gradient, and bottom friction. The pressure gradient and inertia dominate the momentum balance during the flood and subsequent current reversal from flood to ebb. However, during the ebb the pressure gradient is nearly balanced by bottom friction. A dissipative term is defined as a residual of inertia, advection, and pressure gradient force terms. I found that the dissipative term is comparable with the bottom friction term under steady river discharge. However, the bottom friction term underestimates the dissipative term when the river discharge exhibits abrupt variations. This yields a record-mean with a linear regression slope of 0.54. I hypothesize that the lateral eddy viscosity also contributes to tidal dissipation, especially when the pressure gradient force increases. Although tides are flood-dominant, most of the dissipation occurs during the ebb due to a superposition of comparable fluvial and tidal currents

Precision radiative corrections to the Dalitz plot of baryon semileptonic decays including the spin-momentum correlation of the decaying baryon and the emitted charged lepton

We calculate the radiative corrections to the angular correlation between the polarization of the decaying baryon and the direction of the emitted charged lepton in the semileptonic decays of spin one-half baryons to order (\alpha/\pi)(q/M_1). The final results are presented, first, with the triple integration of the bremsstrahlung photon ready to be performed numerically and, second, in an analytical form. A third presentation of our results in the form of numerical arrays of coefficients to be multiplied on the quadratic products of form factors is discussed. This latter may be the most practical one to use in Monte Carlo simulations. A series of crosschecks is performed. The results are useful in the analysis of the Dalitz plot of precision experiments involving light and heavy quarks and is not compromised to fixing the form factors at predetermined values. It is assumed that the real photons are kinematically discriminated. Otherwise, our results have a general model-independent applicability.Comment: 8 pages, RevTex4, 5 tables, no figures. Shortened version; results and conclusions remain unchange