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Sample records for neural structures pedicle

  1. Anatomical study of lumbar vertebral pedicle and adjacent neural structures

    Directory of Open Access Journals (Sweden)

    Matuoka Cláudia Maria

    2002-01-01

    Full Text Available For the evaluation of the Lumbar pedicle morphometry and its relation to the neural structures, 14 male adult cadavers were dissected, and the size of the lumbar pedicle was assessed by measuring its sagittal and transversal diameter. It was found that the size of the pedicle increases from L2 to L5, both in the sagittal and transversal diameter, the first bigger. The relation of the lumbar pedicle to the neural structures was evaluated by measuring the distance between dura-mater and the pedicle medial area, the distance between the most distal area of the pedicle and the nerve root that appears under it, and , to obtain in an indirect way, the distance between the pedicle apex and the nerve root that appears over it. The acquired results showed that the distance between the most distal area of the pedicle and the nerve root that appears under it, and the distance between the pedicle medial area and dura-mater, do not increase from L2 to L5, and they are in average 1,98 and 3,02 respectively. The distance between the pedicle apex and the nerve root that appears over it, increases from L2 to L5, varying from 13,64 in L2 to 21,62 in L5. The location of the spinal ganglion in relation to the pedicle has also been found, and 87% of the spinal ganglions are located in the foraminal zone.

  2. Multiobjective Optimization Design of Spinal Pedicle Screws Using Neural Networks and Genetic Algorithm: Mathematical Models and Mechanical Validation

    Directory of Open Access Journals (Sweden)

    Yongyut Amaritsakul

    2013-01-01

    Full Text Available Short-segment instrumentation for spine fractures is threatened by relatively high failure rates. Failure of the spinal pedicle screws including breakage and loosening may jeopardize the fixation integrity and lead to treatment failure. Two important design objectives, bending strength and pullout strength, may conflict with each other and warrant a multiobjective optimization study. In the present study using the three-dimensional finite element (FE analytical results based on an L25 orthogonal array, bending and pullout objective functions were developed by an artificial neural network (ANN algorithm, and the trade-off solutions known as Pareto optima were explored by a genetic algorithm (GA. The results showed that the knee solutions of the Pareto fronts with both high bending and pullout strength ranged from 92% to 94% of their maxima, respectively. In mechanical validation, the results of mathematical analyses were closely related to those of experimental tests with a correlation coefficient of −0.91 for bending and 0.93 for pullout (P<0.01 for both. The optimal design had significantly higher fatigue life (P<0.01 and comparable pullout strength as compared with commercial screws. Multiobjective optimization study of spinal pedicle screws using the hybrid of ANN and GA could achieve an ideal with high bending and pullout performances simultaneously.

  3. Multiobjective optimization design of spinal pedicle screws using neural networks and genetic algorithm: mathematical models and mechanical validation.

    Science.gov (United States)

    Amaritsakul, Yongyut; Chao, Ching-Kong; Lin, Jinn

    2013-01-01

    Short-segment instrumentation for spine fractures is threatened by relatively high failure rates. Failure of the spinal pedicle screws including breakage and loosening may jeopardize the fixation integrity and lead to treatment failure. Two important design objectives, bending strength and pullout strength, may conflict with each other and warrant a multiobjective optimization study. In the present study using the three-dimensional finite element (FE) analytical results based on an L25 orthogonal array, bending and pullout objective functions were developed by an artificial neural network (ANN) algorithm, and the trade-off solutions known as Pareto optima were explored by a genetic algorithm (GA). The results showed that the knee solutions of the Pareto fronts with both high bending and pullout strength ranged from 92% to 94% of their maxima, respectively. In mechanical validation, the results of mathematical analyses were closely related to those of experimental tests with a correlation coefficient of -0.91 for bending and 0.93 for pullout (P < 0.01 for both). The optimal design had significantly higher fatigue life (P < 0.01) and comparable pullout strength as compared with commercial screws. Multiobjective optimization study of spinal pedicle screws using the hybrid of ANN and GA could achieve an ideal with high bending and pullout performances simultaneously.

  4. Reactive sclerosis of the pedicle

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sun Wha; Lim, Jae Hoon [Kyung Hee University Hospital, Seoul (Korea, Republic of)

    1991-01-15

    The vertebral pedicles of the neural arch represent the 'eyes' through which normal variants, anomalies and acquired pathologic conditions can be detected on lumbar spine radiographs. Close scrutiny of the size, shape, density and margins of the pedicles may permit the radiologist to suggest a wide variety of disease. Radiologic attention is almost always directed at determining of sclerosis or lysis of the pedicle. Numerous conditions causing sclerosis of the pedicle have been reported and among them osteoidosteoma and osteoblastoma are well known tumors. However the real significance of reactive sclerosis of the pedicle related to the unstable neural arch such as contralateral spondyloysis have drawn little attention in the literature. The purpose of this report is to analyze the nature of arch deficiency which is the primary lesion related to the sclerotic pedicle, and emphasizes the significance of radiologic features of reactive pedicular sclerosis for clinical practice. Cautious observation of both sclerotic lesion and the contralateral neural arch is essential in radiologic evaluation of the scleortic pedicle and the presence of a contraslateral pars defect in the same vertebral segment suggests reactive sclerosis of the pedicle.

  5. Multi-scale finite element modelling at the posterior lumbar vertebra: analysis of pedicle stresses due to pars fracture.

    Science.gov (United States)

    Inceoğlu, Serkan; Mageswaran, Prasath

    2014-05-01

    Multi-scale finite element (FE) model is a cost-effective way to analyse stress response of micro-level structures to the changes in loading at macro-level. This study deals with the development of a multi-scale model of a human vertebra and stress changes in the pedicle at high resolution after a gross fracture at the posterior neural arch. Spondylolysis (pars fracture) is a painful condition occurring in the vertebral neural arch and common especially among the athletic young population. The fracture of the pars significantly alters load distribution and load transfer characteristics at the neural arch. Structural changes in the posterior vertebra due to the new loading patterns can trigger secondary complications. Clinical reports have shown the association of pedicle hypertrophy or pedicle fracture with unilateral pars fractures. However, the biomechanical consequences of pars fracture and its effect on the pedicle have never been studied in detail. Therefore, we prepared a multi-scale model of posterior vertebra with continuum laminar complex model combined with micro-FE model of a pedicle section. The results showed that stress at the contralateral pars and pedicle increased after unilateral pars fracture simulation. High-stress regions were found around the outer boundaries of the pedicle. This model and information are helpful in understanding the stress changes in the pedicle and can be used for adaptive remodelling studies.

  6. Management of fracture-dislocation of the lower cervical spine with the cervical pedicle screw system.

    Science.gov (United States)

    Zhou, Feng; Zou, Jun; Gan, Minfeng; Zhu, Ruofu; Yang, Huilin

    2010-07-01

    Usually, cervical pedicle screw fixation has been considered too risky for neurovascular structures. The purpose of this study was to investigate the method and efficacy of the cervical pedicle screw system for fracture-dislocation of the cervical spine because of its rigid fixation. A prospective study was conducted involving 48 patients with cervical spine fracture-dislocation who underwent cervical pedicle screw fixation surgery between January 2003 and January 2007. All patients had various degrees of cord injury, and they were classified according to the American Spinal Cord Injury Association (ASIA) Impairment Scale: 18 cases were grade A, 15 grade B, 10 grade C, and 5 grade D. Six months after the operation, all patients had achieved solid bony fusion and stable fixation of the related segments. Thirty patients with incomplete spinal cord injury improved their ASIA Impairment Scale classification by 1 to 2 grades after the operation. Eighteen patients with complete spinal cord injury had no improvement in neural function. However, nerve root symptoms such as pain and numbness were alleviated to some extent. The cervical pedicle screw system is an effective and reliable method for the restoration of cervical stability. Sufficient pre-operative imaging studies of the pedicles and strict screw insertion technique should be emphasised.

  7. Neural Networks for protein Structure Prediction

    DEFF Research Database (Denmark)

    Bohr, Henrik

    1998-01-01

    This is a review about neural network applications in bioinformatics. Especially the applications to protein structure prediction, e.g. prediction of secondary structures, prediction of surface structure, fold class recognition and prediction of the 3-dimensional structure of protein backbones...

  8. A Topological Perspective of Neural Network Structure

    Science.gov (United States)

    Sizemore, Ann; Giusti, Chad; Cieslak, Matthew; Grafton, Scott; Bassett, Danielle

    The wiring patterns of white matter tracts between brain regions inform functional capabilities of the neural network. Indeed, densely connected and cyclically arranged cognitive systems may communicate and thus perform distinctly. However, previously employed graph theoretical statistics are local in nature and thus insensitive to such global structure. Here we present an investigation of the structural neural network in eight healthy individuals using persistent homology. An extension of homology to weighted networks, persistent homology records both circuits and cliques (all-to-all connected subgraphs) through a repetitive thresholding process, thus perceiving structural motifs. We report structural features found across patients and discuss brain regions responsible for these patterns, finally considering the implications of such motifs in relation to cognitive function.

  9. Neural Correlates of Verb Argument Structure Processing

    OpenAIRE

    Thompson, Cynthia K.; Bonakdarpour, Borna; Fix, Stephen C.; Blumenfeld, Henrike K.; Parrish, Todd B.; Gitelman, Darren R.; Mesulam, M.-Marsel

    2007-01-01

    Neuroimaging and lesion studies suggest that processing of word classes, such as verbs and nouns, is associated with distinct neural mechanisms. Such studies also suggest that subcategories within these broad word class categories are differentially processed in the brain. Within the class of verbs, argument structure provides one linguistic dimension that distinguishes among verb exemplars, with some requiring more complex argument structure entries than others. This study examined the neura...

  10. Neural correlates of verb argument structure processing.

    Science.gov (United States)

    Thompson, Cynthia K; Bonakdarpour, Borna; Fix, Stephen C; Blumenfeld, Henrike K; Parrish, Todd B; Gitelman, Darren R; Mesulam, M-Marsel

    2007-11-01

    Neuroimaging and lesion studies suggest that processing of word classes, such as verbs and nouns, is associated with distinct neural mechanisms. Such studies also suggest that subcategories within these broad word class categories are differentially processed in the brain. Within the class of verbs, argument structure provides one linguistic dimension that distinguishes among verb exemplars, with some requiring more complex argument structure entries than others. This study examined the neural instantiation of verbs by argument structure complexity: one-, two-, and three-argument verbs. Stimuli of each type, along with nouns and pseudowords, were presented for lexical decision using an event-related functional magnetic resonance imaging design. Results for 14 young normal participants indicated largely overlapping activation maps for verbs and nouns, with no areas of significant activation for verbs compared to nouns, or vice versa. Pseudowords also engaged neural tissue overlapping with that for both word classes, with more widespread activation noted in visual, motor, and peri-sylvian regions. Examination of verbs by argument structure revealed activation of the supramarginal and angular gyri, limited to the left hemisphere only when verbs with two obligatory arguments were compared to verbs with a single argument. However, bilateral activation was noted when both two- and three-argument verbs were compared to one-argument verbs. These findings suggest that posterior peri-sylvian regions are engaged for processing argument structure information associated with verbs, with increasing neural tissue in the inferior parietal region associated with increasing argument structure complexity. These findings are consistent with processing accounts, which suggest that these regions are crucial for semantic integration.

  11. Hierarchical Neural Network Structures for Phoneme Recognition

    CERN Document Server

    Vasquez, Daniel; Minker, Wolfgang

    2013-01-01

    In this book, hierarchical structures based on neural networks are investigated for automatic speech recognition. These structures are evaluated on the phoneme recognition task where a  Hybrid Hidden Markov Model/Artificial Neural Network paradigm is used. The baseline hierarchical scheme consists of two levels each which is based on a Multilayered Perceptron. Additionally, the output of the first level serves as a second level input. The computational speed of the phoneme recognizer can be substantially increased by removing redundant information still contained at the first level output. Several techniques based on temporal and phonetic criteria have been investigated to remove this redundant information. The computational time could be reduced by 57% whilst keeping the system accuracy comparable to the baseline hierarchical approach.

  12. Pedicled perforator flaps

    DEFF Research Database (Denmark)

    Demirtas, Yener; Ozturk, Nuray; Kelahmetoglu, Osman

    2009-01-01

    adequately to cover the defect. Defects measuring 3 x 3 cm up to 20 x 20 cm at diverse locations were successfully reconstructed in 20 of 21 patients with 26 flaps. Pedicled perforator flaps offer us reliable and satisfactory results of reconstruction at different anatomic territories of the body. It sounds...

  13. Effect of different inner core diameters on structural strength of cannulated pedicle screws under various lumbar spine movements.

    Science.gov (United States)

    Chang, Chia-Ming; Lai, Yu-Shu; Cheng, Cheng-Kung

    2017-08-15

    Currently, cannulated pedicle screws have been widely used in minimal invasive or navigation techniques. However, the stress distribution and the strength of different core diameters of cannulated screw are not clear. This study aimed to investigate the mechanical strength of cannulated screws with different inner core diameter under various lumbar spine movements using finite element analysis. The results showed that the von-Mises stress of a cannulated screw was larger than that of a solid screw in all loading conditions, especially above 2 mm in cannulated core diameter. In lateral bending, extension, and flexion, the maximum von-Mises stress was found approximate to the proximal thread for all types of screws. In rotation condition, the maximum von-Mises stress was located at the middle of the screw. Additionally, the difference in stiffness of instrumented levels was not significant among four screws under the same loading condition. Cannulated screws could provide enough stability for the vertebral body fusion comparing to solid screws. The diameter of cannulated core is suggested not to exceed 2.0 mm.

  14. Identification of Non-Linear Structures using Recurrent Neural Networks

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Nielsen, Søren R. K.; Hansen, H. I.

    1995-01-01

    Two different partially recurrent neural networks structured as Multi Layer Perceptrons (MLP) are investigated for time domain identification of a non-linear structure.......Two different partially recurrent neural networks structured as Multi Layer Perceptrons (MLP) are investigated for time domain identification of a non-linear structure....

  15. Identification of Non-Linear Structures using Recurrent Neural Networks

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Nielsen, Søren R. K.; Hansen, H. I.

    Two different partially recurrent neural networks structured as Multi Layer Perceptrons (MLP) are investigated for time domain identification of a non-linear structure.......Two different partially recurrent neural networks structured as Multi Layer Perceptrons (MLP) are investigated for time domain identification of a non-linear structure....

  16. Radilogic evaluation of pedicle lumbar and spinal canal dimensions in north-west of Iran using computed tomography

    Directory of Open Access Journals (Sweden)

    Lotfinia I

    2010-05-01

    Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Pedicular screws are currently the gold standard of internal fixation of spinal column. Pedicular screws have their own complications, however the surgeon should be aware of morphometery of pedicles, as well as the anatomy of surrounding neural structures to minimize these risks. No national study has ever examined the physical characteristics of lumbar pedicles and this study is unique for this purpose."n"nMethods: This study covers the patients undergoing lumbar spinal CT-scanning due to variable causes. 25 vertebrae were selected in either gender, 18 years or older and E-Film computer software was employed to measure different diameters of pedicle and the results were analyzed with p≤0.05 regarded as significant."n"nResults: L5 pedicle was the widest (16.8 mm, while L1 was the narrowest (8.25 mm. this figure was 8.82, 10.48 and 12.86 mm for L2, L3, L4 respectively. Longitudinal depth of pedicle was 47.98, 48.68, 50.42, 48.32 and 47.8 mm for L1, L2, L3, L4, L5 respectively. Statistically significant differences were found between some dimensions detected in our study and similar studies."n"nConclusions: The advantages of pedicular screws and rods to stabilize spinal column are well known. To avoid

  17. Aspects of randomness in neural graph structures

    CERN Document Server

    Rudolph-Lilith, Michelle

    2013-01-01

    In the past two decades, significant advances have been made in understanding the structural and functional properties of biological networks, via graph-theoretic analysis. In general, most graph-theoretic studies are conducted in the presence of serious uncertainties, such as major undersampling of the experimental data. In the specific case of neural systems, however, a few moderately robust experimental reconstructions do exist, and these have long served as fundamental prototypes for studying connectivity patterns in the nervous system. In this paper, we provide a comparative analysis of these "historical" graphs, both in (unmodified) directed and (often symmetrized) undirected forms, and focus on simple structural characterizations of their connectivity. We find that in most measures the networks studied are captured by simple random graph models; in a few key measures, however, we observe a marked departure from the random graph prediction. Our results suggest that the mechanism of graph formation in th...

  18. Therapeutic efficacy of pedicle screw-rod internal fixation after one-stage posterior transforaminal lesion debridement and non-structural bone grafting for tuberculosis of lumbar vertebra

    Directory of Open Access Journals (Sweden)

    Jia-ming LIU

    2015-11-01

    Full Text Available Objective To evaluate the efficacy and safety of pedicle screw-rod internal fixation after one-stage posterior transforaminal lesion debridement and non-structural bone grafting in the treatment of tuberculosis of mono-segmental lumbar vertebra. Methods From January 2010 to April 2013, 21 patients (9 males and 12 females with an average age of 49.1 years with mono-segmental tuberculosis of lumbar vertebra underwent surgery in our hospital were included. Eight patients had neurological deficit. The focus of tuberculosis was located on one side of the vertebral body, and all the patients had obvious signs of bone destruction on CT and MRI. All the patients were given anti-tuberculosis chemotherapy for 2-3 weeks before surgery. The local bone chips and autologous iliac cancellous bone were used as the intervertebral bone graft. Postoperative plain radiographs and CT were obtained to evaluate the fusion rate and degree of lumbar lordosis. The visual analogue scale score (VAS, erythrocyte sedimentation rate (ESR, and C-reactive protein (CRP before and after operation, and at final follow-up date were recorded. Results All the patients were followed up for 25.3±4.2 months. The mean operation time was 157±39 minutes, and the average blood loss was 470±143ml. The fusion rate of the interbody bone graft was 95.2%, with an average fusion period of 6.1±2.5 months. The neurological function was improved by 100%, and no severe complication or neurological injury occured. The preoperative and postoperative lordosis angles of the lumbar spine were 21.4°±5.7° and 33.6°±3.1°, respectively, and it was 31.3°±2.7° at the final follow up. The preoperative and postoperative VAS scores were 7.8±2.6 and 2.4±1.7 respectively, and it was 0.9±0.7 at the final follow up. The ESR and CRP were significantly decreased 3 months after surgery, and they became normal at 6 months. Conclusion Pedicle screw-rod internal fixation after one-stage posterior

  19. The structural neural substrate of subjective happiness.

    Science.gov (United States)

    Sato, Wataru; Kochiyama, Takanori; Uono, Shota; Kubota, Yasutaka; Sawada, Reiko; Yoshimura, Sayaka; Toichi, Motomi

    2015-11-20

    Happiness is a subjective experience that is an ultimate goal for humans. Psychological studies have shown that subjective happiness can be measured reliably and consists of emotional and cognitive components. However, the neural substrates of subjective happiness remain unclear. To investigate this issue, we used structural magnetic resonance imaging and questionnaires that assessed subjective happiness, the intensity of positive and negative emotional experiences, and purpose in life. We found a positive relationship between the subjective happiness score and gray matter volume in the right precuneus. Moreover, the same region showed an association with the combined positive and negative emotional intensity and purpose in life scores. Our findings suggest that the precuneus mediates subjective happiness by integrating the emotional and cognitive components of happiness.

  20. The structural neural substrate of subjective happiness

    Science.gov (United States)

    Sato, Wataru; Kochiyama, Takanori; Uono, Shota; Kubota, Yasutaka; Sawada, Reiko; Yoshimura, Sayaka; Toichi, Motomi

    2015-01-01

    Happiness is a subjective experience that is an ultimate goal for humans. Psychological studies have shown that subjective happiness can be measured reliably and consists of emotional and cognitive components. However, the neural substrates of subjective happiness remain unclear. To investigate this issue, we used structural magnetic resonance imaging and questionnaires that assessed subjective happiness, the intensity of positive and negative emotional experiences, and purpose in life. We found a positive relationship between the subjective happiness score and gray matter volume in the right precuneus. Moreover, the same region showed an association with the combined positive and negative emotional intensity and purpose in life scores. Our findings suggest that the precuneus mediates subjective happiness by integrating the emotional and cognitive components of happiness. PMID:26586449

  1. Neural Schematics as a unified formal graphical representation of large-scale Neural Network Structures

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    Matthias eEhrlich

    2013-10-01

    Full Text Available One of the major outcomes of neuroscientific research are models of Neural Network Structures. Descriptions of these models usually consist of a non-standardized mixture of text, figures, and other means of visual information communication in print media. However, as neuroscience is an interdisciplinary domain by nature, a standardized way of consistently representing models of Neural Network Structures is required. While generic descriptions of such models in textual form have recently been developed, a formalized way of schematically expressing them does not exist to date. Hence, in this paper we present Neural Schematics as a concept inspired by similar approaches from other disciplines for a generic two dimensional representation of said structures. After introducing Neural Network Structures in general, a set of current visualizations of models of Neural Network Structures is reviewed and analyzed for what information they convey and how their elements are rendered. This analysis then allows for the definition of general items and symbols to consistently represent these models as Neural Schematics on a two dimensional plane. We will illustrate the possibilities an agreed upon standard can yield on sampled diagrams transformed into Neural Schematics and an example application for the design and modeling of large-scale Neural Network Structures.

  2. Automated Modeling of Microwave Structures by Enhanced Neural Networks

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    Z. Raida

    2006-12-01

    Full Text Available The paper describes the methodology of the automated creation of neural models of microwave structures. During the creation process, artificial neural networks are trained using the combination of the particle swarm optimization and the quasi-Newton method to avoid critical training problems of the conventional neural nets. In the paper, neural networks are used to approximate the behavior of a planar microwave filter (moment method, Zeland IE3D. In order to evaluate the efficiency of neural modeling, global optimizations are performed using numerical models and neural ones. Both approaches are compared from the viewpoint of CPU-time demands and the accuracy. Considering conclusions, methodological recommendations for including neural networks to the microwave design are formulated.

  3. Combining neural networks for protein secondary structure prediction

    DEFF Research Database (Denmark)

    Riis, Søren Kamaric

    1995-01-01

    In this paper structured neural networks are applied to the problem of predicting the secondary structure of proteins. A hierarchical approach is used where specialized neural networks are designed for each structural class and then combined using another neural network. The submodels are designed...... by using a priori knowledge of the mapping between protein building blocks and the secondary structure and by using weight sharing. Since none of the individual networks have more than 600 adjustable weights over-fitting is avoided. When ensembles of specialized experts are combined the performance...

  4. Modeling Broadband Microwave Structures by Artificial Neural Networks

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    V. Otevrel

    2004-06-01

    Full Text Available The paper describes the exploitation of feed-forward neural networksand recurrent neural networks for replacing full-wave numerical modelsof microwave structures in complex microwave design tools. Building aneural model, attention is turned to the modeling accuracy and to theefficiency of building a model. Dealing with the accuracy, we describea method of increasing it by successive completing a training set.Neural models are mutually compared in order to highlight theiradvantages and disadvantages. As a reference model for comparisons,approximations based on standard cubic splines are used. Neural modelsare used to replace both the time-domain numeric models and thefrequency-domain ones.

  5. Neural networks for harmonic structure in music perception and action

    OpenAIRE

    Bianco, R.; Novembre, G.; Keller, P. E.; Kim, S G; Scharf, F.; Friederici, A. D.; Villringer, A; Sammler, D.

    2016-01-01

    The ability to predict upcoming structured events based on long-term knowledge and contextual priors is a fundamental principle of human cognition. Tonal music triggers predictive processes based on structural properties of harmony, i.e., regularities defining the arrangement of chords into well-formed musical sequences. While the neural architecture of structure-based predictions during music perception is well described, little is known about the neural networks for analogous predictions in...

  6. Linking neural and symbolic representation and processing of conceptual structures

    NARCIS (Netherlands)

    van der Velde, Frank; Forth, Jamie; Nazareth, Deniece S.; Wiggins, Geraint A.

    2017-01-01

    We compare and discuss representations in two cognitive architectures aimed at representing and processing complex conceptual (sentence-like) structures. First is the Neural Blackboard Architecture (NBA), which aims to account for representation and processing of complex and combinatorial conceptual

  7. Neural Network Algorithm for Prediction of Secondary Protein Structure

    National Research Council Canada - National Science Library

    Zikrija Avdagic; Elvir Purisevic; Emir Buza; Zlatan Coralic

    2009-01-01

    .... In this paper we describe the method and results of using CB513 as a dataset suitable for development of artificial neural network algorithms for prediction of secondary protein structure with MATLAB...

  8. Neural network definitions of highly predictable protein secondary structure classes

    Energy Technology Data Exchange (ETDEWEB)

    Lapedes, A. [Los Alamos National Lab., NM (United States)]|[Santa Fe Inst., NM (United States); Steeg, E. [Toronto Univ., ON (Canada). Dept. of Computer Science; Farber, R. [Los Alamos National Lab., NM (United States)

    1994-02-01

    We use two co-evolving neural networks to determine new classes of protein secondary structure which are significantly more predictable from local amino sequence than the conventional secondary structure classification. Accurate prediction of the conventional secondary structure classes: alpha helix, beta strand, and coil, from primary sequence has long been an important problem in computational molecular biology. Neural networks have been a popular method to attempt to predict these conventional secondary structure classes. Accuracy has been disappointingly low. The algorithm presented here uses neural networks to similtaneously examine both sequence and structure data, and to evolve new classes of secondary structure that can be predicted from sequence with significantly higher accuracy than the conventional classes. These new classes have both similarities to, and differences with the conventional alpha helix, beta strand and coil.

  9. Linking Neural and Symbolic Representation and Processing of Conceptual Structures

    Directory of Open Access Journals (Sweden)

    Frank van der Velde

    2017-08-01

    Full Text Available We compare and discuss representations in two cognitive architectures aimed at representing and processing complex conceptual (sentence-like structures. First is the Neural Blackboard Architecture (NBA, which aims to account for representation and processing of complex and combinatorial conceptual structures in the brain. Second is IDyOT (Information Dynamics of Thinking, which derives sentence-like structures by learning statistical sequential regularities over a suitable corpus. Although IDyOT is designed at a level more abstract than the neural, so it is a model of cognitive function, rather than neural processing, there are strong similarities between the composite structures developed in IDyOT and the NBA. We hypothesize that these similarities form the basis of a combined architecture in which the individual strengths of each architecture are integrated. We outline and discuss the characteristics of this combined architecture, emphasizing the representation and processing of conceptual structures.

  10. Microscopic neural image registration based on the structure of mitochondria

    Science.gov (United States)

    Cao, Huiwen; Han, Hua; Rao, Qiang; Xiao, Chi; Chen, Xi

    2017-02-01

    Microscopic image registration is a key component of the neural structure reconstruction with serial sections of neural tissue. The goal of microscopic neural image registration is to recover the 3D continuity and geometrical properties of specimen. During image registration, various distortions need to be corrected, including image rotation, translation, tissue deformation et.al, which come from the procedure of sample cutting, staining and imaging. Furthermore, there is only certain similarity between adjacent sections, and the degree of similarity depends on local structure of the tissue and the thickness of the sections. These factors make the microscopic neural image registration a challenging problem. To tackle the difficulty of corresponding landmarks extraction, we introduce a novel image registration method for Scanning Electron Microscopy (SEM) images of serial neural tissue sections based on the structure of mitochondria. The ellipsoidal shape of mitochondria ensures that the same mitochondria has similar shape between adjacent sections, and its characteristic of broad distribution in the neural tissue guarantees that landmarks based on the mitochondria distributed widely in the image. The proposed image registration method contains three parts: landmarks extraction between adjacent sections, corresponding landmarks matching and image deformation based on the correspondences. We demonstrate the performance of our method with SEM images of drosophila brain.

  11. Neural entrainment to the rhythmic structure of music.

    Science.gov (United States)

    Tierney, Adam; Kraus, Nina

    2015-02-01

    The neural resonance theory of musical meter explains musical beat tracking as the result of entrainment of neural oscillations to the beat frequency and its higher harmonics. This theory has gained empirical support from experiments using simple, abstract stimuli. However, to date there has been no empirical evidence for a role of neural entrainment in the perception of the beat of ecologically valid music. Here we presented participants with a single pop song with a superimposed bassoon sound. This stimulus was either lined up with the beat of the music or shifted away from the beat by 25% of the average interbeat interval. Both conditions elicited a neural response at the beat frequency. However, although the on-the-beat condition elicited a clear response at the first harmonic of the beat, this frequency was absent in the neural response to the off-the-beat condition. These results support a role for neural entrainment in tracking the metrical structure of real music and show that neural meter tracking can be disrupted by the presentation of contradictory rhythmic cues.

  12. Neural-Fitted TD-Leaf Learning for Playing Othello With Structured Neural Networks

    NARCIS (Netherlands)

    van den Dries, Sjoerd; Wiering, Marco A.

    2012-01-01

    This paper describes a methodology for quickly learning to play games at a strong level. The methodology consists of a novel combination of three techniques, and a variety of experiments on the game of Othello demonstrates their usefulness. First, structures or topologies in neural network

  13. Community structure of complex networks based on continuous neural network

    Science.gov (United States)

    Dai, Ting-ting; Shan, Chang-ji; Dong, Yan-shou

    2017-09-01

    As a new subject, the research of complex networks has attracted the attention of researchers from different disciplines. Community structure is one of the key structures of complex networks, so it is a very important task to analyze the community structure of complex networks accurately. In this paper, we study the problem of extracting the community structure of complex networks, and propose a continuous neural network (CNN) algorithm. It is proved that for any given initial value, the continuous neural network algorithm converges to the eigenvector of the maximum eigenvalue of the network modularity matrix. Therefore, according to the stability of the evolution of the network symbol will be able to get two community structure.

  14. Combinatorial structures and processing in neural blackboard architectures

    NARCIS (Netherlands)

    van der Velde, Frank; van der Velde, Frank; de Kamps, Marc; Besold, Tarek R.; d'Avila Garcez, Artur; Marcus, Gary F.; Miikkulainen, Risto

    2015-01-01

    We discuss and illustrate Neural Blackboard Architectures (NBAs) as the basis for variable binding and combinatorial processing the brain. We focus on the NBA for sentence structure. NBAs are based on the notion that conceptual representations are in situ, hence cannot be copied or transported.

  15. Discriminative training of self-structuring hidden control neural models

    DEFF Research Database (Denmark)

    Sørensen, Helge Bjarup Dissing; Hartmann, Uwe; Hunnerup, Preben

    1995-01-01

    This paper presents a new training algorithm for self-structuring hidden control neural (SHC) models. The SHC models were trained non-discriminatively for speech recognition applications. Better recognition performance can generally be achieved, if discriminative training is applied instead. Thus...

  16. Product Cost Management Structures: a review and neural network modelling

    Directory of Open Access Journals (Sweden)

    P. Jha

    2003-11-01

    Full Text Available This paper reviews the growth of approaches in product costing and draws synergies with information management and resource planning systems, to investigate potential application of state of the art modelling techniques of neural networks. Increasing demands on costing systems to serve multiple decision-making objectives, have made it essential to use better techniques for analysis of available data. This need is highlighted in the paper. The approach of neural networks, which have several analogous facets to complement and aid the information demands of modern product costing, Enterprise Resource Planning (ERP structures and the dominant-computing environment (for information management in the object oriented paradigm form the domain for investigation. Simulated data is used in neural network applications across activities that consume resources and deliver products, to generate information for monitoring and control decisions. The results in application for feature extraction and variation detection and their implications are presented in the paper.

  17. Structured learning via convolutional neural networks for vehicle detection

    Science.gov (United States)

    Maqueda, Ana I.; del Blanco, Carlos R.; Jaureguizar, Fernando; García, Narciso

    2017-05-01

    One of the main tasks in a vision-based traffic monitoring system is the detection of vehicles. Recently, deep neural networks have been successfully applied to this end, outperforming previous approaches. However, most of these works generally rely on complex and high-computational region proposal networks. Others employ deep neural networks as a segmentation strategy to achieve a semantic representation of the object of interest, which has to be up-sampled later. In this paper, a new design for a convolutional neural network is applied to vehicle detection in highways for traffic monitoring. This network generates a spatially structured output that encodes the vehicle locations. Promising results have been obtained in the GRAM-RTM dataset.

  18. Structural and functional neural correlates of music perception.

    Science.gov (United States)

    Limb, Charles J

    2006-04-01

    This review article highlights state-of-the-art functional neuroimaging studies and demonstrates the novel use of music as a tool for the study of human auditory brain structure and function. Music is a unique auditory stimulus with properties that make it a compelling tool with which to study both human behavior and, more specifically, the neural elements involved in the processing of sound. Functional neuroimaging techniques represent a modern and powerful method of investigation into neural structure and functional correlates in the living organism. These methods have demonstrated a close relationship between the neural processing of music and language, both syntactically and semantically. Greater neural activity and increased volume of gray matter in Heschl's gyrus has been associated with musical aptitude. Activation of Broca's area, a region traditionally considered to subserve language, is important in interpreting whether a note is on or off key. The planum temporale shows asymmetries that are associated with the phenomenon of perfect pitch. Functional imaging studies have also demonstrated activation of primitive emotional centers such as ventral striatum, midbrain, amygdala, orbitofrontal cortex, and ventral medial prefrontal cortex in listeners of moving musical passages. In addition, studies of melody and rhythm perception have elucidated mechanisms of hemispheric specialization. These studies show the power of music and functional neuroimaging to provide singularly useful tools for the study of brain structure and function.

  19. Neural correlates of artificial syntactic structure classification.

    NARCIS (Netherlands)

    Forkstam, C.H.; Hagoort, P.; Fernandez, G.S.E.; Ingvar, M.; Petersson, K.M.

    2006-01-01

    The human brain supports acquisition mechanisms that extract structural regularities implicitly from experience without the induction of an explicit model. It has been argued that the capacity to generalize to new input is based on the acquisition of abstract representations, which reflect

  20. Neural correlates of artificial syntactic structure classification

    NARCIS (Netherlands)

    Forkstam, C.H.; Hagoort, P.; Fernandez, G.S.E.; Ingvar, M.; Petersson, K.M.

    2006-01-01

    The human brain supports acquisition mechanisms that extract structural regularities implicitly from experience without the induction of an explicit model. It has been argued that the capacity to generalize to new input is based on the acquisition of abstract representations, which reflect

  1. Supervised neural networks for the classification of structures.

    Science.gov (United States)

    Sperduti, A; Starita, A

    1997-01-01

    Standard neural networks and statistical methods are usually believed to be inadequate when dealing with complex structures because of their feature-based approach. In fact, feature-based approaches usually fail to give satisfactory solutions because of the sensitivity of the approach to the a priori selection of the features, and the incapacity to represent any specific information on the relationships among the components of the structures. However, we show that neural networks can, in fact, represent and classify structured patterns. The key idea underpinning our approach is the use of the so called "generalized recursive neuron", which is essentially a generalization to structures of a recurrent neuron. By using generalized recursive neurons, all the supervised networks developed for the classification of sequences, such as backpropagation through time networks, real-time recurrent networks, simple recurrent networks, recurrent cascade correlation networks, and neural trees can, on the whole, be generalized to structures. The results obtained by some of the above networks (with generalized recursive neurons) on the classification of logic terms are presented.

  2. The pullout performance of pedicle screws

    CERN Document Server

    Demir, Teyfik

    2015-01-01

    This brief book systematically discusses all subjects that affect the pullout strength of pedicle screws. These screws are used in spinal surgeries to stabilize the spine. The holding strength of the pedicle screw is vital since loosening of the pedicle screws can cause revision surgeries. Once the pedicle screw is pulled out, it is harder to obtain same stabilization for the fused vertebrae. The book reviews the effect of screw designs, application techniques, cement augmentation, coating of the screw and test conditions on the pullout strength. The studies with finite element analysis were also included.

  3. Neural coding of sound envelope structure in songbirds.

    Science.gov (United States)

    Boari, Santiago; Amador, Ana

    2017-12-12

    Songbirds are a well-established animal model to study the neural basis of learning, perception and production of complex vocalizations. In this system, telencephalic neurons in HVC present a state-dependent, highly selective response to auditory presentations of the bird's own song (BOS). This property provides an opportunity to study the neural code behind a complex motor behavior. In this work, we explore whether changes in the temporal structure of the sound envelope can drive changes in the neural responses of highly selective HVC units. We generated an envelope-modified BOS (MOD) by reversing each syllable's envelope but leaving the overall temporal structure of syllable spectra unchanged, which resulted in a subtle modification for each song syllable. We conducted in vivo electrophysiological recordings of HVC neurons in anaesthetized zebra finches (Taeniopygia guttata). Units analyzed presented a high BOS selectivity and lower response to MOD, but preserved the profile response shape. These results show that the temporal evolution of the sound envelope is being sensed by the avian song system and suggest that the biomechanical properties of the vocal apparatus could play a role in enhancing subtle sound differences.

  4. Neural network structure for navigation using potential fields

    Science.gov (United States)

    Plumer, Edward S.

    1992-01-01

    A hybrid-network method for obstacle avoidance in the truck-backing system of D. Nguyen and B. Widrow (1989) is presented. A neural network technique for vehicle navigation and control in the presence of obstacles has been developed. A potential function which peaks at the surface of obstacles and has its minimum at the proper vehicle destination is computed using a network structure. The field is guaranteed not to have spurious local minima and does not have the property of flattening-out far from the goal. A feedforward neural network is used to control the steering of the vehicle using local field information. The network is trained in an obstacle-free space to follow the negative gradient of the field, after which the network is able to control and navigate the truck to its target destination in a space of obstacles which may be stationary or movable.

  5. Structure Learning for Deep Neural Networks Based on Multiobjective Optimization.

    Science.gov (United States)

    Liu, Jia; Gong, Maoguo; Miao, Qiguang; Wang, Xiaogang; Li, Hao

    2017-05-05

    This paper focuses on the connecting structure of deep neural networks and proposes a layerwise structure learning method based on multiobjective optimization. A model with better generalization can be obtained by reducing the connecting parameters in deep networks. The aim is to find the optimal structure with high representation ability and better generalization for each layer. Then, the visible data are modeled with respect to structure based on the products of experts. In order to mitigate the difficulty of estimating the denominator in PoE, the denominator is simplified and taken as another objective, i.e., the connecting sparsity. Moreover, for the consideration of the contradictory nature between the representation ability and the network connecting sparsity, the multiobjective model is established. An improved multiobjective evolutionary algorithm is used to solve this model. Two tricks are designed to decrease the computational cost according to the properties of input data. The experiments on single-layer level, hierarchical level, and application level demonstrate the effectiveness of the proposed algorithm, and the learned structures can improve the performance of deep neural networks.

  6. L5 pedicle subtraction osteotomy for high-grade isthmic spondylolisthesis.

    Science.gov (United States)

    Radcliff, Kristen E; Jakoi, Andre M

    2015-04-01

    To the authors' knowledge, this is the first article to present a pedicle subtraction osteotomy in the lumbar spine to correct and stabilize a high-grade isthmic spondylolisthesis, which poses many challenges with regard to treatment options and outcomes. The optimal surgical treatment for high-grade spondylolisthesis is controversial, but the goals of treatment are to stabilize the affected spinal levels and to decompress the neural elements. A pedicle subtraction osteotomy is a reconstructive procedure that addresses fixed sagittal imbalance by increasing lumbar lordosis through posterior spinal column shortening. The authors report a 46-year-old patient with chronic, progressively worsening back and leg radiculopathy accompanied by sagittal plane malalignment and for which a pedicle subtraction osteotomy was performed. The procedure yielded stabilization of the patient's lumbar spondylolisthesis and sagittal plane alignment was restoration. At 3 months postoperatively, the patient's pain had fully resolved and her motor and neurologic examination exhibited no deficits. At 24 months postoperatively, she was still symptom-free and ambulating without assistance. This report is the first documented successful pedicle subtraction osteotomy in the treatment of high-grade spondylolisthesis. This report indicates that certain patient populations may be amenable to pedicle subtraction osteotomy as a treatment option for pathology involving high-grade isthmic spondylolisthesis. Copyright 2015, SLACK Incorporated.

  7. Deep Convolutional Neural Networks: Structure, Feature Extraction and Training

    Directory of Open Access Journals (Sweden)

    Namatēvs Ivars

    2017-12-01

    Full Text Available Deep convolutional neural networks (CNNs are aimed at processing data that have a known network like topology. They are widely used to recognise objects in images and diagnose patterns in time series data as well as in sensor data classification. The aim of the paper is to present theoretical and practical aspects of deep CNNs in terms of convolution operation, typical layers and basic methods to be used for training and learning. Some practical applications are included for signal and image classification. Finally, the present paper describes the proposed block structure of CNN for classifying crucial features from 3D sensor data.

  8. Structural neural substrates of reading the mind in the eyes

    Directory of Open Access Journals (Sweden)

    Wataru eSato

    2016-04-01

    Full Text Available The ability to read the minds of others in their eyes plays an important role in human adaptation to social environments. Behavioral studies have resulted in the development of a test to measure this ability (Reading the Mind in the Eyes Test, revised version; Eyes Test, and have demonstrated that this ability is consistent over time. Although functional neuroimaging studies revealed brain activation while performing the Eyes Test, the structural neural substrates supporting consistent performance on the Eyes Test remain unclear. In this study we assessed the Eyes Test and analyzed structural magnetic resonance images using voxel-based morphometry in healthy participants. Test performance was positively associated with the gray matter volumes of the dorsomedial prefrontal cortex, inferior parietal lobule (temporoparietal junction, and precuneus in the left hemisphere. These results suggest that the fronto-temporoparietal network structures support the consistent ability to read the mind in the eyes.

  9. Self-organization in neural networks - Applications in structural optimization

    Science.gov (United States)

    Hajela, Prabhat; Fu, B.; Berke, Laszlo

    1993-01-01

    The present paper discusses the applicability of ART (Adaptive Resonance Theory) networks, and the Hopfield and Elastic networks, in problems of structural analysis and design. A characteristic of these network architectures is the ability to classify patterns presented as inputs into specific categories. The categories may themselves represent distinct procedural solution strategies. The paper shows how this property can be adapted in the structural analysis and design problem. A second application is the use of Hopfield and Elastic networks in optimization problems. Of particular interest are problems characterized by the presence of discrete and integer design variables. The parallel computing architecture that is typical of neural networks is shown to be effective in such problems. Results of preliminary implementations in structural design problems are also included in the paper.

  10. Is Artificial Neural Network Suitable for Damage Level Determination of Rc- Structures?

    OpenAIRE

    Baltacıoğlu, A. K.; Öztürk, B.; Civalek, Ö.; Akgöz, B.

    2010-01-01

    In the present study, an artificial neural network (ANN) application is introduced for estimation of damage level of reinforced concrete structures. Back-propagation learning algorithm is adopted. A typical neural network architecture is proposed and some conclusions are presented. Applicability of artificial neural network (ANN) for the assessment of earthquake related damage is investigated

  11. Some structural determinants of Pavlovian conditioning in artificial neural networks.

    Science.gov (United States)

    Sánchez, José M; Galeazzi, Juan M; Burgos, José E

    2010-05-01

    This paper investigates the possible role of neuroanatomical features in Pavlovian conditioning, via computer simulations with layered, feedforward artificial neural networks. The networks' structure and functioning are described by a strongly bottom-up model that takes into account the roles of hippocampal and dopaminergic systems in conditioning. Neuroanatomical features were simulated as generic structural or architectural features of neural networks. We focused on the number of units per hidden layer and connectivity. The effect of the number of units per hidden layer was investigated through simulations of resistance to extinction in fully connected networks. Large networks were more resistant to extinction than small networks, a stochastic effect of the asynchronous random procedure used in the simulator to update activations and weights. These networks did not simulate second-order conditioning because weight competition prevented conditioning to a stimulus after conditioning to another. Partially connected networks simulated second-order conditioning and devaluation of the second-order stimulus after extinction of a similar first-order stimulus. Similar stimuli were simulated as nonorthogonal input-vectors. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  12. Structures of Neural Correlation and How They Favor Coding

    Science.gov (United States)

    Franke, Felix; Fiscella, Michele; Sevelev, Maksim; Roska, Botond; Hierlemann, Andreas; da Silveira, Rava Azeredo

    2017-01-01

    Summary The neural representation of information suffers from “noise”—the trial-to-trial variability in the response of neurons. The impact of correlated noise upon population coding has been debated, but a direct connection between theory and experiment remains tenuous. Here, we substantiate this connection and propose a refined theoretical picture. Using simultaneous recordings from a population of direction-selective retinal ganglion cells, we demonstrate that coding benefits from noise correlations. The effect is appreciable already in small populations, yet it is a collective phenomenon. Furthermore, the stimulus-dependent structure of correlation is key. We develop simple functional models that capture the stimulus-dependent statistics. We then use them to quantify the performance of population coding, which depends upon interplays of feature sensitivities and noise correlations in the population. Because favorable structures of correlation emerge robustly in circuits with noisy, nonlinear elements, they will arise and benefit coding beyond the confines of retina. PMID:26796692

  13. Crystal Structure Representation for Neural Networks using Topological Approach.

    Science.gov (United States)

    Fedorov, Aleksandr V; Shamanaev, Ivan V

    2017-08-01

    In the present work we describe a new approach, which uses topology of crystals for physicochemical properties prediction using artificial neural networks (ANN). The topologies of 268 crystal structures were determined using ToposPro software. Quotient graphs were used to identify topological centers and their neighbors. The topological approach was illustrated by training ANN to predict molar heat capacity, standard molar entropy and lattice energy of 268 crystals with different compositions and structures (metals, inorganic salts, oxides, etc.). ANN was trained using Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm. Mean absolute percentage error of predicted properties was ≤8 %. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Simulation of morphologically structured photo-thermal neural stimulation

    Science.gov (United States)

    Weissler, Y.; Farah, N.; Shoham, S.

    2017-10-01

    Objective. Rational design of next-generation techniques for photo-thermal excitation requires the development of tools capable of modeling the effects of spatially- and temporally-dependent temperature distribution on cellular neuronal structures. Approach. We present a new computer simulation tool for predicting the effects of arbitrary spatiotemporally-structured photo-thermal stimulation on 3D, morphologically realistic neurons. The new simulation tool is based on interfacing two generic platforms, NEURON and MATLAB and is therefore suited for capturing different kinds of stimuli and neural models. Main results. Simulation results are validated using photo-absorber induced neuro-thermal stimulation (PAINTS) empirical results, and advanced features are explored. Significance. The new simulation tool could have an important role in understanding and investigating complex optical stimulation at the single-cell and network levels.

  15. Neural networks for harmonic structure in music perception and action.

    Science.gov (United States)

    Bianco, R; Novembre, G; Keller, P E; Kim, Seung-Goo; Scharf, F; Friederici, A D; Villringer, A; Sammler, D

    2016-11-15

    The ability to predict upcoming structured events based on long-term knowledge and contextual priors is a fundamental principle of human cognition. Tonal music triggers predictive processes based on structural properties of harmony, i.e., regularities defining the arrangement of chords into well-formed musical sequences. While the neural architecture of structure-based predictions during music perception is well described, little is known about the neural networks for analogous predictions in musical actions and how they relate to auditory perception. To fill this gap, expert pianists were presented with harmonically congruent or incongruent chord progressions, either as musical actions (photos of a hand playing chords) that they were required to watch and imitate without sound, or in an auditory format that they listened to without playing. By combining task-based functional magnetic resonance imaging (fMRI) with functional connectivity at rest, we identified distinct sub-regions in right inferior frontal gyrus (rIFG) interconnected with parietal and temporal areas for processing action and audio sequences, respectively. We argue that the differential contribution of parietal and temporal areas is tied to motoric and auditory long-term representations of harmonic regularities that dynamically interact with computations in rIFG. Parsing of the structural dependencies in rIFG is co-determined by both stimulus- or task-demands. In line with contemporary models of prefrontal cortex organization and dual stream models of visual-spatial and auditory processing, we show that the processing of musical harmony is a network capacity with dissociated dorsal and ventral motor and auditory circuits, which both provide the infrastructure for predictive mechanisms optimising action and perception performance. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Neural Network Enhanced Structure Determination of Osteoporosis, Immune System, and Radiation Repair Proteins Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation will utilize self learning neural network technology to determine the structure of osteoporosis, immune system disease, and excess radiation...

  17. Fuzzy stochastic neural network model for structural system identification

    Science.gov (United States)

    Jiang, Xiaomo; Mahadevan, Sankaran; Yuan, Yong

    2017-01-01

    This paper presents a dynamic fuzzy stochastic neural network model for nonparametric system identification using ambient vibration data. The model is developed to handle two types of imprecision in the sensed data: fuzzy information and measurement uncertainties. The dimension of the input vector is determined by using the false nearest neighbor approach. A Bayesian information criterion is applied to obtain the optimum number of stochastic neurons in the model. A fuzzy C-means clustering algorithm is employed as a data mining tool to divide the sensed data into clusters with common features. The fuzzy stochastic model is created by combining the fuzzy clusters of input vectors with the radial basis activation functions in the stochastic neural network. A natural gradient method is developed based on the Kullback-Leibler distance criterion for quick convergence of the model training. The model is validated using a power density pseudospectrum approach and a Bayesian hypothesis testing-based metric. The proposed methodology is investigated with numerically simulated data from a Markov Chain model and a two-story planar frame, and experimentally sensed data from ambient vibration data of a benchmark structure.

  18. Diathermy excisional hemorrhoidectomy: a prospective randomized study comparing pedicle ligation and pedicle coagulation.

    Science.gov (United States)

    Bessa, Samer S

    2011-11-01

    In hemorrhoidectomy, pedicle coagulation has been claimed to be associated with less postoperative pain compared with pedicle ligation. This study was designed to compare the effects of pedicle ligation vs pedicle coagulation on postoperative pain in patients undergoing diathermy excisional hemorrhoidectomy. The study was conducted as a single-blind prospective randomized clinical trial. Patients were treated at a single tertiary-level teaching hospital (Main University Hospital) in Alexandria, Egypt, from February 2009 to October 2010. Patients with symptomatic grade III or IV hemorrhoids were eligible. Patients were randomly allocated to receive either pedicle coagulation or pedicle ligation during 3-quadrant diathermy excision hemorrhoidectomy. Patients reported postoperative pain daily on a visual analog scale (0-10, with 10 corresponding to the most severe pain) during the first 10 postoperative days. On-demand parenteral analgesic requirements were recorded during the first 24 hours after surgery. Operative time, postoperative complications, and wound healing rates at 6 weeks postoperatively were also recorded. No a priori power calculation could be performed, so it was not possible to tell whether nonsignificant differences were real or a result of chance. A total of 136 patients were randomly assigned, and 120 patients completed the study (60 in each group). The overall median pain score for the first 10 postoperative days was significantly lower in the pedicle coagulation group than in the pedicle ligation group (4.65 vs 6.56, P parenteral analgesic requirements during the first 24 hours postoperatively.

  19. Direct Adaptive Aircraft Control Using Dynamic Cell Structure Neural Networks

    Science.gov (United States)

    Jorgensen, Charles C.

    1997-01-01

    A Dynamic Cell Structure (DCS) Neural Network was developed which learns topology representing networks (TRNS) of F-15 aircraft aerodynamic stability and control derivatives. The network is integrated into a direct adaptive tracking controller. The combination produces a robust adaptive architecture capable of handling multiple accident and off- nominal flight scenarios. This paper describes the DCS network and modifications to the parameter estimation procedure. The work represents one step towards an integrated real-time reconfiguration control architecture for rapid prototyping of new aircraft designs. Performance was evaluated using three off-line benchmarks and on-line nonlinear Virtual Reality simulation. Flight control was evaluated under scenarios including differential stabilator lock, soft sensor failure, control and stability derivative variations, and air turbulence.

  20. Resolution of Singularities Introduced by Hierarchical Structure in Deep Neural Networks.

    Science.gov (United States)

    Nitta, Tohru

    2017-10-01

    We present a theoretical analysis of singular points of artificial deep neural networks, resulting in providing deep neural network models having no critical points introduced by a hierarchical structure. It is considered that such deep neural network models have good nature for gradient-based optimization. First, we show that there exist a large number of critical points introduced by a hierarchical structure in deep neural networks as straight lines, depending on the number of hidden layers and the number of hidden neurons. Second, we derive a sufficient condition for deep neural networks having no critical points introduced by a hierarchical structure, which can be applied to general deep neural networks. It is also shown that the existence of critical points introduced by a hierarchical structure is determined by the rank and the regularity of weight matrices for a specific class of deep neural networks. Finally, two kinds of implementation methods of the sufficient conditions to have no critical points are provided. One is a learning algorithm that can avoid critical points introduced by the hierarchical structure during learning (called avoidant learning algorithm). The other is a neural network that does not have some critical points introduced by the hierarchical structure as an inherent property (called avoidant neural network).

  1. Primary pedicle screw augmentation in osteoporotic lumbar vertebrae: biomechanical analysis of pedicle fixation strength.

    Science.gov (United States)

    Burval, Daniel J; McLain, Robert F; Milks, Ryan; Inceoglu, Serkan

    2007-05-01

    Pedicle screw pullout testing in osteoporotic and control human cadaveric vertebrae, comparing augmented and control vertebrae. To compare the pullout strengths of pedicle screws fixed in osteoporotic vertebrae using polymethyl methacrylate delivered by 2 augmentation techniques, a standard transpedicular approach and kyphoplasty type approach. Pedicle screw instrumentation of the osteoporotic spine carries an increased risk of screw loosening, pullout, and fixation failure. Osteoporosis is often cited as a contraindication for pedicle screw fixation. Augmentation of the vertebral pedicle and body using polymethyl methacrylate may improve fixation strength and construct survival in the osteoporotic vertebrae. While the utility of polymethyl methacrylate has been demonstrated for salvage of screws that have been pulled out, the effect of the cement technique on pullout strength in osteoporotic vertebrae has not been previously studied. Thirteen osteoporotic and 9 healthy human lumbar vertebrae were tested. All specimens were instrumented with pedicle screws using a uniform technique. Osteoporotic pedicles were augmented with polymethyl methacrylate using either a kyphoplasty type technique or a transpedicular augmentation technique. Screws were tested in a paired testing array, randomly assigning the augmentation techniques to opposite sides of each vertebra. Pullout to failure was performed either primarily or after a 5000-cycle tangential fatigue conditioning exposure. After testing, following screw removal, specimens were cut in the axial plane through the center of the vertebral body to inspect the cement distribution. Pedicle screws placed in osteoporotic vertebrae had higher pullout loads when augmented with the kyphoplasty technique compared to transpedicular augmentation (1414 +/- 338 versus 756 +/- 300 N, respectively; P cycling. Pedicle screw augmentation with polymethyl methacrylate improves the initial fixation strength and fatigue strength of

  2. Learning Orthographic Structure With Sequential Generative Neural Networks.

    Science.gov (United States)

    Testolin, Alberto; Stoianov, Ivilin; Sperduti, Alessandro; Zorzi, Marco

    2016-04-01

    Learning the structure of event sequences is a ubiquitous problem in cognition and particularly in language. One possible solution is to learn a probabilistic generative model of sequences that allows making predictions about upcoming events. Though appealing from a neurobiological standpoint, this approach is typically not pursued in connectionist modeling. Here, we investigated a sequential version of the restricted Boltzmann machine (RBM), a stochastic recurrent neural network that extracts high-order structure from sensory data through unsupervised generative learning and can encode contextual information in the form of internal, distributed representations. We assessed whether this type of network can extract the orthographic structure of English monosyllables by learning a generative model of the letter sequences forming a word training corpus. We show that the network learned an accurate probabilistic model of English graphotactics, which can be used to make predictions about the letter following a given context as well as to autonomously generate high-quality pseudowords. The model was compared to an extended version of simple recurrent networks, augmented with a stochastic process that allows autonomous generation of sequences, and to non-connectionist probabilistic models (n-grams and hidden Markov models). We conclude that sequential RBMs and stochastic simple recurrent networks are promising candidates for modeling cognition in the temporal domain. Copyright © 2015 Cognitive Science Society, Inc.

  3. Z(2) gauge neural network and its phase structure

    Science.gov (United States)

    Takafuji, Yusuke; Nakano, Yuki; Matsui, Tetsuo

    2012-11-01

    We study general phase structures of neural-network models that have Z(2) local gauge symmetry. The Z(2) spin variable Si=±1 on the i-th site describes a neuron state as in the Hopfield model, and the Z(2) gauge variable J=±1 describes a state of the synaptic connection between j-th and i-th neurons. The gauge symmetry allows for a self-coupling energy among J’s such as JJJ, which describes reverberation of signals. Explicitly, we consider the three models; (I) an annealed model with full and partial connections of J, (II) a quenched model with full connections where J is treated as a slow quenched variable, and (III) a quenched three-dimensional lattice model with the nearest-neighbor connections. By numerical simulations, we examine their phase structures paying attention to the effect of the reverberation term, and compare them with each other and with the annealed 3D lattice model which has been studied beforehand. By noting the dependence of thermodynamic quantities upon the total number of sites and the connectivity among sites, we obtain a coherent interpretation to understand these results. Among other things, we find that the Higgs phase of the annealed model is separated into two stable spin-glass phases in the quenched models (II) and (III).

  4. Cadaveric study for ideal dorsal pedicle screw entry point

    Directory of Open Access Journals (Sweden)

    Sandeep Sonone

    2017-01-01

    Conclusion: We conclude that the ideal pedicle entry point described here should be considered by surgeons during thoracic pedicle screw instrumentation. The notch at the base of the superior articular process will always remain constant and therefore an important anatomical landmark in guiding the screw toward the entry of the pedicle.

  5. The relevance of network micro-structure for neural dynamics

    Directory of Open Access Journals (Sweden)

    Volker ePernice

    2013-06-01

    Full Text Available The activity of cortical neurons is determined by the input they receive from presynaptic neurons. Many previousstudies have investigated how specific aspects of the statistics of the input affect the spike trains of single neurons and neuronsin recurrent networks. However, typically very simple random network models are considered in such studies. Here weuse a recently developed algorithm to construct networks based on a quasi-fractal probability measure which are much morevariable than commonly used network models, and which therefore promise to sample the space of recurrent networks ina more exhaustive fashion than previously possible. We use the generated graphs as the underlying network topology insimulations of networks of integrate-and-fire neurons in an asynchronous and irregular state. Based on an extensive datasetof networks and neuronal simulations we assess statistical relations between features of the network structure and the spikingactivity. Our results highlight the strong influence that some details of the network structure have on the activity dynamics ofboth single neurons and populations, even if some global network parameters are kept fixed. We observe specific and consistentrelations between activity characteristics like spike-train irregularity or correlations and network properties, for example thedistributions of the numbers of in- and outgoing connections or clustering. Exploiting these relations, we demonstrate that itis possible to estimate structural characteristics of the network from activity data. We also assess higher order correlationsof spiking activity in the various networks considered here, and find that their occurrence strongly depends on the networkstructure. These results provide directions for further theoretical studies on recurrent networks, as well as new ways to interpretspike train recordings from neural circuits.

  6. Salvage of extensively burned upper limbs by a pedicled latissimus dorsi flap.

    Science.gov (United States)

    Delay, E; Foyatier, J L; el Kollali, R; Comparin, J P; Weil, E; Latarjet, J

    1995-09-01

    Very deep burns of the arm and elbow lead to soft tissue necrosis and infection with exposure of important structures. Aggressive debridement should be performed as early as possible to cut the vicious circle, and the defect, which may be extensive, should be covered by well-vascularized tissues. The reliability and versatility of the pedicled latissimus dorsi muscle or musculocutaneous flap make it our first choice in the management of this problem. A retrospective study of three patients for whom salvage of the upper limb has been achieved by the use of a pedicled latissimus dorsi flap is presented, illustrating the advantages of this technique.

  7. Interactive extraction of neural structures with user-guided morphological diffusion

    KAUST Repository

    Yong Wan,

    2012-10-01

    Extracting neural structures with their fine details from confocal volumes is essential to quantitative analysis in neurobiology research. Despite the abundance of various segmentation methods and tools, for complex neural structures, both manual and semi-automatic methods are ine ective either in full 3D or when user interactions are restricted to 2D slices. Novel interaction techniques and fast algorithms are demanded by neurobiologists to interactively and intuitively extract neural structures from confocal data. In this paper, we present such an algorithm-technique combination, which lets users interactively select desired structures from visualization results instead of 2D slices. By integrating the segmentation functions with a confocal visualization tool neurobiologists can easily extract complex neural structures within their typical visualization workflow.

  8. [Are C2 pedicles always screwable? Calibration and planning with a pedicle-lamina angle].

    Science.gov (United States)

    Le Pape, S; Gauthe, R; Latrobe, C; Cantogrel, P; Proust, F; Leroux, J; Ould-Slimane, M

    2016-08-01

    Posterior cervical arthrodesis is associated with osteosynthesis. C2 pedicular screwing affords a good bone anchoring but involves neurological and vascular risks. To determine C2 pedicular screwing feasibility from a large cohort of cervical CT scans. To describe the visible anatomical parameters during a surgical procedure in order to plan and secure it. Retrospective consecutive series of 100 cervical CT scans was analyzed. Cases with upper cervical fracture were excluded. C2 surgical anatomy was assessed according to maximum length, minimum width and minimum height. Angular parameters were pedicle-transverse angle and sagittal angle. Original pedicle-lamina angle was used as a visible mark during the procedure independent of the patient's position. Pedicular screwing feasibility was evaluated. It was arbitrarily defined by a lower minimum height less than 4mm. Two hundred C2 pedicles were analyzed with 7.5% that were not screwable. Their mean length was 26.2mm, with a mean width of 5.2mm and a mean height of 9.2mm. Mean pedicle-transverse angle was 36.2°, mean sagittal angle was 25.8° and mean pedicle-lamina angle was 81.3°. C2 pedicle screwing feasibility is inconstant due to anatomical variability. In fact, 13% of patients have at least one non-screwable pedicle. Preoperative planning is essential to achieve this procedure. A pedicle-lamina angle can be used which remains independent from the patient's position. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  9. Structuring a multi-nodal neural network in vitro within a novel design microfluidic chip.

    Science.gov (United States)

    van de Wijdeven, Rosanne; Ramstad, Ola Huse; Bauer, Ulrich Stefan; Halaas, Øyvind; Sandvig, Axel; Sandvig, Ioanna

    2018-01-02

    Neural network formation is a complex process involving axon outgrowth and guidance. Axon guidance is facilitated by structural and molecular cues from the surrounding microenvironment. Micro-fabrication techniques can be employed to produce microfluidic chips with a highly controlled microenvironment for neural cells enabling longitudinal studies of complex processes associated with network formation. In this work, we demonstrate a novel open microfluidic chip design that encompasses a freely variable number of nodes interconnected by axon-permissible tunnels, enabling structuring of multi-nodal neural networks in vitro. The chip employs a partially open design to allow high level of control and reproducibility of cell seeding, while reducing shear stress on the cells. We show that by culturing dorsal root ganglion cells (DRGs) in our microfluidic chip, we were able to structure a neural network in vitro. These neurons were compartmentalized within six nodes interconnected through axon growth tunnels. Furthermore, we demonstrate the additional benefit of open top design by establishing a 3D neural culture in matrigel and a neuronal aggregate 3D culture within the chips. In conclusion, our results demonstrate a novel microfluidic chip design applicable to structuring complex neural networks in vitro, thus providing a versatile, highly relevant platform for the study of neural network dynamics applicable to developmental and regenerative neuroscience.

  10. Ambiguity resolution in a Neural Blackboard Architecture for sentence structure

    NARCIS (Netherlands)

    van der Velde, Frank; van der Velde, Frank; de Kamps, Marc; Besold, Tarek R.; Kühnberger, Kai-Uwe

    2015-01-01

    We simulate two examples of ambiguity resolution found in human language processing in a neural blackboard architecture for sentence representation and processing. The architecture also accounts for a related garden path effect. The architecture represents and processes sentences in terms of

  11. Thoracic pedicle morphometry in vertebrae from scoliotic spines.

    Science.gov (United States)

    Parent, Stefan; Labelle, Hubert; Skalli, Wafa; de Guise, Jacques

    2004-02-01

    A morphometric analysis of thoracic pedicles in vertebrae from scoliotic specimens. The objective of this study was to quantify the changes occurring in thoracic pedicles affected by a scoliotic deformity. There exists a lot of controversy in the literature concerning the shape and size of thoracic pedicles in idiopathic scoliosis. In recent years, thoracic pedicle screws are being used more frequently in corrective spine surgery, but few studies have evaluated the morphology of scoliotic thoracic pedicles. Thirty scoliotic specimens with curves presenting various degrees of severity were studied using a three-dimensional digitizing protocol developed to create a precise three-dimensional reconstruction of the vertebrae. Twenty-two parameters describing specifically the pedicles were then calculated for each vertebra from these reconstructions. Every scoliotic specimen was then matched with a normal specimen to provide for a representative control group and comparisons were made on pedicle width, length, height, surface, and orientation. A total of 683 thoracic vertebrae were measured (325 scoliotic and 358 normal vertebrae). Pedicles located on the concavity of typical right thoracic curves were found to be significantly thinner than their normal counterparts with a maximal mean difference of 1.37 mm at T8. The pedicles on the concavity of the high thoracic compensatory curve were also found to be significantly diminished with a maximal mean difference of 1.68 mm at T4. Mean left pedicle width at T8 (concavity) and mean right pedicle width at T4 (concavity) were found to be 4.08 mm and 2.60 mm, respectively. Pedicle length was found to be slightly increased, and pedicle height was found to be slightly decreased in pedicles from scoliotic spines with no preference for concavity or convexity. Pedicle orientation and inclination were unchanged with respect to each corresponding vertebral body. These results are of critical importance for clinicians performing spinal

  12. Cognitive Flexibility through Metastable Neural Dynamics Is Disrupted by Damage to the Structural Connectome

    Science.gov (United States)

    Hellyer, Peter J.; Scott, Gregory; Shanahan, Murray; Sharp, David J.

    2015-01-01

    Current theory proposes that healthy neural dynamics operate in a metastable regime, where brain regions interact to simultaneously maximize integration and segregation. Metastability may confer important behavioral properties, such as cognitive flexibility. It is increasingly recognized that neural dynamics are constrained by the underlying structural connections between brain regions. An important challenge is, therefore, to relate structural connectivity, neural dynamics, and behavior. Traumatic brain injury (TBI) is a pre-eminent structural disconnection disorder whereby traumatic axonal injury damages large-scale connectivity, producing characteristic cognitive impairments, including slowed information processing speed and reduced cognitive flexibility, that may be a result of disrupted metastable dynamics. Therefore, TBI provides an experimental and theoretical model to examine how metastable dynamics relate to structural connectivity and cognition. Here, we use complementary empirical and computational approaches to investigate how metastability arises from the healthy structural connectome and relates to cognitive performance. We found reduced metastability in large-scale neural dynamics after TBI, measured with resting-state functional MRI. This reduction in metastability was associated with damage to the connectome, measured using diffusion MRI. Furthermore, decreased metastability was associated with reduced cognitive flexibility and information processing. A computational model, defined by empirically derived connectivity data, demonstrates how behaviorally relevant changes in neural dynamics result from structural disconnection. Our findings suggest how metastable dynamics are important for normal brain function and contingent on the structure of the human connectome. PMID:26085630

  13. Application of structured support vector machine backpropagation to a convolutional neural network for human pose estimation.

    Science.gov (United States)

    Witoonchart, Peerajak; Chongstitvatana, Prabhas

    2017-08-01

    In this study, for the first time, we show how to formulate a structured support vector machine (SSVM) as two layers in a convolutional neural network, where the top layer is a loss augmented inference layer and the bottom layer is the normal convolutional layer. We show that a deformable part model can be learned with the proposed structured SVM neural network by backpropagating the error of the deformable part model to the convolutional neural network. The forward propagation calculates the loss augmented inference and the backpropagation calculates the gradient from the loss augmented inference layer to the convolutional layer. Thus, we obtain a new type of convolutional neural network called an Structured SVM convolutional neural network, which we applied to the human pose estimation problem. This new neural network can be used as the final layers in deep learning. Our method jointly learns the structural model parameters and the appearance model parameters. We implemented our method as a new layer in the existing Caffe library. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Blood flow autoregulation in pedicled flaps

    DEFF Research Database (Denmark)

    Bonde, Christian T; Holstein-Rathlou, Niels-Henrik; Elberg, Jens J

    2009-01-01

    INTRODUCTION: Clinical work on the blood perfusion in skin and muscle flaps has suggested that some degree of blood flow autoregulation exists in such flaps. An autoregulatory mechanism would enable the flap to protect itself from changes in the perfusion pressure. The purpose of the present study...... was to evaluate if, and to what extent, a tissue flap could compensate a reduction in blood flow due to an acute constriction of the feed artery. Further, we wanted to examine the possible role of smooth muscle L-type calcium channels in the autoregulatory mechanism by pharmacological intervention with the L......-type calcium channel blocker nimodipine and the vasodilator papaverine. MATERIAL AND METHODS: Pedicled flaps were raised in pigs. Flow in the pedicle was reduced by constriction of the feed artery (n=34). A transit time flow probe measured the effect on blood flow continuously. Following this, three different...

  15. What is the Difference in Morphologic Features of the Thoracic Pedicle Between Patients With Adolescent Idiopathic Scoliosis and Healthy Subjects? A CT-based Case-control Study.

    Science.gov (United States)

    Gao, Bo; Gao, Wenjie; Chen, Chong; Wang, Qinghua; Lin, Shaochun; Xu, Caixia; Huang, Dongsheng; Su, Peiqiang

    2017-11-01

    Describing the morphologic features of the thoracic pedicle in patients with adolescent idiopathic scoliosis is necessary for placement of pedicle screws. Previous studies showed inadequate reliability owing to small sample size and heterogeneity of the patients surveyed. To use CT scans (1) to describe the morphologic features of 2718 thoracic pedicles from 60 female patients with Lenke Type 1 adolescent idiopathic scoliosis and 60 age-, sex-, and height-matched controls; and (2) to classify the pedicles in three types based on pedicle width and analyze the distribution of each type. A total of 2718 pedicles from 60 female patients with Lenke Type 1 adolescent idiopathic scoliosis and 60 matched female controls were analyzed via CT. All patients surveyed were diagnosed with adolescent idiopathic scoliosis, Lenke Type 1, at the First Affiliated Hospital of Sun Yat-sen University, and all underwent pedicle screw fixation between January 2008 and December 2013 with preoperative radiographs and CT images on file. We routinely obtained CT scans before these procedures; all patients who underwent surgery during that period had CT scans, and all were available for analysis here. Control subjects had CT scans for other clinical indications and had no abnormal findings of the spine. The control subjects were chosen to match patients in terms of age (15 ± 2.6 years versus 15 ± 2.6 years) and sex. Height of the two groups also was matched (154 ± 9 cm versus 155 ± 10 cm; mean difference, -1.06 cm; 95% CI, -1.24 to -0.81 cm; p scoliosis (22%; 293 of 1322) compared with controls (13%; 178 of 1396) (odds ratio [OR] = 0.51; 95% CI, 0.42-0.63; p scoliosis, they commonly occurred on the concave side 34% (228 of 661) and on the AV-SC region (32%; 43 of 136). Pedicle width on the concave side was narrower than pedicle width on the convex side and pedicle width in healthy control subjects. The apical vertebra in the structural curve was the most variegated region of the curve with

  16. An object recognition using structured light and neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Byeong Gab; Kim, Dong Gi; Kang, E Sok [Chungnam National Univ., Taejon (Korea, Republic of); Yoon, Ji Sup [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    This paper presents a 3D image processing which uses neural networks to combine a 2D vision camera and a laser slit beam. A laser slit beam from laser source is slitted by a set of cylindrical lenses and the line image of the networks allow to get the 3D image parameters such as the size, the position and the orientation from the line image without knowing the camera intrinsic parameters. (author). 7 refs., 3 tabs., 5 figs.

