Showing papers by "Virginia Tech published in 1995"

Book review: a dynamic systems approach to the development of cognition and action by, esther thelen and linda b. smith, cambridge, ma: The mit press, 1994, hardbound, 376 pages, $50.00. isbn 0-262-70059-x

Abstract: Life, said the English novelist Samuel Butler, is like giving a concert on the violin while learning to play the instrument. Butler's insight-that there are no distinct training and performance modes in development succinctly captures the activity-dependent nature of the developmental process. For example, imagine a baby learning to walk. Although babies spend a great deal of time failing down, getting up, and falling down again, as far as some parents are concerned, their child's walking seems to magically appear de novo one day. Other parents, however, do appreciate the importance of their baby's ups and downs and believe the old saying that practice makes perfect" in the emergence of walking. Butler's insight, however, suggests a third perspective on the emergence of such novel behavior: namely, that there are no practice modes in development-all activity counts in selecting, constructing, and maintaining behavioral outcomes. This fundamental role that self-generated activity plays in the development of all behavioral functions, ranging from motor behavior to perception, cognition, and social behavior, is a central theme of the dynamic systems approach that is masterfully explicated in the recent book by Esther Thelen and Linda B. Smith. In this book the authors (both developmental psychologists) apply the principles of nonlinear dynamic systems to motor, perceptual, and cognitive development and the result is a remarkable synthesis and advancement of developmental science. Indeed, it would not be an exaggeration to say that this volume offers a revolutionary perspective on the development of cognition and action.

Scenario-based design: envisioning work and technology in system development

Abstract: Partial table of contents: Work Processes: Scenarios as a Preliminary Vocabulary (K. Kuutti). Creating Contexts for Design (M. Kyng). Scenario Use in the Design of a Speech Recognition System (J. Karat). Usage Representations for Reuse of Design Insights: A Case Study of Access to On-Line Books (T. Carey & M. Rusli). Design Space Analysis and Use Representations (A. MacLean & D. McKerlie). Rapid Prototyping of User Interfaces Driven by Task Models (P. Johnson, et al.). Generating Object-Oriented Design Representations via Scenario Queries (S. Robertson). The Use-Case Construct in Object-Oriented Software Engineering (I. Jacobson). Discussion: Scenarios as Engines of Design (R. Mack). Some Reflections on Scenarios (B. Nardi). Index.

Digital libraries

Abstract: ing Education-support Object-oriented Accessibility Electronic publishing OCR Agents Ethnographic study OODB support Annotation Filtering Personalization Archive Geographic information system Preservation Billing, charging Hypermedia Privacy Browsing Hypertext Publisher library Catalog Image processing Repository Classification Indexing Scalability Clustering Information retrieval Searching Commercial service Intellectual property rights Security Content conversion Interactive Sociological study Copyright clearance Knowledge base Storage Courseware Knowbot Standard Database Library science Subscription Diagrams (e.g., CAD) Mediator Sustainability Digital video Multilingual Training support Discipline-level library Multimedia stream playback Usability Distributed processing Multimedia systems Virtual (integration) Document analysis Multimodal Visualization Document model National library World-Wide Web Economic study Navigation its characterization of digital libraries. Many important projects and perspectives have been omitted. Here we give some pointers to aid further exploration, and of course we encourage interested readers to attend the numerous conferences and workshops scheduled in this field, many sponsored by or in cooperation with ACM and its SIGs. One early journal special issue is introduced in [6]. It includes articles on copyright and intellectual property rights, a subscription model for handling funds transfer related to digital libraries, a description of the evolution of the WAIS search system in general and its interfaces in particular, an overview of the Right Pages system and its use of OCR and document analysis algorithms, and an early overview of the Envision system [7]. We note that to many, intellectual property rights issues and ways to obtain revenue streams to sustain digital libraries are the most important open problems. The largest digital library conference makes its proceedings available over the WWW [9]. These contain many insightful discussions, proposals of new research ideas, descriptions of base technologies, and explanations of how the broad concept of a digital library fits in with the needs of specific user communities and the information they require. Readers can find a variety of works on agents, architectures, catalogs, collaboration, compression, document analysis from OCR and page images, document structure, electronic journals, heterogeneous sources, knowledge-based approaches, library science, numerical data collections, object stores, and organizational usability. For more details on the origins of the Digital Library Initiative, and for a variety of perspectives on open research problems, we refer the reader to [5]. This work also has numerous pointers to people, projects, institutions, and other reference works in the area. For a perspective on the role the computer industry should have in this field, see [10]. This report outlines IBM’s perspective on key supporting technologies and on the unique challenges highlighted by the emergence of digital libraries. We expect considerable interest from the corporate sector as well as from government agencies in this important area of information technology. For lack of space, we have had to omit many publications on networking and storage technologies, sociological and ethnographic studies, library and information science, OCR and document analysis or conversion, and rights management. These and other works are needed to round out the discussion of digital libraries. However, we encourage you to read the rest of this issue as a good starting point for your future studies of this important field. We invite you to not only use but also help in the creation of a future World Digital Library System!

