Complete Scene Recovery and Terrain Classification in Textured Terrain Meshes

PubMed Central

Song, Wei; Cho, Kyungeun; Um, Kyhyun; Won, Chee Sun; Sim, Sungdae

2012-01-01

Terrain classification allows a mobile robot to create an annotated map of its local environment from the three-dimensional (3D) and two-dimensional (2D) datasets collected by its array of sensors, including a GPS receiver, gyroscope, video camera, and range sensor. However, parts of objects that are outside the measurement range of the range sensor will not be detected. To overcome this problem, this paper describes an edge estimation method for complete scene recovery and complete terrain reconstruction. Here, the Gibbs-Markov random field is used to segment the ground from 2D videos and 3D point clouds. Further, a masking method is proposed to classify buildings and trees in a terrain mesh. PMID:23112653

DeepMeSH: deep semantic representation for improving large-scale MeSH indexing.

PubMed

Peng, Shengwen; You, Ronghui; Wang, Hongning; Zhai, Chengxiang; Mamitsuka, Hiroshi; Zhu, Shanfeng

2016-06-15

Medical Subject Headings (MeSH) indexing, which is to assign a set of MeSH main headings to citations, is crucial for many important tasks in biomedical text mining and information retrieval. Large-scale MeSH indexing has two challenging aspects: the citation side and MeSH side. For the citation side, all existing methods, including Medical Text Indexer (MTI) by National Library of Medicine and the state-of-the-art method, MeSHLabeler, deal with text by bag-of-words, which cannot capture semantic and context-dependent information well. We propose DeepMeSH that incorporates deep semantic information for large-scale MeSH indexing. It addresses the two challenges in both citation and MeSH sides. The citation side challenge is solved by a new deep semantic representation, D2V-TFIDF, which concatenates both sparse and dense semantic representations. The MeSH side challenge is solved by using the 'learning to rank' framework of MeSHLabeler, which integrates various types of evidence generated from the new semantic representation. DeepMeSH achieved a Micro F-measure of 0.6323, 2% higher than 0.6218 of MeSHLabeler and 12% higher than 0.5637 of MTI, for BioASQ3 challenge data with 6000 citations. The software is available upon request. zhusf@fudan.edu.cn Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

DeepMeSH: deep semantic representation for improving large-scale MeSH indexing

PubMed Central

Peng, Shengwen; You, Ronghui; Wang, Hongning; Zhai, Chengxiang; Mamitsuka, Hiroshi; Zhu, Shanfeng

2016-01-01

Motivation: Medical Subject Headings (MeSH) indexing, which is to assign a set of MeSH main headings to citations, is crucial for many important tasks in biomedical text mining and information retrieval. Large-scale MeSH indexing has two challenging aspects: the citation side and MeSH side. For the citation side, all existing methods, including Medical Text Indexer (MTI) by National Library of Medicine and the state-of-the-art method, MeSHLabeler, deal with text by bag-of-words, which cannot capture semantic and context-dependent information well. Methods: We propose DeepMeSH that incorporates deep semantic information for large-scale MeSH indexing. It addresses the two challenges in both citation and MeSH sides. The citation side challenge is solved by a new deep semantic representation, D2V-TFIDF, which concatenates both sparse and dense semantic representations. The MeSH side challenge is solved by using the ‘learning to rank’ framework of MeSHLabeler, which integrates various types of evidence generated from the new semantic representation. Results: DeepMeSH achieved a Micro F-measure of 0.6323, 2% higher than 0.6218 of MeSHLabeler and 12% higher than 0.5637 of MTI, for BioASQ3 challenge data with 6000 citations. Availability and Implementation: The software is available upon request. Contact: zhusf@fudan.edu.cn Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27307646

MeSH indexing based on automatically generated summaries.

PubMed

Jimeno-Yepes, Antonio J; Plaza, Laura; Mork, James G; Aronson, Alan R; Díaz, Alberto

2013-06-26

MEDLINE citations are manually indexed at the U.S. National Library of Medicine (NLM) using as reference the Medical Subject Headings (MeSH) controlled vocabulary. For this task, the human indexers read the full text of the article. Due to the growth of MEDLINE, the NLM Indexing Initiative explores indexing methodologies that can support the task of the indexers. Medical Text Indexer (MTI) is a tool developed by the NLM Indexing Initiative to provide MeSH indexing recommendations to indexers. Currently, the input to MTI is MEDLINE citations, title and abstract only. Previous work has shown that using full text as input to MTI increases recall, but decreases precision sharply. We propose using summaries generated automatically from the full text for the input to MTI to use in the task of suggesting MeSH headings to indexers. Summaries distill the most salient information from the full text, which might increase the coverage of automatic indexing approaches based on MEDLINE. We hypothesize that if the results were good enough, manual indexers could possibly use automatic summaries instead of the full texts, along with the recommendations of MTI, to speed up the process while maintaining high quality of indexing results. We have generated summaries of different lengths using two different summarizers, and evaluated the MTI indexing on the summaries using different algorithms: MTI, individual MTI components, and machine learning. The results are compared to those of full text articles and MEDLINE citations. Our results show that automatically generated summaries achieve similar recall but higher precision compared to full text articles. Compared to MEDLINE citations, summaries achieve higher recall but lower precision. Our results show that automatic summaries produce better indexing than full text articles. Summaries produce similar recall to full text but much better precision, which seems to indicate that automatic summaries can efficiently capture the most important contents within the original articles. The combination of MEDLINE citations and automatically generated summaries could improve the recommendations suggested by MTI. On the other hand, indexing performance might be dependent on the MeSH heading being indexed. Summarization techniques could thus be considered as a feature selection algorithm that might have to be tuned individually for each MeSH heading.

The Role of the Surgeon on Outcomes of Vaginal Prolapse Surgery With Mesh.

PubMed

Eilber, Karyn S; Alperin, Marianna; Khan, Aqsa; Wu, Ning; Pashos, Chris L; Clemens, J Quentin; Anger, Jennifer T

Adverse outcomes after surgery for pelvic organ prolapse (POP) with mesh are often attributed to the mesh material with little attention paid to the influence of surgeon factors. We used a national data set to determine whether surgeon case volume and specialty influenced vaginal prolapse surgery outcomes with mesh. Public Use File data on a 5% random national sample of female Medicare beneficiaries were obtained from the Centers for Medicare and Medicaid Services. Women with a diagnosis of POP who underwent surgery with mesh between 2007 and 2008 were identified by relevant International Classification of Diseases, 9th Revision, Clinical Modification and Current Procedural Terminology, 4th Edition procedure codes. Outcomes were compared by surgeon case volume and specialty. From 2007 to 2008, 1657 surgeries for POP were performed with mesh. Low-, intermediate-, and high-volume surgeons performed 881 (53%), 408 (25%), and 368 (22%) of the cases with mesh, respectively. The cumulative reoperation rates for low-, intermediate-, and high-volume providers were 6%, 2%, and 3%, respectively. The difference in reoperation rates between low and intermediate and low- and high-volume surgeons was statistically significant (P = 0.007 and 0.003, respectively). There was no significant difference in reoperation rates between gynecologists and urologists when vaginal mesh was implanted for POP surgery. Low-volume surgeons performed most of the vaginal prolapse repairs with mesh and had significantly higher reoperation rates. Surgeon experience must be a consideration when reporting mesh-related complications of POP surgery.

Towards linking patients and clinical information: detecting UMLS concepts in e-mail.

PubMed

Brennan, Patricia Flatley; Aronson, Alan R

2003-01-01

The purpose of this project is to explore the feasibility of detecting terms within the electronic messages of patients that could be used to effectively search electronic knowledge resources and bring health information resources into the hands of patients. Our team is exploring the application of the natural language processing (NLP) tools built within the Lister Hill Center at the National Library of Medicine (NLM) to the challenge of detecting relevant concepts from the Unified Medical Language System (UMLS) within the free text of lay people's electronic messages (e-mail). We obtained a sample of electronic messages sent by patients participating in a randomized field evaluation of an internet-based home care support service to the project nurse, and we subjected elements of these messages to a series of analyses using several vocabularies from the UMLS Metathesaurus and the selected NLP tools. The nursing vocabularies provide an excellent starting point for this exercise because their domain encompasses patient's responses to health challenges. In successive runs we augmented six nursing vocabularies (NANDA Nursing Diagnosis, Nursing Interventions Classification, Nursing Outcomes Classification, Home Health Classification, Omaha System, and the Patient Care Data Set) with selected sets of clinical terminologies (International Classification of Primary Care; International Classification of Primary Care- American English; Micromedex DRUGDEX; National Drug Data File; Thesaurus of Psychological Terms; WHO Adverse Drug Reaction Terminology) and then additionally with either Medical Subject Heading (MeSH) or SNOMED International terms. The best performance was obtained when the nursing vocabularies were complemented with selected clinical terminologies. These findings have implications not only for facilitating lay people's access to electronic knowledge resources but may also be of assistance in developing new tools to aid in linking free text (e.g., clinical notes) to lexically complex knowledge resources such as those emerging from the Human Genome Project.

Effects of mesh-related complications in vaginal surgery on quality of life.

PubMed

Kowalik, Claudia R; Lakeman, Mariëlle M E; de Kraker, Alyde T; Roovers, Jan Paul W R

2018-06-16

Vaginal mesh surgery is subject of debate due to the impact of mesh-related complications on patient's lives. Not all of these complications are symptomatic. Restoration of the anatomy and improvement of pelvic floor function as a result may counter the experienced discomfort related to adverse events. We hypothesized that health-related quality of life (HR-QoL) is comparable in women after vaginal mesh surgery regardless of the presence or absence of a mesh-specific complication. This was a cross-sectional study of 128 women who had vaginal mesh surgery in a Dutch university hospital between 2007 and 2012. HR-QoL was measured in women with and without mesh complications using standardized QoL questionnaires Urogenital Distress Inventory-6 (UDI-6), Incontinence Impact Questionnaire (IIQ), Defecation Distress Inventory (DDI), and Pelvic Organ Prolapse/Urinary Incontinence Sexual Function Questionnaire (PISQ-12). Complications were scored according to the International Urogynecological Association (IUGA) complication classification. Comparisons between groups were performed with Student's t test and analysis of variance (ANOVA) test. In 29 (23%) women, a mesh-related complication occurred. The domain scores of the UDI-6, DDI, IIQ, and PISQ showed no statistically significant differences between women with and without a mesh-related complication. A post hoc analysis showed similar HR-QoL for those in whom the complication had been resolved and those with persistent symptoms of the complication. Mesh surgery imposes specific complications. When counseling patients about the potential adverse events related to vaginal mesh surgery, it is important to inform them that mesh-related complications do not negatively affect QoL related to micturition, defecation, and sexual functioning.

MeSHLabeler: improving the accuracy of large-scale MeSH indexing by integrating diverse evidence.

PubMed

Liu, Ke; Peng, Shengwen; Wu, Junqiu; Zhai, Chengxiang; Mamitsuka, Hiroshi; Zhu, Shanfeng

2015-06-15

Medical Subject Headings (MeSHs) are used by National Library of Medicine (NLM) to index almost all citations in MEDLINE, which greatly facilitates the applications of biomedical information retrieval and text mining. To reduce the time and financial cost of manual annotation, NLM has developed a software package, Medical Text Indexer (MTI), for assisting MeSH annotation, which uses k-nearest neighbors (KNN), pattern matching and indexing rules. Other types of information, such as prediction by MeSH classifiers (trained separately), can also be used for automatic MeSH annotation. However, existing methods cannot effectively integrate multiple evidence for MeSH annotation. We propose a novel framework, MeSHLabeler, to integrate multiple evidence for accurate MeSH annotation by using 'learning to rank'. Evidence includes numerous predictions from MeSH classifiers, KNN, pattern matching, MTI and the correlation between different MeSH terms, etc. Each MeSH classifier is trained independently, and thus prediction scores from different classifiers are incomparable. To address this issue, we have developed an effective score normalization procedure to improve the prediction accuracy. MeSHLabeler won the first place in Task 2A of 2014 BioASQ challenge, achieving the Micro F-measure of 0.6248 for 9,040 citations provided by the BioASQ challenge. Note that this accuracy is around 9.15% higher than 0.5724, obtained by MTI. The software is available upon request. © The Author 2015. Published by Oxford University Press.

MeSHLabeler: improving the accuracy of large-scale MeSH indexing by integrating diverse evidence

PubMed Central

Liu, Ke; Peng, Shengwen; Wu, Junqiu; Zhai, Chengxiang; Mamitsuka, Hiroshi; Zhu, Shanfeng

2015-01-01

Motivation: Medical Subject Headings (MeSHs) are used by National Library of Medicine (NLM) to index almost all citations in MEDLINE, which greatly facilitates the applications of biomedical information retrieval and text mining. To reduce the time and financial cost of manual annotation, NLM has developed a software package, Medical Text Indexer (MTI), for assisting MeSH annotation, which uses k-nearest neighbors (KNN), pattern matching and indexing rules. Other types of information, such as prediction by MeSH classifiers (trained separately), can also be used for automatic MeSH annotation. However, existing methods cannot effectively integrate multiple evidence for MeSH annotation. Methods: We propose a novel framework, MeSHLabeler, to integrate multiple evidence for accurate MeSH annotation by using ‘learning to rank’. Evidence includes numerous predictions from MeSH classifiers, KNN, pattern matching, MTI and the correlation between different MeSH terms, etc. Each MeSH classifier is trained independently, and thus prediction scores from different classifiers are incomparable. To address this issue, we have developed an effective score normalization procedure to improve the prediction accuracy. Results: MeSHLabeler won the first place in Task 2A of 2014 BioASQ challenge, achieving the Micro F-measure of 0.6248 for 9,040 citations provided by the BioASQ challenge. Note that this accuracy is around 9.15% higher than 0.5724, obtained by MTI. Availability and implementation: The software is available upon request. Contact: zhusf@fudan.edu.cn PMID:26072501

Local Refinement of Analysis-Suitable T-splines

DTIC Science & Technology

2011-03-01

3.2. The extension graph Intersecting T-junction extensions in an extended T-mesh Text can be visualized using an undirected graph . We call this graph ...the extension graph and denote it by E(Text). Each node in E corresponds to a single T-junction extension in Text. If two extensions in Text...intersect then an edge is drawn between the corresponding nodes in E. The extension graph for the extended T-mesh in Figure 7b is shown in Figure 8a. In this

MeSH indexing based on automatically generated summaries

PubMed Central

2013-01-01

Background MEDLINE citations are manually indexed at the U.S. National Library of Medicine (NLM) using as reference the Medical Subject Headings (MeSH) controlled vocabulary. For this task, the human indexers read the full text of the article. Due to the growth of MEDLINE, the NLM Indexing Initiative explores indexing methodologies that can support the task of the indexers. Medical Text Indexer (MTI) is a tool developed by the NLM Indexing Initiative to provide MeSH indexing recommendations to indexers. Currently, the input to MTI is MEDLINE citations, title and abstract only. Previous work has shown that using full text as input to MTI increases recall, but decreases precision sharply. We propose using summaries generated automatically from the full text for the input to MTI to use in the task of suggesting MeSH headings to indexers. Summaries distill the most salient information from the full text, which might increase the coverage of automatic indexing approaches based on MEDLINE. We hypothesize that if the results were good enough, manual indexers could possibly use automatic summaries instead of the full texts, along with the recommendations of MTI, to speed up the process while maintaining high quality of indexing results. Results We have generated summaries of different lengths using two different summarizers, and evaluated the MTI indexing on the summaries using different algorithms: MTI, individual MTI components, and machine learning. The results are compared to those of full text articles and MEDLINE citations. Our results show that automatically generated summaries achieve similar recall but higher precision compared to full text articles. Compared to MEDLINE citations, summaries achieve higher recall but lower precision. Conclusions Our results show that automatic summaries produce better indexing than full text articles. Summaries produce similar recall to full text but much better precision, which seems to indicate that automatic summaries can efficiently capture the most important contents within the original articles. The combination of MEDLINE citations and automatically generated summaries could improve the recommendations suggested by MTI. On the other hand, indexing performance might be dependent on the MeSH heading being indexed. Summarization techniques could thus be considered as a feature selection algorithm that might have to be tuned individually for each MeSH heading. PMID:23802936

Detecting experimental techniques and selecting relevant documents for protein-protein interactions from biomedical literature.

PubMed

Wang, Xinglong; Rak, Rafal; Restificar, Angelo; Nobata, Chikashi; Rupp, C J; Batista-Navarro, Riza Theresa B; Nawaz, Raheel; Ananiadou, Sophia

2011-10-03

The selection of relevant articles for curation, and linking those articles to experimental techniques confirming the findings became one of the primary subjects of the recent BioCreative III contest. The contest's Protein-Protein Interaction (PPI) task consisted of two sub-tasks: Article Classification Task (ACT) and Interaction Method Task (IMT). ACT aimed to automatically select relevant documents for PPI curation, whereas the goal of IMT was to recognise the methods used in experiments for identifying the interactions in full-text articles. We proposed and compared several classification-based methods for both tasks, employing rich contextual features as well as features extracted from external knowledge sources. For IMT, a new method that classifies pair-wise relations between every text phrase and candidate interaction method obtained promising results with an F1 score of 64.49%, as tested on the task's development dataset. We also explored ways to combine this new approach and more conventional, multi-label document classification methods. For ACT, our classifiers exploited automatically detected named entities and other linguistic information. The evaluation results on the BioCreative III PPI test datasets showed that our systems were very competitive: one of our IMT methods yielded the best performance among all participants, as measured by F1 score, Matthew's Correlation Coefficient and AUC iP/R; whereas for ACT, our best classifier was ranked second as measured by AUC iP/R, and also competitive according to other metrics. Our novel approach that converts the multi-class, multi-label classification problem to a binary classification problem showed much promise in IMT. Nevertheless, on the test dataset the best performance was achieved by taking the union of the output of this method and that of a multi-class, multi-label document classifier, which indicates that the two types of systems complement each other in terms of recall. For ACT, our system exploited a rich set of features and also obtained encouraging results. We examined the features with respect to their contributions to the classification results, and concluded that contextual words surrounding named entities, as well as the MeSH headings associated with the documents were among the main contributors to the performance.

Acoustic Response of Underwater Munitions near a Sediment Interface: Measurement Model Comparisons and Classification Schemes

DTIC Science & Technology

2015-04-23

12 Figure 4. Pulse- compressed baseband signals for sequence 40 from TREX13 …… 13 Figure 5. SAS image for sequence 40 from TREX13...12 meshes with data …………… 28 Figure 14. FE simulations for aluminum and steel replicas of an 100-mm UXO …… 28 Figure 15. FE meshes for two targets...PCB Pulse- compressed and baseband PC SWAT Personal Computer Shallow Water Acoustic Toolset PondEx09 Pond Experiment 2009 PondEx10 Pond Experiment

Retrieval feedback in MEDLINE.

PubMed Central

Srinivasan, P

1996-01-01

OBJECTIVE: To investigate a new approach for query expansion based on retrieval feedback. The first objective in this study was to examine alternative query-expansion methods within the same retrieval-feedback framework. The three alternatives proposed are: expansion on the MeSH query field alone, expansion on the free-text field alone, and expansion on both the MeSH and the free-text fields. The second objective was to gain further understanding of retrieval feedback by examining possible dependencies on relevant documents during the feedback cycle. DESIGN: Comparative study of retrieval effectiveness using the original unexpanded and the alternative expanded user queries on a MEDLINE test collection of 75 queries and 2,334 MEDLINE citations. MEASUREMENTS: Retrieval effectivenesses of the original unexpanded and the alternative expanded queries were compared using 11-point-average precision scores (11-AvgP). These are averages of precision scores obtained at 11 standard recall points. RESULTS: All three expansion strategies significantly improved the original queries in terms of retrieval effectiveness. Expansion on MeSH alone was equivalent to expansion on both MeSH and the free-text fields. Expansion on the free-text field alone improved the queries significantly less than did the other two strategies. The second part of the study indicated that retrieval-feedback-based expansion yields significant performance improvements independent of the availability of relevant documents for feedback information. CONCLUSIONS: Retrieval feedback offers a robust procedure for query expansion that is most effective for MEDLINE when applied to the MeSH field. PMID:8653452

An Experiment Comparing Lexical and Statistical Methods for Extracting MeSH Terms from Clinical Free Text

PubMed Central

Cooper, Gregory F.; Miller, Randolph A.

1998-01-01

Abstract Objective: A primary goal of the University of Pittsburgh's 1990-94 UMLS-sponsored effort was to develop and evaluate PostDoc (a lexical indexing system) and Pindex (a statistical indexing system) comparatively, and then in combination as a hybrid system. Each system takes as input a portion of the free text from a narrative part of a patient's electronic medical record and returns a list of suggested MeSH terms to use in formulating a Medline search that includes concepts in the text. This paper describes the systems and reports an evaluation. The intent is for this evaluation to serve as a step toward the eventual realization of systems that assist healthcare personnel in using the electronic medical record to construct patient-specific searches of Medline. Design: The authors tested the performances of PostDoc, Pindex, and a hybrid system, using text taken from randomly selected clinical records, which were stratified to include six radiology reports, six pathology reports, and six discharge summaries. They identified concepts in the clinical records that might conceivably be used in performing a patient-specific Medline search. Each system was given the free text of each record as an input. The extent to which a system-derived list of MeSH terms captured the relevant concepts in these documents was determined based on blinded assessments by the authors. Results: PostDoc output a mean of approximately 19 MeSH terms per report, which included about 40% of the relevant report concepts. Pindex output a mean of approximately 57 terms per report and captured about 45% of the relevant report concepts. A hybrid system captured approximately 66% of the relevant concepts and output about 71 terms per report. Conclusion: The outputs of PostDoc and Pindex are complementary in capturing MeSH terms from clinical free text. The results suggest possible approaches to reduce the number of terms output while maintaining the percentage of terms captured, including the use of UMLS semantic types to constrain the output list to contain only clinically relevant MeSH terms. PMID:9452986

European Hernia Society guidelines on prevention and treatment of parastomal hernias.

PubMed

Antoniou, S A; Agresta, F; Garcia Alamino, J M; Berger, D; Berrevoet, F; Brandsma, H-T; Bury, K; Conze, J; Cuccurullo, D; Dietz, U A; Fortelny, R H; Frei-Lanter, C; Hansson, B; Helgstrand, F; Hotouras, A; Jänes, A; Kroese, L F; Lambrecht, J R; Kyle-Leinhase, I; López-Cano, M; Maggiori, L; Mandalà, V; Miserez, M; Montgomery, A; Morales-Conde, S; Prudhomme, M; Rautio, T; Smart, N; Śmietański, M; Szczepkowski, M; Stabilini, C; Muysoms, F E

2018-02-01

International guidelines on the prevention and treatment of parastomal hernias are lacking. The European Hernia Society therefore implemented a Clinical Practice Guideline development project. The guidelines development group consisted of general, hernia and colorectal surgeons, a biostatistician and a biologist, from 14 European countries. These guidelines conformed to the AGREE II standards and the GRADE methodology. The databases of MEDLINE, CINAHL, CENTRAL and the gray literature through OpenGrey were searched. Quality assessment was performed using Scottish Intercollegiate Guidelines Network checklists. The guidelines were presented at the 38th European Hernia Society Congress and each key question was evaluated in a consensus voting of congress participants. End colostomy is associated with a higher incidence of parastomal hernia, compared to other types of stomas. Clinical examination is necessary for the diagnosis of parastomal hernia, whereas computed tomography scan or ultrasonography may be performed in cases of diagnostic uncertainty. Currently available classifications are not validated; however, we suggest the use of the European Hernia Society classification for uniform research reporting. There is insufficient evidence on the policy of watchful waiting, the route and location of stoma construction, and the size of the aperture. The use of a prophylactic synthetic non-absorbable mesh upon construction of an end colostomy is strongly recommended. No such recommendation can be made for other types of stomas at present. It is strongly recommended to avoid performing a suture repair for elective parastomal hernia. So far, there is no sufficient comparative evidence on specific techniques, open or laparoscopic surgery and specific mesh types. However, a mesh without a hole is suggested in preference to a keyhole mesh when laparoscopic repair is performed. An evidence-based approach to the diagnosis and management of parastomal hernias reveals the lack of evidence on several topics, which need to be addressed by multicenter trials. Parastomal hernia prevention using a prophylactic mesh for end colostomies reduces parastomal herniation. Clinical outcomes should be audited and adverse events must be reported.

Evaluation and management of complications from synthetic mesh after pelvic reconstructive surgery: a multicenter study.

PubMed

Abbott, Sara; Unger, Cecile A; Evans, Janelle M; Jallad, Karl; Mishra, Kevita; Karram, Mickey M; Iglesia, Cheryl B; Rardin, Charles R; Barber, Matthew D

2014-02-01

The purpose of this study was to describe the evaluation and management of synthetic mesh-related complications after surgery for stress urinary incontinence (SUI) and/or pelvic organ prolapse (POP). We conducted a multicenter, retrospective analysis of women who attended 4 US tertiary referral centers for evaluation of mesh-related complications after surgery for SUI and/or POP from January 2006 to December 2010. Demographic, clinical, and surgical data were abstracted from the medical record, and complications were classified according to the Expanded Accordion Severity Classification. Three hundred forty-seven patients sought management of synthetic mesh-related complications over the study period. Index surgeries were performed for the following indications: SUI (sling only), 49.9%; POP (transvaginal mesh [TVM] or sacrocolpopexy only), 25.6%; and SUI + POP (sling + TVM or sacrocolpopexy), 24.2%. Median time to evaluation was 5.8 months (range, 0-65.2). Thirty percent of the patients had dyspareunia; 42.7% of the patients had mesh erosion; and 34.6% of the patients had pelvic pain. Seventy-seven percent of the patients had a grade 3 or 4 (severe) complication. Patients with TVM or sacrocolpopexy were more likely to have mesh erosion and vaginal symptoms compared with sling only. The median number of treatments for mesh complications was 2 (range, 1-9); 60% of the women required ≥2 interventions. Initial treatment intervention was surgical for 49% of subjects. Of those treatments that initially were managed nonsurgically, 59.3% went on to surgical intervention. Most of the women who seek management of synthetic mesh complication after POP or SUI surgery have severe complications that require surgical intervention; a significant proportion require >1 surgical procedure. The pattern of complaints differs by index procedure. Copyright © 2014 Mosby, Inc. All rights reserved.

Deep Learning Applications for Predicting Pharmacological Properties of Drugs and Drug Repurposing Using Transcriptomic Data.

PubMed

Aliper, Alexander; Plis, Sergey; Artemov, Artem; Ulloa, Alvaro; Mamoshina, Polina; Zhavoronkov, Alex

2016-07-05

Deep learning is rapidly advancing many areas of science and technology with multiple success stories in image, text, voice and video recognition, robotics, and autonomous driving. In this paper we demonstrate how deep neural networks (DNN) trained on large transcriptional response data sets can classify various drugs to therapeutic categories solely based on their transcriptional profiles. We used the perturbation samples of 678 drugs across A549, MCF-7, and PC-3 cell lines from the LINCS Project and linked those to 12 therapeutic use categories derived from MeSH. To train the DNN, we utilized both gene level transcriptomic data and transcriptomic data processed using a pathway activation scoring algorithm, for a pooled data set of samples perturbed with different concentrations of the drug for 6 and 24 hours. In both pathway and gene level classification, DNN achieved high classification accuracy and convincingly outperformed the support vector machine (SVM) model on every multiclass classification problem, however, models based on pathway level data performed significantly better. For the first time we demonstrate a deep learning neural net trained on transcriptomic data to recognize pharmacological properties of multiple drugs across different biological systems and conditions. We also propose using deep neural net confusion matrices for drug repositioning. This work is a proof of principle for applying deep learning to drug discovery and development.

Deep learning applications for predicting pharmacological properties of drugs and drug repurposing using transcriptomic data

PubMed Central

Aliper, Alexander; Plis, Sergey; Artemov, Artem; Ulloa, Alvaro; Mamoshina, Polina; Zhavoronkov, Alex

2016-01-01

Deep learning is rapidly advancing many areas of science and technology with multiple success stories in image, text, voice and video recognition, robotics and autonomous driving. In this paper we demonstrate how deep neural networks (DNN) trained on large transcriptional response data sets can classify various drugs to therapeutic categories solely based on their transcriptional profiles. We used the perturbation samples of 678 drugs across A549, MCF‐7 and PC‐3 cell lines from the LINCS project and linked those to 12 therapeutic use categories derived from MeSH. To train the DNN, we utilized both gene level transcriptomic data and transcriptomic data processed using a pathway activation scoring algorithm, for a pooled dataset of samples perturbed with different concentrations of the drug for 6 and 24 hours. In both gene and pathway level classification, DNN convincingly outperformed support vector machine (SVM) model on every multiclass classification problem, however, models based on a pathway level classification perform better. For the first time we demonstrate a deep learning neural net trained on transcriptomic data to recognize pharmacological properties of multiple drugs across different biological systems and conditions. We also propose using deep neural net confusion matrices for drug repositioning. This work is a proof of principle for applying deep learning to drug discovery and development. PMID:27200455

Detecting experimental techniques and selecting relevant documents for protein-protein interactions from biomedical literature

PubMed Central

2011-01-01

Background The selection of relevant articles for curation, and linking those articles to experimental techniques confirming the findings became one of the primary subjects of the recent BioCreative III contest. The contest’s Protein-Protein Interaction (PPI) task consisted of two sub-tasks: Article Classification Task (ACT) and Interaction Method Task (IMT). ACT aimed to automatically select relevant documents for PPI curation, whereas the goal of IMT was to recognise the methods used in experiments for identifying the interactions in full-text articles. Results We proposed and compared several classification-based methods for both tasks, employing rich contextual features as well as features extracted from external knowledge sources. For IMT, a new method that classifies pair-wise relations between every text phrase and candidate interaction method obtained promising results with an F1 score of 64.49%, as tested on the task’s development dataset. We also explored ways to combine this new approach and more conventional, multi-label document classification methods. For ACT, our classifiers exploited automatically detected named entities and other linguistic information. The evaluation results on the BioCreative III PPI test datasets showed that our systems were very competitive: one of our IMT methods yielded the best performance among all participants, as measured by F1 score, Matthew’s Correlation Coefficient and AUC iP/R; whereas for ACT, our best classifier was ranked second as measured by AUC iP/R, and also competitive according to other metrics. Conclusions Our novel approach that converts the multi-class, multi-label classification problem to a binary classification problem showed much promise in IMT. Nevertheless, on the test dataset the best performance was achieved by taking the union of the output of this method and that of a multi-class, multi-label document classifier, which indicates that the two types of systems complement each other in terms of recall. For ACT, our system exploited a rich set of features and also obtained encouraging results. We examined the features with respect to their contributions to the classification results, and concluded that contextual words surrounding named entities, as well as the MeSH headings associated with the documents were among the main contributors to the performance. PMID:22151769

An overview of the BIOASQ large-scale biomedical semantic indexing and question answering competition.

PubMed

Tsatsaronis, George; Balikas, Georgios; Malakasiotis, Prodromos; Partalas, Ioannis; Zschunke, Matthias; Alvers, Michael R; Weissenborn, Dirk; Krithara, Anastasia; Petridis, Sergios; Polychronopoulos, Dimitris; Almirantis, Yannis; Pavlopoulos, John; Baskiotis, Nicolas; Gallinari, Patrick; Artiéres, Thierry; Ngomo, Axel-Cyrille Ngonga; Heino, Norman; Gaussier, Eric; Barrio-Alvers, Liliana; Schroeder, Michael; Androutsopoulos, Ion; Paliouras, Georgios

2015-04-30

This article provides an overview of the first BIOASQ challenge, a competition on large-scale biomedical semantic indexing and question answering (QA), which took place between March and September 2013. BIOASQ assesses the ability of systems to semantically index very large numbers of biomedical scientific articles, and to return concise and user-understandable answers to given natural language questions by combining information from biomedical articles and ontologies. The 2013 BIOASQ competition comprised two tasks, Task 1a and Task 1b. In Task 1a participants were asked to automatically annotate new PUBMED documents with MESH headings. Twelve teams participated in Task 1a, with a total of 46 system runs submitted, and one of the teams performing consistently better than the MTI indexer used by NLM to suggest MESH headings to curators. Task 1b used benchmark datasets containing 29 development and 282 test English questions, along with gold standard (reference) answers, prepared by a team of biomedical experts from around Europe and participants had to automatically produce answers. Three teams participated in Task 1b, with 11 system runs. The BIOASQ infrastructure, including benchmark datasets, evaluation mechanisms, and the results of the participants and baseline methods, is publicly available. A publicly available evaluation infrastructure for biomedical semantic indexing and QA has been developed, which includes benchmark datasets, and can be used to evaluate systems that: assign MESH headings to published articles or to English questions; retrieve relevant RDF triples from ontologies, relevant articles and snippets from PUBMED Central; produce "exact" and paragraph-sized "ideal" answers (summaries). The results of the systems that participated in the 2013 BIOASQ competition are promising. In Task 1a one of the systems performed consistently better from the NLM's MTI indexer. In Task 1b the systems received high scores in the manual evaluation of the "ideal" answers; hence, they produced high quality summaries as answers. Overall, BIOASQ helped obtain a unified view of how techniques from text classification, semantic indexing, document and passage retrieval, question answering, and text summarization can be combined to allow biomedical experts to obtain concise, user-understandable answers to questions reflecting their real information needs.

Encoding the local connectivity patterns of fMRI for cognitive task and state classification.

PubMed

Onal Ertugrul, Itir; Ozay, Mete; Yarman Vural, Fatos T

2018-06-15

In this work, we propose a novel framework to encode the local connectivity patterns of brain, using Fisher vectors (FV), vector of locally aggregated descriptors (VLAD) and bag-of-words (BoW) methods. We first obtain local descriptors, called mesh arc descriptors (MADs) from fMRI data, by forming local meshes around anatomical regions, and estimating their relationship within a neighborhood. Then, we extract a dictionary of relationships, called brain connectivity dictionary by fitting a generative Gaussian mixture model (GMM) to a set of MADs, and selecting codewords at the mean of each component of the mixture. Codewords represent connectivity patterns among anatomical regions. We also encode MADs by VLAD and BoW methods using k-Means clustering. We classify cognitive tasks using the Human Connectome Project (HCP) task fMRI dataset and cognitive states using the Emotional Memory Retrieval (EMR). We train support vector machines (SVMs) using the encoded MADs. Results demonstrate that, FV encoding of MADs can be successfully employed for classification of cognitive tasks, and outperform VLAD and BoW representations. Moreover, we identify the significant Gaussians in mixture models by computing energy of their corresponding FV parts, and analyze their effect on classification accuracy. Finally, we suggest a new method to visualize the codewords of the learned brain connectivity dictionary.

MAC layer security issues in wireless mesh networks

NASA Astrophysics Data System (ADS)

Reddy, K. Ganesh; Thilagam, P. Santhi

2016-03-01

Wireless Mesh Networks (WMNs) have emerged as a promising technology for a broad range of applications due to their self-organizing, self-configuring and self-healing capability, in addition to their low cost and easy maintenance. Securing WMNs is more challenging and complex issue due to their inherent characteristics such as shared wireless medium, multi-hop and inter-network communication, highly dynamic network topology and decentralized architecture. These vulnerable features expose the WMNs to several types of attacks in MAC layer. The existing MAC layer standards and implementations are inadequate to secure these features and fail to provide comprehensive security solutions to protect both backbone and client mesh. Hence, there is a need for developing efficient, scalable and integrated security solutions for WMNs. In this paper, we classify the MAC layer attacks and analyze the existing countermeasures. Based on attacks classification and countermeasures analysis, we derive the research directions to enhance the MAC layer security for WMNs.

Comparison and combination of several MeSH indexing approaches

PubMed Central

Yepes, Antonio Jose Jimeno; Mork, James G.; Demner-Fushman, Dina; Aronson, Alan R.

2013-01-01

MeSH indexing of MEDLINE is becoming a more difficult task for the group of highly qualified indexing staff at the US National Library of Medicine, due to the large yearly growth of MEDLINE and the increasing size of MeSH. Since 2002, this task has been assisted by the Medical Text Indexer or MTI program. We extend previous machine learning analysis by adding a more diverse set of MeSH headings targeting examples where MTI has been shown to perform poorly. Machine learning algorithms exceed MTI’s performance on MeSH headings that are used very frequently and headings for which the indexing frequency is very low. We find that when we combine the MTI suggestions and the prediction of the learning algorithms, the performance improves compared to any single method for most of the evaluated MeSH headings. PMID:24551371

Comparison and combination of several MeSH indexing approaches.

PubMed

Yepes, Antonio Jose Jimeno; Mork, James G; Demner-Fushman, Dina; Aronson, Alan R

2013-01-01

MeSH indexing of MEDLINE is becoming a more difficult task for the group of highly qualified indexing staff at the US National Library of Medicine, due to the large yearly growth of MEDLINE and the increasing size of MeSH. Since 2002, this task has been assisted by the Medical Text Indexer or MTI program. We extend previous machine learning analysis by adding a more diverse set of MeSH headings targeting examples where MTI has been shown to perform poorly. Machine learning algorithms exceed MTI's performance on MeSH headings that are used very frequently and headings for which the indexing frequency is very low. We find that when we combine the MTI suggestions and the prediction of the learning algorithms, the performance improves compared to any single method for most of the evaluated MeSH headings.

Using UMLS to map from a library to a clinical classification: Improving the functionality of a digital library.

PubMed

Robinson, Judas; de Lusignan, Simon; Kostkova, Patty; Madge, Bruce

2006-01-01

The Metathesaurus of the Unified Medical Language System (UMLS) offers the possibility of mapping between various medical vocabularies. The Primary Care Electronic Library (PCEL) contains a database of over six thousand Medical Subject Headings (MeSH terms) describing the resources of the electronic library. We were interested to know if it was possible to map from MeSH to the Systemized Nomenclature of Medicine Clinical Terms (SNOMED CT). Such a mapping would aid healthcare professionals to retrieve relevant data from our digital library as it would enable links between clinical systems and indexed material.

29 CFR 1910.184 - Slings.

Code of Federal Regulations, 2010 CFR

2010-07-01

... alloy steel chain, wire rope, metal mesh, natural or synthetic fiber rope (conventional three strand... steel chain sling or wire rope sling. (See Fig. N-184-3.) Mechanical coupling link is a nonwelded... Slings 6×19 and 6×37 Classification Improved Plow Steel Grade Rope With Independent Wire Rope Core (IWRC...

29 CFR 1910.184 - Slings.

Code of Federal Regulations, 2011 CFR

2011-07-01

... alloy steel chain, wire rope, metal mesh, natural or synthetic fiber rope (conventional three strand... steel chain sling or wire rope sling. (See Fig. N-184-3.) Mechanical coupling link is a nonwelded... Slings 6×19 and 6×37 Classification Improved Plow Steel Grade Rope With Independent Wire Rope Core (IWRC...

Proposal and validation of a new model to estimate survival for hepatocellular carcinoma patients.

PubMed

Liu, Po-Hong; Hsu, Chia-Yang; Hsia, Cheng-Yuan; Lee, Yun-Hsuan; Huang, Yi-Hsiang; Su, Chien-Wei; Lee, Fa-Yauh; Lin, Han-Chieh; Huo, Teh-Ia

2016-08-01

The survival of hepatocellular carcinoma (HCC) patients is heterogeneous. We aim to develop and validate a simple prognostic model to estimate survival for HCC patients (MESH score). A total of 3182 patients were randomised into derivation and validation cohort. Multivariate analysis was used to identify independent predictors of survival in the derivation cohort. The validation cohort was employed to examine the prognostic capabilities. The MESH score allocated 1 point for each of the following parameters: large tumour (beyond Milan criteria), presence of vascular invasion or metastasis, Child-Turcotte-Pugh score ≥6, performance status ≥2, serum alpha-fetoprotein level ≥20 ng/ml, and serum alkaline phosphatase ≥200 IU/L, with a maximal of 6 points. In the validation cohort, significant survival differences were found across all MESH scores from 0 to 6 (all p < 0.01). The MESH system was associated with the highest homogeneity and lowest corrected Akaike information criterion compared with Barcelona Clínic Liver Cancer, Hong Kong Liver Cancer (HKLC), Cancer of the Liver Italian Program, Taipei Integrated Scoring and model to estimate survival in ambulatory HCC Patients systems. The prognostic accuracy of the MESH scores remained constant in patients with hepatitis B- or hepatitis C-related HCC. The MESH score can also discriminate survival for patients from early to advanced stages of HCC. This newly proposed simple and accurate survival model provides enhanced prognostic accuracy for HCC. The MESH system is a useful supplement to the BCLC and HKLC classification schemes in refining treatment strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Feature engineering for MEDLINE citation categorization with MeSH.

PubMed

Jimeno Yepes, Antonio Jose; Plaza, Laura; Carrillo-de-Albornoz, Jorge; Mork, James G; Aronson, Alan R

2015-04-08

Research in biomedical text categorization has mostly used the bag-of-words representation. Other more sophisticated representations of text based on syntactic, semantic and argumentative properties have been less studied. In this paper, we evaluate the impact of different text representations of biomedical texts as features for reproducing the MeSH annotations of some of the most frequent MeSH headings. In addition to unigrams and bigrams, these features include noun phrases, citation meta-data, citation structure, and semantic annotation of the citations. Traditional features like unigrams and bigrams exhibit strong performance compared to other feature sets. Little or no improvement is obtained when using meta-data or citation structure. Noun phrases are too sparse and thus have lower performance compared to more traditional features. Conceptual annotation of the texts by MetaMap shows similar performance compared to unigrams, but adding concepts from the UMLS taxonomy does not improve the performance of using only mapped concepts. The combination of all the features performs largely better than any individual feature set considered. In addition, this combination improves the performance of a state-of-the-art MeSH indexer. Concerning the machine learning algorithms, we find that those that are more resilient to class imbalance largely obtain better performance. We conclude that even though traditional features such as unigrams and bigrams have strong performance compared to other features, it is possible to combine them to effectively improve the performance of the bag-of-words representation. We have also found that the combination of the learning algorithm and feature sets has an influence in the overall performance of the system. Moreover, using learning algorithms resilient to class imbalance largely improves performance. However, when using a large set of features, consideration needs to be taken with algorithms due to the risk of over-fitting. Specific combinations of learning algorithms and features for individual MeSH headings could further increase the performance of an indexing system.

Automated confidence ranked classification of randomized controlled trial articles: an aid to evidence-based medicine

PubMed Central

Smalheiser, Neil R; McDonagh, Marian S; Yu, Clement; Adams, Clive E; Davis, John M; Yu, Philip S

2015-01-01

Objective: For many literature review tasks, including systematic review (SR) and other aspects of evidence-based medicine, it is important to know whether an article describes a randomized controlled trial (RCT). Current manual annotation is not complete or flexible enough for the SR process. In this work, highly accurate machine learning predictive models were built that include confidence predictions of whether an article is an RCT. Materials and Methods: The LibSVM classifier was used with forward selection of potential feature sets on a large human-related subset of MEDLINE to create a classification model requiring only the citation, abstract, and MeSH terms for each article. Results: The model achieved an area under the receiver operating characteristic curve of 0.973 and mean squared error of 0.013 on the held out year 2011 data. Accurate confidence estimates were confirmed on a manually reviewed set of test articles. A second model not requiring MeSH terms was also created, and performs almost as well. Discussion: Both models accurately rank and predict article RCT confidence. Using the model and the manually reviewed samples, it is estimated that about 8000 (3%) additional RCTs can be identified in MEDLINE, and that 5% of articles tagged as RCTs in Medline may not be identified. Conclusion: Retagging human-related studies with a continuously valued RCT confidence is potentially more useful for article ranking and review than a simple yes/no prediction. The automated RCT tagging tool should offer significant savings of time and effort during the process of writing SRs, and is a key component of a multistep text mining pipeline that we are building to streamline SR workflow. In addition, the model may be useful for identifying errors in MEDLINE publication types. The RCT confidence predictions described here have been made available to users as a web service with a user query form front end at: http://arrowsmith.psych.uic.edu/cgi-bin/arrowsmith_uic/RCT_Tagger.cgi. PMID:25656516

Interobserver variability when employing the IUGA/ICS classification system for complications related to prostheses and grafts in female pelvic floor surgery.

PubMed

Gowda, Meghana; Kit, Laura Chang; Stuart Reynolds, W; Wang, Li; Dmochowski, Roger R; Kaufman, Melissa R

2013-10-01

To unify and organize reporting, an International Urogynecological Association (IUGA)/International Continence Society (ICS) expert consortium published terminology guidelines with a classification system for complications related to implants used in female pelvic surgery. We hypothesize that the complexity of the codification system may be a hindrance to precision, especially with decreasing levels of postgraduate expertise. Residents, fellows, and attending physicians were asked to code seven test cases taken from published literature. Category, timing, and site components of the classification system were assessed independently and according to the level of training. Interobserver reliability was calculated as percent agreement and Fleiss' kappa statistic. A total of 24 participants (6 attending physicians, 3 fellows, and 15 residents) were tested. The percent agreement showed significant variation when classified by level of training. In all categories, attending physicians had the greatest percentage agreement and largest kappa. The most agreement was seen when attending physicians classified mesh complications by time, 71% agreement with kappa 0.73 [95% confidence interval (CI) 0.58-0.88]. For the same task, the percentage agreement for fellows was 57%, kappa 0.55 (95% CI 0.23-0.87) and with residents 57%, kappa 0.71([95% CI 0.64-0.78). Interestingly, the site component of the classification system had the least overall agreement and lowest kappa [0%, kappa 0.29 (95% CI 0.26-0.32)] followed by the category component [14%, kappa 0.48 (95% CI 0.46-0.5)]. The IUGA/ICS mesh complication classification system has poor interobserver reliability. This trended downward with decreasing postgraduate level; however, we did not have sufficient statistical power to show an association when stratifying by all training levels. This highlights the complex nature of the classification system in its current form and its limitation for widespread clinical and research application.

Information content in Medline record fields.

PubMed

Kostoff, Ronald N; Block, Joel A; Stump, Jesse A; Pfeil, Kirstin M

2004-06-30

The authors have been conducting text mining analyses (extraction of useful information from text) of Medline records, using Abstracts as the main data source. For literature-based discovery, and other text mining applications as well, all records in a discipline need to be evaluated for determining prior art. Many Medline records do not contain Abstracts, but typically contain Titles and Mesh terms. Substitution of these fields for Abstracts in the non-Abstract records would restore the missing literature to some degree. Determine how well the information content of Title and Mesh fields approximates that of Abstracts in Medline records. Select historical Medline records related to Raynaud's Phenomenon that contain Abstracts. Determine the information content in the Abstract fields through text mining. Then, determine the information content in the Title fields, the Mesh fields, and the combined Title-Mesh fields, and compare with the information content in the Abstracts. Four metrics were used to compare the information content related to Raynaud's Phenomenon in the different fields: total number of phrases; number of unique phrases; content of factors from factor analyses; content of clusters from multi-link clustering. The Abstract field contains almost an order of magnitude more phrases than the other fields, and slightly more than an order of magnitude more unique phrases than the other fields. Each field used a factor matrix with 14 factors, and the combination of all 56 factors for the four fields represented 27 separate, but not unique, themes. These themes could be placed in two major categories, with two sub-categories per major category: Auto-immunity (antibodies, inflammation) and circulation (peripheral vessel circulation, coronary vessel circulation). All four sub-categories included representation from each field. Thus, while the focus of the representation of each field in each sub-category was moderately different, the four sub-category structure could be identified by analyzing the total factors in each field. In the cluster comparison phase of the study, the phrases used to create the clusters were the most important phrases identified for each factor. Thus, the factor matrix served as a filter for words used for clustering. While clusters were generated for all four fields, the Title hierarchy tended to be fragmented due to sparsity of the co-occurrence matrix that underlies the clusters. Therefore, the Title clusters were examined at only the lower levels of aggregation. The Abstract, Mesh, and Mesh + Title fields had the same first level taxonomy categories, auto-immunity and circulation. At the second level, the Abstract, Mesh, and Mesh + Title fields had the autoimmune diseases and antibodies sub-category in common. The Abstract and Mesh fields shared fascia inflammation as the other auto-immunity sub-category, while the other Mesh + Title sub-category focuses on vinyl chloride poisoning from industrial contact, and consequences of antineoplastic agents. However, in both cases, even though the words may be different, inflammation may be the common theme. For taxonomy generation, especially at the higher levels, each of the four fields has a similar thematic structure. At very detailed levels, the Mesh and Title fields run out of phrases relative to the Abstract field. Therefore, selection of field (s) to be employed for taxonomy generation depends on the objectives of the study, particularly the level of categorization required for the taxonomy. For information retrieval, or literature-based discovery, selection of the appropriate field again depends on the study objectives. If large queries, or large numbers of concepts or themes are desired, then the field with the largest number of technical phrases would be desirable. If queries or concepts represented by the more accepted popular terminology is adequate, then the smaller fields may be sufficient. Because of its established and controlled vocabulary, the Mesh field lags the Title or Abss the Title or Abstract fields in currency. Thus, the Title or Abstract fields would retrieve records with the most explicitly stated current concepts, but the Mesh field would capture a larger swath of fields that contained a concept of interest but perhaps had a wider range of specific terminology in the Abstract or Title text. In addition, this study provides the first validated estimate of the disparity in information retrieved through text mining limited to Titles and Mesh terms relative to entire Abstracts. As much of the older biomedical literature was entered into electronic databases without associated Abstracts, literature-based discovery exercises that search the older medical literature may miss a substantial proportion of relevant information. On the basis of this study, it may be estimated that up to a log order more information may be retrieved when complete Abstracts are searched.

Prosthetic Mesh Repair in the Emergency Management of Acutely Strangulated Groin Hernias with Grade I Bowel Necrosis: A Rational Choice.

PubMed

Duan, Sheng-Jun; Qiu, Shao-Bo; Ding, Nai-Yong; Liu, Hua-Shui; Zhang, Nai-Shun; Wei, Ying-Tian

2018-02-01

The aim of this study was to determine the feasibility of prosthetic mesh repair according to the degree of bowel necrosis in the emergency management of acutely strangulated groin hernias. Emergency prosthetic mesh repair versus primary suture repair was randomly performed in 208 consecutive strangulated groin hernia patients with bowel necrosis between January 2005 and August 2016. The degree of bowel necrosis of each patient was determined according to a modified three-grade classification system. Patient characteristics sorted by repair method were analyzed by using Pearson's chi-squared tests. Correlations between mortality and wound-related morbidity with bowel necrosis grade and repair method were analyzed. There was no difference in gender, age, body mass index, comorbid diseases, hernia type (left or right, primary or recurrent), necrosis grade, and mortality between the mesh repair and suture repair groups (all P > 0.05). However, with regard to wound-related morbidity, there was significant difference between the two groups (P < 0.05). Mortality and wound-related morbidity showed significant relationship with necrosis grade, especially with regard to postoperative wound infection (P < 0.001). The wound infection rate with mesh repair was significantly higher than that with primary suture in Grade II and III necrosis patients (P < 0.05), but there was no difference in Grade I patients (P > 0.05). The use of prosthetic mesh in the emergency repair of acutely strangulated groin hernias seems to be as safe as suture-only repair in patients with noninfected strangulated bowel (Grade I necrosis). The use of prosthetic mesh repair is a rational choice made based on the degree of bowel necrosis in the emergency management of acutely strangulated hernias.

Clinical observation of a modified surgical method: posterior vaginal mesh suspension of female rectocele with intractable constipation.

PubMed

Hong, Ling; Li, Huai-Fang; Sun, Jing; Zhu, Jian-Long; Ai, Gui-hai; Li, Li; Zhang, Bo; Chi, Feng-li; Tong, Xiao-Wen

2012-01-01

To explore the feasibility and effectiveness of a modified posterior vaginal mesh suspension method in treating female rectocele with intractable constipation. Descriptive study (Canadian Task Force classification II-3). The study was performed in the Study Center for Female Pelvic Dysfunction Disease, Department of Obstetrics and Gynecology, Tongji Hospital, Tongji University School of Medicine, Shanghai, China. The Study Center includes 15 physicians, most of whom have received advanced training in pelvic floor dysfunctional disease and can skillfully perform many types of operations in patients with such disease. Almost 1500 operations to treat pelvic floor dysfunctional disease are performed every year at the center. Thirty-six women with rectocele with intractable constipation. Posterior vaginal mesh suspension. All patients were followed up for 15 to 36 months. In 29 patients, the condition was cured completely; in 5 patients it had improved; and in 2 patients, the intervention had no effect. Insofar as recovery and improved results, the overall effectiveness rate was 94.4%. Posterior vaginal mesh suspension is an effective, harmless, and convenient method for treatment of female rectocele with intractable constipation. It has positive short-term curative effects, with few complications and sequelae. However, the long-term effects of posterior vaginal mesh suspension should be evaluated. Copyright © 2012 AAGL. Published by Elsevier Inc. All rights reserved.

Research on Classification of Chinese Text Data Based on SVM

NASA Astrophysics Data System (ADS)

Lin, Yuan; Yu, Hongzhi; Wan, Fucheng; Xu, Tao

2017-09-01

Data Mining has important application value in today’s industry and academia. Text classification is a very important technology in data mining. At present, there are many mature algorithms for text classification. KNN, NB, AB, SVM, decision tree and other classification methods all show good classification performance. Support Vector Machine’ (SVM) classification method is a good classifier in machine learning research. This paper will study the classification effect based on the SVM method in the Chinese text data, and use the support vector machine method in the chinese text to achieve the classify chinese text, and to able to combination of academia and practical application.

Meshable: searching PubMed abstracts by utilizing MeSH and MeSH-derived topical terms.

PubMed

Kim, Sun; Yeganova, Lana; Wilbur, W John

2016-10-01

Medical Subject Headings (MeSH(®)) is a controlled vocabulary for indexing and searching biomedical literature. MeSH terms and subheadings are organized in a hierarchical structure and are used to indicate the topics of an article. Biologists can use either MeSH terms as queries or the MeSH interface provided in PubMed(®) for searching PubMed abstracts. However, these are rarely used, and there is no convenient way to link standardized MeSH terms to user queries. Here, we introduce a web interface which allows users to enter queries to find MeSH terms closely related to the queries. Our method relies on co-occurrence of text words and MeSH terms to find keywords that are related to each MeSH term. A query is then matched with the keywords for MeSH terms, and candidate MeSH terms are ranked based on their relatedness to the query. The experimental results show that our method achieves the best performance among several term extraction approaches in terms of topic coherence. Moreover, the interface can be effectively used to find full names of abbreviations and to disambiguate user queries. https://www.ncbi.nlm.nih.gov/IRET/MESHABLE/ CONTACT: sun.kim@nih.gov Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

Outcomes of abdominal wall reconstruction with acellular dermal matrix are not affected by wound contamination.

PubMed

Garvey, Patrick B; Martinez, Roberto A; Baumann, Donald P; Liu, Jun; Butler, Charles E

2014-11-01

The optimal type of mesh for complex abdominal wall reconstruction has not been elucidated. We hypothesized that AWRs using acellular dermal matrix (ADM) experience low rates of surgical site occurrence (SSO) and surgical site infection, despite increasing degrees of wound contamination. We retrospectively reviewed prospectively collected data from consecutive abdominal wall reconstructions with ADM over a 9-year period. Outcomes of abdominal wall reconstructions were compared between patients with different CDC wound classifications. Univariate and multivariate logistic regression and Cox proportional hazard regression analyses identified potential associations and predictive/protective factors. The 359 patients had a mean follow-up of 28.3 ± 19.0 months. Reconstruction of clean wounds (n = 171) required fewer reoperations than that of combined contaminated (n = 188) wounds (2.3% vs 11.2%; p = 0.001) and trended toward experiencing fewer SSOs (19.9% vs 28.7%, p = 0.052). There were no significant differences between clean and combined contaminated cases in 30-day SSI (8.8% vs 8.0%), hernia recurrence (9.9% vs 10.1%), and mesh removal (1.2% vs 1.1%) rates. Independent predictors of SSO included body mass index ≥30 kg/m(2) (odds ratio [OR] 3.6; p < 0.001), 1 or more comorbidities (OR 2.5; p = 0.008), and defect width ≥15 cm (OR 1.8; p = 0.02). Complex abdominal wall reconstructions using ADM demonstrated similar rates of complications between the different CDC wound classifications. This is in contradistinction to published outcomes for abdominal wall reconstruction using synthetic mesh that show progressively higher complication rates with increasing degrees of contamination. These data support the use of ADM rather than synthetic mesh for complex abdominal wall reconstruction in the setting of wound contamination. Copyright © 2014 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Safety of Synthetic Glue Used for Laparoscopic Prolapse Treatment.

PubMed

Sarasa Castelló, Núria; Toth, Alexandra; Canis, Michel; Botchorishvilli, Revaz

2017-12-29

We detected mesh erosion and serious postoperative complications in 3 women after performing laparoscopic promontofixation (LPF) using glue for mesh fixation. Glue, largely used in hernia surgery repair, is proposed by some gynecologic surgeons because it saves time and is easier to use than traditional sutures. We report 3 cases of postoperative complications after LPF in which glue had been used and provide research in the published literature about the use of glue in LPF. A research of glue use in gynecology mesh fixation was performed through PubMed on October 2016. The search was done using the Medical Subject Heading terms "POP" & "Laparoscopy" & "surgical Mesh" and the word either "glue" or "adhesive. Only 2 articles were found: Willecocq et al [1] and Estrade et al [2]. Neither study focused on postoperative complications. In this publication, we accurately edited video surgeries with an instructive purpose. University Hospital of Clermont-Ferrand, France. Patient A, a 65-year-old woman, complained of pelvic pain and vaginal discharge 1 month after LPF (polypropylene mesh and glue had been used). Wall mesh exposure and purulent discharge were noted. She received antibiotics and underwent mesh ablation surgery; debris of the glue was easily identified. Patient B, a 65-year-old lady with previous hysterectomy consulted for a bulging feeling in her vagina (classification: cystocele +2; rectocele +3 stage). An LPF was performed using polypropylene soft nonabsorbable mesh and glue. One month later, an apical defect of vaginal epithelialization was detected; she received long estrogenic local treatment but had to undergo surgery when presenting malodorous discharge and mesh exposure. The exposed mesh was removed, and pieces of glue were identified, having avoided mesh attachment. Patient C had a previous abdominal hysterectomy and promontofixation using a polyester mesh with glue. She consulted to us for vaginal mesh erosion covered with purulent discharge 3.5 years after LPF in another center. At the surgery, 1 cm of the prosthesis was identified in the vagina, dissected, and sutured. One year later, she consulted for dyspareunia and purulent discharge; vaginal rigid mesh exposure with an epithelization defect and inflammatory signs was seen. During laparoscopy, prosthetic exposition and glue debris on the prosthesis were identified. In all 3 cases, debris of glue were identified in the no integrated mesh area. The suggested reasons of exposure can be the excessive amount of surgical glue applied. Moreover, a large amount of glue may be impairing tissue ingrowth through the mesh pores, causing low fibrosis and poor tissue integration [3]. Glue seems to prevent fibrosis from occurring. Its use in pelvic organ prolapse laparoscopic mesh fixation should be done with caution. No prospective studies reporting long-term comorbidities and results have been published. Copyright © 2017 American Association of Gynecologic Laparoscopists. Published by Elsevier Inc. All rights reserved.

Trends in management of pelvic organ prolapse among female Medicare beneficiaries.

PubMed

Khan, Aqsa A; Eilber, Karyn S; Clemens, J Quentin; Wu, Ning; Pashos, Chris L; Anger, Jennifer T

2015-04-01

In the last decade, many new surgical treatments have been developed to achieve less-invasive approaches to prolapse management. However, limited data exist on how the patterns of care for women with pelvic organ prolapse (POP) may have changed over the last decade, and whether mesh implantation techniques have influenced the type of specific compartment repair performed. We used a national data set to analyze the temporal trends in patterns of care for women with POP. Data were obtained from Public Use Files from the Centers for Medicare and Medicaid Services for a 5% random sample of national beneficiaries with an International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis of POP from 1999 through 2009. Current Procedural Terminology, 4th Edition and International Classification of Diseases, Ninth Revision, Clinical Modification procedure codes were used to evaluate nonsurgical and surgical management trends for this cohort. Types of surgery were categorized by prolapse compartment and combinations of repairs. After 2005, when applicable codes became available, mesh or graft repairs were also analyzed. Over the study time period, the number of women with a diagnosis of POP in any 1 year in our 5% sample of Medicare beneficiaries remained relatively stable (range, 21,245-23,268 per year). Rates of pessary insertion were also consistent at 11-13% over the study period. Of the women with a prolapse diagnosis, 14-15% underwent surgical repair, and there was little change over time in surgical management patterns based on compartment. Most commonly, multiple compartments were repaired simultaneously. There was a rapid increase in mesh use such that in 2009, 41% of all women who underwent surgery (5.8% of the total cohort) had mesh or graft inserted in their repair. Hysterectomy rates for prolapse decreased over time. Rates of vault suspension at the time of hysterectomy for prolapse were low; however, they showed a relative increase over time (22% in 1999 to 26% in 2009). Patterns and rates of prolapse repairs remained relatively unchanged from 1999 through 2009, with an exception of a rapid rise in mesh use. These data suggest that the majority of mesh techniques were used for augmentation purposes only, but did not result in an increase in apical repairs performed in the United States. There remains a disappointingly low rate of vault suspension repairs concomitantly at time of hysterectomy for POP. Copyright © 2015. Published by Elsevier Inc.

Trends in management of pelvic organ prolapse among female Medicare beneficiaries

PubMed Central

Khan, Aqsa A.; Eilber, Karyn S.; Clemens, J. Quentin; Wu, Ning; Pashos, Chris L.; Anger, Jennifer T.

2016-01-01

OBJECTIVE In the last decade, many new surgical treatments have been developed to achieve less-invasive approaches to prolapse management. However, limited data exist on how the patterns of care for women with pelvic organ prolapse (POP) may have changed over the last decade, and whether mesh implantation techniques have influenced the type of specific compartment repair performed. We used a national data set to analyze the temporal trends in patterns of care for women with POP. STUDY DESIGN Data were obtained from Public Use Files from the Centers for Medicare and Medicaid Services for a 5% random sample of national beneficiaries with an International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis of POP from 1999 through 2009. Current Procedural Terminology, 4th Edition and International Classification of Diseases, Ninth Revision, Clinical Modification procedure codes were used to evaluate nonsurgical and surgical management trends for this cohort. Types of surgery were categorized by prolapse compartment and combinations of repairs. After 2005, when applicable codes became available, mesh or graft repairs were also analyzed. RESULTS Over the study time period, the number of women with a diagnosis of POP in any 1 year in our 5% sample of Medicare beneficiaries remained relatively stable (range, 21,245–23,268 per year). Rates of pessary insertion were also consistent at 11–13% over the study period. Of the women with a prolapse diagnosis, 14–15% underwent surgical repair, and there was little change over time in surgical management patterns based on compartment. Most commonly, multiple compartments were repaired simultaneously. There was a rapid increase in mesh use such that in 2009, 41% of all women who underwent surgery (5.8% of the total cohort) had mesh or graft inserted in their repair. Hysterectomy rates for prolapse decreased over time. Rates of vault suspension at the time of hysterectomy for prolapse were low; however, they showed a relative increase over time (22% in 1999 to 26% in 2009). CONCLUSION Patterns and rates of prolapse repairs remained relatively unchanged from 1999 through 2009, with an exception of a rapid rise in mesh use. These data suggest that the majority of mesh techniques were used for augmentation purposes only, but did not result in an increase in apical repairs performed in the United States. There remains a disappointingly low rate of vault suspension repairs concomitantly at time of hysterectomy for POP. PMID:25446663

A recent advance in the automatic indexing of the biomedical literature.

PubMed

Névéol, Aurélie; Shooshan, Sonya E; Humphrey, Susanne M; Mork, James G; Aronson, Alan R

2009-10-01

The volume of biomedical literature has experienced explosive growth in recent years. This is reflected in the corresponding increase in the size of MEDLINE, the largest bibliographic database of biomedical citations. Indexers at the US National Library of Medicine (NLM) need efficient tools to help them accommodate the ensuing workload. After reviewing issues in the automatic assignment of Medical Subject Headings (MeSH terms) to biomedical text, we focus more specifically on the new subheading attachment feature for NLM's Medical Text Indexer (MTI). Natural Language Processing, statistical, and machine learning methods of producing automatic MeSH main heading/subheading pair recommendations were assessed independently and combined. The best combination achieves 48% precision and 30% recall. After validation by NLM indexers, a suitable combination of the methods presented in this paper was integrated into MTI as a subheading attachment feature producing MeSH indexing recommendations compliant with current state-of-the-art indexing practice.

Sentiment classification technology based on Markov logic networks

NASA Astrophysics Data System (ADS)

He, Hui; Li, Zhigang; Yao, Chongchong; Zhang, Weizhe

2016-07-01

With diverse online media emerging, there is a growing concern of sentiment classification problem. At present, text sentiment classification mainly utilizes supervised machine learning methods, which feature certain domain dependency. On the basis of Markov logic networks (MLNs), this study proposed a cross-domain multi-task text sentiment classification method rooted in transfer learning. Through many-to-one knowledge transfer, labeled text sentiment classification, knowledge was successfully transferred into other domains, and the precision of the sentiment classification analysis in the text tendency domain was improved. The experimental results revealed the following: (1) the model based on a MLN demonstrated higher precision than the single individual learning plan model. (2) Multi-task transfer learning based on Markov logical networks could acquire more knowledge than self-domain learning. The cross-domain text sentiment classification model could significantly improve the precision and efficiency of text sentiment classification.

Using Public Network Infrastructures for UAV Remote Sensing in Civilian Security Operations

DTIC Science & Technology

2011-03-01

leveraging public wireless communication networks for UAV-based sensor networks with respect to existing constraints and user requirements...Detection with an Autonomous Micro UAV Mesh Network . In the near future police departments, fire brigades and other homeland security ...UAV-based sensor networks with respect to existing constraints and user requirements. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION

Visualization of semantic indexing similarity over MeSH.

PubMed

Du, Haixia; Yoo, Terry S

2007-10-11

We present an interactive visualization system for the evaluation of indexing results of the MEDLINE data-base over the Medical Subject Headings (MeSH) structure in a graphical radial-tree layout. It displays indexing similarity measurements with 2D color coding and a 3D height field permitting the evaluation of the automatic Medical Text Indexer (MTI), compared with human indexers.

Design of Raft Foundations for High-Rise Buildings on Jointed Rock

NASA Astrophysics Data System (ADS)

Justo, J. L.; García-Núñez, J.-C.; Vázquez-Boza, M.; Justo, E.; Durand, P.; Azañón, J. M.

2014-07-01

This paper presents calculations of displacements and bending moments in a 2-m-thick reinforced-concrete foundation slab using three-dimensional finite-element software. A preliminary paper was presented by Justo et al. (Rock Mech Rock Eng 43:287-304, 2010). The slab is the base of a tower of 137 m height above foundation, supported on jointed and partly weathered basalt and scoria. Installation of rod extensometers at different depths below foundation allowed comparison between measured displacements and displacements calculated using moduli obtained from rock classification systems and three material models: elastic, Mohr-Coulomb and hardening (H). Although all three material models can provide acceptable results, the H model is preferable when there are unloading processes. Acceptable values of settlement may be achieved with medium meshing and an approximate distribution of loads. The absolute values of negative bending moments (tensions below) increase as the rock mass modulus decreases or when the mesh is refined. The paper stresses the importance of adequately representing the details of the distribution of loads and the necessity for fine meshing to obtain acceptable values of bending moments.

Laparoscopic Sacral Colpopexy: The "6-Points" Technique.

PubMed

Schaub, Marie; Lecointre, Lise; Faller, Emilie; Boisramé, Thomas; Baldauf, Jean-Jacques; Wattiez, Arnaud; Akladios, Cherif Youssef

To illustrate laparoscopic sacral colpopexy for pelvic organ prolapse, a new method using a simplified mesh fixation technique, with only 6 fixing points. Step-by-step explanation of the surgery using video (educative video). The video was approved by the local institutional review board. University Hospital of Strasbourg, France (Canadian Task Force Classification III). Women with multicompartment prolapse. We first dissected the promontorium and vertically incise the posterior parietal peritoneum on the right pelvic sidewall up the pouch of Douglas. We then dissect the rectovaginal septum up to the anal cap, laterally exposing the puborectalis muscle on each side. Middle rectal vessels can be coagulated and cut without increasing the risk of digestive disorders (especially constipation), but it is preferable to conserve them if the space is sufficient for suture. Then, we dissect the vesicovaginal space and realized the subtotal hysterectomy. Finally, we realized the fastening of the anterior and posterior meshes. The particularity is that we performed only 6 points for fixing the meshes: 1 on the puborectalis muscle on each side without tension (to reduce the risk of mesh contracture, dyspareunia, and chronic pelvic pain), 1 for the fixing of the anterior mesh on the anterior vaginal wall at the level of the bladder neck, and 1 on each side of the cervix for the reconstitution of the pericervical ring gathering together the anterior mesh, the pubocervical fascia, and the insertion of the uterosacral ligament at the level of the cervix and the posterior mesh. The sixth stitch fastened 1 of 2 meshes to the anterior paravertebral ligament at the level of the sacral promontory. We finished with the peritonization. The duration of surgery lasts approximately 120 minutes in well-experienced hands. Based on our experience the 6-point technique was relatively simple (few laparoscopic stiches) with few operative difficulties and was also associated with a low rate of reintervention. Surgical management of middle compartment prolapse could be performed quickly and efficiently under laparoscopy with the "6-points" technique. Copyright © 2017 AAGL. Published by Elsevier Inc. All rights reserved.

A bottom-up approach to MEDLINE indexing recommendations.

PubMed

Jimeno-Yepes, Antonio; Wilkowski, Bartłomiej; Mork, James G; Van Lenten, Elizabeth; Fushman, Dina Demner; Aronson, Alan R

2011-01-01

MEDLINE indexing performed by the US National Library of Medicine staff describes the essence of a biomedical publication in about 14 Medical Subject Headings (MeSH). Since 2002, this task is assisted by the Medical Text Indexer (MTI) program. We present a bottom-up approach to MEDLINE indexing in which the abstract is searched for indicators for a specific MeSH recommendation in a two-step process. Supervised machine learning combined with triage rules improves sensitivity of recommendations while keeping the number of recommended terms relatively small. Improvement in recommendations observed in this work warrants further exploration of this approach to MTI recommendations on a larger set of MeSH headings.

Text Classification for Organizational Researchers

PubMed Central

Kobayashi, Vladimer B.; Mol, Stefan T.; Berkers, Hannah A.; Kismihók, Gábor; Den Hartog, Deanne N.

2017-01-01

Organizations are increasingly interested in classifying texts or parts thereof into categories, as this enables more effective use of their information. Manual procedures for text classification work well for up to a few hundred documents. However, when the number of documents is larger, manual procedures become laborious, time-consuming, and potentially unreliable. Techniques from text mining facilitate the automatic assignment of text strings to categories, making classification expedient, fast, and reliable, which creates potential for its application in organizational research. The purpose of this article is to familiarize organizational researchers with text mining techniques from machine learning and statistics. We describe the text classification process in several roughly sequential steps, namely training data preparation, preprocessing, transformation, application of classification techniques, and validation, and provide concrete recommendations at each step. To help researchers develop their own text classifiers, the R code associated with each step is presented in a tutorial. The tutorial draws from our own work on job vacancy mining. We end the article by discussing how researchers can validate a text classification model and the associated output. PMID:29881249

[Development of better tolerated prosthetic materials: applications in gynecological surgery].

PubMed

Debodinance, P; Delporte, P; Engrand, J B; Boulogne, M

2002-10-01

Meshes have come to be widely used for surgical repair of the dysfunctional pelvic floor. The problem to date has been mesh intolerance. History. The first meshes were made with silver filigrees or stainless steel. Non-metallic and non-absorbable synthetic prostheses include nylon, silastic, polytetrafluoroethylene as well as expansive polyester and polypropylene forms. Most of the absorbable prostheses are made of polyglycolic acid and polyglactine 910. Classification. Four groups of biomaterials can be described according to pore size. Mechanical and biological properties. The mechanical properties of meshes have been tested industrially for resistance, pliability, elasticity and ductile qualities. These properties depend on type of tissue structure (woven or knitted) and the type of fiber used (mono and multi-filaments). The goal is to obtain a "silent" material, i.e. a material which does not trigger a host tissue reaction. Introducing the foreign body induces a "scarring" response. This fibroblastic reaction replaces the inflammatory reaction, leading to progressive colonization of the prosthesis. The major risk is infection caused by a disturbance of the inflammatory phase and bacterial development. Bacteria can be trapped in fibrotic tissue, with the risk of delayed infection. Immunological reactions may have an additive effect. These problems are not encountered with absorbable meshes. An ideal implant material must: not undergo physical modification by tissue fluids, be chemically inert, not trigger inflammatory or foreign body cell response in body tissues, be noncarcinogenic and nonallergenic, be capable of resisting mechanical stress and sterilization, and be able to be manufactured in the necessary shape. Polyester, polypropylene and expansive polytetrafluoroethylene fulfill these criteria. The ideal mesh. Eleven criteria are proposed. Complications for hernia repair. Infection and seroma are the most frequent complications with micro-porous meshes. Macro-porous meshes can cause erosive phenomena and adhesions. Retraction of synthetic tissues is observed in 20 to 30% of cases. Meshes in gynecology. In gynecology surgery, meshes made their first appearance in trans-abdominal sacrocolpopexy and slings. A detailed review of complications found in 32 articles studying slings and 22 studying sacrocolpopexy with approximately 10 types of meshes shows that intolerance of slings has oscillated between 1% with Prolene and 31% with Gore-Tex; for abdominal sacrocolpopexy the rate was between 1.7% with Prolene and 20% with Teflon. Rejection phenomena appear during the first year and are proportional to the surface area of the synthetic tissue and the proximity of the vaginal scar. New materials have been proposed over the last ten years for prolapse surgery, notably for cystocele, which accounts for 70% of all repair procedures. Nearly fifteen studies have reported a level of intolerance reaching 6%, the large majority of the meshes used being Prolene meshes. Our personal experience with 87 repair procedures has led us to the conclusion that Prolene is the most adapted mesh, allowing free tension between the bladder and the anterior vaginal wall. Continuous evaluation is needed to study these replacement materials which should in theory, improve the rate of recurrence, which is at present 20% with classic procedures not using a mesh.

Extraction of Pharmacokinetic Evidence of Drug–Drug Interactions from the Literature

PubMed Central

Kolchinsky, Artemy; Lourenço, Anália; Wu, Heng-Yi; Li, Lang; Rocha, Luis M.

2015-01-01

Drug-drug interaction (DDI) is a major cause of morbidity and mortality and a subject of intense scientific interest. Biomedical literature mining can aid DDI research by extracting evidence for large numbers of potential interactions from published literature and clinical databases. Though DDI is investigated in domains ranging in scale from intracellular biochemistry to human populations, literature mining has not been used to extract specific types of experimental evidence, which are reported differently for distinct experimental goals. We focus on pharmacokinetic evidence for DDI, essential for identifying causal mechanisms of putative interactions and as input for further pharmacological and pharmacoepidemiology investigations. We used manually curated corpora of PubMed abstracts and annotated sentences to evaluate the efficacy of literature mining on two tasks: first, identifying PubMed abstracts containing pharmacokinetic evidence of DDIs; second, extracting sentences containing such evidence from abstracts. We implemented a text mining pipeline and evaluated it using several linear classifiers and a variety of feature transforms. The most important textual features in the abstract and sentence classification tasks were analyzed. We also investigated the performance benefits of using features derived from PubMed metadata fields, various publicly available named entity recognizers, and pharmacokinetic dictionaries. Several classifiers performed very well in distinguishing relevant and irrelevant abstracts (reaching F1≈0.93, MCC≈0.74, iAUC≈0.99) and sentences (F1≈0.76, MCC≈0.65, iAUC≈0.83). We found that word bigram features were important for achieving optimal classifier performance and that features derived from Medical Subject Headings (MeSH) terms significantly improved abstract classification. We also found that some drug-related named entity recognition tools and dictionaries led to slight but significant improvements, especially in classification of evidence sentences. Based on our thorough analysis of classifiers and feature transforms and the high classification performance achieved, we demonstrate that literature mining can aid DDI discovery by supporting automatic extraction of specific types of experimental evidence. PMID:25961290

Bioacoustic Signal Classification in Cat Auditory Cortex

DTIC Science & Technology

1991-06-14

Studies Preparations for the setup to record from awake animals in a behavioral setting were initiated with the help of Dr. William Jenkins, our...temporal muscle over the right hemisphere was then retracted and the lateral cortex exposed by a craniotomy . The dura overlaying the middle ectosylvian...sites. For recording topographically identified single neurons, a wire mesh was placed over the craniotomy and the space between the grid and cortex was

Drug related webpages classification using images and text information based on multi-kernel learning

NASA Astrophysics Data System (ADS)

Hu, Ruiguang; Xiao, Liping; Zheng, Wenjuan

2015-12-01

In this paper, multi-kernel learning(MKL) is used for drug-related webpages classification. First, body text and image-label text are extracted through HTML parsing, and valid images are chosen by the FOCARSS algorithm. Second, text based BOW model is used to generate text representation, and image-based BOW model is used to generate images representation. Last, text and images representation are fused with a few methods. Experimental results demonstrate that the classification accuracy of MKL is higher than those of all other fusion methods in decision level and feature level, and much higher than the accuracy of single-modal classification.

