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We propose a new static high-performance mesh data structure for triangle surface meshes on the GPU. Our data structure is carefully designed for parallel execution while capturing mesh locality and confining data access, as much as possible, within the GPU's fast "shared memory." We achieve this by subdividing the mesh into patches and representing these patches compactly using a matrix-based representation. Our patching technique is decorated with ribbons , thin mesh strips around patches that eliminate the need to communicate between different computation thread blocks, resulting in consistent high throughput. We call our data structure RXMesh : Ribbon-matriX Mesh. We hide the complexity of our data structure behind a flexible but powerful programming model that helps deliver high performance by inducing load balance even in highly irregular input meshes. We show the efficacy of our programming model on common geometry processing applications---mesh smoothing and filtering, geodesic distance, and vertex normal computation. For evaluation, we benchmark our data structure against well-optimized GPU and (single and multi-core) CPU data structures and show significant speedups.

We present Neon, a new programming model for grid-based computation with an intuitive, easy-to-use interface that allows domain experts to take full advantage of single-node multi-GPU systems. Neon decouples data structure from computation and back end configurations, allowing the same user code to operate on a variety of data structures and devices. Neon relies on a set of hierarchical abstractions that allow the user to write their applications as if they were sequential applications, while the runtime handles distribution across multiple GPUs and performs optimizations such as overlapping computation and communication without user intervention. We evaluate our programming model on several applications: a Lattice Boltzmann fluid solver, a finite-difference Poisson solver and a finite-element linear elastic solver. We show that these applications can be implemented concisely and scale well with the number of GPUs—achieving more than 99% of ideal efficiency.

Surgical ablation procedure is commonly performed in patients with atrial fibrillation (AF) undergoing cardiac surgeries; however, the evidence regarding its impact on in-hospital cardiovascular outcomes is controversial.We queried the Nationwide Inpatient Sample Database for patients with AF who underwent cardiac surgeries from 1998 to 2013. We performed a propensity-score matching including 21 various baseline characteristics to compare those who underwent surgical ablation with those who had not.A total of 47,964 hospitalizations were included in our final analysis. On propensity matching, 23,975 were in the surgical ablation group and 23,990 in the control group. The primary outcome of in-hospital mortality was lower in the surgical ablation group compared with the control group (3.6% versus 4.2%, p 0.001). The surgical ablation group was associated with lower in-hospital cerebrovascular accident (2.0% versus 2.8%, p0.001), cardiogenic shock (2.6% versus 3.6%, p0.001), use of intraaortic balloon pump (5.1% versus 5.8%, p = 0.001), and shorter length of hospital stay (12.3 ± 10.1 versus 12.5 ± 10.3 days, p = 0.008). There was no difference between the surgical ablation and control groups in the incidence of cardiac tamponade (0.4% versus 0.3%, p = 0.296). The surgical ablation group was associated with a higher rate of complete heart block (5.2% versus 4.3%, p0.001) and permanent pacemaker insertion (8.6% versus 8.0%, p = 0.01).In this large analysis of almost 50,000 patients with AF undergoing cardiac surgery, surgical ablation appears to be safe in the short term. Future studies should focus on evaluating the long-term effectiveness of this procedure.

Organoaxial gastric volvulus occurs when the stomach rotates on its longitudinal axis connecting the gastroesophageal junction to the pylorus. With that, the antrum of the stomach usually rotates in the opposite direction in rela-tion to its fundus (1). This phenomenon has often been known to be associated with diaphragmatic defects (2) Importantly, abnormal rotation of the stomach of more than 180° is a life threatening emergency that may create a closed loop ob- struction which may result in incarceration leading to strangulation, and hence, a surgical emergency. We present the case of a middle-aged female who presented with organoaxial gastric volvulus and had an associated Type IV paraesophageal hiatal hernia that was treated electively. Normally an emergent gastric volvulus is diagnosed via Borchardt’s classic triad (epigastric pain, unproductive vomiting and diffculty inserting a nasogastric tube); however in this patient the nasogastric tube (NGT) was passed into the antrum which allowed additional time for resusci-tation with fuids and other symptomatic relief.