  17. Précis of Neural organization: structure, function, and dynamics.

    Science.gov (United States)

    Arbib, M A; Erdi, P

    2000-08-01

    NEURAL ORGANIZATION: Structure, function, and dynamics shows how theory and experiment can supplement each other in an integrated, evolving account of the brain's structure, function, and dynamics. (1) STRUCTURE: Studies of brain function and dynamics build on and contribute to an understanding of many brain regions, the neural circuits that constitute them, and their spatial relations. We emphasize Szentágothai's modular architectonics principle, but also stress the importance of the microcomplexes of cerebellar circuitry and the lamellae of hippocampus. (2) FUNCTION: Control of eye movements, reaching and grasping, cognitive maps, and the roles of vision receive a functional decomposition in terms of schemas. Hypotheses as to how each schema is implemented through the interaction of specific brain regions provide the basis for modeling the overall function by neural networks constrained by neural data. Synthetic PET integrates modeling of primate circuitry with data from human brain imaging. (3) DYNAMICS: Dynamic system theory analyzes spatiotemporal neural phenomena, such as oscillatory and chaotic activity in both single neurons and (often synchronized) neural networks, the self-organizing development and plasticity of ordered neural structures, and learning and memory phenomena associated with synaptic modification. Rhythm generation involves multiple levels of analysis, from intrinsic cellular processes to loops involving multiple brain regions. A variety of rhythms are related to memory functions. The Précis presents a multifaceted case study of the hippocampus. We conclude with the claim that language and other cognitive processes can be fruitfully studied within the framework of neural organization that the authors have charted with John Szentágothai.

  18. The rate of screw misplacement in segmental pedicle screw fixation in adolescent idiopathic scoliosis.

    Science.gov (United States)

    Abul-Kasim, Kasim; Ohlin, Acke

    2011-02-01

    There are no reports in the literature on the influence of learning on the pedicle screw insertion. We studied the effect of learning on the rate of screw misplacement in patients with adolescent idiopathic scoliosis treated with segmental pedicle screw fixation. We retrospectively evaluated low-dose spine computed tomography of 116 consecutive patients (aged 16 (12-24) years, 94 females) who were operated during 4 periods over 2005-2009 (group 1: patients operated autumn 2005-2006; group 2: 2007; group 3: 2008; and group 4: 2009). 5 types of misplacement were recorded: medial cortical perforation, lateral cortical perforation, anterior cortical perforation of the vertebral body, endplate perforation, and perforation of the neural foramen. 2,201 pedicle screws were evaluated, with an average of 19 screws per patient. The rate of screw misplacement for the whole study was 14%. The rate of lateral and medial cortical perforation was 7% and 5%. There was an inverse correlation between the occurrence of misplacement and the patient number, i.e. the date of operation (r = -0.35; p skillfulness of screw insertion improved with reduction of the rate of screw misplacement from 20% in 2005-2006 to 11% in 2009, with a breakpoint at the end of the first study period (34 patients). We found a substantial learning curve; cumulative experience may have contributed to continued reduction of misplacement rate.

  19. Design of three-dimensional visualization based on the posterior lumbar pedicle screw fixation

    Directory of Open Access Journals (Sweden)

    Kai XU

    2011-09-01

    Full Text Available Objective To establish a three-dimensional visualization model of posterior lumbar pedicle screw fixation.Methods A patient with lumbar intervertebral disc hernia and another patient with compression fracture of lumbar vertebra were involved in the present study.Both patients underwent multi-slice spiral CT scan before and after lumbar pedicle screw fixation.The degree of preoperative vertebral compression,vertebral morphology before and after surgery,postoperative pedicle screw position,and decompression effects were observed.The original data of the multi-slice spiral CT were inputted into the computer.The three-dimensional reconstructed images of the lumbar and implanted screws were obtained using the software Amira 4.1 to show the three-dimensional shape of the lumbar vertebrae before and after surgery and the location of the implanted screws.Results The morphology and structure of the lumbar vertebrae before and after surgery and of the implanted screws were reconstructed using the digital navigation platform.The reconstructed 3D images could be displayed in multicolor,transparent,or arbitrary combinations.In the 3D surface reconstruction images,the location and structure of the implanted screws could be clearly observed,and the decompression of the spinal cord or nerve roots and the severity of the fracture and the compression of lumbar vertebrae could be fully evaluated.The reconstructed images before operation revealed the position of the vertebral pedicles and provided reference for intraoperative localization.Conclusions The three-dimensional computerized reconstructions of lumbar pedicle screw fixation may be valuable in basic research,clinical experiment,and surgical planning.The software Amira is one of the bases of three-dimensional reconstruction.

  20. A Neural Network Model of the Structure and Dynamics of Human Personality

    Science.gov (United States)

    Read, Stephen J.; Monroe, Brian M.; Brownstein, Aaron L.; Yang, Yu; Chopra, Gurveen; Miller, Lynn C.

    2010-01-01

    We present a neural network model that aims to bridge the historical gap between dynamic and structural approaches to personality. The model integrates work on the structure of the trait lexicon, the neurobiology of personality, temperament, goal-based models of personality, and an evolutionary analysis of motives. It is organized in terms of two…

  1. Puzzle Pieces: Neural Structure and Function in Prader-Willi Syndrome

    Science.gov (United States)

    Manning, Katherine E.; Holland, Anthony J.

    2015-01-01

    Prader-Willi syndrome (PWS) is a neurodevelopmental disorder of genomic imprinting, presenting with a behavioural phenotype encompassing hyperphagia, intellectual disability, social and behavioural difficulties, and propensity to psychiatric illness. Research has tended to focus on the cognitive and behavioural investigation of these features, and, with the exception of eating behaviour, the neural physiology is currently less well understood. A systematic review was undertaken to explore findings relating to neural structure and function in PWS, using search terms designed to encompass all published articles concerning both in vivo and post-mortem studies of neural structure and function in PWS. This supported the general paucity of research in this area, with many articles reporting case studies and qualitative descriptions or focusing solely on the overeating behaviour, although a number of systematic investigations were also identified. Research to date implicates a combination of subcortical and higher order structures in PWS, including those involved in processing reward, motivation, affect and higher order cognitive functions, with both anatomical and functional investigations indicating abnormalities. It appears likely that PWS involves aberrant activity across distributed neural networks. The characterisation of neural structure and function warrants both replication and further systematic study. PMID:28943631

  2. Puzzle Pieces: Neural Structure and Function in Prader-Willi Syndrome

    Directory of Open Access Journals (Sweden)

    Katherine E. Manning

    2015-12-01

    Full Text Available Prader-Willi syndrome (PWS is a neurodevelopmental disorder of genomic imprinting, presenting with a behavioural phenotype encompassing hyperphagia, intellectual disability, social and behavioural difficulties, and propensity to psychiatric illness. Research has tended to focus on the cognitive and behavioural investigation of these features, and, with the exception of eating behaviour, the neural physiology is currently less well understood. A systematic review was undertaken to explore findings relating to neural structure and function in PWS, using search terms designed to encompass all published articles concerning both in vivo and post-mortem studies of neural structure and function in PWS. This supported the general paucity of research in this area, with many articles reporting case studies and qualitative descriptions or focusing solely on the overeating behaviour, although a number of systematic investigations were also identified. Research to date implicates a combination of subcortical and higher order structures in PWS, including those involved in processing reward, motivation, affect and higher order cognitive functions, with both anatomical and functional investigations indicating abnormalities. It appears likely that PWS involves aberrant activity across distributed neural networks. The characterisation of neural structure and function warrants both replication and further systematic study.

  3. Neuromodulatory connectivity defines the structure of a behavioral neural network.

    Science.gov (United States)

    Diao, Feici; Elliott, Amicia D; Diao, Fengqiu; Shah, Sarav; White, Benjamin H

    2017-11-22

    Neural networks are typically defined by their synaptic connectivity, yet synaptic wiring diagrams often provide limited insight into network function. This is due partly to the importance of non-synaptic communication by neuromodulators, which can dynamically reconfigure circuit activity to alter its output. Here, we systematically map the patterns of neuromodulatory connectivity in a network that governs a developmentally critical behavioral sequence in Drosophila. This sequence, which mediates pupal ecdysis, is governed by the serial release of several key factors, which act both somatically as hormones and within the brain as neuromodulators. By identifying and characterizing the functions of the neuronal targets of these factors, we find that they define hierarchically organized layers of the network controlling the pupal ecdysis sequence: a modular input layer, an intermediate central pattern generating layer, and a motor output layer. Mapping neuromodulatory connections in this system thus defines the functional architecture of the network.

  4. Scrotal Reconstruction with a Pedicled Gracilis Muscle Flap after ...

    African Journals Online (AJOL)

    We report a case of a 34 year old African male who presented as a referral from a district hospital with a scrotal defect and exposed testes following extensive debridement of Fournier's gangrene. Scrotal reconstruction with a pedicled gracilis muscle flap was done. The pedicled gracilis muscle flap is close to the scrotal area ...

  5. Traumatic Fracture of Thin Pedicles Secondary to Extradural ...

    African Journals Online (AJOL)

    Our objective is to report a technical case report, illustrating a traumatic spinal injury with multiple pedicle fractures, secondary to atrophic lumbar pedicles as well as the diagnostic workup and surgical management of this problem. Posterior lumbar decompression, resection of the meningeal cyst, ligation of the cyst ostium, ...

  6. Universal transition from unstructured to structured neural maps.

    Science.gov (United States)

    Weigand, Marvin; Sartori, Fabio; Cuntz, Hermann

    2017-05-16

    Neurons sharing similar features are often selectively connected with a higher probability and should be located in close vicinity to save wiring. Selective connectivity has, therefore, been proposed to be the cause for spatial organization in cortical maps. Interestingly, orientation preference (OP) maps in the visual cortex are found in carnivores, ungulates, and primates but are not found in rodents, indicating fundamental differences in selective connectivity that seem unexpected for closely related species. Here, we investigate this finding by using multidimensional scaling to predict the locations of neurons based on minimizing wiring costs for any given connectivity. Our model shows a transition from an unstructured salt-and-pepper organization to a pinwheel arrangement when increasing the number of neurons, even without changing the selectivity of the connections. Increasing neuronal numbers also leads to the emergence of layers, retinotopy, or ocular dominance columns for the selective connectivity corresponding to each arrangement. We further show that neuron numbers impact overall interconnectivity as the primary reason for the appearance of neural maps, which we link to a known phase transition in an Ising-like model from statistical mechanics. Finally, we curated biological data from the literature to show that neural maps appear as the number of neurons in visual cortex increases over a wide range of mammalian species. Our results provide a simple explanation for the existence of salt-and-pepper arrangements in rodents and pinwheel arrangements in the visual cortex of primates, carnivores, and ungulates without assuming differences in the general visual cortex architecture and connectivity.

  7. [Progress in activity-dependent structural plasticity of neural circuits in cortex].

    Science.gov (United States)

    Rao, Xiao-Ping; Xu, Zhi-Xiang; Xu, Fu-Qiang

    2012-10-01

    Neural circuits of mammalian cerebral cortex have exhibited amazing abilities of structural and functional plasticity in development, learning and memory, neurological and psychiatric diseases. With the new imaging techniques and the application of molecular biology methods, observation neural circuits' structural dynamics within the cortex in vivo at the cellular and synaptic level was possible, so there were many great progresses in the field of the activity-dependent structural plasticity over the past decade. This paper reviewed some of the aspects of the experimental results, focused on the characteristics of dendritic structural plasticity in individual growth and development, rich environment, sensory deprivation, and pathological conditions, as well as learning and memory, especially the dynamics of dendritic spines on morphology and quantity; after that, we introduced axonal structural plasticity, the molecular and cellular mechanisms of structural plasticity, and proposed some future problems to be solved at last.

  8. Incorporation of iodine into apatite structure: a crystal chemistry approach using Artificial Neural Network

    OpenAIRE

    Jianwei eWang

    2015-01-01

    Materials with apatite crystal structure have a great potential for incorporating the long-lived radioactive iodine isotope (129I) in the form of iodide (I−) from nuclear waste streams. Because of its durability and potentially high iodine content, the apatite waste form can reduce iodine release rate and minimize the waste volume. Crystal structure and composition of apatite (A5(XO4)3Z) was investigated for iodide incorporation into the channel of the structure using Artificial Neural Networ...

  9. Entropy-based generation of supervised neural networks for classification of structured patterns.

    Science.gov (United States)

    Tsai, Hsien-Leing; Lee, Shie-Jue

    2004-03-01

    Sperduti and Starita proposed a new type of neural network which consists of generalized recursive neurons for classification of structures. In this paper, we propose an entropy-based approach for constructing such neural networks for classification of acyclic structured patterns. Given a classification problem, the architecture, i.e., the number of hidden layers and the number of neurons in each hidden layer, and all the values of the link weights associated with the corresponding neural network are automatically determined. Experimental results have shown that the networks constructed by our method can have a better performance, with respect to network size, learning speed, or recognition accuracy, than the networks obtained by other methods.

  10. Rod strain after pedicle subtraction osteotomy

    DEFF Research Database (Denmark)

    Gehrchen, Poul Martin; Hallager, Dennis Winge; Dahl, Benny

    2016-01-01

    Pedicle subtraction osteotomy (PSO) can provide major sagittal correction for adult spinal deformity, sometimes achieving correction greater than 308. Surgeons have reported failure rates up to 30% within 2 years, increasing to 46% after 4 to 5 years (SDC Figure 1, http://links.lww.com/BRS/B87......). Revision following failure is difficult on the patient. PSO has achieved positive outcomes, but when used to correct posture in older patients with spinal deformity and fixed sagittal imbalance, rod breakage often leads to multiple surgical revisions. These complications must be avoided....

  11. Lumbar vertebral pedicles: radiologic anatomy and pathology

    Energy Technology Data Exchange (ETDEWEB)

    Patel, N.P.; Kumar, R.; Kinkhabwala, M.; Wengrover, S.I.

    1988-01-01

    With the advancement of high-resolution computed tomography (CT) scanning the spine has added new knowledge to the various conditions affecting the pedicles. We wish to review the entire spectrum of pedicular lesions: the embryology, normal anatomy, normal variants, pitfalls, congenital anomalies, and pathological conditions are discussed. Different imaging modalities involving CT, isotope bone scanning, and Magnetic Resonance Imaging (MRI) are used to complement plain films of the lumbar spine. This subject review is an excellent source for future reference to lumbar pedicular lesions. 27 references.

  12. Neural bases of recommendations differ according to social network structure.

    Science.gov (United States)

    O'Donnell, Matthew Brook; Bayer, Joseph B; Cascio, Christopher N; Falk, Emily B

    2017-01-01

    Ideas spread across social networks, but not everyone is equally positioned to be a successful recommender. Do individuals with more opportunities to connect otherwise unconnected others-high information brokers-use their brains differently than low information brokers when making recommendations? We test the hypothesis that those with more opportunities for information brokerage may use brain systems implicated in considering the thoughts, perspectives, and mental states of others (i.e. 'mentalizing') more when spreading ideas. We used social network analysis to quantify individuals' opportunities for information brokerage. This served as a predictor of activity within meta-analytically defined neural regions associated with mentalizing (dorsomedial prefrontal cortex, temporal parietal junction, medial prefrontal cortex, /posterior cingulate cortex, middle temporal gyrus) as participants received feedback about peer opinions of mobile game apps. Higher information brokers exhibited more activity in this mentalizing network when receiving divergent peer feedback and updating their recommendation. These data support the idea that those in different network positions may use their brains differently to perform social tasks. Different social network positions might provide more opportunities to engage specific psychological processes. Or those who tend to engage such processes more may place themselves in systematically different network positions. These data highlight the value of integrating levels of analysis, from brain networks to social networks. © The Author (2017). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  13. Classification of crystal structure using a convolutional neural network.

    Science.gov (United States)

    Park, Woon Bae; Chung, Jiyong; Jung, Jaeyoung; Sohn, Keemin; Singh, Satendra Pal; Pyo, Myoungho; Shin, Namsoo; Sohn, Kee-Sun

    2017-07-01

    A deep machine-learning technique based on a convolutional neural network (CNN) is introduced. It has been used for the classification of powder X-ray diffraction (XRD) patterns in terms of crystal system, extinction group and space group. About 150 000 powder XRD patterns were collected and used as input for the CNN with no handcrafted engineering involved, and thereby an appropriate CNN architecture was obtained that allowed determination of the crystal system, extinction group and space group. In sharp contrast with the traditional use of powder XRD pattern analysis, the CNN never treats powder XRD patterns as a deconvoluted and discrete peak position or as intensity data, but instead the XRD patterns are regarded as nothing but a pattern similar to a picture. The CNN interprets features that humans cannot recognize in a powder XRD pattern. As a result, accuracy levels of 81.14, 83.83 and 94.99% were achieved for the space-group, extinction-group and crystal-system classifications, respectively. The well trained CNN was then used for symmetry identification of unknown novel inorganic compounds.

  14. The necessity of connection structures in neural models of variable binding

    NARCIS (Netherlands)

    van der Velde, Frank; van der Velde, Frank; de Kamps, Marc

    2015-01-01

    In his review of neural binding problems, Feldman (Cogn Neurodyn 7:1–11, 2013) addressed two types of models as solutions of (novel) variable binding. The one type uses labels such as phase synchrony of activation. The other (‘connectivity based’) type uses dedicated connections structures to

  15. Vibration Based Damage Assessment of a Civil Engineering Structures using a Neural Networks

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Rytter, A.

    In this paper the possibility of using a Multilayer Perceptron (MLP) network trained with the Backpropagation Algorith as a non-destructive damage assessment technique to locate and quantify a damage in Civil Engineering structures is investigated. Since artificial neural networks are proving...

  16. Delineating Neural Structures of Developmental Human Brains with Diffusion Tensor Imaging

    Directory of Open Access Journals (Sweden)

    Hao Huang

    2010-01-01

    Full Text Available The human brain anatomy is characterized by dramatic structural changes during fetal development. It is extraordinarily complex and yet its origin is a simple tubular structure. Revealing detailed anatomy at different stages of brain development not only aids in understanding this highly ordered process, but also provides clues to detect abnormalities caused by genetic or environmental factors. However, anatomical studies of human brain development during the fetal period are surprisingly scarce and histology-based atlases have become available only recently. Diffusion tensor imaging (DTI measures water diffusion to delineate the underlying neural structures. The high contrasts derived from DTI can be used to establish the brain atlas. With DTI tractography, coherent neural structures, such as white matter tracts, can be three-dimensionally reconstructed. The primary eigenvector of the diffusion tensor can be further explored to characterize microstructures in the cerebral wall of the developmental brains. In this mini-review, the application of DTI in order to reveal the structures of developmental fetal brains has been reviewed in the above-mentioned aspects. The fetal brain DTI provides a unique insight for delineating the neural structures in both macroscopic and microscopic levels. The resultant DTI database will provide structural guidance for the developmental study of human fetal brains in basic neuroscience, and reference standards for diagnostic radiology of premature newborns.

  17. Genetic Architect: Discovering Genomic Structure with Learned Neural Architectures

    OpenAIRE

    Deming, Laura; Targ, Sasha; Sauder, Nate; Almeida, Diogo; Ye, Chun Jimmie

    2016-01-01

    Each human genome is a 3 billion base pair set of encoding instructions. Decoding the genome using deep learning fundamentally differs from most tasks, as we do not know the full structure of the data and therefore cannot design architectures to suit it. As such, architectures that fit the structure of genomics should be learned not prescribed. Here, we develop a novel search algorithm, applicable across domains, that discovers an optimal architecture which simultaneously learns general genom...

  18. Accurate and rapid optical characterization of an anisotropic guided structure based on a neural method.

    Science.gov (United States)

    Robert, Stéphane; Battie, Yann; Jamon, Damien; Royer, Francois

    2007-04-10

    Optimal performances of integrated optical devices are obtained by the use of an accurate and reliable characterization method. The parameters of interest, i.e., optical indices and thickness of the waveguide structure, are calculated from effective indices by means of an inversion procedure. We demonstrate how an artificial neural network can achieve such a process. The artificial neural network used is a multilayer perceptron. The first result concerns a simulated anisotropic waveguide. The accuracy in the determination of optical indices and waveguide thickness is 5 x 10(-5) and 4 nm, respectively. Then an experimental application on a silica-titania thin film is performed. In addition, effective indices are measured by m-lines spectroscopy. Finally, a comparison with a classical optimization algorithm demonstrates the robustness of the neural method.

  19. Explicitly integrating parameter, input, and structure uncertainties into Bayesian Neural Networks for probabilistic hydrologic forecasting

    KAUST Repository

    Zhang, Xuesong

    2011-11-01

    Estimating uncertainty of hydrologic forecasting is valuable to water resources and other relevant decision making processes. Recently, Bayesian Neural Networks (BNNs) have been proved powerful tools for quantifying uncertainty of streamflow forecasting. In this study, we propose a Markov Chain Monte Carlo (MCMC) framework (BNN-PIS) to incorporate the uncertainties associated with parameters, inputs, and structures into BNNs. This framework allows the structure of the neural networks to change by removing or adding connections between neurons and enables scaling of input data by using rainfall multipliers. The results show that the new BNNs outperform BNNs that only consider uncertainties associated with parameters and model structures. Critical evaluation of posterior distribution of neural network weights, number of effective connections, rainfall multipliers, and hyper-parameters shows that the assumptions held in our BNNs are not well supported. Further understanding of characteristics of and interactions among different uncertainty sources is expected to enhance the application of neural networks for uncertainty analysis of hydrologic forecasting. © 2011 Elsevier B.V.

  20. Knowledge base and neural network approach for protein secondary structure prediction.

    Science.gov (United States)

    Patel, Maulika S; Mazumdar, Himanshu S

    2014-11-21

    Protein structure prediction is of great relevance given the abundant genomic and proteomic data generated by the genome sequencing projects. Protein secondary structure prediction is addressed as a sub task in determining the protein tertiary structure and function. In this paper, a novel algorithm, KB-PROSSP-NN, which is a combination of knowledge base and modeling of the exceptions in the knowledge base using neural networks for protein secondary structure prediction (PSSP), is proposed. The knowledge base is derived from a proteomic sequence-structure database and consists of the statistics of association between the 5-residue words and corresponding secondary structure. The predicted results obtained using knowledge base are refined with a Backpropogation neural network algorithm. Neural net models the exceptions of the knowledge base. The Q3 accuracy of 90% and 82% is achieved on the RS126 and CB396 test sets respectively which suggest improvement over existing state of art methods. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Learning Orthographic Structure with Sequential Generative Neural Networks

    Science.gov (United States)

    Testolin, Alberto; Stoianov, Ivilin; Sperduti, Alessandro; Zorzi, Marco

    2016-01-01

    Learning the structure of event sequences is a ubiquitous problem in cognition and particularly in language. One possible solution is to learn a probabilistic generative model of sequences that allows making predictions about upcoming events. Though appealing from a neurobiological standpoint, this approach is typically not pursued in…

  2. Wave transmission at low-crested structures using neural networks

    NARCIS (Netherlands)

    Van Oosten, R.P.; Peixó Marco, J.; Van der Meer, J.W.; Van Gent, M.; Verhagen, H.J.

    2006-01-01

    The European Union funded project DELOS was focused on wave transmission and an extensive database on low-crested rubble mound structures was generated. During DELOS, new empirical wave transmission formulae were derived. These formulae still showed a considerable scatter due to a limited number of

  3. Nilai Rerata Vascular Pedicle Width, Vascular Pedicle-Cardiac Ratio Vascular Pedicle-Thoracic Ratio Orang Dewasa Normal Indonesia Studi di RS dr. Cipto Mangunkusomo

    Directory of Open Access Journals (Sweden)

    Rommy Zunera

    2016-03-01

    Full Text Available Vascular pedicle width (VPW adalah jarak tepi luar vena kava superior ke tepi luar arteri subklavia kiri. Pemeriksaan VPW di foto toraks bersifat non-invasif, cepat dan mudah untuk memprediksi hipervolemia.Penelitian ini bertujuan untuk mengetahui rerata nilai VPW orang dewasa normal Indonesia. VPW diukurdengan dua metode: pertama pengukuran VPW tunggal yang akurasinya terbatas di foto toraks digital karenarelatif tidak dipengaruhi faktor magnifikasi. Metode kedua untuk foto toraks nondigital yaitu pengukuranrasio:vascular pedicle-cardiac ratio (VPCR dan vascular pedicle-thoracic ratio (VPTR. Pengukuran serupadilakukan terhadap  topogram CT scan toraks AP terlentang dan CT scan toraks lalu dibandingkan akurasipengukuran di topogram dengan CT scan  toraks sebagai standar baku. Sampel terdiri atas 104 foto toraksPA subyek normal dan 103 CT scan  toraks subyek terpilih. Pada pemeriksaan toraks PA didapatkan rerata VPW 48,0±5,5mm, rerata VPCR 40,3±4,6%, dan rerata VPTR 17,2±1,7%. Pada pemeriksaan topogram CTscan didapatkan rerata VPW 50,3±6,2mm, rerata VPTR 45±5,1%, dan rerata VPTR 19,8±2,5%. Rerata VPWpada CT scan toraks 50,4±6,1mm. Pengukuran di foto toraks AP 10% lebih besar dibandingkan pada fototoraks PA dan pengukuranVPW di foto toraks terbukti memiliki akurasi  tinggi. Kata kunci: fototoraks, vascular pedicle width, vascular pedicle-cardiac ratio, vascular pedicle-thoracic ratio, hipervolemia.   The Mean Value of Vascular Pedicle Width, Vascular Pedicle-Cardiac Ratio,Vascular Pedicle-Thoracic Ratio of Normal Indonesian Adult Study In dr. Cipto Mangunkusomo Hospital Abstract Vascular pedicle width (VPW is the distance, from a perpendicular line at the takeoff point of the left subclavian artery off the aorta to the point at which the superior vena cava. Measurement of VPW on chestx-ray is relatively non-invasive, fast and easy technique as  hypervolemia predictor. The purpose of thisstudy is to know the mean VPW value of normal

  4. Neural network based semi-active control strategy for structural vibration mitigation with magnetorheological damper

    DEFF Research Database (Denmark)

    Bhowmik, Subrata

    2011-01-01

    This paper presents a neural network based semi-active control method for a rotary type magnetorheological (MR) damper. The characteristics of the MR damper are described by the classic Bouc-Wen model, and the performance of the proposed control method is evaluated in terms of a base exited shear...... frame structure. As demonstrated in the literature effective damping of flexible structures is obtained by a suitable combination of pure friction and negative damper stiffness. This damper model is rate-independent and fully described by the desired shape of the hysteresis loops or force...... mode of the structure. The neural network control is then developed to reproduce the desired force based on damper displacement and velocity as network input, and it is therefore referred to as an amplitude dependent model reference control method. An inverse model of the MR damper is needed...

  5. Neural networkbased semi-active control strategy for structural vibration mitigation with magnetorheological damper

    DEFF Research Database (Denmark)

    Bhowmik, Subrata

    2011-01-01

    This paper presents a neural network based semi-active control method for a rotary type magnetorheological (MR) damper. The characteristics of the MR damper are described by the classic Bouc-Wen model, and the performance of the proposed control method is evaluated in terms of a base exited shear...... frame structure. As demonstrated in the literature effective damping of flexible structures is obtained by a suitable combination of pure friction and negative damper stiffness. This damper model is rate-independent and fully described by the desired shape of the hysteresis loops or force...... mode of the structure. The neural network control is then developed to reproduce the desired force based on damper displacement and velocity as network input, and it is therefore referred to as an amplitude dependent model reference control method. An inverse model of the MR damper is needed...

  6. Training verb argument structure production in agrammatic aphasia: behavioral and neural recovery patterns.

    Science.gov (United States)

    Thompson, Cynthia K; Riley, Ellyn A; den Ouden, Dirk-Bart; Meltzer-Asscher, Aya; Lukic, Sladjana

    2013-10-01

    Neuroimaging and lesion studies indicate a left hemisphere network for verb and verb argument structure processing, involving both frontal and temporoparietal brain regions. Although their verb comprehension is generally unimpaired, it is well known that individuals with agrammatic aphasia often present with verb production deficits, characterized by an argument structure complexity hierarchy, indicating faulty access to argument structure representations for production and integration into syntactic contexts. Recovery of verb processing in agrammatism, however, has received little attention and no studies have examined the neural mechanisms associated with improved verb and argument structure processing. In the present study we trained agrammatic individuals on verbs with complex argument structure in sentence contexts and examined generalization to verbs with less complex argument structure. The neural substrates of improved verb production were examined using functional magnetic resonance imaging (fMRI). Eight individuals with chronic agrammatic aphasia participated in the study (four experimental and four control participants). Production of three-argument verbs in active sentences was trained using a sentence generation task emphasizing the verb's argument structure and the thematic roles of sentential noun phrases. Before and after training, production of trained and untrained verbs was tested in naming and sentence production and fMRI scans were obtained, using an action naming task. Significant pre- to post-training improvement in trained and untrained (one- and two-argument) verbs was found for treated, but not control, participants, with between-group differences found for verb naming, production of verbs in sentences, and production of argument structure. fMRI activation derived from post-treatment compared to pre-treatment scans revealed upregulation in cortical regions implicated for verb and argument structure processing in healthy controls. Training

  7. Verification of the authenticity of handwritten signature using structure neural-network-type OCON

    Science.gov (United States)

    Molina, M. L.; Arias, N. A.; Gualdron, Oscar

    2004-10-01

    A method in order to carry out the verification of handwritten signatures is described. The method keeps in mind global features and local features that encode the shape and the dynamics of the signatures. Signatures are recorded with a digital tablet that can read the position and pressure of the pen. Input patterns are considered time and space dependent. Before extracting the information of the static features such as total length or height/width ratio, and the dynamic features such as speed or acceleration, the signature is normalized for position, size and orientation using its Fourier Descriptors. The comparison stage is carried out for algorithms of neurals networks. For each one of the sets of features a special two stage Perceptron OCON (one-class-one-network) classification structure has been implemented. In the first stage networks multilayer perceptron with few neurons are used. The classifier combines the decision results of the neural networks and the Euclidean distance obtained using the two feature sets. The results of the first-stage classifier feed a second-stage radial basis function (RBF) neural network structure, which makes the final decision. The entire system was extensively tested, 160 neurals networks has been implemented.

  8. Prediction of Henry's law constants by a quantitative structure property relationship and neural networks.

    Science.gov (United States)

    English, N J; Carroll, D G

    2001-01-01

    Multiple linear regression analysis and neural networks were employed to develop predictive models for Henry's law constants (HLCs) for organic compounds of environmental concern in pure water at 25 degrees C, using a set of quantitative structure property relationship (QSPR)-based descriptors to encode various molecular structural features. Two estimation models were developed from a set of 303 compounds using 10 and 12 descriptors, one of these models using two descriptors to account for hydrogen-bonding characteristics explicitly; these were validated subsequently on an external set of 54 compounds. For each model, a linear regression and neural network version was prepared. The standard errors of the linear regression models for the training data set were 0.262 and 0.488 log(H(cc)) units, while those of the neural network analogues were lower at 0.202 and 0.224, respectively; the linear regression models explained 98.3% and 94.3% of the variance in the development data, respectively, the neural network models giving similar quality results of 99% and 98.3%, respectively. The various descriptors used describe connectivity, charge distribution, charged surface area, hydrogen-bonding characteristics, and group influences on HLC values.

  9. Inferring synaptic structure in presence of neural interaction time scales.

    Directory of Open Access Journals (Sweden)

    Cristiano Capone

    Full Text Available Biological networks display a variety of activity patterns reflecting a web of interactions that is complex both in space and time. Yet inference methods have mainly focused on reconstructing, from the network's activity, the spatial structure, by assuming equilibrium conditions or, more recently, a probabilistic dynamics with a single arbitrary time-step. Here we show that, under this latter assumption, the inference procedure fails to reconstruct the synaptic matrix of a network of integrate-and-fire neurons when the chosen time scale of interaction does not closely match the synaptic delay or when no single time scale for the interaction can be identified; such failure, moreover, exposes a distinctive bias of the inference method that can lead to infer as inhibitory the excitatory synapses with interaction time scales longer than the model's time-step. We therefore introduce a new two-step method, that first infers through cross-correlation profiles the delay-structure of the network and then reconstructs the synaptic matrix, and successfully test it on networks with different topologies and in different activity regimes. Although step one is able to accurately recover the delay-structure of the network, thus getting rid of any a priori guess about the time scales of the interaction, the inference method introduces nonetheless an arbitrary time scale, the time-bin dt used to binarize the spike trains. We therefore analytically and numerically study how the choice of dt affects the inference in our network model, finding that the relationship between the inferred couplings and the real synaptic efficacies, albeit being quadratic in both cases, depends critically on dt for the excitatory synapses only, whilst being basically independent of it for the inhibitory ones.

  10. Optimizing the De-Noise Neural Network Model for GPS Time-Series Monitoring of Structures

    Directory of Open Access Journals (Sweden)

    Mosbeh R. Kaloop

    2015-09-01

    Full Text Available The Global Positioning System (GPS is recently used widely in structures and other applications. Notwithstanding, the GPS accuracy still suffers from the errors afflicting the measurements, particularly the short-period displacement of structural components. Previously, the multi filter method is utilized to remove the displacement errors. This paper aims at using a novel application for the neural network prediction models to improve the GPS monitoring time series data. Four prediction models for the learning algorithms are applied and used with neural network solutions: back-propagation, Cascade-forward back-propagation, adaptive filter and extended Kalman filter, to estimate which model can be recommended. The noise simulation and bridge’s short-period GPS of the monitoring displacement component of one Hz sampling frequency are used to validate the four models and the previous method. The results show that the Adaptive neural networks filter is suggested for de-noising the observations, specifically for the GPS displacement components of structures. Also, this model is expected to have significant influence on the design of structures in the low frequency responses and measurements’ contents.

  11. Omental pedicle transposition and suture repair of peripheral nerve ...

    African Journals Online (AJOL)

    Abu wael

    histological, morphometric criteria and relative gastrocnemius muscle weight. The results of the examination show that the treated group had better regeneration and functional recovery. Key words: Omental pedicle, regeneration, hispathological, morphometric, sciatic nerve. INTRODUCTION. The peripheral nervous system ...

  12. Lumbar pedicle screw placement: Using only AP plane imaging

    Directory of Open Access Journals (Sweden)

    Anil Sethi

    2012-01-01

    Conclusion: Placement of pedicle screws under fluoroscopic guidance using AP plane imaging alone with tactile guidance is safe, fast, and reliable. However, a good understanding of the radiographic landmarks is a prerequisite.

  13. Tai Chi pedicle screw placement for severe scoliosis.

    Science.gov (United States)

    Chang, Kao-Wha; Wang, Yu-Fei; Zhang, Guo-Zhi; Cheng, Ching-Wei; Chen, Hung-Yi; Leng, Xiangyang; Chen, Yin-Yu

    2012-05-01

    Retrospective. To evaluate the clinical safety and accuracy of the Tai Chi ((Equation is included in full-text article.)) technique for placing pedicle screws, without intraoperative radiographic imaging, in severe scoliotic spines. The current techniques for pedicle screw placement have a number of drawbacks in cases of severe scoliosis, including difficulty or impossibility to use, delayed operative time, requiring the presence of trained personnel for the duration of the surgery, high cost issues, increased radiation exposure, and technical challenges. No previous report has described the application of the Tai Chi pedicle screw placement technique for severe scoliosis. Between 2006 and 2008, the cases of 39 consecutive patients with severe scoliosis (Cobb angle >100 degrees) who underwent posterior correction and stabilization (from T1 to L5) using 992 transpedicular screws were examined. The mean patient age was 25.7 (range, 11 to 63) years at the time of surgery. Pedicle screws were inserted by the Tai Chi technique using anatomic landmarks and preoperative radiographs as a guide. Tai Chi drilling fully utilizes the natural anatomic and physical characteristics of pedicles and unconstrained circular force. By nature, a drill bit driven by unconstrained circular force would migrate within the pedicle along a path of least resistance, advancing along the central cancellous bone tunnel spontaneously. Accurate drilling was achieved by following the nature and sticking to the hand sensation when the drill bit broke through the cancellous bone. The total time for inserting all pedicle screws in each case was recorded. Postoperative computed tomography scans were performed to evaluate the position of the inserted pedicle screws. The screw position was classified as "in" or "out." The distance of perforation was measured. The average Cobb angle was 127 degrees (range, 100 to 153 degrees). The number of screws inserted at each level were as follows: T1 (n=10), T2 (n

  14. Facet violation with the placement of percutaneous pedicle screws.

    Science.gov (United States)

    Patel, Rakesh D; Graziano, Gregory P; Vanderhave, Kelly L; Patel, Alpesh A; Gerling, Michael C

    2011-12-15

    Independent review and classification of therapeutic procedures performed on cadavers by surgeons blinded to purpose of study. The objective of this study is to determine the rate of facet violation with the placement of percutaneous pedicle screws. Improvements in percutaneous instrumentation and fluoroscopic imaging have led to a resurgence of percutaneous pedicle screw insertion in lumbar spine surgery in an attempt to minimize many of the complications associated with open techniques of pedicle screw placement. Rates of pedicle breech and neurologic injury resulting from percutaneous insertion are reportedly similar to those of open techniques. Postoperative pain because of impingement and instability is believed to result from violation of the facet capsule or facet joint. To the authors' knowledge, however, the rate of facet injury associated with the placement of percutaneous pedicle screws is unreported in the literature. Percutaneous pedicle screw placement was performed on 4 cadaveric specimens by 4 certified orthopedic surgeons who had clinical experience in the procedure and who were blinded to the study's purpose. The surgeons were instructed to place pedicle screws from L1-S1 using their preferred clinical techniques and a 5.5-mm screw system with which they were all familiar. All surgeons utilized 1 OEC C-arm for fluoroscopic imaging. After insertion, 2 independent spine surgeons each reviewed and classified the placement of all facet screws. A total of 48 screws were inserted and classified. The placement of 28 screws (58%) resulted in violation of facet articulation, with 8 of these screws being intra-articular. Interobserver reliability of the classification system was 100%. Percutaneous pedicle screw placement may result in a high rate of facet violation. Facet injury can be reliability classified and therefore, perhaps, easily prevented.

  15. Prediction of Optimal Design and Deflection of Space Structures Using Neural Networks

    Directory of Open Access Journals (Sweden)

    Reza Kamyab Moghadas

    2012-01-01

    Full Text Available The main aim of the present work is to determine the optimal design and maximum deflection of double layer grids spending low computational cost using neural networks. The design variables of the optimization problem are cross-sectional area of the elements as well as the length of the span and height of the structures. In this paper, a number of double layer grids with various random values of length and height are selected and optimized by simultaneous perturbation stochastic approximation algorithm. Then, radial basis function (RBF and generalized regression (GR neural networks are trained to predict the optimal design and maximum deflection of the structures. The numerical results demonstrate the efficiency of the proposed methodology.

  16. Evolution in the treatment of sinonasal inverted papilloma: pedicle-oriented endoscopic surgery.

    Science.gov (United States)

    Pagella, Fabio; Pusateri, Alessandro; Giourgos, Georgios; Tinelli, Carmine; Matti, Elina

    2014-01-01

    In the literature, the global endoscopic sinus surgery (ESS) success in the treatment of sinonasal inverted papilloma (IP) is 95%. This study was designed to describe a conservative endoscopic approach, based on research of the tumor's pedicle and treatment concentrated on its site of attachment, and to compare the results of this technique with the outcome of standard endoscopic treatment. Retrospective analysis of the patients treated in our institution for paranasal inverted papilloma (IP), between 2002 and 2011 with a minimum of 18 months follow-up was performed. Group A received a standard ESS including whole sinus demucosization (maxillary, ethmoid, frontal, or sphenoid sinus) and bony wall drilling. Group B patients instead underwent pedicle-oriented endoscopic surgery (POES); in this group, bony demucosization and drilling were selectively conducted around the site of pedicle attachment of the tumor. The cohort included 73 patients (median age, 60.5 years; median follow-up, 58 months). Group A/group B consisted of 37/36 patients. IP persistence-recurrence for group A/group B was 0/1 cases. Oncological success for global endoscopic/group A/group B was 98.6% (72/73)/100% (37/37)/97.2% (35/36). We noticed a significant difference in surgical operative time and postoperative complication rate among the groups, in favor of POES technique. Our data confirm the efficacy of the endonasal endoscopic treatment for sinonasal IP. Moreover, the even more conservative endoscopic treatment proposed (POES) seems to offer good control of the disease, shorter operating times, avoidance of unnecessary surgery with respect to uninvolved structures, and permits a follow-up aimed at the site of the pedicle attachment.

  17. The neural origins of shell structure and pattern in aquatic mollusks.

    Science.gov (United States)

    Boettiger, Alistair; Ermentrout, Bard; Oster, George

    2009-04-21

    We present a model to explain how the neurosecretory system of aquatic mollusks generates their diversity of shell structures and pigmentation patterns. The anatomical and physiological basis of this model sets it apart from other models used to explain shape and pattern. The model reproduces most known shell shapes and patterns and accurately predicts how the pattern alters in response to environmental disruption and subsequent repair. Finally, we connect the model to a larger class of neural models.

  18. The superior pedicle mammaplasty for the treatment of pedunculous breast.

    Science.gov (United States)

    Papalia, Igor; d'Alcontres, Francesco Stagno; Colonna, Michele Rosario; Mojallal, Ali M; Foyatier, Jean-Louis

    2007-01-01

    The superior pedicle mammaplasty is a technique frequently employed in the treatment of breast ptosis, associated or not with hypertrophy of the gland, followed by satisfactory results. This technique is normally not indicated in severe breast ptosis (pendulous breast) because of the excessive length of the pedicle supplying nipple-areola-complex (NAC), with the risk of ischemia. In these cases the standard technique is the free-nipple-graft mammaplasty. However, the deepen knowledge about vascular anatomy of the breast and the aptitude to perform superior pedicle mammaplasty, induced the authors to indicate this technique even in these cases improving the aesthetic and functional outcomes. The authors present a series of 30 patient with pendulous breasts, with sternal notch-nipple distance equal or superior to 32 cm (45 cm maximum; mean value 35.1), treated with the superior pedicle mammaplasty with inverted "T" scar. The results confirm the reliability of superior pedicle for the nipple-areolar complex blood supply, associated with satisfactory aesthetic results due especially to the good breast projection. They conclude that superior pedicle technique mammaplasty, even if normally not indicated in these cases, is instead suitable for the treatment of pendulous breasts with great sternal notch-nipple distance, permitting to take advantages of this technique.

  19. Deep neural nets as a method for quantitative structure-activity relationships.

    Science.gov (United States)

    Ma, Junshui; Sheridan, Robert P; Liaw, Andy; Dahl, George E; Svetnik, Vladimir

    2015-02-23

    Neural networks were widely used for quantitative structure-activity relationships (QSAR) in the 1990s. Because of various practical issues (e.g., slow on large problems, difficult to train, prone to overfitting, etc.), they were superseded by more robust methods like support vector machine (SVM) and random forest (RF), which arose in the early 2000s. The last 10 years has witnessed a revival of neural networks in the machine learning community thanks to new methods for preventing overfitting, more efficient training algorithms, and advancements in computer hardware. In particular, deep neural nets (DNNs), i.e. neural nets with more than one hidden layer, have found great successes in many applications, such as computer vision and natural language processing. Here we show that DNNs can routinely make better prospective predictions than RF on a set of large diverse QSAR data sets that are taken from Merck's drug discovery effort. The number of adjustable parameters needed for DNNs is fairly large, but our results show that it is not necessary to optimize them for individual data sets, and a single set of recommended parameters can achieve better performance than RF for most of the data sets we studied. The usefulness of the parameters is demonstrated on additional data sets not used in the calibration. Although training DNNs is still computationally intensive, using graphical processing units (GPUs) can make this issue manageable.

  20. A New Training Method for Analyzable Structured Neural Network and Application of Daily Peak Load Forecasting

    Science.gov (United States)

    Iizaka, Tatsuya; Matsui, Tetsuro; Fukuyama, Yoshikazu

    This paper presents a daily peak load forecasting method using an analyzable structured neural network (ASNN) in order to explain forecasting reasons. In this paper, we propose a new training method for ASNN in order to explain forecasting reason more properly than the conventional training method. ASNN consists of two types of hidden units. One type of hidden units has connecting weights between the hidden units and only one group of related input units. Another one has connecting weights between the hidden units and all input units. The former type of hidden units allows to explain forecasting reasons. The latter type of hidden units ensures the forecasting performance. The proposed training method make the former type of hidden units train only independent relations between the input factors and output, and make the latter type of hidden units train only complicated interactions between input factors. The effectiveness of the proposed neural network is shown using actual daily peak load. ASNN trained by the proposed method can explain forecasting reasons more properly than ASNN trained by the conventional method. Moreover, the proposed neural network can forecast daily peak load more accurately than conventional neural network trained by the back propagation algorithm.

  1. [Clinical application of atlantoaxial pedicle screw internal fixation for treatment of atlantoaxial dislocation].

    Science.gov (United States)

    Yang, Yong-Jun; Zhang, En-Zhong; Tan, Yuan-Chao; Zhou, Ji-Ping; Yao, Shu-Qiang; Jiang, Chuan-Jie; Cong, Pei-Yan

    2009-11-01

    To investigate the clinical effect of atlantoaxial pedicle screw internal fixation for treatment of atlantoaxial dislocation. Sixteen patients with atlantoaxial dislocation were treated from Dec. 2005 to June 2007, included 10 males and 6 females, aged from 38 to 45 years old (means 40.5 years). Among them 12 patients combined with nerve injury, according to ASIA grade: there were 3 cases in grade B, 5 cases in grade C, 4 cases in grade D. All patients received preoperative CT, radiograph and skull traction. Intraoperative posterior approach general spine pedicle screw-rod orthopaedics fixation system used and iliac bone block were implanted in space of posterior atlantal arch and axial vertebral plate. The outcome and complications were observed in the near future. There was no vascular or neural injury found. The patients were followed up for 12 to 24 months (means 18 months). All head pain, acid storm symptoms were improved after operation. According to the Odom's clinical efficacy evaluation standard, 12 cases were excellent, 4 were good. Eleven cases of 12 with nerve injury recovered significantly. By ASIA classification: 1 cases was in grade B, 2 cases were in grade C, 5 cases were in grade D, 4 cases were in grade E. No looseness or breakage of screw occurred. Bony fusion was achieved in all cases. Posterior approach atlantoaxial pedicle screw internal fixation have the advantages of direct screw placement, short-segment fusion, intraoperative reduction, fixation reliable, high fusion rate, and it can restablish the upper cervical vertebrae stability and help to recover the spinal cord and nerve function.

  2. Computed tomography-based morphometric analysis of cervical pedicles in Indian population: A pilot study to assess feasibility of transpedicular screw fixation

    Directory of Open Access Journals (Sweden)

    A R Patwardhan

    2012-01-01

    Full Text Available Background: Cervical transpedicular screw fixation is safe and is probably going to be the gold standard for cervical spine fixation. However, cervical transpedicular screw use in the Asian population can be limited as the transverse diameter in this group of patients may not be adequate to accommodate the 3.5-mm pedicular screw thus injuring the vital structures located in the close proximity of the pedicles. Thus lateral mass fixation remains the mainstay of treatment. The present study evaluated the transverse cervical pedicle diameter of C2-C7 vertebrae in a pilot study in 27 Indian subjects using computed tomography (CT imaging and evaluated the feasibility of transpedicular screw fixation in them. Aims: To evaluate the feasibility of transpedicular screw fixation in the Indian population. Settings and Design: The cervical pedicle diameter size differs between the Asian and non-Asian population. The authors studied the transverse pedicle diameter of the C2-C7 of the cervical spine in the Indian population using CT measurements. This cross-sectional study was carried out at a tertiary care centre for a period of four months from October 2010 to December 2010. Material and Methods: Measurements of cervical pedicles in the subjects were performed on the CT workstation from the CT images taken at 2.5-mm interval. The transverse pedicle diameter was defined as the outermost diameter of the pedicle, taken perpendicular to the axis of the pedicle at the narrowest point and measured in millimeters±0.1 mm. Statistical Analysis: Descriptive statistics was used to represent percentage of transverse diameter of cervical pedicles less than 5 mm in male and female subjects at C2-C7 levels. Since there is no previous study done in India, we initiated the study with sample size of 27 as a pilot study. The statistical analysis was performed using SPSS software. Results: The mean transverse diameters of the cervical pedicles of C2, C3, C4, C5, C6 and C7 in

  3. Flexible deep brain neural probes based on a parylene tube structure

    Science.gov (United States)

    Zhao, Zhiguo; Kim, Eric; Luo, Hao; Zhang, Jinsheng; Xu, Yong

    2018-01-01

    Most microfabricated neural probes have limited shank length, which prevents them from reaching many deep brain structures. This paper reports deep brain neural probes with ultra-long penetrating shanks based on a simple but novel parylene tube structure. The mechanical strength of the parylene tube shank is temporarily enhanced during implantation by inserting a metal wire. The metal wire can be removed after implantation, making the implanted probe very flexible and thus minimizing the stress caused by micromotions of brain tissues. Optogenetic stimulation and chemical delivery capabilities can be potentially integrated by taking advantage of the tube structure. Single-shank prototypes with a shank length of 18.2 mm have been developed. The microfabrication process comprises of deep reactive ion etching (DRIE) of silicon, parylene conformal coating/refilling, and XeF2 isotropic silicon etching. In addition to bench-top insertion characterization, the functionality of developed probes has been preliminarily demonstrated by implanting into the amygdala of a rat and recording neural signals.

  4. Neural circuit remodeling and structural plasticity in the cortex during chronic pain.

    Science.gov (United States)

    Kim, Woojin; Kim, Sun Kwang

    2016-01-01

    Damage in the periphery or spinal cord induces maladaptive plastic changes along the somatosensory nervous system from the periphery to the cortex, often leading to chronic pain. Although the role of neural circuit remodeling and structural synaptic plasticity in the 'pain matrix' cortices in chronic pain has been thought as a secondary epiphenomenon to altered nociceptive signaling in the spinal cord, progress in whole brain imaging studies on human patients and animal models has suggested a possibility that plastic changes in cortical neural circuits may actively contribute to chronic pain symptoms. Furthermore, recent development in two-photon microscopy and fluorescence labeling techniques have enabled us to longitudinally trace the structural and functional changes in local circuits, single neurons and even individual synapses in the brain of living animals. These technical advances has started to reveal that cortical structural remodeling following tissue or nerve damage could rapidly occur within days, which are temporally correlated with functional plasticity of cortical circuits as well as the development and maintenance of chronic pain behavior, thereby modifying the previous concept that it takes much longer periods (e.g. months or years). In this review, we discuss the relation of neural circuit plasticity in the 'pain matrix' cortices, such as the anterior cingulate cortex, prefrontal cortex and primary somatosensory cortex, with chronic pain. We also introduce how to apply long-term in vivo two-photon imaging approaches for the study of pathophysiological mechanisms of chronic pain.

  5. Real-Time Structural Damage Assessment Using Artificial Neural Networks and Antiresonant Frequencies

    Directory of Open Access Journals (Sweden)

    V. Meruane

    2014-01-01

    Full Text Available The main problem in damage assessment is the determination of how to ascertain the presence, location, and severity of structural damage given the structure's dynamic characteristics. The most successful applications of vibration-based damage assessment are model updating methods based on global optimization algorithms. However, these algorithms run quite slowly, and the damage assessment process is achieved via a costly and time-consuming inverse process, which presents an obstacle for real-time health monitoring applications. Artificial neural networks (ANN have recently been introduced as an alternative to model updating methods. Once a neural network has been properly trained, it can potentially detect, locate, and quantify structural damage in a short period of time and can therefore be applied for real-time damage assessment. The primary contribution of this research is the development of a real-time damage assessment algorithm using ANN and antiresonant frequencies. Antiresonant frequencies can be identified more easily and more accurately than mode shapes, and they provide the same information. This research addresses the setup of the neural network parameters and provides guidelines for the selection of these parameters in similar damage assessment problems. Two experimental cases validate this approach: an 8-DOF mass-spring system and a beam with multiple damage scenarios.

  6. Musical intervention enhances infants' neural processing of temporal structure in music and speech.

    Science.gov (United States)

    Zhao, T Christina; Kuhl, Patricia K

    2016-05-10

    Individuals with music training in early childhood show enhanced processing of musical sounds, an effect that generalizes to speech processing. However, the conclusions drawn from previous studies are limited due to the possible confounds of predisposition and other factors affecting musicians and nonmusicians. We used a randomized design to test the effects of a laboratory-controlled music intervention on young infants' neural processing of music and speech. Nine-month-old infants were randomly assigned to music (intervention) or play (control) activities for 12 sessions. The intervention targeted temporal structure learning using triple meter in music (e.g., waltz), which is difficult for infants, and it incorporated key characteristics of typical infant music classes to maximize learning (e.g., multimodal, social, and repetitive experiences). Controls had similar multimodal, social, repetitive play, but without music. Upon completion, infants' neural processing of temporal structure was tested in both music (tones in triple meter) and speech (foreign syllable structure). Infants' neural processing was quantified by the mismatch response (MMR) measured with a traditional oddball paradigm using magnetoencephalography (MEG). The intervention group exhibited significantly larger MMRs in response to music temporal structure violations in both auditory and prefrontal cortical regions. Identical results were obtained for temporal structure changes in speech. The intervention thus enhanced temporal structure processing not only in music, but also in speech, at 9 mo of age. We argue that the intervention enhanced infants' ability to extract temporal structure information and to predict future events in time, a skill affecting both music and speech processing.

  7. Musical intervention enhances infants’ neural processing of temporal structure in music and speech

    Science.gov (United States)

    Zhao, T. Christina; Kuhl, Patricia K.

    2016-01-01

    Individuals with music training in early childhood show enhanced processing of musical sounds, an effect that generalizes to speech processing. However, the conclusions drawn from previous studies are limited due to the possible confounds of predisposition and other factors affecting musicians and nonmusicians. We used a randomized design to test the effects of a laboratory-controlled music intervention on young infants’ neural processing of music and speech. Nine-month-old infants were randomly assigned to music (intervention) or play (control) activities for 12 sessions. The intervention targeted temporal structure learning using triple meter in music (e.g., waltz), which is difficult for infants, and it incorporated key characteristics of typical infant music classes to maximize learning (e.g., multimodal, social, and repetitive experiences). Controls had similar multimodal, social, repetitive play, but without music. Upon completion, infants’ neural processing of temporal structure was tested in both music (tones in triple meter) and speech (foreign syllable structure). Infants’ neural processing was quantified by the mismatch response (MMR) measured with a traditional oddball paradigm using magnetoencephalography (MEG). The intervention group exhibited significantly larger MMRs in response to music temporal structure violations in both auditory and prefrontal cortical regions. Identical results were obtained for temporal structure changes in speech. The intervention thus enhanced temporal structure processing not only in music, but also in speech, at 9 mo of age. We argue that the intervention enhanced infants’ ability to extract temporal structure information and to predict future events in time, a skill affecting both music and speech processing. PMID:27114512

  8. A Feedback Model of Attention Explains the Diverse Effects of Attention on Neural Firing Rates and Receptive Field Structure

    National Research Council Canada - National Science Library

    Miconi, Thomas; VanRullen, Rufin

    2016-01-01

    Visual attention has many effects on neural responses, producing complex changes in firing rates, as well as modifying the structure and size of receptive fields, both in topological and feature space...

  9. Artificial neural networks aided conceptual stage design of water harvesting structures

    Directory of Open Access Journals (Sweden)

    Vinay Chandwani

    2016-09-01

    Full Text Available The paper presents artificial neural networks (ANNs based methodology for ascertaining the structural parameters of water harvesting structures (WHS at the conceptual stage of design. The ANN is trained using exemplar patterns generated using an in-house MSExcel based design program, to draw a functional relationship between the five inputs design parameters namely, peak flood discharge, safe bearing capacity of strata, length of structure, height of structure and silt factor and four outputs namely, top width, bottom width, foundation depth and flood lift representing the structural parameters of WHS. The results of the study show that, the structural parameters of the WHS predicted using ANN model are in close agreement with the actual field parameters. The versatility of ANN to map complex or complex unknown relationships has been proven in the study. A parametric sensitivity study is also performed to assess the most significant design parameter. The study holistically presents a neural network based decision support tool that can be used to accurately estimate the major design parameters of the WHS at the conceptual stage of design in quick time, aiding the engineer-in-charge to conveniently forecast the budget requirements and minimize the labor involved during the subsequent phases of analysis and design.

  10. Structural Damage Identification Based on Rough Sets and Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Chengyin Liu

    2014-01-01

    Full Text Available This paper investigates potential applications of the rough sets (RS theory and artificial neural network (ANN method on structural damage detection. An information entropy based discretization algorithm in RS is applied for dimension reduction of the original damage database obtained from finite element analysis (FEA. The proposed approach is tested with a 14-bay steel truss model for structural damage detection. The experimental results show that the damage features can be extracted efficiently from the combined utilization of RS and ANN methods even the volume of measurement data is enormous and with uncertainties.

  11. Elements of an algorithm for optimizing a parameter-structural neural network

    Directory of Open Access Journals (Sweden)

    Mrówczyńska Maria

    2016-06-01

    Full Text Available The field of processing information provided by measurement results is one of the most important components of geodetic technologies. The dynamic development of this field improves classic algorithms for numerical calculations in the aspect of analytical solutions that are difficult to achieve. Algorithms based on artificial intelligence in the form of artificial neural networks, including the topology of connections between neurons have become an important instrument connected to the problem of processing and modelling processes. This concept results from the integration of neural networks and parameter optimization methods and makes it possible to avoid the necessity to arbitrarily define the structure of a network. This kind of extension of the training process is exemplified by the algorithm called the Group Method of Data Handling (GMDH, which belongs to the class of evolutionary algorithms. The article presents a GMDH type network, used for modelling deformations of the geometrical axis of a steel chimney during its operation.

  12. Task-dependent neural and behavioral effects of verb argument structure features.

    Science.gov (United States)

    Malyutina, Svetlana; den Ouden, Dirk-Bart

    2017-05-01

    Understanding which verb argument structure (VAS) features (if any) are part of verbs' lexical entries and under which conditions they are accessed provides information on the nature of lexical representations and sentence construction. We investigated neural and behavioral effects of three understudied VAS characteristics (number of subcategorization options, number of thematic options and overall number of valency frames) in lexical decision and sentence well-formedness judgment in healthy adults. VAS effects showed strong dependency on processing conditions. As reflected by behavioral performance and neural recruitment patterns, increased VAS complexity in terms of subcategorization options and thematic options had a detrimental effect on sentence processing, but facilitated lexical access to single words, possibly by providing more lexico-semantic associations and access routes (facilitation through complexity). Effects of the number of valency frames are equivocal. We suggest that VAS effects may be mediated semantically rather than by a dedicated VAS module in verbs' representations. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. New means in spinal pedicle hook fixation. A biomechanical evaluation.

    Science.gov (United States)

    Berlemann, U; Cripton, P; Nolte, L P; Lippuner, K; Schläpfer, F

    1995-01-01

    Pedicle hooks which are used as an anchorage for posterior spinal instrumentation may be subjected to considerable three-dimensional forces. In order to achieve stronger attachment to the implantation site, hooks using screws for additional fixation have been developed. The failure loads and mechanisms of three such devices have been experimentally determined on human thoracic vertebrae: the Universal Spine System (USS) pedicle hook with one screw, a prototype pedicle hook with two screws and the Cotrel-Dubousset (CD) pedicle hook with screw. The USS hooks use 3.2-mm self-tapping fixation screws which pass into the pedicle, whereas the CD hook is stabilised with a 3-mm set screw pressing against the superior part of the facet joint. A clinically established 5-mm pedicle screw was tested for comparison. A matched pair experimental design was implemented to evaluate these implants in constrained (series I) and rotationally unconstrained (series II) posterior pull-out tests. In the constrained tests the pedicle screw was the strongest implant, with an average pull-out force of 1650 N (SD 623 N). The prototype hook was comparable, with an average failure load of 1530 N (SD 414 N). The average pull-out force of the USS hook with one screw was 910 N (SD 243 N), not significantly different to the CD hook's average failure load of 740 N (SD 189 N). The result of the unconstrained tests were similar, with the prototype hook being the strongest device (average 1617 N, SD 652 N). However, in this series the difference in failure load between the USS hook with one screw and the CD hook was significant. Average failure loads of 792 N (SD 184 N) for the USS hook and 464 N (SD 279 N) for the CD hook were measured. A pedicular fracture in the plane of the fixation screw was the most common failure mode for USS hooks.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Comparison of multiple linear regression and artificial neural network in developing the objective functions of the orthopaedic screws.

    Science.gov (United States)

    Hsu, Ching-Chi; Lin, Jinn; Chao, Ching-Kong

    2011-12-01

    Optimizing the orthopaedic screws can greatly improve their biomechanical performances. However, a methodical design optimization approach requires a long time to search the best design. Thus, the surrogate objective functions of the orthopaedic screws should be accurately developed. To our knowledge, there is no study to evaluate the strengths and limitations of the surrogate methods in developing the objective functions of the orthopaedic screws. Three-dimensional finite element models for both the tibial locking screws and the spinal pedicle screws were constructed and analyzed. Then, the learning data were prepared according to the arrangement of the Taguchi orthogonal array, and the verification data were selected with use of a randomized selection. Finally, the surrogate objective functions were developed by using either the multiple linear regression or the artificial neural network. The applicability and accuracy of those surrogate methods were evaluated and discussed. The multiple linear regression method could successfully construct the objective function of the tibial locking screws, but it failed to develop the objective function of the spinal pedicle screws. The artificial neural network method showed a greater capacity of prediction in developing the objective functions for the tibial locking screws and the spinal pedicle screws than the multiple linear regression method. The artificial neural network method may be a useful option for developing the objective functions of the orthopaedic screws with a greater structural complexity. The surrogate objective functions of the orthopaedic screws could effectively decrease the time and effort required for the design optimization process. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  15. Parafusos pediculares: estruturas anatômicas em risco no tratamento da escoliose idiopática Tornillos pediculares: las estructuras anatómicas en riesgo en el tratamiento de escoliosis idiopática Pedicle screws: anatomic structures at risk in idiopathic scoliosis treatment

    Directory of Open Access Journals (Sweden)

    Herton Rodrigo Tavares Costa

    2012-12-01

    Full Text Available OBJETIVO: Avaliar a posição das estruturas anatômicas em risco durante a inserção de parafusos pediculares na coluna torácica e sua relação com a variação do ângulo de Cobb. MÉTODOS: Os parâmetros estudados foram: a medida do ângulo de Cobb nas radiografias e a posição da medula espinhal, da cavidade pleural e aorta na ressonância nuclear magnética em relação a uma linha de 40mm criada para simular o parafuso pedicular nas cinco vértebras apicais. RESULTADOS: A distância da aorta ao corpo vertebral e o ângulo de segurança do lado convexo apresentaram diferença estatística quando relacionados com a variação do ângulo de Cobb medido. CONCLUSÃO: Os resultados apresentados sugerem maior risco de lesão da artéria aorta com o aumento do ângulo de Cobb e aumento do risco na inserção de parafusos pediculares no lado convexo da curvatura, quando se considera o ângulo de segurança.OBJETIVO: Evaluar la posición de las estructuras anatómicas en situación de riesgo durante la inserción de tornillos pediculares en la columna torácica y su relación con la variación del ángulo de Cobb. MÉTODOS: Los parámetros estudiados fueron: la medida del ángulo de Cobb en las radiografías y la posición de la médula espinal, la cavidad pleural y la aorta en la RM en relación con una línea de 40mm, diseñada para simular el tornillo pedicular en el plano de las cinco vértebras apicales. RESULTADOS: La distancia desde la aorta hacia el cuerpo vertebral y el ángulo de seguridad en el lado convexo mostraron diferencia estadística relacionada con la variación del ángulo de Cobb medido. CONCLUSIÓN: Los resultados sugieren un mayor riesgo de daño a la aorta con el aumento del ángulo de Cobb e incremento del riesgo en la inserción de tornillos pediculares en el lado convexo cuando se considera el ángulo de seguridad.OBJECTIVE: To evaluate the position of anatomical structures at risk during insertion of pedicle screws in

  16. Neural systems supporting linguistic structure, linguistic experience, and symbolic communication in sign language and gesture.

    Science.gov (United States)

    Newman, Aaron J; Supalla, Ted; Fernandez, Nina; Newport, Elissa L; Bavelier, Daphne

    2015-09-15

    Sign languages used by deaf communities around the world possess the same structural and organizational properties as spoken languages: In particular, they are richly expressive and also tightly grammatically constrained. They therefore offer the opportunity to investigate the extent to which the neural organization for language is modality independent, as well as to identify ways in which modality influences this organization. The fact that sign languages share the visual-manual modality with a nonlinguistic symbolic communicative system-gesture-further allows us to investigate where the boundaries lie between language and symbolic communication more generally. In the present study, we had three goals: to investigate the neural processing of linguistic structure in American Sign Language (using verbs of motion classifier constructions, which may lie at the boundary between language and gesture); to determine whether we could dissociate the brain systems involved in deriving meaning from symbolic communication (including both language and gesture) from those specifically engaged by linguistically structured content (sign language); and to assess whether sign language experience influences the neural systems used for understanding nonlinguistic gesture. The results demonstrated that even sign language constructions that appear on the surface to be similar to gesture are processed within the left-lateralized frontal-temporal network used for spoken languages-supporting claims that these constructions are linguistically structured. Moreover, although nonsigners engage regions involved in human action perception to process communicative, symbolic gestures, signers instead engage parts of the language-processing network-demonstrating an influence of experience on the perception of nonlinguistic stimuli.

  17. Applications of Artificial Neural Networks in Structural Engineering with Emphasis on Continuum Models

    Science.gov (United States)

    Kapania, Rakesh K.; Liu, Youhua

    1998-01-01

    The use of continuum models for the analysis of discrete built-up complex aerospace structures is an attractive idea especially at the conceptual and preliminary design stages. But the diversity of available continuum models and hard-to-use qualities of these models have prevented them from finding wide applications. In this regard, Artificial Neural Networks (ANN or NN) may have a great potential as these networks are universal approximators that can realize any continuous mapping, and can provide general mechanisms for building models from data whose input-output relationship can be highly nonlinear. The ultimate aim of the present work is to be able to build high fidelity continuum models for complex aerospace structures using the ANN. As a first step, the concepts and features of ANN are familiarized through the MATLAB NN Toolbox by simulating some representative mapping examples, including some problems in structural engineering. Then some further aspects and lessons learned about the NN training are discussed, including the performances of Feed-Forward and Radial Basis Function NN when dealing with noise-polluted data and the technique of cross-validation. Finally, as an example of using NN in continuum models, a lattice structure with repeating cells is represented by a continuum beam whose properties are provided by neural networks.

  18. Cervical pedicle screw placement: feasibility and accuracy of two new insertion techniques based on morphometric data

    National Research Council Canada - National Science Library

    Reinhold, M; Magerl, F; Rieger, M; Blauth, M

    2007-01-01

    This morphometric and experimental study was designed to assess the dimensions and axes of the subaxial cervical pedicles and to compare the accuracy of two different techniques for subaxial cervical pedicle screw (CPS...

  19. Cervical Fusion for Absent Pedicle Syndrome Manifesting with Myelopathy.

    Science.gov (United States)

    Goodwin, C Rory; Desai, Atman; Khattab, Mohamed H; Elder, Benjamin D; Bydon, Ali; Wolinsky, Jean-Paul

    2016-02-01

    Absent congenital pedicle syndrome is a posterior arch defect characterized by numerous congenital and mechanical abnormalities that result from disconnection of the anterior and posterior columns of the spinal canal. Absent congenital pedicle syndrome is a rare anomaly that is most commonly diagnosed incidentally, after evaluation of minor trauma, or after complaints of chronic neck pain. We report a case of absent congenital pedicle syndrome in a patient who presented with myelopathy and lower extremity weakness and review the literature on the surgical management of this entity. A 32-year-old woman with a history of systemic lupus erythematosus presented to the Neurosurgery Service with progressive weakness in her upper and lower extremities, clonus, and hyperreflexia. Magnetic resonance imaging revealed congenital absence of the pedicles of C2, C3, C4, C5, and C6 with a congenitally narrow canal at C4-5. The patient underwent a staged anterior and posterior cervical decompression and fusion. She was placed in a halo after surgery; at the 1-year follow-up, she was ambulatory with demonstrated improvement in weakness and fusion of her cervical spine. Absent congenital pedicle syndrome is rare, and most reported cases were treated conservatively. Surgical management is reserved for patients with myelopathy or instability. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Hydrogel scaffolds promote neural gene expression and structural reorganization in human astrocyte cultures

    Directory of Open Access Journals (Sweden)

    V. Bleu Knight

    2017-01-01

    Full Text Available Biomaterial scaffolds have the potential to enhance neuronal development and regeneration. Understanding the genetic responses of astrocytes and neurons to biomaterials could facilitate the development of synthetic environments that enable the specification of neural tissue organization with engineered scaffolds. In this study, we used high throughput transcriptomic and imaging methods to determine the impact of a hydrogel, PuraMatrix™, on human glial cells in vitro. Parallel studies were undertaken with cells grown in a monolayer environment on tissue culture polystyrene. When the Normal Human Astrocyte (NHA cell line is grown in a hydrogel matrix environment, the glial cells adopt a structural organization that resembles that of neuronal-glial cocultures, where neurons form clusters that are distinct from the surrounding glia. Statistical analysis of next generation RNA sequencing data uncovered a set of genes that are differentially expressed in the monolayer and matrix hydrogel environments. Functional analysis demonstrated that hydrogel-upregulated genes can be grouped into three broad categories: neuronal differentiation and/or neural plasticity, response to neural insult, and sensory perception. Our results demonstrate that hydrogel biomaterials have the potential to transform human glial cell identity, and may have applications in the repair of damaged brain tissue.

  1. Localization and identification of structural nonlinearities using cascaded optimization and neural networks

    Science.gov (United States)

    Koyuncu, A.; Cigeroglu, E.; Özgüven, H. N.

    2017-10-01

    In this study, a new approach is proposed for identification of structural nonlinearities by employing cascaded optimization and neural networks. Linear finite element model of the system and frequency response functions measured at arbitrary locations of the system are used in this approach. Using the finite element model, a training data set is created, which appropriately spans the possible nonlinear configurations space of the system. A classification neural network trained on these data sets then localizes and determines the types of all nonlinearities associated with the nonlinear degrees of freedom in the system. A new training data set spanning the parametric space associated with the determined nonlinearities is created to facilitate parametric identification. Utilizing this data set, initially, a feed forward regression neural network is trained, which parametrically identifies the classified nonlinearities. Then, the results obtained are further improved by carrying out an optimization which uses network identified values as starting points. Unlike identification methods available in literature, the proposed approach does not require data collection from the degrees of freedoms where nonlinear elements are attached, and furthermore, it is sufficiently accurate even in the presence of measurement noise. The application of the proposed approach is demonstrated on an example system with nonlinear elements and on a real life experimental setup with a local nonlinearity.

  2. [A novel computer-assisted drill template for atlantoaxial pedicle screw placement:a cadaveric experimental study].

    Science.gov (United States)

    Hu, Yong; Yuan, Zhen-shan; Xie, Hui; Yuan, Jian-bing; Dong, Wei-xin; Wang, Cheng-tao

    2013-09-03

    To validate the accuracy of atlanto-axial pedicle screw placement with a rapid prototyping drill guide template and analyze the factors of screw deviations. Computed tomography (CT) scan was performed in 16 cervical specimens. And three-dimension cervical vertebrae was reconstructed by Mimics software. The ideal trajectory for atlanto-axial pedicle screws was designed with a complementary basal template for posterior surface of atlanto-axial corresponding anatomical structure. Then drill guide template was materialized in a rapid prototyping machine. These templates were used during operation. The entry point and ideal and actual trajectories were measured after matching the positions of preoperative and postoperative specimens at designated coordinate axis. The average displacement of entry point of left and right C1 pedicle screw in x, y, z axis was (0.14 ± 0.59),(0.31 ± 1.32), (0.27 ± 0.68), (0.23 ± 0.55), (0.43 ± 1.21) and (0.30 ± 0.72) mm. And the average displacement of entry point of left and right C2 pedicle screw in m, n, p axis was (0.25 ± 0.85), (0.52 ± 1.52), (-0.27 ± 0.67), (0.44 ± 0.87), (0.38 ± 1.48), (-0.14 ± 0.62) mm.No statistically significant difference existed (P > 0.05) in deviation of entry point and between ideal and actual trajectories. Both human handling and inherent hardware and software factors are main reasons for a deviation of C1-C2 pedicle screw placement assisted by a rapid prototyping drill guide template.Ease of operation and individualized design are the advantages of drill guide template so as to greatly improve the precision of screw placement and reduce screw deviation.

  3. In vitro validation of a novel mechanical model for testing the anchorage capacity of pedicle screws using physiological load application.

