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Showing papers by "Rensselaer Polytechnic Institute published in 2000"


Journal ArticleDOI
Donald G. York1, Jennifer Adelman2, John E. Anderson2, Scott F. Anderson3  +148 moreInstitutions (29)
TL;DR: The Sloan Digital Sky Survey (SDSS) as discussed by the authors provides the data to support detailed investigations of the distribution of luminous and non-luminous matter in the universe: a photometrically and astrometrically calibrated digital imaging survey of π sr above about Galactic latitude 30° in five broad optical bands to a depth of g' ~ 23 mag.
Abstract: The Sloan Digital Sky Survey (SDSS) will provide the data to support detailed investigations of the distribution of luminous and nonluminous matter in the universe: a photometrically and astrometrically calibrated digital imaging survey of π sr above about Galactic latitude 30° in five broad optical bands to a depth of g' ~ 23 mag, and a spectroscopic survey of the approximately 106 brightest galaxies and 105 brightest quasars found in the photometric object catalog produced by the imaging survey. This paper summarizes the observational parameters and data products of the SDSS and serves as an introduction to extensive technical on-line documentation.

9,835 citations


Journal ArticleDOI
TL;DR: Efficient algorithms for the discovery of frequent itemsets which forms the compute intensive phase of the association mining task are presented and the effect of using different database layout schemes combined with the proposed decomposition and traverse techniques are presented.
Abstract: Association rule discovery has emerged as an important problem in knowledge discovery and data mining. The association mining task consists of identifying the frequent itemsets, and then forming conditional implication rules among them. We present efficient algorithms for the discovery of frequent itemsets which forms the compute intensive phase of the task. The algorithms utilize the structural properties of frequent itemsets to facilitate fast discovery. The items are organized into a subset lattice search space, which is decomposed into small independent chunks or sublattices, which can be solved in memory. Efficient lattice traversal techniques are presented which quickly identify all the long frequent itemsets and their subsets if required. We also present the effect of using different database layout schemes combined with the proposed decomposition and traversal techniques. We experimentally compare the new algorithms against the previous approaches, obtaining improvements of more than an order of magnitude for our test databases.

1,637 citations



Journal ArticleDOI
TL;DR: The results of the present study provided the first evidence of enhanced long-term (on the order of days to weeks) functions of osteoblasts cultured on nanophase ceramics, and clearly represent a unique and promising class of orthopaedic/dental implant formulations with improved osseointegrative properties.

1,275 citations


Journal ArticleDOI
TL;DR: Select enhanced osteoblast adhesion was independent of surface chemistry and material phase but was dependent on the surface topography (specifically on grain and pore size) of nanophase ceramics.
Abstract: Osteoblast, fibroblast, and endothelial cell adhesion on nanophase (that is, materials with grain sizes less than 100 nm) alumina, titania, and hydroxyapatite (HA) was investigated using in vitro cellular models. Osteoblast adhesion was significantly (p < 0.01) greater after 4 h on nanophase alumina, titania, and HA than it was on conventional formulations of the same ceramics. In contrast, compared to conventional alumina, titania, and HA, after 4 h fibroblast adhesion was significantly (p < 0.01) less on nanophase ceramics. Examination of the underlying mechanism(s) of cell adhesion on nanophase ceramics revealed that these ceramics adsorbed significantly (p < 0.01) greater quantities of vitronectin, which, subsequently, may have contributed to the observed select enhanced adhesion of osteoblasts. Select enhanced osteoblast adhesion was independent of surface chemistry and material phase but was dependent on the surface topography (specifically on grain and pore size) of nanophase ceramics. The capability of synthesizing and processing nanomaterials with tailored (through, for example, specific grain and pore size) structures and topographies to control select subsequent cell functions provides the possibility of designing the novel proactive biomaterials (that is, materials that elicit specific, timely, and desirable responses from surrounding cells and tissues) necessary for improved implant efficacy.

986 citations


Journal ArticleDOI
TL;DR: It is demonstrated that high-frequency capacitance measurements are most suited to follow the increasing surface coverage of the electrode due to cell spreading, and the excellent time resolution of the ECIS technique allowed an in-depth analysis of cell spreading kinetics under various experimental conditions.

