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Sample records for operational magnitudes implantation

  1. Low-magnitude high-frequency loading, by whole-body vibration, accelerates early implant osseointegration in ovariectomized rats

    PubMed Central

    LIANG, YONG-QIANG; QI, MENG-CHUN; XU, JIANG; XU, JUAN; LIU, HUA-WEI; DONG, WEI; LI, JIN-YUAN; HU, MIN

    2014-01-01

    Osteoporosis deteriorates jaw bone quality and may compromise early implant osseointegration and early implant loading. The influence of low-magnitude, high-frequency (LMHF) vibration on peri-implant bone healing and implant integration in osteoporotic bones remains poorly understood. LMHF loading via whole-body vibration (WBV) for 8 weeks has previously been demonstrated to significantly enhance bone-to-implant contact, peri-implant bone fraction and implant mechanical properties in osteoporotic rats. In the present study, LMHF loading by WBV was performed in osteoporotic rats, with a loading duration of 4 weeks during the early stages of bone healing. The results indicated that 4-week LMHF loading by WBV partly reversed the negative effects of osteoporosis and accelerated early peri-implant osseointegration in ovariectomized rats. PMID:25270245

  2. Pre-operative drilling simulation method for dental implant treatment.

    PubMed

    Arataki, Tomohiko; Furuya, Yoshitaka; Ito, Taichi; Miyashita, Yuko; Shimamura, Ichiro; Yajima, Yasutomo

    2007-02-01

    The position, depth and direction of implant placement are often planned based on evaluation of radiographs and study casts. Insertion planned in such a manner may not be adequate for precise and safe surgery in some cases due to inadequate working clearance in the oral cavity. In order to obtain high initial stability and ensure osseointegration at the implant-bone interface, careful and precise drilling must be performed at the implant placement site. Therefore, we propose the necessity of evaluating the operability of implant treatment-devices prior to surgery. The amount of handling space needed during implant placement surgery was determined. The results showed that for implants with a length of 7-18 mm, a vertical distance of as much as 50-60 mm was required, depending on the implant platform. These results suggest the necessity of pre-operative drilling simulation in each individual. Handling space was measured with angled heads and probes fabricated on a trial basis for pre-surgical drilling simulation in the oral cavity. We believe that these instruments may be clinically useful in estimating the amount of handling space required prior to surgery and ensuring precise implant placement. Evaluation of the intra-oral environment for handling of treatment devices should be included in the pre-surgical intra-oral evaluation of dental implant cases to avoid changes in treatment planning due to intra-oral interference during the course of surgery. PMID:17721064

  3. A touch probe method of operating an implantable RFID tag for orthopedic implant identification.

    PubMed

    Liu, Xiaoyu; Berger, J Lee; Ogirala, Ajay; Mickle, Marlin H

    2013-06-01

    The major problem in operating an implantable radio-frequency identification (RFID) tag embedded on an orthopedic implant is low efficiency because of metallic interference. To improve the efficiency, this paper proposes a method of operating an implantable passive RFID tag using a touch probe at 13.56 MHz. This technology relies on the electric field interaction between two pairs of electrodes, one being a part of the touch probe placed on the surface of tissue and the other being a part of the tag installed under the tissue. Compared with using a conventional RFID antenna such as a loop antenna, this method has a better performance in the near field operation range to reduce interference with the orthopedic implant. Properly matching the touch probe and the tag to the tissue and the implant reduces signal attenuation and increases the overall system efficiency. The experiments have shown that this method has a great performance in the near field transcutaneous operation and can be used for orthopedic implant identification. PMID:23853323

  4. Industrial hygiene and control technology assessment of ion implantation operations.

    PubMed

    Ungers, L J; Jones, J H

    1986-10-01

    Ion implantation is a process used to create the functional units (pn junctions) of integrated circuits, photovoltaic (solar) cells and other semiconductor devices. During the process, ions of an impurity or a "dopant" material are created, accelerated and imbedded in wafers of silicon. Workers responsible for implantation equipment are believed to be at risk from exposure to both chemical (dopant compounds) and physical (ionizing radiation) agents. In an effort to characterize the chemical exposures, monitoring for chemical hazards was conducted near eleven ion implanters at three integrated circuit facilities, while ionizing radiation was monitored near four of these units at two of the facilities. The workplace monitoring suggests that ion implantation operators routinely are exposed to low-level concentrations of dopants. Although the exact nature of dopant compounds released to the work environment was not determined, area and personal samples taken during normal operating activities found concentrations of arsenic, boron and phosphorous below OSHA Permissible Exposure Limits (PELs) for related compounds; area samples collected during implanter maintenance activities suggest that a potential exists for more serious exposures. The results of badge dosimetry monitoring for ionizing radiation indicate that serious exposures are unlikely to occur while engineering controls remain intact. All emissions were detected at levels unlikely to result in exposures above the OSHA standard for the whole body (1.25 rems per calendar quarter). The success of existing controls in preventing worker exposures is discussed. Particular emphasis is given to the differential exposures likely to be experienced by operators and maintenance personnel.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3776837

  5. Multiple determinants of the effects of reinforcement magnitude on free-operant response rates

    PubMed Central

    Reed, Phil

    1991-01-01

    Four experiments examined the effects of increasing the number of food pellets given to hungry rats for a lever-press response. On a simple variable-interval 60-s schedule, increased number of pellets depressed response rates (Experiment 1). In Experiment 2, the decrease in response rate as a function of increased reinforcement magnitude was demonstrated on a variable-interval 30-s schedule, but enhanced rates of response were obtained with the same increase in reinforcement magnitude on a variable-ratio 30 schedule. In Experiment 3, higher rates of responding were maintained by the component of a concurrent variable-interval 60-s variable-interval 60-s schedule associated with a higher reinforcement magnitude. In Experiment 4, higher rates of response were produced in the component of a multiple variable-interval 60-s variable-interval 60-s schedule associated with the higher reinforcement magnitude. It is suggested that on simple schedules greater reinforcer magnitudes shape the reinforced pattern of responding more effectively than do smaller reinforcement magnitudes. This effect is, however, overridden by another process, such a contrast, when two magnitudes are presented within a single session on two-component schedules. PMID:16812628

  6. Pre- and post-operative management of dental implant placement. Part 1: management of post-operative pain.

    PubMed

    Bryce, G; Bomfim, D I; Bassi, G S

    2014-08-01

    Although dental implant placements have high success rates and a low incidence of morbidity, post-operative pain and complications with the healing process have been reported. There is little guidance available regarding optimal pre- and post-operative management of dental implant placement. This first paper discusses the mechanisms of pain associated with dental implant placement and offers guidance to clinicians on optimal pre- and post-operative pain management regimes. The second paper aims to discuss pre- and post-operative means of reducing the risk of early healing complications. PMID:25104691

  7. The Modulation of Operant Variation by the Probability, Magnitude, and Delay of Reinforcement

    ERIC Educational Resources Information Center

    Stahlman, W. David; Blaisdell, Aaron P.

    2011-01-01

    Recent studies have demonstrated that the expectation of reward delivery has an inverse relationship with operant behavioral variation (e.g., Stahlman, Roberts, & Blaisdell, 2010). Research thus far has largely focused on one aspect of reinforcement--the likelihood of food delivery. In two experiments with pigeons, we examined the effect of two…

  8. Optimal operating frequency in wireless power transmission for implantable devices.

    PubMed

    Poon, Ada S Y; O'Driscoll, Stephen; Meng, Teresa H

    2007-01-01

    This paper examines short-range wireless powering for implantable devices and shows that existing analysis techniques are not adequate to conclude the characteristics of power transfer efficiency over a wide frequency range. It shows, theoretically and experimentally, that the optimal frequency for power transmission in biological media can be in the GHz-range while existing solutions exclusively focus on the MHz-range. This implies that the size of the receive coil can be reduced by 10(4) times which enables the realization of fully integrated implantable devices. PMID:18003300

  9. Order of magnitude enhancement in neutron emission with deuterium-krypton admixture operation in miniature plasma focus device

    SciTech Connect

    Verma, Rishi; Lee, P.; Lee, S.; Springham, S. V.; Tan, T. L.; Rawat, R. S.; Krishnan, M.

    2008-09-08

    The effect of varied concentrations of deuterium-krypton (D{sub 2}-Kr) admixture on the neutron emission of a fast miniature plasma focus device was investigated. It was found that a judicious concentration of Kr in D{sub 2} can significantly enhance the neutron yield. The maximum average neutron yield of (1{+-}0.27)x10{sup 4} n/shot for pure D{sub 2} filling at 3 mbars was enhanced to (3.14{+-}0.4)x10{sup 5} n/shot with D{sub 2}+2% Kr admixture operation, which represents a >30-fold increase. More than an order of magnitude enhancement in the average neutron yield was observed over the broader operating range of 1-4 mbars for D{sub 2}+2% Kr and D{sub 2}+5% Kr admixtures.

  10. Pre-, Intra- and Post-Operative Imaging of Cochlear Implants.

    PubMed

    Vogl, T J; Tawfik, A; Emam, A; Naguib, N N N; Nour-Eldin, A; Burck, I; Stöver, T

    2015-11-01

    The purpose of this review is to present essential imaging aspects in patients who are candidates for a possible cochlear implant as well as in postsurgical follow-up. Imaging plays a major role in providing information on preinterventional topography, variations and possible infections. Preoperative imaging using DVT, CT, MRI or CT and MRI together is essential for candidate selection, planning of surgical approach and exclusion of contraindications like the complete absence of the cochlea or cochlear nerve, or infection. Relative contraindications are variations of the cochlea and vestibulum. Intraoperative imaging can be performed by fluoroscopy, mobile radiography or DVT. Postoperative imaging is regularly performed by conventional X-ray, DVT, or CT. In summary, radiological imaging has its essential role in the pre- and post-interventional period for patients who are candidates for cochlear implants. PMID:26327670

  11. Design and operation of a fully implantable SMA actuated implant for correcting short bowel syndrome

    NASA Astrophysics Data System (ADS)

    Utter, Brent; Luntz, Jonathan; Brei, Diann; Teitelbaum, Daniel; Okawada, Manabu; Miyasaka, Eiichi

    2009-03-01

    Short Bowel Syndrome (SBS) is medical condition characterized by insufficient small intestine length, leading to improper nutrient absorption and significant mortality rates. The complications of current treatment methods have encouraged the development of a novel treatment method based on mechanotransduction, the process through which mechanical tensile loading induces longitudinal growth of intestine. Animal based studies with simple extension devices have demonstrated the potential of the treatment to grow healthy bowel, but an implantable device suitable for clinical use remains undeveloped. This paper presents the development of an instrumented fully implantable bowel extender based upon a shape memory alloy driven linear ratchet that can be controlled and monitored remotely. The overall bowel extender system is described with respect to specifications for pig experimental tests. The functionality of the mechanical and electrical subsystems of the device are detailed and experimentally validated on the bench top, in segments of living bowel tissue removed from a pig, and in cadaveric pigs. Mechanical loading characteristics and safe load limits on bowel tissue are identified. Results from these experiments establish the readiness of the device to be tested in living pigs, enabling studies to move one step closer to clinical studies.

  12. Influence of ion source configuration and its operation parameters on the target sputtering and implantation process.

