Human Capital and Earnings Distribution Dynamics

Mean earnings and measures of earnings dispersion and skewness all increase in US data over most of the working life-cycle for a typical cohort as the cohort ages. We show that a benchmark human capital model can replicate these properties from the right distribution of initial human capital and learning ability. These distributions have the property that learning ability must differ across agents and that learning ability and initial human capital are positively correlated.

Julia Thecla: Undiscovered Worlds

https://via.library.depaul.edu/museum-publications/1004/thumbnail.jp

On quasi-local charges and Newman--Penrose type quantities in Yang--Mills theories

We generalize the notion of quasi-local charges, introduced by P. Tod for Yang--Mills fields with unitary groups, to non-Abelian gauge theories with arbitrary gauge group, and calculate its small sphere and large sphere limits both at spatial and null infinity. We show that for semisimple gauge groups no reasonable definition yield conserved total charges and Newman--Penrose (NP) type quantities at null infinity in generic, radiative configurations. The conditions of their conservation, both in terms of the field configurations and the structure of the gauge group, are clarified. We also calculate the NP quantities for stationary, asymptotic solutions of the field equations with vanishing magnetic charges, and illustrate these by explicit solutions with various gauge groups.Comment: 22 pages, typos corrected, appearing in Classical and Quantum Gravit

On asymptotically flat solutions of Einstein's equations periodic in time II. Spacetimes with scalar-field sources

We extend the work in our earlier article [4] to show that time-periodic, asymptotically-flat solutions of the Einstein equations analytic at scri, whose source is one of a range of scalar-field models, are necessarily stationary. We also show that, for some of these scalar-field sources, in stationary, asymptotically-flat solutions analytic at scri, the scalar field necessarily inherits the symmetry. To prove these results we investigate miscellaneous properties of massless and conformal scalar fields coupled to gravity, in particular Bondi mass and its loss.Comment: 29 pages, published in Class. Quant. Grav. Replaced. Typos corrected, version which appeared in Class. Quant.Gra

Hepatitis B surface antigen in urine of hemodialysis patients

Hepatitis B surface antigen in urine of hemodialysis patients. As part of an extensive epidemiological survey of chronic hemodialysis patients in Michigan, hepatitis B surface antigen (HBsAg) was identified in the sera of 79 of 701 (11%) patients. Of these patients, 59 were carriers of HBsAg for three or more months. Urine samples were collected from 36 of 39 HBsAg carriers having urinary output. Of these samples, 19 (52%) were positive for HBsAg by radioimmunoassay; this was confirmed by specific antibody neutralization. The HBsAg was not identified in the urine of seven hemodialysis patients who were lacking serum HBsAg or in urine samples from three HBsAg sero-carriers who had normal renal function. Patients undergoing maintenance hemodialysis appear to constitute a large reservoir of HBsAg chronic carriers. This study indicates that a minimum of 50% of persistent HBsAg carriers who are producing urine have detectable. HBsAg in single, randomly timed, unconcentrated urine specimen. These data suggest that urine may represent a potential vehicle for transmission in nonparenterally acquired hepatitis B.Antigène de surface de l'hépatite B dans l'urine de malades en hémodialyse. Dans le cadre d'une large enquête épidémiologique à propos des malades en hémodialyse chronique dans le Michigan, l'antigène de surface de l'hépatite B (HBsAg) a été identifié dans le sérum de 79 parmi 701 malades (11%). Parmi ces malades, 59 étaient des porteurs de HBsAg depuis 3 mois ou plus. L'urine de 36 des 39 porteurs de HBsAg, qui avaient une diurèse, a été recueillie. Parmi ces 36 urines, 19 (52%) sont positives pour HBsAg par radio-immunologie, ce qui est confirmé par la neutralisation au moyen d'anticorps spécifique. Le HBsAg n'apas été identifié dans l'urine de 7 malades en hémodialyse qui n'avaient pas le HBsAg sérique et dans l'urine de 3 porteurs de HBsAg dont les fonctions rénales étaient normales. Les malades soumis à l'hémodialyse itérative paraissent constituer un grand réservoir de porteurs chroniques de HBsAg. Cette étude indique qu'au minimum 50% des porteurs chroniques de HBsAg qui ont une diurèse, ont un HBsAg détectable dans un échantillon unique d'urine, prélevé au hasard, non concentré. Ces résultats suggèrent que l'urine peut être un véhicule de transmission de l'hépatite B acquise par voie non parentérale

