Simulations of laser locking to a LISA arm

We present detailed numerical simulations of a laser phase stabilization scheme for LISA, where both lasers emitting along one arm are locked to each other. Including the standard secondary noises and spacecraft motions that approximately mimic LISA's orbit, we verify that very stable laser phases can be obtained, and that time delay interferometry can be used to remove the laser phase noise from measurements of gravitational wave strains. Most importantly, we show that this locking scheme can provide significant simplifications over LISA's baseline design in the implementation of time delay interferometry.Comment: 7 figures, 8 page

The triggering of electromagnetic observations by gravitational wave events

The prospects for the observation of electromagnetic emissions by gravitational wave sources first detected using a network of interferometers are discussed. Various emission mechanisms and detection techniques for compact binary inspirals are studied to show that the pointing ability of gravitational wave observatories and the efficacy of electromagnetic detectors can be combined to predict that counterpart detections are improbable for the Initial interferometers, possible with Advanced LIGO detectors, and likely with an Advanced detector in Europe. Results from a new position estimation algorithm for unmodeled sources are also presented, and are discussed in the context of the observation of counterparts to burst sources of gravitational radiation

Prospects for the detection of electromagnetic counterparts to gravitational wave events

Various models for electromagnetic emissions correlated with the gravitational wave signals expected to be detectable by the current and planned gravitational wave detectors are studied. The position error on the location of a gravitational wave source is estimated, and is used to show that it could be possible to observe the electromagnetic counterparts to neutron star-neutron star or neutron star-black hole binary coalescences detected with the Advanced LIGO and the Virgo detectors.Comment: 5 pages, 1 table, 1 figur

Power filters for gravitational wave bursts: network operation for source position estimation

A method is presented to generalize the power detectors for short bursts of gravitational waves that have been developed for single interferometers so that they can optimally process data from a network of interferometers. The performances of this method for the estimation of the position of the source are studied using numerical simulations.Comment: To appear in the proceedings of GWDAW 2002 (Classical and Quantum Gravity, Special issue

Using confocal microscopy and digital image correlation to measure local strains around a chip corner and a crack front

Abstract: In a flip chip package, the chip corner areas which are embedded in the underfill material are often critical to the damage initiation, since a stress concentration usually exists at these locations. A high level of stress concentration often promotes crack initiation from the chip corner. In order to better understand the local deformation around chip corners and crack tips, a method based on laser scanning confocal microscopy combined with the digital image correlation (confocal-DIC) was developed to measure local strain directly in deformed, transparent objects. A transparent epoxy resin with alumina particle fillers was used in four different types of samples, which were fabricated for the purpose of validation. A non-constrained sample and a thin-layer sample were used to verify the isotropic thermal expansion and the strain gradients with respect to the depth, respectively. Results from both samples were in good agreements with the calculation from the coefficient of thermal expansion (CTE) and FEM simulations. Furthermore, the confocal-DIC technique was applied to measure the strain distribution near the chip corner area of a third sample replicating the geometry of a flip chip package. The measured maximum first principal strain was located at the chip corner, reaching 0.9 % at 60 °C, in a good agreement with the simulation results. The strain in front of the crack tip was also evaluated by a three-point bending test in a fourth test sample. The measured maximum strain was 5.8±0.7 %, corresponding to a relative error of only about 5 % compared to simulations for a round crack tip configuration. The averaging used in DIC lowers its spatial resolution and makes it difficult to capture higher strain gradients in small regions. However, the confocal-DIC approach appears to be able to provide reasonable results for evaluating the maximum strain and the full field strain distribution in tri-dimensional volumes with geometries, materials and dimensions which are very similar to those of actual flip chip microelectronic packages

Méthodologie d’évaluation des principaux impacts sur la population de l’augmentation du trafic ferroviaire lors de l’implantation d’un pôle logistique majeur