    PubMed

    Shalnov, K V; Kukhta, V R; Uemura, K; Ito, Y

    2012-06-01

    In the work, investigation of the features and operation regimes of sputter enhanced ion-plasma source are presented. The source is based on the target sputtering with the dense plasma formed in the crossed electric and magnetic fields. It allows operation with noble or reactive gases at low pressure discharge regimes, and, the resulting ion beam is the mixture of ions from the working gas and sputtering target. Any conductive material, such as metals, alloys, or compounds, can be used as the sputtering target. Effectiveness of target sputtering process with the plasma was investigated dependently on the gun geometry, plasma parameters, and the target bias voltage. With the applied accelerating voltage from 0 to 20 kV, the source can be operated in regimes of thin film deposition, ion-beam mixing, and ion implantation. Multi-component ion beam implantation was applied to α-Fe, which leads to the surface hardness increasing from 2 GPa in the initial condition up to 3.5 GPa in case of combined N(2)-C implantation. Projected range of the implanted elements is up to 20 nm with the implantation energy 20 keV that was obtained with XPS depth profiling. PMID:22755619

  13. Influence of ion source configuration and its operation parameters on the target sputtering and implantation process

    SciTech Connect

    Shalnov, K. V.; Kukhta, V. R.; Uemura, K.; Ito, Y.

    2012-06-15

    In the work, investigation of the features and operation regimes of sputter enhanced ion-plasma source are presented. The source is based on the target sputtering with the dense plasma formed in the crossed electric and magnetic fields. It allows operation with noble or reactive gases at low pressure discharge regimes, and, the resulting ion beam is the mixture of ions from the working gas and sputtering target. Any conductive material, such as metals, alloys, or compounds, can be used as the sputtering target. Effectiveness of target sputtering process with the plasma was investigated dependently on the gun geometry, plasma parameters, and the target bias voltage. With the applied accelerating voltage from 0 to 20 kV, the source can be operated in regimes of thin film deposition, ion-beam mixing, and ion implantation. Multi-component ion beam implantation was applied to {alpha}-Fe, which leads to the surface hardness increasing from 2 GPa in the initial condition up to 3.5 GPa in case of combined N{sub 2}-C implantation. Projected range of the implanted elements is up to 20 nm with the implantation energy 20 keV that was obtained with XPS depth profiling.

  14. Tungsten contamination in ion implantation

    NASA Astrophysics Data System (ADS)

    Polignano, M. L.; Barbarossa, F.; Galbiati, A.; Magni, D.; Mica, I.

    2016-06-01

    In this paper the tungsten contamination in ion implantation processes is studied by DLTS analysis both in typical operating conditions and after contamination of the implanter by implantation of wafers with an exposed tungsten layer. Of course the contaminant concentration is orders of magnitude higher after contamination of the implanter, but in addition our data show that different mechanisms are active in a not contaminated and in a contaminated implanter. A moderate tungsten contamination is observed also in a not contaminated implanter, however in that case contamination is completely not energetic and can be effectively screened by a very thin oxide. On the contrary, the contamination due to an implantation in a previously contaminated implanter is reduced but not suppressed even by a relatively thick screen oxide. The comparison with SRIM calculations confirms that the observed deep penetration of the contaminant cannot be explained by a plain sputtering mechanism.

  15. Operations manual for the plasma source ion implantation economics program

    SciTech Connect

    Bibeault, M.L.; Thayer, G.R.

    1995-10-01

    Plasma Source Ion Implantation (PSII) is a surface modification technique for metal. PSIICOSTMODEL95 is an EXCEL-based program that estimates the cost for implementing a PSII system in a manufacturing setting where the number of parts to be processed is over 5,000 parts per day and the shape of each part does not change from day to day. Overall, the manufacturing process must be very well defined and should not change. This document is a self-contained manual for PSIICOSTMODEL95. It assumes the reader has some general knowledge of the technical requirements for PSII. Configuration of the PSII process versus design is used as the methodology in PSIICOSTMODEL95. The reason behind this is twofold. First, the design process cannot be programmed into a computer when the relationships between design variables are not understood. Second, the configuration methodology reduces the number of assumptions that must be programmed into our software. Misuse of results are less likely to occur if the user has fewer assumptions to understand.

  16. A Manually Operated, Advance Off-Stylet Insertion Tool for Minimally Invasive Cochlear Implantation Surgery

    PubMed Central

    Kratchman, Louis B.; Schurzig, Daniel; McRackan, Theodore R.; Balachandran, Ramya; Noble, Jack H.; Webster, Robert J.; Labadie, Robert F.

    2014-01-01

    The current technique for cochlear implantation (CI) surgery requires a mastoidectomy to gain access to the cochlea for electrode array insertion. It has been shown that microstereotactic frames can enable an image-guided, minimally invasive approach to CI surgery called percutaneous cochlear implantation (PCI) that uses a single drill hole for electrode array insertion, avoiding a more invasive mastoidectomy. Current clinical methods for electrode array insertion are not compatible with PCI surgery because they require a mastoidectomy to access the cochlea; thus, we have developed a manually operated electrode array insertion tool that can be deployed through a PCI drill hole. The tool can be adjusted using a preoperative CT scan for accurate execution of the advance off-stylet (AOS) insertion technique and requires less skill to operate than is currently required to implant electrode arrays. We performed three cadaver insertion experiments using the AOS technique and determined that all insertions were successful using CT and microdissection. PMID:22851233

  17. A rabbit osteomyelitis model for the longitudinal assessment of early post-operative implant infections

    PubMed Central

    2013-01-01

    Background Implant infection is one of the most severe complications within the field of orthopaedic surgery, associated with an enormous burden for the healthcare system. During the last decades, attempts have been made to lower the incidence of implant-related infections. In the case of cemented prostheses, the use of antibiotic-containing bone cement can be effective. However, in the case of non-cemented prostheses, osteosynthesis and spinal surgery, local antibacterial prophylaxis is not a standard procedure. For the development of implant coatings with antibacterial properties, there is a need for a reliable animal model to evaluate the preventive capacity of such coatings during a specific period of time. Existing animal models generally present a limited follow-up, with a limited number of outcome parameters and relatively large animal numbers in multiple groups. Methods To represent an early post-operative implant infection, we established an acute tibial intramedullary nail infection model in rabbits by contamination of the tibial nail with 3.8 × 105 colony forming units of Staphylococcus aureus. Clinical, haematological and radiological parameters for infection were weekly assessed during a 6-week follow-up with post-mortem bacteriological and histological analyses. Results S. aureus implant infection was confirmed by the above parameters. A saline control group did not develop osteomyelitis. By combining the clinical, haematological, radiological, bacteriological and histological data collected during the experimental follow-up, we were able to differentiate between the control and the infected condition and assess the severity of the infection at sequential timepoints in a parameter-dependent fashion. Conclusion We herein present an acute early post-operative rabbit implant infection model which, in contrast to previously published models, combines improved in-time insight into the development of an implant osteomyelitis with a relatively low

  18. Magnification rate of digital panoramic radiographs and its effectiveness for pre-operative assessment of dental implants

    PubMed Central

    Kim, Y-K; Park, J-Y; Kim, S-G; Kim, J-S; Kim, J-D

    2011-01-01

    Objectives The purpose of this study was to determine the accuracy and effectiveness of digital panoramic radiographs for pre-operative assessment of dental implants. Methods We selected 86 patients (221 implants) and calculated the length of the planned implant based on the distance between a selection of critical anatomical structures and the alveolar crest using the scaling tools provided in the digital panoramic system. We analysed the magnification rate and the difference between the actual inserted implant length and planned implant length according to the location of the implant placement and the clarity of anatomical structures seen in the panoramic radiographs. Results There was no significant difference between the planned implant length and actual inserted implant length (P > 0.05). The magnification rate of the width and length of the inserted implants, seen in the digital panoramic radiographs, was 127.28 ± 13.47% and 128.22 ± 4.17%, respectively. The magnification rate of the implant width was largest in the mandibular anterior part and there was a significant difference in the magnification rate of the length of implants between the maxilla and the mandible (P < 0.05). When the clarity of anatomical structures seen in the panoramic radiographs is low, the magnification rate of the width of the inserted implants is significantly higher (P < 0.05), but there is no significant difference between the planned implant length and actual inserted implant length according to the clarity of anatomical structures (P < 0.05). Conclusions Digital panoramic radiography can be considered a simple, readily available and considerably accurate pre-operative assessment tool in the vertical dimension for dental implant therapy. PMID:21239569

  19. Active implantable medical device EMI assessment for wireless power transfer operating in LF and HF bands.

    PubMed

    Hikage, Takashi; Nojima, Toshio; Fujimoto, Hiroshi

    2016-06-21

    The electromagnetic interference (EMI) imposed on active implantable medical devices by wireless power transfer systems (WPTSs) is discussed based upon results of in vitro experiments. The purpose of this study is to present comprehensive EMI test results gathered from implantable-cardiac pacemakers and implantable cardioverter defibrillators exposed to the electromagnetic field generated by several WPTSs operating in low-frequency (70 kHz-460 kHz) and high-frequency (6.78 MHz) bands. The constructed in vitro experimental test system based upon an Irnich's flat torso phantom was applied. EMI test experiments are conducted on 14 types of WPTSs including Qi-compliant system and EV-charging WPT system mounted on current production EVs. In addition, a numerical simulation model for active implantable medical device (AIMD) EMI estimation based on the experimental test system is newly proposed. The experimental results demonstrate the risk of WPTSs emitting intermittent signal to affect the correct behavior of AIMDs when operating at very short distances. The proposed numerical simulation model is applicable to obtain basically the EMI characteristics of various types of WPTSs. PMID:27224201

  20. Active implantable medical device EMI assessment for wireless power transfer operating in LF and HF bands

    NASA Astrophysics Data System (ADS)

    Hikage, Takashi; Nojima, Toshio; Fujimoto, Hiroshi

    2016-06-01

    The electromagnetic interference (EMI) imposed on active implantable medical devices by wireless power transfer systems (WPTSs) is discussed based upon results of in vitro experiments. The purpose of this study is to present comprehensive EMI test results gathered from implantable-cardiac pacemakers and implantable cardioverter defibrillators exposed to the electromagnetic field generated by several WPTSs operating in low-frequency (70 kHz–460 kHz) and high-frequency (6.78 MHz) bands. The constructed in vitro experimental test system based upon an Irnich’s flat torso phantom was applied. EMI test experiments are conducted on 14 types of WPTSs including Qi-compliant system and EV-charging WPT system mounted on current production EVs. In addition, a numerical simulation model for active implantable medical device (AIMD) EMI estimation based on the experimental test system is newly proposed. The experimental results demonstrate the risk of WPTSs emitting intermittent signal to affect the correct behavior of AIMDs when operating at very short distances. The proposed numerical simulation model is applicable to obtain basically the EMI characteristics of various types of WPTSs.

  1. [Total elbow arthroplasty. Indications, operative technique and results after implantation of an Acclaim elbow prosthesis].

