722 research outputs found
Regulating the financial analysis industry : Is the European Directive effective ?
In the recent years, the US and the EC have witnessed the adoption of new regulations focused on financial analysts. This study investigates whether the European regulations, known as the Market Abuse Directive (MAD) changed the distribution of recommendations and increased their credibility...financial analysts ; conflicts of interest ; recommendations ; Market Abuse Directive; European Union
Integer and fractional charge Lorentzian voltage pulses analyzed in the frame of Photon-assisted Shot Noise
The periodic injection of electrons in a quantum conductor using periodic
voltage pulses applied on a contact is studied in the energy and time-domain
using shot noise computation in order to make comparison with experiments. We
particularly consider the case of periodic Lorentzian voltage pulses. When
carrying integer charge, they are known to provide electronic states with a
minimal number of excitations, while other type of pulses are all accompanied
by an extra neutral cloud of electron and hole excitations. This paper focuses
on the low frequency shot noise which arises when the pulse excitations are
partitioned by a single scatterer in the framework of the Photo Assisted Shot
Noise (PASN) theory. As a unique tool to count the number of excitations
carried per pulse, shot noise reveals that pulses of arbitrary shape and
arbitrary charge show a marked minimum when the charge is integer. Shot noise
spectroscopy is also considered to perform energy-domain characterization of
the charge pulses. In particular it reveals the striking asymmetrical spectrum
of Lorentzian pulses. Finally, time-domain information is obtained from Hong Ou
Mandel like noise correlations when two trains of pulses generated on opposite
contacts collide on the scatterer. As a function of the time delay between
pulse trains, the noise is shown to measure the electron wavepacket
autocorrelation function for integer Lorentzian thanks to electron
antibunching. In order to make contact with recent experiments all the
calculations are made at zero and finite temperature
Bilan des connaissances de la dynamique de lâĂ©rosion des cĂŽtes du QuĂ©bec maritime laurentien
Un bilan des connaissances de la dynamique de lâĂ©rosion cĂŽtiĂšre dans lâestuaire et le golfe du Saint-Laurent montre que le recul du littoral dans les formations meubles est trĂšs important, variant gĂ©nĂ©ralement entre 0,5 et 2 m/an. Les donnĂ©es indiquent une accĂ©lĂ©ration rĂ©cente du phĂ©nomĂšne, ce qui va dans le sens de la tendance mondiale apprĂ©hendĂ©e dans le contexte des changements climatiques. Il semble que les cĂŽtes Ă marais maritimes soient les plus sensibles, certains schorres supĂ©rieurs ayant dĂ©jĂ disparu au cours de la derniĂšre dĂ©cennie. Cela sâexplique par le fait que, dans les rĂ©gions froides, les marais maritimes sont affectĂ©s par un grand nombre de processus, dont le sapement par les vagues et les courants de marĂ©e, lâaffouillement et lâarrachement par les glaces littorales, les processus cryogĂ©niques, la dessiccation et les activitĂ©s anthropiques et biologiques. Si lâaction des vagues pendant les marĂ©es de vive eau et les tempĂȘtes conditionne, dans une large mesure, le recul des falaises sableuses, les processus cryogĂ©niques et hydrogĂ©ologiques sont les principaux responsables de la rĂ©activation et de lâĂ©rosion des falaises Ă base argileuse et silteuse des complexes deltaĂŻques. Ă lâĂ©chelle du QuĂ©bec maritime, des Ă©tudes quantitatives saisonniĂšres sont nĂ©cessaires pour bien comprendre la rĂ©partition spatio-temporelle des processus et surtout, les facteurs et les causes qui rĂ©gissent lâĂ©rosion cĂŽtiĂšre dans les rĂ©gions tempĂ©rĂ©es froides.A review of coastal erosion dynamics in the St. Lawrence maritime Estuary and Gulf demonstrates that shoreline retreat in unconsolidated formations varies between 0.5 and 2.0 m/yr. The data indicate a recent acceleration of coastal erosion that corresponds with the anticipated global trend resulting from climatic change. Saltmarshes are the most sensitive to coastal erosion, with some upper marshes having already disappeared in the last decade. In cold regions saltmarshes are affected by numerous processes such as undercutting by waves and tidal currents, ice foot scouring, freeze-thaw processes, wetting and drying processes, biologic processes and anthropogenic activities. Wave action during spring tides or storm surges is an important factor causing shoreline retreat in sandy cliffs, whereas cryogenic and hydrogeological processes are mainly responsible for reactivation and erosion of silt and clay-based cliffs in deltaic environments. In maritime QuĂ©bec, quantitative seasonal studies are needed to develop a better understanding of spatio-temporal process distribution and to better assess the causes that regulate coastal erosion in mid-latitude cold regions
La terrasse Mitis Ă la pointe de Mille-Vaches (pĂ©ninsule de Portneuf), rive nord de lâestuaire maritime du Saint-Laurent : nature des dĂ©pĂŽts et Ă©volution du niveau marin relatif Ă lâholocĂšne