    Science.gov (United States)

    Liebsch, Christian; Zimmermann, Julia; Graf, Nicolas; Schilling, Christoph; Wilke, Hans-Joachim; Kienle, Annette

    2018-01-01

    Biomechanical in vitro tests analysing screw loosening often include high standard deviations caused by high variabilities in bone mineral density and pedicle geometry, whereas standardized mechanical models made of PU foam often do not integrate anatomical or physiological boundary conditions. The purpose of this study was to develop a most realistic mechanical model for the standardized and reproducible testing of pedicle screws regarding the resistance against screw loosening and the holding force as well as to validate this model by in vitro experiments. The novel mechanical testing model represents all anatomical structures of a human vertebra and is consisting of PU foam to simulate cancellous bone, as well as a novel pedicle model made of short carbon fibre filled epoxy. Six monoaxial cannulated pedicle screws (Ø6.5 × 45mm) were tested using the mechanical testing model as well as human vertebra specimens by applying complex physiological cyclic loading (shear, tension, and bending; 5Hz testing frequency; sinusoidal pulsating forces) in a dynamic materials testing machine with stepwise increasing load after each 50.000 cycles (100.0N shear force + 20.0N per step, 51.0N tension force + 10.2N per step, 4.2Nm bending moment + 0.8Nm per step) until screw loosening was detected. The pedicle screw head was fixed on a firmly clamped rod while the load was applied in the vertebral body. For the in vitro experiments, six human lumbar vertebrae (L1-3, BMD 75.4 ± 4.0mg/cc HA, pedicle width 9.8 ± 0.6mm) were tested after implanting pedicle screws under X-ray control. Relative motions of pedicle screw, specimen fixture, and rod fixture were detected using an optical motion tracking system. Translational motions of the mechanical testing model experiments in the point of load introduction (0.9-2.2mm at 240N shear force) were reproducible within the variation range of the in vitro experiments (0.6-3.5mm at 240N shear force). Screw loosening occurred continuously in

  4. Predicting physical-chemical properties of compounds from molecular structures by recursive neural networks.

    Science.gov (United States)

    Bernazzani, Luca; Duce, Celia; Micheli, Alessio; Mollica, Vincenzo; Sperduti, Alessandro; Starita, Antonina; Tiné, Maria Rosaria

    2006-01-01

    In this paper, we report on the potential of a recently developed neural network for structures applied to the prediction of physical chemical properties of compounds. The proposed recursive neural network (RecNN) model is able to directly take as input a structured representation of the molecule and to model a direct and adaptive relationship between the molecular structure and target property. Therefore, it combines in a learning system the flexibility and general advantages of a neural network model with the representational power of a structured domain. As a result, a completely new approach to quantitative structure-activity relationship/quantitative structure-property relationship (QSPR/QSAR) analysis is obtained. An original representation of the molecular structures has been developed accounting for both the occurrence of specific atoms/groups and the topological relationships among them. Gibbs free energy of solvation in water, Delta(solv)G degrees , has been chosen as a benchmark for the model. The different approaches proposed in the literature for the prediction of this property have been reconsidered from a general perspective. The advantages of RecNN as a suitable tool for the automatization of fundamental parts of the QSPR/QSAR analysis have been highlighted. The RecNN model has been applied to the analysis of the Delta(solv)G degrees in water of 138 monofunctional acyclic organic compounds and tested on an external data set of 33 compounds. As a result of the statistical analysis, we obtained, for the predictive accuracy estimated on the test set, correlation coefficient R = 0.9985, standard deviation S = 0.68 kJ mol(-1), and mean absolute error MAE = 0.46 kJ mol(-1). The inherent ability of RecNN to abstract chemical knowledge through the adaptive learning process has been investigated by principal components analysis of the internal representations computed by the network. It has been found that the model recognizes the chemical compounds on the

  5. [A comparative study on treatment of thoracolumbar fracture with injured vertebra pedicle instrumentation and cross segment pedicle instrumentation].

    Science.gov (United States)

    Yin, Fei; Sun, Zhenzhong; Yin, Qudong; Liu, Jun; Gu, Sanjun; Zhang, Shaodong

    2014-02-01

    To compare the effective of short-segment pedicle instrumentation with bone grafting and pedicle screw implanting in injured vertebra and cross segment pedicle instrumentation with bone grafting in injured vertebra for treating thoracolumbar fractures. A prospective randomized controlled study was performed in 40 patients with thoracolumbar fracture who were in accordance with the inclusive criteria between June 2010 and June 2012. Of 40 patients, 20 received treatment with short-segment pedicle screw instrumentation with bone grafting and pedicle screw implanting in injured vertebra in group A, and 20 received treatment with cross segment pedicle instrumentation with bone grafting in injured vertebra in group B. There was no significant difference in gender, age, affected segment, disease duration, Frankel grade, Cobb angle, compression rate of anterior verterbral height, visual analogue scale (VAS) score, and Japanese Orthopaedic Association (JOA) score between 2 groups before operation (P > 0.05). The operation time, blood loss, Cobb angle, compression rate of anterior vertebral height, loss of disc space height, Frankel grade, VAS and JOA scores were compared between 2 groups. There was no significant difference in the operation time and blood loss between 2 groups (P > 0.05). Primary healing of incision was obtained in all patients, and no early complication of infection or lower limb vein thrombus occurred. Forty patients were followed up 12-16 months (mean, 14.8 months). No breaking or displacement of internal fixation was observed. The improvement of Frankel grading score was 0.52 +/- 0.72 in group A and 0.47 +/- 0.63 in group B, showing no significant difference (t = 0.188, P = 0.853) at 12 months after operation. The Cobb angle, compression rate of anterior verterbral height, and VAS score at 1 week and 12 months, and JOA score at 12 months were significantly improved when compared with preoperative ones in 2 groups (P 0.05), but the compression rate of

  6. Tracting the neural basis of music: Deficient structural connectivity underlying acquired amusia.

    Science.gov (United States)

    Sihvonen, Aleksi J; Ripollés, Pablo; Särkämö, Teppo; Leo, Vera; Rodríguez-Fornells, Antoni; Saunavaara, Jani; Parkkola, Riitta; Soinila, Seppo

    2017-12-01

    Acquired amusia provides a unique opportunity to investigate the fundamental neural architectures of musical processing due to the transition from a functioning to defective music processing system. Yet, the white matter (WM) deficits in amusia remain systematically unexplored. To evaluate which WM structures form the neural basis for acquired amusia and its recovery, we studied 42 stroke patients longitudinally at acute, 3-month, and 6-month post-stroke stages using DTI [tract-based spatial statistics (TBSS) and deterministic tractography (DT)] and the Scale and Rhythm subtests of the Montreal Battery of Evaluation of Amusia (MBEA). Non-recovered amusia was associated with structural damage and subsequent degeneration in multiple WM tracts including the right inferior fronto-occipital fasciculus (IFOF), arcuate fasciculus (AF), inferior longitudinal fasciculus (ILF), uncinate fasciculus (UF), and frontal aslant tract (FAT), as well as in the corpus callosum (CC) and its posterior part (tapetum). In a linear regression analysis, the volume of the right IFOF was the main predictor of MBEA performance across time. Overall, our results provide a comprehensive picture of the large-scale deficits in intra- and interhemispheric structural connectivity underlying amusia, and conversely highlight which pathways are crucial for normal music perception. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Prediction of Maximum Story Drift of MDOF Structures under Simulated Wind Loads Using Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Omar Payán-Serrano

    2017-05-01

    Full Text Available The aim of this paper is to investigate the prediction of maximum story drift of Multi-Degree of Freedom (MDOF structures subjected to dynamics wind load using Artificial Neural Networks (ANNs through the combination of several structural and turbulent wind parameters. The maximum story drift of 1600 MDOF structures under 16 simulated wind conditions are computed with the purpose of generating the data set for the networks training with the Levenberg–Marquardt method. The Shinozuka and Newmark methods are used to simulate the turbulent wind and dynamic response, respectively. In order to optimize the computational time required for the dynamic analyses, an array format based on the Shinozuka method is presented to perform the parallel computing. Finally, it is observed that the already trained ANNs allow for predicting adequately the maximum story drift with a correlation close to 99%.

  8. [Renaissance of pedicled flaps in oral and maxillofacial surgery].

    Science.gov (United States)

    Twieg, M; Reich, W; Dempf, R; Eckert, A W

    2014-06-01

    A retrospective analysis in the period 2007 to 2011 included 71 surgically treated patients for carcinoma of the head and neck region and subsequent reconstruction with 36 pedicled distant flaps and 47 free flaps. Patient specific parameters of data collection with SPSS 17.0 were age and sex distribution, TNM stage and treatment. The specific type of flap reconstruction, duration of surgery, complications, intensive care and inpatient treatment were recorded. The results showed that the healing process was uneventful in 26 (72.2 %) pedicled flaps, 14 (38.9 %) pedicled flaps were transplanted in a preoperatively irradiated area of the head and neck region and in 86.0 % with a positive healing process. Tumor stage, general physical condition of the patient and type of therapy are the key parameters for the choice of reconstruction.

  9. Structural Analysis of Three-dimensional Human Neural Tissue derived from Induced Pluripotent Stem Cells

    DEFF Research Database (Denmark)

    Terrence Brooks, Patrick; Rasmussen, Mikkel Aabech; Hyttel, Poul

    2016-01-01

    Objective: The present study aimed at establishing a method for production of a three-dimensional (3D) human neural tissue derived from induced pluripotent stem cells (iPSCs) and analyzing the outcome by a combination of tissue ultrastructure and expression of neural markers. Methods: A two......-step cell culture procedure was implemented by subjecting human iPSCs to a 3D scaffoldbased neural differentiation protocol. First, neural fate-inducing small molecules were used to create a neuroepithelial monolayer. Second, the monolayer was trypsinized into single cells and seeded into a porous...... polystyrene scaffold and further cultured to produce a 3D neural tissue. The neural tissue was characterized by a combination of immunohistochemistry and transmission electron microscopy (TEM). Results: iPSCs developed into a 3D neural tissue expressing markers for neural progenitor cells, early neural...

  10. Crystal structure of the Ig1 domain of the neural cell adhesion molecule NCAM2 displays domain swapping

    DEFF Research Database (Denmark)

    Rasmussen, Kim Krighaar; Kulahin, Nikolaj; Kristensen, Ole

    2008-01-01

    The crystal structure of the first immunoglobulin (Ig1) domain of neural cell adhesion molecule 2 (NCAM2/OCAM/RNCAM) is presented at a resolution of 2.7 A. NCAM2 is a member of the immunoglobulin superfamily of cell adhesion molecules (IgCAMs). In the structure, two Ig domains interact by domain...

  11. Real-time vibration-based structural damage detection using one-dimensional convolutional neural networks

    Science.gov (United States)

    Abdeljaber, Osama; Avci, Onur; Kiranyaz, Serkan; Gabbouj, Moncef; Inman, Daniel J.

    2017-02-01

    Structural health monitoring (SHM) and vibration-based structural damage detection have been a continuous interest for civil, mechanical and aerospace engineers over the decades. Early and meticulous damage detection has always been one of the principal objectives of SHM applications. The performance of a classical damage detection system predominantly depends on the choice of the features and the classifier. While the fixed and hand-crafted features may either be a sub-optimal choice for a particular structure or fail to achieve the same level of performance on another structure, they usually require a large computation power which may hinder their usage for real-time structural damage detection. This paper presents a novel, fast and accurate structural damage detection system using 1D Convolutional Neural Networks (CNNs) that has an inherent adaptive design to fuse both feature extraction and classification blocks into a single and compact learning body. The proposed method performs vibration-based damage detection and localization of the damage in real-time. The advantage of this approach is its ability to extract optimal damage-sensitive features automatically from the raw acceleration signals. Large-scale experiments conducted on a grandstand simulator revealed an outstanding performance and verified the computational efficiency of the proposed real-time damage detection method.

  12. Effect of synapse dilution on the memory retrieval in structured attractor neural networks

    Science.gov (United States)

    Brunel, N.

    1993-08-01

    We investigate a simple model of structured attractor neural network (ANN). In this network a module codes for the category of the stored information, while another group of neurons codes for the remaining information. The probability distribution of stabilities of the patterns and the prototypes of the categories are calculated, for two different synaptic structures. The stability of the prototypes is shown to increase when the fraction of neurons coding for the category goes down. Then the effect of synapse destruction on the retrieval is studied in two opposite situations : first analytically in sparsely connected networks, then numerically in completely connected ones. In both cases the behaviour of the structured network and that of the usual homogeneous networks are compared. When lesions increase, two transitions are shown to appear in the behaviour of the structured network when one of the patterns is presented to the network. After the first transition the network recognizes the category of the pattern but not the individual pattern. After the second transition the network recognizes nothing. These effects are similar to syndromes caused by lesions in the central visual system, namely prosopagnosia and agnosia. In both types of networks (structured or homogeneous) the stability of the prototype is greater than the stability of individual patterns, however the first transition, for completely connected networks, occurs only when the network is structured.

  13. Functional and structural neural network characterization of serotonin transporter knockout rats.

    Directory of Open Access Journals (Sweden)

    Kajo van der Marel

    Full Text Available Brain serotonin homeostasis is crucially maintained by the serotonin transporter (5-HTT, and its down-regulation has been linked to increased vulnerability for anxiety- and depression-related behavior. Studies in 5-HTT knockout (5-HTT(-/- rodents have associated inherited reduced functional expression of 5-HTT with increased sensitivity to adverse as well as rewarding environmental stimuli, and in particular cocaine hyperresponsivity. 5-HTT down-regulation may affect normal neuronal wiring of implicated corticolimbic cerebral structures. To further our understanding of its contribution to potential alterations in basal functional and structural properties of neural network configurations, we applied resting-state functional MRI (fMRI, pharmacological MRI of cocaine-induced activation, and diffusion tensor imaging (DTI in 5-HTT(-/- rats and wild-type controls (5-HTT(+/+. We found that baseline functional connectivity values and cocaine-induced neural activity within the corticolimbic network was not significantly altered in 5-HTT(-/- versus 5-HTT(+/+ rats. Similarly, DTI revealed mostly intact white matter structural integrity, except for a reduced fractional anisotropy in the genu of the corpus callosum of 5-HTT(-/- rats. At the macroscopic level, analyses of complex graphs constructed from either functional connectivity values or structural DTI-based tractography results revealed that key properties of brain network organization were essentially similar between 5-HTT(+/+ and 5-HTT(-/- rats. The individual tests for differences between 5-HTT(+/+ and 5-HTT(-/- rats were capable of detecting significant effects ranging from 5.8% (fractional anisotropy to 26.1% (pharmacological MRI and 29.3% (functional connectivity. Tentatively, lower fractional anisotropy in the genu of the corpus callosum could indicate a reduced capacity for information integration across hemispheres in 5-HTT(-/- rats. Overall, the comparison of 5-HTT(-/- and wild-type rats

  14. Structural neural correlates of multitasking: A voxel-based morphometry study.

    Science.gov (United States)

    Zhang, Rui-Ting; Yang, Tian-Xiao; Wang, Yi; Sui, Yuxiu; Yao, Jingjing; Zhang, Chen-Yuan; Cheung, Eric F C; Chan, Raymond C K

    2016-12-01

    Multitasking refers to the ability to organize assorted tasks efficiently in a short period of time, which plays an important role in daily life. However, the structural neural correlates of multitasking performance remain unclear. The present study aimed at exploring the brain regions associated with multitasking performance using global correlation analysis. Twenty-six healthy participants first underwent structural brain scans and then performed the modified Six Element Test, which required participants to attempt six subtasks in 10 min while obeying a specific rule. Voxel-based morphometry of the whole brain was used to detect the structural correlates of multitasking ability. Grey matter volume of the anterior cingulate cortex (ACC) was positively correlated with the overall performance and time monitoring in multitasking. In addition, white matter volume of the anterior thalamic radiation (ATR) was also positively correlated with time monitoring during multitasking. Other related brain regions associated with multitasking included the superior frontal gyrus, the inferior occipital gyrus, the lingual gyrus, and the inferior longitudinal fasciculus. No significant correlation was found between grey matter volume of the prefrontal cortex (Brodmann Area 10) and multitasking performance. Using a global correlation analysis to examine various aspects of multitasking performance, this study provided new insights into the structural neural correlates of multitasking ability. In particular, the ACC was identified as an important brain region that played both a general and a specific time-monitoring role in multitasking, extending the role of the ACC from lesioned populations to healthy populations. The present findings also support the view that the ATR may influence multitasking performance by affecting time-monitoring abilities. © 2016 The Institute of Psychology, Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

  15. Surgical outcome of posterior decompression, posterolateral fusion and stabilization by pedicle screw and rod in thoracolumbar tuberculosis

    Directory of Open Access Journals (Sweden)

    Md. Anowarul Islam

    2017-05-01

    Full Text Available Spinal tuberculosis causes severe complications like neurological and spinal deformity which may lead to respiratory distress, costo-pelvic impingement, paraplegia and consequent reduction in the quality and longevity of life. The aim of the present treatment is to avoid the consequence of neural complications and gain near-normal spine. Mechanical factor causes pathological fracture or dislocation of an affected vertebral body. Surgical decompression ensues further instability. Reconstruction of spinal column by pedicle screw and rod provide stability and prevents secondary neural damage and deformity thereby helps in early mobilization. Prospective study was done to evaluate the results in 20 cases of spinal tuberculosis in thoracolumbar region associated with neurological deficit. We operated our cases (12 males and 8 females by posterolateral decompression, fusion and stabilization by pedicle screw and rod along with antitubercular drug treatment. All patients were with neurological deficit, single level involvement and 10 to 30 degree of mild kyphosis. After surgery, kyphosis improved from 20.7 ± 5.5 degrees to 12.5 ± 3.9 degree. Bony fusion was in 65.0% cases. Neurological improvement and pain subsided in all the patients.

  16. Congenital hypoplasia of the lumbar pedicle with spondylolisthesis: report of 2 cases.

    Science.gov (United States)

    Hsieh, Chang-Sheng; Lee, Sang-Ho; Lee, Hyung Chang; Oh, Hyeong-Seok; Hwang, Byeong-Wook; Park, Sang-Joon; Chen, Jian-Han

    2017-04-01

    Congenital hypoplasia of the spinal pedicle is a rare condition. Previously reported cases were treated conservatively or with posterior instrumented fusion. However, the absence or hypoplasia of the lumbar pedicle may increase the difficulty of pedicle screw fixation and fusion. Herein, the authors describe 2 cases of rare adult congenital hypoplasia of the right lumbar pedicles associated with spondylolisthesis. The patients underwent anterior lumbar interbody fusion with a stand-alone cage as well as percutaneous pedicle screw fixation. This method was used to avoid the difficulties associated with pedicle screw fixation and to attain solid fusion. Both patients achieved satisfactory outcomes after a minimum of 2 years of follow-up. This method may be an alternative for patients with congenital hypoplasia of the lumbar spinal pedicle.

  17. scrotal reconstruction with a pedicled gracilis muscle flap after ...

    African Journals Online (AJOL)

    better functional and cosmetic outcomes. Muscle and myocutaneous flaps like gracilis, rectus abdominis, split gluteus maximus flaps are needed for large skin defects with deep pockets or cavities to eliminate the dead space (2,3). The pedicled or free greater omental flap as well as scrotal tissue expansion have also been ...

  18. Positioning of pedicle screws in adolescent idiopathic scoliosis using electromyography

    Directory of Open Access Journals (Sweden)

    Bruno Moreira Gavassi

    2015-06-01

    Full Text Available OBJECTIVE: To analyze the occurrence of poor positioning of pedicle screws inserted with the aid of intraoperative electromyographic stimulation in the treatment of Adolescent Idiopathic Scoliosis (AIS.METHODS: This is a prospective observational study including all patients undergoing surgical treatment for AIS, between March and December 2013 at a single institution. All procedures were monitored by electromyography of the inserted pedicle screws. The position of the screws was evaluated by assessment of postoperative CT and classified according to the specific AIS classification system.RESULTS: Sixteen patients were included in the study, totalizing 281 instrumented pedicles (17.5 per patient. No patient had any neurological deficit or complaint after surgery. In the axial plane, 195 screws were found in ideal position (69.4% while in the sagittal plane, 226 screws were found in ideal position (80.4%. Considering both the axial and the sagittal planes, it was observed that 59.1% (166/281 of the screws did not violate any cortical wall.CONCLUSION: The use of pedicle screws proved to be a safe technique without causing neurological damage in AIS surgeries, even with the occurrence of poor positioning of some implants.

  19. Adaptive remodeling at the pedicle due to pars fracture: a finite element analysis study.

    Science.gov (United States)

    İnceoğlu, Serkan; Mageswaran, Prasath; Modic, Michael T; Benzel, Edward C

    2014-09-01

    Spondylolysis is a common condition among the general population and a major cause of back pain in young athletes. This condition can be difficult to detect with plain radiography and has been reported to lead to contralateral pars fracture or pedicle fracture in the terminal stages. Interestingly, some patients with late-stage spondylolysis are observed to have radiographic or CT evidence of a sclerotic pedicle on the side contralateral to the spondylolysis. Although computational studies have shown stress elevation in the contralateral pedicle after a pars fracture, it is not known if these changes would cause sclerotic changes in the contralateral pedicle. The objective of this study was to investigate the adaptive remodeling process at the pedicle due to a contralateral spondylolysis using finite element analysis. A multiscale finite element model of a vertebra was obtained by combining a continuum model of the posterior elements with a voxel-based pedicle section. Extension loading conditions were applied with or without a fracture at the contralateral pars to analyze the stresses in the contralateral pedicle. A remodeling algorithm was used to simulate and assess density changes in the contralateral pedicle. The remodeling algorithm demonstrated an increase in bone formation around the perimeter of the contralateral pedicle with some localized loss of mass in the region of cancellous bone. The authors' results indicated that a pars fracture results in sclerotic changes in the contralateral pedicle. Such a remodeling process could increase overall bone mass. However, focal bone loss in the region of the cancellous bone of the pedicle might predispose the pedicle to microfractures. This phenomenon explains, at least in part, the origin of pedicle stress fractures in the sclerotic contralateral pedicles of patients with unilateral spondylolysis.

  20. Artificial-neural-network-based classification of mammographic microcalcifications using image structure features

    Science.gov (United States)

    Dhawan, Atam P.; Chitre, Yateen S.; Moskowitz, Myron

    1993-07-01

    Mammography associated with clinical breast examination and self-breast examination is the only effective and viable method for mass breast screening. It is however, difficult to distinguish between benign and malignant microcalcifications associated with breast cancer. Most of the techniques used in the computerized analysis of mammographic microcalcifications segment the digitized gray-level image into regions representing microcalcifications. We present a second-order gray-level histogram based feature extraction approach to extract microcalcification features. These features, called image structure features, are computed from the second-order gray-level histogram statistics, and do not require segmentation of the original image into binary regions. Several image structure features were computed for 100 cases of `difficult to diagnose' microcalcification cases with known biopsy results. These features were analyzed in a correlation study which provided a set of five best image structure features. A feedforward backpropagation neural network was used to classify mammographic microcalcifications using the image structure features. The network was trained on 10 cases of mammographic microcalcifications and tested on additional 85 `difficult-to-diagnose' microcalcifications cases using the selected image structure features. The trained network yielded good results for classification of `difficult-to- diagnose' microcalcifications into benign and malignant categories.

  1. Pedicle screw versus hybrid posterior instrumentation for dystrophic neurofibromatosis scoliosis.

    Science.gov (United States)

    Wang, Jr-Yi; Lai, Po-Liang; Chen, Wen-Jer; Niu, Chi-Chien; Tsai, Tsung-Ting; Chen, Lih-Huei

    2017-06-01

    Surgical management of severe rigid dystrophic neurofibromatosis (NF) scoliosis is technically demanding and produces varying results. In the current study, we reviewed 9 patients who were treated with combined anterior and posterior fusion using different types of instrumentation (i.e., pedicle screw, hybrid, and all-hook constructs) at our institute.Between September 2001 and July 2010 at our institute, 9 patients received anterior release/fusion and posterior fusion with different types of instrumentation, including a pedicle screw construct (n = 5), a hybrid construct (n = 3), and an all-hook construct (n = 1). We compared the pedicle screw group with the hybrid group to analyze differences in preoperative curve angle, immediate postoperative curve reduction, and latest follow-up curve angle.The mean follow-up period was 9.5 ± 2.9 years. The average age at surgery was 10.3 ± 3.9 years. The average preoperative scoliosis curve was 61.3 ± 13.8°, and the average preoperative kyphosis curve was 39.8 ± 19.7°. The average postoperative scoliosis and kyphosis curves were 29.7 ± 10.7° and 21.0 ± 13.5°, respectively. The most recent follow-up scoliosis and kyphosis curves were 43.4 ± 17.3° and 29.4 ± 18.9°, respectively. There was no significant difference in the correction angle (either coronal or sagittal), and there was no significant difference in the loss of sagittal correction between the pedicle screw construct group and the hybrid construct group. However, the patients who received pedicle screw constructs had significantly less loss of coronal correction (P instrumentation, one with an all-hook construct and the other with a hybrid construct, required surgical revision because of progression of deformity.It is difficult to intraoperatively correct dystrophic deformity and to maintain this correction after surgery. Combined anterior release/fusion and posterior fusion using either a pedicle screw

  2. A closer look at the apparent correlation of structural and functional connectivity in excitable neural networks

    Science.gov (United States)

    Messé, Arnaud; Hütt, Marc-Thorsten; König, Peter; Hilgetag, Claus C.

    2015-01-01

    The relationship between the structural connectivity (SC) and functional connectivity (FC) of neural systems is a central focus in brain network science. It is an open question, however, how strongly the SC-FC relationship depends on specific topological features of brain networks or the models used for describing excitable dynamics. Using a basic model of discrete excitable units that follow a susceptible - excited - refractory dynamic cycle (SER model), we here analyze how functional connectivity is shaped by the topological features of a neural network, in particular its modularity. We compared the results obtained by the SER model with corresponding simulations by another well established dynamic mechanism, the Fitzhugh-Nagumo model, in order to explore general features of the SC-FC relationship. We showed that apparent discrepancies between the results produced by the two models can be resolved by adjusting the time window of integration of co-activations from which the FC is derived, providing a clearer distinction between co-activations and sequential activations. Thus, network modularity appears as an important factor shaping the FC-SC relationship across different dynamic models.

  3. CNNdel: Calling Structural Variations on Low Coverage Data Based on Convolutional Neural Networks

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2017-01-01

    Full Text Available Many structural variations (SVs detection methods have been proposed due to the popularization of next-generation sequencing (NGS. These SV calling methods use different SV-property-dependent features; however, they all suffer from poor accuracy when running on low coverage sequences. The union of results from these tools achieves fairly high sensitivity but still produces low accuracy on low coverage sequence data. That is, these methods contain many false positives. In this paper, we present CNNdel, an approach for calling deletions from paired-end reads. CNNdel gathers SV candidates reported by multiple tools and then extracts features from aligned BAM files at the positions of candidates. With labeled feature-expressed candidates as a training set, CNNdel trains convolutional neural networks (CNNs to distinguish true unlabeled candidates from false ones. Results show that CNNdel works well with NGS reads from 26 low coverage genomes of the 1000 Genomes Project. The paper demonstrates that convolutional neural networks can automatically assign the priority of SV features and reduce the false positives efficaciously.

  4. A hybrid neural network structure for application to nondestructive TRU waste assay

    Energy Technology Data Exchange (ETDEWEB)

    Becker, G. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1995-12-31

    The determination of transuranic (TRU) and associated radioactive material quantities entrained in waste forms is a necessary component. of waste characterization. Measurement performance requirements are specified in the National TRU Waste Characterization Program quality assurance plan for which compliance must be demonstrated prior to the transportation and disposition of wastes. With respect to this criterion, the existing TRU nondestructive waste assay (NDA) capability is inadequate for a significant fraction of the US Department of Energy (DOE) complex waste inventory. This is a result of the general application of safeguard-type measurement and calibration schemes to waste form configurations. Incompatibilities between such measurement methods and actual waste form configurations complicate regulation compliance demonstration processes and illustrate the need for an alternate measurement interpretation paradigm. Hence, it appears necessary to supplement or perhaps restructure the perceived solution and approach to the waste NDA problem. The first step is to understand the magnitude of the waste matrix/source attribute space associated with those waste form configurations in inventory and how this creates complexities and unknowns with respect to existing NDA methods. Once defined and/or bounded, a conceptual method must be developed that specifies the necessary tools and the framework in which the tools are used. A promising framework is a hybridized neural network structure. Discussed are some typical complications associated with conventional waste NDA techniques and how improvements can be obtained through the application of neural networks.

  5. Subcutaneous pedicle propeller flap: An old technique revisited and modified!

    Directory of Open Access Journals (Sweden)

    Durga Karki

    2016-01-01

    Full Text Available Background: Post-burn axillary and elbow scar contracture is a challenging problem to the reconstructive surgeon owing to the wide range of abduction and extension that should be achieved, respectively, while treating either of the joint. The aim of this paper is to highlight the use of subcutaneous pedicle propeller flap for the management of post-burn axillary and elbow contractures. Methodology: This is a prospective case study of axillary and elbow contractures managed at a tertiary care hospital using propeller flap based on subcutaneous pedicle from 2009 to 2014. Surgical treatment comprised of subcutaneous-based pedicle propeller flap from the normal tissue within the contracture based on central axis pedicle. The flap was rotated axially to break the contracture. The technique further encompassed a modification, a Zig-Zag incision of the flap, which was seen to prevent hypertrophy along the incision line. There was a mean period of 12 months of follow-up. Results: Thirty-eight patients consisting of 22 males and 16 females were included in this study among which 23 patients had Type II axillary contractures and 15 had moderate flexion contractures at elbow joint. The post-operative abduction achieved at shoulder joint had a mean of 168° whereas extension achieved at elbow had a mean of 175°. The functional and aesthetic results were satisfactory. Conclusion: The choice of surgical procedure for reconstruction of post-burn upper extremity contractures should be made according to the pattern of scar contracture and the state of surrounding skin. The choice of subcutaneous pedicle propeller flap should be emphasised because of the superior functional results of flap as well as ease to learn it. Moreover, the modification of propeller flap described achieves better results in terms of scar healing. There is an inter-positioning of healthy skin in between the graft, so it prevents scar band formation all around the flap.

  6. Incorporation of iodine into apatite structure: a crystal chemistry approach using Artificial Neural Network

    Science.gov (United States)

    Wang, Jianwei

    2015-06-01

    Materials with apatite crystal structure provide a great potential for incorporating the long-lived radioactive iodine isotope (129I) in the form of iodide (I-) from nuclear waste streams. Because of its durability and potentially high iodine content, the apatite waste form can reduce iodine release rate and minimize the waste volume. Crystal structure and composition of apatite was investigated for iodide incorporation into the channel of the structure using Artificial Neural Network. A total of 86 experimentally determined apatite crystal structures of different compositions were compiled from literature, and 46 of them were used to train the networks and 42 were used to test the performance of the trained networks. The results show that the performances of the networks are satisfactory for predictions of unit cell parameters a and c and channel size of the structure. The trained and tested networks were then used to predict unknown compositions of apatite that incorporates iodide. With a crystal chemistry consideration, chemical compositions that lead to matching the size of the structural channel to the size of iodide were then predicted to be able to incorporate iodide in the structural channel. The calculations suggest that combinations of A site cations of Ag+, K+, Sr2+, Pb2+, Ba2+, and Cs+, and X site cations, mostly formed tetrahedron, of Mn5+, As5+, Cr5+, V5+, Mo5+, Si4+, Ge4+, and Re7+ are possible apatite compositions that are able to incorporate iodide. The charge balance of different apatite compositions can be achieved by multiple substitutions at a single site or coupled substitutions at both A and X sites. The results give important clues for designing experiments to synthesize new apatite compositions and also provide a fundamental understanding how iodide is incorporated in the apatite structure. This understanding can provide important insights for apatite waste forms design by optimizing the chemical composition and synthesis procedure.

  7. Clinical pedicle screw accuracy and deviation from planning in robot-guided spine surgery: robot-guided pedicle screw accuracy

    NARCIS (Netherlands)

    van Dijk, Joris David; Ende, Roy P.J.; Stramigioli, Stefano; Köchling, Matthias; Höss, Norbert

    STUDY DESIGN: A retrospective chart review was performed for 112 consecutive minimally invasive spinal surgery patients who underwent pedicular screw fixation in a community hospital setting. OBJECTIVE: To assess the clinical accuracy and deviation in screw positions in robot-assisted pedicle screw

  8. Quantitative dual-energy CT for phantomless evaluation of cancellous bone mineral density of the vertebral pedicle: correlation with pedicle screw pull-out strength

    Energy Technology Data Exchange (ETDEWEB)

    Wichmann, Julian L.; Booz, Christian; Bauer, Ralf W.; Kerl, J.M.; Fischer, Sebastian; Lehnert, Thomas; Vogl, Thomas J.; Khan, M.F. [University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt am Main (Germany); Wesarg, Stefan [Fraunhofer IGD, Cognitive Computing and Medical Imaging, Darmstadt (Germany); Kafchitsas, Konstantinos [Spine Center, Asklepios Klinik Lindenlohe, Schwandorf (Germany)

    2015-06-01

    To evaluate quantitative dual-energy computed tomography (DECT) for phantomless analysis of cancellous bone mineral density (BMD) of vertebral pedicles and to assess the correlation with pedicle screw pull-out strength. Twenty-nine thoracic and lumbar vertebrae from cadaver specimens were examined with DECT. Using dedicated post-processing software, a pedicle screw vector was mapped (R1, intrapedicular segment of the pedicle vector; R2, intermediate segment; R3, intracorporal segment; global, all segments) and BMD was calculated. To invasively evaluate pedicle stability, pedicle screws were drilled through both pedicles and left pedicle screw pull-out strength was measured. Resulting values were correlated using the paired t test and Pearson's linear correlation. Average pedicle screw vector BMD (R1, 0.232 g/cm{sup 3}; R2, 0.166 g/cm{sup 3}; R3, 0.173 g/cm{sup 3}; global, 0.236 g/cm{sup 3}) showed significant differences between R1-R2 (P < 0.002) and R1-R3 (P < 0.034) segments while comparison of R2-R3 did not reach significance (P > 0.668). Average screw pull-out strength (639.2 N) showed a far stronger correlation with R1 (r = 0.80; P < 0.0001) than global BMD (r = 0.42; P = 0.025), R2 (r = 0.37; P = 0.048) and R3 (r = -0.33; P = 0.078) segments. Quantitative DECT allows for phantomless BMD assessment of the vertebral pedicle. BMD of the intrapedicular segment shows a significantly stronger correlation with pedicle screw pull-out strength than other segments. (orig.)

  9. A simple structure wavelet transform circuit employing function link neural networks and SI filters

    Science.gov (United States)

    Mu, Li; Yigang, He

    2016-12-01

    Signal processing by means of analog circuits offers advantages from a power consumption viewpoint. Implementing wavelet transform (WT) using analog circuits is of great interest when low-power consumption becomes an important issue. In this article, a novel simple structure WT circuit in analog domain is presented by employing functional link neural network (FLNN) and switched-current (SI) filters. First, the wavelet base is approximated using FLNN algorithms for giving a filter transfer function that is suitable for simple structure WT circuit implementation. Next, the WT circuit is constructed with the wavelet filter bank, whose impulse response is the approximated wavelet and its dilations. The filter design that follows is based on a follow-the-leader feedback (FLF) structure with multiple output bilinear SI integrators and current mirrors as the main building blocks. SI filter is well suited for this application since the dilation constant across different scales of the transform can be precisely implemented and controlled by the clock frequency of the circuit with the same system architecture. Finally, to illustrate the design procedure, a seventh-order FLNN-approximated Gaussian wavelet is implemented as an example. Simulations have successfully verified that the designed simple structure WT circuit has low sensitivity, low-power consumption and litter effect to the imperfections.

  10. The necessity of connection structures in neural models of variable binding.

    Science.gov (United States)

    van der Velde, Frank; de Kamps, Marc

    2015-08-01

    In his review of neural binding problems, Feldman (Cogn Neurodyn 7:1-11, 2013) addressed two types of models as solutions of (novel) variable binding. The one type uses labels such as phase synchrony of activation. The other ('connectivity based') type uses dedicated connections structures to achieve novel variable binding. Feldman argued that label (synchrony) based models are the only possible candidates to handle novel variable binding, whereas connectivity based models lack the flexibility required for that. We argue and illustrate that Feldman's analysis is incorrect. Contrary to his conclusion, connectivity based models are the only viable candidates for models of novel variable binding because they are the only type of models that can produce behavior. We will show that the label (synchrony) based models analyzed by Feldman are in fact examples of connectivity based models. Feldman's analysis that novel variable binding can be achieved without existing connection structures seems to result from analyzing the binding problem in a wrong frame of reference, in particular in an outside instead of the required inside frame of reference. Connectivity based models can be models of novel variable binding when they possess a connection structure that resembles a small-world network, as found in the brain. We will illustrate binding with this type of model with episode binding and the binding of words, including novel words, in sentence structures.

  11. Neural-Net Based Optical NDE Method for Structural Health Monitoring

    Science.gov (United States)

    Decker, Arthur J.; Weiland, Kenneth E.

    2003-01-01

    This paper answers some performance and calibration questions about a non-destructive-evaluation (NDE) procedure that uses artificial neural networks to detect structural damage or other changes from sub-sampled characteristic patterns. The method shows increasing sensitivity as the number of sub-samples increases from 108 to 6912. The sensitivity of this robust NDE method is not affected by noisy excitations of the first vibration mode. A calibration procedure is proposed and demonstrated where the output of a trained net can be correlated with the outputs of the point sensors used for vibration testing. The calibration procedure is based on controlled changes of fastener torques. A heterodyne interferometer is used as a displacement sensor for a demonstration of the challenges to be handled in using standard point sensors for calibration.

  12. Safe corridor for the implantation of thoracolumbar pedicle screws in growing pigs: A morphometric study.

    Directory of Open Access Journals (Sweden)

    Thibaut Cachon

    Full Text Available The pig spine is widely used as a large animal model for preclinical research in human medicine to test new spinal implants and surgical procedures. Among them, pedicle screw is one of the most common method of fixation of those implants. However, the pedicle of the porcine vertebra is not as well defined and not as large as the pedicle of the human vertebra. Therefore, the position of the screw should be adapted to the pig and not merely transposed based on the literature on humans. The purpose of this study is to determine the characteristics of the optimum implantation corridors for pedicle screws in the thoracolumbar spine of piglets of different ages using computed tomography (CT and to determine the size and length of these corridors in pigs of different ages. CT scans from five groups of age: 6, 10, 14, 18, and 26 weeks were reviewed. For each thoracolumbar vertebrae, the pedicle width, pedicle axis length, and the pedicle angle was measured for the left and right pedicle. A total of 326 thoracic vertebrae and 126 lumbar vertebrae were included in the study. Pedicles are statistically larger but not longer for the lumbar vertebrae. An important variation of the pedicle angle is observed along the spine. In all pigs, an abrupt modification of the pedicle angle between T10 and T11 was observed, which corresponds to the level of the anticlinal vertebra which is the vertebra for which the spinous process is nearly perpendicular to the vertebral body. In conclusion, this study provides a quantitative database of pedicle screw implantation corridors in pigs of different ages. When using pedicle screws in experimental studies in pigs, these results should be considered for selecting the most suitable implants for the study but also to ensure a correct and safer screw position. Improving study procedures may limit postoperative complications and pain, thereby limiting the use of live animals.

  13. Safe corridor for the implantation of thoracolumbar pedicle screws in growing pigs: A morphometric study.

    Science.gov (United States)

    Cachon, Thibaut; Pillard, Paul; Odent, Thierry; Carozzo, Claude; Viguier, Eric

    2017-01-01

    The pig spine is widely used as a large animal model for preclinical research in human medicine to test new spinal implants and surgical procedures. Among them, pedicle screw is one of the most common method of fixation of those implants. However, the pedicle of the porcine vertebra is not as well defined and not as large as the pedicle of the human vertebra. Therefore, the position of the screw should be adapted to the pig and not merely transposed based on the literature on humans. The purpose of this study is to determine the characteristics of the optimum implantation corridors for pedicle screws in the thoracolumbar spine of piglets of different ages using computed tomography (CT) and to determine the size and length of these corridors in pigs of different ages. CT scans from five groups of age: 6, 10, 14, 18, and 26 weeks were reviewed. For each thoracolumbar vertebrae, the pedicle width, pedicle axis length, and the pedicle angle was measured for the left and right pedicle. A total of 326 thoracic vertebrae and 126 lumbar vertebrae were included in the study. Pedicles are statistically larger but not longer for the lumbar vertebrae. An important variation of the pedicle angle is observed along the spine. In all pigs, an abrupt modification of the pedicle angle between T10 and T11 was observed, which corresponds to the level of the anticlinal vertebra which is the vertebra for which the spinous process is nearly perpendicular to the vertebral body. In conclusion, this study provides a quantitative database of pedicle screw implantation corridors in pigs of different ages. When using pedicle screws in experimental studies in pigs, these results should be considered for selecting the most suitable implants for the study but also to ensure a correct and safer screw position. Improving study procedures may limit postoperative complications and pain, thereby limiting the use of live animals.

  14. Pullout strength of misplaced pedicle screws in the thoracic and lumbar vertebrae - A cadaveric study

    Directory of Open Access Journals (Sweden)

    Shyam K Saraf

    2013-01-01

    Full Text Available Background: The objective of this cadaveric study was to analyze the effects of iatrogenic pedicle perforations from screw misplacement on the mean pullout strength of lower thoracic and lumbar pedicle screws. We also investigated the effect of bone mineral density (BMD, diameter of pedicle screws, and the region of spine on the pullout strength of pedicle screws. Materials and Methods: Sixty fresh human cadaveric vertebrae (D10-L2 were harvested. Dual-energy X-ray absorptiometry (DEXA scan of vertebrae was done for BMD. Titanium pedicle screws of different diameters (5.2 and 6.2 mm were inserted in the thoracic and lumbar segments after dividing the specimens into three groups: a standard pedicle screw (no cortical perforation; b screw with medial cortical perforation; and c screw with lateral cortical perforation. Finally, pullout load of pedicle screws was recorded using INSTRON Universal Testing Machine. Results: Compared with standard placement, medially misplaced screws had 9.4% greater mean pullout strength and laterally misplaced screws had 47.3% lesser mean pullout strength. The pullout strength of the 6.2 mm pedicle screws was 33% greater than that of the 5.2 mm pedicle screws. The pullout load of pedicle screws in lumbar vertebra was 13.9% greater than that in the thoracic vertebra ( P = 0.105, but it was not statistically significant. There was no significant difference between pullout loads of vertebra with different BMD ( P = 0.901. Conclusion: The mean pullout strength was less with lateral misplaced pedicle screws while medial misplaced pedicle screw had more pullout strength. The pullout load of 6.2 mm screws was greater than that of 5.2 mm pedicle screws. No significant correlation was found between bone mineral densities and the pullout strength of vertebra. Similarly, the pullout load of screw placed in thoracic and lumbar vertebrae was not significantly different.

  15. Nonlinear dynamic systems identification using recurrent interval type-2 TSK fuzzy neural network - A novel structure.

    Science.gov (United States)

    El-Nagar, Ahmad M

    2017-10-31

    In this study, a novel structure of a recurrent interval type-2 Takagi-Sugeno-Kang (TSK) fuzzy neural network (FNN) is introduced for nonlinear dynamic and time-varying systems identification. It combines the type-2 fuzzy sets (T2FSs) and a recurrent FNN to avoid the data uncertainties. The fuzzy firing strengths in the proposed structure are returned to the network input as internal variables. The interval type-2 fuzzy sets (IT2FSs) is used to describe the antecedent part for each rule while the consequent part is a TSK-type, which is a linear function of the internal variables and the external inputs with interval weights. All the type-2 fuzzy rules for the proposed RIT2TSKFNN are learned on-line based on structure and parameter learning, which are performed using the type-2 fuzzy clustering. The antecedent and consequent parameters of the proposed RIT2TSKFNN are updated based on the Lyapunov function to achieve network stability. The obtained results indicate that our proposed network has a small root mean square error (RMSE) and a small integral of square error (ISE) with a small number of rules and a small computation time compared with other type-2 FNNs. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  16. Preschool externalizing behavior predicts gender-specific variation in adolescent neural structure.

    Directory of Open Access Journals (Sweden)

    Jessica Z K Caldwell

    Full Text Available Dysfunction in the prefrontal cortex, amygdala, and hippocampus is believed to underlie the development of much psychopathology. However, to date only limited longitudinal data relate early behavior with neural structure later in life. Our objective was to examine the relationship of early life externalizing behavior with adolescent brain structure. We report here the first longitudinal study linking externalizing behavior during preschool to brain structure during adolescence. We examined the relationship of preschool externalizing behavior with amygdala, hippocampus, and prefrontal cortex volumes at age 15 years in a community sample of 76 adolescents followed longitudinally since their mothers' pregnancy. A significant gender by externalizing behavior interaction revealed that males-but not females-with greater early childhood externalizing behavior had smaller amygdala volumes at adolescence (t = 2.33, p = .023. No significant results were found for the hippocampus or the prefrontal cortex. Greater early externalizing behavior also related to smaller volume of a cluster including the angular gyrus and tempoparietal junction across genders. Results were not attributable to the impact of preschool anxiety, preschool maternal stress, school-age internalizing or externalizing behaviors, or adolescent substance use. These findings demonstrate a novel, gender-specific relationship between early-childhood externalizing behavior and adolescent amygdala volume, as well as a cross-gender result for the angular gyrus and tempoparietal junction.

  17. Vertebral pedicle anatomy in relation to pedicle screw fixation: a cadaver study.

    Science.gov (United States)

    Chaynes, P; Sol, J C; Vaysse, P; Bécue, J; Lagarrigue, J

    2001-01-01

    New techniques to stabilize and correct the thoracic and lumbar spine have been developed in recent years. In view of the wide variety and complexity of fixation devices, the optimum configuration of spinal instrumentation systems needs to be defined. Linear and angular measurements of both vertebral pedicles were made in ten complete thoracic and lumbar cadaveric spines using callipers and a goniometer. The vertical interpedicular distance gradually increased along the spine up to L5. The transverse interpedicular distance was larger at both ends of the spine. Pedicular height gradually increased from T1 to L5, plateauing between T3 and T9, being widest at the thoracolumbar junction. Pedicular width was greatest at the three junctional regions of the spine. The sagittal pedicular angle decreased along the length of the spine to zero at L5. The transverse pedicular angle decreased from T1 to T12 and then increased to L5. Of the pedicular measurements only width limits the diameter of fixation screws. The vertical interpedicular distance determines the distance between the holes of plates, while the length of the transfixator is related to the transverse interpedicular distance. The pedicular angles enable triangulation of screws and determine the stability of the fixation.

  18. A "sling swing transposition" technique with pedicled dural flap for microvascular decompression in hemifacial spasm.

    Science.gov (United States)

    Khoo, Hui Ming; Yoshimine, Toshiki; Taki, Takuyu

    2012-09-01

    The key to successful microvascular decompression of the neurovascular compression syndrome is maintaining the separation between the nerve and the offending vessel. We describe a transposition technique in which a local pedicled dural flap, fashioned from the petrous posterior surface, is used to retract the offending vessel away from the root exit zone of the facial nerve in hemifacial spasm cases. We conducted a retrospective review of microvascular decompression operations in which the offending vessel was transposed and then retained by a local pedicled dural flap made from the dura of the petrous posterior surface. This technique was used in 7 consecutive cases of the most recently operated series. Postoperatively, complete symptom relief was achieved in 100% of the patients without any significant surgical complications. To our knowledge, this is the first report in which an autologous anatomic structure in the cerebellopontine angle, such as petrous dura mater, is used in the microvascular decompression of the facial nerve. This is a simple yet robust method and can be considered an option for the treatment of hemifacial spasm caused by arterial compression.

  19. The Effect of Position and Different Size of Radial Hole on Performance of Cannulated Pedicle Screw

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    Zakaria F. A.

    2017-01-01

    Full Text Available Cannulated Pedicle Screw (CPS is the instrumentation that has been introduced in Biomedical field in order to stabilize the spine structure and also to enhance the pullout strength in osteoporotic patient. The cement is injected through the CPS which is flow from the screw head to the radial hole and then distributed around the CPS to give higher performance of pullout strength. However, the fracture still reported to happened around the radial hole. This paper is aim to focus on the effect of the position and different diameter of radial hole on the CPS. Three designs were constructed using SolidWork software where two of it are the current models whereas the third was the proposed design which the radial holes were position differently (skewed to each other and its size is smaller than the current model, 1.0 mm and 1.5mm respectively. The software used for Finite Element Analysis (FEA is Ansys workbench 16.0. The Finite Element Models were verified with FEA result of the previous research. The FEA results of torsional stress for current and proposed design were then compared to obtain the maximum torque that both designs are able to resist before fracture. It can be concluded that the performance of CPS can be improved by the proposed design which is 2 radial hole skewed to each other and smaller radial hole diameter (1.0mm than the current cannulated pedicle screw (1.5mm.

  20. Metal artifacts reduction using monochromatic images from spectral CT: Evaluation of pedicle screws in patients with scoliosis

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    Wang, Yang, E-mail: wangzhang227@163.com [Department of Radiology, The Affiliated Nanjing Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008 (China); Qian, Bangping, E-mail: qianbangping@163.com [Spine Service, Drum Tower Hospital, Nanjing University Medical School, Nanjing 210008 (China); Li, Baoxin, E-mail: wangzhi68@163.com [Department of Radiology, The Affiliated Nanjing Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008 (China); Qin, Guochu, E-mail: qgc7605@yahoo.com.cn [Department of Radiology, The Affiliated Nanjing Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008 (China); Zhou, Zhengyang, E-mail: zyzhou@nju.edu.cn [Department of Radiology, The Affiliated Nanjing Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008 (China); Qiu, Yong, E-mail: scoliosis2002@sina.com [Spine Service, Drum Tower Hospital, Nanjing University Medical School, Nanjing 210008 (China); Sun, Xizhao, E-mail: sunxizhaonj@163.com [Department of Radiology and Urology, The Affiliated Nanjing Drum Tower Hospital of Nanjing University Medical School, No. 321 Zhongshan Road, Nanjing 210008 (China); Zhu, Bin, E-mail: gobin10266@163.com [Department of Radiology, The Affiliated Nanjing Drum Tower Hospital of Nanjing University Medical School, Nanjing 210008 (China)

    2013-08-15

    Purpose: To evaluate the effectiveness of spectral CT in reducing metal artifacts caused by pedicle screws in patients with scoliosis. Materials and methods: Institutional review committee approval and written informed consents from patients were obtained. 18 scoliotic patients with a total of 228 pedicle screws who underwent spectral CT imaging were included in this study. Monochromatic image sets with and without the additional metal artifacts reduction software (MARS) correction were generated with photon energy at 65 keV and from 70 to 140 keV with 10 keV interval using the 80 kVp and 140 kVp projection sets. Polychromatic images corresponded to the conventional 140 kVp imaging were also generated from the same scan data as a control group. Both objective evaluation (screw width and quantitative artifacts index measurements) and subjective evaluation (depiction of pedicle screws, surrounding structures and their relationship) were performed. Results: Image quality of monochromatic images in the range from 110 to 140 keV (0.97 ± 0.28) was rated superior to the conventional polychromatic images (2.53 ± 0.54) and also better than monochromatic images with lower energy. Images of energy above 100 keV also give accurate measurement of the width of screws and relatively low artifacts index. The form of screws was slightly distorted in MARS reconstruction. Conclusions: Compared to conventional polychromatic images, monochromatic images acquired from dual-energy CT provided superior image quality with much reduced metal artifacts of pedicle screws in patients with scoliosis. Optimal energy range was found between 110 and 140 keV.

  1. Computed tomography assessment of lateral pedicle wall perforation by free-hand subaxial cervical pedicle screw placement.

    Science.gov (United States)

    Wang, Yingsong; Xie, Jingming; Yang, Zhendong; Zhao, Zhi; Zhang, Ying; Li, Tao; Liu, Luping

    2013-07-01

    To present the technique of free-hand subaxial cervical pedicle screw (CPS) placement without using intra-operative navigating devices, and to investigate the crucial factors for safe placement and avoidance of lateral pedicle wall perforation, by measuring and classifying perforations with postoperative computed tomography (CT) scan. The placement of CPS has generally been considered as technically demanding and associated with considerable lateral wall perforation rate. For surgeons without access to navigation systems, experience of safe free-hand technique for subaxial CPS placement is especially valuable. A total of 214 consecutive traumatic or degenerative patients with 1,024 CPS placement using the free-hand technique were enrolled. In the operative process, the lateral mass surface was decorticated. Then a small curette was used to identify the pedicle entrance by touching the cortical bone of the medial pedicle wall. It was crucial to keep the transverse angle and make appropriate adjustment with guidance of the resistance of the thick medial cortical bone. The hand drill should be redirected once soft tissue breach was palpated by a slim ball-tip prober. With proper trajectory, tapping, repeated palpation, the 26-30 mm screw could be placed. After the procedure, the transverse angle of CPS trajectory was measured, and perforation of the lateral wall was classified by CT scan: grade 1, perforation of pedicle wall by screw placement, with the external edge of screw deviating out of the lateral pedicle wall equal to or less than 2 mm and grade 2, critical perforation of pedicle wall by screw placement, large than 2 mm. A total of 129 screws (12.64 %) were demonstrated as lateral pedicle wall perforation, of which 101 screws (9.86 %) were classified as grade 1, whereas 28 screws (2.73 %) as grade 2. Among the segments involved, C3 showed an obviously higher perforating rate than other (P grade 2 perforation than the others. In the 28 screws of grade 2

  2. Is There Asymmetry Between the Concave and Convex Pedicles in Adolescent Idiopathic Scoliosis? A CT Investigation.

    Science.gov (United States)

    Davis, Colin M; Grant, Caroline A; Pearcy, Mark J; Askin, Geoffrey N; Labrom, Robert D; Izatt, Maree T; Adam, Clayton J; Little, J Paige

    2017-03-01

    Adolescent idiopathic scoliosis is a complex three-dimensional deformity of the spine characterized by deformities in the sagittal, coronal, and axial planes. Spinal fusion using pedicle screw instrumentation is a widely used method for surgical correction in severe (coronal deformity, Cobb angle > 45°) adolescent idiopathic scoliosis curves. Understanding the anatomic difference in the pedicles of patients with adolescent idiopathic scoliosis is essential to reduce the risk of neurovascular or visceral injury through pedicle screw misplacement. To use CT scans (1) to analyze pedicle anatomy in the adolescent thoracic scoliotic spine comparing concave and convex pedicles and (2) to assess the intra- and interobserver reliability of these measurements to provide critical information to spine surgeons regarding size, length, and angle of projection. Between 2007 and 2009, 27 patients with adolescent idiopathic scoliosis underwent thoracoscopic anterior correction surgery by two experienced spinal surgeons. Preoperatively, each patient underwent a CT scan as was their standard of care at that time. Twenty-two patients (mean age, 15.7 years; SD, 2.4 years; range, 11.6-22 years) (mean Cobb angle, 53°; SD, 5.3°; range, 42°-63°) were selected. Inclusion criteria were a clinical diagnosis of adolescent idiopathic scoliosis, female, and Lenke type 1 adolescent idiopathic scoliosis with the major curve confined to the thoracic spine. Using three-dimensional image analysis software, the pedicle width, inner cortical pedicle width, pedicle height, inner cortical pedicle height, pedicle length, chord length, transverse pedicle angle, and sagittal pedicle angles were measured. Randomly selected scans were remeasured by two of the authors and the reproducibility of the measurement definitions was validated through limit of agreement analysis. The concave pedicle widths were smaller compared with the convex pedicle widths at T7, T8, and T9 by 37% (3.44 mm ± 1.16 mm vs 4

  3. Structural basis for cholinergic regulation of neural circuits in the mouse olfactory bulb.

    Science.gov (United States)

    Hamamoto, Masakazu; Kiyokage, Emi; Sohn, Jaerin; Hioki, Hiroyuki; Harada, Tamotsu; Toida, Kazunori

    2017-02-15

    Odor information is regulated by olfactory inputs, bulbar interneurons, and centrifugal inputs in the olfactory bulb (OB). Cholinergic neurons projecting from the nucleus of the horizontal limb of the diagonal band of Broca and the magnocellular preoptic nucleus are one of the primary centrifugal inputs to the OB. In this study, we focused on cholinergic regulation of the OB and analyzed neural morphology with a particular emphasis on the projection pathways of cholinergic neurons. Single-cell imaging of a specific neuron within dense fibers is critical to evaluate the structure and function of the neural circuits. We labeled cholinergic neurons by infection with virus vector and then reconstructed them three-dimensionally. We also examined the ultramicrostructure of synapses by electron microscopy tomography. To further clarify the function of cholinergic neurons, we performed confocal laser scanning microscopy to investigate whether other neurotransmitters are present within cholinergic axons in the OB. Our results showed the first visualization of complete cholinergic neurons, including axons projecting to the OB, and also revealed frequent axonal branching within the OB where it innervated multiple glomeruli in different areas. Furthermore, electron tomography demonstrated that cholinergic axons formed asymmetrical synapses with a morphological variety of thicknesses of the postsynaptic density. Although we have not yet detected the presence of other neurotransmitters, the range of synaptic morphology suggests multiple modes of transmission. The present study elucidates the ways that cholinergic neurons could contribute to the elaborate mechanisms involved in olfactory processing in the OB. J. Comp. Neurol. 525:574-591, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  4. Sensory-related neural activity regulates the structure of vascular networks in the cerebral cortex

    Science.gov (United States)

    Lacoste, Baptiste; Comin, Cesar H.; Ben-Zvi, Ayal; Kaeser, Pascal S.; Xu, Xiaoyin; Costa, Luciano da F.; Gu, Chenghua

    2014-01-01

    SUMMARY Neurovascular interactions are essential for proper brain function. While the effect of neural activity on cerebral blood flow has been extensively studied, whether neural activity influences vascular patterning remains elusive. Here, we demonstrate that neural activity promotes the formation of vascular networks in the early postnatal mouse barrel cortex. Using a combination of genetics, imaging, and computational tools to allow simultaneous analysis of neuronal and vascular components, we found that vascular density and branching were decreased in the barrel cortex when sensory input was reduced by either a complete deafferentation, a genetic impairment of neurotransmitter release at thalamocortical synapses, or a selective reduction of sensory-related neural activity by whisker plucking. In contrast, enhancement of neural activity by whisker stimulation led to an increase in vascular density and branching. The finding that neural activity is necessary and sufficient to trigger alterations of vascular networks reveals a novel feature of neurovascular interactions. PMID:25155955

  5. Sensory-related neural activity regulates the structure of vascular networks in the cerebral cortex.

    Science.gov (United States)

    Lacoste, Baptiste; Comin, Cesar H; Ben-Zvi, Ayal; Kaeser, Pascal S; Xu, Xiaoyin; Costa, Luciano da F; Gu, Chenghua

    2014-09-03

    Neurovascular interactions are essential for proper brain function. While the effect of neural activity on cerebral blood flow has been extensively studied, whether or not neural activity influences vascular patterning remains elusive. Here, we demonstrate that neural activity promotes the formation of vascular networks in the early postnatal mouse barrel cortex. Using a combination of genetics, imaging, and computational tools to allow simultaneous analysis of neuronal and vascular components, we found that vascular density and branching were decreased in the barrel cortex when sensory input was reduced by either a complete deafferentation, a genetic impairment of neurotransmitter release at thalamocortical synapses, or a selective reduction of sensory-related neural activity by whisker plucking. In contrast, enhancement of neural activity by whisker stimulation led to an increase in vascular density and branching. The finding that neural activity is necessary and sufficient to trigger alterations of vascular networks reveals an important feature of neurovascular interactions. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Use of Pedicled Buccal Fat Pad for Cranial Base Reconstruction.

    Science.gov (United States)

    Gadre, Pushkar; Ghadge, Murarji Tanaji; Singh, Divya; Gadre, Kiran

    2017-03-01

    Craniofacial reconstruction for closure of skull base defects after removal of anterior cranial base lesions is challenging. Persistent skull base defect produces extremely high risk of cerebrospinal fluid leaks and consecutive infectious complications. The authors' article focuses on the use of pedicled buccal fat pad for the reconstruction of anterior cranial base defects using combined endoscope-assisted approach and Lefort I access osteotomy. High effectiveness and minimal invasiveness are principal advantages of the technique. Other benefits include proximity of donor site to defect, simplicity of surgical technique, minimal postoperative discomfort, and very low risk of benign complications. Local pedicled grafts are the preferred material for plasty, adding aesthetic results in an ablative surgery using intraoral incision and access osteotomy. Thus, the technique solves the problem of relying on complex alloplastic reconstruction of anterior craniobasal defects.

  7. A Damage Prognosis Method of Girder Structures Based on Wavelet Neural Networks

    Directory of Open Access Journals (Sweden)

    Rumian Zhong

    2014-01-01

    Full Text Available Based on the basic theory of wavelet neural networks and finite element model updating method, a basic framework of damage prognosis method is proposed in this paper. Firstly, a damaged I-steel beam model testing is used to verify the feasibility and effectiveness of the proposed damage prognosis method. The results show that the predicted results of the damage prognosis method and the measured results are very well consistent, and the maximum error is less than 5%. Furthermore, Xinyihe Bridge in the Beijing-Shanghai Highway is selected as the engineering background, and the damage prognosis is conducted based on the data from the structural health monitoring system. The results show that the traffic volume will increase and seasonal differences will decrease in the next year and a half. The displacement has a slight increase and seasonal characters in the critical section of mid span, but the strain will increase distinctly. The analysis results indicate that the proposed method can be applied to the damage prognosis of girder bridge structures and has the potential for the bridge health monitoring and safety prognosis.

  8. Frontal Structural Neural Correlates of Working Memory Performance in Older Adults

    Science.gov (United States)

    Nissim, Nicole R.; O’Shea, Andrew M.; Bryant, Vaughn; Porges, Eric C.; Cohen, Ronald; Woods, Adam J.

    2017-01-01

    Working memory is an executive memory process that allows transitional information to be held and manipulated temporarily in memory stores before being forgotten or encoded into long-term memory. Working memory is necessary for everyday decision-making and problem solving, making it a fundamental process in the daily lives of older adults. Working memory relies heavily on frontal lobe structures and is known to decline with age. The current study aimed to determine the neural correlates of decreased working memory performance in the frontal lobes by comparing cortical thickness and cortical surface area from two demographically matched groups of healthy older adults, free from cognitive impairment, with high versus low N-Back working memory performance (N = 56; average age = 70.29 ± 10.64). High-resolution structural T1-weighted images (1 mm isotropic voxels) were obtained on a 3T Philips MRI scanner. When compared to high performers, low performers exhibited significantly decreased cortical surface area in three frontal lobe regions lateralized to the right hemisphere: medial orbital frontal gyrus, inferior frontal gyrus, and superior frontal gyrus (FDR p working memory function. PMID:28101053

  9. BrainSegNet: a convolutional neural network architecture for automated segmentation of human brain structures.

    Science.gov (United States)

    Mehta, Raghav; Majumdar, Aabhas; Sivaswamy, Jayanthi

    2017-04-01

    Automated segmentation of cortical and noncortical human brain structures has been hitherto approached using nonrigid registration followed by label fusion. We propose an alternative approach for this using a convolutional neural network (CNN) which classifies a voxel into one of many structures. Four different kinds of two-dimensional and three-dimensional intensity patches are extracted for each voxel, providing local and global (context) information to the CNN. The proposed approach is evaluated on five different publicly available datasets which differ in the number of labels per volume. The obtained mean Dice coefficient varied according to the number of labels, for example, it is [Formula: see text] and [Formula: see text] for datasets with the least (32) and the most (134) number of labels, respectively. These figures are marginally better or on par with those obtained with the current state-of-the-art methods on nearly all datasets, at a reduced computational time. The consistently good performance of the proposed method across datasets and no requirement for registration make it attractive for many applications where reduced computational time is necessary.

  10. Demystifying Multitask Deep Neural Networks for Quantitative Structure-Activity Relationships.

    Science.gov (United States)

    Xu, Yuting; Ma, Junshui; Liaw, Andy; Sheridan, Robert P; Svetnik, Vladimir

    2017-10-23

    Deep neural networks (DNNs) are complex computational models that have found great success in many artificial intelligence applications, such as computer vision1,2 and natural language processing.3,4 In the past four years, DNNs have also generated promising results for quantitative structure-activity relationship (QSAR) tasks.5,6 Previous work showed that DNNs can routinely make better predictions than traditional methods, such as random forests, on a diverse collection of QSAR data sets. It was also found that multitask DNN models-those trained on and predicting multiple QSAR properties simultaneously-outperform DNNs trained separately on the individual data sets in many, but not all, tasks. To date there has been no satisfactory explanation of why the QSAR of one task embedded in a multitask DNN can borrow information from other unrelated QSAR tasks. Thus, using multitask DNNs in a way that consistently provides a predictive advantage becomes a challenge. In this work, we explored why multitask DNNs make a difference in predictive performance. Our results show that during prediction a multitask DNN does borrow "signal" from molecules with similar structures in the training sets of the other tasks. However, whether this borrowing leads to better or worse predictive performance depends on whether the activities are correlated. On the basis of this, we have developed a strategy to use multitask DNNs that incorporate prior domain knowledge to select training sets with correlated activities, and we demonstrate its effectiveness on several examples.

  11. Neural correlates and structural markers of emotion dysregulation in traumatized civilians

    Science.gov (United States)

    Stevens, Jennifer S.; van Rooij, Sanne J.H.; Ely, Timothy D.; Fani, Negar; Jovanovic, Tanja; Ressler, Kerry J.; Bradley, Bekh

    2017-01-01

    Abstract Emotion dysregulation (ED) reflects deficits in understanding and managing negative emotions and may serve as a transdiagnostic mechanism of risk for trauma-related psychiatric disorders. Therefore, understanding neurobiological substrates of ED in traumatized individuals is critical. The present study examined associations between ED and baseline structural differences and patterns of functional activity during an emotional task in a sample of African American women (n = 136) recruited from an urban hospital. Participants engaged in a structural magnetic resonance imaging (MRI) session. A subsample (n = 92) also viewed emotional face stimuli during functional MRI. ED was related to greater dorsal anterior cingulate cortex (dACC) surface area (Pcorr < 0.05) and increased dorsomedial prefrontal cortex (dmPFC) and ventromedial PFC activation to fearful stimuli (Pcorr < 0.05), independent of the trauma and psychiatric symptoms. DMPFC activation was also associated with posttraumatic stress disorder and depression symptoms. Mediation analyses showed a significant mediation effect of ED on the relation between dmPFC activation and psychiatric symptoms. These findings are important since dACC and dmPFC play central roles in fear expression and attention to emotional stimuli. Future longitudinal research is needed to help solidify a model of risk for how such neural substrates may be impacted by traumatic experiences to create ED. PMID:28158800

  12. Inverse analysis of aerodynamic loads from strain information using structural models and neural networks

    Science.gov (United States)

    Wada, Daichi; Sugimoto, Yohei

    2017-04-01

    Aerodynamic loads on aircraft wings are one of the key parameters to be monitored for reliable and effective aircraft operations and management. Flight data of the aerodynamic loads would be used onboard to control the aircraft and accumulated data would be used for the condition-based maintenance and the feedback for the fatigue and critical load modeling. The effective sensing techniques such as fiber optic distributed sensing have been developed and demonstrated promising capability of monitoring structural responses, i.e., strains on the surface of the aircraft wings. By using the developed techniques, load identification methods for structural health monitoring are expected to be established. The typical inverse analysis for load identification using strains calculates the loads in a discrete form of concentrated forces, however, the distributed form of the loads is essential for the accurate and reliable estimation of the critical stress at structural parts. In this study, we demonstrate an inverse analysis to identify the distributed loads from measured strain information. The introduced inverse analysis technique calculates aerodynamic loads not in a discrete but in a distributed manner based on a finite element model. In order to verify the technique through numerical simulations, we apply static aerodynamic loads on a flat panel model, and conduct the inverse identification of the load distributions. We take two approaches to build the inverse system between loads and strains. The first one uses structural models and the second one uses neural networks. We compare the performance of the two approaches, and discuss the effect of the amount of the strain sensing information.

  13. Revisiting the Neural Basis of Acquired Amusia: Lesion Patterns and Structural Changes Underlying Amusia Recovery

    Directory of Open Access Journals (Sweden)

    Aleksi J. Sihvonen

    2017-07-01

    Full Text Available Although, acquired amusia is a common deficit following stroke, relatively little is still known about its precise neural basis, let alone to its recovery. Recently, we performed a voxel-based lesion-symptom mapping (VLSM and morphometry (VBM study which revealed a right lateralized lesion pattern, and longitudinal gray matter volume (GMV and white matter volume (WMV changes that were specifically associated with acquired amusia after stroke. In the present study, using a larger sample of stroke patients (N = 90, we aimed to replicate and extend the previous structural findings as well as to determine the lesion patterns and volumetric changes associated with amusia recovery. Structural MRIs were acquired at acute and 6-month post-stroke stages. Music perception was behaviorally assessed at acute and 3-month post-stroke stages using the Scale and Rhythm subtests of the Montreal Battery of Evaluation of Amusia (MBEA. Using these scores, the patients were classified as non-amusic, recovered amusic, and non-recovered amusic. The results of the acute stage VLSM analyses and the longitudinal VBM analyses converged to show that more severe and persistent (non-recovered amusia was associated with an extensive pattern of lesions and GMV/WMV decrease in right temporal, frontal, parietal, striatal, and limbic areas. In contrast, less severe and transient (recovered amusia was linked to lesions specifically in left inferior frontal gyrus as well as to a GMV decrease in right parietal areas. Separate continuous analyses of MBEA Scale and Rhythm scores showed extensively overlapping lesion pattern in right temporal, frontal, and subcortical structures as well as in the right insula. Interestingly, the recovered pitch amusia was related to smaller GMV decreases in the temporoparietal junction whereas the recovered rhythm amusia was associated to smaller GMV decreases in the inferior temporal pole. Overall, the results provide a more comprehensive picture of

  14. [Vascular pedicle elongation technique in anterolateral thigh island flap transplantation].

    Science.gov (United States)

    Wang, Chiyu; Kang, Qinglin; Song, Wenqi

    2007-12-01

    To introduce a new technique for vascular pedicle elongation in the anterolateral thigh island flap transplantation and evaluate the outcome of this technique in the clinical application. From January 2003 to January 2006, 6 patients (5 males, 1 female; age, 18-49 years) were admitted for surgical operation because of the soft tissue defect around the knee joint. The soft tissue defect after the injury was found in 3 patients, the defect after the removal of the soft-tissue tumor in 1, and the defect after the prosthetic replacement in the knee joint in 2. The soft tissue defects ranged in size of 8 cm x 4 cm to 15 cm x 6 cm. When the anterolateral island flap of the thigh underwent the reverse transplantation, the ascending branch of the lateral circumflex femoral artery was used as a nutrient vessel for the flap, and the descending branch of the lateral circumflex femoral artery was separated to the distal part. The main trunk of the lateral circumflex femoral artery was ligated at the point that was proximal to the furcation of the ascending and decending branches so that the vessel pedicle of the flap could be lengthened and then the defect was repaired. The flaps ranged in size of 10 cm x 6 cm to 18 cm x 8 cm. All the flaps were successfully transferred in the 6 patients. The lengthened pedicle ranged in length from 8 to 12 cm, with an average of 10 cm. There was no vascular crisis after operation. All the transferred flaps survived, with a color and texture similar to those in the recipient site. The postoperative follow-up for 6-18 months revealed that the motion range of the knees was satisfactory. The vascular pedicle elongation technique can enlarge the application scope of the anterolateral thigh island flap and the survival rate of the flap is not influenced by any factor.

  15. PEDICLE TONGUE FLAP SURGERY IN ORAL SUBMUCOUS FIBROSIS

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    Muthubabu K

    2016-09-01

    Full Text Available BACKGROUND Oral submucous fibrosis is a disease of unknown aetiology and is a legacy of Indians. It has been variously treated both medically and surgically but neither has been found to be rewarding. Various groups have been studying the therapy schedules and aetiological association, but the conclusions have remained unclear. AIM The study aims to focus on newer surgical therapy stressing on the mechanics and use of pedicle tongue flap in the management of this condition. METHODS AND MATERIALS The study comprised of 40 patients from our outpatient department suffering from oral submucous fibrosis in the age group of 11 to 70 years. The contributory factors of oral submucous fibrosis and the symptoms of the disease were evaluated and the role of pedicle tongue flap surgery in the management of this disease which is a premalignant condition is discussed. RESULTS AND CONCLUSION Pedicle tongue flap surgery has given promising results in the treatment of trismus due to oral submucous fibrosis. After the surgery, none of our patients developed any malignant change.

