Diet Composition of Juvenile Pigfish, Orthopristis chrysoptera (Perciformes: Haemulidae), from the Northern Gulf of Mexico

Diets of 954 juvenile pigfish, Orthopristis chrysoptera, collected from 14 1-m3 concrete block artificial reefs approximately 20 km south of Mobile Bay, AL, were examined. A total of 137 specimens (14.4 %) contained food items and were used to perform stomach content analysis. Index of Relative Importance was used to evaluate the contribution of major foods by combining frequency of occurrence, volume, and number. Diets were dominated by shrimps and polychaetes and, to a much lesser extent, sea anemones, fishes, crustaceans, cephalopods, and gammarids. Many stomachs contained various quantities of sand, which indicated a certain amount of bottom feeding by this species. Two distinct dietary preferences based on fish size were revealed

An Evaluation Of Fair Value Accounting For Employee Stock Options

This paper employs static and simulation analysis to consider the measurement properties of the currently active accounting standards for reporting compensation expense related to Employee Stock Options. We find that under a wide range of plausible scenarios the reported expense significantly understates the cash cost incurred by the entity at exercise. The paper includes a discussion of implications for practice and standards setters

Relative Abundance of Postlarval and Juvenile Penaeid Shrimps in Submerged Aquatic Vegetation and Emergent Marsh Habitats

Postlarval and juvenile densities of Farfantepenaeus aztecus, Farfantepenaeus duorarum, and Litopenaeus setiferus were compared among emergent marsh (Spartina alterniflora), submerged aquatic vegetation (Ruppia maritima), and adjacent unvegetated areas at the east end of Fowl River along Mobile Bay, AL. A total of 108 samples were collected between July 1994 and Nov. 1995, of which 76 samples contained at least one of the three penaeid species. Of the 507 penaeid shrimp collected, 303 (60%) were collected in the R. maritima beds, 152 (30%) in the S. alterniflora, and 52 (10%) in the sand/mud habitat. The mean densities of F. aztecus, F. duorarum, and all three penaeid species combined were significantly greater in the R. maritima beds compared with those in both the S. alterniflora and sand/mud habitats. Presence of vegetation appeared to have little effect on shrimp size because no significant difference in size of shrimp between habitats was recorded. Generally, there was little correlation between shrimp density and abiotic factors within the three habitats, but a significant negative correlation was found between F. aztecus density and S. alterniflora density. Results suggest that habitats with submerged aquatic vegetation, R. maritima, are utilized more by both F. aztecus and F. duorarum over those characterized by the emergent vegetation, S. alterniflora. Because shrimp densities did not exhibit any patterns in relation to a variety of hydrographic factors, additional field studies should focus on biotic parameters (i.e., predation, competition, food availability, habitat structure) to better determine the factors that affect penaeid shrimp abundance within estuarine habitats

Economic and Social Impacts of Agriculture-to-Urban Water Transfers: The Arkansas Valley of Colorado

20 pages. Contains 1 page of references

Optimizing Tracking Software for a Time Projection Chamber

International research collaborations will be using accelerators in the U.S. and Europe to produce and detect t5 phase transition in high-density nuclear matter called the Quark-Gluon Plasma, formed in collisions between pairs of A=200 nuclei, for projectiles with kinetic energies large compared to their rest mass energies. Each collaboration will use time projection chambers (TPC) to track thousands ofsecondary charged particles formed in the aftermath ofeach central primary collision. Creating and optimizing TPC tracking software is difficultinsuch a high multiplicity environment, particularly for particles with a low momentum (below 300 MeV/C). A thigh momenta, energy loss is low enough for particle-tracking to use unchanging helix parameters. However, at low momenta, tracking requires changing helix parameters as energy is lost along the path. Tracking software, written for particles of high momenta, may identify the track of a single low momentum particle as two or three separate tracks. This tracking problem was corrected by changing the main tracking algorithm to merge together these two-or-three fragmented, low-momentum particle tracks. Event displays were found exceedingly helpful in diagnosing the problems and optimizing the algorithms

N=1 String Duality

We discuss duality between Type IIA string theory, eleven-dimensional supergravity, and heterotic string theory in four spacetime dimensions with $N=1$ supersymmetry. We find theories whose infrared limit is trivial at enhanced symmetry points as well as theories with $N=1$ supersymmetry but the field content of $N=4$ theories which flow to the $N=4$ fixed line in the infrared.Comment: 14 pages, harvma

Scattering of Macroscopic Heterotic Strings

We show that macroscopic heterotic strings, formulated as strings which wind around a compact direction of finite but macroscopic extent, exhibit non-trivial scattering at low energies. This occurs at order velocity squared and may thus be described as geodesic motion on a moduli space with a non-trivial metric which we construct. Our result is in agreement with a direct calculation of the string scattering amplitude.Comment: 14 pp (harvmac l

The integral monodromy of hyperelliptic and trielliptic curves

We compute the \integ/\ell and \integ_\ell monodromy of every irreducible component of the moduli spaces of hyperelliptic and trielliptic curves. In particular, we provide a proof that the \integ/\ell monodromy of the moduli space of hyperelliptic curves of genus $g$ is the symplectic group \sp_{2g}(\integ/\ell). We prove that the \integ/\ell monodromy of the moduli space of trielliptic curves with signature $(r,s)$ is the special unitary group \su_{(r,s)}(\integ/\ell\tensor\integ[\zeta_3])