Jørgensen, Martin Balslev; Hageman, Ida
2009-01-01
Folie à deux or induced psychotic disorder is a rare psychiatric illness. The essential feature is a psychotic disorder shared by two emotionally close persons, usually close relatives. The disorder is characterized by a primary psychotic person who gradually imposes her delusional beliefs on the...... other person. The disorder usually resolves in the more passive person when the two are separated (e.g. by admittance of the primary psychotic person). This case report describes a shared delusional belief between two friends. Udgivelsesdato: 2009-Dec-14...
2009-01-01
Folie à deux or induced psychotic disorder is a rare psychiatric illness. The essential feature is a psychotic disorder shared by two emotionally close persons, usually close relatives. The disorder is characterized by a primary psychotic person who gradually imposes her delusional beliefs on the...... other person. The disorder usually resolves in the more passive person when the two are separated (e.g. by admittance of the primary psychotic person). This case report describes a shared delusional belief between two friends. Udgivelsesdato: 2009-Dec...
The French nuclear waste regulation requires the classification of nuclear waste into several categories according to the radioactive activity and the nature of the isotopes. According to this classification, a set of constraints to be respected for the processing of the packaging has been established in order to authorize the storage in a final surface repository. These constraints are very drastic and the repositories are managed by an independent institute. Furthermore, there are several kinds of packaging (from big bags to big containers). For each of them, depending on the waste category to be put inside, all the possible verifications and measurements have to be carried out to be sure that the agreement is entirely respected. The CARAIBES database appeared in 1999 and is presently used by all the nuclear research centres of the Commissariat a l'Energie Atomique. It was designed to assist people in the process of making up waste packaging in order to guarantee its release to a surface repository. All the data, ranging from the physical characteristics of the waste to more than three hundred efficiency curves necessary to assess the activity of the radio-nuclides measured by gamma spectrometry, are embodied into the framework of a Relational Database Management System in order to centralize and guarantee the coherence of the collected data. This framework is closely linked to the release approval, integrating the activity thresholds calculation early in the life cycle in order to choose the proper orientation for every waste packaging. The CARAIBES database is regularly audited by an independent institute in order to verify the good behaviour of the process which controls the compliance of the final packaging in terms of activity and nature of the waste before giving the authorisation for shipment to a surface repository. The people in charge of the database maintenance have to allow for the evolution concerning both the framework of the database and the
Borel, François
2015-01-01
Guinée : les Peuls du Wassolon — la danse des chasseurs. Enregistrements : Patrick Larue ; textes, traduction et commentaires : Patricia Pailleaud, Daniela Langer et Abdoulaye Diarra. 1 CD (DDD) OCORA C 558679, 1987. En coédition avec Les Films du Village. Nomades du désert : les Peulhs du Niger. Enregistrements, textes et production : Roselyne François et Manuel Gomes. 1 CD Playa Sound PS 65009, [1987]. Ces deux disques, publiés en 1987, ont un seul point commun, qui justifie d’ailleurs ce c...
Flicek, Paul; Amode, M Ridwan; Barrell, Daniel; Beal, Kathryn; Brent, Simon; Carvalho-Silva, Denise; Clapham, Peter; Coates, Guy; Fairley, Susan; Fitzgerald, Stephen; Gil, Laurent; Gordon, Leo; Hendrix, Maurice; Hourlier, Thibaut; Johnson, Nathan; Kähäri, Andreas K; Keefe, Damian; Keenan, Stephen; Kinsella, Rhoda; Komorowska, Monika; Koscielny, Gautier; Kulesha, Eugene; Larsson, Pontus; Longden, Ian; McLaren, William; Muffato, Matthieu; Overduin, Bert; Pignatelli, Miguel; Pritchard, Bethan; Riat, Harpreet Singh; Ritchie, Graham R S; Ruffier, Magali; Schuster, Michael; Sobral, Daniel; Tang, Y Amy; Taylor, Kieron; Trevanion, Stephen; Vandrovcova, Jana; White, Simon; Wilson, Mark; Wilder, Steven P; Aken, Bronwen L; Birney, Ewan; Cunningham, Fiona; Dunham, Ian; Durbin, Richard; Fernández-Suarez, Xosé M; Harrow, Jennifer; Herrero, Javier; Hubbard, Tim J P; Parker, Anne; Proctor, Glenn; Spudich, Giulietta; Vogel, Jan; Yates, Andy; Zadissa, Amonida; Searle, Stephen M J
2012-01-01
The Ensembl project (http://www.ensembl.org) provides genome resources for chordate genomes with a particular focus on human genome data as well as data for key model organisms such as mouse, rat and zebrafish. Five additional species were added in the last year including gibbon (Nomascus leucogenys) and Tasmanian devil (Sarcophilus harrisii) bringing the total number of supported species to 61 as of Ensembl release 64 (September 2011). Of these, 55 species appear on the main Ensembl website and six species are provided on the Ensembl preview site (Pre!Ensembl; http://pre.ensembl.org) with preliminary support. The past year has also seen improvements across the project. PMID:22086963
Flicek, Paul; Amode, M. Ridwan; Barrell, Daniel; Beal, Kathryn; Brent, Simon; Carvalho-Silva, Denise; Clapham, Peter; Coates, Guy; Fairley, Susan; Fitzgerald, Stephen; Gil, Laurent; Gordon, Leo; Hendrix, Maurice; Hourlier, Thibaut; Johnson, Nathan
2011-01-01
The Ensembl project (http://www.ensembl.org) provides genome resources for chordate genomes with a particular focus on human genome data as well as data for key model organisms such as mouse, rat and zebrafish. Five additional species were added in the last year including gibbon (Nomascus leucogenys) and Tasmanian devil (Sarcophilus harrisii) bringing the total number of supported species to 61 as of Ensembl release 64 (September 2011). Of these, 55 species appear on the main Ensembl website ...
Re, Matteo; Valentini, Giorgio
2012-03-01
Ensemble methods are statistical and computational learning procedures reminiscent of the human social learning behavior of seeking several opinions before making any crucial decision. The idea of combining the opinions of different "experts" to obtain an overall “ensemble” decision is rooted in our culture at least from the classical age of ancient Greece, and it has been formalized during the Enlightenment with the Condorcet Jury Theorem[45]), which proved that the judgment of a committee is superior to those of individuals, provided the individuals have reasonable competence. Ensembles are sets of learning machines that combine in some way their decisions, or their learning algorithms, or different views of data, or other specific characteristics to obtain more reliable and more accurate predictions in supervised and unsupervised learning problems [48,116]. A simple example is represented by the majority vote ensemble, by which the decisions of different learning machines are combined, and the class that receives the majority of “votes” (i.e., the class predicted by the majority of the learning machines) is the class predicted by the overall ensemble [158]. In the literature, a plethora of terms other than ensembles has been used, such as fusion, combination, aggregation, and committee, to indicate sets of learning machines that work together to solve a machine learning problem [19,40,56,66,99,108,123], but in this chapter we maintain the term ensemble in its widest meaning, in order to include the whole range of combination methods. Nowadays, ensemble methods represent one of the main current research lines in machine learning [48,116], and the interest of the research community on ensemble methods is witnessed by conferences and workshops specifically devoted to ensembles, first of all the multiple classifier systems (MCS) conference organized by Roli, Kittler, Windeatt, and other researchers of this area [14,62,85,149,173]. Several theories have been
Re, Matteo; Valentini, Giorgio
2012-03-01
Ensemble methods are statistical and computational learning procedures reminiscent of the human social learning behavior of seeking several opinions before making any crucial decision. The idea of combining the opinions of different "experts" to obtain an overall “ensemble” decision is rooted in our culture at least from the classical age of ancient Greece, and it has been formalized during the Enlightenment with the Condorcet Jury Theorem[45]), which proved that the judgment of a committee is superior to those of individuals, provided the individuals have reasonable competence. Ensembles are sets of learning machines that combine in some way their decisions, or their learning algorithms, or different views of data, or other specific characteristics to obtain more reliable and more accurate predictions in supervised and unsupervised learning problems [48,116]. A simple example is represented by the majority vote ensemble, by which the decisions of different learning machines are combined, and the class that receives the majority of “votes” (i.e., the class predicted by the majority of the learning machines) is the class predicted by the overall ensemble [158]. In the literature, a plethora of terms other than ensembles has been used, such as fusion, combination, aggregation, and committee, to indicate sets of learning machines that work together to solve a machine learning problem [19,40,56,66,99,108,123], but in this chapter we maintain the term ensemble in its widest meaning, in order to include the whole range of combination methods. Nowadays, ensemble methods represent one of the main current research lines in machine learning [48,116], and the interest of the research community on ensemble methods is witnessed by conferences and workshops specifically devoted to ensembles, first of all the multiple classifier systems (MCS) conference organized by Roli, Kittler, Windeatt, and other researchers of this area [14,62,85,149,173]. Several theories have been
2002-01-01
NYYD Ensemble'i duost Traksmann - Lukk E.-S. Tüüri teosega "Symbiosis", mis on salvestatud ka hiljuti ilmunud NYYD Ensemble'i CDle. 2. märtsil Rakvere Teatri väikeses saalis ja 3. märtsil Rotermanni Soolalaos, kavas Tüür, Kaumann, Berio, Reich, Yun, Hauta-aho, Buckinx
Les techniques d’optimisation multicritère en optimisation à deux niveaux
Pieume, Calice Olivier
2011-01-01
Cette thèse aborde l'optimisation multicritère et l'optimisation à deux niveaux. L'investigation porte principalement sur les méthodes, les applications et les liens possibles entre les deux classes d'optimisation. Premièrement, nous développons une méthode de résolution des problèmes d'optimisation linéaire multicritère. Pour ce faire, nous introduisons une nouvelle caractérisation des faces efficaces et exploitons le résultat selon lequel l'ensemble des tableaux idéaux associés aux sommets ...
Trichobezoar gastrique - à propos de deux cas
Karim Ibn Majdoub Hassani
2010-09-01
Full Text Available Le trichobezoar gastrique est une affection rare (un peu plus d’une dizaine de cas dans la littérature, qui affecte essentiellement des jeunes filles perturbées par des désordres psychologiques. Les auteurs rapportent deux cas de jeunes filles, hospitalisées pour volumineuse masse épigastrique. La fibroscopie gastrique a posé le diagnostic de trichobezoar. Une exérèse chirurgicale a été réalisée à travers une gastrotomie, sans complications. Un suivi psychiatrique des deux patientes a été recommandé. Le trichobezoar gastrique désigne l’accumulation inhabituelle de cheveux au niveau de l’estomac. Son diagnostic est facile en présence d’un contexte de trichophagie évocateur. La fibroscopie œsogastroduodénale est l’examen de référence permettant la visualisation du trichobezoar dont le traitement est essentiellement chirurgical.
NONE
2004-07-01
This report comments the reasons of the signature of the agreement between France, EURATOM and the IAEA for the reinforcement of IAEA's non-proliferation controls in the South America and Caribbean areas (law project no. 1329). The ratification of this agreement will have only few concrete consequences but will contribute to the promotion of non-proliferation and to the enforcement of warranties in the framework of the treaty of interdiction of nuclear weapons in South America and in the Caribbean area (signed in Vienna, Austria, on March 21, 2000). The commission of foreign affairs adopted this law project on March 3, 2004. (J.S.)
NONE
2004-01-01
The French Senate adopted on January 6, 2004 the project of law which authorizes the ratification of the agreement between France, the European atomic energy community and the IAEA about the enforcement of warranties in the framework of the treaty of interdiction of nuclear weapons in South America and in the Caribbean area signed in Vienna (Austria) on March 21, 2000. The text of this treaty is attached to this law. (J.S.)
Bergère, Marc
2015-01-01
Par leur dimension totale, les deux guerres mondiales ont affecté l'ensemble des rapports sociaux. Elles invitent donc tout particulièrement à questionner le masculin et le féminin. Dans cette dynamique, la répression judiciaire des faits de la collaboration avec l'ennemi constitue un observatoire d'autant plus privilégié que, dans les deux cas, elle traduit un moment spécifique du rapport des sexes à la justice. Dès lors, après avoir établi les faits, il nous importera surtout de clarifier l...
Intrication de deux atomes en utilisant le blocage de Rydberg
Gaëtan, A.
2010-12-01
Considérons un système quantique constitué de deux sous-systèmes : on dit qu'il est dans un état intriqué s'il existe des corrélations quantiques entre les états de ces derniers. La compréhension et la mise en œuvre d'états intriqués ont de nombreuses applications (métrologie quantique, étude des systèmes fortement corrélés, traitement quantique de l'information, etc.) et constituent le contexte général de ce travail de thèse. Plus en détail, nous démontrons la réalisation d'un état intriqué de deux atomes neutres piégés indépendamment. Pour cela, nous exploitons le phénomène de blocage de Rydberg : lorsqu'on essaie d'exciter simultanément deux atomes séparés de quelques micromètres vers un état de Rydberg donné, la forte interaction entre atomes de Rydberg peut empêcher cette excitation simultanée. Dans ce cas, seul un des deux atomes est excité et l'on génère ainsi des corrélations quantiques entre les états des deux atomes, c'est-à-dire de l'intrication. Dans notre expérience, deux atomes de 87Rb dans l'état fondamental 5S1/2 sont piégés chacun dans une pince optique microscopique, à une distance relative de 4 micromètres. En réalisant des transitions entre l'état 5S1/2 et l'état de Rydberg 58D3/2 par des transitions à deux photons, nous obtenons un état intriqué des deux atomes dans les sous-niveaux |5S1/2, f = 1, mf = 1> et |5S1/2, f = 2, mf = 2>. Afin de quantifier l'intrication, nous mesurons la fidélité par rapport à l'état-cible en réalisant des transitions Raman entre ces deux sous-niveaux. La fidélité des paires d'atomes présentes à la fin de l'expérience est supérieure à la valeur seuil de 0,5, ce qui prouve la création d'un état intriqué.
Ensemble clustering in deterministic ensemble Kalman filters
Javier Amezcua
2012-07-01
Full Text Available Ensemble clustering (EC can arise in data assimilation with ensemble square root filters (EnSRFs using non-linear models: an M-member ensemble splits into a single outlier and a cluster of M–1 members. The stochastic Ensemble Kalman Filter does not present this problem. Modifications to the EnSRFs by a periodic resampling of the ensemble through random rotations have been proposed to address it. We introduce a metric to quantify the presence of EC and present evidence to dispel the notion that EC leads to filter failure. Starting from a univariate model, we show that EC is not a permanent but transient phenomenon; it occurs intermittently in non-linear models. We perform a series of data assimilation experiments using a standard EnSRF and a modified EnSRF by a resampling though random rotations. The modified EnSRF thus alleviates issues associated with EC at the cost of traceability of individual ensemble trajectories and cannot use some of algorithms that enhance performance of standard EnSRF. In the non-linear regimes of low-dimensional models, the analysis root mean square error of the standard EnSRF slowly grows with ensemble size if the size is larger than the dimension of the model state. However, we do not observe this problem in a more complex model that uses an ensemble size much smaller than the dimension of the model state, along with inflation and localisation. Overall, we find that transient EC does not handicap the performance of the standard EnSRF.
Online Learning with Ensembles
Urbanczik, R
1999-01-01
Supervised online learning with an ensemble of students randomized by the choice of initial conditions is analyzed. For the case of the perceptron learning rule, asymptotically the same improvement in the generalization error of the ensemble compared to the performance of a single student is found as in Gibbs learning. For more optimized learning rules, however, using an ensemble yields no improvement. This is explained by showing that for any learning rule $f$ a transform $\\tilde{f}$ exists,...
Morphing ensemble Kalman filters
Beezley, Jonathan D.; Mandel, Jan
2008-01-01
A new type of ensemble filter is proposed, which combines an ensemble Kalman filter (EnKF) with the ideas of morphing and registration from image processing. This results in filters suitable for non-linear problems whose solutions exhibit moving coherent features, such as thin interfaces in wildfire modelling. The ensemble members are represented as the composition of one common state with a spatial transformation, called registration mapping, plus a residual. A fully automatic registration m...
Morphing Ensemble Kalman Filters
Beezley, Jonathan D.; Mandel, Jan
2007-01-01
A new type of ensemble filter is proposed, which combines an ensemble Kalman filter (EnKF) with the ideas of morphing and registration from image processing. This results in filters suitable for nonlinear problems whose solutions exhibit moving coherent features, such as thin interfaces in wildfire modeling. The ensemble members are represented as the composition of one common state with a spatial transformation, called registration mapping, plus a residual. A fully automatic registration met...
L'entre-deux-guerres mathématique à travers les thèses soutenues en France
Leloup, Juliette
2009-01-01
L'entre-deux-guerres mathématique est étudié à partir des 242 thèses en sciences mathématiques soutenues en France. Ce corpus est analysé à trois niveaux différents. L'analyse de premier niveau consiste en une analyse quantitative de l'ensemble des doctorats. Elle permet de mettre en évidence les équilibres entre les différents domaines des sciences mathématiques et les différentes facultés de France, celle de Paris et celles de province. Les thèses soutenues en province sont alors étudiées s...
Multilevel ensemble Kalman filtering
Hoel, Håkon; Law, Kody J. H.; Tempone, Raul
2015-01-01
This work embeds a multilevel Monte Carlo (MLMC) sampling strategy into the Monte Carlo step of the ensemble Kalman filter (ENKF), thereby yielding a multilevel ensemble Kalman filter (MLENKF) which has provably superior asymptotic cost to a given accuracy level. The theoretical results are illustrated numerically.
Bureš, Tomáš; Krijt, F.; Plášil, F.; Hnětynka, P.; Jiráček, Z.
New York,: ACM, 2015, Article No. 17. ISBN 978-1-4503-3393-1. [ECSAW '15. European Conference on Software Architecture Workshops. Dubrovnik (HR), 07.09.2015-08.09.2015] Institutional support: RVO:67985807 Keywords : distributed coordination * architectural adaptation * ensemble-based component systems * component model * emergent architecture * component ensembles * autonomic systems Subject RIV: JC - Computer Hardware ; Software
Deux approches du risque d'inondation en France
Bruno LEDOUX
1994-12-01
Full Text Available En France, les sources d’informations centralisées sur les risques naturels sont rares. Pourtant, une politique de prévention engagée par l’État nécessite de disposer d’une information à l’échelle nationale, d’évaluer les enjeux et de mobiliser les acteurs. Deux sources d’informations sont décrites et exploitées, qui permettent, par une représentation cartographique nationale, d’amorcer analyses et débats.
Syndrome de Rhupus: à propos de deux observations
Hachicha, Imen; Fourati, Hela; Akrout, Rim; Baklouti, Sofien
2012-01-01
L'association lupus érythémateux systémique et polyarthrite rhumatoïde (rhupus)est une condition clinique rare. A travers le monde 50 cas de Rhupus ont été décrits. Nous en rapportons deux nouvelles observations de patientes Tunisiennes qui présentaient une polyarthrite érosive à prédominance distale avec des anticorps anti Sm positifs dans un cas et des anti-DNA natifs dans l'autre cas.
A Classifier Ensemble of Binary Classifier Ensembles
Sajad Parvin
2011-09-01
Full Text Available This paper proposes an innovative combinational algorithm to improve the performance in multiclass classification domains. Because the more accurate classifier the better performance of classification, the researchers in computer communities have been tended to improve the accuracies of classifiers. Although a better performance for classifier is defined the more accurate classifier, but turning to the best classifier is not always the best option to obtain the best quality in classification. It means to reach the best classification there is another alternative to use many inaccurate or weak classifiers each of them is specialized for a sub-space in the problem space and using their consensus vote as the final classifier. So this paper proposes a heuristic classifier ensemble to improve the performance of classification learning. It is specially deal with multiclass problems which their aim is to learn the boundaries of each class from many other classes. Based on the concept of multiclass problems classifiers are divided into two different categories: pairwise classifiers and multiclass classifiers. The aim of a pairwise classifier is to separate one class from another one. Because of pairwise classifiers just train for discrimination between two classes, decision boundaries of them are simpler and more effective than those of multiclass classifiers.The main idea behind the proposed method is to focus classifier in the erroneous spaces of problem and use of pairwise classification concept instead of multiclass classification concept. Indeed although usage of pairwise classification concept instead of multiclass classification concept is not new, we propose a new pairwise classifier ensemble with a very lower order. In this paper, first the most confused classes are determined and then some ensembles of classifiers are created. The classifiers of each of these ensembles jointly work using majority weighting votes. The results of these ensembles
National Aeronautics and Space Administration — Ensemble Data Mining Methods, also known as Committee Methods or Model Combiners, are machine learning methods that leverage the power of multiple models to achieve...
Marin-Garcia Pablo
2010-05-01
Full Text Available Abstract Background The maturing field of genomics is rapidly increasing the number of sequenced genomes and producing more information from those previously sequenced. Much of this additional information is variation data derived from sampling multiple individuals of a given species with the goal of discovering new variants and characterising the population frequencies of the variants that are already known. These data have immense value for many studies, including those designed to understand evolution and connect genotype to phenotype. Maximising the utility of the data requires that it be stored in an accessible manner that facilitates the integration of variation data with other genome resources such as gene annotation and comparative genomics. Description The Ensembl project provides comprehensive and integrated variation resources for a wide variety of chordate genomes. This paper provides a detailed description of the sources of data and the methods for creating the Ensembl variation databases. It also explores the utility of the information by explaining the range of query options available, from using interactive web displays, to online data mining tools and connecting directly to the data servers programmatically. It gives a good overview of the variation resources and future plans for expanding the variation data within Ensembl. Conclusions Variation data is an important key to understanding the functional and phenotypic differences between individuals. The development of new sequencing and genotyping technologies is greatly increasing the amount of variation data known for almost all genomes. The Ensembl variation resources are integrated into the Ensembl genome browser and provide a comprehensive way to access this data in the context of a widely used genome bioinformatics system. All Ensembl data is freely available at http://www.ensembl.org and from the public MySQL database server at ensembldb.ensembl.org.
Louppe, Gilles; Geurts, Pierre
2012-01-01
In this paper, we consider supervised learning under the assumption that the available memory is small compared to the dataset size. This general framework is relevant in the context of big data, distributed databases and embedded systems. We investigate a very simple, yet effective, ensemble framework that builds each individual model of the ensemble from a random patch of data obtained by drawing random subsets of both instances and features from the whole dataset. We carry out an extensive...
Du Lac de Geneve au Lac Baikal: deux metropoles en construction
Guy Mettan
2006-08-01
'Annemasse dans un ensemble qui atteindrait environ un million d'habitants au total. Le lac Leman (Lac de Geneve faisant office de point commun entre ces villes, la region prendrait le nom de metropole lemanique ou de Bassin lemanique. Ce qui a pour avantage de ne pas mettre Geneve trop en evidence et de ne pas vexer les autres villes dont les noms seraient menaces de disparaitre au profit de Geneve.Pour reussir, ce rapprochement doit respecter quelques principes fondamentaux :1 developper les infrastructures communes et les moyens de communication entre les villes partenaires : la gestion de l''aeroport international de Geneve a ainsi ete ouvert a la France et aux representants de Lausanne. On projette de construire une troisieme voie pour l'autoroute et la ligne de chemin de fer qui relie Geneve a Lausanne. Sur le plan politique, les deputes des deux provin2ces militent dans la meme direction.2 respecter les identites traditionnelles et developper une identite commune autour d'un projet rassembleur. Le projet de fusion a echoue parce qu'il niait l'histoire et les traditions propres a chaque ville. Sans territoire et de tradition protestante calviniste, Geneve est universitaire, internationale, tres urbaine. Lausanne est lutherienne et plus enracinee dans une region agricole et viticole. La culture et l'economie, et surtout la fiscalite ne sont pas les memes. Cela reconnu, il convient malgre tout de developper des projets communs, qui rassemblent les habitants des deux regions et puissent peu a peu forger l'idee d'un destin commun. Pour Geneve et Lausanne, ce pourrait etre la vocation internationale, Geneve etant connue pour ses organisations internationales liees et le siege europeen de l'ONU tandis que Lausanne est devenue la capitale internationale du sport avec le CIO (Comite international olympique et federations sportives. Un deuxieme axe est de profiler l'ensemble de la metropole comme une region du savoir, avec ses universites, ses sieges d'entreprises multinationales et
Outils de perçage à deux moteurs coaxiaux
MORARU, George; FRANGEARD, Didier
2015-01-01
La présente invention concerne le domaine de l’usinage par enlèvement de matière. L’invention a ainsi pour objet une machine d’usinage et, plus particulièrement, une machine de perçage ou de fraisage. La machine à la particularité d’intégrer deux moteurs électriques destinés à contrôler les mouvements d’avance et de rotation d’un outil, tout en permettant une action d’assistance vibratoire, particulièrement utile pour le perçage de matériaux difficiles à usiner.
