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Sample records for analysis surrounding implant-supported

  1. Effect of type of luting agents on stress distribution in the bone surrounding implants supporting a three-unit fixed dental prosthesis: 3D finite element analysis

    PubMed Central

    Ghasemi, Ehsan; Abedian, Alireza; Iranmanesh, Pedram; Khazaei, Saber

    2015-01-01

    Background: Osseointegration of dental implants is influenced by many biomechanical factors that may be related to stress distribution. The aim of this study was to evaluate the effect of type of luting agent on stress distribution in the bone surrounding implants, which support a three-unit fixed dental prosthesis (FDP) using finite element (FE) analysis. Materials and Methods: A 3D FE model of a three-unit FDP was designed replacing the maxillary first molar with maxillary second premolar and second molar as the abutments using CATIA V5R18 software and analyzed with ABAQUS/CAE 6.6 version. The model was consisted of 465108 nodes and 86296 elements and the luting agent thickness was considered 25 μm. Three load conditions were applied on eight points in each functional cusp in horizontal (57.0 N), vertical (200.0 N) and oblique (400.0 N, θ = 120°) directions. Five different luting agents were evaluated. All materials were assumed to be linear elastic, homogeneous, time independent and isotropic. Results: For all luting agent types, the stress distribution pattern in the cortical bone, connectors, implant and abutment regions was almost uniform among the three loads. Furthermore, the maximum von Mises stress of the cortical bone was at the palatal side of second premolar. Likewise, the maximum von Mises stress in the connector region was in the top and bottom of this part. Conclusion: Luting agents transfer the load to cortical bone and different types of luting agents do not affect the pattern of load transfer. PMID:25709676

  2. Fracture analysis of randomized implant-supported fixed dental prostheses

    PubMed Central

    Esquivel-Upshaw, Josephine F.; Mehler, Alex; Clark, Arthur E.; Neal, Dan; Anusavice, Kenneth J.

    2014-01-01

    Objective Fractures of posterior fixed dental all-ceramic prostheses can be caused by one or more factors including prosthesis design, flaw distribution, direction and magnitude of occlusal loading, and nature of supporting infrastructure (tooth root/implant), and presence of adjacent teeth. This clinical study of implant-supported, all-ceramic fixed dental prostheses, determined the effects of (1) presence of a tooth distal to the most distal retainer; (2) prosthesis loading either along the non-load bearing or load bearing areas; (3) presence of excursive contacts or maximum intercuspation contacts in the prosthesis; and (4) magnitude of bite force on the occurrence of veneer ceramic fracture. Methods 89 implant-supported FDPs were randomized as either a three-unit posterior metal-ceramic (Au-Pd-Ag alloy and InLine POM, Ivoclar, Vivadent) FDP or a ceramic-ceramic (ZirCAD and ZirPress, Ivoclar, Vivadent) FDP. Two implants (Osseospeed, Dentsply) and custom abutments (Atlantis, Dentsply) supported these FDPs, which were cemented with resin cement (RelyX Universal Cement). Baseline photographs were made with markings of teeth from maximum intercuspation (MI) and excursive function. Patients were recalled at 6 months and 1 to 3 years. Fractures were observed, their locations recorded, and images compared with baseline photographs of occlusal contacts. Conclusion No significant relationship exists between the occurrence of fracture and: (1) the magnitude of bite force; (2) a tooth distal to the most distal retainer; and (3) contacts in load-bearing or non-load-bearing areas. However, there was a significantly higher likelihood of fracture in areas with MI contacts only. Clinical Significance This clinical study demonstrates that there is a need to evaluate occlusion differently with implant-supported prostheses than with natural tooth supported prostheses because of the absence of a periodontal ligament. Implant supported prostheses should have minimal occlusion and

  3. Photoelastic stress analysis of splinted and unitary implant-supported prostheses

    NASA Astrophysics Data System (ADS)

    Pellizzer, Eduardo Piza; Santiago Junior, Joel Ferreira; Villa, Luiz Marcelo Ribeiro; de Souza Batista, Victor Eduardo; de Mello, Caroline Cantieri; de Faria Almeida, Daniel Augusto; Honório, Heitor Marques

    2014-10-01

    The aim of this study was to evaluate the effects that splinting and different lengths of implants have on the stress distribution in implant-supported prostheses by photoelastic analysis. A total of five photoelastic resin models were made with different proposed situations, and 400 load applications were performed for the analysis. Compared with the unitary prosthesis, the splinted implant-supported prosthesis acted favorably in the distribution of stresses and strains to the implant ( p < 0.001). The increase in length was a significant factor in the stress distribution ( p < 0.05) and, ultimately, the overall reduction in stress. It was concluded that the splinted implant-supported prosthesis behaved better biomechanically compared with the unitary prosthesis.

  4. Photoelastic stress analysis in screwed and cemented implant-supported dentures with external hexagon implants.

    PubMed

    Pellizzer, Eduardo Piza; Tonella, Bianca Piccolotto; Ferraço, Renato; Falcón-Antenucci, Rosse Mary; de Carvalho, Paulo Sérgio Perri; Alves-Rezende, Maria Cristina Rosifini

    2010-07-01

    The aim of this study was to assess the stress distribution of the retention systems (screwed and cemented) for implant-supported fixed partial dentures by means of photoelastic method. Two models were made of photoelastic resin PL-2 with 2 implants (phi = 4.00 x 10 mm) located in the second premolar and molar region in each photoelastic model, varying the retention system (screwed and cemented). The implant-supported fixed partial dentures were standardized and made of Ni-Cr alloy. Axial and oblique (45 degrees) forces of 100 N were applied on the occlusal surface by means of a Universal Testing Machine (EMIC-DL 3000; São José dos Pinhais, Paraná, Brazil). The results were observed and photographed in the field of a circular polariscope and qualitatively analyzed with the aid of computer software (Adobe Photoshop, San Jose, CA). The screw retention system presented the highest number of fringes when the loads were applied on the premolar, pontic, and molar and showed this behavior in all load applications, under axial and oblique loads. It was concluded that there was a better stress distribution and lower magnitude of stress on the cemented implant-supported dentures, under axial and oblique loads. Oblique load caused an increase in stress concentrations in all the models. PMID:20613577

  5. BIOMECHANICAL ANALYSIS OF THE STRESSES GENERATED BY DIFFERENT DISOCCLUSION PATTERNS IN AN IMPLANT-SUPPORTED MANDIBULAR COMPLETE DENTURE

    PubMed Central

    Greco, Gustavo Diniz; Jansen, Wellington Corrêa; Landre, Janis; Seraidarian, Paulo Isaías

    2009-01-01

    Objectives: This study evaluated by three-dimensional finite element analysis the tensions generated by different disocclusion patterns (canine guide and bilateral balanced occlusion) in an implant-supported mandibular complete denture. Material and Methods: A three-dimensional model of implant-supported mandibular complete denture was fabricated according to the Brånemark protocol. A 5-element 3.75 x 13-mm screw-shape dental implant system was modeled for this study. The implants were located in the intermental foramen region with 3-mm-high prosthetic components joined by a nickel-chromium framework with 12-mm bilateral cantilever covered by acrylic resin and 12 acrylic denture teeth. SolidWorks® software was used before and after processing the simulations. The mechanical properties of the components were inserted in the model and a 15 N load was established in fixed points, in each one of the simulations. Data were collected in the entire nickel-chromium framework. The results were displayed three-dimensionally as color graphic scales. Results: The canine guide generated greater tensions in the region of the first implant, while the bilateral balanced occlusion generated great tensions in the entire metallic framework. The maximum tension found in the simulation of the bilateral balanced occlusion was 3.22 fold higher than the one found in the simulation of the disocclusion in canine guide. Conclusion: The pattern of disocclusion in canine guide is the ideal for implant-supported mandibular complete denture. PMID:19936535

  6. An analysis of the implant-supported overdenture in the edentulous mandible.

    PubMed

    Chen, K-W; Lin, T-M; Liu, P-R; Ramp, L C; Lin, H-J; Wu, C-T; Pan, Y-H

    2013-01-01

    This investigation examined the cumulative survival rate of the implant-supported overdenture using two types of attachments in patients treated at Show Chwan Memorial Hospital Implant Center from 1992 to 2006. Fifty-one patients (30 men and 21 women) were treated with mandibular implant-supported overdentures. Attachment systems used were the Hader bar with bilateral, cast ERA attachments (Group A, 31 patients with 15 men and 16 women, 134 implants) and the Hader bar with bilateral, distal extension cantilevers (Group B, 20 patients with 15 men and 5 women, 85 implants). Two hundred and four implants remained at the end of the follow-up period. Among failed implants, 10 implants were in Group A (failure rate: 10/134 = 7·5%), whereas five implants were in Group B (failure rate: 5/85 = 5·9%). Sixty-six point seven per cent (10/15) of failed implants were placed in the distal anterior mandible, and 33·3% (5/15) were placed in the middle anterior mandible. Survival was also examined with respect to condition of the opposing arch. Patients wearing a maxillary removable partial denture had the highest implant failure rate (5/51 = 9·8%), whereas the failure rate of the maxillary complete denture group was only 5·7%. The most frequent need for maintenance was wear over patrix component of ERA or Hader clip (n = 56). Eight patients experienced connector fracture between ERA and Hader bar, and one experienced distal extension cantilever fracture. The implant-supported overdenture can be an effective and reliable alternative to the conventional complete mandibular denture. Fewer prosthetic complications were seen in overdentures retained with distal extension cantilever attachments. PMID:23121231

  7. Finite element analysis of provisional structures of implant-supported complete prostheses.

    PubMed

    Carneiro, Bruno Albuquerque; de Brito, Rui Barbosa; França, Fabiana Mantovani Gomes

    2014-04-01

    The use of provisional resin implant-supported complete dentures is a fast and safe procedure to restore mastication and esthetics of patients soon after surgery and during the adaptation phase to the new denture. This study assessed stress distribution of provisional implant-supported fixed dentures and the all-on-4 concept using self-curing acrylic resin (Tempron) and bis-acrylic resin (Luxatemp) to simulate functional loads through the three-dimensional finite element method. Solidworks software was used to build three-dimensional models using acrylic resin (Tempron, model A) and bis-acrylic resin (Luxatemp, model B) for denture captions. Two loading patterns were applied on each model: (1) right unilateral axial loading of 150 N on the occlusal surfaces of posterior teeth and (2) oblique loading vector of 150 N at 45°. The results showed that higher stress was found on the bone crest below oblique load application with a maximum value of 187.57 MPa on model A and 167.45 MPa on model B. It was concluded that model B improved stress distribution on the denture compared with model A. PMID:24779949

  8. Digital image correlation analysis of the load transfer by implant-supported restorations.

    PubMed

    Tiossi, Rodrigo; Lin, Lianshan; Rodrigues, Renata C S; Heo, Young C; Conrad, Heather J; de Mattos, Maria da Gloria C; Ribeiro, Ricardo F; Fok, Alex S L

    2011-04-01

    This study compared splinted and non-splinted implant-supported prosthesis with and without a distal proximal contact using a digital image correlation method. An epoxy resin model was made with acrylic resin replicas of a mandibular first premolar and second molar and with threaded implants replacing the second premolar and first molar. Splinted and non-splinted metal-ceramic screw-retained crowns were fabricated and loaded with and without the presence of the second molar. A single-camera measuring system was used to record the in-plane deformation on the model surface at a frequency of 1.0Hz under a load from 0 to 250N. The images were then analyzed with specialist software to determine the direct (horizontal) and shear strains along the model. Not splinting the crowns resulted in higher stress transfer to the supporting implants when the second molar replica was absent. The presence of a second molar and an effective interproximal contact contributed to lower stress transfer to the supporting structures even for non-splinted restorations. Shear strains were higher in the region between the molars when the second molar was absent, regardless of splinting. The opposite was found for the region between the implants, which had higher shear strain values when the second molar was present. When an effective distal contact is absent, non-splinted implant-supported restorations introduce higher direct strains to the supporting structures under loading. Shear strains appear to be dependent also on the region within the model, with different regions showing different trends in strain changes in the absence of an effective distal contact. PMID:21377159

  9. Photoelastic analysis of cemented or screwed implant-supported prostheses with different prosthetic connections.

    PubMed

    Tonella, Bianca Piccolotto; Pellizzer, Eduardo Piza; Ferraço, Renato; Falcón-Antenucci, Rosse Mary; Carvalho, Paulo S Perri de; Goiato, Marcelo Coelho

    2011-08-01

    The aim of this study was to evaluate the stress distribution of different retention systems (screwed or cemented) associated with different prosthetic connections (external hexagon, internal hexagon, and Morse taper) in 3-unit implant-supported fixed partial dentures through photoelasticity. Six models were fabricated with photoelastic resin PL-2, and each model contained two implants of 4.0 × 10.0 mm. The models presented different retention systems (screwed and cemented) and different connections (external hexagon, internal hexagon, and Morse taper). The prostheses were standardized and fabricated in Ni-Cr alloy. A circular polariscope was used and axial and oblique (45°) loads of 100 N were applied in a universal testing machine. The results were photographed and analyzed qualitatively with a graphic software (Adobe Photoshop). The screwed retention system exhibited higher number of fringes for both axial and oblique loadings. The internal hexagon implant presented better and lower stress distribution for both cemented and screwed prostheses. The oblique loading increased the number of fringes in all models tested. The cemented retention system presented better stress distribution. The internal hexagon implant was more favorable according to the biomechanical standpoint. The oblique load increased stress in all systems and connections tested. PMID:21851260

  10. Photoelastic Analysis on Different Retention Methods of Implant-Supported Prosthesis.

    PubMed

    Pimentel, Angélica Castro; Manzi, Marcello Roberto; Polo, Cristiane Ibanhês; Sendyk, Claudio Luiz; da Graça Naclério-Homem, Maria; Sendyk, Wilson Roberto

    2015-06-01

    The aim of this study was to evaluate the stress distribution of different retention systems (screwed, cemented, and mixed) in 5-unit implant-supported fixed partial dentures through the photoelasticity method. Twenty standardized titanium suprastructures were manufactured, of which 5 were screw retained, 5 were cement retained, and 10 were mixed (with an alternating sequence of abutments), each supported by 5 external hexagon (4.0 mm × 11.5 mm) implants. A circular polariscope was used, and an axial compressive load of 100 N was applied on a universal testing machine. The results were photographed and qualitatively analyzed. We observed the formation of isochromatic fringes as a result of the stresses generated around the implant after installation of the different suprastructures and after the application of a compressive axial load of 100 N. We conclude that a lack of passive adaptation was observed in all suprastructures with the formation of low-magnitude stress in some implants. When cemented and mixed suprastructures were subjected to a compressive load, they displayed lower levels of stress distribution and lower intensity fringes compared to the screwed prosthesis. PMID:25198152

  11. Photoelastic Stress Analysis Surrounding Implant-Supported Prosthesis and Alveolar Ridge on Mandibular Overdentures

    PubMed Central

    da Silva, Dorival Pedroso; Cazal, Claudia; de Almeida, Fernanda Campos Sousa; Dias, Reinaldo Brito e; Ballester, Rafael Yagüe

    2010-01-01

    The purpose of this research was to evaluate the maximum stress around osseointegrated implants and alveolar ridge, in a mandible with left partial resection through a photoelastic mandibular model. The first group consisted of two implants: traditional model (T), implants placed in the position of both canines; fulcrum model (F), implants placed in the position of left canine CL and right lateral incisor LiR. Both models linked through a bar and clips. The second group was consisted of three implants, with implants placed in the position of both canines (CR and CL) and the right lateral incisor (LiR), which composed four groups: (1) model with 3 “O” rings, (2) model 2 ERAs, bar with clips, (3) model 2 ERAs bar without clips; (4) model “O” ring bar and ERA. An axial and an oblique load of 6.8 kgf was applied on a overdenture at the 1st Pm, 2nd Pm, and 1st M. Results showed that the area around the left canine (CL) was practically free of stress; the left lateral incisor (LiL) developed only small tensions, and low stress in all the other cases; the right canine tooth suffered the largest concentrations of stress, mainly with the ERA retention mechanism. PMID:20467562

  12. A two-short-implant-supported molar restoration in atrophic posterior maxilla: A finite element analysis

    PubMed Central

    2016-01-01

    PURPOSE The aim of this study was to investigate the stress distribution of 2-short implants (2SIs) installed in a severely atrophic maxillary molar site. MATERIALS AND METHODS Three different diameters of internal connection implants were modeled: narrow platform (NP), regular platform (RP), and wide platform (WP). The maxillary first molars were restored with one implant or two short implants. Three 2SI models (NP-oblique, NP-vertical, and NP-horizontal) and four single implant models (RP and WP in a centered or cantilevered position) were used. Axial and oblique loadings were applied on the occlusal surface of the crown. The von Mises stress values were measured at the bone-implant, peri-implant bone, and implant/abutment complex. RESULTS The highest stress distribution at the bone-implant interface and the peri-implant bone was noticed in the RP group, and the lowest stress distribution was observed in the 2SI groups. Cantilevered position showed unfavorable stress distribution with axial loading. 2SI types did not affect the stress distribution in oblique loading. The number and installation positions of the implant, rather than the bone level, influenced the stress distribution of 2SIs. The implant/abutment complex of WP presented the highest stress concentration while that of 2SIs showed the lowest stress concentration. CONCLUSION 2SIs may be useful for achieving stable stress distribution on the surrounding bone and implant-abutment complex in the atrophic posterior maxilla. PMID:27555900

  13. Stress distribution patterns of implant supported overdentures-analog versus finite element analysis: A comparative in-vitro study

    PubMed Central

    Satpathy, Soumyadev; Babu, C. L. Satish; Shetty, Shilpa; Raj, Bharat

    2015-01-01

    Aims and Objectives: The aim of this study was to asses & compare the load transfer characteristics of Ball/O-ring and Bar/Clip attachment systems in implant supported overdentures using analog and finite element analysis models. Methodology: For the analog part of the study, castable bar was used for the bar and clip attachment and a metallic housing with a rubber O-ring component was used for the ball/O-ring attachment. The stress on the implant surface was measured using the strain-gauge technique. For the finite element analysis, the model were fabricated and load applications were done in a similar manner as in analog study. Results: The difference between both the attachment systems was found to be statistically significant (P<0.001). Conclusion: Ball/O-ring attachment system transmitted lesser amount of stresses to the implants on the non-loading side, as compared to the Bar-Clip attachment system. When overall stress distribution is compared, the Bar-Clip attachment seems to perform better than the Ball/O-ring attachment, because the force was distributed better. PMID:26929521

  14. Force Transfer and Stress Distribution in an Implant-Supported Overdenture Retained with a Hader Bar Attachment: A Finite Element Analysis

    PubMed Central

    Satheesh Kumar, Preeti; Satheesh, Kumar K. S.; John, Jins; Patil, Geetha; Patel, Ruchi

    2013-01-01

    Background and Objectives. A key factor for the long-term function of a dental implant is the manner in which stresses are transferred to the surrounding bone. The effect of adding a stiffener to the tissue side of the Hader bar helps to reduce the transmission of the stresses to the alveolar bone. But the ideal thickness of the stiffener to be attached to the bar is a subject of much debate. This study aims to analyze the force transfer and stress distribution of an implant-supported overdenture with a Hader bar attachment. The stiffener of the bar attachments was varied and the stress distribution to the bone around the implant was studied. Methods. A CT scan of edentulous mandible was used and three models with 1, 2, and 3 mm thick stiffeners were created and subjected to loads of emulating the masticatory forces. These different models were analyzed by the Finite Element Software (Ansys, Version 8.0) using von Mises stress analysis. Results. The results showed that the maximum stress concentration was seen in the neck of the implant for models A and B. In model C the maximum stress concentration was in the bar attachment making it the model with the best stress distribution, as far as implant failures are concerned. Conclusion. The implant with Hader bar attachment with a 3 mm stiffener is the best in terms of stress distribution, where the stress is concentrated at the bar and stiffener regions. PMID:24459589

  15. Three-Dimensional Finite Element Analysis of Anterior Single Implant-Supported Prostheses with Different Bone Anchorages

    PubMed Central

    Verri, Fellippo Ramos; Santiago Júnior, Joel Ferreira; Almeida, Daniel Augusto de Faria; Verri, Ana Caroline Gonçales; de Souza Batista, Victor Eduardo; Lemos, Cleidiel Aparecido Araujo; Noritomi, Pedro Yoshito; Pellizzer, Eduardo Piza

    2015-01-01

    The aim of this study was to evaluate the stress distribution of monocortical and bicortical implant placement of external hexagon connection in the anterior region of the maxilla by 3D finite element analysis (FEA). 3D models were simulated to represent a bone block of anterior region of the maxilla containing an implant (4.0 × 10.0 mm) and an implant-supported cemented metalloceramic crown of the central incisor. Different techniques were tested (monocortical, bicortical, and bicortical associated with nasal floor elevation). FEA was performed in FEMAP/NeiNastran software using loads of 178 N at 0°, 30°, and 60° in relation to implant long axis. The von Mises, maximum principal stress, and displacement maps were plotted for evaluation. Similar stress patterns were observed for all models. Oblique loads increased the stress concentration on fixation screws and in the cervical area of the implants and bone around them. Bicortical technique showed less movement tendency in the implant and its components. Cortical bone of apical region showed increase of stress concentration for bicortical techniques. Within the limitations of this study, oblique loading increased the stress concentrations for all techniques. Moreover, bicortical techniques showed the best biomechanical behavior compared with monocortical technique in the anterior maxillary area. PMID:26351654

  16. Meta-analysis of Failure and Survival Rate of Implant-supported Single Crowns, Fixed Partial Denture, and Implant Tooth-supported Prostheses

    PubMed Central

    Muddugangadhar, B C; Amarnath, G S; Sonika, Radhika; Chheda, Pratik S; Garg, Ashu

    2015-01-01

    Background: Dental implants have become the most viable option for rehabilitation. Although, many studies report the success of these reconstructions using implants, a cumulative data about the various studies and the failure rate still remain unaddressed. Therefore, the purpose of this systematic review was to analyze these data and to derive the cumulative survival rate of different implant-supported prosthesis. Materials and Methods: Manual searches followed by a MEDLINE search were conducted to select prospective and retrospective cohort studies on single crowns (SCs), fixed partial denture (FPD), and tooth implant connected prostheses with a mean follow-up time of minimum of 5 years. Random-effects Poisson’s regression models have been used to obtain summary estimates for implant failure and survival rates. Results: Data were extracted from the final selected 63 studies. In a meta-analysis of these studies, the survival rate of SCs supported by implants (95% CI) was 96.363%, for FPDs was 94.525% and implant tooth-supported prostheses was 91.27% after 5 years of function. The cumulative failure rate per 100 FPD years of the SCs, FPDs, and implant tooth-supported prostheses were 0.684, 0.881, and 1.514, respectively. Conclusion: The study concludes high survival rates for implant-supported SCs followed by implant-supported FPDs can be expected over an observation period of 5 years. However, tooth implant-supported prostheses can be provided if there are certain limitations prohibiting the completely implant-supported prostheses. PMID:26435609

  17. Passivity versus unilateral angular misfit: evaluation of stress distribution on implant-supported single crowns: three-dimensional finite element analysis.

    PubMed

    Gomes, Erica Alves; Assunção, Wirley Gonçalves; Barão, Valentim Adelino Ricardo; Delben, Juliana Aparecida; Rocha, Eduardo Passos; de Sousa, Edson Antonio Capello

    2010-11-01

    The aim of this study was to evaluate the effect of unilateral angular misfit of 100 μm on stress distribution of implant-supported single crowns with ceramic veneering and gold framework by three-dimensional finite element analysis. Two three-dimensional models representing a maxillary section of premolar region were constructed: group 1 (control)-crown completely adapted to the implant and group 2-crown with unilateral angular misfit of 100 μm. A vertical force of 100 N was applied on 2 centric points of the crown. The von Mises stress was used as an analysis criterion. The stress values and distribution in the main maps (204.4 MPa for group 1 and 205.0 MPa for group 2) and in the other structures (aesthetic veneering, framework, retention screw, implant, and bone tissue) were similar for both groups. The highest stress values were observed between the first and second threads of the retention screw. Considering the bone tissue, the highest stress values were exhibited in the peri-implant cortical bone. The unilateral angular misfit of 100 μm did not influence the stress distribution on the implant-supported prosthesis under static loading. PMID:21119400

  18. A finite element analysis of stress distribution in the bone, around the implant supporting a mandibular overdenture with ball/o ring and magnetic attachment.

    PubMed

    John, Jins; Rangarajan, V; Savadi, Ravindra C; Satheesh Kumar, K S; Satheesh Kumar, Preeti

    2012-03-01

    Today implant dentistry has made great inroads into the treatment modalities that are available in treating an edentulous patient. Popularity of a two implant retained overdenture has created a necessity to examine the various attachment systems being used and the stresses that are transmitted to the alveolar bone. Hence a Three dimensional Finite Element Analysis was done to analyze the stress distribution in the mandibular bone with implant-supported overdenture having Ball/O-ring and Magnet attachments of different diameters. A segment of the anterior region of the mandible was modeled with implant and the overdenture. Four different models were generated having Ball/O-Ring and Magnet Attachments. Forces of 10 N, 35 N and 70 N were applied from the horizontal, vertical and oblique directions respectively and the stress distribution studied. It was concluded that the greatest stress concentrations were seen at the crest of the cortical bone and could be reduced by using smaller sized attachments for implant supported-overdenture. PMID:23450217

  19. Stress distribution on a three-unit implant-supported zirconia framework. A 3D finite element analysis and fatigue test

    PubMed Central

    SANNINO, G.; POZZI, A.; SCHIAVETTI, R.; BARLATTANI, A.

    2012-01-01

    SUMMARY Purpose The purpose of this study was to investigate, by finite element analysis (FEA) and fatigue analysis, the influence of different loading conditions on the stress distribution in a 3-unit implant-supported Y-TZP fixed partial denture (FPD). Material and methods A three-dimensional FEM model was developed. The materials used in this study were assumed to be linearly elastic, homogeneous and isotropic. 100 N and 300 N loads over a 0,5 mm2 areas with different angles (0°, 15° and 35°) and locations were applied on the prosthesis and the distribution of equivalent von Mises stress was investigated. A fatigue analysis was carried out too. Results Maximum stresses were found at the connector region of the framework when the intermediate element is loaded (100 N load pattern: 32,9 MPa, 33 MPa and 51,8 MPa; 300 N load pattern: 98,6 MPa, 102,8 MPa and 155,7 MPa, respectively with 0°, 15° and 35° of inclination). Results confirmed the vulnerability of both connector areas even if just one pillar was loaded with an increase in stress when angle of load inclination is larger. The cyclic fatigue evaluation indicates a strong propensity for fatigue behavior, presenting a considerable range of loading conditions. No fracture fatigue occurred with a 100 N force. A 300 N force applied to the pontic produces no fatigue problems because the load is equally shared by whole system. A 300 N force applied to one of the two pillars, or to both implants generates fatigue problems. Conclusion F.E.M. analysis of a 3-unit implant-supported Y-TZPFPD, give accurate information about loading conditions for clinical success over time. Fatigue analysis results show structural reliability of the Y-TZP as framework material for 3-unit posterior FPDs. PMID:23285401

  20. Stress analysis of a fixed implant-supported denture by the finite element method (FEM) when varying the number of teeth used as abutments

    PubMed Central

    LANZA, Marcos Daniel Septímio; SERAIDARIAN, Paulo Isaías; JANSEN, Wellington Correa; LANZA, Marcos Dias

    2011-01-01

    Objectives In some clinical situations, dentists come across partially edentulous patients, and it might be necessary to connect teeth to implants. The aim of this study was to evaluate a metal-ceramic fixed tooth/implant-supported denture with a straight segment, located in the posterior region of the maxilla, when varying the number of teeth used as abutments. Materials and Methods A three-element fixed denture composed of one tooth and one implant (Model 1), and a four-element fixed denture composed of two teeth and one implant (Model 2) were modeled. A 100 N load was applied, distributed uniformly on the entire set, simulating functional mastication, for further analysis of the SEQV (Von Mises) principal stresses, which were compared with the flow limit of the materials. Results In a quantitative analysis, it may be observed that in the denture with one tooth, the maximum SEQV stress was 47.84 MPa, whereas for the denture with two teeth the maximum SEQV stress was 35.82 MPa, both located in the region between the pontic and the tooth. Conclusion Lower stresses were observed in the denture with an additional tooth. Based on the flow limit of the materials, porcelain showed values below the limit of functional mastication. PMID:22231003

  1. Axial loads on implant-supported partial fixed prostheses for external and internal hex connections and machined and plastic copings: strain gauge analysis.

    PubMed

    de Vasconcellos, Luis Gustavo Oliveira; Kojima, Alberto Noriyuki; Nishioka, Renato Sussumu; de Vasconcellos, Luana Marotta Reis; Balducci, Ivan

    2015-04-01

    The aim of this in vitro study was to use strain gauge (SG) analysis to compare the effects of the implant-abutment joint, the coping, and the location of load on strain distribution in the bone around implants supporting 3-unit fixed partial prostheses. Three external hexagon (EH) implants and 3 internal hexagon (IH) implants were inserted into 2 polyurethane blocks. Microunit abutments were screwed onto their respective implant groups. Machined cobalt-chromium copings and plastic copings were screwed onto the abutments, which received standard wax patterns. The wax patterns were cast in a cobalt-chromium alloy (n = 5): group 1 = EH/machined. group 2 = EH/plastic, group 3 = IH/machined, and group 4 = IH/plastic. Four SGs were bonded onto the surface of the block tangentially to the implants. Each metallic structure was screwed onto the abutments and an axial load of 30 kg was applied at 5 predetermined points. The magnitude of microstrain on each SG was recorded in units of microstrain (με). The data were analyzed using 3-factor repeated measures analysis of variance and a Tukey test (α = 0.05). The results showed statistically significant differences for the type of implant-abutment joint, loading point, and interaction at the implant-abutment joint/loading point. The IH connection showed higher microstrain values than the EH connection. It was concluded that the type of coping did not interfere in the magnitude of microstrain, but the implant/abutment joint and axial loading location influenced this magnitude. PMID:23574373

  2. Effect of the Number of Implants on Stress Distribution of Anterior Implant-Supported Fixed Prostheses Combined with a Removable Partial Denture: A Finite Element Analysis

    PubMed Central

    Mahshid, Minoo; Geramy, Allahyar; Ejlali, Massoud; Sedaghat Monfared, Majid; Rezvani Habib Abadi, Shirin

    2014-01-01

    Objective: The main goal of this study was to evaluate differences in stress distribution relevant to the number of implants under an anterior bridge when combined with a removable partial denture in the posterior region. Materials and Methods: Four three-dimensional finite element models (3D FEM) were designed from a mandible containing an implant-supported bridge extending between canines, and a bilateral distal extension removable partial denture. A nonrigid connection was selected as the attachment method between the partial denture and the anterior implant-supported fixed prosthesis; 2, 3, 4 and 5 implants supporting the bridge all with 10mm length and 3.8 mm diameter were assessed. With the aid of the finite element program ANSYS 8.0, the models were loaded and von Mises stresses were evaluated. Results: In spongy bone, stress forces showed a decrease from 2 implants to 4 implants but showed an increase in the 5-implant model. Stresses on cortical bone of terminal implants were in similar range in the 2-, 3- and 4-implant models. While, in the 5-implant model the amount of stresses on terminal implants increased dramatically. The stresses on implants were nearly similar in all models, with the greatest amount on terminal implants. Conclusion: Within the limitations of this study, 2-, 3- and 4-implant models showed less stress on cortical and spongy bone in comparison with the 5-implant model. The stresses transferred to implants were nearly similar. PMID:25628669

  3. Mastication Improvement After Partial Implant-supported Prosthesis Use

    PubMed Central

    Gonçalves, T.M.S.V.; Campos, C.H.; Gonçalves, G.M.; de Moraes, M.; Rodrigues Garcia, R.C.M.

    2013-01-01

    Partially edentulous patients may be rehabilitated by the placement of removable dental prostheses, implant-supported removable dental prostheses, or partial implant fixed dental prostheses. However, it is unclear the impact of each prosthesis type over the masticatory aspects, which represents the objective of this paired clinical trial. Twelve patients sequentially received and used each of these 3 prosthesis types for 2 months, after which maximum bite force was assessed by a strain sensor and food comminution index was determined with the sieving method. Masseter and temporal muscle thicknesses during rest and maximal clenching were also evaluated by ultrasonography. Each maxillary arch received a new complete denture that was used throughout the study. Data were analyzed by analysis of variance for repeated measures, followed by the Tukey test (p < .05). Maximum bite force and food comminution index increased (p < .0001) after implant-supported dental prosthesis and implant fixed dental prosthesis use, with the higher improvement found after the latter’s use. Regardless of implant-retained prosthesis type, masseter muscle thickness during maximal clenching also increased (p < .05) after implant insertion. Partial implant-supported prostheses significantly improved masseter muscle thickness and mastication, and the magnitude of this effect was related to prosthesis type (International Clinical Trial Registration RBR-9J26XD). PMID:24158344

  4. Comparison of different designs of implant-retained overdentures and fixed full-arch implant-supported prosthesis on stress distribution in edentulous mandible--a computed tomography-based three-dimensional finite element analysis.

    PubMed

    Barão, V A R; Delben, J A; Lima, J; Cabral, T; Assunção, W G

    2013-04-26

    A finite element analysis was used to compare the effect of different designs of implant-retained overdentures and fixed full-arch implant-supported prosthesis on stress distribution in edentulous mandible. Four models of an human mandible were constructed. In the OR (O'ring) group, the mandible was restored with an overdenture retained by four unsplinted implants with O'ring attachment; in the BC (bar-clip) -C and BC groups, the mandibles were restored with overdentures retained by four splinted implants with bar-clip anchor associated or not with two distally placed cantilevers, respectively; in the FD (fixed denture) group, the mandible was restored with a fixed full-arch four-implant-supported prosthesis. Models were supported by the masticatory muscles and temporomandibular joints. A 100-N oblique load was applied on the left first molar. Von Mises (σvM), maximum (σmax) and minimum (σmin) principal stresses (in MPa) analyses were obtained. BC-C group exhibited the highest stress values (σvM=398.8, σmax=580.5 and σmin=-455.2) while FD group showed the lowest one (σvM=128.9, σmax=185.9 and σmin=-172.1). Within overdenture groups, the use of unsplinted implants reduced the stress level in the implant/prosthetic components (59.4% for σvM, 66.2% for σmax and 57.7% for σmin versus BC-C group) and supporting tissues (maximum stress reduction of 72% and 79.5% for σmax, and 15.7% and 85.7% for σmin on the cortical and trabecular bones, respectively). Cortical bone exhibited greater stress concentration than the trabecular bone for all groups. The use of fixed implant dentures and removable dentures retained by unsplinted implants to rehabilitate edentulous mandible reduced the stresses in the periimplant bone tissue, mucosa and implant/prosthetic components. PMID:23518207

  5. A finite element study on stress distribution of two different attachment designs under implant supported overdenture

    PubMed Central

    El-Anwar, Mohamed I.; Yousief, Salah A.; Soliman, Tarek A.; Saleh, Mahmoud M.; Omar, Wael S.

    2015-01-01

    Objective This study aimed to evaluate stress patterns generated within implant-supported mandibular overdentures retained by two different attachment types: ball and socket and locator attachments. Materials and methods Commercial CAD/CAM and finite element analysis software packages were utilized to construct two 3D finite element models for the two attachment types. Unilateral masticatory compressive loads of 50, 100, and 150 N were applied vertically to the overdentures, parallel to the longitudinal axes of the implants. Loads were directed toward the central fossa in the molar region of each overdenture, that linear static analysis was carried out to find the generated stresses and deformation on each part of the studied model. Results According to FEA results the ball attachment neck is highly stressed in comparison to the locator one. On the other hand mucosa and cortical bone received less stresses under ball and socket attachment. Conclusions Locator and ball and socket attachments induce equivalent stresses on bone surrounding implants. Locator attachment performance was superior to that of the ball and socket attachment in the implants, nylon caps, and overdenture. Locator attachments are highly recommended and can increase the interval between successive maintenance sessions. PMID:26644755

  6. Effects of crown retrieval on implants and the surrounding bone: a finite element analysis

    PubMed Central

    Unal, Server Mutluay; Yurekli, Emel; Güven, Sedat

    2016-01-01

    PURPOSE The aim of this study was to observe stress concentration in the implant, the surrounding bone, and other components under the pull-out force during the crown removal. MATERIALS AND METHODS Two 3-dimensional models of implant-supported conventional metal ceramic crowns were digitally constructed. One model was designed as a vertically placed implant (3.7 mm × 10 mm) with a straight abutment, and the other model was designed as a 30-degree inclined implant (3.7 mm × 10 mm) with an angled abutment. A pull-out force of 40 N was applied to the crown. The stress values were calculated within the dental implant, the abutment, the abutment screw, and the surrounding bone. RESULTS The highest stress concentration was observed at the coronal portion of the straight implant (9.29 MPa). The stress concentrations at the cortical bone were lower than at the implants, and maximum stress concentration in bone structure was 1.73 MPa. At the abutment screws, the stress concentration levels were similiar (3.09 MPa and 3.44 MPa), but the localizations were different. The stress at the angled abutment was higher than the stress at the straight abutment. CONCLUSION The pull-out force, applied during a crown removal, did not show an evident effect in bone structure. The higher stress concentrations were mostly observed at the implant and the abutment collar. In addition, the abutment screw, which is the weakest part of an implant system, also showed stress concentrations. Implant angulation affected the stress concentration levels and localizations. CLINICAL IMPLICATIONS These results will help clinicians understand the mechanical behavior of cement-retained implant-supported crowns during crown retrieval. PMID:27141257

  7. Remote Sensing Efficiency for Urban Analysis of Mecca and Surrounds

    NASA Astrophysics Data System (ADS)

    Imam, Ayman; Alhaddad, Bahaa; Roca, Josep

    2016-06-01

    Situated in the southwest of Saudi Arabia, Mecca is considered the spiritual capital of one and a half billion worldwide Muslims. The city is visited by millions of pilgrims every year. It has undergone significant changes in land cover (LC) since the government first embarked on a series of ambitious development projects 20 years ago to accommodate the growing number of pilgrims and citizens. The main objective of our study is to detect, identify, analyze and measure the evolving land cover and urban morphology composition from multi-temporal satellite images. To characterize the morphological change during a period of twenty years, four satellite images, acquired in 1998 by Landsat TM and in 2003, 2008 and 2013 by Landsat ETM+, were classified into five main categories: Urban, Street, Soil and Vegetation. In addition, DEM has been extracted and included as Mountain. Change detection (CD) analysis is applied using post-classification comparison and GIS. As part of the study, morphological index, such as, Entropy is included for better understanding of urban structures behaviour. Mecca and its surroundings show a noticeable increase in urban and vegetation cover. Urban cover (UC) changes were divided into five radial directions: Northeast, Southeast, Southwest, East, and Northwest. These changes are influenced by mountain ranges surrounding the city and the highways. These revelations can play a significant role towards future planning and development activities, which may further promote urban growth.

  8. Comparative analysis of the fit of 3-unit implant-supported frameworks cast in nickel-chromium and cobalt-chromium alloys and commercially pure titanium after casting, laser welding, and simulated porcelain firings.

    PubMed

    Tiossi, Rodrigo; Rodrigues, Renata Cristina Silveira; de Mattos, Maria da Glória Chiarello; Ribeiro, Ricardo Faria

    2008-01-01

    This study compared the vertical misfit of 3-unit implant-supported nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloy and commercially pure titanium (cpTi) frameworks after casting as 1 piece, after sectioning and laser welding, and after simulated porcelain firings. The results on the tightened side showed no statistically significant differences. On the opposite side, statistically significant differences were found for Co-Cr alloy (118.64 microm [SD: 91.48] to 39.90 microm [SD: 27.13]) and cpTi (118.56 microm [51.35] to 27.87 microm [12.71]) when comparing 1-piece to laser-welded frameworks. With both sides tightened, only Co-Cr alloy showed statistically significant differences after laser welding. Ni-Cr alloy showed the lowest misfit values, though the differences were not statistically significantly different. Simulated porcelain firings revealed no significant differences. PMID:18546764

  9. Analysis of Ices Surrounding YSOs in Taurus and ρ Ophiuchi

    NASA Astrophysics Data System (ADS)

    Van Brunt, Kari A.; Pastorius, M. L.; Gibb, E. L.; Shenoy, S. S.

    2008-05-01

    Recent technological advances have sparked an exciting study of the chemistry in star forming regions. By combining Spitzer IRS and ground based observations, a more sensitive diagnostic of the composition of material surrounding Young Stellar Objects (YSOs) can be performed. Initial studies of the material around YSOs show significant differences in the composition of volatiles in regions with massive YSOs compared to regions containing low mass YSOs. Pontoppidan (2006) found that CO2 and CO abundances were enhanced toward the center of the cold Ophiuchus-F core, and recent results for the CO2 ice feature at 15.3 μm also imply spatial variations within regions of star formation. Analysis of short-lived radioisotopes in meteorites indicates our solar system was seeded with material from a nearby supernova, suggesting our system formed in a region of both high and low mass star formation (Goswami & Vanhala 2000). Here we present preliminary results from data taken with the Infrared Spectrometer (IRS) on the Spitzer Space Telescope and SpeX at the Infrared Telescope Facility (IRTF) located on Mauna Kea, HI. Observations of H2O ice, CO ice, and CO2 ice at 3.0 μm, 4.67 μm, and 15.3 μm, respectively, are presented for the Taurus and ρ Ophiuchi star forming regions. We measured abundances and used laboratory spectra to constrain the polar/apolar composition and the thermal history of the region. In the future, additional YSOs in the Taurus and ρ Ophiuchi regions will be similarly analyzed in order to correlate variations in the volatile composition of the material surrounding YSOs with environmental factors and evolutionary states.

  10. The clinical success of tooth- and implant-supported zirconia-based fixed dental prostheses. A systematic review.

    PubMed

    Le, M; Papia, E; Larsson, C

    2015-06-01

    The aim was to make an inventory of the current literature on the clinical performance of tooth- or implant-supported zirconia-based FDPs and analyse and discuss any complications. Electronic databases, PubMed.gov, Cochrane Library and Science Direct, were searched for original studies reporting on the clinical performance of tooth- or implant-supported zirconia-based FDPs. The electronic search was complemented by manual searches of the bibliographies of all retrieved full-text articles and reviews, as well as a hand search of the following journals: International Journal of Prosthodontics, Journal of Oral Rehabilitation, International Journal of Oral & Maxillofacial Implants and Clinical Oral Implants Research. The search yielded 4253 titles. Sixty-eight potentially relevant full-text articles were retrieved. After applying pre-established criteria, 27 studies were included. Twenty-three studies reported on tooth-supported and 4 on implant-supported FDPs. Five of the studies were randomised, comparing Y-TZP-based restorations with metal-ceramic or other all-ceramic restorations. Most tooth-supported FDPs were FDPs of 3-5 units, whereas most implant-supported FDPs were full arch. The majority of the studies reported on 3- to 5-year follow-up. Life table analysis revealed cumulative 5-year survival rates of 93.5% for tooth-supported and 100% for implant-supported FDPs. For tooth-supported FDPs, the most common reasons for failure were veneering material fractures, framework fractures and caries. Cumulative 5-year complication rates were 27.6% and 30.5% for tooth- and implant-supported FDPs, respectively. The most common complications were veneering material fractures for tooth- as well as implant-supported FDPs. Loss of retention occurred more frequently in FDPs luted with zinc phosphate or glass-ionomer cement compared to those luted with resin cements. The results suggest that the 5-year survival rate is excellent for implant-supported zirconia-based FDPs

  11. Simplified custom impression post for implant-supported restorations.

    PubMed

    Patras, Michael; Martin, William

    2016-05-01

    The esthetic outcome of an implant-supported restoration is greatly influenced by the relationship between the contours of the definitive prosthesis and the periimplant tissues. In this clinical technique, an implant analog holder and autopolymerizing acrylic resin were used to accurately register the soft-tissue transition zone created by the interim restoration and transfer it to the impression post during the definitive impression. PMID:26774317

  12. Biomechanical considerations on tooth-implant supported fixed partial dentures

    PubMed Central

    Calvani, Pasquale; Hirayama, Hiroshi

    2012-01-01

    This article discusses the connection of teeth to implants, in order to restore partial edentulism. The main problem arising from this connection is tooth intrusion, which can occur in up to 7.3% of the cases. The justification of this complication is being attempted through the perspective of biomechanics of the involved anatomical structures, that is, the periodontal ligament and the bone, as well as that of the teeth- and implant-supported fixed partial dentures. PMID:23255882

  13. Split-Framework in Mandibular Implant-Supported Prosthesis

    PubMed Central

    2015-01-01

    During oral rehabilitation of an edentulous patient with an implant-supported prosthesis, mandibular flexure must be considered an important biomechanical factor when planning the metal framework design, especially if implants are installed posterior to the interforaminal region. When an edentulous mandible is restored with a fixed implant-supported prosthesis connected by a fixed full-arch framework, mandibular flexure may cause needless stress in the overall restorative system and lead to screw loosening, poor fit of prosthesis, loss of the posterior implant, and patient's discomfort due to deformation properties of the mandible during functional movements. The use of a split-framework could decrease the stress with a precise and passive fit on the implants and restore a more natural functional condition of the mandible, helping in the longevity of the prosthesis. Therefore, the present clinical report describes the oral rehabilitation of an edentulous patient by a mandibular fixed implant-supported prosthesis with a split-framework to compensate for mandibular flexure. Clinical Significance. The present clinical report shows that the use of a split-framework reduced the risk of loss of the posterior implants or screws loosening with acceptable patient comfort over the period of a year. The split-framework might have compensated for the mandibular flexure during functional activities. PMID:26770841

  14. Fluid Production Induced Stress Analysis Surrounding an Elliptic Fracture

    NASA Astrophysics Data System (ADS)

    Pandit, Harshad Rajendra

    Hydraulic fracturing is an effective technique used in well stimulation to increase petroleum well production. A combination of multi-stage hydraulic fracturing and horizontal drilling has led to the recent boom in shale gas production which has changed the energy landscape of North America. During the fracking process, highly pressurized mixture of water and proppants (sand and chemicals) is injected into to a crack, which fractures the surrounding rock structure and proppants help in keeping the fracture open. Over a longer period, however, these fractures tend to close due to the difference between the compressive stress exerted by the reservoir on the fracture and the fluid pressure inside the fracture. During production, fluid pressure inside the fracture is reduced further which can accelerate the closure of a fracture. In this thesis, we study the stress distribution around a hydraulic fracture caused by fluid production. It is shown that fluid flow can induce a very high hoop stress near the fracture tip. As the pressure gradient increases stress concentration increases. If a fracture is very thin, the flow induced stress along the fracture decreases, but the stress concentration at the fracture tip increases and become unbounded for an infinitely thin fracture. The result from the present study can be used for studying the fracture closure problem, and ultimately this in turn can lead to the development of better proppants so that prolific well production can be sustained for a long period of time.

  15. Impact of fixed implant supported prostheses in edentulous patients: protocol for a systematic review

    PubMed Central

    López, Carolina S; Saka, Constanza H; Rada, Gabriel; Valenzuela, Daniela D

    2016-01-01

    Introduction Edentulism is a debilitating and irreversible condition described as the ‘final marker of disease burden for oral health’. Therapy with dental implants is being used on a large scale to replace missing teeth and to rehabilitate edentulous patients with overdentures and implant supported fixed dentures as a method of solving the problem of instability and lack of retention associated with conventional removable prostheses. Fixed implant supported prostheses are an alternative for implant rehabilitation treatment that allow patients to have new fixed teeth. They can be indicated in partial or total edentulous patients, and they can replace single teeth, or teeth and supporting tissues (hybrid prosthesis). They overcome the limitations of conventional dentures, increasing stability and retention, providing functional and psychological advantages for the patients. Methods and analysis We will electronically search for randomised controlled trials evaluating the effects of fixed implant supported prostheses in edentulous patients in the following databases: Pubmed/MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials. We will also try to obtain literature screening references of included studies, searching for trial protocols in the WHO International Clinical Trials Registry Platform, reviewing International Team for Implantology conference proceedings and searching for non-published studies through Open Gray. Two researchers will independently undertake selection of studies, data extraction and assessment of the quality of the included studies. Data synthesis and subgroup analyses will be performed using special Review Manager software. Data will be combined in a meta-analysis using a random effects model. Results The results will be presented as risk ratios for dichotomous data, and as mean difference or standardised mean difference for continuous data. Ethics and dissemination No ethics approval is considered necessary. The results

  16. Bone's responses to different designs of implant-supported fixed partial dentures.

    PubMed

    Rungsiyakull, Chaiy; Chen, Junning; Rungsiyakull, Pimduen; Li, Wei; Swain, Michael; Li, Qing

    2015-04-01

    This paper explores the biomechanics and associated bone remodeling responses of two different abutment configurations, namely implant-implant-supported versus tooth-implant-supported fixed partial dentures. Two 3D finite element analysis models are created based upon computerized tomography data. The strain energy density induced by occlusal loading is used as a mechanical stimulus for driving the bone remodeling. To measure osseointegration and stability during healing, a resonance frequency analysis is conducted. At the second premolar peri-implant region, overloading resorption around the neck of implant is identified in both the models over the first 12 months. Stress-shielding around the edentulous region is also observed in both the models with a greater resorption rate found in the implant-implant case. The remodeling and resonance frequency analyses reveal that the tooth-implant scheme offers a higher degree of osseointegration. The remodeling procedure is expected to provide prosthodontists with a modeling tool to assess possible long-term clinical outcomes. PMID:25209424

  17. Quadruple zygomatic implants supported rehabilitation in failed maxillary bone reconstruction.

    PubMed

    Nocini, Pier Francesco; Trevisiol, Lorenzo; D'Agostino, Antonio; Zanette, Giovanni; Favero, Vittorio; Procacci, Pasquale

    2016-09-01

    Extreme atrophy of the jaws constitutes a challenge for maxillofacial surgeons. The technique involving Le Fort I osteotomy, bone grafting, and endosseous implants remains the gold standard treatment for class V and class VI atrophy of the maxilla. As severe maxillary atrophy is associated to impaired microvascularization of overlying soft tissues, reconstruction using vascularized free fibula flaps together with endosseous implants is one of the possible treatment plans. When this approach fails, however, retreating these patients using traditional techniques often proves unsatisfactory. This study outlines our clinical experience with full-arch zygoma implant-supported prosthetic rehabilitation to treat severe atrophic maxilla following failure of strategies including multiple Le Fort I procedures or vascularized free fibular flaps. PMID:26911802

  18. Implant-supported overdentures: the ZAAG attachment system.

    PubMed

    Davidoff, S R

    1997-11-01

    It has been amply demonstrated during the last decade that there are significant advantages to implant-supported overdentures beyond conventional complete dentures. Several attachment systems exist for connecting the overdenture to the implants, and practically all of them present notable benefits to the patients. This article discusses the use of the Zest Anchor Advanced Generation (ZAAG). This system, an outgrowth from the original Zest attachment, uses both individual implant attachments and bar attachments, and is compatible with all major implant systems. In addition to the retention, stability, and resiliency the ZAAG implant attachment system provides, it has the advantage of placing the resistance force of the attachment close to the implant body. PMID:9533347

  19. Effect of veneering material on the deformation suffered by implant-supported fixed prosthesis framework

    PubMed Central

    GRANDO, Antônio Francisco; REZENDE, Carlos Eduardo Edwards; SOUSA, Edson Antônio Capello; RUBO, José Henrique

    2014-01-01

    Knowing how stresses are dissipated on the fixed implant-supported complex allows adequate treatment planning and better choice of the materials used for prosthesis fabrication. Objectives The aim of this study was to evaluate the deformation suffered by cantilevered implant-supported fixed prostheses frameworks cast in silver-palladium alloy and coated with two occlusal veneering materials: acrylic resin or porcelain. Material and Methods Two strain gauges were bonded to the inferior surface of the silver-palladium framework and two other were bonded to the occlusal surface of the prosthesis framework covered with ceramic and acrylic resin on each of its two halves. The framework was fixed to a metallic master model and a 35.2 N compression force was applied to the cantilever at 10, 15 and 20 mm from the most distal implant. The measurements of deformation by compression and tension were obtained. The statistical 2-way ANOVA test was used for individual analysis of the experiment variables and the Tukey test was used for the interrelation between all the variables (material and distance of force application). Results The results showed that both variables had influence on the studied factors (deformation by compression and tension). Conclusion The ceramic coating provided greater rigidity to the assembly and therefore less distortion compared with the uncoated framework and with the resin-coated framework. The cantilever arm length also influenced the prosthesis rigidity, causing higher deformation the farther the load was applied from the last implant. PMID:25025562

  20. A Sequential Approach to Implant-Supported Overdentures.

    PubMed

    Kosinski, Timothy

    2016-03-01

    Fabrication of implant-supported maxillary or mandibular overdentures can seem to be difficult procedures. Many things could go wrong and/or unnoticed until the fabrication has been completed. Implants must be correctly surgically placed in viable bone at the proper angulation and spacing within an arch. The type of attachment must be considered and future treatment of the appliance should be simple and efficient. The appliance must function not only initially but also for many years to come. The author has found the use of the GPS attachment to be an ideal tool to achieve the goals of retention and stability. Careful planning is the most important part of this process, and understanding the benefits and risks of creating overdentures should be well understood by the dentists. By sequentially planning and treating these types of cases, the patient is able to function reasonably during the stages of implant healing. The final prosthesis is created and remaining teeth that held the transitional appliance in place are remove on the day of final seating. This is an excellent simplified retentive system option for those patients who are anxious about losing their teeth, even those teeth that are diseased and ugly. PMID:27039540

  1. Analysis of the geomorphology surrounding the Chang'e-3 landing site

    NASA Astrophysics Data System (ADS)

    Li, Chun-Lai; Mu, Ling-Li; Zou, Xiao-Duan; Liu, Jian-Jun; Ren, Xin; Zeng, Xing-Guo; Yang, Yi-Man; Zhang, Zhou-Bin; Liu, Yu-Xuan; Zuo, Wei; Li, Han

    2014-12-01

    Chang'e-3 (CE-3) landed on the Mare Imbrium basin in the east part of Sinus Iridum (19.51°W, 44.12°N), which was China's first soft landing on the Moon and it started collecting data on the lunar surface environment. To better understand the environment of this region, this paper utilizes the available high-resolution topography data, image data and geological data to carry out a detailed analysis and research on the area surrounding the landing site (Sinus Iridum and 45 km×70 km of the landing area) as well as on the topography, landform, geology and lunar dust of the area surrounding the landing site. A general topographic analysis of the surrounding area is based on a digital elevation model and digital elevation model data acquired by Chang'e-2 that have high resolution; the geology analysis is based on lunar geological data published by USGS; the study on topographic factors and distribution of craters and rocks in the surrounding area covering 4 km×4 km or even smaller is based on images from the CE-3 landing camera and images from the topographic camera; an analysis is done of the effect of the CE-3 engine plume on the lunar surface by comparing images before and after the landing using data from the landing camera. A comprehensive analysis of the results shows that the landing site and its surrounding area are identified as typical lunar mare with flat topography. They are suitable for maneuvers by the rover, and are rich in geological phenomena and scientific targets, making it an ideal site for exploration.

  2. Neutron activation analysis of thermal power plant ash and surrounding area soils.

    PubMed

    Al-Masri, M S; Haddad, Kh; Alsomel, N; Sarhil, A

    2015-08-01

    Elemental concentrations of As, Cd, Co, Cr, Fe, Hg, Mo, Ni, Se, and Zn have been determined in fly and bottom ash collected from Syrian power plants fired by heavy oil and natural gas using instrumental neutron activation analysis. The results showed that all elements were more concentrated in fly ash than in the fly ash; there was a clear increasing trend of the elemental concentrations in the fly ash along the flue gas pathway. The annual emission of elements was estimated. Elemental concentrations were higher inside the campus area than in surrounding areas, and the lowest values were found in natural-gas-fired power plant. In addition, the levels have decreased as the distance from power plant campus increases. However, the levels in the surrounding villages were within the Syrian standard for agriculture soil. PMID:26220782

  3. Nuclear microbeam analysis of wear particles in tissue surrounding failed hip joint implants

    NASA Astrophysics Data System (ADS)

    Grime, G. W.; Triffitt, J. T.; Williamson, M. C.; Athanasou, N. A.

    1994-05-01

    Particulate wear debris from hip joint replacements is an important factor in determining the response of the surrounding tissue to the implants. Failed replacement joints are surrounded by a layer of fibrous tissue showing an inflammatory response to the wear debris. This reaction leads to bone resorption and the eventual failure of the prosthesis. In preliminary experiments the Oxford scanning proton microprobe has been used to study the composition of wear particles in the membranes surrounding failed implants constructed from Ti/V/Al alloy. The membranes were observed to contain 1-10 μm particles with major constituents from the alloy and also from the cement and polyethylene used in the fitting and construction of the implant. Histological staining shows that these particles are associated with areas of high macrophage activity. Individual PIXE analysis of the metal particles indicates that two populations (high Ti/low Al and low Ti/high Al) may be present. These observations will provide further information on the mechanisms of implant degradation.

  4. Comparison of immediate complete denture, tooth and implant-supported overdenture on vertical dimension and muscle activity

    PubMed Central

    Shah, Farhan Khalid; Gebreel, Ashraf; Elshokouki, Ali hamed; Habib, Ahmed Ali

    2012-01-01

    PURPOSE To compare the changes in the occlusal vertical dimension, activity of masseter muscles and biting force after insertion of immediate denture constructed with conventional, tooth-supported and Implant-supported immediate mandibular complete denture. MATERIALS AND METHODS Patients were selected and treatment was carried out with all the three different concepts i.e, immediate denture constructed with conventional (Group A), tooth-supported (Group B) and Implant-supported (Group C) immediate mandibular complete dentures. Parameters of evaluation and comparison were occlusal vertical dimension measured by radiograph (at three different time intervals), Masseter muscle electromyographic (EMG) measurement by EMG analysis (at three different positions of jaws) and bite force measured by force transducer (at two different time intervals). The obtained data were statistically analyzed by using ANOVA-F test at 5% level of significance. If the F test was significant, Least Significant Difference test was performed to test further significant differences between variables. RESULTS Comparison between mean differences in occlusal vertical dimension for tested groups showed that it was only statistically significant at 1 year after immediate dentures insertion. Comparison between mean differences in wavelet packet coefficients of the electromyographic signals of masseter muscles for tested groups was not significant at rest position, but significant at initial contact position and maximum voluntary clench position. Comparison between mean differences in maximum biting force for tested groups was not statistically significant at 5% level of significance. CONCLUSION Immediate complete overdentures whether tooth or implant supported prosthesis is recommended than totally mucosal supported prosthesis. PMID:22737309

  5. Effect of retention design of artificial teeth and implant-supported titanium CAD-CAM structures on fracture resistance

    PubMed Central

    Ladetzki, Kristin; Mateos-Palacios, Rocío; Pascual-Moscardó, Agustín

    2016-01-01

    Background For implant-supported hybrid prostheses, high mastication forces and reduced acrylic resin thickness over a metal substructure often cause failures arising from tooth or resin fractures. To assay fracture resistance of artificial teeth and resin in implant-supported hybrid prostheses in relation to the titanium structure and retention design supporting teeth. Material and Methods 40 specimens bearing incisors were divided into four groups according to the titanium structure supporting the teeth and the type of load force applied: Group I (Control; n=10): Application of static loading to ten incisors set over a metal structure with internal retention. Group II (Control; n=10): Application of static loading to ten incisors set over a metal structure with external retention. The remaining study specimens (n=20) were subjected to 120,000 masticatory and thermal cycles in a chewing simulator. Afterwards, static loading was applied until the point of fracture using an Instron machine. Group III (Study; n=10): Application of dynamic and static loading to ten incisors set over a metal structure with internal retention. Group IV (Study; n=10): Application of dynamic and static loading to ten incisors set over a metal structure with external retention. Data obtained for the four groups was analyzed and compared, determining the type of fracture (cohesive or adhesive) using a reflected light microscope. Results Statistical analysis confirmed that there were significant differences in fracture resistance between the four groups. External retention was found to have more fracture resistance than the internal retention. Conclusions Hybrid prostheses with titanium substructures and external retention obtained significantly better results than samples with internal retention. Key words:Chewing simulator, thermocycler, fatigue, implant-supported hybrid prosthesis, acrylic teeth, fracture, metal structure design. PMID:27034748

  6. Impact of Community-Based Residential Facilities for Mentally Retarded Adults on Surrounding Property Values Using Realtor Analysis Methods.

    ERIC Educational Resources Information Center

    Wiener, Dirk; And Others

    1982-01-01

    Analysis of a Comparable Market Analysis procedure used by realtors to determine the impact of group homes for the mentally retarded upon surrounding property values indicated no negative property value effects in six of eight instances. (Author/CL)

  7. Stress distribution in implant-supported prostheses using different connection systems and cantilever lengths: digital photoelasticity.

    PubMed

    Goiato, Marcelo Coelho; Shibayama, Ricardo; Gennari Filho, Humberto; de Medeiros, Rodrigo Antonio; Pesqueira, Aldiéris Alves; dos Santos, Daniela Micheline; de Araújo, Cleudmar Amaral

    2016-01-01

    Photoelastic analysis was used to evaluate the biomechanical behaviour of implant-supported, double-screwed crowns with different connection systems and cantilever lengths. Three models were made in PL-2 photoelastic resin and divided into six groups, on the basis of the implant connection system (external hexagon [EH] or Morse taper [MT]), type of abutment (Mini Pilar [Neodent, Curitiba, Paraná, Brazil] or "UCLA") and number of crowns in the cantilever (one or two). The implant-prosthesis unit was placed in a circular polariscope. Occlusal surfaces of the crowns were subjected to 100-N loads in the axial and oblique (45°) directions in a universal testing machine (EMIC). Generated stresses were recorded and analysed qualitatively in a graphics program (Adobe Photoshop). Under axial loading, all of the groups had similar numbers of fringes, which were increased when the crowns were subjected to oblique loading. The highest number of fringes was found during oblique loading in the EH + Mini Pilar group. In conclusion, although the type of implant connection system did not have a direct influence on the stress distribution for axial loading, the cantilever length did have a direct influence on stress distribution. Models with two crowns in the cantilever showed more stress, with a greater concentration of force on the cervical part of the implant. PMID:26783652

  8. Fabrication of an Implant-Supported Orbital Prosthesis with Bar-Magnetic Attachment: A Clinical Report.

    PubMed

    Aalaei, Shima; Abolhassani, Abolhassan; Nematollahi, Fatemeh; Beyabanaki, Elaheh; Mangoli, Amir Ali

    2015-12-01

    Implant-supported craniofacial prostheses are made to restore defective areas in the face and cranium. This clinical report describes a technique for fabrication of an orbital prosthesis with three adjacent implants in the left lateral orbital rim of a 60-year-old woman. Selection of appropriate attachment system (individual magnetic abutments versus bar-clip attachment) for implant-supported orbital prostheses depends upon the position of implants. Bar-magnetic attachment has been selected as the retention mechanism in the present case. PMID:27559354

  9. Fabrication of an Implant-Supported Orbital Prosthesis with Bar-Magnetic Attachment: A Clinical Report

    PubMed Central

    Aalaei, Shima; Abolhassani, Abolhassan; Nematollahi, Fatemeh; Beyabanaki, Elaheh; Mangoli, Amir Ali

    2015-01-01

    Implant-supported craniofacial prostheses are made to restore defective areas in the face and cranium. This clinical report describes a technique for fabrication of an orbital prosthesis with three adjacent implants in the left lateral orbital rim of a 60-year-old woman. Selection of appropriate attachment system (individual magnetic abutments versus bar-clip attachment) for implant-supported orbital prostheses depends upon the position of implants. Bar-magnetic attachment has been selected as the retention mechanism in the present case. PMID:27559354

  10. Implant-connected versus tooth-connected implant-supported partial dentures: 2-year clinical and radiographic comparative evaluation.

    PubMed

    Mostafa, Tamer Mohamed; El-Sheikh, Mohamed M; Abd El-Fattah, Fadel

    2015-01-01

    The purpose of this study was to clinically and radiographically compare implant-connected and tooth-connected implant-supported fixed-detachable mandibular partial dentures. Twenty partially edentulous patients (age range: 25 to 50 years) with mandibular Kennedy Class II configurations were equally divided into two groups receiving a three-unit, fixed-detachable, screw-retained partial denture. Group 1 comprised patients with unilateral missing mandibular molars and premolars. Two implants were placed at the mandibular first premolar and first molar areas. Group 2 comprised patients with missing mandibular molars and second premolars. An implant was placed at the mandibular first molar area, the first premolar was prepared, and a coping was cemented to the tooth with permanent cement. Each case was evaluated clinically and radiographically at baseline (partial denture insertion) and after 6, 12, and 24 months. Data were collected and statistically analyzed using repeated-measures one-way and two-way analysis of variance tests. There was no statistically significant difference between the two groups (P > .05). The implant-tooth-supported prosthesis provided an equally predictable treatment option compared to the totally implant-supported prosthesis in terms of implant survival and loss of marginal bone. PMID:25909533

  11. A systematic analysis of the influence of the surrounding media in the photothermal beam deflection signal

    NASA Astrophysics Data System (ADS)

    Gören, A.; Prior, P.; Macedo, F.

    2010-03-01

    The photothermal beam deflection (PDS) technique was tested for low thermal diffusivity materials. The effect of using different liquids as surrounding media was studied in a systematic way. The fundamental experimental parameters, like the pump beam power and the modulation frequency were also studied in order to find out the best combination that still allows us to get good signals. Due to the complexity of the optical alignment required, the usual mirage setup was adapted in order to allow the decoupling of the alignment of the cell containing the liquid and the sample holder. Simple, straightforward methods (like e.g. the phase method) were used for the thermal diffusivity determination of solids once the thermal diffusivity of the liquids used is always much lower than that of solids. The obtained values for the thermal diffusivity of test samples allow us to conclude that besides being possible to use any of the studied liquids as surrounding medium, ethanol is clearly the best choice, avoiding health problems related to CCl4, which is the standard choice for PDS and PDS spectroscopy experiments, and technical/physical problems related to water and acetone. Modulation frequencies around 8 Hz combined with a pump beam power below 15 mW were proved to be the ideal conditions for this kind of experiment. The very low pump beam power required is also an important issue when talking about non-destructive analysis.

  12. Rehabilitation with implant-supported overdentures in total edentulous patients: A review

    PubMed Central

    Segura-Andrés, Gustavo; Faus-López, Joan; Agustín-Panadero, Rubén

    2013-01-01

    Objectives: The main aim of this review article is to discuss implant-supported overdentures (ISOs) as treatment in edentulous patients. Besides, we will try to discuss among the different treatment options in such patients and to analyze their validity when ISOs are compared with other clinical modalities. At the same time, we will try to suggest clinical guidelines supported by current clinical studies. Material and methods: We performed a Medline search and review of pertinent articles on the mentioned subject from 1986 to 2011. As a searching strategy, we used the following words: implant-supported overdentures, attachment systems, Locator attachment, cantilever, fixed prosthesis. Results and conclusions: Implant-supported overdentures constitute an accurate and predictable treatment option and achieve a higher patients’ satisfaction. This type of treatment constitutes a cheaper treatment than fixed prostheses and in some patients, with loss of lip support or with an interoclusal space larger than 15 mm, the choice of implant-supported overdentures seems to prevent future aesthetic or phonetic problems. Key words:Overdentures, implant occlusion, implant rehabilitation, total edentulous rehabilitation, fixed prosthesis. PMID:24455093

  13. Prevalence of complications after the oral rehabilitation with implant-supported hybrid prostheses

    PubMed Central

    Almendros-Marqués, Nieves; Gay-Escoda, Cosme

    2012-01-01

    Objectives: Assess the main problems referred by the patients and observed by the professionals after the bucodental rehabilitation with an implant-supported hybrid prothesis. Patient and Methods: A retrospective study was carried out in which there were 43 patients included who were visited in the Department of Oral Surgery and Orofacial Implantology of University of Barcelona Dental School for one year. An oral rehabilitation with an implant-supported hybrid prosthesis was made to those patients. The following variables were registered: age, gender, number of inserted implants, type of implant and principal problems produced by the hybrid prosthesis. Results: The rehabilitation with an implant supported hybrid prosthesis was only performed in 43 of 116 cases treated in one year (January, 2006 to January, 2007). They were 26 men and 17 women of ages between 37 and 74 years, being the rate age of 56,5 years. The main complication recorded was the mucositis, associated frequently with a difficulty to carry a correct oral hygiene and to an overextention of the tail of resin of the prosthesis. Other observed problems were the peri-implantitis, the break of the acrylic teeth and the loss of some of the prosthetic screws. Conclusions: The most frequent complication after the laying of an implant supported hybrid prosthesis was the mucositis, associated mainly with a prosthetic tail too long and to the consequent difficulty of carrying a correct oral hygiene. In spite of the high prevalence of observed complications, most of them were mild and resolved on subsequent visits. Key words: Implant supported hybrid prosthesis, complications and prosthetic fails. PMID:21743427

  14. Retention of Implant Supported Metal Crowns Cemented with Different Luting Agents: A Comparative Invitro Study

    PubMed Central

    Singh, Kavipal; Kaur, Simrat; Arora, Aman

    2016-01-01

    Introduction To overcome limitations of screw-retained prostheses, cement-retained prostheses have become the restoration of choice now a days. Selection of the cement hence becomes very critical to maintain retrievability of the prostheses. Aim The purpose of this study was to assess and compare the retention of base metal crowns cemented to implant abutments with five different luting cements. Materials and Methods Ten implant analogs were secured in five epoxy resin casts perpendicular to the plane of cast in right first molar and left first molar region and implant abutments were screwed. Total of 100 metal copings were fabricated and cemented. The cements used were zinc phosphate, resin modified glass ionomer cement, resin cement, non-eugenol acrylic based temporary implant cement & non-eugenol temporary resin cement implant cement. Samples were subjected to a pull-out test using an Instron universal testing machine at a crosshead speed of 0.5mm/min. The load required to de-cement each coping was recorded and mean values for each group calculated and put to statistical analysis. Results The results showed that resin cement has the highest retention value 581.075N followed by zinc phosphate luting cement 529.48N, resin modified glass ionomer cement 338.095 N, non-eugenol acrylic based temporary implant cement 249.045 N and non-eugenol temporary resin implant cement 140.49N. Conclusion Within the limitations of study, it was concluded that non-eugenol acrylic based temporary implant cement and non-eugenol temporary resin implant cement allow for easy retrievability of the prosthesis in case of any failure in future. These are suitable for cement retained implant restorations. The results provide a possible preliminary ranking of luting agents based on their ability to retain an implant-supported prosthesis and facilitate easy retrieval. PMID:27190954

  15. Influence of finish line in the distribution of stress trough an all ceramic implant-supported crown.

    PubMed Central

    SANNINO, G.; GLORIA, F.; OTTRIA, L.; BARLATTANI, A.