77 FR 60475 - Draft of SWGDOC Standard Classification of Typewritten Text

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-03

... DEPARTMENT OF JUSTICE Office of Justice Programs [OJP (NIJ) Docket No. 1607] Draft of SWGDOC Standard Classification of Typewritten Text AGENCY: National Institute of Justice, DOJ. ACTION: Notice and..., ``SWGDOC Standard Classification of Typewritten Text''. The opportunity to provide comments on this...

Prospective, Randomized Study on the Use of a Prosthetic Mesh for Prevention of Parastomal Hernia of Permanent Colostomy.

PubMed

Vierimaa, Mika; Klintrup, Kai; Biancari, Fausto; Victorzon, Mikael; Carpelan-Holmström, Monika; Kössi, Jyrki; Kellokumpu, Ilmo; Rauvala, Erkki; Ohtonen, Pasi; Mäkelä, Jyrki; Rautio, Tero

2015-10-01

Prophylactic placement of a mesh has been suggested to prevent parastomal hernia, but evidence to support this approach is scarce. The aim of this study was to evaluate whether laparoscopic placement of a prophylactic, dual-component, intraperitoneal onlay mesh around a colostomy is safe and prevents parastomal hernia formation after laparoscopic abdominoperineal resection. This is a prospective, multicenter, randomized controlled clinical trial. This study was conducted at 2 university and 3 central Finnish hospitals. From 2010 to 2013, 83 patients undergoing laparoscopic abdominoperineal resection for rectal cancer were recruited. After withdrawals and exclusions, the outcome of 70 patients, 35 patients in each study group, could be examined. In the intervention group, an end colostomy was created with placement of a intraperitoneal, dual-component onlay mesh and compared with a group with a traditional stoma. The main outcome measures were the incidence of clinically and radiologically detected parastomal hernias and their extent 12 months after surgery. Stoma-related morbidity and the need for surgical repair of parastomal hernia were secondary outcome measures. Parastomal hernia was observed by clinical inspection in 5 intervention patients (14.3%) and in 12 control patients (32.3%; p = 0.049). Surgical repair of parastomal hernia was performed in 1 control patient (3.2%) and in none of the patients in the intervention group. CT detected parastomal hernia in 18 intervention patients (51.4%) and in 17 control patients (53.1%; p = 1.00). The extent of hernias was similar according to European Hernia Society classification (p = 0.41). Colostomy-related morbidity (32.3% vs 14.3%; p = 0.140) did not differ between the study groups. The study was limited by its small size and short follow-up time. Prophylactic laparoscopic placement of intraperitoneal onlay mesh does not significantly reduce the overall risk of radiologically detected parastomal hernia after laparoscopic abdominoperineal resection. However, prophylactic mesh repair was associated with significantly lower risk of clinically detected parastomal hernia.

Biaxial Mechanical Evaluation of Absorbable and Nonabsorbable Synthetic Surgical Meshes Used for Hernia Repair: Physiological Loads Modify Anisotropy Response.

PubMed

Cordero, A; Hernández-Gascón, B; Pascual, G; Bellón, J M; Calvo, B; Peña, E

2016-07-01

The aim of this study was to obtain information about the mechanical properties of six meshes commonly used for hernia repair (Surgipro(®), Optilene(®), Infinit(®), DynaMesh(®), Ultrapro™ and TIGR(®)) by planar biaxial tests. Stress-stretch behavior and equibiaxial stiffness were evaluated, and the anisotropy was determined by testing. In particular, equibiaxial test (equal simultaneous loading in both directions) and biaxial test (half of the load in one direction following the Laplace law) were selected as a representation of physiologically relevant loads. The majority of the meshes displayed values in the range of 8 and 18 (N/mm) in each direction for equibiaxial stiffness (tangent modulus under equibiaxial load state in both directions), while a few achieved 28 and 50 (N/mm) (Infinit (®) and TIGR (®)). Only the Surgipro (®) mesh exhibited planar isotropy, with similar mechanical properties regardless of the direction of loading, and an anisotropy ratio of 1.18. Optilene (®), DynaMesh (®), Ultrapro (®) and TIGR (®) exhibited moderate anisotropy with ratios of 1.82, 1.84, 2.17 and 1.47, respectively. The Infinit (®) scaffold exhibited very high anisotropy with a ratio of 3.37. These trends in material anisotropic response changed during the physiological state in the human abdominal wall, i.e. T:0.5T test, which the meshes were loaded in one direction with half the load used in the other direction. The Surgipro (®) mesh increased its anisotropic response (Anis[Formula: see text] = 0.478) and the materials that demonstrated moderate and high anisotropic responses during multiaxial testing presented a quasi-isotropic response, especially the Infinit(®) mesh that decreased its anisotropic response from 3.369 to 1.292.

[Vaginal mesh operations in the urogynecological practice after the FDA warnings. Use or not to use mesh?

PubMed

Fekete, Zoltán; Körösi, Szilvia; Németh, Gábor

2018-03-01

The prevalence of pelvic organ prolapse (POP) with aging is escalating alarmingly, and now becoming a growing epidemic among the elderly. Synthetic transvaginal mesh (TVM) has been employed with increasing popularity in the treatment of POP until the end of the last decade. After the U.S. Drug and Food Administration (FDA) warnings in the years 2008 and 2011, the number of vaginal mesh operations has decreased dramatically. The aim of the study was to evaluate and compare the anti-POP effectivity, the anti-stress incontinence (anti-SUI) efficacy, and the late (36 months) post-operative complications of the anterior vaginoplasty and the TVM operations. We analysed the clinical data from 120 patients with stage II-III anterior prolapse and concomitant SUI who had undergone surgery at a tertiary referral centre in Hungary between January 2013 and January 2014. Sixty patients underwent Kelly-Stoeckel vaginoplasty and the other 60 cases had TVM operation. The surgical complications were classified using the Clavien-Dindo (CD) classification system. The anti-POP (91.6% vs. 63.3%; p<0.001) and the anti-SUI efficacy (90% vs. 55%, p<0.001) were significantly higher in the TVM group than in the vaginoplasty group, while the overall extrusion rate was found 8.3% after a 3-year follow-up. The Clavien-Dindo score (CD) proved that the early post-operative complication profile was similar among the TVM patients as compared to the vaginoplasty group (p = 0.405). Vaginal mesh surgery represents an effective procedure for prolapse and concomitant SUI with a decreased risk of short- and long-term complications. Orv Hetil. 2018; 159(10): 397-404.

Outcomes and complications of trans-vaginal mesh repair using the Prolift™ kit for pelvic organ prolapse at 4 years median follow-up in a tertiary referral centre.

PubMed

Khan, Zainab A; Thomas, Lee; Emery, Simon J

2014-12-01

To evaluate the anatomical, functional and post-operative outcomes of polypropylene mesh (Prolift™) in the surgical management of pelvic organ prolapse (POP). A single-centre observational study of 106 successive patients, who underwent Prolift™ mesh repair (POP ≥ 2) with a median follow-up of 4 years, was performed. Outcomes of interest measured included patient demographics, intra and post-operative complications, concomitant procedures for POP or urinary incontinence. Using the Baden-Walker classification, grade ≥2 prolapses in the operated compartment were deemed as surgical failure. Validated questionnaires including ICIQ-VS and ICIQ-UI were used to assess functional outcome. Of the 106 patients, 56 had an anterior, 36 a posterior and 14 a total Prolift™. 101 patients were available for follow-up (median 4 years). 82 women underwent a clinical follow-up whilst 19 underwent a telephonic follow-up. Peri-operative bladder injury was noted in 2 (1.9 %) cases. Six (5.6 %) patients developed mesh exposure post-operatively. Re-operation rates for recurrent prolapse in the operated compartment were 2.8 % (n = 3). At follow-up, prolapse recurrence in the operated compartment was noted in another 7.3 % (n = 6) patients. Combining re-operations for POP and recurrences noted during follow-up, the revised failure rate was 10.1 % (n = 9). De novo prolapse in the non-operated compartment occurred in 19.5 % (n = 16) women. Our study demonstrates that Prolift™ vaginal mesh surgery offers anatomical cure rates of 89.9 %. A higher rate of de novo recurrence in the non-operated compartment was noted suggesting that surgical correction in one compartment may exacerbate recurrence in other compartments.

A Matlab-based finite-difference solver for the Poisson problem with mixed Dirichlet-Neumann boundary conditions

NASA Astrophysics Data System (ADS)

Reimer, Ashton S.; Cheviakov, Alexei F.

2013-03-01

A Matlab-based finite-difference numerical solver for the Poisson equation for a rectangle and a disk in two dimensions, and a spherical domain in three dimensions, is presented. The solver is optimized for handling an arbitrary combination of Dirichlet and Neumann boundary conditions, and allows for full user control of mesh refinement. The solver routines utilize effective and parallelized sparse vector and matrix operations. Computations exhibit high speeds, numerical stability with respect to mesh size and mesh refinement, and acceptable error values even on desktop computers. Catalogue identifier: AENQ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENQ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License v3.0 No. of lines in distributed program, including test data, etc.: 102793 No. of bytes in distributed program, including test data, etc.: 369378 Distribution format: tar.gz Programming language: Matlab 2010a. Computer: PC, Macintosh. Operating system: Windows, OSX, Linux. RAM: 8 GB (8, 589, 934, 592 bytes) Classification: 4.3. Nature of problem: To solve the Poisson problem in a standard domain with “patchy surface”-type (strongly heterogeneous) Neumann/Dirichlet boundary conditions. Solution method: Finite difference with mesh refinement. Restrictions: Spherical domain in 3D; rectangular domain or a disk in 2D. Unusual features: Choice between mldivide/iterative solver for the solution of large system of linear algebraic equations that arise. Full user control of Neumann/Dirichlet boundary conditions and mesh refinement. Running time: Depending on the number of points taken and the geometry of the domain, the routine may take from less than a second to several hours to execute.

Motif-Based Text Mining of Microbial Metagenome Redundancy Profiling Data for Disease Classification.

PubMed

Wang, Yin; Li, Rudong; Zhou, Yuhua; Ling, Zongxin; Guo, Xiaokui; Xie, Lu; Liu, Lei

2016-01-01

Text data of 16S rRNA are informative for classifications of microbiota-associated diseases. However, the raw text data need to be systematically processed so that features for classification can be defined/extracted; moreover, the high-dimension feature spaces generated by the text data also pose an additional difficulty. Here we present a Phylogenetic Tree-Based Motif Finding algorithm (PMF) to analyze 16S rRNA text data. By integrating phylogenetic rules and other statistical indexes for classification, we can effectively reduce the dimension of the large feature spaces generated by the text datasets. Using the retrieved motifs in combination with common classification methods, we can discriminate different samples of both pneumonia and dental caries better than other existing methods. We extend the phylogenetic approaches to perform supervised learning on microbiota text data to discriminate the pathological states for pneumonia and dental caries. The results have shown that PMF may enhance the efficiency and reliability in analyzing high-dimension text data.

Practical use of medical terminology in curriculum mapping.

PubMed

Komenda, Martin; Schwarz, Daniel; Švancara, Jan; Vaitsis, Christos; Zary, Nabil; Dušek, Ladislav

2015-08-01

Various information systems for medical curriculum mapping and harmonization have been developed and successfully applied to date. However, the methods for exploiting the datasets captured inside the systems are rather lacking. We reviewed the existing medical terminologies, nomenclatures, coding and classification systems in order to select the most suitable one and apply it in delivering visual analytic tools and reports for the benefit of medical curriculum designers and innovators. A formal description of a particular curriculum of general medicine is based on 1347 learning units covering 7075 learning outcomes. Two data-analytical reports have been developed and discussed, showing how the curriculum is consistent with the MeSH thesaurus and how the MeSH thesaurus can be used to demonstrate interconnectivity of the curriculum through association analysis. Although the MeSH thesaurus is designed mainly to index medical literature and support searching through bibliographic databases, we have proved its use in medical curriculum mapping as being beneficial for curriculum designers and innovators. The presented approach can be followed wherever needed to identify all the mandatory components used for transparent and comprehensive overview of medical curriculum data. Copyright © 2015 Elsevier Ltd. All rights reserved.

Topological Patterns for Scalable Representation and Analysis of Dataflow Graphs

DTIC Science & Technology

2011-11-01

dimensional mesh structure. Such a structure is of particular use to model DSP architectures in which data flows across a network of processing elements...ACSSC.1998.751616 3. Andrews, J.G., Ghosh, A., Muhamed, R.: Fundamentals of WiMAX: understanding broad- band wireless networking . Prentice Hall (2007... SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report (SAR) 18. NUMBER OF PAGES 23 19a. NAME OF RESPONSIBLE PERSON a. REPORT

Construction and temporal behaviour study of multi RLC intense light pulses for dermatological applications.

PubMed

Hamoudi, Walid K; Ismail, Raid A; Shakir, Hussein A

2017-10-01

Driving a flash lamp in an intense pulsed light system requires a high-voltage DC power supply, capacitive energy storage and a flash lamp triggering unit. Single, double, triple and quadruple-mesh discharge and triggering circuits were constructed to provide intense light pulses of variable energy and time durations. The system was treated as [Formula: see text] circuit in some cases and [Formula: see text] circuit in others with a light pulse profile following the temporal behaviour of the exciting current pulse. Distributing the energy delivered to one lamp onto a number of LC meshes permitted longer current pulses, and consequently increased the light pulse length. Positive results were obtained when using the system to treat skin wrinkles.

Proximal Femoral Reconstructions with Bone Impaction Grafting and Metal Mesh

PubMed Central

Comba, Fernando; Piccaluga, Francisco

2009-01-01

Extensive circumferential proximal cortical bone loss is considered by some a contraindication for impaction bone grafting in the femur. We asked whether reconstruction with a circumferential metal mesh, impacted bone allografts, and a cemented stem would lead to acceptable survival in these patients. We retrospectively reviewed 14 patients (15 hips) with severe proximal femoral bone defects (average, 12 cm long; 14 type IV and one type IIIB using the classification of Della Valle and Paprosky) reconstructed with this method. The minimum followup was 20 months (average, 43.2 months; range, 20–72 months). Preoperative Merle D’Aubigné and Postel score averaged 4.8 points. With revision of the stem as the end point, the survivorship of the implant was 100% at one year and 86.6% at 72 months. The mean functional score at last followup was 14.4 points. We observed two fractures of the metal mesh at 31 and 48 months in cases reconstructed with a stem that did not bypass the mesh. Dislocation (3 cases) and acute deep infection (3 cases) were the most frequent complications. Patients with complete absence of the proximal femur may be candidates for biological proximal femoral reconstructions using this salvage procedure. Bone impaction grafting must be a routine technique if this method is selected. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:19294476

[EFFECTIVENESS OF PREPERITONEAL HERNIORRHAPHY WITH Ultrapro Plug MESH FOR UMBILICAL HERNIA REPAIR IN ADULTS].

PubMed

Xie, Yanyan; Ma, Dongyang; Song, Yinghan; Lu, Anqing; Wang, Menghong; Lei, Wenzhang

2016-06-08

To explore the effectiveness of preperitoneal herniorrhaphy with Ultrapro Plug (UPP) mesh for umbilical hernia repair in adults. Between September 2011 and June 2015, 71 patients with umbilical hernia underwent preperitoneal herniorrhaphy with UPP mesh. There were 26 males and 45 females, aged 19-92 years (mean, 54.3 years). The disease duration was 45 days to 30 years (median, 18 months). Umbilical hernia was diagnosed through physical examination, ultrasound, and other relevant auxiliary examination. According to American Society of Anesthesiologists (ASA) classification, 12 cases were rated as grade Ⅰ, 34 cases as grade Ⅱ, 21 cases as grade Ⅲ, and 4?cases as grade Ⅳ. The operation time, postoperative hospitalization time, complication, and recurrence were recorded. The diameter of hernia ring ranged 0.5-3.0 cm (mean, 1.8 cm). There was no vessel or intestine injury. The operation time was 12-35 minutes (mean, 22.4 minutes); postoperative hospitalization time was 12-48 hours (mean, 16.3 hours). Fat liquefaction of incision occurred in 2 cases, and primary healing of incision was obtained in the other cases. Sixty-nine patients were followed up 8-51 months (median, 28 months). Hernia recurrence and patch infection occurred in 1 case respectively during follow-up. No postoperative foreign body sensation and chronic pain occurred. Repairing umbilical hernia in adults with UPP mesh should be safe and reliable, because it has the advantages of short operation time, short hospital stay, less complication, and lower incidence of recurrence.

Semantic similarity measures in the biomedical domain by leveraging a web search engine.

PubMed

Hsieh, Sheau-Ling; Chang, Wen-Yung; Chen, Chi-Huang; Weng, Yung-Ching

2013-07-01

Various researches in web related semantic similarity measures have been deployed. However, measuring semantic similarity between two terms remains a challenging task. The traditional ontology-based methodologies have a limitation that both concepts must be resided in the same ontology tree(s). Unfortunately, in practice, the assumption is not always applicable. On the other hand, if the corpus is sufficiently adequate, the corpus-based methodologies can overcome the limitation. Now, the web is a continuous and enormous growth corpus. Therefore, a method of estimating semantic similarity is proposed via exploiting the page counts of two biomedical concepts returned by Google AJAX web search engine. The features are extracted as the co-occurrence patterns of two given terms P and Q, by querying P, Q, as well as P AND Q, and the web search hit counts of the defined lexico-syntactic patterns. These similarity scores of different patterns are evaluated, by adapting support vector machines for classification, to leverage the robustness of semantic similarity measures. Experimental results validating against two datasets: dataset 1 provided by A. Hliaoutakis; dataset 2 provided by T. Pedersen, are presented and discussed. In dataset 1, the proposed approach achieves the best correlation coefficient (0.802) under SNOMED-CT. In dataset 2, the proposed method obtains the best correlation coefficient (SNOMED-CT: 0.705; MeSH: 0.723) with physician scores comparing with measures of other methods. However, the correlation coefficients (SNOMED-CT: 0.496; MeSH: 0.539) with coder scores received opposite outcomes. In conclusion, the semantic similarity findings of the proposed method are close to those of physicians' ratings. Furthermore, the study provides a cornerstone investigation for extracting fully relevant information from digitizing, free-text medical records in the National Taiwan University Hospital database.

Free-Text Disease Classification

DTIC Science & Technology

2011-09-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS FREE-TEXT DISEASE CLASSIFICATION by Craig Maxey September 2011 Thesis Advisor: Lyn R. Whitaker...2104-10-31 Free-Text Disease Classification Craig Maxey Naval Postgraduate School Monterey, CA 93943 Department of the Navy Approved for public...POSTGRADUATE SCHOOL September 2011 Author: Craig Maxey Approved by: Lyn R. Whitaker Thesis Advisor Samuel E. Buttrey Second Reader Robert F. Dell Chair

The complete digital workflow in fixed prosthodontics: a systematic review.

PubMed

Joda, Tim; Zarone, Fernando; Ferrari, Marco

2017-09-19

The continuous development in dental processing ensures new opportunities in the field of fixed prosthodontics in a complete virtual environment without any physical model situations. The aim was to compare fully digitalized workflows to conventional and/or mixed analog-digital workflows for the treatment with tooth-borne or implant-supported fixed reconstructions. A PICO strategy was executed using an electronic (MEDLINE, EMBASE, Google Scholar) plus manual search up to 2016-09-16 focusing on RCTs investigating complete digital workflows in fixed prosthodontics with regard to economics or esthetics or patient-centered outcomes with or without follow-up or survival/success rate analysis as well as complication assessment of at least 1 year under function. The search strategy was assembled from MeSH-Terms and unspecific free-text words: {(("Dental Prosthesis" [MeSH]) OR ("Crowns" [MeSH]) OR ("Dental Prosthesis, Implant-Supported" [MeSH])) OR ((crown) OR (fixed dental prosthesis) OR (fixed reconstruction) OR (dental bridge) OR (implant crown) OR (implant prosthesis) OR (implant restoration) OR (implant reconstruction))} AND {("Computer-Aided Design" [MeSH]) OR ((digital workflow) OR (digital technology) OR (computerized dentistry) OR (intraoral scan) OR (digital impression) OR (scanbody) OR (virtual design) OR (digital design) OR (cad/cam) OR (rapid prototyping) OR (monolithic) OR (full-contour))} AND {("Dental Technology" [MeSH) OR ((conventional workflow) OR (lost-wax-technique) OR (porcelain-fused-to-metal) OR (PFM) OR (implant impression) OR (hand-layering) OR (veneering) OR (framework))} AND {(("Study, Feasibility" [MeSH]) OR ("Survival" [MeSH]) OR ("Success" [MeSH]) OR ("Economics" [MeSH]) OR ("Costs, Cost Analysis" [MeSH]) OR ("Esthetics, Dental" [MeSH]) OR ("Patient Satisfaction" [MeSH])) OR ((feasibility) OR (efficiency) OR (patient-centered outcome))}. Assessment of risk of bias in selected studies was done at a 'trial level' including random sequence generation, allocation concealment, blinding, completeness of outcome data, selective reporting, and other bias using the Cochrane Collaboration tool. A judgment of risk of bias was assigned if one or more key domains had a high or unclear risk of bias. An official registration of the systematic review was not performed. The systematic search identified 67 titles, 32 abstracts thereof were screened, and subsequently, three full-texts included for data extraction. Analysed RCTs were heterogeneous without follow-up. One study demonstrated that fully digitally produced dental crowns revealed the feasibility of the process itself; however, the marginal precision was lower for lithium disilicate (LS2) restorations (113.8 μm) compared to conventional metal-ceramic (92.4 μm) and zirconium dioxide (ZrO2) crowns (68.5 μm) (p < 0.05). Another study showed that leucite-reinforced glass ceramic crowns were esthetically favoured by the patients (8/2 crowns) and clinicians (7/3 crowns) (p < 0.05). The third study investigated implant crowns. The complete digital workflow was more than twofold faster (75.3 min) in comparison to the mixed analog-digital workflow (156.6 min) (p < 0.05). No RCTs could be found investigating multi-unit fixed dental prostheses (FDP). The number of RCTs testing complete digital workflows in fixed prosthodontics is low. Scientifically proven recommendations for clinical routine cannot be given at this time. Research with high-quality trials seems to be slower than the industrial progress of available digital applications. Future research with well-designed RCTs including follow-up observation is compellingly necessary in the field of complete digital processing.

Open and Laparo-Endoscopic Repair of Incarcerated Abdominal Wall Hernias by the Use of Biological and Biosynthetic Meshes.

PubMed

Fortelny, René H; Hofmann, Anna; May, Christopher; Köckerling, Ferdinand

2016-01-01

Although recently published guidelines recommend against the use of synthetic non-absorbable materials in cases of potentially contaminated or contaminated surgical fields due to the increased risk of infection (1, 2), the use of bio-prosthetic meshes for abdominal wall or ventral hernia repair is still controversially discussed in such cases. Bio-prosthetic meshes have been recommended due to less susceptibility for infection and the decreased risk of subsequent mesh explantation. The purpose of this review is to elucidate if there are any indications for the use of biological and biosynthetic meshes in incarcerated abdominal wall hernias based on the recently published literature. A literature search of the Medline database using the PubMed search engine, using the keywords returned 486 articles up to June 2015. The full text of 486 articles was assessed and 13 relevant papers were identified including 5 retrospective case cohort studies, 2 case-controlled studies, and 6 case series. The results of Franklin et al. (3-5) included the highest number of biological mesh repairs (Surgisis(®)) by laparoscopic IPOM in infected fields, which demonstrated a very low incidence of infection and recurrence (0.7 and 5.2%). Han et al. (6) reported in his retrospective study, the highest number of treated patients due to incarcerated hernias by open approach using acellular dermal matrix (ADM(®)) with very low rate of infection as well as recurrences (1.6 and 15.9%). Both studies achieved acceptable outcome in a follow-up of at least 3.5 years compared to the use of synthetic mesh in this high-risk population (7). Currently, there is a very limited evidence for the use of biological and biosynthetic meshes in strangulated hernias in either open or laparo-endoscopic repair. Finally, there is an urgent need to start with randomized controlled comparative trials as well as to support registries with data to achieve more knowledge for tailored indication for the use of biological meshes.

Fluid intake from beverages across age groups: a systematic review.

PubMed

Özen, A E; Bibiloni, M Del Mar; Pons, A; Tur, J A

2015-10-01

Fluid intake, especially water, is essential for human life and also necessary for physical and mental function. The present study aimed to assess beverage consumption across age groups. A systematic review was conducted. Original research in English language publications and available studies (or abstracts in English) from 2000 to 2013 was searched for by using the medical subheading (MeSH) terms: ('beverage' OR 'fluid' [Major]) AND ('consumption' [Mesh] OR 'drinking' [Mesh] OR 'intake' [Mesh]) AND ('child' [Mesh] OR 'adolescent' [Mesh] OR 'adult' [Mesh]). Article selection was restricted to those papers covering healthy populations of all age groups in a nationwide sample, or from a representative sample of the population of a city or cities, which examined the trends or patterns of beverage intake and the determinants of beverage intake. Sixty-five studies were identified with respect to beverage consumption across age groups. The papers were screened by thoroughly reading titles or abstracts. Full-text articles were assessed by three investigators. Total beverage intake varied between 0.6 and 3.5 L day(-1) among all age groups (males more than females). Plain water contributed up to 58%, 75% and 80% of the total beverage intake in children, adolescents and adults, respectively. Milk consumption was higher among children; consumption of soft drinks was higher among adolescents; and the consumption of tea, coffee and alcoholic beverages was higher among adults. Plain water is the main water source for all age groups and the consumption of other beverages varies according to age. © 2014 The British Dietetic Association Ltd.

ESPEN endorsed recommendations. Definition and classification of intestinal failure in adults.

PubMed

Pironi, Loris; Arends, Jann; Baxter, Janet; Bozzetti, Federico; Peláez, Rosa Burgos; Cuerda, Cristina; Forbes, Alastair; Gabe, Simon; Gillanders, Lyn; Holst, Mette; Jeppesen, Palle Bekker; Joly, Francisca; Kelly, Darlene; Klek, Stanislaw; Irtun, Øivind; Olde Damink, S W; Panisic, Marina; Rasmussen, Henrik Højgaard; Staun, Michael; Szczepanek, Kinga; Van Gossum, André; Wanten, Geert; Schneider, Stéphane Michel; Shaffer, Jon

2015-04-01

Intestinal failure (IF) is not included in the list of PubMed Mesh terms, as failure is the term describing a state of non functioning of other organs, and as such is not well recognized. No scientific society has yet devised a formal definition and classification of IF. The European Society for Clinical Nutrition and Metabolism guideline committee endorsed its "home artificial nutrition and chronic IF" and "acute IF" special interest groups to write recommendations on these issues. After a Medline Search, in December 2013, for "intestinal failure" and "review"[Publication Type], the project was developed using the Delphi round methodology. The final consensus was reached on March 2014, after 5 Delphi rounds and two live meetings. The recommendations comprise the definition of IF, a functional and a pathophysiological classification for both acute and chronic IF and a clinical classification of chronic IF. IF was defined as "the reduction of gut function below the minimum necessary for the absorption of macronutrients and/or water and electrolytes, such that intravenous supplementation is required to maintain health and/or growth". This formal definition and classification of IF, will facilitate communication and cooperation among professionals in clinical practice, organization and management, and research. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Porous Shape Memory Polymers

PubMed Central

Hearon, Keith; Singhal, Pooja; Horn, John; Small, Ward; Olsovsky, Cory; Maitland, Kristen C.; Wilson, Thomas S.; Maitland, Duncan J.

2013-01-01

Porous shape memory polymers (SMPs) include foams, scaffolds, meshes, and other polymeric substrates that possess porous three-dimensional macrostructures. Porous SMPs exhibit active structural and volumetric transformations and have driven investigations in fields ranging from biomedical engineering to aerospace engineering to the clothing industry. The present review article examines recent developments in porous SMPs, with focus given to structural and chemical classification, methods of characterization, and applications. We conclude that the current body of literature presents porous SMPs as highly interesting smart materials with potential for industrial use. PMID:23646038

kappa-Version of Finite Element Method: A New Mathematical and Computational Framework for BVP and IVP

DTIC Science & Technology

2007-01-01

differentiability, fluid-solid interaction, error estimation, re-discretization, moving meshes 16. SECURITY CLASSIFICATION OF: 17 . LIMITATION OF 18. NUMBER...method the weight function is an indepen- dent function v = 0 6 4Ph , with v = 0 on F, if W = W0 on F1. 2. Galerkin method (GM): If Wh is an approximation...This can be demonstrated by considering a simple I-D case (like described above) in which the discretization 17 is uniform with characteristic length

Prediction of cause of death from forensic autopsy reports using text classification techniques: A comparative study.

PubMed

Mujtaba, Ghulam; Shuib, Liyana; Raj, Ram Gopal; Rajandram, Retnagowri; Shaikh, Khairunisa

2018-07-01

Automatic text classification techniques are useful for classifying plaintext medical documents. This study aims to automatically predict the cause of death from free text forensic autopsy reports by comparing various schemes for feature extraction, term weighing or feature value representation, text classification, and feature reduction. For experiments, the autopsy reports belonging to eight different causes of death were collected, preprocessed and converted into 43 master feature vectors using various schemes for feature extraction, representation, and reduction. The six different text classification techniques were applied on these 43 master feature vectors to construct a classification model that can predict the cause of death. Finally, classification model performance was evaluated using four performance measures i.e. overall accuracy, macro precision, macro-F-measure, and macro recall. From experiments, it was found that that unigram features obtained the highest performance compared to bigram, trigram, and hybrid-gram features. Furthermore, in feature representation schemes, term frequency, and term frequency with inverse document frequency obtained similar and better results when compared with binary frequency, and normalized term frequency with inverse document frequency. Furthermore, the chi-square feature reduction approach outperformed Pearson correlation, and information gain approaches. Finally, in text classification algorithms, support vector machine classifier outperforms random forest, Naive Bayes, k-nearest neighbor, decision tree, and ensemble-voted classifier. Our results and comparisons hold practical importance and serve as references for future works. Moreover, the comparison outputs will act as state-of-art techniques to compare future proposals with existing automated text classification techniques. Copyright © 2017 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Surgical outcome of mesh and suture repair in primary umbilical hernia: postoperative complications and recurrence.

PubMed

Winsnes, A; Haapamäki, M M; Gunnarsson, U; Strigård, K

2016-08-01

To compare recurrence and surgical complications following two dominating techniques: the use of suture and mesh in umbilical hernia repair. 379 consecutive umbilical hernia repair procedures performed between 1 January 2005 and 14 March 2014 in a university setting were included. Gathering was made using International Classification of Diseases codes for both procedure and diagnosis. Each patient record was scrutinized with respect to 45 variables, and the results entered in a database. Exclusion <18 years-of-age (32), non-primary umbilical hernia (25), wrong diagnosis (7), concomitant major abdominal surgery (5), double registration (3) and pregnancy (1) left 306 patients eligible for analysis. Gender distribution was 97 women and 209 men. There was no difference between mesh and suture with regard to the primary outcome variable, cumulative recurrence rate, 8.4 %. Recurrence was both self-reported and found on clinical revisit and defined as recurrence when verified by a clinician and/or radiologist. Results presented as odds ratio (OR) with 95 % confidence interval (CI) show a significantly higher risk for recurrence in patients with a coexisting hernia OR 2.84, 95 % CI 1.24-6.48. Secondary outcome, postoperative surgical complication (n = 51 occurrences), included an array of postoperative surgical events commencing within 30 days after surgery. Complication rate was significantly higher in patients receiving mesh repair OR 6.63, 95 % CI 2.29-20.38. Suture repair decreases the risk for surgical complications, especially infection without an increase in recurrence rate. The risk for recurrence is increased in patients with a history of another hernia.

The Protein-Protein Interaction tasks of BioCreative III: classification/ranking of articles and linking bio-ontology concepts to full text.

PubMed

Krallinger, Martin; Vazquez, Miguel; Leitner, Florian; Salgado, David; Chatr-Aryamontri, Andrew; Winter, Andrew; Perfetto, Livia; Briganti, Leonardo; Licata, Luana; Iannuccelli, Marta; Castagnoli, Luisa; Cesareni, Gianni; Tyers, Mike; Schneider, Gerold; Rinaldi, Fabio; Leaman, Robert; Gonzalez, Graciela; Matos, Sergio; Kim, Sun; Wilbur, W John; Rocha, Luis; Shatkay, Hagit; Tendulkar, Ashish V; Agarwal, Shashank; Liu, Feifan; Wang, Xinglong; Rak, Rafal; Noto, Keith; Elkan, Charles; Lu, Zhiyong; Dogan, Rezarta Islamaj; Fontaine, Jean-Fred; Andrade-Navarro, Miguel A; Valencia, Alfonso

2011-10-03

Determining usefulness of biomedical text mining systems requires realistic task definition and data selection criteria without artificial constraints, measuring performance aspects that go beyond traditional metrics. The BioCreative III Protein-Protein Interaction (PPI) tasks were motivated by such considerations, trying to address aspects including how the end user would oversee the generated output, for instance by providing ranked results, textual evidence for human interpretation or measuring time savings by using automated systems. Detecting articles describing complex biological events like PPIs was addressed in the Article Classification Task (ACT), where participants were asked to implement tools for detecting PPI-describing abstracts. Therefore the BCIII-ACT corpus was provided, which includes a training, development and test set of over 12,000 PPI relevant and non-relevant PubMed abstracts labeled manually by domain experts and recording also the human classification times. The Interaction Method Task (IMT) went beyond abstracts and required mining for associations between more than 3,500 full text articles and interaction detection method ontology concepts that had been applied to detect the PPIs reported in them. A total of 11 teams participated in at least one of the two PPI tasks (10 in ACT and 8 in the IMT) and a total of 62 persons were involved either as participants or in preparing data sets/evaluating these tasks. Per task, each team was allowed to submit five runs offline and another five online via the BioCreative Meta-Server. From the 52 runs submitted for the ACT, the highest Matthew's Correlation Coefficient (MCC) score measured was 0.55 at an accuracy of 89% and the best AUC iP/R was 68%. Most ACT teams explored machine learning methods, some of them also used lexical resources like MeSH terms, PSI-MI concepts or particular lists of verbs and nouns, some integrated NER approaches. For the IMT, a total of 42 runs were evaluated by comparing systems against manually generated annotations done by curators from the BioGRID and MINT databases. The highest AUC iP/R achieved by any run was 53%, the best MCC score 0.55. In case of competitive systems with an acceptable recall (above 35%) the macro-averaged precision ranged between 50% and 80%, with a maximum F-Score of 55%. The results of the ACT task of BioCreative III indicate that classification of large unbalanced article collections reflecting the real class imbalance is still challenging. Nevertheless, text-mining tools that report ranked lists of relevant articles for manual selection can potentially reduce the time needed to identify half of the relevant articles to less than 1/4 of the time when compared to unranked results. Detecting associations between full text articles and interaction detection method PSI-MI terms (IMT) is more difficult than might be anticipated. This is due to the variability of method term mentions, errors resulting from pre-processing of articles provided as PDF files, and the heterogeneity and different granularity of method term concepts encountered in the ontology. However, combining the sophisticated techniques developed by the participants with supporting evidence strings derived from the articles for human interpretation could result in practical modules for biological annotation workflows.

The Protein-Protein Interaction tasks of BioCreative III: classification/ranking of articles and linking bio-ontology concepts to full text

PubMed Central

2011-01-01

Background Determining usefulness of biomedical text mining systems requires realistic task definition and data selection criteria without artificial constraints, measuring performance aspects that go beyond traditional metrics. The BioCreative III Protein-Protein Interaction (PPI) tasks were motivated by such considerations, trying to address aspects including how the end user would oversee the generated output, for instance by providing ranked results, textual evidence for human interpretation or measuring time savings by using automated systems. Detecting articles describing complex biological events like PPIs was addressed in the Article Classification Task (ACT), where participants were asked to implement tools for detecting PPI-describing abstracts. Therefore the BCIII-ACT corpus was provided, which includes a training, development and test set of over 12,000 PPI relevant and non-relevant PubMed abstracts labeled manually by domain experts and recording also the human classification times. The Interaction Method Task (IMT) went beyond abstracts and required mining for associations between more than 3,500 full text articles and interaction detection method ontology concepts that had been applied to detect the PPIs reported in them. Results A total of 11 teams participated in at least one of the two PPI tasks (10 in ACT and 8 in the IMT) and a total of 62 persons were involved either as participants or in preparing data sets/evaluating these tasks. Per task, each team was allowed to submit five runs offline and another five online via the BioCreative Meta-Server. From the 52 runs submitted for the ACT, the highest Matthew's Correlation Coefficient (MCC) score measured was 0.55 at an accuracy of 89% and the best AUC iP/R was 68%. Most ACT teams explored machine learning methods, some of them also used lexical resources like MeSH terms, PSI-MI concepts or particular lists of verbs and nouns, some integrated NER approaches. For the IMT, a total of 42 runs were evaluated by comparing systems against manually generated annotations done by curators from the BioGRID and MINT databases. The highest AUC iP/R achieved by any run was 53%, the best MCC score 0.55. In case of competitive systems with an acceptable recall (above 35%) the macro-averaged precision ranged between 50% and 80%, with a maximum F-Score of 55%. Conclusions The results of the ACT task of BioCreative III indicate that classification of large unbalanced article collections reflecting the real class imbalance is still challenging. Nevertheless, text-mining tools that report ranked lists of relevant articles for manual selection can potentially reduce the time needed to identify half of the relevant articles to less than 1/4 of the time when compared to unranked results. Detecting associations between full text articles and interaction detection method PSI-MI terms (IMT) is more difficult than might be anticipated. This is due to the variability of method term mentions, errors resulting from pre-processing of articles provided as PDF files, and the heterogeneity and different granularity of method term concepts encountered in the ontology. However, combining the sophisticated techniques developed by the participants with supporting evidence strings derived from the articles for human interpretation could result in practical modules for biological annotation workflows. PMID:22151929

Methodology for the Evaluation of the Algorithms for Text Line Segmentation Based on Extended Binary Classification

NASA Astrophysics Data System (ADS)

Brodic, D.

2011-01-01

Text line segmentation represents the key element in the optical character recognition process. Hence, testing of text line segmentation algorithms has substantial relevance. All previously proposed testing methods deal mainly with text database as a template. They are used for testing as well as for the evaluation of the text segmentation algorithm. In this manuscript, methodology for the evaluation of the algorithm for text segmentation based on extended binary classification is proposed. It is established on the various multiline text samples linked with text segmentation. Their results are distributed according to binary classification. Final result is obtained by comparative analysis of cross linked data. At the end, its suitability for different types of scripts represents its main advantage.

A Data Augmentation Approach to Short Text Classification

ERIC Educational Resources Information Center

Rosario, Ryan Robert

2017-01-01

Text classification typically performs best with large training sets, but short texts are very common on the World Wide Web. Can we use resampling and data augmentation to construct larger texts using similar terms? Several current methods exist for working with short text that rely on using external data and contexts, or workarounds. Our focus is…

A Semi-supervised Heat Kernel Pagerank MBO Algorithm for Data Classification

DTIC Science & Technology

2016-07-01

financial predictions, etc. and is finding growing use in text mining studies. In this paper, we present an efficient algorithm for classification of high...video data, set of images, hyperspectral data, medical data, text data, etc. Moreover, the framework provides a way to analyze data whose different...also be incorporated. For text classification, one can use tfidf (term frequency inverse document frequency) to form feature vectors for each document

Towards a Holistic Cortical Thickness Descriptor: Heat Kernel-Based Grey Matter Morphology Signatures.

PubMed

Wang, Gang; Wang, Yalin

2017-02-15

In this paper, we propose a heat kernel based regional shape descriptor that may be capable of better exploiting volumetric morphological information than other available methods, thereby improving statistical power on brain magnetic resonance imaging (MRI) analysis. The mechanism of our analysis is driven by the graph spectrum and the heat kernel theory, to capture the volumetric geometry information in the constructed tetrahedral meshes. In order to capture profound brain grey matter shape changes, we first use the volumetric Laplace-Beltrami operator to determine the point pair correspondence between white-grey matter and CSF-grey matter boundary surfaces by computing the streamlines in a tetrahedral mesh. Secondly, we propose multi-scale grey matter morphology signatures to describe the transition probability by random walk between the point pairs, which reflects the inherent geometric characteristics. Thirdly, a point distribution model is applied to reduce the dimensionality of the grey matter morphology signatures and generate the internal structure features. With the sparse linear discriminant analysis, we select a concise morphology feature set with improved classification accuracies. In our experiments, the proposed work outperformed the cortical thickness features computed by FreeSurfer software in the classification of Alzheimer's disease and its prodromal stage, i.e., mild cognitive impairment, on publicly available data from the Alzheimer's Disease Neuroimaging Initiative. The multi-scale and physics based volumetric structure feature may bring stronger statistical power than some traditional methods for MRI-based grey matter morphology analysis. Copyright © 2016 Elsevier Inc. All rights reserved.

Radon exposure and tumors of the central nervous system.

PubMed

Ruano-Ravina, Alberto; Dacosta-Urbieta, Ana; Barros-Dios, Juan Miguel; Kelsey, Karl T

2017-03-15

To review the published evidence of links between radon exposure and central nervous system tumors through a systematic review of the scientific literature. We performed a thorough bibliographic search in Medline (PubMed) and EMBASE. We combined MeSH (Medical Subject Heading) terms and free text. We developed a purpose-designed scale to assess the quality of the included manuscripts. We have included 18 studies, 8 performed on miners, 3 on the general population and 7 on children, and the results have been structured using this classification. The results are inconclusive. An association between radon exposure and central nervous system tumors has been observed in some studies on miners, but not in others. The results observed in the general adult population and in children are also mixed, with some research evincing a statistically significant association and others showing no effect. We cannot conclude that there is a relationship between radon exposure and central nervous system tumors. The available studies are extremely heterogeneous in terms of design and populations studied. Further research is needed in this topic, particularly in the general population residing in areas with high levels of radon. Copyright © 2017 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

Con-Text: Text Detection for Fine-grained Object Classification.

PubMed

Karaoglu, Sezer; Tao, Ran; van Gemert, Jan C; Gevers, Theo

2017-05-24

This work focuses on fine-grained object classification using recognized scene text in natural images. While the state-of-the-art relies on visual cues only, this paper is the first work which proposes to combine textual and visual cues. Another novelty is the textual cue extraction. Unlike the state-of-the-art text detection methods, we focus more on the background instead of text regions. Once text regions are detected, they are further processed by two methods to perform text recognition i.e. ABBYY commercial OCR engine and a state-of-the-art character recognition algorithm. Then, to perform textual cue encoding, bi- and trigrams are formed between the recognized characters by considering the proposed spatial pairwise constraints. Finally, extracted visual and textual cues are combined for fine-grained classification. The proposed method is validated on four publicly available datasets: ICDAR03, ICDAR13, Con-Text and Flickr-logo. We improve the state-of-the-art end-to-end character recognition by a large margin of 15% on ICDAR03. We show that textual cues are useful in addition to visual cues for fine-grained classification. We show that textual cues are also useful for logo retrieval. Adding textual cues outperforms visual- and textual-only in fine-grained classification (70.7% to 60.3%) and logo retrieval (57.4% to 54.8%).

Using multi-terminology indexing for the assignment of MeSH descriptors to health resources in a French online catalogue.

PubMed

Pereira, Suzanne; Névéol, Aurélie; Kerdelhué, Gaétan; Serrot, Elisabeth; Joubert, Michel; Darmoni, Stéfan J

2008-11-06

To assist with the development of a French online quality-controlled health gateway(CISMeF), an automatic indexing tool assigning MeSH descriptors to medical text in French was created. The French Multi-Terminology Indexer (FMTI) relies on a multi-terminology approach involving four prominent medical terminologies and the mappings between them. In this paper,we compare lemmatization and stemming as methods to process French medical text for indexing. We also evaluate the multi-terminology approach implemented in F-MTI. The indexing strategies were assessed on a corpus of 18,814 resources indexed manually. There is little difference in the indexing performance when lemmatization or stemming is used. However, the multi-terminology approach outperforms indexing relying on a single terminology in terms of recall. F-MTI will soon be used in the CISMeF production environment and in a Health MultiTerminology Server in French.

Comparative effectiveness research designs: an analysis of terms and coverage in Medical Subject Headings (MeSH) and Emtree*†

PubMed Central

Bekhuis, Tanja; Demner-Fushman, Dina; Crowley, Rebecca S.

2013-01-01

Objectives: We analyzed the extent to which comparative effectiveness research (CER) organizations share terms for designs, analyzed coverage of CER designs in Medical Subject Headings (MeSH) and Emtree, and explored whether scientists use CER design terms. Methods: We developed local terminologies (LTs) and a CER design terminology by extracting terms in documents from five organizations. We defined coverage as the distribution over match type in MeSH and Emtree. We created a crosswalk by recording terms to which design terms mapped in both controlled vocabularies. We analyzed the hits for queries restricted to titles and abstracts to explore scientists' language. Results: Pairwise LT overlap ranged from 22.64% (12/53) to 75.61% (31/41). The CER design terminology (n = 78 terms) consisted of terms for primary study designs and a few terms useful for evaluating evidence, such as opinion paper and systematic review. Patterns of coverage were similar in MeSH and Emtree (gamma = 0.581, P = 0.002). Conclusions: Stakeholder terminologies vary, and terms are inconsistently covered in MeSH and Emtree. The CER design terminology and crosswalk may be useful for expert searchers. For partially mapped terms, queries could consist of free text for modifiers such as nonrandomized or interrupted added to broad or related controlled terms. PMID:23646024

Pharmacovigilance in children: detecting adverse drug reactions in routine electronic healthcare records. A systematic review.

PubMed

Black, Corri; Tagiyeva-Milne, Nara; Helms, Peter; Moir, Dorothy

2015-10-01

A systematic review of the literature published in English over 10 years was undertaken in order to describe the use of electronic healthcare data in the identification of potential adverse drug reactions (ADRs) in children. MEDLINE and EMBASE were searched using MESH headings and text words. Titles, keywords and abstracts were checked for age <18 years, potential ADRs and electronic healthcare data. Information extracted included age, data source, pharmacovigilance method, medicines and ADRs. Studies were quality assessed. From 14 804 titles, 314 had a full text review and 71 were included in the final review. Fifty were published in North America, 10 in Scandinavia. Study size ranged from less than 1000 children to more than 10 million. Sixty per cent of studies used data from one source. Comparative observational studies were most commonly reported (66.2%) with 15% using passive surveillance. Electronic healthcare data set linkage and the quality of the data source were poorly reported. ADRs were classified using the International Classification of Disease (ICD10). Multi-system reactions were most commonly studied, followed by central nervous system and mental and behavioural disorders. Vaccines were most frequently prescribed followed by corticosteroids, general anaesthetics and antidepressants. Routine electronic healthcare records were increasingly reported to be used for pharmacovigilance in children. This growing and important health protection activity could be enhanced by consistent reporting of studies to improve the identification, interpretation and generalizability of the evidence base. © 2015 The British Pharmacological Society.

Automated 3D closed surface segmentation: application to vertebral body segmentation in CT images.

PubMed

Liu, Shuang; Xie, Yiting; Reeves, Anthony P

2016-05-01

A fully automated segmentation algorithm, progressive surface resolution (PSR), is presented in this paper to determine the closed surface of approximately convex blob-like structures that are common in biomedical imaging. The PSR algorithm was applied to the cortical surface segmentation of 460 vertebral bodies on 46 low-dose chest CT images, which can be potentially used for automated bone mineral density measurement and compression fracture detection. The target surface is realized by a closed triangular mesh, which thereby guarantees the enclosure. The surface vertices of the triangular mesh representation are constrained along radial trajectories that are uniformly distributed in 3D angle space. The segmentation is accomplished by determining for each radial trajectory the location of its intersection with the target surface. The surface is first initialized based on an input high confidence boundary image and then resolved progressively based on a dynamic attraction map in an order of decreasing degree of evidence regarding the target surface location. For the visual evaluation, the algorithm achieved acceptable segmentation for 99.35 % vertebral bodies. Quantitative evaluation was performed on 46 vertebral bodies and achieved overall mean Dice coefficient of 0.939 (with max [Formula: see text] 0.957, min [Formula: see text] 0.906 and standard deviation [Formula: see text] 0.011) using manual annotations as the ground truth. Both visual and quantitative evaluations demonstrate encouraging performance of the PSR algorithm. This novel surface resolution strategy provides uniform angular resolution for the segmented surface with computation complexity and runtime that are linearly constrained by the total number of vertices of the triangular mesh representation.

Performance of search strategies to retrieve systematic reviews of diagnostic test accuracy from the Cochrane Library.

PubMed

Huang, Yuansheng; Yang, Zhirong; Wang, Jing; Zhuo, Lin; Li, Zhixia; Zhan, Siyan

2016-05-06

To compare the performance of search strategies to retrieve systematic reviews of diagnostic test accuracy from The Cochrane Library. Databases of CDSR and DARE in the Cochrane Library were searched for systematic reviews of diagnostic test accuracy published between 2008 and 2012 through nine search strategies. Each strategy consists of one group or combination of groups of searching filters about diagnostic test accuracy. Four groups of diagnostic filters were used. The Strategy combing all the filters was used as the reference to determine the sensitivity, precision, and the sensitivity x precision product for another eight Strategies. The reference Strategy retrieved 8029 records, of which 832 were eligible. The strategy only composed of MeSH terms about "accuracy measures" achieved the highest values in both precision (69.71%) and product (52.45%) with a moderate sensitivity (75.24%). The combination of MeSH terms and free text words about "accuracy measures" contributed little to increasing the sensitivity. Strategies composed of filters about "diagnosis" had similar sensitivity but lower precision and product to those composed of filters about "accuracy measures". MeSH term "exp'diagnosis' " achieved the lowest precision (9.78%) and product (7.91%), while its hyponym retrieved only half the number of records at the expense of missing 53 target articles. The precision was negatively correlated with sensitivities among the nine strategies. Compared to the filters about "diagnosis", the filters about "accuracy measures" achieved similar sensitivities but higher precision. When combining both terms, sensitivity of the strategy was enhanced obviously. The combination of MeSH terms and free text words about the same concept seemed to be meaningless for enhancing sensitivity. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

An automated machine vision system for the histological grading of cervical intraepithelial neoplasia (CIN).

PubMed

Keenan, S J; Diamond, J; McCluggage, W G; Bharucha, H; Thompson, D; Bartels, P H; Hamilton, P W

2000-11-01

The histological grading of cervical intraepithelial neoplasia (CIN) remains subjective, resulting in inter- and intra-observer variation and poor reproducibility in the grading of cervical lesions. This study has attempted to develop an objective grading system using automated machine vision. The architectural features of cervical squamous epithelium are quantitatively analysed using a combination of computerized digital image processing and Delaunay triangulation analysis; 230 images digitally captured from cases previously classified by a gynaecological pathologist included normal cervical squamous epithelium (n=30), koilocytosis (n=46), CIN 1 (n=52), CIN 2 (n=56), and CIN 3 (n=46). Intra- and inter-observer variation had kappa values of 0.502 and 0.415, respectively. A machine vision system was developed in KS400 macro programming language to segment and mark the centres of all nuclei within the epithelium. By object-oriented analysis of image components, the positional information of nuclei was used to construct a Delaunay triangulation mesh. Each mesh was analysed to compute triangle dimensions including the mean triangle area, the mean triangle edge length, and the number of triangles per unit area, giving an individual quantitative profile of measurements for each case. Discriminant analysis of the geometric data revealed the significant discriminatory variables from which a classification score was derived. The scoring system distinguished between normal and CIN 3 in 98.7% of cases and between koilocytosis and CIN 1 in 76.5% of cases, but only 62.3% of the CIN cases were classified into the correct group, with the CIN 2 group showing the highest rate of misclassification. Graphical plots of triangulation data demonstrated the continuum of morphological change from normal squamous epithelium to the highest grade of CIN, with overlapping of the groups originally defined by the pathologists. This study shows that automated location of nuclei in cervical biopsies using computerized image analysis is possible. Analysis of positional information enables quantitative evaluation of architectural features in CIN using Delaunay triangulation meshes, which is effective in the objective classification of CIN. This demonstrates the future potential of automated machine vision systems in diagnostic histopathology. Copyright 2000 John Wiley & Sons, Ltd.

Fluid mechanics based classification of the respiratory efficiency of several nasal cavities.

PubMed

Lintermann, Andreas; Meinke, Matthias; Schröder, Wolfgang

2013-11-01

The flow in the human nasal cavity is of great importance to understand rhinologic pathologies like impaired respiration or heating capabilities, a diminished sense of taste and smell, and the presence of dry mucous membranes. To numerically analyze this flow problem a highly efficient and scalable Thermal Lattice-BGK (TLBGK) solver is used, which is very well suited for flows in intricate geometries. The generation of the computational mesh is completely automatic and highly parallelized such that it can be executed efficiently on High Performance Computers (HPCs). An evaluation of the functionality of nasal cavities is based on an analysis of pressure drop, secondary flow structures, wall-shear stress distributions, and temperature variations from the nostrils to the pharynx. The results of the flow fields of three completely different nasal cavities allow their classification into ability groups and support the a priori decision process on surgical interventions. © 2013 Elsevier Ltd. All rights reserved.

Approach for Text Classification Based on the Similarity Measurement between Normal Cloud Models

PubMed Central

Dai, Jin; Liu, Xin

2014-01-01

The similarity between objects is the core research area of data mining. In order to reduce the interference of the uncertainty of nature language, a similarity measurement between normal cloud models is adopted to text classification research. On this basis, a novel text classifier based on cloud concept jumping up (CCJU-TC) is proposed. It can efficiently accomplish conversion between qualitative concept and quantitative data. Through the conversion from text set to text information table based on VSM model, the text qualitative concept, which is extraction from the same category, is jumping up as a whole category concept. According to the cloud similarity between the test text and each category concept, the test text is assigned to the most similar category. By the comparison among different text classifiers in different feature selection set, it fully proves that not only does CCJU-TC have a strong ability to adapt to the different text features, but also the classification performance is also better than the traditional classifiers. PMID:24711737

Classification of hepatocellular carcinoma stages from free-text clinical and radiology reports

PubMed Central

Yim, Wen-wai; Kwan, Sharon W; Johnson, Guy; Yetisgen, Meliha

2017-01-01

Cancer stage information is important for clinical research. However, they are not always explicitly noted in electronic medical records. In this paper, we present our work on automatic classification of hepatocellular carcinoma (HCC) stages from free-text clinical and radiology notes. To accomplish this, we defined 11 stage parameters used in the three HCC staging systems, American Joint Committee on Cancer (AJCC), Barcelona Clinic Liver Cancer (BCLC), and Cancer of the Liver Italian Program (CLIP). After aggregating stage parameters to the patient-level, the final stage classifications were achieved using an expert-created decision logic. Each stage parameter relevant for staging was extracted using several classification methods, e.g. sentence classification and automatic information structuring, to identify and normalize text as cancer stage parameter values. Stage parameter extraction for the test set performed at 0.81 F1. Cancer stage prediction for AJCC, BCLC, and CLIP stage classifications were 0.55, 0.50, and 0.43 F1.

Detection and Evaluation of Cheating on College Exams Using Supervised Classification

ERIC Educational Resources Information Center

Cavalcanti, Elmano Ramalho; Pires, Carlos Eduardo; Cavalcanti, Elmano Pontes; Pires, Vládia Freire

2012-01-01

Text mining has been used for various purposes, such as document classification and extraction of domain-specific information from text. In this paper we present a study in which text mining methodology and algorithms were properly employed for academic dishonesty (cheating) detection and evaluation on open-ended college exams, based on document…

Bibliographic Classification Theory and Text Linguistics: Aboutness Analysis, Intertextuality and the Cognitive Act of Classifying Documents.

ERIC Educational Resources Information Center

Beghtol, Clare

1986-01-01

Explicates a definition and theory of "aboutness" and aboutness analysis developed by text linguist van Dijk; explores implications of text linguistics for bibliographic classification theory; suggests the elements that a theory of the cognitive process of classifying documents needs to encompass; and delineates how people identify…

Comparisons and Selections of Features and Classifiers for Short Text Classification

NASA Astrophysics Data System (ADS)

Wang, Ye; Zhou, Zhi; Jin, Shan; Liu, Debin; Lu, Mi

2017-10-01

Short text is considerably different from traditional long text documents due to its shortness and conciseness, which somehow hinders the applications of conventional machine learning and data mining algorithms in short text classification. According to traditional artificial intelligence methods, we divide short text classification into three steps, namely preprocessing, feature selection and classifier comparison. In this paper, we have illustrated step-by-step how we approach our goals. Specifically, in feature selection, we compared the performance and robustness of the four methods of one-hot encoding, tf-idf weighting, word2vec and paragraph2vec, and in the classification part, we deliberately chose and compared Naive Bayes, Logistic Regression, Support Vector Machine, K-nearest Neighbor and Decision Tree as our classifiers. Then, we compared and analysed the classifiers horizontally with each other and vertically with feature selections. Regarding the datasets, we crawled more than 400,000 short text files from Shanghai and Shenzhen Stock Exchanges and manually labeled them into two classes, the big and the small. There are eight labels in the big class, and 59 labels in the small class.

Information Gain Based Dimensionality Selection for Classifying Text Documents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumidu Wijayasekara; Milos Manic; Miles McQueen

2013-06-01

Selecting the optimal dimensions for various knowledge extraction applications is an essential component of data mining. Dimensionality selection techniques are utilized in classification applications to increase the classification accuracy and reduce the computational complexity. In text classification, where the dimensionality of the dataset is extremely high, dimensionality selection is even more important. This paper presents a novel, genetic algorithm based methodology, for dimensionality selection in text mining applications that utilizes information gain. The presented methodology uses information gain of each dimension to change the mutation probability of chromosomes dynamically. Since the information gain is calculated a priori, the computational complexitymore » is not affected. The presented method was tested on a specific text classification problem and compared with conventional genetic algorithm based dimensionality selection. The results show an improvement of 3% in the true positives and 1.6% in the true negatives over conventional dimensionality selection methods.« less

Applications of information and communications technologies to public health: A scoping review using the MeSH term: "public health informatics".

PubMed

Bhattarai, Arjun Kumar; Zarrin, Aein; Lee, Joon

2017-01-01

To investigate the public health domains, key informatics concepts, and information and communications technologies (ICTs) applied in articles that are tagged with the MeSH term "public health informatics" and primarily focus on applying ICTs to public health. The MeSH term "public health informatics" was searched on MEDLINE-PubMed. The results of the search were then screened in two steps in order to only include articles about applying ICTs to public health problems. First, articles were screened based on their titles and abstracts. Second, a full-text review was conducted to ensure the relevance of the included articles. All articles were charted based on public health domain, information technology, article type, and informatics concept. 515 articles were included. Communicable disease monitoring (N=235), public health policy and research (N=201), and public health awareness (N=85) constituted the majority of the articles. Inconsistent results were found regarding the validity of syndromic surveillance and the effectiveness of PHI integration within the healthcare systems. PHI articles with an ICT focus cover a wide range of themes. Collectively, the included articles emphasized the need for further research in interoperability, data quality, appropriate data sources, accessible health information, and communication. The limitations of the study include:1) only one database was searched; 2) by using MeSH tags as a selection criterion, PHI articles without the "public health informatics" MeSH term were excluded. Due to the multi-disciplinary nature of PHI, MeSH identifiers were not assigned consistently. Current MeSH-tagged articles indicate that a comprehensive approach is required to integrate PHI into the healthcare system.

Trials of transvaginal mesh devices for pelvic organ prolapse: a systematic database review of the US FDA approval process.

PubMed

Heneghan, Carl J; Goldacre, Ben; Onakpoya, Igho; Aronson, Jeffrey K; Jefferson, Tom; Pluddemann, Annette; Mahtani, Kamal R

2017-12-06

Transvaginal mesh devices are approved in the USA by the Food and Drug Administration (FDA), through the 510(k) system. However, there is uncertainty about the benefit to harm balance of mesh approved for pelvic organ prolapse. We, therefore, assessed the evidence at the time of approval for transvaginal mesh products and the impact of safety studies the FDA mandated in 2012 because of emerging harms. We used FDA databases to determine the evidence for approval of transvaginal mesh. To create a 'family tree' of device equivalence, we used the 510(k) regulatory approval of the 1985 Mersilene Mesh (Ethicon) and the 1996 ProteGen Sling (Boston Scientific), searched for all subsequently related device approvals, and for the first published randomised trial evidence. We assessed compliance with all FDA 522 orders issued in 2012 requiring postmarketing surveillance studies. We found 61 devices whose approval ultimately relied on claimed equivalence to the Mersilene Mesh and the ProteGen Sling. We found no clinical trials evidence for these 61 devices at the time of approval. Publication of randomised clinical trials occurred at a median of 5 years after device approval (range 1-14 years). Analysis of 119 FDA 522 orders revealed that in 79 (66%) the manufacturer ceased market distribution of the device, and in 26 (22%) the manufacturer had changed the indication. Only seven studies (six cohorts and new randomised controlled trial) covering 11 orders were recruiting participants (none had reported outcomes). Transvaginal mesh products for pelvic organ prolapse have been approved on the basis of weak evidence over the last 20 years. Devices have inherited approval status from a few products. A publicly accessible registry of licensed invasive devices, with details of marketing status and linked evidence, should be created and maintained at the time of approval. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Learning From Short Text Streams With Topic Drifts.

PubMed

Li, Peipei; He, Lu; Wang, Haiyan; Hu, Xuegang; Zhang, Yuhong; Li, Lei; Wu, Xindong

2017-09-18

Short text streams such as search snippets and micro blogs have been popular on the Web with the emergence of social media. Unlike traditional normal text streams, these data present the characteristics of short length, weak signal, high volume, high velocity, topic drift, etc. Short text stream classification is hence a very challenging and significant task. However, this challenge has received little attention from the research community. Therefore, a new feature extension approach is proposed for short text stream classification with the help of a large-scale semantic network obtained from a Web corpus. It is built on an incremental ensemble classification model for efficiency. First, more semantic contexts based on the senses of terms in short texts are introduced to make up of the data sparsity using the open semantic network, in which all terms are disambiguated by their semantics to reduce the noise impact. Second, a concept cluster-based topic drifting detection method is proposed to effectively track hidden topic drifts. Finally, extensive studies demonstrate that as compared to several well-known concept drifting detection methods in data stream, our approach can detect topic drifts effectively, and it enables handling short text streams effectively while maintaining the efficiency as compared to several state-of-the-art short text classification approaches.

Simple-random-sampling-based multiclass text classification algorithm.

PubMed

Liu, Wuying; Wang, Lin; Yi, Mianzhu

2014-01-01

Multiclass text classification (MTC) is a challenging issue and the corresponding MTC algorithms can be used in many applications. The space-time overhead of the algorithms must be concerned about the era of big data. Through the investigation of the token frequency distribution in a Chinese web document collection, this paper reexamines the power law and proposes a simple-random-sampling-based MTC (SRSMTC) algorithm. Supported by a token level memory to store labeled documents, the SRSMTC algorithm uses a text retrieval approach to solve text classification problems. The experimental results on the TanCorp data set show that SRSMTC algorithm can achieve the state-of-the-art performance at greatly reduced space-time requirements.

Portable automatic text classification for adverse drug reaction detection via multi-corpus training.

PubMed

Sarker, Abeed; Gonzalez, Graciela

2015-02-01

Automatic detection of adverse drug reaction (ADR) mentions from text has recently received significant interest in pharmacovigilance research. Current research focuses on various sources of text-based information, including social media-where enormous amounts of user posted data is available, which have the potential for use in pharmacovigilance if collected and filtered accurately. The aims of this study are: (i) to explore natural language processing (NLP) approaches for generating useful features from text, and utilizing them in optimized machine learning algorithms for automatic classification of ADR assertive text segments; (ii) to present two data sets that we prepared for the task of ADR detection from user posted internet data; and (iii) to investigate if combining training data from distinct corpora can improve automatic classification accuracies. One of our three data sets contains annotated sentences from clinical reports, and the two other data sets, built in-house, consist of annotated posts from social media. Our text classification approach relies on generating a large set of features, representing semantic properties (e.g., sentiment, polarity, and topic), from short text nuggets. Importantly, using our expanded feature sets, we combine training data from different corpora in attempts to boost classification accuracies. Our feature-rich classification approach performs significantly better than previously published approaches with ADR class F-scores of 0.812 (previously reported best: 0.770), 0.538 and 0.678 for the three data sets. Combining training data from multiple compatible corpora further improves the ADR F-scores for the in-house data sets to 0.597 (improvement of 5.9 units) and 0.704 (improvement of 2.6 units) respectively. Our research results indicate that using advanced NLP techniques for generating information rich features from text can significantly improve classification accuracies over existing benchmarks. Our experiments illustrate the benefits of incorporating various semantic features such as topics, concepts, sentiments, and polarities. Finally, we show that integration of information from compatible corpora can significantly improve classification performance. This form of multi-corpus training may be particularly useful in cases where data sets are heavily imbalanced (e.g., social media data), and may reduce the time and costs associated with the annotation of data in the future. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Portable Automatic Text Classification for Adverse Drug Reaction Detection via Multi-corpus Training

PubMed Central

Gonzalez, Graciela

2014-01-01

Objective Automatic detection of Adverse Drug Reaction (ADR) mentions from text has recently received significant interest in pharmacovigilance research. Current research focuses on various sources of text-based information, including social media — where enormous amounts of user posted data is available, which have the potential for use in pharmacovigilance if collected and filtered accurately. The aims of this study are: (i) to explore natural language processing approaches for generating useful features from text, and utilizing them in optimized machine learning algorithms for automatic classification of ADR assertive text segments; (ii) to present two data sets that we prepared for the task of ADR detection from user posted internet data; and (iii) to investigate if combining training data from distinct corpora can improve automatic classification accuracies. Methods One of our three data sets contains annotated sentences from clinical reports, and the two other data sets, built in-house, consist of annotated posts from social media. Our text classification approach relies on generating a large set of features, representing semantic properties (e.g., sentiment, polarity, and topic), from short text nuggets. Importantly, using our expanded feature sets, we combine training data from different corpora in attempts to boost classification accuracies. Results Our feature-rich classification approach performs significantly better than previously published approaches with ADR class F-scores of 0.812 (previously reported best: 0.770), 0.538 and 0.678 for the three data sets. Combining training data from multiple compatible corpora further improves the ADR F-scores for the in-house data sets to 0.597 (improvement of 5.9 units) and 0.704 (improvement of 2.6 units) respectively. Conclusions Our research results indicate that using advanced NLP techniques for generating information rich features from text can significantly improve classification accuracies over existing benchmarks. Our experiments illustrate the benefits of incorporating various semantic features such as topics, concepts, sentiments, and polarities. Finally, we show that integration of information from compatible corpora can significantly improve classification performance. This form of multi-corpus training may be particularly useful in cases where data sets are heavily imbalanced (e.g., social media data), and may reduce the time and costs associated with the annotation of data in the future. PMID:25451103

Efficient chemical-disease identification and relationship extraction using Wikipedia to improve recall

PubMed Central

Lowe, Daniel M.; O’Boyle, Noel M.; Sayle, Roger A.

2016-01-01

Awareness of the adverse effects of chemicals is important in biomedical research and healthcare. Text mining can allow timely and low-cost extraction of this knowledge from the biomedical literature. We extended our text mining solution, LeadMine, to identify diseases and chemical-induced disease relationships (CIDs). LeadMine is a dictionary/grammar-based entity recognizer and was used to recognize and normalize both chemicals and diseases to Medical Subject Headings (MeSH) IDs. The disease lexicon was obtained from three sources: MeSH, the Disease Ontology and Wikipedia. The Wikipedia dictionary was derived from pages with a disease/symptom box, or those where the page title appeared in the lexicon. Composite entities (e.g. heart and lung disease) were detected and mapped to their composite MeSH IDs. For CIDs, we developed a simple pattern-based system to find relationships within the same sentence. Our system was evaluated in the BioCreative V Chemical–Disease Relation task and achieved very good results for both disease concept ID recognition (F1-score: 86.12%) and CIDs (F1-score: 52.20%) on the test set. As our system was over an order of magnitude faster than other solutions evaluated on the task, we were able to apply the same system to the entirety of MEDLINE allowing us to extract a collection of over 250 000 distinct CIDs. PMID:27060160

Assessment of Synthetic Glue for Mesh Attachment in Laparoscopic Sacrocolpopexy: A Prospective Multicenter Pilot Study.

PubMed

Lamblin, Gery; Dubernard, Gil; de Saint Hilaire, Pierre; Jacquot, Franck; Chabert, Philippe; Chene, Gautier; Golfier, François

2017-01-01

To assess the anatomic efficacy and safety of synthetic glue to fix prosthetic material in laparoscopic sacrocolpopexy. A 1-year follow-up in a prospective multicenter pilot study between November 2013 and November 2014 (Canadian Task Force Classification II-2). An academic urogynecology research hospital. Seventy consecutive patients with Pelvic Organ Prolapse Quantification stage ≥3 anterior and/or medial prolapse underwent laparoscopic sacrocolpopexy. All women underwent laparoscopic sacrocolpopexy with the same standardized technique using a synthetic surgical glue to fix anterior and posterior meshes. Patients were followed up at 1 month and 1 year, with anatomic and functional assessment (Pelvic Floor Distress Inventory-20, Pelvic Floor Impact Questionnaire-7, and Pelvic Organ Prolapse/Urinary Incontinence Sexual Questionnaire-12). Anatomic success was defined as 1-year Pelvic Organ Prolapse Quantification stage ≤1. Sixty-six patients were included; the mean age was 56.7 ± 1.2 years. The mean operative time was 145 ± 5 minutes. The mean glue fixation time was less than 2 minutes for both anterior and posterior meshes. The 1-year anatomic success rate was 87.5% in the anterior compartment (Ba at -2.3 cm, p < .0001) and 95.3% in the medial compartment (point C at -6.1 cm, p < .0001). There were no intra- or postoperative complications and no cases of mesh exposure; 5 cases of mesh shrinkage (7.8%) were observed at 1 year. The postoperative urinary stress incontinence rate was 29.7% at 1 year. Eight patients (12.1%) underwent revision surgery with transobturator tape. All quality of life scores showed significant improvement (p < .0001) at 1 year. Synthetic glue attachment of prosthetic material in laparoscopic sacrocolpopexy proved straightforward, safe, time-saving, and effective at 1 year. Prospective randomized studies will be needed to confirm the long-term benefit. Copyright © 2016 AAGL. Published by Elsevier Inc. All rights reserved.

Text Extraction from Scene Images by Character Appearance and Structure Modeling

PubMed Central

Yi, Chucai; Tian, Yingli

2012-01-01

In this paper, we propose a novel algorithm to detect text information from natural scene images. Scene text classification and detection are still open research topics. Our proposed algorithm is able to model both character appearance and structure to generate representative and discriminative text descriptors. The contributions of this paper include three aspects: 1) a new character appearance model by a structure correlation algorithm which extracts discriminative appearance features from detected interest points of character samples; 2) a new text descriptor based on structons and correlatons, which model character structure by structure differences among character samples and structure component co-occurrence; and 3) a new text region localization method by combining color decomposition, character contour refinement, and string line alignment to localize character candidates and refine detected text regions. We perform three groups of experiments to evaluate the effectiveness of our proposed algorithm, including text classification, text detection, and character identification. The evaluation results on benchmark datasets demonstrate that our algorithm achieves the state-of-the-art performance on scene text classification and detection, and significantly outperforms the existing algorithms for character identification. PMID:23316111

Statistical text classifier to detect specific type of medical incidents.

PubMed

Wong, Zoie Shui-Yee; Akiyama, Masanori

2013-01-01

WHO Patient Safety has put focus to increase the coherence and expressiveness of patient safety classification with the foundation of International Classification for Patient Safety (ICPS). Text classification and statistical approaches has showed to be successful to identifysafety problems in the Aviation industryusing incident text information. It has been challenging to comprehend the taxonomy of medical incidents in a structured manner. Independent reporting mechanisms for patient safety incidents have been established in the UK, Canada, Australia, Japan, Hong Kong etc. This research demonstrates the potential to construct statistical text classifiers to detect specific type of medical incidents using incident text data. An illustrative example for classifying look-alike sound-alike (LASA) medication incidents using structured text from 227 advisories related to medication errors from Global Patient Safety Alerts (GPSA) is shown in this poster presentation. The classifier was built using logistic regression model. ROC curve and the AUC value indicated that this is a satisfactory good model.

3D shape decomposition and comparison for gallbladder modeling

NASA Astrophysics Data System (ADS)

Huang, Weimin; Zhou, Jiayin; Liu, Jiang; Zhang, Jing; Yang, Tao; Su, Yi; Law, Gim Han; Chui, Chee Kong; Chang, Stephen

2011-03-01

This paper presents an approach to gallbladder shape comparison by using 3D shape modeling and decomposition. The gallbladder models can be used for shape anomaly analysis and model comparison and selection in image guided robotic surgical training, especially for laparoscopic cholecystectomy simulation. The 3D shape of a gallbladder is first represented as a surface model, reconstructed from the contours segmented in CT data by a scheme of propagation based voxel learning and classification. To better extract the shape feature, the surface mesh is further down-sampled by a decimation filter and smoothed by a Taubin algorithm, followed by applying an advancing front algorithm to further enhance the regularity of the mesh. Multi-scale curvatures are then computed on the regularized mesh for the robust saliency landmark localization on the surface. The shape decomposition is proposed based on the saliency landmarks and the concavity, measured by the distance from the surface point to the convex hull. With a given tolerance the 3D shape can be decomposed and represented as 3D ellipsoids, which reveal the shape topology and anomaly of a gallbladder. The features based on the decomposed shape model are proposed for gallbladder shape comparison, which can be used for new model selection. We have collected 19 sets of abdominal CT scan data with gallbladders, some shown in normal shape and some in abnormal shapes. The experiments have shown that the decomposed shapes reveal important topology features.

Using multi-terminology indexing for the assignment of MeSH descriptors to health resources in a French online catalogue

PubMed Central

Pereira, Suzanne; Névéol, Aurélie; Kerdelhué, Gaétan; Serrot, Elisabeth; Joubert, Michel; Darmoni, Stéfan J.

2008-01-01

Background: To assist with the development of a French online quality-controlled health gateway (CISMeF), an automatic indexing tool assigning MeSH descriptors to medical text in French was created. The French Multi-Terminology Indexer (F-MTI) relies on a multi-terminology approach involving four prominent medical terminologies and the mappings between them. Objective: In this paper, we compare lemmatization and stemming as methods to process French medical text for indexing. We also evaluate the multi-terminology approach implemented in F-MTI. Methods: The indexing strategies were assessed on a corpus of 18,814 resources indexed manually. Results: There is little difference in the indexing performance when lemmatization or stemming is used. However, the multi-terminology approach outperforms indexing relying on a single terminology in terms of recall. Conclusion: F-MTI will soon be used in the CISMeF production environment and in a Health MultiTerminology Server in French. PMID:18998933

A Recent Advance in the Automatic Indexing of the Biomedical Literature

PubMed Central

Névéol, Aurélie; Shooshan, Sonya E.; Humphrey, Susanne M.; Mork, James G.; Aronson, Alan R.