Analysis of Arabidopsis mutants deficient in flavonoid biosynthesis.

Abstract: Eleven loci that play a role in the synthesis of flavonoids in Arabidopsis are described. Mutations at these loci, collectively named transparent testa (tt), disrupt the synthesis of brown pigments in the seed coat (testa). Several of these loci (tt3, tt4, tt5 and ttg) are also required for the accumulation of purple anthocyanins in leaves and stems and one locus (ttg) plays additional roles in trichome and root hair development. Specific functions were previously assigned to tt1-7 and ttg. Here, the results of additional genetic, biochemical and molecular analyses of these mutants are described. Genetic map positions were determined for tt8, tt9 and tt10. Thin-layer chromatography identified tissue- and locus-specific differences in the flavonols and anthocyanidins synthesized by mutant and wild-type plants. It was found that UV light reveals distinct differences in the floral tissues of tt3, tt4, tt5, tt6 and ttg, even though these tissues are indistinguishable under visible light. Evidence was also uncovered that tt8 and ttg specifically affect dihydroflavonol reductase gene expression. A summary of these and previously published results are incorporated into an overview of the genetics of flavonoid biosynthesis in Arabidopsis.

Intestinal floras of populations that have a high risk of colon cancer.

Abstract: The fecal floras of polyp patients, Japanese-Hawaiians, North American Caucasians, rural native Japanese, and rural native Africans were compared. The polyp patients and Japanese-Hawaiians were considered to be groups at high risk of colon cancer, and the rural native Japanese and rural native Africans were considered to be groups at low risk. The North American Caucasians were found to have a flora composition intermediate between these two groups. Fifteen bacterial taxa from the human fecal flora were significantly associated with high risk of colon cancer, and five were significantly associated with low risk of colon cancer. Total concentrations of Bacteroides species and, surprisingly, Bifidobacterium species were generally positively associated with increased risk of colon cancer. Some Lactobacillus species and Eubacterium aerofaciens, which also produces major amounts of lactic acid, showed closest associations with low risk of colon cancer.

Statistical mechanics of driven diffusive systems

Abstract: Publisher Summary This chapter discusses the systems coupled to two reservoirs of energy in such a way that there is a steady energy flow through the system. An example is a resistor in steady state, gaining energy from a battery and losing it to the atmosphere. Even for this restricted class there is no equivalent of Gibbs' framework and, typically, distributions cannot be expressed solely in terms of the internal energies of the system. Thus, in addition to the “technical difficulties” associated with computing averages in a many-body system, one must first solve the “more fundamental” problem of finding the stationary distribution. For systems, which are only weakly perturbed so that they remain “close to equilibrium,” much is known at the level of linear response. The chapter focuses on steady states “far from equilibrium” where such schemes break down. Against this backdrop of a vast theoretical terra incognita, a reasonable approach consists in investigating systems which, while retaining the essence of the difficulties of “far from equilibrium” states, are as simple as possible. In this very spirit, Lenz suggested the Ising model in an attempt to understand the nature of ferromagnetic phase transitions. This philosophy provides one of the main motivations behind the introduction of a simple non-equilibrium system, which is referred to as the “standard model.”