RÉSUMÉ : Le transport de marchandises par conteneurs est en plein essor depuis quelques années. Grâce à cette unité de transport, l’intermodalité entre le bateau, le train et le camion est plus efficace et permet d’offrir un service continu, fiable, sécuritaire, rapide et à moindre coût. Cette tendance a pour cause d’augmenter l’affluence de conteneurs dans les terminaux intermodaux qui se situent souvent dans les régions urbaines. Au fil du temps, les terminaux sont soumis à des contraintes de capacité face à la congestion et la densité des populations urbaines. En réponse à ce problème, de nouveaux pôles logistiques sont déployés vers les régions rurales où il y a moins d’encombrement face au développement d’infrastructures et au transport de marchandises. C’est le cas, entre autres, du nouveau terminal du port de Montréal à Contrecœur qui cherche à répondre à la demande accrue du transport par conteneurs face à des installations qui approche bientôt la pleine capacité. L’emplacement de ces futurs pôles logistiques concorde souvent avec les réseaux routiers et ferroviaires déjà en place permettant ainsi une interconnexion efficace vers les différentes régions à desservir. L’utilisation faite du transport ferroviaire et routier repose sur des facteurs comme la destination, la nature du produit, le risque et le coût. Effectivement, les économies d’échelles possibles grâce à l’utilisation d’un train de marchandises intermodal à double étages sont non négligeables pour les expéditeurs. Cette relation entre les deux modes de transport devient importante lorsque l’on considère les différentes conséquences de l’augmentation du transport de marchandises sur une région donnée. En fait, la capacité opérationnelle d’un pôle logistique et la proportion utilisée entre les modes de transport toucheront directement la population environnante. Les impacts de l’augmentation du transport de marchandises sur le réseau ferroviaire auront des conséquences différentes sur la population. Tout d’abord, l’augmentation de passages de trains sur une voie ferrée engendre de la congestion aux passages à niveau selon l’horaire, la vitesse et la longueur du train. Tout dépendant du débit de circulation aux passages à niveau, le temps de blocage peut avoir pour conséquence de créer des files d’attente importante sur réseau. La hausse des niveaux de bruit et vibrations affectera également la population à proximité des voies ferrées pouvant ainsi provoquer des perturbations du sommeil et du dérangement. Par ailleurs, le niveau de sécurité de la population est affecté par le transport de matières dangereuses et l’efficacité des services d’urgence. Effectivement, le blocage des passages à niveau peut créer des problématiques lors d’opérations des services d’urgence. Les populations aux abords des futurs pôles logistiques s’inquiètent de ces impacts possibles et il est important de considérer ses préoccupations face au succès de projets d’envergure. L’objectif de ce mémoire est de mieux comprendre ces impacts et de les évaluer afin d’obtenir des résultats pertinents face à l’implantation de nouveaux pôles logistiques majeurs. Il présente une méthodologie d’analyse des impacts sur la population face à l’augmentation d’affluence de trains sur le réseau ferroviaire par l’intégration cartographique de données, la prévision des niveaux d’activités et le calcul d’impacts sur la population concernant la circulation routière, le bruit et les vibrations et la sécurité. Finalement, un outil Excel interactif permet de déterminer le temps de passage des trains au passage à niveau, son impact sur la circulation et le nombre de personnes affectées par un certain niveau de bruit. Ce mémoire analyse les enjeux importants face à l’acceptabilité sociale des projets de pôles logistiques d’envergure en assurant une intégration positive du projet dans la communauté. Le fait de connaître les impacts probables avant la mise en opération des installations permet ainsi de s’ajuster et diminuer les effets néfastes possibles. La méthodologie permet également de justifier l’implantation de mesures d’atténuation comme l’abolition du sifflement d’un train, la pause de barrières aux passages à niveau ou même la construction d’un viaduc. Il contribue également à la sécurité de la communauté en évaluant le niveau d’efficacité des services d’urgence en identifiant les différentes problématiques liées aux passages des trains. Bref, les impacts sur la circulation dépendent fortement de la vitesse du train et du débit de circulation au passage à niveau. Par exemple, à une intersection achalandée, le délai d’attente moyen par véhicule peut atteindre 5 minutes et impacter jusqu’à 150 véhicules si un train circule à 30 km/h. Cependant, si celui-ci circulait à une plus haute vitesse, il engendrerait un plus haut niveau de bruit. Il existe donc une contradiction entre les impacts sur la circulation et les impacts sur le bruit difficilement acceptable par les communautés. En fait, le bruit d’un train de marchandises circulant à 60 km/h provoquerait un niveau de bruit de 43 dB(A) pour une personne à 300 mètres de la voie ferrée. À ce niveau sonore, c’est souvent entre 1% et 2,5% d’une population qui est affectée par le bruit en provenance du train selon la région d’analyse. Par ailleurs, la couverture des services d’incendie est touchée par le passage des trains et la cohésion entre les compagnies ferroviaires et les municipalités est primordiale. Par exemple, dans notre étude de cas, une des municipalités voit 55 % de sa population isolée du poste d’incendie en cas de blocage majeur de la voie ferrée. Finalement, le transport de conteneurs ne représente pas de risques importants concernant les matières dangereuses et engendre un niveau de vibration plutôt faible à plus de 50 mètres de la voie ferrée.