2009-01-01

The volume of biomedical literature has experienced explosive growth in recent years. This is reflected in the corresponding increase in the size of MEDLINE®, the largest bibliographic database of biomedical citations. Indexers at the U.S. National Library of Medicine (NLM) need efficient tools to help them accommodate the ensuing workload. After reviewing issues in the automatic assignment of Medical Subject Headings (MeSH® terms) to biomedical text, we focus more specifically on the new subheading attachment feature for NLM’s Medical Text Indexer (MTI). Natural Language Processing, statistical, and machine learning methods of producing automatic MeSH main heading/subheading pair recommendations were assessed independently and combined. The best combination achieves 48% precision and 30% recall. After validation by NLM indexers, a suitable combination of the methods presented in this paper was integrated into MTI as a subheading attachment feature producing MeSH indexing recommendations compliant with current state-of-the-art indexing practice. PMID:19166973

Skull Base Erosion Resulting From Primary Tumors of the Temporomandibular Joint and Skull Base Region: Our Classification and Reconstruction Experience.

PubMed

Chen, Min-Jie; Yang, Chi; Zheng, Ji-Si; Bai, Guo; Han, Zi-Xiang; Wang, Yi-Wen

2018-06-01

We sought to introduce our classification and reconstruction protocol for skull base erosions in the temporomandibular joint and skull base region. Patients with neoplasms in the temporomandibular joint and skull base region treated from January 2006 to March 2017 were reviewed. Skull base erosion was classified into 3 types according to the size of the defect. We included 33 patients, of whom 5 (15.2%) had type I defects (including 3 in whom free fat grafts were placed and 2 in whom deep temporal fascial fat flaps were placed). There were 8 patients (24.2%) with type II defects, all of whom received deep temporal fascial fat flaps. A total of 20 patients (60.6%) had type III defects, including 17 in whom autogenous bone grafts were placed, 1 in whom titanium mesh was placed, and 2 who received total alloplastic joints. The mean follow-up period was 50 months. All of the patients exhibited stable occlusion and good facial symmetry. No recurrence was noted. Our classification and reconstruction principles allowed reliable morpho-functional skull base reconstruction. Copyright © 2018 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Screening for childhood strabismus by primary care physicians.

PubMed Central

Weinstock, V. M.; Weinstock, D. J.; Kraft, S. P.

1998-01-01

OBJECTIVE: To review the clinical classification of strabismus, to describe the timing and method of strabismus screening examinations, and to discuss the principles of treatment. QUALITY OF EVIDENCE: Current literature (1983 to 1995) was searched via MEDLINE using the MeSH headings strabismus, ocular motility disorders, and amblyopia. Articles were selected based on their date of publication, clinical relevance, and availability. Preference was given to more recent articles, articles with large numbers of subjects, and well-designed cohort studies. Official recommendations from academic groups were analyzed. Descriptions of clinical tests and their illustrations are based on classic texts. MAIN FINDINGS: Primary care physicians should screen all low-risk children. High-risk children (low birth weight, family history of strabismus, congenital ocular abnormality, or systemic conditions with vision-threatening ocular manifestations) should be referred to an ophthalmologist for screening. Screening should be performed in the neonatal period, at 6 months, and at 3 years (Grade A recommendation), as well as at 5 to 6 years (Grade B recommendation). Screening examination includes inspection, examining visual acuity, determining pupillary reactions, checking ocular alignment, testing eye movements, and ophthalmoscopy. CONCLUSIONS: Primary care physicians are essential to early detection of strabismus and amblyopia. Early detection can help minimize visual dysfunction, allow for normal development of binocular vision and depth perception, and prevent psychosocial dysfunction. PMID:9512837

A stylistic classification of Russian-language texts based on the random walk model

NASA Astrophysics Data System (ADS)

Kramarenko, A. A.; Nekrasov, K. A.; Filimonov, V. V.; Zhivoderov, A. A.; Amieva, A. A.

2017-09-01

A formal approach to text analysis is suggested that is based on the random walk model. The frequencies and reciprocal positions of the vowel letters are matched up by a process of quasi-particle migration. Statistically significant difference in the migration parameters for the texts of different functional styles is found. Thus, a possibility of classification of texts using the suggested method is demonstrated. Five groups of the texts are singled out that can be distinguished from one another by the parameters of the quasi-particle migration process.

Research on aviation unsafe incidents classification with improved TF-IDF algorithm

NASA Astrophysics Data System (ADS)

Wang, Yanhua; Zhang, Zhiyuan; Huo, Weigang

2016-05-01

The text content of Aviation Safety Confidential Reports contains a large number of valuable information. Term frequency-inverse document frequency algorithm is commonly used in text analysis, but it does not take into account the sequential relationship of the words in the text and its role in semantic expression. According to the seven category labels of civil aviation unsafe incidents, aiming at solving the problems of TF-IDF algorithm, this paper improved TF-IDF algorithm based on co-occurrence network; established feature words extraction and words sequential relations for classified incidents. Aviation domain lexicon was used to improve the accuracy rate of classification. Feature words network model was designed for multi-documents unsafe incidents classification, and it was used in the experiment. Finally, the classification accuracy of improved algorithm was verified by the experiments.

Emotion models for textual emotion classification

NASA Astrophysics Data System (ADS)

Bruna, O.; Avetisyan, H.; Holub, J.

2016-11-01

This paper deals with textual emotion classification which gained attention in recent years. Emotion classification is used in user experience, product evaluation, national security, and tutoring applications. It attempts to detect the emotional content in the input text and based on different approaches establish what kind of emotional content is present, if any. Textual emotion classification is the most difficult to handle, since it relies mainly on linguistic resources and it introduces many challenges to assignment of text to emotion represented by a proper model. A crucial part of each emotion detector is emotion model. Focus of this paper is to introduce emotion models used for classification. Categorical and dimensional models of emotion are explained and some more advanced approaches are mentioned.

Multi-label literature classification based on the Gene Ontology graph.

PubMed

Jin, Bo; Muller, Brian; Zhai, Chengxiang; Lu, Xinghua

2008-12-08

The Gene Ontology is a controlled vocabulary for representing knowledge related to genes and proteins in a computable form. The current effort of manually annotating proteins with the Gene Ontology is outpaced by the rate of accumulation of biomedical knowledge in literature, which urges the development of text mining approaches to facilitate the process by automatically extracting the Gene Ontology annotation from literature. The task is usually cast as a text classification problem, and contemporary methods are confronted with unbalanced training data and the difficulties associated with multi-label classification. In this research, we investigated the methods of enhancing automatic multi-label classification of biomedical literature by utilizing the structure of the Gene Ontology graph. We have studied three graph-based multi-label classification algorithms, including a novel stochastic algorithm and two top-down hierarchical classification methods for multi-label literature classification. We systematically evaluated and compared these graph-based classification algorithms to a conventional flat multi-label algorithm. The results indicate that, through utilizing the information from the structure of the Gene Ontology graph, the graph-based multi-label classification methods can significantly improve predictions of the Gene Ontology terms implied by the analyzed text. Furthermore, the graph-based multi-label classifiers are capable of suggesting Gene Ontology annotations (to curators) that are closely related to the true annotations even if they fail to predict the true ones directly. A software package implementing the studied algorithms is available for the research community. Through utilizing the information from the structure of the Gene Ontology graph, the graph-based multi-label classification methods have better potential than the conventional flat multi-label classification approach to facilitate protein annotation based on the literature.

Comparative Analysis of Document level Text Classification Algorithms using R

NASA Astrophysics Data System (ADS)

Syamala, Maganti; Nalini, N. J., Dr; Maguluri, Lakshamanaphaneendra; Ragupathy, R., Dr.

2017-08-01

From the past few decades there has been tremendous volumes of data available in Internet either in structured or unstructured form. Also, there is an exponential growth of information on Internet, so there is an emergent need of text classifiers. Text mining is an interdisciplinary field which draws attention on information retrieval, data mining, machine learning, statistics and computational linguistics. And to handle this situation, a wide range of supervised learning algorithms has been introduced. Among all these K-Nearest Neighbor(KNN) is efficient and simplest classifier in text classification family. But KNN suffers from imbalanced class distribution and noisy term features. So, to cope up with this challenge we use document based centroid dimensionality reduction(CentroidDR) using R Programming. By combining these two text classification techniques, KNN and Centroid classifiers, we propose a scalable and effective flat classifier, called MCenKNN which works well substantially better than CenKNN.

Efficient chemical-disease identification and relationship extraction using Wikipedia to improve recall.

PubMed

Lowe, Daniel M; O'Boyle, Noel M; Sayle, Roger A

2016-01-01

Awareness of the adverse effects of chemicals is important in biomedical research and healthcare. Text mining can allow timely and low-cost extraction of this knowledge from the biomedical literature. We extended our text mining solution, LeadMine, to identify diseases and chemical-induced disease relationships (CIDs). LeadMine is a dictionary/grammar-based entity recognizer and was used to recognize and normalize both chemicals and diseases to Medical Subject Headings (MeSH) IDs. The disease lexicon was obtained from three sources: MeSH, the Disease Ontology and Wikipedia. The Wikipedia dictionary was derived from pages with a disease/symptom box, or those where the page title appeared in the lexicon. Composite entities (e.g. heart and lung disease) were detected and mapped to their composite MeSH IDs. For CIDs, we developed a simple pattern-based system to find relationships within the same sentence. Our system was evaluated in the BioCreative V Chemical-Disease Relation task and achieved very good results for both disease concept ID recognition (F1-score: 86.12%) and CIDs (F1-score: 52.20%) on the test set. As our system was over an order of magnitude faster than other solutions evaluated on the task, we were able to apply the same system to the entirety of MEDLINE allowing us to extract a collection of over 250 000 distinct CIDs. © The Author(s) 2016. Published by Oxford University Press.

Building a common pipeline for rule-based document classification.

PubMed

Patterson, Olga V; Ginter, Thomas; DuVall, Scott L

2013-01-01

Instance-based classification of clinical text is a widely used natural language processing task employed as a step for patient classification, document retrieval, or information extraction. Rule-based approaches rely on concept identification and context analysis in order to determine the appropriate class. We propose a five-step process that enables even small research teams to develop simple but powerful rule-based NLP systems by taking advantage of a common UIMA AS based pipeline for classification. Our proposed methodology coupled with the general-purpose solution provides researchers with access to the data locked in clinical text in cases of limited human resources and compact timelines.

Short text sentiment classification based on feature extension and ensemble classifier

NASA Astrophysics Data System (ADS)

Liu, Yang; Zhu, Xie

2018-05-01

With the rapid development of Internet social media, excavating the emotional tendencies of the short text information from the Internet, the acquisition of useful information has attracted the attention of researchers. At present, the commonly used can be attributed to the rule-based classification and statistical machine learning classification methods. Although micro-blog sentiment analysis has made good progress, there still exist some shortcomings such as not highly accurate enough and strong dependence from sentiment classification effect. Aiming at the characteristics of Chinese short texts, such as less information, sparse features, and diverse expressions, this paper considers expanding the original text by mining related semantic information from the reviews, forwarding and other related information. First, this paper uses Word2vec to compute word similarity to extend the feature words. And then uses an ensemble classifier composed of SVM, KNN and HMM to analyze the emotion of the short text of micro-blog. The experimental results show that the proposed method can make good use of the comment forwarding information to extend the original features. Compared with the traditional method, the accuracy, recall and F1 value obtained by this method have been improved.

FROM2D to 3d Supervised Segmentation and Classification for Cultural Heritage Applications

NASA Astrophysics Data System (ADS)

Grilli, E.; Dininno, D.; Petrucci, G.; Remondino, F.

2018-05-01

The digital management of architectural heritage information is still a complex problem, as a heritage object requires an integrated representation of various types of information in order to develop appropriate restoration or conservation strategies. Currently, there is extensive research focused on automatic procedures of segmentation and classification of 3D point clouds or meshes, which can accelerate the study of a monument and integrate it with heterogeneous information and attributes, useful to characterize and describe the surveyed object. The aim of this study is to propose an optimal, repeatable and reliable procedure to manage various types of 3D surveying data and associate them with heterogeneous information and attributes to characterize and describe the surveyed object. In particular, this paper presents an approach for classifying 3D heritage models, starting from the segmentation of their textures based on supervised machine learning methods. Experimental results run on three different case studies demonstrate that the proposed approach is effective and with many further potentials.

A Novel Feature Selection Technique for Text Classification Using Naïve Bayes.

PubMed

Dey Sarkar, Subhajit; Goswami, Saptarsi; Agarwal, Aman; Aktar, Javed

2014-01-01

With the proliferation of unstructured data, text classification or text categorization has found many applications in topic classification, sentiment analysis, authorship identification, spam detection, and so on. There are many classification algorithms available. Naïve Bayes remains one of the oldest and most popular classifiers. On one hand, implementation of naïve Bayes is simple and, on the other hand, this also requires fewer amounts of training data. From the literature review, it is found that naïve Bayes performs poorly compared to other classifiers in text classification. As a result, this makes the naïve Bayes classifier unusable in spite of the simplicity and intuitiveness of the model. In this paper, we propose a two-step feature selection method based on firstly a univariate feature selection and then feature clustering, where we use the univariate feature selection method to reduce the search space and then apply clustering to select relatively independent feature sets. We demonstrate the effectiveness of our method by a thorough evaluation and comparison over 13 datasets. The performance improvement thus achieved makes naïve Bayes comparable or superior to other classifiers. The proposed algorithm is shown to outperform other traditional methods like greedy search based wrapper or CFS.

Localizing text in scene images by boundary clustering, stroke segmentation, and string fragment classification.

PubMed

Yi, Chucai; Tian, Yingli

2012-09-01

In this paper, we propose a novel framework to extract text regions from scene images with complex backgrounds and multiple text appearances. This framework consists of three main steps: boundary clustering (BC), stroke segmentation, and string fragment classification. In BC, we propose a new bigram-color-uniformity-based method to model both text and attachment surface, and cluster edge pixels based on color pairs and spatial positions into boundary layers. Then, stroke segmentation is performed at each boundary layer by color assignment to extract character candidates. We propose two algorithms to combine the structural analysis of text stroke with color assignment and filter out background interferences. Further, we design a robust string fragment classification based on Gabor-based text features. The features are obtained from feature maps of gradient, stroke distribution, and stroke width. The proposed framework of text localization is evaluated on scene images, born-digital images, broadcast video images, and images of handheld objects captured by blind persons. Experimental results on respective datasets demonstrate that the framework outperforms state-of-the-art localization algorithms.

Using Computational Text Classification for Qualitative Research and Evaluation in Extension

ERIC Educational Resources Information Center

Smith, Justin G.; Tissing, Reid

2018-01-01

This article introduces a process for computational text classification that can be used in a variety of qualitative research and evaluation settings. The process leverages supervised machine learning based on an implementation of a multinomial Bayesian classifier. Applied to a community of inquiry framework, the algorithm was used to identify…

Using complex networks for text classification: Discriminating informative and imaginative documents

NASA Astrophysics Data System (ADS)

de Arruda, Henrique F.; Costa, Luciano da F.; Amancio, Diego R.

2016-01-01

Statistical methods have been widely employed in recent years to grasp many language properties. The application of such techniques have allowed an improvement of several linguistic applications, such as machine translation and document classification. In the latter, many approaches have emphasised the semantical content of texts, as is the case of bag-of-word language models. These approaches have certainly yielded reasonable performance. However, some potential features such as the structural organization of texts have been used only in a few studies. In this context, we probe how features derived from textual structure analysis can be effectively employed in a classification task. More specifically, we performed a supervised classification aiming at discriminating informative from imaginative documents. Using a networked model that describes the local topological/dynamical properties of function words, we achieved an accuracy rate of up to 95%, which is much higher than similar networked approaches. A systematic analysis of feature relevance revealed that symmetry and accessibility measurements are among the most prominent network measurements. Our results suggest that these measurements could be used in related language applications, as they play a complementary role in characterising texts.

Classification of forensic autopsy reports through conceptual graph-based document representation model.

PubMed

Mujtaba, Ghulam; Shuib, Liyana; Raj, Ram Gopal; Rajandram, Retnagowri; Shaikh, Khairunisa; Al-Garadi, Mohammed Ali

2018-06-01

Text categorization has been used extensively in recent years to classify plain-text clinical reports. This study employs text categorization techniques for the classification of open narrative forensic autopsy reports. One of the key steps in text classification is document representation. In document representation, a clinical report is transformed into a format that is suitable for classification. The traditional document representation technique for text categorization is the bag-of-words (BoW) technique. In this study, the traditional BoW technique is ineffective in classifying forensic autopsy reports because it merely extracts frequent but discriminative features from clinical reports. Moreover, this technique fails to capture word inversion, as well as word-level synonymy and polysemy, when classifying autopsy reports. Hence, the BoW technique suffers from low accuracy and low robustness unless it is improved with contextual and application-specific information. To overcome the aforementioned limitations of the BoW technique, this research aims to develop an effective conceptual graph-based document representation (CGDR) technique to classify 1500 forensic autopsy reports from four (4) manners of death (MoD) and sixteen (16) causes of death (CoD). Term-based and Systematized Nomenclature of Medicine-Clinical Terms (SNOMED CT) based conceptual features were extracted and represented through graphs. These features were then used to train a two-level text classifier. The first level classifier was responsible for predicting MoD. In addition, the second level classifier was responsible for predicting CoD using the proposed conceptual graph-based document representation technique. To demonstrate the significance of the proposed technique, its results were compared with those of six (6) state-of-the-art document representation techniques. Lastly, this study compared the effects of one-level classification and two-level classification on the experimental results. The experimental results indicated that the CGDR technique achieved 12% to 15% improvement in accuracy compared with fully automated document representation baseline techniques. Moreover, two-level classification obtained better results compared with one-level classification. The promising results of the proposed conceptual graph-based document representation technique suggest that pathologists can adopt the proposed system as their basis for second opinion, thereby supporting them in effectively determining CoD. Copyright © 2018 Elsevier Inc. All rights reserved.

The Canadian Hydrological Model (CHM): A multi-scale, variable-complexity hydrological model for cold regions

NASA Astrophysics Data System (ADS)

Marsh, C.; Pomeroy, J. W.; Wheater, H. S.

2016-12-01

There is a need for hydrological land surface schemes that can link to atmospheric models, provide hydrological prediction at multiple scales and guide the development of multiple objective water predictive systems. Distributed raster-based models suffer from an overrepresentation of topography, leading to wasted computational effort that increases uncertainty due to greater numbers of parameters and initial conditions. The Canadian Hydrological Model (CHM) is a modular, multiphysics, spatially distributed modelling framework designed for representing hydrological processes, including those that operate in cold-regions. Unstructured meshes permit variable spatial resolution, allowing coarse resolutions at low spatial variability and fine resolutions as required. Model uncertainty is reduced by lessening the necessary computational elements relative to high-resolution rasters. CHM uses a novel multi-objective approach for unstructured triangular mesh generation that fulfills hydrologically important constraints (e.g., basin boundaries, water bodies, soil classification, land cover, elevation, and slope/aspect). This provides an efficient spatial representation of parameters and initial conditions, as well as well-formed and well-graded triangles that are suitable for numerical discretization. CHM uses high-quality open source libraries and high performance computing paradigms to provide a framework that allows for integrating current state-of-the-art process algorithms. The impact of changes to model structure, including individual algorithms, parameters, initial conditions, driving meteorology, and spatial/temporal discretization can be easily tested. Initial testing of CHM compared spatial scales and model complexity for a spring melt period at a sub-arctic mountain basin. The meshing algorithm reduced the total number of computational elements and preserved the spatial heterogeneity of predictions.

Automatic topic identification of health-related messages in online health community using text classification.

PubMed

Lu, Yingjie

2013-01-01

To facilitate patient involvement in online health community and obtain informative support and emotional support they need, a topic identification approach was proposed in this paper for identifying automatically topics of the health-related messages in online health community, thus assisting patients in reaching the most relevant messages for their queries efficiently. Feature-based classification framework was presented for automatic topic identification in our study. We first collected the messages related to some predefined topics in a online health community. Then we combined three different types of features, n-gram-based features, domain-specific features and sentiment features to build four feature sets for health-related text representation. Finally, three different text classification techniques, C4.5, Naïve Bayes and SVM were adopted to evaluate our topic classification model. By comparing different feature sets and different classification techniques, we found that n-gram-based features, domain-specific features and sentiment features were all considered to be effective in distinguishing different types of health-related topics. In addition, feature reduction technique based on information gain was also effective to improve the topic classification performance. In terms of classification techniques, SVM outperformed C4.5 and Naïve Bayes significantly. The experimental results demonstrated that the proposed approach could identify the topics of online health-related messages efficiently.

Risk factors for bladder cancer: challenges of conducting a literature search using PubMed.

PubMed

Joshi, Ashish; Preslan, Elicia

2011-04-01

The objective of this study was to assess the risk factors for bladder cancer using PubMed articles from January 2000 to December 2009. The study also aimed to describe the challenges encountered in the methodology of a literature search for bladder cancer risk factors using PubMed. Twenty-six categories of risk factors for bladder cancer were identified using the National Cancer Institute Web site and the Medical Subject Headings (MeSH) Web site. A total of 1,338 PubMed searches were run using the term "urinary bladder cancer" and a risk factor term (e.g., "cigarette smoking") and were screened to identify 260 articles for final analysis. The search strategy had an overall precision of 3.42 percent, relative recall of 12.64 percent, and an F-measure of 5.39 percent. Although search terms derived from MeSH had the highest overall precision and recall, the differences did not reach significance, which indicates that for generalized, free-text searches of the PubMed database, the searchers' own terms are generally as effective as MeSH terms.

Does the Use of a Classification for Nursing Diagnoses Affect Nursing Students’ Choice of Nursing Interventions?

PubMed Central

Falk, Joakim; Björvell, Catrin

2012-01-01

The Swedish health care system stands before an implementation of standardized language. The first classification of nursing diagnoses translated into Swedish, The NANDA, was released in January 2011. The aim of the present study was to examine whether the usage of the NANDA classification affected nursing students’ choice of nursing interventions. Thirty-three nursing students in a clinical setting were divided into two groups. The intervention group had access to the NANDA classification text book, while the comparison group did not. In total 78 nursing assessments were performed and 218 nursing interventions initiated. The principle findings show that there were no statistical significant differences between the groups regarding the amount, quality or category of nursing interventions when using the NANDA classification compared to free text format nursing diagnoses. PMID:24199065

PDF text classification to leverage information extraction from publication reports.

PubMed

Bui, Duy Duc An; Del Fiol, Guilherme; Jonnalagadda, Siddhartha

2016-06-01

Data extraction from original study reports is a time-consuming, error-prone process in systematic review development. Information extraction (IE) systems have the potential to assist humans in the extraction task, however majority of IE systems were not designed to work on Portable Document Format (PDF) document, an important and common extraction source for systematic review. In a PDF document, narrative content is often mixed with publication metadata or semi-structured text, which add challenges to the underlining natural language processing algorithm. Our goal is to categorize PDF texts for strategic use by IE systems. We used an open-source tool to extract raw texts from a PDF document and developed a text classification algorithm that follows a multi-pass sieve framework to automatically classify PDF text snippets (for brevity, texts) into TITLE, ABSTRACT, BODYTEXT, SEMISTRUCTURE, and METADATA categories. To validate the algorithm, we developed a gold standard of PDF reports that were included in the development of previous systematic reviews by the Cochrane Collaboration. In a two-step procedure, we evaluated (1) classification performance, and compared it with machine learning classifier, and (2) the effects of the algorithm on an IE system that extracts clinical outcome mentions. The multi-pass sieve algorithm achieved an accuracy of 92.6%, which was 9.7% (p<0.001) higher than the best performing machine learning classifier that used a logistic regression algorithm. F-measure improvements were observed in the classification of TITLE (+15.6%), ABSTRACT (+54.2%), BODYTEXT (+3.7%), SEMISTRUCTURE (+34%), and MEDADATA (+14.2%). In addition, use of the algorithm to filter semi-structured texts and publication metadata improved performance of the outcome extraction system (F-measure +4.1%, p=0.002). It also reduced of number of sentences to be processed by 44.9% (p<0.001), which corresponds to a processing time reduction of 50% (p=0.005). The rule-based multi-pass sieve framework can be used effectively in categorizing texts extracted from PDF documents. Text classification is an important prerequisite step to leverage information extraction from PDF documents. Copyright © 2016 Elsevier Inc. All rights reserved.

Classification of Traffic Related Short Texts to Analyse Road Problems in Urban Areas

NASA Astrophysics Data System (ADS)

Saldana-Perez, A. M. M.; Moreno-Ibarra, M.; Tores-Ruiz, M.

2017-09-01

The Volunteer Geographic Information (VGI) can be used to understand the urban dynamics. In the classification of traffic related short texts to analyze road problems in urban areas, a VGI data analysis is done over a social media's publications, in order to classify traffic events at big cities that modify the movement of vehicles and people through the roads, such as car accidents, traffic and closures. The classification of traffic events described in short texts is done by applying a supervised machine learning algorithm. In the approach users are considered as sensors which describe their surroundings and provide their geographic position at the social network. The posts are treated by a text mining process and classified into five groups. Finally, the classified events are grouped in a data corpus and geo-visualized in the study area, to detect the places with more vehicular problems.

Exploring supervised and unsupervised methods to detect topics in biomedical text

PubMed Central

Lee, Minsuk; Wang, Weiqing; Yu, Hong

2006-01-01

Background Topic detection is a task that automatically identifies topics (e.g., "biochemistry" and "protein structure") in scientific articles based on information content. Topic detection will benefit many other natural language processing tasks including information retrieval, text summarization and question answering; and is a necessary step towards the building of an information system that provides an efficient way for biologists to seek information from an ocean of literature. Results We have explored the methods of Topic Spotting, a task of text categorization that applies the supervised machine-learning technique naïve Bayes to assign automatically a document into one or more predefined topics; and Topic Clustering, which apply unsupervised hierarchical clustering algorithms to aggregate documents into clusters such that each cluster represents a topic. We have applied our methods to detect topics of more than fifteen thousand of articles that represent over sixteen thousand entries in the Online Mendelian Inheritance in Man (OMIM) database. We have explored bag of words as the features. Additionally, we have explored semantic features; namely, the Medical Subject Headings (MeSH) that are assigned to the MEDLINE records, and the Unified Medical Language System (UMLS) semantic types that correspond to the MeSH terms, in addition to bag of words, to facilitate the tasks of topic detection. Our results indicate that incorporating the MeSH terms and the UMLS semantic types as additional features enhances the performance of topic detection and the naïve Bayes has the highest accuracy, 66.4%, for predicting the topic of an OMIM article as one of the total twenty-five topics. Conclusion Our results indicate that the supervised topic spotting methods outperformed the unsupervised topic clustering; on the other hand, the unsupervised topic clustering methods have the advantages of being robust and applicable in real world settings. PMID:16539745

Drug-related webpages classification based on multi-modal local decision fusion

NASA Astrophysics Data System (ADS)

Hu, Ruiguang; Su, Xiaojing; Liu, Yanxin

2018-03-01

In this paper, multi-modal local decision fusion is used for drug-related webpages classification. First, meaningful text are extracted through HTML parsing, and effective images are chosen by the FOCARSS algorithm. Second, six SVM classifiers are trained for six kinds of drug-taking instruments, which are represented by PHOG. One SVM classifier is trained for the cannabis, which is represented by the mid-feature of BOW model. For each instance in a webpage, seven SVMs give seven labels for its image, and other seven labels are given by searching the names of drug-taking instruments and cannabis in its related text. Concatenating seven labels of image and seven labels of text, the representation of those instances in webpages are generated. Last, Multi-Instance Learning is used to classify those drugrelated webpages. Experimental results demonstrate that the classification accuracy of multi-instance learning with multi-modal local decision fusion is much higher than those of single-modal classification.

Computer Supported Indexing: A History and Evaluation of NASA's MAI System. Supplement 24

NASA Technical Reports Server (NTRS)

Silvester, June P.

1997-01-01

Computer supported indexing systems may be categorized in several ways. One classification scheme refers to them as statistical, syntactic, semantic or knowledge-based. While a system may emphasize one of these aspects, most systems actually combine two or more of these mechanisms to maximize system efficiency. Statistical systems can be based on counts of words or word stems, statistical association, and correlation techniques that assign weights to word locations or provide lexical disambiguation, calculations regarding the likelihood of word co-occurrences, clustering of word stems and transformations, or any other computational method used to identify pertinent terms. If words are counted, the ones of median frequency become candidate index terms. Syntactical systems stress grammar and identify parts of speech. Concepts found in designated grammatical combinations, such as noun phrases, generate the suggested terms. Semantic systems are concerned with the context sensitivity of words in text. The primary goal of this type of indexing is to identify without regard to syntax the subject matter and the context-bearing words in the text being indexed. Knowledge-based systems provide a conceptual network that goes past thesaurus or equivalent relationships to knowing (e.g., in the National Library of Medicine (NLM) system) that because the tibia is part of the leg, a document relating to injuries to the tibia should he indexed to LEG INJURIES, not the broader MeSH term INJURIES, or knowing that the term FEMALE should automatically be added when the term PREGNANCY is assigned, and also that the indexer should be prompted to add either HUMAN or ANIMAL. Another way of categorizing indexing systems is to identify them as producing either assigned- or derived-term indexes.

Online EEG Classification of Covert Speech for Brain-Computer Interfacing.

PubMed

Sereshkeh, Alborz Rezazadeh; Trott, Robert; Bricout, Aurélien; Chau, Tom

2017-12-01

Brain-computer interfaces (BCIs) for communication can be nonintuitive, often requiring the performance of hand motor imagery or some other conversation-irrelevant task. In this paper, electroencephalography (EEG) was used to develop two intuitive online BCIs based solely on covert speech. The goal of the first BCI was to differentiate between 10[Formula: see text]s of mental repetitions of the word "no" and an equivalent duration of unconstrained rest. The second BCI was designed to discern between 10[Formula: see text]s each of covert repetition of the words "yes" and "no". Twelve participants used these two BCIs to answer yes or no questions. Each participant completed four sessions, comprising two offline training sessions and two online sessions, one for testing each of the BCIs. With a support vector machine and a combination of spectral and time-frequency features, an average accuracy of [Formula: see text] was reached across participants in the online classification of no versus rest, with 10 out of 12 participants surpassing the chance level (60.0% for [Formula: see text]). The online classification of yes versus no yielded an average accuracy of [Formula: see text], with eight participants exceeding the chance level. Task-specific changes in EEG beta and gamma power in language-related brain areas tended to provide discriminatory information. To our knowledge, this is the first report of online EEG classification of covert speech. Our findings support further study of covert speech as a BCI activation task, potentially leading to the development of more intuitive BCIs for communication.

Symbolic rule-based classification of lung cancer stages from free-text pathology reports.

PubMed

Nguyen, Anthony N; Lawley, Michael J; Hansen, David P; Bowman, Rayleen V; Clarke, Belinda E; Duhig, Edwina E; Colquist, Shoni

2010-01-01

To classify automatically lung tumor-node-metastases (TNM) cancer stages from free-text pathology reports using symbolic rule-based classification. By exploiting report substructure and the symbolic manipulation of systematized nomenclature of medicine-clinical terms (SNOMED CT) concepts in reports, statements in free text can be evaluated for relevance against factors relating to the staging guidelines. Post-coordinated SNOMED CT expressions based on templates were defined and populated by concepts in reports, and tested for subsumption by staging factors. The subsumption results were used to build logic according to the staging guidelines to calculate the TNM stage. The accuracy measure and confusion matrices were used to evaluate the TNM stages classified by the symbolic rule-based system. The system was evaluated against a database of multidisciplinary team staging decisions and a machine learning-based text classification system using support vector machines. Overall accuracy on a corpus of pathology reports for 718 lung cancer patients against a database of pathological TNM staging decisions were 72%, 78%, and 94% for T, N, and M staging, respectively. The system's performance was also comparable to support vector machine classification approaches. A system to classify lung TNM stages from free-text pathology reports was developed, and it was verified that the symbolic rule-based approach using SNOMED CT can be used for the extraction of key lung cancer characteristics from free-text reports. Future work will investigate the applicability of using the proposed methodology for extracting other cancer characteristics and types.

The Labelling Approach to Deviance.

ERIC Educational Resources Information Center

Rains, Prudence M.; Kitsuse, John L.; Duster, Troy; Freidson, Eliot

2003-01-01

This reprint of one chapter from the 1975 text, "Issues in the Classification of Children" by Nicholas Hobbs and others, addresses the theoretical, methodological, and empirical issues involved in the "labeling" approach to the sociology of deviance. It examines the social process of classification, the use of classification in social agencies,…

Health Instruction Packages: Drug Dosage, Classification, and Mixing.

ERIC Educational Resources Information Center

Bracchi, Dorothy P.; And Others

Text, illustrations, and exercises are utilized in a set of seven learning modules to instruct nursing students in the fundamentals of drug classification, dosage, and mixing. The first module, by Dorothy Bracchi, teaches the student to identify six classifications of medication often administered to orthopedic patients: anti-neurospasmolytic…

Sentiment analysis of feature ranking methods for classification accuracy

NASA Astrophysics Data System (ADS)

Joseph, Shashank; Mugauri, Calvin; Sumathy, S.

2017-11-01

Text pre-processing and feature selection are important and critical steps in text mining. Text pre-processing of large volumes of datasets is a difficult task as unstructured raw data is converted into structured format. Traditional methods of processing and weighing took much time and were less accurate. To overcome this challenge, feature ranking techniques have been devised. A feature set from text preprocessing is fed as input for feature selection. Feature selection helps improve text classification accuracy. Of the three feature selection categories available, the filter category will be the focus. Five feature ranking methods namely: document frequency, standard deviation information gain, CHI-SQUARE, and weighted-log likelihood -ratio is analyzed.

Chi-square-based scoring function for categorization of MEDLINE citations.

PubMed

Kastrin, A; Peterlin, B; Hristovski, D

2010-01-01

Text categorization has been used in biomedical informatics for identifying documents containing relevant topics of interest. We developed a simple method that uses a chi-square-based scoring function to determine the likelihood of MEDLINE citations containing genetic relevant topic. Our procedure requires construction of a genetic and a nongenetic domain document corpus. We used MeSH descriptors assigned to MEDLINE citations for this categorization task. We compared frequencies of MeSH descriptors between two corpora applying chi-square test. A MeSH descriptor was considered to be a positive indicator if its relative observed frequency in the genetic domain corpus was greater than its relative observed frequency in the nongenetic domain corpus. The output of the proposed method is a list of scores for all the citations, with the highest score given to those citations containing MeSH descriptors typical for the genetic domain. Validation was done on a set of 734 manually annotated MEDLINE citations. It achieved predictive accuracy of 0.87 with 0.69 recall and 0.64 precision. We evaluated the method by comparing it to three machine-learning algorithms (support vector machines, decision trees, naïve Bayes). Although the differences were not statistically significantly different, results showed that our chi-square scoring performs as good as compared machine-learning algorithms. We suggest that the chi-square scoring is an effective solution to help categorize MEDLINE citations. The algorithm is implemented in the BITOLA literature-based discovery support system as a preprocessor for gene symbol disambiguation process.

Ranking the whole MEDLINE database according to a large training set using text indexing.

PubMed

Suomela, Brian P; Andrade, Miguel A

2005-03-24

The MEDLINE database contains over 12 million references to scientific literature, with about 3/4 of recent articles including an abstract of the publication. Retrieval of entries using queries with keywords is useful for human users that need to obtain small selections. However, particular analyses of the literature or database developments may need the complete ranking of all the references in the MEDLINE database as to their relevance to a topic of interest. This report describes a method that does this ranking using the differences in word content between MEDLINE entries related to a topic and the whole of MEDLINE, in a computational time appropriate for an article search query engine. We tested the capabilities of our system to retrieve MEDLINE references which are relevant to the subject of stem cells. We took advantage of the existing annotation of references with terms from the MeSH hierarchical vocabulary (Medical Subject Headings, developed at the National Library of Medicine). A training set of 81,416 references was constructed by selecting entries annotated with the MeSH term stem cells or some child in its sub tree. Frequencies of all nouns, verbs, and adjectives in the training set were computed and the ratios of word frequencies in the training set to those in the entire MEDLINE were used to score references. Self-consistency of the algorithm, benchmarked with a test set containing the training set and an equal number of references randomly selected from MEDLINE was better using nouns (79%) than adjectives (73%) or verbs (70%). The evaluation of the system with 6,923 references not used for training, containing 204 articles relevant to stem cells according to a human expert, indicated a recall of 65% for a precision of 65%. This strategy appears to be useful for predicting the relevance of MEDLINE references to a given concept. The method is simple and can be used with any user-defined training set. Choice of the part of speech of the words used for classification has important effects on performance. Lists of words, scripts, and additional information are available from the web address http://www.ogic.ca/projects/ks2004/.

Semantic Classification of Diseases in Discharge Summaries Using a Context-aware Rule-based Classifier

PubMed Central

Solt, Illés; Tikk, Domonkos; Gál, Viktor; Kardkovács, Zsolt T.

2009-01-01

Objective Automated and disease-specific classification of textual clinical discharge summaries is of great importance in human life science, as it helps physicians to make medical studies by providing statistically relevant data for analysis. This can be further facilitated if, at the labeling of discharge summaries, semantic labels are also extracted from text, such as whether a given disease is present, absent, questionable in a patient, or is unmentioned in the document. The authors present a classification technique that successfully solves the semantic classification task. Design The authors introduce a context-aware rule-based semantic classification technique for use on clinical discharge summaries. The classification is performed in subsequent steps. First, some misleading parts are removed from the text; then the text is partitioned into positive, negative, and uncertain context segments, then a sequence of binary classifiers is applied to assign the appropriate semantic labels. Measurement For evaluation the authors used the documents of the i2b2 Obesity Challenge and adopted its evaluation measures: F1-macro and F1-micro for measurements. Results On the two subtasks of the Obesity Challenge (textual and intuitive classification) the system performed very well, and achieved a F1-macro = 0.80 for the textual and F1-macro = 0.67 for the intuitive tasks, and obtained second place at the textual and first place at the intuitive subtasks of the challenge. Conclusions The authors show in the paper that a simple rule-based classifier can tackle the semantic classification task more successfully than machine learning techniques, if the training data are limited and some semantic labels are very sparse. PMID:19390101

Cost of ventral hernia repair using biologic or synthetic mesh.

PubMed

Totten, Crystal F; Davenport, Daniel L; Ward, Nicholas D; Roth, J Scott

2016-06-15

Patients undergoing ventral hernia repair (VHR) with biologic mesh (BioM) have higher hospital costs compared with synthetic mesh (SynM). This study compares 90-d pre- and post-VHR hospital costs (180-d) among BioM and SynM based on infection risk. This retrospective National Surgical Quality Improvement Program study matched patient perioperative risk with resource utilization cost for a consecutive series of VHR repairs. Patient infection risks, clinical and financial outcomes were compared in unmatched SynM (n = 303) and BioM (n = 72) groups. Propensity scores were used to match 35 SynM and BioM pairs of cases with similar infection risk for outcomes analysis. BioM patients in the unmatched group were older with higher American Society of Anesthesiologists (ASA) and wound classification, and they more frequently underwent open repairs for recurrent hernias. Wound surgical site infections were more frequent in unmatched BioM patients (P = 0.001) as were 180-d costs ($43.8k versus $14.0k, P < 0.001). Propensity matching resulted in 31 clean cases. In these low-risk patients, wound occurrences and readmissions were identical, but 180-d costs remained higher ($31.8k versus $15.5k, P < 0.001). There were no differences in hospital 180-d diagnostic, emergency room, intensive care unit, floor, pharmacy, or therapeutic costs. However, 180-d operating room services and supply costs were higher in the BioM group ($21.1k versus $7.1k, P < 0.001). BioM is used more commonly in hernia repairs involving higher wound class and ASA scores and recurrent hernias. Clinical outcomes after low-risk VHRs are similar; SynM utilization in low-risk hernia repairs was more cost-effective. Published by Elsevier Inc.

The NLM Indexing Initiative's Medical Text Indexer.

PubMed

Aronson, Alan R; Mork, James G; Gay, Clifford W; Humphrey, Susanne M; Rogers, Willie J

2004-01-01

The Medical Text Indexer (MTI) is a program for producing MeSH indexing recommendations. It is the major product of NLM's Indexing Initiative and has been used in both semi-automated and fully automated indexing environments at the Library since mid 2002. We report here on an experiment conducted with MEDLINE indexers to evaluate MTI's performance and to generate ideas for its improvement as a tool for user-assisted indexing. We also discuss some filtering techniques developed to improve MTI's accuracy for use primarily in automatically producing the indexing for several abstracts collections.

Assessment of adhesion formation to intra-abdominal polypropylene mesh and polytetrafluoroethylene mesh.

PubMed

Matthews, Brent D; Pratt, Broc L; Pollinger, Harrison S; Backus, Charles L; Kercher, Kent W; Sing, R F; Heniford, B Todd

2003-10-01

The development of intra-abdominal adhesions, bowel obstruction, and enterocutaneous fistulas are potentially severe complications related to the intraperitoneal placement of prosthetic biomaterials. The purpose of this study was to determine the natural history of adhesion formation to polypropylene mesh and two types of polytetrafluoroethylene (ePTFE) mesh when placed intraperitoneally in a rabbit model that simulates laparoscopic ventral hernia repair. Thirty New Zealand white rabbits were used for this study. A 10-cm midline incision was performed for intra-abdominal access and a 2 cm x 2 cm piece of mesh (n = 60) was sewn to an intact peritoneum on each side of the midline. Two types of ePTFE mesh (Dual Mesh and modified Dual Mesh, W.L. Gore & Assoc., Flagstaff, AZ) and polypropylene mesh were compared. The rate of adhesion formation was evaluated by direct visualization using microlaparoscopy (2-mm endoscope/trocar) at 7 days, 3 weeks, 9 weeks, and 16 weeks after mesh implantation. Adhesions to the prosthetic mesh were scored for extent (%) using the Modified Diamond Scale (0 = 0%, 1 50%). At necropsy the mesh was excised en bloc with the anterior abdominal wall for histological evaluation of mesothelial layer growth. The mean adhesion score for the polypropylene mesh was significantly greater (P < 0.05) than Dual Mesh at 9 weeks and 16 weeks and modified Dual Mesh at 7 days, 9 weeks, and 16 weeks. Fifty-five percent (n = 11) of the polypropylene mesh had adhesions to small intestine or omentum at necropsy compared to 30% (n = 6) of the Dual Mesh and 20% (n = 4) of the modified Dual Mesh. There was a significantly greater percentage (P < 0.003) of ePTFE mesh mesothelialized at explant (modified Dual Mesh 44.2%; Dual Mesh 55.8%) compared to the polypropylene mesh (12.9%). Serial microlaparoscopic evaluation of intraperitoneally implanted polypropylene mesh and ePTFE mesh in a rabbit model revealed a progression of adhesions to polypropylene mesh over a 16 week period. The pore size of mesh is critical in the development and maintenance of abdominal adhesions and tissue ingrowth. The macroporous polypropylene mesh promoted adhesion formation, while the microporous nature of the visceral side of the ePTFE served as a barrier to adhesions.

Which drugs are risk factors for the development of gastroesophageal reflux disease?

PubMed

Mungan, Zeynel; Pınarbaşı Şimşek, Binnur

2017-12-01

Gastroesophageal reflux disease (GERD), which is common in many communities, is associated with structural factors, eating habits, and the use of certain drugs. The use of such drugs can lead to the emergence of GERD and can also exacerbate existing reflux symptoms. These drugs can contribute to GERD by directly causing mucosal damage, by reducing lower esophageal sphincter pressure (LESP), or by affecting esophagogastric motility. In this article, we report our investigation of the relationships between GERD and medications within the scope of the "Turkish GERD Consensus Group." For the medication groups for which sufficient data were obtained (Figure 1), a systematic literature review in English was conducted using the keywords "gastroesophageal reflux" [MeSH Terms] and "anti-inflammatory agents, non-steroidal" [MeSH Terms], "gastroesophageal reflux" [MeSH Terms] and "acetylsalicylic acid" [MeSH Terms], "gastroesophageal reflux" [All Fields] and "estrogenic agents" [All Fields], "gastroesophageal reflux" [All Fields] and "progesterones" [All Fields], "gastroesophageal reflux" [All Fields] and "hormone replacement therapy" [All Fields], "gastroesophageal reflux" [MeSH Terms] and "diphosphonates" [MeSH Terms] OR "diphosphonates" [All Fields], "calcium channel blockers" [MeSH Terms] and "gastroesophageal reflux" [MeSH Terms], "gastroesophageal reflux" [MeSH Terms] and "nitrates" [MeSH Terms], "gastroesophageal reflux" [MeSH Terms] and "antidepressive agents" [MeSH Terms], "gastroesophageal reflux" [MeSH Terms] and "benzodiazepines" [MeSH Terms] and "hypnotic drugs" [MeSH Terms], "gastroesophageal reflux" [MeSH Terms] and "cholinergic antagonists" [MeSH Terms], "gastroesophageal reflux" [MeSH Terms] and "theophylline" [MeSH Terms], and "gastroesophageal reflux [MeSH Terms] AND "anti-asthmatic agents" [MeSH Terms]. The studies were analyzed and the results are presented here.

Relevance popularity: A term event model based feature selection scheme for text classification.

PubMed

Feng, Guozhong; An, Baiguo; Yang, Fengqin; Wang, Han; Zhang, Libiao

2017-01-01

Feature selection is a practical approach for improving the performance of text classification methods by optimizing the feature subsets input to classifiers. In traditional feature selection methods such as information gain and chi-square, the number of documents that contain a particular term (i.e. the document frequency) is often used. However, the frequency of a given term appearing in each document has not been fully investigated, even though it is a promising feature to produce accurate classifications. In this paper, we propose a new feature selection scheme based on a term event Multinomial naive Bayes probabilistic model. According to the model assumptions, the matching score function, which is based on the prediction probability ratio, can be factorized. Finally, we derive a feature selection measurement for each term after replacing inner parameters by their estimators. On a benchmark English text datasets (20 Newsgroups) and a Chinese text dataset (MPH-20), our numerical experiment results obtained from using two widely used text classifiers (naive Bayes and support vector machine) demonstrate that our method outperformed the representative feature selection methods.

Conceptual-driven classification for coding advise in health insurance reimbursement.

PubMed

Li, Sheng-Tun; Chen, Chih-Chuan; Huang, Fernando

2011-01-01

With the non-stop increases in medical treatment fees, the economic survival of a hospital in Taiwan relies on the reimbursements received from the Bureau of National Health Insurance, which in turn depend on the accuracy and completeness of the content of the discharge summaries as well as the correctness of their International Classification of Diseases (ICD) codes. The purpose of this research is to enforce the entire disease classification framework by supporting disease classification specialists in the coding process. This study developed an ICD code advisory system (ICD-AS) that performed knowledge discovery from discharge summaries and suggested ICD codes. Natural language processing and information retrieval techniques based on Zipf's Law were applied to process the content of discharge summaries, and fuzzy formal concept analysis was used to analyze and represent the relationships between the medical terms identified by MeSH. In addition, a certainty factor used as reference during the coding process was calculated to account for uncertainty and strengthen the credibility of the outcome. Two sets of 360 and 2579 textual discharge summaries of patients suffering from cerebrovascular disease was processed to build up ICD-AS and to evaluate the prediction performance. A number of experiments were conducted to investigate the impact of system parameters on accuracy and compare the proposed model to traditional classification techniques including linear-kernel support vector machines. The comparison results showed that the proposed system achieves the better overall performance in terms of several measures. In addition, some useful implication rules were obtained, which improve comprehension of the field of cerebrovascular disease and give insights to the relationships between relevant medical terms. Our system contributes valuable guidance to disease classification specialists in the process of coding discharge summaries, which consequently brings benefits in aspects of patient, hospital, and healthcare system. Copyright © 2010 Elsevier B.V. All rights reserved.

Self-organizing ontology of biochemically relevant small molecules

PubMed Central

2012-01-01

Background The advent of high-throughput experimentation in biochemistry has led to the generation of vast amounts of chemical data, necessitating the development of novel analysis, characterization, and cataloguing techniques and tools. Recently, a movement to publically release such data has advanced biochemical structure-activity relationship research, while providing new challenges, the biggest being the curation, annotation, and classification of this information to facilitate useful biochemical pattern analysis. Unfortunately, the human resources currently employed by the organizations supporting these efforts (e.g. ChEBI) are expanding linearly, while new useful scientific information is being released in a seemingly exponential fashion. Compounding this, currently existing chemical classification and annotation systems are not amenable to automated classification, formal and transparent chemical class definition axiomatization, facile class redefinition, or novel class integration, thus further limiting chemical ontology growth by necessitating human involvement in curation. Clearly, there is a need for the automation of this process, especially for novel chemical entities of biological interest. Results To address this, we present a formal framework based on Semantic Web technologies for the automatic design of chemical ontology which can be used for automated classification of novel entities. We demonstrate the automatic self-assembly of a structure-based chemical ontology based on 60 MeSH and 40 ChEBI chemical classes. This ontology is then used to classify 200 compounds with an accuracy of 92.7%. We extend these structure-based classes with molecular feature information and demonstrate the utility of our framework for classification of functionally relevant chemicals. Finally, we discuss an iterative approach that we envision for future biochemical ontology development. Conclusions We conclude that the proposed methodology can ease the burden of chemical data annotators and dramatically increase their productivity. We anticipate that the use of formal logic in our proposed framework will make chemical classification criteria more transparent to humans and machines alike and will thus facilitate predictive and integrative bioactivity model development. PMID:22221313

Using statistical text classification to identify health information technology incidents

PubMed Central

Chai, Kevin E K; Anthony, Stephen; Coiera, Enrico; Magrabi, Farah

2013-01-01

Objective To examine the feasibility of using statistical text classification to automatically identify health information technology (HIT) incidents in the USA Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database. Design We used a subset of 570 272 incidents including 1534 HIT incidents reported to MAUDE between 1 January 2008 and 1 July 2010. Text classifiers using regularized logistic regression were evaluated with both ‘balanced’ (50% HIT) and ‘stratified’ (0.297% HIT) datasets for training, validation, and testing. Dataset preparation, feature extraction, feature selection, cross-validation, classification, performance evaluation, and error analysis were performed iteratively to further improve the classifiers. Feature-selection techniques such as removing short words and stop words, stemming, lemmatization, and principal component analysis were examined. Measurements κ statistic, F1 score, precision and recall. Results Classification performance was similar on both the stratified (0.954 F1 score) and balanced (0.995 F1 score) datasets. Stemming was the most effective technique, reducing the feature set size to 79% while maintaining comparable performance. Training with balanced datasets improved recall (0.989) but reduced precision (0.165). Conclusions Statistical text classification appears to be a feasible method for identifying HIT reports within large databases of incidents. Automated identification should enable more HIT problems to be detected, analyzed, and addressed in a timely manner. Semi-supervised learning may be necessary when applying machine learning to big data analysis of patient safety incidents and requires further investigation. PMID:23666777

The impact of OCR accuracy on automated cancer classification of pathology reports.

PubMed

Zuccon, Guido; Nguyen, Anthony N; Bergheim, Anton; Wickman, Sandra; Grayson, Narelle

2012-01-01

To evaluate the effects of Optical Character Recognition (OCR) on the automatic cancer classification of pathology reports. Scanned images of pathology reports were converted to electronic free-text using a commercial OCR system. A state-of-the-art cancer classification system, the Medical Text Extraction (MEDTEX) system, was used to automatically classify the OCR reports. Classifications produced by MEDTEX on the OCR versions of the reports were compared with the classification from a human amended version of the OCR reports. The employed OCR system was found to recognise scanned pathology reports with up to 99.12% character accuracy and up to 98.95% word accuracy. Errors in the OCR processing were found to minimally impact on the automatic classification of scanned pathology reports into notifiable groups. However, the impact of OCR errors is not negligible when considering the extraction of cancer notification items, such as primary site, histological type, etc. The automatic cancer classification system used in this work, MEDTEX, has proven to be robust to errors produced by the acquisition of freetext pathology reports from scanned images through OCR software. However, issues emerge when considering the extraction of cancer notification items.

Performance Evaluation of Frequency Transform Based Block Classification of Compound Image Segmentation Techniques

NASA Astrophysics Data System (ADS)

Selwyn, Ebenezer Juliet; Florinabel, D. Jemi

2018-04-01

Compound image segmentation plays a vital role in the compression of computer screen images. Computer screen images are images which are mixed with textual, graphical, or pictorial contents. In this paper, we present a comparison of two transform based block classification of compound images based on metrics like speed of classification, precision and recall rate. Block based classification approaches normally divide the compound images into fixed size blocks of non-overlapping in nature. Then frequency transform like Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) are applied over each block. Mean and standard deviation are computed for each 8 × 8 block and are used as features set to classify the compound images into text/graphics and picture/background block. The classification accuracy of block classification based segmentation techniques are measured by evaluation metrics like precision and recall rate. Compound images of smooth background and complex background images containing text of varying size, colour and orientation are considered for testing. Experimental evidence shows that the DWT based segmentation provides significant improvement in recall rate and precision rate approximately 2.3% than DCT based segmentation with an increase in block classification time for both smooth and complex background images.

Sur la classification des adverbes en -ment (On the Classification of -ment Adverbs)

ERIC Educational Resources Information Center

Mordrup, Ole

1976-01-01

Presents a classification of French "-ment" adverbs based on syntactical criteria. The major divisions, consisting of "sentence adverbs" and "adverbs of manner," are further sub-divided into functional sub-groups. (Text is in French.) Available from: Akademisk Forlag, St. Kannikestraede 6-8, DK-1169 Copenhague K Danemark. (AM)

48 CFR 19.303 - Determining North American Industry Classification System (NAICS) codes and size standards.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Industry Classification System (NAICS) codes and size standards. 19.303 Section 19.303 Federal Acquisition... of Small Business Status for Small Business Programs 19.303 Determining North American Industry... user, the added text is set forth as follows: 19.303 Determining North American Industry Classification...

Combined in vivo and ex vivo analysis of mesh mechanics in a porcine hernia model.

PubMed

Kahan, Lindsey G; Lake, Spencer P; McAllister, Jared M; Tan, Wen Hui; Yu, Jennifer; Thompson, Dominic; Brunt, L Michael; Blatnik, Jeffrey A

2018-02-01

Hernia meshes exhibit variability in mechanical properties, and their mechanical match to tissue has not been comprehensively studied. We used an innovative imaging model of in vivo strain tracking and ex vivo mechanical analysis to assess effects of mesh properties on repaired abdominal walls in a porcine model. We hypothesized that meshes with dissimilar mechanical properties compared to native tissue would alter abdominal wall mechanics more than better-matched meshes. Seven mini-pigs underwent ventral hernia creation and subsequent open repair with one of two heavyweight polypropylene meshes. Following mesh implantation with attached radio-opaque beads, fluoroscopic images were taken at insufflation pressures from 5 to 30 mmHg on postoperative days 0, 7, and 28. At 28 days, animals were euthanized and ex vivo mechanical testing performed on full-thickness samples across repaired abdominal walls. Testing was conducted on 13 mini-pig controls, and on meshes separately. Stiffness and anisotropy (the ratio of stiffness in the transverse versus craniocaudal directions) were assessed. 3D reconstructions of repaired abdominal walls showed stretch patterns. As pressure increased, both meshes expanded, with no differences between groups. Over time, meshes contracted 17.65% (Mesh A) and 0.12% (Mesh B; p = 0.06). Mesh mechanics showed that Mesh A deviated from anisotropic native tissue more than Mesh B. Compared to native tissue, Mesh A was stiffer both transversely and craniocaudally. Explanted repaired abdominal walls of both treatment groups were stiffer than native tissue. Repaired tissue became less anisotropic over time, as mesh properties prevailed over native abdominal wall properties. This technique assessed 3D stretch at the mesh level in vivo in a porcine model. While the abdominal wall expanded, mesh-ingrown areas contracted, potentially indicating stresses at mesh edges. Ex vivo mechanics demonstrate that repaired tissue adopts mesh properties, suggesting that a better-matched mesh could reduce changes to abdominal wall mechanics.

Mesh fixation in laparoscopic incisional hernia repair: glue fixation provides attachment strength similar to absorbable tacks but differs substantially in different meshes.

PubMed

Rieder, Erwin; Stoiber, Martin; Scheikl, Verena; Poglitsch, Marcus; Dal Borgo, Andrea; Prager, Gerhard; Schima, Heinrich

2011-01-01

Laparoscopic ventral hernia repair has gained popularity among minimally invasive surgeons. However, mesh fixation remains a matter of discussion. This study was designed to compare noninvasive fibrin-glue attachment with tack fixation of meshes developed primarily for intra-abdominal use. It was hypothesized that particular mesh structures would substantially influence detachment force. For initial evaluation, specimens of laminated polypropylene/polydioxanone meshes were anchored to porcine abdominal walls by either helical titanium tacks or absorbable tacks in vitro. A universal tensile-testing machine was used to measure tangential detachment forces (TF). For subsequent experiments of glue fixation, polypropylene/polydioxanone mesh and 4 additional meshes with diverse particular mesh structure, ie, polyvinylidene fluoride/polypropylene mesh, a titanium-coated polypropylene mesh, a polyester mesh bonded with a resorbable collagen, and a macroporous condensed PTFE mesh were evaluated. TF tests revealed that fibrin-glue attachment was not substantially different from that achieved with absorbable tacks (median TF 7.8 Newton [N], range 1.3 to 15.8 N), but only when certain open porous meshes (polyvinylidene fluoride/polypropylene mesh: median 6.2 N, range 3.4 to 10.3 N; titanium-coated polypropylene mesh: median 5.2 N, range 2.1 to 11.7 N) were used. Meshes coated by an anti-adhesive barrier (polypropylene/polydioxanone mesh: median 3.1 N, range 1.7 to 5.8 N; polyester mesh bonded with a resorbable collagen: median 1.3 N, range 0.5 to 1.9 N), or the condensed PTFE mesh (median 3.1 N, range 2.1 to 7.0 N) provided a significantly lower TF (p < 0.01). Fibrin glue appears to be an appealing noninvasive option for mesh fixation in laparoscopic ventral hernia repair, but only if appropriate meshes are used. Glue can also serve as an adjunct to mechanical fixation to reduce the number of invasive tacks. Copyright © 2010 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Ensemble of classifiers for ontology enrichment

NASA Astrophysics Data System (ADS)

Semenova, A. V.; Kureichik, V. M.

2018-05-01

A classifier is a basis of ontology learning systems. Classification of text documents is used in many applications, such as information retrieval, information extraction, definition of spam. A new ensemble of classifiers based on SVM (a method of support vectors), LSTM (neural network) and word embedding are suggested. An experiment was conducted on open data, which allows us to conclude that the proposed classification method is promising. The implementation of the proposed classifier is performed in the Matlab using the functions of the Text Analytics Toolbox. The principal difference between the proposed ensembles of classifiers is the high quality of classification of data at acceptable time costs.

Method and system for mesh network embedded devices

NASA Technical Reports Server (NTRS)

Wang, Ray (Inventor)

2009-01-01

A method and system for managing mesh network devices. A mesh network device with integrated features creates an N-way mesh network with a full mesh network topology or a partial mesh network topology.

Convergence study of global meshing on enamel-cement-bracket finite element model

NASA Astrophysics Data System (ADS)

Samshuri, S. F.; Daud, R.; Rojan, M. A.; Basaruddin, K. S.; Abdullah, A. B.; Ariffin, A. K.

2017-09-01

This paper presents on meshing convergence analysis of finite element (FE) model to simulate enamel-cement-bracket fracture. Three different materials used in this study involving interface fracture are concerned. Complex behavior ofinterface fracture due to stress concentration is the reason to have a well-constructed meshing strategy. In FE analysis, meshing size is a critical factor that influenced the accuracy and computational time of analysis. The convergence study meshing scheme involving critical area (CA) and non-critical area (NCA) to ensure an optimum meshing sizes are acquired for this FE model. For NCA meshing, the area of interest are at the back of enamel, bracket ligature groove and bracket wing. For CA meshing, area of interest are enamel area close to cement layer, the cement layer and bracket base. The value of constant NCA meshing tested are meshing size 1 and 0.4. The value constant CA meshing tested are 0.4 and 0.1. Manipulative variables are randomly selected and must abide the rule of NCA must be higher than CA. This study employed first principle stresses due to brittle failure nature of the materials used. Best meshing size are selected according to convergence error analysis. Results show that, constant CA are more stable compare to constant NCA meshing. Then, 0.05 constant CA meshing are tested to test the accuracy of smaller meshing. However, unpromising result obtained as the errors are increasing. Thus, constant CA 0.1 with NCA mesh of 0.15 until 0.3 are the most stable meshing as the error in this region are lowest. Convergence test was conducted on three selected coarse, medium and fine meshes at the range of NCA mesh of 0.15 until 3 and CA mesh area stay constant at 0.1. The result shows that, at coarse mesh 0.3, the error are 0.0003% compare to 3% acceptable error. Hence, the global meshing are converge as the meshing size at CA 0.1 and NCA 0.15 for this model.

Method and apparatus for connecting finite element meshes and performing simulations therewith

DOEpatents

Dohrmann, Clark R.; Key, Samuel W.; Heinstein, Martin W.

2003-05-06

The present invention provides a method of connecting dissimilar finite element meshes. A first mesh, designated the master mesh, and a second mesh, designated the slave mesh, each have interface surfaces proximal the other. Each interface surface has a corresponding interface mesh comprising a plurality of interface nodes. Each slave interface node is assigned new coordinates locating the interface node on the interface surface of the master mesh. The slave interface surface is further redefined to be the projection of the slave interface mesh onto the master interface surface.

A methodology for quadrilateral finite element mesh coarsening

DOE PAGES

Staten, Matthew L.; Benzley, Steven; Scott, Michael

2008-03-27

High fidelity finite element modeling of continuum mechanics problems often requires using all quadrilateral or all hexahedral meshes. The efficiency of such models is often dependent upon the ability to adapt a mesh to the physics of the phenomena. Adapting a mesh requires the ability to both refine and/or coarsen the mesh. The algorithms available to refine and coarsen triangular and tetrahedral meshes are very robust and efficient. However, the ability to locally and conformally refine or coarsen all quadrilateral and all hexahedral meshes presents many difficulties. Some research has been done on localized conformal refinement of quadrilateral and hexahedralmore » meshes. However, little work has been done on localized conformal coarsening of quadrilateral and hexahedral meshes. A general method which provides both localized conformal coarsening and refinement for quadrilateral meshes is presented in this paper. This method is based on restructuring the mesh with simplex manipulations to the dual of the mesh. Finally, this method appears to be extensible to hexahedral meshes in three dimensions.« less

Adaptive Skin Meshes Coarsening for Biomolecular Simulation

PubMed Central

Shi, Xinwei; Koehl, Patrice

2011-01-01

In this paper, we present efficient algorithms for generating hierarchical molecular skin meshes with decreasing size and guaranteed quality. Our algorithms generate a sequence of coarse meshes for both the surfaces and the bounded volumes. Each coarser surface mesh is adaptive to the surface curvature and maintains the topology of the skin surface with guaranteed mesh quality. The corresponding tetrahedral mesh is conforming to the interface surface mesh and contains high quality tetrahedral that decompose both the interior of the molecule and the surrounding region (enclosed in a sphere). Our hierarchical tetrahedral meshes have a number of advantages that will facilitate fast and accurate multigrid PDE solvers. Firstly, the quality of both the surface triangulations and tetrahedral meshes is guaranteed. Secondly, the interface in the tetrahedral mesh is an accurate approximation of the molecular boundary. In particular, all the boundary points lie on the skin surface. Thirdly, our meshes are Delaunay meshes. Finally, the meshes are adaptive to the geometry. PMID:21779137

Using EUNIS habitat classification for benthic mapping in European seas: present concerns and future needs.

PubMed

Galparsoro, Ibon; Connor, David W; Borja, Angel; Aish, Annabelle; Amorim, Patricia; Bajjouk, Touria; Chambers, Caroline; Coggan, Roger; Dirberg, Guillaume; Ellwood, Helen; Evans, Douglas; Goodin, Kathleen L; Grehan, Anthony; Haldin, Jannica; Howell, Kerry; Jenkins, Chris; Michez, Noëmie; Mo, Giulia; Buhl-Mortensen, Pål; Pearce, Bryony; Populus, Jacques; Salomidi, Maria; Sánchez, Francisco; Serrano, Alberto; Shumchenia, Emily; Tempera, Fernando; Vasquez, Mickaël

2012-12-01

The EUNIS (European Union Nature Information System) habitat classification system aims to provide a common European reference set of habitat types within a hierarchical classification, and to cover all terrestrial, freshwater and marine habitats of Europe. The classification facilitates reporting of habitat data in a comparable manner, for use in nature conservation (e.g. inventories, monitoring and assessments), habitat mapping and environmental management. For the marine environment the importance of a univocal habitat classification system is confirmed by the fact that many European initiatives, aimed at marine mapping, assessment and reporting, are increasingly using EUNIS habitat categories and respective codes. For this reason substantial efforts have been made to include information on marine benthic habitats from different regions, aiming to provide a comprehensive geographical coverage of European seas. However, there still remain many concerns on its applicability as only a small fraction of Europe's seas are fully mapped and increasing knowledge and application raise further issues to be resolved. This paper presents an overview of the main discussion and conclusions of a workshop, organised by the MeshAtlantic project, focusing upon the experience in using the EUNIS habitats classification across different countries and seas, together with case studies. The aims of the meeting were to: (i) bring together scientists with experience in the use of the EUNIS marine classification and representatives from the European Environment Agency (EEA); (ii) agree on enhancements to EUNIS that ensure an improved representation of the European marine habitats; and (iii) establish practices that make marine habitat maps produced by scientists more consistent with the needs of managers and decision-makers. During the workshop challenges for the future development of EUNIS were identified, which have been classified into five categories: (1) structure and hierarchy; (2) biology; (3) terminology; (4) mapping; and (5) future development. The workshop ended with a declaration from the attendees, with recommendations to the EEA and European Topic Centre on Biological Diversity, to take into account the outputs of the workshop, which identify weaknesses in the current classification and include proposals for its modification, and to devise a process to further develop the marine component of the EUNIS habitat classification. Copyright © 2012 Elsevier Ltd. All rights reserved.

User Manual for the PROTEUS Mesh Tools

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Micheal A.; Shemon, Emily R.

2015-06-01

This report describes the various mesh tools that are provided with the PROTEUS code giving both descriptions of the input and output. In many cases the examples are provided with a regression test of the mesh tools. The most important mesh tools for any user to consider using are the MT_MeshToMesh.x and the MT_RadialLattice.x codes. The former allows the conversion between most mesh types handled by PROTEUS while the second allows the merging of multiple (assembly) meshes into a radial structured grid. Note that the mesh generation process is recursive in nature and that each input specific for a givenmore » mesh tool (such as .axial or .merge) can be used as “mesh” input for any of the mesh tools discussed in this manual.« less

Creating a classification of image types in the medical literature for visual categorization

NASA Astrophysics Data System (ADS)

Müller, Henning; Kalpathy-Cramer, Jayashree; Demner-Fushman, Dina; Antani, Sameer

2012-02-01

Content-based image retrieval (CBIR) from specialized collections has often been proposed for use in such areas as diagnostic aid, clinical decision support, and teaching. The visual retrieval from broad image collections such as teaching files, the medical literature or web images, by contrast, has not yet reached a high maturity level compared to textual information retrieval. Visual image classification into a relatively small number of classes (20-100) on the other hand, has shown to deliver good results in several benchmarks. It is, however, currently underused as a basic technology for retrieval tasks, for example, to limit the search space. Most classification schemes for medical images are focused on specific areas and consider mainly the medical image types (modalities), imaged anatomy, and view, and merge them into a single descriptor or classification hierarchy. Furthermore, they often ignore other important image types such as biological images, statistical figures, flowcharts, and diagrams that frequently occur in the biomedical literature. Most of the current classifications have also been created for radiology images, which are not the only types to be taken into account. With Open Access becoming increasingly widespread particularly in medicine, images from the biomedical literature are more easily available for use. Visual information from these images and knowledge that an image is of a specific type or medical modality could enrich retrieval. This enrichment is hampered by the lack of a commonly agreed image classification scheme. This paper presents a hierarchy for classification of biomedical illustrations with the goal of using it for visual classification and thus as a basis for retrieval. The proposed hierarchy is based on relevant parts of existing terminologies, such as the IRMA-code (Image Retrieval in Medical Applications), ad hoc classifications and hierarchies used in imageCLEF (Image retrieval task at the Cross-Language Evaluation Forum) and NLM's (National Library of Medicine) OpenI. Furtheron, mappings to NLM's MeSH (Medical Subject Headings), RSNA's RadLex (Radiological Society of North America, Radiology Lexicon), and the IRMA code are also attempted for relevant image types. Advantages derived from such hierarchical classification for medical image retrieval are being evaluated through benchmarks such as imageCLEF, and R&D systems such as NLM's OpenI. The goal is to extend this hierarchy progressively and (through adding image types occurring in the biomedical literature) to have a terminology for visual image classification based on image types distinguishable by visual means and occurring in the medical open access literature.

A Cognitive Computing Approach for Classification of Complaints in the Insurance Industry

NASA Astrophysics Data System (ADS)

Forster, J.; Entrup, B.

2017-10-01

In this paper we present and evaluate a cognitive computing approach for classification of dissatisfaction and four complaint specific complaint classes in correspondence documents between insurance clients and an insurance company. A cognitive computing approach includes the combination classical natural language processing methods, machine learning algorithms and the evaluation of hypothesis. The approach combines a MaxEnt machine learning algorithm with language modelling, tf-idf and sentiment analytics to create a multi-label text classification model. The result is trained and tested with a set of 2500 original insurance communication documents written in German, which have been manually annotated by the partnering insurance company. With a F1-Score of 0.9, a reliable text classification component has been implemented and evaluated. A final outlook towards a cognitive computing insurance assistant is given in the end.

Automatic document classification of biological literature

PubMed Central

Chen, David; Müller, Hans-Michael; Sternberg, Paul W

2006-01-01

Background Document classification is a wide-spread problem with many applications, from organizing search engine snippets to spam filtering. We previously described Textpresso, a text-mining system for biological literature, which marks up full text according to a shallow ontology that includes terms of biological interest. This project investigates document classification in the context of biological literature, making use of the Textpresso markup of a corpus of Caenorhabditis elegans literature. Results We present a two-step text categorization algorithm to classify a corpus of C. elegans papers. Our classification method first uses a support vector machine-trained classifier, followed by a novel, phrase-based clustering algorithm. This clustering step autonomously creates cluster labels that are descriptive and understandable by humans. This clustering engine performed better on a standard test-set (Reuters 21578) compared to previously published results (F-value of 0.55 vs. 0.49), while producing cluster descriptions that appear more useful. A web interface allows researchers to quickly navigate through the hierarchy and look for documents that belong to a specific concept. Conclusion We have demonstrated a simple method to classify biological documents that embodies an improvement over current methods. While the classification results are currently optimized for Caenorhabditis elegans papers by human-created rules, the classification engine can be adapted to different types of documents. We have demonstrated this by presenting a web interface that allows researchers to quickly navigate through the hierarchy and look for documents that belong to a specific concept. PMID:16893465

User Manual for the PROTEUS Mesh Tools

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Micheal A.; Shemon, Emily R

2016-09-19

PROTEUS is built around a finite element representation of the geometry for visualization. In addition, the PROTEUS-SN solver was built to solve the even-parity transport equation on a finite element mesh provided as input. Similarly, PROTEUS-MOC and PROTEUS-NEMO were built to apply the method of characteristics on unstructured finite element meshes. Given the complexity of real world problems, experience has shown that using commercial mesh generator to create rather simple input geometries is overly complex and slow. As a consequence, significant effort has been put into place to create multiple codes that help assist in the mesh generation and manipulation.more » There are three input means to create a mesh in PROTEUS: UFMESH, GRID, and NEMESH. At present, the UFMESH is a simple way to generate two-dimensional Cartesian and hexagonal fuel assembly geometries. The UFmesh input allows for simple assembly mesh generation while the GRID input allows the generation of Cartesian, hexagonal, and regular triangular structured grid geometry options. The NEMESH is a way for the user to create their own mesh or convert another mesh file format into a PROTEUS input format. Given that one has an input mesh format acceptable for PROTEUS, we have constructed several tools which allow further mesh and geometry construction (i.e. mesh extrusion and merging). This report describes the various mesh tools that are provided with the PROTEUS code giving both descriptions of the input and output. In many cases the examples are provided with a regression test of the mesh tools. The most important mesh tools for any user to consider using are the MT_MeshToMesh.x and the MT_RadialLattice.x codes. The former allows the conversion between most mesh types handled by PROTEUS while the second allows the merging of multiple (assembly) meshes into a radial structured grid. Note that the mesh generation process is recursive in nature and that each input specific for a given mesh tool (such as .axial or .merge) can be used as “mesh” input for any of the mesh tools discussed in this manual.« less

Image Engine: an object-oriented multimedia database for storing, retrieving and sharing medical images and text.

PubMed Central

Lowe, H. J.

1993-01-01

This paper describes Image Engine, an object-oriented, microcomputer-based, multimedia database designed to facilitate the storage and retrieval of digitized biomedical still images, video, and text using inexpensive desktop computers. The current prototype runs on Apple Macintosh computers and allows network database access via peer to peer file sharing protocols. Image Engine supports both free text and controlled vocabulary indexing of multimedia objects. The latter is implemented using the TView thesaurus model developed by the author. The current prototype of Image Engine uses the National Library of Medicine's Medical Subject Headings (MeSH) vocabulary (with UMLS Meta-1 extensions) as its indexing thesaurus. PMID:8130596

First case of mesh infection due to Coccidioides spp. and literature review of fungal mesh infections after hernia repair.

PubMed

Forrester, Joseph D; Gomez, Carlos A; Forrester, Jared A; Nguyen, Mike; Gregg, David; Deresinski, Stan; Banaei, Niaz; Weiser, Thomas G

2015-10-01

Fungal mesh infections are a rare complication of hernia repairs with mesh. The first case of Coccidioides spp. mesh infection is described, and a systematic literature review of all known fungal mesh infections was performed. Nine cases of fungal mesh infection are reviewed. Female and male patients are equally represented, median age is 49.5 years, and critical illness and preinfection antibiotic use were common. Fungal mesh infections are rare, but potentially fatal, complications of hernias repaired with mesh. © 2015 Blackwell Verlag GmbH.

41 CFR Appendix B to Part 60 - 300-Sample Invitation to Self-Identify

Code of Federal Regulations, 2014 CFR

2014-07-01

... classifications are defined as follows: • A “disabled veteran” is one of the following: • a veteran of the U.S...). THE DEFINITIONS OF THE SEPARATE CLASSIFICATIONS OF PROTECTED VETERANS SET FORTH IN PARAGRAPH 1 MUST... CLASSIFICATIONS OFPROTECTED VETERAN LISTED ABOVE [ ]I AM NOT A PROTECTED VETERAN [THE FOLLOWING TEXT SHOULD BE...

An Adaptive Mesh Algorithm: Mapping the Mesh Variables

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scannapieco, Anthony J.

2016-07-25

Both thermodynamic and kinematic variables must be mapped. The kinematic variables are defined on a separate kinematic mesh; it is the duel mesh to the thermodynamic mesh. The map of the kinematic variables is done by calculating the contributions of kinematic variables on the old thermodynamic mesh, mapping the kinematic variable contributions onto the new thermodynamic mesh and then synthesizing the mapped kinematic variables on the new kinematic mesh. In this document the map of the thermodynamic variables will be described.

Evaluation on Compressive Characteristics of Medical Stents Applied by Mesh Structures

NASA Astrophysics Data System (ADS)

Hirayama, Kazuki; He, Jianmei

2017-11-01

There are concerns about strength reduction and fatigue fracture due to stress concentration in currently used medical stents. To address these problems, meshed stents applied by mesh structures were interested for achieving long life and high strength perfromance of medical stents. The purpose of this study is to design basic mesh shapes to obatin three dimensional (3D) meshed stent models for mechanical property evaluation. The influence of introduced design variables on compressive characteristics of meshed stent models are evaluated through finite element analysis using ANSYS Workbench code. From the analytical results, the compressive stiffness are changed periodically with compressive directions, average results need to be introduced as the mean value of compressive stiffness of meshed stents. Secondly, compressive flexibility of meshed stents can be improved by increasing the angle proportional to the arm length of the mesh basic shape. By increasing the number of basic mesh shapes arranged in stent’s circumferential direction, compressive rigidity of meshed stent tends to be increased. Finaly reducing the mesh line width is found effective to improve compressive flexibility of meshed stents.

Mesh control information of windmill designed by Solidwork program

NASA Astrophysics Data System (ADS)

Mulyana, T.; Sebayang, D.; Rafsanjani, A. M. D.; Adani, J. H. D.; Muhyiddin, Y. S.