First measurement of the rate for the inclusive radiative penguin decay b→sγ

Abstract: We have measured the inclusive {ital b}{r_arrow}{ital s}{gamma} branching ratio to be (2.32{plus_minus}0.57{plus_minus}0.35){times}10{sup {minus}4}, where the first error is statistical and the second is systematic. Upper and lower limits on the branching ratio, each at 95% C.L., are {ital B}({ital b}{r_arrow}{ital s}{gamma}){lt}4.2{times}10{sup {minus}4} and {ital B}({ital b}{r_arrow}{ital s}{gamma}){gt}1.0{times}10{sup {minus}4}. These limits restrict the parameters of extensions of the standard model.

Competitiveness through Management of Diversity: Effects on Stock Price Valuation

Abstract: This study's premise is that firms that can lower their costs and enhance their differentiation through the effective management of their human resources have a competitive advantage. Using data fr...

The Effects of Four Components of Parental Involvement on Eighth-Grade Student Achievement: Structural Analysis of NELS-88 Data

Abstract: The present research was undertaken to assess the effects of different components of parental involvement on the academic achievement of eighth graders. Four components of parental involvement cons...

Truss Structure Integrity Identification Using PZT Sensor-Actuator

Abstract: This paper presents a frequency domain impedance-signature-based technique for health monitoring of an assembled truss structure. Unlike conventional modal analysis approaches, the technique uses piezoceramic (PZT) elements as integrated sensor-actuators for acquisition of signature pattern of the truss. The concept of the localization of sensing/actuation area for damage detection of an assembled structure is presented for the first time. Through a PZT patch bonded to a truss node and the measurement of its electric admittance, which is coupled with the mechanical impedance of the truss, the signature pattern of a truss is monitored. The admittance of a truss in question is compared with that of the original healthy truss. Statistic algorithm is then applied to extract a damage index of the truss based on the signature pattern difference. Experimental proof that over a selected band, the detection range of a bonded PZT sensor on a truss is highly constrained to its immediate neighborhood is presented. This characteristic allows accurate determination of the damage location in a complex real-world structure with a minimum mathematical modeling and numerical computation.

Soft-switching techniques in PWM converters

Abstract: A number of soft-switching pulse-width-modulated (PWM) converter techniques have been proposed, aimed at combining the desirable features of both the conventional PWM and resonant converters while avoiding their respective limitations. In this paper, three classes of zero-voltage soft-switching (PWM) converters (namely the zero-voltage-switched (ZVS) quasi-square-wave converters, ZVS-PWM converters, and zero-voltage-transition PWM converters) and two classes of zero-current soft-switching PWM converters (namely, the zero-current-switched PWM converters and zero-current-transition PWM converters) are reviewed, and their merits and limitations are assessed. Experimental results of several prototype of converters are presented to illustrate each class of converter.

Combining the evidence of multiple query representations for information retrieval

Abstract: We report on two studies in the TREC-2 program that investigated the effect on retrieval performance of combination of multiple representations of TREC topics. In one of the projects, five separate Boolean queries for each of the 50 TREC routing topics and 25 of the TREC ad hoc topics were generated by 75 experienced online searchers. Using the INQUERY retrieval system, these queries were both combined into single queries, and used to produce five separate retrieval results for each topic. In the former case, progressive combination of queries led to progressively improving retrieval performance, significantly better than that of single queries, and at least as good as the best individual single-query formulations. In the latter case, data fusion of the ranked lists also led to performance better than that of any single list. In the second project, two automatically produced vector queries and three versions of a manually produced P-norm extended Boolean query for each routing and ad hoc topic were compared and combined. This project investigated six different methods of combination of queries, and the combination of the same queries on different databases. As in the first project, progressive combination led to progressively improving results, with the best results, on average, being achieved by combination through summing of retrieval status values. Both projects found that the best method of combination often led to results that were better than the best performing single query. The combined results from the two projects have also been combined by data fusion. The results of this procedure show that combining evidence from completely different systems also leads to performance improvement.

