Ecological patterns during ontogeny in the bicolor damselfish, Stegastes partitus, Poey

This dissertation examined the ecological constraints during the early life history of the bicolor damselfish, Stegastes partitus Poey (Perciformes, Pomacentridae). A series of studies, conducted in Teague Bay, St. Croix and Discovery Bay, Jamaica between 1991 and 1996, determined the cause of variation in length of the planktonic larval period, the effect of larval history on settlement success and examined the causes behind the patterns of distribution and population structure seen throughout its geographic range. Variable growth rates in early-stage larvae established a canalized trajectory toward larval competence and provides a mechanism for determining planktonic duration. Using otolith microstructure I determined that larvae with the fastest growth rates during the first 10 days post-hatching had planktonic durations up to 15 days shorter than larvae with the slowest growth rates. Moreover, there was a positive correlation between pre- and post-settlement growth. With a series of experiments, I determined that larval settlement behavior of S. partitus was most important in determining small-scale (10\u27s of meters) distribution patterns and that differential survival after settlement enhanced these initial patterns. Survival was related to the structural architecture of different substrates which determined refuge suitability and predation risk. During ontogeny, juvenile bicolor damselfish can increase their overall fitness by selecting small rubble substrates at settlement then switching to adult substrates at maturity. Juveniles selecting this strategy had a 50% increase in survivorship over larvae which settled directly to the adult coral substrate. I interpret these results with a graphical model and discuss its relevance to identifying trade-offs and predicting habitat shifts during ontogeny. At larger spatial scales (100\u27s of meters) larval recruitment was of minor importance in structuring adult populations in St. Croix. The additive effects of interspecific competition, food supply, and the physical and biological features of various reef habitats significantly affected juvenile growth. A prolonged juvenile period, due to reduced growth, indirectly affected mortality and thus adult abundance. These effects were nearly identical on St. Croix and Jamaican barrier reefs and were altered only by site-specific predation intensity. The relative importance of these various ecological constraints on life history patterns is discussed

Surveillance for West Nile Virus in Clinic-admitted Raptors, Colorado

In 2005, 13.5% of clinic-admitted raptors in northern Colorado tested positive for West Nile virus (WNV). Clinic-admitted–raptor surveillance detected WNV activity nearly 14 weeks earlier than other surveillance systems. WNV surveillance using live raptor admissions to rehabilitation clinics may offer a novel surveillance method and should be considered along with other techniques already in use

Nonlinear Analysis of the Space Shuttle Superlightweight LO2 Tank

Results of linear bifurcation and nonlinear analyses of the Space Shuttle superlightweight (SLWT) external liquid-oxygen (LO2) tank for an important early booster ascent loading condition are presented. These results for thin-walled linear elastic shells that are subjected to combined mechanical and thermal loads illustrate an important type of response mode that may be encountered in the design of other liquid-fuel launch vehicles. Linear bifurcation analyses are presented that predict several nearly equal eigenvalues that correspond to local buckling modes in the forward ogive section of the LO2 tank. In contrast, the nonlinear response phenomenon is shown to consist of short-wavelength bending deformations in the forward ogive and barrel sections of the LO2 tank that growing amplitude in a stable manner increasing load. Imperfection sensitivity analyses are presented that show that the presence of several nearly equal eigenvalues does not lead to a premature general instability mode for the forward ogive section. For the linear bifurcation and nonlinear analyses, the results show that accurate predictions of the response of the shield generally require a large-scale, high-fidelity finite-element model. Results are also presented that show that the SLWT LO2 tank can support loads in excess of approximately 2.6 times the values of the operational loads considered

A multi-layer `gas of circles' Markov random field model for the extraction of overlapping near-circular objects

We propose a multi-layer binary Markov random field (MRF) model that assigns high probability to object configurations in the image domain consisting of an unknown number of possibly touching or overlapping near-circular objects of approximately a given size. Each layer has an associated binary field that specifies a region corresponding to objects. Overlapping objects are represented by regions in different layers. Within each layer, long-range interactions favor connected components of approximately circular shape, while regions in different layers that overlap are penalized. Used as a prior coupled with a suitable data likelihood, the model can be used for object extraction from images, e.g. cells in biological images or densely-packed tree crowns in remote sensing images. We present a theoretical and experimental analysis of the model, and demonstrate its performance on various synthetic and biomedical images