    2010-01-01

    SUMMARY Porpose. The aim of this study was to evaluate, by finite element analysis (FEA), the influence of finish line on stress distribution and resistance to the loads of a ZrO2 crown and porcelain in implant-supported. Material and methods. The object of this analysis consisted of a fxture, an abutment, a passing screw, a layer of cement, a framework crown, a feldspatic porcelain veneering. The abutment’s marginal design was used in 3 different types of preparation: feather edge, slight chamfer and 50°, each of them was of 1 mm depth over the entire circumference. The ZrO2Y-TZP coping was 0.6 mm thick. Two material matching for the abutment and the framework was used for the simulations: ZrO2 framework and ZrO2 abutment, ZrO2 framework and T abutment. A 600 N axial force distributed over the entire surface of the crown was applied. The numerical simulations with finite elements were used to verify the different distribution of equivalent von Mises stress for three different geometries of abutment and framework. Results Slight chamfer on the matching ZrO2 - ZrO2 is the geometry with minimum equivalent stress of von Mises. Even for T abutment and ZrO2 framework slight chamfer is the best configuration to minimize the localized stress. Geometry that has the highest average stress is one with abutment at 50°, we see a downward trend for all three configurations using only zirconium for both components. Conclusions Finite element analysis. performed for the manifacturing of implant-supported crown, gives exact geometric guide lines about the choice of chamfer preparation, while the analysis of other marginal geometries suggests a possible improved behavior of the mating between ZrO2 abutment and ZrO2 coping. for three different geometries of the abutment and the coping. PMID:23285359

  16. Implant Supported Mandibular Overdenture: A Viable Treatment Option for Edentulous Mandible

    PubMed Central

    Lambade, Pravin; Gundawar, Sham

    2014-01-01

    The prosthetic management of the edentulous patient has long been a major challenge. Complete maxillary and mandibular dentures have been the traditional standard of care. However, most of the patients report problems adapting to their mandibular denture due to a lack of comfort, retention, stability and inability to masticate. Implant-supported overdentures have been a common treatment for edentulous patients for the past 20 years and predictably achieve good clinical results. Implant supported overdentures offer many practical advantages over conventional complete dentures and removable partial dentures. These include decreased bone resorption, reduced prosthesis movement, better esthetics, improved tooth position, better occlusion, increased occlusal function and maintenance of the occlusal vertical dimension. This article presents a design and fabrication technique of the implant-retained overdenture that uses four freestanding mandibular implants. PMID:24995252

  17. Maxillary cement retained implant supported monolithic zirconia prosthesis in a full mouth rehabilitation: a clinical report

    PubMed Central

    Liu, Perng-Ru; Aponte-Wesson, Ruth; O'Neal, Sandra J

    2013-01-01

    This clinical report presents the reconstruction of a maxillary arch with a cement retained implant supported fixed prosthesis using a monolithic zirconia generated by CAD/CAM system on eight osseointegrated implants. The prosthesis was copy milled from an interim prosthesis minimizing occlusal adjustments on the definitive prosthesis at the time of delivery. Monolithic zirconia provides high esthetics and reduces the number of metal alloys used in the oral cavity. PMID:23755349

  18. Implant-supported hybrid prosthesis: Conventional treatment method for borderline cases

    PubMed Central

    Egilmez, Ferhan; Ergun, Gulfem; Cekic-Nagas, Isil; Bozkaya, Suleyman

    2015-01-01

    An implant-supported hybrid prosthesis is an acrylic resin complete fixed dental prosthesis and supported by implants might be a solution in extreme cases that the need of the restoration for esthetics, function, lip support, and speech. This clinical report aims to present the esthetic and functional prosthetic rehabilitation of three borderline cases with implant-supported hybrid prostheses. Patient 1 (62-year-old man) and Patient 2 (61-year-old man) presented a chief complaint of a compromised esthetic. After clinical evaluations, in Patient 1, 8 implants in the maxilla and 7 implants in mandibula were observed. Patient 2 had 7 implants in the maxilla and 7 implants in mandibula, which were previously placed. The intra-arch dimension of both patients was excessive and an insufficient peri-oral soft tissue support was observed. Patient 3 was a 61-year-old man had 2 implants with a history of previously implanted graft infection and implant loss on his maxillary posterior jaw. An excessive intra-arch dimension was observed in clinical examination. In addition, massive bone defect and insufficient soft tissue support were examined. In all patients, implant-supported hybrid prostheses were successfully performed. The clinical and radiologic findings were satisfactory. After 3 years of follow-up, no functional, phonetic, or esthetic problems with the restorations were noted. These case reports suggest that implant-supported hybrid prostheses can be a reliable alternative treatment procedure when a porcelain-fused metal fixed restoration does not satisfy a patient's requirements for esthetics, phonetics, oral hygiene, and oral comfort. PMID:26430378

  19. Mandibular implant-supported fixed dental prosthesis with a modified design: a clinical report.

    PubMed

    Tourah, Anita; Moshaverinia, Alireza; Chee, Winston W

    2014-02-01

    This clinical report describes the rehabilitation of a patient with a mandibular implant-supported fixed dental prosthesis. Because of the limited restorative space available in the posterior mandible and in considering the higher wear rate of acrylic resin in comparison with titanium when it opposes metal ceramic restorations, the treatment used a milled titanium bar with acrylic resin denture teeth, which replaced the anterior teeth with milled titanium for the posterior occluding surfaces. PMID:24262946

  20. Prosthetic misfit of implant-supported prosthesis obtained by an alternative section method

    PubMed Central

    Falcão-Filho, Hilmo Barreto Leite; de Aguiar, Fábio Afrânio; Rodrigues, Renata Cristina Silveira; de Mattos, Maria da Gloria Chiarello; Ribeiro, Ricardo Faria

    2012-01-01

    PURPOSE Adequate passive-fitting of one-piece cast 3-element implant-supported frameworks is hard to achieve. This short communication aims to present an alternative method for section of one-piece cast frameworks and for casting implant-supported frameworks. MATERIALS AND METHODS Three-unit implant-supported nickel-chromium (Ni-Cr) frameworks were tested for vertical misfit (n = 6). The frameworks were cast as one-piece (Group A) and later transversally sectioned through a diagonal axis (Group B) and compared to frameworks that were cast diagonally separated (Group C). All separated frameworks were laser welded. Only one side of the frameworks was screwed. RESULTS The results on the tightened side were significantly lower in Group C (6.43 ± 3.24 µm) when compared to Groups A (16.50 ± 7.55 µm) and B (16.27 ± 1.71 µm) (P<.05). On the opposite side, the diagonal section of the one-piece castings for laser welding showed significant improvement in the levels of misfit of the frameworks (Group A, 58.66±14.30 µm; Group B, 39.48±12.03 µm; Group C, 23.13±8.24 µm) (P<.05). CONCLUSION Casting diagonally sectioned frameworks lowers the misfit levels. Lower misfit levels for the frameworks can be achieved by diagonally sectioning one-piece frameworks. PMID:22737313

  1. Implant-supported overdenture with prefabricated bar attachment system in mandibular edentulous patient

    PubMed Central

    Ha, Seung-Ryong; Song, Seung-Il; Hong, Seong-Tae; Kim, Gy-Young

    2012-01-01

    Implant-supported overdenture is a reliable treatment option for the patients with edentulous mandible when they have difficulty in using complete dentures. Several options have been used for implant-supported overdenture attachments. Among these, bar attachment system has greater retention and better maintainability than others. SFI-Bar® is prefabricated and can be adjustable at chairside. Therefore, laboratory procedures such as soldering and welding are unnecessary, which leads to fewer errors and lower costs. A 67-year-old female patient presented, complaining of mobility of lower anterior teeth with old denture. She had been wearing complete denture in the maxilla and removable partial denture in the mandible with severe bone loss. After extracting the teeth, two implants were placed in front of mental foramen, and SFI-Bar® was connected. A tube bar was seated to two adapters through large ball joints and fixation screws, connecting each implant. The length of the tube bar was adjusted according to inter-implant distance. Then, a female part was attached to the bar beneath the new denture. This clinical report describes two-implant-supported overdenture using the SFI-Bar® system in a mandibular edentulous patient. PMID:23236580

  2. Integrated passenger terminal capacity analysis under the capacity constraints of surrounding road network

    NASA Astrophysics Data System (ADS)

    Zhou, Xuemei; Huang, Huang; Jia, Xinchang; Jiang, Nan

    2014-11-01

    Forecasting the demand of an integrated passenger terminal under the capacity constraints of its surrounding roads has always been a challenging problem for urban transportation terminals planning and construction in China. A bi-level model is proposed to forecast the passenger demand of an integrated terminal, whose throughput is restricted by the capacity of its surrounding road network. The upper level model maximizes the passenger flow of a terminal considering the capacity constraints of its surrounding road network. The User Equilibrium (UE) model is adopted as lower level model for traffic assignment. The adaptive genetic algorithm (AGA) is applied to solve this bi-level problem. The West-Lanzhou integrated passenger terminal in the Lanzhou city of China is used to test the feasibility and effectiveness of the proposed model. Test results show that, to reduce traffic congestion at the terminal, priority should be given to transportation mode with higher performance.

  3. Reliability and fatigue failure modes of implant-supported aluminum-oxide fixed dental prostheses

    PubMed Central

    Stappert, Christian F. J.; Baldassarri, Marta; Zhang, Yu; Hänssler, Felix; Rekow, Elizabeth D.; Thompson, Van P.

    2012-01-01

    Objectives To investigate failure modes and reliability of implant-supported aluminum-oxide three-unit fixed-dental-prostheses (FDPs) using two different veneering porcelains. Material and methods Thirty-six aluminum-oxide FDP-frameworks were CAD/CAM fabricated and either hand-veneered(n=18) or over-pressed(n=18). All FDPs were adhesively luted to custom-made zirconium-oxide-abutments attached to dental implant fixtures (RP-4×13mm). Specimens were stored in water prior to mechanical testing. A Step-Stress-Accelerated-Life-Test (SSALT) with three load/cycles varying profiles was developed based on initial single-load-to-failure testing. Failure was defined by veneer chipping or chipping in combination with framework fracture. SSALT was performed on each FDP inclined 30° with respect to the applied load direction. For all specimens, failure modes were analyzed using polarized-reflected-light-microscopy and scanning-electron-microscopy (SEM). Reliability was computed using Weibull analysis software (Reliasoft). Results The dominant failure mode for the over-pressed FDPs was buccal chipping of the porcelain in the loading area of the pontic, while hand-veneered specimens failed mainly by combined failure modes in the veneering porcelain, framework and abutments. Chipping of the porcelain occurred earlier in the over-pressed specimens (350 N/85k, load/cycles) than in the hand-veneered (600 N/110k)(profile I). Given a mission at 300 N load and 100k or 200 K cycles the computed Weibull reliability (2-sided at 90.0 % confidence bounds) was 0.99(1/0.98) and 0.99(1/0.98) for hand-veneered FDPs, and 0.45(0.76/0.10) and 0.05(0.63/0) for over-pressed FDPs, respectively. Conclusions In the range of average clinical loads (300–700 N), hand-veneered aluminum-oxide FDPs showed significantly less failure by chipping of the veneer than the over-pressed. Hand-veneered FDPs under fatigue loading failed at loads ≥ 600N. PMID:22093019

  4. Road condition analysis using NIR illumination and compensating for surrounding light

    NASA Astrophysics Data System (ADS)

    Casselgren, Johan; Rosendahl, Sara; Sjödahl, Mikael; Jonsson, Patrik

    2016-02-01

    An investigation of a NIR camera system for road surface classification has been conducted for several road conditions. The surfaces were illuminated with three wavelengths, 980 nm, 1310 nm and 1550 nm and a halogen lamp, to simulate a real environment application with surrounding light. A measuring scheme to deal with surrounding light has been implemented enabling road condition classification from NIR images in a real environment. The retrieved camera images have been analyzed and an RGB representation of the different surfaces has been created to classify the different road conditions. The investigation shows that it is possible to distinguish between dry, moist, wet, frosty, icy and snowy road surfaces using a NIR camera system in a disturbed environment.

  5. Surrounding Greenness and Exposure to Air Pollution During Pregnancy: An Analysis of Personal Monitoring Data

    PubMed Central

    de Nazelle, Audrey; Triguero-Mas, Margarita; Schembari, Anna; Cirach, Marta; Amoly, Elmira; Figueras, Francesc; Basagaña, Xavier; Ostro, Bart; Nieuwenhuijsen, Mark

    2012-01-01

    Background: Green spaces are reported to improve health status, including beneficial effects on pregnancy outcomes. Despite the suggestions of air pollution–related health benefits of green spaces, there is no available evidence on the impact of greenness on personal exposure to air pollution. Objectives: We investigated the association between surrounding greenness and personal exposure to air pollution among pregnant women and to explore the potential mechanisms, if any, behind this association. Methods: In total, 65 rounds of sampling were carried out for 54 pregnant women who resided in Barcelona during 2008–2009. Each round consisted of a 2-day measurement of particulate matter with aerodynamic diameter ≤ 2.5 μm (PM2.5) and a 1-week measurement of nitric oxides collected simultaneously at both the personal and microenvironmental levels. The study participants were also asked to fill out a time–microenvironment–activity diary during the sampling period. We used satellite retrievals to determine the surrounding greenness as the average of Normalized Difference Vegetation Index (NDVI) in a buffer of 100 m around each maternal residential address. We estimated the impact of surrounding greenness on personal exposure levels, home-outdoor and home-indoor pollutant levels, and maternal time-activity. Results: Higher residential surrounding greenness was associated with lower personal, home-indoor, and home-outdoor PM2.5 levels, and more time spent at home-outdoor. Conclusions: We found lower levels of personal exposure to air pollution among pregnant women residing in greener areas. This finding may be partly explained by lower home-indoor pollutant levels and more time spent in less polluted home-outdoor environment by pregnant women in greener areas. PMID:22647671

  6. Full Mouth Oral Rehabilitation by Maxillary Implant Supported Hybrid Denture Employing a Fiber Reinforced Material Instead of Conventional PMMA

    PubMed Central

    Qamheya, Ala Hassan A.; Yeniyol, Sinem; Arısan, Volkan

    2015-01-01

    Many people have life-long problems with their dentures, such as difficulties with speaking and eating, loose denture, and sore mouth syndrome. The evolution of dental implant supported prosthesis gives these patients normal healthy life for their functional and esthetic advantages. This case report presents the fabrication of maxillary implant supported hybrid prosthesis by using Nanofilled Composite (NFC) material in teeth construction to rehabilitate a complete denture wearer patient. PMID:26557392

  7. Gingival Embrasure Fill In Fixed Implant-Supported Prosthetics: A Review.

    PubMed

    Flanagan, Dennis

    2015-12-01

    After provisional or definitive cementation of fixed implant-supported prostheses, spontaneous gingival proliferation may occur to fill the cervical embrasure areas of the prosthesis. Adequate oral hygiene, osseous spacing between the supporting implants and attached or immovable soft tissue may be the conditions that allow this phenomenon. This proliferation embrasure fill eliminates interproximal gingival voids, that is, black triangles, and makes the outcome more esthetically acceptable. Since interproximal prosthetic deign and implant positioning may be the primary factors for the fill, the gingival fill may be, in fact, an epulis. PMID:25545968

  8. Zygoma Implant-Supported Prosthetic Rehabilitation of a Patient After Bilateral Maxillectomy.

    PubMed

    Celakil, Tamer; Ayvalioglu, Demet Cagil; Sancakli, Erkan; Atalay, Belir; Doganay, Ozge; Kayhan, Kivanc Bektas

    2015-10-01

    Maxillectomy defects may vary from localized to extensive soft and hard tissue loss. In addition to physical and psychologic damages, functional and aesthetic aspects must be restored. This clinical report describes the rehabilitation of a patient with a zygoma implant-supported obturator prosthesis caused by a subtotal bilateral maxillectomy due to a squamous oral cell carcinoma. Prosthetic rehabilitation of this patient was performed after zygoma implant surgery. A maxillary obturator prosthesis supported by 2 osseointegrated zygoma implants was fabricated. Despite limited mouth opening and anatomic deficiencies, the patient's aesthetic and functional demands were fulfilled. PMID:26468845

  9. Digital process for an implant-supported fixed dental prosthesis: A clinical report.

    PubMed

    Brandt, Jan; Lauer, Hans-Christoph; Peter, Thorsten; Brandt, Silvia

    2015-10-01

    A digital process is presented for an implant-supported single-tooth and a 3-unit fixed dental prosthesis (FDP) with customized abutments and monolithic prosthetic zirconia restorations. The digital impression on the implant level was made with a TRIOS intraoral scanner (3Shape). This process included the fabrication of an implant cast with the fused deposition modeling technique and a 3-dimensional printing process with integrated implant analogs. The process enabled the FDPs to be designed with CAD/CAM on the cast before patient contact. Designing a printed implant cast expands the use of the digital workflow in the dental field. PMID:26187099

  10. Telescopic Overdenture and Implant Supported Fixed Partial Denture: A Pragmatic Treatment Approach

    PubMed Central

    Dede, Doğu Ömür; Cenk Durmuşlar, M.; Şahın, Onur; Köroğlu, Ayşegül; İşısağ, Özer

    2015-01-01

    This case report presents a patient who had been rehabilitated with a telescopic overdenture and implant supported fixed partial denture (ISFPD). The treatment process was as follows: (1) fabricating telescopic crowns and overdenture prosthesis for the lower jaw and a temporary complete denture for the upper jaw, (2) using the temporary denture as diagnostic and surgical guide to optimize dental implant placement, and (3) fabricating ISFPD for the upper jaw. Using the patient's existing or temporary denture not only serves as an alternative surgical guide to calibrate the dental implant locations but also helps to finish the restoration at desired dimension, size, and anatomic form. PMID:26106491

  11. Numerical Simulation Analysis of Deformation Effect of The Upper Mantle Flow to Ordos and Its Surroundings

    NASA Astrophysics Data System (ADS)

    Yun, S.; Ping, L. C.; Qi, D.

    2014-12-01

    Ordos block is a typical representative of cratonic lithosphere in North China. It is stable in the block ,but around the block there are a series of faulted basins and folded mountains, the new tectonic movement around the block is intense. Some scholars propose that the upper mantle flow is an important factor to the extension activity of the fault zone around the block. But it has never been discussed in detail that how the upper mantle flow affects the movement and deformation around Ordos block? A 3D viscoelastic modeling is realized for studying the deformation effect of the upper mantle flow to Ordos and its surroundings, based on the comprehensive geological and geophysical data ,such as 3d rheological structure, the active blocks of China, thermal structure, shear wave splitting, et al. The modeling results indicate that in the vertical direction, compared with the local uplift and depression caused by the compression among the plates, the uplifting of Ordos block as a whole is mainly effected by mantle upwelling. In general the upper mantle surrounding of Ordos block is upwelling, Linfen basin goes up more faster. In the horizontal direction, The general flow direction of upper mantle in the study area is NE, basically the same as Qingzang block movement direction. But there is a bifurcation flow along the southwestern margin of Liupanshan. Generally speaking, the regional deformation is drive mainly by the movement of Qingzang block and adjacent blocks pushing into each other,the deformation effect of the upper mantle flow to Ordos and its surroundings is a superposition and partial adjustment.

  12. Metagenomic analysis of bacterial and archaeal assemblages in the soil-mousse surrounding a geothermal spring.

    PubMed

    Bhatia, Sonu; Batra, Navneet; Pathak, Ashish; Joshi, Amit; Souza, Leila; Almeida, Paulo; Chauhan, Ashvini

    2015-09-01

    The soil-mousse surrounding a geothermal spring was analyzed for bacterial and archaeal diversity using 16S rRNA gene amplicon metagenomic sequencing which revealed the presence of 18 bacterial phyla distributed across 109 families and 219 genera. Firmicutes, Actinobacteria, and the Deinococcus-Thermus group were the predominant bacterial assemblages with Crenarchaeota and Thaumarchaeota as the main archaeal assemblages in this largely understudied geothermal habitat. Several metagenome sequences remained taxonomically unassigned suggesting the presence of a repertoire of hitherto undescribed microbes in this geothermal soil-mousse econiche. PMID:26484255

  13. Metagenomic analysis of bacterial and archaeal assemblages in the soil-mousse surrounding a geothermal spring

    PubMed Central

    Bhatia, Sonu; Batra, Navneet; Pathak, Ashish; Joshi, Amit; Souza, Leila; Almeida, Paulo; Chauhan, Ashvini

    2015-01-01

    The soil-mousse surrounding a geothermal spring was analyzed for bacterial and archaeal diversity using 16S rRNA gene amplicon metagenomic sequencing which revealed the presence of 18 bacterial phyla distributed across 109 families and 219 genera. Firmicutes, Actinobacteria, and the Deinococcus-Thermus group were the predominant bacterial assemblages with Crenarchaeota and Thaumarchaeota as the main archaeal assemblages in this largely understudied geothermal habitat. Several metagenome sequences remained taxonomically unassigned suggesting the presence of a repertoire of hitherto undescribed microbes in this geothermal soil-mousse econiche. PMID:26484255

  14. Oral health-related quality of life of implant-supported overdentures versus conventional complete prostheses: Retrospective study of a cohort of edentulous patients

    PubMed Central

    Selva-Otaolaurruchi, Eduardo J.; Montero, Javier; Sola-Ruiz, Fernanda

    2015-01-01

    Background This work aims to confirm if implant-supported overdentures are a good treatment option for edentulous patients and offer an improvement in quality of life compared with traditional complete prostheses (dentures). Material and Methods This retrospective clinical descriptive study included three evaluation groups: validation group (n=57); control group of patients with complete removeable prostheses (n=56); study group of patients with implant-supported overdentures retained with the Locator® system (n=80). The study also validated the Oral Health Impact Profile-20 questionnaire. Individual protocols were created that included socio-demographic data, the Oral Health Impact Profile-20 (OHIP-20) questionnaire and Oral Satisfaction Scale (OSS). Descriptive and bivariate statistical analysis was carried out applying χ², Pearson, Kruskal-Wallis, and Student t tests, transferring data into SPSS-Windows® software from a Microsoft® Excel spreadsheet. Results The OHIP-20 proved to be a valid instrument and provided reliable assessment of health-related quality of life among both the Spanish general population and edentulous patients. The control and study groups proved comparable, showing socio-demographic homogeneity. For patients with overdentures retained by means of the Locator® system, these restorations had significantly lower impact on quality of life (19 vs 33), both generally and for each individual questionnaire item, and much higher satisfaction with the state of their oral cavities (8.3 vs 5.3) than patients wearing dentures; both sets of data showed a direct linear relationship, so that as the level of impact on quality of life increased, perceived oral satisfaction worsened. Conclusions Patients rehabilitated with implant supported overdentures retained by the Locator® system, presented significantly lower levels of impact on their quality of life and significantly higher oral satisfaction than patients with conventional complete prostheses

  15. The effect of flexible acrylic resin on masticatory muscle activity in implant-supported mandibular overdentures: a controlled clinical trial

    PubMed Central

    Ibraheem, Eman Mostafa Ahmed; Nassani, Mohammad Zakaria

    2016-01-01

    Background It is not yet clear from the current literature to what extent masticatory muscle activity is affected by the use of flexible acrylic resin in the construction of implant-supported mandibular overdentures. Objective To compare masticatory muscle activity between patients who were provided with implant-supported mandibular overdentures constructed from flexible acrylic resin and those who were provided with implant-supported mandibular overdentures constructed from heat-cured conventional acrylic resin. Methods In this clinical trial, 12 completely edentulous patients were selected and randomly allocated into two equal treatment groups. Each patient in Group 1 received two implants to support a mandibular overdenture made of conventional acrylic resin. In Group 2, the patients received two implants to support mandibular overdentures constructed from “Versacryl” flexible acrylic resin. The maxillary edentulous arch for patients in both groups was restored by conventional complete dentures. For all patients, masseter and temporalis muscle activity was evaluated using surface electromyography (sEMG). Results The results showed a significant decrease in masticatory muscle activity among patients with implant-supported mandibular overdentures constructed from flexible acrylic resin. Conclusion The use of “Versacryl” flexible acrylic resin in the construction of implant-supported mandibular overdentures resulted in decreased masticatory muscle activity. PMID:26955445

  16. Thermal analysis of the surrounding anatomy during 3-D MRI-guided transurethral ultrasound prostate therapy

    NASA Astrophysics Data System (ADS)

    Burtnyk, Mathieu; Chopra, Rajiv; Bronskill, Michael

    2010-03-01

    Previous numerical simulations have shown that MRI-guided transurethral ultrasound therapy can generate highly accurate volumes of thermal coagulation conforming to 3-D human prostate geometries. The goal of this work is to simulate, quantify and evaluate the thermal impact of these treatments on the rectum, pelvic bone, neurovascular bundles (NVB) and urinary sphincters. This study used twenty 3-D anatomical models of prostate cancer patients and detailed bio-acoustic simulations incorporating an active feedback algorithm which controlled a rotating, planar ultrasound transducer (17-4×3 mm elements, 4.7/9.7 MHz, 10 Wac/cm2). Heating of the adjacent surrounding anatomy was evaluated using thermal tolerances reported in the literature. Heating of the rectum poses the most important safety concern and is influenced largely by the water temperature flowing through an endorectal cooling device; temperatures of 7-37° C are required to limit potential damage to less than 10 mm3 on the outer 1 mm layer of rectum. Significant heating of the pelvic bone was predicted in 30% of the patient models with an ultrasound frequency of 4.7 MHz; setting the frequency to 9.7 MHz when the bone is less than 10 mm away from the prostate reduced heating in all cases below the threshold for irreversible damage. Heating of the NVB was significant in 75% of the patient models in the absence of treatment planning; this proportion was reduced to 5% by using treatment margins of up to 4 mm. To avoid damaging the urinary sphincters, margins from the transducer of 2-4 mm should be used, depending on the transurethral cooling temperature. Simulations show that MRI-guided transurethral therapy can treat the entire prostate accurately. Strategies have been developed which, along with careful treatment planning, can be used to avoid causing thermal injury to the rectum, pelvic bone, NVB and urinary sphincters.

  17. Prosthetic Management of an Extensive Maxillary Alveolar Defect with an Implant-Supported Restoration

    PubMed Central

    Saadat, Fariborz; Mosharraf, Ramin

    2013-01-01

    Despite the recent developments in peri-implant surgical regenerative procedures, re-establishing the hard and soft tissue contour is still a challenge in cases with severe ridge deficiency. It becomes more difficult when incorrectly placed implants cause screw connections to come out onto the labial surfaces of the teeth. A two-part maxillary implant supported fixed restoration was constructed. The first part was consisted of a screw retained sub-structure that replaced gingival portions of the deficient maxilla and the second part was a cement retained super-structure that reconstructed the anatomical crowns of the lost teeth. In this way awkwardly placed implants did not interfere with the desired esthetic result. Another great advantage was that the alterations or repairs on cemented crowns can easily be carried out without compromising the entire construction. PMID:25512753

  18. Replacement of mandibular central incisors with implant-supported crowns: a case report.

    PubMed

    Bäumer, Daniel; Zuhr, Otto; Hürzeler, Markus

    2016-01-01

    Anterior teeth are often affected by accidental dental trauma and may eventually be lost. When the neighboring teeth are unharmed, implant-supported crowns are often the preferred treatment choice. When not only the teeth but also the supporting hard and soft tissue has been lost, surgical reconstruction may be needed. However, in combined horizontal and vertical class III defects, the available augmentation techniques are often not predictable. In this case report, two neighboring mandibular central incisors were replaced by two implants after soft and hard tissue augmentation with the cortical bone plate method. The interdental soft tissue was reconstructed with remarkable success, making this an example of what can be achieved in cases such as this. PMID:27092347

  19. Flexural strengths of implant-supported zirconia based bridges in posterior regions

    PubMed Central

    Rismanchian, Mansour; Nourbakhshian, Farzaneh; Davoudi, Amin

    2014-01-01

    PURPOSE Impact forces in implant supported FDP (fixed dental prosthesis) are higher than that of tooth supported FDPs and the compositions used in frameworks also has a paramount role for biomechanical reasons. The aim of this study was to evaluate the flexural strength of two different zirconia frameworks. MATERIALS AND METHODS Two implant abutments with 3.8 mm and 4.5 mm platform were used as premolar and molar. They were mounted vertically in an acrylic resin block. A model with steel retainers and removable abutments was fabricated by milling machine; and 10 FDP frameworks were fabricated for each Biodenta and Cercon systems. All samples were thermo-cycled for 2000 times in 5-55℃ temperature and embedded in 37℃ artificial saliva for one week. The flexural test was done by a rod with 2 mm ending diameter which was applied to the multi-electromechanical machine. The force was inserted until observing fracture. The collected data were analyzed with SPSS software ver.15, using Weibull modulus and independent t-test with the level of significance at α=.05. RESULTS The mean load bearing capacity values were higher in Biodenta but with no significant differences (P>.05). The Biodenta frameworks showed higher load bearing capacity (F0=1700) than Cercon frameworks (F0=1520) but the reliability (m) was higher in Cercon (m=7.5). CONCLUSION There was no significant difference between flexural strengths of both zirconia based framework systems; and both Biodenta and Cercon systems are capable to withstand biting force (even parafunctions) in posterior implant-supported bridges with no significant differences. PMID:25352956

  20. A structured analysis of uncertainty surrounding modeled impacts of groundwater-extraction rules

    NASA Astrophysics Data System (ADS)

    Guillaume, Joseph H. A.; Qureshi, M. Ejaz; Jakeman, Anthony J.

    2012-08-01

    Integrating economic and groundwater models for groundwater-management can help improve understanding of trade-offs involved between conflicting socioeconomic and biophysical objectives. However, there is significant uncertainty in most strategic decision-making situations, including in the models constructed to represent them. If not addressed, this uncertainty may be used to challenge the legitimacy of the models and decisions made using them. In this context, a preliminary uncertainty analysis was conducted of a dynamic coupled economic-groundwater model aimed at assessing groundwater extraction rules. The analysis demonstrates how a variety of uncertainties in such a model can be addressed. A number of methods are used including propagation of scenarios and bounds on parameters, multiple models, block bootstrap time-series sampling and robust linear regression for model calibration. These methods are described within the context of a theoretical uncertainty management framework, using a set of fundamental uncertainty management tasks and an uncertainty typology.

  1. RELATIONSHIP OF MAMMOGRAPHIC DENSITY AND GENE EXPRESSION: ANALYSIS OF NORMAL BREAST TISSUE SURROUNDING BREAST CANCER

    PubMed Central

    Sandhu, Rupninder; Williams, Tyisha; Midkiff, Bentley R.; Lissowska, Jolanta; Wesolowska, Ewa; Boyd, Norman F.; Johnson, Nicole B.; Figueroa, Jonine D.; Sherman, Mark E.; Troester, Melissa A.

    2014-01-01

    Purpose Previous studies of breast tissue gene expression have demonstrated that the extratumoral microenvironment has substantial variability across individuals, some of which can be attributed to epidemiologic factors. To evaluate how mammographic density (MD) and breast tissue composition relate to extratumoral microenvironment gene expression, we used data on 121 breast cancer patients from the population-based Polish Women's Breast Cancer Study. Design Breast cancer cases were classified based on a previously reported, biologically-defined extratumoral gene expression signature with two subtypes: an Active subtype, which is associated with high expression of genes related to fibrosis and wound response, and an Inactive subtype, which has high expression of cellular adhesion genes. MD of the contralateral breast was assessed using pre-treatment mammograms and a quantitative, reliable computer-assisted thresholding method. Breast tissue composition was evaluated based on digital image analysis of tissue sections. Results The Inactive extratumoral subtype was associated with significantly higher percentage mammographic density (PD) and dense area (DA) in univariate analysis (PD: p=0.001; DA: p=0.049) and in multivariable analyses adjusted for age and body mass index (PD: p=0.004; DA: p=0.049). Inactive/higher MD tissue was characterized by a significantly higher percentage of stroma and a significantly lower percentage of adipose tissue, with no significant change in epithelial content. Analysis of published gene expression signatures suggested that Inactive/higher MD tissue expressed increased estrogen response and decreased TGF-β signaling. Conclusions By linking novel molecular phenotypes with MD, our results indicate that MD reflects broad transcriptional changes, including changes in both epithelia- and stroma-derived signaling. PMID:23918601

  2. A technique for fabricating single screw-retained implant-supported interim crowns in conjunction with implant surgery.

    PubMed

    McRory, M Eric; Cagna, David R

    2014-06-01

    This article presents an intraoral technique for fabricating single screw-retained implant-supported interim crowns immediately after surgical implant placement in extraction sites. The technique may be used with any implant system that provides a provisional abutment or an open-tray impression coping that can be modified for use as a provisional abutment. PMID:24461941

  3. InSAR analysis of Subsiding Soils: Amherst and surroundings, NY

    NASA Astrophysics Data System (ADS)

    Becker, R.; Sultan, M.; Giese, R.; Guay, B.

    2005-05-01

    Amherst Town (140 km2), a northeast suburb Buffalo, New York, lies in the Erie-Ontario Lake Plain. Residential development in the north and central region is within or underlain by mostly glacial and lacustrine unconsolidated deposits of expansive silty-clay that is extremely soft in some areas. Foundation -related damages caused by horizonatal (lateral pressure) and vertical movement (subsidence) are estimated to affect more than 1000 homeowners. The subsidence is due, in part, to the shrink/swell nature of the clays (primarily illite with some chlorite) that respond to seasonal changes in soil moisture content. Neighborhood -scale subsidence, however, is potentially a concern if the underlying soft clays are dewatering and consolidating. The purpose of this analysis is to determine (1) if a regional subsidence patterns exists and (2) if subsidence corresponds to foundation damages and/or the soft soil regions. Radar interferometry will be used to provide the estimates of areal extent that are highly sought by the community. Interferograms were generated from 18 ERS-1 and ERS-2 scenes that were acquired over the 1992-2003 time period. Results from the 2 pass and 3 pass methods were unsatisfactory, primarily due to the inherent ambiguity related to difficulties in registration and inaccuracies of digital elevation (2 pass) and due to de-correlation over the long period (years) of deformation (3 pass). Our best results which we report here are from the 4 pass method for pairs of scenes that were selected (1992 through 1995) to encompass the wet-dry cycle (1991:wet; 1992-1995: dry). Good coherence was limited to interferograms generated from pairs of scenes that were acquired over short time periods and small spatial baselines (δT 1 day, Bperp < 50m), in periods of minimal vegetation (November scenes), and in subsets of images acquired with slightly longer temporal and spatial baselines (δT < 3months, Bperp < 200m) over developed areas. Inspection of the patterns

  4. Reliability and failure modes of implant-supported zirconium-oxide fixed dental prostheses related to veneering techniques

    PubMed Central

    Baldassarri, Marta; Zhang, Yu; Thompson, Van P.; Rekow, Elizabeth D.; Stappert, Christian F. J.

    2011-01-01

    Summary Objectives To compare fatigue failure modes and reliability of hand-veneered and over-pressed implant-supported three-unit zirconium-oxide fixed-dental-prostheses(FDPs). Methods Sixty-four custom-made zirconium-oxide abutments (n=32/group) and thirty-two zirconium-oxide FDP-frameworks were CAD/CAM manufactured. Frameworks were veneered with hand-built up or over-pressed porcelain (n=16/group). Step-stress-accelerated-life-testing (SSALT) was performed in water applying a distributed contact load at the buccal cusp-pontic-area. Post failure examinations were carried out using optical (polarized-reflected-light) and scanning electron microscopy (SEM) to visualize crack propagation and failure modes. Reliability was compared using cumulative-damage step-stress analysis (Alta-7-Pro, Reliasoft). Results Crack propagation was observed in the veneering porcelain during fatigue. The majority of zirconium-oxide FDPs demonstrated porcelain chipping as the dominant failure mode. Nevertheless, fracture of the zirconium-oxide frameworks was also observed. Over-pressed FDPs failed earlier at a mean failure load of 696 ± 149 N relative to hand-veneered at 882 ± 61 N (profile I). Weibull-stress-number of cycles-unreliability-curves were generated. The reliability (2-sided at 90% confidence bounds) for a 400N load at 100K cycles indicated values of 0.84 (0.98-0.24) for the hand-veneered FDPs and 0.50 (0.82-0.09) for their over-pressed counterparts. Conclusions Both zirconium-oxide FDP systems were resistant under accelerated-life-time-testing. Over-pressed specimens were more susceptible to fatigue loading with earlier veneer chipping. PMID:21557985

  5. Effect of Misfit on Preload Maintenance of Retention Screws of Implant-Supported Prostheses

    NASA Astrophysics Data System (ADS)

    Assunção, Wirley Gonçalves; Dos Santos, Paulo Henrique; Delben, Juliana Aparecida; Gomes, Érica Alves; Barão, Valentim Adelino Ricardo; Tabata, Lucas Fernando

    2009-10-01

    The aim of this study was to evaluate the effect of unilateral misfit at different levels on a crown-implant-retention screw system of implant-supported crowns. Hexagon castable UCLA abutments were cast in Co-Cr alloy to fabricate 48 metallic crowns divided into four groups ( n = 12). Group A: crowns did not present misfit; Groups B, C and D: crowns were fabricated with unilateral misfit of 50, 100, and 200 μm, respectively. The crowns were attached by titanium retention screw with 30 N/cm to external hexagonal osseointegrated implants embedded in acrylic resin. After 2 min, the retention screw of each replica was submitted to detorque evaluation by an analogic torque gauge. Three retention screws were used to perform detorque evaluation at each replica and the procedure was repeated twice with each screw. Each group was submitted to 72 detorque measurements. Data were evaluated by ANOVA and Tukey test ( P < 0.05). All groups exhibited significant decrease ( P < 0.05) in preload and the lowest decrease occurred in Group A. Groups B, C, and D were statistically significant different from Group A ( P < 0.05), but there was no statistically significant difference between Groups B and D ( P > 0.05). Crowns with unilateral misfit presented higher preload decrease than crowns completely fitted to osseointegrated implants.

  6. Effect of neutral zone technique on marginal bone loss around implant-supported overdentures

    PubMed Central

    Darwish, Mahmoud; Nassani, Mohammad Zakaria; Baroudi, Kusai

    2015-01-01

    Aim: The aim of this study was to compare changes in marginal bone height around immediately loaded implants supporting a mandibular overdenture constructed according to the neutral zone technique with changes around overdentures constructed according to the conventional methods. Materials and Methods: Twelve completely edentulous male patients were randomly allocated to two equal groups of patients. Patients in the first group received conventionally constructed complete dentures and patients in the second group received complete dentures constructed using the neutral zone record. All the patients received two single-piece titanium implants placed bilaterally in the mandibular canine regions using flapless surgery, which were then immediately loaded by the dentures. Marginal bone height was radiographically evaluated at baseline and 6, 12, and 18 months after implant loading. Results: There was a significant loss in marginal bone height around the supporting implants in each study group. However, no significant differences in marginal bone height were recorded between the study groups over the observation period (P > 0.05). Conclusion: Marginal bone height changes induced by overdentures constructed with neutral zone technique on immediately loaded implants are not different from those changes induced by overdentures constructed with a conventional method. PMID:26942118

  7. Zygoma implant-supported prosthetic rehabilitation of a patient after subtotal bilateral maxillectomy.

    PubMed

    D'Agostino, Antonio; Antonio, D'Agostino; Procacci, Pasquale; Pasquale, Procacci; Ferrari, Francesca; Trevisiol, Lorenzo; Nocini, Pier Francesco; Francesco, Nocini Pier

    2013-03-01

    This clinical report describes the successful implant-supported prosthetic rehabilitation of a patient who underwent subtotal bilateral maxillectomy for an oral squamous cell carcinoma with a consequent wide defect interesting the whole hard palate and most of the soft palate, causing a large opening that directly connects the oral cavity to the nasal fossa bilaterally. The innovative aspect of this case is represented by the realization of an obturator prosthesis supported by just 3 zygoma implants.The maxillary bone had been largely excised by radical surgery. Despite the resection had a complete oncological success and the patient was free of disease after 24 months' follow-up, the patient experienced severe speech and deglutition deficit due to the iatrogenic large oro-antral communication. Three zygoma implants have been positioned, 2 through the right maxillary bone and, owing the wide lack of bone, just 1 on the left side. No mucogingival surgery was necessary around the zygoma implants. The obturator prosthesis was stabilized by the 3 implants and the patient's oral function as well as quality of life widely improved.The results show that zygoma implants could represent a viable surgical option to obtain a satisfactory oral function rehabilitation even in case of extensive maxillary defect. PMID:23524823

  8. [Patient satisfaction with removable implant-supported prostheses in the edentulous mandible].

    PubMed

    Zitzmann, Nicola U; Marinello, Carlo P

    2006-01-01

    The aim of the present study was to investigate patients' satisfaction with removable implant restorations with two or four implants compared to a complete denture (CD) in the edentulous mandible. 20 patients in each group were asked to fill out a questionnaire ("Patient satisfaction related to the prosthetic restoration") before treatment, after six months and three years. With implant restorations, either implant-retained (IRET) or implant-supported (ISUP), greater improvements in prostheses retention and pain reduction were achieved in comparison to complete dentures. In addition, restrictions related to food selection were resolved for most implant patients. Despite great inter-individual differences, there was a tendency for larger improvements of almost all parameters with IRET, except chewing ability, which was rated best with ISUP. Long-term results revealed that patients with ISUP (four implants) assessed prostheses retention with the highest ratings compared to those with IRET and CD (p = 0,0147). These results indicate that an improvement in functional and psychological parameters can be achieved with two implants, whilst stabilization with four implants improves prosthesis retention, chewing ability and pain reduction in the long term. Maintenance efforts were more complex for implant restorations than for CD and imply a recall at least once a year. PMID:16610459

  9. Effect of Vertical Misfit on Screw Joint Stability of Implant-Supported Crowns

    NASA Astrophysics Data System (ADS)

    Assunção, Wirley Gonçalves; Delben, Juliana Aparecida; Tabata, Lucas Fernando; Barão, Valentim Adelino Ricardo; Gomes, Érica Alves

    2011-08-01

    The passive fit between prosthesis and implant is a relevant factor for screw joint stability and treatment success. The aim of this study was to evaluate the influence of vertical misfit in abutment-implant interface on preload maintenance of retention screw of implant-supported crowns. The crowns were fabricated with different abutments and veneering materials and divided into 5 groups ( n = 12): Gold UCLA abutments cast in gold alloy veneered with ceramic (Group I) and resin (Group II), UCLA abutments cast in titanium veneered with ceramic (Group III) and resin (Group IV), and zirconia abutments with ceramic veneering (Group V). The crowns were attached to implants by gold retention screws with 35-N cm insertion torque. Specimens were submitted to mechanical cycling up to 106 cycles. Measurements of detorque and vertical misfit in abutment-implant interface were performed before and after mechanical cycling. ANOVA revealed statistically significant difference ( P < 0.05) among groups for vertical misfit measured before and after mechanical cycling. The abutments cast in titanium exhibited the highest misfit values. Pearson correlation test did not demonstrate significant correlation ( P > 0.05) between vertical misfit and detorque value. It was concluded that vertical misfit did not influence torque maintenance and the abutments cast in titanium exhibited the highest misfit values.

  10. Clinical Advantages and Limitations of Monolithic Zirconia Restorations Full Arch Implant Supported Reconstruction: Case Series

    PubMed Central

    Carames, Joao; Yu, Yung Cheng Paul; Pérez, Alejandro; Kang, Mary

    2015-01-01

    Purpose. The purpose of this retrospective case series is to evaluate the clinical advantages and limitations of monolithic zirconia restorations for full arch implant supported restorations and report the rate of complications up to 2 years after insertion. Materials and Methods. Fourteen patients received implant placement for monolithic zirconia full arch reconstructions. Four implants were placed in seven arches, eleven arches received six implants, two arches received seven implants, two arches received eight implants, and one arch received nine implants. Results. No implant failures or complications were reported for an implant survival rate of 100% with follow-up ranging from 3 to 24 months. Conclusions. Monolithic zirconia CAD-/CAM-milled framework restorations are a treatment option for full arch restorations over implants, showing a 96% success rate in the present study. Some of the benefits are accuracy, reduced veneering porcelain, and minimal occlusal adjustments. The outcome of the present study showed high success in function, aesthetics, phonetics, and high patient satisfaction. PMID:26124835

  11. Performance of attachments used in implant-supported overdentures: review of trends in the literature.

    PubMed

    Lee, Damian J

    2013-02-01

    The purpose of this review is to examine the performance of attachments used in implant-supported overdenture (IOD) in both clinical and in vitro settings and report the compiled findings, comparisons, and trends in the research literature. Articles published in PubMed on IOD attachment systems and performance were reviewed. Non-original articles were excluded. For each article included, the type of study, number of implants, number of attachment systems, and study outcome were recorded. Of the 283 articles found, 158 met the inclusion criteria. Ninety-four articles were clinical studies and 64 articles were in vitro studies. Studies on retention were the most common for in vitro studies, and four or more attachment systems were compared in most articles with significant differences in outcome. A clinical outcome of one attachment system was most common for clinical studies, while most studies had neutral outcomes overall. Ball attachment was the most commonly tested IOD attachment system. The trend in the literature showed that there is a large discrepancy between the study designs and outcomes between the clinical and the in vitro studies for IOD. Further clinical studies that can validate in vitro research should be encouraged to address this discrepancy between the two areas. PMID:23509021

  12. Performance of attachments used in implant-supported overdentures: review of trends in the literature

    PubMed Central

    2013-01-01

    The purpose of this review is to examine the performance of attachments used in implant-supported overdenture (IOD) in both clinical and in vitro settings and report the compiled findings, comparisons, and trends in the research literature. Articles published in PubMed on IOD attachment systems and performance were reviewed. Non-original articles were excluded. For each article included, the type of study, number of implants, number of attachment systems, and study outcome were recorded. Of the 283 articles found, 158 met the inclusion criteria. Ninety-four articles were clinical studies and 64 articles were in vitro studies. Studies on retention were the most common for in vitro studies, and four or more attachment systems were compared in most articles with significant differences in outcome. A clinical outcome of one attachment system was most common for clinical studies, while most studies had neutral outcomes overall. Ball attachment was the most commonly tested IOD attachment system. The trend in the literature showed that there is a large discrepancy between the study designs and outcomes between the clinical and the in vitro studies for IOD. Further clinical studies that can validate in vitro research should be encouraged to address this discrepancy between the two areas. PMID:23509021

  13. The paradox of uranium development: A Polanyian analysis of social movements surrounding the Pinon Ridge Uranium Mill

    NASA Astrophysics Data System (ADS)

    Malin, Stephanie A.

    Renewal of nuclear energy development has been proposed as one viable solution for reducing greenhouse gas emissions and impacts of climate change. This discussion became concrete as the first uranium mill proposed since the end of the Cold War, the Pinon Ridge Uranium Mill, received state permits in January 2011 to process uranium in southwest Colorado's Paradox Valley. Though environmental contamination from previous uranium activity caused one local community to be bulldozed to the ground, local support for renewed uranium activity emerges among local residents in communities like Nucla, Naturita, and Bedrock, Colorado. Regionally, however, a coalition of organized, oppositionbased grassroots groups fights the decision to permit the mill. Combined, these events allow social scientists a natural laboratory through which to view social repercussions of nuclear energy development. In this dissertation, I use a Polanyian theoretical framework to analyze social, political-economic, and environmental contexts of social movements surrounding PR Mill. My overarching research problem is: How might Polanyian double movement theory be applied to and made empirically testable within the social and environmental context of uranium development? I intended this analysis to inform energy policy debates regarding renewable energy. In Chapter 1, I found various forms of social dislocation lead to two divergent social movement outcomes. Economic social dislocation led to strong mill support among most local residents, according to archival, in-depth interview, and survey data. On the other hand, residents in regional communities experienced two other types of social dislocation -- another kind of economic dislocation, related to concern over boom-bust economies, and environmental health dislocations related to uranium exposure, creating conditions for a regional movement in opposition to PR Mill. In Chapter 2, I focus on regulations and find that two divergent social movements

  14. A Genetic and Molecular Analysis of the 46c Chromosomal Region Surrounding the Fmrfamide Neuropeptide Gene in Drosophila Melanogaster

    PubMed Central

    O'Brien, M. A.; Roberts, M. S.; Taghert, P. H.

    1994-01-01

    We have analyzed the FMRFamide neuropeptide gene region of Drosophila melanogaster. This gene maps to the 46C region of chromosome 2R; this interval previously was not well characterized. For this genetic and molecular analysis, we have used X-ray mutagenesis, EMS mutagenesis, and the recently reported local P element transposition method. We identified four overlapping deletions, two of which have proximal breakpoints that define a 50-60-kb region surrounding the FMRFamide gene in 46C. To this small region, we mapped three lethal complementation groups; 10 additional lethal complementation groups were mapped to more distal regions of 46CD. One of these groups corresponds to even-skipped, the other 12 are previously unidentified. Using various lines of evidence we excluded the possibility that FMRFamide corresponds to any of the three lethal complementation groups mapping to its immediate 50-60-kb vicinity. The positions of two of the three lethal complementation groups were identified with P elements using a local transposition scheme. The third lethal complementation group was excluded as being FMRFamide mutants by sequence analysis and by immunocytochemistry with proFMRFamide precursor-specific antibodies. This analysis has (1) provided a genetic map of the 46CD chromosomal region and a detailed molecular map of a portion of the 46C region and (2) provided additional evidence of the utility of local transposition for targeting nearby genes. PMID:8056304

  15. Retentiveness of various luting agents used with implant-supported prosthesis: an in vitro study.

    PubMed

    Garg, Pooja; Pujari, Malesh; Prithviraj, D R; Khare, Sumit

    2014-12-01

    Desired retrievability of cemented implant-supported fixed prosthesis makes the retentive strength of cementing agents an important consideration. The aim of the study was to evaluate the retentiveness of purposely designed implant cement and compare its retentiveness with dental cements that are commonly used with implant systems. Ten implant analogs were embedded in auto-polymerizing acrylic resin blocks and titanium abutments were attached to them. Fifty standardized copings were waxed directly on the abutment and casted. The cements used were: (1) resin-bonded zinc oxide eugenol cement, (2) purposely designed implant cement, (3) zinc phosphate cement, (4) zinc polycarboxylate cement, and (5) glass ionomer cement. After cementation, each sample was subjected to a pull-out test using universal testing machine and loads required to remove the crowns were recorded. The mean values and standard deviations of cement failure loads were analyzed using ANOVA and Bonferroni test. The mean values (± SD) of loads at failure (n = 10) for various cements were as follows (N): resin-bonded zinc oxide eugenol cement 394.62 (± 9.76), Premier implant cement 333.86 (± 18.91), zinc phosphate cement 629.30 (± 20.65), zinc polycarboxylate cement 810.08 (± 11.52), and glass ionomer cement 750.17 (± 13.78). The results do not suggest that one cement type is better than another, but they do provide a ranking order of the cements regarding their ability to retain the prosthesis and facilitate easy retrievability. PMID:25506659

  16. RETENTIVENESS OF VARIOUS LUTING AGENTS USED WITH IMPLANT SUPPORTED- PROSTHESIS: AN INVITRO STUDY.

    PubMed

    Garg, Pooja; Pujari, Malesh L; D R, Prithviraj; Khare, Sumit

    2014-03-01

    Abstract ABSTRACT:Purpose: Desired retrievability of cemented implant-supported fixed prosthesis makes the retentive strength of cementing agents an important consideration. The aim of the study was to evaluate the retentiveness of purposely-designed implant cement and to compare its retentiveness with dental cements that are commonly used with implant systems.Materials and method: Ten implant analogs were embedded in auto-polymerizing acrylic resin blocks and titanium abutments were attached to them. 50 standardized copings were waxed directly on the abutment and casted. The cements used were: 1. resin-bonded zinc oxide eugenol cement (Kalzinol, DPI), 2. purposely-designed implant cement (Premier implant cement), 3. zinc phosphate cement (DeTrey Zinc, Dentsply), 4. zinc polycarboxylate cement (Poly-F, Dentsply) and 5. glass ionomer cement (GC Gold Label, GC corporation, Japan). After cementation, each sample was subjected to a pull-out test using universal testing machine and loads required to remove the crowns were recorded. The mean values and standard deviations of cement failure loads were analyzed using ANOVA and Bonferroni test.Results: The mean values (±SD) of loads at failure (n = 10) for various cements were as follows (N): resin-bonded zinc oxide eugenol cement 394.62 (±9.76), Premier implant cement 333.86 (±18.91), zinc phosphate cement 629.30 (±20.65), zinc polycarboxylate cement 810.08 (±11.52) and glass ionomer cement 750.17 (±13.78).Conclusions: The results do not suggest that one cement type is better than another, but they do provide a ranking order of the cements in their ability to retain the prosthesis and to facilitate its easy retrievability. PMID:24588463

  17. Two-piece zirconia implants supporting all-ceramic crowns: A prospective clinical study

    PubMed Central

    Cionca, Norbert; Müller, Nada; Mombelli, Andrea

    2015-01-01

    Objectives The aim of this prospective clinical study is to evaluate the safety and efficacy of a new all-ceramic implant system to replace missing teeth in partially edentulous patients. Material and methods Thirty-two partially edentulous, systemically healthy patients were treated with 49 two-piece zirconia implants (ZERAMEX® T Implant System). Zirconia abutments were connected with adhesive resin cement. Single-unit full-ceramic crowns were cemented. The cases have been followed for 588±174 days after loading (range 369–889 days). All patients have been re-evaluated 1 year after loading. Results The cumulative survival rate 1 year after loading was 87% implants. All failures were the result of aseptic loosening, and no implants were lost after the first year. The results of the other cases were good, and the patients were very satisfied. The cumulative soft tissue complication rate was 0%, the cumulative technical complication rate was 4% implants, the cumulative complication rate for bone loss >2 mm was 0%, and the cumulative esthetic complication rate was 0%. Including the data from 20 patients treated with an earlier version of the system, an over-all 2-year cumulative survival rate of 86% was calculated for a total of 76 two-piece zirconia implants supporting all-ceramic crowns in 52 patients. Conclusions Replacement of single teeth in the posterior area was possible with this new full-ceramic implant system. Failures were due to aseptic loosening. PMID:24666352

  18. Analysis of current density and specific absorption rate in biological tissue surrounding transcutaneous transformer for an artificial heart.

    PubMed

    Shiba, Kenji; Nukaya, Masayuki; Tsuji, Toshio; Koshiji, Kohji

    2008-01-01

    This paper reports on the current density and specific absorption rate (SAR) analysis of biological tissue surrounding an air-core transcutaneous transformer for an artificial heart. The electromagnetic field in the biological tissue is analyzed by the transmission line modeling method, and the current density and SAR as a function of frequency, output voltage, output power, and coil dimension are calculated. The biological tissue of the model has three layers including the skin, fat, and muscle. The results of simulation analysis show SARs to be very small at any given transmission conditions, about 2-14 mW/kg, compared to the basic restrictions of the International Commission on nonionizing radiation protection (ICNIRP; 2 W/kg), while the current density divided by the ICNIRP's basic restrictions gets smaller as the frequency rises and the output voltage falls. It is possible to transfer energy below the ICNIRP's basic restrictions when the frequency is over 250 kHz and the output voltage is under 24 V. Also, the parts of the biological tissue that maximized the current density differ by frequencies; in the low frequency is muscle and in the high frequency is skin. The boundary is in the vicinity of the frequency 600-1000 kHz. PMID:18232363

  19. Factor analysis of rock, soil and water geochemical data from Salem magnesite mines and surrounding area, Salem, southern India

    NASA Astrophysics Data System (ADS)

    Satyanarayanan, M.; Eswaramoorthi, S.; Subramanian, S.; Periakali, P.

    2016-04-01

    Geochemical analytical data of 15 representative rock samples, 34 soil samples and 55 groundwater samples collected from Salem magnesite mines and surrounding area in Salem, southern India, were subjected to R-mode factor analysis. A maximum of three factors account for 93.8 % variance in rock data, six factors for 84 % variance in soil data, five factors for 71.2 % in groundwater data during summer and six factors for 73.7 % during winter. Total dissolved solids are predominantly contributed by Mg, Na, Cl and SO4 ions in both seasons and are derived from the country rock and mining waste by dissolution of minerals like magnesite, gypsum, halite. The results also show that groundwater is enriched in considerable amount of minor and trace elements (Fe, Mn, Ni, Cr and Co). Nickel, chromium and cobalt in groundwater and soil are derived from leaching of huge mine dumps deposited by selective magnesite mining activity. The factor analysis on trivalent, hexavalent and total Cr in groundwater indicates that most of the Cr in summer is trivalent and in winter hexavalent. The gradational decrease in topographical elevation from northern mine area to the southern residential area, combined regional hydrogeological factors and distribution of ultramafic rocks in the northern part of the study area indicate that these toxic trace elements in water were derived from mine dumps.

  20. Field-mapping and petrographic analysis of volcanoes surrounding the Lake Natron Homo sapiens footprint site, northern Tanzania

    NASA Astrophysics Data System (ADS)

    Hewitt, S. M.; Zimmer, B.; Liutkus, C.; Carmichael, S. K.; McGinnis, K.

    2010-12-01

    The Lake Natron Homo sapiens footprint site is located in northern Tanzania along the East African Rift escarpment. The site is positioned south of Lake Natron within an ephemeral channel of the Engare Sero River. The hominid footprints are preserved in a tuff, which originated from one of the volcanic centers surrounding the site. Two large volcanoes in the surrounding region, including the active carbonatite producing Oldoinyo L’engai and the now extinct Kerimasi are possible sources. This area also contains over 30 smaller tuff cones and tuff rings that have been poorly mapped and not analyzed in detail. The site is significant as it is the oldest modern human trackway in East Africa and one of the largest collections of hominid footprints in the world. Determining the source of the footprinted volcanic ash requires detailed field mapping, and both petrographic and geochemical analyses. Extensive field-mapping of the region revealed multiple regional beds that stratigraphically overlay the footprinted layer. Age dating as well as geochemical analysis is being conducted to relate these beds to the footprinted layer. Field-mapping showed that the footprinted tuff is over 35 cm thick, suggesting a large, sustained eruption. The bulk of the tuff cones examined in the field visibly varied in composition to the footprinted tuff and, based on proximity to the footprint site, are too small to produce the requisite volume of ash. Field analysis of samples collected from Oldoinyo L’engai reveal the most similar mineral assemblages to the footprinted layer, and the large volcano provides a source substantial enough to create a thick ash bed 10 km north of the summit. Preliminary research reveals that the footprinted tuff is a phonolite, characterized by silica depletion and the presence of sanidine, augite, and annite with interstitial calcite. XRD analysis of samples collected from Oldoinyo L’engai reveal a nepheline-rich phonolite with zeolites (ie. phillipsite

  1. Large-scale automated image analysis for computational profiling of brain tissue surrounding implanted neuroprosthetic devices using Python.

    PubMed

    Rey-Villamizar, Nicolas; Somasundar, Vinay; Megjhani, Murad; Xu, Yan; Lu, Yanbin; Padmanabhan, Raghav; Trett, Kristen; Shain, William; Roysam, Badri

    2014-01-01

    In this article, we describe the use of Python for large-scale automated server-based bio-image analysis in FARSIGHT, a free and open-source toolkit of image analysis methods for quantitative studies of complex and dynamic tissue microenvironments imaged by modern optical microscopes, including confocal, multi-spectral, multi-photon, and time-lapse systems. The core FARSIGHT modules for image segmentation, feature extraction, tracking, and machine learning are written in C++, leveraging widely used libraries including ITK, VTK, Boost, and Qt. For solving complex image analysis tasks, these modules must be combined into scripts using Python. As a concrete example, we consider the problem of analyzing 3-D multi-spectral images of brain tissue surrounding implanted neuroprosthetic devices, acquired using high-throughput multi-spectral spinning disk step-and-repeat confocal microscopy. The resulting images typically contain 5 fluorescent channels. Each channel consists of 6000 × 10,000 × 500 voxels with 16 bits/voxel, implying image sizes exceeding 250 GB. These images must be mosaicked, pre-processed to overcome imaging artifacts, and segmented to enable cellular-scale feature extraction. The features are used to identify cell types, and perform large-scale analysis for identifying spatial distributions of specific cell types relative to the device. Python was used to build a server-based script (Dell 910 PowerEdge servers with 4 sockets/server with 10 cores each, 2 threads per core and 1TB of RAM running on Red Hat Enterprise Linux linked to a RAID 5 SAN) capable of routinely handling image datasets at this scale and performing all these processing steps in a collaborative multi-user multi-platform environment. Our Python script enables efficient data storage and movement between computers and storage servers, logs all the processing steps, and performs full multi-threaded execution of all codes, including open and closed-source third party libraries. PMID:24808857

  2. Implant-supported fixed restoration of post-traumatic mandibular defect accompanied with skin grafting: A clinical report

    PubMed Central

    Noh, Kwantae; Choi, Woo-Jin

    2013-01-01

    Traumatic defects are mostly accompanied by hard and soft tissue loss. This report describes the surgical and prosthetic treatment of a patient with post-traumatic mandibular defect. A split-thickness skin graft was performed prior to implant placement and prefabricated acrylic stent was placed to hold the graft in place. The esthetic and functional demands of the patient were fulfilled by implant-supported screw-retained fixed prosthesis using CAD-CAM technology. PMID:23508120

  3. CLASH: COMPLETE LENSING ANALYSIS OF THE LARGEST COSMIC LENS MACS J0717.5+3745 AND SURROUNDING STRUCTURES

    SciTech Connect

    Medezinski, Elinor; Lemze, Doron; Ford, Holland; Umetsu, Keiichi; Nonino, Mario; Zitrin, Adi; Broadhurst, Tom; Sayers, Jack; Czakon, Nicole; Waizmann, Jean-Claude; Meneghetti, Massimo; Koekemoer, Anton; Coe, Dan; Postman, Marc; Molino, Alberto; Melchior, Peter; Grillo, Claudio; and others

    2013-11-01

    The galaxy cluster MACS J0717.5+3745 (z = 0.55) is the largest known cosmic lens, with complex internal structures seen in deep X-ray, Sunyaev-Zel'dovich effect, and dynamical observations. We perform a combined weak- and strong-lensing analysis with wide-field BVR{sub c} i'z' Subaru/Suprime-Cam observations and 16-band Hubble Space Telescope observations taken as part of the Cluster Lensing And Supernova survey with Hubble. We find consistent weak distortion and magnification measurements of background galaxies and combine these signals to construct an optimally estimated radial mass profile of the cluster and its surrounding large-scale structure out to 5 Mpc h {sup –1}. We find consistency between strong-lensing and weak-lensing in the region where these independent data overlap, <500 kpc h {sup –1}. The two-dimensional weak-lensing map reveals a clear filamentary structure traced by distinct mass halos. We model the lensing shear field with nine halos, including the main cluster, corresponding to mass peaks detected above 2.5σ{sub κ}. The total mass of the cluster as determined by the different methods is M{sub vir} ≈ (2.8 ± 0.4) × 10{sup 15} M{sub ☉}. Although this is the most massive cluster known at z > 0.5, in terms of extreme value statistics, we conclude that the mass of MACS J0717.5+3745 by itself is not in serious tension with ΛCDM, representing only a ∼2σ departure above the maximum simulated halo mass at this redshift.

  4. Analysis of ambient SO 2 concentrations and winds in the complex surroundings of a thermal power plant

    NASA Astrophysics Data System (ADS)

    Mlakar, P.

    2004-11-01

    SO2 pollution is still a significant problem in Slovenia, especially around large thermal power plants (TPPs), like the one at Šoštanj. The Šoštanj TPP is the exclusive source of SO2 in the area and is therefore a perfect example for air pollution studies. In order to understand air pollution around the Šoštanj TPP in detail, some analyses of emissions and ambient concentrations of SO2 at six automated monitoring stations in the surroundings of the TPP were made. The data base from 1991 to 1993 was used when there were no desulfurisation plants in operation. Statistical analyses of the influence of the emissions from the three TPP stacks at different measuring points were made. The analyses prove that the smallest stack (100 m) mainly pollutes villages and towns near the TPP within a radius of a few kilometres. The medium stack's (150 m) influence is noticed at shorter as well as at longer distances up to more than ten kilometres. The highest stack (230 m) pollutes mainly at longer distances, where the plume reaches the higher hills. Detailed analyses of ambient SO2 concentrations were made. They show the temporal and spatial distribution of different classes of SO2 concentrations from very low to alarming values. These analyses show that pollution patterns at a particular station remain the same if observed on a yearly basis, but can vary very much if observed on a monthly basis, mainly because of different weather patterns. Therefore the winds in the basin (as the most important feature influencing air pollution dispersion) were further analysed in detail to find clusters of similar patterns. For cluster analysis of ground-level winds patterns in the basin around the Šoštanj Thermal Power Plant, the Kohonen neural network and Leaders' method were used. Furthermore, the dependence of ambient SO2 concentrations on the clusters obtained was analysed. The results proved that effective cluster analysis can be a useful tool for compressing a huge wind data base

  5. Analysis of the Magnitude and Frequency of Peak Discharge and Maximum Observed Peak Discharge in New Mexico and Surrounding Areas

    USGS Publications Warehouse

    Waltemeyer, Scott D.

    2008-01-01

    Estimates of the magnitude and frequency of peak discharges are necessary for the reliable design of bridges, culverts, and open-channel hydraulic analysis, and for flood-hazard mapping in New Mexico and surrounding areas. The U.S. Geological Survey, in cooperation with the New Mexico Department of Transportation, updated estimates of peak-discharge magnitude for gaging stations in the region and updated regional equations for estimation of peak discharge and frequency at ungaged sites. Equations were developed for estimating the magnitude of peak discharges for recurrence intervals of 2, 5, 10, 25, 50, 100, and 500 years at ungaged sites by use of data collected through 2004 for 293 gaging stations on unregulated streams that have 10 or more years of record. Peak discharges for selected recurrence intervals were determined at gaging stations by fitting observed data to a log-Pearson Type III distribution with adjustments for a low-discharge threshold and a zero skew coefficient. A low-discharge threshold was applied to frequency analysis of 140 of the 293 gaging stations. This application provides an improved fit of the log-Pearson Type III frequency distribution. Use of the low-discharge threshold generally eliminated the peak discharge by having a recurrence interval of less than 1.4 years in the probability-density function. Within each of the nine regions, logarithms of the maximum peak discharges for selected recurrence intervals were related to logarithms of basin and climatic characteristics by using stepwise ordinary least-squares regression techniques for exploratory data analysis. Generalized least-squares regression techniques, an improved regression procedure that accounts for time and spatial sampling errors, then were applied to the same data used in the ordinary least-squares regression analyses. The average standard error of prediction, which includes average sampling error and average standard error of regression, ranged from 38 to 93 percent

  6. Fluorine analysis of human dentin surrounding resin composite after fluoride application by μ-PIGE/PIXE analysis

    NASA Astrophysics Data System (ADS)

    Okuyama, Katsushi; Komatsu, Hisanori; Yamamoto, Hiroko; Pereira, Patricia N. R.; Bedran-Russo, Ana K.; Nomachi, Masaharu; Sato, Takahiro; Sano, Hidehiko

    2011-10-01

    The use of fluoride for the prevention of caries is based on the transformation of hydroxylapatite to fluoroapatite in the presence of fluoride ions, thereby strengthening tooth structure. Adhesion of dentin and resin composite (tooth-colored restoration material) requires a dentin bonding system, since resin composite is not able to adhere to dentin directly. Demineralization of dentin by acid etching is an important step in the dentin bonding system, however, demineralization also introduces weaknesses in tooth structure. If the demineralized dentin could be strengthened by the application of fluoride, then the dentin-resin composite bond strength might also improve. To test this hypothesis, the present study evaluated the influence of fluoride applications on the strength of the dentin-resin composite bond by (1) tensile strength testing analyses, (2) SEM analyses of tooth structure, and (3) detection of calcium (Ca) and fluorine (F) distribution patterns by micro proton-induced X-ray emission (μ-PIXE) and micro proton-induced gamma-ray emission (μ-PIGE) analyses conducted at the Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) at the Takasaki Advanced Radiation Research Institute (TARRI). In this study, the dentin in extracted human molars was exposed by grinding and the dentin was etched with 35% phosphoric acid. Fluoride was applied at two concentrations, 0.022% (100 ppm F) and 2.21% (10,000 ppm F) NaF solution, for two time periods, 30 and 60 s, prior to bonding the resin composite with the treated dentin. Controls were prepared in the same manner, but without the fluoride application. Bond strength was measured with a micro-tensile testing unit, and the fluorine and calcium distributions at the interface between dentin and resin composite were detected by μ-PIGE and μ-PIXE analysis, respectively. Results indicate that the 10,000 ppm F applications resulted in higher bond strengths than observed in either the 100 ppm F applications or

  7. Simplified Fabrication of an Esthetic Implant-Supported Crown With a Novel CAD/CAM Glass Ceramic.

    PubMed

    Conejo, Julián; Blatz, Markus B

    2016-06-01

    Implant therapy and CAD/CAM technologies are advancing quickly, providing predictable esthetic and functional treatment options. A recent development involves the use of zirconia-reinforced lithium-silicate ceramic for fabrication of implant-supported restorations. Suitable for monolithic crowns, the material provides the optical advantages of a silicate ceramic with improved physical strength. Several prerequisites, however, are necessary to fabricate screw-retained monolithic restorations in the anterior maxilla. This case report demonstrates the clinical steps to fabricate a monolithic ceramic CAD/CAM crown on an immediately placed dental implant in the esthetic zone. PMID:27517477

  8. Implant-Supported Removable Partial Denture Improves the Quality of Life of Patients with Extreme Tooth Loss.

    PubMed

    Campos, Camila Heitor; Gonçalves, Thais Marques Simek Vega; Garcia, Renata Cunha Matheus Rodrigues

    2015-10-01

    This study aimed to evaluate oral health-related quality of life (OHRQoL) in partially dentate subjects, presenting extreme tooth loss in posterior region with missing post-canines, comparing the use of conventional removable partial dentures (RPDs) and implant-supported RPDs. OHRQoL was measured using the Brazilian version of the Oral Health Impact Profile. Twelve subjects presenting maxillary total and mandibular Kennedy Class I edentulism (mean age 62.6±7.8 years) first received complete maxillary dentures and conventional mandibular free-end RPDs. After two months, the subjects had their OHRQoL assessed. Osseointegrated implants were inserted bilaterally in the mandibular first molar regions, and after four months ball abutments were placed to support the free-end RPD. Two months later, the patients had their OHRQoL reassessed. Wilcoxon signed-rank test was used to evaluate differences in OHRQoL (α=0.05). Results showed improvement in all OHIP-49 domains (p<0.05) after associating implants to the RPD. The mandibular implant-supported free-end RPD significantly improved OHRQoL. PMID:26647929

  9. Influence of Prosthetic Screw Material on Joint Stability in Passive and Non-Passive Implant-Supported Dentures

    PubMed Central

    Spazzin, Aloísio Oro; Henriques, Guilherme Elias Pessanha; de Arruda Nóbilo, Mauro Antônio; Consani, Rafael Leonardo Xediek; Correr-Sobrinho, Lourenço; Mesquita, Marcelo Ferraz

    2009-01-01

    Objectives: This study evaluated the influence of prosthetic screw material on joint stability in implantsupported dentures at two levels of fit. Methods: Ten mandibular implant-supported dentures were fabricated. Twenty cast models were fabricated using these dentures. Four groups (n=10) were tested, according to the vertical fit of the dentures [passive and non-passive] and prosthetic screw materials [titanium (Ti) or gold (Au) alloy]. The one-screw test was performed to quantify the vertical misfits using an optic microscope. The loosening torque for the prosthetic screws was measured 24 hours after the tightening torque (10 Ncm) using a digital torque meter. Data were analyzed by two-way ANOVA and Tukey’s test (α=0.05). Results: Overall, dentures with passive fit and Ti screws resulted in significantly higher loosening torque of the prosthetic screws (p<0.05). No significant interaction was found between fit level and screw material (p=0.199). The prosthetic screw material and fit of implant-supported dentures have an influence on screw joint stability. Ti screws presented higher joint stability than Au screws and minimum of misfit should be found clinically to improve the mechanical behavior of the screw joint. PMID:20148135

  10. Avoiding osseous grafting in the atrophic posterior mandible for implant-supported fixed partial dentures: a report of 2 cases.

    PubMed

    Flanagan, Dennis

    2011-12-01

    Bone atrophy occurs after tooth extraction in the posterior mandible, placing the mandibular canal and its neural, arterial, and venous contents closer to the osseous facial aspect and the coronal crest. This proximity places the structure in danger of damage when dental implants are surgically placed to support fixed or removable prostheses. Several options are available to treat these areas for implant-supported fixed and removable complete or partial dentures. Osseous grafting and ridge expansion are surgical options that enable acceptance of standard sized dental implants but have serious morbidities. Additionally, vertical osseous augmentation is not predictable at this time. Narrow diameter dental implants can be placed to avoid the mandibular canal, but some bone volume situations preclude this. Very wide and very short (6.5 × 5 mm) dental implants may be placed at an angle in atrophic sites to successfully support fixed partial dentures. An anterior guidance occlusal scheme may be used in maxillary dentate patients or group function in maxillary complete denture patients. A 100 micron occlusal relief in fixed partial dentures in dentate patients may be required to account for natural tooth intrusion and to prevent occlusal overload of the implant-supported partial denture. PMID:20925498

  11. The impact on bone tissues of immediate implant-supported mandibular overdentures with cusped and cuspless teeth

    PubMed Central

    Arafa, Khalid A.

    2016-01-01

    Objectives: To examine the effects on bone tissues of immediate implant-supported mandibular overdentures with cusped or cuspless teeth. Methods: A randomized controlled trial was conducted at the Dental Clinic, Faculty of Dentistry, Al-Azhar University, Assiut Branch, Egypt, over a 12-month period from September 2013 to September 2014. Twenty patients were treated with immediate implant-supported overdentures: one group received overdentures with cusped teeth, and the other group received overdentures with cuspless teeth. The rate of implant success was assessed clinically and radiographically at 3, 6, 9, and 12 months. The data were collected by a questionnaire, an observation checklist, and radiography. The data were then analyzed using computerized methods. Results: Overdentures with cusped teeth showed a significant improvement in the clinical criteria, including the absence of clinical implant mobility, pain, and bone resorption, while the clinical criteria for the absence of peri-implant radiolucency were insignificantly different between the 2 groups (p>0.05). There were no significant differences in the clinical evaluations for bone levels at the time of insertion or 3 months after insertions, while significant differences were found at 6, 9, and 12 months after insertion. Conclusion: Overdentures with cusped teeth supported by immediate implants were found superior regarding many clinical criteria than those cuspless counterparts. PMID:26739979

  12. Effect of attachment type on load distribution to implant abutments and the residual ridge in mandibular implant-supported overdentures

    PubMed Central

    Matsudate, Yoshiki; Abue, Masaru; Hong, Guang; Sasaki, Keiichi

    2015-01-01

    This study aimed to investigate the effect of attachment type on the load transmitted to implants and the residual ridge in a mandibular two-implant-supported overdenture in a model study. Ball attachments, locator attachments, and round-bar attachments were selected and examined. Static and dynamic vertical loads of 100 N were applied in the right first molar region. The load on the implants was measured by piezoelectric three-dimensional force transducers, and the load on the residual ridge beneath the denture base was measured using a tactile sheet sensor. The load on the implants with ball attachments was significantly higher than that with the other two attachments. The load on the residual ridge with round-bar attachments was significantly higher than that with the other two attachments. Our findings indicate that the three-dimensional load on implants and the residual ridge beneath the denture base is significantly associated with the type of attachment used in implant-supported overdentures. PMID:25798201

  13. [Observations and comparison analysis of air pollution in Beijing and nearly surrounding areas during Beijing 2008 Olympic Games].

    PubMed

    Sun, Zhi-Qiang; Ji, Dong-Sheng; Song, Tao; Lin, Hong; Wang, Yue-Si; Jiang, Chang-Sheng

    2010-12-01

    In order to study regional air quality, evaluate the interaction of air quality among Beijing and four cities and assess the effects of regional collaborative emission abatement in Beijing and surrounding areas for the Olympic Games period on regional air quality, and seek an effective means of early warning of air pollution, a monitoring network on observation of atmospheric pollutants in Beijing and four nearby cities which were Zhuozhou, Langfang, Xianghe and Yanjiao, was established to measure concentrations of NO(x), O3 and particulate matter in June 2008. The results show that the primary pollutants in Beijing and nearly surrounding areas are particulates during the study periods. The average mass concentrations of PM10 were (114 +/- 66) microg/m3 and (128 +/- 59) microg/m3 in Beijing and nearby cities, respectively, while the average mass concentrations of PM2.5 were (77 +/- 47) microg/m3 and (81 +/- 51) microg/m3, respectively. The average maximum hourly mass concentrations of O3 were (164 +/- 52) microg/m3 and (165 +/- 55) microg/m3, as well as the average mass concentrations of NO(x) were (58 +/- 23) microg/m3 and (25 +/- 14) microg/m3 in Beijing and nearby cities, respectively. Compared to June, concentrations of PM10, PM2.5, O3, NO(x) decreased by 69%, 62%, 18% and 41% during the Olympic period (from August 8 to 24) and 56%, 49%, 17% and 16% during the Paralympic Games period (from September 6 to 17) in Beijing. The mass concentration of PM2.5 was affected by the surrounding areas of Beijing seriously. The relative high concentrations of NO(x) in Beijing implied NO(x) had the potential tendency to be transported to the surrounding areas. Ozone showed regional pollution characteristics in summer. It shows that the monitoring network on observation of atmospheric pollutants in Beijing and nearly surrounding areas is significant in early warning of air pollution, and could provide scientific support for interregional cooperation of air pollution control

  14. Analysis of airborne microorganisms, MVOC and odour in the surrounding of composting facilities and implications for future investigations.

    PubMed

    Fischer, Guido; Albrecht, Andreas; Jäckel, Udo; Kämpfer, Peter

    2008-03-01

    Emission and dispersal of microorganisms and odours from composting facilities were studied in a 3-year project at nine different composting facilities in Germany. Measurements were carried out under so-called 'normal-case', i.e. typical local climate conditions and working activities within the facilities, and 'real worst-case' conditions ('drainage flow' conditions) being characterized by the translocation of cold air mostly at night, and containing large amounts of bioaerosols. Highest concentrations of microorganisms were observed during turning of compost with a maximum of 2.4x10(6)cfu m(-3) for thermophilic actinomycetes. Other groups of microorganisms were detected in concentrations of about 10(5)cfu m(-3). During shredding of fresh organic material, the concentrations of all microorganisms reached 10(4)cfu m(-3). Here, odour concentrations turned out to be highest (up to 1,367 odour units (OU)m(-3)). At facilities equipped with a biofilter (odour reduction), a decrease in OU by a factor of 10 was observed. In the surrounding of the facilities, highest concentrations ranged between 10(1)-10(3)cfu m(-3) upwind and from 10(1)-10(4)cfu m(-3) downwind. The specific local meteorological situations must be considered carefully in advance and during sampling. Especially 'drainage flow' situations can lead to high microorganism concentrations (>10(4)-10(5)cfu m(-3) of thermophilic actinomycetes and thermophilic fungi) in the surroundings of composting facilities. PMID:17936684

  15. Randomized Clinical Trial of Implant-Supported Ceramic-Ceramic and Metal-Ceramic Fixed Dental Prostheses: Preliminary Results

    PubMed Central

    Esquivel-Upshaw, Josephine F.; Clark, Arthur E.; Shuster, Jonathan J.; Anusavice, Kenneth J.

