Inflation and Relative Price Dispersion in Canada: An Empirical Assessment

The authors investigate empirically the relationship between different aspects of inflation and relative price dispersion in Canada using a Markov regime-switching Phillips curve. They examine three theories that explain movements in relative price dispersion: the signal extraction model, the extension of the signal extraction model, and the menu cost model. The authors show that expected inflation, which is captured by the menu cost model, is the aspect of inflation that is most closely associated with relative price dispersion. Furthermore, this result seems robust to different specifications. The authors, however, cannot completely discard inflation uncertainty (the signal extraction model), especially when using core inflation. They also observe a strong asymmetry regarding the impact of positive and negative unexpected inflation on relative price dispersion using total inflation, but this asymmetry is not observed for core inflation. This suggests that the strong asymmetry arises mainly from the presence of components typically associated with supply shocks, and not from the presence of downward nominal rigidities, as Aarstol (1999) proposes, following Ball and Mankiw (1992a,b).Inflation and prices

Y a-t-il eu surinvestissement au Canada durant la seconde moitié des années 1990?

This study on overinvestment differs from the existing literature in that investment in machinery and equipment is modelled as a structural vector autoregression with identification achieved by imposing long-run restrictions, as in Blanchard and Quah (1989). The transitory components obtained from the model suggest the existence of a minor overinvestment in machinery and equipment of less than 5 per cent in 2000, despite a significant overevaluation of the stock market.Domestic demand and components

CRISPR-Cas : an efficient tool for genome engineering of virulent bacteriophages

Bacteriophages are now widely recognized as major players in a wide variety of ecosystems. Novel genes are often identified in newly isolated phages as well as in environmental metavirome studies. Most of these novel viral genes have unknown functions but appear to be coding for small, non-structural proteins. To understand their biological role, very efficient genetic tools are required to modify them, especially in the genome of virulent phages. We first show that specific point mutations and large deletions can be engineered in the genome of the virulent phage 2972 using the Streptococcus thermophilus CRISPR-Cas Type II-A system as a selective pressure to increase recombination efficiencies. Of significance, all the plaques tested contained recombinant phages with the desired mutation. Furthermore, we show that the CRISPR-Cas engineering system can be used to efficiently introduce a functional methyltransferase gene into a virulent phage genome. Finally, synthetic CRISPR bacteriophage insensitive mutants were constructed by cloning a spacer-repeat unit in a low-copy vector illustrating the possibility to target multiple regions of the phage genome. Taken together, this data shows that the CRISPR-Cas system is an efficient and adaptable tool for editing the otherwise intractable genomes of virulent phages and to better understand phage-host interactions

Targeting active cancer cells with smart bullets

Paul Ehrlich's 'magic bullet' concept has stimulated research for therapeutic agents with the capability to go straight to their intended targets. The 'magic bullet' concept is still considered the ultimate approach to maximize the therapeutic effects of a given therapeutic agent without affecting nontargeted tissues. But so far, there has never been a therapeutic agent or a delivery system that goes straight to the target in the body, and no approach has provided anything better than just a few percents of the total administered dose reaching the intended target sites. But engineering principles can transform systematically circulating vectors that so far were based primarily on physical characteristics and biochemical principles alone, as smart therapeutic agents with the required propulsion-navigation-homing capabilities to enable them to go straight to their intended targets

Étude numérique d'un écoulement diphasique critique dans un convergent-divergent

Cette thèse a pour but de présenter les travaux liés à l'étude numérique des écoulements critiques diphasiques dans la tuyère primaire d'un éjecteur utilisé pour améliorer le rendement d'un cycle de réfrigération. En premier lieu, les bases d'un modèle d'écoulement multiphasique ainsi que les termes de source associés sont présentés. Les développements entourant les points singuliers ainsi que les conditions critiques sont également présentés. Deux schémas numériques unidimensionnels sont proposés pour l'étude d'un écoulement critique diphasique particulaire. Les comparaisons des flux massiques critiques ainsi que des profils de pression numériques et expérimentaux montrent que le modèle représente bien l'évolution de l'écoulement diphasique. L'existence d'un point critique situé à un endroit différent du col géométrique a été vérifiée. L'étude numérique présente également une validation des conditions critiques utilisées ainsi que les effets des déséquilibres sur la position du point critique et sur l'écoulement. Des travaux supplémentaires sont cependant requis pour mieux comprendre le phénomène entourant les chocs en écoulements diphasiques et pour accroître la plage de taux de vide couverte par les schémas numériques

Combining Pulsed and DC Gradients in a Clinical MRI-Based Microrobotic Platform to Guide Therapeutic Magnetic Agents in the Vascular Network