Ecological Attributes of Extinction-Prone Species: Loss of Freshwater Fishes of Virginia

Abstract: I examined patterns of extirpation among Virginia’s 197 historically native freshwater fish species to address the following questions: (1) Are extinction-prone species ecologically distinct? and (2) Are distinctive features similar to those identified for extinction-prone species in terrestrial systems? All species were assigned to categories for a series of attributes reflecting geographical distribution, habitat use, trophic habits, life history, size, and reproductive behavior. Associations between species that had been extirpated and those that had not were examined for each attribute. Univariate associations were observed between extirpation and three ecological attributes: diadromy, limited physiographic range, and limited range of water sizes. Species specialized with respect to multiple ecological attributes also were especially likely to be extirpated. These associations reflected the effects of reduced habitat area and increased isolation (insularization), which are also important determinants of extinction in terrestrial systems. Multivariate analyses suggested that extirpated species were ecologically similar to each other, but were not completely distinct from the nonextirpated fauna. My results suggest that ecological knowledge of species can help identify extinction-prone species and provide a basis for proactive conservation. Current approaches to conservation, which are largely reactive and piecemeal, are inadequate to protect biodiversity. Because aquatic degradation is complex and pervasive, conservation of aquatic biodiversity requires proactive comprehensive approaches to water resource management, including emphasis on protecting the ecological integrity of entire systems. Examine los patrones de extirpacion entre 197 especies de peces dulceacuicolas nativos con fin de considerar las siguientes preguntas: 1) ?Tienen las especies proclives a la extincion caracteristicas ecologicas distintivas? 2) ?Son estas caracteristicas distintivas semejantes aquellas identificadas en las especies terrestres proclives a las extinciones? Todas las especies fueron asignadas a categorias correspondientes a una serie de atributos que reflejan la distribucion geografica, el uso del habitat, los habitos troficos, la historia natural, el tamano y el comportamiento reproductivo. Para cada atributo, se examinaron las asociaciones entre especies que fueron extirpadas y aquellas que no lo fueron. Se observaron asociaciones univariadas entre la extirpacion y tres atributos ecologicos (diadromia, rango fisiografico limitado y limitado rango del tamano de los habitats acuaticos). Las especies especializadas con respecto a atributos ecologicos multiples tambien fueron especialmente proclives a la extirpacion. Estas asociaciones reflejaron los efectos de una superficie del habitat reducida y de un incremento del aislamiento (insularizacion), los cua es tambien son determinantes importantes de la extincion en ecosistemas terrestres. El analisis multivariado sugirio que las especies extirpadas eran ecologicamente similares entre si, pero no eran completamente distintas de la fauna no extripada. Mis resultados sugieren que el conocimiento ecologico de las especies puede ayudar a identificar especies proclives a la extincion y provee de una base para una conservacion con iniciativa. Las estrategias de conservacion actuales, que son en gran medida reactivas y puntuales, son inadecuadas para proteger la biodiversidad. Dado que la degradacion acuatica es compleja y omnipresente, la conservacion de la biodiversidad acuatica requiere estrategias de manejo de los recursos acuaticos comprensivas y con iniciativa, incluyendo un enfasis en la proteccion de la integridad ecologica de los sistemas en su totalidad.

Incorporating Prior Knowledge into the Analysis of Conjoint Studies

Abstract: The authors use conjoint analysis to provide interval-level estimates of part-worths allowing tradeoffs among attribute levels to be examined. Researchers often possess prior information about the ...

Automated real-time structure health monitoring via signature pattern recognition

Abstract: C. LiangDept. of Mechanical EngineeringSan Diego State UniversitySan Diego, CA 92182-0191ABSTRACTDescribed in this paper are the details of an automated real-time structure health monitoring system. The system is based onstructural signature pattern recognition. It uses an array ofpiezoceramic (PZ1) patches bonded to the structure as integratedsensor-actuators, an electric impedance analyzer for structural frequency response function (FRF) acquisition and a PC forcontrol and graphic display. An assembled 3-bay truss structure is employed as a test bed. Two issues, the localization ofsensing area and the sensor temperature drift, which are Critical for the sneess of this technique are addressed and a novelapproach of providing temperature compensation using probability correlation function is presentecL Due to the negligibleweight and size of the solid-state sensor array and its ability to sense incipient-type damage, the system can eventually beimplemented on many types of structures such as aircraft, spacecraft, large-span dome roof and steel bridges requiring multi-location and real-time health monitoring1. INTRODUCTIONNondestructive evaluation of structural integrity, or health monitoring, of important structures, such as truss-based sceframe, is of great interest to civil and spae engineering community. To date, many approahes based on modal analysis, orsystem identification have been investigated to assess the damage of a working truss. Most of them explore the fact thatdamage to truss member or its connections generally leads to changes in the modal stiffness matrix of the structure23 Yet,few of them exhibit engineering feasibility because of the low reliability in locating the damage and the requirement ofcomplicated modeling, intensive computation and sophisticated instrumentation.Examination of the mechanical impedance of a structure at the location of interest and comparing it with pre-saved data base