    PubMed

    Lerch, K; Tingart, M; Trail, I; Grifka, J

    2003-08-01

    Total elbow arthroplasty has become a reliable treatment option for patients with rheumatoid arthritis as well as primary or posttraumatic arthrosis. The aim of this study is to present the indications, operative technique and results for the implantation of an Acclaim elbow prosthesis. Case reports are given to demonstrate the indications for prosthesis implantation. Furthermore, the follow-up results are reported for 65 patients after implantation of an Acclaim prosthesis. Pre- and postoperative pain were evaluated using the visual analogue scale. The pain level decreased from 8.0 to 2.3 postoperatively. After implantation of an elbow prosthesis, there was a significant improvement in the range of motion. The mean flexion increased from 103 degrees preoperatively to 140 degrees postoperatively. An increase of 10 degrees was found for both supination and pronation. Complications included temporary ulnary nerve irritation in seven patients, intraoperative fractures in four cases and postoperative elbow dislocation in one case. In conclusion, total elbow arthroplasty results in a reduction of pain and an improvement in elbow movement. However, selection of the right patient is important. Patients are advised not to lift heavy objects or to perform hard physical work. If patients' compliance can not be ensured preoperatively, no total elbow arthroplasty should be performed. PMID:12955197

  2. Automatic pre- to intra-operative CT registration for image-guided cochlear implant surgery

    PubMed Central

    Reda, Fitsum A.; Noble, Jack H.; Labadie, Robert F.; Dawant, Benoit M.

    2015-01-01

    Percutaneous cochlear implantation (PCI) is a minimally invasive image-guided cochlear implant approach, where access to the cochlea is achieved by drilling a linear channel from the skull surface to the cochlea. The PCI approach requires pre- and intra-operative planning. Computation of a safe linear drilling trajectory is performed in a pre-operative CT. This trajectory is mapped to intra-operative space using the transformation matrix that registers the pre- and intra-operative CTs. However, the difference in orientation between the pre- and intra-operative CTs is too extreme to be recovered by standard, gradient descent based registration methods. Thus far, the registration has been initialized manually by an expert. In this work we present a method that aligns the scans completely automatically. We compared the performance of the automatic approach to the registration approach when an expert does the manual initialization on 11 pairs of scans. There is a maximum difference of 0.18 mm between the entry and target points of the trajectory mapped with expert initialization and the automatic registration method. This suggests that the automatic registration method is accurate enough to be used in a PCI surgery. PMID:22922692

  3. Pre-operative simulation and post-operative validation of soft-tissue deformations for breast implantation planning

    NASA Astrophysics Data System (ADS)

    Roose, Liesbet; De Maerteleire, Wim; Mollemans, Wouter; Maes, Frederik; Suetens, Paul

    2006-03-01

    Virtual surgery simulation plays an increasingly important role as a planning aid for the surgeon. A reliable simulation method to predict the surgical outcome of breast reconstruction and breast augmentation procedures does not yet exist. However, a method to pre-operatively assess the result of the procedure would be useful to ensure a symmetrical and naturally looking result, and could be a practical means of communication with the patient. In this paper, we present a basic framework to simulate a subglandular breast implantation. First, we propose a method to build a model of the patient's anatomy, based on a 3D picture of the skin surface in combination with thickness estimates of the soft tissue surrounding the breast. This approach is cheap, fast and the picture can be taken while the patient is standing upright, which makes it advantageous compared to conventional CTor MR-based methods. Second, a set of boundary conditions is defined to mimic the effect of the implant. Finally, we compute the new equilibrium geometry using the iterative FEM-based Mass Tensor Method, which is computationally more effcient than the traditional FEM approach since sufficient precision can be achieved with a limited number of iterations. We illustrate our approach with a preliminary validation study on 4 patients. We obtain promising results with a mean error between the simulated and the true post-operative breast geometry below 4 mm and maximal error below 10 mm, which is found to be sufficiently accurate for visual assessment in clinical practice.

  4. Minimally Invasive Catheter Procedures to Assist Complicated Pacemaker Lead Extraction and Implantation in the Operating Room

    SciTech Connect

    Kroepil, Patric; Lanzman, Rotem S. Miese, Falk R.; Blondin, Dirk; Winter, Joachim; Scherer, Axel; Fuerst, Guenter

    2011-04-15

    We report on percutaneous catheter procedures in the operating room (OR) to assist complicated manual extraction or insertion of pacemaker (PM) and implantable cardioverter defibrillator leads. We retrospectively reviewed complicated PM revisions and implantations performed between 2004 and 2009 that required percutaneous catheter procedures performed in the OR. The type of interventional procedure, catheter and retrieval system used, venous access, success rates, and procedural complications were analyzed. In 41 (12 female and 29 male [mean age 62 {+-} 17 years]) of 3021 (1.4%) patients, standard manual retrieval of old leads or insertion of new leads was not achievable and thus required percutaneous catheter intervention for retrieval of misplaced leads and/or recanalisation of occluded central veins. Thirteen of 18 (72.2%) catheter-guided retrieval procedures for misplaced (right atrium [RA] or ventricle [RV; n = 3], superior vena cava [n = 2], brachiocephalic vein [n = 5], and subclavian vein [n = 3]) lead fragments in 16 patients were successful. Percutaneous catheter retrieval failed in five patients because there were extremely fixed or adhered lead fragments. Percutaneous transluminal angiography (PTA) of central veins for occlusion or high-grade stenosis was performed in 25 patients. In 22 of 25 patients (88%), recanalization of central veins was successful, thus enabling subsequent lead replacement. Major periprocedural complications were not observed. In the case of complicated manual PM lead implantation or revision, percutaneous catheter-guided extraction of misplaced lead fragments or recanalisation of central veins can be performed safely in the OR, thus enabling subsequent implantation or revision of PM systems in the majority of patients.

  5. Scaling up delivery of contraceptive implants in sub-Saharan Africa: operational experiences of Marie Stopes International

    PubMed Central

    Duvall, Susan; Thurston, Sarah; Weinberger, Michelle; Nuccio, Olivia; Fuchs-Montgomery, Nomi

    2014-01-01

    Contraceptive implants offer promising opportunities for addressing the high and growing unmet need for modern contraceptives in sub-Saharan Africa. Marie Stopes International (MSI) offers implants as one of many family planning options. Between 2008 and 2012, MSI scaled up voluntary access to implants in 15 sub-Saharan African countries, from 80,041 implants in 2008 to 754,329 implants in 2012. This 9-fold increase amounted to more than 1.7 million implants delivered cumulatively over the 5-year period. High levels of client satisfaction were attained alongside service provision scale up by using existing MSI service delivery channels—mobile outreach, social franchising, and clinics—to implement strategies that broadened access for underserved clients and maintained service quality. Use of adaptive and context-specific service delivery models and attention to key operational components, including sufficient numbers of trained providers, strong supply chains, diverse financing mechanisms, and implant removal services, underpinned our service delivery efforts. Accounting for 70% of the implants delivered by MSI in 2012, mobile outreach services through dedicated MSI provider teams played a central role in scale-up efforts, fueled in part by the provision of free or heavily subsidized services. Social franchising also demonstrated promise for future program growth, along with MSI clinics. Continued high growth in implant provision between 2011 and 2012 in all sub-Saharan African countries indicates the region's capacity for further service delivery expansion. Meeting the expected rising demand for implants and ensuring long-term sustainable access to the method, as part of a comprehensive method mix, will require continued use of appropriate service delivery models, effective operations, and ongoing collaboration between the private, public, and nongovernmental sectors. MSI's experience can be instructive for future efforts to ensure contraceptive access and

  6. PRE-OPERATIVE HEALTH STATUS AND OUTCOMES FOLLOWING CONTINUOUS-FLOW LEFT VENTRICULAR ASSIST DEVICE IMPLANTATION

    PubMed Central

    Flint, Kelsey M.; Matlock, Daniel D.; Sundareswaran, Kartik; Lindenfeld, JoAnn; Spertus, John A.; Farrar, David J.; Allen, Larry A.

    2013-01-01

    Background Health status predicts adverse outcomes in heart failure and cardiac surgery patients, but its prognostic value in left ventricular assist device (LVAD) placement is unknown. Methods We examined the association of pre-operative health status, as measured by the Kansas City Cardiomyopathy Questionnaire (KCCQ), with survival and hospitalization after LVAD using KCCQ as a continuous variable and stratified by KCCQ score quartile plus missing KCCQ in 1125 clinical trial participants receiving the HeartMate II as either destination therapy (n=635) or bridge to transplantation (n=490). Results Mean pre-operative KCCQ score was 29.4±18.7 among survivors (n=719), and 27.1±18.3 (n=406) in those who died. In time-to-event analysis for all available follow up using health status as a continuous variable, pre-operative KCCQ score did not correlate with overall mortality after LVAD implantation (p=0.178). Small absolute differences were seen between pre-operative KCCQ quartile and 30-day survival (Q4 95% vs. Q1 89% vs. missing 87%; p=0.0009 for trend), 180-day survival (Q4 83% vs. Q1 76% vs. missing 79%; p=0.060 for trend), and days hospitalized at 180 days (Q4 29.8±25.6 vs. Q1 34.1±27.1 vs. missing 36.5±29.9; p=0.009 for trend). Conclusion Our findings suggest that pre-operative health status has limited association with outcomes after LVAD implantation. Although these data require further study in a diverse population, mechanical circulatory support may represent a relatively unique clinical situation, distinct from heart failure and other cardiac surgeries, in which heart failure-specific health status measures may be largely reversed. PMID:24119729

  7. Eddy current inspection tool which is selectively operable in a discontinuity detection mode and a discontinuity magnitude mode

    DOEpatents

    Petrini, R.R.; Van Lue, D.F.

    1983-10-25

    A miniaturized inspection tool, for testing and inspection of metal objects in locations with difficult accessibility, which comprises eddy current sensing equipment with a probe coil, and associated coaxial coil cable, coil energizing means, and circuit means responsive to impedance changes in the coil as effected by induced eddy currents in a test object to produce a data output signal proportional to such changes. The coil and cable are slideably received in the utility channel of the flexible insertion tube of fiberoptic scope. The scope is provided with light transmitting and receiving fiberoptics for viewing through the flexible tube, and articulation means for articulating the distal end of the tube and permitting close control of coil placement relative to a test object. The eddy current sensing equipment includes a tone generator 30 for generating audibly signals responsive to the data output signal. In one selected mode of operation, the tone generator responsive to the output signal above a selected level generates a constant single frequency tone for signaling detection of a discontinuity and, in a second selected mode, generates a tone whose frequency is proportional to the difference between the output signal and a predetermined selected threshold level. 5 figs.

  8. Eddy current inspection tool which is selectively operable in a discontinuity detection mode and a discontinuity magnitude mode

    DOEpatents

    Petrini, Richard R.; Van Lue, Dorin F.

    1983-01-01

    A miniaturized inspection tool, for testing and inspection of metal objects in locations with difficult accessibility, which comprises eddy current sensing equipment (12) with a probe coil (11), and associated coaxial coil cable (13), coil energizing means (21), and circuit means (21, 12) responsive to impedance changes in the coil as effected by induced eddy currents in a test object to produce a data output signal proportional to such changes. The coil and cable are slideably received in the utility channel of the flexible insertion tube 17 of fiberoptic scope 10. The scope 10 is provided with light transmitting and receiving fiberoptics for viewing through the flexible tube, and articulation means (19, 20) for articulating the distal end of the tube and permitting close control of coil placement relative to a test object. The eddy current sensing equipment includes a tone generator 30 for generating audibly signals responsive to the data output signal. In one selected mode of operation, the tone generator responsive to the output signal above a selected level generates a constant single frequency tone for signalling detection of a discontinuity and, in a second selected mode, generates a tone whose frequency is proportional to the difference between the output signal and a predetermined selected threshold level.