The association of myasthenia gravis (MG) with thymoma is about 15%, which increases to about 35% in older patients (1,19). Thymomas represent nearly 50% of tumors in the anterior mediastinum and if large enough may cause mediastinal widening (12). The connection between the thymus gland and MG has led to the medical recommendation of a thymectomy, however, a thymectomy does not cure MG but may significantly decrease the symptoms in 90% of patients with MG (13). If a female between the ages of 20-30 or a male older than 60 complains of generalized fatigue, eye muscle weakness, dysphagia, dystonia, and/or dysarthria MG should be considered and thymoma ruled out (1, 3, 4). This case report provides detailed descriptions and illustrations of how to recognize and treat MG, the importance of investigating for a thymoma, and current information regarding a thymectomy. Overall, even though evidence has shown the correlation between MG with thymoma, this case report depicts how a patient may present with multiple complaints yet specific to the diagnoses illustrating the importance of conducting a thorough history and physical.

Polyhedral meshes are increasingly becoming an attractive option with particular advantages over traditional meshes for certain applications. What has been missing is a robust polyhedral meshing algorithm that can handle broad classes of domains exhibiting arbitrarily curved boundaries and sharp features. In addition, the power of primal-dual mesh pairs, exemplified by Voronoi-Delaunay meshes, has been recognized as an important ingredient in numerous formulations. The VoroCrust algorithm is the first provably-correct algorithm for conforming polyhedral Voronoi meshing for non-convex and non-manifold domains with guarantees on the quality of both surface and volume elements. A robust refinement process estimates a suitable sizing field that enables the careful placement of Voronoi seeds across the surface circumventing the need for clipping and avoiding its many drawbacks. The algorithm has the flexibility of filling the interior by either structured or random samples, while preserving all sharp features in the output mesh. We demonstrate the capabilities of the algorithm on a variety of models and compare against state-of-the-art polyhedral meshing methods based on clipped Voronoi cells establishing the clear advantage of VoroCrust output., 18 pages (including appendix), 18 figures. Version without compressed images available on https://www.dropbox.com/s/qc6sot1gaujundy/VoroCrust.pdf. Supplemental materials available on https://www.dropbox.com/s/6p72h1e2ivw6kj3/VoroCrust_supplemental_materials.pdf

Background: A double-blinded, prospective, randomized, controlled study was designed to determine the intensity, duration of block, analgesic efficacy and tolerability of adding magnesium sulphate to intrathecal bupivacaine and fentanyl in partiuents scheduled for elective cesarean section.Patients and Methods: Sixty patients, age 18 to 45 years, undergo elective cesarean section under spinal anesthesia, ASA physical status I-II, singleton pregnancy and at least 36 weeks gestation. The selected patients were randomly divided into two Groups (A) control group and (B) intrathecal Mg group). Group (A) was received intrathecal 10mg (2ml) of 0.5% heavy bupivacaine plus 0.5ml (25mg) fentanyl and 0.5ml saline (will addto make a total volume 3ml). While patients in Group (B) received (2ml) of 0.5% heavy bupivacaine plus 0.5mL (25μg) fentanyl and Mg sulfate 0.75mg in 0.5ml (total volume 3ml) was injected intrathecally. Demographic da-ta,clinical data, onset and duration of sensory and motor block and also complications (hypotension, nausea and vom-iting) related to regional anesthesia were recorded. Numrical Rating Scale (NRS) was recorded every 6 hours for the next 24 hours. Rescue analgesia (ketorolac 30mg) was given when NRS was >4. Time of administration and total dose of rescue analgesia was calculated. The main results of our study showed that, there were significant increases in onset time and duration of sensory and motor block in Mg group. There were significant increase in time ofthe first dose of rescue analgesia in Mg groups than the control group. There were significant decrease in the number and dose of rescue analgesia in Mg groups than the control group.Conclusion: The addition of intrathecal magnesium sulfate to intrathecal bupivacaine plus fentanyl in patients undergoing cesarean section fasten the onset of anesthesia and prolongs its duration. Also, it prolongs the duration and quality of analgesia with reduction of the use of additional analgesia and lesser side effects.

In many geometry processing applications, it is required to improve an initial mesh in terms of multiple quality objectives. Despite the availability of several mesh generation algorithms with provable guarantees, such generated meshes may only satisfy a subset of the objectives. The conflicting nature of such objectives makes it challenging to establish similar guarantees for each combination, e.g., angle bounds and vertex count. In this paper, we describe a versatile strategy for mesh improvement by interpreting quality objectives as spatial constraints on resampling and develop a toolbox of local operators to improve the mesh while preserving desirable properties. Our strategy judiciously combines smoothing and transformation techniques allowing increased flexibility to practically achieve multiple objectives simultaneously. We apply our strategy to both planar and surface meshes demonstrating how to simplify Delaunay meshes while preserving element quality, eliminate all obtuse angles in a complex mesh, and maximize the shortest edge length in a Voronoi tessellation far better than the state-of-the-art.