Die dramatiese discours in Pas de deux van Hugo Claus
R. Vaughan
1990-05-01
Full Text Available Drama is action, verbal drama is speech action, and the dramatic text is subject to a similar set of rules as that governing the extra-literary communication situation. Dramatic irony, the very essence of drama itself, is generated by a dual, mutually interactive process of communication, whereby the audience is “written into” the text in a way distinguishing it from other literary genres, and by a systematic flouting of the rules governing communication. Pas de deux demonstrates the peculiar duality of dramatic discourse by its complex exploitation of the breakdown/non-breakdown of Grice’s Co-operative Principle-. communication/non-communication becomes reversible and, therefore, mutually constitutive concepts “releasing meaning” and conveying the “ideology” of this play.
Un capteur d'extensométrie miniature à deux voies
FERRAND, J.C.
1982-01-01
Un capteur d’extensométrie miniature à deux voies a été réalisé. Il permet de mesurer les déformations dans deux directions perpendiculaires, et sa sensibilité est de 5 microdéformations. Il s’applique sur le bois sans collage.
The semantic similarity ensemble
Andrea Ballatore
2013-12-01
Full Text Available Computational measures of semantic similarity between geographic terms provide valuable support across geographic information retrieval, data mining, and information integration. To date, a wide variety of approaches to geo-semantic similarity have been devised. A judgment of similarity is not intrinsically right or wrong, but obtains a certain degree of cognitive plausibility, depending on how closely it mimics human behavior. Thus selecting the most appropriate measure for a specific task is a significant challenge. To address this issue, we make an analogy between computational similarity measures and soliciting domain expert opinions, which incorporate a subjective set of beliefs, perceptions, hypotheses, and epistemic biases. Following this analogy, we define the semantic similarity ensemble (SSE as a composition of different similarity measures, acting as a panel of experts having to reach a decision on the semantic similarity of a set of geographic terms. The approach is evaluated in comparison to human judgments, and results indicate that an SSE performs better than the average of its parts. Although the best member tends to outperform the ensemble, all ensembles outperform the average performance of each ensemble's member. Hence, in contexts where the best measure is unknown, the ensemble provides a more cognitively plausible approach.
Imprinting and recalling cortical ensembles.
Carrillo-Reid, Luis; Yang, Weijian; Bando, Yuki; Peterka, Darcy S; Yuste, Rafael
2016-08-12
Neuronal ensembles are coactive groups of neurons that may represent building blocks of cortical circuits. These ensembles could be formed by Hebbian plasticity, whereby synapses between coactive neurons are strengthened. Here we report that repetitive activation with two-photon optogenetics of neuronal populations from ensembles in the visual cortex of awake mice builds neuronal ensembles that recur spontaneously after being imprinted and do not disrupt preexisting ones. Moreover, imprinted ensembles can be recalled by single- cell stimulation and remain coactive on consecutive days. Our results demonstrate the persistent reconfiguration of cortical circuits by two-photon optogenetics into neuronal ensembles that can perform pattern completion. PMID:27516599
Hansen, Lars Kai; Salamon, Peter
1990-01-01
We propose several means for improving the performance an training of neural networks for classification. We use crossvalidation as a tool for optimizing network parameters and architecture. We show further that the remaining generalization error can be reduced by invoking ensembles of similar...... networks....
Le facteur temps ne sonne jamais deux fois
Klein, Etienne
2009-01-01
Chose déroutante, décidément, que le temps. Nous en parlons comme d'une notion familière, évidente, voire domestique, "gérable". Nous parlons même d'un "temps réel" pour évoquer l'instantanéité, c'est-à-dire le temps sur lequel nous n'avons aucune prise. Les physiciens, eux, l'ont couplé à l'espace, en ont fait une variable mathématique, abstraite, qu'ils intègrent dans des théories audacieuses, spectaculaires, si complexes qu'elles sont difficiles à traduire en langage courant. Certains disent même avoir identifié le moteur du temps. Quant aux philosophes, ils ne cessent depuis plus de deux millénaires de soumettre le temps au questionnement : est-il une sorte d'entité primitive, originaire, qui ne dériverait que d'elle-même? Ou procéderait-il au contraire d'une ou plusieurs autres entités, plus fondamentales: la relation de cause à effet, par exemple? Le temps s'écoule-t-il de lui-même ou a-t-il besoin des événements qui s'y déroulent pour passer? S'apparente-t-il au devenir,...
Kingston Soundpainting Ensemble
Minors, Helen Julia
2012-01-01
This performance is designed to introduce teachers and school musicians to this live multidisciplinary live composing sign language. Led by Dr. Helen Julia Minors (soundpainter, trumpet, voice), the Kingston Soundpainting Ensemble, led by Dr. Minors at Kington University, is representated by a section a varied set of performers, using woodwind, brass, voice and percussion, spanning popular, classical and world styles. This performance consists of: Philip Warda (electronic instruments,...
Effective Visualization of Temporal Ensembles.
Hao, Lihua; Healey, Christopher G; Bass, Steffen A
2016-01-01
An ensemble is a collection of related datasets, called members, built from a series of runs of a simulation or an experiment. Ensembles are large, temporal, multidimensional, and multivariate, making them difficult to analyze. Another important challenge is visualizing ensembles that vary both in space and time. Initial visualization techniques displayed ensembles with a small number of members, or presented an overview of an entire ensemble, but without potentially important details. Recently, researchers have suggested combining these two directions, allowing users to choose subsets of members to visualization. This manual selection process places the burden on the user to identify which members to explore. We first introduce a static ensemble visualization system that automatically helps users locate interesting subsets of members to visualize. We next extend the system to support analysis and visualization of temporal ensembles. We employ 3D shape comparison, cluster tree visualization, and glyph based visualization to represent different levels of detail within an ensemble. This strategy is used to provide two approaches for temporal ensemble analysis: (1) segment based ensemble analysis, to capture important shape transition time-steps, clusters groups of similar members, and identify common shape changes over time across multiple members; and (2) time-step based ensemble analysis, which assumes ensemble members are aligned in time by combining similar shapes at common time-steps. Both approaches enable users to interactively visualize and analyze a temporal ensemble from different perspectives at different levels of detail. We demonstrate our techniques on an ensemble studying matter transition from hadronic gas to quark-gluon plasma during gold-on-gold particle collisions. PMID:26529728
Shared Psychotic Disorder (Folie à Deux in Turkey
Buket Cinemre
2009-09-01
Full Text Available Shared psychotic disorder or folie à deux is a rare and relatively unknown syndrome. Large case series are needed to find out and clarify the etiological factors and the phenomenology of shared psychotic disorder by comparing the cases from different society and cultures. In this study, we reviewed all reported cases of shared psychotic disorder that had been published or presented in Turkey since 1962. To reach this aim, we have searched Pubmed/Medline, ScienceDirect, Google Scholar, Ulakbim Turkish Medical Index, Turkish Psychiatric Index databases for published records originating from Turkey. We have also manually searched poster abstract books of congresses held in Turkey between 1962 and 2009. All cases eligible for inclusion into this study have been evaluated one by one and grouped as primary or secondary cases. The features of these cases were investigated for a number of variables including age, sex, educational level, occupation, the presence of shared delusion and hallucinations, diagnosis, management, onset of illness, family history, IQ, social isolation, the nature of the relationship and classification system used for diagnosis. The results have showed that the syndrome is more frequently observed among women, within same family members and between sisters. Social isolation was the most common risk factor in these patients and most patients shared hallucinations with their partners along with their delusions. Several secondary cases required antipsychotic drugs for the treatment of their symptoms. Though these features were inline with literature findings, the present findings from Turkish population were different from previous studies with regards to the presence of olfactory hallucinations, absence of grandiose delusions and the number of affected family members. The results mostly supported the challenges and discussions in western countries. To understand this most pathological form of interpersonal relationships
Multilevel ensemble Kalman filtering
Hoel, Hakon
2016-06-14
This work embeds a multilevel Monte Carlo sampling strategy into the Monte Carlo step of the ensemble Kalman filter (EnKF) in the setting of finite dimensional signal evolution and noisy discrete-time observations. The signal dynamics is assumed to be governed by a stochastic differential equation (SDE), and a hierarchy of time grids is introduced for multilevel numerical integration of that SDE. The resulting multilevel EnKF is proved to asymptotically outperform EnKF in terms of computational cost versus approximation accuracy. The theoretical results are illustrated numerically.
Deux nouvelles lèvres de Cassidae au PPNB
Gaëlle Le Dosseur
2008-03-01
Full Text Available En 2008, deux nouvelles lèvres de Cassidae ont été mises au jour sur deux sites néolithiques (Néolithique Précéramique B : PPNB du Levant Sud : Beisamoun et Yiftahel. Il s’agit d’objets façonnés sur la lèvre externe de coquillages méditerranéens appelés Phalium granulatum. Des aménagements pour la suspension (perforations aux extrémités laissent penser que ces objets ont été utilisés comme pendentifs ou qu’ils ont été cousus sur des vêtements ou des accessoires. Ces découvertes alimentent la discussion sur l’approvisionnement en matières premières mais aussi sur les parentés culturelles et les singularités de chaque site à cette époque. Si l’usage de lèvres de Cassidae est partagé par de nombreux sites PPNB, les modes de fabrication et de suspension ne sont pas strictement les mêmes sur tous. Ces variations reflètent-elles une évolution des modes de suspension dans le temps (au cours du PPNB moyen/récent ? Ou révèlent-elles des choix « contemporains » distincts, qui contribueraient à définir l’identité propre de chaque site ? Après le Néolithique, l’usage des lèvres de Cassidae se poursuit aux Âges des métaux. À cette époque plus qu’au Néolithique, ces objets sont retrouvés dans des contextes funéraires. Il est difficile de savoir si cette situation résulte des méthodes de fouilles distinctes adoptées sur les sites néolithiques et sur ceux des Âges des métaux ou si elle est une réalité archéologique. Dans le second cas, on pourrait proposer que le sens donné aux lèvres de Cassidae, en partie reflété par le lieu de dépôt, a pu évoluer avec le temps.Two more cassid lips for the PPNBBeisamoun and Yiftahel In 2008, two new cassid lips have been found on two Neolithic sites (Pre Pottery Neolithic B, in the Southern Levant: Beisamoun and Yiftahel. These objects are shaped on the external lip of shells coming from the Mediterranean Sea and called Phalium
Multinomial logistic regression ensembles.
Lee, Kyewon; Ahn, Hongshik; Moon, Hojin; Kodell, Ralph L; Chen, James J
2013-05-01
This article proposes a method for multiclass classification problems using ensembles of multinomial logistic regression models. A multinomial logit model is used as a base classifier in ensembles from random partitions of predictors. The multinomial logit model can be applied to each mutually exclusive subset of the feature space without variable selection. By combining multiple models the proposed method can handle a huge database without a constraint needed for analyzing high-dimensional data, and the random partition can improve the prediction accuracy by reducing the correlation among base classifiers. The proposed method is implemented using R, and the performance including overall prediction accuracy, sensitivity, and specificity for each category is evaluated on two real data sets and simulation data sets. To investigate the quality of prediction in terms of sensitivity and specificity, the area under the receiver operating characteristic (ROC) curve (AUC) is also examined. The performance of the proposed model is compared to a single multinomial logit model and it shows a substantial improvement in overall prediction accuracy. The proposed method is also compared with other classification methods such as the random forest, support vector machines, and random multinomial logit model. PMID:23611203
L’histoire du malade. Croisement de deux anthropologies
Pauline Labey
2010-05-01
Full Text Available L’histoire des malades peut intégrer l’anthropologie de deux manières. Tout d’abord, elle peut utiliser l’anthropologie comme source de méthode et de questionnement. En écrivant une histoire de l’homme malade, l’historien se doit de saisir une situation corporelle individuelle et ses conséquences sociales dans un quotidien. Il interroge donc une société sur son rapport au corps, lorsqu’il est atteint par le mal, et sur son rapport à la norme, lorsqu’on s’en écarte. Ensuite, l’histoire des malades peut porter sur l’anthropologie comme discours, produit dans une période donnée. L’anthropologie est dès lors abordée en tant qu’objet de recherche. En croisant pratique et discours, il est possible de saisir les conséquences individuelles de l’évènement maladie. Pour le Moyen Age central, enjeux spirituels et enjeux institutionnels peuvent s’éclairer, grâce à cette double utilisation de l’anthropologie.The history of those who suffer from illness may integrate anthropology in two ways. First, anthropology can be used as method and a mode of questioning. In writing history of the sick, the historian must grasp a particular physiological situation and its social consequences in everyday life. He must question a society about its relationship with the body when it is affected by illness, and about what happens when an individual departs from the norm of health. Second, a history of the sick can use anthropology as a discourse, the product of a given period. In this case, anthropology is used as a subject of research. Combining practice and discourse, it is possible to apprehend individual consequences of an illness-event. This dual use of anthropology may clarify the spiritual and institutional consequences of illness in the central Middle Ages.La storia dei malati può integrare l’antropologia in due modi. In primo luogo, può utilizzare l’antropologia come fonte di metodi e di interrogativi
Representative Ensembles in Statistical Mechanics
V. I. YUKALOV
2007-01-01
The notion of representative statistical ensembles, correctly representing statistical systems, is strictly formulated. This notion allows for a proper description of statistical systems, avoiding inconsistencies in theory. As an illustration, a Bose-condensed system is considered. It is shown that a self-consistent treatment of the latter, using a representative ensemble, always yields a conserving and gapless theory.
2004-01-01
Within the framework of the PSO-Ensemble project (FU2101) a demo application has been created. The application use ECMWF ensemble forecasts. Two instances of the application are running; one for Nysted Offshore and one for the total production (except Horns Rev) in the Eltra area. The output is...
We discuss the geometry of trees endowed with a causal structure using the conventional framework of equilibrium statistical mechanics. We show how this ensemble is related to popular growing network models. In particular we demonstrate that on a class of afine attachment kernels the two models are identical but they can differ substantially for other choice of weights. We show that causal trees exhibit condensation even for asymptotically linear kernels. We derive general formulae describing the degree distribution, the ancestor--descendant correlation and the probability that a randomly chosen node lives at a given geodesic distance from the root. It is shown that the Hausdorff dimension dH of the causal networks is generically infinite. (author)
Bialas, Piotr
2003-10-01
We discuss the geometry of trees endowed with a causal structure using the conventional framework of equilibrium statistical mechanics. We show how this ensemble is related to popular growing network models. In particular we demonstrate that on a class of afine attachment kernels the two models are identical but they can differ substantially for other choice of weights. We show that causal trees exhibit condensation even for asymptotically linear kernels. We derive general formulae describing the degree distribution, the ancestor--descendant correlation and the probability that a randomly chosen node lives at a given geodesic distance from the root. It is shown that the Hausdorff dimension dH of the causal networks is generically infinite.
The nosological significance of Folie à Deux: a review of the literature
Patel Anish
2006-08-01
Full Text Available Abstract Background Folie à Deux is a rare syndrome that has attracted much clinical attention. There is increasing doubt over the essence of the condition and the validity of the original description, such that it remains an elusive entity difficult to define. Method We conducted a systematic review of the literature of all cases reporting the phenomenon of Folie à Deux, from the years 1993–2005. Results 64 cases were identified of which 42 met the inclusion criteria. The diagnoses in the primary and secondary were more heterogeneous than current diagnostic criteria suggest. There exists a high degree of similarity between the primary and secondary in terms of susceptibility to psychiatric illness, family and past psychiatric history, than previously thought. Conclusion Folie à Deux can occur in many situations outside the confines of the current classification systems and is not as rare as believed, and should alert the clinician to unrecognized psychiatric problems in the secondary.
Le lupus systémique juvénile familial: à propos de deux familles
Krich, Sanaa; Inani, Kawtar; Meziane, Mariame; Souilmi, Fatima Zohta; Atmani, Samir; Hida, Mustapha; Harmouch, Taoufik; Amarti, Afaf; Mernissi, Fatima Zohra
2015-01-01
Le lupus érythémateux systémique (LES) juvénile est une connectivite rare, d’évolution plus sévère que chez l'adulte. Les cas familiaux sont exceptionnels. Il s'agissait de deux familles (5 patients atteints), chez qui on a objectivé un LES juvénile chez deux sæurs âgées de 14 ans et 6 ans respectivement chez la première famille, deux frères, âgés de 20 ans et 6 ans respectivement plus une sæur âgée de 10 ans chez la deuxième famille. Dans tout les cas le diagnostic de lupus systémique a été ...
On Ensemble Nonlinear Kalman Filtering with Symmetric Analysis Ensembles
Luo, Xiaodong
2010-09-19
The ensemble square root filter (EnSRF) [1, 2, 3, 4] is a popular method for data assimilation in high dimensional systems (e.g., geophysics models). Essentially the EnSRF is a Monte Carlo implementation of the conventional Kalman filter (KF) [5, 6]. It is mainly different from the KF at the prediction steps, where it is some ensembles, rather then the means and covariance matrices, of the system state that are propagated forward. In doing this, the EnSRF is computationally more efficient than the KF, since propagating a covariance matrix forward in high dimensional systems is prohibitively expensive. In addition, the EnSRF is also very convenient in implementation. By propagating the ensembles of the system state, the EnSRF can be directly applied to nonlinear systems without any change in comparison to the assimilation procedures in linear systems. However, by adopting the Monte Carlo method, the EnSRF also incurs certain sampling errors. One way to alleviate this problem is to introduce certain symmetry to the ensembles, which can reduce the sampling errors and spurious modes in evaluation of the means and covariances of the ensembles [7]. In this contribution, we present two methods to produce symmetric ensembles. One is based on the unscented transform [8, 9], which leads to the unscented Kalman filter (UKF) [8, 9] and its variant, the ensemble unscented Kalman filter (EnUKF) [7]. The other is based on Stirling’s interpolation formula (SIF), which results in the divided difference filter (DDF) [10]. Here we propose a simplified divided difference filter (sDDF) in the context of ensemble filtering. The similarity and difference between the sDDF and the EnUKF will be discussed. Numerical experiments will also be conducted to investigate the performance of the sDDF and the EnUKF, and compare them to a well‐established EnSRF, the ensemble transform Kalman filter (ETKF) [2].
The Ensembl gene annotation system.
Aken, Bronwen L; Ayling, Sarah; Barrell, Daniel; Clarke, Laura; Curwen, Valery; Fairley, Susan; Fernandez Banet, Julio; Billis, Konstantinos; García Girón, Carlos; Hourlier, Thibaut; Howe, Kevin; Kähäri, Andreas; Kokocinski, Felix; Martin, Fergal J; Murphy, Daniel N; Nag, Rishi; Ruffier, Magali; Schuster, Michael; Tang, Y Amy; Vogel, Jan-Hinnerk; White, Simon; Zadissa, Amonida; Flicek, Paul; Searle, Stephen M J
2016-01-01
The Ensembl gene annotation system has been used to annotate over 70 different vertebrate species across a wide range of genome projects. Furthermore, it generates the automatic alignment-based annotation for the human and mouse GENCODE gene sets. The system is based on the alignment of biological sequences, including cDNAs, proteins and RNA-seq reads, to the target genome in order to construct candidate transcript models. Careful assessment and filtering of these candidate transcripts ultimately leads to the final gene set, which is made available on the Ensembl website. Here, we describe the annotation process in detail.Database URL: http://www.ensembl.org/index.html. PMID:27337980
Les archives ouvertes et la veille scientifique, deux axes de réflexion
Chazelas, M.; Courtial, F.; Dassa, M.; Jannik, J.; Jannès-Ober, E.; Martin, C.
2006-01-01
/ Compte rendu des communications présentées lors des Rencontres INIST/CNRS 2006 des professionnels de l'IST, portant sur deux thématiques : Archives institutionneles/archives ouvertes et veille scientifique/veille stratégique.
Kurt Hornik
2005-01-01
Cluster ensembles are collections of individual solutions to a given clustering problem which are useful or necessary to consider in a wide range of applications. The R package clue provides an extensible computational environment for creating and analyzing cluster ensembles, with basic data structures for representing partitions and hierarchies, and facilities for computing on these, including methods for measuring proximity and obtaining consensus and "secondary" clusterings....
Similarity measures for protein ensembles
Lindorff-Larsen, Kresten; Ferkinghoff-Borg, Jesper
2009-01-01
Analyses of similarities and changes in protein conformation can provide important information regarding protein function and evolution. Many scores, including the commonly used root mean square deviation, have therefore been developed to quantify the similarities of different protein conformations...... synthetic example from molecular dynamics simulations. We then apply the algorithms to revisit the problem of ensemble averaging during structure determination of proteins, and find that an ensemble refinement method is able to recover the correct distribution of conformations better than standard single...
The entropy of network ensembles
Bianconi, Ginestra
2008-01-01
In this paper we generalize the concept of random networks to describe networks with non trivial features by a statistical mechanics approach. This framework is able to describe ensembles of undirected, directed as well as weighted networks. These networks might have not trivial community structure or, in the case of networks embedded in a given space, non trivial distance dependence of the link probability. These ensembles are characterized by their entropy which evaluate the cardinality of ...
Quantum Gibbs ensemble Monte Carlo
We present a path integral Monte Carlo method which is the full quantum analogue of the Gibbs ensemble Monte Carlo method of Panagiotopoulos to study the gas-liquid coexistence line of a classical fluid. Unlike previous extensions of Gibbs ensemble Monte Carlo to include quantum effects, our scheme is viable even for systems with strong quantum delocalization in the degenerate regime of temperature. This is demonstrated by an illustrative application to the gas-superfluid transition of 4He in two dimensions
Deformed Ginibre ensembles and integrable systems
Orlov, A.Yu., E-mail: orlovs@ocean.ru
2014-01-17
We consider three Ginibre ensembles (real, complex and quaternion-real) with deformed measures and relate them to known integrable systems by presenting partition functions of these ensembles in form of fermionic expectation values. We also introduce double deformed Dyson–Wigner ensembles and compare their fermionic representations with those of Ginibre ensembles.
Localization of atomic ensembles via superfluorescence
Macovei, M.; Evers, J.; Keitel, C. H.; Zubairy, M. S.
2006-01-01
The sub-wavelength localization of an ensemble of atoms concentrated to a small volume in space is investigated. The localization relies on the interaction of the ensemble with a standing wave laser field. The light scattered in the interaction of standing wave field and atom ensemble depends on the position of the ensemble relative to the standing wave nodes. This relation can be described by a fluorescence intensity profile, which depends on the standing wave field parameters, the ensemble ...
Estimating preselected and postselected ensembles
Massar, Serge [Laboratoire d' Information Quantique, C.P. 225, Universite libre de Bruxelles (U.L.B.), Av. F. D. Rooselvelt 50, B-1050 Bruxelles (Belgium); Popescu, Sandu [H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Hewlett-Packard Laboratories, Stoke Gifford, Bristol BS12 6QZ (United Kingdom)
2011-11-15
In analogy with the usual quantum state-estimation problem, we introduce the problem of state estimation for a pre- and postselected ensemble. The problem has fundamental physical significance since, as argued by Y. Aharonov and collaborators, pre- and postselected ensembles are the most basic quantum ensembles. Two new features are shown to appear: (1) information is flowing to the measuring device both from the past and from the future; (2) because of the postselection, certain measurement outcomes can be forced never to occur. Due to these features, state estimation in such ensembles is dramatically different from the case of ordinary, preselected-only ensembles. We develop a general theoretical framework for studying this problem and illustrate it through several examples. We also prove general theorems establishing that information flowing from the future is closely related to, and in some cases equivalent to, the complex conjugate information flowing from the past. Finally, we illustrate our approach on examples involving covariant measurements on spin-1/2 particles. We emphasize that all state-estimation problems can be extended to the pre- and postselected situation. The present work thus lays the foundations of a much more general theory of quantum state estimation.
Ensemble algorithms in reinforcement learning.