770 citations


Journal ArticleDOI
TL;DR: In this article, a generalized-α method was developed and analyzed for linear, first-order systems and extended to the filtered Navier-Stokes equations within the context of a stabilized finite element method.

735 citations


Journal ArticleDOI
TL;DR: In this paper, a large eddy simulation (LES) formulation is developed from the variational multiscale method, which is confined to the effect of a small-scale Reynolds stress, in contrast with classical LES in which the entire subgrid-scale stress is modeled.
Abstract: A Large Eddy Simulation (LES) formulation is developed from the variational multiscale method. Modeling is confined to the effect of a small-scale Reynolds stress, in contrast with classical LES in which the entire subgrid-scale stress is modeled. All other effects are accounted for exactly. It is argued that many shortcomings of the classical LES/constant-coefficient Smagorinsky model are eliminated by the scale separation inherent ab initio in the present approach.

718 citations


Journal ArticleDOI
TL;DR: An intuitive explanation of SVMs from a geometric perspective is provided and the classification problem is used to investigate the basic concepts behind SVMs and to examine their strengths and weaknesses from a data mining perspective.
Abstract: Support Vector Machines (SVMs) and related kernel methods have become increasingly popular tools for data mining tasks such as classification, regression, and novelty detection. The goal of this tutorial is to provide an intuitive explanation of SVMs from a geometric perspective. The classification problem is used to investigate the basic concepts behind SVMs and to examine their strengths and weaknesses from a data mining perspective. While this overview is not comprehensive, it does provide resources for those interested in further exploring SVMs.

