Akurasi Kriteria Voltase Elektrokardiografi Hipertrofi Ventrikel Kiri untuk Membedakan Jenis Geometri Hipertrofi Ventrikel Kiri

Directory of Open Access Journals (Sweden)

Octo Tumbur

2017-08-01

The different types of left ventricular hypertrophy geometry is associated with different risk of cardiovascular disease. Echocardiography is the gold standard for diagnosis of left ventricular hypertrophy. Electrocardiographic (ECGleft ventricular hypertrophy voltage criteria can distinguish the type of geometry of left ventricular hypertrophy. The purpose of this study to find out the role of various voltage ECG criteria to distinguish the type of geometry of left ventricle hypertrophy. A cross-sectional study doing from June to November 2015 on 100 patients in cardiology clinic and inpatient at Adam Malik Hospital, Medan, through anamnesis, body mass index  measurement, ECG and echocardiography examinations. If the Sokolow-Lyon ECG criteria for left ventricular hypertrophy did not met, normal left ventricular geometry was diagnosed with 60% sensitivity, 72.22% specificity and 71% accuracy. The eccentric left ventricular hypertrophy geometry was diagnosed if Cornel voltage was not fulfilled, with 25% sensitivity, 71.88% specificity and 55% accuracy. The concentric hypertrophy geometry was diagnosed if the RV6/V5 ratio >1, with 55.56% sensitivity, 56.36% specificity and 56% accuracy. If the RV6/V5 ratio >1 are not met, concentric hypertrophic remodeling geometry was diagnosed with a sensitivity of 55.56%, a specificity of 49.45% and an accuracy of 50%. This study also found the sensitivity and specificity for left ventricular hypertrophy in echocardiography of Sokolow-Lyon criteria were 72.22% and 60.00%, the Cornel voltage criteria with a sensitivity of 77.78% and a specificity of 70.00%, and RV6/V5 ratio criteria with a sensitivity of 51.11% and a specificity of 70.00%. The overall sensitivity and specificity was low. In conclusion, various criteria of  ECG left ventricular geometry voltage can differentiate left ventricular hypertrophy geometry types. Sokolow-Lyon and Cornell voltage criteria are more sensitive and specific than the RV6/V5 ratio.

Complexities of three dimensional part geometry. [Ambiguities in specification of pieces for manufacture

Energy Technology Data Exchange (ETDEWEB)

Stark, R.H.

1977-05-01

This report is a non-technical exposition on the ambiguities in conventional specification of the shape of a part to be manufactured and on various alternatives for representing its geometry for computer processing. It touches lightly on wire-frame and bounded surface representations and on the concept of design by volumes. It concludes that no existing computer-aided design system has yet shown its long-range superiority over he spectrum of parts and of uses to which its information base should be applicable. 9 figures.

3D-printed patient-specific applications in orthopedics

Directory of Open Access Journals (Sweden)

Wong KC

2016-10-01

Full Text Available Kwok Chuen Wong Department of Orthopedics and Traumatology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong Abstract: With advances in both medical imaging and computer programming, two-dimensional axial images can be processed into other reformatted views (sagittal and coronal and three-dimensional (3D virtual models that represent a patients’ own anatomy. This processed digital information can be analyzed in detail by orthopedic surgeons to perform patient-specific orthopedic procedures. The use of 3D printing is rising and has become more prevalent in medical applications over the last decade as surgeons and researchers are increasingly utilizing the technology’s flexibility in manufacturing objects. 3D printing is a type of manufacturing process in which materials such as plastic or metal are deposited in layers to create a 3D object from a digital model. This additive manufacturing method has the advantage of fabricating objects with complex freeform geometry, which is impossible using traditional subtractive manufacturing methods. Specifically in surgical applications, the 3D printing techniques can not only generate models that give a better understanding of the complex anatomy and pathology of the patients and aid in education and surgical training, but can also produce patient-specific surgical guides or even custom implants that are tailor-made to the surgical requirements. As the clinical workflow of the 3D printing technology continues to evolve, orthopedic surgeons should embrace the latest knowledge of the technology and incorporate it into their clinical practice for patient-specific orthopedic applications. This paper is written to help orthopedic surgeons stay up-to-date on the emerging 3D technology, starting from the acquisition of clinical imaging to 3D printing for patient-specific applications in orthopedics. It 1 presents the necessary steps to prepare the medical images that are

Patient-specific surgical planning and hemodynamic computational fluid dynamics optimization through free-form haptic anatomy editing tool (SURGEM).

Science.gov (United States)

Pekkan, Kerem; Whited, Brian; Kanter, Kirk; Sharma, Shiva; de Zelicourt, Diane; Sundareswaran, Kartik; Frakes, David; Rossignac, Jarek; Yoganathan, Ajit P

2008-11-01

The first version of an anatomy editing/surgical planning tool (SURGEM) targeting anatomical complexity and patient-specific computational fluid dynamics (CFD) analysis is presented. Novel three-dimensional (3D) shape editing concepts and human-shape interaction technologies have been integrated to facilitate interactive surgical morphology alterations, grid generation and CFD analysis. In order to implement "manual hemodynamic optimization" at the surgery planning phase for patients with congenital heart defects, these tools are applied to design and evaluate possible modifications of patient-specific anatomies. In this context, anatomies involve complex geometric topologies and tortuous 3D blood flow pathways with multiple inlets and outlets. These tools make it possible to freely deform the lumen surface and to bend and position baffles through real-time, direct manipulation of the 3D models with both hands, thus eliminating the tedious and time-consuming phase of entering the desired geometry using traditional computer-aided design (CAD) systems. The 3D models of the modified anatomies are seamlessly exported and meshed for patient-specific CFD analysis. Free-formed anatomical modifications are quantified using an in-house skeletization based cross-sectional geometry analysis tool. Hemodynamic performance of the systematically modified anatomies is compared with the original anatomy using CFD. CFD results showed the relative importance of the various surgically created features such as pouch size, vena cave to pulmonary artery (PA) flare and PA stenosis. An interactive surgical-patch size estimator is also introduced. The combined design/analysis cycle time is used for comparing and optimizing surgical plans and improvements are tabulated. The reduced cost of patient-specific shape design and analysis process, made it possible to envision large clinical studies to assess the validity of predictive patient-specific CFD simulations. In this paper, model

Patient-Specific MRI-Based Right Ventricle Models Using Different Zero-Load Diastole and Systole Geometries for Better Cardiac Stress and Strain Calculations and Pulmonary Valve Replacement Surgical Outcome Predictions.

Directory of Open Access Journals (Sweden)

Dalin Tang

Full Text Available Accurate calculation of ventricular stress and strain is critical for cardiovascular investigations. Sarcomere shortening in active contraction leads to change of ventricular zero-stress configurations during the cardiac cycle. A new model using different zero-load diastole and systole geometries was introduced to provide more accurate cardiac stress/strain calculations with potential to predict post pulmonary valve replacement (PVR surgical outcome.Cardiac magnetic resonance (CMR data were obtained from 16 patients with repaired tetralogy of Fallot prior to and 6 months after pulmonary valve replacement (8 male, 8 female, mean age 34.5 years. Patients were divided into Group 1 (n = 8 with better post PVR outcome and Group 2 (n = 8 with worse post PVR outcome based on their change in RV ejection fraction (EF. CMR-based patient-specific computational RV/LV models using one zero-load geometry (1G model and two zero-load geometries (diastole and systole, 2G model were constructed and RV wall thickness, volume, circumferential and longitudinal curvatures, mechanical stress and strain were obtained for analysis. Pairwise T-test and Linear Mixed Effect (LME model were used to determine if the differences from the 1G and 2G models were statistically significant, with the dependence of the pair-wise observations and the patient-slice clustering effects being taken into consideration. For group comparisons, continuous variables (RV volumes, WT, C- and L- curvatures, and stress and strain values were summarized as mean ± SD and compared between the outcome groups by using an unpaired Student t-test. Logistic regression analysis was used to identify potential morphological and mechanical predictors for post PVR surgical outcome.Based on results from the 16 patients, mean begin-ejection stress and strain from the 2G model were 28% and 40% higher than that from the 1G model, respectively. Using the 2G model results, RV EF changes correlated negatively with

Spinning geometry = Twisted geometry

International Nuclear Information System (INIS)

Freidel, Laurent; Ziprick, Jonathan

2014-01-01

It is well known that the SU(2)-gauge invariant phase space of loop gravity can be represented in terms of twisted geometries. These are piecewise-linear-flat geometries obtained by gluing together polyhedra, but the resulting geometries are not continuous across the faces. Here we show that this phase space can also be represented by continuous, piecewise-flat three-geometries called spinning geometries. These are composed of metric-flat three-cells glued together consistently. The geometry of each cell and the manner in which they are glued is compatible with the choice of fluxes and holonomies. We first remark that the fluxes provide each edge with an angular momentum. By studying the piecewise-flat geometries which minimize edge lengths, we show that these angular momenta can be literally interpreted as the spin of the edges: the geometries of all edges are necessarily helices. We also show that the compatibility of the gluing maps with the holonomy data results in the same conclusion. This shows that a spinning geometry represents a way to glue together the three-cells of a twisted geometry to form a continuous geometry which represents a point in the loop gravity phase space. (paper)

Magnetic resonance imaging of the ear for patient-specific reconstructive surgery.

Directory of Open Access Journals (Sweden)

Luc Nimeskern

Full Text Available INTRODUCTION: Like a fingerprint, ear shape is a unique personal feature that should be reconstructed with a high fidelity during reconstructive surgery. Ear cartilage tissue engineering (TE advantageously offers the possibility to use novel 3D manufacturing techniques to reconstruct the ear, thus allowing for a detailed auricular shape. However it also requires detailed patient-specific images of the 3D cartilage structures of the patient's intact contralateral ear (if available. Therefore the aim of this study was to develop and evaluate an imaging strategy for acquiring patient-specific ear cartilage shape, with sufficient precision and accuracy for use in a clinical setting. METHODS AND MATERIALS: Magnetic resonance imaging (MRI was performed on 14 volunteer and six cadaveric auricles and manually segmented. Reproducibility of cartilage volume (Cg.V, surface (Cg.S and thickness (Cg.Th was assessed, to determine whether raters could repeatedly define the same volume of interest. Additionally, six cadaveric auricles were harvested, scanned and segmented using the same procedure, then dissected and scanned using high resolution micro-CT. Correlation between MR and micro-CT measurements was assessed to determine accuracy. RESULTS: Good inter- and intra-rater reproducibility was observed (precision errors 0.82, but low for Cg.Th (0.95 demonstrated high accuracy. DISCUSSION AND CONCLUSION: This study demonstrated that precision and accuracy of the proposed method was high enough to detect patient-specific variation in ear cartilage geometry. The present study provides a clinical strategy to access the necessary information required for the production of 3D ear scaffolds for TE purposes, including detailed patient-specific shape. Furthermore, the protocol is applicable in daily clinical practice with existing infrastructure.

Left Ventricular Diastolic Function in Essential Hypertensive Patients: Influence of Age and Left Ventricular Geometry

Directory of Open Access Journals (Sweden)

Rosa Eduardo Cantoni

2002-01-01

Full Text Available PURPOSE - To evaluate diastolic dysfunction (DD in essential hypertension and the influence of age and cardiac geometry on this parameter. METHODS - Four hundred sixty essential hypertensive patients (HT underwent Doppler echocardiography to obtain E/A wave ratio (E/A, atrial deceleration time (ADT, and isovolumetric relaxation time (IRT. All patients were grouped according to cardiac geometric patterns (NG - normal geometry; CR - concentric remodeling; CH- concentric hypertrophy; EH - eccentric hypertrophy and to age (60 years. One hundred six normotensives (NT persons were also evaluated. RESULTS - A worsening of diastolic function in the HT compared with the NT, including HT with NG (E/A: NT - 1.38±0.03 vs HT - 1.27±0.02, p<0.01, was observed. A higher prevalence of DD occurred parallel to age and cardiac geometry also in the prehypertrophic groups (CR. Multiple regression analysis identified age as the most important predictor of DD (r²=0.30, p<0.01. CONCLUSION - DD was prevalent in this hypertensive population, being highly affected by age and less by heart structural parameters. DD is observed in incipient stages of hypertensive heart disease, and thus its early detection may help in the risk stratification of hypertensive patients.

Specification of volume and dose in radiotherapy

International Nuclear Information System (INIS)

Levernes, S.

1997-01-01

As a result of a questionnaire about dose and volume specifications in radiotherapy in the Nordic countries, a group has been set up to propose common recommendations for these countries. The proposal is partly based on ICRU 50, but with major extensions. These extensions fall into three areas: patient geometry, treatment geometry, and dose specifications. For patient geometry and set-up one need alignment markings and anatomical reference points, the latter can be divided into internal and external reference points. These points are necessary to get relationships between coordinate systems related to patient and to treatment unit. For treatment geometry the main volume will be an anatomical target volume which just encompass the clinical target volume with all its variations and movements. This anatomical volume are the most suitable volume for prescription, optimization and reporting dose. A set-up margin should be added to the beam periphery in beams-eye-view to get the minimum size and shape of the beam. For dose specification the most important parameter for homogeneous dose distributions is the arithmetic mean of dose to the anatomical target volume together with its standard deviation. In addition the dose to the ICRU reference point should be reported for intercomparison, together with minimum and maximum doses or dose volume histograms for the anatomical target volume. (author)

CMS geometry through 2020

International Nuclear Information System (INIS)

Osborne, I; Brownson, E; Eulisse, G; Jones, C D; Sexton-Kennedy, E; Lange, D J

2014-01-01

CMS faces real challenges with upgrade of the CMS detector through 2020 and beyond. One of the challenges, from the software point of view, is managing upgrade simulations with the same software release as the 2013 scenario. We present the CMS geometry description software model, its integration with the CMS event setup and core software. The CMS geometry configuration and selection is implemented in Python. The tools collect the Python configuration fragments into a script used in CMS workflow. This flexible and automated geometry configuration allows choosing either transient or persistent version of the same scenario and specific version of the same scenario. We describe how the geometries are integrated and validated, and how we define and handle different geometry scenarios in simulation and reconstruction. We discuss how to transparently manage multiple incompatible geometries in the same software release. Several examples are shown based on current implementation assuring consistent choice of scenario conditions. The consequences and implications for multiple/different code algorithms are discussed.

A Centerline Based Model Morphing Algorithm for Patient-Specific Finite Element Modelling of the Left Ventricle.

Science.gov (United States)

Behdadfar, S; Navarro, L; Sundnes, J; Maleckar, M; Ross, S; Odland, H H; Avril, S

2017-09-20

Hexahedral automatic model generation is a recurrent problem in computer vision and computational biomechanics. It may even become a challenging problem when one wants to develop a patient-specific finite-element (FE) model of the left ventricle (LV), particularly when only low resolution images are available. In the present study, a fast and efficient algorithm is presented and tested to address such a situation. A template FE hexahedral model was created for a LV geometry using a General Electric (GE) ultrasound (US) system. A system of centerline was considered for this LV mesh. Then, the nodes located over the endocardial and epicardial surfaces are respectively projected from this centerline onto the actual endocardial and epicardial surfaces reconstructed from a patient's US data. Finally, the position of the internal nodes is derived by finding the deformations with minimal elastic energy. This approach was applied to eight patients suffering from congestive heart disease. A FE analysis was performed to derive the stress induced in the LV tissue by diastolic blood pressure on each of them. Our model morphing algorithm was applied successfully and the obtained meshes showed only marginal mismatches when compared to the corresponding US geometries. The diastolic FE analyses were successfully performed in seven patients to derive the distribution of principal stresses. The original model morphing algorithm is fast and robust with low computational cost. This low cost model morphing algorithm may be highly beneficial for future patient-specific reduced-order modelling of the LV with potential application to other crucial organs.

Design and manufacturing of patient-specific orthodontic appliances by computer-aided engineering techniques.

Science.gov (United States)

Barone, Sandro; Neri, Paolo; Paoli, Alessandro; Razionale, Armando Viviano

2018-01-01

Orthodontic treatments are usually performed using fixed brackets or removable oral appliances, which are traditionally made from alginate impressions and wax registrations. Among removable devices, eruption guidance appliances are used for early orthodontic treatments in order to intercept and prevent malocclusion problems. Commercially available eruption guidance appliances, however, are symmetric devices produced using a few standard sizes. For this reason, they are not able to meet all the specific patient's needs since the actual dental anatomies present various geometries and asymmetric conditions. In this article, a computer-aided design-based methodology for the design and manufacturing of a patient-specific eruption guidance appliances is presented. The proposed approach is based on the digitalization of several steps of the overall process: from the digital reconstruction of patients' anatomies to the manufacturing of customized appliances. A finite element model has been developed to evaluate the temporomandibular joint disks stress level caused by using symmetric eruption guidance appliances with different teeth misalignment conditions. The developed model can then be used to guide the design of a patient-specific appliance with the aim at reducing the patient discomfort. At this purpose, two different customization levels are proposed in order to face both arches and single tooth misalignment issues. A low-cost manufacturing process, based on an additive manufacturing technique, is finally presented and discussed.

Creating Shape Templates for Patient Specific Biventricular Modeling in Congenital Heart Disease

Science.gov (United States)

Gilbert, Kathleen; Farrar, Genevieve; Cowan, Brett R.; Suinesiaputra, Avan; Occleshaw, Christopher; Pontré, Beau; Perry, James; Hegde, Sanjeet; Marsden, Alison; Omens, Jeff; McCulloch, Andrew; Young, Alistair A.

2018-01-01

Survival rates for infants with congenital heart disease (CHD) are improving, resulting in a growing population of adults with CHD. However, the analysis of left and right ventricular function is very time-consuming owing to the variety of congenital morphologies. Efficient customization of patient geometry and function depends on high quality shape templates specifically designed for the application. In this paper, we combine a method for creating finite element shape templates with an interactive template customization to patient MRI examinations. This enables different templates to be chosen depending on patient morphology. To demonstrate this pipeline, a new biventricular template with 162 elements was created and tested in place of an existing 82-element template. The method was able to provide fast interactive biventricular analysis with 0.31 sec per edit response time. The new template was customized to 13 CHD patients with similar biventricular topology, showing improved performance over the previous template and good agreement with clinical indices. PMID:26736353

A pull-back algorithm to determine the unloaded vascular geometry in anisotropic hyperelastic AAA passive mechanics.

Science.gov (United States)

Riveros, Fabián; Chandra, Santanu; Finol, Ender A; Gasser, T Christian; Rodriguez, Jose F

2013-04-01

Biomechanical studies on abdominal aortic aneurysms (AAA) seek to provide for better decision criteria to undergo surgical intervention for AAA repair. More accurate results can be obtained by using appropriate material models for the tissues along with accurate geometric models and more realistic boundary conditions for the lesion. However, patient-specific AAA models are generated from gated medical images in which the artery is under pressure. Therefore, identification of the AAA zero pressure geometry would allow for a more realistic estimate of the aneurysmal wall mechanics. This study proposes a novel iterative algorithm to find the zero pressure geometry of patient-specific AAA models. The methodology allows considering the anisotropic hyperelastic behavior of the aortic wall, its thickness and accounts for the presence of the intraluminal thrombus. Results on 12 patient-specific AAA geometric models indicate that the procedure is computational tractable and efficient, and preserves the global volume of the model. In addition, a comparison of the peak wall stress computed with the zero pressure and CT-based geometries during systole indicates that computations using CT-based geometric models underestimate the peak wall stress by 59 ± 64 and 47 ± 64 kPa for the isotropic and anisotropic material models of the arterial wall, respectively.

General Geometry and Geometry of Electromagnetism

OpenAIRE

Shahverdiyev, Shervgi S.

2002-01-01

It is shown that Electromagnetism creates geometry different from Riemannian geometry. General geometry including Riemannian geometry as a special case is constructed. It is proven that the most simplest special case of General Geometry is geometry underlying Electromagnetism. Action for electromagnetic field and Maxwell equations are derived from curvature function of geometry underlying Electromagnetism. And it is shown that equation of motion for a particle interacting with electromagnetic...

Sensitivity of subject-specific models to errors in musculo-skeletal geometry.

Science.gov (United States)

Carbone, V; van der Krogt, M M; Koopman, H F J M; Verdonschot, N

2012-09-21

Subject-specific musculo-skeletal models of the lower extremity are an important tool for investigating various biomechanical problems, for instance the results of surgery such as joint replacements and tendon transfers. The aim of this study was to assess the potential effects of errors in musculo-skeletal geometry on subject-specific model results. We performed an extensive sensitivity analysis to quantify the effect of the perturbation of origin, insertion and via points of each of the 56 musculo-tendon parts contained in the model. We used two metrics, namely a Local Sensitivity Index (LSI) and an Overall Sensitivity Index (OSI), to distinguish the effect of the perturbation on the predicted force produced by only the perturbed musculo-tendon parts and by all the remaining musculo-tendon parts, respectively, during a simulated gait cycle. Results indicated that, for each musculo-tendon part, only two points show a significant sensitivity: its origin, or pseudo-origin, point and its insertion, or pseudo-insertion, point. The most sensitive points belong to those musculo-tendon parts that act as prime movers in the walking movement (insertion point of the Achilles Tendon: LSI=15.56%, OSI=7.17%; origin points of the Rectus Femoris: LSI=13.89%, OSI=2.44%) and as hip stabilizers (insertion points of the Gluteus Medius Anterior: LSI=17.92%, OSI=2.79%; insertion point of the Gluteus Minimus: LSI=21.71%, OSI=2.41%). The proposed priority list provides quantitative information to improve the predictive accuracy of subject-specific musculo-skeletal models. Copyright © 2012 Elsevier Ltd. All rights reserved.

A novel patient-specific model to compute coronary fractional flow reserve.

Science.gov (United States)

Kwon, Soon-Sung; Chung, Eui-Chul; Park, Jin-Seo; Kim, Gook-Tae; Kim, Jun-Woo; Kim, Keun-Hong; Shin, Eun-Seok; Shim, Eun Bo

2014-09-01

The fractional flow reserve (FFR) is a widely used clinical index to evaluate the functional severity of coronary stenosis. A computer simulation method based on patients' computed tomography (CT) data is a plausible non-invasive approach for computing the FFR. This method can provide a detailed solution for the stenosed coronary hemodynamics by coupling computational fluid dynamics (CFD) with the lumped parameter model (LPM) of the cardiovascular system. In this work, we have implemented a simple computational method to compute the FFR. As this method uses only coronary arteries for the CFD model and includes only the LPM of the coronary vascular system, it provides simpler boundary conditions for the coronary geometry and is computationally more efficient than existing approaches. To test the efficacy of this method, we simulated a three-dimensional straight vessel using CFD coupled with the LPM. The computed results were compared with those of the LPM. To validate this method in terms of clinically realistic geometry, a patient-specific model of stenosed coronary arteries was constructed from CT images, and the computed FFR was compared with clinically measured results. We evaluated the effect of a model aorta on the computed FFR and compared this with a model without the aorta. Computationally, the model without the aorta was more efficient than that with the aorta, reducing the CPU time required for computing a cardiac cycle to 43.4%. Copyright © 2014. Published by Elsevier Ltd.

Coupling of EIT with computational lung modeling for predicting patient-specific ventilatory responses.

Science.gov (United States)

Roth, Christian J; Becher, Tobias; Frerichs, Inéz; Weiler, Norbert; Wall, Wolfgang A

2017-04-01

Providing optimal personalized mechanical ventilation for patients with acute or chronic respiratory failure is still a challenge within a clinical setting for each case anew. In this article, we integrate electrical impedance tomography (EIT) monitoring into a powerful patient-specific computational lung model to create an approach for personalizing protective ventilatory treatment. The underlying computational lung model is based on a single computed tomography scan and able to predict global airflow quantities, as well as local tissue aeration and strains for any ventilation maneuver. For validation, a novel "virtual EIT" module is added to our computational lung model, allowing to simulate EIT images based on the patient's thorax geometry and the results of our numerically predicted tissue aeration. Clinically measured EIT images are not used to calibrate the computational model. Thus they provide an independent method to validate the computational predictions at high temporal resolution. The performance of this coupling approach has been tested in an example patient with acute respiratory distress syndrome. The method shows good agreement between computationally predicted and clinically measured airflow data and EIT images. These results imply that the proposed framework can be used for numerical prediction of patient-specific responses to certain therapeutic measures before applying them to an actual patient. In the long run, definition of patient-specific optimal ventilation protocols might be assisted by computational modeling. NEW & NOTEWORTHY In this work, we present a patient-specific computational lung model that is able to predict global and local ventilatory quantities for a given patient and any selected ventilation protocol. For the first time, such a predictive lung model is equipped with a virtual electrical impedance tomography module allowing real-time validation of the computed results with the patient measurements. First promising results

Induced radioactivity in a patient-specific collimator used in proton therapy

CERN Document Server

Silari, M; Mauro, Egidio; Silari, Marco

2010-01-01

This paper discusses the activation of a patient-specific collimator, calculating dose rates, total activities and activities per unit mass of the mixture of radionuclides generated by proton irradiation in the energy range 100-250 MeV. Monte Carlo simulations were first performed for a generic case, using an approximate geometry and on the basis of assumptions on beam intensity and irradiation profile. A collimator used for a prostate cancer treatment was obtained from the MD Anderson Cancer Center (MDACC), Houston, USA, from which a number of samples were cut and analyzed by gamma spectrometry. The results of the gamma spectrometry are compared with the results of Monte Carlo simulations performed using geometrical and irradiation data specific to the unit. The assumptions made for the simulations and their impact on the results are discussed. Dose rate measurements performed in a low-background area at CERN and routine radiation protection measurements at the MDACC are also reported. It is shown that it sh...

Patient-Specific Computational Modeling

CERN Document Server

Peña, Estefanía

2012-01-01

This book addresses patient-specific modeling. It integrates computational modeling, experimental procedures, imagine clinical segmentation and mesh generation with the finite element method (FEM) to solve problems in computational biomedicine and bioengineering. Specific areas of interest include cardiovascular problems, ocular and muscular systems and soft tissue modeling. Patient-specific modeling has been the subject of serious research over the last seven years and interest in the area is continually growing and this area is expected to further develop in the near future.

Comparison of computed tomography based parametric and patient-specific finite element models of the healthy and metastatic spine using a mesh-morphing algorithm.

Science.gov (United States)

O'Reilly, Meaghan Anne; Whyne, Cari Marisa

2008-08-01

A comparative analysis of parametric and patient-specific finite element (FE) modeling of spinal motion segments. To develop patient-specific FE models of spinal motion segments using mesh-morphing methods applied to a parametric FE model. To compare strain and displacement patterns in parametric and morphed models for both healthy and metastatically involved vertebrae. Parametric FE models may be limited in their ability to fully represent patient-specific geometries and material property distributions. Generation of multiple patient-specific FE models has been limited because of computational expense. Morphing methods have been successfully used to generate multiple specimen-specific FE models of caudal rat vertebrae. FE models of a healthy and a metastatic T6-T8 spinal motion segment were analyzed with and without patient-specific material properties. Parametric and morphed models were compared using a landmark-based morphing algorithm. Morphing of the parametric FE model and including patient-specific material properties both had a strong impact on magnitudes and patterns of vertebral strain and displacement. Small but important geometric differences can be represented through morphing of parametric FE models. The mesh-morphing algorithm developed provides a rapid method for generating patient-specific FE models of spinal motion segments.

Bone Geometry, Volumetric Density, Microarchitecture and Estimated Bone Strength Assessed by HR-pQCT in Adult Patients with Hypophosphatemic Rickets

DEFF Research Database (Denmark)

Shanbhogue, Vikram Vinod; Hansen, Stinus; Folkestad, Lars

2015-01-01

Hypophosphatemic rickets (HR) is characterized by a generalized mineralization defect. Although densitometric studies have found the patients to have an elevated bone mineral density (BMD), data on bone geometry and microstructure are scarce. The aim of this cross-sectional in vivo study was to a......Hypophosphatemic rickets (HR) is characterized by a generalized mineralization defect. Although densitometric studies have found the patients to have an elevated bone mineral density (BMD), data on bone geometry and microstructure are scarce. The aim of this cross-sectional in vivo study...

Geometries

CERN Document Server

Sossinsky, A B

2012-01-01

The book is an innovative modern exposition of geometry, or rather, of geometries; it is the first textbook in which Felix Klein's Erlangen Program (the action of transformation groups) is systematically used as the basis for defining various geometries. The course of study presented is dedicated to the proposition that all geometries are created equal--although some, of course, remain more equal than others. The author concentrates on several of the more distinguished and beautiful ones, which include what he terms "toy geometries", the geometries of Platonic bodies, discrete geometries, and classical continuous geometries. The text is based on first-year semester course lectures delivered at the Independent University of Moscow in 2003 and 2006. It is by no means a formal algebraic or analytic treatment of geometric topics, but rather, a highly visual exposition containing upwards of 200 illustrations. The reader is expected to possess a familiarity with elementary Euclidean geometry, albeit those lacking t...

Geometry

CERN Document Server

Prasolov, V V

2015-01-01

This book provides a systematic introduction to various geometries, including Euclidean, affine, projective, spherical, and hyperbolic geometries. Also included is a chapter on infinite-dimensional generalizations of Euclidean and affine geometries. A uniform approach to different geometries, based on Klein's Erlangen Program is suggested, and similarities of various phenomena in all geometries are traced. An important notion of duality of geometric objects is highlighted throughout the book. The authors also include a detailed presentation of the theory of conics and quadrics, including the theory of conics for non-Euclidean geometries. The book contains many beautiful geometric facts and has plenty of problems, most of them with solutions, which nicely supplement the main text. With more than 150 figures illustrating the arguments, the book can be recommended as a textbook for undergraduate and graduate-level courses in geometry.

Torsional Newton-Cartan Geometry and Lifshitz Holography

NARCIS (Netherlands)

Christensen, M.H.; Hartong, J.; Obers, N.A.; Rollier, B.

2014-01-01

We obtain the Lifshitz UV completion in a specific model for z=2 Lifshitz geometries. We use a vielbein formalism which enables identification of all the sources as leading components of well-chosen bulk fields. We show that the geometry induced from the bulk onto the boundary is a novel extension

Combinatorial geometry in the plane

CERN Document Server

Hadwiger, Hugo; Klee, Victor

2014-01-01

Geared toward advanced undergraduates familiar with analysis and college geometry, this concise book discusses theorems on topics restricted to the plane such as convexity, coverings, and graphs. In addition to helping students cultivate rigorous thought, the text encourages the development of mathematical intuition and clarifies the nature of mathematical research.The two-part treatment begins with specific topics including integral distances, covering problems, point set geometry and convexity, simple paradoxes involving point sets, and pure combinatorics, among other subjects. The second pa

Software development for specific geometry and safe design of isotropic material multicell beams

International Nuclear Information System (INIS)

Tariq, M.M.; Ahmed, M.A.

2011-01-01

Comparison of analytical results with finite element results for analysis of isotropic material multicell beams subjected to free torsion case is the main idea of this paper. Progress in the fundamentals and applications of advanced materials and their processing technologies involves costly experiments and prototype testing for reliability. The software development for design analysis of structures with advanced materials is a low cost but challenging research. Multicell beams have important industrial applications in the aerospace and automotive sectors. This paper explains software development to test different materials in design of a multicell beam. Objective of this paper is to compute the torsional loading of multicell beams of isotropic materials for safe design in both symmetrical and asymmetrical geometries. Software has been developed in Microsoft Visual Basic. Distribution of Saint Venant shear flows, shear stresses, factors of safety, volume, mass, weight, twist, polar moment of inertia and aspect ratio for free torsion in multicell beam have been calculated using this software. The software works on four algorithms, these are, Specific geometry algorithm, material selection algorithm, factor of safety algorithm and global algorithm. User can specify new materials analytically, or choose a pre-defined material from the list, which includes, plain carbon steels, low alloy steels, stainless steels, cast irons, aluminum alloys, copper alloys, magnesium alloys, titanium alloys, precious metals and refractory metals. Although this software is restricted to multicell beam comprising of three cells, however future versions can have ability to address more complicated shapes and cases of multicell beams. Software also describes nomenclature and mathematical formulas applied to help user understand the theoretical background. User can specify geometry of multicell beam for three rectangular cells. Software computes shear flows, shear stresses, safety factors

Towards a Nano Geometry?

DEFF Research Database (Denmark)

Booss-Bavnbek, Bernhelm

2011-01-01

This paper applies I.M. Gelfand's distinction between adequate and non-adequate use of mathematical language in different contexts to the newly opened window of model-based measurements of intracellular dynamics. The specifics of geometry and dynamics on the mesoscale of cell physiology are elabo...

Modeling Patient-Specific Magnetic Drug Targeting Within the Intracranial Vasculature

Directory of Open Access Journals (Sweden)

Alexander Patronis

2018-04-01

Full Text Available Drug targeting promises to substantially enhance future therapies, for example through the focussing of chemotherapeutic drugs at the site of a tumor, thus reducing the exposure of healthy tissue to unwanted damage. Promising work on the steering of medication in the human body employs magnetic fields acting on nanoparticles made of paramagnetic materials. We develop a computational tool to aid in the optimization of the physical parameters of these particles and the magnetic configuration, estimating the fraction of particles reaching a given target site in a large patient-specific vascular system for different physiological states (heart rate, cardiac output, etc.. We demonstrate the excellent computational performance of our model by its application to the simulation of paramagnetic-nanoparticle-laden flows in a circle of Willis geometry obtained from an MRI scan. The results suggest a strong dependence of the particle density at the target site on the strength of the magnetic forcing and the velocity of the background fluid flow.

Modeling Patient-Specific Magnetic Drug Targeting Within the Intracranial Vasculature.

Science.gov (United States)

Patronis, Alexander; Richardson, Robin A; Schmieschek, Sebastian; Wylie, Brian J N; Nash, Rupert W; Coveney, Peter V

2018-01-01

Drug targeting promises to substantially enhance future therapies, for example through the focussing of chemotherapeutic drugs at the site of a tumor, thus reducing the exposure of healthy tissue to unwanted damage. Promising work on the steering of medication in the human body employs magnetic fields acting on nanoparticles made of paramagnetic materials. We develop a computational tool to aid in the optimization of the physical parameters of these particles and the magnetic configuration, estimating the fraction of particles reaching a given target site in a large patient-specific vascular system for different physiological states (heart rate, cardiac output, etc.). We demonstrate the excellent computational performance of our model by its application to the simulation of paramagnetic-nanoparticle-laden flows in a circle of Willis geometry obtained from an MRI scan. The results suggest a strong dependence of the particle density at the target site on the strength of the magnetic forcing and the velocity of the background fluid flow.

Femoral Geometry in Male Patients with Atraumatic Hip Fracture - Original Investigation

Directory of Open Access Journals (Sweden)

Gülten Tan

2007-03-01

Full Text Available Aims: Hip fracture is the most serious complication of osteoporosis and the most disabling type of fracture. In this study, we aimed to compare femoral geometry in hip fractured male patients aged more than 65 years old with age matched controls. Patients and Methods: 20 male patients with a history of nontraumatic hip fracture and 19 age-matched healthy controls were included in this study. Bone mineral density of neck and trochanter of hip were measured by DEXA. In addition to BMD, an experienced radiologist measured proximal femur geometric parameters potentially involved in bone strength. Results: Mean BMDs of trochanteric region were not significantly different between groups, but mean BMDs of neck region were statistically significantly lower in the hip fractured group. Neck shaft angle and femur shaft width were the geometric parameters found to be significantly higher in the hip fractured group. The correlation between femur geometric and the anthropometric measurements was present only in the kontrol group. Conclusion: We concluded that besides femur geometric measurements, correlation between these measurements might be an important factors for the fracture risk. (From the World of Osteoporosis 2007;13:15-8

The effect of inlet waveforms on computational hemodynamics of patient-specific intracranial aneurysms.

Science.gov (United States)

Xiang, J; Siddiqui, A H; Meng, H

2014-12-18

Due to the lack of patient-specific inlet flow waveform measurements, most computational fluid dynamics (CFD) simulations of intracranial aneurysms usually employ waveforms that are not patient-specific as inlet boundary conditions for the computational model. The current study examined how this assumption affects the predicted hemodynamics in patient-specific aneurysm geometries. We examined wall shear stress (WSS) and oscillatory shear index (OSI), the two most widely studied hemodynamic quantities that have been shown to predict aneurysm rupture, as well as maximal WSS (MWSS), energy loss (EL) and pressure loss coefficient (PLc). Sixteen pulsatile CFD simulations were carried out on four typical saccular aneurysms using 4 different waveforms and an identical inflow rate as inlet boundary conditions. Our results demonstrated that under the same mean inflow rate, different waveforms produced almost identical WSS distributions and WSS magnitudes, similar OSI distributions but drastically different OSI magnitudes. The OSI magnitude is correlated with the pulsatility index of the waveform. Furthermore, there is a linear relationship between aneurysm-averaged OSI values calculated from one waveform and those calculated from another waveform. In addition, different waveforms produced similar MWSS, EL and PLc in each aneurysm. In conclusion, inlet waveform has minimal effects on WSS, OSI distribution, MWSS, EL and PLc and a strong effect on OSI magnitude, but aneurysm-averaged OSI from different waveforms has a strong linear correlation with each other across different aneurysms, indicating that for the same aneurysm cohort, different waveforms can consistently stratify (rank) OSI of aneurysms. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of microalbuminuria on left ventricular geometry and function in hypertensive patients with type 2 diabetes mellitus.

Science.gov (United States)

Picca, Maurizio; Agozzino, Francesco; Pelosi, Giancarlo

2003-01-01

An increased urinary albumin excretion (UAE) is associated with an augmented risk of cardiovascular disease in diabetic patients and in non-diabetic subjects. Left ventricular hypertrophy has been demonstrated to be a powerful predictor of cardiovascular morbidity and mortality in arterial hypertension and when the ventricular geometry is concentric the relation is even stronger. This echocardiographic and Doppler study was designed to evaluate the influence of microalbuminuria on the left ventricular geometry and function in hypertensive patients with type 2 diabetes melitus. Forty-two patients (16 males, 26 females, mean age 59.6 +/- 6.7 years) with mild-to-moderate essential hypertension and type 2 diabetes mellitus were enrolled in the study. Twenty-one patients had an elevated UAE (group 1) and 21 a normal UAE (group 2). M-mode (under two-dimensional control) and Doppler echocardiography were performed after a 4-week washout period off antihypertensive therapy. The left ventricular mass index was found to be greater than the partition value of 51 g/m2.7 in both groups but was significantly higher (p diabetes mellitus, an elevated UAE is associated with an increased left ventricular mass index, a higher prevalence of a concentric left ventricular hypertrophy pattern, a depressed midwall systolic performance and a markedly impaired diastolic function...

Rhombicuboctahedron unit cell based scaffolds for bone regeneration: geometry optimization with a mechanobiology - driven algorithm.

Science.gov (United States)

Boccaccio, Antonio; Fiorentino, Michele; Uva, Antonio E; Laghetti, Luca N; Monno, Giuseppe

2018-02-01

In a context more and more oriented towards customized medical solutions, we propose a mechanobiology-driven algorithm to determine the optimal geometry of scaffolds for bone regeneration that is the most suited to specific boundary and loading conditions. In spite of the huge number of articles investigating different unit cells for porous biomaterials, no studies are reported in the literature that optimize the geometric parameters of such unit cells based on mechanobiological criteria. Parametric finite element models of scaffolds with rhombicuboctahedron unit cell were developed and incorporated into an optimization algorithm that combines them with a computational mechanobiological model. The algorithm perturbs iteratively the geometry of the unit cell until the best scaffold geometry is identified, i.e. the geometry that allows to maximize the formation of bone. Performances of scaffolds with rhombicuboctahedron unit cell were compared with those of other scaffolds with hexahedron unit cells. We found that scaffolds with rhombicuboctahedron unit cell are particularly suited for supporting medium-low loads, while, for higher loads, scaffolds with hexahedron unit cells are preferable. The proposed algorithm can guide the orthopaedic/surgeon in the choice of the best scaffold to be implanted in a patient-specific anatomic region. Copyright © 2017 Elsevier B.V. All rights reserved.

Just-in-time Design and Additive Manufacture of Patient-specific Medical Implants

Science.gov (United States)

Shidid, Darpan; Leary, Martin; Choong, Peter; Brandt, Milan

Recent advances in medical imaging and manufacturing science have enabled the design and production of complex, patient-specific orthopaedic implants. Additive Manufacture (AM) generates three-dimensional structures layer by layer, and is not subject to the constraints associated with traditional manufacturing methods. AM provides significant opportunities for the design of novel geometries and complex lattice structures with enhanced functional performance. However, the design and manufacture of patient-specific AM implant structures requires unique expertise in handling various optimization platforms. Furthermore, the design process for complex structures is computationally intensive. The primary aim of this research is to enable the just-in-time customisation of AM prosthesis; whereby AM implant design and manufacture be completed within the time constraints of a single surgical procedure, while minimising prosthesis mass and optimising the lattice structure to match the stiffness of the surrounding bone tissue. In this research, a design approach using raw CT scan data is applied to the AM manufacture of femoral prosthesis. Using the proposed just-in-time concept, the mass of the prosthesis was rapidly designed and manufactured while satisfying the associated structural requirements. Compressive testing of lattice structures manufactured using proposed method shows that the load carrying capacity of the resected composite bone can be recovered by up to 85% and the compressive stiffness of the AM prosthesis is statistically indistinguishable from the stiffness of the initial bone.

Optical geometry

International Nuclear Information System (INIS)

Robinson, I.; Trautman, A.

1988-01-01

The geometry of classical physics is Lorentzian; but weaker geometries are often more appropriate: null geodesics and electromagnetic fields, for example, are well known to be objects of conformal geometry. To deal with a single null congruence, or with the radiative electromagnetic fields associated with it, even less is needed: flag geometry for the first, optical geometry, with which this paper is chiefly concerned, for the second. The authors establish a natural one-to-one correspondence between optical geometries, considered locally, and three-dimensional Cauchy-Riemann structures. A number of Lorentzian geometries are shown to be equivalent from the optical point of view. For example the Goedel universe, the Taub-NUT metric and Hauser's twisting null solution have an optical geometry isomorphic to the one underlying the Robinson congruence in Minkowski space. The authors present general results on the problem of lifting a CR structure to a Lorentz manifold and, in particular, to Minkowski space; and exhibit the relevance of the deviation form to this problem

Proximal Femoral Geometry and the Risk of Fractures: Literature Review

Directory of Open Access Journals (Sweden)

N.V. Grygorieva

2016-02-01

Full Text Available This article presents the literature review of the impact of the upper third of the femur geometry (hip axis length, femoral neck angle, inter-trochanteric length, horizontal offset, thickness of the cortical bone, etc. on the risk of fractures. The article demonstrates the capabilities of techniques for measurement of hip geometry, namely conventional X-ray of pelvic bones, dual-energy X-ray absorptiometry, computed tomography. Possible correlation is shown between some genetic markers and features of the geometry of the upper third of the femur. Also, there are presented the results of own researches of age and sex characteristics of proximal hip geometry parameters in patients without fractures, as well as in patients of older age groups with internal and extraarticular femoral fractures.

Association between patellar cartilage defects and patellofemoral geometry: a matched-pair MRI comparison of patients with and without isolated patellar cartilage defects.

Science.gov (United States)

Mehl, Julian; Feucht, Matthias J; Bode, Gerrit; Dovi-Akue, David; Südkamp, Norbert P; Niemeyer, Philipp

2016-03-01

To compare the geometry of the patellofemoral joint on magnetic resonance images (MRI) between patients with isolated cartilage defects of the patella and a gender- and age-matched control group of patients without patellar cartilage defects. A total of 43 patients (17 female, 26 male) with arthroscopically verified grade III and IV patellar cartilage defects (defect group) were compared with a matched-pair control group of patients with isolated traumatic rupture of the anterior cruciate ligament without cartilage defects of the patellofemoral joint. Preoperative MRI images were analysed retrospectively with regard to patellar geometry (width, thickness, facet angle), trochlear geometry (dysplasia according to Dejour, sulcus angle, sulcus depth, lateral condyle index, trochlea facet asymmetry, lateral trochlea inclination) and patellofemoral alignment (tibial tuberosity-trochlear groove distance, patella height, lateral patella displacement, lateral patellofemoral angle, patella tilt, congruence angle). In addition to the comparison of group values, the measured values were compared to normal values reported in the literature, and the frequency of patients with pathologic findings was compared between both groups. The defect group demonstrated a significantly higher proximal chondral sulcus angle (p patellofemoral joint. In particular, a flat and shallow trochlea, trochlea dysplasia and patella alta seem to contribute to the development of patellar cartilage defects, which must be taken into consideration when planning to do surgical cartilage repair at the patella. III.

Introducing geometry concept based on history of Islamic geometry

Science.gov (United States)

Maarif, S.; Wahyudin; Raditya, A.; Perbowo, K. S.

2018-01-01

Geometry is one of the areas of mathematics interesting to discuss. Geometry also has a long history in mathematical developments. Therefore, it is important integrated historical development of geometry in the classroom to increase’ knowledge of how mathematicians earlier finding and constructing a geometric concept. Introduction geometrical concept can be started by introducing the Muslim mathematician who invented these concepts so that students can understand in detail how a concept of geometry can be found. However, the history of mathematics development, especially history of Islamic geometry today is less popular in the world of education in Indonesia. There are several concepts discovered by Muslim mathematicians that should be appreciated by the students in learning geometry. Great ideas of mathematicians Muslim can be used as study materials to supplement religious character values taught by Muslim mathematicians. Additionally, by integrating the history of geometry in teaching geometry are expected to improve motivation and geometrical understanding concept.

The association of metabolic syndrome with left ventricular mass and geometry in community-based hypertensive patients among Han Chinese

Directory of Open Access Journals (Sweden)

Shuxia Wang

2015-01-01

Full Text Available Background: The association of metabolic syndrome (MS with left ventricular (LV hypertrophy is controversial. The objective of our study was to investigate the influence of MS on LV mass and geometry in community-based hypertensive patients among Han Chinese. Materials and Methods: This study included 1733 metabolic syndrome patients according to the International Diabetes Federation (IDF definition and 2373 non-MS hypertension patients. LV hypertrophy was diagnosed by the criteria of LV mass ≥49.2 g/m 2.7 for men and 46.7 g/m 2.7 for women. LV geometric patterns (normal, concentric remodeling, concentric or eccentric hypertrophy were calculated according to LV hypertrophy and relative wall thickness. Logistic regression analysis was used to determine odds ratio (OR and 95% confidence interval (CI of MS for LV hypertrophy and LV geometry abnormality. Results: The LV mass and LV mass index were higher in the MS group than in the non-MS group. In multiple adjusted models. LV mass index, LV mass, interventricular septum, and post wall were raised with the increased number of MS disorders. MS was associated with increased LV hypertrophy risk (unadjusted OR 1.38; 95% CI 1.21-1.57; age, sex, and blood pressure (BP; adjusted OR 1.39; 95% CI 1.22-1.59. MS was also associated with increased risk of eccentric hypertrophy in male and female patients. MS was only associated with increased risk of concentric hypertrophy in female patients; and MS was not associated with concentric remodeling. Conclusion: LV mass and LV mass index were associated with the increased number of MS disorders in the Chinese community-based hypertensive population. MS was not only associated with increased LV hypertrophy risk, but also associated with concentric and eccentric LV geometry abnormality, especially in females.

Development and application of CATIA-GDML geometry builder

International Nuclear Information System (INIS)

Belogurov, S; Chernogorov, A; Ovcharenko, E; Schetinin, V; Berchun, Yu; Malzacher, P

2014-01-01

Due to conceptual difference between geometry descriptions in Computer-Aided Design (CAD) systems and particle transport Monte Carlo (MC) codes direct conversion of detector geometry in either direction is not feasible. The paper presents an update on functionality and application practice of the CATIA-GDML geometry builder first introduced at CHEP2010. This set of CATIAv5 tools has been developed for building a MC optimized GEANT4/ROOT compatible geometry based on the existing CAD model. The model can be exported via Geometry Description Markup Language (GDML). The builder allows also import and visualization of GEANT4/ROOT geometries in CATIA. The structure of a GDML file, including replicated volumes, volume assemblies and variables, is mapped into a part specification tree. A dedicated file template, a wide range of primitives, tools for measurement and implicit calculation of parameters, different types of multiple volume instantiation, mirroring, positioning and quality check have been implemented. Several use cases are discussed.

Electrodynamics and Spacetime Geometry: Foundations

Science.gov (United States)

Cabral, Francisco; Lobo, Francisco S. N.

2017-02-01

We explore the intimate connection between spacetime geometry and electrodynamics. This link is already implicit in the constitutive relations between the field strengths and excitations, which are an essential part of the axiomatic structure of electromagnetism, clearly formulated via integration theory and differential forms. We review the foundations of classical electromagnetism based on charge and magnetic flux conservation, the Lorentz force and the constitutive relations. These relations introduce the conformal part of the metric and allow the study of electrodynamics for specific spacetime geometries. At the foundational level, we discuss the possibility of generalizing the vacuum constitutive relations, by relaxing the fixed conditions of homogeneity and isotropy, and by assuming that the symmetry properties of the electro-vacuum follow the spacetime isometries. The implications of this extension are briefly discussed in the context of the intimate connection between electromagnetism and the geometry (and causal structure) of spacetime.

Geometry through history Euclidean, hyperbolic, and projective geometries

CERN Document Server

Dillon, Meighan I

2018-01-01

Presented as an engaging discourse, this textbook invites readers to delve into the historical origins and uses of geometry. The narrative traces the influence of Euclid’s system of geometry, as developed in his classic text The Elements, through the Arabic period, the modern era in the West, and up to twentieth century mathematics. Axioms and proof methods used by mathematicians from those periods are explored alongside the problems in Euclidean geometry that lead to their work. Students cultivate skills applicable to much of modern mathematics through sections that integrate concepts like projective and hyperbolic geometry with representative proof-based exercises. For its sophisticated account of ancient to modern geometries, this text assumes only a year of college mathematics as it builds towards its conclusion with algebraic curves and quaternions. Euclid’s work has affected geometry for thousands of years, so this text has something to offer to anyone who wants to broaden their appreciation for the...

SU-G-TeP3-02: Determination of Geometry-Specific Backscatter Factors for Radiobiology Studies

Energy Technology Data Exchange (ETDEWEB)

Viscariello, N; Culberson, W; Lawless, M; Kunugi, K; DeWerd, L [School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI (United States)

2016-06-15

Purpose: Radiation biology research relies on an accurate radiation dose delivered to the biological target. Large field irradiations in a cabinet irradiator may use the AAPM TG-61 protocol. This relies on an air-kerma measurement and conversion to absorbed dose to water (Dw) on the surface of a water phantom using provided backscatter factors. Cell or small animal studies differ significantly from this reference geometry. This study aims to determine the impact of the lack of full scatter conditions in four representative geometries that may be used in radiobiology studies. Methods: MCNP6 was used to model the Dw on the surface of a full scatter phantom in a validated orthovoltage x-ray reference beam. Dw in a cylindrical mouse, 100 mm Petri dish, 6-well and 96-well cell culture dishes was simulated and compared to this full scatter geometry. A reference dose rate was measured using the TG-61 protocol in a cabinet irradiator. This nominal dose rate was used to irradiate TLDs in each phantom to a given dose. Doses were obtained based on TLDs calibrated in a NIST-traceable beam. Results: Compared to the full scattering conditions, the simulated dose to water in the representative geometries were found to be underestimated by 12-26%. The discrepancy was smallest with the cylindrical mouse geometry, which most closely approximates adequate lateral- and backscatter. TLDs irradiated in the mouse and petri dish phantoms using the TG-61 determined dose rate showed similarly lower values of Dw. When corrected for this discrepancy, they agreed with the predicted Dw within 5%. Conclusion: Using the TG-61 in-air protocol and given backscatter factors to determine a reference dose rate in a biological irradiator may not be appropriate given the difference in scattering conditions between irradiation and calibration. Without accounting for this, the dose rate is overestimated and is dependent on irradiation geometry.

Retinal vascular geometry and its association to microvascular complications in patients with type 1 diabetes

DEFF Research Database (Denmark)

Rasmussen, M L; Broe, Rebecca; Frydkjaer-Olsen, Ulrik

2017-01-01

PURPOSE: To examine associations between retinal vascular geometry (tortuosity, branching coefficient [BC] and length-diameter ratio [LDR]) and diabetic proliferative retinopathy (PDR), nephropathy, and peripheral neuropathy in patients with type 1 diabetes mellitus (T1DM). METHODS: A cohort...... of patients with T1DM participated in a clinical examination in 2011. Blood and urine analyses were done and retinal images taken. PDR was defined as Early Treatment Diabetic Retinopathy Study level 61 or above, nephropathy as albumin-creatinin ratio ≥300 mg/g, and neuropathy as vibration perception threshold.......8% were male. Prevalence of PDR, nephropathy, and neuropathy were 26.5%, 6.8%, and 10.1% , respectively. Patients with increased arteriolar BC had a higher risk of nephropathy (OR: 3.10, 95% CI: [1.01-9.54]). Patients with increased venular BC had a higher risk of neuropathy (OR: 2.11, 95% CI: [1...

Evaluation of tomographic-image based geometries with PENELOPE Monte Carlo

International Nuclear Information System (INIS)

Kakoi, A.A.Y.; Galina, A.C.; Nicolucci, P.

2009-01-01

The Monte Carlo method can be used to evaluate treatment planning systems or for the determination of dose distributions in radiotherapy planning due to its accuracy and precision. In Monte Carlo simulation packages typically used in radiotherapy, however, a realistic representation of the geometry of the patient can not be used, which compromises the accuracy of the results. In this work, an algorithm for the description of geometries based on CT images of patients, developed to be used with Monte Carlo simulation package PENELOPE, is tested by simulating the dose distribution produced by a photon beam of 10 MV. The geometry simulated was based on CT images of a planning of prostate cancer. The volumes of interest in the treatment were adequately represented in the simulation geometry, allowing the algorithm to be used in verification of doses in radiotherapy treatments. (author)

Architectural geometry

KAUST Repository

Pottmann, Helmut

2014-11-26

Around 2005 it became apparent in the geometry processing community that freeform architecture contains many problems of a geometric nature to be solved, and many opportunities for optimization which however require geometric understanding. This area of research, which has been called architectural geometry, meanwhile contains a great wealth of individual contributions which are relevant in various fields. For mathematicians, the relation to discrete differential geometry is significant, in particular the integrable system viewpoint. Besides, new application contexts have become available for quite some old-established concepts. Regarding graphics and geometry processing, architectural geometry yields interesting new questions but also new objects, e.g. replacing meshes by other combinatorial arrangements. Numerical optimization plays a major role but in itself would be powerless without geometric understanding. Summing up, architectural geometry has become a rewarding field of study. We here survey the main directions which have been pursued, we show real projects where geometric considerations have played a role, and we outline open problems which we think are significant for the future development of both theory and practice of architectural geometry.

Architectural geometry

KAUST Repository

Pottmann, Helmut; Eigensatz, Michael; Vaxman, Amir; Wallner, Johannes

2014-01-01

Around 2005 it became apparent in the geometry processing community that freeform architecture contains many problems of a geometric nature to be solved, and many opportunities for optimization which however require geometric understanding. This area of research, which has been called architectural geometry, meanwhile contains a great wealth of individual contributions which are relevant in various fields. For mathematicians, the relation to discrete differential geometry is significant, in particular the integrable system viewpoint. Besides, new application contexts have become available for quite some old-established concepts. Regarding graphics and geometry processing, architectural geometry yields interesting new questions but also new objects, e.g. replacing meshes by other combinatorial arrangements. Numerical optimization plays a major role but in itself would be powerless without geometric understanding. Summing up, architectural geometry has become a rewarding field of study. We here survey the main directions which have been pursued, we show real projects where geometric considerations have played a role, and we outline open problems which we think are significant for the future development of both theory and practice of architectural geometry.

Two lectures on D-geometry and noncommutative geometry

International Nuclear Information System (INIS)

Douglas, M.R.

