495 research outputs found

    NASA/DOD Aerospace Knowledge Diffusion Research Project. Report 12: An initial investigation into the production and use of Scientific and Technical Information (STI) at five NASA centers: Results of a telephone survey

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    A study was conducted to provide NASA management with an 'initial' look at the production and use of scientific and technical information (STI) at five NASA centers (Ames, Goddard, Langley, Lewis, and Marshall). The 550 respondents who were interviewed by telephone held favorable views regarding the NASA STI system. About 65 percent of the respondents stated that it is either very or somewhat important for them to publish their work through the NASA STI system. About 10 percent of those respondents encountered problems using the NASA STI system services for publication. The most frequently reported problem was 'the process is too time consuming' (8.6 percent). Overall, those respondents using the NASA STI system to publish their work rated the system as excellent (24.6 percent) or good (37.6 percent). About 79 percent of the respondents stated that it is either very or somewhat important for them to use the NASA STI system to access information. The most frequently reported problems were 'the time and effort it takes to locate and obtain information through the system' (14.4 percent). Overall, about 83 percent of the respondents stated that the NASA STI system is important to performing their work. Overall, about 73 percent of the respondents stated that the NASA STI system meets their information needs

    NASA/DOD Aerospace Knowledge Diffusion Research Project. Report 13: Source selection and information use by US aerospace engineers and scientists: Results of a telephone survey

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    A telephone survey of U.S. aerospace engineers and scientists belonging to the Society of Automotive Engineers (SAE) was conducted between December 4, 1991 and January 5, 1992. The survey was undertaken to (1) validate the telephone survey as an appropriate technique for collecting data from U.S. aerospace engineers and scientists; (2) collect information about how the results of NASA/DoD aerospace research are used in the R&D process; (3) identify those selection criteria which affect the use of federally-funded aerospace R&D; and (4) obtain information that could be used to develop a self-administered mail questionnaire for use with the same population. The average rating of importance of U.S. government technical reports was 2.5 (on a 4-point scale); The mean/median number of times U.S. government technical reports were used per 6 months was 8/2. Factors scoring highest for U.S. government technical reports were technical accuracy (2.9), reliable data and technical information (2.8), and contains comprehensive data and information (2.7) on a 4-point system. The factors scoring highest for influencing the use of U.S. government technical reports were relevance (3.1), technical accuracy (3.06), and reliable data/information (3.02). Ease of use, familiarity, technical accuracy, and relevance correlated with use of U.S. government technical reports. Survey demographics, survey questionnaire, and the NASA/DoD Aerospace Knowledge Diffusion Research Project publications list are included

    Ultrastructural, Cytochemical, and Immunocytochemical Studies on Bone and its Interfaces

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    Bone cells possess the ability to synthesize, secrete and direct the assembly and maintenance of extracellular matrix to form a functionally rigid and/or weight-bearing mineralized tissue complex, the skeleton. The skeleton not only supports and protects the organs and tissues of the body, but also acts as a mineral ion reservoir for maintaining systemic calcium balance (calcium homeostasis). The remarkable biological precision necessary for the formation, turnover and constant adaptation of bone to external mechanical forces is a dynamic process requiring a coordinated cellular effort relying on a variety of cell-cell and cell-matrix/mineral interactions. Indeed, cell-matrix interfaces found in a variety of locations in bone are sites potentially rich in signalling mechanisms related to bone modeling and remodeling. Detailed examination of the structure, composition and function of bone cells, and the extracellular matrix they produce and continuously remodel, is a complex task for such a mineralized tissue and requires integration and correlation of data from numerous sources. Various morphological approaches have added significantly to our understanding of bone form and function, and have allowed us to partly unravel some of the complex cellmatrix-mineral associations that occur during osteogenesis. In this context, the present article reviews some of our recent ultrastructural, cytochemical and immunocytochemical data on mammalian and avian intramembranous and endochondral bone formation (modeling) and turnover (remodeling)

    High-Resolution Scanning Electron Microscopy of Rat Incisor Ameloblasts

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    The internal three-dimensional organization of secretory and maturation stage ameloblasts was examined using field emission scanning electron microscopy. Particular attention was given to the structure of the Golgi apparatus, the distribution of smooth membrane tubulo-vesicular elements and their relationship with endosomal/lysosomal components. Rat incisors were fixed by intracardiac perfusion with glutaraldehyde, decalcified and divided into segments. The tissues were cryoprotected with glycerol and freeze-fractured. They were then macerated in osmium, and after conductive staining with osmium/tannic acid, the samples were critical-point dried and sputtered with gold. High-resolution scanning electron microscopy showed that ameloblasts contain a well-developed Golgi apparatus, even in the maturation stage where cells are generally believed not to be actively involved in protein secretion. Smooth tubulo-vesicular structures formed a complex network which extended throughout the cell. In secretory stage ameloblasts, this network reached into Tomes\u27 process and consisted of small and large tubules, and distended portions. The smaller tubules radiated from a central core of organelles towards the plasma membrane. Numerous lysosomal/endosomal elements were observed in the Golgi region, and in some cases smooth tubular portions were seen at the surface of multivesicular bodies. These data show that high-resolution scanning electron microscopy can be applied to correlate three-dimensional structural detail with the secretory and resorptive functions of ameloblasts