----------ABSTRACT : Transportation of goods by containers has been booming in recent years. Thanks to this transport unit, the intermodality between boats, trains and trucks is more efficient and offers a continuous, reliable, safe, fast and inexpensive service. This trend has increased the number of containers in intermodal terminals that are often located in urban areas. Over time, terminals are subject to capacity constraints regarding congestion and density of urban populations. In response to this problem, new logistics clusters are being deployed to rural areas where there is less congestion for infrastructure development and freight transportation. This is the case for the new terminal of Montreal Port Authority in Contrecoeur, which is seeking to meet the increased demand for containers transport against facilities that are near full capacity. The location of these future logistics clusters often coincides with the existing road and rail networks, thus allowing efficient interconnection to the different regions to be served. The use of rail and road transport is based on factors such as the destination, product nature, risk and cost. Indeed, the economies of scale possible through the use of double-stack rail transportation are not negligible for shippers. This relationship between the two modes of transport becomes important when one considers the different impacts of an increase in freight transport over a given region. In fact, the operational capacity of a logistics hub and the proportion used between modes of transport will directly affect the surrounding population. The impacts of increasing freight transport on the rail network will have different consequences for the population. First, the increase in train crossings on a railway leads to road congestion according to the timetable, speed and length of the train. Depending on the traffic flow at railroad grade crossings, blocking time can result in significant queues on the network. Higher levels of noise and vibration will also affect the population close to the railways, which can cause disturbances in sleep and annoyance. Also, the population safety is affected by the transport of hazardous materials and the effectiveness of emergency services. Indeed, the blockage of railroad grade crossings can create problems during emergency services’ operation. The populations around the future logistics centers are worried about these possible impacts and it’s important to consider their concerns for the success of major projects. This helps understand these impacts and evaluate them in order to obtain relevant results regarding the implementation of major new logistics clusters. It presents a methodology for analyzing population impacts facing an increase in the number of trains on the rail network through cartographic integration of data, prediction of activity levels and calculation of impacts on the population concerning traffic, noise, vibration and safety. Finally, an interactive Excel tool is used to determine the transit time of trains at railroad grade crossings, its impact on traffic and the number of people affected according to a certain level of noise. This thesis analyzes the important issues regarding social acceptability of large-scale logistics hub projects by ensuring a positive integration into the community. Being aware of the possible impacts before the terminal starts operating, makes it possible to adjust and reduce the possible adverse effects. The methodology also allows justifications on mitigation measures implementation such as the abolition of a train’s whistle, the addition of barriers at railroad grade crossings or even the construction of a viaduct. It also contributes to the safety of the community by assessing the level of effectiveness of emergency services by identifying the different problems related to the passage of trains. In short, traffic impacts are highly dependent on train speed and traffic flow at the railroad grade crossing. For example, at a busy intersection, the average waiting time per vehicle can reach 5 minutes and impact up to 150 vehicles if a train travels at 30 km/h. However, if it was traveling at a higher speed, it would generate a higher level of noise. There is thus a contradiction between the impacts on traffic and the impacts on noise that is hardly accepted by communities. In fact, a freight train traveling at 60 km/h would cause a noise level of 43 dB (A) for a person standing 300 meters from the track. At this level, it is often between 1% and 2.5% of a population that is affected by noise from the train depending on the region of analysis. Moreover, the coverage of fire departments is affected by the passage of trains and the cohesion between railway companies and municipalities is crucial. For example, in our case study, one of the municipalities sees 55% of its population isolated from the fire station in the event of a major railway blockage. Finally, transportation of containers does not pose a significant risk regarding hazardous materials and generates a rather low level of vibration at more than 50 meters from the track

