Biogeochemical Dynamics of Dissolved Si in Taylor Valley, Antarctica

This thesis is part of the McMurdo Dry Valleys (MCM) Long-Tern Ecological Research (LTER) study in Southern Victoria Land, Antarctica. With the exception of the ice-covered lakes, there is little liquid water present in the valleys for most of the year. Chemical weathering is thought to occur more readily in warm and wet climates, however recent research has shown that it can occur in cold and dry environments. The chemical weathering of rocks and sediments in Taylor Valley occurs in the stream channels when liquid water is present, resulting from the melting of glacial ice during the austral summer. Not only is silicon an important element geologically, it is an important biogeochemical element, as aquatic microorganisms, such as diatoms, need it for growth. Silica (Si) is thought to be one of the chemicals that is dissolved by the glacier meltwater as it flows into the lakes. This thesis is an aqueous geochemical study of the Si found in the streams and lakes. Water samples were collected at the beginning of the austral summer and then again in midsummer from Lakes Bonney, Fryxell and Hoare in the Taylor Valley for the past 3 field seasons. Stream samples from each of the lake basins were also collected during the summer months. To analyze the concentrations of reactive Si in the water samples, a colorimetric method was used. Streams of the Lake Fryxell basin had the highest average Si concentrations, - 1.5 mgL. Streams that flow into Lake Hoare had the lowest average concentrations, -0.2 mgL. This difference is most likely a result of the length of the streams. The streams in Lake Fryxell basin are longer that those of the Lake Hoare, and therefore the water is in contact with the underlying sediment for a longer period of time, resulting in more Si being dissolved. The annual flux of Si into the lakes was determined by calculating the average Si concentrations in the streams and multiplying by the volume of stream flow for each lake basin. The highest Si fluxes occurred in the Lake Bonney basin followed by Lake Fryxell and Lake Hoare. When these fluxes are normalized to lake area, the values range from 212 mgsi/m2yr in Lake Bonney, 29 mgsi/m2yr in Lake Fryxell and 12 mgSi/m2yr in Lake Hoare. Si concentrations in the lakes vary over time due to physical, chemical and biological processes. The concentrations in the lakes could be influenced by dilution with stream water of lower Si concentrations, precipitation and dissolution of Si within the water column, or biological uptake of Si by diatoms. For example, a decrease in Si concentration occurred in the upper part of the water column of Lake Hoare between the early and midsummer sample collections in all three seasons. The change in Si is much greater than expected from uptake by diatoms. Approximately 0.03% of the Si decrease can be attributed to biological uptake, based on primary productivity measurements. Therefore, other physical processes must control the Si variations in Lake Hoare.National Science Foundation Office of Polar Programs OPP 9810219 and OPP 009625

Use of the Hedonic Method to Estimate Lake Sedimentation Impacts on Property Values in Mountain Park and Roswell, GA

Metropolitan Atlanta has experienced explosive population growth in the past few decades, which has resulted in rapid residential growth. The City of Roswell is one the best examples of residential growth on the urban fringe of Atlanta, with its housing stock increasing by more than 50 percent from 1990 to 2000. Stormwater runoff created from these development sites is expected to be causing sedimentation accumulation in lakes within Roswell and a neighboring, downstream wildlife refuge located in the City of Mountain Park. Because sedimentation tends to fill-in and shrink lakes, our results provide some indication of the potential property damages associated with sedimentation. Furthermore, our results provide evidence that lake value is not monotonically increasing with lake size, which is believed to be due to the influence that geographic, environmental, and social factors have on the degree to which lakes add value to housing prices.Land Economics/Use,

A Noninvasive Method For In situ Determination of Mating Success in Female American Lobsters (Homarus americanus)

Despite being one of the most productive fisheries in the Northwest Atlantic, much remains unknown about the natural reproductive dynamics of American lobsters. Recent work in exploited crustacean populations (crabs and lobsters) suggests that there are circumstances where mature females are unable to achieve their full reproductive potential due to sperm limitation. To examine this possibility in different regions of the American lobster fishery, a reliable and noninvasive method was developed for sampling large numbers of female lobsters at sea. This method involves inserting a blunt-tipped needle into the female\u27s seminal receptacle to determine the presence or absence of a sperm plug and to withdraw a sample that can be examined for the presence of sperm. A series of control studies were conducted at the dock and in the laboratory to test the reliability of this technique. These efforts entailed sampling 294 female lobsters to confirm that the presence of a sperm plug was a reliable indicator of sperm within the receptacle and thus, mating. This paper details the methodology and the results obtained from a subset of the total females sampled. Of the 230 female lobsters sampled from George\u27s Bank and Cape Ann, MA (size range = 71-145 mm in carapace length), 90.3% were positive for sperm. Potential explanations for the absence of sperm in some females include: immaturity (lack of physiological maturity), breakdown of the sperm plug after being used to fertilize a clutch of eggs, and lack of mating activity. The surveys indicate that this technique for examining the mating success of female lobsters is a reliable proxy that can be used in the field to document reproductive activity in natural populations

A Noninvasive Method For In situ Determination of Mating Success in Female American Lobsters (Homarus americanus)

