Seismic vulnerability assessment: Methodological elements and applications to the case of Romania

This paper is intended to present some studies undertaken in order to develop a seismic vulnerability estimation system to fit the needs of development of earthquake scenarios and of development of an integrated disaster risk management system for Romania. Methodological aspects are dealt with, in connection with the criteria of categorization of buildings, with the definition of parameters used for characterizing vulnerability, with the setting up of an inventory of buildings and with the calibration of parameters characterizing vulnerability. Action was initiated along the coordinates referred to in connection with the methodological aspects mentioned above. The approach was made, as far as possible, specific to the conditions of Romania. Some data on results obtained to date are presented.seismic vulnerability, vulnerability estimation, earthquake scenarios, categorization of buildings, inventory of buildings, expected earthquake impact

Second order perturbation theory for embedded eigenvalues

We study second order perturbation theory for embedded eigenvalues of an abstract class of self-adjoint operators. Using an extension of the Mourre theory, under assumptions on the regularity of bound states with respect to a conjugate operator, we prove upper semicontinuity of the point spectrum and establish the Fermi Golden Rule criterion. Our results apply to massless Pauli-Fierz Hamiltonians for arbitrary coupling.Comment: 30 pages, 2 figure

Methylation landscape in the genome of higher plants of agronomical interest

In eukaryotic cells the methylation of cytosines in DNA is an essential mechanism which is implied in the dynamic organization of the genome structure, in relation to genes expression. Plant genomes contain a significant proportion and variable according to the species, of sequences which are likely to be methylated during the life of the plant. It is known that the establishment and the maintenance of methylation profiles in both genomic areas and specific sequences constitute a crucial mediator in the modulation of genes expression during development. Recent studies have evidenced the implication of epimutations in the adaptation of plants to their environment particularly in response to biotic and abiotic stresses. Recently, the complete mapping of methylation in the genomes of Arabidopsis thaliana and rice provided invaluable information on the distribution of methylation within genes in relation to their expression. The impact of changes in the methylation profiles on the characters of agronomic importance has not been intensively studied yet, whereas this question takes a considerable importance in the context of an increasing food demand and foreseen global climate changes. The METHYLANDSCAPE project proposes to isolate genomic DNA sequences on the basis of their degree of methylation and to connect the variation of their methylation profiles with, on the one hand, the expression of the corresponding genes and, on the other hand, with environmental or developmental processes. Thus, it should be possible to identify genes which expression is differentially controlled by methylation during development and/or in situation of stress, and likely to have an influence on the agronomic value of the plant. The METHYLANDSCAPE partners thus propose to bring signification advances in plant genomics on four original species, by integrating DNA methylation mapping and the relationship between epigenome and transcriptome, up to the generation of methylation-sensitive markers linked with characters of agronomic importance. (Texte intégral

Cluster magnetic field observations in the magnetosheath: four-point measurements of mirror structures

International audienceThe Cluster spacecraft have returned the first simultaneous four-point measurements of the magnetosheath. We present an analysis of data recorded on 10 November 2000, when the four spacecrafts observed an interval of strong mirrorlike activity. Correlation analysis between spacecraft pairs is used to examine the scale size of the mirror structures in three dimensions. Two examples are presented which suggest that the scale size of mirror structures is ~ 1500?3000 km along the flow direction, and shortest along the magnetopause normal (< 600 km), which, in this case, is approximately perpendicular to both the mean magnetic field and the magnetosheath flow vector. Variations on scales of ~ 750?1000 km are found along the maximum variance direction. The level of correlation in this direction, however, and the time lag observed, are found to be variable. These first results suggest that variations occur on scales of the order of the spacecraft separation ( ~ 1000 km) in at least two directions, but analysis of further examples and a statistical survey of structures observed with different magnetic field orientations and tetrahedral configurations will enable us to describe more fully the size and orientation of mirror structures

On perturbations of Dirac operators with variable magnetic field of constant direction

We carry out the spectral analysis of matrix valued perturbations of 3-dimensional Dirac operators with variable magnetic field of constant direction. Under suitable assumptions on the magnetic field and on the pertubations, we obtain a limiting absorption principle, we prove the absence of singular continuous spectrum in certain intervals and state properties of the point spectrum. Various situations, for example when the magnetic field is constant, periodic or diverging at infinity, are covered. The importance of an internal-type operator (a 2-dimensional Dirac operator) is also revealed in our study. The proofs rely on commutator methods.Comment: 12 page

First simultaneous observations of flux transfer events at the high-latitude magnetopause by the cluster spacecraft and pulsed radar signatures in the conjugate ionosphere by the CUTLASS and EISCAT radars

