132,274 research outputs found
Existence and Warr Neutrality for Matching Equilibria in a Public Good Economy: An Aggregative Game Approach
No full textUsing the aggregative game approach as developed by Cornes and Hartley (2003, 2007) this paper analyzes the conditions under which matching mechanisms in a public good economy lead to interior matching equilibria in which all agents make strictly positive flat contributions to the public good. In particular we show that the distribution of income among the agents is a crucial determinant for the existence of interior matching equilibria. In addition, we explore which matching mechanisms show Warr neutrality and how the size of the economy affects the possibility of implementing a certain type of Pareto optimal solutions through matching.
A fundamental limit on the performance of geometrically-tuned planar resonators
No full textGeometric frequency tuning in planar electromagnetic resonators is common in many applications. It comes, however, at a penalty in the resonance quality, Q0. The literature traces the causes of such penalty often in terms of the shortcomings in the added elements and materials, which were used to achieve the tuning. In this paper, however, it is shown that another underlying source of quality degradation exists at the fundamental geometric level. This source, unlike other added sources of degradation during tuning, will always exist (even before tuning takes place) and will rely on the “modal areas” of the geometric modifications made to host the tuning mechanism. Hence, it forms an upper bound to the performance that can be achieved from a geometically-tuned planar resonator, carries an important insight to resonator design in general, and significantly helps in the understanding of the problem of geometric tuning in particular. We present the electromagnetic theory behind this limit and canonically demonstrate it using practical microwave resonator examples. The theory, finite-element method simulation, and experiment results are presented and good agreement is observed. It is shown that incorporating such understanding into the design process of tunable planar resonators can help optimize their performance against a given set of design requirements. Furthermore, the presented theory provides a useful electromagnetic model as a tool for estimating Q0 for geometrically modified or irregular metal patches and planar resonators in general, to assist analysis, and design at any wavelength or application. The theory also asserts that, under a given mode, a planar resonator will always have its maximum Q0 before introducing any internal subtractive geometric modifications (e.g., cuts, apertures, or slits) to its original shape.Geometric frequency tuning in planar electromagnetic resonators is common in many applications. It comes, however, at a penalty in the resonance quality, Q0. The literature traces the causes of such penalty often in terms of the shortcomings in the added elements and materials, which were used to achieve the tuning. In this paper, however, it is shown that another underlying source of quality degradation exists at the fundamental geometric level. This source, unlike other added sources of degradation during tuning, will always exist (even before tuning takes place) and will rely on the “modal areas” of the geometric modifications made to host the tuning mechanism. Hence, it forms an upper bound to the performance that can be achieved from a geometically-tuned planar resonator, carries an important insight to resonator design in general, and significantly helps in the understanding of the problem of geometric tuning in particular. We present the electromagnetic theory behind this limit and canonically demonstrate it using practical microwave resonator examples. The theory, finite-element method simulation, and experiment results are presented and good agreement is observed. It is shown that incorporating such understanding into the design process of tunable planar resonators can help optimize their performance against a given set of design requirements. Furthermore, the presented theory provides a useful electromagnetic model as a tool for estimating Q0 for geometrically modified or irregular metal patches and planar resonators in general, to assist analysis, and design at any wavelength or application. The theory also asserts that, under a given mode, a planar resonator will always have its maximum Q0 before introducing any internal subtractive geometric modifications (e.g., cuts, apertures, or slits) to its original shape
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Choir with piano
No full textThis photo shows a choir standing on the auditorium stage in four tiered rows. Twenty males and 38 females wear black choral robes with pants, white shirts and dark neckties for the males, and white robin hood collars, white shirts and skirts or dresses for the females. Standing to the left of the ensemble are two males dressed in dark suits with white shirts and black bow ties and two females dressed in white prom-style, off-the-shoulder dresses. Standing to the right of the ensemble are two more females in similar dress. Behind them sits a baby grand piano. Curtains hang in the back of the ensemble. A velvet-looking valence hangs above the stage, with a decorated main valence. The valence has the letter "D" within a laurel wreath that has a bow. Satin trims the valence
Choir with piano