  9. [Frequency-specific analysis of the hVOR Prior of Cochlear Implant Operation].

    PubMed

    Hülse, R; Hülse, M; Wenzel, A; Hörmann, K; Servais, J J

    2015-03-01

    Dizziness is one of the most common postoperative complications after a cochlear-implant (CI) surgery. With our prospective, matched-paired controlled study, we could demonstrate that patients with distinctive sensorineural hearing loss--even without any complaints of dizziness--already have a reduced horizontal vestibular-ocular-reflex (hVOR). Compared to controls, CI patients presented with a significantly reduced gain. 9 out of 17 CI patients showed physiological results in rotatory testing and video head thrust testing. One patient presented with pathological results in both tests. Remarkably, there were 2 patients who presented with pathological head impulse testing but normal values in rotatory testing and 5 patients who showed normal gains in video head impulse testing but abnormal rotatory tests. These findings clearly show the importance of a differentiated, frequency-dependent pre-operative vestibular assessment including rotatory testing and video-head impulse testing. Additionally, only an accurate pre-operative vestibular testing allows evaluating possible post-operative dizziness related complications and should be documented precisely, also for forensic reasons. This is the key to differentiate post-operative dizziness from an pre-operatively existing vestibular disorder that possibly might not be clinically apparent by the time of testing. PMID:25265227

  10. Poly Implant Prothèse™ (PIP) experience in the United Kingdom: A prospective cohort study into the accuracy of diagnostic imaging findings in comparison to operative findings of 1029 implants.

    PubMed

    Leckenby, Jonathan; Chana, Jagdeep; Harrison, Douglas; Grobbelaar, Adriaan

    2016-04-01

    The Poly Implant Prosthèse™ (PIP) implants were withdrawn from market use in the United Kingdom on 31st March 2010 following Government issued advice. In June 2012 a final Government report was issued and during this period the majority of patients elected to have their prostheses removed. This study presents the operative findings of three surgeons. 517 patients were identified retrospectively from the implant database as having received PIP implants with a total of 1029 implants. 62 patients (124 implants) declined explantation after consultation and imaging. The data was recorded prospectively for all patients and included the clinical, imaging and operative findings. A total of 905 implants were removed of which 129 were ruptured at the time of explantation (14.25%). 27 implants were intact but the presence of liquid surrounding the prosthesis was noted. 93 implants were reported as being ruptured after diagnostic imaging but were intact operatively resulting in a test sensitivity of 0.82 and a specificity of 0.92 yielding a positive predictive value of 0.59 and a negative predictive value of 0.97 overall. Capsule formation was noted in 27 breasts (3%). Our study showed that the prevalence of PIP ruptures is comparable to other manufacturers. The prevalence of implant rupture predictably increased over time and the prevalence of abnormal capsule formation was similar to other manufacturers. PMID:26936318

  11. Intra-operative Iodine-125 prostatic implant following bilateral pelvic lymphadenectomy

    SciTech Connect

    Kwong, E.W.H.; Huh, S.H.; Nobler, M.P.; Smith, H.S.

    1984-05-01

    Sixty-five patients with prostatic adenocarcinoma Stages B and C were treated with intraoperative Iodine-125 prostatic implantation following bilateral pelvic lymphadenectomy. Pelvic nodal metastases were found in 31% of the patients. All the patients have been followed for a period of 1 1/2 to 6 years. Serial digital rectal examination revealed complete regression of the palpable disease in 15% of the patients at 6 months, 47% at 1 year, and 87% at 2 years. Post-operative complications were also evaluated: 13% of the patients became sexually impotent, 11% had impaired potency after the procedure, and 26% of patients complained of dry ejaculation; and 17% developed scrotal and/or penile swelling, which persisted up to 14 months, but usually subsided within 5 months. Two patients developed local recurrence.

  12. Comparison of implant quality between loose and intra-operatively linked iodine-125 seeds in prostate cancer brachytherapy.

    PubMed

    Jarusevicius, Laimonas; Inciura, Arturas; Juozaityte, Elona; Vaiciunas, Kestutis; Vaitkus, Antanas; Sniureviciute, Migle

    2012-01-01

    From 2007 to 2010, 230 patients had iodine-125 seeds implanted (loose or intra-operatively linked into seed trains with variable seed-to-seed spacing). The primary aim was to evaluate differences in implant quality by comparing the intra-operative and post-implant dosimetry in patients treated with loose and intra-operatively linked seeds. The secondary aim was to evaluate the "learning curve" for the procedure. The following parameters were compared: the radiation dose to 90% of the prostate volume (D90), the radiation dose to 30% of the urethral volume (DU30), the percentage of the prostate volume receiving 100% or 200% of the prescribed dose (V100 or V200, respectively), the percentage of the rectal volume receiving 100% of the prescribed dose (VR100), and the homogeneity index (HI). We obtained the following results for loose vs. intra-operatively linked seeds: D90 (Gy), 184.7 ± 15.0 vs. 177.9 ± 12.7 (p = 0.002); V100 (%), 95.5 ± 2.4 vs. 94.9 ± 3.2 (p = 0.206); V200 (%), 35.1 ± 7.5 vs. 24.3 plusmn; 6,9 (p < 0.001); DU30 (Gy), 218.6 ± 24.1 vs. 197.4 ± 19.5 (p = 0.001); VR100 (cm³), 0.6 ± 0.47 vs. 0.3 ± 0.3 (p < 0.001); HI (%), 31.8 ± 7.3 vs. 44.0 ± 9.8 (p < 0.001). The advantages of intra-operatively linked seed implantation over loose seed implantation are a more homogeneous prostate dose and lower urethral and rectal doses. The disadvantage is a lower post-implant D90. Sufficient experience with the loose seed implantation procedure was obtained after the first 40 patients. There was essentially no learning curve when a new implantation method using intra-operatively linked seeds was subsequently initiated. PMID:22739013

  13. A standard operating procedure for the surgical implantation of transmitters in juvenile salmonids

    USGS Publications Warehouse

    Liedtke, T.L.; Beeman, J.W.; Gee, L.P.

    2012-01-01

    Biotelemetry is a useful tool to monitor the movements of animals and is widely applied in fisheries research. Radio or acoustic technology can be used, depending on the study design and the environmental conditions in the study area. A broad definition of telemetry also includes the use of Passive Integrated Transponder (PIT) tags, either separately or with a radio or acoustic transmitter. To use telemetry, fish must be equipped with a transmitter. Although there are several attachment procedures available, surgical implantation of transmitters in the abdominal cavity is recognized as the best technique for long-term telemetry studies in general (Stasko and Pincock, 1977; Winter, 1996; Jepsen, 2003), and specifically for juvenile salmonids, Oncorhynchus spp. (Adams and others, 1998a, 1998b; Martinelli and others, 1998; Hall and others, 2009). Studies that use telemetry assume that the processes by which the animals are captured, handled, and tagged, as well as the act of carrying the transmitter, will have minimal effect on their behavior and performance. This assumption, commonly stated as a lack of transmitter effects, must be valid if telemetry studies are to describe accurately the movements and behavior of an entire population of interest, rather than the subset of that population that carries transmitters. This document describes a standard operating procedure (SOP) for surgical implantation of radio or acoustic transmitters in juvenile salmonids. The procedures were developed from a broad base of published information, laboratory experiments, and practical experience in tagging thousands of fish for numerous studies of juvenile salmon movements near Columbia River and Snake River hydroelectric dams. Staff from the Western Fisheries Research Center's Columbia River Research Laboratory (CRRL) frequently have used telemetry studies to evaluate new structures or operations at hydroelectric dams in the Columbia River Basin, and these evaluations typically

  14. Harms and responsibilities associated with battery-operated implants (BOI): who controls postmortem explantation?

    PubMed

    Bramstedt, Katrina A

    2013-01-01

    The postmortem issues raised by battery-operated implants (BOI) are complex and issues of consent, setting (clinical vs research), and environmental risks have received little attention in bioethics literature. Analyzing the issues, the following are argued: (1) Patients receiving BOIs should sign a consent form that includes a requirement for postmortem explant of the device; (2) BOI consent forms should require the explanted devices be returned to their manufacturers for Returned Product Analysis; (3) Failure to explant and analyze devices from the research setting fails the research goal of generation of knowledge for the benefit of future patients; (4) Failure to explant and analyze devices from the clinical setting allows product defects to be potentially hidden from patients, families, clinicians, manufacturers, and regulatory agencies; (5) Bodies buried with BOIs potentially harm the environment; (6) Religious or philosophical objections to autopsy should not supersede the duty to explant and analyze BOIs; (7) The concepts herein for BOIs could potentially extend to non-BOI if the device has failure modes that can lead to a potentially life-threatening event or can cause permanent debilitating health issues, and the burial or cremation of the device poses environmental harm. In these situations, neither the patient (premortem) nor family (postmortem) should have the right to refuse explant. PMID:23121647

  15. Radiation exposure to operator and patients during cardiac electrophysiology study, radiofrequency catheter ablation and cardiac device implantation procedures

    NASA Astrophysics Data System (ADS)

    Lee, C. H.; Cho, J. H.; Park, S. J.; Kim, J. S.; On, Y. K.; Huh, J.

    2015-10-01

    The purpose of this study was to measure the radiation exposure to operator and patient during cardiac electrophysiology study, radiofrequency catheter ablation and cardiac device implantation procedures and to calculate the allowable number of cases per year. We carried out 9 electrophysiology studies, 40 radiofrequency catheter ablation and 11 cardiac device implantation procedures. To measure occupational radiation dose and dose-area product (DAP), 13 photoluminescence glass dosimeters were placed at eyes (inside and outside lead glass), thyroids (inside and outside thyroid collar), chest (inside and outside lead apron), wrists, genital of the operator (inside lead apron), and 6 of photoluminescence glass dosimeters were placed at eyes, thyroids, chest and genital of the patient. Exposure time and DAP values were 11.7 ± 11.8 min and 23.2 ± 26.2 Gy cm2 for electrophysiology study; 36.5 ± 42.1 min and 822.4 ± 125.5 Gy cm2 for radiofrequency catheter ablation; 16.2 ± 9.3 min and 27.8 ± 16.5 Gy cm2 for cardiac device implantation procedure, prospectively. 4591 electrophysiology studies can be conducted within the occupational exposure limit for the eyes (150 mSv), and 658-electrophysiology studies with radiofrequency catheter ablation can be carried out within the occupational exposure limit for the hands (500 mSv). 1654 cardiac device implantation procedure can be conducted within the occupational exposure limit for the eyes (150 mSv). The amounts of the operator and patient's radiation exposure were comparatively small. So, electrophysiology study, radio frequency catheter ablation and cardiac device implantation procedures are safe when performed with modern equipment and optimized protective radiation protect equipment.

  16. Initial operation of a large-scale Plasma Source Ion Implantation experiment

    SciTech Connect

    Wood, B.P.; Henins, I.; Gribble, R.J.; Reass, W.A.; Faehl, R.J.; Nastasi, M.A.; Rej, D.J.

