A Run-time System for Efficient Execution of Scientific Workflows on Distributed Environments

Scientific workflow systems have been introduced in response to the demand of researchers from several domains of science who need to process and analyze increasingly larger datasets. The design of these systems is largely based on the observation that data analysis applications can be composed as pipelines or networks of computations on data. In this work, we present a run-time support system that is designed to facilitate this type of computation in distributed computing environments. Our system is optimized for data-intensive workflows, in which efficient management and retrieval of data, coordination of data processing and data movement, and check-pointing of intermediate results are critical and challenging issues. Experimental evaluation of our system shows that linear speedups can be achieved for sophisticated applications, which are implemented as a network of multiple data processing components.     

Recursive subdivision without the convex hull property

Recursive subdivision is a standard technique in computer aided geometric design for intersecting and rendering curves and surfaces. The convergence of recursive subdivision is critical for its effective use. Bézier and B-spline curves and surfaces have recursive subdivision algorithms that are known to converge. We show more generally that if a recursive subdivision algorithm exists for a given curve or surface type, then convergence is guaranteed if the blending functions are continuous, form a partition of unity, and are linearly independent. Thus, convergence of recursive subdivision does not depend on the convex hull property. We also show that even in the absence of the convex hull property, it is possible to define termination tests based on the flatness of control polygons, and to construct intersection algorithms based on recursive subdivision. Examples are given of polynomial curves to which our theorems apply.     

A Multiphase Level Set Framework for Image Segmentation Using the Mumford and Shah Model

We propose a new multiphase level set framework for image segmentation using the Mumford and Shah model, for piecewise constant and piecewise smooth optimal approximations. The proposed method is also a generalization of an active contour model without edges based 2-phase segmentation, developed by the authors earlier in T. Chan and L. Vese (1999. In Scale-Space'99, M. Nilsen et al. (Eds.), LNCS, vol. 1682, pp. 141–151) and T. Chan and L. Vese (2001. IEEE-IP, 10(2):266–277). The multiphase level set formulation is new and of interest on its own: by construction, it automatically avoids the problems of vacuum and overlap; it needs only log n level set functions for n phases in the piecewise constant case; it can represent boundaries with complex topologies, including triple junctions; in the piecewise smooth case, only two level set functions formally suffice to represent any partition, based on The Four-Color Theorem. Finally, we validate the proposed models by numerical results for signal and image denoising and segmentation, implemented using the Osher and Sethian level set method.     

Curved OLED microdisplays

Technical background for CMOS substrate thinning of CEA‐LETI (historically developed for through silicon via technology as well as for more recent activity to provide curved image sensors, for IR as well as for visible spectra) has been applied to realize curved OLED‐based microdisplays. It will be shown that test OLEDs made onto silicon wafers as well as 873 × 500 WVGA, 0.38″ diagonal, and an innovative 1920 × 1200 WUXGA, 1″diagonal, CMOS‐based microdisplays can be curved at R = 45 mm radius of curvature (1D) with no negative impact onto the circuit electrical characteristics. This feature can allow significant innovation on the system and application because it can help to redesign simpler and lighter optical engine systems, in the same manner as for curved image sensors. These results can be obtained owing to the integration of a new protective hard coat layer that has been used in conjunction with a robust thin‐film encapsulation to protect OLEDs from mechanical ingress (from process steps and handling) and oxidizing gas of the atmosphere, respectively. Results have been produced within the framework of the EU‐funded, H2020 project, called L arge cost‐effective O LED MI cro D isplays (LOMID and their applications).     

SKEL: A fundamental property desirable in ATM switches for simple traffic management - illustrations with generic output-buffered and input-buffered switches

To simplify traffic control in a network, it is desirable that the traffic-control policy at a network node depends only on the external traffic loads on the input and output links, but not on the detail addressing or distribution of packets from inputs to outputs. In other words, it should be possible to guarantee the grade-of-service of an input-output connection by controlling the aggregate loads on the input and output. Switch nodes in which such a traffic-control policy is possible are said to have the property of the sufficiency of the knowledge of external loads (SKEL). One way to demonstrate the feasibility of SKEL for a particular switch is to show that the performance under any nonuniform traffic distribution from inputs to outputs is better than or close to the performance under the uniform traffic distribution. The contributions of this paper are twofold: clarifying issues related to SKEL and establishing its feasibility for generic input- and output-buffered switches on a rigorous basis. The following summarizes our major results: (1) The packet-loss probability due to the Knockout switch-design principle for packets destined for an arbitrary output is maximum when the traffic to that output originates uniformly from all inputs; (2) The packet-loss probability for packets destined for a particular output under uniform traffic closely approximates the loss probability for packets from the worst-case input to that output under nonuniform traffic; (3) For mean and variance of delay, similar results as in (1) and (2) can be obtained; (4) For an input-queued switch, external link loadings that do not give rise to queue saturation under uniform traffic will not do so under nonuniform traffic either.     

Computing spanning line segments in three dimensions

A set of spanning line segments in a polyhedronP preserves the property of intersection; that is, a plane intersectsP if and only if it also intersects . This paper gives a linear time algorithm for constructing for a polyhedron withN extreme vertices. IfN is odd, the algorithm is optimal in yielding [N/2] + 1 spanning line segments. IfN is even, it gives (N/2) + 1, which is optimal in some cases and nearly optimal in others.     