1999-01-01

This is a write-up of lectures given at the 1998 Spring School at the Abdus Salam ICTP. We give a conceptual introduction to D-geometry, the study of geometry as seen by D-branes in string theory, and to noncommutative geometry as it has appeared in D-brane and Matrix theory physics. (author)

Challenges and limitations of patient-specific vascular phantom fabrication using 3D Polyjet printing

Science.gov (United States)

Ionita, Ciprian N.; Mokin, Maxim; Varble, Nicole; Bednarek, Daniel R.; Xiang, Jianping; Snyder, Kenneth V.; Siddiqui, Adnan H.; Levy, Elad I.; Meng, Hui; Rudin, Stephen

2014-03-01

Additive manufacturing (3D printing) technology offers a great opportunity towards development of patient-specific vascular anatomic models, for medical device testing and physiological condition evaluation. However, the development process is not yet well established and there are various limitations depending on the printing materials, the technology and the printer resolution. Patient-specific neuro-vascular anatomy was acquired from computed tomography angiography and rotational digital subtraction angiography (DSA). The volumes were imported into a Vitrea 3D workstation (Vital Images Inc.) and the vascular lumen of various vessels and pathologies were segmented using a "marching cubes" algorithm. The results were exported as Stereo Lithographic (STL) files and were further processed by smoothing, trimming, and wall extrusion (to add a custom wall to the model). The models were printed using a Polyjet printer, Eden 260V (Objet-Stratasys). To verify the phantom geometry accuracy, the phantom was reimaged using rotational DSA, and the new data was compared with the initial patient data. The most challenging part of the phantom manufacturing was removal of support material. This aspect could be a serious hurdle in building very tortuous phantoms or small vessels. The accuracy of the printed models was very good: distance analysis showed average differences of 120 μm between the patient and the phantom reconstructed volume dimensions. Most errors were due to residual support material left in the lumen of the phantom. Despite the post-printing challenges experienced during the support cleaning, this technology could be a tremendous benefit to medical research such as in device development and testing.

Novel approach for identification of left ventricle geometry in patients with chronic heart failure, AH and IHD in combination with COPD

Directory of Open Access Journals (Sweden)

Potabashniy V.A.

2016-05-01

Full Text Available The aim of this study was to examine the direction of change of left ventricle (LV geometry in patients with chronic heart failure (CHF, arterial hypertension (AH and ischemic heart disease (IHD in combination with chronic obstructive pulmonary disease (COPD in dependence on severity of clinical signs of CHF and COPD based on recommendation of American Society of Echocardiography and European Association of Cardiovascular Images (2015. We examined 67 patients with CHF, associated with AH and stable IHD and stable COPD. By the results of this study there were determined different types of left ventricle geometry: concentric LV hypertrophy (LVH, eccentric LVH, mixed LVH, dilated LVH, dependent on blood pressure level, fibrosic and ischemic myocardial changes,, primary predominant disease – AH, IHD or COPD.

Twistor geometry

NARCIS (Netherlands)

van den Broek, P.M.

1984-01-01

The aim of this paper is to give a detailed exposition of the relation between the geometry of twistor space and the geometry of Minkowski space. The paper has a didactical purpose; no use has been made of differential geometry and cohomology.

Geometry

Indian Academy of Sciences (India)

. In the previous article we looked at the origins of synthetic and analytic geometry. More practical minded people, the builders and navigators, were studying two other aspects of geometry- trigonometry and integral calculus. These are actually ...

Impact of left ventricular geometry on prognosis in hypertensive patients with left ventricular hypertrophy (the LIFE study)

DEFF Research Database (Denmark)

Gerdts, E.; Cramariuc, D.; Simone, G. de

2008-01-01

, and myocardial infarction) in 937 hypertensive patients with LV hypertrophy during 4.8 years losartan- or atenolol-based treatment in the Losartan Intervention for Endpoint reduction in hypertension (LIFE) echocardiography substudy. METHODS AND RESULTS: LV geometry was determined from LV mass/body surface area......AIMS: Less is known about the relation between in-treatment left ventricular (LV) geometry and risk of cardiovascular events. We assessed LV geometric patterns on baseline and annual echocardiograms as time-varying predictors of the primary composite endpoint (cardiovascular death, stroke...... including LV geometric patterns as time-varying variables and adjusting for treatment, Framingham risk score, race, and time-varying systolic blood pressure, the patterns independently predicted higher risk of primary composite endpoints [HR 2.99 (1.16-7.71) for concentric remodelling, HR 1.79 (1...

Patient-specific surgical simulation.

Science.gov (United States)

Soler, Luc; Marescaux, Jacques

2008-02-01

Technological innovations of the twentieth century have provided medicine and surgery with new tools for education and therapy definition. Thus, by combining Medical Imaging and Virtual Reality, patient-specific applications providing preoperative surgical simulation have become possible.

Cerebral Aneurysm Clipping Surgery Simulation Using Patient-Specific 3D Printing and Silicone Casting.

Science.gov (United States)

Ryan, Justin R; Almefty, Kaith K; Nakaji, Peter; Frakes, David H

2016-04-01

Neurosurgery simulator development is growing as practitioners recognize the need for improved instructional and rehearsal platforms to improve procedural skills and patient care. In addition, changes in practice patterns have decreased the volume of specific cases, such as aneurysm clippings, which reduces the opportunity for operating room experience. The authors developed a hands-on, dimensionally accurate model for aneurysm clipping using patient-derived anatomic data and three-dimensional (3D) printing. Design of the model focused on reproducibility as well as adaptability to new patient geometry. A modular, reproducible, and patient-derived medical simulacrum was developed for medical learners to practice aneurysmal clipping procedures. Various forms of 3D printing were used to develop a geometrically accurate cranium and vascular tree featuring 9 patient-derived aneurysms. 3D printing in conjunction with elastomeric casting was leveraged to achieve a patient-derived brain model with tactile properties not yet available from commercial 3D printing technology. An educational pilot study was performed to gauge simulation efficacy. Through the novel manufacturing process, a patient-derived simulacrum was developed for neurovascular surgical simulation. A follow-up qualitative study suggests potential to enhance current educational programs; assessments support the efficacy of the simulacrum. The proposed aneurysm clipping simulator has the potential to improve learning experiences in surgical environment. 3D printing and elastomeric casting can produce patient-derived models for a dynamic learning environment that add value to surgical training and preparation. Copyright © 2016 Elsevier Inc. All rights reserved.

Physical properties corresponding to vortical flow geometry

Energy Technology Data Exchange (ETDEWEB)

Nakayama, K, E-mail: nakayama@aitech.ac.jp [Department of Mechanical Engineering, Aichi Institute of Technology, Toyota, Aichi 470-0392 (Japan)

2014-10-01

We examine a vortical flow geometry specified by the velocity gradient tensor ∇v, and derive properties representing the symmetry (axisymmetry or skewness) of the vortical flow in the swirl plane and a property specifying inflowing (outflowing) motion in all directions around the point. We focus on the radial and azimuthal velocities in a plane nonparallel to the eigenvector corresponding to the real eigenvalue of ∇v and show that these components are expressed as specific quadratic forms. The real and imaginary parts of the complex eigenvalues of ∇v represent averages of these eigenvalues of the quadratic forms, and are inadequate to specify the detailed flow geometry uniquely. The new properties complement specifying the precise flow geometry of the vortical flow.

Molecular geometry

CERN Document Server

Rodger, Alison

1995-01-01

Molecular Geometry discusses topics relevant to the arrangement of atoms. The book is comprised of seven chapters that tackle several areas of molecular geometry. Chapter 1 reviews the definition and determination of molecular geometry, while Chapter 2 discusses the unified view of stereochemistry and stereochemical changes. Chapter 3 covers the geometry of molecules of second row atoms, and Chapter 4 deals with the main group elements beyond the second row. The book also talks about the complexes of transition metals and f-block elements, and then covers the organometallic compounds and trans

SPANDY: a Monte Carlo program for gas target scattering geometry

International Nuclear Information System (INIS)

Jarmie, N.; Jett, J.H.; Niethammer, A.C.

1977-02-01

A Monte Carlo computer program is presented that simulates a two-slit gas target scattering geometry. The program is useful in estimating effects due to finite geometry and multiple scattering in the target foil. Details of the program are presented and experience with a specific example is discussed

A Patient-Specific Airway Branching Model for Mechanically Ventilated Patients

Directory of Open Access Journals (Sweden)

Nor Salwa Damanhuri

2014-01-01

Full Text Available Background. Respiratory mechanics models have the potential to guide mechanical ventilation. Airway branching models (ABMs were developed from classical fluid mechanics models but do not provide accurate models of in vivo behaviour. Hence, the ABM was improved to include patient-specific parameters and better model observed behaviour (ABMps. Methods. The airway pressure drop of the ABMps was compared with the well-accepted dynostatic algorithm (DSA in patients diagnosed with acute respiratory distress syndrome (ARDS. A scaling factor (α was used to equate the area under the pressure curve (AUC from the ABMps to the AUC of the DSA and was linked to patient state. Results. The ABMps recorded a median α value of 0.58 (IQR: 0.54–0.63; range: 0.45–0.66 for these ARDS patients. Significantly lower α values were found for individuals with chronic obstructive pulmonary disease (P<0.001. Conclusion. The ABMps model allows the estimation of airway pressure drop at each bronchial generation with patient-specific physiological measurements and can be generated from data measured at the bedside. The distribution of patient-specific α values indicates that the overall ABM can be readily improved to better match observed data and capture patient condition.

Symplectic and Poisson Geometry in Interaction with Analysis, Algebra and Topology & Symplectic Geometry, Noncommutative Geometry and Physics

CERN Document Server

Eliashberg, Yakov; Maeda, Yoshiaki; Symplectic, Poisson, and Noncommutative geometry

2014-01-01

Symplectic geometry originated in physics, but it has flourished as an independent subject in mathematics, together with its offspring, symplectic topology. Symplectic methods have even been applied back to mathematical physics. Noncommutative geometry has developed an alternative mathematical quantization scheme based on a geometric approach to operator algebras. Deformation quantization, a blend of symplectic methods and noncommutative geometry, approaches quantum mechanics from a more algebraic viewpoint, as it addresses quantization as a deformation of Poisson structures. This volume contains seven chapters based on lectures given by invited speakers at two May 2010 workshops held at the Mathematical Sciences Research Institute: Symplectic and Poisson Geometry in Interaction with Analysis, Algebra and Topology (honoring Alan Weinstein, one of the key figures in the field) and Symplectic Geometry, Noncommutative Geometry and Physics. The chapters include presentations of previously unpublished results and ...

Geometry of Quantum States

International Nuclear Information System (INIS)

Hook, D W

2008-01-01

A geometric framework for quantum mechanics arose during the mid 1970s when authors such as Cantoni explored the notion of generalized transition probabilities, and Kibble promoted the idea that the space of pure quantum states provides a natural quantum mechanical analogue for classical phase space. This central idea can be seen easily since the projection of Schroedinger's equation from a Hilbert space into the space of pure spaces is a set of Hamilton's equations. Over the intervening years considerable work has been carried out by a variety of authors and a mature description of quantum mechanics in geometric terms has emerged with many applications. This current offering would seem ideally placed to review the last thirty years of progress and relate this to the most recent work in quantum entanglement. Bengtsson and Zyczkowski's beautifully illustrated volume, Geometry of Quantum States (referred to as GQS from now on) attempts to cover considerable ground in its 466 pages. Its topics range from colour theory in Chapter 1 to quantum entanglement in Chapter 15-to say that this is a whirlwind tour is, perhaps, no understatement. The use of the work 'introduction' in the subtitle of GQS, might suggest to the reader that this work be viewed as a textbook and I think that this interpretation would be incorrect. The authors have chosen to present a survey of different topics with the specific aim to introduce entanglement in geometric terms-the book is not intended as a pedagogical introduction to the geometric approach to quantum mechanics. Each of the fifteen chapters is a short, and mostly self-contained, essay on a particular aspect or application of geometry in the context of quantum mechanics with entanglement being addressed specifically in the final chapter. The chapters fall into three classifications: those concerned with the mathematical background, those which discuss quantum theory and the foundational aspects of the geometric framework, and

Patient-Specific Modeling in Tomorrow's Medicine

CERN Document Server

2012-01-01

This book reviews the frontier of research and clinical applications of Patient Specific Modeling, and provides a state-of-the-art update as well as perspectives on future directions in this exciting field. The book is useful for medical physicists, biomedical engineers and other engineers who are interested in the science and technology aspects of Patient Specific Modeling, as well as for radiologists and other medical specialists who wish to be updated about the state of implementation.

Exploring Bundling Theory with Geometry

Science.gov (United States)

Eckalbar, John C.

2006-01-01

The author shows how instructors might successfully introduce students in principles and intermediate microeconomic theory classes to the topic of bundling (i.e., the selling of two or more goods as a package, rather than separately). It is surprising how much students can learn using only the tools of high school geometry. To be specific, one can…

The Common Evolution of Geometry and Architecture from a Geodetic Point of View

Science.gov (United States)

Bellone, T.; Fiermonte, F.; Mussio, L.

2017-05-01

Throughout history the link between geometry and architecture has been strong and while architects have used mathematics to construct their buildings, geometry has always been the essential tool allowing them to choose spatial shapes which are aesthetically appropriate. Sometimes it is geometry which drives architectural choices, but at other times it is architectural innovation which facilitates the emergence of new ideas in geometry. Among the best known types of geometry (Euclidean, projective, analytical, Topology, descriptive, fractal,…) those most frequently employed in architectural design are: - Euclidean Geometry - Projective Geometry - The non-Euclidean geometries. Entire architectural periods are linked to specific types of geometry. Euclidean geometry, for example, was the basis for architectural styles from Antiquity through to the Romanesque period. Perspective and Projective geometry, for their part, were important from the Gothic period through the Renaissance and into the Baroque and Neo-classical eras, while non-Euclidean geometries characterize modern architecture.

Geometry reconstruction method for patient-specific finite element models for the assessment of tibia fracture risk in osteogenesis imperfecta.

Science.gov (United States)

Caouette, Christiane; Ikin, Nicole; Villemure, Isabelle; Arnoux, Pierre-Jean; Rauch, Frank; Aubin, Carl-Éric

2017-04-01

Lower limb deformation in children with osteogenesis imperfecta (OI) impairs ambulation and may lead to fracture. Corrective surgery is based on empirical assessment criteria. The objective was to develop a reconstruction method of the tibia for OI patients that could be used as input of a comprehensive finite element model to assess fracture risks. Data were obtained from three children with OI and tibia deformities. Four pQCT scans were registered to biplanar radiographs, and a template mesh was deformed to fit the bone outline. Cortical bone thickness was computed. Sensitivity of the model to missing slices of pQCT was assessed by calculating maximal von Mises stress for a vertical hopping load case. Sensitivity of the model to ±5 % of cortical thickness measurements was assessed by calculating loads at fracture. Difference between the mesh contour and bone outline on the radiographs was below 1 mm. Removal of one pQCT slice increased maximal von Mises stress by up to 10 %. Simulated ±5 % variation of cortical bone thickness leads to variations of up to 4.1 % on predicted fracture loads. Using clinically available tibia imaging from children with OI, the developed reconstruction method allowed the building of patient-specific finite element models.

Electronic Geometry Textbook: A Geometric Textbook Knowledge Management System

OpenAIRE

Chen, Xiaoyu

2010-01-01

Electronic Geometry Textbook is a knowledge management system that manages geometric textbook knowledge to enable users to construct and share dynamic geometry textbooks interactively and efficiently. Based on a knowledge base organizing and storing the knowledge represented in specific languages, the system implements interfaces for maintaining the data representing that knowledge as well as relations among those data, for automatically generating readable documents for viewing or printing, ...

SU-F-I-38: Patient Organ Specific Dose Assessment in Coronary CT Angiograph Using Voxellaized Volume Dose Index in Monte Carlo Simulation

Energy Technology Data Exchange (ETDEWEB)

Fallal, Mohammadi Gh.; Riyahi, Alam N.; Graily, Gh. [Tehran University of Medical Scienced(TUMS), School of Medicine, Department of Nedical Physics and Biomedical Engineering, Tehran (Iran, Islamic Republic of); Paydar, R. [Iran University of Medical Sciences(IUMS), Allied Medicine Faculty, Department of radiation Sciences, Tehran (Iran, Islamic Republic of)

2016-06-15

Purpose: Clinical use of multi detector computed tomography(MDCT) in diagnosis of diseases due to high speed in data acquisition and high spatial resolution is significantly increased. Regarding to the high radiation dose in CT and necessity of patient specific radiation risk assessment, the adoption of new method in the calculation of organ dose is completely required and necessary. In this study by introducing a conversion factor, patient organ dose in thorax region based on CT image data using MC system was calculated. Methods: The geometry of x-ray tube, inherent filter, bow tie filter and collimator were designed using EGSnrc/BEAMnrc MC-system component modules according to GE-Light-speed 64-slices CT-scanner geometry. CT-scan image of patient thorax as a specific phantom was voxellised with 6.25mm3 in voxel and 64×64×20 matrix size. Dose to thorax organ include esophagus, lung, heart, breast, ribs, muscle, spine, spinal cord with imaging technical condition of prospectively-gated-coronary CT-Angiography(PGT) as a step and shoot method, were calculated. Irradiation of patient specific phantom was performed using a dedicated MC-code as DOSXYZnrc with PGT-irradiation model. The ratio of organ dose value calculated in MC-method to the volume CT dose index(CTDIvol) reported by CT-scanner machine according to PGT radiation technique has been introduced as conversion factor. Results: In PGT method, CTDIvol was 10.6mGy and Organ Dose/CTDIvol conversion factor for esophagus, lung, heart, breast, ribs, muscle, spine and spinal cord were obtained as; 0.96, 1.46, 1.2, 3.28. 6.68. 1.35, 3.41 and 0.93 respectively. Conclusion: The results showed while, underestimation of patient dose was found in dose calculation based on CTDIvol, also dose to breast is higher than the other studies. Therefore, the method in this study can be used to provide the actual patient organ dose in CT imaging based on CTDIvol in order to calculation of real effective dose(ED) based on organ dose

Specific features of time-dependent Psub(N) approximations in spherical geometry

International Nuclear Information System (INIS)

Peltzer, P.; Pucker, N.

1979-01-01

Approximations to the time-dependent linear transport equation can result in more serious distortions in the description of the actual physical situation than in the stationary problem. This is demonstrated in detail for the case of a neutron pulse in spherical geometry, treated within a P 1 approximation. One has to pay special attention to the singularity at r = 0 and to the effect of the boundary conditions. Effects similar to those shown here are also to be expected in connection with Psub(N) approximations of higher order. (Auth.)

A proposal of an open PET geometry

Energy Technology Data Exchange (ETDEWEB)

Yamaya, Taiga [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 (Japan); Inaniwa, Taku [Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Minohara, Shinichi [Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Yoshida, Eiji [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 (Japan); Inadama, Naoko [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 (Japan); Nishikido, Fumihiko [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 (Japan); Shibuya, Kengo [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 (Japan); Lam, Chih Fung [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 (Japan); Murayama, Hideo [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 (Japan)

2008-02-07

The long patient port of a PET scanner tends to put stress on patients, especially patients with claustrophobia. It also prevents doctors and technicians from taking care of patients during scanning. In this paper, we proposed an 'open PET' geometry, which consists of two axially separated detector rings. A long and continuous field-of-view (FOV) including a 360 deg. opened gap between two detector rings can be imaged enabling a fully 3D image reconstruction of all the possible lines-of-response. The open PET will become practical if iterative image reconstruction methods are applied even though image reconstruction of the open PET is analytically an incomplete problem. First we implemented a 'masked' 3D ordered subset expectation maximization (OS-EM) in which the system matrix was obtained from a long 'gapless' scanner by applying a mask to detectors corresponding to the open space. Next, in order to evaluate imaging performance of the proposed open PET geometry, we simulated a dual HR+ scanner (ring diameter of D = 827 mm, axial length of W = 154 mm x 2) separated by a variable gap. The gap W was the maximum limit to have axially continuous FOV of 3W though the maximum diameter of FOV at the central slice was limited to D/2. Artifacts, observed on both sides of the open space when the gap exceeded W, were effectively reduced by inserting detectors partially into unnecessary open spaces. We also tested the open PET geometry using experimental data obtained by the jPET-D4. The jPET-D4 is a prototype brain scanner, which has 5 rings of 24 detector blocks. We simulated the open jPET-D4 with a gap of 66 mm by eliminating 1 block-ring from experimental data. Although some artifacts were seen at both ends of the opened gap, very similar images were obtained with and without the gap. The proposed open PET geometry is expected to lead to realization of in-beam PET, which is a method for an in situ monitoring of charged particle therapy, by

Arithmetic noncommutative geometry

CERN Document Server

Marcolli, Matilde

2005-01-01

Arithmetic noncommutative geometry denotes the use of ideas and tools from the field of noncommutative geometry, to address questions and reinterpret in a new perspective results and constructions from number theory and arithmetic algebraic geometry. This general philosophy is applied to the geometry and arithmetic of modular curves and to the fibers at archimedean places of arithmetic surfaces and varieties. The main reason why noncommutative geometry can be expected to say something about topics of arithmetic interest lies in the fact that it provides the right framework in which the tools of geometry continue to make sense on spaces that are very singular and apparently very far from the world of algebraic varieties. This provides a way of refining the boundary structure of certain classes of spaces that arise in the context of arithmetic geometry, such as moduli spaces (of which modular curves are the simplest case) or arithmetic varieties (completed by suitable "fibers at infinity"), by adding boundaries...

THE COMMON EVOLUTION OF GEOMETRY AND ARCHITECTURE FROM A GEODETIC POINT OF VIEW

Directory of Open Access Journals (Sweden)

T. Bellone

2017-05-01

Full Text Available Throughout history the link between geometry and architecture has been strong and while architects have used mathematics to construct their buildings, geometry has always been the essential tool allowing them to choose spatial shapes which are aesthetically appropriate. Sometimes it is geometry which drives architectural choices, but at other times it is architectural innovation which facilitates the emergence of new ideas in geometry. Among the best known types of geometry (Euclidean, projective, analytical, Topology, descriptive, fractal,… those most frequently employed in architectural design are: – Euclidean Geometry – Projective Geometry – The non-Euclidean geometries. Entire architectural periods are linked to specific types of geometry. Euclidean geometry, for example, was the basis for architectural styles from Antiquity through to the Romanesque period. Perspective and Projective geometry, for their part, were important from the Gothic period through the Renaissance and into the Baroque and Neo-classical eras, while non-Euclidean geometries characterize modern architecture.

Higher geometry an introduction to advanced methods in analytic geometry

CERN Document Server

Woods, Frederick S

2005-01-01

For students of mathematics with a sound background in analytic geometry and some knowledge of determinants, this volume has long been among the best available expositions of advanced work on projective and algebraic geometry. Developed from Professor Woods' lectures at the Massachusetts Institute of Technology, it bridges the gap between intermediate studies in the field and highly specialized works.With exceptional thoroughness, it presents the most important general concepts and methods of advanced algebraic geometry (as distinguished from differential geometry). It offers a thorough study

Simultaneous calibration phantom commission and geometry calibration in cone beam CT

Science.gov (United States)

Xu, Yuan; Yang, Shuai; Ma, Jianhui; Li, Bin; Wu, Shuyu; Qi, Hongliang; Zhou, Linghong

2017-09-01

Geometry calibration is a vital step for describing the geometry of a cone beam computed tomography (CBCT) system and is a prerequisite for CBCT reconstruction. In current methods, calibration phantom commission and geometry calibration are divided into two independent tasks. Small errors in ball-bearing (BB) positioning in the phantom-making step will severely degrade the quality of phantom calibration. To solve this problem, we propose an integrated method to simultaneously realize geometry phantom commission and geometry calibration. Instead of assuming the accuracy of the geometry phantom, the integrated method considers BB centers in the phantom as an optimized parameter in the workflow. Specifically, an evaluation phantom and the corresponding evaluation contrast index are used to evaluate geometry artifacts for optimizing the BB coordinates in the geometry phantom. After utilizing particle swarm optimization, the CBCT geometry and BB coordinates in the geometry phantom are calibrated accurately and are then directly used for the next geometry calibration task in other CBCT systems. To evaluate the proposed method, both qualitative and quantitative studies were performed on simulated and realistic CBCT data. The spatial resolution of reconstructed images using dental CBCT can reach up to 15 line pair cm-1. The proposed method is also superior to the Wiesent method in experiments. This paper shows that the proposed method is attractive for simultaneous and accurate geometry phantom commission and geometry calibration.

Non-Riemannian geometry

CERN Document Server

Eisenhart, Luther Pfahler

2005-01-01

This concise text by a prominent mathematician deals chiefly with manifolds dominated by the geometry of paths. Topics include asymmetric and symmetric connections, the projective geometry of paths, and the geometry of sub-spaces. 1927 edition.

Geometric Transformations in Engineering Geometry

Directory of Open Access Journals (Sweden)

I. F. Borovikov

2015-01-01

Full Text Available Recently, for business purposes, in view of current trends and world experience in training engineers, research and faculty staff there has been a need to transform traditional courses of descriptive geometry into the course of engineering geometry in which the geometrical transformations have to become its main section. On the basis of critical analysis the paper gives suggestions to improve a presentation technique of this section both in the classroom and in academic literature, extend an application scope of geometrical transformations to solve the position and metric tasks and simulation of surfaces, as well as to design complex engineering configurations, which meet a number of pre-specified conditions.The article offers to make a number of considerable amendments to the terms and definitions used in the existing courses of descriptive geometry. It draws some conclusions and makes the appropriate proposals on feasibility of coordination in teaching the movement transformation in the courses of analytical and descriptive geometry. This will provide interdisciplinary team teaching and allow students to be convinced that a combination of analytical and graphic ways to solve geometric tasks is useful and reasonable.The traditional sections of learning courses need to be added with a theory of projective and bi-rational transformations. In terms of application simplicity and convenience it is enough to consider the central transformations when solving the applied tasks. These transformations contain a beam of sub-invariant (low-invariant straight lines on which the invariant curve induces non-involution and involution projectivities. The expediency of nonlinear transformations application is shown in the article by a specific example of geometric modeling of the interfacing surface "spar-blade".Implementation of these suggestions will contribute to a real transformation of a traditional course of descriptive geometry to the engineering geometry

The Geometry Conference

CERN Document Server

Bárány, Imre; Vilcu, Costin

2016-01-01

This volume presents easy-to-understand yet surprising properties obtained using topological, geometric and graph theoretic tools in the areas covered by the Geometry Conference that took place in Mulhouse, France from September 7–11, 2014 in honour of Tudor Zamfirescu on the occasion of his 70th anniversary. The contributions address subjects in convexity and discrete geometry, in distance geometry or with geometrical flavor in combinatorics, graph theory or non-linear analysis. Written by top experts, these papers highlight the close connections between these fields, as well as ties to other domains of geometry and their reciprocal influence. They offer an overview on recent developments in geometry and its border with discrete mathematics, and provide answers to several open questions. The volume addresses a large audience in mathematics, including researchers and graduate students interested in geometry and geometrical problems.

Hyperbolic geometry

CERN Document Server

Iversen, Birger

1992-01-01

Although it arose from purely theoretical considerations of the underlying axioms of geometry, the work of Einstein and Dirac has demonstrated that hyperbolic geometry is a fundamental aspect of modern physics

The Semiotic Structure of Geometry Diagrams: How Textbook Diagrams Convey Meaning

Science.gov (United States)

Dimmel, Justin K.; Herbst, Patricio G.

2015-01-01

Geometry diagrams use the visual features of specific drawn objects to convey meaning about generic mathematical entities. We examine the semiotic structure of these visual features in two parts. One, we conduct a semiotic inquiry to conceptualize geometry diagrams as mathematical texts that comprise choices from different semiotic systems. Two,…

Geometry of the Universe

International Nuclear Information System (INIS)

Gurevich, L.Eh.; Gliner, Eh.B.

1978-01-01

Problems of investigating the Universe space-time geometry are described on a popular level. Immediate space-time geometries, corresponding to three cosmologic models are considered. Space-time geometry of a closed model is the spherical Riemann geonetry, of an open model - is the Lobachevskij geometry; and of a plane model - is the Euclidean geometry. The Universe real geometry in the contemporary epoch of development is based on the data testifying to the fact that the Universe is infinitely expanding

How reliable are geometry-based building indices as thermal performance indicators?

International Nuclear Information System (INIS)

Rodrigues, Eugénio; Amaral, Ana Rita; Gaspar, Adélio Rodrigues; Gomes, Álvaro

2015-01-01

Highlights: • Geometry-based building indices are tested in different European climate regions. • Building design programs are used to randomly generate sets of simulation models. • Some indices correlate in specific climates and design programs. • Shape-based Relative Compactness presented the best correlation of all indices. • Window-to-Surface Ratio was the window-based index with best correlation. - Abstract: Architects and urban planners have been relying on geometry-based indices to design more energy efficient buildings for years. The advantage of such indices is their ease of use and capability to capture the relation of a few geometric variables with the building’s performance. However, such relation is usually found using only a few simple building models and considering only a few climate regions. This paper presents the analysis of six geometry-based building indices to determine their adequacy in eight different climate regions in Europe. For each location, three residential building design programs were used as building specifications. Two algorithms were employed to randomly generate and assess the thermal performance of three sets of 500 alternative building models. The results show that geometry-based indices only correlate with the buildings’ thermal performance according to specific climate regions and building design programs

On organizing principles of discrete differential geometry. Geometry of spheres

International Nuclear Information System (INIS)

Bobenko, Alexander I; Suris, Yury B

2007-01-01

Discrete differential geometry aims to develop discrete equivalents of the geometric notions and methods of classical differential geometry. This survey contains a discussion of the following two fundamental discretization principles: the transformation group principle (smooth geometric objects and their discretizations are invariant with respect to the same transformation group) and the consistency principle (discretizations of smooth parametrized geometries can be extended to multidimensional consistent nets). The main concrete geometric problem treated here is discretization of curvature-line parametrized surfaces in Lie geometry. Systematic use of the discretization principles leads to a discretization of curvature-line parametrization which unifies circular and conical nets.

Conformal geometry computational algorithms and engineering applications

CERN Document Server

Jin, Miao; He, Ying; Wang, Yalin

2018-01-01

This book offers an essential overview of computational conformal geometry applied to fundamental problems in specific engineering fields. It introduces readers to conformal geometry theory and discusses implementation issues from an engineering perspective.  The respective chapters explore fundamental problems in specific fields of application, and detail how computational conformal geometric methods can be used to solve them in a theoretically elegant and computationally efficient way. The fields covered include computer graphics, computer vision, geometric modeling, medical imaging, and wireless sensor networks. Each chapter concludes with a summary of the material covered and suggestions for further reading, and numerous illustrations and computational algorithms complement the text.  The book draws on courses given by the authors at the University of Louisiana at Lafayette, the State University of New York at Stony Brook, and Tsinghua University, and will be of interest to senior undergraduates, gradua...

Geometry and its applications

CERN Document Server

Meyer, Walter J

2006-01-01

Meyer''s Geometry and Its Applications, Second Edition, combines traditional geometry with current ideas to present a modern approach that is grounded in real-world applications. It balances the deductive approach with discovery learning, and introduces axiomatic, Euclidean geometry, non-Euclidean geometry, and transformational geometry. The text integrates applications and examples throughout and includes historical notes in many chapters. The Second Edition of Geometry and Its Applications is a significant text for any college or university that focuses on geometry''s usefulness in other disciplines. It is especially appropriate for engineering and science majors, as well as future mathematics teachers.* Realistic applications integrated throughout the text, including (but not limited to): - Symmetries of artistic patterns- Physics- Robotics- Computer vision- Computer graphics- Stability of architectural structures- Molecular biology- Medicine- Pattern recognition* Historical notes included in many chapters...

Mucorales-Specific T Cells in Patients with Hematologic Malignancies.

Science.gov (United States)

Potenza, Leonardo; Vallerini, Daniela; Barozzi, Patrizia; Riva, Giovanni; Gilioli, Andrea; Forghieri, Fabio; Candoni, Anna; Cesaro, Simone; Quadrelli, Chiara; Maertens, Johan; Rossi, Giulio; Morselli, Monica; Codeluppi, Mauro; Mussini, Cristina; Colaci, Elisabetta; Messerotti, Andrea; Paolini, Ambra; Maccaferri, Monica; Fantuzzi, Valeria; Del Giovane, Cinzia; Stefani, Alessandro; Morandi, Uliano; Maffei, Rossana; Marasca, Roberto; Narni, Franco; Fanin, Renato; Comoli, Patrizia; Romani, Luigina; Beauvais, Anne; Viale, Pier Luigi; Latgè, Jean Paul; Lewis, Russell E; Luppi, Mario

2016-01-01

Invasive mucormycosis (IM) is an emerging life-threatening fungal infection. It is difficult to obtain a definite diagnosis and to initiate timely intervention. Mucorales-specific T cells occur during the course of IM and are involved in the clearance of the infection. We have evaluated the feasibility of detecting Mucorales-specific T cells in hematological patients at risk for IM, and have correlated the detection of such cells with the clinical conditions of the patients. By using an enzyme linked immunospot assay, the presence of Mucorales-specific T cells in peripheral blood (PB) samples has been investigated at three time points during high-dose chemotherapy for hematologic malignancies. Mucorales-specific T cells producing interferon-γ, interleukin-10 and interleukin-4 were analysed in order to detect a correlation between the immune response and the clinical picture. Twenty-one (10.3%) of 204 patients, accounting for 32 (5.3%) of 598 PB samples, tested positive for Mucorales-specific T cells. Two groups could be identified. Group 1, including 15 patients without signs or symptoms of invasive fungal diseases (IFD), showed a predominance of Mucorales-specific T cells producing interferon-gamma. Group 2 included 6 patients with a clinical picture consistent with invasive fungal disease (IFD): 2 cases of proven IM and 4 cases of possible IFD. The proven patients had significantly higher number of Mucorales-specific T cells producing interleukin-10 and interleukin-4 and higher rates of positive samples by using derived diagnostic cut-offs when compared with the 15 patients without IFD. Mucorales-specific T cells can be detected and monitored in patients with hematologic malignancies at risk for IM. Mucorales-specific T cells polarized to the production of T helper type 2 cytokines are associated with proven IM and may be evaluated as a surrogate diagnostic marker for IM.

Mucorales-Specific T Cells in Patients with Hematologic Malignancies.

Directory of Open Access Journals (Sweden)

Leonardo Potenza

Full Text Available Invasive mucormycosis (IM is an emerging life-threatening fungal infection. It is difficult to obtain a definite diagnosis and to initiate timely intervention. Mucorales-specific T cells occur during the course of IM and are involved in the clearance of the infection. We have evaluated the feasibility of detecting Mucorales-specific T cells in hematological patients at risk for IM, and have correlated the detection of such cells with the clinical conditions of the patients.By using an enzyme linked immunospot assay, the presence of Mucorales-specific T cells in peripheral blood (PB samples has been investigated at three time points during high-dose chemotherapy for hematologic malignancies. Mucorales-specific T cells producing interferon-γ, interleukin-10 and interleukin-4 were analysed in order to detect a correlation between the immune response and the clinical picture. Twenty-one (10.3% of 204 patients, accounting for 32 (5.3% of 598 PB samples, tested positive for Mucorales-specific T cells. Two groups could be identified. Group 1, including 15 patients without signs or symptoms of invasive fungal diseases (IFD, showed a predominance of Mucorales-specific T cells producing interferon-gamma. Group 2 included 6 patients with a clinical picture consistent with invasive fungal disease (IFD: 2 cases of proven IM and 4 cases of possible IFD. The proven patients had significantly higher number of Mucorales-specific T cells producing interleukin-10 and interleukin-4 and higher rates of positive samples by using derived diagnostic cut-offs when compared with the 15 patients without IFD.Mucorales-specific T cells can be detected and monitored in patients with hematologic malignancies at risk for IM. Mucorales-specific T cells polarized to the production of T helper type 2 cytokines are associated with proven IM and may be evaluated as a surrogate diagnostic marker for IM.

Numerical simulation of magnetic nano drug targeting in patient-specific lower respiratory tract

Science.gov (United States)

Russo, Flavia; Boghi, Andrea; Gori, Fabio

2018-04-01

Magnetic nano drug targeting, with an external magnetic field, can potentially improve the drug absorption in specific locations of the body. However, the effectiveness of the procedure can be reduced due to the limitations of the magnetic field intensity. This work investigates this technique with the Computational Fluid Dynamics (CFD) approach. A single rectangular coil generates the external magnetic field. A patient-specific geometry of the Trachea, with its primary and secondary bronchi, is reconstructed from Digital Imaging and Communications in Medicine (DICOM) formatted images, throughout the Vascular Modelling Tool Kit (VMTK) software. A solver, coupling the Lagrangian dynamics of the magnetic nanoparticles with the Eulerian dynamics of the air, is used to perform the simulations. The resistive pressure, the pulsatile inlet velocity and the rectangular coil magnetic field are the boundary conditions. The dynamics of the injected particles is investigated without and with the magnetic probe. The flow field promotes particles adhesion to the tracheal wall. The particles volumetric flow rate in both cases has been calculated. The magnetic probe is shown to increase the particles flow in the target region, but at a limited extent. This behavior has been attributed to the small particle size and the probe configuration.

Beautiful geometry

CERN Document Server

Maor, Eli

2014-01-01

If you've ever thought that mathematics and art don't mix, this stunning visual history of geometry will change your mind. As much a work of art as a book about mathematics, Beautiful Geometry presents more than sixty exquisite color plates illustrating a wide range of geometric patterns and theorems, accompanied by brief accounts of the fascinating history and people behind each. With artwork by Swiss artist Eugen Jost and text by acclaimed math historian Eli Maor, this unique celebration of geometry covers numerous subjects, from straightedge-and-compass constructions to intriguing configur

Patient-specific workup of adrenal incidentalomas

Directory of Open Access Journals (Sweden)

Romy R. de Haan

Full Text Available Purpose: : To develop a clinical prediction model to predict a clinically relevant adrenal disorder for patients with adrenal incidentaloma. Materials and methods: : This retrospective study is approved by the institutional review board, with waiver of informed consent. Natural language processing is used for filtering of adrenal incidentaloma cases in all thoracic and abdominal CT reports from 2010 till 2012. A total of 635 patients are identified. Stepwise logistic regression is used to construct the prediction model. The model predicts if a patient is at risk for malignancy or hormonal hyperfunction of the adrenal gland at the moment of initial presentation, thus generates a predicted probability for every individual patient. The prediction model is evaluated on its usefulness in clinical practice using decision curve analysis (DCA based on different threshold probabilities. For patients whose predicted probability is lower than the predetermined threshold probability, further workup could be omitted. Results: : A prediction model is successfully developed, with an area under the curve (AUC of 0.78. Results of the DCA indicate that up to 11% of patients with an adrenal incidentaloma can be avoided from unnecessary workup, with a sensitivity of 100% and specificity of 11%. Conclusion: : A prediction model can accurately predict if an adrenal incidentaloma patient is at risk for malignancy or hormonal hyperfunction of the adrenal gland based on initial imaging features and patient demographics. However, with most adrenal incidentalomas labeled as nonfunctional adrenocortical adenomas requiring no further treatment, it is likely that more patients could be omitting from unnecessary diagnostics. Keywords: Adrenal incidentaloma, Patient-specific workup, Prediction model

Revolutions of Geometry

CERN Document Server

O'Leary, Michael

2010-01-01

Guides readers through the development of geometry and basic proof writing using a historical approach to the topic. In an effort to fully appreciate the logic and structure of geometric proofs, Revolutions of Geometry places proofs into the context of geometry's history, helping readers to understand that proof writing is crucial to the job of a mathematician. Written for students and educators of mathematics alike, the book guides readers through the rich history and influential works, from ancient times to the present, behind the development of geometry. As a result, readers are successfull

Analogy and Dynamic Geometry System Used to Introduce Three-Dimensional Geometry

Science.gov (United States)

Mammana, M. F.; Micale, B.; Pennisi, M.

2012-01-01

We present a sequence of classroom activities on Euclidean geometry, both plane and space geometry, used to make three dimensional geometry more catchy and simple. The activity consists of a guided research activity that leads the students to discover unexpected properties of two apparently distant geometrical entities, quadrilaterals and…

Information geometry

CERN Document Server

Ay, Nihat; Lê, Hông Vân; Schwachhöfer, Lorenz

2017-01-01

The book provides a comprehensive introduction and a novel mathematical foundation of the field of information geometry with complete proofs and detailed background material on measure theory, Riemannian geometry and Banach space theory. Parametrised measure models are defined as fundamental geometric objects, which can be both finite or infinite dimensional. Based on these models, canonical tensor fields are introduced and further studied, including the Fisher metric and the Amari-Chentsov tensor, and embeddings of statistical manifolds are investigated. This novel foundation then leads to application highlights, such as generalizations and extensions of the classical uniqueness result of Chentsov or the Cramér-Rao inequality. Additionally, several new application fields of information geometry are highlighted, for instance hierarchical and graphical models, complexity theory, population genetics, or Markov Chain Monte Carlo. The book will be of interest to mathematicians who are interested in geometry, inf...

Srna-Monte Carlo codes for proton transport simulation in combined and voxelized geometries

CERN Document Server

Ilic, R D; Stankovic, S J

2002-01-01

This paper describes new Monte Carlo codes for proton transport simulations in complex geometrical forms and in materials of different composition. The SRNA codes were developed for three dimensional (3D) dose distribution calculation in proton therapy and dosimetry. The model of these codes is based on the theory of proton multiple scattering and a simple model of compound nucleus decay. The developed package consists of two codes: SRNA-2KG and SRNA-VOX. The first code simulates proton transport in combined geometry that can be described by planes and second order surfaces. The second one uses the voxelized geometry of material zones and is specifically adopted for the application of patient computer tomography data. Transition probabilities for both codes are given by the SRNADAT program. In this paper, we will present the models and algorithms of our programs, as well as the results of the numerical experiments we have carried out applying them, along with the results of proton transport simulation obtaine...

[Partial replacement of the knee joint with patient-specific instruments and implants (ConforMIS iUni, iDuo)].

Science.gov (United States)

Beckmann, J; Steinert, A; Zilkens, C; Zeh, A; Schnurr, C; Schmitt-Sody, M; Gebauer, M

2016-04-01

Knee arthroplasty is a successful standard procedure in orthopedic surgery; however, approximately 20 % of patients are dissatisfied with the clinical results as they suffer pain and can no longer achieve the presurgery level of activity. According to the literature the reasons are inexact fitting of the prosthesis or too few anatomically formed implants resulting in less physiological kinematics of the knee joint. Reducing the number of dissatisfied patients and the corresponding number of revisions is an important goal considering the increasing need for artificial joints. In this context, patient-specific knee implants are an obvious alternative to conventional implants. For the first time implants are now matched to the individual bone and not vice versa to achieve the best possible individual situation and geometry and more structures (e.g. ligaments and bone) are preserved or only those structures are replaced which were actually destroyed by arthrosis. According to the authors view, this represents an optimal and pioneering addition to conventional implants. Patient-specific implants and the instruments needed for correct alignment and fitting can be manufactured by virtual 3D reconstruction and 3D printing based on computed tomography (CT) scans. The portfolio covers medial as well as lateral unicondylar implants, medial as well as lateral bicompartmental implants (femorotibial and patellofemoral compartments) and cruciate ligament-preserving as well as cruciate ligament-substituting total knee replacements; however, it must be explicitly emphasized that the literature is sparse and no long-term data are available.

Geometry essentials for dummies

CERN Document Server

Ryan, Mark

2011-01-01

Just the critical concepts you need to score high in geometry This practical, friendly guide focuses on critical concepts taught in a typical geometry course, from the properties of triangles, parallelograms, circles, and cylinders, to the skills and strategies you need to write geometry proofs. Geometry Essentials For Dummies is perfect for cramming or doing homework, or as a reference for parents helping kids study for exams. Get down to the basics - get a handle on the basics of geometry, from lines, segments, and angles, to vertices, altitudes, and diagonals Conque

Disease-specific self-efficacy in spasmodic dysphonia patients.

Science.gov (United States)

Hu, Amanda; Isetti, Derek; Hillel, Allen D; Waugh, Patricia; Comstock, Bryan; Meyer, Tanya K

2013-03-01

Self-efficacy (SE) is an optimistic self-belief that one can perform a novel task. This concept involves empowerment, self-esteem, and adaptation to a stressful situation. SE is a strong predictor of health behaviors. Our objectives were to study SE in spasmodic dysphonia (SD) and to develop a disease-specific SE-SD scale. Prospective study. Academic hospital. Disease-specific SE-SD items were developed with laryngologists, speech pathologists, and SD patients. These items, General SE Scale, Voice Handicap Index-10 (VHI-10), Consensus Auditory Perceptual Evaluation of Voice (CAPE-V), and Hospital Anxiety and Depression Scale (HADS), were administered to SD patients who presented for botulinum toxin injections. One hundred forty-five SD patients (mean age 59.5 ± 13.6 years) had a general SE score (Cronbach's α = 0.894) of 33.4 ± 5.2 out of 40. This was negatively correlated with HADS-A (r = -0.42, P < 0.001) and HADS-D (r = -0.42, P < .001), but not correlated with VHI-10 (r = -0.098, P = .243) and CAPE-V (r = -0.047, P = .57). Factor analysis selected 8 items from the general SE scale and 5 disease-specific SE-SD items to generate a 13-item disease-specific SE-SD scale (Cronbach's α = 0.907). Disease-specific SE-SD score was 42.1 ± 6.9 out of 52 and was negatively correlated with VHI-10 (r = -0.19, P = .005), HADS-A (r = -0.43, P < .001), and HADS-D (r = -0.57, P < .001), but not correlated with CAPE-V (r = -0.024, P = .60). SD patients established on botulinum toxin injections have high degrees of general and disease-specific SE. Patients with higher SE-SD demonstrate lower vocal handicap and lower levels of anxiety and depression. A 13-item disease-specific SE-SD scale has been developed.

Detection of electron magnetic circular dichroism signals under zone axial diffraction geometry

Energy Technology Data Exchange (ETDEWEB)

Song, Dongsheng [National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE) and The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Rusz, Jan [Department of Physics and Astronomy, Uppsala University, Box 516, S-751 20 Uppsala (Sweden); Cai, Jianwang [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Zhu, Jing, E-mail: jzhu@mail.tsinghua.edu.cn [National Center for Electron Microscopy in Beijing, Key Laboratory of Advanced Materials (MOE) and The State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

2016-10-15

EMCD (electron magnetic circular dichroism) technique provides us a new opportunity to explore magnetic properties in the transmission electron microscope. However, specific diffraction geometry is the major limitation. Only the two-beam and three-beam case are demonstrated in the experiments until now. Here, we present the more general case of zone axial (ZA) diffraction geometry through which the EMCD signals can be detected even with the very strong sensitivity to dynamical diffraction conditions. Our detailed calculations and well-controlled diffraction conditions lead to experiments in agreement with theory. The effect of dynamical diffraction conditions on EMCD signals are discussed both in theory and experiments. Moreover, with the detailed analysis of dynamical diffraction effects, we experimentally obtain the separate EMCD signals for each crystallographic site in Y{sub 3}Fe{sub 5}O{sub 12}, which is also applicable for other materials and cannot be achieved by site-specific EMCD and XMCD technique directly. Our work extends application of more general diffraction geometries and will further promote the development of EMCD technique. - Highlights: • The zone axial (ZA) diffraction geometry is presented for EMCD technique. • The detailed calculations for EMCD signals under ZA case are conducted. • The EMCD signals are obtained under the ZA case in the experiments. • The effect of dynamical effect on EMCD signals under ZA case is discussed. • Site-specific EMCD signals of Fe in Y{sub 3}Fe{sub 5}O{sub 12} are obtained by specific ZA conditions.

Hepatic blood flow distribution and performance in conventional and novel Y-graft Fontan geometries: a case series computational fluid dynamics study.

Science.gov (United States)

Yang, Weiguang; Vignon-Clementel, Irene E; Troianowski, Guillaume; Reddy, V Mohan; Feinstein, Jeffrey A; Marsden, Alison L

2012-05-01

A novel Y-shaped baffle has been proposed for the Fontan operation with promising initial results. However, previous studies have relied either on idealized models or a single patient-specific model. The objective of this study is to comprehensively compare the hemodynamic performance and hepatic blood flow distribution of the Y-graft Fontan baffle with 2 current designs using multiple patient-specific models. Y-shaped and tube-shaped grafts were virtually implanted into 5 patient-specific Glenn models forming 3 types of Fontan geometries: Y-graft, T-junction, and offset. Unsteady flow simulations were performed at rest and at varying exercise conditions. The hepatic flow distribution between the right and left lungs was carefully quantified using a particle tracking method. Other physiologically relevant parameters such as energy dissipation, superior vena cava pressure, and wall shear stress were evaluated. The Fontan geometry significantly influences the hepatic flow distribution. The Y-graft design improves the hepatic flow distribution effectively in 4 of 5 patients, whereas the T-junction and offset designs may skew as much as 97% of hepatic flow to 1 lung in 2 cases. Sensitivity studies show that changes in pulmonary flow split can affect the hepatic flow distribution dramatically but that some Y-graft and T-junction designs are relatively less sensitive than offset designs. The Y-graft design offers moderate improvements over the traditional designs in power loss and superior vena cava pressure in all patients. The Y-graft Fontan design achieves overall superior hemodynamic performance compared with traditional designs. However, the results emphasize that no one-size-fits-all solution is available that will universally benefit all patients and that designs should be customized for individual patients before clinical application. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Complex analysis and geometry

CERN Document Server

Silva, Alessandro

1993-01-01

The papers in this wide-ranging collection report on the results of investigations from a number of linked disciplines, including complex algebraic geometry, complex analytic geometry of manifolds and spaces, and complex differential geometry.

Comparison of Microinstability Properties for Stellarator Magnetic Geometries

International Nuclear Information System (INIS)

Rewoldt, G.; Ku, L.-P.; Tang, W.M.

2005-01-01

The microinstability properties of seven distinct magnetic geometries corresponding to different operating and planned stellarators with differing symmetry properties are compared. Specifically, the kinetic stability properties (linear growth rates and real frequencies) of toroidal microinstabilities (driven by ion temperature gradients and trapped-electron dynamics) are compared, as parameters are varied. The familiar ballooning representation is used to enable efficient treatment of the spatial variations along the equilibrium magnetic field lines. These studies provide useful insights for understanding the differences in the relative strengths of the instabilities caused by the differing localizations of good and bad magnetic curvature and of the presence of trapped particles. The associated differences in growth rates due to magnetic geometry are large for small values of the temperature gradient parameter n identical to d ln T/d ln n, whereas for large values of n, the mode is strongly unstable for all of the different magnetic geometries

Patient-specific hip prostheses designed by surgeons

Directory of Open Access Journals (Sweden)

Coigny Florian

2016-09-01

Full Text Available Patient-specific bone and joint replacement implants lead to better functional and aesthetic results than conventional methods [1], [2], [3]. But extracting 3D shape information from CT Data and designing individual implants is demanding and requires multiple surgeon-to-engineer interactions. For manufacturing purposes, Additive Manufacturing offers various advantages, especially for low volume manufacturing parts, such as patient specific implants. To ease these new approaches and to avoid surgeon-to-engineer interactions a new design software approach is needed which offers highly automated and user friendly planning steps.

Language-specific dysgraphia in Korean stroke patients.

Science.gov (United States)

Yoon, Ji Hye; Suh, Mee Kyung; Kim, HyangHee

2010-12-01

We investigated how changes in the writing of 14 Korean stroke patients reflect the unique features of the Korean writing system. The Korean writing system, Han-geul, has both linguistic and visuospatial/constructive characteristics. In the visuospatial construction of a syllable, the component consonant(s) and vowel(s) must be arranged from top-to-bottom and/or left-to-right within the form of a square. This syllabic organization, unique to Korean writing, may distinguish dysgraphia in Korean patients from the disorder in other languages, and reveal the effects of stroke on visuospatial/constructive abilities. We compared 2 groups of patients affected by stroke, 1 group with left hemisphere (LH) lesions and the other with right hemisphere (RH) lesions. We instructed them to write from a dictation of 90 monosyllabic stimuli, each presented with a real word cue. Patients had to repeat a target syllable and a word cue, and then to write the target syllable only. Patients with LH and RH lesions produced qualitatively different error patterns. While the LH lesion group produced primarily linguistic errors, visuospatial/constructive errors predominated in the group with RH lesions. With regard to language-specific features, these Korean patients with RH lesions produced diverse visuospatial/constructive errors not commonly observed in dysgraphia of the English language. Language-specific writing errors by Korean stroke patients reflect the unique characteristics of Korean writing, which include the arrangement of strokes and graphemes within a square syllabic form by dimensional and spatial rules. These findings support the notion that the Korean writing system possesses a language-specific nature with both linguistic and visuospatial/constructive processes. Distinctive patterns of dysgraphia in the Korean language also suggest interactivity between linguistic and visuospatial/constructive levels of processing. This study is noteworthy for its systematic description of

Code subspaces for LLM geometries

Science.gov (United States)

Berenstein, David; Miller, Alexandra

2018-03-01

We consider effective field theory around classical background geometries with a gauge theory dual, specifically those in the class of LLM geometries. These are dual to half-BPS states of N= 4 SYM. We find that the language of code subspaces is natural for discussing the set of nearby states, which are built by acting with effective fields on these backgrounds. This work extends our previous work by going beyond the strict infinite N limit. We further discuss how one can extract the topology of the state beyond N→∞ and find that, as before, uncertainty and entanglement entropy calculations provide a useful tool to do so. Finally, we discuss obstructions to writing down a globally defined metric operator. We find that the answer depends on the choice of reference state that one starts with. Therefore, within this setup, there is ambiguity in trying to write an operator that describes the metric globally.

Collaborative Middle School Geometry through Blogs and Other Web 2.0 Technologies

Science.gov (United States)

Hossain, Mokter; Wiest, Lynda R.

2013-01-01

This paper explores the use of blogs, a simple application of Web 2.0 technologies, in middle school geometry instruction. Specifically, it provides an overview of the interactive features of Web 2.0 technologies and the feasibility of using Web 2.0 technologies in geometry teaching and learning, as well as a proposed model for creating a…

SU-F-T-432: Magnetic Field Dose Effects for Various Radiation Beam Geometries for Patients Treated with Hypofractionated Partial Breast Irradiation

Energy Technology Data Exchange (ETDEWEB)

Lim-Reinders, S [Sunnybrook Odette Cancer Centre, Toronto (Canada); University of Toronto, Department of Physics (Canada); Keller, B; McCann, C; Sahgal, A; Lee, J; Kim, A [Sunnybrook Odette Cancer Centre, Toronto (Canada); University of Toronto, Department of Radiation Oncology (Canada)

2016-06-15

Purpose: Hypofractionated partial breast irradiation (HPBI) is being used at our clinic to treat inoperable breast cancer patients who have advanced disease. We are investigating how these patients could benefit from being treated in an MRI-linac, where real-time daily MRI tumor imaging and plan adaptation would be possible. As a first step, this study evaluates the dosimetric impact of the magnetic field for different radiation beam geometries on relevant OARs. Methods: Five patients previously treated using HPBI were selected. Six treatment plans were generated for each patient, evaluating three beam geometries (VMAT, IMRT, 3DCRT) with and without B{sub 0}=1.5 T. The Monaco TPS was used with the Elekta MRI-Linac beam model, where the magnetic field is orthogonal to the radiation beam. All plans were re-scaled to the same isocoverage with a prescription of 40Gy/5 to the PTV. Plans were evaluated for the effect of the magnetic field and beam modality on skin V{sub 3} {sub 0}, lung V{sub 2} {sub 0} and mean heart dose. Results: Averaged over all patients, skin V{sub 3} {sub 0}for 3DCRT was higher than VMAT and IMRT (by +22% and +21%, with B{sub 0}-ON). The magnetic field caused larger increases in skin V{sub 3} {sub 0}for 3DCRT (+8%) than VMAT (+3%) and IMRT (+4%) compared with B{sub 0}-OFF. With B{sub 0}-ON, 3DCRT had a markedly lower mean heart dose than VMAT (by 538cGy) and IMRT (by 562cGy); for lung V{sub 2} {sub 0}, 3DCRT had a marginally lower dose than VMAT (by −2.2%) and IMRT (also −2.2%). The magnetic field had minimal effect on the mean heart dose and lung V{sub 2} {sub 0} for all geometries. Conclusion: The decreased skin dose in VMAT and IMRT can potentially mitigate the effects of skin reactions for HPBI in an MRI-linac. This study illustrated that more beam angles may result in lower skin toxicity and better tumor conformality, with the trade-off of elevated heart and lung doses. We are receiving funding support from Elekta.