707 citations


Journal ArticleDOI
TL;DR: The work of one theorist, Geert Hofstede, is introduced, and some of his cultural dimensions to Web user interfaces are applied, and how they might affect userinterface designs are considered.
Abstract: This paper introduces dimensions of culture, as analyzed by Geert Hofstede in his classic study of cultures in organizations, and considers how they might affect userinterface designs. Examples from the Web illustrate the cultural dimensions. Introduction The Web enables global distribution of products and services through Internet Websites, intranets, and extranets. Professional analysts and designers generally agree that well-designed user interfaces improve the performance and appeal of the Web, helping to convert \"tourists\" or \"browsers\" to \"residents\" or \"customers.\" The userinterface development process focuses attention on understanding users and acknowledging demographic diversity. But in a global economy, these differences reflect world-wide cultures. What impact might these cultures have on the understanding and use of Web-based communication, content, and tools? This paper contributes to the study of these complex and challenging issues by analyzing some of the needs, wants, preferences, and expectations of different cultures. A few simple questions illustrate the depth of the issues. Consider your favorite Website. How might this Website be understood and used in New York, Paris, London, Beijing, New Delhi, or Tokyo, assuming that adequate verbal translation were accomplished? Might something in its metaphors, mental model, navigation, interaction, or appearance confuse, or even offend and alienate, a user? Consider what year this is. Is it 2000? In some other counting systems, it is 4698, 5760, or 1420. Even to refer to the counting system of another culture might confuse or alienate people used to their own native system. Let us not forget that Hindu-Arabic numerals, which Western society now takes for granted, were once viewed as the work of the devil by Christian Europe, and educated people for hundreds of years blocked their introduction into European society. Whether imports from other cultures are viewed as delightful gifts or poisonous viruses is often a matter of socio-political context. Consider the order in which you prefer to find information. If you are planning a trip by train, do you want to see the schedule information first or read about the organization and assess its credibility. Different cultures look for different data to make decisions. In most projects, Web user-interface and information visualization designers seek to resolve the complex interplay of user, business, marketing, and engineering requirements. Their development process includes iterative steps of planning, research, analysis, design, evaluation, documentation, and training. As they carry out all of these tasks, however, they would do well to consider their own cultural orientation and to understand the preferred structures and processes of other cultures. This attention would help them to achieve more desirable global solutions or to determine to what extent localized, customized designs might be better than international or universal ones. Cultures, even within some countries, are very different. Sacred colors in the Judeo-Christian West (e.g., red, blue, white, gold) are different than Buddhist saffron yellow or Islamic green. Subdued Finnish designs for background screen patterns (see Figure 1) might, or might not be suitable in Mediterranean climates, in Hollywood, USA, or Bollywood, India. These differences go deeper than just appearance; they reflect strong cultural values. How might these cultural differences be understood? Many analysts have studied cultures thoroughly and published classic theories; other authors have applied these theories to analyze the impact of culture on business relations and commerce (see Bibliography). Few of these works are well known to the user-interface design community. This paper introduces the work of one theorist, Geert Hofstede, and applies some of his cultural dimensions to Web user interfaces. Hofstede's Dimensions of Culture During 1978-83, the Dutch cultural anthropologist Geert Hofstede conducted detailed interviews with hundreds of IBM employees in 53 countries. Through standard statistical analysis of fairly large data sets, he was able to determine patterns of similarities and differences among the replies. From this data analysis, he formulated his theory of five fundamental dimensions of all world cultures (although admittedly hissubjects were constrained to one multinational corporation's world-wide employees, and thus to one company culture.). He also maintained that there is a dominant culture for each country. In the 1990s, Hofstede published a more accessible version of his research publication in Cultures and Organizations: Software of the Mind [Hofstede]. His focus was not on the definition of culture as refinement of the mind (or \"highly civilized\" attitudes and behavior) but rather on essential patterns of thinking, feeling, and acting that Hofstede asserted were well-established by late childhood. These cultural differences manifest themselves in a culture's choices of symbols, heroes/heroines, rituals, and values. Hofstede identified five dimensions and rated 53 countries on indices for each dimension, normalized to values (usually) of 0 to 100. His five dimensions of culture are the following: • Power-distance • Collectivism vs. individualism • Femininity vs. masculinity • Uncertainty avoidance • Longvs. short-term orientation Each of Hofstede's terms appears below with an explanation, implications for user-interface and Web design, and illustrations of characteristic Websites. Power Distance Power distance (PD) refers to the extent to which less powerful members expect and accept unequal power distribution within a culture. High PD countries tend to have centralized political power and exhibit tall hierarchies in organizations with large differences in salary and status. Subordinates may view the \"boss\" as a benevolent dictator and are expected to do as they are told. Parents teach obedience, and expect respect. Teachers possess wisdom and are automatically esteemed. Inequalities are expected, and may even be desired. Low PD countries tend to view subordinates and supervisors as closer together and more interchangeable, with flatter hierarchies in organizations and less difference in salaries and status. Parents and children, and teachers and students, may view themselves more as equals (but not necessarily as identical.). Equality is expected and generally desired. Hofstede notes that these differences are hundreds or even thousands of years old and may not disappear quickly from traditional cultures, even with powerful global telecommunication systems. He also notes that there are interesting indicators of power distance: low PD countries tend to have higher geographic latitude, smaller populations, and/or higher gross domestic product (GDP) per capita than high PD countries. Based on this definition, power distance may influence the following aspects of user-interface and Web design: • Access to information: highly (high PD) vs. less-highly (low PD) structured. • Hierarchies in mental models: tall vs. shallow. • Emphasis on social and moral order (e.g., nationalism or religion): significant/frequent vs. minor/infrequent use. • Focus on expertise, authority, experts, official stamps, or logos: strong vs. weak. • Social prominence: leaders vs. citizens, customers, or employees. • Important security, restrictions/barriers to access, use of certificates,: explicit, enforced, frequent restrictions on users vs. transparent, integrated, implicit freedom to roam. • Social roles used to organize information (e.g., a managers’ section obvious to all but sealed off from nonmanagers): frequent vs. infrequent These PD differences can be illustrated on the Web by examining university Web sites from two countries with very different PD indices (Figures 2 and 3). The Universiti Utara Malaysia (www.uum.edu.my) is located in Malaysia, a country with a PD index rating of 104, the highest in Hofstede's analysis. The Website from the Ichthus Hogeschool (www.ichthus-rdam.nl) and the Technische Universiteit Eindhoven (www.tue.nl) are located in the Netherlands, with a PD index rating of 38. Note the differences in the two groups of Websites. The Malaysian Website features strong axial symmetry, a focus on the official seal of the university, photographs of faculty or administration leaders conferring degrees, and monumental buildings in which people play a small role. A top-level menu selection provides a detailed explanation of the symbolism of the official seal and information about the leaders of the university. The Dutch Website features an emphasis on students (not leaders), a stronger use of asymmetric layout, and photos of both genders in illustrations. This Website emphasizes the power of students as consumers and equals. Individualism vs. Collectivism Individualism in cultures implies loose ties; everyone is expected to look after one’s self or immediate family but no one else. Collectivism implies that people are integrated from birth into strong, cohesive groups that protect them in exchange for unquestioning loyalty. At work, individualistic cultures value personal time, freedom, challenge, and such extrinsic motivators as material rewards. In family relations, they value honesty/truth, talking things out, using guilt to achieve behavioral goals, and maintaining self-respect. Their societies and governments place individual socialeconomic interests over the group, maintain strong rights to privacy, nurture strong private opinions (expected from everyone), restrain the power of the state in the economy, emphasize the political power of voters, maintain strong freedom of the press, and profess the ideologies of selfactualization, self-realization, self-government, and freedom. At work, collectivist cultures value training, physical conditions, skills, and the rewards of work itself. In family relations, they value harmony more than honesty/truth, silence,