Morphosyntactic development and severe parental neglect in 4-year-old French-speaking children : ELLAN Study

Language is the most frequently compromised area of development in English-speaking neglected children, particularly the morphosyntactic component of language. This is very worrisome given its central role in academic success and social participation. No previous study has examined the morphosyntactic skills of French-speaking neglected children, despite the morphological richness of French. This study aimed to fill this gap. Forty-four neglected (mean age ¼ 48.32 months, SD ¼ 0.45) and 92 non-neglected (mean age ¼ 48.07 months, SD ¼ 0.24) French-speaking children participated. Measures of morphosyntactic skills were derived from a sample of spontaneous language collected during standardized semistructured play and analyzed using Systematic Analysis of Language Transcripts software (2012) . Four morphosyntactic indicators were compared using analyses of variance and Kolmogorov–Smirnov tests: the mean length of utterances (MLU), verbal inflections, word-level errors, and omission errors. The results indicate that 25.6% of the neglected children presented clinically significant morphosyntactic difficulties, as evidenced by a significantly shorter MLU (M ¼ 5.60, SD ¼ 1.13; M ¼ 6.90, SD ¼ 1.30), fewer verbal inflections, and more frequent word omission errors compared to their non-neglected peers. The results confirm that French-speaking neglected children present many morphosyntactic difficulties. This study argues for sustained speech–language services for these children

Long mRNAs coding for yeast mitochondrial proteins of prokaryotic origin preferentially localize to the vicinity of mitochondria

BACKGROUND: Subcellular messenger RNA localization is important in most eukaryotic cells, even in unicellular organisms like yeast for which this process has been underestimated. Microarrays are rarely used to study subcellular mRNA localization at whole-genome level, but can be adapted to that purpose. This work focuses on studying the repartition of yeast nuclear transcripts encoding mitochondrial proteins between free cytosolic polysomes and polysomes bound to the mitochondrial outer membrane. RESULTS: Combining biochemical fractionations with oligonucleotide array analyses permits clustering of genes on the basis of the subcellular sites of their mRNA translation. A large fraction of yeast nuclear transcripts known to encode mitochondrial proteins is found in mitochondrial outer-membrane-bound fractions. These results confirm and extend a previous analysis conducted with partial genomic microarrays. Interesting statistical relations among mRNA localization, gene origin and mRNA lengths were found: longer and older mRNAs are more prone to be localized to the vicinity of mitochondria. These observations are included in a refined model of mitochondrial protein import. CONCLUSIONS: Mitochondrial biogenesis requires concerted expression of the many genes whose products make up the organelle. In the absence of any clear transcriptional program, coordinated mRNA localization could be an important element of the time-course of organelle construction. We have built a 'MitoChip' localization database from our results which allows us to identify interesting genes whose mRNA localization might be essential for mitochondrial biogenesis in most eukaryotic cells. Moreover, many components of the experimental and data-analysis strategy implemented here are of general relevance in global transcription studies

Optimal generalization of power filters for gravitational wave bursts, from single to multiple detectors

Searches for gravitational wave signals which do not have a precise model describing the shape of their waveforms are often performed using power detectors based on a quadratic form of the data. A new, optimal method of generalizing these power detectors so that they operate coherently over a network of interferometers is presented. Such a mode of operation is useful in obtaining better detection efficiencies, and better estimates of the position of the source of the gravitational wave signal. Numerical simulations based on a realistic, computationally efficient hierarchical implementation of the method are used to characterize its efficiency, for detection and for position estimation. The method is shown to be more efficient at detecting signals than an incoherent approach based on coincidences between lists of events. It is also shown to be capable of locating the position of the source.Comment: 16 pages, 5 figure