8,996 research outputs found
[Review of] James P. Comer, M. D. Maggie\u27s American Dream: The Life and Times of a Black Family
Maggie\u27s American Dream is a poignant story about the struggles and achievements of the Comer family from the early decades of the twentieth century to the present. Dr. Comer presents his family\u27s history through the use of side-by-side autobiographies, his mother\u27s and his own. The purpose of the book is to capture the vision and personal struggles of Comer\u27s mother, Maggie, and the efforts by her children to fulfill her and her husband Hugh\u27s goal to obtain a college education and pursue professional careers. The book begins with Maggie\u27s oral narrative, a collection of interviews that James had compiled over a three to four year period, in which she describes her growing-up years as the child of Mississippi sharecroppers and her eventual marriage to Hugh Comer, the son of an Alabama preacher
Fiber optic Raman thermometer for Space Shuttle main engine preburner profiling
The feasibility of combustion gas temperature measurements in the SSME fuel preburner using nonintrusive optical diagnostics was investigated. Temperature profiles are desired in the high pressure, hydrogen-rich preburner stream to evaluate designs to alleviate thermal stressing of the fuel pump turbine blades. Considering the preburner operating conditions and optical access restrictions, a spontaneous Raman backscattering system, implemented with optical fibers to couple to the combustion device, was selected as the most practical for gas temperature probing. A system is described which employs a remotely-located argon-ion laser to excite the molecular hydrogen Raman spectrum. The laser radiation is conveyed to the combustor through an optical fiber and focused through a window into the chamber by an optical head attached to the combustor. The gas temperature is determined from the distribution of rotational populations represented in the Raman spectrum
R&D Outsourcing Contract with Information Leakage
This paper studies an R&D outsourcing contract between a firm and a contractor, considereing the possibility that in the interim stage, the contractor might sell the innovation to the rival firm. Our result points out that due to the competition in the interim stage, the reward needed to prevent leakage will be pushed up to the extent that a profitable leakage free contract does not exist. This result will also apply to cases considering revenue-sharing schemes and a disclosure punishment for commercial theft. Then, we demonstrate that in a competitive mechanism where the R&D firm hires two contractors together with a relative performance scheme, the disclosure punishment might help and there exists a perfect Bayesian Nash equilibrium where the probability of information leakage is lower and the equilibrium reward is also cheaper than hiring one contractor.R&D outsourcing, Contract, Information leakage, Collusion, Multiple agents
Distribution of red deepsea crab (Chaceon quinquedens) by size and sex in the Gulf of Mexico
The red deepsea crab (Chaceon quinquedens (Smith, 1879)) has supported a commercial fishery off the coast of New England since the 1970s (Wigley et al., 1975) and has had
annual harvests from 400 metric tons (t) (1996) to 4000 t (2001) (NEFMC, 2002). In 2002, a fishery management plan for the northeast fishery on the Atlantic coast was implemented and total allowable catch was reduced to approximately 2500 t (NEFMC, 2002). Although there are management plans for the golden crab (C. fenneri) and the red deep sea crab for Atlantic coast regions, there is
no fishery management plan for red deepsea crabs in the Gulf of Mexico. Successful management for sustainable
harvests should be based on a knowledge of the life history of the species, but C. quinquedens has been a difficult species for which to obtain life history and abundance information because of its deep distribution
Bayesian Analysis of Structural Credit Risk Models with Microstructure Noises
In this paper a Markov chain Monte Carlo (MCMC) technique is developed for the Bayesian analysis of structural credit risk models with microstructure noises. The technique is based on the general Bayesian approach with posterior computations performed by Gibbs sampling. Simulations from the Markov chain, whose stationary distribution converges to the posterior distribution, enable exact finite sample inferences of model parameters. The exact inferences can easily be extended to latent state variables and any nonlinear transformation of state variables and parameters, facilitating practical credit risk applications. In addition, the comparison of alternative models can be based on devian information criterion (DIC) which is straightforwardly obtained from the MCMC output. The method is implemented on the basic structural credit risk model with pure microstructure noises and some more general specifications using daily equity data from US and emerging markets. We find empirical evidence that microstructure noises are positively correlated with the firm values in emerging markets.MCMC, Credit risk, Microstructure noise, Devian information criterion
Theoretical optical and x-ray spectra of liquid and solid H_2O
Theoretical optical and x-ray spectra of model structures of water and ice
are calculated using a many-body perturbation theory, Bethe-Salpeter equation
(BSE) approach implemented in the valence- and core-excitation codes AI2NBSE
and OCEAN. These codes use ab initio density functional theory wave functions
from a plane-wave, pseudopotential code, quasi-particle self energy
corrections, and a BSE treatment of particle-hole interactions. The approach
improves upon independent-particle methods through the inclusion of a complex,
energy-dependent self energy and screened particle-hole interactions to account
for inelastic losses and excitonic effects. These many-body effects are found
to be crucial for quantitative calculations of ice and water spectra
MUSTANG 3.3 Millimeter Continuum Observations of Class 0 Protostars
We present observations of six Class 0 protostars at 3.3 mm (90 GHz) using
the 64-pixel MUSTANG bolometer camera on the 100-m Green Bank Telescope. The
3.3 mm photometry is analyzed along with shorter wavelength observations to
derive spectral indices (S_nu ~ nu^alpha) of the measured emission. We utilize
previously published dust continuum radiative transfer models to estimate the
characteristic dust temperature within the central beam of our observations. We
present constraints on the millimeter dust opacity index, beta, between 0.862
mm, 1.25 mm, and 3.3 mm. Beta_mm typically ranges from 1.0 to 2.4 for Class 0
sources. The relative contributions from disk emission and envelope emission
are estimated at 3.3 mm. L483 is found to have negligible disk emission at 3.3
mm while L1527 is dominated by disk emission within the central beam. The
beta_mm^disk <= 0.8 - 1.4 for L1527 indicates that grain growth is likely
occurring in the disk. The photometry presented in this paper may be combined
with future interferometric observations of Class 0 envelopes and disks.Comment: 19 pages, 3 figures, AJ accepted, in pres
Bethe-Salpeter Equation Calculations of Core Excitation Spectra
We present a hybrid approach for GW/Bethe-Salpeter Equation (BSE)
calculations of core excitation spectra, including x-ray absorption (XAS),
electron energy loss spectra (EELS), and non-resonant inelastic x-ray
scattering (NRIXS). The method is based on {\it ab initio} wavefunctions from
the plane-wave pseudopotential code ABINIT; atomic core-level states and
projector augmented wave (PAW) transition matrix elements; the NIST core-level
BSE solver; and a many-pole GW self-energy model to account for final-state
broadening and self-energy shifts. Multiplet effects are also accounted for.
The approach is implemented using an interface dubbed OCEAN (Obtaining Core
Excitations using ABINIT and NBSE). To demonstrate the utility of the code we
present results for the K-edges in LiF as probed by XAS and NRIXS, the K-edges
of KCl as probed by XAS, the Ti L_2,3-edge in SrTiO_3 as probed by XAS, and the
Mg L_2,3-edge in MgO as probed by XAS. We compare the results to experiments
and results obtained using other theoretical approaches
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