Magnetic Resonance Navigation (MRN) relies on the use of an upgraded clinical Magnetic Resonance Imaging (MRI) scanner to navigate therapeutic, imaging, or diagnostic magnetic micro-agents in the vascular network. Although the high homogeneous field in the tunnel of the MRI scanner increases the magnetization of the navigable agents towards full saturation, the magnetic gradients superposed on such a high homogeneous field, generated by the Imaging Gradient Coils (IGC) typically used for MR-image slice selection, allow the induction of pulling forces to steer such agents in the targeted branches at the vessel's bifurcations. However, increasing the magnitude of such gradients leads to a significant decrease of the duty cycle, leading to a substantial reduction of the effective steering force being applied. To increase such a duty cycle, a Steering Gradient Coils (SGC) assembly capable of higher magnitudes while maintaining a 100% duty cycle can be installed at the cost of a much slower slew rate. Here, the use and the potential effectiveness of IGC and/or SGC for guiding such agents are briefly investigated on the basis of known specifications and experimental data

Switching between magnetotactic and aerotactic displacement controls to enhance the efficacy of MC-1 magneto-aerotactic bacteria as cancer-fighting nanorobots

The delivery of drug molecules to tumor hypoxic areas could yield optimal therapeutic outcomes. This suggests that effective cancer-fighting micro- or nanorobots would require more integrated functionalities than just the development of directional propelling constructs which have so far been the main general emphasis in medical micro- and nanorobotic research. Development of artificial agents that would be most effective in targeting hypoxic regions may prove to be a very challenging task considering present technological constraints. Self-propelled, sensory-based and directionally-controlled agents in the form of Magnetotactic Bacteria (MTB) of the MC-1 strain have been investigated as effective therapeutic nanorobots in cancer therapy. Following computer-based magnetotactic guidance to reach the tumor area, the microaerophilic response of drug-loaded MC-1 cells could be exploited in the tumoral interstitial fluid microenvironments. Accordingly, their swimming paths would be guided by a decreasing oxygen concentration towards the hypoxic regions. However, the implementation of such a targeting strategy calls for a method to switch from a computer-assisted magnetotactic displacement control to an autonomous aerotactic displacement control. In this way, the MC-1 cells will navigate to tumoral regions and, once there, target hypoxic areas through their microaerophilic behavior. Here we show not only how the magnitude of the magnetic field can be used for this purpose but how the findings could help determine the specifications of a future compatible interventional platform within known technological and medical constraints

NanoWalker: a fully autonomous highly integrated miniature robot for nanoscale measurements

The aim of this project is to develop the smallest and most sophisticated wireless fully autonomous instrumented robot capable of subatomic movements. The robot named 'NanoWalker' should bring a new paradigm in the way instruments are built while providing a sophisticated platform for a new range of applications. The project involves primarily the investigation of a new legged locomotion based on piezo-actuators with advanced micro-assembly techniques applied to complex embedded electronic systems; the development of new miniature instruments, micro-manipulators, integrated behavior for controlling, searching and scanning at the atomic scale; and the development of a subatomic navigation system. Besides all the new technologies and techniques that we intend to develop and which will be applicable to many areas and systems, the NanoWalker should provide a suitable yet more flexible and powerful platform compared to traditional macro-scaled instruments. It is anticipated that this new form of highly integrated autonomous microsystem will be used as the main building block for a new generation of measurement and inspection systems. In this paper, the main components of the NanoWalker are briefly described.Seaver Institut

Enabling automated magnetic resonance imaging-based targeting assessment during dipole field navigation

The magnetic navigation of drugs in the vascular network promises to increase the efficacy and reduce the secondary toxicity of cancer treatments by targeting tumors directly. Recently, dipole field navigation (DFN) was proposed as the first method achieving both high field and high navigation gradient strengths for whole-body interventions in deep tissues. This is achieved by introducing large ferromagnetic cores around the patient inside a magnetic resonance imaging (MRI) scanner. However, doing so distorts the static field inside the scanner, which prevents imaging during the intervention. This limitation constrains DFN to open-loop navigation, thus exposing the risk of a harmful toxicity in case of a navigation failure. Here, we are interested in periodically assessing drug targeting efficiency using MRI even in the presence of a core. We demonstrate, using a clinical scanner, that it is in fact possible to acquire, in specific regions around a core, images of sufficient quality to perform this task. We show that the core can be moved inside the scanner to a position minimizing the distortion effect in the region of interest for imaging. Moving the core can be done automatically using the gradient coils of the scanner, which then also enables the core to be repositioned to perform navigation to additional targets. The feasibility and potential of the approach are validated in an in vitro experiment demonstrating navigation and assessment at two targets

MULTI-SPECTRAL IMAGE ANALYSIS FOR SKIN PIGMENTATION CLASSIFICATION

International audienceIn this paper, we compare two different approaches for semi- automatic detection of skin hyper-pigmentation on multi- spectral images. These two methods are support vector machine (SVM) and blind source separation. To apply SVM, a dimension reduction method adapted to data classification is proposed. It allows to improve the quality of SVM classification as well as to have reasonable computation time. For the blind source separation approach we show that, using independent component analysis, it is possible to extract a relevant cartography of skin pigmentation