Citizen participation and emprowerment: The case of local environmental hazards

Abstract: Local environmental hazards place millions of citizens at risk of physical, emotional, and financial harm. While the discovery of such hazards can be fundamentally disempowering for individuals and communities, few scholars have examined the dynamics of empowerment in this context. We explore the relationships among forms of empowerment, citizen participation, and local environmental hazards, and offer a model of the processes of empowerment and disempowerment appropriate to a broad range of citizen issues. On the basis of this analysis we recommend a partnership approach to community decision making that is designed both to reduce the likelihood that local environmental hazards will develop and to minimize the disempowering impact of any threats that do occur.

Polarization-independent all-fiber wavelength-division multiplexer based on a Sagnac interferometer.

Abstract: An all-fiber wavelength-division multiplexer (WDM) based on the nonreciprocity of the birefringence to the polarization states is proposed. The transfer function of a Sagnac interferometer is wavelength dependent if the loop birefringence of the interferometer consists of both circular and linear parts. Theoretical analysis shows that the output characteristics of this WDM are similar to those of a fiber taper-based device. Both the bandwidth and the peak wavelength of the new WDM can be tuned by changing the loop birefringence. Experimental prototypes exhibit a channel isolation greater than 25 dB with peak passband insertion loss of less than 1 dB.

Dietary chromium picolinate additions improve gain:feed and carcass characteristics in growing-finishing pigs and increase litter size in reproducing sows.

Abstract: Growth trials were conducted to determine the effects of Cr as chromium picolinate at various protein levels on performance of growing pigs The effects of continued supplementation on sow fecundity and body weight changes through two parities also were examined In Trial 1, 48 crossbred pigs (409 kg initial weight) were assigned to one of three diets (0, 250, or 500 ppb of added Cr) The only observed difference was an overall trend for an improvement in gain:feed when Cr was added to the diet (P < 10) In Trial 2, 105 crossbred pigs (145 kg initial weight) were assigned to one of seven treatments involving a combination of two factors: 1) lysine level at 100 or 120% of NRC (1988) requirement estimate and 2) added Cr level (0, 100, 200, 500, or 1,000 ppb) A Cr x lysine interaction (P < 02) for gain:feed existed that demonstrated that the addition of 200 ppb of Cr resulted in improved gain:feed at the 100% of requirement lysine level but not at the 120% of requirement lysine level The addition of 200 ppb Cr also reduced backfat (P < 04) and increased longissimus muscle area (P < 04) regardless of lysine level in the diet(ABSTRACT TRUNCATED AT 250 WORDS)

Aging Well With Friends and Family.

Abstract: Aging encourages people to enhance their friend and family relationships. In general, the elderly tend to have more heterogeneity in relationships as they grow older. They depend on these relationships for instrumental, financial and emotional support. As a result, older adults who have many friends and have close ties with their families are more socially and psychologically well-adjusted than those who are alienated from their networks.

Textural evolution of synthetic fluid inclusions in quartz during reequilibration, with applications to tectonic reconstruction

Abstract: Experimental reequilibration of synthetic 10 wt% NaCl-H2O inclusions in natural quartz reveals that reequilibration textures show distinct differences depending upon the P-T path followed by the inclusion after formation. These differences combined with other geological information may be used to determine whether the sample (rock) followed a dominantly isothermal or isobaricP-T path following entrapment. The intensity and style of inclusion reequilibration features is related to the direction and magnitude of the departure of theP-T path from the original isochore for the inclusion. Thus, fluid inclusion reequilibration textures not only permit inclusionists to determine whether the rocks followed an isothermal or isobaric retrogradeP-T path, but also the magnitude of departure of this path from one that is isochoric.