    2013-01-01

    Purpose The aim of this study was to determine the survival rates over time of implant-supported ceramic-ceramic and metal-ceramic prostheses as a function of core-veneer thickness ratio, gingival connector embrasure design, and connector height. Materials and Methods An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study involving 55 patients missing three teeth in either one or two posterior areas. These patients (34 women; 21 men; age range 52–75 years) were recruited for the study to receive a 3-unit implant-supported fixed dental prosthesis (FDP). Two implants were placed for each of the 72 FDPs in the study. The implants (Osseospeed, Astra Tech), which were made of titanium, were grit blasted. A gold-shaded, custom-milled titanium abutment (Atlantis, Astra Tech), was secured to each implant body. Each of the 72 FDPs in 55 patients were randomly assigned based on one of the following options: (1) A. Material: ceramic-ceramic (Yttria-stabilized zirconia core, pressable fluorapatite glass-ceramic, IPS e.max ZirCAD and ZirPress, Ivoclar Vivadent) B. metal-ceramic (palladium-based noble alloy, Capricorn, Ivoclar Vivadent, with press-on leucite-reinforced glass-ceramic veneer, IPS InLine POM, Ivoclar Vivadent); (2) occlusal veneer thickness (0.5, 1.0, and 1.5 mm); (3) curvature of gingival embrasure (0.25, 0.5, and 0.75 mm diameter); and (4) connector height (3, 4, and 5 mm). FDPs were fabricated and cemented with dual-cure resin cement (RelyX, Universal Cement, 3M ESPE). Patients were recalled at 6 months, 1 year, and 2 years. FDPs were examined for cracks, fracture, and general surface quality. Results Recall exams of 72 prostheses revealed 10 chipping fractures. No fractures occurred within the connector or embrasure areas. Two-sided Fisher’s exact tests showed no significant correlation between fractures and type of material system (p = 0.51), veneer thickness (p = 0.75), radius of curvature of gingival embrasure

  16. Importance of a distal proximal contact on load transfer by implant-supported single adjacent crowns in posterior region of the mandible: a photoelastic study

    PubMed Central

    de AGUIAR JÚNIOR, Fábio Afrânio; TIOSSI, Rodrigo; MACEDO, Ana Paula; de MATTOS, Maria da Gloria Chiarello; RIBEIRO, Ricardo Faria; RODRIGUES, Renata Cristina Silveira

    2013-01-01

    Objective This study aimed to evaluate the importance of a distal proximal contact on the load transfer to the posterior region of the mandible by non-splinted adjacent implant-supported crowns using photoelastic stress analysis. Material and Methods A rectangular model (68x30x15 mm) was made of polymethylmethacrylate resin to simulate half of the mandibular arch. One model was completed with resin replicas representing the first premolar and second molar and with two 3.75 mm dia.x11 mm internal hexagon threaded implants replacing the second premolar and first molar. The other model was manufactured in the same way but without the second molar. Both models were duplicated using photoelastic resin. The roots of the teeth replicas were covered with a layer of polyether impression material to simulate the periodontal ligament. Two different vertical loads were applied to the crowns as follows: 1 - single static point load alternately applied to the crowns replacing the second premolar and first molar (50 N); 2 - simultaneous static point loads applied to both of the crowns replacing the second premolar and first molar (100 N). The resulting isochromatic fringe pattern in the photoelastic model was monitored and photographed. Results All loading conditions studied showed that the presence of the second molar has changed the load transmission and the pattern of stresses. Conclusion Results showed that the presence of a second molar proximal contact can help minimize the stresses around the implants. PMID:24212984

  17. Effect of cement washout on loosening of abutment screws and vice versa in screw- and cement- retained implant-supported dental prosthesis

    PubMed Central

    Kim, Seok-Gyu; Son, Mee-Kyoung

    2015-01-01

    PURPOSE The purpose of this study was to examine the abutment screw stability of screw- and cement-retained implant-supported dental prosthesis (SCP) after simulated cement washout as well as the stability of SCP cements after complete loosening of abutment screws. MATERIALS AND METHODS Thirty-six titanium CAD/CAM-made implant prostheses were fabricated on two implants placed in the resin models. Each prosthesis is a two-unit SCP: one screw-retained and the other cemented. After evaluating the passive fit of each prosthesis, all implant prostheses were randomly divided into 3 groups: screwed and cemented SCP (Control), screwed and noncemented SCP (Group 1), unscrewed and cemented SCP (Group 2). Each prosthesis in Control and Group 1 was screwed and/or cemented, and the preloading reverse torque value (RTV) was evaluated. SCP in Group 2 was screwed and cemented, and then unscrewed (RTV=0) after the cement was set. After cyclic loading was applied, the postloading RTV was measured. RTV loss and decementation ratios were calculated for statistical analysis. RESULTS There was no significant difference in RTV loss ratio between Control and Group 1 (P=.16). No decemented prosthesis was found among Control and Group 2. CONCLUSION Within the limits of this in vitro study, the stabilities of SCP abutment screws and cement were not significantly changed after simulated cement washout or screw loosening. PMID:26140172

  18. Occlusion for implant-supported fixed dental prostheses in partially edentulous patients: a literature review and current concepts

    PubMed Central

    Sukotjo, Cortino

    2013-01-01

    Implant treatment has become the treatment of choice to replace missing teeth in partially edentulous areas. Dental implants present different biological and biomechanical characteristics than natural teeth. Occlusion is considered to be one of the most important factors contributing to implant success. Most literature on implant occlusal concepts is based on expert opinion, anecdotal experiences, in vitro and animal studies, and only limited clinical research. Furthermore, scientific literature regarding implant occlusion, particularly in implant-supported fixed dental prostheses remains controversial. In this study, the current status of implant occlusion was reviewed and discussed. Further randomized clinical research to investigate the correlation between implant occlusion, the implant success rate, and its risk factors is warranted to determine best clinical practices. PMID:23678387

  19. Reducing Distortion of Implant- or Abutment-Level Impressions for Implant-Supported Prosthetic Rehabilitation: A Technique Report.

    PubMed

    Lanis, Alejandro; Padial-Molina, Miguel; Selman, Andrea; Alvarez Del Canto, Orlando

    2015-01-01

    Passive fit between prosthesis and implants or abutments is a significant factor in preventing mechanical and biologic failures of implant-supported prostheses. Therefore, impression techniques must transfer the 3D implant position as accurately as possible for a correct superstructure fabrication. A novel impression protocol that uses an individualized open tray design is proposed. It allows the clinician to splint the transfers between the copings, outside the impression area, and to the tray itself to create a rigid monoblock. Thus, distortions produced by the tear of impression material or by transfer abutments' micromovements during tray retrieval are limited and superstructure misfits are minimized. This technique is specifically recommended for long spanning or completely edentulous patients. PMID:26509993

  20. Loss of teeth in positions mesially adjacent to implant-supported fixed dentures: a retrospective clinical survey.

    PubMed

    Yoshino, Koichi; Nishibori, Masakazu; Fujiseki, Masatsugu; Ito, Koji; Kuroda, Masahiko; Matsukubo, Takashi

    2015-01-01

    The aim of this study was to investigate the loss of teeth in positions mesially adjacent to implant-supported fixed dentures (IFDs) after insertion of IFDs in unilateral free-end edentulous spaces in the mandible at dental clinics. There were a total of 157 adjacent teeth. Nine adjacent teeth (5.73%, 9 of 157), 9 opposing teeth (2.59%, 9 of 348), 38 posterior teeth (1.93%, 38 of 1,964), and 3 anterior teeth (0.22%, 3 of 1,380) were lost during the observation period. The percentage of lost adjacent teeth was higher than that of posterior teeth (P = .002). Teeth in positions adjacent to the IFDs require more attention than other remaining teeth. PMID:25822301

  1. Dynamic Abutment: A method of redirecting screw access for implant-supported restorations: Technical details and a clinical report.

    PubMed

    Berroeta, Eva; Zabalegui, Ion; Donovan, Terrence; Chee, Winston

    2015-06-01

    The esthetic outcome of implant-supported restorations is affected by the implant position. A well-placed implant will allow appropriate contours of the restoration and together with an adequate volume of soft tissue will result in a functional and esthetic restoration. When a screw-retained restoration is anticipated, an implant that is angled too far facially would be esthetically unacceptable. In 2004, an abutment called the Dynamic Abutment (Talladium International Implantology) became commercially available. This abutment can allow a deviation of the restoration screw access angle to the implant angle of up to 28 degrees while allowing a screw-retained restoration to be connected directly to the platform of the implant. The purpose of this article was to describe the components, technique, and clinical use of this abutment. PMID:25794919

  2. Occlusion for implant-supported fixed dental prostheses in partially edentulous patients: a literature review and current concepts.

    PubMed

    Yuan, Judy Chia-Chun; Sukotjo, Cortino

    2013-04-01

    Implant treatment has become the treatment of choice to replace missing teeth in partially edentulous areas. Dental implants present different biological and biomechanical characteristics than natural teeth. Occlusion is considered to be one of the most important factors contributing to implant success. Most literature on implant occlusal concepts is based on expert opinion, anecdotal experiences, in vitro and animal studies, and only limited clinical research. Furthermore, scientific literature regarding implant occlusion, particularly in implant-supported fixed dental prostheses remains controversial. In this study, the current status of implant occlusion was reviewed and discussed. Further randomized clinical research to investigate the correlation between implant occlusion, the implant success rate, and its risk factors is warranted to determine best clinical practices. PMID:23678387

  3. Microfractures in metal-ceramic and all-ceramic implant-supported fixed dental prostheses caused by superstructure fixation.

    PubMed

    Karl, Matthias; Graef, Friedrich; Wichmann, Manfred; Beck, Nina

    2012-01-01

    The effect of ceramic veneering on the passivity of fit of cast metal and CAD/CAM-fabricated zirconia ceramic implant-supported three-unit cement-retained restorations was investigated, as well as the effect of misfit stress on the marginal integrity of ceramic veneers. Superstructures were fabricated using cast metal or by CAD/CAM milling of presintered or HIP zirconia ceramic (n=10). Before and after veneering, strain gages were used to measure in vitro the strain developed in all the restorations as a result of superstructure fixation. Fluorescent penetrant method was used to detect microcracks developed in ceramic veneers. Cast frameworks showed significantly higher strain values than CAD/CAM frameworks (p=0.000). Veneering significantly increased strain development in all CAD/CAM frameworks (p=0.000). Compared to zirconia ceramic restorations, significantly more microcracks were observed in cast restorations (p=0.000) both before and after superstructure fixation. PMID:22673463

  4. Transdisciplinary treatment of Class III malocclusion using conventional implant-supported anchorage: 10-year posttreatment follow-up

    PubMed Central

    Rinaldi, Mariana Roennau Lemos; Rizzatto, Susana Maria Deon; de Menezes, Luciane Macedo; Polido, Waldemar Daudt; de Lima, Eduardo Martinelli Santayanna

    2015-01-01

    INTRODUCTION: Combined treatment offers advantages for partially edentulous patients. Conventional implants, used as orthodontic anchorage, enable previous orthodontic movement, which provides appropriate space gain for crown insertion. OBJECTIVE: This case report describes the treatment of a 61-year and 10-month-old patient with negative overjet which made ideal prosthetic rehabilitation impossible, thereby hindering dental and facial esthetics. CASE REPORT: After a diagnostic setup, conventional implants were placed in the upper arch to anchor intrusion and retract anterior teeth. Space gain for lateral incisors was achieved in the lower arch by means of an orthodontic appliance. CONCLUSIONS: Integrated planning combining Orthodontics and Implantology provided successful treatment by means of conventional implant-supported anchorage. The resulting occlusal relationship proved stable after 10 years. PMID:26154459

  5. Maxillary implant-supported bar overdenture and mandibular implant-retained fixed denture using CAD/CAM technology and 3-D design software: a clinical report.

    PubMed

    Spyropoulou, Panagiota-Eirini; Razzoog, Michael E; Duff, Renée E; Chronaios, Dimitrios; Saglik, Berna; Tarrazzi, Daler E

    2011-06-01

    The implant-supported bar overdenture and the implant-retained fixed complete denture are appropriate treatment choices for patients with inadequate bone volume in the posterior maxilla and mandible, respectively. Computer-aided design/computer-aided manufacturing (CAD/CAM) technology has broadened the scope and application of those treatment options, allowing for prosthodontically-driven implant placement and ideal substructure design for optimal esthetics and biomechanics. This report describes the fabrication of a maxillary implant-supported milled titanium bar with attachments and an overdenture, and a mandibular implant-retained fixed complete denture with milled titanium substructure. PMID:21640235

  6. Micromechanical Analysis of the Hyaluronan-Rich Matrix Surrounding the Oocyte Reveals a Uniquely Soft and Elastic Composition.

    PubMed

    Chen, Xinyue; Bonfiglio, Rita; Banerji, Suneale; Jackson, David G; Salustri, Antonietta; Richter, Ralf P

    2016-06-21

    The cumulus cell-oocyte complex (COC) matrix is an extended coat that forms around the oocyte a few hours before ovulation and plays vital roles in oocyte biology. Here, we analyzed the micromechanical response of mouse COC matrix by colloidal-probe atomic force microscopy. We found that the COC matrix is elastic insofar as it does not flow and its original shape is restored after force release. At the same time, the COC matrix is extremely soft. Specifically, the most compliant parts of in vivo and in vitro expanded COC matrices yielded Young's modulus values of 0.5 ± 0.1 Pa and 1.6 ± 0.3 Pa, respectively, suggesting both high porosity and a large mesh size (≥100 nm). In addition, the elastic modulus increased progressively with indentation. Furthermore, using optical microscopy to correlate these mechanical properties with ultrastructure, we discovered that the COC is surrounded by a thick matrix shell that is essentially devoid of cumulus cells and is enhanced upon COC expansion in vivo. We propose that the pronounced nonlinear elastic behavior of the COC matrix is a consequence of structural heterogeneity and serves important functions in biological processes such as oocyte transport in the oviduct and sperm penetration. PMID:27332136

  7. The optimal design of an implant to improve bone quality of implant surroundings based on stress analysis

    NASA Astrophysics Data System (ADS)

    Noyama, Yoshihiro; Nagayama, Noriyuki; Kuramoto, Koichi; Nakano, Takayoshi

    2009-05-01

    Research on how implant surface shape contributes to long-term stability after implantation is important in the field of orthopaedics. In particular, technology that controls various bone quality parameters and voluntary bone inducement in implant surroundings should be developed for the next generation of implants and this will improve the patient's quality of life (QOL). For this research, we focused on the inducement of the appropriate alignment for biological apatite (BAp) crystallites and related collagen (Col.) fibres as a bone quality parameter. In this study, we predicted that when stress is applied to bone, the BAp/Col. preferential alignment can be formed if osteocytes are in an environment that is aligned with the principle stress vector. We tested this idea by introducing grooves in the principal stress direction on the surface of an implant. This work thus analyzes the effect of stress transmission by a load at the proximal femur on the bone inside and near the grooves by using mechanical simulation in which groove angles can be changed on the implant surface. Coordinate data from the mechanical simulation of the combined bone/implant environment was verified against the coordinate data obtained by CT scans of actual canine bone. Results suggest that the tendency of stress transmission differs depending on the position and angle of the grooves and based on a vector diagram of the maximum and minimum principal stresses. The simulation was able to predict bone dynamics in vivo and enabled a best design of an implant to control the BAp/Col. alignment as an index of bone quality.

  8. Molecular analysis of bacterial communities in uranium ores and surrounding soils from Banduhurang open cast uranium mine, India: A comparative study.

    PubMed

    Islam, Ekramul; Dhal, Paltu K; Kazy, Sufia K; Sar, Pinaki

    2011-01-01

    Bacterial community structure of heavy metal rich- uranium ores and surrounding soils was explored using 16S rRNA gene based clone library analysis and denaturing gradient gel electrophoresis (DGGE) to provide baseline microbial diversity data on autochthonous communities. Sequence analysis of major ribotypes and/or DGGE bands revealed Proteobacteria and Acidobacteria as the two most frequently present bacterial phyla across the samples, although relative abundance of each phyla and identity of their members at lower taxonomic level showed marked difference. Gammaproteobacteria (Pseudomonas and Escherichia) was most abundant in U-ore samples along with the lineages of β-Proteobacteria (Burkholderia and Janthinobacterium), α-Proteobacteria (Brevundimonas), Bacteroidetes (Spingobacterium), Firmicutes (Peptoniphilus), Actinobacteria (Corynebacterium), uncultured -Acidobacteria, -Chloroflexi and -Cyanobacterium. In contrast to this soil communities were represented by mixed populations predominated by uncultured Acidobacteria along with Gammaproteobacteria (Succinivibrio, Cellovibrio and Legionella), β-Proteobacteria (Rhodocyclus), α-Proteobacteria (Methylocystis and Phenylobacterium), δ-Proteobacteria, unclassified bacteria, uncultured Bacteroidetes, Firmicutes (Bacillus), Cyanobacteria (Scytonema), Actinobacteria (Actinomadura) and candidate division TM7. Principle Component Analyis (PCA) of geochemical data and UPGMA cluster analysis of DGGE profiles were in close agreement showing characteristic relatedness of samples obtained from either ores or soils. Our analysis indicated that soils surrounding the ore deposit bear specific geochemical as well as microbiologial characteristics distinct from the ore deposit and therefore these data obtained at the onset of mining could serve as a baseline of information to gauge the subsequent environmnetal impact of U-mining. PMID:21308598

  9. Are sectioning and soldering of short-span implant-supported prostheses necessary procedures?

    PubMed

    Bianchini, Marco A; Souza, João G O; Souza, Dircilene C; Magini, Ricardo S; Benfatti, Cesar A M; Cardoso, Antonio C

    2011-01-01

    The aim of this study was to evaluate the fit between dental abutments and the metal framework of a 3-unit fixed prosthesis screwed to two implants to determine whether sectioning and soldering of the framework are in fact necessary procedures. The study was based on a model of a metal framework of a 3-unit prosthesis screwed to two implants. A total of 18 metal frameworks were constructed and divided into 3 groups: (1) NS group - each framework was cast in one piece and not sectioned; (2) CS group - the components of each sectioned framework were joined by conventional soldering; and (3) LW group - the components of each sectioned framework were joined by laser welding. The control group consisted of six silver-palladium alloy copings that were not cast together. Two analyses were mperformed: in the first analysis, the framework was screwed only to the first abutment, and in the second analysis, the framework was screwed to both abutments. The prosthetic fit was assessed at a single point using a measuring microscope (Measurescope, Nikon, Japan) and the marginal gap was measured in micrometers. Statistical analysis was performed using analysis of variance (ANOVA), Scheffe's test, Student's t-test, and Mann-Whitney U test. The NS group had larger marginal gaps than the other groups (p<0.01), while the CS and LW groups had a similar degree of misfit with no significant difference between them. The results revealed that, in the case of short-span 3-unit fixed prostheses, the framework should be sectioned and soldered or welded to prevent or reduce marginal gaps between the metal framework and dental abutments. PMID:22010402

  10. Every Paper Matters: A Comparative Analysis of Two Policies Surrounding the Development of Children and Young People

    ERIC Educational Resources Information Center

    Allan, David

    2010-01-01

    The purpose of this article is to examine two policies in an attempt to measure their impact and ascertain any potential trajectory from government-level agenda to borough-level contextualisation. Inspired by content analysis, but also taking into account the implementation of the documents, this study draws upon the Every Child Matters green…

  11. 3D Finite Element Study on: Bar Splinted Implants Supporting Partial Denture in the Reconstructed Mandible

    PubMed Central

    El-Anwar, Mohamed; Ghali, Rami; Aboelnagga, Mona

    2016-01-01

    AIM: This study aimed to estimate the stress patterns induced by the masticatory loads on a removable prosthesis supported and retained by bar splinted implants placed in the reconstructed mandible with two different clip materials and without clip, in the fibula-jaw bone and prosthesis using finite element analysis. METHODS: Two 3D finite element models were constructed, that models components were modeled on commercial CAD/CAM software then assembled into finite element package. Vertical loads were applied simulating the masticatory forces unilaterally in the resected site and bilaterally in the central fossa of the lower first molar as 100N (tension and compression). Analysis was based on the assumption full osseointegration between different types of bones, and between implants and fibula while fixing the top surface of the TMJ in place. RESULTS: The metallic bar connecting the three implants is insensitive to the clips material. Its supporting implants showed typical behavior with maximum stress values at the neck region. Fibula and jaw bone showed stresses within physiologic, while clips material effect seems to be very small due to its relatively small size. CONCLUSION: Switching loading force direction from tensile to compression did-not change the stresses and deformations distribution, but reversed their sign from positive to negative. PMID:27275353

  12. A Spatial Hedonic Analysis of the Effects of Wind Energy Facilities on Surrounding Property Values in the United States

    SciTech Connect

    Hoen, Ben; Wiser, Ryan; Cappers, Peter; Brown, Jason P.; Jackson, Thomas; Thayer, Mark A.

    2013-08-21

    This report summarizes a new analysis, building on previously published research, about wind energy’s effects on residential property values. This study helps fill research gaps by collecting and analyzing data from 27 counties across nine U.S. states, related to 67 different wind facilities, and constructs a pooled model that investigates average effects near the turbines across the sample while controlling for local variables, such as sale prices of nearby homes.

  13. In vivo comparison of force development with various materials of implant-supported prostheses.

    PubMed

    Kim, H K; Heo, S J; Koak, J Y; Kim, S K

    2009-08-01

    The purpose of this study was to measure axial loading, generating bending moments on fibre reinforced composite (FRC) implant prostheses using strain-gauged customized abutment in vivo. Bending moments of conventional implant prosthetic material were also measured and the data were compared with those for FRC. Three unit fixed dental prostheses were made for two dental implant fixtures, which had been functioning properly for more than one year using Tescera ATL, porcelain fused to metal and gold as occlusal material. Three patients participated in this study; two patients had two implants on one side of the mandible and one had two implants on both sides of the mandible. Five sets of fixed dental prostheses were fabricated for each material and these were cemented with Temp-bond on strain-gauged customized abutments, which were screwed into the underlying implant fixtures. Axial loadings and bending moments were measured when a patient bit the experimental fixed dental prosthesis. ANOVA and the Tukey HSD test (alpha = 0.05) were used for statistical analysis. There were no significant differences in normalized bending moments among the three different implant prosthetic materials. Within the limitations of this study, Tescera ATL generated bending moments similar to conventional implant prosthetic materials such as gold and porcelain. PMID:19548956

  14. Effect of Luting Agents on Retention of Dental Implant-Supported Prostheses.

    PubMed

    Pan, Yu-Hwa; Lin, Tai-Min; Liu, Perng-Ru; Ramp, Lance C

    2015-10-01

    To evaluate the retentive strength of 7 different luting agents in cement-retained implant abutment/analog assemblies. Fifty-six externally hexed dental implant abutment/analog assemblies and cast superstructures were divided randomly into 7 groups for cementation with each of the 7 luting agents. Five definitive cements tested were zinc phosphate cement, All-Bond 2, Maxcem, RelyX Luting cement, HY-Bond, and two provisional cements, ImProv and Premier. Cast superstructures were cemented onto the implant abutments and exposed to 1000 thermal cycles (0°C-55°C) and 100 000 cycles on a chewing simulator (75 N load). A universal testing machine was used to measure cement failure load of the assembled specimens. Cement failure load was evaluated with 1-way ANOVA and Duncan's multiple range analysis. Significant differences in cement failure loads were measured (P < .0001). Post hoc testing with Duncan's multiple range indicated 4 separate groupings. Maxcem and All-Bond 2 were comparable, having the greatest load failure. RelyX and zinc phosphate cement were analogous, and higher than HY-Bond. Improv and Premier constituted a pair, which demonstrated the lowest retentive values. Within the limitations of this in vitro study, Maxcem and All-Bond 2 are good candidates for cement-retained implant prostheses while concerning retention. PMID:24666355

  15. Retentiveness of various luting agents used with implant-supported prostheses: a preliminary in vitro study.

    PubMed

    Garg, Pooja; Gupta, Gaurav; Prithviraj, D R; Pujari, Malesh

    2013-01-01

    The aim of this preliminary in vitro study was to compare the retentiveness of a luting agent designed for use with dental implants to luting agents designed for use with tooth-retained restorations. The following luting agents were tested: (1) implant cement, (2) resin-bonded zinc oxide-eugenol cement, (3) zinc phosphate cement, (4) zinc polycarboxylate cement, and (5) glass-ionomer cement. After cementation, each sample was subjected to a pull-out test using a universal testing machine, and the loads required to remove the crowns were recorded. The mean values and standard deviations of cement failure loads were analyzed using analysis of variance and the Bonferroni test. The mean cement failure loads (N) were 333.86 ± 18.91 for implant cement, 394.62 ± 9.76 for resin-bonded zinc oxide-eugenol cement, 629.30 ± 20.65 for zinc phosphate cement, 810.08 ± 11.52 for zinc polycarboxylate cement, and 750.17 ± 13.78 for glass-ionomer cement. The retention provided by polycarboxylate cement was significantly greater than that of all other luting agents; the implant cement showed the lowest retention values. These preliminary in vitro observations need to be confirmed under conditions that more closely approximate the clinical environment. PMID:23342339

  16. A mini dental implant-supported obturator application in a patient with partial maxillectomy due to tumor: case report.

    PubMed

    Dilek, Ozkan Cem; Tezulas, Emre; Dincel, Mert

    2007-03-01

    Following a partial maxillectomy in a patient, the oral and nasal cavities remain open, providing a passageway for transmission of air and fluids between the 2 cavities. In such cases the primary aim should be the construction of an implant-supported obturator prosthesis with adequate retention, stability, and peripheral seal. In this case report, a 34-year-old female patient who underwent a class II (according to Okay et al.) partial maxillectomy 14 years before was fitted with an obturator that was supported by 5 mini dental implants. The reason for the preference of mini dental implants is the lack of adequate bone tissue for conventional implant placement in the resected area and the placement of mini dental implants with a simple surgical procedure. The treatment achieved restoration of the lost functions, which satisfied the patient, restoring her self-confidence and enhancing her quality of life. Thus, applying obturators supported by mini dental implants was successful and may be considered as an alternative to more complicated surgical techniques. Although the presented case is promising, further clinical research is needed to draw more definite conclusions. PMID:17197207

  17. The effect of casting and masticatory simulation on strain and misfit of implant-supported metal frameworks.

    PubMed

    Bhering, Cláudia Lopes Brilhante; Marques, Isabella da Silva Vieira; Takahashi, Jessica Mie Ferreira Koyama; Barão, Valentim Adelino Ricardo; Consani, Rafael Leonardo Xediek; Mesquita, Marcelo Ferraz

    2016-05-01

    The influence of casting and masticatory simulation on marginal misfit and strain in multiple implant-supported prostheses was evaluated. Three-unit screw retained fixed dental prosthesis (FDP) and screw retained full-arch fixed dental prosthesis (FAFDP) frameworks were made using calcinable or overcasted cylinders on conical dental implant abutment. Four groups were obtained according to the cylinder and prosthesis type (n=10). Frameworks were casted in CoCr alloy and subjected to strain gauge analyses and marginal misfit measurements before and after 10(6) mechanical cycles (2 Hz/280 N). Results were submitted to ANOVA, Tukey's HSD and Pearson correlation test (α=0.05). No difference was found on misfit among all groups and times (p>0.05). Overcasted frameworks showed higher strain than the calcinable ones (FDP - Initial p=0.0047; Final p=0.0004; FAFDP - Initial p=0.0476; Final p=0.0115). The masticatory simulation did not influence strain (p>0.05). No correlation was observed between strain and misfit (r=0.24; p>0.05). In conclusion, the marginal misfit value in the overcasted full-arch frameworks was higher than clinical acceptable data. It proved that overcasted method is not an ideal method for full-arch prosthesis. Overcasted frameworks generate higher strain upon the system. The masticatory simulation had no influence on misfit and strain of multiple prostheses. PMID:26952480

  18. The selection criteria of temporary or permanent luting agents in implant-supported prostheses: in vitro study

    PubMed Central

    Gonzalez-Gonzalez, Ignacio; Brizuela-Velasco, Aritza; Ellacuria-Echebarria, Joseba

    2016-01-01

    PURPOSE The use of temporary or permanent cements in fixed implant-supported prostheses is under discussion. The objective was to compare the retentiveness of one temporary and two permanent cements after cyclic compressive loading. MATERIALS AND METHODS The working model was five solid abutments screwed to five implant analogs. Thirty Cr-Ni alloy copings were randomized and cemented to the abutments with one temporary (resin urethane-based) or two permanent (resin-modified glass ionomer, resin-composite) cements. The retention strength was measured twice: once after the copings were cemented and again after a compressive cyclic loading of 100 N at 0.72 Hz (100,000 cycles). RESULTS Before loading, the retention strength of resin composite was 75% higher than the resin-modified glass ionomer and 2.5 times higher than resin urethanebased cement. After loading, the retentiveness of the three cements decreased in a non-uniform manner. The greatest percentage of retention loss was shown by the temporary cement and the lowest by the permanent resin composite. However, the two permanent cements consistently show high retention values. CONCLUSION The higher the initial retention of each cement, the lower the percentage of retention loss after compressive cyclic loading. After loading, the resin urethane-based cement was the most favourable cement for retrieving the crowns and resin composite was the most favourable cement to keep them in place. PMID:27141259

  19. Rhetoric, power and legitimacy: a critical analysis of the public policy disputes surrounding stem cell research in Australia (2005-6).

    PubMed

    Lysaght, Tamra; Kerridge, Ian

    2012-02-01

    In December 2006, the Australian Parliament liberalized regulation governing stem cell research. This decision and preceding legislative review generated considerable public debate, which centred on objections to the deliberate creation and destruction of human embryos for research purposes. This paper draws on qualitative research conducted on the public debate surrounding this policy episode. The aim of this research was to examine how science and scientific knowledge are mobilized by participants in these debates to support their arguments. Data were collected from 109 newspaper opinion editorials as well as 23 in-depth interviews and examined using qualitative content and thematic analysis. Results of this analysis depict science as a rhetorical, moral and political resource that provides opportunities for participants to gain legitimacy, negotiate meaning and assert authority in the public domain. The mobilization of science in public discourse is discussed along with suggestions that are aimed at encouraging greater transparency and inclusiveness in public debates around contested science and emergent technologies. PMID:22586845

  20. Analysis of mechanical behavior of implant-supported prostheses in the anterior maxilla: analysis by speckle pattern interferometry

    NASA Astrophysics Data System (ADS)

    Corrêa, Cássia B.; Ramos, Nuno V.; Monteiro, Jaime; Vaz, Luis G.; Vaz, Mario A. P.

    2012-10-01

    The use of implants to rehabilitation of total edentulous, partial edentulous or single tooth is increasing, it is due to the high rate of success that this type of treatment present. The objective of this study was to analyze the mechanical behavior of different positions of two dental implants in a rehabilitation of 4 teeth in the region of maxilla anterior. The groups studied were divided according the positioning of the implants. The Group 1: Internal Hexagonal implant in position of lateral incisors and pontic in region of central incisors; Group 2: Internal Hexagonal implant in position of central incisors and cantilever of the lateral incisors and Group3 - : Internal Hexagonal implants alternate with suspended elements. The Electronic Speckle Pattern Interferometry (ESPI) technique was selected for the mechanical evaluation of the 3 groups performance. The results are shown in interferometric phase maps representing the displacement field of the prosthetic structure.

  1. Remote sensing and GIS-based integrated analysis of land cover change in Duzce plain and its surroundings (north western Turkey).

    PubMed

    Ikiel, Cercis; Ustaoglu, Beyza; Dutucu, Ayse Atalay; Kilic, Derya Evrim

    2013-02-01

    The aim of this study is to research natural land cover change caused by the permanent effects of human activities in Duzce plain and its surroundings, and to determine the current status of the land cover. For this purpose, two Landsat TM images were used in the study for the years 1987 and 2010. These images are analysed by using data image processing techniques in ERDAS Imagine©10.0 and ArcGIS©10.0 software. Land cover change nomenclature is classified according to the Coordination of Information on the Environment Level 2 Classification (1--urban fabric, 2--industrial, commercial and transport units, 3--heterogeneous agricultural areas, 4--forests, and 5--inland wetlands). Furthermore, the image analysis results are confirmed by the field research. According to the results, a decrease of 33.5 % was recorded in forest areas from 24,840.7 to 16,529.0 ha; an increase of 11.2 % was recorded in heterogeneous agricultural areas from 47,702.7 to 53,051.7 ha. Natural vegetation, which is the large part of land cover in the research area, has been changing rapidly because of rapid urbanisation and agricultural activities. As a result, it is concluded that significant changes have occurred on the natural land cover between the years 1987 and 2010 in the Duzce plain and its surroundings. PMID:22585402

  2. Influence of Sealing of the Screw Access Hole on the Fracture Resistance of Implant-Supported Restorations.

    PubMed

    Pereira, Rodrigo de Paula; Rocha, Cibele Oliveira de Melo; Reis, José Maurício dos Santos Nunes; Arioli-Filho, João Neudenir

    2016-01-01

    The purpose of this study was to assess the influence of sealing of the screw access hole (SAH) on the fracture resistance of metal-ceramic implant-supported restorations. UCLA abutments were used to make 30 implant-retained mandibular molar restorations and divide equally into three groups: Group SRS: screw-retained restorations with SAH sealed; Group SRNS: screw-retained restorations with SAH not sealed; Group CR: cement-retained restorations. The following protocol was adopted to restore the SAH: the ceramic surface of the SAH was air-abraded with aluminum oxide; etched with 10% hydrofluoric acid; a silane coupling agent and a bonding agent were applied; cotton pellets were used as filling material and P-60 resin composite as restoring material. The cement-retained restorations were cemented with Rely-X U100. A metal rod with a spherical tip of 6.0 mm diameter was used to apply a vertical static load, simultaneously on the buccal and lingual incline cusps, at a crosshead speed of 0.5 mm/min until the fracture of the specimens. Data were analyzed using one-way ANOVA and Dunnet test (p<0.05) for multiples comparisons. The mode of failure was evaluated by a scanning electron microscopy (SEM). No significant difference between screw-retained restorations was found. The highest mean fracture resistance values were observed with CR group. Therefore, it was shown that SAH sealing did not influence the fracture resistance of the screw-retained restorations. PMID:27058376

  3. Clinical and radiographic evaluation of periodontal and peri-implant conditions in patients with implant-supported prosthesis.

    PubMed

    Abreu, Monica H; Bianchini, Marco A; Magini, Ricardo S; Rösing, Cassiano K

    2007-01-01

    The aim of the present study was to clinically and radiographically assess the peri-implant and periodontal conditions in partially edentulous patients with implant-supported fixtures installed, at least, one year prior to the study. 41 patients were examined by a calibrated examiner in relation to the following implant-associated parameters: Modified Plaque Index (mPlI), Modified Bleeding Index (mBI), probing depth (PD), clinical attachment level (CAL) and bleeding on probing of the bottom of the crevice (BOP). Also, the remaining teeth were assessed in terms of Plaque Index (PlI), Gingival Index (GI), PD, CAL and BOP. The peri-implant bone loss was evaluated by means of periapical radiographs. Measurements of pre-operatory and final bone levels allowed an estimation of bone loss associated to teeth and a comparison with bone loss around implants. None of the individuals presented late loss of implants until the examination took place. No statistically significant differences were observed between PlI (0.90+/-0.07) and mPlI (0.82+/-0.13), or between GI (0.11+/-0.02) and mBI (0.10+/-0.02). However, PD, CAL and BOP values were higher in implants than in teeth (Wald Test, p<0.01). Implants presented a mean annual bone loss during the study period of 0.77 mm (SE=0.06). Teeth virtually did not present any bone loss (mean value of 0.36%) whereas implants exhibited a bone loss value of 17.11%. Plaque accumulation and marginal inflammation did not differ between teeth and implants. However, subgingival inflammation was higher in implants than in teeth. The destruction measurements suggest greater losses in implants, as expected because of tissue remodelation. PMID:18590257

  4. Effect of tightening torque on the marginal adaptation of cement-retained implant-supported fixed dental prostheses

    PubMed Central

    Ghanbarzadeh, Jalil; Dashti, Hossin; Karamad, Reza; Alikhasi, Marzieh; Nakhaei, Mohammadreza

    2015-01-01

    Background: The final position of the abutment changes with the amount of tightening torque. This could eventually lead to loss of passivity and marginal misfit of prostheses. The aim of this study was to evaluate the effect of three different tightening torques on the marginal adaptation of 3-unit cement-retained implant-supported fixed dental prostheses (FDPs). Materials and Methods: Two implants (Straumann) were inserted in an acrylic block so that one of the implants was placed vertically and the other at a 15° vertical angle. A straight abutment and a 15° angulated abutment were connected to the vertically and obliquely installed implants, respectively, so that the two abutments were parallel. Then, 10 cement-retained FDPs were waxed and cast. Abutments were tightened with 10, 20, and 35 Ncm torques, respectively. Following each tightening torque, FDPs were luted on respective abutments with temporary cement. The marginal adaptation of the retainers was evaluated using stereomicroscope. FDPs were then removed from the abutments and were sectioned at the connector sites. The retainers were luted again on their respective abutments. Luting procedures and marginal adaptation measurement were repeated. Data were analyzed by ANOVA and least significant difference tests (α = 0.05). After cutting the FDP connectors, the independent samples t-test was used to compare misfit values (α = 0.05). Results: Following 10, 20, and 35 Ncm tightening torques, the marginal discrepancy of the retainers of FDPs significantly increased (P < 0.05). There was no significant difference between the marginal discrepancies of these two retainers (P > 0.05). The marginal gap values of angulated abutment retainers (ANRs) were significantly higher than those of the straight abutment after cutting the connectors (P = 0.026). Conclusion: Within the limitations of this study, the marginal misfit of cement-retained FDPs increased continuously when the tightening torque increased. After

  5. The Effects of New Design of Access Hole on Porcelain Fracture Resistance of Implant-Supported Crowns

    PubMed Central

    Derafshi, Reza; Farzin, Mitra; Taghva, Masoumeh; Heidary, Hossein; Atashkar, Berivan

    2015-01-01

    Statement of the Problem One disadvantage of cement-retained crowns is the lack of predictable irretrievability. This problem can be overcome through designing a screw access hole in the metal substructure of cement-retained restoration and using porcelain stain to define this area. Purpose This study aimed to evaluate the influence of existence of screw access hole on porcelain fracture resistance of metal-ceramic implant-supported crowns. Materials and Method Thirty six standardized metal-ceramic crowns were fabricated and divided into 3 groups (n=12); group 1 conventional cement-retained metal-ceramic crowns as control group, group 2 cement-retained MC crowns in which porcelain stain was used to define the location of screw access channel, and group 3 cement-retained metal-ceramic crowns in the metal substructure of which a hole and ledge was designed in the location of screw access channel. The specimens were cemented (TempBond, Kerr) to their dedicated abutments. A hole was made in the location of screw access channel in group 2 and 3 and filled with photo-polymerized composite resin (3M; ESPE). All specimens were thermocycled and loaded in universal testing machine at crosshead speed of 2mm/min until fracture. Mean values of load at fracture were calculated in each group and compared with One-way ANOVA (α=0.05). Results Mean value of the load required to fracture the restorations was 1947±487 N in group 1, 1927±539 N in group 2, and 2170±738 N in group 3. No statistically significant difference was found between the fracture resistance values of the three groups (p> 0.05) Conclusion Presence of screw access channel in cement-retained implant restorations does not compromise fracture resistance. PMID:26106637

  6. Parsing surrounding space into regions.

    PubMed

    Franklin, N; Henkel, L A; Zangas, T

    1995-07-01

    Surrounding space is not inherently organized, but we tend to treat it as though it consisted of regions (e.g., front, back, right, and left). The current studies show that these conceptual regions have characteristics that reflect our typical interactions with space. Three experiments examined the relative sizes and resolutions of front, back, left, and right around oneself. Front, argued to be the most important horizontal region, was found to be (a) largest, (b) recalled with the greatest precision, and (c) described with the greatest degree pf detao. Our findings suggest that some of the characteristics of the category model proposed by Huttenlocher, Hedges, and Duncan (1991) regarding memory for pictured circular displays may be generalized to space around oneself. More broadly, our results support and extend the spatial framework analysis of representation of surrounding space (Franklin & Tversky, 1990). PMID:7666754

  7. The influence of interproximal contact on implant-supported fixed partial dentures in the posterior jaw: a photoelastic analysis.

    PubMed

    Naves, Marina Melo; de Menezes, Helder Henrique Machado; de Magalhães, Denildo; de Araújo, Cleudmar Amaral; Júnior, Paulo Cézar Simamoto

    2015-02-01

    The aim of this study was to analyze the effect of the separation of prosthetic crowns from fixed partial dentures by means of stress gradient evaluation. Three photoelastic models were created to examine contiguous implants with varying contact between the crowns (contact point [CP], contact surface [CS], splinted [SP]). The SP group presented the best results, followed by the CS group, indicating that the use of splinted prosthetic crowns and crowns with broad surface contacts is viable when considering the stress values. PMID:23397888

  8. Assessment of the impact of petroleum and petrochemical industries to the surrounding areas in Malaysia using mosses as bioindicator supported by multivariate analysis.

    PubMed

    Abdullah, Mohd Zahari Bin; Saat, Ahmad Bin; Hamzah, Zaini Bin

    2012-06-01

    Biomonitoring of multi-element atmospheric deposition using terrestrial moss is a well-established technique in Europe. Although the technique is widely known, there were very limited records of using this technique to study atmospheric air pollution in Malaysia. In this present study, the deposition of 11 trace metals surrounding the main petroleum refinery plant in Kerteh Terengganu (eastern part of peninsular Malaysia) has been evaluated using two local moss species, namely Hypnum plumaeforme and Taxithelium instratum as bioindicators. The study was also done by means of observing whether these metals are attributed to work related to oil exploration in this area. The moss samples have been collected at 30 sampling stations in the vicinity of the petrochemical industrial area covering up to 15 km to the south, north, and west in radius. The contents of heavy metal in moss samples were analyzed by energy dispersive x-ray fluorescence technique. Distribution of heavy metal content in all mosses is portrayed using Surfer software. Areas of the highest level of contaminations are highlighted. The results obtained using the principal components analysis revealed that the elements can be grouped into three different components that indirectly reflected three different sources namely anthropogenic factor, vegetation factor, and natural sources (soil dust or substrate) factor. Heavy metals deposited mostly in the distance after 9 km onward to the western part (the average direction of wind blow). V, Cr, Cu, and Hg are believed to have originated from local petrochemical-based industries operated around petroleum industrial area. PMID:21822578

  9. FIREPLACE SURROUND. THIS SURROUND WAS FOUND IN THE NORTHEAST BED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FIREPLACE SURROUND. THIS SURROUND WAS FOUND IN THE NORTHEAST BED CHAMBER IN THREE PIECES. ITS DELICATE ADAMESQUE DETAILING—IN KEEPING WITH THE DRAWING ROOM AND DINING ROOM DOOR ARCHITRAVES—AND THE PRESENCE OF LATER FIREPLACE SURROUNDS IN THESE ROOMS INDICATE THAT IT PROBABLY WAS ONCE INSTALLED IN ONE OF THE TWO PUBLIC SPACES - The Woodlands, 4000 Woodlands Avenue, Philadelphia, Philadelphia County, PA

  10. An in vitro investigation into retention strength and fatigue resistance of various designs of tooth/implant supported overdentures.

    PubMed

    Fatalla, Abdalbseet A; Song, Ke; Du, Tianfeng; Cao, Yingguang

    2012-02-01

    and 2880 insertion and removal cycles. During the tensile test a cross-head speed of 10 mm/min was applied. Values of absolute force (AF) and relative force (RF) were statistically analyzed by two-way ANOVA and multiple comparison Tukey's tests between groups and cycles periods. The results of fatigue tests showed a 50% reduction in retention force in the subgroups with flexible attachments. A triangular design of overdenture support foundations with O-Ring attachments revealed the lowest value of AF and a relatively high reduction in RF. The four overdenture support designs with flexible acrylic attachments improved the retention force and reduced the fatigue retention. Furthermore, the results of the investigation demonstrate that flexible acrylic attachments for both teeth and implant-supported overdentures offer a wide range of retention forces. PMID:22282258

  11. Modified section method for laser-welding of ill-fitting cp Ti and Ni-Cr alloy one-piece cast implant-supported frameworks.

    PubMed

    Tiossi, R; Falcão-Filho, H; Aguiar Júnior, F A; Rodrigues, R C; Mattos, M da G; Ribeiro, R F

    2010-05-01

    This study aimed to verify the effect of modified section method and laser-welding on the accuracy of fit of ill-fitting commercially pure titanium (cp Ti) and Ni-Cr alloy one-piece cast frameworks. Two sets of similar implant-supported frameworks were constructed. Both groups of six 3-unit implant-supported fixed partial dentures were cast as one-piece [I: Ni-Cr (control) and II: cp Ti] and evaluated for passive fitting in an optical microscope with both screws tightened and with only one screw tightened. All frameworks were then sectioned in the diagonal axis at the pontic region (III: Ni-Cr and IV: cp Ti). Sectioned frameworks were positioned in the matrix (10-Ncm torque) and laser-welded. Passive fitting was evaluated for the second time. Data were submitted to anova and Tukey-Kramer honestly significant difference tests (P < 0.05). With both screws tightened, one-piece cp Ti group II showed significantly higher misfit values (27.57 +/- 5.06 microm) than other groups (I: 11.19 +/- 2.54 microm, III: 12.88 +/- 2.93 microm, IV: 13.77 +/- 1.51 microm) (P < 0.05). In the single-screw-tightened test, with readings on the opposite side to the tightened side, Ni-Cr cast as one-piece (I: 58.66 +/- 14.30 microm) was significantly different from cp Ti group after diagonal section (IV: 27.51 +/- 8.28 microm) (P < 0.05). On the tightened side, no significant differences were found between groups (P > 0.05). Results showed that diagonally sectioning ill-fitting cp Ti frameworks lowers misfit levels of prosthetic implant-supported frameworks and also improves passivity levels of the same frameworks when compared to one-piece cast structures. PMID:20149062

  12. A 4-year follow-up of two complete mandibular implant-supported removable prostheses in a patient with severe rheumatoid polyarthritis: case report.

    PubMed

    Ella, Bruno; Lasserre, Jean-François; Blanchard, Jean-Pierre; Fricain, Jean Christophe

    2011-01-01

    Rheumatoid polyarthritis is a systemic autoimmune disease characterized by chronic synovitis and bone damage associated with significant functional disability and morbidity. This case report describes a 4-year follow-up of a 56-year-old female receiving polymedication for severe rheumatoid polyarthritis and osteoporosis with a fully edentulous maxilla treated with two osseointegrated implants supporting a removable mandibular prosthesis. No practitioner wanted to use implants to stabilize her mandibular prosthesis because of the health risks involved. This report encourages the dental practitioner to be familiar with the symptoms and oral manifestations of rheumatoid polyarthritis in order to help manage this disease when patients lose all of their teeth. PMID:21483874

  13. Technique for fabricating a custom gingival mask using a maxillary complete-arch implant-supported fixed interim prosthesis with an integrated verification cast.

    PubMed

    Esguerra, Roxanna J

    2016-01-01

    The custom gingival mask technique duplicates the tissue contours created by an implant-supported fixed interim prosthesis, which has been verified for satisfactory esthetics, phonetics, hygiene access, and patient comfort. This allows the dental laboratory technician to accurately duplicate the contours of the interim prosthesis in the definitive prosthesis. The technique described also incorporates a cast verification step to ensure the accurate, passive fit of the definitive prosthesis while eliminating the duplicate impression copings and implant replicas typically required for a verification cast. PMID:26384534

  14. Bioinformatic and phylogenetic analysis of the CLAVATA3/EMBRYO-SURROUNDING REGION (CLE) and the CLE-LIKE signal peptide genes in the Pinophyta

    PubMed Central

    2014-01-01

    Background There is a rapidly growing awareness that plant peptide signalling molecules are numerous and varied and they are known to play fundamental roles in angiosperm plant growth and development. Two closely related peptide signalling molecule families are the CLAVATA3-EMBRYO-SURROUNDING REGION (CLE) and CLE-LIKE (CLEL) genes, which encode precursors of secreted peptide ligands that have roles in meristem maintenance and root gravitropism. Progress in peptide signalling molecule research in gymnosperms has lagged behind that of angiosperms. We therefore sought to identify CLE and CLEL genes in gymnosperms and conduct a comparative analysis of these gene families with angiosperms. Results We undertook a meta-analysis of the GenBank/EMBL/DDBJ gymnosperm EST database and the Picea abies and P. glauca genomes and identified 93 putative CLE genes and 11 CLEL genes among eight Pinophyta species, in the genera Cryptomeria, Pinus and Picea. The predicted conifer CLE and CLEL protein sequences had close phylogenetic relationships with their homologues in Arabidopsis. Notably, perfect conservation of the active CLE dodecapeptide in presumed orthologues of the Arabidopsis CLE41/44-TRACHEARY ELEMENT DIFFERENTIATION (TDIF) protein, an inhibitor of tracheary element (xylem) differentiation, was seen in all eight conifer species. We cloned the Pinus radiata CLE41/44-TDIF orthologues. These genes were preferentially expressed in phloem in planta as expected, but unexpectedly, also in differentiating tracheary element (TE) cultures. Surprisingly, transcript abundances of these TE differentiation-inhibitors sharply increased during early TE differentiation, suggesting that some cells differentiate into phloem cells in addition to TEs in these cultures. Applied CLE13 and CLE41/44 peptides inhibited root elongation in Pinus radiata seedlings. We show evidence that two CLEL genes are alternatively spliced via 3′-terminal acceptor exons encoding separate CLEL peptides

  15. Effect of cantilever length and alloy framework on the stress distribution in peri-implant area of cantilevered implant-supported fixed partial dentures.

    PubMed

    Suedam, Valdey; Moretti Neto, Rafael Tobias; Sousa, Edson Antonio Capello; Rubo, José Henrique

    2016-04-01

    Because many mechanical variables are present in the oral cavity, the proper load transfer between the prosthesis and the bone is important for treatment planning and for the longevity of the implant-supported fixed partial denture. Objectives To verify the stress generated on the peri-implant area of cantilevered implant-supported fixed partial dentures and the potential effects of such variable. Material and Methods A U-shaped polyurethane model simulating the mandibular bone containing two implants (Ø 3.75 mm) was used. Six groups were formed according to the alloy's framework (CoCr or PdAg) and the point of load application (5 mm, 10 mm and 15 mm of cantilever arm). A 300 N load was applied in pre-determined reference points. The tension generated on the mesial, lingual, distal and buccal sides of the peri-implant regions was assessed using strain gauges. Results Two-way ANOVA and Tukey statistical tests were applied showing significant differences (p<0.05) between the groups. Pearson correlation test (p<0.05) was applied showing positive correlations between the increase of the cantilever arm and the deformation of the peri-implant area. Conclusions This report demonstrated the CoCr alloy shows larger compression values compared to the PdAg alloy for the same distances of cantilever. The point of load application influences the deformation on the peri-implant area, increasing in accordance with the increase of the lever arm. PMID:27119758

  16. The Ability of Dental Specialists to Distinguish Lateral Incisor Metal-Free From Porcelain-Fused-to-Metal Implant Supported Crowns.

    PubMed

    De Melo, Eduardo V; Kauling, Ana Elisa C; Freitas, Sérgio Fernando T; Cardoso, Antônio C; Ferreira, Cimara Fortes

    2014-12-01

    The objective of this study was to evaluate the ability of dental specialists to distinguish lateral incisor metal-free from porcelain-fused-to-metal implant supported crowns in the anterior region. Five single-tooth implants in the maxillary lateral incisor region were restored with two types of implant-supported crowns (porcelain-fused-to-metal and metal-free). Photographs were presented to 20 evaluators. The evaluators had to answer whether the crown was: metal-free, porcelain-fused-to-metal or they could not tell the difference. The results showed that groups 1 (all participants), 3 (Restorative & Prosthodontic specialists), 4 (graduated 10 years) and 5 (graduated > 10 years) failed to respond correctly (P > 0.05) to which type of crown was presented to them. Group 2 (Periodontology & Implantology specialists) showed an accuracy rate of 35.6% (P = 0.009), in relation to metal-free crowns, 5.6 which is below the random index. The authors concluded that the evaluators from the 5 groups studied were unable to significantly distinguish which type of crown was used in the 10 presented situations. PMID:26466439

  17. Effects of Mucosal Thickness on the Stress Distribution and Denture Stability of Mandibular Implant-Supported Overdentures with Unsplinted Attachments In Vitro

    PubMed Central

    Haruta, Asuka; Matsushita, Yasuyuki; Tsukiyama, Yoshihiro; Sawae, Yoshinori; Sakai, Nobuo; Koyano, Kiyoshi

    2011-01-01

    The aim of this study was to compare the effects of mucosal thickness on the stress pattern around implants and movement of implant-supported overdentures with ball/female and three different types of magnetic attachments. After insertion of two root-form implants into a mandibular model, the surface of the model was covered with a 1.5- or 3-mm layer of impression material to simulate the oral mucosa, and removable overdentures were fabricated on each model. A 50-N vertical force was applied to the right first molar, and the resultant stress distribution and denture movement were measured. In the 1.5-mm mucosal model, the magnetic attachments showed significantly lower bending moments than did the ball attachment. The denture base displacement was the lowest on a magnetic attachment. In this study, use of magnetic attachments could be advantageous for mandibular implant-supported overdentures based on lower stress and better denture stability especially in the thin mucosal model. PMID:21799705

  18. Implant-supported overdenture manufactured using CAD/CAM techniques to achieve horizontal path insertion between the primary and secondary structure: A clinical case report

    PubMed Central

    Agustín-Panadero, Rubén; Peñarrocha-Oltra, David; Gomar-Vercher, Sonia; Ferreiroa, Alberto

    2015-01-01

    This report describes the case of an edentulous patient with an atrophic maxilla and severe class III malocclusion. Prosthetic rehabilitation was performed using CAD/CAM techniques for manufacturing an implant-supported overdenture with horizontal insertion. A vestibulo-lingual insertion overdenture is a precision prosthesis with a fixation system affording a good fit between the primary and secondary structure. Both structures exhibit passive horizontal adjustment. This treatment option requires the same number of implants as implant-supported fixed dentures. The horizontal assembly system prevents the prosthesis from loosening or moving in response to axial and non-axial forces. The technique was used to rehabilitate a patient presenting an atrophic upper maxilla, with the insertion of 8 implants. No complications were reported at follow-up 3, 6 and 12 months after fitting of the prosthesis. This system offers solutions to the clinical and laboratory complications associated with hybrid prostheses, concealing emergence of the chimneys and improving implant-prosthesis hygiene. PMID:26140179

  19. Surface shapes and surrounding environment analysis of single- and double-stranded DNA-binding proteins in protein-DNA interface.

    PubMed

    Wang, Wei; Liu, Juan; Sun, Lin

    2016-07-01

    Protein-DNA bindings are critical to many biological processes. However, the structural mechanisms underlying these interactions are not fully understood. Here, we analyzed the residues shape (peak, flat, or valley) and the surrounding environment of double-stranded DNA-binding proteins (DSBs) and single-stranded DNA-binding proteins (SSBs) in protein-DNA interfaces. In the results, we found that the interface shapes, hydrogen bonds, and the surrounding environment present significant differences between the two kinds of proteins. Built on the investigation results, we constructed a random forest (RF) classifier to distinguish DSBs and SSBs with satisfying performance. In conclusion, we present a novel methodology to characterize protein interfaces, which will deepen our understanding of the specificity of proteins binding to ssDNA (single-stranded DNA) or dsDNA (double-stranded DNA). Proteins 2016; 84:979-989. © 2016 Wiley Periodicals, Inc. PMID:27038080

  20. Local surrounding of vanadium atoms in CuCr1 - x V x S2: X-ray absorption spectroscopy analysis

    NASA Astrophysics Data System (ADS)

    Smirnova, Yu. O.; Smolentsev, N. Yu.; Guda, A. A.; Soldatov, M. A.; Kvashnina, K. O.; Glatzel, P.; Korotaev, E. V.; Soldatov, A. V.; Mazalov, L. N.

    2013-03-01

    In the present work local surrounding of vanadium atoms in layered copper-chromium disulfides CuCr1 - x V x S2 is investigated using high-resolution X-ray absorption spectroscopy above vanadium K-edge. Based on experimental and theoretically simulated spectra comparison it is shown that vanadium atoms replace chromium ones even at high concentrations of vanadium and that they are in 3+ oxidation state.

  1. Vertical misfit of laser-sintered and vacuum-cast implant-supported crown copings luted with definitive and temporary luting agents

    PubMed Central

    Sánchez-Turrión, Andrés; López-Lozano, José F.; Albaladejo, Alberto; Torres-Lagares, Daniel; Montero, Javier; Suárez-García, Maria J.

    2012-01-01

    Objectives. This study aimed to evaluate the vertical discrepancy of implant-supported crown structures constructed with vacuum-casting and Direct Metal Laser Sintering (DMLS) technologies, and luted with different cement types. Study Design. Crown copings were fabricated using: (1) direct metal laser sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC); and (3) vacuum-cast Ti (CT). Frameworks were luted onto machined implant abutments under constant seating pressure. Each alloy group was randomly divided into 5 subgroups (n = 10 each) according to the cement system utilized: Subgroup 1 (KC) used resin-modified glass-ionomer Ketac Cem Plus; Subgroup 2 (PF) used Panavia F 2.0 dual-cure resin cement; Subgroup 3 (RXU) used RelyX Unicem 2 Automix self-adhesive dual-cure resin cement; Subgroup 4 (PIC) used acrylic/urethane-based temporary Premier Implant Cement; and Subgroup 5 (DT) used acrylic/urethane-based temporary DentoTemp cement. Vertical misfit was measured by scanning electron microscopy (SEM). Two-way ANOVA and Student-Newman-Keuls tests were run to investigate the effect of alloy/fabrication technique, and cement type on vertical misfit. The statistical significance was set at α = 0.05. Results. The alloy/manufacturing technique and the luting cement affected the vertical discrepancy (p < 0.001). For each cement type, LS samples exhibited the best fit (p < 0.01) whereas CC and CT frames were statistically similar. Within each alloy group, PF and RXU provided comparably greater discrepancies than KC, PIC, and DT, which showed no differences. Conclusions. Laser sintering may be an alternative to vacuum-casting of base metals to obtain passive-fitting implant-supported crown copings. The best marginal adaptation corresponded to laser sintered structures luted with glass-ionomer KC, or temporary PIC or DT cements. The highest discrepancies were recorded for Co-Cr and Ti cast frameworks bonded with PF or RXU resinous agents. All groups were within the clinically

  2. Complete mouth reconstruction with implant-supported fixed partial dental prostheses fabricated with zirconia frameworks: a 4-year clinical follow-up.

    PubMed

    Puri, Shweta; Parciak, Ewa C; Kattadiyil, Mathew T

    2014-09-01

    Few scientific reports regarding the success of complete mouth partial fixed dental prostheses frameworks fabricated with zirconia are available, especially when dental implants serve as the abutments. A complete mouth reconstruction with zirconia frameworks veneered with feldspathic porcelain is reported involving a 65-year-old white woman who presented with partial edentulism and an unrestorable remaining dentition. After examination, 14 implants were planned (8 in the maxillary arch and 6 in the mandibular arch), and implant-supported zirconia framework screw-retained partial fixed dental prostheses (ISZPFDPs) were fabricated and made in sections for easier retrievability and management. No major complications were encountered during follow-up appointments at 6-month intervals for 4 years. However, minor fractures of the veneering ceramic were noted 4 years after placement. The ISZPFDPs were well accepted by the patient and had a favorable outcome in terms of patient acceptability and success, despite some complications. PMID:24674806

  3. The Evolution and Fabrication of Implant-supported Full-arch Hybrid Prostheses. From Conventional Casted Metal to an All-Ceramic Zirconia.

    PubMed

    Ouzer, Amanda

    2015-11-01

    Implant-supported, full-arch hybrid prostheses have developed from cast-metal frameworks with acrylic or porcelain to all-ceramic zirconia frameworks. CAD/CAM manufacturing removed the inaccuracies seen with casting and made use of zirconia possible. The materials and processes for prosthodontic fabrication are explained. Zirconia is highly opaque and versatile. However, porcelain-veneered zirconia frameworks have shown higher enamel wear, among other problems. Lithium disilicate has been shown to be more translucent than zirconia. Improved stained and more translucent zirconia frameworks have been produced as well. These promising new methods have gained popularity, but long-term studies are scarce and, thus, more research is required. PMID:26749784

  4. Fabricating a tooth- and implant-supported maxillary obturator for a patient after maxillectomy with computer-guided surgery and CAD/CAM technology: A clinical report.

    PubMed

    Noh, Kwantae; Pae, Ahran; Lee, Jung-Woo; Kwon, Yong-Dae

    2016-05-01

    An obturator prosthesis with insufficient retention and support may be improved with implant placement. However, implant surgery in patients after maxillary tumor resection can be complicated because of limited visibility and anatomic complexity. Therefore, computer-guided surgery can be advantageous even for experienced surgeons. In this clinical report, the use of computer-guided surgery is described for implant placement using a bone-supported surgical template for a patient with maxillary defects. The prosthetic procedure was facilitated and simplified by using computer-aided design/computer-aided manufacture (CAD/CAM) technology. Oral function and phonetics were restored using a tooth- and implant-supported obturator prosthesis. No clinical symptoms and no radiographic signs of significant bone loss around the implants were found at a 3-year follow-up. The treatment approach presented here can be a viable option for patients with insufficient remaining zygomatic bone after a hemimaxillectomy. PMID:26774316

  5. Comparison of The Effect of Implant Abutment Surface Modifications on Retention of Implant-Supported Restoration with A Polymer Based Cement

    PubMed Central

    Sahu, Nabaprakash; Lakshmi, Namratha; Azhagarasan, N.S.; Agnihotri, Yoshaskam; Rajan, Manoj; Hariharan, Ramasubramanian

    2014-01-01

    Background: In cement-retained implant-supported restoration it is important to gain adequate retention of definitive restoration as well as retrievability of prosthesis. The surface of the abutment, alloy of the restoration and the type of cement used influences the retention of the restoration. There is a need to analyze the influence of surface modifications of abutments on the retentive capabilities of provisional implant cements. Purpose of study: To compare the effect of implant abutment surface modifications on retention of implant-supported restoration cemented with polymer based cement. Materials and method: Thirty solid titanium implant abutments (ADIN), 8mm height, were divided into 3 groups. Ten abutments with retentive grooves (Group I) as supplied by the manufacturer, Ten abutments milled to 20 taper circumferentially (Group II), and Ten abutments milled and air-abraded with 110 μm aluminum oxide (Group III) were used in this study. Ni-Cr coping were casted for each abutment and polymer based cement was used to secure them to the respective abutments. Using a universal testing machine at a crosshead speed of 0.5 cm/minute, tensile bond strength was recorded (N). Results: Mean tensile bond strength of Group I, II and III were found to be 408.3, 159.9 and 743.8 Newton respectively. The values were statistically different from each other (p<0.001). Conclusion: Abutments with milled and sandblasted surface provide the highest retention followed by abutments with retentive grooves and then by abutments with milled surface when cast copings were cemented to implant abutments with polymer based cement. Clinical implications: Retention of restoration depends on the surface of the abutment as well as the luting agents used. Incorporation of retentive grooves or particle abrasion can enhance retention especially in situation of short clinical crown. PMID:24596785

  6. Effect of cantilever length and alloy framework on the stress distribution in peri-implant area of cantilevered implant-supported fixed partial dentures

    PubMed Central

    SUEDAM, Valdey; MORETTI, Rafael Tobias; SOUSA, Edson Antonio Capello; RUBO, José Henrique

    2016-01-01

    ABSTRACT Because many mechanical variables are present in the oral cavity, the proper load transfer between the prosthesis and the bone is important for treatment planning and for the longevity of the implant-supported fixed partial denture. Objectives To verify the stress generated on the peri-implant area of cantilevered implant-supported fixed partial dentures and the potential effects of such variable. Material and Methods A U-shaped polyurethane model simulating the mandibular bone containing two implants (Ø 3.75 mm) was used. Six groups were formed according to the alloy’s framework (CoCr or PdAg) and the point of load application (5 mm, 10 mm and 15 mm of cantilever arm). A 300 N load was applied in pre-determined reference points. The tension generated on the mesial, lingual, distal and buccal sides of the peri-implant regions was assessed using strain gauges. Results Two-way ANOVA and Tukey statistical tests were applied showing significant differences (p<0.05) between the groups. Pearson correlation test (p<0.05) was applied showing positive correlations between the increase of the cantilever arm and the deformation of the peri-implant area. Conclusions This report demonstrated the CoCr alloy shows larger compression values compared to the PdAg alloy for the same distances of cantilever. The point of load application influences the deformation on the peri-implant area, increasing in accordance with the increase of the lever arm. PMID:27119758

  7. Educational Success and Surrounding Culture

    ERIC Educational Resources Information Center

    Walters, Garrison

    2016-01-01

    The curriculum, instruction, and services we provide in schools, colleges, and universities matter a lot, but if we continue to ignore our students' "surrounding culture," progress toward a more educated nation will continue to be disappointing.

  8. Development of patient-based questionnaire about aesthetic and functional differences between overdentures implant-supported and overdentures tooth-supported. Study of 43 patients with a follow up of 1 year

    PubMed Central

    GARGARI, M.; PRETE, V.; PUJIA, M.; CERUSO, F. M.

    2013-01-01

    SUMMARY Development of patient-based questionnaire about aesthetic and functional differences between overdentures implant-supported and overdentures tooth-supported. Study of 43 patients with a follow up of 1 year. Objective The aim of this study is to compare functional efficiency and patients satisfaction between tooth-supported and implant-supported overdenture through a questionnaire that accurately reflects the real concerns of patients with dental prosthesis. Methods Forty-three patients were selected from the out patient clinic, Department of Dentistry “Fra G.B. Orsenigo Ospedale San Pietro F.B.F.”, Rome, Italy. Their age were ranging from 61 to 83 years. Eighteen patients were rehabilitated with overdentures supported by natural teeth and twenty-five with overdentures implant-supported. Discussion and Result The questionnaire proposed one year after the insertion of the prosthetis has showed that there isn’t difference statistically significant in terms of function, phonetics and aesthetics between overdenture implant-supported and tooth-supported. Conclusions The results of the questionnaire showed that the patients generally had a high level of satisfaction concern to the masticatory function, esthetics and phonetics. In addition, on average, they haven’t difficulty in removal and insertion of the denture and in oral hygiene. They haven’t in both groups problems related to fractures. PMID:23741602

  9. Prosthetic rehabilitation with an implant-supported fixed prosthesis using computer-aided design and computer-aided manufacturing dental technology for a patient with a mandibulectomy: A clinical report.

    PubMed

    Yoon, Hyung-In; Han, Jung-Suk

    2016-02-01

    The fabrication of dental prostheses with computer-aided design and computer-aided manufacturing shows acceptable marginal fits and favorable treatment outcomes. This clinical report describes the management of a patient who had undergone a mandibulectomy and received an implant-supported fixed prosthesis by using additive manufacturing for the framework and subtractive manufacturing for the monolithic zirconia restorations. PMID:26518985

  10. IN VITRO EVALUATION OF THE PRECISION OF WORKING CASTS FOR IMPLANT-SUPPORTED RESTORATION WITH MULTIPLE ABUTMENTS

    PubMed Central

    Castilho, Anderson Almeida; Kojima, Alberto Noriyuki; Pereira, Sarina Maciel Braga; de Vasconcellos, Diego Klee; Itinoche, Marcos Koiti; Faria, Renata; Bottino, Marco Antonio

    2007-01-01

    Objective: The purpose of this study was to compare the accuracy of two working cast fabrication techniques using strain- gauge analysis. Methods: Two working cast fabrication methods were evaluated. Based on a master model, 20 working casts were fabricated by means of an indirect impression technique using polyether after splinting the square transfer copings with acrylic resin. Specimens were assigned to 2 groups (n=10): Group A (GA): type IV dental stone was poured around the abutment analogs in the conventional way; Group B (GB), the dental stone was poured in two stages. Spacers were used over the abutment analogs (rubber tubes) and type IV dental stone was poured around the abutment analogs in the conventional way. After the stone had hardened completely, the spacers were removed and more stone was inserted in the spaces created. Six strain-gauges (Excel Ltd.), positioned in a cast bar, which was dimensionally accurate (perfect fit) to the master model, recorded the microstrains generated by each specimen. Data were analyzed statistically by the variance analysis (ANOVA) and Tukey's test (α= 5%). Results: The microstrain values (με) were (mean±SD): GA: 263.7±109.07με, and GB: 193.73±78.83με. Conclusion: There was no statistical difference between the two methods studied. PMID:19089137

  11. The Influence of Implant Abutment Surface Roughness and the Type of Cement on Retention of Implant Supported Crowns

    PubMed Central

    Reddy, M. Sushender; Reddy, C. Rajaneesh; Pithani, Padmaja; R, Santosh Kumar; Kulkarni, Ganesh

    2015-01-01

    Objectives: To provide relative data on the retentive characters of the commonly used cements on different implant abutment surfaces. Materials and Methods: A total of 20 implant abutments were divided into 2 groups. Ten implants were unaltered and ten were air borne particle abraded with 50μ aluminium oxide. Three luting agents (Tempbond, IRM and ImProv) were used to secure the crowns to abutments. All the crowns were removed from the abutment with an Instron machine at 0.5mm per minute and tensile bond strengths were recorded. Statistical analysis was performed using Anova, Paired t-test and Post-Hoc tests. Results: IRM showed the highest mean tensile strength among the three cements when used with treated and untreated implant abutment surfaces. Change in the abutment surface roughness had no effect on the mean tensile bond strength of TempBond and IRM cements, whereas ImProv cement showed reduced tensile strength with sandblasted surface. Conclusion: When increased retention is required IRM cement with either sandblasted or milled surface could be used and when retrievability is required cements of choice could be either TempBond or ImProv. PMID:25954694

  12. The effect of implant splinting on the load distribution in bone bed around implant-supported fixed prosthesis with different framework materials: A finite element study.

    PubMed

    Hasan, I; Bourauel, C; Keilig, L; Stark, H; Lückerath, W

    2015-05-01

    Analysing the influence of implant splinting and its relation to different framework materials is a complex issue. The stiffness of framework materials and the overload of the implant system directly affect the final transferred load of the bone around implants. A finite element model of a long-span cementable implant-supported fixed prosthesis was created. Three materials were analysed for the framework: Titanium, gold alloy, and zirconia. The connection screws were first preloaded with 200 N. Two loading conditions were studied: The implant at the molar region was first loaded without splinting to the framework, and in the second condition, the implant was splinted to the framework. A total force of 500 N and 1000 N in 30° from the long axis of the framework were applied in buccal or distal direction on the implant system. The stresses and strains within the framework materials, implant system, and bone bed around the supporting implants were analysed. Loading the implant distally was associated with high stresses within the implant system in comparison to buccal loading. By splinting the implant, the stress in the implant system was reduced from 5393 MPa to 2942 MPa. Buccal loading of the implant was more critical than the distal loading. In the splinted condition of the implant, the stresses in the cortical bone were reduced from 570 MPa to 275 MPa. PMID:25640904

  13. Mandibular reconstruction with a prefabricated free vascularized fibula and implant-supported prosthesis based on fully three-dimensional virtual planning.

    PubMed

    Freudlsperger, Christian; Bodem, Jens Philipp; Engel, Eva; Hoffmann, Jürgen

    2014-05-01

    Because optimal reconstruction of maxillofacial defects requires functional rehabilitation, the current study demonstrates the successful secondary reconstruction of a large mandibular continuity defect using a fully digitally planned prefabricated free vascularized fibula with immediate implant-supported prosthodontic restoration. A 56-year-old man presented with a large mandibular continuity defect after resection of an enlarged squamous cell carcinoma arising from the floor of the mouth. For secondary reconstruction, the shape of the neomandible and implant position for support of the lower prosthesis were planned virtually. The combined cutting and drilling guide was printed in 3 dimensions. In a 2-step surgical approach, first, the implants were inserted into the fibula and covered with a split-thickness skin graft to form a neogingiva. In a second operation, the fibula was harvested, osteotomized, and fixed with the denture on the preinserted implants. The fibula was placed to its final position guided by the occlusion. Using three-dimensional virtual backward planning, it was feasible to perform a mandibular reconstruction with immediate prosthetic rehabilitation. PMID:24670276

  14. Impact of Platelet-Rich Plasma on Bone Height Changes around Platform Switched Implants Supporting Mandibular Overdentures in Controlled Diabetic Patients

    PubMed Central

    Ibraheem, Eman Mostafa Ahmed; Eldeen, Amany Mohy

    2015-01-01

    BACKGROUND: The platform switching concept was recently introduced to implant dentistry involving the reduction of restoration abutment diameter with respect to the diameter of dental implant. Long-term follow-up around these implants showed higher levels of bone preservation and proper stress distribution and improved esthetics. AIM: The aim of the present study was to evaluate the changes in bone height by means of radiographic examination around platform switched implant supporting mandibular overdentures in controlled diabetic patients. SUBJECTS AND METHODS: Fourteen male complete edentulous patients were selected and enrolled in a follow-up study plan. Split mouth technique was applied; one side implant chosen randomly with Platelet-rich-plasma (PRP) and the other without PRP, bone height changes was assessed by Cone Beam Computed Tomography (CBCT) radiographic examination after 3 months, 6 months, 9 months and 1 year later. RESULTS: There was increase in bone height loss in both sides but with no statistical significance difference between the two sides after 3 months, 6 months, 9 months and 1 year respectively. CONCLUSION: The result of this article satisfied the patients both esthetically and functionally with recorded increase in bone height loss. PMID:27275316

  15. Single-station cross-correlation analysis of ambient seismic noise: application to stations in the surroundings of the 2008 Iwate-Miyagi Nairiku earthquake

    NASA Astrophysics Data System (ADS)

    Hobiger, Manuel; Wegler, Ulrich; Shiomi, Katsuhiko; Nakahara, Hisashi

    2014-07-01

    We introduce the single-station cross-correlation (SC) technique of processing ambient seismic noise and compare its results with the established cross-correlation (CC) and autocorrelation (AC) techniques. While CC is the correlation of the signals of two seismic stations with each other and AC is the correlation of a signal with itself, SC is the correlation of two different components of a single three-component seismic sensor. The comparison of the three different correlation techniques shows that CCs give the best results at frequencies below 0.5 Hz and that SCs give the best results at higher frequencies. In all three processing techniques, ambient seismic noise is correlated in order to reconstruct the Green's function describing the wave propagation between the first and the second sensor. By relating the coda parts of the daily Green's functions with the long-term reference Green's functions, shear wave velocity changes are determined. Here, we apply this technique to the data of 20 seismic stations in the surroundings of the fault zone of the Iwate-Miyagi Nairiku earthquake (MW = 6.9), which occurred on 2008 June 13, UTC (2008 June 14, Japan Standard Time) in the northern part of the Japanese island Honshu. The data range from 2008 January to 2011 June and therefore include the Tohoku earthquake (MW = 9.0), which occurred on 2011 March 11, off the coast of northern Honshu. The data are analysed in five different frequency ranges between 0.125 and 4.0 Hz. The data show coseismic velocity changes for both earthquakes followed by a post-seismic velocity recovery. In general, the coseismic velocity changes increase with frequency. For the Iwate-Miyagi Nairiku earthquake, the strongest velocity changes occur close to the fault zone. Quickly recovering coseismic velocity changes can be separated from changes not recovering during the study period. For the Tohoku earthquake, the complete area is affected by coseismic velocity changes. A modelling of the depth of

  16. Visual Surround Suppression in Schizophrenia

    PubMed Central

    Tibber, Marc S.; Anderson, Elaine J.; Bobin, Tracy; Antonova, Elena; Seabright, Alice; Wright, Bernice; Carlin, Patricia; Shergill, Sukhwinder S.; Dakin, Steven C.

