The gauge invariant currents of the Maxwellian field

We show that a conserved current for the Maxwellian field, which is invariant under the gauge group of that field, is the sum of two currents Ф+T, where Ф corresponds to a Poincare symmetry of the field, and T is a topological form that is conserved under every dynamics.

Postnatal development of glutamatergic receptormediated excitatory postsynaptic currents and their modulations by ach and dopamine in nucleus accumbens

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Molecular basis of native inward rectifier currents : role of Kir2 subunits

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Postnatal development of glutamatergic receptormediated excitatory postsynaptic currents and their modulations by ach and dopamine in nucleus accumbens

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Molecular basis of native inward rectifier currents : role of Kir2 subunits

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

TRPV2 Channels Contribute to Stretch-Activated Cation Currents and Myogenic Constriction in Retinal Arterioles

Purpose: Activation of the transient receptor potential channels, TRPC6, TRPM4, and TRPP1 (PKD2), has been shown to contribute to the myogenic constriction of cerebral arteries. In the present study we sought to determine the potential role of various mechanosensitive TRP channels to myogenic signaling in arterioles of the rat retina.

Methods: Rat retinal arterioles were isolated for RT-PCR, Fura-2 Ca2+ microfluorimetry, patch-clamp electrophysiology, and pressure myography studies. In some experiments, confocal immunolabeling of wholemount preparations was used to examine the localization of specific mechanosensitive TRP channels in retinal vascular smooth muscle cells (VSMCs).

Results: Reverse transcription-polymerase chain reaction analysis demonstrated mRNA expression for TRPC1, M7, V1, V2, V4, and P1, but not TRPC6 or M4, in isolated retinal arterioles. Immunolabeling revealed plasma membrane, cytosolic and nuclear expression of TRPC1, M7, V1, V2, V4, and P1 in retinal VSMCs. Hypoosmotic stretch-induced Ca2+ influx in retinal VSMCs was reversed by the TRPV2 inhibitor tranilast and the nonselective TRPP1/V2 antagonist amiloride. Inhibitors of TRPC1, M7, V1, and V4 had no effect. Hypoosmotic stretch-activated cation currents were similar in Na+ and Cs+ containing solutions suggesting no contribution by TRPP1 channels. Direct plasma membrane stretch triggered cation current activity that was blocked by tranilast and specific TRPV2 pore-blocking antibodies and mimicked by the TRPV2 activator, Δ9-tetrahydrocannabinol. Preincubation of retinal arterioles with TRPV2 blocking antibodies prevented the development of myogenic tone.

Conclusions: Our results suggest that retinal VSMCs express a range of mechanosensitive TRP channels, but only TRPV2 appears to contribute to myogenic signaling in this vascular bed.

Potential of incorporating ocean currents in fishing vessels

The fishing sector has been suffering a strong setback, with reduction in fishing stocks and more recently with the reduction of the fishing fleet. One of the most important factors for this decrease, is related to the continuous difficulty to find fish with quality and quantity, allowing the sector work constantly all year long. However other factors are affecting negatively the fishing sector, in particular the huge maintenance costs of the ships and the high diary costs that are necessary for daily work of each vessel. One of the main costs associated with daily work, is the fuel consumption. As an example, one boat with 30 meters working around 17 hours every day, consumes 2500 liters of fuel/day. This value is very high taking into account the productivity of the sector. Supporting this premise was developed a project with the aim of reducing fuel consumption in fishing vessels. The project calls “ShipTrack” and aims the use of forecasts of ocean currents in the routes of the ships. The objective involves the use of ocean currents in favor, and avoiding ocean currents against, taking into account the course of the ship, in order to reduce fuel consumption and increase the ship speed. The methodology used underwent the creation of specific Software, in order to optimize routes, taking into account the forecasts of the ocean currents. These forecasts are performed using numerical modelling, methodology that become more and more important in all communities, because through the modeling, it can be analyzed, verified and predicted important phenomena to all the terrestrial ecosystem. The objective was the creation of Software, however its development was not completed, so it was necessary a new approach in order to verify the influence of the ocean currents in the navigation of the fishing ship "Cruz de Malta". In this new approach, and during the various ship routes it was gathering a constant information about the instant speed, instantaneous fuel consumption, the state of the ocean currents along the course of the ship, among other factors. After 4 sea travels and many routes analyzed, it was possible to verify the influence of the ocean currents in the Ship speed and in fuel consumption. For example, in many stages of the sea travels it was possible to verify an increase in speed in zones where the ocean currents are in favor to the ships movements. This incorporation of new data inside the fishing industry, was seen positively by his players, which encourages new developments in this industry.

Study and analysis of the waves and currents interaction phenomena

Interaction of ocean waves, currents and sea bed roughness is a complicated phenomena in fluid dynamic. This paper will describe the governing equations of motions of this phenomena in viscous and nonviscous conditions as well as study and analysis the experimental results of sets of physical models on waves, currents and artificial roughness, and consists of three parts: First, by establishing some typical patterns of roughness, the effects of sea bed roughness on a uniform current has been studied, as well as the manning coefficient of each type is reviewed to find the critical situation due to different arrangement. Second, the effect of roughness on wave parameters changes, such as wave height, wave length, and wave dispersion equations have been studied, third, superimposing, the waves + current + roughness patterns established in a flume, equipped with waves + currents generator, in this stage different analysis has been done to find the governing dimensionless numbers, and present the numbers to define the contortions and formulations of this phenomena. First step of the model is verified by the so called Chinese method, and the Second step by the Kamphius (1975), and third step by the van Rijn (1990) , and Brevik and Ass ( 1980), and in all cases reasonable agreements have been obtained. Finally new dimensionless parameters presented for this complicated phenomena.

DopSCAT: A mission concept for simultaneous measurements of marine winds and surface currents

A radar scatterometer operates by transmitting a pulse of microwave energy toward the ocean's surface and measuring the normalized (per-unit-surface) radar backscatter coefficient (σ°). The primary application of scatterometry is the measurement of near-surface ocean winds. By combining σ° measurements from different azimuth angles, the 10 m vector wind can be determined through a Geophysical Model Function (GMF), which relates wind and backscatter. This paper proposes a mission concept for the measurement of both oceanic winds and surface currents, which makes full use of earlier C-band radar remote sensing experience. For the determination of ocean currents, in particular, the novel idea of using two chirps of opposite slope is introduced. The fundamental processing steps required to retrieve surface currents are given together with their associated accuracies. A detailed description of the mission proposal and comparisons between real and retrieved surface currents are presented. The proposed ocean Doppler scatterometer can be used to generate global surface ocean current maps with accuracies better than 0.2 m/s at a spatial resolution better than 25 km (i.e., 12.5 km spatial sampling) on a daily basis. These maps will allow gaining some insights on the upper ocean mesoscale dynamics. The work lies at a frontier, given that the present inability to measure ocean currents from space in a consistent and synoptic manner represents one of the greatest weaknesses in ocean remote sensing.