639 citations


Journal ArticleDOI
TL;DR: A low bit-rate embedded video coding scheme that utilizes a 3-D extension of the set partitioning in hierarchical trees (SPIHT) algorithm which has proved so successful in still image coding, which allows multiresolutional scalability in encoding and decoding in both time and space from one bit stream.
Abstract: We propose a low bit-rate embedded video coding scheme that utilizes a 3-D extension of the set partitioning in hierarchical trees (SPIHT) algorithm which has proved so successful in still image coding. Three-dimensional spatio-temporal orientation trees coupled with powerful SPIHT sorting and refinement renders 3-D SPIHT video coder so efficient that it provides comparable performance to H.263 objectively and subjectively when operated at the bit rates of 30 to 60 kbits/s with minimal system complexity. Extension to color-embedded video coding is accomplished without explicit bit allocation, and can be used for any color plane representation. In addition to being rate scalable, the proposed video coder allows multiresolutional scalability in encoding and decoding in both time and space from one bit stream. This added functionality along with many desirable attributes, such as full embeddedness for progressive transmission, precise rate control for constant bit-rate traffic, and low complexity for possible software-only video applications, makes the proposed video coder an attractive candidate for multimedia applications.

Journal ArticleDOI
TL;DR: The contributions to document image analysis of 99 papers published in the IEEE Transactions on Pattern Analysis and Machine Intelligence (PAMI) are clustered, summarized, interpolated, interpreted, and evaluated.
Abstract: The contributions to document image analysis of 99 papers published in the IEEE Transactions on Pattern Analysis and Machine Intelligence (PAMI) are clustered, summarized, interpolated, interpreted, and evaluated.

Proceedings ArticleDOI
01 Aug 2000
TL;DR: A new framework for associations based on the concept of closed frequent itemsets is presented, with the number of non-redundant rules produced by the new approach is exponentially smaller than the rule set from the traditional approach.
Abstract: The traditional association rule mining framework produces many redundant rules. The extent of redundancy is a lot larger than previously suspected. We present a new framework for associations based on the concept of closed frequent itemsets. The number of non-redundant rules produced by the new approach is exponentially (in the length of the longest frequent itemset) smaller than the rule set from the traditional approach. Experiments using several “hard” as well as “easy” real and synthetic databases confirm the utility of our framework in terms of reduction in the number of rules presented to the user, and in terms of time.

Journal ArticleDOI
TL;DR: A wavelet electrocardiogram (ECG) data codec based on the set partitioning in hierarchical trees (SPIHT) compression algorithm is proposed and is significantly more efficient in compression and in computation than previously proposed ECG compression schemes.
Abstract: A wavelet electrocardiogram (ECG) data codec based on the set partitioning in hierarchical trees (SPIHT) compression algorithm is proposed in this paper. The SPIHT algorithm (A. Said and W.A. Pearlman, IEEE Trans. Ccts. Syst. II, vol. 6, p. 243-50, 1996) has achieved notable success in still image coding. The authors modified the algorithm for the one-dimensional case and applied it to compression of ECG data. Experiments on selected records from the MIT-BIH arrhythmia database revealed that the proposed codec is significantly more efficient in compression and in computation than previously proposed ECG compression schemes. The coder also attains exact bit rate control and generates a bit stream progressive in quality or rate.