  16. Capturing multidimensionality in stroke aphasia: mapping principal behavioural components to neural structures.

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    Butler, Rebecca A; Lambon Ralph, Matthew A; Woollams, Anna M

    2014-12-01

    Stroke aphasia is a multidimensional disorder in which patient profiles reflect variation along multiple behavioural continua. We present a novel approach to separating the principal aspects of chronic aphasic performance and isolating their neural bases. Principal components analysis was used to extract core factors underlying performance of 31 participants with chronic stroke aphasia on a large, detailed battery of behavioural assessments. The rotated principle components analysis revealed three key factors, which we labelled as phonology, semantic and executive/cognition on the basis of the common elements in the tests that loaded most strongly on each component. The phonology factor explained the most variance, followed by the semantic factor and then the executive-cognition factor. The use of principle components analysis rendered participants' scores on these three factors orthogonal and therefore ideal for use as simultaneous continuous predictors in a voxel-based correlational methodology analysis of high resolution structural scans. Phonological processing ability was uniquely related to left posterior perisylvian regions including Heschl's gyrus, posterior middle and superior temporal gyri and superior temporal sulcus, as well as the white matter underlying the posterior superior temporal gyrus. The semantic factor was uniquely related to left anterior middle temporal gyrus and the underlying temporal stem. The executive-cognition factor was not correlated selectively with the structural integrity of any particular region, as might be expected in light of the widely-distributed and multi-functional nature of the regions that support executive functions. The identified phonological and semantic areas align well with those highlighted by other methodologies such as functional neuroimaging and neurostimulation. The use of principle components analysis allowed us to characterize the neural bases of participants' behavioural performance more robustly and

  17. Capturing multidimensionality in stroke aphasia: mapping principal behavioural components to neural structures

    Science.gov (United States)

    Butler, Rebecca A.

    2014-01-01

    Stroke aphasia is a multidimensional disorder in which patient profiles reflect variation along multiple behavioural continua. We present a novel approach to separating the principal aspects of chronic aphasic performance and isolating their neural bases. Principal components analysis was used to extract core factors underlying performance of 31 participants with chronic stroke aphasia on a large, detailed battery of behavioural assessments. The rotated principle components analysis revealed three key factors, which we labelled as phonology, semantic and executive/cognition on the basis of the common elements in the tests that loaded most strongly on each component. The phonology factor explained the most variance, followed by the semantic factor and then the executive-cognition factor. The use of principle components analysis rendered participants’ scores on these three factors orthogonal and therefore ideal for use as simultaneous continuous predictors in a voxel-based correlational methodology analysis of high resolution structural scans. Phonological processing ability was uniquely related to left posterior perisylvian regions including Heschl’s gyrus, posterior middle and superior temporal gyri and superior temporal sulcus, as well as the white matter underlying the posterior superior temporal gyrus. The semantic factor was uniquely related to left anterior middle temporal gyrus and the underlying temporal stem. The executive-cognition factor was not correlated selectively with the structural integrity of any particular region, as might be expected in light of the widely-distributed and multi-functional nature of the regions that support executive functions. The identified phonological and semantic areas align well with those highlighted by other methodologies such as functional neuroimaging and neurostimulation. The use of principle components analysis allowed us to characterize the neural bases of participants’ behavioural performance more robustly and

  18. A place for time: the spatiotemporal structure of neural dynamics during natural audition

    NARCIS (Netherlands)

    Stephens, G.J.; Honey, C.J.; Hasson, U.

    2013-01-01

    We use functional magnetic resonance imaging (fMRI) to analyze neural responses to natural auditory stimuli. We characterize the fMRI time series through the shape of the voxel power spectrum and find that the timescales of neural dynamics vary along a spatial gradient, with faster dynamics in early

  19. Pedicle screw fixation with kyphoplasty decreases the fracture risk of the treated and adjacent non-treated vertebral bodies: a finite element analysis.

    Science.gov (United States)

    Yang, Pan; Zhang, Ying; Ding, Huan-Wen; Liu, Jian; Ye, Lin-Qiang; Xiao, Jin; Tu, Qiang; Yang, Tao; Wang, Fei; Sun, Guo-Gang

    2016-12-01

    Adjacent vertebral fractures are common in patients with osteoporotic vertebral compression fractures (OVCFs) after kyphoplasty. This finite element study was to examine whether short segment pedicle screw fixation (PSF) with kyphoplasty may decrease the fracture risk of the treated and adjacent non-treated vertebrae after kyphoplasty for OVCFs. By simulating cement augmentation with or without short segment pedicle screw fixation (PSF), two tridimensional, anatomically detailed finite element models of the T10-L2 functional spinal junction were developed. The insertion of pedicle screws into the intact vertebra apparently decreased the stress distribution of the treated vertebra in vertical compression and other load situations. The stress distribution in the bone structures of the intact vertebra adjacent to the intact-screwed vertebra was much less than that in the one adjacent to the treated vertebra. The insertion of pedicle screws into the intact vertebra greatly decreased the maximum displacement of the cortical bones and cancellous bones of the vertebrae. Our results indicated that short segment PSF with kyphoplasty may decrease the fracture risk of the treated and adjacent non-treated vertebrae in the management of OVCFs.

  20. The biomechanics of pedicle screw augmentation with cement.

    Science.gov (United States)

    Elder, Benjamin D; Lo, Sheng-Fu L; Holmes, Christina; Goodwin, Courtney R; Kosztowski, Thomas A; Lina, Ioan A; Locke, John E; Witham, Timothy F

    2015-06-01

    A persistent challenge in spine surgery is improving screw fixation in patients with poor bone quality. Augmenting pedicle screw fixation with cement appears to be a promising approach. The purpose of this study was to survey the literature and assess the previous biomechanical studies on pedicle screw augmentation with cement to provide in-depth discussions of the biomechanical benefits of multiple parameters in screw augmentation. This is a systematic literature review. A search of Medline was performed, combining search terms of pedicle screw, augmentation, vertebroplasty, kyphoplasty, polymethylmethacrylate, calcium phosphate, or calcium sulfate. The retrieved articles and their references were reviewed, and articles dealing with biomechanical testing were included in this article. Polymethylmethacrylate is an effective material for enhancing pedicle screw fixation in both osteoporosis and revision spine surgery models. Several other calcium ceramics also appear promising, although further work is needed in material development. Although fenestrated screw delivery appears to have some benefits, it results in similar screw fixation to prefilling the cement with a solid screw. Some differences in screw biomechanics were noted with varying cement volume and curing time, and some benefits from a kyphoplasty approach over a vertebroplasty approach have been noted. Additionally, in cadaveric models, cemented-augmented screws were able to be removed, albeit at higher extraction torques, without catastrophic damage to the vertebral body. However, there is a risk of cement extravasation leading to potentially neurological or cardiovascular complications with cement use. A major limitation of these reviewed studies is that biomechanical tests were generally performed at screw implantation or after a limited cyclic loading cycle; thus, the results may not be entirely clinically applicable. This is particularly true in the case of the bioactive calcium ceramics, as these

  1. Comparison between posterior lumbar fusion with pedicle screws and posterior lumbar interbody fusion with pedicle screws in adult spondylolisthesis.

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    Dantas, Fernando Luiz Rolemberg; Prandini, Mirto Nelso; Ferreira, Mauro A T

    2007-09-01

    The purpose of this study was to compare patients with lumbar spondylolisthesis submitted to two different surgical approaches, and evaluate the results and outcomes in both groups. In a two-year period, 60 adult patients with lumbar spondylolisthesis, both isthmic and degenerative, were submitted to surgery at the Biocor Institute, Brazil. All patients were operated on by the same surgeon (FLRD) in a single institution, and the results were analyzed prospectively. Group I comprised the first 30 consecutive patients that were submitted to a posterior lumbar spinal fusion with pedicle screws (PLF). Group II comprised the last 30 consecutive patients submitted to a posterior lumbar interbody fusion procedure (PLIF) with pedicle screws. All patients underwent foraminotomy for nerve root decompression. Clinical evaluation was carried out using the Prolo Economic and Functional Scale and the Rolland-Morris and the Oswestry questionnaire. Mean age was 52.4 for Group I (PLF), and 47.6 for Group II (PLIF). The mean follow-up was 3.2 years. Both surgical procedures were effective. The PLIF with pedicle screws group presented better clinical outcomes. Group I presented more complications when compared with Group II. Group II presented better results as indicated in the Prolo Economic and Functional Scale.

  2. Feature Selection Combined with Neural Network Structure Optimization for HIV-1 Protease Cleavage Site Prediction

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    Hui Liu

    2015-01-01

    Full Text Available It is crucial to understand the specificity of HIV-1 protease for designing HIV-1 protease inhibitors. In this paper, a new feature selection method combined with neural network structure optimization is proposed to analyze the specificity of HIV-1 protease and find the important positions in an octapeptide that determined its cleavability. Two kinds of newly proposed features based on Amino Acid Index database plus traditional orthogonal encoding features are used in this paper, taking both physiochemical and sequence information into consideration. Results of feature selection prove that p2, p1, p1′, and p2′ are the most important positions. Two feature fusion methods are used in this paper: combination fusion and decision fusion aiming to get comprehensive feature representation and improve prediction performance. Decision fusion of subsets that getting after feature selection obtains excellent prediction performance, which proves feature selection combined with decision fusion is an effective and useful method for the task of HIV-1 protease cleavage site prediction. The results and analysis in this paper can provide useful instruction and help designing HIV-1 protease inhibitor in the future.

  3. Feature Selection Combined with Neural Network Structure Optimization for HIV-1 Protease Cleavage Site Prediction.

    Science.gov (United States)

    Liu, Hui; Shi, Xiaomiao; Guo, Dongmei; Zhao, Zuowei; Yimin

    2015-01-01

    It is crucial to understand the specificity of HIV-1 protease for designing HIV-1 protease inhibitors. In this paper, a new feature selection method combined with neural network structure optimization is proposed to analyze the specificity of HIV-1 protease and find the important positions in an octapeptide that determined its cleavability. Two kinds of newly proposed features based on Amino Acid Index database plus traditional orthogonal encoding features are used in this paper, taking both physiochemical and sequence information into consideration. Results of feature selection prove that p2, p1, p1', and p2' are the most important positions. Two feature fusion methods are used in this paper: combination fusion and decision fusion aiming to get comprehensive feature representation and improve prediction performance. Decision fusion of subsets that getting after feature selection obtains excellent prediction performance, which proves feature selection combined with decision fusion is an effective and useful method for the task of HIV-1 protease cleavage site prediction. The results and analysis in this paper can provide useful instruction and help designing HIV-1 protease inhibitor in the future.

  4. The neural substrates of complex argument structure representations: Processing 'alternating transitivity' verbs.

    Science.gov (United States)

    Meltzer-Asscher, Aya; Schuchard, Julia; den Ouden, Dirk-Bart; Thompson, Cynthia K

    This study examines the neural correlates of processing verbal entries with multiple argument structures using fMRI. We compared brain activation in response to 'alternating transitivity' verbs, corresponding to two different verbal alternates - one transitive and one intransitive - and simple verbs, with only one, intransitive, thematic grid. Fourteen young healthy participants performed a lexical decision task with the two verb types. Results showed significantly greater activation in the angular and supramarginal gyri (BAs 39 and 40) extending to the posterior superior and middle temporal gyri bilaterally, for alternating compared to simple verbs. Additional activation was detected in bilateral middle and superior frontal gyri (BAs 8 and 9). The opposite contrast, simple compared to alternating verbs, showed no significant differential activation in any regions of the brain. These findings are consistent with previous studies implicating a posterior network including the superior temporal, supramarginal and angular gyri for processing verbs with multiple thematic roles, as well as with those suggesting involvement of the middle and superior frontal gyri in lexical ambiguity processing. However, because 'alternating transitivity' verbs differ from simple intransitives with regard to both the number of thematic grids (two vs. one) and the number of thematic roles (two vs. one), our findings do not distinguish between activations associated with these two differences.

  5. The neural substrates of complex argument structure representations: Processing ‘alternating transitivity’ verbs

    Science.gov (United States)

    Meltzer-Asscher, Aya; Schuchard, Julia; den Ouden, Dirk-Bart; Thompson, Cynthia K.

    2015-01-01

    This study examines the neural correlates of processing verbal entries with multiple argument structures using fMRI. We compared brain activation in response to ‘alternating transitivity’ verbs, corresponding to two different verbal alternates – one transitive and one intransitive - and simple verbs, with only one, intransitive, thematic grid. Fourteen young healthy participants performed a lexical decision task with the two verb types. Results showed significantly greater activation in the angular and supramarginal gyri (BAs 39 and 40) extending to the posterior superior and middle temporal gyri bilaterally, for alternating compared to simple verbs. Additional activation was detected in bilateral middle and superior frontal gyri (BAs 8 and 9). The opposite contrast, simple compared to alternating verbs, showed no significant differential activation in any regions of the brain. These findings are consistent with previous studies implicating a posterior network including the superior temporal, supramarginal and angular gyri for processing verbs with multiple thematic roles, as well as with those suggesting involvement of the middle and superior frontal gyri in lexical ambiguity processing. However, because ‘alternating transitivity’ verbs differ from simple intransitives with regard to both the number of thematic grids (two vs. one) and the number of thematic roles (two vs. one), our findings do not distinguish between activations associated with these two differences. PMID:26139954

  6. Artificial neural network prediction of quantitative structure - retention relationships of polycyclic aromatic hydocarbons in gas chromatography

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    SNEZANA SREMAC

    2005-11-01

    Full Text Available A feed-forward artificial neural network (ANN model was used to link molecular structures (boiling points, connectivity indices and molecular weights and retention indices of polycyclic aromatic hydrocarbons (PAHs in linear temperature-programmed gas chromatography. A randomly taken subset of PAH retention data reported by Lee et al. [Anal. Chem. 51 (1979 768], containing retention index data for 30 PAHs, was used to make the ANN model. The prediction ability of the trained ANN was tested on unseen data for 18 PAHs from the same article, as well as on the retention data for 7 PAHs experimentally obtained in this work. In addition, two different data sets with known retention indices taken from the literature were analyzed by the same ANN model. It has been shown that the relative accuracy as the degree of agreement between the measured and the predicted retention indices in all testing sets, for most of the studied PAHs, were within the experimental error margins (±3%.

  7. Placement of thoracic transvertebral pedicle screws using 3D image guidance.

    Science.gov (United States)

    Nottmeier, Eric W; Pirris, Stephen M

    2013-05-01

    Transvertebral pedicle screws have successfully been used in the treatment of high-grade L5-S1 spondylolisthesis. An advantage of transvertebral pedicle screws is the purchase of multiple cortical layers across 2 vertebrae, thereby increasing the stability of the construct. At the lumbosacral junction, transvertebral pedicle screws have been shown to be biomechanically superior to pedicle screws placed in the standard fashion. The use of transvertebral pedicle screws at spinal levels other than L5-S1 has not been reported in the literature. The authors describe their technique of transvertebral pedicle screw placement in the thoracic spine using 3D image guidance. Twelve patients undergoing cervicothoracic or thoracolumbar fusion had 41 thoracic transvertebral pedicle screws placed across 26 spinal levels using this technique. Indications for placement of thoracic transvertebral pedicle screws in earlier cases included osteoporosis and pedicle screw salvage. However, in subsequent cases screws were placed in patients undergoing multilevel thoracolumbar fusion without osteoporosis, particularly near the top of the construct. Image guidance in this study was accomplished using the Medtronic StealthStation S7 image guidance system used in conjunction with the O-arm. All patients were slated to undergo postoperative CT scanning at approximately 4-6 months for fusion assessment, which also allowed for grading of the transvertebral pedicle screws. No thoracic transvertebral pedicle screw placed in this study had to be replaced or repositioned after intraoperative review of the cone beam CT scans. Review of the postoperative CT scans revealed all transvertebral screws to be across the superior disc space with the tips in the superior vertebral body. Six pedicle screws were placed using the in-out-in technique in patients with narrow pedicles, leaving 35 screws that underwent breach analysis. No pedicle breach was noted in 34 of 35 screws. A Grade 1 (image-guided placement

  8. Facet Joint Violation During Percutaneous Pedicle Screw Placement: A Comparison of Two Techniques.

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    Tannous, Oliver; Jazini, Ehsan; Weir, Tristan B; Banagan, Kelley E; Koh, Eugene Y; Greg Anderson, D; Gelb, Daniel E; Ludwig, Steven C

    2017-08-01

    A comparative study of facet joint violation (FJV) using two percutaneous surgical techniques. To compare the rate of iatrogenic FJV and medial pedicle wall breach between two methods of percutaneous pedicle screw instrumentation in the thoracic and lumbar spine. Variable iatrogenic damage to the facet joints has been reported to occur with percutaneous pedicle screw techniques, compared with the open approach, which has been associated with adjacent segment disease. Technical variations of percutaneous pedicle screw placement may pose different risks to the facet joint. Attending spine surgeons percutaneously placed pedicle screws in seven human cadaveric spines from T2 to L5. At each level, screws were instrumented on one side using the 9 or 3 o'clock reference point of the pedicle on the posteroanterior view with a lateral-to-medial trajectory (LMT) and on the contralateral side using the center of the pedicle with an owl's eye trajectory (OET). Postoperative screw placement was assessed with computed tomography and then open cadaveric dissection. Outcome measures included FJV and medial pedicle wall breach. Overall, 17 of 105 screws placed with an LMT versus 49 of 105 screws placed with an OET violated or abutted the facet joint (P L1), and lumbar (L2-L5) levels (P = 0.003, 0.035, and 0.018, respectively). Medial pedicle wall breach occurred with 11 LMT screws and seven OET screws (P = 0.077), and no breach was considered critical. A significantly higher FJV rate was observed using the OET versus the LMT in the thoracic, thoracolumbar, and lumbar spine. No statistically significant differences in medial pedicle wall breach occurred between the techniques. Thus, the LMT of minimally invasive pedicle screw fixation may reduce iatrogenic damage to the facet joints. 3.

  9. A phenotypic structure and neural correlates of compulsive behaviors in adolescents.

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    Chantale Montigny

    Full Text Available A compulsivity spectrum has been hypothesized to exist across Obsessive-Compulsive disorder (OCD, Eating Disorders (ED, substance abuse (SA and binge-drinking (BD. The objective was to examine the validity of this compulsivity spectrum, and differentiate it from an externalizing behaviors dimension, but also to look at hypothesized personality and neural correlates.A community-sample of adolescents (N=1938; mean age 14.5 years, and their parents were recruited via high-schools in 8 European study sites. Data on adolescents' psychiatric symptoms, DSM diagnoses (DAWBA and substance use behaviors (AUDIT and ESPAD were collected through adolescent- and parent-reported questionnaires and interviews. The phenotypic structure of compulsive behaviors was then tested using structural equation modeling. The model was validated using personality variables (NEO-FFI and TCI, and Voxel-Based Morphometry (VBM analysis.Compulsivity symptoms best fit a higher-order two factor model, with ED and OCD loading onto a compulsivity factor, and BD and SA loading onto an externalizing factor, composed also of ADHD and conduct disorder symptoms. The compulsivity construct correlated with neuroticism (r=0.638; p ≤ 0.001, conscientiousness (r=0.171; p ≤ 0.001, and brain gray matter volume in left and right orbitofrontal cortex, right ventral striatum and right dorsolateral prefrontal cortex. The externalizing factor correlated with extraversion (r=0.201; p ≤ 0.001, novelty-seeking (r=0.451; p ≤ 0.001, and negatively with gray matter volume in the left inferior and middle frontal gyri.Results suggest that a compulsivity spectrum exists in an adolescent, preclinical sample and accounts for variance in both OCD and ED, but not substance-related behaviors, and can be differentiated from an externalizing spectrum.

  10. Modular Adaptive System Based on a Multi-Stage Neural Structure for Recognition of 2D Objects of Discontinuous Production

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    I. Topalova

    2005-03-01

    Full Text Available This is a presentation of a new system for invariant recognition of 2D objects with overlapping classes, that can not be effectively recognized with the traditional methods. The translation, scale and partial rotation invariant contour object description is transformed in a DCT spectrum space. The obtained frequency spectrums are decomposed into frequency bands in order to feed different BPG neural nets (NNs. The NNs are structured in three stages - filtering and full rotation invariance; partial recognition; general classification. The designed multi-stage BPG Neural Structure shows very good accuracy and flexibility when tested with 2D objects used in the discontinuous production. The reached speed and the opportunuty for an easy restructuring and reprogramming of the system makes it suitable for application in different applied systems for real time work.

  11. Self-awareness in neurodegenerative disease relies on neural structures mediating reward-driven attention

    Science.gov (United States)

    Shany-Ur, Tal; Lin, Nancy; Rosen, Howard J.; Sollberger, Marc; Miller, Bruce L.

    2014-01-01

    Accurate self-awareness is essential for adapting one’s tasks and goals to one’s actual abilities. Patients with neurodegenerative diseases, particularly those with right frontal involvement, often present with poor self-awareness of their functional limitations that may exacerbate their already jeopardized decision-making and behaviour. We studied the structural neuroanatomical basis for impaired self-awareness among patients with neurodegenerative disease and healthy older adults. One hundred and twenty-four participants (78 patients with neurodegenerative diseases including Alzheimer’s disease, behavioural variant frontotemporal dementia, right-temporal frontotemporal dementia, semantic variant and non-fluent variant primary progressive aphasia, and 46 healthy controls) described themselves on the Patient Competency Rating Scale, rating observable functioning across four domains (daily living activities, cognitive, emotional control, interpersonal). All participants underwent structural magnetic resonance imaging. Informants also described subjects’ functioning on the same scale. Self-awareness was measured by comparing self and informant ratings. Group differences in discrepancy scores were analysed using general linear models, controlling for age, sex and disease severity. Compared with controls, patients with behavioural variant frontotemporal dementia overestimated their functioning in all domains, patients with Alzheimer’s disease overestimated cognitive and emotional functioning, patients with right-temporal frontotemporal dementia overestimated interpersonal functioning, and patients with non-fluent aphasia overestimated emotional and interpersonal functioning. Patients with semantic variant aphasia did not overestimate functioning on any domain. To examine the neuroanatomic correlates of impaired self-awareness, discrepancy scores were correlated with brain volume using voxel-based morphometry. To identify the unique neural correlates of

  12. Analysis of the internal representations developed by neural networks for structures applied to quantitative structure--activity relationship studies of benzodiazepines.

    Science.gov (United States)

    Micheli, A; Sperduti, A; Starita, A; Bianucci, A M

    2001-01-01

    An application of recursive cascade correlation (CC) neural networks to quantitative structure-activity relationship (QSAR) studies is presented, with emphasis on the study of the internal representations developed by the neural networks. Recursive CC is a neural network model recently proposed for the processing of structured data. It allows the direct handling of chemical compounds as labeled ordered directed graphs, and constitutes a novel approach to QSAR. The adopted representation of molecular structure captures, in a quite general and flexible way, significant topological aspects and chemical functionalities for each specific class of molecules showing a particular chemical reactivity or biological activity. A class of 1,4-benzodiazepin-2-ones is analyzed by the proposed approach. It compares favorably versus the traditional QSAR treatment based on equations. To show the ability of the model in capturing most of the structural features that account for the biological activity, the internal representations developed by the networks are analyzed by principal component analysis. This analysis shows that the networks are able to discover relevant structural features just on the basis of the association between the molecular morphology and the target property (affinity).

  13. The Effect of an Enrichment Reading Program on the Cognitive Processes and Neural Structures of Children Having Reading Difficulties

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    Hayriye Gül KURUYER

    2017-06-01

    Full Text Available The main purpose of the current study is to explain the effect of an enrichment reading program on the cognitive processes and neural structures of children experiencing reading difficulties. The current study was carried out in line with a single-subject research method and the between-subjects multiple probe design belonging to this method. This research focuses on a group of eight students with reading difficulties. Within the context of the study, memory capacities, attention spans, reading-related activation and white matter pathways of the students were determined before and after the application of the enrichment reading program. This determination process was carried out in two stages. Neuro-imaging was performed in the first stage and in the second stage the students’ cognitive processes and neural structures were investigated in terms of focusing attention and memory capacities by using the following tools: Stroop Test TBAG Form, Auditory Verbal Digit Span Test-Form B, Cancellation Test and Number Order Learning Test. The results obtained show that the enrichment reading program resulted in an improvement in the reading profiles of the students having reading difficulties in terms of their cognitive processes and neural structures.

  14. Preliminary experimental results of radiofrequency-cement-augmented and cannulated pedicle screws

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    Goost H

    2011-01-01

    Full Text Available The risk of cut-out of a pedicle screw is high in the presence of osteoporotic bone. In cadaver studies it was found that cement augmentation of pedicle screws markedly increases pullout forces. However, the use of conventional low viscosity vertebroplasty or kyphoplasty cement is associated with the risk of cement extravasation. The risk might be reduced by using high viscosity, radiofrequency-activated bone cement. After performing DEXA scans, six fresh-frozen vertebral bodies of different bone densities were obtained from cadavers. Two pedicle screws (WSI Expertise-Inject, Peter Brehm, Germany were placed in the pedicles. About 3 ml of radiofrequency-activated, ultra-high viscosity cement (ER2 Bone Cement, DFine Europe GmbH, Germany was injected through the right pedicle. The left pedicle screw was left uncemented and served as control. Axial pullout tests were performed using a material testing device (Zwick/Roell Zmartpro, Ulm, Germany. The tests revealed that cementaugmented pedicle screws were able to withstand markedly higher pullout forces. Extravasation of cement did not occur. The value of the study is limited by the fact that only six samples were investigated. Further cadaver studies and clinical evaluation will be needed in the future. However, this pilot study showed that combining cannulated pedicle screws with ultra-high viscosity bone cement is a successful approach. Revision due to cut-out and complications secondary to cement extravasation can be reduced by this method.

  15. Robot assisted navigated drilling for percutaneous pedicle screw placement: A preliminary animal study

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    Hongwei Wang

    2015-01-01

    Conclusions: The preliminary study supports the view that computer assisted pedicle screw fixation using spinal robot is feasible and the robot can decrease the intraoperative fluoroscopy time during the minimally invasive pedicle screw fixation surgery. As spine robotic surgery is still in its infancy, further research in this field is worthwhile especially the accuracy of spine robot system should be improved.

  16. Role of Dynesys as Pedicle-Based Nonfusion Stabilization for Degenerative Disc Disorders

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    Neel Anand

    2012-01-01

    Full Text Available Posterior nonfusion pedicle-screw-based stabilization remains a controversial area of spine surgery. To date, the Dynesys system remains the most widely implanted posterior nonfusion pedicle screw system. We review the history of Dynesys and discuss clinical outcome studies and biomechanical evaluations regarding the Dynesys system. Indications for surgery and controversies are discussed. Recommendations are made regarding technical implantation.

  17. Complications of pedicle screws in lumbar and lumbosacral fusions in 105 consecutive primary operations

    NARCIS (Netherlands)

    Jutte, PC

    2002-01-01

    Pedicle screw fixation is technically demanding and associated with high complication rates. The aim of this study was to identify and quantify the pedicle screw-related complications in 105 consecutive operations. We retrospectively analysed 105 consecutive primary operations. We found

  18. The Burden of Binge and Heavy Drinking on the Brain: Effects on Adolescent and Young Adult Neural Structure and Function

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    Anita Cservenka

    2017-06-01

    Full Text Available Introduction: Adolescence and young adulthood are periods of continued biological and psychosocial maturation. Thus, there may be deleterious effects of consuming large quantities of alcohol on neural development and associated cognition during this time. The purpose of this mini review is to highlight neuroimaging research that has specifically examined the effects of binge and heavy drinking on adolescent and young adult brain structure and function.Methods: We review cross-sectional and longitudinal studies of young binge and heavy drinkers that have examined brain structure (e.g., gray and white matter volume, cortical thickness, white matter microstructure and investigated brain response using functional magnetic resonance imaging (fMRI.Results: Binge and heavy-drinking adolescents and young adults have systematically thinner and lower volume in prefrontal cortex and cerebellar regions, and attenuated white matter development. They also show elevated brain activity in fronto-parietal regions during working memory, verbal learning, and inhibitory control tasks. In response to alcohol cues, relative to controls or light-drinking individuals, binge and heavy drinkers show increased neural response mainly in mesocorticolimbic regions, including the striatum, anterior cingulate cortex (ACC, hippocampus, and amygdala. Mixed findings are present in risky decision-making tasks, which could be due to large variation in task design and analysis.Conclusions: These findings suggest altered neural structure and activity in binge and heavy-drinking youth may be related to the neurotoxic effects of consuming alcohol in large quantities during a highly plastic neurodevelopmental period, which could result in neural reorganization, and increased risk for developing an alcohol use disorder (AUD.

  19. EFFECT OF PILOT HOLE TAPPING ON PULLOUT STRENGTH AND INSERTION TORQUE OF DUAL CORE PEDICLE SCREWS.

    Science.gov (United States)

    Rosa, Rodrigo César; Silva, Patrícia; Falcai, Maurício José; Shimano, Antônio Carlos; Defino, Helton Luiz Aparecido

    2010-01-01

    To evaluate the influence of pilot hole tapping on pullout resistance and insertion torque of pedicle screws with a conical core. Mechanical tests using a universal testing machine were performed on pedicle screws with a conical core that were inserted into pedicles in the fifth lumbar vertebra of calves. The insertion torque was measured using a torque meter with a capacity of 10 Nm, which was considered to be the highest torque value. The pilot holes were prepared using a probe of external diameter 3.8 mm and tapping of the same dimensions and thread characteristics as the screw. Decreased insertion torque and pullout resistance were observed in the group with prior tapping of the pilot hole. Pilot hole tapping reduced the insertion torque and pullout resistance of pedicle screws with a conical core that had been inserted into the pedicle of the fifth lumbar vertebra of calves.

  20. Correlation of bone equivalent mineral density to pull-out resistance of triangulated pedicle screw construct.

    Science.gov (United States)

    Hadjipavlou, A G; Nicodemus, C L; al-Hamdan, F A; Simmons, J W; Pope, M H

    1997-02-01

    Thirty single-pedicle and triangulated pedicle screws were subjected to pull-out tests until complete dislodgment was achieved. Peak load, displacement curves, angle of triangulation, and equivalent mineral density were recorded. Dual pedicle screw triangulation produced a 154.4% increase in peak pull-out strength compared with that of the single pedicle screw. Salvage triangulation (replacing failed screws with a triangulation construct) produced a 127.4% increase in peak strength over that of the single screw. Positive correlation was found between individual screw peak strength, bone mineral density, and displacement at peak load. Primary and salvage triangulation produced higher resistance to pull-out than a single pedicle screw, which reflects the potential, beneficial effect of using this technique. Triangulation, therefore, can be used as primary (prophylactic) technique to enhance pedicular screw pull-out during forceful vertebral manipulation.

  1. Prediction of Deformity Correction by Pedicle Screw Instrumentation in Thoracolumbar Scoliosis Surgery

    Science.gov (United States)

    Kiriyama, Yoshimori; Yamazaki, Nobutoshi; Nagura, Takeo; Matsumoto, Morio; Chiba, Kazuhiro; Toyama, Yoshiaki

    In segmental pedicle screw instrumentation, the relationship between the combinations of pedicle screw placements and the degree of deformity correction was investigated with a three-dimensional rigid body and spring model. The virtual thoracolumbar scoliosis (Cobb’s angle of 47 deg.) was corrected using six different combinations of pedicle-screw placements. As a result, better correction in the axial rotation was obtained with the pedicle screws placed at or close to the apical vertebra than with the screws placed close to the end vertebrae, while the correction in the frontal plane was better with the screws close to the end vertebrae than with those close to the apical vertebra. Additionally, two screws placed in the convex side above and below the apical vertebra provided better correction than two screws placed in the concave side. Effective deformity corrections of scoliosis were obtained with the proper combinations of pedicle screw placements.

  2. A Feedback Model of Attention Explains the Diverse Effects of Attention on Neural Firing Rates and Receptive Field Structure: e1004770

    National Research Council Canada - National Science Library

    Thomas Miconi; Rufin VanRullen

    2016-01-01

      Visual attention has many effects on neural responses, producing complex changes in firing rates, as well as modifying the structure and size of receptive fields, both in topological and feature space...

  3. Periosteal Pedicle Flap Harvested during Vestibular Extension for Root Coverage

    Directory of Open Access Journals (Sweden)

    Shubham Kumar

    2015-01-01

    Full Text Available Root exposure along with inadequate vestibular depth is a common clinical finding. Treatment option includes many techniques to treat such defects for obtaining predictable root coverage. Normally, the vestibular depth is increased first followed by a second surgery for root coverage. The present case report describes a single-stage technique for vestibular extension and root coverage in a single tooth by using the Periosteal Pedicle Flap (PPF. This technique involves no donor site morbidity and allows for reflection of sufficient amount of periosteal flap tissue with its own blood supply at the surgical site, thus increasing the chances of success of root coverage with simultaneous increase in vestibular depth.

  4. Effects of bursting dynamic features on the generation of multi-clustered structure of neural network with symmetric spike-timing-dependent plasticity learning rule.

    Science.gov (United States)

    Liu, Hui; Song, Yongduan; Xue, Fangzheng; Li, Xiumin

    2015-11-01

    In this paper, the generation of multi-clustered structure of self-organized neural network with different neuronal firing patterns, i.e., bursting or spiking, has been investigated. The initially all-to-all-connected spiking neural network or bursting neural network can be self-organized into clustered structure through the symmetric spike-timing-dependent plasticity learning for both bursting and spiking neurons. However, the time consumption of this clustering procedure of the burst-based self-organized neural network (BSON) is much shorter than the spike-based self-organized neural network (SSON). Our results show that the BSON network has more obvious small-world properties, i.e., higher clustering coefficient and smaller shortest path length than the SSON network. Also, the results of larger structure entropy and activity entropy of the BSON network demonstrate that this network has higher topological complexity and dynamical diversity, which benefits for enhancing information transmission of neural circuits. Hence, we conclude that the burst firing can significantly enhance the efficiency of clustering procedure and the emergent clustered structure renders the whole network more synchronous and therefore more sensitive to weak input. This result is further confirmed from its improved performance on stochastic resonance. Therefore, we believe that the multi-clustered neural network which self-organized from the bursting dynamics has high efficiency in information processing.

  5. Effects of bursting dynamic features on the generation of multi-clustered structure of neural network with symmetric spike-timing-dependent plasticity learning rule

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hui; Song, Yongduan; Xue, Fangzheng; Li, Xiumin, E-mail: xmli@cqu.edu.cn [Key Laboratory of Dependable Service Computing in Cyber Physical Society of Ministry of Education, Chongqing University, Chongqing 400044 (China); College of Automation, Chongqing University, Chongqing 400044 (China)

    2015-11-15

    In this paper, the generation of multi-clustered structure of self-organized neural network with different neuronal firing patterns, i.e., bursting or spiking, has been investigated. The initially all-to-all-connected spiking neural network or bursting neural network can be self-organized into clustered structure through the symmetric spike-timing-dependent plasticity learning for both bursting and spiking neurons. However, the time consumption of this clustering procedure of the burst-based self-organized neural network (BSON) is much shorter than the spike-based self-organized neural network (SSON). Our results show that the BSON network has more obvious small-world properties, i.e., higher clustering coefficient and smaller shortest path length than the SSON network. Also, the results of larger structure entropy and activity entropy of the BSON network demonstrate that this network has higher topological complexity and dynamical diversity, which benefits for enhancing information transmission of neural circuits. Hence, we conclude that the burst firing can significantly enhance the efficiency of clustering procedure and the emergent clustered structure renders the whole network more synchronous and therefore more sensitive to weak input. This result is further confirmed from its improved performance on stochastic resonance. Therefore, we believe that the multi-clustered neural network which self-organized from the bursting dynamics has high efficiency in information processing.

  6. An application of neural network for Structural Health Monitoring of an adaptive wing with an array of FBG sensors

    Energy Technology Data Exchange (ETDEWEB)

    Mieloszyk, Magdalena; Skarbek, Lukasz; Ostachowicz, Wieslaw [IFFM PASci, Fiszera14, 80-952 Gdansk (Poland); Krawczuk, Marek, E-mail: mmieloszyk@imp.gda.pl [IFFM PASci, Fiszera 14, 80-952 Gdansk and Technical University of Gdansk, Wlasna Strzecha 18a Street, 80-233, Gdansk (Poland)

    2011-07-19

    This paper presents an application of neural networks to determinate the level of activation of shape memory alloy actuators of an adaptive wing. In this concept the shape of the wing can be controlled and altered thanks to the wing design and the use of integrated shape memory alloy actuators. The wing is assumed as assembled from a number of wing sections that relative positions can be controlled independently by thermal activation of shape memory actuators. The investigated wing is employed with an array of Fibre Bragg Grating sensors. The Fibre Bragg Grating sensors with combination of a neural network have been used to Structural Health Monitoring of the wing condition. The FBG sensors are a great tool to control the condition of composite structures due to their immunity to electromagnetic fields as well as their small size and weight. They can be mounted onto the surface or embedded into the wing composite material without any significant influence on the wing strength. The paper concentrates on analysis of the determination of the twisting moment produced by an activated shape memory alloy actuator. This has been analysed both numerically using the finite element method by a commercial code ABAQUS (registered) and experimentally using Fibre Bragg Grating sensor measurements. The results of the analysis have been then used by a neural network to determine twisting moments produced by each shape memory alloy actuator.

  7. Neural-network-based depth-resolved multiscale structural optimization using density functional theory and electron diffraction data

    Science.gov (United States)

    Pennington, Robert S.; Coll, Catalina; Estradé, Sònia; Peiró, Francesca; Koch, Christoph T.

    2018-01-01

    Iterative neural-network-based three-dimensional structural optimization of atomic positions over tens of nanometers is performed using transmission electron microscope (TEM) diffraction data simulated from density functional theory (DFT) all-electron densities, thus retrieving parameter variations along the beam direction. We first use experimental data to show that the GPAW DFT code's all-electron densities are considerably more accurate for electron diffraction calculations compared to conventional isolated-atom scattering factors, and they also compare well to Wien2K DFT simulations. This DFT-TEM combination is then integrated into an iterative neural-network-optimization-based algorithm (PRIMES, parameter retrieval and inversion from multiple electron scattering) to retrieve nanometer-scale ferroelectric polarization domains and strain in theoretical bulklike specimens from TEM data. DFT and isolated-atom methods produce substantially different diffraction patterns and retrieved polarization domain parameters, and DFT is sufficient to retrieve strain properties from a silicon specimen simulated using experimentally derived structure factors. Thus, we show that the improved accuracy, fast computation, and intuitive integration make the GPAW DFT code well suited for three-dimensional materials characterization and demonstrate this using an iterative neural-network algorithm that is verifiable on the mesoscale and, with DFT integration, self-consistent on the nanoscale.

  8. Comparison of Neural Network Error Measures for Simulation of Slender Marine Structures

    DEFF Research Database (Denmark)

    Christiansen, Niels H.; Voie, Per Erlend Torbergsen; Winther, Ole

    2014-01-01

    platform is designed and tested. The purpose of setting up the network is to reduce calculation time in a fatigue life analysis. Therefore, the networks trained on different error functions are compared with respect to accuracy of rain flow counts of stress cycles over a number of time series simulations......Training of an artificial neural network (ANN) adjusts the internal weights of the network in order to minimize a predefined error measure. This error measure is given by an error function. Several different error functions are suggested in the literature. However, the far most common measure...... for regression is the mean square error. This paper looks into the possibility of improving the performance of neural networks by selecting or defining error functions that are tailor-made for a specific objective. A neural network trained to simulate tension forces in an anchor chain on a floating offshore...

  9. The artist emerges: visual art learning alters neural structure and function.

    Science.gov (United States)

    Schlegel, Alexander; Alexander, Prescott; Fogelson, Sergey V; Li, Xueting; Lu, Zhengang; Kohler, Peter J; Riley, Enrico; Tse, Peter U; Meng, Ming

    2015-01-15

    How does the brain mediate visual artistic creativity? Here we studied behavioral and neural changes in drawing and painting students compared to students who did not study art. We investigated three aspects of cognition vital to many visual artists: creative cognition, perception, and perception-to-action. We found that the art students became more creative via the reorganization of prefrontal white matter but did not find any significant changes in perceptual ability or related neural activity in the art students relative to the control group. Moreover, the art students improved in their ability to sketch human figures from observation, and multivariate patterns of cortical and cerebellar activity evoked by this drawing task became increasingly separable between art and non-art students. Our findings suggest that the emergence of visual artistic skills is supported by plasticity in neural pathways that enable creative cognition and mediate perceptuomotor integration. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Sequence and structural features of carbohydrate binding in proteins and assessment of predictability using a neural network

    Directory of Open Access Journals (Sweden)

    Ahmad Shandar

    2007-01-01

    Full Text Available Abstract Background Protein-Carbohydrate interactions are crucial in many biological processes with implications to drug targeting and gene expression. Nature of protein-carbohydrate interactions may be studied at individual residue level by analyzing local sequence and structure environments in binding regions in comparison to non-binding regions, which provide an inherent control for such analyses. With an ultimate aim of predicting binding sites from sequence and structure, overall statistics of binding regions needs to be compiled. Sequence-based predictions of binding sites have been successfully applied to DNA-binding proteins in our earlier works. We aim to apply similar analysis to carbohydrate binding proteins. However, due to a relatively much smaller region of proteins taking part in such interactions, the methodology and results are significantly different. A comparison of protein-carbohydrate complexes has also been made with other protein-ligand complexes. Results We have compiled statistics of amino acid compositions in binding versus non-binding regions- general as well as in each different secondary structure conformation. Binding propensities of each of the 20 residue types and their structure features such as solvent accessibility, packing density and secondary structure have been calculated to assess their predisposition to carbohydrate interactions. Finally, evolutionary profiles of amino acid sequences have been used to predict binding sites using a neural network. Another set of neural networks was trained using information from single sequences and the prediction performance from the evolutionary profiles and single sequences were compared. Best of the neural network based prediction could achieve an 87% sensitivity of prediction at 23% specificity for all carbohydrate-binding sites, using evolutionary information. Single sequences gave 68% sensitivity and 55% specificity for the same data set. Sensitivity and specificity

  11. "Free-hand" technique for thoracolumbar pedicle screw instrumentation: critical appraisal of current "state-of-art".

    Science.gov (United States)

    Mattei, Tobias A; Meneses, Murilo S; Milano, Jeronimo B; Ramina, Ricardo

    2009-01-01

    Pedicle screws are widely used for instrumentation of the thoracolumbar spine. The anatomic studies performed in the last two decades, detailing the complex morphometry and three-dimensional anatomy of the thoracolumbar pedicles, have enabled the emergence of the so-called "free-hand" technique of pedicle screw placement based exclusively on anatomical parameters. However, in the thoracic spine, the benefits of pedicle screws have been tempered by its potential risks, such as, spinal canal violation, pedicle fracture, nerve root compression, and vascular lesions. Furthermore, the narrow and inconsistent shape of the thoracic pedicles, especially in spinal deformity, makes their placement technically challenging. In this article, the authors make a critical appraisal of current "state-of-art" of "free-hand" technique of pedicle instrumentation, analyzing its anatomical basis, surgical technique, present indications and limitations as well as the role of adjuvant image-guided and neurophysiological monitoring methods.

  12. Power prediction in mobile communication systems using an optimal neural-network structure.

    Science.gov (United States)

    Gao, X M; Gao, X Z; Tanskanen, J A; Ovaska, S J

    1997-01-01

    Presents a novel neural-network-based predictor for received power level prediction in direct sequence code division multiple access (DS/CDMA) systems. The predictor consists of an adaptive linear element (Adaline) followed by a multilayer perceptron (MLP). An important but difficult problem in designing such a cascade predictor is to determine the complexity of the networks. We solve this problem by using the predictive minimum description length (PMDL) principle to select the optimal numbers of input and hidden nodes. This approach results in a predictor with both good noise attenuation and excellent generalization capability. The optimized neural networks are used for predictive filtering of very noisy Rayleigh fading signals with 1.8 GHz carrier frequency. Our results show that the optimal neural predictor can provide smoothed in-phase and quadrature signals with signal-to-noise ratio (SNR) gains of about 12 and 7 dB at the urban mobile speeds of 5 and 50 km/h, respectively. The corresponding power signal SNR gains are about 11 and 5 dB. Therefore, the neural predictor is well suitable for power control applications where ldquodelaylessrdquo noise attenuation and efficient reduction of fast fading are required.

  13. Travelling waves in models of neural tissue: from localised structures to periodic waves

    NARCIS (Netherlands)

    Meijer, Hil Gaétan Ellart; Coombes, Stephen

    2014-01-01

    We consider travelling waves (fronts, pulses and periodics) in spatially extended one dimensional neural field models. We demonstrate for an excitatory field with linear adaptation that, in addition to an expected stable pulse solution, a stable anti-pulse can exist. Varying the adaptation strength

  14. Neural signature of developmental coordination disorder in the structural connectome independent of comorbid autism.

    Science.gov (United States)

    Caeyenberghs, Karen; Taymans, Tom; Wilson, Peter H; Vanderstraeten, Guy; Hosseini, Hadi; van Waelvelde, Hilde

    2016-07-01

    Children with autism spectrum disorders (ASD) often exhibit motor clumsiness (Developmental Coordination Disorder, DCD), i.e. they struggle with everyday tasks that require motor coordination like dressing, self-care, and participating in sport and leisure activities. Previous studies in these neurodevelopmental disorders have demonstrated functional abnormalities and alterations of white matter microstructural integrity in specific brain regions. These findings suggest that the global organization of brain networks is affected in DCD and ASD and support the hypothesis of a 'dys-connectivity syndrome' from a network perspective. No studies have compared the structural covariance networks between ASD and DCD in order to look for the signature of DCD independent of comorbid autism. Here, we aimed to address the question of whether abnormal connectivity in DCD overlaps that seen in autism or comorbid DCD-autism. Using graph theoretical analysis, we investigated differences in global and regional topological properties of structural brain networks in 53 children: 8 ASD children with DCD (DCD+ASD), 15 ASD children without DCD (ASD), 11 with DCD only, and 19 typically developing (TD) children. We constructed separate structural correlation networks based on cortical thickness derived from Freesurfer. The children were assessed on the Movement-ABC and the Beery Test of Visual Motor Integration. Behavioral results demonstrated that the DCD group and DCD+ASD group scored on average poorer than the TD and ASD groups on various motor measures. Furthermore, although the brain networks of all groups exhibited small-world properties, the topological architecture of the networks was significantly altered in children with ASD compared with DCD and TD. ASD children showed increased normalized path length and higher values of clustering coefficient. Also, paralimbic regions exhibited nodal clustering coefficient alterations in singular disorders. These changes were disorder

  15. Superior segment facet joint violation and cortical violation after minimally invasive pedicle screw placement.

    Science.gov (United States)

    Knox, Jeffrey B; Dai, Joseph M; Orchowski, Joseph R

    2011-03-01

    Minimally invasive approaches to the lumbar spine allow for pedicle screw placement through a muscle-splitting paraspinal approach. These techniques are highly dependent on fluoroscopy and do not allow for direct visualization of anatomic landmarks. The effect of this on the accuracy of pedicle screw placement is not well described. The purpose of this study was to evaluate the rate of violation of the superior segment facet joint and rates of cortical violation after minimally invasive pedicle screw placement. To evaluate the rate of cortical violation and involvement of the superior segment facet after minimally invasive pedicle screw placement. Retrospective chart review. Patients who underwent minimally invasive pedicle screw placement by a single surgeon between January 2004 and July 2009. Violation of the superior segment facet joint or cortical violation identified on computed tomography (CT). This study consisted of a consecutive series of adult patients undergoing minimally invasive pedicle screw placement by a single surgeon for degenerative lumbar spinal conditions. Routine postoperative CT was obtained and evaluated for involvement of the superior segment facet joint and for cortical violation. Sixty-one consecutive patients (282 pedicle screws) met the study criteria and were included in the study, including 42 single-level fusions and 19 two-level fusions. Seven cortical breaches were identified for a rate of 2.48%. Seven patients had involvement of the superior-level facet for an incidence of 11.48%. One patient required revision for a malpositioned pedicle screw. This study revealed a low rate of superior segment facet violation and cortical violation after minimally invasive pedicle screw placement. This rate of superior-level facet involvement is significantly lower than previously reported after open procedures. The rate of cortical violation is similar to previous reports in the literature with a low revision rate. Published by Elsevier Inc.

  16. Genetic neural networks for quantitative structure-activity relationships: improvements and application of benzodiazepine affinity for benzodiazepine/GABAA receptors.

    Science.gov (United States)

    So, S S; Karplus, M

    1996-12-20

    A novel tool, called a genetic neural network (GNN), has been developed for obtaining quantitative structure-activity relationships (QSAR) for high-dimensional data sets (J. Med. Chem. 1996, 39, 1521-1530). The GNN method uses a neural network to correlate activity with descriptors that are preselected by a genetic algorithm. To provide an extended test of the GNN method, the data on 57 benzodiazepines given by Maddalena and Johnston (MJ; J. Med. Chem. 1995, 38, 715-724) have been examined with an enhanced version of GNN, and the results are compared with the excellent QSAR of MJ. The problematic steepest descent training has been replaced by the scaled conjugate gradient algorithm. This leads to a substantial gain in performance in both robustness of prediction and speed of computation. The cross-validation GNN simulation and the subsequent run based on an unbiased and more efficient protocol led to the discovery of other 10-descriptor QSARs that are superior to the best model of MJ based on backward elimination selection and neural network training. Results from a series of GNNs with a different number of inputs showed that a neural network with fewer inputs can produce QSARs as good as or even better than those with higher dimensions. The top-ranking models from a GNN simulation using only six input descriptors are presented, and the chemical significance of the chosen descriptors is discussed. The statistical significance of these GNN QSARs is validated. The best QSARs are used to provide a graphical tool that aids the design of new drug analogues. By replacing functional groups at the 7- and 2'-positions with ones that have optimal substituent parameters, a number of new benzodiazepines with high potency are predicted.

  17. Robot assisted navigated drilling for percutaneous pedicle screw placement: A preliminary animal study.

    Science.gov (United States)

    Wang, Hongwei; Zhou, Yue; Liu, Jun; Han, Jianda; Xiang, Liangbi

    2015-01-01

    There is much more radiation exposure to the surgeons during minimally invasive pedicle screws placement. In order to ease the surgeon's hand-eye coordination and to reduce the iatrogenic radiation injury to the surgeons, a robot assisted percutaneous pedicle screw placement is useful. This study assesses the feasibility and clinical value of robot assisted navigated drilling for pedicle screw placement and the results thus achieved formed the basis for the development of a new robot for pedicle screw fixation surgery. Preoperative computed tomography (CT) of eight bovine lumbar spines (L1-L5) in axial plane were captured for each vertebra, the entry points and trajectories of the screws were preoperatively planned. On the basis of preoperative CT scans and intraoperative fluoroscopy, we aligned the robot drill to the desired entry point and trajectory, as dictated by the surgeon's preoperative plan. Eight bovine lumbar spines were inserted 80 K-wires using the spine robot system. The time for system registration and pedicle drilling, fluoroscopy times were measured and recorded. Postoperative CT scans were used to assess the position of the K-wires. Assisted by spine robot system, the average time for system registration was (343.4 ± 18.4) s, the average time for procedure of drilling one pedicle screw trajectory was (89.5 ± 6.1) s, times of fluoroscopy for drilling one pedicle screw were (2.9 ± 0.8) times. Overall, 12 (15.0%) of the 80 K-wires violated the pedicle wall. Four screws (5.0%) were medial to the pedicle and 8 (10.5%) were lateral. The number of K-wires wholly within the pedicle were 68 (85%). The preliminary study supports the view that computer assisted pedicle screw fixation using spinal robot is feasible and the robot can decrease the intraoperative fluoroscopy time during the minimally invasive pedicle screw fixation surgery. As spine robotic surgery is still in its infancy, further research in this field is worthwhile especially the accuracy

  18. Optics-Only Calibration of a Neural-Net Based Optical NDE Method for Structural Health Monitoring

    Science.gov (United States)

    Decker, Arthur J.

    2004-01-01

    A calibration process is presented that uses optical measurements alone to calibrate a neural-net based NDE method. The method itself detects small changes in the vibration mode shapes of structures. The optics-only calibration process confirms previous work that the sensitivity to vibration-amplitude changes can be as small as 10 nanometers. A more practical value in an NDE service laboratory is shown to be 50 nanometers. Both model-generated and experimental calibrations are demonstrated using two implementations of the calibration technique. The implementations are based on previously published demonstrations of the NDE method and an alternative calibration procedure that depends on comparing neural-net and point sensor measurements. The optics-only calibration method, unlike the alternative method, does not require modifications of the structure being tested or the creation of calibration objects. The calibration process can be used to test improvements in the NDE process and to develop a vibration-mode-independence of damagedetection sensitivity. The calibration effort was intended to support NASA s objective to promote safety in the operations of ground test facilities or aviation safety, in general, by allowing the detection of the gradual onset of structural changes and damage.

  19. Spinal pedicle screw planning using deformable atlas registration

    Science.gov (United States)

    Goerres, J.; Uneri, A.; De Silva, T.; Ketcha, M.; Reaungamornrat, S.; Jacobson, M.; Vogt, S.; Kleinszig, G.; Osgood, G.; Wolinsky, J.-P.; Siewerdsen, J. H.

    2017-04-01

    Spinal screw placement is a challenging task due to small bone corridors and high risk of neurological or vascular complications, benefiting from precision guidance/navigation and quality assurance (QA). Implicit to both guidance and QA is the definition of a surgical plan—i.e. the desired trajectories and device selection for target vertebrae—conventionally requiring time-consuming manual annotations by a skilled surgeon. We propose automation of such planning by deriving the pedicle trajectory and device selection from a patient’s preoperative CT or MRI. An atlas of vertebrae surfaces was created to provide the underlying basis for automatic planning—in this work, comprising 40 exemplary vertebrae at three levels of the spine (T7, T8, and L3). The atlas was enriched with ideal trajectory annotations for 60 pedicles in total. To define trajectories for a given patient, sparse deformation fields from the atlas surfaces to the input (CT or MR image) are applied on the annotated trajectories. Mean value coordinates are used to interpolate dense deformation fields. The pose of a straight trajectory is optimized by image-based registration to an accumulated volume of the deformed annotations. For evaluation, input deformation fields were created using coherent point drift (CPD) to perform a leave-one-out analysis over the atlas surfaces. CPD registration demonstrated surface error of 0.89  ±  0.10 mm (median  ±  interquartile range) for T7/T8 and 1.29  ±  0.15 mm for L3. At the pedicle center, registered trajectories deviated from the expert reference by 0.56  ±  0.63 mm (T7/T8) and 1.12  ±  0.67 mm (L3). The predicted maximum screw diameter differed by 0.45  ±  0.62 mm (T7/T8), and 1.26  ±  1.19 mm (L3). The automated planning method avoided screw collisions in all cases and demonstrated close agreement overall with expert reference plans, offering a potentially valuable tool in support

  20. Measurement of weld penetration depths in thin structures using transmission coefficients of laser-generated Lamb waves and neural network.

    Science.gov (United States)

    Yang, Lei; Ume, I Charles

    2017-07-01

    The Laser/EMAT ultrasonic (LEU) technique has shown the capability to measure weld penetration depths in thick structures based on ray-tracing of laser-generated bulk and surface waves. The ray-tracing method is not applicable to laser-generated Lamb waves when the LEU technique is used to measure weld penetration depths in thin structures. In this work, transmission coefficients of Lamb waves present in the LEU signals are investigated against varying weld penetration depths. An artificial neural network is developed to use transmission coefficients of sensitive Lamb waves and LEU signal energy to predict weld penetration depths accurately. The developed method is very attractive because it allows a quick inspection of weld penetration depths in thin structures. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Modeling Distillation Column Using ARX Model Structure and Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Reza Pirmoradi

    2012-04-01

    Full Text Available Distillation is a complex and highly nonlinear industrial process. In general it is not always possible to obtain accurate first principles models for high-purity distillation columns. On the other hand the development of first principles models is usually time consuming and expensive. To overcome these problems, empirical models such as neural networks can be used. One major drawback of empirical models is that the prediction is valid only inside the data domain that is sufficiently covered by measurement data. Modeling distillation columns by means of neural networks is reported in literature by using recursive networks. The recursive networks are proper for modeling purpose, but such models have the problems of high complexity and high computational cost. The objective of this paper is to propose a simple and reliable model for distillation column. The proposed model uses feed forward neural networks which results in a simple model with less parameters and faster training time. Simulation results demonstrate that predictions of the proposed model in all regions are close to outputs of the dynamic model and the error in negligible. This implies that the model is reliable in all regions.

  2. Quantitative Live Imaging of Human Embryonic Stem Cell Derived Neural Rosettes Reveals Structure-Function Dynamics Coupled to Cortical Development.

    Science.gov (United States)

    Ziv, Omer; Zaritsky, Assaf; Yaffe, Yakey; Mutukula, Naresh; Edri, Reuven; Elkabetz, Yechiel

    2015-10-01

    Neural stem cells (NSCs) are progenitor cells for brain development, where cellular spatial composition (cytoarchitecture) and dynamics are hypothesized to be linked to critical NSC capabilities. However, understanding cytoarchitectural dynamics of this process has been limited by the difficulty to quantitatively image brain development in vivo. Here, we study NSC dynamics within Neural Rosettes--highly organized multicellular structures derived from human pluripotent stem cells. Neural rosettes contain NSCs with strong epithelial polarity and are expected to perform apical-basal interkinetic nuclear migration (INM)--a hallmark of cortical radial glial cell development. We developed a quantitative live imaging framework to characterize INM dynamics within rosettes. We first show that the tendency of cells to follow the INM orientation--a phenomenon we referred to as radial organization, is associated with rosette size, presumably via mechanical constraints of the confining structure. Second, early forming rosettes, which are abundant with founder NSCs and correspond to the early proliferative developing cortex, show fast motions and enhanced radial organization. In contrast, later derived rosettes, which are characterized by reduced NSC capacity and elevated numbers of differentiated neurons, and thus correspond to neurogenesis mode in the developing cortex, exhibit slower motions and decreased radial organization. Third, later derived rosettes are characterized by temporal instability in INM measures, in agreement with progressive loss in rosette integrity at later developmental stages. Finally, molecular perturbations of INM by inhibition of actin or non-muscle myosin-II (NMII) reduced INM measures. Our framework enables quantification of cytoarchitecture NSC dynamics and may have implications in functional molecular studies, drug screening, and iPS cell-based platforms for disease modeling.

  3. A Feedback Model of Attention Explains the Diverse Effects of Attention on Neural Firing Rates and Receptive Field Structure.

    Science.gov (United States)

    Miconi, Thomas; VanRullen, Rufin

    2016-02-01

    Visual attention has many effects on neural responses, producing complex changes in firing rates, as well as modifying the structure and size of receptive fields, both in topological and feature space. Several existing models of attention suggest that these effects arise from selective modulation of neural inputs. However, anatomical and physiological observations suggest that attentional modulation targets higher levels of the visual system (such as V4 or MT) rather than input areas (such as V1). Here we propose a simple mechanism that explains how a top-down attentional modulation, falling on higher visual areas, can produce the observed effects of attention on neural responses. Our model requires only the existence of modulatory feedback connections between areas, and short-range lateral inhibition within each area. Feedback connections redistribute the top-down modulation to lower areas, which in turn alters the inputs of other higher-area cells, including those that did not receive the initial modulation. This produces firing rate modulations and receptive field shifts. Simultaneously, short-range lateral inhibition between neighboring cells produce competitive effects that are automatically scaled to receptive field size in any given area. Our model reproduces the observed attentional effects on response rates (response gain, input gain, biased competition automatically scaled to receptive field size) and receptive field structure (shifts and resizing of receptive fields both spatially and in complex feature space), without modifying model parameters. Our model also makes the novel prediction that attentional effects on response curves should shift from response gain to contrast gain as the spatial focus of attention drifts away from the studied cell.

  4. Quantitative Live Imaging of Human Embryonic Stem Cell Derived Neural Rosettes Reveals Structure-Function Dynamics Coupled to Cortical Development.

    Directory of Open Access Journals (Sweden)

    Omer Ziv

    2015-10-01

    Full Text Available Neural stem cells (NSCs are progenitor cells for brain development, where cellular spatial composition (cytoarchitecture and dynamics are hypothesized to be linked to critical NSC capabilities. However, understanding cytoarchitectural dynamics of this process has been limited by the difficulty to quantitatively image brain development in vivo. Here, we study NSC dynamics within Neural Rosettes--highly organized multicellular structures derived from human pluripotent stem cells. Neural rosettes contain NSCs with strong epithelial polarity and are expected to perform apical-basal interkinetic nuclear migration (INM--a hallmark of cortical radial glial cell development. We developed a quantitative live imaging framework to characterize INM dynamics within rosettes. We first show that the tendency of cells to follow the INM orientation--a phenomenon we referred to as radial organization, is associated with rosette size, presumably via mechanical constraints of the confining structure. Second, early forming rosettes, which are abundant with founder NSCs and correspond to the early proliferative developing cortex, show fast motions and enhanced radial organization. In contrast, later derived rosettes, which are characterized by reduced NSC capacity and elevated numbers of differentiated neurons, and thus correspond to neurogenesis mode in the developing cortex, exhibit slower motions and decreased radial organization. Third, later derived rosettes are characterized by temporal instability in INM measures, in agreement with progressive loss in rosette integrity at later developmental stages. Finally, molecular perturbations of INM by inhibition of actin or non-muscle myosin-II (NMII reduced INM measures. Our framework enables quantification of cytoarchitecture NSC dynamics and may have implications in functional molecular studies, drug screening, and iPS cell-based platforms for disease modeling.

  5. Consciousness and neural plasticity

    DEFF Research Database (Denmark)

    In contemporary consciousness studies the phenomenon of neural plasticity has received little attention despite the fact that neural plasticity is of still increased interest in neuroscience. We will, however, argue that neural plasticity could be of great importance to consciousness studies....... If consciousness is related to neural processes it seems, at least prima facie, that the ability of the neural structures to change should be reflected in a theory of this relationship "Neural plasticity" refers to the fact that the brain can change due to its own activity. The brain is not static but rather...... a dynamic entity, which physical structure changes according to its use and environment. This change may take the form of growth of new neurons, the creation of new networks and structures, and change within network structures, that is, changes in synaptic strengths. Plasticity raises questions about...

  6. Breast reconstruction by pedicled transverse rectus abdominis myocutaneous flap

    Directory of Open Access Journals (Sweden)

    Kozarski Jefta

    2004-01-01

    Full Text Available Reconstruction of the amputated breast in female patients after surgical management of breast carcinoma is possible with the use of autologous tissue, synthetic implants, or by combining autologous tissue and synthetic materials. Autologous tissue provides soft and sufficiently elastic tissue which is usable for breast reconstruction and eventually obtains original characteristics of the surrounding tissue on the chest wall. The use of the TRAM flap for breast reconstruction was introduced in 1982 by Hartrampf Scheflan, and Black. The amount of the TRAM flap tissue allows breast reconstruction in the shape most adequate to the remaining breast. The possibilities of using the TRAM flap as pedicled myocutaneous flap or as free TRAM flap make this flap a superior choice for breast reconstruction in comparison with other flaps.

  7. Recovery of infraorbital nerve function after zygomaticomaxillary cheek pedicled flap.

    Science.gov (United States)

    Giannì, A B; Biglioli, F; Brevi, B; Brusati, R

    1995-10-01

    The zygomaticomaxillary cheek pedicled flap (ZMCF) involves the intentional section of the infraorbital nerve to reflect the flap laterally in order to give access to the rhinopharynx, clivus and upper cervical spine. The aim of this trial was to examine the recovery of sensation of the infraorbital nerve, both quantitatively (touch sensation, localisation test, two-point discrimination) and qualitatively (sharp/blunt test, temperature sensation, pain sensitivity, dental sensitivity) in 7 patients, at least 12 months after surgery. In each patient, four cutaneous areas (lower eyelid, nose ala, upper lip, cheek) and the upper vestibulum were tested. Results of each test in all the examined areas were evaluated and compared with the data obtained on the nonoperated side (control side). Results of neurosensory tests indicated good recovery of sensation with little difference in comparison with the control side, showing that the functional consequence of ZMCF should actually be considered only as a transitory event.

  8. Sagittal balance analysis after pedicle subtraction osteotomy in ankylosing spondylitis.

    Science.gov (United States)

    Debarge, Romain; Demey, Guillaume; Roussouly, Pierre

    2011-09-01

    This is a radiographic study of ankylosing spondylitis patients with severe fixed kyphotic deformity who underwent pedicle subtraction osteotomy. Our goal was to measure and validate new angle to assess global kyphosis and to evaluate the sagittal balance after surgery. This is the first report which describes new angle to assess global kyphosis (T1-S1). Pre and postoperative controls were compared according to the Pelvic Incidence. The sagittal parameters ankylosing spondylitis patients were compared with 154 asymptomatic patients. In addition to the pelvic parameters and the C7 tilt, we used the spino-sacral angle. Pelvic incidence in ankylosing spondylitis patients was higher than asymptomatic population (61° vs. 51°). For a same tilt of C7 for both groups, the low pelvic incidence group had a lower sacral slope and pelvic tilt and a higher global kyphosis (spino-sacral angle = 90°) than the high pelvic incidence group (spino-sacral angle = 98°). In the adult volunteers, the C7 tilt and spino-sacral angle measured, respectively, 95° and 135°. The preoperative C7 tilt measured 73° and increased to 83° (p = 0.0025). The preoperative spino-sacral angle measured 96° and increased to 113.3° (p = 0.003). A low pelvic incidence pelvis has a lower sacral slope than in high pelvic incidence and can support a bigger kyphosis. All the parameters were improved by the pedicle subtraction osteotomy, but the average spinosacral angle remained lower than the control group. When C7 tilt was useful to assess the improvement of the sagittal balance, SSA allowed a better evaluation of the correction of kyphosis itself.

  9. [Progress on atlanto-axial pedicle screw fixation through posterior approach].

    Science.gov (United States)

    Li, Guo-Qing; Ma, Wei-Hu; Liu, Guan-Yi

    2014-06-01

    The present of atlanto-axial pedicle screw fixation through posterior approach provide a new remedy for treating instability of pillow and cervical. A lot of researches have reported feasibility of atlanto-axial pedicle screw fixation, the results showed that it had advantages of easily exposure, less blood loss, shorter operative time, especially in treating as remedy fixation for atlanto-axial joint screw, atlas lateral mass screws and pedicle screw caused by injuries of tumor,inflammation and trauma. If not done properly, it can cause serious complications, such as iatrogenic fracture,injuries of vertebral artery and cervical spinal cord. Therefore,the safty and effectiveness of atlanto-axial pedicle screw fixation may be focus of research.

  10. The Pedicled LICAP Flap Combined with a Free Abdominal Flap In Autologous Breast Reconstructions

    Directory of Open Access Journals (Sweden)

    Thomas Sjøberg, MD

    2018-01-01

    Conclusion:. In selected patients with insufficient abdominal flap tissue, a combination of a free abdominal flap and a pedicled LICAP flap is a valuable option to increase breast size and cosmetic outcome. Additional symmetrizing surgery might still be necessary.

  11. A novel route for placing free flap pedicle from a palatal defect.

    Science.gov (United States)

    Ahuja, Rajeev B; Chatterjee, Pallab; Shrivastava, Prabhat

    2014-05-01

    One of the better options available to repair a large palatal defect is by employing a free flap. Almost all the times such free flaps are plumbed to facial vessels. The greatest challenge in such cases is the placement of the pedicle from palatal shelf to recipient vessels because there is no direct route available. As majority of large palatal fistulae are encountered in operated cleft palates there is a possibility of routing the pedicle through a cleft in the maxillary arch or via pyriform aperture. When such a possibility doesn't exist the pedicle is routed behind the maxillary arch. We describe a novel technique of pedicle placement through a maxillary antrostomy, in this case report, where a large palatal fistula in a 16 year old boy was repaired employing a free radial artery forearm flap. The direct route provided by maxillary antrostomy is considered the most expeditious of all possibilities mentioned above.

  12. A novel route for placing free flap pedicle from a palatal defect

    Directory of Open Access Journals (Sweden)

    Rajeev B Ahuja

    2014-01-01

    Full Text Available One of the better options available to repair a large palatal defect is by employing a free flap. Almost all the times such free flaps are plumbed to facial vessels. The greatest challenge in such cases is the placement of the pedicle from palatal shelf to recipient vessels because there is no direct route available. As majority of large palatal fistulae are encountered in operated cleft palates there is a possibility of routing the pedicle through a cleft in the maxillary arch or via pyriform aperture. When such a possibility doesn′t exist the pedicle is routed behind the maxillary arch. We describe a novel technique of pedicle placement through a maxillary antrostomy, in this case report, where a large palatal fistula in a 16 year old boy was repaired employing a free radial artery forearm flap. The direct route provided by maxillary antrostomy is considered the most expeditious of all possibilities mentioned above.

  13. [BIOMECHANICAL STRENGTH INFLUENCE OF LATERAL WALL VIOLATION ON SPINAL PEDICLE SCREW FIXATION].

    Science.gov (United States)

    Zhuang, Yan; Cao, Xiaojian

    2015-02-01

    To compare the fixation strength of optimum placed pedicle screw (OS) with redirectionally correctly placed pedicle screw (RS) following a violation of lateral pedicle. Thirty fresh lumbar vertebrae (L1-5) were obtained from 6 pigs weighing 95-105 kg, male or female. Each vertebra was instrumented with a monoaxial pedicle screw into each pedicle using two different techniques. On one side, a perfect screw path was created using direct visualization and fluoroscopy. A pedicle screw of 5 mm in diameter and 35 mm in length was placed with a digital torque driver (OS). On the other side, a lateral pedicle wall violation was created at the pedicle-vertebral body junction with a guide wire, a cannulated tap, and a pedicle probe. This path was then redirected into a correct position, developed, and instrumented with a 5-mm-diameter by 35-mm-long pedicle screw (RS). For each pedicle screw, the maximal torque, seating torque, screw loosening force, and post-loosening axial pullout were measured. Screw loosening and axial pullout were assessed using an MTS machine. Maximal insertion torque was (111.4 ± 8.2) N x cm and (78.9 ± 6.4) N x cm for OS and RS respectively, showing significant difference (Z = 3.038, P = 0.002). The seating torque was (86.3 ± 7.7) N x cm and (59.7 ± 5.3) N x cm for OS and RS respectively, showing significant difference (Z = 2.802, P = 0.005). The screw loosening force was (76.3 ± 6.2) N and (53.0 ± 5.8) N for OS and RS respectively, showing significant difference (Z = 2.861, P = 0.004). The post-loosening axial pullout force was (343.0 ± 12.6) N and (287.0?10.5) N for OS and RS respectively, showing significant difference (Z = 2.964, P = 0.003). Compared with OS, RS placement after a lateral wall violation shows significantly decreased maximal insertion torque, seating torque, screw loosening force, and post-loosening axial pullout. On this occasion, RS augmentation is a probable option for remediation.

  14. Fatigue Performance of Cortical Bone Trajectory Screw Compared With Standard Trajectory Pedicle Screw.

    Science.gov (United States)

    Akpolat, Yusuf Tahiri; İnceoğlu, Serkan; Kinne, Nolan; Hunt, Devon; Cheng, Wayne K

    2016-03-01

    Cadaveric biomechanical study. To determine fatigue behavior of cortical bone trajectory (CBT) pedicle screws. Cortical bone trajectory screws have been becoming popular in spine surgery; however, the long-term fatigue behavior of the new CBT screws remains understudied and limitations not well defined. Twelve vertebrae from six cadaveric lumbar spines were obtained. After bone mineral density (BMD) measurements, each vertebral body was instrumented with screws from each group, that is, CBT (4.5 × 25 mm) or standard pedicle screw (6.5 × 55 mm). A load (± 4 Nm sagittal bending) was applied under displacement control at 1 Hz. Each construct was loaded for 100 cycles or until 6° of loosening was observed. After fatigue testing, the screws were pulled out axially at 5 mm/min. The standard pedicle screw showed better resistance against 100 cycle loading compared with the CBT screws (P standard pedicle screw testing usually required more than 100 cycles of loading to achieve the critical loosening (3592 ± 4564 cycles), whereas the CBT screw never exceeded 100 cycles (84 ± 24 cycles) (P = 0.002). Increased BMD was significantly associated with a higher number of cycles and less loosening. The standard pedicle screw group had a higher postfatigue pullout load than the CBT screw group (P = 0.001, 776 ± 370 N and 302 ± 232 N, respectively). The standard pedicle screw had a better fatigue performance compared with the CBT screw in vertebra with compromised bone quality. The proper insertion of the CBT screw might be prevented by the laminar anatomy depending on the screw head design. The CBT screw damaged the bone along its shaft by rotating around a fulcrum, located at either the pars, pedicle isthmus, or the junction of the pedicle and superior endplate, contingent upon the strength of the bone.

