Settlement Patterns Of Crassostrea virginica (Gmelin, 1791) Larvae In Relation To Tidal Zonation

Experiments were conducted to determine the settlement distribution of the oyster Crassostrea virginica (Gmelin) in relation to tidal zonation in an area where adult populations are largely confined to the intertidal zone. Hatchery-reared pediveliger larvae were interned in PVC tubes positioned at known tidal heights. The influence of non-tidal factors was limited: mesh covering the ends of the tubes prevented loss of larvae to dispersal or predation, the settling substrate was not colonized by competitors, and the effects of light and horizontal currents were minimized. Settlement was found to occur throughout the intertidal zone but predominated at the bottom of the tidal-depth gradient. Few oysters settled in the zone occupied by the adult populations, the intertidal position of which is hypothesized to be controlled by predation

Hard Clam Mercenaria mercenaria

The hard clam is found along the eastern coast of North America from the Gulf of St. Lawrence to Texas. In Chesapeake Bay, the hard clam is restricted to salinities above approximately 12 ppt. An extensive survey of hard clam resources is overdue. Statements concerning long term trends in populations are not feasible. Hard clams ·grow to a maximum shell length of about 120 mm. There are few documented cases of diseases in wild hard clam populations. Parasitic infestations are also slight. The life cycle of the hard clam includes a pelagic larval phase and a relatively sedentary benthic juvenile and adult phase. In Chesapeake Bay, ripe gametes can be found between May and October, and spawning commences when temperatures rise above 20-23 ·c. The larvae are planktotrophic (feeding). Metamorphosis usually commences at a shell length of 200-210 mm. Predation on new recruits is very high; dense aggregations of hard clams have been found in the absence of predators. Aside from predation and fishing pressure, the natural mortality of larger clams appears very low. Hard clams are important suspension-feeding infauna, thus they are important in grazing of primary production, transfer of carbon and nitrogen to benthic food chains, and, through excretion, rapid recycling of particulate nitrogen as ammonia. The major food source for hard clams is planktonic microalgae. In Chesapeake Bay, growth occurs in spring and fall, when optimum water temperatures coincide with abundant food. Clams are capable of living in a variety of sediment types, but higher abundances are found in coarse-grained sediments. Hard clam stocks are susceptible to overfishing. Recruitment rates are poorly understood, as are possible reestablishment periods if areas are depleted through commercial harvesting, and factors influencing larval settlement rates. Hard clam mariculture is well established and could easily be expanded into sites within the Bay. Given the ability of clams to bioaccumulate toxic substances, adequate monitoring should be maintained. The sub lethal effects of toxic material readily found in the lower James River should be examinedhttps://scholarworks.wm.edu/vimsbooks/1018/thumbnail.jp

LABOR PRODUCTIVITY WITHIN THE AFRICAN AGRICULTURAL HOUSEHOLD: THE HOUSEHOLD PRODUCTION MODEL REVISITED

The benchmark concept is used to understand changes in farm household response to development dynamics. 1996-97 cropping seasons data from Cameroon is used to develop and test a "separate spheres" household model. Labor productivity for men and women is discussed, along with their implications for research and resource management policies.agriculture, labor productivity, gender, production, consumption, Consumer/Household Economics, Labor and Human Capital,

Violations of Bjorken scaling in inclusive e+e- annihilation

We discuss the application of renormalization-group techniques to inclusive e+e- annihilation. It is shown by a modest extension of Mueller's techniques that annihilation structure functions have a behavior completely analogous to electroproduction structure functions: Their moments scale for large virtual photon mass, and this scaling is described by "anomalous dimensions" which have a singularity structure and general form very similar to the usual anomalous dimension, though there is no simple relation between the two. We show how information about the structure functions can be deduced from the moments and how, in appropriate limits, deviations from Bjorken scaling can be interpreted in terms of an underlying field theory

Compression of Atomic Phase Space Using an Asymmetric One-Way Barrier

We show how to construct asymmetric optical barriers for atoms. These barriers can be used to compress phase space of a sample by creating a confined region in space where atoms can accumulate with heating at the single photon recoil level. We illustrate our method with a simple two-level model and then show how it can be applied to more realistic multi-level atoms

