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Institution

Villanova University

EducationRadnor, Pennsylvania, United States
About: Villanova University is a education organization based out in Radnor, Pennsylvania, United States. It is known for research contribution in the topics: Population & White dwarf. The organization has 5761 authors who have published 12832 publications receiving 300480 citations. The organization is also known as: Villanova.


Papers
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Journal ArticleDOI
TL;DR: Gaia as discussed by the authors is a cornerstone mission in the science programme of the European Space Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach.
Abstract: Gaia is a cornerstone mission in the science programme of the EuropeanSpace Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach. Both the spacecraft and the payload were built by European industry. The involvement of the scientific community focusses on data processing for which the international Gaia Data Processing and Analysis Consortium (DPAC) was selected in 2007. Gaia was launched on 19 December 2013 and arrived at its operating point, the second Lagrange point of the Sun-Earth-Moon system, a few weeks later. The commissioning of the spacecraft and payload was completed on 19 July 2014. The nominal five-year mission started with four weeks of special, ecliptic-pole scanning and subsequently transferred into full-sky scanning mode. We recall the scientific goals of Gaia and give a description of the as-built spacecraft that is currently (mid-2016) being operated to achieve these goals. We pay special attention to the payload module, the performance of which is closely related to the scientific performance of the mission. We provide a summary of the commissioning activities and findings, followed by a description of the routine operational mode. We summarise scientific performance estimates on the basis of in-orbit operations. Several intermediate Gaia data releases are planned and the data can be retrieved from the Gaia Archive, which is available through the Gaia home page.

5,164 citations

Journal ArticleDOI
19 Feb 2010-Science
TL;DR: The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars, which is the region where planetary temperatures are suitable for water to exist on a planet's surface.
Abstract: The Kepler mission was designed to determine the frequency of Earth-sized planets in and near the habitable zone of Sun-like stars. The habitable zone is the region where planetary temperatures are suitable for water to exist on a planet’s surface. During the first 6 weeks of observations, Kepler monitored 156,000 stars, and five new exoplanets with sizes between 0.37 and 1.6 Jupiter radii and orbital periods from 3.2 to 4.9 days were discovered. The density of the Neptune-sized Kepler-4b is similar to that of Neptune and GJ 436b, even though the irradiation level is 800,000 times higher. Kepler-7b is one of the lowest-density planets (~0.17 gram per cubic centimeter) yet detected. Kepler-5b, -6b, and -8b confirm the existence of planets with densities lower than those predicted for gas giant planets.

3,663 citations

Journal ArticleDOI
TL;DR: In this article, the main general features of extinction from the IR through the UV are reviewed, along with the nature of observed spatial variations, and several strategies for dereddening are discussed along with estimates of the uncertainties inherent in each method.
Abstract: This paper addresses the issue of how best to correct astronomical data for the wavelength‐dependent effects of Galactic interstellar extinction. The main general features of extinction from the IR through the UV are reviewed, along with the nature of observed spatial variations. The enormous range of extinction properties found in the Galaxy, particularly in the UV spectral region, is illustrated. Fortunately, there are some tight constraints on the wavelength dependence of extinction and some general correlations between extinction curve shape and interstellar environment. These relationships provide some guidance for correcting data for the effects of extinction. Several strategies for dereddening are discussed along with estimates of the uncertainties inherent in each method. In the Appendix, a new derivation of the wavelength dependence of an average Galactic extinction curve from the IR through the UV is presented, along with a new estimate of how this extinction law varies with the paramet...

2,867 citations

Journal ArticleDOI
TL;DR: In this article, the authors describe the results of a critical incident study based on more than 800 incidents involving self-service technologies solicited from customers through a Web-based survey, and present a discussion of the resulting critical incident categories and their relationship to customer attributions, complaining behavior, word of mouth, and repeat purchase intentions.
Abstract: Self-service technologies (SSTs) are increasingly changing the way customers interact with firms to create service outcomes. Given that the emphasis in the academic literature has focused almost exclusively on the interpersonal dynamics of service encounters, there is much to be learned about customer interactions with technology-based self-service delivery options. In this research, the authors describe the results of a critical incident study based on more than 800 incidents involving SSTs solicited from customers through a Web-based survey. The authors categorize these incidents to discern the sources of satisfaction and dissatisfaction with SSTs. The authors present a discussion of the resulting critical incident categories and their relationship to customer attributions, complaining behavior, word of mouth, and repeat purchase intentions, which is followed by implications for managers and researchers.

2,721 citations

Journal ArticleDOI
TL;DR: A new source separation technique exploiting the time coherence of the source signals is introduced, which relies only on stationary second-order statistics that are based on a joint diagonalization of a set of covariance matrices.
Abstract: Separation of sources consists of recovering a set of signals of which only instantaneous linear mixtures are observed. In many situations, no a priori information on the mixing matrix is available: The linear mixture should be "blindly" processed. This typically occurs in narrowband array processing applications when the array manifold is unknown or distorted. This paper introduces a new source separation technique exploiting the time coherence of the source signals. In contrast with other previously reported techniques, the proposed approach relies only on stationary second-order statistics that are based on a joint diagonalization of a set of covariance matrices. Asymptotic performance analysis of this method is carried out; some numerical simulations are provided to illustrate the effectiveness of the proposed method.

2,721 citations


Authors

Showing all 5830 results

NameH-indexPapersCitations
Jonathan S. Weissman13235791528
Charles Taylor12674177626
H. Vincent Poor109211667723
Thomas W. Smith9873537246
Linda H. Aiken9534143732
S. Joseph Wright8927425996
Jackie Y. Ying8958735694
Elaine Larson8867431100
David L. Penn8432827495
Ignasi Ribas8254723785
David G. Nathan7937921794
Matthew Hall7582724352
Arnold L. Rheingold7476824947
Christopher Williams7359054807
Moeness G. Amin7080119332
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202339
202292
2021737
2020718
2019642
2018573