  15. [Clinical efficiency of computer-assisted pedicle screw placement versus conventional method: a meta-analysis].

    Science.gov (United States)

    Xing, Dan; Ma, Xin-Long; Song, Dong-Hui; Ma, Jian-Xiong; Xu, Wei-Guo; Wang, Jie; Yang, Yang; Chen, Yang

    2012-10-01

    To compare the clinical efficacy of computer-assisted pedicle screw placement and conventional placement in the treatment of spinal disease. A systematic search of studies published between Jan. 1990 and Feb. 2012 was conducted using Medline, Embase, OVID, ScienceDirect and Cochrane Review databases. Randomized controlled trials (RCTs) and prospective controlled trials of comparing computer-assisted pedicle screw placement to conventional method performed at one center or multi-centers providing data on accuracy of placement and clinical effects were identified. Two study authors independently reviewed the 93 articles originally identified and selected 10 for analysis. Study title,demographic characteristics,number of pedicle screw,anatomical area and outcomes were extracted manually from all selected studies. RevMan 5.1 software was used for meta-analysis. Ten studies encompassing 2813 pedicle screws met the inclusion criteria. Overall,the result of meta-analysis indicated that there were significant differences between two groups in accuracy in placement of pedicle screw [OR = 2.58, 95% CI (1.18, 5.63)], insertion time [WMD = -2.15, 95% CI (-2.36, -1.94)]. However, there was only one study reported preparation time of pedicle screw of navigation group was longer than conventional group. No neurological complication in navigation group was reported. As a safety supplementary measure, computer navigation provide better accuracy in placement of pedicle screw and insertion time. The preparation time of pedicle screw may prolong due to the complexity of navigation system. Further reseach should include randomized controlled trials with well-planned methodology to limit bias.

  16. Alternative of pedicle buccal fat pad for reconstruction defect in cleft palate patient

    OpenAIRE

    Nur Hidayat; Muhammad Ruslin

    2016-01-01

    Various surgical techniques have been employed for closure of the defect in the oral cavity. The type and size of defects in the oral cavity determine the techniques to use. Pedicle Buccal Fat Pad (BFP) is one alternative tissue graft for defect reconstruction in oral cavity. The objective of this paper is to determine an alternative defect reconstruction in cleft palate using pedicle BFP. In conclusion, the use of BFP for the defect reconstruction in cleft palate patients shows satisfactory ...

  17. Neural plasticity expressed in central auditory structures with and without tinnitus

    Directory of Open Access Journals (Sweden)

    Larry E Roberts

    2012-05-01

    Full Text Available Sensory training therapies for tinnitus are based on the assumption that, notwithstanding neural changes related to tinnitus, auditory training can alter the response properties of neurons in auditory pathways. To address this question, we investigated whether brain changes induced by sensory training in tinnitus sufferers and measured by EEG are similar to those induced in age and hearing loss matched individuals without tinnitus trained on the same auditory task. Auditory training was given using a 5 kHz 40-Hz amplitude-modulated sound that was in the tinnitus frequency region of the tinnitus subjects and enabled extraction of the 40-Hz auditory steady-state response (ASSR and P2 transient response known to localize to primary and nonprimary auditory cortex, respectively. P2 amplitude increased with training equally in participants with tinnitus and in control subjects, suggesting normal remodeling of nonprimary auditory regions in tinnitus. However, training-induced changes in the ASSR differed between the tinnitus and control groups. In controls ASSR phase advanced toward the stimulus waveform by about ten degrees over training, in agreement with previous results obtained in young normal hearing individuals. However, ASSR phase did not change significantly with training in the tinnitus group, although some participants showed phase shifts resembling controls. On the other hand, ASSR amplitude increased with training in the tinnitus group, whereas in controls this response (which is difficult to remodel in young normal hearing subjects did not change with training. These results suggest that neural changes related to tinnitus altered how neural plasticity was expressed in the region of primary but not nonprimary auditory cortex. Auditory training did not reduce tinnitus loudness although a small effect on the tinnitus spectrum was detected.

  18. Weighted spiking neural P systems with structural plasticity working in sequential mode based on maximum spike number

    Science.gov (United States)

    Sun, Mingming; Qu, Jianhua

    2017-10-01

    Spiking neural P systems (SNP systems, in short) are a group of parallel and distributed computing devices inspired by the function and structure of spiking neurons. Recently, a new variant of SNP systems, called SNP systems with structural plasticity (SNPSP systems, in short) was proposed. In SNPSP systems, neuron can use plasticity ru les to create and delete synapses. In this work, we consider many restrictions sequentiality on SNPSP systems: (1) neuron with the maximum number of spikes is chosen to fire; (2) we use the weighted synapses. Specifically, we investigate the computational power of weighted SNPSP systems working in the sequential mode based on maximum spike number (WSNPSPM systems, in short) and we proved that SNPSP systems with these new restrictions are universal as generating devices.

  19. Crystal structure of the Ig1 domain of the neural cell adhesion molecule NCAM2 displays domain swapping.

    Science.gov (United States)

    Rasmussen, Kim K; Kulahin, Nikolaj; Kristensen, Ole; Poulsen, Jens-Christian N; Sigurskjold, Bent W; Kastrup, Jette S; Berezin, Vladimir; Bock, Elisabeth; Walmod, Peter S; Gajhede, Michael

    2008-10-24

    The crystal structure of the first immunoglobulin (Ig1) domain of neural cell adhesion molecule 2 (NCAM2/OCAM/RNCAM) is presented at a resolution of 2.7 A. NCAM2 is a member of the immunoglobulin superfamily of cell adhesion molecules (IgCAMs). In the structure, two Ig domains interact by domain swapping, as the two N-terminal beta-strands are interchanged. beta-Strand swapping at the terminal domain is the accepted mechanism of homophilic interactions amongst the cadherins, another class of CAMs, but it has not been observed within the IgCAM superfamily. Gel-filtration chromatography demonstrated the ability of NCAM2 Ig1 to form dimers in solution. Taken together, these observations suggest that beta-strand swapping could have a role in the molecular mechanism of homophilic binding for NCAM2.

  20. Classification of Forest Vertical Structure in South Korea from Aerial Orthophoto and Lidar Data Using an Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Soo-Kyung Kwon

    2017-10-01

    Full Text Available Every vegetation colony has its own vertical structure. Forest vertical structure is considered as an important indicator of a forest’s diversity and vitality. The vertical structure of a forest has typically been investigated by field survey, which is the traditional method of forest inventory. However, this method is very time- and cost-consuming due to poor accessibility. Remote sensing data such as satellite imagery, aerial photography, and lidar data can be a viable alternative to the traditional field-based forestry survey. In this study, we classified forest vertical structures from red-green-blue (RGB aerial orthophotos and lidar data using an artificial neural network (ANN, which is a powerful machine learning technique. The test site was Gongju province in South Korea, which contains single-, double-, and triple-layered forest structures. The performance of the proposed method was evaluated by comparing the results with field survey data. The overall accuracy achieved was about 70%. It means that the proposed approach can classify the forest vertical structures from the aerial orthophotos and lidar data.

  1. Clinical Application of a Pedicled Forearm Flap in the Reconstruction After Oral Cancer Resection.

    Science.gov (United States)

    Zhao, Xiaoqiang; Zhang, Youmei; Fu, Shuai; Zhang, Changbin; Li, Ming; Wu, Yong

    2017-05-01

    To investigate the clinical application of a pedicled forearm flap in the reconstruction of soft tissue defects after oral cancer resection. A retrospective analysis was performed on 31 patients with oral cancer in the Affiliated Stomatology Hospital of Kunming Medical University. The patients underwent repair of soft tissue defects, resulting from oral cancer resection, using a pedicled forearm flap. Patients were followed up for 3 months to 3 years to observe the survival rate of the pedicled forearm flap and the recovery of the patient's appearance and oral function. The pedicled forearm flap survived in 30 patients (96.77%), and 3 patients showed flap vascular crisis (9.67%; 2 patients were successfully rescued). The articulation, chewing, and swallowing function of the patients were improved after surgery. The pedicled forearm flap has advantages in terms of color and texture, its moderate thickness, long vascular pedicle, good blood supply, and strong infection resistance. It has a high survival rate and is an excellent skin-muscle flap suited to the repair of soft tissue defects after oral cancer resection.

  2. Unilateral Pedicle Stress Fracture in a Long-Term Hemodialysis Patient with Isthmic Spondylolisthesis

    Directory of Open Access Journals (Sweden)

    Keishi Maruo

    2015-01-01

    Full Text Available Most unilateral pedicle stress fractures occur on the contralateral side of patients with unilateral spondylolysis. However, there are few reports of unilateral pedicle stress fractures in patients with bilateral spondylolysis and spondylolisthesis. We report a unique case of unilateral pedicle stress fracture in a long-term hemodialysis patient with isthmic spondylolisthesis. A 65-year-old man who had undergone hemodialysis presented with lower back pain that had persisted for several years. The patient experienced severe right lower extremity pain with no history of trauma. Computed tomography revealed unilateral pedicle fracture with bilateral L5 spondylolysis and spondylolisthesis with progression of scoliosis. The patient underwent Gill laminectomy of L5 with pedicle screw fixation at L4-S1 and interbody fusion at L5-S1. The patient’s leg pain ceased immediately, and he began walking without leg pain. In our present patient, development of scoliosis caused by destructive spondyloarthropathy may have contributed to a unilateral pedicle fracture.

  3. Comparison of Unilateral versus Bilateral Pedicle Screw Fixation in Transforaminal Lumbar Interbody Fusion for Single Level Lumbar Degenerative Diseases and Review of Literature.

    Science.gov (United States)

    Işik, Hasan Serdar; Okutan, Özerk; Yildirim, Timur; Akpinar, Elif; Yilmaz, Ali

    2017-07-30

    There are some recognized treatment modalities in the literature for the treatment of lumbar degenerative diseases,which cause pain and avoidance of daily life activities for the patients.The most widely accepted algorithm in the literature is medical treatment,physical therapy and minimally invasive pain-relieving therapies,if necessary,followed by surgical interventions.The common procedure used in neurosurgery practice is the decompression of neural elements followed by fusion.It is reported in the literature that unilateral pedicle fixation and Transforaminal Lumbar Interbody Fusion(TLIF) procedure have many advantages compared to bilateral pedicle screw implementation(PSF).We examined the clinical and radiological follow-up and results of our patients undergoing fusion procedure by unilateral versus bilateral pedicle screw fixation along with TLIF. 54 patients were included in the study.33 patients were operated with bilateral PSF and TLIF and 21 had unilateral PSF and TLIF.The patients were evaluated preoperatively,on the postoperative 15th day,6th and 12th month, and at the time of last examination (38 months in average for all patients) using Visual Analogue Scale(VAS) and Oswestry Disability Index(ODI).Fusion rates were examined with direct X-ray films with flexion-extension dynamic views and 3D CT scan. Operation times are shorter and blood loss is less in the unilateral PSF group.Fusion rates are similar in both groups with no statistical significance.For both groups significant clinical improvement was observed in the preoperative and postoperative scores. Unilateral PSF along with TLIF procedure is an effective option in selected patients.We need prospective randomized studies with higher number of patients and longer follow-up periods for more reliable results.

  4. Segmentation of Bone Structure in X-ray Images using Convolutional Neural Network

    Directory of Open Access Journals (Sweden)

    CERNAZANU-GLAVAN, C.

    2013-02-01

    Full Text Available The segmentation process represents a first step necessary for any automatic method of extracting information from an image. In the case of X-ray images, through segmentation we can differentiate the bone tissue from the rest of the image. There are nowadays several segmentation techniques, but in general, they all require the human intervention in the segmentation process. Consequently, this article proposes a new segmentation method for the X-ray images using a Convolutional Neural Network (CNN. In present, the convolutional networks are the best techniques for image segmentation. This fact is demonstrated by their wide usage in all the fields, including the medical one. As the X-ray images have large dimensions, for reducing the training time, the method proposed by the present article selects only certain areas (maximum interest areas from the entire image. The neural network is used as pixel classifier thus causing the label of each pixel (bone or none-bone from a raw pixel values in a square area. We will also present the method through which the network final configuration was chosen and we will make a comparative analysis with other 3 CNN configurations. The network chosen by us obtained the best results for all the evaluation metrics used, i.e. warping error, rand error and pixel error.

  5. Structural Health Monitoring and Impact Detection Using Neural Networks for Damage Characterization

    Science.gov (United States)

    Ross, Richard W.

    2006-01-01

    Detection of damage due to foreign object impact is an important factor in the development of new aerospace vehicles. Acoustic waves generated on impact can be detected using a set of piezoelectric transducers, and the location of impact can be determined by triangulation based on the differences in the arrival time of the waves at each of the sensors. These sensors generate electrical signals in response to mechanical motion resulting from the impact as well as from natural vibrations. Due to electrical noise and mechanical vibration, accurately determining these time differentials can be challenging, and even small measurement inaccuracies can lead to significant errors in the computed damage location. Wavelet transforms are used to analyze the signals at multiple levels of detail, allowing the signals resulting from the impact to be isolated from ambient electromechanical noise. Data extracted from these transformed signals are input to an artificial neural network to aid in identifying the moment of impact from the transformed signals. By distinguishing which of the signal components are resultant from the impact and which are characteristic of noise and normal aerodynamic loads, the time differentials as well as the location of damage can be accurately assessed. The combination of wavelet transformations and neural network processing results in an efficient and accurate approach for passive in-flight detection of foreign object damage.

  6. Effects of multitasking-training on gray matter structure and resting state neural mechanisms.

    Science.gov (United States)

    Takeuchi, Hikaru; Taki, Yasuyuki; Nouchi, Rui; Hashizume, Hiroshi; Sekiguchi, Atsushi; Kotozaki, Yuka; Nakagawa, Seishu; Miyauchi, Carlos Makoto; Sassa, Yuko; Kawashima, Ryuta

    2014-08-01

    Multitasking (MT) constitutes engaging in two or more cognitive activities at the same time. MT-training improves performance on untrained MT tasks and alters the functional activity of the brain during MT. However, the effects of MT-training on neural mechanisms beyond MT-related functions are not known. We investigated the effects of 4 weeks of MT-training on regional gray matter volume (rGMV) and functional connectivity during rest (resting-FC) in young human adults. MT-training was associated with increased rGMV in three prefrontal cortical regions (left lateral rostral prefrontal cortex (PFC), dorsolateral PFC (DLPFC), and left inferior frontal junction), the left posterior parietal cortex, and the left temporal and lateral occipital areas as well as decreased resting-FC between the right DLPFC and an anatomical cluster around the ventral anterior cingulate cortex (ACC). Our findings suggest that participation in MT-training is as a whole associated with task-irrelevant plasticity (i.e., neural changes are not limited to certain specific task conditions) in regions and the network that are assumed to play roles in MT as well as diverse higher-order cognitive functions. We could not dissociate the effects of each task component and the diverse cognitive processes involved in MT because of the nature of the study, and these remain to be investigated. © 2013 The Authors. Human Brain Mapping Published by Wiley Periodicals, Inc.

  7. Structured chaos shapes spike-response noise entropy in balanced neural networks

    Directory of Open Access Journals (Sweden)

    Guillaume eLajoie

    2014-10-01

    Full Text Available Large networks of sparsely coupled, excitatory and inhibitory cells occur throughout the brain. For many models of these networks, a striking feature is that their dynamics are chaotic and thus, are sensitive to small perturbations. How does this chaos manifest in the neural code? Specifically, how variable are the spike patterns that such a network produces in response to an input signal? To answer this, we derive a bound for a general measure of variability -- spike-train entropy. This leads to important insights on the variability of multi-cell spike pattern distributions in large recurrent networks of spiking neurons responding to fluctuating inputs. The analysis is based on results from random dynamical systems theory and is complemented by detailed numerical simulations. We find that the spike pattern entropy is an order of magnitude lower than what would be extrapolated from single cells. This holds despite the fact that network coupling becomes vanishingly sparse as network size grows -- a phenomenon that depends on ``extensive chaos, as previously discovered for balanced networks without stimulus drive. Moreover, we show how spike pattern entropy is controlled by temporal features of the inputs. Our findings provide insight into how neural networks may encode stimuli in the presence of inherently chaotic dynamics.

  8. Reprogramming fibroblasts to neural-precursor-like cells by structured overexpression of pallial patterning genes.

    Science.gov (United States)

    Raciti, Marilena; Granzotto, Marilena; Duc, Minh Do; Fimiani, Cristina; Cellot, Giada; Cherubini, Enrico; Mallamaci, Antonello

    2013-11-01

    In this study, we assayed the capability of four genes implicated in embryonic specification of the cortico-cerebral field, Foxg1, Pax6, Emx2 and Lhx2, to reprogramme mouse embryonic fibroblasts towards neural identities. Lentivirus-mediated, TetON-dependent overexpression of Pax6 and Foxg1 transgenes specifically activated the neural stem cell (NSC) reporter Sox1-EGFP in a substantial fraction of engineered cells. The efficiency of this process was enhanced up to ten times by simultaneous inactivation of Trp53 and co-administration of a specific drug mix inhibiting HDACs, H3K27-HMTase and H3K4m2-demethylase. Remarkably, a fraction of the reprogrammed population expressed other NSC markers and retained its new identity, even after switching off the reprogramming transgenes. When transferred into a pro-differentiative environment, Pax6/Foxg1-overexpressing cells activated the neuronal marker Tau-EGFP. Frequency of Tau-EGFP positive cells was almost doubled upon delayed delivery of Emx2 and Lhx2 transgenes. A further improvement of the neuron-like cell output was achieved by inhibition of the BMP and TGFβ pathways. Tau-EGFP positive cells were able to generate action potentials upon injection of depolarizing current pulses, further indicating their neuron-like phenotype. © 2013.

  9. Morphology study of thoracic transverse processes and its significance in pedicle-rib unit screw fixation.

    Science.gov (United States)

    Cui, Xin-gang; Cai, Jin-fang; Sun, Jian-min; Jiang, Zhen-song

    2015-03-01

    Thoracic transverse process is an important anatomic structure of the spine. Several anatomic studies have investigated the adjacent structures of the thoracic transverse process. But there is still a blank on the morphology of the thoracic transverse processes. The purpose of the cadaveric study is to investigate the morphology of thoracic transverse processes and to provide morphology basis for the pedicle-rib unit (extrapedicular) screw fixation method. Forty-five adult dehydrated skeletons (T1-T10) were included in this study. The length, width, thickness, and the tilt angle (upward and backward) of the thoracic transverse process were measured. The data were then analyzed statistically. On the basis of the morphometric study, 5 fresh cadavers were used to place screws from transverse processes to the vertebral body in the thoracic spine, and then observed by the naked eye and on computed tomography scans. The lengths of thoracic transverse processes were between 16.63±1.59 and 18.10±1.95 mm; the longest was at T7, and the shortest was at T10. The widths of thoracic transverse processes were between 11.68±0.80 and 12.87±1.48 mm; the widest was at T3, and the narrowest was at T7. The thicknesses of thoracic transverse processes were between 7.86±1.24 and 10.78±1.35 mm; the thickest was at T1, and the thinnest was at T7. The upward tilt angles of thoracic transverse processes were between 24.9±3.1 and 3.0±1.56 degrees; the maximal upward tilt angle was at T1, and the minimal upward tilt angle was at T7. The upward tilt angles of T1 and T2 were obviously different from the other thoracic transverse processes (Pprocesses gradually increased from 24.5±2.91 degrees at T1 to 64.5±5.12 degrees at T10. The backward tilt angles were significantly different between each other, except between T5 and T6. In the validation study, screws were all placed successfully from transverse processes to the vertebrae of thoracic spine. The length, width, and thickness of the

  10. Eigenspectrum bounds for semirandom matrices with modular and spatial structure for neural networks.

    Science.gov (United States)

    Muir, Dylan R; Mrsic-Flogel, Thomas

    2015-04-01

    The eigenvalue spectrum of the matrix of directed weights defining a neural network model is informative of several stability and dynamical properties of network activity. Existing results for eigenspectra of sparse asymmetric random matrices neglect spatial or other constraints in determining entries in these matrices, and so are of partial applicability to cortical-like architectures. Here we examine a parameterized class of networks that are defined by sparse connectivity, with connection weighting modulated by physical proximity (i.e., asymmetric Euclidean random matrices), modular network partitioning, and functional specificity within the excitatory population. We present a set of analytical constraints that apply to the eigenvalue spectra of associated weight matrices, highlighting the relationship between connectivity rules and classes of network dynamics.

  11. Evaluation of hierarchical structured representations for QSPR studies of small molecules and polymers by recursive neural networks.

    Science.gov (United States)

    Bertinetto, Carlo; Duce, Celia; Micheli, Alessio; Solaro, Roberto; Starita, Antonina; Tiné, Maria Rosaria

    2009-04-01

    This paper reports some recent results from the empirical evaluation of different types of structured molecular representations used in QSPR analysis through a recursive neural network (RNN) model, which allows for their direct use without the need for measuring or computing molecular descriptors. This RNN methodology has been applied to the prediction of the properties of small molecules and polymers. In particular, three different descriptions of cyclic moieties, namely group, template and cyclebreak have been proposed. The effectiveness of the proposed method in dealing with different representations of chemical structures, either specifically designed or of more general use, has been demonstrated by its application to data sets encompassing various types of cyclic structures. For each class of experiments a test set with data that were not used for the development of the model was used for validation, and the comparisons have been based on the test results. The reported results highlight the flexibility of the RNN in directly treating different classes of structured input data without using input descriptors.

  12. A mathematical analysis of the effects of Hebbian learning rules on the dynamics and structure of discrete-time random recurrent neural networks.

    Science.gov (United States)

    Siri, Benoît; Berry, Hugues; Cessac, Bruno; Delord, Bruno; Quoy, Mathias

    2008-12-01

    We present a mathematical analysis of the effects of Hebbian learning in random recurrent neural networks, with a generic Hebbian learning rule, including passive forgetting and different timescales, for neuronal activity and learning dynamics. Previous numerical work has reported that Hebbian learning drives the system from chaos to a steady state through a sequence of bifurcations. Here, we interpret these results mathematically and show that these effects, involving a complex coupling between neuronal dynamics and synaptic graph structure, can be analyzed using Jacobian matrices, which introduce both a structural and a dynamical point of view on neural network evolution. Furthermore, we show that sensitivity to a learned pattern is maximal when the largest Lyapunov exponent is close to 0. We discuss how neural networks may take advantage of this regime of high functional interest.

  13. RISK FACTORS OF PEDICLE FIXATION INSTABILITY AT PATIENTS WITH DEGENERATIVE LUMBAR SPINE PATHOLOGY

    Directory of Open Access Journals (Sweden)

    A. E. Bokov

    2016-01-01

    Full Text Available Objective. To assess risk factors оf pedicle screw instability after decompression and fusion in patients with degenerative lumbar spine disease.Materials and methods. This is a prospective non-randomized study, the results of 130 surgical interventions with pedicle instrumentation in patients with degenerative lumbar spine diseases were studied. Minimal follow up period accounts for 18 months. Before intervention computed tomography (CT was applied and cancellous bone radiodensity was measured.Patients were treated with nerve root decompression and pedicle screw fixation stand-alone or with lumbar interbody fusion. During follow-up period computed tomography was applied and cases with evidence of pedicle screw loosening were detected. Radiodensity of cancellous bone, extension of fixation, extensiveness of decompression, application of interbody fusion, incomplete vertebra body reduction and heterogeneity of studied group were taken into account as potential risk factors of implant instability development. The correlation between pedicle screws loosening rate and mentioned predictors was estimated using logistic regression analysis.Results. Radiodensity of vertebra body cancellous bone getting decreased, the increase number of fixed levels and extensiveness of facet joints and ligaments resection are associated with the increased risk of a screw loosening development. Laminectomy, interbody fusion, altered biomechanics associated with incomplete vertebra body reduction and L5–S1 segment included into fixed zone did not have a significant influence on pedicle screws loosening rate. Bias related to heterogeneity of studied group was also insignificant. Goodness-of-fit of estimated general logistic regression model: № 2 = 67,57851; p < 0,0001. This model classified correctly 81,5% cases with sensitivity and specificity of 77,4% and 85,3% respectively.Conclusion. Radiodensity of a vertebra cancellous bone, number of fixed levels and

  14. Oxytocin receptor polymorphism and childhood social experiences shape adult personality, brain structure and neural correlates of mentalizing.

    Science.gov (United States)

    Schneider-Hassloff, H; Straube, B; Jansen, A; Nuscheler, B; Wemken, G; Witt, S H; Rietschel, M; Kircher, T

    2016-07-01

    The oxytocin system is involved in human social behavior and social cognition such as attachment, emotion recognition and mentalizing (i.e. the ability to represent mental states of oneself and others). It is shaped by social experiences in early life, especially by parent-infant interactions. The single nucleotid polymorphism rs53576 in the oxytocin receptor (OXTR) gene has been linked to social behavioral phenotypes. In 195 adult healthy subjects we investigated the interaction of OXTR rs53576 and childhood attachment security (CAS) on the personality traits "adult attachment style" and "alexithymia" (i.e. emotional self-awareness), on brain structure (voxel-based morphometry) and neural activation (fMRI) during an interactive mentalizing paradigm (prisoner's dilemma game; subgroup: n=163). We found that in GG-homozygotes, but not in A-allele carriers, insecure childhood attachment is - in adulthood - associated with a) higher attachment-related anxiety and alexithymia, b) higher brain gray matter volume of left amygdala and lower volumes in right superior parietal lobule (SPL), left temporal pole (TP), and bilateral frontal regions, and c) higher mentalizing-related neural activity in bilateral TP and precunei, and right middle and superior frontal gyri. Interaction effects of genotype and CAS on brain volume and/or function were associated with individual differences in alexithymia and attachment-related anxiety. Interactive effects were in part sexually dimorphic. The interaction of OXTR genotype and CAS modulates adult personality as well as brain structure and function of areas implicated in salience processing and mentalizing. Rs53576 GG-homozygotes are partially more susceptible to childhood attachment experiences than A-allele carriers. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Adolescent idiopathic scoliosis: sagital plane and low density pedicle screws

    Directory of Open Access Journals (Sweden)

    Rodrigo Augusto do Amaral

    2014-03-01

    Full Text Available OBJECTIVE: To examine the sagittal curves of patients treated with CD instrumentation using exclusively pedicle screws. METHODS: Image analysis of medical records of 27 patients (26 M and 1 F with a minimum follow-up of 6 months, who underwent surgical treatment in our service between January 2005 and December 2010. The curves were evaluated on coronal and sagittal planes, taking into account the potential correction of the technique. RESULTS: In the coronal plan the following curves were evaluated: proximal thoracic (TPx, main thoracic (TPp, and thoracolumbar; lumbar (TL, L, and the average flexibility was 52%, 52%, and 92% and the capacity of correction was 51%, 72%, and 64%, respectively. In the sagittal plane there was a mean increase in thoracic kyphosis (CT of 41% and an average reduction of lumbar lordosis (LL of 17%. Correlation analysis between variables showed Pearson coefficient of correlation of 0.053 and analysis of dispersion of R2 = <0.001. CONCLUSION: The method has shown satisfactory results with maintenance of kyphosis correction in patients with normal and hyper kyphotic deformities.

  16. Neural Network Enhanced Structure Determination of Osteoporosis, Immune System, and Radiation Repair Proteins Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a dual objective innovation that has valuable NASA applicability and tremendous commercial potential. The first innovation is the structure determination...

  17. Systematic analysis of non-structural protein features for the prediction of PTM function potential by artificial neural networks.

    Science.gov (United States)

    Dewhurst, Henry M; Torres, Matthew P

    2017-01-01

    Post-translational modifications (PTMs) provide an extensible framework for regulation of protein behavior beyond the diversity represented within the genome alone. While the rate of identification of PTMs has rapidly increased in recent years, our knowledge of PTM functionality encompasses less than 5% of this data. We previously developed SAPH-ire (Structural Analysis of PTM Hotspots) for the prioritization of eukaryotic PTMs based on function potential of discrete modified alignment positions (MAPs) in a set of 8 protein families. A proteome-wide expansion of the dataset to all families of PTM-bearing, eukaryotic proteins with a representational crystal structure and the application of artificial neural network (ANN) models demonstrated the broader applicability of this approach. Although structural features of proteins have been repeatedly demonstrated to be predictive of PTM functionality, the availability of adequately resolved 3D structures in the Protein Data Bank (PDB) limits the scope of these methods. In order to bridge this gap and capture the larger set of PTM-bearing proteins without an available, homologous structure, we explored all available MAP features as ANN inputs to identify predictive models that do not rely on 3D protein structural data. This systematic, algorithmic approach explores 8 available input features in exhaustive combinations (247 models; size 2-8). To control for potential bias in random sampling for holdback in training sets, we iterated each model across 100 randomized, sample training and testing sets-yielding 24,700 individual ANNs. The size of the analyzed dataset and iterative generation of ANNs represents the largest and most thorough investigation of predictive models for PTM functionality to date. Comparison of input layer combinations allows us to quantify ANN performance with a high degree of confidence and subsequently select a top-ranked, robust fit model which highlights 3,687 MAPs, including 10,933 PTMs with a high

  18. Spherical harmonics based descriptor for neural network potentials: Structure and dynamics of Au147 nanocluster

    Science.gov (United States)

    Jindal, Shweta; Chiriki, Siva; Bulusu, Satya S.

    2017-05-01

    We propose a highly efficient method for fitting the potential energy surface of a nanocluster using a spherical harmonics based descriptor integrated with an artificial neural network. Our method achieves the accuracy of quantum mechanics and speed of empirical potentials. For large sized gold clusters (Au147), the computational time for accurate calculation of energy and forces is about 1.7 s, which is faster by several orders of magnitude compared to density functional theory (DFT). This method is used to perform the global minimum optimizations and molecular dynamics simulations for Au147, and it is found that its global minimum is not an icosahedron. The isomer that can be regarded as the global minimum is found to be 4 eV lower in energy than the icosahedron and is confirmed from DFT. The geometry of the obtained global minimum contains 105 atoms on the surface and 42 atoms in the core. A brief study on the fluxionality in Au147 is performed, and it is concluded that Au147 has a dynamic surface, thus opening a new window for studying its reaction dynamics.

  19. Intra-operative computer navigation guided cervical pedicle screw insertion in thirty-three complex cervical spine deformities

    Directory of Open Access Journals (Sweden)

    S Rajasekaran

    2010-01-01

    Full Text Available Background: Cervical pedicle screw fixation is challenging due to the small osseous morphometrics and the close proximity of neurovascular elements. Computer navigation has been reported to improve the accuracy of pedicle screw placement. There are very few studies assessing its efficacy in the presence of deformity. Also cervical pedicle screw insertion in children has not been described before. We evaluated the safety and accuracy of Iso-C 3D-navigated pedicle screws in the deformed cervical spine. Materials and Methods: Thirty-three patients including 15 children formed the study group. One hundred and forty-five cervical pedicle screws were inserted using Iso-C 3D-based computer navigation in patients undergoing cervical spine stabilization for craniovertebral junction anomalies, cervico-thoracic deformities and cervical instabilities due to trauma, post-surgery and degenerative disorders. The accuracy and containment of screw placement was assessed from postoperative computerized tomography scans. Results: One hundred and thirty (89.7% screws were well contained inside the pedicles. Nine (6.1% Type A and six (4.2% Type B pedicle breaches were observed. In 136 levels, the screws were inserted in the classical description of pedicle screw application and in nine deformed vertebra, the screws were inserted in a non-classical fashion, taking purchase of the best bone stock. None of them had a critical breach. No patient had any neurovascular complications. Conclusion: Iso-C navigation improves the safety and accuracy of pedicle screw insertion and is not only successful in achieving secure pedicle fixation but also in identifying the best available bone stock for three-column bone fixation in altered anatomy. The advantages conferred by cervical pedicle screws can be extended to the pediatric population also.

  20. The contribution of an electronic conductivity device to the safety of pedicle screw insertion in scoliosis surgery.

    Science.gov (United States)

    Ovadia, Dror; Korn, Akiva; Fishkin, Michael; Steinberg, David M; Wientroub, Shlomo; Ofiram, Elisha

    2011-09-15

    Retrospective, controlled clinical study. To evaluate the contribution of an electronic conductivity device (ECD) to the safety of pedicle screw insertion in pediatric scoliosis surgery. The implantation of pedicle screws in spinal deformity correction surgery has evolved into the currently predominant fixation technique. Methodologies for optimizing placement of pedicle screws are fluoroscopy, electromyography, and intraoperative image-based navigation. A hand-held ECD was recently introduced. Pedicle screw insertion was analyzed in 248 pediatric scoliosis patients (idiopathic, congenital, neuromuscular, syndromatic). Group I included 150 procedures without the aid of the ECD and group II included 98 ECD-aided procedures. The two groups were matched by age, sex, etiology, Cobb angle, and surgical criteria. Data on screw position and concomitant neuromonitoring alarms were compared. Group I consisted of patients operated with both the hybrid construct and pedicle screw instrumentation, while group II consisted of patients operated solely with pedicle screws. Both groups were operated on by a single surgeon with the same neurophysiologic methodology. Clinically relevant misplaced pedicle screws were established by intraoperative monitoring alarms concomitant with pedicle screw insertion. A total of 1270 pedicle screw placements were analyzed in group I and compared with 1400 pedicle screw placements in group II. Neuromonitoring alarms concomitant with screw placement occurred in 10 procedures in group I (6.6%) compared with 3 in group II (3.0%). The contribution of the electronic device to reducing the number of neurophysiologic alarms was significant (P = 0.048, Fisher exact test). Nine of the 13 monitoring alarms (69%) were associated with implantation adjacent to the apex of the spinal curve. The use of an ECD significantly reduced the incidence of clinically relevant misplaced screws in a variety of scoliosis patients, thereby increasing the safety of pedicle

  1. Neural Mechanisms of Verb Argument Structure Processing in Agrammatic Aphasic and Healthy Age-Matched Listeners

    Science.gov (United States)

    Thompson, Cynthia K.; Bonakdarpour, Borna; Fix, Stephen F.

    2010-01-01

    Processing of lexical verbs involves automatic access to argument structure entries entailed within the verb's representation. Recent neuroimaging studies with young normal listeners suggest that this involves bilateral posterior peri-sylvian tissue, with graded activation in these regions on the basis of argument structure complexity. The aim of…

  2. Individualized 3D printing navigation template for pedicle screw fixation in upper cervical spine.

    Directory of Open Access Journals (Sweden)

    Fei Guo

    Full Text Available Pedicle screw fixation in the upper cervical spine is a difficult and high-risk procedure. The screw is difficult to place rapidly and accurately, and can lead to serious injury of spinal cord or vertebral artery. The aim of this study was to design an individualized 3D printing navigation template for pedicle screw fixation in the upper cervical spine.Using CT thin slices data, we employed computer software to design the navigation template for pedicle screw fixation in the upper cervical spine (atlas and axis. The upper cervical spine models and navigation templates were produced by 3D printer with equal proportion, two sets for each case. In one set (Test group, pedicle screws fixation were guided by the navigation template; in the second set (Control group, the screws were fixed under fluoroscopy. According to the degree of pedicle cortex perforation and whether the screw needed to be refitted, the fixation effects were divided into 3 types: Type I, screw is fully located within the vertebral pedicle; Type II, degree of pedicle cortex perforation is 1 mm or with the poor internal fixation stability and in need of renovation. Type I and Type II were acceptable placements; Type III placements were unacceptable.A total of 19 upper cervical spine and 19 navigation templates were printed, and 37 pedicle screws were fixed in each group. Type I screw-placements in the test group totaled 32; Type II totaled 3; and Type III totaled 2; with an acceptable rate of 94.60%. Type I screw placements in the control group totaled 23; Type II totaled 3; and Type III totaled 11, with an acceptable rate of 70.27%. The acceptability rate in test group was higher than the rate in control group. The operation time and fluoroscopic frequency for each screw were decreased, compared with control group.The individualized 3D printing navigation template for pedicle screw fixation is easy and safe, with a high success rate in the upper cervical spine surgery.

  3. Comparison Study between Conventional Sequence and Slice-Encoding Metal Artifact Correction (SEMAC in the Diagnosis of Postoperative Complications in Patients Receiving Lumbar Inter-Body Fusion and Pedicle Screw Fixation Surgery.

    Directory of Open Access Journals (Sweden)

    Sol Bee Han

    Full Text Available Slice-Encoding Metal Artifact Correction (SEMAC sequence is one of the metal artifact reduction techniques of anatomical structure, but there has been no report about evaluation of post-operative complications. The purpose of this article is to compare the anatomical visibility between fast spin echo (FSE and FSE-SEMAC and to evaluate the additional value of FSE-SEMAC in diagnostic confidence of the complications.We conducted a retrospective study with 54 patients who received lumbar spinal surgery and MR images including FSE-SEMAC. For the semi-quantitative evaluation, the visibility of anatomical structures (neural foramen, bone-inter-body cage interface, central canal, nerve root in epidural space, back muscle, and bone-pedicle screw interface was evaluated. For qualitative evaluation, we evaluated FSE and FSE with FSE-SEMAC independently, and recorded the diagnostic confidence level of post-operative complications. Generalized estimating equation regression analysis was used for statistical analysis, and a weighted kappa was used for inter-observer agreement.Scores of 6 imaging findings with FSE-SEMAC were significantly higher than that of FSE (P-value < .0001. Inter-observer agreements show good reliability (weighted kappa = 0.45-0.75. Both reviewers deemed 37 (reviewer 1 or 19 more (reviewer 2 post-operative complications with FSE plus FSE-SEMAC, compared to FSE only. Except for central canal stenosis (P-value = .2408, diagnostic confidence level for other post-operative complications were significantly higher with FSE plus FSE-SEMAC (P-value = .0000 than FSE.FSE-SEMAC significantly reduces image distortion, compared to FSE sequence in 3.0-T MR. Also, diagnostic confidence for post-operative complications was higher when FSE with additional FSE-SEMAC compared to FSE only.

  4. Efficacy and accuracy of a novel rapid prototyping drill template for cervical pedicle screw placement.

    Science.gov (United States)

    Lu, Sheng; Xu, Yong Q; Chen, Guo P; Zhang, Yuan Z; Lu, Di; Chen, Yu B; Shi, Ji H; Xu, Xing M

    2011-01-01

    To develop and validate the efficacy and accuracy of a novel drill template for cervical pedicle instrumentation. A CT scan of the cervical vertebrae was performed, and a 3D model of the vertebrae was reconstructed using MIMICS 10.01 software. The 3D vertebral model was then exported in STL format, and opened in a workstation running UGS Imageware 12.0 software to determine the optimal pedicle screw size and orientation. A virtual navigational template was established according to the laminar anatomic trait, and physical navigational templates were manufactured using rapid prototyping. The navigational templates were used intraoperatively to assist in the placement of cervical pedicle screws. In all, 84 pedicle screws were placed, and the accuracy of screw placement was confirmed with postoperative X-rays and CT scans. Eighty-two screws were rated as Grade 0, 2 as Grade 1, and no screws as Grade 2 or 3. Hence, safer screw positioning was accomplished with the drill template technique. This study demonstrates a patient-specific template technique that is easy to use, can simplify the surgical act, and generates highly accurate cervical pedicle screw placement. The advantages of this technology over traditional techniques are that it enables planning of the screw trajectory to be completed prior to surgery, and that the screw can be sized to fit the patient's anatomy.

  5. Human neural progenitor cells decrease photoreceptor degeneration, normalize opsin distribution and support synapse structure in cultured porcine retina.

    Science.gov (United States)

    Mollick, Tanzina; Mohlin, Camilla; Johansson, Kjell

    2016-09-01

    Retinal neurodegenerative disorders like retinitis pigmentosa, age-related macular degeneration, diabetic retinopathy and retinal detachment decrease retinal functionality leading to visual impairment. The pathological events are characterized by photoreceptor degeneration, synaptic disassembly, remodeling of postsynaptic neurons and activation of glial cells. Despite intense research, no effective treatment has been found for these disorders. The current study explores the potential of human neural progenitor cell (hNPC) derived factors to slow the degenerative processes in adult porcine retinal explants. Retinas were cultured for 3 days with or without hNPCs as a feeder layer and investigated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), immunohistochemical, western blot and quantitative real time-polymerase chain reaction (qRT-PCR) techniques. TUNEL showed that hNPCs had the capacity to limit photoreceptor cell death. Among cone photoreceptors, hNPC coculture resulted in better maintenance of cone outer segments and reduced opsin mislocalization. Additionally, maintained synaptic structural integrity and preservation of second order calbindin positive horizontal cells was also observed. However, Müller cell gliosis only seemed to be alleviated in terms of reduced Müller cell density. Our observations indicate that at 3 days of coculture, hNPC derived factors had the capacity to protect photoreceptors, maintain synaptic integrity and support horizontal cell survival. Human neural progenitor cell applied treatment modalities may be an effective strategy to help maintain retinal functionality in neurodegenerative pathologies. Whether hNPCs can independently hinder Müller cell gliosis by utilizing higher concentrations or by combination with other pharmacological agents still needs to be determined. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. What Is Neural Plasticity?

    Science.gov (United States)

    von Bernhardi, Rommy; Bernhardi, Laura Eugenín-von; Eugenín, Jaime

    2017-01-01

    "Neural plasticity" refers to the capacity of the nervous system to modify itself, functionally and structurally, in response to experience and injury. As the various chapters in this volume show, plasticity is a key component of neural development and normal functioning of the nervous system, as well as a response to the changing environment, aging, or pathological insult. This chapter discusses how plasticity is necessary not only for neural networks to acquire new functional properties, but also for them to remain robust and stable. The article also reviews the seminal proposals developed over the years that have driven experiments and strongly influenced concepts of neural plasticity.

  7. Learning the Relationship between the Primary Structure of HIV Envelope Glycoproteins and Neutralization Activity of Particular Antibodies by Using Artificial Neural Networks

    Science.gov (United States)

    Buiu, Cătălin; Putz, Mihai V.; Avram, Speranta

    2016-01-01

    The dependency between the primary structure of HIV envelope glycoproteins (ENV) and the neutralization data for given antibodies is very complicated and depends on a large number of factors, such as the binding affinity of a given antibody for a given ENV protein, and the intrinsic infection kinetics of the viral strain. This paper presents a first approach to learning these dependencies using an artificial feedforward neural network which is trained to learn from experimental data. The results presented here demonstrate that the trained neural network is able to generalize on new viral strains and to predict reliable values of neutralizing activities of given antibodies against HIV-1. PMID:27727189

  8. Musical intervention enhances infants' neural processing of temporal structure in music and speech

    National Research Council Canada - National Science Library

    Zhao, T Christina; Kuhl, Patricia K

    2016-01-01

    .... The intervention targeted temporal structure learning using triple meter in music (e.g., waltz), which is difficult for infants, and it incorporated key characteristics of typical infant music classes to maximize...

  9. Musical intervention enhances infants' neural processing of temporal structure in music and speech

    National Research Council Canada - National Science Library

    Zhao, T Christina; Kuhl, Patricia K

    2016-01-01

    .... The intervention targeted temporal structure learning using triple meter in music (e.g., waltz), which is difficult for infants, and it incorporated key characteristics of typical infant music classes to maximize learning (e.g...

  10. Are pedicle screw perforation rates influenced by distance from the reference frame in multilevel registration using a computed tomography-based navigation system in the setting of scoliosis?

    Science.gov (United States)

    Uehara, Masashi; Takahashi, Jun; Ikegami, Shota; Kuraishi, Shugo; Shimizu, Masayuki; Futatsugi, Toshimasa; Oba, Hiroki; Kato, Hiroyuki

    2017-04-01

    Pedicle screw fixation is commonly employed for the surgical correction of scoliosis but carries a risk of serious neurovascular or visceral structure events during screw insertion. To avoid these complications, we have been using a computed tomography (CT)-based navigation system during pedicle screw placement. As this could also prolong operation time, multilevel registration for pedicle screw insertion for posterior scoliosis surgery was developed to register three consecutive vertebrae in a single time with CT-based navigation. The reference frame was set either at the caudal end of three consecutive vertebrae or at one or two vertebrae inferior to the most caudal registered vertebra, and then pedicle screws were inserted into the three consecutive registered vertebrae and into the one or two adjacent vertebrae. This study investigated the perforation rates of vertebrae at zero, one, two, three, or four or more levels above or below the vertebra at which the reference frame was set. This is a retrospective, single-center, single-surgeon study. One hundred sixty-one scoliosis patients who had undergone pedicle screw fixation were reviewed. Screw perforation rates were evaluated by postoperative CT. We evaluated 161 scoliosis patients (34 boys and 127 girls; mean±standard deviation age: 14.6±2.8 years) who underwent pedicle screw fixation guided by a CT-based navigation system between March 2006 and December 2015. A total of 2,203 pedicle screws were inserted into T2-L5 using multilevel registration with CT-based navigation. The overall perforation rates for Grade 1, 2, or 3, Grade 2 or 3 (major perforations), and Grade 3 perforations (violations) were as follows: vertebrae at which the reference frame was set: 15.9%, 6.1%, and 2.5%; one vertebra above or below the reference frame vertebra: 16.5%, 4.0%, and 1.2%; two vertebrae above or below the reference frame vertebra: 20.7%, 8.7%, and 2.3%; three vertebrae above or below the reference frame vertebra: 23

  11. GIAO C-H COSY Simulations Merged with Artificial Neural Networks Pattern Recognition Analysis. Pushing the Structural Validation a Step Forward.

    Science.gov (United States)

    Zanardi, María M; Sarotti, Ariel M

    2015-10-02

    The structural validation problem using quantum chemistry approaches (confirm or reject a candidate structure) has been tackled with artificial neural network (ANN) mediated multidimensional pattern recognition from experimental and calculated 2D C-H COSY. In order to identify subtle errors (such as regio- or stereochemical), more than 400 ANNs have been built and trained, and the most efficient in terms of classification ability were successfully validated in challenging real examples of natural product misassignments.

  12. Biomechanical efficacy of monoaxial or polyaxial pedicle screw and additional screw insertion at the level of fracture, in lumbar burst fracture: An experimental study

    Directory of Open Access Journals (Sweden)

    Hongwei Wang

    2012-01-01

    Conclusions: The addition of intermediate screws at the level of a burst fracture significantly increased the stability of short-segment pedicle screw fixation in both the MPS and PPS groups. However, in short-segment fixation group, monoaxial pedicle screw exhibited more stability in flexion and extension than the polyaxial pedicle screw.

  13. Structure Crack Identification Based on Surface-mounted Active Sensor Network with Time-Domain Feature Extraction and Neural Network

    Directory of Open Access Journals (Sweden)

    Chunling DU

    2012-03-01

    Full Text Available In this work the condition of metallic structures are classified based on the acquired sensor data from a surface-mounted piezoelectric sensor/actuator network. The structures are aluminum plates with riveted holes and possible crack damage at these holes. A 400 kHz sine wave burst is used as diagnostic signals. The combination of time-domain S0 waves from received sensor signals is directly used as features and preprocessing is not needed for the dam age detection. Since the time sequence of the extracted S0 has a high dimension, principal component estimation is applied to reduce its dimension before entering NN (neural network training for classification. An LVQ (learning vector quantization NN is used to classify the conditions as healthy or damaged. A number of FEM (finite element modeling results are taken as inputs to the NN for training, since the simulated S0 waves agree well with the experimental results on real plates. The performance of the classification is then validated by using these testing results.

  14. Structural Basis for Partial Redundancy in a Class of Transcription Factors, the LIM Homeodomain Proteins, in Neural Cell Type Specification*

    Science.gov (United States)

    Gadd, Morgan S.; Bhati, Mugdha; Jeffries, Cy M.; Langley, David B.; Trewhella, Jill; Guss, J. Mitchell; Matthews, Jacqueline M.

    2011-01-01

    Combinations of LIM homeodomain proteins form a transcriptional “LIM code” to direct the specification of neural cell types. Two paralogous pairs of LIM homeodomain proteins, LIM homeobox protein 3/4 (Lhx3/Lhx4) and Islet-1/2 (Isl1/Isl2), are expressed in developing ventral motor neurons. Lhx3 and Isl1 interact within a well characterized transcriptional complex that triggers motor neuron development, but it was not known whether Lhx4 and Isl2 could participate in equivalent complexes. We have identified an Lhx3-binding domain (LBD) in Isl2 based on sequence homology with the Isl1LBD and show that both Isl2LBD and Isl1LBD can bind each of Lhx3 and Lhx4. X-ray crystal- and small-angle x-ray scattering-derived solution structures of an Lhx4·Isl2 complex exhibit many similarities with that of Lhx3·Isl1; however, structural differences supported by mutagenic studies reveal differences in the mechanisms of binding. Differences in binding have implications for the mode of exchange of protein partners in transcriptional complexes and indicate a divergence in functions of Lhx3/4 and Isl1/2. The formation of weaker Lhx·Isl complexes would likely be masked by the availability of the other Lhx·Isl complexes in postmitotic motor neurons. PMID:22025611

  15. Structure and Mutagenesis of Neural Cell Adhesion Molecule Domains Evidence for Flexibility in the Placement of Polysialic Acid Attachment Sites

    Energy Technology Data Exchange (ETDEWEB)

    Foley, Deirdre A.; Swartzentruber, Kristin G.; Lavie, Arnon; Colley, Karen J. (UICM)

    2010-11-09

    The addition of {alpha}2,8-polysialic acid to the N-glycans of the neural cell adhesion molecule, NCAM, is critical for brain development and plays roles in synaptic plasticity, learning and memory, neuronal regeneration, and the growth and invasiveness of cancer cells. Our previous work indicates that the polysialylation of two N-glycans located on the fifth immunoglobulin domain (Ig5) of NCAM requires the presence of specific sequences in the adjacent fibronectin type III repeat (FN1). To understand the relationship of these two domains, we have solved the crystal structure of the NCAM Ig5-FN1 tandem. Unexpectedly, the structure reveals that the sites of Ig5 polysialylation are on the opposite face from the FN1 residues previously found to be critical for N-glycan polysialylation, suggesting that the Ig5-FN1 domain relationship may be flexible and/or that there is flexibility in the placement of Ig5 glycosylation sites for polysialylation. To test the latter possibility, new Ig5 glycosylation sites were engineered and their polysialylation tested. We observed some flexibility in glycosylation site location for polysialylation and demonstrate that the lack of polysialylation of a glycan attached to Asn-423 may be in part related to a lack of terminal processing. The data also suggest that, although the polysialyltransferases do not require the Ig5 domain for NCAM recognition, their ability to engage with this domain is necessary for polysialylation to occur on Ig5 N-glycans.

  16. Evolvable Neural Software System

    Science.gov (United States)

    Curtis, Steven A.

    2009-01-01

    The Evolvable Neural Software System (ENSS) is composed of sets of Neural Basis Functions (NBFs), which can be totally autonomously created and removed according to the changing needs and requirements of the software system. The resulting structure is both hierarchical and self-similar in that a given set of NBFs may have a ruler NBF, which in turn communicates with other sets of NBFs. These sets of NBFs may function as nodes to a ruler node, which are also NBF constructs. In this manner, the synthetic neural system can exhibit the complexity, three-dimensional connectivity, and adaptability of biological neural systems. An added advantage of ENSS over a natural neural system is its ability to modify its core genetic code in response to environmental changes as reflected in needs and requirements. The neural system is fully adaptive and evolvable and is trainable before release. It continues to rewire itself while on the job. The NBF is a unique, bilevel intelligence neural system composed of a higher-level heuristic neural system (HNS) and a lower-level, autonomic neural system (ANS). Taken together, the HNS and the ANS give each NBF the complete capabilities of a biological neural system to match sensory inputs to actions. Another feature of the NBF is the Evolvable Neural Interface (ENI), which links the HNS and ANS. The ENI solves the interface problem between these two systems by actively adapting and evolving from a primitive initial state (a Neural Thread) to a complicated, operational ENI and successfully adapting to a training sequence of sensory input. This simulates the adaptation of a biological neural system in a developmental phase. Within the greater multi-NBF and multi-node ENSS, self-similar ENI s provide the basis for inter-NBF and inter-node connectivity.

  17. Subcutaneous pedicled V-Y advancement flap for surgical reconstruction of the auricle of the ear.

    Science.gov (United States)

    González-Sixto, B; Pérez-Bustillo, A; Otero-Rivas, M M; Rodríguez-Prieto, M Á

    2014-05-01

    The subcutaneous pedicled V-Y advancement flap is useful for the repair of small and medium-sized defects in areas where it is easy to obtain a good subcutaneous pedicle (upper lip, cheek, eyebrow, and nasal tip and ala). The almost complete absence of subcutaneous tissue on the anterior aspect of the auricle of the ear can limit the use of this approach in this region. We present 4 patients in whom subcutaneous pedicled V-Y advancement flaps were used to repair surgical defects of the helix, scaphoid fossa, and antitragus, achieving a good functional and aesthetic result in all cases. Copyright © 2012 Elsevier España, S.L. and AEDV. All rights reserved.

  18. The efficacy of pedicle screw instrument in treatment of irreducible atlantoaxial dislocation.

    Science.gov (United States)

    Zhai, Ming-Yu; Wang, Chun-Ping; Liu, Feng; Liu, Yu-Qiang; Zhang, Peng

    2015-09-01

    To explore the effect of pedicle screw instrument in treatment of irreducible atlantoaxial dislocation. From June 2003 to February 2009, 14 cases of atlas dislocation with upper cervical cord compression were enrolled and anterior transoral soft tissue release combined with posterior reduction and pedicle screw fixation were performed. CT, MRI and radiograph were used preoperatively, and screw placement and bone graft were administered in all cases intraoperatively. Cervical collars were used for 3 months. Screws were successfully placed in atlas in all cases. The average follow-up period was 18 months. Bone fusion was observed in all cases without the following complications: neurologic symptoms, internal fixation failure and redislocation. Neurological recovery was observed in all 14 cases. Pedicle screw instrument has the following advantages in atlas and axis injury treatment: direct screw placement, short-segment fusion, intraoperative reduction and high fusion rate, which should be a better surgical method for the treatment of atlantoaxial dislocation.

  19. A Computed Tomography-Based Comparison of Abnormal Vertebrae Pedicles Between Dystrophic and Nondystrophic Scoliosis in Neurofibromatosis Type 1.

    Science.gov (United States)

    Li, Ying; Luo, Ming; Wang, Wengang; Shen, Mingkui; Xu, Genzhong; Gao, Jianbo; Xia, Lei

    2017-10-01

    To explore the prevalence and distribution of abnormal vertebral pedicles in scoliosis secondary to neurofibromatosis type 1 (NF1-S) and to compare the abnormal vertebrae pedicles between dystrophic and nondystrophic scoliosis. Using computed tomography images, we carefully measured 2652 vertebral pedicles from 56 patients with NF1-S with dystrophic scoliosis and 22 patients with NF1-S with nondystrophic scoliosis. Pedicle morphology was classified as follows: type A, a cancellous channel of >4 mm; type B, a cancellous channel of 2 to 4 mm; type C, a cancellous channel of scoliosis compared with nondystrophic scoliosis (70% vs. 59%, P scoliosis compared with nondystrophic ones. The described pedicle classification system could serve as an objective tool to guide preoperative assessment. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Biomechanical comparison of sagittal-parallel versus non-parallel pedicle screw placement.

    Science.gov (United States)

    Farshad, Mazda; Farshad-Amacker, Nadja A; Bachmann, Elias; Snedeker, Jess G; Schmid, Samuel L

    2014-11-01

    While convergent placement of pedicle screws in the axial plane is known to be more advantageous biomechanically, surgeons intuitively aim toward a parallel placement of screws in the sagittal plane. It is however not clear whether parallel placement of screws in the sagittal plane is biomechanically superior to a non-parallel construct. The hypothesis of this study is that sagittal non-parallel pedicle screws do not have an inferior initial pull-out strength compared to parallel placed screws. The established lumbar calf spine model was used for determination of pull-out strength in parallel and non-parallel intersegmental pedicle screw constructs. Each of six lumbar calf spines (L1-L6) was divided into three levels: L1/L2, L3/L4 and L5/L6. Each segment was randomly instrumented with pedicle screws (6/45 mm) with either the standard technique of sagittal parallel or non-parallel screw placement, respectively, under fluoroscopic control. CT was used to verify the intrapedicular positioning of all screws. The maximum pull-out forces and type of failure were registered and compared between the groups. The pull-out forces were 5,394 N (range 4,221 N to 8,342 N) for the sagittal non-parallel screws and 5,263 N (range 3,589 N to 7,554 N) for the sagittal-parallel screws (p = 0.838). Interlevel comparisons also showed no statistically significant differences between the groups with no relevant difference in failure mode. Non-parallel pedicle screws in the sagittal plane have at least equal initial fixation strength compared to parallel pedicle screws in the setting of the here performed cadaveric calf spine experiments.

  1. Trans-Endplate Pedicle Pillar System in Unstable Spinal Burst Fractures: Design, Technique, and Mechanical Evaluation.

    Directory of Open Access Journals (Sweden)

    Chunfeng Zhao

    Full Text Available Short-segment pedicle screw instrumentation (SSPI is used for unstable burst fractures to correct deformity and stabilize the spine for fusion. However, pedicle screw loosening, pullout, or breakage often occurs due to the large moment applied during spine motion, leading to poor outcomes. The purpose of this study was to test the ability of a newly designed device, the Trans-Endplate Pedicle Pillar System (TEPPS, to enhance SSPI rigidity and decrease the screw bending moment with a simple posterior approach.Six human cadaveric spines (T11-L3 were harvested. A burst fracture was created at L1, and the SSPI (Moss Miami System was used for SSPI fixation. Strain gauge sensors were mounted on upper pedicle screws to measure screw load bearing. Segmental motion (T12-L2 was measured under pure moment of 7.5 Nm. The spine was tested sequentially under 4 conditions: intact; first SSPI alone (SSPI-1; SSPI+TEPPS; and second SSPI alone (SSPI-2.SSPI+TEPPS increased fixation rigidity by 41% in flexion/extension, 28% in lateral bending, and 37% in axial rotation compared with SSPI-1 (P<0.001, and it performed even better compared to SSPI-2 (P<0.001 for all. Importantly, the bending moment on the pedicle screws for SSPI+TEPPS was significantly decreased 63% during spine flexion and 47% in lateral bending (p<0.001.TEPPS provided strong anterior support, enhanced SSPI fixation rigidity, and dramatically decreased the load on the pedicle screws. Its biomechanical benefits could potentially improve fusion rates and decrease SSPI instrumentation failure.

  2. Safety and esthetic outcomes of therapeutic mammoplasty using medial pedicle for early breast cancer

    Science.gov (United States)

    Roshdy, Sameh; Hussein, Osama; Khater, Ashraf; Zuhdy, Mohammad; El-Hadaad, Hend A; Farouk, Omar; Senbel, Ahmad; Fathi, Adel; Hamed, Emadeldeen; Denewer, Adel

    2015-01-01

    Background Although therapeutic mammoplasty (TM) was introduced for treatment of localized ductal carcinoma in situ and invasive breast carcinoma (stages I and II) in females with large breast size, the suitability of medial pedicle TM for treatment of breast tumors at different locations has not been established. The objective of this study was to assess the safety and esthetic outcome of medial pedicle TM for breast tumors at different locations. Methods The study was conducted from February 2012 to July 2014. Consecutive patients with early breast carcinoma with medium- and large-sized breasts, with or without ptosis, who were offered medial pedicle TM were included in the study. Patients who were not candidates for breast-conserving surgery or those with tumors located along the medial pedicle were excluded. All patients received immediate postoperative adjuvant chemoradiotherapy. Results Thirty patients with a mean age of 48.5 years received medial pedicle TM in the breast harboring the tumor or, additionally, the other breast (N=14). The tumors were in the upper (60.0%), lower (26.7%), and lateral (13.3%) quadrants. Minor complications occurred in five cases (5/30, 16.7%) in the ipsilateral and in two (2/14, 14.3%) contralateral breasts. No wound dehiscence or areolar necrosis was recorded. A total of 22 (73.3%) patients were scored as excellent cosmesis. After a median follow-up of 20 months, no locoregional recurrence or distant metastases were observed. Conclusion TM using a medial pedicle is a safe and appealing technique among women with tumors at different locations. PMID:26185469

  3. The short- and ultrashort-pedicle deep inferior epigastric artery perforator flap in breast reconstruction.

    Science.gov (United States)

    Colohan, Shannon; Maia, Munique; Langevin, Claude Jean; Donfrancesco, Andrea; Shirvani, Arash; Trussler, Andrew P; Saint-Cyr, Michel

    2012-02-01

    Breast reconstruction using the deep inferior epigastric perforator (DIEP) flap is becoming more common and can help reduce donor site morbidity. The authors proposed that dissection of the deep inferior epigastric artery (DIEA) and vein (DIEV) to their external iliac source may not be required for safe flap transfer. Sixteen whole fresh cadaveric hemiabdomens were used to dissect transverse abdominal-based flaps. Latex injection of the DIEA system was carried out, and the diameters of the DIEA/DIEV vessels were assessed at various points along the course of the pedicle from the origin to the perforator. A clinical study of 26 patients who underwent a short and ultrashort pedicle DIEP flaps was carried out. The average DIEA and DIEV vessel diameters were relatively similar from the external iliac origin to a point just caudal to the bifurcation. At the lateral rectus edge, the average DIEA diameter was 3.2 mm, and the DIEV diameter was 3.1 mm. The average pedicle length obtained with classic DIEP dissection was 16.9 cm, short-pedicle DIEP dissection 10.4 cm, ultrashort technique 8.1 cm, and free TRAM technique 6.5 cm. Venous injection study demonstrated rich venous interconnections between both venae comitantes. In their clinical study, the authors were able to achieve average pedicle lengths of 11.0 cm when transecting cranial to the lateral edge of the rectus, with average diameters of 2.5 mm (artery) and 2.9 mm (vein). Transection of the DIEA/DIEV pedicle at the lateral rectus edge or more proximally is safe and can help reduce operative time and donor-site morbidity. Therapeutic, IV.

  4. Functional and structural aging of the speech sensorimotor neural system: fMRI evidence

    Science.gov (United States)

    Tremblay, Pascale; Dick, Anthony Steven; Small, Steven L.

    2013-01-01

    The ability to perceive and produce speech undergoes important changes in late adulthood. The goal of the present study was to characterize functional and structural age-related differences in the cortical network supporting speech perception and production using magnetic resonance imaging, as well as the relationship between functional and structural age-related changes occurring in this network. We asked young and older adults to (1) observe videos of a speaker producing single words (perception), and (B) observe and repeat the words produced (production). Results show a widespread bilateral network of brain activation for Perception and Production that was uncorrelated with age. In addition, several regions did show age-related change (auditory cortex, planum temporale, superior temporal sulcus, premotor cortices, SMA-proper). Examination of the relationship between brain signal and regional and global gray matter volume and cortical thickness revealed a complex set of relationships between structure and function, with some regions showing a relationship between structure and function and not. The present results provide novel findings about the neurobiology of aging and verbal communication. PMID:23523270

  5. Prediction of protein structural features by use of artificial neural networks

    DEFF Research Database (Denmark)

    Petersen, Bent

    . There is a huge over-representation of DNA sequences when comparing the amount of experimentally verified proteins with the amount of DNA sequences. The academic and industrial research community therefore has to rely on structure predictions instead of waiting for the time consuming experimentally determined...

  6. Learning to Perceive Structure from Motion and Neural Plasticity in Patients with Alzheimer's Disease

    Science.gov (United States)

    Kim, Nam-Gyoon; Park, Jong-Hee

    2010-01-01

    Recent research has demonstrated that Alzheimer's disease (AD) affects the visual sensory pathways, producing a variety of visual deficits, including the capacity to perceive structure-from-motion (SFM). Because the sensory areas of the adult brain are known to retain a large degree of plasticity, the present study was conducted to explore whether…

  7. Bayesian inference of Earth's radial seismic structure from body-wave traveltimes using neural networks

    NARCIS (Netherlands)

    de Wit, R.W.L.; Valentine, A.P.; Trampert, J.

    2013-01-01

    How do body-wave traveltimes constrain the Earth's radial (1-D) seismic structure? Existing 1-D seismological models underpin 3-D seismic tomography and earthquake location algorithms. It is therefore crucial to assess the quality of such 1-D models, yet quantifying uncertainties in seismological

  8. Revisiting Earth's radial seismic structure using a Bayesian neural network approach

    NARCIS (Netherlands)

    de Wit, R.W.L.

    2015-01-01

    The gross features of seismic observations can be explained by relatively simple spherically symmetric (1-D) models of wave velocities, density and attenuation, which describe the Earth's average(radial) structure. 1-D earth models are often used as a reference for studies on Earth's thermo-chemical

  9. Functional and structural aging of the speech sensorimotor neural system: functional magnetic resonance imaging evidence.

    Science.gov (United States)

    Tremblay, Pascale; Dick, Anthony S; Small, Steven L

    2013-08-01

    The ability to perceive and produce speech undergoes important changes in late adulthood. The goal of the present study was to characterize functional and structural age-related differences in the cortical network that support speech perception and production, using magnetic resonance imaging, as well as the relationship between functional and structural age-related changes occurring in this network. We asked young and older adults to observe videos of a speaker producing single words (perception), and to observe and repeat the words produced (production). Results show a widespread bilateral network of brain activation for Perception and Production that was not correlated with age. In addition, several regions did show age-related change (auditory cortex, planum temporale, superior temporal sulcus, premotor cortices, SMA-proper). Examination of the relationship between brain signal and regional and global gray matter volume and cortical thickness revealed a complex set of relationships between structure and function, with some regions showing a relationship between structure and function and some not. The present results provide novel findings about the neurobiology of aging and verbal communication. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Neural correlates of emotional personality: a structural and functional magnetic resonance imaging study.

    Directory of Open Access Journals (Sweden)

    Stefan Koelsch

    Full Text Available Studies addressing brain correlates of emotional personality have remained sparse, despite the involvement of emotional personality in health and well-being. This study investigates structural and functional brain correlates of psychological and physiological measures related to emotional personality. Psychological measures included neuroticism, extraversion, and agreeableness scores, as assessed using a standard personality questionnaire. As a physiological measure we used a cardiac amplitude signature, the so-called E κ value (computed from the electrocardiogram which has previously been related to tender emotionality. Questionnaire scores and E κ values were related to both functional (eigenvector centrality mapping, ECM and structural (voxel-based morphometry, VBM neuroimaging data. Functional magnetic resonance imaging (fMRI data were obtained from 22 individuals (12 females while listening to music (joy, fear, or neutral music. ECM results showed that agreeableness scores correlated with centrality values in the dorsolateral prefrontal cortex, the anterior cingulate cortex, and the ventral striatum (nucleus accumbens. Individuals with higher E κ values (indexing higher tender emotionality showed higher centrality values in the subiculum of the right hippocampal formation. Structural MRI data from an independent sample of 59 individuals (34 females showed that neuroticism scores correlated with volume of the left amygdaloid complex. In addition, individuals with higher E κ showed larger gray matter volume in the same portion of the subiculum in which individuals with higher E κ showed higher centrality values. Our results highlight a role of the amygdala in neuroticism. Moreover, they indicate that a cardiac signature related to emotionality (E κ correlates with both function (increased network centrality and structure (grey matter volume of the subiculum of the hippocampal formation, suggesting a role of the hippocampal formation for

  11. The neural processing of hierarchical structure in music and speech at different timescales.

    Science.gov (United States)

    Farbood, Morwaread M; Heeger, David J; Marcus, Gary; Hasson, Uri; Lerner, Yulia

    2015-01-01

    Music, like speech, is a complex auditory signal that contains structures at multiple timescales, and as such is a potentially powerful entry point into the question of how the brain integrates complex streams of information. Using an experimental design modeled after previous studies that used scrambled versions of a spoken story (Lerner et al., 2011) and a silent movie (Hasson et al., 2008), we investigate whether listeners perceive hierarchical structure in music beyond short (~6 s) time windows and whether there is cortical overlap between music and language processing at multiple timescales. Experienced pianists were presented with an extended musical excerpt scrambled at multiple timescales-by measure, phrase, and section-while measuring brain activity with functional magnetic resonance imaging (fMRI). The reliability of evoked activity, as quantified by inter-subject correlation of the fMRI responses, was measured. We found that response reliability depended systematically on musical structure coherence, revealing a topographically organized hierarchy of processing timescales. Early auditory areas (at the bottom of the hierarchy) responded reliably in all conditions. For brain areas at the top of the hierarchy, the original (unscrambled) excerpt evoked more reliable responses than any of the scrambled excerpts, indicating that these brain areas process long-timescale musical structures, on the order of minutes. The topography of processing timescales was analogous with that reported previously for speech, but the timescale gradients for music and speech overlapped with one another only partially, suggesting that temporally analogous structures-words/measures, sentences/musical phrases, paragraph/sections-are processed separately.

  12. Neural Correlates of Emotional Personality: A Structural and Functional Magnetic Resonance Imaging Study

    Science.gov (United States)

    Koelsch, Stefan; Skouras, Stavros; Jentschke, Sebastian

    2013-01-01

    Studies addressing brain correlates of emotional personality have remained sparse, despite the involvement of emotional personality in health and well-being. This study investigates structural and functional brain correlates of psychological and physiological measures related to emotional personality. Psychological measures included neuroticism, extraversion, and agreeableness scores, as assessed using a standard personality questionnaire. As a physiological measure we used a cardiac amplitude signature, the so-called Eκ value (computed from the electrocardiogram) which has previously been related to tender emotionality. Questionnaire scores and Eκ values were related to both functional (eigenvector centrality mapping, ECM) and structural (voxel-based morphometry, VBM) neuroimaging data. Functional magnetic resonance imaging (fMRI) data were obtained from 22 individuals (12 females) while listening to music (joy, fear, or neutral music). ECM results showed that agreeableness scores correlated with centrality values in the dorsolateral prefrontal cortex, the anterior cingulate cortex, and the ventral striatum (nucleus accumbens). Individuals with higher Eκ values (indexing higher tender emotionality) showed higher centrality values in the subiculum of the right hippocampal formation. Structural MRI data from an independent sample of 59 individuals (34 females) showed that neuroticism scores correlated with volume of the left amygdaloid complex. In addition, individuals with higher Eκ showed larger gray matter volume in the same portion of the subiculum in which individuals with higher Eκ showed higher centrality values. Our results highlight a role of the amygdala in neuroticism. Moreover, they indicate that a cardiac signature related to emotionality (Eκ) correlates with both function (increased network centrality) and structure (grey matter volume) of the subiculum of the hippocampal formation, suggesting a role of the hippocampal formation for emotional

  13. Neural correlates of emotional personality: a structural and functional magnetic resonance imaging study.

    Science.gov (United States)

    Koelsch, Stefan; Skouras, Stavros; Jentschke, Sebastian

    2013-01-01

    Studies addressing brain correlates of emotional personality have remained sparse, despite the involvement of emotional personality in health and well-being. This study investigates structural and functional brain correlates of psychological and physiological measures related to emotional personality. Psychological measures included neuroticism, extraversion, and agreeableness scores, as assessed using a standard personality questionnaire. As a physiological measure we used a cardiac amplitude signature, the so-called E κ value (computed from the electrocardiogram) which has previously been related to tender emotionality. Questionnaire scores and E κ values were related to both functional (eigenvector centrality mapping, ECM) and structural (voxel-based morphometry, VBM) neuroimaging data. Functional magnetic resonance imaging (fMRI) data were obtained from 22 individuals (12 females) while listening to music (joy, fear, or neutral music). ECM results showed that agreeableness scores correlated with centrality values in the dorsolateral prefrontal cortex, the anterior cingulate cortex, and the ventral striatum (nucleus accumbens). Individuals with higher E κ values (indexing higher tender emotionality) showed higher centrality values in the subiculum of the right hippocampal formation. Structural MRI data from an independent sample of 59 individuals (34 females) showed that neuroticism scores correlated with volume of the left amygdaloid complex. In addition, individuals with higher E κ showed larger gray matter volume in the same portion of the subiculum in which individuals with higher E κ showed higher centrality values. Our results highlight a role of the amygdala in neuroticism. Moreover, they indicate that a cardiac signature related to emotionality (E κ) correlates with both function (increased network centrality) and structure (grey matter volume) of the subiculum of the hippocampal formation, suggesting a role of the hippocampal formation for

  14. A case of severe congenital kyphoscoliosis secondary to multiple bilateral thoracic pedicle aplasia

    Energy Technology Data Exchange (ETDEWEB)

    Geoffray, Anne; Leloutre, Beatrice; Albertario, Marco; Bechard-Sevette, Nancy [Fondation Lenval Children' s Hospital, Department of Pediatric Imaging, Nice (France); Clement, Jean-Luc [Fondation Lenval Children' s Hospital, Department of Orthopedic and Spine Surgery, Nice (France)

    2008-07-15

    A 9-month-old boy with congenital kyphoscoliosis secondary to multiple bilateral thoracic pedicle aplasias is presented. This anomaly has rarely been described in the literature. Plain films showed absence of thoracic pedicles bilaterally from T2 to T9, which was better demonstrated on CT multiplanar and 3-D reformatted images. There were no neurological symptoms even though the deformity progressed rapidly. Congenital kyphosis or kyphoscoliosis is often related to spinal anomalies that are located on the anterior aspect of the vertebrae. However, posterior anomalies may also be responsible and should be recognized before neurological complications occur. (orig.)

