Adaptive Partitioning for Large-Scale Dynamic Graphs

Abstract—In the last years, large-scale graph processing has gained increasing attention, with most recent systems placing particular emphasis on latency. One possible technique to improve runtime performance in a distributed graph processing system is to reduce network communication. The most notable way to achieve this goal is to partition the graph by minimizing the num-ber of edges that connect vertices assigned to different machines, while keeping the load balanced. However, real-world graphs are highly dynamic, with vertices and edges being constantly added and removed. Carefully updating the partitioning of the graph to reflect these changes is necessary to avoid the introduction of an extensive number of cut edges, which would gradually worsen computation performance. In this paper we show that performance degradation in dynamic graph processing systems can be avoided by adapting continuously the graph partitions as the graph changes. We present a novel highly scalable adaptive partitioning strategy, and show a number of refinements that make it work under the constraints of a large-scale distributed system. The partitioning strategy is based on iterative vertex migrations, relying only on local information. We have implemented the technique in a graph processing system, and we show through three real-world scenarios how adapting graph partitioning reduces execution time by over 50 % when compared to commonly used hash-partitioning. I

Development of Protective Clothing against Nanoparticle Based on Electrospun Nanofibers

In this paper, the development of efficient protective clothing against nanoparticulate aerosols is presented. Nanofibrous mats of polyamide 6 (PA6) were deposited onto a nonwoven viscose substrate by electrospinning technique. The influence of electrospinning parameters, including solution concentration, viscosity, and conductivity, was studied for the production of nonwovens with controlled fiber diameter showing a size distribution ranging from 66 to 195 nm. By varying several process parameters, textiles with different thickness of the nanofiber layer and thus air permeability were obtained. A hot-press lamination process using a thermoplastic resin as glue was applied to improve the adhesion of the nanofiber layer onto the textile support. After 1500 cycles of repeated compression and torsion, the nanofiber layer was still firmly attached to the support, while mechanical damage is visible in some areas. The penetration of NaCl particles with diameter ranging from 15 to 300 nm through the electrospun textiles was found to be strongly dependent on nanofiber layer thickness. A really thin nanofiber coating provides up to 80% retention of 20 nm size particles and over 50% retention of 200 nm size nanoparticles. Increasing the thickness of the nanofiber mat, the filtration efficiency was increased to over 99% along the whole nanoparticle range. The results obtained highlight the potential of nanofibers in the development of efficient personal protective equipments against nanoparticles.The financial support of this work was provided by MICINN (Spanish Ministry of Science and Innovation) and ERDF (European Regional Development Fund) (ref.: PSE-420000-2008–003), and ACC1´O (Catalan Business Competitiveness Support Agency

Wavelet-based methodology for [15O]-H20 PET brain activation assessment

[Abstract] AMI International Conference 2003, September 21-27, Madrid, Spain: "High Resolution Molecular Imaging: from Basic Science to Clinical Applications"Statistical parametric mapping (SPM) is a voxel-byvoxel analysis method commonly used for the detection of brain activation patterns. An alternative approach is the use of multiscale information by means of wavelet analysis. In this study, we have compared the detection of brain activations using conventional SPM and a statistical wavelet analysis in a set of realistic simulated [15O]-H20 positron emission tomography (PET) phantomsPublicad

Cirugía de la columna lumbar degenerativa

En una realidad la gran demanda actual de fusiones de la columna lumbar. Los resultados clínicos obtenidos con la fusión posterolateral se ven claramente superados con las fusiones anteroposteriores. Se realiza una revisión bibliográfica de las diferentes formas de fusión de la columna lumbar y la reaparición del concepto de soporte de columna anterior. Se establecen las indicaciones y las ventajas de la fusión anteroposterior lumbar, describiéndose las posibles vías de abordaje posterior y anteriores abiertas y mínimamente invasivas. Se clasifican los modernos implantes utilizados para soporte de la columna anterior. Se detallan ventajas e inconvenientes de las vías anterior y posterior.It is a reality the increasing number of the lumbar fusions. Clinical results show that the anteroposterior lumbar fusions achieve greater success rates than the posterolateral ones. A paper review of the different ways of lumbar fusion is carried out whit the update of the anterior column support concept. Indications and advantages: posterior, anterior and minimal invasive ones. The last spine cages used for anterior column support art classified. Advantages and drawbacks of the both approaches anterior and posterior are studied