No full textThis photo shows a choir standing on the auditorium stage in four tiered rows. Twenty males and 38 females wear black choral robes with pants, white shirts and dark neckties for the males, and white robin hood collars, white shirts and skirts or dresses for the females. Standing to the left of the ensemble are two males dressed in dark suits with white shirts and black bow ties and two females dressed in white prom-style, off-the-shoulder dresses. Standing to the right of the ensemble are two more females in similar dress. Behind them sits a baby grand piano. Curtains hang in the back of the ensemble. A velvet-looking valence hangs above the stage, with a decorated main valence. The valence has the letter "D" within a laurel wreath that has a bow. Satin trims the valence
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Choir with violinist
No full textThis photo appears to be of a school choir, taken on stage, possibly before a performance. It is unclear what school the location of this photo is. The backstage curtain hangs behind the choir. A man holding a violin stands photo-left next to a woman who appears to be the choral conductor. Approximately 90 students stand on tiered platforms, hands clasped in front for females and placed in back for males, wearing white long-sleeved shirts with dark ties, pants for males, and calf-length skirts for females; all wear dark shoes. Twenty-seven young men are standing in the center of the ensemble. The young ladies stand in groups on either side of them. Three young men in dark suits, white shirts, and dark ties stand to the group's right. Framing the stage is a dark velvet-looking curtain with a decorated main valence. The valence has the letter "D" within a laurel wreath with a bow. Satin trims the valence. The United States flag is on the stage's left side, and the state flag is on the right
Choir with violinist
No full textThis photo appears to be of a school choir, taken on stage, possibly before a performance. It is unclear what school the location of this photo is. The backstage curtain hangs behind the choir. A man holding a violin stands photo-left next to a woman who appears to be the choral conductor. Approximately 90 students stand on tiered platforms, hands clasped in front for females and placed in back for males, wearing white long-sleeved shirts with dark ties, pants for males, and calf-length skirts for females; all wear dark shoes. Twenty-seven young men are standing in the center of the ensemble. The young ladies stand in groups on either side of them. Three young men in dark suits, white shirts, and dark ties stand to the group's right. Framing the stage is a dark velvet-looking curtain with a decorated main valence. The valence has the letter "D" within a laurel wreath with a bow. Satin trims the valence. The United States flag is on the stage's left side, and the state flag is on the right
Wide tuning-range planar filters using lumped-distributed coupled resonators
No full textThis paper describes a discretely tunable filter topology based on lumped-distributed coupled transmission lines, particularly suitable for microelectromechanical systems switching devices. This topology is capable of simultaneous wide-band center frequency and bandwidth tuning, limited only by the electrical size of the transmission lines and the placement density of the switching devices. Low fractional bandwidths can be achieved without the need for large coupled-line spacings due to the antiphase relationship of the lumped capacitive and distributed electromagnetic coupling coefficients. The positions of the additional poles of attenuation due to the lumped capacitive coupling can be selected either above or below band leading to the choice of a narrow bandwidth design having good high-side performance or a design with compromised upper stopband performance, but with no bandwidth tuning limitations. The interaction between a pair of lumped-distributed coupled transmission lines is analyzed and the resulting model is used to develop a filter synthesis procedure. The synthesis procedure and filter performance are validated through theoretical and experimental comparisons using a filter with low-side attenuation poles.This paper describes a discretely tunable filter topology based on lumped-distributed coupled transmission lines, particularly suitable for microelectromechanical systems switching devices. This topology is capable of simultaneous wide-band center frequency and bandwidth tuning, limited only by the electrical size of the transmission lines and the placement density of the switching devices. Low fractional bandwidths can be achieved without the need for large coupled-line spacings due to the antiphase relationship of the lumped capacitive and distributed electromagnetic coupling coefficients. The positions of the additional poles of attenuation due to the lumped capacitive coupling can be selected either above or below band leading to the choice of a narrow bandwidth design having good high-side performance or a design with compromised upper stopband performance, but with no bandwidth tuning limitations. The interaction between a pair of lumped-distributed coupled transmission lines is analyzed and the resulting model is used to develop a filter synthesis procedure. The synthesis procedure and filter performance are validated through theoretical and experimental comparisons using a filter with low-side attenuation poles
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