  15. Alternative of pedicle buccal fat pad for reconstruction defect in cleft palate patient

    Directory of Open Access Journals (Sweden)

    Nur Hidayat

    2016-06-01

    Full Text Available Various surgical techniques have been employed for closure of the defect in the oral cavity. The type and size of defects in the oral cavity determine the techniques to use. Pedicle Buccal Fat Pad (BFP is one alternative tissue graft for defect reconstruction in oral cavity. The objective of this paper is to determine an alternative defect reconstruction in cleft palate using pedicle BFP. In conclusion, the use of BFP for the defect reconstruction in cleft palate patients shows satisfactory results with good healing. BFP can be an alternative method in the treatment of cleft palate defect.

  16. Absent congenital cervical pedicle nearly misdiagnosed as a facet dislocation: A case report

    Directory of Open Access Journals (Sweden)

    Scott Safir

    2017-09-01

    Conclusion: In the acute trauma setting, congenital absent cervical pedicle can be difficult to differentiate from unilateral facet dislocation and may require the use of advanced imaging and close communication between the neurosurgery and radiology departments. Given the high morbidity and mortality involved in the repair of facet dislocation in a child, it is crucial to maintain high degree of clinical suspicion for absent spinal pedicle. In this case, the patient nearly underwent surgical intervention, but was ultimately able to be discharged home with no symptoms or deficits after correct diagnosis.

  17. The neural processing of hierarchical structure in music and speech at different timescales

    Directory of Open Access Journals (Sweden)

    Morwaread Mary Farbood

    2015-05-01

    Full Text Available Music, like speech, is a complex auditory signal that contains structures at multiple timescales, and as such a potentially powerful entry point into the question of how the brain integrates complex streams of information. Using an experimental design modeled after previous studies that used scrambled versions of a spoken story (Lerner, Honey, Silbert, & Hasson, 2011 and a silent movie (Hasson, Yang, Vallines, Heeger, & Rubin, 2008, we investigate whether listeners perceive hierarchical structure in music beyond short (~6 sec time windows and whether there is cortical overlap between music and language processing at multiple timescales. Experienced pianists were presented with an extended musical excerpt scrambled at multiple timescales––by measure, phrase, and section––while measuring brain activity with functional magnetic resonance imaging (fMRI. The reliability of evoked activity, as quantified by inter-subject correlation of the fMRI responses was measured. We found that response reliability depended systematically on musical structural coherence, revealing a topographically organized hierarchy of processing timescales. Early auditory areas (at the bottom of the hierarchy responded reliably in all conditions. For brain areas at the top of the hierarchy, the original (unscrambled excerpt evoked more reliable responses than any of the scrambled excerpts, indicating that these brain areas process long-timescale musical structures, on the order of minutes. The topography of processing timescales was analogous with that reported previously for speech, but the timescale gradients for music and speech overlapped with one another only partially, suggesting that temporally analogous structures––words/measures, sentences/musical phrases, paragraph/sections––are processed separately.

  18. The neural processing of hierarchical structure in music and speech at different timescales

    Science.gov (United States)

    Farbood, Morwaread M.; Heeger, David J.; Marcus, Gary; Hasson, Uri; Lerner, Yulia

    2015-01-01

    Music, like speech, is a complex auditory signal that contains structures at multiple timescales, and as such is a potentially powerful entry point into the question of how the brain integrates complex streams of information. Using an experimental design modeled after previous studies that used scrambled versions of a spoken story (Lerner et al., 2011) and a silent movie (Hasson et al., 2008), we investigate whether listeners perceive hierarchical structure in music beyond short (~6 s) time windows and whether there is cortical overlap between music and language processing at multiple timescales. Experienced pianists were presented with an extended musical excerpt scrambled at multiple timescales—by measure, phrase, and section—while measuring brain activity with functional magnetic resonance imaging (fMRI). The reliability of evoked activity, as quantified by inter-subject correlation of the fMRI responses, was measured. We found that response reliability depended systematically on musical structure coherence, revealing a topographically organized hierarchy of processing timescales. Early auditory areas (at the bottom of the hierarchy) responded reliably in all conditions. For brain areas at the top of the hierarchy, the original (unscrambled) excerpt evoked more reliable responses than any of the scrambled excerpts, indicating that these brain areas process long-timescale musical structures, on the order of minutes. The topography of processing timescales was analogous with that reported previously for speech, but the timescale gradients for music and speech overlapped with one another only partially, suggesting that temporally analogous structures—words/measures, sentences/musical phrases, paragraph/sections—are processed separately. PMID:26029037

  19. Impaired Neural Structure and Function Contributing to Autonomic Symptoms in Congenital Central Hypoventilation Syndrome

    Directory of Open Access Journals (Sweden)

    Ronald M Harper

    2015-10-01

    Full Text Available Congenital central hypoventilation syndrome (CCHS patients show major autonomic alterations in addition to their better-known breathing deficiencies. The processes underlying CCHS, mutations in the PHOX2B gene, target autonomic neuronal development, with frame shift extent contributing to symptom severity. Many autonomic characteristics, such as impaired pupillary constriction and poor temperature regulation, reflect parasympathetic alterations, and can include disturbed alimentary processes, with malabsorption and intestinal motility dyscontrol. The sympathetic nervous system changes can exert life-threatening outcomes, with dysregulation of sympathetic outflow leading to high blood pressure, time-altered and dampened heart rate and breathing responses to challenges, cardiac arrhythmia, profuse sweating, and poor fluid regulation. The central mechanisms contributing to failed autonomic processes are readily apparent from structural and functional magnetic resonance imaging studies, which reveal substantial cortical thinning, tissue injury, and disrupted functional responses in hypothalamic, hippocampal, posterior thalamic, and basal ganglia sites and their descending projections, as well as insular, cingulate, and medial frontal cortices, which influence subcortical autonomic structures. Midbrain structures are also compromised, including the raphe system and its projections to cerebellar and medullary sites, the locus coeruleus, and medullary reflex integrating sites, including the dorsal and ventrolateral medullary nuclei. The damage to rostral autonomic sites overlaps metabolic, affective and cognitive regulatory regions, leading to hormonal disruption, anxiety, depression, behavioral control, and sudden death concerns. The injuries suggest that interventions for mitigating hypoxic exposure and nutrient loss may provide cellular protection, in the same fashion as interventions in other conditions with similar malabsorption, fluid turnover

  20. Neural responses to nostalgia-evoking music modeled by elements of dynamic musical structure and individual differences in affective traits.

    Science.gov (United States)

    Barrett, Frederick S; Janata, Petr

    2016-10-01

    Nostalgia is an emotion that is most commonly associated with personally and socially relevant memories. It is primarily positive in valence and is readily evoked by music. It is also an idiosyncratic experience that varies between individuals based on affective traits. We identified frontal, limbic, paralimbic, and midbrain brain regions in which the strength of the relationship between ratings of nostalgia evoked by music and blood-oxygen-level-dependent (BOLD) signal was predicted by affective personality measures (nostalgia proneness and the sadness scale of the Affective Neuroscience Personality Scales) that are known to modulate the strength of nostalgic experiences. We also identified brain areas including the inferior frontal gyrus, substantia nigra, cerebellum, and insula in which time-varying BOLD activity correlated more strongly with the time-varying tonal structure of nostalgia-evoking music than with music that evoked no or little nostalgia. These findings illustrate one way in which the reward and emotion regulation networks of the brain are recruited during the experiencing of complex emotional experiences triggered by music. These findings also highlight the importance of considering individual differences when examining the neural responses to strong and idiosyncratic emotional experiences. Finally, these findings provide a further demonstration of the use of time-varying stimulus-specific information in the investigation of music-evoked experiences. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Neural structure and social dysfunction in individuals at clinical high risk for psychosis.

    Science.gov (United States)

    Lincoln, Sarah Hope; Hooker, Christine I'Lee

    2014-12-30

    Individuals at a clinical high risk (CHR) for psychosis have gray matter volume (GMV) abnormalities that are similar to, though less severe than, those in individuals with schizophrenia. Less GMV in schizophrenia is related to worse social cognition and social functioning, but the relationship between GMV and social functioning in CHR individuals has yet to be investigated. The aim of this study was to (1) investigate differences in GMV between healthy controls (HC) and CHR individuals, and (2) evaluate the relationship between GMV and social functioning in these two groups. Participants comprised 22 CHR and 21 HC individuals who completed a structural magnetic resonance imaging (MRI) scan as well as self-reported and interviewer-rated measures of social functioning. Processing and analysis of structural images were completed using voxel based morphometry (VBM). Results showed that the CHR group had less GMV in the left postcentral gyrus, bilateral parahippocampual gyri, and left anterior cingulate cortex. Reduced GMV in the postcentral gyrus and the anterior cingulate was related to self-reported social impairment across the whole group. This study has implications for the neurobiological basis of social dysfunction present before the onset of psychosis. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  2. Tinnitus Neural Mechanisms and Structural Changes in the Brain: The Contribution of Neuroimaging Research

    Directory of Open Access Journals (Sweden)

    Simonetti, Patricia

    2015-03-01

    Full Text Available Introduction Tinnitus is an abnormal perception of sound in the absence of an external stimulus. Chronic tinnitus usually has a high impact in many aspects of patients' lives, such as emotional stress, sleep disturbance, concentration difficulties, and so on. These strong reactions are usually attributed to central nervous system involvement. Neuroimaging has revealed the implication of brain structures in the auditory system. Objective This systematic review points out neuroimaging studies that contribute to identifying the structures involved in the pathophysiological mechanism of generation and persistence of various forms of tinnitus. Data Synthesis Functional imaging research reveals that tinnitus perception is associated with the involvement of the nonauditory brain areas, including the front parietal area; the limbic system, which consists of the anterior cingulate cortex, anterior insula, and amygdala; and the hippocampal and parahippocampal area. Conclusion The neuroimaging research confirms the involvement of the mechanisms of memory and cognition in the persistence of perception, anxiety, distress, and suffering associated with tinnitus.

  3. Common neural structures activated by epidural and transcutaneous lumbar spinal cord stimulation: Elicitation of posterior root-muscle reflexes.

    Science.gov (United States)

    Hofstoetter, Ursula S; Freundl, Brigitta; Binder, Heinrich; Minassian, Karen

    2018-01-01

    Epidural electrical stimulation of the lumbar spinal cord is currently regaining momentum as a neuromodulation intervention in spinal cord injury (SCI) to modify dysregulated sensorimotor functions and augment residual motor capacity. There is ample evidence that it engages spinal circuits through the electrical stimulation of large-to-medium diameter afferent fibers within lumbar and upper sacral posterior roots. Recent pilot studies suggested that the surface electrode-based method of transcutaneous spinal cord stimulation (SCS) may produce similar neuromodulatory effects as caused by epidural SCS. Neurophysiological and computer modeling studies proposed that this noninvasive technique stimulates posterior-root fibers as well, likely activating similar input structures to the spinal cord as epidural stimulation. Here, we add a yet missing piece of evidence substantiating this assumption. We conducted in-depth analyses and direct comparisons of the electromyographic (EMG) characteristics of short-latency responses in multiple leg muscles to both stimulation techniques derived from ten individuals with SCI each. Post-activation depression of responses evoked by paired pulses applied either epidurally or transcutaneously confirmed the reflex nature of the responses. The muscle responses to both techniques had the same latencies, EMG peak-to-peak amplitudes, and waveforms, except for smaller responses with shorter onset latencies in the triceps surae muscle group and shorter offsets of the responses in the biceps femoris muscle during epidural stimulation. Responses obtained in three subjects tested with both methods at different time points had near-identical waveforms per muscle group as well as same onset latencies. The present results strongly corroborate the activation of common neural input structures to the lumbar spinal cord-predominantly primary afferent fibers within multiple posterior roots-by both techniques and add to unraveling the basic mechanisms

  4. Modified feed-forward neural network structures and combined-function-derivative approximations incorporating exchange symmetry for potential energy surface fitting.

    Science.gov (United States)

    Nguyen, Hieu T T; Le, Hung M

    2012-05-10

    The classical interchange (permutation) of atoms of similar identity does not have an effect on the overall potential energy. In this study, we present feed-forward neural network structures that provide permutation symmetry to the potential energy surfaces of molecules. The new feed-forward neural network structures are employed to fit the potential energy surfaces for two illustrative molecules, which are H(2)O and ClOOCl. Modifications are made to describe the symmetric interchange (permutation) of atoms of similar identity (or mathematically, the permutation of symmetric input parameters). The combined-function-derivative approximation algorithm (J. Chem. Phys. 2009, 130, 134101) is also implemented to fit the neural-network potential energy surfaces accurately. The combination of our symmetric neural networks and the function-derivative fitting effectively produces PES fits using fewer numbers of training data points. For H(2)O, only 282 configurations are employed as the training set; the testing root-mean-squared and mean-absolute energy errors are respectively reported as 0.0103 eV (0.236 kcal/mol) and 0.0078 eV (0.179 kcal/mol). In the ClOOCl case, 1693 configurations are required to construct the training set; the root-mean-squared and mean-absolute energy errors for the ClOOCl testing set are 0.0409 eV (0.943 kcal/mol) and 0.0269 eV (0.620 kcal/mol), respectively. Overall, we find good agreements between ab initio and NN prediction in term of energy and gradient errors, and conclude that the new feed-forward neural-network models advantageously describe the molecules with excellent accuracy.

  5. Error and attack tolerance of synchronization in Hindmarsh–Rose neural networks with community structure

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chun-Hsien, E-mail: chli@nknucc.nknu.edu.tw [Department of Mathematics, National Kaohsiung Normal University, Yanchao District, Kaohsiung City 82444, Taiwan (China); Yang, Suh-Yuh, E-mail: syyang@math.ncu.edu.tw [Department of Mathematics, National Central University, Jhongli City, Taoyuan County 32001, Taiwan (China)

    2014-03-01

    Synchronization is one of the most important features observed in large-scale complex networks of interacting dynamical systems. As is well known, there is a close relation between the network topology and the network synchronizability. Using the coupled Hindmarsh–Rose neurons with community structure as a model network, in this paper we explore how failures of the nodes due to random errors or intentional attacks affect the synchronizability of community networks. The intentional attacks are realized by removing a fraction of the nodes with high values in some centrality measure such as the centralities of degree, eigenvector, betweenness and closeness. According to the master stability function method, we employ the algebraic connectivity of the considered community network as an indicator to examine the network synchronizability. Numerical evidences show that the node failure strategy based on the betweenness centrality has the most influence on the synchronizability of community networks. With this node failure strategy for a given network with a fixed number of communities, we find that the larger the degree of communities, the worse the network synchronizability; however, for a given network with a fixed degree of communities, we observe that the more the number of communities, the better the network synchronizability.

  6. Error and attack tolerance of synchronization in Hindmarsh-Rose neural networks with community structure

    Science.gov (United States)

    Li, Chun-Hsien; Yang, Suh-Yuh

    2014-03-01

    Synchronization is one of the most important features observed in large-scale complex networks of interacting dynamical systems. As is well known, there is a close relation between the network topology and the network synchronizability. Using the coupled Hindmarsh-Rose neurons with community structure as a model network, in this paper we explore how failures of the nodes due to random errors or intentional attacks affect the synchronizability of community networks. The intentional attacks are realized by removing a fraction of the nodes with high values in some centrality measure such as the centralities of degree, eigenvector, betweenness and closeness. According to the master stability function method, we employ the algebraic connectivity of the considered community network as an indicator to examine the network synchronizability. Numerical evidences show that the node failure strategy based on the betweenness centrality has the most influence on the synchronizability of community networks. With this node failure strategy for a given network with a fixed number of communities, we find that the larger the degree of communities, the worse the network synchronizability; however, for a given network with a fixed degree of communities, we observe that the more the number of communities, the better the network synchronizability.

  7. Reliability of Triggered EMG for Prediction of Safety during Pedicle Screw Placement in Adolescent Idiopathic Scoliosis Surgery

    Science.gov (United States)

    Lee, Hyun-Joo; Jeong, Won-Ju; Oh, Chang-Wug; Bae, Jae-Sung; Cho, Hwan-Seong; Jeon, In-Ho; Cho, Chang-Hyun; Park, Byung-Chul

    2011-01-01

    Study Design We performed a prospective study to evaluate the reliability of using triggered electromyography (EMG) for predicting pedicle wall breakthrough during the placement of pedicle screw in adolescent idiopathic scoliosis surgery. Purpose We wanted to correlate pedicle wall breakthrough with the triggered EMG threshold of stimulation and the postoperative computed tomography (CT) findings. Overview of Literature Pedicle wall breakthrough has been reported to be difficult to evaluate by radiographs. Triggered EMG had been found to be a more sensitive test to detect this breakthrough. Methods Seven patients who underwent the insertion of 103 pedicle screws were evaluated. The triggered EMG activity was recorded from several muscles depending on the level of screw placement. The postoperative CT scans were read by a spine surgeon who was a senior fellow in orthopedics, and a musculoskeletal radiologist. Results The mean age at surgery was 12.6 years (range, 11 to 17 years). The preoperative mean Cobb angle was 54.7° (range, 45 to 65°). There were 80 thoracic screws and 23 lumbar screws. All the screws had stimulation thresholds of ≥ 6 mA, except 3 screws with the stimulation threshold of EMG helps to assess the pedicle screw placement. Pedicle screws that had stimulation threshold of ≥ 6 mA were safe, with 90.3% reliability, as was assessed on the postoperative CT scans. PMID:21386946

  8. Pull out strength calculator for pedicle screws using a surrogate ensemble approach.

    Science.gov (United States)

    Varghese, Vicky; Ramu, Palaniappan; Krishnan, Venkatesh; Saravana Kumar, Gurunathan

    2016-12-01

    Pedicle screw instrumentation is widely used in the treatment of spinal disorders and deformities. Currently, the surgeon decides the holding power of instrumentation based on the perioperative feeling which is subjective in nature. The objective of the paper is to develop a surrogate model which will predict the pullout strength of pedicle screw based on density, insertion angle, insertion depth and reinsertion. A Taguchi's orthogonal array was used to design an experiment to find the factors effecting pullout strength of pedicle screw. The pullout studies were carried using polyaxial pedicle screw on rigid polyurethane foam block according to American society for testing of materials (ASTM F543). Analysis of variance (ANOVA) and Tukey's honestly significant difference multiple comparison tests were done to find factor effect. Based on the experimental results, surrogate models based on Krigging, polynomial response surface and radial basis function were developed for predicting the pullout strength for different combination of factors. An ensemble of these surrogates based on weighted average surrogate model was also evaluated for prediction. Density, insertion depth, insertion angle and reinsertion have a significant effect (p experimental values and surrogate models. This can be used in pre-surgical planning and decision support system for spine surgeon. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  9. Utility of Glissonean Pedicle Transection for Surgical Treatment of Severe Liver Trauma

    Directory of Open Access Journals (Sweden)

    Satoshi Koizumi

    2017-04-01

    Full Text Available The most common initial strategy for treatment of severe liver trauma is damage control in which hemostasis is achieved by perihepatic gauze packing and/or vascular embolization. However, we encounter patients in whom this strategy alone is not adequate. We have applied the principles of Glissonean pedicle transection, a technique that was originally devised to ensure safe and quick performance of planned hepatectomy for liver cancer, to 3 cases of severe liver trauma. We performed Glissonean pedicle ligation during damage control surgery in 2 patients and Glissonean pedicle transection during the definitive surgery in 1 patient. We describe the approaches and our experience with them, including operation times and outcomes. From our experience thus far, it seems that 8–12 h after the damage control procedure is appropriate for performing the definitive surgery. Although there are some problems posed by this strategy and cases to which it will not be applicable, the method seems to be particularly useful for cases of severe liver trauma in which the damage is extensive and involves the Glissonean pedicles near the hepatic hilus. We describe our 3 cases in detail and review our experience in light of the available literature.

  10. Congenital absence of a cervical pedicle: report of two cases and review of the literature.

    Science.gov (United States)

    Sheehan, J; Kaptain, G; Sheehan, J; Jane, J

    2000-12-01

    The congenital absence of a cervical pedicle is a rare clinical entity. Patients with this anomaly tend to present with cervical pain or after a traumatic incident. Initial evaluations with conventional radiography frequently lead to misinterpretation and misguided intervention. We report two cases of absent cervical pedicles and describe the presentation, diagnosis, and treatment of these patients. Moreover, we review the literature on this clinical entity. The first patient was a 4-year-old boy who presented with neck pain after falling off a trampoline. His neurological examination did not reveal any focal abnormalities, but radiographs were thought to be consistent with a right, C4-C5, unilateral, jumped facet. The second patient was a 27-year-old woman who presented with severe neck, back, and left upper extremity pain and paresthesias after an alleged incident of spousal abuse. Her neurological examination results were remarkable for left upper extremity weakness and hemibody sensory changes. Conventional radiographs were thought to reveal a left, C3-C4, unilateral, locked facet. For both patients, reduction attempts were made with Gardner-Wells tongs and traction. After failure to achieve adequate reduction, evaluations using two-dimensional computed tomography confirmed congenitally absent cervical pedicles. Both patients were ultimately treated conservatively and experienced resolution of their presenting symptoms. The congenital absence of a cervical pedicle is a rare entity that is frequently misdiagnosed. Diagnoses can be accurately confirmed with two-dimensional computed tomography. Conservative treatment resulted in successful management of this clinical entity.

  11. Multiple pedicled flaps cover for large defects following resection of malignant tumors with partition concept.

    Science.gov (United States)

    Ji, Chenyang; Li, Ruiting; Shen, Grace; Zhang, Jinming; Liang, Weiqiang

    2017-07-01

    Large defects after skin malignant tumors resection were difficult to repair. We introduced a partition concept, in which the large defects were divided into several subunits, and each subunit was repaired by a certain pedicled flap to achieve a complete coverage.Between May 2012 and Oct 2016, 8 patients with skin malignant tumors underwent radical resection. Prior to surgery, the dimension of the potential defect after tumor ablation was estimated and outlined. After evaluation, the partition concept was applied and the defects were divided into several subunits. Also, the rationality of the choice of pedicled flap was evaluated. Each flap was used to cover its specific subunits defect.After excision, the defect areas were from 13 × 17 cm to 36 × 23 cm. Each subunit was designed to be repaired with a pedicled flap, which included local random flap, superficial iliac artery flap, transverse rectus abdominis myocutaneous (TRAM) flap, lateral thoracic advanced island flap, anterolateral thigh (ALT) flap, anteromedial thigh (AMT) flap, and deep circumflex iliac artery (DCIA) flap. Primary closure of both donor and recipient sites was achieved in all patients. All the flaps survived. Flap necrosis was not observed.Reconstruction of large defects following resection of malignant tumors with multiple pedicled flaps was a reliable method. The partition concept is useful in the reconstruction of large tumor wounds in 1-stage operation.

  12. Navigated pedicle screw placement using computed tomographic data in dorsolumbar fractures

    Directory of Open Access Journals (Sweden)

    Saurabh Kapoor

    2014-01-01

    Conclusion: CT-based navigation is effective in improving accuracy of pedicle screw placement in traumatic injuries of dorsolumbar spine (T9-L5, however additional cost of procuring CT scan to the patient and cost of equipment is of significant concern in developing countries. Reduced radiation exposure and lowered ergonomic constraints around the operation table are its additional benefits.

  13. How safe is minimally invasive pedicle screw placement for treatment of thoracolumbar spine fractures?

    Science.gov (United States)

    Heintel, Timo Michael; Dannigkeit, Stefan; Fenwick, Annabel; Jordan, Martin Cornelius; Jansen, Hendrik; Gilbert, Fabian; Meffert, Rainer

    2017-05-01

    Prospective analysis of patients who underwent minimally invasive posterior instrumentation. The purpose of this study was to evaluate the safety of minimally invasive pedicle screw placement in patients with unstable thoracic and lumbar spine fractures using the conventional fluoroscopy technique. Although wound infection, haematoma, and new neurological deficit due to screw malplacement remain a common source of morbidity, estimates of their rates of occurrence remain relatively limited. 2052 percutaneous pedicle screws in 433 consecutive patients were evaluated. The accuracy of pedicle screw placement was based on evaluation of axial 3-mm slice computed tomography scans. Morbidity and mortality data were collected prospectively. A total of 2029 of 2052 screws (99%) had a good or excellent position. 5 screws (0.2%) showed a higher grade violation of the medial pedicle wall. Seven patients (1.8%) needed revision due to screw malposition (3 pat.), surgical site infection, postoperative haematoma, implant failure (2 pat.), and technical difficulties. Minimally invasive transpedicular instrumentation is an accurate, reliable, and safe procedure to treat thoracic and lumbar spine fractures.

  14. Minimally invasive mini open split-muscular percutaneous pedicle screw fixation of the thoracolumbar spine

    Directory of Open Access Journals (Sweden)

    Murat Ulutaş

    2015-03-01

    Full Text Available We prospectively assessed the feasibility and safety of a new percutaneous pedicle screw (PPS fixation technique for instrumentation of the thoracic and lumbar spine in this study. All patients were operated in the prone position under general anesthesia. A 6 to 8 cm midline skin incision was made and wide sub-cutaneous dissection was performed. The paravertebral muscles were first dissected subperiosteally into the midline incision of the fascia for lumbar microdiscectomy with transforaminal lumbar interbody fusion cage implantation. After the secondary paramedian incisions on the fascia, the PPSs were inserted via cleavage of the multifidus muscles directly into the pedicles under fluoroscopy visualization. A total of 35 patients underwent surgery with this new surgical technique. The control group for operative time, blood loss and analgesic usage consisted of 35 randomly selected cases from our department. The control group underwent surgery via conventional pedicle screw instrumentation with paramedian fusion. All patients in the minimal invasive surgery series were ambulatory with minimal pain on the first postoperative day. The operation time and blood loss and the postoperative analgesic consumption were significantly less with this new technique. In conclusion, the minimal invasive mini open split-muscular percutaneous pedicle screw fixation technique is safe and feasible. It can be performed via a short midline skin incision and can also be combined with interbody fusion, causing minimal pain without severe muscle damage.

  15. Clinical evaluation of patients undergoing dynamic pedicle fixation in lumbar spine

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    Felipe José Vieira Figueiredo

    2015-06-01

    Full Text Available OBJECTIVE: To evaluate the preliminary clinical results and complications in patients undergoing dynamic pedicle fixation of the spine in the treatment of a specific group of degenerative lumbar disease.METHODS: In this preliminary retrospective study, we selected 14 patients who underwent surgery from January 2006 to July 2010. We selected only patients with spondylolisthesis without spondylolysis (Grade 1 Meyerding. All patients underwent surgery at one level and the levels mostly addressed were: L3-L4, L4-L5 or L5-S1. The approach was the same in all patients (posterior median approach with preservation of the posterior elements. All patients underwent intense conservative treatment without clinical response and the same research algorithm preoperatively.RESULTS: Retrospective analysis of Oswestry questionnaire after selection and publication of results of 14 patients with Grade 1 spondylolisthesis who underwent dynamic pedicle stabilization in a total of 56 pedicle screws, being all in one level. There was no fracture of any screws, the mean hospital stay was a day and a half, no patient required blood transfusion and there were no cases of infection, with significant improvement in the Oswestry questionnaire.CONCLUSION: In this study, the dynamic pedicle stabilization method proved to be an excellent treatment option when surgical criteria are strictly adhered to. There was an improvement in Oswestry values, lower hospital stay and low rate of complications, consisting of an alternative in motion preservation surgery.

  16. Minimizing Pedicle Screw Pullout Risks: A Detailed Biomechanical Analysis of Screw Design and Placement.

    Science.gov (United States)

    Bianco, Rohan-Jean; Arnoux, Pierre-Jean; Wagnac, Eric; Mac-Thiong, Jean-Marc; Aubin, Carl-Éric

    2017-04-01

    Detailed biomechanical analysis of the anchorage performance provided by different pedicle screw designs and placement strategies under pullout loading. To biomechanically characterize the specific effects of surgeon-specific pedicle screw design parameters on anchorage performance using a finite element model. Pedicle screw fixation is commonly used in the treatment of spinal pathologies. However, there is little consensus on the selection of an optimal screw type, size, and insertion trajectory depending on vertebra dimension and shape. Different screw diameters and lengths, threads, and insertion trajectories were computationally tested using a design of experiment approach. A detailed finite element model of an L3 vertebra was created including elastoplastic bone properties and contact interactions with the screws. Loads and boundary conditions were applied to the screws to simulate axial pullout tests. Force-displacement responses and internal stresses were analyzed to determine the specific effects of each parameter. The design of experiment analysis revealed significant effects (Pdesign characteristics and surgical choices, enabling to recommend strategies to improve single pedicle screw performance under axial loading.

  17. Closure of oro-antral fistula with pedicled buccal fat pad. A case ...

    African Journals Online (AJOL)

    This article demonstrates the use of BFP in the repair of chronic oro-antral fistula. Methods: A case of a chronic oro-antral fistula of 5- year duration in a 56- year old man successfully repaired with pedicled buccal fat pad after unsuccessful several attempts with other local flaps is presented. A review of relevant literature ...

  18. Conserved structural domains in FoxD4L1, a neural forkhead box transcription factor, are required to repress or activate target genes.

    Directory of Open Access Journals (Sweden)

    Steven L Klein

    Full Text Available FoxD4L1 is a forkhead transcription factor that expands the neural ectoderm by down-regulating genes that promote the onset of neural differentiation and up-regulating genes that maintain proliferative neural precursors in an immature state. We previously demonstrated that binding of Grg4 to an Eh-1 motif enhances the ability of FoxD4L1 to down-regulate target neural genes but does not account for all of its repressive activity. Herein we analyzed the protein sequence for additional interaction motifs and secondary structure. Eight conserved motifs were identified in the C-terminal region of fish and frog proteins. Extending the analysis to mammals identified a high scoring motif downstream of the Eh-1 domain that contains a tryptophan residue implicated in protein-protein interactions. In addition, secondary structure prediction programs predicted an α-helical structure overlapping with amphibian-specific Motif 6 in Xenopus, and similarly located α-helical structures in other vertebrate FoxD proteins. We tested functionality of this site by inducing a glutamine-to-proline substitution expected to break the predicted α-helical structure; this significantly reduced FoxD4L1's ability to repress zic3 and irx1. Because this mutation does not interfere with Grg4 binding, these results demonstrate that at least two regions, the Eh-1 motif and a more C-terminal predicted α-helical/Motif 6 site, additively contribute to repression. In the N-terminal region we previously identified a 14 amino acid motif that is required for the up-regulation of target genes. Secondary structure prediction programs predicted a short β-strand separating two acidic domains. Mutant constructs show that the β-strand itself is not required for transcriptional activation. Instead, activation depends upon a glycine residue that is predicted to provide sufficient flexibility to bring the two acidic domains into close proximity. These results identify conserved predicted

  19. A study on a pedicle-screw-based reduction method for artificially reduced artifacts

    Science.gov (United States)

    Kim, Hyun-Ju; Lee, Hae-Kag; Cho, Jae-Hwan

    2017-09-01

    The purpose of this study is a quantitative analysis of the degree of the reduction of the artifacts that are induced by pedicle screws through the application of the recently developed iterative metallic artifact reduction (I MAR) software. Screw-type implants that are composed of 4.5 g/cm3 titanium (Ti) with an approximate average computed tomography (CT) value of 6500 Hounsfield units (HUs) that are used for the treatment of spinal diseases were placed in paraffin, a tissueequivalent material, and then dried. After the insertion, the scanning conditions were fixed as 120 kVp and 250 mA using multidetector computed tomography (MDCT) (Enlarge, Siemens, Germany). The slice thickness and the increment were set at the fields of view (FOVs) of 3 mm and 120 mm, respectively; the pitch is 0.8; the rotation time is 1 s; and the I MAR software was applied to the raw data of the acquired images to compare the CT-value changes of the posterior images. When the I MAR software was applied to animal vertebrae, it was possible to reduce the 65.7% image loss of the black-hole-effect image through the application of the I MAR software. When the I MAR image loss (%) was compared with the white-streak-effect image, the high-intensity image type with the white-streak effect could be reduced by 91.34% through the application of the I MAR software. In conclusion, a metal artifact that is due to a high-density material can be reduced more effectively when the I MAR algorithm is applied compared with that from the application of the conventional MAR algorithm. The I MAR can provide information on the various tissues that form around the artifact and the reduced metal structures, which can be helpful for radiologists and clinicians in their determination of an accurate diagnosis.

  20. Does a skeletonized internal thoracic artery give fewer postoperative complications than a pedicled artery for patients undergoing coronary artery bypass grafting?

    Science.gov (United States)

    Fouquet, Olivier; Tariel, François; Desulauze, Pierre; Mével, Gwenaël

    2015-05-01

    A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'Does a skeletonized internal thoracic artery (ITA) give fewer postoperative complications than a pedicled artery for patients undergoing coronary artery bypass grafting?' Altogether, 98 papers were found using the reported search, of which 11 represented the best evidence to answer the clinical question. Papers about patency of skeletonized versus pedicled internal thoracic artery were excluded. The analysed complications were essentially mediastinitis, superficial sternal infection, wound infection, chest pain and pulmonary function. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Grafts used were either single ITA (LITA or RITA, left or right, respectively) or bilateral ITAs (BITAs). One prospective randomized controlled trial was identified, which found that benefits of skeletonized harvesting included increased graft length, increased graft flow and decreased incidence of mediastinitis. All of the six studies concerning wound infection demonstrate fewer complications when ITA is skeletonized. One of the three papers describing postoperative mortality demonstrated lower 30-day mortality, but there was no long-term analysis. Three studies describing postoperative chest pain reported a lower score on the visual analogue scale (VAS) within 30 days. One of them indicates that the pedicled group has a significantly greater VAS, pain disability index and short-form McGill Pain questionnaire score at 1 and 3 months. The hospital stay was shorter for three studies conducted on this subject. One study about pulmonary function reported a better ratio of pre- versus postoperative values of forced vital capacity. Despite longer operating times, skeletonization leads to fewer wound infections, reduced chest pain, allows a shorter hospital stay and better

  1. Placement of C1 Pedicle Screws Using Minimal Exposure: Radiographic, Clinical, and Literature Validation.

    Science.gov (United States)

    Menger, Richard P; Storey, Christopher M; Nixon, Menarvia K C; Haydel, Justin; Nanda, Anil; Sin, Anthony

    2015-01-01

    Traditional C1-2 fixation involves placement of C1 lateral mass screws. Evolving techniques have led to the placement of C1 pedicle screws to avoid exposure of the C1-C2 joint capsule. Our minimal dissection technique utilizes anatomical landmarks with isolated exposure of C2 and the inferior posterior arch of C1. We evaluate this procedure clinically and radiographically through a technical report. Consecutive cases of cranial-vertebral junction surgery were reviewed for one fellowship trained spinal surgeon from 2008-2014. Information regarding sex, age, indication for surgery, private or public hospital, intra-operative complications, post-operative neurological deterioration, death, and failure of fusion was extracted. Measurement of pre-operative axial and sagittal CT scans were performed for C1 pedicle width and C1 posterior arch height respectively. 64 patients underwent posterior cranio-vertebral junction fixation surgery. 40 of these patients underwent occipital-cervical fusion procedures. 7/9 (77.8%) C1 instrumentation cases were from trauma with the remaining two (22.2%) from oncologic lesions. The average blood loss among isolated C1-C2 fixation was 160cc. 1/9 patients (11.1%) suffered pedicle breech requiring sub-laminar wiring at the C1 level. On radiographic measurement, the average height of the C1 posterior arch was noted at 4.3mm (range 3.8mm to 5.7mm). The average width of the C1 pedicle measured at 5.3mm (range 2.8 to 8.7mm). The patient with C1 pedicle screw failure had a pedicle width of 2.78mm on pre-operative axial CT imaging. Our study directly adds to the literature with level four evidence supporting a minimal dissection of C1 arch in the placement of C1 pedicle screws with both radiographic and clinical validation. Justification of this technique avoids C2 nerve root manipulation or sacrifice, reduces bleeding associated with the venous plexus, and leaves the third segment of the vertebral artery unexplored. Pre-operative review of

  2. Freehand technique for C2 pedicle and pars screw placement: safe or not?

    Science.gov (United States)

    Punyarat, Prachya; Riew, K Daniel; Klawson, Benjamin T; Peters, Colleen; Lertudomphonwanit, Thamrong; Buchowski, Jacob M

    2017-11-16

    During placement of C2 pedicle and pars screws, intraoperative fluoroscopy is used so that neurovascular complications can be avoided, and screws can be placed in the proper position. However, this method is time consuming and increases radiation exposure. Furthermore, it does not guarantee completely safe and accurate screw placement. To evaluate the safety of the C2 pedicle and pars screw placement without fluoroscopic or other guidance methods. Retrospective comparative study. One hundred and ninety-eight patients who underwent placement of C2 pedicle or pars screws without any intraoperative radiographic guidance were included. Medical records and postoperative CT scans were evaluated. Clinical data were reviewed for intraoperative and postoperative complications. Accuracy of screw placement was evaluated with post-op CT scans using a previously published cortical-breach grading system (described by location and percentage of screw diameter over cortical edge (0 = none; grade I = pars screws were inserted by two experienced surgeons. There were no cases of CSF leakage and no neurovascular complications during screw placement. Postoperative CT scans were available for 76 patients, which included 52 pedicle and 87 pars screws. For cases with C2 pedicle screws, there were 12 breaches (23%); these included 10 screws with a grade I breach (19%), 1 screw with a grade II breach (2%), and 1 screw with a grade IV breach (2%). Lateral breaches occurred in 7 screws (13%), inferior breaches in 3 (6%), and superior breaches in 2 (4%). For cases with C2 pars screws, there were 10 breaches (11%); these included 6 screws with a grade I breach (7%), 2 screws with a grade II breach (2%), and 2 screws with a grade IV breach (2%). Medial breaches were found in 4 (5%), lateral breaches in 2 (2%), inferior breaches in 2 (2%), and superior breaches in 2 (2%). 2 of the cases with superior breaches (1 for pedicle and 1 for pars) experienced occipital neuralgia months after surgery

  3. Safety and esthetic outcomes of therapeutic mammoplasty using medial pedicle for early breast cancer

    Directory of Open Access Journals (Sweden)

    Roshdy S

    2015-07-01

    Full Text Available Sameh Roshdy,1 Osama Hussein,1 Ashraf Khater,1 Mohammad Zuhdy,1 Hend A El-Hadaad,2 Omar Farouk,1 Ahmad Senbel,1 Adel Fathi,1 Emadeldeen Hamed,1 Adel Denewer1 1Department of Surgical Oncology, Mansoura Oncology Center, 2Department of Clinical Oncology and Nuclear Medicine, Faculty of Medicine, Mansoura University, Mansoura, Egypt Background: Although therapeutic mammoplasty (TM was introduced for treatment of localized ductal carcinoma in situ and invasive breast carcinoma (stages I and II in females with large breast size, the suitability of medial pedicle TM for treatment of breast tumors at different locations has not been established. The objective of this study was to assess the safety and esthetic outcome of medial pedicle TM for breast tumors at different locations. Methods: The study was conducted from February 2012 to July 2014. Consecutive patients with early breast carcinoma with medium- and large-sized breasts, with or without ptosis, who were offered medial pedicle TM were included in the study. Patients who were not candidates for breast-conserving surgery or those with tumors located along the medial pedicle were excluded. All patients received immediate postoperative adjuvant chemoradiotherapy. Results: Thirty patients with a mean age of 48.5 years received medial pedicle TM in the breast harboring the tumor or, additionally, the other breast (N=14. The tumors were in the upper (60.0%, lower (26.7%, and lateral (13.3% quadrants. Minor complications occurred in five cases (5/30, 16.7% in the ipsilateral and in two (2/14, 14.3% contralateral breasts. No wound dehiscence or areolar necrosis was recorded. A total of 22 (73.3% patients were scored as excellent cosmesis. After a median follow-up of 20 months, no locoregional recurrence or distant metastases were observed. Conclusion: TM using a medial pedicle is a safe and appealing technique among women with tumors at different locations. Keywords: therapeutic mammoplasty, medial

  4. Perforator pedicled propeller flaps for soft tissue coverage of lower leg and foot defects.

    Science.gov (United States)

    Dong, Kai-xuan; Xu, Yong-qing; Fan, Xin-yu; Xu, Long-jiang; Su, Xi-xiong; Long, Hai; Xu, Li-qi; He, Xiao-qing

    2014-02-01

    To investigate the efficiency of perforator pedicled propeller flaps for soft tissue coverage of lower leg and foot defects. Twenty patients (12 male, 8 females; mean age 28 years, range, 5-75) with soft tissue defects of the lower leg and foot were retrospectively reviewed. Their defects had been repaired with perforator pedicled propeller flaps from September 2011 to October 2013 and included five cases of injuries caused by spokes, four of infection with postoperative skin necrosis, two of dorsal skin defects caused by heavy objects and nine caused by car accidents. The areas of soft tissue defect were from 2 cm × 8 cm to 10 cm × 20 cm. Fifteen cases had terminal branch of the peroneal artery perforator flaps and five posterior tibia artery perforator flaps, flap size ranging from 5 cm × 11 cm to 12 cm × 28 cm. Color Doppler ultrasound was used to locate all perforator vessels, the calibers of which ranged from 0.8 mm to 1.0 mm. The intraoperative coincidence rate of the color Doppler ultrasound was 96.7%. The donor sites were sutured directly in 12 cases and skin grafted in 8. One case had a venous crisis within 24 h that was treated by removal some sutures and drainage. All cases were followed up for 1-18 months; all flaps survived well and pedicles had a satisfactory appearance. The patients were extremely satisfied with the results for repair. Perforator pedicled propeller flaps have the advantages over other pedicle flap of being simple, safe, and effective and not involving vascular anastomosis. © 2014 Chinese Orthopaedic Association and Wiley Publishing Asia Pty Ltd.

  5. Role of dissection of secondary branches of splenic pedicle in portal hypertension cases undergoing splenectomy.

    Science.gov (United States)

    Liu, Ying-bin; Kong, Ying; Wang, Xu-an; Wang, Jian-wei; Li, Jiang-tao; Wang, Yong; Chen, Yan; Chen, De-qing; Weng, Wei-hong; Zhang, Zhi-ping; Wu, Xiang-song; Fei, Xiao-zhou; Quan, Zhi-wei; Li, Song-gang; Li, Ji-yu; Cao, Li-ping; Peng, Shu-you

    2008-11-20

    It is well known that conventional splenectomy, which requires careful handling and ligation of tissue of the splenic hilum, can easily cause complications such as splenic fever and pancreatic fistula. Here, we use the technique of dissection of the secondary branches of the splenic pedicle to handle the hilum in the portal hypertension patients who are subjected to splenectomy. We retrospectively compared and analyzed the complications, postoperative hospital stay, operative time, and occurrence of hemorrhage in 121 patients with portal hypertension undergoing splenectomy and devascularization of the gastric cardia from January 1999 to December 2007. The selected cases consisted of 51 patients undergoing conventional splenectomy and 70 patients undergoing dissection of secondary branches of the splenic pedicle. In addition, we analyzed the relationship between size of the spleen and occurrence of complications. The incidence of pancreatic fistula and splenic fever (0/70 and 9/70) was lower in patients undergoing dissection of secondary branches of the splenic pedicle as compared with that of the conventional group (5/51 and 18/51 respectively). In addition, there was no significant difference in operative time and volume of blood loss between two groups. The spleen thickness of those patients who had pancreatic fistula and splenic fever was significantly greater than those without complications. These results indicate that dissection of secondary branches of the splenic pedicle in portal hypertension patients undergoing splenectomy can decrease the incidence of splenic fever and pancreatic fistula, and shorten the postoperative hospital stay, especially in the patients with a large spleen. So dissection of secondary branches of the splenic pedicle is a valuable technique for splenectomy.

  6. Comparison of surgical treatment in Lenke 5C adolescent idiopathic scoliosis: anterior dual rod versus posterior pedicle fixation surgery: a comparison of two practices.

    Science.gov (United States)

    Geck, Matthew J; Rinella, Anthony; Hawthorne, Dana; Macagno, Angel; Koester, Linda; Sides, Brenda; Bridwell, Keith; Lenke, Lawrence; Shufflebarger, Harry

    2009-08-15

    Multicenter analysis of 2 groups of patients surgically treated for Lenke 5C adolescent idiopathic scoliosis (AIS). Compare patients with Lenke 5C scoliosis surgically treated with anterior spinal fusion with dual rod instrumentation and anterior column support with patients surgically treated with posterior release and pedicle screw instrumentation. Treatment of single, structural, lumbar, and thoracolumbar curves in patients with AIS has been the subject of some debate. Advocates of the anterior approach assert that their technique spares posterior musculature and may save distal fusion levels, and that with dual rods and anterior column support the issues with nonunion and kyphosis have been obviated. Advocates of the posterior approach assert that with the change to posterior pedicle screw based instrumentation that correction and levels are equivalent, and the posterior approach avoids the issues with nonunion and kyphosis. This report directly compares the results of posterior versus anterior instrumented fusions in the operative treatment of adolescent idiopathic Lenke 5C curves. We analyzed 62 patients with Lenke 5C based on radiographic and clinical data at 2 institutions: 31 patients treated with posterior, pedicle-screw instrumented fusions at 1 institution (group PSF); and 31 patients with anterior, dual-rod instrumented fusions at another institution (group ASF). Multiple clinical and radiographic parameters were evaluated and compared. The mean age, preoperative major curve magnitude, and preoperative lowest instrumented vertebral (LIV) tilt were similar in both groups (age: PSF = 15.5 years, ASF = 15.6 years; curve size: PSF = 50.3 degrees +/- 7.0 degrees , ASF = 49.0 degrees +/- 6.6 degrees ; LIV tilt: PSF = 27.5 degrees +/- 6.5 degrees , ASF = 27.8 degrees +/- 6.2 degrees ). After surgery, the major curve corrected to an average of 6.3 degrees +/- 3.2 degrees (87.6% +/- 5.8%) in the PSF group, compared with 12.1 degrees +/- 7.4 degrees (75

  7. 1997 Volvo Award winner in clinical studies. The effect of pedicle screw instrumentation on functional outcome and fusion rates in posterolateral lumbar spinal fusion: a prospective, randomized clinical study.

    Science.gov (United States)

    Thomsen, K; Christensen, F B; Eiskjaer, S P; Hansen, E S; Fruensgaard, S; Bünger, C E

    1997-12-15

    A prospective randomized clinical study. To evaluate supplementary pedicle screw fixation (Cotrel-Dubousset) in posterolateral lumbar spinal fusion. The rationale behind lumbar fusion is to eliminate pathologic motion to relieve pain. To improve fusion rates and to allow reduction, a rigid transpedicular screw fixation may be beneficial, but the positive effect of this may be counter-balanced by an increase in complications. The inclusion criteria were severe, chronic low back pain from spondylolisthesis Grades 1 and 2 or from primary or secondary degenerative segmental instability. One hundred thirty patients were randomly allocated to receive no instrumentation (n = 66) or Cotrel-Dubousset instrumentation (n = 64) in posterolateral lumbar fusion. Variables were registered at the time of surgery and at 1 and 2 years after surgery. Follow-up was achieved in 97.7% of the patients. Fusion rates deduced from plain radiographs were not significantly different between instrumented and noninstrumented groups. The functional outcome assessed by the Dallas Pain Questionnaire improved significantly in both groups, and there were no significant differences in results between the two groups, except for significantly better (P < 0.06) functional outcome in relation to daily activities in the instrumented group when neural decompression had been performed. The global patients' satisfaction was 82% in the instrumented group versus 74% in the noninstrumented group (not significant). Fixation of instrumentation increased operation time, blood loss, and early reoperation rate significantly. Patients experienced only a few minor postoperative complications; none were major. Two infections appeared in the Cotrel-Dubousset group. Significant symptoms from misplacement of pedicle screws were seen in 4.8% of the instrumented patients. Lumbar posterolateral fusion with pedicle screw fixation increases the operation time, blood loss, and reoperation rate, and leads to a significant risk

  8. ANT Advanced Neural Tool

    Energy Technology Data Exchange (ETDEWEB)

    Labrador, I.; Carrasco, R.; Martinez, L.

    1996-07-01

    This paper describes a practical introduction to the use of Artificial Neural Networks. Artificial Neural Nets are often used as an alternative to the traditional symbolic manipulation and first order logic used in Artificial Intelligence, due the high degree of difficulty to solve problems that can not be handled by programmers using algorithmic strategies. As a particular case of Neural Net a Multilayer Perception developed by programming in C language on OS9 real time operating system is presented. A detailed description about the program structure and practical use are included. Finally, several application examples that have been treated with the tool are presented, and some suggestions about hardware implementations. (Author) 15 refs.

  9. Navigation of Pedicle Screws in the Thoracic Spine with a New Electromagnetic Navigation System: A Human Cadaver Study

    National Research Council Canada - National Science Library

    Hahn, Patrick; Oezdemir, Semih; Komp, Martin; Giannakopoulos, Athanasios; Kasch, Richard; Merk, Harry; Liermann, Dieter; Godolias, Georgios; Ruetten, Sebastian

    2015-01-01

    .... In addition to the standard techniques, several new techniques have been developed. The objective of this cadaveric study was to examine the accuracy of a new electromagnetic navigation system for instrumentation of pedicle screws in the spine...

  10. Basic Study for Ultrasound-Based Navigation for Pedicle Screw Insertion Using Transmission and Backscattered Methods: e0122392

    National Research Council Canada - National Science Library

    Ziqiang Chen; Bing Wu; Xiao Zhai; Yushu Bai; Xiaodong Zhu; Beier Luo; Xiao Chen; Chao Li; Mingyuan Yang; Kailiang Xu; Chengcheng Liu; Chuanfeng Wang; Yingchuan Zhao; Xianzhao Wei; Kai Chen; Wu Yang; Dean Ta; Ming Li

    2015-01-01

      The purpose of this study was to understand the acoustic properties of human vertebral cancellous bone and to study the feasibility of ultrasound-based navigation for posterior pedicle screw fixation...

  11. Genetic algorithm based on optimization of neural network structure for fault diagnosis of the clutch retainer mechanism of MF 285 tractor

    Directory of Open Access Journals (Sweden)

    S. F Mousavi

    2016-09-01

    Full Text Available Introduction The diagnosis of agricultural machinery faults must be performed at an opportune time, in order to fulfill the agricultural operations in a timely manner and to optimize the accuracy and the integrity of a system, proper monitoring and fault diagnosis of the rotating parts is required. With development of fault diagnosis methods of rotating equipment, especially bearing failure, the security, performance and availability of machines has been increasing. In general, fault detection is conducted through a specific procedure which starts with data acquisition and continues with features extraction, and subsequently failure of the machine would be detected. Several practical methods have been introduced for fault detection in rotating parts of machineries. The review of the literature shows that both Artificial Neural Networks (ANN and Support Vector Machines (SVM have been used for this purpose. However, the results show that SVM is more effective than Artificial Neural Networks in fault detection of such machineries. In some smart detection systems, incorporating an optimized method such as Genetic Algorithm in the Neural Network model, could improve the fault detection procedure. Consequently, the fault detection performance of neural networks may also be improved by combining with the Genetic Algorithm and hence will be comparable with the performance of the Support Vector Machine. In this study, the so called Genetic Algorithm (GA method was used to optimize the structure of the Artificial Neural Networks (ANN for fault detection of the clutch retainer mechanism of Massey Ferguson 285 tractor. Materials and Methods The test rig consists of some electro mechanical parts including the clutch retainer mechanism of Massey Ferguson 285 tractor, a supporting shaft, a single-phase electric motor, a loading mechanism to model the load of the tractor clutch and the corresponding power train gears. The data acquisition section consists of a

  12. Accuracy of C2 pedicle screw placement using the anatomic freehand technique.

    Science.gov (United States)

    Bydon, Mohamad; Mathios, Dimitrios; Macki, Mohamed; De la Garza-Ramos, Rafael; Aygun, Nafi; Sciubba, Daniel M; Witham, Timothy F; Gokaslan, Ziya L; Bydon, Ali; Wolinksy, Jean-Paul

    2014-10-01

    The objective of this study is to evaluate the incidence and prognostic factors of breach rates following the placement of C2 pedicle screws using the anatomic, freehand technique. We retrospectively reviewed the medical records of all patients who underwent C2 transpedicular instrumentation over six years at a single institution. All intraoperative, image-guided techniques were excluded. Breaches were ascertained from immediate postoperative CT images. All images were analyzed by three independent reviewers. The screw length was correlated with (1) the breach rate and (2) the breach severity. Severity of the breached screws reflects the screw circumference (0-360°) perforating the pedicle wall (Grade 1-Grade 4). Of the 341 C2 pedicle screws inserted in 181 patients, the average screw length was 22.93±3.7mm. The average distance from the foramen transversarium to the screw insertion point was 13.17±2.63mm. The distance from the medial rim of the pedicle to the dura of spinal cord was 3.53±1.57mm. Of the 341 screws, the overall breach rate was 17.3% (n=59). Of the 59 breaches, 89.83% of screws (n=53) breaching the spinal canal was statistically significantly higher than the 10.17% of screws (n=6) breaching the foramen transversarium (pGrade 1, 16 (27.1%) Grade 2, 6 (10.2%) Grade 3, and 10 (16.9%) Grade 4. None of the C2 breaches resulted in neurological sequela. No association was found between breach rate and gender, race or age. While the average screw length was 22.93±3.7mm [12-34mm], screw length did not predict a cortical violation (p=0.4) or severity of the breach (p=0.42) in a multiple regression model. In this cohort study on the anatomic freehand placement of C2 pedicle screws, the breach rate was 17.3%. Lateral breaches were more common than medial breaches. Screw length was not statistically correlated with cortical violation or severity of breach. Therefore, screw length is not a prognostic factor for C2 pedicle screw misplacement. Copyright © 2014

  13. Internal fixation and muscle pedicle bone grafting in femoral neck fractures

    Directory of Open Access Journals (Sweden)

    Gupta A

    2008-01-01

    Full Text Available Background: The treatment of displaced intracapsular femoral neck fracture is still an unsolved problem. Non-union and avascular necrosis are the two main complications of this fracture, especially if patient presents late. Muscle pedicle bone grafting has been advocated to provide additional blood supply. We present analysis of our 32 cases of displaced femoral neck fracture treated by internal fixation and quadratus femoris based muscle pedicle bone grafting. Materials and Methods: Open reduction and internal fixation with muscle pedicle grafting was done in 32 patients. The age of patients varied from 14-62 years (average age 45 years with male to female ratio of 13:3. Twenty-nine fractures were more than three weeks old. All the cases were treated by Meyers′ procedure. The fracture was internally fixed after open reduction and then a muscle pedicle graft was applied. It was supplemented by cancellous bone graft in seven cases. Fixation was done by parallel cancellous lag screws ( n = 19, crossed Garden′s screws ( n = 7, parallel Asnis screws ( n = 5 and Moore′s pin ( n = 1.Quadratus femoris muscle pedicle graft was used in 32 cases. In the initial 12 cases the graft was fixed with circumferential proline sutures, but later, to provide a secure fixation, the graft was fixed with a cancellous screw ( n = 20. Postoperative full weight bearing was deferred to an average of 10 weeks. Results: Union was achieved in 26/29 (89.65% cases which could be followed for an average period of 3.4 years, (2-8.5 years with good functional results and had the ability to squat and sit cross-legged. Results were based on hip rating system given by Salvatti and Wilson. The results were excellent in 15 cases, good in four cases, fair in four cases and poor in six cases. Complications were avascular necrosis ( n = 2, transient foot drop ( n = 2, coxa-vara ( n = 1 and temporary loss of scrotal sensation ( n = 1. Conclusion: Muscle pedicle bone grafting with

  14. Fretting corrosion behavior of nitinol spinal rods in conjunction with titanium pedicle screws.

    Science.gov (United States)

    Lukina, Elena; Kollerov, Mikhail; Meswania, Jay; Khon, Alla; Panin, Pavel; Blunn, Gordon W

    2017-03-01

    Untypical corrosion damage including erosions combined with the build-up of titanium oxide as a corrosion product on the surface of explanted Nitinol spinal rods in the areas where it was in contact with titanium pedicle screw head is reported. It was suggested that Nitinol rods might have inferior fretting corrosion resistance compared with that made of titanium or CoCr. Fretting corrosion of Nitinol spinal rods with titanium (Ti6Al4V) pedicle screws were tested in-vitro by conducting a series of potentiostatic measurements of the peak-to-peak values of fretting corrosion current under bending in a 10% solution of calf serum in PBS. The test included Nitinol rods locked in titanium pedicle screws of different designs. Performance of commercially available titanium (Ti6Al4V) and CoCr spinal rods was also investigated for a comparison. Corrosion damage observed after the in-vitro tests was studied using SEM and EDAX analysis and was compared with patterns on Nitinol rods retrieved 12months after initial surgery. Metal ions level was measured in the test media after in-vitro experiments and in the blood and tissues of the patients who had the rods explanted. The results of this study revealed that Nitinol spinal rods locked in Ti pedicle screws are susceptible to fretting corrosion demonstrating higher fretting corrosion current compared with commercially used Ti6Al4V and CoCr rods. On the surface of Nitinol rods after in-vitro tests and on those retrieved from the patients similar corrosion patterns were observed. Improved resistance to fretting corrosion was observed with Nitinol rods in the in-vitro tests where pedicle screws were used with a stiffer locking mechanism. Since the development of the localized corrosion damage might increase the risk of premature fatigue failure of the rods and result in leaching of Ni ions, it is concluded that Nitinol rods should not be used in conjunction with Ti pedicle screws without special protection especially where the

  15. Characteristics of immediate and fatigue strength of a dual-threaded pedicle screw in cadaveric spines.

    Science.gov (United States)

    Brasiliense, Leonardo B C; Lazaro, Bruno C R; Reyes, Phillip M; Newcomb, Anna G U S; Turner, Joseph L; Crandall, Dennis G; Crawford, Neil R

    2013-08-01

    Novel dual-threaded screws are configured with overlapping (doubled) threads only in the proximal shaft to improve proximal cortical fixation. Tests were run to determine whether dual-threaded pedicle screws improve pullout resistance and increase fatigue endurance compared with standard pedicle screws. In vitro strength and fatigue tests were performed in human cadaveric vertebrae and in polyurethane foam test blocks. Seventeen cadaveric lumbar vertebrae (14 pedicles) and 40 test sites in foam blocks were tested. Measures for comparison between standard and dual-threaded screws were bone mineral density (BMD), screw insertion torque, ultimate pullout force, peak load at cyclic failure, and pedicular side of first cyclic failure. For each vertebral sample, dual-threaded screws were inserted in one pedicle and single-threaded screws were inserted in the opposite pedicle while recording insertion torque. In seven vertebrae, axial pullout tests were performed. In 10 vertebrae, orthogonal loads were cycled at increasing peak values until toggle exceeded threshold for failure. Insertion torque and pullout force were also recorded for screws placed in foam blocks representing healthy or osteoporotic bone porosity. In bone, screw insertion torque was 183% greater with dual-threaded than with standard screws (pscrews pulled out at 93% of the force required to pull out dual-threaded screws (p=.42). Of 10 screws, five reached toggle failure first on the standard screw side, two screws failed first on the dual-threaded side, and three screws failed on both sides during the same round of cycling. In the high-porosity foam, screw insertion torque was 60% greater with the dual-threaded screw than with the standard screw (p=.005), but 14% less with the low-porosity foam (p=.07). Pullout force was 19% less with the dual-threaded screw than with the standard screw in the high-porosity foam (p=.115), but 6% greater with the dual-threaded screw in the low-porosity foam (p=.156

  16. Outcomes of posterior lumbar interbody fusion with Pedicle Screw fixation using two different Types of Titan Cages

    OpenAIRE

    Abbushi, Alexander

    2010-01-01

    This is a retrospective study of 40 patients, who had a monosegmental lumbar degenerative spondylolisthesis treated by monosegmental posterior lumbar interbody fusion (PLIF) using two different types of titan cages and pedicle screw fixation. The objective was to evaluate the radiographic and clinical results of these patients treated with posterior lumbar interbody fusion and pedicle screw fixation either by using the Prospace Titan Cage of Aesculap or the O.I.C Titan Cage of Stryker. ...

  17. Posterior lumber interbody fusion with pedicle screw fixation for the management of spondylolisthesis: An analysis of 40 cases

    OpenAIRE

    Md. Rezaul Amin; Md. Atikur Rahman; Akhlaque Hossain Khan; Haradhan Devnath; A. B. M. Manwar Hossain; Motashimul Hasan; Kanak Kanti Barua

    2017-01-01

    Spondylolisthesis is forward slipping of upper vertebra in relations to its lower one, commonest is L4-L5. The ideal surgical treatment of spondylolisthesis is still controversial. Posterior lumber interbody fusion with pedicle fixation is one of treatment choices for the lumber spondylolisthesis. Forty patients who operated through posterior lumber interbody fusion and pedicle screw fixation by single surgeon was included from January 2012 to March 2015. Periodical follow-up was done both cl...

  18. Can the Interspinous Device, SPIRE(TM), be an Alternative Fixation Modality in Posterior Lumbar Fusion Instead of Pedicle Screw?

    Science.gov (United States)

    Lee, Chang-Hyun; Hyun, Seung-Jae; Kim, Ki-Jeong; Jahng, Tae-Ahn; Kim, Hyun-Jib

    2017-01-01

    Although conventional posterior lumbar interbody fusion (PLIF) using pedicle screws provides successful outcomes, pedicle screw related complications are sometimes noted. SPIRE? was invented as an interspinous fixation device (ISD) to replace pedicle screw. The aim of this study is to evaluate the clinical and radiological outcomes in patients who underwent unilateral PLIF using SPIRE? compared with a pedicle screw. All consecutive patients who show medically intractable lumbar degenerative disease with unilateral radiculopathy and mild instability were enrolled. Thirteen patients who underwent the PLIF using SPIRE? (ISD group), and age, gender, and index level matched patients who underwent the PLIF using pedicle screw (PS group) were recruited in a 1:1 ratio. Pain, Oswestry Disability Index (ODI), disc height, and slippage were evaluated. Both PS and ISD groups revealed significant improvement and there was no significant difference between them (back pain, p=0.18; leg pain, p=0.51; ODI, p=0.82). Although the ISD group showed spondylolisthesis for the first 3 months after the surgery, there was no significant difference compared with the PS group (p=0.65). Disc height decreased in both the ISD group (10.8 mm?7.7 mm) and the PS group (12.8 mm?10.8 mm), and this difference had statistical significance (p PLIF demonstrates comparable clinical outcomes with pedicle screw. It may provide weak fixation but it is acceptable. This technique may be an alternative for the patients with unilateral radiculopathy and mild instability.

  19. Modeling a Neural Network as a Teaching Tool for the Learning of the Structure-Function Relationship

    Science.gov (United States)

    Salinas, Dino G.; Acevedo, Cristian; Gomez, Christian R.

    2010-01-01

    The authors describe an activity they have created in which students can visualize a theoretical neural network whose states evolve according to a well-known simple law. This activity provided an uncomplicated approach to a paradigm commonly represented through complex mathematical formulation. From their observations, students learned many basic…

  20. Anconeus Muscle-Pedicle Bone Graft With Periosteal Coverage for Osteochondritis Dissecans of the Humeral Capitellum.

    Science.gov (United States)

    Shimada, Kozo; Temporin, Ko; Oura, Keiichiro; Tanaka, Hiroyuki; Noguchi, Ryosuke

    2017-09-01

    Treatment of advanced osteochondritis dissecans (OCD) of the capitellum is controversial, especially in moderate-sized lesions. To establish a treatment algorithm for capitellum OCD, we tried to determine the utility of and problems associated with anconeus muscle-pedicle bone graft with periosteal coverage (ABGP) for the treatment of moderate-sized articular OCD defects of the capitellum. Case series; Level of evidence, 4. According to our protocol for elbow OCD, 16 patients (15 males, 1 female; age range, 12-17 years; mean age, 14.4 years) with a moderate-sized OCD lesion of the humeral capitellum were treated with ABGP. All patients had a full-thickness, unstable OCD lesion that was 10 to 15 mm in diameter. Clinical results and postoperative images, including radiographs and magnetic resonance imaging (MRI), were evaluated at a mean follow-up of 31 months (range, 24-66 months). All but 1 patient had functional improvement after the procedure and returned to previous sporting activities within 6 months. One female patient needed 1 year for functional recovery due to development of postoperative chronic regional pain syndrome (CRPS). Two patients required additional surgery, including shaving of the protruding cartilage, and they returned to their previous level of activity. Mean arc of range of flexion-extension motion was 117° preoperatively and 129° at follow-up (P = .031). Mean elbow function as assessed with the clinical rating system of Timmerman and Andrews was 136 preoperatively and 186 at follow-up (P = .00012). Bony union of the graft as demonstrated by trabecular bone bridging on radiography was obtained within 3 months in all patients. Postoperative MRI was examined for 14 patients at 6 to 12 months after the procedure; the MRIs showed near-normal articular surface integrity in 9 of the 14 patients (64%) and underlying bony structure in 10 of the 14 patients (71%). Improvement after ABGP was obtained within 6 months in all except 1 patient, who

  1. Pedicle frozen autograft for limb sparing surgery in a dog with femoral osteosarcoma

    Directory of Open Access Journals (Sweden)

    Aline Silva Gouvêa

    Full Text Available ABSTRACT: Osteosarcoma (OSA is the most common bone tumor diagnosed in dogs and represents approximately 85% of canine skeletal tumors. The most commonly employed therapy is amputation of the limb followed by chemotherapy. However, preservation of the afflicted limb has been successful for patients with concomitant neurological or orthopedic conditions, which are contraindications to the complete amputation, or with owners reluctant to the possibility of amputation. For these reasons, the purpose of this study was to describe the technical procedures that allowed limb salvage through the use of pedicle frozen grafts in a dog with femoral OSA. Surgical procedures consisted of a femoral diaphyseal osteotomy with tearing of the soft tissues; thus, creating a bone pedicle that was frozen in liquid nitrogen according to the protocol outlined by TSUCHIYA et al. (2005. Limb function remained satisfactory for six months.

  2. Congenital aplastic-hypoplastic lumbar pedicle in infants and young children

    Energy Technology Data Exchange (ETDEWEB)

    Yousefzadeh, D.K.; El-Khoury, G.Y.; Lupetin, A.R.

    1982-01-01

    Nine cases of congenital aplastic-hypoplastic lumbar pedicle (mean age 27 months) are described. Their data are compared to those of 18 other reported cases (mean age 24.7 years) and the following conclusions are made: (1) Almost exclusively, the pedicular defect in infants and young children is due to developmental anomaly rather than destruction by malignancy or infectious processes. (2) This anomaly, we think, is more common than it is believed to be. (3) Unlike adults, infants and young children rarely develop hypertrophy and/or sclerosis of the contralateral pedicle. (4) Detection of pedicular anomaly is more than satisfying a radiographic curiosity and may lead to discovery of other coexisting anomalies. (5) Ultrasonic screening of the patients with congenital pedicular defects may detect the associated genitourinary anomalies, if present, and justify further studies in a selected group of patients.

  3. Misdiagnosing absent pedicle of cervical spine in the acute trauma setting

    Directory of Open Access Journals (Sweden)

    Fahad H. Abduljabbar

    2015-09-01

    Full Text Available Congenital absence of cervical spine pedicle can be easily misdiagnosed as facet dislocation on plain radiographs especially in the acute trauma setting. Additional imaging, including computed tomography (CT-scan with careful interpretation is required in order to not misdiagnose cervical posterior arch malformation with subsequent inappropriate management. A 39-year-old patient presented to the emergency unit of our university hospital after being trampled by a cow over her back and head followed by loss of consciousness, retrograde amnesia and neck pain. Her initial cervical CT-scan showed possible C5-C6 dislocation, then, it became clear that her problem was a misdiagnosed congenital cervical abnormality. Patient was treated symptomatically without consequences. The congenital absence of a cervical pedicle is a very unusual condition that is easily misdiagnosed. Diagnosis can be accurately confirmed with a CT-scan of the cervical spine. Symptomatic conservative treatment will result in resolution of the symptoms.

  4. Pedicled buccal fat pad graft for root coverage in severe gingival recession defect

    Directory of Open Access Journals (Sweden)

    Saurav Panda

    2016-01-01

    Full Text Available Gingival recession (GR is a condition resulting in root exposure which leads to root sensitivity, pain, root caries, plaque retention, poor esthetics, and tooth loss. Sites exhibiting Miller Class III and IV GR are not suitable for treatment with surgical root coverage techniques, and their prognosis are very poor with current techniques. In this case report, pedicled buccal fat pad (PBFP was employed as subepithelial graft technique for root coverage of maxillary tooth with Class III GR defect along with furcation involvement and the absence of keratinized gingiva. PBFP as the subepithelial graft is likely to increase the predictability and outcome of root coverage procedures in the treatment of cases with poor prognosis, owing to its pedicled vascularity. PBFP may be considered as a reliable modality for root coverage of such severe maxillary posterior GR defects, as reported, that could not be repaired by other conventional procedures.

  5. Spondylolisthesis on bilateral pedicle stress fracture in the lumbar spine: a case study.

    Science.gov (United States)

    Hajjioui, A; Khazzani, H; Sbihi, S; Bahiri, R; Benchekroune, B; Hajjaj-Hassouni, N

    2011-02-01

    We report the clinical case of a 54-year-old woman presenting radicular low back pain on the right side of L4 associated to spondylolisthesis on L4-L5, without any notion of trauma or spine surgery. Furthermore this patient is regularly seen for benign rheumatoid polyarthritis complicated by steroid-induced osteoporosis. A preventive treatment was implanted with good results on pain improvement and functional capacities. For pedicle fractures the literature review reports several different etiologies: spontaneous fractures, hereditary fractures or stress-related fractures. There was a discussion on the various treatments available and in this case of spondylolisthesis on pedicle fracture a conservative treatment was implemented similar to the one for isthmic spondylolisthesis. It yielded satisfying results. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  6. [Plastic Reconstruction with a Vascular Pedicle Latissimus Dorsi Flap after Sternal Osteomyelitis].

    Science.gov (United States)

    Spindler, N; Langer, S

    2017-10-01

    Objective: Sternal bone and soft tissue debridement after osteomyelitis of the sternum with simultaneous defect coverage using a vascular pedicle latissimus dorsi flap. Indication: Profound sternal wound healing disorders may be covered with various flap grafts. The latissimus dorsi flap provides a fast, sufficient and reliable option to cover sternal defects. If the bone and soft tissue debridement has been very radical, coverage may be performed in a one-stage procedure. Method: The individual surgical steps for sternal debridement with simultaneous defect coverage using a vascular pedicle latissimus dorsi flap are shown. Conclusion: The radicality of debridement is crucial to treatment success and allows debridement and flap graft coverage to be performed at the same time. If two surgeons work simultaneously, the duration of surgery may be significantly reduced. Georg Thieme Verlag KG Stuttgart · New York.