A Patient Specific Biomechanical Analysis of Custom Root Analogue Implant Designs on Alveolar Bone Stress: A Finite Element Study

Directory of Open Access Journals (Sweden)

David Anssari Moin

2016-01-01

Full Text Available Objectives. The aim of this study was to analyse by means of FEA the influence of 5 custom RAI designs on stress distribution of peri-implant bone and to evaluate the impact on microdisplacement for a specific patient case. Materials and Methods. A 3D surface model of a RAI for the upper right canine was constructed from the cone beam computed tomography data of one patient. Subsequently, five (targeted press-fit design modification FE models with five congruent bone models were designed: “Standard,” “Prism,” “Fins,” “Plug,” and “Bulbs,” respectively. Preprocessor software was applied to mesh the models. Two loads were applied: an oblique force (300 N and a vertical force (150 N. Analysis was performed to evaluate stress distributions and deformed contact separation at the peri-implant region. Results. The lowest von Mises stress levels were numerically observed for the Plug design. The lowest levels of contact separation were measured in the Fins model followed by the Bulbs design. Conclusions. Within the limitations of the applied methodology, adding targeted press-fit geometry to the RAI standard design will have a positive effect on stress distribution, lower concentration of bone stress, and will provide a better primary stability for this patient specific case.

Geometry

CERN Document Server

Pedoe, Dan

1988-01-01

""A lucid and masterly survey."" - Mathematics Gazette Professor Pedoe is widely known as a fine teacher and a fine geometer. His abilities in both areas are clearly evident in this self-contained, well-written, and lucid introduction to the scope and methods of elementary geometry. It covers the geometry usually included in undergraduate courses in mathematics, except for the theory of convex sets. Based on a course given by the author for several years at the University of Minnesota, the main purpose of the book is to increase geometrical, and therefore mathematical, understanding and to he

LEARNING GEOMETRY THROUGH MIMESIS AND DIGITAL CONSTRUCT

Directory of Open Access Journals (Sweden)

Maria Mion POP

2015-12-01

Full Text Available The theme proposed by us is useful to teachers and students for mathematics in the compulsory school cycle. The issues faced by school teachers/parents are the difficulty with which students read and understand the lessons/examples/synthesis in order to assimilate technical terms. The echoic and iconic memory facilitates the learning of the specific curriculum of linear, spatial and analytical geometry by the students using digital platform designed by us; it facilitates the acquiring of the theoretical elements of applied geometry by encoding-decoding, so that the teacher's role becomes the one of the advisor and not only a person who transmits the information. The utility of the program extends from mainstream schools to special schools.

Complex algebraic geometry

CERN Document Server

Kollár, János

1997-01-01

This volume contains the lectures presented at the third Regional Geometry Institute at Park City in 1993. The lectures provide an introduction to the subject, complex algebraic geometry, making the book suitable as a text for second- and third-year graduate students. The book deals with topics in algebraic geometry where one can reach the level of current research while starting with the basics. Topics covered include the theory of surfaces from the viewpoint of recent higher-dimensional developments, providing an excellent introduction to more advanced topics such as the minimal model program. Also included is an introduction to Hodge theory and intersection homology based on the simple topological ideas of Lefschetz and an overview of the recent interactions between algebraic geometry and theoretical physics, which involve mirror symmetry and string theory.

Geometry and the Design of Product Packaging

Science.gov (United States)

Cherico, Cindy M.

2011-01-01

The most common question the author's students ask is, "When will I ever use this in real life?" To address this question in her geometry classes, the author sought to create a project that would incorporate a real-world business situation with their lesson series on the surface area and volume of three-dimensional objects--specifically, prisms,…

A general three-dimensional parametric geometry of the native aortic valve and root for biomechanical modeling.

Science.gov (United States)

Haj-Ali, Rami; Marom, Gil; Ben Zekry, Sagit; Rosenfeld, Moshe; Raanani, Ehud

2012-09-21

The complex three-dimensional (3D) geometry of the native tricuspid aortic valve (AV) is represented by select parametric curves allowing for a general construction and representation of the 3D-AV structure including the cusps, commissures and sinuses. The proposed general mathematical description is performed by using three independent parametric curves, two for the cusp and one for the sinuses. These curves are used to generate different surfaces that form the structure of the AV. Additional dependent curves are also generated and utilized in this process, such as the joint curve between the cusps and the sinuses. The model's feasibility to generate patient-specific parametric geometry is examined against 3D-transesophageal echocardiogram (3D-TEE) measurements from a non-pathological AV. Computational finite-element (FE) mesh can then be easily constructed from these surfaces. Examples are given for constructing several 3D-AV geometries by estimating the needed parameters from echocardiographic measurements. The average distance (error) between the calculated geometry and the 3D-TEE measurements was only 0.78±0.63mm. The proposed general 3D parametric method is very effective in quantitatively representing a wide range of native AV structures, with and without pathology. It can also facilitate a methodical quantitative investigation over the effect of pathology and mechanical loading on these major AV parameters. Copyright © 2012 Elsevier Ltd. All rights reserved.

Analisis Keterampilan Geometri Siswa Dalam Memecahkan Masalah Geometri Berdasarkan Tingkat Berpikir Van Hiele

OpenAIRE

Muhassanah, Nuraini; Sujadi, Imam; Riyadi, Riyadi

2014-01-01

The objective of this research was to describe the VIII grade students geometry skills atSMP N 16 Surakarta in the level 0 (visualization), level 1 (analysis), and level 2 (informaldeduction) van Hiele level of thinking in solving the geometry problem. This research was aqualitative research in the form of case study analyzing deeply the students geometry skill insolving the geometry problem based on van Hiele level of thingking. The subject of this researchwas nine students of VIII grade at ...

SU-E-J-128: 3D Surface Reconstruction of a Patient Using Epipolar Geometry

Energy Technology Data Exchange (ETDEWEB)

Kotoku, J; Nakabayashi, S; Kumagai, S; Ishibashi, T; Kobayashi, T [Teikyo University, Itabashi-ku, Tokyo (Japan); Haga, A; Saotome, N [University of Tokyo Hospital, Bunkyo-ku, Tokyo (Japan); Arai, N [Teikyo University Hospital, Itabashi-ku, Tokyo (Japan)

2014-06-01

Purpose: To obtain a 3D surface data of a patient in a non-invasive way can substantially reduce the effort for the registration of patient in radiation therapy. To achieve this goal, we introduced the multiple view stereo technique, which is known to be used in a 'photo tourism' on the internet. Methods: 70 Images were taken with a digital single-lens reflex camera from different angles and positions. The camera positions and angles were inferred later in the reconstruction step. A sparse 3D reconstruction model was locating by SIFT features, which is robust for rotation and shift variance, in each image. We then found a set of correspondences between pairs of images by computing the fundamental matrix using the eight-point algorithm with RANSAC. After the pair matching, we optimized the parameter including camera positions to minimize the reprojection error by use of bundle adjustment technique (non-linear optimization). As a final step, we performed dense reconstruction and associate a color with each point using the library of PMVS. Results: Surface data were reconstructed well by visual inspection. The human skin is reconstructed well, althogh the reconstruction was time-consuming for direct use in daily clinical practice. Conclusion: 3D reconstruction using multi view stereo geometry is a promising tool for reducing the effort of patient setup. This work was supported by JSPS KAKENHI(25861128)

SU-E-J-128: 3D Surface Reconstruction of a Patient Using Epipolar Geometry

International Nuclear Information System (INIS)

Kotoku, J; Nakabayashi, S; Kumagai, S; Ishibashi, T; Kobayashi, T; Haga, A; Saotome, N; Arai, N

2014-01-01

Purpose: To obtain a 3D surface data of a patient in a non-invasive way can substantially reduce the effort for the registration of patient in radiation therapy. To achieve this goal, we introduced the multiple view stereo technique, which is known to be used in a 'photo tourism' on the internet. Methods: 70 Images were taken with a digital single-lens reflex camera from different angles and positions. The camera positions and angles were inferred later in the reconstruction step. A sparse 3D reconstruction model was locating by SIFT features, which is robust for rotation and shift variance, in each image. We then found a set of correspondences between pairs of images by computing the fundamental matrix using the eight-point algorithm with RANSAC. After the pair matching, we optimized the parameter including camera positions to minimize the reprojection error by use of bundle adjustment technique (non-linear optimization). As a final step, we performed dense reconstruction and associate a color with each point using the library of PMVS. Results: Surface data were reconstructed well by visual inspection. The human skin is reconstructed well, althogh the reconstruction was time-consuming for direct use in daily clinical practice. Conclusion: 3D reconstruction using multi view stereo geometry is a promising tool for reducing the effort of patient setup. This work was supported by JSPS KAKENHI(25861128)

From Patient-Specific Mathematical Neuro-Oncology to Precision Medicine

Directory of Open Access Journals (Sweden)

Anne eBaldock

2013-04-01

Full Text Available Gliomas are notoriously aggressive, malignant brain tumors that have variable response to treatment. These patients often have poor prognosis, informed primarily by histopathology. Mathematical neuro-oncology (MNO is a young and burgeoning field that leverages mathematical models to predict and quantify response to therapies. These mathematical models can form the basis of modern precision medicine approaches to tailor therapy in a patient-specific manner. Patient specific models (PSMs can be used to overcome imaging limitations, improve prognostic predictions, stratify patients and assess treatment response in silico. The information gleaned from such models can aid in the construction and efficacy of clinical trials and treatment protocols, accelerating the pace of clinical research in the war on cancer. This review focuses on the growing translation of PSM to clinical neuro-oncology. It will also provide a forward-looking view on a new era of patient-specific mathematical neuro-oncology.

Algorithms in Algebraic Geometry

CERN Document Server

Dickenstein, Alicia; Sommese, Andrew J

2008-01-01

In the last decade, there has been a burgeoning of activity in the design and implementation of algorithms for algebraic geometric computation. Some of these algorithms were originally designed for abstract algebraic geometry, but now are of interest for use in applications and some of these algorithms were originally designed for applications, but now are of interest for use in abstract algebraic geometry. The workshop on Algorithms in Algebraic Geometry that was held in the framework of the IMA Annual Program Year in Applications of Algebraic Geometry by the Institute for Mathematics and Its

Non-Euclidean geometry

CERN Document Server

Kulczycki, Stefan

2008-01-01

This accessible approach features two varieties of proofs: stereometric and planimetric, as well as elementary proofs that employ only the simplest properties of the plane. A short history of geometry precedes a systematic exposition of the principles of non-Euclidean geometry.Starting with fundamental assumptions, the author examines the theorems of Hjelmslev, mapping a plane into a circle, the angle of parallelism and area of a polygon, regular polygons, straight lines and planes in space, and the horosphere. Further development of the theory covers hyperbolic functions, the geometry of suff

Sums over geometries and improvements on the mean field approximation

International Nuclear Information System (INIS)

Sacksteder, Vincent E. IV

2007-01-01

The saddle points of a Lagrangian due to Efetov are analyzed. This Lagrangian was originally proposed as a tool for calculating systematic corrections to the Bethe approximation, a mean-field approximation which is important in statistical mechanics, glasses, coding theory, and combinatorial optimization. Detailed analysis shows that the trivial saddle point generates a sum over geometries reminiscent of dynamically triangulated quantum gravity, which suggests new possibilities to design sums over geometries for the specific purpose of obtaining improved mean-field approximations to D-dimensional theories. In the case of the Efetov theory, the dominant geometries are locally treelike, and the sum over geometries diverges in a way that is similar to quantum gravity's divergence when all topologies are included. Expertise from the field of dynamically triangulated quantum gravity about sums over geometries may be able to remedy these defects and fulfill the Efetov theory's original promise. The other saddle points of the Efetov Lagrangian are also analyzed; the Hessian at these points is nonnormal and pseudo-Hermitian, which is unusual for bosonic theories. The standard formula for Gaussian integrals is generalized to nonnormal kernels

Geometry on the space of geometries

International Nuclear Information System (INIS)

Christodoulakis, T.; Zanelli, J.

1988-06-01

We discuss the geometric structure of the configuration space of pure gravity. This is an infinite dimensional manifold, M, where each point represents one spatial geometry g ij (x). The metric on M is dictated by geometrodynamics, and from it, the Christoffel symbols and Riemann tensor can be found. A ''free geometry'' tracing a geodesic on the manifold describes the time evolution of space in the strong gravity limit. In a regularization previously introduced by the authors, it is found that M does not have the same dimensionality, D, everywhere, and that D is not a scalar, although it is covariantly constant. In this regularization, it is seen that the path integral measure can be absorbed in a renormalization of the cosmological constant. (author). 19 refs

A Lorentzian quantum geometry

Energy Technology Data Exchange (ETDEWEB)

Grotz, Andreas

2011-10-07

In this thesis, a formulation of a Lorentzian quantum geometry based on the framework of causal fermion systems is proposed. After giving the general definition of causal fermion systems, we deduce space-time as a topological space with an underlying causal structure. Restricting attention to systems of spin dimension two, we derive the objects of our quantum geometry: the spin space, the tangent space endowed with a Lorentzian metric, connection and curvature. In order to get the correspondence to classical differential geometry, we construct examples of causal fermion systems by regularizing Dirac sea configurations in Minkowski space and on a globally hyperbolic Lorentzian manifold. When removing the regularization, the objects of our quantum geometry reduce to the common objects of spin geometry on Lorentzian manifolds, up to higher order curvature corrections.

A Lorentzian quantum geometry

International Nuclear Information System (INIS)

Grotz, Andreas

2011-01-01

In this thesis, a formulation of a Lorentzian quantum geometry based on the framework of causal fermion systems is proposed. After giving the general definition of causal fermion systems, we deduce space-time as a topological space with an underlying causal structure. Restricting attention to systems of spin dimension two, we derive the objects of our quantum geometry: the spin space, the tangent space endowed with a Lorentzian metric, connection and curvature. In order to get the correspondence to classical differential geometry, we construct examples of causal fermion systems by regularizing Dirac sea configurations in Minkowski space and on a globally hyperbolic Lorentzian manifold. When removing the regularization, the objects of our quantum geometry reduce to the common objects of spin geometry on Lorentzian manifolds, up to higher order curvature corrections.

Patient specific ankle-foot orthoses using rapid prototyping.

Science.gov (United States)

Mavroidis, Constantinos; Ranky, Richard G; Sivak, Mark L; Patritti, Benjamin L; DiPisa, Joseph; Caddle, Alyssa; Gilhooly, Kara; Govoni, Lauren; Sivak, Seth; Lancia, Michael; Drillio, Robert; Bonato, Paolo

2011-01-12

Prefabricated orthotic devices are currently designed to fit a range of patients and therefore they do not provide individualized comfort and function. Custom-fit orthoses are superior to prefabricated orthotic devices from both of the above-mentioned standpoints. However, creating a custom-fit orthosis is a laborious and time-intensive manual process performed by skilled orthotists. Besides, adjustments made to both prefabricated and custom-fit orthoses are carried out in a qualitative manner. So both comfort and function can potentially suffer considerably. A computerized technique for fabricating patient-specific orthotic devices has the potential to provide excellent comfort and allow for changes in the standard design to meet the specific needs of each patient. In this paper, 3D laser scanning is combined with rapid prototyping to create patient-specific orthoses. A novel process was engineered to utilize patient-specific surface data of the patient anatomy as a digital input, manipulate the surface data to an optimal form using Computer Aided Design (CAD) software, and then download the digital output from the CAD software to a rapid prototyping machine for fabrication. Two AFOs were rapidly prototyped to demonstrate the proposed process. Gait analysis data of a subject wearing the AFOs indicated that the rapid prototyped AFOs performed comparably to the prefabricated polypropylene design. The rapidly prototyped orthoses fabricated in this study provided good fit of the subject's anatomy compared to a prefabricated AFO while delivering comparable function (i.e. mechanical effect on the biomechanics of gait). The rapid fabrication capability is of interest because it has potential for decreasing fabrication time and cost especially when a replacement of the orthosis is required.

Programming system for analytic geometry

International Nuclear Information System (INIS)

Raymond, Jacques

1970-01-01

After having outlined the characteristics of computing centres which do not comply with engineering tasks, notably the time required by all different tasks to be performed when developing a software (assembly, compilation, link edition, loading, run), and identified constraints specific to engineering, the author identifies the characteristics a programming system should have to suit engineering tasks. He discussed existing conversational systems and their programming language, and their main drawbacks. Then, he presents a system which aims at facilitating programming and addressing problems of analytic geometry and trigonometry

Geometry and Combinatorics

DEFF Research Database (Denmark)

Kokkendorff, Simon Lyngby

2002-01-01

The subject of this Ph.D.-thesis is somewhere in between continuous and discrete geometry. Chapter 2 treats the geometry of finite point sets in semi-Riemannian hyperquadrics,using a matrix whose entries are a trigonometric function of relative distances in a given point set. The distance...... to the geometry of a simplex in a semi-Riemannian hyperquadric. In chapter 3 we study which finite metric spaces that are realizable in a hyperbolic space in the limit where curvature goes to -∞. We show that such spaces are the so called leaf spaces, the set of degree 1 vertices of weighted trees. We also...... establish results on the limiting geometry of such an isometrically realized leaf space simplex in hyperbolic space, when curvature goes to -∞. Chapter 4 discusses negative type of metric spaces. We give a measure theoretic treatment of this concept and related invariants. The theory developed...

Geometry and billiards

CERN Document Server

Tabachnikov, Serge

2005-01-01

Mathematical billiards describe the motion of a mass point in a domain with elastic reflections off the boundary or, equivalently, the behavior of rays of light in a domain with ideally reflecting boundary. From the point of view of differential geometry, the billiard flow is the geodesic flow on a manifold with boundary. This book is devoted to billiards in their relation with differential geometry, classical mechanics, and geometrical optics. The topics covered include variational principles of billiard motion, symplectic geometry of rays of light and integral geometry, existence and nonexistence of caustics, optical properties of conics and quadrics and completely integrable billiards, periodic billiard trajectories, polygonal billiards, mechanisms of chaos in billiard dynamics, and the lesser-known subject of dual (or outer) billiards. The book is based on an advanced undergraduate topics course (but contains more material than can be realistically taught in one semester). Although the minimum prerequisit...

Drawing Dynamic Geometry Figures Online with Natural Language for Junior High School Geometry

Science.gov (United States)

Wong, Wing-Kwong; Yin, Sheng-Kai; Yang, Chang-Zhe

2012-01-01

This paper presents a tool for drawing dynamic geometric figures by understanding the texts of geometry problems. With the tool, teachers and students can construct dynamic geometric figures on a web page by inputting a geometry problem in natural language. First we need to build the knowledge base for understanding geometry problems. With the…

Experimental and Theoretical Methods in Algebra, Geometry and Topology

CERN Document Server

Veys, Willem; Bridging Algebra, Geometry, and Topology

2014-01-01

Algebra, geometry and topology cover a variety of different, but intimately related research fields in modern mathematics. This book focuses on specific aspects of this interaction. The present volume contains refereed papers which were presented at the International Conference “Experimental and Theoretical Methods in Algebra, Geometry and Topology”, held in Eforie Nord (near Constanta), Romania, during 20-25 June 2013. The conference was devoted to the 60th anniversary of the distinguished Romanian mathematicians Alexandru Dimca and Ştefan Papadima. The selected papers consist of original research work and a survey paper. They are intended for a large audience, including researchers and graduate students interested in algebraic geometry, combinatorics, topology, hyperplane arrangements and commutative algebra. The papers are written by well-known experts from different fields of mathematics, affiliated to universities from all over the word, they cover a broad range of topics and explore the research f...

Numerical simulation of magnetic nano drug targeting in a patient-specific coeliac trunk

Science.gov (United States)

Boghi, Andrea; Russo, Flavia; Gori, Fabio

2017-09-01

Magnetic nano drug targeting, through the use of an external magnetic field, is a new technique for the treatment of several diseases, which can potentially avoid the dispersion of drugs in undesired locations of the body. Nevertheless, due to the limitations on the intensity of the magnetic field applied, the hydrodynamic forces can reduce the effectiveness of the procedure. This technique is studied in this paper with the Computational Fluid Dynamics (CFD), focusing on the influence of the magnetic probe position, and the direction of the circulating electric current. A single rectangular coil is used to generate the external magnetic field. A patient-specific geometry of the coeliac trunk is reconstructed from DICOM images, with the use of VMTK. A new solver, coupling the Lagrangian dynamics of the nanoparticles with the Eulerian dynamics of the blood, is implemented in OpenFOAM to perform the simulations. The resistive pressure, the Womersley's profile for the inlet velocity and the magnetic field of a rectangular coil are implemented in the software as boundary conditions. The results show the influence of the position of the probe, as well as the limitations associated with the rectangular coil configuration.

Patient specific ankle-foot orthoses using rapid prototyping

Directory of Open Access Journals (Sweden)

Sivak Seth

2011-01-01

Full Text Available Abstract Background Prefabricated orthotic devices are currently designed to fit a range of patients and therefore they do not provide individualized comfort and function. Custom-fit orthoses are superior to prefabricated orthotic devices from both of the above-mentioned standpoints. However, creating a custom-fit orthosis is a laborious and time-intensive manual process performed by skilled orthotists. Besides, adjustments made to both prefabricated and custom-fit orthoses are carried out in a qualitative manner. So both comfort and function can potentially suffer considerably. A computerized technique for fabricating patient-specific orthotic devices has the potential to provide excellent comfort and allow for changes in the standard design to meet the specific needs of each patient. Methods In this paper, 3D laser scanning is combined with rapid prototyping to create patient-specific orthoses. A novel process was engineered to utilize patient-specific surface data of the patient anatomy as a digital input, manipulate the surface data to an optimal form using Computer Aided Design (CAD software, and then download the digital output from the CAD software to a rapid prototyping machine for fabrication. Results Two AFOs were rapidly prototyped to demonstrate the proposed process. Gait analysis data of a subject wearing the AFOs indicated that the rapid prototyped AFOs performed comparably to the prefabricated polypropylene design. Conclusions The rapidly prototyped orthoses fabricated in this study provided good fit of the subject's anatomy compared to a prefabricated AFO while delivering comparable function (i.e. mechanical effect on the biomechanics of gait. The rapid fabrication capability is of interest because it has potential for decreasing fabrication time and cost especially when a replacement of the orthosis is required.

KEMAJUAN BELAJAR SISWA PADA GEOMETRI TRANSFORMASI MENGGUNAKAN AKTIVITAS REFLEKSI GEOMETRI

Directory of Open Access Journals (Sweden)

Irkham Ulil Albab

2014-10-01

Full Text Available Abstrak: Penelitian ini bertujuan untuk mendeskripsikan kemajuan belajar siswa pada materi geometri transformasi yang didukung dengan serangkaian aktivitas belajar berdasarkan Pendidikan Matematika Realistik Indonesia. Penelitian didesain melalui tiga tahap, yaitu tahapan perancangan desain awal, pengujian desain melalui pembelajaran awal dan pembelajaran eksperimental, dan tahap analisis retrospektif. Dalam penelitian ini, Hypothetical Learning Trajectory, HLT (HLT berperan penting sebagai desain pembelajaran sekaligus instrumen penelitian. HLT diujikan terhadap 26 siswa kelas VII. Data dikumpulkan dengan teknik wawancara, pengamatan, dan catatan lapangan. Hasil penelitian menunjukkan bahwa desain pembelajaran ini mampu menstimulasi siswa untuk memberikan karakteristik refleksi dan transformasi geometri lainnya secara informal, mengklasifikasikannya dalam transformasi isometri pada level kedua, dan menemukan garis bantuan refleksi pada level yang lebih formal. Selain itu, garis bantuan refleksi digunakan oleh siswa untuk menggambar bayangan refleksi dan pola pencerminan serta memahami bentuk rotasi dan translasi sebagai kombinasi refleksi adalah level tertinggi. Keyword: transformasi geometri, kombinasi refleksi, rotasi, translasi, design research, HLT STUDENTS’ LEARNING PROGRESS ON TRANSFORMATION GEOMETRY USING THE GEOMETRY REFLECTION ACTIVITIES Abstract: This study was aimed at describing the students’ learning progress on transformation geometry supported by a set of learning activities based on Indonesian Realistic Mathematics Education. The study was designed into three stages, that is, the preliminary design stage, the design testing through initial instruction and experiment, and the restrospective analysis stage. In this study, Hypothetical Learning Trajectory (HLT played an important role as an instructional design and a research instrument. HLT was tested to 26 seventh grade students. The data were collected through interviews

Software Geometry in Simulations

Science.gov (United States)

Alion, Tyler; Viren, Brett; Junk, Tom

2015-04-01

The Long Baseline Neutrino Experiment (LBNE) involves many detectors. The experiment's near detector (ND) facility, may ultimately involve several detectors. The far detector (FD) will be significantly larger than any other Liquid Argon (LAr) detector yet constructed; many prototype detectors are being constructed and studied to motivate a plethora of proposed FD designs. Whether it be a constructed prototype or a proposed ND/FD design, every design must be simulated and analyzed. This presents a considerable challenge to LBNE software experts; each detector geometry must be described to the simulation software in an efficient way which allows for multiple authors to easily collaborate. Furthermore, different geometry versions must be tracked throughout their use. We present a framework called General Geometry Description (GGD), written and developed by LBNE software collaborators for managing software to generate geometries. Though GGD is flexible enough to be used by any experiment working with detectors, we present it's first use in generating Geometry Description Markup Language (GDML) files to interface with LArSoft, a framework of detector simulations, event reconstruction, and data analyses written for all LAr technology users at Fermilab. Brett is the other of the framework discussed here, the General Geometry Description (GGD).

Methods of information geometry

CERN Document Server

Amari, Shun-Ichi

2000-01-01

Information geometry provides the mathematical sciences with a new framework of analysis. It has emerged from the investigation of the natural differential geometric structure on manifolds of probability distributions, which consists of a Riemannian metric defined by the Fisher information and a one-parameter family of affine connections called the \\alpha-connections. The duality between the \\alpha-connection and the (-\\alpha)-connection together with the metric play an essential role in this geometry. This kind of duality, having emerged from manifolds of probability distributions, is ubiquitous, appearing in a variety of problems which might have no explicit relation to probability theory. Through the duality, it is possible to analyze various fundamental problems in a unified perspective. The first half of this book is devoted to a comprehensive introduction to the mathematical foundation of information geometry, including preliminaries from differential geometry, the geometry of manifolds or probability d...

Developments in special geometry

International Nuclear Information System (INIS)

Mohaupt, Thomas; Vaughan, Owen

2012-01-01

We review the special geometry of N = 2 supersymmetric vector and hypermultiplets with emphasis on recent developments and applications. A new formulation of the local c-map based on the Hesse potential and special real coordinates is presented. Other recent developments include the Euclidean version of special geometry, and generalizations of special geometry to non-supersymmetric theories. As applications we discuss the proof that the local r-map and c-map preserve geodesic completeness, and the construction of four- and five-dimensional static solutions through dimensional reduction over time. The shared features of the real, complex and quaternionic version of special geometry are stressed throughout.

Planetary Image Geometry Library

Science.gov (United States)

Deen, Robert C.; Pariser, Oleg

2010-01-01

The Planetary Image Geometry (PIG) library is a multi-mission library used for projecting images (EDRs, or Experiment Data Records) and managing their geometry for in-situ missions. A collection of models describes cameras and their articulation, allowing application programs such as mosaickers, terrain generators, and pointing correction tools to be written in a multi-mission manner, without any knowledge of parameters specific to the supported missions. Camera model objects allow transformation of image coordinates to and from view vectors in XYZ space. Pointing models, specific to each mission, describe how to orient the camera models based on telemetry or other information. Surface models describe the surface in general terms. Coordinate system objects manage the various coordinate systems involved in most missions. File objects manage access to metadata (labels, including telemetry information) in the input EDRs and RDRs (Reduced Data Records). Label models manage metadata information in output files. Site objects keep track of different locations where the spacecraft might be at a given time. Radiometry models allow correction of radiometry for an image. Mission objects contain basic mission parameters. Pointing adjustment ("nav") files allow pointing to be corrected. The object-oriented structure (C++) makes it easy to subclass just the pieces of the library that are truly mission-specific. Typically, this involves just the pointing model and coordinate systems, and parts of the file model. Once the library was developed (initially for Mars Polar Lander, MPL), adding new missions ranged from two days to a few months, resulting in significant cost savings as compared to rewriting all the application programs for each mission. Currently supported missions include Mars Pathfinder (MPF), MPL, Mars Exploration Rover (MER), Phoenix, and Mars Science Lab (MSL). Applications based on this library create the majority of operational image RDRs for those missions. A

Age-specific mortality among TB patients in Denmark 1998-2010

DEFF Research Database (Denmark)

Fløe, Andreas; Løkke, Anders; Ibsen, Rikke

Objective: To evaluate the age-specific mortality in a national TB cohort, and to estimate relative age-specific mortality compared with matched controls, in a retrospective case-control study. Methods: Using Danish National Patient Registry, we retrospectively identified TB-patients between 1998...... to matched controls. While the difference in survival is substantial among elderly patients, a high relative risk of dying is particularly of concern among young and middle-aged adult TB patients....

Primary stability of a cementless acetabular cup in a cohort of patient-specific finite element models.

Science.gov (United States)

O'Rourke, Dermot; Al-Dirini, Rami Ma; Taylor, Mark

2018-03-01

The primary stability achieved during total hip arthroplasty determines the long-term success of cementless acetabular cups. Pre-clinical finite element testing of cups typically use a model of a single patient and assume the results can be extrapolated to the general population. This study explored the variability in predicted primary stability of a Pinnacle ® cementless acetabular cup in 103 patient-specific finite element models of the hemipelvis and examined the association between patient-related factors and the observed variability. Cups were inserted by displacement-control into the FE models and then a loading configuration simulating a complete level gait cycle was applied. The cohort showed a range of polar gap of 284-1112 μm and 95th percentile composite peak micromotion (CPM) of 18-624 μm. Regression analysis was not conclusive on the relationship between patient-related factors and primary stability. No relationship was found between polar gap and micromotion. However, when the patient-related factors were categorised into quartile groups, trends suggested higher polar gaps occurred in subjects with small and shallow acetabular geometries and cup motion during gait was affected most by low elastic modulus and high bodyweight. The variation in primary stability in the cohort for an acetabular cup with a proven clinical track record may provide benchmark data when evaluating new cup designs. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1012-1023, 2018. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Surgeon Design Interface for Patient-Specific Concentric Tube Robots.

Science.gov (United States)

Morimoto, Tania K; Greer, Joseph D; Hsieh, Michael H; Okamura, Allison M

2016-06-01

Concentric tube robots have potential for use in a wide variety of surgical procedures due to their small size, dexterity, and ability to move in highly curved paths. Unlike most existing clinical robots, the design of these robots can be developed and manufactured on a patient- and procedure-specific basis. The design of concentric tube robots typically requires significant computation and optimization, and it remains unclear how the surgeon should be involved. We propose to use a virtual reality-based design environment for surgeons to easily and intuitively visualize and design a set of concentric tube robots for a specific patient and procedure. In this paper, we describe a novel patient-specific design process in the context of the virtual reality interface. We also show a resulting concentric tube robot design, created by a pediatric urologist to access a kidney stone in a pediatric patient.

Impact of obesity on left ventricular geometry and function in pediatric patients after successful aortic coarctation repair.

Science.gov (United States)

Di Salvo, Giovanni; Gala, Simona; Castaldi, Biagio; Baldini, Luca; Limongelli, Giuseppe; D'Andrea, Antonello; Scognamiglio, Giancarlo; Sarubbi, Berardo; Caso, Pio; Pacileo, Giuseppe; Giovanna Russo, Maria; Calabrò, Raffaele

2011-09-01

To evaluate if obesity has an additional negative impact on left ventricular (LV) geometry and function in normotensive pediatric patients >12 months after successful treatment of aortic coarctation (CoA). We studied 40 CoA patients (mean age 14 ± 3 years, and male sex 70%), of them 10 were obese and 30 lean. Both groups were age and sex comparable. The entire studied sample underwent 24-ambulatory blood pressure (BP) monitoring, standard echocardiographic evaluation, and speckle tracking study. Both office and 24-hour diastolic BP were significantly increased in obese patients. Obese CoA patients showed increased LV mass (52 ± 13 g/m(2.7) vs. 43 ± 9 g/m(2.7) , P = 0.02), and significant reduction in E/A compared with lean CoA patients. Myocardial deformation properties were significantly reduced in obese CoA patients in all the three studied planes (longitudinal, radial, and circumferential) compared with CoA lean patients. LV twist values showed a significant reduction in the obese CoA group (9.9° ± 2.2° vs. 14.5° ± 2.3°, P < 0.0001). Our study shows that obesity in successfully treated CoA children, has an additional negative effect on BP, LV mass, and cardiac function. These findings are of particular concern, since life expectancy in CoA patients is limited mainly by atherosclerosis, and all the obesity-associated abnormalities found are harbingers of higher cardiovascular risk. © 2011, Wiley Periodicals, Inc.

The design of geometry teaching: learning from the geometry textbooks of Godfrey and Siddons

OpenAIRE

Fujita, Taro; Jones, Keith

2002-01-01

Deciding how to teach geometry remains a demanding task with one of major arguments being about how to combine the intuitive and deductive aspects of geometry into an effective teaching design. In order to try to obtain an insight into tackling this issue, this paper reports an analysis of innovative geometry textbooks which were published in the early part of the 20th Century, a time when significant efforts were being made to improve the teaching and learning of geometry. The analysis sugge...

Patient-Specific Surgical Implants Made of 3D Printed PEEK: Material, Technology, and Scope of Surgical Application

Directory of Open Access Journals (Sweden)

Philipp Honigmann

2018-01-01

Full Text Available Additive manufacturing (AM is rapidly gaining acceptance in the healthcare sector. Three-dimensional (3D virtual surgical planning, fabrication of anatomical models, and patient-specific implants (PSI are well-established processes in the surgical fields. Polyetheretherketone (PEEK has been used, mainly in the reconstructive surgeries as a reliable alternative to other alloplastic materials for the fabrication of PSI. Recently, it has become possible to fabricate PEEK PSI with Fused Filament Fabrication (FFF technology. 3D printing of PEEK using FFF allows construction of almost any complex design geometry, which cannot be manufactured using other technologies. In this study, we fabricated various PEEK PSI by FFF 3D printer in an effort to check the feasibility of manufacturing PEEK with 3D printing. Based on these preliminary results, PEEK can be successfully used as an appropriate biomaterial to reconstruct the surgical defects in a “biomimetic” design.

Patient-Specific Surgical Implants Made of 3D Printed PEEK: Material, Technology, and Scope of Surgical Application.

Science.gov (United States)

Honigmann, Philipp; Sharma, Neha; Okolo, Brando; Popp, Uwe; Msallem, Bilal; Thieringer, Florian M

2018-01-01

Additive manufacturing (AM) is rapidly gaining acceptance in the healthcare sector. Three-dimensional (3D) virtual surgical planning, fabrication of anatomical models, and patient-specific implants (PSI) are well-established processes in the surgical fields. Polyetheretherketone (PEEK) has been used, mainly in the reconstructive surgeries as a reliable alternative to other alloplastic materials for the fabrication of PSI. Recently, it has become possible to fabricate PEEK PSI with Fused Filament Fabrication (FFF) technology. 3D printing of PEEK using FFF allows construction of almost any complex design geometry, which cannot be manufactured using other technologies. In this study, we fabricated various PEEK PSI by FFF 3D printer in an effort to check the feasibility of manufacturing PEEK with 3D printing. Based on these preliminary results, PEEK can be successfully used as an appropriate biomaterial to reconstruct the surgical defects in a "biomimetic" design.

Sources of hyperbolic geometry

CERN Document Server

Stillwell, John

1996-01-01

This book presents, for the first time in English, the papers of Beltrami, Klein, and Poincaré that brought hyperbolic geometry into the mainstream of mathematics. A recognition of Beltrami comparable to that given the pioneering works of Bolyai and Lobachevsky seems long overdue-not only because Beltrami rescued hyperbolic geometry from oblivion by proving it to be logically consistent, but because he gave it a concrete meaning (a model) that made hyperbolic geometry part of ordinary mathematics. The models subsequently discovered by Klein and Poincaré brought hyperbolic geometry even further down to earth and paved the way for the current explosion of activity in low-dimensional geometry and topology. By placing the works of these three mathematicians side by side and providing commentaries, this book gives the student, historian, or professional geometer a bird's-eye view of one of the great episodes in mathematics. The unified setting and historical context reveal the insights of Beltrami, Klein, and Po...

Patient-specific radiation dose and cancer risk estimation in CT: Part II. Application to patients

Energy Technology Data Exchange (ETDEWEB)

Li Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Toncheva, Greta; Yoshizumi, Terry T.; Frush, Donald P. [Medical Physics Graduate Program, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Department of Physics, and Department of Biomedical Engineering, Duke University Medical Center, Durham, North Carolina 27705 (United States); Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705 (United States); Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599 (United States); Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Duke Radiation Dosimetry Laboratory, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Duke Radiation Dosimetry Laboratory, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705 (United States); Division of Pediatric Radiology, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27710 (United States)

2011-01-15

Purpose: Current methods for estimating and reporting radiation dose from CT examinations are largely patient-generic; the body size and hence dose variation from patient to patient is not reflected. Furthermore, the current protocol designs rely on dose as a surrogate for the risk of cancer incidence, neglecting the strong dependence of risk on age and gender. The purpose of this study was to develop a method for estimating patient-specific radiation dose and cancer risk from CT examinations. Methods: The study included two patients (a 5-week-old female patient and a 12-year-old male patient), who underwent 64-slice CT examinations (LightSpeed VCT, GE Healthcare) of the chest, abdomen, and pelvis at our institution in 2006. For each patient, a nonuniform rational B-spine (NURBS) based full-body computer model was created based on the patient's clinical CT data. Large organs and structures inside the image volume were individually segmented and modeled. Other organs were created by transforming an existing adult male or female full-body computer model (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. A Monte Carlo program previously developed and validated for dose simulation on the LightSpeed VCT scanner was used to estimate patient-specific organ dose, from which effective dose and risks of cancer incidence were derived. Patient-specific organ dose and effective dose were compared with patient-generic CT dose quantities in current clinical use: the volume-weighted CT dose index (CTDI{sub vol}) and the effective dose derived from the dose-length product (DLP). Results: The effective dose for the CT examination of the newborn patient (5.7 mSv) was higher but comparable to that for the CT examination of the teenager patient (4.9 mSv) due to the size-based clinical CT protocols at our institution, which employ lower scan techniques for smaller

The geometry description markup language

International Nuclear Information System (INIS)

Chytracek, R.

2001-01-01

Currently, a lot of effort is being put on designing complex detectors. A number of simulation and reconstruction frameworks and applications have been developed with the aim to make this job easier. A very important role in this activity is played by the geometry description of the detector apparatus layout and its working environment. However, no real common approach to represent geometry data is available and such data can be found in various forms starting from custom semi-structured text files, source code (C/C++/FORTRAN), to XML and database solutions. The XML (Extensible Markup Language) has proven to provide an interesting approach for describing detector geometries, with several different but incompatible XML-based solutions existing. Therefore, interoperability and geometry data exchange among different frameworks is not possible at present. The author introduces a markup language for geometry descriptions. Its aim is to define a common approach for sharing and exchanging of geometry description data. Its requirements and design have been driven by experience and user feedback from existing projects which have their geometry description in XML

Complex analysis and CR geometry

CERN Document Server

Zampieri, Giuseppe

2008-01-01

Cauchy-Riemann (CR) geometry is the study of manifolds equipped with a system of CR-type equations. Compared to the early days when the purpose of CR geometry was to supply tools for the analysis of the existence and regularity of solutions to the \\bar\\partial-Neumann problem, it has rapidly acquired a life of its own and has became an important topic in differential geometry and the study of non-linear partial differential equations. A full understanding of modern CR geometry requires knowledge of various topics such as real/complex differential and symplectic geometry, foliation theory, the geometric theory of PDE's, and microlocal analysis. Nowadays, the subject of CR geometry is very rich in results, and the amount of material required to reach competence is daunting to graduate students who wish to learn it. However, the present book does not aim at introducing all the topics of current interest in CR geometry. Instead, an attempt is made to be friendly to the novice by moving, in a fairly relaxed way, f...

ORIGAMI -- The Oak Ridge Geometry Analysis and Modeling Interface

International Nuclear Information System (INIS)

Burns, T.J.

1996-01-01

A revised ''ray-tracing'' package which is a superset of the geometry specifications of the radiation transport codes MORSE, MASH (GIFT Versions 4 and 5), HETC, and TORT has been developed by ORNL. Two additional CAD-based formats are also included as part of the superset: the native format of the BRL-CAD system--MGED, and the solid constructive geometry subset of the IGES specification. As part of this upgrade effort, ORNL has designed an Xwindows-based utility (ORIGAMI) to facilitate the construction, manipulation, and display of the geometric models required by the MASH code. Since the primary design criterion for this effort was that the utility ''see'' the geometric model exactly as the radiation transport code does, ORIGAMI is designed to utilize the same ''ray-tracing'' package as the revised version of MASH. ORIGAMI incorporates the functionality of two previously developed graphical utilities, CGVIEW and ORGBUG, into a single consistent interface

Global aspects of complex geometry

CERN Document Server

Catanese, Fabrizio; Huckleberry, Alan T

2006-01-01

Present an overview of developments in Complex Geometry. This book covers topics that range from curve and surface theory through special varieties in higher dimensions, moduli theory, Kahler geometry, and group actions to Hodge theory and characteristic p-geometry.

Aortic root geometry in aortic stenosis patients (a SEAS substudy)

DEFF Research Database (Denmark)

Bahlmann, Edda; Nienaber, Christoph A; Cramariuc, Dana

2011-01-01

-specified requirements for the aortic root geometry for current available prostheses, CoreValve and Edwards-Sapien. The ratio of sinus of Valsalva height to sinus width was 1:2. In multivariate linear regression analysis, larger sinus of Valsalva height was associated with older age, larger sinus of Valsalva diameter......, lower ejection fraction and smaller supracoronary diameter (multiple R(2) = 0.19, PSapien prosthesis in 66.9%. Overall, annular dimension feasible for TAVI using any available prosthesis was found...

Analytic geometry

CERN Document Server

Burdette, A C

1971-01-01

Analytic Geometry covers several fundamental aspects of analytic geometry needed for advanced subjects, including calculus.This book is composed of 12 chapters that review the principles, concepts, and analytic proofs of geometric theorems, families of lines, the normal equation of the line, and related matters. Other chapters highlight the application of graphing, foci, directrices, eccentricity, and conic-related topics. The remaining chapters deal with the concept polar and rectangular coordinates, surfaces and curves, and planes.This book will prove useful to undergraduate trigonometric st

Vector geometry

CERN Document Server

Robinson, Gilbert de B

2011-01-01

This brief undergraduate-level text by a prominent Cambridge-educated mathematician explores the relationship between algebra and geometry. An elementary course in plane geometry is the sole requirement for Gilbert de B. Robinson's text, which is the result of several years of teaching and learning the most effective methods from discussions with students. Topics include lines and planes, determinants and linear equations, matrices, groups and linear transformations, and vectors and vector spaces. Additional subjects range from conics and quadrics to homogeneous coordinates and projective geom

Physics- and engineering knowledge-based geometry repair system for robust parametric CAD geometries

OpenAIRE

Li, Dong

2012-01-01

In modern multi-objective design optimisation, an effective geometry engine is becoming an essential tool and its performance has a significant impact on the entire process. Building a parametric geometry requires difficult compromises between the conflicting goals of robustness and flexibility. The work presents a solution for improving the robustness of parametric geometry models by capturing and modelling relative engineering knowledge into a surrogate model, and deploying it automatically...

Noncommutative geometry

CERN Document Server

Connes, Alain

1994-01-01

This English version of the path-breaking French book on this subject gives the definitive treatment of the revolutionary approach to measure theory, geometry, and mathematical physics developed by Alain Connes. Profusely illustrated and invitingly written, this book is ideal for anyone who wants to know what noncommutative geometry is, what it can do, or how it can be used in various areas of mathematics, quantization, and elementary particles and fields.Key Features* First full treatment of the subject and its applications* Written by the pioneer of this field* Broad applications in mathemat

Geometry Revealed

CERN Document Server

Berger, Marcel

2010-01-01

Both classical geometry and modern differential geometry have been active subjects of research throughout the 20th century and lie at the heart of many recent advances in mathematics and physics. The underlying motivating concept for the present book is that it offers readers the elements of a modern geometric culture by means of a whole series of visually appealing unsolved (or recently solved) problems that require the creation of concepts and tools of varying abstraction. Starting with such natural, classical objects as lines, planes, circles, spheres, polygons, polyhedra, curves, surfaces,

Discrete differential geometry. Consistency as integrability

OpenAIRE

Bobenko, Alexander I.; Suris, Yuri B.

2005-01-01

A new field of discrete differential geometry is presently emerging on the border between differential and discrete geometry. Whereas classical differential geometry investigates smooth geometric shapes (such as surfaces), and discrete geometry studies geometric shapes with finite number of elements (such as polyhedra), the discrete differential geometry aims at the development of discrete equivalents of notions and methods of smooth surface theory. Current interest in this field derives not ...

Spinorial Geometry and Branes

International Nuclear Information System (INIS)

Sloane, Peter

2007-01-01

We adapt the spinorial geometry method introduced in [J. Gillard, U. Gran and G. Papadopoulos, 'The spinorial geometry of supersymmetric backgrounds,' Class. Quant. Grav. 22 (2005) 1033 [ (arXiv:hep-th/0410155)

Room acoustics modeling using a point-cloud representation of the room geometry

DEFF Research Database (Denmark)

Markovic, Milos; Olesen, Søren Krarup; Hammershøi, Dorte

2013-01-01

Room acoustics modeling is usually based on the room geometry that is parametrically described prior to a sound transmission calculation. This is a highly room-specific task and rather time consuming if a complex geometry is to be described. Here, a run time generic method for an arbitrary room...... geometry acquisition is presented. The method exploits a depth sensor of the Kinect device that provides a point based information of a scanned room interior. After post-processing of the Kinect output data, a 3D point-cloud model of the room is obtained. Sound transmission between two selected points...... level of user immersion by a real time acoustical simulation of a dynamic scenes....

Geometry effects on the (e, 2e) cross section on ionic targets

International Nuclear Information System (INIS)

Khajuria, Y.

2005-01-01

The three body distorted wave Born approximation (DWBA) with spin averaged static exchange potential has been used to calculate the electron impact triple-differential cross section of Li + , Na + and K + ions in different geometries and kinematics. In coplanar geometry at high incident energy (≥ 500 eV) and scattering angle ∼10deg, both recoil and binary peaks in case of p-orbital electrons splits into two. The value of the binary to the recoil peak ratio for the specific value of the momentum transfer has been determined to understand the collision dynamics. In the non-coplanar geometry a strong interference resulting in a dip in triple differential cross section (TDCS) has been noticed. (author)

An introduction to incidence geometry

CERN Document Server

De Bruyn, Bart

2016-01-01

This book gives an introduction to the field of Incidence Geometry by discussing the basic families of point-line geometries and introducing some of the mathematical techniques that are essential for their study. The families of geometries covered in this book include among others the generalized polygons, near polygons, polar spaces, dual polar spaces and designs. Also the various relationships between these geometries are investigated. Ovals and ovoids of projective spaces are studied and some applications to particular geometries will be given. A separate chapter introduces the necessary mathematical tools and techniques from graph theory. This chapter itself can be regarded as a self-contained introduction to strongly regular and distance-regular graphs. This book is essentially self-contained, only assuming the knowledge of basic notions from (linear) algebra and projective and affine geometry. Almost all theorems are accompanied with proofs and a list of exercises with full solutions is given at the end...

Interactive three-dimensional visualization and creation of geometries for Monte Carlo calculations

International Nuclear Information System (INIS)

Theis, C.; Buchegger, K.H.; Brugger, M.; Forkel-Wirth, D.; Roesler, S.; Vincke, H.

2006-01-01

The implementation of three-dimensional geometries for the simulation of radiation transport problems is a very time-consuming task. Each particle transport code supplies its own scripting language and syntax for creating the geometries. All of them are based on the Constructive Solid Geometry scheme requiring textual description. This makes the creation a tedious and error-prone task, which is especially hard to master for novice users. The Monte Carlo code FLUKA comes with built-in support for creating two-dimensional cross-sections through the geometry and FLUKACAD, a custom-built converter to the commercial Computer Aided Design package AutoCAD, exists for 3D visualization. For other codes, like MCNPX, a couple of different tools are available, but they are often specifically tailored to the particle transport code and its approach used for implementing geometries. Complex constructive solid modeling usually requires very fast and expensive special purpose hardware, which is not widely available. In this paper SimpleGeo is presented, which is an implementation of a generic versatile interactive geometry modeler using off-the-shelf hardware. It is running on Windows, with a Linux version currently under preparation. This paper describes its functionality, which allows for rapid interactive visualization as well as generation of three-dimensional geometries, and also discusses critical issues regarding common CAD systems

Patient-specific quality assurance for the delivery of (60)Co intensity modulated radiation therapy subject to a 0.35-T lateral magnetic field.

Science.gov (United States)

Li, H Harold; Rodriguez, Vivian L; Green, Olga L; Hu, Yanle; Kashani, Rojano; Wooten, H Omar; Yang, Deshan; Mutic, Sasa

2015-01-01

This work describes a patient-specific dosimetry quality assurance (QA) program for intensity modulated radiation therapy (IMRT) using ViewRay, the first commercial magnetic resonance imaging-guided RT device. The program consisted of: (1) a 1-dimensional multipoint ionization chamber measurement using a customized 15-cm(3) cube-shaped phantom; (2) 2-dimensional (2D) radiographic film measurement using a 30- × 30- × 20-cm(3) phantom with multiple inserted ionization chambers; (3) quasi-3D diode array (ArcCHECK) measurement with a centrally inserted ionization chamber; (4) 2D fluence verification using machine delivery log files; and (5) 3D Monte Carlo (MC) dose reconstruction with machine delivery files and phantom CT. Ionization chamber measurements agreed well with treatment planning system (TPS)-computed doses in all phantom geometries where the mean ± SD difference was 0.0% ± 1.3% (n=102; range, -3.0%-2.9%). Film measurements also showed excellent agreement with the TPS-computed 2D dose distributions where the mean passing rate using 3% relative/3 mm gamma criteria was 94.6% ± 3.4% (n=30; range, 87.4%-100%). For ArcCHECK measurements, the mean ± SD passing rate using 3% relative/3 mm gamma criteria was 98.9% ± 1.1% (n=34; range, 95.8%-100%). 2D fluence maps with a resolution of 1 × 1 mm(2) showed 100% passing rates for all plan deliveries (n=34). The MC reconstructed doses to the phantom agreed well with planned 3D doses where the mean passing rate using 3% absolute/3 mm gamma criteria was 99.0% ± 1.0% (n=18; range, 97.0%-100%), demonstrating the feasibility of evaluating the QA results in the patient geometry. We developed a dosimetry program for ViewRay's patient-specific IMRT QA. The methodology will be useful for other ViewRay users. The QA results presented here can assist the RT community to establish appropriate tolerance and action limits for ViewRay's IMRT QA. Copyright © 2015 Elsevier Inc. All rights reserved.

COGEDIF - automatic TORT and DORT input generation from MORSE combinatorial geometry models

International Nuclear Information System (INIS)

Castelli, R.A.; Barnett, D.A.

1992-01-01

COGEDIF is an interactive utility which was developed to automate the preparation of two and three dimensional geometrical inputs for the ORNL-TORT and DORT discrete ordinates programs from complex three dimensional models described using the MORSE combinatorial geometry input description. The program creates either continuous or disjoint mesh input based upon the intersections of user defined meshing planes and the MORSE body definitions. The composition overlay of the combinatorial geometry is used to create the composition mapping of the discretized geometry based upon the composition found at the centroid of each of the mesh cells. This program simplifies the process of using discrete orthogonal mesh cells to represent non-orthogonal geometries in large models which require mesh sizes of the order of a million cells or more. The program was specifically written to take advantage of the new TORT disjoint mesh option which was developed at ORNL

Spinorial Geometry and Branes

Energy Technology Data Exchange (ETDEWEB)

Sloane, Peter [Department of Mathematics, King' s College, University of London, Strand, London WC2R 2LS (United Kingdom)

2007-09-15

We adapt the spinorial geometry method introduced in [J. Gillard, U. Gran and G. Papadopoulos, 'The spinorial geometry of supersymmetric backgrounds,' Class. Quant. Grav. 22 (2005) 1033 [ (arXiv:hep-th/0410155)

Introduction to non-Euclidean geometry

CERN Document Server

Wolfe, Harold E

2012-01-01

One of the first college-level texts for elementary courses in non-Euclidean geometry, this concise, readable volume is geared toward students familiar with calculus. A full treatment of the historical background explores the centuries-long efforts to prove Euclid's parallel postulate and their triumphant conclusion. Numerous original exercises form an integral part of the book.Topics include hyperbolic plane geometry and hyperbolic plane trigonometry, applications of calculus to the solutions of some problems in hyperbolic geometry, elliptic plane geometry and trigonometry, and the consistenc

Optical geometry across the horizon

International Nuclear Information System (INIS)

Jonsson, Rickard

2006-01-01

In a recent paper (Jonsson and Westman 2006 Class. Quantum Grav. 23 61), a generalization of optical geometry, assuming a non-shearing reference congruence, is discussed. Here we illustrate that this formalism can be applied to (a finite four-volume) of any spherically symmetric spacetime. In particular we apply the formalism, using a non-static reference congruence, to do optical geometry across the horizon of a static black hole. While the resulting geometry in principle is time dependent, we can choose the reference congruence in such a manner that an embedding of the geometry always looks the same. Relative to the embedded geometry the reference points are then moving. We discuss the motion of photons, inertial forces and gyroscope precession in this framework

Dose distribution in organs: patient-specific phantoms versus reference phantoms

Energy Technology Data Exchange (ETDEWEB)

Lacerda, I.V.B., E-mail: isabelle.lacerda@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife (Brazil); Vieira, J.W. [Instituto Federal de Pernambuco (IFPE), Recife (Brazil); Oliveira, M.L.; Lima, F.R.A. [Centro Regional de Ciências Nucleares do Nordeste (CRCN-NE/CNEN-PB), Recife (Brazil)

2017-07-01

Discrepancies between ICRP phantoms and real patients lead to disparities on patient-dose estimations. This paper aims to compare distribution of dose in organs of male/female specific-phantoms and ICRP reference phantoms. The absorbed dose estimation was performed using the EGSnrc Monte Carlo code and a parallel source algorithm. In this work were used a patient-specific phantom for a man (1.73m/70.3kg) and another for a woman (1.63m/60.3kg) and the male and female ICRP reference phantoms. The comparison of the absorbed dose from each phantom gender was performed using the relative error. The results were expressed in terms of conversion coefficients to brain, lungs, liver and kidneys. The greatest absolute relative error between the organs of the patient-specific phantom and the reference phantom was 22.92% in the liver and 62.84% in the kidneys, respectively for man and woman. There are errors that cannot be disregarded. This paper shows the need for a specific study for each patient or for the population of each country, since there are different body types, which affects the distribution of the organ doses. (author)

Dose distribution in organs: patient-specific phantoms versus reference phantoms

International Nuclear Information System (INIS)

Lacerda, I.V.B.; Vieira, J.W.; Oliveira, M.L.; Lima, F.R.A.

2017-01-01

Discrepancies between ICRP phantoms and real patients lead to disparities on patient-dose estimations. This paper aims to compare distribution of dose in organs of male/female specific-phantoms and ICRP reference phantoms. The absorbed dose estimation was performed using the EGSnrc Monte Carlo code and a parallel source algorithm. In this work were used a patient-specific phantom for a man (1.73m/70.3kg) and another for a woman (1.63m/60.3kg) and the male and female ICRP reference phantoms. The comparison of the absorbed dose from each phantom gender was performed using the relative error. The results were expressed in terms of conversion coefficients to brain, lungs, liver and kidneys. The greatest absolute relative error between the organs of the patient-specific phantom and the reference phantom was 22.92% in the liver and 62.84% in the kidneys, respectively for man and woman. There are errors that cannot be disregarded. This paper shows the need for a specific study for each patient or for the population of each country, since there are different body types, which affects the distribution of the organ doses. (author)

A fluid-structure interaction study using patient-specific ruptured and unruptured aneurysm: the effect of aneurysm morphology, hypertension and elasticity.

