Autonomic Role and Mission Allocation Framework for Wireless Sensor Networks.

Pervasive applications incorporate physical components that are exposed to everyday use and a large number of conditions and external factors that can lead to faults and failures. It is also possible that application requirements change during deployment and the network needs to adapt to a new context. Consequently, pervasive systems must be capable to autonomically adapt to changing conditions without involving users becoming a transparent asset in the environment. In this paper, we present an autonomic mechanism for initial task assignment in sensor networks, an NP-hard problem. We also study on-line adaptation of the original deployment which considers real-time metrics for maximising utility and lifetime of applications and smooth service degradation in the face of component failures. © 2011 IEEE

Phase diagram of YBa2_2Cu3_3O7−y_{7-y} at T<<Tc_c based on Cu(2) transverse nuclear relaxation

Two maxima in transverse relaxation rate of Cu(2) nuclei in YBa$_2$Cu$_3$O$_{7-y}$ are observed, at T = 35 K and T = 47 K. Comparison of the $^{63}$Cu(2) and $^{65}$Cu(2) rates at T = 47 K indicates the magnetic character of relaxation. The enhancement at T = 47 K of fluctuating local magnetic fields perpendicular to the CuO$_2$ planes is connected with the critical fluctuations of orbital currents. Maximum at T = 35 K is connected with the appearance of inhomogeneous supeconducting phase. Together with data published to date, our experimental results allow to suggest a qualitatively new phase diagram of the superconducting phase.Comment: 4 LaTEX pages + 3 figures in *.ps forma

Minimising makespan of discrete controllers: a qualitative approach

Qualitative controller synthesis techniques produce controllers that guarantee to achieve a given goal in the presence of an adversarial environment. However, qualitative synthesis only produces one controller out of many possible solutions and typically does not provide support for expressing preferences over other alternatives. In this paper, we thus present a formal approach to reason about preferences qualitatively, restricting attention to makespan of discrete eventbased controllers for reachability goals. Time is reasoned upon symbolically, which relieves the user from providing concrete quantitative measures. In particular, we study the scenario in which durations of individual activities are not known up-front. We first show how controllers can be symbolically and fairly compared by fixing the contingencies. Then, we present an algorithm to produce controllers that are makespan-minimising

Assured and Correct Dynamic Update of Controllers

We present a general approach to specifying correctness criteria for dynamic update and a technique for automatically computing a controller that handles the transition from the old to the new specification, assuring that the system will reach a state in which such a transition can correctly occur. Indeed, using controller synthesis we show how to automatically build a controller that guarantees both progress towards update and safe update.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Dynamic update of discrete event controllers

Discrete event controllers are at the heart of many software systems that require continuous operation. Changing these controllers at runtime to cope with changes in its execution environment or system requirements change is a challenging open problem. In this paper we address the problem of dynamic update of controllers in reactive systems. We present a general approach to specifying correctness criteria for dynamic update and a technique for automatically computing a controller that handles the transition from the old to the new specification, assuring that the system will reach a state in which such a transition can correctly occur and in which the underlying system architecture can reconfigure. Our solution uses discrete event controller synthesis to automatically build a controller that guarantees both progress towards update and safe update

Assured and Correct Dynamic Update of Controllers

We present a general approach to specifying correctness criteria for dynamic update and a technique for automatically computing a controller that handles the transition from the old to the new specification, assuring that the system will reach a state in which such a transition can correctly occur. Indeed, using controller synthesis we show how to automatically build a controller that guarantees both progress towards update and safe update.Sociedad Argentina de Informática e Investigación Operativa (SADIO

752-6 Visualization of Coronary Arteries and Measurement of Coronary Blood Flow with Transthoracic Echocardiography After Intravenous Administration of a New Echocardlographic Contrast Agent

Imagent®US (AF0145, Alliance Pharmaceutical Corp.), a new hemodynamically inert perfluorochemical echocardiographic contrast agent, produces excellent left ventricular and blood pool contrast effect after intravenous administration when imaged with conventional (2-D) ultrasound. We evaluated the potential of Contrast Specific Imaging (Acuson) employing second harmonic principles to further enhance the visualization of structures containing contrast agents. Transthoracic images were obtained during injections of 10–40mg of the agent into the left femoral vein of seven closed chest dogs. Coronary Dopplerflow was simultaneously measured using an intracoronary Doppler wire. No alterations in flow velocities were observed with contrast administration. There was heterogenous opacification of the myocardium following contrast injection: a striking finding was of contrast-enhanced linear, branching structures in the myocardium consistent with coronary vessels. Further exploration of the largest structures (2–3mm diameter) in the region of the basal ventricular septum was technically possible with pulsed wave Doppler in two dogs. A characteristic coronary Doppler flow pattern was observed (Fig 1a). Transthoracic Doppler flow velocities transiently increased after intracoronary adenosine (Fig 1b). The calculated coronary flow reserve ratio was similar to simultaneous intracoronary Doppler measurements.ConclusionsIntramyocardial coronaryvasculature was observed and coronary flow velocites were measured during transthoracic Contrast Specific Imaging with an intravenously administered contrast agent. These findings suggest that noninvasive assessment of coronary blood flow is possible with echocardiographic contrast enhancement

Pericardial Thickness Measured With Transesophageal Echocardiography: Feasibility and Potential Clinical Usefulness

AbstractObjectives. This study assessed the reliability of transesophageal echocardiographic measurements of pericardial thickness and the potential diagnostic usefulness of this technique.Background. Transthoracic echocardiography cannot reliably detect thickened pericardium. The superior resolution achieved with transesophageal echocardiography should allow better pericardial definition.Methods. Pericardial thickness measured at 26 locations in 11 patients with constrictive pericarditis who underwent intraoperative transesophageal echocardiography was compared with pericardial thickness measured with electron beam computed tomography. Intraobserver and interobserver variabilities were determined. Pericardial thickness was then measured in 21 normal subjects. With these values as a guide, two observers reviewed 37 transesophageal echocardiographic studies to determine whether echocardiographic measurement of pericardial thickness could be used to distinguish diseased from normal pericardium.Results. The correlation between echocardiographic and computed tomographic measurements (r ≥ 0.95, SE ≤ 0.06 mm, p < 0.0001) was excellent. The ±2 SD limits of agreement were ±1.0 mm or less for pericardial thickness <5.5 mm and ±2.0 mm or less for the entire range of thicknesses. Intraobserver and interobserver agreements were good. Mean normal pericardial thickness was 1.2 ± 0.8 mm (±2 SD) and did not exceed 2.5 mm. Pericardial thickness ≥3 mm on transesophageal echocardiography was 95% sensitive and 86% specific for the detection of thickened pericardium.Conclusions. Measurement of pericardial thickness with transesophageal echocardiography is reproducible and should be a valuable adjunct in assessing constrictive pericarditis.(J Am Coll Cardiol 1997;29:1317–23