    2013-01-01

    Compared to unaffected observers patients with schizophrenia (SZ) show characteristic differences in visual perception, including a reduced susceptibility to the influence of context on judgments of contrast – a manifestation of weaker surround suppression (SS). To examine the generality of this phenomenon we measured the ability of 24 individuals with SZ to judge the luminance, contrast, orientation, and size of targets embedded in contextual surrounds that would typically influence the target’s appearance. Individuals with SZ demonstrated weaker SS compared to matched controls for stimuli defined by contrast or size, but not for those defined by luminance or orientation. As perceived luminance is thought to be regulated at the earliest stages of visual processing our findings are consistent with a suppression deficit that is predominantly cortical in origin. In addition, we propose that preserved orientation SS in SZ may reflect the sparing of broadly tuned mechanisms of suppression. We attempt to reconcile these data with findings from previous studies. PMID:23450069

  17. Sequence Analysis of a 282-Kilobase Region Surrounding the Citrus Tristeza Virus Resistance Gene (Ctv) Locus in Poncirus trifoliata L. Raf.1

    PubMed Central

    Yang, Zhong-Nan; Ye, Xin-Rong; Molina, Joe; Roose, Mikeal L.; Mirkov, T. Erik

    2003-01-01

    Citrus tristeza virus (CTV) is the major virus pathogen causing significant economic damage to citrus worldwide, and a single dominant gene, Ctv, provides broad spectrum resistance to CTV in Poncirus trifoliata L. Raf. Ctv was physically mapped to a 282-kb region using a P. trifoliata bacterial artificial chromosome library. This region was completely sequenced to about 8× coverage using a shotgun sequencing strategy and primer walking for gap closure. Sequence analysis predicts 22 putative genes, two mutator-like transposons and eight retrotransposons. This sequence analysis also revealed some interesting features of this region of the P. trifoliata genome: a disease resistance gene cluster with seven members and eight retrotransposons clustered in a 125-kb gene-poor region. Comparative sequence analysis suggests that six genes in the Ctv region have significant sequence similarity with their orthologs in bacterial artificial chromosome clones F7H2 and F21T11 from Arabidopsis chromosome I. However, the analysis of gene colinearity between P. trifoliata and Arabidopsis indicates that Arabidopsis genome sequence information may be of limited use for positional gene cloning in P. trifoliata and citrus. Analysis of candidate genes for Ctv is also discussed. PMID:12586873

  18. Sequence analysis of a 282-kilobase region surrounding the citrus Tristeza virus resistance gene (Ctv) locus in Poncirus trifoliata L. Raf.

    PubMed

    Yang, Zhong-Nan; Ye, Xin-Rong; Molina, Joe; Roose, Mikeal L; Mirkov, T Erik

    2003-02-01

    Citrus tristeza virus (CTV) is the major virus pathogen causing significant economic damage to citrus worldwide, and a single dominant gene, Ctv, provides broad spectrum resistance to CTV in Poncirus trifoliata L. Raf. Ctv was physically mapped to a 282-kb region using a P. trifoliata bacterial artificial chromosome library. This region was completely sequenced to about 8x coverage using a shotgun sequencing strategy and primer walking for gap closure. Sequence analysis predicts 22 putative genes, two mutator-like transposons and eight retrotransposons. This sequence analysis also revealed some interesting features of this region of the P. trifoliata genome: a disease resistance gene cluster with seven members and eight retrotransposons clustered in a 125-kb gene-poor region. Comparative sequence analysis suggests that six genes in the Ctv region have significant sequence similarity with their orthologs in bacterial artificial chromosome clones F7H2 and F21T11 from Arabidopsis chromosome I. However, the analysis of gene colinearity between P. trifoliata and Arabidopsis indicates that Arabidopsis genome sequence information may be of limited use for positional gene cloning in P. trifoliata and citrus. Analysis of candidate genes for Ctv is also discussed. PMID:12586873

  19. Molecular Analysis of the Sequences Surrounding blaOXA-45 Reveals Acquisition of This Gene by Pseudomonas aeruginosa via a Novel ISCR Element, ISCR5▿

    PubMed Central

    Li, Hongyang; Walsh, Timothy R.; Toleman, Mark A.

    2009-01-01

    The blaOXA-45 gene of Pseudomonas aeruginosa 07-406 is driven by a promoter found within a truncated ISPme1 insertion sequence. The gene is located between nonidentical repeats of a new ISCR element, ISCR5, which is likely responsible for its acquisition. Sequence analysis indicates that ISCR5 is a chimera of ISCR3 and ISCR16. PMID:19064894

  20. Opportunity's Surroundings on Sol 1818

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,818th Martian day, or sol, of Opportunity's surface mission (March 5, 2009). South is at the center; north at both ends.

    The rover had driven 80.3 meters (263 feet) southward earlier on that sol. Tracks from the drive recede northward in this view.

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

    This view is presented as a cylindrical projection with geometric seam correction.

  1. On the potential of an RST-based analysis of the MODIS-derived chl-a product over Condor seamount and surrounding areas (Azores, NE Atlantic)

    NASA Astrophysics Data System (ADS)

    Ciancia, Emanuele; Magalhães Loureiro, Clara; Mendonça, Ana; Coviello, Irina; Di Polito, Carmine; Lacava, Teodosio; Pergola, Nicola; Satriano, Valeria; Tramutoli, Valerio; Martins, Ana

    2016-07-01

    Oceanographic cruises have been conducted on the Condor seamount (SW Faial Island, Azores archipelago, NE Atlantic) since 2009 to collect in situ data and understand potential seamount effects on local biodiversity. Satellite data have been concurrently collected to infer the space-time upper-ocean optical property variability and the associated physical processes. The main limitation of this analysis is the persistent and significant cloud coverage above the region that, especially in some seasons, can significantly hinder satellite data availability. This study was meant to test the robust satellite technique (RST) over the Condor seamount, assess its capability to estimate multiyear trends and identify space-time anomalies. To this aim, 11-year MODIS/AQUA level 2-derived chlorophyll-a (chl-a) data were used. Results achieved for October 2010 show, within a large-scale analysis, the presence of well-defined areas of near-surface chl-a anomalies, highlighting the occurrence of a trapping effect due to flow-topography interaction processes. Regarding the Condor area, the chl-a anomalies detected along the eastern side of the seamount were linked to a strong vertical mixing that provided sufficient inorganic nutrients requested for productivity. The achieved results, whose accuracy was also tested through a comparison with in situ data, are consistent with those independently obtained by other authors who described the phytoplankton variability around the Condor seamount. This study shows the high potential of the RST approach to assess the chl-a variability in the space-time domain in oligotrophic regions such as the Azores, allowing the identification of the most important areas to be preserved and/or managed.

  2. Effect of labiolingual inclination of a maxillary central incisor and surrounding alveolar bone loss on periodontal stress: A finite element analysis

    PubMed Central

    Choi, Sung-Hwan; Kim, Young-Hoon; Lee, Kee-Joon

    2016-01-01

    Objective The aim of this study was to investigate whether labial tooth inclination and alveolar bone loss affect the moment per unit of force (Mt/F) in controlled tipping and consequent stresses on the periodontal ligament (PDL). Methods Three-dimensional models (n = 20) of maxillary central incisors were created with different labial inclinations (5°, 10°, 15°, and 20°) and different amounts of alveolar bone loss (0, 2, 4, and 6 mm). The Mt/F necessary for controlled tipping (Mt/Fcont) and the principal stresses on the PDL were calculated for each model separately in a finite element analysis. Results As labial inclination increased, Mt/Fcont and the length of the moment arm decreased. In contrast, increased alveolar bone loss caused increases in Mt/Fcont and the length of the moment arm. When Mt/F was near Mt/Fcont, increases in Mt/F caused compressive stresses to move from a predominantly labial apical region to a palatal apical position, and tensile stresses in the labial area moved from a cervical position to a mid-root position. Although controlled tipping was applied to the incisors, increases in alveolar bone loss and labial tooth inclination caused increases in maximum compressive and tensile stresses at the root apices. Conclusions Increases in alveolar bone loss and labial tooth inclination caused increases in stresses that might cause root resorption at the root apex, despite the application of controlled tipping to the incisors. PMID:27226961

  3. The significance of cone beam computed tomography for the visualization of anatomical variations and lesions in the maxillary sinus for patients hoping to have dental implant-supported maxillary restorations in a private dental office in Japan

    PubMed Central

    2014-01-01

    Objectives The purpose of the present study was to elucidate the significance of cone bean computed tomography (CBCT) for patients hoping to undergo implant-supported restorations of the maxilla. Therefore, two studies were planned. One was to compare the prevalence of anatomic variations and lesions in the maxillary sinus on CBCT of patients hoping to undergo implant-supported restorations of the maxilla with that in patients with other chief complaints in a private dental office in Japan. The other study was to elucidate the limitations of panoramic radiographs in the detection of anatomic variations and lesions in the maxillary sinus. Study design Sixty-one pairs of panoramic radiographs and CBCT were retrospectively analyzed in two groups of patients, those who hoped to undergo implant-supported restorations in the maxilla (Implant group) and those who did not (Non-implant group). The presence of anatomic variations and lesions in the maxillary sinus were analyzed. Results The detection rate of mucosal thickening was significantly higher in the Implant group than in the Non-implant group. The detection rates for the features analyzed were significantly lower on panoramic radiographs. In particular, the detection rates of internal and anterior locations of some features were noticeably lower on panoramic radiographs. A significant relationship was found between the change in the detection rate on panoramic radiographs and the widths of mucosal thickening or the lengths of the major axis of SOLs in the maxillary sinus. If the width of mucosal thickening or the length of the major axis of SOLs was <3 mm or <4 mm, respectively, the detection rate on panoramic radiographs was significantly decreased. Conclusion CBCT is important for patients hoping to undergo implant-supported restorations of the maxilla because of the mucosal thickening in the maxillary sinus in such patients and their lower detection rates on panoramic radiographs. PMID:24884983

  4. Opportunity's Surroundings on Sol 1687

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on the 1,687th Martian day, or sol, of its surface mission (Oct. 22, 2008).

    Opportunity had driven 133 meters (436 feet) that sol, crossing sand ripples up to about 10 centimeters (4 inches) tall. The tracks visible in the foreground are in the east-northeast direction.

    Opportunity's position on Sol 1687 was about 300 meters southwest of Victoria Crater. The rover was beginning a long trek toward a much larger crater, Endeavour, about 12 kilometers (7 miles) to the southeast.

    This view is presented as a cylindrical projection with geometric seam correction.

  5. Opportunity's Surroundings on Sol 1798

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 180-degree view of the rover's surroundings during the 1,798th Martian day, or sol, of Opportunity's surface mission (Feb. 13, 2009). North is on top.

    The rover had driven 111 meters (364 feet) southward on the preceding sol. Tracks from that drive recede northward in this view. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches).

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

    This view is presented as a cylindrical projection with geometric seam correction.

  6. Feature-based attention modulates surround suppression

    PubMed Central

    Flevaris, Anastasia V.; Murray, Scott O.

    2015-01-01

    Stimuli appearing in the surround of the classical receptive field (CRF) can reduce neuronal firing and perceived contrast of a preferred stimulus in the CRF, a phenomenon referred to as surround suppression. Suppression is greatest when the surrounding stimulus has the same orientation and spatial frequency (SF) as the central target. Although spatial attention has been shown to influence surround suppression, the effects of feature-based attention have yet to be characterized. Using behavioral contrast adaptation in humans, we examined center-surround interactions between SF and orientation, and asked whether attending to one feature dimension versus the other influenced suppression. A center-surround triplet comprised of a central target Gabor and two flanking Gabors were used for adaptation. The flankers could have the same SF and orientation as the target, or differ in one or both of the feature dimensions. Contrast thresholds were measured for the target before and after adapting to center-surround triplets, and postadaptation thresholds were taken as an indirect measure of surround suppression. Both feature dimensions contributed to surround suppression and did not summate. Moreover, when center and surround had the same feature value in one dimension (e.g., same orientation) but had different values in the other dimension (e.g., different SF), there was more suppression when attention was directed to the feature dimension that matched between center and surround than when attention was directed to the feature dimension that differed. These results demonstrate that feature-based attention can influence center-surround interactions by enhancing the effects of the attended dimension. PMID:25630380

  7. iTRAQ analysis of hepatic proteins in free-living Mus spretus mice to assess the contamination status of areas surrounding Doñana National Park (SW Spain).

    PubMed

    Abril, Nieves; Chicano-Gálvez, Eduardo; Michán, Carmen; Pueyo, Carmen; López-Barea, Juan

    2015-08-01

    This work aims to develop and integrate new -omics tools that would be applicable to different ecosystem types for a technological updating of environmental evaluations. We used a 2nd-generation (iTRAQ-8plex) proteomic approach to identify/quantify proteins differentially expressed in the liver of free-living Mus spretus mice from Doñana National Park or its proximities. Mass spectrometry was performed in an LTQ Orbitrap system for iTRAQ reporter ion quantitation and protein identification using a Mus musculus database as reference. A prior IEF step improved the separation of the complex peptide mixture. Over 2000 identified proteins were altered, of which 118 changed by ≥2.5-fold in mice from at least two problem sites. Part of the results obtained with the iTRAQ analysis was confirmed by Western blot. Over 75% of the 118 proteins were upregulated in animals captured at polluted sites and only 16 proteins were downregulated. Upregulated proteins were involved in stress response; cell proliferation and apoptosis; signal transduction; metastasis or tumour suppression; xenobiotic export or vesicular trafficking; and metabolism. The downregulated proteins, all potentially harmful, were classified as oncoproteins and proteins favouring genome instability. The iTRAQ results presented here demonstrated that the survival of hepatic cells is compromised in animals living at polluted sites, which showed deep alterations in metabolism and the signalling pathways. The identified proteins may be useful as biomarkers of environmental pollution and provide insight about the metabolic pathways and/or physiological processes affected by pollutants in DNP and its surrounding areas. PMID:25847312

  8. AERIAL OF VEHICLE ASSEMBLY BUILDING & SURROUNDING AREA

    NASA Technical Reports Server (NTRS)

    1977-01-01

    AERIAL OF VEHICLE ASSEMBLY BUILDING & SURROUNDING AREA KSC-377C-0082.41 116-KSC-377C-82.41, P-15877, ARCHIVE-04151 Aerial view - Shuttle construction progress - VAB and Orbiter Processing Facilities - direction northwest.

  9. Impacts of Artificial Reefs on Surrounding Ecosystems

    NASA Astrophysics Data System (ADS)

    Manoukian, Sarine

    Artificial reefs are becoming a popular biological and management component in shallow water environments characterized by soft seabed, representing both important marine habitats and tools to manage coastal fisheries and resources. An artificial reef in the marine environment acts as an open system with exchange of material and energy, altering the physical and biological characteristics of the surrounding area. Reef stability will depend on the balance of scour, settlement, and burial resulting from ocean conditions over time. Because of the unstable nature of sediments, they require a detailed and systematic investigation. Acoustic systems like high-frequency multibeam sonar are efficient tools in monitoring the environmental evolution around artificial reefs, whereas water turbidity can limit visual dive and ROV inspections. A high-frequency multibeam echo sounder offers the potential of detecting fine-scale distribution of reef units, providing an unprecedented level of resolution, coverage, and spatial definition. How do artificial reefs change over time in relation to the coastal processes? How accurately does multibeam technology map different typologies of artificial modules of known size and shape? How do artificial reefs affect fish school behavior? What are the limitations of multibeam technology for investigating fish school distribution as well as spatial and temporal changes? This study addresses the above questions and presents results of a new approach for artificial reef seafloor mapping over time, based upon an integrated analysis of multibeam swath bathymetry data and geoscientific information (backscatter data analysis, SCUBA observations, physical oceanographic data, and previous findings on the geology and sedimentation processes, integrated with unpublished data) from Senigallia artificial reef, northwestern Adriatic Sea (Italy) and St. Petersburg Beach Reef, west-central Florida continental shelf. A new approach for observation of fish

  10. Management of a Fractured Multiunit Maxillary Implant-Supported Fixed Prosthesis with Stripped Abutment Screws Using a Hybrid Cement-Retained and Screw-Retained Design: A 5-Year Follow-Up Clinical Report.

    PubMed

    Al Amri, Mohammad D

    2016-06-01

    Fracture and loosening of implant-supported prostheses (ISPs) are complications encountered in routine dental practice. In the present report, management of a fractured maxillary full-arch cement-retained (CR) fixed dental prosthesis supported by six implants is presented. Due to stripped screws, complications were encountered that prevented the retrieval of two of the six abutment screws, which was managed by using a hybrid retention approach, whereby a single full-arch CR and screw-retained (SR) ISP was used. The techniques used to successfully retrieve four of the abutment screws are described. The final retention design involved a combination of three CR and three SR restorations, which offers the advantages of both retention designs. PMID:26713868

  11. The effect of implant number and position on the stress behavior of mandibular implant retained overdentures: A three-dimensional finite element analysis.

    PubMed

    Topkaya, Tolga; Solmaz, Murat Yavuz

    2015-07-16

    The present study evaluated the effects of ball anchor abutment attached to implants with a 4.30 mm diameter and 11 mm insert length on stress distribution in a patient without any remaining teeth in the lower jaw. In the study, the stress analysis was performed for five different configurations (2 with 4 implant-supported and 3 with 2 implant-supported) and three different loading types using ANSYS Workbench software. The stresses measured in the 4 implant-supported models were lower compared to the stresses measured in the 2 implant-supported models. The stresses on the implants intensified on the cervical region of the implants. When the effects of the loading sites on the stress were examined, the loading on the first molar tooth produced the highest stresses on the implants. PMID:25862522

  12. The biological activity of propolis-containing toothpaste on oral health environment in patients who underwent implant-supported prosthodontic rehabilitation.

    PubMed

    Morawiec, Tadeusz; Dziedzic, Arkadiusz; Niedzielska, Iwona; Mertas, Anna; Tanasiewicz, Marta; Skaba, Dariusz; Kasperski, Jacek; Machorowska-Pieniążek, Agnieszka; Kucharzewski, Marek; Szaniawska, Karolina; Więckiewicz, Włodzimierz; Więckiewicz, Mieszko

    2013-01-01

    The soft and periodontal tissues surrounding dental implants are particularly susceptible to bacteria invasion and inflammatory reactions due to complex histological structures. This study was carried out to investigate the influence of a propolis-containing hygienic agent on selected oral health parameters, oral microflora, and the condition of periodontal health. Sixteen subjects who underwent an oral rehabilitation with dental implants were selected and randomly assigned into two groups, which received a newly formulated propolis-containing toothpaste (3% (CA)) or a negative control without an active ingredient (CC). Approximal plaque index (API), oral hygiene index (OHI, debris component), and sulcus bleeding index (SBI) were assessed in three subsequent stages. During the first and last examinations, the swabs were employed for microbiological inoculation. Propolis-containing toothpaste was found to be distinctively effective in improving oral health and the occurrence of gingivitis triggered by dental plaque. The qualitative and quantitative changes in oral bacteria spectrum were observed. Antibacterial measures containing propolis might be used as a natural adjuvant to other active substances in individuals with a high risk of periodontal problems against pathogenic oral microflora. PMID:23762153

  13. The Biological Activity of Propolis-Containing Toothpaste on Oral Health Environment in Patients Who Underwent Implant-Supported Prosthodontic Rehabilitation

    PubMed Central

    Morawiec, Tadeusz; Dziedzic, Arkadiusz; Niedzielska, Iwona; Mertas, Anna; Tanasiewicz, Marta; Skaba, Dariusz; Kasperski, Jacek; Machorowska-Pieniążek, Agnieszka; Kucharzewski, Marek; Szaniawska, Karolina; Więckiewicz, Włodzimierz; Więckiewicz, Mieszko

    2013-01-01

    The soft and periodontal tissues surrounding dental implants are particularly susceptible to bacteria invasion and inflammatory reactions due to complex histological structures. This study was carried out to investigate the influence of a propolis-containing hygienic agent on selected oral health parameters, oral microflora, and the condition of periodontal health. Sixteen subjects who underwent an oral rehabilitation with dental implants were selected and randomly assigned into two groups, which received a newly formulated propolis-containing toothpaste (3% (CA)) or a negative control without an active ingredient (CC). Approximal plaque index (API), oral hygiene index (OHI, debris component), and sulcus bleeding index (SBI) were assessed in three subsequent stages. During the first and last examinations, the swabs were employed for microbiological inoculation. Propolis-containing toothpaste was found to be distinctively effective in improving oral health and the occurrence of gingivitis triggered by dental plaque. The qualitative and quantitative changes in oral bacteria spectrum were observed. Antibacterial measures containing propolis might be used as a natural adjuvant to other active substances in individuals with a high risk of periodontal problems against pathogenic oral microflora. PMID:23762153

  14. Cemented and screw-retained implant-supported single-tooth restorations in the molar mandibular region: A retrospective comparison study after an observation period of 1 to 4 years

    PubMed Central

    Peñarrocha-Diago, Miguel; Pradíes, Guillermo; Sola-Ruiz, María-Fernanda; Agustín-Panadero, Rubén

    2015-01-01

    Objectives: The aim of this study was to evaluate the survival and compare the appearance of different mechanical and biological complications, in screw-retained and cemented-retained single-tooth implant-supported restorations localized in the molar mandibular region, over a period of 1 to 4 years. Material and Methods: A retrospective study was carried out with a total of eighty implant-supported restorations, which were placed in eighty patients for prosthetic rehabilitation of a mandibular molar. Forty patients were rehabilitated with a cemented-retained restoration and the other forty with a screw-retained restoration. The presence of the following complications was recorded for both types of prostheses: Fractures of the ceramic veneering, loosening screws, mucositis and peri-implantitis. Debonding of the restoration was analyzed in the cemented-retained restoration group. The clinical survival of crowns was analyzed with a Kaplan-Meier test and the clinical complications were compared, using a Student t test and Log-rank test. Results: 27 patients registered some complication. The average rate of complications was 37,5% for cemented-retained restorations and 30% for screw-retained restorations. The complications more common in the cemented-retained restoration were the presence of mucositis (14,87%), while in the screw-retained restorations was the loosening screw (20%). Student t test and Log-Rank test found significant differences (p=0,001) between the screw loosening and presence of mucositis. Conclusions: The cemented-retained restorations seem to prevent screw loosening, but the presence of cement seem to increase the complications around the soft tissues, however in the screw-retained restorations the presence of mucositis and peri-implantitis are lower than cemented-retained restorations. The incidence of fracture of ceramic veneering was similar in both groups. Key words:Screw-retained restorations, cemented-retained restorations, screw loosening

  15. Identifying separate components of surround suppression

    PubMed Central

    Schallmo, Michael-Paul; Murray, Scott O.

    2016-01-01

    Surround suppression is a well-known phenomenon in which the response to a visual stimulus is diminished by the presence of neighboring stimuli. This effect is observed in neural responses in areas such as primary visual cortex, and also manifests in visual contrast perception. Studies in animal models have identified at least two separate mechanisms that may contribute to surround suppression: one that is monocular and resistant to contrast adaptation, and another that is binocular and strongly diminished by adaptation. The current study was designed to investigate whether these two mechanisms exist in humans and if they can be identified psychophysically using eye-of-origin and contrast adaptation manipulations. In addition, we examined the prediction that the monocular suppression component is broadly tuned for orientation, while suppression between eyes is narrowly tuned. Our results confirmed that when center and surrounding stimuli were presented dichoptically (in opposite eyes), suppression was orientation-tuned. Following adaptation in the surrounding region, no dichoptic suppression was observed, and monoptic suppression no longer showed orientation selectivity. These results are consistent with a model of surround suppression that depends on both low-level and higher level components. This work provides a method to assess the separate contributions of these components during spatial context processing in human vision. PMID:26756172

  16. Stereoscopic surround displays using interference filters

    NASA Astrophysics Data System (ADS)

    Peikert, Silvio; Gerhardt, Jérémie

    2012-03-01

    To achieve stereoscopy on surround displays interference filters have some advantages over other techniques. However these filters introduce strong color differences between the projectors, which may reveal that the display is compound by multiple projectors. This article presents methods for a computationally efficient correction of the colorimetric properties of multi-projector surround displays. This correction is based on automated measurements by multiple cameras and a spectrometer. The described methods were validated by applying them to a stereoscopic dome display made up of 16 high definition projectors equipped with Infitec filters. On that display we achieved a significant improvement of the colorimetric properties compared to regular soft-edge blending. Our reference setup shows that the multi-projector approach combined with interference filters allows to build highly immersive stereoscopic surround displays fulfilling today's requirements on spatial resolution, frame rates and interaction latencies.

  17. Center-Surround Inhibition in Working Memory.

    PubMed

    Kiyonaga, Anastasia; Egner, Tobias

    2016-01-11

    Directing visual attention toward a particular feature or location in the environment suppresses processing of nearby stimuli [1-4]. Echoing the center-surround organization of retinal ganglion cell receptive fields [5], and biasing of competitive local neuronal dynamics in favor of task-relevant stimuli [6], this "inhibitory surround" attention mechanism accentuates the demarcation between task-relevant and irrelevant items. Here, we show that internally maintaining a color stimulus in working memory (WM), rather than visually attending the stimulus in the external environment, produces an analogous pattern of inhibition for stimuli that are nearby in color space. Replicating a well-known effect of attentional capture by stimuli that match WM content [7], visual attention was biased toward (task-irrelevant) stimuli that exactly matched a WM item. This bias was curtailed, however, for stimuli that were very similar to the WM content (i.e., within the inhibitory zone surrounding the focus of WM) and recovered for less similar stimuli (i.e., beyond the bounds of the inhibitory surround). Moreover, the expression of this inhibition effect was positively associated with WM performance across observers. In a second experiment, inhibition also occurred between two similar items simultaneously held in WM. This suggests that maintenance in WM is characterized by an excitatory peak centered on the focus of (internal) attention, surrounded by an inhibitory zone to limit interference by irrelevant and confusable representations. Here, thus, we show for the first time that the same center-surround selection mechanism that focuses visual attention on sensory stimuli also selectively maintains internally activated representations in WM. PMID:26711496

  18. Issues Surrounding Children with Developmental Coordination Disorder

    ERIC Educational Resources Information Center

    Sugden, David; Kirby, Amanda; Dunford, Carolyn

    2008-01-01

    Like other developmental disorders such as Attention Deficit Hyperactivity Disorder, specific language impairment and dyslexia, there is no shortage of debate surrounding the condition of Developmental Coordination Disorder. The present article takes a global view of many of these debatable issues, starting with definition and terminology, moving…

  19. A three-dimensional finite element analysis of a passive and friction fit implant abutment interface and the influence of occlusal table dimension on the stress distribution pattern on the implant and surrounding bone

    PubMed Central

    Sarfaraz, Hasan; Paulose, Anoopa; Shenoy, K. Kamalakanth; Hussain, Akhter

    2015-01-01

    Aims: The aim of the study was to evaluate the stress distribution pattern in the implant and the surrounding bone for a passive and a friction fit implant abutment interface and to analyze the influence of occlusal table dimension on the stress generated. Materials and Methods: CAD models of two different types of implant abutment connections, the passive fit or the slip-fit represented by the Nobel Replace Tri-lobe connection and the friction fit or active fit represented by the Nobel active conical connection were made. The stress distribution pattern was studied at different occlusal dimension. Six models were constructed in PRO-ENGINEER 05 of the two implant abutment connection for three different occlusal dimensions each. The implant and abutment complex was placed in cortical and cancellous bone modeled using a computed tomography scan. This complex was subjected to a force of 100 N in the axial and oblique direction. The amount of stress and the pattern of stress generated were recorded on a color scale using ANSYS 13 software. Results: The results showed that overall maximum Von Misses stress on the bone is significantly less for friction fit than the passive fit in any loading conditions stresses on the implant were significantly higher for the friction fit than the passive fit. The narrow occlusal table models generated the least amount of stress on the implant abutment interface. Conclusion: It can thus be concluded that the conical connection distributes more stress to the implant body and dissipates less stress to the surrounding bone. A narrow occlusal table considerably reduces the occlusal overload. PMID:26929518

  20. Clutter modeling of the Denver Airport and surrounding areas

    NASA Technical Reports Server (NTRS)

    Harrah, Steven D.; Delmore, Victor E.; Onstott, Robert G.

    1991-01-01

    To accurately simulate and evaluate an airborne Doppler radar as a wind shear detection and avoidance sensor, the ground clutter surrounding a typical airport must be quantified. To do this, an imaging airborne Synthetic Aperture Radar (SAR) was employed to investigate and map the normalized radar cross sections (NRCS) of the ground terrain surrounding the Denver Stapleton Airport during November of 1988. Images of the Stapleton ground clutter scene were obtained at a variety of aspect and elevation angles (extending to near-grazing) at both HH and VV polarizations. Presented here, in viewgraph form with commentary, are the method of data collection, the specific observations obtained of the Denver area, a summary of the quantitative analysis performed on the SAR images to date, and the statistical modeling of several of the more interesting stationary targets in the SAR database. Additionally, the accompanying moving target database, containing NRCS and velocity information, is described.

  1. INFLUENCE OF DIFFERENT CANTILEVER EXTENSIONS AND GLASS OR POLYARAMID REINFORCEMENT FIBERS ON FRACTURE STRENGTH OF IMPLANT-SUPPORTED TEMPORARY FIXED PROSTHESIS

    PubMed Central

    Colán Guzmán, Paola; de Freitas, Fernando Furtado Antunes; Ferreira, Paulo Martins; de Freitas, César Antunes; Reis, Kátia Rodrigues

    2008-01-01

    In long-term oral rehabilitation treatments, resistance of provisional crowns is a very important factor, especially in cases of an extensive edentulous distal space. The aim of this laboratorial study was to evaluate an acrylic resin cantilever-type prosthesis regarding the flexural strength of its in-balance portion as a function of its extension variation and reinforcement by two types of fibers (glass and polyaramid), considering that literature is not conclusive on this subject. Each specimen was composed by 3 total crowns at its mesial portion, each one attached to an implant component (abutment), while the distal portion (cantilever) had two crowns. Each specimen was constructed by injecting acrylic resin into a two-part silicone matrix placed on a metallic base. In each specimen, the crowns were fabricated with either acrylic resin (control group) or acrylic resin reinforced by glass (Fibrante, Angelus) or polyaramide (Kevlar 49, Du Pont) fibers. Compression load was applied on the cantilever, in a point located 7, 14 or 21 mm from the distal surface of the nearest crown with abutment, to simulate different extensions. The specimen was fixed on the metallic base and the force was applied until fracture in a universal test machine. Each one of the 9 sub-groups was composed by 10 specimens. Flexural strength means (in kgf) for the distances of 7, 14 and 21 mm were, respectively, 28.07, 8.27 and 6.39 for control group, 31.89, 9.18 and 5.16 for Kevlar 49 and 30.90, 9.31 and 6.86 for Fibrante. Data analysis ANOVA showed statistically significant difference (p<0.05) only regarding cantilever extension. Tukey's test detected significantly higher flexural strength for the 7 mm-distance, followed by 14 and 21 mm. Fracture was complete only on specimens of non-reinforced groups. PMID:19089201

  2. Evaluation of removal forces of implant-supported zirconia copings depending on abutment geometry, luting agent and cleaning method during re-cementation

    PubMed Central

    Rödiger, Matthias; Rinke, Sven; Ehret-Kleinau, Fenja; Pohlmeyer, Franziska; Lange, Katharina; Bürgers, Ralf

    2014-01-01

    PURPOSE To evaluate the effects of different abutment geometries in combination with varying luting agents and the effectiveness of different cleaning methods (prior to re-cementation) regarding the retentiveness of zirconia copings on implants. MATERIALS AND METHODS Implants were embedded in resin blocks. Three groups of titanium abutments (pre-fabricated, height: 7.5 mm, taper: 5.7°; customized-long, height: 6.79 mm, taper: 4.8°; customized-short, height: 4.31 mm, taper: 4.8°) were used for luting of CAD/CAM-fabricated zirconia copings with a semi-permanent (Telio CS) and a provisional cement (TempBond NE). Retention forces were evaluated using a universal testing machine. Furthermore, the influence of cleaning methods (manually, manually in combination with ultrasonic bath or sandblasting) prior to re-cementation with a provisional cement (TempBond NE) was investigated with the pre-fabricated titanium abutments (height: 7.5 mm, taper: 5.7°) and SEM-analysis of inner surfaces of the copings was performed. Significant differences were determined via two-way ANOVA. RESULTS Significant interactions between abutment geometry and luting agent were observed. TempBond NE showed the highest level of retentiveness on customized-long abutments, but was negatively affected by other abutment geometries. In contrast, luting with Telio CS demonstrated consistent results irrespective of the varying abutment geometries. Manual cleaning in combination with an ultrasonic bath was the only cleaning method tested prior to re-cementation that revealed retentiveness levels not inferior to primary cementation. CONCLUSION No superiority for one of the two cements could be demonstrated because their influences on retentive strength are also depending on abutment geometry. Only manual cleaning in combination with an ultrasonic bath offers retentiveness levels after re-cementation comparable to those of primary luting. PMID:25006388

  3. Spirit's Surroundings on 'West Spur,' Sol 305

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This 360-degree panorama shows the terrain surrounding NASA's Mars Exploration Rover Spirit as of the rover's 305th martian day, or sol, (Nov. 11, 2004). At that point, Spirit was climbing the 'West Spur' of the 'Columbia Hills.' The rover had just finished inspecting a rock called 'Lutefisk' and was heading uphill toward an area called 'Machu Picchu.' Spirit used its navigational camera to take the images combined into this mosaic. The rover's location when the images were taken is catalogued as the mission's site 89, position 205. The view is presented here as a cylindrical projection with geometric seam correction.

  4. Numerical simulation on zonal disintegration in deep surrounding rock mass.

    PubMed

    Chen, Xuguang; Wang, Yuan; Mei, Yu; Zhang, Xin

    2014-01-01

    Zonal disintegration have been discovered in many underground tunnels with the increasing of embedded depth. The formation mechanism of such phenomenon is difficult to explain under the framework of traditional rock mechanics, and the fractured shape and forming conditions are unclear. The numerical simulation was carried out to research the generating condition and forming process of zonal disintegration. Via comparing the results with the geomechanical model test, the zonal disintegration phenomenon was confirmed and its mechanism is revealed. It is found to be the result of circular fracture which develops within surrounding rock mass under the high geostress. The fractured shape of zonal disintegration was determined, and the radii of the fractured zones were found to fulfill the relationship of geometric progression. The numerical results were in accordance with the model test findings. The mechanism of the zonal disintegration was revealed by theoretical analysis based on fracture mechanics. The fractured zones are reportedly circular and concentric to the cavern. Each fracture zone ruptured at the elastic-plastic boundary of the surrounding rocks and then coalesced into the circular form. The geometric progression ratio was found to be related to the mechanical parameters and the ground stress of the surrounding rocks. PMID:24592166

  5. Numerical Simulation on Zonal Disintegration in Deep Surrounding Rock Mass

    PubMed Central

    Chen, Xuguang; Wang, Yuan; Mei, Yu; Zhang, Xin

    2014-01-01

    Zonal disintegration have been discovered in many underground tunnels with the increasing of embedded depth. The formation mechanism of such phenomenon is difficult to explain under the framework of traditional rock mechanics, and the fractured shape and forming conditions are unclear. The numerical simulation was carried out to research the generating condition and forming process of zonal disintegration. Via comparing the results with the geomechanical model test, the zonal disintegration phenomenon was confirmed and its mechanism is revealed. It is found to be the result of circular fracture which develops within surrounding rock mass under the high geostress. The fractured shape of zonal disintegration was determined, and the radii of the fractured zones were found to fulfill the relationship of geometric progression. The numerical results were in accordance with the model test findings. The mechanism of the zonal disintegration was revealed by theoretical analysis based on fracture mechanics. The fractured zones are reportedly circular and concentric to the cavern. Each fracture zone ruptured at the elastic-plastic boundary of the surrounding rocks and then coalesced into the circular form. The geometric progression ratio was found to be related to the mechanical parameters and the ground stress of the surrounding rocks. PMID:24592166

  6. Investigation of land subsidence due to climate changes in surrounding areas of Urmia Lake (located in northwest of Iran) using wavelet coherence analysis of geodetic measurements and methodological data

    NASA Astrophysics Data System (ADS)

    Moghtased-Azar, K.; Mirzaei, A.; Nankali, H. R.; Tavakoli, F.

    2012-04-01

    Urmia Lake (salt lake in northwest of Iran) plays a valuable role in environment, wildlife and economy of Iran and the region, and now faces great challenges for survival. The Lake is in immediate and great danger and rapidly going to become salty desert. During the recent years and new heat wave, Iran, like many other countries are experiencing, is faced with relativity reduced rain fall. From a few years ago environment activists warned about potential dangers. Geodetic measurements, e.g., repeated leveling measurements of first order leveling network of Iran and continuous GPS measurements of Iranian Permanent GPS network of Iran (IPGN) showed that there is subsidence in surrounding areas of the lake. This paper investigates the relation between subsidence and climate changing in the area, using the wavelet coherence of the data of permanent GPS stations and daily methodological data. The results show that there is strong coherence between the subsidence phenomena induced by GPS data and climate warming from January 2009 up to end of August 2009. However, relative lake height variations computed from altimetry observations (TOPEX/POSEIDON (T/P), Jason-1 and Jason-2/OSTM) confirms maximum evaporation rates of the lake in this period.

  7. Non-linear viscoelastic finite element analysis of the effect of the length of glass fiber posts on the biomechanical behaviour of directly restored incisors and surrounding alveolar bone.

    PubMed

    Ferrari, Marco; Sorrentino, Roberto; Zarone, Fernando; Apicella, Davide; Aversa, Raffaella; Apicella, Antonio

    2008-07-01

    The study aimed at estimating the effect of insertion length of posts with composite restorations on stress and strain distributions in central incisors and surrounding bone. The typical, average geometries were generated in a FEA environment. Dentin was considered as an elastic orthotropic material, and periodontal ligament was coupled with nonlinear viscoelastic mechanical properties. The model was then validated with experimental data on displacement of incisors from published literature. Three post lengths were investigated in this study: root insertion of 5, 7, and 9 mm. For control, a sound incisor model was generated. Then, a tearing load of 50 N was applied to both sound tooth and simulation models. Post restorations did not seem to affect the strain distribution in bone when compared to the control. All simulated post restorations affected incisor biomechanics and reduced the root's deforming capability, while the composite crowns underwent a higher degree of deformation than the sound crown. No differences could be noticed in incisor stress and strain. As for the influence of post length, it was not shown to affect the biomechanics of restored teeth. PMID:18833761

  8. Predicting Maximum Lake Depth from Surrounding Topography

    PubMed Central

    Hollister, Jeffrey W.; Milstead, W. Bryan; Urrutia, M. Andrea

    2011-01-01

    Information about lake morphometry (e.g., depth, volume, size, etc.) aids understanding of the physical and ecological dynamics of lakes, yet is often not readily available. The data needed to calculate measures of lake morphometry, particularly lake depth, are usually collected on a lake-by-lake basis and are difficult to obtain across broad regions. To span the gap between studies of individual lakes where detailed data exist and regional studies where access to useful data on lake depth is unavailable, we developed a method to predict maximum lake depth from the slope of the topography surrounding a lake. We use the National Elevation Dataset and the National Hydrography Dataset – Plus to estimate the percent slope of surrounding lakes and use this information to predict maximum lake depth. We also use field measured maximum lake depths from the US EPA's National Lakes Assessment to empirically adjust and cross-validate our predictions. We were able to predict maximum depth for ∼28,000 lakes in the Northeastern United States with an average cross-validated RMSE of 5.95 m and 5.09 m and average correlation of 0.82 and 0.69 for Hydrological Unit Code Regions 01 and 02, respectively. The depth predictions and the scripts are openly available as supplements to this manuscript. PMID:21984945

  9. The Cluster of Galaxies Surrounding Cygnus A

    NASA Astrophysics Data System (ADS)

    Owen, Frazer N.; Ledlow, Michael J.; Morrison, Glenn E.; Hill, John M.

    1997-10-01

    We report optical imaging and spectroscopy of 41 galaxies in a 22' square region surrounding Cygnus A. The results show that there is an extensive rich cluster associated with Cyg A of Abell richness of at least 1 and possibly as high as 4. The velocity histogram has two peaks, one centered on Cyg A and a more significant peak redshifted by about 2060 km s-1 from the velocity of Cyg A. The dynamical centroid of the spatial distribution is also shifted somewhat to the northwest. However, statistical tests show only weak evidence that there are two distinct clusters. The entire system has a velocity dispersion of 1581 km s-1, which is slightly larger than other, well-studied examples of rich clusters.

  10. Autofluorescence of tissue surrounding malignant tumors

    NASA Astrophysics Data System (ADS)

    Lohmann, Wolfgang; Bohle, Rainer M.; Schill, Wolf-Bernhard; Vahrson, H.; Mussmann, J.

    1998-04-01

    In vitro fluorescence measurements on pap smears of ascites, pleura, or Douglas confirmed results obtained previously with different types of tissue: Cancer tissue fluoresces hardly and is surrounded by a 'fluorescence belt.' Investigations of cytological smears (e.g. Pap smears) have revealed the possible participation of granulocytes in this 'immune' reaction. Furthermore, there seems to be obvious differences in the fluorescence response of pap smears between ovarial- carcinomas and peritoneal carcinomas based on ovarial carcinoma. This observation cannot be explained yet. Because of its sensitivity and specificity the fluorescence method can be used as an additional tool for the evaluation of the tumor invasion front. Preferably it might be used for frozen sections of biopsies and surgical excisions.

  11. Opportunity's Surroundings After Sol 1820 Drive

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009). South is at the center; north at both ends.

    The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches).

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock.

    This view is presented as a cylindrical projection with geometric seam correction.

  12. Opportunity's Surroundings After Sol 1820 Drive (Polar)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009).

    This view is presented as a polar projection with geometric seam correction. North is at the top.

    The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches).

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock.

  13. Opportunity's Surroundings on Sol 1818 (Polar)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,818th Martian day, or sol, of Opportunity's surface mission (March 5, 2009). South is at the center; north at both ends.

    This view is presented as a polar projection with geometric seam correction. North is at the top.

    The rover had driven 80.3 meters (263 feet) southward earlier on that sol. Tracks from the drive recede northward in this view.

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

  14. Opportunity's Surroundings on Sol 1687 (Polar)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on the 1,687th Martian day, or sol, of its surface mission (Oct. 22, 2008).

    Opportunity had driven 133 meters (436 feet) that sol, crossing sand ripples up to about 10 centimeters (4 inches) tall. The tracks visible in the foreground are in the east-northeast direction.

    Opportunity's position on Sol 1687 was about 300 meters southwest of Victoria Crater. The rover was beginning a long trek toward a much larger crater, Endeavour, about 12 kilometers (7 miles) to the southeast.

    This view is presented as a polar projection with geometric seam correction.

  15. Opportunity's Surroundings on Sol 1687 (Vertical)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on the 1,687th Martian day, or sol, of its surface mission (Oct. 22, 2008).

    Opportunity had driven 133 meters (436 feet) that sol, crossing sand ripples up to about 10 centimeters (4 inches) tall. The tracks visible in the foreground are in the east-northeast direction.

    Opportunity's position on Sol 1687 was about 300 meters southwest of Victoria Crater. The rover was beginning a long trek toward a much larger crater, Endeavour, about 12 kilometers (7 miles) to the southeast.

    This view is presented as a vertical projection with geometric seam correction.

  16. Opportunity's Surroundings After Sol 1820 Drive (Vertical)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009).

    This view is presented as a vertical projection with geometric seam correction. North is at the top.

    The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches).

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock.

  17. Opportunity's Surroundings on Sol 1818 (Vertical)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,818th Martian day, or sol, of Opportunity's surface mission (March 5, 2009). South is at the center; north at both ends.

    This view is presented as a vertical projection with geometric seam correction. North is at the top.

    The rover had driven 80.3 meters (263 feet) southward earlier on that sol. Tracks from the drive recede northward in this view.

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

  18. Opportunity's Surroundings on Sol 1798 (Vertical)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 180-degree view of the rover's surroundings during the 1,798th Martian day, or sol, of Opportunity's surface mission (Feb. 13, 2009). North is on top.

    This view is presented as a vertical projection with geometric seam correction.

    The rover had driven 111 meters (364 feet) southward on the preceding sol. Tracks from that drive recede northward in this view. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches).

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

  19. Opportunity's Surroundings on Sol 1798 (Polar)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 180-degree view of the rover's surroundings during the 1,798th Martian day, or sol, of Opportunity's surface mission (Feb. 13, 2009). North is on top.

    This view is presented as a polar projection with geometric seam correction.

    The rover had driven 111 meters (364 feet) southward on the preceding sol. Tracks from that drive recede northward in this view. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches).

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

  20. Sharpless 170 and the surrounding interstellar medium

    NASA Astrophysics Data System (ADS)

    Roger, R. S.; McCutcheon, W. H.; Purton, C. R.; Dewdney, P. E.

    2004-10-01

    Sharpless 170 is a diffuse HII region ionized by a single main sequence O-star located near the periphery of a small dense molecular cloud at a distance of ˜2 kpc. We describe wide-field observations of the region in the radio continuum, in HI and CO-lines, and in the far-infrared which delineate the major ionized, atomic, molecular and dust components of the gas affected by the exciting star. From the thermal continuum emission we estimate the mass of ionized gas at ˜350 M⊙ within a radius of ˜7 pc. The HI (λ21 cm) and far-infrared observations show an extended low-density atomic component, of ˜1000 M⊙, within an irregular boundary surrounding the ionized gas of mean radius ˜10 pc. Mean densities in the HI and HII are similar, in the range 9-16 nucleons cm-3. CO emission shows a molecular cloud of ˜1150 M⊙ within an area 6 pc × 4 pc with densities ˜2000 nucleons cm-3. A compact infrared component coincides with the cloud. The exciting star is located on the near side of the cloud, just inside the southern periphery. Sh170 is an example of a young HII region with the ionized gas, seen in Hα emission, streaming outward in the manner of a ``champagne flow''. Although the observed velocities of the HI are close to the mean velocity of the CO cloud, the morphology of the associated atomic hydrogen closely resembles that seen in the surrounds of other young HII regions which show clear evidence of expansion of their HI. We propose that much of the HI is a diffuse dissociation zone beyond the ionization front, in directions from the star within a wide annulus, approximately transverse to the line-of-sight, between the dense photon-bounded region on the far side of the star and the density-bounded ionized flow region on the near side. In this view, much of the associated atomic gas, like the ionized gas, has been eroded from the molecular cloud in a small fraction (≤10%) of the star's main sequence lifetime.

  1. The Interstellar Medium Surrounding the Sun

    NASA Astrophysics Data System (ADS)

    Frisch, Priscilla C.; Redfield, Seth; Slavin, Jonathan D.

    2011-09-01

    The Solar System is embedded in a flow of low-density, warm, and partially ionized interstellar material that has been sampled directly by in situ measurements of interstellar neutral gas and dust in the heliosphere. Absorption line data reveal that this interstellar gas is part of a larger cluster of local interstellar clouds, which is spatially and kinematically divided into additional small-scale structures indicating ongoing interactions. An origin for the clouds that is related to star formation in the Scorpius-Centaurus OB association is suggested by the dynamic characteristics of the flow. Variable depletions observed within the local interstellar medium (ISM) suggest an inhomogeneous Galactic environment, with shocks that destroy grains in some regions. Although photoionization models of the circumheliospheric ISM do an excellent job of reproducing the observed properties of the surrounding ISM, the unknown characteristics of the very low-density hot plasma filling the Local Bubble introduces uncertainty about the source of ionization and nature of cloud boundaries. Recent observations of small cold clouds provide new insight into the processes affecting the local ISM. A fuller understanding of the local ISM can provide insights into the past and future Galactic environment of the Sun, and deeper knowledge of the astrospheres of nearby stars.

  2. Color appearance: neutral surrounds and spatial contrast.

    PubMed

    Smith, V C; Jin, Q; Pokorny, J

    1998-11-01

    The experimental data in this paper show that chromatic bars presented in alternation with equiluminant neutral-appearing bars are seen as more saturated than the same chromaticity presented as a uniform rectangle. This effect was diminished but not eliminated when test and match stimuli were presented within a slightly dimmer neutral surround. The test stimulus was a 2 x 5 degrees rectangle with a 0.7 cpd square wave grating composed of alternating equiluminant chromatic test bars and neutral bars. Asymmetric matching was used to match the test bar appearance to a uniform 2 x 5 degrees comparison rectangle. Test and comparison stimuli were presented to separate eyes in a haploscope and appeared flanking a central fixation target. Data were collected with test and inducing stimuli on the cardinal axes of color space. Test bars separated by neutral bars appeared more saturated than the comparison rectangle for both the l- and s-axis directions. Manipulation of excitation on one cardinal axis did not affect the appearance matches made for the other cardinal axis. PMID:9893836

  3. INTERSTELLAR MAGNETIC FIELD SURROUNDING THE HELIOPAUSE

    SciTech Connect

    Whang, Y. C.

    2010-02-20

    This paper presents a three-dimensional analytical solution, in the limit of very low plasma beta-ratio, for the distortion of the interstellar magnetic field surrounding the heliopause. The solution is obtained using a line dipole method that is the integration of point dipole along a semi-infinite line; it represents the magnetic field caused by the presence of the heliopause. The solution allows the variation of the undisturbed magnetic field at any inclination angle. The heliosphere is considered as having blunt-nosed geometry on the upwind side and it asymptotically approaches a cylindrical geometry having an open exit for the continuous outflow of the solar wind on the downwind side. The heliopause is treated as a magnetohydrodynamic tangential discontinuity; the interstellar magnetic field lines at the boundary are tangential to the heliopause. The interstellar magnetic field is substantially distorted due to the presence of the heliopause. The solution shows the draping of the field lines around the heliopause. The magnetic field strength varies substantially near the surface of the heliopause. The effect on the magnetic field due to the presence of the heliopause penetrates very deep into the interstellar space; the depth of penetration is of the same order of magnitude as the scale length of the heliosphere.

  4. Ultrastructure of mitochondrial nucleoid and its surroundings.

    PubMed

    Prachař, Jarmil

    2016-07-01

    Mitochondrial nucleoids (hereafter nucleoids) contain genetic information, mitochondrial DNA, prerequisite for mitochondrial functioning, particularly information required for mitochondrial electron transport. To understand nucleoid functioning, it is imperative to know its ultrastructure and dynamics in the context of the actual mitochondrial state. In this study, we document the internal structure, different positions of nucleoids inside the mitochondrial tube and their different morphology. The nucleoid cores appear in section as circular or slightly oval objects ranging from 50 to 100 nm in diameter. They are mainly located in the matrix between cristae inside the mitochondrial tube but they are also frequently found close to the inner mitochondrial surface. In tightly packed form, their interior exhibits sophisticated nucleoprotein regularity. The core surroundings form an electron-lucent thick layer which is probably partitioned into separate chambers. We suggest that the morphology of nucleoids mirrors the mode of energy production, glycolysis versus oxidative phosphorylation. The new high resolution transmission electron microscopy method enabled us to obtain morphological characteristics on yet unpublished level. PMID:27174900

  5. Opportunity's Surroundings After Sol 1820 Drive (Stereo)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    [figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11841 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11841

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009).

    This view combines images from the left-eye and right-eye sides of the navigation camera. It appears three-dimensional when viewed through red-blue glasses with the red lens on the left.

    The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches).

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock.

    This view is presented as a cylindrical-perspective projection with geometric seam correction.

  6. Opportunity's Surroundings on Sol 1798 (Stereo)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    [figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11850 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11850

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this stereo 180-degree view of the rover's surroundings during the 1,798th Martian day, or sol, of Opportunity's surface mission (Feb. 13, 2009). North is on top.

    This view combines images from the left-eye and right-eye sides of the navigation camera. It appears three-dimensional when viewed through red-blue glasses with the red lens on the left.

    The rover had driven 111 meters (364 feet) southward on the preceding sol. Tracks from that drive recede northward in this view. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches).

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

    This view is presented as a cylindrical-perspective projection with geometric seam correction.

  7. Opportunity's Surroundings on Sol 1687 (Stereo)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    [figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11739 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11739

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this stereo, 360-degree view of the rover's surroundings on the 1,687th Martian day, or sol, of its surface mission (Oct. 22, 2008). The view appears three-dimensional when viewed through red-blue glasses.

    Opportunity had driven 133 meters (436 feet) that sol, crossing sand ripples up to about 10 centimeters (4 inches) tall. The tracks visible in the foreground are in the east-northeast direction.

    Opportunity's position on Sol 1687 was about 300 meters southwest of Victoria Crater. The rover was beginning a long trek toward a much larger crater, Endeavour, about 12 kilometers (7 miles) to the southeast.

    This panorama combines right-eye and left-eye views presented as cylindrical-perspective projections with geometric seam correction.

  8. Opportunity's Surroundings on Sol 1818 (Stereo)

    NASA Technical Reports Server (NTRS)

    2009-01-01

    [figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11846 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11846

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,818th Martian day, or sol, of Opportunity's surface mission (March 5, 2009). South is at the center; north at both ends.

    This view combines images from the left-eye and right-eye sides of the navigation camera. It appears three-dimensional when viewed through red-blue glasses with the red lens on the left.

    The rover had driven 80.3 meters (263 feet) southward earlier on that sol. Tracks from the drive recede northward in this view.

    The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

    This view is presented as a cylindrical-perspective projection with geometric seam correction.

  9. Geographic Information Retrieval for Just Your Surroundings

    NASA Astrophysics Data System (ADS)

    Yasuda, Norihito; Toda, Hiroyuki

    Geographic information retrieval (GIR) is a new research area that aims at the retrieval of geographic-related documents based not only on keyword relevance but also on geographic relationships between the query and the geographic information in texts. It is natural for people to want information related to just their surroundings. Conventional GIR systems, however, have relatively poor granularity, such as city or province, because they use geographic information in restricted ways -- mostly just for filtering. To address this problem, we propose a geographic scoring method that considers extent implied by each geographic names appeared in texts to emphasize geographic names that focus specific areas, rather than broad geographic names. Furthermore, to improve robustness against errors in pre-processing such as geo-parsing and geo-coding, we also propose a noise elimination method based on clustering. Evaluation is conducted using standard TREC-style evaluation metrics including MAP, R-precision, and so on. The results show that our method outperforms two baseline approaches: full-text search and using the nearest point in the text.

  10. Construction of a BALB/c congenic mouse, C.C3H-Lpsd, that expresses the Lpsd allele: analysis of chromosome 4 markers surrounding the Lps gene.

    PubMed Central

    Vogel, S N; Wax, J S; Perera, P Y; Padlan, C; Potter, M; Mock, B A

    1994-01-01

    Development of a congenic BALB/c mouse strain that contains a segment of chromosome 4 including the Lpsd allele of the lipopolysaccharide (LPS)-hyporesponsive C3H/HeJ strain is presented. On the basis of LPS-induced spleen cell mitogenesis, macrophage tumor necrosis factor secretion, and tyrosine phosphorylation in vitro and lethality in galactosamine-sensitized mice in vivo, the C.C3H-Lpsd strain provides a model of LPS hyporesponsiveness that is comparable to that of the parental C3H/HeJ strain. Analysis of markers in this region indicates that length of the donor fragment is approximately 5.5 centimorgans. Thus, the C.C3H-Lpsd strain provides an important genetic tool for analysis of markers in this region and for examining functional effects of Lpsd expression on the BALB/c background. Images PMID:7927709

  11. Liability issues surrounding oil drilling mud sumps

    SciTech Connect

    Dillon, J.J.

    1994-04-01

    This presentation examines liability issues surrounding oil drilling mud sumps and discusses them in relation to two recent cases that arose in Ventura County, California. Following a brief history of regulatory interest in oil drilling mud and its common hazardous substances, various cause of action arising from oil drilling mud deposits are enumerated, followed by defenses to these causes of action. Section 8002 (m) of the Resource Conservation and Recovery Act is mentioned, as are constituents of oil and gas waste not inherent in petroleum and therefore not exempt from regulation under the petroleum exclusion in the Comprehensive Environmental Response, Compensation and Recovery Act. Key legal words such as hazardous substance, release, public and private nuisance, trespass, responsible parties, joint and several liability, negligence, and strict liability are explained. The effects on liability of knowledge of the deposits, duty to restore land to its original condition, consent to the deposit of oil drilling mud, and noncompliance and compliance with permit conditions are analyzed. The state-of-the-art defense and research to establish this defense are mentioned. The newly created cause of action for fear of increased risk of cancer is discussed. Issues on transfer of property where oil drilling mud has been deposited are explored, such as knowledge of prior owners being imputed to later owners, claims of fraudulent concealment, and as is' clauses. The effects on the oil and gas industry of the California Court of Appeals for the Second District rulings in Dolan v. Humacid-MacLeod and Stevens v. McQueen are speculated.

  12. Understanding Community Norms Surrounding Tobacco Sales

    PubMed Central

    McDaniel, Patricia A.; Malone, Ruth E.

    2014-01-01

    Background In the US, denormalizing tobacco use is key to tobacco control; less attention has been paid to denormalizing tobacco sales. However, some localities have placed limits on the number and type of retailers who may sell tobacco, and some retailers have abandoned tobacco sales voluntarily. Understanding community norms surrounding tobacco sales may help accelerate tobacco denormalization. Methods We conducted 15 focus groups with customers of California, New York, and Ohio retailers who had voluntarily discontinued tobacco sales to examine normative assumptions about where cigarettes should or should not be sold, voluntary decisions to discontinue tobacco sales, and government limits on such sales. Results Groups in all three states generally agreed that grocery stores that sold healthy products should not sell tobacco; California groups saw pharmacies similarly, while this was a minority opinion in the other two states. Convenience stores were regarded as a natural place to sell tobacco. In each state, it was regarded as normal and commendable for some stores to want to stop selling tobacco, although few participants could imagine convenience stores doing so. Views on government's role in setting limits on tobacco sales varied, with California and New York participants generally expressing support for restrictions, and Ohio participants expressing opposition. However, even those who expressed opposition did not approve of tobacco sales in all possible venues. Banning tobacco sales entirely was not yet normative. Conclusion Limiting the ubiquitous availability of tobacco sales is key to ending the tobacco epidemic. Some limits on tobacco sales appear to be normative from the perspective of community members; it may be possible to shift norms further by problematizing the ubiquitous presence of cigarettes and drawing connections to other products already subject to restrictions. PMID:25180772

  13. Overhead View of Area Surrounding Pathfinder

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Overhead view of the area surrounding the Pathfinder lander illustrating the Sojourner traverse. Red rectangles are rover positions at the end of sols 1-30. Locations of soil mechanics experiments, wheel abrasion experiments, and APXS measurements are shown. The A numbers refer to APXS measurements as discussed in the paper by Rieder et al. (p. 1770, Science Magazine, see image note). Coordinates are given in the LL frame.

    The photorealistic, interactive, three-dimensional virtual reality (VR) terrain models were created from IMP images using a software package developed for Pathfinder by C. Stoker et al. as a participating science project. By matching features in the left and right camera, an automated machine vision algorithm produced dense range maps of the nearfield, which were projected into a three-dimensional model as a connected polygonal mesh. Distance and angle measurements can be made on features viewed in the model using a mouse-driven three-dimensional cursor and a point-and-click interface. The VR model also incorporates graphical representations of the lander and rover and the sequence and spatial locations at which rover data were taken. As the rover moved, graphical models of the rover were added for each position that could be uniquely determined using stereo images of the rover taken by the IMP. Images taken by the rover were projected into the model as two-dimensional 'billboards' to show the proper perspective of these images.

    NOTE: original caption as published in Science Magazine

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).

  14. Microscopic Meteoritic Material Surrounding Meteorite Craters

    NASA Astrophysics Data System (ADS)

    Smith, T. R.; Hodge, P.

    1993-07-01

    Meteoritic impact-related particles around meteorite craters can have several forms: (1) ablation spherules formed from the melt layer during atmospheric entry; (2) fragments of meteoritic metal formed by the shattering of the meteorite on impact; (3) fragments of metal oxide with meteoritic Fe/Ni ratios; (4) glassy spherules made up of a mixture of target rock and meteoritic material, formed by condensation of impact vapor; and (5) fragments of vesicular material formed from the impact melt. We are investigating the nature of the particles collected from soil surrounding the following craters: Odessa (Texas), Kaalijarvi (Estonia), Boxhole, Dalgaranga, Henbury, Snelling, Veevers, and Wolfe Creek (all Australia). No impact-related particles have been identified in the Veevers or Snelling samples. The Odessa samples include both meteoritic fragments (type 3) and Fe/Ni spherules (type 1). The Henbury samples include particles of type 4 [1] and type 2. The Boxhole samples include particles of types 1 and 4 [2]. The Kaalijarvi particles, being studied cooperatively with Reet Tiimaa of the Institute of Gelogy of the Estonian Academy of Sciences, include particles of type 3 and 5. The type 3 particles from Kaalijarvi are primarily kamacite, with small amounts of taenite. They have oxidized, Ni-free surface layers, probably formed by weathering. The vesicular particles are primarily made of glass that has a bulk composition that indicates that they are about half meteorite and half target rock material. The glass suggests partial recrystallization, with dendritic patterns of slightly different composition. Inclusions of quartz grains also occur and the outer layer in some cases is pure iron oxide. Many of the bubbles have their inner walls laced with patterns of iron condensate, often dendritic and in some cases in the form of stars. References: [1] Hodge P. W. and Wright F. W. (1971) JGR, 76, 3880-3895. [2] Hodge P. W. and Wright F. W. (1973) Meteoritics, 8, 315-320.

  15. Analysis of particles produced during airbag deployment by scanning electron microscopy with energy dispersive x-ray spectroscopy and their deposition on surrounding surfaces: a mid-research summary

    NASA Astrophysics Data System (ADS)

    Wyatt, J. Matney

    2011-06-01

    Airbags can be encountered in forensic work when investigating a car crash and are typically constructed with primerlike material to begin the deployment apparatus. The mechanisms of airbag deployment can produce particles ideal for scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS) analysis. A recent study published by Berk studied airbags with vents and showed that it is possible for particles generated from the deployment of these airbags to deposit on surfaces in the vehicle as the airbags deflate.1 Another paper published by Berk reported particles similar in morphology and composition to primer gunshot residue (GSR) are produced by side impact airbags.2 This paper's aim will be to show mid-point results of a study still in progress in which non-vented airbags were analyzed to determine if they exhibited the same particle depositing features as their vented airbag counterparts. Further investigation in this study is being performed to find more airbags which produce primer gunshot residue-like particles containing lead, barium, and antimony from airbag deployment. To date, the study has resulted in (1) non-vented airbags exhibiting deposition of particles suitable for SEM/EDS analysis and (2) no gunshot residue-like particles being detected from the airbag residues studied thus far.

  16. Air quality interventions and spatial dynamics of air pollution in Delhi and its surroundings

    PubMed Central

    Kumar, Naresh; Foster, Andrew D.

    2012-01-01

    The paper examines the spatial distribution of air pollution in response to recent air quality regulations in Delhi, India. Air pollution was monitored at 113 sites spread across Delhi and its surrounding areas from July–December 2003. From the analysis of these data three important findings emerge. First, air pollution levels in Delhi and its surroundings were significantly higher than that recommended by the World Health Organization (WHO). Second, air quality regulations in the city adversely affected the air quality of the areas surrounding Delhi. Third, industries and trucks were identified as the major contributors of both fine and coarse particles. PMID:23105916

  17. Turbulent Mixing in the Ocean and Shelf Seas Surrounding Antarctica

    NASA Astrophysics Data System (ADS)

    Padman, L.

    2006-12-01

    Ocean turbulence and mixing data have been collected from the Southern Ocean and coastal seas surrounding Antarctica since the early 1990's. I summarize these observations, discuss their implications for parameterization of diapycnal mixing in southern seas, and identify regions and processes deserving of further study. Mixing data have been acquired from: the western Weddell Sea; Maud Rise in the eastern Weddell Sea; the Bellingshausen Sea continental shelf; the northwest Ross Sea; the shelf break and inner shelf near the Mertz Glacier Tongue; Drake Passage; the region surrounding the South Scotia Ridge; and locations near the Kerguelen Plateau and the adjacent Antarctic coastal zone. Vertical diffusivities estimated for these diverse regions span at least three orders of magnitude. The different regions exhibit a variety of primary mechanisms for mixing including shear-driven instabilities, nonlinear equation-of-state effects (cabbeling and thermobaricity), double diffusion, and boundary-layer stresses and buoyancy exchange. Energy sources include density flows, extreme surface forcing by cold coastal katabatic winds, tide-driven mixing in the benthic layer, and in the pycnocline due to locally strong baroclinic tides; downward propagation of wind-forced near-inertial waves, and flow interactions with large-scale topographic features. From this review I identify regions and processes for which we presently have little information on which to base mixing parameterizations, and suggest field and analysis activities to overcome these limitations in the representation of mixing in Southern Ocean and global models.

  18. Finite element analysis on stress distribution of maxillary implant-retained overdentures depending on the Bar attachment design and palatal coverage

    PubMed Central

    2016-01-01

    PURPOSE The purpose of this study was to determine the effect of anchorage systems and palatal coverage of denture base on load transfer in maxillary implant-retained overdenture. MATERIALS AND METHODS Maxillary implant-retained overdentures with 4 implants placed in the anterior region of edentulous maxilla were converted into a 3-D numerical model, and stress distribution patterns in implant supporting bone in the case of unilateral vertical loading on maxillary right first molar were compared with each other depending on various types of anchorage system and palatal coverage extent of denture base using three-dimensional finite element analysis. RESULTS In all experimental models, the highest stress was concentrated on the most distal implant and implant supporting bone on loaded side. The stress at the most distal implant-supporting bone was concentrated on the cortical bone. In all anchorage system without palatal coverage of denture base, higher stresses were concentrated on the most distal implant and implant supporting bone on loaded side. CONCLUSION It could be suggested that when making maxillary implant retained overdenture, using Hader bar instead of milled bar and full palatal coverage rather than partial palatal coverage are more beneficial in distributing the stress that is applied on implant supporting bone. PMID:27141251

  19. The symbolism and myth surrounding nurses' uniform.

    PubMed

    Richardson, M

    This article addresses nurses' uniform from the perspective of the symbolic, myth, legend and competing discourse. The analysis touches upon why nurses working with people who have learning disabilities discarded the nurses' uniform and why other nurses may consider doing so, particularly if suitable alternatives exist. The analysis draws from various areas of nursing practice, including the nursing of disabled people, elderly people and people with learning disabilities. Nurses' uniform is revealed as a totem of considerable potency such that to wear a uniform in just any setting or context has to be cautioned. The practicalities of protective clothing are addressed. A differentiation is drawn between uniform and protective clothing such that much of the undesirable symbolism associated with uniform may be discarded with a consequent enhancement of the image of the nurse. PMID:10222879

  20. Platelets surrounding primary tumor cells are related to chemoresistance.

    PubMed

    Ishikawa, Satoko; Miyashita, Tomoharu; Inokuchi, Masafumi; Hayashi, Hironori; Oyama, Katsunobu; Tajima, Hidehiro; Takamura, Hironori; Ninomiya, Itasu; Ahmed, A Karim; Harman, John W; Fushida, Sachio; Ohta, Tetsuo

    2016-08-01

    Platelets are crucial components of the tumor microenvironment that function to promote tumor progression and metastasis. In the circulation, the interaction between tumor cells and platelets increases invasiveness, protects tumor cells from shear stress and immune surveillance, and facilitates tumor cell extravasation to distant sites. However, the role and presence of platelets in the primary tumor have not been fully determined. Here, we investigated the presence of platelets around breast cancer primary tumor cells and the associations between these cells. We further investigated the associations among platelets, tumor cells, chemoresistance, and epithelial-mesenchymal transition (EMT). We retrospectively analyzed data from 74 patients with human epidermal growth factor receptor 2 (HER2)‑negative breast cancer who underwent biopsies before treatment and subsequent neo-adjuvant chemotherapy. In biopsy specimens, we evaluated the expression of platelet-specific markers and EMT markers using immunohistochemistry. The associations among the expression of platelet‑specific markers in biopsy specimens, EMT, response to neo‑adjuvant chemotherapy, and survival were analyzed. The presence of platelets was observed in 44 out of 74 (59%) primary breast cancer biopsy specimens. Platelet‑positive tumor cells showed EMT‑like morphological changes and EMT marker expression. Primary tumor cells associated with platelets were less responsive to neo‑adjuvant chemotherapy (pCR rate: 10 vs. 50%, respectively; p=0.0001). Platelets were an independent predictor of the response to chemotherapy upon multivariable analysis (p<0.0001). In conclusion, there was a significant association between platelets surrounding primary tumor cells in the biopsy specimens and the chemotherapeutic response in breast cancer. Platelets surrounding primary tumor cells may represent novel predictors of chemotherapeutic responses. PMID:27349611

  1. Impact of Port Fouad offshore gas project on surrounding environment

    SciTech Connect

    Osman, E.N.M.

    1996-11-01

    EIA study was undertaken to assess the impact of the proposed Port Fouad Gas Development Plant on the surrounding environment. An environmental inventory was undertaken to present the baseline data of the surrounding environment. The surrounding environment of the site can be classified as unpolluted and contains significant natural resources such as Ashtoum El-Gamil Protectorate and Lake Manzala in addition to nearby residential areas such as a touristic village to the east and El-Garabaa Village to the west. The effect of the released wastes on the surrounding environment was evaluated and assessed in accordance with the local- and intentional standard specifications for air and water quality.

  2. Free thermohaline convection in sediments surrounding a salt column

    NASA Astrophysics Data System (ADS)

    Evans, David G.; Nunn, Jeffrey A.

    1989-09-01

    Complex groundwater convection patterns are possible near salt domes because groundwater is subject to both lateral heat and salinity gradients. In order to assess the mechanisms responsible for driving convection near salt domes we use dimensional analysis and numerical simulations to investigate coupled heat and salt transport in homogeneous sediments surrounding a cylindrical salt column. The dimensional analysis does not require the Boussinesq assumption. The coupled heat, solute, and groundwater transport equations are controlled by three dimensionless parameters: the Rayleigh number, the Lewis number, and the buoyancy ratio. The buoyancy ratio is the ratio of salinity to temperature effects on groundwater density, and it directly affects the groundwater flow equation. A finite difference numerical multigridding algorithm is used to iteratively solve the coupled transport equations. The multigridding technique was about 3 times faster than a point-wise successive overrelaxation solution. Boundary conditions for the numerical simulations were adjusted to represent different contrasts in the thermal gradient between the salt and the overlying sediments. The contrast in thermal gradient is parameterized by the thermal conductivity ratio and is responsible for isotherms being elevated near the salt. The analysis suggests that a wide range of convective flow patterns are possible, with flow occurring either up or down along the salt flank. The sense of convection is dependent mainly on the value of the buoyancy ratio and how sharply isotherms are pulled up near the salt. These factors in turn depend on the regional salinity variation, the time since diapirism, and the thermal conductivity of water saturated sediments. While this analysis provides useful insight into the mechanisms driving free convection near salt domes, the assumptions about medium and fluid properties may limit the applicability of dimensional analysis in simulating flow in specific geologic

  3. Design of water molecule and its surrounding

    NASA Astrophysics Data System (ADS)

    Danylo, R. I.; Okhrimenko, B. A.; Yablochkova, K. S.

    2015-02-01

    Hydrogen bonds and their fluctuations are one of the factors that determine the unique properties of water [1]. Building models of formation and rupture of hydrogen bonds due to non-eigen vibrations of a molecule of water is to a large extent determined by the availability of accurate information on the geometric structure of the water molecule. Geometric parameters of the water molecule have been well studied for the gaseous state. This was aided by the possibility of an experimental study of the regularities in the rotational spectra of molecules. However, some questions about the geometry of the water molecule in the liquid state remain unanswered. For example, many sources state that the valence angle of the water molecule decreases during the transition into the liquid state [2]. Based on the experimental data of molecular vibration spectra in D2O and H2O molecules [3], the authors have estimated valence angle of water in the liquid state. Consequently, the value of the valence angle of water in liquid state was determined to be (89 +/-2)°. A question of determination of libration vibrations of water molecule, as well as the analysis of its consequent inversion doubling, based on the new information on the equilibrium angle of the water molecules in the liquid state, constitutes an interest and is discussed in the present paper.

  4. Reduced visual surround suppression in schizophrenia shown by measuring contrast detection thresholds

    PubMed Central

    Serrano-Pedraza, Ignacio; Romero-Ferreiro, Verónica; Read, Jenny C. A.; Diéguez-Risco, Teresa; Bagney, Alexandra; Caballero-González, Montserrat; Rodríguez-Torresano, Javier; Rodriguez-Jimenez, Roberto

    2014-01-01

    Visual perception in schizophrenia is attracting a broad interest given the deep knowledge that we have about the visual system in healthy populations. One example is the class of effects known collectively as visual surround suppression. For example, the visibility of a grating located in the visual periphery is impaired by the presence of a surrounding grating of the same spatial frequency and orientation. Previous studies have suggested abnormal visual surround suppression in patients with schizophrenia. Given that schizophrenia patients have cortical alterations including hypofunction of NMDA receptors and reduced concentration of GABA neurotransmitter, which affect lateral inhibitory connections, then they should be relatively better than controls at detecting visual stimuli that are usually suppressed. We tested this hypothesis by measuring contrast detection thresholds using a new stimulus configuration. We tested two groups: 21 schizophrenia patients and 24 healthy subjects. Thresholds were obtained using Bayesian staircases in a four-alternative forced-choice detection task where the target was a grating within a 3∘ Butterworth window that appeared in one of four possible positions at 5∘ eccentricity. We compared three conditions, (a) target with no-surround, (b) target embedded within a surrounding grating of 20∘ diameter and 25% contrast with same spatial frequency and orthogonal orientation, and (c) target embedded within a surrounding grating with parallel (same) orientation. Previous results with healthy populations have shown that contrast thresholds are lower for orthogonal and no-surround (NS) conditions than for parallel surround (PS). The log-ratios between parallel and NS thresholds are used as an index quantifying visual surround suppression. Patients performed poorly compared to controls in the NS and orthogonal-surround conditions. However, they performed as well as controls when the surround was parallel, resulting in significantly

  5. Mars Pathfinder Landing Site and Surroundings

    NASA Technical Reports Server (NTRS)

    2007-01-01

    of 3:35 p.m., and the scene is illuminated from the west with a solar incidence angle of 52 degrees, thus the sun was about 38 degrees above the horizon. At a solar longitude of 154.0 degrees, the season on Mars is northern summer.