2017-12-01

This paper presents the mesh control information imposed on the windmill already designed. The accuracy of Simulation results is influenced by the quality of the created mesh. However, compared to the quality of the mesh is made, the simulation time running will be done software also increases. The smaller the size of the elements created when making the mesh, the better the mesh quality will be generated. When adjusting the mesh size, there is a slider that acts as the density regulator of the element. SolidWorks Simulation also has Mesh Control facility. Features that can adjust mesh density only in the desired part. The best results of mesh control obtained for both static and thermal simulation have ratio 1.5.

New Framework for Cross-Domain Document Classification

DTIC Science & Technology

2011-03-01

classification. The following paragraphs will introduce these related works in more detail. Wang et al . attempted to improve the accuracy of text document...of using Wikipedia to develop a thesaurus [20]. Gabrilovich et al . had an approach that is more elaborate in its use of Wikipedia text [21]. The...did show a modest improvement when it is performed using the Wikipedia information. Wang et al . improved on the results of co-clustering algorithm [24

Biomedical literature classification using encyclopedic knowledge: a Wikipedia-based bag-of-concepts approach.

PubMed

Mouriño García, Marcos Antonio; Pérez Rodríguez, Roberto; Anido Rifón, Luis E

2015-01-01

Automatic classification of text documents into a set of categories has a lot of applications. Among those applications, the automatic classification of biomedical literature stands out as an important application for automatic document classification strategies. Biomedical staff and researchers have to deal with a lot of literature in their daily activities, so it would be useful a system that allows for accessing to documents of interest in a simple and effective way; thus, it is necessary that these documents are sorted based on some criteria-that is to say, they have to be classified. Documents to classify are usually represented following the bag-of-words (BoW) paradigm. Features are words in the text-thus suffering from synonymy and polysemy-and their weights are just based on their frequency of occurrence. This paper presents an empirical study of the efficiency of a classifier that leverages encyclopedic background knowledge-concretely Wikipedia-in order to create bag-of-concepts (BoC) representations of documents, understanding concept as "unit of meaning", and thus tackling synonymy and polysemy. Besides, the weighting of concepts is based on their semantic relevance in the text. For the evaluation of the proposal, empirical experiments have been conducted with one of the commonly used corpora for evaluating classification and retrieval of biomedical information, OHSUMED, and also with a purpose-built corpus of MEDLINE biomedical abstracts, UVigoMED. Results obtained show that the Wikipedia-based bag-of-concepts representation outperforms the classical bag-of-words representation up to 157% in the single-label classification problem and up to 100% in the multi-label problem for OHSUMED corpus, and up to 122% in the single-label classification problem and up to 155% in the multi-label problem for UVigoMED corpus.

Evidence for the use of "medical marijuana" in psychiatric and neurologic disorders.

PubMed

Noel, Christopher

2017-01-01

Cannabis is listed as a Schedule I substance under the Controlled Substances Act of 1970, meaning the US federal government defines it as an illegal drug that has high potential for abuse and no established medical use; however, half of the states in the nation have enacted "medical marijuana" (MM) laws. Clinicians must be aware of the evidence for and against the use of MM in their patients who may consider using this substance. A PubMed database search was performed using the text string: "Cannabis"[Mesh] OR "Marijuana Abuse"[Mesh] OR "Medical Marijuana"[Mesh] OR "Marijuana Smoking"[Mesh] OR "cannabi*" OR "tetrahydrocannabinol." The search was further limited to randomized clinical trial publications in English on human subjects to identify articles regarding the therapeutic use of phytocannabinoids for psychiatric and neurologic disorders. Commercially available products (ie, dronabinol, nabilone, nabiximols) and synthetic cannabinoids were excluded from the review. Publications were identified that included patients with dementia, multiple sclerosis, Parkinson disease, Huntington disease, schizophrenia, social anxiety disorder, depression, tobacco use disorder, and neuropathic pain. There is great variety concerning which medical conditions are approved for treatment with MM for either palliative or therapeutic benefit, depending on the state law. It is important to keep an evidence-based approach in mind, even with substances considered to be illegal under US federal law. Clinicians must weigh risks and benefits of the use of MM in their patients and should ensure that patients have tried other treatment modalities with higher levels of evidence for use when available and appropriate.

Changes in pelvic organ prolapse mesh mechanical properties following implantation in rats.

PubMed

Ulrich, Daniela; Edwards, Sharon L; Alexander, David L J; Rosamilia, Anna; Werkmeister, Jerome A; Gargett, Caroline E; Letouzey, Vincent

2016-02-01

Pelvic organ prolapse (POP) is a multifactorial disease that manifests as the herniation of the pelvic organs into the vagina. Surgical methods for prolapse repair involve the use of a synthetic polypropylene mesh. The use of this mesh has led to significantly higher anatomical success rates compared with native tissue repairs, and therefore, despite recent warnings by the Food and Drug Administration regarding the use of vaginal mesh, the number of POP mesh surgeries has increased over the last few years. However, mesh implantation is associated with higher postsurgery complications, including pain and erosion, with higher consecutive rates of reoperation when placed vaginally. Little is known on how the mechanical properties of the implanted mesh itself change in vivo. It is assumed that the mechanical properties of these meshes remain unchanged, with any differences in mechanical properties of the formed mesh-tissue complex attributed to the attached tissue alone. It is likely that any changes in mesh mechanical properties that do occur in vivo will have an impact on the biomechanical properties of the formed mesh-tissue complex. The objective of the study was to assess changes in the multiaxial mechanical properties of synthetic clinical prolapse meshes implanted abdominally for up to 90 days, using a rat model. Another objective of the study was to assess the biomechanical properties of the formed mesh-tissue complex following implantation. Three nondegradable polypropylene clinical synthetic mesh types for prolapse repair (Gynemesh PS, Polyform Lite, and Restorelle) and a partially degradable polypropylene/polyglecaprone mesh (UltraPro) were mechanically assessed before and after implantation (n = 5/ mesh type) in Sprague Dawley rats for 30 (Gynemesh PS, Polyform Lite, and Restorelle) and 90 (UltraPro and Polyform Lite) days. Stiffness and permanent extension following cyclic loading, and breaking load, of the preimplanted mesh types, explanted mesh-tissue complexes, and explanted meshes were assessed using a multi-axial (ball-burst) method. The 4 clinical meshes varied from each other in weight, thickness, porosity, and pore size and showed significant differences in stiffness and breaking load before implantation. Following 30 days of implantation, the mechanical properties of some mesh types altered, with significant decreases in mesh stiffness and breaking load, and increased permanent extension. After 90 days these changes were more obvious, with significant decreases in stiffness and breaking load and increased permanent extension. Similar biomechanical properties of formed mesh-tissue complexes were observed for mesh types of different preimplant stiffness and structure after 90 days implantation. This is the first study to report on intrinsic changes in the mechanical properties of implanted meshes and how these changes have an impact on the estimated tissue contribution of the formed mesh-tissue complex. Decreased mesh stiffness, strength, and increased permanent extension following 90 days of implantation increase the biomechanical contribution of the attached tissue of the formed mesh-tissue complex more than previously thought. This needs to be considered when using meshes for prolapse repair. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

Radial cold trap

DOEpatents

Grundy, Brian R.

1981-01-01

The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume.

Radial cold trap

DOEpatents

Grundy, B.R.

1981-09-29

The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume. 2 figs.

Association Between the Amount of Vaginal Mesh Used With Mesh Erosions and Repeated Surgery After Repairing Pelvic Organ Prolapse and Stress Urinary Incontinence.

PubMed

Chughtai, Bilal; Barber, Matthew D; Mao, Jialin; Forde, James C; Normand, Sharon-Lise T; Sedrakyan, Art

2017-03-01

Mesh, a synthetic graft, has been used in pelvic organ prolapse (POP) repair and stress urinary incontinence (SUI) to augment and strengthen weakened tissue. Polypropylene mesh has come under scrutiny by the US Food and Drug Administration. To examine the rates of mesh complications and invasive reintervention after the placement of vaginal mesh for POP repair or SUI surgery. This investigation was an observational cohort study at inpatient and ambulatory surgery settings in New York State. Participants were women who underwent transvaginal repair for POP or SUI with mesh between January 1, 2008, and December 31, 2012, and were followed up through December 31, 2013. They were divided into the following 4 groups based on the amount of mesh exposure: transvaginal POP repair surgery with mesh and concurrent sling use (vaginal mesh plus sling group), transvaginal POP repair with mesh and no concurrent sling use (vaginal mesh group), transvaginal POP repair without mesh but concurrent sling use for SUI (POP sling group), and sling for SUI alone (SUI sling group). The primary outcome was the occurrence of mesh complications and repeated invasive intervention within 1 year after the initial mesh implantation. A time-to-event analysis was performed to examine the occurrence of mesh erosions and subsequent reintervention. Secondary analyses of an age association (<65 vs ≥65 years) were conducted. The study identified 41 604 women who underwent 1 of the 4 procedures. The mean (SD) age of women at their initial mesh implantation was 56.2 (13.0) years. The highest risk of erosions was found in the vaginal mesh plus sling group (2.72%; 95% CI, 2.31%-3.21%) and the lowest in the SUI sling group (1.57%; 95% CI, 1.41%-1.74%). The risk of repeated surgery with concomitant erosion diagnosis was also the highest in the vaginal mesh plus sling group (2.13%; 95% CI, 1.76%-2.56%) and the lowest in the SUI sling group (1.16%; 95% CI, 1.03%-1.31%). The combined use of POP mesh and SUI mesh sling was associated with the highest erosion and repeated intervention risk, while mesh sling alone had the lowest erosion and repeated intervention risk. There is evidence for a dose-response relationship between the amount of mesh used and subsequent mesh erosions, complications, and invasive repeated intervention.

Documentation for MeshKit - Reactor Geometry (&mesh) Generator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jain, Rajeev; Mahadevan, Vijay

2015-09-30

This report gives documentation for using MeshKit’s Reactor Geometry (and mesh) Generator (RGG) GUI and also briefly documents other algorithms and tools available in MeshKit. RGG is a program designed to aid in modeling and meshing of complex/large hexagonal and rectilinear reactor cores. RGG uses Argonne’s SIGMA interfaces, Qt and VTK to produce an intuitive user interface. By integrating a 3D view of the reactor with the meshing tools and combining them into one user interface, RGG streamlines the task of preparing a simulation mesh and enables real-time feedback that reduces accidental scripting mistakes that could waste hours of meshing.more » RGG interfaces with MeshKit tools to consolidate the meshing process, meaning that going from model to mesh is as easy as a button click. This report is designed to explain RGG v 2.0 interface and provide users with the knowledge and skills to pilot RGG successfully. Brief documentation of MeshKit source code, tools and other algorithms available are also presented for developers to extend and add new algorithms to MeshKit. RGG tools work in serial and parallel and have been used to model complex reactor core models consisting of conical pins, load pads, several thousands of axially varying material properties of instrumentation pins and other interstices meshes.« less

The Role of Chronic Mesh Infection in Delayed-Onset Vaginal Mesh Complications or Recurrent Urinary Tract Infections: Results From Explanted Mesh Cultures.

PubMed

Mellano, Erin M; Nakamura, Leah Y; Choi, Judy M; Kang, Diana C; Grisales, Tamara; Raz, Shlomo; Rodriguez, Larissa V

2016-01-01

Vaginal mesh complications necessitating excision are increasingly prevalent. We aim to study whether subclinical chronically infected mesh contributes to the development of delayed-onset mesh complications or recurrent urinary tract infections (UTIs). Women undergoing mesh removal from August 2013 through May 2014 were identified by surgical code for vaginal mesh removal. Only women undergoing removal of anti-incontinence mesh were included. Exclusion criteria included any women undergoing simultaneous prolapse mesh removal. We abstracted preoperative and postoperative information from the medical record and compared mesh culture results from patients with and without mesh extrusion, de novo recurrent UTIs, and delayed-onset pain. One hundred seven women with only anti-incontinence mesh removed were included in the analysis. Onset of complications after mesh placement was within the first 6 months in 70 (65%) of 107 and delayed (≥6 months) in 37 (35%) of 107. A positive culture from the explanted mesh was obtained from 82 (77%) of 107 patients, and 40 (37%) of 107 were positive with potential pathogens. There were no significant differences in culture results when comparing patients with delayed-onset versus immediate pain, extrusion with no extrusion, and de novo recurrent UTIs with no infections. In this large cohort of patients with mesh removed for a diverse array of complications, cultures of the explanted vaginal mesh demonstrate frequent low-density bacterial colonization. We found no differences in culture results from women with delayed-onset pain versus acute pain, vaginal mesh extrusions versus no extrusions, or recurrent UTIs using standard culture methods. Chronic prosthetic infections in other areas of medicine are associated with bacterial biofilms, which are resistant to typical culture techniques. Further studies using culture-independent methods are needed to investigate the potential role of chronic bacterial infections in delayed vaginal mesh complications.

Unsupervised Biomedical Named Entity Recognition: Experiments with Clinical and Biological Texts

PubMed Central

Zhang, Shaodian; Elhadad, Nóemie

2013-01-01

Named entity recognition is a crucial component of biomedical natural language processing, enabling information extraction and ultimately reasoning over and knowledge discovery from text. Much progress has been made in the design of rule-based and supervised tools, but they are often genre and task dependent. As such, adapting them to different genres of text or identifying new types of entities requires major effort in re-annotation or rule development. In this paper, we propose an unsupervised approach to extracting named entities from biomedical text. We describe a stepwise solution to tackle the challenges of entity boundary detection and entity type classification without relying on any handcrafted rules, heuristics, or annotated data. A noun phrase chunker followed by a filter based on inverse document frequency extracts candidate entities from free text. Classification of candidate entities into categories of interest is carried out by leveraging principles from distributional semantics. Experiments show that our system, especially the entity classification step, yields competitive results on two popular biomedical datasets of clinical notes and biological literature, and outperforms a baseline dictionary match approach. Detailed error analysis provides a road map for future work. PMID:23954592

Automated Authorship Attribution Using Advanced Signal Classification Techniques

PubMed Central

Ebrahimpour, Maryam; Putniņš, Tālis J.; Berryman, Matthew J.; Allison, Andrew; Ng, Brian W.-H.; Abbott, Derek

2013-01-01

In this paper, we develop two automated authorship attribution schemes, one based on Multiple Discriminant Analysis (MDA) and the other based on a Support Vector Machine (SVM). The classification features we exploit are based on word frequencies in the text. We adopt an approach of preprocessing each text by stripping it of all characters except a-z and space. This is in order to increase the portability of the software to different types of texts. We test the methodology on a corpus of undisputed English texts, and use leave-one-out cross validation to demonstrate classification accuracies in excess of 90%. We further test our methods on the Federalist Papers, which have a partly disputed authorship and a fair degree of scholarly consensus. And finally, we apply our methodology to the question of the authorship of the Letter to the Hebrews by comparing it against a number of original Greek texts of known authorship. These tests identify where some of the limitations lie, motivating a number of open questions for future work. An open source implementation of our methodology is freely available for use at https://github.com/matthewberryman/author-detection. PMID:23437047

Comparative analysis of histopathologic effects of synthetic meshes based on material, weight, and pore size in mice.

PubMed

Orenstein, Sean B; Saberski, Ean R; Kreutzer, Donald L; Novitsky, Yuri W

2012-08-01

While synthetic prosthetics have essentially become mandatory for hernia repair, mesh-induced chronic inflammation and scarring can lead to chronic pain and limited mobility. Mesh propensity to induce such adverse effects is likely related to the prosthetic's material, weight, and/or pore size. We aimed to compare histopathologic responses to various synthetic meshes after short- and long-term implantations in mice. Samples of macroporous polyester (Parietex [PX]), heavyweight microporous polypropylene (Trelex[TX]), midweight microporous polypropylene (ProLite[PL]), lightweight macroporous polypropylene (Ultrapro[UP]), and expanded polytetrafluoroethylene (DualMesh[DM]) were implanted subcutaneously in mice. Four and 12 wk post-implantation, meshes were assessed for inflammation, foreign body reaction (FBR), and fibrosis. All meshes induced varying levels of inflammatory responses. PX induced the greatest inflammatory response and marked FBR. DM induced moderate FBR and a strong fibrotic response with mesh encapsulation at 12 wk. UP and PL had the lowest FBR, however, UP induced a significant chronic inflammatory response. Although inflammation decreased slightly for TX, marked FBR was present throughout the study. Of the three polypropylene meshes, fibrosis was greatest for TX and slightly reduced for PL and UP. For UP and PL, there was limited fibrosis within each mesh pore. Polyester mesh induced the greatest FBR and lasting chronic inflammatory response. Likewise, marked fibrosis and encapsulation was seen surrounding ePTFE. Heavier polypropylene meshes displayed greater early and persistent fibrosis; the reduced-weight polypropylene meshes were associated with the least amount of fibrosis. Mesh pore size was inversely proportional to bridging fibrosis. Moreover, reduced-weight polypropylene meshes demonstrated the smallest FBR throughout the study. Overall, we demonstrated that macroporous, reduced-weight polypropylene mesh exhibited the highest degree of biocompatibility at sites of mesh implantation. Copyright © 2012 Elsevier Inc. All rights reserved.

What is the evidence for the use of biologic or biosynthetic meshes in abdominal wall reconstruction?

PubMed

Köckerling, F; Alam, N N; Antoniou, S A; Daniels, I R; Famiglietti, F; Fortelny, R H; Heiss, M M; Kallinowski, F; Kyle-Leinhase, I; Mayer, F; Miserez, M; Montgomery, A; Morales-Conde, S; Muysoms, F; Narang, S K; Petter-Puchner, A; Reinpold, W; Scheuerlein, H; Smietanski, M; Stechemesser, B; Strey, C; Woeste, G; Smart, N J

2018-04-01

Although many surgeons have adopted the use of biologic and biosynthetic meshes in complex abdominal wall hernia repair, others have questioned the use of these products. Criticism is addressed in several review articles on the poor standard of studies reporting on the use of biologic meshes for different abdominal wall repairs. The aim of this consensus review is to conduct an evidence-based analysis of the efficacy of biologic and biosynthetic meshes in predefined clinical situations. A European working group, "BioMesh Study Group", composed of invited surgeons with a special interest in surgical meshes, formulated key questions, and forwarded them for processing in subgroups. In January 2016, a workshop was held in Berlin where the findings were presented, discussed, and voted on for consensus. Findings were set out in writing by the subgroups followed by consensus being reached. For the review, 114 studies and background analyses were used. The cumulative data regarding biologic mesh under contaminated conditions do not support the claim that it is better than synthetic mesh. Biologic mesh use should be avoided when bridging is needed. In inguinal hernia repair biologic and biosynthetic meshes do not have a clear advantage over the synthetic meshes. For prevention of incisional or parastomal hernias, there is no evidence to support the use of biologic/biosynthetic meshes. In complex abdominal wall hernia repairs (incarcerated hernia, parastomal hernia, infected mesh, open abdomen, enterocutaneous fistula, and component separation technique), biologic and biosynthetic meshes do not provide a superior alternative to synthetic meshes. The routine use of biologic and biosynthetic meshes cannot be recommended.

Fusion and Sense Making of Heterogeneous Sensor Network and Other Sources

DTIC Science & Technology

2017-03-16

multimodal fusion framework that uses both training data and web resources for scene classification, the experimental results on the benchmark datasets...show that the proposed text-aided scene classification framework could significantly improve classification performance. Experimental results also show...human whose adaptability is achieved by reliability- dependent weighting of different sensory modalities. Experimental results show that the proposed

Toward An Unstructured Mesh Database

NASA Astrophysics Data System (ADS)

Rezaei Mahdiraji, Alireza; Baumann, Peter Peter

2014-05-01

Unstructured meshes are used in several application domains such as earth sciences (e.g., seismology), medicine, oceanography, cli- mate modeling, GIS as approximate representations of physical objects. Meshes subdivide a domain into smaller geometric elements (called cells) which are glued together by incidence relationships. The subdivision of a domain allows computational manipulation of complicated physical structures. For instance, seismologists model earthquakes using elastic wave propagation solvers on hexahedral meshes. The hexahedral con- tains several hundred millions of grid points and millions of hexahedral cells. Each vertex node in the hexahedrals stores a multitude of data fields. To run simulation on such meshes, one needs to iterate over all the cells, iterate over incident cells to a given cell, retrieve coordinates of cells, assign data values to cells, etc. Although meshes are used in many application domains, to the best of our knowledge there is no database vendor that support unstructured mesh features. Currently, the main tool for querying and manipulating unstructured meshes are mesh libraries, e.g., CGAL and GRAL. Mesh li- braries are dedicated libraries which includes mesh algorithms and can be run on mesh representations. The libraries do not scale with dataset size, do not have declarative query language, and need deep C++ knowledge for query implementations. Furthermore, due to high coupling between the implementations and input file structure, the implementations are less reusable and costly to maintain. A dedicated mesh database offers the following advantages: 1) declarative querying, 2) ease of maintenance, 3) hiding mesh storage structure from applications, and 4) transparent query optimization. To design a mesh database, the first challenge is to define a suitable generic data model for unstructured meshes. We proposed ImG-Complexes data model as a generic topological mesh data model which extends incidence graph model to multi-incidence relationships. We instrument ImG model with sets of optional and application-specific constraints which can be used to check validity of meshes for a specific class of object such as manifold, pseudo-manifold, and simplicial manifold. We conducted experiments to measure the performance of the graph database solution in processing mesh queries and compare it with GrAL mesh library and PostgreSQL database on synthetic and real mesh datasets. The experiments show that each system perform well on specific types of mesh queries, e.g., graph databases perform well on global path-intensive queries. In the future, we investigate database operations for the ImG model and design a mesh query language.

Improving Classification of Protein Interaction Articles Using Context Similarity-Based Feature Selection.

PubMed

Chen, Yifei; Sun, Yuxing; Han, Bing-Qing

2015-01-01

Protein interaction article classification is a text classification task in the biological domain to determine which articles describe protein-protein interactions. Since the feature space in text classification is high-dimensional, feature selection is widely used for reducing the dimensionality of features to speed up computation without sacrificing classification performance. Many existing feature selection methods are based on the statistical measure of document frequency and term frequency. One potential drawback of these methods is that they treat features separately. Hence, first we design a similarity measure between the context information to take word cooccurrences and phrase chunks around the features into account. Then we introduce the similarity of context information to the importance measure of the features to substitute the document and term frequency. Hence we propose new context similarity-based feature selection methods. Their performance is evaluated on two protein interaction article collections and compared against the frequency-based methods. The experimental results reveal that the context similarity-based methods perform better in terms of the F1 measure and the dimension reduction rate. Benefiting from the context information surrounding the features, the proposed methods can select distinctive features effectively for protein interaction article classification.

The impact of hydrophobic hernia mesh coating by omega fatty acid on atraumatic fibrin sealant fixation.

PubMed

Gruber-Blum, S; Brand, J; Keibl, C; Redl, H; Fortelny, R H; May, C; Petter-Puchner, A H

2015-08-01

Fibrin sealant (FS) is a safe and efficient fixation method in open intraperitoneal hernia repair. While favourable results have been achieved with hydrophilic meshes, hydrophobic (such as Omega fatty acid coated) meshes (OFM) have not been specifically assessed so far. Atrium C-qur lite(®) mesh was tested in rats in models of open onlay and intraperitoneal hernia repair. 44 meshes (2 × 2 cm) were implanted in 30 male Sprague-Dawley rats in open (n = 2 meshes per animal) and intraperitoneal technique (IPOM; n = 1 mesh per animal). Animals were randomised to four groups: onlay and IPOM sutured vs. sealed. Follow-up was 6 weeks, sutured groups serving as controls. Evaluation criteria were mesh dislocation, adhesions and foreign body reaction. FS provided a reliable fixation in onlay technique, whereas OFM meshes dislocated in the IPOM position when sealed only. FS mesh fixation was safe with OFM meshes in open onlay repair. Intraperitoneal placement of hydrophobic meshes requires additional fixation and cannot be achieved with FS alone.

Enhancing navigation in biomedical databases by community voting and database-driven text classification

PubMed Central

Duchrow, Timo; Shtatland, Timur; Guettler, Daniel; Pivovarov, Misha; Kramer, Stefan; Weissleder, Ralph

2009-01-01

Background The breadth of biological databases and their information content continues to increase exponentially. Unfortunately, our ability to query such sources is still often suboptimal. Here, we introduce and apply community voting, database-driven text classification, and visual aids as a means to incorporate distributed expert knowledge, to automatically classify database entries and to efficiently retrieve them. Results Using a previously developed peptide database as an example, we compared several machine learning algorithms in their ability to classify abstracts of published literature results into categories relevant to peptide research, such as related or not related to cancer, angiogenesis, molecular imaging, etc. Ensembles of bagged decision trees met the requirements of our application best. No other algorithm consistently performed better in comparative testing. Moreover, we show that the algorithm produces meaningful class probability estimates, which can be used to visualize the confidence of automatic classification during the retrieval process. To allow viewing long lists of search results enriched by automatic classifications, we added a dynamic heat map to the web interface. We take advantage of community knowledge by enabling users to cast votes in Web 2.0 style in order to correct automated classification errors, which triggers reclassification of all entries. We used a novel framework in which the database "drives" the entire vote aggregation and reclassification process to increase speed while conserving computational resources and keeping the method scalable. In our experiments, we simulate community voting by adding various levels of noise to nearly perfectly labelled instances, and show that, under such conditions, classification can be improved significantly. Conclusion Using PepBank as a model database, we show how to build a classification-aided retrieval system that gathers training data from the community, is completely controlled by the database, scales well with concurrent change events, and can be adapted to add text classification capability to other biomedical databases. The system can be accessed at . PMID:19799796

Automated interpretation of home blood pressure assessment (Hy-Result software) versus physician's assessment: a validation study.

PubMed

Postel-Vinay, Nicolas; Bobrie, Guillaume; Ruelland, Alan; Oufkir, Majida; Savard, Sebastien; Persu, Alexandre; Katsahian, Sandrine; Plouin, Pierre F

2016-04-01

Hy-Result is the first software for self-interpretation of home blood pressure measurement results, taking into account both the recommended thresholds for normal values and patient characteristics. We compare the software-generated classification with the physician's evaluation. The primary assessment criterion was whether algorithm classification of the blood pressure (BP) status concurred with the physician's advice (blinded to the software's results) following a consultation (n=195 patients). Secondary assessment was the reliability of text messages. In the 58 untreated patients, the agreement between classification of the BP status generated by the software and the physician's classification was 87.9%. In the 137 treated patients, the agreement was 91.9%. The κ-test applied for all the patients was 0.81 (95% confidence interval: 0.73-0.89). After correction of errors identified in the algorithm during the study, agreement increased to 95.4% [κ=0.9 (95% confidence interval: 0.84-0.97)]. For 100% of the patients with comorbidities (n=46), specific text messages were generated, indicating that a physician might recommend a target BP lower than 135/85 mmHg. Specific text messages were also generated for 100% of the patients for whom global cardiovascular risks markedly exceeded norms. Classification by Hy-Result is at least as accurate as that of a specialist in current practice (http://www.hy-result.com).

Preparation and biocompatibility evaluation of polypropylene mesh coated with electrospinning membrane for pelvic defects repair.

PubMed

Lu, Yao; Fu, Shaoju; Zhou, Shuanglin; Chen, Ge; Zhu, Chaoting; Li, Nannan; Ma, Ying

2018-05-01

Composite mesh with different materials composition could compensate for the drawbacks brought by single component mesh. Coating a membrane layer on the surface of macroporous mesh is a common method for preparing composite medical mesh. Electrospinning and dipping methods were introduced to form the two kinds of membrane-coated PP meshes (electro-mesh and dip-mesh); several properties were measured based on subcutaneous implantation model in rat. The results revealed that continuous tissue ingrowth could be observed for electro-mesh only with evidences of strength increase (electro-mesh: 0 week - 13.1 ± 0.88 N, 2 week - 16.87 ± 1.39 N, 4 week - 22.04 ± 2.05 N) and thickness increase (electro-mesh: 0 week - 0.437 ± 0.023 mm, 2 week - 0.488 ± 0.025 mm, 4 week - 0.576 ± 0.028 mm). However, no tissues were observed for dip-mesh in the first 2 weeks, both on macroscopic level and microscopic level, proved by strength data (dip-mesh: 0 week - 13.36 ± 1.06 N, 2 week - 13.4 ± 1.33 N, 4 week - 18.61 ± 1.89 N) and thickness data (dip-mesh: 0 week - 0.439 ± 0.018 mm, 2 week - 0.439 ± 0.019 mm, 4 week - 0.502 ± 0.032 mm). Electro-mesh had larger surface area decrease (10.74 ± 1.22%) than that of dip-mesh (2.78 ± 0.52%). The adhesion level of electro-mesh (medium adhesion) was also higher than that of dip-mesh (mild adhesion). Even if showing differences in several properties, both meshes were similar under histological observation, with the ability to support fresh tissues ingrowth. Considering operation environment, electro-mesh seems more suitable than dip-mesh with a rapid tissue growing, medium adhesion rate for repairing pelvic floor defects. Copyright © 2018 Elsevier Ltd. All rights reserved.

Method of and apparatus for modeling interactions

DOEpatents

Budge, Kent G.

2004-01-13

A method and apparatus for modeling interactions can accurately model tribological and other properties and accommodate topological disruptions. Two portions of a problem space are represented, a first with a Lagrangian mesh and a second with an ALE mesh. The ALE and Lagrangian meshes are constructed so that each node on the surface of the Lagrangian mesh is in a known correspondence with adjacent nodes in the ALE mesh. The interaction can be predicted for a time interval. Material flow within the ALE mesh can accurately model complex interactions such as bifurcation. After prediction, nodes in the ALE mesh in correspondence with nodes on the surface of the Lagrangian mesh can be mapped so that they are once again adjacent to their corresponding Lagrangian mesh nodes. The ALE mesh can then be smoothed to reduce mesh distortion that might reduce the accuracy or efficiency of subsequent prediction steps. The process, from prediction through mapping and smoothing, can be repeated until a terminal condition is reached.

Biocompatibility and tissue integration of a novel shape memory surgical mesh for ventral hernia: In vivo animal studies

PubMed Central

Zimkowski, Michael M.; Rentschler, Mark E.; Schoen, Jonathan A.; Mandava, Nageswara; Shandas, Robin

2014-01-01

Approximately 400,000 ventral hernia repair surgeries are performed each year in the United States. Many of these procedures are performed using laparoscopic minimally invasive techniques and employ the use of surgical mesh. The use of surgical mesh has been shown to reduce recurrence rates compared to standard suture repairs. The placement of surgical mesh in a ventral hernia repair procedure can be challenging, and may even complicate the procedure. Others have attempted to provide commercial solutions to the problems of mesh placement, but these have not been well accepted by the clinical community. In this article, two versions of shape memory polymer (SMP)-modified surgical mesh, and unmodified surgical mesh, were compared by performing laparoscopic manipulation in an acute porcine model. Also, SMP-integrated polyester surgical meshes were implanted in four rats for 30–33 days to evaluate chronic biocompatibility and capacity for tissue integration. Porcine results show that the modified mesh provides a controlled, temperature-activated, automated deployment when compared to an unmodified mesh. In rats, results indicate that implanted SMP-modified meshes exhibit exceptional biocompatibility and excellent integration with surrounding tissue with no noticeable differences from the unmodified counterpart. This article provides further evidence that an SMP-modified surgical mesh promises reduction in surgical placement time and that such a mesh is not substantially different from unmodified meshes in chronic biocompatibility. PMID:24327401

The effect of fabric structure on the mechanical properties of warp knitted surgical mesh for hernia repair.

PubMed

Mirjavan, Mohammad; Asayesh, Azita; Asgharian Jeddi, Ali Asghar

2017-02-01

Surgical mesh is being used for healing hernia, pelvic organ prolapse, skull injuries and urinary incontinence. In this research the effect of fabric structure on the mechanical properties of warp knitted surgical meshes in comparison to abdominal fascia has been investigated. For this purpose, warp knitted surgical mesh with five different structures (Tricot, Pin-hole-net, quasi-Sandfly, Sandfly and quasi-Marquissite) were produced using polypropylene monofilament. Thereafter, their mechanical properties such as uniaxial tensile behavior in various directions (wale-wise (90°), course-wise (0°) and diagonal (45°)), bending resistance and crease recovery were analyzed. The meshes demonstrated different elastic modulus in various directions, which can be attributed to the pore shape (pore angle) and underlap angle in the structure of mesh. Except Pin-hole-net mesh, other produced meshes exhibited better level of orthotropy in comparison to abdominal fascia. The most flexible mesh in both wale-wise and course-wise directions was quasi-Sandfly and thereafter quasi-Marquissite. Tricot and Pin-hole-net manifested the highest crease recovery in wale-wise and coursewise directions respectively. The most desirable mesh in terms of porosity was quasi-Marquissite mesh. Overall, the quasi-Marquissite mesh was selected as the most suitable surgical mesh considering all advantages and disadvantages of each produced mesh in this study. Copyright © 2016 Elsevier Ltd. All rights reserved.

Highly Symmetric and Congruently Tiled Meshes for Shells and Domes

PubMed Central

Rasheed, Muhibur; Bajaj, Chandrajit

2016-01-01

We describe the generation of all possible shell and dome shapes that can be uniquely meshed (tiled) using a single type of mesh face (tile), and following a single meshing (tiling) rule that governs the mesh (tile) arrangement with maximal vertex, edge and face symmetries. Such tiling arrangements or congruently tiled meshed shapes, are frequently found in chemical forms (fullerenes or Bucky balls, crystals, quasi-crystals, virus nano shells or capsids), and synthetic shapes (cages, sports domes, modern architectural facades). Congruently tiled meshes are both aesthetic and complete, as they support maximal mesh symmetries with minimal complexity and possess simple generation rules. Here, we generate congruent tilings and meshed shape layouts that satisfy these optimality conditions. Further, the congruent meshes are uniquely mappable to an almost regular 3D polyhedron (or its dual polyhedron) and which exhibits face-transitive (and edge-transitive) congruency with at most two types of vertices (each type transitive to the other). The family of all such congruently meshed polyhedra create a new class of meshed shapes, beyond the well-studied regular, semi-regular and quasi-regular classes, and their duals (platonic, Catalan and Johnson). While our new mesh class is infinite, we prove that there exists a unique mesh parametrization, where each member of the class can be represented by two integer lattice variables, and moreover efficiently constructable. PMID:27563368

Sirolimus-coated, poly(L-lactic acid)-modified polypropylene mesh with minimal intra-peritoneal adhesion formation in a rat model.

PubMed

Lu, S; Hu, W; Zhang, Z; Ji, Z; Zhang, T

2018-05-18

This study evaluated the manufacturing method and anti-adhesion properties of a new composite mesh in the rat model, which was made from sirolimus (SRL) grafts on a poly(L-lactic acid) (PLLA)-modified polypropylene (PP) hernia mesh. PLLA was first grafted onto argon-plasma-treated native PP mesh through catalysis of stannous chloride. SRL was grafted onto the surface of PP-PLLA meshes using catalysis of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 4-dimethylaminopyridine (DMAP) in a CH 2 Cl 2 solvent. Sprague-Dawley female rats received either SRL-coated meshes, PP-PLLA meshes, or native PP meshes to repair abdominal wall defects. At different intervals, rats were euthanized by a lethal dose of chloral hydrate and adhesion area and tenacity were evaluated. Sections of the mesh with adjacent tissues were assessed histologically. Attenuated total reflection Fourier transformed infrared (ATR-FTIR) spectroscopy indicated the existence of a C=O group absorption peak (1724.1 cm -1 ), and scanning electron microscope morphological analysis indicated that the surface of the PP mesh was covered with SRL. Compared to the native PP meshes and PP-PLLA meshes, SRL-coated meshes demonstrated the greatest ability to decrease the formation of adhesions (P < 0.05) and inflammation. The SRL-coated composite mesh showed minimal formation of intra-abdominal adhesions in a rat model of abdominal wall defect repair.

Fine-grained indexing of the biomedical literature: MeSH subheading attachment for a MEDLINE indexing tool.

PubMed

Névéol, Aurélie; Shooshan, Sonya E; Mork, James G; Aronson, Alan R

2007-10-11

This paper reports on the latest results of an Indexing Initiative effort addressing the automatic attachment of subheadings to MeSH main headings recommended by the NLM's Medical Text Indexer. Several linguistic and statistical approaches are used to retrieve and attach the subheadings. Continuing collaboration with NLM indexers also provided insight on how automatic methods can better enhance indexing practice. The methods were evaluated on corpus of 50,000 MEDLINE citations. For main heading/subheading pair recommendations, the best precision is obtained with a post-processing rule method (58%) while the best recall is obtained by pooling all methods (64%). For stand-alone subheading recommendations, the best performance is obtained with the PubMed Related Citations algorithm. Significant progress has been made in terms of subheading coverage. After further evaluation, some of this work may be integrated in the MEDLINE indexing workflow.

Fine-Grained Indexing of the Biomedical Literature: MeSH Subheading Attachment for a MEDLINE Indexing Tool

PubMed Central

Névéol, Aurélie; Shooshan, Sonya E.; Mork, James G.; Aronson, Alan R.

2007-01-01

Objective This paper reports on the latest results of an Indexing Initiative effort addressing the automatic attachment of subheadings to MeSH main headings recommended by the NLM’s Medical Text Indexer. Material and Methods Several linguistic and statistical approaches are used to retrieve and attach the subheadings. Continuing collaboration with NLM indexers also provided insight on how automatic methods can better enhance indexing practice. Results The methods were evaluated on corpus of 50,000 MEDLINE citations. For main heading/subheading pair recommendations, the best precision is obtained with a post-processing rule method (58%) while the best recall is obtained by pooling all methods (64%). For stand-alone subheading recommendations, the best performance is obtained with the PubMed Related Citations algorithm. Conclusion Significant progress has been made in terms of subheading coverage. After further evaluation, some of this work may be integrated in the MEDLINE indexing workflow. PMID:18693897

Surgical meshes coated with mesenchymal stem cells provide an anti-inflammatory environment by a M2 macrophage polarization.

PubMed

Blázquez, Rebeca; Sánchez-Margallo, Francisco Miguel; Álvarez, Verónica; Usón, Alejandra; Casado, Javier G

2016-02-01

Surgical meshes are widely used in clinics to reinforce soft tissue's defects, and to give support to prolapsed organs. However, the implantation of surgical meshes is commonly related with an inflammatory response being difficult to eradicate without removing the mesh. Here we hypothesize that the combined use of surgical meshes and mesenchymal stem cells (MSCs) could be a useful tool to reduce the inflammatory reaction secondary to mesh implantation. In vitro determinations of viability, metabolic activity and immunomodulation assays were performed on MSCs-coated meshes. Magnetic resonance imaging, evaluation by laparoscopic optical system and histology were performed for safety assessment. Finally, flow cytometry and qRT-PCR were used to elucidate the mechanism of action of MSCs-coated meshes. Our results demonstrate the feasibility to obtain MSCs-coated surgical meshes and their cryopreservability to be used as an 'off the shelf' product. These biological meshes fulfill the safety aspects as non-adverse effects were observed when compared to controls. Moreover, both in vitro and in vivo studies demonstrated that, local immunomodulation of implanted meshes is mediated by a macrophage polarization towards an anti-inflammatory phenotype. In conclusion, the combined usage of surgical meshes with MSCs fulfills the safety requirements for a future clinical application, providing an anti-inflammatory environment that could reduce the inflammatory processes commonly observed after surgical mesh implantation. Surgical meshes are medical devices widely used in clinics to resolve hernias and organs' prolapses, among other disorders. However, the implantation of surgical meshes is commonly related with an inflammatory response being difficult to eradicate without removing the mesh, causing pain and discomfort in the patient. Previously, the anti-inflammatory, immunomodulatory and pro-regenerative ability of mesenchymal stem cells (MSCs) have been described. To our knowledge, this is the first report where the anti-inflammatory and pro-regenerative ability of MSCs have been successfully applied in combination with surgical meshes, reducing the inflammatory processes commonly observed after mesh implantation. Moreover, our in vitro and in vivo results highlight the safety and efficacy of these bioactive meshes as a 'ready to use' medical product. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Bone Marrow–Derived Mesenchymal Stem Cells Enhance Bacterial Clearance and Preserve Bioprosthetic Integrity in a Model of Mesh Infection

PubMed Central

Criman, Erik T.; Kurata, Wendy E.; Matsumoto, Karen W.; Aubin, Harry T.; Campbell, Carmen E.

2016-01-01

Background: The reported incidence of mesh infection in contaminated operative fields is as high as 30% regardless of the material used. Recently, mesenchymal stem cells (MSCs) have been shown to possess favorable immunomodulatory properties and improve tissue incorporation when seeded onto bioprosthetics. The aim of this study was to evaluate whether seeding noncrosslinked bovine pericardium (Veritas Collagen Matrix) with allogeneic bone marrow–derived MSCs improves infection resistance in vivo after inoculation with Escherichia coli (E. coli). Methods: Rat bone marrow–derived MSCs at passage 3 were seeded onto bovine pericardium and cultured for 7 days before implantation. Additional rats (n = 24) were implanted subcutaneously with MSC-seeded or unseeded mesh and inoculated with 7 × 105 colony-forming units of E. coli or saline before wound closure (group 1, unseeded mesh/saline; group 2, unseeded mesh/E. coli; group 3, MSC-seeded mesh/E. coli; 8 rats per group). Meshes were explanted at 4 weeks and underwent microbiologic and histologic analyses. Results: MSC-seeded meshes inoculated with E. coli demonstrated superior bacterial clearance and preservation of mesh integrity compared with E. coli–inoculated unseeded meshes (87.5% versus 0% clearance; p = 0.001). Complete mesh degradation concurrent with abscess formation was observed in 100% of rats in the unseeded/E. coli group, which is in contrast to 12.5% of rats in the MSC-seeded/E. coli group. Histologic evaluation determined that remodeling characteristics of E. coli–inoculated MSC-seeded meshes were similar to those of uninfected meshes 4 weeks after implantation. Conclusions: Augmenting a bioprosthetic material with stem cells seems to markedly enhance resistance to bacterial infection in vivo and preserve mesh integrity. PMID:27482490

An adaptive mesh-moving and refinement procedure for one-dimensional conservation laws

NASA Technical Reports Server (NTRS)

Biswas, Rupak; Flaherty, Joseph E.; Arney, David C.

1993-01-01

We examine the performance of an adaptive mesh-moving and /or local mesh refinement procedure for the finite difference solution of one-dimensional hyperbolic systems of conservation laws. Adaptive motion of a base mesh is designed to isolate spatially distinct phenomena, and recursive local refinement of the time step and cells of the stationary or moving base mesh is performed in regions where a refinement indicator exceeds a prescribed tolerance. These adaptive procedures are incorporated into a computer code that includes a MacCormack finite difference scheme wih Davis' artificial viscosity model and a discretization error estimate based on Richardson's extrapolation. Experiments are conducted on three problems in order to qualify the advantages of adaptive techniques relative to uniform mesh computations and the relative benefits of mesh moving and refinement. Key results indicate that local mesh refinement, with and without mesh moving, can provide reliable solutions at much lower computational cost than possible on uniform meshes; that mesh motion can be used to improve the results of uniform mesh solutions for a modest computational effort; that the cost of managing the tree data structure associated with refinement is small; and that a combination of mesh motion and refinement reliably produces solutions for the least cost per unit accuracy.

Introducing a distributed unstructured mesh into gyrokinetic particle-in-cell code, XGC

NASA Astrophysics Data System (ADS)

Yoon, Eisung; Shephard, Mark; Seol, E. Seegyoung; Kalyanaraman, Kaushik

2017-10-01

XGC has shown good scalability for large leadership supercomputers. The current production version uses a copy of the entire unstructured finite element mesh on every MPI rank. Although an obvious scalability issue if the mesh sizes are to be dramatically increased, the current approach is also not optimal with respect to data locality of particles and mesh information. To address these issues we have initiated the development of a distributed mesh PIC method. This approach directly addresses the base scalability issue with respect to mesh size and, through the use of a mesh entity centric view of the particle mesh relationship, provides opportunities to address data locality needs of many core and GPU supported heterogeneous systems. The parallel mesh PIC capabilities are being built on the Parallel Unstructured Mesh Infrastructure (PUMI). The presentation will first overview the form of mesh distribution used and indicate the structures and functions used to support the mesh, the particles and their interaction. Attention will then focus on the node-level optimizations being carried out to ensure performant operation of all PIC operations on the distributed mesh. Partnership for Edge Physics Simulation (EPSI) Grant No. DE-SC0008449 and Center for Extended Magnetohydrodynamic Modeling (CEMM) Grant No. DE-SC0006618.

Hexahedral Mesh Untangling

DOE Office of Scientific and Technical Information (OSTI.GOV)

KNUPP,PATRICK

2000-12-13

We investigate a well-motivated mesh untangling objective function whose optimization automatically produces non-inverted elements when possible. Examples show the procedure is highly effective on simplicial meshes and on non-simplicial (e.g., hexahedral) meshes constructed via mapping or sweeping algorithms. The current whisker-weaving (WW) algorithm in CUBIT usually produces hexahedral meshes that are unsuitable for analyses due to inverted elements. The majority of these meshes cannot be untangled using the new objective function. The most likely source of the difficulty is poor mesh topology.

Method of modifying a volume mesh using sheet extraction

DOEpatents

Borden, Michael J [Albuquerque, NM; Shepherd, Jason F [Albuquerque, NM

2007-02-20

A method and machine-readable medium provide a technique to modify a hexahedral finite element volume mesh using dual generation and sheet extraction. After generating a dual of a volume stack (mesh), a predetermined algorithm may be followed to modify the volume mesh of hexahedral elements. The predetermined algorithm may include the steps of determining a sheet of hexahedral mesh elements, generating nodes for merging, and merging the nodes to delete the sheet of hexahedral mesh elements and modify the volume mesh.

Comparison of the fracture resistances of glass fiber mesh- and metal mesh-reinforced maxillary complete denture under dynamic fatigue loading.

PubMed

Im, So-Min; Huh, Yoon-Hyuk; Cho, Lee-Ra; Park, Chan-Jin

2017-02-01

The aim of this study was to investigate the effect of reinforcing materials on the fracture resistances of glass fiber mesh- and Cr-Co metal mesh-reinforced maxillary complete dentures under fatigue loading. Glass fiber mesh- and Cr-Co mesh-reinforced maxillary complete dentures were fabricated using silicone molds and acrylic resin. A control group was prepared with no reinforcement (n = 15 per group). After fatigue loading was applied using a chewing simulator, fracture resistance was measured by a universal testing machine. The fracture patterns were analyzed and the fractured surfaces were observed by scanning electron microscopy. After cyclic loading, none of the dentures showed cracks or fractures. During fracture resistance testing, all unreinforced dentures experienced complete fracture. The mesh-reinforced dentures primarily showed posterior framework fracture. Deformation of the all-metal framework caused the metal mesh-reinforced denture to exhibit the highest fracture resistance, followed by the glass fiber mesh-reinforced denture ( P <.05) and the control group ( P <.05). The glass fiber mesh-reinforced denture primarily maintained its original shape with unbroken fibers. River line pattern of the control group, dimples and interdendritic fractures of the metal mesh group, and radial fracture lines of the glass fiber group were observed on the fractured surfaces. The glass fiber mesh-reinforced denture exhibits a fracture resistance higher than that of the unreinforced denture, but lower than that of the metal mesh-reinforced denture because of the deformation of the metal mesh. The glass fiber mesh-reinforced denture maintains its shape even after fracture, indicating the possibility of easier repair.

Method of modifying a volume mesh using sheet insertion

DOEpatents

Borden, Michael J [Albuquerque, NM; Shepherd, Jason F [Albuquerque, NM

2006-08-29

A method and machine-readable medium provide a technique to modify a hexahedral finite element volume mesh using dual generation and sheet insertion. After generating a dual of a volume stack (mesh), a predetermined algorithm may be followed to modify (refine) the volume mesh of hexahedral elements. The predetermined algorithm may include the steps of locating a sheet of hexahedral mesh elements, determining a plurality of hexahedral elements within the sheet to refine, shrinking the plurality of elements, and inserting a new sheet of hexahedral elements adjacently to modify the volume mesh. Additionally, another predetermined algorithm using mesh cutting may be followed to modify a volume mesh.

Predicting mesh density for adaptive modelling of the global atmosphere.

PubMed

Weller, Hilary

2009-11-28

The shallow water equations are solved using a mesh of polygons on the sphere, which adapts infrequently to the predicted future solution. Infrequent mesh adaptation reduces the cost of adaptation and load-balancing and will thus allow for more accurate mapping on adaptation. We simulate the growth of a barotropically unstable jet adapting the mesh every 12 h. Using an adaptation criterion based largely on the gradient of the vorticity leads to a mesh with around 20 per cent of the cells of a uniform mesh that gives equivalent results. This is a similar proportion to previous studies of the same test case with mesh adaptation every 1-20 min. The prediction of the mesh density involves solving the shallow water equations on a coarse mesh in advance of the locally refined mesh in order to estimate where features requiring higher resolution will grow, decay or move to. The adaptation criterion consists of two parts: that resolved on the coarse mesh, and that which is not resolved and so is passively advected on the coarse mesh. This combination leads to a balance between resolving features controlled by the large-scale dynamics and maintaining fine-scale features.

Using clustering and a modified classification algorithm for automatic text summarization

NASA Astrophysics Data System (ADS)

Aries, Abdelkrime; Oufaida, Houda; Nouali, Omar

2013-01-01

In this paper we describe a modified classification method destined for extractive summarization purpose. The classification in this method doesn't need a learning corpus; it uses the input text to do that. First, we cluster the document sentences to exploit the diversity of topics, then we use a learning algorithm (here we used Naive Bayes) on each cluster considering it as a class. After obtaining the classification model, we calculate the score of a sentence in each class, using a scoring model derived from classification algorithm. These scores are used, then, to reorder the sentences and extract the first ones as the output summary. We conducted some experiments using a corpus of scientific papers, and we have compared our results to another summarization system called UNIS.1 Also, we experiment the impact of clustering threshold tuning, on the resulted summary, as well as the impact of adding more features to the classifier. We found that this method is interesting, and gives good performance, and the addition of new features (which is simple using this method) can improve summary's accuracy.

MeSH Now: automatic MeSH indexing at PubMed scale via learning to rank.

PubMed

Mao, Yuqing; Lu, Zhiyong

2017-04-17

MeSH indexing is the task of assigning relevant MeSH terms based on a manual reading of scholarly publications by human indexers. The task is highly important for improving literature retrieval and many other scientific investigations in biomedical research. Unfortunately, given its manual nature, the process of MeSH indexing is both time-consuming (new articles are not immediately indexed until 2 or 3 months later) and costly (approximately ten dollars per article). In response, automatic indexing by computers has been previously proposed and attempted but remains challenging. In order to advance the state of the art in automatic MeSH indexing, a community-wide shared task called BioASQ was recently organized. We propose MeSH Now, an integrated approach that first uses multiple strategies to generate a combined list of candidate MeSH terms for a target article. Through a novel learning-to-rank framework, MeSH Now then ranks the list of candidate terms based on their relevance to the target article. Finally, MeSH Now selects the highest-ranked MeSH terms via a post-processing module. We assessed MeSH Now on two separate benchmarking datasets using traditional precision, recall and F 1 -score metrics. In both evaluations, MeSH Now consistently achieved over 0.60 in F-score, ranging from 0.610 to 0.612. Furthermore, additional experiments show that MeSH Now can be optimized by parallel computing in order to process MEDLINE documents on a large scale. We conclude that MeSH Now is a robust approach with state-of-the-art performance for automatic MeSH indexing and that MeSH Now is capable of processing PubMed scale documents within a reasonable time frame. http://www.ncbi.nlm.nih.gov/CBBresearch/Lu/Demo/MeSHNow/ .

Effect of particle size on mixing degree in dispensation.

PubMed

Nakamura, Hitoshi; Yanagihara, Yoshitsugu; Sekiguchi, Hiroko; Ohtani, Michiteru; Kariya, Satoru; Uchino, Katsuyoshi; Suzuki, Hiroshi; Iga, Tatsuji

2004-03-01

By using lactose colored with erythrocin, we examined the effect of particle size on mixing degree during the preparation of triturations with a mortar and pestle. We used powders with different distributions of particle sizes, i.e., powder that passed through 32-mesh but was trapped on a 42-mesh sieve (32/42-mesh powder), powder that passed through a 42-mesh sieve but was trapped on a 60-mesh sieve (42/60-mesh powder), powder that passed through a 60-mesh sieve but was trapped on a 100-mesh sieve (60/100-mesh powder), and powder that passes through a 100-mesh sieve (> 100-mesh powder). The mixing degree of colored powder and non-colored powder whose distribution of particle sizes was the same as that of the colored powder was excellent. The coefficient of variation (CV) value of the mixing degree was 6.08% after 40 rotations when colored powder was mixed with non-colored powder that both passed through a 100-mesh sieve. The CV value of the mixing degree was low in the case of mixing of colored and non-colored powders with different particle size distributions. After mixing, about 50% of 42/60-mesh powder had become smaller particles, whereas the distribution of particle sizes was not influenced by the mixing of 60/100-mesh powder. It was suggested that the mixing degree is affected by distribution of particle sizes. It may be important to determine the mixing degrees for drugs with narrow therapeutic ranges.

An efficient and robust 3D mesh compression based on 3D watermarking and wavelet transform

NASA Astrophysics Data System (ADS)

Zagrouba, Ezzeddine; Ben Jabra, Saoussen; Didi, Yosra

2011-06-01

The compression and watermarking of 3D meshes are very important in many areas of activity including digital cinematography, virtual reality as well as CAD design. However, most studies on 3D watermarking and 3D compression are done independently. To verify a good trade-off between protection and a fast transfer of 3D meshes, this paper proposes a new approach which combines 3D mesh compression with mesh watermarking. This combination is based on a wavelet transformation. In fact, the used compression method is decomposed to two stages: geometric encoding and topologic encoding. The proposed approach consists to insert a signature between these two stages. First, the wavelet transformation is applied to the original mesh to obtain two components: wavelets coefficients and a coarse mesh. Then, the geometric encoding is done on these two components. The obtained coarse mesh will be marked using a robust mesh watermarking scheme. This insertion into coarse mesh allows obtaining high robustness to several attacks. Finally, the topologic encoding is applied to the marked coarse mesh to obtain the compressed mesh. The combination of compression and watermarking permits to detect the presence of signature after a compression of the marked mesh. In plus, it allows transferring protected 3D meshes with the minimum size. The experiments and evaluations show that the proposed approach presents efficient results in terms of compression gain, invisibility and robustness of the signature against of many attacks.

A New Method for Measuring Text Similarity in Learning Management Systems Using WordNet

ERIC Educational Resources Information Center

Alkhatib, Bassel; Alnahhas, Ammar; Albadawi, Firas

2014-01-01

As text sources are getting broader, measuring text similarity is becoming more compelling. Automatic text classification, search engines and auto answering systems are samples of applications that rely on text similarity. Learning management systems (LMS) are becoming more important since electronic media is getting more publicly available. As…

Does PRP enhance bone integration with grafts, graft substitutes, or implants? A systematic review

PubMed Central

2013-01-01

Background Several bone implants are applied in clinical practice, but none meets the requirements of an ideal implant. Platelet-rich plasma (PRP) is an easy and inexpensive way to obtain growth factors in physiologic proportions that might favour the regenerative process. The aim of this review is to analyse clinical studies in order to investigate the role of PRP in favouring bone integration of graft, graft substitutes, or implants, and to identify the materials for which the additional use of PRP might be associated with superior osseo- and soft tissues integration. Methods A search on PubMed database was performed considering the literature from 2000 to 2012, using the following string: ("Bone Substitutes"[Mesh] OR "Bone Transplantation"[Mesh] OR "Bone Regeneration"[Mesh] OR "Osseointegration"[Mesh]) AND ("Blood Platelets"[Mesh] OR "Platelet-Rich Plasma"[Mesh]). After abstracts screening, the full-texts of selected papers were analyzed and the papers found from the reference lists were also considered. The search focused on clinical applications documented in studies in the English language: levels of evidence included in the literature analysis were I, II and III. Results Literature analysis showed 83 papers that fulfilled the inclusion criteria: 26 randomized controlled trials (RCT), 14 comparative studies, 29 case series, and 14 case reports. Several implant materials were identified: 24 papers on autologous bone, 6 on freeze-dried bone allograft (FDBA), 16 on bovine porous bone mineral (BPBM), 9 on β-tricalcium phosphate (β-TCP), 4 on hydroxyapatite (HA), 2 on titanium (Ti), 1 on natural coral, 1 on collagen sponge, 1 on medical-grade calcium sulphate hemihydrate (MGCSH), 1 on bioactive glass (BG) and 18 on a combination of biomaterials. Only 4 papers were related to the orthopaedic field, whereas the majority belonged to clinical applications in oral/maxillofacial surgery. Conclusions The systematic research showed a growing interest in this approach for bone implant integration, with an increasing number of studies published over time. However, knowledge on this topic is still preliminary, with the presence mainly of low quality studies. Many aspects still have to be understood, such as the biomaterials that can benefit most from PRP and the best protocol for PRP both for production and application. PMID:24261343

BioCreative V CDR task corpus: a resource for chemical disease relation extraction.

PubMed

Li, Jiao; Sun, Yueping; Johnson, Robin J; Sciaky, Daniela; Wei, Chih-Hsuan; Leaman, Robert; Davis, Allan Peter; Mattingly, Carolyn J; Wiegers, Thomas C; Lu, Zhiyong

2016-01-01

Community-run, formal evaluations and manually annotated text corpora are critically important for advancing biomedical text-mining research. Recently in BioCreative V, a new challenge was organized for the tasks of disease named entity recognition (DNER) and chemical-induced disease (CID) relation extraction. Given the nature of both tasks, a test collection is required to contain both disease/chemical annotations and relation annotations in the same set of articles. Despite previous efforts in biomedical corpus construction, none was found to be sufficient for the task. Thus, we developed our own corpus called BC5CDR during the challenge by inviting a team of Medical Subject Headings (MeSH) indexers for disease/chemical entity annotation and Comparative Toxicogenomics Database (CTD) curators for CID relation annotation. To ensure high annotation quality and productivity, detailed annotation guidelines and automatic annotation tools were provided. The resulting BC5CDR corpus consists of 1500 PubMed articles with 4409 annotated chemicals, 5818 diseases and 3116 chemical-disease interactions. Each entity annotation includes both the mention text spans and normalized concept identifiers, using MeSH as the controlled vocabulary. To ensure accuracy, the entities were first captured independently by two annotators followed by a consensus annotation: The average inter-annotator agreement (IAA) scores were 87.49% and 96.05% for the disease and chemicals, respectively, in the test set according to the Jaccard similarity coefficient. Our corpus was successfully used for the BioCreative V challenge tasks and should serve as a valuable resource for the text-mining research community.Database URL: http://www.biocreative.org/tasks/biocreative-v/track-3-cdr/. Published by Oxford University Press 2016. This work is written by US Government employees and is in the public domain in the United States.

EFFECTS OF ETHYLENE OXIDE RESTERILISATION AND IN-VITRO DEGRADATION ON MECHANICAL PROPERTIES OF PARTIALLY ABSORBABLE COMPOSITE HERNIA MESHES.

PubMed

Endogan, T; Ozyaylali, I; Kulacoglu, H; Serbetci, K; Kiyak, G; Hasirci, N

2013-06-01

Prosthetic mesh repair for abdominal wall hernias is widely used because of its technical simplicity and low hernia recurrence rates. The most commonly used material is pure polypropylene mesh, however newer composite materials are recommended by some centers because of their advantages. However, these meshes are more expensive than pure polypropylene meshes. Resterilisation of a pure polypropylene mesh has been shown to be quite safe, and many centers prefer slicing a large mesh into smaller pieces that suitable for hernia type or defect size. Nevertheless there is no data about the safety after resterilisation of the composite meshes. To search the effects of resterilisation and In vitro degradation in phosphate buffered saline solution on the physical structure and the mechanical properties of partially absorbable lightweigth meshes. Laboratory-based research. Two composite meshes were used in the study: One mesh is consisted of monofilament polypropylene and monofilament polyglecaprone--a copolymer of glycolide and epsilon (ε)-caprolactone--(Ultrapro®, 28 g/m2, Ethicon, Hamburg, Germany),andthe otherone consisted of multifilamentpolypropyleneandmultifilament polyglactine (Vypro II®, 30 g/m2,Ethicon, Hamburg, Germany). Two large meshes were cut into rectangular specimens sized 50x20 mm for mechanical testing and 20x20 mm for In vitro degradation experiments. Meshes were divided into control group with no resterilisation and gas resterilisation. Ethylene oxide gas sterilisation was performed at 55°C for 4.5 hours. In vitro degradation in 0.01 M phosphate buffered saline (PBS, pH 7.4) solution at 37 ± 1°C for 8 weeks was applied to one subgroup in each mesh group. Tensiometric measurements and scanning electron microscopyic evaluations were completed for control and resterilisation specimens. Regardless of resterilisation, when meshes were exposed to In vitro degradation, all mechanical parameters decreased significantly. Highest reduction in mechanical properties was observed for Ultrapro due to the degradation of absorbable polyglecaprone and polyglactin parts of these meshes. It was observed that resterilisation by ethylene oxide did not have significant difference on the degradation characteristics and almost similar physical structures were observed for resterilised and non-resterilised meshes. For Vypro II meshes, no significant mechanical difference was observedbetweenresterilised andnon-resterilised meshes after degradationwhile resterilised Ultrapro meshes exhibited stronger characteristics than non-resterilised counterparts, after degradation. Resterilisation with ethylene oxide did not affect the mechanical properties of partially absorbable composite meshes. No important surface changeswere observed in scanning electron microscopy after resterilisation.

Minimizing finite-volume discretization errors on polyhedral meshes

NASA Astrophysics Data System (ADS)

Mouly, Quentin; Evrard, Fabien; van Wachem, Berend; Denner, Fabian

2017-11-01

Tetrahedral meshes are widely used in CFD to simulate flows in and around complex geometries, as automatic generation tools now allow tetrahedral meshes to represent arbitrary domains in a relatively accessible manner. Polyhedral meshes, however, are an increasingly popular alternative. While tetrahedron have at most four neighbours, the higher number of neighbours per polyhedral cell leads to a more accurate evaluation of gradients, essential for the numerical resolution of PDEs. The use of polyhedral meshes, nonetheless, introduces discretization errors for finite-volume methods: skewness and non-orthogonality, which occur with all sorts of unstructured meshes, as well as errors due to non-planar faces, specific to polygonal faces with more than three vertices. Indeed, polyhedral mesh generation algorithms cannot, in general, guarantee to produce meshes free of non-planar faces. The presented work focuses on the quantification and optimization of discretization errors on polyhedral meshes in the context of finite-volume methods. A quasi-Newton method is employed to optimize the relevant mesh quality measures. Various meshes are optimized and CFD results of cases with known solutions are presented to assess the improvements the optimization approach can provide.

Anterior pelvic organ prolapse repair using synthetic mesh.

PubMed

Patel, Bhavin N; Lucioni, Alvaro; Kobashi, Kathleen C

2012-06-01

Since the U.S. Food and Drug Administration (FDA) statement on mesh in July of 2011, there has been controversy regarding synthetic mesh repairs for vaginal prolapse. In this article, we review the biochemical basis for the use of synthetic mesh in prolapse repair as well as clinical results of anterior compartment prolapse repair with synthetic mesh. Finally, we discuss the FDA warning regarding mesh.

Quality of pharmacy-specific Medical Subject Headings (MeSH) assignment in pharmacy journals indexed in MEDLINE.

PubMed

Minguet, Fernando; Salgado, Teresa M; van den Boogerd, Lucienne; Fernandez-Llimos, Fernando

2015-01-01

The Medical Subject Headings (MeSH) is the National Library of Medicine (NLM) controlled vocabulary for indexing articles. Inaccuracies in the MeSH thesaurus have been reported for several areas including pharmacy. To assess the quality of pharmacy-specific MeSH assignment to articles indexed in pharmacy journals. The 10 journals containing the highest number of articles published in 2012 indexed under the MeSH 'Pharmacists' were identified. All articles published over a 5-year period (2008-2012) in the 10 previously selected journals were retrieved from PubMed. MeSH terms used to index these articles were extracted and pharmacy-specific MeSH terms were identified. The frequency of use of pharmacy-specific MeSH terms was calculated across journals. A total of 6989 articles were retrieved from the 10 pharmacy journals, of which 328 (4.7%) were articles not fully indexed and therefore did not contain any MeSH terms assigned. Among the 6661 articles fully indexed, the mean number of MeSH terms was 10.1 (SD = 4.0), being 1.0 (SD = 1.3) considered as Major MeSH. Both values significantly varied across journals. The mean number of pharmacy-specific MeSH terms per article was 0.9 (SD = 1.2). A total of 3490 (52.4%) of the 6661 articles were indexed in pharmacy journals without a single pharmacy-specific MeSH. Of the total 67193 MeSH terms assigned to articles, on average 10.5% (SD = 13.9) were pharmacy-specific MeSH. A statistically significant different pattern of pharmacy-specific MeSH assignment was identified across journals (Kruskal-Wallis P < 0.001). The quality of assignment of the existing pharmacy-specific MeSH terms to articles indexed in pharmacy journals can be improved to further enhance evidence gathering in pharmacy. Over half of the articles published in the top-10 journals publishing pharmacy literature were indexed without a single pharmacy-specific MeSH. Copyright © 2015 Elsevier Inc. All rights reserved.

Tissue response to collagen containing polypropylene meshes in an ovine vaginal repair model.

PubMed

Darzi, Saeedeh; Urbankova, Iva; Su, Kai; White, Jacinta; Lo, Camden; Alexander, David; Werkmeister, Jerome A; Gargett, Caroline E; Deprest, Jan

2016-07-15

Pelvic Organ Prolapse (POP) is the herniation of pelvic organs into the vagina. Despite broad acceptance of mesh use in POP surgical repair, the complication rate is unacceptable. We hypothesized that collagen-containing polypropylene (PP) mesh types could modulate mesh-tissue integration and reduce long-term inflammation, thereby reducing mesh-associated complications. This study compared the long-term tissue response to an unmodified PP mesh and two collagen containing meshes in an ovine model which has similar pelvic anatomy and vaginal size to human. Three commercially available macroporous PP meshes, uncoated PP mesh (Avaulta Solo) (PP), the same textile PP mesh layered with a sheet of cross-linked porcine acellular matrix (Avaulta Plus) (PP-ACM) and a different yet also macroporous PP (Sofradim) mesh coated with solubilized atelocollagen (Ugytex) (PP-sCOL) were implanted in the ovine vagina and tissue explanted after 60 and 180days. The macrophage phenotype and response to implanted meshes, and vascularity were quantified by immunostaining and morphometry. We quantified changes in extracellular matrix composition biochemically and collagen organisation and percentage area around the interface of the mesh implants by Sirius Red birefringence and morphometry. PP-ACM induced a more sustained inflammatory response, indicated by similar CD45(+) leukocytes but reduced CD163(+) M2 macrophages at 60days (P<0.05). PP-sCOL increased Von Willebrand Factor (vWF)-immunoreactive vessel profiles after 60days. At the micro-molecular level, collagen birefringence quantification revealed significantly fewer mature collagen fibrils (red, thick fibrils) at the mesh-tissue interface than control tissue for all mesh types (P<0.001) but still significantly greater than the proportion of immature (green thin fibrils) at 60days (P<0.05). The proportion of mature collagen fibrils increased with time around the mesh filaments, particularly those containing collagen. The total collagen percent area at the mesh interface was greatest around the PP-ACM mesh at 60days (P<0.05). By 180days the total mature and immature collagen fibres at the interface of the mesh filaments resembled that of native tissue. In particular, these results suggest that both meshes containing collagen evoke different types of tissue responses at different times during the healing response yet both ultimately lead to physiological tissue formation approaching that of normal tissue. Pelvic organ prolapse (POP) is the descent of the pelvic organs to the vagina. POP affects more than 25% of all women and the lifetime risk of undergoing POP surgery is 19%. Although synthetic polypropylene (PP) meshes have improved the outcome of the surgical treatment for POP, there was an unacceptable rate of adverse events including mesh exposure and contracture. It is hypothesized that coating the PP meshes with collagen would provide a protective effect by preventing severe mesh adhesions to the wound, resulting in a better controlled initial inflammatory response, and diminished risk of exposure. In this study we assessed the effect of two collagen-containing PP meshes on the long-term vaginal tissue response using new techniques to quantify these tissue responses. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effect of boundary representation on viscous, separated flows in a discontinuous-Galerkin Navier-Stokes solver

NASA Astrophysics Data System (ADS)

Nelson, Daniel A.; Jacobs, Gustaaf B.; Kopriva, David A.

2016-08-01

The effect of curved-boundary representation on the physics of the separated flow over a NACA 65(1)-412 airfoil is thoroughly investigated. A method is presented to approximate curved boundaries with a high-order discontinuous-Galerkin spectral element method for the solution of the Navier-Stokes equations. Multiblock quadrilateral element meshes are constructed with the grid generation software GridPro. The boundary of a NACA 65(1)-412 airfoil, defined by a cubic natural spline, is piecewise-approximated by isoparametric polynomial interpolants that represent the edges of boundary-fitted elements. Direct numerical simulation of the airfoil is performed on a coarse mesh and fine mesh with polynomial orders ranging from four to twelve. The accuracy of the curve fitting is investigated by comparing the flows computed on curved-sided meshes with those given by straight-sided meshes. Straight-sided meshes yield irregular wakes, whereas curved-sided meshes produce a regular Karman street wake. Straight-sided meshes also produce lower lift and higher viscous drag as compared with curved-sided meshes. When the mesh is refined by reducing the sizes of the elements, the lift decrease and viscous drag increase are less pronounced. The differences in the aerodynamic performance between the straight-sided meshes and the curved-sided meshes are concluded to be the result of artificial surface roughness introduced by the piecewise-linear boundary approximation provided by the straight-sided meshes.

ImmunemiR - A Database of Prioritized Immune miRNA Disease Associations and its Interactome.

PubMed

Prabahar, Archana; Natarajan, Jeyakumar

2017-01-01

MicroRNAs are the key regulators of gene expression and their abnormal expression in the immune system may be associated with several human diseases such as inflammation, cancer and autoimmune diseases. Elucidation of miRNA disease association through the interactome will deepen the understanding of its disease mechanisms. A specialized database for immune miRNAs is highly desirable to demonstrate the immune miRNA disease associations in the interactome. miRNAs specific to immune related diseases were retrieved from curated databases such as HMDD, miR2disease and PubMed literature based on MeSH classification of immune system diseases. The additional data such as miRNA target genes, genes coding protein-protein interaction information were compiled from related resources. Further, miRNAs were prioritized to specific immune diseases using random walk ranking algorithm. In total 245 immune miRNAs associated with 92 OMIM disease categories were identified from external databases. The resultant data were compiled as ImmunemiR, a database of prioritized immune miRNA disease associations. This database provides both text based annotation information and network visualization of its interactome. To our knowledge, ImmunemiR is the first available database to provide a comprehensive repository of human immune disease associated miRNAs with network visualization options of its target genes, protein-protein interactions (PPI) and its disease associations. It is freely available at http://www.biominingbu.org/immunemir/. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Comparison of the fracture resistances of glass fiber mesh- and metal mesh-reinforced maxillary complete denture under dynamic fatigue loading

PubMed Central

2017-01-01

PURPOSE The aim of this study was to investigate the effect of reinforcing materials on the fracture resistances of glass fiber mesh- and Cr–Co metal mesh-reinforced maxillary complete dentures under fatigue loading. MATERIALS AND METHODS Glass fiber mesh- and Cr–Co mesh-reinforced maxillary complete dentures were fabricated using silicone molds and acrylic resin. A control group was prepared with no reinforcement (n = 15 per group). After fatigue loading was applied using a chewing simulator, fracture resistance was measured by a universal testing machine. The fracture patterns were analyzed and the fractured surfaces were observed by scanning electron microscopy. RESULTS After cyclic loading, none of the dentures showed cracks or fractures. During fracture resistance testing, all unreinforced dentures experienced complete fracture. The mesh-reinforced dentures primarily showed posterior framework fracture. Deformation of the all-metal framework caused the metal mesh-reinforced denture to exhibit the highest fracture resistance, followed by the glass fiber mesh-reinforced denture (P<.05) and the control group (P<.05). The glass fiber mesh-reinforced denture primarily maintained its original shape with unbroken fibers. River line pattern of the control group, dimples and interdendritic fractures of the metal mesh group, and radial fracture lines of the glass fiber group were observed on the fractured surfaces. CONCLUSION The glass fiber mesh-reinforced denture exhibits a fracture resistance higher than that of the unreinforced denture, but lower than that of the metal mesh-reinforced denture because of the deformation of the metal mesh. The glass fiber mesh-reinforced denture maintains its shape even after fracture, indicating the possibility of easier repair. PMID:28243388

Surface orientation effects on bending properties of surgical mesh are independent of tensile properties.

PubMed

Simon, David D; Andrews, Sharon M; Robinson-Zeigler, Rebecca; Valdes, Thelma; Woods, Terry O

2018-02-01

Current mechanical testing of surgical mesh focuses primarily on tensile properties even though implanted devices are not subjected to pure tensile loads. Our objective was to determine the flexural (bending) properties of surgical mesh and determine if they correlate with mesh tensile properties. The flexural rigidity values of 11 different surgical mesh designs were determined along three textile directions (machine, cross-machine, and 45° to machine; n = 5 for each) using ASTM D1388-14 while tracking surface orientation. Tensile testing was also performed on the same specimens using ASTM D882-12. Linear regressions were performed to compare mesh flexural rigidity to mesh thickness, areal mass density, filament diameter, ultimate tensile strength, and maximum extension. Of 33 mesh specimen groups, 30 had significant differences in flexural rigidity values when comparing surface orientations (top and bottom). Flexural rigidity and mesh tensile properties also varied with textile direction (machine and cross-machine). There was no strong correlation between the flexural and tensile properties, with mesh thickness having the best overall correlation with flexural rigidity. Currently, surface orientation is not indicated on marketed surgical mesh, and a single mesh may behave differently depending on the direction of loading. The lack of correlation between flexural stiffness and tensile properties indicates the need to examine mesh bending stiffness to provide a more comprehensive understanding of surgical mesh mechanical behaviors. Further investigation is needed to determine if these flexural properties result in the surgical mesh behaving mechanically different depending on implantation direction. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 854-862, 2018. © 2017 Wiley Periodicals, Inc.

A Proximal Straining Mesh Location Is Associated With De Novo Stress Urinary Incontinence After Transobturator Mesh Procedures.

PubMed

Huang, Wen-Chen; Yang, Jenn-Ming

2017-03-01

The purpose of this study was to explore the association between mesh location and de novo stress urinary incontinence (SUI) after transvaginal mesh procedures. We retrospectively analyzed a database of women who had received transvaginal mesh procedures for stage III or greater cystocele according to the Pelvic Organ Prolapse Quantification system. Only data for women who neither reported SUI preoperatively nor had received concomitant anti-incontinence surgery were included for analyses. The mesh location was investigated by sonography via the percentage of the urethra covered by mesh, defined as the number calculated by dividing the portion of the urethral length covered by mesh (the distance from the bladder neck to the point of the urethra, which was indicated by an imaginary line at the level of the lower [caudal] mesh end and perpendicular to the urethra) by the total urethral length (the distance from the bladder neck to the external urethral meatus) in the sagittal plane. The resting, straining, coughing, and squeezing mesh locations of women who did (n = 29) and did not (n = 54) report SUI at the 12-month follow-up were compared. At the 12-month follow-up, women who reported SUI had a significantly smaller straining percentage of the urethra covered by mesh (mean ± SD, 28.5% ± 9.6%) compared with continent women (35.2% ± 15.8%), indicating a more proximal straining mesh location. Sonography is useful in investigating the location of the transvaginal mesh. De novo SUI after transvaginal mesh procedures is associated with a more proximal straining mesh location. © 2017 by the American Institute of Ultrasound in Medicine.

Mesh Oriented datABase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tautges, Timothy J.

