6,339 research outputs found
Efficient Estimation of Heat Kernel PageRank for Local Clustering
Given an undirected graph G and a seed node s, the local clustering problem
aims to identify a high-quality cluster containing s in time roughly
proportional to the size of the cluster, regardless of the size of G. This
problem finds numerous applications on large-scale graphs. Recently, heat
kernel PageRank (HKPR), which is a measure of the proximity of nodes in graphs,
is applied to this problem and found to be more efficient compared with prior
methods. However, existing solutions for computing HKPR either are
prohibitively expensive or provide unsatisfactory error approximation on HKPR
values, rendering them impractical especially on billion-edge graphs.
In this paper, we present TEA and TEA+, two novel local graph clustering
algorithms based on HKPR, to address the aforementioned limitations.
Specifically, these algorithms provide non-trivial theoretical guarantees in
relative error of HKPR values and the time complexity. The basic idea is to
utilize deterministic graph traversal to produce a rough estimation of exact
HKPR vector, and then exploit Monte-Carlo random walks to refine the results in
an optimized and non-trivial way. In particular, TEA+ offers practical
efficiency and effectiveness due to non-trivial optimizations. Extensive
experiments on real-world datasets demonstrate that TEA+ outperforms the
state-of-the-art algorithm by more than four times on most benchmark datasets
in terms of computational time when achieving the same clustering quality, and
in particular, is an order of magnitude faster on large graphs including the
widely studied Twitter and Friendster datasets.Comment: The technical report for the full research paper accepted in the
SIGMOD 201
A common founding clone with TP53 and PTEN mutations gives rise to a concurrent germ cell tumor and acute megakaryoblastic leukemia
We report the findings from a patient who presented with a concurrent mediastinal germ cell tumor (GCT) and acute myeloid leukemia (AML). Bone marrow pathology was consistent with a diagnosis of acute megakaryoblastic leukemia (AML M7), and biopsy of an anterior mediastinal mass was consistent with a nonseminomatous GCT. Prior studies have described associations between hematological malignancies, including AML M7 and nonseminomatous GCTs, and it was recently suggested that a common founding clone initiated both cancers. We performed enhanced exome sequencing on the GCT and the AML M7 from our patient to define the clonal relationship between the two cancers. We found that both samples contained somatic mutations in PTEN (C136R missense) and TP53 (R213 frameshift). The mutations in PTEN and TP53 were present at âź100% variant allele frequency (VAF) in both tumors. In addition, we detected and validated five other shared somatic mutations. The copy-number analysis of the AML exome data revealed an amplification of Chromosome 12p. We also identified a heterozygous germline variant in FANCA (S858R), which is known to be associated with Fanconi anemia but is of uncertain significance here. In summary, our data not only support a common founding clone for these cancers but also suggest that a specific set of distinct genomic alterations (in PTEN and TP53) underlies the rare association between GCT and AML. This association is likely linked to the treatment resistance and extremely poor outcome of these patients. We cannot resolve the clonal evolution of these tumors given limitations of our data
Hydrodynamical Simulations of the Lyman Alpha Forest: Model Comparisons
We investigate the properties of the Lyman alpha forest as predicted by
numerical simulations for a range of currently viable cosmological models. This
is done in order to understand the dependencies of the forest on cosmological
parameters. Focusing on the redshift range from two to four, we show that: (1)
most of the evolution in the distributions of optical depth, flux and column
density can be understood by simple scaling relations, (2) the shape of optical
depth distribution is a sensitive probe of the amplitude of density
fluctuations on scales of a few hundred kpc, (3) the mean of the b distribution
(a measure of the width of the absorption lines) is also very sensitive to
fluctuations on these scales, and decreases as they increase. We perform a
preliminary comparison to observations, where available. A number of other
properties are also examined, including the evolution in the number of lines,
the two-point flux distribution and the HeII opacity.Comment: 37 pages, 21 figures, submitted to Ap
Natural Experiment Examining Impact of Aggressive Screening and Treatment on Prostate Cancer Mortality in Two Fixed Cohorts from Seattle Area and Connecticut
To determine whether the more intensive screening and treatment for prostate cancer in the Seattleâ Puget Sound area in 1987â 90 led to lower mortality from prostate cancer than in Connecticut
Graphite Nanoeraser
We present here a method for cleaning intermediate-size (5~50nm)
contamination from highly oriented pyrolytic graphite. Electron beam deposition
causes a continuous increase of carbonaceous material on graphene and graphite
surfaces, which is difficult to remove by conventional techniques. Direct
mechanical wiping using a graphite nanoeraser is observed to drastically reduce
the amount of contamination. After the mechanical removal of contamination, the
graphite surfaces were able to self-retract after shearing, indicating that van
der Waals contact bonding is restored. Since contact bonding provides an
indication of a level of cleanliness normally only attainable in a high-quality
clean-room, we discuss potential applications in preparation of ultraclean
surfaces.Comment: 10 pages, two figure
SnTox3 Acts in Effector Triggered Susceptibility to Induce Disease on Wheat Carrying the Snn3 Gene
