1,766 research outputs found

    Microbiological analysis of debris from STS-42 IML-1 by direct plating of rinse waters

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    Microbial analysis of air filter debris from the Spacelab International Microgravity Laboratory-1 (IML-1) mission was performed via direct plating of rinse waters on a battery of selective and nonselective nutrient agars. Microbial isolates were identified using Minitek and Biolog technologies. Twenty-four types of bacteria were recovered and classified; a similar number of fungal types was observed, but these were not identified. This procedure can provide information about the proportions of organism types present at the time of debris collection

    Development of static system procedures to study aquatic biofilms and their responses to disinfection and invading species

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    The microbial ecology facility in the Analytical and Physical Chemistry Branch at Marshall Space Flight Center is tasked with anticipation of potential microbial problems (and opportunities to exploit microorganisms) which may occur in partially closed systems such as space station/vehicles habitats and in water reclamation systems therein, with particular emphasis on the degradation of materials. Within this context, procedures for microbial biofilm research are being developed. Reported here is the development of static system procedures to study aquatic biofilms and their responses to disinfection and invading species. Preliminary investigations have been completed. As procedures are refined, it will be possible to focus more closely on the elucidation of biofilm phenomena

    Some Aspects of Regeneration Silviculture in Spruce-Aspen Stands in Alberta

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    Trust in Academia: How Chief Academic Officers Build and Maintain Faculty Trust

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    As the role of academic leadership has grown more complex, particularly as leaders are increasingly tasked with leading educational innovation initiatives, building faculty trust has become an essential task for chief academic officers (CAOs). Due to the general lack of research into this role, though, little is known about how they understand and approach building faculty trust. The purpose of this qualitative, single, holistic case study was to understand how executive academic administrators at private colleges approach building and maintaining trust with their faculty in general and also through educational innovation and what specific challenges they have identified in these efforts. By using a social constructionist paradigm, semistructured 90-minute interviews were conducted with a semipurposive sample of six CAOs selected from within the Commission on Independent Colleges and Universities in New York. The respondents answered open-ended questions concerning how they define trust in leaders, what specific actions they have taken to build trust among their faculty, and what challenges they have faced in trust-building. They were then asked these same questions but specifically within the context of educational innovation initiatives they have overseen. The interviews were transcribed and coded in three passes, first using predetermined codes related to trust and innovation, then using process coding, and a final pass using values coding. The findings indicated that respondents recognized that trust was essential for effective faculty leadership and that while trust was not often built intentionally, they sought to build it through open and honest communication, by preserving institutional mission, and by understanding the role of the faculty. Additionally, the respondents indicated that innovation is different in top-down versus bottom-up initiatives, that identifying faculty to lead innovation and leading alongside them builds trust, as does incentivizing innovation. Based on these findings, it is recommended that CAOs should work to build trust more intentionally, that communication skills should factor heavily into the selection and ongoing training of CAOs, along with training CAOs in the preservation of institutional mission, that innovation should be incentivized by institutions, and that faculty leadership programs should be established to build innovative leaders that the CAO works alongside

    Growth of Alberta White Spruce After Release from Aspen Competition

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    Transitions in coral reef accretion rates linked to intrinsic ecological shifts on turbid-zone nearshore reefs

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    Nearshore coral communities within turbid settings are typically perceived to have limited reef-building capacity. However, several recent studies have reported reef growth over millennial time scales within such environments and have hypothesized that depth-variable community assemblages may act as equally important controls on reef growth as they do in clear-water settings. Here, we explicitly test this idea using a newly compiled chronostratigraphic record (31 cores, 142 radiometric dates) from seven proximal (but discrete) nearshore coral reefs located along the central Great Barrier Reef (Australia). Uniquely, these reefs span distinct stages of geomorphological maturity, as reflected in their elevations below sea level. Integrated age-depth and ecological data sets indicate that contemporary coral assemblage shifts, associated with changing light availability and wave exposure as reefs shallowed, coincided with transitions in accretion rates at equivalent core depths. Reef initiation followed a regional ∼1 m drop in sea level (1200–800 calibrated yr B.P.) which would have lowered the photic floor and exposed new substrate for coral recruitment by winnowing away fine seafloor sediments. We propose that a two-way feedback mechanism exists where past growth history influences current reef morphology and ecology, ultimately driving future reef accumulation and morphological change. These findings provide the first empirical evidence that nearshore reef growth trajectories are intrinsically driven by changes in coral community structure as reefs move toward sea level, a finding of direct significance for predicting the impacts of extrinsically driven ecological change (e.g., coral-algal phase shifts) on reef growth potential within the wider coastal zone on the Great Barrier Reef

    Decomposition of thin titanium deuteride films: thermal desorption kinetics studies combined with microstructure analysis

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    The thermal evolution of deuterium from thin titanium films, prepared under UHV conditions and deuterated in situ at room temperature, has been studied by means of thermal desorption mass spectrometry (TDMS) and a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The observed Ti film thickness dependent morphology was found to play a crucial role in the titanium deuteride (TiDy) film formation and its decomposition at elevated temperatures. TDMS heating induced decomposition of fine-grained thin Ti films, of 10–20 nm thickness, proceeds at low temperature (maximum peak temperature Tm about 500 K) and its kinetics is dominated by a low energy desorption (ED = 0.61 eV) of deuterium from surface and subsurface areas of the Ti film. The origin of this process is discussed as an intermediate decomposition state towards recombinative desorption of molecular deuterium. The TiDy bulk phase decomposition becomes dominant in the kinetics of deuterium evolution from thicker TiDy films. The dominant TDMS peak at approx. Tm = 670 K, attributed to this process, is characterized by ED = 1.49 eV

    Protein kinase C-dependent signaling controls the midgut epithelial barrier to malaria parasite infection in anopheline mosquitoes.

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    Anopheline mosquitoes are the primary vectors of parasites in the genus Plasmodium, the causative agents of malaria. Malaria parasites undergo a series of complex transformations upon ingestion by the mosquito host. During this process, the physical barrier of the midgut epithelium, along with innate immune defenses, functionally restrict parasite development. Although these defenses have been studied for some time, the regulatory factors that control them are poorly understood. The protein kinase C (PKC) gene family consists of serine/threonine kinases that serve as central signaling molecules and regulators of a broad spectrum of cellular processes including epithelial barrier function and immunity. Indeed, PKCs are highly conserved, ranging from 7 isoforms in Drosophila to 16 isoforms in mammals, yet none have been identified in mosquitoes. Despite conservation of the PKC gene family and their potential as targets for transmission-blocking strategies for malaria, no direct connections between PKCs, the mosquito immune response or epithelial barrier integrity are known. Here, we identify and characterize six PKC gene family members--PKCδ, PKCε, PKCζ, PKD, PKN, and an indeterminate conventional PKC--in Anopheles gambiae and Anopheles stephensi. Sequence and phylogenetic analyses of the anopheline PKCs support most subfamily assignments. All six PKCs are expressed in the midgut epithelia of A. gambiae and A. stephensi post-blood feeding, indicating availability for signaling in a tissue that is critical for malaria parasite development. Although inhibition of PKC enzymatic activity decreased NF-κB-regulated anti-microbial peptide expression in mosquito cells in vitro, PKC inhibition had no effect on expression of a panel of immune genes in the midgut epithelium in vivo. PKC inhibition did, however, significantly increase midgut barrier integrity and decrease development of P. falciparum oocysts in A. stephensi, suggesting that PKC-dependent signaling is a negative regulator of epithelial barrier function and a potential new target for transmission-blocking strategies
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