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Institution

University of Patras

EducationPátrai, Greece
About: University of Patras is a education organization based out in Pátrai, Greece. It is known for research contribution in the topics: Population & Catalysis. The organization has 13372 authors who have published 31263 publications receiving 677159 citations. The organization is also known as: Panepistímio Patrón.


Papers
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01 Jan 2002
TL;DR: In this paper, the authors consider selfish routing over a network consisting of m parallel bottleneck links through which $n$ selfish users route their traffic trying to minimize their own expected latency.
Abstract: We consider selfish routing over a network consisting of m parallel links through which $n$ selfish users route their traffic trying to minimize their own expected latency. We study the class of mixed strategies in which the expected latency through each link is at most a constant multiple of the optimum maximum latency had global regulation been available. For the case of uniform links it is known that all Nash equilibria belong to this class of strategies. We are interested in bounding the coordination ratio (or price of anarchy) of these strategies defined as the worst-case ratio of the maximum (over all links) expected latency over the optimum maximum latency. The load balancing aspect of the problem immediately implies a lower bound Ω(ln m ln ln m) of the coordination ratio. We give a tight (up to a multiplicative constant) upper bound. To show the upper bound, we analyze a variant of the classical balls and bins problem, in which balls with arbitrary weights are placed into bins according to arbitrary probability distributions. At the heart of our approach is a new probabilistic tool that we call ball fusion; this tool is used to reduce the variant of the problem where balls bear weights to the classical version (with no weights). Ball fusion applies to more general settings such as links with arbitrary capacities and other latency functions.

123 citations

Journal ArticleDOI
TL;DR: In this paper, the ability of biogenic secondary organic aerosol (SOA) to contribute to the concentration of cloud condensation nuclei (CCN) in the atmosphere is examined.
Abstract: [1] The ability of biogenic secondary organic aerosol (SOA) to contribute to the concentration of cloud condensation nuclei (CCN) in the atmosphere is examined. Aerosol is generated by the ozonolysis reaction of monoterpenes (α-pinene, β-pinene, 3-carene, and limonene) and sesquiterpenes (β-caryophyllene, α-humulene, and o-cedrene) in a 10 m 3 temperature-controlled Teflon smog chamber. In some cases, a self-seeding technique is used, which enables high particle concentrations with the desired diameters without compromising particle composition and purity. The monoterpene SOA is excellent CCN material, and it activates similarly (average activation diameter equals 48 ± 8 nm at 1% supersaturation for the species used in this work) to highly water-soluble organic species. Its effective solubility in water was estimated to be in the range of 0.07- 0.40 g solute/g H 2 O. CCN measurements for sesquiterpene SOA (average activation diameter equals 120 ± 20 nm at 1% supersaturation for the species used in this work) show that it is less CCN active than monoterpene SOA. The initial terpene mixing ratio (between 3 and 100 ppb) does not affect the CCN activation for freshly generated SOA.

123 citations

Journal ArticleDOI
TL;DR: In this article, a study of 40 primary school students' (ages between 11 and 12 years) conceptions concerning the greenhouse effect was conducted, which led to the formation of seven distinct models of thinking regarding this environmental phenomenon.
Abstract: Individual, semistructured interviews were used for the study of 40 primary school students' (ages between 11 and 12 years) conceptions concerning the greenhouse effect. Analysis of the data led to the formation of seven distinct models of thinking regarding this environmental phenomenon. The inferred models are differentiated according to the following criteria: (a) the position and distribution of the greenhouse gases; (b) the existence of connections between the greenhouse effect and the ozone layer, or its depletion; and (c) the types of radiation considered to be involved in the greenhouse effect. However, children's models involve a common core of beliefs, according to which the greenhouse effect is due to solar radiation that heats up the earth and the atmosphere, while getting trapped by certain atmospheric gases, and severely changes the climate, melts the polar ice, and raises the sea level. Furthermore, the alternative conceptions involved in students' models are systematically examined to establish their teaching implications. The main teaching implications discussed here concern: (a) the concept of uniform diffusion of atmospheric gases; (b) the conceptual distinction between ultraviolet and other forms of solar radiation; (c) the conceptual distinction between sunlight and terrestrial radiation; and (d) the conceptual distinction between the roles of the ozone layer and greenhouse gases in the atmosphere. These teaching implications might consititute a valuable research tool for the determination of appropriate educational goals and conditions. © 1999 John Wiley & Sons, Inc. Sci Ed83:559–576, 1999.