The necrotrophic fungus Stagonospora nodorum produces multiple proteinaceous host-selective toxins (HSTs) which act in effector triggered susceptibility. Here, we report the molecular cloning and functional characterization of the SnTox3-encoding gene, designated SnTox3, as well as the initial characterization of the SnTox3 protein. SnTox3 is a 693 bp intron-free gene with little obvious homology to other known genes. The predicted immature SnTox3 protein is 25.8 kDa in size. A 20 amino acid signal sequence as well as a possible pro sequence are predicted. Six cysteine residues are predicted to form disulfide bonds and are shown to be important for SnTox3 activity. Using heterologous expression in Pichia pastoris and transformation into an avirulent S. nodorum isolate, we show that SnTox3 encodes the SnTox3 protein and that SnTox3 interacts with the wheat susceptibility gene Snn3. In addition, the avirulent S. nodorum isolate transformed with SnTox3 was virulent on host lines expressing the Snn3 gene. SnTox3-disrupted mutants were deficient in the production of SnTox3 and avirulent on the Snn3 differential wheat line BG220. An analysis of genetic diversity revealed that SnTox3 is present in 60.1% of a worldwide collection of 923 isolates and occurs as eleven nucleotide haplotypes resulting in four amino acid haplotypes. The cloning of SnTox3 provides a fundamental tool for the investigation of the S. nodorum-wheat interaction, as well as vital information for the general characterization of necrotroph-plant interactions.This work was supported by USDA-ARS CRIS projects 5442-22000-043-00D and 5442-22000-030-00D
An oligofluorene truxene based distributed feedback laser for biosensing applications
The first example of an all-organic oligofluorene truxene based distributed feedback laser for the detection of a specific proteinâsmall molecule interaction is reported. The protein avidin was detected down to View the MathML source1ÎźgmLâ1 using our biotin-labelled biosensor platform. This interaction was both selective and reversible when biotin was replaced with desthiobiotin. Avidin detection was not perturbed by Bovine Serum Albumin up to View the MathML source50,000ÎźgmLâ1. Our biosensor offers a new detection platform that is both highly sensitive, modular and potentially re-usable
Effects of carpal tunnel syndrome on force coordination and muscle coherence during precision pinch
Carpal tunnel syndrome (CTS), caused by entrapment of the median nerve in the carpal tunnel, impairs hand function including dexterous manipulation. The purpose of this study was to investigate the effects of CTS on force coordination and muscle coherence during low-intensity sustained precision pinch while the wrist assumed different postures. Twenty subjects (10 CTS patients and 10 asymptomatic controls) participated in this study. An instrumented pinch device was used to measure the thumb and index finger forces while simultaneously collecting surface electromyographic activities of the abductor pollicis brevis (APB) and first dorsal interosseous (FDI) muscles. Subjects performed a sustained precision pinch at 10% maximum pinch force for 15 sec with the wrist stabilized at 30° extension, neutral, or 30° flexion using customized splints. The force discrepancy and the force coordination angle between the thumb and index finger forces were calculated, as well as the β-band (15-30 Hz) coherence between APB and FDI. The index finger applied greater force than the thumb (p 0.05). The directional force coordination was not significantly affected by wrist posture or CTS (p > 0.05). In general, digit force coordination during precision pinch seems to be sensitive to wrist flexion, but is not affected by CTS. The β-band muscular coherence was increased by wrist flexion for CTS patients (p < 0.05), which could be a compensatory mechanism for the flexion-induced exacerbation of CTS symptoms. This study demonstrates that wrist flexion negatively influences muscle and force coordination in CTS patients supporting the avoidance of flexion posture for symptom exacerbation and functional performance
Change in Depression, Confidence, and Physical Function Among Older Adults With Mild Cognitive Impairment
Background and Purpose
Nearly a quarter of those in the US over age 71 experience mild cognitive impairment (MCI). Persons with MCI (PwMCI) battle depression and progressive disengagement from daily activities, which contribute to participation restriction and activity limitation. Daily engagement in meaningful activity (DEMA) is a tailored intervention designed to benefit PwMCI and their caregivers through preserved engagement and supported adjustment to cognitive changes. This secondary analysis was guided by the International Classification of Functioning, Disability and Health (ICF) model. Aims were to (i) explore the extent to which change in self-rated activity performance and physical function can predict change in depressive symptoms, (ii) evaluate for difference in confidence and depressive symptoms at ICF levels of activity and participation, and (iii) quantify the impact of daily engagement at the ICF level of participation on physical function.
Methods
A secondary analysis was conducted using data from the parent study, which was a two-group randomized trial involving PwMCI and their informal caregivers participating in the Indiana Alzheimer Disease Center DEMA program. Quantitative analysis (dyads: DEMA N = 20, Information Support N = 20) examined outcomes at posttest and follow-up. Analysis employed linear regression to model the relationship between explanatory and dependent variables and independent t-test to examine for difference in confidence, depression, and physical function.
Results and Discussion
At posttest, change in self-rated performance predicted change in depressive symptoms. Those in the DEMA group who engaged in activity at the ICF level of participation demonstrated a significant increase in confidence and physical function. Although not significant, the control group posttest results showed a mean decrease in confidence.
Conclusions
Results demonstrate a positive impact of DEMA on depressive symptoms, confidence, and physical function. Change in occupational performance predicted change in depressive symptoms. Confidence significantly improved among those who engaged at the ICF participation level. A larger, randomized controlled longitudinal trial is needed to better assess the impact of DEMA on physical function, activity, participation restriction and quality of life
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