1,517 research outputs found

    Introduction of Computer Aided Instruction into an Aerospace Engineering Curriculum

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    The computer-aided education program at the U. S. Naval Academy has developed over a two-year period a nucleus of well trained and experienced faculty and technical staff members. The overall approach being used to introduce the use of computeraided instruction into the academic program is described. Details of the participation of the Aerospace Engineering faculty in this program, and the work done to date in courses which support the Aerospace Engineering curriculum, are presented

    How does iron interact with sporopollenin exine capsules? An X-ray absorption study including microfocus XANES and XRF imaging

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    Sporopollenin exine capsules (SECs) derived from plant spores and pollen grains have been proposed as adsorption, remediation and drug delivery agents. Despite many studies there is scant structural data available. This X-ray absorption investigation represents the first direct structural data on the interaction of metals with SECs and allows elucidation of their structure–property relationships. Fe K-edge XANES and EXAFS data have shown that the iron local environment in SECs (derived from Lycopodium clavatum) reacted with aqueous ferric chloride solutions is similar to that of ferrihydrite (FeOOH) and by implication ferritin. Fe Kα XRF micro-focus experiments show that there is a poor correlation between the iron distribution and the underlying SEC structure indicating that the SEC is coated in the FeOOH material. In contrast, the Fe Kα XRF micro-focus experiments on SECs reacted with aqueous ferrous chloride solutions show that there is a very high correlation between the iron distribution and the SEC structure, indicating a much more specific form of interaction of the iron with the SEC surface functional groups. Fe K-edge XANES and EXAFS data show that the FeII can be easily oxidised to give a structure similar to, but not identical to that in the FeIII case, and that even if anaerobic conditions are used there is still partial oxidation to FeIII

    Therapy of pancreatic cancer via an EphA2 receptor-targeted delivery of gemcitabine.

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    First line treatment for pancreatic cancer consists of surgical resection, if possible, and a subsequent course of chemotherapy using the nucleoside analogue gemcitabine. In some patients, an active transport mechanism allows gemcitabine to enter efficiently into the tumor cells, resulting in a significant clinical benefit. However, in most patients, low expression of gemcitabine transporters limits the efficacy of the drug to marginal levels, and patients need frequent administration of the drug at high doses, significantly increasing systemic drug toxicity. In this article we focus on a novel targeted delivery approach for gemcitabine consisting of conjugating the drug with an EphA2 targeting agent. We show that the EphA2 receptor is highly expressed in pancreatic cancers, and accordingly, the drug-conjugate is more effective than gemcitabine alone in targeting pancreatic tumors. Our preliminary observations suggest that this approach may provide a general benefit to pancreatic cancer patients and offers a comprehensive strategy for enhancing delivery of diverse therapeutic agents to a wide range of cancers overexpressing EphA2, thereby potentially reducing toxicity while enhancing therapeutic efficacy

    Population Genetic Structure of Gray Wolves (Canis lupus) in a Marine Archipelago Suggests Island-Mainland Differentiation Consistent with Dietary Niche

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    Background: Emerging evidence suggests that ecological heterogeneity across space can influence the genetic structure of populations, including that of long-distance dispersers such as large carnivores. On the central coast of British Columbia, Canada, wolf (Canis lupus L., 1758) dietary niche and parasite prevalence data indicate strong ecological divergence between marine-oriented wolves inhabiting islands and individuals on the coastal mainland that interact primarily with terrestrial prey. Local holders of traditional ecological knowledge, who distinguish between mainland and island wolf forms, also informed our hypothesis that genetic differentiation might occur between wolves from these adjacent environments. Results: We used microsatellite genetic markers to examine data obtained from wolf faecal samples. Our results from 116 individuals suggest the presence of a genetic cline between mainland and island wolves. This pattern occurs despite field observations that individuals easily traverse the 30 km wide study area and swim up to 13 km among landmasses in the region. Conclusions: Natal habitat-biased dispersal (i.e., the preference for dispersal into familiar ecological environments) might contribute to genetic differentiation. Accordingly, this working hypothesis presents an exciting avenue for future research where marine resources or other components of ecological heterogeneity are present