Total thyroidectomy is increasingly accepted for the management of bilateral benign thyroid disorders. Postoperatively, patients require lifelong levothyroxine replacement therapy to avoid postoperative hypothyroidism, which besides the burden of compliance, has been proven to be associated with several long-term side effects. Heterotopic thyroid autotransplantation was proposed several decades ago to avoid the need for life-long postoperative replacement therapy with maintaining the autoregulatory mechanism of thyroxin production inside the body according to its needs. Available data regarding this topic in literature is relatively poor. Before applying thyroid autotransplantation on humans, several studies have been done on animals, where the autologous transplantations were found to be successful in almost all the cases, proved by follow up postoperative 8-week measurements of thyroid hormones and histopathological examination of the removed autografts. Regarding the clinical application, few trials have been done using cryopreserved in vivo, in vitro or immediately autotransplanted thyroid autografts. Satisfactory results were obtained, however, the number of these studies and the number of patients per each study was very low. Besides the study methodologies were not so consistent.

We present an all-quad meshing algorithm for general domains. We start with a strongly balanced quadtree. In contrast to snapping the quadtree corners onto the geometric domain boundaries, we move them away from the geometry. Then we intersect the moved grid with the geometry. The resulting polygons are converted into quads with midpoint subdivision. Moving away avoids creating any flat angles, either at a quadtree corner or at a geometryquadtree intersection. We are able to handle two-sided domains, and more complex topologies than prior methods. The algorithm is provably correct and robust in practice. It is cleanup-free, meaning we have angle and edge length bounds without the use of any pillowing, swapping, or smoothing. Thus, our simple algorithm is fast and predictable. This paper has better quality bounds, and the algorithm is demonstrated over more complex domains, than our prior version.

© 2016 The Eurographics Association and John Wiley & Sons Ltd. We introduce an algorithmic framework for tuning the spatial density of disks in a maximal random packing, without changing the sizing function or radii of disks. Starting from any maximal random packing such as a Maximal Poisson-disk Sampling (MPS), we iteratively relocate, inject (add), or eject (remove) disks, using a set of three successively more-aggressive local operations. We may achieve a user-defined density, either more dense or more sparse, almost up to the theoretical structured limits. The tuned samples are conflict-free, retain coverage maximality, and, except in the extremes, retain the blue noise randomness properties of the input. We change the density of the packing one disk at a time, maintaining the minimum disk separation distance and the maximum domain coverage distance required of any maximal packing. These properties are local, and we can handle spatially-varying sizing functions. Using fewer points to satisfy a sizing function improves the efficiency of some applications. We apply the framework to improve the quality of meshes, removing non-obtuse angles; and to more accurately model fiber reinforced polymers for elastic and failure simulations.

We review our recent progress on efficient algorithms for generating well-spaced samples of high dimensional data, and for exploring and characterizing these data, the underlying domain, and functions over the domain. To our knowledge, these techniques have not yet been applied to computational topology, but the possible connections are worth considering. In particular, computational topology problems often have difficulty in scaling efficiently, and these sampling techniques have the potential to drastically reduce the size of the data over which these computational topology algorithms must operate. We summarize the definition of these sample distributions; algorithms for generating them in low, moderate, and high dimensions; and applications in mesh generation, rendering, motion planning and simulation.

In this paper, we present a new algorithm for all-hex meshing of domains with multiple regions without post-processing cleanup. Our method starts with a strongly balanced octree. In contrast to snapping the grid points onto the geometric boundaries, we move points a slight distance away from the common boundaries. Then we intersect the moved grid with the geometry. This allows us to avoid creating any flat angles, and we are able to handle two-sided regions and more complex topologies than prior methods. The algorithm is robust and cleanup-free; without the use of any pillowing, swapping, or smoothing. Thus, our simple algorithm is also more predictable than prior art.

We introduce a bichromatic Delaunay quadrangulation principle by assigning the vertices of a Delaunay triangulation one of two colors, then discarding edges between vertices of the same color. We present algorithms for generating quadrangulations using this principle and simple refinements. The global vertex coloring ensures that only local refinements are needed to get all quads. This is in contrast to triangle-pairing algorithms, which get stuck with isolated triangles that require global refinement. We present two new sphere-packing algorithms for generating the colored triangulation, and we may also take as input a Delaunay refinement mesh and color it arbitrarily. These mesh non-convex planar domains with provable quality: quad angles in [10o,174o] and edges in [0.1, 2] r . The algorithms extend to curved surfaces and graded meshes. The “random” algorithm generates points with blue noise. The “advancing-front” algorithm produces large patches of boundary-aligned square tilings.