Cluster magnetic field data are studied during an outbound pass through the post-noon high-latitude magnetopause region on 14 February 2001. The onset of several minute perturbations in the magnetospheric field was observed in conjunction with a southward turn of the interplanetary magnetic field observed upstream by the ACE spacecraft and lagged to the subsolar magnetopause. These perturbations culminated in the observation of four clear magnetospheric flux transfer events (FTEs) adjacent to the magnetopause, together with a highly-structured magnetopause boundary layer containing related field features. Furthermore, clear FTEs were observed later in the magnetosheath. The magnetospheric FTEs were of essentially the same form as the original “flux erosion events” observed in HEOS-2 data at a similar location and under similar interplanetary conditions by Haerendel et al. (1978). We show that the nature of the magnetic perturbations in these events is consistent with the formation of open flux tubes connected to the northern polar ionosphere via pulsed reconnection in the dusk sector magnetopause. The magnetic footprint of the Cluster spacecraft during the boundary passage is shown to map centrally within the fields-of-view of the CUTLASS SuperDARN radars, and to pass across the field-aligned beam of the EISCAT Svalbard radar (ESR) system. It is shown that both the ionospheric flow and the backscatter power in the CUTLASS data pulse are in synchrony with the magnetospheric FTEs and boundary layer structures at the latitude of the Cluster footprint. These flow and power features are subsequently found to propagate poleward, forming classic “pulsed ionospheric flow” and “poleward-moving radar auroral form” structures at higher latitudes. The combined Cluster-CUTLASS observations thus represent a direct demonstration of the coupling of momentum and energy into the magnetosphere-ionosphere system via pulsed magnetopause reconnection. The ESR observations also reveal the nature of the structured and variable polar ionosphere produced by the structured and time-varying precipitation and flow

Substorm observations in the early morning sector with Equator-S and Geotail

International audienceData from Equator-S and Geotail are used to study the dynamics of the plasma sheet observed during a substorm with multiple intensifications on 25 April 1998, when both spacecraft were located in the early morning sector (03?04 MLT) at a radial distance of 10?11 RE. In association with the onset of a poleward expansion of the aurora and the westward electrojet in the premidnight and midnight sector, both satellites in the morning sector observed plasma sheet thinning and changes toward a more tail-like field configuration. During the subsequent poleward expansion in a wider local time sector (20?04 MLT), on the other hand, the magnetic field configuration at both satellites changed into a more dipolar configuration and both satellites encountered again the hot plasma sheet. High-speed plasma flows with velocities of up to 600 km/s and lasting 2?5 min were observed in the plasma sheet and near its boundary during this plasma sheet expansion. These high-speed flows included significant dawn-dusk flows and had a shear structure. They may have been produced by an induced electric field at the local dipolarization region and/or by an enhanced pressure gradient associated with the injection in the midnight plasma sheet

Single-molecule visualization of Saccharomyces cerevisiae leading-strand synthesis reveals dynamic interaction between MTC and the replisome

The replisome, the multiprotein system responsible for genome duplication, is a highly dynamic complex displaying a large number of different enzyme activities. Recently, the Saccharomyces cerevisiae minimal replication reaction has been successfully reconstituted in vitro. This provided an opportunity to uncover the enzymatic activities of many of the components in a eukaryotic system. Their dynamic behavior and interactions in the context of the replisome, however, remain unclear. We use a tethered-bead assay to provide real-time visualization of leading-strand synthesis by the S. cerevisiae replisome at the single-molecule level. The minimal reconstituted leading-strand replisome requires 24 proteins, forming the CMG helicase, the Pol e DNA polymerase, the RFC clamp loader, the PCNA sliding clamp, and the RPA single-stranded DNA binding protein. We observe rates and product lengths similar to those obtained from ensemble biochemical experiments. At the single-molecule level, we probe the behavior of two components of the replication progression complex and characterize their interaction with active leading-strand replisomes. The Minichromosome maintenance protein 10 (Mcm10), an important player in CMG activation, increases the number of productive replication events in our assay. Furthermore, we show that the fork protection complex Mrc1-Tof1-Csm3 (MTC) enhances the rate of the leading-strand replisome threefold. The introduction of periods of fast replication by MTC leads to an average rate enhancement of a factor of 2, similar to observations in cellular studies. We observe that the MTC complex acts in a dynamic fashion with the moving replisome, leading to alternating phases of slow and fast replication

Genetic diversity analyses of seven Romanian pig populations based on 10 microsatellites

Abstract Genotype data from 10 microsatellites were used to assess genetic diversity and relationships among 7 swine breeds: Synthetic Line-345 Peris, Synthetic Line LSP-2000, Pietrai