    [figure removed for brevity, see original site] Landing Site Region This is a close-up of the area in the vicinity of the Pathfinder landing site. Major features are named. The white box outlines the area of the image, discussed next, where hardware is seen.

    [figure removed for brevity, see original site] Hardware on the Surface This image shows the Pathfinder lander on the surface. Zooming in, one can discern the ramps, science deck, and portions of the airbags on the Pathfinder lander. (See next image for closer view.) The back shell and parachute are to the south, and four features that may be portions of the heat shield are identified. Two of these were visible from Pathfinder. At the time of that mission, the nearest object was provisionally identified as the back shell. However, analysis of the HiRISE image and reinterpretation of Pathfinder images, plus an improved understanding of how hardware looks on the Martian surface based on ground-level and orbital images of the Mars Exploration Rover landing sites, indicate that the glint is bright enough that it may be insulating material from inside the heat shield. The back shell and parachute were out of sight behind a ridge from Pathfinder's ground view. One of the three bright features, identified as heat shield debris, was also identified during the Pathfinder mission.

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Annotated Version Unannotated Version Topographic Map of Landing Site Region Portions of the HiRISE image are overlaid onto color-coded topographic maps constructed by the U.S. Geological Survey from stereo images acquired by the Imager for Mars Pathfinder on the lander. The white feature

  6. Thermoelectric Performance Enhancement by Surrounding Crystalline Semiconductors with Metallic Nanoparticles

    NASA Technical Reports Server (NTRS)

    Kim, Hyun-Jung; King, Glen C.; Park, Yeonjoon; Lee, Kunik; Choi, Sang H.

    2011-01-01

    Direct conversion of thermal energy to electricity by thermoelectric (TE) devices may play a key role in future energy production and utilization. However, relatively poor performance of current TE materials has slowed development of new energy conversion applications. Recent reports have shown that the dimensionless Figure of Merit, ZT, for TE devices can be increased beyond the state-of-the-art level by nanoscale structuring of materials to reduce their thermal conductivity. New morphologically designed TE materials have been fabricated at the NASA Langley Research Center, and their characterization is underway. These newly designed materials are based on semiconductor crystal grains whose surfaces are surrounded by metallic nanoparticles. The nanoscale particles are used to tailor the thermal and electrical conduction properties for TE applications by altering the phonon and electron transport pathways. A sample of bismuth telluride decorated with metallic nanoparticles showed less thermal conductivity and twice the electrical conductivity at room temperature as compared to pure Bi2Te3. Apparently, electrons cross easily between semiconductor crystal grains via the intervening metallic nanoparticle bridges, but phonons are scattered at the interfacing gaps. Hence, if the interfacing gap is larger than the mean free path of the phonon, thermal energy transmission from one grain to others is reduced. Here we describe the design and analysis of these new materials that offer substantial improvements in thermoelectric performance.

  7. Satellite tumors surrounding primary pleomorphic adenomas of the parotid gland.

    PubMed

    Orita, Yorihisa; Hamaya, Kazuo; Miki, Kentaroh; Sugaya, Akiko; Hirai, Misato; Nakai, Kiyoko; Nose, Sohichiroh; Yoshino, Tadashi

    2010-05-01

    The occasional local recurrence of benign pleomorphic adenoma (PA) has generally been attributed to the vulnerability of the tumor capsule. Although some reports have also noted the presence of satellite tumors associated with PA recurrence, only few reports have focused on this issue. We paid special attention to the satellite lesions apart from the main tumors and discussed their frequency, origin, nature and the ways of treating them. A total of 108 specimens of primary parotid gland PA resected at the Okayama Saiseikai General Hospital from 1988 to 2008 were microscopically reviewed. Four (3.7%) patients displayed a main mass with satellite tumors in a single parotid gland. The immunohistochemical analysis of p53 and Ki-67 index showed no distinct difference between PAs with satellite tumors and those without. Satellite tumors surrounding the main mass of parotid PA is relatively rare. In most cases, such satellite tumors will arise from capsular perforation of the primary tumor cells. Preoperative evaluation to recognize the existence of satellite tumors would be important and capsular dissection should be discouraged. We could not find any evidence suggesting that primary PA with satellite tumors could be more biologically aggressive than those without. PMID:19898859

  8. Investigation of Thermal Equilibrium around an Accidental Event and Impact on Possibly Enclosed Surrounding Environment

    NASA Astrophysics Data System (ADS)

    Sarkar, Biswanath; Shah, Nitin; Choukekar, Ketan; Kapoor, Himanshu; Kumar, Uday; Das, Jotirmoy; Bhattacharaya, Ritendra; Vaghela, Hitensinh; Muralidhara, Srinivasa

    Complex and large cryogenic distribution systems are integral part of a fusion machine having superconducting magnets, cryopumps, etc. The various equipment of the cryogenic distribution system are interconnected via Cryogenic Transfer Lines (CTLs) to distribute cold helium to end users. During nominal operation of the fusion machine, helium inventory in CTLs could be in order of several tons. The cold helium present in CTLs could be released in surrounding volume due to accidental scenario. The present analysis, aims to estimate lowest temperature in the surrounding volume due to accidental scenario. The paper will describe simulation results and the test plan in a simulated condition.

  9. 14. INTERIOR VIEW OF FIREPLACE AND SURROUNDING WALL IN FIRST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. INTERIOR VIEW OF FIREPLACE AND SURROUNDING WALL IN FIRST FLOOR, NORTHWEST PARLOR, NORTH WALL, WITH SCALE (NOTE WALL STENCILING) - George W. Eckhart House, 810 Main Street, Wheeling, Ohio County, WV

  10. INTERIOR DETAIL, SOUTHEAST CABINET FIREPLACE. WHILE THE SURROUND HAS BEEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR DETAIL, SOUTHEAST CABINET FIREPLACE. WHILE THE SURROUND HAS BEEN ALTERED, THE FIREBACK IS LIKELY ORIGINAL OR EARLY TO THE HOUSE - The Woodlands, 4000 Woodlands Avenue, Philadelphia, Philadelphia County, PA

  11. Interior view of shower room 216 with original marble surround ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior view of shower room 2-16 with original marble surround and double sash windows, facing east. - Marine Barracks, Panama Canal, Barracks Building, 100' North of Thatcher Highway, Balboa, Former Panama Canal Zone, CZ

  12. 17. SPRINGHOUSE, SOUTHWEST SIDE; NOTE BROKEN GRANITE FOUNDATION FROM SURROUNDING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. SPRINGHOUSE, SOUTHWEST SIDE; NOTE BROKEN GRANITE FOUNDATION FROM SURROUNDING HILLSIDES. - Hondius Water Line, 1.6 miles Northwest of Park headquarters building & 1 mile Northwest of Beaver Meadows entrance station, Estes Park, Larimer County, CO

  13. 42. DETAIL OF TRIPLE WINDOW ELEMENT WITH DECORATIVE BRICK SURROUND, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    42. DETAIL OF TRIPLE WINDOW ELEMENT WITH DECORATIVE BRICK SURROUND, ON EAST SIDE OF 1931 SECTION, TAKEN FROM THE EAST. - James Russell Lowell Elementary School, 4501 Crittenden Drive, Louisville, Jefferson County, KY

  14. Everett Weinreb, Photographer, April 1989 BOYD FARMSTEAD SURROUNDED BY STRAWBERRY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Everett Weinreb, Photographer, April 1989 BOYD FARMSTEAD SURROUNDED BY STRAWBERRY FIELDS, FROM VALENCIA ROAD, LOOKING NORTHEAST - Irvine Ranch Agricultural Headquarters, Boyd Tenant House, Southeast of Intersection of San Diego & Santa Ana Freeways, Irvine, Orange County, CA

  15. Glow phenomenon surrounding the vertical stabilizer and OMS pods

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This 35mm frame, photographed as the Space Shuttle Columbia was orbiting Earth during a 'night' pass, documents the glow phenomenon surrounding the vertical stabilizer and the Orbital Maneuvering System (OMS) pods of the spacecraft.

  16. Detail view of door surround, note bracket & ghost of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view of door surround, note bracket & ghost of (former) arched opening in the brickwork beside it - Leonard Mackall House, 1686 Thirty-Fourth Street, Northwest, Washington, District of Columbia, DC

  17. 6. BRIDGE OF CARRIER JFK SURROUNDED BY SCAFFOLDING FOR REHABILITATION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. BRIDGE OF CARRIER JFK SURROUNDED BY SCAFFOLDING FOR REHABILITATION UNDER SERVICE LIFE EXTENSION PROGRAM (SLEP). - Naval Base Philadelphia-Philadelphia Naval Shipyard, Dry Dock No. 5, League Island, Philadelphia, Philadelphia County, PA

  18. NIH Scientists Shed Light on Mystery Surrounding Hepatitis B Virus

    MedlinePlus

    ... Research 2013 January 2013 (historical) NIH Scientists Shed Light on Mystery Surrounding Hepatitis B Virus Discovery Is ... the University of Oxford, U.K., have shed light on a long-standing enigma about the structure ...

  19. Differentiation of cutaneous melanoma from surrounding skin using laser-induced breakdown spectroscopy

    PubMed Central

    Han, Jung Hyun; Moon, Youngmin; Lee, Jong Jin; Choi, Sujeong; Kim, Yong-Chul; Jeong, Sungho

    2015-01-01

    Laser-induced breakdown spectroscopy (LIBS) has the potential to be used as a surgical tool for simultaneous tissue ablation and elemental analysis of the ablated tissue. LIBS may be used to distinguish melanoma lesions from the surrounding dermis based on the quantitative difference of elements within melanoma lesions. Here, we measured the elements in homogenized pellets and real tissues from excised skin samples of melanoma-implanted mice. In addition, statistical analysis of LIBS spectra using principal component analysis and linear discriminant analysis was performed. Our results showed that this method had high detection sensitivity, highlighting the potential of this tool in clinical applications. PMID:26819817

  20. REACTOR CORE SURROUNDED BY BERYLLIUM MODERATOR. CAMERA LOOKS DOWN AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    REACTOR CORE SURROUNDED BY BERYLLIUM MODERATOR. CAMERA LOOKS DOWN AND TOWARD NORTH INTO LOWER GRID CASTING. HOLES OF VARIOUS SIZES ACCOMMODATE COOLANT WATER AND EXPERIMENTAL POSITIONS. INL NEGATIVE NO. 4197. Unknown Photographer, 2/11/1952 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  1. 10. View of Western Rail and Surrounding Area to the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. View of Western Rail and Surrounding Area to the West (Lakeside Road was named Roxbury Avenue on the original plat. It was renamed Lakeside Road when a portion of the plat was replatted on August 1, 1925) - North Bridge, Spanning Quarton Lake branch of River Rouge, Birmingham, Oakland County, MI

  2. 10. View of Western Rail and Surrounding Area to the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. View of Western Rail and Surrounding Area to the West (Lakeside Road was named Roxbury Avenue on the original plat. It was renamed Lakeside Road when a portion of the plat was replatted on August 1, 1925) - South Bridge, Spanning Quarton Lake branch of River Rouge, Birmingham, Oakland County, MI

  3. Challenges Surrounding the Education of Children with Chronic Diseases

    ERIC Educational Resources Information Center

    Gordon, Maria, Ed.

    2016-01-01

    While governing bodies have mandated that all students have the right to an education, with disabled students treated to the same rights and opportunities as non-disabled students, policymakers do not always agree on what all-inclusive education should look like. "Challenges Surrounding the Education of Children with Chronic Diseases"…

  4. Biomedical and Market Issues Surrounding the Advent of Biosimilars.

    PubMed

    Cline, Abigail; Turrentine, Jake E

    2016-09-01

    As the patents associated with the biologics are set to expire in the near future, a new type of therapy appears on the horizon, and it is quite similar to the biologics. This commentary examines the biomedical and market issues surrounding the advent of biosimilars. PMID:27329376

  5. Level area surrounding Facility 314 showing the planted ring that ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Level area surrounding Facility 314 showing the planted ring that contains the radial ground wires, note the ring beneath the antenna circles is cleared of vegetation and covered with gravel, view facing southwest - U.S. Naval Base, Pearl Harbor, Naval Radio Station, AF/FRD-10 Circularly Disposed Antenna Array, Wahiawa, Honolulu County, HI

  6. Spatial heterogeneity of inhibitory surrounds in the middle temporal visual area.

    PubMed Central

    Xiao, D K; Raiguel, S; Marcar, V; Koenderink, J; Orban, G A

    1995-01-01

    A recurrent theme in the organization of vertebrate visual cortex is that of receptive fields with an associated "silent" opponency component. In the middle temporal area (area MT), a cortical visual area involved in the analysis of retinal motion in primates, this opponency appears in the form of a region outside the classical receptive field (CRF) that in itself gives no response but suppresses responses to motion evoked within the CRF. This antagonistic motion surround has been described as very large and symmetrically arrayed around the CRF. On the basis of this view, the primary function of the surround has long been thought to consist of simple figure-ground segregation based on movement. We have made use of small stimulus patches to map the form and extent of the surround and find evidence that the surround inhibition of many MT cells is in fact confined to restricted regions on one side or on opposite sides of the CRF. Such regions endow MT cells with the ability to make local-to-local motion comparisons, capable of extracting more complex features from the visual environment, and as such, may be better viewed as intrinsic parts of the receptive field, rather than as separate entities responsible for local-to-global comparisons. Images Fig. 2 Fig. 3 PMID:7479984

  7. Comparison of single-standing or connected implants on stress distribution in bone of mandibular overdentures: a two-dimensional finite element analysis.

    PubMed

    Tabata, Lucas Fernando; Assunção, Wirley Gonçalves; Barão, Valentim Adelino Ricardo; Gomes, Erica Alves; Delben, Juliana Aparecida; de Sousa, Edson Antônio Capello; Rocha, Eduardo Passos

    2010-05-01

    This study aimed to compare the influence of single-standing or connected implants on stress distribution in bone of mandibular overdentures by means of two-dimensional finite element analysis. Two finite element models were designed using software (ANSYS) for 2 situations: bar-clip (BC) group-model of an edentulous mandible supporting an overdenture over 2 connected implants with BC system, and o'ring (OR) group-model of an edentulous mandible supporting an overdenture over 2 single-standing implants with OR abutments. Axial loads (100 N) were applied on either central (L1) or lateral (L2) regions of the models. Stress distribution was concentrated mostly in the cortical bone surrounding the implants. When comparing the groups, BC (L1, 52.0 MPa and L2, 74.2 MPa) showed lower first principal stress values on supporting tissue than OR (L1, 78.4 MPa and L2, 76.7 MPa). Connected implants with BC attachment were more favorable on stress distribution over peri-implant-supporting tissue for both loading conditions. PMID:20485031

  8. Nanoscale heat transfer and phase transformation surrounding intensely heated nanoparticles

    NASA Astrophysics Data System (ADS)

    Sasikumar, Kiran

    Over the last decade there has been significant ongoing research to use nanoparticles for hyperthermia-based destruction of cancer cells. In this regard, the investigation of highly non-equilibrium thermal systems created by ultrafast laser excitation is a particularly challenging and important aspect of nanoscale heat transfer. It has been observed experimentally that noble metal nanoparticles, illuminated by radiation at the plasmon resonance wavelength, can act as localized heat sources at nanometer-length scales. Achieving biological response by delivering heat via nanoscale heat sources has also been demonstrated. However, an understanding of the thermal transport at these scales and associated phase transformations is lacking. A striking observation made in several laser-heating experiments is that embedded metal nanoparticles heated to extreme temperatures may even melt without an associated boiling of the surrounding fluid. This unusual phase stability is not well understood and designing experiments to understand the physics of this phenomenon is a challenging task. In this thesis, we will resort to molecular dynamics (MD) simulations, which offer a powerful tool to investigate this phenomenon, without assumptions underlying continuum-level model formulations. We present the results from a series of steady state and transient non-equilibrium MD simulations performed on an intensely heated nanoparticle immersed in a model liquid. For small nanoparticles (1-10 nm in diameter) we observe a stable liquid phase near the nanoparticle surface, which can be at a temperature well above the boiling point. Furthermore, we report the existence of a critical nanoparticle size (4 nm in diameter) below which we do not observe formation of vapor even when local fluid temperatures exceed the critical temperature. Instead, we report the existence of a stable fluid region with a density much larger than that of the vapor phase. We explain this stability in terms of the

  9. Doubles counting of highly multiplying items in reflective surroundings

    SciTech Connect

    Croft, Stephen; Evans, Louise G; Schear, Melissa A; Tobin, Stephen J

    2010-11-18

    When a neutrons are counted from a spontaneously fissile multiplying item in a reflecting environment the temporal behavior of the correlated signal following neutron birth is complex. At early times the signal is dominated by prompt fission events coming from spontaneous fission bursts and also from prompt fast-neutron induced fission events. At later times neutrons 'returning' from the surroundings induce fission and give rise to an additional chain of correlated events. The prompt and returning components probe the fissile and fertile constituents of the item in different ways and it is potentially beneficial to exploit this fact. In this work we look at how the two components can be represented using a linear combination of two simple functions. Fitting of the composite function to the capture time distribution represents one way of quantifying the proportion of each contribution. Another approach however is to use a dual shift register analysis where after each triggering event two coincidence gates are opened, one close to the trigger that responds preferentially to the prompt dynamics and one later in time which is more sensitive to the returning neutron induced events. To decide on the best gate positions and gate widths and also to estimate the counting precision we can use the analytical fit to work out the necessary gate utilization factors which are required in both these calculations. In this work, we develop the approach. Illustrative examples are given using spent Low Enriched Uranium (LEU) Pressurized light Water Reactor (LWR) fuel assemblies submersed in borated water and counted in a ring of {sup 3}He gas-filled proportional counters. In this case the prompt component is dominated by {sup 244}Cm spontaneous fission and induced fast neutron fission in for example {sup 238}U while the returning low energy neutrons induce fission mainly in the fissile nuclides such as {sup 239}Pu, {sup 241}Pu and {sup 235}U. One requirement is to calculate the Random

  10. Physics and technology of vertical surrounding gate MOSFETs

    NASA Astrophysics Data System (ADS)

    Auth, Christopher Patrick

    As semiconductor devices are scaled into the sub-0.1mum regime, lithographic issues become paramount in further scaling. Additionally, short-channel and poor subthreshold characteristics continue to plague planar MOSFETs. Double-gate or surrounding-gate MOSFETs fabricated on SOI substrates have shown promise in reducing the short channel problems and achieving a nearly ideal subthreshold slope. These devices are hampered by process complexity and floating body effects. They also remain dependent on lithographic techniques for scaling. The vertical, surrounding-gate MOSFET is starting to attract increasing attention for its ability to overcome these problems. Scaling of the channel length is no longer tied to lithography. They have a much smaller footprint than planar devices and the surrounding gate improves control of the gate over the channel potential reducing short channel effects. The vertical structure also decouples the channel length from the packing density. This work will present both simulation and experimental results which were used to examine the potential for the vertical MOSFET in deep submicron applications. The simulation results show an advantage of the cylindrical, surrounding-gate MOSFET over the double-gate structure for short channel length transistors. This improvement results from the increased proximity of the gate to the channel in the cylindrical structure. The benefit of this improved control is illustrated through derivation of a scaling theory for cylindrical MOSFETs. This scaling theory is used as a basis for comparing the cylindrical, surrounding-gate MOSFET to the double-gate MOSFET. Experimental results for vertical, surrounding-gate MOSFETs fabricated on pillars of silicon down to 300A thick are presented, illustrating the potential for fabricating the device at sub-0.1mum dimensions. The results illustrate the features of the device as it is scaled to small pillar thicknesses. The experimental results are compared to both

  11. Radio observations of supernova remnants and the surrounding molecular gas

    NASA Astrophysics Data System (ADS)

    Dubner, G.

    Supernova Remnants (SNRs) are believed to be the main source of Galactic cosmic rays (CR). The strong SNR shocks provide ideal acceleration sites for particles of at least ˜ 1014 eV/nucleon. Radio continuum studies of SNRs carried out with good sensitivity and high angular resolution convey information about three main aspects of the SNRs: morphology, polarization and spectrum. Based on this information it is possible to localize sites of higher compression and particle acceleration as well as the orientation and degree of order of the magnetic fields, and in some cases even its intensity. All this information, when complemented with the study of the distribution and kinematics of the surrounding interstellar gas, results in a very useful dataset to investigate the role of SNRs as cosmic ray accelerators. In this presentation, I analyze the radio observations of SNRs and surrounding molecular clouds, showing the contribution of these studies to the understanding of the role of SNRs as factories of CRs.

  12. Dynamics of two-component membranes surrounded by viscoelastic media.

    PubMed

    Komura, Shigeyuki; Yasuda, Kento; Okamoto, Ryuichi

    2015-11-01

    We discuss the dynamics of two-component fluid membranes which are surrounded by viscoelastic media. We assume that membrane-embedded proteins can diffuse laterally and induce a local membrane curvature. The mean squared displacement of a tagged membrane segment is obtained as a generalized Einstein relation. When the elasticity of the surrounding media obeys a power-law behavior in frequency, an anomalous diffusion of the membrane segment is predicted. We also consider the situation where the proteins generate active non-equilibrium forces. The generalized Einstein relation is further modified by an effective temperature that depends on the force dipole energy. The obtained generalized Einstein relations are useful for membrane microrheology experiments. PMID:26448393

  13. Greenstone belts: Their boundaries, surrounding rock terrains and interrelationships

    NASA Technical Reports Server (NTRS)

    Percival, J. A.; Card, K. D.

    1986-01-01

    Greenstone belts are an important part of the fragmented record of crustal evolution, representing samples of the magmatic activity that formed much of the Earth's crust. Most belts developed rapidly, in less than 100 Ma, leaving large gaps in the geological record. Surrounding terrains provide information on the context of greenstone belts. The effects of tectonic setting, structural geometry and evolution, associated plutonic activity and sedimentation are discussed.

  14. 14. VIEW, LOOKING SOUTHWEST, OF 'NAVY PIER' SURROUNDED BY BARGES, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. VIEW, LOOKING SOUTHWEST, OF 'NAVY PIER' SURROUNDED BY BARGES, AND SHIP LOADING GRAIN AT OUTSHORE HALF OF TERMINAL PIER UNDER CARGO MASTS AND GRAIN GALLERY D, July 7, 1922 (Original negative destroyed, print in Barge Canal Construction Photographs, Box 12, Series 501, Accession No.336-85) - New York Barge Canal, Gowanus Bay Terminal Pier, East of bulkhead supporting Columbia Street, Brooklyn, Kings County, NY

  15. Geomorphic Evolution of Sputnik Planum and Surrounding Terrain

    NASA Astrophysics Data System (ADS)

    Howard, A. D.; Moore, J. M.; White, O. L.; Umurhan, O. M.; Schenk, P.; Beyer, R. A.; McKinnon, W. B.; Singer, K. N.; Spencer, J. R.; Stern, A.; Weaver, H. A., Jr.; Young, L. A.; Ennico Smith, K.; Olkin, C.

    2015-12-01

    The informally-named Sputnik Planum is a vast expanse (about 835 km east-west and 1500 km north-south) of N2, CH4, and CO ices which appears craterless at current resolutions, but which gives evidence of both glacial and convective flow in the ices (Stern and the New Horizons Team, Science, 2015). This ice field is surrounded by uplands of varying morphology from hilly terrain to the northeast, plains of apparent ices interspersed with rough terrain to the east, and textured ice surrounding the mountainous terrain to the southwest. The morphology and composition of this bordering terrain will provide clues to the long-term evolution of Sputnik Planum as higher resolution visual and spectral imaging of this region are returned from the New Horizons spacecraft over the next few months. Interactions between Sputnik Planum and surrounding terrain may have involved glacial erosion and deposition. The geomorphic evolution of this region will be discussed in the context of newly-returned encounter data.

  16. HAM56 and CD68 antigen presenting cells surrounding a sarcoidal granulomatous tattoo

    PubMed Central

    Velez, Ana Maria Abreu; DeJoseph, Louis M.; Howard, Michael S.

    2011-01-01

    Context Tattoos are produced by introducing colorants of various compositions into the skin, either accidentally or for cosmetic purposes. Case Report: A 62-year-old male presented with a cosmetic tattoo and requested a total excision of the lesion. Dermatopathologic analysis of the excised tissue with hematoxylin and eosin examination, as well as immunohistochemistry was performed. H&E staining demonstrated classic histologic features of a tattoo. Utilizing immunohistochemistry, dermal histiocytic antigen presenting cells stained with HAM56 and CD68 antibodies; the staining was present surrounding the tattoo pigment. Conclusions We identified two macrophage markers (HAM56 and CD68) surrounding dermal tattoo pigment. A minimal dermal inflammatory immune was noted to the tattoo pigment. Moreover, the immune response and/or tolerance to tattoos is not well characterized. We suggest that tattoo materials and techniques could be utilized in therapeutic delivery for diseases such recessive dystrophic epidermolysis bullosa, potentially preventing immune rejection of gene therapy agents. PMID:22363088

  17. ORC4 surrounds extruded chromatin in female meiosis.

    PubMed

    Nguyen, Hieu; Ortega, Michael A; Ko, Myungjun; Marh, Joel; Ward, W Steven

    2015-05-01

    Six proteins, ORC1-6, make up the origin recognition complex (ORC) that initiates licensing of DNA replication origins. We have previously reported that subunit ORC2 is localized between the separating maternal chromosomes at anaphase II just after fertilization and is present in zygotic pronuclei at G1. Here, we found that ORC1, 3, and 5 all localize between the chromosomes at anaphase II, but could not be detected in zygotic G1. ORC6 localized to the periphery of the nucleoli at all zygotic stages. We identified an unexpected potential role for ORC4 in polar body formation. We found that in both female meiotic divisions, ORC4 surrounds the set of chromosomes, as a sphere-like structure, that will eventually be discarded in the polar bodies, but not the chromosomes that segregate into the oocyte. None of the other five ORC proteins are involved in this structure. In Zygotic G1, ORC4 surrounds the nuclei of the polar bodies, but was not detectable in the pronuclei. When the zygote entered mitosis ORC4 was only detected in the polar body. However, ORC4 appeared on both sets of separating chromosomes at telophase. At this point, the ORC4 that was in the polar body also migrated into the nuclei, suggesting that ORC4 or an associated protein is modified during the first embryonic cell cycle to allow it to bind DNA. Our results suggest that ORC4 may help identify the chromosomes that are destined to be expelled in the polar body, and may play a role in polar body extrusion. ORC4 surrounds the chromatin that will be extruded in the polar body in both female meiotic divisions, then makes a transition from the cytoplasm to the chromosomes at zygotic anaphase, suggesting multiple roles for this replication licensing protein. PMID:25502171

  18. ORC4 Surrounds Extruded Chromatin in Female Meiosis

    PubMed Central

    Nguyen, Hieu; Ortega, Michael A.; Ko, Myungjun; Marh, Joel; Ward, W. Steven

    2014-01-01

    Six proteins, ORC1-6, make up the origin recognition complex (ORC) that initiates licensing of DNA replication origins. We have previously reported that subunit ORC2 is localized between the separating maternal chromosomes at anaphase II just after fertilization and is present in zygotic pronuclei at G1. Here, we found that ORC1, 3, and 5 all localize between the chromosomes at anaphase II, but could not be detected in zygotic G1. ORC6 localized to the periphery of the nucleoli at all zygotic stages. We identified an unexpected potential role for ORC4 in polar body formation. We found that in both female meiotic divisions, ORC4 surrounds the set of chromosomes, as a sphere-like structure, that will eventually be discarded in the polar bodies, but not the chromosomes that segregate into the oocyte. None of the other five ORC proteins are involved in this structure. In Zygotic G1, ORC4 surrounds the nuclei of the polar bodies, but was not detectable in the pronuclei. When the zygote entered mitosis ORC4 was only detected in the polar body. However, ORC4 appeared on both sets of separating chromosomes at telophase. At this point, the ORC4 that was in the polar body also migrated into the nuclei, suggesting that ORC4 or an associated protein is modified during the first embryonic cell cycle to allow it to bind DNA. Our results suggest that ORC4 may help identify the chromosomes that are destined to be expelled in the polar body, and may play a role in polar body extrusion. extrusion. ORC4 surrounds the chromatin that will be extruded in the polar body in both female meiotic divisions, then makes a transition from the cytoplasm to the chromosomes at zygotic anaphase, suggesting multiple roles for this replication licensing protein. PMID:25502171

  19. Interaction of expanding abdominal aortic aneurysm with surrounding tissue: Retrospective CT image studies

    PubMed Central

    Kwon, Sebastian T.; Burek, William; Dupay, Alexander C.; Farsad, Mehdi; Baek, Seungik; Park, Eun-Ah; Lee, Whal

    2015-01-01

    Objectives Abdominal aortic aneurysms (AAA) that rupture have a high mortality rate. Rupture occurs when local mechanical stress exceeds the local mechanical strength of an AAA, so stress profiles such as those from finite element analysis (FEA) are useful. The role and effect of surrounding tissues, like the vertebral column, which have not been extensively studied, are examined in this paper. Methods Longitudinal CT scans from ten patients with AAAs were studied to see the effect of surrounding tissues on AAAs. Segmentation was performed to distinguish the AAA from other tissues and we studied how these surrounding tissues affected the shape and curvature of the AAA. Previously established methods by Veldenz et al. were used to split the AAA into 8 sections and examine the specific effects of surrounding tissues on these sections [1]. Three-dimensional models were created to better examine these effects over time. Registration was done in order to compare AAAs longitudinally. Results The vertebral column and osteophytes were observed to have been affecting the shape and the curvature of the AAA. Interaction with the spine caused focal flattening in certain areas of the AAA. In 16 of the 41 CT scans, the right posterior dorsal section (section 5), had the highest radius of curvature, which was by far the section that had the maximum radius for a specified CT scan. Evolution of the growing AAA showed increased flattening in this section when comparing the last CT scan to the first scan. Conclusion Surrounding tissues have a clear influence on the geometry of an AAA, which may in turn affect the stress profile of AAA. Incorporating these structures in FEA and G&R models will provide a better estimate of stress. Clinical Relevance Currently, size is the only variable considered when deciding whether to undergo elective surgery to repair AAA since it is an easy enough measure for clinicians to utilize. However, this may not be the best indicator of rupture risk

  20. Spirit's Surroundings on 'West Spur,' Sol 305 (Polar)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This 360-degree panorama shows the terrain surrounding NASA's Mars Exploration Rover Spirit as of the rover's 305th martian day, or sol, (Nov. 11, 2004). At that point, Spirit was climbing the 'West Spur' of the 'Columbia Hills.' The rover had just finished inspecting a rock called 'Lutefisk' and was heading uphill toward an area called 'Machu Picchu.' Spirit used its navigational camera to take the images combined into this mosaic. The rover's location when the images were taken is catalogued as the mission's site 89, position 205. The view is presented here as a polar projection with geometric seam correction.

  1. Spirit's Surroundings on 'West Spur,' Sol 305 (Vertical)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This 360-degree panorama shows the terrain surrounding NASA's Mars Exploration Rover Spirit as of the rover's 305th martian day, or sol, (Nov. 11, 2004). At that point, Spirit was climbing the 'West Spur' of the 'Columbia Hills.' The rover had just finished inspecting a rock called 'Lutefisk' and was heading uphill toward an area called 'Machu Picchu.' Spirit used its navigational camera to take the images combined into this mosaic. The rover's location when the images were taken is catalogued as the mission's site 89, position 205. The view is presented here as a vetical projection with geometric seam correction.

  2. The science and questions surrounding chronic traumatic encephalopathy.

    PubMed

    Ban, Vin Shen; Madden, Christopher J; Bailes, Julian E; Hunt Batjer, H; Lonser, Russell R

    2016-04-01

    Recently, the pathobiology, causes, associated factors, incidence and prevalence, and natural history of chronic traumatic encephalopathy (CTE) have been debated. Data from retrospective case series and high-profile media reports have fueled public fear and affected the medical community's understanding of the role of sports-related traumatic brain injury (TBI) in the development of CTE. There are a number of limitations posed by the current evidence that can lead to confusion within the public and scientific community. In this paper, the authors address common questions surrounding the science of CTE and propose future research directions. PMID:27032918

  3. EXPLICT CALULATIONS OF HOMOCLINIC TANGLES SURROUNDING MAGNETIC ISLANDS IN TOKAMAKS

    SciTech Connect

    ROEDER, R.K.W.; RAPOPORT, B.I.; EVANS, T.E.

    2002-06-01

    We present explicit calculations of the complicated geometric objects known as homoclinic tangles that surround magnetic islands in the Poincare mapping of a tokamak's magnetic field. These tangles are shown to exist generically in the magnetic field of all toroidal confinement systems. The geometry of these tangles provides an explanation for the stochasticity known to occur near the X-points of the Poincare mapping. Furthermore, the intersection of homoclinic tangles from different resonances provides an explicit mechanism for the non-diffusive transport of magnetic field lines between these resonance layers.

  4. High voltage bushing having weathershed and surrounding stress relief collar

    DOEpatents

    Cookson, Alan H.

    1981-01-01

    A high voltage electric bushing comprises a hollow elongated dielectric weathershed which encloses a high voltage conductor. A collar formed of high voltage dielectric material is positioned over the weathershed and is bonded thereto by an interface material which precludes moisture-like contaminants from entering between the bonded portions. The collar is substantially thicker than the adjacent weathershed which it surrounds, providing relief of the electric stresses which would otherwise appear on the outer surface of the weathershed. The collar may include a conductive ring or capacitive foil to further relieve electric stresses experienced by the bushing.

  5. Removal of oxyfluorfen from spiked soils using electrokinetic soil flushing with the surrounding arrangements of electrodes.

    PubMed

    Risco, C; Rubí-Juárez, H; Rodrigo, S; López-Vizcaíno, R; Saez, C; Cañizares, P; Barrera-Díaz, C; Navarro, V; Rodrigo, M A

    2016-07-15

    This work reports the results of a study in which the remediation of soil that undergoes an accidental discharge of oxyfluorfen is carried out by using electrokinetic soil flushing (EKSF). Two different electrode configurations were tested, consisting of several electrodes surrounding an electrode of different polarity (so-called 1A6C, one anode surrounded by six cathodes, and 1C6A, one cathode surrounded by six cathodes). A pilot plant scale was used (with a soil volume of 175dm(3)) to perform the studies. During the tests, different parameters were measured daily (flowrates, pH, electrical conductivity and herbicide concentration in different sampling positions). Furthermore, at the end of the test, a complete post-mortem analysis was carried out to obtain a 3-D map of the pollution, pH and electrical conductivity in the soil. The results demonstrate that electrode arrangement is a key factor for effective pollutant removal. In fact, the 1A6C configuration improves the removal rate by 41.3% versus the 27.0% obtained by the 1C6A configuration after a period of 35days. Finally, a bench mark comparison of this study of soil remediation polluted with 2,4-D allows for significant conclusions about the scale-up and full-scale application of this technology. PMID:27058128

  6. TRIGGERED STAR FORMATION SURROUNDING WOLF-RAYET STAR HD 211853

    SciTech Connect

    Liu Tie; Wu Yuefang; Zhang Huawei; Qin Shengli

    2012-05-20

    The environment surrounding Wolf-Rayet (W-R) star HD 211853 is studied in molecular, infrared, as well as radio, and H I emission. The molecular ring consists of well-separated cores, which have a volume density of 10{sup 3} cm{sup -3} and kinematic temperature {approx}20 K. Most of the cores are under gravitational collapse due to external pressure from the surrounding ionized gas. From the spectral energy distribution modeling toward the young stellar objects, the sequential star formation is revealed on a large scale in space spreading from the W-R star to the molecular ring. A small-scale sequential star formation is revealed toward core 'A', which harbors a very young star cluster. Triggered star formations are thus suggested. The presence of the photodissociation region, the fragmentation of the molecular ring, the collapse of the cores, and the large-scale sequential star formation indicate that the 'collect and collapse' process functions in this region. The star-forming activities in core 'A' seem to be affected by the 'radiation-driven implosion' process.

  7. Ionization nebulae surrounding supersoft X-ray sources

    NASA Technical Reports Server (NTRS)

    Rappaport, S.; Chiang, E.; Kallman, T.; Malina, R.

    1994-01-01

    In this work we carry out a theoretical investigation of a new type of astrophysical gaseous nebula, viz., ionized regions surrounding supersoft X-ray sources. Supersoft X-ray sources, many of which have characteristic luminosities of approximately 10(exp 37)-(10(exp 38) ergs/s and effective temperatures of approximately 4 x 10(exp 5) K, were first discovered with the Einstein Observatory. These sources have now been shown to constitute a distinct class of X-ray source and are being found in substantial numbers with ROSAT. We predict that these sources should be surrounded by regions of ionized hydrogen and helium with properties that are distinct from other astrophysical gaseous nebulae. We present caluations of the ionization and temperature structure of these ionization nebulae, as well as the expected optical line fluxes. The ionization profiles for both hydrogen and helium exhibit substantially more gradual transitions from the ionized to the unionized state than is the case for conventional H II regions. The calculated optical line intensitites are presented as absolute fluxes from sources in the Large Magellanic Cloud and as fractions of the central source luminosity. We find, in particular, that (O III) lambda 5008 and He II lambda 4686 are especially prominent in these ionization nebulae as compared to other astrophysical nebulae. We propose that searches for supersoft X-rays via their characteristic optical lines may reveal sources in regions where the soft X-rays are nearly completely absorbed by the interstellar medium.

  8. Surround inhibition in motor execution and motor imagery.

    PubMed

    Aoyama, Toshiyuki; Kaneko, Fuminari; Ohashi, Yukari; Nagata, Hiroshi

    2016-08-26

    Surround inhibition (SI) is a neural mechanism to focus neuronal activity and facilitate selective motor execution (ME). The aim of the present study was to investigate whether SI is also generated during motor imagery (MI). Furthermore, we investigated whether the extent of SI during MI depends on the strength of SI during ME and/or vividness of MI. The extent of SI was examined during MI and ME of index finger flexion. Transcranial magnetic stimulation was applied at rest, during initiation of the movement (phasic phase) and during tonic muscle contraction of the index finger flexors. Motor evoked potentials (MEPs) were recorded from a surround muscle, abductor digiti minimi (ADM) and a synergistic muscle, the first dorsal interosseous muscle. The amplitude of ADM MEP was reduced during the phasic phase, which indicates that SI occurred during ME. In seven of 14 subjects, SI was also observed during MI, although this effect was not significant. There was a moderate correlation between the extent of SI during ME and MI. Furthermore, good imagers who experienced vivid MI during the MI task showed stronger SI than poor imagers. These results indicate that common neural substrates involved in SI during ME are at least in part recruited during MI. In clinical situations, the therapeutic use of MI to generate vivid MI may be one of effective tool to develop the strength of SI, which facilitate selective execution of desired movements. PMID:27418120

  9. Expected size of shared haplotypes surrounding a common disease gene

    SciTech Connect

    Meerman, G.J. te; Meulen, M.A. van der; Sandkuijl, L.A.

    1994-09-01

    If two persons in a founder population share a rare disease, they may share genes involved in that disease Identical By Descent. We have calculated the probability of the size of the region IBD on either side of a shared common gene. Probabilities are plotted for various values of the meiotic count: the number of independent meioses connecting the persons. Even if this number is quite large, the shared area will, given the present density of markers, contain several markers. To be 95% certain that the area surrounding a gene can be delimited to less than 1 cM, approximately 500 meioses need to be observed. The many generations that are required before a gene is separated from its surrounding polymorphisms indicate that association between disease and marker alleles can be explained as IBD around a common gene. In founder populations apparantly unrelated affected persons will likely share disease genes introduced or mutated between 10 and 40 generations ago. Analyzing the overlap of haplotypes gives excellent opportunities to observe implicitly the many meioses required for genetic fine mapping.

  10. Effectively Communicating the Uncertainties Surrounding Ebola Virus Transmission.

    PubMed

    Kilianski, Andy; Evans, Nicholas G

    2015-10-01

    The current Ebola virus outbreak has highlighted the uncertainties surrounding many aspects of Ebola virus virology, including routes of transmission. The scientific community played a leading role during the outbreak-potentially, the largest of its kind-as many of the questions surrounding ebolaviruses have only been interrogated in the laboratory. Scientists provided an invaluable resource for clinicians, public health officials, policy makers, and the lay public in understanding the progress of Ebola virus disease and the continuing outbreak. Not all of the scientific communication, however, was accurate or effective. There were multiple instances of published articles during the height of the outbreak containing potentially misleading scientific language that spurred media overreaction and potentially jeopardized preparedness and policy decisions at critical points. Here, we use articles declaring the potential for airborne transmission of Ebola virus as a case study in the inaccurate reporting of basic science, and we provide recommendations for improving the communication about unknown aspects of disease during public health crises. PMID:26512988

  11. Assessing the impact of petrol stations on their immediate surroundings.

    PubMed

    Morales Terrés, Isabel M; Miñarro, Marta Doval; Ferradas, Enrique González; Caracena, Antonia Baeza; Rico, Jonathan Barberá

    2010-12-01

    This paper describes a novel methodology for evaluating the extent to which petrol stations affect their surroundings. The method is based on the fact that the ratio of the concentrations of aliphatic and aromatic hydrocarbon pollutants in the air of the petrol stations and their surroundings (basically determined by vapor emissions from unburned gasoline) differs from the ratio found in urban air, which is mainly influenced by traffic emissions. Bearing this in mind, the spatial limit of influence of petrol stations in any direction would be the first point, moving away from the station, where the ratio becomes equal to the urban background ratio. Application of the methodology involves multipoint measuring campaigns of the air at the studied petrol station and built-up area in general and processing the data with software capable of providing isoconcentration contours. The procedure should help local authorities in terms of land management, so that a "belt" can be established around petrol stations where housing or vulnerable populations and activities such as those in schools, hospitals and community centers should be restricted. PMID:20810207

  12. Effectively Communicating the Uncertainties Surrounding Ebola Virus Transmission

    PubMed Central

    Kilianski, Andy; Evans, Nicholas G.

    2015-01-01

    The current Ebola virus outbreak has highlighted the uncertainties surrounding many aspects of Ebola virus virology, including routes of transmission. The scientific community played a leading role during the outbreak—potentially, the largest of its kind—as many of the questions surrounding ebolaviruses have only been interrogated in the laboratory. Scientists provided an invaluable resource for clinicians, public health officials, policy makers, and the lay public in understanding the progress of Ebola virus disease and the continuing outbreak. Not all of the scientific communication, however, was accurate or effective. There were multiple instances of published articles during the height of the outbreak containing potentially misleading scientific language that spurred media overreaction and potentially jeopardized preparedness and policy decisions at critical points. Here, we use articles declaring the potential for airborne transmission of Ebola virus as a case study in the inaccurate reporting of basic science, and we provide recommendations for improving the communication about unknown aspects of disease during public health crises. PMID:26512988

  13. Linking student performance in Massachusetts elementary schools with the "greenness" of school surroundings using remote sensing.

    PubMed

    Wu, Chih-Da; McNeely, Eileen; Cedeño-Laurent, J G; Pan, Wen-Chi; Adamkiewicz, Gary; Dominici, Francesca; Lung, Shih-Chun Candice; Su, Huey-Jen; Spengler, John D

    2014-01-01

    Various studies have reported the physical and mental health benefits from exposure to "green" neighborhoods, such as proximity to neighborhoods with trees and vegetation. However, no studies have explicitly assessed the association between exposure to "green" surroundings and cognitive function in terms of student academic performance. This study investigated the association between the "greenness" of the area surrounding a Massachusetts public elementary school and the academic achievement of the school's student body based on standardized tests with an ecological setting. Researchers used the composite school-based performance scores generated by the Massachusetts Comprehensive Assessment System (MCAS) to measure the percentage of 3rd-grade students (the first year of standardized testing for 8-9 years-old children in public school), who scored "Above Proficient" (AP) in English and Mathematics tests (Note: Individual student scores are not publically available). The MCAS results are comparable year to year thanks to an equating process. Researchers included test results from 2006 through 2012 in 905 public schools and adjusted for differences between schools in the final analysis according to race, gender, English as a second language (proxy for ethnicity and language facility), parent income, student-teacher ratio, and school attendance. Surrounding greenness of each school was measured using satellite images converted into the Normalized Difference Vegetation Index (NDVI) in March, July and October of each year according to a 250-meter, 500-meter, 1,000-meter, and 2000-meter circular buffer around each school. Spatial Generalized Linear Mixed Models (GLMMs) estimated the impacts of surrounding greenness on school-based performance. Overall the study results supported a relationship between the "greenness" of the school area and the school-wide academic performance. Interestingly, the results showed a consistently positive significant association between the

  14. New Observations Deepen Mystery Surrounding Water Masers in Elliptical Galaxy

    NASA Astrophysics Data System (ADS)

    New observations with the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope have deepened the mystery surrounding water molecules in a galaxy 65 million light- years away. The water molecules are acting as natural masers -- amplifiers of microwave radio emissions -- and these cosmic masers within the galaxy NGC 1052 are raising difficult questions for astronomers trying to explain them. Results of the new observations, which pinpoint the location of water masers in NGC 1052, were announced today at the American Astronomical Society meeting in Toronto, Ontario. The researchers are: Jim Braatz of Harvard University in Cambridge, Massachusetts, Mark Claussen and Phil Diamond of the National Radio Astronomy Observatory in Socorro, New Mexico, Andrew Wilson of the University of Maryland in College Park, Maryland, and Christian Henkel of the Max Planck Institute fur Radioastronomie in Bonn, Germany. Water masers have been detected in several other galaxies. However, most galaxies containing water "megamasers" such as those in NGC 1052 are spiral galaxies. NGC 1052 is one of only two elliptical galaxies in which water megamasers have been detected. Because ellipticals tend to have much less gas and dust than spirals, the existence of the water masers in NGC 1052 is surprising by itself, though that galaxy does have more gas and dust than the typical elliptical. Located in the constellation Cetus, NGC 1052 also has an active nucleus, believed to be powered by the gravitational energy of a supermassive black hole at its core. The new VLBA observations produced an additional mystery. In other galaxies with water megamasers, the masers are believed to lie within a disk of molecules orbiting the galaxy's central black hole. This is the case, for example, in the now-famous galaxy NGC 4258, where the movement of the orbiting disk can be traced by measuring both the Doppler shift of radio emission from the masers and by tracking the motion of

  15. Impact Crater Particulates: Microscopic Meteoritic Material Surrounding Meteorite Craters

    NASA Astrophysics Data System (ADS)

    Smith, Toby Russell

    1995-01-01

    The influx of extraterrestrial matter onto the Earth is a ongoing process. Every year 40,000 metric tons of extraterrestrial matter is accreted by the Earth (Love 1993). A small fraction of this material arrives at Earth as objects large enough to survive the passage through atmosphere. Some of this material is completely melted as it passes through the atmosphere and arrives at the surface of the Earth as cosmic spherules. Cosmic spherules formed from metallic cosmic material undergoes changes in its elemental abundance as it passes through the atmosphere. The oxidation of the spherules results in the concentration of more refractory elements like Ni and Co into the metallic phase. Cosmic spherules are also formed by the passage of large meteorites through the atmosphere and their resulting impact onto the Earth. I found that the cosmic spherules from a wide variety of sources show a very similar trend in the elemental abundance patterns of their metallic phases. This trend is most obvious in the spherules recovered from the deep -sea and the spherules imbedded in impactite glass recovered from iron meteorite impact crater sites. The metallic spherules recovered from the soil surrounding impact craters do not show the high degree of elemental fractionation found in the deep-sea and impactite spherules. The composition of these spherules indicate that they are a mixture of meteoritic and target material. Metallic spherules are not the only meteoritic material to be found in the soil surrounding meteorite craters. I found that small fragments of the parent meteorite are an ubiquitous component of the soil surrounding the Odessa and Dalgaranga meteorite craters. These fragments occurred as small (most less than 400 mu m in size) heavily weathered fragments of meteoritic metal. The total calculated mass of these fragments is an order of magnitude larger than the mass of ponderable meteorites recovered from the site but 1 to 2 orders of magnitude smaller than the

  16. Solar Proton Transport within an ICRU Sphere Surrounded by a Complex Shield: Combinatorial Geometry

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Slaba, Tony C.; Badavi, Francis F.; Reddell, Brandon D.; Bahadori, Amir A.

    2015-01-01

    The 3DHZETRN code, with improved neutron and light ion (Z (is) less than 2) transport procedures, was recently developed and compared to Monte Carlo (MC) simulations using simplified spherical geometries. It was shown that 3DHZETRN agrees with the MC codes to the extent they agree with each other. In the present report, the 3DHZETRN code is extended to enable analysis in general combinatorial geometry. A more complex shielding structure with internal parts surrounding a tissue sphere is considered and compared against MC simulations. It is shown that even in the more complex geometry, 3DHZETRN agrees well with the MC codes and maintains a high degree of computational efficiency.

  17. Threshold voltage model of junctionless cylindrical surrounding gate MOSFETs including fringing field effects

    NASA Astrophysics Data System (ADS)

    Gupta, Santosh Kumar

    2015-12-01

    2D Analytical model of the body center potential (BCP) in short channel junctionless Cylindrical Surrounding Gate (JLCSG) MOSFETs is developed using evanescent mode analysis (EMA). This model also incorporates the gate bias dependent inner and outer fringing capacitances due to the gate-source/drain fringing fields. The developed model provides results in good agreement with simulated results for variations of different physical parameters of JLCSG MOSFET viz. gate length, channel radius, doping concentration, and oxide thickness. Using the BCP, an analytical model for the threshold voltage has been derived and validated against results obtained from 3D device simulator.

  18. Spirit's Surroundings on 'West Spur,' Sol 305 (3-D)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Figure 1

    [figure removed for brevity, see original site] Figure 2

    This 360-degree stereo panorama shows the terrain surrounding NASA's Mars Exploration Rover Spirit as of the rover's 305th martian day, or sol, (Nov. 11, 2004). At that point, Spirit was climbing the 'West Spur' of the 'Columbia Hills.' The rover had just finished inspecting a rock called 'Lutefisk' and was heading uphill toward an area called 'Machu Picchu.' Spirit used its navigational camera to take the images combined into this mosaic. The rover's location when the images were taken is catalogued as the mission's site 89, position 205. The stereo-anaglyph view presented here is a cylindrical projection with geometric seam correction.

    Figure 1 is the left-eye view of a stereo pair and Figure 2 is the right-eye view of a stereo pair.

  19. Wave rectification in plasma sheaths surrounding electric field antennas

    NASA Technical Reports Server (NTRS)

    Boehm, M. H.; Carlson, C. W.; Mcfadden, J. P.; Clemmons, J. H.; Ergun, R. E.; Mozer, F. S.

    1994-01-01

    Combined measurements of Langmuir or broadband whistler wave intensity and lower-frequency electric field waveforms, all at 10-microsecond time resolution, were made on several recent sounding rockets in the auroral ionosphere. It is found that Langmuir and whistler waves are partically rectified in the plasma sheaths surrounding the payload and the spheres used as antennas. This sheath rectification occurs whenever the high frequency (HF) potential across the sheath becomes of the same order as the electron temperature or higher, for wave frequencies near or above the ion plasma frequency. This rectification can introduce false low-frequency waves into measurements of electric field spectra when strong high-frequency waves are present. Second harmonic signals are also generated, although at much lower levels. The effect occurs in many different plasma conditions, primarily producing false waves at frequencies that are low enough for the antenna coupling to the plasma to be resistive.

  20. Percutaneous thermal ablation: how to protect the surrounding organs.

    PubMed

    Tsoumakidou, Georgia; Buy, Xavier; Garnon, Julien; Enescu, Julian; Gangi, Afshin

    2011-09-01

    A variety of thermal ablation techniques have been advocated for percutaneous tumor management. Although the above techniques are considered safe, they can be complicated with unintended thermal injury to the surrounding structures, with disastrous results. In the present article we report a number of different insulation techniques (hydrodissection, gas dissection and balloon interposition, warming/cooling systems) that can be applied. Emphasis is given to the procedure-related details, and we present the advantages and drawbacks of the insulation techniques. We also provide tips on avoiding painful skin burns when treating superficial lesions. Finally, we point out the interest of temperature monitoring and how it can be achieved (use of thermocouples, fiberoptic thermosensors, or direct magnetic resonance imaging temperature mapping). The above thermal insulation and temperature monitoring techniques can be applied alone or in combination. Familiarity with these techniques is essential to avoid major complications and to increase the indications of thermal ablation procedures. PMID:21767784

  1. New magnetic anomaly map of East Antarctica and surrounding regions

    USGS Publications Warehouse

    Golynsky, A.; Blankenship, D.; Chiappini, M.; Damaske, D.; Ferraccioli, F.; Finn, C.; Golynsky, D.; Goncharov, A.; Ishihara, T.; Ivanov, S.; Jokat, W.; Kim, H.R.; König, M.; Masolov, V.; Nogi, Y.; Sand, M.; Studing, M.; ADMAP Working Group

    2007-01-01

    community over East Antarctica and surrounding regions, significantly upgrade the Antarctic Digital Magnetic Anomaly Project (ADMAP) compilation and lead to substantial improvements in magnetic anomaly pattern recognition. New data have been matched in one inverse operation by minimizing the data differences for the areas of overlap. The aeromagnetic data show many previously unknown magnetic patterns, lineaments and trends, defining the spatial extent of Ferrar volcanics and plutonic Granite Harbour Intrusives in the Transantarctic Mountains and previously unknown tectonic trends of the East Antarctic craton. Regional aeromagnetic investigations have successfully delineated Early Paleozoic inherited crustal features along the flanks of the West Antarctic Rift System and the southern boundary of the Archean Ruker Terrane in the Prince Charles Mountains. Magnetic records along the East Antarctic continental margin provide new constraints on the breakup of Gondwana.

  2. High Speed Strain Measurements Surrounding Hydraulic Fracture in Brittle Hydrogel

    NASA Astrophysics Data System (ADS)

    Steinhardt, Will; Rubinstein, Shmuel

    2015-11-01

    Hydraulic fractures of oil and gas shales occur miles underground, below complex, layered rocks, making measurements of their dynamics, extent, or structure difficult to impossible. Rocks are heterogeneous at a wide range of length scales, and investigating how these non-uniformities affect the propagation and extent of fractures is vital to improving both the safety and efficiency of hydraulic fracturing operations. To study these effects we have developed a model system using brittle, heavily cross-linked hydrogels that we can fracture with fluids and observe with a fast camera. By embedding tracer particles within the gel and using laser sheet microscopy, we obtain three dimensional stress and strain maps of the zone surrounding a hydraulic fracture tip. Gels can also be set in layers or interfaces with tunable strengths or with designed heterogeneities, allowing us to understand the fundamental science of hydraulic fractures and investigate the dynamics of controllably complex materials.

  3. Geology of Sarawak deep water and its surroundings

    SciTech Connect

    Ismail, M.I.; Mohamad, A.M.; Ganesan, M.S.; Aziz, S.A. )

    1994-07-01

    A geological and geophysical investigation based primarily on seismic data indicates that four tectonostratigraphic zonations are recognizable in the Sarawak deep water and its surroundings. Zone A is a 7-8-km-thick Tertiary sedimentary basin in Sarawak deep water characterized by north-south-trending buried hills, extensional fault-bounded features, and local occurrences of compressional structures, and is separated from the northwest Sabah platform (zone B) by a major north-south-trending basin margin fault. This margin fault is distinct from the northwest-southeast transform fault known as Baram-Tinjar Line. The northwest Sabah platform, an attenuated continental crust that underwent late Mesozoic-Tertiary crystal stretching and rifting, is characterized by northeast-southwest-tending rift systems and generally up to 4 km-thick sedimentary cover. The leading edge of the northwest Sabah platform that was subducted beneath the northwest Borneo crust is marked by the Sabah trough (zone C). The western Sarawak deep water is occupied by a 13-km-thick, north-south-trending basin, the west Luconia delta province (zone D), demonstrating post mid-Miocene deltaic growth faults and toe-thrusts. Crustal offsets of the South China Sea Basin, north-south-trending basin margin fault between zones A and B, and extensional and compressional structures in zone A are evidence for north-south-directed transform motions leading to the development of the Sarawak deep-water Tertiary basin. Four main sedimentation phases describe the sedimentation history in Sarawak deep water and its surroundings. Oligocene-Miocene coastal plain sediments form the main hydrocarbon plays in the Sarawak deep water, and the numerous occurrences of amplitude anomalies clearly suggest a working hydrocarbon charge system.

  4. Optical coherence microscopy of mouse cortical vasculature surrounding implanted electrodes

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Lozzi, Andrea; Abliz, Erkinay; Greenbaum, Noah; Turner, Kevin P.; Pfefer, T. Joshua; Agrawal, Anant; Krauthamer, Victor; Welle, Cristin G.

    2014-03-01

    Optical coherence microscopy (OCM) provides real-time, in-vivo, three-dimensional, isotropic micron-resolution structural and functional characterization of tissue, cells, and other biological targets. Optical coherence angiography (OCA) also provides visualization and quantification of vascular flow via speckle-based or phase-resolved techniques. Performance assessment of neuroprosthetic systems, which allow direct thought control of limb prostheses, may be aided by OCA. In particular, there is a need to examine the underlying mechanisms of chronic functional degradation of implanted electrodes. Angiogenesis, capillary network remodeling, and changes in flow velocity are potential indicators of tissue changes that may be associated with waning electrode performance. The overall goal of this investigation is to quantify longitudinal changes in vascular morphology and capillary flow around neural electrodes chronically implanted in mice. We built a 1315-nm OCM system to image vessels in neocortical tissue in a cohort of mice. An optical window was implanted on the skull over the primary motor cortex above a penetrating shank-style microelectrode array. The mice were imaged bi-weekly to generate vascular maps of the region surrounding the implanted microelectrode array. Acute effects of window and electrode implantation included vessel dilation and profusion of vessels in the superficial layer of the cortex (0-200 μm). In deeper layers surrounding the electrode, no qualitative differences were seen in this early phase. These measurements establish a baseline vascular tissue response from the cortical window preparation and lay the ground work for future longitudinal studies to test the hypothesis that vascular changes will be associated with chronic electrode degradation.

  5. Levels, distributions and sources of veterinary antibiotics in the sediments of the Bohai Sea in China and surrounding estuaries.

    PubMed

    Liu, Xinghua; Zhang, Haibo; Li, Lianzhen; Fu, Chuancheng; Tu, Chen; Huang, Yujuan; Wu, Longhua; Tang, Jianhui; Luo, Yongming; Christie, Peter

    2016-08-15

    Veterinary antibiotics are emerging contaminants of concern. A total of 139 samples comprising 104 marine sediments and 35 estuarine sediments were collected from the Bohai Sea area and analyzed for seventeen antibiotics. The results reveal that the presence and concentration of antibiotics were generally higher in the estuaries than in the sea. The highest antibiotic concentration, 4695μgkg(-1) of oxytetracycline, occurred in the estuarine sediment from Ziya New River. Bohai Bay and Laizhou Bay and the surrounding estuaries had higher concentrations of antibiotics. However, low levels of antibiotics detected were detected in Liaodong Bay in contrast to the high concentrations present in the surrounding estuaries. Spatial heterogeneity and principal component analysis suggest a large impact of terrestrial sources of the antibiotics contaminating the Bohai Sea. Risk quotients indicate that current levels of norfloxacin and oxytetracycline might be potentially hazardous to sensitive biota both in the Bohai Sea and in its surrounding estuaries. PMID:27245555

  6. An organized start to implant-supported prosthesis

    PubMed Central

    Karthigeyan, Suma; Ali, Seyed Ashraff; Mohan, Kalarani; Deivanai, Mangala

    2013-01-01

    Various treatment options are available for rehabilitating the complete edentulous patients with implants. However, due consideration for the prosthesis is not given prior to implant surgery. This can result in implant being placed in locations that do not provide the best esthetic and functional result. Incorrect implant localization and angle are the primary cause of non-axial loading and may contribute to loss of Osseo-integration. For predictable outcome, the treatment should begin with visualizing the end result. A step-wise pre-implant surgery evaluation is necessary to achieve the objectives. This is a case report of a completely edentulous patient who was treated with fixed implant prosthesis following various steps in the pre-implant surgery evaluation. PMID:23853462

  7. Implant-supported overdentures: a longitudinal prospective study.

    PubMed

    Bergendal, T; Engquist, B

    1998-01-01

    The aim of this study was to evaluate the clinical function and long-term prognosis of overdentures retained by a small number of implants in the maxilla and mandible using one of two different attachment systems. Included in the study were all patients referred to specialty clinics in Jönköping and Linköping, Sweden, during the treatment period who needed an overdenture and could be provided with a minimum number of two bilaterally-placed implants. Excluded were patients with bone-grafted jaws, irradiated cancer patients, heavy bruxers, and patients who had lost a fixed prosthesis because of implant losses. The patients were randomly assigned to receive one retentive system, either a round 2-mm-diameter bar with clips or ball attachments (Nobel Biocare). Eighteen overdentures were placed in maxillae and 32 in mandibles, supported by a total of 115 Brånemark implants. Of the implants placed, 86.1% were continuously osseointegrated. The cumulative implant survival rates after 7 years of loading were 75.4% in the maxillae and 100% in the mandibles. There was no difference in implant survival rate between the attachment systems. Patients with implant losses were characterized by severely resorbed maxillary ridges and inferior bone quality, together with unfavorable loading circumstances such as short implants combined with long leverages. Complications and prosthetic adjustments were mostly resolved early and easily. PMID:9581412

  8. Highly Enriched uranium Metal Spheres Surrounded by Various Reflectors

    SciTech Connect

    Jessica Feener; J. Blair Briggs; Leland Montierth

    2007-05-01

    A series of experiments was performed at the Los Alamos critical assembly facility in the early 1950s to determine the critical mass of highly enriched uranium spheres surrounded by thin reflectors of various materials. The objective of these experiments was to obtain a precision graph of the critical mass of highly enriched uranium metal as a function of reflector thickness and to generate transport cross sections for the reflector material. Thirteen configurations are described and evaluated under ICSBEP identifier, HEU-MET-FAST-085; two with 1.98-inch-thick and 4.158-inch-thick copper reflectors, two with 2- and 4-inch-thick cast iron reflectors, one with a 1.945-inch-thick nickel reflector, two with 1.88- and 2.02-inch-thick nickel-copper-zinc alloy reflectors, one with a 1.81-inch-thick thorium reflector, two with 2-inch-thick and 4-inch-thick tungsten alloy reflectors, two with 2-inch-thick and 4.075-inch-thick zinc reflectors, and one with a 2-inch-thick tungsten alloy reflector surrounded by a 2-inch-thick cast iron reflector. All configurations were slightly subcritical with measured multiplications ranging from 20 to 162. Analyses were performed in which uncertainty associated with six different parameters was evaluated; namely, extrapolation to uranium critical mass, uranium density, 235U enrichment, reflector density, reflector thickness, and reflector impurities were considered. Uncertainty in cast-iron alloying elements was also considered when appropriate. In addition to the idealizations made by the experimenters, two simplifications were also made to the benchmark models that resulted in a small bias and additional uncertainty. First of all, since impurities in core and reflector materials are only estimated, they are not included in the benchmark models. Secondly, the room, support structure, and other possible surrounding equipment were not included in the model. Bias values that result from these two simplifications were determined and

  9. The water exchange between Chinchorro Bank and its surroundings

    NASA Astrophysics Data System (ADS)

    Candela, Julio; Ochoa, Jose Luis; Sheinbaum, Julio; Lopez, Manuel; Cornado, Cesar

    2015-04-01

    Chinchorro Bank is a relatively large (~500 km^ 2) atoll situated 33 km in front of the Yucatan Peninsula in the Caribbean coast of Mexico. Two years of continuous measurements of the subsurface pressure field inside and around Chinchorro Bank, along with currents and waves observed outside, suggest four major processes governing the water exchange of the Bank with its surroundings: 1) surface wave pumping of water into the Bank through its eastern edge, 2) the large scale circulation in the region that drives the sea level changes through geostrophy, 3) the tidal pumping with imposed cyclic flows into and out of the Bank and 4) the imposed drift by the wind. Waves impinging all along the eastern barrier reef induce water inflows (from overtopping the reef) and generate a pressure gradient that drives a drift from east to west throughout the Bank. This western drift can normally replenish the water over the Bank with a time scale of ~10 days. However, extreme wave events, lasting around 24 hours, can replenish the whole Bank's water in the order of day. The region's large scale circulation is dominated by the zonal Cayman Current impinging on the Yucatan Peninsula becoming the Yucatan Current as it turns northward. Variability in the strength and impacting latitude of this current causes sea level gradients within the Bank, i.e., a Yucatan Current increase of 1 m/s, over a period of a couple of weeks, sets up a zonal sea level gradient within that can replenish the whole Bank's water in a time scale of ~14 days. At such times, the large scale current around the Bank is at a maximum thus ensuring an effective removal and dispersal of the exported waters. The Bank has a micro-tidal regime with a semidiurnal amplitude of ~12 cm during spring tides and a diurnal of ~2 cm, these imply that the Bank is exchanging ~10% of its waters with its surroundings daily. However small, this tidal pumping is effective for the ventilation of the Banks' waters in ~10 days due to the

  10. AO 0235+164 and Surrounding Field: Surprising HST Results

    NASA Technical Reports Server (NTRS)

    Burbidge, E. M.; Beaver, E. A.; Cohen, Ross D.; Junkkarinen, V. T.; Lyons, R. W.

    1996-01-01

    Results obtained with the Hubble Space Telescope on the highly variable radio, x-ray, and gamma-ray emitting QSO (or BL Lac object) AO 0235 + 164 are presented and analyzed. WFPC2 images were obtained in 1994 June, when AO 0235 + 164 was bright (m approx. 17), and the results are described in Sec. 3. After subtraction of the PSF of the QSO, hereafter called AO following the nomenclature of Yanny et al. (1989), the companion object named A, 2 sec south of AO, is discovered not to be an elliptical galaxy as hypothesized earlier, but to be an AGN object, with a central UV-bright point-source nucleus and faint surrounding nebulosity extending to AO. The second companion object 1.3 sec east of AO discovered by Yanny et al. (1989) and named object Al, appears more like a normal spiral galaxy. We have measured the positions, luminosities, and colors of some 30 faint objects in the field around AO 0235 + 16; most are extended and may be star-forming galaxies in a loose group or cluster. Our most surprising result of the HST observations comes from FOS spectra obtained in 1995 July, discussed in Sec. 4. Because of a positioning error of the telescope and AO's faintness at that time (m approx. 20), object A was observed instead of the intended target AO. Serendipitously, we discovered A to have broad deep BALQSO-type absorptions of C IV, Si IV, N V shortward of broad emissions. A is thus ejecting high velocity, highly ionized gas into the surrounding IGM. We discuss in Sec. 5 the relationship of the objects in the central 10 sec X 1O sec region around AO, where redshifts z(sub e) = 0.94, z(sub a) = 0.524, 0.851 in AO, (sub e) = 0.524 and Z(sub BAL)=0.511 in A, are found. We hypothesize that some of the 30 faint objects in the 77 sec. x 77 sec. field may be part of a large star-forming region at z approx. 0.5, as suggested for a few objects by Yanny et al. (1989). The proximity of two highly active extragalactic objects, AO 0235+164 and its AGN companion A, is remarkable and

  11. Different bacterial communities in ectomycorrhizae and surrounding soil

    PubMed Central

    Vik, Unni; Logares, Ramiro; Blaalid, Rakel; Halvorsen, Rune; Carlsen, Tor; Bakke, Ingrid; Kolstø, Anne-Brit; Økstad, Ole Andreas; Kauserud, Håvard

    2013-01-01

    Several eukaryotic symbioses have shown to host a rich diversity of prokaryotes that interact with their hosts. Here, we study bacterial communities associated with ectomycorrhizal root systems of Bistorta vivipara compared to bacterial communities in bulk soil using pyrosequencing of 16S rRNA amplicons. A high richness of Operational Taxonomic Units (OTUs) was found in plant roots (3,571 OTUs) and surrounding soil (3,476 OTUs). The community composition differed markedly between these two environments. Actinobacteria, Armatimonadetes, Chloroflexi and OTUs unclassified at phylum level were significantly more abundant in plant roots than in soil. A large proportion of the OTUs, especially those in plant roots, presented low similarity to Sanger 16S rRNA reference sequences, suggesting novel bacterial diversity in ectomycorrhizae. Furthermore, the bacterial communities of the plant roots were spatially structured up to a distance of 60 cm, which may be explained by bacteria using fungal hyphae as a transport vector. The analyzed ectomycorrhizae presents a distinct microbiome, which likely influence the functioning of the plant-fungus symbiosis. PMID:24326907

  12. Multimode Surface Wave Tomography Of Asia And Surroundings

    NASA Astrophysics Data System (ADS)

    Lebedev, S.; van der Hilst, R. D.

    We construct a large-scale, high-resolution, 3-D model of the upper mantle beneath Asia, Australia, and surrounding oceans. Automated Multimode Inversion of surface waves (Lebedev and Nolet, 2000) is used to extract the waveform phase information from the regional S and fundamental-mode wavetrains and relate it to structural per- turbations in the Earth. Efficient selection of the wavetrains uncontaminated by scat- tered waves ensures high accuracy of the measurements. Full automation allows us to constrain the tomographic model using a large waveform data set of about twenty thousand vertical-component seismograms and to achieve lateral resolution of 400- 700 km, varying with the local ray-path coverage. The tectonically diverse region of study encompasses units ranging from stable Archean cratons and the oldest ocean floor on Earth to currently opening backarc basins. The western half of the Pacific ``Ring of Fire" dominates the cross-sections down to 150 km depth. At greater depths, a pattern of prominent high-velocity anoma- lies is created by the deep roots of Precambrian continental units (Yangtze, India, Siberia, and Kazakhstan), oceanic lithosphere subducted in the Western Pacific, and the Indian lithosphere descending beneath Tibet. High-velocity continental roots are present beneath some Precambrian units but absent beneath others, depending on their tectonic history. Laterally, the roots can reach beyond the present extent of the overly- ing Archean-Proterozoic crust by as much as a few hundred kilometers.

  13. Biologically Inspired Object Tracking Using Center-Surround Saliency Mechanisms.

    PubMed

    Mahadevan, Vijay; Vasconcelos, Nuno

    2013-03-01

    A biologically inspired discriminant object tracker is proposed. It is argued that discriminant tracking is a consequence of top-down tuning of the saliency mechanisms that guide the deployment of visual attention. The principle of discriminant saliency is then used to derive a tracker that implements a combination of center-surround saliency, a spatial spotlight of attention, and feature-based attention. In this framework, the tracking problem is formulated as one of continuous target-background classification, implemented in two stages. The first, or learning stage, combines a focus of attention (FoA) mechanism, and bottom-up saliency to identify a maximally discriminant set of features for target detection. The second, or detection stage, uses a feature-based attention mechanism and a target-tuned top-down discriminant saliency detector to detect the target. Overall, the tracker iterates between learning discriminant features from the target location in a video frame and detecting the location of the target in the next. The statistics of natural images are exploited to derive an implementation which is conceptually simple and computationally efficient. The saliency formulation is also shown to establish a unified framework for classifier design, target detection, automatic tracker initialization, and scale adaptation. Experimental results show that the proposed discriminant saliency tracker outperforms a number of state-of-the-art trackers in the literature. PMID:22529325

  14. Tuning structure and mobility of solvation shells surrounding tracer additives

    SciTech Connect

    Carmer, James; Jain, Avni; Bollinger, Jonathan A.; Truskett, Thomas M.; Swol, Frank van

    2015-03-28

    Molecular dynamics simulations and a stochastic Fokker-Planck equation based approach are used to illuminate how position-dependent solvent mobility near one or more tracer particle(s) is affected when tracer-solvent interactions are rationally modified to affect corresponding solvation structure. For tracers in a dense hard-sphere fluid, we compare two types of tracer-solvent interactions: (1) a hard-sphere-like interaction, and (2) a soft repulsion extending beyond the hard core designed via statistical mechanical theory to enhance tracer mobility at infinite dilution by suppressing coordination-shell structure [Carmer et al., Soft Matter 8, 4083–4089 (2012)]. For the latter case, we show that the mobility of surrounding solvent particles is also increased by addition of the soft repulsive interaction, which helps to rationalize the mechanism underlying the tracer’s enhanced diffusivity. However, if multiple tracer surfaces are in closer proximity (as at higher tracer concentrations), similar interactions that disrupt local solvation structure instead suppress the position-dependent solvent dynamics.

  15. Dilemmas surrounding passive euthanasia--a Malaysian perspective.

    PubMed

    Talib, Norchaya

    2005-09-01

    In western societies where the principle of autonomy is jealously guarded, perhaps active euthanasia is more often the focus of public concern and debates rather than any other forms of euthanasia. However due to the advance in technology and its corresponding ability in prolonging life, in Malaysia passive euthanasia presents more of a dilemma. For those concerned and involved with end of life decision-making, it is generally agreed that this is an area fraught with not only medical but legal and ethical issues. In Malaysia where the society is not homogenous but is multi-cultural and multi-religious, in addition to medical, legal and ethical issues, religious principles and cultural norms further impact and play significant roles in end of life decision-making. This paper seeks to identify the issues surrounding the practice of passive euthanasia in Malaysia. It will be shown that despite applicable legal provisions, current practice of the medical profession combined with religious and cultural values together affect decision-making which involves the withholding and/or withdrawing of life-saving treatment. PMID:16229394

  16. Tuning structure and mobility of solvation shells surrounding tracer additives.

    PubMed

    Carmer, James; Jain, Avni; Bollinger, Jonathan A; van Swol, Frank; Truskett, Thomas M

    2015-03-28

    Molecular dynamics simulations and a stochastic Fokker-Planck equation based approach are used to illuminate how position-dependent solvent mobility near one or more tracer particle(s) is affected when tracer-solvent interactions are rationally modified to affect corresponding solvation structure. For tracers in a dense hard-sphere fluid, we compare two types of tracer-solvent interactions: (1) a hard-sphere-like interaction, and (2) a soft repulsion extending beyond the hard core designed via statistical mechanical theory to enhance tracer mobility at infinite dilution by suppressing coordination-shell structure [Carmer et al., Soft Matter 8, 4083-4089 (2012)]. For the latter case, we show that the mobility of surrounding solvent particles is also increased by addition of the soft repulsive interaction, which helps to rationalize the mechanism underlying the tracer's enhanced diffusivity. However, if multiple tracer surfaces are in closer proximity (as at higher tracer concentrations), similar interactions that disrupt local solvation structure instead suppress the position-dependent solvent dynamics. PMID:25833590

  17. Multilayer Patch Antenna Surrounded by a Metallic Wall

    NASA Technical Reports Server (NTRS)

    Zawadzki, Mark; Huang, John

    2003-01-01

    A multilayer patch antenna, similar to a Yagi antenna, surrounded by a metallic wall has been devised to satisfy requirements to fit within a specified size and shape and to generate a beam with a half-power angular width of <=40 deg. This antenna provides a gain of about 14 dB; in contrast, the gain of a typical single-patch antenna lies between 5 and 6 dB. This antenna can be considered an alternative to a two-dimensional array of patch antenna elements, or to a horn or helical antenna. Unlike a two-dimensional array of patches, this antenna can function without need for a power-division network (unless circular polarization is needed). The profile of this antenna is lower than that of a horn or a helical antenna designed for the same frequency. The primary disadvantage of this antenna, relative to a horn or a helical antenna, is that its footprint is slightly larger.