La basse terrasse Ă lâextrĂ©mitĂ© sud-ouest de la pĂ©ninsule de Portneuf, sur la Haute CĂŽte-Nord du Saint-Laurent, correspond Ă la terrasse Mitis prĂ©sente dans quelques autres localitĂ©s de la rive nord de lâestuaire. EntiĂšrement composĂ©e de matĂ©riaux meubles dĂ©tritiques, elle comprend plusieurs unitĂ©s, la plupart sableuses, dâune Ă©paisseur supĂ©rieure Ă 3 m. Mises en place en milieu littoral et intertidal, ces unitĂ©s reposent sur un dĂ©pĂŽt de sable fin gris, infratidal, lui-mĂȘme susjacent au substrat limono-argileux dĂ©posĂ© dans la Mer de Goldthwait, il y a >9,5 ka. Un dĂ©pĂŽt de limon sableux, gris, laminĂ©, contenant des dĂ©bris de plantes en place correspondant Ă un faciĂšs de schorre infĂ©rieur, coiffe la sĂ©quence sableuse. Par endroits, ce dĂ©pĂŽt est lui-mĂȘme recouvert dâune couche de tourbe de 25â30 cm dâĂ©paisseur. LâunitĂ© Ă la base de la falaise active a Ă©tĂ© mise en place entre 1990 ± 60 et 2740 ± 70 BP. Les unitĂ©s sableuses au-dessus datent de 1570 ± 60 Ă 1880 ± 90 BP, alors que lâunitĂ© limoneuse Ă faciĂšs de schorre infĂ©rieur a donnĂ© un Ăąge au 14C allant de 1570 ± 50 Ă 1970 ± 70 BP. LâĂąge mĂ©dian de la terrasse Mitis est de 1880 ± 90 BP, alors que si on prend en compte uniquement les dates pour lâunitĂ© limoneuse Ă faciĂšs de schorre infĂ©rieur, il est de 1830 ± 60 BP. LâĂ©dification de la terrasse Mitis Ă la pointe de Mille-Vaches est donc contemporaine de la plupart des sites des deux rives de lâestuaire. Le substrat argileux de la vaste batture en face de la terrasse, qui se prolonge sous celle-ci, a Ă©tĂ© Ă©rodĂ© lors dâun bas niveau marin pendant lâHolocĂšne moyen qui fut suivi dâune remontĂ©e du niveau de quelques mĂštres. Un glissement de terrain historique, survenu vraisemblablement lors du sĂ©isme de 1663, caractĂ©rise la partie supĂ©rieure de lâestran en face de la falaise active.The low terrace at the SW extremity of the Portneuf Peninsula, on the north shore of the Lower St. Lawrence estuary, is an equivalent of the Mitis terrace occurring at a few other localities. The terrace is entirely made of detritic sediments. The various units, mostly fine to coarse sand deposited in the shore zone, are over 3 m in thickness. These sediments appear to unconformably overlie a subtidal dark grey fine sand resting on a surface eroded into a Goldthwait Sea clay deposit older than 9.5 ka. At the surface of the terrace, there is a grey, laminated sandy silt deposit with plant remains in situ (a lower marsh facies), locally covered by a thin (25â30 cm) layer of peat. The sand unit at the base of the studied exposure has been dated 1990 ± 60 to 2740 ± 70 BP. The overlying sandy units are dated 1570 ± 60 to 1880 ± 90 BP, whereas the silt unit at the surface is dated 1570 ± 50 to 1970 ± 70 BP. The median age of the terrace is 1880 ± 90 BP, whereas if we use only the 14C dates for the silt unit, it is 1830 ± 60 BP. At Pointe de Mille-Vaches, the Mitis terrace is thus contemporaneous with most localities on both shores of the estuary. The substrate of the wide tidal flat in front of the Mitis terrace (an erosion surface underlying the terrace) was cut into the marine clay during a mid-Holocene lowstand, which was followed by a rising sea level of a few meters. An historical landslide, which possibly occurred during the 1663 seismic event, characterizes the upper part of the tidal zone in front of the active cliff
The SIMBAD astronomical database
Simbad is the reference database for identification and bibliography of
astronomical objects. It contains identifications, `basic data', bibliography,
and selected observational measurements for several million astronomical
objects. Simbad is developed and maintained by CDS, Strasbourg. Building the
database contents is achieved with the help of several contributing institutes.
Scanning the bibliography is the result of the collaboration of CDS with
bibliographers in Observatoire de Paris (DASGAL), Institut d'Astrophysique de
Paris, and Observatoire de Bordeaux. When selecting catalogues and tables for
inclusion, priority is given to optimal multi-wavelength coverage of the
database, and to support of research developments linked to large projects. In
parallel, the systematic scanning of the bibliography reflects the diversity
and general trends of astronomical research.
A WWW interface to Simbad is available at: http://simbad.u-strasbg.fr/SimbadComment: 14 pages, 5 Postscript figures; to be published in A&A
PAC-Bayesian Learning of Aggregated Binary Activated Neural Networks with Probabilities over Representations
Considering a probability distribution over parameters is known as an
efficient strategy to learn a neural network with non-differentiable activation
functions. We study the expectation of a probabilistic neural network as a
predictor by itself, focusing on the aggregation of binary activated neural
networks with normal distributions over real-valued weights. Our work leverages
a recent analysis derived from the PAC-Bayesian framework that derives tight
generalization bounds and learning procedures for the expected output value of
such an aggregation, which is given by an analytical expression. While the
combinatorial nature of the latter has been circumvented by approximations in
previous works, we show that the exact computation remains tractable for deep
but narrow neural networks, thanks to a dynamic programming approach. This
leads us to a peculiar bound minimization learning algorithm for binary
activated neural networks, where the forward pass propagates probabilities over
representations instead of activation values. A stochastic counterpart that
scales to wide architectures is proposed
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