Wiering, Marco A; van Hasselt, Hado
2008-08-01
This paper describes several ensemble methods that combine multiple different reinforcement learning (RL) algorithms in a single agent. The aim is to enhance learning speed and final performance by combining the chosen actions or action probabilities of different RL algorithms. We designed and implemented four different ensemble methods combining the following five different RL algorithms: Q-learning, Sarsa, actor-critic (AC), QV-learning, and AC learning automaton. The intuitively designed ensemble methods, namely, majority voting (MV), rank voting, Boltzmann multiplication (BM), and Boltzmann addition, combine the policies derived from the value functions of the different RL algorithms, in contrast to previous work where ensemble methods have been used in RL for representing and learning a single value function. We show experiments on five maze problems of varying complexity; the first problem is simple, but the other four maze tasks are of a dynamic or partially observable nature. The results indicate that the BM and MV ensembles significantly outperform the single RL algorithms. PMID:18632380
Ensemble Equivalence for Distinguishable Particles
Antonio Fernández-Peralta
2016-07-01
Full Text Available Statistics of distinguishable particles has become relevant in systems of colloidal particles and in the context of applications of statistical mechanics to complex networks. In this paper, we present evidence that a commonly used expression for the partition function of a system of distinguishable particles leads to huge fluctuations of the number of particles in the grand canonical ensemble and, consequently, to nonequivalence of statistical ensembles. We will show that the alternative definition of the partition function including, naturally, Boltzmann’s correct counting factor for distinguishable particles solves the problem and restores ensemble equivalence. Finally, we also show that this choice for the partition function does not produce any inconsistency for a system of distinguishable localized particles, where the monoparticular partition function is not extensive.
A mollified Ensemble Kalman filter
Bergemann, Kay
2010-01-01
It is well recognized that discontinuous analysis increments of sequential data assimilation systems, such as ensemble Kalman filters, might lead to spurious high frequency adjustment processes in the model dynamics. Various methods have been devised to continuously spread out the analysis increments over a fixed time interval centered about analysis time. Among these techniques are nudging and incremental analysis updates (IAU). Here we propose another alternative, which may be viewed as a hybrid of nudging and IAU and which arises naturally from a recently proposed continuous formulation of the ensemble Kalman analysis step. A new slow-fast extension of the popular Lorenz-96 model is introduced to demonstrate the properties of the proposed mollified ensemble Kalman filter.
Ensemble teleportation under suboptimal conditions
The possibility of teleportation is certainly the most interesting consequence of quantum non-separability. In the present paper, the feasibility of teleportation is examined on the basis of the rigorous ensemble interpretation of quantum mechanics if non-ideal constraints are imposed on the teleportation scheme. Importance is attached both to the case of noisy Einstein-Podolsky-Rosen (EPR) ensembles and to the conditions under which automatic teleportation is still possible. The success of teleportation is discussed using a new fidelity measure which avoids the weaknesses of previous proposals
Pattern classification using ensemble methods
Rokach, Lior
2009-01-01
Researchers from various disciplines such as pattern recognition, statistics, and machine learning have explored the use of ensemble methodology since the late seventies. Thus, they are faced with a wide variety of methods, given the growing interest in the field. This book aims to impose a degree of order upon this diversity by presenting a coherent and unified repository of ensemble methods, theories, trends, challenges and applications. The book describes in detail the classical methods, as well as the extensions and novel approaches developed recently. Along with algorithmic descriptions o
The Ensembl Variant Effect Predictor.
McLaren, William; Gil, Laurent; Hunt, Sarah E; Riat, Harpreet Singh; Ritchie, Graham R S; Thormann, Anja; Flicek, Paul; Cunningham, Fiona
2016-01-01
The Ensembl Variant Effect Predictor is a powerful toolset for the analysis, annotation, and prioritization of genomic variants in coding and non-coding regions. It provides access to an extensive collection of genomic annotation, with a variety of interfaces to suit different requirements, and simple options for configuring and extending analysis. It is open source, free to use, and supports full reproducibility of results. The Ensembl Variant Effect Predictor can simplify and accelerate variant interpretation in a wide range of study designs. PMID:27268795
Ensemble and constrained clustering with applications
Abdala, D.D. (Daniel)
2011-01-01
Diese Arbeit stellt neue Entwicklungen in Ensemble und Constrained Clustering vor und enthält die folgenden wesentlichen Beiträge: 1) Eine Vereinigung von Constrained und Ensemble Clustering in einem einheitlichen Framework. 2) Eine neue Methode zur Messung und Visualisierung der Variabilität von Ensembles. 3) Ein neues, Random Walker basiertes Verfahren für Ensemble Clustering. 4) Anwendung von Ensemble Clustering für Bildsegmentierung. 5) Eine neue Consensus-Funktion für das Ensemble Cluste...
Mise au point de deux nouveaux matériaux à base de cobalt
CEA
2014-01-01
Des chercheurs du CEA, du CNRS, du Collège de France et de l’Université de Grenoble ont mis au point deux nouveaux matériaux à base de cobalt capables de remplacer le platine, métal rare et cher, dans la production d’hydrogène à partir d’eau (électrolyse). L’un peut fonctionner en solution aqueuse de pH neutre. Le second constitue le premier matériau catalytique « commutable » et sans métaux nobles jamais créé capable d’intervenir dans les deux réactions chimiques essentielles à l’électrolys...
Tuberculose multirésistante chez l'enfant: à propos de deux cas
Slimani, Hajar; Bricha, Myriem; Sqalli, Fatima-Ezzahra; Hammi, Sanaa; Bourkadi, Jamal-Eddine
2016-01-01
La tuberculose multirésistante chez l'enfant est une forme grave de la tuberculose, présentant un problème majeur de santé surtout dans les pays en voie de développement. Nous présentons le cas de deux enfants suivis dans notre formation pour tuberculose multirésistante mis sous schéma thérapeutique de deuxième ligne. PMID:27279953
Note sur deux espèces de Lepidocyclina des Indes Néerlandaises
Schlumberger, C.
1899-01-01
Je dois à l’obligeance de Monsieur K. MARTIN professeur de Géologie à l’Université de Leiden l’envoi pour ma collection de foraminifères de quelques doubles des roches rapportées de Java par Monsieur VERBEEK et j’ai eu la bonne fortune d’y rencontrer deux espèces d’Orbitoïdes du sous-genre Lepidocyc
Tuberculose multirésistante chez l'enfant: à propos de deux cas
Slimani, Hajar; Bricha, Myriem; Sqalli, Fatima-Ezzahra; Sanaa HAMMI; Bourkadi, Jamal-Eddine
2016-01-01
La tuberculose multirésistante chez l'enfant est une forme grave de la tuberculose, présentant un problème majeur de santé surtout dans les pays en voie de développement. Nous présentons le cas de deux enfants suivis dans notre formation pour tuberculose multirésistante mis sous schéma thérapeutique de deuxième ligne.
Realisation de composants tout-fibre passifs bases sur des fibres optiques a deux coeurs
Jacob Poulin, Anne C.
2002-01-01
Les composants passifs tout-optique sont des elements de choix dans les systemes de communications optiques. Cette these presente l'utilisation experimentale de fibres a deux coeurs dissimilaires pour la realisation de filtres passe-bande. Les fibres a deux coeurs ont la particularite de favoriser un couplage d'un coeur a l'autre a intervalles reguliers lorsque les coeurs sont exactement identiques. Dans le cas ou une legere difference apparait, ce couplage est rapidement reduit a zero. La premiere partie de la these montre comment, par l'emploi d'une geometrie de fibre appropriee, il est possible de compenser cette desyntonisation et de fabriquer des coupleurs 100%. Les filtres obtenus ayant toutefois une largeur de bande trop grande pour les besoins du marche des communications optiques, il est montre dans la deuxieme partie de la these comment, en alliant la technologie des reseaux de Bragg avec celle des coupleurs, il est possible de realiser des filtres operant en transmission et possedant d'excellentes caracteristiques spectrales, toujours avec ces memes fibres a deux coeurs.
Multimodel ensembles of wheat growth
Martre, Pierre; Wallach, Daniel; Asseng, Senthold;
2015-01-01
such studies are difficult to organize and have only recently begun. We report on the largest ensemble study to date, of 27 wheat models tested in four contrasting locations for their accuracy in simulating multiple crop growth and yield variables. The relative error averaged over models was 24–38% for...
Ensemble algorithms in reinforcement learning
Wiering, Marco A; van Hasselt, Hado
2008-01-01
This paper describes several ensemble methods that combine multiple different reinforcement learning (RL) algorithms in a single agent. The aim is to enhance learning speed and final performance by combining the chosen actions or action probabilities of different RL algorithms. We designed and imple
Spectral Diagonal Ensemble Kalman Filters
Kasanický, Ivan; Mandel, Jan; Vejmelka, Martin
2015-01-01
Roč. 22, č. 4 (2015), s. 485-497. ISSN 1023-5809 R&D Projects: GA ČR GA13-34856S Grant ostatní: NSF(US) DMS -1216481 Institutional support: RVO:67985807 Keywords : data assimilation * ensemble Kalman filter * spectral representation Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.987, year: 2014
Spectral Diagonal Ensemble Kalman Filters
Kasanický, Ivan; Mandel, Jan; Vejmelka, Martin
2015-01-01
Roč. 22, č. 4 (2015), s. 485-497. ISSN 1023-5809 R&D Projects: GA ČR GA13-34856S Grant ostatní: NSF(US) DMS-1216481 Institutional support: RVO:67985807 Keywords : data assimilation * ensemble Kalman filter * spectral representation Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.987, year: 2014
Global Ensemble Forecast System (GEFS) [1 Deg.
National Oceanic and Atmospheric Administration, Department of Commerce — The Global Ensemble Forecast System (GEFS) is a weather forecast model made up of 21 separate forecasts, or ensemble members. The National Centers for Environmental...
Propriétés combinatoires des produits tensoriels d'ensembles convexes
Fonlupt, Jean
1981-01-01
Dans le premier chapitre on précise les définitions et notations utilisées par la suite et on rappelle certains résultats nécessaires ultérieurement. Dans le deuxième chapitre on définit à partir de deux ensembles convexes K1 et K2, le produit tensoriel direct note K1 cercle X K2 et polaire K1 d'Alemb. K2. Au troisième chapitre on étudie quelques propriétés faciales de K1 cercle x K2 et de K1d'alemb. K2. Au quatrième chapitre on étudie la relation entre K1 cercle X K2 et K1d'Alemb. K2. Enfin ...
Spectral diagonal ensemble Kalman filters
Kasanický, Ivan; Vejmelka, Martin
2015-01-01
A new type of ensemble Kalman filter is developed, which is based on replacing the sample covariance in the analysis step by its diagonal in a spectral basis. It is proved that this technique improves the aproximation of the covariance when the covariance itself is diagonal in the spectral basis, as is the case, e.g., for a second-order stationary random field and the Fourier basis. The method is extended by wavelets to the case when the state variables are random fields, which are not spatially homogeneous. Efficient implementations by the fast Fourier transform (FFT) and discrete wavelet transform (DWT) are presented for several types of observations, including high-dimensional data given on a part of the domain, such as radar and satellite images. Computational experiments confirm that the method performs well on the Lorenz 96 problem and the shallow water equations with very small ensembles and over multiple analysis cycles.
Spectral diagonal ensemble Kalman filters
I. Kasanický
2015-01-01
Full Text Available A new type of ensemble Kalman filter is developed, which is based on replacing the sample covariance in the analysis step by its diagonal in a spectral basis. It is proved that this technique improves the aproximation of the covariance when the covariance itself is diagonal in the spectral basis, as is the case, e.g., for a second-order stationary random field and the Fourier basis. The method is extended by wavelets to the case when the state variables are random fields which are not spatially homogeneous. Efficient implementations by the fast Fourier transform (FFT and discrete wavelet transform (DWT are presented for several types of observations, including high-dimensional data given on a part of the domain, such as radar and satellite images. Computational experiments confirm that the method performs well on the Lorenz 96 problem and the shallow water equations with very small ensembles and over multiple analysis cycles.
Symanzik flow on HISQ ensembles
Bazavov, A; Brown, N; DeTar, C; Foley, J; Gottlieb, Steven; Heller, U M; Hetrick, J E; Laiho, J; Levkova, L; Oktay, M; Sugar, R L; Toussaint, D; Van de Water, R S; Zhou, R
2013-01-01
We report on a scale determination with gradient-flow techniques on the $N_f = 2 + 1 + 1$ HISQ ensembles generated by the MILC collaboration. The lattice scale $w_0/a$, originally proposed by the BMW collaboration, is computed using Symanzik flow at four lattice spacings ranging from 0.15 to 0.06 fm. With a Taylor series ansatz, the results are simultaneously extrapolated to the continuum and interpolated to physical quark masses. We give a preliminary determination of the scale $w_0$ in physical units, along with associated systematic errors, and compare with results from other groups. We also present a first estimate of autocorrelation lengths as a function of flowtime for these ensembles.
Triticeae resources in Ensembl Plants.
Bolser, Dan M; Kerhornou, Arnaud; Walts, Brandon; Kersey, Paul
2015-01-01
Recent developments in DNA sequencing have enabled the large and complex genomes of many crop species to be determined for the first time, even those previously intractable due to their polyploid nature. Indeed, over the course of the last 2 years, the genome sequences of several commercially important cereals, notably barley and bread wheat, have become available, as well as those of related wild species. While still incomplete, comparison with other, more completely assembled species suggests that coverage of genic regions is likely to be high. Ensembl Plants (http://plants.ensembl.org) is an integrative resource organizing, analyzing and visualizing genome-scale information for important crop and model plants. Available data include reference genome sequence, variant loci, gene models and functional annotation. For variant loci, individual and population genotypes, linkage information and, where available, phenotypic information are shown. Comparative analyses are performed on DNA and protein sequence alignments. The resulting genome alignments and gene trees, representing the implied evolutionary history of the gene family, are made available for visualization and analysis. Driven by the case of bread wheat, specific extensions to the analysis pipelines and web interface have recently been developed to support polyploid genomes. Data in Ensembl Plants is accessible through a genome browser incorporating various specialist interfaces for different data types, and through a variety of additional methods for programmatic access and data mining. These interfaces are consistent with those offered through the Ensembl interface for the genomes of non-plant species, including those of plant pathogens, pests and pollinators, facilitating the study of the plant in its environment. PMID:25432969
State Ensembles and Quantum Entropy
Kak, Subhash
2016-06-01
This paper considers quantum communication involving an ensemble of states. Apart from the von Neumann entropy, it considers other measures one of which may be useful in obtaining information about an unknown pure state and another that may be useful in quantum games. It is shown that under certain conditions in a two-party quantum game, the receiver of the states can increase the entropy by adding another pure state.
Simple Deep Random Model Ensemble
ZHANG, XIAO-LEI; Wu, Ji
2013-01-01
Representation learning and unsupervised learning are two central topics of machine learning and signal processing. Deep learning is one of the most effective unsupervised representation learning approach. The main contributions of this paper to the topics are as follows. (i) We propose to view the representative deep learning approaches as special cases of the knowledge reuse framework of clustering ensemble. (ii) We propose to view sparse coding when used as a feature encoder as the consens...
Ensemble learning incorporating uncertain registration.
Simpson, Ivor J A; Woolrich, Mark W; Andersson, Jesper L R; Groves, Adrian R; Schnabel, Julia A
2013-04-01
This paper proposes a novel approach for improving the accuracy of statistical prediction methods in spatially normalized analysis. This is achieved by incorporating registration uncertainty into an ensemble learning scheme. A probabilistic registration method is used to estimate a distribution of probable mappings between subject and atlas space. This allows the estimation of the distribution of spatially normalized feature data, e.g., grey matter probability maps. From this distribution, samples are drawn for use as training examples. This allows the creation of multiple predictors, which are subsequently combined using an ensemble learning approach. Furthermore, extra testing samples can be generated to measure the uncertainty of prediction. This is applied to separating subjects with Alzheimer's disease from normal controls using a linear support vector machine on a region of interest in magnetic resonance images of the brain. We show that our proposed method leads to an improvement in discrimination using voxel-based morphometry and deformation tensor-based morphometry over bootstrap aggregating, a common ensemble learning framework. The proposed approach also generates more reasonable soft-classification predictions than bootstrap aggregating. We expect that this approach could be applied to other statistical prediction tasks where registration is important. PMID:23288332
Optimisation de la fonction MLI d’un onduleur de tension deux-niveaux
Capitaneanu, Stephan Laurentiu
2002-01-01
La fonction MLI (Modulation en Largeur d'Impulsion) ou PWM (Pulse Width Modulation) joue le rôle d'interface entre la partie commande d’un variateur de vitesse et la machine électrique associée. Cette fonction agit sur l'onduleur de tension (ou de courant) de la partie puissance du variateur et joue un rôle essentiel avec des conséquences sur toutes les performances du système. Nos travaux prennent en compte la machine asynchrone commandée à travers l'onduleur de tension deux-niveaux. Plusieu...
Comment attirer deux ravageurs des framboises dans un même piège?
Baroffio, Catherine; Borg-Karlson, Anna-Karin; Cross, Jerry; Fountain, Michelle; Guibert, Virginie; Hall, David; Ralle, Baiba; Rogivue, Aude; Sigsgaard, Lene; Trandem, Nina; Wibe, Atle
2015-01-01
L’anthonome des framboises (Anthonomus rubi) et le ver des framboises (Byturus tomentosus) causent de grosses pertes dans les cultures biologiques de framboises. Dans le cadre du projet européen Core Organic 2, le projet «Softpest Multitrap» a testé une nouvelle approche pour controller simultanément ces deux ravageurs avec un piège commun, afin de proposer une alternative aux insecticides. Le but a été de définir la hauteur du piège, son design et lacombinaison de leurres optimale. Nos essai...
Modélisation et simulation des usagers deux roues motorisés dans ARCHISIM
Bonte, L; ESPIE, S; Mathieu, P.
2006-01-01
Le but de ce travail est de proposer une approche permettant la simulation des usagers de deux-roues motorisés dans un modèle de trafic existant : ARCHISIM. ARCHISIM est un projet de l'INRETS qui a pour but de simuler l'évolution du trafic comme étant le résultat des différents comportements des acteurs de la simulation. Nous montrerons les différences avec les autres usagers de la route (automobilistes, piétons) et pourquoi ces comportements ne sont pas applicables, dans le cadre d'ARCHISIM,...
Territorialisation et circulation des échanges sociaux dans deux sites de la banlieue parisienne
Benveniste, Annie
2000-01-01
L'article analyse la construction de nouvelles territorialités en liaison avec le développement des mouvements ethno-religieux. Deux sites ont été choisis qui avaient fait l'objet d'une recherche sur la ségrégation résidentielle : Sarcelles et Garges-les-Gonesse. L'analyse porte d'abord sur les transformations des espaces, leur appropriation et la recombinaison du public et du privé qui permet de s'émanciper des contraintes de la relégation. Elle porte ensuite sur les nouvelles formes de soli...
Optimally choosing small ensemble members to produce robust climate simulations
This study examines the subset climate model ensemble size required to reproduce certain statistical characteristics from a full ensemble. The ensemble characteristics examined are the root mean square error, the ensemble mean and standard deviation. Subset ensembles are created using measures that consider the simulation performance alone or include a measure of simulation independence relative to other ensemble members. It is found that the independence measure is able to identify smaller subset ensembles that retain the desired full ensemble characteristics than either of the performance based measures. It is suggested that model independence be considered when choosing ensemble subsets or creating new ensembles. (letter)
TOLEDO Ma Del Mar
1993-07-01
Full Text Available Une première caractérisation des truites de mer des rivières du Nord de l'Espagne (Asturies est réalisée à partir de l'analyse de la structure de taille et d'âge, ainsi que celle de l'alimentation et des paramètres reproducteurs des poissons adultes. Les truites proviennent des captures réalisées à la ligne (de juin à août sur les rivières Cares et Narcea et par pêche électrique sur les zones de frayères du Narcea durant la saison de reproduction (novembre à janvier. Les truites de mer échantillonnées durant la saison de pêche ont une structure d'âge semblable sur les deux cours d'eau. Environ 85% des individus sont restés deux ans en eau douce avant de descendre en mer, et plus de 95% d'entre eux appartiennent aux classes d'âge de mer 0 + et 1 + . L'importance relative des poissons de 0 + de mer (finnock est légèrement plus élevée dans le Cares (68% que dans le Narcea (51 %. Le rapport des sexes est en faveur des femelles, quelle que soit la classe d'âge de mer. La structure d'âge marin des truites capturées en période de reproduction ne diffère pas de celle observée durant la saison de pêche, bien que montrant une haute proportion de 0 + de mer (32% de l'ensemble des poissons matures. Le taux de maturation chez les truites de 0 + de mer est particulièrement élevé ( 81% parmi les femelles et 100% chez les mâles et tous les individus des autres classes d'âge de mer sont matures. Le nombre d'oeufs (de 571 à 2086 oeufs par femelle et l'index gonadosomatique sont positivement corrélés à la taille et à l'âge de mer des femelles. La truite de mer se nourrit activement en eau douce durant la remontée estivale, puisque 81 % des estomacs examinés étaient pleins. Elle consomme principalement des Epheméroptères, des Diptères et des Trichoptères, mais son alimentation inclut également des proies d'origine terrestre, essentiellement des Arthropodes.
Measuring social interaction in music ensembles.
Volpe, Gualtiero; D'Ausilio, Alessandro; Badino, Leonardo; Camurri, Antonio; Fadiga, Luciano
2016-05-01
Music ensembles are an ideal test-bed for quantitative analysis of social interaction. Music is an inherently social activity, and music ensembles offer a broad variety of scenarios which are particularly suitable for investigation. Small ensembles, such as string quartets, are deemed a significant example of self-managed teams, where all musicians contribute equally to a task. In bigger ensembles, such as orchestras, the relationship between a leader (the conductor) and a group of followers (the musicians) clearly emerges. This paper presents an overview of recent research on social interaction in music ensembles with a particular focus on (i) studies from cognitive neuroscience; and (ii) studies adopting a computational approach for carrying out automatic quantitative analysis of ensemble music performances. PMID:27069054
Ensemble Methods Foundations and Algorithms
Zhou, Zhi-Hua
2012-01-01
An up-to-date, self-contained introduction to a state-of-the-art machine learning approach, Ensemble Methods: Foundations and Algorithms shows how these accurate methods are used in real-world tasks. It gives you the necessary groundwork to carry out further research in this evolving field. After presenting background and terminology, the book covers the main algorithms and theories, including Boosting, Bagging, Random Forest, averaging and voting schemes, the Stacking method, mixture of experts, and diversity measures. It also discusses multiclass extension, noise tolerance, error-ambiguity a
A Localized Ensemble Kalman Smoother
Butala, Mark D.
2012-01-01
Numerous geophysical inverse problems prove difficult because the available measurements are indirectly related to the underlying unknown dynamic state and the physics governing the system may involve imperfect models or unobserved parameters. Data assimilation addresses these difficulties by combining the measurements and physical knowledge. The main challenge in such problems usually involves their high dimensionality and the standard statistical methods prove computationally intractable. This paper develops and addresses the theoretical convergence of a new high-dimensional Monte-Carlo approach called the localized ensemble Kalman smoother.
A Selective Fuzzy Clustering Ensemble Algorithm
Kai Li; Peng Li
2013-01-01
To improve the performance of clustering ensemble method, a selective fuzzy clustering ensemble algorithm is proposed. It mainly includes selection of clustering ensemble members and combination of clustering results. In the process of member selection, measure method is defined to select the better clustering members. Then some selected clustering members are viewed as hyper-graph in order to select the more influential hyper-edges (or features) and to weight the selected features. For proce...
Controllability of ensembles of linear dynamical systems
Schönlein, Michael; Helmke, Uwe
2015-01-01
We investigate the task of controlling ensembles of initial and terminal state vectors of parameter-dependent linear systems by applying parameter-independent open loop controls. Necessary, as well as sufficient, conditions for ensemble controllability are established, using tools from complex approximation theory. For real analytic families of linear systems it is shown that ensemble controllability holds only for systems with at most two independent parameters. We apply the results to netwo...
A Gaussian mixture ensemble transform filter
Reich, Sebastian
2011-01-01
We generalize the popular ensemble Kalman filter to an ensemble transform filter where the prior distribution can take the form of a Gaussian mixture or a Gaussian kernel density estimator. The design of the filter is based on a continuous formulation of the Bayesian filter analysis step. We call the new filter algorithm the ensemble Gaussian mixture filter (EGMF). The EGMF is implemented for three simple test problems (Brownian dynamics in one dimension, Langevin dynamics in two dimensions, ...