  18. Aeromagnetic map of Yucca Mountain and surrounding regions, southwest Nevada

    USGS Publications Warehouse

    Kane, Martin Francis; Bracken, Robert E.

    1983-01-01

    Magnetic anomalies over Yucca Mountain and surrounding areas are largely caused by variations in magnetic properties and shapes, including structural offsets, of the extensive volcanic units that underlie the region. In a few places the anomalies are caused by intrusions. Correlation between magnetic properties measured from rock samples and those derived from rock unit-magnetic anomaly associations is excellent. Anomaly characteristics, extensive magnetic gradients, and marked changes in the regional magnetic field can be coupled with the magnetic properties of the rock units to delineate structural boundaries. Three major boundaries are indicated by contrasts in regional magnetic expressions. Less extensive but more clearly indicated boundaries in the immediate vicinity of Yucca Mountain are interpreted from a distinctive pairing of northerly-trending linear positive and negative anomalies which are caused by vertical displacement in generally gently dipping volcanic beds. The displacement between beds is located approximately along the border line between the linear anomaly pairs. One series of pairs of more northeasterly trend lies over the general location of a change from moderately thick to very thick volcanic units that was interpreted from gravity data. Several low amplitude but distinctively shaped anomalies in areas underlain primarily by sedimentary strata indicate the presence of intrusions and faults.

  19. A nebula of gases from Io surrounding Jupiter.

    PubMed

    Krimigis, Stamatios M; Mitchell, Donald G; Hamilton, Douglas C; Dandouras, Jannis; Armstrong, Thomas P; Bolton, Scott J; Cheng, Andrew F; Gloeckler, George; Hsieh, K C; Keath, Edwin P; Krupp, Norbert; Lagg, Andreas; Lanzerotti, Louis J; Livi, Stefano; Mauk, Barry H; McEntire, Richard W; Roelof, Edmond C; Wilken, Berend; Williams, Donald J

    2002-02-28

    Several planetary missions have reported the presence of substantial numbers of energetic ions and electrons surrounding Jupiter; relativistic electrons are observable up to several astronomical units (au) from the planet. A population of energetic (>30[?]keV) neutral particles also has been reported, but the instrumentation was not able to determine the mass or charge state of the particles, which were subsequently labelled energetic neutral atoms. Although images showing the presence of the trace element sodium were obtained, the source and identity of the neutral atoms---and their overall significance relative to the loss of charged particles from Jupiter's magnetosphere---were unknown. Here we report the discovery by the Cassini spacecraft of a fast (>103[?]km[?]s-1) and hot magnetospheric neutral wind extending more than 0.5[?]au from Jupiter, and the presence of energetic neutral atoms (both hot and cold) that have been accelerated by the electric field in the solar wind. We suggest that these atoms originate in volcanic gases from Io, undergo significant evolution through various electromagnetic interactions, escape Jupiter's magnetosphere and then populate the environment around the planet. Thus a 'nebula' is created that extends outwards over hundreds of jovian radii. PMID:11875559

  20. Earthquake hypocenter relocation using double difference method in East Java and surrounding areas

    SciTech Connect

    C, Aprilia Puspita; Nugraha, Andri Dian; Puspito, Nanang T

    2015-04-24

    Determination of precise hypocenter location is very important in order to provide information about subsurface fault plane and for seismic hazard analysis. In this study, we have relocated hypocenter earthquakes in Eastern part of Java and surrounding areas from local earthquake data catalog compiled by Meteorological, Climatological, and Geophysical Agency of Indonesia (MCGA) in time period 2009-2012 by using the double-difference method. The results show that after relocation processes, there are significantly changes in position and orientation of earthquake hypocenter which is correlated with the geological setting in this region. We observed indication of double seismic zone at depths of 70-120 km within the subducting slab in south of eastern part of Java region. Our results will provide useful information for advance seismological studies and seismic hazard analysis in this study.

  1. Earthquake hypocenter relocation using double difference method in East Java and surrounding areas

    NASA Astrophysics Data System (ADS)

    C, Aprilia Puspita; Nugraha, Andri Dian; Puspito, Nanang T.

    2015-04-01

    Determination of precise hypocenter location is very important in order to provide information about subsurface fault plane and for seismic hazard analysis. In this study, we have relocated hypocenter earthquakes in Eastern part of Java and surrounding areas from local earthquake data catalog compiled by Meteorological, Climatological, and Geophysical Agency of Indonesia (MCGA) in time period 2009-2012 by using the double-difference method. The results show that after relocation processes, there are significantly changes in position and orientation of earthquake hypocenter which is correlated with the geological setting in this region. We observed indication of double seismic zone at depths of 70-120 km within the subducting slab in south of eastern part of Java region. Our results will provide useful information for advance seismological studies and seismic hazard analysis in this study.

  2. Prostaglandin E2 level in tissue surrounding aseptic failed total hips. Effects of materials.

    PubMed

    Sedel, L; Simeon, J; Meunier, A; Villette, J M; Launay, S M

    1992-01-01

    Production of inflammatory mediators (IM) by cells and specifically macrophages around loosened implants may be responsible for their loosening. Our hypothesis was that different materials give rise to different amounts of these IM. It is thought that alumina/alumina for total hip replacement (THR), which has been used for 15 years in our orthopedic department, may produce less IM than other systems. We initiated a clinical prospective study to measure the level of prostaglandin E2 (PGE2) in tissue surrounding loosened prostheses to quantify PGE2 production regarding the types of material involved in the friction couple, i.e., alumina/alumina versus metal/polyethylene, and the type of fixation, i.e., cemented versus cementless. A total of 29 THR revisions were performed in 28 patients. Four implant groups were identified: alumina/alumina cemented, alumina/alumina cementless, metal/polyethylene cemented, and metal/polyethylene cementless. For each revision, tissues surrounding the failed implants were harvested and processed, and the PGE2 was measured in a blind manner using an immunoassay technique. As the measuring technique was difficult, at least three determinations for each sample were necessary. Some samples were excluded from the analysis for various reasons, for example, second or further revisions involving many different materials in the past, conjunction of metallic and alumina debris and samples taken from non-loosened components. Finally, 15 samples were considered adequate for inclusion in this study. Two groups were analyzed and compared: the alumina/alumina couple and the metal/polyethylene couple. Tissue surrounding the first group demonstrated a PGE2 level of 69 +/- 56 fmol/mg wet weight compared to 202 +/- 156 fmol/mg for the second.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1389776

  3. Searching for a gas cloud surrounding the WASP-18 planetary system

    NASA Astrophysics Data System (ADS)

    Fossati, L.; Ayres, T. R.; Haswell, C. A.; Jenkins, J. S.; Bisikalo, D.; Bohlender, D.; Flöer, L.; Kochukhov, O.

    2014-11-01

    Near-UV (NUV) Hubble Space Telescope (HST) observations of the extreme hot-Jupiter WASP-12b revealed the presence of diffuse exospheric gas extending beyond the planet's Roche lobe. Furthermore the NUV observations showed a complete lack of the normally bright core emission of the Mg ii h&k resonance lines, in agreement with the measured anomalously low stellar activity index (log R' HK ). Comparisons with other distant and inactive stars, and the analysis of radio and optical measurements of the intervening interstellar medium (ISM), led us to the conclusion that the system is surrounded by a circumstellar gas cloud, likely formed of material lost by the planet. Similar anomalous log R' HK index deficiencies might therefore signal the presence of translucent circumstellar gas around other stars hosting evaporating planets; we identified five such systems and WASP-18 is one of them. Both radio and optical observations of the region surrounding WASP-18 point towards a negligible ISM absorption along the WASP-18 line of sight. Excluding the unlikely possibility of an intrinsic anomalously low stellar activity, we conclude that the system is probably surrounded by a circumstellar gas cloud, presumably formed of material lost by the planet. Nevertheless only a far-UV spectrum of the star would provide a definite answer. Theoretical modelling suggests WASP-18b undergoes negligible mass loss, in contrast to the probable presence of a circumstellar gas cloud formed of material lost by the planet. The solution might be the presence either of an extra energy source driving mass loss (e.g., the reconnection of the stellar and planetary magnetic fields inside the planet atmosphere) or of an evaporating third body (e.g., moon).

  4. INSTABILITY OF MAGNETIZED IONIZATION FRONTS SURROUNDING H II REGIONS

    SciTech Connect

    Kim, Jeong-Gyu; Kim, Woong-Tae E-mail: wkim@astro.snu.ac.kr

    2014-12-20

    An ionization front (IF) surrounding an H II region is a sharp interface where a cold neutral gas makes the transition to a warm ionized phase by absorbing UV photons from central stars. We investigate the instability of a plane-parallel D-type IF threaded by parallel magnetic fields, by neglecting the effects of recombination within the ionized gas. We find that weak D-type IFs always have the post-IF magnetosonic Mach number M{sub M2}≤1. For such fronts, magnetic fields increase the maximum propagation speed of the IFs, while reducing the expansion factor α by a factor of 1 + 1/(2β{sub 1}) compared to the unmagnetized case, with β{sub 1} denoting the plasma beta in the pre-IF region. IFs become unstable to distortional perturbations owing to gas expansion across the fronts, exactly analogous to the Darrieus-Landau instability of ablation fronts in terrestrial flames. The growth rate of the IF instability is proportional linearly to the perturbation wavenumber, as well as the upstream flow speed, and approximately to α{sup 1/2}. The IF instability is stabilized by gas compressibility and becomes completely quenched when the front is D-critical. The instability is also stabilized by magnetic pressure when the perturbations propagate in the direction perpendicular to the fields. When the perturbations propagate in the direction parallel to the fields, on the other hand, it is magnetic tension that reduces the growth rate, completely suppressing the instability when M{sub M2}{sup 2}<2/(2β{sub 1}−1). When the front experiences an acceleration, the IF instability cooperates with the Rayleigh-Taylor instability to make the front more unstable.

  5. High-resolution mantle tomography of China and surrounding regions

    NASA Astrophysics Data System (ADS)

    Huang, Jinli; Zhao, Dapeng

    2006-09-01

    A high-resolution P wave tomographic model of the crust and mantle down to 1100 km depth under China and surrounding regions is determined by using about one million arrival times of P, pP, PP, and PcP waves from 19,361 earthquakes recorded by 1012 seismic stations. The subducting Pacific slab is imaged clearly as a high-velocity zone from the oceanic trenches down to about 600 km depth, and intermediate-depth and deep earthquakes are located within the slab. The Pacific slab becomes stagnant in the mantle transition zone under east China. The western edge of the stagnant slab is roughly coincident with a surface topographic boundary in east China. The active Changbai and Wudalianchi intraplate volcanoes in northeast China are underlain by significant slow anomalies in the upper mantle, above the stagnant Pacific slab. These results suggest that the active intraplate volcanoes in NE China are not hot spots but a kind of back-arc volcano associated with the deep subduction of the Pacific slab and its stagnancy in the transition zone. Under the Mariana arc, however, the Pacific slab penetrates directly down to the lower mantle. The active Tengchong volcano in southwest China is related to the eastward subduction of the Burma microplate. The subducting Indian and Philippine Sea plates are also imaged clearly. The Indian plate has subducted down to 200-300 km depth under the Tibetan Plateau with a horizontal moving distance of about 500 km. High-velocity anomalies are revealed in the upper mantle under the Tarim basin, Ordos, and Sichuan basin, which are three stable blocks in China.

  6. Giant Hα Nebula Surrounding the Starburst Merger NGC 6240

    NASA Astrophysics Data System (ADS)

    Yoshida, Michitoshi; Yagi, Masafumi; Ohyama, Youichi; Komiyama, Yutaka; Kashikawa, Nobunari; Tanaka, Hisashi; Okamura, Sadanori

    2016-03-01

    We revealed the detailed structure of a vastly extended Hα-emitting nebula (“Hα nebula”) surrounding the starburst/merging galaxy NGC 6240 by deep narrow-band imaging observations with the Subaru Suprime-Cam. The extent of the nebula is ˜90 kpc in diameter and the total Hα luminosity amounts to LHα ≈ 1.6 × 1042 erg s-1. The volume filling factor and the mass of the warm ionized gas are ˜10-4-10-5 and ˜5 × 108 M⊙, respectively. The nebula has a complicated structure, which includes numerous filaments, loops, bubbles, and knots. We found that there is a tight spatial correlation between the Hα nebula and the extended soft-X-ray-emitting gas, both in large and small scales. The overall morphology of the nebula is dominated by filamentary structures radially extending from the center of the galaxy. A large-scale bipolar bubble extends along the minor axis of the main stellar disk. The morphology strongly suggests that the nebula was formed by intense outflows—superwinds—driven by starbursts. We also found three bright knots embedded in a looped filament of ionized gas that show head-tail morphologies in both emission-line and continuum, suggesting close interactions between the outflows and star-forming regions. Based on the morphology and surface brightness distribution of the Hα nebula, we propose the scenario that three major episodes of starburst/superwind activities, which were initiated ˜102 Myr ago, formed the extended ionized gas nebula of NGC 6240. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  7. Paracrine tumor signaling induces transdifferentiation of surrounding fibroblasts.

    PubMed

    Heneberg, Petr

    2016-01-01

    Growth stimuli in cancer growth resemble those exhibited in wound healing. However, the process of nemosis is absent in cancer-associated fibroblasts (CAFs), which remain constitutively active. CAFs are present in almost all solid tumors but are most abundant in breast, prostate and pancreatic cancers. TGF-β1, TGF-β2, PDGF, IL-6, bFGF, reactive oxide species and protein kinase C are considered the key players in tumor-induced transdifferentiation of surrounding fibroblasts. Full-extent transdifferentiation was obtained only when the medium contained TGF-β1 or TGF-β2 (with or without other factors), whereas PDGF, bFGF or IL-6 (each alone) induced only partial transdifferentiation. Recent evidence suggests that the fibroblasts associated with primary cancers differ from those associated with metastases. The metastases-associated fibroblasts are converted by a metastasis-specific spectrum of factors. A large portion of paracrine tumor signaling is mediated by cancer cell-derived vesicles termed exosomes and microvesicles. The cancer cell-derived exosomes contain abundant and diverse proteomes and a number of signaling factors (TGF-ß1, TGF-ß2, IL-6, MMP2 and MMP9), particularly under hypoxic conditions. In contrast to the traditional view, the clonal expansion and selection of neoplastic cells should not be viewed outside the host body context. It is vital for a neoplastic cell to achieve the ability to re-program host body cells into CAFs and by this influence to modulate its microenvironment and receive positive feedback for growth and drug resistance. Neoplastic cells, which fail to develop such capacity, do not pass critical barriers in tumorigenesis and remain dormant and benign. PMID:26467073

  8. Trace Elements Speciation of Submicron Particulate Matter (PM1) Collected in the Surroundings of Power Plants

    PubMed Central

    Zajusz-Zubek, Elwira; Kaczmarek, Konrad; Mainka, Anna

    2015-01-01

    This study reports the concentrations of PM1 trace elements (As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Sb and Se) content in highly mobile (F1), mobile (F2), less mobile (F3) and not mobile (F4) fractions in samples that were collected in the surroundings of power plants in southern Poland. It also reports source identification by enrichment factors (EF) and a principal component analysis (PCA). There is limited availability of scientific data concerning the chemical composition of dust, including fractionation analyses of trace elements, in the surroundings of power plants. The present study offers important results in order to fill this data gap. The data collected in this study can be utilized to validate air quality models in this rapidly developing area. They are also crucial for comparisons with datasets from similar areas all over the world. Moreover, the identification of the bioavailability of selected carcinogenic and toxic elements in the future might be used as output data for potential biological and population research on risk assessment. This is important in the context of air pollution being hazardous to human health. PMID:26501310

  9. Different responses of different altitudes surrounding Taklimankan Desert to global climate change

    NASA Astrophysics Data System (ADS)

    Chongyi, E.; Yong, Wang; Taibao, Yang; Jiankang, Han; Hongchang, Hu; Fengmei, Yang

    2009-02-01

    Chongce Ice Cap (35°14'N, 81°07'E), located in the south margin of Taklimakan Desert, West Kunlun Mts. of China was sampled by coring in 1992, and this provides us with climate proxy of high altitudes (6,530 m). Through analyzing the weather observation stations surrounding Taklimakan Desert, the climate record of Hotan station was chosen to be the representative of low altitudes. Wavelet analysis were used to investigate the climatic variations of patterns, cycles and frequencies of different altitudes from 1954 to 1992, and different responses of different altitude surrounding Taklimakan Desert to global warming were recorded: (1) coherent decline of snow accumulation rate and dust deposition of high altitude recorded in Chongce ice core; (2) coherent increase of summer half-year precipitation and SAT of Hotan; (3) consistent variation tendency between dust deposit recorded in Chongce ice core and Hotan spring sandstorm days; (4) opposite variation tendency between Hotan precipitation and Chongce ice core snow accumulation rate and consistent cycles in general. By analyzing the mechanism of different responses, the predominant factors were determined of different altitudes: (1) at the low altitude, the vapor supply is predominant, and more vapor supplying means more precipitation; (2) at the high altitude, probably the population of dust aerosols which act as cloud ice nuclei in high altitude takes advantage over the vapor supply to affect the precipitation, and so the dust aerosol population reducing results in the wet deposition being reduced, thus the dust aerosol is the predominant factor.

  10. Trace Elements Speciation of Submicron Particulate Matter (PM1) Collected in the Surroundings of Power Plants.

    PubMed

    Zajusz-Zubek, Elwira; Kaczmarek, Konrad; Mainka, Anna

    2015-10-01

    This study reports the concentrations of PM1 trace elements (As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Sb and Se) content in highly mobile (F1), mobile (F2), less mobile (F3) and not mobile (F4) fractions in samples that were collected in the surroundings of power plants in southern Poland. It also reports source identification by enrichment factors (EF) and a principal component analysis (PCA). There is limited availability of scientific data concerning the chemical composition of dust, including fractionation analyses of trace elements, in the surroundings of power plants. The present study offers important results in order to fill this data gap. The data collected in this study can be utilized to validate air quality models in this rapidly developing area. They are also crucial for comparisons with datasets from similar areas all over the world. Moreover, the identification of the bioavailability of selected carcinogenic and toxic elements in the future might be used as output data for potential biological and population research on risk assessment. This is important in the context of air pollution being hazardous to human health. PMID:26501310

  11. The Tissue Implant Response Surrounding Subcutaneous TCP, HA, And ALCAP Bioceramics.

    PubMed

    Butler, K R; Benghuzzi, Hamed; Tucci, Michelle; Puckett, A D

    2015-01-01

    The objective of this investigation was to quantify and further elucidate the tissue-implant response in the fibrous tissue surrounding tricalcium phosphate (TCP), hydroxyapatite (HA), and aluminum calcium phosphate (ALCAP) implants when implanted subcutaneously. Sixteen animals in four experimental groups (n = 4/group) were implanted with one implant each: Group I (control, TCP), Group II (HA), and Group III (ALCAP). At 90 days post-implantation, the fibrous tissue surrounding the implants was harvested. Sections of stained fibrous tissue were evaluated for the presence of macrophages, fibrocytes, neutrophils, vascularity and thickness for all three groups using semi-automated quantitative methods. The analysis indicated Group III demonstrated a significantly higher number of neutrophils but fewer macrophages and blood vessels per high power field and had a substantially thinner fibrous tissue capsule thickness compared to Groups I and II (alpha=0.05). Group II elicited a greater response of fibroblasts compared to Groups I and III suggesting HA may provide a slightly higher degree of stability to the implant. In total, these findings suggest both TCP and HA behave similarly in vivo when compared to ALCAP and may be better choices for subcutaneous soft-tissue application compared to ALCAP. PMID:25996746

  12. Flow field stratigraphy surrounding Sekmet Mons Volcano, Kawelu Planitia, Venus

    NASA Astrophysics Data System (ADS)

    Zimbelman, James R.

    2003-05-01

    , they were most likely emplaced at modest effusion rates (~50 to 500 m3/s), and even with inflation the flows are likely <=15 m in thickness. Under these conditions all of the lobate plains surrounding Sekmet Mons could have been emplaced in ~14,000 to 1400 Earth years, assuming continuous effusion with only one source vent active at a time. At similar rates all of the lowland plains in the northern hemisphere of Venus could have been resurfaced by 15-m-thick flows through continuous single-vent effusion in ~1.4 million to ~140 thousand Earth years.

  13. Geomorphological Mapping of Sputnik Planum and Surrounding Terrain on Pluto

    NASA Astrophysics Data System (ADS)

    White, Oliver; Stern, Alan; Weaver, Hal; Olkin, Cathy; Ennico, Kimberly; Young, Leslie; Moore, Jeff

    2015-11-01

    The New Horizons flyby of Pluto in July 2015 has provided the first few close-up images of the Kuiper belt object, which reveal it to have a highly diverse range of terrains, implying a complex geological history. The highest resolution images that have yet been returned are seven lossy 400 m/pixel frames that cover the majority of the prominent Plutonian feature informally named Sputnik Planum (all feature names are currently informal), and its surroundings. This resolution is sufficient to allow detailed geomorphological mapping of this area to commence. Lossless versions of all 15 frames that make up the mosaic will be returned in September 2015, and the map presented at DPS will incorporate the total area covered by these frames.Sputnik Planum, with an area of ~650,000 km2, is notable for its smooth appearance and apparent total lack of impact craters at 400 m/pixel resolution. The Planum actually displays a wide variety of textures across its expanse, which includes smooth and pitted plains to the south, polygonal terrain at its center (the polygons can reach tens of kilometers in size and are bounded by troughs that sometimes feature central ridges), and, to the north, darker polygonal terrain displaying patterns indicative of glacial flow. Within these plains there exist several well-defined outcrops of a mottled, light/dark unit that reach from several to tens of kilometers across. Separating Sputnik Planum from the dark, cratered equatorial terrain of Cthulhu Regio on its south-western margin is a unit of chaotically arranged mountains (Hillary Montes); similar mountainous units exist on the south and western margins. The northern margin is bounded by rugged, hilly, cratered terrain (Cousteau Rupes) into which ice of Sputnik Planum appears to be intruding in places. Terrain of similar relief exists to the east, but is much brighter than that to the north. The southernmost extent of the mosaic features a unit of rough, undulating terrain (Pandemonium Dorsa

  14. Geomorphological Mapping of Sputnik Planum and Surrounding Terrain on Pluto

    NASA Astrophysics Data System (ADS)

    White, O. L.; Stern, S. A.; Weaver, H. A., Jr.; Olkin, C.; Ennico Smith, K.; Young, L. A.; Moore, J. M.; Cheng, A. F.

    2015-12-01

    The New Horizons flyby of Pluto in July 2015 has provided the first few close-up images of the Kuiper belt object, which reveal it to have a highly diverse range of terrains, implying a complex geological history. The highest resolution images that have yet been returned are seven lossy 400 m/pixel frames that cover the majority of the prominent Plutonian feature informally named Sputnik Planum (all feature names are currently informal), and its surroundings. This resolution is sufficient to allow detailed geomorphological mapping of this area to commence. Lossless versions of all 15 frames that make up the mosaic will be returned in September 2015, and the map presented at AGU will incorporate the total area covered by these frames. Sputnik Planum, with an area of ~650,000 km2, is notable for its smooth appearance and apparent total lack of impact craters at 400 m/pixel resolution. The Planum actually displays a wide variety of textures across its expanse, which includes smooth and pitted plains to the south, polygonal terrain at its center (the polygons can reach tens of kilometers in size and are bounded by troughs that sometimes feature central ridges), and, to the north, darker polygonal terrain displaying patterns indicative of glacial flow. Within these plains there exist several well-defined outcrops of a mottled, light/dark unit that reach from several to tens of kilometers across. Separating Sputnik Planum from the dark, cratered equatorial terrain of Cthulhu Regio on its south-western margin is a unit of chaotically arranged mountains; similar mountainous units exist on the south and western margins. The northern margin is bounded by rugged, hilly, cratered terrain into which ice of Sputnik Planum appears to be intruding in places. Terrain of similar relief exists to the east, but is much brighter than that to the north. The southernmost extent of the mosaic features a unit of rough, undulating terrain that displays very few impact craters at 400 m

  15. Facts and fiction surrounding the discovery of the venous valves.

    PubMed

    Scultetus, A H; Villavicencio, J L; Rich, N M

    2001-02-01

    Venous valves are delicate structures, the integrity of which is crucial for the normal function of the venous system. Their abnormalities lead to widespread disorders, ranging from chronic venous insufficiency to life-threatening thromboembolic phenomena. The discovery of the venous valves, however, has been the subject of hot controversy. Even though Fabricius ab Aquapendente is credited with the discovery by most historians, we demonstrate in this paper that other anatomists described them many years before Fabricius ab Aquapendente publicly demonstrated them in Padua in 1579. A thorough review of the historical literature surrounding the discovery of the venous valves was carried out from 1545 to the present under the supervision of the Medical History Department of our institution. Research was performed at the History of Medicine Division of the National Library of Medicine and through MEDLINE access to the medical literature. The Parisian Charles Estienne first mentioned the venous valves in his 1545 publication when he described "apophyses membranarum" in the veins of the liver. Lusitanus and Canano publicly demonstrated them in the azygos vein during cadaver dissections performed in Ferrera, Italy. The Parisian Jacques Sylvius described valves in the veins of the extremities in 1555. The work of these anatomists, however, could not achieve full recognition, because Andreas Vesalius, the leading anatomist at that time, was unable to confirm their findings and strongly denied the existence of venous valves. Vesalius's influence was so powerful that research on the subject was idle until 1579, when Fabricius ab Aquapendente "discovered" the venous valves. About the same time, the German Salomon Alberti published the first drawings of a venous valve (in 1585). William Harvey, a disciple of Fabricius ab Aquapendente, finally postulated the function of the venous valves, providing anatomical support for one of the greatest discoveries in medicine: the blood

  16. Highly Enriched Uranium Metal Cylinders Surrounded by Various Reflector Materials

    SciTech Connect

    Bernard Jones; J. Blair Briggs; Leland Monteirth

    2007-05-01

    A series of experiments was performed at Los Alamos Scientific Laboratory in 1958 to determine critical masses of cylinders of Oralloy (Oy) reflected by a number of materials. The experiments were all performed on the Comet Universal Critical Assembly Machine, and consisted of discs of highly enriched uranium (93.3 wt.% 235U) reflected by half-inch and one-inch-thick cylindrical shells of various reflector materials. The experiments were performed by members of Group N-2, particularly K. W. Gallup, G. E. Hansen, H. C. Paxton, and R. H. White. This experiment was intended to ascertain critical masses for criticality safety purposes, as well as to compare neutron transport cross sections to those obtained from danger coefficient measurements with the Topsy Oralloy-Tuballoy reflected and Godiva unreflected critical assemblies. The reflector materials examined in this series of experiments are as follows: magnesium, titanium, aluminum, graphite, mild steel, nickel, copper, cobalt, molybdenum, natural uranium, tungsten, beryllium, aluminum oxide, molybdenum carbide, and polythene (polyethylene). Also included are two special configurations of composite beryllium and iron reflectors. Analyses were performed in which uncertainty associated with six different parameters was evaluated; namely, extrapolation to the uranium critical mass, uranium density, 235U enrichment, reflector density, reflector thickness, and reflector impurities. In addition to the idealizations made by the experimenters (removal of the platen and diaphragm), two simplifications were also made to the benchmark models that resulted in a small bias and additional uncertainty. First of all, since impurities in core and reflector materials are only estimated, they are not included in the benchmark models. Secondly, the room, support structure, and other possible surrounding equipment were not included in the model. Bias values that result from these two simplifications were determined and associated

  17. Behavioural aspects surrounding medicine purchases from pharmacies in Australia

    PubMed Central

    Emmerton, Lynne

    2008-01-01

    Objective This study aimed to produce current data regarding behavioural aspects of non-prescription (over-the-counter) medicine purchases, in light of changes in the pharmaceutical market and increasing provision of professional services in pharmacies. Methods Data were collected in 15 community pharmacies in South-East Queensland, Australia, over 540 hours in five days in August, 2006. The method, previously validated, involved documentation of both observational and interview data. Fifteen trained researchers were stationed in a selected pharmacy each to unobtrusively observe all eligible sales of non-prescription medicines, and, where possible, interview the purchasers post-sale. Non-response was supplemented by observational data and recall by the salesperson. The data included details of the purchase and purchasing behaviour, while new questions addressed issues of topical importance, including customers’ privacy concerns. A selection of the analyses is reported here. Results In total, 3470 purchases were documented (135-479 per pharmacy), with customers of 67.5% of purchases (74.7% excluding an outlier pharmacy) participating in the survey. Customers averaged 1.2 non-prescription medicines per transaction. Two-thirds (67.2%) of customers were female, and 38.8% of the customers were aged 31-45 years. Analgesics and respiratory medicines accounted for two-thirds of the sales data (33.4% and 32.4%, respectively). Intended-brand purchases comprised 71% of purchases (2004/2824); in-store substitution then occurred in 8.8% of these cases, mainly following recommendations by pharmacy staff. Medicines intended for self-use comprised 62.9% of purchases (1752/2785). First-time purchases (30.8%, 799/2594) were more commonly influenced by pharmacy staff than by advertising. Conclusions This study used validated methods adapted to a changing marketplace, thus providing data that both confirm and add to knowledge surrounding medicine purchases. Despite the dynamics of

  18. Lagrangian study of the Panama Bight and surrounding regions

    NASA Astrophysics Data System (ADS)

    Chaigneau, Alexis; Abarca Del Rio, Rodrigo; Colas, FrançOis

    2006-09-01

    Near-surface circulation of the Panama Bight and surrounding regions [0-9°N; 73°W-90°W] was studied using satellite-tracked drifter trajectories from 1979-2004. This region encompasses three major currents showing typical velocities of ˜30 cm s-1: (1) the eastward North Equatorial Counter Current (NECC), (2) the near-circular Panama Bight Cyclonic Gyre (PBCG), and (3) the westward South Equatorial Current (SEC). We do not observe significant modification of the mean surface circulation during El Niño Southern Oscillation events, even if the SEC is slightly reinforced during relatively warm El Niño periods. At seasonal scales, the circulation is strongly controlled by the activity of the Panama wind-jet: in boreal winter, the currents are stronger and an anticyclonic cell is present west of the PBCG. This dipole leads to a strong ˜200 km wide southward current which then disappears during the rest of the year. In summer, the three major currents have reduced intensity by 30%-40%. Large-scale current vorticity shows that the upwelling associated with the PBCG is also 3-4 times stronger in winter than during summer months. The kinetic energy is largely dominated by eddy activity and its intensity is double in winter than during summer. Ageostrophic motions and eddy activity appear to have a substantial impact on the energy spatial distribution. In the NECC and SEC regions, Lagrangian scales are anisotropic and zonally enhanced in the direction of the mean currents. The typical integral time and length scales of these regions are 2.5 days and 50-60 km in the zonal direction and 1.5 days and 25-30 km in the meridional direction. Lateral eddy diffusivity coefficients are on the order of 11-14 107 cm2 s-1 zonally and 5-6 107 cm2 s-1 meridionally. In contrast, in the PBCG region, the Lagrangian characteristics are isotropic with typical timescales of 1.7 days, space scales of 30 km and eddy diffusivity coefficients of 6 107 cm2 s-1 in both directions.

  19. HUBBLE FINDS THOUSANDS OF GASEOUS FRAGMENTS SURROUNDING DYING STAR

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Resembling a bizarre setting from a science fiction movie, dramatic images sent back by NASA's Hubble Space Telescope have surprised astronomers by uncovering thousands of gigantic tadpole-shaped objects surrounding a dying star. Dubbed 'cometary knots' because their glowing heads and gossamer tails superficially resemble comets, they are probably the result of a dying star's final outbursts. Though ground-based telescopic observations have hinted at such objects, they have not previously been seen in such abundance, say researchers. The knots were detected by Hubble astronomer C. Robert O'Dell and graduate student Kerry P. Handron of Rice University in Houston, Texas, while exploring the Helix nebula, a ring of glowing gases blown off the surface of a sunlike star late in its life. O'Dell expects the gaseous knots, which are each several billion miles across, will eventually dissipate and vanish into the cold emptiness of interstellar space. However, he speculates that if the objects contract to form permanent solid bodies, they may contribute to a fraction (less than ten percent) of the missing mass of our galaxy, simply because of their sheer abundance around a typical dying star. (This so-called dark matter is a known source of gravity that affects the motions of stars in the galaxy). The mysterious 'space pods' came into view as O'Dell used Hubble's Wide Field Planetary Camera 2 to survey the Helix nebula, located 450 light-years away in the constellation Aquarius and the closest planetary nebula to Earth -- so close that its angular size is almost half that of the full Moon. The most visible cometary knots all lie along the inner edge of the ring, at a distance of trillions of miles from the central star. Their comet-like tails, each stretching a hundred billion miles, form a radial pattern around the star like the spokes on a wagon wheel. Though previous ground-based observations show a spoke pattern in the Helix, and some structure, O'Dell emphasizes that

  20. Chandra Uncovers New Evidence For Event Horizons Surrounding Black Holes

    NASA Astrophysics Data System (ADS)

    2001-01-01

    SAN DIEGO -- Astronomers have used NASA's Chandra X-ray Observatory to study some of the darkest black holes yet observed. Their work strongly confirms the reality of the "event horizon," the one-way membrane around black holes predicted by Einstein's theory of relativity. The findings were presented today at the American Astronomical Society meeting by Drs. Michael Garcia, Jeffrey McClintock, Ramesh Narayan, and Stephen Murray of the Harvard-Smithsonian Center for Astrophysics and Dr. Paul Callanan of University College, Cork, Ireland. With results that fundamentally differ from earlier black hole studies, Garcia and his colleagues have shown that some recently discovered black holes are not only ultra-dense, but actually possess event horizons that "vacuum up" energy from their surroundings. "It is a bit odd to say we've discovered something by seeing almost nothing at all -- less than the smile of the Cheshire cat, so to speak," said Garcia, lead author on a paper submitted to the Astrophysical Journal, "but, in essence, this is what we have done." Using data from Chandra and previous X-ray satellites like ROSAT, the Chandra team studied a dozen "X-ray novas," so named because they occasionally erupt as brilliant X-ray sources then settle into decades of dormancy. The great outpouring of X rays is due to a stream of gas that is pulled from the surface of a Sun-like companion star onto a compact object, either a black hole or a neutron star. By comparing the energy output from the dormant X-ray novas, the team discovered that the sources with black holes emitted only one percent as much energy while dormant as did the X-ray novae with neutron stars. "The most straightforward explanation of these observations is that the black hole candidates we have studied have event horizons that swallow just about all of the energy that surrounds them," said Murray. "Indeed, one could even say that this work shows why black holes deserve to be called ‘black.’" "The event

  1. Effects of surround articulation on lightness depend on the spatial arrangement of the articulated region

    NASA Astrophysics Data System (ADS)

    Zemach, Iris K.; Rudd, Michael E.

    2007-07-01

    We investigated the effect of surround articulation on the perceived lightness of a target disk. Surround articulation was manipulated by varying either the number of wedges in a surround consisting of wedges of alternating luminance or the number of checks in a surround consisting of a radial checkerboard pattern. In most conditions, increased articulation caused incremental targets to appear lighter and decremental targets to appear darker. But increasing the surround articulation in a way that did not increase the number of target-coaligned edges in the display did not affect the target lightness. We propose that the effects of surround articulation depend on the relationship between the orientations and contrast polarities of the target edges and those of edges present within the surround.

  2. Laser-induced fluorescence and reflectance spectroscopy for the discrimination of basal cell carcinoma from the surrounding normal skin tissue.

    PubMed

    Drakaki, E; Kaselouris, E; Makropoulou, M; Serafetinides, A A; Tsenga, A; Stratigos, A J; Katsambas, A D; Antoniou, C

    2009-01-01

    The object of this study was to investigate whether laser-induced skin autofluorescence (LIF) and/or light reflectance spectra could provide a useful contrast between basal cell carcinoma (BCC) tissues and the surrounding healthy skin. Unstained human skin samples, excised from humans undergoing biopsy examination, were irradiated with a nitrogen laser (lambda = 337 nm) for excitation of autofluorescence and a tungsten halogen lamp for the reflectance measurements. The ex vivo spectroscopic results were correlated with the histopathology images to distinguish the areas of BCC from those of the surrounding health skin. A simple spectral analysis technique was also applied for better skin diagnosis. In conclusion, it seems that LIF and reflectance spectra could be used to differentiate neoplastic from normal skin tissue using an appropriate classification model analysis. PMID:19365155

  3. Electromagnetic effects on the biological tissue surrounding a transcutaneous transformer for an artificial anal sphincter system.

    PubMed

    Zan, Peng; Yang, Bang-hua; Shao, Yong; Yan, Guo-zheng; Liu, Hua

    2010-12-01

    This paper reports on the electromagnetic effects on the biological tissue surrounding a transcutaneous transformer for an artificial anal sphincter. The coupling coils and human tissues, including the skin, fat, muscle, liver, and blood, were considered. Specific absorption rate (SAR) and current density were analyzed by a finite-length solenoid model. First, SAR and current density as a function of frequency (10-10(7) Hz) for an emission current of 1.5 A were calculated under different tissue thickness. Then relations between SAR, current density, and five types of tissues under each frequency were deduced. As a result, both the SAR and current density were below the basic restrictions of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The results show that the analysis of these data is very important for developing the artificial anal sphincter system. PMID:21121071

  4. Detained and Dying: Ethical Issues Surrounding End-of-Life Care in Prison.

    PubMed

    Stensland, Meredith; Sanders, Sara

    2016-01-01

    Prisons are increasingly being called upon to provide end-of-life (EOL) care within the restrictive correctional environment. Several relatively recent phenomena have brought medical ethics to the forefront of prison EOL care-including aging behind bars, a paradigm shift in prison culture, the increasing rate of in-prison deaths, and the corresponding prison hospice movement. This article examines prominent ethical issues that emerge for prison personnel who are tasked with providing care to terminally ill offenders by presenting three offender composite characters that exemplify dying offenders and emergent ethical issues surrounding their care. Identification and critical analysis of these ethical issues demonstrate the need for strong commitment to ethical practice and highlights specific issues for prisons to examine in their own EOL care practice. PMID:27462955

  5. A matching approach to communicate through the plasma sheath surrounding a hypersonic vehicle

    SciTech Connect

    Gao, Xiaotian; Jiang, Binhao

    2015-06-21

    In order to overcome the communication blackout problem suffered by hypersonic vehicles, a matching approach has been proposed for the first time in this paper. It utilizes a double-positive (DPS) material layer surrounding a hypersonic vehicle antenna to match with the plasma sheath enclosing the vehicle. Analytical analysis and numerical results indicate a resonance between the matched layer and the plasma sheath will be formed to mitigate the blackout problem in some conditions. The calculated results present a perfect radiated performance of the antenna, when the match is exactly built between these two layers. The effects of the parameters of the plasma sheath have been researched by numerical methods. Based on these results, the proposed approach is easier to realize and more flexible to the varying radiated conditions in hypersonic flight comparing with other methods.

  6. The effect of a planetary surface penetrator on the soil column surrounding the impacting body

    NASA Technical Reports Server (NTRS)

    Blanchard, M. B.; Shade, H. D.

    1975-01-01

    A prototype penetrator instrument was impacted into a dry lake bed. Laboratory studies of the soil surrounding the penetrator revealed that the soil was contaminated by paint and metal from the penetrator's casing. Paint pigment rich in titanium and sulfur was found in the adjacent soil. The highly mobile paint pigment migrated onto viewing ports in the penetrator's exterior. Bulk analysis of the soil adjacent to the impactor showed a significant increase in both elements, as well as the presence of metal chips from the casing and nose cone. It is recommended that great care be taken in the use of coating materials and the metal alloys selected for the penetrator's exterior, or the accuracy of any experiment requiring an uncontaminated in situ sample may be adversely affected.

  7. Models of the nearest surrounding of ions in aqueous solutions of dysprosium chloride

    NASA Astrophysics Data System (ADS)

    Smirnov, P. R.; Kritskii, I. L.; Grechin, O. V.

    2016-02-01

    Structural organization models are developed using radial distribution functions obtained earlier via XRD analysis for aqueous solutions of dysprosium chloride over a wide range of concentrations under standard conditions. The optimum variants are selected by calculating the theoretical functions for each model and comparing how they agree with experimental functions. Quantitative characteristics of the nearest surrounding of Dy3+ and Cl- ions, e.g., coordination numbers, interparticle distances, and varieties of ion pairs, are established. It is shown that the average number of water molecules in the first coordination sphere of a cation falls from 8.5 to 6 as the concentration grows; the structure of the system over the range of concentrations is determined by noncontact ion associates.

  8. The controversy surrounding bone morphogenetic proteins in the spine: a review of current research.

    PubMed

    Hustedt, Joshua W; Blizzard, Daniel J

    2014-12-01

    Bone morphogenetic proteins have been in use in spinal surgery since 2002. These proteins are members of the TGF-beta superfamily and guide mesenchymal stem cells to differentiate into osteoblasts to form bone in targeted tissues. Since the first commercial BMP became available in 2002, a host of research has supported BMPs and they have been rapidly incorporated in spinal surgeries in the United States. However, recent controversy has arisen surrounding the ethical conduct of the research supporting the use of BMPs. Yale University Open Data Access (YODA) recently teamed up with Medtronic to offer a meta-analysis of the effectiveness of BMPs in spinal surgery. This review focuses on the history of BMPs and examines the YODA research to guide spine surgeons in their use of BMP in spinal surgery. PMID:25506287

  9. Ethical, Legal and Social Issues Surrounding Research on Genetic Contributions to Anti-Social Behavior

    PubMed Central

    Berryessa, Colleen M.; Martinez-Martin, Nicole A.; Allyse, Megan A.

    2013-01-01

    Scientific study of genetic contributions to chronic antisocial behavior has stemmed from many lines of research in recent years. Genetic research involving twin, family, and adoption studies have traditionally been used to compare the health and behavior outcomes of individuals who share the same environment or hereditary lineage; several of these studies have concluded that heredity plays some role in the formation of chronic antisocial behavior, including various forms of aggression and chronic norm-defiance. However, the ethical, social, and legal environment surrounding research on the biological contributions to antisocial behavior in the United States is contentious. Although there has been some discussion in the last few decades regarding the ethical, social, and legal concerns around this type of research within academic and policy circles, analysis and discussion of these concerns rarely appear together. This paper explores the main themes that interact to form the basis of much of the resistance to positing biological contributions to antisocial behavior. PMID:24319343

  10. Multivariate statistical analyses of groundwater surrounding Forty mile wash

    SciTech Connect

    Woocay, A.; Walton, J.C.

    2007-07-01

    Groundwater chemistry data from 211 sampling locations in the vicinity of Yucca Mountain, Nevada are analyzed using multivariate statistical methods in order to better understand groundwater chemical evolution, ascertain potential flow paths and determine hydrochemical facies. Correspondence analysis of the major ion chemistry is used to define relationships between and among major ions and sampling locations. A k-means cluster analysis is used to determine hydrochemical facies based on correspondence analysis dimensions. The derived dimensions and hydrochemical facies are presented as bi-plots and overlaid on a digital elevation model of the region giving a visual picture of potential interactions and flow paths. A distinct signature of the groundwater chemistry along the extended flow path of Fortymile Wash can be observed along with some potential interaction at possible fault lines near Highway I-95. The signature from Fortymile Wash is believed to represent the relict of water that infiltrated during past pluvial periods when the amount of runoff in the wash was significantly larger than during the current drier period. This hypothesis appears to be supported by hydrogen-2 and oxygen-18 data which indicate that younger groundwater is found in the upper part of the wash near Yucca Mountain and older groundwater is found in the lower region of the wash near Amargosa River. The range of the hydrogen-2 data corresponds to precipitation in a period of relatively cold climate and has a similar spatial signature to the oxygen-18 data. If the hypothesis that current groundwater chemistry primarily reflects past focused infiltration of surface runoff rather than regional groundwater migration is correct, then saturated zone transport from Yucca Mountain may be much slower than is currently anticipated. (authors)

  11. An Investigation of Air Quality Surrounding Lake Merritt in Oakland, California

    NASA Astrophysics Data System (ADS)

    Ararso, I.; Casino, N.; Chen, B.; Johnson, J.; Koerber, K. W.; Lau, S.; Truisi, V.; Yanez, M.; Yeung, A.; Unigarro, M.; Vue, G.; Garduno, L.; Cuff, K.

    2005-12-01

    Lake Merritt is a naturally occurring inlet from the San Francisco Bay that was converted into an urban lake near downtown Oakland in 1860. The Lake itself is located within the Lake Merritt Park and Wildlife Refuge, home to over 90 species of migrating waterfowl, as well as a variety of aquatic wildlife. Its close proximity to downtown, several busy roads, and two major highways makes Lake Merritt a popular destination that is easily accessible to Oakland residents, but also puts it at risk for impaired air quality due to automobile exhaust. In an effort to assess air quality near Lake Merritt, we measured percent oxygen and carbon dioxide (CO2) concentrations in ambient air. These two gases can be used to assess air quality because the significant build up of CO2, which primarily results from the incomplete combustion of personal automobile engines, can result in the reduction of oxygen to concentration levels that are hazardous to human and other life. During the Summer of 2005, air samples from over 90 different locations were collected and used to make these measurements. Measurements were made with PASCO data-loggers attached to sensors that use infrared detectors to measure the amount of energy absorbed by carbon dioxide and oxygen molecules. Results were statistically analyzed, mapped, and used to assess the overall quality of air surrounding the Lake. Preliminary analysis of oxygen data indicates that higher concentration levels occur near sections of the Lake that are furthest removed from major roads, as well as in areas that have significant amounts of vegetation. In fact, the highest value recorded in this study was measured in a sample obtained near a grove of trees in a portion of the park that has the most vegetation, and that is furthest removed from major roads. Air quality here is high primarily due to the absence of CO2 build up associated with automobile traffic. The lowest values recorded were measured in samples collected along a stretch of

  12. Numerical investigation of heating of a gold nanoparticle and the surrounding microenvironment by nanosecond laser pulses for nanomedicine applications.

    PubMed

    Sassaroli, E; Li, K C P; O'Neill, B E

    2009-09-21

    We have modeled, by finite element analysis, the process of heating of a spherical gold nanoparticle by nanosecond laser pulses and of heat transfer between the particle and the surrounding medium, with no mass transfer. In our analysis, we have included thermal conductivity changes, vapor formation, and changes of the dielectric properties as a function of temperature. We have shown that such changes significantly affect the temperature reached by the particle and surrounding microenvironment and therefore the thermal and dielectric properties of the medium need to be known for a correct determination of the temperature elevation. We have shown that for sufficiently low intensity and long pulses, it is possible to establish a quasi-steady temperature profile in the medium with no vapor formation. As the intensity is increased, a phase-change with vapor formation takes place around the gold nanoparticle. As phase-transition starts, an additional increase in the intensity does not significantly increase the temperature of the gold nanoparticle and surrounding environment. The temperature starts to rise again above a given intensity threshold which is particle and environment dependent. The aim of this study is to provide useful insights for the development of molecular targeting of gold nanoparticles for applications such as remote drug release of therapeutics and photothermal cancer therapy. PMID:19717888

  13. Decomposition Odour Profiling in the Air and Soil Surrounding Vertebrate Carrion

    PubMed Central

    2014-01-01

    Chemical profiling of decomposition odour is conducted in the environmental sciences to detect malodourous target sources in air, water or soil. More recently decomposition odour profiling has been employed in the forensic sciences to generate a profile of the volatile organic compounds (VOCs) produced by decomposed remains. The chemical profile of decomposition odour is still being debated with variations in the VOC profile attributed to the sample collection technique, method of chemical analysis, and environment in which decomposition occurred. To date, little consideration has been given to the partitioning of odour between different matrices and the impact this has on developing an accurate VOC profile. The purpose of this research was to investigate the decomposition odour profile surrounding vertebrate carrion to determine how VOCs partition between soil and air. Four pig carcasses (Sus scrofa domesticus L.) were placed on a soil surface to decompose naturally and their odour profile monitored over a period of two months. Corresponding control sites were also monitored to determine the VOC profile of the surrounding environment. Samples were collected from the soil below and the air (headspace) above the decomposed remains using sorbent tubes and analysed using gas chromatography-mass spectrometry. A total of 249 compounds were identified but only 58 compounds were common to both air and soil samples. This study has demonstrated that soil and air samples produce distinct subsets of VOCs that contribute to the overall decomposition odour. Sample collection from only one matrix will reduce the likelihood of detecting the complete spectrum of VOCs, which further confounds the issue of determining a complete and accurate decomposition odour profile. Confirmation of this profile will enhance the performance of cadaver-detection dogs that are tasked with detecting decomposition odour in both soil and air to locate victim remains. PMID:24740412

  14. Arsenic contamination and speciation in surrounding waters of three old cinnabar mines.

    PubMed

    Larios, Raquel; Fernández-Martínez, Rodolfo; Silva, Verónica; Loredo, Jorge; Rucandio, Isabel

    2012-02-01

    The impact of arsenic pollution in waters from the surroundings of three abandoned Hg mines in Northern Spain, as well as reaching the Caudal River, was evaluated. For assessing the factors controlling arsenic release, an extensive study based on the physicochemical characterization and multivariate statistical analysis of waters upstream and downstream each mine site was performed. Waters downstream of the La Soterraña mine present the highest arsenic concentrations, up to 38.8 mg L(-1), coming mainly from the solubilisation of calcium, magnesium and strontium arsenates at a pH close to neutral. Although arsenic concentrations downstream of La Peña are markedly lower, these values remain too high, indicating that the encapsulation carried out in this spoil heap is insufficient. In addition, the high water flow in this point involves an extremely high input of arsenic to the surroundings (0.3 g s(-1)). Waters close to tailings from Los Rueldos suffer from acid mine drainage, provoking an important solubilisation of arsenic and heavy metals, a situation which is rapidly softened with distance. The study of arsenic speciation reveals the omnipresence of As(v) in waters from the three mines, whereas in La Peña low amounts of As(iii) were also detected. Different preservation methods for As speciation were compared, such as the addition of HCl, EDTA and the storage of samples without any additive, and no alteration of samples in any case up to nine months after the collection was observed. A study of seasonal variations of As and the main parameters affecting its concentration and speciation was completed throughout a year, showing no remarkable dependency with rainfall for any studied variable. PMID:22139034

  15. The selectivity of task-dependent attention varies with surrounding context.

    PubMed

    Kim, Yee-Joon; Verghese, Preeti

    2012-08-29

    Attention is thought to operate by enhancing the target of interest and suppressing the surroundings. We hypothesized that the spatial profile of attention depends on the surround's relationship to the target. Using high-density electroencephalographic measurements, we examined the spatial profile of attention to a grating target surrounded by an annular grating that was either coextensive with the target (unsegmented) or appeared segmented from it due to a gap or phase offset. We directly probed the spread of attention from the central target into the surround by flickering the surround and monitoring frequency-tagged steady-state visual-evoked potentials. Observers were required to detect a contrast increment that occurred only on the target. Successful detection of the increment required selecting the target and suppressing the surround, particularly when the target did not readily segment from the surround. The profile of attention was investigated in five visual regions of interest (ROIs) (V1, V4, V3A, lateral occipital complex, and human middle temporal area), mapped in a separate anatomical magnetic resonance imaging scan. We found that in most ROIs, attention to the target generated smaller responses from the surrounding annulus when it was contiguous compared with when it was clearly segmented. This result shows that the profile of attention depends on task demands and on surrounding context; attention is tightly focused when the target region needs to be isolated but loosely focused when the target region is clearly segmented. PMID:22933800

  16. Morphology and distribution of seamounts surrounding Easter Island

    USGS Publications Warehouse

    Rappaport, Y.; Naar, D.F.; Barton, C.C.; Liu, Z.-J.; Hey, R.N.

    1997-01-01

    We investigate the morphology and distribution of a seamount population on a section of seafloor influenced by both superfast seafloor spreading and hotspot volcanism. The population under investigation is part of a broad chain of seamounts extending eastward from the East Pacific Rise, near Easter Island. In order to define the morphological variability of the seamounts, basal shape, cross-sectional area, volume, flatness, and flank slope are plotted against height for 383 seamounts with heights greater than 200 m, based on bathymetry data collected by GLORI-B and SeaBeam 2000, during three cruises onboard the R/V Melville in the spring of 1993. Nearly complete swath mapping coverage of the seamounts is available for the analysis of size and shape distribution. We quantitatively describe the seamount population of this active region, in which seamounts cover ???27% of the seafloor, and account for ???4.2% of the total crustal volume. Over 50% of the total volume (61,000 km3) of seamounts used in this study is made up by the 14 largest seamounts, and the remaining volume is made up by the 369 smaller seamounts (>200 m in height). Our analysis indicates there are at least two seamount populations in the Easter Island-Salas y Gomez Island (25??-29??S, 113??-104??W) study area. One population of seamounts is composed of short seamounts (1200 m), shield-like, pointy cones (flatness ???1200 m) originate exclusively from a hotspot source, but only a portion of the smaller volcanoes (

  17. [Toxic fungi in Buenos Aires City and surroundings].

    PubMed

    Romano, Gonzalo M; Iannone, Leopoldo; Novas, María V; Carmarán, Cecilia; Romero, Andrea I; López, Silvia E; Lechner, Bernardo E

    2013-01-01

    In Facultad de Ciencias Exactas y Naturales,Universidad de Buenos Aires there is a service called Servicio de Identificación de Hongos Tóxicos, directed by researchers of the Program of Medicinal Plants and Fungi Involved in Biological Degradation (PROPLAME-PRHIDEB, CONICET) that assist hospitals and other health establishments, identifying the different samples of fungi and providing information about their toxicity, so that patients can receive the correct treatment. The objective of the present study was to analyze all the cases received from 1985 to 2012. This analysis permitted the confection of a table identifying the most common toxic species. The information gathered revealed that 47% of the patients were under 18 years of age and had eaten basidiomes; the remaining 53% were adults who insisted that they were able to distinguish edible from toxic mushrooms. Chlorophyllum molybdites turned out to be the main cause of fungal intoxication in Buenos Aires, which is commonly confused with Macrolepiota procera, an edible mushroom. In the second place Amanita phalloides was registered, an agaric known to cause severe symptoms after a long period of latency (6-10 hours), and which can lead to hepatic failure even requiring a transplant to prevent severe internal injuries or even death, is not early and correctly treated. PMID:24152394

  18. Metal accumulation in wild plants surrounding mining wastes.

    PubMed

    González, R Carrillo; González-Chávez, M C A

    2006-11-01

    Four sites were selected for collection of plants growing on polluted soil developed on tailings from Ag, Au, and Zn mines at the Zacatecas state in Mexico. Trace element concentrations varied between sites, the most polluted area was at El Bote mine near to Zacatecas city. The ranges of total concentration in soil were as follows: Cd 11-47, Ni 19-26, Pb 232-695, Mn 1132-2400, Cu 134-186 and Zn 116-827 mg kg(-1) air-dried soil weight. All soil samples had concentrations above typical values for non-polluted soils from the same soil types (Cd 0.6+/-0.3, Ni 52+/-4, Pb 41+/-3mg kg(-1)). However, for the majority of samples the DTPA-extractable element concentrations were less than 10% of the total. Some of the wild plants are potentially metal tolerant, because they were able to grow in highly polluted substrates. Plant metal analysis revealed that most species did not translocate metals to their aerial parts, therefore they behave as excluder plants. Polygonum aviculare accumulated Zn (9236 mg kg(-1)) at concentrations near to the criteria for hyperaccumulator plants. Jatropha dioica also accumulated high Zn (6249 mg kg(-1)) concentrations. PMID:16631286

  19. Issues Surrounding the Evaluation of Teacher Internship Programs

    NASA Astrophysics Data System (ADS)

    Barrett, D.

    2006-12-01

    Georgia Intern-Fellowships for Teachers (GIFT) is a collaborative effort designed to enhance mathematics and science experiences of Georgia teachers and their students through summer research internships for teachers. By offering business, industry, public science institute and research summer fellowships to teachers, GIFT provides educators with first-hand exposure to the skills and knowledge necessary for the preparation of our future workforce. Since 1991, GIFT has placed middle and high school math, science and technology teachers in over 1100 positions throughout the state. In these fellowships, teachers are involved in cutting edge scientific and engineering research, data analysis, curriculum development and real-world inquiry and problem solving, and create Action Plans to assist them in translating the experience into changed classroom practice. Since 2004, an increasing number of high school students have worked with their teachers in research laboratories. The GIFT program has an advisory board composed of university researchers, business and education leaders. The board members work in various subcommittees assisting the program with areas such as sponsor recruitment, evaluation and long term planning. The evaluation subcommittee has been actively involved in providing direction regarding the evaluation of the GIFT program's impact on teachers and their students. The program recently conducted a survey of its former participants. This presentation will discuss the results of the survey and the challenges associated with program evaluation of teacher internship programs.

  20. Interplanetary shocks and their interaction with surrounding environment

    NASA Astrophysics Data System (ADS)

    Safrankova, Jana; Nemecek, Zdenek; Prech, Lubomir; Lynnyk, Andrei; Jelinek, Karel

    Several studies have been devoted to the interaction of interplanetary (IP) shocks with both characteristic Earth's magnetospheric boundaries: the bow shock and magnetopause. Nonstationarity of this interaction requires multi-spacecraft observations with good spatial and temporal coverages. In this contribution, we analyze IP shocks generated by Corotating Interaction Region with the normal highly inclined from the solar wind velocity as well as IP shocks generated as a result of Coronal Mass Ejection with the normal nearly aligned with the solar wind velocity. These events were observed on both dawn and dusk magnetospheric flanks. For a comprehensive analysis, we use a large constellation of the spacecraft (SOHO, ACE, Wind, GEOTAIL, IMP 8, Cluster, Double Star, Themis) orbiting in the solar wind (and near the bow shock), in the magnetosheath, and in the magnetosphere at the magnetopause vicinity. We discuss the IP shock interaction with the bow shock and/or magnetopause, changes of its orientation and propagation speed on different spatial scales. In addition, we analyze the properties of a new discontinuity generated by the IP shock - bow shock interaction.

  1. Misconceptions Surrounding Climate Change: A Review of the Literature

    NASA Astrophysics Data System (ADS)

    Templeton, C. M.; McNeal, K. S.; Libarkin, J.

    2011-12-01

    communicate and share resources in a common community. Many organizations are addressing these critical needs and we will compile these efforts in our analysis as well.

  2. Impacts of emerging contaminants on surrounding aquatic environment from a youth festival.

    PubMed

    Jiang, Jheng-Jie; Lee, Chon-Lin; Fang, Meng-Der; Tu, Bo-Wen; Liang, Yu-Jen

    2015-01-20

    The youth festival as we refer to Spring Scream, a large-scale pop music festival, is notorious for the problems of drug abuse and addiction. The origin, temporal magnitudes, potential risks and mass inputs of emerging contaminants (ECs) were investigated. Thirty targeted ECs were analyzed by solid-phase extraction and liquid chromatography coupled to tandem mass spectrometry (SPE-LC-MS/MS). Sampling strategy was designed to characterize EC behavior in different stages (before and after the youth festival), based on multivariate data analysis to explore the contributions of contaminants from normal condition to the youth festival. Wastewater influents and effluents were collected during the youth festival (approximately 600 000 pop music fans and youth participated). Surrounding river waters are also sampled to illustrate the touristic impacts during peak season and off-season. Seasonal variations were observed, with the highest concentrations in April (Spring Scream) and the lowest in October (off-season). Acetaminophen, diclofenac, codeine, ampicillin, tetracycline, erythromycin-H2O, and gemfibrozil have significant pollution risk quotients (RQs > 1), indicating ecotoxicological concerns. Principal component analysis (PCA) and weekly patterns provide a perspective in assessing the touristic impacts and address the dramatic changes in visitor population and drug consumption. The highest mass loads discharged into the aquatic ecosystem corresponded to illicit drugs/controlled substances such as ketamine and MDMA, indicating the high consumption of ecstasy during Spring Scream. PMID:25495157

  3. Computations of the fluid annulus surrounding a pump shaft in synchronous vibration. Final report. [PWR; BWR

    SciTech Connect

    Cohen, L.M.; Gross, M.B.; Yeung, W.

    1983-07-01

    The purpose of this study is to analyze the fluid forces that arise from the fluid annulus surrounding a pump shaft in synchronous vibration. The computational method for determining the fluid forces is based on the two-dimensional, incompressible implicit version of the STEALTH 2D code. Using this computational tool, this study analyzes pump-shaft synchronous vibrations both in the low-Reynolds-number laminar-flow regime and the high-Reynolds-number turbulent-flow regime. Moreover, the study was able to investigate both infinitesimal (perturbation) shaft displacements as well as finite (substantial) shaft displacements. The new numerical results predict forces from the fluid annulus which are substantially greater than the forces computed by extrapolating a perturbation analysis to finite displacements. The new forces are substantially greater because the two-dimensional calculations are much stiffer than the perturbation analysis, which neglects the radial-velocity component of the flow. The numerical results for the fluid forces are summarized by simple analytic formulas.

  4. Electromembrane surrounded solid phase microextraction using electrochemically synthesized nanostructured polypyrrole fiber.

    PubMed

    Mohammadkhani, Elham; Yamini, Yadollah; Rezazadeh, Maryam; Seidi, Shahram

    2016-04-22

    Electromembrane surrounded solid phase microextraction using conductive polymers as the sorbent is carried out for the first time for extraction of two antidepressants including amitriptyline (AMI) and doxepin (DOX), as model analytes. The polypyrrole coating was prepared and utilized as both cathode and SPME sorbent. Different variables such as the conditions for preparation of polypyrrole fiber, pH of the donor and the acceptor phases, applied voltage, and extraction time were optimized. Under the optimized conditions, figures of merit of the proposed method were investigated in human whole blood and urine samples. Intra- and inter-assay precisions ranged between 3.1-7.5% and 7.6-12.3%, respectively were obtained in different extraction media. Detection limits of 0.15 and 0.05 for AMI and 0.3 and 0.1ngmL(-1) for DOX were achieved in the urine and blood samples, respectively. Linearity of the method was studied up to 50.0ngmL(-1) for both analytes and coefficients of determination better than 0.9966 were achieved. Regardless of the high sample cleanup, which makes the proposed method suitable for analysis of drugs from complicated matrices, clean chromatograms were obtained. Finally, the proposed method was applied for analysis of AMI and DOX in different real samples and reasonable data were obtained. PMID:27033980

  5. An aerial radiological survey of the Portsmouth Gaseous Diffusion Plant and surrounding area, Portsmouth, Ohio

    SciTech Connect

    Not Available

    1992-09-01

    An aerial radiological survey was conducted from July 11--20, 1990, over an 83-square-kilometer (32-square-mile) area surrounding the Portsmouth Gaseous Diffusion Plant located near Portsmouth, Ohio. The survey was conducted at a nominal altitude of 91 meters (300 feet) with line spacings of 122 meters (400 feet). A contour map of the terrestrial gamma exposure rate extrapolated to 1 meter above ground level (AGL) was prepared and overlaid on an aerial photograph and a set of United States Geological Survey (USGS) topographic maps of the area. The terrestrial exposure rates varied from about 7 to 14 microroentgens per hour ([mu]R/h) at 1 meter above the ground. Analysis of the data for man-made sources and for the uranium decay product, protactinium-234m ([sup 234m]Pa), showed five sites within the boundaries of the Portsmouth Gaseous Diffusion Plant with elevated readings. Spectra obtained in the vicinity of the buildings at the Portsmouth Gaseous Diffusion Plant showed the presence of [sup 234m]Pa, a uranium-238 ([sup 238]U) decay product. In addition, spectral analysis of the data obtained over the processing plant facility showed gamma activity indicative of uranium-235 ([sup 234]U). No other man-made gamma ray emitting radioactive material was detected, either on or off the Portsmouth Gaseous Diffusion Plant property. Soil samples and pressurized ion chamber measurements were obtained at five different locations within the survey boundlaries to support the aerial data.

  6. AFAL: a web service for profiling amino acids surrounding ligands in proteins.

    PubMed

    Arenas-Salinas, Mauricio; Ortega-Salazar, Samuel; Gonzales-Nilo, Fernando; Pohl, Ehmke; Holmes, David S; Quatrini, Raquel

    2014-11-01

    With advancements in crystallographic technology and the increasing wealth of information populating structural databases, there is an increasing need for prediction tools based on spatial information that will support the characterization of proteins and protein-ligand interactions. Herein, a new web service is presented termed amino acid frequency around ligand (AFAL) for determining amino acids type and frequencies surrounding ligands within proteins deposited in the Protein Data Bank and for assessing the atoms and atom-ligand distances involved in each interaction (availability: http://structuralbio.utalca.cl/AFAL/index.html ). AFAL allows the user to define a wide variety of filtering criteria (protein family, source organism, resolution, sequence redundancy and distance) in order to uncover trends and evolutionary differences in amino acid preferences that define interactions with particular ligands. Results obtained from AFAL provide valuable statistical information about amino acids that may be responsible for establishing particular ligand-protein interactions. The analysis will enable investigators to compare ligand-binding sites of different proteins and to uncover general as well as specific interaction patterns from existing data. Such patterns can be used subsequently to predict ligand binding in proteins that currently have no structural information and to refine the interpretation of existing protein models. The application of AFAL is illustrated by the analysis of proteins interacting with adenosine-5'-triphosphate. PMID:25085083

  7. Ultrastructural characterization of soft tissues surrounding implanted hip prosthesis by complementary PIXE and TEM methods

    NASA Astrophysics Data System (ADS)

    Jallot, E.; Benhayoune, H.; Kilian, L.; Balossier, G.; Bonhomme, P.; Oudadesse, H.; Irigaray, J. L.

    We study soft tissues surrounding hip prostheses from three different patients. We evaluate the elemental composition of different fragments. The tissues are examined by means of two complementary methods in such analysis: Particle Induced X-ray Emission (PIXE) and Scanning Transmission Electron Microscopy (STEM) coupled with X-ray microanalysis (Energy Dispersive X-ray, EDX). These methods allow to determine locally at `macro' and `micro' level the chemistry of soft tissues. The findings confirmed the presence of metal in soft tissue near the three different hips. The tissues' composition undergoes important modifications with a systematic elevation of trace metal in patients with failed implants. We observe a corrosion which causes the continual release of particles into the tissues. Corrosion alters the shape size and chemical composition of wear particles embedded in soft tissue around the failed hip. EDX analysis showed that the wear particles contained varying quantities of titanium and aluminium. This phenomenon may be related with the variation of time of contact with soft tissues for each particle and Ti solubility.

  8. Detection of recent regional sea surface temperature warming in the Caribbean and surrounding region

    NASA Astrophysics Data System (ADS)

    Glenn, Equisha; Comarazamy, Daniel; González, Jorge E.; Smith, Thomas

    2015-08-01

    We show a sea surface temperature (SST) warming trend for the Caribbean and surrounding region over 1982-2012. Using an optimum interpolated SST product, a 30 year climatological analysis was generated to observe annual, monthly, and seasonal trends. Results show that SSTs are increasing annually for the region. For the two Caribbean rainy seasons, the Early Rainfall Season (ERS) and the Late Rainfall Season (LRS), estimated trends at 0.0161°C yr-1 and 0.0209°C yr-1 were observed, with high statistical significance. Subregional analysis revealed that warming is greatest in the Gulf of Mexico and north of South America during the ERS and LRS. Additionally, LRS averages for 1998-2012 reflect an increase in magnitude and intensity of the Atlantic Warm Pool (AWP) since the 1983-1997 period reflected in the AWP Area Index. Extreme increases/decreases in the time series show potential correlation with El Niño and the Southern Oscillation.

  9. The Space of an Object: Object Attention Alters the Spatial Gradient in the Surround

    ERIC Educational Resources Information Center

    Kravitz, Dwight Jacob; Behrmann, Marlene

    2008-01-01

    Although object-based attention enhances perceptual processing of information appearing within the boundaries of a selected object, little is known about the consequences for information in the object's surround. The authors show that distance from an attended object's center of mass determines reaction time (RT) to targets in the surround. Of 2…

  10. Measurement of the radiation field surrounding the Collider Detector at Fermilab

    SciTech Connect

    K. Kordas et al.

    2004-01-28

    We present here the first direct and detailed measurements of the spatial distribution of the ionizing radiation surrounding a hadron collider experiment. Using data from two different exposures we measure the effect of additional shielding on the radiation field around the Collider Detector at Fermilab (CDF). Employing a simple model we parameterize the ionizing radiation field surrounding the detector.

  11. Multiple components of surround modulation in primary visual cortex: multiple neural circuits with multiple functions?

    PubMed

    Nurminen, Lauri; Angelucci, Alessandra

    2014-11-01

    The responses of neurons in primary visual cortex (V1) to stimulation of their receptive field (RF) are modulated by stimuli in the RF surround. This modulation is suppressive when the stimuli in the RF and surround are of similar orientation, but less suppressive or facilitatory when they are cross-oriented. Similarly, in human vision surround stimuli selectively suppress the perceived contrast of a central stimulus. Although the properties of surround modulation have been thoroughly characterized in many species, cortical areas and sensory modalities, its role in perception remains unknown. Here we argue that surround modulation in V1 consists of multiple components having different spatio-temporal and tuning properties, generated by different neural circuits and serving different visual functions. One component arises from LGN afferents, is fast, untuned for orientation, and spatially restricted to the surround region nearest to the RF (the near-surround); its function is to normalize V1 cell responses to local contrast. Intra-V1 horizontal connections contribute a slower, narrowly orientation-tuned component to near-surround modulation, whose function is to increase the coding efficiency of natural images in manner that leads to the extraction of object boundaries. The third component is generated by topdown feedback connections to V1, is fast, broadly orientation-tuned, and extends into the far-surround; its function is to enhance the salience of behaviorally relevant visual features. Far- and near-surround modulation, thus, act as parallel mechanisms: the former quickly detects and guides saccades/attention to salient visual scene locations, the latter segments object boundaries in the scene. PMID:25204770

  12. Long-range recruitment of Martinotti cells causes surround suppression and promotes saliency in an attractor network model

    PubMed Central

    Krishnamurthy, Pradeep; Silberberg, Gilad; Lansner, Anders

    2015-01-01

    Although the importance of long-range connections for cortical information processing has been acknowledged for a long time, most studies focused on the long-range interactions between excitatory cortical neurons. Inhibitory interneurons play an important role in cortical computation and have thus far been studied mainly with respect to their local synaptic interactions within the cortical microcircuitry. A recent study showed that long-range excitatory connections onto Martinotti cells (MC) mediate surround suppression. Here we have extended our previously reported attractor network of pyramidal cells (PC) and MC by introducing long-range connections targeting MC. We have demonstrated how the network with Martinotti cell-mediated long-range inhibition gives rise to surround suppression and also promotes saliency of locations at which simple non-uniformities in the stimulus field are introduced. Furthermore, our analysis suggests that the presynaptic dynamics of MC is only ancillary to its orientation tuning property in enabling the network with saliency detection. Lastly, we have also implemented a disinhibitory pathway mediated by another interneuron type (VIP interneurons), which inhibits MC and abolishes surround suppression. PMID:26528143

  13. Information support of territorial wildlife management of Lake Baikal and the surrounding areas (Russia)

    NASA Astrophysics Data System (ADS)

    Lesnykh, Svetlana

    2013-04-01

    The UNESCO World Heritage Committee inscribed Lake Baikal in the World Heritage List under all four natural criteria as the most outstanding example of a freshwater ecosystem. It is the oldest and deepest lake in the world, which is the main freshwater reserve surrounded by a system of protected areas that have high scientific and natural values. However, there is a conflict between three main interests within the territory: the preservation of the unique ecosystem of the lake and its surrounding areas, the need for regional economic development, and protection of interests of the population, living on the shores of Lake Baikal. Solutions to the current challenges are seen in the development of control mechanisms for the wildlife management to ensure sustainable development and conservation of lake and the surrounding regions. For development mechanisms of territorial management of the complex and valuable area it is necessary to analyze features of its functioning and self-control (adaptable possibilities), allowing ecosystems to maintain their unique properties under influence of various external factors: anthropogenic (emissions, waste water, streams of tourists) and natural (climate change) load. While determining the direction and usage intensity of the territory these possibilities and their limits should be considered. Also for development of management strategy it is necessary to consider the relation of people to land and water, types of wildlife management, ownership, rent, protection from the negative effects, and etc. The relation of people to the natural area gives a chance to prioritize the direction in the resource use and their protection. Results of the scientific researches (reaction of an ecosystem on influence of various factors and system of relations to wildlife management objects) are the basis for the nature protection laws in the field of wildlife management and environmental protection. The methodology of legal zoning of the territory was

  14. Stress distributions in maxillary bone surrounding overdenture implants with different overdenture attachments.

    PubMed

    Chun, H-J; Park, D-N; Han, C-H; Heo, S-J; Heo, M-S; Koak, J-Y

    2005-03-01

    In this study, effects of different overdenture attachments on the stress distributions in the maxillary bone surrounding the overdenture implants are studied. Four different types of attachment are considered. They are rigid Dalbo Stud, movable Dalbo Stress Broken, movable Dalro, and movable O-ring attachments. Three-dimensional finite element analysis was conducted with commercial package to obtain the stress distributions in the maxillary bone. Varying the attachment types and angle of inclination of load, the stress distributions in the portions of compact bone and trabecular bone were monitored separately. The analysis was conducted by assuming two different boundary conditions at the interface between cap and overdenture abutment in order to evaluate influence of interface boundary condition on stress distribution in the maxillary bone. They were perfect bonding condition and contact with friction at the interfaces. However, it is preferable to assume perfect bond condition at the interface for rigid type attachment systems and contact with friction at the interface for movable type attachment systems. From the numerical results, it was found that the load transfer mechanism of the implant system is altered significantly by the types of the overdenture attachment and also special care must be taken to assign proper boundary conditions at the interface for the analysis. The movable type Dalro attachment generated the highest maximum effective stress in the maxillary bone among the models under the same inclined loading condition for contact with friction. The rigid type Dalbo Stud attachment generated the smallest maximum effective stress in the maxillary bone among the models under the same inclined loading condition for perfect bonding condition. PMID:15707430

  15. Measurement of the optimum surround ratio inducing the highest perceived image contrast

    NASA Astrophysics Data System (ADS)

    Baek, Ye Seul; Kim, Youn Jin; Kim, Hong-Suk; Park, Seung-Ok

    2010-10-01

    Much research has shown that perceived image contrast increases as the surround luminance increases, but a number of recent studies reported opposite trends under higher surround luminance levels. We measured the change in perceived image contrast under a wide range of surround luminance levels covering from dark up to 2087 cd/m2. A large-area illuminator was used to illuminate the surround. It consists of 23 dimmable fluorescent lamps and a diffuser. Its maximum luminance is 2087 cd/m2 and could be adjusted to six lower levels. A set of paired comparison experiments was conducted to compare the perception of image contrast under seven different surround luminance levels. The results showed that the perceived image contrast varies with surround luminance and the maximum perceived image contrast is found near a surround ratio (SR) of 1. As SR increases from 0 to 1, the z score is increased, which can be fully expected by the Bartleson and Breneman effect. However, it is drastically decreased in the region of SR > 1; thus, the perceived image contrast is eventually decreased.