  7. Innovative use of laterally positioned periosteal pedicle graft for coverage of gingivitis artefacta

    Science.gov (United States)

    Mechery, Reenesh; Harshavardhana, Babu; Rath, Saroj Kumar; Dinakar, Nithya

    2016-01-01

    There are many etiological factors for nonplaque-induced gingival diseases, out of which physical trauma due to psychiatric reasons leading to self-infliction is less studied upon. This case report presents one such case which has been successfully treated stepwise where psychological counseling was done to restrain from habit followed by using an innovative laterally positioned periosteal pedicle graft for dehiscence coverage. PMID:29238148

  8. Anconeus Muscle-Pedicle Bone Graft With Periosteal Coverage for Osteochondritis Dissecans of the Humeral Capitellum

    OpenAIRE

    Shimada, Kozo; Temporin, Ko; Oura, Keiichiro; Tanaka, Hiroyuki; Noguchi, Ryosuke

    2017-01-01

    Background: Treatment of advanced osteochondritis dissecans (OCD) of the capitellum is controversial, especially in moderate-sized lesions. Purpose: To establish a treatment algorithm for capitellum OCD, we tried to determine the utility of and problems associated with anconeus muscle-pedicle bone graft with periosteal coverage (ABGP) for the treatment of moderate-sized articular OCD defects of the capitellum. Study Design: Case series; Level of evidence, 4. Methods: According to our protocol...

  9. Feasibility and Accuracy of Thoracolumbar Minimally Invasive Pedicle Screw Placement With Augmented Reality Navigation Technology.

    Science.gov (United States)

    Elmi-Terander, Adrian; Nachabe, Rami; Skulason, Halldor; Pedersen, Kyrre; Söderman, Michael; Racadio, John; Babic, Drazenko; Gerdhem, Paul; Edström, Erik

    2017-12-19

    Cadaveric laboratory study. To assess the feasibility and accuracy of minimally invasive thoracolumbar pedicle screw placement using augmented reality (AR) surgical navigation SUMMARY OF BACKGROUND DATA.: Minimally invasive spine (MIS) surgery has increasingly become the method of choice for a wide variety of spine pathologies. Navigation technology based on AR has been shown to be feasible, accurate and safe in open procedures. AR technology may also be used for MIS surgery. The AR surgical navigation was installed in a hybrid operating room (OR). The hybrid OR includes a surgical table, a motorized flat detector C-arm with intraoperative 2D/3D imaging capabilities, integrated optical cameras for AR navigation and patient motion tracking using optical markers on the skin. Navigation and screw placement was without any X-ray guidance. Two neurosurgeons placed 66 Jamshidi needles (2 cadavers) and 18 cannulated pedicle screws (1 cadaver) in the thoracolumbar spine. Technical accuracy was evaluated by measuring the distance between the tip of the actual needle position and the corresponding planned path as well as the angles between the needle and the desired path. Time needed for navigation along the virtual planned path was measured. An independent reviewer assessed the postoperative scans for the pedicle screws' clinical accuracy. Navigation time per insertion was 90 ± 53 seconds with an accuracy of 2.2 ± 1.3 mm. Accuracy was not dependent on operator. There was no correlation between navigation time and accuracy. The mean error angle between the Jamshidi needles and planned paths was 0.9 ± 0.8°. No screw was misplaced outside the pedicle. Two screws breached 2 to 4 mm yielding an overall accuracy of 89% (16/18). MIS screw placement directed by AR with intraoperative 3D imaging in a hybrid OR is accurate and efficient, without any fluoroscopy or X-ray imaging during the procedure. 4.

  10. Cervical pedicle screw fixation at C6 and C7 A cadaveric study

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    Ye Li

    2015-01-01

    Conclusion: The intersection of the horizontal line through the midpoint of the transverse process root and vertical line through the intersection of the posterolateral and posterior planes of the isthmus can be used as an entry point for C6 and C7 pedicle screw fixation. The screws should be inserted at 60 or 90° with the posterolateral isthmus in the horizontal plane and at 75° with the posterior isthmus in the sagittal plane. The LSC should not exceed 30 mm.

  11. Comparison of Cranial Facet Joint Violation Rate Between Percutaneous and Open Pedicle Screw Placement

    Science.gov (United States)

    Wang, Liang; Wang, Yipeng; Yu, Bin; Li, Zhengyao; Li, Ye

    2015-01-01

    Abstract Percutaneous and open pedicle screw placements have been widely used in lumbar fusion surgery. However, there are conflicting reports of cranial facet joint violation rate for the 2 techniques. To better determine the rate of cranial facet joint violation, a systematic review and meta-analysis was performed in the present study. We searched the established electronic literature databases including MEDLINE, EMBASE, World of Science, and the Cochrane Central Register of Controlled Trials databases for trials involving the 2 pedicle screw placement techniques. Odds ratio (OR) and 95% confidence interval (CI) were calculated. Four comparative trials with a cumulative sample size of 881 patients and 1755 cranial pedicle screws were identified and analyzed. The results showed that cranial facet joint violation rate was 18.18% (154/847) in percutaneous group and 18.72% (170/908) in open group. The pooled data revealed that there was no significant difference in the violation rate (OR 0.75, 95% CI 0.24–2.30, P = 0.62). In addition, there was also no significant difference for the rate of severe violation between the 2 techniques (OR 1.20, 95% CI 0.55–2.62, P = 0.64, random effect model). Based on the current data, the meta-analysis shows that similar cranial facet joint violation rate occurs during the percutaneous and open pedicle screw placement techniques. In addition, taking the limitations of this study into consideration, it was still not appropriate to draw such a strong conclusion. More well-designed prospective randomized controlled trials are needed to assess violation rate for the 2 techniques in the future. PMID:25654397

  12. Modified sacrospinalis muscle pedicle bone graft for fusion of isthmic spondylolisthesis

    OpenAIRE

    Adam, Faisal F.

    2001-01-01

    We treated 20 patients with symptomatic L4–5 isthmic spondylolisthesis (ten grade I, nine grade II and one grade III) surgically. All patients complained of low back pain and nine had additional radicular pain. Bilateral posterolateral fusion using the sacrospinalis muscle as a muscle pedicle bone graft was carried out in all patients. Decompression was added in patients with radiculopathy. Follow-up ranged from 12 to 28 months. Pain relief was graded as excellent in 18 patients, radiographic...

  13. Repair of a cerebrospinal fluid fistula using a muscle pedicle flap: technical case report.

    Science.gov (United States)

    Hyun, Seung-Jae; Rhim, Seung-Chul; Ra, Young-Shin

    2009-12-01

    As a late complication of radiation therapy and a transoral approach, a cerebrospinal fluid (CSF) fistula between an oropharyngeal cavity and the ventral dura of the cervical spine is an extremely rare event. There are often difficulties in repairing ventral dural defects. Herein, we describe a technique that assists in feasible repair of a CSF fistula associated with ventral dural defects. A 36-year-old man was admitted to our institution with postnasal drip and a progressive spastic gait disturbance. Eleven years earlier, he had a recurrent chordoma of the cervical spine, which was treated by 5 open surgeries, including a transoral operation, and 6 rounds of radiation therapy. A neuroradiological examination revealed a CSF fistula between a posterior pharyngeal wall and the ventral dura of the cervical spine. We performed a repair operation of the CSF fistula using a conventional direct posterior approach. However, we were unable to repair the fistula using a dural-substitute suturing procedure. Therefore, we used a semispinalis cervicis muscle pedicle flap. The muscle pedicle flap was brought through the dural defect in the anterior part of the posterior pharyngeal wall, to which it was fixed. It was then used to reinforce the suture line that closed the fistula and to fill the fistula tract. After posterior surgery, a transoral endoscopic approach was used to augment the muscle pedicle flap with a bovine pericardial patch graft. No postoperative complications occurred, and CSF leaking ceased after surgery. There was no CSF leakage during the 1-year follow-up period. This novel muscle pedicle flap technique for repairing a CSF fistula can be used as an alternative to the direct "water-tight" closure of ventral cervical dural defects.

  14. Comparison of low density and high density pedicle screw instrumentation in Lenke 1 adolescent idiopathic scoliosis.

    Science.gov (United States)

    Shen, Mingkui; Jiang, Honghui; Luo, Ming; Wang, Wengang; Li, Ning; Wang, Lulu; Xia, Lei

    2017-08-02

    The correlation between implant density and deformity correction has not yet led to a precise conclusion in adolescent idiopathic scoliosis (AIS). The aim of this study was to evaluate the effects of low density (LD) and high density (HD) pedicle screw instrumentation in terms of the clinical, radiological and Scoliosis Research Society (SRS)-22 outcomes in Lenke 1 AIS. We retrospectively reviewed 62 consecutive Lenke 1 AIS patients who underwent posterior spinal arthrodesis using all-pedicle screw instrumentation with a minimum follow-up of 24 months. The implant density was defined as the number of screws per spinal level fused. Patients were then divided into two groups according to the average implant density for the entire study. The LD group (n = 28) had fewer than 1.61 screws per level, while the HD group (n = 34) had more than 1.61 screws per level. The radiographs were analysed preoperatively, postoperatively and at final follow-up. The perioperative and SRS-22 outcomes were also assessed. Independent sample t tests were used between the two groups. Comparisons between the two groups showed no significant differences in the correction of the main thoracic curve and thoracic kyphosis, blood transfusion, hospital stay, and SRS-22 scores. Compared with the HD group, there was a decreased operating time (278.4 vs. 331.0 min, p = 0.004) and decreased blood loss (823.6 vs. 1010.9 ml, p = 0.048), pedicle screws needed (15.1 vs. 19.6, p density and high density pedicle screw instrumentation achieved satisfactory deformity correction in Lenke 1 AIS patients. However, the operating time and blood loss were reduced, and the implant costs were decreased with the use of low screw density constructs.

  15. The Application of "Renal Pedicle Rotation" Method in Retroperitoneal Laparoscopic Partial Nephrectomy for Renal Ventral Tumors.

    Science.gov (United States)

    Song, Shiyu; Zhang, Hongxian; Ma, Lulin; Huang, Yi; Zhao, Lei; Wang, Guoliang; Lu, Jian; Zhang, Shudong

    2015-09-01

    To present preliminary experience of "renal pedicle rotation" method in retroperitoneal laparoscopic partial nephrectomy (RLPN) for renal ventral tumors. A retrospective analysis of renal surgery database about patients undergoing RLPN was conducted. We identified 14 consecutive cases of all the surgeries from December 2013 to October 2014 with renal ventral tumors. The 14 surgeries were all in the application of renal pedicle rotation method, an intraoperative skill in which surgeons rotates the kidney on renal pedicle axis after separating renal artery and vein for a better tumor exposure. A total of 14 patients underwent RLPN. All surgeries were successful without conversion to radical nephrectomy or open partial nephrectomy. The mean operative time was 171.1±47.2 min (range 83-246), the mean warm ischemia time was 15.9±9.8 min (range 7-35) and the mean estimated blood loss was 89.3±102.2 mL (range 10-300). Mean postoperative hospital stay was 6.2±1.9 days (range 4-10) and mean retroperitoneal drainage was 4.2±1.4 days (range 2-8). No intraoperative complications occurred. Postoperative complications developed in four patients. All patients had negative margins and pathological examination revealed 10 (71.4%) clear cell carcinomas, two (14.2%) epithelial renal angiomyolipoma, one (7.1%) papillary carcinoma and one (7.1%) nephrotuberculosis. The review of the early oncologic outcomes revealed no local recurrence and distant metastasis. The renal pedicle rotation method might be a feasible and safe procedure to get a better tumor exposure for incision and suture in renal ventral tumors RLPN surgeries with acceptable postoperative outcomes.

  16. C2 Pars/Pedicle Screws in Management of Craniocervical and Upper Cervical Instability

    OpenAIRE

    Eshra, Mohammed Ahmed

    2014-01-01

    Study Design A retrospective study. Purpose To evaluate the efficacy and the safety of craniocervical and upper cervical stabilization by using C2 pars/pedicle screw fixations. Overview of Literature The management of craniocervical and upper cervical instability has progressed over the past two decades due to good achievements in the instrumentation and the increased awareness on spinal anatomy and biomechanics. However, there is insufficient studies or solid conclusions on this topic, thus,...

  17. Use of intraoperative isocentric C-arm 3D fluoroscopy for sextant percutaneous pedicle screw placement: case report and review of the literature.

    Science.gov (United States)

    Acosta, Frank L; Thompson, Timothy L; Campbell, Stacey; Weinstein, Philip R; Ames, Christopher P

    2005-01-01

    Three-dimensional (3D) fluoroscopy-based image guidance system using an isocentric C-arm (Iso-C) fluoroscope was shown to be as effective as computed tomography-based systems in guiding the accurate percutaneous placement of lumbar pedicle screws in cadavers. To date, however, no description is available of the intraoperative use of 3D fluoroscopy to guide lumbar pedicle screw placement in an actual spinal fusion procedure. We report a case in which isocentric 3D fluoroscopic images, along with image-guidance software, were used to guide the placement of percutaneous pedicle screws for fusion in a patient with degenerative spondylolisthesis. Operating room of a large academic medical center during the placement of percutaneous pedicle screws in a patient with degenerative spondylolisthesis. A percutaneous dynamic reference array was attached to the L3 spinous process. A satisfactory image set was obtained and automatically registered. The L4 and L5 pedicles were localized, and pedicle holes were then cannulated, drilled and tapped. A screw was then inserted using the Sextant system for percutaneous pedicle screws. In this manner, bilateral pedicle screws were inserted into the L4-L5 pedicles. All steps of pedicle cannulation were performed under Iso-C 3D image guidance. A postoperative computed tomography scan showed accurate placement of all pedicle screws. The patient experienced an improvement in leg pain with no new neurologic deficits. The present case is the first case to demonstrate the intraoperative use of a 3D fluoroscopy-based image-guidance system for accurate navigation during lumbar pedicle screw placement.

  18. Basic study for ultrasound-based navigation for pedicle screw insertion using transmission and backscattered methods.

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    Ziqiang Chen

    Full Text Available The purpose of this study was to understand the acoustic properties of human vertebral cancellous bone and to study the feasibility of ultrasound-based navigation for posterior pedicle screw fixation in spinal fusion surgery. Fourteen human vertebral specimens were disarticulated from seven un-embalmed cadavers (four males, three females, 73.14 ± 9.87 years, two specimens from each cadaver. Seven specimens were used to measure the transmission, including tests of attenuation and phase velocity, while the other seven specimens were used for backscattered measurements to inspect the depth of penetration and A-Mode signals. Five pairs of unfocused broadband ultrasonic transducers were used for the detection, with center frequencies of 0.5 MHz, 1 MHz, 1.5 MHz, 2.25 MHz, and 3.5 MHz. As a result, good and stable results were documented. With increased frequency, the attenuation increased (P0.05. At about 0.6 cm away from the cortical bone, warning signals were easily observed from the backscattered measurements. In conclusion, the ultrasonic system proved to be an effective, moveable, and real-time imaging navigation system. However, how ultrasonic navigation will benefit pedicle screw insertion in spinal surgery needs to be determined. Therefore, ultrasound-guided pedicle screw implantation is theoretically effective and promising.

  19. Treatment of neuromuscular scoliosis with posterior-only pedicle screw fixation

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    Fernandez Harry M

    2008-06-01

    Full Text Available Abstract Background To determine whether posterior-only approach using pedicle screws in neuromuscular scoliosis population adequately addresses the correction of scoliosis and maintains the correction over time. Methods Between 2003 and 2006, 26 consecutive patients (7 cerebral palsy, 10 Duchenne muscular dystrophy, 5 spinal muscular atrophy and 4 others with neuromuscular scoliosis underwent posterior pedicle screw fixation for the deformity. Preoperative, immediate postoperative and final follow-up Cobb's angle and pelvic obliquity were analyzed on radiographs. The average age of the patients was 17.5 years (range, 8–44 years and the average follow-up was 25 months (18–52 months. Results Average Cobb's angle was 78.53° before surgery, 30.70° after surgery (60.9% correction, and 33.06° at final follow-up (57.9% correction showing significant correction (p Conclusion Results indicate that in patients with neuromuscular scoliosis, acceptable amounts of curve correction can be achieved and maintained with posterior-only pedicle screw instrumentation without anterior release procedure.

  20. Translocated pedicled buccal fat pad: closure of anterior and middle skull base defects after tumor resection.

    Science.gov (United States)

    Cherekaev, Vasily A; Golbin, Denis A; Belov, Alexander I

    2012-01-01

    Problem of closure of skull base defects after removal of craniobasal lesions, especially, craniofacial, is one of the most challenging in neurosurgery. Persistent skull base defect produces extremely high risk of cerebrospinal fluid leaks and consecutive infectious complications. Local pedicled grafts are the preferred material for plasty. In this study, the authors present original technique of using a pedicled buccal fat pad (BFP) graft. Anatomy and functions of BFP are discussed in details as well as surgical technique illustrated by 2 case reports. From 2004 to 2010, 188 patients with anterior and middle skull base mass lesions were operated on in Burdenko Neurosurgical Institute (Moscow, Russia) using BFP as plastic material for closure of different defects (male-female ratio=61:127; mean age was 47 years [range, 10-74 years]). In 93.6% of cases, pedicled BFP flap was applied; in 6.4%, free flap was used. Follow-up period ranged between 1 and 7 years. Only 1 case of postoperative cerebrospinal fluid leak was observed; flap rejection was not registered in the series. High effectiveness and minimal invasiveness are principal advantages of the described technique, which is applied in neurosurgery for the first time. Other benefits include proximity of donor site and defect, simplicity of surgical technique, minimal postoperative discomfort, and very low risk of benign complications.

  1. Interpolated conjunctival pedicle flaps for the treatment of exposed glaucoma drainage devices.

    Science.gov (United States)

    Godfrey, David G; Merritt, James H; Fellman, Ronald L; Starita, Richard J

    2003-12-01

    To describe an alternative method to repair exposed glaucoma drainage devices (GDDs) when conventional attempts have failed. Four eyes, from 3 patients, with severe ocular surface disease were included in the study. All eyes had previously received a Baerveldt GDD for uncontrollable intraocular pressure and postoperatively had exposed GDDs. The conjunctival defects were unrepairable with a scleral patch or pericardium, conjunctival advancement, or a conjunctival patch graft. Two eyes had chemical burns, one eye had extensive scarring from multiple surgical procedures, and one patient had rheumatoid arthritis. Each patient provided informed consent, and was given the option of removing the GDD and undergoing diode cyclophotocoagulation or attempting to save the GDD by a conjunctival pedicle flap. An interpolated conjunctival pedicle flap was taken from the cul-de-sac (fornix). The conjunctiva and Tenon capsule were incised radially to the tube, rotated from the fornix at a 90 degrees angle, and sutured to the remaining healthy conjunctiva to cover the exposed tube. Postoperatively, all eyes had vascularized flaps that showed viable tissue. All eyes retained the GDDs, and the intraocular pressure has been under control during follow-up (7, 13, 25, and 27 months). Interpolated conjunctival pedicle flaps seem to be a viable alternative to repairing exposed GDDs when other methods are impractical or impossible.

  2. Traumatic subluxation associated with absent cervical pedicle: case report and review of the literature.

    Science.gov (United States)

    Moon, Sung-Jun; Lee, Jung-Kil; Seo, Bo-Ra; Kim, Soo-Han

    2008-08-15

    Case description. To describe a case of traumatic subluxation in association with a congenitally absent cervical pedicle, and review the pertinent medical literature. The congenital absence of a cervical pedicle is a relatively uncommon developmental anomaly that is frequently mistaken for a unilateral facet fracture-dislocation in the context of acute trauma. Because there is little evidence of recovery after surgery, and the symptoms are usually not disabling, surgery is not recommended for most cases. A 62-year-old man presented with severe neck and right shoulder pain after falling. Plain radiographs and computed tomography of the cervical spine showed the typical features of a congenitally absent pedicle at C6 with anterolisthesis of C6 on C7. We performed anterior interbody fusion at C6-C7 because of persistent neck pain and progressive instability. Complete restoration of the C6-C7 subluxation was achieved with resolution of the presenting symptoms. At 18 months follow-up, flexion and extension dynamic radiographs demonstrated good alignment with solid fusion at C6-C7. Although conservative treatment is the primary treatment for this clinical entity, surgery is an alternative option for those patients who fail to achieve recovery after conservative treatment or exhibit instability.

  3. Laparoscopic harvesting of omental pedicle flap for cerebral revascularization in children with moyamoya disease.

    Science.gov (United States)

    Bruzoni, Matias; Steinberg, Gary K; Dutta, Sanjeev

    2016-04-01

    An abundance of angiogenic and immunologic factors makes the omentum an ideal tissue for reconstruction and revascularization of a variety of extraperitoneal wounds and defects. Omental harvesting was historically performed through a large laparotomy and subcutaneous tunneling to the site of disease. Several complications of the open procedure including abdominal wound infection, fascial dehiscence, ventral hernia, and postoperative ileus have been described. The use of laparoscopy to harvest the omentum has the potential to reduce such complications. We describe the surgical technique and outcomes of a series of patients undergoing laparoscopic pedicled omental flap mobilization for cerebral revascularization in moyamoya disease. A retrospective chart review of all patients undergoing laparoscopic omental cerebral transposition for moyamoya disease between 2011 and 2014 was performed. Clinical indication, surgical technique, operative times, complications, and outcomes at follow-up were reviewed. A total of 7 children underwent the procedure. The general surgery team performed laparoscopic omental mobilization, extraperitonealization, and subcutaneous tunneling, while the neurosurgical team performed craniotomy and cerebral application of the graft. The patients were followed postoperatively with clinic visits and angiography. There was one intraoperative complication (colon injury) and one postoperative complication (intermittent omental hernia at fascial defect for pedicle). All patients had partial to complete symptomatic resolution and demonstrated adequate intracranial revascularization on angiography. Laparoscopic omental pedicle flap mobilization and subcutaneous transposition is feasible in children who require salvage cerebral revascularization for moyamoya disease. The procedure should be considered for other conditions requiring extraperitoneal revascularization. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Minimally invasive treatment of unstable pelvic ring injuries with modified pedicle screw-rod fixator.

    Science.gov (United States)

    Wu, Xiao-Tian; Liu, Zuo-Qing; Fu, Wen-Qin; Zhao, Shan

    2018-01-01

    Objective To evaluate the clinical application of the minimally invasive modified pedicle screw-rod fixator for unstable pelvic ring injuries, including its feasibility, merits, and limitations. Methods Twenty-three patients (13 males, 10 females; average age, 36.3 years) with unstable pelvic ring injuries underwent anterior fixation using a modified pedicle screw-rod fixator with or without posterior fixation using a transiliac internal fixator. The clinical findings were assessed using Majeed scores. The quality of reduction was evaluated using the Matta criteria. Results Clinical results at 1 year postoperatively were excellent in 14 patients, good in 7, and fair in 2. The two patients with fair results had intermittent pain at the sacroiliac joint because of the posterior implant. One woman complained of persistent pain at the pubic tubercle during sexual intercourse. Iatrogenic neuropraxia of the unilateral lateral femoral cutaneous nerve occurred in three patients. Unilateral femoral nerve palsy occurred in one patient. The quality of fracture reduction was excellent in 12 patients, good in 8, and fair in 3. Heterotopic ossification occurred in eight patients; all were asymptomatic. Conclusions Minimally invasive modified pedicle screw-rod fixation is an effective alternative treatment for pelvic ring injuries.

  5. Optical imaging of neuronal activity and visualization of fine neural structures in non-desheathed nervous systems.

    Directory of Open Access Journals (Sweden)

    Christopher John Goldsmith

    Full Text Available Locating circuit neurons and recording from them with single-cell resolution is a prerequisite for studying neural circuits. Determining neuron location can be challenging even in small nervous systems because neurons are densely packed, found in different layers, and are often covered by ganglion and nerve sheaths that impede access for recording electrodes and neuronal markers. We revisited the voltage-sensitive dye RH795 for its ability to stain and record neurons through the ganglion sheath. Bath-application of RH795 stained neuronal membranes in cricket, earthworm and crab ganglia without removing the ganglion sheath, revealing neuron cell body locations in different ganglion layers. Using the pyloric and gastric mill central pattern generating neurons in the stomatogastric ganglion (STG of the crab, Cancer borealis, we found that RH795 permeated the ganglion without major residue in the sheath and brightly stained somatic, axonal and dendritic membranes. Visibility improved significantly in comparison to unstained ganglia, allowing the identification of somata location and number of most STG neurons. RH795 also stained axons and varicosities in non-desheathed nerves, and it revealed the location of sensory cell bodies in peripheral nerves. Importantly, the spike activity of the sensory neuron AGR, which influences the STG motor patterns, remained unaffected by RH795, while desheathing caused significant changes in AGR activity. With respect to recording neural activity, RH795 allowed us to optically record membrane potential changes of sub-sheath neuronal membranes without impairing sensory activity. The signal-to-noise ratio was comparable with that previously observed in desheathed preparations and sufficiently high to identify neurons in single-sweep recordings and synaptic events after spike-triggered averaging. In conclusion, RH795 enabled staining and optical recording of neurons through the ganglion sheath and is therefore both a

  6. Structural alterations in rat liver proteins due to streptozotocin-induced diabetes and the recovery effect of selenium: Fourier transform infrared microspectroscopy and neural network study

    Science.gov (United States)

    Bozkurt, Ozlem; Haman Bayari, Sevgi; Severcan, Mete; Krafft, Christoph; Popp, Jürgen; Severcan, Feride

    2012-07-01

    The relation between protein structural alterations and tissue dysfunction is a major concern as protein fibrillation and/or aggregation due to structural alterations has been reported in many disease states. In the current study, Fourier transform infrared microspectroscopic imaging has been used to investigate diabetes-induced changes on protein secondary structure and macromolecular content in streptozotocin-induced diabetic rat liver. Protein secondary structural alterations were predicted using neural network approach utilizing the amide I region. Moreover, the role of selenium in the recovery of diabetes-induced alterations on macromolecular content and protein secondary structure was also studied. The results revealed that diabetes induced a decrease in lipid to protein and glycogen to protein ratios in diabetic livers. Significant alterations in protein secondary structure were observed with a decrease in α-helical and an increase in β-sheet content. Both doses of selenium restored diabetes-induced changes in lipid to protein and glycogen to protein ratios. However, low-dose selenium supplementation was not sufficient to recover the effects of diabetes on protein secondary structure, while a higher dose of selenium fully restored diabetes-induced alterations in protein structure.

  7. Ergotropic effect of bone cement on pedicle screw fixation in treatment of osteoporotic thoracolumbar fracture

    Directory of Open Access Journals (Sweden)

    Da LIU

    2017-02-01

    Full Text Available Objective To evaluate the ergotropic effect of bone cement on pedicle screw fixation in treatment of osteopo¬rotic thoracolumbar fracture. Methods Fifty-three patients with osteoporotic thoracolumbar fracture, admitted from Jun. 2013 to Dec. 2014, were included for treatment by augmentation of pedicle screw fixation with bone cement. All patients underwent pre-operative examination of bone mineral density with T-score ≤-2.5 and augmentation of pedicle screw fixation with injection of 1.5 ml bone cement in adjacent to fractured vertebra. All patients were treated with anti-osteoporosis therapy pre- and post-operation, ob¬served and recorded with basic conditions and complications. At pre-operation, one-week post-operation and last follow-up, pain vi¬sual analogue scale (VAS and neurological function score (ASIA of all patients were recorded, and the compression rats of anterior and posterior edge of fractured vertebra, and compression rats of spinal canal and Cobb angel of all patients were measured. Results All the 53 patients were successfully undergone operation in about 90-140 min with blood loss of about 150-350 ml. No spinal cord or nerve injury, dural tear and obvious leakage of bone cement and screw loosening occurred during operation. All patients were followed up for 12 to 36 months and the neurological function obviously recovered contrasted with pre-operation. X-ray and CT examination at last follow-up showed good fractures healing, good position and non-loosening of internal fixation device and non-leakage of bone cement. At one week post-operation and last follow-up, VAS, compression rats of anterior edge and posterior edge of fractured vertebra, compression rats of spinal canal and Cobb angel were significantly lower than those at pre-operation (P0.05. Conclusions Augmentation of pedicle screw fixation with bone cement can effectively strengthen the initial stability of pedicle screw in osteo¬porosis, restore the

  8. Pedicle screw versus hybrid construct instrumentation in adolescent idiopathic scoliosis: meta-analysis of thoracic kyphosis.

    Science.gov (United States)

    Cao, Yun; Xiong, Wei; Li, Feng

    2014-06-01

    A quantitative meta-analysis was conducted on publishing studies reporting results of spinal surgery in adolescent idiopathic scoliosis with instrumentation of pedicle screw or hybrid construct. The primary objective is to get overview of the power to restore thoracic kyphosis using 2 different instrumentations. During the past years, surgery has mainly focused on correcting the coronal curve, but nowadays, the aims of posterior fusion and instrumentation are to achieve a stable, well-balanced spine in the coronal as well as in the sagittal planes. A PubMed and EMBASE search was conducted using combinations of the key words "hybrid construct" or "pedicle screw" with "adolescent idiopathic scoliosis" up to October 2013. A hand search of reference lists of obtained articles was also performed. A total of 24 studies were identified and included in this meta-analysis. Of this, 12 included pedicle screw group only, 5 included hybrid construct group only, and 7 included both groups. The total number of patients was 1615. Age ranged from 9 to 26 years, with a mean of 15. For pedicle screw group, we got standard mean difference (SMD) as 0.40 (95% confidence interval, 0.31-0.50); I= 91.4%. For hybrid construct group, we got SMD as 0.15 (95% confidence interval, 0.04-0.26). Both intervals of SMD lay in positive value side. Overall SMD was 0.30 (95% confidence interval, 0.23-0.37). The positive value of SMD means thoracic kyphosis improves after surgery, whereas negative value means kyphosis loss after surgery. There is overall tendency for both instrumentations to restore thoracic kyphosis. Hybrid construct seems to be more powerful in restoring kyphosis than pedicle screw. Preoperative important factor was found to be reasonably distributed or balanced. For operative factor, rod stiffness, fashion of hybrid construct, in situ bending, and rod rotation maneuver could have influence on results of kyphosis in different ways. Loss of correction and limited restoration of loss

  9. Biomechanical Comparisons of Pull Out Strengths After Pedicle Screw Augmentation with Hydroxyapatite, Calcium Phosphate, or Polymethylmethacrylate in the Cadaveric Spine.

    Science.gov (United States)

    Yi, Seong; Rim, Dae-Cheol; Park, Seoung Woo; Murovic, Judith A; Lim, Jesse; Park, Jon

    2015-06-01

    In vertebrae with low bone mineral densities pull out strength is often poor, thus various substances have been used to fill screw holes before screw placement for corrective spine surgery. We performed biomechanical cadaveric studies to compare nonaugmented pedicle screws versus hydroxyapatite, calcium phosphate, or polymethylmethacrylate augmented pedicle screws for screw tightening torques and pull out strengths in spine procedures requiring bone screw insertion. Seven human cadaveric T10-L1 spines with 28 vertebral bodies were examined by x-ray to exclude bony abnormalities. Dual-energy x-ray absorptiometry scans evaluated bone mineral densities. Twenty of 28 vertebrae underwent ipsilateral fluoroscopic placement of 6-mm holes augmented with hydroxyapatite, calcium phosphate, or polymethylmethacrylate, followed by transpedicular screw placements. Controls were pedicle screw placements in the contralateral hemivertebrae without augmentation. All groups were evaluated for axial pull out strength using a biomechanical loading frame. Mean pedicle screw axial pull out strength compared with controls increased by 12.5% in hydroxyapatite augmented hemivertebrae (P = 0.600) and by 14.9% in calcium phosphate augmented hemivertebrae (P = 0.234), but the increase was not significant for either method. Pull out strength of polymethylmethacrylate versus hydroxyapatite augmented pedicle screws was 60.8% higher (P = 0.028). Hydroxyapatite and calcium phosphate augmentation in osteoporotic vertebrae showed a trend toward increased pedicle screw pull out strength versus controls. Pedicle screw pull out force of polymethylmethacrylate in the insertion stage was higher than that of hydroxyapatite. However, hydroxyapatite is likely a better clinical alternative to polymethylmethacrylate, as hydroxyapatite augmentation, unlike polymethylmethacrylate augmentation, stimulates bone growth and can be revised. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. 3D printing-assisted preoperative plan of pedicle screw placement for middle-upper thoracic trauma: a cohort study.

    Science.gov (United States)

    Xu, Wei; Zhang, Xuming; Ke, Tie; Cai, Hongru; Gao, Xiang

    2017-08-11

    This study aimed to evaluate the application of 3D printing in assisting preoperative plan of pedicle screw placement for treating middle-upper thoracic trauma. A preoperative plan was implemented in seven patients suffering from middle-upper thoracic (T3-T7) trauma between March 2013 and February 2016. In the 3D printing models, entry points of 56 pedicle screws (Magerl method) and 4 important parameters of the pedicle screws were measured, including optimal diameter (ϕ, mm), length (L, mm), inclined angle (α), head-tilting angle (+β), and tail-tilting angle (-β). In the surgery, bare-hands fixation of pedicle screws was performed using 3D printing models and the measured parameters as guidance. A total of seven patients were enrolled, including five men and two women, with the age of 21-62 years (mean age of 37.7 years). The position of the pedicle screw was evaluated postoperatively using a computerized tomography scan. Totally, 56 pedicle screws were placed, including 33 pieces of level 0, 18 pieces of level 1, 4 pieces of level 2 (pierced lateral wall), and 1 piece of level 3 (pierced lateral wall, no adverse consequences), with a fine rate of 91.0%. 3D printing technique is an intuitive and effective assistive technology to pedicle screw fixation for treating middle-upper thoracic vertebrae, which improve the accuracy of bare-hands screw placement and reduce empirical errors. The trial was approved by the Ethics Committee of the Fujian Provincial Hospital. It was registered on March 1st, 2013, and the registration number was K2013-03-001.

  11. Proximal instrumented vertebral body chance fracture after pedicle screw instrumentation in a thoracic kyphosis patient with osteoporosis.

    Science.gov (United States)

    Hu, Xiaobang; Lieberman, Isador H

    2015-02-01

    We present a case of proximal vertebral body chance fracture after pedicle screw instrumentation and fusion in a 67-year-old woman with osteoporosis and thoracic kyphosis. To report the rare and unique complication of proximal vertebral body chance fracture after pedicle screw instrumentation and fusion in a kyphosis patient. Pedicle screw instrumentation has been associated with complications not limited to neurological or vascular injury, loss of curve correction, intraoperative pedicle fracture or loosening, dural laceration, deep infection, and pseudarthrosis. To the best of our knowledge, there are no previous reports describing a chance-type fracture generated by a pedicle screw fixation at the proximal end of a construct. A 67-year-old woman suffered from progressive thoracic kyphosis and mid thoracic pain presented 2 weeks after pedicle screw instrumentation and correction. She developed a vertebral body fracture at the proximal end of the instrumentation construct. Surgical intervention, including removal of the screws in the fractured vertebrae and extension of the instrumented fusion across the cervicothoracic junction, effectively restored the physiological sagittal alignment. Postoperatively, at 12-month follow-up, the patient is doing exceptionally well with near-complete relief of back pain and an excellent maintenance of correction. Chance fracture in osteoporotic bone at the proximal end of a construct due to a pedicle screw is a rare complication but it may result in catastrophic consequences. Early recognition of this complication, reduction of the fraction-dislocation, and an extension of the instrumentation can be utilized for realignment and long-term stabilization.

  12. Is There Benefit to Free Over Pedicled Vascularized Grafts in Augmenting Tibial Intercalary Allograft Constructs?

    Science.gov (United States)

    Manfrini, Marco; Bindiganavile, Srimanth; Say, Ferhat; Colangeli, Marco; Campanacci, Laura; Depaolis, Massimiliano; Ceruso, Massimo; Donati, Davide

    2017-05-01

    Intercalary reconstruction of tibial sarcomas with vascularized fibula autografts and massive bone allografts is reliable with predictable long-term results. However, inadequate data exist comparing free and pedicled vascularized fibula autografts in combination with a massive bone allograft in patients undergoing intercalary tibia reconstructions. Among patients undergoing large-segment intercalary allografting, we sought to compare supplemental free vascularized fibular autografts with supplemental pedicled vascularized fibular autografts, in terms of (1) oncologic results, (2) complications associated with surgery, (3) Musculoskeletal Tumor Society (MSTS) scores, and (4) surgical time. Between 1994 and 2013, we treated 320 patients, younger than 40 years, with tibial sarcomas. Thirty-five patients (11%) underwent amputations. One hundred ninety-five patients (61%) were treated with intraarticular resection of the tibia, which constituted 104 tumor endoprostheses, 63 proximal tibia allograft prosthetic composites, 21 osteoarticular allografts, and seven arthrodeses with allografts. Ninety patients (28%) underwent joint-sparing intercalary reconstruction. Forty-one (13%) of these 90 patients were treated with allografts alone, two (1%) with vascularized fibula grafts, and 47 (15%) with intercalary allografts supplemented by autografts (free fibular autografts, 22 patients, 7%; pedicled fibular autografts, 25 patients, 8%). During the study period, we used free vascularized fibular autografts in association with massive bone allograft for a resection longer than 12 cm with a very small periarticular residual segment. The choice for using a pedicled fibula harvested in the ipsilateral leg initially was for patients having only diaphyseal resections and the indication was later extended to intraepiphyseal osteotomies with a small periarticular residual segment. The goals of this study are to present the long-term results in this group of patients and compare their

  13. Error Analysis and Experimental Study of a Bi-Planar Parallel Mechanism in a Pedicle Screw Robot System.

    Science.gov (United States)

    Duan, Qingjuan; Du, Zhijiang; Yu, Hongjian; Wang, Yongfeng; Dong, Wei

    2016-11-30

    Due to the urgent need for high precision surgical equipment for minimally invasive spinal surgery, a novel robot-assistant system was developed for the accurate placement of pedicle screws in lumbar spinal surgeries. The structure of the robot was based on a macro-micro mechanism, which includes a serial mechanism (macro part) and a bi-planar 5R parallel mechanism (micro part). The macro part was used to achieve a large workspace, while the micro part was used to obtain high stiffness and accuracy. Based on the transfer function of dimension errors, the factors affecting the accuracy of the end effectors were analyzed. Then the manufacturing errors and joint angle error on the position-stance of the end effectors were investigated. Eventually, the mechanism of the strain energy produced by the deformation of linkage via forced assembly and displacements of the output point were calculated. The amount of the transfer errors was quantitatively analyzed by the simulation. Experimental tests show that the error of the bi-planar 5R mechanism can be controlled no more than 1 mm for translation and 1° for rotation, which satisfies the required absolute position accuracy of the robot.

  14. Error Analysis and Experimental Study of a Bi-Planar Parallel Mechanism in a Pedicle Screw Robot System

    Directory of Open Access Journals (Sweden)

    Qingjuan Duan

    2016-11-01

    Full Text Available Due to the urgent need for high precision surgical equipment for minimally invasive spinal surgery, a novel robot-assistant system was developed for the accurate placement of pedicle screws in lumbar spinal surgeries. The structure of the robot was based on a macro-micro mechanism, which includes a serial mechanism (macro part and a bi-planar 5R parallel mechanism (micro part. The macro part was used to achieve a large workspace, while the micro part was used to obtain high stiffness and accuracy. Based on the transfer function of dimension errors, the factors affecting the accuracy of the end effectors were analyzed. Then the manufacturing errors and joint angle error on the position-stance of the end effectors were investigated. Eventually, the mechanism of the strain energy produced by the deformation of linkage via forced assembly and displacements of the output point were calculated. The amount of the transfer errors was quantitatively analyzed by the simulation. Experimental tests show that the error of the bi-planar 5R mechanism can be controlled no more than 1 mm for translation and 1° for rotation, which satisfies the required absolute position accuracy of the robot.

  15. Neural stem cells and neuro/gliogenesis in the central nervous system: understanding the structural and functional plasticity of the developing, mature, and diseased brain.

    Science.gov (United States)

    Yamaguchi, Masahiro; Seki, Tatsunori; Imayoshi, Itaru; Tamamaki, Nobuaki; Hayashi, Yoshitaka; Tatebayashi, Yoshitaka; Hitoshi, Seiji

    2016-05-01

    Neurons and glia in the central nervous system (CNS) originate from neural stem cells (NSCs). Knowledge of the mechanisms of neuro/gliogenesis from NSCs is fundamental to our understanding of how complex brain architecture and function develop. NSCs are present not only in the developing brain but also in the mature brain in adults. Adult neurogenesis likely provides remarkable plasticity to the mature brain. In addition, recent progress in basic research in mental disorders suggests an etiological link with impaired neuro/gliogenesis in particular brain regions. Here, we review the recent progress and discuss future directions in stem cell and neuro/gliogenesis biology by introducing several topics presented at a joint meeting of the Japanese Association of Anatomists and the Physiological Society of Japan in 2015. Collectively, these topics indicated that neuro/gliogenesis from NSCs is a common event occurring in many brain regions at various ages in animals. Given that significant structural and functional changes in cells and neural networks are accompanied by neuro/gliogenesis from NSCs and the integration of newly generated cells into the network, stem cell and neuro/gliogenesis biology provides a good platform from which to develop an integrated understanding of the structural and functional plasticity that underlies the development of the CNS, its remodeling in adulthood, and the recovery from diseases that affect it.

  16. Application of a novel 3D drill template for cervical pedicle screw tunnel design: a cadaveric study.

    Science.gov (United States)

    Yu, Zhengxi; Zhang, Guodong; Chen, Xuanhuang; Chen, Xu; Wu, Changfu; Lin, Yijun; Huang, Wenhua; Lin, Haibin

    2017-06-10

    To develop and validate the efficacy and accuracy of a three-dimensional (3D) computed tomography (CT) reconstructive rapid prototyping drill template for cervical pedicle screw placement. CT thin-layer scans were obtained from 12 adult cadaveric cervical specimens and reconstructed. The ideal screw channels were chosen by analyzing the cross sections of the reconstructed 3D images. The navigation templates were designed and printed based on the optimal screw channels. The pedicle screws were placed on the cadaver specimens under template guidance, and the cadaver specimens were scanned and reconstructed. The pre- and post-operative models were compared. Entry point and exit point data of these two models were collected and compared using the Chi-square test. A total of 164 cervical pedicle screws were placed; among them, six punctured the cortical bone of the vertebral pedicle reaching an accuracy of 96.3%. Among the outside screws, all of the deviation distances were 3D CT reconstructive rapid prototyping drill template combined with the screw tunnel design based on 3D cutting technique can help facilitate accurate cervical pedicle screw insertion.

  17. Accuracy and postoperative assessment of pedicle screw placement during scoliosis surgery with computer-assisted navigation: a meta-analysis.

    Science.gov (United States)

    Tian, Wei; Zeng, Cheng; An, Yan; Wang, Chao; Liu, Yajun; Li, Jianing

    2017-03-01

    Accurate insertion of pedicle screws in scoliosis patients is a challenge for surgeons. Computer-assisted navigation techniques might help improve the accuracy of screw placement, thereby avoiding complications. Thus, the objective of this present work is to compare the accuracy and postoperative assessment of pedicle screw placement in scoliosis patients using a computer-assisted navigation technique and using a conventional free-hand method. A search of the PubMed, Cochrane, and Web of Science databases was executed. In vivo comparative studies that assessed the accuracy and postoperative evaluation of pedicle screw placement in scoliosis patients with or without navigation techniques were chosen and analyzed. The accuracy of pedicle screw insertion was significantly increased when using the navigation system, although the average operative time and correction rate was not significantly different from that with non-navigated surgery. The navigation technique improves the accuracy of pedicle screw placement during scoliosis surgery without prolonging the operative time or decreasing the deformity correction effect. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  18. Novel quantum inspired binary neural network algorithm

    Indian Academy of Sciences (India)

    In this paper, a quantum based binary neural network algorithm is proposed, named as novel quantum binary neural network algorithm (NQ-BNN). It forms a neural network structure by deciding weights and separability parameter in quantum based manner. Quantum computing concept represents solution probabilistically ...

  19. Traumatic Fracture of Thin Pedicles Secondary to Extradural ...

    African Journals Online (AJOL)

    the surrounding structures, hyperintense signal to the. CSF on T2, partial enhancement with contrast, and possible signal void on the fast spin echo sequence ... cyst. To better define the point of communication, a diluted Omnipaque (GE Healthcare) was injected into the cyst in order to obtain an intraoperative myelogram.

  20. Adaptive neural control of MIMO nonlinear systems with a block-triangular pure-feedback control structure.

    Science.gov (United States)

    Chen, Zhenfeng; Ge, Shuzhi Sam; Zhang, Yun; Li, Yanan

    2014-11-01

    This paper presents adaptive neural tracking control for a class of uncertain multiinput-multioutput (MIMO) nonlinear systems in block-triangular form. All subsystems within these MIMO nonlinear systems are of completely nonaffine pure-feedback form and allowed to have different orders. To deal with the nonaffine appearance of the control variables, the mean value theorem is employed to transform the systems into a block-triangular strict-feedback form with control coefficients being couplings among various inputs and outputs. A systematic procedure is proposed for the design of a new singularity-free adaptive neural tracking control strategy. Such a design procedure can remove the couplings among subsystems and hence avoids the possible circular control construction problem. As a consequence, all the signals in the closed-loop system are guaranteed to be semiglobally uniformly ultimately bounded. Moreover, the outputs of the systems are ensured to converge to a small neighborhood of the desired trajectories. Simulation studies verify the theoretical findings revealed in this paper.

  1. Use of the Composite Pedicled Pectoralis Minor Flap after Resection of Soft Tissue Sarcoma in Reconstruction of the Glenohumeral Joint

    Directory of Open Access Journals (Sweden)

    Michiel A. J. van de Sande

    2014-01-01

    Full Text Available The surgical repair of an extensive anterior glenohumeral soft tissue defect is complicated by glenohumeral instability and subsequent significant functional deficit. This surgical note offers a relatively simple reconstruction of the anterior capsule and subscapularis muscle using a pectoralis minor pedicle flap. This reconstruction is supplemented with functional reconstruction of the anterior glenohumeral joint. A conventional deltopectoral approach is utilized and pectoralis minor is freed from its coracoid insertion, released, and mobilized without compromising the pedicle entering from the dorsum and inferior one-third of the muscle. The mobilized pectoralis minor vascular pedicle has sufficient length for the pectoralis minor to be transferred to provide coverage of the anterior shoulder joint even in full external rotation, providing anterior stability. To further improve glenohumeral stability and shoulder function, the pectoralis major muscle can be split with the clavicular part reinserted lateral to the bicipital groove onto the lesser tuberosity replacing subscapularis function while stabilising the glenohumeral joint.

  2. Pullout strength of pedicle screws augmented with particulate calcium phosphate: an experimental study.

    Science.gov (United States)

    Hashemi, Ata; Bednar, Drew; Ziada, Samir

    2009-05-01

    Pressure-injected and in situ curing bone cements have been studied as alternatives in augmenting lumbar pedicle screw fixation but are frequently found to leak outside the confines of the target vertebra. The objective is set to determine the mechanical efficacy of a porous granular/particulate calcium phosphate (CP) bone augmentation product (Skelite) applied manually without pressurized injection in this application. The biomechanical analysis compared the axial pullout strength and insertional torque of augmented and nonaugmented pedicle screws in cellular polyurethane foams. The insertion torque and pullout strength of 6.5-mm pedicle screws inserted (via 3.5-mm pilot holes) into polyurethane blocks mimicking the porosity of cancellous bone were measured. New pilot holes were then packed with granular particles of Skelite and retested. Last, those blocks initially tested to failure without augmentation were packed with Skelite and retested. Measurements were performed for polyurethane densities of 0.16 and 0.32 g/cc (corresponding to the porosity of osteoporotic and normal bone) and strain rates of 0.5 and 5mm/min. Peak pullout force averaged 2132.5+/-119.3 N and 1840.1+/-216.7 N in high density samples without and with augmentation and 688.2+/-91.4 N and 861.6+/-74.5 N in low density samples without and with augmentation. After failure, approximately 50% and 77% of the peak pullout force of original high and low density samples was regained by augmentation. Statistical analysis revealed significant (p<.0001) correlation between the addition of CP, peak pullout resistance, and insertion torque. Granular CP augmentation improved the pullout strength in both failed (pulledout) samples and low density (porosity of osteoporotic cancellous bone) polyurethane blocks.

  3. Unilateral pedicle screws asymmetric tethering: an innovative method to create idiopathic deformity

    Directory of Open Access Journals (Sweden)

    Zhang Xuesong

    2007-10-01

    Full Text Available Abstract Objective To evaluate the feasibility of the method that unilateral pedicle screws asymmetric tethering in concave side in combination with convex rib resection for creating idiopathic deformity. Summary of background data Various methods are performed to create idiopathic deformity. Among these methods, posterior asmmetric tethering of the spine shows satisfying result, but some drawbacks related to the current posterior asymmetric tether were still evident. Materials and methods Unilateral pedicle screws asymmetric tethering was performed to 14 female goats (age: 5–8 week-old, weight: 6–8 kg in concave side in combination with convex rib resection. Dorsoventral and lateral plain radiographs were taken of each thoracic spine in the frontal and sagittal planes right after the surgery and later every 4 weeks. Results All animals ambulated freely after surgery. For technical reasons, 2 goats were excluded (one animal died for anesthetic during the surgery, and one animal was lost for instrumental fail due to postoperative infection. Radiography showed that 11 goats exhibited scoliosis with convex toward to the right side, and as the curve increased with time, only 1 goat showed nonprogressive. The initial scoliosis generated in the progressors after the procedures measured 29.0° on average (range 23.0°–38.5° and increased to 43.0° on average (range 36.0°–58.0° over 8 to 10 weeks. The average progression of 14.0° was measured. The curvature immediately after tethering surgery (the initial Cobb angle did have a highly significant correlation with the final curvature (p Conclusion Unilateral pedicle screws asymmetric tethering is a practical method to create experimental scoliosis, especially for those who would like to study the correction of this deformity.

  4. Posterior unilateral pedicle subtraction osteotomy of hemivertebra for correction of the adolescent congenital spinal deformity.

    Science.gov (United States)

    Li, Xin-Feng; Liu, Zu-De; Hu, Guang-Yu; Chen, Bin; Zhong, Gui-Bin; Zang, Wei-Ping; Wang, Han-Tao

    2011-02-01

    The treatment of adolescent congenital deformity (late-diagnosed congenital deformity) is still unknown. The best candidates for hemivertebra excision are young patients, typically between 4 and 6 years of age. Partial excision may be feasible for older children. The purpose of this study was to assess the effect of unilateral pedicle subtraction osteotomy of hemivertebra for correction of the adolescent congenital spinal deformity. Retrospective analysis. Twelve patients with adolescent congenital deformity who underwent posterior unilateral pedicle subtraction osteotomy and correction were evaluated. Mean age at the time of surgery was 17 years. The charts, standing full-length posteroanterior and lateral view radiographs, and functional measures were reviewed. For evaluation of surgical effectiveness, comparative analysis of the parameters of the total main curve, the segmental curve, the compensatory cranial and caudal curves, the segmental kyphosis, and the trunk shift before and after operation and at the most recent follow-up was done. The mean follow-up period was 40.5 months. Mean Cobb angles of the total main curve and the segmental curve were, respectively, 47.5° and 43.8° before surgery, 23.7° and 16.5° after surgery, and 22.6° and 17° at the last follow-up. The angle of segmental kyphosis was 11.8° before surgery, 6.2° after surgery, and 7.8° (range, -30° to 26°) at the final follow-up. The mean final global lordosis was within the normal range. No neurologic deficit occurred. Solid fusion was achieved for all cases. Unilateral pedicle subtraction osteotomy with instrumentation from a posterior-only approach is indicated in older teenagers for an adolescent congenital spinal deformity. Compared with hemivertebra excision, corrective surgery with hemivertebra osteotomy has a lower intraoperative blood loss and shorter operation time. Copyright © 2011 Elsevier Inc. All rights reserved.

  5. [Pedicle flaps based on the sphenopalatine artery: anatomical and surgical study].

    Science.gov (United States)

    Gras-Cabrerizo, Juan R; Gras-Albert, Juan R; Monjas-Canovas, Irene; García-Garrigós, Elena; Montserrat-Gili, Joan R; Sánchez del Campo, Francisco; Kolanczak, Katarzyna; Massegur-Solench, Humbert

    2014-01-01

    Local pedicle flaps based on the sphenopalatine artery make it possible to reconstruct large defects of the skull base (SB). From January 2008 to January 2013, 64 lesions with involvement of SB were analysed. These lesions were treated using endoscopic endonasal approach and required a pedicle flap based on the sphenopalatine artery. In addition, measurements and flexibility of the flaps were examined in 4 cadaveric nasal cavities. Surgical group. Sixty-four nasoseptal flaps (NSF) were used, in 4 cases associated with a middle turbinate flap (MTF), and in 1 case supplemented with an inferior turbinate flap (ITF). Five cerebrospinal fluid fistulas (8%) were noted. Among patients with initial lesions, 7% presented an anosmia. Cadaveric group. The length of the NSF varied between 5.2 cm and 7.7 cm and the width ranged from 3 cm to 4.5 cm. The ITF provided an anterior-posterior distance between 4.2 cm and 5 cm, with a width between 1.2 cm and 2.8 cm. The mean length of MTFs varied between 3.5 cm and 4.2 cm, with a width between 1.4 cm and 1.9 cm. The most versatile local flap for the reconstruction of skull base defects is the NSF, and flaps pedicled to the posterolateral nasal artery offer an excellent alternative. Copyright © 2013 Elsevier España, S.L. y Sociedad Española de Otorrinolaringología y Patología Cérvico-Facial. All rights reserved.

  6. Malar Augmentation with Pedicled Buccal Fat Pad in Orthognathic Surgery: Three-Dimensional Evaluation.

    Science.gov (United States)

    Hernández-Alfaro, Federico; Valls-Ontañón, Adaia; Blasco-Palacio, Julia C; Guijarro-Martínez, Raquel

    2015-11-01

    Contemporary orthognathic surgery contemplates three-dimensional facial soft-tissue harmonization as one of the basic pillars in treatment planning. In particular, prominent malar regions are regarded as a sign of beauty and youth by Western societies. The aim of this article was to perform a subjective and objective three-dimensional evaluation of the pedicled buccal fat pad technique for malar augmentation in the context of orthognathic surgery. Six consecutive patients with underlying dentofacial anomalies and bilateral malar hypoplasia were managed with simultaneous orthognathic surgery and pedicled buccal fat pad malar augmentation. Patient morbidity and satisfaction with the procedure were evaluated with a visual analogue scale. Cone-beam computed tomographic data were used to perform a volumetric analysis at 1- and 12-month follow-up by means of image superimposition. Subjective analysis revealed excellent patient satisfaction and minimal pain. Mean malar volume was 115,480.91 mm preoperatively, 124,586.32 mm 1 month after surgery, and 119,008.77 mm 12 months after surgery. Thus, the final mean increase 1 year after surgery was 3527.86 mm and the average amount of resorption was 5577.55 mm. The median variations in volume were 7.77 percent at 1-month follow-up and 3.52 percent at 12-month follow-up. In conclusion, the pedicled buccal fat pad technique is a reasonable alternative for malar augmentation in the context of orthognathic surgery. The results of this preliminary report suggest that it provides satisfactory soft-tissue augmentation; avoids the use of foreign materials; and has minimal morbidity, high patient satisfaction, and adequate stability at 12-month follow-up. Therapeutic, IV.

  7. Evaluation of pedicled omental flap delivered through a minilaparotomy for immediate breast reconstruction in obese patients.

    Science.gov (United States)

    Khater, Ashraf

    2013-12-01

    Studies have shown the laparoscopically harvested omental flap to be a successful method for immediate breast reconstruction. However, data about its usefulness and safety in obese women are limited. This study examined the effectiveness and safety of a pedicled omental flap delivered via a minilaparotomy in women with a body mass index (BMI) higher than 30 kg/m(2). Women candidates for skin-sparing mastectomy underwent reconstruction with delivery of a pedicled omental flap via a minilaparotomy. Surgery was performed for 24 women with a mean age of 57.54 years and a mean BMI of 32.54 kg/m(2). The operative time was prolonged by about 1 h without excess blood loss or prolongation of their hospital stay. Except for a single case of partial flap necrosis, no single total flap loss was recorded. In three patients (12.5 %), the flap volume was inadequate, and silicone implant was used as an adjunct. Only one patient (4 %) experienced a small incisional hernia. The majority of the patients (67 %) described their cosmetic outcome as excellent. Delivery of a pedicled omental flap via a minilaparotomy is a safe and reliable method for immediate breast reconstruction after skin-sparing mastectomy in women with a BMI higher than 30 kg/m(2). This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

  8. Localization and characterization of STRO-1 cells in the deer pedicle and regenerating antler.

    Directory of Open Access Journals (Sweden)

    Hans J Rolf

    2008-04-01

    Full Text Available The annual regeneration of deer antlers is a unique developmental event in mammals, which as a rule possess only a very limited capacity to regenerate lost appendages. Studying antler regeneration can therefore provide a deeper insight into the mechanisms that prevent limb regeneration in humans and other mammals, and, with regard to medical treatments, may possibly even show ways how to overcome these limitations. Traditionally, antler regeneration has been characterized as a process involving the formation of a blastema from de-differentiated cells. More recently it has, however, been hypothesized that antler regeneration is a stem cell-based process. Thus far, direct evidence for the presence of stem cells in primary or regenerating antlers was lacking. Here we demonstrate the presence of cells positive for the mesenchymal stem cell marker STRO-1 in the chondrogenic growth zone and the perivascular tissue of the cartilaginous zone in primary and regenerating antlers as well as in the pedicle of fallow deer (Dama dama. In addition, cells positive for the stem cell/progenitor cell markers STRO-1, CD133 and CD271 (LNGFR were isolated from the growth zones of regenerating fallow deer antlers as well as the pedicle periosteum and cultivated for extended periods of time. We found evidence that STRO-1(+ cells isolated from the different locations are able to differentiate in vitro along the osteogenic and adipogenic lineages. Our results support the view that the annual process of antler regeneration might depend on the periodic activation of mesenchymal progenitor cells located in the pedicle periosteum. The findings of the present study indicate that not only limited tissue regeneration, but also extensive appendage regeneration in a postnatal mammal can occur as a stem cell-based process.

  9. Indications, Outcomes, and Complications of Pedicled Propeller Perforator Flaps for Upper Body Defects: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Davide Lazzeri

    2013-01-01

    Full Text Available BackgroundThe aim of this investigation was to systematically review the current literature to provide the best data for indications, outcomes, survival, and complication rates of pedicled propeller perforator flaps for upper body defects.MethodsA comprehensive literature review for articles published from January 1991 to December 2011 was performed using the PubMed, Medline, and Cochrane Databases. Articles without available full-text, single case reports or papers with excessive missing data were excluded. Papers reporting pedicle-perforator (propeller flaps used for lower extremity reconstruction were excluded from meta-analysis.ResultsFrom the initial 1,736 studies our search yielded, 343 studies qualified for the second stage of selection. Of 117 full-text reports screened, 41 studies, met the definitive inclusion and exclusion criteria. Of the selected 41 articles, 26 were case series, original papers or retrospective reviews and were included, whereas 15 were case report papers and therefore were excluded. Two hundred ninety-five propeller flaps were reported to have been used in a total of 283 patients. Indications include repair of trauma-induced injuries, post-trauma revision surgery, cancer resection, chronic infection, pressure sores, and chronic ulcers with a major complication rate (3.3% comparable to that of free flaps. No specific exclusion criteria for the procedure were presented in the studies reviewed.ConclusionsPedicled propeller flaps are a versatile and safe reconstructive option that are easy and quick to raise and that provide unlimited clinical solutions because of the theoretical possibility of harvesting them based on any perforator chosen among those classified in the body.

  10. Evolvable synthetic neural system

    Science.gov (United States)

    Curtis, Steven A. (Inventor)

    2009-01-01

    An evolvable synthetic neural system includes an evolvable neural interface operably coupled to at least one neural basis function. Each neural basis function includes an evolvable neural interface operably coupled to a heuristic neural system to perform high-level functions and an autonomic neural system to perform low-level functions. In some embodiments, the evolvable synthetic neural system is operably coupled to one or more evolvable synthetic neural systems in a hierarchy.

  11. MIS Single-Position Lateral and Oblique Lateral Lumbar Interbody Fusion and Bilateral Pedicle Screw Fixation: Feasibility and Perioperative Results.

    Science.gov (United States)

    Blizzard, Daniel J; Thomas, J Alex

    2017-07-12

    Retrospective review of prospectively collected data of the first 72 consecutive patients treated with single-position one- or two-level lateral (LLIF) or oblique lateral interbody fusion (OLLIF) with bilateral percutaneous pedicle screw and rod fixation by a single spine surgeon. To evaluate the clinical feasibility, accuracy, and efficiency of a single-position technique for LLIF and OLLIF with bilateral pedicle screw and rod fixation. Minimally-invasive lateral interbody approaches are performed in the lateral decubitus position. Subsequent repositioning prone for bilateral pedicle screw and rod fixation requires significant time and resources and does not facilitate increased lumbar lordosis. The first 72 consecutive patients (300 screws) treated with single-position LLIF or OLLIF and bilateral pedicle screws by a single surgeon between December 2013 and August 2016 were included in the study. Screw accuracy and fusion were graded using CT and several timing parameters were recorded including retractor, fluoroscopy, and screw placement time. Complications including re-operation, infection, and post-operative radicular pain and weakness were recorded. Average screw placement time was 5.9 min/screw (stdev: 1.5 min.; range: 3-9.5 min). Average total operative time (interbody cage and pedicle screw placement) was 87.9 min. (stdev: 25.1 min.; range: 49-195 min) Average fluoroscopy time was 15.0 sec./screw (stdev: 4.7 sec.; range: 6-25 sec.). The pedicle screw breach rate was 5.1% with 10/13 breaches measured as screws with subsequent resolution of symptoms. The single-position, all-lateral technique was found to be feasible with accuracy, fluoroscopy usage and complication rates comparable to the published literature. This technique eliminates the time and staffing associated with intra-operative repositioning and may lead to significant improvements in operative efficiency and cost savings. 4.

  12. The role of imaging and in situ biomechanical testing in assessing pedicle screw pull-out strength.

    Science.gov (United States)

    Myers, B S; Belmont, P J; Richardson, W J; Yu, J R; Harper, K D; Nightingale, R W

    1996-09-01

    This study determined the predictive ability of quantitative computed tomography, dual energy x-ray absorptiometry, pedicular geometry, and mechanical testing in assessing the strength of pedicle screw fixation in an in vitro mechanical test of intra-pedicular screw fixation in the human cadaveric lumbar spine. To test several hypotheses regarding the relative predictive value of densitometry, pedicular geometry, and mechanical testing in describing pedicle screw pull-out. Previous investigations have suggested that mechanical testing, geometry, and densitometry, determined by quantitative computed tomography or dual energy x-ray absorptiometry, predict the strength of the screw-bone system. However, no study has compared the relative predictive value of these techniques. Forty-nine pedicle screw cyclic-combined flexion-extension moment-axial pull-out tests were performed on human cadaveric lumbar vertebrae. The predictive ability of quantitative computed tomography, dual energy x-ray absorptiometry, insertional torque, in situ stiffness, and pedicular geometry was assessed using multiple regression. Several variables correlated to force at failure. However, multiple regression analysis showed that bone mineral density of the pedicle determined by quantitative computed tomography, insertional torque, and in situ stiffness when used in combination resulted in the strongest prediction of pull-out force. No other measures provided additional predictive ability in the presence of these measures. Pedicle density determined by quantitative computed tomography when used with insertional torque and in situ stiffness provides the strongest predictive ability of screw pull-out. Geometric measures of the pedicle and density determined by dual energy x-ray absorptiometry do not provide additional predictive ability in the presence of these measures.

  13. Error rate of multi-level rapid prototyping trajectories for pedicle screw placement in lumbar and sacral spine

    Directory of Open Access Journals (Sweden)

    Merc Matjaz

    2014-10-01

    Full Text Available 【Abstract】Objective: Free-hand pedicle screw placement has a high incidence of pedicle perforation which can be reduced with fluoroscopy, navigation or an alternative rapid prototyping drill guide template. In our study the error rate of multi-level templates for pedicle screw placement in lumbar and sacral regions was evaluated. Methods: A case series study was performed on 11 patients. Seventy-two screws were implanted using multilevel drill guide templates manufactured with selective laser sintering. According to the optimal screw direction preoperatively defi ned, an analysis of screw misplacement was performed. Displacement, deviation and screw length difference were measured. The learning curve was also estimated. Results: Twelve screws (17% were placed more than 3.125 mm out of its optimal position in the centre of pedicle. The tip of the 16 screws (22% was misplaced more than 6.25 mm out of the predicted optimal position. According to our predefi ned goal, 19 screws (26% were implanted inaccurately. In 10 cases the screw length was selected incorrectly: 1 (1% screw was too long and 9 (13% were too short. No clinical signs of neurovascular lesion were observed. Learning curve was insignifi cantly noticeable (P=0.129. Conclusion: In our study, the procedure of manufacturing and applying multi-level drill guide templates has a 26% chance of screw misplacement. However, that rate does not coincide with pedicle perforation incidence and neurovascular injury. These facts along with a comparison to compatible studies make it possible to summarize that multi-level templates are satisfactorily accurate and allow precise screw placement with a clinically irrelevant mistake factor. Therefore templates could potentially represent a useful tool for routine pedicle screw placement. Key words: Drill guide; Template; Inaccuracy; Perforation; Radiation exposure

  14. Deviation analysis for C1/2 pedicle screw placement using a three-dimensional printed drilling guide.

    Science.gov (United States)

    Wu, Xinghuo; Liu, Rong; Yu, Jie; Lu, Lin; Yang, Cao; Shao, Zengwu; Ye, Zhewei

    2017-06-01

    Cervical transarticular fixation is a technically demanding procedure. This study aimed to develop a safer and more accurate method for C1/2 pedicle screw placement using a three-dimensional printed drilling guide. A total of 20 patients with C1/2 fractures and dislocations were recruited, and their computed tomography scans were evaluated. Under the assistance of the three-dimensional printed drilling guide, bilateral C1/2 pedicle screws were successfully placed in the three-dimensional C1/2 models. Then, sagittal and axial computed tomography scans were obtained, and the accuracy and safety of screw placement were evaluated based on X-Y-Z axis setup. The average depths for C1 and C2 pedicle screws were 30.1 ± 1.12 and 31.81 ± 0.85 mm on the left side and 29.54 ± 1.01 and 31.35 ± 0.27 mm on the right side, respectively. The average dimensional parameters for C1/C2 pedicle screw of both sides were measured and analyzed, which showed no statistically significant differences in the ideal and the actual entry points, inclined angles, and tailed angles. The method of developing a three-dimensional printed drilling guide is an easy and safe technique. This novel technique is applicable for C1/2 pedicle screw fixation; the potential use of the three-dimensional printed guide to place C1/2 pedicle screw is promising.

  15. Vascularized pedicle graft of ipsilateral fibula for recurrent congenital pseudoarthrosis of the tibia

    Directory of Open Access Journals (Sweden)

    Seyed Esmail Hassanpour

    2007-07-01

    Full Text Available

    We have performed the ipsilateral vascularized fibular transfer for the treatment of congenital pseudoarthrosis of the tibia (CPT. In the case under study, the conventional treatment by intramedullary rod and autogenous iliac bone grafting had failed. The follow up took place during the next 4 years and the patient can now walk without assistance. Combining a pedicle ipsilateral fibular transfer with an internal fixation and iliac bone graft may be a good option for the treatment of congenital pseudoarthrosis of tibia.
    KEY WORDS: Congenital pseudoarthrosis, tibia, vascularized fibular graft, bone graft.

  16. Pedicle Subtraction Osteotomy in a 5-Year-Old Child with Congenital Kyphosis

    Directory of Open Access Journals (Sweden)

    Farzad Omidi-Kashani

    2015-07-01

    Full Text Available Vertebral anomalies may also distort the normal regional or global spinal alignment and necessitate some therapeutic interventions. Hemiepiphysiodesis is a traditional procedure usually described for these young patients but in more severe cases some type of osteotomy seems to be necessary. In this technical note, we describe a 5-year-old boy with failed previous hemiepiphysiodesis surgery, who was successfully treated with one level pedicle subtraction osteotomy. This procedure not only corrects the kyphotic deformity at the time of the procedure (not relying on future spinal growth, but also avoids more hazardous anterior approach.

  17. Role of adipose-derived stromal cells in pedicle skin flap survival in experimental animal models

    Science.gov (United States)

    Foroglou, Pericles; Karathanasis, Vasileios; Demiri, Efterpi; Koliakos, George; Papadakis, Marios

    2016-01-01

    The use of skin flaps in reconstructive surgery is the first-line surgical treatment for the reconstruction of skin defects and is essentially considered the starting point of plastic surgery. Despite their excellent usability, their application includes general surgical risks or possible complications, the primary and most common is necrosis of the flap. To improve flap survival, researchers have used different methods, including the use of adipose-derived stem cells, with significant positive results. In our research we will report the use of adipose-derived stem cells in pedicle skin flap survival based on current literature on various experimental models in animals. PMID:27022440

  18. Management of Anterior Abdominal Wall Defect Using a Pedicled Tensor Fascia Lata Flap: A Case Report

    Directory of Open Access Journals (Sweden)

    K. D. Ojuka

    2012-01-01

    Full Text Available Degloving injuries to anterior abdominal wall are rare due to the mechanism of injury. Pedicled tensor fascia lata is known to be a versatile flap with ability to reach the lower anterior abdomen. A 34-year-old man who was involved in a road traffic accident presented with degloving injury and defect at the left inguinal region, sigmoid colon injury, and scrotal bruises. At investigation, he was found to have pelvic fracture. The management consisted of colostomy and tensor fascia lata to cover the defect at reversal. Though he developed burst abdomen on fifth postoperative day, the flap healed with no complications.

  19. The Effect of the Pedicle-Facet Angle on Degenerative Cervical Spondylolisthesis

    OpenAIRE

    Kim, Hyung Cheol; Jun, Hyo Sub; Kim, Ji Hee; Chang, In Bok; Song, Joon Ho; Oh, Jae Keun

    2015-01-01

    Objective To measure the orientation of the facet joints of cervical spine (C-spine) segments in the sagittal plane, known as the pedicle-facet (P-F) angle, and to use these measurements to evaluate the relationship between the P-F angle and the amount of vertebral anterolisthesis in patients with degenerative cervical spondylolisthesis (DCS). Methods A retrospective case-control study was performed including 30 age- and sex-matched patients with DCS and 30 control participants. Anterior-post...

  20. Modified sacrospinalis muscle pedicle bone graft for fusion of isthmic spondylolisthesis.

    Science.gov (United States)

    Adam, F F

    2001-01-01

    We treated 20 patients with symptomatic L4-5 isthmic spondylolisthesis (ten grade I, nine grade II and one grade III) surgically. All patients complained of low back pain and nine had additional radicular pain. Bilateral posterolateral fusion using the sacrospinalis muscle as a muscle pedicle bone graft was carried out in all patients. Decompression was added in patients with radiculopathy. Follow-up ranged from 12 to 28 months. Pain relief was graded as excellent in 18 patients, radiographic fusion as excellent in 17 patients and functional outcome as excellent in 19 patients.

  1. Methodology of Neural Design: Applications in Microwave Engineering

    OpenAIRE

    Z. Raida; P. Pomenka

    2006-01-01

    In the paper, an original methodology for the automatic creation of neural models of microwave structures is proposed and verified. Following the methodology, neural models of the prescribed accuracy are built within the minimum CPU time. Validity of the proposed methodology is verified by developing neural models of selected microwave structures. Functionality of neural models is verified in a design - a neural model is joined with a genetic algorithm to find a global minimum of a formulat...

  2. What are artificial neural networks?

    DEFF Research Database (Denmark)

    Krogh, Anders

    2008-01-01

    Artificial neural networks have been applied to problems ranging from speech recognition to prediction of protein secondary structure, classification of cancers and gene prediction. How do they work and what might they be good for? Udgivelsesdato: 2008-Feb......Artificial neural networks have been applied to problems ranging from speech recognition to prediction of protein secondary structure, classification of cancers and gene prediction. How do they work and what might they be good for? Udgivelsesdato: 2008-Feb...

  3. Application of the artificial neural network for reconstructing the internal-structure image of a random medium by spatial characteristics of backscattered optical radiation

    Science.gov (United States)

    Veksler, B. A.; Meglinskii, I. V.