MOAB is a component for representing and evaluating mesh data. MOAB can store stuctured and unstructured mesh, consisting of elements in the finite element "zoo". The functional interface to MOAB is simple yet powerful, allowing the representation of many types of metadata commonly found on the mesh. MOAB is optimized for efficiency in space and time, based on access to mesh in chunks rather than through individual entities, while also versatile enough to support individual entity access. The MOAB data model consists of a mesh interface instance, mesh entities (vertices and elements), sets, and tags. Entities are addressed through handlesmore » rather than pointers, to allow the underlying representation of an entity to change without changing the handle to that entity. Sets are arbitrary groupings of mesh entities and other sets. Sets also support parent/child relationships as a relation distinct from sets containing other sets. The directed-graph provided by set parent/child relationships is useful for modeling topological relations from a geometric model or other metadata. Tags are named data which can be assigned to the mesh as a whole, individual entities, or sets. Tags are a mechanism for attaching data to individual entities and sets are a mechanism for describing relations between entities; the combination of these two mechanisms isa powerful yet simple interface for representing metadata or application-specific data. For example, sets and tags can be used together to describe geometric topology, boundary condition, and inter-processor interface groupings in a mesh. MOAB is used in several ways in various applications. MOAB serves as the underlying mesh data representation in the VERDE mesh verification code. MOAB can also be used as a mesh input mechanism, using mesh readers induded with MOAB, or as a t’anslator between mesh formats, using readers and writers included with MOAB.« less

Bioprosthetic Mesh in Abdominal Wall Reconstruction

PubMed Central

Baumann, Donald P.; Butler, Charles E.

2012-01-01

Mesh materials have undergone a considerable evolution over the last several decades. There has been enhancement of biomechanical properties, improvement in manufacturing processes, and development of antiadhesive laminate synthetic meshes. The evolution of bioprosthetic mesh materials has markedly changed our indications and methods for complex abdominal wall reconstruction. The authors review the optimal properties of bioprosthetic mesh materials, their evolution over time, and their indications for use. The techniques to optimize outcomes are described using bioprosthetic mesh for complex abdominal wall reconstruction. Bioprosthetic mesh materials clearly have certain advantages over other implantable mesh materials in select indications. Appropriate patient selection and surgical technique are critical to the successful use of bioprosthetic materials for abdominal wall repair. PMID:23372454

Integration of Mesh Optimization with 3D All-Hex Mesh Generation, LDRD Subcase 3504340000, Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

KNUPP,PATRICK; MITCHELL,SCOTT A.

1999-11-01

In an attempt to automatically produce high-quality all-hex meshes, we investigated a mesh improvement strategy: given an initial poor-quality all-hex mesh, we iteratively changed the element connectivity, adding and deleting elements and nodes, and optimized the node positions. We found a set of hex reconnection primitives. We improved the optimization algorithms so they can untangle a negative-Jacobian mesh, even considering Jacobians on the boundary, and subsequently optimize the condition number of elements in an untangled mesh. However, even after applying both the primitives and optimization we were unable to produce high-quality meshes in certain regions. Our experiences suggest that manymore » boundary configurations of quadrilaterals admit no hexahedral mesh with positive Jacobians, although we have no proof of this.« less

Update on Development of Mesh Generation Algorithms in MeshKit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jain, Rajeev; Vanderzee, Evan; Mahadevan, Vijay

2015-09-30

MeshKit uses a graph-based design for coding all its meshing algorithms, which includes the Reactor Geometry (and mesh) Generation (RGG) algorithms. This report highlights the developmental updates of all the algorithms, results and future work. Parallel versions of algorithms, documentation and performance results are reported. RGG GUI design was updated to incorporate new features requested by the users; boundary layer generation and parallel RGG support were added to the GUI. Key contributions to the release, upgrade and maintenance of other SIGMA1 libraries (CGM and MOAB) were made. Several fundamental meshing algorithms for creating a robust parallel meshing pipeline in MeshKitmore » are under development. Results and current status of automated, open-source and high quality nuclear reactor assembly mesh generation algorithms such as trimesher, quadmesher, interval matching and multi-sweeper are reported.« less

Surgical mesh for ventral incisional hernia repairs: Understanding mesh design

PubMed Central

Rastegarpour, Ali; Cheung, Michael; Vardhan, Madhurima; Ibrahim, Mohamed M; Butler, Charles E; Levinson, Howard

2016-01-01

Surgical mesh has become an indispensable tool in hernia repair to improve outcomes and reduce costs; however, efforts are constantly being undertaken in mesh development to overcome postoperative complications. Common complications include infection, pain, adhesions, mesh extrusion and hernia recurrence. Reducing the complications of mesh implantation is of utmost importance given that hernias occur in hundreds of thousands of patients per year in the United States. In the present review, the authors present the different types of hernia meshes, discuss the key properties of mesh design, and demonstrate how each design element affects performance and complications. The present article will provide a basis for surgeons to understand which mesh to choose for patient care and why, and will explain the important technological aspects that will continue to evolve over the ensuing years. PMID:27054138

Integrating a novel shape memory polymer into surgical meshes to improve device performance during laparoscopic hernia surgery

NASA Astrophysics Data System (ADS)

Zimkowski, Michael M.

About 600,000 hernia repair surgeries are performed each year. The use of laparoscopic minimally invasive techniques has become increasingly popular in these operations. Use of surgical mesh in hernia repair has shown lower recurrence rates compared to other repair methods. However in many procedures, placement of surgical mesh can be challenging and even complicate the procedure, potentially leading to lengthy operating times. Various techniques have been attempted to improve mesh placement, including use of specialized systems to orient the mesh into a specific shape, with limited success and acceptance. In this work, a programmed novel Shape Memory Polymer (SMP) was integrated into commercially available polyester surgical meshes to add automatic unrolling and tissue conforming functionalities, while preserving the intrinsic structural properties of the original surgical mesh. Tensile testing and Dynamic Mechanical Analysis was performed on four different SMP formulas to identify appropriate mechanical properties for surgical mesh integration. In vitro testing involved monitoring the time required for a modified surgical mesh to deploy in a 37°C water bath. An acute porcine model was used to test the in vivo unrolling of SMP integrated surgical meshes. The SMP-integrated surgical meshes produced an automated, temperature activated, controlled deployment of surgical mesh on the order of several seconds, via laparoscopy in the animal model. A 30 day chronic rat model was used to test initial in vivo subcutaneous biocompatibility. To produce large more clinical relevant sizes of mesh, a mold was developed to facilitate manufacturing of SMP-integrated surgical mesh. The mold is capable of manufacturing mesh up to 361 cm2, which is believed to accommodate the majority of clinical cases. Results indicate surgical mesh modified with SMP is capable of laparoscopic deployment in vivo, activated by body temperature, and possesses the necessary strength and biocompatibility to function as suitable ventral hernia repair mesh, while offering a reduction in surgical operating time and improving mesh placement characteristics. Future work will include ball-burst tests similar to ASTM D3787-07, direct surgeon feedback studies, and a 30 day chronic porcine model to evaluate the SMP surgical mesh in a realistic hernia repair environment, using laparoscopic techniques for typical ventral hernia repair.

Meshes optimized for discrete exterior calculus (DEC).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mousley, Sarah C.; Deakin, Michael; Knupp, Patrick

We study the optimization of an energy function used by the meshing community to measure and improve mesh quality. This energy is non-traditional because it is dependent on both the primal triangulation and its dual Voronoi (power) diagram. The energy is a measure of the mesh's quality for usage in Discrete Exterior Calculus (DEC), a method for numerically solving PDEs. In DEC, the PDE domain is triangulated and this mesh is used to obtain discrete approximations of the continuous operators in the PDE. The energy of a mesh gives an upper bound on the error of the discrete diagonal approximationmore » of the Hodge star operator. In practice, one begins with an initial mesh and then makes adjustments to produce a mesh of lower energy. However, we have discovered several shortcomings in directly optimizing this energy, e.g. its non-convexity, and we show that the search for an optimized mesh may lead to mesh inversion (malformed triangles). We propose a new energy function to address some of these issues.« less

Determination of Proper Timing for the Placement of Intra-Abdominal Mesh after Incidental Enterotomy in a Rodent Model (Rattus norvegicus).

PubMed

Muir, Kathryn B; Smoot, Charles P; Viera, Jennifer L; Sirkin, Maxwell R; Yoon, Brian; Bader, Julia; Smiley, Rebecca; Holt, Danielle; Hofmann, Luke J

2018-04-01

Controversy exists regarding the appropriate timing for placement of permanent intra-abdominal mesh after inadvertent enterotomy during elective hernia repair. The aim of this study was to examine mesh placement at variable postoperative periods and the subsequent risk of infection. Fifty rodents were divided into five groups. Groups one to four underwent laparotomy, enterotomy, and repair. Physiomesh® was placed at the index operation one, three, or seven days postoperatively in Groups 1, 2, 3, and 4. Group 5 underwent mesh placement only. Necropsy with mesh harvest was performed seven days after placement. Cultures of mesh were obtained and Fisher's exact test was used to compare groups. Bacterial growth postsonication was identified in 30, 30, 50, and 90 per cent versus 20 per cent in controls. Compared with controls, there was significantly increased risk of mesh infection when it was placed seven days after enterotomy (P = 0.006). There was no significant difference in bacterial growth when mesh was placed at the time of enterotomy, one or three days later. The risk of bacterial contamination of permanent mesh placed immediately after inadvertent enterotomy during elective hernia repair is as safe as placing mesh at one or three days. Placing mesh at seven days significantly increased the risk of mesh contamination.

Grain Boundary Conformed Volumetric Mesh Generation from a Three-Dimensional Voxellated Polycrystalline Microstructure

NASA Astrophysics Data System (ADS)

Lee, Myeong-Jin; Jeon, Young-Ju; Son, Ga-Eun; Sung, Sihwa; Kim, Ju-Young; Han, Heung Nam; Cho, Soo Gyeong; Jung, Sang-Hyun; Lee, Sukbin

2018-07-01

We present a new comprehensive scheme for generating grain boundary conformed, volumetric mesh elements from a three-dimensional voxellated polycrystalline microstructure. From the voxellated image of a polycrystalline microstructure obtained from the Monte Carlo Potts model in the context of isotropic normal grain growth simulation, its grain boundary network is approximated as a curvature-maintained conformal triangular surface mesh using a set of in-house codes. In order to improve the surface mesh quality and to adjust mesh resolution, various re-meshing techniques in a commercial software are applied to the approximated grain boundary mesh. It is found that the aspect ratio, the minimum angle and the Jacobian value of the re-meshed surface triangular mesh are successfully improved. Using such an enhanced surface mesh, conformal volumetric tetrahedral elements of the polycrystalline microstructure are created using a commercial software, again. The resultant mesh seamlessly retains the short- and long-range curvature of grain boundaries and junctions as well as the realistic morphology of the grains inside the polycrystal. It is noted that the proposed scheme is the first to successfully generate three-dimensional mesh elements for polycrystals with high enough quality to be used for the microstructure-based finite element analysis, while the realistic characteristics of grain boundaries and grains are maintained from the corresponding voxellated microstructure image.

Grain Boundary Conformed Volumetric Mesh Generation from a Three-Dimensional Voxellated Polycrystalline Microstructure

NASA Astrophysics Data System (ADS)

Lee, Myeong-Jin; Jeon, Young-Ju; Son, Ga-Eun; Sung, Sihwa; Kim, Ju-Young; Han, Heung Nam; Cho, Soo Gyeong; Jung, Sang-Hyun; Lee, Sukbin

2018-03-01

We present a new comprehensive scheme for generating grain boundary conformed, volumetric mesh elements from a three-dimensional voxellated polycrystalline microstructure. From the voxellated image of a polycrystalline microstructure obtained from the Monte Carlo Potts model in the context of isotropic normal grain growth simulation, its grain boundary network is approximated as a curvature-maintained conformal triangular surface mesh using a set of in-house codes. In order to improve the surface mesh quality and to adjust mesh resolution, various re-meshing techniques in a commercial software are applied to the approximated grain boundary mesh. It is found that the aspect ratio, the minimum angle and the Jacobian value of the re-meshed surface triangular mesh are successfully improved. Using such an enhanced surface mesh, conformal volumetric tetrahedral elements of the polycrystalline microstructure are created using a commercial software, again. The resultant mesh seamlessly retains the short- and long-range curvature of grain boundaries and junctions as well as the realistic morphology of the grains inside the polycrystal. It is noted that the proposed scheme is the first to successfully generate three-dimensional mesh elements for polycrystals with high enough quality to be used for the microstructure-based finite element analysis, while the realistic characteristics of grain boundaries and grains are maintained from the corresponding voxellated microstructure image.

Automatic Mesh Generation of Hybrid Mesh on Valves in Multiple Positions in Feedline Systems

NASA Technical Reports Server (NTRS)

Ross, Douglass H.; Ito, Yasushi; Dorothy, Fredric W.; Shih, Alan M.; Peugeot, John

2010-01-01

Fluid flow simulations through a valve often require evaluation of the valve in multiple opening positions. A mesh has to be generated for the valve for each position and compounding. The problem is the fact that the valve is typically part of a larger feedline system. In this paper, we propose to develop a system to create meshes for feedline systems with parametrically controlled valve openings. Herein we outline two approaches to generate the meshes for a valve in a feedline system at multiple positions. There are two issues that must be addressed. The first is the creation of the mesh on the valve for multiple positions. The second is the generation of the mesh for the total feedline system including the valve. For generation of the mesh on the valve, we will describe the use of topology matching and mesh generation parameter transfer. For generation of the total feedline system, we will describe two solutions that we have implemented. In both cases the valve is treated as a component in the feedline system. In the first method the geometry of the valve in the feedline system is replaced with a valve at a different opening position. Geometry is created to connect the valve to the feedline system. Then topology for the valve is created and the portion of the topology for the valve is topology matched to the standard valve in a different position. The mesh generation parameters are transferred and then the volume mesh for the whole feedline system is generated. The second method enables the user to generate the volume mesh on the valve in multiple open positions external to the feedline system, to insert it into the volume mesh of the feedline system, and to reduce the amount of computer time required for mesh generation because only two small volume meshes connecting the valve to the feedline mesh need to be updated.

MRI Evaluation of an Elastic TPU Mesh under Pneumoperitoneum in IPOM Position in a Porcine Model.

PubMed

Lambertz, A; van den Hil, L C L; Ciritsis, A; Eickhoff, R; Kraemer, N A; Bouvy, N D; Müllen, A; Klinge, U; Neumann, U P; Klink, C D

2018-06-01

The frequency of laparoscopic approaches increased in hernia surgery over the past years. After mesh placement in IPOM position, the real extent of the meshes configurational changes after termination of pneumoperitoneum is still largely unknown. To prevent a later mesh folding it might be useful to place the mesh while it is kept under tension. Conventionally used meshes may lose their Effective Porosity under these conditions due to poor elastic properties. The aim of this study was to evaluate a newly developed elastic thermoplastic polyurethane (TPU) containing mesh that retains its Effective Porosity under mechanical strain in IPOM position in a porcine model. It was visualized under pneumoperitoneum using MRI in comparison to polyvinylidenefluoride (PVDF) meshes with similar structure. In each of ten minipigs, a mesh (TPU containing or native PVDF, 10 × 20 cm) was randomly placed in IPOM position at the center of the abdominal wall. After 8 weeks, six pigs underwent MRI evaluation with and without pneumoperitoneum to assess the visibility and elasticity of the mesh. Finally, pigs were euthanized and abdominal walls were explanted for histological and immunohistochemical assessment. The degree of adhesion formation was documented. Laparoscopic implantation of elastic TPU meshes in IPOM position was feasible and safe in a minipig model. Mesh position could be precisely visualized and assessed with and without pneumoperitoneum using MRI after 8 weeks. Elastic TPU meshes showed a significantly higher surface increase under pneumoperitoneum in comparison to PVDF. Immunohistochemically, the amount of CD45-positive cells was significantly lower and the Collagen I/III ratio was significantly higher in TPU meshes after 8 weeks. There were no differences regarding adhesion formation between study groups. The TPU mesh preserves its elastic properties in IPOM position in a porcine model after 8 weeks. Immunohistochemistry indicates superior biocompatibility regarding CD45-positive cells and Collagen I/III ratio in comparison to PVDF meshes with a similar structure.

Effects of ethylene oxide resterilization and in-vitro degradation on mechanical properties of partially absorbable composite hernia meshes.

PubMed

Endogan, T; Ozyaylali, I; Kulacoglu, H; Serbetci, K; Kiyak, G; Hasirci, N

2013-01-01

Prosthetic mesh repair for abdominal wall hernias is widely used because of its technical simplicity and low hernia recurrence rates. The most commonly used material is pure polypropylene mesh, although newer composite materials are recommended by some centers due to their advantages.However, these meshes are more expensive than pure polypropylene meshes. Resterilization of a pure polypropylene mesh has been shown to be quite safe, and many centers prefer slicing a large mesh into smaller pieces, suitable for any hernia type or defect size. Nevertheless there is no data about the safety after resterilization of the composite meshes. The present study was carried out to investigate the effects of resterilization and in vitro degradation in phosphate buffered saline solution on the physical structure and the mechanical properties of partially absorbable lightweight meshes. Two composite meshes were used in the study: One mesh consists of monofilament polypropylene and monofilament polyglecaprone -a copolymer of glycolide and epsilon(ε)- caprolactone - (Ultrapro®, 28 g m2, Ethicon, Hamburg,Germany), and the other one consisted of multifilament polypropylene and multifilament polyglactine (Vypro II®, 30g m2, Ethicon, Hamburg, Germany). Two large meshes were cut into rectangular specimens sized 50 x 20 mm for mechanical testing and 20 x 20 mm for in vitro degradation experiments.Meshes were divided into control group with no resterilization and gas resterilization. Ethylene oxide gas sterilization was performed at 55°C for 4.5 hours. In vitro degradation in 0.01M phosphate buffered saline (PBS, pH 7.4) solution at 37 ± 1°C for 8 weeks was applied to one subgroup in each mesh group. Tensiometric measurements and scanning electronmicroscopic evaluations were completed for control and resterilization specimens. Regardless of resterilization, when the meshes were exposed to in vitro degradation, all mechanical parameters decreased significantly. Highest reduction in mechanical properties was observed for Ultrapro due to the degradation of absorbable polyglecaprone and polyglactin parts of these meshes. It was observed that resterilization by ethylene oxide did not determine significant difference on the degradation characteristics and almost similar physical structures were observed for resterilized and non-resterilized meshes. For VyproII meshes, no significant mechanical difference was observed between resterilized and non-resterilized meshes after degradation while resterilized Ultrapro meshes exhibited stronger characteristics than non-resterilized counterparts, after degradation. Resterilization with ethylene oxide did not affect the mechanical properties of partially absorbable compositemeshes. No important surface changes were observed inscanning electron microscopy after resterilization. Celsius.

MOAB : a mesh-oriented database.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tautges, Timothy James; Ernst, Corey; Stimpson, Clint

A finite element mesh is used to decompose a continuous domain into a discretized representation. The finite element method solves PDEs on this mesh by modeling complex functions as a set of simple basis functions with coefficients at mesh vertices and prescribed continuity between elements. The mesh is one of the fundamental types of data linking the various tools in the FEA process (mesh generation, analysis, visualization, etc.). Thus, the representation of mesh data and operations on those data play a very important role in FEA-based simulations. MOAB is a component for representing and evaluating mesh data. MOAB can storemore » structured and unstructured mesh, consisting of elements in the finite element 'zoo'. The functional interface to MOAB is simple yet powerful, allowing the representation of many types of metadata commonly found on the mesh. MOAB is optimized for efficiency in space and time, based on access to mesh in chunks rather than through individual entities, while also versatile enough to support individual entity access. The MOAB data model consists of a mesh interface instance, mesh entities (vertices and elements), sets, and tags. Entities are addressed through handles rather than pointers, to allow the underlying representation of an entity to change without changing the handle to that entity. Sets are arbitrary groupings of mesh entities and other sets. Sets also support parent/child relationships as a relation distinct from sets containing other sets. The directed-graph provided by set parent/child relationships is useful for modeling topological relations from a geometric model or other metadata. Tags are named data which can be assigned to the mesh as a whole, individual entities, or sets. Tags are a mechanism for attaching data to individual entities and sets are a mechanism for describing relations between entities; the combination of these two mechanisms is a powerful yet simple interface for representing metadata or application-specific data. For example, sets and tags can be used together to describe geometric topology, boundary condition, and inter-processor interface groupings in a mesh. MOAB is used in several ways in various applications. MOAB serves as the underlying mesh data representation in the VERDE mesh verification code. MOAB can also be used as a mesh input mechanism, using mesh readers included with MOAB, or as a translator between mesh formats, using readers and writers included with MOAB. The remainder of this report is organized as follows. Section 2, 'Getting Started', provides a few simple examples of using MOAB to perform simple tasks on a mesh. Section 3 discusses the MOAB data model in more detail, including some aspects of the implementation. Section 4 summarizes the MOAB function API. Section 5 describes some of the tools included with MOAB, and the implementation of mesh readers/writers for MOAB. Section 6 contains a brief description of MOAB's relation to the TSTT mesh interface. Section 7 gives a conclusion and future plans for MOAB development. Section 8 gives references cited in this report. A reference description of the full MOAB API is contained in Section 9.« less

[Study on seed quality test and quality standard of Lonicera macranthoides].

PubMed

Zhang, Ying; Xu, Jin; Li, Long-Yun; Cui, Guang-Lin; She, Yue-Hui

2016-04-01

Referring to the rules for agricultural seed testing (GB/T 3543-1995) issued by China, the test of sampling, purity, thousand seed weight, moisture, viability, relative conductivity and germination rate had been studied for seed quality test methods of Lonicera macranthoides. The seed quality from 38 different collection areas was measured to establish quality classification standard by K-means clustering. The results showed that at least 7.5 g seeds should be sampled, and passed 20-mesh sieve for purity analysis.The 500-seed method used to measure thousand seed weight. The moisture was determined by crushed seeds dried in high temperature (130±2) ℃ for 3 h.The viability determined by 25 ℃ 0.1% TTC stained 5h in dark. 1.0 g seeds soaked in 50 ml ultra pure water in 25 ℃ for 12 hours to determine the relative conductivity. The seed by 4 ℃stratification for 80 days were cultured on paper at 15 ℃. Quality of the seeds from different areas was divided into three grades. The primary seed quality classification standard was established.The I grade and II grade were recommend use in production. Copyright© by the Chinese Pharmaceutical Association.

Automating document classification for the Immune Epitope Database

PubMed Central

Wang, Peng; Morgan, Alexander A; Zhang, Qing; Sette, Alessandro; Peters, Bjoern

2007-01-01

Background The Immune Epitope Database contains information on immune epitopes curated manually from the scientific literature. Like similar projects in other knowledge domains, significant effort is spent on identifying which articles are relevant for this purpose. Results We here report our experience in automating this process using Naïve Bayes classifiers trained on 20,910 abstracts classified by domain experts. Improvements on the basic classifier performance were made by a) utilizing information stored in PubMed beyond the abstract itself b) applying standard feature selection criteria and c) extracting domain specific feature patterns that e.g. identify peptides sequences. We have implemented the classifier into the curation process determining if abstracts are clearly relevant, clearly irrelevant, or if no certain classification can be made, in which case the abstracts are manually classified. Testing this classification scheme on an independent dataset, we achieve 95% sensitivity and specificity in the 51.1% of abstracts that were automatically classified. Conclusion By implementing text classification, we have sped up the reference selection process without sacrificing sensitivity or specificity of the human expert classification. This study provides both practical recommendations for users of text classification tools, as well as a large dataset which can serve as a benchmark for tool developers. PMID:17655769

High-fidelity meshes from tissue samples for diffusion MRI simulations.

PubMed

Panagiotaki, Eleftheria; Hall, Matt G; Zhang, Hui; Siow, Bernard; Lythgoe, Mark F; Alexander, Daniel C

2010-01-01

This paper presents a method for constructing detailed geometric models of tissue microstructure for synthesizing realistic diffusion MRI data. We construct three-dimensional mesh models from confocal microscopy image stacks using the marching cubes algorithm. Random-walk simulations within the resulting meshes provide synthetic diffusion MRI measurements. Experiments optimise simulation parameters and complexity of the meshes to achieve accuracy and reproducibility while minimizing computation time. Finally we assess the quality of the synthesized data from the mesh models by comparison with scanner data as well as synthetic data from simple geometric models and simplified meshes that vary only in two dimensions. The results support the extra complexity of the three-dimensional mesh compared to simpler models although sensitivity to the mesh resolution is quite robust.

Hybrid seine for full fish community collections

USGS Publications Warehouse

McKenna, James E.; Waldt, Emily M.; Abbett, Ross; David, Anthony; Snyder, James

2013-01-01

Seines are simple and effective fish collection gears, but the net mesh size influences how well the catch represents the fish communities. We designed and tested a hybrid seine with a dual-mesh bag (1/4″ and 1/8″) and compared the fish assemblage collected by each mesh. The fine-mesh net retained three times as many fish and collected more species (as many as eight), including representatives of several rare species, than did the coarser mesh. The dual-mesh bag permitted us to compare both sizes and species retained by each layer and to develop species-specific abundance correction factors, which allowed comparison of catches with the coarse-mesh seine used for earlier collections. The results indicate that a hybrid seine with coarse-mesh wings and a fine-mesh bag would enhance future studies of fish communities, especially when small-bodied fishes or early life stages are the research focus.

Reversible switch between underwater superaerophilicity and superaerophobicity on the superhydrophobic nanowire-haired mesh for controlling underwater bubble wettability

NASA Astrophysics Data System (ADS)

Shan, Chao; Yong, Jiale; Yang, Qing; Chen, Feng; Huo, Jinglan; Zhuang, Jian; Jiang, Zhuangde; Hou, Xun

2018-04-01

Controlling the underwater bubble wettability on a solid surface is of great research significance. In this letter, a simple method to achieve reversible switch between underwater superaerophilicity and underwater superaerophobicity on a superhydrophobic nanowire-haired mesh by alternately vacuumizing treatment in water and drying in air is reported. Such reversible switch endows the as-prepared mesh with many functional applications in controlling bubble's behavior on a solid substrate. The underwater superaerophilic mesh is able to absorb/capture bubbles in water, while the superaerophobic mesh has great anti-bubble ability. The reversible switch between underwater superaerophilicity and superaerophobicity can selectively allow bubbles to go through the resultant mesh; that is, bubbles can pass through the underwater superaerophilic mesh while are fully intercepted by the underwater superaerophobic mesh in a water medium. We believe these meshes will have important applications in removing or capturing underwater bubbles/gas.

Metamesh, Version 1.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Staley, Martin

Metamesh is a general-purpose C++ library for creating "mesh" data structures from smaller parts. That is, rather than providing a traditional "mesh format," as many libraries do, or a GUI for building meshes, Metamesh provides tools by which the mesh structures themselves can be built. Consider that a mesh in up to three dimensions can contain nodes (0d entities), edges (1d), faces (2d), and cells (3d). Edges are typically defined from two nodes. Faces can be defined from nodes or edges; and cells from nodes, edges, or faces. Someone might also wish to allow for general faces or cells, ormore » for only a specific variant - say, triangular faces and tetrahedral cells. Moreover, a mesh can have the same or a lesser dimension than that of its enclosing space. In 3d, say, one could have a full 3d mesh, a 2d "sheet" mesh without cells, a 1d "string" mesh with neither faces nor cells, or even a 1d "point cloud." And, aside from the mesh structure itself, additional data might be wanted: velocities at nodes, say, or fluxes across faces, or an average density in each cell. Metamesh supports all of this, through C++ generics and template metaprogramming techniques. Users fit Metamesh constructs together to define a mesh layout, and Metamesh then automatically provides the newly constructed mesh with functionality. Metamesh also provides facilities for spinning, extruding, visualizing, and performing I/O of whatever meshes a user builds.« less

Anisotropic evaluation of synthetic surgical meshes.

PubMed

Saberski, E R; Orenstein, S B; Novitsky, Y W

2011-02-01

The material properties of meshes used in hernia repair contribute to the overall mechanical behavior of the repair. The anisotropic potential of synthetic meshes, representing a difference in material properties (e.g., elasticity) in different material axes, is not well defined to date. Haphazard orientation of anisotropic mesh material can contribute to inconsistent surgical outcomes. We aimed to characterize and compare anisotropic properties of commonly used synthetic meshes. Six different polypropylene (Trelex(®), ProLite™, Ultrapro™), polyester (Parietex™), and PTFE-based (Dualmesh(®), Infinit) synthetic meshes were selected. Longitudinal and transverse axes were defined for each mesh, and samples were cut in each axis orientation. Samples underwent uniaxial tensile testing, from which the elastic modulus (E) in each axis was determined. The degree of anisotropy (λ) was calculated as a logarithmic expression of the ratio between the elastic modulus in each axis. Five of six meshes displayed significant anisotropic behavior. Ultrapro™ and Infinit exhibited approximately 12- and 20-fold differences between perpendicular axes, respectively. Trelex(®), ProLite™, and Parietex™ were 2.3-2.4 times. Dualmesh(®) was the least anisotropic mesh, without marked difference between the axes. Anisotropy of synthetic meshes has been underappreciated. In this study, we found striking differences between elastic properties of perpendicular axes for most commonly used synthetic meshes. Indiscriminate orientation of anisotropic mesh may adversely affect hernia repairs. Proper labeling of all implants by manufacturers should be mandatory. Understanding the specific anisotropic behavior of synthetic meshes should allow surgeons to employ rational implant orientation to maximize outcomes of hernia repair.

Use and risks of surgical mesh for pelvic organ prolapse surgery in women in New York state: population based cohort study.

PubMed

Chughtai, Bilal; Mao, Jialin; Buck, Jessica; Kaplan, Steven; Sedrakyan, Art

2015-06-02

To assess the use of mesh in pelvic organ prolapse surgery, and compare short term outcomes between procedures using and not using mesh. All inclusive, population based cohort study. Statewide surgical care captured in the New York Statewide Planning and Research Cooperative System. Women who underwent prolapse repair procedures in New York state from 2008 to 2011. 90 day safety events and reinterventions within one year, after propensity score matching. Categorical, time to event, and subgroup analyses (<65 and ≥ 65 year age groups) were conducted. Of 27,991 patients in total, 7338 and 20, 653 underwent prolapse repair procedures with and without mesh, respectively. Mesh use increased by 44.7%, from 1461 procedures in 2008 to 2114 procedures in 2011. Most patients in the cohort were younger than 65 years (62.3% (n=17,424/27, 991)). However, more patients were aged 65 years and older in the mesh group than in the non-mesh group (44.3% (n=3249) v 35.4% (n=7318)). Complications after surgery were not common, irrespective of the use or non-use of mesh. After propensity score matching, patients who received the surgery with mesh had a higher chance of having a reintervention within one year (mesh 3.3% v no mesh 2.2%, hazard ratio 1.47 (95% confidence interval 1.21 to 1.79)) and were more likely to have urinary retention within 90 days (mesh 7.5% v no mesh 5.6%, risk ratio 1.33 (95% confidence interval 1.18 to 1.51)), compared with those who received surgery without mesh. In subgroup analyses based on age, mesh use was associated with an increased risk of reintervention within one year in patients under age 65 years, and increased risk of urinary retention in patients aged 65 years and over. Despite multiple warnings released by the US Food and Drug Administration since 2008, use of mesh in pelvic organ prolapse surgery continues to grow. In this statewide comprehensive study, mesh procedures were associated with an increased risk of reinterventions within one year and urinary retention after surgery. © Chughtai et al 2015.

Vaccine adverse event text mining system for extracting features from vaccine safety reports.

PubMed

Botsis, Taxiarchis; Buttolph, Thomas; Nguyen, Michael D; Winiecki, Scott; Woo, Emily Jane; Ball, Robert

2012-01-01

To develop and evaluate a text mining system for extracting key clinical features from vaccine adverse event reporting system (VAERS) narratives to aid in the automated review of adverse event reports. Based upon clinical significance to VAERS reviewing physicians, we defined the primary (diagnosis and cause of death) and secondary features (eg, symptoms) for extraction. We built a novel vaccine adverse event text mining (VaeTM) system based on a semantic text mining strategy. The performance of VaeTM was evaluated using a total of 300 VAERS reports in three sequential evaluations of 100 reports each. Moreover, we evaluated the VaeTM contribution to case classification; an information retrieval-based approach was used for the identification of anaphylaxis cases in a set of reports and was compared with two other methods: a dedicated text classifier and an online tool. The performance metrics of VaeTM were text mining metrics: recall, precision and F-measure. We also conducted a qualitative difference analysis and calculated sensitivity and specificity for classification of anaphylaxis cases based on the above three approaches. VaeTM performed best in extracting diagnosis, second level diagnosis, drug, vaccine, and lot number features (lenient F-measure in the third evaluation: 0.897, 0.817, 0.858, 0.874, and 0.914, respectively). In terms of case classification, high sensitivity was achieved (83.1%); this was equal and better compared to the text classifier (83.1%) and the online tool (40.7%), respectively. Our VaeTM implementation of a semantic text mining strategy shows promise in providing accurate and efficient extraction of key features from VAERS narratives.

Computer assisted detection of abnormal airway variation in CT scans related to paediatric tuberculosis.

PubMed

Irving, Benjamin J; Goussard, Pierre; Andronikou, Savvas; Gie, Robert; Douglas, Tania S; Todd-Pokropek, Andrew; Taylor, Paul

2014-10-01

Airway deformation and stenosis can be key signs of pathology such as lymphadenopathy. This study presents a local airway point distribution model (LA-PDM) to automatically analyse regions of the airway tree in CT scans and identify abnormal airway deformation. In our method, the airway tree is segmented and the centreline identified from each chest CT scan. Thin-plate splines, along with a local mesh alignment method for tubular meshes, are used to register the airways and develop point distribution models (PDM). Each PDM is then used to analyse and classify local regions of the airway. This LA-PDM method was developed using 89 training cases and evaluated on a 90 CT test set, where each set includes paediatric tuberculosis (TB) cases (with airway involvement) and non-TB cases (without airway involvement). The LA-PDM was able to accurately distinguish cases with airway involvement with an AUC of the ROC classification (and 95% confidence interval) of 0.87 (0.77-0.94) for the Trachea-LMB-RMB region and 0.81 (0.68-0.90) for the RMB-RUL-BI region - outperforming a comparison method based on airway cross-sectional features. This has the potential to assist and improve airway analysis from CT scans by detecting involved airways and visualising affected airway regions. Copyright © 2014 Elsevier B.V. All rights reserved.

An electrostatic Particle-In-Cell code on multi-block structured meshes

NASA Astrophysics Data System (ADS)

Meierbachtol, Collin S.; Svyatskiy, Daniil; Delzanno, Gian Luca; Vernon, Louis J.; Moulton, J. David

2017-12-01

We present an electrostatic Particle-In-Cell (PIC) code on multi-block, locally structured, curvilinear meshes called Curvilinear PIC (CPIC). Multi-block meshes are essential to capture complex geometries accurately and with good mesh quality, something that would not be possible with single-block structured meshes that are often used in PIC and for which CPIC was initially developed. Despite the structured nature of the individual blocks, multi-block meshes resemble unstructured meshes in a global sense and introduce several new challenges, such as the presence of discontinuities in the mesh properties and coordinate orientation changes across adjacent blocks, and polyjunction points where an arbitrary number of blocks meet. In CPIC, these challenges have been met by an approach that features: (1) a curvilinear formulation of the PIC method: each mesh block is mapped from the physical space, where the mesh is curvilinear and arbitrarily distorted, to the logical space, where the mesh is uniform and Cartesian on the unit cube; (2) a mimetic discretization of Poisson's equation suitable for multi-block meshes; and (3) a hybrid (logical-space position/physical-space velocity), asynchronous particle mover that mitigates the performance degradation created by the necessity to track particles as they move across blocks. The numerical accuracy of CPIC was verified using two standard plasma-material interaction tests, which demonstrate good agreement with the corresponding analytic solutions. Compared to PIC codes on unstructured meshes, which have also been used for their flexibility in handling complex geometries but whose performance suffers from issues associated with data locality and indirect data access patterns, PIC codes on multi-block structured meshes may offer the best compromise for capturing complex geometries while also maintaining solution accuracy and computational efficiency.

An electrostatic Particle-In-Cell code on multi-block structured meshes

DOE PAGES

Meierbachtol, Collin S.; Svyatskiy, Daniil; Delzanno, Gian Luca; ...

2017-09-14

We present an electrostatic Particle-In-Cell (PIC) code on multi-block, locally structured, curvilinear meshes called Curvilinear PIC (CPIC). Multi-block meshes are essential to capture complex geometries accurately and with good mesh quality, something that would not be possible with single-block structured meshes that are often used in PIC and for which CPIC was initially developed. In spite of the structured nature of the individual blocks, multi-block meshes resemble unstructured meshes in a global sense and introduce several new challenges, such as the presence of discontinuities in the mesh properties and coordinate orientation changes across adjacent blocks, and polyjunction points where anmore » arbitrary number of blocks meet. In CPIC, these challenges have been met by an approach that features: (1) a curvilinear formulation of the PIC method: each mesh block is mapped from the physical space, where the mesh is curvilinear and arbitrarily distorted, to the logical space, where the mesh is uniform and Cartesian on the unit cube; (2) a mimetic discretization of Poisson's equation suitable for multi-block meshes; and (3) a hybrid (logical-space position/physical-space velocity), asynchronous particle mover that mitigates the performance degradation created by the necessity to track particles as they move across blocks. The numerical accuracy of CPIC was verified using two standard plasma–material interaction tests, which demonstrate good agreement with the corresponding analytic solutions. And compared to PIC codes on unstructured meshes, which have also been used for their flexibility in handling complex geometries but whose performance suffers from issues associated with data locality and indirect data access patterns, PIC codes on multi-block structured meshes may offer the best compromise for capturing complex geometries while also maintaining solution accuracy and computational efficiency.« less

An electrostatic Particle-In-Cell code on multi-block structured meshes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meierbachtol, Collin S.; Svyatskiy, Daniil; Delzanno, Gian Luca

We present an electrostatic Particle-In-Cell (PIC) code on multi-block, locally structured, curvilinear meshes called Curvilinear PIC (CPIC). Multi-block meshes are essential to capture complex geometries accurately and with good mesh quality, something that would not be possible with single-block structured meshes that are often used in PIC and for which CPIC was initially developed. In spite of the structured nature of the individual blocks, multi-block meshes resemble unstructured meshes in a global sense and introduce several new challenges, such as the presence of discontinuities in the mesh properties and coordinate orientation changes across adjacent blocks, and polyjunction points where anmore » arbitrary number of blocks meet. In CPIC, these challenges have been met by an approach that features: (1) a curvilinear formulation of the PIC method: each mesh block is mapped from the physical space, where the mesh is curvilinear and arbitrarily distorted, to the logical space, where the mesh is uniform and Cartesian on the unit cube; (2) a mimetic discretization of Poisson's equation suitable for multi-block meshes; and (3) a hybrid (logical-space position/physical-space velocity), asynchronous particle mover that mitigates the performance degradation created by the necessity to track particles as they move across blocks. The numerical accuracy of CPIC was verified using two standard plasma–material interaction tests, which demonstrate good agreement with the corresponding analytic solutions. And compared to PIC codes on unstructured meshes, which have also been used for their flexibility in handling complex geometries but whose performance suffers from issues associated with data locality and indirect data access patterns, PIC codes on multi-block structured meshes may offer the best compromise for capturing complex geometries while also maintaining solution accuracy and computational efficiency.« less

Unstructured mesh generation and adaptivity

NASA Technical Reports Server (NTRS)

Mavriplis, D. J.

1995-01-01

An overview of current unstructured mesh generation and adaptivity techniques is given. Basic building blocks taken from the field of computational geometry are first described. Various practical mesh generation techniques based on these algorithms are then constructed and illustrated with examples. Issues of adaptive meshing and stretched mesh generation for anisotropic problems are treated in subsequent sections. The presentation is organized in an education manner, for readers familiar with computational fluid dynamics, wishing to learn more about current unstructured mesh techniques.

Mesh Intercomparisons of Fog Water Collected Yield Insight Into the Nature of Fog-Drip Collection Mechanisms

NASA Astrophysics Data System (ADS)

Fernandez, D.; Torregrosa, A.; Weiss-Penzias, P. S.; Oliphant, A. J.; Dodge, C.; Bowman, M.; Wilson, S.; Mairs, A. A.; Gravelle, M.; Barkley, T.

2016-12-01

At multiple sites across central CA, several passive fog water collectors have been deployed for the past 3 years. All of the sites employ standard Raschel polypropylene mesh as the fog collection medium and five of them also integrated a novel polypropylene mesh of German manufacture with a 3-dimensional internal structure. Additionally, six metal mesh manufactured by McMaster-Carr of various hole sizing were coated with a POSS-PEMA substance at the Massachusetts Institute of Technology and deployed in parallel with the Raschel mesh at six distinct locations. Finally, fluorine-free versions of the POSS-PEMA substance were generated by NBD Nanotechnology and coated on a much finer mesh substrate. Three of those and one control (uncoated mesh) were deployed at one of the fog collection sites for one season, along with a standard Raschel mesh. Preliminary results from one intercomparison from just one pair of mesh over two seasons seem to reveal a wind speed and also, possibly, a droplet-size dependence on the fog collection efficiency for the mesh. This study will continue to intercompare the various mesh in conjunction with the wind speed and direction data. If a collection efficiency dependence on mesh size or coating is confirmed, it may point to interesting and relevant mechanisms for fog droplet capture and collection hitherto unobserved in field conditions.

Mesh Algorithms for PDE with Sieve I: Mesh Distribution

DOE PAGES

Knepley, Matthew G.; Karpeev, Dmitry A.

2009-01-01

We have developed a new programming framework, called Sieve, to support parallel numerical partial differential equation(s) (PDE) algorithms operating over distributed meshes. We have also developed a reference implementation of Sieve in C++ as a library of generic algorithms operating on distributed containers conforming to the Sieve interface. Sieve makes instances of the incidence relation, or arrows, the conceptual first-class objects represented in the containers. Further, generic algorithms acting on this arrow container are systematically used to provide natural geometric operations on the topology and also, through duality, on the data. Finally, coverings and duality are used to encode notmore » only individual meshes, but all types of hierarchies underlying PDE data structures, including multigrid and mesh partitions. In order to demonstrate the usefulness of the framework, we show how the mesh partition data can be represented and manipulated using the same fundamental mechanisms used to represent meshes. We present the complete description of an algorithm to encode a mesh partition and then distribute a mesh, which is independent of the mesh dimension, element shape, or embedding. Moreover, data associated with the mesh can be similarly distributed with exactly the same algorithm. The use of a high level of abstraction within the Sieve leads to several benefits in terms of code reuse, simplicity, and extensibility. We discuss these benefits and compare our approach to other existing mesh libraries.« less

Mapping annotations with textual evidence using an scLDA model.

PubMed

Jin, Bo; Chen, Vicky; Chen, Lujia; Lu, Xinghua

2011-01-01

Most of the knowledge regarding genes and proteins is stored in biomedical literature as free text. Extracting information from complex biomedical texts demands techniques capable of inferring biological concepts from local text regions and mapping them to controlled vocabularies. To this end, we present a sentence-based correspondence latent Dirichlet allocation (scLDA) model which, when trained with a corpus of PubMed documents with known GO annotations, performs the following tasks: 1) learning major biological concepts from the corpus, 2) inferring the biological concepts existing within text regions (sentences), and 3) identifying the text regions in a document that provides evidence for the observed annotations. When applied to new gene-related documents, a trained scLDA model is capable of predicting GO annotations and identifying text regions as textual evidence supporting the predicted annotations. This study uses GO annotation data as a testbed; the approach can be generalized to other annotated data, such as MeSH and MEDLINE documents.

Adaptive moving mesh methods for simulating one-dimensional groundwater problems with sharp moving fronts

USGS Publications Warehouse

Huang, W.; Zheng, Lingyun; Zhan, X.

2002-01-01

Accurate modelling of groundwater flow and transport with sharp moving fronts often involves high computational cost, when a fixed/uniform mesh is used. In this paper, we investigate the modelling of groundwater problems using a particular adaptive mesh method called the moving mesh partial differential equation approach. With this approach, the mesh is dynamically relocated through a partial differential equation to capture the evolving sharp fronts with a relatively small number of grid points. The mesh movement and physical system modelling are realized by solving the mesh movement and physical partial differential equations alternately. The method is applied to the modelling of a range of groundwater problems, including advection dominated chemical transport and reaction, non-linear infiltration in soil, and the coupling of density dependent flow and transport. Numerical results demonstrate that sharp moving fronts can be accurately and efficiently captured by the moving mesh approach. Also addressed are important implementation strategies, e.g. the construction of the monitor function based on the interpolation error, control of mesh concentration, and two-layer mesh movement. Copyright ?? 2002 John Wiley and Sons, Ltd.

A novel method for pair-matching using three-dimensional digital models of bone: mesh-to-mesh value comparison.

PubMed

Karell, Mara A; Langstaff, Helen K; Halazonetis, Demetrios J; Minghetti, Caterina; Frelat, Mélanie; Kranioti, Elena F

2016-09-01

The commingling of human remains often hinders forensic/physical anthropologists during the identification process, as there are limited methods to accurately sort these remains. This study investigates a new method for pair-matching, a common individualization technique, which uses digital three-dimensional models of bone: mesh-to-mesh value comparison (MVC). The MVC method digitally compares the entire three-dimensional geometry of two bones at once to produce a single value to indicate their similarity. Two different versions of this method, one manual and the other automated, were created and then tested for how well they accurately pair-matched humeri. Each version was assessed using sensitivity and specificity. The manual mesh-to-mesh value comparison method was 100 % sensitive and 100 % specific. The automated mesh-to-mesh value comparison method was 95 % sensitive and 60 % specific. Our results indicate that the mesh-to-mesh value comparison method overall is a powerful new tool for accurately pair-matching commingled skeletal elements, although the automated version still needs improvement.

Geometric modeling of hepatic arteries in 3D ultrasound with unsupervised MRA fusion during liver interventions.

PubMed

Gérard, Maxime; Michaud, François; Bigot, Alexandre; Tang, An; Soulez, Gilles; Kadoury, Samuel

2017-06-01

Modulating the chemotherapy injection rate with regard to blood flow velocities in the tumor-feeding arteries during intra-arterial therapies may help improve liver tumor targeting while decreasing systemic exposure. These velocities can be obtained noninvasively using Doppler ultrasound (US). However, small vessels situated in the liver are difficult to identify and follow in US. We propose a multimodal fusion approach that non-rigidly registers a 3D geometric mesh model of the hepatic arteries obtained from preoperative MR angiography (MRA) acquisitions with intra-operative 3D US imaging. The proposed fusion tool integrates 3 imaging modalities: an arterial MRA, a portal phase MRA and an intra-operative 3D US. Preoperatively, the arterial phase MRA is used to generate a 3D model of the hepatic arteries, which is then non-rigidly co-registered with the portal phase MRA. Once the intra-operative 3D US is acquired, we register it with the portal MRA using a vessel-based rigid initialization followed by a non-rigid registration using an image-based metric based on linear correlation of linear combination. Using the combined non-rigid transformation matrices, the 3D mesh model is fused with the 3D US. 3D US and multi-phase MRA images acquired from 10 porcine models were used to test the performance of the proposed fusion tool. Unimodal registration of the MRA phases yielded a target registration error (TRE) of [Formula: see text] mm. Initial rigid alignment of the portal MRA and 3D US yielded a mean TRE of [Formula: see text] mm, which was significantly reduced to [Formula: see text] mm ([Formula: see text]) after affine image-based registration. The following deformable registration step allowed for further decrease of the mean TRE to [Formula: see text] mm. The proposed tool could facilitate visualization and localization of these vessels when using 3D US intra-operatively for either intravascular or percutaneous interventions to avoid vessel perforation.

Towards hybrid mesh generation for realistic design environments

NASA Astrophysics Data System (ADS)

McMorris, Harlan Tom

Two different techniques that allow hybrid mesh generation to be easily used in the design environment are presented. The purpose of this research is to allow for hybrid meshes to be used during the design process where the geometry is being varied. The first technique, modular hybrid mesh generation, allows for the replacement of portions of a geometry with a new design shape. The mesh is maintained for the portions of that have not changed during the design process. A new mesh is generated for the new part of the geometry and this piece is added to the existing mesh. The new mesh must match the remaining portions of the geometry plus the element sizes must match exactly across the interfaces. The second technique, hybrid mesh movement, is used when the basic geometry remains the same with only small variations to portions of the geometry. These small variations include changing the cross-section of a wing, twisting a blade or changing the length of some portion of the geometry. The mesh for the original geometry is moved onto the new geometry one step at a time beginning with the curves of the surface, continuing with the surface mesh geometry and ending with the interior points of the mesh. The validity of the hybrid mesh is maintained by applying corrections to the motion of the points. Finally, the quality of the new hybrid mesh is improved to ensure that the new mesh maintains the quality of the original hybrid mesh. Applications of both design techniques are applied to typical example cases from the fields of turbomachinery, aerospace and offshore technology. The example test cases demonstrate the ability of the two techniques to reuse the majority of an existing hybrid mesh for typical design changes. Modular mesh generation is used to change the shape of piece of a seafloor pipeline geometry to a completely different configuration. The hybrid mesh movement technique is used to change the twist of a turbomachinery blade, the tip clearance of a rotor blade and to simulate the aeroelastic bending of a wing. Finally, the movement technique is applied to an offshore application where the solution for the original configuration is used as a starting point for solution for a new configuration. The application of both techniques show that the methods can be a powerful addition to the design environment and will facilitate a rapid turnaround when the design geometry changes.

Automatic Identification of Critical Follow-Up Recommendation Sentences in Radiology Reports

PubMed Central

Yetisgen-Yildiz, Meliha; Gunn, Martin L.; Xia, Fei; Payne, Thomas H.

2011-01-01

Communication of follow-up recommendations when abnormalities are identified on imaging studies is prone to error. When recommendations are not systematically identified and promptly communicated to referrers, poor patient outcomes can result. Using information technology can improve communication and improve patient safety. In this paper, we describe a text processing approach that uses natural language processing (NLP) and supervised text classification methods to automatically identify critical recommendation sentences in radiology reports. To increase the classification performance we enhanced the simple unigram token representation approach with lexical, semantic, knowledge-base, and structural features. We tested different combinations of those features with the Maximum Entropy (MaxEnt) classification algorithm. Classifiers were trained and tested with a gold standard corpus annotated by a domain expert. We applied 5-fold cross validation and our best performing classifier achieved 95.60% precision, 79.82% recall, 87.0% F-score, and 99.59% classification accuracy in identifying the critical recommendation sentences in radiology reports. PMID:22195225

Study design in high-dimensional classification analysis.

PubMed

Sánchez, Brisa N; Wu, Meihua; Song, Peter X K; Wang, Wen

2016-10-01

Advances in high throughput technology have accelerated the use of hundreds to millions of biomarkers to construct classifiers that partition patients into different clinical conditions. Prior to classifier development in actual studies, a critical need is to determine the sample size required to reach a specified classification precision. We develop a systematic approach for sample size determination in high-dimensional (large [Formula: see text] small [Formula: see text]) classification analysis. Our method utilizes the probability of correct classification (PCC) as the optimization objective function and incorporates the higher criticism thresholding procedure for classifier development. Further, we derive the theoretical bound of maximal PCC gain from feature augmentation (e.g. when molecular and clinical predictors are combined in classifier development). Our methods are motivated and illustrated by a study using proteomics markers to classify post-kidney transplantation patients into stable and rejecting classes. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Automatic identification of critical follow-up recommendation sentences in radiology reports.

PubMed

Yetisgen-Yildiz, Meliha; Gunn, Martin L; Xia, Fei; Payne, Thomas H

2011-01-01

Communication of follow-up recommendations when abnormalities are identified on imaging studies is prone to error. When recommendations are not systematically identified and promptly communicated to referrers, poor patient outcomes can result. Using information technology can improve communication and improve patient safety. In this paper, we describe a text processing approach that uses natural language processing (NLP) and supervised text classification methods to automatically identify critical recommendation sentences in radiology reports. To increase the classification performance we enhanced the simple unigram token representation approach with lexical, semantic, knowledge-base, and structural features. We tested different combinations of those features with the Maximum Entropy (MaxEnt) classification algorithm. Classifiers were trained and tested with a gold standard corpus annotated by a domain expert. We applied 5-fold cross validation and our best performing classifier achieved 95.60% precision, 79.82% recall, 87.0% F-score, and 99.59% classification accuracy in identifying the critical recommendation sentences in radiology reports.

3D model-based documentation with the Tumor Therapy Manager (TTM) improves TNM staging of head and neck tumor patients.

PubMed

Pankau, Thomas; Wichmann, Gunnar; Neumuth, Thomas; Preim, Bernhard; Dietz, Andreas; Stumpp, Patrick; Boehm, Andreas

2015-10-01

Many treatment approaches are available for head and neck cancer (HNC), leading to challenges for a multidisciplinary medical team in matching each patient with an appropriate regimen. In this effort, primary diagnostics and its reliable documentation are indispensable. A three-dimensional (3D) documentation system was developed and tested to determine its influence on interpretation of these data, especially for TNM classification. A total of 42 HNC patient data sets were available, including primary diagnostics such as panendoscopy, performed and evaluated by an experienced head and neck surgeon. In addition to the conventional panendoscopy form and report, a 3D representation was generated with the "Tumor Therapy Manager" (TTM) software. These cases were randomly re-evaluated by 11 experienced otolaryngologists from five hospitals, half with and half without the TTM data. The accuracy of tumor staging was assessed by pre-post comparison of the TNM classification. TNM staging showed no significant differences in tumor classification (T) with and without 3D from TTM. However, there was a significant decrease in standard deviation from 0.86 to 0.63 via TTM ([Formula: see text]). In nodal staging without TTM, the lymph nodes (N) were significantly underestimated with [Formula: see text] classes compared with [Formula: see text] with TTM ([Formula: see text]). Likewise, the standard deviation was reduced from 0.79 to 0.69 ([Formula: see text]). There was no influence of TTM results on the evaluation of distant metastases (M). TNM staging was more reproducible and nodal staging more accurate when 3D documentation of HNC primary data was available to experienced otolaryngologists. The more precise assessment of the tumor classification with TTM should provide improved decision-making concerning therapy, especially within the interdisciplinary tumor board.

Coated mesh photocatalytic reactor for air treatment applications: comparative study of support materials.

PubMed

Passalía, Claudio; Nocetti, Emanuel; Alfano, Orlando; Brandi, Rodolfo

2017-03-01

An experimental comparative study of different meshes as support materials for photocatalytic applications in gas phase is presented. The photocatalytic oxidation of dichloromethane in air was addressed employing different coated meshes in a laboratory-scale, continuous reactor. Two fiberglass meshes and a stainless steel mesh were studied regarding the catalyst load, adherence, and catalytic activity. Titanium dioxide photocatalyst was immobilized on the meshes by dip-coating cycles. Results indicate the feasibility of the dichloromethane elimination in the three cases. When the number of coating cycles was doubled, the achieved conversion levels were increased twofold for stainless steel and threefold for the fiberglass meshes. One of the fiberglass meshes (FG2) showed the highest reactivity per mass of catalyst and per catalytic surface area.

Array-based Hierarchical Mesh Generation in Parallel

DOE PAGES

Ray, Navamita; Grindeanu, Iulian; Zhao, Xinglin; ...

2015-11-03

In this paper, we describe an array-based hierarchical mesh generation capability through uniform refinement of unstructured meshes for efficient solution of PDE's using finite element methods and multigrid solvers. A multi-degree, multi-dimensional and multi-level framework is designed to generate the nested hierarchies from an initial mesh that can be used for a number of purposes such as multi-level methods to generating large meshes. The capability is developed under the parallel mesh framework “Mesh Oriented dAtaBase” a.k.a MOAB. We describe the underlying data structures and algorithms to generate such hierarchies and present numerical results for computational efficiency and mesh quality. Inmore » conclusion, we also present results to demonstrate the applicability of the developed capability to a multigrid finite-element solver.« less

Towards Improved Finite Element Modelling of the Interaction of Elastic Waves with Complex Defect Geometries

NASA Astrophysics Data System (ADS)

Rajagopal, P.; Drozdz, M.; Lowe, M. J. S.

2009-03-01

A solution to the problem of improving the finite element (FE) modeling of elastic wave-defect interaction is sought by reconsidering the conventional opinion on meshing strategy. The standard approach using uniform square elements imposes severe limitations in representing complex defect outlines but this is thought to improve when the mesh is made finer. Free meshing algorithms available widely in commercial packages of late can cope with difficult features well but they are thought to cause scattering by the irregular mesh itself. This paper examines whether the benefits offered by free meshing in representing defects better outweigh the inaccuracies due to mesh scattering. If using the standard mesh, the questions whether mesh refinement leads to improved results and whether a practical strategy can be constructed are considered.

CNN for breaking text-based CAPTCHA with noise

NASA Astrophysics Data System (ADS)

Liu, Kaixuan; Zhang, Rong; Qing, Ke

2017-07-01

A CAPTCHA ("Completely Automated Public Turing test to tell Computers and Human Apart") system is a program that most humans can pass but current computer programs could hardly pass. As the most common type of CAPTCHAs , text-based CAPTCHA has been widely used in different websites to defense network bots. In order to breaking textbased CAPTCHA, in this paper, two trained CNN models are connected for the segmentation and classification of CAPTCHA images. Then base on these two models, we apply sliding window segmentation and voting classification methods realize an end-to-end CAPTCHA breaking system with high success rate. The experiment results show that our method is robust and effective in breaking text-based CAPTCHA with noise.

Early Wound Morbidity after Open Ventral Hernia Repair with Biosynthetic or Polypropylene Mesh.

PubMed

Sahoo, Sambit; Haskins, Ivy N; Huang, Li-Ching; Krpata, David M; Derwin, Kathleen A; Poulose, Benjamin K; Rosen, Michael J

2017-10-01

Recently introduced slow-resorbing biosynthetic and non-resorbing macroporous polypropylene meshes are being used in hernias with clean-contaminated and contaminated wounds. However, information about the use of biosynthetic meshes and their outcomes compared with polypropylene meshes in clean-contaminated and contaminated cases is lacking. Here we evaluate the use of biosynthetic mesh and polypropylene mesh in elective open ventral hernia repair (OVHR) and investigate differences in early wound morbidity after OVHR within clean-contaminated and contaminated cases. All elective, OVHR with biosynthetic mesh or uncoated polypropylene mesh from January 2013 through October 2016 were identified within the Americas Hernia Society Quality Collaborative. Association of mesh type with 30-day wound events in clean-contaminated or contaminated wounds was investigated using a 1:3 propensity-matched analysis. Biosynthetic meshes were used in 8.5% (175 of 2,051) of elective OVHR, with the majority (57.1%) used in low-risk or comorbid clean cases. Propensity-matched analysis in clean-contaminated and contaminated cases showed no significant difference between biosynthetic mesh and polypropylene mesh groups for 30-day surgical site occurrences (20.7% vs 16.7%; p = 0.49) or unplanned readmission (13.8% vs 9.8%; p = 0.4). However, surgical site infections (22.4% vs 10.9%; p = 0.03), surgical site occurrences requiring procedural intervention (24.1% vs 13.2%; p = 0.049), and reoperation rates (13.8% vs 4.0%; p = 0.009) were significantly higher in the biosynthetic group. Biosynthetic mesh appears to have higher rates of 30-day wound morbidity compared with polypropylene mesh in elective OVHR with clean-contaminated or contaminated wounds. Additional post-market analysis is needed to provide evidence defining best mesh choices, location, and surgical technique for repairing contaminated ventral hernias. Copyright © 2017 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Reconstruction of forest geometries from terrestrial laser scanning point clouds for canopy radiative transfer modelling

NASA Astrophysics Data System (ADS)

Bremer, Magnus; Schmidtner, Korbinian; Rutzinger, Martin

2015-04-01

The architecture of forest canopies is a key parameter for forest ecological issues helping to model the variability of wood biomass and foliage in space and time. In order to understand the nature of subpixel effects of optical space-borne sensors with coarse spatial resolution, hypothetical 3D canopy models are widely used for the simulation of radiative transfer in forests. Thereby, radiation is traced through the atmosphere and canopy geometries until it reaches the optical sensor. For a realistic simulation scene we decompose terrestrial laser scanning point cloud data of leaf-off larch forest plots in the Austrian Alps and reconstruct detailed model ready input data for radiative transfer simulations. The point clouds are pre-classified into primitive classes using Principle Component Analysis (PCA) using scale adapted radius neighbourhoods. Elongated point structures are extracted as tree trunks. The tree trunks are used as seeds for a Dijkstra-growing procedure, in order to obtain single tree segmentation in the interlinked canopies. For the optimized reconstruction of branching architectures as vector models, point cloud skeletonisation is used in combination with an iterative Dijkstra-growing and by applying distance constraints. This allows conducting a hierarchical reconstruction preferring the tree trunk and higher order branches and avoiding over-skeletonization effects. Based on the reconstructed branching architectures, larch needles are modelled based on the hierarchical level of branches and the geometrical openness of the canopy. For radiative transfer simulations, branch architectures are used as mesh geometries representing branches as cylindrical pipes. Needles are either used as meshes or as voxel-turbids. The presented workflow allows an automatic classification and single tree segmentation in interlinked canopies. The iterative Dijkstra-growing using distance constraints generated realistic reconstruction results. As the mesh representation of branches proved to be sufficient for the simulation approach, the modelling of huge amounts of needles is much more efficient in voxel-turbid representation.

A Linear-Elasticity Solver for Higher-Order Space-Time Mesh Deformation

NASA Technical Reports Server (NTRS)

Diosady, Laslo T.; Murman, Scott M.

2018-01-01

A linear-elasticity approach is presented for the generation of meshes appropriate for a higher-order space-time discontinuous finite-element method. The equations of linear-elasticity are discretized using a higher-order, spatially-continuous, finite-element method. Given an initial finite-element mesh, and a specified boundary displacement, we solve for the mesh displacements to obtain a higher-order curvilinear mesh. Alternatively, for moving-domain problems we use the linear-elasticity approach to solve for a temporally discontinuous mesh velocity on each time-slab and recover a continuous mesh deformation by integrating the velocity. The applicability of this methodology is presented for several benchmark test cases.

Immediate effects of the initial FDA notification on the use of surgical mesh for pelvic organ prolapse surgery in medicare beneficiaries.

PubMed

Reynolds, W Stuart; Gold, Karen P; Ni, Shenghua; Kaufman, Melissa R; Dmochowski, Roger R; Penson, David F

2013-04-01

Prompted by increased reports of complications with the use of mesh for pelvic organ prolapse (POP) surgery, the FDA issued an initial public health notification (PHN) in 2008. We proposed to determine if the numbers of POP cases augmented with surgical mesh performed in U.S. Medicare beneficiaries changed relative to this PHN. Using administrative healthcare claims for beneficiaries enrolled in the U.S. Medicare program from 2008 to 2009, we identified women who underwent POP surgery with and without surgical mesh by procedural and diagnosis coding. In addition to comparing cases with and without mesh, we also calculated rates (number of cases per 100,000 female beneficiaries) and compared these relative to the timing of the PHN. We identified 104,185 POP procedures, of which 27,839 (26.7%) included mesh material and 76,346 (73.3%) did not. Between the last three quarters of 2008 and the first three of 2009, the rates of mesh cases increased (40.3-42.1, P < 0.001) and those without mesh decreased (115.5-111.4, P < 0.001). Inpatient procedures decreased and outpatient procedures increased for both those with and without mesh augmentation. For inpatient procedures, the relative use of biologic graft and synthetic mesh material did not vary over the study period. A substantial number of Medicare beneficiaries underwent mesh POP procedures in 2008-2009. However, despite the PHN cautioning about potential mesh complications, the numbers of mesh cases continued to rise in the immediate period after the PHN. Copyright © 2012 Wiley Periodicals, Inc.

Approaches to the automatic generation and control of finite element meshes

NASA Technical Reports Server (NTRS)

Shephard, Mark S.

1987-01-01

The algorithmic approaches being taken to the development of finite element mesh generators capable of automatically discretizing general domains without the need for user intervention are discussed. It is demonstrated that because of the modeling demands placed on a automatic mesh generator, all the approaches taken to date produce unstructured meshes. Consideration is also given to both a priori and a posteriori mesh control devices for automatic mesh generators as well as their integration with geometric modeling and adaptive analysis procedures.

Unstructured mesh algorithms for aerodynamic calculations

NASA Technical Reports Server (NTRS)

Mavriplis, D. J.

1992-01-01

The use of unstructured mesh techniques for solving complex aerodynamic flows is discussed. The principle advantages of unstructured mesh strategies, as they relate to complex geometries, adaptive meshing capabilities, and parallel processing are emphasized. The various aspects required for the efficient and accurate solution of aerodynamic flows are addressed. These include mesh generation, mesh adaptivity, solution algorithms, convergence acceleration, and turbulence modeling. Computations of viscous turbulent two-dimensional flows and inviscid three-dimensional flows about complex configurations are demonstrated. Remaining obstacles and directions for future research are also outlined.

Percept User Manual.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carnes, Brian; Kennon, Stephen Ray

2017-05-01

This document is the main user guide for the Sierra/Percept capabilities including the mesh_adapt and mesh_transfer tools. Basic capabilities for uniform mesh refinement (UMR) and mesh transfers are discussed. Examples are used to provide illustration. Future versions of this manual will include more advanced features such as geometry and mesh smoothing. Additionally, all the options for the mesh_adapt code will be described in detail. Capabilities for local adaptivity in the context of offline adaptivity will also be included. This page intentionally left blank.

Healthcare Text Classification System and its Performance Evaluation: A Source of Better Intelligence by Characterizing Healthcare Text.

PubMed

Srivastava, Saurabh Kumar; Singh, Sandeep Kumar; Suri, Jasjit S

2018-04-13

A machine learning (ML)-based text classification system has several classifiers. The performance evaluation (PE) of the ML system is typically driven by the training data size and the partition protocols used. Such systems lead to low accuracy because the text classification systems lack the ability to model the input text data in terms of noise characteristics. This research study proposes a concept of misrepresentation ratio (MRR) on input healthcare text data and models the PE criteria for validating the hypothesis. Further, such a novel system provides a platform to amalgamate several attributes of the ML system such as: data size, classifier type, partitioning protocol and percentage MRR. Our comprehensive data analysis consisted of five types of text data sets (TwitterA, WebKB4, Disease, Reuters (R8), and SMS); five kinds of classifiers (support vector machine with linear kernel (SVM-L), MLP-based neural network, AdaBoost, stochastic gradient descent and decision tree); and five types of training protocols (K2, K4, K5, K10 and JK). Using the decreasing order of MRR, our ML system demonstrates the mean classification accuracies as: 70.13 ± 0.15%, 87.34 ± 0.06%, 93.73 ± 0.03%, 94.45 ± 0.03% and 97.83 ± 0.01%, respectively, using all the classifiers and protocols. The corresponding AUC is 0.98 for SMS data using Multi-Layer Perceptron (MLP) based neural network. All the classifiers, the best accuracy of 91.84 ± 0.04% is shown to be of MLP-based neural network and this is 6% better over previously published. Further we observed that as MRR decreases, the system robustness increases and validated by standard deviations. The overall text system accuracy using all data types, classifiers, protocols is 89%, thereby showing the entire ML system to be novel, robust and unique. The system is also tested for stability and reliability.

Texturing of continuous LOD meshes with the hierarchical texture atlas

NASA Astrophysics Data System (ADS)

Birkholz, Hermann

2006-02-01

For the rendering of detailed virtual environments, trade-offs have to be made between image quality and rendering time. An immersive experience of virtual reality always demands high frame-rates with the best reachable image qual-ity. Continuous Level of Detail (cLoD) triangle-meshes provide an continuous spectrum of detail for a triangle mesh that can be used to create view-dependent approximations of the environment in real-time. This enables the rendering with a constant number of triangles and thus with constant frame-rates. Normally the construction of such cLoD mesh representations leads to the loss of all texture information of the original mesh. To overcome this problem, a parameter domain can be created, in order to map the surface properties (colour, texture, normal) to it. This parameter domain can be used to map the surface properties back to arbitrary approximations of the original mesh. The parameter domain is often a simplified version of the mesh to be parameterised. This limits the reachable simplification to the domain mesh which has to map the surface of the original mesh with the least possible stretch. In this paper, a hierarchical domain mesh is presented, that scales between very coarse domain meshes and good property-mapping.

Robust moving mesh algorithms for hybrid stretched meshes: Application to moving boundaries problems

NASA Astrophysics Data System (ADS)

Landry, Jonathan; Soulaïmani, Azzeddine; Luke, Edward; Ben Haj Ali, Amine

2016-12-01

A robust Mesh-Mover Algorithm (MMA) approach is designed to adapt meshes of moving boundaries problems. A new methodology is developed from the best combination of well-known algorithms in order to preserve the quality of initial meshes. In most situations, MMAs distribute mesh deformation while preserving a good mesh quality. However, invalid meshes are generated when the motion is complex and/or involves multiple bodies. After studying a few MMA limitations, we propose the following approach: use the Inverse Distance Weighting (IDW) function to produce the displacement field, then apply the Geometric Element Transformation Method (GETMe) smoothing algorithms to improve the resulting mesh quality, and use an untangler to revert negative elements. The proposed approach has been proven efficient to adapt meshes for various realistic aerodynamic motions: a symmetric wing that has suffered large tip bending and twisting and the high-lift components of a swept wing that has moved to different flight stages. Finally, the fluid flow problem has been solved on meshes that have moved and they have produced results close to experimental ones. However, for situations where moving boundaries are too close to each other, more improvements need to be made or other approaches should be taken, such as an overset grid method.

Three-dimensional analysis of implanted magnetic-resonance-visible meshes.

PubMed

Sindhwani, Nikhil; Feola, Andrew; De Keyzer, Frederik; Claus, Filip; Callewaert, Geertje; Urbankova, Iva; Ourselin, Sebastien; D'hooge, Jan; Deprest, Jan

2015-10-01

Our primary objective was to develop relevant algorithms for quantification of mesh position and 3D shape in magnetic resonance (MR) images. In this proof-of-principle study, one patient with severe anterior vaginal wall prolapse was implanted with an MR-visible mesh. High-resolution MR images of the pelvis were acquired 6 weeks and 8 months postsurgery. 3D models were created using semiautomatic segmentation techniques. Conformational changes were recorded quantitatively using part-comparison analysis. An ellipticity measure is proposed to record longitudinal conformational changes in the mesh arms. The surface that is the effective reinforcement provided by the mesh is calculated using a novel methodology. The area of this surface is the effective support area (ESA). MR-visible mesh was clearly outlined in the images, which allowed us to longitudinally quantify mesh configuration between 6 weeks and 8 months after implantation. No significant changes were found in mesh position, effective support area, conformation of the mesh's main body, and arm length during the period of observation. Ellipticity profiles show longitudinal conformational changes in posterior arms. This paper proposes novel methodologies for a systematic 3D assessment of the position and morphology of MR-visible meshes. A novel semiautomatic tool was developed to calculate the effective area of support provided by the mesh, a potentially clinically important parameter.

Biologic meshes are not superior to synthetic meshes in ventral hernia repair: an experimental study with long-term follow-up evaluation.

PubMed

Ditzel, M; Deerenberg, E B; Grotenhuis, N; Harlaar, J J; Monkhorst, K; Bastiaansen-Jenniskens, Y M; Jeekel, J; Lange, J F

2013-10-01

In laparoscopic incisional hernia repair, direct contact between the prosthesis and the abdominal viscera is inevitable, which may lead to an inflammatory reaction resulting in abdominal adhesion formation. This study compared five different synthetic and biologic meshes in terms of adhesion formation, shrinkage, incorporation, and histologic characteristics after a period of 30 and 90 days. In 85 rats, a mesh was positioned intraperitoneally in direct contact with the viscera. Five different meshes were implanted: Prolene (polypropylene), Parietex composite (collagen-coated polyester), Strattice (porcine dermis, non-cross-linked), Surgisis (porcine small intestine submucosa, non-cross-linked), and Permacol (porcine dermis, cross-linked). The meshes were tested in terms of adhesion formation, shrinkage, and incorporation after a period of 30 and 90 days. Additionally, collagen formation after 90 days was determined. Significantly less adhesion formation was observed with Parietex composite (5 %; interquartile range [IQR], 2-5 %) and Strattice (5 %; IQR, 4-10 %) in the long term. In contrast, organs were attached to Permacol with four of seven meshes (57 %), and adhesion coverage of Surgisis mesh was present in 66 % (IQR, 0-100 %) of the cases. After 90 days, the best incorporation was seen with the Parietex composite mesh (79 %; IQR, 61-83 %). After 90 days, major alterations in adhesion formation were seen compared with 30 days. Histologically, Strattice and Parietex composite showed a new mesothelial layer on the visceral side of the mesh. Microscopic degradation and new collagen formation were seen in the Surgisis group. Parietex composite mesh demonstrated the best long-term results compared with all the other meshes. The biologic non-cross-linked mesh, Strattice, showed little adhesion formation and moderate shrinkage but poor incorporation. Biologic meshes are promising, but varying results require a more detailed investigation and demonstrate that biologic meshes are not necessarily superior to synthetic meshes. The significant changes that take place between 30 and 90 days should lead to careful interpretation of short-term experimental results.

Onlay with Adhesive Use Compared with Sublay Mesh Placement in Ventral Hernia Repair: Was Chevrel Right? An Americas Hernia Society Quality Collaborative Analysis.

PubMed

Haskins, Ivy N; Voeller, Guy R; Stoikes, Nathaniel F; Webb, David L; Chandler, Robert G; Phillips, Sharon; Poulose, Benjamin K; Rosen, Michael J

2017-05-01

The use of mesh during ventral hernia repair (VHR) is a well-accepted concept. However, the ideal location of mesh placement remains strongly debated. Although VHR with onlay mesh placement has historically been associated with a high rate of wound events, this surgical approach is technically less challenging than VHR with sublay mesh placement. The purpose of this study was to compare 30-day wound events after onlay mesh placement with adhesive fixation vs those after sublay mesh placement using the Americas Hernia Society Quality Collaborative database. All patients undergoing elective, open VHR with synthetic mesh placement from January 2013 through January 2016 were identified within the Americas Hernia Society Quality Collaborative. Only patients with clean wounds were included. Patients were divided into 2 groups: onlay mesh placement with the use of adhesive and sublay mesh placement. The association of mesh location with 30-day wound events was investigated using a matched analysis. A total of 1,854 patients met inclusion criteria; 1,761 (95.0%) underwent sublay mesh placement and 93 (5.0%) underwent onlay mesh placement with the use of adhesive. A 2:1 sublay to onlay matched analysis was performed based on factors previously shown to influence wound events after VHR. After matching, both groups had a lower mean Ventral Hernia Working Group grade and fewer associated comorbidities. There was no statistically significant difference between the sublay and onlay groups with respect to 30-day surgical site infections (2.9% vs 5.5%; p = 0.30), surgical site occurrences (15.2% vs 7.7%; p = 0.08), or surgical site occurrences requiring procedural intervention (8.2% vs 5.5%; p = 0.42). Ventral hernia repair with onlay mesh placement is a safe alternative to VHR with sublay mesh placement in low-risk patients. Additional studies are needed to determine the long-term mesh outcomes and recurrence rates in both of these groups. Copyright © 2017 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

50 CFR 697.7 - Prohibitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

...-inch (8.3 cm) square stretch mesh (as measured between the centers of opposite knots when stretched taut) or 33/4-inch (9.5 cm) diamond stretch mesh for trawls and 27/8-inch (7.3 cm) stretch mesh for..., in the EEZ when using a mesh size less than 3 1/4-inch (8.3 cm) square stretch mesh (as measured...

50 CFR 697.7 - Prohibitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

...-inch (8.3 cm) square stretch mesh (as measured between the centers of opposite knots when stretched taut) or 33/4-inch (9.5 cm) diamond stretch mesh for trawls and 27/8-inch (7.3 cm) stretch mesh for..., in the EEZ when using a mesh size less than 3 1/4-inch (8.3 cm) square stretch mesh (as measured...

50 CFR 697.7 - Prohibitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

...-inch (8.3 cm) square stretch mesh (as measured between the centers of opposite knots when stretched taut) or 33/4-inch (9.5 cm) diamond stretch mesh for trawls and 27/8-inch (7.3 cm) stretch mesh for..., in the EEZ when using a mesh size less than 3 1/4-inch (8.3 cm) square stretch mesh (as measured...

Automatically classifying sentences in full-text biomedical articles into Introduction, Methods, Results and Discussion.

