A MICROCOMPUTER LINEAR PROGRAMMING PACKAGE: AN ALTERNATIVE TO MAINFRAMES

This paper presents the capabilities and limitations of a microcomputer linear programming package. The solution algorithm is a version of the revised simplex. Rapid problem entry, user ease of operation, sensitivity analyses on objective function and right hand sides are advantages. A problem size of 150 activities and 64 constraints can be solved in present form. Due to problem size, limitations and lack of parametric and integer programming routines, this package is thought to have the most value in teaching applications and research problems in the smaller size categories.Research and Development/Tech Change/Emerging Technologies,

In Situ Formation and Dynamical Evolution of Hot Jupiter Systems

Hot Jupiters, giant extrasolar planets with orbital periods shorter than ~10 days, have long been thought to form at large radial distances, only to subsequently experience long-range inward migration. Here, we propose that in contrast with this picture, a substantial fraction of the hot Jupiter population formed in situ via the core accretion process. We show that under conditions appropriate to the inner regions of protoplanetary disks, rapid gas accretion can be initiated by Super-Earth type planets, comprising 10-20 Earth masses of refractory composition material. An in situ formation scenario leads to testable consequences, including the expectation that hot Jupiters should frequently be accompanied by additional low-mass planets with periods shorter than ~100 days. Our calculations further demonstrate that dynamical interactions during the early stages of planetary systems' lifetimes should increase the inclinations of such companions, rendering transits rare. High-precision radial velocity monitoring provides the best prospect for their detection.Comment: 19 pages, 10 figures, accepted to Ap

Inventory and Analysis of Plankton in Green River within Mammoth Cave National Park

National Park Service biological staff are charged with preserving and protecting all creatures within a park’s boundaries. It is only a matter of time before exotic zebra mussels (Dreissena polymorpha) invade all eastern waterways including Green River within Mammoth Cave National Park, Kentucky. The National Park Service, in cooperation with University of Tennessee, initiated this inventory of plankton within Mammoth Cave National Park to establish baseline data prior to zebra mussel invasion. During this two year study (2000-2002), 180 plankton samples were collected at three sampling sites which encompassed all major riverine habitat types within the three flow zones (free-flow, transitional, impounded) created by Lock and Dam #6. Duplicate plankton samples were taken on all six occasions at these sites. Each year one sample was collected in June/July (base flow), another in August/September (base flow), and the other in November/December (enhanced flow). Zooplankton were sampled using both vertical (4/site) and horizontal (4/site) tows with 153-micron and 80-micron mesh plankton nets. Samples were fixed in the field with a 10% sugared formalin solution for later examination in the laboratory. A 1.0-L polycarbonate water bottle was used to collect phytoplankton samples at a depth just above the Secchi disk transparency level; samples were fixed in a 1% Lugol’s solution and stored in an opaque container for analysis. Water temperature, conductivity, dissolved oxygen, pH, and water transparency were also measured and recorded at each sample site. Water quality data were similar among sites and the variation among dates was consistent with climatic conditions. Dissolved oxygen ranged from 10.96 (mg/L) in iv December 2001 to 6.20 (mg/L) in July 2002. Temperature ranged from 25.9o C in July 2002 to 6.4o C in November 2000. The pH ranged from 8.05 (su) in November 2000 to 5.72 (su) in July 2002. Conductivity ranged from 282 (mS/cm) in November 2000 to 383 (mS/cm) in July 2002. A paucity of zooplankton was observed in Green River while phytoplankton densities were similar to levels measured upstream in Green River Lake. The dominant zooplankton groups were Cladocera (Bosmina longirostrus) and Copepoda (Mesocyclops edax). Densities of Bosmina ranged from 0.01/L in September 2000 to 0.46/L in December 2001; M. edax densities ranged from 0.01/L to 0.53/L during the same period. Aquatic insects were collected at densities equal to or greater than the zooplankton during the study, with the family Chironomidae as the dominant aquatic insect taxon collected. Chlorophyta (green algae) was the dominant phytoplankton phylum present during all samples with approximately 97% of the species composition; the genus Cholorella comprised over 95% of all cells in every sample. Other filamentous Chlorophyta genera, like Ulothrix, contributed minor portions of the population. Also, Cyanophyta (blue-greens) and Chrysophyta (golden-brown algae) were found in relatively low numbers. Only limited evidence of zooplankton reproduction was found at the downstream sample site. We concluded that, during the study period, Green River did not exhibit a true plankton community, potamoplankton, but rather a tachyplankton (transient) community. A digital reference collection of zooplankton and phytoplankton was created to provide baseline data for future studies. A long-term plankton data set should be developed if future mussel propagation projects are to be successful in the river