Mamoudou, Savadogo; Bellaud, Guillaume; Ana, Canestri; Gilles, Pialoux
2015-01-01
Rapporter deux cas cliniques de coinfections pulmonaires par Pneumocystis jirovecii et par Pseudomonas aeruginosa chez des patients vivant avec le VIH. Les deux patients étaient âgés respectivement de 32 ans et 46 ans. Un patient a été pris en charge à l'hôpital Yalgado Ouédraogo de Ouagadougou au Burkina Faso et l'autre a été pris en charge à l'hôpital Ténon de Paris, en France. Les deux souffraient de pneumopathie confirmée à la radiographie et à la tomodensitométrie. L'un des patients étai...
Multi-Model Ensemble Wake Vortex Prediction
Koerner, Stephan; Holzaepfel, Frank; Ahmad, Nash'at N.
2015-01-01
Several multi-model ensemble methods are investigated for predicting wake vortex transport and decay. This study is a joint effort between National Aeronautics and Space Administration and Deutsches Zentrum fuer Luft- und Raumfahrt to develop a multi-model ensemble capability using their wake models. An overview of different multi-model ensemble methods and their feasibility for wake applications is presented. The methods include Reliability Ensemble Averaging, Bayesian Model Averaging, and Monte Carlo Simulations. The methodologies are evaluated using data from wake vortex field experiments.
Visualizing ensembles in structural biology.
Melvin, Ryan L; Salsbury, Freddie R
2016-06-01
Displaying a single representative conformation of a biopolymer rather than an ensemble of states mistakenly conveys a static nature rather than the actual dynamic personality of biopolymers. However, there are few apparent options due to the fixed nature of print media. Here we suggest a standardized methodology for visually indicating the distribution width, standard deviation and uncertainty of ensembles of states with little loss of the visual simplicity of displaying a single representative conformation. Of particular note is that the visualization method employed clearly distinguishes between isotropic and anisotropic motion of polymer subunits. We also apply this method to ligand binding, suggesting a way to indicate the expected error in many high throughput docking programs when visualizing the structural spread of the output. We provide several examples in the context of nucleic acids and proteins with particular insights gained via this method. Such examples include investigating a therapeutic polymer of FdUMP (5-fluoro-2-deoxyuridine-5-O-monophosphate) - a topoisomerase-1 (Top1), apoptosis-inducing poison - and nucleotide-binding proteins responsible for ATP hydrolysis from Bacillus subtilis. We also discuss how these methods can be extended to any macromolecular data set with an underlying distribution, including experimental data such as NMR structures. PMID:27179343
Hierarchical Bayes Ensemble Kalman Filtering
Tsyrulnikov, Michael
2015-01-01
Ensemble Kalman filtering (EnKF), when applied to high-dimensional systems, suffers from an inevitably small affordable ensemble size, which results in poor estimates of the background error covariance matrix ${\\bf B}$. The common remedy is a kind of regularization, usually an ad-hoc spatial covariance localization (tapering) combined with artificial covariance inflation. Instead of using an ad-hoc regularization, we adopt the idea by Myrseth and Omre (2010) and explicitly admit that the ${\\bf B}$ matrix is unknown and random and estimate it along with the state (${\\bf x}$) in an optimal hierarchical Bayes analysis scheme. We separate forecast errors into predictability errors (i.e. forecast errors due to uncertainties in the initial data) and model errors (forecast errors due to imperfections in the forecast model) and include the two respective components ${\\bf P}$ and ${\\bf Q}$ of the ${\\bf B}$ matrix into the extended control vector $({\\bf x},{\\bf P},{\\bf Q})$. Similarly, we break the traditional backgrou...
Faire territoire au quotidien dans les grands ensembles HLM
Denis la Mache
2012-05-01
Full Text Available Cet article propose une lecture anthropologique de la manière dont les habitants des grands ensembles de périphéries urbaines délimitent, administrent, transforment matériellement et symboliquement les espaces et les lieux de leur quotidien pour faire territoire. Nous nous intéresserons à la fabrication de ces entités spatiales dont chaque individu se donne la liberté de disposer chaque jour selon un usage singulier et qu’il entoure d’un champ symbolique spécifique, garant d’identité. Ces « fabrications sociospatiales » seront abordées à partir d’une recherche empirique menée auprès d’habitants de deux terrains d’enquêtes situés dans des périphéries de villes moyennes.This paper proposes an anthropological reading of how the inhabitants of large urban peripheries define, administer, and process their daily spaces and places from a material as much as symbolical point of view to give sense to their territory. We will focus on the making of these spatial entities, witch everyone can dispose of everyday individually, to guarantee their identity. These “socio spatial creations” will be based on an empirical research, that is to say surveys conducted among the suburbians of two towns.
Joys of Community Ensemble Playing: The Case of the Happy Roll Elastic Ensemble in Taiwan
Hsieh, Yuan-Mei; Kao, Kai-Chi
2012-01-01
The Happy Roll Elastic Ensemble (HREE) is a community music ensemble supported by Tainan Culture Centre in Taiwan. With enjoyment and friendship as its primary goals, it aims to facilitate the joys of ensemble playing and the spirit of social networking. This article highlights the key aspects of HREE's development in its first two years…
Comment le monde contemporain adapte les deux mythes fondateurs de l’humanité ?
Georges Lewi
2014-12-01
Full Text Available L’être humain, « un roseau, le plus faible de la nature, mais un roseau pensant », a besoin de trouver sa place dans une quête quasi maladive. Le petit être humain a autant besoin d’une boussole que d’un biberon. Voilà à quoi servent les mythes : à trouver enfin sa place parmi les oppositions binaires qui nous assaillent : dedans/dehors, montagne/vallée, homme/femme, mort/vivant, dominant/dominé, Artiste/artisan… Or dans cette géographie de l’intime social, deux mythes s’opposent depuis la nuit des temps : celui de l’âge d’or, mythe collectif du retour en arrière et celui de Pandore, mythe individuel de la fuite en avant. Notre société et nos contemporains n’échappent pas à cette « fatalité ».
Simulation numérique du bruit de frottement lors du contact de deux surfaces rugueuses
Dang, Viet Hung; Le Bot, Alain
2010-01-01
Le bruit généré lors du frottement de deux surfaces rugueuses l'une contre l'autre révèle des régimes et des propriétés très étonnantes [1]. Cependant les expérimentations [2], bien que fondamentales, ne donnent pas accès aux grandeurs mécaniques locales comme les chocs inter-aspérités, les déformations, et pressions locales Cette étude propose une approche numérique avec un modèle 1D basé sur la résolution des équations mécaniques par la technique de décomposition modale. Le traitement des ...
Variations discursives dans deux situations contrastées de la presse ordinaire
Moirand, Sophie
2009-01-01
Cette étude vise à comparer deux discours sur la science : l’un, mis au jour à partir d’un corpus constitué d’articles référant au domaine de l’astronomie, renvoie à la situation prototypique de la vulgarisation scientifique, dans laquelle le médiateur tient son rôle de gestionnaire discursif entre l’univers de la science et celui du public ; l’autre, mis au jour à partir d’un corpus constitué d’articles publiés à propos de la maladie de la vache folle et des organismes génétiquement modifiés...
Regards actuels sur la muséographie d’entre-deux-guerres
François Poncelet
2008-10-01
Full Text Available Durant l’entre-deux-guerres, la muséographie des musées d’art présente des évolutions remarquables. De nouvelles pratiques de mise en exposition sont élaborées, se développent et, pour certaines, perdurent jusqu’à aujourd’hui. Les débats dont elles sont issues ressemblent parfois singulièrement aux discussions qui animent les musées d’art actuels. Un regard en arrière s’impose …During the interwar period a remarkable evolution has been in museography of art galleries. New practices are elaborated, developed and continued for a long time – actually up to now for some. The debates in which they originated sometimes strangely resemble the discussions that animate the museums today. A look to back is necessary…
Les manuels scolaires bulgares au xxe siècle entre deux empires
Deyanova, Liliana
2015-01-01
Sur la base de l’étude de quelques types de manuels scolaires d’histoire, je me propose d’analyser les métamorphoses du récit concernant les deux empires qui ont eu un rôle clé dans l’histoire de la Bulgarie : l’Empire ottoman et l’Empire russe. Dans la mémoire nationale bulgare, les cinq siècles de « domination ottomane » («le joug turc »), dont le pays a été libéré à l’aide de la Russie en 1878, représentent l’archétype du malheur national : cruautés, massacres, villages incendiés, conversi...
Elections présidentielles 2007, typologie des candidats. Les deux France
Michel Bussi
2007-04-01
Full Text Available Depuis près de 25 ans, la géographie électorale de la France a été en grande partie marquée par la forte spatialisation du vote Front national, qui coupait en deux, d’Est en Ouest, le territoire national. Cependant, si cette « lune brune » s’est avérée durable de 1988 à 2007, les autres candidats apparaissaient jusqu’à présent indifférents à ce clivage géographique. L’un des enseignements de ce scrutin semble l’élargissement de ce clivage Est/Ouest à d’autres courants, en particulier à l’...
Layered Ensemble Architecture for Time Series Forecasting.
Rahman, Md Mustafizur; Islam, Md Monirul; Murase, Kazuyuki; Yao, Xin
2016-01-01
Time series forecasting (TSF) has been widely used in many application areas such as science, engineering, and finance. The phenomena generating time series are usually unknown and information available for forecasting is only limited to the past values of the series. It is, therefore, necessary to use an appropriate number of past values, termed lag, for forecasting. This paper proposes a layered ensemble architecture (LEA) for TSF problems. Our LEA consists of two layers, each of which uses an ensemble of multilayer perceptron (MLP) networks. While the first ensemble layer tries to find an appropriate lag, the second ensemble layer employs the obtained lag for forecasting. Unlike most previous work on TSF, the proposed architecture considers both accuracy and diversity of the individual networks in constructing an ensemble. LEA trains different networks in the ensemble by using different training sets with an aim of maintaining diversity among the networks. However, it uses the appropriate lag and combines the best trained networks to construct the ensemble. This indicates LEAs emphasis on accuracy of the networks. The proposed architecture has been tested extensively on time series data of neural network (NN)3 and NN5 competitions. It has also been tested on several standard benchmark time series data. In terms of forecasting accuracy, our experimental results have revealed clearly that LEA is better than other ensemble and nonensemble methods. PMID:25751882
A Selective Fuzzy Clustering Ensemble Algorithm
Kai Li
2013-12-01
Full Text Available To improve the performance of clustering ensemble method, a selective fuzzy clustering ensemble algorithm is proposed. It mainly includes selection of clustering ensemble members and combination of clustering results. In the process of member selection, measure method is defined to select the better clustering members. Then some selected clustering members are viewed as hyper-graph in order to select the more influential hyper-edges (or features and to weight the selected features. For processing hyper-edges with fuzzy membership, CSPA and MCLA consensus function are generalized. In the experiments, some UCI data sets are chosen to test the presented algorithm’s performance. From the experimental results, it can be seen that the proposed ensemble method can get better clustering ensemble result.
Rydberg ensemble based CNOTN gates using STIRAP
Gujarati, Tanvi; Duan, Luming
2016-05-01
Schemes for implementation of CNOT gates in atomic ensembles are important for realization of quantum computing. We present here a theoretical scheme of a CNOTN gate with an ensemble of three-level atoms in the lambda configuration and a single two-level control atom. We work in the regime of Rydberg blockade for the ensemble atoms due to excitation of the Rydberg control atom. It is shown that using STIRAP, atoms from one ground state of the ensemble can be adiabatically transferred to the other ground state, depending on the state of the control atom. A thorough analysis of adiabatic conditions for this scheme and the influence of the radiative decay is provided. We show that the CNOTN process is immune to the decay rate of the excited level in ensemble atoms. This work is supported by the ARL, the IARPA LogiQ program, and the AFOSR MURI program.
Bouallegue, Zied Ben; Theis, Susanne E; Pinson, Pierre
2015-01-01
Probabilistic forecasts in the form of ensemble of scenarios are required for complex decision making processes. Ensemble forecasting systems provide such products but the spatio-temporal structures of the forecast uncertainty is lost when statistical calibration of the ensemble forecasts is applied for each lead time and location independently. Non-parametric approaches allow the reconstruction of spatio-temporal joint probability distributions at a low computational cost.For example, the ensemble copula coupling (ECC) method consists in rebuilding the multivariate aspect of the forecast from the original ensemble forecasts. Based on the assumption of error stationarity, parametric methods aim to fully describe the forecast dependence structures. In this study, the concept of ECC is combined with past data statistics in order to account for the autocorrelation of the forecast error. The new approach which preserves the dynamical development of the ensemble members is called dynamic ensemble copula coupling (...
ENCORE: Software for Quantitative Ensemble Comparison.
Matteo Tiberti
2015-10-01
Full Text Available There is increasing evidence that protein dynamics and conformational changes can play an important role in modulating biological function. As a result, experimental and computational methods are being developed, often synergistically, to study the dynamical heterogeneity of a protein or other macromolecules in solution. Thus, methods such as molecular dynamics simulations or ensemble refinement approaches have provided conformational ensembles that can be used to understand protein function and biophysics. These developments have in turn created a need for algorithms and software that can be used to compare structural ensembles in the same way as the root-mean-square-deviation is often used to compare static structures. Although a few such approaches have been proposed, these can be difficult to implement efficiently, hindering a broader applications and further developments. Here, we present an easily accessible software toolkit, called ENCORE, which can be used to compare conformational ensembles generated either from simulations alone or synergistically with experiments. ENCORE implements three previously described methods for ensemble comparison, that each can be used to quantify the similarity between conformational ensembles by estimating the overlap between the probability distributions that underlie them. We demonstrate the kinds of insights that can be obtained by providing examples of three typical use-cases: comparing ensembles generated with different molecular force fields, assessing convergence in molecular simulations, and calculating differences and similarities in structural ensembles refined with various sources of experimental data. We also demonstrate efficient computational scaling for typical analyses, and robustness against both the size and sampling of the ensembles. ENCORE is freely available and extendable, integrates with the established MDAnalysis software package, reads ensemble data in many common formats, and can
Grigoraş, Cătălin; Mateescu, Theodor; Cherecheş, Nelu-Cristian
2011-01-01
Le but de ce travail est d’effectuer une nouvelle recherche dans le domaine du chauffage solaire passif et actif an étudiant le comportement thermodynamique de deux types de murs capteurs solaires et en même temps d’essayer d’encourager l’étude et la construction de maisons qui utilisent l’énergie solaire.
Mamoudou, Savadogo; Bellaud, Guillaume; Ana, Canestri; Gilles, Pialoux
2015-01-01
Rapporter deux cas cliniques de coinfections pulmonaires par Pneumocystis jirovecii et par Pseudomonas aeruginosa chez des patients vivant avec le VIH. Les deux patients étaient âgés respectivement de 32 ans et 46 ans. Un patient a été pris en charge à l'hôpital Yalgado Ouédraogo de Ouagadougou au Burkina Faso et l'autre a été pris en charge à l'hôpital Ténon de Paris, en France. Les deux souffraient de pneumopathie confirmée à la radiographie et à la tomodensitométrie. L'un des patients était sévèrement immuno déprimé, contrairement à l'autre. L'examen bactériologique dans les crachats avait permis d'isoler Pseudomonas aeruginosa et Pneumocystis jirovecii chez les deux patients. Sous traitement, l’évolution a été favorable. Les coinfections morbides sont relativement fréquentes chez les patients vivant avec le VIH. Devant une symptomatologie respiratoire du sujet vivant avec le VIH, il faut savoir rechercher en plus du Bacille de Koch, Pneumocystis jirovecii et Pseudomonas aeruginosa par un lavage broncho alvéolaire. PMID:26516396
Approximation et précision : deux facettes d'une même réalité
Asnes Maria
2014-07-01
Full Text Available L'approximation et la précision semblent être à deux pôles opposés: en effet, l'approximation est souvent considérée comme l'imprécision étant donné qu'elle fournit une représentation inexacte d'une valeur connue ou inconnue. Pourtant, la langue nous confronte avec des cas où le même terme peut avoir un sens tantôt approximatif tantôt précis. S'agit-il alors de deux emplois complètement distincts ou de deux effets de sens issus du même noyau sémantique? Cette étude prend comme objet l'adverbe plutôt qui manifeste des emplois approximatifs ainsi que précis.. A travers l'étude de ce terme on montrera que l'approximation et la précision ne sont pas toujours des termes opposés, mais qu'ils relèvent de deux facettes d'une même réalité de base.
Monuments épigraphiques de l’ensemble de Fatḥâbâd à Boukhara1
Babadžanov, Bahtijar
2010-01-01
L’ensemble de Fatḥâbâd est situé à un kilomètre à l’ouest environ de la forteresse extérieure de Boukhara. Son apparition est liée à l’activité d’Abû’l-Ma‘âlî Sa‘îd b. al-Muṭahhar, célèbre cheikh kubravî, plus connu sous le nom Sayf al-Dîn al-Bâkharzî al-Bukhârî. Son action, ainsi que le fonctionnement de cet ensemble ont été déjà étudiés en détail dans plusieurs ouvrages. De nos jours l’ensemble architectural comprend la khânaqâh et la tombe de Sayf al-Dîn Bâkharzî, le mausolée de deux pièce...
Nonequilibrium representative ensembles for isolated quantum systems
An isolated quantum system is considered, prepared in a nonequilibrium initial state. In order to uniquely define the system dynamics, one has to construct a representative statistical ensemble. From the principle of least action it follows that the role of the evolution generator is played by a grand Hamiltonian, but not merely by its energy part. A theorem is proved expressing the commutators of field operators with operator products through variational derivatives of these products. A consequence of this theorem is the equivalence of the variational equations for field operators with the Heisenberg equations for the latter. A finite quantum system cannot equilibrate in the strict sense. But it can tend to a quasi-stationary state characterized by ergodic averages and the appropriate representative ensemble depending on initial conditions. Microcanonical ensemble, arising in the eigenstate thermalization, is just a particular case of representative ensembles. Quasi-stationary representative ensembles are defined by the principle of minimal information. The latter also implies the minimization of an effective thermodynamic potential. -- Highlights: → The evolution of a nonequilibrium isolated quantum system is considered. → The grand Hamiltonian is shown to be the evolution generator. → A theorem is proved connecting operator commutators with variational derivatives. → Quasi-stationary states are described by representative ensembles. → These ensembles, generally, depend on initial conditions.
Hybrid Data Assimilation without Ensemble Filtering
Todling, Ricardo; Akkraoui, Amal El
2014-01-01
The Global Modeling and Assimilation Office is preparing to upgrade its three-dimensional variational system to a hybrid approach in which the ensemble is generated using a square-root ensemble Kalman filter (EnKF) and the variational problem is solved using the Grid-point Statistical Interpolation system. As in most EnKF applications, we found it necessary to employ a combination of multiplicative and additive inflations, to compensate for sampling and modeling errors, respectively and, to maintain the small-member ensemble solution close to the variational solution; we also found it necessary to re-center the members of the ensemble about the variational analysis. During tuning of the filter we have found re-centering and additive inflation to play a considerably larger role than expected, particularly in a dual-resolution context when the variational analysis is ran at larger resolution than the ensemble. This led us to consider a hybrid strategy in which the members of the ensemble are generated by simply converting the variational analysis to the resolution of the ensemble and applying additive inflation, thus bypassing the EnKF. Comparisons of this, so-called, filter-free hybrid procedure with an EnKF-based hybrid procedure and a control non-hybrid, traditional, scheme show both hybrid strategies to provide equally significant improvement over the control; more interestingly, the filter-free procedure was found to give qualitatively similar results to the EnKF-based procedure.
Politiques agricoles et enjeux paysagers. Analyse sur deux territoires rhône-alpins
Dominique VOLLET
2007-01-01
Les paysages sont progressivement intégrés comme ressource potentielle de développement économique. Cette intégration se fait dans un ensemble de politiques sectorielles, y compris agricoles, pour des territoires présentant des caractéristiques et des stratégies de développement différenciées. Le niveau du territoire est-il en mesure de donner une certaine cohérence à cet ensemble hétérogène de politiques, notamment dans la façon d’y considérer le paysage ? Pour tenter de répondre à cette que...
Derivation of Mayer Series from Canonical Ensemble
Xian-Zhi, Wang
2016-02-01
Mayer derived the Mayer series from both the canonical ensemble and the grand canonical ensemble by use of the cluster expansion method. In 2002, we conjectured a recursion formula of the canonical partition function of a fluid (X.Z. Wang, Phys. Rev. E 66 (2002) 056102). In this paper we give a proof for this formula by developing an appropriate expansion of the integrand of the canonical partition function. We further derive the Mayer series solely from the canonical ensemble by use of this recursion formula.
Atomic clock ensemble in space
Atomic Clock Ensemble in Space (ACES) is a mission using high-performance clocks and links to test fundamental laws of physics in space. Operated in the microgravity environment of the International Space Station, the ACES clocks, PHARAO and SHM, will generate a frequency reference reaching instability and inaccuracy at the 1 · 10−16 level. A link in the microwave domain (MWL) and an optical link (ELT) will make the ACES clock signal available to ground laboratories equipped with atomic clocks. Space-to-ground and ground-to-ground comparisons of atomic frequency standards will be used to test Einstein's theory of general relativity including a precision measurement of the gravitational red-shift, a search for time variations of fundamental constants, and Lorentz Invariance tests. Applications in geodesy, optical time transfer, and ranging will also be supported. ACES has now reached an advanced technology maturity, with engineering models completed and successfully tested and flight hardware under development. This paper presents the ACES mission concept and the status of its main instruments.
Cooperative effects of neuronal ensembles.
Rose, G; Siebler, M
1995-01-01
Electrophysiological properties of neurons as the basic cellular elements of the central nervous system and their synaptic connections are well characterized down to a molecular level. However, the behavior of complex noisy networks formed by these constituents usually cannot simply be derived from the knowledge of its microscopic parameters. As a consequence, cooperative phenomena based on the interaction of neurons were postulated. This is a report on a study of global network spike activity as a function of synaptic interaction. We performed experiments in dissociated cultured hippocampal neurons and, for comparison, simulations of a mathematical model closely related to electrophysiology. Numeric analyses revealed that at a critical level of synaptic connectivity the firing behavior undergoes a phase transition. This cooperative effect depends crucially on the interaction of numerous cells and cannot be attributed to the spike threshold of individual neurons. In the experiment a drastic increase in the firing level was observed upon increase of synaptic efficacy by lowering of the extracellular magnesium concentration, which is compatible with our theoretical predictions. This "on-off" phenomenon demonstrates that even in small neuronal ensembles collective behavior can emerge which is not explained by the characteristics of single neurons. PMID:8542966
Ben Bouallègue, Zied; Heppelmann, Tobias; Theis, Susanne E.;
2015-01-01
is applied for each lead time and location independently. Non-parametric approaches allow the reconstruction of spatio-temporal joint probability distributions at a low computational cost.For example, the ensemble copula coupling (ECC) method consists in rebuilding the multivariate aspect of the forecast...... from the original ensemble forecasts. Based on the assumption of error stationarity, parametric methods aim to fully describe the forecast dependence structures. In this study, the concept of ECC is combined with past data statistics in order to account for the autocorrelation of the forecast error....... The new approach which preserves the dynamical development of the ensemble members is called dynamic ensemble copula coupling (d-ECC). The ensemble based empirical copulas, ECC and d-ECC, are applied to wind forecasts from the high resolution ensemble system COSMO-DEEPS run operationally at the German...
Transition from Poisson to circular unitary ensemble
Vinayak; Akhilesh Pandey
2009-09-01
Transitions to universality classes of random matrix ensembles have been useful in the study of weakly-broken symmetries in quantum chaotic systems. Transitions involving Poisson as the initial ensemble have been particularly interesting. The exact two-point correlation function was derived by one of the present authors for the Poisson to circular unitary ensemble (CUE) transition with uniform initial density. This is given in terms of a rescaled symmetry breaking parameter Λ. The same result was obtained for Poisson to Gaussian unitary ensemble (GUE) transition by Kunz and Shapiro, using the contour-integral method of Brezin and Hikami. We show that their method is applicable to Poisson to CUE transition with arbitrary initial density. Their method is also applicable to the more general ℓ CUE to CUE transition where CUE refers to the superposition of ℓ independent CUE spectra in arbitrary ratio.
Data assimilation the ensemble Kalman filter
Evensen, Geir
2006-01-01
Covers data assimilation and inverse methods, including both traditional state estimation and parameter estimation. This text and reference focuses on various popular data assimilation methods, such as weak and strong constraint variational methods and ensemble filters and smoothers.