Despite being one of the most productive fisheries in the Northwest Atlantic, much remains unknown about the natural reproductive dynamics of American lobsters. Recent work in exploited crustacean populations (crabs and lobsters) suggests that there are circumstances where mature females are unable to achieve their full reproductive potential due to sperm limitation. To examine this possibility in different regions of the American lobster fishery, a reliable and noninvasive method was developed for sampling large numbers of female lobsters at sea. This method involves inserting a blunt-tipped needle into the female\u27s seminal receptacle to determine the presence or absence of a sperm plug and to withdraw a sample that can be examined for the presence of sperm. A series of control studies were conducted at the dock and in the laboratory to test the reliability of this technique. These efforts entailed sampling 294 female lobsters to confirm that the presence of a sperm plug was a reliable indicator of sperm within the receptacle and thus, mating. This paper details the methodology and the results obtained from a subset of the total females sampled. Of the 230 female lobsters sampled from George\u27s Bank and Cape Ann, MA (size range = 71-145 mm in carapace length), 90.3% were positive for sperm. Potential explanations for the absence of sperm in some females include: immaturity (lack of physiological maturity), breakdown of the sperm plug after being used to fertilize a clutch of eggs, and lack of mating activity. The surveys indicate that this technique for examining the mating success of female lobsters is a reliable proxy that can be used in the field to document reproductive activity in natural populations

Quality of care for NSAID users: development of an assessment tool

Objective. Assessments of NSAID use based on authoritative guidelines typically overlook patients’ views and nuances of \ud medical history. Our objective was to develop an assessment tool that incorporates these aspects, and technical items, for quality of care assessments in NSAID users. \ud \ud Methods. Patients newly referred to a university hospital were interviewed by a nurse using an agreed template. A multidisciplinary group of rheumatologists, nurse specialists, primary care physicians and a pharmacist reviewed current guidance and systematic reviews on NSAID use, and a series of interview transcripts. The group agreed, by informal consensus, important determinants of effective and safe NSAID use. Technical aspects of medical care and items that reflected interpersonal care were included in an index for assessing quality of care for individual patients. Interview transcripts of 100 patients were scored by panel members and reliability of scores was tested by calculating weighted percentage agreement and the kappa statistic. \ud \ud Results. Our final index had five domains: medical risk factors; steps taken to reduce risk; knowledge of adverse effects; NSAID dose; and cost efficiency. Each item was scored 0, 1 or 2. Scores were summed, giving a maximum of 10 (low scores indicating low quality). Intra-rater agreement was >90%; kappa was 0.47–0.87 for individual domains and 0.59 for overall score. Inter-rater agreement for overall score was 95%; kappa was 0.25–0.78 for domains and 0.48 for overall score. Patients with especially low scores were identified using the mode of scores for five assessors; obvious clinical concerns were identified, supporting index face validity. \ud \ud Conclusions. A simple index to evaluate quality of care for NSAID users based on a patient interview is described. This may be used by one or more assessors to examine care standards and highlight deficiencies in relation to NSAID use in practice

A noninvasive method for in situ determination of mating success in female American lobsters (Homarus americanus)

Despite being one of the most productive fisheries in the Northwest Atlantic, much remains unknown about the natural reproductive dynamics of American lobsters. Recent work in exploited crustacean populations (crabs and lobsters) suggests that there are circumstances where mature females are unable to achieve their full reproductive potential due to sperm limitation. To examine this possibility in different regions of the American lobster fishery, a reliable and noninvasive method was developed for sampling large numbers of female lobsters at sea. This method involves inserting a blunt-tipped needle into the female's seminal receptacle to determine the presence or absence of a sperm plug and to withdraw a sample that can be examined for the presence of sperm. A series of control studies were conducted at the dock and in the laboratory to test the reliability of this technique. These efforts entailed sampling 294 female lobsters to confirm that the presence of a sperm plug was a reliable indicator of sperm within the receptacle and thus, mating. This paper details the methodology and the results obtained from a subset of the total females sampled. Of the 230 female lobsters sampled from George's Bank and Cape Ann, MA (size range = 71-145 mm in carapace length), 90.3% were positive for sperm. Potential explanations for the absence of sperm in some females include: immaturity (lack of physiological maturity), breakdown of the sperm plug after being used to fertilize a clutch of eggs, and lack of mating activity. The surveys indicate that this technique for examining the mating success of female lobsters is a reliable proxy that can be used in the field to document reproductive activity in natural populations

The petrography of the Lower Purbeck Limestones of Dorset

The petrography of the limestone types found in the Lower Purbeck of Dorset is described. Four main types are distinguished namely algal limestones, pellet-limestones, shell-limestones; and replacement-limestones produced by the replacement of gypsum and anhydrite by calcite. The distribution of these limestones especially as revealed by coastal sections, is tabulated. From these studies it is deducted that the principal environment of deposition was a lagoon, the seaward margin of which was restricted by an algal barrier. On the landward side of this barrier evaporites, pellet-limestones and shell limestones were deposited in a lateral sequence. There is evidence to suggest the occurrence of lower salinities to the west than to the east. This lateral change in salinity is probably due to dilution by river water in the west, especially during Hard Cap times. The origin of two post depositional breccias is also discussed.<p

The Gate

This project is a short novelette told from the points of view of several different characters. The story is set in an airport and follows these characters as they wait for their flight to arrive. Each of the characters is observing the others, much like people do everyday without realizing it. Their personalities and histories are built throughout the story through their thought processes and the memories they have that are triggered by the observations they make, thus removing the reader from the airport setting occasionally to scenes that take place throughout the characters’ lives. This story is intended to allow any reader to relate with one or more of the characters. Some themes that are presented throughout the story are that of observation and the process of relationships

Application of sex-specific single-nucleotide polymorphism filters in genome-wide association data

We explored five sex-specific quality control filters in North American Rheumatoid Arthritis Consortium's Illumina 550 k datasets. Three X chromosome and three autosomal single-nucleotide polymorphisms flagged by sex quality control filters were missed by filters of call rate at 95% and Hardy-Weinberg equilibrium at 10-6. We applied a subset of these sex-specific quality control filters to eight chromosomes in the Framingham Heart Study samples genotyped by Affymetrix 500 k SNP arrays, and identified another two single-nucleotide polymorphisms that failed to be picked up by the above global filters