Journal ArticleDOI
TL;DR: A review of the current status of intermetallic applications can be found in this article, with emphasis on new uses that are in place or pending, mainly dealing with aluminides and silicides.

Journal ArticleDOI
TL;DR: Density of states calculations of all structures revealed an intrinsic metallic behavior, independent of orientation, tube diameter, and chirality, and it is shown that their mechanical properties are similar to those of graphene.
Abstract: We propose a new family of layered sp(2)-like carbon crystals, incorporating five-, six-, and seven-membered rings in 2D Bravais lattices. These periodic sheets can be rolled so as to generate nanotubes of different diameter and chirality. We demonstrate that these sheets and tubes are metastable and more favorable than C-60, and it is also shown that their mechanical properties are similar to those of graphene. Density of states calculations of all structures revealed an intrinsic metallic behavior, independent of orientation, tube diameter, and chirality.

Journal ArticleDOI
19 May 2000-Science
TL;DR: The coalescence of single-walled nanotubes is studied in situ under electron irradiation at high temperature in a transmission electron microscope, and seems to be restricted to tubes with the same chirality, explaining the low frequency of occurrence of this event.
Abstract: The coalescence of single-walled nanotubes is studied in situ under electron irradiation at high temperature in a transmission electron microscope. The merging process is investigated at the atomic level, using tight-binding molecular dynamics and Monte Carlo simulations. Vacancies induce coalescence via a zipper-like mechanism, imposing a continuous reorganization of atoms on individual tube lattices along adjacent tubes. Other topological defects induce the polymerization of tubes. Coalescence seems to be restricted to tubes with the same chirality, explaining the low frequency of occurrence of this event.

Journal ArticleDOI
TL;DR: In this paper, a complete 2.4¨25 km spectrum of the dust-embedded young stellar object W33A was obtained with the Short Wavelength Spectrometer of the Infrared Space Observatory at a mean resolving power of D750.
Abstract: This paper presents, for the —rst time, a complete 2.4¨25 km spectrum of the dust-embedded young stellar object W33A. The spectrum was obtained with the Short Wavelength Spectrometer of the Infrared Space Observatory at a mean resolving power of D750. The spectrum displays deep ice and silicate H 2 O absorptions centered at 3.0 and 9.7 km, respectively, together with absorption features identi—ed with various other molecules in the solid phase. The 2.4¨5.0 km region of the spectrum is used to investigate the long-standing problem of the ice column density toward W33A, by means of the stretching and H 2 O combination mode features at 3.0 and 4.5 km. Although no —ux is seen at the center of the 3.0 km feature, its central depth may be constrained by —tting assumed pro—les to the short- and long- wavelength wings in our spectrum. We deduce that a value of cm~2 is con- N(H 2 O) \ (1.1 ^ 0.3) ) 1019 sistent with these features, a factor of at least 3 less than predicted by the bending mode at 6.0 km; H 2 O the reason for this discrepancy is unclear. We report new results on the abundances of nitrogen-bearing species in the ices toward W33A. Solid is detected for the —rst time in this line of sight, by means NH 3 of the inversion-mode feature at 9.0 km. The column density is cm~2, N(NH 3 ) \ (1.7 ^ 0.4) ) 1018 implying an abundance of D15% relative to comparable to that recently reported toward the H 2 O, young star NGC 7538 IRS 9. However, we —nd no convincing evidence for absorptions associated with the C"N stretching mode of nitriles in the 4.4¨4.6 km region of the spectrum. If nitriles are present in the ices along this line of sight, they must have column density no more than D1017 cm~2 or D1% relative to This argues against identi—cation of the deep 4.62 km iXCNfeature with isonitriles, as

Journal ArticleDOI
TL;DR: In this article, two amplitude-dependent site amplification factors are specified: Fa for short periods and Fv for longer periods, and the new site classification system is based on definitions of five site classes in terms of a representative average shear wave velocity to a depth of 30 m (V¯s).
Abstract: Recent code provisions for buildings and other structures (1994 and 1997 NEHRP Provisions, 1997 UBC) have adopted new site amplification factors and a new procedure for site classification. Two amplitude‐dependent site amplification factors are specified: Fa for short periods and Fv for longer periods. Previous codes included only a long period factor S and did not provide for a short period amplification factor. The new site classification system is based on definitions of five site classes in terms of a representative average shear wave velocity to a depth of 30 m (V¯s). This definition permits sites to be classified unambiguously. When the shear wave velocity is not available, other soil properties such as standard penetration resistance or undrained shear strength can be used. The new site classes denoted by letters A ‐ E, replace site classes in previous codes denoted by S1 ‐ S4. Site classes A and B correspond to hard rock and rock, Site Class C corresponds to soft rock and very stiff / ver...

