15,361 research outputs found

    Family visits to libraries and bookshops: observations and implications for digital libraries

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    This paper explores how families select books for leisure reading. We recruited 17 families (adults and children) for this study, and spent time with each in both bookshops and public libraries. Our research aims to add to understanding of how families interact with books and bookshelves in these places, and how digital libraries might best support the shared needs of these inter-generational users. Much of our understanding of how an eBook should look and feel comes from generalizations about books and assumptions about the needs of those individuals who read them. We explore how children and adults search and browse for books together, with specific focus on the type of information seeking tasks that families undertake and on the familiesā€™ shared search and browsing strategies. We further explore the implications of this study for the development of digital libraries for children and families

    Radial glia in the proliferative ventricular zone of the embryonic and adult turtle, Trachemys scripta elegans.

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    To better understand the role of radial glial (RG) cells in the evolution of the mammalian cerebral cortex, we investigated the role of RG cells in the dorsal cortex and dorsal ventricular ridge of the turtle, Trachemys scripta elegans. Unlike mammals, the glial architecture of adult reptile consists mainly of ependymoradial glia, which share features with mammalian RG cells, and which may contribute to neurogenesis that continues throughout the lifespan of the turtle. To evaluate the morphology and proliferative capacity of ependymoradial glia (here referred to as RG cells) in the dorsal cortex of embryonic and adult turtle, we adapted the cortical electroporation technique, commonly used in rodents, to the turtle telencephalon. Here, we demonstrate the morphological and functional characteristics of RG cells in the developing turtle dorsal cortex. We show that cell division occurs both at the ventricle and away from the ventricle, that RG cells undergo division at the ventricle during neurogenic stages of development, and that mitotic Tbr2+ precursor cells, a hallmark of the mammalian SVZ, are present in the turtle cortex. In the adult turtle, we show that RG cells encompass a morphologically heterogeneous population, particularly in the subpallium where proliferation is most prevalent. One RG subtype is similar to RG cells in the developing mammalian cortex, while 2 other RG subtypes appear to be distinct from those seen in mammal. We propose that the different subtypes of RG cells in the adult turtle perform distinct functions

    Health Research Participants' Preferences for Receiving Research Results

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    BACKGROUND: Participants in health research studies typically express interest in receiving results from the studies in which they participate. However, participantsā€™ preferences and experiences related to receiving results are not well understood. In general, existing studies have had relatively small sample sizes and typically address specific and often sensitive issues within targeted populations. METHODS: The present study used an online survey to explore attitudes and experiences of registrants in ResearchMatch, a large database of past, present, and potential health research participants. Survey respondents provided information related to whether or not they received research results from studies in which they participated, the methods used to communicate results, their satisfaction with results, and when and how they would like to receive research results from future studies. 70,699 ResearchMatch registrants were notified of the studyā€™s topic. Of the 5,207 registrants who requested full information about the study, 3,381 respondents completed the survey. RESULTS: Approximately 33% of respondents with previous health research participation reported receiving results. Approximately half of respondents with previous research participation reported no opportunity to request results. However, almost all respondents said researchers should always or sometimes offer results to participants. Respondents expressed particular interest in results related to their (or a loved one's) health, as well as information about studiesā€™ purposes and any medical advances based on the results. In general, respondentsā€™ most preferred dissemination methods for results were email and website postings. The least desirable dissemination methods for results included Twitter, conference calls, and text messages. Across all results, we compare the responses of respondents with and without previous research participation experience, and those who have worked in research organizations vs. those who have not. Compared to respondents who have previous participation experience, a greater proportion of respondents with no participation experience indicated that results should always be shared with participants. Likewise, respondents with no participation experience placed higher importance on the receipt of each type of results information included in the survey. CONCLUSIONS: We present findings from a survey assessing attitudes and experiences of a broad sample of respondents that addresses gaps in knowledge related to participantsā€™ preferences for receiving results. The studyā€™s findings highlight the potential for inconsistency between respondentsā€™ expressed preferences to receive specific types of results via specific methods and researchersā€™ unwillingness or inability to provide them. We present specific recommendations to shift the approach of new studies to investigate participantsā€™ preferences for receiving research results