Irreplaceability of Neuronal Ensembles after Memory Allocation
Naoki Matsuo
2015-04-01
Full Text Available Lesion studies suggest that an alternative system can compensate for damage to the primary region employed when animals acquire a memory. However, it is unclear whether functional compensation occurs at the cellular ensemble level. Here, we inhibited the activities of a specific subset of neurons activated during initial learning by utilizing a transgenic mouse that expresses tetanus toxin (TeNT under the control of the c-fos promoter. Notably, suppression interfered with relearning while sparing the ability to acquire and express fear memory for a distinct context. These results suggest that the activity of the initial ensemble is preferentially dedicated to the same learning and that it is not replaceable once it is allocated. Our results provide substantial insights into the machinery underlying how the brain allocates individual memories to discrete neuronal ensembles and how it ensures that repetitive learning strengthens memory by reactivating the same neuronal ensembles.
Ensemble Machine Learning Methods and Applications
Ma, Yunqian
2012-01-01
It is common wisdom that gathering a variety of views and inputs improves the process of decision making, and, indeed, underpins a democratic society. Dubbed “ensemble learning” by researchers in computational intelligence and machine learning, it is known to improve a decision system’s robustness and accuracy. Now, fresh developments are allowing researchers to unleash the power of ensemble learning in an increasing range of real-world applications. Ensemble learning algorithms such as “boosting” and “random forest” facilitate solutions to key computational issues such as face detection and are now being applied in areas as diverse as object trackingand bioinformatics. Responding to a shortage of literature dedicated to the topic, this volume offers comprehensive coverage of state-of-the-art ensemble learning techniques, including various contributions from researchers in leading industrial research labs. At once a solid theoretical study and a practical guide, the volume is a windfall for r...
DUPONT,A
2001-01-01
Au début du xX siècle se développe chez les économistes l'exigence d'un rapprochement de type nouveau entre la théorie et la réalité, rapprochement pensé dans la perspective de la mesure. L'économie quantitative s'élabore tout particulièrement à partir de 1910, autour de deux approches majeures.' l'empirisme et l'économétrie. Nous prendrons comme référent le champ de recherche du cycle des affaires pour comprendre et analyser les points communs et les divergences entre ces deux programmes, ca...
Orbital magnetism in ensembles of ballistic billiards
The magnetic response of ensembles of small two-dimensional structures at finite temperatures is calculated. Using semiclassical methods and numerical calculation it is demonstrated that only short classical trajectories are relevant. The magnetic susceptibility is enhanced in regular systems, where these trajectories appear in families. For ensembles of squares large paramagnetic susceptibility is obtained, in good agreement with recent measurements in the ballistic regime. (authors). 20 refs., 2 figs
Coherent ensemble averaging techniques for impedance cardiography
Hurwitz, Barry E.; Shyu, Liang-Yu; Reddy, Sridhar P; Schneiderman, Neil; Nagel, Joachim H.
1990-01-01
EKG synchronized ensemble averaging of the impedance cardiogram tends to blur or suppress signal events due to signal jitter or event latency variability. Although ensemble averaging provides some improvement in the stability of the signal and signal to noise ratio under conditions of nonperiodic influences of respiration and motion, coherent averaging techniques were developed to determine whether further enhancement of the impedance cardiogram could be obtained. Physiological signals were o...
Ensemble methods for noise in classification problems
Verbaeten, Sofie; Van Assche, Anneleen
2003-01-01
Ensemble methods combine a set of classifiers to construct a new classifier that is (often) more accurate than any of its component classifiers. In this paper, we use ensemble methods to identify noisy training examples. More precisely, we consider the problem of mislabeled training examples in classification tasks, and address this problem by pre-processing the training set, i.e. by identifying and removing outliers from the training set. We study a number of filter techniques that are based...
Calibrating ensemble reliability whilst preserving spatial structure
Jonathan Flowerdew
2014-03-01
Full Text Available Ensemble forecasts aim to improve decision-making by predicting a set of possible outcomes. Ideally, these would provide probabilities which are both sharp and reliable. In practice, the models, data assimilation and ensemble perturbation systems are all imperfect, leading to deficiencies in the predicted probabilities. This paper presents an ensemble post-processing scheme which directly targets local reliability, calibrating both climatology and ensemble dispersion in one coherent operation. It makes minimal assumptions about the underlying statistical distributions, aiming to extract as much information as possible from the original dynamic forecasts and support statistically awkward variables such as precipitation. The output is a set of ensemble members preserving the spatial, temporal and inter-variable structure from the raw forecasts, which should be beneficial to downstream applications such as hydrological models. The calibration is tested on three leading 15-d ensemble systems, and their aggregation into a simple multimodel ensemble. Results are presented for 12 h, 1° scale over Europe for a range of surface variables, including precipitation. The scheme is very effective at removing unreliability from the raw forecasts, whilst generally preserving or improving statistical resolution. In most cases, these benefits extend to the rarest events at each location within the 2-yr verification period. The reliability and resolution are generally equivalent or superior to those achieved using a Local Quantile-Quantile Transform, an established calibration method which generalises bias correction. The value of preserving spatial structure is demonstrated by the fact that 3×3 averages derived from grid-scale precipitation calibration perform almost as well as direct calibration at 3×3 scale, and much better than a similar test neglecting the spatial relationships. Some remaining issues are discussed regarding the finite size of the output
Controlling balance in an ensemble Kalman filter
G. A. Gottwald
2014-01-01
We present a method to control unbalanced fast dynamics in an ensemble Kalman filter by introducing a weak constraint on the imbalance in a spatially sparse observational network. We show that the balance constraint produces significantly more balanced analyses than ensemble Kalman filters without balance constraints and than filters implementing incremental analysis updates (IAU). Furthermore, our filter with the weak constraint on imbalance produces good rms error statisti...
Towards a GME ensemble forecasting system: Ensemble initialization using the breeding technique
Jan D. Keller
2008-12-01
Full Text Available The quantitative forecast of precipitation requires a probabilistic background particularly with regard to forecast lead times of more than 3 days. As only ensemble simulations can provide useful information of the underlying probability density function, we built a new ensemble forecasting system (GME-EFS based on the GME model of the German Meteorological Service (DWD. For the generation of appropriate initial ensemble perturbations we chose the breeding technique developed by Toth and Kalnay (1993, 1997, which develops perturbations by estimating the regions of largest model error induced uncertainty. This method is applied and tested in the framework of quasi-operational forecasts for a three month period in 2007. The performance of the resulting ensemble forecasts are compared to the operational ensemble prediction systems ECMWF EPS and NCEP GFS by means of ensemble spread of free atmosphere parameters (geopotential and temperature and ensemble skill of precipitation forecasting. This comparison indicates that the GME ensemble forecasting system (GME-EFS provides reasonable forecasts with spread skill score comparable to that of the NCEP GFS. An analysis with the continuous ranked probability score exhibits a lack of resolution for the GME forecasts compared to the operational ensembles. However, with significant enhancements during the 3 month test period, the first results of our work with the GME-EFS indicate possibilities for further development as well as the potential for later operational usage.
Passeport pour les deux infinis vers l'infiniment grand, vers l'infiniment petit
Arnaud, Nicolas; Kerhoas-Cavata, Sophie; Paul, Jacques; Robert-Esil, Jean-Luc; Royole-Degieux, Perrine
2013-01-01
Où commence l'infiniment grand ? Où finit l'infiniment petit ? Les chercheurs ont identifié le rayonnement fossile émis il y a 13,7 milliards d'année et qui permet de remonter aux origines de l'Univers. A l'opposé, le modèle standard a identifié 12 particules élémentaires et trois forces fondamentales qui permettent de décrire la constitution ultime de la matière. Est-ce à dire que tout est terminé, que plus rien n'est à découvrir ? Certainement pas ! Tandis que les outils d'observation deviennent plus précis, la nécessité d'établir des passerelles entre l'infiniment grand et l'infini petit devient pressante. Dans ce livre illustré en couleur, les plus grands spécialistes présentent un panorama des connaissances actuelles pour voyager à la découverte des deux infinis. Cette nouvelle édition à jour tient compte des derniers réusultats du LHC dans sa quête du fameux boson de Higgs, et intègre les premières images du rayonnement fossile provenant du satellite Planck.
Meaning of temperature in different thermostatistical ensembles.
Hänggi, Peter; Hilbert, Stefan; Dunkel, Jörn
2016-03-28
Depending on the exact experimental conditions, the thermodynamic properties of physical systems can be related to one or more thermostatistical ensembles. Here, we survey the notion of thermodynamic temperature in different statistical ensembles, focusing in particular on subtleties that arise when ensembles become non-equivalent. The 'mother' of all ensembles, the microcanonical ensemble, uses entropy and internal energy (the most fundamental, dynamically conserved quantity) to derive temperature as a secondary thermodynamic variable. Over the past century, some confusion has been caused by the fact that several competing microcanonical entropy definitions are used in the literature, most commonly the volume and surface entropies introduced by Gibbs. It can be proved, however, that only the volume entropy satisfies exactly the traditional form of the laws of thermodynamics for a broad class of physical systems, including all standard classical Hamiltonian systems, regardless of their size. This mathematically rigorous fact implies that negative 'absolute' temperatures and Carnot efficiencies more than 1 are not achievable within a standard thermodynamical framework. As an important offspring of microcanonical thermostatistics, we shall briefly consider the canonical ensemble and comment on the validity of the Boltzmann weight factor. We conclude by addressing open mathematical problems that arise for systems with discrete energy spectra. PMID:26903095
Conductor gestures influence evaluations of ensemble performance.
Morrison, Steven J; Price, Harry E; Smedley, Eric M; Meals, Cory D
2014-01-01
Previous research has found that listener evaluations of ensemble performances vary depending on the expressivity of the conductor's gestures, even when performances are otherwise identical. It was the purpose of the present study to test whether this effect of visual information was evident in the evaluation of specific aspects of ensemble performance: articulation and dynamics. We constructed a set of 32 music performances that combined auditory and visual information and were designed to feature a high degree of contrast along one of two target characteristics: articulation and dynamics. We paired each of four music excerpts recorded by a chamber ensemble in both a high- and low-contrast condition with video of four conductors demonstrating high- and low-contrast gesture specifically appropriate to either articulation or dynamics. Using one of two equivalent test forms, college music majors and non-majors (N = 285) viewed sixteen 30 s performances and evaluated the quality of the ensemble's articulation, dynamics, technique, and tempo along with overall expressivity. Results showed significantly higher evaluations for performances featuring high rather than low conducting expressivity regardless of the ensemble's performance quality. Evaluations for both articulation and dynamics were strongly and positively correlated with evaluations of overall ensemble expressivity. PMID:25104944
Heinrich Heine et Annette von Droste-Hülshoff Deux poètes d ‘Allemagne
Kortländer, Bernd
2011-01-01
L’article tente un rapprochement entre deux poètes que l’on a peu l’habitude de nommer à la suite l’un de l’autre, Heinrich Heine et Annette von Droste-Hülshoff. Cette comparaison de deux figures majeures de la poésie allemande du Vormärz permet de faire ressortir, à travers leur dissemblance radicale, les spécificités de chacune. Du point de vue de l’œuvre même les différences sautent d’emblée aux yeux. A la musicalité et à l’élégance de Heine s’oppose du côté de Droste une langue qui renonc...
L’analyse du discours et ses entre-deux : notes sur son histoire au Brésil
Puccinelli Orlandi, Eni
2014-01-01
À Paul Henry pour l’excellence théorique avec laquelle, dès le début, il a exploré la force et les nuances de l’analyse du discours. Introduction Mettant hors du champ de la réflexion discursive la notion d’« intervalle », je propose une pratique matérialiste de l’analyse du discours par son inscription dans un espace d’« entre-deux », jusqu’au sein même de l’histoire des théories linguistiques. À la différence de celle d’intervalle, l’idée d’entre-deux renvoie à des espaces simultanément hab...
Ensemble postprocessing for probabilistic quantitative precipitation forecasts
Bentzien, S.; Friederichs, P.
2012-12-01
Precipitation is one of the most difficult weather variables to predict in hydrometeorological applications. In order to assess the uncertainty inherent in deterministic numerical weather prediction (NWP), meteorological services around the globe develop ensemble prediction systems (EPS) based on high-resolution NWP systems. With non-hydrostatic model dynamics and without parameterization of deep moist convection, high-resolution NWP models are able to describe convective processes in more detail and provide more realistic mesoscale structures. However, precipitation forecasts are still affected by displacement errors, systematic biases and fast error growth on small scales. Probabilistic guidance can be achieved from an ensemble setup which accounts for model error and uncertainty of initial and boundary conditions. The German Meteorological Service (Deutscher Wetterdienst, DWD) provides such an ensemble system based on the German-focused limited-area model COSMO-DE. With a horizontal grid-spacing of 2.8 km, COSMO-DE is the convection-permitting high-resolution part of the operational model chain at DWD. The COSMO-DE-EPS consists of 20 realizations of COSMO-DE, driven by initial and boundary conditions derived from 4 global models and 5 perturbations of model physics. Ensemble systems like COSMO-DE-EPS are often limited with respect to ensemble size due to the immense computational costs. As a consequence, they can be biased and exhibit insufficient ensemble spread, and probabilistic forecasts may be not well calibrated. In this study, probabilistic quantitative precipitation forecasts are derived from COSMO-DE-EPS and evaluated at more than 1000 rain gauges located all over Germany. COSMO-DE-EPS is a frequently updated ensemble system, initialized 8 times a day. We use the time-lagged approach to inexpensively increase ensemble spread, which results in more reliable forecasts especially for extreme precipitation events. Moreover, we will show that statistical
A Unification of Ensemble Square Root Kalman Filters
Nerger, Lars; Janjic Pfander, Tijana; Schröter, Jens; Hiller, Wolfgang
2012-01-01
In recent years, several ensemble-based Kalman filter algorithms have been developed that have been classified as ensemble square-root Kalman filters. Parallel to this development, the SEIK (Singular ``Evolutive'' Interpolated Kalman) filter has been introduced and applied in several studies. Some publications note that the SEIK filter is an ensemble Kalman filter or even an ensemble square-root Kalman filter. This study examines the relation of the SEIK filter to ensemble square-root filters...
On the Convergence of the Ensemble Kalman Filter
Mandel, Jan; Cobb, Loren; Beezley, Jonathan D.
2009-01-01
Convergence of the ensemble Kalman filter in the limit for large ensembles to the Kalman filter is proved. In each step of the filter, convergence of the ensemble sample covariance follows from a weak law of large numbers for exchangeable random variables, the continuous mapping theorem gives convergence in probability of the ensemble members, and $L^p$ bounds on the ensemble then give $L^p$ convergence.
A multisite seasonal ensemble streamflow forecasting technique
Bracken, Cameron; Rajagopalan, Balaji; Prairie, James
2010-03-01
We present a technique for providing seasonal ensemble streamflow forecasts at several locations simultaneously on a river network. The framework is an integration of two recent approaches: the nonparametric multimodel ensemble forecast technique and the nonparametric space-time disaggregation technique. The four main components of the proposed framework are as follows: (1) an index gauge streamflow is constructed as the sum of flows at all the desired spatial locations; (2) potential predictors of the spring season (April-July) streamflow at this index gauge are identified from the large-scale ocean-atmosphere-land system, including snow water equivalent; (3) the multimodel ensemble forecast approach is used to generate the ensemble flow forecast at the index gauge; and (4) the ensembles are disaggregated using a nonparametric space-time disaggregation technique resulting in forecast ensembles at the desired locations and for all the months within the season. We demonstrate the utility of this technique in skillful forecast of spring seasonal streamflows at four locations in the Upper Colorado River Basin at different lead times. Where applicable, we compare the forecasts to the Colorado Basin River Forecast Center's Ensemble Streamflow Prediction (ESP) and the National Resource Conservation Service "coordinated" forecast, which is a combination of the ESP, Statistical Water Supply, a principal component regression technique, and modeler knowledge. We find that overall, the proposed method is equally skillful to existing operational models while tending to better predict wet years. The forecasts from this approach can be a valuable input for efficient planning and management of water resources in the basin.
Haberman, Jason; Brady, Timothy F; Alvarez, George A
2015-04-01
Ensemble perception, including the ability to "see the average" from a group of items, operates in numerous feature domains (size, orientation, speed, facial expression, etc.). Although the ubiquity of ensemble representations is well established, the large-scale cognitive architecture of this process remains poorly defined. We address this using an individual differences approach. In a series of experiments, observers saw groups of objects and reported either a single item from the group or the average of the entire group. High-level ensemble representations (e.g., average facial expression) showed complete independence from low-level ensemble representations (e.g., average orientation). In contrast, low-level ensemble representations (e.g., orientation and color) were correlated with each other, but not with high-level ensemble representations (e.g., facial expression and person identity). These results suggest that there is not a single domain-general ensemble mechanism, and that the relationship among various ensemble representations depends on how proximal they are in representational space. PMID:25844624
Folie a deux: a case report [v1; ref status: indexed, http://f1000r.es/SD4pSL
Sobia Haqqi
2012-09-01
Full Text Available Folie a deux, to date, remains a rare, yet a challenging psychiatric diagnosis. We discuss two cases that were identified in our out-patient clinics. One case was lost to follow up, while the other one showed improvement over time with appropriate management. Conclusion: As with any rare disorder, recognition and correct referral for rare diagnosis like folie a deux is of paramount importance.
Deux modèles de fondation dans les Recherches logiques
Thomas Nenon
2009-02-01
Full Text Available Cette étude essaye d’établir qu’il y a deux notions très différentes de « fondation » à l’œuvre dans les Recherches logiques de Husserl. Dans la IIIème Recherche, où le terme est formellement introduit, lorsqu’il se demande quels sont les contenus qui peuvent exister d’une manière autonome (indépendants et lesquels peuvent exister uniquement en tant que moments d’autre chose (dépendants, Husserl suit ce que j’appelle un « modèle ontologique ». Selon ce modèle, le concret possède une priorité sur à l’abstrait qui est fondé en lui. Dans la VIème Recherche, en revanche, Husserl s’oriente principalement sur un « modèle gnoséologique » qui voit le complexe comme fondé sur ce qui est relativement simple, étant donné que les expériences d’ordre supérieur (telles les perceptions de types d’objets plus complexes sont « fondées sur » des expériences plus simples, bien qu’elles ne puissent pas y être réduites. L’exemple principal ici est celui des intuitions catégoriales : fondées sur les intuitions sensibles, elles n’y sont pas réductibles. Mais cette distinction entre deux sens différents du terme de « fondation » peut également nous aider à mieux comprendre de nombreuses thèses husserliennes plutôt controversées. Par exemple, elle peut nous permettre de mieux comprendre dans quelle mesure faire l’expérience d’un être humain comme un tout se fonde sur l’expérience d’un corps physique, et cela même si l’étant que nous rencontrons inclut à la fois des aspects corporels et des aspects spirituels – les deux étant vus, d’une manière essentielle, comme des moments de cette unique personne qui fait l’objet de notre expérience.This essay attempts to establish that there are two very different notions of “foundation” at work in Husserl’s Logical Investigation. In the Third Investigation where the term is formally introduced, Husserl is using what
Simulations in generalized ensembles through noninstantaneous switches
Giovannelli, Edoardo; Cardini, Gianni; Chelli, Riccardo
2015-10-01
Generalized-ensemble simulations, such as replica exchange and serial generalized-ensemble methods, are powerful simulation tools to enhance sampling of free energy landscapes in systems with high energy barriers. In these methods, sampling is enhanced through instantaneous transitions of replicas, i.e., copies of the system, between different ensembles characterized by some control parameter associated with thermodynamical variables (e.g., temperature or pressure) or collective mechanical variables (e.g., interatomic distances or torsional angles). An interesting evolution of these methodologies has been proposed by replacing the conventional instantaneous (trial) switches of replicas with noninstantaneous switches, realized by varying the control parameter in a finite time and accepting the final replica configuration with a Metropolis-like criterion based on the Crooks nonequilibrium work (CNW) theorem. Here we revise these techniques focusing on their correlation with the CNW theorem in the framework of Markovian processes. An outcome of this report is the derivation of the acceptance probability for noninstantaneous switches in serial generalized-ensemble simulations, where we show that explicit knowledge of the time dependence of the weight factors entering such simulations is not necessary. A generalized relationship of the CNW theorem is also provided in terms of the underlying equilibrium probability distribution at a fixed control parameter. Illustrative calculations on a toy model are performed with serial generalized-ensemble simulations, especially focusing on the different behavior of instantaneous and noninstantaneous replica transition schemes.
The Hydrologic Ensemble Prediction Experiment (HEPEX)
Wood, A. W.; Thielen, J.; Pappenberger, F.; Schaake, J. C.; Hartman, R. K.
2012-12-01
The Hydrologic Ensemble Prediction Experiment was established in March, 2004, at a workshop hosted by the European Center for Medium Range Weather Forecasting (ECMWF). With support from the US National Weather Service (NWS) and the European Commission (EC), the HEPEX goal was to bring the international hydrological and meteorological communities together to advance the understanding and adoption of hydrological ensemble forecasts for decision support in emergency management and water resources sectors. The strategy to meet this goal includes meetings that connect the user, forecast producer and research communities to exchange ideas, data and methods; the coordination of experiments to address specific challenges; and the formation of testbeds to facilitate shared experimentation. HEPEX has organized about a dozen international workshops, as well as sessions at scientific meetings (including AMS, AGU and EGU) and special issues of scientific journals where workshop results have been published. Today, the HEPEX mission is to demonstrate the added value of hydrological ensemble prediction systems (HEPS) for emergency management and water resources sectors to make decisions that have important consequences for economy, public health, safety, and the environment. HEPEX is now organised around six major themes that represent core elements of a hydrologic ensemble prediction enterprise: input and pre-processing, ensemble techniques, data assimilation, post-processing, verification, and communication and use in decision making. This poster presents an overview of recent and planned HEPEX activities, highlighting case studies that exemplify the focus and objectives of HEPEX.
Ensemble habitat mapping of invasive plant species
Stohlgren, T.J.; Ma, P.; Kumar, S.; Rocca, M.; Morisette, J.T.; Jarnevich, C.S.; Benson, N.
2010-01-01
Ensemble species distribution models combine the strengths of several species environmental matching models, while minimizing the weakness of any one model. Ensemble models may be particularly useful in risk analysis of recently arrived, harmful invasive species because species may not yet have spread to all suitable habitats, leaving species-environment relationships difficult to determine. We tested five individual models (logistic regression, boosted regression trees, random forest, multivariate adaptive regression splines (MARS), and maximum entropy model or Maxent) and ensemble modeling for selected nonnative plant species in Yellowstone and Grand Teton National Parks, Wyoming; Sequoia and Kings Canyon National Parks, California, and areas of interior Alaska. The models are based on field data provided by the park staffs, combined with topographic, climatic, and vegetation predictors derived from satellite data. For the four invasive plant species tested, ensemble models were the only models that ranked in the top three models for both field validation and test data. Ensemble models may be more robust than individual species-environment matching models for risk analysis. ?? 2010 Society for Risk Analysis.
Ensemble approach for differentiation of malignant melanoma
Rastgoo, Mojdeh; Morel, Olivier; Marzani, Franck; Garcia, Rafael
2015-04-01
Melanoma is the deadliest type of skin cancer, yet it is the most treatable kind depending on its early diagnosis. The early prognosis of melanoma is a challenging task for both clinicians and dermatologists. Due to the importance of early diagnosis and in order to assist the dermatologists, we propose an automated framework based on ensemble learning methods and dermoscopy images to differentiate melanoma from dysplastic and benign lesions. The evaluation of our framework on the recent and public dermoscopy benchmark (PH2 dataset) indicates the potential of proposed method. Our evaluation, using only global features, revealed that ensembles such as random forest perform better than single learner. Using random forest ensemble and combination of color and texture features, our framework achieved the highest sensitivity of 94% and specificity of 92%.
Clustering-based selective neural network ensemble
FU Qiang; HU Shang-xu; ZHAO Sheng-ying
2005-01-01
An effective ensemble should consist of a set of networks that are both accurate and diverse. We propose a novel clustering-based selective algorithm for constructing neural network ensemble, where clustering technology is used to classify trained networks according to similarity and optimally select the most accurate individual network from each cluster to make up the ensemble. Empirical studies on regression of four typical datasets showed that this approach yields significantly smaller en semble achieving better performance than other traditional ones such as Bagging and Boosting. The bias variance decomposition of the predictive error shows that the success of the proposed approach may lie in its properly tuning the bias/variance trade-offto reduce the prediction error (the sum of bias2 and variance).