    1993-10-01

    In Plasma Source Ion Implantation (PSII), a workpiece to be implanted is immersed in a weakly ionized plasma and pulsed to a high negative voltage. Plasma ions are accelerated toward the workpiece and implanted in its surface. Experimental PSII results reported in the literature have been for small workpieces. A large scale PSII experiment has recently been assembled at Los Alamos, in which stainless steel and aluminum workpieces with surface areas over 4 m{sup 2} have been implanted in a 1.5 m-diameter, 4.6 m-length cylindrical vacuum chamber. Initial implants have been performed at 50 kV with 20 {mu}s pulses of 53 A peak current, repeated at 500 Hz, although the pulse modulator will eventually supply 120 kV pulses of 60 A peak current at 2 kHz. A 1,000 W, 13.56 MHz capacitively-coupled source produces nitrogen plasma densities in the 10{sup 15} m{sup {minus}3} range at neutral pressures as low as 0.02 mtorr. A variety of antenna configurations have been tried, with and without axial magnetic fields of up to 60 gauss. Measurements of sheath expansion, modulator voltage and current, and plasma density fill-in following a pulse are presented. The authors consider secondary electron emission, x-ray production, workpiece arcing, implant conformality, and workpiece and chamber heating.

  17. Task Shifting Provision of Contraceptive Implants to Community Health Extension Workers: Results of Operations Research in Northern Nigeria

    PubMed Central

    Oguntunde, Olugbenga; Orobaton, Nosa; Otolorin, Emmanuel; Inuwa, Fatima; Alalade, Olubisi; Abegunde, Dele; Danladi, Saba’atu

    2015-01-01

    Background: Contraceptive use remains low in Nigeria, with only 11% of women reporting use of any modern method. Access to long-acting reversible contraceptives (LARCs) is constrained by a severe shortage of human resources. To assess feasibility of task shifting provision of implants, we trained community health extension workers (CHEWs) to insert and remove contraceptive implants in rural communities of Bauchi and Sokoto states in northern Nigeria. Methods: We conducted 2- to 3-week training sessions for 166 selected CHEWs from 82 facilities in Sokoto state (September 2013) and 84 health facilities in Bauchi state (December 2013). To assess feasibility of the task shifting approach, we conducted operations research using a pretest–posttest design using multiple sources of information, including surveys with 151 trained CHEWs (9% were lost to follow-up) and with 150 family planning clients; facility observations using supply checklists (N = 149); direct observation of counseling provided by CHEWs (N = 144) and of their clinical (N = 113) skills; as well as a review of service statistics (N = 151 health facilities). The endline assessment was conducted 6 months after the training in each state. Results: CHEWs inserted a total of 3,588 implants in 151 health facilities over a period of 6 months, generating 10,088 couple-years of protection (CYP). After practicing on anatomic arm models, most CHEWs achieved competency in implant insertions after insertions with 4–5 actual clients. Clinical observations revealed that CHEWs performed implant insertion tasks correctly 90% of the time or more for nearly all checklist items. The amount of information that CHEWs provided clients increased between baseline and endline, and over 95% of surveyed clients reported being satisfied with CHEWs’ services in both surveys. The study found that supervisors not only observed and corrected insertion skills, as needed, during supervisory visits but also encouraged

  18. Reliable experimental setup to test the pressure modulation of Baerveldt Implant tubes for reducing post-operative hypotony

    NASA Astrophysics Data System (ADS)

    Ramani, Ajay

    Glaucoma encompasses a group of conditions that result in damage to the optic nerve and can cause loss of vision and blindness. The nerve is damaged due to an increase in the eye's internal (intraocular) pressure (IOP) above the nominal range of 15 -- 20 mm Hg. There are many treatments available for this group of diseases depending on the complexity and stage of nerve degradation. In extreme cases where drugs or laser surgery do not create better conditions for the patient, ophthalmologists use glaucoma drainage devices to help alleviate the IOP. Many drainage implants have been developed over the years and are in use; but two popular implants are the Baerveldt Glaucoma Implant and the Ahmed Glaucoma Valve Implant. Baerveldt Implants are non-valved and provide low initial resistance to outflow of fluid, resulting in post-operative complications such as hypotony, where the IOP drops below 5 mm of Hg. Ahmed Glaucoma Valve Implants are valved implants which initially restrict the amount of fluid flowing out of the eye. The long term success rates of Baerveldt Implants surpass those of Ahmed Valve Implants because of post-surgical issues; but Baerveldt Implants' initial effectiveness is poor without proper flow restriction. This drives the need to develop new ways to improve the initial effectiveness of Baerveldt Implants. A possible solution proposed by our research team is to place an insert in the Baerveldt Implant tube of inner diameter 305 microns. The insert must be designed to provide flow resistance for the early time frame [e.g., first 30 -- 60 post-operative days] until sufficient scar tissue has formed on the implant. After that initial stage with the insert, the scar tissue will provide the necessary flow resistance to maintain the IOP above 5 mm Hg. The main objective of this project was to develop and validate an experimental apparatus to measure pressure drop across a Baerveldt Implant tube, with and without inserts. This setup will be used in the

  19. Automaticity of Conceptual Magnitude.

    PubMed

    Gliksman, Yarden; Itamar, Shai; Leibovich, Tali; Melman, Yonatan; Henik, Avishai

    2016-01-01

    What is bigger, an elephant or a mouse? This question can be answered without seeing the two animals, since these objects elicit conceptual magnitude. How is an object's conceptual magnitude processed? It was suggested that conceptual magnitude is automatically processed; namely, irrelevant conceptual magnitude can affect performance when comparing physical magnitudes. The current study further examined this question and aimed to expand the understanding of automaticity of conceptual magnitude. Two different objects were presented and participants were asked to decide which object was larger on the screen (physical magnitude) or in the real world (conceptual magnitude), in separate blocks. By creating congruent (the conceptually larger object was physically larger) and incongruent (the conceptually larger object was physically smaller) pairs of stimuli it was possible to examine the automatic processing of each magnitude. A significant congruity effect was found for both magnitudes. Furthermore, quartile analysis revealed that the congruity was affected similarly by processing time for both magnitudes. These results suggest that the processing of conceptual and physical magnitudes is automatic to the same extent. The results support recent theories suggested that different types of magnitude processing and representation share the same core system. PMID:26879153

  20. Automaticity of Conceptual Magnitude

    PubMed Central

    Gliksman, Yarden; Itamar, Shai; Leibovich, Tali; Melman, Yonatan; Henik, Avishai

    2016-01-01

    What is bigger, an elephant or a mouse? This question can be answered without seeing the two animals, since these objects elicit conceptual magnitude. How is an object’s conceptual magnitude processed? It was suggested that conceptual magnitude is automatically processed; namely, irrelevant conceptual magnitude can affect performance when comparing physical magnitudes. The current study further examined this question and aimed to expand the understanding of automaticity of conceptual magnitude. Two different objects were presented and participants were asked to decide which object was larger on the screen (physical magnitude) or in the real world (conceptual magnitude), in separate blocks. By creating congruent (the conceptually larger object was physically larger) and incongruent (the conceptually larger object was physically smaller) pairs of stimuli it was possible to examine the automatic processing of each magnitude. A significant congruity effect was found for both magnitudes. Furthermore, quartile analysis revealed that the congruity was affected similarly by processing time for both magnitudes. These results suggest that the processing of conceptual and physical magnitudes is automatic to the same extent. The results support recent theories suggested that different types of magnitude processing and representation share the same core system. PMID:26879153

  1. Short-term post-operative pain and discomfort following insertion of mini-implants for retaining mandibular overdentures: a randomized controlled trial.

    PubMed

    Ribeiro, A B; Della Vecchia, M P; Cunha, T R; Sorgini, D B; Dos Reis, A C; Muglia, V A; de Albuquerque, R F; de Souza, R F

    2015-08-01

    The retention of removable dentures by mini-implants is a relatively recent treatment modality and may lead to minimal post-operative trauma. This study compared post-operative pain and discomfort following the insertion of mini-implants (two or four) or two standard-size implants for the retention of mandibular overdentures. One hundred and twenty edentulous participants (mean age 59.5 ± 8.5 years) were randomly allocated into three groups according to received treatment: (GI) four mini-implants, (GII) two mini-implants or (GIII) two standard implants. Seven days after implant insertion, patients answered questions (100-mm VAS) relating to pain, swelling, and discomfort with chewing, speech and hygiene, considering their experiences during the 1st and 6th day. Groups were compared by two-way anova (α = 0.05). All participants (GI: 38; GII: 42; GIII: 40) were analysed after 7 days. At the 6th day, GI felt significantly higher pain than GII and GIII. GI also reported more difficulty in performing oral hygiene practices than GIII during the 1st day. There was no significant difference between groups for the other questions and periods. No participant suffered unexpected side effects. The use of four mini-implants induces more intense post-operative pain at the 6th day than the insertion of two mini- or conventional fixtures, as well as more difficult oral hygiene on the 1st day. Clinicaltrials.gov, NCT01411683; FAPESP, 2011/00688-7 and 2011/23347-0. PMID:25765784

  2. New operational techniques of implantation of biomaterials and titanium implants in the jaw with the atrophy of the bone and soft tissues

    NASA Astrophysics Data System (ADS)

    Nikityuk, D. B.; Urakov, A. L.; Reshetnikov, A. P.; Kopylov, M. V.; Baimurzin, D. Yu.

    2015-11-01

    The research into dynamics of quality of clinical use in 2003 - 2012 of autologous and xenogeneic biomaterials at dental transplantation and implantation among 1,100 of adult patients was made. The analysis results show that at autologous bone transplantation implant survival is observed only in 72% of cases, and the "necessary" result of bone repair occurred only in 6 - 9 months. Transplantation of biomaterials of OsteoBiol® (materials "mp3", "Genos" and "Evolution") provided engraftment and bone regeneration in 100 % of cases and allowed the use of dental implantation immediately after transplantation even in case of reduction in the patient's alveolar crest down to 2.0 mm. Replace Select implants of Nobel Biocare® were used at plantation. In order to exclude Schneiderian membrane's perforation lighting of Highmore's sinus with the cold blue-violet light from inside at sinus elevation is recommended as well as deepening of dental instruments into the bone only until the blue-violet light appears under them. To exclude deficiency of soft tissue under the cervical part of the ceramic crown application of special anti-fissure technology involving biomaterial flap dissection and its laying around the implant is suggested.

  3. System design and operation of a 100 kilovolt, 2 kilohertz pulse modulator for plasma source ion implantation

    SciTech Connect

    Reass, W.A.

    1994-07-01

    This paper describes the electrical design and operation of a high power modulator system implemented for the Los Alamos Plasma Source Ion Implantation (PSII) facility. To test the viability of the PSII process for various automotive components, the modulator must accept wide variations of load impedance. Components have varying area and composition which must be processed with different plasmas. Additionally, the load impedance may change by large factors during the typical 20 uS pulse, due to plasma displacement currents and sheath growth. As a preliminary design to test the system viability for automotive component implantation, suitable for a manufacturing environment, circuit topology must be able to directly scale to high power versions, for increased component through-put. We have chosen an evolutionary design approach with component families of characterized performance, which should Ion result in a reliable modulator system with component lifetimes. The modulator utilizes a pair of Litton L-3408 hollow beam amplifier tubes as switching elements in a ``hot-deck`` configuration. Internal to the main of planar triode hot deck, an additional pair decks, configured in a totem pole circuit, provide input drive to the L-3408 mod-anodes. The modulator can output over 2 amps average current (at 100 kV) with 1 kW of modanode drive. Diagnostic electronics monitor the load and stops pulses for 100 mS when a load arcs occur. This paper, in addition to providing detailed engineering design information, will provide operational characteristics and reliability data that direct the design to the higher power, mass production line capable modulators.

