1,119 research outputs found
Assessing the Effectiveness and Usability of Personalized Internet Search through a Longitudinal Evaluation
This paper discusses a longitudinal user evaluation of Prospector, a personalized Internet meta-search engine capable of personalized re-ranking of search results. Twenty-one participants used Prospector as their primary search engine for 12 days, agreed to have their interaction with the system logged, and completed three questionnaires. The data logs show that the personalization provided by Prospector is successful: participants preferred re-ranked results that appeared higher up. However, the questionnaire results indicated that people would prefer to use Google instead (their search engine of choice). Users would, nevertheless, consider employing a personalized search engine to perform searches with terms that require disambiguation and/or contextualization. We conclude the paper with a discussion on the merit of combining system- and user-centered evaluation for the case of personalized systems
Transport through anisotropic magnetic molecules with partially ferromagnetic leads: Spin-charge conversion and negative differential conductance
We theoretically investigate inelastic transport through anisotropic magnetic
molecules weakly coupled to one ferromagnetic and one nonmagnetic lead. We find
that the current is suppressed over wide voltage ranges due to spin blockade.
In this system, spin blockade is associated with successive spin flips of the
molecular spins and depends on the anisotropy energy barrier. This leads to the
appearance of a window of bias voltages between the Coulomb blockade and spin
blockade regimes where the current is large and to negative differential
conductance at low temperatures. Remarkably, negative differential conductance
is also present close to room temperature. Spin-blockade behavior is
accompanied by super-Poissonian shot noise, like in nonmagnetic quantum dots.
Finally, we show that the charge transmitted through the molecule between
initial preparation in a certain spin state and infinite time very strongly
depends on the initial spin state in certain parameter ranges. Thus the
molecule can act as a spin-charge converter, an effect potentially useful as a
read-out mechanism for molecular spintronics.Comment: 8 pages with 5 figures, version as publishe
Surface energy and boundary layers for a chain of atoms at low temperature
We analyze the surface energy and boundary layers for a chain of atoms at low
temperature for an interaction potential of Lennard-Jones type. The pressure
(stress) is assumed small but positive and bounded away from zero, while the
temperature goes to zero. Our main results are: (1) As at fixed positive pressure , the Gibbs measures and
for infinite chains and semi-infinite chains satisfy path large
deviations principles. The rate functions are bulk and surface energy
functionals and
. The minimizer of the surface functional
corresponds to zero temperature boundary layers. (2) The surface correction to
the Gibbs free energy converges to the zero temperature surface energy,
characterized with the help of the minimum of
. (3) The bulk Gibbs measure and Gibbs
free energy can be approximated by their Gaussian counterparts. (4) Bounds on
the decay of correlations are provided, some of them uniform in
Using thematic ontologies for user- and group- based adaptive personalization in web searching
This paper presents Prospector, an adaptive meta-search layer, which performs personalized re-ordering of search results. Prospector combines elements from two approaches to adaptive search support: (a) collaborative web searching; and, (b) personalized searching using semantic metadata. The paper focuses on the way semantic metadata and the users’ search behavior are utilized for user- and group- modeling, as well as on how these models are used to re-rank results returned for individual queries. The paper also outlines past evaluation activities related to Prospector, and discusses potential applications of the approach for the adaptive retrieval of multimedia documents
Social risk effects: the 'experience of social risk' factor
Anticipating "social risk", or risk caused by humans, affects decision-making differently from anticipating natural risk. Drawing upon a large sample of the US population (n=3,982), we show that the phenomenon generalizes to risk experience. Experiencing adverse outcomes caused by another human reduces future risk-taking, but experiencing the same outcome caused by nature does not. While puzzling from a consequentialist perspective, the Experience of Social Risk Factor that we identify deepens our understanding of decision-making in settings in which outcomes are co-determined by different sources of uncertainty. Our findings imply that a unifying theory of social risk effects requires new explanations
Distribution of cracks in a chain of atoms at low temperature
We consider a one-dimensional classical many-body system with interaction potential of Lennard--Jones type in the thermodynamic limit at low temperature 1/β ∈ (0, ∞). The ground state is a periodic lattice. We show that when the density is strictly smaller than the density of the ground state lattice, the system with N particles fills space by alternating approximately crystalline domains (clusters) with empty domains (voids) due to cracked bonds. The number of domains is of the order of N exp(-β e surf /2) with e surf > 0 a surface energy
Pharmacokinetics of Caffeine: A Systematic Analysis of Reported Data for Application in Metabolic Phenotyping and Liver Function Testing
Caffeine is by far the most ubiquitous psychostimulant worldwide found in tea, coffee, cocoa, energy drinks, and many other beverages and food. Caffeine is almost exclusively metabolized in the liver by the cytochrome P-450 enzyme system to the main product paraxanthine and the additional products theobromine and theophylline. Besides its stimulating properties, two important applications of caffeine are metabolic phenotyping of cytochrome P450 1A2 (CYP1A2) and liver function testing. An open challenge in this context is to identify underlying causes of the large inter-individual variability in caffeine pharmacokinetics. Data is urgently needed to understand and quantify confounding factors such as lifestyle (e.g., smoking), the effects of drug-caffeine interactions (e.g., medication metabolized via CYP1A2), and the effect of disease. Here we report the first integrative and systematic analysis of data on caffeine pharmacokinetics from 141 publications and provide a comprehensive high-quality data set on the pharmacokinetics of caffeine, caffeine metabolites, and their metabolic ratios in human adults. The data set is enriched by meta-data on the characteristics of studied patient cohorts and subjects (e.g., age, body weight, smoking status, health status), the applied interventions (e.g., dosing, substance, route of application), measured pharmacokinetic time-courses, and pharmacokinetic parameters (e.g., clearance, half-life, area under the curve). We demonstrate via multiple applications how the data set can be used to solidify existing knowledge and gain new insights relevant for metabolic phenotyping and liver function testing based on caffeine. Specifically, we analyzed 1) the alteration of caffeine pharmacokinetics with smoking and use of oral contraceptives; 2) drug-drug interactions with caffeine as possible confounding factors of caffeine pharmacokinetics or source of adverse effects; 3) alteration of caffeine pharmacokinetics in disease; and 4) the applicability of caffeine as a salivary test substance by comparison of plasma and saliva data. In conclusion, our data set and analyses provide important resources which could enable more accurate caffeine-based metabolic phenotyping and liver function testing.Peer Reviewe
Measurements of Streams Agitated by Fluid Loaded SAW-devices Using a Volumetric 3-component Measurement Technique (V3V)
Utilizing surface acoustic waves (SAW) to induce tailored fluid motion via the acoustic streaming requires detailed knowledge about the acoustic bulk wave excitation. For the first time, the Defocus Digital Particle Image Velocimetry is used to measure the fluid motion originating from a fluid loaded SAW-device. With this flow measurement technique, the acoustic streaming-induced fluid motion can be observed volumetrically, which is attractive not only for application, but also for simulation in order to gain deeper insights regarding three-dimensional acoustic effects
p-Adic Lifting Problems and Derived Equivalences
For two derived equivalent -algebras and , we
introduce a correspondence between \OO-orders reducing to and
\OO-orders reducing to . We outline how this may be used to
transfer properties like uniqueness (or non-existence) of a lift between
and . As an application, we look at tame algebras of
dihedral type with two simple modules, where, most notably, we are able to show
that among those algebras only the algebras and
can actually occur as basic algebras of blocks of
group rings of finite groups
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