PubMed

Agarwal, Shashank; Yu, Hong

2009-12-01

Biomedical texts can be typically represented by four rhetorical categories: Introduction, Methods, Results and Discussion (IMRAD). Classifying sentences into these categories can benefit many other text-mining tasks. Although many studies have applied different approaches for automatically classifying sentences in MEDLINE abstracts into the IMRAD categories, few have explored the classification of sentences that appear in full-text biomedical articles. We first evaluated whether sentences in full-text biomedical articles could be reliably annotated into the IMRAD format and then explored different approaches for automatically classifying these sentences into the IMRAD categories. Our results show an overall annotation agreement of 82.14% with a Kappa score of 0.756. The best classification system is a multinomial naïve Bayes classifier trained on manually annotated data that achieved 91.95% accuracy and an average F-score of 91.55%, which is significantly higher than baseline systems. A web version of this system is available online at-http://wood.ims.uwm.edu/full_text_classifier/.

Jali - Unstructured Mesh Infrastructure for Multi-Physics Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garimella, Rao V; Berndt, Markus; Coon, Ethan

2017-04-13

Jali is a parallel unstructured mesh infrastructure library designed for use by multi-physics simulations. It supports 2D and 3D arbitrary polyhedral meshes distributed over hundreds to thousands of nodes. Jali can read write Exodus II meshes along with fields and sets on the mesh and support for other formats is partially implemented or is (https://github.com/MeshToolkit/MSTK), an open source general purpose unstructured mesh infrastructure library from Los Alamos National Laboratory. While it has been made to work with other mesh frameworks such as MOAB and STKmesh in the past, support for maintaining the interface to these frameworks has been suspended formore » now. Jali supports distributed as well as on-node parallelism. Support of on-node parallelism is through direct use of the the mesh in multi-threaded constructs or through the use of "tiles" which are submeshes or sub-partitions of a partition destined for a compute node.« less

Textile properties of synthetic prolapse mesh in response to uniaxial loading.

PubMed

Barone, William R; Moalli, Pamela A; Abramowitch, Steven D

2016-09-01

Although synthetic mesh is associated with superior anatomic outcomes for the repair of pelvic organ prolapse, the benefits of mesh have been questioned because of the relatively high complication rates. To date, the mechanisms that result in such complications are poorly understood, yet the textile characteristics of mesh products are believed to play an important role. Interestingly, the pore diameter of synthetic mesh has been shown to impact the host response after hernia repair greatly, and such findings have served as design criteria for prolapse meshes, with larger pores viewed as more favorable. Although pore size and porosity are well-characterized before implantation, the changes in these textile properties after implantation are unclear; the application of mechanical forces has the potential to greatly alter pore geometries in vivo. Understanding the impact of mechanical loading on the textile properties of mesh is essential for the development of more effective devices for prolapse repair. The objective of this study was to determine the effect of tensile loading and pore orientation on mesh porosity and pore dimensions. In this study, the porosity and pore diameter of 4 currently available prolapse meshes were examined in response to uniaxial tensile loads of 0.1, 5, and 10 N while mimicking clinical loading conditions. The textile properties were compared with those observed for the unloaded mesh. Meshes included Gynemesh PS (Ethicon, Somerville, NJ), UltraPro (Artisyn; Ethicon), Restorelle (Coloplast, Minneapolis, MN), and Alyte Y-mesh (Bard, Covington, GA). In addition to the various pore geometries, 3 orientations of Restorelle (0-, 5-, 45-degree offset) and 2 orientations of UltraPro (0-, 90-degree offset) were examined. In response to uniaxial loading, both porosity and pore diameter dramatically decreased for most mesh products. The application of 5 N led to reductions in porosity for nearly all groups, with values decreasing by as much as 87% (P < .05). On loading to 10 N of force, nearly all mesh products that were tested were found to have porosities that approached 0% and 0 pores with diameters >1 mm. In this study, it was shown that the pore size of current prolapse meshes dramatically decreases in response to mechanical loading. These findings suggest that prolapse meshes, which are more likely to experience tensile forces in vivo relative to hernia repair meshes, have pores that are unfavorable for tissue integration after surgical tensioning and/or loading in urogynecologic surgeries. Such decreases in pore geometry support the hypothesis that regional increases in the concentration of mesh leads to an enhanced local foreign body response. Although pore deformation in transvaginal meshes requires further characterization, the findings presented here provide a mechanical understanding that can be used to recognize potential areas of concern for complex mesh geometries. Understanding mesh mechanics in response to surgical and in vivo loading conditions may provide improved design criteria for mesh and a refinement of surgical techniques, ultimately leading to better patient outcomes. Copyright © 2016 Elsevier Inc. All rights reserved.

[Classifications in forensic medicine and their logical basis].

PubMed

Kovalev, A V; Shmarov, L A; Ten'kov, A A

2014-01-01

The objective of the present study was to characterize the main requirements for the correct construction of classifications used in forensic medicine, with special reference to the errors that occur in the relevant text-books, guidelines, and manuals and the ways to avoid them. This publication continues the series of thematic articles of the authors devoted to the logical errors in the expert conclusions. The preparation of further publications is underway to report the results of the in-depth analysis of the logical errors encountered in expert conclusions, text-books, guidelines, and manuals.

A new multiscale air quality transport model (Fluidity, 4.1.9) using fully unstructured anisotropic adaptive mesh technology

NASA Astrophysics Data System (ADS)

Zheng, J.; Zhu, J.; Wang, Z.; Fang, F.; Pain, C. C.; Xiang, J.

2015-06-01

A new anisotropic hr-adaptive mesh technique has been applied to modelling of multiscale transport phenomena, which is based on a discontinuous Galerkin/control volume discretization on unstructured meshes. Over existing air quality models typically based on static-structured grids using a locally nesting technique, the advantage of the anisotropic hr-adaptive model has the ability to adapt the mesh according to the evolving pollutant distribution and flow features. That is, the mesh resolution can be adjusted dynamically to simulate the pollutant transport process accurately and effectively. To illustrate the capability of the anisotropic adaptive unstructured mesh model, three benchmark numerical experiments have been setup for two-dimensional (2-D) transport phenomena. Comparisons have been made between the results obtained using uniform resolution meshes and anisotropic adaptive resolution meshes.

Past, Present and Future of Surgical Meshes: A Review.

PubMed

Baylón, Karen; Rodríguez-Camarillo, Perla; Elías-Zúñiga, Alex; Díaz-Elizondo, Jose Antonio; Gilkerson, Robert; Lozano, Karen

2017-08-22

Surgical meshes, in particular those used to repair hernias, have been in use since 1891. Since then, research in the area has expanded, given the vast number of post-surgery complications such as infection, fibrosis, adhesions, mesh rejection, and hernia recurrence. Researchers have focused on the analysis and implementation of a wide range of materials: meshes with different fiber size and porosity, a variety of manufacturing methods, and certainly a variety of surgical and implantation procedures. Currently, surface modification methods and development of nanofiber based systems are actively being explored as areas of opportunity to retain material strength and increase biocompatibility of available meshes. This review summarizes the history of surgical meshes and presents an overview of commercial surgical meshes, their properties, manufacturing methods, and observed biological response, as well as the requirements for an ideal surgical mesh and potential manufacturing methods.

Heterogeneous Wireless Mesh Network Technology Evaluation for Space Proximity and Surface Applications

NASA Technical Reports Server (NTRS)

DeCristofaro, Michael A.; Lansdowne, Chatwin A.; Schlesinger, Adam M.

2014-01-01

NASA has identified standardized wireless mesh networking as a key technology for future human and robotic space exploration. Wireless mesh networks enable rapid deployment, provide coverage in undeveloped regions. Mesh networks are also self-healing, resilient, and extensible, qualities not found in traditional infrastructure-based networks. Mesh networks can offer lower size, weight, and power (SWaP) than overlapped infrastructure-perapplication. To better understand the maturity, characteristics and capability of the technology, we developed an 802.11 mesh network consisting of a combination of heterogeneous commercial off-the-shelf devices and opensource firmware and software packages. Various streaming applications were operated over the mesh network, including voice and video, and performance measurements were made under different operating scenarios. During the testing several issues with the currently implemented mesh network technology were identified and outlined for future work.

Robust laser-structured asymmetrical PTFE mesh for underwater directional transportation and continuous collection of gas bubbles

NASA Astrophysics Data System (ADS)

Yin, Kai; Yang, Shuai; Dong, Xinran; Chu, Dongkai; Duan, Ji-An; He, Jun

2018-06-01

We report a simple, efficient method to fabricate micro/nanoscale hierarchical structures on one side of polytetrafluoroethylene mesh surfaces, using one-step femtosecond laser direct writing technology. The laser-treated surface exhibits superhydrophobicity in air and superaerophilicity in water, resulting in the mesh possessing the hydrophobic/superhydrophobic asymmetrical property. Bubbles can pass through the mesh from the untreated side to the laser-treated side but cannot pass through the mesh in the opposite direction. The asymmetrical mesh can therefore be designed for the directional transportation and continuous collection of gas bubbles in aqueous environments. Furthermore, the asymmetrical mesh shows excellent stability during corrosion and abrasion tests. These findings may provide an efficient route for fabricating a durable asymmetrical mesh for the directional and continuous transport of gas bubbles.

Biomechanical properties of synthetic surgical meshes for pelvic prolapse repair.

PubMed

Todros, S; Pavan, P G; Natali, A N

2015-03-01

Synthetic meshes are widely used for surgical repair of different kind of prolapses. In the light of the experience of abdominal wall repair, similar prostheses are currently used in the pelvic region, to restore physiological anatomy after organ prolapse into the vaginal wall, that represent a recurrent dysfunction. For this purpose, synthetic meshes are surgically positioned in contact with the anterior and/or posterior vaginal wall, to inferiorly support prolapsed organs. Nonetheless, while mesh implantation restores physiological anatomy, it is often associated with different complications in the vaginal region. These potentially dangerous effects induce the surgical community to reconsider the safety and efficacy of mesh transvaginal placement. For this purpose, the evaluation of state-of-the-art research may provide the basis for a comprehensive analysis of mesh compatibility and functionality. The aim of this work is to review synthetic surgical meshes for pelvic organs prolapse repair, taking into account the mechanics of mesh material and structure, and to relate them with pelvic and vaginal tissue biomechanics. Synthetic meshes are currently available in different chemical composition, fiber and textile conformations. Material and structural properties are key factors in determining mesh biochemical and mechanical compatibility in vivo. The most significant results on vaginal tissue and surgical meshes mechanical characterization are here reported and discussed. Moreover, computational models of the pelvic region, which could support the surgeon in the evaluation of mesh performances in physiological conditions, are recalled. Copyright © 2015 Elsevier Ltd. All rights reserved.

Monte Carlo simulation and film dosimetry for electron therapy in vicinity of a titanium mesh

PubMed Central

Rostampour, Masoumeh; Roayaei, Mahnaz

2014-01-01

Titanium (Ti) mesh plates are used as a bone replacement in brain tumor surgeries. In the case of radiotherapy, these plates might interfere with the beam path. The purpose of this study is to evaluate the effect of titanium mesh on the dose distribution of electron fields. Simulations were performed using Monte Carlo BEAMnrc and DOSXYZnrc codes for 6 and 10 MeV electron beams. In Monte Carlo simulation, the shape of the titanium mesh was simulated. The simulated titanium mesh was considered as the one which is used in head and neck surgery with a thickness of 0.055 cm. First, by simulation, the percentage depth dose was obtained while the titanium mesh was present, and these values were then compared with the depth dose of homogeneous phantom with no titanium mesh. In the experimental measurements, the values of depth dose with titanium mesh and without titanium mesh in various depths were measured. The experiments were performed using a RW3 phantom with GAFCHROMIC EBT2 film. The results of experimental measurements were compared with values of depth dose obtained by simulation. In Monte Carlo simulation, as well as experimental measurements, for the voxels immediately beyond the titanium mesh, the change of the dose were evaluated. For this purpose the ratio of the dose for the case with titanium to the case without titanium was calculated as a function of titanium depth. For the voxels before the titanium mesh there was always an increase of the dose up to 13% with respect to the same voxel with no titanium mesh. This is because of the increased back scattering effect of the titanium mesh. The results also showed that for the voxel right beyond the titanium mesh, there is an increased or decreased dose to soft tissues, depending on the depth of the titanium mesh. For the regions before the depth of maximum dose, there is an increase of the dose up to 10% compared to the dose of the same depth in homogeneous phantom. Beyond the depth of maximum dose, there was a 16% decrease in dose. For both 6 and 10 MeV, before the titanium mesh, there was always an increase in dose. If titanium mesh is placed in buildup region, it causes an increase of the dose and could lead to overdose of the adjacent tissue, whereas if titanium mesh is placed beyond the buildup region, it would lead to a decrease in dose compared to the homogenous tissue. PACS number: 87.53.Bn PMID:25207397

Determination of the optimal mesh parameters for Iguassu centrifuge flow and separation calculations

NASA Astrophysics Data System (ADS)

Romanihin, S. M.; Tronin, I. V.

2016-09-01

We present the method and the results of the determination for optimal computational mesh parameters for axisymmetric modeling of flow and separation in the Iguasu gas centrifuge. The aim of this work was to determine the mesh parameters which provide relatively low computational cost whithout loss of accuracy. We use direct search optimization algorithm to calculate optimal mesh parameters. Obtained parameters were tested by the calculation of the optimal working regime of the Iguasu GC. Separative power calculated using the optimal mesh parameters differs less than 0.5% from the result obtained on the detailed mesh. Presented method can be used to determine optimal mesh parameters of the Iguasu GC with different rotor speeds.

Dynamic mesh adaption for triangular and tetrahedral grids

NASA Technical Reports Server (NTRS)

Biswas, Rupak; Strawn, Roger

1993-01-01

The following topics are discussed: requirements for dynamic mesh adaption; linked-list data structure; edge-based data structure; adaptive-grid data structure; three types of element subdivision; mesh refinement; mesh coarsening; additional constraints for coarsening; anisotropic error indicator for edges; unstructured-grid Euler solver; inviscid 3-D wing; and mesh quality for solution-adaptive grids. The discussion is presented in viewgraph form.

Tetrahedral and polyhedral mesh evaluation for cerebral hemodynamic simulation--a comparison.

PubMed

Spiegel, Martin; Redel, Thomas; Zhang, Y; Struffert, Tobias; Hornegger, Joachim; Grossman, Robert G; Doerfler, Arnd; Karmonik, Christof

2009-01-01

Computational fluid dynamic (CFD) based on patient-specific medical imaging data has found widespread use for visualizing and quantifying hemodynamics in cerebrovascular disease such as cerebral aneurysms or stenotic vessels. This paper focuses on optimizing mesh parameters for CFD simulation of cerebral aneurysms. Valid blood flow simulations strongly depend on the mesh quality. Meshes with a coarse spatial resolution may lead to an inaccurate flow pattern. Meshes with a large number of elements will result in unnecessarily high computation time which is undesirable should CFD be used for planning in the interventional setting. Most CFD simulations reported for these vascular pathologies have used tetrahedral meshes. We illustrate the use of polyhedral volume elements in comparison to tetrahedral meshing on two different geometries, a sidewall aneurysm of the internal carotid artery and a basilar bifurcation aneurysm. The spatial mesh resolution ranges between 5,119 and 228,118 volume elements. The evaluation of the different meshes was based on the wall shear stress previously identified as a one possible parameter for assessing aneurysm growth. Polyhedral meshes showed better accuracy, lower memory demand, shorter computational speed and faster convergence behavior (on average 369 iterations less).

Anatomically Realistic Three-Dimensional Meshes of the Pelvic Floor & Anal Canal for Finite Element Analysis

PubMed Central

Noakes, Kimberley F.; Bissett, Ian P.; Pullan, Andrew J.; Cheng, Leo K.

2014-01-01

Three anatomically realistic meshes, suitable for finite element analysis, of the pelvic floor and anal canal regions have been developed to provide a framework with which to examine the mechanics, via finite element analysis of normal function within the pelvic floor. Two cadaver-based meshes were produced using the Visible Human Project (male and female) cryosection data sets, and a third mesh was produced based on MR image data from a live subject. The Visible Man (VM) mesh included 10 different pelvic structures while the Visible Woman and MRI meshes contained 14 and 13 structures respectively. Each image set was digitized and then finite element meshes were created using an iterative fitting procedure with smoothing constraints calculated from ‘L’-curves. These weights produced accurate geometric meshes of each pelvic structure with average Root Mean Square (RMS) fitting errors of less than 1.15 mm. The Visible Human cadaveric data provided high resolution images, however, the cadaveric meshes lacked the normal dynamic form of living tissue and suffered from artifacts related to postmortem changes. The lower resolution MRI mesh was able to accurately portray structure of the living subject and paves the way for dynamic, functional modeling. PMID:18317929

Wind Farm LES Simulations Using an Overset Methodology

NASA Astrophysics Data System (ADS)

Ananthan, Shreyas; Yellapantula, Shashank

2017-11-01

Accurate simulation of wind farm wakes under realistic atmospheric inflow conditions and complex terrain requires modeling a wide range of length and time scales. The computational domain can span several kilometers while requiring mesh resolutions in O(10-6) to adequately resolve the boundary layer on the blade surface. Overset mesh methodology offers an attractive option to address the disparate range of length scales; it allows embedding body-confirming meshes around turbine geomtries within nested wake capturing meshes of varying resolutions necessary to accurately model the inflow turbulence and the resulting wake structures. Dynamic overset hole-cutting algorithms permit relative mesh motion that allow this nested mesh structure to track unsteady inflow direction changes, turbine control changes (yaw and pitch), and wake propagation. An LES model with overset mesh for localized mesh refinement is used to analyze wind farm wakes and performance and compared with local mesh refinements using non-conformal (hanging node) unstructured meshes. Turbine structures will be modeled using both actuator line approaches and fully-resolved structures to test the efficacy of overset methods for wind farm applications. Exascale Computing Project (ECP), Project Number: 17-SC-20-SC, a collaborative effort of two DOE organizations - the Office of Science and the National Nuclear Security Administration.

Mesh infrastructure for coupled multiprocess geophysical simulations

DOE PAGES

Garimella, Rao V.; Perkins, William A.; Buksas, Mike W.; ...

2014-01-01

We have developed a sophisticated mesh infrastructure capability to support large scale multiphysics simulations such as subsurface flow and reactive contaminant transport at storage sites as well as the analysis of the effects of a warming climate on the terrestrial arctic. These simulations involve a wide range of coupled processes including overland flow, subsurface flow, freezing and thawing of ice rich soil, accumulation, redistribution and melting of snow, biogeochemical processes involving plant matter and finally, microtopography evolution due to melting and degradation of ice wedges below the surface. In addition to supporting the usual topological and geometric queries about themore » mesh, the mesh infrastructure adds capabilities such as identifying columnar structures in the mesh, enabling deforming of the mesh subject to constraints and enabling the simultaneous use of meshes of different dimensionality for subsurface and surface processes. The generic mesh interface is capable of using three different open source mesh frameworks (MSTK, MOAB and STKmesh) under the hood allowing the developers to directly compare them and choose one that is best suited for the application's needs. We demonstrate the results of some simulations using these capabilities as well as present a comparison of the performance of the different mesh frameworks.« less

Monitoring and evaluation of wire mesh forming life

NASA Astrophysics Data System (ADS)

Enemuoh, Emmanuel U.; Zhao, Ping; Kadlec, Alec

2018-03-01

Forming tables are used with stainless steel wire mesh conveyor belts to produce variety of products. The forming tables will typically run continuously for several days, with some hours of scheduled downtime for maintenance, cleaning and part replacement after several weeks of operation. The wire mesh conveyor belts show large variation in their remaining life due to associated variations in their nominal thicknesses. Currently the industry is dependent on seasoned operators to determine the replacement time for the wire mesh formers. The drawback of this approach is inconsistency in judgements made by different operators and lack of data knowledge that can be used to develop decision making system that will be more consistent with wire mesh life prediction and replacement time. In this study, diagnostic measurements about the health of wire mesh former is investigated and developed. The wire mesh quality characteristics considered are thermal measurement, tension property, gage thickness, and wire mesh wear. The results show that real time thermal sensor and wear measurements would provide suitable data for the estimation of wire mesh failure, therefore, can be used as a diagnostic parameter for developing structural health monitoring (SHM) system for stainless steel wire mesh formers.

Assessing the impact of short-term surgical education on practice: a retrospective study of the introduction of mesh for inguinal hernia repair in sub-Saharan Africa.

PubMed

Wang, Y T; Meheš, M M; Naseem, H-R; Ibrahim, M; Butt, M A; Ahmed, N; Wahab Bin Adam, M A; Issah, A-W; Mohammed, I; Goldstein, S D; Cartwright, K; Abdullah, F

2014-08-01

Inguinal hernia repair is the most common general surgery operation performed globally. However, the adoption of tension-free hernia repair with mesh has been limited in low-income settings, largely due to a lack of technical training and resources. The present study evaluates the impact of a 2-day training course instructing use of polypropylene mesh for inguinal hernia repair on the practice patterns of sub-Saharan African physicians. A surgical training course on tension-free mesh repair of hernias was provided to 16 physicians working in rural Ghanaian and Liberian hospitals. Three physicians were requested to prospectively record all their inguinal hernia surgeries, performed with or without mesh, during the 14-month period following the training. Demographic variables, diagnoses, and complications were collected by an independent data collector for mesh and non-mesh procedures. Surgery with mesh increased significantly following intervention, from near negligible levels prior to the training to 8.1 % of all inguinal hernia repairs afterwards. Mesh repair accounted for 90.8 % of recurrent hernia repairs and 2.9 % of primary hernia repairs after training. Overall complication rates between mesh and non-mesh procedures were not significantly different (p = 0.20). Three physicians who participated in an intensive education course were routinely using mesh for inguinal hernia repair 14 months after the training. This represents a significant change in practice pattern. Complication rates between patients who underwent inguinal hernia repairs with and without mesh were comparable. The present study provides evidence that short-term surgical training initiatives can have a substantial impact on local healthcare practice in resource-limited settings.

Hexahedral mesh generation via the dual arrangement of surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitchell, S.A.; Tautges, T.J.

1997-12-31

Given a general three-dimensional geometry with a prescribed quadrilateral surface mesh, the authors consider the problem of constructing a hexahedral mesh of the geometry whose boundary is exactly the prescribed surface mesh. Due to the specialized topology of hexahedra, this problem is more difficult than the analogous one for tetrahedra. Folklore has maintained that a surface mesh must have a constrained structure in order for there to exist a compatible hexahedral mesh. However, they have proof that a surface mesh need only satisfy mild parity conditions, depending on the topology of the three-dimensional geometry, for there to exist a compatiblemore » hexahedral mesh. The proof is based on the realization that a hexahedral mesh is dual to an arrangement of surfaces, and the quadrilateral surface mesh is dual to the arrangement of curves bounding these surfaces. The proof is constructive and they are currently developing an algorithm called Whisker Weaving (WW) that mirrors the proof steps. Given the bounding curves, WW builds the topological structure of an arrangement of surfaces having those curves as its boundary. WW progresses in an advancing front manner. Certain local rules are applied to avoid structures that lead to poor mesh quality. Also, after the arrangement is constructed, additional surfaces are inserted to separate features, so e.g., no two hexahedra share more than one quadrilateral face. The algorithm has generated meshes for certain non-trivial problems, but is currently unreliable. The authors are exploring strategies for consistently selecting which portion of the surface arrangement to advance based on the existence proof. This should lead us to a robust algorithm for arbitrary geometries and surface meshes.« less

Effects of mesenchymal stem cell and fibroblast coating on immunogenic potential of prosthetic meshes in vitro.

PubMed

Gao, Yue; Krpata, David M; Criss, Cory N; Liu, Lijia; Posielski, Natasza; Rosen, Michael J; Novitsky, Yuri W

2014-08-01

The aim of this study was to reveal the effect of fibroblast or mesenchymal stem cell (MSC) coating on the mesh-induced production of IL-1β, IL-6, and VEGF by macrophages. Four commonly used surgical meshes were tested in this study, including Parietex, SoftMesh, TIGR, and Strattice. One-square-centimeter pieces of each mesh were placed on top of a monolayer of human fibroblasts or rat MSCs. The coating status was monitored with a light microscope. The human promonocytic cell line U937 was induced to differentiate into macrophages (MΦ). Three weeks later, meshes were transferred to new 24-well plates and cocultured with the MΦs for 72 h. Culture medium was collected and analyzed for IL-1β, IL-6, and VEGF production using standard ELISA essays. Parallel mesh samples were fixed with paraformaldehyde or glutaraldehyde for histology or transmission electronic microscopy (TEM) analyses, respectively. Uncoated meshes induced increased production of all three cytokines compared with macrophages cultured alone. HF coating further increased the production of both IL-6 and VEGF but reduced IL-1β production. Except for the SoftMesh group, MSC coating significantly blunted release of all cytokines to levels even lower than with MΦs cultured alone. MΦs tended to deteriorate in the presence of MSCs. Both histology and TEM revealed intimate interactions between cell-coated meshes and MΦs. Cytokine response to fibroblast coating varied, while MSC coating blunted the immunogenic effect of both synthetic and biologic meshes in vitro. Cell coating appears to affect mesh biocompatibility and may become a key process in mesh evolution.

Transvaginal mesh in the media following the 2011 US food and drug administration public health notification update.

PubMed

Koo, Kevin; Gormley, E Ann

2017-02-01

Prompted by patients' changing perceptions of transvaginal mesh, this study examines how mesh has been reported in the news following the 2011 US Food and Drug Administration (FDA) updated notification about the use of mesh in the treatment of pelvic organ prolapse. Two national newspaper databases were queried for articles discussing transvaginal mesh published within 3 years of the FDA announcement. Content analysis included headline subjects, mesh-related complications, quoted sources, and the FDA recommendations. To determine whether more widely read sources publish higher quality reporting, a subgroup analysis was conducted based on newspaper circulation. Ninety-five articles met inclusion criteria. Mesh-related litigation was the most common headline subject (36 articles, 38%), and 54% of all articles referenced legal action. Fifty-seven articles (60%) cited at least one mesh-related complication. Only 18 articles (19%) quoted surgeons who use transvaginal mesh. For the FDA update, 40% of articles that first reported the announcement accurately specified that it applies to mesh for prolapse, not incontinence. This ambiguity persisted: half of all articles cited the warning, but only 23% distinguished between prolapse and incontinence. Higher newspaper circulation did not significantly improve the quality of reporting about the content or context of the FDA's recommendations. Despite frequent media coverage of transvaginal mesh and its complications since 2011, very few news sources that cited the FDA warning distinguished between prolapse and incontinence. Given prevalent reporting of mesh-related litigation, the findings raise concern about how patients perceive the safety and efficacy of transvaginal mesh, regardless of indication. Neurourol. Urodynam. 36:329-332, 2017. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Methanethiol Concentrations and Sea-Air Fluxes in the Subarctic NE Pacific Ocean

NASA Astrophysics Data System (ADS)

Kiene, R. P.; Williams, T. E.; Esson, K.; Tortell, P. D.; Dacey, J. W. H.

2017-12-01

Exchange of volatile organic sulfur from the ocean to the atmosphere impacts the global sulfur cycle and the climate system and is thought to occur mainly via the gas dimethylsulfide (DMS). DMS is produced during degradation of the abundant phytoplankton osmolyte dimethylsulfoniopropionate (DMSP) but bacteria can also convert dissolved DMSP into the sulfur gas methanethiol (MeSH). MeSH has been difficult to measure in seawater because of its high chemical and biological reactivity and, thus, information on MeSH concentrations, distribution and sea-air fluxes is limited. We measured MeSH in the northeast subarctic Pacific Ocean in July 2016, along transects with strong phytoplankton abundance gradients. Water samples obtained with Niskin bottles were analyzed for MeSH by purge-and-trap gas chromatography. Depth profiles showed that MeSH concentrations were high near the surface and declined with depth. Surface waters (5 m depth) had an average MeSH concentration of 0.75 nM with concentrations reaching up to 3nM. MeSH concentrations were correlated (r = 0.47) with microbial turnover of dissolved DMSP which ranged up to 236 nM per day. MeSH was also correlated with total DMSP (r = 0.93) and dissolved DMS (r = 0.63), supporting the conclusion that DMSP was a major precursor of MeSH. Surface water MeSH:DMS concentration ratios averaged 0.19 and ranged up to 0.50 indicating that MeSH was a significant fraction of the volatile sulfur pool in surface waters. Sea-air fluxes of MeSH averaged 15% of the combined DMS+MeSH flux, therefore MeSH contributed an important fraction of the sulfur emitted to the atmosphere from the subarctic NE Pacific Ocean.

Adaptive Meshing Techniques for Viscous Flow Calculations on Mixed Element Unstructured Meshes

NASA Technical Reports Server (NTRS)

Mavriplis, D. J.

1997-01-01

An adaptive refinement strategy based on hierarchical element subdivision is formulated and implemented for meshes containing arbitrary mixtures of tetrahendra, hexahendra, prisms and pyramids. Special attention is given to keeping memory overheads as low as possible. This procedure is coupled with an algebraic multigrid flow solver which operates on mixed-element meshes. Inviscid flows as well as viscous flows are computed an adaptively refined tetrahedral, hexahedral, and hybrid meshes. The efficiency of the method is demonstrated by generating an adapted hexahedral mesh containing 3 million vertices on a relatively inexpensive workstation.

METHOD OF PREPARING A CERAMIC FUEL ELEMENT

DOEpatents

Ross, W.T.; Bloomster, C.H.; Bardsley, R.E.

1963-09-01

A method is described for preparing a fuel element from -325 mesh PuO/ sub 2/ and -20 mesh UO/sub 2/, and the steps of screening --325 mesh UO/sub 2/ from the -20 mesh UO/sub 2/, mixing PuO/sub 2/ with the --325 mesh UO/sub 2/, blending this mixture with sufficient --20 mesh UO/sub 2/ to obtain the desired composition, introducing the blend into a metal tube, repeating the procedure until the tube is full, and vibrating the tube to compact the powder are included. (AEC)

Key-phrase based classification of public health web pages.

PubMed

Dolamic, Ljiljana; Boyer, Célia

2013-01-01

This paper describes and evaluates the public health web pages classification model based on key phrase extraction and matching. Easily extendible both in terms of new classes as well as the new language this method proves to be a good solution for text classification faced with the total lack of training data. To evaluate the proposed solution we have used a small collection of public health related web pages created by a double blind manual classification. Our experiments have shown that by choosing the adequate threshold value the desired value for either precision or recall can be achieved.

GeneMesh: a web-based microarray analysis tool for relating differentially expressed genes to MeSH terms.

PubMed

Jani, Saurin D; Argraves, Gary L; Barth, Jeremy L; Argraves, W Scott

2010-04-01

An important objective of DNA microarray-based gene expression experimentation is determining inter-relationships that exist between differentially expressed genes and biological processes, molecular functions, cellular components, signaling pathways, physiologic processes and diseases. Here we describe GeneMesh, a web-based program that facilitates analysis of DNA microarray gene expression data. GeneMesh relates genes in a query set to categories available in the Medical Subject Headings (MeSH) hierarchical index. The interface enables hypothesis driven relational analysis to a specific MeSH subcategory (e.g., Cardiovascular System, Genetic Processes, Immune System Diseases etc.) or unbiased relational analysis to broader MeSH categories (e.g., Anatomy, Biological Sciences, Disease etc.). Genes found associated with a given MeSH category are dynamically linked to facilitate tabular and graphical depiction of Entrez Gene information, Gene Ontology information, KEGG metabolic pathway diagrams and intermolecular interaction information. Expression intensity values of groups of genes that cluster in relation to a given MeSH category, gene ontology or pathway can be displayed as heat maps of Z score-normalized values. GeneMesh operates on gene expression data derived from a number of commercial microarray platforms including Affymetrix, Agilent and Illumina. GeneMesh is a versatile web-based tool for testing and developing new hypotheses through relating genes in a query set (e.g., differentially expressed genes from a DNA microarray experiment) to descriptors making up the hierarchical structure of the National Library of Medicine controlled vocabulary thesaurus, MeSH. The system further enhances the discovery process by providing links between sets of genes associated with a given MeSH category to a rich set of html linked tabular and graphic information including Entrez Gene summaries, gene ontologies, intermolecular interactions, overlays of genes onto KEGG pathway diagrams and heatmaps of expression intensity values. GeneMesh is freely available online at http://proteogenomics.musc.edu/genemesh/.

Patterning of polymer nanofiber meshes by electrospinning for biomedical applications

PubMed Central

Neves, Nuno M; Campos, Rui; Pedro, Adriano; Cunha, José; Macedo, Francisco; Reis, Rui L

2007-01-01

The end-product of the electrospinning process is typically a randomly aligned fiber mesh or membrane. This is a result of the electric field generated between the drop of polymer solution at the needle and the collector. The developed electric field causes the stretching of the fibers and their random deposition. By judicious selection of the collector architecture, it is thus possible to develop other morphologies on the nanofiber meshes. The aim of this work is to prepare fiber meshes using various patterned collectors with specific dimensions and designs and to evaluate how those patterns can affect the properties of the meshes relevant to biomedical applications. This study aims at verifying whether it is possible to control the architecture of the fiber meshes by tailoring the geometry of the collector. Three different metallic collector topographies are used to test this hypothesis. Electrospun nonwoven patterned meshes of polyethylene oxide (PEO) and poly(ε-capro-lactone) (PCL) were successfully prepared. Those fiber meshes were analyzed by scanning electron microscopy (SEM). Both mechanical properties of the meshes and cell contacting experiments were performed to test the effect of the produced patterns over the properties of the meshes relevant for biomedical applications. The present study will evaluate cell adhesion sensitivity to the patterns generated and the effect of those patterns on the tensile properties of the fiber meshes. PMID:18019842

MeshVoro: A Three-Dimensional Voronoi Mesh Building Tool for the TOUGH Family of Codes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freeman, C. M.; Boyle, K. L.; Reagan, M.

2013-09-30

Few tools exist for creating and visualizing complex three-dimensional simulation meshes, and these have limitations that restrict their application to particular geometries and circumstances. Mesh generation needs to trend toward ever more general applications. To that end, we have developed MeshVoro, a tool that is based on the Voro (Rycroft 2009) library and is capable of generating complex threedimensional Voronoi tessellation-based (unstructured) meshes for the solution of problems of flow and transport in subsurface geologic media that are addressed by the TOUGH (Pruess et al. 1999) family of codes. MeshVoro, which includes built-in data visualization routines, is a particularly usefulmore » tool because it extends the applicability of the TOUGH family of codes by enabling the scientifically robust and relatively easy discretization of systems with challenging 3D geometries. We describe several applications of MeshVoro. We illustrate the ability of the tool to straightforwardly transform a complex geological grid into a simulation mesh that conforms to the specifications of the TOUGH family of codes. We demonstrate how MeshVoro can describe complex system geometries with a relatively small number of grid blocks, and we construct meshes for geometries that would have been practically intractable with a standard Cartesian grid approach. We also discuss the limitations and appropriate applications of this new technology.« less

Acquisition Order of Coherence Relations in Turkish

ERIC Educational Resources Information Center

Demirgunes, Sercan

2015-01-01

Coherence as one of the criteria for textuality is the main element of a well-produced text. In the literature, there are many studies on the classification of coherence relations. Although there are different classifications on coherence relations, similar findings are reported regarding the acquisition order of coherence relations in different…

Le Predicat Adjectif en Esperanto (The Predicate Adjective in Esperanto)

ERIC Educational Resources Information Center

Lo Jocomo, Francois

1977-01-01

A study of the predicate adjective in Esperanto based on the opposition established between the complementary classifications, monemes and words. Because morphological complications do not exist in Esperanto, study of the two classifications could proceed to the benefit of the study of other languages. (Text is in French.) (AMH)

Enhancing Vocabulary Acquisition Through Reading: A Hierarchy of Text-Related Exercise Types.

ERIC Educational Resources Information Center

Paribakht, T. Sima; Wesche, Marjorie

1996-01-01

Presents a classification scheme for reading-related exercises advocated in English-as-a-Foreign-Language textbooks. The scheme proposes a hierarchy of the degree and type of mental processing required by various vocabulary exercises. The categories of classification are selective attention, recognition, manipulation, interpretation and…

Dynamic mesh for TCAD modeling with ECORCE

NASA Astrophysics Data System (ADS)

Michez, A.; Boch, J.; Touboul, A.; Saigné, F.

2016-08-01

Mesh generation for TCAD modeling is challenging. Because densities of carriers can change by several orders of magnitude in thin areas, a significant change of the solution can be observed for two very similar meshes. The mesh must be defined at best to minimize this change. To address this issue, a criterion based on polynomial interpolation on adjacent nodes is proposed that adjusts accurately the mesh to the gradients of Degrees of Freedom. Furthermore, a dynamic mesh that follows changes of DF in DC and transient mode is a powerful tool for TCAD users. But, in transient modeling, adding nodes to a mesh induces oscillations in the solution that appears as spikes at the current collected at the contacts. This paper proposes two schemes that solve this problem. Examples show that using these techniques, the dynamic mesh generator of the TCAD tool ECORCE handle semiconductors devices in DC and transient mode.

Past, Present and Future of Surgical Meshes: A Review

PubMed Central

Baylón, Karen; Rodríguez-Camarillo, Perla; Elías-Zúñiga, Alex; Díaz-Elizondo, Jose Antonio; Gilkerson, Robert; Lozano, Karen

2017-01-01

Surgical meshes, in particular those used to repair hernias, have been in use since 1891. Since then, research in the area has expanded, given the vast number of post-surgery complications such as infection, fibrosis, adhesions, mesh rejection, and hernia recurrence. Researchers have focused on the analysis and implementation of a wide range of materials: meshes with different fiber size and porosity, a variety of manufacturing methods, and certainly a variety of surgical and implantation procedures. Currently, surface modification methods and development of nanofiber based systems are actively being explored as areas of opportunity to retain material strength and increase biocompatibility of available meshes. This review summarizes the history of surgical meshes and presents an overview of commercial surgical meshes, their properties, manufacturing methods, and observed biological response, as well as the requirements for an ideal surgical mesh and potential manufacturing methods. PMID:28829367

Assessment of Hybrid High-Order methods on curved meshes and comparison with discontinuous Galerkin methods

NASA Astrophysics Data System (ADS)

Botti, Lorenzo; Di Pietro, Daniele A.

2018-10-01

We propose and validate a novel extension of Hybrid High-Order (HHO) methods to meshes featuring curved elements. HHO methods are based on discrete unknowns that are broken polynomials on the mesh and its skeleton. We propose here the use of physical frame polynomials over mesh elements and reference frame polynomials over mesh faces. With this choice, the degree of face unknowns must be suitably selected in order to recover on curved meshes the same convergence rates as on straight meshes. We provide an estimate of the optimal face polynomial degree depending on the element polynomial degree and on the so-called effective mapping order. The estimate is numerically validated through specifically crafted numerical tests. All test cases are conducted considering two- and three-dimensional pure diffusion problems, and include comparisons with discontinuous Galerkin discretizations. The extension to agglomerated meshes with curved boundaries is also considered.

Page layout analysis and classification for complex scanned documents

NASA Astrophysics Data System (ADS)

Erkilinc, M. Sezer; Jaber, Mustafa; Saber, Eli; Bauer, Peter; Depalov, Dejan

2011-09-01

A framework for region/zone classification in color and gray-scale scanned documents is proposed in this paper. The algorithm includes modules for extracting text, photo, and strong edge/line regions. Firstly, a text detection module which is based on wavelet analysis and Run Length Encoding (RLE) technique is employed. Local and global energy maps in high frequency bands of the wavelet domain are generated and used as initial text maps. Further analysis using RLE yields a final text map. The second module is developed to detect image/photo and pictorial regions in the input document. A block-based classifier using basis vector projections is employed to identify photo candidate regions. Then, a final photo map is obtained by applying probabilistic model based on Markov random field (MRF) based maximum a posteriori (MAP) optimization with iterated conditional mode (ICM). The final module detects lines and strong edges using Hough transform and edge-linkages analysis, respectively. The text, photo, and strong edge/line maps are combined to generate a page layout classification of the scanned target document. Experimental results and objective evaluation show that the proposed technique has a very effective performance on variety of simple and complex scanned document types obtained from MediaTeam Oulu document database. The proposed page layout classifier can be used in systems for efficient document storage, content based document retrieval, optical character recognition, mobile phone imagery, and augmented reality.

Optimal classification for the diagnosis of duchenne muscular dystrophy images using support vector machines.

PubMed

Zhang, Ming-Huan; Ma, Jun-Shan; Shen, Ying; Chen, Ying

2016-09-01

This study aimed to investigate the optimal support vector machines (SVM)-based classifier of duchenne muscular dystrophy (DMD) magnetic resonance imaging (MRI) images. T1-weighted (T1W) and T2-weighted (T2W) images of the 15 boys with DMD and 15 normal controls were obtained. Textural features of the images were extracted and wavelet decomposed, and then, principal features were selected. Scale transform was then performed for MRI images. Afterward, SVM-based classifiers of MRI images were analyzed based on the radical basis function and decomposition levels. The cost (C) parameter and kernel parameter [Formula: see text] were used for classification. Then, the optimal SVM-based classifier, expressed as [Formula: see text]), was identified by performance evaluation (sensitivity, specificity and accuracy). Eight of 12 textural features were selected as principal features (eigenvalues [Formula: see text]). The 16 SVM-based classifiers were obtained using combination of (C, [Formula: see text]), and those with lower C and [Formula: see text] values showed higher performances, especially classifier of [Formula: see text]). The SVM-based classifiers of T1W images showed higher performance than T1W images at the same decomposition level. The T1W images in classifier of [Formula: see text]) at level 2 decomposition showed the highest performance of all, and its overall correct sensitivity, specificity, and accuracy reached 96.9, 97.3, and 97.1 %, respectively. The T1W images in SVM-based classifier [Formula: see text] at level 2 decomposition showed the highest performance of all, demonstrating that it was the optimal classification for the diagnosis of DMD.

Semantic classification of business images

NASA Astrophysics Data System (ADS)

Erol, Berna; Hull, Jonathan J.

2006-01-01

Digital cameras are becoming increasingly common for capturing information in business settings. In this paper, we describe a novel method for classifying images into the following semantic classes: document, whiteboard, business card, slide, and regular images. Our method is based on combining low-level image features, such as text color, layout, and handwriting features with high-level OCR output analysis. Several Support Vector Machine Classifiers are combined for multi-class classification of input images. The system yields 95% accuracy in classification.

Automatic generation of endocardial surface meshes with 1-to-1 correspondence from cine-MR images

NASA Astrophysics Data System (ADS)

Su, Yi; Teo, S.-K.; Lim, C. W.; Zhong, L.; Tan, R. S.

2015-03-01

In this work, we develop an automatic method to generate a set of 4D 1-to-1 corresponding surface meshes of the left ventricle (LV) endocardial surface which are motion registered over the whole cardiac cycle. These 4D meshes have 1- to-1 point correspondence over the entire set, and is suitable for advanced computational processing, such as shape analysis, motion analysis and finite element modelling. The inputs to the method are the set of 3D LV endocardial surface meshes of the different frames/phases of the cardiac cycle. Each of these meshes is reconstructed independently from border-delineated MR images and they have no correspondence in terms of number of vertices/points and mesh connectivity. To generate point correspondence, the first frame of the LV mesh model is used as a template to be matched to the shape of the meshes in the subsequent phases. There are two stages in the mesh correspondence process: (1) a coarse matching phase, and (2) a fine matching phase. In the coarse matching phase, an initial rough matching between the template and the target is achieved using a radial basis function (RBF) morphing process. The feature points on the template and target meshes are automatically identified using a 16-segment nomenclature of the LV. In the fine matching phase, a progressive mesh projection process is used to conform the rough estimate to fit the exact shape of the target. In addition, an optimization-based smoothing process is used to achieve superior mesh quality and continuous point motion.

Polypropylene Surgical Mesh Coated with Extracellular Matrix Mitigates the Host Foreign Body Response

PubMed Central

Wolf, Matthew T.; Carruthers, Christopher A.; Dearth, Christopher L.; Crapo, Peter M.; Huber, Alexander; Burnsed, Olivia A.; Londono, Ricardo; Johnson, Scott A.; Daly, Kerry A.; Stahl, Elizabeth C.; Freund, John M.; Medberry, Christopher J.; Carey, Lisa E.; Nieponice, Alejandro; Amoroso, Nicholas J.; Badylak, Stephen F.

2013-01-01

Surgical mesh devices composed of synthetic materials are commonly used for ventral hernia repair. These materials provide robust mechanical strength and are quickly incorporated into host tissue; factors which contribute to reduced hernia recurrence rates. However, such mesh devices cause a foreign body response with the associated complications of fibrosis and patient discomfort. In contrast, surgical mesh devices composed of naturally occurring extracellular matrix (ECM) are associated with constructive tissue remodeling, but lack the mechanical strength of synthetic materials. A method for applying a porcine dermal ECM hydrogel coating to a polypropylene mesh is described herein with the associated effects upon the host tissue response and biaxial mechanical behavior. Uncoated and ECM coated heavy-weight BARD™ Mesh were compared to the light-weight ULTRAPRO™ and BARD™ Soft Mesh devices in a rat partial thickness abdominal defect overlay model. The ECM coated mesh attenuated the pro-inflammatory response compared to all other devices, with a reduced cell accumulation and fewer foreign body giant cells. The ECM coating degraded by 35 days, and was replaced with loose connective tissue compared to the dense collagenous tissue associated with the uncoated polypropylene mesh device. Biaxial mechanical characterization showed that all of the mesh devices were of similar isotropic stiffness. Upon explantation, the light-weight mesh devices were more compliant than the coated or uncoated heavy-weight devices. The present study shows that an ECM coating alters the default host response to a polypropylene mesh, but not the mechanical properties in an acute in vivo abdominal repair model. PMID:23873846

Optimized Time-Gated Fluorescence Spectroscopy for the Classification and Recycling of Fluorescently Labeled Plastics.

PubMed

Fomin, Petr; Zhelondz, Dmitry; Kargel, Christian

2017-05-01

For the production of high-quality parts from recycled plastics, a very high purity of the plastic waste to be recycled is mandatory. The incorporation of fluorescent tracers ("markers") into plastics during the manufacturing process helps overcome typical problems of non-tracer based optical classification methods. Despite the unique emission spectra of fluorescent markers, the classification becomes difficult when the host plastics exhibit (strong) autofluorescence that spectrally overlaps the marker fluorescence. Increasing the marker concentration is not an option from an economic perspective and might also adversely affect the properties of the plastics. A measurement approach that suppresses the autofluorescence in the acquired signal is time-gated fluorescence spectroscopy (TGFS). Unfortunately, TGFS is associated with a lower signal-to-noise (S/N) ratio, which results in larger classification errors. In order to optimize the S/N ratio we investigate and validate the best TGFS parameters-derived from a model for the fluorescence signal-for plastics labeled with four specifically designed fluorescent markers. In this study we also demonstrate the implementation of TGFS on a measurement and classification prototype system and determine its performance. Mean values for a sensitivity of [Formula: see text] = 99.93% and precision [Formula: see text] = 99.80% were achieved, proving that a highly reliable classification of plastics can be achieved in practice.

Scene text detection via extremal region based double threshold convolutional network classification

PubMed Central

Zhu, Wei; Lou, Jing; Chen, Longtao; Xia, Qingyuan

2017-01-01

In this paper, we present a robust text detection approach in natural images which is based on region proposal mechanism. A powerful low-level detector named saliency enhanced-MSER extended from the widely-used MSER is proposed by incorporating saliency detection methods, which ensures a high recall rate. Given a natural image, character candidates are extracted from three channels in a perception-based illumination invariant color space by saliency-enhanced MSER algorithm. A discriminative convolutional neural network (CNN) is jointly trained with multi-level information including pixel-level and character-level information as character candidate classifier. Each image patch is classified as strong text, weak text and non-text by double threshold filtering instead of conventional one-step classification, leveraging confident scores obtained via CNN. To further prune non-text regions, we develop a recursive neighborhood search algorithm to track credible texts from weak text set. Finally, characters are grouped into text lines using heuristic features such as spatial location, size, color, and stroke width. We compare our approach with several state-of-the-art methods, and experiments show that our method achieves competitive performance on public datasets ICDAR 2011 and ICDAR 2013. PMID:28820891

Improved ALE mesh velocities for complex flows

DOE PAGES

Bakosi, Jozsef; Waltz, Jacob I.; Morgan, Nathaniel Ray

2017-05-31

A key choice in the development of arbitrary Lagrangian-Eulerian solution algorithms is how to move the computational mesh. The most common approaches are smoothing and relaxation techniques, or to compute a mesh velocity field that produces smooth mesh displacements. We present a method in which the mesh velocity is specified by the irrotational component of the fluid velocity as computed from a Helmholtz decomposition, and excess compression of mesh cells is treated through a noniterative, local spring-force model. This approach allows distinct and separate control over rotational and translational modes. In conclusion, the utility of the new mesh motion algorithmmore » is demonstrated on a number of 3D test problems, including problems that involve both shocks and significant amounts of vorticity.« less

Advances in Parallelization for Large Scale Oct-Tree Mesh Generation

NASA Technical Reports Server (NTRS)

O'Connell, Matthew; Karman, Steve L.

2015-01-01

Despite great advancements in the parallelization of numerical simulation codes over the last 20 years, it is still common to perform grid generation in serial. Generating large scale grids in serial often requires using special "grid generation" compute machines that can have more than ten times the memory of average machines. While some parallel mesh generation techniques have been proposed, generating very large meshes for LES or aeroacoustic simulations is still a challenging problem. An automated method for the parallel generation of very large scale off-body hierarchical meshes is presented here. This work enables large scale parallel generation of off-body meshes by using a novel combination of parallel grid generation techniques and a hybrid "top down" and "bottom up" oct-tree method. Meshes are generated using hardware commonly found in parallel compute clusters. The capability to generate very large meshes is demonstrated by the generation of off-body meshes surrounding complex aerospace geometries. Results are shown including a one billion cell mesh generated around a Predator Unmanned Aerial Vehicle geometry, which was generated on 64 processors in under 45 minutes.

Vaginal Approaches Using Synthetic Mesh to Treat Pelvic Organ Prolapse.

PubMed

Moon, Jei Won; Chae, Hee Dong

2016-02-01

Pelvic organ prolapse (POP) is a very common condition in elderly women. In women with POP, a sacrocolpopexy or a vaginal hysterectomy with anterior and posterior colporrhaphy has long been considered as the gold standard of treatment. However, in recent decades, the tendency to use a vaginal approach with mesh for POP surgery has been increasing. A vaginal approach using mesh has many advantages, such as its being less invasive than an abdominal approach and easier to do than a laparoscopic approach and its having a lower recurrence rate than a traditional approach. However, the advantages of a vaginal approach with mesh for POP surgery must be weighed against the disadvantages. Specific complications that have been reported when using mesh in POP procedures are mesh erosion, dyspareunia, hematomas, urinary incontinence and so on, and evidence supporting the use of transvaginal surgery with mesh is still lacking. Hence, surgeons should understand the details of the surgical pelvic anatomy, the various surgical techniques for POP surgery, including using mesh, and the possible side effects of using mesh.

Mesh refinement strategy for optimal control problems

NASA Astrophysics Data System (ADS)

Paiva, L. T.; Fontes, F. A. C. C.

2013-10-01

Direct methods are becoming the most used technique to solve nonlinear optimal control problems. Regular time meshes having equidistant spacing are frequently used. However, in some cases these meshes cannot cope accurately with nonlinear behavior. One way to improve the solution is to select a new mesh with a greater number of nodes. Another way, involves adaptive mesh refinement. In this case, the mesh nodes have non equidistant spacing which allow a non uniform nodes collocation. In the method presented in this paper, a time mesh refinement strategy based on the local error is developed. After computing a solution in a coarse mesh, the local error is evaluated, which gives information about the subintervals of time domain where refinement is needed. This procedure is repeated until the local error reaches a user-specified threshold. The technique is applied to solve the car-like vehicle problem aiming minimum consumption. The approach developed in this paper leads to results with greater accuracy and yet with lower overall computational time as compared to using a time meshes having equidistant spacing.

Water Penetration through a Superhydrophobic Mesh During a Drop Impact.

PubMed

Ryu, Seunggeol; Sen, Prosenjit; Nam, Youngsuk; Lee, Choongyeop

2017-01-06

When a water drop impacts a mesh having submillimeter pores, a part of the drop penetrates through the mesh if the impact velocity is sufficiently large. Here we show that different surface wettability, i.e., hydrophobicity and superhydrophobicity, leads to different water penetration dynamics on a mesh during drop impact. We show, despite the water repellence of a superhydrophobic surface, that water can penetrate a superhydrophobic mesh more easily (i.e., at a lower impact velocity) over a hydrophobic mesh via a penetration mechanism unique to a superhydrophobic mesh. On a superhydrophobic mesh, the water penetration can occur during the drop recoil stage, which appears at a lower impact velocity than the critical impact velocity for water penetration right upon impact. We propose that this unique water penetration on a superhydrophobic mesh can be attributed to the combination of the hydrodynamic focusing and the momentum transfer from the water drop when it is about to bounce off the surface, at which point the water drop retrieves most of its kinetic energy due to the negligible friction on superhydrophobic surfaces.

Latent Heat Thermal Energy Storage: Effect of Metallic Mesh Size on Storage Time and Capacity

NASA Astrophysics Data System (ADS)

Shuja, S. Z.; Yilbas, B. S.

2015-11-01

Use of metallic meshes in latent heat thermal storage system shortens the charging time (total melting of the phase change material), which is favorable in practical applications. In the present study, effect of metallic mesh size on the thermal characteristics of latent heat thermal storage system is investigated. Charging time is predicted for various mesh sizes, and the influence of the amount of mesh material on the charging capacity is examined. An experiment is carried out to validate the numerical predictions. It is found that predictions of the thermal characteristics of phase change material with presence of metallic meshes agree well with the experimental data. High conductivity of the metal meshes enables to transfer heat from the edges of the thermal system towards the phase change material while forming a conduction tree in the system. Increasing number of meshes in the thermal system reduces the charging time significantly due to increased rate of conduction heat transfer in the thermal storage system; however, increasing number of meshes lowers the latent heat storage capacity of the system.

Water Penetration through a Superhydrophobic Mesh During a Drop Impact

NASA Astrophysics Data System (ADS)

Ryu, Seunggeol; Sen, Prosenjit; Nam, Youngsuk; Lee, Choongyeop

2017-01-01

When a water drop impacts a mesh having submillimeter pores, a part of the drop penetrates through the mesh if the impact velocity is sufficiently large. Here we show that different surface wettability, i.e., hydrophobicity and superhydrophobicity, leads to different water penetration dynamics on a mesh during drop impact. We show, despite the water repellence of a superhydrophobic surface, that water can penetrate a superhydrophobic mesh more easily (i.e., at a lower impact velocity) over a hydrophobic mesh via a penetration mechanism unique to a superhydrophobic mesh. On a superhydrophobic mesh, the water penetration can occur during the drop recoil stage, which appears at a lower impact velocity than the critical impact velocity for water penetration right upon impact. We propose that this unique water penetration on a superhydrophobic mesh can be attributed to the combination of the hydrodynamic focusing and the momentum transfer from the water drop when it is about to bounce off the surface, at which point the water drop retrieves most of its kinetic energy due to the negligible friction on superhydrophobic surfaces.

Active learning for clinical text classification: is it better than random sampling?

PubMed

Figueroa, Rosa L; Zeng-Treitler, Qing; Ngo, Long H; Goryachev, Sergey; Wiechmann, Eduardo P

2012-01-01

This study explores active learning algorithms as a way to reduce the requirements for large training sets in medical text classification tasks. Three existing active learning algorithms (distance-based (DIST), diversity-based (DIV), and a combination of both (CMB)) were used to classify text from five datasets. The performance of these algorithms was compared to that of passive learning on the five datasets. We then conducted a novel investigation of the interaction between dataset characteristics and the performance results. Classification accuracy and area under receiver operating characteristics (ROC) curves for each algorithm at different sample sizes were generated. The performance of active learning algorithms was compared with that of passive learning using a weighted mean of paired differences. To determine why the performance varies on different datasets, we measured the diversity and uncertainty of each dataset using relative entropy and correlated the results with the performance differences. The DIST and CMB algorithms performed better than passive learning. With a statistical significance level set at 0.05, DIST outperformed passive learning in all five datasets, while CMB was found to be better than passive learning in four datasets. We found strong correlations between the dataset diversity and the DIV performance, as well as the dataset uncertainty and the performance of the DIST algorithm. For medical text classification, appropriate active learning algorithms can yield performance comparable to that of passive learning with considerably smaller training sets. In particular, our results suggest that DIV performs better on data with higher diversity and DIST on data with lower uncertainty.

Active learning for clinical text classification: is it better than random sampling?

PubMed Central

Figueroa, Rosa L; Ngo, Long H; Goryachev, Sergey; Wiechmann, Eduardo P

2012-01-01

Objective This study explores active learning algorithms as a way to reduce the requirements for large training sets in medical text classification tasks. Design Three existing active learning algorithms (distance-based (DIST), diversity-based (DIV), and a combination of both (CMB)) were used to classify text from five datasets. The performance of these algorithms was compared to that of passive learning on the five datasets. We then conducted a novel investigation of the interaction between dataset characteristics and the performance results. Measurements Classification accuracy and area under receiver operating characteristics (ROC) curves for each algorithm at different sample sizes were generated. The performance of active learning algorithms was compared with that of passive learning using a weighted mean of paired differences. To determine why the performance varies on different datasets, we measured the diversity and uncertainty of each dataset using relative entropy and correlated the results with the performance differences. Results The DIST and CMB algorithms performed better than passive learning. With a statistical significance level set at 0.05, DIST outperformed passive learning in all five datasets, while CMB was found to be better than passive learning in four datasets. We found strong correlations between the dataset diversity and the DIV performance, as well as the dataset uncertainty and the performance of the DIST algorithm. Conclusion For medical text classification, appropriate active learning algorithms can yield performance comparable to that of passive learning with considerably smaller training sets. In particular, our results suggest that DIV performs better on data with higher diversity and DIST on data with lower uncertainty. PMID:22707743

SU-F-J-218: Predicting Radiation-Induced Xerostomia by Dosimetrically Accounting for Daily Setup Uncertainty During Head and Neck IMRT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, S; Quon, H; McNutt, T

2016-06-15

Purpose: To determine if the accumulated parotid dosimetry using planning CT to daily CBCT deformation and dose re-calculation can predict for radiation-induced xerostomia. Methods: To track and dosimetrically account for the effects of anatomical changes on the parotid glands, we propagated physicians’ contours from planning CT to daily CBCT using a deformable registration with iterative CBCT intensity correction. A surface mesh for each OAR was created with the deformation applied to the mesh to obtain the deformed parotid volumes. Daily dose was computed on the deformed CT and accumulated to the last fraction. For both the accumulated and the plannedmore » parotid dosimetry, we tested the prediction power of different dosimetric parameters including D90, D50, D10, mean, standard deviation, min/max dose to the combined parotids and patient age to severe xerostomia (NCI-CTCAE grade≥2 at 6 mo follow-up). We also tested the dosimetry to parotid sub-volumes. Three classification algorithms, random tree, support vector machine, and logistic regression were tested to predict severe xerostomia using a leave-one-out validation approach. Results: We tested our prediction model on 35 HN IMRT cases. Parameters from the accumulated dosimetry model demonstrated an 89% accuracy for predicting severe xerostomia. Compared to the planning dosimetry, the accumulated dose consistently demonstrated higher prediction power with all three classification algorithms, including 11%, 5% and 30% higher accuracy, sensitivity and specificity, respectively. Geometric division of the combined parotid glands into superior-inferior regions demonstrated ∼5% increased accuracy than the whole volume. The most influential ranked features include age, mean accumulated dose of the submandibular glands and the accumulated D90 of the superior parotid glands. Conclusion: We demonstrated that the accumulated parotid dosimetry using CT-CBCT registration and dose re-calculation more accurately predicts for severe xerostomia and that the superior portion of the parotid glands may be particularly important in predicting for severe xerostomia. This work was supported in part by NIH/NCI under grant R42CA137886 and in part by Toshiba big data research project funds.« less

Transrectal Mesh Erosion Requiring Bowel Resection.

PubMed

Kemp, Marta Maria; Slim, Karem; Rabischong, Benoît; Bourdel, Nicolas; Canis, Michel; Botchorishvili, Revaz

To report a case of a transrectal mesh erosion as complication of laparoscopic promontofixation with mesh repair, necessitating bowel resection and subsequent surgical interventions. Sacrocolpopexy has become a standard procedure for vaginal vault prolapse [1], and the laparoscopic approach has gained popularity owing to more rapid recovery and less morbidity [2,3]. Mesh erosion is a well-known complication of surgical treatment for prolapse as reported in several negative evaluations, including a report from the US Food and Drug Administration in 2011 [4]. Mesh complications are more common after surgeries via the vaginal approach [5]; nonetheless, the incidence of vaginal mesh erosion after laparoscopic procedures is as high as 9% [6]. The incidence of transrectal mesh exposure after laparoscopic ventral rectopexy is roughly 1% [7]. The diagnosis may be delayed because of its rarity and variable presentation. In addition, polyester meshes, such as the mesh used in this case, carry a higher risk of exposure [8]. A 57-year-old woman experiencing genital prolapse, with the cervix classified as +3 according to the Pelvic Organ Prolapse Quantification system, underwent laparoscopic standard sacrocolpopexy using polyester mesh. Subtotal hysterectomy and bilateral adnexectomy were performed concomitantly. A 3-year follow-up consultation demonstrated no signs or symptoms of erosion of any type. At 7 years after the surgery, however, the patient presented with rectal discharge, diagnosed as infectious rectocolitis with the isolation of Clostridium difficile. She underwent a total of 5 repair surgeries in a period of 4 months, including transrectal resection of exposed mesh, laparoscopic ablation of mesh with digestive resection, exploratory laparoscopy with abscess drainage, and exploratory laparoscopy with ablation of residual mesh and transverse colostomy. She recovered well after the last intervention, exhibiting no signs of vaginal or rectal fistula and no recurrence of pelvic floor descent. Her intestinal transit was reestablished, and she was satisfied with the treatment. None of the studies that represent the specific female population submitted to laparoscopic promontofixation with transrectal mesh erosion describe the need for more than one intervention or digestive resection [9-12]. Physicians dealing with patients submitted to pelvic reconstructive surgeries with mesh placement should be aware of transrectal and other nonvaginal erosions of mesh, even being rare events. Moreover, they should perform an active search for unusual gynecologic and anorectal signs and symptoms. Most importantly, patients undergoing mesh repair procedures must be warned of the risks of the surgery, including the possibility of several subsequent interventions. Copyright © 2017 AAGL. Published by Elsevier Inc. All rights reserved.

Automated ancillary cancer history classification for mesothelioma patients from free-text clinical reports

PubMed Central

Wilson, Richard A.; Chapman, Wendy W.; DeFries, Shawn J.; Becich, Michael J.; Chapman, Brian E.

2010-01-01

Background: Clinical records are often unstructured, free-text documents that create information extraction challenges and costs. Healthcare delivery and research organizations, such as the National Mesothelioma Virtual Bank, require the aggregation of both structured and unstructured data types. Natural language processing offers techniques for automatically extracting information from unstructured, free-text documents. Methods: Five hundred and eight history and physical reports from mesothelioma patients were split into development (208) and test sets (300). A reference standard was developed and each report was annotated by experts with regard to the patient’s personal history of ancillary cancer and family history of any cancer. The Hx application was developed to process reports, extract relevant features, perform reference resolution and classify them with regard to cancer history. Two methods, Dynamic-Window and ConText, for extracting information were evaluated. Hx’s classification responses using each of the two methods were measured against the reference standard. The average Cohen’s weighted kappa served as the human benchmark in evaluating the system. Results: Hx had a high overall accuracy, with each method, scoring 96.2%. F-measures using the Dynamic-Window and ConText methods were 91.8% and 91.6%, which were comparable to the human benchmark of 92.8%. For the personal history classification, Dynamic-Window scored highest with 89.2% and for the family history classification, ConText scored highest with 97.6%, in which both methods were comparable to the human benchmark of 88.3% and 97.2%, respectively. Conclusion: We evaluated an automated application’s performance in classifying a mesothelioma patient’s personal and family history of cancer from clinical reports. To do so, the Hx application must process reports, identify cancer concepts, distinguish the known mesothelioma from ancillary cancers, recognize negation, perform reference resolution and determine the experiencer. Results indicated that both information extraction methods tested were dependant on the domain-specific lexicon and negation extraction. We showed that the more general method, ConText, performed as well as our task-specific method. Although Dynamic- Window could be modified to retrieve other concepts, ConText is more robust and performs better on inconclusive concepts. Hx could greatly improve and expedite the process of extracting data from free-text, clinical records for a variety of research or healthcare delivery organizations. PMID:21031012

Android Malware Classification Using K-Means Clustering Algorithm

NASA Astrophysics Data System (ADS)

Hamid, Isredza Rahmi A.; Syafiqah Khalid, Nur; Azma Abdullah, Nurul; Rahman, Nurul Hidayah Ab; Chai Wen, Chuah

2017-08-01

Malware was designed to gain access or damage a computer system without user notice. Besides, attacker exploits malware to commit crime or fraud. This paper proposed Android malware classification approach based on K-Means clustering algorithm. We evaluate the proposed model in terms of accuracy using machine learning algorithms. Two datasets were selected to demonstrate the practicing of K-Means clustering algorithms that are Virus Total and Malgenome dataset. We classify the Android malware into three clusters which are ransomware, scareware and goodware. Nine features were considered for each types of dataset such as Lock Detected, Text Detected, Text Score, Encryption Detected, Threat, Porn, Law, Copyright and Moneypak. We used IBM SPSS Statistic software for data classification and WEKA tools to evaluate the built cluster. The proposed K-Means clustering algorithm shows promising result with high accuracy when tested using Random Forest algorithm.

Updates to Simulation of a Single-Element Lean-Direct Injection Combustor Using Arbitary Polyhedral Meshes

NASA Technical Reports Server (NTRS)

Wey, Thomas; Liu, Nan-Suey

2015-01-01

This paper summarizes the procedures of (1) generating control volumes anchored at the nodes of a mesh; and (2) generating staggered control volumes via mesh reconstructions, in terms of either mesh realignment or mesh refinement, as well as presents sample results from their applications to the numerical solution of a single-element LDI combustor using a releasable edition of the National Combustion Code (NCC).

In-memory integration of existing software components for parallel adaptive unstructured mesh workflows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Cameron W.; Granzow, Brian; Diamond, Gerrett

Unstructured mesh methods, like finite elements and finite volumes, support the effective analysis of complex physical behaviors modeled by partial differential equations over general threedimensional domains. The most reliable and efficient methods apply adaptive procedures with a-posteriori error estimators that indicate where and how the mesh is to be modified. Although adaptive meshes can have two to three orders of magnitude fewer elements than a more uniform mesh for the same level of accuracy, there are many complex simulations where the meshes required are so large that they can only be solved on massively parallel systems.

In-memory integration of existing software components for parallel adaptive unstructured mesh workflows

DOE PAGES

Smith, Cameron W.; Granzow, Brian; Diamond, Gerrett; ...

2017-01-01

Unstructured mesh methods, like finite elements and finite volumes, support the effective analysis of complex physical behaviors modeled by partial differential equations over general threedimensional domains. The most reliable and efficient methods apply adaptive procedures with a-posteriori error estimators that indicate where and how the mesh is to be modified. Although adaptive meshes can have two to three orders of magnitude fewer elements than a more uniform mesh for the same level of accuracy, there are many complex simulations where the meshes required are so large that they can only be solved on massively parallel systems.

Implementation of tetrahedral-mesh geometry in Monte Carlo radiation transport code PHITS

NASA Astrophysics Data System (ADS)

Furuta, Takuya; Sato, Tatsuhiko; Han, Min Cheol; Yeom, Yeon Soo; Kim, Chan Hyeong; Brown, Justin L.; Bolch, Wesley E.

2017-06-01

A new function to treat tetrahedral-mesh geometry was implemented in the particle and heavy ion transport code systems. To accelerate the computational speed in the transport process, an original algorithm was introduced to initially prepare decomposition maps for the container box of the tetrahedral-mesh geometry. The computational performance was tested by conducting radiation transport simulations of 100 MeV protons and 1 MeV photons in a water phantom represented by tetrahedral mesh. The simulation was repeated with varying number of meshes and the required computational times were then compared with those of the conventional voxel representation. Our results show that the computational costs for each boundary crossing of the region mesh are essentially equivalent for both representations. This study suggests that the tetrahedral-mesh representation offers not only a flexible description of the transport geometry but also improvement of computational efficiency for the radiation transport. Due to the adaptability of tetrahedrons in both size and shape, dosimetrically equivalent objects can be represented by tetrahedrons with a much fewer number of meshes as compared its voxelized representation. Our study additionally included dosimetric calculations using a computational human phantom. A significant acceleration of the computational speed, about 4 times, was confirmed by the adoption of a tetrahedral mesh over the traditional voxel mesh geometry.

Implementation of tetrahedral-mesh geometry in Monte Carlo radiation transport code PHITS.

PubMed

Furuta, Takuya; Sato, Tatsuhiko; Han, Min Cheol; Yeom, Yeon Soo; Kim, Chan Hyeong; Brown, Justin L; Bolch, Wesley E

2017-06-21

A new function to treat tetrahedral-mesh geometry was implemented in the particle and heavy ion transport code systems. To accelerate the computational speed in the transport process, an original algorithm was introduced to initially prepare decomposition maps for the container box of the tetrahedral-mesh geometry. The computational performance was tested by conducting radiation transport simulations of 100 MeV protons and 1 MeV photons in a water phantom represented by tetrahedral mesh. The simulation was repeated with varying number of meshes and the required computational times were then compared with those of the conventional voxel representation. Our results show that the computational costs for each boundary crossing of the region mesh are essentially equivalent for both representations. This study suggests that the tetrahedral-mesh representation offers not only a flexible description of the transport geometry but also improvement of computational efficiency for the radiation transport. Due to the adaptability of tetrahedrons in both size and shape, dosimetrically equivalent objects can be represented by tetrahedrons with a much fewer number of meshes as compared its voxelized representation. Our study additionally included dosimetric calculations using a computational human phantom. A significant acceleration of the computational speed, about 4 times, was confirmed by the adoption of a tetrahedral mesh over the traditional voxel mesh geometry.

A method to generate conformal finite-element meshes from 3D measurements of microstructurally small fatigue-crack propagation [A method to generate conformal finite-element meshes from 3D measurements of microstructurally small fatigue-crack propagation: 3D Meshes of Microstructurally Small Crack Growth

DOE PAGES

Spear, Ashley D.; Hochhalter, Jacob D.; Cerrone, Albert R.; ...

2016-04-27

In an effort to reproduce computationally the observed evolution of microstructurally small fatigue cracks (MSFCs), a method is presented for generating conformal, finite-element (FE), volume meshes from 3D measurements of MSFC propagation. The resulting volume meshes contain traction-free surfaces that conform to incrementally measured 3D crack shapes. Grain morphologies measured using near-field high-energy X-ray diffraction microscopy are also represented within the FE volume meshes. Proof-of-concept simulations are performed to demonstrate the utility of the mesh-generation method. The proof-of-concept simulations employ a crystal-plasticity constitutive model and are performed using the conformal FE meshes corresponding to successive crack-growth increments. Although the simulationsmore » for each crack increment are currently independent of one another, they need not be, and transfer of material-state information among successive crack-increment meshes is discussed. The mesh-generation method was developed using post-mortem measurements, yet it is general enough that it can be applied to in-situ measurements of 3D MSFC propagation.« less

A method to generate conformal finite-element meshes from 3D measurements of microstructurally small fatigue-crack propagation [A method to generate conformal finite-element meshes from 3D measurements of microstructurally small fatigue-crack propagation: 3D Meshes of Microstructurally Small Crack Growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spear, Ashley D.; Hochhalter, Jacob D.; Cerrone, Albert R.

In an effort to reproduce computationally the observed evolution of microstructurally small fatigue cracks (MSFCs), a method is presented for generating conformal, finite-element (FE), volume meshes from 3D measurements of MSFC propagation. The resulting volume meshes contain traction-free surfaces that conform to incrementally measured 3D crack shapes. Grain morphologies measured using near-field high-energy X-ray diffraction microscopy are also represented within the FE volume meshes. Proof-of-concept simulations are performed to demonstrate the utility of the mesh-generation method. The proof-of-concept simulations employ a crystal-plasticity constitutive model and are performed using the conformal FE meshes corresponding to successive crack-growth increments. Although the simulationsmore » for each crack increment are currently independent of one another, they need not be, and transfer of material-state information among successive crack-increment meshes is discussed. The mesh-generation method was developed using post-mortem measurements, yet it is general enough that it can be applied to in-situ measurements of 3D MSFC propagation.« less

Effect of Codend Circumference on the Size Selection of Square-Mesh Codends in Trawl Fisheries

PubMed Central

De Carlo, Francesco; Lucchetti, Alessandro

2016-01-01

It is well established that increasing mesh number in the circumference of a diamond-mesh trawl codend can reduce size selection for round fish, whereas selection for flat fish species is unaffected. This effect has also been documented in Mediterranean trawl fisheries. In contrast, no information is available with regard to the effect of increasing mesh number in the circumference of square-mesh codends on the size selection of round fish and flat fish species. A field study was devised to bridge this gap and formulate proposals aimed at improving trawl fishery management. Size selection data were collected for a round fish species, red mullet (Mullus barbatus), and two flat fish species, Mediterranean scaldfish (Arnoglossus laterna) and solenette (Buglossidium luteum). Fishing trials were conducted in the Adriatic Sea (Central Mediterranean) using three square-mesh codends that differed only in mesh number around the circumference. Results demonstrated that increasing the number of meshes from 107 to 213 reduced the 50% retention length (L50) for red mullet by 2.5 cm but did not affect size selection for the two flat fish species. In some fisheries, regulatory provisions regarding the number of meshes in the circumference should therefore be carefully considered both for diamond- and square-mesh codends. PMID:27472058

Commercial materials as cathode for hydrogen production in microbial electrolysis cell.

PubMed

Farhangi, Sara; Ebrahimi, Sirous; Niasar, Mojtaba Shariati

2014-10-01

The use of commercial electrodes as cathodes in a single-chamber microbial electrolysis cell has been investigated. The cell was operated in sequencing batch mode and the performance of the electrodes was compared with carbon cloth containing 0.5 mg Pt cm(-2). Overall H2 recovery [Formula: see text] was 66.7 ± 1.4, 58.7 ± 1.1 and 55.5 ± 1.5 % for Pt/CC, Ni and Ti mesh electrodes, respectively. Columbic efficiencies of the three cathodes were in the same range (74.8 ± 1.5, 77.6 ± 1.7 and 75.7 ± 1.2 % for Pt/CC, Ni and Ti mesh electrodes, respectively). A similar performance for the three cathodes under near-neutral pH and ambient temperature was obtained. The commercial electrodes are much cheaper than carbon cloth containing Pt. Low cost and good performance of these electrodes suggest they are suitable cathode materials for large scale application.

Mesh for prolapse surgery: Why the fuss?

PubMed

Rajshekhar, Smita; Mukhopadhyay, Sambit; Klinge, Uwe

2015-06-01

Pelvic organ prolapse is a common gynaecological problem. Surgical techniques to repair prolapse have been constantly evolving to reduce the recurrence of prolapse and need for reoperation. Grafts made of synthetic and biological materials became popular in the last decade as they were intended to provide extra support to native tissue repairs. However, serious complications related to use of synthetic meshes have been reported and there is increasing medico-legal concern about mesh use in prolapse surgery. Some mesh products already have been withdrawn from the market and the FDA has introduced stricter surveillance of new and existing products. Large randomized studies comparing mesh with non-mesh procedures are lacking which creates uncertainty for the surgeon and their patients.The small cohorts of the RCTs available with short follow-up periods just allow the conclusion that the mesh repair can be helpful in the short to medium term but unfortunately are not able to prove safety for all patients. In particular, current clinical reports cannot define for which indication what material may be superior compared to non-mesh repair.Quality control through long-term individual and national mesh registries is needed to keep a record of all surgeons using mesh and all devices being used, monitoring their effectiveness and safety data. Meshes with better biocompatibility designed specifically for use in vaginal surgery may provide superior clinical results, where the reduction of complications may allow a wider range of indications. © The Author(s) 2015.