    The calibration of photographic and spectroscopic films: Reciprocity failure and thermal responses of IIaO film at liquid nitrogen temperatures

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    Reciprocity failure was examined for IIaO spectroscopic film. The results indicate reciprocity failure occurs at three distinct minimum points in time; 15 min, 30 min and 90 min. The results are unique because theory suggests only one minimum reciprocity failure point should occur. When incubating 70mm IIaO film for 15 and 30 min at temperatures of 30, 40, 50, and 60 C and then placing in a liquid nitrogen bath at a temperature of -190 C the film demonstrated an increase of the optical density when developed at a warm-up time of 30 min. Longer warm-up periods of 1, 2 and 3 hrs yield a decrease in optical density of the darker wedge patterns; whereas, shorter warm-up times yield an overall increase in the optical densities

    Solar Electric Propulsion Vehicle Demonstration to Support Future Space Exploration Missions

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    Human and robotic exploration beyond Low Earth Orbit (LEO) will require enabling capabilities that are efficient, affordable, and reliable. Solar Electric Propulsion (SEP) is highly advantageous because of its favorable in-space mass transfer efficiency compared to traditional chemical propulsion systems. The NASA studies have demonstrated that this advantage becomes highly significant as missions progress beyond Earth orbit. Recent studies of human exploration missions and architectures evaluated the capabilities needed to perform a variety of human exploration missions including missions to Near Earth Objects (NEOs). The studies demonstrated that SEP stages have potential to be the most cost effective solution to perform beyond LEO transfers of high mass cargoes for human missions. Recognizing that these missions require power levels more than 10X greater than current electric propulsion systems, NASA embarked upon a progressive pathway to identify critical technologies needed and a plan for an incremental demonstration mission. The NASA studies identified a 30kW class demonstration mission that can serve as a meaningful demonstration of the technologies, operational challenges, and provide the appropriate scaling and modularity required. This paper describes the planning options for a representative demonstration 30kW class SEP mission

    Advanced tracking systems design and analysis

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    The results of an assessment of several types of high-accuracy tracking systems proposed to track the spacecraft in the National Aeronautics and Space Administration (NASA) Advanced Tracking and Data Relay Satellite System (ATDRSS) are summarized. Tracking systems based on the use of interferometry and ranging are investigated. For each system, the top-level system design and operations concept are provided. A comparative system assessment is presented in terms of orbit determination performance, ATDRSS impacts, life-cycle cost, and technological risk

    A Histological Assessment of the Reproductive Cycle of the Sea Urchin, Lytechinus variegatus

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    The regular echinoid Lytechinus variegatus is a valuable model for the study of early embryological development. Lytechinus variegatus inhabits nearshore seagrass beds in the Gulf of Mexico and Caribbean, and the species ranges from the Carolinas along the US Atlantic coast to Brazil. Evaluating the natural reproductive cycle of L. variegatus will aid in understanding its role in community structure and in the management of this resource when housed in the laboratory. From April 2001 to September 2003, at intervals of 4ā€”6 weeks, L. variegatus (41āˆ’50 mm diameter; n = 32 individuals/collection) were collected at Eagle Harbor in St. Josephā€™s Bay, FL. A histological staging system for gamete development and maturation of the gonad was devised for female and male L. variegatus. The annual minimum gonad index was observed in September or October and increased to a maximum in March or April. A period of nutrient storage and limited gametogenic activity along the germinal epithelium in the fall and winter preceded spring gamete production and maturation. Observations of the mature reproductive stage in L. variegatus were associated with the new and full moon, suggesting that lunar cycle or tides influenced the timing of spawning. Peak periods of spawning occurred in spring and, occasionally, in the summer. Spawning probably did not occur from October to January. These data indicate field collections can be timed for early spring to ensure gravid adults for developmental studies
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