Science.gov (United States)

Lee, C J; Zhang, Y; Takao, H; Murayama, Y; Qian, Y

2013-09-27

Fluid-structure interaction (FSI) simulations using five patient-specific aneurysm geometries are carried out to investigate the difference between ruptured and unruptured aneurysms. Two different blood pressure conditions (normal and hypertension, for all cases), and two different values of elastic modulus (1 and 2MPa, for two cases) are tested. Ruptured aneurysms (RA) generally displayed larger displacement at the dome, lower area-average WSS and higher von Mises stress than unruptured aneurysms (URA) regardless of elasticity or blood pressure condition. RAs had a longitudinal expansion whereas URAs had a radial expansion, which was the key difference between the two types. The difference in expansion pattern may be one of the keys to explaining aneurysm rupture, and further analysis is required in the future to confirm this theory. Copyright © 2013 Elsevier Ltd. All rights reserved.

Intelligent Patching of Conceptual Geometry for CFD Analysis

Science.gov (United States)

Li, Wu

2010-01-01

The iPatch computer code for intelligently patching surface grids was developed to convert conceptual geometry to computational fluid dynamics (CFD) geometry (see figure). It automatically uses bicubic B-splines to extrapolate (if necessary) each surface in a conceptual geometry so that all the independently defined geometric components (such as wing and fuselage) can be intersected to form a watertight CFD geometry. The software also computes the intersection curves of surface patches at any resolution (up to 10.4 accuracy) specified by the user, and it writes the B-spline surface patches, and the corresponding boundary points, for the watertight CFD geometry in the format that can be directly used by the grid generation tool VGRID. iPatch requires that input geometry be in PLOT3D format where each component surface is defined by a rectangular grid {(x(i,j), y(i,j), z(i,j)):1less than or equal to i less than or equal to m, 1 less than or equal to j less than or equal to n} that represents a smooth B-spline surface. All surfaces in the PLOT3D file conceptually represent a watertight geometry of components of an aircraft on the half-space y greater than or equal to 0. Overlapping surfaces are not allowed, but could be fixed by a utility code "fixp3d". The fixp3d utility code first finds the two grid lines on the two surface grids that are closest to each other in Hausdorff distance (a metric to measure the discrepancies of two sets); then uses one of the grid lines as the transition line, extending grid lines on one grid to the other grid to form a merged grid. Any two connecting surfaces shall have a "visually" common boundary curve, or can be described by an intersection relationship defined in a geometry specification file. The intersection of two surfaces can be at a conceptual level. However, the intersection is directional (along either i or j index direction), and each intersecting grid line (or its spine extrapolation) on the first surface should intersect

Moduli spaces in algebraic geometry

International Nuclear Information System (INIS)

Goettsche, L.

2000-01-01

This volume of the new series of lecture notes of the Abdus Salam International Centre for Theoretical Physics contains the lecture notes of the School on Algebraic Geometry which took place at the Abdus Salam International Centre for Theoretical Physics from 26 July to 13 August 1999. The school consisted of 2 weeks of lecture courses and one week of conference. The topic of the school was moduli spaces. More specifically the lectures were divided into three subtopics: principal bundles on Riemann surfaces, moduli spaces of vector bundles and sheaves on projective varieties, and moduli spaces of curves

SU-E-T-558: Monte Carlo Photon Transport Simulations On GPU with Quadric Geometry

International Nuclear Information System (INIS)

Chi, Y; Tian, Z; Jiang, S; Jia, X

2015-01-01

Purpose: Monte Carlo simulation on GPU has experienced rapid advancements over the past a few years and tremendous accelerations have been achieved. Yet existing packages were developed only in voxelized geometry. In some applications, e.g. radioactive seed modeling, simulations in more complicated geometry are needed. This abstract reports our initial efforts towards developing a quadric geometry module aiming at expanding the application scope of GPU-based MC simulations. Methods: We defined the simulation geometry consisting of a number of homogeneous bodies, each specified by its material composition and limiting surfaces characterized by quadric functions. A tree data structure was utilized to define geometric relationship between different bodies. We modified our GPU-based photon MC transport package to incorporate this geometry. Specifically, geometry parameters were loaded into GPU’s shared memory for fast access. Geometry functions were rewritten to enable the identification of the body that contains the current particle location via a fast searching algorithm based on the tree data structure. Results: We tested our package in an example problem of HDR-brachytherapy dose calculation for shielded cylinder. The dose under the quadric geometry and that under the voxelized geometry agreed in 94.2% of total voxels within 20% isodose line based on a statistical t-test (95% confidence level), where the reference dose was defined to be the one at 0.5cm away from the cylinder surface. It took 243sec to transport 100million source photons under this quadric geometry on an NVidia Titan GPU card. Compared with simulation time of 99.6sec in the voxelized geometry, including quadric geometry reduced efficiency due to the complicated geometry-related computations. Conclusion: Our GPU-based MC package has been extended to support photon transport simulation in quadric geometry. Satisfactory accuracy was observed with a reduced efficiency. Developments for charged

SU-E-T-558: Monte Carlo Photon Transport Simulations On GPU with Quadric Geometry

Energy Technology Data Exchange (ETDEWEB)

Chi, Y; Tian, Z; Jiang, S; Jia, X [The University of Texas Southwestern Medical Ctr, Dallas, TX (United States)

2015-06-15

Purpose: Monte Carlo simulation on GPU has experienced rapid advancements over the past a few years and tremendous accelerations have been achieved. Yet existing packages were developed only in voxelized geometry. In some applications, e.g. radioactive seed modeling, simulations in more complicated geometry are needed. This abstract reports our initial efforts towards developing a quadric geometry module aiming at expanding the application scope of GPU-based MC simulations. Methods: We defined the simulation geometry consisting of a number of homogeneous bodies, each specified by its material composition and limiting surfaces characterized by quadric functions. A tree data structure was utilized to define geometric relationship between different bodies. We modified our GPU-based photon MC transport package to incorporate this geometry. Specifically, geometry parameters were loaded into GPU’s shared memory for fast access. Geometry functions were rewritten to enable the identification of the body that contains the current particle location via a fast searching algorithm based on the tree data structure. Results: We tested our package in an example problem of HDR-brachytherapy dose calculation for shielded cylinder. The dose under the quadric geometry and that under the voxelized geometry agreed in 94.2% of total voxels within 20% isodose line based on a statistical t-test (95% confidence level), where the reference dose was defined to be the one at 0.5cm away from the cylinder surface. It took 243sec to transport 100million source photons under this quadric geometry on an NVidia Titan GPU card. Compared with simulation time of 99.6sec in the voxelized geometry, including quadric geometry reduced efficiency due to the complicated geometry-related computations. Conclusion: Our GPU-based MC package has been extended to support photon transport simulation in quadric geometry. Satisfactory accuracy was observed with a reduced efficiency. Developments for charged

Convection in Slab and Spheroidal Geometries

Science.gov (United States)

Porter, David H.; Woodward, Paul R.; Jacobs, Michael L.

2000-01-01

Three-dimensional numerical simulations of compressible turbulent thermally driven convection, in both slab and spheroidal geometries, are reviewed and analyzed in terms of velocity spectra and mixing-length theory. The same ideal gas model is used in both geometries, and resulting flows are compared. The piecewise-parabolic method (PPM), with either thermal conductivity or photospheric boundary conditions, is used to solve the fluid equations of motion. Fluid motions in both geometries exhibit a Kolmogorov-like k(sup -5/3) range in their velocity spectra. The longest wavelength modes are energetically dominant in both geometries, typically leading to one convection cell dominating the flow. In spheroidal geometry, a dipolar flow dominates the largest scale convective motions. Downflows are intensely turbulent and up drafts are relatively laminar in both geometries. In slab geometry, correlations between temperature and velocity fluctuations, which lead to the enthalpy flux, are fairly independent of depth. In spheroidal geometry this same correlation increases linearly with radius over the inner 70 percent by radius, in which the local pressure scale heights are a sizable fraction of the radius. The effects from the impenetrable boundary conditions in the slab geometry models are confused with the effects from non-local convection. In spheroidal geometry nonlocal effects, due to coherent plumes, are seen as far as several pressure scale heights from the lower boundary and are clearly distinguishable from boundary effects.

Complex and symplectic geometry

CERN Document Server

Medori, Costantino; Tomassini, Adriano

2017-01-01

This book arises from the INdAM Meeting "Complex and Symplectic Geometry", which was held in Cortona in June 2016. Several leading specialists, including young researchers, in the field of complex and symplectic geometry, present the state of the art of their research on topics such as the cohomology of complex manifolds; analytic techniques in Kähler and non-Kähler geometry; almost-complex and symplectic structures; special structures on complex manifolds; and deformations of complex objects. The work is intended for researchers in these areas.

Initiation to global Finslerian geometry

CERN Document Server

Akbar-Zadeh, Hassan

2006-01-01

After a brief description of the evolution of thinking on Finslerian geometry starting from Riemann, Finsler, Berwald and Elie Cartan, the book gives a clear and precise treatment of this geometry. The first three chapters develop the basic notions and methods, introduced by the author, to reach the global problems in Finslerian Geometry. The next five chapters are independent of each other, and deal with among others the geometry of generalized Einstein manifolds, the classification of Finslerian manifolds of constant sectional curvatures. They also give a treatment of isometric, affine, p

Algebraic geometry in India

Indian Academy of Sciences (India)

algebraic geometry but also in related fields like number theory. ... every vector bundle on the affine space is trivial. (equivalently ... les on a compact Riemann surface to unitary rep- ... tial geometry and topology and was generalised in.

Generalizing optical geometry

International Nuclear Information System (INIS)

Jonsson, Rickard; Westman, Hans

2006-01-01

We show that by employing the standard projected curvature as a measure of spatial curvature, we can make a certain generalization of optical geometry (Abramowicz M A and Lasota J-P 1997 Class. Quantum Grav. A 14 23-30). This generalization applies to any spacetime that admits a hypersurface orthogonal shearfree congruence of worldlines. This is a somewhat larger class of spacetimes than the conformally static spacetimes assumed in standard optical geometry. In the generalized optical geometry, which in the generic case is time dependent, photons move with unit speed along spatial geodesics and the sideways force experienced by a particle following a spatially straight line is independent of the velocity. Also gyroscopes moving along spatial geodesics do not precess (relative to the forward direction). Gyroscopes that follow a curved spatial trajectory precess according to a very simple law of three-rotation. We also present an inertial force formalism in coordinate representation for this generalization. Furthermore, we show that by employing a new sense of spatial curvature (Jonsson R 2006 Class. Quantum Grav. 23 1)) closely connected to Fermat's principle, we can make a more extensive generalization of optical geometry that applies to arbitrary spacetimes. In general this optical geometry will be time dependent, but still geodesic photons move with unit speed and follow lines that are spatially straight in the new sense. Also, the sideways experienced (comoving) force on a test particle following a line that is straight in the new sense will be independent of the velocity

Mucorales-Specific T Cells in Patients with Hematologic Malignancies

OpenAIRE

Potenza, L; Vallerini, D; Barozzi, P; Riva, G; Gilioli, A; Forghieri, F; Candoni, A; Cesaro, S; Quadrelli, C; Maertens, J; Rossi, G; Morselli, M; Codeluppi, M; Mussini, C; Colaci, E

2016-01-01

Background Invasive mucormycosis (IM) is an emerging life-threatening fungal infection. It is difficult to obtain a definite diagnosis and to initiate timely intervention. Mucorales-specific T cells occur during the course of IM and are involved in the clearance of the infection. We have evaluated the feasibility of detecting Mucorales-specific T cells in hematological patients at risk for IM, and have correlated the detection of such cells with the clinical conditions of the patients. Method...

Introduction to combinatorial geometry

International Nuclear Information System (INIS)

Gabriel, T.A.; Emmett, M.B.

1985-01-01

The combinatorial geometry package as used in many three-dimensional multimedia Monte Carlo radiation transport codes, such as HETC, MORSE, and EGS, is becoming the preferred way to describe simple and complicated systems. Just about any system can be modeled using the package with relatively few input statements. This can be contrasted against the older style geometry packages in which the required input statements could be large even for relatively simple systems. However, with advancements come some difficulties. The users of combinatorial geometry must be able to visualize more, and, in some instances, all of the system at a time. Errors can be introduced into the modeling which, though slight, and at times hard to detect, can have devastating effects on the calculated results. As with all modeling packages, the best way to learn the combinatorial geometry is to use it, first on a simple system then on more complicated systems. The basic technique for the description of the geometry consists of defining the location and shape of the various zones in terms of the intersections and unions of geometric bodies. The geometric bodies which are generally included in most combinatorial geometry packages are: (1) box, (2) right parallelepiped, (3) sphere, (4) right circular cylinder, (5) right elliptic cylinder, (6) ellipsoid, (7) truncated right cone, (8) right angle wedge, and (9) arbitrary polyhedron. The data necessary to describe each of these bodies are given. As can be easily noted, there are some subsets included for simplicity

Sieve Tube Geometry in Relation to Phloem Flow

Science.gov (United States)

Mullendore, Daniel L.; Windt, Carel W.; Van As, Henk; Knoblauch, Michael

2010-01-01

Sieve elements are one of the least understood cell types in plants. Translocation velocities and volume flow to supply sinks with photoassimilates greatly depend on the geometry of the microfluidic sieve tube system and especially on the anatomy of sieve plates and sieve plate pores. Several models for phloem translocation have been developed, but appropriate data on the geometry of pores, plates, sieve elements, and flow parameters are lacking. We developed a method to clear cells from cytoplasmic constituents to image cell walls by scanning electron microscopy. This method allows high-resolution measurements of sieve element and sieve plate geometries. Sieve tube–specific conductivity and its reduction by callose deposition after injury was calculated for green bean (Phaseolus vulgaris), bamboo (Phyllostachys nuda), squash (Cucurbita maxima), castor bean (Ricinus communis), and tomato (Solanum lycopersicum). Phloem sap velocity measurements by magnetic resonance imaging velocimetry indicate that higher conductivity is not accompanied by a higher velocity. Studies on the temporal development of callose show that small sieve plate pores might be occluded by callose within minutes, but plants containing sieve tubes with large pores need additional mechanisms. PMID:20354199

Graded geometry and Poisson reduction

OpenAIRE

Cattaneo, A S; Zambon, M

2009-01-01

The main result of [2] extends the Marsden-Ratiu reduction theorem [4] in Poisson geometry, and is proven by means of graded geometry. In this note we provide the background material about graded geometry necessary for the proof in [2]. Further, we provide an alternative algebraic proof for the main result. ©2009 American Institute of Physics

Geometry of multihadron production

Energy Technology Data Exchange (ETDEWEB)

Bjorken, J.D.

1994-10-01

This summary talk only reviews a small sample of topics featured at this symposium: Introduction; The Geometry and Geography of Phase space; Space-Time Geometry and HBT; Multiplicities, Intermittency, Correlations; Disoriented Chiral Condensate; Deep Inelastic Scattering at HERA; and Other Contributions.

Geometry of multihadron production

International Nuclear Information System (INIS)

Bjorken, J.D.

1994-10-01

This summary talk only reviews a small sample of topics featured at this symposium: Introduction; The Geometry and Geography of Phase space; Space-Time Geometry and HBT; Multiplicities, Intermittency, Correlations; Disoriented Chiral Condensate; Deep Inelastic Scattering at HERA; and Other Contributions

Geometry of higher-dimensional black hole thermodynamics

International Nuclear Information System (INIS)

Aaman, Jan E.; Pidokrajt, Narit

2006-01-01

We investigate thermodynamic curvatures of the Kerr and Reissner-Nordstroem (RN) black holes in spacetime dimensions higher than four. These black holes possess thermodynamic geometries similar to those in four-dimensional spacetime. The thermodynamic geometries are the Ruppeiner geometry and the conformally related Weinhold geometry. The Ruppeiner geometry for a d=5 Kerr black hole is curved and divergent in the extremal limit. For a d≥6 Kerr black hole there is no extremality but the Ruppeiner curvature diverges where one suspects that the black hole becomes unstable. The Weinhold geometry of the Kerr black hole in arbitrary dimension is a flat geometry. For the RN black hole the Ruppeiner geometry is flat in all spacetime dimensions, whereas its Weinhold geometry is curved. In d≥5 the Kerr black hole can possess more than one angular momentum. Finally we discuss the Ruppeiner geometry for the Kerr black hole in d=5 with double angular momenta

Study of geometries of active magnetic regenerators for room temperature magnetocaloric refrigeration

DEFF Research Database (Denmark)

Lei, Tian; Engelbrecht, Kurt; Nielsen, Kaspar Kirstein

2017-01-01

Room temperature magnetic refrigeration has attracted substantial attention during the past decades and continuing to increase the performance of active magnetic regenerators (AMR) is of great interest. Optimizing the regenerator geometry and related operating parameters is a practical and effect......Room temperature magnetic refrigeration has attracted substantial attention during the past decades and continuing to increase the performance of active magnetic regenerators (AMR) is of great interest. Optimizing the regenerator geometry and related operating parameters is a practical...... and effective way to obtain the desired cooling performance. To investigate how to choose and optimize the AMR geometry, a quantitative study is presented by simulations based on a one-dimensional (1D) numerical model. Correlations for calculating the friction factor and heat transfer coefficient are reviewed...... and chosen for modeling different geometries. Moreover, the simulated impacts of various parameters on the regenerator efficiency with a constant specific cooling capacity are presented. An analysis based on entropy production minimization reveals how those parameters affect the main losses occurring inside...

Methodology for wind turbine blade geometry optimization

Energy Technology Data Exchange (ETDEWEB)

Perfiliev, D.

2013-11-01

Nowadays, the upwind three bladed horizontal axis wind turbine is the leading player on the market. It has been found to be the best industrial compromise in the range of different turbine constructions. The current wind industry innovation is conducted in the development of individual turbine components. The blade constitutes 20-25% of the overall turbine budget. Its optimal operation in particular local economic and wind conditions is worth investigating. The blade geometry, namely the chord, twist and airfoil type distributions along the span, responds to the output measures of the blade performance. Therefore, the optimal wind blade geometry can improve the overall turbine performance. The objectives of the dissertation are focused on the development of a methodology and specific tool for the investigation of possible existing wind blade geometry adjustments. The novelty of the methodology presented in the thesis is the multiobjective perspective on wind blade geometry optimization, particularly taking simultaneously into account the local wind conditions and the issue of aerodynamic noise emissions. The presented optimization objective approach has not been investigated previously for the implementation in wind blade design. The possibilities to use different theories for the analysis and search procedures are investigated and sufficient arguments derived for the usage of proposed theories. The tool is used for the test optimization of a particular wind turbine blade. The sensitivity analysis shows the dependence of the outputs on the provided inputs, as well as its relative and absolute divergences and instabilities. The pros and cons of the proposed technique are seen from the practical implementation, which is documented in the results, analysis and conclusion sections. (orig.)

Reference geometry-based detection of (4D-)CT motion artifacts: a feasibility study

Science.gov (United States)

Werner, René; Gauer, Tobias

2015-03-01

Respiration-correlated computed tomography (4D or 3D+t CT) can be considered as standard of care in radiation therapy treatment planning for lung and liver lesions. The decision about an application of motion management devices and the estimation of patient-specific motion effects on the dose distribution relies on precise motion assessment in the planning 4D CT data { which is impeded in case of CT motion artifacts. The development of image-based/post-processing approaches to reduce motion artifacts would benefit from precise detection and localization of the artifacts. Simple slice-by-slice comparison of intensity values and threshold-based analysis of related metrics suffer from- depending on the threshold- high false-positive or -negative rates. In this work, we propose exploiting prior knowledge about `ideal' (= artifact free) reference geometries to stabilize metric-based artifact detection by transferring (multi-)atlas-based concepts to this specific task. Two variants are introduced and evaluated: (S1) analysis and comparison of warped atlas data obtained by repeated non-linear atlas-to-patient registration with different levels of regularization; (S2) direct analysis of vector field properties (divergence, curl magnitude) of the atlas-to-patient transformation. Feasibility of approaches (S1) and (S2) is evaluated by motion-phantom data and intra-subject experiments (four patients) as well as - adopting a multi-atlas strategy- inter-subject investigations (twelve patients involved). It is demonstrated that especially sorting/double structure artifacts can be precisely detected and localized by (S1). In contrast, (S2) suffers from high false positive rates.

Patient Specific Modeling of Head-Up Tilt

DEFF Research Database (Denmark)

Williams, Nakeya; Wright, Andrew; Mehlsen, Jesper

2014-01-01

Short term cardiovascular responses to head-up tilt (HUT) experiments involve complex cardiovascular regulation in order to maintain blood pressure at homeostatic levels. This manuscript presents a patient specific compartmental model developed to predict dynamic changes in heart rate and arterial...

Lectures on Symplectic Geometry

CERN Document Server

Silva, Ana Cannas

2001-01-01

The goal of these notes is to provide a fast introduction to symplectic geometry for graduate students with some knowledge of differential geometry, de Rham theory and classical Lie groups. This text addresses symplectomorphisms, local forms, contact manifolds, compatible almost complex structures, Kaehler manifolds, hamiltonian mechanics, moment maps, symplectic reduction and symplectic toric manifolds. It contains guided problems, called homework, designed to complement the exposition or extend the reader's understanding. There are by now excellent references on symplectic geometry, a subset of which is in the bibliography of this book. However, the most efficient introduction to a subject is often a short elementary treatment, and these notes attempt to serve that purpose. This text provides a taste of areas of current research and will prepare the reader to explore recent papers and extensive books on symplectic geometry where the pace is much faster. For this reprint numerous corrections and cl...

New frontier in regenerative medicine: site-specific gene correction in patient-specific induced pluripotent stem cells.

Science.gov (United States)

Garate, Zita; Davis, Brian R; Quintana-Bustamante, Oscar; Segovia, Jose C

2013-06-01

Advances in cell and gene therapy are opening up new avenues for regenerative medicine. Because of their acquired pluripotency, human induced pluripotent stem cells (hiPSCs) are a promising source of autologous cells for regenerative medicine. They show unlimited self-renewal while retaining the ability, in principle, to differentiate into any cell type of the human body. Since Yamanaka and colleagues first reported the generation of hiPSCs in 2007, significant efforts have been made to understand the reprogramming process and to generate hiPSCs with potential for clinical use. On the other hand, the development of gene-editing platforms to increase homologous recombination efficiency, namely DNA nucleases (zinc finger nucleases, TAL effector nucleases, and meganucleases), is making the application of locus-specific gene therapy in human cells an achievable goal. The generation of patient-specific hiPSC, together with gene correction by homologous recombination, will potentially allow for their clinical application in the near future. In fact, reports have shown targeted gene correction through DNA-Nucleases in patient-specific hiPSCs. Various technologies have been described to reprogram patient cells and to correct these patient hiPSCs. However, no approach has been clearly more efficient and safer than the others. In addition, there are still significant challenges for the clinical application of these technologies, such as inefficient differentiation protocols, genetic instability resulting from the reprogramming process and hiPSC culture itself, the efficacy and specificity of the engineered DNA nucleases, and the overall homologous recombination efficiency. To summarize advances in the generation of gene corrected patient-specific hiPSCs, this review focuses on the available technological platforms, including their strengths and limitations regarding future therapeutic use of gene-corrected hiPSCs.

Variations of intracavitary applicator geometry during multiple HDR brachytherapy insertions in carcinoma cervix and its influence on reporting as per ICRU report 38

International Nuclear Information System (INIS)

Datta, Niloy Ranjan; Kumar, Shaleen; Das, Koilpillai Joseph Maria; Pandey, Chandra Mani; Halder, Shikha; Ayyagari, Sunder

2001-01-01

Purpose: This paper examines the extent of variation in the applicator geometry during multiple high dose rate (HDR) intracavitary brachytherapy (ICBT) applications and its impact on reporting as per ICRU report 38. Materials and methods: Eighty orthogonal radiographs from 20 consecutive patients of carcinoma cervix (FIGO stages, IIA-IIIB) having four HDR ICBT applications of 6 Gy each at weekly intervals following teletherapy were evaluated. The applicator consisted of a flexible intrauterine tandem (IUT) independent of the ovoid assembly. The applicator geometry was evaluated in terms of: α angle, β angle, intrauterine length (IUTL), interovoid (IOV), os to right ovoid (ORT) and os to left ovoid (OLT) distances along with vertical (VDL) and anteroposterior displacements (ADL) of the os with respect to the ovoids. The Cartesian co-ordinates (X, Y, and Z) of the IUT tip, centre of both ovoids and os were also measured. Doses to right point A (ARD), left point A (ALD), along with a reference volume of 6 Gy for ICRU height (IRH), width (IRW), thickness (IRT) and volume (IRV) were estimated for each application. Results: Highly significant differences (P<0.001) between four insertions in any given patient across 20 patients for α angle, β angle, IUTL, IOV, ORT, VDL, co-ordinates of the IUT, ovoids and os were observed, except for ADL (P=0.041) and OLT (P=0.247). As a consequence, variations were observed in ARD (P=0.027), ALD (P=0.017); IRH, IRW, IRT and IRV (all P<0.001). Applicator factors which influenced the various dose specification parameters were: β angle and ORT for both ARD and ALD; UTLN, VDL and ORT for IRH; UTLN and IOV for IRW; UTLN for IRT and VDL for the 6 Gy IRV. Conclusions: A significant variation of the applicator geometry and its movement was observed in patients undergoing multiple HDR ICBT. This could have implications for reporting dose and volume specifications as required by ICRU report 38

Complex differential geometry

CERN Document Server

Zheng, Fangyang

2002-01-01

The theory of complex manifolds overlaps with several branches of mathematics, including differential geometry, algebraic geometry, several complex variables, global analysis, topology, algebraic number theory, and mathematical physics. Complex manifolds provide a rich class of geometric objects, for example the (common) zero locus of any generic set of complex polynomials is always a complex manifold. Yet complex manifolds behave differently than generic smooth manifolds; they are more coherent and fragile. The rich yet restrictive character of complex manifolds makes them a special and interesting object of study. This book is a self-contained graduate textbook that discusses the differential geometric aspects of complex manifolds. The first part contains standard materials from general topology, differentiable manifolds, and basic Riemannian geometry. The second part discusses complex manifolds and analytic varieties, sheaves and holomorphic vector bundles, and gives a brief account of the surface classifi...

Computational synthetic geometry

CERN Document Server

Bokowski, Jürgen

1989-01-01

Computational synthetic geometry deals with methods for realizing abstract geometric objects in concrete vector spaces. This research monograph considers a large class of problems from convexity and discrete geometry including constructing convex polytopes from simplicial complexes, vector geometries from incidence structures and hyperplane arrangements from oriented matroids. It turns out that algorithms for these constructions exist if and only if arbitrary polynomial equations are decidable with respect to the underlying field. Besides such complexity theorems a variety of symbolic algorithms are discussed, and the methods are applied to obtain new mathematical results on convex polytopes, projective configurations and the combinatorics of Grassmann varieties. Finally algebraic varieties characterizing matroids and oriented matroids are introduced providing a new basis for applying computer algebra methods in this field. The necessary background knowledge is reviewed briefly. The text is accessible to stud...

Designs and finite geometries

CERN Document Server

1996-01-01

Designs and Finite Geometries brings together in one place important contributions and up-to-date research results in this important area of mathematics. Designs and Finite Geometries serves as an excellent reference, providing insight into some of the most important research issues in the field.

Modeling retinal degeneration using patient-specific induced pluripotent stem cells.

Directory of Open Access Journals (Sweden)

Zi-Bing Jin

Full Text Available Retinitis pigmentosa (RP is the most common inherited human eye disease resulting in night blindness and visual defects. It is well known that the disease is caused by rod photoreceptor degeneration; however, it remains incurable, due to the unavailability of disease-specific human photoreceptor cells for use in mechanistic studies and drug screening. We obtained fibroblast cells from five RP patients with distinct mutations in the RP1, RP9, PRPH2 or RHO gene, and generated patient-specific induced pluripotent stem (iPS cells by ectopic expression of four key reprogramming factors. We differentiated the iPS cells into rod photoreceptor cells, which had been lost in the patients, and found that they exhibited suitable immunocytochemical features and electrophysiological properties. Interestingly, the number of the patient-derived rod cells with distinct mutations decreased in vitro; cells derived from patients with a specific mutation expressed markers for oxidation or endoplasmic reticulum stress, and exhibited different responses to vitamin E than had been observed in clinical trials. Overall, patient-derived rod cells recapitulated the disease phenotype and expressed markers of cellular stresses. Our results demonstrate that the use of patient-derived iPS cells will help to elucidate the pathogenic mechanisms caused by genetic mutations in RP.

Ambient Occlusion Effects for Combined Volumes and Tubular Geometry

KAUST Repository

Schott, M.; Martin, T.; Grosset, A. V. P.; Smith, S. T.; Hansen, C. D.

2013-01-01

This paper details a method for interactive direct volume rendering that computes ambient occlusion effects for visualizations that combine both volumetric and geometric primitives, specifically tube-shaped geometric objects representing streamlines, magnetic field lines or DTI fiber tracts. The algorithm extends the recently presented the directional occlusion shading model to allow the rendering of those geometric shapes in combination with a context providing 3D volume, considering mutual occlusion between structures represented by a volume or geometry. Stream tube geometries are computed using an effective spline-based interpolation and approximation scheme that avoids self-intersection and maintains coherent orientation of the stream tube segments to avoid surface deforming twists. Furthermore, strategies to reduce the geometric and specular aliasing of the stream tubes are discussed.

Ambient Occlusion Effects for Combined Volumes and Tubular Geometry

KAUST Repository

Schott, M.

2013-06-01

This paper details a method for interactive direct volume rendering that computes ambient occlusion effects for visualizations that combine both volumetric and geometric primitives, specifically tube-shaped geometric objects representing streamlines, magnetic field lines or DTI fiber tracts. The algorithm extends the recently presented the directional occlusion shading model to allow the rendering of those geometric shapes in combination with a context providing 3D volume, considering mutual occlusion between structures represented by a volume or geometry. Stream tube geometries are computed using an effective spline-based interpolation and approximation scheme that avoids self-intersection and maintains coherent orientation of the stream tube segments to avoid surface deforming twists. Furthermore, strategies to reduce the geometric and specular aliasing of the stream tubes are discussed.

Improvement in minimum detectable activity for low energy gamma by optimization in counting geometry

Directory of Open Access Journals (Sweden)

Anil Gupta

2017-01-01

Full Text Available Gamma spectrometry for environmental samples of low specific activities demands low minimum detection levels of measurement. An attempt has been made to lower the gamma detection level of measurement by optimizing the sample geometry, without compromising on the sample size. Gamma energy of 50–200 keV range was chosen for the study, since low energy gamma photons suffer the most self-attenuation within matrix. The simulation study was carried out using MCNP based software “EffCalcMC” for silica matrix and cylindrical geometries. A volume of 250 ml sample geometry of 9 cm diameter is optimized as the best suitable geometry for use, against the in-practice 7 cm diameter geometry of same volume. An increase in efficiency of 10%–23% was observed for the 50–200 keV gamma energy range and a corresponding lower minimum detectable activity of 9%–20% could be achieved for the same.

d-geometries revisited

CERN Document Server

Ceresole, Anna; Gnecchi, Alessandra; Marrani, Alessio

2013-01-01

We analyze some properties of the four dimensional supergravity theories which originate from five dimensions upon reduction. They generalize to N>2 extended supersymmetries the d-geometries with cubic prepotentials, familiar from N=2 special K\\"ahler geometry. We emphasize the role of a suitable parametrization of the scalar fields and the corresponding triangular symplectic basis. We also consider applications to the first order flow equations for non-BPS extremal black holes.

LEARNING GEOMETRY THROUGH MIMESIS AND DIGITAL CONSTRUCT

OpenAIRE

Maria Mion POP; Mihaela GIURGIULESCU

2015-01-01

The theme proposed by us is useful to teachers and students for mathematics in the compulsory school cycle. The issues faced by school teachers/parents are the difficulty with which students read and understand the lessons/examples/synthesis in order to assimilate technical terms. The echoic and iconic memory facilitates the learning of the specific curriculum of linear, spatial and analytical geometry by the students using digital platform designed by us; it facilitates the acquiring of the ...

Geometry success in 20 minutes a day

CERN Document Server

LLC, LearningExpress

2014-01-01

Whether you're new to geometry or just looking for a refresher, Geometry Success in 20 Minutes a Day offers a 20-step lesson plan that provides quick and thorough instruction in practical, critical skills. Stripped of unnecessary math jargon but bursting with geometry essentials, Geometry Success in 20 Minutes a Day: Covers all vital geometry skills, from the basic building blocks of geometry to ratio, proportion, and similarity to trigonometry and beyond Provides hundreds of practice exercises in test format Applies geometr

Lectures on coarse geometry

CERN Document Server

Roe, John

2003-01-01

Coarse geometry is the study of spaces (particularly metric spaces) from a 'large scale' point of view, so that two spaces that look the same from a great distance are actually equivalent. This point of view is effective because it is often true that the relevant geometric properties of metric spaces are determined by their coarse geometry. Two examples of important uses of coarse geometry are Gromov's beautiful notion of a hyperbolic group and Mostow's proof of his famous rigidity theorem. The first few chapters of the book provide a general perspective on coarse structures. Even when only metric coarse structures are in view, the abstract framework brings the same simplification as does the passage from epsilons and deltas to open sets when speaking of continuity. The middle section reviews notions of negative curvature and rigidity. Modern interest in large scale geometry derives in large part from Mostow's rigidity theorem and from Gromov's subsequent 'large scale' rendition of the crucial properties of n...

Introduction to tropical geometry

CERN Document Server

Maclagan, Diane

2015-01-01

Tropical geometry is a combinatorial shadow of algebraic geometry, offering new polyhedral tools to compute invariants of algebraic varieties. It is based on tropical algebra, where the sum of two numbers is their minimum and the product is their sum. This turns polynomials into piecewise-linear functions, and their zero sets into polyhedral complexes. These tropical varieties retain a surprising amount of information about their classical counterparts. Tropical geometry is a young subject that has undergone a rapid development since the beginning of the 21st century. While establishing itself as an area in its own right, deep connections have been made to many branches of pure and applied mathematics. This book offers a self-contained introduction to tropical geometry, suitable as a course text for beginning graduate students. Proofs are provided for the main results, such as the Fundamental Theorem and the Structure Theorem. Numerous examples and explicit computations illustrate the main concepts. Each of t...

Geometry Euclid and beyond

CERN Document Server

Hartshorne, Robin

2000-01-01

In recent years, I have been teaching a junior-senior-level course on the classi­ cal geometries. This book has grown out of that teaching experience. I assume only high-school geometry and some abstract algebra. The course begins in Chapter 1 with a critical examination of Euclid's Elements. Students are expected to read concurrently Books I-IV of Euclid's text, which must be obtained sepa­ rately. The remainder of the book is an exploration of questions that arise natu­ rally from this reading, together with their modern answers. To shore up the foundations we use Hilbert's axioms. The Cartesian plane over a field provides an analytic model of the theory, and conversely, we see that one can introduce coordinates into an abstract geometry. The theory of area is analyzed by cutting figures into triangles. The algebra of field extensions provides a method for deciding which geometrical constructions are possible. The investigation of the parallel postulate leads to the various non-Euclidean geometries. And ...

Morphing patient-specific musculoskeletal models

DEFF Research Database (Denmark)

Rasmussen, John; Galibarov, Pavel E.; Al-Munajjed, Amir

the resulting models do indeed represent the patients’ biomechanics. As a particularly challenging case, foot deformities based only on point sets recovered from surface scans are considered as shown in the figure. The preliminary results are promising for the cases of severe flat foot and metatarsalgia while...... other conditions may require CT or MRI data. The method and its theoretical assumptions, advantages and limitations are presented, and several examples will illustrate morphing to patient-specific models. [1] Carbes S; Tørholm S; Rasmussen, J. A Detailed Twenty-six Segments Kinematic Foot model...

Tropical geometry of statistical models.

Science.gov (United States)

Pachter, Lior; Sturmfels, Bernd

2004-11-16

This article presents a unified mathematical framework for inference in graphical models, building on the observation that graphical models are algebraic varieties. From this geometric viewpoint, observations generated from a model are coordinates of a point in the variety, and the sum-product algorithm is an efficient tool for evaluating specific coordinates. Here, we address the question of how the solutions to various inference problems depend on the model parameters. The proposed answer is expressed in terms of tropical algebraic geometry. The Newton polytope of a statistical model plays a key role. Our results are applied to the hidden Markov model and the general Markov model on a binary tree.

Prostate Cancer–Specific Mortality After Radical Prostatectomy for Patients Treated in the Prostate-Specific Antigen Era

Science.gov (United States)

Stephenson, Andrew J.; Kattan, Michael W.; Eastham, James A.; Bianco, Fernando J.; Yossepowitch, Ofer; Vickers, Andrew J.; Klein, Eric A.; Wood, David P.; Scardino, Peter T.

2009-01-01

Purpose The long-term risk of prostate cancer–specific mortality (PCSM) after radical prostatectomy is poorly defined for patients treated in the era of widespread prostate-specific antigen (PSA) screening. Models that predict the risk of PCSM are needed for patient counseling and clinical trial design. Methods A multi-institutional cohort of 12,677 patients treated with radical prostatectomy between 1987 and 2005 was analyzed for the risk of PCSM. Patient clinical information and treatment outcome was modeled using Fine and Gray competing risk regression analysis to predict PCSM. Results Fifteen-year PCSM and all-cause mortality were 12% and 38%, respectively. The estimated PCSM ranged from 5% to 38% for patients in the lowest and highest quartiles of predicted risk of PSA-defined recurrence, based on a popular nomogram. Biopsy Gleason grade, PSA, and year of surgery were associated with PCSM. A nomogram predicting the 15-year risk of PCSM was developed, and the externally validated concordance index was 0.82. Neither preoperative PSA velocity nor body mass index improved the model's accuracy. Only 4% of contemporary patients had a predicted 15-year PCSM of greater than 5%. Conclusion Few patients will die from prostate cancer within 15 years of radical prostatectomy, despite the presence of adverse clinical features. This favorable prognosis may be related to the effectiveness of radical prostatectomy (with or without secondary therapy) or the low lethality of screen-detected cancers. Given the limited ability to identify contemporary patients at substantially elevated risk of PCSM on the basis of clinical features alone, the need for novel markers specifically associated with the biology of lethal prostate cancer is evident. PMID:19636023

Basic algebraic geometry, v.2

CERN Document Server

Shafarevich, Igor Rostislavovich

1994-01-01

Shafarevich Basic Algebraic Geometry 2 The second edition of Shafarevich's introduction to algebraic geometry is in two volumes. The second volume covers schemes and complex manifolds, generalisations in two different directions of the affine and projective varieties that form the material of the first volume. Two notable additions in this second edition are the section on moduli spaces and representable functors, motivated by a discussion of the Hilbert scheme, and the section on Kähler geometry. The book ends with a historical sketch discussing the origins of algebraic geometry. From the Zentralblatt review of this volume: "... one can only respectfully repeat what has been said about the first part of the book (...): a great textbook, written by one of the leading algebraic geometers and teachers himself, has been reworked and updated. As a result the author's standard textbook on algebraic geometry has become even more important and valuable. Students, teachers, and active researchers using methods of al...

Canonical differential geometry of string backgrounds

International Nuclear Information System (INIS)

Schuller, Frederic P.; Wohlfarth, Mattias N.R.

2006-01-01

String backgrounds and D-branes do not possess the structure of Lorentzian manifolds, but that of manifolds with area metric. Area metric geometry is a true generalization of metric geometry, which in particular may accommodate a B-field. While an area metric does not determine a connection, we identify the appropriate differential geometric structure which is of relevance for the minimal surface equation in such a generalized geometry. In particular the notion of a derivative action of areas on areas emerges naturally. Area metric geometry provides new tools in differential geometry, which promise to play a role in the description of gravitational dynamics on D-branes

Gender-specific contribution of cardiometabolic index and lipid accumulation product to left ventricular geometry change in general population of rural China.

Science.gov (United States)

Wang, Haoyu; Sun, Yingxian; Li, Zhao; Guo, Xiaofan; Chen, Shuang; Ye, Ning; Tian, Yichen; Zhang, Lijun

2018-04-10

Despite current interest in the unfavorable impact of cardiometabolic index (CMI) and lipid accumulation product (LAP) on diabetes and cardiovascular risk, information regarding the relation of CMI and LAP to left ventricular (LV) geometry has not been specifically addressed. We aimed to examine the hypothesis: (1) CMI and LAP represent an independent determinant of LV remodeling in general population of rural China; (2) there are gender differences in obesity-related alterations in terms of LV morphology. The sample for this cross-sectional analysis included 11,258 participants (mean age 53.9 years; 54.0% females) who underwent assessment of basic metabolic and anthropometric parameters in rural areas of northeast China. Comprehensive echocardiography-defined LV geometric pattern was determined according to left ventricular mass index and relative wall thickness. The prevalence rate of eccentric and concentric LV hypertrophy (LVH) presented a proportional increase with elevated quartiles of CMI and LAP in a dose-response manner (all P factor of 3.552 and 1.768 in females and males, respectively. In contrast to females, where LAP fourth quartile and concentric LVH were positively associated (OR:2.544, 95%CI:1.537-4.209), higher LAP did not correlate with concentric LVH in males (OR:1.234, 95%CI:0.824-1.849). CMI and LAP give rise to a new paradigm of accounting for gender difference in obesity-related abnormal LV geometry, an effect that was substantially greater in females. These two indices, acting in concert, may also be advantageous prognostically for refining cardiovascular risk stratification in individuals with LV remodeling.

SU-F-BRE-08: Feasibility of 3D Printed Patient Specific Phantoms for IMRT/IGRT QA

International Nuclear Information System (INIS)

Ehler, E; Higgins, P; Dusenbery, K

2014-01-01

Purpose: Test the feasibility of 3D printed, per-patient phantoms for IMRT QA to analyze the treatment delivery quality within the patient geometry. Methods: Using the head and neck region of an anthropomorphic phantom as a substitute for an actual patient, a soft-tissue equivalent model was constructed with the use of a 3D printer. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom. During the delivery of the IMRT QA on to the 3D printed phantom, the same patient positioning indexing system was used on the phantom and image guidance (cone beam CT) was used to localize the phantom, serving as a test of the IGRT system as well. The 3D printed phantom was designed to accommodate four radiochromic film planes (two axial, one coronal and one sagittal) and an ionization chamber measurement. As a frame of comparison, the IMRT QA was also performed on traditional phantoms. Dosimetric tolerance levels such as 3mm / 3% Gamma Index as well as 3% and 5% dose difference were considered. All detector systems were calibrated against a NIST traceable ionization chamber. Results: Comparison of results 3D printed patient phantom with the standard IMRT QA systems showed similar passing rates for the 3D printed phantom and the standard phantoms. However, the locations of the failing regions did not necessarily correlate. The 3D printed phantom was localized within 1 mm and 1° using on-board cone beam CT. Conclusion: A custom phantom was created using a 3D printer. It was determined that the use of patient specific phantoms to perform dosimetric verification and estimate the dose in the patient is feasible. In addition, end-to-end testing on a per-patient basis was possible with the 3D printed phantom. Further refinement of the phantom construction process is needed for routine clinical use

SU-F-BRE-08: Feasibility of 3D Printed Patient Specific Phantoms for IMRT/IGRT QA

Energy Technology Data Exchange (ETDEWEB)

Ehler, E; Higgins, P; Dusenbery, K [University of Minnesota, Minneapolis, MN (United States)

2014-06-15

Purpose: Test the feasibility of 3D printed, per-patient phantoms for IMRT QA to analyze the treatment delivery quality within the patient geometry. Methods: Using the head and neck region of an anthropomorphic phantom as a substitute for an actual patient, a soft-tissue equivalent model was constructed with the use of a 3D printer. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom. During the delivery of the IMRT QA on to the 3D printed phantom, the same patient positioning indexing system was used on the phantom and image guidance (cone beam CT) was used to localize the phantom, serving as a test of the IGRT system as well. The 3D printed phantom was designed to accommodate four radiochromic film planes (two axial, one coronal and one sagittal) and an ionization chamber measurement. As a frame of comparison, the IMRT QA was also performed on traditional phantoms. Dosimetric tolerance levels such as 3mm / 3% Gamma Index as well as 3% and 5% dose difference were considered. All detector systems were calibrated against a NIST traceable ionization chamber. Results: Comparison of results 3D printed patient phantom with the standard IMRT QA systems showed similar passing rates for the 3D printed phantom and the standard phantoms. However, the locations of the failing regions did not necessarily correlate. The 3D printed phantom was localized within 1 mm and 1° using on-board cone beam CT. Conclusion: A custom phantom was created using a 3D printer. It was determined that the use of patient specific phantoms to perform dosimetric verification and estimate the dose in the patient is feasible. In addition, end-to-end testing on a per-patient basis was possible with the 3D printed phantom. Further refinement of the phantom construction process is needed for routine clinical use.

The analytic nodal method in cylindrical geometry

International Nuclear Information System (INIS)

Prinsloo, Rian H.; Tomasevic, Djordje I.

2008-01-01

Nodal diffusion methods have been used extensively in nuclear reactor calculations, specifically for their performance advantage, but also for their superior accuracy. More specifically, the Analytic Nodal Method (ANM), utilising the transverse integration principle, has been applied to numerous reactor problems with much success. In this work, a nodal diffusion method is developed for cylindrical geometry. Application of this method to three-dimensional (3D) cylindrical geometry has never been satisfactorily addressed and we propose a solution which entails the use of conformal mapping. A set of 1D-equations with an adjusted, geometrically dependent, inhomogeneous source, is obtained. This work describes the development of the method and associated test code, as well as its application to realistic reactor problems. Numerical results are given for the PBMR-400 MW benchmark problem, as well as for a 'cylindrisized' version of the well-known 3D LWR IAEA benchmark. Results highlight the improved accuracy and performance over finite-difference core solutions and investigate the applicability of nodal methods to 3D PBMR type problems. Results indicate that cylindrical nodal methods definitely have a place within PBMR applications, yielding performance advantage factors of 10 and 20 for 2D and 3D calculations, respectively, and advantage factors of the order of 1000 in the case of the LWR problem

Calculating patient specific doses in X-ray diagnostics and from radiopharmaceuticals

International Nuclear Information System (INIS)

Lampinen, J.

2000-01-01

The risk associated with exposure to ionising radiation is dependent on the characteristics of the exposed individual. The size and structure of the individual influences the absorbed dose distribution in the organs. Traditional methods used to calculate the patient organ doses are based on standardised calculation phantoms, which neglect the variance of the patient size or even sex. When estimating the radiation dose of an individual patient, patient specific calculation methods must be used. Methods for patient specific dosimetry in the fields of X-ray diagnostics and diagnostic and therapeutic use of radiopharmaceuticals were proposed in this thesis. A computer program, ODS-60, for calculating organ doses from diagnostic X-ray exposures was presented. The calculation is done in a patient specific phantom with depth dose and profile algorithms fitted to Monte Carlo simulation data from a previous study. Improvements to the version reported earlier were introduced, e.g. bone attenuation was implemented. The applicability of the program to determine patient doses from complex X-ray examinations (barium enema examination) was studied. The conversion equations derived for female and male patients as a function of patient weight gave the smallest deviation from the actual patient doses when compared to previous studies. Another computer program, Intdose, was presented for calculation of the dose distribution from radiopharmaceuticals. The calculation is based on convolution of an isotope specific point dose kernel with activity distribution, obtained from single photon emission computed tomography (SPECT) images. Anatomical information is taken from magnetic resonance (MR) or computed tomography (CT) images. According to a phantom study, Intdose agreed within 3 % with measurements. For volunteers administered diagnostic radiopharmaceuticals, the results given by Intdose were found to agree with traditional methods in cases of medium sized patients. For patients

The Beauty of Geometry

Science.gov (United States)

Morris, Barbara H.

2004-01-01

This article describes a geometry project that used the beauty of stained-glass-window designs to teach middle school students about geometric figures and concepts. Three honors prealgebra teachers and a middle school mathematics gifted intervention specialist created a geometry project that covered the curriculum and also assessed students'…

Teaching Spatial Geometry in a Virtual World

DEFF Research Database (Denmark)

Förster, Klaus-Tycho

2017-01-01

Spatial geometry is one of the fundamental mathematical building blocks of any engineering education. However, it is overshadowed by planar geometry in the curriculum between playful early primary education and later analytical geometry, leaving a multi-year gap where spatial geometry is absent...

Trends and developments in computational geometry

NARCIS (Netherlands)

Berg, de M.

1997-01-01

This paper discusses some trends and achievements in computational geometry during the past five years, with emphasis on problems related to computer graphics. Furthermore, a direction of research in computational geometry is discussed that could help in bringing the fields of computational geometry

Srna - Monte Carlo codes for proton transport simulation in combined and voxelized geometries

Directory of Open Access Journals (Sweden)

Ilić Radovan D.

2002-01-01

Full Text Available This paper describes new Monte Carlo codes for proton transport simulations in complex geometrical forms and in materials of different composition. The SRNA codes were developed for three dimensional (3D dose distribution calculation in proton therapy and dosimetry. The model of these codes is based on the theory of proton multiple scattering and a simple model of compound nucleus decay. The developed package consists of two codes: SRNA-2KG and SRNA-VOX. The first code simulates proton transport in combined geometry that can be described by planes and second order surfaces. The second one uses the voxelized geometry of material zones and is specifically adopted for the application of patient computer tomography data. Transition probabilities for both codes are given by the SRNADAT program. In this paper, we will present the models and algorithms of our programs, as well as the results of the numerical experiments we have carried out applying them, along with the results of proton transport simulation obtained through the PETRA and GEANT programs. The simulation of the proton beam characterization by means of the Multi-Layer Faraday Cup and spatial distribution of positron emitters obtained by our program indicate the imminent application of Monte Carlo techniques in clinical practice.

Patient-specific cardiac phantom for clinical training and preprocedure surgical planning.

Science.gov (United States)

Laing, Justin; Moore, John; Vassallo, Reid; Bainbridge, Daniel; Drangova, Maria; Peters, Terry

2018-04-01

Minimally invasive mitral valve repair procedures including MitraClip ® are becoming increasingly common. For cases of complex or diseased anatomy, clinicians may benefit from using a patient-specific cardiac phantom for training, surgical planning, and the validation of devices or techniques. An imaging compatible cardiac phantom was developed to simulate a MitraClip ® procedure. The phantom contained a patient-specific cardiac model manufactured using tissue mimicking materials. To evaluate accuracy, the patient-specific model was imaged using computed tomography (CT), segmented, and the resulting point cloud dataset was compared using absolute distance to the original patient data. The result, when comparing the molded model point cloud to the original dataset, resulted in a maximum Euclidean distance error of 7.7 mm, an average error of 0.98 mm, and a standard deviation of 0.91 mm. The phantom was validated using a MitraClip ® device to ensure anatomical features and tools are identifiable under image guidance. Patient-specific cardiac phantoms may allow for surgical complications to be accounted for preoperative planning. The information gained by clinicians involved in planning and performing the procedure should lead to shorter procedural times and better outcomes for patients.

Cell-geometry-dependent changes in plasma membrane order direct stem cell signalling and fate

Science.gov (United States)

von Erlach, Thomas C.; Bertazzo, Sergio; Wozniak, Michele A.; Horejs, Christine-Maria; Maynard, Stephanie A.; Attwood, Simon; Robinson, Benjamin K.; Autefage, Hélène; Kallepitis, Charalambos; del Río Hernández, Armando; Chen, Christopher S.; Goldoni, Silvia; Stevens, Molly M.

2018-03-01

Cell size and shape affect cellular processes such as cell survival, growth and differentiation1-4, thus establishing cell geometry as a fundamental regulator of cell physiology. The contributions of the cytoskeleton, specifically actomyosin tension, to these effects have been described, but the exact biophysical mechanisms that translate changes in cell geometry to changes in cell behaviour remain mostly unresolved. Using a variety of innovative materials techniques, we demonstrate that the nanostructure and lipid assembly within the cell plasma membrane are regulated by cell geometry in a ligand-independent manner. These biophysical changes trigger signalling events involving the serine/threonine kinase Akt/protein kinase B (PKB) that direct cell-geometry-dependent mesenchymal stem cell differentiation. Our study defines a central regulatory role by plasma membrane ordered lipid raft microdomains in modulating stem cell differentiation with potential translational applications.

An approach for management of geometry data

Science.gov (United States)

Dube, R. P.; Herron, G. J.; Schweitzer, J. E.; Warkentine, E. R.

1980-01-01

The strategies for managing Integrated Programs for Aerospace Design (IPAD) computer-based geometry are described. The computer model of geometry is the basis for communication, manipulation, and analysis of shape information. IPAD's data base system makes this information available to all authorized departments in a company. A discussion of the data structures and algorithms required to support geometry in IPIP (IPAD's data base management system) is presented. Through the use of IPIP's data definition language, the structure of the geometry components is defined. The data manipulation language is the vehicle by which a user defines an instance of the geometry. The manipulation language also allows a user to edit, query, and manage the geometry. The selection of canonical forms is a very important part of the IPAD geometry. IPAD has a canonical form for each entity and provides transformations to alternate forms; in particular, IPAD will provide a transformation to the ANSI standard. The DBMS schemas required to support IPAD geometry are explained.

MONTE CARLO ANALYSES OF THE YALINA THERMAL FACILITY WITH SERPENT STEREOLITHOGRAPHY GEOMETRY MODEL

Energy Technology Data Exchange (ETDEWEB)

Talamo, A.; Gohar, Y.

2015-01-01

This paper analyzes the YALINA Thermal subcritical assembly of Belarus using two different Monte Carlo transport programs, SERPENT and MCNP. The MCNP model is based on combinatorial geometry and universes hierarchy, while the SERPENT model is based on Stereolithography geometry. The latter consists of unstructured triangulated surfaces defined by the normal and vertices. This geometry format is used by 3D printers and it has been created by: the CUBIT software, MATLAB scripts, and C coding. All the Monte Carlo simulations have been performed using the ENDF/B-VII.0 nuclear data library. Both MCNP and SERPENT share the same geometry specifications, which describe the facility details without using any material homogenization. Three different configurations have been studied with different number of fuel rods. The three fuel configurations use 216, 245, or 280 fuel rods, respectively. The numerical simulations show that the agreement between SERPENT and MCNP results is within few tens of pcms.

3D modeling and visualization software for complex geometries

International Nuclear Information System (INIS)

Guse, Guenter; Klotzbuecher, Michael; Mohr, Friedrich

2011-01-01

The reactor safety depends on reliable nondestructive testing of reactor components. For 100% detection probability of flaws and the determination of their size using ultrasonic methods the ultrasonic waves have to hit the flaws within a specific incidence and squint angle. For complex test geometries like testing of nozzle welds from the outside of the component these angular ranges can only be determined using elaborate mathematical calculations. The authors developed a 3D modeling and visualization software tool that allows to integrate and present ultrasonic measuring data into the 3D geometry. The software package was verified using 1:1 test samples (example: testing of the nozzle edge of the feedwater nozzle of a steam generator from the outside; testing of the reactor pressure vessel nozzle edge from the inside).

"WGL," a Web Laboratory for Geometry

Science.gov (United States)

Quaresma, Pedro; Santos, Vanda; Maric, Milena

2018-01-01

The role of information and communication technologies (ICT) in education is nowadays well recognised. The "Web Geometry Laboratory," is an e-learning, collaborative and adaptive, Web environment for geometry, integrating a well known dynamic geometry system. In a collaborative session, teachers and students, engaged in solving…

Optimizing the Entrainment Geometry of a Dry Powder Inhaler: Methodology and Preliminary Results.

Science.gov (United States)

Kopsch, Thomas; Murnane, Darragh; Symons, Digby

2016-11-01

For passive dry powder inhalers (DPIs) entrainment and emission of the aerosolized drug dose depends strongly on device geometry and the patient's inhalation manoeuvre. We propose a computational method for optimizing the entrainment part of a DPI. The approach assumes that the pulmonary delivery location of aerosol can be determined by the timing of dose emission into the tidal airstream. An optimization algorithm was used to iteratively perform computational fluid dynamic (CFD) simulations of the drug emission of a DPI. The algorithm seeks to improve performance by changing the device geometry. Objectives were to achieve drug emission that was: A) independent of inhalation manoeuvre; B) similar to a target profile. The simulations used complete inhalation flow-rate profiles generated dependent on the device resistance. The CFD solver was OpenFOAM with drug/air flow simulated by the Eulerian-Eulerian method. To demonstrate the method, a 2D geometry was optimized for inhalation independence (comparing two breath profiles) and an early-bolus delivery. Entrainment was both shear-driven and gas-assisted. Optimization for a delay in the bolus delivery was not possible with the chosen geometry. Computational optimization of a DPI geometry for most similar drug delivery has been accomplished for an example entrainment geometry.