Luminescence simulations of ensembles of silicon nanocrystals
Lockwood, Ross; Meldrum, Al [Department of Physics, University of Alberta, Edmonton (Canada)
2009-05-15
The luminescence of silicon nanocrystals (NCs) has attracted a great deal of interest due to the numerous potential photonic applications of light-emitting silicon. However, the excitation mechanisms and cluster-cluster interactions in densely-packed ensembles, as well as the recombination processes that influence the emission spectrum and lifetime are not yet well understood. In order to generate a more complete picture of the controlling parameters in the luminescence, a dynamic Monte Carlo model that incorporates several key physical processes for luminescent nanocrystal ensembles is developed. The model simulates Forster-type multipole energy transfer, tunnelling interactions, radiative decay and non-radiative trapping in physically realistic (lognormal) distributions of silicon NCs. The results of the simulation illustrate the effects of the NC size distribution, homogeneous and inhomogeneous broadening, NC packing density, and non-radiative trapping on the ensemble luminescence spectrum. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Matrix averages relating to Ginibre ensembles
Forrester, Peter J [Department of Mathematics and Statistics, University of Melbourne, Victoria 3010 (Australia); Rains, Eric M [Department of Mathematics, California Institute of Technology, Pasadena, CA 91125 (United States)], E-mail: p.forrester@ms.unimelb.edu.au
2009-09-25
The theory of zonal polynomials is used to compute the average of a Schur polynomial of argument AX, where A is a fixed matrix and X is from the real Ginibre ensemble. This generalizes a recent result of Sommers and Khoruzhenko (2009 J. Phys. A: Math. Theor. 42 222002), and furthermore allows analogous results to be obtained for the complex and real quaternion Ginibre ensembles. As applications, the positive integer moments of the general variance Ginibre ensembles are computed in terms of generalized hypergeometric functions; these are written in terms of averages over matrices of the same size as the moment to give duality formulas, and the averages of the power sums of the eigenvalues are expressed as finite sums of zonal polynomials.
Control and Synchronization of Neuron Ensembles
Li, Jr-Shin; Ruths, Justin
2011-01-01
Synchronization of oscillations is a phenomenon prevalent in natural, social, and engineering systems. Controlling synchronization of oscillating systems is motivated by a wide range of applications from neurological treatment of Parkinson's disease to the design of neurocomputers. In this article, we study the control of an ensemble of uncoupled neuron oscillators described by phase models. We examine controllability of such a neuron ensemble for various phase models and, furthermore, study the related optimal control problems. In particular, by employing Pontryagin's maximum principle, we analytically derive optimal controls for spiking single- and two-neuron systems, and analyze the applicability of the latter to an ensemble system. Finally, we present a robust computational method for optimal control of spiking neurons based on pseudospectral approximations. The methodology developed here is universal to the control of general nonlinear phase oscillators.
Embedded random matrix ensembles in quantum physics
Kota, V K B
2014-01-01
Although used with increasing frequency in many branches of physics, random matrix ensembles are not always sufficiently specific to account for important features of the physical system at hand. One refinement which retains the basic stochastic approach but allows for such features consists in the use of embedded ensembles. The present text is an exhaustive introduction to and survey of this important field. Starting with an easy-to-read introduction to general random matrix theory, the text then develops the necessary concepts from the beginning, accompanying the reader to the frontiers of present-day research. With some notable exceptions, to date these ensembles have primarily been applied in nuclear spectroscopy. A characteristic example is the use of a random two-body interaction in the framework of the nuclear shell model. Yet, topics in atomic physics, mesoscopic physics, quantum information science and statistical mechanics of isolated finite quantum systems can also be addressed using these ensemb...
Ensemble Kalman methods for inverse problems
The ensemble Kalman filter (EnKF) was introduced by Evensen in 1994 (Evensen 1994 J. Geophys. Res. 99 10143–62) as a novel method for data assimilation: state estimation for noisily observed time-dependent problems. Since that time it has had enormous impact in many application domains because of its robustness and ease of implementation, and numerical evidence of its accuracy. In this paper we propose the application of an iterative ensemble Kalman method for the solution of a wide class of inverse problems. In this context we show that the estimate of the unknown function that we obtain with the ensemble Kalman method lies in a subspace A spanned by the initial ensemble. Hence the resulting error may be bounded above by the error found from the best approximation in this subspace. We provide numerical experiments which compare the error incurred by the ensemble Kalman method for inverse problems with the error of the best approximation in A, and with variants on traditional least-squares approaches, restricted to the subspace A. In so doing we demonstrate that the ensemble Kalman method for inverse problems provides a derivative-free optimization method with comparable accuracy to that achieved by traditional least-squares approaches. Furthermore, we also demonstrate that the accuracy is of the same order of magnitude as that achieved by the best approximation. Three examples are used to demonstrate these assertions: inversion of a compact linear operator; inversion of piezometric head to determine hydraulic conductivity in a Darcy model of groundwater flow; and inversion of Eulerian velocity measurements at positive times to determine the initial condition in an incompressible fluid. (paper)
Native ultrametricity of sparse random ensembles
Avetisov, V.; Krapivsky, P. L.; Nechaev, S.
2016-01-01
We investigate the eigenvalue density in ensembles of large sparse Bernoulli random matrices. Analyzing in detail the spectral density of ensembles of linear subgraphs, we discuss its ultrametric nature and show that near the spectrum boundary, the tails of the spectral density exhibit a Lifshitz singularity typical for Anderson localization. We pay attention to an intriguing connection of the spectral density to the Dedekind η-function. We conjecture that ultrametricity emerges in rare-event statistics and is inherit to generic complex sparse systems.
Ensemble Enabled Weighted PageRank
Luo, Dongsheng; Hu, Renjun; Duan, Liang; Ma, Shuai
2016-01-01
This paper describes our solution for WSDM Cup 2016. Ranking the query independent importance of scholarly articles is a critical and challenging task, due to the heterogeneity and dynamism of entities involved. Our approach is called Ensemble enabled Weighted PageRank (EWPR). To do this, we first propose Time-Weighted PageRank that extends PageRank by introducing a time decaying factor. We then develop an ensemble method to assemble the authorities of the heterogeneous entities involved in scholarly articles. We finally propose to use external data sources to further improve the ranking accuracy. Our experimental study shows that our EWPR is a good choice for ranking scholarly articles.
Efficient inference of protein structural ensembles
Lane, Thomas J; Beauchamp, Kyle A; Pande, Vijay S
2014-01-01
It is becoming clear that traditional, single-structure models of proteins are insufficient for understanding their biological function. Here, we outline one method for inferring, from experiments, not only the most common structure a protein adopts (native state), but the entire ensemble of conformations the system can adopt. Such ensemble mod- els are necessary to understand intrinsically disordered proteins, enzyme catalysis, and signaling. We suggest that the most difficult aspect of generating such a model will be finding a small set of configurations to accurately model structural heterogeneity and present one way to overcome this challenge.
SEIK - the unknown ensemble Kalman filter
Nerger, Lars; Janjic Pfander, Tijana; Hiller, Wolfgang; Schröter, Jens
2009-01-01
The SEIK filter (Singular "Evolutive" Interpolated Kalman filter) hasbeen introduced in 1998 by D.T. Pham as a variant of the SEEK filter,which is a reduced-rank approximation of the Extended KalmanFilter. In recent years, it has been shown that the SEIK filter isan ensemble-based Kalman filter that uses a factorization rather thansquare-root of the state error covariance matrix. Unfortunately, theexistence of the SEIK filter as an ensemble-based Kalman filter withsimilar efficiency as the la...
Ensemble computing for the petroleum industry
Computer downsizing is one of the most often used buzzwords in today's competitive business, and the petroleum industry is at the forefront of this revolution. Ensemble computing provides the key for computer downsizing with its first incarnation, i.e., workstation farms. This paper concerns the importance of increasing the productivity cycle and not just the execution time of a job. The authors introduce the concept of ensemble computing and workstation farms. The they discuss how different computing paradigms can be addressed by workstation farms
Total probabilities of ensemble runoff forecasts
Olav Skøien, Jon; Bogner, Konrad; Salamon, Peter; Smith, Paul; Pappenberger, Florian
2016-04-01
Ensemble forecasting has for a long time been used as a method in meteorological modelling to indicate the uncertainty of the forecasts. However, as the ensembles often exhibit both bias and dispersion errors, it is necessary to calibrate and post-process them. Two of the most common methods for this are Bayesian Model Averaging (Raftery et al., 2005) and Ensemble Model Output Statistics (EMOS) (Gneiting et al., 2005). There are also methods for regionalizing these methods (Berrocal et al., 2007) and for incorporating the correlation between lead times (Hemri et al., 2013). Engeland and Steinsland Engeland and Steinsland (2014) developed a framework which can estimate post-processing parameters which are different in space and time, but still can give a spatially and temporally consistent output. However, their method is computationally complex for our larger number of stations, and cannot directly be regionalized in the way we would like, so we suggest a different path below. The target of our work is to create a mean forecast with uncertainty bounds for a large number of locations in the framework of the European Flood Awareness System (EFAS - http://www.efas.eu) We are therefore more interested in improving the forecast skill for high-flows rather than the forecast skill of lower runoff levels. EFAS uses a combination of ensemble forecasts and deterministic forecasts from different forecasters to force a distributed hydrologic model and to compute runoff ensembles for each river pixel within the model domain. Instead of showing the mean and the variability of each forecast ensemble individually, we will now post-process all model outputs to find a total probability, the post-processed mean and uncertainty of all ensembles. The post-processing parameters are first calibrated for each calibration location, but assuring that they have some spatial correlation, by adding a spatial penalty in the calibration process. This can in some cases have a slight negative
Analyse de la richesse piscicole de quatre ensembles hydrographiques français
PONT D.
1995-04-01
Full Text Available L'analyse des variations de richesse en espèces piscicoles autochtones le long des gradients longitudinaux de quatre ensembles hydrographiques français met en évidence un accroissement amont-aval similaire par type de bassins (grands bassins de la Seine et du Rhône et fleuves côtiers breton et du Languedoc-Roussillon. Les richesses spécifiques sont comparables à l'amont (0 à 4 km de la source et diffèrent significativement plus en aval. Dans les deux grands bassins, la pente est le premier facteur explicatif de la variation de la richesse en espèces autochtones, suivi de la distance à la source, de l'altitude et de la largeur. A une échelle d'espace supérieure, le positionnement géographique (latitude n'a pas d'effet significatif. Dans ces bassins, la richesse en espèces autochtones serait d'abord régulée par les conditions prévalant aux échelles locales et de la zonation.
Science, Linguistique, Littérature : trois disciplines, deux discours, une culture
Sandrine SORLIN
2010-09-01
Full Text Available Cet article propose une réflexion sur les frontières épistémologiques et méthodologiques qui séparent trois disciplines universitaires. Portées par un discours propre à l’économie de leur discipline, la littérature et la science se pensent l’une l’autre comme « deux cultures » antinomiques. Or chaque discipline aborde son objet d’étude à partir d’un paradigme qui est culturellement déterminé. La concomitance de l’apparition des « théories du chaos » en science et du mouvement postmoderne en littérature dans les années 70 par exemple s’explique par leur appartenance à une même culture qui, à un moment donné, a opéré un changement de paradigme informant toutes les disciplines. La linguistique n’y a pas échappé ; pourtant le problème de ses frontières demeure. Nous mettrons en avant la transversalité de cette discipline, laquelle permet - entre autres - de rendre compte non seulement d’un style littéraire mais aussi de ce qu’on peut appeler la « rhétorique » ou la textualité de la science.This paper aims at considering the methodological and epistemological boundaries separating three academic disciplines. Underlain by a discourse that is proper to the economy of their discipline, literature and science regard each other as two opposite cultures. Yet each tackles its object of study through a culturally-determined paradigm. The simultaneous birth of chaos theory in science and postmodern aestheticism in literature in the 70s for instance can only be accounted for if we think of them as belonging to the same culture, which, at some point, brought about a change in paradigm that informed all disciplines. Linguistics underwent the same process. Yet the question of its boundaries remains. We will see to what extent linguistics can be seen as cross-disciplinary, in its study of the rhetoric of both literary and scientific textuality.
Ensemble. Mobile Learning to Promote Social Inclusion
G. Bonaiuti; Ranieri, M.; P. Ravotto
2010-01-01
Final English Booklet of Ensemble project. Mobile learning, or m-learning, is the new term that is gaining ground in the educational technology vocabulary. The project has tried to find out how mobile devices could be integrated into learning settings to improve social inclusion.
Symplectic structure of the real Ginibre ensemble
Sommers, Hans-Juergen [Fachbereich Physik, Universitaet Duisburg-Essen, 47048 Duisburg (Germany)
2007-07-20
We give a simple derivation of all n-point densities for the eigenvalues of the real Ginibre ensemble with even dimension N as quaternion determinants. A very simple symplectic kernel governs both the real and complex correlations. One- and two-point correlations are discussed in more detail. Scaling forms for large dimension N are derived. (fast track communication)
Tiered Evaluation in Large Ensemble Settings.
Scott, David
1998-01-01
Discusses the use of a tiered evaluation system (TES) that allows students to work at different levels, enables teachers to assess progress objectively, and presents students with appropriate challenges in the music ensembles. Focuses on how TES works and its advantages, considers the challenges and flexibility of TES, and provides samples. (CMK)
Partition Function of Interacting Calorons Ensemble
Deldar, Sedigheh
2015-01-01
We present a method for computing the partition function of a caloron ensemble taking into account the interaction of calorons. We focus on caloron-Dirac string interaction and show that the metric that Diakonov and Petrov offered works well in the limit where this interaction occurs. We suggest computing the correlation function of two polyakov loops by applying Ewald's method.
Partition function of interacting calorons ensemble
Deldar, S.; Kiamari, M.
2016-01-01
We present a method for computing the partition function of a caloron ensemble taking into account the interaction of calorons. We focus on caloron-Dirac string interaction and show that the metric that Diakonov and Petrov offered, works well in the limit where this interaction occurs. We suggest computing the correlation function of two polyakov loops by applying Ewald's method.
NYYD Ensemble ja Riho Sibul / Anneli Remme
Remme, Anneli, 1968-
2001-01-01
Gavin Bryarsi teos "Jesus' Blood Never Failed Me Yet" NYYD Ensemble'i ja Riho Sibula esituses 27. detsembril Pauluse kirikus Tartus ja 28. detsembril Rootsi- Mihkli kirikus Tallinnas. Kaastegevad Tartu Ülikooli Kammerkoor (Tartus) ja kammerkoor Voces Musicales (Tallinnas). Kunstiline juht Olari Elts
Conductor gestures influence evaluations of ensemble performance
Steven eMorrison
2014-07-01
Full Text Available Previous research has found that listener evaluations of ensemble performances vary depending on the expressivity of the conductor’s gestures, even when performances are otherwise identical. It was the purpose of the present study to test whether this effect of visual information was evident in the evaluation of specific aspects of ensemble performance, articulation and dynamics. We constructed a set of 32 music performances that combined auditory and visual information and were designed to feature a high degree of contrast along one of two target characteristics: articulation and dynamics. We paired each of four music excerpts recorded by a chamber ensemble in both a high- and low-contrast condition with video of four conductors demonstrating high- and low-contrast gesture specifically appropriate to either articulation or dynamics. Using one of two equivalent test forms, college music majors and nonmajors (N = 285 viewed sixteen 30-second performances and evaluated the quality of the ensemble’s articulation, dynamics, technique and tempo along with overall expressivity. Results showed significantly higher evaluations for performances featuring high rather than low conducting expressivity regardless of the ensemble’s performance quality. Evaluations for both articulation and dynamics were strongly and positively correlated with evaluations of overall ensemble expressivity.
Embedded feature ranking for ensemble MLP classifiers
Windeatt, T; Duangsoithong, R; Smith, R
2011-01-01
A feature ranking scheme for multilayer perceptron (MLP) ensembles is proposed, along with a stopping criterion based upon the out-of-bootstrap estimate. To solve multi-class problems feature ranking is combined with modified error-correcting output coding. Experimental results on benchmark data demonstrate the versatility of the MLP base classifier in removing irrelevant features.
Ensemble Filtering in Air Quality Models
Eben, Kryštof; Juruš, Pavel; Resler, Jaroslav; Belda, M.; Pelikán, Emil
Brno : Masaryk University, 2007 - (Horová, I.; Hřebíček, J.) ISBN 978-80-210-4333-6. [ TIES 2007. Annual Meeting of the International Environmental Society /18./. 16.08.2007-20.08.2007, Mikulov] Institutional research plan: CEZ:AV0Z10300504 Keywords : air quality models * data assimilation * ensemble filtering
Lorentz-invariant ensembles of vector backgrounds
We consider gauge field theories in the presence of ensembles of vector backgrounds. While Lorentz invariance is explicitly broken in the presence of any single background, here, the Lorentz invariance of the theory is restored by averaging over a Lorentz-invariant ensemble of backgrounds, i.e., a set of background vectors that is mapped onto itself under Lorentz transformations. This framework is used to study the effects of a non-trivial but Lorentz-invariant vacuum structure or mass dimension two vector condensates by identifying the background with a shift of the gauge field. Up to now, the ensembles used in the literature comprise configurations corresponding to non-zero field tensors together with such with vanishing field strength. We find that even when constraining the ensembles to pure gauge configurations, the usual high-energy degrees of freedom are removed from the spectrum of asymptotic states in the presence of said backgrounds in Euclidean and in Minkowski space. We establish this result not only for the propagators to all orders in the background and otherwise at tree level but for the full propagator
The Hydrologic Ensemble Prediction Experiment (HEPEX)
Wood, Andy; Wetterhall, Fredrik; Ramos, Maria-Helena
2015-04-01
The Hydrologic Ensemble Prediction Experiment was established in March, 2004, at a workshop hosted by the European Center for Medium Range Weather Forecasting (ECMWF), and co-sponsored by the US National Weather Service (NWS) and the European Commission (EC). The HEPEX goal was to bring the international hydrological and meteorological communities together to advance the understanding and adoption of hydrological ensemble forecasts for decision support. HEPEX pursues this goal through research efforts and practical implementations involving six core elements of a hydrologic ensemble prediction enterprise: input and pre-processing, ensemble techniques, data assimilation, post-processing, verification, and communication and use in decision making. HEPEX has grown through meetings that connect the user, forecast producer and research communities to exchange ideas, data and methods; the coordination of experiments to address specific challenges; and the formation of testbeds to facilitate shared experimentation. In the last decade, HEPEX has organized over a dozen international workshops, as well as sessions at scientific meetings (including AMS, AGU and EGU) and special issues of scientific journals where workshop results have been published. Through these interactions and an active online blog (www.hepex.org), HEPEX has built a strong and active community of nearly 400 researchers & practitioners around the world. This poster presents an overview of recent and planned HEPEX activities, highlighting case studies that exemplify the focus and objectives of HEPEX.
Semi-classical approximation and microcanonical ensemble
For quantum mechanical systems with spherically symmetric potential the improved W.K.B. approximation of Elworthy and Truman corresponds to the classical microcanonical ensemble in the limit where (h/2π) goes to zero, at least for small time. (orig.)
Canonical Ensemble Model for Black Hole Radiation
Jingyi Zhang
2014-09-01
In this paper, a canonical ensemble model for the black hole quantum tunnelling radiation is introduced. In this model the probability distribution function corresponding to the emission shell is calculated to second order. The formula of pressure and internal energy of the thermal system is modified, and the fundamental equation of thermodynamics is also discussed.
Land Cover Mapping Using Ensemble Feature Selection Methods
Gidudu, A; Marwala, T
2008-01-01
Ensemble classification is an emerging approach to land cover mapping whereby the final classification output is a result of a consensus of classifiers. Intuitively, an ensemble system should consist of base classifiers which are diverse i.e. classifiers whose decision boundaries err differently. In this paper ensemble feature selection is used to impose diversity in ensembles. The features of the constituent base classifiers for each ensemble were created through an exhaustive search algorithm using different separability indices. For each ensemble, the classification accuracy was derived as well as a diversity measure purported to give a measure of the inensemble diversity. The correlation between ensemble classification accuracy and diversity measure was determined to establish the interplay between the two variables. From the findings of this paper, diversity measures as currently formulated do not provide an adequate means upon which to constitute ensembles for land cover mapping.
Space Applications for Ensemble Detection and Analysis Project
National Aeronautics and Space Administration — Ensemble Detection is both a measurement technique and analysis tool. Like a prism that separates light into spectral bands, an ensemble detector mixes a signal...
Ensemble-based Kalman Filters in Strongly Nonlinear Dynamics
Zhaoxia PU; Joshua HACKER
2009-01-01
This study examines the effectiveness of ensemble Kalman filters in data assimilation with the strongly nonlinear dynamics of the Lorenz-63 model, and in particular their use in predicting the regime transition that occurs when the model jumps from one basin of attraction to the other. Four configurations of the ensemble-based Kalman filtering data assimilation techniques, including the ensemble Kalman filter, ensemble adjustment Kalman filter, ensemble square root filter and ensemble transform Kalman filter, are evaluated with their ability in predicting the regime transition (also called phase transition) and also are compared in terms of their sensitivity to both observational and sampling errors. The sensitivity of each ensemble-based filter to the size of the ensemble is also examined.
Global Ensemble Forecast System (GEFS) [2.5 Deg.
National Oceanic and Atmospheric Administration, Department of Commerce — The Global Ensemble Forecast System (GEFS) is a weather forecast model made up of 21 separate forecasts, or ensemble members. The National Centers for Environmental...
Semaine d'Etude Mathématiques et Entreprises 1 : Deux problèmes sur les parcs solaires.
Aguillon, Nina; Benzekry, Sebastien; Bettinelli, Jérémie; Bochard, Pierre; Bonnotte, Nicolas; Delgado, Gabriel; Imbert-Gérard, Lise-Marie; Lepoultier, Guilhem; Navoret, Laurent; Parini, Enea
2011-01-01
Le premier problème consiste à étudier le placement quasi-optimal de parcs de panneaux solaires dans une région géographique définie. Si on suppose que la puissance d'un parc est directement proportionnelle à sa surface, on voudra maximiser la somme des surfaces des parcs. Néanmoins, la construction de tels parcs solaires est souvent soumise à des contraintes légales portant sur la puissance maximale de chaque parc et sur la distance entre deux parcs. Les idées proposées dans ce rapport tiend...
Dam, Denise Van; Nizet, Jean; Streith, Michel
2011-01-01
L’agriculture biologique en tant que nouveau mouvement social économique est parcourue par des tensions. Dans cet article nous posons l’hypothèse qu’elles font évoluer le mouvement vers l’institutionnalisation. Nous testons cette hypothèse en comparant deux événements promotionnels du bio en Alsace : la Foire Eco-Bio d’Alsace, créée en 1982 dans un contexte hostile au bio et le Salon BiObernai, créé en 2004 dans un contexte plus accueillant. Nous observons ces évolutions au travers du prisme ...
Sur la stabilite des Ondes Spheriques et le Mouvement d'un Fluide entre deux Plaques Infinies
Roussier-Michon, Violaine
2003-01-01
Cette thèse a pour objet le comportement asymptotique de solutions globales d'Equations aux Dérivées Partielles d'évolution paraboliques semilinéaires. A travers deux exemples distincts, on traite de la convergence en temps des solutions vers des solutions particulières (ondes progressives, solutions autosimilaires). Dans un premier temps, on étudie la stabilité asymptotique des ondes progressives à symétrie sphérique dans une équation de réaction-diffusion scalaire avec non-linéarité bistabl...
Mamoudou, Savadogo; Lassina, Dao; Fla, Koueta
2015-01-01
Nous rapportons deux cas d'infection à Pseudomonas aeruginosa: un cas de méningite et un cas d'infection urinaire. Les auteurs rappellent qu’à côté des étiologies classiques des méningites et des infections urinaires, des germes résistants comme Pseudomonas aeruginosa peuvent être responsables d'infections à localisation méningées et urinaires et dont il faut connaître pour une bonne prise en charge. Le traitement de ces infections requiert un antibiogramme au regard de la grande capacité de ...