Automatic scoring of sister chromatid exchanges by image analysis in a dose response experiment

A system which automatically selects second division metaphases and then, automatically scores the number of seEs of each cell is described. In on initial set of experiments, the performance of the components of the system was measured using a doto set in which metophases had been visually classified as either 2nd division or other; and in 2nd division metaphoses, every SeE had been marked on a hard copy. seE scoring had a true positive rate of about 75% and a false positive rate of about 1.5 false SeEs per metaphase analyzed. Second division detection hod a true positive rate of 80% and a false positive rate of about 10% of the non-2nd division cells. Next, the overall system was compared to human visual scoring in a dose-response experiment by analyzing the effect of mitomycin C on human chromosomes scored visually by two observers and by the fully automatic scoring. Human visual scoring and machine analysis showed similar dose responses, but the variability between them was considerable.This study was supported by the European Community's Concerted Action on Automated Cytogenetics (EC Medical and Health Research Program, project no. 11.1.11 13).Publicad

Attentional bias towards threatening and neutral facial expressions in high trait anxious children.

Research suggests anxious children display increased attentional biases for threat-related stimuli. However, findings based upon spatial domain research are equivocal. Moreover, few studies allow for the independent analysis of trials containing neutral (i.e., potentially ambiguous) faces. Here, we report two temporal attentional blink experiments with high trait anxious (HTA) and low trait anxious (LTA) children. In an emotive experiment, we manipulated the valence of the second target (T2: threatening/positive/neutral). Results revealed that HTA, relative to LTA, children demonstrated better performance on neutral trials. Additionally, HTA children demonstrated a threat-superiority effect whereas LTA children demonstrated an emotion-superiority effect. In a non-emotive control, no differences between HTA and LTA children were observed. Results suggest trait anxiety is associated with an attentional bias for threat in children. Additionally, the neutral face finding suggests HTA children bias attention towards ambiguity. These findings could have important implications for current anxiety disorder research and treatments

Accuracy of CT-based attenuation correction in bone imaging with PET/CT

Proceeding of: 2007 IEEE Nuclear Science Symposium Conference Record (NSS'07), Honolulu, Hawaii, USA, Oct. 27 - Nov. 3, 2007PET/CT has become the most comprehensive diagnostic tool in oncology imaging providing improved lesion identification and localization. Bone is a common site of metastasis and the quantitative accuracy of PET images in bone tissue is important for assessing response to therapy. The use of CT images for attenuation correction is becoming a standard procedure in these scanners. However the impact of CT-based attenuation correction (CTAC) on the accuracy of PET tracer uptake values measured in bone has not been carefully evaluated, having only been carefully studied in soft tissue. We investigated the accuracy of CTAC on PET bone images by comparing the attenuation coefficients with PET transmission scans. For this, we imaged frozen bovine femur segments in a 20x20 cm cylindrical phantom. Different regions of the bones in both images were segmented by using thresholding and erosion methods to get equivalent volume masks. Differences in linear attenuation coefficients between the two images were then calculated. We repeated this analysis using patient images from the same patient imaged on the GE Advance PET scanner and the GE Discovery STE PET/CT scanner. The impact of the errors in the linear attenuation coefficients on PET SUV measurements was evaluated by simulations using the patent images with known bone disease and elevated levels of FDG uptake in bone (e.g. SUV = 5) at disease sites. The impact of the errors in the linear attenuation coefficients was then estimated by forward projection and reconstruction, after including the effects of attenuation and attenuation correction.This work was supported in kart by Agencia Antidroga de la Comunidad de Madrid (S-SAL2007), Ministerio de Sanidad y Consumo (CIBER CB06/01/0079), and Ministerio de Industria (Programa CENIT). It was also supported in part by NIH grants R01- CA124573 and R01-CA115870