    2008-06-01

    The feasibility of using an artificial neural network (ANN), which is the standard Matlab tool, for non-invasive (based on the data of backscattering) diagnostics of macro-inhomogeneities, localised at subsurface layers of the turbid strongly scattering medium was shown. The spatial and angle distribution of the backscattered optical radiation was calculated by using the Monte-Carlo method combining the modelling of effective optical paths and the use of statistical weights. It was shown that application of the backscattering method together with the ANN allows solving inverse problems for determining the average radius of the scattering particles and for reconstructing the images of structural elements within the medium with a high accuracy.

  4. Quantitative Structure-Activity Relationships of Noncompetitive Antagonists of the NMDA Receptor: A Study of a Series of MK801 Derivative Molecules Using Statistical Methods and Neural Network

    Directory of Open Access Journals (Sweden)

    T. Lakhlifi

    2003-04-01

    Full Text Available Abstract: From a series of 50 MK801 derivative molecules, a selected set of 44 compounds was submitted to a principal components analysis (PCA, a multiple regression analysis (MRA, and a neural network (NN. This study shows that the compounds' activity correlates reasonably well with the selected descriptors encoding the chemical structures. The correlation coefficients calculated by MRA and there after by NN, r = 0.986 and r = 0.974 respectively, are fairly good to evaluate a quantitative model, and to predict activity for MK801 derivatives. To test the performance of this model, the activities of the remained set of 6 compounds are deduced from the proposed quantitative model, by NN. This study proved that the predictive power of this model is relevant.

  5. Optimizing finite element predictions of local subchondral bone structural stiffness using neural network-derived density-modulus relationships for proximal tibial subchondral cortical and trabecular bone.

    Science.gov (United States)

    Nazemi, S Majid; Amini, Morteza; Kontulainen, Saija A; Milner, Jaques S; Holdsworth, David W; Masri, Bassam A; Wilson, David R; Johnston, James D

    2017-01-01

    Quantitative computed tomography based subject-specific finite element modeling has potential to clarify the role of subchondral bone alterations in knee osteoarthritis initiation, progression, and pain. However, it is unclear what density-modulus equation(s) should be applied with subchondral cortical and subchondral trabecular bone when constructing finite element models of the tibia. Using a novel approach applying neural networks, optimization, and back-calculation against in situ experimental testing results, the objective of this study was to identify subchondral-specific equations that optimized finite element predictions of local structural stiffness at the proximal tibial subchondral surface. Thirteen proximal tibial compartments were imaged via quantitative computed tomography. Imaged bone mineral density was converted to elastic moduli using multiple density-modulus equations (93 total variations) then mapped to corresponding finite element models. For each variation, root mean squared error was calculated between finite element prediction and in situ measured stiffness at 47 indentation sites. Resulting errors were used to train an artificial neural network, which provided an unlimited number of model variations, with corresponding error, for predicting stiffness at the subchondral bone surface. Nelder-Mead optimization was used to identify optimum density-modulus equations for predicting stiffness. Finite element modeling predicted 81% of experimental stiffness variance (with 10.5% error) using optimized equations for subchondral cortical and trabecular bone differentiated with a 0.5g/cm(3) density. In comparison with published density-modulus relationships, optimized equations offered improved predictions of local subchondral structural stiffness. Further research is needed with anisotropy inclusion, a smaller voxel size and de-blurring algorithms to improve predictions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Anterior Dual Rod Versus Posterior Pedicle Fixation Surgery for the Surgical Treatment in Lenke 5C Adolescent Idiopathic Scoliosis: A Multicenter, Matched Case Analysis of 42 Patients.

    Science.gov (United States)

    Geck, Matthew J; Rinella, Anthony; Hawthorne, Dana; Macagno, Angel; Koester, Linda; Sides, Brenda; Lenke, Lawrence; Bridwell, Keith; O'Brien, Mike; Shufflebarger, Harry L

    2013-05-01

    Multicenter matched case analysis. Compare patients with Lenke 5C scoliosis surgically treated with anterior spinal fusion with dual rod instrumentation and anterior column support versus posterior release and pedicle screw instrumentation. Treatment of single, structural, lumbar and thoracolumbar curves in patients with adolescent idiopathic scoliosis (AIS) has been the subject of some debate. Previous papers directly comparing these approaches are problematic because of heterogeneity of the groups, nonrandomized protocols, and surgeon bias and variation of instrumentation (upper instrumented vertebrae and lower instrumented vertebrae) in relation to the defined Cobb angle (upper end vertebra and lower end vertebrae). This report sought to remedy these flaws by analyzing a database of Lenke 5C AIS and performing matched cases. We analyzed 96 patients with Lenke 5C AIS curves based on radiographic and clinical data at 3 institutions, surgically treated between 2001 and 2005 with minimum 2-year follow-up. Case matched criteria (age within 1 year, sex, curve within 5°, lower end vertebrae, and lower instrumented vertebrae) yielded 21 matched patient pairs. We evaluated and compared multiple clinical and radiographic parameters. We observed no significant statistical differences between groups in any preoperative clinical or radiographic parameters. At final follow-up, the major curve measured 8° (83%) in the posterior spinal fusion group, compared with 13° (72%) in the anterior spinal fusion group (p = .002). Estimated blood loss was similar in both groups. Hospital stay was significantly shorter in the posterior spinal fusion group. There were no differences in radiographic complications, such as proximal junctional kyphosis. At a minimum of 2 years' follow-up in a multicenter, matched case analysis, adolescents with Lenke 5C curves demonstrated statistically significantly better curve correction and shorter hospital stays when treated with a posterior release

  7. Designs and Techniques That Improve the Pullout Strength of Pedicle Screws in Osteoporotic Vertebrae: Current Status

    Directory of Open Access Journals (Sweden)

    Thomas M. Shea

    2014-01-01

    Full Text Available Osteoporosis is a medical condition affecting men and women of different age groups and populations. The compromised bone quality caused by this disease represents an important challenge when a surgical procedure (e.g., spinal fusion is needed after failure of conservative treatments. Different pedicle screw designs and instrumentation techniques have been explored to enhance spinal device fixation in bone of compromised quality. These include alterations of screw thread design, optimization of pilot hole size for non-self-tapping screws, modification of the implant’s trajectory, and bone cement augmentation. While the true benefits and limitations of any procedure may not be realized until they are observed in a clinical setting, axial pullout tests, due in large part to their reproducibility and ease of execution, are commonly used to estimate the device’s effectiveness by quantifying the change in force required to remove the screw from the body. The objective of this investigation is to provide an overview of the different pedicle screw designs and the associated surgical techniques either currently utilized or proposed to improve pullout strength in osteoporotic patients. Mechanical comparisons as well as potential advantages and disadvantages of each consideration are provided herein.

  8. Closing a Tracheal Defect with an Omental Pedicled Gastric Flap; A Technical Note

    Science.gov (United States)

    Rupprecht, Holger; Ghidau, Marius; Gaab, Katharina

    2017-01-01

    Due to an adenocarcinoma of the right upper lobe with infiltration of the main bronchus a 49-years-old female patient underwent an upper bilobectomy with sleeve resection. After two completed chemotherapy bouts and signs of sepsis another thoracotomy was inevitable.  As a complicating factor a supracarinal, necrotic and perforating lesion of the trachea appeared. The defect can be initially repaired with a suture and covered with azygos vein material. However surgical revision showed an enlargement of the tracheal necrosis. Then the lesion was occluded with a diaphragmatic pedicled flap. Nevertheless after the operation a tracheal insufficiency with massive ventilation leakage was observed. It was generated by the death of the diaphragmatic flap. As an ultimate therapeutic measure a transplantation of a pedicled omental gastric flap was performed, which in case of a failure of the conventional operative techniques, is an additional option in closing tracheal defects caused by infections. Especially in cases of massive infected thoracic cavity and tracheal necrosis omentum majus is, compared to muscle flaps, the better biological tissue to close and heal the tracheal defect. This case report firstly describes a successfully closure of a tracheal defect using the technique mentioned above. PMID:28508001

  9. Teriparatide increases the insertional torque of pedicle screws during fusion surgery in patients with postmenopausal osteoporosis.

    Science.gov (United States)

    Inoue, Gen; Ueno, Masaki; Nakazawa, Toshiyuki; Imura, Takayuki; Saito, Wataru; Uchida, Kentaro; Ohtori, Seiji; Toyone, Tomoaki; Takahira, Naonobu; Takaso, Masashi

    2014-09-01

    The object of this study was to examine the efficacy of preoperative teriparatide treatment for increasing the insertional torque of pedicle screws during fusion surgery in postmenopausal women with osteoporosis. Fusion surgery for the thoracic and/or lumbar spine was performed in 29 postmenopausal women with osteoporosis aged 65-82 years (mean 72.2 years). The patients were divided into 2 groups based on whether they were treated with teriparatide (n = 13) or not (n = 16) before the surgery. In the teriparatide-treated group, patients received preoperative teriparatide therapy as either a daily (20 μg/day, n = 7) or a weekly (56.5 μg/week, n = 6) injection for a mean of 61.4 days and a minimum of 31 days. During surgery, the insertional torque was measured in 212 screws inserted from T-7 to L-5 and compared between the 2 groups. The correlation between the insertional torque and the duration of preoperative teriparatide treatment was also investigated. The mean insertional torque value in the teriparatide group was 1.28 ± 0.42 Nm, which was significantly higher than in the control group (1.08 ± 0.52 Nm, p osteoporosis. Preoperative teriparatide treatment might be an option for maximizing the purchase of the pedicle screws to the bone at the time of fusion surgery.

  10. Autologous reconstruction of the inguinal ligament using pedicled fascia lata flap: A new technique.

    Science.gov (United States)

    Bott, Alasdair R; Chummun, Shaheel; Rickard, Rory F; Kingsnorth, Andrew N

    2013-01-01

    A technique of reconstructing the inguinal ligament using a pedicled fascia lata flap is described. A 62-year-old man was referred with massive bilateral abdominal wall hernias, following numerous attempts at repair and subsequent recurrences. There was complete absence of the right inguinal ligament. The inguinal ligament was reconstructed using a strip of fascia lata, pedicled on the anterior superior iliac spine. This was transposed to cover the external iliac vessels, and sutured to the pubic tubercle. The musculoaponeurotic abdominal wall was reconstructed with two 20cm×20cm sheets of porcine acellular dermal matrix and an overlying sheet of polypropylene mesh, sutured to the remaining abdominal wall muscles laterally, and to both inguinal ligaments. The cutaneous abdominal wall was closed with an abdominoplasty technique. The reconstruction has remained intact nine months following surgery. Complete destruction of the inguinal ligament is rare but can occur following multiple operative procedures or trauma. To date, the only published reports of inguinal ligament reconstruction have been performed using synthetic mesh. The use of autologous tissue should reduce the risk of erosion into the neurovascular bundle, seroma formation, and enhance integration into surrounding tissues. This new technique for autologous reconstruction of the inguinal ligament provides a safe alternative to the use of synthetic mesh in the operative armamentarium of plastic and hernia surgeons. Copyright © 2013 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

  11. Sacrospinalis muscle-pedicle bone graft in posterolateral fusion for spondylolisthesis.

    Science.gov (United States)

    Baksi, D P

    1998-01-01

    Twenty three patients with lumbar spondylolisthesis (6 Grade I, 14 Grade II and 3 Grade III) with low back pain, and radicular pain in 14, were treated surgically when they failed to respond to conservative treatment. Their average age was 33.2 years. Bilateral posterolateral spinal fusions with autologous iliac bone chips, supplemented by a sacrospinalis muscle-pedicle bone graft on the left side, were undertaken after laminectomy and foraminotomy in all except in two adolescents, where laminectomy and foraminotomy were avoided. The period of follow-up varied from 26 to 126 months (average 65.3 months). The results in 11 (48%) patients were excellent, 9 (39%) were good, 2 (9%) fair and one (4%) poor. There was a higher incidence (87%) of good quality of osseous fusion on the left side, where the sacrospinalis muscle-pedicle bone graft was used, compared to the right, where 70% of fusions were satisfactory. Function improved in 91% of the patients. Neither scoliosis nor weakness of the extensor muscles of the back developed due to reanchorage of the sacrospinalis muscle to the lumbosacral spines.

  12. Through-and-through Nasal Reconstruction with the Bi-Pedicled Forehead Flap

    Directory of Open Access Journals (Sweden)

    Tommaso Agostini

    2013-11-01

    Full Text Available BackgroundNasal reconstruction is one of the most difficult challenges for the head and neck surgeon, especially in the case of complex full thickness defects following malignant skin tumor resection. Full-thickness defects require demanding multi-step reconstruction.MethodsSeven patients underwent surgical reconstruction of full-thickness nasal defects with a bi-pedicled forehead flap shaped appropriately to the defect. Patients were aged between 58 and 86 years, with a mean age of 63.4 years. All of the tumors were excised using traditional surgery, and in 4 of the patients, reconstruction was performed simultaneously following negativity of fresh frozen sections of the margins under general anesthesia.ResultsNasal reconstruction was well accepted by all of the patients suffering non-melanoma skin tumors with acceptable cosmetic outcomes. The heart-shaped forehead flap was harvested in cases of subtotal involvement of the nasal pyramid, while smaller defects were reconstructed with a wing-shaped flap. No cartilaginous or osseous support was necessary.ConclusionsThis bi-pedicled forehead flap was a valid, versatile, and easy-to-implement alternative to microsurgery or multi-step reconstruction. The flap is the best indication for full-thickness nasal defects but can also be indicated for other complex facial defects in the orbital (exenteratio orbitae, zygomatic, and cheek area, for which the availability of a flap equipped with two thick and hairless lobes can be a valuable resource.

  13. C2 pars/pedicle screws in management of craniocervical and upper cervical instability.

    Science.gov (United States)

    Eshra, Mohammed Ahmed

    2014-04-01

    A retrospective study. To evaluate the efficacy and the safety of craniocervical and upper cervical stabilization by using C2 pars/pedicle screw fixations. The management of craniocervical and upper cervical instability has progressed over the past two decades due to good achievements in the instrumentation and the increased awareness on spinal anatomy and biomechanics. However, there is insufficient studies or solid conclusions on this topic, thus, we tried to investigate and present our findings. Twenty-two patients were operated upon and were followed up from March 2008 to October 2010. One patient had craniocervical instability (post-surgical), 15 patients had atlantoaxial instability of different etiologies (trauma, tumors, inflammatory and degenerative) and 6 patients had hangman fractures. Patients' ages ranged from 18 to 52 years old. with 5 female patients and 17 male patients. Radiological follow ups performed immediately post-operation showed good screw positioning and complete reductions in nearly all the cases. All patients were followed up for more than one year. Sound fusions were observed among all patients. The use of pars/pedicle screws is a very effective, sound, safe and easy surgical modality for treating craniocervical, atlantoaxial and upper cervical instabilities. Increasing studies for the biomechanics of this important region and longer periods of follow-ups are necessary to document the usefulness of this modality when treating such patients.

  14. The Neural Correlates of Race

    Science.gov (United States)

    Ito, Tiffany A.; Bartholow, Bruce D.

    2009-01-01

    Behavioral analyses are a natural choice for understanding the wide-ranging behavioral consequences of racial stereotyping and prejudice. However, neuroimaging and electrophysiological research has recently considered the neural mechanisms that underlie racial categorization and the activation and application of racial stereotypes and prejudice, revealing exciting new insights. Work reviewed here points to the importance of neural structures previously associated with face processing, semantic knowledge activation, evaluation, and self-regulatory behavioral control, allowing for the specification of a neural model of race processing. We show how research on the neural correlates of race can serve to link otherwise disparate lines of evidence on the neural underpinnings of a broad array of social-cognitive phenomena, and consider implications for effecting change in race relations. PMID:19896410

  15. Neural-like growing networks

    Science.gov (United States)

    Yashchenko, Vitaliy A.

    2000-03-01

    On the basis of the analysis of scientific ideas reflecting the law in the structure and functioning the biological structures of a brain, and analysis and synthesis of knowledge, developed by various directions in Computer Science, also there were developed the bases of the theory of a new class neural-like growing networks, not having the analogue in world practice. In a base of neural-like growing networks the synthesis of knowledge developed by classical theories - semantic and neural of networks is. The first of them enable to form sense, as objects and connections between them in accordance with construction of the network. With thus each sense gets a separate a component of a network as top, connected to other tops. In common it quite corresponds to structure reflected in a brain, where each obvious concept is presented by certain structure and has designating symbol. Secondly, this network gets increased semantic clearness at the expense owing to formation not only connections between neural by elements, but also themselves of elements as such, i.e. here has a place not simply construction of a network by accommodation sense structures in environment neural of elements, and purely creation of most this environment, as of an equivalent of environment of memory. Thus neural-like growing networks are represented by the convenient apparatus for modeling of mechanisms of teleological thinking, as a fulfillment of certain psychophysiological of functions.

  16. Application of electrical capacitance tomography and artificial neural networks to rapid estimation of cylindrical shape parameters of industrial flow structure

    Directory of Open Access Journals (Sweden)

    Garbaa Hela

    2016-12-01

    Full Text Available A new approach to solve the inverse problem in electrical capacitance tomography is presented. The proposed method is based on an artificial neural network to estimate three different parameters of a circular object present inside a pipeline, i.e. radius and 2D position coordinates. This information allows the estimation of the distribution of material inside a pipe and determination of the characteristic parameters of a range of flows, which are characterised by a circular objects emerging within a cross section such as funnel flow in a silo gravitational discharging process. The main advantages of the proposed approach are explicitly: the desired characteristic flow parameters are estimated directly from the measured capacitances and rapidity, which in turn is crucial for online flow monitoring. In a classic approach in order to obtain these parameters in the first step the image is reconstructed and then the parameters are estimated with the use of image processing methods. The obtained results showed significant reduction of computations time in comparison to the iterative LBP or Levenberg-Marquard algorithms.

  17. Functionality Evaluation of a Novel Smart Expandable Pedicle Screw to Mitigate Osteoporosis Effect in Bone Fixation: Modeling and Experimentation

    Directory of Open Access Journals (Sweden)

    Ahmadreza Eshghinejad

    2013-01-01

    Full Text Available This paper proposes a novel expandable-retractable pedicle screw and analyzes its functionality. A specially designed pedicle screw is described which has the ability to expand and retract using nitinol elements. The screw is designed to expand in body temperature and retract by cooling the screw. This expansion-retraction function is verified in an experiment designed in larger scale using a nitinol antagonistic assembly. The results of this experiment are compared to the results of a finite element model developed in Abaqus in combination with a user material subroutine (UMAT. This code has been developed to analyze the nonlinear thermomechanical behavior of shape memory alloy materials. The functionality of the proposed screw is evaluated with simulation and experimentation in a pullout test as well. The pullout force of a normal screw inserted in a normal bone was simulated, and the result is compared with the results of the expandable screw in osteoporotic bone. Lastly, strength of the designed pedicle screw in a foam block is also verified with experiment. The reported finite element simulations and experiments are the proof for the concept of nitinol expandable-retractable elements on a pedicle screw which validate the functionality in a pullout test.

  18. Minimally Invasive Pedicle Screw Placement in A Case of L4 Fracture: Case Report with Review of Literature

    Science.gov (United States)

    Agrawal, Abhishek; Mizuno, Junichi; Kato, Yoko; Inoue, Tatsushi; Sano, Hirotoshi

    2010-01-01

    Introduction: Pedicle screw instrumentation provides a rigid construct to promote fusion in cases of spinal trauma and degenerative diseases. Minimally invasive percutaneous technique in lumbar spine is a safe and reliable procedure as compared to the well established Magerl technique. It is a straight forward alternative to open approaches or minimally invasive ones and the accuracy of screw placement is also similar to that reported for other techniques. Case Report: A 16 year old high school boy presented to us with accidental fall from third floor. He was suffering from common cold with resulting high fever. He developed low back ache with bilateral radiculopathy and weakness of dorsiflexors. Neuro-imaging revealed a burst fracture of L4 vertebral body (type A 3.3 according to Magerl/AO spine classification), with bone fragments compromising the spinal canal. Delayed surgery was planned in view of anticipated excessive bleeding from the wound site in addition to poor general condition. Using a bone impactor, the bony fragments were impacted back into the original vertebral body space. Sextant (Medtronic Sofamor Danek, Tennessee, USA) percutaneous pedicle screw and rod fixation device was then used as a rigid construct to stabilize the lumbar spine. Post-operative CT scan and MRI revealed accurate pedicle screw fixation with adequately decompressed spinal canal. Conclusion: Short segment fusion with minimally invasive pedicle screwing following decompression of cauda equina was considered to be a minimally invasive approach for this case. PMID:22028760

  19. A novel injectable calcium phosphate-based nanocomposite for the augmentation of cannulated pedicle-screw fixation

    Science.gov (United States)

    Sun, Haolin; Liu, Chun; Liu, Huiling; Bai, Yanjie; Zhang, Zheng; Li, Xuwen; Li, Chunde; Yang, Huilin; Yang, Lei

    2017-01-01

    Polymethyl methacrylate (PMMA)-augmented cannulated pedicle-screw fixation has been routinely performed for the surgical treatment of lumbar degenerative diseases. Despite its satisfactory clinical outcomes and prevalence, problems and complications associated with high-strength, stiff, and nondegradable PMMA have largely hindered the long-term efficacy and safety of pedicle-screw fixation in osteoporotic patients. To meet the unmet need for better bone cement for cannulated pedicle-screw fixation, a new injectable and biodegradable nanocomposite that was the first of its kind was designed and developed in the present study. The calcium phosphate-based nanocomposite (CPN) exhibited better anti-pullout ability and similar fluidity and dispersing ability compared to clinically used PMMA, and outperformed conventional calcium phosphate cement (CPC) in all types of mechanical properties, injectability, and biodegradability. In term of axial pullout strength, the CPN-augmented cannulated screw reached the highest force of ~120 N, which was higher than that of PMMA (~100 N) and CPC (~95 N). The compressive strength of the CPN (50 MPa) was three times that of CPC, and the injectability of the CPN reached 95%. In vivo tests on rat femur revealed explicit biodegradation of the CPN and subsequent bone ingrowth after 8 weeks. The promising results for the CPN clearly suggest its potential for replacing PMMA in the application of cannulated pedicle-screw fixation and its worth of further study and development for clinical uses. PMID:28490878

  20. Use of next generation sequencing to detect biofilm bacteria in a patient with pedicle screw loosening after spine surgery

    DEFF Research Database (Denmark)

    Xu, Yijuan; Thomsen, Trine Rolighed; Lorenzen, Jan

    2016-01-01

    . However, long-term cultures detected Propionibacterium acnes. Molecular analysis revealed presence of Corynebacterium species. The patient received oral clindamycine 600 mg 3 times/day for 6 weeks; 10 months later he had no problems from the lumbar spine. Follow-up CT scan showed no recurrence of pedicle...

  1. Minimally invasive pedicle screw placement in a case of L4 fracture: case report with review of literature.

    Science.gov (United States)

    Agrawal, Abhishek; Mizuno, Junichi; Kato, Yoko; Inoue, Tatsushi; Sano, Hirotoshi

    2010-07-01

    Pedicle screw instrumentation provides a rigid construct to promote fusion in cases of spinal trauma and degenerative diseases. Minimally invasive percutaneous technique in lumbar spine is a safe and reliable procedure as compared to the well established Magerl technique. It is a straight forward alternative to open approaches or minimally invasive ones and the accuracy of screw placement is also similar to that reported for other techniques. A 16 year old high school boy presented to us with accidental fall from third floor. He was suffering from common cold with resulting high fever. He developed low back ache with bilateral radiculopathy and weakness of dorsiflexors. Neuro-imaging revealed a burst fracture of L4 vertebral body (type A 3.3 according to Magerl/AO spine classification), with bone fragments compromising the spinal canal. Delayed surgery was planned in view of anticipated excessive bleeding from the wound site in addition to poor general condition. Using a bone impactor, the bony fragments were impacted back into the original vertebral body space. Sextant (Medtronic Sofamor Danek, Tennessee, USA) percutaneous pedicle screw and rod fixation device was then used as a rigid construct to stabilize the lumbar spine. Post-operative CT scan and MRI revealed accurate pedicle screw fixation with adequately decompressed spinal canal. Short segment fusion with minimally invasive pedicle screwing following decompression of cauda equina was considered to be a minimally invasive approach for this case.

  2. Percutaneous pedicle screw reduction and axial presacral lumbar interbody fusion for treatment of lumbosacral spondylolisthesis: A case series

    OpenAIRE

    Miller Larry E; Tender Gabriel C; Block Jon E

    2011-01-01

    Abstract Introduction Traditional surgical management of lumbosacral spondylolisthesis is technically challenging and is associated with significant complications. The advent of minimally invasive surgical techniques offers patients treatment alternatives with lower operative morbidity risk. The combination of percutaneous pedicle screw reduction and an axial presacral approach for lumbosacral discectomy and fusion offers an alternative procedure for the surgical management of low-grade lumbo...

  3. Accuracy of robot-guided versus freehand fluoroscopy-assisted pedicle screw insertion in thoracolumbar spinal surgery.

    Science.gov (United States)

    Molliqaj, Granit; Schatlo, Bawarjan; Alaid, Awad; Solomiichuk, Volodymyr; Rohde, Veit; Schaller, Karl; Tessitore, Enrico

    2017-05-01

    OBJECTIVE The quest to improve the safety and accuracy and decrease the invasiveness of pedicle screw placement in spine surgery has led to a markedly increased interest in robotic technology. The SpineAssist from Mazor is one of the most widely distributed robotic systems. The aim of this study was to compare the accuracy of robot-guided and conventional freehand fluoroscopy-guided pedicle screw placement in thoracolumbar surgery. METHODS This study is a retrospective series of 169 patients (83 women [49%]) who underwent placement of pedicle screw instrumentation from 2007 to 2015 in 2 reference centers. Pathological entities included degenerative disorders, tumors, and traumatic cases. In the robot-assisted cohort (98 patients, 439 screws), pedicle screws were inserted with robotic assistance. In the freehand fluoroscopy-guided cohort (71 patients, 441 screws), screws were inserted using anatomical landmarks and lateral fluoroscopic guidance. Patients treated before 2009 were included in the fluoroscopy cohort, whereas those treated since mid-2009 (when the robot was acquired) were included in the robot cohort. Since then, the decision to operate using robotic assistance or conventional freehand technique has been based on surgeon preference and logistics. The accuracy of screw placement was assessed based on the Gertzbein-Robbins scale by a neuroradiologist blinded to treatment group. The radiological slice with the largest visible deviation from the pedicle was chosen for grading. A pedicle breach of 2 mm or less was deemed acceptable (Grades A and B) while deviations greater than 2 mm (Grades C, D, and E) were classified as misplacements. RESULTS In the robot-assisted cohort, a perfect trajectory (Grade A) was observed for 366 screws (83.4%). The remaining screws were Grades B (n = 44 [10%]), C (n = 15 [3.4%]), D (n = 8 [1.8%]), and E (n = 6 [1.4%]). In the fluoroscopy-guided group, a completely intrapedicular course graded as A was found in 76% (n = 335). The

  4. Augmentation of pedicle screw fixation strength using an injectable calcium phosphate cement as a function of injection timing and method.

    Science.gov (United States)

    Renner, Susan M; Lim, Tae-Hong; Kim, Whoan-Jeang; Katolik, Leonid; An, Howard S; Andersson, Gunnar B J

    2004-06-01

    Axial pullout tests using fresh cadaveric thoracolumbar vertebral bodies. To evaluate the effect of a new injectable calcium phosphate cement on the axial pullout strength of both revised and augmented pedicle screws in comparison with polymethyl methacrylate and in terms of injection method. Failure of pedicle screws by loosening and back out remains a significant clinical problem and is of particular concern for patients with low bone quality. Polymethyl methacrylate was shown to significantly improve the screw pullout strength. However, polymethyl methacrylate is known to have a high polymerization temperature, which may damage surrounding tissues, and a short handling time, and it lacks long-term biocompatibility. Bone mineral cements such as calcium phosphate have a longer working time, very low thermal effect, and are biodegradable as well as having good mechanical strength. Recently, new calcium phosphate cement with improved infiltration properties for better injectability has been introduced, but its performance in augmenting the pedicle screw fixation has not been tested yet. The bone mineral densities of 52 vertebral bodies (T11-L5) were measured using dual-energy x-ray absorptiometry. In each vertebral body, a 6.5-mm-diameter and 45 +/- 5-mm-long pedicle screw was inserted into either the right or left pedicle, representing an initial intact implantation. These intact screws were pulled axially until failure at 10 mm/min. Following failure of the intact pedicle, 3.0 cc of cement was injected into the failed screw hole, representing a revision case, and the prepared screw hole in the contralateral intact pedicle representing an augmentation case. The cement was injected either to the distal tip of the screw hole (calcium phosphate-1 group, n = 19) or along the entire length of the screw hole (calcium phosphate-2 group, n = 20), and the screws were inserted. The cement was then allowed to cure for 24 hours at room temperature before both screws were

  5. Clinical Comparison of Full and Partial Double Pedicle Flaps with Connective Tissue Grafts for Treatment of Gingival Recession.

    Science.gov (United States)

    Ranjbari, Ardeshir; Gholami, Gholam Ali; Amid, Reza; Kadkhodazadeh, Mahdi; Youssefi, Navid; Mehdizadeh, Amir Reza; Aghaloo, Maryam

    2016-09-01

    Gingival recession has been considered as the most challenging issue in the field of periodontal plastic surgery. The purpose of this study was to evaluate the clinical efficacy of root coverage procedures by using partial thickness double pedicle graft and compare it with full thickness double pedicle graft. Eight patients, aged 15 to 58 years including 6 females and 2 males with 20 paired (mirror image) defects with class I and II gingival recession were randomly assigned into two groups. Clinical parameters such as recession depth, recession width, clinical attachment level, probing depth, and width of keratinized tissue were measured at the baseline and 6 months post-surgery. A mucosal double papillary flap was elevated and the respective root was thoroughly planed. The connective tissue graft was harvested from the palate, and then adapted over the root. The pedicle flap was secured over the connective tissue graft and sutured. The surgical technique was similar in the control group except for the prepared double pedicle graft which was full thickness. The mean root coverage was 88.14% (2.83 mm) in the test group and 85.7% (2.75 mm) in the control group. No statistical differences were found in the mean reduction of vertical recession, width of recession, or probing depth between the test and control groups. In both procedures, the width of keratinized tissue increased after three months and the difference between the two groups was not statistically significant in this respect. Connective tissue with partial and full thickness double pedicle grafts can be successfully used for treatment of marginal gingival recession.

  6. Risk Factors for Pedicle Flap Complications in 251 Elderly Chinese Patients Who Underwent Oral and Maxillofacial Reconstruction.

    Science.gov (United States)

    Fang, Zao; Tian, Zhuowei; Zhang, Chenping; Sun, Jian; Hu, Jingzhou; He, Yue

    2016-10-01

    To determine risk factors for pedicle flap complications in elderly patients undergoing oral and maxillofacial reconstruction. The authors designed and implemented a retrospective cohort study and enrolled a sample of patients at least 75 years old who underwent resection of oral and maxillofacial tumors and pedicle flap reconstruction from January 2004 through December 2013. The primary predictor variable was reconstructive technique grouped into 5 types of pedicle flap. The difference among groups was tested with the χ(2) test and t test. The primary outcome variable was the presence of flap complication, which was divided into minor and major groups. Other variables were grouped into the following sets: demographic, operative, and adjuvant treatments. Univariate, bivariate, and regression statistics were computed and statistical significance was set at a P value less than .05. The study sample was composed of 251 patients with a mean age of 78 years and 62.95% were men. Of these, 68.13% had various preoperative systemic diseases. With regard to flap type, 120 underwent reconstruction with a pectoralis major myocutaneous flap, 5 with a submental island flap, 4 with a submandibular gland flap, 13 with a platysma myocutaneous flap, and 109 with a sternocleidomastoid flap. TNM stage (negative correlation) and smoking (positive correlation) correlated with flap type. There were 48 complications, of which 32 were minor and 16 were major; flap failure was observed in only 1 patient. Risk factors associated with complications were types of pedicle flap, age, heart score, hypertension, diabetes, postoperative hypoproteinemia, and drug-induced liver injury. The pedicle flap is suitable and safe for the reconstruction of defects caused by the ablation of oral and maxillofacial tumors in elderly patients. Preoperative evaluation of positive risk factors, including type of surgery and systemic conditions, is very important for the selection of an appropriate flap for such

  7. A pedicle subtraction osteotomy as an adjunctive tool in the surgical treatment of a rigid thoracolumbar hyperkyphosis; a preliminary report.

    Science.gov (United States)

    van Loon, Piet J M; van Stralen, Gijs; van Loon, Corne J M; van Susante, Job L C

    2006-01-01

    A pedicle subtraction osteotomy can be considered as part of the surgical treatment of a symptomatic sagittal imbalance. The literature on the use of this technique is limited and thus far not applied to a rigid thoracolumbar hyperkyphosis. To evaluate our preliminary results of a pedicle subtraction osteotomy as an adjunctive tool in the surgical treatment of thoracolumbar kyphotic deformities. Case series Eleven patients with a symptomatic kyphotic deformity were treated with a thoracolumbar pedicle subtraction osteotomy in combination with a multilevel correction. The mean follow-up was 42.8 months (range 26-105). The clinical outcome, radiographic correction, and perioperative complications were analyzed. The results in six more traditional indications (ankylosing spondylitis, kyphoscoliosis, congenital and posttraumatic deformity), were compared with the results in a subgroup of five cases with a rigid thoracolumbar hyperkyphosis. All patients had a kyphotic thoracolumbar junction. An average of 5.8 levels was involved in the corrective fusion. A pedicle subtraction was always performed between the level Th10 and L2 to correct the sagittal balance. A lordotic correction of 38.8 (range 25-49) degrees was established with this fusion. The osteotomy contributed 66% (26.9 degrees) of the correction, whereas the remaining correction came from multilevel facetectomies. The visual analogue scale for both pain and impairment improved significantly (p<.005) for the entire group. Statistical analysis on the results for both subgroups separately was inappropriate because of the small number of patients available; however, overall both subgroups appeared to do equally well. All patients were very satisfied with the result and would choose surgical treatment again. No major complications were encountered. A pedicle subtraction osteotomy is a technically demanding but well tolerated operative procedure for the correction of a kyphotic deformity. This technique can also be

  8. Neural network approach to parton distributions fitting

    CERN Document Server

    Piccione, Andrea; Forte, Stefano; Latorre, Jose I.; Rojo, Joan; Piccione, Andrea; Rojo, Joan

    2006-01-01

    We will show an application of neural networks to extract information on the structure of hadrons. A Monte Carlo over experimental data is performed to correctly reproduce data errors and correlations. A neural network is then trained on each Monte Carlo replica via a genetic algorithm. Results on the proton and deuteron structure functions, and on the nonsinglet parton distribution will be shown.

  9. Neural Networks for Non-linear Control

    DEFF Research Database (Denmark)

    Sørensen, O.

    1994-01-01

    This paper describes how a neural network, structured as a Multi Layer Perceptron, is trained to predict, simulate and control a non-linear process.......This paper describes how a neural network, structured as a Multi Layer Perceptron, is trained to predict, simulate and control a non-linear process....

  10. A Fuzzy Neural Tree for Possibilistic Reliability

    NARCIS (Netherlands)

    Ciftcioglu, O.

    2008-01-01

    An innovative neural fuzzy system is considered for possibilistic reliability using a neural tree structure with nodes of neuronal type. The total tree structure works effectively as a fuzzy logic system where the possibility theory plays important role with Gaussian possibility distribution at the

  11. Intraosseous Injection of Simvastatin in Poloxamer 407 Hydrogel Improves Pedicle-Screw Fixation in Ovariectomized Minipigs.

    Science.gov (United States)

    Fu, X; Tan, J; Sun, C G; Leng, H J; Xu, Y S; Song, C L

    2016-11-16

    Osteoporosis leads to poor osseointegration and reduces implant stability. Statins have been found to stimulate bone formation, but the bioavailability from oral administration is low. Local application may be more effective at augmenting bone formation and enhancing implant stability. This study was performed to evaluate the efficacy of an intraosseous injection of simvastatin in thermosensitive poloxamer 407 hydrogel to enhance pedicle-screw fixation in calcium-restricted ovariectomized minipigs. Nine mature female Guangxi Bama minipigs underwent bilateral ovariectomy and were fed a calcium-restricted diet for 18 months. Simvastatin (0, 0.5, or 1 mg) in thermosensitive poloxamer 407 hydrogel was injected into the lumbar vertebrae (L4-L6), and titanium alloy pedicle screws were implanted. Bone mineral density (BMD) measurements of the lumbar vertebrae were determined by dual x-ray absorptiometry (DXA) before and 3 months after treatment. The lumbar vertebrae were harvested and analyzed with use of microcomputed tomography, biomechanical pull-out testing, histological analysis, and Western blot analysis for bone morphogenetic protein (BMP)-2 and vascular endothelial growth factor (VEGF) expression. Evaluation over a 3-month study period demonstrated that the BMD of the vertebrae injected with 0.5 and 1.0 mg of simvastatin had increased by 31.25% and 31.09%, respectively, compared with vehicle-only injection (p ≤ 0.00014 for both) and increased by 32.12% and 28.16%, respectively, compared with the pre-treatment levels (p simvastatin in poloxamer 407 increased trabecular volume fraction, thickness, and number and decreased trabecular separation (p ≤ 0.002). The bone formation and mineral apposition rates significantly increased (p ≤ 0.023). The percentage of osseointegration in the simvastatin 0.5 and 1-mg groups was 46.54% and 42.63% greater, respectively, than that in the vehicle-only group (p ≤ 0.006), and the maximum pull-out strength was 45.75% and 51

  12. Thumb Tip Defect Reconstruction Using Neurovascular Island Pedicle Flap Obtained From Long Finger.

    Science.gov (United States)

    Liu, Hongjun; Regmi, Subhash; He, Yanyan; Hou, Ruixing

    2016-10-01

    Thumb tip reconstruction has been a very challenging issue for hand surgeons. Varieties of reconstructive options have been described or modified to obtain satisfactory sensory recovery. However, none has yielded entirely satisfactory results. This study reports a retrospective review of clinical data records of patients treated with a neurovascular island pedicle flap obtained from the medial aspect of the long finger. We enrolled 15 patients (9 men and 6 women), who received neurovascular island pedicle flaps for thumb tip amputations between December 2011 and December 2015. The average size of the flap was 2.8 × 2.2 cm(2) (range 2.5 × 1.8 cm(2) to 3.5 × 2.5 cm(2)). At the final follow-up visits, static two-point discrimination, visual analogue scale, Michigan hand outcome questionnaire and return-to-work time were used to evaluate surgical outcomes. All flaps survived well. The follow-up period was 18 months. The mean static 2PD values at the reconstructed thumb tip and donor finger pulp (medial side) were 5.3 mm (range 4-8 mm) and 3.2 mm (range 3-4 mm), respectively. The average VAS scores for the aesthetic appearance of the donor site and recipient site were 9.1 (range 8-10) and 9.0 (range 8-9.5), respectively. The average Michigan Hand Outcome Questionnaire (MHOQ) score for hand function (reconstructed hand) was 8.2 (range 6-16). The average RTW time was 8.4 weeks (range 7-12 weeks). Neurovascular island pedicle flap obtained from the medial aspect of long finger is a very reliable alternative technique for thumb tip defect reconstruction. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

  13. Biologically Inspired Modular Neural Networks

    OpenAIRE

    Azam, Farooq

    2000-01-01

    This dissertation explores the modular learning in artificial neural networks that mainly driven by the inspiration from the neurobiological basis of the human learning. The presented modularization approaches to the neural network design and learning are inspired by the engineering, complexity, psychological and neurobiological aspects. The main theme of this dissertation is to explore the organization and functioning of the brain to discover new structural and learning ...

  14. Musical experts recruit action-related neural structures in harmonic anomaly detection: evidence for embodied cognition in expertise.

    Science.gov (United States)

    Sherwin, Jason; Sajda, Paul

    2013-11-01

    Humans are extremely good at detecting anomalies in sensory input. For example, while listening to a piece of Western-style music, an anomalous key change or an out-of-key pitch is readily apparent, even to the non-musician. In this paper we investigate differences between musical experts and non-experts during musical anomaly detection. Specifically, we analyzed the electroencephalograms (EEG) of five expert cello players and five non-musicians while they listened to excerpts of J.S. Bach's Prelude from Cello Suite No. 1. All subjects were familiar with the piece, though experts also had extensive experience playing the piece. Subjects were told that anomalous musical events (AMEs) could occur at random within the excerpts of the piece and were told to report the number of AMEs after each excerpt. Furthermore, subjects were instructed to remain still while listening to the excerpts and their lack of movement was verified via visual and EEG monitoring. Experts had significantly better behavioral performance (i.e. correctly reporting AME counts) than non-experts, though both groups had mean accuracies greater than 80%. These group differences were also reflected in the EEG correlates of key-change detection post-stimulus, with experts showing more significant, greater magnitude, longer periods of, and earlier peaks in condition-discriminating EEG activity than novices. Using the timing of the maximum discriminating neural correlates, we performed source reconstruction and compared significant differences between cellists and non-musicians. We found significant differences that included a slightly right lateralized motor and frontal source distribution. The right lateralized motor activation is consistent with the cortical representation of the left hand - i.e. the hand a cellist would use, while playing, to generate the anomalous key-changes. In general, these results suggest that sensory anomalies detected by experts may in fact be partially a result of an embodied

  15. Developing a Graphical User Interface to Automate the Estimation and Prediction of Risk Values for Flood Protective Structures using Artificial Neural Network

    Science.gov (United States)

    Hasan, M.; Helal, A.; Gabr, M.

    2014-12-01

    In this project, we focus on providing a computer-automated platform for a better assessment of the potential failures and retrofit measures of flood-protecting earth structures, e.g., dams and levees. Such structures play an important role during extreme flooding events as well as during normal operating conditions. Furthermore, they are part of other civil infrastructures such as water storage and hydropower generation. Hence, there is a clear need for accurate evaluation of stability and functionality levels during their service lifetime so that the rehabilitation and maintenance costs are effectively guided. Among condition assessment approaches based on the factor of safety, the limit states (LS) approach utilizes numerical modeling to quantify the probability of potential failures. The parameters for LS numerical modeling include i) geometry and side slopes of the embankment, ii) loading conditions in terms of rate of rising and duration of high water levels in the reservoir, and iii) cycles of rising and falling water levels simulating the effect of consecutive storms throughout the service life of the structure. Sample data regarding the correlations of these parameters are available through previous research studies. We have unified these criteria and extended the risk assessment in term of loss of life through the implementation of a graphical user interface to automate input parameters that divides data into training and testing sets, and then feeds them into Artificial Neural Network (ANN) tool through MATLAB programming. The ANN modeling allows us to predict risk values of flood protective structures based on user feedback quickly and easily. In future, we expect to fine-tune the software by adding extensive data on variations of parameters.

  16. Artificial neural network modelling

    CERN Document Server

    Samarasinghe, Sandhya

    2016-01-01

    This book covers theoretical aspects as well as recent innovative applications of Artificial Neural networks (ANNs) in natural, environmental, biological, social, industrial and automated systems. It presents recent results of ANNs in modelling small, large and complex systems under three categories, namely, 1) Networks, Structure Optimisation, Robustness and Stochasticity 2) Advances in Modelling Biological and Environmental Systems and 3) Advances in Modelling Social and Economic Systems. The book aims at serving undergraduates, postgraduates and researchers in ANN computational modelling. .

  17. Modeling and possible implementation of self-learning equivalence-convolutional neural structures for auto-encoding-decoding and clusterization of images

    Science.gov (United States)

    Krasilenko, Vladimir G.; Lazarev, Alexander A.; Nikitovich, Diana V.

    2017-08-01

    Self-learning equivalent-convolutional neural structures (SLECNS) for auto-coding-decoding and image clustering are discussed. The SLECNS architectures and their spatially invariant equivalent models (SI EMs) using the corresponding matrix-matrix procedures with basic operations of continuous logic and non-linear processing are proposed. These SI EMs have several advantages, such as the ability to recognize image fragments with better efficiency and strong cross correlation. The proposed clustering method of fragments with regard to their structural features is suitable not only for binary, but also color images and combines self-learning and the formation of weight clustered matrix-patterns. Its model is constructed and designed on the basis of recursively processing algorithms and to k-average method. The experimental results confirmed that larger images and 2D binary fragments with a large numbers of elements may be clustered. For the first time the possibility of generalization of these models for space invariant case is shown. The experiment for an image with dimension of 256x256 (a reference array) and fragments with dimensions of 7x7 and 21x21 for clustering is carried out. The experiments, using the software environment Mathcad, showed that the proposed method is universal, has a significant convergence, the small number of iterations is easily, displayed on the matrix structure, and confirmed its prospects. Thus, to understand the mechanisms of self-learning equivalence-convolutional clustering, accompanying her to the competitive processes in neurons, and the neural auto-encoding-decoding and recognition principles with the use of self-learning cluster patterns is very important which used the algorithm and the principles of non-linear processing of two-dimensional spatial functions of images comparison. These SIEMs can simply describe the signals processing during the all training and recognition stages and they are suitable for unipolar

  18. Neural Networks

    Directory of Open Access Journals (Sweden)

    Schwindling Jerome

    2010-04-01

    Full Text Available This course presents an overview of the concepts of the neural networks and their aplication in the framework of High energy physics analyses. After a brief introduction on the concept of neural networks, the concept is explained in the frame of neuro-biology, introducing the concept of multi-layer perceptron, learning and their use as data classifer. The concept is then presented in a second part using in more details the mathematical approach focussing on typical use cases faced in particle physics. Finally, the last part presents the best way to use such statistical tools in view of event classifers, putting the emphasis on the setup of the multi-layer perceptron. The full article (15 p. corresponding to this lecture is written in french and is provided in the proceedings of the book SOS 2008.

  19. Mandible vertical height correction using lingual bone-split pedicle onlay graft technique

    Directory of Open Access Journals (Sweden)

    Coen Pramono D

    2006-09-01

    Full Text Available As edentulous mandible become atrophic, a denture bearing area will also be reduced. Difficulty in the removable prosthesis rehabilitation will be present as well. The purpose of this paper reports an innovative surgical technique to cope a problem of unstable complete lower denture due to bone atrophy and resulted of vertical height reduction of the anterior region of the mandible necessary for denture retention. Vertical advancement of the lower jaw using lingual bone split pedicle onlay graft technique in the anterior region of the mandible and followed by secondary epithelization vestibuloplasty in achieving the vertical height dimension. The surgery was achieved satisfactorily as the vertical dimension of the mandible anterior region had increased and the denture seated more stable comparing with the previous denture worn by the patient. It concluded that the surgery was achieved with a great result as the vertical height of the anterior region of the mandible had increased positively therefore lead the denture seated more stable.

  20. Traumatic dislocation of the S1 polyaxial pedicle screw head: a case report.

    Science.gov (United States)

    Du Plessis, Pieter N B; Lau, Bernard P H; Hey, Hwee Weng Dennis

    2017-03-01

    Polyaxial screw head dislocation in the absence of a manufacture defect is extremely rare and represents a biomechanical overload of the screw, leading to early failure. A 58-year-old gentleman underwent instrumented fusion using polyaxial pedicle screws-titanium rod construct with interbody cage for spondylolytic spondylolisthesis at the L5/S1 level. He attempted to bend forward ten days after the surgery which resulted in a dislocation of the right S1 polyaxial screw head from the screw shank with recurrence of symptoms. He underwent revision surgery uneventfully. This case highlights the need to pay particular attention to the strength of fixation and the amount of release to avoid such a complication.

  1. Posterior keyhole corpectomy with percutaneous pedicle screw stabilization in the surgical management of lumbar burst fractures.

    Science.gov (United States)

    Maciejczak, Andrzej; Barnas, Piotr; Dudziak, Piotr; Jagiełło-Bajer, Barbara; Litwora, Bogdan; Sumara, Mateusz

    2007-04-01

    The authors present a new method of minimally invasive surgical management of lumbar burst fractures through the posterior approach. The method includes minimally invasive corpectomy and interbody fusion, both of which are performed through a keyhole approach, and percutaneous pedicle screw fixation of the fracture. The technique of the posterior keyhole corpectomy presented in this report is a novel and original concept of the first author (AM). The percutaneous pedicle screw stabilization is performed with the use of a percutaneous instrumentation system (Sextant; Medtronic, Inc., Minneapolis, MN). The Sextant system has been dedicated and used in nontrauma degenerative cases; the novel aspect of this system is its application in spine fractures. Indications for the method include Denis classification subtype B or Magerl subtype A.3.1 burst fractures. Both subtypes represent fractures with failure and retropulsion of the upper part of the vertebral body. The clinical experience of this study includes four cases of burst fractures with significant retropulsion and occlusion of the spinal canal. Long-term results were assessed at a minimum follow-up period of 1 year (maximum, 3.5 yr). The follow-up assessments included: 1) the quality of decompression and reconstruction of the spinal canal (computed tomographic and magnetic resonance imaging scanning); 2) the stability of the operated segment (dynamic x-rays); 3) the quality of interbody fusion (computed tomographic scanning and dynamic x-rays); and 4) correction of the fracture kyphosis and its postoperative loss (measurements of Cobb angles for the assessment of sagittal plane deformity). The minimum armamentarium requirements for this method include a typical micro lumbar discectomy retractor set; a surgical microscope; two-plane intraoperative fluoroscopy; and a system for percutaneous pedicle screw stabilization (Sextant). "Posterior keyhole corpectomy" indicates corpectomy of the posterior upper half of the

  2. Free tissue transfer versus pedicled flap reconstruction of head and neck malignancy defects.

    LENUS (Irish Health Repository)

    O'Neill, J P

    2012-02-01

    BACKGROUND: With the advent of microsurgery the pedicled flap is considered by many to be an outdated surgical option. AIMS: To explore the relationship between flap survival and pre-morbid risk factors, conduct a comparative analysis of flap and systemic morbidities and complete a cosmesis and functionality assessment for oral and oropharyngeal reconstruction patients. METHODS: 114 patients, over a 13-year period, who had a one-stage reconstructive procedure employing the pectoralis major myocutaneous flap (PMMF) or radial forearm-free flap (RFFF). RESULTS: Variables, including age, smoking and radiation exposure were not statistically significant predictors of flap survival probability. Atelectasis was a significant post-op finding of RFFF patients. Flap dehiscence of >50% was a significant morbidity of PMMF. No statistical difference in cosmetic deformity, diet and socialisation was noted. CONCLUSIONS: Pectoralis major myocutaneous flap remains an enduring and safe flap; however, the RFFF has markedly improved speech performance over the PMMF.

  3. Percutaneous pedicle screw for unstable spine fractures in polytraumatized patients: A report of two cases

    Directory of Open Access Journals (Sweden)

    Boon Beng Tan

    2012-01-01

    Full Text Available Unstable spine fractures commonly occur in the setting of a polytraumatized patient. The aim of management is to balance the need for early operative stabilization and prevent additional trauma due to the surgery. Recent published literature has demonstrated the benefits of early stabilization of an unstable spine fracture particularly in patients with higher injury severity score (ISS. We report two cases of polytrauma with unstable spine fractures stabilized with a minimally invasive percutaneous pedicle screw instrumentation system as a form of damage control surgery. The patients had good recovery from the polytrauma injuries. These two cases illustrate the role of minimally invasive stabilization, its limitations and technical pitfalls in the management of unstable spine fractures in the polytrauma setting as a form of damage control surgery.

  4. Pedicled Instep Flap and Tibial Nerve Reconstruction in a Cynomolgus Monkey [Macaca fascicularis

    Directory of Open Access Journals (Sweden)

    Ruth Weiss

    2016-01-01

    Full Text Available A male cynomolgus monkey experienced extensive soft tissue trauma to the right caudal calf area. Some weeks after complete healing of the original wounds, the monkey developed a chronic pressure sore on plantar surface of the heel of its right foot. A loss of sensitivity in the sole of the foot was hypothesized. The skin defect was closed by a medial sensate pedicled instep flap followed by counter transplantation of a full thickness graft from the interdigital webspace. The integrity of the tibial nerve was revised and reconstructed by means of the turnover flap technique. Both procedures were successful. This is an uncommon case in an exotic veterinary patient as it demonstrates a reconstructive skin flap procedure for the treatment of a chronic, denervated wound in combination with the successful reconstruction of 2.5 cm gap in the tibial nerve.

  5. Cicatricial ectropion due to essential skin shrinkage: treatment with rotational upper-lid pedicle flaps.

    Science.gov (United States)

    Hurwitz, J J; Lichter, M; Rodgers, J

    1983-10-01

    Ectropion is sometimes due to a shortage of skin of the lower lid (cicatricial) and may result from previous surgery, trauma, burns, skin diseases etc. Excessive exposure to the sun has also been incriminated. Vertical traction lines in the skin of the lower lid, accentuated by gazing up or by opening the mouth, suggest this condition. This paper describes the use of pedicle skin flaps rotated from the upper lid to treat cicatricial ectropion occurring in the absence of any predisposing factor and not responding to conservative treatment--that is, due to essential skin shrinkage. All 10 patients had an improved appearance, and epiphora persisted in only 1 patient, who subsequently underwent a punctum-enlarging procedure. In an 11th patient there was insufficient redundant upper-lid skin, so a free skin graft was used instead.

  6. Successful pregnancy "during" pedicled transverse rectus abdominis musculocutaneous flap for breast reconstruction with normal vaginal delivery

    Directory of Open Access Journals (Sweden)

    Siew Cheng Chai

    2015-01-01

    Full Text Available A transverse rectus abdominis myocutaneous (TRAM flap is a popular choice for breast reconstruction. Pregnancies in women following a TRAM flap present concerns regarding both safety and the integrity of the abdominal wall. We report a case of a patient who was pregnant during immediate breast reconstruction with pedicled TRAM flap and had a successful spontaneous vaginal delivery. We also conducted a literature review using PubMed on pregnancy post TRAM flap, type of reconstruction, timing of pregnancy after TRAM flap, complication, and mode of delivery, which are summarised in this report. We concluded that patients may have safe pregnancies and normal deliveries following TRAM flap breast reconstruction regardless of the time frame of pregnancy after the procedure. Therefore, TRAM flaps can continue to be a reconstruction option, even in women of childbearing age.

  7. One stage reconstruction of the floor of the mouth with a subcutaneous pedicled nasolabial flap.

    Science.gov (United States)

    El-Marakby, Hamdy H; Fouad, Fouad A; Ali, Ahmed H

    2012-06-01

    Nasolabial flaps have been recognised as versatile flaps for a variety of defects in the face, nose, lip and the oral cavity. Random pattern inferiorly based nasolabial flaps (NLF) have been utilised for covering small defects on the anterior floor of the mouth, but usually require a second stage procedure to divide the flap base. A subcutaneous pedicled inferiorly based nasolabial flap can provide a one stage repair of moderate sized defects of the floor of the mouth after de epithelialisation of the base of the flap. To evaluate the feasibility of a single stage reconstruction of intermediate sized defects in the oral cavity with an inferiorly based pedicled NLF. The study includes the indications of use of the flap, flap design, technique, and the complications rate. The incidence of secondary procedures and the final functional and the aesthetic results will also be evaluated. A group of 20 patients presented with (T1-2) squamous cell carcinoma of the oral cavity have been treated at the Department of Surgery, National Cancer Institute, Cairo; in the period between January 2008 and September 2010. The pathology was confirmed with an incision biopsy and all metastatic work were carried out confirming that all patients were free from distant metastasis at presentation. Preoperative assessment also included assessment of the stage of the disease, the flap design and patient fitness for general anaesthesia. All patients underwent surgical excision combined with reconstruction of the defect with a subcutaneous inferiorly based pedicled NLF. The proximal part of the flap was routinely de epithelialised before it has been tunnelled through the cheek so a one stage procedure could only be required. The mean age of the patients was 62.3±6years, range (52-69years). All patients were diagnosed with squamous cell carcinoma. The anterior floor of the mouth constituted 40% of the defects, the lateral floor of the mouth 20% and the inner surface of the cheek 40%. There was

  8. Principal Component Analysis Coupled with Artificial Neural Networks—A Combined Technique Classifying Small Molecular Structures Using a Concatenated Spectral Database

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    Mihail Lucian Birsa

    2011-10-01

    Full Text Available In this paper we present several expert systems that predict the class identity of the modeled compounds, based on a preprocessed spectral database. The expert systems were built using Artificial Neural Networks (ANN and are designed to predict if an unknown compound has the toxicological activity of amphetamines (stimulant and hallucinogen, or whether it is a nonamphetamine. In attempts to circumvent the laws controlling drugs of abuse, new chemical structures are very frequently introduced on the black market. They are obtained by slightly modifying the controlled molecular structures by adding or changing substituents at various positions on the banned molecules. As a result, no substance similar to those forming a prohibited class may be used nowadays, even if it has not been specifically listed. Therefore, reliable, fast and accessible systems capable of modeling and then identifying similarities at molecular level, are highly needed for epidemiological, clinical, and forensic purposes. In order to obtain the expert systems, we have preprocessed a concatenated spectral database, representing the GC-FTIR (gas chromatography-Fourier transform infrared spectrometry and GC-MS (gas chromatography-mass spectrometry spectra of 103 forensic compounds. The database was used as input for a Principal Component Analysis (PCA. The scores of the forensic compounds on the main principal components (PCs were then used as inputs for the ANN systems. We have built eight PC-ANN systems (principal component analysis coupled with artificial neural network with a different number of input variables: 15 PCs, 16 PCs, 17 PCs, 18 PCs, 19 PCs, 20 PCs, 21 PCs and 22 PCs. The best expert system was found to be the ANN network built with 18 PCs, which accounts for an explained variance of 77%. This expert system has the best sensitivity (a rate of classification C = 100% and a rate of true positives TP = 100%, as well as a good selectivity (a rate of true negatives TN

  9. The neural cell adhesion molecule

    DEFF Research Database (Denmark)

    Berezin, V; Bock, E; Poulsen, F M

    2000-01-01

    During the past year, the understanding of the structure and function of neural cell adhesion has advanced considerably. The three-dimensional structures of several of the individual modules of the neural cell adhesion molecule (NCAM) have been determined, as well as the structure of the complex...... between two identical fragments of the NCAM. Also during the past year, a link between homophilic cell adhesion and several signal transduction pathways has been proposed, connecting the event of cell surface adhesion to cellular responses such as neurite outgrowth. Finally, the stimulation of neurite...

  10. Radiological analysis of ankylosing spondylitis patients with severe kyphosis before and after pedicle subtraction osteotomy.

    Science.gov (United States)

    Debarge, Romain; Demey, Guillaume; Roussouly, Pierre

    2010-01-01

    This is a radiographic study of ankylosing spondylitis patients with severe fixed kyphotic deformity who underwent pedicle subtraction osteotomy. Our goal was to measure and validate new angle to assess global kyphosis and to evaluate the radiological outcomes after surgery. This is the first report which describes new angle to assess global kyphosis (T1-S1). Pre and postoperative controls were compared according to the Pelvic Incidence. The sagittal parameters ankylosing spondylitis patients were compared with 154 asymptomatic patients. In addition to the pelvic parameters and the C7 tilt, we used the spino-sacral angle. Pelvic incidence in ankylosing spondylitis patients was higher than asymptomatic population (61 vs. 51 degrees). For a same tilt of C7 for both groups, the low pelvic incidence group had a lower sacral slope and pelvic tilt and a higher global kyphosis (spino-sacral angle = 90 degrees) than the high pelvic incidence group (spino-sacral angle = 98 degrees ). In the adult volunteers, the C7 tilt and spino-sacral angle measured, respectively, 95 and 135 degrees. The preoperative C7 tilt measured 73 degrees and increased to 83 degrees (p = 0.0025). The preoperative spino-sacral angle measured 96 degrees and increased to 113.3 degrees (p = 0.003). A low pelvic incidence pelvis has a lower sacral slope than in high pelvic incidence and can support a bigger kyphosis. All the parameters were improved by the pedicle subtraction osteotomy, but the average spino-sacral angle remained lower than the control group. When C7 tilt was useful to assess the improvement of the balance, SSA allowed a better evaluation of the correction of kyphosis itself.

  11. Comparison between two pedicle screw augmentation instrumentations in adult degenerative scoliosis with osteoporosis

    Science.gov (United States)

    2011-01-01

    Background The operative treatment of adult degenerative scoliosis combined with osteoporosis increase following the epidemiological development. Studies have confirmed that screws in osteoporotic spines have significant lower-screw strength with more frequent screw movements within the vertebra than normal spines. Screws augmented with Polymethylmethacrylate (PMMA) or with autogenous bone can offer more powerful corrective force and significant advantages. Methods A retrospective analysis was conducted on 31 consecutive patients with degenerative lumbar scoliosis combined with osteoporosis who had surgery from December 2000. All had a minimum of 2-year follow-up. All patients had posterior approach surgery. 14 of them were fixed with pedicle screw by augmentation with Polymethylmethacrylate (PMMA) and the other 17 patients with autogenous bone. Age, sex and whether smoking were similar between the two groups. Surgical time, blood loss, blood transfusion, medical cost, post surgery ICU time, hospital day, length of oral pain medicines taken, Pre-and postoperative Oswestry disability index questionnaire and surgical revision were documented and compared. Preoperative, postoperative and final follow up Cobb angle, sagittal lumbar curve, correction rate, and Follow up Cobb loss were also compared. Results No significant differences were found between the autogenous bone group and Polymethylmethacrylate group with regards to all the targets above except for length of oral pain medicines taken and surgery cost. 2 patients were seen leakage during operation, but there is neither damage of nerve nor symptom after operation. No revision was needed. Conclusion Both augmentation pedicle screw with Polymethylmethacrylate (PMMA) and autogenous bone treating degenerative lumbar scoliosis combined with osteoporosis can achieve a good surgical result. Less oral pain medicines taken are the potential benefits of Polymethylmethacrylate augmentation, but that is at the cost of more

  12. Patterns of flap loss related to arterial and venous insufficiency in the rat pedicled TRAM flap.

    Science.gov (United States)

    Qiao, Q; Moon, W; Zhang, F; Chen, S G; Kunda, L; Lineaweaver, W C; Buncke, H J

    1999-08-01

    Vascular supply to the contralateral portion of the conventional transverse rectus abdominis musculocutaneous (TRAM) flap (zone IV) may become compromised, resulting in partial flap loss and requiring segmental excision. The etiology of this necrosis is not clear. This study determines skin necrosis patterns on a superiorly pedicled caudal TRAM flap during conditions of venous and arterial insufficiency, and determines whether cutaneous venous outflow can sustain a flap with venous insufficiency. Twenty-eight adult male Sprague-Dawley rats underwent superior pedicled TRAM flap elevation, and the zones were marked on the skin paddle. The animals were divided into four groups: control (group A, N = 6), arterial ligation (group B, N = 6), venous ligation (group C, N = 8), and venous ligation with cutaneous venous outflow (group D, N = 8). After 10 days, the skin paddle was photographed and the areas of necrotic skin were measured. Results showed that group B (selective arterial ligation) had 51.7 +/- 2.8% and 40.0 +/- 2.0% skin necrosis in zones I and II respectively. Zone I necrosis was significantly greater in group B compared with the control (p < 0.05). Group C (selective venous ligation) resulted in 73.8 +/- 16.4% and 93.8 +/- 33.4% skin necrosis in zones III and IV respectively. This necrosis was significantly greater compared with the control (p < 0.001). Group D rats' lateral skin necrosis compared significantly less with group C (p < 0.001). These results demonstrate that the patterns of flap necrosis in rat TRAM flaps with poor arterial inflow differ from those with venous stasis. Necrosis of the contralateral portion (zone IV) of human TRAM flaps may be related to problems with venous stasis; thus, a cutaneous venous outflow may prevent this problem.

  13. Osteocutaneous pedicle flap transfer for salvage of transtibial amputation after severe lower-extremity injury.

    Science.gov (United States)

    Vallier, Heather A; Fitzgerald, Steven J; Beddow, Meghan E; Sontich, John K; Patterson, Brendan M

    2012-03-07

    A conventional transtibial amputation may not be possible when the zone of injury involves the proximal part of the tibia, or in cases of massive tibial bone and/or soft-tissue loss. The purpose of this study was to examine the outcomes of salvage of a transtibial amputation level with a rotational osteocutaneous pedicle flap from the ipsilateral hindfoot. Fourteen patients who had an osteocutaneous pedicle flap from the ipsilateral foot were included in the study. Twelve patients were followed for more than twenty-four months (mean, 60.2 months) and were evaluated with use of the Sickness Impact Profile (SIP), Musculoskeletal Function Assessment (MFA), and a 100-ft (30.48-m) timed walking test. There were ten men and four women with mean age of 43.2 years. Thirteen patients had a type-IIIB open tibial fracture, and one had extensive soft-tissue loss secondary to a burn. Four patients were treated for infection after the index procedure. There were no nonunions of the tibia to the calcaneus. Three patients underwent late reconstructive procedures to improve prosthetic fit. No patient required subsequent revision to a more proximal amputation level. Mean knee flexion was 139°. A novel technique has been developed to salvage a transtibial amputation level with use of a rotational osteocutaneous flap from the hindfoot. In the absence of adequate tibial length and/or soft-tissue coverage to salvage the entire limb or to perform a conventional-length transtibial amputation, this technique is a highly functional alternative that does not require microvascular free tissue transfer.

  14. Management of major vascular injury during pedicle screw instrumentation of thoracolumbar spine.

    Science.gov (United States)

    Mirza, Aleem K; Alvi, Mohammed Ali; Naylor, Ryan M; Kerezoudis, Panagiotis; Krauss, William E; Clarke, Michelle J; Shepherd, Daniel L; Nassr, Ahmad; DeMartino, Randall R; Bydon, Mohamad

    2017-12-01

    Vascular injury is a rare complication of spinal instrumentation. Presentation can vary from immediate hemorrhage to pseudoaneurysm formation. In the literature, surgical approach to repair has varied based on anatomy, acuity of diagnosis, infection, and available technology. In this manuscript, we aim to describe our institutional experience with vascular injuries in thoraco-lumbar spine surgery. We report our institutional experience of three cases of vascular injury secondary to pedicle screw misplacement and their management, as well as a review of the literature. The first case had a history of previous instrumentation and presented with back pain and fever. The patient was taken for instrumentation exploration via a posterior approach. Aortic violation was discovered at T6 intraoperatively during instrumentation removal and the patient underwent emergent endovascular repair. The second case presented with chronic back pain after multiple prior posterior fusions and CT angiogram showing screw perforation on the aorta at T10. The patient underwent elective endovascular repair with synchronous removal of the instrumentation. The third case presented with radicular leg pain 6 months after L4-S1 posterior lumbar interbody fusion, with CT scan demonstrating the left S1 screw abutting the L5 nerve root and common iliac vein. The patient underwent elective instrumentation revision with intraoperative venography. Major vascular injury is a known complication of spinal surgery, especially if it involves instrumentation with pedicle screws. Treatment approach has evolved with the advancement of endovascular technology; however, open surgery remains an option when anatomy or infection is prohibitive. In the elective setting, preoperative planning with attention to surgical approach, positioning, and contingencies, should occur in a multidisciplinary fashion. Repair with an aortic stent-graft cuff may minimize unnecessary coverage of the descending thoracic aorta and

  15. Spontaneus bilateral pedicle fracture 30 years after Harrington Instrumentation for idiopathic scoliosis: a case report

    Directory of Open Access Journals (Sweden)

    Obid Peter

    2012-01-01

    Full Text Available Abstract Introduction Spontaneous fractures of the spine are a common entity. They usually occur in older people with osteoporosis. This case is presented on account of its rarity. To the best of the authors' knowledge only one case of an osteoporotic pedicle fracture after Harrington Instrumentation has been described before. Case presentation We report the case of a 46-year-old Caucasian woman who underwent surgery due to idiopathic scoliosis with a Harrington Instrumentation (T4 to L3 30 years ago. During the operation she was infected with hepatitis C while receiving erythrocyte concentrates and has suffered from liver cirrhosis since then. She presented with a sudden pain in her lower back and paraesthesia in both her legs but no other neurological symptoms. A computed tomography scan showed a bilateral pedicle fracture of L3 and an additional compression fracture of L4. In the first session we performed a dorsal stabilization with massive intraoperative bleeding and a postoperative failure of liver synthesis. In a second session an additional ventral augmentation was done. After the second operation she developed a hepatorenal syndrome. Both operations left the patient in a very critical state which led to a prolonged stay in the intensive care and rehabilitation unit. At her 12-month follow-up visit, she was free of complaints. Conclusion The un-physiological load of the spine after Harrington Instrumentation can lead to osteoporosis due to inactivity even in younger patients. Although these implants are not used anymore one should keep this possibility in mind when dealing with patients who have received Harrington rods in surgical procedures.

  16. Thoracic pedicle subtraction osteotomy in a pediatric patient: a case report

    Science.gov (United States)

    Silverstein, Michael P.; St Clair, Selvon F.; Lieberman, Isador H.

    2012-01-01

    Study design: Case report. Objective: To describe a case of thoracic pedicle subtraction osteotomy (PSO) for congenital kyphosis in a child. Background information: Although congenital kyphosis is rare, it is a challenging cause of pediatric myelopathy and frank paralysis. Even less common is the use of PSO for the surgical management of focal congenital kyphosis. We present the case of a child with congenital kyphosis that was managed with a pedicle subtraction osteotomy. Methods: A detailed history and physical examination were performed with careful review of the patient’s medical records and x-ray studies. A PSO at T11 was performed along with T9 through L1 instrumented posterolateral fusion. Case description: A 10-year-old girl was evaluated for walking difficulty and a lump on her back. Physical examination revealed a sharp gibbus kyphosis in the lower thoracic spine with tenderness and bilateral back muscle spasms. The patient displayed difficulty with balance lacking a smooth, regular gait rhythm. Clonus and radiculopathy were not present. Plain x-ray of the thoracolumbar spine revealed hyperkyphosis and failure of anterior wall segmentation between T10 and T11 vertebral bodies. Cobb’s angle measured 65 degrees. Due to her symptoms and degree of correction required, we elected to perform a PSO at T11 along with T9 to L1 posterolateral instrumentation fusion. No intraoperative complications occurred. There was a significant improvement in her posture and gait. Discussion: A thoracic PSO for congenital kyphosis was safely performed with an excellent outcome. To our knowledge, this is the first PSO procedure performed in Uganda. PMID:23230419

  17. Novel free-hand T1 pedicle screw method: Review of 44 consecutive cases

    Directory of Open Access Journals (Sweden)

    Mark A Rivkin

    2014-01-01

    Full Text Available Summary of Background Data: Multilevel posterior cervical instrumented fusions are becoming more prevalent in current practice. Biomechanical characteristics of the cervicothoracic junction may necessitate extending the construct to upper thoracic segments. However, fixation in upper thoracic spine can be technically demanding owing to transitional anatomy while suboptimal placement facilitates vascular and neurologic complications. Thoracic instrumentation methods include free-hand, fluoroscopic guidance, and CT-based image guidance. However, fluoroscopy of upper thoracic spine is challenging secondary to vertebral geometry and patient positioning, while image-guided systems present substantial financial commitment and are not readily available at most centers. Additionally, imaging modalities increase radiation exposure to the patient and surgeon while potentially lengthening surgical time. Materials and Methods: Retrospective review of 44 consecutive patients undergoing a cervicothoracic fusion by a single surgeon using the novel free-hand T1 pedicle screw technique between June 2009 and November 2012. A starting point medial and cephalad to classic entry as well as new trajectory were utilized. No imaging modalities were employed during screw insertion. Postoperative CT scans were obtained on day 1. Screw accuracy was independently evaluated according to the Heary classification. Results: In total, 87 pedicle screws placed were at T1. Grade 1 placement occurred in 72 (82.8% screws, Grade 2 in 4 (4.6% screws and Grade 3 in 9 (10.3% screws. All Grade 2 and 3 breaches were <2 mm except one Grade 3 screw breaching 2-4 mm laterally. Only two screws (2.3% were noted to be Grade 4, both breaching medially by less than 2 mm. No new neurological deficits or returns to operating room took place postoperatively. Conclusions: This modification of the traditional starting point and trajectory at T1 is safe and effective. It attenuates additional bone

  18. Therapeutic reduction mammoplasty in large-breasted women with cancer using superior and superomedial pedicles

    Directory of Open Access Journals (Sweden)

    Denewer A

    2012-10-01

    Full Text Available Adel Denewer,1 Fayez Shahatto,1 Waleed Elnahas,1 Omar Farouk,1 Sameh Roshdy,1 Ashraf Khater,1 Osama Hussein,1