Journal ArticleDOI
TL;DR: In this paper, a sample of 4208 objects with magnitude 15 < g* < 22 and colors of main-sequence A stars have been selected from 370 deg2 of Sloan Digital Sky Survey (SDSS) commissioning observations.
Abstract: A sample of 4208 objects with magnitude 15 < g* < 22 and colors of main-sequence A stars have been selected from 370 deg2 of Sloan Digital Sky Survey (SDSS) commissioning observations. The data is from two long, narrow stripes, each with an opening angle of greater than 60°, at Galactic latitudes 36° < |b| < 63° on the celestial equator. Relative photometric calibrations good to 2% and consistent absolute photometry allows this uniform sample to be treated statistically over the large area. An examination of the sample's distribution shows that these stars trace considerable substructure in the halo. Large overdensities of A-colored stars in the north at (l, b, R) = (350°, 50°, 46 kpc) and in the south at (157, -58, 33 kpc) and extending over tens of degrees are present in the halo of the Milky Way. Ivezic et al. have detected the northern structure from a sample of RR Lyrae stars in the SDSS. Using photometry to separate the stars by surface gravity, both structures are shown to contain a sequence of low surface gravity stars consistent with identification as a blue horizontal branch (BHB). Both structures also contain a population of high surface gravity stars 2 mag fainter than the BHB stars, consistent with their identification as blue stragglers (BSs). The majority of the high surface gravity stars in the Galactic halo may be BS stars like these. A population of F stars associated with the A star excess in the southern structure is detected (the F stars in the northern structure at 46 kpc would be too faint for the SDSS to detect). From the numbers of detected BHB stars, lower limits to the implied mass of the structures are 6 × 106 M☉ and 2 × 106 M☉, although one does not yet know the full spatial extent of the structures. The fact that two such large clumps have been detected in a survey of only 1% of the sky indicates that such structures are not uncommon in the halo. Simple spheroidal parameters are fit to a complete sample of the remaining unclumped BHB stars and yield (at r < 40 kpc) a fit to a halo distribution with flattening (c/a = 0.65 ± 0.2) and a density falloff exponent of α = -3.2 ± 0.3.

Journal Article
TL;DR: Research in biomaterials and biomechanics has fueled a large part of the significant revolution associated with osseointegrated implants; however, several important questions still remain, and much of what is done now by clinicians remains empirical.
Abstract: Research in biomaterials and biomechanics has fueled a large part of the significant revolution associated with osseointegrated implants. Additional key areas that may become even more important--such as guided tissue regeneration, growth factors, and tissue engineering--could not be included in this review because of space limitations. All of this work will no doubt continue unabated; indeed, it is probably even accelerating as more clinical applications are found for implant technology and related therapies. An excellent overall summary of oral biology and dental implants recently appeared in a dedicated issue of Advances in Dental Research. Many advances have been made in the understanding of events at the interface between bone and implants and in developing methods for controlling these events. However, several important questions still remain. What is the relationship between tissue structure, matrix composition, and biomechanical properties of the interface? Do surface modifications alter the interfacial tissue structure and composition and the rate at which it forms? If surface modifications change the initial interface structure and composition, are these changes retained? Do surface modifications enhance biomechanical properties of the interface? As current understanding of the bone-implant interface progresses, so will development of proactive implants that can help promote desired outcomes. However, in the midst of the excitement born out of this activity, it is necessary to remember that the needs of the patient must remain paramount. It is also worth noting another as-yet unsatisfied need. With all of the new developments, continuing education of clinicians in the expert use of all of these research advances is needed. For example, in the area of biomechanical treatment planning, there are still no well-accepted biomaterials/biomechanics "building codes" that can be passed on to clinicians. Also, there are no readily available treatment-planning tools that clinicians can use to explore "what-if" scenarios and other design calculations of the sort done in modern engineering. No doubt such approaches could be developed based on materials already in the literature, but unfortunately much of what is done now by clinicians remains empirical. A worthwhile task for the future is to find ways to more effectively deliver products of research into the hands of clinicians.

