Global rainfall monitoring by SSM/I

Significant accomplishments in the last year of research are presented. During 1991, three main activities were undertaken: (1) development and testing of a preliminary global rainfall algorithm; (2) researching areas of strong surface scattering; and (3) formulation of a program of work for the WetNet PrecipWG. Focus of present research and plans for next year are briefly dismissed

The Complex Links Between Governance and Biodiversity

We argue that two problems weaken the claims of those who link corruption and the exploitation of natural resources. The first is conceptual. Studies that use national level indicators of corruption fail to note that corruption comes in many forms, at multiple levels, and may or may not affect resource use. Without a clear causal model of the mechanism by which corruption affects resources, one should treat with caution any estimated relationship between corruption and the state of natural resources. The second problem is methodological: Simple models linking corruption measures and natural resource use typically do not account for other important causes and control variables pivotal to the relationship between humans and natural resources. By way of illustration of these two general concerns, we demonstrate that the findings of a well known recent study that posits a link between corruption and decreases in forests, elephants, and rhinoceros are fragile to simple conceptual and methodological refinements

Test of shell-model interactions for nuclear structure calculations

The binding energy and excitation spectra of 6Li are calculated in a no-core shell-model space giving encouraging results. The results of this calculation are then treated as a theoretical experiment, against which different effective-interaction approximations are compared. In this way insight into the perturbation expansion for the effective interaction is obtained

Evaluating the success of seed sowing in a New England grassland

Grassland habitat is declining in the northeastern United States, leading to a decline in associated native species. Consequently, there is considerable interest by land managers in conserving and restoring grassland habitats in the Northeast. However, unlike the Great Plains and Europe, quantitative monitoring of restoration sites is uncommon, making it difficult to improve new restoration projects. Here we evaluate a grassland restoration in Waterford, Connecticut to determine if mechanical clearing of woody vegetation combined with sowing 23 native grasses and forbs led to successful establishment of these species. We also compared cover, diversity, and colonization by exotic and woody species in planted and unplanted areas over time. In the third and fifth growing seasons after planting in 2006, we sampled the vegetation in the planted site, an unplanted zone within the planted grassland, and an adjacent unplanted grassland. Twenty of the 23 sown species established by 2010, and sown species dominated the planted area (70% of total cover). Despite the successful establishment of most sown species, species richness and diversity were no higher in the sown grassland than in adjacent unseeded areas. However, the sown grassland contained lower cover of non-native and invasive species. Big bluestem (Andropogon gerardii Vitman) established aggressively, potentially reducing both exotic colonization and native diversity. This study shows that sowing native grassland species can lead to the successful development of native-dominated grasslands. Results can inform future grassland restoration efforts in the Northeast and show that seeding with aggressive grass species may greatly impact restored plant communities

Asymptotics of Relativistic Spin Networks

The stationary phase technique is used to calculate asymptotic formulae for SO(4) Relativistic Spin Networks. For the tetrahedral spin network this gives the square of the Ponzano-Regge asymptotic formula for the SU(2) 6j symbol. For the 4-simplex (10j-symbol) the asymptotic formula is compared with numerical calculations of the Spin Network evaluation. Finally we discuss the asymptotics of the SO(3,1) 10j-symbol.Comment: 31 pages, latex. v3: minor clarification

Population inversion of driven two-level systems in a structureless bath

We derive a master equation for a driven double-dot damped by an unstructured phonon bath, and calculate the spectral density. We find that bath mediated photon absorption is important at relatively strong driving, and may even dominate the dynamics, inducing population inversion of the double dot system. This phenomenon is consistent with recent experimental observations.Comment: 4 Pages, Added Reference [30] to Dykman, 1979, available at http://www.pa.msu.edu/people/dykman/pub/Sov.J.LowTemp.Phys_5.pd

Universality of Decay out of Superdeformed Bands in the 190 Mass Region

Superdeformed nuclei in the 190 mass region exhibit a striking universality in their decay-out profiles. We show that this universality can be explained in the two-level model of superdeformed decay as related to a strong separation of energy scales: a higher scale related to the nuclear interactions, and a lower scale caused by electromagnetic decay. Furthermore, we present the results of the two-level model for all decays for which sufficient data are known, including statistical extraction of the matrix element for tunneling through the potential barrier.Comment: 7 pages, 3 figures. v2: some minor clarifications, minor correction to Fig.

Development and evaluation of a device to simulate a sonic boom

A device to simulate the vibrational and acoustical properties of a sonic boom was developed and evaluated. The design employed a moving circular diaphragm which produced pressure variations by altering the volume of an air-tight enclosure that was located adjacent to an acoustical test chamber. A review of construction oriented problems, along with their solutions, is presented. The simulator is shown to produce the effects of sonic booms having pressure signatures with rise times as low as 5 milliseconds, durations as short as 80 milliseconds, and overpressures as high as 2.5 pounds per square foot. Variations in the signatures are possible by independent adjustments of the simulator. The energy spectral density is also shown to be in agreement with theory and with actual measurements for aircraft