Black Hole Statistical Mechanics and The Angular Velocity Ensemble
Thomson, Mitchell
2012-01-01
An new ensemble - the angular velocity ensemble - is derived using Jaynes' method of maximising entropy subject to prior information constraints. The relevance of the ensemble to black holes is motivated by a discussion of external parameters in statistical mechanics and their absence from the Hamiltonian of general relativity. It is shown how this leads to difficulty in deriving entropy as a function of state and recovering the first law of thermodynamics from the microcanonical and canonical ensembles applied to black holes.
Evaluation of an ensemble-based incremental variational data assimilation
Yang, Yin; Robinson, Cordelia; Heitz, Dominique; Mémin, Etienne
2014-01-01
In this work, we aim at studying ensemble based optimal control strategies for data assimilation. Such formulation nicely combines the ingredients of ensemble Kalman filters and variational data assimilation (4DVar). In the same way as variational assimilation schemes, it is formulated as the minimization of an objective function, but similarly to ensemble filter, it introduces in its objective function an empirical ensemble-based background-error covariance and works in an off-line smoothing...
Data assimilation in integrated hydrological modeling using ensemble Kalman filtering
Rasmussen, Jørn; Madsen, H.; Jensen, Karsten Høgh;
2015-01-01
Groundwater head and stream discharge is assimilated using the ensemble transform Kalman filter in an integrated hydrological model with the aim of studying the relationship between the filter performance and the ensemble size. In an attempt to reduce the required number of ensemble members, an...
A COMPREHENSIVE EVOLUTIONARY APPROACH FOR NEURAL NETWORK ENSEMBLES AUTOMATIC DESIGN
Bukhtoyarov, V.; Semenkin, E.
2010-01-01
A new comprehensive approach for neural network ensembles design is proposed. It consists of a method of neural networks automatic design and a method of automatic formation of an ensemble solution on the basis of separate neural networks solutions. It is demonstrated that the proposed approach is not less effective than a number of other approaches for neural network ensembles design.
Sampling Motif-Constrained Ensembles of Networks
Fischer, Rico; Leitão, Jorge C.; Peixoto, Tiago P.; Altmann, Eduardo G.
2015-10-01
The statistical significance of network properties is conditioned on null models which satisfy specified properties but that are otherwise random. Exponential random graph models are a principled theoretical framework to generate such constrained ensembles, but which often fail in practice, either due to model inconsistency or due to the impossibility to sample networks from them. These problems affect the important case of networks with prescribed clustering coefficient or number of small connected subgraphs (motifs). In this Letter we use the Wang-Landau method to obtain a multicanonical sampling that overcomes both these problems. We sample, in polynomial time, networks with arbitrary degree sequences from ensembles with imposed motifs counts. Applying this method to social networks, we investigate the relation between transitivity and homophily, and we quantify the correlation between different types of motifs, finding that single motifs can explain up to 60% of the variation of motif profiles.
Sampling motif-constrained ensembles of networks
Fischer, Rico; Peixoto, Tiago P; Altmann, Eduardo G
2015-01-01
The statistical significance of network properties is conditioned on null models which satisfy spec- ified properties but that are otherwise random. Exponential random graph models are a principled theoretical framework to generate such constrained ensembles, but which often fail in practice, either due to model inconsistency, or due to the impossibility to sample networks from them. These problems affect the important case of networks with prescribed clustering coefficient or number of small connected subgraphs (motifs). In this paper we use the Wang-Landau method to obtain a multicanonical sampling that overcomes both these problems. We sample, in polynomial time, net- works with arbitrary degree sequences from ensembles with imposed motifs counts. Applying this method to social networks, we investigate the relation between transitivity and homophily, and we quantify the correlation between different types of motifs, finding that single motifs can explain up to 60% of the variation of motif profiles.
Eigenstate Gibbs Ensemble in Integrable Quantum Systems
Nandy, Sourav; Das, Arnab; Dhar, Abhishek
2016-01-01
The Eigenstate Thermalization Hypothesis implies that for a thermodynamically large system in one of its eigenstates, the reduced density matrix describing any finite subsystem is determined solely by a set of {\\it relevant} conserved quantities. In a generic system, only the energy plays that role and hence eigenstates appear locally thermal. Integrable systems, on the other hand, possess an extensive number of such conserved quantities and hence the reduced density matrix requires specification of an infinite number of parameters (Generalized Gibbs Ensemble). However, here we show by unbiased statistical sampling of the individual eigenstates with a given finite energy density, that the local description of an overwhelming majority of these states of even such an integrable system is actually Gibbs-like, i.e. requires only the energy density of the eigenstate. Rare eigenstates that cannot be represented by the Gibbs ensemble can also be sampled efficiently by our method and their local properties are then s...
Ensemble annealing of complex physical systems
Habeck, Michael
2015-01-01
Algorithms for simulating complex physical systems or solving difficult optimization problems often resort to an annealing process. Rather than simulating the system at the temperature of interest, an annealing algorithm starts at a temperature that is high enough to ensure ergodicity and gradually decreases it until the destination temperature is reached. This idea is used in popular algorithms such as parallel tempering and simulated annealing. A general problem with annealing methods is that they require a temperature schedule. Choosing well-balanced temperature schedules can be tedious and time-consuming. Imbalanced schedules can have a negative impact on the convergence, runtime and success of annealing algorithms. This article outlines a unifying framework, ensemble annealing, that combines ideas from simulated annealing, histogram reweighting and nested sampling with concepts in thermodynamic control. Ensemble annealing simultaneously simulates a physical system and estimates its density of states. The...
Ensemble Forecasting of Major Solar Flares
Guerra, J A; Uritsky, V M
2015-01-01
We present the results from the first ensemble prediction model for major solar flares (M and X classes). Using the probabilistic forecasts from three models hosted at the Community Coordinated Modeling Center (NASA-GSFC) and the NOAA forecasts, we developed an ensemble forecast by linearly combining the flaring probabilities from all four methods. Performance-based combination weights were calculated using a Monte Carlo-type algorithm by applying a decision threshold $P_{th}$ to the combined probabilities and maximizing the Heidke Skill Score (HSS). Using the probabilities and events time series from 13 recent solar active regions (2012 - 2014), we found that a linear combination of probabilities can improve both probabilistic and categorical forecasts. Combination weights vary with the applied threshold and none of the tested individual forecasting models seem to provide more accurate predictions than the others for all values of $P_{th}$. According to the maximum values of HSS, a performance-based weights ...
Quark ensembles with the infinite correlation length
A number of exactly integrable (quark) models of quantum field theory with the infinite correlation length have been considered. It has been shown that the standard vacuum quark ensemble—Dirac sea (in the case of the space-time dimension higher than three)—is unstable because of the strong degeneracy of a state, which is due to the character of the energy distribution. When the momentum cutoff parameter tends to infinity, the distribution becomes infinitely narrow, leading to large (unlimited) fluctuations. Various vacuum ensembles—Dirac sea, neutral ensemble, color superconductor, and BCS state—have been compared. In the case of the color interaction between quarks, the BCS state has been certainly chosen as the ground state of the quark ensemble
Face Recognition using Optimal Representation Ensemble
Li, Hanxi; Gao, Yongsheng
2011-01-01
Recently, the face recognizers based on linear representations have been shown to deliver state-of-the-art performance. In real-world applications, however, face images usually suffer from expressions, disguises and random occlusions. The problematic facial parts undermine the validity of the linear-subspace assumption and thus the recognition performance deteriorates significantly. In this work, we address the problem in a learning-inference-mixed fashion. By observing that the linear-subspace assumption is more reliable on certain face patches rather than on the holistic face, some Bayesian Patch Representations (BPRs) are randomly generated and interpreted according to the Bayes' theory. We then train an ensemble model over the patch-representations by minimizing the empirical risk w.r.t the "leave-one-out margins". The obtained model is termed Optimal Representation Ensemble (ORE), since it guarantees the optimality from the perspective of Empirical Risk Minimization. To handle the unknown patterns in tes...
The ensemble of random Markov matrices
The ensemble of random Markov matrices is introduced as a set of Markov or stochastic matrices with the maximal Shannon entropy. The statistical properties of the stationary distribution π, the average entropy growth rate h and the second-largest eigenvalue ν across the ensemble are studied. It is shown and heuristically proven that the entropy growth rate and second-largest eigenvalue of Markov matrices scale on average with the dimension of the matrices d as h∼log(O(d)) and |ν|∼d−1/2, respectively, yielding the asymptotic relation hτc∼1/2 between the entropy h and the correlation decay time τ = −1/log|ν|. Additionally, the correlation between h and τc is analysed; it decreases with increasing dimension d
DEECO: an ensemble-based component system
Bureš, Tomáš; Gerostathopoulos, I.; Hnětynka, P.; Keznikl, Jaroslav; Kit, M.; Plášil, F.
New York: ACM, 2013, s. 81-90. ISBN 978-1-4503-2122-8. [CBSE 2013. International ACM SIGSOFT Symposium on Component-Based Software Engineering /16./. Vancouver (CA), 17.06.2013-21.06.2013] Grant ostatní: GA AV ČR(CZ) GAP202/11/0312; UK(CZ) SVV-2013-267312 Institutional support: RVO:67985807 Keywords : component model * emergent architecture * component ensembles * autonomic systems * development process * runtime framework Subject RIV: IN - Informatics, Computer Science
Spectral Diagonal Covariance in Ensemble Kalman Filter
Kasanický, Ivan; Eben, Kryštof; Mandel, Jan; Vejmelka, Martin
Munich: Ludwig Maximilians University, 2014. s. 10-10. [ISDA 2014. International Conference on Intelligent Systems Design and Applications. 24.02.2014-28.02.2014, Munich] R&D Projects: GA ČR GA13-34856S Grant ostatní: NSF DMS -1216481 Institutional support: RVO:67985807 Keywords : data assimilation * ensemble Kalman filter * diagonal covariance Subject RIV: DG - Athmosphere Sciences, Meteorology http://www.isda2014.physik.uni-muenchen.de/index.html
Ensemble Data Assimilation: Algorithms and Software
Nerger, Lars
2014-01-01
Ensemble data assimilation is nowadays applied to various problems to estimate a model state and model parameters by combining the model predictions with observational data. At the Alfred Wegener Institute, the assimilation focuses on ocean-sea ice models and coupled ocean-biogeochemical models. The high dimension of realistic models requires particularly efficient algorithms that are also usable on supercomputers. For the application of such filters, the Parallel Data Assimilation Framework ...
Statistical Ensemble Theory of Gompertz Growth Model
Takuya Yamano
2009-01-01
An ensemble formulation for the Gompertz growth function within the framework of statistical mechanics is presented, where the two growth parameters are assumed to be statistically distributed. The growth can be viewed as a self-referential process, which enables us to use the Bose-Einstein statistics picture. The analytical entropy expression pertain to the law can be obtained in terms of the growth velocity distribution as well as the Gompertz function itself for the whole process.
Statistical Ensemble Theory of Gompertz Growth Model
Takuya Yamano
2009-11-01
Full Text Available An ensemble formulation for the Gompertz growth function within the framework of statistical mechanics is presented, where the two growth parameters are assumed to be statistically distributed. The growth can be viewed as a self-referential process, which enables us to use the Bose-Einstein statistics picture. The analytical entropy expression pertain to the law can be obtained in terms of the growth velocity distribution as well as the Gompertz function itself for the whole process.
Ensemble Robustness of Deep Learning Algorithms
Feng, Jiashi; Zahavy, Tom; Kang, Bingyi; Xu, Huan; Mannor, Shie
2016-01-01
The question why deep learning algorithms perform so well in practice has attracted increasing research interest. However, most of well-established approaches, such as hypothesis capacity, robustness or sparseness, have not provided complete explanations, due to the high complexity of the deep learning algorithms and their inherent randomness. In this work, we introduce a new approach~\\textendash~ensemble robustness~\\textendash~towards characterizing the generalization performance of generic ...
Spectral Diagonal Covariance in Ensemble Kalman Filter
Kasanický, Ivan; Eben, Kryštof; Mandel, Jan; Vejmelka, Martin
Munich : Ludwig Maximilians University, 2014. s. 10-10. [ISDA 2014. International Conference on Intelligent Systems Design and Applications. 24.02.2014-28.02.2014, Munich] R&D Projects: GA ČR GA13-34856S Grant ostatní: NSF DMS-1216481 Institutional support: RVO:67985807 Keywords : data assimilation * ensemble Kalman filter * diagonal covariance Subject RIV: DG - Athmosphere Sciences, Meteorology http://www.isda2014.physik.uni-muenchen.de/index.html
Ensemble Models with Trees and Rules
Akdemir, Deniz
2011-01-01
In this article, we have proposed several approaches for post processing a large ensemble of prediction models or rules. The results from our simulations show that the post processing methods we have considered here are promising. We have used the techniques developed here for estimation of quantitative traits from markers, on the benchmark "Bostob Housing"data set and in some simulations. In most cases, the produced models had better prediction performance than, for example, the ones produce...
Analyse expérimentale du comportement biomécanique de deux types d'implants d'ostéosynthèse
Gómez Clemente, Raquel
2010-01-01
Ce projet s´inscrit dans une étude sur l´analyse du comportement biomécanique de deux types d´implants d´ostéosynthèse des fractures condyliennes latérales du coude chez le chien. Il est en relation avec l´entreprise SYNTHES qui fabrique les vis qui vont être utilisées dans l´étude, et des vétérinaires. Ces deux types d´implants sont deux vis différentes, une pleine et une cannulée. Dans ce projet la problématique de l´étude, et la recherche bibliographique faite pour étudier des angles, posi...
Mlih, Mohamed
2012-01-01
Les maladies cardiovasculaires sont la première cause de mortalité dans le monde. Une meilleure compréhension des mécanismes physiopathologiques est nécessaire. Dans ce travail de thèse nous nous sommes intéressés à deux pathologies cardiovasculaires : l’athérosclérose et l’insuffisance cardiaque. Récemment, nous avons identifié le récepteur LRP1 et la protéine adaptatrice ShcA comme étant deux protéines impliquées dans deux de ces pathologies cardiovasculaires. Nousavons montré que ShcA joue...
Multivariate localization methods for ensemble Kalman filtering
Roh, S.
2015-05-08
In ensemble Kalman filtering (EnKF), the small number of ensemble members that is feasible to use in a practical data assimilation application leads to sampling variability of the estimates of the background error covariances. The standard approach to reducing the effects of this sampling variability, which has also been found to be highly efficient in improving the performance of EnKF, is the localization of the estimates of the covariances. One family of localization techniques is based on taking the Schur (entry-wise) product of the ensemble-based sample covariance matrix and a correlation matrix whose entries are obtained by the discretization of a distance-dependent correlation function. While the proper definition of the localization function for a single state variable has been extensively investigated, a rigorous definition of the localization function for multiple state variables has been seldom considered. This paper introduces two strategies for the construction of localization functions for multiple state variables. The proposed localization functions are tested by assimilating simulated observations experiments into the bivariate Lorenz 95 model with their help.
Multivariate localization methods for ensemble Kalman filtering
S. Roh
2015-05-01
Full Text Available In ensemble Kalman filtering (EnKF, the small number of ensemble members that is feasible to use in a practical data assimilation application leads to sampling variability of the estimates of the background error covariances. The standard approach to reducing the effects of this sampling variability, which has also been found to be highly efficient in improving the performance of EnKF, is the localization of the estimates of the covariances. One family of localization techniques is based on taking the Schur (entry-wise product of the ensemble-based sample covariance matrix and a correlation matrix whose entries are obtained by the discretization of a distance-dependent correlation function. While the proper definition of the localization function for a single state variable has been extensively investigated, a rigorous definition of the localization function for multiple state variables has been seldom considered. This paper introduces two strategies for the construction of localization functions for multiple state variables. The proposed localization functions are tested by assimilating simulated observations experiments into the bivariate Lorenz 95 model with their help.
Developments of a Targeted Ensemble Prediction System
Hersbach, H.; Mureau, R.; Opsteegh, J. D.; Barkmeijer, J.
2003-04-01
Based on results presented in a previous paper, an Ensemble Prediction System, especially designed for the short-range to early-medium range for the European domain (TEPS), was further developed. Between 1 January 1999 and 27 February 2000 this system was run for two cases per week. Results were compared to the ensemble prediction system (EPS) that was operational at the European Centre for Medium-Range Weather Forecasts at the time. The focus was on weather parameters. Several configurations were tested. Besides perturbations that optimize total error growth for the European domain at 48 h, perturbations relevant for shorter forecast times were included as well. Firstly, in accordance with EPS, evolved northern hemispheric singular vectors (ETEPS) and secondly, targeted singular vectors with an optimization time of 12 h (STEPS) were added. Compared to EPS, ensemble spread was increased in the short range, having a beneficial effect on statistical properties such as reliability and the frequency of outliers. Spread-skill correlations improved as well. Best performance was found for the STEPS configuration. The impact on Brier scores, relative operating characteristic curves and cost-loss analyses was less clear. From the singular vector point of view, the positive impact of using targeted perturbations is evident. However, after integration (STEPS or ETEPS), it was difficult to find synoptic cases in which this clear impact is still present.
Microcanonical ensemble extensive thermodynamics of Tsallis statistics
The microscopic foundation of the generalized equilibrium statistical mechanics based on the Tsallis entropy is given by using the Gibbs idea of statistical ensembles of the classical and quantum mechanics.The equilibrium distribution functions are derived by the thermodynamic method based upon the use of the fundamental equation of thermodynamics and the statistical definition of the functions of the state of the system. It is shown that if the entropic index ξ = 1/q - 1 in the microcanonical ensemble is an extensive variable of the state of the system, then in the thermodynamic limit z bar = 1/(q - 1)N = const the principle of additivity and the zero law of thermodynamics are satisfied. In particular, the Tsallis entropy of the system is extensive and the temperature is intensive. Thus, the Tsallis statistics completely satisfies all the postulates of the equilibrium thermodynamics. Moreover, evaluation of the thermodynamic identities in the microcanonical ensemble is provided by the Euler theorem. The principle of additivity and the Euler theorem are explicitly proved by using the illustration of the classical microcanonical ideal gas in the thermodynamic limit
Gradient Flow Analysis on MILC HISQ Ensembles
Bazavov, A; Brown, N; DeTar, C; Foley, J; Gottlieb, Steven; Heller, U M; Hetrick, J E; Komijani, J; Laiho, J; Levkova, L; Oktay, M; Sugar, R L; Toussaint, D; Van de Water, R S; Zhou, R
2014-01-01
We report on a preliminary scale determination with gradient-flow techniques on the $N_f = 2 + 1 + 1$ HISQ ensembles generated by the MILC collaboration. The ensembles include four lattice spacings, ranging from 0.15 to 0.06 fm, and both physical and unphysical values of the quark masses. The scales $\\sqrt{t_0}/a$ and $w_0/a$ are computed using Symanzik flow and the cloverleaf definition of $\\langle E \\rangle$ on each ensemble. Then both scales and the meson masses $aM_\\pi$ and $aM_K$ are adjusted for mistunings in the charm mass. Using a combination of continuum chiral perturbation theory and a Taylor series ansatz in the lattice spacing, the results are simultaneously extrapolated to the continuum and interpolated to physical quark masses. Our preliminary results are $\\sqrt{t_0} = 0.1422(7)$fm and $w_0 = 0.1732(10)$fm. We also find the continuum mass-dependence of $w_0$.
Multivariate localization methods for ensemble Kalman filtering
Roh, S.; Jun, M.; Szunyogh, I.; Genton, M. G.
2015-12-01
In ensemble Kalman filtering (EnKF), the small number of ensemble members that is feasible to use in a practical data assimilation application leads to sampling variability of the estimates of the background error covariances. The standard approach to reducing the effects of this sampling variability, which has also been found to be highly efficient in improving the performance of EnKF, is the localization of the estimates of the covariances. One family of localization techniques is based on taking the Schur (element-wise) product of the ensemble-based sample covariance matrix and a correlation matrix whose entries are obtained by the discretization of a distance-dependent correlation function. While the proper definition of the localization function for a single state variable has been extensively investigated, a rigorous definition of the localization function for multiple state variables that exist at the same locations has been seldom considered. This paper introduces two strategies for the construction of localization functions for multiple state variables. The proposed localization functions are tested by assimilating simulated observations experiments into the bivariate Lorenz 95 model with their help.
Ras Conformational Ensembles, Allostery, and Signaling.
Lu, Shaoyong; Jang, Hyunbum; Muratcioglu, Serena; Gursoy, Attila; Keskin, Ozlem; Nussinov, Ruth; Zhang, Jian
2016-06-01
Ras proteins are classical members of small GTPases that function as molecular switches by alternating between inactive GDP-bound and active GTP-bound states. Ras activation is regulated by guanine nucleotide exchange factors that catalyze the exchange of GDP by GTP, and inactivation is terminated by GTPase-activating proteins that accelerate the intrinsic GTP hydrolysis rate by orders of magnitude. In this review, we focus on data that have accumulated over the past few years pertaining to the conformational ensembles and the allosteric regulation of Ras proteins and their interpretation from our conformational landscape standpoint. The Ras ensemble embodies all states, including the ligand-bound conformations, the activated (or inactivated) allosteric modulated states, post-translationally modified states, mutational states, transition states, and nonfunctional states serving as a reservoir for emerging functions. The ensemble is shifted by distinct mutational events, cofactors, post-translational modifications, and different membrane compositions. A better understanding of Ras biology can contribute to therapeutic strategies. PMID:26815308
Ensemble Clustering using Semidefinite Programming with Applications.
Singh, Vikas; Mukherjee, Lopamudra; Peng, Jiming; Xu, Jinhui
2010-05-01
In this paper, we study the ensemble clustering problem, where the input is in the form of multiple clustering solutions. The goal of ensemble clustering algorithms is to aggregate the solutions into one solution that maximizes the agreement in the input ensemble. We obtain several new results for this problem. Specifically, we show that the notion of agreement under such circumstances can be better captured using a 2D string encoding rather than a voting strategy, which is common among existing approaches. Our optimization proceeds by first constructing a non-linear objective function which is then transformed into a 0-1 Semidefinite program (SDP) using novel convexification techniques. This model can be subsequently relaxed to a polynomial time solvable SDP. In addition to the theoretical contributions, our experimental results on standard machine learning and synthetic datasets show that this approach leads to improvements not only in terms of the proposed agreement measure but also the existing agreement measures based on voting strategies. In addition, we identify several new application scenarios for this problem. These include combining multiple image segmentations and generating tissue maps from multiple-channel Diffusion Tensor brain images to identify the underlying structure of the brain. PMID:21927539
Quantum statistical ensemble for emissive correlated systems
Shakirov, Alexey M.; Shchadilova, Yulia E.; Rubtsov, Alexey N.
2016-06-01
Relaxation dynamics of complex quantum systems with strong interactions towards the steady state is a fundamental problem in statistical mechanics. The steady state of subsystems weakly interacting with their environment is described by the canonical ensemble which assumes the probability distribution for energy to be of the Boltzmann form. The emergence of this probability distribution is ensured by the detailed balance of the transitions induced by the interaction with the environment. Here we consider relaxation of an open correlated quantum system brought into contact with a reservoir in the vacuum state. We refer to such a system as emissive since particles irreversibly evaporate into the vacuum. The steady state of the system is a statistical mixture of the stable eigenstates. We found that, despite the absence of the detailed balance, the stationary probability distribution over these eigenstates is of the Boltzmann form in each N -particle sector. A quantum statistical ensemble corresponding to the steady state is characterized by different temperatures in the different sectors, in contrast to the Gibbs ensemble. We investigate the transition rates between the eigenstates to understand the emergence of the Boltzmann distribution and find their exponential dependence on the transition energy. We argue that this property of transition rates is generic for a wide class of emissive quantum many-body systems.
Multivariate localization methods for ensemble Kalman filtering
Roh, S.
2015-12-03
In ensemble Kalman filtering (EnKF), the small number of ensemble members that is feasible to use in a practical data assimilation application leads to sampling variability of the estimates of the background error covariances. The standard approach to reducing the effects of this sampling variability, which has also been found to be highly efficient in improving the performance of EnKF, is the localization of the estimates of the covariances. One family of localization techniques is based on taking the Schur (element-wise) product of the ensemble-based sample covariance matrix and a correlation matrix whose entries are obtained by the discretization of a distance-dependent correlation function. While the proper definition of the localization function for a single state variable has been extensively investigated, a rigorous definition of the localization function for multiple state variables that exist at the same locations has been seldom considered. This paper introduces two strategies for the construction of localization functions for multiple state variables. The proposed localization functions are tested by assimilating simulated observations experiments into the bivariate Lorenz 95 model with their help.