Samuel H. Laughlin letter to Moses Dawson

Letter from Laughlin (Nashville, Tennessee) to Dawson (Cincinnati, Ohio) regarding the presidential race and the national convention.https://www.exhibit.xavier.edu/dawson_correspondence/1096/thumbnail.jp

Complex order parameter symmetry and thermal conductivity

Thermal behaviour of superconductors with complex order parameter symmetry is studied within a weak coupling theory. It is shown numerically, that the thermal nature of the different components of complex order parametrs are qualitatively different. Within the complex order parameter scenario, the recent experimental observations by Krishna {\it et al.}, [Science {\bf 277}, 83 (1997)] on magnetothermal conductivity and by J. Ma {\it et al.}, [Science {\bf 267}, 862 (1995)] on temperature dependent gap anisotropy for high temperature superconductors can have natural explanation.Comment: 6 pages, 3 figures and macros attached, Europhysics Letters (1998) in pres

Fractional Statistics in terms of the r-Generalized Fibonacci Sequences

We develop the basis of the two dimensional generalized quantum statistical systems by using results on $r$-generalized Fibonacci sequences. According to the spin value $s$ of the 2d-quasiparticles, we distinguish four classes of quantum statistical systems indexed by $s=0,1/2:mod(1)$, $s=1/M:mod(1)$, $s=n/M:mod(1)$ and $0\leq s\leq 1:mod(1)$. For quantum gases of quasiparticles with $s=1/M:mod(1)$, $M\geq 2,$, we show that the statistical weights densities $\rho_M$ are given by the integer hierarchies of Fibonacci sequences. This is a remarkable result which envelopes naturally the Fermi and Bose statistics and may be thought of as an alternative way to the Haldane interpolating statistical method.Comment: Late

Branch, Spur, and Feather Formation in Spiral Galaxies

We use hydrodynamical simulations to investigate the response of geometrically thin, self-gravitating, singular isothermal disks of gas to imposed rigidly rotating spiral potentials. By minimizing reflection-induced feedback from boundaries, and by restricting our attention to models where the swing parameter $X \sim 10$, we minimize the swing amplification of global normal modes even in models where Toomre's $Q_g \sim 1-2$ in the gas disk. We perform two classes of simulations: short-term ones over a few galactic revolutions where the background spiral forcing is large, and long-term ones over many galactic revolutions where the spiral forcing is considerably smaller. In both classes of simulations, the initial response of the gas disk is smooth and mimics the driving spiral field. At late times, many of the models evince substructure akin to the so-called branches, spurs, and feathers observed in real spiral galaxies. We comment on the parts played respectively by ultraharmonic resonances, reflection off internal features produced by nonlinear dredging, and local, transient, gravitational instabilites within spiral arms in the generation of such features. Our simulations reinforce the idea that spiral structure in the gaseous component becomes increasingly flocculent and disordered with the passage of time, even when the background population of old disk stars is a grand-design spiral. We speculate that truly chaotic behavior arises when many overlapping ultraharmonic resonances develop in reaction to an imposed spiral forcing that has itself a nonlinear, yet smooth, wave profile.Comment: Accepted for publication in Astrophysical Journal (tentatively October 10, 2003). Version with higher resolution embedded postscript figures at http://astron.berkeley.edu/~sukanya/ms.p

On Measuring Condensate Fraction in Superconductors

An analysis of off-diagonal long-range order in superconductors shows that the spin-spin correlation function is significantly influenced by the order if the order parameter is anisotropic on a microscopic scale. Thus, magnetic neutron scattering can provide a direct measurement of the condensate fraction of a superconductor. It is also argued that recent measurements in high temperature superconductors come very close to achieving this goal.Comment: 4 pages, 1 eps figure, RevTex. A new possibility in the underdoped regime is added. Other corrections are mino

The Effects of Changing Technology: The Impacts of a Changing Cost Structure on Land Tenure Arrangements in the Mississippi Delta, 1996 - 2004

Genetically modified (GM) cotton varieties have changed many aspects of cotton production in the United States. The advent of GM varieties has fueled the ongoing trend of increasing farm size and fewer farmers. Mississippi is no exception to this trend. The rapid adoption of GM cotton varieties in Mississippi has allowed some producers to increase the acreage of their farming operation. This study analyses the impact of GM varieties on relative profitability over certain types of land tenure arrangements. The type of land tenure arrangement and the cost associated with the arrangement are compared to determine relative probabilities of breaking even for different farm sizes in the Mississippi cotton industry.Mississippi cotton production, Genetically Modified cotton varieties, land tenure, structural change, Land Economics/Use,