  4. Are Earthquake Magnitudes Clustered?

    SciTech Connect

    Davidsen, Joern; Green, Adam

    2011-03-11

    The question of earthquake predictability is a long-standing and important challenge. Recent results [Phys. Rev. Lett. 98, 098501 (2007); ibid.100, 038501 (2008)] have suggested that earthquake magnitudes are clustered, thus indicating that they are not independent in contrast to what is typically assumed. Here, we present evidence that the observed magnitude correlations are to a large extent, if not entirely, an artifact due to the incompleteness of earthquake catalogs and the well-known modified Omori law. The latter leads to variations in the frequency-magnitude distribution if the distribution is constrained to those earthquakes that are close in space and time to the directly following event.

  5. Misconceptions about astronomical magnitudes

    NASA Astrophysics Data System (ADS)

    Schulman, Eric; Cox, Caroline V.

    1997-10-01

    The present system of astronomical magnitudes was created as an inverse scale by Claudius Ptolemy in about 140 A.D. and was defined to be logarithmic in 1856 by Norman Pogson, who believed that human eyes respond logarithmically to the intensity of light. Although scientists have known for some time that the response is instead a power law, astronomers continue to use the Pogson magnitude scale. The peculiarities of this system make it easy for students to develop numerous misconceptions about how and why to use magnitudes. We present a useful exercise in the use of magnitudes to derive a cosmologically interesting quantity (the mass-to-light ratio for spiral galaxies), with potential pitfalls pointed out and explained.

  6. Turning an organic semiconductor into a low-resistance material by ion implantation

    NASA Astrophysics Data System (ADS)

    Fraboni, Beatrice; Scidà, Alessandra; Cosseddu, Piero; Wang, Yongqiang; Nastasi, Michael; Milita, Silvia; Bonfiglio, Annalisa

    2015-12-01

    We report on the effects of low energy ion implantation on thin films of pentacene, carried out to investigate the efficacy of this process in the fabrication of organic electronic devices. Two different ions, Ne and N, have been implanted and compared, to assess the effects of different reactivity within the hydrocarbon matrix. Strong modification of the electrical conductivity, stable in time, is observed following ion implantation. This effect is significantly larger for N implants (up to six orders of magnitude), which are shown to introduce stable charged species within the hydrocarbon matrix, not only damage as is the case for Ne implants. Fully operational pentacene thin film transistors have also been implanted and we show how a controlled N ion implantation process can induce stable modifications in the threshold voltage, without affecting the device performance.

  7. A pre-operative planning for endoprosthetic human tracheal implantation: a decision support system based on robust design of experiments.

    PubMed

    Trabelsi, O; Villalobos, J L López; Ginel, A; Cortes, E Barrot; Doblaré, M

    2014-05-01

    Swallowing depends on physiological variables that have a decisive influence on the swallowing capacity and on the tracheal stress distribution. Prosthetic implantation modifies these values and the overall performance of the trachea. The objective of this work was to develop a decision support system based on experimental, numerical and statistical approaches, with clinical verification, to help the thoracic surgeon in deciding the position and appropriate dimensions of a Dumon prosthesis for a specific patient in an optimal time and with sufficient robustness. A code for mesh adaptation to any tracheal geometry was implemented and used to develop a robust experimental design, based on the Taguchi's method and the analysis of variance. This design was able to establish the main swallowing influencing factors. The equations to fit the stress and the vertical displacement distributions were obtained. The resulting fitted values were compared to those calculated directly by the finite element method (FEM). Finally, a checking and clinical validation of the statistical study were made, by studying two cases of real patients. The vertical displacements and principal stress distribution obtained for the specific tracheal model were in agreement with those calculated by FE simulations with a maximum absolute error of 1.2 mm and 0.17 MPa, respectively. It was concluded that the resulting decision support tool provides a fast, accurate and simple tool for the thoracic surgeon to predict the stress state of the trachea and the reduction in the ability to swallow after implantation. Thus, it will help them in taking decisions during pre-operative planning of tracheal interventions. PMID:23046526

  8. Mechanical Behaviour of Umbrella-Shaped, Ni-Ti Memory Alloy Femoral Head Support Device during Implant Operation: A Finite Element Analysis Study

    PubMed Central

    Yi, Wei; Tian, Qing; Dai, Zhipeng; Liu, Xiaohu

    2014-01-01

    A new instrument used for treating femoral head osteonecrosis was recently proposed: the umbrella-shaped, Ni-Ti memory femoral head support device. The device has an efficacy rate of 82.35%. Traditional radiographic study provides limited information about the mechanical behaviour of the support device during an implant operation. Thus, this study proposes a finite element analysis method, which includes a 3-step formal head model construction scheme and a unique material assignment strategy for evaluating mechanical behaviour during an implant operation. Four different scenarios with different constraints, initial positions and bone qualities are analyzed using the simulation method. The max radium of the implanted device was consistent with observation data, which confirms the accuracy of the proposed method. To ensure that the device does not unexpectedly open and puncture the femoral head, the constraint on the impact device should be strong. The initial position of sleeve should be in the middle to reduce the damage to the decompression channel. The operation may fail because of poor bone quality caused by severe osteoporosis. The proposed finite element analysis method has proven to be an accurate tool for studying the mechanical behaviour of umbrella-shaped, Ni-Ti memory alloy femoral head support device during an implant operation. The 3-step construct scheme can be implemented with any kind of bone structure meshed with multiple element types. PMID:24960038

  9. [Possible Instrument Contamination in the Operating Room During Implantation of Knee and Hip Arthroplasty].

    PubMed

    Quint, U; Benen, T

    2016-04-01

    Integrated ventilation systems with low turbulence displacement flow (TAV) are generally legally required in the architectural structure of operating theatres. However, it seems that the instruments laid out on sterile covered tables do not have the best possible protection from bacteria. Within an operating theatre, different bacteria counts are possible on the instruments. This prospective controlled study was conducted to demonstrate the influence of instrument tables with integrated horizontal flow on contamination with pathogens in comparison with conventional tables. In an operating theatre (OT) with a ceiling legally appropriate for TAV (2.40 m × 1.20 m), microbiological samples were placed on a table with integrated TAV flow (n = 100) and on a conventional instrument table (n = 100). The routine qualification of the OT was on an ongoing basis and was in accordance with DIN 1946-4: 1999 standards (in accordance with DIN measurement of recovery time 1946-4: 12-2008). This corresponds to the OT of the room class Ib. The results show significant differences between the two tables. The bacteria count and the percentage of contamination were many times higher on the conventional table. It is important to understand that the instruments are not completely protected against contamination after opening the pack and during the operation. Remedial measures are possible to optimise the sterility the instrument table. PMID:26844853

  10. The Early Years of Practice: An Assessment of Operative Efficiency and Cost of Free Flap and Implant Breast Reconstruction at an Academic Institution.

    PubMed

    Sando, Ian C; Momoh, Adeyiza O; Chung, Kevin C; Kozlow, Jeffrey H

    2016-07-01

    Objective The purpose of this study was to evaluate the short-term costs, and financial implications of improvements in operative efficiency of free flap and implant-based breast reconstruction within an academic practice. Methods The billing records of 162 patients who underwent postmastectomy implant-based or free flap breast reconstruction by two newly hired microsurgeons at an academic institution during the 2011, 2012, and 2013 fiscal years were reviewed. Actual data on professional revenue, relative value units (RVUs), and facility costs for the first stage of reconstruction as well as costs of postoperative complications were assessed. Results Free flaps consistently generated more revenue and RVUs than implants (p < 0.001). Rates of major complications and associated costs were greater for free flaps during the first 2 years of practice; however, by the 3rd year rates were similar between free flaps and implants (14.3 vs. 18.2%, p = 0.72). There was a 26% reduction in free flap operative time in 2013 as compared with 2011. Operative efficiency (hourly RVU) of first stage procedures increased each year for both modalities. At the completion of reconstruction, flaps and implants had comparable hourly reimbursement ($1,053 vs. $947, p = 0.72) and hourly RVU (22 vs. 29, p = 0.06). Conclusions Contrary to perceptions that free flap breast reconstructions are financially inefficient for the surgeon, we have found that these complex reconstructive procedures are profitable. Even in the early years of practice, hourly reimbursements from completed flap reconstructions are similar to reimbursements received from similar staged implant reconstructions. PMID:26872025

  11. Telescopic limiting magnitudes

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.

    1990-01-01

    The prediction of the magnitude of the faintest star visible through a telescope by a visual observer is a difficult problem in physiology. Many prediction formulas have been advanced over the years, but most do not even consider the magnification used. Here, the prediction algorithm problem is attacked with two complimentary approaches: (1) First, a theoretical algorithm was developed based on physiological data for the sensitivity of the eye. This algorithm also accounts for the transmission of the atmosphere and the telescope, the brightness of the sky, the color of the star, the age of the observer, the aperture, and the magnification. (2) Second, 314 observed values for the limiting magnitude were collected as a test of the formula. It is found that the formula does accurately predict the average observed limiting magnitudes under all conditions.

  12. Should Astronomy Abolish Magnitudes?

    NASA Astrophysics Data System (ADS)

    Brecher, K.

    2001-12-01

    Astronomy is riddled with a number of anachronistic and counterintuitive practices. Among these are: plotting increasing stellar temperature from right to left in the H-R diagram; giving the distances to remote astronomical objects in parsecs; and reporting the brightness of astronomical objects in magnitudes. Historical accident and observational technique, respectively, are the bases for the first two practices, and they will undoubtedly persist in the future. However, the use of magnitudes is especially egregious when essentially linear optical detectors like CCDs are used for measuring brightness, which are then reported in a logarithmic (base 2.512 deg!) scale. The use of magnitudes has its origin in three historical artifacts: Ptolemy's method of reporting the brightness of stars in the "Almagest"; the 19th century need for a photographic photometry scale; and the 19th century studies by psychophysicists E. H. Weber and G. T. Fechner on the response of the human eye to light. The latter work sought to uncover the relationship between the subjective response of the human eye and brain to the objective brightness of external optical stimuli. The resulting Fechner-Weber law states that this response is logarithmic: that is, that the eye essentially takes the logarithm of the incoming optical signal. However, after more than a century of perceptual studies, most intensively by S. S. Stevens, it is now well established that this relation is not logarithmic. For naked eye detection of stars from the first to sixth magnitudes, it can be reasonably well fit by a power law with index of about 0.3. Therefore, the modern experimental studies undermine the physiological basis for the use of magnitudes in astronomy. Should the historical origins of magnitudes alone be reason enough for their continued use? Probably not, since astronomical magnitudes are based on outdated studies of human perception; make little sense in an era of linear optical detection; and provide a

  13. Use of broth cultures peri-operatively to optimise the microbiological diagnosis of musculoskeletal implant infections.

