Welfare Reform and Food Stamp Caseload Dynamics

We use state-level panel data for federal fiscal years 1980–1998 to estimate the impacts of welfare reform and the business cycle on food stamp caseloads. The model we employ is a dynamic function of past caseloads, economic factors, AFDC and Food Stamp Program policies, political factors, AFDC caseload levels, and unobserved fixed and trending heterogeneity. Our results suggest that the robust economy has substantially influenced the recent decline in food stamp caseloads, but that the estimated aggregate effect of welfare reform is modest—we attribute around 45 percent of 1994–1998 decline to the macroeconomy and about 5 percent to welfare reform. We do find substantial heterogeneity in the impact of AFDC waiver policies. States with JOBS sanctions policies but not family cap or earnings disregard waivers can expect a larger long-run decline in caseloads than those states with all three policies. In addition, we do find some evidence, albeit weaker, that states with waivers for unemployed able-bodied adults without dependents can expect higher caseload levels than states without the waivers and that the Electronic Benefits Transfer program is leading to food stamp caseload declines. An important finding of this study is that modeling food stamp caseload dynamics has implications for the estimated effects of policy changes and economic factors—when dynamic models are employed, we observe substantially reduced welfare-reform effects but significantly increased effects of the macroeconomy on food stamp caseloads. These results are robust to models that permit the simultaneous determination of AFDC and food stamp caseloads.

Project for the analysis of technology transfer Quarterly report, 1 Oct. - 31 Dec. 1969

Analysis of Tech Brief-Technical Support Package progra

Relative selectivity in trawls, longline and gillnets on Greenland halibut

Gear selection and sampling gears. Proceedings of the seventh IMR-PINRO Symposium. Murmansk, 23-24 June 1997.Selectivity parameters for Greenland halibut (Reinhardtius hippoglossoides, Walbaum) are compared to catches reported fiom trawl, gillnets and longline in the Norwegian scientific fisheries for Greenland halibut. A trouser trawl selectivity experiment reported here gives an L50 at 43 cm in 135 mm codend. A selectivity analysis of the gillnets using loglinear models is done, and show maximum retention probability for lengths at 40.6 - 63.8 cm for the five mesh-sizes used. The effect of the fishiig strategy is analysed in respect to the selectivity of the gear used and the diskibution of length and age in the catches. To avoid possible bias from strong dominating yearclasses and selection in these comparisons, length-at-age data are used. The sex-ratio in gillnet catches is shown to be a linear fiinction of meshsize. Our data show no trend in length distribution with depth. We show that calculated growth of female Greenland halibut is affected by the selectivity of the gears. It is shown that growth parameters calculated fiom gillnet catches may be biased due to the selection properties in the gillnets. These analyses will provide a better understanding of possible sarnpling bias when sampling a stock with only one gear

The Price Responsiveness of Shale Producers: Evidence from Micro Data

We show that shale oil producers respond positively to favourable oil price signals, and that this response is mainly associated with the timing of production decisions through well completion and refracturing, consistent with the Hotelling theory of optimal extraction. This finding is established using a novel proprietary data set consisting of more than 200,000 shale wells across ten U.S. states spanning almost two decades. We document large heterogeneity in the estimated responses across the various shale wells, suggesting that aggregation bias is an important issue for this kind of analysis. Our empirical results call for new models that can account for a growing share of shale oil in the U.S., the inherent flexibility of shale extraction technology in production and the role of shale oil in transmitting oil price shocks to the global economy.publishedVersio

COMPASS: a 2.6m telescope for CMBR polarization studies

COMPASS (COsmic Microwave Polarization at Small Scale) is an experiment devoted to measuring the polarization of the CMBR. Its design and characteristics are presented

A Limit on the Polarized Anisotropy of the Cosmic Microwave Background at Subdegree Angular Scales

A ground-based polarimeter, PIQUE, operating at 90 GHz has set a new limit on the magnitude of any polarized anisotropy in the cosmic microwave background. The combination of the scan strategy and full width half maximum beam of 0.235 degrees gives broad window functions with average multipoles, l = 211+294-146 and l = 212+229-135 for the E- and B-mode window functions, respectively. A joint likelihood analysis yields simultaneous 95% confidence level flat band power limits of 14 and 13 microkelvin on the amplitudes of the E- and B-mode angular power spectra, respectively. Assuming no B-modes, a 95% confidence limit of 10 microkelvin is placed on the amplitude of the E-mode angular power spectrum alone.Comment: 4 pages, 3 figures, submitted to Astrophysical Journal Letter

On the eigenproblems of PT-symmetric oscillators

We consider the non-Hermitian Hamiltonian H= -\frac{d^2}{dx^2}+P(x^2)-(ix)^{2n+1} on the real line, where P(x) is a polynomial of degree at most n \geq 1 with all nonnegative real coefficients (possibly P\equiv 0). It is proved that the eigenvalues \lambda must be in the sector | arg \lambda | \leq \frac{\pi}{2n+3}. Also for the case H=-\frac{d^2}{dx^2}-(ix)^3, we establish a zero-free region of the eigenfunction u and its derivative u^\prime and we find some other interesting properties of eigenfunctions.Comment: 21pages, 9 figure

Temperature inversion symmetry in the Casimir effect with an antiperiodic boundary condition

We present explicitly another example of a temperature inversion symmetry in the Casimir effect for a nonsymmetric boundary condition. We also give an interpretation for our result.Comment: 4 page