Analytische Geometrie

Science.gov (United States)

Kemnitz, Arnfried

Der Grundgedanke der Analytischen Geometrie besteht darin, dass geometrische Untersuchungen mit rechnerischen Mitteln geführt werden. Geometrische Objekte werden dabei durch Gleichungen beschrieben und mit algebraischen Methoden untersucht.

Connections between algebra, combinatorics, and geometry

CERN Document Server

Sather-Wagstaff, Sean

2014-01-01

Commutative algebra, combinatorics, and algebraic geometry are thriving areas of mathematical research with a rich history of interaction. Connections Between Algebra, Combinatorics, and Geometry contains lecture notes, along with exercises and solutions, from the Workshop on Connections Between Algebra and Geometry held at the University of Regina from May 29-June 1, 2012. It also contains research and survey papers from academics invited to participate in the companion Special Session on Interactions Between Algebraic Geometry and Commutative Algebra, which was part of the CMS Summer Meeting at the University of Regina held June 2–3, 2012, and the meeting Further Connections Between Algebra and Geometry, which was held at the North Dakota State University, February 23, 2013. This volume highlights three mini-courses in the areas of commutative algebra and algebraic geometry: differential graded commutative algebra, secant varieties, and fat points and symbolic powers. It will serve as a useful resou...

A Novel Geometry for Shear Test Using Axial Tensile Setup

Directory of Open Access Journals (Sweden)

Sibo Yuan

2018-05-01

Full Text Available This paper studies a novel geometry for the in-plane shear test performed with an axial electromechanical testing machine. In order to investigate the influence of the triaxiality rate on the mechanical behavior, different tests will be performed on the studied material: simple tensile tests, large tensile tests and shear tests. For the whole campaign, a common equipment should be employed to minimize the impact of the testing device. As a consequence, for the shear tests, the geometry of the specimen must be carefully designed in order to adapt the force value and make it comparable to the one obtained for the tensile tests. Like most of the existing shear-included tensile test specimens, the axial loading is converted to shear loading at a particular region through the effect of geometry. A symmetric shape is generally preferred, since it can restrict the in-plane rotation of the shear section, keep shear increasing in a more monotonic path and double the force level thanks to the two shear zones. Due to the specific experimental conditions, such as dimensions of the furnace and the clamping system, the position of the extensometer or the restriction of sheet thickness (related to the further studies of size effect at mesoscale and hot temperature, several geometries were brought up and evaluated in an iterative procedure via finite element simulations. Both the numerical and experimental results reveal that the final geometry ensures some advantages. For instance, a relatively low triaxiality in the shear zone, limited in-plane rotation and no necking are observed. Moreover, it also prevents any out-of-plane displacement of the specimen which seems to be highly sensitive to the geometry, and presents a very limited influence of the material and the thickness.

Managing patients with acute and chronic non-specific neck pain

DEFF Research Database (Denmark)

Brockhusen, Simon Sidenius; Bussières, André; French, Simon David

2017-01-01

was mainly reserved for chronic patients. Danish chiropractors' compliance with guidelines for neck-pain patients was low, but is neither worse nor better than what is seen for other complaints or health disciplines. Our findings suggest a need for active knowledge translation strategies and robust......Background: Non-specific neck pain represents a quarter of all chiropractic patient visits in Denmark. Evidence informed practice can help ensure providers use best available treatment, speed up patient recovery rate and reduce healthcare utilization. It is generally believed that Danish...... chiropractors treat according to best practice, but we do not know if this is true for management of neck-pain. The objective of this study was to investigate how Danish chiropractors treat patients with acute and chronic non-specific neck pain and determine if management is compliant with recent Canadian...

Cause-specific mortality in HPV+ and HPV- oropharyngeal cancer patients

DEFF Research Database (Denmark)

Nørregaard, Cecilie; Grønhøj, Christian; Jensen, David

2018-01-01

Identifying the causes of death in head and neck cancer patients can optimize follow-up and therapeutic strategies, but studies in oropharyngeal squamous cell carcinoma (OPSCC) patients stratified by HPV status are lacking. We report cause-specific mortality in a population-based cohort of patients...... with OPSCC. Patients who had been diagnosed with OPSCC (n = 1541) between 2000 and 2014 in eastern Denmark were included in the study. Causes of death were collected through medical files and the Danish National Cause of Death registry. Deaths were grouped as (1) primary oropharyngeal cancer, (2) secondary...... malignancies, (3) cardiovascular and pulmonary disease, or (4) other/unspecified. The cumulative incidence of death and specific causes of death were determined using risk analysis. At follow-up, 723 (47.5%) patients had died. The median time to and cause of death were determined: oropharyngeal cancer (n = 432...

3D-printed gelatin scaffolds of differing pore geometry modulate hepatocyte function and gene expression.

Science.gov (United States)

Lewis, Phillip L; Green, Richard M; Shah, Ramille N

2018-03-15

Three dimensional (3D) printing is highly amenable to the fabrication of tissue-engineered organs of a repetitive microstructure such as the liver. The creation of uniform and geometrically repetitive tissue scaffolds can also allow for the control over cellular aggregation and nutrient diffusion. However, the effect of differing geometries, while controlling for pore size, has yet to be investigated in the context of hepatocyte function. In this study, we show the ability to precisely control pore geometry of 3D-printed gelatin scaffolds. An undifferentiated hepatocyte cell line (HUH7) demonstrated high viability and proliferation when seeded on 3D-printed scaffolds of two different geometries. However, hepatocyte specific functions (albumin secretion, CYP activity, and bile transport) increases in more interconnected 3D-printed gelatin cultures compared to a less interconnected geometry and to 2D controls. Additionally, we also illustrate the disparity between gene expression and protein function in simple 2D culture modes, and that recreation of a physiologically mimetic 3D environment is necessary to induce both expression and function of cultured hepatocytes. Three dimensional (3D) printing provides tissue engineers the ability spatially pattern cells and materials in precise geometries, however the biological effects of scaffold geometry on soft tissues such as the liver have not been rigorously investigated. In this manuscript, we describe a method to 3D print gelatin into well-defined repetitive geometries that show clear differences in biological effects on seeded hepatocytes. We show that a relatively simple and widely used biomaterial, such as gelatin, can significantly modulate biological processes when fabricated into specific 3D geometries. Furthermore, this study expands upon past research into hepatocyte aggregation by demonstrating how it can be manipulated to enhance protein function, and how function and expression may not precisely correlate in

Algebraic Geometry and Number Theory Summer School

CERN Document Server

Sarıoğlu, Celal; Soulé, Christophe; Zeytin, Ayberk

2017-01-01

This lecture notes volume presents significant contributions from the “Algebraic Geometry and Number Theory” Summer School, held at Galatasaray University, Istanbul, June 2-13, 2014. It addresses subjects ranging from Arakelov geometry and Iwasawa theory to classical projective geometry, birational geometry and equivariant cohomology. Its main aim is to introduce these contemporary research topics to graduate students who plan to specialize in the area of algebraic geometry and/or number theory. All contributions combine main concepts and techniques with motivating examples and illustrative problems for the covered subjects. Naturally, the book will also be of interest to researchers working in algebraic geometry, number theory and related fields.

Applications of Affine and Weyl geometry

CERN Document Server

García-Río, Eduardo; Nikcevic, Stana

2013-01-01

Pseudo-Riemannian geometry is, to a large extent, the study of the Levi-Civita connection, which is the unique torsion-free connection compatible with the metric structure. There are, however, other affine connections which arise in different contexts, such as conformal geometry, contact structures, Weyl structures, and almost Hermitian geometry. In this book, we reverse this point of view and instead associate an auxiliary pseudo-Riemannian structure of neutral signature to certain affine connections and use this correspondence to study both geometries. We examine Walker structures, Riemannia

Fluid-Structure Simulations of a Ruptured Intracranial Aneurysm: Constant versus Patient-Specific Wall Thickness

Directory of Open Access Journals (Sweden)

S. Voß

2016-01-01

Full Text Available Computational Fluid Dynamics is intensively used to deepen the understanding of aneurysm growth and rupture in order to support physicians during therapy planning. However, numerous studies considering only the hemodynamics within the vessel lumen found no satisfactory criteria for rupture risk assessment. To improve available simulation models, the rigid vessel wall assumption has been discarded in this work and patient-specific wall thickness is considered within the simulation. For this purpose, a ruptured intracranial aneurysm was prepared ex vivo, followed by the acquisition of local wall thickness using μCT. The segmented inner and outer vessel surfaces served as solid domain for the fluid-structure interaction (FSI simulation. To compare wall stress distributions within the aneurysm wall and at the rupture site, FSI computations are repeated in a virtual model using a constant wall thickness approach. Although the wall stresses obtained by the two approaches—when averaged over the complete aneurysm sac—are in very good agreement, strong differences occur in their distribution. Accounting for the real wall thickness distribution, the rupture site exhibits much higher stress values compared to the configuration with constant wall thickness. The study reveals the importance of geometry reconstruction and accurate description of wall thickness in FSI simulations.

The Idea of Order at Geometry Class.

Science.gov (United States)

Rishel, Thomas

The idea of order in geometry is explored using the experience of assignments given to undergraduates in a college geometry course "From Space to Geometry." Discussed are the definition of geometry, and earth measurement using architecture, art, and common experience. This discussion concludes with a consideration of the question of whether…

Special geometry

International Nuclear Information System (INIS)

Strominger, A.

1990-01-01

A special manifold is an allowed target manifold for the vector multiplets of D=4, N=2 supergravity. These manifolds are of interest for string theory because the moduli spaces of Calabi-Yau threefolds and c=9, (2,2) conformal field theories are special. Previous work has given a local, coordinate-dependent characterization of special geometry. A global description of special geometries is given herein, and their properties are studied. A special manifold M of complex dimension n is characterized by the existence of a holomorphic Sp(2n+2,R)xGL(1,C) vector bundle over M with a nowhere-vanishing holomorphic section Ω. The Kaehler potential on M is the logarithm of the Sp(2n+2,R) invariant norm of Ω. (orig.)

Patient- and cohort-specific dose and risk estimation for abdominopelvic CT: a study based on 100 patients

Science.gov (United States)

Tian, Xiaoyu; Li, Xiang; Segars, W. Paul; Frush, Donald P.; Samei, Ehsan

2012-03-01

The purpose of this work was twofold: (a) to estimate patient- and cohort-specific radiation dose and cancer risk index for abdominopelvic computer tomography (CT) scans; (b) to evaluate the effects of patient anatomical characteristics (size, age, and gender) and CT scanner model on dose and risk conversion coefficients. The study included 100 patient models (42 pediatric models, 58 adult models) and multi-detector array CT scanners from two commercial manufacturers (LightSpeed VCT, GE Healthcare; SOMATOM Definition Flash, Siemens Healthcare). A previously-validated Monte Carlo program was used to simulate organ dose for each patient model and each scanner, from which DLP-normalized-effective dose (k factor) and DLP-normalized-risk index values (q factor) were derived. The k factor showed exponential decrease with increasing patient size. For a given gender, q factor showed exponential decrease with both increasing patient size and patient age. The discrepancies in k and q factors across scanners were on average 8% and 15%, respectively. This study demonstrates the feasibility of estimating patient-specific organ dose and cohort-specific effective dose and risk index in abdominopelvic CT requiring only the knowledge of patient size, gender, and age.

Using Dynamic Geometry Software to Improve Eight Grade Students' Understanding of Transformation Geometry

Science.gov (United States)

Guven, Bulent

2012-01-01

This study examines the effect of dynamic geometry software (DGS) on students' learning of transformation geometry. A pre- and post-test quasi-experimental design was used. Participants in the study were 68 eighth grade students (36 in the experimental group and 32 in the control group). While the experimental group students were studying the…

Computer simulations of the influence of geometry in the performance of conventional and unconventional lithium-ion batteries

International Nuclear Information System (INIS)

Miranda, D.; Costa, C.M.; Almeida, A.M.; Lanceros-Méndez, S.

2016-01-01

Highlights: • The influence of geometries in lithium-ion battery performance is analyzed. • Conventional and unconventional battery geometries are investigated. • Unconventional geometries include horseshoe, spiral, ring, antenna and gear batteries. • The best capacity value at 330 C is obtained for the interdigitated geometry. • The capacity value is dependent on thickness and collectors position. - Abstract: In order to optimize battery performance, different geometries have been evaluated taking into account their suitability for different applications. These different geometries include conventional, interdigitated batteries and unconventional geometries such as horseshoe, spiral, ring, antenna and gear batteries. The geometry optimization was performed by the finite element method, applying the Doyle/Fuller/Newman model. At 330 C, the capacity values for conventional, ring, spiral, horseshoe, gear and interdigitated geometries are 0.58 A h m"−"2, 149 A h m"−"2, 182 A h m"−"2, 216 A h m"−"2, 289 A h m"−"2 and 318 A h m"−"2, respectively. The delivered capacity depends on geometrical parameters such as maximum distance for the ions to move to the current collector, d-max, distance between of current collectors, d-cc, as well as the thickness of separator and electrodes, allowing to tailor battery performance and geometry for specific applications.

Erythroid-specific transcriptional changes in PBMCs from pulmonary hypertension patients.

Directory of Open Access Journals (Sweden)

Chris Cheadle

Full Text Available Gene expression profiling of peripheral blood mononuclear cells (PBMCs is a powerful tool for the identification of surrogate markers involved in disease processes. The hypothesis tested in this study was that chronic exposure of PBMCs to a hypertensive environment in remodeled pulmonary vessels would be reflected by specific transcriptional changes in these cells.The transcript profiles of PBMCs from 30 idiopathic pulmonary arterial hypertension patients (IPAH, 19 patients with systemic sclerosis without pulmonary hypertension (SSc, 42 scleroderma-associated pulmonary arterial hypertensio patients (SSc-PAH, and 8 patients with SSc complicated by interstitial lung disease and pulmonary hypertension (SSc-PH-ILD were compared to the gene expression profiles of PBMCs from 41 healthy individuals. Multiple gene expression signatures were identified which could distinguish various disease groups from controls. One of these signatures, specific for erythrocyte maturation, is enriched specifically in patients with PH. This association was validated in multiple published datasets. The erythropoiesis signature was strongly correlated with hemodynamic measures of increasing disease severity in IPAH patients. No significant correlation of the same type was noted for SSc-PAH patients, this despite a clear signature enrichment within this group overall. These findings suggest an association of the erythropoiesis signature in PBMCs from patients with PH with a variable presentation among different subtypes of disease.In PH, the expansion of immature red blood cell precursors may constitute a response to the increasingly hypoxic conditions prevalent in this syndrome. A correlation of this erythrocyte signature with more severe hypertension cases may provide an important biomarker of disease progression.

Boundary Stress-Energy Tensor and Newton-Cartan Geometry in Lifshitz Holography

NARCIS (Netherlands)

Christensen, M.H.; Hartong, J.; Obers, N.A.; Rollier, B.

2014-01-01

For a specific action supporting z = 2 Lifshitz geometries we identify the Lifshitz UV completion by solving for the most general solution near the Lifshitz boundary. We identify all the sources as leading components of bulk fields which requires a vielbein formalism. This includes two linear

Disformal transformation in Newton-Cartan geometry

Energy Technology Data Exchange (ETDEWEB)

Huang, Peng [Zhejiang Chinese Medical University, Department of Information, Hangzhou (China); Sun Yat-Sen University, School of Physics and Astronomy, Guangzhou (China); Yuan, Fang-Fang [Nankai University, School of Physics, Tianjin (China)

2016-08-15

Newton-Cartan geometry has played a central role in recent discussions of the non-relativistic holography and condensed matter systems. Although the conformal transformation in non-relativistic holography can easily be rephrased in terms of Newton-Cartan geometry, we show that it requires a nontrivial procedure to arrive at the consistent form of anisotropic disformal transformation in this geometry. Furthermore, as an application of the newly obtained transformation, we use it to induce a geometric structure which may be seen as a particular non-relativistic version of the Weyl integrable geometry. (orig.)

Atlas-Based Automatic Generation of Subject-Specific Finite Element Tongue Meshes.

Science.gov (United States)

Bijar, Ahmad; Rohan, Pierre-Yves; Perrier, Pascal; Payan, Yohan

2016-01-01

Generation of subject-specific 3D finite element (FE) models requires the processing of numerous medical images in order to precisely extract geometrical information about subject-specific anatomy. This processing remains extremely challenging. To overcome this difficulty, we present an automatic atlas-based method that generates subject-specific FE meshes via a 3D registration guided by Magnetic Resonance images. The method extracts a 3D transformation by registering the atlas' volume image to the subject's one, and establishes a one-to-one correspondence between the two volumes. The 3D transformation field deforms the atlas' mesh to generate the subject-specific FE mesh. To preserve the quality of the subject-specific mesh, a diffeomorphic non-rigid registration based on B-spline free-form deformations is used, which guarantees a non-folding and one-to-one transformation. Two evaluations of the method are provided. First, a publicly available CT-database is used to assess the capability to accurately capture the complexity of each subject-specific Lung's geometry. Second, FE tongue meshes are generated for two healthy volunteers and two patients suffering from tongue cancer using MR images. It is shown that the method generates an appropriate representation of the subject-specific geometry while preserving the quality of the FE meshes for subsequent FE analysis. To demonstrate the importance of our method in a clinical context, a subject-specific mesh is used to simulate tongue's biomechanical response to the activation of an important tongue muscle, before and after cancer surgery.

Some thermo-physical properties of yam cuts of two geometries ...

African Journals Online (AJOL)

The effects of variation of temperature (-18 to 33°C) and geometries (slab and cylinder) on some thermo-physical properties of white yam were investigated. The measured parameters were density, specific heat, and thermal diffusivity at constant moisture level of 72.7% ± 0.69 (wet basis) using transient heat transfer method ...

Patient-specific quality assurance for the delivery of 60Co intensity modulated radiation therapy subject to a 0.35 T lateral magnetic field

Science.gov (United States)

Li, H. Harold; Rodriguez, Vivian L.; Green, Olga L.; Hu, Yanle; Kashani, Rojano; Wooten, H. Omar; Yang, Deshan; Mutic, Sasa

2014-01-01

Purpose This work describes a patient-specific dosimetry quality assurance (QA) program for intensity modulated radiation therapy (IMRT) using ViewRay, the first commercial magnetic resonance imaging guided radiation therapy device. Methods and materials The program consisted of the following components: 1) one-dimensional multipoint ionization chamber measurement using a customized 15 cm3 cubic phantom, 2) two-dimensional (2D) radiographic film measurement using a 30×30×20 cm3 phantom with multiple inserted ionization chambers, 3) quasi- three-dimensional (3D) diode array (ArcCHECK) measurement with a centrally inserted ionization chamber, 4) 2D fluence verification using machine delivery log files, and 5) 3D Monte-Carlo (MC) dose reconstruction with machine delivery files and phantom CT. Results The ionization chamber measurements agreed well with treatment planning system (TPS) computed doses in all phantom geometries where the mean difference (mean ± SD) was 0.0% ± 1.3% (n=102, range, −3.0 % to 2.9%). The film measurements also showed excellent agreement with the TPS computed 2D dose distributions where the mean passing rate using 3% relative/3 mm gamma criteria was 94.6% ± 3.4% (n=30, range, 87.4% to 100%). For ArcCHECK measurements, the mean passing rate using 3% relative/3 mm gamma criteria was 98.9% ± 1.1% (n=34, range, 95.8% to 100%). 2D fluence maps with a resolution of 1×1 mm2 showed 100% passing rates for all plan deliveries (n=34). The MC reconstructed doses to the phantom agreed well with planned 3D doses where the mean passing rate using 3% absolute/3 mm gamma criteria was 99.0% ± 1.0% (n=18, range, 97.0% to100%), demonstrating the feasibility of evaluating the QA results in the patient geometry. Conclusions We have developed a dosimetry program for ViewRay’s patient-specific IMRT QA. The methodology will be useful for other ViewRay users. The QA results presented here can assist the RT community to establish appropriate tolerance and

Patient-Specific Quality Assurance for the Delivery of 60Co Intensity Modulated Radiation Therapy Subject to a 0.35-T Lateral Magnetic Field

International Nuclear Information System (INIS)

Li, H. Harold; Rodriguez, Vivian L.; Green, Olga L.; Hu, Yanle; Kashani, Rojano; Wooten, H. Omar; Yang, Deshan; Mutic, Sasa

2015-01-01

Purpose: This work describes a patient-specific dosimetry quality assurance (QA) program for intensity modulated radiation therapy (IMRT) using ViewRay, the first commercial magnetic resonance imaging-guided RT device. Methods and Materials: The program consisted of: (1) a 1-dimensional multipoint ionization chamber measurement using a customized 15-cm 3 cube-shaped phantom; (2) 2-dimensional (2D) radiographic film measurement using a 30- × 30- × 20-cm 3 phantom with multiple inserted ionization chambers; (3) quasi-3D diode array (ArcCHECK) measurement with a centrally inserted ionization chamber; (4) 2D fluence verification using machine delivery log files; and (5) 3D Monte Carlo (MC) dose reconstruction with machine delivery files and phantom CT. Results: Ionization chamber measurements agreed well with treatment planning system (TPS)-computed doses in all phantom geometries where the mean ± SD difference was 0.0% ± 1.3% (n=102; range, −3.0%-2.9%). Film measurements also showed excellent agreement with the TPS-computed 2D dose distributions where the mean passing rate using 3% relative/3 mm gamma criteria was 94.6% ± 3.4% (n=30; range, 87.4%-100%). For ArcCHECK measurements, the mean ± SD passing rate using 3% relative/3 mm gamma criteria was 98.9% ± 1.1% (n=34; range, 95.8%-100%). 2D fluence maps with a resolution of 1 × 1 mm 2 showed 100% passing rates for all plan deliveries (n=34). The MC reconstructed doses to the phantom agreed well with planned 3D doses where the mean passing rate using 3% absolute/3 mm gamma criteria was 99.0% ± 1.0% (n=18; range, 97.0%-100%), demonstrating the feasibility of evaluating the QA results in the patient geometry. Conclusions: We developed a dosimetry program for ViewRay's patient-specific IMRT QA. The methodology will be useful for other ViewRay users. The QA results presented here can assist the RT community to establish appropriate tolerance and action limits for ViewRay's IMRT

Geometry and symmetry

CERN Document Server

Yale, Paul B

2012-01-01

This book is an introduction to the geometry of Euclidean, affine, and projective spaces with special emphasis on the important groups of symmetries of these spaces. The two major objectives of the text are to introduce the main ideas of affine and projective spaces and to develop facility in handling transformations and groups of transformations. Since there are many good texts on affine and projective planes, the author has concentrated on the n-dimensional cases.Designed to be used in advanced undergraduate mathematics or physics courses, the book focuses on ""practical geometry,"" emphasi

Optimizing solar-cell grid geometry

Science.gov (United States)

Crossley, A. P.

1969-01-01

Trade-off analysis and mathematical expressions calculate optimum grid geometry in terms of various cell parameters. Determination of the grid geometry provides proper balance between grid resistance and cell output to optimize the energy conversion process.

Geometry and Cloaking Devices

Science.gov (United States)

Ochiai, T.; Nacher, J. C.

2011-09-01

Recently, the application of geometry and conformal mappings to artificial materials (metamaterials) has attracted the attention in various research communities. These materials, characterized by a unique man-made structure, have unusual optical properties, which materials found in nature do not exhibit. By applying the geometry and conformal mappings theory to metamaterial science, it may be possible to realize so-called "Harry Potter cloaking device". Although such a device is still in the science fiction realm, several works have shown that by using such metamaterials it may be possible to control the direction of the electromagnetic field at will. We could then make an object hidden inside of a cloaking device. Here, we will explain how to design invisibility device using differential geometry and conformal mappings.

A first course in geometry

CERN Document Server

Walsh, Edward T

2014-01-01

This introductory text is designed to help undergraduate students develop a solid foundation in geometry. Early chapters progress slowly, cultivating the necessary understanding and self-confidence for the more rapid development that follows. The extensive treatment can be easily adapted to accommodate shorter courses. Starting with the language of mathematics as expressed in the algebra of logic and sets, the text covers geometric sets of points, separation and angles, triangles, parallel lines, similarity, polygons and area, circles, space geometry, and coordinate geometry. Each chapter incl

Global affine differential geometry of hypersurfaces

CERN Document Server

Li, An-Min; Zhao, Guosong; Hu, Zejun

2015-01-01

This book draws a colorful and widespread picture of global affine hypersurface theory up to the most recent state. Moreover, the recent development revealed that affine differential geometry- as differential geometry in general- has an exciting intersection area with other fields of interest, like partial differential equations, global analysis, convex geometry and Riemann surfaces.

Spectral dimension of quantum geometries

International Nuclear Information System (INIS)

Calcagni, Gianluca; Oriti, Daniele; Thürigen, Johannes

2014-01-01

The spectral dimension is an indicator of geometry and topology of spacetime and a tool to compare the description of quantum geometry in various approaches to quantum gravity. This is possible because it can be defined not only on smooth geometries but also on discrete (e.g., simplicial) ones. In this paper, we consider the spectral dimension of quantum states of spatial geometry defined on combinatorial complexes endowed with additional algebraic data: the kinematical quantum states of loop quantum gravity (LQG). Preliminarily, the effects of topology and discreteness of classical discrete geometries are studied in a systematic manner. We look for states reproducing the spectral dimension of a classical space in the appropriate regime. We also test the hypothesis that in LQG, as in other approaches, there is a scale dependence of the spectral dimension, which runs from the topological dimension at large scales to a smaller one at short distances. While our results do not give any strong support to this hypothesis, we can however pinpoint when the topological dimension is reproduced by LQG quantum states. Overall, by exploring the interplay of combinatorial, topological and geometrical effects, and by considering various kinds of quantum states such as coherent states and their superpositions, we find that the spectral dimension of discrete quantum geometries is more sensitive to the underlying combinatorial structures than to the details of the additional data associated with them. (paper)

Advanced 3D Mesh Manipulation in Stereolithographic Files and Post-Print Processing for the Manufacturing of Patient-Specific Vascular Flow Phantoms.

Science.gov (United States)

O'Hara, Ryan P; Chand, Arpita; Vidiyala, Sowmya; Arechavala, Stacie M; Mitsouras, Dimitrios; Rudin, Stephen; Ionita, Ciprian N

2016-02-27

Complex vascular anatomies can cause the failure of image-guided endovascular procedures. 3D printed patient-specific vascular phantoms provide clinicians and medical device companies the ability to preemptively plan surgical treatments, test the likelihood of device success, and determine potential operative setbacks. This research aims to present advanced mesh manipulation techniques of stereolithographic (STL) files segmented from medical imaging and post-print surface optimization to match physiological vascular flow resistance. For phantom design, we developed three mesh manipulation techniques. The first method allows outlet 3D mesh manipulations to merge superfluous vessels into a single junction, decreasing the number of flow outlets and making it feasible to include smaller vessels. Next we introduced Boolean operations to eliminate the need to manually merge mesh layers and eliminate errors of mesh self-intersections that previously occurred. Finally we optimize support addition to preserve the patient anatomical geometry. For post-print surface optimization, we investigated various solutions and methods to remove support material and smooth the inner vessel surface. Solutions of chloroform, alcohol and sodium hydroxide were used to process various phantoms and hydraulic resistance was measured and compared with values reported in literature. The newly mesh manipulation methods decrease the phantom design time by 30 - 80% and allow for rapid development of accurate vascular models. We have created 3D printed vascular models with vessel diameters less than 0.5 mm. The methods presented in this work could lead to shorter design time for patient specific phantoms and better physiological simulations.

Algebraic geometry

CERN Document Server

Lefschetz, Solomon

2005-01-01

An introduction to algebraic geometry and a bridge between its analytical-topological and algebraical aspects, this text for advanced undergraduate students is particularly relevant to those more familiar with analysis than algebra. 1953 edition.

A geometry calibration method for rotation translation trajectory

International Nuclear Information System (INIS)

Zhang Jun; Yan Bin; Li Lei; Lu Lizhong; Zhang Feng

2013-01-01

In cone-beam CT imaging system, it is difficult to directly measure the geometry parameters. In this paper, a geometry calibration method for rotation translation trajectory is proposed. Intrinsic parameters are solved from the relationship built on geometry parameter of the system and projection trajectory of calibration object. Parameters of rotation axis are extrapolated from the unified intrinsic parameter, and geometry parameters of the idle trajectory are acquired too. The calibration geometry can be analytically determined using explicit formulae, it can avoid getting into local optimum in iterative way. Simulation experiments are carried out on misaligned geometry, experiment results indicate that geometry artifacts due to misaligned geometry are effectively depressed by the proposed method, and the image quality is enhanced. (authors)

Comparison of serum prostate specific antigen levels and bone scintigraphy in patients with prostate carcinoma

International Nuclear Information System (INIS)

Bielickaite, J.; Zadeikaite, R.; Jurkiene, N. and others

2003-01-01

The aim of this study was to analyze the levels of serum prostate specific antigen in patients with and without bone metastases detected by means of bone scintigraphy and to determine the highest prostate specific antigen level in patients without bone metastases. The 50 patients consecutively diagnosed of prostate cancer between 1999 and 2001 in our institution made up the study population. Prostate specific antigen plasmatic levels were determined and bone scintigraphy was performed (whole body study after 99mTc-methyl-diphosphonate administration) in all the patients. In patients with positive bone scans (n=23), the mean prostate specific antigen level was 71.4±35.2 ng/ml and was significantly (p<0.00005) higher than in 14 patients with negative bone scans (mean prostate specific antigen level was 10.1±10.5 ng/ml). Suspicious lesions were found in 13 patients and their mean prostate specific antigen level was 8.5±7.7 ng/ml. Regarding prostate specific antigen levels, no statistically significant differences were found between patients with suspicious lessons and normal bone scans. The highest determined prostate specific antigen level in patients without bone metastases was 18 ng/ml. The bone scintigraphy should be performed in all patients with prostate specific antigen level above 18 ng/ml, but it is of limited value in patients with prostate specific antigen level below 18 ng/ml. (author)

Modeling and fabrication of an RF MEMS variable capacitor with a fractal geometry

KAUST Repository

Elshurafa, Amro M.

2013-08-16

In this paper, we model, fabricate, and measure an electrostatically actuated MEMS variable capacitor that utilizes a fractal geometry and serpentine-like suspension arms. Explicitly, a variable capacitor that possesses a top suspended plate with a specific fractal geometry and also possesses a bottom fixed plate complementary in shape to the top plate has been fabricated in the PolyMUMPS process. An important benefit that was achieved from using the fractal geometry in designing the MEMS variable capacitor is increasing the tuning range of the variable capacitor beyond the typical ratio of 1.5. The modeling was carried out using the commercially available finite element software COMSOL to predict both the tuning range and pull-in voltage. Measurement results show that the tuning range is 2.5 at a maximum actuation voltage of 10V.

A new experiment-independent mechanism to persistify and serve the detector geometry of ATLAS

Science.gov (United States)

Bianchi, Riccardo Maria; Boudreau, Joseph; Vukotic, Ilija

2017-10-01

The complex geometry of the whole detector of the ATLAS experiment at LHC is currently stored only in custom online databases, from which it is built on-the-fly on request. Accessing the online geometry guarantees accessing the latest version of the detector description, but requires the setup of the full ATLAS software framework “Athena”, which provides the online services and the tools to retrieve the data from the database. This operation is cumbersome and slows down the applications that need to access the geometry. Moreover, all applications that need to access the detector geometry need to be built and run on the same platform as the ATLAS framework, preventing the usage of the actual detector geometry in stand-alone applications. Here we propose a new mechanism to persistify (in software development in general, and in HEP computing in particular, persistifying means taking an object which lives in memory only - for example because it was built on-the-fly while processing the experimental data, - serializing it and storing it on disk as a persistent object) and serve the geometry of HEP experiments. The new mechanism is composed by a new file format and the modules to make use of it. The new file format allows to store the whole detector description locally in a file, and it is especially optimized to describe large complex detectors with the minimum file size, making use of shared instances and storing compressed representations of geometry transformations. Then, the detector description can be read back in, to fully restore the in-memory geometry tree. Moreover, a dedicated REST API is being designed and developed to serve the geometry in standard exchange formats like JSON, to let users and applications download specific partial geometry information. With this new geometry persistification a new generation of applications could be developed, which can use the actual detector geometry while being platform-independent and experiment-independent.

Multiview Discriminative Geometry Preserving Projection for Image Classification

Directory of Open Access Journals (Sweden)

Ziqiang Wang

2014-01-01

Full Text Available In many image classification applications, it is common to extract multiple visual features from different views to describe an image. Since different visual features have their own specific statistical properties and discriminative powers for image classification, the conventional solution for multiple view data is to concatenate these feature vectors as a new feature vector. However, this simple concatenation strategy not only ignores the complementary nature of different views, but also ends up with “curse of dimensionality.” To address this problem, we propose a novel multiview subspace learning algorithm in this paper, named multiview discriminative geometry preserving projection (MDGPP for feature extraction and classification. MDGPP can not only preserve the intraclass geometry and interclass discrimination information under a single view, but also explore the complementary property of different views to obtain a low-dimensional optimal consensus embedding by using an alternating-optimization-based iterative algorithm. Experimental results on face recognition and facial expression recognition demonstrate the effectiveness of the proposed algorithm.

Geometry modeling for SAM-CE Monte Carlo calculations

International Nuclear Information System (INIS)

Steinberg, H.A.; Troubetzkoy, E.S.

1980-01-01

Three geometry packages have been developed and incorporated into SAM-CE, for representing in three dimensions the transport medium. These are combinatorial geometry - a general (non-lattice) system, complex combinatorial geometry - a very general system with lattice capability, and special reactor geometry - a special purpose system for light water reactor geometries. Their different attributes are described

Calculation of coincidence summing corrections for a specific small soil sample geometry

Energy Technology Data Exchange (ETDEWEB)

Helmer, R.G.; Gehrke, R.J.

1996-10-01

Previously, a system was developed at the INEL for measuring the {gamma}-ray emitting nuclides in small soil samples for the purpose of environmental monitoring. These samples were counted close to a {approx}20% Ge detector and, therefore, it was necessary to take into account the coincidence summing that occurs for some nuclides. In order to improve the technical basis for the coincidence summing corrections, the authors have carried out a study of the variation in the coincidence summing probability with position within the sample volume. A Monte Carlo electron and photon transport code (CYLTRAN) was used to compute peak and total efficiencies for various photon energies from 30 to 2,000 keV at 30 points throughout the sample volume. The geometry for these calculations included the various components of the detector and source along with the shielding. The associated coincidence summing corrections were computed at these 30 positions in the sample volume and then averaged for the whole source. The influence of the soil and the detector shielding on the efficiencies was investigated.

Pressure loss coefficient evaluation based on CFD analysis for simple geometries and PWR reactor vessel without geometry simplification

International Nuclear Information System (INIS)

Ko II, B.; Park, J. P.; Jeong, J. H.

2008-01-01

Nuclear vendors and utilities perform lots of simulations and analyses in order to ensure the safe operation of nuclear power plants (NPPs). In general, the simulations are carried out using vendor-specific design codes and best-estimate system analysis codes and most of them were developed based on 1-dimensional lumped parameter models. These thermal-hydraulic system analysis codes require user input for pressure loss coefficient, k-factor; since they numerically solve Euler-equation. In spite of its high impact on the safety analysis results, there has not been good validation method for the selection of loss coefficient. During the past decade, however; computers, parallel computation methods, and 3-dimensional computational fluid dynamics (CFD) codes have been dramatically enhanced. It is believed to be beneficial to take advantage of advanced commercial CFD codes in safety analysis and design of NPP5. The present work aims to validate pressure loss coefficient evaluation for simple geometries and k-factor calculation for PWR based on CFD. The performances of standard k-ε model, RNG k-ε model, Reynolds stress model (RSM) on the simulation of pressure drop for simple geometry such as, or sudden-expansion, and sudden-contraction are evaluated. The calculated value was compared with pressure loss coefficient in handbook of hydraulic resistance. Then the present work carried out analysis for flow distribution in downcomer and lower plenum of Korean standard nuclear power plants (KSNPs) using STAR-CD. The lower plenum geometry of a PWR is very complicated since there are so many reactor internals, which hinders in CFD analysis for real reactor geometry up to now. The present work takes advantage of 3D CAD model so that real geometry of lower plenum is used. The results give a clear figure about flow fields in the reactor vessel, which is one of major safety concerns. The calculated pressure drop across downcomer and lower plenum appears to be in good agreement

Movable geometry and eigenvalue search capability in the MC21 Monte Carlo code

International Nuclear Information System (INIS)

Gill, D. F.; Nease, B. R.; Griesheimer, D. P.

2013-01-01

A description of a robust and flexible movable geometry implementation in the Monte Carlo code MC21 is described along with a search algorithm that can be used in conjunction with the movable geometry capability to perform eigenvalue searches based on the position of some geometric component. The natural use of the combined movement and search capability is searching to critical through variation of control rod (or control drum) position. The movable geometry discussion provides the mathematical framework for moving surfaces in the MC21 combinatorial solid geometry description. A discussion of the interface between the movable geometry system and the user is also described, particularly the ability to create a hierarchy of movable groups. Combined with the hierarchical geometry description in MC21 the movable group framework provides a very powerful system for inline geometry modification. The eigenvalue search algorithm implemented in MC21 is also described. The foundations of this algorithm are a regula falsi search though several considerations are made in an effort to increase the efficiency of the algorithm for use with Monte Carlo. Specifically, criteria are developed to determine after each batch whether the Monte Carlo calculation should be continued, the search iteration can be rejected, or the search iteration has converged. These criteria seek to minimize the amount of time spent per iteration. Results for the regula falsi method are shown, illustrating that the method as implemented is indeed convergent and that the optimizations made ultimately reduce the total computational expense. (authors)

Movable geometry and eigenvalue search capability in the MC21 Monte Carlo code

Energy Technology Data Exchange (ETDEWEB)

Gill, D. F.; Nease, B. R.; Griesheimer, D. P. [Bettis Atomic Power Laboratory, PO Box 79, West Mifflin, PA 15122 (United States)

2013-07-01

A description of a robust and flexible movable geometry implementation in the Monte Carlo code MC21 is described along with a search algorithm that can be used in conjunction with the movable geometry capability to perform eigenvalue searches based on the position of some geometric component. The natural use of the combined movement and search capability is searching to critical through variation of control rod (or control drum) position. The movable geometry discussion provides the mathematical framework for moving surfaces in the MC21 combinatorial solid geometry description. A discussion of the interface between the movable geometry system and the user is also described, particularly the ability to create a hierarchy of movable groups. Combined with the hierarchical geometry description in MC21 the movable group framework provides a very powerful system for inline geometry modification. The eigenvalue search algorithm implemented in MC21 is also described. The foundations of this algorithm are a regula falsi search though several considerations are made in an effort to increase the efficiency of the algorithm for use with Monte Carlo. Specifically, criteria are developed to determine after each batch whether the Monte Carlo calculation should be continued, the search iteration can be rejected, or the search iteration has converged. These criteria seek to minimize the amount of time spent per iteration. Results for the regula falsi method are shown, illustrating that the method as implemented is indeed convergent and that the optimizations made ultimately reduce the total computational expense. (authors)

Patient-specific prediction of functional recovery after stroke.

Science.gov (United States)

Douiri, Abdel; Grace, Justin; Sarker, Shah-Jalal; Tilling, Kate; McKevitt, Christopher; Wolfe, Charles DA; Rudd, Anthony G

2017-07-01

Background and aims Clinical predictive models for stroke recovery could offer the opportunity of targeted early intervention and more specific information for patients and carers. In this study, we developed and validated a patient-specific prognostic model for monitoring recovery after stroke and assessed its clinical utility. Methods Four hundred and ninety-five patients from the population-based South London Stroke Register were included in a substudy between 2002 and 2004. Activities of daily living were assessed using Barthel Index) at one, two, three, four, six, eight, 12, 26, and 52 weeks after stroke. Penalized linear mixed models were developed to predict patients' functional recovery trajectories. An external validation cohort included 1049 newly registered stroke patients between 2005 and 2011. Prediction errors on discrimination and calibration were assessed. The potential clinical utility was evaluated using prognostic accuracy measurements and decision curve analysis. Results Predictive recovery curves showed good accuracy, with root mean squared deviation of 3 Barthel Index points and a R 2 of 83% up to one year after stroke in the external cohort. The negative predictive values of the risk of poor recovery (Barthel Index <8) at three and 12 months were also excellent, 96% (95% CI [93.6-97.4]) and 93% [90.8-95.3], respectively, with a potential clinical utility measured by likelihood ratios (LR+:17 [10.8-26.8] at three months and LR+:11 [6.5-17.2] at 12 months). Decision curve analysis showed an increased clinical benefit, particularly at threshold probabilities of above 5% for predictive risk of poor outcomes. Conclusions A recovery curves tool seems to accurately predict progression of functional recovery in poststroke patients.

Effect of discharge duct geometry on centrifugal fan performance and noise emission

Science.gov (United States)

Nelson, David A.; Butrymowicz, William; Thomas, Christopher

2005-09-01

Non-ideal inlet and discharge duct geometries can cause significant changes to both the aerodynamic performance (``fan curve'') and specific sound power emission of a fan. A proper understanding of actual installed performance, as well as a good estimate of the system backpressure curve, is critical to achieving flow and acoustic goals as well as other criteria such as power consumption, mass and volume. To this end a battery of ISO 10302 tests was performed on a blower assembly which supports the Advanced Animal Habitat, being developed by ORBITEC for deployment on the International Space Station. The blower assembly consists of (4) identical centrifugal fans that, amongst themselves and across two prototypes, incorporated several discharge geometries. The inlet geometries were identical in all cases. Thus by comparing the dimensionless pressure-flow and noise emission characteristics across the cases, significant insight into the nature and potential magnitude of these effects is gained.

Molecular motion in restricted geometries

Indian Academy of Sciences (India)

Molecular dynamics in restricted geometries is known to exhibit anomalous behaviour. Diffusion, translational or rotational, of molecules is altered significantly on confinement in restricted geometries. Quasielastic neutron scattering (QENS) offers a unique possibility of studying molecular motion in such systems. Both time ...

Advances in discrete differential geometry

CERN Document Server

2016-01-01

This is one of the first books on a newly emerging field of discrete differential geometry and an excellent way to access this exciting area. It surveys the fascinating connections between discrete models in differential geometry and complex analysis, integrable systems and applications in computer graphics. The authors take a closer look at discrete models in differential geometry and dynamical systems. Their curves are polygonal, surfaces are made from triangles and quadrilaterals, and time is discrete. Nevertheless, the difference between the corresponding smooth curves, surfaces and classical dynamical systems with continuous time can hardly be seen. This is the paradigm of structure-preserving discretizations. Current advances in this field are stimulated to a large extent by its relevance for computer graphics and mathematical physics. This book is written by specialists working together on a common research project. It is about differential geometry and dynamical systems, smooth and discrete theories, ...

Geometry optimization method versus predictive ability in QSPR modeling for ionic liquids

Science.gov (United States)

Rybinska, Anna; Sosnowska, Anita; Barycki, Maciej; Puzyn, Tomasz

2016-02-01

Computational techniques, such as Quantitative Structure-Property Relationship (QSPR) modeling, are very useful in predicting physicochemical properties of various chemicals. Building QSPR models requires calculating molecular descriptors and the proper choice of the geometry optimization method, which will be dedicated to specific structure of tested compounds. Herein, we examine the influence of the ionic liquids' (ILs) geometry optimization methods on the predictive ability of QSPR models by comparing three models. The models were developed based on the same experimental data on density collected for 66 ionic liquids, but with employing molecular descriptors calculated from molecular geometries optimized at three different levels of the theory, namely: (1) semi-empirical (PM7), (2) ab initio (HF/6-311+G*) and (3) density functional theory (B3LYP/6-311+G*). The model in which the descriptors were calculated by using ab initio HF/6-311+G* method indicated the best predictivity capabilities ({{Q}}_{{EXT}}2 = 0.87). However, PM7-based model has comparable values of quality parameters ({{Q}}_{{EXT}}2 = 0.84). Obtained results indicate that semi-empirical methods (faster and less expensive regarding CPU time) can be successfully employed to geometry optimization in QSPR studies for ionic liquids.

An Investigation into Conversion from Non-Uniform Rational B-Spline Boundary Representation Geometry to Constructive Solid Geometry

Science.gov (United States)

2015-12-01

ARL-SR-0347 ● DEC 2015 US Army Research Laboratory An Investigation into Conversion from Non-Uniform Rational B-Spline Boundary...US Army Research Laboratory An Investigation into Conversion from Non-Uniform Rational B-Spline Boundary Representation Geometry to...from Non-Uniform Rational B-Spline Boundary Representation Geometry to Constructive Solid Geometry 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

W-geometry

International Nuclear Information System (INIS)

Hull, C.M.

1993-01-01

The geometric structure of theories with gauge fields of spins two and higher should involve a higher spin generalisation of Riemannian geometry. Such geometries are discussed and the case of W ∝ -gravity is analysed in detail. While the gauge group for gravity in d dimensions is the diffeomorphism group of the space-time, the gauge group for a certain W-gravity theory (which is W ∝ -gravity in the case d=2) is the group of symplectic diffeomorphisms of the cotangent bundle of the space-time. Gauge transformations for W-gravity gauge fields are given by requiring the invariance of a generalised line element. Densities exist and can be constructed from the line element (generalising √detg μν ) only if d=1 or d=2, so that only for d=1,2 can actions be constructed. These two cases and the corresponding W-gravity actions are considered in detail. In d=2, the gauge group is effectively only a subgroup of the symplectic diffeomorphisms group. Some of the constraints that arise for d=2 are similar to equations arising in the study of self-dual four-dimensional geometries and can be analysed using twistor methods, allowing contact to be made with other formulations of W-gravity. While the twistor transform for self-dual spaces with one Killing vector reduces to a Legendre transform, that for two Killing vectors gives a generalisation of the Legendre transform. (orig.)

Prime factorization using quantum annealing and computational algebraic geometry

Science.gov (United States)

Dridi, Raouf; Alghassi, Hedayat

2017-02-01

We investigate prime factorization from two perspectives: quantum annealing and computational algebraic geometry, specifically Gröbner bases. We present a novel autonomous algorithm which combines the two approaches and leads to the factorization of all bi-primes up to just over 200000, the largest number factored to date using a quantum processor. We also explain how Gröbner bases can be used to reduce the degree of Hamiltonians.

Prime factorization using quantum annealing and computational algebraic geometry

OpenAIRE

Dridi, Raouf; Alghassi, Hedayat

2017-01-01

We investigate prime factorization from two perspectives: quantum annealing and computational algebraic geometry, specifically Gr?bner bases. We present a novel autonomous algorithm which combines the two approaches and leads to the factorization of all bi-primes up to just over 200000, the largest number factored to date using a quantum processor. We also explain how Gr?bner bases can be used to reduce the degree of Hamiltonians.

Patient-Specific Dosimetry of Pretargeted Radioimmunotherapy Using CC49 Fusion Protein in Patients with Gastrointestinal Malignancies

International Nuclear Information System (INIS)

Shen, Shang; Forero, Andres; LoBuglio, Albert F.; Breitz, H.; Khazaeli, M. B.; Fisher, Darrell R.; Wang, W. Q.; Meredith, Ruby F.

2005-01-01

Patient-Specific Dosimetry of Pretargeted Radioimmunotherapy Using CC49 Fusion Protein in Patients with Gastrointestinal Malignancies. Shen S, Forero A, Lobuglio AF, Breitz H, Khazaeli MB, Fisher DR, Wang W, Meredith RF. Department of Radiation Oncology, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama, and Radioisotopes Program at Pacific Northwest National Laboratory, Richland, Washington. Pretargeted radioimmunotherapy (RIT) using CC49 fusion protein, comprised of CC49-(scFv)(4) and streptavidin, in conjunction with (90)Y/(111)In-DOTA-biotin (DOTA = dodecanetetraacetic acid) provides a new opportunity to improve efficacy by increasing the tumor-to-normal tissue dose ratio. To our knowledge, the patient-specific dosimetry of pretargeted (90)Y/(111)In-DOTA-biotin after CC49 fusion protein in patients has not been reported previously. METHODS: Nine patients received 3-step pretargeted RIT: (a) 160 mg/m(2) of CC49 fusion protein, (b) synthetic clearing agent (sCA) at 48 or 72 h later, and (c) (90)Y/(111)In-DOTA-biotin 24 h after the sCA administration. Sequential whole-body (111)In images were acquired immediately and at 2-144 h after injection of (90)Y/(111)In-DOTA-biotin. Geometric-mean quantification with background and attenuation correction was used for liver and lung dosimetry. Effective point source quantification was used for spleen, kidneys, and tumors. Organ and tumor (90)Y doses were calculated based on (111)In imaging data and the MIRD formalism using patient-specific organ masses determined from CT images. Patient-specific marrow doses were determined based on radioactivity concentration in the blood. RESULTS: The (90)Y/(111)In-DOTA-biotin had a rapid plasma clearance, which was biphasic with <10% residual at 8 h. Organ masses ranged from 1,263 to 3,855 g for liver, 95 to 1,009 g for spleen, and 309 to 578 g for kidneys. The patient-specific mean (90)Y dose (cGy/37 MBq, or rad/mCi) was 0.53 (0.32-0.78) to whole body

Head First 2D Geometry

CERN Document Server

Fallow), Stray

2009-01-01

Having trouble with geometry? Do Pi, The Pythagorean Theorem, and angle calculations just make your head spin? Relax. With Head First 2D Geometry, you'll master everything from triangles, quads and polygons to the time-saving secrets of similar and congruent angles -- and it'll be quick, painless, and fun. Through entertaining stories and practical examples from the world around you, this book takes you beyond boring problems. You'll actually use what you learn to make real-life decisions, like using angles and parallel lines to crack a mysterious CSI case. Put geometry to work for you, and

Numerically robust geometry engine for compound solid geometries

International Nuclear Information System (INIS)

Vlachoudis, V.; Sinuela-Pastor, D.

2013-01-01

Monte Carlo programs heavily rely on a fast and numerically robust solid geometry engines. However the success of solid modeling, depends on facilities for specifying and editing parameterized models through a user-friendly graphical front-end. Such a user interface has to be fast enough in order to be interactive for 2D and/or 3D displays, but at the same time numerically robust in order to display possible modeling errors at real time that could be critical for the simulation. The graphical user interface Flair for FLUKA currently employs such an engine where special emphasis has been given on being fast and numerically robust. The numerically robustness is achieved by a novel method of estimating the floating precision of the operations, which dynamically adapts all the decision operations accordingly. Moreover a predictive caching mechanism is ensuring that logical errors in the geometry description are found online, without compromising the processing time by checking all regions. (authors)

Magnetic response of certain curved graphitic geometries

International Nuclear Information System (INIS)

Wang, L.; Davids, P.S.; Saxena, A.; Bishop, A.R.

1992-01-01

The quasi-particle energy spectra associated with some members of buckyfamily (curved graphitic geometries), in particular C 50 , C 60 , C 70 and related fullerenes as well as coaxial helical microtubules of graphite, are obtained analytically within the mean-field approximation. These energy spectra are then used to calculate various response functions. Specifically, we calculate the specific heat, magnetization and magnetic susceptibility in the presence of an external magnetic field at low temperatures. For a single microtubule an extra peak superimposed on the first de Haas van Alphen (dHvA) oscillation in magnetic susceptibility is found in the 50--170 Tesla range depending on the radius which is possibly accessible in special (explosive flux compression) experiments. Finally, we point to important potential applications of these novel mesoscopic structures in nanotechnology

Quantification of Porcine Vocal Fold Geometry.

Science.gov (United States)

Stevens, Kimberly A; Thomson, Scott L; Jetté, Marie E; Thibeault, Susan L

2016-07-01

The aim of this study was to quantify porcine vocal fold medial surface geometry and three-dimensional geometric distortion induced by freezing the larynx, especially in the region of the vocal folds. The medial surface geometries of five excised porcine larynges were quantified and reported. Five porcine larynges were imaged in a micro-CT scanner, frozen, and rescanned. Segmentations and three-dimensional reconstructions were used to quantify and characterize geometric features. Comparisons were made with geometry data previously obtained using canine and human vocal folds as well as geometries of selected synthetic vocal fold models. Freezing induced an overall expansion of approximately 5% in the transverse plane and comparable levels of nonuniform distortion in sagittal and coronal planes. The medial surface of the porcine vocal folds was found to compare reasonably well with other geometries, although the compared geometries exhibited a notable discrepancy with one set of published human female vocal fold geometry. Porcine vocal folds are qualitatively geometrically similar to data available for canine and human vocal folds, as well as commonly used models. Freezing of tissue in the larynx causes distortion of around 5%. The data can provide direction in estimating uncertainty due to bulk distortion of tissue caused by freezing, as well as quantitative geometric data that can be directly used in developing vocal fold models. Copyright © 2016 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Lectures on discrete geometry

CERN Document Server

2002-01-01

Discrete geometry investigates combinatorial properties of configurations of geometric objects. To a working mathematician or computer scientist, it offers sophisticated results and techniques of great diversity and it is a foundation for fields such as computational geometry or combinatorial optimization. This book is primarily a textbook introduction to various areas of discrete geometry. In each area, it explains several key results and methods, in an accessible and concrete manner. It also contains more advanced material in separate sections and thus it can serve as a collection of surveys in several narrower subfields. The main topics include: basics on convex sets, convex polytopes, and hyperplane arrangements; combinatorial complexity of geometric configurations; intersection patterns and transversals of convex sets; geometric Ramsey-type results; polyhedral combinatorics and high-dimensional convexity; and lastly, embeddings of finite metric spaces into normed spaces. Jiri Matousek is Professor of Com...

Discrete and computational geometry

CERN Document Server

Devadoss, Satyan L

2011-01-01

Discrete geometry is a relatively new development in pure mathematics, while computational geometry is an emerging area in applications-driven computer science. Their intermingling has yielded exciting advances in recent years, yet what has been lacking until now is an undergraduate textbook that bridges the gap between the two. Discrete and Computational Geometry offers a comprehensive yet accessible introduction to this cutting-edge frontier of mathematics and computer science. This book covers traditional topics such as convex hulls, triangulations, and Voronoi diagrams, as well as more recent subjects like pseudotriangulations, curve reconstruction, and locked chains. It also touches on more advanced material, including Dehn invariants, associahedra, quasigeodesics, Morse theory, and the recent resolution of the Poincaré conjecture. Connections to real-world applications are made throughout, and algorithms are presented independently of any programming language. This richly illustrated textbook also fe...

A prediction for bubbling geometries

OpenAIRE

Okuda, Takuya

2007-01-01

We study the supersymmetric circular Wilson loops in N=4 Yang-Mills theory. Their vacuum expectation values are computed in the parameter region that admits smooth bubbling geometry duals. The results are a prediction for the supergravity action evaluated on the bubbling geometries for Wilson loops.

Geometry and self-righting of turtles.

Science.gov (United States)

Domokos, Gábor; Várkonyi, Péter L

2008-01-07

Terrestrial animals with rigid shells face imminent danger when turned upside down. A rich variety of righting strategies of beetle and turtle species have been described, but the exact role of the shell's geometry in righting is so far unknown. These strategies are often based on active mechanisms, e.g. most beetles self-right via motion of their legs or wings; flat, aquatic turtles use their muscular neck to flip back. On the other hand, highly domed, terrestrial turtles with short limbs and necks have virtually no active control: here shape itself may serve as a fundamental tool. Based on field data gathered on a broad spectrum of aquatic and terrestrial turtle species we develop a geometric model of the shell. Inspired by recent mathematical results, we demonstrate that a simple mechanical classification of the model is closely linked to the animals' righting strategy. Specifically, we show that the exact geometry of highly domed terrestrial species is close to optimal for self-righting, and the shell's shape is the predominant factor of their ability to flip back. Our study illustrates how evolution solved a far-from-trivial geometrical problem and equipped some turtles with monostatic shells: beautiful forms, which rarely appear in nature otherwise.

