91,718 research outputs found

    Race and Policing: An Agenda for Action

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    This paper is organized into two parts -- Strategic Voice and Tactical Agency. Strategic Voice argues that problems of race in policing cannot be resolved by the police alone. Other people must help by understanding and ameliorating the social conditions that cause race to be associated with crime and hence become a dilemma for American policing. Rather than accepting these conditions as givens, police leaders with their powerful collective voice should actively call attention to what needs to be changed. Tactical Agency outlines what the police can do on their own initiative to deal with the operational dilemmas of race -- in the communities they serve and in their own organizations

    Utility based pricing and hedging of jump diffusion processes with a view to applications

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    We discuss utility based pricing and hedging of jump diffusion processes with emphasis on the practical applicability of the framework. We point out two difficulties that seem to limit this applicability, namely drift dependence and essential risk aversion independence. We suggest to solve these by a re-interpretation of the framework. This leads to the notion of an implied drift. We also present a heuristic derivation of the marginal indifference price and the marginal optimal hedge that might be useful in numerical computations.Comment: 23 pages, v2: publishe

    C.V.D. annual report: November 1965 research project RU27-1 :an analogue method for the determination of potential distributions in semiconductor systems

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    A general method for the solution of the nonlinear Shockley-Poisson differential equation which governs the potential distribution in non-degenerate semiconductor systems is described which can be applied to the evaluation of depletion layer widths, carrier densities and capacitance bias relationships of p-n junction structures. The method is based upon the use of a particular type of resistance network analogue and results obtained for several one and two dimensional configurations are discussed

    Explicit solution of an inverse first-passage time problem for L\'{e}vy processes and counterparty credit risk

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    For a given Markov process XX and survival function H\overline{H} on R+\mathbb{R}^+, the inverse first-passage time problem (IFPT) is to find a barrier function b:R+[,+]b:\mathbb{R}^+\to[-\infty,+\infty] such that the survival function of the first-passage time τb=inf{t0:X(t)<b(t)}\tau_b=\inf \{t\ge0:X(t)<b(t)\} is given by H\overline{H}. In this paper, we consider a version of the IFPT problem where the barrier is fixed at zero and the problem is to find an initial distribution μ\mu and a time-change II such that for the time-changed process XIX\circ I the IFPT problem is solved by a constant barrier at the level zero. For any L\'{e}vy process XX satisfying an exponential moment condition, we derive the solution of this problem in terms of λ\lambda-invariant distributions of the process XX killed at the epoch of first entrance into the negative half-axis. We provide an explicit characterization of such distributions, which is a result of independent interest. For a given multi-variate survival function H\overline{H} of generalized frailty type, we construct subsequently an explicit solution to the corresponding IFPT with the barrier level fixed at zero. We apply these results to the valuation of financial contracts that are subject to counterparty credit risk.Comment: Published at http://dx.doi.org/10.1214/14-AAP1051 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

    The Antebellum U.S. Iron Industry: Domestic Production and Foreign Competition

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    This paper presents new annual estimates of U.S. production of pig iron and imports of pig iron products dating back to 1827. These estimates are used to assess the vulnerability of the antebellum iron industry to foreign competition and the role of the tariff in fostering the industry's early development. Domestic pig iron production is found to be highly sensitive to changes in import prices. Although import price fluctuations had a much greater impact on U.S. production than changes in import duties, our estimates suggest that the tariff permitted domestic output to be about thirty to forty percent larger than it would have been without protection.

    Millimeter wavelength spectroscopy and continuum studies of the planets

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    Careful observations were made at 86.1 GHz to derive the absolute brightness temperatures of the Sun (7914 + or - 192 K), Venus (357.5 + or - 13.1 K), Jupiter (179.4 + or - 4.7K), and Saturn (153.4 + or - 4.8 K) with a standard error of about 3%. This is a significant improvement in accuracy over previous results. A stable transmitter and novel superheterodyne receiver were constructed and used to determine the effective collecting area of the MWO 4.9 m antenna relative to a previously calibrated standard gain horn. The thermal scale was set by calibrating the radiometer with carefully constructed and tested hot and cold loads. The brightness temperatures may be used to establish an absolute calibration scale and to determine the antenna aperture and beam efficiencies of other radio telescopes at 3.5 mm wavelength

    Arbitrage Bounds for Prices of Weighted Variance Swaps

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    We develop robust pricing and hedging of a weighted variance swap when market prices for a finite number of co--maturing put options are given. We assume the given prices do not admit arbitrage and deduce no-arbitrage bounds on the weighted variance swap along with super- and sub- replicating strategies which enforce them. We find that market quotes for variance swaps are surprisingly close to the model-free lower bounds we determine. We solve the problem by transforming it into an analogous question for a European option with a convex payoff. The lower bound becomes a problem in semi-infinite linear programming which we solve in detail. The upper bound is explicit. We work in a model-independent and probability-free setup. In particular we use and extend F\"ollmer's pathwise stochastic calculus. Appropriate notions of arbitrage and admissibility are introduced. This allows us to establish the usual hedging relation between the variance swap and the 'log contract' and similar connections for weighted variance swaps. Our results take form of a FTAP: we show that the absence of (weak) arbitrage is equivalent to the existence of a classical model which reproduces the observed prices via risk-neutral expectations of discounted payoffs.Comment: 25 pages, 4 figure

    Streaming velocities as a dynamical estimator of Omega

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    It is well known that estimating the pairwise velocity of galaxies, v_{12}, from the redshift space galaxy correlation function is difficult because this method is highly sensitive to the assumed model of the pairwise velocity dispersion. Here we propose an alternative method to estimate v_{12} directly from peculiar velocity samples, which contain redshift-independent distances as well as galaxy redshifts. In contrast to other dynamical measures which determine beta = sigma_8 x Omega^{0.6}, our method can provide an estimate of (sigma_8)^2 x Omega^{0.6} for a range of sigma_8 (here Omega is the cosmological mass density parameter while sigma_8 is the standard normalization parameter for the spectrum of matter density fluctuations). We demonstrate how to measure this quantity from realistic catalogues.Comment: 8 pages of text, 4 figures Subject headings: Cosmology: theory - observation - peculiar velocities: large scale flows Last name of one of the authors was misspelled. It is now corrected. Otherwise the manuscript is identical to its original versio
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