Proceedings Article
29 Jun 2000
TL;DR: An intuitive geometric interpretation of the standard support vector machine for classification of both linearly separable and inseparable data is developed and a rigorous derivation of the concepts behind the geometry is provided.
Abstract: We develop an intuitive geometric interpretation of the standard support vector machine (SVM) for classification of both linearly separable and inseparable data and provide a rigorous derivation of the concepts behind the geometry. For the separable case finding the maximum margin between the two sets is equivalent to finding the closest points in the smallest convex sets that contain each class (the convex hulls). We now extend this argument to the inseparable case by using a reduced convex hull reduced away from outliers. We prove that solving the reduced convex hull formulation is exactly equivalent to solving the standard inseparable SVM for appropriate choices of parameters. Some additional advantages of the new formulation are that the effect of the choice of parameters becomes geometrically clear and that the formulation may be solved by fast nearest point algorithms. By changing norms these arguments hold for both the standard 2-norm and 1-norm SVM.

Journal ArticleDOI
TL;DR: Interactions involving a polar Asn side chain provide a strong thermodynamic driving force for membrane helix association within a membrane-like environment.
Abstract: In membrane proteins, the extent to which polarity, hydrogen bonding, and van der Waals packing interactions of the buried, internal residues direct protein folding and association of transmembrane segments is poorly understood The energetics associated with these various interactions should differ substantially between membrane versus water-soluble proteins To help evaluate these energetics, we have altered a water-soluble, two-stranded coiled-coil peptide to render its sequence soluble in membranes The membrane-soluble peptide associates in a monomer-dimer-trimer equilibrium, in which the trimer predominates at the highest peptide/detergent ratios The oligomers are stabilized by a buried Asn side chain Mutation of this Asn to Val essentially eliminates oligomerization of the membrane-soluble peptide Thus, within a membrane-like environment, interactions involving a polar Asn side chain provide a strong thermodynamic driving force for membrane helix association

Journal ArticleDOI
TL;DR: Detailed information is provided about how to construct an image-based whole-body model, called VIP-Man, as well as how to adopt it into well-tested Monte Carlo codes, EGS4, MCNP4B, and MCNPX.
Abstract: Human anatomical models have been indispensable to radiation protection dosimetry using Monte Carlo calculations. Existing MIRD-based mathematical models are easy to compute and standardize, but they are simplified and crude compared to human anatomy. This article describes the development of an image-based whole-body model, called VIP-Man, using transversal color photographic images obtained from the National Library of Medicine's Visible Human Project for Monte Carlo organ dose calculations involving photons, electron, neutrons, and protons. As the first of a series of papers on dose calculations based on VIP-Man, this article provides detailed information about how to construct an image-based model, as well as how to adopt it into well-tested Monte Carlo codes, EGS4, MCNP4B, and MCNPX.

Journal ArticleDOI
TL;DR: In this article, Hidden Markov Models (HMMs) are used to organize observed activity into meaningful states by minimizing the entropy of the joint distribution of the HMMs' internal state machine.
Abstract: Hidden Markov models (HMMs) have become the workhorses of the monitoring and event recognition literature because they bring to time-series analysis the utility of density estimation and the convenience of dynamic time warping. Once trained, the internals of these models are considered opaque; there is no effort to interpret the hidden states. We show that by minimizing the entropy of the joint distribution, an HMM's internal state machine can be made to organize observed activity into meaningful states. This has uses in video monitoring and annotation, low bit-rate coding of scene activity, and detection of anomalous behavior. We demonstrate with models of office activity and outdoor traffic, showing how the framework learns principal modes of activity and patterns of activity change. We then show how this framework can be adapted to infer hidden state from extremely ambiguous images, in particular, inferring 3D body orientation and pose from sequences of low-resolution silhouettes.