    PubMed

    Blackmur, J P; Tang, E Y H; Dave, J; Simpson, A H R W

    2014-11-01

    We compared the use of broth culture medium for samples taken in theatre with the standard practice of placing tissue samples in universal containers. A total of 67 consecutive patients had standard multiple samples of deep tissue harvested at surgery and distributed equally in theatre either to standard universal containers or to broth culture medium. These samples were cultured by direct and enrichment methods. The addition of broth in theatre to standard practice led to an increase in sensitivity from 83% to 95% and an increase in negative predictive value from 77% to 91%. Placing tissue samples directly into broth in the operating theatre is a simple, inexpensive way to increase the sensitivity of cultures from infected patients, and does not appear to compromise the specificity of these cultures. PMID:25371476

  14. The discovery and comparison of symbolic magnitudes.

    PubMed

    Chen, Dawn; Lu, Hongjing; Holyoak, Keith J

    2014-06-01

    Humans and other primates are able to make relative magnitude comparisons, both with perceptual stimuli and with symbolic inputs that convey magnitude information. Although numerous models of magnitude comparison have been proposed, the basic question of how symbolic magnitudes (e.g., size or intelligence of animals) are derived and represented in memory has received little attention. We argue that symbolic magnitudes often will not correspond directly to elementary features of individual concepts. Rather, magnitudes may be formed in working memory based on computations over more basic features stored in long-term memory. We present a model of how magnitudes can be acquired and compared based on BARTlet, a representationally simpler version of Bayesian Analogy with Relational Transformations (BART; Lu, Chen, & Holyoak, 2012). BARTlet operates on distributions of magnitude variables created by applying dimension-specific weights (learned with the aid of empirical priors derived from pre-categorical comparisons) to more primitive features of objects. The resulting magnitude distributions, formed and maintained in working memory, are sensitive to contextual influences such as the range of stimuli and polarity of the question. By incorporating psychological reference points that control the precision of magnitudes in working memory and applying the tools of signal detection theory, BARTlet is able to account for a wide range of empirical phenomena involving magnitude comparisons, including the symbolic distance effect and the semantic congruity effect. We discuss the role of reference points in cognitive and social decision-making, and implications for the evolution of relational representations. PMID:24531498

  15. Landslide seismic magnitude

    NASA Astrophysics Data System (ADS)

    Lin, C. H.; Jan, J. C.; Pu, H. C.; Tu, Y.; Chen, C. C.; Wu, Y. M.

    2015-11-01

    Landslides have become one of the most deadly natural disasters on earth, not only due to a significant increase in extreme climate change caused by global warming, but also rapid economic development in topographic relief areas. How to detect landslides using a real-time system has become an important question for reducing possible landslide impacts on human society. However, traditional detection of landslides, either through direct surveys in the field or remote sensing images obtained via aircraft or satellites, is highly time consuming. Here we analyze very long period seismic signals (20-50 s) generated by large landslides such as Typhoon Morakot, which passed though Taiwan in August 2009. In addition to successfully locating 109 large landslides, we define landslide seismic magnitude based on an empirical formula: Lm = log ⁡ (A) + 0.55 log ⁡ (Δ) + 2.44, where A is the maximum displacement (μm) recorded at one seismic station and Δ is its distance (km) from the landslide. We conclude that both the location and seismic magnitude of large landslides can be rapidly estimated from broadband seismic networks for both academic and applied purposes, similar to earthquake monitoring. We suggest a real-time algorithm be set up for routine monitoring of landslides in places where they pose a frequent threat.

  16. Magnitude correlations in global seismicity

    SciTech Connect

    Sarlis, N. V.

    2011-08-15

    By employing natural time analysis, we analyze the worldwide seismicity and study the existence of correlations between earthquake magnitudes. We find that global seismicity exhibits nontrivial magnitude correlations for earthquake magnitudes greater than M{sub w}6.5.

  17. Prediction of time dependent survival in HF patients after VAD implantation using pre- and post-operative data.

    PubMed

    Kourou, Konstantina; Rigas, George; Exarchos, Konstantinos P; Goletsis, Yorgos; Exarchos, Themis P; Jacobs, Steven; Meyns, Bart; Trivella, Maria-Giovanna; Fotiadis, Dimitrios I

    2016-03-01

    Heart failure is one of the most common diseases worldwide. In recent years, Ventricular Assist Devices (VADs) have become a valuable option for patients with advanced HF. Although it has been shown that VADs improve patient survival rates, several complications persist during left VAD (LVAD) support. The stratification scores currently employed are mostly generic, i.e. not specifically built for LVAD patients, and are based on pre-implantation patient data. In this work we apply data mining approaches for the prediction of time dependent survival in patients after LVAD implantation. Moreover, the predictions acquired with the use of pre-implantation data are enriched by employing post-implantation data, i.e. follow-up data. Different clinical scenarios have been depicted and the subsequent conditions are tested in order to identify the optimal set of pre- and post-implant features, as well as the most suitable algorithms for feature selection and prediction. The proposed approach is applied to a real dataset of 71 patients, reporting an accuracy of 84.5%, sensitivity of 87% and specificity of 82%. Based on the reported results, expert cardio-surgeons can be supported in planning the treatment of VAD patients. PMID:26820445

  18. Cochlear Implants.

    ERIC Educational Resources Information Center

    Clark, Catherine; Scott, Larry

    This brochure explains what a cochlear implant is, lists the types of individuals with deafness who may be helped by a cochlear implant, describes the process of evaluating people for cochlear implants, discusses the surgical process for implanting the aid, traces the path of sound through the cochlear implant to the brain, notes the costs of…

  19. Study of solar wind ions implantation effects in optical coatings in view of Solar Orbiter space mission operation

    NASA Astrophysics Data System (ADS)

    Bacco, D.; Corso, A. J.; Zuppella, P.; Böttger, R.; Gerlin, F.; Napolitani, E.; Tessarolo, E.; Nardello, M.; Pelizzo, M. G.

    2015-09-01

    Low energy ions coming from the quite solar wind are considered among the causes of potential damage of the optical instrumentation and components on board of ESA Solar Orbiter. Predictions of space radiation parameters are available for instruments on board of such mission. Accelerators are commonly used to reproduce the particle irradiation on a spacecraft during its lifetime at the ground level. By selecting energies and equivalent doses it is possible to replicate the damage induced on space components. Implantation of Helium ions has been carried out on different single layer thin films at LEI facility at Forschungszentrum Dresden-Rossendorf varying the total dose. Profile of the implanted samples has been experimentally recovered by SIMS measurements. The change in reflectance performances of such coatings has been experimentally evaluated and modelled. The outcomes have been used to verify the potential impact on the METIS instrument and to drive the optimization of the M0 mirror coating..

  20. Correlation between intra-operative high rate neural response telemetry measurements and behaviourally obtained threshold and comfort levels in patients using Nucleus 24 cochlear implants.

    PubMed

    Mittal, R; Panwar, S S

    2009-06-01

    The correlation between high rate 250 Hz intra-operative threshold neural response telemetry (t-NRT) with behaviourally obtained psychophysical threshold (T) and comfort (C) levels of the most recent and stable maps of 90 consecutive cochlear implantees using Cochlear Implant 24 Mini (CI 24 M) (M: F - 26:19), aged between two and 60 years with a mean age of 9.61 +/-12.07, was studied. The intra-operative t-NRT levels were seen to fall between the T and C levels and a good correlation was found between t-NRT and T and C levels (r = 0.327 at p < 0.005 for the T level and r = 0.648 at p < 0.001 for C level vs intra-operative t-NRT). The present study supports the view that 250 Hz NRT is not only a valuable clinical tool in evaluating the integrity of the implant and status of peripheral auditory nerves but can be used in programming the speech processor for young and difficult recipients, as has been previously shown using low rate NRT. PMID:19025887

  1. Implantable electrical device

    NASA Technical Reports Server (NTRS)

    Jhabvala, M. D. (Inventor)

    1982-01-01

    A fully implantable and self contained device is disclosed composed of a flexible electrode array for surrounding damaged nerves and a signal generator for driving the electrode array with periodic electrical impulses of nanoampere magnitude to induce regeneration of the damaged nerves.

  2. Are all metal-on-metal hip revision operations contributing to the National Joint Registry implant survival curves?

    PubMed Central

    Sabah, S. A.; Henckel, J.; Koutsouris, S.; Rajani, R.; Hothi, H.; Skinner, J. A.; Hart, A. J.

    2016-01-01

    Aims The National Joint Registry for England, Wales and Northern Ireland (NJR) has extended its scope to report on hospital, surgeon and implant performance. Data linkage of the NJR to the London Implant Retrieval Centre (LIRC) has previously evaluated data quality for hip primary procedures, but did not assess revision records. Methods We analysed metal-on-metal hip revision procedures performed between 2003 and 2013. A total of 69 929 revision procedures from the NJR and 929 revised pairs of components from the LIRC were included. Results We were able to link 716 (77.1%) revision procedures on the NJR to the LIRC. This meant that 213 (22.9%) revision procedures at the LIRC could not be identified on the NJR. We found that 349 (37.6%) explants at the LIRC completed the full linkage process to both NJR primary and revision databases. Data completion was excellent (> 99.9%) for revision procedures reported to the NJR. Discussion This study has shown that only approximately one third of retrieved components at the LIRC, contributed to survival curves on the NJR. We recommend prospective registry-retrieval linkage as a tool to feedback missing and erroneous data to the NJR and improve data quality. Take home message: Prospective Registry – retrieval linkage is a simple tool to evaluate and improve data quality on the NJR. Cite this article: Bone Joint J 2016;98-B:33–9. PMID:26733513

  3. Implantable apparatus for localized heating of tissue

    DOEpatents

    Doss, James D.

    1987-01-01

    With the object of repetitively treating deep-seated, inoperable tumors by hyperthermia as well as locally heating other internal tissue masses repetitively, a receiving antenna, transmission line, and electrode arrangment are implanted completely within the patient's body, with the receiving antenna just under the surface of the skin and with the electrode arrangement being located so as to most effectively heat the tissue to be treated. An external, transmitting antenna, driven by an external radio-frequency energy source, is closely coupled to the implanted receiving antenna so that the energy coupled across the air-skin interface provides electromagnetic energy suitable for heating the tissue in the vicinity of the implanted electrodes. The resulting increase in tissue temperature may be estimated by an indirect measurement of the decrease in tissue resistivity in the heated region. This change in resistivity appears as a change in the loading of the receiving antenna which can be measured by either determining the change in the phase relationship between the voltage and the current appearing on the transmitting antenna or by measuring the change in the magnitude of the impedance thereof. Optionally, multiple electrode arrays may be activated or inactivated by the application of magnetic fields to operate implanted magnetic reed switches.

  4. Implantable apparatus for localized heating of tissue

    DOEpatents

    Doss, J.D.

    1985-05-20

    With the object of repetitively treating deep-seated, inoperable tumors by hyperthermia as well as locally heating other internal tissue masses repetitively, a receiving antenna, transmission line and electrode arrangement are implanted completely within the patient's body, with the receiving antenna just under the surface of the skin and with the electrode arrangement being located so as to most effectively heat the tissue to be treated. An external, transmitting antenna, driven by an external radio-frequency energy source, is closely coupled to the implanted receiving antenna so that the energy coupled across the air-skin interface provides electromagnetic energy suitable for heating the tissue in the vicinity of the implanted electrodes. The resulting increase in tissue temperature may be estimated by an indirect measurement of the decrease in tissue resistivity in the heat region. This change in resistivity appears as a change in the loading of the receiving antenna which can be measured by either determining the change in the phase relationship between the voltage and the current appearing on the transmitting antenna or by measuring the change in the magnitude of the impedance thereof. Optionally, multiple electrode arrays may be activated or inactivated by the application of magnetic fields to operate implanted magnetic reed swtiches. 5 figs.