Hermon, Ella
2015-01-01
La gestion de l’eau, conçue comme un patrimoine culturel par le filtre de son histoire, est indissociable des écosystèmes des bords de l’eau que nous avons identifiés avec le concept de RIPARIA. Sa définition comme concept environnemental à la recherche d’une méthode d’analyse systémique puise ses racines dans l’évolution diachronique des concepts environnementaux des deux rives de l’Atlantique. Deux approches parallèles de la définition de concepts environnementaux, ont ...
A.H. CHAPMAN
1998-09-01
Full Text Available A case of folie à deux dissociative (dissociative hysteria disorder in an 8 and 12 year-old sister and brother is presented. Illnesses of this type are very rare and there is little medical literature on this subject. Our patients, almost simultaneously, abruptly had complete loss of memory, disorientation, loss of awareness about who they were, and much anxiety, which lasted about 15 hours. Both patients were physically well and no abnormalities were found on physical examination, routines laboratory tests and EEG studies. Speculations about the emotional and interpersonal causes of this illness in these two patients are given.É apresentado um caso da desordem dissociativa folie à deux (histeria dissociativa em um casal de irmãos, sendo que o menino tem 12 anos e a menina 8. Doenças desse tipo são raras e existem poucas referências sobre o assunto na literatura médica. Os pacientes por nós atendidos, de repente e quase simultaneamente, apresentaram distúrbios acentuados da memória, desorientação, perda de auto-identidade e muita ansiedade; esse estado confusional durou aproximadamente 15 horas. Os dois tinham boa saúde física e não apresentavam anormalidades no exame clínico. Os exames laboratoriais de rotina estavam normais. Foram avaliados por meio de EEGs que estavam dentro dos limites da normalidade. Na discussão, são apresentadas considerações especulativas sobre as causas emocionais e interpessoais que possam ter propiciado o aparecimento dessa desordem nos dois pacientes.
Ensemble Data Assimilation Without Ensembles: Methodology and Application to Ocean Data Assimilation
Keppenne, Christian L.; Rienecker, Michele M.; Kovach, Robin M.; Vernieres, Guillaume
2013-01-01
Two methods to estimate background error covariances for data assimilation are introduced. While both share properties with the ensemble Kalman filter (EnKF), they differ from it in that they do not require the integration of multiple model trajectories. Instead, all the necessary covariance information is obtained from a single model integration. The first method is referred-to as SAFE (Space Adaptive Forecast error Estimation) because it estimates error covariances from the spatial distribution of model variables within a single state vector. It can thus be thought of as sampling an ensemble in space. The second method, named FAST (Flow Adaptive error Statistics from a Time series), constructs an ensemble sampled from a moving window along a model trajectory. The underlying assumption in these methods is that forecast errors in data assimilation are primarily phase errors in space and/or time.
The MIP ensemble simulation: local ensemble statistics in the Cosmic Web
Aragon-Calvo, M. A.
2016-01-01
We present a new technique that allows us to compute ensemble statistics on a local basis, directly relating halo properties to their local environment. This is achieved by the use of a correlated ensemble in which the large-scale structure (LSS) is common to all realizations while having each an independent halo population. The correlated ensemble can be stacked, effectively increasing the halo number density by an arbitrary factor, thus breaking the fundamental limit in the halo number density given by the halo mass function. This technique allows us to compute local ensemble statistics of the matter/halo distribution at any position in the simulation box, while removing the intrinsic stochasticity in the halo formation process and directly relating halo properties to their environment. We introduce the Multum In Parvo correlated ensemble simulation consisting of 220 realizations on a 32 h-1 Mpc box with 2563 particles each. This is equivalent in terms of effective volume and number of particles to a box of ˜193 h-1 Mpc of side with ˜15403 particles containing ˜5 × 106 haloes with a minimum mass of 3.25 × 109 h-1 M⊙. The potential of the technique presented here is illustrated by computing the local ensemble statistics of the halo ellipticity and halo shape-LSS alignment. We show that, while there are general trends in the ellipticity and alignment of haloes with their LSS, there are also significant spatial variations which has important implications for observational studies of galaxy shape and alignment.
De praeceptis ferendis: good practice in multi-model ensembles
I. Kioutsioukis
2014-06-01
Full Text Available Ensembles of air quality models have been formally and empirically shown to outperform single models in many cases. Evidence suggests that ensemble error is reduced when the members form a diverse and accurate ensemble. Diversity and accuracy are hence two factors that should be taken care of while designing ensembles in order for them to provide better predictions. There exists a trade-off between diversity and accuracy for which one cannot be gained without expenses of the other. Theoretical aspects like the bias-variance-covariance decomposition and the accuracy-diversity decomposition are linked together and support the importance of creating ensemble that incorporates both the elements. Hence, the common practice of unconditional averaging of models without prior manipulation limits the advantages of ensemble averaging. We demonstrate the importance of ensemble accuracy and diversity through an inter-comparison of ensemble products for which a sound mathematical framework exists, and provide specific recommendations for model selection and weighting for multi model ensembles. To this end we have devised statistical tools that can be used for diagnostic evaluation of ensemble modelling products, complementing existing operational methods.
Deux extraits commentés des Basses Œuvres1 de ‘Abduh Khāl
Lagrange, Frédéric
2014-01-01
Le romancier saoudien ‘Abduh Khāl, dans son roman Tarmī bi‑sharar (Les Basses Œuvres) paru en 2009 et couronné par l’International Prize for Arab Fiction en 2010, tend un miroir peu flatteur au Royaume wahhabite : ce monologue d’un tortionnaire violeur au service d’un mystérieux Maître du Palais dans une Djedda déformée par l’affairisme figurant allégoriquement le régime présente un pays corrompu par sa soumission à l’absolutisme. Deux extraits sont ici commentés, en soulignant les rapports i...
Mamoudou, Savadogo; Lassina, Dao; Fla, Koueta
2015-01-01
Nous rapportons deux cas d'infection à Pseudomonas aeruginosa: un cas de méningite et un cas d'infection urinaire. Les auteurs rappellent qu’à côté des étiologies classiques des méningites et des infections urinaires, des germes résistants comme Pseudomonas aeruginosa peuvent être responsables d'infections à localisation méningées et urinaires et dont il faut connaître pour une bonne prise en charge. Le traitement de ces infections requiert un antibiogramme au regard de la grande capacité de résistance de Pseudomonas aeruginosa en milieu hospitalier. La limitation des gestes invasifs et l'application rigoureuse des mesures de prévention des infections en milieu hospitalier contribueront à lutter efficacement contre ces infections en milieu de soins. PMID:26491521
À propos du compte rendu des deux volumes de Chants populaires de la Grande Lande, de Félix Arnaudin
Mabru, Lothaire
2010-01-01
Dans le précédent volume des Cahiers de musiques traditionnelles, Eliane Gauzit et Pierre Bec ont produit un compte rendu concernant les deux tomes des Chants populaires de la Grande Lande de Félix Arnaudin, auxquels j’avais participé. Dans ce texte ils m’accusent de manque de rigueur scientifique et de négligence dans mon travail d’édition des chants collectés par Arnaudin. Ce n’est pas la première fois qu’ils s’en prennent à moi à ce sujet, puisqu’ils ont publiquement émis leurs critiques à...
Lehner, T.
1988-01-01
Le battement de deux ondes électromagnétiques dans un plasma pour produire une onde longitudinale (plasmon ou phonon) est réalisé expérimentalement à l'aide d'un double banc micro-onde en bande centimétrique. La détection du couplage se fait : (a) soit par une méthode d'absorption directe sur l'une des pompes ; (b) soit par diffusion hétérodyne d'une troisième onde dans des conditions de quasi-absorption. Ces méthodes de détection sont optimales : la première satisfait la relation de Manley-R...
Le modèle probabiliste de l'alignement local de deux séquences
Nicodème, Pierre
1997-01-01
Nous décrivons le modèle probabiliste utilisé pour calibrer l'alignement local de deux séquences, quand un schéma de score additif est utilisé. Ce modèle est utilisé en particulier par le logiciel BLAST (Basic Local Alignment Search Tool), qui est employé fréquemment par les biologistes. Asymptotiquement, la probabilité associée au score d'un alignement optimal vérifie une loi des valeurs extrêmes. Nous analysons différents aspects des outils mathématiques (modèles de marche aléatoire, décomp...
Écritures hypermédiatiques: remarques sur deux cédéroms d'auteur
Clément, Jean
2000-01-01
L'avènement du livre numérique fait apparaître de nouvelles formes d'écriture. Dans le domaine de la fiction, en particulier, on assiste à la naissance d'un nouveau genre à la croisée des jeux vidéos, de l'hypertexte et de la littérature expérimentale. À travers deux exemples, ce sont quelques-unes des caractéristiques du genre qui sont étudiées ici : refondation du pacte de lecture, dissémination des énoncés, nouvelles modalités narratives, déconstruction du récit, interactivité....
Seasonal hydrological ensemble forecasts over Europe
Arnal, Louise; Wetterhall, Fredrik; Stephens, Elisabeth; Cloke, Hannah; Pappenberger, Florian
2016-04-01
This study investigates the limits of predictability in dynamical seasonal discharge forecasting, in both space and time, over Europe. Seasonal forecasts have an important socioeconomic value. Applications are numerous and cover hydropower management, spring flood prediction, low flow prediction for navigation and agricultural water demands. Additionally, the constant increase in NWP skill for longer lead times and the predicted increase in the intensity and frequency of hydro-meteorological extremes, have amplified the incentive to promote and further improve hydrological forecasts on sub-seasonal to seasonal timescales. In this study, seasonal hydrological forecasts (SEA), driven by the ECMWF's System 4 in hindcast mode, were analysed against an Ensemble Streamflow Prediction (ESP) benchmark. The ESP was forced with an ensemble of resampled historical meteorological observations and started with perfect initial conditions. Both forecasts were produced by the LISFLOOD model, run on the pan-European scale with a spatial resolution of 5 by 5 km. The forecasts were issued monthly on a daily time step, from 1990 until the current time, up to a lead time of 7 months. The seasonal discharge forecasts were analysed against the ESP on a catchment scale in terms of their accuracy, skill and sharpness, using a diverse set of verification metrics (e.g. KGE, CRPSS and ROC). Additionally, a reverse-ESP was constructed by forcing the LISFLOOD model with a single perfect meteorological set of observations and initiated from an ensemble of resampled historical initial conditions. The comparison of the ESP with the reverse-ESP approach enabled the identification of the respective contribution of meteorological forcings and hydrologic initial conditions errors to seasonal discharge forecasting uncertainties in Europe. These results could help pinpoint target elements of the forecasting chain which, after being improved, could lead to substantial increase in discharge predictability
Bayesian ensemble refinement by replica simulations and reweighting
Hummer, Gerhard
2015-01-01
We describe different Bayesian ensemble refinement methods, examine their interrelation, and discuss their practical application. With ensemble refinement, the properties of dynamic and partially disordered (bio)molecular structures can be characterized by integrating a wide range of experimental data, including measurements of ensemble-averaged observables. We start from a Bayesian formulation in which the posterior is a functional that ranks different configuration space distributions. By maximizing this posterior, we derive an optimal Bayesian ensemble distribution. For discrete configurations, this optimal distribution is identical to that obtained by the maximum entropy "ensemble refinement of SAXS" (EROS) formulation. Bayesian replica ensemble refinement enhances the sampling of relevant configurations by imposing restraints on averages of observables in coupled replica molecular dynamics simulations. We find that the strength of the restraint scales with the number of replicas and we show that this sca...
Skill forecasting from ensemble predictions of wind power
Pinson, Pierre; Nielsen, Henrik Aalborg; Madsen, Henrik;
2009-01-01
risk indices aiming to give a comprehensive signal on the expected level of forecast uncertainty. Ensemble predictions of wind generation are used as input. A proposal for the definition of prediction risk indices is given. Such skill forecasts are based on the spread of ensemble forecasts (i.e. a set......Optimal management and trading of wind generation calls for the providing of uncertainty estimates along with the commonly provided short-term wind power point predictions. Alternative approaches for the use of probabilistic forecasting are introduced. More precisely, focus is given to prediction...... power ensemble predictions are derived from the conversion of ECMWF and NCEP ensemble forecasts of meteorological variables to wind power ensemble forecasts, as well as by a lagged average approach alternative. The ability of prediction risk indices calculated from the various types of ensembles...
The role of Gibbs ensembles in statistical thermodynamics
The motives are elucidated that force Gibbs to introduce the notion of ensemble when formulating the statistical thermodynamics. The term 'Gibbs ensemble' is analyzed in detail and its relation to the notion of probability is revealed. The examination of contemporary literature in pertaining field shows clearly that the term 'Gibbs ensemble' is used now only as a synonym of the statistical distribution function and nothing else. This implies, in particular, that the initial notion of the Gibbs ensemble, as the set of a large (more precisely, infinite) number of copies of the thermodynamical system under consideration, becomes now unnecessary in the mathematical tools of the statistical thermodynamics and when presenting its essentials, too. Furthermore, in its original meaning the term 'Gibbs ensemble' served in the last century only for definition of probability. Now a proper place of this term is presumably in interpretation of the statistical thermodynamics in a complete analogy as the quantum ensembles have been proposed for interpretation of quantum mechanics
A Framework for Non-Equilibrium Statistical Ensemble Theory
BI Qiao; HE Zu-Tan; LIU Jie
2011-01-01
Since Gibbs synthesized a general equilibrium statistical ensemble theory, many theorists have attempted to generalized the Gibbsian theory to non-equilibrium phenomena domain, however the status of the theory of nonequilibrium phenomena can not be said as firm as well established as the Gibbsian ensemble theory. In this work, we present a framework for the non-equilibrium statistical ensemble formalism based on a subdynamic kinetic equation (SKE) rooted from the Brussels-Austin school and followed by some up-to-date works. The constructed key is to use a similarity transformation between Gibbsian ensembles formalism based on Liouville equation and the subdynamic ensemble formalism based on the SKE. Using this formalism, we study the spin-Boson system, as cases of weak coupling or strongly coupling, and obtain the reduced density operators for the Canonical ensembles easily.
Cavity-Controlled Chemistry in Molecular Ensembles
Herrera, Felipe; Spano, Frank C.
2016-06-01
The demonstration of strong and ultrastrong coupling regimes of cavity QED with polyatomic molecules has opened new routes to control chemical dynamics at the nanoscale. We show that strong resonant coupling of a cavity field with an electronic transition can effectively decouple collective electronic and nuclear degrees of freedom in a disordered molecular ensemble, even for molecules with high-frequency quantum vibrational modes having strong electron-vibration interactions. This type of polaron decoupling can be used to control chemical reactions. We show that the rate of electron transfer reactions in a cavity can be orders of magnitude larger than in free space for a wide class of organic molecular species.
Supervised Ensemble Classification of Kepler Variable Stars
Bass, Gideon
2016-01-01
Variable star analysis and classification is an important task in the understanding of stellar features and processes. While historically classifications have been done manually by highly skilled experts, the recent and rapid expansion in the quantity and quality of data has demanded new techniques, most notably automatic classification through supervised machine learning. We present an expansion of existing work on the field by analyzing variable stars in the {\\em Kepler} field using an ensemble approach, combining multiple characterization and classification techniques to produce improved classification rates. Classifications for each of the roughly 150,000 stars observed by {\\em Kepler} are produced separating the stars into one of 14 variable star classes.
Modeling Coordination Problems in a Music Ensemble
Frimodt-Møller, Søren R.
2008-01-01
This paper considers in general terms, how musicians are able to coordinate through rational choices in a situation of (temporary) doubt in an ensemble performance. A fictitious example involving a 5-bar development in an unknown piece of music is analyzed in terms of epistemic logic, more...... specifically a multi-agent system, where it is shown that perfect coordination can only be certain to take place if the musicians have common knowledge of certain rules of the composition. We subsequently argue, however, that the musicians need not agree on the central features of the piece of music in order...
Cavity-controlled chemistry in molecular ensembles
Herrera, Felipe
2015-01-01
The demonstration of strong and ultrastrong coupling regimes of cavity QED with polyatomic molecules has opened new routes to control chemical dynamics at the nanoscale. We show that strong resonant coupling of a cavity field with an electronic transition can effectively decouple collective electronic and nuclear degrees of freedom in a disordered molecular ensemble, even for molecules with high-frequency quantum vibrational modes having strong electron-vibration interactions. This type of polaron decoupling can be used to control chemical reactions. We show that the rate of electron transfer reactions in a cavity can be orders of magnitude larger than in free space, for a wide class of organic molecular species.
Probabilistic Flash Flood Forecasting using Stormscale Ensembles
Hardy, J.; Gourley, J. J.; Kain, J. S.; Clark, A.; Novak, D.; Hong, Y.
2013-12-01
Flash flooding is one of the most costly and deadly natural hazards in the US and across the globe. The loss of life and property from flash floods could be mitigated with better guidance from hydrological models, but these models have limitations. For example, they are commonly initialized using rainfall estimates derived from weather radars, but the time interval between observations of heavy rainfall and a flash flood can be on the order of minutes, particularly for small basins in urban settings. Increasing the lead time for these events is critical for protecting life and property. Therefore, this study advances the use of quantitative precipitation forecasts (QPFs) from a stormscale NWP ensemble system into a distributed hydrological model setting to yield basin-specific, probabilistic flash flood forecasts (PFFFs). Rainfall error characteristics of the individual members are first diagnosed and quantified in terms of structure, amplitude, and location (SAL; Wernli et al., 2008). Amplitude and structure errors are readily correctable due to their diurnal nature, and the fine scales represented by the CAPS QPF members are consistent with radar-observed rainfall, mainly showing larger errors with afternoon convection. To account for the spatial uncertainty of the QPFs, we use an elliptic smoother, as in Marsh et al. (2012), to produce probabilistic QPFs (PQPFs). The elliptic smoother takes into consideration underdispersion, which is notoriously associated with stormscale ensembles, and thus, is good for targeting the approximate regions that may receive heavy rainfall. However, stormscale details contained in individual members are still needed to yield reasonable flash flood simulations. Therefore, on a case study basis, QPFs from individual members are then run through the hydrological model with their predicted structure and corrected amplitudes, but the locations of individual rainfall elements are perturbed within the PQPF elliptical regions using Monte
Black Hole Statistical Mechanics and The Angular Velocity Ensemble
Thomson, Mitchell; Dyer, Charles C.
2012-01-01
An new ensemble - the angular velocity ensemble - is derived using Jaynes' method of maximising entropy subject to prior information constraints. The relevance of the ensemble to black holes is motivated by a discussion of external parameters in statistical mechanics and their absence from the Hamiltonian of general relativity. It is shown how this leads to difficulty in deriving entropy as a function of state and recovering the first law of thermodynamics from the microcanonical and canonica...
Random matrix ensembles with column/row constraints: II
We numerically analyze the random matrix ensembles of real-symmetric matrices with column/row constraints for many system conditions e.g. disorder type, matrix-size and basis-connectivity. The results reveal a rich behavior hidden beneath the spectral statistics and also confirm our analytical predictions, presented in part I of this paper, about the analogy of their spectral fluctuations with those of a critical Brownian ensemble which appears between Poisson and Gaussian orthogonal ensemble. (paper)
Enhanced ensemble-based 4DVar scheme for data assimilation
Yang, Yin; Robinson, Cordelia; Heitz, Dominique; Mémin, Etienne
2015-01-01
International audience Ensemble based optimal control schemes combine the components of ensemble Kalman filters and variational data assimilation (4DVar). They are trendy because they are easier to implement than 4DVar. In this paper, we evaluate a modified version of an ensemble based optimal control strategy for image data assimilation. This modified method is assessed with a Shallow Water model combined with synthetic data and original incomplete experimental depth sensor observations. ...
Data assimilation with the weighted ensemble Kalman filter
Papadakis, Nicolas; Mémin, Etienne; Cuzol, Anne; Gengembre, Nicolas
2010-01-01
In this paper, two data assimilation methods based on sequential Monte Carlo sampling are studied and compared: the ensemble Kalman filter and the particle filter. Each of these techniques has its own advantages and drawbacks. In this work, we try to get the best of each method by combining them. The proposed algorithm, called the weighted ensemble Kalman filter, consists to rely on the Ensemble Kalman Filter updates of samples in order to define a proposal distribution for the particle filte...
The dynamics of exploitation in ensembles of source and sink
Friedrich, T.
2012-01-01
The ensemble is a new entity on a higher level of complexity composed of source and sink. When substrate is transferred from source to sink within the transfer space or the ensemble space non-linearity is observed. Saturating production functions of source and sink in combination with linear cost functions generate superadditivity and subadditivity in the productivity of the ensemble. In a reaction chain the source produces a product that will be used by the sink to produce a different pr...
Unconditional two-mode squeezing of separated atomic ensembles
Parkins, A S; Solano, E
2005-01-01
We propose schemes for the unconditional preparation of a two-mode squeezed state of effective bosonic modes realized in a pair of atomic ensembles interacting collectively with optical cavity and laser fields. The scheme uses Raman transitions between stable atomic ground states and under ideal conditions produces pure entangled states in the steady state. The scheme works both for ensembles confined within a single cavity and for ensembles confined in separate, cascaded cavities.
Enhanced Sampling in the Well-Tempered Ensemble
Bonomi, M.; Parrinello, M
2009-01-01
We introduce the well-tempered ensemble (WTE) which is the biased ensemble sampled by well-tempered metadynamics when the energy is used as collective variable. WTE can be designed so as to have approximately the same average energy as the canonical ensemble but much larger fluctuations. These two properties lead to an extremely fast exploration of phase space. An even greater efficiency is obtained when WTE is combined with parallel tempering. Unbiased Boltzmann averages are computed on the ...
Mixture EMOS model for calibrating ensemble forecasts of wind speed
Baran, Sándor; Lerch, Sebastian
2015-01-01
Ensemble model output statistics (EMOS) is a statistical tool for post-processing forecast ensembles of weather variables obtained from multiple runs of numerical weather prediction models in order to produce calibrated predictive probability density functions (PDFs). The EMOS predictive PDF is given by a parametric distribution with parameters depending on the ensemble forecasts. We propose an EMOS model for calibrating wind speed forecasts based on weighted mixtures of truncated normal (TN)...
Triality and the grand canonical ensemble in QCD
QCD in the usual finite temperature formulation is using the grand canonical ensemble with chemical potential zero. We demonstrate that this description may give wrong predictions. QCD in the canonical formulation does not explicitly break Z(3) symmetry. It behaves in this sense like pure gluonic QCD. There are no metastable states in the canonical ensemble description as predicted in the grand canonical ensemble formalism. ((orig.))
Convergence of the Square Root Ensemble Kalman Filter in the Large Ensemble Limit
Kwiatkowski, E.; Mandel, Jan
2015-01-01
Roč. 3, č. 1 (2015), s. 1-17. ISSN 2166-2525 R&D Projects: GA ČR GA13-34856S Institutional support: RVO:67985807 Keywords : data assimilation * Lp laws of large numbers * Hilbert space * ensemble Kalman filter Subject RIV: IN - Informatics, Computer Science
Bayesian ensemble refinement by replica simulations and reweighting
Hummer, Gerhard; Köfinger, Jürgen
2015-12-01
We describe different Bayesian ensemble refinement methods, examine their interrelation, and discuss their practical application. With ensemble refinement, the properties of dynamic and partially disordered (bio)molecular structures can be characterized by integrating a wide range of experimental data, including measurements of ensemble-averaged observables. We start from a Bayesian formulation in which the posterior is a functional that ranks different configuration space distributions. By maximizing this posterior, we derive an optimal Bayesian ensemble distribution. For discrete configurations, this optimal distribution is identical to that obtained by the maximum entropy "ensemble refinement of SAXS" (EROS) formulation. Bayesian replica ensemble refinement enhances the sampling of relevant configurations by imposing restraints on averages of observables in coupled replica molecular dynamics simulations. We show that the strength of the restraints should scale linearly with the number of replicas to ensure convergence to the optimal Bayesian result in the limit of infinitely many replicas. In the "Bayesian inference of ensembles" method, we combine the replica and EROS approaches to accelerate the convergence. An adaptive algorithm can be used to sample directly from the optimal ensemble, without replicas. We discuss the incorporation of single-molecule measurements and dynamic observables such as relaxation parameters. The theoretical analysis of different Bayesian ensemble refinement approaches provides a basis for practical applications and a starting point for further investigations.