A Structure of Restricted Boltzmann Machine for Modeling System Dynamics

International audienceThis paper presents a new approach for learning transition function in state representation learning (SRL) for control. While state-of-the-art methods use different deterministic neural networks to learn forward and inverse state transition functions independently with auto-supervised learning, we introduce a bidirectional stochastic model to learn both transition functions. We aim at using the uncertainty of the model on its predictions as an intrinsic motivation for exploration to enhance the representation learning. More, using the same model to learn both transition functions allows sharing the parameters, which can reduce their number and should increase the embedding quality of the representation. We use a factored restricted Boltzmann machine (fRBM) based model, enhanced with dedicated structure for learning system dynamics and transitions with shared parameters. The presented work focuses on building the structure of the bidirectional transition model for unsupervised learning. Our fRBM structure is directly inspired from physics interactions between inputs and outputs in reinforcement learning framework. We compare different training algorithms for learning the model that must be able to predict observable random variables to be used in SRL framework. Our structure is not restricted to any type of observable, nevertheless in this paper we focus on learning dynamics from the OpenAI Gym environment Swinging Pendulum. We show that the proposed structure is able to learn bidirectional transition function and performs well in prediction task

Two dimensional Sen connections and quasi-local energy-momentum

The recently constructed two dimensional Sen connection is applied in the problem of quasi-local energy-momentum in general relativity. First it is shown that, because of one of the two 2 dimensional Sen--Witten identities, Penrose's quasi-local charge integral can be expressed as a Nester--Witten integral.Then, to find the appropriate spinor propagation laws to the Nester--Witten integral, all the possible first order linear differential operators that can be constructed only from the irreducible chiral parts of the Sen operator alone are determined and examined. It is only the holomorphy or anti-holomorphy operator that can define acceptable propagation laws. The 2 dimensional Sen connection thus naturally defines a quasi-local energy-momentum, which is precisely that of Dougan and Mason. Then provided the dominant energy condition holds and the 2-sphere S is convex we show that the next statements are equivalent: i. the quasi-local mass (energy-momentum) associated with S is zero; ii.the Cauchy development $D(\Sigma)$ is a pp-wave geometry with pure radiation ($D(\Sigma)$ is flat), where $\Sigma$ is a spacelike hypersurface whose boundary is S; iii. there exist a Sen--constant spinor field (two spinor fields) on S. Thus the pp-wave Cauchy developments can be characterized by the geometry of a two rather than a three dimensional submanifold.Comment: 20 pages, Plain Tex, I

Witten spinors on maximal, conformally flat hypersurfaces

The boundary conditions that exclude zeros of the solutions of the Witten equation (and hence guarantee the existence of a 3-frame satisfying the so-called special orthonormal frame gauge conditions) are investigated. We determine the general form of the conformally invariant boundary conditions for the Witten equation, and find the boundary conditions that characterize the constant and the conformally constant spinor fields among the solutions of the Witten equations on compact domains in extrinsically and intrinsically flat, and on maximal, intrinsically globally conformally flat spacelike hypersurfaces, respectively. We also provide a number of exact solutions of the Witten equation with various boundary conditions (both at infinity and on inner or outer boundaries) that single out nowhere vanishing spinor fields on the flat, non-extreme Reissner--Nordstr\"om and Brill--Lindquist data sets. Our examples show that there is an interplay between the boundary conditions, the global topology of the hypersurface and the existence/non-existence of zeros of the solutions of the Witten equation.Comment: 23 pages, typos corrected, final version, accepted in Class. Quantum Gra