  16. Stimulus-dependency and mechanisms of surround modulation in cortical area MT

    PubMed Central

    Huang, Xin; Albright, Thomas D.; Stoner, Gene R.

    2009-01-01

    The perceptual interpretation of a given visual feature depends on the surrounding context. To explore the neural mechanisms underlying such contextual interactions in the motion domain, we studied responses of neurons in cortical area MT of macaque monkeys while presenting a variety of center-surround stimuli that stimulated both the classical receptive visual field (CRF) and the receptive field surround. In human psychophysical experiments, the perceptual impact of the surround stimulus on the center stimulus varied from motion capture (“integration”) to motion contrast (“segmentation”). In our neurophysiological experiments, the directional tuning of surround modulation with these stimuli ranged from antagonistic (consistent with motion contrast) to integrative (consistent with motion capture) and agreed qualitatively with perception under some but not all conditions. Most strikingly, for a stimulus that elicited perceptual motion contrast, surround modulation was integrative if the CRF stimulus was ambiguous due to the aperture problem. In addition, we found that surround modulation was linked to response magnitude: stimuli eliciting the largest responses yielded the strongest antagonism and those eliciting the smallest responses yielded the strongest integration. We developed a neural network model that accounts for this finding as well as a previous finding that surround suppression in area MT is contrast-dependent. Our findings suggest that changes in MT surround modulation result from shifts in the balance between directionally-tuned excitation and inhibition mediated by changes in input strength. We speculate that input strength is, in turn, linked with the ambiguity of the motion present within the CRF. PMID:19091978

  17. Geochemistry and environmental threats of soils surrounding an abandoned mercury mine.

    PubMed

    Bori, Jaume; Vallès, Bettina; Navarro, Andrés; Riva, Maria Carme

    2016-07-01

    The closure of mercury mining areas is generally associated with a release of Hg and other metals into the environment due to the abandonment of mining wastes. Because of their potential toxic properties, the mobilization of particulate and soluble metal species is of major concern. In the present study, the environmental risks posed by soils surrounding an abandoned mercury mining area in Valle del Azogue (Almeria, Spain) are assessed through the determination of physical-chemical parameters, the quantification of metal concentrations, and the application of aquatic and terrestrial ecotoxicity bioassays. Chemical analysis of soil samples revealed concentrations of Hg, As, Ba, Pb, Sb, and Zn above international intervention values. Results from terrestrial tests showed detrimental effects in all studied organisms (Eisenia foetida, Folsomia candida, and different plant species) and revealed the avoidance response of earthworms as the most sensitive endpoint. Surprisingly, the most toxic samples were not the ones with higher metal contents but the ones presenting higher electrical conductivity. Aquatic ecotoxicity tests with Vibrio fischeri, Raphidocelis subcapitata, Daphnia magna, and Danio rerio were in accordance with terrestrial tests, confirming the need to couple environmental chemistry with ecotoxicological tools for the proper assessment of metal-contaminated sites. In view of the results, a remediative intervention of the studied area is recommended. PMID:26996905

  18. Sand fly fauna (Diptera: Psychodidae) from the Goytacazes National Forest and surrounding areas of southeastern Brazil.

    PubMed

    das Virgens, Thieres Marassati; Rezende, Helder Ricas; de Souza Pinto, Israel; Falqueto, Aloísio

    2015-06-01

    Most studies of the sand fly fauna in southeastern Brazil are conducted in the peridomiciliary environment of leishmaniasis endemic regions. Therefore, to increase the knowledge about diversity and richness of sand fly conservation areas, we describe here the sand fly fauna from the National Forest of Goytacazes (NFG), state of Espírito Santo, Brazil, and its surroundings areas. We also used sand fly fauna records from eight conservations units within the state of Espírito Santo to understand the similarity and relationships among them. The sand flies were simultaneously collected from June, 2008 to May, 2009 in two different environments: a preserved environment represented by the NFG and a modified environment represented by a peridomicile. To establish the similarity among the conservation units, we used a method very similar to parsimony analysis of endemism. We collected 2,466 sand fly specimens belonging to 13 species. Pressatia choti and Nyssomyia intermedia were the most abundant sand fly species. Ny. intermedia is a known vector of Leishmania braziliensis and epidemiological surveillance must be conducted in the area. We discuss aspects regarding the diversity of sand flies as well as the risk of transmission of Leishmania parasites in the area. We also provide for the first time a hypothesis of similarity relationships among conservation units within the state of Espírito Santo. PMID:26047181

  19. μ-PIV measurements of the ensemble flow fields surrounding a migrating semi-infinite bubble

    PubMed Central

    Yamaguchi, Eiichiro; Smith, Bradford J.; Gaver, Donald P.

    2012-01-01

    Microscale particle image velocimetry (μ-PIV) measurements of ensemble flow fields surrounding a steadily-migrating semi-infinite bubble through the novel adaptation of a computer controlled linear motor flow control system. The system was programmed to generate a square wave velocity input in order to produce accurate constant bubble propagation repeatedly and effectively through a fused glass capillary tube. We present a novel technique for re-positioning of the coordinate axis to the bubble tip frame of reference in each instantaneous field through the analysis of the sudden change of standard deviation of centerline velocity profiles across the bubble interface. Ensemble averages were then computed in this bubble tip frame of reference. Combined fluid systems of water/air, glycerol/air, and glycerol/Si-oil were used to investigate flows comparable to computational simulations described in Smith and Gaver (2008) and to past experimental observations of interfacial shape. Fluorescent particle images were also analyzed to measure the residual film thickness trailing behind the bubble. The flow fields and film thickness agree very well with the computational simulations as well as existing experimental and analytical results. Particle accumulation and migration associated with the flow patterns near the bubble tip after long experimental durations are discussed as potential sources of error in the experimental method. PMID:23049158

  20. Design and fabrication considerations for stainless steel liquid helium jackets surrounding SCRF cavities

    NASA Astrophysics Data System (ADS)

    Bonnema, E. C.; Cunningham, E. K.; Rumel, J. D.

    2014-01-01

    The Department of Energy requires its subcontractors to meet 10 CFR 851 Appendix A Part 4 for all new pressure vessels and pressure piping. The stainless steel pressure vessel boundaries surrounding SCRF cavities fall under this requirement. Methods for meeting this requirement include design and fabrication of the pressure vessels to meet the requirements of the ASME Boiler & Pressure Vessel Code Section VIII Division 1 or Division 2. Design considerations include determining whether the configuration of the SCRF cavity can be accommodated under the rules of Division 1 or must be analyzed under Division 2 Part 4 Design by Rule Requirements or Part 5 Design by Analysis Requirements. Regardless of the Division or Part choice, designers will find the rules of the ASME Code require thicker pressure boundary members, larger welds, and additional non-destructive testing and quality assurance requirements. These challenges must be met and overcome by the fabricator through the development of robust, detailed, and repeatable manufacturing processes. In this paper we discuss the considerations for stainless steel pressure vessels that must meet the ASME Code and illustrate the discussion with examples from direct experience fabricating such vessels.

  1. A crustal seismic velocity model for the UK, Ireland and surrounding seas

    USGS Publications Warehouse

    Kelly, A.; England, R.W.; Maguire, Peter K.H.

    2007-01-01

    A regional model of the 3-D variation in seismic P-wave velocity structure in the crust of NW Europe has been compiled from wide-angle reflection/refraction profiles. Along each 2-D profile a velocity-depth function has been digitised at 5 km intervals. These 1-D velocity functions were mapped into three dimensions using ordinary kriging with weights determined to minimise the difference between digitised and interpolated values. An analysis of variograms of the digitised data suggested a radial isotropic weighting scheme was most appropriate. Horizontal dimensions of the model cells are optimised at 40 ?? 40 km and the vertical dimension at 1 km. The resulting model provides a higher resolution image of the 3-D variation in seismic velocity structure of the UK, Ireland and surrounding areas than existing models. The construction of the model through kriging allows the uncertainty in the velocity structure to be assessed. This uncertainty indicates the high density of data required to confidently interpolate the crustal velocity structure, and shows that for this region the velocity is poorly constrained for large areas away from the input data. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

  2. A deformation mechanism of hard metal surrounded by soft metal during roll forming

    PubMed Central

    YU, Hailiang; TIEU, A. Kiet; LU, Cheng; LIU, Xiong; GODBOLE, Ajit; LI, Huijun; KONG, Charlie; QIN, Qinghua

    2014-01-01

    It is interesting to imagine what would happen when a mixture of soft-boiled eggs and stones is deformed together. A foil made of pure Ti is stronger than that made of Cu. When a composite Cu/Ti foil deforms, the harder Ti will penetrate into the softer Cu in the convex shapes according to previously reported results. In this paper, we describe the fabrication of multilayer Cu/Ti foils by the roll bonding technique and report our observations. The experimental results lead us to propose a new deformation mechanism for a hard metal surrounded by a soft metal during rolling of a laminated foil, particularly when the thickness of hard metal foil (Ti, 25 μm) is much less than that of the soft metal foil (Cu, 300 μm). Transmission Electron Microscope (TEM) imaging results show that the hard metal penetrates into the soft metal in the form of concave protrusions. Finite element simulations of the rolling process of a Cu/Ti/Cu composite foil are described. Finally, we focus on an analysis of the deformation mechanism of Ti foils and its effects on grain refinement, and propose a grain refinement mechanism from the inside to the outside of the laminates during rolling. PMID:24853192

  3. A distributed code for color in natural scenes derived from center-surround filtered cone signals

    PubMed Central

    Kellner, Christian J.; Wachtler, Thomas

    2013-01-01

    In the retina of trichromatic primates, chromatic information is encoded in an opponent fashion and transmitted to the lateral geniculate nucleus (LGN) and visual cortex via parallel pathways. Chromatic selectivities of neurons in the LGN form two separate clusters, corresponding to two classes of cone opponency. In the visual cortex, however, the chromatic selectivities are more distributed, which is in accordance with a population code for color. Previous studies of cone signals in natural scenes typically found opponent codes with chromatic selectivities corresponding to two directions in color space. Here we investigated how the non-linear spatio-chromatic filtering in the retina influences the encoding of color signals. Cone signals were derived from hyper-spectral images of natural scenes and preprocessed by center-surround filtering and rectification, resulting in parallel ON and OFF channels. Independent Component Analysis (ICA) on these signals yielded a highly sparse code with basis functions that showed spatio-chromatic selectivities. In contrast to previous analyses of linear transformations of cone signals, chromatic selectivities were not restricted to two main chromatic axes, but were more continuously distributed in color space, similar to the population code of color in the early visual cortex. Our results indicate that spatio-chromatic processing in the retina leads to a more distributed and more efficient code for natural scenes. PMID:24098289

  4. The Impact of Green Stormwater Infrastructure Installation on Surrounding Health and Safety

    PubMed Central

    Low, Sarah C.; Henning, Jason; Branas, Charles C.

    2015-01-01

    Objectives. We investigated the health and safety effects of urban green stormwater infrastructure (GSI) installments. Methods. We conducted a difference-in-differences analysis of the effects of GSI installments on health (e.g., blood pressure, cholesterol and stress levels) and safety (e.g., felonies, nuisance and property crimes, narcotics crimes) outcomes from 2000 to 2012 in Philadelphia, Pennsylvania. We used mixed-effects regression models to compare differences in pre- and posttreatment measures of outcomes for treatment sites (n = 52) and randomly chosen, matched control sites (n = 186) within multiple geographic extents surrounding GSI sites. Results. Regression-adjusted models showed consistent and statistically significant reductions in narcotics possession (18%–27% less) within 16th-mile, quarter-mile, half-mile (P < .001), and eighth-mile (P < .01) distances from treatment sites and at the census tract level (P < .01). Narcotics manufacture and burglaries were also significantly reduced at multiple scales. Nonsignificant reductions in homicides, assaults, thefts, public drunkenness, and narcotics sales were associated with GSI installation in at least 1 geographic extent. Conclusions. Health and safety considerations should be included in future assessments of GSI programs. Subsequent studies should assess mechanisms of this association. PMID:25602887

  5. Detection and Location of Icy Particles Surrounding 103P/Hartley 2

    NASA Astrophysics Data System (ADS)

    Hermalyn, B.; Farnham, T. L.; Schultz, P. H.; Kelley, M. S.; Lindler, D.; Thomas, P. C.; A'Hearn, M. F.

    2011-10-01

    The Deep Impact Flyby Spacecraft encountered comet 103P/Hartley 2 on November 4th, 2010 at a minimum distance of 694 km [1]. Both the High Resolution (HRI) and Medium Resolution Instruments (MRI) captured images of a field of debris enveloping the comet. Fine grain dust and ice (primarily detected in the HRI) and hundreds of discrete larger particles are apparent during encounter. The larger golf ball to basketball-sized particles are detected primarily near the nucleus (Fig. 1). This swarming of individual grains in the near-nucleus environment of Hartley 2 has not been observed in any other comet to date. The motion of the spacecraft instruments relative to the comet nucleus (including not only spacecraft velocity but pointing adjustments) provides sufficient parallax between successive images around closest approach to stereoscopically reconstruct the distance and displacement of these particles. In this study, we present an analysis of the identification, position, and motion of discrete ejected particles surrounding the comet.

  6. Ecological risk assessment of heavy metals in soils surrounding oil waste disposal areas.

    PubMed

    Xu, Jianling; Wang, Hanxi; Liu, Yuanyuan; Ma, Mengchao; Zhang, Tian; Zheng, Xiaoxue; Zong, Meihan

    2016-02-01

    More attention is being devoted to heavy metal pollution because heavy metals can concentrate in higher animals through the food chain, harm human health and threaten the stability of the ecological environment. In this study, the effects of heavy metals (Cu, Cr, Zn, Pb, Cd, Ni and Hg) emanating from oil waste disposal on surrounding soil in Jilin Province, China, were investigated. A potential ecological risk index was used to evaluate the damage of heavy metals and concluded that the degree of potential ecological damage of heavy metals can be ranked as follows: Hg > Cd > Pb > Cu > Ni > Cr > Zn. The average value of the potential ecological harm index (Ri) is 71.93, thereby indicating light pollution. In addition, this study researched the spatial distribution of soil heavy metals by means of ArcGIS (geographic information system) spatial analysis software. The results showed that the potential ecological risk index (R) of the large value was close to the distance from the oil waste disposal area; it is relatively between the degree of heavy metals in soil and the distance from the waste disposal area. PMID:26832722

  7. Deep crustal structure of the Cascade Range and surrounding regions from seismic refraction and magnetotelluric data

    USGS Publications Warehouse

    Stanley, W.D.; Mooney, W.D.; Fuis, G.S.

    1990-01-01

    Several regional seismic refraction and magnetotelluric (MT) profiles have been completed across the Cascade Range and surrounding geologic provinces in California, Oregon, and Washington. Analysis of three MT and two seismic refraction profiles in Oregon and a coincident MT and refraction profile in northern California show a high degree of correlation between resistivity and velocity models. The main feature that is evident in both data sets is a highly conductive (2-20 ohm m) zone that occurs at depths of 6-20 km and largely within a midcrustal velocity layer of 6.4-6.6 km/s, overlying a lower crust with velocities of 7.0-7.4 km/s. Accretionary structures in the southern Washington Cascades have been shown to be related to stress release in the area of Mount St. Helens. In order to explain the similar structures in the MT and refraction models for Oregon and California, a model is proposed involving the effects of metamorphic zonation to produce the velocity structure, combined with metamorphically produced fluids and partial melt to produce the deep conductor. -from Authors

  8. Comparison of soil and forest floor properties of floodplain and surrounding forests in Igneada, Turkey.

    PubMed

    Tecimen, Huseyin Baris; Kavgaci, Ali

    2010-01-01

    In this study some soil and forest floor characteristics of floodplain forest, thermophile forest and sand dune were investigated at Igneada, Turkey. In this context, surface soil samples were analyzed and compared to each other in the extension of soil physical, chemical properties and as plant nutrition environment. To investigate the soil characteristics soil samples were collected from 48 sampling point. The distribution of the soils revealed that remarkably physical soil properties figure the ordination of soils in principal component analysis (PCA). We concluded that floodplain forests have quite different soil properties from the thermophile forest and sand dunes under the continuous effect of surrounding thermophile forest land with less sandy proportion to soil texture 52.4 at floodplain forest, 64.0% at thermophile forest and 91.0% at sand dunes and highly organic carbon 5.619, 4.191 and 0.478% respectively at 0-5 cm depth and total nitrogen content 0.213, 0.078 and 0.056% for floodplain forest > thermophile forest > sand dune soils, respectively. Weight and organic matter contents of forest floor were significantly higher in the thermophile forests. PMID:20648824

  9. YouTube: a gauge of public perception and awareness surrounding epilepsy.

    PubMed

    Lo, Alto S; Esser, Michael J; Gordon, Kevin E

    2010-04-01

    Epilepsy is a common neurological disorder. Despite advances in research and epilepsy education campaigns, there remains significant misinformation and persistent stigma. The Internet is a widely used source for information and communication. Therefore, we sampled the video-sharing website YouTube (www.youtube.com) to see how epilepsy is being perceived. The top 10 videos are being viewed 3200 times daily. All videos showed statistically significant differences for within-variable analysis in at least one variable: empathy or knowledge (P<0.001). Further assessment revealed that "real-life" epilepsy videos generated the most hits and comments, had the most favorable empathetic scoring, but provided little to no information to viewers. Conversely, videos providing information had largely neutral or negative empathy scores. Video-sharing websites, like YouTube, have the potential to remediate the significant misinformation and persistent stigma surrounding epilepsy. This study underscores the importance of recognizing the significant attributes of videos that engage the viewers. PMID:20236867

  10. High diversity of microplankton surrounds deep-water coral reef in the Norwegian Sea.

    PubMed

    Jensen, Sigmund; Bourne, David G; Hovland, Martin; Murrell, J Colin

    2012-10-01

    Coral reefs that exist in the depths of the oceans are surrounded by Eukarya, Archaea and bacterial communities that may play an important role in the nutrition and health of the reef. The first interdomain community structure of planktonic organisms in seawater from a deep-water coral reef is described. Community profiling and analysis of ribosomal RNA gene sequences from a coral reef system at 350 m depth in the Norwegian Sea revealed a rich diversity of Eukarya and Bacteria and a moderate diversity of Archaea. Most sequences affiliated with marine microplankton from deep-sea to cold-surface regions, with many sequences being similar to those described in studies of mesopelagic and oxygen minimum zones. Dominant phylotypes belonged to the Alveolata (group I, II, dinoflagellates), Stramenopiles (silicoflagellates), Alphaproteobacteria (Pelagibacter ubique), Gammaproteobacteria (ARCTIC96BD-19), Bacteroidetes (Flavobacteria) and mesophilic Crenarchaeota (Nitrosopumilus maritimus). Several rare and novel members of the community fell into distinct phylogenetic groups. The inferred function of dominant community members suggested autotrophs that utilise light, ammonium or sulphide, and lifestyles based on host associations. The high diversity reflected a microplankton community structure, which is significantly different from that of microplankton collected at the same depth at a pelagic station away from reefs. PMID:22571287

  11. Is there an influence of the surrounding material on the response of the alanine dosimetry system?

    NASA Astrophysics Data System (ADS)

    Anton, Mathias; Kapsch, Ralf-Peter; Hackel, Thomas

    2009-04-01

    In a combined experimental and Monte Carlo study the possible influence of the surrounding material on the response of the alanine dosimetry system was investigated. The aim of this work was to estimate the uncertainties induced by the surroundings with respect to quality assurance measurements for radiotherapy, for example in humanoid phantoms. Six different materials were tested. The electron density range covered comprises the range present in human tissue. No significant influence of the surrounding material could be found for irradiations in the 60Co reference field of the Physikalisch-Technische Bundesanstalt (PTB).

  12. Inner cauchy horizon of axisymmetric and stationary black holes with surrounding matter in einstein-maxwell theory.

    PubMed

    Ansorg, Marcus; Hennig, Jörg

    2009-06-01

    We study the interior electrovacuum region of axisymmetric and stationary black holes with surrounding matter and find that there exists always a regular inner Cauchy horizon inside the black hole, provided the angular momentum J and charge Q of the black hole do not vanish simultaneously. In particular, we derive an explicit relation for the metric on the Cauchy horizon in terms of that on the event horizon. Moreover, our analysis reveals the remarkable universal relation (8piJ);{2}+(4piQ;{2});{2}=A;{+}A;{-}, where A+ and A- denote the areas of event and Cauchy horizon, respectively. PMID:19658851

  13. Variation of Fundamental Mode Surface Wave Group Velocity Dispersion in Iran and the Surrounding Region

    NASA Astrophysics Data System (ADS)

    Rham, D. J.; Preistley, K.; Tatar, M.; Paul, A.

    2006-12-01

    We present group velocity dispersion results from a study of regional fundamental mode Rayleigh and Love waves propagating across Iran and the surrounding region. Data for these measurements comes from field deployments within Iran by the University of Cambridge (GBR) and the Universite Joseph-Fourier (FRA) in conjunction with International Institute of Earthquake Engineering and Seismology (Iran), in addition to data from IRIS and Geofone. 1D path- averaged dispersion measurements have been made for ~5500 source-receiver paths using multiple filter analysis. We combine these observations in a tomographic inversion to produce group velocity images between 10 and 60 s period. Because of the dense path coverage, these images have substantially higher lateral resolution for this region than is currently available from global and regional group velocity studies. We observe variations in short-period wave group velocity which is consistent with the surface geology. Low group velocities (2.00-2.55 km/s) at short periods (10-20 s), for both Rayleigh and Love waves are observed beneath thick sedimentary deposits; The south Caspian Basin, Black Sea, the eastern Mediterranean, the Persian Gulf, the Makran, the southern Turan shield, and the Indus and Gangetic basins. Somewhat higher group velocity (2.80-3.15 km/s for Rayleigh, and 3.00-3.40 km/s for Love) at these periods occur in sediment poor regions, such as; the Turkish-Iranian plateau, the Arabian shield, and Kazakhstan. At intermediate periods (30-40 s) group velocities over most of the region are low (2.65-3.20 km/s for Rayleigh, and 2.80-3.45 km/s for love) compared to Arabia (3.40-3.70 km/s Rayleigh, 3.50-4.0 km/s Love). At longer periods (50-60 s) Love wave group velocities remain low (3.25-3.70 km/s) over most of Iran, but there are even lower velocities (2.80-3.00 km/s) still associated with the thick sediments of the south Caspian basin, the surrounding shield areas have much higher group velocities (3

  14. Analysing land cover and land use change in the Matobo National Park and surroundings in Zimbabwe

    NASA Astrophysics Data System (ADS)

    Scharsich, Valeska; Mtata, Kupakwashe; Hauhs, Michael; Lange, Holger; Bogner, Christina

    2016-04-01

    Natural forests are threatened worldwide, therefore their protection in National Parks is essential. Here, we investigate how this protection status affects the land cover. To answer this question, we analyse the surface reflectance of three Landsat images of Matobo National Park and surrounding in Zimbabwe from 1989, 1998 and 2014 to detect changes in land cover in this region. To account for the rolling countryside and the resulting prominent shadows, a topographical correction of the surface reflectance was required. To infer land cover changes it is not only necessary to have some ground data for the current satellite images but also for the old ones. In particular for the older images no recent field study could help to reconstruct these data reliably. In our study we follow the idea that land cover classes of pixels in current images can be transferred to the equivalent pixels of older ones if no changes occurred meanwhile. Therefore we combine unsupervised clustering with supervised classification as follows. At first, we produce a land cover map for 2014. Secondly, we cluster the images with clara, which is similar to k-means, but suitable for large data sets. Whereby the best number of classes were determined to be 4. Thirdly, we locate unchanged pixels with change vector analysis in the images of 1989 and 1998. For these pixels we transfer the corresponding cluster label from 2014 to 1989 and 1998. Subsequently, the classified pixels serve as training data for supervised classification with random forest, which is carried out for each image separately. Finally, we derive land cover classes from the Landsat image in 2014, photographs and Google Earth and transfer them to the other two images. The resulting classes are shrub land; forest/shallow waters; bare soils/fields with some trees/shrubs; and bare light soils/rocks, fields and settlements. Subsequently the three different classifications are compared and land changes are mapped. The main changes are

  15. A case study of urban student and teacher experiences surrounding an outdoor environmental science field trip

    NASA Astrophysics Data System (ADS)

    Preusch, Peggy L.

    2009-12-01

    Field trips provide opportunities for students to experience many different contexts beyond the classroom, and are a popular choice of K-12 teachers in the US. Recent interest in learning that occurs at informal science education centers such as museums, zoos and aquariums has stimulated studies of the relationship between learning in and outside of schools. Although many studies focus on the teachers, the contexts, and/or the students during the field trip, only a few look at the entire process of learning by including the classroom setting before and after the field trip. This study was designed to develop understandings of the student process of learning during and surrounding an environmental science field trip to an outdoor setting. John Dewey's extensive writings on the relationship between experience and learning informed the analysis, creating a focus on active and passive elements of the experience, continuity within and across contexts, the interactive nature of the experience and the importance of subject matter. An exploration of environmental education (EE), environmental science (ES), and nature study as content revealed the complexities of the subject matter of the field trip that make its presentation problematic. An urban school was chosen to contribute to the research literature about urban student learning in outdoor environments. During the field trip, the students' active engagement with each other and the environment supported meaningful remembrances of the field trip experiences during interviews after the field trip. The students accurately described plants and animals they had observed in different habitats during the field trip. They also made connections with their home life and prior experiences in the outdoors as they discussed the field trip and drew pictures that represented their experiences. One student integrated his outdoor experience with a language arts assignment as he reflected deeply on the field trip. One implication of this

  16. Determining relationships and mechanisms between tropospheric ozone column concentrations and tropical biomass burning in Thailand and its surrounding regions

    NASA Astrophysics Data System (ADS)

    Sonkaew, Thiranan; Macatangay, Ronald

    2015-06-01

    This study aims to determine the variability and trends of tropical biomass burning, tropospheric ozone levels from 2005-2012 in Thailand and the ozone transport from the surrounding regions. Intense biomass burning and tropospheric ozone in this area have a seasonal variability with the maximum generally occurring during the dry season. The northern part of Thailand was observed to have high tropospheric ozone during the dry peak season in April. Forward trajectory analysis determined that ozone sources due to biomass burning in the northern and western surrounding regions (Myanmar, Laos and India) enhance the tropospheric ozone column in northern Thailand. Seasonal variations were also seen for the middle and northeastern regions of Thailand. During August, most biomass burning occurs in Indonesia and Malaysia. However, forward trajectory analysis showed that the effect in the tropospheric ozone column level in the southern part of Thailand is minimal from these regions. Eight-year trends of tropospheric ozone column were also calculated for the different regions of Thailand. However, statistical analysis showed that these trends were not significant. The interannual variability of the tropospheric ozone column concentrations due to El Niño Southern Oscillation were also investigated. It was observed that the best correlation of the tropospheric ozone column with the Oceanic Niño Index (ONI) occured when ONI was advanced 3 months for the north, northeast and south regions of Thailand and 4 months for the middle region of Thailand.

  17. 77 FR 60741 - Convening of an Accountability Review Board To Examine the Circumstances Surrounding the Deaths...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-04

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Convening of an Accountability Review Board To Examine the Circumstances Surrounding the Deaths of Personnel... deaths of Ambassador J. Christopher Stevens, Information Management Officer Sean Smith, and...

  18. 36 CFR 293.12 - Access to surrounded State and private lands.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., DEPARTMENT OF AGRICULTURE WILDERNESS-PRIMITIVE AREAS § 293.12 Access to surrounded State and private lands... Forest Wilderness shall be given access as provided in subpart D of part 251 of this chapter....

  19. 36 CFR 293.12 - Access to surrounded State and private lands.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., DEPARTMENT OF AGRICULTURE WILDERNESS-PRIMITIVE AREAS § 293.12 Access to surrounded State and private lands... Forest Wilderness shall be given access as provided in subpart D of part 251 of this chapter....

  20. 36 CFR 293.12 - Access to surrounded State and private lands.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., DEPARTMENT OF AGRICULTURE WILDERNESS-PRIMITIVE AREAS § 293.12 Access to surrounded State and private lands... Forest Wilderness shall be given access as provided in subpart D of part 251 of this chapter....

  1. 36 CFR 293.12 - Access to surrounded State and private lands.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., DEPARTMENT OF AGRICULTURE WILDERNESS-PRIMITIVE AREAS § 293.12 Access to surrounded State and private lands... Forest Wilderness shall be given access as provided in subpart D of part 251 of this chapter....

  2. 36 CFR 293.12 - Access to surrounded State and private lands.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., DEPARTMENT OF AGRICULTURE WILDERNESS-PRIMITIVE AREAS § 293.12 Access to surrounded State and private lands... Forest Wilderness shall be given access as provided in subpart D of part 251 of this chapter....

  3. Niches of dominant fish in the waters surrounding the Taishan Islands, China

    NASA Astrophysics Data System (ADS)

    Yang, Lu; Chen, Jie; Yang, Shengyun; Zhong, Huiqi; Ju, Peilong; Yang, Shunliang; Sun, Qinqin; Chen, Mingru

    2016-07-01

    An index of relative importance (IRI) was employed to screen for dominant fish in the waters surrounding the Taishan Islands, China, using data from four seasonal trawl surveys undertaken between 2012 and 2013. Niche breadth and niche overlap were measured using the Feinsinger and Morisita-Horn indices, respectively, and the characteristics and seasonal variations in the niches of dominant fish were assessed via non-metric multidimensional scaling (NMDS) and cluster analysis. A total of 80 fish species, including 16 dominant species, were recorded. Only Amblychaeturichthys hexanema was dominant in all seasons. According to niche breadth values and NMDS, the 16 dominant species were grouped into the following three types: (1) wide niche breadth species, including Cynoglossus macrolepidotus, A. hexanema, and Trypauchen vagina, among others; (2) medium niche breadth species, including Setipinna taty and Johnius belangerii; and (3) narrow niche breadth species, including Atrobucca nibe and Coilia mystus. Most species with a wider niche breadth were demersal fish with a lower swimming capability and even distribution. The niche breadth of migrating fish was narrower than that of settled fish. At a given spatial scale, fish with stronger swimming capabilities had a narrower niche breadth. Niche overlap, which is associated with niche specialization, ranged from 0.000 to 0.886 and had an annual mean value of 0.314. In summer and autumn, niche overlap was relatively high within species of the Sciaenidae family and within species of the Gobiidae in autumn. Differences in thermophily, feeding habits, food organism abundance/distribution and predator-prey relationships affected the niche overlap of fish in this area. Cluster analysis revealed that species with the narrowest niche breadth and lowest niche overlap values usually displayed lower aggregation and greater distribution differences compared with other species.

  4. Niches of dominant fish in the waters surrounding the Taishan Islands, China

    NASA Astrophysics Data System (ADS)

    Yang, Lu; Chen, Jie; Yang, Shengyun; Zhong, Huiqi; Ju, Peilong; Yang, Shunliang; Sun, Qinqin; Chen, Mingru

    2015-11-01

    An index of relative importance (IRI) was employed to screen for dominant fish in the waters surrounding the Taishan Islands, China, using data from four seasonal trawl surveys undertaken between 2012 and 2013. Niche breadth and niche overlap were measured using the Feinsinger and Morisita-Horn indices, respectively, and the characteristics and seasonal variations in the niches of dominant fish were assessed via non-metric multidimensional scaling (NMDS) and cluster analysis. A total of 80 fish species, including 16 dominant species, were recorded. Only Amblychaeturichthys hexanema was dominant in all seasons. According to niche breadth values and NMDS, the 16 dominant species were grouped into the following three types: (1) wide niche breadth species, including Cynoglossus macrolepidotus, A. hexanema, and Trypauchen vagina, among others; (2) medium niche breadth species, including Setipinna taty and Johnius belangerii; and (3) narrow niche breadth species, including Atrobucca nibe and Coilia mystus. Most species with a wider niche breadth were demersal fish with a lower swimming capability and even distribution. The niche breadth of migrating fish was narrower than that of settled fish. At a given spatial scale, fish with stronger swimming capabilities had a narrower niche breadth. Niche overlap, which is associated with niche specialization, ranged from 0.000 to 0.886 and had an annual mean value of 0.314. In summer and autumn, niche overlap was relatively high within species of the Sciaenidae family and within species of the Gobiidae in autumn. Differences in thermophily, feeding habits, food organism abundance/distribution and predator-prey relationships affected the niche overlap of fish in this area. Cluster analysis revealed that species with the narrowest niche breadth and lowest niche overlap values usually displayed lower aggregation and greater distribution differences compared with other species.

  5. Emission of ESBL/AmpC-producing Escherichia coli from pig fattening farms to surrounding areas.

    PubMed

    von Salviati, Christina; Laube, Henriette; Guerra, Beatriz; Roesler, Uwe; Friese, Anika

    2015-01-30

    The presence of ESBL/AmpC-producing Escherichia coli in livestock such as pigs has been known for some time. However, to date there is little information about the transmission of these resistant bacteria between pig farms and their surroundings. Thus, the aim of this study was to explore this topic by investigating seven German pig fattening farms. Samples from outside (including ground surfaces, ambient air, slurry and digestate from biogas plants) and, in parallel, from inside the pig barns (including pig feces, dust, barn air, flies and mice feces) were examined for ESBL/AmpC-producing E. coli and selected isolates were compared by pulsed-field gel electrophoresis (PFGE) analysis. 14/17 (82.4%) slurry samples and three of four samples of digestate from biogas plants tested positive for ESBL/AmpC-producing E. coli. In the vicinity of the pig barns these resistant bacteria were detected in 14/87 (16.1%) boot swabs taken from various ground surfaces and in 2/36 (6%) ambient air samples. Inside the pig barns, 6/63 (9.5%) barn air samples and a small proportion of flies and mice feces samples were ESBL/AmpC-positive. PFGE analysis proved fecal emission as well as a possible spread via flies, as identical ESBL-E. coli isolates were detected in slurry and on fertilized fields, as well as in flies and pooled feces from inside the barn and slurry. Contaminated slurry presented the major emission source for ESBL/AmpC-producing E. coli in the pig fattening farms, but a spread via the airborne route or via different vectors also seems possible. PMID:25465658

  6. Potential roles of the interaction between model V1 neurons with orientation-selective and non-selective surround inhibition in contour detection.

    PubMed

    Yang, Kai-Fu; Li, Chao-Yi; Li, Yong-Jie

    2015-01-01

    Both the neurons with orientation-selective and with non-selective surround inhibition have been observed in the primary visual cortex (V1) of primates and cats. Though the inhibition coming from the surround region (named as non-classical receptive field, nCRF) has been considered playing critical role in visual perception, the specific role of orientation-selective and non-selective inhibition in the task of contour detection is less known. To clarify above question, we first carried out computational analysis of the contour detection performance of V1 neurons with different types of surround inhibition, on the basis of which we then proposed two integrated models to evaluate their role in this specific perceptual task by combining the two types of surround inhibition with two different ways. The two models were evaluated with synthetic images and a set of challenging natural images, and the results show that both of the integrated models outperform the typical models with orientation-selective or non-selective inhibition alone. The findings of this study suggest that V1 neurons with different types of center-surround interaction work in cooperative and adaptive ways at least when extracting organized structures from cluttered natural scenes. This work is expected to inspire efficient phenomenological models for engineering applications in field of computational machine-vision. PMID:26136664

  7. Potential roles of the interaction between model V1 neurons with orientation-selective and non-selective surround inhibition in contour detection

    PubMed Central

    Yang, Kai-Fu; Li, Chao-Yi; Li, Yong-Jie

    2015-01-01

    Both the neurons with orientation-selective and with non-selective surround inhibition have been observed in the primary visual cortex (V1) of primates and cats. Though the inhibition coming from the surround region (named as non-classical receptive field, nCRF) has been considered playing critical role in visual perception, the specific role of orientation-selective and non-selective inhibition in the task of contour detection is less known. To clarify above question, we first carried out computational analysis of the contour detection performance of V1 neurons with different types of surround inhibition, on the basis of which we then proposed two integrated models to evaluate their role in this specific perceptual task by combining the two types of surround inhibition with two different ways. The two models were evaluated with synthetic images and a set of challenging natural images, and the results show that both of the integrated models outperform the typical models with orientation-selective or non-selective inhibition alone. The findings of this study suggest that V1 neurons with different types of center–surround interaction work in cooperative and adaptive ways at least when extracting organized structures from cluttered natural scenes. This work is expected to inspire efficient phenomenological models for engineering applications in field of computational machine-vision. PMID:26136664

  8. Mobile Learning: An Analysis of Student Preferences and Perceptions Surrounding Podcasting

    ERIC Educational Resources Information Center

    McCombs, Shawn William

    2010-01-01

    Today's learner arrives on our campuses with certain expectations, among them are technology innovation and availability, and the use of modern and efficient technology solutions to communicate and coexist. Meanwhile, institutions of higher learning across the country struggle with increased operating costs, decreasing legislative funding, and…

  9. An Empirically Informed Analysis of the Ethical Issues Surrounding Split Liver Transplantation in the United Kingdom.

    PubMed

    Moorlock, Greg; Neuberger, James; Bramhall, Simon; Draper, Heather

    2016-07-01

    Surgical advances have allowed for the development of split liver transplantation, providing two recipients with the opportunity to potentially benefit from one donated liver by splitting the liver into two usable parts. Although current data suggest that the splitting of livers provides overall benefit to the liver-recipient population, relatively low numbers of livers are actually split in the United Kingdom. This article addresses the question of whether ethical concerns are posing an unnecessary barrier to further increasing the number of life-saving transplantations. Recognizing that an important aspect of exploring these concerns is gaining insight into how transplant staff and patients regard splitting livers, the article presents the findings of a qualitative study examining the views of senior transplant staff and liver transplant patients in the UK and uses these to inform a commentary on the ethical issues relating to split liver transplantation. PMID:27348828

  10. Economic and Time-Sensitive Issues Surrounding CCS: A Policy Analysis.

    PubMed

    Maddali, Vijay; Tularam, Gurudeo Anand; Glynn, Patrick

    2015-08-01

    Are the existing global policies on combating global warming via the carbon capture and storage (CCS) method significant enough to curtail the temperature rise on time? We argue that it is already too late to have any reliance on CCS. The current status of CCS is that it is plagued by technical uncertainties, infrastructure, financial, and regulatory issues. The technology is far from maturity and, hence, commercialization. Simulations conducted in this work suggest that the relevance of CCS is completely defied if the annual emission growth rate is in excess of 2% between the years of 2015 and 2040. At such a growth rate, the annual emissions reduction between 2040 and 2100 will need to be in the vicinity of 5.5% by the year 2100. Considering an average annual emissions growth rate of 2.5% over the past decade, it seems unlikely that the emissions could be contained to a 2% growth level. CCS in its current shape and form is at odds with the economics of its implementation and the time in hand with which to play a significant role in a carbon mitigation strategy. There is an urgent need to rethink policies and strategies to combat global warming to at least some degree. PMID:26114417

  11. Elemental analysis of soils and Salix polaris in the town of Pyramiden and its surroundings (Svalbard).

    PubMed

    Krajcarová, Lucie; Novotný, Karel; Chattová, Barbora; Elster, Josef

    2016-05-01

    The contents of elements in the top soil (upper 5 cm) and deeper soil (5 to 10 cm) layers and in Salix polaris (leaves and stem) from the former Soviet mining town of Pyramiden and its close vicinity on the Svalbard archipelago were determined. The analyses covered major and trace elements, including heavy metals, in order to describe anthropogenic impacts related to the management of the mining town. Soil samples and plant tissues were analysed from 13 localities across and close to town vicinity. The plant ground cover of all sampling points was determined, and plant tissues (leaves and stem) were collected. Higher contents of Cd (3-11 mg kg(-1)) and Mo (11-33 mg kg(-1)) were detected in the soils. With relation to the world average concentration of metals in soils, the geo-accumulation indexes (Igeo) and the level of pollution of the analysed soils were classified into seven pollution grades. The soils of the studied localities were usually unpolluted (grade 1) when analysed for metals, with the soil pollution grades 4-6 identified only for Cd and Mo (moderately to strongly polluted). In Salix polaris, excessive amounts of Fe (60-1520 mg kg(-1)), Zn (80-1050 mg kg(-1)), Cd (0.2-5.5 mg kg(-1)) and Cr (0-3.6 mg kg(-1)) were observed. The Igeo of these elements, compared with values considered sufficient for plants, showed pollution grades from 2 to 6. The pollution load index (PLI) ranged between 0.49 and 1.01. Only one locality could be considered polluted having a PLI higher than 1. Plant/soil transfer factors (TF) for trace metals decreased in the following order: Zn > Cu > Cd > Mn > Ni > As > Mo > Pb > Co > Al > Cr > Fe. The principal contribution of this study consists in the assessment of the contamination of soils and plants by toxic heavy metals in an otherwise pristine environment of the Svalbard archipelago related to urban/industrial activities. PMID:26867690

  12. Persistence of Subcultural Organizations: An Analysis Surrounding the Process of Subcultural Change.

    ERIC Educational Resources Information Center

    Lont, Cynthia M.

    1990-01-01

    Examines the terms used to describe the process of subcultural change (adaptation, appropriation, commodization, cooptation, and incorporation), demonstrating their limits. Introduces a more exact term, "persistence," and recommends its use and the elimination of other terms. Uses one subcultural organization, Redwood Records (a women's music…

  13. Speak, Review, Change, Repeat: An Analysis of Discourse Surrounding Dilemmas at Admission, Review and Dismissal Meetings

    ERIC Educational Resources Information Center

    Mathews-Perez, Amy Lynn

    2013-01-01

    The purpose of this study was to understand the ways in which three parents of students with disabilities and three public school campus administrators negotiated dilemmas through discourse during Admission, Review, and Dismissal (ARD) meetings in a South Texas public school district. The participants in this study included the stakeholders in ARD…

  14. BVRIJHK photometry and proper motion analysis of NGC 6253 and the surrounding field

    NASA Astrophysics Data System (ADS)

    Montalto, M.; Piotto, G.; Desidera, S.; Platais, I.; Carraro, G.; Momany, Y.; de Marchi, F.; Recio-Blanco, A.

    2009-10-01

    Context: We present a photometric and astrometric catalog of 187 963 stars located in the field around the old super-metal-rich Galactic open cluster NGC 6253. The total field-of-view covered by the catalog is 34”×33”. In this field, we provide CCD BVRI photometry. For a smaller region close to the cluster's center, we also provide near-infrared JHK photometry. Aims: We analyze the properties of NGC 6253 by using our new photometric data and astrometric membership. Methods: In June 2004, we targeted the cluster during a 10 day multi-site campaign, which involved the MPG/ESO 2.2 m telescope with its wide-field imager and the Anglo-Australian 3.9 m telescope, equipped with the IRIS2 near-infrared imager. Archival CCD images of NGC 6253 were used to derive relative proper motions and to calculate the cluster membership probabilities. Results: We have refined the cluster's fundamental parameters, deriving (V_0-M_v)=11.15, E(B - V) = 0.15, E(V - I) = 0.25, E(V - J) = 0.50, and E(V - H) = 0.55. The color excess ratios obtained using both the optical and near infrared colors indicate a normal reddening law in the direction of NGC 6253. The age of NGC 6253 at 3.5 Gyr, determined from our best-fitting isochrone appears to be slightly older than the previous estimates. Finally, we estimated the binary fraction among the cluster members to be ~20%-30% and identified 11 blue straggler candidates. Based on observation made at the European Southern Observatory, La Silla, Chile and at the Anglo-Australian Observatory, Siding Spring, Australia. The catalog presented in this paper is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/505/1129

  15. Analysis of impact of Busch Gardens expansion on air quality of surrounding area

    NASA Technical Reports Server (NTRS)

    Kindle, E. C.; Maier, G.; Copeland, G. E.

    1975-01-01

    This report is concerned primarily with the increase in carbon monoxide concentrations and hydrocarbon concentrations induced by the projected increased traffic that would be associated with the parking facilities planned to support the expansion of Busch Gardens (Virginia) planned for the summar of 1976. Of primary concern is the integrated effect of the increased traffic that will be handled by existing facilities and an enlarged parking lot across the highway from the main Busch Garden attraction.

  16. Increasing impact of urban fine particles (PM2.5) on areas surrounding Chinese cities

    PubMed Central

    Han, Lijian; Zhou, Weiqi; Li, Weifeng

    2015-01-01

    The negative impacts of rapid urbanization in developing countries have led to a deterioration in urban air quality, which brings increasing negative impact to its surrounding areas (e.g. in China). However, to date there has been rare quantitative estimation of the urban air pollution to its surrounding areas in China.We thus evaluated the impact of air pollution on the surrounding environment under rapid urbanization in Chinese prefectures during 1999 – 2011. We found that: (1) the urban environment generated increasing negative impact on the surrounding areas, and the PM2.5 concentration difference between urban and rural areas was particularly high in large cities. (2) Nearly half of the Chinese prefectures (156 out of 350) showed increased impact of urban PM2.5 pollution on its surrounding areas. Those prefectures were mainly located along two belts: one from northeast China to Sichuan province, the other from Shanghai to Guangxi province. Our study demonstrates the deterioration in urban air quality and its potential impacts on its surrounding areas in China. We hope that the results presented here will encourage different approaches to urbanization to mitigate the negative impact caused by urban air pollution, both in China and other rapidly developing countries. PMID:26219273

  17. Attention reshapes center-surround receptive field structure in macaque cortical area MT.

    PubMed

    Anton-Erxleben, Katharina; Stephan, Valeska M; Treue, Stefan

    2009-10-01

    Directing spatial attention to a location inside the classical receptive field (cRF) of a neuron in macaque medial temporal area (MT) shifts the center of the cRF toward the attended location. Here we investigate the influence of spatial attention on the profile of the inhibitory surround present in many MT neurons. Two monkeys attended to the fixation point or to 1 of 2 random dot patterns (RDPs) placed inside or next to the cRF, whereas a third RDP (the probe) was briefly presented in quick succession across the cRF and surround. The probe presentation responses were used to compute a map of the excitatory receptive field and its inhibitory surround. Attention systematically reshapes the receptive field profile, independently shifting both center and surround toward the attended location. Furthermore, cRF size is changed as a function of relative distance to the attentional focus: attention inside the cRF shrinks it, whereas directing attention next to the cRF expands it. In addition, we find systematic changes in surround inhibition and cRF amplitude. This nonmultiplicative push-pull modulation of the receptive field's center-surround structure optimizes processing at and near the attentional focus to strengthen the representation of the attended stimulus while reducing influences from distractors. PMID:19211660

  18. Spatial offset of test field elements from surround elements affects the strength of motion aftereffects.

    PubMed

    Harris, John; Sullivan, Daniel; Oakley, Madeleine

    2008-01-01

    Static movement aftereffects (MAEs) were measured after adaptation to vertical square-wave luminance gratings drifting horizontally within a central window in a surrounding stationary vertical grating. The relationship between the stationary test grating and the surround was manipulated by varying the alignment of the stationary stripes in the window and those in the surround, and the type of outline separating the window and the surround [no outline, black outline (invisible on black stripes), and red outline (visible throughout its length)]. Offsetting the stripes in the window significantly increased both the duration and ratings of the strength of MAEs. Manipulating the outline had no significant effect on either measure of MAE strength. In a second experiment, in which the stationary test fields alone were presented, participants judged how segregated the test field appeared from its surround. In contrast to the MAE measures, outline as well as offset contributed to judged segregation. In a third experiment, in which test-stripe offset was systematically manipulated, segregation ratings rose with offset. However, MAE strength was greater at medium than at either small or large (180 degrees phase shift) offsets. The effects of these manipulations on the MAE are interpreted in terms of a spatial mechanism which integrates motion signals along collinear contours of the test field and surround, and so causes a reduction of motion contrast at the edges of the test field. PMID:18773724

  19. Surrounding greenness, proximity to city parks and pregnancy outcomes in Kaunas cohort study

    PubMed Central

    Grazuleviciene, Regina; Danileviciute, Asta; Dedele, Audrius; Vencloviene, Jone; Andrusaityte, Sandra; Uždanaviciute, Inga; Nieuwenhuijsen, Mark J.

    2015-01-01

    There is increasing evidence that green space can improve the health and well-being of urban residents. However, there has been no consistent evidence of the effect of city parks on reproductive health. We investigated whether surrounding greenness levels and/or distance to city parks affect birth outcomes. This study was based on 3292 singleton live-births from the Kaunas birth cohort, Lithuania (2007–2009), who were enrolled in the FP7 PHENOTYPE project study. Residential surrounding greenness level was ascertained as average of satellite-based normalized difference vegetation index (NDVI) within buffers of 100 m, 300 m, and 500 m of each maternal home and distance to a city park was defined as distance to boundaries of the nearest city park. For each indicator of green space exposure, linear or logistic regression models were constructed to estimate change in birth outcomes adjusted for relevant covariates. An increase in distance to a city parks was associated with an increase in risk of preterm birth and decrease of gestational age. We found a statistically significant association between low surrounding greenness and term low birth weight. After assessing effect modification based on the low surrounding greenness (NDVI-500 < median) and the distance to city parks (>1000 m), we found increased risks for low birth weight (OR 2.23, 1.20–4.15), term low birth weight (OR 2.97, 1.04–8.45) and preterm birth (OR 1.77, 1.10–2.81) for subjects with low surrounding greenness and farther distance from a park. Both higher surrounding greenness level and proximity to park have beneficial effects on pregnancy outcomes. A beneficial park effect on foetal growth is most apparent in the environment with low surrounding greenness level. Further investigation is needed to confirm this association. PMID:25757723

  20. Effect of a Surrounding Liquid Environment on the Electrical Disruption of Pendant Droplets.

    PubMed

    Mohamed, A Said; Lopez-Herrera, Jose M; Herrada, Miguel A; Modesto-Lopez, Luis B; Gañán-Calvo, Alfonso M

    2016-07-12

    The effect of a surrounding, dielectric, liquid environment on the dynamics of a suddenly electrified liquid drop is investigated both numerically and experimentally. The onset of stability of the droplet is naturally dictated by a threshold value of the applied electric field. While below that threshold the droplet retains its integrity, reaching to a new equilibrium state through damped oscillations (subcritical regime), above it electrical disruption takes place (supercritical regime). In contrast to the oscillation regime, the dynamics of the electric droplet disruption in the supercritical regime reveals a variety of modes. Depending on the operating parameters and fluid properties, a drop in the supercritical regime may result in the well-known tip streaming mode (with and without whipping instability), in droplet splitting (splitting mode), or in the development of a steep shoulder at the elongating front of the droplet that expands radially in a sort of "splashing" (splashing mode). In both splitting and splashing modes, the sizes of the progeny droplets, generated after the breakup of the mother droplet, are comparable to that of the mother droplet. Furthermore, the development in the emission process of the shoulder leading to the splashing mode is described as a parametrical bifurcation, and the parameter governing that bifurcation has been identified. Physical analysis confirms the unexpected experimental finding that the viscosity of the dynamically active environment is absent in the governing parameter. However, the appearance of the splitting mode is determined by the viscosity of the outer environment, when that viscosity overcomes a certain large value. These facts point to the highly nonlinear character of the drop fission process as a function of the droplet volume, inner and outer liquid viscosities, and applied electric field. These observations may have direct implications in systems where precise control of the droplet size is critical, such

  1. Variation of fundamental mode Rayleigh wave group velocity dispersion in Iran and the surrounding region

    NASA Astrophysics Data System (ADS)

    Rham, D.; Priestley, K.; Tatar, M.; Paul, A.; Hatzfeld, D.; Radjaee, A.; Nowrouzi, G.; Kaviani, A.; Tiberi, C.

    2005-12-01

    We present group velocity dispersion results from a study of regional fundamental mode Rayleigh waves propagating across Iran and the surrounding region. Data for these measurements come from field deployments within Iran by the University of Cambridge (UK) and the Universite Joseph-Fourier (FRA) in conjunction with International Institute of Earthquake Engineering and Seismology (Iran), within Oman by the Universite Pierre et Marie Curie-Paris (FRA), in addition to data from IRIS and Geofone. 1D path-averaged dispersion measurements have been made for ~800 source-receiver paths using multiple filter analysis. We combine these observations in a tomographic inversion to produce group velocity images between 15 and 60~s period. Because of the dense path coverage, these images have substantially higher lateral resolution for this region than is currently available from global and regional group velocity studies. We observe variations in short-period group velocity which is consistent with the surface geology. Low group velocity (2.45-2.55~km/s) at short periods (15-20~s) is observed beneath the south Caspian Basin, northern Iran, the Persian Gulf, the Zagros, the Makran, northern Afghanistan and southern Pakistan. Somewhat higher group velocity (2.60-2.70~km/s) at these periods occurs in central Iran. At intermediate periods (30-40~s) group velocities over most of the region are low (2.90-3.10~km/s) compared to Arabia. At longer periods (50-60~s) group velocities remain low (3.35-3.45~km/s) over most of Iran but there is a suggestion of higher group velocities beneath the northern and central Zagros.

  2. Irradiation of Population in the Surrounding Area of Nuclear Power Plant Temelin

    SciTech Connect

    Thinova, Lenka; Kluson, Jaroslav

    2008-08-07

    In monitoring the impact of nuclear facilities operation on ecosystem, it is necessary to consider, what part of biota irradiation can be caused by an artificial source. For the estimation of an effective dose from natural sources were used measurements of dosimetric and gamma spectrometric characteristics of photon fields, (performed in the area of NPP Temelin since year 2000) and data from the Czech Republic radiometric chart, including the results from radon volume activity measurements in dwellings. For gamma spectrometric measurements in situ were selected two methodologies and for measurement were used corresponding types of equipment (Tesla NB3201 and spectrometer NaI(TI) 3''x3'') at selected locations within the monitored area: i) determination of air kerma rate (through direct measurement and by calculationfrom spectrometric data); ii) measurement of photon spectra by an scintillating spectrometer. For a dose assessment from artificial sources resulting from past or present operation of NPP Temelin, were used records from all so far performed laboratory and field measurements of NPP releases, food baskets and also results of a 6 year ecosystem monitoring in the surrounding area of NPP Temelin. The ecosystem monitoring is based on studying the contamination of the following bioindicators: forest humus, Pine bark, Schreber's Moss, the Bay Bolete (mushroom) and forest berries. Each year 220 samples are collected and mass activity (Bq/kg) for eventual contaminants is determined using laboratory gamma spectroscopy. For measurements is used a coaxial HPGe detector, with samples in the geometry of 'Marinelli' container. For evaluation of the laboratory results obtained is used trend analysis. The above described monitoring has been performed from the year 2000 until now (the year 2000 is pre-operational). In all measured laboratory spectra, of all analyzed samples, were not identified any non-natural radionuclides, with the exception of {sup 137}Cs, for which

  3. Subepidermal moisture surrounding pressure ulcers in persons with a spinal cord injury: A pilot study

    PubMed Central

    Harrow, Jeffrey John; Mayrovitz, Harvey N.

    2014-01-01

    Objective Characterization of a non-invasive method of quantifying subepidermal moisture (SEM) surrounding stages III and IV pressure ulcers (PrUs) in spinal cord injury (SCI). Design Prospective, single-visit, single-rater, observational study, using repeated-measures analysis. Method Setting-inpatient units of one VA SCI Center. Participants Convenience sample of 16 subjects with SCI with stage III or IV PrUs over sacrum or ischium. Interventions Measurement with the MoistureMeter-D, a hand-held device using 300 MHz electromagnetic waves. Outcome measures Dielectric constant, a dimensionless number which increases with the moisture content. Each subject had a PrU site and a control site. Measurements were made at each site, on intact skin, at four points spaced angularly around the site, in triplicate. Results (1) Short-term, single-rater relative error was 2.5%. (2) Order effect: first readings were higher than second readings in 55 of 64 measurement sets. Order effect was significant for control sites (P < 0.0001) but not for PrU sites. (3) Angular effect: SEM varied by angle at the PrU sites (P < 0.01); 12 o'clock position the highest and 6 o'clock the lowest. (4) Ability to differentiate PrUs from intact skin: SEM at PrU sites was greater by 9.0% than control sites (P < 0.05). (5) Site effect: SEM was higher at sacral locations than ischial at control sites by 20% (P < 0.005). Conclusions SEM differentiates PrUs from intact skin. Future study designs must take into account order, angular, and site effects on this measure. This information will inform designers of future studies of SEM in healing of PrUs. PMID:25398030

  4. Origin and significance of deep earthquake clusters surrounding a pronounced seismic gap in northeast China

    NASA Astrophysics Data System (ADS)

    Gan, Wei; Frohlich, Cliff; Jin, Zhenmin

    2015-03-01

    From analysis of earthquakes in the Global centroid moment tensor (GCMT) catalog, we identify an intermediate depth (∼250-350 km) seismic gap having dimensions of ∼300 km × 500 km within the subducting northwestern Pacific plate (NPP), and surrounded by several groups of isolated earthquakes near northeast China. Normally, groups of unusual deep earthquakes may represent a detached slab segment, as in Tonga-Vanuatu; and a deep seismic gap maybe either be the aseismic continuation of a subducting slab or a possible gap in the subducting plate. We evaluate the characteristics of deep earthquakes in the NPP and focus on three isolated clusters, particularly one directly beneath the seismic gap and northeast China. This sub-gap cluster has a peak in the number of quakes near depth ∼580 km, unlike seismicity in the NPP as a whole. Its b-value (∼0.60) is significantly smaller than b-values in two other nearby clusters (∼0.81 and ∼0.86) in the NPP. Focal mechanisms in this sub-gap cluster also show a variation with depth, and projections of their T, P, and B axes differ from what is observed for the other isolated clusters. We speculate why these sub-gap earthquakes are isolated and suggest two possible models explaining the presence of the gap and the characteristics of the underlying cluster beneath northeast China. In the first model, the seismic gap is attributable to aseismic deformation caused by abnormally high temperatures in the subducting lithosphere. And, the characteristics of the sub-gap clusters and its related slab structures are attributed to slab buckling caused by resistance to subduction. In the second model, the seismic gap represents absent subducting lithosphere and the missing material has migrated to the bottom of subducting slab. Although we favor the second model, both models are consistent with our knowledge of deep earthquakes and the results of recent studies near northeast China.

  5. Two-Phase PIV: Fuel-Spray Interaction with Surrounding Air

    NASA Astrophysics Data System (ADS)

    Dankers, Stefan; Gotthardt, Mark; Stengler, Thomas; Ohmstede, Gerhard; Hentschel, Werner

    The demand for improvement of combustion-engine processes leads to a great need for detailed experimental information about the complicated processes of injection, breakup and propagation of the fuel jet and the vaporization of the fuel. Thus, in the presented work it was the aim to visualize the air flow that is induced by the injected fuel jet and also to explore the air entrainment into the fuel spray. This was done using two-phase PIV (particle image velocimetry). The fuel jet was illuminated with a Nd:YAG PIV-laser and PIV analysis was done by simply measuring the elastically scattered light of the fuel droplets. For the investigation of the surrounding air propylene-carbonate doped with DCM-dye was dispersed and the droplets were added to the continuous gas flow upstream of the chamber. Scattered and fluorescence signals, respectively, were detected perpendicular to the laser sheet with a CCD camera. To detect the gas flow, the scattered light from the liquid fuel was suppressed by an OG 590 longpass filter glass that transmits the fluorescence signal of the DCM-dye. It was possible to measure both the fuel jet and the gas flow in the presence of the fuel spray and a clear separation of the two phases could be achieved. In both (fuel and air) vector pictures corresponding vortices could be identified near the air/fuel boundary layer. Maximum velocities in the jet are depending on the operation conditions up to 150ms-1 and the gas flow has typically a velocity of 1 to 10ms-1. In the region next to the injector the air was pressed away during the injection. After the end of the injection a strong fast air entrainment flow into this region can be observed that compensates the pressure difference.

  6. Apparent Susceptibility Contrast Distribution of Continental Lithosphere in China and Its Surroundings: Implications to Regional Tectonics

    NASA Astrophysics Data System (ADS)

    Du, J.; Chen, C.; Sun, S.; Zhang, Y.; Liang, Q.

    2015-12-01

    Lithospheric magnetic field characterizes response of magnetic properties of rocks, which are mainly dependent on mineral and temperature variations. Hence, lithospheric magnetic structure brings important information to understand tectonic and thermal processes in the crust and uppermost mantle. In particular, the reliable global geomagnetic field models with large-scales based on satellite magnetic measurements provide regional view of the lithospheric magnetic structure. Here, with smallest and flattest constraints we use the inversion method based on the single layer model to calculate the spatial distribution of apparent susceptibility of continental lithosphere in China and its surroundings. It should be noted that: (1) magnetic anomaly data we used has removed the effect of global oceanic remanent magnetization, (2) the error of magnetic anomaly data is estimated from statistical analysis among MF7, GRIMM_L120, CHAOS5 and CM5 models, (3) the magnetic layer is bounded by the bottom of sediment and the Moho from CRUST1.0 model and is discretized into ellipsoidal prisms with equal angles in latitude and longitude, and (4) an adaptive subdivision & Gauss-Legendre quadrature with fixed order is adopted to solve the forward problem and IGRF11 is utilized as inducing field model. Since the missing longest wavelength components in the lithospheric magnetic field models and the so-called magnetic annihilators, the Apparent Susceptibility Contrast (ASC) distribution is obtained. The ASC distribution has obvious variations and illustrates the mosaic continent with old blocks, orogenic belts, rework fragments and also earthquake regions/zones. Moreover, the ASC distribution provides new insights and evidences of the destruction of North China Craton and geodynamic processes of Tibetan plateau and Baikal rift etc. This study is supported by China Postdoctoral Science Foundation (Grant No.: 2015M572217) and Natural Science Fund of Hubei Province (Grant No.: 2015CFB361).

  7. GRB 081007 AND GRB 090424: THE SURROUNDING MEDIUM, OUTFLOWS, AND SUPERNOVAE

    SciTech Connect

    Jin Zhiping; Covino, Stefano; Fugazza, Dino; Melandri, Andrea; Campana, Sergio; D'Avanzo, Paolo; Della Valle, Massimo; Ferrero, Patrizia; Malesani, Daniele; Fynbo, Johan P. U.; Hjorth, Jens; Pian, Elena; Salvaterra, Ruben; Bersier, David; Cano, Zach; Castro-Tirado, Alberto J.; Gorosabel, Javier; Guidorzi, Cristiano; Haislip, Joshua B.; and others

    2013-09-10

    We discuss the results of the analysis of multi-wavelength data for the afterglows of GRB 081007 and GRB 090424, two bursts detected by Swift. One of them, GRB 081007, also shows a spectroscopically confirmed supernova, SN 2008hw, which resembles SN 1998bw in its absorption features, while the maximum magnitude may be fainter, up to 0.7 mag, than observed in SN 1998bw. Bright optical flashes have been detected in both events, which allows us to derive solid constraints on the circumburst-matter density profile. This is particularly interesting in the case of GRB 081007, whose afterglow is found to be propagating into a constant-density medium, yielding yet another example of a gamma-ray burst (GRB) clearly associated with a massive-star progenitor which did not sculpt the surroundings with its stellar wind. There is no supernova component detected in the afterglow of GRB 090424, likely due to the brightness of the host galaxy, comparable to the Milky Way. We show that the afterglow data are consistent with the presence of both forward- and reverse-shock emission powered by relativistic outflows expanding into the interstellar medium. The absence of optical peaks due to the forward shock strongly suggests that the reverse-shock regions should be mildly magnetized. The initial Lorentz factor of outflow of GRB 081007 is estimated to be {Gamma} {approx} 200, while for GRB 090424 a lower limit of {Gamma} > 170 is derived. We also discuss the prompt emission of GRB 081007, which consists of just a single pulse. We argue that neither the external forward-shock model nor the shock-breakout model can account for the prompt emission data and suggest that the single-pulse-like prompt emission may be due to magnetic energy dissipation of a Poynting-flux-dominated outflow or to a dissipative photosphere.

  8. Characterisation by PIXE RBS of metallic contamination of tissues surrounding a metallic prosthesis on a knee

    NASA Astrophysics Data System (ADS)

    Guibert, G.; Irigaray, J. L.; Moretto, Ph.; Sauvage, T.; Kemeny, J. L.; Cazenave, A.; Jallot, E.

    2006-09-01

    Implants used as biomaterials have to fulfill conditions of functionality, compatibility and sometimes bioactivity. There are four main families of biomaterials: metals and metal alloys, polymers, bioceramics and natural materials. Because of corrosion and friction in the human body, implants generate debris. This debris may develop toxicity, inflammation and prosthetic unsealing by osseous dissolution. Nature, size, morphology and amount of debris are the parameters influencing the tissue responses. In this paper, we characterised metallic contamination produced by knee prosthesis, composed with TiAl 6V 4 or Co-Cr-Mo alloys, into surrounding capsular tissue by depth migration, in vivo behaviour, content, size and nature of debris by PIXE (Particle Induced X-ray Emission) method associated with RBS (Rutherford Backscattering Spectroscopy). Debris distribution in the whole articulation is very heterogeneous. Debris migrates several thousand micrometers in tissues, with a characteristic decrease. Solid metallic particles of about micrometer size are found in the most polluted samples, in both alloys TiAl 6V 4 and Cr-Co-Mo. In the mean volume analysed by PIXE, the concentration mass ratios [Ti]/[V] and [Co]/[Cr] confirm the chemical stability of TiAl 6V 4 debris and show the chemical evolution of Cr-Co-Mo debris. Development of a protocol to prepare thin targets permits us to correlate PIXE and histological analysis in the same zone. The fibrous tissue (collagen fibres, fibroblasts) and macrophage cells are observed with optical microscope in polluted areas. This protocol could locate other pathologies in ppm contamination range, thanks to the great sensitivity of the PIXE method.

  9. Interleukin (IL)-8 immunoreactivity of injured axons and surrounding oligodendrocytes in traumatic head injury.

    PubMed

    Hayashi, Takahito; Ago, Kazutoshi; Nakamae, Takuma; Higo, Eri; Ogata, Mamoru

    2016-06-01

    Interleukin (IL)-8 has been suggested to be a positive regulator of myelination in the central nervous system, in addition to its principal role as a chemokine for neutrophils. Immunostaining for beta-amyloid precursor protein (AβPP) is an effective tool for detecting traumatic axonal injury, although AβPP immunoreactivity can also indicate axonal injury due to hypoxic causes. In this study, we examined IL-8 and AβPP immunoreactivity in sections of corpus callosum obtained from deceased patients with blunt head injury and from equivalent control tissue. AβPP immunoreactivity was detected in injured axons, such as axonal bulbs and varicose axons, in 24 of 44 head injury cases. These AβPP immunoreactive cases had survived for more than 3h. The AβPP immunostaining pattern can be classified into two types: traumatic (Pattern 1) and non-traumatic (Pattern 2) axonal injuries, which we described previously [Hayashi et al. Int. J. Legal Med. 129 (2015) 1085-1090]. Three of 44 control cases also showed AβPP immunoreactive injured axons as Pattern 2. In contrast, IL-8 immunoreactivity was detected in 7 AβPP immunoreactive and in 2 non-AβPP immunoreactive head injury cases, but was not detected in any of the 44 control cases, including the 3 AβPP immunoreactive control cases. The IL-8 immunoreactive cases had survived from 3 to 24 days, whereas those cases who survived less than 3 days (n=29) and who survived 90 days (n=1) were not IL-8 immunoreactive. Moreover, IL-8 was detected as Pattern 1 axons only. In addition, double immunofluorescence analysis showed that IL-8 is expressed by oligodendrocytes surrounding injured axons. In conclusion, our results suggest that immunohistochemical detection of IL-8 may be useful as a complementary diagnostic marker of traumatic axonal injury. PMID:27065055

  10. Variability of accretion disks surrounding black holes: The role of inertial-acoustic mode instabilities

    NASA Technical Reports Server (NTRS)

    Chen, Xingming; Taam, Ronald E.

    1995-01-01

    The global nonlinear time-dependent evolution of the inertial-acoustic mode instability in accretion disks surrounding black holes has been investigated. The viscous stress is assumed to be proportional to the gas pressure only, i.e., tau = alphap(sub g). It is found that an oscillatory nonsteady behavior exists in the inner regions of disks (r is less than 10r(sub g) where r(sub g) is the Schwarzschild radius) for sufficiently large alpha(greater than or approximately equal to 0.2) and for mass accretion rates less than about 0.3 times the Eddington value. The variations of the integrated bolometric luminosity from the disk, Delta L/L, are less than 3%. A power spectrum analysis of these variations reveals a power spectrum which can be fitted to a power-law function of the frequency Pis proportional to f(exp -gamma), with index gamma = 1.4-2.3 and a low-frequency feature at about 4 Hz in one case. In addition, a narrow peak centered at a frequency corresponding to the maximum epicyclic frequency of the disk at approximately 100-130 Hz and its first harmonic is also seen. The low-frequency modulations are remarkably similar to those observed in black hole candidate systems. The possible existence of a scattering corona in the inner region of the disk and/or other processes contributing to the power at high frequencies in the inner region of the accretion disk may make the detection of the high-frequency component difficult.

  11. Protected areas and their surrounding territory: socioecological systems in the context of ecological solidarity.

    PubMed

    Mathevet, Raphaël; Thompson, John D; Folke, Carl

    2016-01-01

    The concept of ecological solidarity (ES) is a major feature of the 2006 law reforming national park policy in France. In the context of biodiversity conservation, the objectives of this study are to outline the historical development of ES, provide a working definition, and present a method for its implementation that combines environmental pragmatism and adaptive management. First, we highlight how ES provides a focus on the interdependencies among humans and nonhuman components of the socioecological system. In doing so, we identify ES within a framework that distinguishes ecological, socioecological, and sociopolitical interdependencies. In making such interdependencies apparent to humans who are not aware of their existence, the concept of ES promotes collective action as an alternative or complementary approach to state- or market-based approaches. By focusing on the awareness, feelings, and acknowledgement of interdependencies between actors and between humans and nonhumans, we present and discuss a learning-based approach (participatory modeling) that allows stakeholders to work together to construct cultural landscapes for present and future generations. Using two case studies, we show how an ES analysis goes beyond the ecosystem management approach to take into account how human interactions with the environment embody cultural, social, and economic values and endorse an ethically integrated science of care and responsibility. ES recognizes the diversity of these values as a practical foundation for socially engaged and accountable actions. Finally, we discuss how ES enhances academic support for a socioecological systems approach to biodiversity conservation and promotes collaboration with decision-makers and stakeholders involved in the adaptive management of protected areas and their surrounding landscapes. PMID:27039505

  12. Luobei graphite mines surrounding ecological environment monitoring based on high-resolution satellite data

    NASA Astrophysics Data System (ADS)

    Zhang, Lifeng; Liu, Xiaosha; Wan, Huawei; Liu, Xiaoman

    2014-11-01

    Graphite is one of the important industrial mineral raw materials, but the high content of heavy metals in tailings may cause soil pollution and other regional ecological environmental problems. Luobei has already become the largest production base of graphite. To find out the ecological situation in the region, further ecological risk analysis has been carried out. Luobei graphite mine which is located in Yabdanhe basin has been selected as the study area, SVM classifiers method with the support of GF-1 Satellite remote sensing data has been used, which is the first high-resolution earth observation satellite in China. The surrounding ecological environment was monitored and its potential impact on the ecological environment was analyzed by GIS platform. The results showed that the Luobei graphite mine located Yadanhe basin covers an area of 499.65 km2, the main types of forest ecosystems ( 44.05% of the total basin area ), followed by agricultural area( 35.14% ), grass area( 15.52% ), residential area ( 4.34% ), mining area ( 0.64% ) and water area( 0.30% ). By confirming the classification results, the total accuracy is 91.61%, the Kappa coefficient is 0.8991. Overall, GF-1 Satellite data can obtain regional ecosystems quickly, and provide a better data support for regional ecological resource protection zone. For Luobei graphite mines area, farmland and residential areas within its watershed are most vulnerable to mining, the higher proportion of farmland in duck river basin. The regulatory tailings need to be strengthened in the process of graphite mining processing.

  13. Micro-CT and histologic analyses of bone surrounding immediately loaded miniscrew implants: comparing compression and tension loading.

    PubMed

    Nakagaki, Susumu; Iijima, Masahiro; Handa, Keisuke; Koike, Toshiyuki; Yasuda, Yoshitaka; Saito, Takashi; Mizoguchi, Itaru

    2014-01-01

    This study investigated the effect of immediate force on bone adaptations surrounding miniscrew implants. Ten miniscrew implants were placed on the mandibles in three beagle dogs. Five pairs of miniscrew implants were immediately loaded with 150 g of continuous force using nickel-titanium coil springs for 8 weeks. The values of bone mineral density (BMD), bone mineral content (BMC), and bone volume (BV) of cortical and trabecular bone for compression loading and tension loading were obtained by µCT analysis. The percentages of bone-to-implant contact (BIC) in the compression and tension regions for cortical and trabecular bone were obtained by histologic analysis. The BMD values for the compression region of cortical bone were significantly higher compared to the tension region. The BIC values in cortical and trabecular bone at tension and compression regions were similar. In conclusion, immediate loading does not inhibit osseointegration of miniscrew implants but may stimulate bone mineralization. PMID:24583644

  14. Influence of surrounding structures upon the aerodynamic and acoustic performance of the outdoor unit of a split air-conditioner

    NASA Astrophysics Data System (ADS)

    Wu, Chengjun; Liu, Jiang; Pan, Jie

    2014-07-01

    DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structures upon the aerodynamic and acoustic performance, however they are only limited to the influence of a few parameters on the performance, and practical design of the unit requires more detailed parametric analysis. Three-dimensional computational fluid dynamics(CFD) and computational aerodynamic acoustics(CAA) simulation based on FLUENT solver is used to study the influence of surrounding structures upon the aforementioned properties of the unit. The flow rate and sound pressure level are predicted for different rotating speed, and agree well with the experimental results. The parametric influence of three main surrounding structures(i.e. the heat sink, the bell-mouth type shroud and the outlet grille) upon the aerodynamic performance of the unit is analyzed thoroughly. The results demonstrate that the tip vortex plays a major role in the flow fields near the blade tip and has a great effect on the flow field of the unit. The inlet ring's size and throat's depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. Furthermore, two improved schemes against the existing prototype of the unit are developed, which both can significantly increase the flow rate more than 6 %(i.e. 100 m3·h-1) at given rotating speeds. The inevitable increase of flow noise level when flow rate is increased and the advantage of keeping a lower rotating speed are also discussed. The presented work could be a useful guideline in designing the aerodynamic and acoustic performance of the split air-conditioner in engineering practice.

