240 research outputs found

    Automated user modeling for personalized digital libraries

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    Digital libraries (DL) have become one of the most typical ways of accessing any kind of digitalized information. Due to this key role, users welcome any improvements on the services they receive from digital libraries. One trend used to improve digital services is through personalization. Up to now, the most common approach for personalization in digital libraries has been user-driven. Nevertheless, the design of efficient personalized services has to be done, at least in part, in an automatic way. In this context, machine learning techniques automate the process of constructing user models. This paper proposes a new approach to construct digital libraries that satisfy user’s necessity for information: Adaptive Digital Libraries, libraries that automatically learn user preferences and goals and personalize their interaction using this information

    Free Iron Distribution in Some Poorly Drained Prairie Soils in Iowa

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    In classification and mapping of soils an interpretation of the natural drainage characteristics of the soil types is usually made. Some standard natural drainage classes used are poorly drained, imperfectly drained, moderately well- drained, and well-drained (1). Interpretation of the natural drainage of the soils is important from the agronomic standpoint, and also is basic to the soil classification scheme in present use. The natural drainage of a soil is interpreted mainly by inferences from the color and mottling of hydrated iron oxides in the subsoil. Few studies have been made of the nature and quantity of these iron oxides in soils. Extractable iron or free iron has been determined in a few well-drained Brunizem and Gray Brown Podzolic soils, and in several poorly drained Forested Planosols (2) (3) (4) (5). The purpose of this paper is to report data on free iron in several poorly drained prairie (Wiesenboden) soils and to compare these data with available data of other great soil groups in Iowa

    Discovery of a Nova-Like Cataclysmic Variable in the Kepler Mission Field

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    We announce the identification of a new cataclysmic variable star in the field of the Kepler Mission, KIC J192410.81+445934.9. This system was identified during a search for compact pulsators in the Kepler field. High-speed photometry reveals coherent large-amplitude variability with a period of 2.94 h. Rapid, large-amplitude quasi-periodic variations are also detected on time scales of ~1200 s and ~650 s. Time-resolved spectroscopy covering one half photometric period shows shallow, broad Balmer and He I absorption lines with bright emission cores as well as strong He II and Bowen blend emission. Radial velocity variations are also observed in the Balmer and He I emission lines that are consistent with the photometric period. We therefore conclude that KIC J192410.81+445934.9 is a nova-like variable of the UX UMa class in or near the period gap, and it may belong to the rapidly growing subclass of SW Sex systems. Based on 2MASS photometry and companion star models, we place a lower limit on the distance to the system of ~500 pc. Due to limitations of our discovery data, additional observations including spectroscopy and polarimetry are needed to confirm the nature of this object. Such data will help to further understanding of the behavior of nova-like variables in the critical period range of 3-4 h, where standard cataclysmic variable evolutionary theory finds major problems. The presence of this system in the Kepler mission field-of-view also presents a unique opportunity to obtain a continuous photometric data stream of unparalleled length and precision on a cataclysmic variable system.Comment: Accepted for publication in the Astronomical Journal. 8 pages, 7 figures, uses emulateapj

    Recording fine‐scale movement of ground beetles by two methods: Potentials and methodological pitfalls

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    Movement trajectories are usually recorded as a sequence of discrete movement events described by two parameters: step length (distance) and turning angle (bearing). One of the most widespread methods to record the geocoordinates of each step is by a GPS device. Such devices have limited suitability for recording fine movements of species with low dispersal ability including flightless carabid beetles at small spatio‐temporal scales. As an alternative, the distance‐bearing approach can avoid the measurement error of GPS units since it uses directly measured distances and compass azimuths. As no quantification of measurement error between distance‐bearing and GPS approaches exists so far, we generated artificial fine‐scale trajectories and in addition radio‐tracked living carabids in a temperate forest and recorded each movement step by both methods. Trajectories obtained from distance‐bearing were compared to those obtained by a GPS device in terms of movement parameters. Consequently, both types of trajectories were segmented by state‐switching modeling into two distinct movement stages typical for carabids: random walk and directed movement. We found that the measurement error of GPS compared to distance‐bearing was 1.878 m (SEM = 0.181 m) for distances and 31.330° (SEM = 2.066°) for bearings. Moreover, these errors increased under dense forest canopy and rainy weather. Distance error did not change with increasing distance recorded by distance‐bearing but bearings were significantly more sensitive to error at short distances. State‐switching models showed only slight, not significant, differences in movement states between the two methods in favor of the random walk in the distance‐bearing approach. However, the shape of the GPS‐measured trajectories considerably differed from those recorded by distance‐bearing caused especially by bearing error at short distances. Our study showed that distance‐bearing could be more appropriate for recording movement steps not only of ground‐dwelling beetles but also other small animals at fine spatio‐temporal scales