123 citations

Journal ArticleDOI
TL;DR: In patients with HTPR after PCI, prasugrel is more effective compared with high clopidogrel in reducing platelet reactivity, particularly in CYP2C19*2 carriers.
Abstract: Objectives The primary aim of the study was to determine the antiplatelet effects of prasugrel versus high-dose clopidogrel in patients with high on-treatment platelet reactivity (HTPR) after percutaneous coronary intervention (PCI) and, secondarily, their relation to cytochrome (CYP) 2C19*2 carriage. Background High on-treatment platelet reactivity after clopidogrel administration after PCI is linked to the loss-of-function CYP2C19*2 allele and accompanied by an increased risk of adverse events. Methods We performed a prospective, randomized, single-blind, crossover study of platelet inhibition by prasugrel 10 mg/day versus high-dose 150 mg/day clopidogrel in 71 (of 210 screened; 33.8%) post-PCI patients with HTPR. Platelet function was assessed by the VerifyNow assay (Accumetrics, San Diego, California), and real-time polymerase chain reaction genotyping was performed for CYP2C19*2 carriage. Results The primary endpoint of platelet reactivity (measured in platelet reactivity units) at the end of the 2 treatment periods was lower after prasugrel compared with clopidogrel (least-squares estimates 129.4, 95% confidence interval [CI]: 111.1 to 147.7 versus 201.7, 95% CI: 183.2 to 220.2; p Conclusions In patients with HTPR after PCI, prasugrel is more effective compared with high clopidogrel in reducing platelet reactivity, particularly in CYP2C19*2 carriers. Genotyping guidance might be helpful only in case an increased clopidogrel maintenance dose is considered. (Prasugrel Versus High Dose Clopidogrel in Clopidogrel Resistant Patients Post Percutaneous Coronary Intervention (PCI); NCT01109784)

123 citations

Journal ArticleDOI
TL;DR: A two-degree-of-freedom nonlinear proportional-integral-derivative structure is being synthesized, providing ameliorated compensation of the PMAs' nonlinear hysteretic phenomena and advanced robustness through disturbance cancellation.
Abstract: In this paper, the positioning control problem of pneumatic muscle actuators (PMAs) is being considered. A two-degree-of-freedom nonlinear proportional-integral-derivative structure is being synthesized, providing ameliorated compensation of the PMAs' nonlinear hysteretic phenomena and advanced robustness through disturbance cancellation. Experimental studies are being utilized to prove the overall efficiency of the proposed control scheme with regard to set-point tracking performance for the position control of a single PMA, torsion angle control of a nonsymmetrical antagonistic PMA setup, and disturbance rejection in both single and antagonistic control scenarios.

122 citations


Authors

Showing all 13529 results

NameH-indexPapersCitations
Thomas J. Meyer120107868519
Thoralf M. Sundt11275555708
Chihaya Adachi11290861403
Eleftherios P. Diamandis110106452654
Roland Siegwart105115451473
T. Geralis9980852221
Spyros N. Pandis9737751660
Michael Tsapatsis7737520051
George K. Karagiannidis7665324066
Eleftherios Mylonakis7544821413
Matthias Mörgelin7533218711
Constantinos C. Stoumpos7519427991
Raymond Alexanian7521121923
Mark J. Ablowitz7437427715
John Lygeros7366721508
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202395
2022250
20211,738
20201,672
20191,469
20181,443