Mechanical behaviour of synthetic surgical meshes: finite element simulation of the herniated abdominal wall.

PubMed

Hernández-Gascón, B; Peña, E; Melero, H; Pascual, G; Doblaré, M; Ginebra, M P; Bellón, J M; Calvo, B

2011-11-01

The material properties of meshes used in hernia surgery contribute to the overall mechanical behaviour of the repaired abdominal wall. The mechanical response of a surgical mesh has to be defined since the haphazard orientation of an anisotropic mesh can lead to inconsistent surgical outcomes. This study was designed to characterize the mechanical behaviour of three surgical meshes (Surgipro®, Optilene® and Infinit®) and to describe a mechanical constitutive law that accurately reproduces the experimental results. Finally, through finite element simulation, the behaviour of the abdominal wall was modelled before and after surgical mesh implant. Uniaxial loading of mesh samples in two perpendicular directions revealed the isotropic response of Surgipro® and the anisotropic behaviour of Optilene® and Infinit®. A phenomenological constitutive law was used to reproduce the measured experimental curves. To analyze the mechanical effect of the meshes once implanted in the abdomen, finite element simulation of the healthy and partially herniated repaired rabbit abdominal wall served to reproduce wall behaviour before and after mesh implant. In all cases, maximal displacements were lower and maximal principal stresses higher in the implanted abdomen than the intact wall model. Despite the fact that no mesh showed a behaviour that perfectly matched that of abdominal muscle, the Infinit® mesh was able to best comply with the biomechanics of the abdominal wall. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Early biocompatibility of crosslinked and non-crosslinked biologic meshes in a porcine model of ventral hernia repair.

PubMed

Melman, L; Jenkins, E D; Hamilton, N A; Bender, L C; Brodt, M D; Deeken, C R; Greco, S C; Frisella, M M; Matthews, B D

2011-04-01

Biologic meshes have unique physical properties as a result of manufacturing techniques such as decellularization, crosslinking, and sterilization. The purpose of this study is to directly compare the biocompatibility profiles of five different biologic meshes, AlloDerm(®) (non-crosslinked human dermal matrix), PeriGuard(®) (crosslinked bovine pericardium), Permacol(®) (crosslinked porcine dermal matrix), Strattice(®) (non-crosslinked porcine dermal matrix), and Veritas(®) (non-crosslinked bovine pericardium), using a porcine model of ventral hernia repair. Full-thickness fascial defects were created in 20 Yucatan minipigs and repaired with the retromuscular placement of biologic mesh 3 weeks later. Animals were euthanized at 1 month and the repair sites were subjected to tensile testing and histologic analysis. Samples of unimplanted (de novo) meshes and native porcine abdominal wall were also analyzed for their mechanical properties. There were no significant differences in the biomechanical characteristics between any of the mesh-repaired sites at 1 month postimplantation or between the native porcine abdominal wall without implanted mesh and the mesh-repaired sites (P > 0.05 for all comparisons). Histologically, non-crosslinked materials exhibited greater cellular infiltration, extracellular matrix (ECM) deposition, and neovascularization compared to crosslinked meshes. While crosslinking differentiates biologic meshes with regard to cellular infiltration, ECM deposition, scaffold degradation, and neovascularization, the integrity and strength of the repair site at 1 month is not significantly impacted by crosslinking or by the de novo strength/stiffness of the mesh.

Streaming simplification of tetrahedral meshes.

PubMed

Vo, Huy T; Callahan, Steven P; Lindstrom, Peter; Pascucci, Valerio; Silva, Cláudio T

2007-01-01

Unstructured tetrahedral meshes are commonly used in scientific computing to represent scalar, vector, and tensor fields in three dimensions. Visualization of these meshes can be difficult to perform interactively due to their size and complexity. By reducing the size of the data, we can accomplish real-time visualization necessary for scientific analysis. We propose a two-step approach for streaming simplification of large tetrahedral meshes. Our algorithm arranges the data on disk in a streaming, I/O-efficient format that allows coherent access to the tetrahedral cells. A quadric-based simplification is sequentially performed on small portions of the mesh in-core. Our output is a coherent streaming mesh which facilitates future processing. Our technique is fast, produces high quality approximations, and operates out-of-core to process meshes too large for main memory.

Bluetooth Low Energy Mesh Networks: A Survey.

PubMed

Darroudi, Seyed Mahdi; Gomez, Carles

2017-06-22

Bluetooth Low Energy (BLE) has gained significant momentum. However, the original design of BLE focused on star topology networking, which limits network coverage range and precludes end-to-end path diversity. In contrast, other competing technologies overcome such constraints by supporting the mesh network topology. For these reasons, academia, industry, and standards development organizations have been designing solutions to enable BLE mesh networks. Nevertheless, the literature lacks a consolidated view on this emerging area. This paper comprehensively surveys state of the art BLE mesh networking. We first provide a taxonomy of BLE mesh network solutions. We then review the solutions, describing the variety of approaches that leverage existing BLE functionality to enable BLE mesh networks. We identify crucial aspects of BLE mesh network solutions and discuss their advantages and drawbacks. Finally, we highlight currently open issues.

Impact of the 2011 FDA transvaginal mesh safety update on AUGS members' use of synthetic mesh and biologic grafts in pelvic reconstructive surgery.

PubMed

Clemons, Jeffrey L; Weinstein, Milena; Guess, Marsha K; Alperin, Marianna; Moalli, Pamela; Gregory, William Thomas; Lukacz, Emily S; Sung, Vivian W; Chen, Bertha H; Bradley, Catherine S

2013-01-01

To describe the frequency of use and recent change in use of synthetic mesh and biologic grafts in pelvic organ prolapse (POP) and stress urinary incontinence surgery by American Urogynecology Society (AUGS) members. An electronic survey of AUGS members was conducted between December 2011 and January 2012. Frequency of graft use in POP (overall and by transvaginal and transabdominal approaches) and stress urinary incontinence surgery was queried relative to the timing of the 2011 Food and Drug Administration (FDA) safety update. Rates of materials' use before and after the statement were compared using Wilcoxon signed rank test. Fifty-three percent (507/962) of AUGS members responded and were included in analysis; 79% were urogynecologists. Before the FDA warning, in POP surgery, most (90%) used synthetic mesh and fewer (34%) used biologic grafts; 99% used synthetic mesh slings. After the FDA statement, respondents reported an overall decrease in the percent of POP cases in which they used synthetic mesh (P < 0.001) but no change in biologic graft use for POP (P = 0.37) or synthetic mesh sling use (P = 0.10). Specifically, transvaginal mesh use decreased: 40% reported decreased use and 12% stopped use. However, transvaginal mesh was still used by 61% of respondents in at least some cases. No change (62%) or increased use (12%) of mesh was reported for transabdominal POP procedures. Synthetic mesh use in transvaginal POP surgery decreased after the 2011 FDA safety update, but synthetic mesh use for transabdominal POP repair and sling procedures and overall biologic graft use in POP surgery did not decrease.

Monte Carlo design of optimal wire mesh collimator for breast tumor imaging process

NASA Astrophysics Data System (ADS)

Saad, W. H. M.; Roslan, R. E.; Mahdi, M. A.; Choong, W.-S.; Saion, E.; Saripan, M. I.

2011-08-01

This paper presents the modeling of breast tumor imaging process using wire mesh collimator gamma camera. Previous studies showed that the wire mesh collimator has a potential to improve the sensitivity of the tumor detection. In this paper, we extend our research significantly, to find an optimal configuration of the wire mesh collimator specifically for semi-compressed breast tumor detection, by looking into four major factors: weight, sensitivity, spatial resolution and tumor contrast. The numbers of layers in the wire mesh collimator is varied to optimize the collimator design. The statistical variations of the results are studied by simulating multiple realizations for each experiment using different starting random numbers. All the simulation environments are modeled using Monte Carlo N-Particle Code (MCNP). The quality of the detection is measured directly by comparing the sensitivity, spatial resolution and tumor contrast of the images produced by the wire mesh collimator and benchmarked that with a standard multihole collimator. The proposed optimal configuration of the wire mesh collimator is optimized by selecting the number of layers in wire mesh collimator, where the tumor contrast shows a relatively comparable value to the multihole collimator, when it is tested with uniformly semi-compressed breast phantom. The wire mesh collimator showed higher number of sensitivity because of its loose arrangement while the spatial resolution of wire mesh collimator does not shows much different compared to the multihole collimator. With a relatively good tumor contrast and spatial resolution, and increased in sensitivity, a new proposed wire mesh collimator gives a significant improvement in the wire mesh collimator design for breast cancer imaging process. The proposed collimator configuration is reduced to 44.09% from the total multihole collimator weight.

Mesh refinement in finite element analysis by minimization of the stiffness matrix trace

NASA Technical Reports Server (NTRS)

Kittur, Madan G.; Huston, Ronald L.

1989-01-01

Most finite element packages provide means to generate meshes automatically. However, the user is usually confronted with the problem of not knowing whether the mesh generated is appropriate for the problem at hand. Since the accuracy of the finite element results is mesh dependent, mesh selection forms a very important step in the analysis. Indeed, in accurate analyses, meshes need to be refined or rezoned until the solution converges to a value so that the error is below a predetermined tolerance. A-posteriori methods use error indicators, developed by using the theory of interpolation and approximation theory, for mesh refinements. Some use other criterions, such as strain energy density variation and stress contours for example, to obtain near optimal meshes. Although these methods are adaptive, they are expensive. Alternatively, a priori methods, until now available, use geometrical parameters, for example, element aspect ratio. Therefore, they are not adaptive by nature. An adaptive a-priori method is developed. The criterion is that the minimization of the trace of the stiffness matrix with respect to the nodal coordinates, leads to a minimization of the potential energy, and as a consequence provide a good starting mesh. In a few examples the method is shown to provide the optimal mesh. The method is also shown to be relatively simple and amenable to development of computer algorithms. When the procedure is used in conjunction with a-posteriori methods of grid refinement, it is shown that fewer refinement iterations and fewer degrees of freedom are required for convergence as opposed to when the procedure is not used. The mesh obtained is shown to have uniform distribution of stiffness among the nodes and elements which, as a consequence, leads to uniform error distribution. Thus the mesh obtained meets the optimality criterion of uniform error distribution.

Mesh size effects on assessments of planktonic hydrozoan abundance and assemblage structure

NASA Astrophysics Data System (ADS)

Nogueira Júnior, Miodeli; Pukanski, Luis Eduardo de M.; Souza-Conceição, José M.

2015-04-01

The choice of appropriate mesh-size is paramount to accurately quantify planktonic assemblages, however there is no such information available for hydrozoans. Here planktonic hydrozoan abundance and assemblage structure were compared using 200 and 500 μm meshes at Babitonga estuary (S Brazil), throughout a year cycle. Species richness and Shannon-Wiener diversity were higher in the 200 μm mesh, while evenness was typically higher in the 500 μm. Assemblage structure was significantly different between meshes (PERMANOVA, P < 0.05; n = 72 pairs of samples) both regarding taxa and size composition. These discrepancies are due to significant underestimation of small hydromedusae by the coarse mesh, like Obelia spp., young Liriope tetraphylla, Podocoryna loyola and others. Yet, larger taxa like Eucheilota maculata and adult L. tetraphylla were more abundant in the coarse mesh on some occasions and others such as Blackfordia virginica and Muggiaea kochi were similarly represented in both meshes. Overall collection efficiency of the coarse mesh (CE500) was 14.4%, with monthly averages between 1.6% and 43.0%, in July (winter) and January (summer) respectively. Differences between the meshes were size-dependent; CE500 was ~ 0.3% for hydrozoans sizing < 0.5 mm, ~ 21% for those between 1 and 2 mm, ~ 56% for those between 2 and 4 mm, and nearly 100% for larger ones, reaching up to 312% for hydrozoans > 8 mm in October. These results suggest that both meshes have their drawbacks and the best choice would depend on the objectives of each study. Nevertheless species richness, total abundances and most taxa were better represented by the 200 μm mesh, suggesting that it is more appropriate to quantitatively sample planktonic hydrozoan assemblages.

Does expanded polytetrafluoroethylene mesh really shrink after laparoscopic ventral hernia repair?

PubMed

Carter, P R; LeBlanc, K A; Hausmann, M G; Whitaker, J M; Rhynes, V K; Kleinpeter, K P; Allain, B W

2012-06-01

The shrinkage of mesh has been cited as a possible explanation for hernia recurrence. Expanded polytetrafluoroethylene (ePTFE) is unique in that it can be visualized on computed tomography (CT). Some animal studies have shown a greater than 40% rate of contraction of ePTFE; however, very few human studies have been performed. A total of 815 laparoscopic incisional/ventral hernia (LIVH) repairs were performed by a single surgical group. DualMesh Plus (ePTFE) (WL Gore & Associates, Newark, DE) was placed in the majority of these patients using both transfascial sutures and tack fixation. Fifty-eight patients had postoperative CTs of the abdomen and pelvis with ePTFE and known transverse diameter of the implanted mesh. The prosthesis was measured on the CT using the AquariusNet software program (TeraRecon, San Mateo, CA), which outlines the mesh and calculates the total length. Data were collected regarding the original mesh size, known linear dimension of mesh, seroma formation, and time interval since mesh implantation in months. The mean shrinkage rate was 6.7%. The duration of implantation ranged from 6 weeks to 78 months, with a median of 15 months. Seroma was seen in 8.6% (5) of patients. No relationship was identified between the percentage of shrinkage and the original mesh size (P = 0.78), duration of time implanted (P = 0.57), or seroma formation (P = 0.074). In 27.5% (16) of patients, no shrinkage of mesh was identified. Of the patients who did experience mesh shrinkage, the range of shrinkage was 2.6-25%. Our results are markedly different from animal studies and show that ePTFE has minimal shrinkage after LIVH repair. The use of transfascial sutures in addition to tack fixation may have an implication on the mesh contraction rates.

Defining patients' knowledge and perceptions of vaginal mesh surgery.

PubMed

Brown, Lindsay K; Fenner, Dee E; Berger, Mitchell B; Delancey, John O L; Morgan, Daniel M; Patel, Divya A; Schimpf, Megan O

2013-01-01

Given recent government investigations and media coverage of the controversy regarding mesh surgery, we sought to define patients' knowledge and perceptions of vaginal mesh surgery. An anonymous survey was distributed to a convenience sample of new patients at urogynecology and female urology clinics at a single medical center during April to June 2012. The survey assessed patients' demographics, information sources, and beliefs and concerns regarding mesh surgery. The Fisher's exact test was used to identify predictors of patients' beliefs regarding mesh. Logistic and linear regressions were used to identify predictors of aversion to surgery and higher concern regarding future surgery. One hundred sixty-four women completed the survey; 62.2% (102/164) indicated knowledge of mesh surgery for prolapse and/or incontinence and were included in subsequent analyses. The mean ± SD age was 58.0 ± 12.5 years, and 24.5% reported prior mesh surgery. The most common information source was television commercials (57.8%); only 23.5% of the women reported receiving information from a medical professional. Participants indicated the following regarding vaginal mesh: class-action lawsuit in progress (55/102 [54.0%]), causes pain (47/102 [47.1%]), possibility of rejection (35/102 [34.3%]), can cause bleeding and become exposed vaginally (30/102 [29.4%]), and should be removed owing to recall (28/102 [27.5%]). Of these women, 22.1% (19/86) indicated they would not consider mesh surgery. On multivariable logistic regression, level of concern, information from friends/family, and knowledge of class-action lawsuit predicted aversion to mesh surgery. Nearly two thirds of new patients had knowledge of vaginal mesh surgery. We identified considerable misinformation and aversion to future mesh surgery among these women.

Electrical characteristic of the titanium mesh electrode for transcutaneous intrabody communication to monitor implantable artificial organs.

PubMed

Okamoto, Eiji; Kikuchi, Sakiko; Mitamura, Yoshinori

2016-09-01

We have developed a tissue-inducing electrode using titanium mesh to obtain mechanically and electrically stable contact with the tissue for a new transcutaneous communication system using the human body as a conductive medium. In this study, we investigated the electrical properties of the titanium mesh electrode by measuring electrode-tissue interface resistance in vivo. The titanium mesh electrode (Hi-Lex Co., Zellez, Hyogo, Japan) consisted of titanium fibers (diameter of 50 μm), and it has an average pore size of 200 μm and 87 % porosity. The titanium mesh electrode has a diameter of 5 mm and thickness of 1.5 mm. Three titanium mesh electrodes were implanted separately into the dorsal region of the rat. We measured the electrode-electrode impedance using an LCR meter for 12 weeks, and we calculated the tissue resistivity and electrode-tissue interface resistance. The electrode-tissue interface resistance of the titanium mesh electrode decreased slightly until the third POD and then continuously increased to 75 Ω. The electrode-tissue interface resistance of the titanium mesh electrode is stable and it has lower electrode-tissue interface resistance than that of a titanium disk electrode. The extracted titanium mesh electrode after 12 weeks implantation was fixed in 10 % buffered formalin solution and stained with hematoxylin-eosin. Light microscopic observation showed that the titanium mesh electrode was filled with connective tissue, inflammatory cells and fibroblasts with some capillaries in the pores of the titanium mesh. The results indicate that the titanium mesh electrode is a promising electrode for the new transcutaneous communication system.

Query Refinement: Negation Detection and Proximity Learning Georgetown at TREC 2014 Clinical Decision Support Track

DTIC Science & Technology

2014-11-01

created to serve as idealized representations of actual medical records, and include information such as medical history , current symptoms, diagnosis...NLM Medical Text Indexer (MTI).3 MeSH, or Medical Subject Headings, are terminology used by the NLM to index articles, catalog books, and searching...MeSH- indexed databases such as PubMed. However, since many medical conditions may be expressed in varying terminology , a single representation of a

Constructing and validating readability models: the method of integrating multilevel linguistic features with machine learning.

PubMed

Sung, Yao-Ting; Chen, Ju-Ling; Cha, Ji-Her; Tseng, Hou-Chiang; Chang, Tao-Hsing; Chang, Kuo-En

2015-06-01

Multilevel linguistic features have been proposed for discourse analysis, but there have been few applications of multilevel linguistic features to readability models and also few validations of such models. Most traditional readability formulae are based on generalized linear models (GLMs; e.g., discriminant analysis and multiple regression), but these models have to comply with certain statistical assumptions about data properties and include all of the data in formulae construction without pruning the outliers in advance. The use of such readability formulae tends to produce a low text classification accuracy, while using a support vector machine (SVM) in machine learning can enhance the classification outcome. The present study constructed readability models by integrating multilevel linguistic features with SVM, which is more appropriate for text classification. Taking the Chinese language as an example, this study developed 31 linguistic features as the predicting variables at the word, semantic, syntax, and cohesion levels, with grade levels of texts as the criterion variable. The study compared four types of readability models by integrating unilevel and multilevel linguistic features with GLMs and an SVM. The results indicate that adopting a multilevel approach in readability analysis provides a better representation of the complexities of both texts and the reading comprehension process.

Mesh quality control for multiply-refined tetrahedral grids

NASA Technical Reports Server (NTRS)

Biswas, Rupak; Strawn, Roger

1994-01-01

A new algorithm for controlling the quality of multiply-refined tetrahedral meshes is presented in this paper. The basic dynamic mesh adaption procedure allows localized grid refinement and coarsening to efficiently capture aerodynamic flow features in computational fluid dynamics problems; however, repeated application of the procedure may significantly deteriorate the quality of the mesh. Results presented show the effectiveness of this mesh quality algorithm and its potential in the area of helicopter aerodynamics and acoustics.

High-Fidelity Geometric Modeling and Mesh Generation for Mechanics Characterization of Polycrystalline Materials

DTIC Science & Technology

2014-10-26

From the parameterization results, we extract adaptive and anisotropic T-meshes for the further T- spline surface construction. Finally, a gradient flow...field-based method [7, 12] to generate adaptive and anisotropic quadrilateral meshes, which can be used as the control mesh for high-order T- spline ...parameterization results, we extract adaptive and anisotropic T-meshes for the further T- spline surface construction. Finally, a gradient flow-based

High-Fidelity Geometric Modeling and Mesh Generation for Mechanics Characterization of Polycrystalline Materials

DTIC Science & Technology

2015-01-07

and anisotropic quadrilateral meshes, which can be used as the control mesh for high-order T- spline surface modeling. Archival publications (published...anisotropic T-meshes for the further T- spline surface construction. Finally, a gradient flow-based method is developed to improve the T-mesh quality...shade-off. Halos are bright or dark thin regions around the boundary of the sample. These false edges around the object make many segmentation

The research on medical image classification algorithm based on PLSA-BOW model.

PubMed

Cao, C H; Cao, H L

2016-04-29

With the rapid development of modern medical imaging technology, medical image classification has become more important for medical diagnosis and treatment. To solve the existence of polysemous words and synonyms problem, this study combines the word bag model with PLSA (Probabilistic Latent Semantic Analysis) and proposes the PLSA-BOW (Probabilistic Latent Semantic Analysis-Bag of Words) model. In this paper we introduce the bag of words model in text field to image field, and build the model of visual bag of words model. The method enables the word bag model-based classification method to be further improved in accuracy. The experimental results show that the PLSA-BOW model for medical image classification can lead to a more accurate classification.

An eFTD-VP framework for efficiently generating patient-specific anatomically detailed facial soft tissue FE mesh for craniomaxillofacial surgery simulation

PubMed Central

Zhang, Xiaoyan; Kim, Daeseung; Shen, Shunyao; Yuan, Peng; Liu, Siting; Tang, Zhen; Zhang, Guangming; Zhou, Xiaobo; Gateno, Jaime

2017-01-01

Accurate surgical planning and prediction of craniomaxillofacial surgery outcome requires simulation of soft tissue changes following osteotomy. This can only be achieved by using an anatomically detailed facial soft tissue model. The current state-of-the-art of model generation is not appropriate to clinical applications due to the time-intensive nature of manual segmentation and volumetric mesh generation. The conventional patient-specific finite element (FE) mesh generation methods are to deform a template FE mesh to match the shape of a patient based on registration. However, these methods commonly produce element distortion. Additionally, the mesh density for patients depends on that of the template model. It could not be adjusted to conduct mesh density sensitivity analysis. In this study, we propose a new framework of patient-specific facial soft tissue FE mesh generation. The goal of the developed method is to efficiently generate a high-quality patient-specific hexahedral FE mesh with adjustable mesh density while preserving the accuracy in anatomical structure correspondence. Our FE mesh is generated by eFace template deformation followed by volumetric parametrization. First, the patient-specific anatomically detailed facial soft tissue model (including skin, mucosa, and muscles) is generated by deforming an eFace template model. The adaptation of the eFace template model is achieved by using a hybrid landmark-based morphing and dense surface fitting approach followed by a thin-plate spline interpolation. Then, high-quality hexahedral mesh is constructed by using volumetric parameterization. The user can control the resolution of hexahedron mesh to best reflect clinicians’ need. Our approach was validated using 30 patient models and 4 visible human datasets. The generated patient-specific FE mesh showed high surface matching accuracy, element quality, and internal structure matching accuracy. They can be directly and effectively used for clinical simulation of facial soft tissue change. PMID:29027022

An Adaptive Mesh Algorithm: Mesh Structure and Generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scannapieco, Anthony J.

2016-06-21

The purpose of Adaptive Mesh Refinement is to minimize spatial errors over the computational space not to minimize the number of computational elements. The additional result of the technique is that it may reduce the number of computational elements needed to retain a given level of spatial accuracy. Adaptive mesh refinement is a computational technique used to dynamically select, over a region of space, a set of computational elements designed to minimize spatial error in the computational model of a physical process. The fundamental idea is to increase the mesh resolution in regions where the physical variables are represented bymore » a broad spectrum of modes in k-space, hence increasing the effective global spectral coverage of those physical variables. In addition, the selection of the spatially distributed elements is done dynamically by cyclically adjusting the mesh to follow the spectral evolution of the system. Over the years three types of AMR schemes have evolved; block, patch and locally refined AMR. In block and patch AMR logical blocks of various grid sizes are overlaid to span the physical space of interest, whereas in locally refined AMR no logical blocks are employed but locally nested mesh levels are used to span the physical space. The distinction between block and patch AMR is that in block AMR the original blocks refine and coarsen entirely in time, whereas in patch AMR the patches change location and zone size with time. The type of AMR described herein is a locally refi ned AMR. In the algorithm described, at any point in physical space only one zone exists at whatever level of mesh that is appropriate for that physical location. The dynamic creation of a locally refi ned computational mesh is made practical by a judicious selection of mesh rules. With these rules the mesh is evolved via a mesh potential designed to concentrate the nest mesh in regions where the physics is modally dense, and coarsen zones in regions where the physics is modally sparse.« less

An eFTD-VP framework for efficiently generating patient-specific anatomically detailed facial soft tissue FE mesh for craniomaxillofacial surgery simulation.

PubMed

Zhang, Xiaoyan; Kim, Daeseung; Shen, Shunyao; Yuan, Peng; Liu, Siting; Tang, Zhen; Zhang, Guangming; Zhou, Xiaobo; Gateno, Jaime; Liebschner, Michael A K; Xia, James J

2018-04-01

Accurate surgical planning and prediction of craniomaxillofacial surgery outcome requires simulation of soft tissue changes following osteotomy. This can only be achieved by using an anatomically detailed facial soft tissue model. The current state-of-the-art of model generation is not appropriate to clinical applications due to the time-intensive nature of manual segmentation and volumetric mesh generation. The conventional patient-specific finite element (FE) mesh generation methods are to deform a template FE mesh to match the shape of a patient based on registration. However, these methods commonly produce element distortion. Additionally, the mesh density for patients depends on that of the template model. It could not be adjusted to conduct mesh density sensitivity analysis. In this study, we propose a new framework of patient-specific facial soft tissue FE mesh generation. The goal of the developed method is to efficiently generate a high-quality patient-specific hexahedral FE mesh with adjustable mesh density while preserving the accuracy in anatomical structure correspondence. Our FE mesh is generated by eFace template deformation followed by volumetric parametrization. First, the patient-specific anatomically detailed facial soft tissue model (including skin, mucosa, and muscles) is generated by deforming an eFace template model. The adaptation of the eFace template model is achieved by using a hybrid landmark-based morphing and dense surface fitting approach followed by a thin-plate spline interpolation. Then, high-quality hexahedral mesh is constructed by using volumetric parameterization. The user can control the resolution of hexahedron mesh to best reflect clinicians' need. Our approach was validated using 30 patient models and 4 visible human datasets. The generated patient-specific FE mesh showed high surface matching accuracy, element quality, and internal structure matching accuracy. They can be directly and effectively used for clinical simulation of facial soft tissue change.

Self-gripping mesh versus fibrin glue fixation in laparoscopic inguinal hernia repair: a randomized prospective clinical trial in young and elderly patients

PubMed Central

Bindi, Marco; Rivelli, Matteo; Solej, Mario; Enrico, Stefano; Martino, Valter

2016-01-01

Abstract Laparoscopic transabdominal preperitoneal inguinal hernia repair is a safe and effective technique. In this study we tested the hypothesis that self-gripping mesh used with the laparoscopic approach is comparable to polypropylene mesh in terms of perioperative complications, against a lower overall cost of the procedure. We carried out a prospective randomized trial comparing a group of 30 patients who underwent laparoscopic inguinal hernia repair with self-gripping mesh versus a group of 30 patients who received polypropylene mesh with fibrin glue fixation. There were no statistically significant differences between the two groups with regard to intraoperative variables, early or late intraoperative complications, chronic pain or recurrence. Self-gripping mesh in transabdominal hernia repair was found to be a valid alternative to polypropylene mesh in terms of complications, recurrence and postoperative pain. The cost analysis and comparability of outcomes support the preferential use of self-gripping mesh. PMID:28352842

Tensile behaviors of three-dimensionally free-formable titanium mesh plates for bone graft applications

NASA Astrophysics Data System (ADS)

He, Jianmei

2017-11-01

Present metal artificial bones for bone grafts have the problems like too heavy and excessive elastic modulus compared with natural bones. In this study, three-dimensionally (3D) free-formable titanium mesh plates for bone graft applications was introduced to improve these problems. Fundamental mesh shapes and patterns were designed under different base shapes and design parameters through three dimensional CAD tools from higher flexibility and strength points of view. Based on the designed mesh shape and patterns, sample specimens of titanium mesh plates with different base shapes and design variables were manufactured through laser processing. Tensile properties of the sample titanium mesh plates like volume density, tensile elastic modulus were experimentally and analytically evaluated. Experimental results showed that such titanium mesh plates had much higher flexibility and their mechanical properties could be controlled to close to the natural bones. More details on the mechanical properties of titanium mesh plates including compression, bending, torsion and durability will be carried out in future study.

[Analysis of mesh related complications after trans-vaginal mesh-augmented pelvic floor reconstruction surgery].

PubMed

Zhang, Kun; Han, Jin-song; Zhu, Fu-li; Yao, Ying

2012-09-01

To evaluate the complications after trans-vaginal mesh-augmented pelvic floor reconstruction in treatment of pelvic organ prolapse (POP). From February 2007 to October 2009, vaginal mesh procedures were performed on 91 women with POP stage III-IV in Peking University Third Hospital. The operative complications were studied. Ninety patients underwent successful surgery among 91 patients. Follow-up rate was 94% (85/90) at a median follow-up of 28.4 (15 - 44) months. One patient underwent intraoperative organ injuries, and 10 patients had postoperation mesh-related complications. The rate of mesh-related complications was 2% (2/85), 2% (2/85), 4% (3/85), 4% (3/85) on 6, 6 - 12, 12 - 24 and more than 24 months following up, respectively. Seven patients underwent conservative treatment and the symptoms were improved. Three patients underwent the second surgery, and the symptoms were cured or relieved. The incidence of mesh-related complications was low, and interventions were effective in vaginal mesh procedure.

Visual affective classification by combining visual and text features.

PubMed

Liu, Ningning; Wang, Kai; Jin, Xin; Gao, Boyang; Dellandréa, Emmanuel; Chen, Liming

2017-01-01

Affective analysis of images in social networks has drawn much attention, and the texts surrounding images are proven to provide valuable semantic meanings about image content, which can hardly be represented by low-level visual features. In this paper, we propose a novel approach for visual affective classification (VAC) task. This approach combines visual representations along with novel text features through a fusion scheme based on Dempster-Shafer (D-S) Evidence Theory. Specifically, we not only investigate different types of visual features and fusion methods for VAC, but also propose textual features to effectively capture emotional semantics from the short text associated to images based on word similarity. Experiments are conducted on three public available databases: the International Affective Picture System (IAPS), the Artistic Photos and the MirFlickr Affect set. The results demonstrate that the proposed approach combining visual and textual features provides promising results for VAC task.

Visual affective classification by combining visual and text features

PubMed Central

Liu, Ningning; Wang, Kai; Jin, Xin; Gao, Boyang; Dellandréa, Emmanuel; Chen, Liming

2017-01-01

Affective analysis of images in social networks has drawn much attention, and the texts surrounding images are proven to provide valuable semantic meanings about image content, which can hardly be represented by low-level visual features. In this paper, we propose a novel approach for visual affective classification (VAC) task. This approach combines visual representations along with novel text features through a fusion scheme based on Dempster-Shafer (D-S) Evidence Theory. Specifically, we not only investigate different types of visual features and fusion methods for VAC, but also propose textual features to effectively capture emotional semantics from the short text associated to images based on word similarity. Experiments are conducted on three public available databases: the International Affective Picture System (IAPS), the Artistic Photos and the MirFlickr Affect set. The results demonstrate that the proposed approach combining visual and textual features provides promising results for VAC task. PMID:28850566

Enhancing Vocabulary Acquisition through Reading: A Hierarchy of Text-Related Exercise Types.

ERIC Educational Resources Information Center

Wesche, M.; Paribakht, T. Sima

This paper describes a classification scheme developed to examine the effects of extensive reading on primary and second language vocabulary acquisition and reports on an experiment undertaken to test the model scheme. The classification scheme represents a hypothesized hierarchy of the degree and type of mental processing required by various…

Effects of polyglactin mesh combined with resorbable calcium carbonate or replamineform hydroxyapatite on periodontal repair in dogs.

PubMed

Moon, I S; Chai, J K; Cho, K S; Wikesjö, U M; Kim, C K

1996-10-01

This study evaluates periodontal repair and biomaterial reaction following implantation of a polyglactin mesh with or without porous resorbable calcium carbonate (RCC) or porous replamineform hydroxyapatite (RHA) in conjunction with reconstructive surgery. Ligature- and surgically-induced interproximal periodontal defects of left and right mandibular premolar teeth in 7 dogs were used. Bilaterally, mesial defects of the 2nd, 3rd and 4th premolar teeth were treated with polyglactin mesh, polyglactin mesh and RHA, or polyglactin mesh and RCC, respectively. The polyglactin mesh, shaped according to the contour of the defect, was adapted to the experimental teeth; its coronal margin positioned immediately apical to the cemento-enamel junction. Gingival flap margins were adapted and sutured to cover the polyglactin mesh completely. Clinical healing was generally uneventful. The dogs were sacrificed to provide block sections for histologic evaluation at 1, 3, 6, 12, 26, 32 and 56 weeks following wound closure. Generally, cementum regeneration was observed beginning at week 6 in all groups. Bone regeneration was observed from week 3 in polyglactin mesh-treated groups, and from week 6 in polyglactin mesh+RCC or polyglactin mesh+RHA treated groups. Bone regeneration appeared enhanced in polyglactin mesh+RCC or polyglactin mesh+RHA treated defects at week 12 and 26, with little difference between the three experimental conditions at week 56. Polyglactin mesh degradation was observed at week 3 and appeared complete at week 12. The RHA did not appear to resorb, while the RCC was gradually replaced by bone from week 3. Within limitations of the study conditions, periodontal regeneration was observed following implantation of a polyglactin mesh with or without RCC or RHA in conjunction with reconstructive surgery. As a conclusion, there seems to be no significant difference in periodontal regeneration after 12 months of healing between the group treated with the membrane only, and the group treated with the membrane and the bone substitution material. Changes in connective fiber orientation over the 1st 12 weeks of healing may suggest that "fibrous encapsulation" observed in earlier studies may only represent a transient stage in periodontal regeneration.

Superhydrophobic hierarchical structure carbon mesh films for oil/water separation application

NASA Astrophysics Data System (ADS)

Lu, Zhaoxia; Huang, Xing; Wang, Lisheng

2017-08-01

In this study, we showed that a superoleophobic mesh with the self-cleaning ability could be readily prepared by a facile spray-coating method on stainless steel mesh. Poly(methyl methacrylate) was employed to provide a stable strength between carbon nanotubes and steel mesh surface. The effect of opening size of these steel meshes on surface wetting has been investigated. The dynamics of liquid droplets was investigated as well. The as-prepared meshes exhibited both superhydrophobicity and superoleophilicity and could effectively separate water from the oil and water mixture. The present study contributes to the development of oil and water separation materials for marine industrial application.

An Interpreted Language and System for the Visualization of Unstructured Meshes

NASA Technical Reports Server (NTRS)

Moran, Patrick J.; Gerald-Yamasaki, Michael (Technical Monitor)

1998-01-01

We present an interpreted language and system supporting the visualization of unstructured meshes and the manipulation of shapes defined in terms of mesh subsets. The language features primitives inspired by geometric modeling, mathematical morphology and algebraic topology. The adaptation of the topology ideas to an interpreted environment, along with support for programming constructs such, as user function definition, provide a flexible system for analyzing a mesh and for calculating with shapes defined in terms of the mesh. We present results demonstrating some of the capabilities of the language, based on an implementation called the Shape Calculator, for tetrahedral meshes in R^3.

A structure-exploiting numbering algorithm for finite elements on extruded meshes, and its performance evaluation in Firedrake

NASA Astrophysics Data System (ADS)

Bercea, Gheorghe-Teodor; McRae, Andrew T. T.; Ham, David A.; Mitchell, Lawrence; Rathgeber, Florian; Nardi, Luigi; Luporini, Fabio; Kelly, Paul H. J.

2016-10-01

We present a generic algorithm for numbering and then efficiently iterating over the data values attached to an extruded mesh. An extruded mesh is formed by replicating an existing mesh, assumed to be unstructured, to form layers of prismatic cells. Applications of extruded meshes include, but are not limited to, the representation of three-dimensional high aspect ratio domains employed by geophysical finite element simulations. These meshes are structured in the extruded direction. The algorithm presented here exploits this structure to avoid the performance penalty traditionally associated with unstructured meshes. We evaluate the implementation of this algorithm in the Firedrake finite element system on a range of low compute intensity operations which constitute worst cases for data layout performance exploration. The experiments show that having structure along the extruded direction enables the cost of the indirect data accesses to be amortized after 10-20 layers as long as the underlying mesh is well ordered. We characterize the resulting spatial and temporal reuse in a representative set of both continuous-Galerkin and discontinuous-Galerkin discretizations. On meshes with realistic numbers of layers the performance achieved is between 70 and 90 % of a theoretical hardware-specific limit.

Computing Normal Shock-Isotropic Turbulence Interaction With Tetrahedral Meshes and the Space-Time CESE Method

NASA Astrophysics Data System (ADS)

Venkatachari, Balaji Shankar; Chang, Chau-Lyan

2016-11-01

The focus of this study is scale-resolving simulations of the canonical normal shock- isotropic turbulence interaction using unstructured tetrahedral meshes and the space-time conservation element solution element (CESE) method. Despite decades of development in unstructured mesh methods and its potential benefits of ease of mesh generation around complex geometries and mesh adaptation, direct numerical or large-eddy simulations of turbulent flows are predominantly carried out using structured hexahedral meshes. This is due to the lack of consistent multi-dimensional numerical formulations in conventional schemes for unstructured meshes that can resolve multiple physical scales and flow discontinuities simultaneously. The CESE method - due to its Riemann-solver-free shock capturing capabilities, non-dissipative baseline schemes, and flux conservation in time as well as space - has the potential to accurately simulate turbulent flows using tetrahedral meshes. As part of the study, various regimes of the shock-turbulence interaction (wrinkled and broken shock regimes) will be investigated along with a study on how adaptive refinement of tetrahedral meshes benefits this problem. The research funding for this paper has been provided by Revolutionary Computational Aerosciences (RCA) subproject under the NASA Transformative Aeronautics Concepts Program (TACP).

Histological analysis of the repair of dural lesions with silicone mesh in rats subjected to experimental lesions

PubMed Central

da Rosa, Fernando William Figueiredo; Pohl, Pedro Henrique Isoldi; Mader, Ana Maria Amaral Antônio; de Paiva, Carla Peluso; dos Santos, Aline Amaro; Bianco, Bianca; Rodrigues, Luciano Miller Reis

2015-01-01

ABSTRACT Objective To evaluate inflammatory reaction, fibrosis and neovascularization in dural repairs in Wistar rats using four techniques: simple suture, bovine collagen membrane, silicon mesh and silicon mesh with suture. Methods Thirty Wistar rats were randomized in five groups: the first was the control group, submitted to dural tear only. The others underwent durotomy and simple suture, bovine collagen membrane, silicon mesh and silicon mesh with suture. Animals were euthanized and the spine was submitted to histological evaluation with a score system (ranging from zero to 3) for inflammation, neovascularization and fibrosis. Results Fibrosis was significantly different between simple suture and silicon mesh (p=0.005) and between simple suture and mesh with suture (p=0.015), showing that fibrosis is more intense when a foreign body is used in the repair. Bovine membrane was significantly different from mesh plus suture (p=0.011) regarding vascularization. Inflammation was significantly different between simple suture and bovine collagen membrane. Conclusion Silicon mesh, compared to other commercial products available, is a possible alternative for dural repair. More studies are necessary to confirm these findings. PMID:26761555

Tangle-Free Finite Element Mesh Motion for Ablation Problems

NASA Technical Reports Server (NTRS)

Droba, Justin

2016-01-01

In numerical simulations involving boundaries that evolve in time, the primary challenge is updating the computational mesh to reflect the physical changes in the domain. In particular, the fundamental objective for any such \\mesh motion" scheme is to maintain mesh quality and suppress unphysical geometric anamolies and artifacts. External to a physical process of interest, mesh motion is an added component that determines the specifics of how to move the mesh given certain limited information from the main system. This paper develops a set of boundary conditions designed to eliminate tangling and internal collision within the context of PDE-based mesh motion (linear elasticity). These boundary conditions are developed for two- and three-dimensional meshes. The paper presents detailed algorithms for commonly occuring topological scenarios and explains how to apply them appropriately. Notably, the techniques discussed herein make use of none of the specifics of any particular formulation of mesh motion and thus are more broadly applicable. The two-dimensional algorithms are validated by an extensive verification procedure. Finally, many examples of diverse geometries in both two- and three-dimensions are shown to showcase the capabilities of the tangle-free boundary conditions.

Durable underwater superoleophobic PDDA/halloysite nanotubes decorated stainless steel mesh for efficient oil-water separation

NASA Astrophysics Data System (ADS)

Hou, Kun; Zeng, Yicheng; Zhou, Cailong; Chen, Jiahui; Wen, Xiufang; Xu, Shouping; Cheng, Jiang; Lin, Yingguang; Pi, Pihui

2017-09-01

A durable underwater superoleophobic mesh was conveniently prepared by layer-by-layer (LBL) assembly of poly (diallyldimethylammonium chloride) (PDDA) and halloysite nanotubes (HNTs) on a stainless steel mesh. The hierarchical structure and roughness of the PDDA/HNTs coating surface were controlled by adjusting the number of layer deposition cycles. When the PDDA/HNTs coating with 10 deposition cycles was decorated on the mesh with pore size of about 54 μm, the underwater superoleophobic mesh was obtained. The as-prepared underwater superoleophobic PDDA/HNTs decorated mesh exhibits outstanding oil-water separation performance with a separation efficiency of over 97% for various oil/water mixtures, which allowed water to pass through while repelled oil completely. In addition, the as-prepared decorated mesh still maintained high separation efficiency above 97% after repeated 20 separation times for hexane/water mixture or chloroform/water mixture. More importantly, the as-prepared decorated mesh is durable enough to resist chemical and mechanical challenges, such as strong alkaline, salt aqueous and sand abrasion. Therefore, the as-prepared decorated mesh has practical utility in oil-water separation due to its stable oil-water performance, remarkable chemical and mechanical durability and the facile and eco-friendly preparation process.

Mesh cruroplasty in laparoscopic repair of paraesophageal hernias is not associated with better long-term outcomes compared to primary repair.

PubMed

Tam, Vernissia; Luketich, James D; Levy, Ryan M; Christie, Neil A; Awais, Omar; Shende, Manisha; Nason, Katie S

2017-10-01

Equipoise still exists regarding routine mesh cruroplasty during laparoscopic paraesophageal hernia (PEH). We aimed to determine whether selective mesh cruroplasty is associated with differences in recurrence and patient-reported outcomes. We compared symptom outcomes (n = 688) and radiographic recurrences (n = 101; at least 10% [or 2 cm] of stomach above hiatus) for 795 non-emergent PEH repair with fundoplication (n = 106 with mesh). Heartburn, regurgitation, epigastric pain, and anti-reflux medication use decreased significantly in both groups while postoperative dysphagia (mesh; p = 0.14), and bloating (non-mesh; p = 0.32), were unchanged. Radiographic recurrence rates were similar (15 mesh [22%] versus 86 non-mesh [17%]; p = 0.32; median 27 [IQR 14, 53] months), but was associated with surgical dissatisfaction (13% vs 4%; p = 0.007). Selective mesh cruroplasty was not associated with differences in symptom outcomes or radiographic recurrence rates during laparoscopic PEH repair. Radiographic recurrence was associated with dissatisfaction, emphasizing the need for continued focus on reducing recurrences. Copyright © 2017. Published by Elsevier Inc.

50 CFR 648.84 - Gear-marking requirements and gear restrictions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... extension of a rope separator trawl must be 6-inch (15.2-cm) diamond mesh or 6.5-inch (16.5-cm) square mesh, or any combination thereof. Mesh in the bottom belly of the net must be 13-inch (33-cm) diamond mesh...

50 CFR 648.84 - Gear-marking requirements and gear restrictions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... extension of a rope separator trawl must be 6-inch (15.2-cm) diamond mesh or 6.5-inch (16.5-cm) square mesh, or any combination thereof. Mesh in the bottom belly of the net must be 13-inch (33-cm) diamond mesh...

The 3-D unstructured mesh generation using local transformations

NASA Technical Reports Server (NTRS)

Barth, Timothy J.

1993-01-01

The topics are presented in viewgraph form and include the following: 3D combinatorial edge swapping; 3D incremental triangulation via local transformations; a new approach to multigrid for unstructured meshes; surface mesh generation using local transforms; volume triangulations; viscous mesh generation; and future directions.

Financial implications of ventral hernia repair: a hospital cost analysis.

PubMed

Reynolds, Drew; Davenport, Daniel L; Korosec, Ryan L; Roth, J Scott

2013-01-01

Complicated ventral hernias are often referred to tertiary care centers. Hospital costs associated with these repairs include direct costs (mesh materials, supplies, and nonsurgeon labor costs) and indirect costs (facility fees, equipment depreciation, and unallocated labor). Operative supplies represent a significant component of direct costs, especially in an era of proprietary synthetic meshes and biologic grafts. We aim to evaluate the cost-effectiveness of complex abdominal wall hernia repair at a tertiary care referral facility. Cost data on all consecutive open ventral hernia repairs (CPT codes 49560, 49561, 49565, and 49566) performed between 1 July 2008 and 31 May 2011 were analyzed. Cases were analyzed based upon hospital status (inpatient vs. outpatient) and whether the hernia repair was a primary or secondary procedure. We examined median net revenue, direct costs, contribution margin, indirect costs, and net profit/loss. Among primary hernia repairs, cost data were further analyzed based upon mesh utilization (no mesh, synthetic, or biologic). Four-hundred and fifteen patients underwent ventral hernia repair (353 inpatients and 62 outpatients); 173 inpatients underwent ventral hernia repair as the primary procedure; 180 inpatients underwent hernia repair as a secondary procedure. Median net revenue ($17,310 vs. 10,360, p < 0.001) and net losses (3,430 vs. 1,700, p < 0.025) were significantly greater for those who underwent hernia repair as a secondary procedure. Among inpatients undergoing ventral hernia repair as the primary procedure, 46 were repaired without mesh; 79 were repaired with synthetic mesh and 48 with biologic mesh. Median direct costs for cases performed without mesh were $5,432; median direct costs for those using synthetic and biologic mesh were $7,590 and 16,970, respectively (p < .01). Median net losses for repairs without mesh were $500. Median net profit of $60 was observed for synthetic mesh-based repairs. The median contribution margin for cases utilizing biologic mesh was -$4,560, and the median net financial loss was $8,370. Outpatient ventral hernia repairs, with and without synthetic mesh, resulted in median net losses of $1,560 and 230, respectively. Ventral hernia repair is associated with overall financial losses. Inpatient synthetic mesh repairs are essentially budget neutral. Outpatient and inpatient repairs without mesh result in net financial losses. Inpatient biologic mesh repairs result in a negative contribution margin and striking net financial losses. Cost-effective strategies for managing ventral hernias in a tertiary care environment need to be developed in light of the financial implications of this patient population.

Ultimate Strength of Ferro-Geopolymer Composite Built-Up I Joist

NASA Astrophysics Data System (ADS)

Vipin, K. T.; Ganesan, N.; Indira, P. V.

2017-07-01

An experimental study was carried out to study the behaviour of ferro-geopolymer built-up I- joist with different types of mesh reinforcements under flexure. Mesh reinforcements considered in this study are square welded meshes, square woven meshes and hexagonal meshes. First crack load as well as ultimate strength of ferro-geopolymer built-up I-joist in flexure was obtained. An attempt was made to predict the first crack load and ultimate moment capacity of the specimen.

Mesh abdominal wall hernia surgery is safe and effective-the harm New Zealand media has done.

PubMed

Kelly, Steven

2017-10-06

Patients in New Zealand have now developed a fear of mesh abdominal wall hernia repair due to inaccurate media reporting. This article outlines the extensive literature that confirms abdominal wall mesh hernia repair is safe and effective. The worsening confidence in the transvaginal mesh prolapse repair should not adversely affect the good results of mesh abdominal wall hernia repair. New Zealand general surgeons are well trained in providing modern hernia surgery.

Flight Behaviors of a Complex Projectile Using a Coupled Computational Fluid Dynamics (CFD)-based Simulation Technique: Free Motion

DTIC Science & Technology

2015-09-01

million cells each. These 4 canard meshes were then overset with the 10 background projectile body mesh using the Chimera procedure.29 The final... Chimera -overlapped mesh for each of the 2 (fin cant) models consists of approximately 43 million cells. A circumferential cross section (Fig. 4... Chimera procedure requires proper transfer of information between the background mesh and the canard meshes at every time step. However, the advantage

Root-cause analysis of the better performance of the coarse-mesh finite-difference method for CANDU-type reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, W.

2012-07-01

Recent assessment results indicate that the coarse-mesh finite-difference method (FDM) gives consistently smaller percent differences in channel powers than the fine-mesh FDM when compared to the reference MCNP solution for CANDU-type reactors. However, there is an impression that the fine-mesh FDM should always give more accurate results than the coarse-mesh FDM in theory. To answer the question if the better performance of the coarse-mesh FDM for CANDU-type reactors was just a coincidence (cancellation of errors) or caused by the use of heavy water or the use of lattice-homogenized cross sections for the cluster fuel geometry in the diffusion calculation, threemore » benchmark problems were set up with three different fuel lattices: CANDU, HWR and PWR. These benchmark problems were then used to analyze the root cause of the better performance of the coarse-mesh FDM for CANDU-type reactors. The analyses confirm that the better performance of the coarse-mesh FDM for CANDU-type reactors is mainly caused by the use of lattice-homogenized cross sections for the sub-meshes of the cluster fuel geometry in the diffusion calculation. Based on the analyses, it is recommended to use 2 x 2 coarse-mesh FDM to analyze CANDU-type reactors when lattice-homogenized cross sections are used in the core analysis. (authors)« less

Preventing Mesh Pore Collapse by Designing Mesh Pores With Auxetic Geometries: A Comprehensive Evaluation Via Computational Modeling.

PubMed

Knight, Katrina M; Moalli, Pamela A; Abramowitch, Steven D

2018-05-01

Pelvic organ prolapse (POP) meshes are exposed to predominately tensile loading conditions in vivo that can lead to pore collapse by 70-90%, decreasing overall porosity and providing a plausible mechanism for the contraction/shrinkage of mesh observed following implantation. To prevent pore collapse, we proposed to design synthetic meshes with a macrostructure that results in auxetic behavior, the pores expand laterally, instead of contracting when loaded. Such behavior can be achieved with a range of auxetic structures/geometries. This study utilized finite element analysis (FEA) to assess the behavior of mesh models with eight auxetic pore geometries subjected to uniaxial loading to evaluate their potential to allow for pore expansion while simultaneously providing resistance to tensile loading. Overall, substituting auxetic geometries for standard pore geometries yielded more pore expansion, but often at the expense of increased model elongation, with two of the eight auxetics not able to maintain pore expansion at higher levels of tension. Meshes with stable pore geometries that remain open with loading will afford the ingrowth of host tissue into the pores and improved integration of the mesh. Given the demonstrated ability of auxetic geometries to allow for pore size maintenance (and pore expansion), auxetically designed meshes have the potential to significantly impact surgical outcomes and decrease the likelihood of major mesh-related complications.

Array-based, parallel hierarchical mesh refinement algorithms for unstructured meshes

DOE PAGES

Ray, Navamita; Grindeanu, Iulian; Zhao, Xinglin; ...

2016-08-18

In this paper, we describe an array-based hierarchical mesh refinement capability through uniform refinement of unstructured meshes for efficient solution of PDE's using finite element methods and multigrid solvers. A multi-degree, multi-dimensional and multi-level framework is designed to generate the nested hierarchies from an initial coarse mesh that can be used for a variety of purposes such as in multigrid solvers/preconditioners, to do solution convergence and verification studies and to improve overall parallel efficiency by decreasing I/O bandwidth requirements (by loading smaller meshes and in memory refinement). We also describe a high-order boundary reconstruction capability that can be used tomore » project the new points after refinement using high-order approximations instead of linear projection in order to minimize and provide more control on geometrical errors introduced by curved boundaries.The capability is developed under the parallel unstructured mesh framework "Mesh Oriented dAtaBase" (MOAB Tautges et al. (2004)). We describe the underlying data structures and algorithms to generate such hierarchies in parallel and present numerical results for computational efficiency and effect on mesh quality. Furthermore, we also present results to demonstrate the applicability of the developed capability to study convergence properties of different point projection schemes for various mesh hierarchies and to a multigrid finite-element solver for elliptic problems.« less

Effects of Titanium Mesh Surfaces-Coated with Hydroxyapatite/β-Tricalcium Phosphate Nanotubes on Acetabular Bone Defects in Rabbits

PubMed Central

Nguyen, Thuy-Duong Thi; Bae, Tae-Sung; Yang, Dae-hyeok; Park, Myung-sik; Yoon, Sun-jung

2017-01-01

The management of severe acetabular bone defects in revision reconstructive orthopedic surgery is challenging. In this study, cyclic precalcification (CP) treatment was used on both nanotube-surface Ti-mesh and a bone graft substitute for the acetabular defect model, and its effects were assessed in vitro and in vivo. Nanotube-Ti mesh coated with hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) was manufactured by an anodizing and a sintering method, respectively. An 8 mm diameter defect was created on each acetabulum of eight rabbits, then treated by grafting materials and covered by Ti meshes. At four and eight weeks, postoperatively, biopsies were performed for histomorphometric analyses. The newly-formed bone layers under cyclic precalcified anodized Ti (CP-AT) meshes were superior with regard to the mineralized area at both four and eight weeks, as compared with that under untreated Ti meshes. Active bone regeneration at 2–4 weeks was stronger than at 6–8 weeks, particularly with treated biphasic ceramic (p < 0.05). CP improved the bioactivity of Ti meshes and biphasic grafting materials. Moreover, the precalcified nanotubular Ti meshes could enhance early contact bone formation on the mesh and, therefore, may reduce the collapse of Ti meshes into the defect, increasing the sufficiency of acetabular reconstruction. Finally, cyclic precalcification did not affect bone regeneration by biphasic grafting materials in vivo. PMID:28686210

Large-scale subject-specific cerebral arterial tree modeling using automated parametric mesh generation for blood flow simulation.

PubMed

Ghaffari, Mahsa; Tangen, Kevin; Alaraj, Ali; Du, Xinjian; Charbel, Fady T; Linninger, Andreas A

2017-12-01

In this paper, we present a novel technique for automatic parametric mesh generation of subject-specific cerebral arterial trees. This technique generates high-quality and anatomically accurate computational meshes for fast blood flow simulations extending the scope of 3D vascular modeling to a large portion of cerebral arterial trees. For this purpose, a parametric meshing procedure was developed to automatically decompose the vascular skeleton, extract geometric features and generate hexahedral meshes using a body-fitted coordinate system that optimally follows the vascular network topology. To validate the anatomical accuracy of the reconstructed vasculature, we performed statistical analysis to quantify the alignment between parametric meshes and raw vascular images using receiver operating characteristic curve. Geometric accuracy evaluation showed an agreement with area under the curves value of 0.87 between the constructed mesh and raw MRA data sets. Parametric meshing yielded on-average, 36.6% and 21.7% orthogonal and equiangular skew quality improvement over the unstructured tetrahedral meshes. The parametric meshing and processing pipeline constitutes an automated technique to reconstruct and simulate blood flow throughout a large portion of the cerebral arterial tree down to the level of pial vessels. This study is the first step towards fast large-scale subject-specific hemodynamic analysis for clinical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Unstructured mesh adaptivity for urban flooding modelling

NASA Astrophysics Data System (ADS)

Hu, R.; Fang, F.; Salinas, P.; Pain, C. C.

2018-05-01

Over the past few decades, urban floods have been gaining more attention due to their increase in frequency. To provide reliable flooding predictions in urban areas, various numerical models have been developed to perform high-resolution flood simulations. However, the use of high-resolution meshes across the whole computational domain causes a high computational burden. In this paper, a 2D control-volume and finite-element flood model using adaptive unstructured mesh technology has been developed. This adaptive unstructured mesh technique enables meshes to be adapted optimally in time and space in response to the evolving flow features, thus providing sufficient mesh resolution where and when it is required. It has the advantage of capturing the details of local flows and wetting and drying front while reducing the computational cost. Complex topographic features are represented accurately during the flooding process. For example, the high-resolution meshes around the buildings and steep regions are placed when the flooding water reaches these regions. In this work a flooding event that happened in 2002 in Glasgow, Scotland, United Kingdom has been simulated to demonstrate the capability of the adaptive unstructured mesh flooding model. The simulations have been performed using both fixed and adaptive unstructured meshes, and then results have been compared with those published 2D and 3D results. The presented method shows that the 2D adaptive mesh model provides accurate results while having a low computational cost.

Staggered Mesh Ewald: An extension of the Smooth Particle-Mesh Ewald method adding great versatility

PubMed Central

Cerutti, David S.; Duke, Robert E.; Darden, Thomas A.; Lybrand, Terry P.

2009-01-01

We draw on an old technique for improving the accuracy of mesh-based field calculations to extend the popular Smooth Particle Mesh Ewald (SPME) algorithm as the Staggered Mesh Ewald (StME) algorithm. StME improves the accuracy of computed forces by up to 1.2 orders of magnitude and also reduces the drift in system momentum inherent in the SPME method by averaging the results of two separate reciprocal space calculations. StME can use charge mesh spacings roughly 1.5× larger than SPME to obtain comparable levels of accuracy; the one mesh in an SPME calculation can therefore be replaced with two separate meshes, each less than one third of the original size. Coarsening the charge mesh can be balanced with reductions in the direct space cutoff to optimize performance: the efficiency of StME rivals or exceeds that of SPME calculations with similarly optimized parameters. StME may also offer advantages for parallel molecular dynamics simulations because it permits the use of coarser meshes without requiring higher orders of charge interpolation and also because the two reciprocal space calculations can be run independently if that is most suitable for the machine architecture. We are planning other improvements to the standard SPME algorithm, and anticipate that StME will work synergistically will all of them to dramatically improve the efficiency and parallel scaling of molecular simulations. PMID:20174456

A voxel-based finite element model for the prediction of bladder deformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chai Xiangfei; Herk, Marcel van; Hulshof, Maarten C. C. M.

2012-01-15

Purpose: A finite element (FE) bladder model was previously developed to predict bladder deformation caused by bladder filling change. However, two factors prevent a wide application of FE models: (1) the labor required to construct a FE model with high quality mesh and (2) long computation time needed to construct the FE model and solve the FE equations. In this work, we address these issues by constructing a low-resolution voxel-based FE bladder model directly from the binary segmentation images and compare the accuracy and computational efficiency of the voxel-based model used to simulate bladder deformation with those of a classicalmore » FE model with a tetrahedral mesh. Methods: For ten healthy volunteers, a series of MRI scans of the pelvic region was recorded at regular intervals of 10 min over 1 h. For this series of scans, the bladder volume gradually increased while rectal volume remained constant. All pelvic structures were defined from a reference image for each volunteer, including bladder wall, small bowel, prostate (male), uterus (female), rectum, pelvic bone, spine, and the rest of the body. Four separate FE models were constructed from these structures: one with a tetrahedral mesh (used in previous study), one with a uniform hexahedral mesh, one with a nonuniform hexahedral mesh, and one with a low-resolution nonuniform hexahedral mesh. Appropriate material properties were assigned to all structures and uniform pressure was applied to the inner bladder wall to simulate bladder deformation from urine inflow. Performance of the hexahedral meshes was evaluated against the performance of the standard tetrahedral mesh by comparing the accuracy of bladder shape prediction and computational efficiency. Results: FE model with a hexahedral mesh can be quickly and automatically constructed. No substantial differences were observed between the simulation results of the tetrahedral mesh and hexahedral meshes (<1% difference in mean dice similarity coefficient to manual contours and <0.02 cm difference in mean standard deviation of residual errors). The average equation solving time (without manual intervention) for the first two types of hexahedral meshes increased to 2.3 h and 2.6 h compared to the 1.1 h needed for the tetrahedral mesh, however, the low-resolution nonuniform hexahedral mesh dramatically decreased the equation solving time to 3 min without reducing accuracy. Conclusions: Voxel-based mesh generation allows fast, automatic, and robust creation of finite element bladder models directly from binary segmentation images without user intervention. Even the low-resolution voxel-based hexahedral mesh yields comparable accuracy in bladder shape prediction and more than 20 times faster in computational speed compared to the tetrahedral mesh. This approach makes it more feasible and accessible to apply FE method to model bladder deformation in adaptive radiotherapy.« less

Unstructured and adaptive mesh generation for high Reynolds number viscous flows

NASA Technical Reports Server (NTRS)

Mavriplis, Dimitri J.

1991-01-01

A method for generating and adaptively refining a highly stretched unstructured mesh suitable for the computation of high-Reynolds-number viscous flows about arbitrary two-dimensional geometries was developed. The method is based on the Delaunay triangulation of a predetermined set of points and employs a local mapping in order to achieve the high stretching rates required in the boundary-layer and wake regions. The initial mesh-point distribution is determined in a geometry-adaptive manner which clusters points in regions of high curvature and sharp corners. Adaptive mesh refinement is achieved by adding new points in regions of large flow gradients, and locally retriangulating; thus, obviating the need for global mesh regeneration. Initial and adapted meshes about complex multi-element airfoil geometries are shown and compressible flow solutions are computed on these meshes.

The P-Mesh: A Commodity-based Scalable Network Architecture for Clusters

NASA Technical Reports Server (NTRS)

Nitzberg, Bill; Kuszmaul, Chris; Stockdale, Ian; Becker, Jeff; Jiang, John; Wong, Parkson; Tweten, David (Technical Monitor)

1998-01-01

We designed a new network architecture, the P-Mesh which combines the scalability and fault resilience of a torus with the performance of a switch. We compare the scalability, performance, and cost of the hub, switch, torus, tree, and P-Mesh architectures. The latter three are capable of scaling to thousands of nodes, however, the torus has severe performance limitations with that many processors. The tree and P-Mesh have similar latency, bandwidth, and bisection bandwidth, but the P-Mesh outperforms the switch architecture (a lower bound for tree performance) on 16-node NAB Parallel Benchmark tests by up to 23%, and costs 40% less. Further, the P-Mesh has better fault resilience characteristics. The P-Mesh architecture trades increased management overhead for lower cost, and is a good bridging technology while the price of tree uplinks is expensive.

Bluetooth Low Energy Mesh Networks: A Survey

PubMed Central

Darroudi, Seyed Mahdi; Gomez, Carles

2017-01-01

Bluetooth Low Energy (BLE) has gained significant momentum. However, the original design of BLE focused on star topology networking, which limits network coverage range and precludes end-to-end path diversity. In contrast, other competing technologies overcome such constraints by supporting the mesh network topology. For these reasons, academia, industry, and standards development organizations have been designing solutions to enable BLE mesh networks. Nevertheless, the literature lacks a consolidated view on this emerging area. This paper comprehensively surveys state of the art BLE mesh networking. We first provide a taxonomy of BLE mesh network solutions. We then review the solutions, describing the variety of approaches that leverage existing BLE functionality to enable BLE mesh networks. We identify crucial aspects of BLE mesh network solutions and discuss their advantages and drawbacks. Finally, we highlight currently open issues. PMID:28640183

Histologic and biomechanical evaluation of a novel macroporous polytetrafluoroethylene knit mesh compared to lightweight and heavyweight polypropylene mesh in a porcine model of ventral incisional hernia repair

PubMed Central

Melman, L.; Jenkins, E. D.; Hamilton, N. A.; Bender, L. C.; Brodt, M. D.; Deeken, C. R.; Greco, S. C.; Frisella, M. M.

2013-01-01

Purpose To evaluate the biocompatibility of heavyweight polypropylene (HWPP), lightweight polypropylene (LWPP), and monofilament knit polytetrafluoroethylene (mkPTFE) mesh by comparing biomechanics and histologic response at 1, 3, and 5 months in a porcine model of incisional hernia repair. Methods Bilateral full-thickness abdominal wall defects measuring 4 cm in length were created in 27 Yucatan minipigs. Twenty-one days after hernia creation, animals underwent bilateral preperitoneal ventral hernia repair with 8 × 10 cm pieces of mesh. Repairs were randomized to Bard®Mesh (HWPP, Bard/Davol, http://www.davol.com), ULTRAPRO® (LWPP, Ethicon, http://www.ethicon.com), and GORE®INFINIT Mesh (mkPTFE, Gore & Associates, http://www.gore.com). Nine animals were sacrificed at each timepoint (1, 3, and 5 months). At harvest, a 3 × 4 cm sample of mesh and incorporated tissue was taken from the center of the implant site and subjected to uniaxial tensile testing at a rate of 0.42 mm/s. The maximum force (N) and tensile strength (N/cm) were measured with a tensiometer, and stiffness (N/mm) was calculated from the slope of the force-versus-displacement curve. Adjacent sections of tissue were stained with hematoxylin and eosin (H&E) and analyzed for inflammation, fibrosis, and tissue ingrowth. Data are reported as mean ± SEM. Statistical significance (P < 0.05) was determined using a two-way ANOVA and Bonferroni post-test. Results No significant difference in maximum force was detected between meshes at any of the time points (P > 0.05 for all comparisons). However, for each mesh type, the maximum strength at 5 months was significantly lower than that at 1 month (P < 0.05). No significant difference in stiffness was detected between the mesh types or between timepoints (P > 0.05 for all comparisons). No significant differences with regard to inflammation, fibrosis, or tissue ingrowth were detected between mesh types at any time point (P > 0.09 for all comparisons). However, over time, inflammation decreased significantly for all mesh types (P < 0.001) and tissue ingrowth reached a slight peak between 1 and 3 months (P = 0.001) but did not significantly change thereafter (P > 0.09). Conclusions The maximum tensile strength of mesh in the abdominal wall decreased over time for HWPP, LWPP, and mkPTFE mesh materials alike. This trend may actually reflect inability to adequately grip specimens at later time points rather than any mesh-specific trend. Histologically, inflammation decreased with time (P = 0.000), and tissue ingrowth increased (P = 0.019) for all meshes. No specific trends were observed between the polypropylene meshes and the monofilament knit PTFE, suggesting that this novel construction may be a suitable alternative to existing polypropylene meshes. PMID:21279663

Histologic and biomechanical evaluation of a novel macroporous polytetrafluoroethylene knit mesh compared to lightweight and heavyweight polypropylene mesh in a porcine model of ventral incisional hernia repair.

PubMed

Melman, L; Jenkins, E D; Hamilton, N A; Bender, L C; Brodt, M D; Deeken, C R; Greco, S C; Frisella, M M; Matthews, B D

2011-08-01

To evaluate the biocompatibility of heavyweight polypropylene (HWPP), lightweight polypropylene (LWPP), and monofilament knit polytetrafluoroethylene (mkPTFE) mesh by comparing biomechanics and histologic response at 1, 3, and 5 months in a porcine model of incisional hernia repair. Bilateral full-thickness abdominal wall defects measuring 4 cm in length were created in 27 Yucatan minipigs. Twenty-one days after hernia creation, animals underwent bilateral preperitoneal ventral hernia repair with 8 × 10 cm pieces of mesh. Repairs were randomized to Bard(®)Mesh (HWPP, Bard/Davol, http://www.davol.com), ULTRAPRO(®) (LWPP, Ethicon, http://www.ethicon.com), and GORE(®)INFINIT Mesh (mkPTFE, Gore & Associates, http://www.gore.com). Nine animals were sacrificed at each timepoint (1, 3, and 5 months). At harvest, a 3 × 4 cm sample of mesh and incorporated tissue was taken from the center of the implant site and subjected to uniaxial tensile testing at a rate of 0.42 mm/s. The maximum force (N) and tensile strength (N/cm) were measured with a tensiometer, and stiffness (N/mm) was calculated from the slope of the force-versus-displacement curve. Adjacent sections of tissue were stained with hematoxylin and eosin (H&E) and analyzed for inflammation, fibrosis, and tissue ingrowth. Data are reported as mean ± SEM. Statistical significance (P < 0.05) was determined using a two-way ANOVA and Bonferroni post-test. No significant difference in maximum force was detected between meshes at any of the time points (P > 0.05 for all comparisons). However, for each mesh type, the maximum strength at 5 months was significantly lower than that at 1 month (P < 0.05). No significant difference in stiffness was detected between the mesh types or between timepoints (P > 0.05 for all comparisons). No significant differences with regard to inflammation, fibrosis, or tissue ingrowth were detected between mesh types at any time point (P > 0.09 for all comparisons). However, over time, inflammation decreased significantly for all mesh types (P < 0.001) and tissue ingrowth reached a slight peak between 1 and 3 months (P = 0.001) but did not significantly change thereafter (P > 0.09). The maximum tensile strength of mesh in the abdominal wall decreased over time for HWPP, LWPP, and mkPTFE mesh materials alike. This trend may actually reflect inability to adequately grip specimens at later time points rather than any mesh-specific trend. Histologically, inflammation decreased with time (P = 0.000), and tissue ingrowth increased (P = 0.019) for all meshes. No specific trends were observed between the polypropylene meshes and the monofilament knit PTFE, suggesting that this novel construction may be a suitable alternative to existing polypropylene meshes.

Mesh Displacement After Bilateral Inguinal Hernia Repair With No Fixation

PubMed Central

Rocha, Gabriela Moreira; Campos, Antonio Carlos Ligocki; Paulin, João Augusto Nocera; Coelho, Julio Cesar Uili

2017-01-01

Background and Objectives: About 20% of patients with inguinal hernia present bilateral hernias in the diagnosis. In these cases, laparoscopic procedure is considered gold standard approach. Mesh fixation is considered important step toward avoiding recurrence. However, because of cost and risk of pain, real need for mesh fixation has been debated. For bilateral inguinal hernias, there are few specific data about non fixation and mesh displacement. We assessed mesh movement in patients who had undergone laparoscopic bilateral inguinal hernia repair without mesh fixation and compared the results with those obtained in patients with unilateral hernia. Methods: From January 2012 through May 2014, 20 consecutive patients with bilateral inguinal hernia underwent TEP repair with no mesh fixation. Results were compared with 50 consecutive patients with unilateral inguinal hernia surgically repaired with similar technique. Mesh was marked with 3 clips. Mesh movements were measured by comparing initial radiography performed at the end of surgery, with a second radiographic scan performed 30 days later. Results: Mean movements of all 3 clips in bilateral nonfixation (NF) group were 0.15–0.4 cm compared with 0.1–0.3 cm in unilateral NF group. Overall displacement of bilateral and unilateral NF groups did not show significant difference. Mean overall displacement was 1.9 cm versus 1.8 cm in the bilateral and unilateral NF groups, respectively (P = .78). Conclusions: TEP with no mesh fixation is safe in bilateral inguinal repairs. Early mesh displacement is minimal. This technique can be safely used in most patients with inguinal hernia. PMID:28904521

A critical review of biologic mesh use in ventral hernia repairs under contaminated conditions.

PubMed

Primus, F E; Harris, H W

2013-02-01

We used an evidence-based approach to determine whether the promotions and claims of superiority of biologic mesh over synthetic mesh use in ventral hernia repairs (VHRs) under contaminated conditions were sound and valid. We searched the Medline database to specifically identify review articles relating to biologic mesh and VHR and critically reviewed these studies using an evidence-based approach. For the past 45 years, four clinical reviews and one systematic review have included biologic meshes as part of a larger discussion on available prosthetics for VHR. All reviews supported biologic mesh use, especially in the setting of contaminated fields. Yet, the primary literature included in these reviews and served as the basis for these conclusions consisted entirely of case series and case reports, which have the lowest level of evidence in determining scientific validity. Furthermore, the FDA has neither cleared nor approved this particular use. The cumulative data regarding biologic mesh use in VHRs under contaminated conditions does not support the claim that it is better than synthetic mesh used under the same conditions. The highly promoted and at least moderately utilized practice of placing biologic mesh in contamination is being done outside of the original intended use, and a re-evaluation of or possible moratorium on biologic mesh use in hernia surgery is seriously warranted. Alternatively, an industry-sponsored national registry of patients in whom ventral hernia repairs involved biologic mesh would substantively add to our understanding regarding how these intriguing biomaterials are being used and their overall clinical efficacy.

Transabdominal preperitoneal herniorrhaphy using laser-assisted tissue soldering in a porcine model.

PubMed

Lanzafame, Raymond J; Soltz, Barbara A; Stadler, Istvan; Soltz, Robert

2009-01-01

Collagen solder is capable of fixation of surgical meshes during laparoscopic herniorrhaphy without compromising tissue integration, increasing adhesions or inflammation. This pilot study describes development of instrumentation and techniques for transabdominal preperitoneal (TAPP) herniorrhaphy using laser-assisted soldering technology. Anesthetized 20-kg to 25-kg female Yorkshire pigs underwent laparoscopy performed using a 3-trocar technique. Peritoneal incisions were made and pockets created in the preperitoneal space for mesh placement. Parietex TEC mesh segments embedded in 60% collagen-solder were soldered to the muscle surface by using a prototype laser (1.45micro, 4.5W CW, 5mm spot, and 55 degrees C set temperature) and custom laparoscopic handpiece. Parietex TEC mesh segments (Control) were affixed to the muscle with fibrin sealant (Tisseel). Peritoneal closure was with staples (Control) or by soldering collagen embedded Vicryl mesh segments over the peritoneal incision (Mesh/TAPP). Segments were inserted using a specially designed introducer. Animals were recovered and underwent second-look laparoscopy at 6 weeks postimplantation. Mesh sites were harvested after animals were euthanized. The mesh-solder constructs were easily inserted and affixed in the TAPP approach. Tisseel tended to drip during application, particularly in vertical and ventral locations. Postoperative healing was similar to Control segments in all cases. Mesh/TAPP closures healed without scarring or adhesion formation. Collagen-based tissue soldering permits normal wound healing and may mitigate or reduce use of staples for laparoscopic mesh fixation and peritoneal closure. Laser-assisted mesh fixation and peritoneal closure is a promising alternative for laparoscopic herniorrhaphy. Further development of this strategy is warranted.

50 CFR 648.23 - Mackerel, squid, and butterfish gear restrictions.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) diamond mesh, inside stretch measure, applied throughout the codend for at least 100 continuous meshes..., inside stretch measure, applied throughout the codend for at least 150 continuous meshes forward of the... inches (48 mm) during Trimester II (May-Aug), diamond mesh, inside stretch measure. “Top of the regulated...

50 CFR 648.23 - Mackerel, squid, and butterfish gear restrictions.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) diamond mesh, inside stretch measure, applied throughout the codend for at least 100 continuous meshes..., inside stretch measure, applied throughout the codend for at least 150 continuous meshes forward of the... inches (48 mm) during Trimester II (May-Aug), diamond mesh, inside stretch measure. “Top of the regulated...

50 CFR 648.23 - Gear restrictions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... mesh, inside stretch measure, applied throughout the codend for at least 100 continuous meshes forward... (Sept-Dec), or 17/8 inches (48 mm), during Trimester II (May-Aug), diamond mesh, inside stretch measure...), during Trimester II (May-Aug), diamond mesh, inside stretch measure. “Top of the regulated portion of the...

50 CFR 648.23 - Mackerel, squid, and butterfish gear restrictions.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) diamond mesh, inside stretch measure, applied throughout the codend for at least 100 continuous meshes..., inside stretch measure, applied throughout the codend for at least 150 continuous meshes forward of the... inches (48 mm) during Trimester II (May-Aug), diamond mesh, inside stretch measure. “Top of the regulated...

21 CFR 870.3650 - Pacemaker polymeric mesh bag.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

21 CFR 870.3650 - Pacemaker polymeric mesh bag.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

21 CFR 870.3650 - Pacemaker polymeric mesh bag.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

21 CFR 870.3650 - Pacemaker polymeric mesh bag.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Pacemaker polymeric mesh bag. 870.3650 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3650 Pacemaker polymeric mesh bag. (a) Identification. A pacemaker polymeric mesh bag is an implanted device used to hold a...

Identifying Wrist Fracture Patients with High Accuracy by Automatic Categorization of X-ray Reports

PubMed Central

de Bruijn, Berry; Cranney, Ann; O’Donnell, Siobhan; Martin, Joel D.; Forster, Alan J.