    Integration of decision support systems to improve decision support performance

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    Decision support system (DSS) is a well-established research and development area. Traditional isolated, stand-alone DSS has been recently facing new challenges. In order to improve the performance of DSS to meet the challenges, research has been actively carried out to develop integrated decision support systems (IDSS). This paper reviews the current research efforts with regard to the development of IDSS. The focus of the paper is on the integration aspect for IDSS through multiple perspectives, and the technologies that support this integration. More than 100 papers and software systems are discussed. Current research efforts and the development status of IDSS are explained, compared and classified. In addition, future trends and challenges in integration are outlined. The paper concludes that by addressing integration, better support will be provided to decision makers, with the expectation of both better decisions and improved decision making processes

    Oppilaitten eettinen toimijuus videotutkimuksessa

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    The rapid development of various recording technologies in recent years has created appealing opportunities for researchers to document and study science, technology, engineering, and mathematics (STEM) learning in ways which previously were either impossible, high-priced, or impractical. The potential access that low-cost and ever-smaller recorders provide us has been wisely tempered with cautions that researchers critically reflect on whether the benefits of the research outweigh the invasion of participants’ privacy, especially in research with children. These cautions rightfully place the burden of ethical deliberation on the researcher. However, by so doing they also direct attention away from the ethical work done by study participants and overshadow their agency in relation to the research. In effect, the cautions join and reinforce dominant narratives of participant, especially children’s, vulnerability in research and the researcher as the main ethical actor during the research process. This study seeks to balance such narratives by drawing attention to how children demonstrate their awareness of the audience of nearby recorders to each other and, through such actions, also create spaces for private, out-of-view interaction they do not wish to be recorded. With demonstrative vignettes from a yearlong ethnographic study of children’s learning in an alternative STEM learning infrastructure, the study argues that such moments highlight children’s ethical agency in research.The rapid development of various recording technologies in recent years has created appealing opportunities for researchers to document and study science, technology, engineering, and mathematics (STEM) learning in ways which previously were either impossible, high-priced, or impractical. The potential access that low-cost and ever-smaller recorders provide us has been wisely tempered with cautions that researchers critically reflect on whether the benefits of the research outweigh the invasion of participants’ privacy, especially in research with children. These cautions rightfully place the burden of ethical deliberation on the researcher. However, by so doing they also direct attention away from the ethical work done by study participants and overshadow their agency in relation to the research. In effect, the cautions join and reinforce dominant narratives of participants’, especially children’s, vulnerability in research and the researcher as the main ethical actor during the research process. This study seeks to balance such narratives by drawing attention to how children demonstrate their awareness of the audience of nearby recorders to each other and, through such actions, also create spaces for private, out-of-view interaction they do not wish to be recorded. With demonstrative vignettes from a yearlong ethnographic study of children’s learning in an alternative STEM learning infrastructure, the study argues that such moments highlight children’s ethical agency in research.Peer reviewe

    A Developmental Perspective on Community Service in Adolescence

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    A substantial number of U.S. adolescents currently participate in community service and there is increased national interest in service programs. This article assesses the assumption of developmental benefits to service participants by critically reviewing 44 empirical studies. It offers a theoretical framework for understanding the findings by connecting them to identity development and delineating three pertinent concepts: agency, social relatedness, and moral-political awareness. These concepts are applied to studies that investigate: ( 1) the characteristics and motivations of participants, ( 2) the effects of service, and ( 3) the process of service. The findings support the conclusion that service activities which provide opportunities for intense experiences and social interactions are often associated with prosocial development. The findings also point to the need for more studies focused on particular service programs and on relationships between service providers and those served

    FasL is more frequently expressed in liver metastases of colorectal cancer than in matched primary carcinomas

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    Colorectal carcinoma cells have recently been shown to express Fas ligand (FasL). This ligand could allow the tumour cells to evade activated tumour-infiltrating lymphocytes (TILs) by inducing their apoptosis and would thus promote tumour survival and possibly metastasis formation. To test this hypothesis in vivo we analysed the expression of FasL mRNA and protein in paired tissue samples of normal colonic mucosa (N), primary colorectal carcinomas (T) and their metastases (M) from a total of 21 patients by four different methods. Additionally, the presence and activation status of infiltrating lymphocytes, which might contribute to the total amount of FasL in the tissue, was determined by semiquantitative reverse transcription–polymerase chain reaction (RT–PCR) in the same samples. The frequency of FasL detection was 30–40% in T and was 60–100% in M, depending on the sensitivity of the method. Simultaneously, the amount of CD25 mRNA, used as a measure of the number of activated TILs, was in 90% of patients lower in M than in T. The increased frequency of FasL detection in liver metastases was therefore not due to the presence of activated TILs. We conclude that metastasizing subpopulations of colorectal tumour cells express FasL more frequently than the primary carcinomas and may be able to eliminate activated TILs in vivo via Fas/FasL-induced apoptosis or other hitherto unknown mechanisms. © 1999 Cancer Research Campaig
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