    Presence of Juvenile Blackfin Snapper, Lutjanus buccanella, and Snowy Grouper, Epinephelus niveatus, on Shallow-water Artificial Reefs

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    The inshore environment of Broward County, Florida consists of three reef tracts, each separated by sand substrate, running parallel to the coastline in sequentially deeper water. A wide variety of artificial reef designs have been deployed in Broward County, many lying in sand flats between the reeftracts. From 1995 through 2002, over 1,100 visual fish censuses (predominantly point-counts) were completed on the three natural reeftracts in water depths from 3 m to 30 m and over 1,100 censuses were done on artificial reefs at depths of 7 m to 23 m. Curiously, the juvenile stages of two deeper-water species of the snapper/grouper complex, the blackfin snapper (Lutjanus buccanella) and the snowy grouper (Epinephelus niveatus), appear to prefer artificial reefs located in the sand flat separating the second and third reeftracts to nearby natural reef areas. Five hundred and forty blackfin snapper have been recorded in 64 visual censuses and nine snowy grouper have been observed in seven counts on artificial reefs. Despite the large volume of visual census data collected thus far, these two species have never been recorded on nearby natural reef tracts. The reasons for this unanticipated observation is unclear but it provides an excellent launch-point for an examination of juvenile habitat requirements, natural availability of these requirements, and the potential for artificial substrate to be used in managing these species

    Doppler ultrasound color flow imaging in the study of breast cancer: Preliminary findings

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    A prospective study of the Doppler color flow features of 55 proved breast cancers was performed. On a three-level scale of low to marked vascularity, visual assessment of the color flow images classified 82% of the cancers as moderately or markedly vascular (minimal: 14%, moderate: 29%, marked: 53%). Four percent of the cancers had no detectable flow. In 29 women, a volume of tissue comparable to the cancer was scanned in the contralateral normal breast. Sixty-nine percent of the normal breasts had moderate or marked vascularity (minimal: 28%, moderate: 41%, marked: 28%), and 3% were avascular. There was poor distinction between normal tissues and cancer which suggests that more sensitive Doppler methods than were employed in this study may be needed in order to detect the small vessel flow reported to be rather specific for malignancy. The high, 82%, detection rate of tumor vessels in this study suggests the potential use of color flow Doppler for directing more specific but lengthy Doppler procedures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28897/1/0000734.pd

    The optical calcium frequency standards of PTB and NIST

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    We describe the current status of the Ca optical frequency standards with laser-cooled neutral atoms realized in two different laboratories for the purpose of developing a possible future optical atomic clock. Frequency measurements performed at the Physikalisch-Technische Bundesanstalt (PTB) and the National Institute of Standards and Technology (NIST) make the frequency of the clock transition of 40Ca one of the best known optical frequencies (relative uncertainty 1.2e-14) and the measurements of this frequency in both laboratories agree to well within their respective uncertainties. Prospects for improvement by orders of magnitude in the relative uncertainty of the standard look feasible.Comment: 13 pages, 11 figures, to appear in Comptes Rendus Physiqu

    The Upper Respiratory Tract as a Microbial Source for Pulmonary Infections in Cystic Fibrosis. Parallels from Island Biogeography

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    A continuously mixed series of microbial communities inhabits various points of the respiratory tract, with community composition determined by distance from colonization sources, colonization rates, and extinction rates. Ecology and evolution theory developed in the context of biogeography is relevant to clinical microbiology and could reframe the interpretation of recent studies comparing communities from lung explant samples, sputum samples, and oropharyngeal swabs. We propose an island biogeography model of the microbial communities inhabiting different niches in human airways. Island biogeography as applied to communities separated by time and space is a useful parallel for exploring microbial colonization of healthy and diseased lungs, with the potential to inform our understanding of microbial community dynamics and the relevance of microbes detected in different sample types. In this perspective, we focus on the intermixed microbial communities inhabiting different regions of the airways of patients with cystic fibrosis
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