2006-01-01

The authors performed this study to determine the accuracy of several text classification methods to categorize wrist x-ray reports. We randomly sampled 751 textual wrist x-ray reports. Two expert reviewers rated the presence (n = 301) or absence (n = 450) of an acute fracture of wrist. We developed two information retrieval (IR) text classification methods and a machine learning method using a support vector machine (TC-1). In cross-validation on the derivation set (n = 493), TC-1 outperformed the two IR based methods and six benchmark classifiers, including Naive Bayes and a Neural Network. In the validation set (n = 258), TC-1 demonstrated consistent performance with 93.8% accuracy; 95.5% sensitivity; 92.9% specificity; and 87.5% positive predictive value. TC-1 was easy to implement and superior in performance to the other classification methods. PMID:16929046

Pelvic Organ Prolapse---Vaginal and Laparoscopic Mesh: The Evidence.

PubMed

Richter, Lee A; Sokol, Andrew I

2016-03-01

This report summarizes the current literature on abdominal, laparoscopic, and transvaginal mesh for the treatment of pelvic organ prolapse. This article reviews objective and subjective cure rates as well as complications associated with synthetic mesh use for pelvic organ prolapse repair. The focus is on the latest literature that provides evidence for when synthetic mesh use is most appropriate. The use of mesh for the repair of urinary incontinence is not reviewed in this article. Copyright © 2016 Elsevier Inc. All rights reserved.

Hexahedral finite element mesh coarsening using pillowing technique

DOEpatents

Staten, Matthew L [Pittsburgh, PA; Woodbury, Adam C [Provo, UT; Benzley, Steven E [Provo, UT; Shepherd, Jason F [Edgewood, NM

2012-06-05

A techniques for coarsening a hexahedral mesh is described. The technique includes identifying a coarsening region within a hexahedral mesh to be coarsened. A boundary sheet of hexahedral elements is inserted into the hexahedral mesh around the coarsening region. A column of hexahedral elements is identified within the boundary sheet. The column of hexahedral elements is collapsed to create an extraction sheet of hexahedral elements contained within the coarsening region. Then, the extraction sheet of hexahedral elements is extracted to coarsen the hexahedral mesh.

Meshing of a Spiral Bevel Gearset with 3D Finite Element Analysis

NASA Technical Reports Server (NTRS)

Bibel, George D.; Handschuh, Robert

1996-01-01

Recent advances in spiral bevel gear geometry and finite element technology make it practical to conduct a structural analysis and analytically roll the gearset through mesh. With the advent of user specific programming linked to 3D solid modelers and mesh generators, model generation has become greatly automated. Contact algorithms available in general purpose finite element codes eliminate the need for the use and alignment of gap elements. Once the gearset is placed in mesh, user subroutines attached to the FE code easily roll the gearset through mesh. The method is described in detail. Preliminary results for a gearset segment showing the progression of the contact lineload is given as the gears roll through mesh.

Committee Opinion no. 513: vaginal placement of synthetic mesh for pelvic organ prolapse.

PubMed

2011-12-01

Since 2004, use of synthetic mesh has increased in vaginal surgery for the treatment of pelvic organ prolapse. However, concerns exist about the safety and efficacy of transvaginally placed mesh. Based on the currently available limited data, although many patients undergoing mesh-augmented vaginal repairs heal well without problems, there seems to be a small but significant group of patients who experience permanent and life-altering sequelae, including pain and dyspareunia, from the use of vaginal mesh. The American College of Obstetricians and Gynecologists and the American Urogynecologic Society provide background information on the use of vaginally placed mesh for the treatment of pelvic organ prolapse and offer recommendations for practice.

Vaginal placement of synthetic mesh for pelvic organ prolapse.

PubMed

2012-01-01

Since 2004, use of synthetic mesh has increased in vaginal surgery for the treatment of pelvic organ prolapse. However, concerns exist about the safety and efficacy of transvaginally placed mesh. Based on the currently available limited data, although many patients undergoing mesh-augmented vaginal repairs heal well without problems, there seems to be a small but significant group of patients who experience permanent and life-altering sequelae, including pain and dyspareunia, from the use of vaginal mesh. The American College of Obstetricians and Gynecologists and the American Urogynecologic Society provide background information on the use of vaginally placed mesh for the treatment of pelvic organ prolapse and offer recommendations for practice.

Applying Active Learning to Assertion Classification of Concepts in Clinical Text

PubMed Central

Chen, Yukun; Mani, Subramani; Xu, Hua

2012-01-01

Supervised machine learning methods for clinical natural language processing (NLP) research require a large number of annotated samples, which are very expensive to build because of the involvement of physicians. Active learning, an approach that actively samples from a large pool, provides an alternative solution. Its major goal in classification is to reduce the annotation effort while maintaining the quality of the predictive model. However, few studies have investigated its uses in clinical NLP. This paper reports an application of active learning to a clinical text classification task: to determine the assertion status of clinical concepts. The annotated corpus for the assertion classification task in the 2010 i2b2/VA Clinical NLP Challenge was used in this study. We implemented several existing and newly developed active learning algorithms and assessed their uses. The outcome is reported in the global ALC score, based on the Area under the average Learning Curve of the AUC (Area Under the Curve) score. Results showed that when the same number of annotated samples was used, active learning strategies could generate better classification models (best ALC – 0.7715) than the passive learning method (random sampling) (ALC – 0.7411). Moreover, to achieve the same classification performance, active learning strategies required fewer samples than the random sampling method. For example, to achieve an AUC of 0.79, the random sampling method used 32 samples, while our best active learning algorithm required only 12 samples, a reduction of 62.5% in manual annotation effort. PMID:22127105

Parallel grid library for rapid and flexible simulation development

NASA Astrophysics Data System (ADS)

Honkonen, I.; von Alfthan, S.; Sandroos, A.; Janhunen, P.; Palmroth, M.

2013-04-01

We present an easy to use and flexible grid library for developing highly scalable parallel simulations. The distributed cartesian cell-refinable grid (dccrg) supports adaptive mesh refinement and allows an arbitrary C++ class to be used as cell data. The amount of data in grid cells can vary both in space and time allowing dccrg to be used in very different types of simulations, for example in fluid and particle codes. Dccrg transfers the data between neighboring cells on different processes transparently and asynchronously allowing one to overlap computation and communication. This enables excellent scalability at least up to 32 k cores in magnetohydrodynamic tests depending on the problem and hardware. In the version of dccrg presented here part of the mesh metadata is replicated between MPI processes reducing the scalability of adaptive mesh refinement (AMR) to between 200 and 600 processes. Dccrg is free software that anyone can use, study and modify and is available at https://gitorious.org/dccrg. Users are also kindly requested to cite this work when publishing results obtained with dccrg. Catalogue identifier: AEOM_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOM_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: GNU Lesser General Public License version 3 No. of lines in distributed program, including test data, etc.: 54975 No. of bytes in distributed program, including test data, etc.: 974015 Distribution format: tar.gz Programming language: C++. Computer: PC, cluster, supercomputer. Operating system: POSIX. The code has been parallelized using MPI and tested with 1-32768 processes RAM: 10 MB-10 GB per process Classification: 4.12, 4.14, 6.5, 19.3, 19.10, 20. External routines: MPI-2 [1], boost [2], Zoltan [3], sfc++ [4] Nature of problem: Grid library supporting arbitrary data in grid cells, parallel adaptive mesh refinement, transparent remote neighbor data updates and load balancing. Solution method: The simulation grid is represented by an adjacency list (graph) with vertices stored into a hash table and edges into contiguous arrays. Message Passing Interface standard is used for parallelization. Cell data is given as a template parameter when instantiating the grid. Restrictions: Logically cartesian grid. Running time: Running time depends on the hardware, problem and the solution method. Small problems can be solved in under a minute and very large problems can take weeks. The examples and tests provided with the package take less than about one minute using default options. In the version of dccrg presented here the speed of adaptive mesh refinement is at most of the order of 106 total created cells per second. http://www.mpi-forum.org/. http://www.boost.org/. K. Devine, E. Boman, R. Heaphy, B. Hendrickson, C. Vaughan, Zoltan data management services for parallel dynamic applications, Comput. Sci. Eng. 4 (2002) 90-97. http://dx.doi.org/10.1109/5992.988653. https://gitorious.org/sfc++.

The contribution of the vaccine adverse event text mining system to the classification of possible Guillain-Barré syndrome reports.

PubMed

Botsis, T; Woo, E J; Ball, R

2013-01-01

We previously demonstrated that a general purpose text mining system, the Vaccine adverse event Text Mining (VaeTM) system, could be used to automatically classify reports of an-aphylaxis for post-marketing safety surveillance of vaccines. To evaluate the ability of VaeTM to classify reports to the Vaccine Adverse Event Reporting System (VAERS) of possible Guillain-Barré Syndrome (GBS). We used VaeTM to extract the key diagnostic features from the text of reports in VAERS. Then, we applied the Brighton Collaboration (BC) case definition for GBS, and an information retrieval strategy (i.e. the vector space model) to quantify the specific information that is included in the key features extracted by VaeTM and compared it with the encoded information that is already stored in VAERS as Medical Dictionary for Regulatory Activities (MedDRA) Preferred Terms (PTs). We also evaluated the contribution of the primary (diagnosis and cause of death) and secondary (second level diagnosis and symptoms) diagnostic VaeTM-based features to the total VaeTM-based information. MedDRA captured more information and better supported the classification of reports for GBS than VaeTM (AUC: 0.904 vs. 0.777); the lower performance of VaeTM is likely due to the lack of extraction by VaeTM of specific laboratory results that are included in the BC criteria for GBS. On the other hand, the VaeTM-based classification exhibited greater specificity than the MedDRA-based approach (94.96% vs. 87.65%). Most of the VaeTM-based information was contained in the secondary diagnostic features. For GBS, clinical signs and symptoms alone are not sufficient to match MedDRA coding for purposes of case classification, but are preferred if specificity is the priority.

Capu and Spire assemble a cytoplasmic actin mesh that maintains microtubule organization in the Drosophila oocyte.

PubMed

Dahlgaard, Katja; Raposo, Alexandre A S F; Niccoli, Teresa; St Johnston, Daniel

2007-10-01

Mutants in the actin nucleators Cappuccino and Spire disrupt the polarized microtubule network in the Drosophila oocyte that defines the anterior-posterior axis, suggesting that microtubule organization depends on actin. Here, we show that Cappuccino and Spire organize an isotropic mesh of actin filaments in the oocyte cytoplasm. capu and spire mutants lack this mesh, whereas overexpressed truncated Cappuccino stabilizes the mesh in the presence of Latrunculin A and partially rescues spire mutants. Spire overexpression cannot rescue capu mutants, but prevents actin mesh disassembly at stage 10B and blocks late cytoplasmic streaming. We also show that the actin mesh regulates microtubules indirectly, by inhibiting kinesin-dependent cytoplasmic flows. Thus, the Capu pathway controls alternative states of the oocyte cytoplasm: when active, it assembles an actin mesh that suppresses kinesin motility to maintain a polarized microtubule cytoskeleton. When inactive, unrestrained kinesin movement generates flows that wash microtubules to the cortex.

Fog Harvesting with Harps.

PubMed

Shi, Weiwei; Anderson, Mark J; Tulkoff, Joshua B; Kennedy, Brook S; Boreyko, Jonathan B

2018-04-11

Fog harvesting is a useful technique for obtaining fresh water in arid climates. The wire meshes currently utilized for fog harvesting suffer from dual constraints: coarse meshes cannot efficiently capture microscopic fog droplets, whereas fine meshes suffer from clogging issues. Here, we design and fabricate fog harvesters comprising an array of vertical wires, which we call "fog harps". Under controlled laboratory conditions, the fog-harvesting rates for fog harps with three different wire diameters were compared to conventional meshes of equivalent dimensions. As expected for the mesh structures, the mid-sized wires exhibited the largest fog collection rate, with a drop-off in performance for the fine or coarse meshes. In contrast, the fog-harvesting rate continually increased with decreasing wire diameter for the fog harps due to efficient droplet shedding that prevented clogging. This resulted in a 3-fold enhancement in the fog-harvesting rate for the harp design compared to an equivalent mesh.

50 CFR 229.35 - Bottlenose Dolphin Take Reduction Plan.

Code of Federal Regulations, 2010 CFR

2010-10-01

... a gillnet constructed with a mesh size greater than or equal to 7-inches (17.8 cm) stretched mesh... less than 7-inches (17.8 cm) stretched mesh. New Jersey, Delaware, and Maryland State waters means the...) stretched mesh. South Carolina, Georgia, and Florida waters means the area consisting of all marine and...

50 CFR 229.35 - Bottlenose Dolphin Take Reduction Plan.

Code of Federal Regulations, 2011 CFR

2011-10-01

... a gillnet constructed with a mesh size greater than or equal to 7-inches (17.8 cm) stretched mesh... less than 7-inches (17.8 cm) stretched mesh. New Jersey, Delaware, and Maryland State waters means the...) stretched mesh. South Carolina, Georgia, and Florida waters means the area consisting of all marine and...

50 CFR 229.35 - Bottlenose Dolphin Take Reduction Plan.

Code of Federal Regulations, 2012 CFR

2012-10-01

... a gillnet constructed with a mesh size greater than or equal to 7-inches (17.8 cm) stretched mesh... less than 7-inches (17.8 cm) stretched mesh. New Jersey, Delaware, and Maryland State waters means the...) stretched mesh. South Carolina, Georgia, and Florida waters means the area consisting of all marine and...

50 CFR 229.35 - Bottlenose Dolphin Take Reduction Plan.

Code of Federal Regulations, 2014 CFR

2014-10-01

... means a gillnet constructed with a mesh size greater than or equal to 7-inches (17.8 cm) stretched mesh... less than 7-inches (17.8 cm) stretched mesh. New Jersey, Delaware, and Maryland State waters means the...) stretched mesh. South Carolina, Georgia, and Florida waters means the area consisting of all marine and...

50 CFR 229.35 - Bottlenose Dolphin Take Reduction Plan.

Code of Federal Regulations, 2013 CFR

2013-10-01

... means a gillnet constructed with a mesh size greater than or equal to 7-inches (17.8 cm) stretched mesh... less than 7-inches (17.8 cm) stretched mesh. New Jersey, Delaware, and Maryland State waters means the...) stretched mesh. South Carolina, Georgia, and Florida waters means the area consisting of all marine and...

A Survey of Solver-Related Geometry and Meshing Issues

NASA Technical Reports Server (NTRS)

Masters, James; Daniel, Derick; Gudenkauf, Jared; Hine, David; Sideroff, Chris

2016-01-01

There is a concern in the computational fluid dynamics community that mesh generation is a significant bottleneck in the CFD workflow. This is one of several papers that will help set the stage for a moderated panel discussion addressing this issue. Although certain general "rules of thumb" and a priori mesh metrics can be used to ensure that some base level of mesh quality is achieved, inadequate consideration is often given to the type of solver or particular flow regime on which the mesh will be utilized. This paper explores how an analyst may want to think differently about a mesh based on considerations such as if a flow is compressible vs. incompressible or hypersonic vs. subsonic or if the solver is node-centered vs. cell-centered. This paper is a high-level investigation intended to provide general insight into how considering the nature of the solver or flow when performing mesh generation has the potential to increase the accuracy and/or robustness of the solution and drive the mesh generation process to a state where it is no longer a hindrance to the analysis process.

Towards a new multiscale air quality transport model using the fully unstructured anisotropic adaptive mesh technology of Fluidity (version 4.1.9)

NASA Astrophysics Data System (ADS)

Zheng, J.; Zhu, J.; Wang, Z.; Fang, F.; Pain, C. C.; Xiang, J.

2015-10-01

An integrated method of advanced anisotropic hr-adaptive mesh and discretization numerical techniques has been, for first time, applied to modelling of multiscale advection-diffusion problems, which is based on a discontinuous Galerkin/control volume discretization on unstructured meshes. Over existing air quality models typically based on static-structured grids using a locally nesting technique, the advantage of the anisotropic hr-adaptive model has the ability to adapt the mesh according to the evolving pollutant distribution and flow features. That is, the mesh resolution can be adjusted dynamically to simulate the pollutant transport process accurately and effectively. To illustrate the capability of the anisotropic adaptive unstructured mesh model, three benchmark numerical experiments have been set up for two-dimensional (2-D) advection phenomena. Comparisons have been made between the results obtained using uniform resolution meshes and anisotropic adaptive resolution meshes. Performance achieved in 3-D simulation of power plant plumes indicates that this new adaptive multiscale model has the potential to provide accurate air quality modelling solutions effectively.

Highly flexible transparent electrodes based on mesh-patterned rigid indium tin oxide.

PubMed

Sakamoto, Kosuke; Kuwae, Hiroyuki; Kobayashi, Naofumi; Nobori, Atsuki; Shoji, Shuichi; Mizuno, Jun

2018-02-12

We developed highly bendable transparent indium tin oxide (ITO) electrodes with a mesh pattern for use in flexible electronic devices. The mesh patterns lowered tensile stress and hindered propagation of cracks. Simulations using the finite element method confirmed that the mesh patterns decreased tensile stress by over 10% because of the escaped strain to the flexible film when the electrodes were bent. The proposed patterned ITO electrodes were simply fabricated by photolithography and wet etching. The resistance increase ratio of a mesh-patterned ITO electrode after bending 1000 times was at least two orders of magnitude lower than that of a planar ITO electrode. In addition, crack propagation was stopped by the mesh pattern of the patterned ITO electrode. A mesh-patterned ITO electrode was used in a liquid-based organic light-emitting diode (OLED). The OLED displayed the same current density-voltage-luminance (J-V-L) curves before and after bending 100 times. These results indicate that the developed mesh-patterned ITO electrodes are attractive for use in flexible electronic devices.

Assigning categorical information to Japanese medical terms using MeSH and MEDLINE.

PubMed

Onogi, Yuzo

2007-01-01

This paper reports on the assigning of MeSH (Medical Subject Headings) categories to Japanese terms in an English-Japanese dictionary using the titles and abstracts of articles indexed in MEDLINE. In a previous study, 30,000 of 80,000 terms in the dictionary were mapped to MeSH terms by normalized comparison. It was reasoned that if the remaining dictionary terms appeared in MEDLINE-indexed articles that are indexed using MeSH terms, then relevancies between the dictionary terms and MeSH terms could be calculated, and thus MeSH categories assigned. This study compares two approaches for calculating the weight matrix. One is the TF*IDF method and the other uses the inner product of two weight matrices. About 20,000 additional dictionary terms were identified in MEDLINE-indexed articles published between 2000 and 2004. The precision and recall of these algorithms were evaluated separately for MeSH terms and non-MeSH terms. Unfortunately, the precision and recall of the algorithms was not good, but this method will help with manual assignment of MeSH categories to dictionary terms.

In vivo response to polypropylene following implantation in animal models: a review of biocompatibility.

PubMed

Kelly, Michelle; Macdougall, Katherine; Olabisi, Oluwafisayo; McGuire, Neil

2017-02-01

Polypropylene is a material that is commonly used to treat pelvic floor conditions such as pelvic organ prolapse (POP) and stress urinary incontinence (SUI). Owing to the nature of complications experienced by some patients implanted with either incontinence or prolapse meshes, the biocompatibility of polypropylene has recently been questioned. This literature review considers the in vivo response to polypropylene following implantation in animal models. The specific areas explored in this review are material selection, impact of anatomical location, and the structure, weight and size of polypropylene mesh types. All relevant abstracts from original articles investigating the host response of mesh in vivo were reviewed. Papers were obtained and categorised into various mesh material types: polypropylene, polypropylene composites, and other synthetic and biologically derived mesh. Polypropylene mesh fared well in comparison with other material types in terms of host response. It was found that a lightweight, large-pore mesh is the most appropriate structure. The evidence reviewed shows that polypropylene evokes a less inflammatory or similar host response when compared with other materials used in mesh devices.

The MeSH translation maintenance system: structure, interface design, and implementation.

PubMed

Nelson, Stuart J; Schopen, Michael; Savage, Allan G; Schulman, Jacque-Lynne; Arluk, Natalie

2004-01-01

The National Library of Medicine (NLM) produces annual editions of the Medical Subject Headings (MeSH). Translations of MeSH are often done to make the vocabulary useful for non-English users. However, MeSH translators have encountered difficulties with entry vocabulary as they maintain and update their translation. Tracking MeSH changes and updating their translations in a reasonable time frame is cumbersome. NLM has developed and implemented a concept-centered vocabulary maintenance system for MeSH. This system has been extended to create an interlingual database of translations, the MeSH Translation Maintenance System (MTMS). This database allows continual updating of the translations, as well as facilitating tracking of the changes within MeSH from one year to another. The MTMS interface uses a Web-based design with multiple colors and fonts to indicate concepts needing translation or review. Concepts for which there is no exact English equivalent can be added. The system software encourages compliance with the Unicode standard in order to ensure that character sets with native alphabets and full orthography are used consistently.

Laser-structured Janus wire mesh for efficient oil-water separation.

PubMed

Liu, Yu-Qing; Han, Dong-Dong; Jiao, Zhi-Zhen; Liu, Yan; Jiang, Hao-Bo; Wu, Xuan-Hang; Ding, Hong; Zhang, Yong-Lai; Sun, Hong-Bo

2017-11-23

We report here the fabrication of a Janus wire mesh by a combined process of laser structuring and fluorosilane/graphene oxide (GO) modification of the two sides of the mesh, respectively, toward its applications in efficient oil/water separation. Femtosecond laser processing has been employed to make different laser-induced periodic surface structures (LIPSS) on each side of the mesh. Surface modification with fluorosilane on one side and GO on the other side endows the two sides of the Janus mesh with distinct wettability. Thus, one side is superhydrophobic and superoleophilic in air, and the other side is superhydrophilic in air and superoleophobic under water. As a proof of concept, we demonstrated the separation of light/heavy oil and water mixtures using this Janus mesh. To realize an efficient separation, the intrusion pressure that is dominated by the wire mesh framework and the wettability should be taken into account. Our strategy may open up a new way to design and fabricate Janus structures with distinct wettability; and the resultant Janus mesh may find broad applications in the separation of oil contaminants from water.

Generating Automated Text Complexity Classifications That Are Aligned with Targeted Text Complexity Standards. Research Report. ETS RR-10-28

ERIC Educational Resources Information Center

Sheehan, Kathleen M.; Kostin, Irene; Futagi, Yoko; Flor, Michael

2010-01-01

The Common Core Standards call for students to be exposed to a much greater level of text complexity than has been the norm in schools for the past 40 years. Textbook publishers, teachers, and assessment developers are being asked to refocus materials and methods to ensure that students are challenged to read texts at steadily increasing…

Investigation into Text Classification With Kernel Based Schemes

DTIC Science & Technology

2010-03-01

Document Matrix TDMs Term-Document Matrices TMG Text to Matrix Generator TN True Negative TP True Positive VSM Vector Space Model xxii THIS PAGE...are represented as a term-document matrix, common evaluation metrics, and the software package Text to Matrix Generator ( TMG ). The classifier...AND METRICS This chapter introduces the indexing capabilities of the Text to Matrix Generator ( TMG ) Toolbox. Specific attention is placed on the

Automated segmentation of geographic atrophy in fundus autofluorescence images using supervised pixel classification.

PubMed

Hu, Zhihong; Medioni, Gerard G; Hernandez, Matthias; Sadda, Srinivas R

2015-01-01

Geographic atrophy (GA) is a manifestation of the advanced or late stage of age-related macular degeneration (AMD). AMD is the leading cause of blindness in people over the age of 65 in the western world. The purpose of this study is to develop a fully automated supervised pixel classification approach for segmenting GA, including uni- and multifocal patches in fundus autofluorescene (FAF) images. The image features include region-wise intensity measures, gray-level co-occurrence matrix measures, and Gaussian filter banks. A [Formula: see text]-nearest-neighbor pixel classifier is applied to obtain a GA probability map, representing the likelihood that the image pixel belongs to GA. Sixteen randomly chosen FAF images were obtained from 16 subjects with GA. The algorithm-defined GA regions are compared with manual delineation performed by a certified image reading center grader. Eight-fold cross-validation is applied to evaluate the algorithm performance. The mean overlap ratio (OR), area correlation (Pearson's [Formula: see text]), accuracy (ACC), true positive rate (TPR), specificity (SPC), positive predictive value (PPV), and false discovery rate (FDR) between the algorithm- and manually defined GA regions are [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], respectively.

Evaluation of mechanical properties in metal wire mesh supported selective catalytic reduction (SCR) catalyst structures

NASA Astrophysics Data System (ADS)

Rajath, S.; Siddaraju, C.; Nandakishora, Y.; Roy, Sukumar

2018-04-01

The objective of this research is to evaluate certain specific mechanical properties of certain stainless steel wire mesh supported Selective catalytic reduction catalysts structures wherein the physical properties of the metal wire mesh and also its surface treatments played vital role thereby influencing the mechanical properties. As the adhesion between the stainless steel wire mesh and the catalyst material determines the bond strength and the erosion resistance of catalyst structures, surface modifications of the metal- wire mesh structure in order to facilitate the interface bonding is therefore very important to realize enhanced level of mechanical properties. One way to enhance such adhesion properties, the stainless steel wire mesh is treated with the various acids, i.e., chromic acid, phosphoric acid including certain mineral acids and combination of all those in various molar ratios that could generate surface active groups on metal surface that promotes good interface structure between the metal- wire mesh and metal oxide-based catalyst material and then the stainless steel wire mesh is dipped in the glass powder slurry containing some amount of organic binder. As a result of which the said catalyst material adheres to the metal-wire mesh surface more effectively that improves the erosion profile of supported catalysts structure including bond strength.

Scalable L-infinite coding of meshes.

PubMed

Munteanu, Adrian; Cernea, Dan C; Alecu, Alin; Cornelis, Jan; Schelkens, Peter

2010-01-01

The paper investigates the novel concept of local-error control in mesh geometry encoding. In contrast to traditional mesh-coding systems that use the mean-square error as target distortion metric, this paper proposes a new L-infinite mesh-coding approach, for which the target distortion metric is the L-infinite distortion. In this context, a novel wavelet-based L-infinite-constrained coding approach for meshes is proposed, which ensures that the maximum error between the vertex positions in the original and decoded meshes is lower than a given upper bound. Furthermore, the proposed system achieves scalability in L-infinite sense, that is, any decoding of the input stream will correspond to a perfectly predictable L-infinite distortion upper bound. An instantiation of the proposed L-infinite-coding approach is demonstrated for MESHGRID, which is a scalable 3D object encoding system, part of MPEG-4 AFX. In this context, the advantages of scalable L-infinite coding over L-2-oriented coding are experimentally demonstrated. One concludes that the proposed L-infinite mesh-coding approach guarantees an upper bound on the local error in the decoded mesh, it enables a fast real-time implementation of the rate allocation, and it preserves all the scalability features and animation capabilities of the employed scalable mesh codec.

Variations in Medical Subject Headings (MeSH) mapping: from the natural language of patron terms to the controlled vocabulary of mapped lists*

PubMed Central

Gault, Lora V.; Shultz, Mary; Davies, Kathy J.

2002-01-01

Objectives: This study compared the mapping of natural language patron terms to the Medical Subject Headings (MeSH) across six MeSH interfaces for the MEDLINE database. Methods: Test data were obtained from search requests submitted by patrons to the Library of the Health Sciences, University of Illinois at Chicago, over a nine-month period. Search request statements were parsed into separate terms or phrases. Using print sources from the National Library of Medicine, Each parsed patron term was assigned corresponding MeSH terms. Each patron term was entered into each of the selected interfaces to determine how effectively they mapped to MeSH. Data were collected for mapping success, accessibility of MeSH term within mapped list, and total number of MeSH choices within each list. Results: The selected MEDLINE interfaces do not map the same patron term in the same way, nor do they consistently lead to what is considered the appropriate MeSH term. Conclusions: If searchers utilize the MEDLINE database to its fullest potential by mapping to MeSH, the results of the mapping will vary between interfaces. This variance may ultimately impact the search results. These differences should be considered when choosing a MEDLINE interface and when instructing end users. PMID:11999175

Applications of Space-Filling-Curves to Cartesian Methods for CFD

NASA Technical Reports Server (NTRS)

Aftosmis, Michael J.; Berger, Marsha J.; Murman, Scott M.

2003-01-01

The proposed paper presents a variety novel uses of Space-Filling-Curves (SFCs) for Cartesian mesh methods in 0. While these techniques will be demonstrated using non-body-fitted Cartesian meshes, most are applicable on general body-fitted meshes -both structured and unstructured. We demonstrate the use of single O(N log N) SFC-based reordering to produce single-pass (O(N)) algorithms for mesh partitioning, multigrid coarsening, and inter-mesh interpolation. The intermesh interpolation operator has many practical applications including warm starts on modified geometry, or as an inter-grid transfer operator on remeshed regions in moving-body simulations. Exploiting the compact construction of these operators, we further show that these algorithms are highly amenable to parallelization. Examples using the SFC-based mesh partitioner show nearly linear speedup to 512 CPUs even when using multigrid as a smoother. Partition statistics are presented showing that the SFC partitions are, on-average, within 10% of ideal even with only around 50,000 cells in each subdomain. The inter-mesh interpolation operator also has linear asymptotic complexity and can be used to map a solution with N unknowns to another mesh with M unknowns with O(max(M,N)) operations. This capability is demonstrated both on moving-body simulations and in mapping solutions to perturbed meshes for finite-difference-based gradient design methods.

Variations in Medical Subject Headings (MeSH) mapping: from the natural language of patron terms to the controlled vocabulary of mapped lists.

PubMed

Gault, Lora V; Shultz, Mary; Davies, Kathy J

2002-04-01

This study compared the mapping of natural language patron terms to the Medical Subject Headings (MeSH) across six MeSH interfaces for the MEDLINE database. Test data were obtained from search requests submitted by patrons to the Library of the Health Sciences, University of Illinois at Chicago, over a nine-month period. Search request statements were parsed into separate terms or phrases. Using print sources from the National Library of Medicine, Each parsed patron term was assigned corresponding MeSH terms. Each patron term was entered into each of the selected interfaces to determine how effectively they mapped to MeSH. Data were collected for mapping success, accessibility of MeSH term within mapped list, and total number of MeSH choices within each list. The selected MEDLINE interfaces do not map the same patron term in the same way, nor do they consistently lead to what is considered the appropriate MeSH term. If searchers utilize the MEDLINE database to its fullest potential by mapping to MeSH, the results of the mapping will vary between interfaces. This variance may ultimately impact the search results. These differences should be considered when choosing a MEDLINE interface and when instructing end users.

A matrix dependent/algebraic multigrid approach for extruded meshes with applications to ice sheet modeling

DOE PAGES

Tuminaro, Raymond S.; Perego, Mauro; Tezaur, Irina Kalashnikova; ...

2016-10-06

A multigrid method is proposed that combines ideas from matrix dependent multigrid for structured grids and algebraic multigrid for unstructured grids. It targets problems where a three-dimensional mesh can be viewed as an extrusion of a two-dimensional, unstructured mesh in a third dimension. Our motivation comes from the modeling of thin structures via finite elements and, more specifically, the modeling of ice sheets. Extruded meshes are relatively common for thin structures and often give rise to anisotropic problems when the thin direction mesh spacing is much smaller than the broad direction mesh spacing. Within our approach, the first few multigridmore » hierarchy levels are obtained by applying matrix dependent multigrid to semicoarsen in a structured thin direction fashion. After sufficient structured coarsening, the resulting mesh contains only a single layer corresponding to a two-dimensional, unstructured mesh. Algebraic multigrid can then be employed in a standard manner to create further coarse levels, as the anisotropic phenomena is no longer present in the single layer problem. The overall approach remains fully algebraic, with the minor exception that some additional information is needed to determine the extruded direction. Furthermore, this facilitates integration of the solver with a variety of different extruded mesh applications.« less

Adaptive mesh refinement and load balancing based on multi-level block-structured Cartesian mesh

NASA Astrophysics Data System (ADS)

Misaka, Takashi; Sasaki, Daisuke; Obayashi, Shigeru

2017-11-01

We developed a framework for a distributed-memory parallel computer that enables dynamic data management for adaptive mesh refinement and load balancing. We employed simple data structure of the building cube method (BCM) where a computational domain is divided into multi-level cubic domains and each cube has the same number of grid points inside, realising a multi-level block-structured Cartesian mesh. Solution adaptive mesh refinement, which works efficiently with the help of the dynamic load balancing, was implemented by dividing cubes based on mesh refinement criteria. The framework was investigated with the Laplace equation in terms of adaptive mesh refinement, load balancing and the parallel efficiency. It was then applied to the incompressible Navier-Stokes equations to simulate a turbulent flow around a sphere. We considered wall-adaptive cube refinement where a non-dimensional wall distance y+ near the sphere is used for a criterion of mesh refinement. The result showed the load imbalance due to y+ adaptive mesh refinement was corrected by the present approach. To utilise the BCM framework more effectively, we also tested a cube-wise algorithm switching where an explicit and implicit time integration schemes are switched depending on the local Courant-Friedrichs-Lewy (CFL) condition in each cube.

Surface modification of polypropylene mesh devices with cyclodextrin via cold plasma for hernia repair: Characterization and antibacterial properties

NASA Astrophysics Data System (ADS)

Sanbhal, Noor; Mao, Ying; Sun, Gang; Xu, Rui Fang; Zhang, Qian; Wang, Lu

2018-05-01

Light weight polypropylene (PP) mesh is the most widely used implant among all other synthetic meshes for hernia repair. However, infection is the complication associated to all synthetic meshes after hernia repair. Thus, to manage mesh related infection; antibacterial drug is generally loaded to surgical implants to supply drug locally in mesh implanted site. Nevertheless, PP mesh restricts the loading of antibacterial drug at operated area due to its low wettability. The aim of this study was to introduce a novel antimicrobial PP mesh modified with β-cyclodextrine (CD) and loaded with antimicrobial agent for infection prevention. A cold oxygen plasma treatment was able to activate the surfaces of polypropylene fibers, and then CD was incorporated onto the surfaces of PP fibers. Afterward, triclosan, as a model antibacterial agent, was loaded into CD cavity to provide desired antibacterial functions. The modified polypropylene mesh samples CD-Tric-1, CD-Tric-3 exhibited excellent inhibition zone and continuous antibacterial efficacy against E. coli and S. aureus up to 6 and 7 days respectively. Results of AFM, SEM, FTIR and antibacterial tests evidenced that oxygen plasma process is necessary to increase chemical connection between CD molecules and PP fibers. The samples were also characterized by using EDX, XRD, TGA, DSC and water contact angle.

Long-term anisotropic mechanical response of surgical meshes used to repair abdominal wall defects.

PubMed

Hernández-Gascón, B; Peña, E; Pascual, G; Rodríguez, M; Bellón, J M; Calvo, B

2012-01-01

Routine hernia repair surgery involves the implant of synthetic mesh. However, this type of procedure may give rise to pain and bowel incarceration and strangulation, causing considerable patient disability. The purpose of this study was to compare the long-term behaviour of three commercial meshes used to repair the partially herniated abdomen in New Zealand White rabbits: the heavyweight (HW) mesh, Surgipro(®) and lightweight (LW) mesh, Optilene(®), both made of polypropylene (PP), and a mediumweight (MW) mesh, Infinit(®), made of polytetrafluoroethylene (PTFE). The implanted meshes were mechanical and histological assessed at 14, 90 and 180 days post-implant. This behaviour was compared to the anisotropic mechanical behaviour of the unrepaired abdominal wall in control non-operated rabbits. Both uniaxial mechanical tests conducted in craneo-caudal and perpendicular directions and histological findings revealed substantial collagen growth over the repaired hernial defects causing stiffness in the repair zone, and thus a change in the original properties of the meshes. The mechanical behaviour of the healthy tissue in the craneo-caudal direction was not reproduced by any of the implanted meshes after 14 days or 90 days of implant, whereas in the perpendicular direction, SUR and OPT achieved similar behaviour. From a mechanical standpoint, the anisotropic PP-lightweight meshes may be considered a good choice in the long run, which correlates with the structure of the regenerated tissue. Copyright © 2011 Elsevier Ltd. All rights reserved.

Vietnamese Document Representation and Classification

NASA Astrophysics Data System (ADS)

Nguyen, Giang-Son; Gao, Xiaoying; Andreae, Peter

Vietnamese is very different from English and little research has been done on Vietnamese document classification, or indeed, on any kind of Vietnamese language processing, and only a few small corpora are available for research. We created a large Vietnamese text corpus with about 18000 documents, and manually classified them based on different criteria such as topics and styles, giving several classification tasks of different difficulty levels. This paper introduces a new syllable-based document representation at the morphological level of the language for efficient classification. We tested the representation on our corpus with different classification tasks using six classification algorithms and two feature selection techniques. Our experiments show that the new representation is effective for Vietnamese categorization, and suggest that best performance can be achieved using syllable-pair document representation, an SVM with a polynomial kernel as the learning algorithm, and using Information gain and an external dictionary for feature selection.

Short-term complications associated with the use of transvaginal mesh in pelvic floor reconstructive surgery: Results from a multi-institutional prospectively maintained dataset.

PubMed

Caveney, Maxx; Haddad, Devin; Matthews, Catherine; Badlani, Gopal; Mirzazadeh, Majid

2017-11-01

Vaginal reconstructive surgery can be performed with or without mesh. We sought to determine comparative rates of perioperative complications of native tissue versus vaginal mesh repairs for pelvic organ prolapse. Using the National Surgical Quality Improvement Program (NSQIP) database, we concatenated surgical data from vaginal procedures for prolapse repair, including anterior and posterior colporrhaphy, paravaginal defect repair, enterocele repair, and vaginal colpopexy using Current Procedural Terminology (CPT) coding. We stratified this data by the modifier associated with mesh usage at the time of the procedure. We then compared 30-day perioperative outcomes, postoperative complications (bleeding, infection, etc), and readmission rates between women with and without mesh-based repairs. We identified 10 657 vaginal reconstructive procedures without mesh and 959 mesh-based repairs from 2009 through 2013. Patients undergoing mesh repair were more likely to experience at least one complication than native tissue repair (9.28% vs 6.15%, P < 0.001), with the overall complication rate also being higher in the mesh group (11.37% vs 9.39%, P = 0.03). Procedures with mesh had a higher rate of perioperative bleeding requiring transfusion than native tissue repair (2.3% vs 0.49%, P < 0.001), and organ surgical site infection (SSI) (0.52% vs 0.17%, P = 0.02). There were no significant differences in rates of readmission, superficial, or deep SSIs, pneumonia, urinary tract infection, sepsis, or renal failure. The use of vaginal mesh for pelvic organ prolapse repair appears to result in a higher rate of perioperative complications than native tissue repair. Patients undergoing these procedures should be counselled preoperatively concerning these risks. © 2017 Wiley Periodicals, Inc.

Cost effectiveness of mesh prophylaxis to prevent parastomal hernia in patients undergoing permanent colostomy for rectal cancer.

PubMed

Lee, Lawrence; Saleem, Abdulaziz; Landry, Tara; Latimer, Eric; Chaudhury, Prosanto; Feldman, Liane S

2014-01-01

Parastomal hernia (PSH) is common after stoma formation. Studies have reported that mesh prophylaxis reduces PSH, but there are no cost-effectiveness data. Our objective was to determine the cost effectiveness of mesh prophylaxis vs no prophylaxis to prevent PSH in patients undergoing abdominoperineal resection with permanent colostomy for rectal cancer. Using a cohort Markov model, we modeled the costs and effectiveness of mesh prophylaxis vs no prophylaxis at the index operation in a cohort of 60-year-old patients undergoing abdominoperineal resection for rectal cancer during a time horizon of 5 years. Costs were expressed in 2012 Canadian dollars (CAD$) and effectiveness in quality-adjusted life years. Deterministic and probabilistic sensitivity analyses were performed. In patients with stage I to III rectal cancer, prophylactic mesh was dominant (less costly and more effective) compared with no mesh. In patients with stage IV disease, mesh prophylaxis was associated with higher cost (CAD$495 more) and minimally increased effectiveness (0.05 additional quality-adjusted life years), resulting in an incremental cost-effectiveness ratio of CAD$10,818 per quality-adjusted life year. On sensitivity analyses, the decision was sensitive to the probability of mesh infection and the cost of the mesh, and method of diagnosing PSH. In patients undergoing abdominoperineal resection with permanent colostomy for rectal cancer, mesh prophylaxis might be the less costly and more effective strategy compared with no mesh to prevent PSH in patients with stage I to III disease, and might be cost effective in patients with stage IV disease. Copyright © 2014 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Efficacy of Prophylactic Mesh in End-Colostomy Construction: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

PubMed

Wang, Shuanhu; Wang, Wenbin; Zhu, Bing; Song, Guolei; Jiang, Congqiao

2016-10-01

Parastomal hernia is a very common complication after colostomy, especially end-colostomy. It is unclear whether prophylactic placement of mesh at the time of stoma formation could prevent parastomal hernia formation after surgery for rectal cancer. A systematic review and meta-analysis were conducted to evaluate the efficacy of prophylactic mesh in end-colostomy construction. PubMed, Embase, and the Cochrane Library were searched, covering records entered from their inception to September 2015. Randomized controlled trials (RCTs) comparing stoma with mesh to stoma without mesh after surgery for rectal cancer were included. The primary outcome was the incidence of parastomal hernia. Pooled risk ratios (RR) with 95 % confidence intervals (CI) were obtained using random effects models. Six RCTs containing 309 patients were included. Parastomal hernia occurred in 24.4 % (38 of 156) of patients with mesh and 50.3 % (77 of 153) of patients without mesh. Meta-analysis showed a lower incidence of parastomal hernia (RR, 0.42; 95 % CI 0.22-0.82) and reoperation related to parastomal hernia (RR, 0.23; 95 % CI 0.06-0.89) in patients with mesh. Stoma-related morbidity was similar between mesh group and non-mesh group (RR, 0.65; 95 % CI 0.33-1.30). Prophylactic placement of a mesh at the time of a stoma formation seems to be associated with a significant reduction in the incidence of parastomal hernia and reoperation related to parastomal hernia after surgery for rectal cancer, but not the rate of stoma-related morbidity. However, the results should be interpreted with caution because of the heterogeneity among the studies.

Health-related quality of life and outcomes after surgical treatment of complications from vaginally placed mesh.

PubMed

Hokenstad, Erik D; El-Nashar, Sherif A; Blandon, Roberta E; Occhino, John A; Trabuco, Emanuel C; Gebhart, John B; Klingele, Christopher J

2015-01-01

We aimed to report on health-related quality of life after surgical excision of vaginally placed mesh for treatment of pelvic organ prolapse and to identify predictors of successful surgical management. We identified patients who underwent surgery for treatment of complications from vaginally placed mesh from January 1, 2003, through December 31, 2011, and conducted a follow-up survey. Logistic regression models were used to identify predictors of successful treatment. We identified 114 patients who underwent surgery for mesh-related complications and 68 underwent mesh excision. Of the 68 patients, 44 (64.7%) completed the survey. Of the 44 responders, 41 returned their consent form and were included in the analysis. Only 22 (54%) patients reported a successful outcome after mesh excision. Of 29 (71%) sexually active patients, 23 had dyspareunia before mesh excision and only 3 patients reported resolution of dyspareunia after excision. We reported a multivariable model for predicting successful surgical outcome with an area under the curve for the receiver operator characteristic of 0.781. In this model, complete excision of mesh, new overactive bladder symptoms after mesh placement, and a body mass index higher than 30 kg/m were associated with successful patient-reported outcomes; adjusted odds ratios (95% confidence intervals) were 5.46 (1.10-41.59), 7.76 (1.18-89.55), and 8.41 (1.35-92.41), respectively. Only half of the patients who had surgery for vaginally placed mesh complications reported improvement after surgery, with modest improvement in dyspareunia. Patients who had complete mesh excision, new overactive bladder symptoms, and obesity were more likely to report improvement.

Long-term follow-up of treatment for synthetic mesh complications.

PubMed

Hansen, Brooke L; Dunn, Guinn Ellen; Norton, Peggy; Hsu, Yvonne; Nygaard, Ingrid

2014-01-01

The objectives of this study are (1) to describe the presenting symptoms, findings, and treatment and (2) to describe the self-reported improvement and function at least 6 months after presentation in women presenting to 1 urogynecology division for complications associated with synthetic vaginal mesh. Women evaluated between 2006 and 2011 were identified by diagnostic codes. We abstracted information from the medical record and attempted to contact all women to complete a follow-up telephone survey questionnaire consisting of several validated instruments. A total of 111 women were evaluated for complications associated with synthetic vaginal mesh. The mean interval from index surgery was 2.4 years. Of these, 84% were referred from outside hospitals. Index surgeries included vaginal mesh kits/vaginally placed mesh (47%), midurethral mesh slings (37%), abdominally placed vaginal mesh (11%), and vaginal mesh kit with concomitantly placed mesh sling (5%). The most common complications were extrusion (65%), contraction (17%), and chronic pelvic pain (16%). A total of 98 women underwent some type of treatment (85 surgical) by urogynecologists, pelvic pain specialists, or physical therapists. Eighty-four (76%) provided follow-up information at mean interval since presentation of 2.3 years. At follow-up, the mean (SD) Pelvic Floor Distress Inventory score was 98 (67), the mean (SD) EQ-5D index score was 0.69 (0.23), and 22% reported vaginal discharge, 15% vaginal bleeding or spotting, and 45% sexual abstinence due to problems related to mesh. A total of 71% reported being overall better, whereas 29% were the same or worse. Two years after tertiary care level multidisciplinary treatment of vaginal mesh complications, many women still report symptoms that negatively impact their quality of life.

Transabdominal Preperitoneal Herniorrhaphy using Laser-Assisted Tissue Soldering in a Porcine Model

PubMed Central

Soltz, Barbara A.; Stadler, Istvan; Soltz, Robert

2009-01-01

Background and Objectives: Collagen solder is capable of fixation of surgical meshes during laparoscopic herniorrhaphy without compromising tissue integration, increasing adhesions or inflammation. This pilot study describes development of instrumentation and techniques for transabdominal preperitoneal (TAPP) herniorrhaphy using laser-assisted soldering technology. Methods: Anesthetized 20-kg to 25-kg female Yorkshire pigs underwent laparoscopy performed using a 3-trocar technique. Peritoneal incisions were made and pockets created in the preperitoneal space for mesh placement. Parietex TEC mesh segments embedded in 60% collagen-solder were soldered to the muscle surface by using a prototype laser (1.45µ, 4.5W CW, 5mm spot, and 55°C set temperature) and custom laparoscopic handpiece. Parietex TEC mesh segments (Control) were affixed to the muscle with fibrin sealant (Tisseel). Peritoneal closure was with staples (Control) or by soldering collagen embedded Vicryl mesh segments over the peritoneal incision (Mesh/TAPP). Segments were inserted using a specially designed introducer. Animals were recovered and underwent second-look laparoscopy at 6 weeks postimplantation. Mesh sites were harvested after animals were euthanized. Results: The mesh-solder constructs were easily inserted and affixed in the TAPP approach. Tisseel tended to drip during application, particularly in vertical and ventral locations. Postoperative healing was similar to Control segments in all cases. Mesh/TAPP closures healed without scarring or adhesion formation. Discussion and Conclusion: Collagen-based tissue soldering permits normal wound healing and may mitigate or reduce use of staples for laparoscopic mesh fixation and peritoneal closure. Laser-assisted mesh fixation and peritoneal closure is a promising alternative for laparoscopic herniorrhaphy. Further development of this strategy is warranted. PMID:19660214

Fog water collection effectiveness: Mesh intercomparisons

USGS Publications Warehouse

Fernandez, Daniel; Torregrosa, Alicia; Weiss-Penzias, Peter; Zhang, Bong June; Sorensen, Deckard; Cohen, Robert; McKinley, Gareth; Kleingartner, Justin; Oliphant, Andrew; Bowman, Matthew

2018-01-01

To explore fog water harvesting potential in California, we conducted long-term measurements involving three types of mesh using standard fog collectors (SFC). Volumetric fog water measurements from SFCs and wind data were collected and recorded in 15-minute intervals over three summertime fog seasons (2014–2016) at four California sites. SFCs were deployed with: standard 1.00 m2 double-layer 35% shade coefficient Raschel; stainless steel mesh coated with the MIT-14 hydrophobic formulation; and FogHa-Tin, a German manufactured, 3-dimensional spacer fabric deployed in two orientations. Analysis of 3419 volumetric samples from all sites showed strong relationships between mesh efficiency and wind speed. Raschel mesh collected 160% more fog water than FogHa-Tin at wind speeds less than 1 m s–1 and 45% less for wind speeds greater than 5 m s–1. MIT-14 coated stainless-steel mesh collected more fog water than Raschel mesh at all wind speeds. At low wind speeds of < 1 m s–1 the coated stainless steel mesh collected 3% more and at wind speeds of 4–5 m s–1, it collected 41% more. FogHa-Tin collected 5% more fog water when the warp of the weave was oriented vertically, per manufacturer specification, than when the warp of the weave was oriented horizontally. Time series measurements of three distinct mesh across similar wind regimes revealed inconsistent lags in fog water collection and inconsistent performance. Since such differences occurred under similar wind-speed regimes, we conclude that other factors play important roles in mesh performance, including in-situ fog event and aerosol dynamics that affect droplet-size spectra and droplet-to-mesh surface interactions.

Lack of size selectivity for paddlefish captured in hobbled gillnets

USGS Publications Warehouse

Scholten, G.D.; Bettoli, P.W.

2007-01-01

A commercial fishery for paddlefish Polyodon spathula caviar exists in Kentucky Lake, a reservoir on the lower Tennessee River. A 152-mm (bar-measure) minimum mesh size restriction on entanglement gear was enacted in 2002 and the minimum size limit was increased to 864 mm eye-fork length to reduce the possibility of recruitment overfishing. Paddlefish were sampled in 2003-2004 using experimental monofilament gillnets with panels of 89, 102, 127, 152, 178, and 203-mm meshes and the efficacy of the mesh size restriction was evaluated. Following the standards of commercial gear used in that fishery, nets were "hobbled" (i.e., 128 m ?? 3.6 m nets were tied down to 2.4 m; 91 m ?? 9.1 m nets were tied down to 7.6 m). The mean lengths of paddlefish (Ntotal = 576 fish) captured in each mesh were similar among most meshes and bycatch rates of sublegal fish did not vary with mesh size. Selectivity curves could not be modeled because the mean and modal lengths of fish captured in each mesh did not increase with mesh size. Ratios of fish girth to mesh perimeter (G:P) for individual fish were often less than 1.0 as a result of the largest meshes capturing small paddlefish. It is unclear whether lack of size selectivity for paddlefish was because the gillnets were hobbled, the unique morphology of paddlefish, or the fact that they swim with their mouths agape when filter feeding. The lack of size selectivity by hobbled gillnets fished in Kentucky Lake means that managers cannot influence the size of paddlefish captured by commercial gillnet gear by changing minimum mesh size regulations. ?? 2006 Elsevier B.V. All rights reserved.

Resterilized mesh in repair of abdominal wall defects in rats.

PubMed

Sucullu, Ilker; Akin, Mehmet Levhi; Yitgin, Selahattin; Filiz, Ali Ilker; Kurt, Yavuz

2008-01-01

A variety of negative opinions about repeated usage of relatively expensive resterilized synthetic meshes have been considered. It had been stated that resterilized polypropylene meshes inhibits fibroblastic activity, decreases proliferative activity, and increases apoptosis in human fibroblast culture, in vitro. The purpose of this study is the in vivo evaluation of the resterilized mesh repairs of abdominal hernia defects in rat models of incisional hernia by comparing primer repair and original mesh repairs. The rats (n = 22) were separated into three groups. While the abdominal defect was repaired by primary suture in the control group (CG), the defects were repaired by original mesh (OG) or resterilized mesh (RG) in mesh-repaired groups. After 21 days, the rats were evaluated for tissue tensile strengths, tissue hydroxyproline levels, tissue inflammation, fibrosis, and apoptosis. Although the tensile strengths in OG and RG were significantly higher than those of CG (p < .05 and p < .05), there was no significant difference between two groups. The tissue hydroxyproline levels in OG and RG were also higher than those of CG. The difference was not significant between the two groups. The inflammation and fibrosis indexes in OG and RG were significantly higher than those of CG (p < .0001 for both), but there was no difference between groups. While the apoptosis index in OG and RG was also higher than that of CG (p < .0001 for both), there was no significant difference between OG and RG. The usage of resterilized mesh in abdominal wall repair did not reduce the tissue tensile strength, did not affect the tissue hydroxyproline levels, did not decrease the fibrosis, and did not increase the tissue inflammation and apoptosis. In conclusion, usage of resterilized meshes in abdominal wall defects was as safe as sterilized meshes.

Use of a novel silk mesh for ventral midline hernioplasty in a mare.

PubMed

Haupt, Jennifer; García-López, José M; Chope, Kate

2015-03-13

Ventral midline hernia formation following abdominal surgery in horses is an uncommon complication; however, it can have serious consequences leading to increased morbidity and mortality. Currently, mesh hernioplasty is the treatment of choice for large ventral midline hernias in horses to allow potential return to normal function. Complications following mesh hernioplasty using polypropylene or polyester mesh in horses can be serious and similar to complications seen in human patients, including persistent incisional drainage, mesh infection, hernia recurrence, intra-abdominal adhesions, mesh or body wall failure, recurrent abdominal pain (colic), and peritonitis. This report describes the use of a novel bioresorbable silk mesh for repair of a large ventral midline incisional hernia in a mature, 600-kg horse. To our knowledge, this is the first report of its kind in the literature. A 9-year-old, 600-kg Warmblood mare presented with a ventral midline hernia following emergency exploratory celiotomy 20 months prior. The mare was anesthetized and a hernioplasty was performed using a novel bioresorbable silk mesh (SERI(®) Surgical Scaffold; Allergan Medical, Boston, MA). No complications were encountered either intra- or postoperatively. The mare was discharged from the hospital at 3 days postoperatively in an abdominal support bandage. At 8 and 20 weeks postoperatively, ultrasonographic assessment showed evidence of tissue ingrowth within and around the mesh. The mare was able to be bred 2 years in a row, carrying both foals to full gestation with no complications. Following both foalings, the abdomen has maintained a normal contour with no evidence of hernia recurrence. Ventral abdominal hernias can be repaired in horses using a bioresorbable silk mesh, which provides adequate biomechanical strength while allowing for fibrous tissue ingrowth. The use of a bioresorbable silk mesh for the repair of ventral hernias can be considered as a realistic option as it potentially provides significant benefits over traditional non-resorbable mesh.

Polymer microfiber meshes facilitate cardiac differentiation of c-kit{sup +} human cardiac stem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kan, Lijuan; Thayer, Patrick; Fan, Huimin

Electrospun microfiber meshes have been shown to support the proliferation and differentiation of many types of stem cells, but the phenotypic fate of c-kit{sup +} human cardiac stem cells (hCSCs) have not been explored. To this end, we utilized thin (~5 µm) elastomeric meshes consisting of aligned 1.7 µm diameter poly (ester-urethane urea) microfibers as substrates to examine their effect on hCSC viability, morphology, proliferation, and differentiation relative to cells cultured on tissue culture polystyrene (TCPS). The results showed that cells on microfiber meshes displayed an elongated morphology aligned in the direction of fiber orientation, lower proliferation rates, but increasedmore » expressions of genes and proteins majorly associated with cardiomyocyte phenotype. The early (NK2 homeobox 5, Nkx2.5) and late (cardiac troponin I, cTnI) cardiomyocyte genes were significantly increased on meshes (Nkx=2.5 56.2±13.0, cTnl=2.9±0.56,) over TCPS (Nkx2.5=4.2±0.9, cTnl=1.6±0.5, n=9, p<0.05 for both groups) after differentiation. In contrast, expressions of smooth muscle markers, Gata6 and myosin heavy chain (SM-MHC), were decreased on meshes. Immunocytochemical analysis with cardiac antibody exhibited the similar pattern of above cardiac differentiation. We conclude that aligned microfiber meshes are suitable for guiding cardiac differentiation of hCSCs and may facilitate stem cell-based therapies for treatment of cardiac diseases. - Highlights: • First study to characterize c-kit{sup +} human cardiac stem cells on microfiber meshes. • Microfiber meshes seem reducing cell proliferation, but no effect on cell viability. • Microfiber meshes facilitate the elongation of human cardiac stem cells in culture. • Cardiac but not smooth muscle differentiation were enhanced on microfiber meshes. • Microfiber meshes may be used as cardiac patches in cell-based cardiac therapy.« less

Comparison of a lightweight polypropylene mesh (Optilene® LP) and a large-pore knitted PTFE mesh (GORE® INFINIT® mesh)--Biocompatibility in a standardized endoscopic extraperitoneal hernia model.

PubMed

Jacob, Dietmar A; Schug-Pass, Christine; Sommerer, Florian; Tannapfel, Andrea; Lippert, Hans; Köckerling, Ferdinand

2012-02-01

The use of a mesh with good biocompatibility properties is of decisive importance for the avoidance of recurrences and chronic pain in endoscopic hernia repair surgery. As we know from numerous experiments and clinical experience, large-pore, lightweight polypropylene meshes possess the best biocompatibility. However, large-pore meshes of different polymers may be used as well and might be an alternative solution. Utilizing a totally extraperitoneal technique in an established animal model, 20 domestic pigs were implanted with either a lightweight large-pore polypropylene (PP) mesh (Optilene® LP) or a medium-weight large-pore knitted polytetrafluorethylene (PTFE) mesh (GORE® INFINIT® mesh). After 94 days, the pigs were sacrificed and postmortem diagnostic laparoscopy was performed, followed by explantation of the specimens for macroscopic, histological and immunohistochemical evaluation. The mean mesh shrinkage rate was 14.2% for Optilene® LP vs. 24.7% for INFINIT® mesh (p = 0.017). The partial volume of the inflammatory cells was 11.2% for Optilene® LP vs. 13.9% for INFINIT (n.s.). CD68 was significantly higher for INFINIT (11.8% vs. 5.6%, p = 0.007). The markers of cell turnover, namely Ki67 and the apoptotic index, were comparable at 6.4% vs. 12.4% (n.s.) and 1.6% vs. 2.0% (n.s.). In the extracellular matrix, TGF-β was 35.4% for Optilene® LP and 31.0% for INFINIT® (n.s.). Collagen I (pos/300 μm) deposits were 117.8 and 114.9, respectively. In our experimental examinations, Optilene® LP and INFINIT® showed a comparable biocompatibility in terms of chronic inflammatory reaction; however, the shrinkage rate was significantly higher for INFINIT® after 3 months. The higher shrinkage rate of INFINIT® should be taken into account when choosing the mesh size for an adequate hernia overlap.

Mechanical behavior of surgical meshes for abdominal wall repair: In vivo versus biaxial characterization.

PubMed

Simón-Allué, R; Ortillés, A; Calvo, B

2018-06-01

Despite the widespread use of synthetic meshes in the surgical treatment of the hernia pathology, the election criteria of a suitable mesh for specific patient continues to be uncertain. Thus, in this work, we propose a methodology to determine in advance potential disadvantages on the use of certain meshes based on the patient-specific abdominal geometry and the mechanical features of the certain meshes. To that purpose, we have first characterized the mechanical behavior of four synthetic meshes through biaxial tests. Secondly, two of these meshes were implanted in several New Zealand rabbits with a total defect previously created on the center of the abdominal wall. After the surgical procedure, specimen were subjected to in vivo pneumoperitoneum tests to determine the immediate post-surgical response of those meshes after implanted in a healthy specimen. Experimental performance was recorded by a stereo rig with the aim of obtaining quantitative information about the pressure-displacement relation of the abdominal wall. Finally, following the procedure presented in prior works (Simón-Allué et al., 2015, 2017), a finite element model was reconstructed from the experimental measurements and tests were computationally reproduced for the healthy and herniated cases. Simulations were compared and validated with the in vivo behavior and results were given along the abdominal wall in terms of displacements, stresses and strain. Mechanical characterization of the meshes revealed Surgipro TM as the most rigid implant and Neomesh SuperSoft® as the softer, while other two meshes (Neomesh Soft®, Neopore®) remained in between. These two meshes were employed in the experimental study and resulted in similar effect in the abdominal wall cavity and both were close to the healthy case. Simulations confirmed this result while showed potential objections in the case of the other two meshes, due to high values in stresses or elongation that may led to discomfort in real tissue. The use of this methodology on human surgery may provide the surgeons with reliable and useful information to avoid certain meshes on specific-patient treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of mesh style and grid convergence on particle deposition in bifurcating airway models with comparisons to experimental data.

PubMed

Longest, P Worth; Vinchurkar, Samir

2007-04-01

A number of research studies have employed a wide variety of mesh styles and levels of grid convergence to assess velocity fields and particle deposition patterns in models of branching biological systems. Generating structured meshes based on hexahedral elements requires significant time and effort; however, these meshes are often associated with high quality solutions. Unstructured meshes that employ tetrahedral elements can be constructed much faster but may increase levels of numerical diffusion, especially in tubular flow systems with a primary flow direction. The objective of this study is to better establish the effects of mesh generation techniques and grid convergence on velocity fields and particle deposition patterns in bifurcating respiratory models. In order to achieve this objective, four widely used mesh styles including structured hexahedral, unstructured tetrahedral, flow adaptive tetrahedral, and hybrid grids have been considered for two respiratory airway configurations. Initial particle conditions tested are based on the inlet velocity profile or the local inlet mass flow rate. Accuracy of the simulations has been assessed by comparisons to experimental in vitro data available in the literature for the steady-state velocity field in a single bifurcation model as well as the local particle deposition fraction in a double bifurcation model. Quantitative grid convergence was assessed based on a grid convergence index (GCI), which accounts for the degree of grid refinement. The hexahedral mesh was observed to have GCI values that were an order of magnitude below the unstructured tetrahedral mesh values for all resolutions considered. Moreover, the hexahedral mesh style provided GCI values of approximately 1% and reduced run times by a factor of 3. Based on comparisons to empirical data, it was shown that inlet particle seedings should be consistent with the local inlet mass flow rate. Furthermore, the mesh style was found to have an observable effect on cumulative particle depositions with the hexahedral solution most closely matching empirical results. Future studies are needed to assess other mesh generation options including various forms of the hybrid configuration and unstructured hexahedral meshes.

Impact experiments into multiple-mesh targets: Concept development of a lightweight collisional bumper

NASA Technical Reports Server (NTRS)

Hoerz, Friedrich; Cintala, Mark J.; Bernhard, Ronald P.; Cardenas, Frank; Davidson, William; Haynes, Gerald; See, Thomas H.; Winkler, Jerry; Gray, Barry

1993-01-01

The utility of multiple-mesh targets as potential lightweight shields to protect spacecraft in low-Earth orbit against collisional damage is explored. Earlier studies revealed that single meshes comminute hypervelocity impactors with efficiencies comparable to contiguous targets. Multiple interaction of projectile fragments with any number of meshes should lead to increased comminution, deceleration, and dispersion of the projectile, such that all debris exiting the mesh stack possesses low specific energies (ergs/sq cm) that would readily be tolerated by many flight systems. The study is conceptually exploring the sensitivity of major variables such as impact velocity, the specific areal mass (g/sq cm) of the total mesh stack (SM), and the separation distance (S) between individual meshes. Most experiments employed five or ten meshes with total SM typically less than 0.5 the specific mass of the impactor, and silicate glass impactors rather than metal projectiles. While projectile comminution increases with increasing impact velocity due to progressively higher shock stresses, encounters with multiple-meshes at low velocity (1-2 km/s) already lead to significant disruption of the glass impactors, with the resulting fragments being additionally decelerated and dispersed by subsequent meshes, and, unlike most contiguous single-plate bumpers, leading to respectable performance at low velocity. Total specific bumper mass must be the subject of careful trade-off studies; relatively massive bumpers will generate too much debris being dislodged from the bumper itself, while exceptionally lightweight designs will not cause sufficient comminution, deceleration, or dispersion of the impactor. Separation distance was found to be a crucial design parameter, as it controls the dispersion of the fragment cloud. Substantial mass savings could result if maximum separation distances were employed. The total mass of debris dislodged by multiple-mesh stacks is modestly smaller than that of single, contiguous-membrane shields. The cumulative surface area of all penetration holes in multiple mesh stacks is an order of magnitude smaller than that in analog multiple-foil shields, suggesting good long-term performance of the mesh designs. Due to different experimental conditions, direct and quantitative comparison with other lightweight shields is not possible at present.

Parallel three-dimensional magnetotelluric inversion using adaptive finite-element method. Part I: theory and synthetic study

NASA Astrophysics Data System (ADS)

Grayver, Alexander V.

2015-07-01

This paper presents a distributed magnetotelluric inversion scheme based on adaptive finite-element method (FEM). The key novel aspect of the introduced algorithm is the use of automatic mesh refinement techniques for both forward and inverse modelling. These techniques alleviate tedious and subjective procedure of choosing a suitable model parametrization. To avoid overparametrization, meshes for forward and inverse problems were decoupled. For calculation of accurate electromagnetic (EM) responses, automatic mesh refinement algorithm based on a goal-oriented error estimator has been adopted. For further efficiency gain, EM fields for each frequency were calculated using independent meshes in order to account for substantially different spatial behaviour of the fields over a wide range of frequencies. An automatic approach for efficient initial mesh design in inverse problems based on linearized model resolution matrix was developed. To make this algorithm suitable for large-scale problems, it was proposed to use a low-rank approximation of the linearized model resolution matrix. In order to fill a gap between initial and true model complexities and resolve emerging 3-D structures better, an algorithm for adaptive inverse mesh refinement was derived. Within this algorithm, spatial variations of the imaged parameter are calculated and mesh is refined in the neighborhoods of points with the largest variations. A series of numerical tests were performed to demonstrate the utility of the presented algorithms. Adaptive mesh refinement based on the model resolution estimates provides an efficient tool to derive initial meshes which account for arbitrary survey layouts, data types, frequency content and measurement uncertainties. Furthermore, the algorithm is capable to deliver meshes suitable to resolve features on multiple scales while keeping number of unknowns low. However, such meshes exhibit dependency on an initial model guess. Additionally, it is demonstrated that the adaptive mesh refinement can be particularly efficient in resolving complex shapes. The implemented inversion scheme was able to resolve a hemisphere object with sufficient resolution starting from a coarse discretization and refining mesh adaptively in a fully automatic process. The code is able to harness the computational power of modern distributed platforms and is shown to work with models consisting of millions of degrees of freedom. Significant computational savings were achieved by using locally refined decoupled meshes.

Ensemble methods with simple features for document zone classification

NASA Astrophysics Data System (ADS)

Obafemi-Ajayi, Tayo; Agam, Gady; Xie, Bingqing

2012-01-01

Document layout analysis is of fundamental importance for document image understanding and information retrieval. It requires the identification of blocks extracted from a document image via features extraction and block classification. In this paper, we focus on the classification of the extracted blocks into five classes: text (machine printed), handwriting, graphics, images, and noise. We propose a new set of features for efficient classifications of these blocks. We present a comparative evaluation of three ensemble based classification algorithms (boosting, bagging, and combined model trees) in addition to other known learning algorithms. Experimental results are demonstrated for a set of 36503 zones extracted from 416 document images which were randomly selected from the tobacco legacy document collection. The results obtained verify the robustness and effectiveness of the proposed set of features in comparison to the commonly used Ocropus recognition features. When used in conjunction with the Ocropus feature set, we further improve the performance of the block classification system to obtain a classification accuracy of 99.21%.

An Analysis of the Feasibility and Applicability of IEEE 802.x Wireless Mesh Networks within the Global Information Grid

DTIC Science & Technology

2004-09-01

MESH VS . SIMPLE AD HOC AND MANET..............................................5 B. DESIRABLE CHARACTERISTICS OF WIRELESS MESH NETWORKS...Comparison of Mesh (top) vs . Traditional Wireless (bottom) .............26 Figure 7. UML Model of SensorML Components (From SenorML Models Paper) ......30...50 Figure 17. Latency Difference Example – OLSR vs . AODV

Reconfigurable lattice mesh designs for programmable photonic processors.

PubMed

Pérez, Daniel; Gasulla, Ivana; Capmany, José; Soref, Richard A

2016-05-30

We propose and analyse two novel mesh design geometries for the implementation of tunable optical cores in programmable photonic processors. These geometries are the hexagonal and the triangular lattice. They are compared here to a previously proposed square mesh topology in terms of a series of figures of merit that account for metrics that are relevant to on-chip integration of the mesh. We find that that the hexagonal mesh is the most suitable option of the three considered for the implementation of the reconfigurable optical core in the programmable processor.

Method of generating a surface mesh

DOEpatents

Shepherd, Jason F [Albuquerque, NM; Benzley, Steven [Provo, UT; Grover, Benjamin T [Tracy, CA

2008-03-04

A method and machine-readable medium provide a technique to generate and modify a quadrilateral finite element surface mesh using dual creation and modification. After generating a dual of a surface (mesh), a predetermined algorithm may be followed to generate and modify a surface mesh of quadrilateral elements. The predetermined algorithm may include the steps of generating two-dimensional cell regions in dual space, determining existing nodes in primal space, generating new nodes in the dual space, and connecting nodes to form the quadrilateral elements (faces) for the generated and modifiable surface mesh.

Modeling Radiation Effects on a Triple Junction Solar Cell using Silvaco ATLAS

DTIC Science & Technology

2012-06-01

circuit voltage can then be calculated from ln 1 Loc t S IV V I        (4.3) where IS is the reverse saturation current, and Vt is the...orbiting electronic equipment. The first orbit of interest is the low Earth orbit ( LEO ). LEO encompasses any orbit within 650 kilometers of the...Light Beams #Solving #Meshing mesh width=200000 #X-Mesh: Surface=500 um2 = 1/200000 cm2 x.mesh loc =-250 spac=50 x.mesh loc =0 spac=10

[The use of a prolene double mesh for orbital wall reconstruction].

PubMed

Junceda-Moreno, J; Suárez-Suárez, E; Dos-Santos-Bernardo, V

2005-08-01

Patient with a recurrent carcinoma of the nasal fossae affecting the internal orbital wall. The intraorbital content was not affected. The orbital wall was reconstructed with a prolene double mesh anchored to the periosteum. Prolene mesh as a substitute of the orbital wall. Good stability and isolation of the intraorbital structures were observed. Ocular motility was completely normal after surgery without prolene mesh displacements. The prolene double mesh is a good surgical option to replace missing bone in the reconstruction of the internal orbital wall.

Synthetic mesh in the surgical repair of pelvic organ prolapse: current status and future directions.

PubMed

Keys, Tristan; Campeau, Lysanne; Badlani, Gopal

2012-08-01

In light of the recent Food and Drug Administration public health notification regarding complications associated with transvaginally placed mesh for pelvic organ prolapse (POP) repair, we review recent literature to evaluate current outcomes and complication data, analyze the clinical need for mesh on the basis of genetic and biochemical etiologies of POP, and investigate trends of mesh use via an American Urological Association member survey. Mesh-based techniques show better anatomic results than traditional repair of anterior POP, but subjective outcomes are equivalent. Further research and Level I evidence are required before mesh-based repair of POP can be standardized. Adequate surgical training and patient selection should decrease complication rates. Published by Elsevier Inc.

The numerical simulation study of hemodynamics of the new dense-mesh stent

NASA Astrophysics Data System (ADS)

Ma, Jiali; Yuan, Zhishan; Yu, Xuebao; Feng, Zhaowei; Miao, Weidong; Xu, Xueli; Li, Juntao

2017-09-01

The treatment of aortic aneurysm in new dense mesh stent is based on the principle of hemodynamic changes. But the mechanism is not yet very clear. This paper analyzed and calculated the hemodynamic situation before and after the new dense mesh stent implanting by the method of numerical simulation. The results show the dense mesh stent changed and impacted the blood flow in the aortic aneurysm. The changes include significant decrement of blood velocity, pressure and shear forces, while ensuring blood can supply branches, which means the new dense mesh stent's hemodynamic mechanism in the treatment of aortic aneurysm is clearer. It has very important significance in developing new dense mesh stent in order to cure aortic aneurysm.

Discrete Data Transfer Technique for Fluid-Structure Interaction

NASA Technical Reports Server (NTRS)

Samareh, Jamshid A.

2007-01-01

This paper presents a general three-dimensional algorithm for data transfer between dissimilar meshes. The algorithm is suitable for applications of fluid-structure interaction and other high-fidelity multidisciplinary analysis and optimization. Because the algorithm is independent of the mesh topology, we can treat structured and unstructured meshes in the same manner. The algorithm is fast and accurate for transfer of scalar or vector fields between dissimilar surface meshes. The algorithm is also applicable for the integration of a scalar field (e.g., coefficients of pressure) on one mesh and injection of the resulting vectors (e.g., force vectors) onto another mesh. The author has implemented the algorithm in a C++ computer code. This paper contains a complete formulation of the algorithm with a few selected results.

Biomedical literature classification using encyclopedic knowledge: a Wikipedia-based bag-of-concepts approach

PubMed Central

Pérez Rodríguez, Roberto; Anido Rifón, Luis E.

2015-01-01

Automatic classification of text documents into a set of categories has a lot of applications. Among those applications, the automatic classification of biomedical literature stands out as an important application for automatic document classification strategies. Biomedical staff and researchers have to deal with a lot of literature in their daily activities, so it would be useful a system that allows for accessing to documents of interest in a simple and effective way; thus, it is necessary that these documents are sorted based on some criteria—that is to say, they have to be classified. Documents to classify are usually represented following the bag-of-words (BoW) paradigm. Features are words in the text—thus suffering from synonymy and polysemy—and their weights are just based on their frequency of occurrence. This paper presents an empirical study of the efficiency of a classifier that leverages encyclopedic background knowledge—concretely Wikipedia—in order to create bag-of-concepts (BoC) representations of documents, understanding concept as “unit of meaning”, and thus tackling synonymy and polysemy. Besides, the weighting of concepts is based on their semantic relevance in the text. For the evaluation of the proposal, empirical experiments have been conducted with one of the commonly used corpora for evaluating classification and retrieval of biomedical information, OHSUMED, and also with a purpose-built corpus of MEDLINE biomedical abstracts, UVigoMED. Results obtained show that the Wikipedia-based bag-of-concepts representation outperforms the classical bag-of-words representation up to 157% in the single-label classification problem and up to 100% in the multi-label problem for OHSUMED corpus, and up to 122% in the single-label classification problem and up to 155% in the multi-label problem for UVigoMED corpus. PMID:26468436

An evaluation of computer assisted clinical classification algorithms.

PubMed

Chute, C G; Yang, Y; Buntrock, J

1994-01-01

The Mayo Clinic has a long tradition of indexing patient records in high resolution and volume. Several algorithms have been developed which promise to help human coders in the classification process. We evaluate variations on code browsers and free text indexing systems with respect to their speed and error rates in our production environment. The more sophisticated indexing systems save measurable time in the coding process, but suffer from incompleteness which requires a back-up system or human verification. Expert Network does the best job of rank ordering clinical text, potentially enabling the creation of thresholds for the pass through of computer coded data without human review.

Terminology extraction from medical texts in Polish

PubMed Central

2014-01-01

Background Hospital documents contain free text describing the most important facts relating to patients and their illnesses. These documents are written in specific language containing medical terminology related to hospital treatment. Their automatic processing can help in verifying the consistency of hospital documentation and obtaining statistical data. To perform this task we need information on the phrases we are looking for. At the moment, clinical Polish resources are sparse. The existing terminologies, such as Polish Medical Subject Headings (MeSH), do not provide sufficient coverage for clinical tasks. It would be helpful therefore if it were possible to automatically prepare, on the basis of a data sample, an initial set of terms which, after manual verification, could be used for the purpose of information extraction. Results Using a combination of linguistic and statistical methods for processing over 1200 children hospital discharge records, we obtained a list of single and multiword terms used in hospital discharge documents written in Polish. The phrases are ordered according to their presumed importance in domain texts measured by the frequency of use of a phrase and the variety of its contexts. The evaluation showed that the automatically identified phrases cover about 84% of terms in domain texts. At the top of the ranked list, only 4% out of 400 terms were incorrect while out of the final 200, 20% of expressions were either not domain related or syntactically incorrect. We also observed that 70% of the obtained terms are not included in the Polish MeSH. Conclusions Automatic terminology extraction can give results which are of a quality high enough to be taken as a starting point for building domain related terminological dictionaries or ontologies. This approach can be useful for preparing terminological resources for very specific subdomains for which no relevant terminologies already exist. The evaluation performed showed that none of the tested ranking procedures were able to filter out all improperly constructed noun phrases from the top of the list. Careful choice of noun phrases is crucial to the usefulness of the created terminological resource in applications such as lexicon construction or acquisition of semantic relations from texts. PMID:24976943