Search results for "EXPANSION"
showing 10 items of 630 documents
Cascading dust inflation in Born-Infeld gravity
2015
In the framework of Born-Infeld inspired gravity theories, which deviates from General Relativity (GR) in the high curvature regime, we discuss the viability of Cosmic Inflation without scalar fields. For energy densities higher than the new mass scale of the theory, a gravitating dust component is shown to generically induce an accelerated expansion of the Universe. Within such a simple scenario, inflation gracefully exits when the GR regime is recovered, but the Universe would remain matter dominated. In order to implement a reheating era after inflation, we then consider inflation to be driven by a mixture of unstable dust species decaying into radiation. Because the speed of sound gravi…
Behavior-based personalization in web search
2016
Personalized search approaches tailor search results to users' current interests, so as to help improve the likelihood of a user finding relevant documents for their query. Previous work on personalized search focuses on using the content of the user's query and of the documents clicked to model the user's preference. In this paper we focus on a different type of signal: We investigate the use of behavioral information for the purpose of search personalization. That is, we consider clicks and dwell time for reranking an initially retrieved list of documents. In particular, we (i) investigate the impact of distributions of users and queries on document reranking; (ii) estimate the relevance …
The visual query language CQL for transitive and relational computation
2000
Abstract Classification query language (CQL) is a high-level visual query language with a great expressive power. In CQL the processing of ordinary relations and classifications based on transitive relationships is integrated seamlessly. Relations and classifications are represented in the visual interface in a uniform way through relation and classification skeletons. All query formulation in CQL is QBE-like – based on the intuitive way of filling constants and sample values into the skeletons. In order to guarantee great expressive power, relational and classification expressions can be nested freely with each other at unlimited nesting levels. Recursive definition of transitive processin…
Kristallstruktur, thermische Ausdehnung und Farbwechsel von (Me3Ge)2Sb-Sb(GeMe3)2 und anderen Distibanen
1989
Abstract Single crystals of the distibanes (Me3M)4Sb2 (1: M = Si, 2: M = Ge) are obtained by the oxidation in air of (Me3M)3Sb. The crystal structure of 2 is reported. 2 forms linear chains of distibane molecules in trans conformation with Sb ··· Sb contacts of 386 pm at −110°C and 390 pm at 22°C. The thermal expansion of crystals of 2 and (Me3Sn)4Sb2 (3) has been determined. UV-VIS spectra of 1–3, Me4Sb2 (4), Et4Sb2 (5), and Ph4Sb2 (6) in different phases have been recorded. The spectra of 1–5 are consistent with the visible colour changes.
Strongly decelerated expansion of SN 1979C
2002
We observed SN1979C in M100 on 4 June 1999, about twenty years after explosion, with a very sensitive four-antenna VLBI array at the wavelength of 18cm. The distance to M100 and the expansion velocities are such that the supernova cannot be fully resolved by our Earth-wide array. Model-dependent sizes for the source have been determined and compared with previous results. We conclude that the supernova shock was initially in free expansion for 6 +/- 2 yrs and then experienced a very strong deceleration. The onset of deceleration took place a few years before the abrupt trend change in the integrated radio flux density curves. We estimate the shocked swept-up mass to be about 1.6 solar masse…
Anomalous and Not-So-Common Behavior in Common Ionic Liquids and Ionic Liquid-Containing Systems
2019
This work highlights unexpected, not so well known responses of ionic liquids and ionic liquid-containing systems, which are reported in a collective manner, as a short review. Examples include: (i) Minima in the temperature dependence of the isobaric thermal expansion coefficient of some ILs; (ii) Viscosity Minima in binary mixtures of IL + Molecular solvents; (iii) Anomalies in the surface tension within a family of ILs; (iv) The constancy among IL substitution of Cp/Vm at and around room temperature; (v) ILs as glass forming liquids; (vi) Alternate odd-even side alkyl chain length effects; (vii) Absolute negative pressures in ILs and IL-containing systems; (viii) Reversed-charged ionic l…
Searches for small-scale anisotropies from neutrino point sources with three years of IceCube data
2015
Recently, IceCube found evidence for a diffuse signal of astrophysical neutrinos in an energy range of $60\,\mathrm{TeV}$ to the $\mathrm{PeV}$-scale. The origin of those events, being a key to understanding the origin of cosmic rays, is still an unsolved question. So far, analyses have not succeeded to resolve the diffuse signal into point-like sources. Searches including a maximum-likelihood-ratio test, based on the reconstructed directions and energies of the detected down- and up-going neutrino candidates, were also performed on IceCube data leading to the exclusion of bright point sources. In this paper, we present two methods to search for faint neutrino point sources in three years o…
R2D2 at GeoCLEF 2006: A Combined Approach
2007
This paper describes the participation of a combined approach in GeoCLEF-2006. We have participated in Monolingual English Task and we present joint work of the three groups or teams belonging to the project R2D2 with a new system, combining the three individual systems of these teams. We consider that research in the area of GIR is still in its very early stages, therefore, although a voting system could improve the individual results of each system, we have to further investigate different ways to achieve a better combination of these systems.
Prussian Blue Analogues of Reduced Dimensionality
2012
Abstract: Mixed-valence polycyanides (Prussian Blue analogues) possess a rich palette of properties spanning from room-temperature ferromagnetism to zero thermal expansion, which can be tuned by chemical modifications or the application of external stimuli (temperature, pressure, light irradiation). While molecule-based materials can combine physical and chemical properties associated with molecular-scale building blocks, their successful integration into real devices depends primarily on higher-order properties such as crystal size, shape, morphology, and organization. Herein a study of a new reduced-dimensionality system based on Prussian Blue analogues (PBAs) is presented. The system is …
A Simple Solution for Improving the Effectiveness of Traditional Information Retrieval Systems
2005
In this paper we present a system based on the LSA paradigm to improve the performance of a traditional information retrieval system. The proposed system aims to improve both the recall and the precision capabilities of traditional search engines thanks to a semantic query expansion and a subsequent semantic results filtering. A collection of 650 documents has been used to compare the performances of the proposed system with a traditional search engine. Experimental trials show the effectiveness of the proposed solution