Research and education in management of large- scale technical programs Semiannual progress report

Research and education in management of large scale technical programs - education and integration of interdisciplinary tea

Technology and management of large-scale programs Semiannual progress report

Technology and management of large scale program

The preparation, identification and properties of chlorophyll derivatives

In the investigation of 10-hydroxy chlorophylls a and b novel techniques included modification of chromatography and the use of fully-deuterated compounds isolated from fully-deuterated autotropic algae to determine the molecular structure of the chlorophylls

State and Local Anti-Predatory Lending Laws: The Effect of Legal Enforcement Mechanisms

Subprime mortgage lending has grown rapidly in recent years and with it, so have concerns about predatory lending. In response to evidence of predatory lending, most states have enacted new laws or expanded existing laws to address abuses in the subprime home loan market. The effect of these statutes is a matter of debate. This paper seeks to improve the understanding of this increasingly important issue and pays particular attention to the role that legal enforcement mechanisms play in this context. The results of the analysis are consistent with the view that anti-predatory lending laws influence subprime lending markets and that disaggregating the details of the overall legal framework into its component parts is essential for understanding subprime market dynamics. The restrictions, coverage, and enforcement components all have significant relationships with subprime market outcomes, with the coverage relationship found to be broadly consistent with the reverse lemons hypothesis put forward by Ho and Pennington-Cross (2007). The results also suggest that the newer mini-HOEPA laws have had an impact on the subprime market above and beyond the older preexisting laws, particularly for subprime originations. Broader coverage through these new laws is associated with higher origination likelihoods, while increased restrictions through the mini-HOEPA laws are associated with lower origination propensities

The Impact of State Anti-Predatory Lending Laws: Policy Implications and Insights

The subprime mortgage market, which consists of high-cost loans designed for borrowers with weak credit, has grown tremendously over the past ten years. Between 1993 and 2005, the subprime market experienced an average annual growth rate of 26 percent. As this market emerged, so did allegations that subprime loans contained predatory features or were the result of predatory sales practices.3 In the worst cases, brokers deceived borrowers about the meaning of loan terms or falsely promised to assist them in obtaining future refinance loans with better terms. In other situations, borrowers entered into loans with low teaser rates, not aware how high their monthly payments could go when their interest rates reset

Research and education in management of large-scale technical programs

A research effort is reported which was conducted by NASA in conjunction with Drexel University, and which was aimed at an improved understanding of large scale systems technology and management

NMR relaxation rates for the spin-1/2 Heisenberg chain

The spin-lattice relaxation rate $1/T_1$ and the spin echo decay rate $1/T_{2G}$ for the spin-$1\over 2$ antiferromagnetic Heisenberg chain are calculated using quantum Monte Carlo and maximum entropy analytic continuation. The results are compared with recent analytical calculations by Sachdev. If the nuclear hyperfine form factor $A_q$ is strongly peaked around $q=\pi$ the predicted low-temperature behavior [$1/T_1 \sim \ln{^{1/2}(1/T)}$, $1/T_{2G} \sim \ln{^{1/2}(1/T)}/\sqrt{T}$] extends up to temperatures as high as $T/J \approx 0.5$. If $A_q$ has significant weight for $q \approx 0$ there are large contributions from diffusive long-wavelength processes not taken into account in the theory, and very low temperatures are needed in order to observe the asymptotic $T \to 0$ forms.Comment: 9 pages, Revtex 3.0, 5 uuencoded ps figures To appear in Phys. Rev. B, Rapid Com

The dispersive contribution of ρ(1450,1700)\rho(1450,1700) decays and X(1576)

We study whether the broad enhancement X(1576) arises from the final state interaction (FSI) of $\rho(1450,1700)\to \rho^+\rho^-\to K^{+}K^{-}$ decays. We consider both the absorptive and dispersive contribution of the above amplitudes since the intermediate states are very close to $\rho(1450,1700)$. The same mechanism leads to a similar enhancement around 1580 MeV in the $\pi^{+}\pi^-$ spectrum in the $J/\psi\to \pi^{0}\pi^{+}\pi^{-}$ channel, which can be used to test whether X(1576) can be ascribed to the FSI effect of $\rho(1450,1700)\to \rho^+\rho^-$.Comment: 4 pages, 4 figure

Spin dynamics of SrCu2_2O3_3 and the Heisenberg ladder

The $S=1/2$ Heisenberg antiferromagnet in the ladder geometry is studied as a model for the spin degrees of freedom of SrCu$_2$O$_3$. The susceptibility and the spin echo decay rate are calculated using a quantum Monte Carlo technique, and the spin-lattice relaxation rate is obtained by maximum entropy analytic continuation of imaginary time correlation functions. All calculated quantities are in reasonable agreement with experimental results for SrCu$_2$O$_3$ if the exchange coupling $J \approx 850$K, i.e. significantly smaller than in high-T$_c$ cuprates.Comment: 11 pages (Revtex) + 3 uuencoded ps files. To appear in Phys. Rev. B, Rapid Com