Smoothing a Rock by Chipping

We investigate an idealized model for the size reduction and smoothing of a polygonal rock due to repeated chipping at corners. Each chip is sufficiently small so that only a single corner and a fraction of its two adjacent sides are cut from the object in a single chipping event. After many chips have been cut away, the resulting shape of the rock is generally anisotropic, with facet lengths and corner angles distributed over a broad range. Although a well-defined shape is quickly reached for each realization, there are large fluctuations between realizations.Comment: 7 pages, 10 figures, 2-column revtex4 format; version 2: final published form in PRE; contains minor changes in response to referee comment

The Semi Implicit Gradient Augmented Level Set Method

Here a semi-implicit formulation of the gradient augmented level set method is presented. By tracking both the level set and it's gradient accurate subgrid information is provided,leading to highly accurate descriptions of a moving interface. The result is a hybrid Lagrangian-Eulerian method that may be easily applied in two or three dimensions. The new approach allows for the investigation of interfaces evolving by mean curvature and by the intrinsic Laplacian of the curvature. In this work the algorithm, convergence and accuracy results are presented. Several numerical experiments in both two and three dimensions demonstrate the stability of the scheme.Comment: 19 Pages, 14 Figure

Journal Staff

This book constitutes the refereed proceedings of the 18th Scandinavian Conference on Image Analysis, SCIA 2013, held in Espoo, Finland, in June 2013. The 67 revised full papers presented were carefully reviewed and selected from 132 submissions. The papers are organized in topical sections on feature extraction and segmentation, pattern recognition and machine learning, medical and biomedical image analysis, faces and gestures, object and scene recognition, matching, registration, and alignment, 3D vision, color and multispectral image analysis, motion analysis, systems and applications, human-centered computing, and video and multimedia analysis

Pattern Formation of Glioma Cells: Effects of Adhesion

We investigate clustering of malignant glioma cells. \emph{In vitro} experiments in collagen gels identified a cell line that formed clusters in a region of low cell density, whereas a very similar cell line (which lacks an important mutation) did not cluster significantly. We hypothesize that the mutation affects the strength of cell-cell adhesion. We investigate this effect in a new experiment, which follows the clustering dynamics of glioma cells on a surface. We interpret our results in terms of a stochastic model and identify two mechanisms of clustering. First, there is a critical value of the strength of adhesion; above the threshold, large clusters grow from a homogeneous suspension of cells; below it, the system remains homogeneous, similarly to the ordinary phase separation. Second, when cells form a cluster, we have evidence that they increase their proliferation rate. We have successfully reproduced the experimental findings and found that both mechanisms are crucial for cluster formation and growth.Comment: 6 pages, 6 figure

Numerical Simulation of Grain Boundary Grooving By Level Set Method

A numerical investigation of grain-boundary grooving by means of a Level Set method is carried out. An idealized polygranular interconnect which consists of grains separated by parallel grain boundaries aligned normal to the average orientation of the surface is considered. The surface diffusion is the only physical mechanism assumed. The surface diffusion is driven by surface curvature gradients, and a fixed surface slope and zero atomic flux are assumed at the groove root. The corresponding mathematical system is an initial boundary value problem for a two-dimensional Hamilton-Jacobi type equation. The results obtained are in good agreement with both Mullins' analytical "small slope" solution of the linearized problem (W.W. Mullins, 1957) (for the case of an isolated grain boundary) and with solution for the periodic array of grain boundaries (S.A. Hackney, 1988).Comment: Submitted to the Journal of Computational Physics (19 pages, 8 Postscript figures, 3 tables, 29 references

A Prospective Safety Trial of Atorvastatin Treatment to Assess Rebleeding after Spontaneous Intracerebral Hemorrhage: A Serial MRI Investigation

AIM: This study was designed to determine any rebleeding after atorvastatin treatment following spontaneous intracerebral hemorrhage (ICH) in a prospective safety trial. PATIENTS: Atorvastatin (80 mg/day) therapy was initiated in 6 patients with primary ICH with admission Glasgow Coma Score (GCS) \u3e5 within 24 hours of ictus and continued for 7 days, with the dose tapered and treatment terminated over the next 5 days. Patients were studied longitudinally by multiparametric magnetic resonance imaging (MRI) at three time points: acute (3 to 5 days), subacute (4 to 6 weeks) and chronic (3 to 4 months). Imaging sequences included T1, T2-weighted imaging (T2WI), diffusion tensor imaging (DTI) and contrast-enhanced MRI measures of cerebral perfusion, blood volume and blood-brain barrier (BBB) permeability. Susceptibility weighted imaging (SWI) was used to identify primary ICH and to check for secondary rebleeding. Final outcome was assessed using Glasgow Outcome Score (GOS) at 3-4 months. RESULTS: Mean admission GCS was 13.2±4.0 and mean GOS at 3 months was 4.5±0.6. Hemorrhagic lesions were segmented into core and rim areas. Mean lesion volumes decreased significantly between the acute and chronic study time points (p=0.008). Average ipsilateral hemispheric tissue loss at 3 to 4 months was 11.4±4.6 cm3. MRI showed acutely reduced CBF (p=0.004) and CBV (p=0.002) in the rim, followed by steady normalization. Apparent diffusion coefficient of water (ADC) in the rim demonstrated no alterations at any of the time points (p\u3e0.2). The T2 values were significantly elevated in the rim acutely (p=0.02), but later returned to baseline. The ICH core showed sustained low CBF and CBV values concurrent with a small reduction in ADC acutely, but significant ADC elevation at the end suggestive of irreversible injury. CONCLUSION: Despite the presence of a small, probably permanent, cerebral lesion in the ICH core, no patients exhibited post-treatment rebleeding. These data suggest that larger, Phase 2 trials are warranted to establish long term clinical safety of atorvastatin in spontaneous ICH