01 May 2000
TL;DR: Preliminary numerical tests on real datasets indicate the constrained approach is less prone to poor local solutions, producing a better summary of the underlying data.
Abstract: We consider practical methods for adding constraints to the K-Means clustering algorithm in order to avoid local solutions with empty clusters or clusters having very few points. We often observe this phenomena when applying K-Means to datasets where the number of dimensions is n 10 and the number of desired clusters is k 20. We propose explicitly adding k constraints to the underlying clustering optimization problem requiring that each cluster have at least a minimum number of points in it. We then investigate the resulting cluster assignment step. Preliminary numerical tests on real datasets indicate the constrained approach is less prone to poor local solutions, producing a better summary of the underlying data. Contrained K-Means Clustering 1

Journal ArticleDOI
01 Dec 2000-Geology
TL;DR: In this paper, two natural amphibolite facies metapelites from the central Himalaya of Nepal exhibit extremely common compositional patterns, including increases in Mn and Fe/(Fe + Mg) at the rims of garnets, which are the result of retrograde garnet dissolution and Fe-Mg exchange with biotite.
Abstract: Retrograde net transfer reactions significantly affect compositions of metamorphic minerals, yet are rarely considered when determining pressure-temperature (P-T) conditions. Two natural amphibolite facies metapelites from the central Himalaya of Nepal exhibit extremely common compositional patterns, including increases in Mn and Fe/(Fe + Mg) at the rims of garnets, which are the result of retrograde garnet dissolution and Fe-Mg exchange with biotite. However, typical thermobarometric approaches for these rocks result in errors of hundreds of degrees and 3–6 kbar compared with thermobarometry of nearby rocks and petrogenetic grids. These large errors result because dissolution of high-Fe garnet has strongly affected the Fe/Mg ratio of matrix biotite. X-ray maps help evaluate the extent and chemical effects of retrograde reactions in these samples by identifying mineral regions that retain highest-T compositions, or, through a new data-processing approach, by permitting correction of mineral compositions to original high-T values. These approaches ensure against retrograde net transfer reactions and should be applied routinely in thermobarometric studies—they ultimately yield P-T estimates that are more petrologically reasonable, and permit rapid screening of samples for those least affected by retrograde reactions. Reconsideration of thermobarometry in the central and eastern Himalaya indicates that retrograde net transfer reactions are extremely common. Therefore, previous thermobarometric studies based on garnet major element compositions from that region should be reevaluated.

Journal ArticleDOI
TL;DR: A hidden Markov model for general protein sequence based on the I-sites library of sequence-structure motifs, HMMSTR, which attributes a considerably higher probability to coding sequence than does an equivalent dipeptide model, predicts secondary structure better than any previously reported method and the structural context of beta strands and turns with an accuracy that should be useful for tertiary structure prediction.

Journal ArticleDOI
TL;DR: In this article, the authors report on modeling of direct current (DC) characteristics of organic pentacene thin film transistors of different designs, incorporating a gatevoltage dependent mobility and highly nonlinear drain and source contact series resistances.
Abstract: We report on modeling of direct current (DC) characteristics of organic pentacene thin film transistors of different designs. Our model incorporates a gate-voltage dependent mobility and highly nonlinear drain and source contact series resistances. The contact nonlinearities are especially pronounced in bottom source and drain contact thin film transistors. The model successfully reproduced both below- and above-threshold characteristics of top source and drain contact and bottom source and drain contact organic pentacene thin film transistors.

Journal ArticleDOI
TL;DR: The authors found that successful entrepreneurs appear to have higher social competence, i.e., the ability to interact effectively with others, and are better at social perception and adapting to new social situations.
Abstract: Why are some entrepreneurs so much more successful than others in starting new companies—ones that create wealth for their societies as well as themselves? Growing evidence suggests that the answer involves the influence of both cognitive and social factors. Successful entrepreneurs appear to think differently than other persons in several respects (e.g., they are less likely to engage in counterfactual thinking but more likely to show overconfidence in their judgments). Similarly, successful entrepreneurs appear to be higher in social competence—the ability to interact effectively with others (e.g., they are better at social perception and adapting to new social situations). These results suggest that the principles and findings of psychology can be invaluable to researchers in the field of entrepreneurship, providing important insights into the factors that influence entrepreneurs' success.