    University American Sign Language Learners: Longitudinal Self- and Faculty Evaluation Ratings

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    Students who are Deaf or hard of hearing (D/HH) represent a small yet diverse population of students with individual needs who often receive educational services provided by sign language interpreters and teachers of the Deaf/hard of hearing (D/HH). Many interpreters and teachers appear unprepared to model fluent American Sign Language (ASL) skills when working with D/HH students who use sign language for communication and instruction. We investigated the ASL skills of 19 interpreting and Deaf education candidates within one university preparation program at two points in time: the end of ASL I class (Time 1) and a year later at the end of ASL IV (Time 2). We used video recordings of candidatesā€™ signed renditions of a picture book, a rubric of 12 sign language indicators with five levels of proficiency across each indicator, and ratings conducted independently by the candidates and the five authors. Four of these authors were university professors in two different Deaf education/interpreting preparation programs and the fifth was a teacher at a residential school for the Deaf. Three have typical hearing and use ASL as a secondary language; two are Deaf and use ASL as their primary language. We compared candidatesā€™ self-ratings to those of the five authors. We found that candidates tended to over-estimate their skills at T1; self-ratings and author ratings increased from T1 to T2, and candidates had higher agreement with most authors at T2 compared to T1. In addition, we found differences among ratings between the university faculty and the high school teacher. We discuss these differences in our findings and address implications for evaluating and improving university candidatesā€™ ASL skills

    Influence of a Physiologically Formed Blood Clot on Pre-Osteoblastic Cells Grown on a BMP-7-Coated Nanoporous Titanium Surface

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    Titanium (Ti) nanotopography modulates the osteogenic response to exogenous bone morphogenetic protein 7 (BMP-7) in vitro, supporting enhanced alkaline phosphatase mRNA expression and activity, as well as higher osteopontin (OPN) mRNA and protein levels. As the biological effects of OPN protein are modulated by its proteolytic cleavage by serum proteases, this in vitro study evaluated the effects on osteogenic cells in the presence of a physiological blood clot previously formed on a BMP-7-coated nanostructured Ti surface obtained by chemical etching (Nano-Ti). Pre-osteoblastic MC3T3-E1 cells were cultured during 5 days on recombinant mouse (rm) BMP-7-coated Nano-Ti after it was implanted in adult female C57BI/6 mouse dorsal dermal tissue for 18 h. Nano-Ti without blood clot or with blood clot at time 0 were used as the controls. The presence of blood clots tended to inhibit the expression of key osteoblast markers, except for Opn, and rmBMP-7 functionalization resulted in a tendency towards relatively greater osteoblastic differentiation, which was corroborated by runt-related transcription factor 2 (RUNX2) amounts. Undetectable levels of OPN and phosphorylated suppressor of mothers against decapentaplegic (SMAD) 1/5/9 were noted in these groups, and the cleaved form of OPN was only detected in the blood clot immediately prior to cell plating. In conclusion, the strategy to mimic in vitro the initial interfacial in vivo events by forming a blood clot on a Ti nanoporous surface resulted in the inhibition of pre-osteoblastic differentiation, which was minimally reverted with an rmBMP-7 coating

    CFD parametric study of thermal performance of different fruit packaging box designs

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    Air temperature and relative humidity values of cold storage conditions are the major factor affecting the perishability of fresh fruits. The sooner the field heat is extracted from the products and the proper temperature is maintained consistency throughout the cold chain, larger it will be shelf life of these products. Forced air cooling is the most commonly used technique to remove the field heat in post-harvest storage. Energy-efficient and quality-oriented cold storage mainly depends on the time to remove the heat. This time can be reduced by optimizing the configuration of the vent holes of the packaging box, namely it dimension (area), it shape, alignment and position. This paper shows the numerical predictions of air temperature and velocity by a CFD parametric study of eight different vent hole configurations. These configurations consider a packaging box with double wall. The vent holes of each wall have different dimension and shape. The vent holes of both walls can be also aligned or unaligned. The analysis of results aims to determine the best configurations that improve the cooling rate, the airflow and temperature uniformity. The numerical predictions of the air temperature show close values, but three configurations can be identified as predicting the lowest air temperature values with lowest standard deviation. These results may help on the development of new configuration for fruit boxes that promote the extension of the fruits shelflife.(undefined