Identification of an iron–hepcidin complex

Following its identification as a liver-expressed antimicrobial peptide, the hepcidin peptide was later shown to be a key player in iron homoeostasis. It is now proposed to be the 'iron hormone' which, by interacting with the iron transporter ferroportin, prevents further iron import into the circulatory system. This conclusion was reached using the corresponding synthetic peptide, emphasizing the functional importance of the mature 25-mer peptide, but omitting the possible functionality of its maturation. From urine-purified native hepcidin, we recently demonstrated that a proportion of the purified hepcidin had formed iron-hepcidin complexes. This interaction was investigated further by computer modelling and, based on the sequence similarity of hepcidin with metallothionein, a three-dimensional model of hepcidin, containing one atom of iron, was constructed. To characterize these complexes further, the interaction with iron was analysed using different spectroscopic methods. Monoferric hepcidin was identified by MS, as were possibly other complexes containing two and three atoms of iron respectively, although these were present only in minor amounts. UV/visible absorbance and CD studies identified the iron-binding events which were facilitated at a physiological pH. EPR spectroscopy identified the ferric state of the bound metal, and indicated that the iron-hepcidin complex shares some similarities with the rubredoxin iron-sulfur complex, suggesting the presence of Fe(3+) in a tetrahedral sulfur co-ordination. The potential roles of iron binding for hepcidin are discussed, and we propose either a regulatory function in the maturation of pro-hepcidin into active hepcidin or as the necessary link in the interaction between hepcidin and ferroportin

Incorporating Personalization Features in a Hospital-Stay Summary Generation System

Most of the currently available health resources contain vast amount of information that are created by keeping the “general” population in mind, which in reality, might not be useful for anyone. One approach to providing comprehensible health information to patients is to generate summaries that are personalized to each individual. This paper details the design of a personalized hospital-stay summary generation system that tailors its content to the patient’s understanding of medical terminologies and their level of engagement in improving their own health. Our summaries were found to cover around 80% of the health concepts that were considered as important by a doctor or a nurse. An online survey conducted on 150 participants verified that our algorithm’s interpretation of the personalization parameters is representative of that of a larger population

MicroRNA and metabolomics signatures for adrenomyeloneuropathy disease severity

Adrenomyeloneuropathy (AMN), the slow progressive phenotype of adrenoleukodystrophy (ALD), has no clinical plasma biomarker for disease progression. This feasibility study aimed to determine whether metabolomics and micro-RNA in blood plasma provide a potential source of biomarkers for AMN disease severity. Metabolomics and RNA-seq were performed on AMN and healthy human blood plasma. Biomarker discovery and pathway analyses were performed using clustering, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and regression against patient\u27s clinical Expanded Disability Status Score (EDSS). Fourteen AMN and six healthy control samples were analyzed. AMN showed strong disease-severity-specific metabolic and miRNA clustering signatures. Strong, significant clinical correlations were shown for 7-alpha-hydroxy-3-oxo-4-cholestenoate (7-HOCA) (r (2) = 0.83, p \u3c 0.00001), dehydroepiandrosterone sulfate (DHEA-S; r (2) = 0.82, p \u3c 0.00001), hypoxanthine (r (2) = 0.82, p \u3c 0.00001), as well as miRNA-432-5p (r (2) = 0.68, p \u3c 0.00001). KEGG pathway comparison of mild versus severe disease identified affected downstream systems: GAREM, IGF-1, CALCRL, SMAD2&3, glutathione peroxidase, LDH, and NOS. This feasibility study demonstrates that miRNA and metabolomics are a source of potential plasma biomarkers for disease severity in AMN, providing both a disease signature and individual markers with strong clinical correlations. Network analyses of affected systems implicate differentially altered vascular, inflammatory, and oxidative stress pathways, suggesting disease-severity-specific mechanisms as a function of disease severity

Comparative Use of a Caribbean Mesophotic Coral Ecosystem and Association with Fish Spawning Aggregations by Three Species of Shark

Understanding of species interactions within mesophotic coral ecosystems (MCEs; ~ 30–150 m) lags well behind that for shallow coral reefs. MCEs are often sites of fish spawning aggregations (FSAs) for a variety of species, including many groupers. Such reproductive fish aggregations represent temporal concentrations of potential prey that may be drivers of habitat use by predatory species, including sharks. We investigated movements of three species of sharks within a MCE and in relation to FSAs located on the shelf edge south of St. Thomas, United States Virgin Islands. Movements of 17 tiger (Galeocerdo cuvier), seven lemon (Negaprion brevirostris), and six Caribbean reef (Carcharhinus perezi) sharks tagged with acoustic transmitters were monitored within the MCE using an array of acoustic receivers spanning an area of 1,060 km2 over a five year period. Receivers were concentrated around prominent grouper FSAs to monitor movements of sharks in relation to these temporally transient aggregations. Over 130,000 detections of telemetered sharks were recorded, with four sharks tracked in excess of 3 years. All three shark species were present within the MCE over long periods of time and detected frequently at FSAs, but patterns of MCE use and orientation towards FSAs varied both spatially and temporally among species. Lemon sharks moved over a large expanse of the MCE, but concentrated their activities around FSAs during grouper spawning and were present within the MCE significantly more during grouper spawning season. Caribbean reef sharks were present within a restricted portion of the MCE for prolonged periods of time, but were also absent for long periods. Tiger sharks were detected throughout the extent of the acoustic array, with the MCE representing only portion of their habitat use, although a high degree of individual variation was observed. Our findings indicate that although patterns of use varied, all three species of sharks repeatedly utilized the MCE and as upper trophic level predators they are likely involved in a range of interactions with other members of MCEs