A fast microfluidic mixer based on acoustically driven sidewall-trapped microbubbles

Due to the low Reynolds number associated with microscale fluid flow, it is difficult to rapidly and homogenously mix two fluids. In this letter, we report a fast and homogenized mixing device through the use of a bubble-based microfluidic structure. This micromixing device worked by trapping air bubbles within the pre-designed grooves on the sidewalls of the channel. When acoustically driven, the membranes (liquid/air interfaces) of these trapped bubbles started to oscillate. The bubble oscillation resulted in a microstreaming phenomenon—strong pressure and velocity fluctuations in the bulk liquid, thus giving rise to fast and homogenized mixing of two side-by-side flowing fluids. The performance of the mixer was characterized by mixing deionized water and ink at different flow rates. The mixing time was measured to be as small as 120 ms.     

Involvement of cAMP-dependent protein kinase in the nucleus accumbens in cocaine self-administration and relapse of cocaine-seeking behavior

cAMP-dependent protein kinase (PKA) in the nucleus accumbens (NAc) has been implicated in cocaine addiction because (1) cocaine reinforcement is mediated by dopamine receptors that modulate cAMP formation, and (2) repeated exposure to cocaine upregulates the cAMP system in NAc neurons. This study tested PKA involvement in cocaine self-administration and relapse of cocaine-seeking behavior by infusing cAMP analogs that activate or inhibit PKA into the NAc of rats. Bilateral intra-NAc infusions of the PKA inhibitor Rp-cAMPS reduced baseline cocaine self-administration, shifted the dose-response curve for cocaine self-administration to the left, and induced relapse of cocaine-seeking behavior after extinction from cocaine self-administration, consistent with an enhancement of cocaine effects in each paradigm. In contrast, pretreatment with intra-NAc infusions of a PKA activator, Sp-cAMPS or dibutyryl cAMP, increased baseline cocaine self-administration during the second hour of testing and shifted the dose-response curve to the right, consistent with an antagonist-like action. After extinction from cocaine self-administration, similar infusions of Sp-cAMPS induced generalized responding at both drug-paired and inactive levers. As an index of PKA activity in vivo, NAc infusions of Rp-cAMPS reduced basal levels of dopamine-regulated phosphoprotein-32 phosphorylation and blocked amphetamine-induced increases in cAMP response element-binding protein (CREB) phosphorylation. Conversely, NAc infusions of Sp-cAMPS increased phosphorylation of CREB. Together, these results suggest that sustained upregulation of the cAMP system in the NAc after repeated cocaine exposure could underlie tolerance to cocaine reinforcement, whereas acute inhibition of this system may contribute to drug craving and relapse in addicted subjects.     

A phase II study of BTI-322, a monoclonal anti-CD2 antibody, for treatment of steroid-resistant acute graft-versus-host disease

BTI-322, a rat monoclonal IgG2b directed against the CD2 antigen on T cells and natural killer (NK) cells, blocks primary and memory alloantigen proliferative responses in vitro. We have evaluated the pharmacokinetics and safety of BTI-322 during treatment of 20 transplant recipients with steroid-refractory acute graft-versus-host disease (GVHD). Treatment consisted of BTI-322 by intravenous (IV) bolus or 30-minute infusion at approximately 0.1 mg/kg/d for 10 days in addition to continuing high-dose steroids and tacrolimus or cyclosporine. Pharmacokinetic sampling was performed in 10 patients; the t1/2 +/- SE was 9.1 +/- 1.3 hours, the Cmax was 2,549 +/- 291 ng/mL, the Vd was 3.97 +/- 0.95 L, and the Vd/kg was 0. 05 +/- 0.01 L/kg. Ten patients experienced transient dyspnea sometimes accompanied by nausea, vomiting, diarrhea, and tachycardia shortly after the initial bolus dose of drug, but serious drug-related adverse events were not seen during the remainder of the infusions. At the end of treatment (day 11), there were six patients with complete responses and five with a reduction in grade of GVHD for a total response rate of 55% (95% confidence interval [CI], 32% to 77%). Antibodies targeting CD2 may be active in the treatment of acute GVHD, and evaluation of a humanized form of BTI-322 is warranted.     

Effects of time of testing, stress level, and number of conditioning days on naloxone sensitivity of conditioned stress-induced analgesia in rats.

In 2 experiments, an anticipatory conditioned stimulus/stimuli (CS) and a shock-associated CS were used. Duration of exposure to the anticipatory CS was long, as in studies reporting opioid conditioned stress-induced analgesia (CSIA), whereas duration of shock-associated CS was short, as in nonopioid CSIA. Effects of unconditioned stimulus/stimuli (UCS) strength were investigated by using 3 levels of footshock, and the development of CSIA was monitored by using different levels of training (1–6 days). CSIA, measured in both anticipatory and postexposure test periods, was found to be relatively stable across tail-flick trials within days and insensitive to strength of shock. As training progressed, CSIA increased with repeated CS–UCS pairings. We tested for opioid involvement using naloxone and found opioid and nonopioid mechanisms underlying CSIA; these mechanisms combined to form a stable level of analgesia. Data suggest that stress level and amount of training interact to activate opioid and nonopioid mechanisms of CSIA. Discrepancies in previous studies regarding naloxone sensitivity may be attributable to differences in stress levels, test periods, and durations of exposure to shock-related cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)