Geometry effects on magnetization dynamics in circular cross-section wires

Energy Technology Data Exchange (ETDEWEB)

Sturma, M. [Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble (France); CNRS, SPINTEC, F-38000 Grenoble (France); CEA, INAC-SPINTEC, F-38000 Grenoble (France); Univ. Grenoble Alpes, I. Neel, F-38000 Grenoble (France); CNRS, I. Neel, F-38000 Grenoble (France); Toussaint, J.-C., E-mail: jean-christophe.toussaint@neel.cnrs.fr, E-mail: daria.gusakova@cea.fr [Univ. Grenoble Alpes, I. Neel, F-38000 Grenoble (France); CNRS, I. Neel, F-38000 Grenoble (France); Gusakova, D., E-mail: jean-christophe.toussaint@neel.cnrs.fr, E-mail: daria.gusakova@cea.fr [Univ. Grenoble Alpes, INAC-SPINTEC, F-38000 Grenoble (France); CNRS, SPINTEC, F-38000 Grenoble (France); CEA, INAC-SPINTEC, F-38000 Grenoble (France)

2015-06-28

Three-dimensional magnetic memory design based on circular-cross section nanowires with modulated diameter is the emerging field of spintronics. The consequences of the mutual interaction between electron spins and local magnetic moments in such non-trivial geometries are still open to debate. This paper describes the theoretical study of domain wall dynamics within such wires subjected to spin polarized current. We used our home-made finite element software to characterize the variety of domain wall dynamical regimes observed for different constriction to wire diameter ratios d/D. Also, we studied how sizeable geometry irregularities modify the internal micromagnetic configuration and the electron spin spatial distribution in the system, the geometrical reasons underlying the additional contribution to the system's nonadiabaticity, and the specific domain wall width oscillations inherent to fully three-dimensional systems.

Geometry -----------~--------------RESONANCE

Indian Academy of Sciences (India)

Parallel: A pair of lines in a plane is said to be parallel if they do not meet. Mathematicians were at war ... Subsequently, Poincare, Klein, Beltrami and others refined non-. Euclidean geometry. ... plane divides the plane into two half planes and.

Direct fabrication of bio-inspired gecko-like geometries with vat polymerization additive manufacturing method

DEFF Research Database (Denmark)

Davoudinejad, A.; M. Ribo, M.; Pedersen, D. B.

2018-01-01

on. The geometry and fabrication of these surfaces are still under research. In this study, the feasibility of using direct fabrication of microscale features by Additive Manufacturing (AM) processes was investigated. The investigation was carried out using a specifically designed vat...... photopolymerization AM machine-tool suitable for precision manufacturing at the micro dimensional scale which has previously been developed, built and validated at the Technical University of Denmark. It was shown that it was possible to replicate a simplified surface inspired by the Tokay gecko, the geometry...

Intermediate algebra & analytic geometry

CERN Document Server

Gondin, William R

1967-01-01

Intermediate Algebra & Analytic Geometry Made Simple focuses on the principles, processes, calculations, and methodologies involved in intermediate algebra and analytic geometry. The publication first offers information on linear equations in two unknowns and variables, functions, and graphs. Discussions focus on graphic interpretations, explicit and implicit functions, first quadrant graphs, variables and functions, determinate and indeterminate systems, independent and dependent equations, and defective and redundant systems. The text then examines quadratic equations in one variable, system

Adaptive grid generation in a patient-specific cerebral aneurysm

Science.gov (United States)

Hodis, Simona; Kallmes, David F.; Dragomir-Daescu, Dan

2013-11-01

computational time for patient-specific hemodynamics simulations, which are used to help assess the likelihood of aneurysm rupture using CFD calculated flow patterns.

The effect of patient-specific factors on radiation-induced regional lung injury

International Nuclear Information System (INIS)

Garipagaoglu, Melahat; Munley, Michael T.; Hollis, Donna; Poulson, Jean M.; Bentel, Gunilla C.; Sibley, Gregory; Anscher, Mitchell S.; Fan Ming; Jaszczak, Ronald J.; Coleman, R. Edward; Marks, Lawrence B.

1999-01-01

Purpose: To assess the impact of patient-specific factors on radiation (RT)-induced reductions in regional lung perfusion. Methods: Fifty patients (32 lung carcinoma, 7 Hodgkin's disease, 9 breast carcinoma and 2 other thoracic tumors) had pre-RT and ≥24-week post-RT single photon emission computed tomography (SPECT) perfusion images to assess the dose dependence of RT-induced reductions in regional lung perfusion. The SPECT data were analyzed using a normalized and non-normalized approach. Furthermore, two different mathematical methods were used to assess the impact of patient-specific factors on the dose-response curve (DRC). First, DRCs for different patient subgroups were generated and compared. Second, in a more formal statistical approach, individual DRCs for regional lung injury for each patient were fit to a linear-quadratic model (reduction = coefficient 1 x dose + coefficient 2 x dose 2 ). Multiple patient-specific factors including tobacco history, pre-RT diffusion capacity to carbon monoxide (DLCO), transforming growth factor-beta (TGF-β), chemotherapy exposure, disease type, and mean lung dose were explored in a multivariate analysis to assess their impact on the coefficients. Results: None of the variables tested had a consistent impact on the radiation sensitivity of regional lung (i.e., the slope of the DRC). In the formal statistical analysis, there was a suggestion of a slight increase in radiation sensitivity in the dose range >40 Gy for nonsmokers (vs. smokers) and in those receiving chemotherapy (vs. no chemotherapy). However, this finding was very dependent on the specific statistical and normalization method used. Conclusion: Patient-specific factors do not have a dramatic effect on RT-induced reduction in regional lung perfusion. Additional studies are underway to better clarify this issue. We continue to postulate that patient-specific factors will impact on how the summation of regional injury translates into whole organ injury

A Geometry Based Infra-Structure for Computational Analysis and Design

Science.gov (United States)

Haimes, Robert

1998-01-01

The computational steps traditionally taken for most engineering analysis suites (computational fluid dynamics (CFD), structural analysis, heat transfer and etc.) are: (1) Surface Generation -- usually by employing a Computer Assisted Design (CAD) system; (2) Grid Generation -- preparing the volume for the simulation; (3) Flow Solver -- producing the results at the specified operational point; (4) Post-processing Visualization -- interactively attempting to understand the results. For structural analysis, integrated systems can be obtained from a number of commercial vendors. These vendors couple directly to a number of CAD systems and are executed from within the CAD Graphical User Interface (GUI). It should be noted that the structural analysis problem is more tractable than CFD; there are fewer mesh topologies used and the grids are not as fine (this problem space does not have the length scaling issues of fluids). For CFD, these steps have worked well in the past for simple steady-state simulations at the expense of much user interaction. The data was transmitted between phases via files. In most cases, the output from a CAD system could go to Initial Graphics Exchange Specification (IGES) or Standard Exchange Program (STEP) files. The output from Grid Generators and Solvers do not really have standards though there are a couple of file formats that can be used for a subset of the gridding (i.e. PLOT3D data formats). The user would have to patch up the data or translate from one format to another to move to the next step. Sometimes this could take days. Specifically the problems with this procedure are:(1) File based -- Information flows from one step to the next via data files with formats specified for that procedure. File standards, when they exist, are wholly inadequate. For example, geometry from CAD systems (transmitted via IGES files) is defined as disjoint surfaces and curves (as well as masses of other information of no interest for the Grid Generator

Geometry and transport in a model of two coupled quadratic nonlinear waveguides

DEFF Research Database (Denmark)

Stirling, James R.; Bang, Ole; Christiansen, Peter Leth

2008-01-01

This paper applies geometric methods developed to understand chaos and transport in Hamiltonian systems to the study of power distribution in nonlinear waveguide arrays. The specific case of two linearly coupled X(2) waveguides is modeled and analyzed in terms of transport and geometry in the pha...

Patient-specific estimation of detailed cochlear shape from clinical CT images

DEFF Research Database (Denmark)

Kjer, H Martin; Fagertun, Jens; Wimmer, Wilhelm

2018-01-01

of the detailed patient-specific cochlear shape from CT images. From a collection of temporal bone [Formula: see text]CT images, we build a cochlear statistical deformation model (SDM), which is a description of how a human cochlea deforms to represent the observed anatomical variability. The model is used...... for regularization of a non-rigid image registration procedure between a patient CT scan and a [Formula: see text]CT image, allowing us to estimate the detailed patient-specific cochlear shape. We test the accuracy and precision of the predicted cochlear shape using both [Formula: see text]CT and CT images...

Geometry The Language of Space and Form (Revised Edition)

CERN Document Server

Tabak, John

2011-01-01

Geometry, Revised Edition describes geometry in antiquity. Beginning with a brief description of some of the geometry that preceded the geometry of the Greeks, it takes up the story of geometry during the European Renaissance as well as the significant mathematical progress in other areas of the world. It also discusses the analytic geometry of Ren Descartes and Pierre Fermat, the alternative coordinate systems invented by Isaac Newton, and the solid geometry of Leonhard Euler. Also included is an overview of the geometry of one of the most successful mathematicians of the 19th century, Bernha

Patient-specific dose estimation for pediatric chest CT

Energy Technology Data Exchange (ETDEWEB)

Li Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Frush, Donald P. [Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 and Department of Radiology, Duke Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 (United States); Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States); Department of Radiology, Duke Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 (United States); Department of Physics, Duke University, Durham, North Carolina 27710 (United States); and Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708 (United States); Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 and Department of Radiology, Duke Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 (United States); Department of Radiology, Duke Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 (United States); Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 and Global Applied Science Laboratory, GE Healthcare, Waukesha, Wisconsin 53188 (United States); Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 and Department of Radiology, Division of Pediatric Radiology, Duke University Medical Center, Durham North Carolina 27710 (United States)

2008-12-15

Current methods for organ and effective dose estimations in pediatric CT are largely patient generic. Physical phantoms and computer models have only been developed for standard/limited patient sizes at discrete ages (e.g., 0, 1, 5, 10, 15 years old) and do not reflect the variability of patient anatomy and body habitus within the same size/age group. In this investigation, full-body computer models of seven pediatric patients in the same size/protocol group (weight: 11.9-18.2 kg) were created based on the patients' actual multi-detector array CT (MDCT) data. Organs and structures in the scan coverage were individually segmented. Other organs and structures were created by morphing existing adult models (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. Organ and effective dose of these patients from a chest MDCT scan protocol (64 slice LightSpeed VCT scanner, 120 kVp, 70 or 75 mA, 0.4 s gantry rotation period, pitch of 1.375, 20 mm beam collimation, and small body scan field-of-view) was calculated using a Monte Carlo program previously developed and validated to simulate radiation transport in the same CT system. The seven patients had normalized effective dose of 3.7-5.3 mSv/100 mAs (coefficient of variation: 10.8%). Normalized lung dose and heart dose were 10.4-12.6 mGy/100 mAs and 11.2-13.3 mGy/100 mAs, respectively. Organ dose variations across the patients were generally small for large organs in the scan coverage (<7%), but large for small organs in the scan coverage (9%-18%) and for partially or indirectly exposed organs (11%-77%). Normalized effective dose correlated weakly with body weight (correlation coefficient: r=-0.80). Normalized lung dose and heart dose correlated strongly with mid-chest equivalent diameter (lung: r=-0.99, heart: r=-0.93); these strong correlation relationships can be used to estimate patient-specific organ

Systematic Review of Patient-Specific Surgical Simulation: Toward Advancing Medical Education.

Science.gov (United States)

Ryu, Won Hyung A; Dharampal, Navjit; Mostafa, Ahmed E; Sharlin, Ehud; Kopp, Gail; Jacobs, William Bradley; Hurlbert, Robin John; Chan, Sonny; Sutherland, Garnette R

Simulation-based education has been shown to be an effective tool to teach foundational technical skills in various surgical specialties. However, most of the current simulations are limited to generic scenarios and do not allow continuation of the learning curve beyond basic technical skills to prepare for more advanced expertise, such as patient-specific surgical planning. The objective of this study was to evaluate the current medical literature with respect to the utilization and educational value of patient-specific simulations for surgical training. We performed a systematic review of the literature using Pubmed, Embase, and Scopus focusing on themes of simulation, patient-specific, surgical procedure, and education. The study included randomized controlled trials, cohort studies, and case-control studies published between 2005 and 2016. Two independent reviewers (W.H.R. and N.D) conducted the study appraisal, data abstraction, and quality assessment of the studies. The search identified 13 studies that met the inclusion criteria; 7 studies employed computer simulations and 6 studies used 3-dimensional (3D) synthetic models. A number of surgical specialties evaluated patient-specific simulation, including neurosurgery, vascular surgery, orthopedic surgery, and interventional radiology. However, most studies were small in size and primarily aimed at feasibility assessments and early validation. Early evidence has shown feasibility and utility of patient-specific simulation for surgical education. With further development of this technology, simulation-based education may be able to support training of higher-level competencies outside the clinical settingto aid learners in their development of surgical skills. Copyright © 2017 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

From geometry to algebra and vice versa: Realistic mathematics education principles for analyzing geometry tasks

Science.gov (United States)

Jupri, Al

2017-04-01

In this article we address how Realistic Mathematics Education (RME) principles, including the intertwinement and the reality principles, are used to analyze geometry tasks. To do so, we carried out three phases of a small-scale study. First we analyzed four geometry problems - considered as tasks inviting the use of problem solving and reasoning skills - theoretically in the light of the RME principles. Second, we tested two problems to 31 undergraduate students of mathematics education program and other two problems to 16 master students of primary mathematics education program. Finally, we analyzed student written work and compared these empirical to the theoretical results. We found that there are discrepancies between what we expected theoretically and what occurred empirically in terms of mathematization and of intertwinement of mathematical concepts from geometry to algebra and vice versa. We conclude that the RME principles provide a fruitful framework for analyzing geometry tasks that, for instance, are intended for assessing student problem solving and reasoning skills.

Differential geometry curves, surfaces, manifolds

CERN Document Server

Kohnel, Wolfgang

2002-01-01

This carefully written book is an introduction to the beautiful ideas and results of differential geometry. The first half covers the geometry of curves and surfaces, which provide much of the motivation and intuition for the general theory. Special topics that are explored include Frenet frames, ruled surfaces, minimal surfaces and the Gauss-Bonnet theorem. The second part is an introduction to the geometry of general manifolds, with particular emphasis on connections and curvature. The final two chapters are insightful examinations of the special cases of spaces of constant curvature and Einstein manifolds. The text is illustrated with many figures and examples. The prerequisites are undergraduate analysis and linear algebra.

Projective Geometry

Indian Academy of Sciences (India)

mathematicians are trained to use very precise language, and so find it hard to simplify and state .... thing. If you take a plane on which there are two such triangles which enjoy the above ... within this geometry to simplify things if needed.

Towards patient specific thermal modelling of the prostate

International Nuclear Information System (INIS)

Berg, Cornelis A T van den; Kamer, Jeroen B van de; Leeuw, Astrid A C ee; Jeukens, Cecile R L P N; Raaymakers, Bas W; Vulpen, Marco van; Lagendijk, Jan J W

2006-01-01

The application of thermal modelling for hyperthermia and thermal ablation is severely hampered by lack of information about perfusion and vasculature. However, recently, with the advent of sophisticated angiography and dynamic contrast enhanced (DCE) imaging techniques, it has become possible to image small vessels and blood perfusion bringing the ultimate goal of patient specific thermal modelling closer within reach. In this study dynamic contrast enhanced multi-slice CT imaging techniques are employed to investigate the feasibility of this concept for regional hyperthermia treatment of the prostate. The results are retrospectively compared with clinical thermometry data of a patient group from an earlier trial. Furthermore, the role of the prostate vasculature in the establishment of the prostate temperature distribution is studied. Quantitative 3D perfusion maps of the prostate were constructed for five patients using a distributed-parameter tracer kinetics model to analyse dynamic CT data. CT angiography was applied to construct a discrete vessel model of the pelvis. Additionally, a discrete vessel model of the prostate vasculature was constructed of a prostate taken from a human corpse. Three thermal modelling schemes with increasing inclusion of the patient specific physiological information were used to simulate the temperature distribution of the prostate during regional hyperthermia. Prostate perfusion was found to be heterogeneous and T3 prostate carcinomas are often characterized by a strongly elevated tumour perfusion (up to 70-80 ml 100 g -1 min -1 ). This elevated tumour perfusion leads to 1-2 deg. C lower tumour temperatures than thermal simulations based on a homogeneous prostate perfusion. Furthermore, the comparison has shown that the simulations with the measured perfusion maps result in consistently lower prostate temperatures than clinically achieved. The simulations with the discrete vessel model indicate that significant pre-heating takes

HPV specific testing: a requirement for oropharyngeal squamous cell carcinoma patients.

Science.gov (United States)

Robinson, Max; Schache, Andrew; Sloan, Philip; Thavaraj, Selvam

2012-07-01

Human papillomavirus (HPV) testing is now recommended as part of the work up for patients with oropharyngeal squamous cell carcinoma (OPSCC) and those patients with cervical lymph node metastasis of unknown origin. The laboratory testing strategy should accurately assess the presence or absence of oncogenic HPV infection in routinely collected tumour samples that are subject to standard fixation protocols, alcohol-fixed cytological preparations and formalin-fixed tissue samples. The HPV status should correlate with biologically relevant outcome measures such as overall, disease-specific and disease-free survival. Whilst increased expression of p16 by immunohistochemistry is considered to be a surrogate marker of oncogenic HPV infection and is a validated independent prognostic biomarker, only HPV specific tests provide definitive evidence of the aetiological agent. We provide an overview of HPV testing in OPSCC, justifying the use of HPV specific tests. We examine the analytical accuracy of HPV specific tests against the 'reference' test--high risk HPV mRNA in fresh tissue--and contrast this with the performance of p16 immunohistochemistry as a stand alone test. We highlight the added value of HPV specific tests in prognostication, clinical trial design, and population-based disease surveillance. We consider that HPV specific testing is the starting point for developing increasingly informative biomarker panels in the context of 'stratified medicine'. We briefly frame test information in the context of disclosure of HPV status to patients. We conclude that only a testing strategy that includes HPV specific tests can deliver more effective care for patients with OPSCC. The international head and neck oncology community should work together to clearly define the minimum requirements for assigning a diagnosis of HPV-related OPSCC in order to ensure consistent reporting of this emerging and increasingly prevalent disease.

Quantitative analysis of patient-specific dosimetric IMRT verification

International Nuclear Information System (INIS)

Budgell, G J; Perrin, B A; Mott, J H L; Fairfoul, J; Mackay, R I

2005-01-01

Patient-specific dosimetric verification methods for IMRT treatments are variable, time-consuming and frequently qualitative, preventing evidence-based reduction in the amount of verification performed. This paper addresses some of these issues by applying a quantitative analysis parameter to the dosimetric verification procedure. Film measurements in different planes were acquired for a series of ten IMRT prostate patients, analysed using the quantitative parameter, and compared to determine the most suitable verification plane. Film and ion chamber verification results for 61 patients were analysed to determine long-term accuracy, reproducibility and stability of the planning and delivery system. The reproducibility of the measurement and analysis system was also studied. The results show that verification results are strongly dependent on the plane chosen, with the coronal plane particularly insensitive to delivery error. Unexpectedly, no correlation could be found between the levels of error in different verification planes. Longer term verification results showed consistent patterns which suggest that the amount of patient-specific verification can be safely reduced, provided proper caution is exercised: an evidence-based model for such reduction is proposed. It is concluded that dose/distance to agreement (e.g., 3%/3 mm) should be used as a criterion of acceptability. Quantitative parameters calculated for a given criterion of acceptability should be adopted in conjunction with displays that show where discrepancies occur. Planning and delivery systems which cannot meet the required standards of accuracy, reproducibility and stability to reduce verification will not be accepted by the radiotherapy community

Patient-Specific Tailored Intervention Improves INR Time in Therapeutic Range and INR Variability in Heart Failure Patients.

Science.gov (United States)

Gotsman, Israel; Ezra, Orly; Hirsh Raccah, Bruria; Admon, Dan; Lotan, Chaim; Dekeyser Ganz, Freda

2017-08-01

Many patients with heart failure need anticoagulants, including warfarin. Good control is particularly challenging in heart failure patients, with range, thereby increasing the risk of complications. This study aimed to evaluate the effect of a patient-specific tailored intervention on anticoagulation control in patients with heart failure. Patients with heart failure taking warfarin therapy (n = 145) were randomized to either standard care or a 1-time intervention assessing potential risk factors for lability of INR, in which they received patient-specific instructions. Time in therapeutic range (TTR) using Rosendaal's linear model was assessed 3 months before and after the intervention. The patient-tailored intervention significantly increased anticoagulation control. The median TTR levels before intervention were suboptimal in the interventional and control groups (53% vs 45%, P = .14). After intervention the median TTR increased significantly in the interventional group compared with the control group (80% [interquartile range, 62%-93%] vs 44% [29%-61%], P <.0001). The intervention resulted in a significant improvement in the interventional group before versus after intervention (53% vs 80%, P <.0001) but not in the control group (45% vs 44%, P = .95). The percentage of patients with a TTR ≥60%, considered therapeutic, was substantially higher in the interventional group: 79% versus 25% (P <.0001). The INR variability (standard deviation of each patient's INR measurements) decreased significantly in the interventional group, from 0.53 to 0.32 (P <.0001) after intervention but not in the control group. Patient-specific tailored intervention significantly improves anticoagulation therapy in patients with heart failure. Copyright © 2017 Elsevier Inc. All rights reserved.

Skeletal Geometry and Indices of Bone Strength in Artistic Gymnasts

Science.gov (United States)

Dowthwaite, Jodi N.; Scerpella, Tamara A.

2010-01-01

This review addresses bone geometry and indices of skeletal strength associated with exposure to gymnastic loading during growth. A brief background characterizes artistic gymnastics as a mechanical loading model and outlines densitometric techniques, skeletal outcomes and challenges in assessment of skeletal adaptation. The literature on bone geometric adaptation to gymnastic loading is sparse and consists of results for disparate skeletal sites, maturity phases, gender compositions and assessment methods, complicating synthesis of an overriding view. Furthermore, most studies assess only females, with little information on males and adults. Nonetheless, gymnastic loading during growth appears to yield significant enlargement of total and cortical bone geometry (+10 to 30%) and elevation of trabecular density (+20%) in the forearm, yielding elevated indices of skeletal strength (+20 to +50%). Other sites exhibit more moderate geometric and densitometric adaptations (5 to 15%). Mode of adaptation appears to be site-specific; some sites demonstrate marked periosteal and endosteal expansion, whereas other sites exhibit negligible or moderate periosteal expansion coupled with endocortical contraction. Further research is necessary to address sex-, maturity- and bone tissue-specific adaptation, as well as maintenance of benefits beyond loading cessation. PMID:19949278

Second International workshop Geometry and Symbolic Computation

CERN Document Server

Walczak, Paweł; Geometry and its Applications

2014-01-01

This volume has been divided into two parts: Geometry and Applications. The geometry portion of the book relates primarily to geometric flows, laminations, integral formulae, geometry of vector fields on Lie groups, and osculation; the articles in the applications portion concern some particular problems of the theory of dynamical systems, including mathematical problems of liquid flows and a study of cycles for non-dynamical systems. This Work is based on the second international workshop entitled "Geometry and Symbolic Computations," held on May 15-18, 2013 at the University of Haifa and is dedicated to modeling (using symbolic calculations) in differential geometry and its applications in fields such as computer science, tomography, and mechanics. It is intended to create a forum for students and researchers in pure and applied geometry to promote discussion of modern state-of-the-art in geometric modeling using symbolic programs such as Maple™ and Mathematica®, as well as presentation of new results. ...

Comparison of left ventricular outflow geometry and aortic valve area in patients with aortic stenosis by 2-dimensional versus 3-dimensional echocardiography.

Science.gov (United States)

Saitoh, Takeji; Shiota, Maiko; Izumo, Masaki; Gurudevan, Swaminatha V; Tolstrup, Kirsten; Siegel, Robert J; Shiota, Takahiro

2012-06-01

The present study sought to elucidate the geometry of the left ventricular outflow tract (LVOT) in patients with aortic stenosis and its effect on the accuracy of the continuity equation-based aortic valve area (AVA) estimation. Real-time 3-dimensional transesophageal echocardiography (RT3D-TEE) provides high-resolution images of LVOT in patients with aortic stenosis. Thus, AVA is derived reliably with the continuity equation. Forty patients with aortic stenosis who underwent 2-dimensional transthoracic echocardiography (2D-TTE), 2-dimensional transesophageal echocardiography (2D-TEE), and RT3D-TEE were studied. In 2D-TTE and 2D-TEE, the LVOT areas were calculated as π × (LVOT dimension/2)(2). In RT3D-TEE, the LVOT areas and ellipticity ([diameter of the anteroposterior axis]/[diameter of the medial-lateral axis]) were evaluated by planimetry. The AVA is then determined using planimetry and the continuity equation method. LVOT shape was found to be elliptical (ellipticity of 0.80 ± 0.08). Accordingly, the LVOT areas measured by 2D-TTE (median 3.7 cm(2), interquartile range 3.1 to 4.1) and 2D-TEE (median 3.7 cm(2), interquartile range 3.1 to 4.0) were smaller than those by 3D-TEE (median 4.6 cm(2), interquartile range 3.9 to 5.3; p interquartile range 0.79 to 1.3, p interquartile range 0.64 to 0.94) and 2D-TEE (median 0.76 cm(2), interquartile range 0.62 to 0.95). Additionally, the continuity equation-based AVA by RT3D-TEE was consistent with the planimetry method. In conclusion, RT3D-TEE might allow more accurate evaluation of the elliptical LVOT geometry and continuity equation-based AVA in patients with aortic stenosis than 2D-TTE and 2D-TEE. Copyright © 2012 Elsevier Inc. All rights reserved.

Patient-related factors determining geometry of intracavitary applicators and pelvic dose distribution during cervical cancer brachytherapy

International Nuclear Information System (INIS)

Senkus-Konefka, Elzbieta; Kobierska, Anna; Jassem, Jacek; Badzio, Andrezej

1997-01-01

Purpose: The aim of this study was to assess retrospectively the influence of the size of cervical cancer brachytherapy applicators (ovoids and uterine tandems) on pelvic dose distribution and to analyze the impact of various patient-and disease-related factors on applicators' geometry and on dose distribution in particular applications. Methods and Materials: The subject of this study were 356 cervical cancer patients treated with Selectron LDR as a part of their radical radiotherapy. Analyzed factors included patient age, weight, number of vaginal deliveries, and disease stage. Results: The use of larger vaginal applicators resulted in lower bladder and rectum doses and in higher point B doses (all p < 0.0001); longer uterine tandems produced lower rectum doses and higher point B doses (both p < 0.0001). Increasing patient age and disease stage resulted in a decreased frequency of use of large ovoids (both p < 0.0001) and of long tandems (age: p = 0.0069, stage: p = 0.004). As a result, higher doses to bladder (age: p < 0.0001, stage: p = 0.017) and rectum (age: p = 0.037, stage: p = 0.011) were observed. Increasing age also resulted in lower point B doses (p < 0.0001). Increasing patient weight correlated with less frequent use of long tandems (p = 0.0015) and with higher bladder doses (p = 0.04). Higher number of vaginal deliveries was related to the increase in the use of long tandems (p = 0.002); in patients who had had at least one vaginal delivery, point B doses were significantly higher (p = 0.0059). In multivariate analysis ovoid size and uterine tandem length were dependent on patient age (respectively: p < 0.001 and p = 0.001), disease stage (respectively: p = 0.003 and p = 0.008) and on the number of vaginal deliveries (respectively: p = 0.07 and p 0.008). Doses to critical organs and to points B were dependent on patient age (respectively: p < 0.001, p = 0.011, and p < 0.001) and on disease stage (respectively: p < 0.001, p = 0.004, and p = 0

Disease-Specific Mortality of Differentiated Thyroid Cancer Patients in Korea: A Multicenter Cohort Study

Directory of Open Access Journals (Sweden)

Min Ji Jeon

2017-11-01

Full Text Available BackgroundLittle is known regarding disease-specific mortality of differentiated thyroid cancer (DTC patients and its risk factors in Korea.MethodsWe retrospectively reviewed a large multi-center cohort of thyroid cancer from six Korean hospitals and included 8,058 DTC patients who underwent initial surgery between 1996 and 2005.ResultsMean age of patients at diagnosis was 46.2±12.3 years; 87% were females. Most patients had papillary thyroid cancer (PTC; 97% and underwent total thyroidectomy (85%. Mean size of the primary tumor was 1.6±1.0 cm. Approximately 40% of patients had cervical lymph node (LN metastases and 1.3% had synchronous distant metastases. During 11.3 years of follow-up, 150 disease-specific mortalities (1.9% occurred; the 10-year disease-specific survival (DSS rate was 98%. According to the year of diagnosis, the number of disease-specific mortality was not different. However, the rate of disease-specific mortality decreased during the study period (from 7.7% to 0.7%. Older age (≥45 years at diagnosis, male, follicular thyroid cancer (FTC versus PTC, larger tumor size (>2 cm, presence of extrathyroidal extension (ETE, lateral cervical LN metastasis, distant metastasis and tumor node metastasis (TNM stage were independent risk factors of disease-specific mortality of DTC patients.ConclusionThe rate of disease-specific mortality of Korean DTC patients was 1.9%; the 10-year DSS rate was 98% during 1996 to 2005. Older age at diagnosis, male, FTC, larger tumor size, presence of ETE, lateral cervical LN metastasis, distant metastasis, and TNM stages were significant risk factors of disease-specific mortality of Korean DTC patients.

Network geometry with flavor: From complexity to quantum geometry

Science.gov (United States)

Bianconi, Ginestra; Rahmede, Christoph

2016-03-01

Network geometry is attracting increasing attention because it has a wide range of applications, ranging from data mining to routing protocols in the Internet. At the same time advances in the understanding of the geometrical properties of networks are essential for further progress in quantum gravity. In network geometry, simplicial complexes describing the interaction between two or more nodes play a special role. In fact these structures can be used to discretize a geometrical d -dimensional space, and for this reason they have already been widely used in quantum gravity. Here we introduce the network geometry with flavor s =-1 ,0 ,1 (NGF) describing simplicial complexes defined in arbitrary dimension d and evolving by a nonequilibrium dynamics. The NGF can generate discrete geometries of different natures, ranging from chains and higher-dimensional manifolds to scale-free networks with small-world properties, scale-free degree distribution, and nontrivial community structure. The NGF admits as limiting cases both the Bianconi-Barabási models for complex networks, the stochastic Apollonian network, and the recently introduced model for complex quantum network manifolds. The thermodynamic properties of NGF reveal that NGF obeys a generalized area law opening a new scenario for formulating its coarse-grained limit. The structure of NGF is strongly dependent on the dimensionality d . In d =1 NGFs grow complex networks for which the preferential attachment mechanism is necessary in order to obtain a scale-free degree distribution. Instead, for NGF with dimension d >1 it is not necessary to have an explicit preferential attachment rule to generate scale-free topologies. We also show that NGF admits a quantum mechanical description in terms of associated quantum network states. Quantum network states evolve by a Markovian dynamics and a quantum network state at time t encodes all possible NGF evolutions up to time t . Interestingly the NGF remains fully classical but

Patient specific 3D visualisation of human brain

African Journals Online (AJOL)

Nafiisah

development of powerful new 3D image analysis and visualization algorithms that ... The tool is aimed to provide facility to reconstruct patient-specific 3D ... In this paper we present a review of the ... medical diagnosis, procedures training, pre-operative planning, ..... Body: Handbook of Numerical Analysis, Elsevier, 2004.

Specifics of nursing care for a patient with nutritional stoma.

OpenAIRE

MUSILOVÁ, Klára

2017-01-01

Main goal of the thesis was to map out the specifics of nursing care for a patient with a nutritious stoma. Three research questions have been identified in connection to this goal. First research question was focused on mapping out the nursing care for a patient prior applying the nutritious stoma. Second research question was focusing on nursing care for a patient while the nutritious stoma is being applied, and the last third question researches the nursing care for a patient after applyin...

Psychiatric in-patients' experience of being secluded in a specific ...

African Journals Online (AJOL)

This qualitative, explorative, descriptive and contextual study was undertaken to explore and describe the experiences of psychiatric in-patients who are secluded in a specific hospital in Lesotho. Evidence about the rationale and appropriate use of seclusion as well as promotion of mental health in secluded patients has ...

The Persistification of the ATLAS Geometry

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00068562; The ATLAS collaboration; Bianchi, Riccardo-Maria

2016-01-01

The complex geometry of the whole detector of the ATLAS experiment at LHC is currently stored only in custom online databases, from which it is built on-the- y on request. Accessing the online geometry guarantees accessing the latest version of the detector description, but requires the setup of the full ATLAS so ware framework “Athena”, which provides the online services and the tools to retrieve the data from the database. is operation is cumbersome and slows down the applications that need to access the geometry. Moreover, all applications that need to access the detector geom- etry need to be built and run on the same platform as the ATLAS framework, preventing the usage of the actual detector geometry in stand-alone applications. Here we propose a new mechanism to persistify and serve the geometry of HEP experiments. e new mechanism is composed by a new le format and a REST API. e new le format allows to store the whole detector description locally in a at le, and it is especially optimized to descri...

Risks of all-cause and site-specific fractures among hospitalized patients with COPD

OpenAIRE

Liao, Kuang-Ming; Liang, Fu-Wen; Li, Chung-Yi

2016-01-01

Abstract Patients with chronic obstructive pulmonary disease (COPD) have a high prevalence of osteoporosis. The clinical sequel of osteoporosis is fracture. Patients with COPD who experience a fracture also have increased morbidity and mortality. Currently, the types of all-cause and site-specific fracture among patients with COPD are unknown. Thus, we elucidated the all-cause and site-specific fractures among patients with COPD. A retrospective, population-based, cohort study was conducted u...

Mechanical Loading during Growth Is Associated with Plane-specific Differences in Vertebral Geometry: A Cross-sectional Analysis Comparing Artistic Gymnasts vs. Non-gymnasts

Science.gov (United States)

Dowthwaite, Jodi N.; Rosenbaum, Paula F.; Scerpella, Tamara A.

2011-01-01

Lumbar spine geometry, density and indices of bone strength were assessed relative to menarche status, using artistic gymnastics exposure during growth as a model of mechanical loading. Paired posteroanterior (PA) and supine lateral (LAT) DXA scans of L3 for 114 females (60 ex/gymnasts and 54 non-gymnasts) yielded output for comparison of paired (PALAT) versus standard PA and LAT outcomes. BMC, areal BMD, vertebral body dimensions, bone mineral apparent density (BMAD), axial compressive strength (IBS) and a fracture risk index were evaluated, modeling vertebral body geometry as an ellipsoid cylinder. Two-factor ANCOVA tested statistical effects of gymnastic exposure, menarche status and their interaction, adjusting for age and height as appropriate. Compared to non-gymnasts, ex/gymnasts exhibited greater PABMD, PABMC, PAWIDTH, PA CROSS-SECTIONAL AREA (CSA), PAVOLUME, LATBMD, LATBMAD, PALATCSA and PALATIBS (p<0.05). Non-gymnasts exhibited greater LATDEPTH/PAWIDTH, LATBMC/PABMC, LATVHEIGHT, LATAREA and Fracture Risk Index. Using ellipsoid vertebral geometric models, no significant differences were detected for PA or PALAT BMAD. In contrast, cuboid model results (Carter 1992) suggested erroneous ex/gymnast PABMAD advantages, resulting from invalid assumptions of proportional variation in linear skeletal dimensions. Gymnastic exposure was associated with shorter, wider vertebral bodies, yielding greater axial compressive strength and lower fracture risk, despite no BMAD advantage. Our results suggest the importance of plane-specific vertebral geometric adaptation to mechanical loading during growth. Paired scan output provides a more accurate assessment of this adaptation than PA or LAT plane scans alone. PMID:21839871

Visualizing Three-dimensional Slab Geometries with ShowEarthModel

Science.gov (United States)

Chang, B.; Jadamec, M. A.; Fischer, K. M.; Kreylos, O.; Yikilmaz, M. B.

2017-12-01

Seismic data that characterize the morphology of modern subducted slabs on Earth suggest that a two-dimensional paradigm is no longer adequate to describe the subduction process. Here we demonstrate the effect of data exploration of three-dimensional (3D) global slab geometries with the open source program ShowEarthModel. ShowEarthModel was designed specifically to support data exploration, by focusing on interactivity and real-time response using the Vrui toolkit. Sixteen movies are presented that explore the 3D complexity of modern subduction zones on Earth. The first movie provides a guided tour through the Earth's major subduction zones, comparing the global slab geometry data sets of Gudmundsson and Sambridge (1998), Syracuse and Abers (2006), and Hayes et al. (2012). Fifteen regional movies explore the individual subduction zones and regions intersecting slabs, using the Hayes et al. (2012) slab geometry models where available and the Engdahl and Villasenor (2002) global earthquake data set. Viewing the subduction zones in this way provides an improved conceptualization of the 3D morphology within a given subduction zone as well as the 3D spatial relations between the intersecting slabs. This approach provides a powerful tool for rendering earth properties and broadening capabilities in both Earth Science research and education by allowing for whole earth visualization. The 3D characterization of global slab geometries is placed in the context of 3D slab-driven mantle flow and observations of shear wave splitting in subduction zones. These visualizations contribute to the paradigm shift from a 2D to 3D subduction framework by facilitating the conceptualization of the modern subduction system on Earth in 3D space.

Implosions and hypertoric geometry

DEFF Research Database (Denmark)

Dancer, A.; Kirwan, F.; Swann, A.

2013-01-01

The geometry of the universal hyperkahler implosion for SU (n) is explored. In particular, we show that the universal hyperkahler implosion naturally contains a hypertoric variety described in terms of quivers. Furthermore, we discuss a gauge theoretic approach to hyperkahler implosion.......The geometry of the universal hyperkahler implosion for SU (n) is explored. In particular, we show that the universal hyperkahler implosion naturally contains a hypertoric variety described in terms of quivers. Furthermore, we discuss a gauge theoretic approach to hyperkahler implosion....

Granular flows in constrained geometries

Science.gov (United States)

Murthy, Tejas; Viswanathan, Koushik

Confined geometries are widespread in granular processing applications. The deformation and flow fields in such a geometry, with non-trivial boundary conditions, determine the resultant mechanical properties of the material (local porosity, density, residual stresses etc.). We present experimental studies of deformation and plastic flow of a prototypical granular medium in different nontrivial geometries- flat-punch compression, Couette-shear flow and a rigid body sliding past a granular half-space. These geometries represent simplified scaled-down versions of common industrial configurations such as compaction and dredging. The corresponding granular flows show a rich variety of flow features, representing the entire gamut of material types, from elastic solids (beam buckling) to fluids (vortex-formation, boundary layers) and even plastically deforming metals (dead material zone, pile-up). The effect of changing particle-level properties (e.g., shape, size, density) on the observed flows is also explicitly demonstrated. Non-smooth contact dynamics particle simulations are shown to reproduce some of the observed flow features quantitatively. These results showcase some central challenges facing continuum-scale constitutive theories for dynamic granular flows.

Characterization of cat dander-specific T lymphocytes from atopic patients

NARCIS (Netherlands)

van Neerven, R. J.; van de Pol, M. M.; van Milligen, F. J.; Jansen, H. M.; Aalberse, R. C.; Kapsenberg, M. L.

1994-01-01

Fel d I, the major cat dander allergen, is recognized by serum IgE of more than 80% of all cat-allergic patients. Because IgE synthesis by B lymphocytes is under the control of T lymphocytes, we studied the specificity and lymphokine production profiles of cat dander-specific T lymphocytes.

Tolerance design of patient-specific range QA using the DMAIC framework in proton therapy.

Science.gov (United States)

Rah, Jeong-Eun; Shin, Dongho; Manger, Ryan P; Kim, Tae Hyun; Oh, Do Hoon; Kim, Dae Yong; Kim, Gwe-Ya

2018-02-01

To implement the DMAIC (Define-Measure-Analyze-Improve-Control) can be used for customizing the patient-specific QA by designing site-specific range tolerances. The DMAIC framework (process flow diagram, cause and effect, Pareto chart, control chart, and capability analysis) were utilized to determine the steps that need focus for improving the patient-specific QA. The patient-specific range QA plans were selected according to seven treatment site groups, a total of 1437 cases. The process capability index, C pm was used to guide the tolerance design of patient site-specific range. For prostate field, our results suggested that the patient range measurements were capable at the current tolerance level of ±1 mm in clinical proton plans. For other site-specific ranges, we analyzed that the tolerance tends to be overdesigned to insufficient process capability calculated by the patient-specific QA data. The customized tolerances were calculated for treatment sites. Control charts were constructed to simulate the patient QA time before and after the new tolerances were implemented. It is found that the total simulation QA time was decreased on average of approximately 20% after establishing new site-specific range tolerances. We simulated the financial impact of this project. The QA failure for whole process in proton therapy would lead up to approximately 30% increase in total cost. DMAIC framework can be used to provide an effective QA by setting customized tolerances. When tolerance design is customized, the quality is reasonably balanced with time and cost demands. © 2017 American Association of Physicists in Medicine.

A vector space approach to geometry

CERN Document Server

Hausner, Melvin

2010-01-01

The effects of geometry and linear algebra on each other receive close attention in this examination of geometry's correlation with other branches of math and science. In-depth discussions include a review of systematic geometric motivations in vector space theory and matrix theory; the use of the center of mass in geometry, with an introduction to barycentric coordinates; axiomatic development of determinants in a chapter dealing with area and volume; and a careful consideration of the particle problem. 1965 edition.

Integral geometry and valuations

CERN Document Server

Solanes, Gil

2014-01-01

Valuations are finitely additive functionals on the space of convex bodies. Their study has become a central subject in convexity theory, with fundamental applications to integral geometry. In the last years there has been significant progress in the theory of valuations, which in turn has led to important achievements in integral geometry. This book originated from two courses delivered by the authors at the CRM and provides a self-contained introduction to these topics, covering most of the recent advances. The first part, by Semyon Alesker, is devoted to the theory of convex valuations, with emphasis on the latest developments. A special focus is put on the new fundamental structures of the space of valuations discovered after Alesker's irreducibility theorem. Moreover, the author describes the newly developed theory of valuations on manifolds. In the second part, Joseph H. G. Fu gives a modern introduction to integral geometry in the sense of Blaschke and Santaló, based on the notions and tools presented...

CBM RICH geometry optimization

Energy Technology Data Exchange (ETDEWEB)

Mahmoud, Tariq; Hoehne, Claudia [II. Physikalisches Institut, Giessen Univ. (Germany); Collaboration: CBM-Collaboration

2016-07-01

The Compressed Baryonic Matter (CBM) experiment at the future FAIR complex will investigate the phase diagram of strongly interacting matter at high baryon density and moderate temperatures in A+A collisions from 2-11 AGeV (SIS100) beam energy. The main electron identification detector in the CBM experiment will be a RICH detector with a CO{sub 2} gaseous-radiator, focusing spherical glass mirrors, and MAPMT photo-detectors being placed on a PMT-plane. The RICH detector is located directly behind the CBM dipole magnet. As the final magnet geometry is now available, some changes in the RICH geometry become necessary. In order to guarantee a magnetic field of 1 mT at maximum in the PMT plane for effective operation of the MAPMTs, two measures have to be taken: The PMT plane is moved outwards of the stray field by tilting the mirrors by 10 degrees and shielding boxes have been designed. In this contribution the results of the geometry optimization procedure are presented.

Riemannian geometry

CERN Document Server

Petersen, Peter

2016-01-01

Intended for a one year course, this text serves as a single source, introducing readers to the important techniques and theorems, while also containing enough background on advanced topics to appeal to those students wishing to specialize in Riemannian geometry. This is one of the few Works to combine both the geometric parts of Riemannian geometry and the analytic aspects of the theory. The book will appeal to a readership that have a basic knowledge of standard manifold theory, including tensors, forms, and Lie groups. Important revisions to the third edition include: a substantial addition of unique and enriching exercises scattered throughout the text; inclusion of an increased number of coordinate calculations of connection and curvature; addition of general formulas for curvature on Lie Groups and submersions; integration of variational calculus into the text allowing for an early treatment of the Sphere theorem using a proof by Berger; incorporation of several recent results about manifolds with posit...

Kaehler geometry and SUSY mechanics

International Nuclear Information System (INIS)

Bellucci, Stefano; Nersessian, Armen

2001-01-01

We present two examples of SUSY mechanics related with Kaehler geometry. The first system is the N = 4 supersymmetric one-dimensional sigma-model proposed in hep-th/0101065. Another system is the N = 2 SUSY mechanics whose phase space is the external algebra of an arbitrary Kaehler manifold. The relation of these models with antisymplectic geometry is discussed

GPS: Geometry, Probability, and Statistics

Science.gov (United States)

Field, Mike

2012-01-01

It might be said that for most occupations there is now less of a need for mathematics than there was say fifty years ago. But, the author argues, geometry, probability, and statistics constitute essential knowledge for everyone. Maybe not the geometry of Euclid, but certainly geometrical ways of thinking that might enable us to describe the world…

Estimating patient-specific soft-tissue properties in a TKA knee.

Science.gov (United States)

Ewing, Joseph A; Kaufman, Michelle K; Hutter, Erin E; Granger, Jeffrey F; Beal, Matthew D; Piazza, Stephen J; Siston, Robert A

2016-03-01

Surgical technique is one factor that has been identified as critical to success of total knee arthroplasty. Researchers have shown that computer simulations can aid in determining how decisions in the operating room generally affect post-operative outcomes. However, to use simulations to make clinically relevant predictions about knee forces and motions for a specific total knee patient, patient-specific models are needed. This study introduces a methodology for estimating knee soft-tissue properties of an individual total knee patient. A custom surgical navigation system and stability device were used to measure the force-displacement relationship of the knee. Soft-tissue properties were estimated using a parameter optimization that matched simulated tibiofemoral kinematics with experimental tibiofemoral kinematics. Simulations using optimized ligament properties had an average root mean square error of 3.5° across all tests while simulations using generic ligament properties taken from literature had an average root mean square error of 8.4°. Specimens showed large variability among ligament properties regardless of similarities in prosthetic component alignment and measured knee laxity. These results demonstrate the importance of soft-tissue properties in determining knee stability, and suggest that to make clinically relevant predictions of post-operative knee motions and forces using computer simulations, patient-specific soft-tissue properties are needed. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

FINAL REPORT: GEOMETRY AND ELEMENTARY PARTICLE PHYSICS

Energy Technology Data Exchange (ETDEWEB)

Singer, Isadore M.

2008-03-04

The effect on mathematics of collaborations between high-energy theoretical physics and modern mathematics has been remarkable. Mirror symmetry has revolutionized enumerative geometry, and Seiberg-Witten invariants have greatly simplified the study of four manifolds. And because of their application to string theory, physicists now need to know cohomology theory, characteristic classes, index theory, K-theory, algebraic geometry, differential geometry, and non-commutative geometry. Much more is coming. We are experiencing a deeper contact between the two sciences, which will stimulate new mathematics essential to the physicists’ quest for the unification of quantum mechanics and relativity. Our grant, supported by the Department of Energy for twelve years, has been instrumental in promoting an effective interaction between geometry and string theory, by supporting the Mathematical Physics seminar, postdoc research, collaborations, graduate students and several research papers.

Final Report: Geometry And Elementary Particle Physics

International Nuclear Information System (INIS)

Singer, Isadore M.

2008-01-01

The effect on mathematics of collaborations between high-energy theoretical physics and modern mathematics has been remarkable. Mirror symmetry has revolutionized enumerative geometry, and Seiberg-Witten invariants have greatly simplified the study of four manifolds. And because of their application to string theory, physicists now need to know cohomology theory, characteristic classes, index theory, K-theory, algebraic geometry, differential geometry, and non-commutative geometry. Much more is coming. We are experiencing a deeper contact between the two sciences, which will stimulate new mathematics essential to the physicists quest for the unification of quantum mechanics and relativity. Our grant, supported by the Department of Energy for twelve years, has been instrumental in promoting an effective interaction between geometry and string theory, by supporting the Mathematical Physics seminar, postdoc research, collaborations, graduate students and several research papers.

Discrete quantum geometries and their effective dimension

International Nuclear Information System (INIS)

Thuerigen, Johannes

2015-01-01

In several approaches towards a quantum theory of gravity, such as group field theory and loop quantum gravity, quantum states and histories of the geometric degrees of freedom turn out to be based on discrete spacetime. The most pressing issue is then how the smooth geometries of general relativity, expressed in terms of suitable geometric observables, arise from such discrete quantum geometries in some semiclassical and continuum limit. In this thesis I tackle the question of suitable observables focusing on the effective dimension of discrete quantum geometries. For this purpose I give a purely combinatorial description of the discrete structures which these geometries have support on. As a side topic, this allows to present an extension of group field theory to cover the combinatorially larger kinematical state space of loop quantum gravity. Moreover, I introduce a discrete calculus for fields on such fundamentally discrete geometries with a particular focus on the Laplacian. This permits to define the effective-dimension observables for quantum geometries. Analysing various classes of quantum geometries, I find as a general result that the spectral dimension is more sensitive to the underlying combinatorial structure than to the details of the additional geometric data thereon. Semiclassical states in loop quantum gravity approximate the classical geometries they are peaking on rather well and there are no indications for stronger quantum effects. On the other hand, in the context of a more general model of states which are superposition over a large number of complexes, based on analytic solutions, there is a flow of the spectral dimension from the topological dimension d on low energy scales to a real number between 0 and d on high energy scales. In the particular case of 1 these results allow to understand the quantum geometry as effectively fractal.

Real time noninvasive assessment of external trunk geometry during surgical correction of adolescent idiopathic scoliosis

Directory of Open Access Journals (Sweden)

Mac-Thiong Jean-Marc

2009-02-01

Full Text Available Abstract Background The correction of trunk deformity is crucial in scoliosis surgery, especially for the patient's self-image. However, direct visualization of external scoliotic trunk deformity during surgical correction is difficult due to the covering draping sheets. Methods An optoelectronic camera system with 10 passive markers is used to track the trunk geometry of 5 scoliotic patients during corrective surgery. The position of 10 anatomical landmarks and 5 trunk indices computed from the position of the passive markers are compared during and after instrumentation of the spine. Results Internal validation of the accuracy of tracking was evaluated at 0.41 +/- 0.05 mm RMS. Intra operative tracking during surgical maneuvers shows improvement of the shoulder balance during and after correction of the spine. Improvement of the overall patient balance is observed. At last, a minor increase of the spinal length can be noticed. Conclusion Tracking of the external geometry of the trunk during surgical correction is useful to monitor changes occurring under the sterile draping sheets. Moreover, this technique can used be used to reach the optimal configuration on the operating frame before proceeding to surgery. The current tracking technique was able to detect significant changes in trunk geometry caused by posterior instrumentation of the spine despite significant correction of the spinal curvature. It could therefore become relevant for computer-assisted guidance of surgical maneuvers when performing posterior instrumentation of the scoliotic spine, provide important insights during positioning of patients.

An excursion through elementary mathematics, volume ii euclidean geometry

CERN Document Server

Caminha Muniz Neto, Antonio

2018-01-01

This book provides a comprehensive, in-depth overview of elementary mathematics as explored in Mathematical Olympiads around the world. It expands on topics usually encountered in high school and could even be used as preparation for a first-semester undergraduate course. This second volume covers Plane Geometry, Trigonometry, Space Geometry, Vectors in the Plane, Solids and much more. As part of a collection, the book differs from other publications in this field by not being a mere selection of questions or a set of tips and tricks that applies to specific problems. It starts from the most basic theoretical principles, without being either too general or too axiomatic. Examples and problems are discussed only if they are helpful as applications of the theory. Propositions are proved in detail and subsequently applied to Olympic problems or to other problems at the Olympic level. The book also explores some of the hardest problems presented at National and International Mathematics Olympiads, as well as many...

Effect of the kinetics of ammonium and nitrite oxidation on nitritation success or failure for different biofilm reactor geometries

DEFF Research Database (Denmark)

Lackner, Susanne; Smets, Barth F.

2012-01-01

was on the influence of key biokinetic parameters (maximum specific growth rates, oxygen and nitrogen affinity constants of AOB (ammonium oxidizing bacteria) and NOB (nitrite oxidizing bacteria)) and their ratios on nitritation efficiency in these geometries. This exhaustive simulation study revealed that nitritation...... strongly depends on the chosen kinetic parameters of AOB and NOB. The maximum specific growth rates (μmax,AOB and μmax,NOB) had the strongest impact on nitritation efficiency (NE). In comparison, the counter-diffusion geometry yielded more parameter combinations (27.5%) that resulted in high NE than the co...

Introduction into integral geometry and stereology

DEFF Research Database (Denmark)

Kiderlen, Markus

Statistics and Random Fields and is a self-containing introduction into integral geometry and its applications in stereology. The most important integral geometric tools for stereological applications are kinematic formulas and results of Blaschke-Petkantschin type. Therefore, Crofton's formula......This text is the extended version of two talks held at the Summer Academy Stochastic Geometry, Spatial Statistics and Random Fields in the Soellerhaus, Germany, in September 2009. It forms (with slight modifications) a chapter of the Springer lecture notes Lectures on Stochastic Geometry, Spatial...

Studies on transport phenomena in polymer solutions and suspensions flowing through tubes of tortuous wall geometry

Science.gov (United States)

Narayanan, C. M.

2014-02-01

Attempts have been made to analyse the momentum and heat transfer characteristics in tortuous flow of non-Newtonian fluids such as suspensions and polymer solutions through tubes of diverging-converging geometry. The results of the study indicate that the transfer coefficients are significantly higher in such systems as compared to the conventional couette flow (through uniform cylindrical tubes). Moreover, the simultaneous increase in pressure drop due to the tortuous wall geometry has been observed to be relatively insignificant. Fluids with different rheological characteristics such as Bingham plastic fluids, pseudoplastic fluids, Ellis model fluids and fluids obeying Reiner-Philippoff rheology have been studied. The specific advantages of these geometries in providing enhanced performance efficiency have been effectively highlighted.

External exposure model for various geometries of contaminated materials

International Nuclear Information System (INIS)

LePoire, D.; Kamboj, S.; Yu, C.

1996-01-01

A computational model for external exposure was developed for the U.S. Department of Energy's residual radioactive material guideline computer code (RESRAD) on the basis of dose coefficients from Federal Guidance Report No. 12 and the point-kernel method. This model includes the effects of different materials and exposure distances, as well as source geometry (cover thickness, source depth, area, and shape). A material factor is calculated on the basis of the point-kernel method using material-specific photon cross-section data and buildup factors. This present model was incorporated into RESRAD-RECYCLE (a RESRAD family code used for computing radiological impacts of metal recycling) and is being incorporated into RESRAD-BUILD (a DOE recommended code for computing impacts of building decontamination). The model was compared with calculations performed with the Monte Carlo N-Particle Code (MCNP) and the Microshield code for three different source geometries, three different radionuclides ( 234 U, 238 U, and 60 Co, representing low, medium, and high energy, respectively), and five different source materials (iron, copper, aluminum, water, and soil). The comparison shows that results of this model are in very good agreement with MCNP calculations (within 5% for 60 Co and within 30% for 238 U and 234 U for all materials and source geometries). Significant differences (greater than 100%) were observed with Microshield for thin 234 U sources

Computational biomechanics for medicine fundamental science and patient-specific applications

CERN Document Server

Miller, Karol; Wittek, Adam; Nielsen, Poul

2014-01-01

One of the greatest challenges facing the computational engineering community is to extend the success of computational mechanics to fields outside traditional engineering, in particular to biology, the biomedical sciences, and medicine. The Computational Biomechanics for Medicine titles provide an opportunity for specialists in computational biomechanics to present their latest methodologies and advancements. This latest installment comprises nine of the latest developments in both fundamental science and patient-specific applications, from researchers in Australia, New Zealand, USA, UK, France, Ireland, and China. Some of the interesting topics discussed are: cellular mechanics; tumor growth and modeling; medical image analysis; and both patient-specific fluid dynamics and solid mechanics simulations.

Frequency and specificity of red blood cell alloimmunization in chilean transfused patients.