  15. Effects of surround suppression on response adaptation of V1 neurons to visual stimuli

    PubMed Central

    LI, Peng; JIN, Cai-Hong; JIANG, San; LI, Miao-Miao; WANG, Zi-Lu; ZHU, Hui; CHEN, Cui-Yun; HUA, Tian-Miao

    2014-01-01

    The influence of intracortical inhibition on the response adaptation of visual cortical neurons remains in debate. To clarify this issue, in the present study the influence of surround suppression evoked through the local inhibitory interneurons on the adaptation effects of neurons in the primary visual cortex (V1) were observed. Moreover, the adaptations of V1 neurons to both the high-contrast visual stimuli presented in the classical receptive field (CRF) and to the costimulation presented in the CRF and the surrounding nonclassical receptive field (nCRF) were compared. The intensities of surround suppression were modulated with different sized grating stimuli. The results showed that the response adaptation of V1 neurons decreased significantly with the increase of surround suppression and this adaptation decrease was due to the reduction of the initial response of V1 neurons to visual stimuli. However, the plateau response during adaptation showed no significant changes. These findings indicate that the adaptation effects of V1 neurons may not be directly affected by surround suppression, but may be dynamically regulated by a negative feedback network and be finely adjusted by its initial spiking response to stimulus. This adaptive regulation is not only energy efficient for the central nervous system, but also beneficially acts to maintain the homeostasis of neuronal response to long-presenting visual signals. PMID:25297081

  16. Precursor systems analyses of automated highway systems. Activity area I. Impact of AHS on surrounding non-AHS roadways. Final report, September 1993-November 1994

    SciTech Connect

    Lima, P.; Wert, A.; Crowe, E.; O`Brien, S.; Roper, D.

    1995-05-01

    The study considers the influence which automated highway system (AHS) traffic would have on the conventional, non-automated freeway and street system as it approaches and departs from the automated roadway. The higher speeds and capacities possible with an AHS facility will attract traffic into the AHS lane from both the general purpose freeway lanes and the parallel arterials. The increased AHS traffic will have both positive and negative impacts on the surrounding street system. The analysis includes the modeling and evaluation of the operations of a freeway corridor with and without an AHS lane. Operations with and without an AHS lane on the surrounding roadways are then evaluated using traffic operations measures of effectiveness. The surrounding roadways include the general purpose freeway lanes, freeway ramps, parallel arterials, and cross streets. Additional modeling analyzes the impact of the AHS traffic on the cross streets. The Highway Capacity Software (HCS) program is used to evaluate the level-of-service on alternative configurations of the cross streets and parallel arterials. The physical requirements of the AHS lane and ramps are analyzed to determine the impact on the surrounding streets. The modeling results are also used as input to the Activity P analysis. Qualitative as well as quantitative impacts are addressed. AHS is reviewed from the perspective of an urban planner.

  17. Category priming with aliens: analysing the influence of targets' prototypicality on the centre surround inhibition mechanism.

    PubMed

    Frings, Christian; Göbel, Ariane; Mast, Frank; Sutter, Julia; Bermeitinger, Christina; Wentura, Dirk

    2011-08-01

    Marginally perceptible prototypes as primes lead to slowed reactions to related category exemplars as compared to unrelated ones. This at first glance counterintuitive finding has been interpreted as evidence for a particular mechanism of lateral inhibition, namely the centre surround inhibition mechanism. We investigated the semantic surround of category labels by experimentally manipulating the prototypicality of stimuli. Participants first learned two new categories of fantasy creatures in a 5-day-long learning phase before they worked through a semantic priming task with the category prototypes as primes and category exemplars as targets. For high-prototypical targets we observed benefit effects from related primes, whereas for low-prototypical targets we observed cost effects. The results define when the centre surround inhibition mechanism is applied, and furthermore might explain why previous studies with word stimuli (i.e., material that prevents experimental manipulation of prototypicality) observed mixed results concerning the prototypicality of targets. PMID:21919586

  18. Linking Student Performance in Massachusetts Elementary Schools with the “Greenness” of School Surroundings Using Remote Sensing

    PubMed Central

    Wu, Chih-Da; McNeely, Eileen; Cedeño-Laurent, J. G.; Pan, Wen-Chi; Adamkiewicz, Gary; Dominici, Francesca; Lung, Shih-Chun Candice; Su, Huey-Jen; Spengler, John D.

    2014-01-01

    Various studies have reported the physical and mental health benefits from exposure to “green” neighborhoods, such as proximity to neighborhoods with trees and vegetation. However, no studies have explicitly assessed the association between exposure to “green” surroundings and cognitive function in terms of student academic performance. This study investigated the association between the “greenness” of the area surrounding a Massachusetts public elementary school and the academic achievement of the school’s student body based on standardized tests with an ecological setting. Researchers used the composite school-based performance scores generated by the Massachusetts Comprehensive Assessment System (MCAS) to measure the percentage of 3rd-grade students (the first year of standardized testing for 8–9 years-old children in public school), who scored “Above Proficient” (AP) in English and Mathematics tests (Note: Individual student scores are not publically available). The MCAS results are comparable year to year thanks to an equating process. Researchers included test results from 2006 through 2012 in 905 public schools and adjusted for differences between schools in the final analysis according to race, gender, English as a second language (proxy for ethnicity and language facility), parent income, student-teacher ratio, and school attendance. Surrounding greenness of each school was measured using satellite images converted into the Normalized Difference Vegetation Index (NDVI) in March, July and October of each year according to a 250-meter, 500-meter, 1,000-meter, and 2000-meter circular buffer around each school. Spatial Generalized Linear Mixed Models (GLMMs) estimated the impacts of surrounding greenness on school-based performance. Overall the study results supported a relationship between the “greenness” of the school area and the school-wide academic performance. Interestingly, the results showed a consistently positive significant

  19. Ultrafine particle concentrations in the surroundings of an urban area: comparing downwind to upwind conditions using Generalized Additive Models (GAMs).

    PubMed

    Sartini, Claudio; Zauli Sajani, Stefano; Ricciardelli, Isabella; Delgado-Saborit, Juana Mari; Scotto, Fabiana; Trentini, Arianna; Ferrari, Silvia; Poluzzi, Vanes

    2013-10-01

    The aim of this study was to investigate the influence of an urban area on ultrafine particle (UFP) concentration in nearby surrounding areas. We assessed how downwind and upwind conditions affect the UFP concentration at a site placed a few kilometres from the city border. Secondarily, we investigated the relationship among other meteorological factors, temporal variables and UFP. Data were collected for 44 days during 2008 and 2009 at a rural site placed about 3 kilometres from Bologna, in northern Italy. Measurements were performed using a spectrometer (FMPS TSI 3091). The average UFP number concentration was 11 776 (±7836) particles per cm(3). We analysed the effect of wind direction in a multivariate Generalized Additive Model (GAM) adjusted for the principal meteorological parameters and temporal trends. An increase of about 25% in UFP levels was observed when the site was downwind of the urban area, compared with the levels observed when wind blew from rural areas. The size distribution of particles was also affected by the wind direction, showing higher concentration of small size particles when the wind blew from the urban area. The GAM showed a good fit to the data (R(2) = 0.81). Model choice was via Akaike Information Criteria (AIC). The analysis also revealed that an approach based on meteorological data plus temporal trends improved the goodness of the fit of the model. In addition, the findings contribute to evidence on effects of exposure to ultrafine particles on a population living in city surroundings. PMID:24077061

  20. The physics of positively biased conductors surrounded by dielectrics in contact with a plasma

    NASA Technical Reports Server (NTRS)

    Hastings, Daniel E.; Chang, Patrick

    1989-01-01

    The physics of a positively biased conductor surrounded by dielectrics in contact with plasma is investigated. It is shown that because of the presence of secondary emission from the surrounding dielectrics, the voltage of the surfaces near the conductor has three solutions. The high- and low-voltage solutions are stable, while the intermediate-voltage solution is unstable. This theory is applied to explain the snapover effect observed on high-voltage solar arrays that involve the use of highly biased surfaces in contact with the space environment.

  1. Numerical modeling of Subthreshold region of junctionless double surrounding gate MOSFET (JLDSG)

    NASA Astrophysics Data System (ADS)

    Rewari, Sonam; Haldar, Subhasis; Nath, Vandana; Deswal, S. S.; Gupta, R. S.

    2016-02-01

    In this paper, Numerical Model for Electric Potential, Subthreshold Current and Subthreshold Swing for Junctionless Double Surrounding Gate(JLDSG) MOSFEThas been developed using superposition method. The results have also been evaluated for different silicon film thickness, oxide film thickness and channel length. The numerical results so obtained are in good agreement with the simulated data. Also, the results of JLDSG MOSFET have been compared with the conventional Junctionless Surrounding Gate (JLSG) MOSFET and it is observed that JLDSG MOSFET has improved drain currents, transconductance, outputconductance, Transconductance Generation Factor (TGF) and Subthreshold Slope.

  2. Impacts of Surrounding Land Cover on Headwater Wetland Edaphic Habitat Types and Their Associated Microbial Communities

    NASA Astrophysics Data System (ADS)

    Moon, J. B.; Wardrop, D. H.; Smithwick, E. A.

    2010-12-01

    Although small in size, headwater wetland complexes provide a disproportionate share of microbially mediated ecosystem services to the surrounding landscape and hydroscape. Two services that are of current interest to scientists and managers, given their role in regulating climate and water quality, are the retention and transformation of carbon and nitrogen pools. Although it is the wetland complex’s geographic position between the landscape and hydroscape that creates these hotspots of ecosystem function, continuous shifts in the surrounding scapes can also affect the complex’s transformational capacity through changes to its natural hydrologic disturbance regime and subsequent material fluxes. We have begun to investigate the influence of surrounding land cover and associated differences in hydrology on wetland edaphic habitats and their associated microbial communities. These studies are taking place in wetland complexes located in the headwaters of the Chesapeake Bay Watershed, within the Ridge and Valley Region of central Pennsylvania. Within this region, surrounding land cover ranges from intact forested buffers to a matrix of land cover types (e.g., mixed forest, grassland, and impermeable surfaces). Over a preliminary six-month collection period we found higher frequency and intensity of hydrologic fluctuations in wetlands surrounded by a matrix of land cover types, compared to highly stable saturated conditions of wetland complexes with intact forested buffers. Differences were also found in both the abundances of edaphic habitats as well as in the types of habitats present within these surrounding land cover groups. Wetlands with intact forested buffers had (1) fresh organic residue soils with high overall microbial biomasses and relatively high abundances of microeukaryotic groups, (2) reduced muck soils with relatively large proportions of branched fatty acid microbial groups, and (3) carbon and nutrient depleted sandy mineral soils with relatively

  3. Characterization and modeling of the cemented sediment surrounding the Iulia Felix glass

    SciTech Connect

    Strachan, Denis M.; Crum, Jarrod V.; Ryan, Joseph V.; Silvestri, Alberta

    2014-02-28

    About 1800 years ago a Roman Corbita sunk off the coast of Italy carrying a barrel of glass cullet to the floor of the Adriatic Sea. Samples of glass cullet and the cemented surrounding sediment have been characterized and the reaction between the glass and the sea water saturated with respect to calcite and dolomite has been modeled. Results from characterization and modeling show that the cement phase surrounding the sediment grains is a high-Mg calcite. The origin of the cement phase is likely the reaction between the glass and the sea water to from a Mg-silicate, here modeled as sepiolite.

  4. Abnormal surround inhibition does not affect asymptomatic limbs in people with cervical dystonia.

    PubMed

    McDougall, Laura; Kiernan, Dovin; Kiss, Zelma H T; Suchowersky, Oksana; Welsh, Timothy N

    2015-09-14

    Surround inhibition is a neural mechanism hypothesized to facilitate goal-directed action by disinhibiting agonist muscle activity while simultaneously inhibiting antagonist and other uninvolved muscle activity. The present study was designed to investigate if abnormalities in surround inhibition are found in asymptomatic body parts (the hand) of people with focal cervical dystonia (neck). Participants with (n=7) and without (n=17) cervical dystonia completed a protocol in which they abducted their index finger while EMG was recorded from the first dorsal interosseous (agonist) and abductor digiti minimi (uninvolved) muscles. Transcranial magnetic stimulation was delivered over the primary motor cortex at intervals ranging from 0 to 950+ms after the onset of agonist muscle activity. Motor-evoked potential (MEP) amplitudes from both muscles were compared. In control participants, MEPs from the uninvolved muscle were significantly lower than agonist MEPs at intervals from 0 to 480ms. Similarly, in the hands of participants with cervical dystonia - the asymptomatic body part - MEPs from the uninvolved muscle were significantly lower than agonist MEPs from 0 to 175ms. These findings suggest that surround inhibition in people with focal dystonia may be intact in asymptomatic hands. In other words, abnormalities in surround inhibition may be restricted to the dystonic limb. PMID:26219986

  5. Brief Report: Service Implementation and Maternal Distress Surrounding Evaluation Recommendations for Young Children Diagnosed with Autism

    ERIC Educational Resources Information Center

    Warren, Zachary; Vehorn, Alison; Dohrmann, Elizabeth; Newsom, Cassandra; Taylor, Julie Lounds

    2013-01-01

    There is limited evidence surrounding the ability of families of children with autism spectrum disorders to access and implement recommended interventions following diagnosis. The distress a family may encounter with regard to inability to access recommended services is also poorly understood. In this study, we present preliminary data regarding…

  6. INFLUENCE OF DEEP OCEAN SEWAGE OUTFALLS ON THE MICROBIAL ACTIVITY OF THE SURROUNDING SEDIMENT

    EPA Science Inventory

    The microbial activity near two deep ocean sewage outfalls off the coast of the island of Oahu, HI, was characterized. Water samples and sediment samples to a depth of 4.5 cm were analyzed from an area of approximately 4.5 x 10000 sq m surrounding the outfalls. Although the efflu...

  7. Roles of Frequency, Attitudes, and Multiple Intelligence Modality Surrounding Electricity Content-Based Reader's Theatre

    ERIC Educational Resources Information Center

    Hosier, Julie Winchester

    2009-01-01

    Integration of subjects is something elementary teachers must do to insure required objectives are covered. Science-based Reader's Theatre is one way to weave reading into science. This study examined the roles of frequency, attitudes, and Multiple Intelligence modalities surrounding Electricity Content-Based Reader's Theatre. This study used…

  8. GROUND WATER QUALITY SURROUNDING LAKE TEXOMA DURING SHORT-TERM DROUGHT CONDITIONS

    EPA Science Inventory

    Water quality data from 55 monitoring wells during drought conditions surrounding Lake Texoma, located on the border of Oklahoma and Texas, was compared to assess the influence of drought on groundwater quality. During the drought month of October, water table levels were three ...

  9. Family Concerns Surrounding Kindergarten Transition: A Comparison of Students in Special and General Education

    ERIC Educational Resources Information Center

    McIntyre, Laura Lee; Eckert, Tanya L.; Fiese, Barbara H.; Digennaro Reed, Florence D.; Wildenger, Leah K.

    2010-01-01

    Kindergarten transition is considered an important developmental milestone for children and families. Children with disabilities may be especially vulnerable during transition and may lack academic and behavioral readiness skills essential for kindergarten. Family concerns surrounding children's transition were explored in 132 students (n = 29…

  10. Students' Inventory of Social Actors Concerned by the Controversy Surrounding Cellular Telephones: A Case Study

    ERIC Educational Resources Information Center

    Pouliot, Chantal

    2008-01-01

    The present article scrutinizes the manner with which a group of three postsecondary students (in Quebec, Canada) describe the social actors concerned by the controversy surrounding cellular telephones. The study was conducted on the basis of an ethnographic approach. Participant observation was performed by the researcher for 3 hours during each…

  11. Apprenticeship for Teaching: Professional Development Issues Surrounding the Collaborative Relationship between Teachers and Paraeducators. Research Report.

    ERIC Educational Resources Information Center

    Rueda, Robert S.; Monzo, Lilia D.

    This report discusses findings from a study that examined issues surrounding the collaborative relationship between Latino paraeducators and the classroom teachers with whom they worked. Specifically, the study examined the types of activities that the paraeducators engaged in, the input they had in classroom instructional activities, the…

  12. Concentration Fluctuation in a Two-Component Fluid Membrane Surrounded with Three-Dimensional Fluids

    NASA Astrophysics Data System (ADS)

    Inaura, Keiichiro; Fujitani, Youhei

    2008-11-01

    We calculate the relaxation rate of the critical concentration fluctuation in a two-component fluid membrane by considering hydrodynamics of the surrounding fluids. Results are compared with the previous results obtained by Seki, Komura, and Imai (2007), who treated the momentum flux from the membrane to its environments using the friction coefficient.

  13. Greenhouse Effect: Temperature of a Metal Sphere Surrounded by a Glass Shell and Heated by Sunlight

    ERIC Educational Resources Information Center

    Nguyen, Phuc H.; Matzner, Richard A.

    2012-01-01

    We study the greenhouse effect on a model satellite consisting of a tungsten sphere surrounded by a thin spherical, concentric glass shell, with a small gap between the sphere and the shell. The system sits in vacuum and is heated by sunlight incident along the "z"-axis. This development is a generalization of the simple treatment of the…

  14. Gas Flux and Density Surrounding a Cylindrical Aperture in the Free Molecular Flow Regime

    NASA Technical Reports Server (NTRS)

    Soulas, George C.

    2011-01-01

    The equations for rigorously calculating the particle flux and density surrounding a cylindrical aperture in the free molecular flow regime are developed and presented. The fundamental equations for particle flux and density from a reservoir and a diffusely reflecting surface will initially be developed. Assumptions will include a Maxwell-Boltzmann speed distribution, equal particle and wall temperatures, and a linear flux distribution along the cylindrical aperture walls. With this information, the equations for axial flux and density surrounding a cylindrical aperture will be developed. The cylindrical aperture will be divided into multiple volumes and regions to rigorously determine the surrounding axial flux and density, and appropriate limits of integration will be determined. The results of these equations will then be evaluated. The linear wall flux distribution assumption will be assessed. The axial flux and density surrounding a cylindrical aperture with a thickness-to-radius ratio of 1.25 will be presented. Finally, the equations determined in this study will be verified using multiple methods.

  15. The Impact of Circumstances Surrounding the Death of a Child on Parents' Grief

    ERIC Educational Resources Information Center

    Wijngaards-de Meij, Leoniek; Stroebe, Margaret; Stroebe, Wolfgang; Schut, Henk; Van Den Bout, Jan; Van Der Heijden, Peter G. M.; Dijkstra, Iris

    2008-01-01

    A longitudinal study was conducted among bereaved parents to examine the relationship between the circumstances surrounding the death of their child and psychological adjustment. Two hundred nineteen couples participated at 6, 13, and 20 months post-loss. Examination was made of two categories of factors: those that were determined by the…

  16. Homogamy and Intermarriage of Japanese and Japanese Americans with Whites Surrounding World War II

    ERIC Educational Resources Information Center

    Ono, Hiromi; Berg, Justin

    2010-01-01

    Although some sociologists have suggested that Japanese Americans quickly assimilated into mainstream America, scholars of Japanese America have highlighted the heightened exclusion that the group experienced. This study tracked historical shifts in the exclusion level of Japanese and Japanese Americans in the United States surrounding World War…

  17. Developmental Changes during Childhood in Single-Letter Acuity and Its Crowding by Surrounding Contours

    ERIC Educational Resources Information Center

    Jeon, Seong Taek; Hamid, Joshua; Maurer, Daphne; Lewis, Terri L.

    2010-01-01

    Crowding refers to impaired target recognition caused by surrounding contours. We investigated the development of crowding in central vision by comparing single-letter and crowding thresholds in groups of 5-year-olds, 8-year-olds, 11-year-olds, and adults. The task was to discriminate the orientation of a Sloan letter E. Single-letter thresholds,…

  18. Effect of surround WP on behavior and mortality of the apple maggot (Diptera: Tephritidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The apple maggot fly, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), is a key pest in apple production areas located in the northeastern and midwestern United States and the eastern provinces of Canada. The development of Surround WP has offered a new approach for controlling apple maggot fly...

  19. The Perceived and Built Environment Surrounding Urban Schools & Physical Activity among Adolescent Girls

    PubMed Central

    Hager, Erin R.; Witherspoon, Dawn; Gormley, Candice; Latta, Laura; Pepper, M. Reese; Black, Maureen M.

    2013-01-01

    Background Neighborhood perceived/built environment and physical activity (PA) associations have been examined for adolescents around homes, but not surrounding schools. Purpose To examine if positive perceptions/built environment in neighborhoods surrounding schools predict PA among low-income, urban adolescent girls. Methods Measures include: minutes in moderate-vigorous PA (MVPA, ankle accelerometry), perceptions of the school environment (questionnaire), built environment (neighborhood audit). Analyses include multi-level models. Results 224 6th and 7th grade girls [mean(sd) age=12.1(0.7) years] from 12 schools serving low-income, primarily African American communities; mean MVPA 35.4minutes (mean days assessed=5.8). Girls in schools with more positive perceptions of the neighborhood environment surrounding the school were less active (β=7.2,p=0.043). Having “places to go within walking distance” (perceptions) and number of food stores near school (built environment) positively relate to MVPA (β=5.5,p=0.042 and β=0.59,p=0.047). Conclusions Among neighborhoods surrounding urban schools, positive perceptions do not predict PA; accessibility, via both perceived and built environment, support PA. PMID:23334761

  20. Roles of frequency, attitudes, and multiple intelligence modality surrounding Electricity Content-Based Reader's Theatre

    NASA Astrophysics Data System (ADS)

    Hosier, Julie Winchester

    Integration of subjects is something elementary teachers must do to insure required objectives are covered. Science-based Reader's Theatre is one way to weave reading into science. This study examined the roles of frequency, attitudes, and Multiple Intelligence modalities surrounding Electricity Content-Based Reader's Theatre. This study used quasi-experimental, repeated measures ANOVA with time as a factor design. A convenience sample of two fifth-grade classrooms participated in the study for eighteen weeks. Five Electricity Achievement Tests were given throughout the study to assess students' growth. A Student Reader's Theatre Attitudinal Survey revealed students' attitudes before and after Electricity Content-Based Reader's Theatre treatment. The Multiple Intelligence Inventory for Kids (Faris, 2007) examined whether Multiple Intelligence modality played a role in achievement on Electricity Test 4, the post-treatment test. Analysis using repeated measures ANOVA and an independent t-test found that students in the experimental group, which practiced its student-created Electricity Content-Based Reader's Theatre skits ten times versus two times for the for control group, did significantly better on Electricity Achievement Test 4, t(76) = 3.018, p = 0.003. Dependent t-tests did not find statistically significant differences between students' attitudes about Electricity Content-Based Reader's Theatre before and after treatment. A Kruskal-Wallis test found no statistically significant difference between the various Multiple Intelligence modalities score mean ranks (x2 = 5.57, df = 2, alpha = .062). Qualitative data do, however, indicate students had strong positive feelings about Electricity Content-Based Reader's Theatre after treatment. Students indicated it to be motivating, confidence-building, and a fun way to learn about science; however, they disliked writing their own scripts. Examining the frequency, attitudes, and Multiple Intelligence modalities lead to

  1. Physical cell interactions with their surrounding materials: Mechanics and geometrical factors using microfluidic platforms

    NASA Astrophysics Data System (ADS)

    Lopez Garcia, Maria Del Carmen

    Microfluidics platforms are employed in: "sperm motion in a microfluidic device" and "mechanical interactions of mammary gland cells with their surrounding three dimensional extra-cellular matrix". Microfluidics has shown promise as a new platform for assisted reproduction. Sperm and fluid motion in microchannels was studied to understand the flow characteristics in the device, how sperm interacted with this flow, and how sperm-oocyte attachment occurs in the device. A threshold fluid velocity was found where sperm transition from traveling with the fluid to a regime in which they can move independently. A population of sperm remained in the inlet well area. There was also the tendency of sperm to travel along surface contours. These observations provide an improved understanding of sperm motion in microchannels and a basis for improved device designs. The effort to understand the development of breast cancer motivates the study of mammary gland cells and their interactions with the extra-cellular matrix. Mammographic density is a risk factor for breast cancer which correlates with collagen density affects cell behavior. Collagen gels with concentrations of 1.3, 2, and 3 mg/mL, were tensile tested to obtain the Young's modulus, E, at low displacement rates of 0.01, 0.1, and 1 mm/min. Local strain measurement in the gage section were used for both strain and strain rate determination. Local strain rates were on the order of cellular generated strain rate. A power law fitting described the relationship between Young's modulus and local strain rate. Mammary gland cells were seeded with collagen and fluorescent beads into microchannels and observed via four-dimensional imaging. The displacements of the beads were used to calculate strains. The Young's modulus due to the rate at which the cell was straining the collagen was obtained from the aforementioned fittings. Three-dimensional elastic theory for an isotropic material was employed to calculate the stress. The

  2. Holocene coastal and palaeoenvironmental evolution in the surroundings of the Rioni Delta (Kolkheti lowlands, W Georgia)

    NASA Astrophysics Data System (ADS)

    Laermanns, Hannes; Kelterbaum, Daniel; Elashvili, Mikheil; May, Matthias; Opitz, Stephan; Hülle, Daniela; Rölkens, Julian; Brückner, Helmut

    2016-04-01

    0.0.1 The Kolkheti (Colchis) lowlands form the central part of the extensive coastal lowlands along the Black Sea coast of Georgia. Situated between the Greater and the Lesser Caucasus, favourable climatic conditions resulted in a constant human occupation of the region during the Holocene. However, due to continuous deltaic sedimentation and progradation of the Rioni River, considerable changes of the coastal configuration and the palaeoenvironmental conditions in its hinterland are considered, which also were related to sea-level fluctuations of the Black Sea and modifications in sediment supply. Because there is a paucity of data regarding the Holocene coastal evolution of Western Georgia, this study aims to (i) determine the stratigraphy of the Kolkheti lowlands; (ii) elucidate the palaeogeographical and palaeoenvironmental changes along the Georgian Black Sea coastline; and (iii) reconstruct the (relative) sea-level (RSL) evolution in the study area, and compare these results with other regional studies. 0.0.2 Our research is based on ten sediment cores and two sediment outcrops which from the northern part of the Rioni delta area, i.e. the northern part of the Kolkheti lowlands. The sediment cores were analysed for geochemical and geophysical parameters (X-ray fluorescence spectroscopy, granulometry, loss on ignition, CN analysis) and for their microfaunal content (foraminifera, ostracoda), in order to deduce different depositional environments and their succession throughout the Holocene. The chronostratigraphy is based on 13 14C and 4 IRSL ages. Our results show that significant palaeoenvironmental changes have taken place in the surroundings of the Rioni delta during the last eight millennia. The sedimentary record indicates shallow marine conditions dominating most of the research area during the 6th millennium BC. These deposits are covered by brackish/lagoonal sediments. Lateron and floodplain-related fine-grained alluvial deposits accumulated since the

  3. THE EMISSION NEBULA Sh 2-174: A RADIO INVESTIGATION OF THE SURROUNDING REGION

    SciTech Connect

    Ransom, R. R.; Kothes, R.; Geisbuesch, J.; Landecker, T. L.; Reich, W.

    2015-02-01

    Sh 2-174 is believed to be either a planetary nebula (PN) or ionized, ambient interstellar medium (ISM). We present in this paper 1420 MHz polarization, 1420 MHz total intensity (Stokes-I), and neutral hydrogen (H I) images of the region around Sh 2-174. The radio images address not only the nature of the object, but also the history of the relationship between Sh 2-174 and its surrounding environment. The H I images show that Sh 2-174 sits presently at the center of a ∼1.°2 × ∼0.°4 cloud (with peak hydrogen density n {sub H} = 4 ± 2 cm{sup –3}). The Stokes-I image shows thermal-emission peaks (with electron densities n{sub e} = 11 ± 3 cm{sup –3}) coincident with the R-band optical nebula, as well as low-surface-brightness emission from an ionized ''halo'' around Sh 2-174 and from an ionized ''plateau'' extending southeast from the cloud. The polarization images reveal Faraday-rotation structures along the projected trajectory of Sh 2-174, including a high-contrast structure with ''arms'' that run precisely along the eastern edge of the H I cloud and a wide central region that merges with the downstream edge of Sh 2-174. The high-contrast structure is consistent with an ionized tail that has both early-epoch (before Sh 2-174 entered the cloud) and present-epoch (after Sh 2-174 entered the cloud) components. Furthermore, our rotation-measure analysis indicates that the ISM magnetic field is deflected at the leading edge of Sh 2-174. The downstream tail and upstream field deflection point to a PN-ISM interaction. Our estimated space velocity for the host white dwarf (GD 561) demonstrates that Sh 2-174 entered the cloud ∼27,000 yr ago, and gives a PN-ISM interaction timescale ≲ 2.0 × 10{sup 5} yr. We estimate an ambient magnetic field in the cloud of 11 ± 3 μG.

  4. Crustal thickness and images of the lithospheric discontinuities in the Gibraltar arc and surrounding areas

    NASA Astrophysics Data System (ADS)

    Mancilla, Flor de Lis; Stich, Daniel; Morales, José; Martín, Rosa; Diaz, Jordi; Pazos, Antonio; Córdoba, Diego; Pulgar, Javier A.; Ibarra, Pedro; Harnafi, Mimoun; Gonzalez-Lodeiro, Francisco

    2015-12-01

    The Gibraltar arc and surrounding areas are a complex tectonic region and its tectonic evolution since Miocene is still under debate. Knowledge of its lithospheric structure will help to understand the mechanisms that produced extension and westward motion of the Alboran domain, simultaneously with NW-SE compression driven by Africa-Europe plates convergence. We perform a P-wave receiver function analysis in which we analyse new data recorded at 83 permanent and temporary seismic broad-band stations located in the South of the Iberian peninsula. These data are stacked and combined with data from a previous study in northern Morocco to build maps of thickness and average vP/vS ratio for the crust, and cross-sections to image the lithospheric discontinuities beneath the Gibraltar arc, the Betic and Rif Ranges and their Iberian and Moroccan forelands. Crustal thickness values show strong lateral variations in the southern Iberia peninsula, ranging from ˜19 to ˜46 km. The Variscan foreland is characterized by a relatively flat Moho at ˜31 km depth, and an average vP/vS ratio of ˜1.72, similar to other Variscan terranes, which may indicate that part of the lower crustal orogenic root was lost. The thickest crust is found at the contact between the Alboran domain and the External Zones of the Betic Range, while crustal thinning is observed southeastern Iberia (down to 19 km) and in the Guadalquivir basin where the thinning at the Iberian paleomargin could be still preserved. In the cross-sections, we see a strong change between the eastern Betics, where the Iberian crust underthrusts and couples to the Alboran crust, and the western Betics, where the underthrusting Iberian crust becomes partially delaminated and enters into the mantle. The structures largely mirror those on the Moroccan side where a similar detachment was observed in northern Morocco. We attribute a relatively shallow strong negative-polarity discontinuity to the lithosphere-asthenosphere boundary

  5. Toxicity of sediments surrounding the Gunpowder Neck Superfund Site at Aberdeen Proving Ground, Maryland. Final report, August 1992-December 1993

    SciTech Connect

    Haley, M.V.; Anthony, J.S.; Chester, N.A.; Kurnas, C.W.

    1995-07-01

    From the late 1940s through the 1960s, the standard practice for disposing of toxic chemicals at Aberdeen Proving Ground, MD, was open burning. This disposal site has since been placed on the National Priority List (NPt) by U.S. Environmental Protection Agency. In the spring 1992, sediment samples were taken from waterways that surround that disposal area. Chemical analysis and sediment toxicity assays (Ampelisca abdita) were conducted. Toxicity comparison, with sediment leachate from an Adapted Toxicity Characteristic teaching Procedure (ATCLP), were made using Daphnia magna and a fluorescent bacterium Photobacterium phosphoreum in MICROTOX assays. Amphipods showed a wide range of mortality in mud as well as coarser sediments indicating substrate preference is not critical to the outcome of the assay. Toxicity results from the leachates showed the sediments were not toxic to daphnia and MICROTOX assays.

  6. Isolation of a sesquiterpene synthase expressing in specialized epithelial cells surrounding the secretory cavities in rough lemon (Citrus jambhiri).

    PubMed

    Uji, Yuya; Ozawa, Rika; Shishido, Hodaka; Taniguchi, Shiduku; Takabayashi, Junji; Akimitsu, Kazuya; Gomi, Kenji

    2015-05-15

    Volatile terpenoids such as monoterpenes and sesquiterpenes play multiple roles in plant responses and are synthesized by terpene synthases (TPSs). We have previously isolated a partial TPS gene, RlemTPS4, that responds to microbial attack in rough lemon. In this study, we isolated a full length RlemTPS4 cDNA from rough lemon. RlemTPS4 localized in the cytosol. The recombinant RlemTPS4 protein was obtained using a prokaryotic expression system and GC-MS analysis of the terpenes produced by the RlemTPS4 enzymatic reaction determined that RlemTPS4 produces some sesquiterpenes such as δ-elemene. The RlemTPS4 gene was specifically expressed in specialized epithelial cells surrounding the oil secretory cavities in rough lemon leaf tissue. PMID:25899729

  7. The human health impact of Nyiragongo and Nyamulagira eruptions on Goma city and its surrounding area

    NASA Astrophysics Data System (ADS)

    Michellier, C.; Dramaix, M.; Arellano, S. R.; Kervyn, F.; Kahindo, J. B.

    2012-04-01

    of higher health risk for the population living under the plume. Additionally, time series analysis helps us to disregard any seasonal effect of certain pathologies and to derive a 12-year risk trend. For 2004-2010, our results are compared to SO2 gas emission rates and plume location data measured by using Differential Optical Absorption Spectroscopic (DOAS) sensors located around Nyiragongo volcano. Finally, the areas identified as more hazardous are highlighted through a geographical approach (using GIS tools), to generate maps and other relevant information that can be of direct use for risk assessment authorities. Our preliminary analysis suggests that the impact of SO2 emissions doesn't seem to be severe, being its most important effect an increase of ARI in the area surrounding the volcanoes (up to 50km). Our on-going study will help us to better determine the magnitude and geographical extent of the impact of volcanic plumes on the health of the population, as well as locate the areas that are most affected. This will contribute to provide the appropriate sanitation recommendations (water treatment, early warning system, etc.) and lead to a more effective volcanic impact reduction on human health.

  8. Tectonic implications of flexural modeling of the Uinta Mountains and surrounding basins since early Eocene time

    NASA Astrophysics Data System (ADS)

    Ratigan, D.; Heller, P.; Trampush, S. M.; Chen, P.; Dueker, K.

    2012-12-01

    across southern Wyoming is an order of magnitude higher, and across Utah is an order of magnitude lower, than previous estimates based on analysis of Cretaceous deflections, suggesting possible changes in rigidity through time. In addition, assuming lakes in the Uinta and Green River basins were connected at the time of deposition of the paleodatum, the difference in present elevation of the inflection point of the subsidence profiles suggests that there has been a net isostatic offset between the two basins. The origins of this offset might be due to regional isostatic differences from lithospheric density contrasts. Future work will include 3-D flexural modeling across all of the basins surrounding the Uinta Mountains, including the Piceance Creek, Sand Wash, and Washakie Basins.

  9. Assessing the completeness of historical earthquake records in Austria and surrounding Central Europe

    NASA Astrophysics Data System (ADS)

    Nasir, Asma; Lenhardt, Wolfgang; Hintersberger, Esther; Decker, Kurt

    2010-05-01

    formula for each country. In order to get the completeness periods for various magnitude ranges, the combined catalogue as well as each subcatalogue have been analyzed following the method of Stepp (1972). We can show that the new composite catalogue fulfills the critical minimum observation period for all intensity classes except IX and higher. A stable estimate of mean recurrence period of intensity IV is 80 years of homogeneous observations from 1900 to 1980 and for intensity V, the observation period is 120 years. A stable estimate of mean recurrence period for intensity VI is about 115 years and for intensity vii is 30 years. The homogeneous interval for maximum intensity VIII is 200 years. Maximum intensity IX earthquakes are not completely definitive for whole 962 years period. In addition, the analysis of each subcatalogue leads to similar results, except the ACORN catalogue. Therefore, the newly complied catalogue for Austria and surrounding areas is a suitable data base for seismic hazard assessment in Austria. References: ACORN, 2004, Catalogue of Earthquakes in the Region of the Alps - Western Carpathians - Bohemian Massif for the period from 1267 to 2004, Computer File, Vienna (Central Institute for Meteorology and Geodynamics, Department of Geophysics) - Brno (Institute of Physics of the Earth, University Brno). Van Gils, J.M. and G. Leydecker (1991): Catalogue of European earthquakes with intensities higher than 4. -- Commission of the European Communities - nuclear science and technology. 353 pp., 14 fig., 1 tab.- ISBN 92-826-2506-0, Catalogue number: CD-NA-13406-EN-C. Brussels - Luxembourg 1991. Shebalin, N. V., Leydecker, G., et al. (1998): Earthquake Catalogue for Central and Southeastern Europe 342 BC - 1990 AD. -- European Commission, Report No. ETNU CT 93 - 0087, Brussels. Stepp, J.C., 1972. Analysis of completeness of the earthquake sample in the Puget Sound area and its effect on statistical estimates of earthquake hazard. Proc. of the 1st Int

  10. Geographic Variation in Rosiglitazone Use Surrounding FDA Warnings in the Department of Veterans Affairs

    PubMed Central

    Ahuja, Vishal; Sohn, Min-Woong; Birge, John R.; Syverson, Chad; Budiman-Mak, Elly; Emanuele, Nicholas; Cooper, Jennifer M.; Huang, Elbert S.

    2016-01-01

    BACKGROUND Geographic variation in the use of prescription drugs, particularly those deemed harmful by the FDA, may lead to variation in patient exposure to adverse drug events. One such drug is the glucose-lowering drug rosiglitazone, for which the FDA issued a safety alert on May 21, 2007, following the publication of a meta-analysis that suggested a 43% increase in the risk of myocardial infarction with the use of rosiglitazone. This alert was followed by a black box warning on August 14, 2007, that was updated 3 months later. While large declines have been documented in rosiglitazone use in clinical practice, little is known about how the use of rosiglitazone and other glucose-lowering drugs varied within the Department of Veterans Affairs (VA), surrounding the FDA alerts. Understanding this variation within integrated health care systems is essential to formulating policies that enhance patient protection and quality of care. OBJECTIVE To document variation in the use of rosiglitazone and other glucose-lowering drugs across 21 Veterans Integrated Service Networks (VISNs). METHODS We conducted a retrospective analysis of drug use patterns for all major diabetes drugs in a national cohort of 550,550 veterans with diabetes from 2003 to 2008. This included the time periods when rosiglitazone was added to (November 2003) and removed from (October 2007) the VA national formulary (VANF). We employed multivariable logistic regression models to statistically estimate the association between a patient’s location and the patient’s odds of using rosiglitazone. RESULTS Aggregate rosiglitazone use increased monotonically from 7.7%, in the quarter it was added to the VANF (November 4, 2003), to a peak of 15.3% in the quarter when the FDA issued the safety alert. Rosiglitazone use decreased sharply afterwards, reaching 3.4% by the end of the study period (September 30, 2008). The use of pioglitazone, another glucose-lowering drug in the same class as rosiglitazone, was

  11. New geological and tectonic findings on the Ganos Fault and surroundings, NW Turkey

    NASA Astrophysics Data System (ADS)

    Ćinar, Seray; Zeki Tutkun, Salih; Özden, Süha; Kapan Yeşilyurt, Sevinç; Ateş, Özkan

    2010-05-01

    Ganos Fault, is a right lateral strike-slip fault, presented the western segment of the dextral North Anatolian Fault and has about 100 km long. It is namely Gaziköy-Saros segment and connects the western Marmara and Aegean Sea in Saros Gulf in continent. Ganos Fault is very active in both historical and instrumental period. Historical period earthquakes (M>6) occurred in 542, 824, 1063, 1343, 1344, 1354, 1542 and 1766. Besides in last century, 1912 Mürefte (M=7,3) Earthquake occurred on the Ganos Fault was the greatest and destructive. The aim of this study is present to new findings on geological and tectonics of Ganos Fault and surroundings. In this area, Lower-Middle Eocene aged Gaziköy Formation, as the basement unit, consists of sandstone-siltstone-shale and tuffit exposures as incline to north at the north of the Ganos Fault. It also observed with WSW-ENE direction in anticline at the southern part of the fault in Gazikoy Formation. Lower-Middle Miocene aged formations of Çanakkale Group overlie with angular unconformity on the Gaziköy Formation. Çanakkale Group consists of Gazhanedere and Kirazlı Formations. They appear lateral bedding and vertical transition in the region. Sandstones located at upper part of Kirazlı Formation and include Avimactra fossils. Although the Kirazlı Formation has aged Late Miocene in the previous studies, upper part of the formation firstly aged as Late Pliocene (Aktschagylian) according to Avimactra venjukovi (Andrussow), Avimactra ososkovi (Andrussow), Avimactra karabugasica (Andrussow) ve Avimactra subcaspia (Andrussow) in this study. This Aktschagylian aged lithology is cutting by the Ganos Fault and also has a tectonically contact with Eocene aged unit. This shows that the strike-slip deformation starts in Late Miocene and continues in Late Pliocene at least. In the study area, the youngest formation is marine terraces which located about 40 m. above sea level around Gaziköy village. This terrace consists of poor

  12. Experience-dependent specialization of receptive field surround for selective coding of natural scenes.

    PubMed

    Pecka, Michael; Han, Yunyun; Sader, Elie; Mrsic-Flogel, Thomas D

    2014-10-22

    At eye opening, neurons in primary visual cortex (V1) are selective for stimulus features, but circuits continue to refine in an experience-dependent manner for some weeks thereafter. How these changes contribute to the coding of visual features embedded in complex natural scenes remains unknown. Here we show that normal visual experience after eye opening is required for V1 neurons to develop a sensitivity for the statistical structure of natural stimuli extending beyond the boundaries of their receptive fields (RFs), which leads to improvements in coding efficiency for full-field natural scenes (increased selectivity and information rate). These improvements are mediated by an experience-dependent increase in the effectiveness of natural surround stimuli to hyperpolarize the membrane potential specifically during RF-stimulus epochs triggering action potentials. We suggest that neural circuits underlying surround modulation are shaped by the statistical structure of visual input, which leads to more selective coding of features in natural scenes. PMID:25263755

  13. Effects of fluorine emission on agricultural products surrounding an aluminum factory

    SciTech Connect

    Muramoto, S.; Nishizaki, H.; Aoyama, I. )

    1991-06-01

    The F concentrations of precipitate dust, agricultural products, and fingernail and hair at the surrounding Al factory were investigated. The F content of dust ranged from 15400 to 42500 micrograms/g dry weight, 190,000 to 380,000 micrograms/g Al. Rice grain contained about 3.4 times more F than that in the control area, but some kinds of agricultural products, egg plants (S. melongena L.), mulberry plants (M. japonica Bailey non Sieb.), and soy beans (G. max (L.) Merrill) were almost equal to that of controls. Also, the high F concentration in the hair and nails of some workers was affected by available F contents in the emission from the factory as well as food and water surrounding the aluminum factory compared with those of control area.

  14. Tilt and Translation Motion Perception during Pitch Tilt with Visual Surround Translation

    NASA Technical Reports Server (NTRS)

    O'Sullivan, Brita M.; Harm, Deborah L.; Reschke, Millard F.; Wood, Scott J.

    2006-01-01

    The central nervous system must resolve the ambiguity of inertial motion sensory cues in order to derive an accurate representation of spatial orientation. Previous studies suggest that multisensory integration is critical for discriminating linear accelerations arising from tilt and translation head motion. Visual input is especially important at low frequencies where canal input is declining. The NASA Tilt Translation Device (TTD) was designed to recreate postflight orientation disturbances by exposing subjects to matching tilt self motion with conflicting visual surround translation. Previous studies have demonstrated that brief exposures to pitch tilt with foreaft visual surround translation produced changes in compensatory vertical eye movement responses, postural equilibrium, and motion sickness symptoms. Adaptation appeared greatest with visual scene motion leading (versus lagging) the tilt motion, and the adaptation time constant appeared to be approximately 30 min. The purpose of this study was to compare motion perception when the visual surround translation was inphase versus outofphase with pitch tilt. The inphase stimulus presented visual surround motion one would experience if the linear acceleration was due to foreaft self translation within a stationary surround, while the outofphase stimulus had the visual scene motion leading the tilt by 90 deg as previously used. The tilt stimuli in these conditions were asymmetrical, ranging from an upright orientation to 10 deg pitch back. Another objective of the study was to compare motion perception with the inphase stimulus when the tilts were asymmetrical relative to upright (0 to 10 deg back) versus symmetrical (10 deg forward to 10 deg back). Twelve subjects (6M, 6F, 22-55 yrs) were tested during 3 sessions separated by at least one week. During each of the three sessions (out-of-phase asymmetrical, in-phase asymmetrical, inphase symmetrical), subjects were exposed to visual surround translation

  15. Real-time and low-cost embedded platform for car's surrounding vision system

    NASA Astrophysics Data System (ADS)

    Saponara, Sergio; Franchi, Emilio

    2016-04-01

    The design and the implementation of a flexible and low-cost embedded system for real-time car's surrounding vision is presented. The target of the proposed multi-camera vision system is to provide the driver a better view of the objects that surround the vehicle. Fish-eye lenses are used to achieve a larger Field of View (FOV) but, on the other hand, introduce radial distortion of the images projected on the sensors. Using low-cost cameras there could be also some alignment issues. Since these complications are noticeable and dangerous, a real-time algorithm for their correction is presented. Then another real-time algorithm, used for merging 4 camera video streams together in a single view, is described. Real-time image processing is achieved through a hardware-software platform

  16. A low-cost embedded platform for car's surrounding vision system

    NASA Astrophysics Data System (ADS)

    Saponara, S.; Fontanelli, G.; Fanucci, L.; Franchi, E.

    2014-05-01

    The design and the implementation of a flexible and low-cost embedded system for car's surrounding vision is presented. The target of the proposed multi-camera vision system is to provide the driver a better view of the objects that surround the vehicle during maneuvering. Fish-eye lenses are used to achieve a larger field of view (FOV) but, on the other hand, introduce radial distortion of the images projected on the sensors. Using low-cost cameras there could be also some alignment issues. Since these complications are noticeable and dangerous, a real-time algorithm for their correction and for the merging of 4 cameras video showed in a single view is presented.

  17. Literature assessment of the Charlotte Harbor estuarine system and surrounding area, Southwest Florida

    USGS Publications Warehouse

    Stoker, Yvonne E.; Karavitis, George A.

    1983-01-01

    The Governor of Florida established the Charlotte Harbor Resource Planning and Management committee to recommend the course of action Florida should take in planning for potential growth in the rapidly growing area surrounding Charlotte Harbor. In May 1981, the U.S. Geological Survey began a planning study to determine detailed hydrologic study needs of the Charlotte Harbor area. A literature search of available data and reports pertaining to the Charlotte Harbor estuarine system and surrounding area resulted in almost 1,300 references. This report contains all references collected during this search. Some of the major reference topics are altered freshwater flow, water quality of the harbor and drainage systems, circulation and tides, coastal and marine resources, fisheries, geology and hydrology of the area, impact studies, water resources, flora and fauna of the area, and water supply. Sixty-eight key words or subject identifiers are used to the index report. (USGS)

  18. A neutron diffraction study of local stress concentrations surrounding defects in pipeline steel

    NASA Astrophysics Data System (ADS)

    Clapham, L.; Sabet-Sharghi, R.; Holden, T.; Atherton, D. L.

    Magnetic flux leakage (MFL) is the most commonly used technique for the in-service inspection of both gas and oil pipelines. However, MFL is sensitive to the stress state of the pipe wall and the area surrounding defects. MFL tools are often calibrated using pipe sections with defects artificially introduced into the pipe wall prior to the pipe being pressurized. Naturally occurring defects, however, occur while the pipe wall is under stress due to line pressure. In this study, neutron diffraction is used to map the strain surrounding the two defects that have been introduced into plates of pipeline grade steel, one into a plate prior to uniaxial loading, the second into a plate held at a constant background load high enough to ensure that stress at the edge of the defect exceeds the elastic limit of the material.

  19. Calculation and experimental validation of spectral properties of microsize grains surrounded by nanoparticles.

    PubMed

    Yu, Haitong; Liu, Dong; Duan, Yuanyuan; Wang, Xiaodong

    2014-04-01

    Opacified aerogels are particulate thermal insulating materials in which micrometric opacifier mineral grains are surrounded by silica aerogel nanoparticles. A geometric model was developed to characterize the spectral properties of such microsize grains surrounded by much smaller particles. The model represents the material's microstructure with the spherical opacifier's spectral properties calculated using the multi-sphere T-matrix (MSTM) algorithm. The results are validated by comparing the measured reflectance of an opacified aerogel slab against the value predicted using the discrete ordinate method (DOM) based on calculated optical properties. The results suggest that the large particles embedded in the nanoparticle matrices show different scattering and absorption properties from the single scattering condition and that the MSTM and DOM algorithms are both useful for calculating the spectral and radiative properties of this particulate system. PMID:24718167

  20. Influence of interface stabilisers and surrounding aqueous phases on nematic liquid crystal shells.

    PubMed

    Noh, JungHyun; Reguengo De Sousa, Kevin; Lagerwall, Jan P F

    2016-01-14

    We investigate the nematic-isotropic (N-I) transition in shells of the liquid crystal 5CB, surrounded by aqueous phases that conventionally are considered to be immiscible with 5CB. The aqueous phases contain either sodium dodecyl sulfate (SDS) or polyvinyl alcohol (PVA) as stabiliser, the former additionally promoting homeotropic director alignment. For all shell configurations we find a depression of the clearing point compared to pure 5CB, indicating that a non-negligible fraction of the constituents of the surrounding phases enter the shell, predominantly water. In hybrid-aligned shells, with planar outer and homeotropic inner boundary (or vice versa), the N-I transition splits into two steps, with a consequent three-step textural transformation. We explain this as a result of the order-enhancing effect of a monolayer of radially aligned SDS molecules adsorbed at the homeotropic interface. PMID:26512764

  1. A summary of the controversy surrounding off-label medications in men's health.

    PubMed

    Parker, Adam; Bruha, Matthew; Akinola, Oluwaseun; Welliver, Charles

    2016-04-01

    While there are common and accepted practices in men's health, barriers exist to treatment of these disorders with Food and Drug Administration (FDA) approved medications. In male factor infertility, these barriers include studies that are often underpowered for desired outcomes. This has led to the use of medications previously examined in females in an off-label fashion for treatment of male infertility. Issues surrounding the treatment of hypogonadism in men are more complex, becoming increasingly so in the last few years. Drug companies have developed compounds for treatment of hypogonadism for particular subgroups of men. However, the indicated groups for these medications are narrow leading to these medications being regularly used for an indication the FDA considers to be part of "normal aging". This work will examine the controversy surrounding the use of off-label medications in men's health and how factors like pharma advertising, FDA regulation and difficulties in creating adequate studies has affected the current paradigm. PMID:27141447

  2. Seismological detection of low-velocity anomalies surrounding the mantle transition zone in Japan subduction zone

    NASA Astrophysics Data System (ADS)

    Liu, Zhen; Park, Jeffrey; Karato, Shun-ichiro

    2016-03-01

    In the Japan subduction zone, a locally depressed 660 discontinuity has been observed beneath northeast Asia, suggesting downwelling of materials from the mantle transition zone (MTZ). Vertical transport of water-rich MTZ materials across the major mineral phase changes could lead to water release and to partial melting in surrounding mantle regions, causing seismic low-velocity anomalies. Melt layers implied by low-velocity zones (LVZs) above the 410 discontinuity have been detected in many regions, but seismic evidence for partial melting below the 660 discontinuity has been limited. High-frequency migrated Ps receiver functions indicate LVZs below the depressed 660 discontinuity and above the 410 discontinuity in the deep Japan subduction zone, suggesting dehydration melting induced by water transport out of the MTZ. Our results provide insights into water circulation associated with dynamic interactions between the subducted slab and surrounding mantle.

  3. Edge analyzing properties of center/surround response functions in cybernetic vision

    NASA Technical Reports Server (NTRS)

    Jobson, D. J.

    1984-01-01

    The ability of center/surround response functions to make explicit high resolution spatial information in optical images was investigated by performing convolutions of two dimensional response functions and image intensity functions (mainly edges). The center/surround function was found to have the unique property of separating edge contrast from shape variations and of providing a direct basis for determining contrast and subsequently shape of edges in images. Computationally simple measures of contrast and shape were constructed for potential use in cybernetic vision systems. For one class of response functions these measures were found to be reasonably resilient for a range of scan direction and displacements of the response functions relative to shaped edges. A pathological range of scan directions was also defined and methods for detecting and handling these cases were developed. The relationship of these results to biological vision is discussed speculatively.

  4. Assessment of land degradation and its spatial and temporal variation in Beijing surrounding area

    NASA Astrophysics Data System (ADS)

    Li, Shuang; Dong, Suocheng; Zhang, Xiaojun; Zhiqiang, Gao

    2005-08-01

    The indulgence in willful persecution of sandstorm had made great attention of many countries around the world. Chinese government and the Chinese academy of science going with some other countries have devoted a large amount of vigor to study the crucial environment problem. Due to the main source areas of sandstorm all located in the arid and semi-arid regions where there have great area, hard natural condition and bad traffic condition, it's very difficult to accomplish source area and the reason of sandstorm. For this destination, a international cooperation organization has been established to clarify the occur mechanism, transfer process and the following environment impact of sandstorm. The organization includes many researchers come form USA, Japan, Korea, and so on. Beijing surrounding area is one of the main sandstorm sources in recent years. In order to understand fully of the sandstorm form and development, we analyzed the land use degradation of Beijing surrounding area during the last ten years. 71 scenes Landsat TM/ETM, 611 scenes DRG and DEM data had been processed in our study. This paper made a detail describe of using Landsat image data and high resolution DEM data to construe the soil erosion and vegetation degenerate. The result shows that the irrational human activities and land use style are the main factors of land use degradation. In case of Beijing surrounding area, the land degradation directly impacted the frequency and intensity of sand & dust storm in Northern China. The case study region of Beijing surrounding area includes 51 counties that belong to three provinces and autonomous regions.

  5. Summertime ozone formation in Xi'an and surrounding areas, China

    NASA Astrophysics Data System (ADS)

    Feng, Tian; Bei, Naifang; Huang, Ru-Jin; Cao, Junji; Zhang, Qiang; Zhou, Weijian; Tie, Xuexi; Liu, Suixin; Zhang, Ting; Su, Xiaoli; Lei, Wenfang; Molina, Luisa T.; Li, Guohui

    2016-04-01

    In this study, the ozone (O3) formation in China's northwest city of Xi'an and surrounding areas is investigated using the Weather Research and Forecasting atmospheric chemistry (WRF-Chem) model during the period from 22 to 24 August 2013, corresponding to a heavy air pollution episode with high concentrations of O3 and PM2.5. The model generally performs well compared to measurements in simulating the surface temperature, relative humidity, and wind speed and direction, near-surface O3 and PM2.5 mass concentrations, and aerosol constituents. High aerosol concentrations in Xi'an and surrounding areas significantly decrease the photolysis frequencies and can reduce O3 concentrations by more than 50 µg m-3 (around 25 ppb) on average. Sensitivity studies show that the O3 production regime in Xi'an and surrounding areas is complicated, varying from NOx to VOC (volatile organic compound)-sensitive chemistry. The industrial emissions contribute the most to the O3 concentrations compared to biogenic and other anthropogenic sources, but neither individual anthropogenic emission nor biogenic emission plays a dominant role in the O3 formation. Under high O3 and PM2.5 concentrations, a 50 % reduction in all the anthropogenic emissions only decreases near-surface O3 concentrations by about 14 % during daytime. The complicated O3 production regime and high aerosol levels pose a challenge for O3 control strategies in Xi'an and surrounding areas. Further investigation regarding O3 control strategies will need to be performed, taking into consideration the rapid changes in anthropogenic emissions that are not reflected in the current emission inventories and the uncertainties in the meteorological field simulations.

  6. An aerial radiological survey of the area surrounding the Maybell mill site, Maybell, Colorado

    SciTech Connect

    Jobst, J.E.

    1982-06-01

    An aerial radiological measuring system was used to survey the area surrounding Maybell, Colorado and the nearby mines and mill in late October and early November 1981. The survey was conducted for the US Department of Energy's Office of Operational Safety by the Department's Remote Sensing Laboratory, located in Las Vegas, Nevada. The highest measured radiation exposure rates (normalized to 3 feet above the ground) exceed 300 microroentgens per hour ({mu}R/h) over the leach piles at the mill.

  7. Cerebellar brain inhibition in the target and surround muscles during voluntary tonic activation.

    PubMed

    Panyakaew, Pattamon; Cho, Hyun Joo; Srivanitchapoom, Prachaya; Popa, Traian; Wu, Tianxia; Hallett, Mark

    2016-04-01

    Motor surround inhibition is the neural mechanism that selectively favours the contraction of target muscles and inhibits nearby muscles to prevent unwanted movements. This inhibition was previously reported at the onset of a movement, but not during a tonic contraction. Cerebellar brain inhibition (CBI) is reduced in active muscles during tonic activation; however, it has not been studied in the surround muscles. CBI was evaluated in the first dorsal interosseus (FDI) muscle as the target muscle, and the abductor digiti minimi, flexor carpi radialis and extensor carpi radialis muscles as surround muscles, during rest and tonic activation of the FDI muscle in 21 subjects. Cerebellar stimulation was performed under magnetic resonance imaging-guided neuronavigation targeting lobule VIII of the cerebellar hemisphere. Stimulus intensities for cerebellar stimulation were based on the resting motor cortex threshold (RMT) and adjusted for the depth difference between the cerebellar and motor cortices. We used 90-120% of the adjusted RMT as the conditioning stimulus intensity during rest. The intensity that generated the best CBI at rest in the FDI muscle was selected for use during tonic activation. During selective tonic activation of the FDI muscle, CBI was significantly reduced only for the FDI muscle, and not for the surround muscles. Unconditioned motor evoked potential sizes were increased in all muscles during FDI muscle tonic activation as compared with rest, despite background electromyography activity increasing only for the FDI muscle. Our study suggests that the cerebellum may play an important role in selective tonic finger movement by reducing its inhibition in the motor cortex only for the relevant agonist muscle. PMID:26900871

  8. Variability of Atmospheric CO2 Over India and Surrounding Oceans and Control by Surface Fluxes

    NASA Astrophysics Data System (ADS)

    Nayak, R. K.; Dadhwal, V. K.; Majumdar, A.; Patel, N. R.; Dutt, C. B. S.

    2011-08-01

    In the present study, seasonal and inter-annual variability of atmospheric CO2 concentration over India and surrounding oceans during 2002-2010 derived from Atmospheric InfrarRed Sounder observation and their relation with the natural flux exchanges over terrestrial Indian and surrounding oceans were analyzed. The natural fluxes over the terrestrial Indian in the form of net primary productivity (NPP) were simulated based on a terrestrial biosphere model governed by time varying climate parameters (solar radiation, air temperature, precipitation etc) and satellite greenness index together with the land use land cover and soil attribute maps. The flux exchanges over the oceans around India (Tropical Indian Ocean: TIO) were calculated based on a empirical model of CO2 gas dissolution in the oceanic water governed by time varying upper ocean parameters such as gradient of partial pressure of CO2 between ocean and atmosphere, winds, sea surface temperature and salinity. Comparison between the variability of atmospheric CO2 anomaly with the anomaly of surface fluxes over India and surrounding oceans suggests that biosphere uptake over India and oceanic uptake over the south Indian Ocean could play positive role on the control of seasonal variability of atmospheric carbon dioxide growth rate. On inter-annual scale, flux exchanges over the tropical north Indian Ocean could play positive role on the control of atmospheric carbon dioxide growth rate.

  9. Geometric-model-based segmentation of the prostate and surrounding structures for image-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Tang, Xiaoli; Jeong, Yongwon; Radke, Richard J.; Chen, George T. Y.

    2004-01-01

    We present a computer vision tool to improve the clinical outcome of patients undergoing radiation therapy for prostate cancer by improving irradiation technique. While intensity modulated radiotherapy (IMRT) allows one to irradiate a specific region in the body with high accuracy, it is still difficult to know exactly where to aim the radiation beam on every day of the 30~40 treatments that are necessary. This paper presents a geometric model-based technique to accurately segment the prostate and other surrounding structures in a daily serial CT image, compensating for daily motion and shape variation. We first acquire a collection of serial CT scans of patients undergoing external beam radiotherapy, and manual segmentation of the prostate and other nearby structures by radiation oncologists. Then we train shape and local appearance models for the structures of interest. When new images are available, an iterative algorithm is applied to locate the prostate and surrounding structures automatically. Our experimental results show that excellent matches can be given to the prostate and surrounding structure. Convergence is declared after 10 iterations. For 256 x 256 images, the mean distance between the hand-segmented contour and the automatically estimated contour is about 1.5 pixels (2.44 mm), with variance about 0.6 pixel (1.24 mm).

  10. Influence of a polarizable surrounding on the electronically excited states of aggregated perylene materials.

    PubMed

    Bellinger, Daniel; Settels, Volker; Liu, Wenlan; Fink, Reinhold F; Engels, Bernd

    2016-06-30

    To tune the efficiency of organic semiconductor devices it is important to understand limiting factors as trapping mechanisms for excitons or charges. An understanding of such mechanisms deserves an accurate description of the involved electronical states in the given environment. In this study, we investigate how a polarizable surrounding influences the relative positions of electronically excited states of dimers of different perylene dyes. Polarization effects are particularly interesting for these systems, because gas phase computations predict that the CT states lie slightly above the corresponding Frenkel states. A polarizable environment may change this energy order because CT states are thought to be more sensitive to a polarizable surrounding than Frenkel states. A first insight we got via a TD-HF approach in combination with a polarizable continuum model (PCM). These give limited insights because TD-HF overestimates excitation energies of CT states. However, SCS-CC2 approaches, which are sufficiently accurate, cannot easily be used in combination with continuum solvent models. Hence, we developed two approaches to combine gas phase SCS-CC2 results with solvent effects based on TD-HF computations. Their accuracies were finally checked via ADC(2)//COSMO computations. The results show that for perylene dyes a polarizable surrounding alone does not influence the energetic ordering of CT and Frenkel states. Variations in the energy order of the states only result from nuclear relaxation effects after the excitation process. © 2016 Wiley Periodicals, Inc. PMID:27030658

  11. Density of insect-pollinated grassland plants decreases with increasing surrounding land-use intensity.

    PubMed

    Clough, Yann; Ekroos, Johan; Báldi, András; Batáry, Péter; Bommarco, Riccardo; Gross, Nicolas; Holzschuh, Andrea; Hopfenmüller, Sebastian; Knop, Eva; Kuussaari, Mikko; Lindborg, Regina; Marini, Lorenzo; Öckinger, Erik; Potts, Simon G; Pöyry, Juha; Roberts, Stuart Pm; Steffan-Dewenter, Ingolf; Smith, Henrik G

    2014-09-01

    Pollinator declines have raised concerns about the persistence of plant species that depend on insect pollination, in particular by bees, for their reproduction. The impact of pollinator declines remains unknown for species-rich plant communities found in temperate seminatural grasslands. We investigated effects of land-use intensity in the surrounding landscape on the distribution of plant traits related to insect pollination in 239 European seminatural grasslands. Increasing arable land use in the surrounding landscape consistently reduced the density of plants depending on bee and insect pollination. Similarly, the relative abundance of bee-pollination-dependent plants increased with higher proportions of non-arable agricultural land (e.g. permanent grassland). This was paralleled by an overall increase in bee abundance and diversity. By isolating the impact of the surrounding landscape from effects of local habitat quality, we show for the first time that grassland plants dependent on insect pollination are particularly susceptible to increasing land-use intensity in the landscape. PMID:25040328

  12. Effect of immediate loading on the biomechanical properties of bone surrounding the miniscrew implants.

    PubMed

    Iijima, Masahiro; Nakagaki, Susumu; Yasuda, Yoshitaka; Handa, Keisuke; Koike, Toshiyuki; Muguruma, Takeshi; Saito, Takashi; Mizoguchi, Itaru

    2013-10-01

    The aim of this study was to investigate the effect of immediate loading on the biomechanical properties of bone surrounding a miniscrew implant. Forty titanium alloy miniscrew implants were placed on the buccal side of the maxillae and mandibles in four beagle dogs. Twelve pairs of miniscrew implants were immediately loaded with approximately 150 g of continuous force using nickel-titanium coil springs and the remaining 16 implants were left unloaded for 8 weeks. Nanoindentation testing was performed (peak load 10 mN) and the hardness and elastic modulus were calculated. Two series of indentations (in cortical and trabecular bone) for both the compression and tension sides were made. For each site, five indentations were placed approximately 25 μm from the implant-bone interface and 250 μm from the screw thread. The mean hardness and elastic modulus were generally higher in mandibles than maxillae and were higher in cortical bone than in trabecular bone. The trabecular bone near the implant-bone interface on the compression side was significantly harder than that at other locations in trabecular bone. In conclusion, this is the first study that has investigated the biomechanical properties of bone surrounding a miniscrew implant under immediate loading using nanoindentation testing. The mechanical properties of bone surrounding a miniscrew implant may be influenced by immediate loading. PMID:22952154

  13. System for detecting interfaces between mineral seams and the surrounding earth formations

    SciTech Connect

    Ingle, J.E.; Moon, J.L.

    1981-04-21

    The present invention contemplates a system for detecting an interface between a mineral seam and the surrounding earth formation utilizing a radiation source and a radiation receiver mounted on a miner having a positionable cutter assembly. As the miner is moved into the coal seam, a first distance is continuously sensed between one surface formed in the mineral seam by the miner cutter assembly and the surrounding earth formation and the miner cutter assembly is positioned in response to the sensed first distance. As the miner is withdrawn from the coal seam, a second distance is continuously sensed between one surface formed in the mineral seam by the miner cutter assembly and the surrounding earth formation and the miner cutter assembly is positioned in response to the sensed second distance. A substantial portion of the space between the wall formed in the mineral seam by the miner cutter assembly and the radiation source and radiation receiver is substantially filled with a material having a density greater than the density of air to direct a substantial portion of the radiation through the mineral seam.

  14. River restoration success depends on the species pool of the immediate surroundings.

    PubMed

    Sundermann, Andrea; Stoll, Stefan; Haase, Peter

    2011-09-01

    Previous studies evaluating the success of river restorations have rarely found any consistent effects on benthic invertebrate assemblages. In this study, we analyzed data from 24 river restoration projects in Germany dating back 1 to 12 years and 1231 data sets from adjacent river reaches that lie within 0-5, 5-10, and 10-15 km rings centered on the restored sites. We calculated restoration success and recolonization potential of adjacent river reaches based on stream-type-specific subsets of taxa indicative for good or bad habitat quality. On average, the restorations did not improve the benthic invertebrate community quality. However, we show that restoration success depends on the presence of source populations of desired taxa in the surrounding of restored sites. Only where source populations of additional desired taxa existed within a 0-5 km ring around the restored sites were benthic invertebrate assemblages improved by the restoration. Beyond the 5-km rings, this recolonization effect was no longer detected. We present here the first field results to support the debated argument that a lack of source populations in the areas surrounding restored sites may play an important role in the failure to establish desired invertebrate communities by the means of river restorations. In contrast, long-range dispersal of invertebrates seems to play a subordinate role in the recolonization of restored sites. However, because the surroundings of the restored sites were far from good ecological quality, the potential for improvement of restored sites was limited. PMID:21939037

  15. Landscape surrounding human settlements and Anopheles albimanus (Diptera: Culicidae) abundance in Southern Chiapas, Mexico.

    PubMed

    Rodriguez, A D; Rodriguez, M H; Hernandez, J E; Dister, S W; Beck, L R; Rejmankova, E; Roberts, D R

    1996-01-01

    Landscape characteristics that may influence important components of the Anopheles albimanus Wiedemann life cycle, including potential breeding sites, suitable diurnal resting sites, and possible sources of blood meals, were analyzed at 14 villages in a malarious area of southern Mexico. An. albimanus adults were collected weekly in each village using UV-light traps between July 1991 and August 1992. Based on rainfall, the study was divided into 6 seasonal periods. Villages were considered to have high mosquito abundance when >5 mosquitoes per trap per night were collected during any 1 of the 6 seasonal periods. The extension and frequency of 11 land cover types surrounding villages were determined using aerial photographs and subsequently verified through field surveys. Elevation was the main landscape feature that separated villages with low and high mosquito abundance. All villages with high mosquito abundance were below 25 m. Transitional and mangrove land cover types were found only in the high mosquito abundance group. Flooded areas as potential breeding sites and potential adult resting sites in unmanaged pastures were significantly more frequent in areas surrounding villages with high mosquito abundance. No significant differences in density of cattle and horses were found among village groups. Overall, surrounding breeding sites located at low elevations in flooded unmanaged pastures seemed to be the most important determinants of An. albimanus adult abundance in the villages. PMID:8906903

  16. Effects of surrounding land use on metal accumulation in environments and submerged plants in subtropical ponds.

    PubMed

    Liu, Hui; Bu, Hongmei; Liu, Guihua; Wang, Zhixiu; Liu, Wenzhi

    2015-12-01

    Ponds are widely used as stormwater treatment facilities to retain contaminants, including metals, and to improve water quality throughout the world. However, there is still a limited understanding of the effects of surrounding land use on metal accumulation in pond environments and organisms. To address this gap, we measured the concentrations of nine metals (i.e., Al, Ba, Ca, K, Li, Mg, Na, Se, and Sr) in water, sediments, and submerged plants collected from 37 ponds with different surrounding land uses in southwestern China and assessed the metal accumulation capacity of four dominant submerged plant species. Our results showed that Al, Ca, and K concentrations in the water were above drinking water standards. In the sediments, the average concentrations of Ca and Sr were higher than the corresponding soil background values. Ceratophyllum demersum L. could accumulate more K in aboveground biomass than Myriophyllum spicatum L. and Potamogeton maackianus A. Benn. The K concentration in submerged plants was positively influenced by the corresponding metal concentration in the water and negatively influenced by water temperature. Among the nine studied metals, only the water K concentration in ponds receiving agricultural runoff was significantly higher than that for ponds receiving urban and forested runoff. This result suggests that surrounding land use types have no significant effect on metal accumulation in sediments and submerged plants in the studied ponds. A large percentage of the metals in these ponds may be derived from natural sources such as the weathering of rocks. PMID:26199006

  17. Assessing protected area effectiveness using surrounding (buffer) areas environmentally similar to the target area.

    PubMed

    Mas, Jean-François

    2005-06-01

    Many studies are based on the assumption that an area and its surrounding (buffer) area present similar environmental conditions and can be compared. For example, in order to assess the effectiveness of a protected area, the land use/cover changes are compared inside the park with its surroundings. However, the heterogeneity in spatial variables can bias this assessment: we have shown that most of the protected areas in Mexico present significant environmental differences between their interior and their surroundings. Therefore, a comparison that aims at assessing the effectiveness of conservation strategies, must be cautioned. In this paper, a simple method which allows the generation of a buffer area that presents similar conditions with respect to a set of environmental variables is presented. The method was used in order to assess the effectiveness of the Calakmul Biosphere Reserve, a protected area located in the south-eastern part of Mexico. The annual rate of deforestation inside the protected area, the standard buffer area (based upon distance from the protected area only) and the similar buffer area (taking into account distance along with some environmental variables) were 0.3, 1.3 and 0.6%, respectively. These results showed that the protected area was effective in preventing land clearing, but that the comparison with the standard buffer area gave an over-optimistic vision of its effectiveness. PMID:15952512

  18. Element distribution is altered in a zone surrounding human glioblastoma multiforme.

    PubMed

    Dehnhardt, Markus; Zoriy, Myroslav V; Khan, Zahidul; Reifenberger, Guido; Ekström, Tomas J; Sabine Becker, J; Zilles, Karl; Bauer, Andreas

    2008-01-01

    Recent data indicate that A(1) adenosine receptor (A(1)AR) density is increased in a zone surrounding human and experimental gliomas. On the contrary, tumor tissue and adjacent brain tissue show low to intermediate A(1)AR densities. In order to assess whether changes in A(1)AR expression are indicating further processes of a chemical reorganization of the peritumoral zone, we investigated element concentrations and distribution patterns of copper and zinc in six human glioblastoma multiforme (GBM) specimens by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Uranium and lead were used as external standards. Copper and zinc levels were increased in a peritumoral zone corresponding to the region of elevated A(1)AR density. They showed a lower density in the solid tumor in comparison to surrounding brain tissue, although the cellular density was higher within GBM. Our findings suggest that the immediate vicinity of GBM is characterized by increased levels of copper and zinc supporting the view that higher A(1)AR density surrounding GBM is not an isolated alteration of peritumoral tissue but an indicator of complex changes in the vicinity of infiltrative tumors. Further research is needed to explore the pathophysiological consequences of altered peritumoral element distribution. PMID:18319136

  19. Design and Implementation of Surrounding Transaction Plotting and Management System Based on Google Map API

    NASA Astrophysics Data System (ADS)

    Cao, Y. B.; Hua, Y. X.; Zhao, J. X.; Guo, S. M.

    2013-11-01

    With China's rapid economic development and comprehensive national strength growing, Border work has become a long-term and important task in China's diplomatic work. How to implement rapid plotting, real-time sharing and mapping surrounding affairs has taken great significance for government policy makers and diplomatic staff. However, at present the already exists Boundary information system are mainly have problems of Geospatial data update is heavily workload, plotting tools are in a state of serious lack of, Geographic events are difficult to share, this phenomenon has seriously hampered the smooth development of the border task. The development and progress of Geographic information system technology especially the development of Web GIS offers the possibility to solve the above problems, this paper adopts four layers of B/S architecture, with the support of Google maps service, uses the free API which is offered by Google maps and its features of openness, ease of use, sharing characteristics, highresolution images to design and implement the surrounding transaction plotting and management system based on the web development technology of ASP.NET, C#, Ajax. The system can provide decision support for government policy makers as well as diplomatic staff's real-time plotting and sharing of surrounding information. The practice has proved that the system has good usability and strong real-time.

  20. Impacts of Sewer Leaks on Surrounding Groundwater and Surface Water Quality in Singapore

    NASA Astrophysics Data System (ADS)

    Ly, D.; Chui, T. M.

    2011-12-01

    Underground sewers deteriorate over time resulting in cracks and joint defects. Sewage thus leaks out of the sewers and contaminates the surrounding groundwater. Singapore does not directly use groundwater as a water supply. However, contaminated groundwater flows into the drains nearby through weep holes, and subsequently enters water supply reservoirs. This study examines the impacts of sewage leaks on surrounding groundwater and surface water quality by modeling the interactions between leaky sewers, groundwater and drains. It first explores the representations of important yet challenging boundary conditions, namely weep holes and leaky sewers, so that their fluxes vary realistically with water pressure throughout a simulation. It then simulates groundwater flow and contaminant transport from leaky sewers to nearby drains over a period of ten years. It further rehabilitates the sewers and models the attenuation of contamination plume for another ten years. The results of this project contribute to the modeling and understanding of the potential impacts of sewer leaks on surrounding groundwater and surface water quality. For example, groundwater quality changes with hydrologic conditions, and it is highest during heavy rainfall and times of high water table because of the low leakage and high dilution rates. Water quality fluctuates daily or even hourly in the vicinity of the sewers, but is more stable in the flow through the weep holes into the drains. Overall, this study benefits the sewer leak monitoring and sewer rehabilitation in many urban areas worldwide.