Problem areas in the use of the firefly luciferase assay for bacterial detection

By purifying the firefly luciferase extract and adding all necessary chemicals but ATP in excess, an assay for ATP was performed by measuring the amount of light produced when a sample containing soluble ATP is added to the luciferase reaction mixture. Instrumentation, applications, and basic characteristics of the luciferase assay are presented. Effect of the growth medium and length of time grown in this medium on ATP per viable E. coli values is shown in graphic form, along with an ATP concentration curve showing relative light units versus ATP injected. Reagent functions and concentration methods are explored. Efforts to develop a fast automatable system to detect the presence of bacteria in biological fluids, especially urine, resulted in the optimization of procedures for use with different types of samples

Framework for Model Independent Analyses of Multiple Extra Quark Scenarios

In this paper we present an analysis strategy and a dedicated tool to determine the exclusion confidence level for any scenario involving multiple heavy extra quarks with generic decay channels, as predicted in several extensions of the Standard Model. We have created, validated and used a software package, called XQCAT (eXtra Quark Combined Analysis Tool), which is based on publicly available experimental data from direct searches for top partners and from Supersymmetry inspired searches. By means of this code, we recast the limits from CMS on new heavy extra quarks considering a complete set of decay channels. The resulting exclusion confidence levels are presented for some simple scenarios with multiple states and general coupling assumptions. Highlighting the importance of combining multiple topology searches to obtain accurate re-interpretations of the existing searches, we discuss the reach of the SUSY analyses so as to set bounds on new quark resonances. In particular, we report on the re-interpretation of the existing limits on benchmark scenarios with one and multiple pair-produced top partners having non-exclusive couplings to the third Standard Model generation of quarks.Comment: 31 pages, 6 figures, 3 tables, version accepted for publication in JHE

External Characteristics of Houses Prone to Woodpecker Damage

Woodpecker (Picidae spp.) damage to houses and buildings is a widespread and locally severe problem, yet the probability and type of damage has never been quantified and related to home characteristics. Woodpeckers excavate holes in homes for a several reasons, mainly for building nest and roost cavities, drumming, and foraging for insects. We examined the external characteristics of houses that were contributing factors in attracting woodpeckers to bore holes in house siding and trim. From March 2001 through April 2002, we surveyed 1,185 houses in the town of Ithaca, Tompkins County, New York. Of the houses visited, 33% had woodpecker problems consisting of either property damage or noise disturbance. The probability of woodpecker-inflicted damage on a house was strongly dependent on siding type. Grooved plywood siding was more likely to be damaged than tongue-and-groove, board-and-batten, clapboard, and nonwood siding types. Probability of damage also increased as the tree density in the yard increased. Interactions occurred between sealant and yard type, and stained houses suffered greater probabilities of woodpecker damage in all wooded yards

Comparison of manual and semi-automated delineation of regions of interest for radioligand PET imaging analysis

BACKGROUND As imaging centers produce higher resolution research scans, the number of man-hours required to process regional data has become a major concern. Comparison of automated vs. manual methodology has not been reported for functional imaging. We explored validation of using automation to delineate regions of interest on positron emission tomography (PET) scans. The purpose of this study was to ascertain improvements in image processing time and reproducibility of a semi-automated brain region extraction (SABRE) method over manual delineation of regions of interest (ROIs). METHODS We compared 2 sets of partial volume corrected serotonin 1a receptor binding potentials (BPs) resulting from manual vs. semi-automated methods. BPs were obtained from subjects meeting consensus criteria for frontotemporal degeneration and from age- and gender-matched healthy controls. Two trained raters provided each set of data to conduct comparisons of inter-rater mean image processing time, rank order of BPs for 9 PET scans, intra- and inter-rater intraclass correlation coefficients (ICC), repeatability coefficients (RC), percentages of the average parameter value (RM%), and effect sizes of either method. RESULTS SABRE saved approximately 3 hours of processing time per PET subject over manual delineation (p 0.8) for both methods. RC and RM% were lower for the manual method across all ROIs, indicating less intra-rater variance across PET subjects' BPs. CONCLUSION SABRE demonstrated significant time savings and no significant difference in reproducibility over manual methods, justifying the use of SABRE in serotonin 1a receptor radioligand PET imaging analysis. This implies that semi-automated ROI delineation is a valid methodology for future PET imaging analysis

Laboratory procedures manual for the firefly luciferase assay for adenosine triphosphate (ATP)

A manual on the procedures and instruments developed for the adenosine triphosphate (ATP) luciferase assay is presented. Data cover, laboratory maintenance, maintenance of bacterial cultures, bacteria measurement, reagents, luciferase procedures, and determination of microbal susceptibility to antibiotics