Science.gov (United States)

Caamaño, José; Musante, Evangelina; Contreras, Margarita; Ulloa, Hernán; Reyes, Carolina; Inaipil, Verónica; Saavedra, Nicolás; Guzmán, Neftalí

2015-01-01

Alloimmunization is an adverse effect of blood transfusions. In Chile, alloimmunization frequency is not established, and for this reason the aim of this study was to investigate the prevalence and specificity of red blood cell (RBC) alloantibodies in Chilean transfused subjects. Records from 4,716 multi-transfused patients were analyzed. In these patients, antibody screening was carried out prior to cross-matching with a commercially available two-cell panel by the microcolum gel test, and samples with a positive screen were analyzed for the specificity of the alloantibody with a 16-cell identification panel. The incidence of RBC alloimmunization in transfused patients was 1.02% (48/4,716) with a higher prevalence in women (40/48). We detected 52 antibodies, the most frequent specificities identified were anti-E (30.8%), anti-K (26.9%), anti-D (7.7%), and anti-Fy(a) (5.8%). The highest incidence of alloantibodies was observed in cancer and gastroenterology patients. The data demonstrated a low alloimmunization frequency in Chilean transfused patients, principally associated with antibodies anti-E, anti-K, anti-D, and anti-Fy(a).

Specific efficacy expectations mediate exercise compliance in patients with COPD.

Science.gov (United States)

Kaplan, R M; Atkins, C J; Reinsch, S

1984-01-01

Social learning theory has generated two different approaches for the assessment of expectancies. Bandura argues that expectancies are specific and do not generalize. Therefore, he prefers measures of specific efficacy expectations. Others endorse the role of generalized expectancies measured by locus of control scales. The present study examines specific versus generalized expectancies as mediators of changes in exercise behavior among 60 older adult patients with Chronic Obstructive Pulmonary Disease. The patients were given a prescription to increase exercise and randomly assigned to experimental groups or control groups. All groups received attention but only experimental groups received training to increase their exercise. After 3 months, groups given specific training for compliance with walking significantly increased their activity in comparison to the control group receiving only attention. These changes were mediated by changes in perceived efficacy for walking, with efficacy expectations for other behaviors changing as a function of their similarity to walking. A generalized health locus of control expectancy measure was less clearly associated with behavior change. The results are interpreted as supporting Bandura's version of social theory.

A Patient-Specific Foot Model for the Estimate of Ankle Joint Forces in Patients with Juvenile Idiopathic Arthritis.

Science.gov (United States)

Prinold, Joe A I; Mazzà, Claudia; Di Marco, Roberto; Hannah, Iain; Malattia, Clara; Magni-Manzoni, Silvia; Petrarca, Maurizio; Ronchetti, Anna B; Tanturri de Horatio, Laura; van Dijkhuizen, E H Pieter; Wesarg, Stefan; Viceconti, Marco

2016-01-01

Juvenile idiopathic arthritis (JIA) is the leading cause of childhood disability from a musculoskeletal disorder. It generally affects large joints such as the knee and the ankle, often causing structural damage. Different factors contribute to the damage onset, including altered joint loading and other mechanical factors, associated with pain and inflammation. The prediction of patients' joint loading can hence be a valuable tool in understanding the disease mechanisms involved in structural damage progression. A number of lower-limb musculoskeletal models have been proposed to analyse the hip and knee joints, but juvenile models of the foot are still lacking. This paper presents a modelling pipeline that allows the creation of juvenile patient-specific models starting from lower limb kinematics and foot and ankle MRI data. This pipeline has been applied to data from three children with JIA and the importance of patient-specific parameters and modelling assumptions has been tested in a sensitivity analysis focused on the variation of the joint reaction forces. This analysis highlighted the criticality of patient-specific definition of the ankle joint axes and location of the Achilles tendon insertions. Patient-specific detection of the Tibialis Anterior, Tibialis Posterior, and Peroneus Longus origins and insertions were also shown to be important.

Surrogate Modeling for Geometry Optimization

DEFF Research Database (Denmark)

Rojas Larrazabal, Marielba de la Caridad; Abraham, Yonas; Holzwarth, Natalie

2009-01-01

A new approach for optimizing the nuclear geometry of an atomic system is described. Instead of the original expensive objective function (energy functional), a small number of simpler surrogates is used.......A new approach for optimizing the nuclear geometry of an atomic system is described. Instead of the original expensive objective function (energy functional), a small number of simpler surrogates is used....

Geometric control theory and sub-Riemannian geometry

CERN Document Server

Boscain, Ugo; Gauthier, Jean-Paul; Sarychev, Andrey; Sigalotti, Mario

2014-01-01

This volume presents recent advances in the interaction between Geometric Control Theory and sub-Riemannian geometry. On the one hand, Geometric Control Theory used the differential geometric and Lie algebraic language for studying controllability, motion planning, stabilizability and optimality for control systems. The geometric approach turned out to be fruitful in applications to robotics, vision modeling, mathematical physics etc. On the other hand, Riemannian geometry and its generalizations, such as  sub-Riemannian, Finslerian  geometry etc., have been actively adopting methods developed in the scope of geometric control. Application of these methods  has led to important results regarding geometry of sub-Riemannian spaces, regularity of sub-Riemannian distances, properties of the group  of diffeomorphisms of sub-Riemannian manifolds, local geometry and equivalence of distributions and sub-Riemannian structures, regularity of the Hausdorff volume.

Special metrics and group actions in geometry

CERN Document Server

Fino, Anna; Musso, Emilio; Podestà, Fabio; Vezzoni, Luigi

2017-01-01

The volume is a follow-up to the INdAM meeting “Special metrics and quaternionic geometry” held in Rome in November 2015. It offers a panoramic view of a selection of cutting-edge topics in differential geometry, including 4-manifolds, quaternionic and octonionic geometry, twistor spaces, harmonic maps, spinors, complex and conformal geometry, homogeneous spaces and nilmanifolds, special geometries in dimensions 5–8, gauge theory, symplectic and toric manifolds, exceptional holonomy and integrable systems. The workshop was held in honor of Simon Salamon, a leading international scholar at the forefront of academic research who has made significant contributions to all these subjects. The articles published here represent a compelling testimony to Salamon’s profound and longstanding impact on the mathematical community. Target readership includes graduate students and researchers working in Riemannian and complex geometry, Lie theory and mathematical physics.

On the optimization of low-cost FDM 3D printers for accurate replication of patient-specific abdominal aortic aneurysm geometry.

Science.gov (United States)

Chung, Michael; Radacsi, Norbert; Robert, Colin; McCarthy, Edward D; Callanan, Anthony; Conlisk, Noel; Hoskins, Peter R; Koutsos, Vasileios

2018-01-01

There is a potential for direct model manufacturing of abdominal aortic aneurysm (AAA) using 3D printing technique for generating flexible semi-transparent prototypes. A patient-specific AAA model was manufactured using fused deposition modelling (FDM) 3D printing technology. A flexible, semi-transparent thermoplastic polyurethane (TPU), called Cheetah Water (produced by Ninjatek, USA), was used as the flexible, transparent material for model manufacture with a hydrophilic support structure 3D printed with polyvinyl alcohol (PVA). Printing parameters were investigated to evaluate their effect on 3D-printing precision and transparency of the final model. ISO standard tear resistance tests were carried out on Ninjatek Cheetah specimens for a comparison of tear strength with silicone rubbers. It was found that an increase in printing speed decreased printing accuracy, whilst using an infill percentage of 100% and printing nozzle temperature of 255 °C produced the most transparent results. The model had fair transparency, allowing external inspection of model inserts such as stent grafts, and good flexibility with an overall discrepancy between CAD and physical model average wall thicknesses of 0.05 mm (2.5% thicker than the CAD model). The tear resistance test found Ninjatek Cheetah TPU to have an average tear resistance of 83 kN/m, higher than any of the silicone rubbers used in previous AAA model manufacture. The model had lower cost (4.50 GBP per model), shorter manufacturing time (25 h 3 min) and an acceptable level of accuracy (2.61% error) compared to other methods. It was concluded that the model would be of use in endovascular aneurysm repair planning and education, particularly for practicing placement of hooked or barbed stents, due to the model's balance of flexibility, transparency, robustness and cost-effectiveness.

Guide to Computational Geometry Processing

DEFF Research Database (Denmark)

Bærentzen, Jakob Andreas; Gravesen, Jens; Anton, François

be processed before it is useful. This Guide to Computational Geometry Processing reviews the algorithms for processing geometric data, with a practical focus on important techniques not covered by traditional courses on computer vision and computer graphics. This is balanced with an introduction...... to the theoretical and mathematical underpinnings of each technique, enabling the reader to not only implement a given method, but also to understand the ideas behind it, its limitations and its advantages. Topics and features: Presents an overview of the underlying mathematical theory, covering vector spaces......, metric space, affine spaces, differential geometry, and finite difference methods for derivatives and differential equations Reviews geometry representations, including polygonal meshes, splines, and subdivision surfaces Examines techniques for computing curvature from polygonal meshes Describes...

A Whirlwind Tour of Computational Geometry.

Science.gov (United States)

Graham, Ron; Yao, Frances

1990-01-01

Described is computational geometry which used concepts and results from classical geometry, topology, combinatorics, as well as standard algorithmic techniques such as sorting and searching, graph manipulations, and linear programing. Also included are special techniques and paradigms. (KR)

Monte Carlo simulation of fully Markovian stochastic geometries

International Nuclear Information System (INIS)

Lepage, Thibaut; Delaby, Lucie; Malvagi, Fausto; Mazzolo, Alain

2010-01-01

The interest in resolving the equation of transport in stochastic media has continued to increase these last years. For binary stochastic media it is often assumed that the geometry is Markovian, which is never the case in usual environments. In the present paper, based on rigorous mathematical theorems, we construct fully two-dimensional Markovian stochastic geometries and we study their main properties. In particular, we determine a percolation threshold p c , equal to 0.586 ± 0.0015 for such geometries. Finally, Monte Carlo simulations are performed through these geometries and the results compared to homogeneous geometries. (author)

Tidal stresses and energy gaps in microstate geometries

Science.gov (United States)

Tyukov, Alexander; Walker, Robert; Warner, Nicholas P.

2018-02-01

We compute energy gaps and study infalling massive geodesic probes in the new families of scaling, microstate geometries that have been constructed recently and for which the holographic duals are known. We find that in the deepest geometries, which have the lowest energy gaps, the geodesic deviation shows that the stress reaches the Planck scale long before the probe reaches the cap of the geometry. Such probes must therefore undergo a stringy transition as they fall into microstate geometry. We discuss the scales associated with this transition and comment on the implications for scrambling in microstate geometries.

VIII International Meeting on Lorentzian Geometry

CERN Document Server

Flores, José; Palomo, Francisco; GeLoMa 2016; Lorentzian geometry and related topics

2017-01-01

This volume contains a collection of research papers and useful surveys by experts in the field which provide a representative picture of the current status of this fascinating area. Based on contributions from the VIII International Meeting on Lorentzian Geometry, held at the University of Málaga, Spain, this volume covers topics such as distinguished (maximal, trapped, null, spacelike, constant mean curvature, umbilical...) submanifolds, causal completion of spacetimes, stationary regions and horizons in spacetimes, solitons in semi-Riemannian manifolds, relation between Lorentzian and Finslerian geometries and the oscillator spacetime. In the last decades Lorentzian geometry has experienced a significant impulse, which has transformed it from just a mathematical tool for general relativity to a consolidated branch of differential geometry, interesting in and of itself. Nowadays, this field provides a framework where many different mathematical techniques arise with applications to multiple parts of mathem...

Transformational plane geometry

CERN Document Server

Umble, Ronald N

2014-01-01

Axioms of Euclidean Plane Geometry The Existence and Incidence Postulates The Distance and Ruler Postulates The Plane Separation Postulate The Protractor Postulate The Side-Angle-Side Postulate and the Euclidean Parallel Postulate Theorems of Euclidean Plane Geometry The Exterior Angle Theorem Triangle Congruence Theorems The Alternate Interior Angles Theorem and the Angle Sum Theorem Similar Triangles Introduction to Transformations, Isometries, and Similarities Transformations Isometries and SimilaritiesAppendix: Proof of Surjectivity Translations, Rotations, and Reflections Translations Rotations Reflections Appendix: Geometer's Sketchpad Commands Required by Exploratory Activities Compositions of Translations, Rotations, and Reflections The Three Points Theorem Rotations as Compositions of Two Reflections Translations as Compositions of Two Halfturns or Two Reflections The Angle Addition Theorem Glide Reflections Classification of Isometries The Fundamental Theorem and Congruence Classification of Isometr...

Multilevel geometry optimization

Science.gov (United States)

Rodgers, Jocelyn M.; Fast, Patton L.; Truhlar, Donald G.

2000-02-01

Geometry optimization has been carried out for three test molecules using six multilevel electronic structure methods, in particular Gaussian-2, Gaussian-3, multicoefficient G2, multicoefficient G3, and two multicoefficient correlation methods based on correlation-consistent basis sets. In the Gaussian-2 and Gaussian-3 methods, various levels are added and subtracted with unit coefficients, whereas the multicoefficient Gaussian-x methods involve noninteger parameters as coefficients. The multilevel optimizations drop the average error in the geometry (averaged over the 18 cases) by a factor of about two when compared to the single most expensive component of a given multilevel calculation, and in all 18 cases the accuracy of the atomization energy for the three test molecules improves; with an average improvement of 16.7 kcal/mol.

Fractal geometry mathematical foundations and applications

CERN Document Server

Falconer, Kenneth

2013-01-01

The seminal text on fractal geometry for students and researchers: extensively revised and updated with new material, notes and references that reflect recent directions. Interest in fractal geometry continues to grow rapidly, both as a subject that is fascinating in its own right and as a concept that is central to many areas of mathematics, science and scientific research. Since its initial publication in 1990 Fractal Geometry: Mathematical Foundations and Applications has become a seminal text on the mathematics of fractals.  The book introduces and develops the general theory and applica

Patient specific actual size 3D printed models for patient education in glioma treatment: first experiences.

Science.gov (United States)

van de Belt, Tom H; Nijmeijer, Hugo; Grim, David; Engelen, Lucien Jlpg; Vreeken, Rinaldo; van Gelder, Marleen Mmj; Laan, Mark Ter

2018-06-02

Cancer patients need high quality information about the disease stage, treatment options and side effects. High quality information can also improve health literacy, shared decision-making and satisfaction. We created patient-specific 3D models of tumours including surrounding functional areas, and assessed what patients with glioma actually value (or fear) about these models when they are used to educate them about the relation between their tumour and specific brain parts, the surgical procedure, and risks. We carried out an explorative study with adult glioma patients, who underwent functional MRI and DTi as part of the pre-operative work-up. All participants received an actual size 3D model, printed based on fMRI and DTi imaging. Semi-structured interviews were held to identify facilitators and barriers for using the model, and perceived effects. A model was successfully created for all 11 participants. A total of 18 facilitators and 8 barriers were identified. The model improved patients' understanding about their situation, that it was easier to ask questions to their neurosurgeon based on their model and that it supported their decision about the preferred treatment. A perceived barrier for using the 3D model was that it could be emotionally confronting, particularly in an early phase of the disease process. Positive effects were related to psychological domains including coping, learning effects and communication. Patient-specific 3D models are promising and simple tools that could help patients with glioma to better understand their situation, treatment options and risks. They have the potential to improve shared decision-making. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Planning for Evolution in a Production Environment: Migration from a Legacy Geometry Code to an Abstract Geometry Modeling Language in STAR

Science.gov (United States)

Webb, Jason C.; Lauret, Jerome; Perevoztchikov, Victor

2012-12-01

Increasingly detailed descriptions of complex detector geometries are required for the simulation and analysis of today's high-energy and nuclear physics experiments. As new tools for the representation of geometry models become available during the course of an experiment, a fundamental challenge arises: how best to migrate from legacy geometry codes developed over many runs to the new technologies, such as the ROOT/TGeo [1] framework, without losing touch with years of development, tuning and validation. One approach, which has been discussed within the community for a number of years, is to represent the geometry model in a higher-level language independent of the concrete implementation of the geometry. The STAR experiment has used this approach to successfully migrate its legacy GEANT 3-era geometry to an Abstract geometry Modelling Language (AgML), which allows us to create both native GEANT 3 and ROOT/TGeo implementations. The language is supported by parsers and a C++ class library which enables the automated conversion of the original source code to AgML, supports export back to the original AgSTAR[5] representation, and creates the concrete ROOT/TGeo geometry implementation used by our track reconstruction software. In this paper we present our approach, design and experience and will demonstrate physical consistency between the original AgSTAR and new AgML geometry representations.

NOTE: Patient-specific planning for prevention of mechanical collisions during radiotherapy

Science.gov (United States)

Nioutsikou, Elena; Bedford, James L.; Webb, Steve

2003-11-01

A common unwanted difficulty in treatment planning, especially in non-coplanar radiotherapy set-ups, is the potential collision of the rotating gantry with the couch and/or the patient's body. A technique and computer program that detects these and signals avoidance of such beam directions is presented. The problem was approached using analytical geometry. The separate components within the treatment room have either been measured and modelled for an Elekta linear accelerator, or read out from a Pinnacle3 treatment planning system and are represented as an integer grid of points in three-dimensional (3D) space. The module is attached to the treatment planning system and can provide rejection or acceptance of unwanted beam directions in a plan. In contrast to previous work that has only used patient models, each individual patient's outlines are considered here in their actual treatment position inclusive of any immobilization device. The extremities of the patient superiorly and inferiorly to the scanned region are simulated by an expanded version of the RANDO phantom. In this way, 'potential' collisions can be detected in addition to the certain ones. Patient position is not a limiting factor for the accuracy of the collision detection anymore, as each set-up is always created around the isocentre. Maps of allowed and forbidden zones within the treatment suite have been created by running the code for all possible gantry and couch angles for three commonly arising cases: a head and neck plan utilizing a small stereotactic collimator, a prostate plan with multileaf collimators and an abdominal plan with the lead tray attached. In the last case, the 3D map permitted significantly fewer set-up combinations. Good agreement between prediction and experiment confirmed the capability of the program and introduces a promising add-on for treatment planning.

MIFT: GIFT Combinatorial Geometry Input to VCS Code

Science.gov (United States)

1977-03-01

r-w w-^ H ^ß0318is CQ BRL °RCUMr REPORT NO. 1967 —-S: ... MIFT: GIFT COMBINATORIAL GEOMETRY INPUT TO VCS CODE Albert E...TITLE (and Subtitle) MIFT: GIFT Combinatorial Geometry Input to VCS Code S. TYPE OF REPORT & PERIOD COVERED FINAL 6. PERFORMING ORG. REPORT NUMBER...Vehicle Code System (VCS) called MORSE was modified to accept the GIFT combinatorial geometry package. GIFT , as opposed to the geometry package

Spacer geometry and particle deposition in spiral wound membrane feed channels

KAUST Repository

Radu, A.I.

2014-11-01

Deposition of microspheres mimicking bacterial cells was studied experimentally and with a numerical model in feed spacer membrane channels, as used in spiral wound nanofiltration (NF) and reverse osmosis (RO) membrane systems. In-situ microscopic observations in membrane fouling simulators revealed formation of specific particle deposition patterns for different diamond and ladder feed spacer orientations. A three-dimensional numerical model combining fluid flow with a Lagrangian approach for particle trajectory calculations could describe very well the in-situ observations on particle deposition in flow cells. Feed spacer geometry, positioning and cross-flow velocity sensitively influenced the particle transport and deposition patterns. The deposition patterns were not influenced by permeate production. This combined experimental-modeling approach could be used for feed spacer geometry optimization studies for reduced (bio)fouling. © 2014 Elsevier Ltd.

SPECIFIC FEATURES OF ANESTHESIA IN PATIENTS WITH MYASTHENIA GRAVIS.

Science.gov (United States)

Spasojevic, Ivana; Hajdukovic, Danica; Komarcevic, Milena; Petrovic, Stanislava; Jovanovic, Jelena; Ciric, Aleksandra

2016-09-01

Myasthenia gravis is an autoimmune disease caused by antibodies leading to the destruction of nicotinic acetylcholine receptors on the neuromuscular junction. It is characterized by muscle weakness that gets aggravated with physical activity and improves at rest. Myasthenia Gravis Foundation of America made the clinical classification of Myasthenia gravis which is still in use today. "Tensilon test" is still the gold standard for the diagnosis of Myasthenia gravis. In addition to this test repeated muscular stimulation can be used as well as the analysis of specific autoantibodies. Treatment of Myasthenia Gravis. In conservative treatment of Mysthenia gravis anticholinesterases, immunosuppressants and plasmapheresis can be used. If conservative treatment does not lead to the desired remission, surgical treatment is indicated. The most accepted indication for thymectomy is the presence of thymoma with generalized form of Myasthenia gravis in adults. How to Distinguish Myasthenic From Cholinergic Crisis.'The following is important to make a difference between these two crises: knowledge of the events that preceded the crisis, the size of pupils as well as the presence of muscarinic signs and tensilon test. Specific Features of Anesthesia in Patients with Myasthienia Gravis. Mechanism of the disease development is the reason'for the increased sensitivity or resistance of these patients to certain types of drugs used in anesthesia. Protocol of Perioperative Anesthesia in Patients with Myasthenia Gravis. Based on 35 years of experience in the surgical treatment of patients with Myasthenia gravis anesthesiologists at the Department of Thoracic Surgery, Institute for Pulmonary Diseases of Vojvodina. made the protocol of anesthesia and perioperative treatment for these patients. Anesthesiologists may have to deal with a patient with myasthenia gravis in different types of surgical interventions. The protocol for anesthesia and perioperative management of these patients

Physical meaning of the optical reference geometry

International Nuclear Information System (INIS)

Abramowicz, M.A.

1990-09-01

I show that contrary to a popular misconception the optical reference geometry, introduced a few years ago as a formally possible metric of a 3-space corresponding to a static spacetime, is quite satisfactory also from the physical point of view. The optical reference geometry has a clear physical meaning, as it may be constructed experimentally by measuring light round travel time between static observers. Distances and directions in the optical reference geometry are more strongly connected to experiment than distances and directions in the widely used directly projected metric (discussed e.g. in Landau and Lifshitz textbook. In addition, the optical reference geometry is more natural and convenient than the directly projected one in application to dynamics. In the optical geometry dynamical behaviour of matter is described by concepts and formulae identical to those well known in Newtonian dynamics on a given two dimensional (curved) surface. (author). 22 refs

Patient geometry-driven information retrieval for IMRT treatment plan quality control

International Nuclear Information System (INIS)

Wu Binbin; Ricchetti, Francesco; Sanguineti, Giuseppe; Kazhdan, Misha; Simari, Patricio; Chuang Ming; Taylor, Russell; Jacques, Robert; McNutt, Todd

2009-01-01

Purpose: Intensity modulated radiation therapy (IMRT) treatment plan quality depends on the planner's level of experience and the amount of time the planner invests in developing the plan. Planners often unwittingly accept plans when further sparing of the organs at risk (OARs) is possible. The authors propose a method of IMRT treatment plan quality control that helps planners to evaluate the doses of the OARs upon completion of a new plan. Methods: It is achieved by comparing the geometric configurations of the OARs and targets of a new patient with those of prior patients, whose plans are maintained in a database. They introduce the concept of a shape relationship descriptor and, specifically, the overlap volume histogram (OVH) to describe the spatial configuration of an OAR with respect to a target. The OVH provides a way to infer the likely DVHs of the OARs by comparing the relative spatial configurations between patients. A database of prior patients is built to serve as an external reference. At the conclusion of a new plan, planners search through the database and identify related patients by comparing the OAR-target geometric relationships of the new patient with those of prior patients. The treatment plans of these related patients are retrieved from the database and guide planners in determining whether lower doses delivered to the OARs in the new plan are feasible. Results: Preliminary evaluation is promising. In this evaluation, they applied the analysis to the parotid DVHs of 32 prior head-and-neck patients, whose plans are maintained in a database. Each parotid was queried against the other 63 parotids to determine whether a lower dose was possible. The 17 parotids that promised the greatest reduction in D 50 (DVH dose at 50% volume) were flagged. These 17 parotids came from 13 patients. The method also indicated that the doses of the other nine parotids of the 13 patients could not be reduced, so they were included in the replanning process as

Treatment planning for image-guided neuro-vascular interventions using patient-specific 3D printed phantoms

Science.gov (United States)

Russ, M.; O'Hara, R.; Setlur Nagesh, S. V.; Mokin, M.; Jimenez, C.; Siddiqui, A.; Bednarek, D.; Rudin, S.; Ionita, C.

2015-03-01

Minimally invasive endovascular image-guided interventions (EIGIs) are the preferred procedures for treatment of a wide range of vascular disorders. Despite benefits including reduced trauma and recovery time, EIGIs have their own challenges. Remote catheter actuation and challenging anatomical morphology may lead to erroneous endovascular device selections, delays or even complications such as vessel injury. EIGI planning using 3D phantoms would allow interventionists to become familiarized with the patient vessel anatomy by first performing the planned treatment on a phantom under standard operating protocols. In this study the optimal workflow to obtain such phantoms from 3D data for interventionist to practice on prior to an actual procedure was investigated. Patientspecific phantoms and phantoms presenting a wide range of challenging geometries were created. Computed Tomographic Angiography (CTA) data was uploaded into a Vitrea 3D station which allows segmentation and resulting stereo-lithographic files to be exported. The files were uploaded using processing software where preloaded vessel structures were included to create a closed-flow vasculature having structural support. The final file was printed, cleaned, connected to a flow loop and placed in an angiographic room for EIGI practice. Various Circle of Willis and cardiac arterial geometries were used. The phantoms were tested for ischemic stroke treatment, distal catheter navigation, aneurysm stenting and cardiac imaging under angiographic guidance. This method should allow for adjustments to treatment plans to be made before the patient is actually in the procedure room and enabling reduced risk of peri-operative complications or delays.

Lossless Geometry Compression Through Changing 3D Coordinates into 1D

Directory of Open Access Journals (Sweden)

Yongkui Liu

2013-08-01

Full Text Available A method of lossless geometry compression on the coordinates of the vertexes for grid model is presented. First, the 3D coordinates are pre-processed to be transformed into a specific form. Then these 3D coordinates are changed into 1D data by making the three coordinates of a vertex represented by only a position number, which is made of a large integer. To minimize the integers, they are sorted and the differences between two adjacent vertexes are stored in a vertex table. In addition to the technique of geometry compression on coordinates, an improved method for storing the compressed topological data in a facet table is proposed to make the method more complete and efficient. The experimental results show that the proposed method has a better compression rate than the latest method of lossless geometry compression, the Isenburg-Lindstrom-Snoeyink method. The theoretical analysis and the experiment results also show that the important decompression time of the new method is short. Though the new method is explained in the case of a triangular grid, it can also be used in other forms of grid model.

Transformasi Geometri Rotasi Berbantuan Software Geogebra

Directory of Open Access Journals (Sweden)

Muhamad Hanafi

2018-02-01

Full Text Available Penelitian  ini bertujuan untuk membantu visualisasi dan menemukan konsep pada Transformasi geometri Rotasi di titik Pusat  dengan menggunakan software GeoGebra. Penelitian ini mengulas tentang Koordinat Kartesius dan Polar, dan selanjutntya Transformasi geometri Rotasi di titik Pusat .

Algebra, Geometry and Mathematical Physics Conference

CERN Document Server

Paal, Eugen; Silvestrov, Sergei; Stolin, Alexander

2014-01-01

This book collects the proceedings of the Algebra, Geometry and Mathematical Physics Conference, held at the University of Haute Alsace, France, October 2011. Organized in the four areas of algebra, geometry, dynamical symmetries and conservation laws and mathematical physics and applications, the book covers deformation theory and quantization; Hom-algebras and n-ary algebraic structures; Hopf algebra, integrable systems and related math structures; jet theory and Weil bundles; Lie theory and applications; non-commutative and Lie algebra and more. The papers explore the interplay between research in contemporary mathematics and physics concerned with generalizations of the main structures of Lie theory aimed at quantization, and discrete and non-commutative extensions of differential calculus and geometry, non-associative structures, actions of groups and semi-groups, non-commutative dynamics, non-commutative geometry and applications in physics and beyond. The book benefits a broad audience of researchers a...

Homological mirror symmetry and tropical geometry

CERN Document Server

Catanese, Fabrizio; Kontsevich, Maxim; Pantev, Tony; Soibelman, Yan; Zharkov, Ilia

2014-01-01

The relationship between Tropical Geometry and Mirror Symmetry goes back to the work of Kontsevich and Y. Soibelman (2000), who applied methods of non-archimedean geometry (in particular, tropical curves) to Homological Mirror Symmetry. In combination with the subsequent work of Mikhalkin on the “tropical” approach to Gromov-Witten theory, and the work of Gross and Siebert, Tropical Geometry has now become a powerful tool. Homological Mirror Symmetry is the area of mathematics concentrated around several categorical equivalences connecting symplectic and holomorphic (or algebraic) geometry. The central ideas first appeared in the work of Maxim Kontsevich (1993). Roughly speaking, the subject can be approached in two ways: either one uses Lagrangian torus fibrations of Calabi-Yau manifolds (the so-called Strominger-Yau-Zaslow picture, further developed by Kontsevich and Soibelman) or one uses Lefschetz fibrations of symplectic manifolds (suggested by Kontsevich and further developed by Seidel). Tropical Ge...

Tensorial spacetime geometries carrying predictive, interpretable and quantizable matter dynamics

International Nuclear Information System (INIS)

Rivera Hernandez, Sergio

2012-01-01

Which tensor fields G on a smooth manifold M can serve as a spacetime structure? In the first part of this thesis, it is found that only a severely restricted class of tensor fields can provide classical spacetime geometries, namely those that can carry predictive, interpretable and quantizable matter dynamics. The obvious dependence of this characterization of admissible tensorial spacetime geometries on specific matter is not a weakness, but rather presents an insight: it was Maxwell theory that justified Einstein to promote Lorentzian manifolds to the status of a spacetime geometry. Any matter that does not mimick the structure of Maxwell theory, will force us to choose another geometry on which the matter dynamics of interest are predictive, interpretable and quantizable. These three physical conditions on matter impose three corresponding algebraic conditions on the totally symmetric contravariant coefficient tensor field P that determines the principal symbol of the matter field equations in terms of the geometric tensor G: the tensor field P must be hyperbolic, time-orientable and energy-distinguishing. Remarkably, these physically necessary conditions on the geometry are mathematically already sufficient to realize all kinematical constructions familiar from Lorentzian geometry, for precisely the same structural reasons. This we were able to show employing a subtle interplay of convex analysis, the theory of partial differential equations and real algebraic geometry. In the second part of this thesis, we then explore general properties of any hyperbolic, time-orientable and energy-distinguishing tensorial geometry. Physically most important are the construction of freely falling non-rotating laboratories, the appearance of admissible modified dispersion relations to particular observers, and the identification of a mechanism that explains why massive particles that are faster than some massless particles can radiate off energy until they are slower than all

Tensorial spacetime geometries carrying predictive, interpretable and quantizable matter dynamics

Energy Technology Data Exchange (ETDEWEB)

Rivera Hernandez, Sergio

2012-02-15

Which tensor fields G on a smooth manifold M can serve as a spacetime structure? In the first part of this thesis, it is found that only a severely restricted class of tensor fields can provide classical spacetime geometries, namely those that can carry predictive, interpretable and quantizable matter dynamics. The obvious dependence of this characterization of admissible tensorial spacetime geometries on specific matter is not a weakness, but rather presents an insight: it was Maxwell theory that justified Einstein to promote Lorentzian manifolds to the status of a spacetime geometry. Any matter that does not mimick the structure of Maxwell theory, will force us to choose another geometry on which the matter dynamics of interest are predictive, interpretable and quantizable. These three physical conditions on matter impose three corresponding algebraic conditions on the totally symmetric contravariant coefficient tensor field P that determines the principal symbol of the matter field equations in terms of the geometric tensor G: the tensor field P must be hyperbolic, time-orientable and energy-distinguishing. Remarkably, these physically necessary conditions on the geometry are mathematically already sufficient to realize all kinematical constructions familiar from Lorentzian geometry, for precisely the same structural reasons. This we were able to show employing a subtle interplay of convex analysis, the theory of partial differential equations and real algebraic geometry. In the second part of this thesis, we then explore general properties of any hyperbolic, time-orientable and energy-distinguishing tensorial geometry. Physically most important are the construction of freely falling non-rotating laboratories, the appearance of admissible modified dispersion relations to particular observers, and the identification of a mechanism that explains why massive particles that are faster than some massless particles can radiate off energy until they are slower than all

Use of information technologies in teaching course "Analytical geometry" in higher schools on example of software "ANALYTICAL GEOMETRY"

OpenAIRE

V. B. Grigorieva

2009-01-01

In article are considered the methodical questions of using of computer technologies, for example, the software "Analytical geometry", in process of teaching course of analytical geometry in the higher school.

Variable geometry Darrieus wind machine

Science.gov (United States)

Pytlinski, J. T.; Serrano, D.

1983-08-01

A variable geometry Darrieus wind machine is proposed. The lower attachment of the blades to the rotor can move freely up and down the axle allowing the blades of change shape during rotation. Experimental data for a 17 m. diameter Darrieus rotor and a theoretical model for multiple streamtube performance prediction were used to develop a computer simulation program for studying parameters that affect the machine's performance. This new variable geometry concept is described and interrelated with multiple streamtube theory through aerodynamic parameters. The computer simulation study shows that governor behavior of a Darrieus turbine can not be attained by a standard turbine operating within normally occurring rotational velocity limits. A second generation variable geometry Darrieus wind turbine which uses a telescopic blade is proposed as a potential improvement on the studied concept.

Flux compactifications and generalized geometries

International Nuclear Information System (INIS)

Grana, Mariana

2006-01-01

Following the lectures given at CERN Winter School 2006, we present a pedagogical overview of flux compactifications and generalized geometries, concentrating on closed string fluxes in type II theories. We start by reviewing the supersymmetric flux configurations with maximally symmetric four-dimensional spaces. We then discuss the no-go theorems (and their evasion) for compactifications with fluxes. We analyse the resulting four-dimensional effective theories for Calabi-Yau and Calabi-Yau orientifold compactifications, concentrating on the flux-induced superpotentials. We discuss the generic mechanism of moduli stabilization and illustrate with two examples: the conifold in IIB and a T 6 /(Z 3 x Z 3 ) torus in IIA. We finish by studying the effective action and flux vacua for generalized geometries in the context of generalized complex geometry

Flux compactifications and generalized geometries

Energy Technology Data Exchange (ETDEWEB)

Grana, Mariana [Service de Physique Theorique, CEA/Saclay, 91191 Gif-sur-Yvette Cedex (France)

2006-11-07

Following the lectures given at CERN Winter School 2006, we present a pedagogical overview of flux compactifications and generalized geometries, concentrating on closed string fluxes in type II theories. We start by reviewing the supersymmetric flux configurations with maximally symmetric four-dimensional spaces. We then discuss the no-go theorems (and their evasion) for compactifications with fluxes. We analyse the resulting four-dimensional effective theories for Calabi-Yau and Calabi-Yau orientifold compactifications, concentrating on the flux-induced superpotentials. We discuss the generic mechanism of moduli stabilization and illustrate with two examples: the conifold in IIB and a T{sup 6} /(Z{sub 3} x Z{sub 3}) torus in IIA. We finish by studying the effective action and flux vacua for generalized geometries in the context of generalized complex geometry.

Virus-Specific T Cells for the Immunocompromised Patient

Directory of Open Access Journals (Sweden)

Amy Houghtelin

2017-10-01

Full Text Available While progress has been made in the treatment of both hematologic cancers and solid tumors, chemorefractory or relapsed disease often portends a dismal prognosis, and salvage chemotherapy or radiation expose patients to intolerable toxicities and may not be effective. Hematopoietic stem cell transplant offers the promise of cure for many patients, and while mismatched, unrelated or haploidentical donors are increasingly available, the recipients are at higher risk of severe immunosuppression and immune dysregulation due to graft versus host disease. Viral infections remain a primary cause of severe morbidity and mortality in this patient population. Again, many therapeutic options for viral disease are toxic, may be ineffective or generate resistance, or fail to convey long-term protection. Adoptive cell therapy with virus-specific T cells (VSTs is a targeted therapy that is efficacious and has minimal toxicity in immunocompromised patients with CMV and EBV infections in particular. Products have since been generated specific for multiple viral antigens (multi-VST, which are not only effective but also confer protection in 70–90% of recipients when used as prophylaxis. Notably, these products can be generated from either virus-naive or virus-experienced autologous or allogeneic sources, including partially matched HLA-matched third-party donors. Obstacles to effective VST treatment are donor availability and product generation time. Banking of third-party VST is an attractive way to overcome these constraints and provide products on an as-needed basis. Other developments include epitope discovery to broaden the number of viral antigens targets in a single product, the optimization of VST generation from naive donor sources, and the modification of VSTs to enhance persistence and efficacy in vivo.

Virus-Specific T Cells for the Immunocompromised Patient.

Science.gov (United States)

Houghtelin, Amy; Bollard, Catherine M

2017-01-01

While progress has been made in the treatment of both hematologic cancers and solid tumors, chemorefractory or relapsed disease often portends a dismal prognosis, and salvage chemotherapy or radiation expose patients to intolerable toxicities and may not be effective. Hematopoietic stem cell transplant offers the promise of cure for many patients, and while mismatched, unrelated or haploidentical donors are increasingly available, the recipients are at higher risk of severe immunosuppression and immune dysregulation due to graft versus host disease. Viral infections remain a primary cause of severe morbidity and mortality in this patient population. Again, many therapeutic options for viral disease are toxic, may be ineffective or generate resistance, or fail to convey long-term protection. Adoptive cell therapy with virus-specific T cells (VSTs) is a targeted therapy that is efficacious and has minimal toxicity in immunocompromised patients with CMV and EBV infections in particular. Products have since been generated specific for multiple viral antigens (multi-VST), which are not only effective but also confer protection in 70-90% of recipients when used as prophylaxis. Notably, these products can be generated from either virus-naive or virus-experienced autologous or allogeneic sources, including partially matched HLA-matched third-party donors. Obstacles to effective VST treatment are donor availability and product generation time. Banking of third-party VST is an attractive way to overcome these constraints and provide products on an as-needed basis. Other developments include epitope discovery to broaden the number of viral antigens targets in a single product, the optimization of VST generation from naive donor sources, and the modification of VSTs to enhance persistence and efficacy in vivo .

Geometry of Theory Space and RG Flows

Science.gov (United States)

Kar, Sayan

The space of couplings of a given theory is the arena of interest in this article. Equipped with a metric ansatz akin to the Fisher information matrix in the space of parameters in statistics (similar metrics in physics are the Zamolodchikov metric or the O'Connor-Stephens metric) we investigate the geometry of theory space through a study of specific examples. We then look into renormalisation group flows in theory space and make an attempt to characterise such flows via its isotropic expansion, rotation and shear. Consequences arising from the evolution equation for the isotropic expansion are discussed. We conclude by pointing out generalisations and pose some open questions.

Specificities of anti-neutrophil autoantibodies in patients with rheumatoid arthritis (RA)

DEFF Research Database (Denmark)

Brimnes, J; Halberg, P; Jacobsen, Søren

1997-01-01

The objective of this study was to characterize antigens recognized by neutrophil-specific autoantibodies from patients with RA. Sera from 62 RA patients were screened by indirect immunofluorescence (IIF). Positive sera were further tested by ELISAs for antibodies against various granule proteins...

Integrative Inferences on Pattern Geometries of Grapes Grown under Water Stress and Their Resulting Wines.

Science.gov (United States)

Hsieh, Fushing; Hsueh, Chih-Hsin; Heitkamp, Constantin; Matthews, Mark

2016-01-01

Multiple datasets of two consecutive vintages of replicated grape and wines from six different deficit irrigation regimes are characterized and compared. The process consists of four temporal-ordered signature phases: harvest field data, juice composition, wine composition before bottling and bottled wine. A new computing paradigm and an integrative inferential platform are developed for discovering phase-to-phase pattern geometries for such characterization and comparison purposes. Each phase is manifested by a distinct set of features, which are measurable upon phase-specific entities subject to the common set of irrigation regimes. Throughout the four phases, this compilation of data from irrigation regimes with subsamples is termed a space of media-nodes, on which measurements of phase-specific features were recoded. All of these collectively constitute a bipartite network of data, which is then normalized and binary coded. For these serial bipartite networks, we first quantify patterns that characterize individual phases by means of a new computing paradigm called "Data Mechanics". This computational technique extracts a coupling geometry which captures and reveals interacting dependence among and between media-nodes and feature-nodes in forms of hierarchical block sub-matrices. As one of the principal discoveries, the holistic year-factor persistently surfaces as the most inferential factor in classifying all media-nodes throughout all phases. This could be deemed either surprising in its over-arching dominance or obvious based on popular belief. We formulate and test pattern-based hypotheses that confirm such fundamental patterns. We also attempt to elucidate the driving force underlying the phase-evolution in winemaking via a newly developed partial coupling geometry, which is designed to integrate two coupling geometries. Such partial coupling geometries are confirmed to bear causal and predictive implications. All pattern inferences are performed with

Curvature tensor copies in affine geometry

International Nuclear Information System (INIS)

Srivastava, P.P.

1981-01-01

The sets of space-time and spin-connections which give rise to the same curvature tensor are constructed. The corresponding geometries are compared. Results are illustrated by an explicit calculation and comment on the copies in Einstein-Cartan and Weyl-Cartan geometries. (Author) [pt

Poisson geometry from a Dirac perspective

Science.gov (United States)

Meinrenken, Eckhard

2018-03-01

We present proofs of classical results in Poisson geometry using techniques from Dirac geometry. This article is based on mini-courses at the Poisson summer school in Geneva, June 2016, and at the workshop Quantum Groups and Gravity at the University of Waterloo, April 2016.

Development of the geometry database for the CBM experiment

Science.gov (United States)

Akishina, E. P.; Alexandrov, E. I.; Alexandrov, I. N.; Filozova, I. A.; Friese, V.; Ivanov, V. V.

2018-01-01

The paper describes the current state of the Geometry Database (Geometry DB) for the CBM experiment. The main purpose of this database is to provide convenient tools for: (1) managing the geometry modules; (2) assembling various versions of the CBM setup as a combination of geometry modules and additional files. The CBM users of the Geometry DB may use both GUI (Graphical User Interface) and API (Application Programming Interface) tools for working with it.

SABRINA, Geometry Plot Program for MCNP

International Nuclear Information System (INIS)

SEIDL, Marcus

2003-01-01

1 - Description of program or function: SABRINA is an interactive, three-dimensional, geometry-modeling code system, primarily for use with CCC-200/MCNP. SABRINA's capabilities include creation, visualization, and verification of three-dimensional geometries specified by either surface- or body-base combinatorial geometry; display of particle tracks are calculated by MCNP; and volume fraction generation. 2 - Method of solution: Rendering is performed by ray tracing or an edge and intersection algorithm. Volume fraction calculations are made by ray tracing. 3 - Restrictions on the complexity of the problem: A graphics display with X Window capability is required

Differential geometry and topology of curves

CERN Document Server

Animov, Yu

2001-01-01

Differential geometry is an actively developing area of modern mathematics. This volume presents a classical approach to the general topics of the geometry of curves, including the theory of curves in n-dimensional Euclidean space. The author investigates problems for special classes of curves and gives the working method used to obtain the conditions for closed polygonal curves. The proof of the Bakel-Werner theorem in conditions of boundedness for curves with periodic curvature and torsion is also presented. This volume also highlights the contributions made by great geometers. past and present, to differential geometry and the topology of curves.

The situation-specific theory of pain experience for Asian American cancer patients.

Science.gov (United States)

Im, Eun-Ok

2008-01-01

Studies have indicated the need for theories that explain and target ethnic-specific cancer pain experiences, including those of Asian Americans. In this article, I present a situation-specific theory that explains the unique cancer pain experience of Asian Americans. Unlike other existing theories, this situation-specific theory was developed on the basis of evidence, including a systematic literature review and research findings, making it comprehensive and highly applicable to research and practice with Asian American patients with cancer. Thus, this theory would strengthen the interconnections among theory, evidence, and practice in pain management for Asian American cancer patients.

Geometry of surfaces a practical guide for mechanical engineers

CERN Document Server

Radzevich, Stephen P

2012-01-01

Presents an in-depth analysis of geometry of part surfaces and provides the tools for solving complex engineering problems Geometry of Surfaces: A Practical Guide for Mechanical Engineers is a comprehensive guide to applied geometry of surfaces with focus on practical applications in various areas of mechanical engineering. The book is divided into three parts on Part Surfaces, Geometry of Contact of Part Surfaces and Mapping of the Contacting Part Surfaces. Geometry of Surfaces: A Practical Guide for Mechanical Engineers combines differential geometry and gearing theory and presents new developments in the elementary theory of enveloping surfaces. Written by a leading expert of the field, this book also provides the reader with the tools for solving complex engineering problems in the field of mechanical engineering. Presents an in-depth analysis of geometry of part surfaces Provides tools for solving complex engineering problems in the field of mechanical engineering Combines differential geometry an...

Axial‐type olivine crystallographic preferred orientations: the effect of strain geometry on mantle texture

NARCIS (Netherlands)

Chatzaras, V.; Kruckenberg, Seth C.; Cohen, Shaina M.; Medaris Jr., L. Gordon; Withers, Anthony C.; Bagley, Brian

The effect of finite strain geometry on crystallographic preferred orientation (CPO) is poorly constrained in the upper mantle. Specifically, the relationship between shape preferred orientation (SPO) and CPO in the mantle rocks remains unclear. We analyzed a suite of 40 spinel peridotite xenoliths

[Specific iatrogenic risks to patients with HIV infection].

Science.gov (United States)

De Tournemire, R; Yeni, P

1994-01-01

Human immunodeficiency virus-infected patients are exposed to more or less specific iatrogenic diseases. The main characteristics of the risks encountered in this field are described: drug intolerance, mostly to sulfamethoxazole-trimethoprim, is extremely frequent; nucleoside analogue antiviral toxicity is reminiscent of that of chemotherapy; nosocomial infections, in general, are more prominent than in HIV-non infected patients. Intravenous line infections are particularly frequent, but these devices are necessary for prolonged intravenous therapies such as anti-CMV treatment of parenteral nutrition. An improved understanding of different etiopathogenic mechanisms and a better approach of the toxicity/efficacy ratio for each treatment would allow to reduce the excessive morbidity due to iatrogenicity.

Left Ventricular Geometry and Blood Pressure as Predictors of Adverse Progression of Fabry Cardiomyopathy.

Science.gov (United States)

Krämer, Johannes; Bijnens, Bart; Störk, Stefan; Ritter, Christian O; Liu, Dan; Ertl, Georg; Wanner, Christoph; Weidemann, Frank

2015-01-01

In spite of several research studies help to describe the heart in Fabry disease (FD), the cardiomyopathy is not entirely understood. In addition, the impact of blood pressure and alterations in geometry have not been systematically evaluated. In 74 FD patients (mean age 36±12 years; 45 females) the extent of myocardial fibrosis and its progression were quantified using cardiac magnetic-resonance-imaging with late enhancement technique (LE). Results were compared to standard echocardiography complemented by 2D-speckle-tracking, 3D-sphericity-index (SI) and standardized blood pressure measurement. At baseline, no patient received enzyme replacement therapy (ERT). After 51±24 months, a follow-up examination was performed. Systolic blood pressure (SBP) was higher in patients with vs. without LE: 123±17 mmHg vs. 115±13 mmHg; P = 0.04. A positive correlation was found between SI and the amount of LE-positive myocardium (r = 0.51; PAUC = 0.785; P<0.05). LV geometry as assessed by the sphericity index is altered in relation to the stage of the Fabry cardiomyopathy. Although patients with FD are not hypertensive, the SBP has a clear impact on the progression of the cardiomyopathy.

Multilevel geometry optimization

Energy Technology Data Exchange (ETDEWEB)

Rodgers, Jocelyn M. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States); Fast, Patton L. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States); Truhlar, Donald G. [Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States)

2000-02-15

Geometry optimization has been carried out for three test molecules using six multilevel electronic structure methods, in particular Gaussian-2, Gaussian-3, multicoefficient G2, multicoefficient G3, and two multicoefficient correlation methods based on correlation-consistent basis sets. In the Gaussian-2 and Gaussian-3 methods, various levels are added and subtracted with unit coefficients, whereas the multicoefficient Gaussian-x methods involve noninteger parameters as coefficients. The multilevel optimizations drop the average error in the geometry (averaged over the 18 cases) by a factor of about two when compared to the single most expensive component of a given multilevel calculation, and in all 18 cases the accuracy of the atomization energy for the three test molecules improves; with an average improvement of 16.7 kcal/mol. (c) 2000 American Institute of Physics.

Machine learning spatial geometry from entanglement features

Science.gov (United States)

You, Yi-Zhuang; Yang, Zhao; Qi, Xiao-Liang

2018-02-01

Motivated by the close relations of the renormalization group with both the holography duality and the deep learning, we propose that the holographic geometry can emerge from deep learning the entanglement feature of a quantum many-body state. We develop a concrete algorithm, call the entanglement feature learning (EFL), based on the random tensor network (RTN) model for the tensor network holography. We show that each RTN can be mapped to a Boltzmann machine, trained by the entanglement entropies over all subregions of a given quantum many-body state. The goal is to construct the optimal RTN that best reproduce the entanglement feature. The RTN geometry can then be interpreted as the emergent holographic geometry. We demonstrate the EFL algorithm on a 1D free fermion system and observe the emergence of the hyperbolic geometry (AdS3 spatial geometry) as we tune the fermion system towards the gapless critical point (CFT2 point).

GEOMETRY – AN IMPORTANT MEANS OF EDUCATION IN THE CIVILISATION SCOPE

OpenAIRE

Liliana TOCARIU, PhD

2017-01-01

Geometry (from the Greek: γεωμετρία; geo = earth, metria = measure) is a genuine science, rooted in mathematics, which studies the plane and spatial forms of bodies from the objective or conceptual reality and the nature of the relationship that exists between them. Due to its complexity, geometry is divided into: Euclidian geometry, analytical geometry, descriptive geometry, projective geometry, kinematic geometry, surface and curve differential geometry, axiomatic geometry,...

Prediagnostic prostate-specific antigen kinetics and the risk of biopsy progression in active surveillance patients.

Science.gov (United States)

Iremashvili, Viacheslav; Barney, Shane L; Manoharan, Murugesan; Kava, Bruce R; Parekh, Dipen J; Punnen, Sanoj

2016-04-01

To analyze the association between prediagnostic prostate-specific antigen kinetics and the risk of biopsy progression in prostate cancer patients on active surveillance, and to study the effect of prediagnostic prostate-specific antigen values on the predictive performance of prostate-specific antigen velocity and prostate-specific antigen doubling time. The study included 137 active surveillance patients with two or more prediagnostic prostate-specific antigen levels measured over a period of at least 3 months. Two sets of analyses were carried out. First, the association between prostate-specific antigen kinetics calculated using only the prediagnostic prostate-specific antigen values and the risk of biopsy progression was studied. Second, using the same cohort of patients, the predictive value of prostate-specific antigen kinetics calculated using only post-diagnostic prostate-specific antigens and compared with that of prostate-specific antigen kinetics based on both pre- and post-diagnostic prostate-specific antigen levels was analyzed. Of 137 patients included in the analysis, 37 (27%) had biopsy progression over a median follow-up period of 3.2 years. Prediagnostic prostate-specific antigen velocity of more than 2 ng/mL/year and 3 ng/mL/year was statistically significantly associated with the risk of future biopsy progression. However, after adjustment for baseline prostate-specific antigen density, these associations were no longer significant. None of the tested prostate-specific antigen kinetics based on combined pre- and post-diagnostic prostate-specific antigen values were statistically significantly associated with the risk of biopsy progression. Historical prediagnostic prostate-specific antigens seems to be not clinically useful in patients diagnosed with low-risk prostate cancer on active surveillance. © 2016 The Japanese Urological Association.

Effects of Intraluminal Thrombus on Patient-Specific Abdominal Aortic Aneurysm Hemodynamics via Stereoscopic Particle Image Velocity and Computational Fluid Dynamics Modeling

Science.gov (United States)

Chen, Chia-Yuan; Antón, Raúl; Hung, Ming-yang; Menon, Prahlad; Finol, Ender A.; Pekkan, Kerem

2014-01-01

The pathology of the human abdominal aortic aneurysm (AAA) and its relationship to the later complication of intraluminal thrombus (ILT) formation remains unclear. The hemodynamics in the diseased abdominal aorta are hypothesized to be a key contributor to the formation and growth of ILT. The objective of this investigation is to establish a reliable 3D flow visualization method with corresponding validation tests with high confidence in order to provide insight into the basic hemodynamic features for a better understanding of hemodynamics in AAA pathology and seek potential treatment for AAA diseases. A stereoscopic particle image velocity (PIV) experiment was conducted using transparent patient-specific experimental AAA models (with and without ILT) at three axial planes. Results show that before ILT formation, a 3D vortex was generated in the AAA phantom. This geometry-related vortex was not observed after the formation of ILT, indicating its possible role in the subsequent appearance of ILT in this patient. It may indicate that a longer residence time of recirculated blood flow in the aortic lumen due to this vortex caused sufficient shear-induced platelet activation to develop ILT and maintain uniform flow conditions. Additionally, two computational fluid dynamics (CFD) modeling codes (Fluent and an in-house cardiovascular CFD code) were compared with the two-dimensional, three-component velocity stereoscopic PIV data. Results showed that correlation coefficients of the out-of-plane velocity data between PIV and both CFD methods are greater than 0.85, demonstrating good quantitative agreement. The stereoscopic PIV study can be utilized as test case templates for ongoing efforts in cardiovascular CFD solver development. Likewise, it is envisaged that the patient-specific data may provide a benchmark for further studying hemodynamics of actual AAA, ILT, and their convolution effects under physiological conditions for clinical applications. PMID:24316984

Numerical simulation of magnetic nano drug targeting in a patient-specific coeliac trunk

International Nuclear Information System (INIS)

Boghi, Andrea; Russo, Flavia; Gori, Fabio

2017-01-01

Highlights: • A mathematical model, describing magnetic nanoparticles in blood flow is proposed. • The model has been validated against MHD channel flow analytical solutions. • Four simulations have been carried out to study the parameters sensitivity. • The results show the limits of magnetic drug delivery applied to hepatic tumor. • Three parameters are deemed responsible for the low performances of the technique. - Abstract: Magnetic nano drug targeting, through the use of an external magnetic field, is a new technique for the treatment of several diseases, which can potentially avoid the dispersion of drugs in undesired locations of the body. Nevertheless, due to the limitations on the intensity of the magnetic field applied, the hydrodynamic forces can reduce the effectiveness of the procedure. This technique is studied in this paper with the Computational Fluid Dynamics (CFD), focusing on the influence of the magnetic probe position, and the direction of the circulating electric current. A single rectangular coil is used to generate the external magnetic field. A patient-specific geometry of the coeliac trunk is reconstructed from DICOM images, with the use of VMTK. A new solver, coupling the Lagrangian dynamics of the nanoparticles with the Eulerian dynamics of the blood, is implemented in OpenFOAM to perform the simulations. The resistive pressure, the Womersley’s profile for the inlet velocity and the magnetic field of a rectangular coil are implemented in the software as boundary conditions. The results show the influence of the position of the probe, as well as the limitations associated with the rectangular coil configuration.

Numerical simulation of magnetic nano drug targeting in a patient-specific coeliac trunk

Energy Technology Data Exchange (ETDEWEB)

Boghi, Andrea, E-mail: a.boghi@cranfield.ac.uk [School of Water, Energy and Environment, Cranfield University, Cranfield, Bedfordshire MK43 0AL (United Kingdom); Russo, Flavia; Gori, Fabio [Department of Mechanical Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome (Italy)

2017-09-01

Highlights: • A mathematical model, describing magnetic nanoparticles in blood flow is proposed. • The model has been validated against MHD channel flow analytical solutions. • Four simulations have been carried out to study the parameters sensitivity. • The results show the limits of magnetic drug delivery applied to hepatic tumor. • Three parameters are deemed responsible for the low performances of the technique. - Abstract: Magnetic nano drug targeting, through the use of an external magnetic field, is a new technique for the treatment of several diseases, which can potentially avoid the dispersion of drugs in undesired locations of the body. Nevertheless, due to the limitations on the intensity of the magnetic field applied, the hydrodynamic forces can reduce the effectiveness of the procedure. This technique is studied in this paper with the Computational Fluid Dynamics (CFD), focusing on the influence of the magnetic probe position, and the direction of the circulating electric current. A single rectangular coil is used to generate the external magnetic field. A patient-specific geometry of the coeliac trunk is reconstructed from DICOM images, with the use of VMTK. A new solver, coupling the Lagrangian dynamics of the nanoparticles with the Eulerian dynamics of the blood, is implemented in OpenFOAM to perform the simulations. The resistive pressure, the Womersley’s profile for the inlet velocity and the magnetic field of a rectangular coil are implemented in the software as boundary conditions. The results show the influence of the position of the probe, as well as the limitations associated with the rectangular coil configuration.