    NASA/DOD Aerospace Knowledge Diffusion Research Project. Report 15: Technical uncertainty and project complexity as correlates of information use by US industry-affiliated aerospace engineers and scientists: Results of an exploratory investigation

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    An exploratory study was conducted that investigated the influence of technical uncertainty and project complexity on information use by U.S. industry-affiliated aerospace engineers and scientists. The study utilized survey research in the form of a self-administered mail questionnaire. U.S. aerospace engineers and scientists on the Society of Automotive Engineers (SAE) mailing list served as the study population. The adjusted response rate was 67 percent. The survey instrument is appendix C to this report. Statistically significant relationships were found to exist between technical uncertainty, project complexity, and information use. Statistically significant relationships were found to exist between technical uncertainty, project complexity, and the use of federally funded aerospace R&D. The results of this investigation are relevant to researchers investigating information-seeking behavior of aerospace engineers. They are also relevant to R&D managers and policy planners concerned with transferring the results of federally funded aerospace R&D to the U.S. aerospace industry

    Effects of rmBMP-7 on Osteoblastic Cells Grown on a Nanostructured Titanium Surface

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    This study evaluates the effects of the availability of exogenous BMP-7 on osteoblastic cellsā€™ differentiation on a nanotextured Ti surface obtained by chemical etching (Nano-Ti). The MC3T3-E1 and UMR-106 osteoblastic cell lines were cultured for 5 and 7 days, respectively, on a Nano-Ti surface and on a control surface (Control-Ti) in an osteogenic medium supplemented with either 40 or 200 ng/mL recombinant mouse (rm) BMP-7. The results showed that MC3T3-E1 cells exhibited distinct responsiveness when exposed to each of the two rmBMP-7 concentrations, irrespective of the surface. Even with 40 ng/mL rmBMP-7, important osteogenic effects were noticed for Control-Ti in terms of cell proliferation potential; Runx2, Osx, Alp, Bsp, Opn, and Smad1 mRNA expression; and in situ ALP activity. For Nano-Ti, the effects were limited to higher Alp, Bsp, and Opn mRNA expression and in situ ALP activity. On both surfaces, the osteogenic potential of UMR-106 cultures remained unaltered with 40 ng/mL rmBMP-7, but it was significantly reduced when the cultures were exposed to the 200 ng/mL concentration. The availability of rmBMP-7 to pre-osteoblastic cells at the concentrations used alters the expression profile of osteoblast markers, indicative of the acquisition of a more advanced stage of osteoblastic differentiation. This occurs less pronouncedly on the nanotextured Ti and without reflecting in higher mineralized matrix production by differentiated osteoblasts on both surfaces

    Analysis of De Novo HOXA 13 Polyalanine Expansions Supports Replication Slippage Without Repair in Their Generation

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    Polyalanine repeat expansion diseases are hypothesized to result from unequal chromosomal recombination, yet mechanistic studies are lacking. We identified two de novo cases of handā€footā€genital syndrome (HFGS) associated with polyalanine expansions in HOXA13 that afforded rare opportunities to investigate the mechanism. The first patient with HFGS was heterozygous for a de novo nine codon polyalanine expansion. Haplotype investigation showed that the expansion arose on the maternally inherited chromosome but not through unequal crossing over between homologs, leaving unequal sister chromatid exchange during mitosis or meiosis or slipped mispairing as possible explanations. The asymptomatic father of the second patient with HFGS was mosaic for a six codon polyalanine expansion. Multiple tissue PCR and clonal analysis of paternal fibroblasts showed only expansion/WT and WT/WT clones, and haplotype data showed that two unaffected offspring inherited the same paternal allele without the expansion, supporting a postzygotic origin. Absence of the contracted allele in the mosaic father does not support sister chromatid exchange in the origin of the expansion. Mosaicism for HOXA13 polyalanine expansions may be associated with a normal phenotype, making examination of parental DNA essential in apparently de novo HFGS cases to predict accurate recurrence risks. We could not find an example in the literature where unequal sister chromatid exchange has been proven for any polyalanine expansion, suggesting that the principal mechanism for polyalanine expansions (and contractions) is slipped mispairing without repair or that the true frequency of unequal sister chromatid exchange involving these repeats is low. Ā© 2013 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97454/1/ajmga35843.pd
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