Waste Clearance in the Brain

Waste clearance (WC) is an essential process for brain homeostasis, which is required for the proper and healthy functioning of all cerebrovascular and parenchymal brain cells. This review features our current understanding of brain WC, both within and external to the brain parenchyma. We describe the interplay of the blood-brain barrier (BBB), interstitial fluid (ISF), and perivascular spaces within the brain parenchyma for brain WC directly into the blood and/or cerebrospinal fluid (CSF). We also discuss the relevant role of the CSF and its exit routes in mediating WC. Recent discoveries of the glymphatic system and meningeal lymphatic vessels, and their relevance to brain WC are highlighted. Controversies related to brain WC research and potential future directions are presented

MicroRNA-214 enriched exosomes from human cerebral endothelial cells (hCEC) sensitize hepatocellular carcinoma to anti-cancer drugs

Hepatocellular carcinoma (HCC) is the most common primary liver tumor worldwide. Current medical therapy for HCC has limited efficacy. The present study tests the hypothesis that human cerebral endothelial cell-derived exosomes carrying elevated miR-214 (hCEC-Exo-214) can amplify the efficacy of anti-cancer drugs on HCC cells. Treatment of HepG2 and Hep3B cells with hCEC-Exo-214 in combination with anti-cancer agents, oxaliplatin or sorafenib, significantly reduced cancer cell viability and invasion compared with monotherapy with either drug. Additionally, the therapeutic effect of the combination therapy was detected in primary tumor cells derived from patients with HCC. The ability of hCEC-Exo-214 in sensitizing HCC cells to anti-cancer drugs was specific, in that combination therapy did not affect the viability and invasion of human liver epithelial cells and non-cancer primary cells. Furthermore, compared to monotherapy with oxaliplatin and sorafenib, hCEC-Exo-214 in combination with either drug substantially reduced protein levels of P-glycoprotein (P-gp) and splicing factor 3B subunit 3 (SF3B3) in HCC cells. P-gp and SF3B3 are among miR-214 target genes and are known to mediate drug resistance and cancer cell proliferation, respectively. In conclusion, the present in vitro study provides evidence that hCEC-Exo-214 significantly enhances the anti-tumor efficacy of oxaliplatin and sorafenib on HCC cells

Proteomic Profiles of Exosomes of Septic Patients Presenting to the Emergency Department Compared to Healthy Controls

BACKGROUND: Septic Emergency Department (ED) patients provide a unique opportunity to investigate early sepsis. Recent work focuses on exosomes, nanoparticle-sized lipid vesicles (30-130 nm) that are released into the bloodstream to transfer its contents (RNA, miRNA, DNA, protein) to other cells. Little is known about how early changes related to exosomes may contribute to the dysregulated inflammatory septic response that leads to multi-organ dysfunction. We aimed to evaluate proteomic profiles of plasma derived exosomes obtained from septic ED patients and healthy controls. METHODS: This is a prospective observational pilot study evaluating a plasma proteomic exosome profile at an urban tertiary care hospital ED using a single venipuncture blood draw, collecting 40 cc Ethylenediaminetetraacetic acid (EDTA) blood. MEASUREMENTS: We recruited seven patients in the ED within 6 h of their presentation and five healthy controls. Plasma exosomes were isolated using the Invitrogen Total Exosome Isolation Kit. Exosome proteomic profiles were analyzed using fusion mass spectroscopy and Proteome Discoverer. Principal component analysis (PCA) and differential expression analysis (DEA) for sepsis versus control was performed. RESULTS: PCA of 261 proteins demonstrated septic patients and healthy controls were distributed in two groups. DEA revealed that 62 (23.8%) proteins differed between the exosomes of septic patients and healthy controls, CONCLUSION: Exosome proteomic profiles of septic ED patients differ from their healthy counterparts with regard to acute phase response and inflammation

Level Set Approach to Reversible Epitaxial Growth

We generalize the level set approach to model epitaxial growth to include thermal detachment of atoms from island edges. This means that islands do not always grow and island dissociation can occur. We make no assumptions about a critical nucleus. Excellent quantitative agreement is obtained with kinetic Monte Carlo simulations for island densities and island size distributions in the submonolayer regime.Comment: 7 pages, 9 figure