SU-E-I-12: Flexible Geometry Computed Tomography

Energy Technology Data Exchange (ETDEWEB)

Shaw, R [East Lansing, MI (United States)

2015-06-15

Purpose: The concept separates the mechanical connection between the radiation source and detector. This design allows the trajectory and orientation of the radiation source/detector to be customized to the object that is being imaged. This is in contrast to the formulaic rotation-translation image acquisition of conventional computed tomography(CT).Background/significance:CT devices that image a full range of: anatomy, patient populations, and imaging procedures are large. The root cause of the expanding size of comprehensive CT is due to the commitment to helical geometry that is hardwired into the image reconstruction. FGCT extends the application of alternative reconstruction techniques, i.e. tomosynthesis, by separating the two main components— radiation source and detector— and allow for 6 degrees of freedom motion for radiation source, detector, or both. The image acquisition geometry is then tailored to how the patient/object is positioned. This provides greater flexibility on the position and location that the patient/object is being imaged. Additionally, removing the need of a rotating gantry reduces the footprint so that CT is more mobile and more available to move to where the patient/object is at, instead of the other way around. Methods: As proof-of-principle, a reconstruction algorithm is designed to produce FGCT images. Using simulated detector data, voxels intersecting a line drawn between the radiation source and an individual detector are traced and modified using the detector signal. The detector signal is modified to compensate for changes in the source to detector distance. Adjacent voxels are modified in proportion to the detector signal, providing a simple image filter. Results: Image-quality from the proposed FGCT reconstruction technique is proving to be a challenge, producing hardily recognizable images from limited projections angles. Conclusion: Preliminary assessment of the reconstruction technique demonstrates the inevitable

Random geometry and Yang-Mills theory

International Nuclear Information System (INIS)

Froehlich, J.

1981-01-01

The author states various problems and discusses a very few preliminary rigorous results in a branch of mathematics and mathematical physics which one might call random (or stochastic) geometry. Furthermore, he points out why random geometry is important in the quantization of Yang-Mills theory. (Auth.)

Quantification of variability in bedform geometry

NARCIS (Netherlands)

van der Mark, C.F.; Blom, Astrid; Hulscher, Suzanne J.M.H.

2008-01-01

We analyze the variability in bedform geometry in laboratory and field studies. Even under controlled steady flow conditions in laboratory flumes, bedforms are irregular in size, shape, and spacing, also in case of well-sorted sediment. Our purpose is to quantify the variability in bedform geometry.

Initial stress and nonlinear material behavior in patient-specific AAA wall stress analysis

NARCIS (Netherlands)

Speelman, L.; Bosboom, E.M.H.; Schurink, G.W.H.; Buth, J.; Breeuwer, M.; Jacobs, M.J.; Vosse, van de F.N.

2009-01-01

Rupture risk estimation of abdominal aortic aneurysms (AAA) is currently based on the maximum diameter of the AAA. A more critical approach is based on AAA wall stress analysis. For that, in most cases, the AAA geometry is obtained from CT-data and treated as a stress free geometry. However, during

10th China-Japan Geometry Conference

CERN Document Server

Miyaoka, Reiko; Tang, Zizhou; Zhang, Weiping

2016-01-01

Since the year 2000, we have witnessed several outstanding results in geometry that have solved long-standing problems such as the Poincaré conjecture, the Yau–Tian–Donaldson conjecture, and the Willmore conjecture. There are still many important and challenging unsolved problems including, among others, the Strominger–Yau–Zaslow conjecture on mirror symmetry, the relative Yau–Tian–Donaldson conjecture in Kähler geometry, the Hopf conjecture, and the Yau conjecture on the first eigenvalue of an embedded minimal hypersurface of the sphere. For the younger generation to approach such problems and obtain the required techniques, it is of the utmost importance to provide them with up-to-date information from leading specialists. The geometry conference for the friendship of China and Japan has achieved this purpose during the past 10 years. Their talks deal with problems at the highest level, often accompanied with solutions and ideas, which extend across various fields in Riemannian geometry, sympl...

Development and fabrication of patient-specific knee implant using additive manufacturing techniques

Science.gov (United States)

Zammit, Robert; Rochman, Arif

2017-10-01

Total knee replacement is the most effective treatment to relief pain and restore normal function in a diseased knee joint. The aim of this research was to develop a patient-specific knee implant which can be fabricated using additive manufacturing techniques and has reduced wear rates using a highly wear resistant materials. The proposed design was chosen based on implant requirements, such as reduction in wear rates as well as strong fixation. The patient-specific knee implant improves on conventional knee implants by modifying the articulating surfaces and bone-implant interfaces. Moreover, tribological tests of different polymeric wear couples were carried out to determine the optimal materials to use for the articulating surfaces. Finite element analysis was utilized to evaluate the stresses sustained by the proposed design. Finally, the patient-specific knee implant was successfully built using additive manufacturing techniques.

The geometry ability of junior high school students in Karanganyar based on the Hoffer’s theory

Science.gov (United States)

Nurwijayanti, A.; Budiyono; Fitriana, L.

2018-03-01

Geometry ability is the aspect which underlay students to solve the geometry problems. However, some studies suggests the difficulty students when learning geometry. This leads to the ability of the geometri students difficult to develop. There are five the geometry ability based the Hoffer’s theory, namely visual, verbal, drawing, logical, and applied. These five aspects are basic geometry ability to be mastered by Junior High School students level. This study aimed to describe the students’ geometry ability according to the Hoffer’s theory. The participants of this study are six students from 9th grade in State Junior High School 1 Jaten at Karanganyar that consisted of three categories, namely higher ability, moderate ability, and lower ability students. The data collection methods used are geometry test and in-depth interview and than analyzed using triangulation. The result of the study showed that the ability of those three categories is different. Each of the students' geometry ability can be described as follows. (1) On visual skill, higher ability and moderate ability students could mention the elements of the geometrical shapes correctly based on its shapes obtained. However, lower ability students were unable to mention it specifically; (2) On verbal skill, moderate ability students were able to link the relationship among shapes based on the characteristics correctly, despite that the higher ability and lower ability seemed to have difficulty; (3) On drawing skill, higher ability students could construct the shapes based on the relationship among shapes well, but moderate ability and lower ability students continually faced difficulty; (4) On logical skill, both higher ability, and moderate ability students were able to determine the formula of a particular geometrical shape based on the relationship among the elements of the shape well, while the lower ability students were unable to; (5) On applied skill, higher ability, and moderate ability

Pathway index models for construction of patient-specific risk profiles.

Science.gov (United States)

Eng, Kevin H; Wang, Sijian; Bradley, William H; Rader, Janet S; Kendziorski, Christina

2013-04-30

Statistical methods for variable selection, prediction, and classification have proven extremely useful in moving personalized genomics medicine forward, in particular, leading to a number of genomic-based assays now in clinical use for predicting cancer recurrence. Although invaluable in individual cases, the information provided by these assays is limited. Most often, a patient is classified into one of very few groups (e.g., recur or not), limiting the potential for truly personalized treatment. Furthermore, although these assays provide information on which individuals are at most risk (e.g., those for which recurrence is predicted), they provide no information on the aberrant biological pathways that give rise to the increased risk. We have developed an approach to address these limitations. The approach models a time-to-event outcome as a function of known biological pathways, identifies important genomic aberrations, and provides pathway-based patient-specific assessments of risk. As we demonstrate in a study of ovarian cancer from The Cancer Genome Atlas project, the patient-specific risk profiles are powerful and efficient characterizations useful in addressing a number of questions related to identifying informative patient subtypes and predicting survival. Copyright © 2012 John Wiley & Sons, Ltd.

A dissipative particle dynamics method for arbitrarily complex geometries

Science.gov (United States)

Li, Zhen; Bian, Xin; Tang, Yu-Hang; Karniadakis, George Em

2018-02-01

Dissipative particle dynamics (DPD) is an effective Lagrangian method for modeling complex fluids in the mesoscale regime but so far it has been limited to relatively simple geometries. Here, we formulate a local detection method for DPD involving arbitrarily shaped geometric three-dimensional domains. By introducing an indicator variable of boundary volume fraction (BVF) for each fluid particle, the boundary of arbitrary-shape objects is detected on-the-fly for the moving fluid particles using only the local particle configuration. Therefore, this approach eliminates the need of an analytical description of the boundary and geometry of objects in DPD simulations and makes it possible to load the geometry of a system directly from experimental images or computer-aided designs/drawings. More specifically, the BVF of a fluid particle is defined by the weighted summation over its neighboring particles within a cutoff distance. Wall penetration is inferred from the value of the BVF and prevented by a predictor-corrector algorithm. The no-slip boundary condition is achieved by employing effective dissipative coefficients for liquid-solid interactions. Quantitative evaluations of the new method are performed for the plane Poiseuille flow, the plane Couette flow and the Wannier flow in a cylindrical domain and compared with their corresponding analytical solutions and (high-order) spectral element solution of the Navier-Stokes equations. We verify that the proposed method yields correct no-slip boundary conditions for velocity and generates negligible fluctuations of density and temperature in the vicinity of the wall surface. Moreover, we construct a very complex 3D geometry - the "Brown Pacman" microfluidic device - to explicitly demonstrate how to construct a DPD system with complex geometry directly from loading a graphical image. Subsequently, we simulate the flow of a surfactant solution through this complex microfluidic device using the new method. Its

An analysis of Landsat Thematic Mapper P-Product internal geometry and conformity to earth surface geometry

Science.gov (United States)

Bryant, N. A.; Zobrist, A. L.; Walker, R. E.; Gokhman, B.

1985-01-01

Performance requirements regarding geometric accuracy have been defined in terms of end product goals, but until recently no precise details have been given concerning the conditions under which that accuracy is to be achieved. In order to achieve higher spatial and spectral resolutions, the Thematic Mapper (TM) sensor was designed to image in both forward and reverse mirror sweeps in two separate focal planes. Both hardware and software have been augmented and changed during the course of the Landsat TM developments to achieve improved geometric accuracy. An investigation has been conducted to determine if the TM meets the National Map Accuracy Standards for geometric accuracy at larger scales. It was found that TM imagery, in terms of geometry, has come close to, and in some cases exceeded, its stringent specifications.

DOGBONE GEOMETRY FOR RECIRCULATING ACCELERATORS

International Nuclear Information System (INIS)

BERG, J.S.; JOHNSTONE, C.; SUMMERS, D.

2001-01-01

Most scenarios for accelerating muons require recirculating acceleration. A racetrack shape for the accelerator requires particles with lower energy in early passes to traverse almost the same length of arc as particles with the highest energy. This extra arc length may lead to excess decays and excess cost. Changing the geometry to a dogbone shape, where there is a single linac and the beam turns completely around at the end of the linac, returning to the same end of the linac from which it exited, addresses this problem. In this design, the arc lengths can be proportional to the particle's momentum. This paper proposes an approximate cost model for a recirculating accelerator, attempts to make cost-optimized designs for both racetrack and dogbone geometries, and demonstrates that the dogbone geometry does appear to be more cost effective

Observations of pretreatment prostate-specific antigen doubling time in 107 patients referred for definitive radiotherapy

International Nuclear Information System (INIS)

Lee, W. Robert; Hanks, Gerald E.; Corn, Benjamin W.; Schultheiss, Timothy E.

1995-01-01

Purpose: To determine pretreatment prostate-specific antigen doubling times (PSADT) in patients referred for definitive radiotherapy. Methods and Materials: One hundred and seven patients with histologically proven nonmetastatic prostate cancer and an elevated prostate-specific antigen (PSA) who were referred for radiation therapy had three serum PSA values obtained prior to the start of definitive therapy. Prostate-specific antigen doubling times were calculated by linear regression. Results: Prostate-specific antigen values increased during the period of observation in 78 patients (73%). Forty-three patients (40%) had calculated PSADT of less than 2 years and of those patients with pretreatment serum PSA values of greater than 10 ng/mL more than 50% has calculated PSADT of less than 2 years. Conclusions: A significant minority of patients referred for radiotherapy have calculated PSADT of less than 2 years. The significance of this relatively fast growth rate is as yet undetermined, but suggests that patients referred for radiotherapy may have aggressive disease prior to treatment

THE USE OF SPECIFIC AND NON-SPECIFIC QUESTIONNAIRES TO ASSESS QUALITY OF LIFE IN PATIENTS WITH FUNCTIONAL DISORDERS OF INTESTINE

Directory of Open Access Journals (Sweden)

A. E. Shklyaev

2016-01-01

Full Text Available Objective: comparative assessment of the quality of life of IBS patients in the treatment process with the use of specific and non-specific questionnaires.Materials and methods: a dynamic study of quality of life in 40 patients of IBS with the use of questionnaires GSRS and SF-36.Results: marked decrease in the severity of syndromes on all 6 scales of the questionnaire GSRS, and after 1 to 3 weeks of treatment dynamics was gained statistically significant, and total score improved significantly already after 1 week of therapy. Positive dynamics was obtained on the two scales of the questionnaire SF-36 (social functioning, and emotional functioning, as well as physical and psychological components of health.Conclusions: the high sensitivity of specific questionnaire GSRS and diagnostic significance of nonspecific SF-36 questionnaire in patients with IBS, the necessity to combine them.

Increasing insightful thinking in analytic geometry

NARCIS (Netherlands)

Timmer, Mark; Verhoef, Neeltje Cornelia

Elsewhere in this issue Ferdinand Verhulst described the discussion of the interaction of analysis and geometry in the 19th century. In modern times such discussions come up again and again. As of 2014, synthetic geometry will not be part of the Dutch 'vwo - mathematics B' programme anymore.

3D-Printed Patient-Specific ACL Femoral Tunnel Guide from MRI.

Science.gov (United States)

Rankin, Iain; Rehman, Haroon; Frame, Mark

2018-01-01

Traditional ACL reconstruction with non-anatomic techniques can demonstrate unsatisfactory long-term outcomes with regards instability and the degenerative knee changes observed with these results. Anatomic ACL reconstruction attempts to closely reproduce the patient's individual anatomic characteristics with the aim of restoring knee kinematics, in order to improve patient short and long-term outcomes. We designed an arthroscopic, patient-specific, ACL femoral tunnel guide to aid anatomical placement of the ACL graft within the femoral tunnel. The guide design was based on MRI scan of the subject's uninjured contralateral knee, identifying the femoral footprint and its anatomical position relative to the borders of the femoral articular cartilage. Image processing software was used to create a 3D computer aided design which was subsequently exported to a 3D-printing service. Transparent acrylic based photopolymer, PA220 plastic and 316L stainless steel patient-specific ACL femoral tunnel guides were created; the models produced were accurate with no statistical difference in size and positioning of the center of the ACL femoral footprint guide to MRI ( p =0.344, p =0.189, p =0.233 respectively). The guides aim to provide accurate marking of the starting point of the femoral tunnel in arthroscopic ACL reconstruction. This study serves as a proof of concept for the accurate creation of 3D-printed patient-specific guides for the anatomical placement of the femoral tunnel during ACL reconstruction.

Sarcomere lattice geometry influences cooperative myosin binding in muscle.

Directory of Open Access Journals (Sweden)

Bertrand C W Tanner

2007-07-01

Full Text Available In muscle, force emerges from myosin binding with actin (forming a cross-bridge. This actomyosin binding depends upon myofilament geometry, kinetics of thin-filament Ca(2+ activation, and kinetics of cross-bridge cycling. Binding occurs within a compliant network of protein filaments where there is mechanical coupling between myosins along the thick-filament backbone and between actin monomers along the thin filament. Such mechanical coupling precludes using ordinary differential equation models when examining the effects of lattice geometry, kinetics, or compliance on force production. This study uses two stochastically driven, spatially explicit models to predict levels of cross-bridge binding, force, thin-filament Ca(2+ activation, and ATP utilization. One model incorporates the 2-to-1 ratio of thin to thick filaments of vertebrate striated muscle (multi-filament model, while the other comprises only one thick and one thin filament (two-filament model. Simulations comparing these models show that the multi-filament predictions of force, fractional cross-bridge binding, and cross-bridge turnover are more consistent with published experimental values. Furthermore, the values predicted by the multi-filament model are greater than those values predicted by the two-filament model. These increases are larger than the relative increase of potential inter-filament interactions in the multi-filament model versus the two-filament model. This amplification of coordinated cross-bridge binding and cycling indicates a mechanism of cooperativity that depends on sarcomere lattice geometry, specifically the ratio and arrangement of myofilaments.

Nurses' Perceptions of Implementing Fall Prevention Interventions to Mitigate Patient-Specific Fall Risk Factors.

Science.gov (United States)

Wilson, Deleise S; Montie, Mary; Conlon, Paul; Reynolds, Margaret; Ripley, Robert; Titler, Marita G

2016-08-01

Evidence-based (EB) fall prevention interventions to mitigate patient-specific fall risk factors are readily available but not routinely used in practice. Few studies have examined nurses' perceptions about both the use of these EB interventions and implementation strategies designed to promote their adoption. This article reports qualitative findings of nurses' perceptions about use of EB fall prevention interventions to mitigate patient-specific fall risks, and implementation strategies to promote use of these interventions. The findings revealed five major themes: before-study fall prevention practices, use of EB fall prevention interventions tailored to patient-specific fall risk factors, beneficial implementation strategies, overall impact on approach to fall prevention, and challenges These findings are useful to guide nurses' engagement and use of EB fall prevention practices tailored to patient-specific fall risk factors. © The Author(s) 2016.

Rare myositis-specific autoantibody associations among Hungarian patients with idiopathic inflammatory myopathy.

Science.gov (United States)

Bodoki, L; Nagy-Vincze, M; Griger, Z; Betteridge, Z; Szöllősi, L; Jobanputra, R; Dankó, K

2015-01-01

Idiopathic inflammatory myopathies are systemic, chronic autoimmune diseases characterized by symmetrical, proximal muscle weakness. Homogeneous groups present with similar symptoms. The response to therapy and prognosis could be facilitated by myositis-specific autoantibodies, and in this way, give rise to immunoserological classification. The myositis-specific autoantibodies are directed against specific proteins found in the cytoplasm or in the nucleus of the cells. To date, literature suggests the rarity of the co-existence of two myositis-specific autoantibodies. In this study the authors highlight rare associations of myositis-specific autoantibodies. Three hundred and thirty-seven Hungarian patients with polymyositis or dermatomyositis were studied. Their clinical findings were noted retrospectively. Specific blood tests identified six patients with the rare co-existence of myositis-specific autoantibodies, anti-Jo-1 and anti-SRP, anti-Jo-1 and anti-Mi-2, anti-Mi-2 and anti-PL-12, anti-Mi-2 and anti-SRP, and anti-SRP and anti-PL-7, respectively. This case review aims to identify the clinical importance of these rare associations and their place within the immunoserological classification.

Studies on piston bowl geometries using single blend ratio of various non-edible oils.

Science.gov (United States)

Viswanathan, Karthickeyan; Pasupathy, Balamurugan

2017-07-01

The depletion of fossil fuels and hike in crude oil prices were some of the main reasons to explore new alternatives from renewable source of energy. This work presents the impact of various bowl geometries on diesel engine with diesel and biodiesel samples. Three non-edible oils were selected, namely pumpkin seed oil, orange oil and neem oil. These oils were converted into respective biodiesel using transesterification process in the presence of catalyst and alcohol. After transesterification process, the oils were termed as pumpkin seed oil methyl ester (PSOME), orange oil methyl ester (OME) and neem oil methyl ester (NOME), respectively. The engine used for experimentation was a single-cylinder four-stroke water-cooled direct-injection diesel engine and loads were applied to the engine using eddy current dynamometer. Two bowl geometries were developed, namely toroidal combustion chamber (TCC) and trapezoidal combustion chamber (TRCC). Also, the engine was inbuilt with hemispherical combustion chamber (HCC). The base line readings were recorded using neat diesel fuel with HCC for various loads. Followed by 20% of biodiesel mixed with 80% neat diesel for all prepared methyl esters and termed as B1 (20% PSOME with 80% diesel), B2 (20% OME with 80% diesel) and B3 (20% NOME with 80% diesel). All fuel samples were tested in HCC, TCC and TRCC bowl geometries under standard injection timing and with compression ratio of 18. Increased brake thermal efficiency and reduced brake specific fuel consumption were observed with diesel in TCC geometry. Also, higher heat release and cylinder pressures with lower ignition delay were recorded with TCC bowl geometry. TCC bowl geometry showed lower CO, HC and smoke emissions with B2 fuel sample than diesel and other biodiesel samples. But, higher NOx emission was observed in HCC and TCC than that in TRCC bowl geometry. Graphical abstract ᅟ.

Cell biology, MRI and geometry: insight into a microscopic/macroscopic marriage.

Science.gov (United States)

de Oliveira, Sérgio Almeida; Gowdak, Luís Henrique W; Buckberg, Gerald; Krieger, José Eduardo

2006-04-01

The concept of cell therapy as an adjunctive therapy to myocardial surgical revascularization for patients with severe coronary artery disease is illustrated by two case reports of ischemic cardiac disease that were unsuitable for revascularization by coronary grafting. The potential interaction of cell therapy, magnetic resonance imaging (MRI) of viability, and left ventricle (LV) restoration is described. Each patient had an ejection fraction below 30%, a relatively conical heart, and MRI gadolinium scan showing predominantly viable muscle. Intramyocardial injections of autologous bone marrow-derived cells (BMC) were performed along with either incomplete coronary artery bypass grafting (CABG) (to mother regions) or with transmyocardial laser revascularization (TMLR). An improvement in contractile function was seen at 6-12-month intervals after the procedure. The implications of possible underlying mechanisms of improvement in both myocardial perfusion and contractility suggest the striking importance of both micro- and macroenvironment for any cell-based therapeutic strategy. These observations imply that the interaction of cell biology, viability by MRI and geometry may be important in the future, as geometry can be restored surgically, and the new architectural form may develop enhanced function if it contains viable tissue and cell-based treatment can be delivered.

Remarks on Hamiltonian structures in G2-geometry

International Nuclear Information System (INIS)

Cho, Hyunjoo; Salur, Sema; Todd, A. J.

2013-01-01

In this article, we treat G 2 -geometry as a special case of multisymplectic geometry and make a number of remarks regarding Hamiltonian multivector fields and Hamiltonian differential forms on manifolds with an integrable G 2 -structure; in particular, we discuss existence and make a number of identifications of the spaces of Hamiltonian structures associated to the two multisymplectic structures associated to an integrable G 2 -structure. Along the way, we prove some results in multisymplectic geometry that are generalizations of results from symplectic geometry

SU-E-T-106: Development of a Collision Prediction Algorithm for Determining Problematic Geometry for SBRT Treatments Using a Stereotactic Body Frame

Energy Technology Data Exchange (ETDEWEB)

Wagar, M; Friesen, S; Mannarino, E [Dana-Farber/Brigham and Women' s Cancer Center, Boston, MA (United States); Hacker, F [Dana-Farber/Brigham and Women' s Cancer Center, Boston, MA (United States); Harvard Medical School, Boston, MA (United States)

2014-06-01

Purpose: Collision between the gantry and the couch or patient during Radiotherapy is not a common concern for conventional RT (static fields or arc). With the increase in the application of stereotactic planning techniques to the body, collisions have become a greater concern. Non-coplanar beam geometry is desirable in stereotatic treatments in order to achieve sharp gradients and a high conformality. Non-coplanar geometry is less intuitive in the body and often requires an iterative process of planning and dry runs to guarantee deliverability. Methods: Purpose written software was developed in order to predict the likelihood of collision between the head of the gantry and the couch, patient or stereotatic body frame. Using the DICOM plan and structures set, exported by the treatment planning system, this software is able to predict the possibility of a collision. Given the plan's isocenter, treatment geometry and exterior contours, the software is able to determine if a particular beam/arc is clinically deliverable or if collision is imminent. Results: The software was tested on real world treatment plans with untreatable beam geometry. Both static non-coplanar and VMAT plans were tested. Of these, the collision prediction software could identify all as having potentially problematic geometry. Re-plans of the same cases were also tested and validated as deliverable. Conclusion: This software is capable of giving good initial indication of deliverability for treatment plans that utilize complex geometry (SBRT) or have lateral isocenters. This software is not intended to replace the standard pre-treatment QA dry run. The effectiveness is limited to those portions of the patient and immobilization devices that have been included in the simulation CT and contoured in the planning system. It will however aid the planner in reducing the iterations required to create complex treatment geometries necessary to achieve ideal conformality and organ sparing.

Assessment of CT dose to the fetus and pregnant female patient using patient-specific computational models

Energy Technology Data Exchange (ETDEWEB)

Xie, Tianwu; Poletti, Pierre-Alexandre; Platon, Alexandra; Becker, Christoph D. [Geneva University Hospital, Department of Medical Imaging and Information Sciences, Geneva (Switzerland); Zaidi, Habib [Geneva University Hospital, Department of Medical Imaging and Information Sciences, Geneva (Switzerland); Geneva University, Geneva Neuroscience Center, Geneva (Switzerland); University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, University of Groningen, Groningen (Netherlands); University of Southern Denmark, Department of Nuclear Medicine, Odense (Denmark); Geneva University Hospital, Division of Nuclear Medicine and Molecular Imaging, Geneva (Switzerland)

2018-03-15

This work provides detailed estimates of the foetal dose from diagnostic CT imaging of pregnant patients to enable the assessment of the diagnostic benefits considering the associated radiation risks. To produce realistic biological and physical representations of pregnant patients and the embedded foetus, we developed a methodology for construction of patient-specific voxel-based computational phantoms based on existing standardised hybrid computational pregnant female phantoms. We estimated the maternal absorbed dose and foetal organ dose for 30 pregnant patients referred to the emergency unit of Geneva University Hospital for abdominal CT scans. The effective dose to the mother varied from 1.1 mSv to 2.0 mSv with an average of 1.6 mSv, while commercial dose-tracking software reported an average effective dose of 1.9 mSv (range 1.7-2.3 mSv). The foetal dose normalised to CTDI{sub vol} varies between 0.85 and 1.63 with an average of 1.17. The methodology for construction of personalised computational models can be exploited to estimate the patient-specific radiation dose from CT imaging procedures. Likewise, the dosimetric data can be used for assessment of the radiation risks to pregnant patients and the foetus from various CT scanning protocols, thus guiding the decision-making process. (orig.)

Ventriculostomy Simulation Using Patient-Specific Ventricular Anatomy, 3D Printing, and Hydrogel Casting.

Science.gov (United States)

Ryan, Justin R; Chen, Tsinsue; Nakaji, Peter; Frakes, David H; Gonzalez, L Fernando

2015-11-01

Educational simulators provide a means for students and experts to learn and refine surgical skills. Educators can leverage the strengths of medical simulators to effectively teach complex and high-risk surgical procedures, such as placement of an external ventricular drain. Our objective was to develop a cost-effective, patient-derived medical simulacrum for cerebral lateral ventriculostomy. A cost-effective, patient-derived medical simulacrum was developed for placement of an external lateral ventriculostomy. Elastomeric and gel casting techniques were used to achieve realistic brain geometry and material properties. 3D printing technology was leveraged to develop accurate cranial properties and dimensions. An economical, gravity-driven pump was developed to provide normal and abnormal ventricular pressures. A small pilot study was performed to gauge simulation efficacy using a technology acceptance model. An accurate geometric representation of the brain was developed with independent lateral cerebral ventricular chambers. A gravity-driven pump pressurized the ventricular cavities to physiologic values. A qualitative study illustrated that the simulation has potential as an educational tool to train medical professionals in the ventriculostomy procedure. The ventricular simulacrum can improve learning in a medical education environment. Rapid prototyping and multi-material casting techniques can produce patient-derived models for cost-effective and realistic surgical training scenarios. Copyright © 2015 Elsevier Inc. All rights reserved.

Elevated Cancer-Specific Mortality Among HIV-Infected Patients in the United States.

Science.gov (United States)

Coghill, Anna E; Shiels, Meredith S; Suneja, Gita; Engels, Eric A

2015-07-20

Despite advances in the treatment of HIV, HIV-infected people remain at increased risk for many cancers, and the number of non-AIDS-defining cancers is increasing with the aging of the HIV-infected population. No prior study has comprehensively evaluated the effect of HIV on cancer-specific mortality. We identified cases of 14 common cancers occurring from 1996 to 2010 in six US states participating in a linkage of cancer and HIV/AIDS registries. We used Cox regression to examine the association between patient HIV status and death resulting from the presenting cancer (ascertained from death certificates), adjusting for age, sex, race/ethnicity, year of cancer diagnosis, and cancer stage. We included 1,816,461 patients with cancer, 6,459 (0.36%) of whom were HIV infected. Cancer-specific mortality was significantly elevated in HIV-infected compared with HIV-uninfected patients for many cancers: colorectum (adjusted hazard ratio [HR], 1.49; 95% CI, 1.21 to 1.84), pancreas (HR, 1.71; 95% CI, 1.35 to 2.18), larynx (HR, 1.62; 95% CI, 1.06 to 2.47), lung (HR, 1.28; 95% CI, 1.17 to 1.39), melanoma (HR, 1.72; 95% CI, 1.09 to 2.70), breast (HR, 2.61; 95% CI, 2.06 to 3.31), and prostate (HR, 1.57; 95% CI, 1.02 to 2.41). HIV was not associated with increased cancer-specific mortality for anal cancer, Hodgkin lymphoma, or diffuse large B-cell lymphoma. After further adjustment for cancer treatment, HIV remained associated with elevated cancer-specific mortality for common non-AIDS-defining cancers: colorectum (HR, 1.40; 95% CI, 1.09 to 1.80), lung (HR, 1.28; 95% CI, 1.14 to 1.44), melanoma (HR, 1.93; 95% CI, 1.14 to 3.27), and breast (HR, 2.64; 95% CI, 1.86 to 3.73). HIV-infected patients with cancer experienced higher cancer-specific mortality than HIV-uninfected patients, independent of cancer stage or receipt of cancer treatment. The elevation in cancer-specific mortality among HIV-infected patients may be attributable to unmeasured stage or treatment differences as well

Classical geometry Euclidean, transformational, inversive, and projective

CERN Document Server

Leonard, I E; Liu, A C F; Tokarsky, G W

2014-01-01

Features the classical themes of geometry with plentiful applications in mathematics, education, engineering, and science Accessible and reader-friendly, Classical Geometry: Euclidean, Transformational, Inversive, and Projective introduces readers to a valuable discipline that is crucial to understanding bothspatial relationships and logical reasoning. Focusing on the development of geometric intuitionwhile avoiding the axiomatic method, a problem solving approach is encouraged throughout. The book is strategically divided into three sections: Part One focuses on Euclidean geometry, which p

MOCUM: A two-dimensional method of characteristics code based on constructive solid geometry and unstructured meshing for general geometries

International Nuclear Information System (INIS)

Yang Xue; Satvat, Nader

2012-01-01

Highlight: ► A two-dimensional numerical code based on the method of characteristics is developed. ► The complex arbitrary geometries are represented by constructive solid geometry and decomposed by unstructured meshing. ► Excellent agreement between Monte Carlo and the developed code is observed. ► High efficiency is achieved by parallel computing. - Abstract: A transport theory code MOCUM based on the method of characteristics as the flux solver with an advanced general geometry processor has been developed for two-dimensional rectangular and hexagonal lattice and full core neutronics modeling. In the code, the core structure is represented by the constructive solid geometry that uses regularized Boolean operations to build complex geometries from simple polygons. Arbitrary-precision arithmetic is also used in the process of building geometry objects to eliminate the round-off error from the commonly used double precision numbers. Then, the constructed core frame will be decomposed and refined into a Conforming Delaunay Triangulation to ensure the quality of the meshes. The code is fully parallelized using OpenMP and is verified and validated by various benchmarks representing rectangular, hexagonal, plate type and CANDU reactor geometries. Compared with Monte Carlo and deterministic reference solution, MOCUM results are highly accurate. The mentioned characteristics of the MOCUM make it a perfect tool for high fidelity full core calculation for current and GenIV reactor core designs. The detailed representation of reactor physics parameters can enhance the safety margins with acceptable confidence levels, which lead to more economically optimized designs.

Applications of patient-specific 3D printing in medicine.

Science.gov (United States)

Heller, Martin; Bauer, Heide-Katharina; Goetze, Elisabeth; Gielisch, Matthias; Roth, Klaus E; Drees, Philipp; Maier, Gerrit S; Dorweiler, Bernhard; Ghazy, Ahmed; Neufurth, Meik; Müller, Werner E G; Schröder, Heinz C; Wang, Xiaohong; Vahl, Christian-Friedrich; Al-Nawas, Bilal

Already three decades ago, the potential of medical 3D printing (3DP) or rapid prototyping for improved patient treatment began to be recognized. Since then, more and more medical indications in different surgical disciplines have been improved by using this new technique. Numerous examples have demonstrated the enormous benefit of 3DP in the medical care of patients by, for example, planning complex surgical interventions preoperatively, reducing implantation steps and anesthesia times, and helping with intraoperative orientation. At the beginning of every individual 3D model, patient-specific data on the basis of computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound data is generated, which is then digitalized and processed using computer-aided design/computer-aided manufacturing (CAD/CAM) software. Finally, the resulting data sets are used to generate 3D-printed models or even implants. There are a variety of different application areas in the various medical fields, eg, drill or positioning templates, or surgical guides in maxillofacial surgery, or patient-specific implants in orthopedics. Furthermore, in vascular surgery it is possible to visualize pathologies such as aortic aneurysms so as to improve the planning of surgical treatment. Although rapid prototyping of individual models and implants is already applied very successfully in regenerative medicine, most of the materials used for 3DP are not yet suitable for implantation in the body. Therefore, it will be necessary in future to develop novel therapy approaches and design new materials in order to completely reconstruct natural tissue.

Stability analysis of lower dimensional gravastars in noncommutative geometry

Energy Technology Data Exchange (ETDEWEB)

Banerjee, Ayan [Jadavpur University, Department of Mathematics, Kolkata (India); Hansraj, Sudan [University of KwaZulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, Durban (South Africa)

2016-11-15

The Banados et al. (Phys. Rev. Lett 69:1849, 1992), black hole solution is revamped from the Einstein field equations in (2 + 1)-dimensional anti-de Sitter spacetime, in a context of noncommutative geometry (Phys. Rev. D 87:084014, 2013). In this article, we explore the exact gravastar solutions in three-dimensional anti-de Sitter space given in the same geometry. As a first step we derive BTZ solution assuming the source of energy density as point-like structures in favor of smeared objects, where the particle mass M, is diffused throughout a region of linear size √(α) and is described by a Gaussian function of finite width rather than a Dirac delta function. We matched our interior solution to an exterior BTZ spacetime at a junction interface situated outside the event horizon. Furthermore, a stability analysis is carried out for the specific case when χ < 0.214 under radial perturbations about the static equilibrium solutions. To give theoretical support we are also trying to explore their physical properties and characteristics. (orig.)

Patient-specific scatter correction in clinical cone beam computed tomography imaging made possible by the combination of Monte Carlo simulations and a ray tracing algorithm

International Nuclear Information System (INIS)

Thing, Rune S.; Bernchou, Uffe; Brink, Carsten; Mainegra-Hing, Ernesto

2013-01-01

Purpose: Cone beam computed tomography (CBCT) image quality is limited by scattered photons. Monte Carlo (MC) simulations provide the ability of predicting the patient-specific scatter contamination in clinical CBCT imaging. Lengthy simulations prevent MC-based scatter correction from being fully implemented in a clinical setting. This study investigates the combination of using fast MC simulations to predict scatter distributions with a ray tracing algorithm to allow calibration between simulated and clinical CBCT images. Material and methods: An EGSnrc-based user code (egs c bct), was used to perform MC simulations of an Elekta XVI CBCT imaging system. A 60keV x-ray source was used, and air kerma scored at the detector plane. Several variance reduction techniques (VRTs) were used to increase the scatter calculation efficiency. Three patient phantoms based on CT scans were simulated, namely a brain, a thorax and a pelvis scan. A ray tracing algorithm was used to calculate the detector signal due to primary photons. A total of 288 projections were simulated, one for each thread on the computer cluster used for the investigation. Results: Scatter distributions for the brain, thorax and pelvis scan were simulated within 2 % statistical uncertainty in two hours per scan. Within the same time, the ray tracing algorithm provided the primary signal for each of the projections. Thus, all the data needed for MC-based scatter correction in clinical CBCT imaging was obtained within two hours per patient, using a full simulation of the clinical CBCT geometry. Conclusions: This study shows that use of MC-based scatter corrections in CBCT imaging has a great potential to improve CBCT image quality. By use of powerful VRTs to predict scatter distributions and a ray tracing algorithm to calculate the primary signal, it is possible to obtain the necessary data for patient specific MC scatter correction within two hours per patient

Dayside merging and cusp geometry

International Nuclear Information System (INIS)

Crooker, N.U.

1979-01-01

Geometrical considerations are presented to show that dayside magnetic merging when constrained to act only where the fields are antiparallel results in lines of merging that converge at the polar cusps. An important consequence of this geometry is that no accelerated flows are predicted across the dayside magnetopause. Acceleration owing to merging acts in opposition to the magnetosheath flow at the merging point and produces the variably directed, slower-than-magnetosheath flows observed in the entry layer. Another consequence of the merging geometry is that much of the time closed field lines constitute the subsolar region of the magnetopause. The manner in which the polar cap convection patterns predicted by the proposed geometry change as the interplanetary field is rotated through 360 0 provides a unifying description of how the observed single circular vortex and the crescent-shaped double vortex patterns mutually evolve under the influence of a single operating principle

Assessment of CT dose to the fetus and pregnant female patient using patient-specific computational models

DEFF Research Database (Denmark)

Xie, Tianwu; Poletti, Pierre-Alexandre; Platon, Alexandra

2018-01-01

of pregnant patients and the embedded foetus, we developed a methodology for construction of patient-specific voxel-based computational phantoms based on existing standardised hybrid computational pregnant female phantoms. We estimated the maternal absorbed dose and foetal organ dose for 30 pregnant patients...... for assessment of the radiation risks to pregnant patients and the foetus from various CT scanning protocols, thus guiding the decision-making process. KEY POINTS: • In CT examinations, the absorbed dose is non-uniformly distributed within foetal organs. • This work reports, for the first time, estimates...

Patient specific root-analogue dental implants – additive manufacturing and finite element analysis

Directory of Open Access Journals (Sweden)

Gattinger Johannes

2016-09-01

Full Text Available Aim of this study was to prove the possibility of manufacturing patient specific root analogue two-part (implant and abutment implants by direct metal laser sintering. The two-part implant design enables covered healing of the implant. Therefore, CT-scans of three patients are used for reverse engineering of the implants, abutments and crowns. Patient specific implants are manufactured and measured concerning dimensional accuracy and surface roughness. Impacts of occlusal forces are simulated via FEA and compared to those of standard implants.

Digital and discrete geometry theory and algorithms

CERN Document Server

Chen, Li

2014-01-01

This book provides comprehensive coverage of the modern methods for geometric problems in the computing sciences. It also covers concurrent topics in data sciences including geometric processing, manifold learning, Google search, cloud data, and R-tree for wireless networks and BigData.The author investigates digital geometry and its related constructive methods in discrete geometry, offering detailed methods and algorithms. The book is divided into five sections: basic geometry; digital curves, surfaces and manifolds; discretely represented objects; geometric computation and processing; and a

Optimization of combustion chamber geometry for stoichiometric diesel combustion using a micro genetic algorithm

Energy Technology Data Exchange (ETDEWEB)

Park, Sung Wook

2010-11-15

This paper describes the optimization of combustion chamber geometry and engine operating conditions for stoichiometric diesel combustion, targeting lower gross indicated specific fuel consumption. The KIVA code, coupled with a micro genetic algorithm population of nine for each generation was used. The optimization variables were composed of ten variables related to the combustion chamber geometry and engine operating conditions. In addition, an auto mesh generator was developed for generating various kinds of combustion chambers, such as open-crater, re-entrant, deep, and shallow types. In addition, the computational models were validated against the experimental results for a stoichiometric process in terms of the combustion pressure history and emissions. Through the preset optimization, a 35% improvement in the gross indicated that specific fuel consumption was achieved. In addition, the optimization results showed that the optimum engine operating conditions employed a premixed charge compression ignition combustion regime with early injection and a narrow spray included angle. Furthermore, a higher boost pressure was used to prevent fuel film formation. (author)

Patient-Specific Variations in Biomarkers across Gingivitis and Periodontitis

Science.gov (United States)

Nagarajan, Radhakrishnan; Miller, Craig S.; Dawson, Dolph; Al-Sabbagh, Mohanad; Ebersole, Jeffrey L.

2015-01-01

This study investigates the use of saliva, as an emerging diagnostic fluid in conjunction with classification techniques to discern biological heterogeneity in clinically labelled gingivitis and periodontitis subjects (80 subjects; 40/group) A battery of classification techniques were investigated as traditional single classifier systems as well as within a novel selective voting ensemble classification approach (SVA) framework. Unlike traditional single classifiers, SVA is shown to reveal patient-specific variations within disease groups, which may be important for identifying proclivity to disease progression or disease stability. Salivary expression profiles of IL-1ß, IL-6, MMP-8, and MIP-1α from 80 patients were analyzed using four classification algorithms (LDA: Linear Discriminant Analysis [LDA], Quadratic Discriminant Analysis [QDA], Naïve Bayes Classifier [NBC] and Support Vector Machines [SVM]) as traditional single classifiers and within the SVA framework (SVA-LDA, SVA-QDA, SVA-NB and SVA-SVM). Our findings demonstrate that performance measures (sensitivity, specificity and accuracy) of traditional classification as single classifier were comparable to that of the SVA counterparts using clinical labels of the samples as ground truth. However, unlike traditional single classifier approaches, the normalized ensemble vote-counts from SVA revealed varying proclivity of the subjects for each of the disease groups. More importantly, the SVA identified a subset of gingivitis and periodontitis samples that demonstrated a biological proclivity commensurate with the other clinical group. This subset was confirmed across SVA-LDA, SVA-QDA, SVA-NB and SVA-SVM. Heatmap visualization of their ensemble sets revealed lack of consensus between these subsets and the rest of the samples within the respective disease groups indicating the unique nature of the patients in these subsets. While the source of variation is not known, the results presented clearly elucidate the

On the Importance of Solar Eclipse Geometry in the Interpretation of Ionospheric Observations

Science.gov (United States)

Stankov, S.; Verhulst, T. G. W.

2017-12-01

A reliable interpretation of solar eclipse effects on the geospace environment, and on the ionosphere in particular, necessitates a careful consideration of the so-called eclipse geometry. A solar eclipse is a relatively rare astronomical phenomenon, which geometry is rather complex, specific for each event, and fast changing in time. The standard, most popular way to look at the eclipse geometry is via the two-dimensional representation (map) of the solar obscuration on the Earth's surface, in which the path of eclipse totality is drawn together with isolines of the gradually-decreasing eclipse magnitude farther away from this path. Such "surface maps" are widely used to readily explain some of the solar eclipse effects including, for example, the well-known decrease in total ionisation (due to the substantial decrease in solar irradiation), usually presented by the popular and easy to understand ionospheric characteristic of Total Electron Content (TEC). However, many other effects, especially those taking place at higher altitudes, cannot be explained in this fashion. Instead, a complete, four-dimensional (4D) description of the umbra (and penumbra), would be required. This presentation will address the issue of eclipse geometry effects on various ionospheric observations carried out during the total solar eclipse of August 21, 2017. In particular, GPS-based TEC and ionosonde measurements will be analysed and the eclipse effects on the ionosphere will be interpreted with respect to the actual eclipse geometry at ionospheric heights. Whenever possible, a comparison will be made with results from previous events, such as the ones from March 20, 2015 and October 3, 2005.

Attitudes of High School Students towards Geometry

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Esat Avcı

2014-12-01

Full Text Available In this research, attitudes of high school students towards geometry were investigated in terms of gender, grade, types of the field and school. Population of research includes students who were studying at high school in five distincs of Mersin in 2013-2014 academical year. Sample of research includes 935 students from twelve high schools. Attitude scale which was developed by Su-Özenir (2008 was used for data collection. For data analysis, mean, standart deviation, t test and ANOVA were used. A meaningful difference between students’ attitudes towards geometry and variance of gender and grade level wasn’t observed, on the other hand a meaningful difference according to field and school type is observed.Key Words:    Attitudes towards geometry, high school geometry lesson, attitude scale

Photonic crystal geometry for organic solar cells.

Science.gov (United States)

Ko, Doo-Hyun; Tumbleston, John R; Zhang, Lei; Williams, Stuart; DeSimone, Joseph M; Lopez, Rene; Samulski, Edward T

2009-07-01

We report organic solar cells with a photonic crystal nanostructure embossed in the photoactive bulk heterojunction layer, a topography that exhibits a 3-fold enhancement of the absorption in specific regions of the solar spectrum in part through multiple excitation resonances. The photonic crystal geometry is fabricated using a materials-agnostic process called PRINT wherein highly ordered arrays of nanoscale features are readily made in a single processing step over wide areas (approximately 4 cm(2)) that is scalable. We show efficiency improvements of approximately 70% that result not only from greater absorption, but also from electrical enhancements. The methodology is generally applicable to organic solar cells and the experimental findings reported in our manuscript corroborate theoretical expectations.

Modeling cavities exhibiting strong lateral confinement using open geometry Fourier modal method

Science.gov (United States)

Häyrynen, Teppo; Gregersen, Niels

2016-04-01

We have developed a computationally efficient Fourier-Bessel expansion based open geometry formalism for modeling the optical properties of rotationally symmetric photonic nanostructures. The lateral computation domain is assumed infinite so that no artificial boundary conditions are needed. Instead, the leakage of the modes due to an imperfect field confinement is taken into account by using a basis functions that expand the whole infinite space. The computational efficiency is obtained by using a non-uniform discretization in the frequency space in which the lateral expansion modes are more densely sampled around a geometry specific dominant transverse wavenumber region. We will use the developed approach to investigate the Q factor and mode confinement in cavities where top DBR mirror has small rectangular defect confining the modes laterally on the defect region.

The Specificity of Health-Related Autobiographical Memories in Patients With Somatic Symptom Disorder.

Science.gov (United States)

Walentynowicz, Marta; Raes, Filip; Van Diest, Ilse; Van den Bergh, Omer

2017-01-01

Patients with somatic symptom disorder (SSD) have persistent distressing somatic symptoms that are associated with excessive thoughts, feelings, and behaviors. Reduced autobiographical memory specificity (rAMS) is related to a range of emotional disorders and is considered a vulnerability factor for an unfavorable course of pathology. The present study investigated whether the specificity of health-related autobiographical memories is reduced in patients with SSD with medically unexplained dyspnea complaints, compared with healthy controls. Female patients with SSD (n = 30) and matched healthy controls (n = 24) completed a health-related Autobiographical Memory Test, the Beck Depression Inventory, the Ruminative Response Scale, and rumination scales concerning bodily reactions. Depressive symptoms and rumination were assessed because both variables previously showed associations with rAMS. Patients with SSD recalled fewer specific (F(1,52) = 13.63, p = .001) and more categoric (F(1,52) = 7.62, p = .008) autobiographical memories to health-related cue words than healthy controls. Patients also reported higher levels of depressive symptoms and rumination (all t > 3.00, p < .01). Importantly, the differences in memory specificity were independent of depressive symptoms and trait rumination. The present study extends findings on rAMS to a previously unstudied sample of patients with SSD. Importantly, the presence of rAMS could not be explained by increased levels of depressive symptoms and rumination. We submit that rAMS in this group reflects how health-related episodes and associated symptoms are encoded in memory.

Commutative and Non-commutative Parallelogram Geometry: an Experimental Approach

OpenAIRE

Bertram, Wolfgang

2013-01-01

By "parallelogram geometry" we mean the elementary, "commutative", geometry corresponding to vector addition, and by "trapezoid geometry" a certain "non-commutative deformation" of the former. This text presents an elementary approach via exercises using dynamical software (such as geogebra), hopefully accessible to a wide mathematical audience, from undergraduate students and high school teachers to researchers, proceeding in three steps: (1) experimental geometry, (2) algebra (linear algebr...

A Correlation Study between Geometry of Collared Coils and Normal Quadrupole Multipole in the Main LHC Dipoles

CERN Document Server

Bertinelli, F; Berthollon-Vitte, S; Glaude, D; Vanenkov, I

2006-01-01

The quality control implemented at all LHC dipole assemblers includes precise mechanical measurements of the geometry of collared coils. A cross-analysis performed between mechanical and magnetic measurements data shows a correlation between collared coils outer dimensions and the normal quadrupole multipole (b2) for one dipole assembler. The profile geometry of the single collars - as determined from 3D measurements at the collar suppliers and CERN - could not account alone for the significant left – right aperture asymmetry observed. This triggered a deeper investigation on different elements of the geometry of single collars. The results of this work show that the relative positioning of the collaring holes, allowing a small bending deformation of collars under the effect of coil pre-stress, is an important effect that generates a b2 multipole at the limit of specification. The study has deepened the understanding of the factors affecting collared coil geometry and field quality. The precision of 3D m...

A Study of Geometry Content Knowledge of Elementary Preservice Teachers

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Fatma ASLAN-TUTAK

2015-06-01

Full Text Available The purpose of this research is to examine preservice elementary school teachers’ geometry learning as investigated by both qualitative and quantitative methods. For the qualitative investigation, narrative analysis and thematic analysis methods were used. The findings of narrative analysis indicated two main kinds of stories: as a learner and as a beginning teacher. The thematic analysis findings yield to three themes: history of learning geometry, perceptions about geometry, effective geometry instructional practices. The findings informed the quantitative investigation on geometry content knowledge for the case of quadrilaterals. During the second phase of the study, 102 participants who enrolled in the methods course completed pre and post test of teachers’ geometry content knowledge. Treatment group participants (n=54 received series of activities (geometry activities and student work analysis focusing on quadrilaterals, and control group participants (n=48 received traditional instruction. Repeated measures ANOVA results showed a significant change in treatment group participants’ geometry content knowledge. The mixed ANOVA results indicated a significant main effect of knowledge but no significant interaction between geometry content knowledge and grouping. Even though treatment group participants’ geometry content knowledge growth was significant, the difference between treatment group and control group participants’ growth in geometry content knowledge was not significant. This study informs mathematics teacher education in three important areas; limited knowledge of preservice teachers’ geometry content knowledge, integrating mathematics content and the context of teaching into methods course, and use of student work with preservice teachers.

A study of geometry content knowledge of elementary preservice teachers

Directory of Open Access Journals (Sweden)

Fatma Aslan Tutak

2015-06-01

Full Text Available The purpose of this research is to examine preservice elementary school teachers’ geometry learning as investigated by both qualitative and quantitative methods. For the qualitative investigation, narrative analysis and thematic analysis methods were used. The findings of narrative analysis indicated two main kinds of stories: as a learner and as a beginning teacher. The thematic analysis findings yield to three themes: history of learning geometry, perceptions about geometry, effective geometry instructional practices. The findings informed the quantitative investigation on geometry content knowledge for the case of quadrilaterals. During the second phase of the study, 102 participants who enrolled in the methods course completed pre and post test of teachers’ geometry content knowledge. Treatment group participants (n=54 received series of activities (geometry activities and student work analysis focusing on quadrilaterals, and control group participants (n=48 received traditional instruction. Repeated measures ANOVA results showed a significant change in treatment group participants’ geometry content knowledge. The mixed ANOVA results indicated a significant main effect of knowledge but no significant interaction between geometry content knowledge and grouping. Even though treatment group participants’ geometry content knowledge growth was significant, the difference between treatment group and control group participants’ growth in geometry content knowledge was not significant. This study informs mathematics teacher education in three important areas; limited knowledge of preservice teachers’ geometry content knowledge, integrating mathematics content and the context of teaching into methods course, and use of student work with preservice teachers.

Topology and geometry for physicists

CERN Document Server

Nash, Charles

1983-01-01

Differential geometry and topology are essential tools for many theoretical physicists, particularly in the study of condensed matter physics, gravity, and particle physics. Written by physicists for physics students, this text introduces geometrical and topological methods in theoretical physics and applied mathematics. It assumes no detailed background in topology or geometry, and it emphasizes physical motivations, enabling students to apply the techniques to their physics formulas and research. ""Thoroughly recommended"" by The Physics Bulletin, this volume's physics applications range fr

Fundamental concepts of geometry

CERN Document Server

Meserve, Bruce E

1983-01-01

Demonstrates relationships between different types of geometry. Provides excellent overview of the foundations and historical evolution of geometrical concepts. Exercises (no solutions). Includes 98 illustrations.

Monte Carlo simulations of magnetic and thermodynamic properties for different nanostructure geometries

Energy Technology Data Exchange (ETDEWEB)

Konstantinova, Elena, E-mail: elena.konst@ifsudestemg.edu.br; Sales, José Antonio de

2014-10-01

Creation of magnetic nanodevices leads, in particular, to a growing interest in theoretical investigation of different types of magnetic nanostructures. The purpose of our work is to consider how the properties of such nanomaterials depend on their geometry and on the crystal structure. We report on the Monte Carlo simulation of magnetic nanostructures of different geometric forms, which are based on simple cubic and body-centered cubic cells. The magnetization of spin, magnetic susceptibility and specific heat are investigated for nano-disks, nano-bars and nano-balls of different magnitudes. The combination of dipole and Heisenberg-model interaction are considered for the ferromagnetic case. It is shown that magnetic and thermodynamic properties of nanostructures strongly depend on their geometry. The structures with a body-centered cubic unit cell manifest stronger dependence on size and geometric form. In this case one can interpret the results as an effective reduction of dimension from 3D to 2D for decreasing size of the compound. - Highlights: • Thermodynamic properties of nano-balls are dependent on their size. • Magnetic properties of nano-bars depend on their thickness. • The hysteresis loop is dependent on the geometry of the nanostructure.

Non-commutative geometry inspired charged black holes

International Nuclear Information System (INIS)

Ansoldi, Stefano; Nicolini, Piero; Smailagic, Anais; Spallucci, Euro

2007-01-01

We find a new, non-commutative geometry inspired, solution of the coupled Einstein-Maxwell field equations describing a variety of charged, self-gravitating objects, including extremal and non-extremal black holes. The metric smoothly interpolates between de Sitter geometry, at short distance, and Reissner-Nordstrom geometry far away from the origin. Contrary to the ordinary Reissner-Nordstrom spacetime there is no curvature singularity in the origin neither 'naked' nor shielded by horizons. We investigate both Hawking process and pair creation in this new scenario

Indentation versus Rolling: Dependence of Adhesion on Contact Geometry for Biomimetic Structures.

Science.gov (United States)

Moyle, Nichole; He, Zhenping; Wu, Haibin; Hui, Chung-Yuen; Jagota, Anand

2018-04-03

Numerous biomimetic structures made from elastomeric materials have been developed to produce enhancement in properties such as adhesion, static friction, and sliding friction. As a property, one expects adhesion to be represented by an energy per unit area that is usually sensitive to the combination of shear and normal stresses at the crack front but is otherwise dependent only on the two elastic materials that meet at the interface. More specifically, one would expect that adhesion measured by indentation (a popular and convenient technique) could be used to predict adhesion hysteresis in the more practically important rolling geometry. Previously, a structure with a film-terminated fibrillar geometry exhibited dramatic enhancement of adhesion by a crack-trapping mechanism during indentation with a rigid sphere. Roughly isotropic structures such as the fibrillar geometry show a strong correlation between adhesion enhancement in indentation versus adhesion hysteresis in rolling. However, anisotropic structures, such as a film-terminated ridge-channel geometry, surprisingly show a dramatic divergence between adhesion measured by indentation versus rolling. We study this experimentally and theoretically, first comparing the adhesion of the anisotropic ridge-channel structure to the roughly isotropic fibrillar structure during indentation with a rigid sphere, where only the isotropic structure shows adhesion enhancement. Second, we examine in more detail the anomalous anisotropic film-terminated ridge-channel structure during indentation with a rigid sphere versus rolling to show why these structures show a dramatic adhesion enhancement for the rolling case and no adhesion enhancement for indentation.