  5. Integrated Circuit Stellar Magnitude Simulator

    ERIC Educational Resources Information Center

    Blackburn, James A.

    1978-01-01

    Describes an electronic circuit which can be used to demonstrate the stellar magnitude scale. Six rectangular light-emitting diodes with independently adjustable duty cycles represent stars of magnitudes 1 through 6. Experimentally verifies the logarithmic response of the eye. (Author/GA)

  6. Statistical models for seismic magnitude

    NASA Astrophysics Data System (ADS)

    Christoffersson, Anders

    1980-02-01

    In this paper some statistical models in connection with seismic magnitude are presented. Two main situations are treated. The first deals with the estimation of magnitude for an event, using a fixed network of stations and taking into account the detection and bias properties of the individual stations. The second treats the problem of estimating seismicity, and detection and bias properties of individual stations. The models are applied to analyze the magnitude bias effects for an earthquake aftershock sequence from Japan, as recorded by a hypothetical network of 15 stations. It is found that network magnitudes computed by the conventional averaging technique are considerably biased, and that a maximum likelihood approach using instantaneous noise-level estimates for non-detecting stations gives the most consistent magnitude estimates. Finally, the models are applied to evaluate the detection characteristics and associated seismicity as recorded by three VELA arrays: UBO (Uinta Basin), TFO (Tonto Forest) and WMO (Wichita Mountains).

  7. Cochlear Implants

    MedlinePlus

    ... electrodes are inserted. The electronic device at the base of the electrode array is then placed under ... FDA approval for implants The Food and Drug Administration (FDA) regulates cochlear implant devices for both adults ...

  8. Goserelin Implant

    MedlinePlus

    Goserelin implant is used in combination with radiation therapy and other medications to treat localized prostate cancer and is ... treatment of abnormal bleeding of the uterus. Goserelin implant is in a class of medications called gonadotropin- ...

  9. Cochlear Implants

    MedlinePlus

    A cochlear implant is a small, complex electronic device that can help to provide a sense of sound. People who are ... of-hearing can get help from them. The implant consists of two parts. One part sits on ...

  10. Carmustine Implant

    MedlinePlus

    Carmustine implant is used along with surgery and sometimes radiation therapy to treat malignant glioma (a certain type of ... Carmustine implant comes as a small wafer that is placed in the brain by a doctor during surgery to ...

  11. Cochlear implant

    MedlinePlus

    ... antenna. This part of the implant receives the sound, converts the sound into an electrical signal, and sends it to ... implants allow deaf people to receive and process sounds and speech. However, these devices do not restore ...

  12. Breast Implants

    MedlinePlus

    ... Updated Safety Information (Consumer Article) FDA Provides Updated Safety Data on Silicone Gel-Filled Breast Implants (Press Announcement) [ARCHIVED] Breast Implant Guidance for Industry (2006) Post Approval Studies Webpage Freedom of Information ...

  13. Backscattering and electron microscopy study of mega-electron volt gold implantation into silicon

    NASA Astrophysics Data System (ADS)

    Alford, T. L.; Theodore, N. David

    1994-12-01

    Rutherford backscattering spectrometry and cross-section transmission electron microscopy have been used to study implantation of MeV Au(+) ions into silicon. Measured range (Rp) and straggle (Delta Rp) values for MeV Au(+) implanted silicon are found to be consistently larger than values predicted by TRIM simulations. The magnitude of the discrepancies are such that the differences cannot be attributed to implantation effects alone. We conclude that the TRIM computer program does not accurately predict Rp and Delta Rp values for MeV Au(+) implantation into crystalline Si. Experimental results show that for low-current low-energy implants a single Gaussian Au profile is achieved. Low-power implants produce a single band of damage consisting of simple point defects. High-current high-energy implants lead to the creation of more complex defect structures such as dislocation networks; these arise as a result of dynamic beam recrystallization. Multiple layers of precipitation are observed in silicon implanted with MeV Au(+) ions in those samples where dynamic recrystallization occurred. Precipitation occurs as a result of the local Au concentration exceeding the solid-solubility during beam-induced recrystallization. Different mechanisms operate in conjunction to cause anomalous Au motion which results in formation of multiple precipitate layers. A first mechanism has the implanted Au segregating into a densely defected region; when the concentration exceeds the local solid solubility Au precipitates out of the matrix. A second mechanism has motion of Au along dislocations in a network; the diffusing Au reaches a dislocation-node where it exceeds the local threshold for precipitation and the Au therefore precipitates. Enhanced Au diffusion is dependent upon the magnitude of dynamic recrystallization occurring during the implantation.

  14. Scaling relations of moment magnitude, local magnitude, and duration magnitude for earthquakes originated in northeast India

    NASA Astrophysics Data System (ADS)

    Bora, Dipok K.

    2016-06-01

    In this study, we aim to improve the scaling between the moment magnitude ( M W), local magnitude ( M L), and the duration magnitude ( M D) for 162 earthquakes in Shillong-Mikir plateau and its adjoining region of northeast India by extending the M W estimates to lower magnitude earthquakes using spectral analysis of P-waves from vertical component seismograms. The M W- M L and M W- M D relationships are determined by linear regression analysis. It is found that, M W values can be considered consistent with M L and M D, within 0.1 and 0.2 magnitude units respectively, in 90 % of the cases. The scaling relationships investigated comply well with similar relationships in other regions in the world and in other seismogenic areas in the northeast India region.

  15. Bidirectional Modulation of Numerical Magnitude.

    PubMed

    Arshad, Qadeer; Nigmatullina, Yuliya; Nigmatullin, Ramil; Asavarut, Paladd; Goga, Usman; Khan, Sarah; Sander, Kaija; Siddiqui, Shuaib; Roberts, R E; Cohen Kadosh, Roi; Bronstein, Adolfo M; Malhotra, Paresh A

    2016-05-01

    Numerical cognition is critical for modern life; however, the precise neural mechanisms underpinning numerical magnitude allocation in humans remain obscure. Based upon previous reports demonstrating the close behavioral and neuro-anatomical relationship between number allocation and spatial attention, we hypothesized that these systems would be subject to similar control mechanisms, namely dynamic interhemispheric competition. We employed a physiological paradigm, combining visual and vestibular stimulation, to induce interhemispheric conflict and subsequent unihemispheric inhibition, as confirmed by transcranial direct current stimulation (tDCS). This allowed us to demonstrate the first systematic bidirectional modulation of numerical magnitude toward either higher or lower numbers, independently of either eye movements or spatial attention mediated biases. We incorporated both our findings and those from the most widely accepted theoretical framework for numerical cognition to present a novel unifying computational model that describes how numerical magnitude allocation is subject to dynamic interhemispheric competition. That is, numerical allocation is continually updated in a contextual manner based upon relative magnitude, with the right hemisphere responsible for smaller magnitudes and the left hemisphere for larger magnitudes. PMID:26879093

  16. Bidirectional Modulation of Numerical Magnitude

    PubMed Central

    Arshad, Qadeer; Nigmatullina, Yuliya; Nigmatullin, Ramil; Asavarut, Paladd; Goga, Usman; Khan, Sarah; Sander, Kaija; Siddiqui, Shuaib; Roberts, R. E.; Cohen Kadosh, Roi; Bronstein, Adolfo M.; Malhotra, Paresh A.

    2016-01-01

    Numerical cognition is critical for modern life; however, the precise neural mechanisms underpinning numerical magnitude allocation in humans remain obscure. Based upon previous reports demonstrating the close behavioral and neuro-anatomical relationship between number allocation and spatial attention, we hypothesized that these systems would be subject to similar control mechanisms, namely dynamic interhemispheric competition. We employed a physiological paradigm, combining visual and vestibular stimulation, to induce interhemispheric conflict and subsequent unihemispheric inhibition, as confirmed by transcranial direct current stimulation (tDCS). This allowed us to demonstrate the first systematic bidirectional modulation of numerical magnitude toward either higher or lower numbers, independently of either eye movements or spatial attention mediated biases. We incorporated both our findings and those from the most widely accepted theoretical framework for numerical cognition to present a novel unifying computational model that describes how numerical magnitude allocation is subject to dynamic interhemispheric competition. That is, numerical allocation is continually updated in a contextual manner based upon relative magnitude, with the right hemisphere responsible for smaller magnitudes and the left hemisphere for larger magnitudes. PMID:26879093

  17. Multi-catheter interstitial brachytherapy for partial breast irradiation: an audit of implant quality based on dosimetric evaluation comparing intra-operative versus post-operative placement

    PubMed Central

    Gurram, Lavanya; Joshi, Kishor; Phurailatpam, Reena; Paul, Siji; Sarin, Rajiv

    2016-01-01

    Purpose The use of multicatheter interstitial brachytherapy (MIB) for accelerated partial breast irradiation (APBI) in early breast cancer (EBC) patients outside the trial setting has increased. Hence, there is a need to critically evaluate implant quality. Moreover, there is a scarcity of reports using an open cavity technique. We report the dosimetric indices of open and closed cavity MIB techniques. Material and methods The dosimetric parameters of 60 EBC patients treated with MIB (open and closed cavity) who underwent three dimensional, computerized tomography (CT) based planning for APBI from November 2011 to July 2015 were evaluated. Coverage Index (CI), Dose Homogeneity Index (DHI), Conformity Index (COIN), Plan Quality Index (PQI), and Dose Non-uniformity Index (DNR) were assessed. Results Forty-one patients underwent open cavity and 19 patients underwent closed cavity placement of brachytherapy catheters. The median number of planes was 4 and median number of needles was 20. Median dose was 34 Gy with dose per fraction of 3.4 Gy, given twice a day, 6 hours apart. The D90 of the cavity and clinical target volume (CTV) were 105% and 89%, respectively. The median doses to the surgical clips were greater than 100%. The median CI of the cavity and CTV was 0.96 and 0.82, respectively. The DHI and COIN index of the CTV was 0.73 and 0.67. There were no significant differences in the dosimetric parameters based on whether the technique was done open or closed. Conclusions Critical evaluation of the dosimetric parameters of MIB-APBI is important for optimal results. While the open and closed techniques have similar dosimetry, our institutional preference is for an open technique which eases the procedure due to direct visualization of the tumor cavity. PMID:27257415

  18. Implantable Microimagers

    PubMed Central

    Ng, David C.; Tokuda, Takashi; Shiosaka, Sadao; Tano, Yasuo; Ohta, Jun

    2008-01-01

    Implantable devices such as cardiac pacemakers, drug-delivery systems, and defibrillators have had a tremendous impact on the quality of live for many disabled people. To date, many devices have been developed for implantation into various parts of the human body. In this paper, we focus on devices implanted in the head. In particular, we describe the technologies necessary to create implantable microimagers. Design, fabrication, and implementation issues are discussed vis-à-vis two examples of implantable microimagers; the retinal prosthesis and in vivo neuro-microimager. Testing of these devices in animals verify the use of the microimagers in the implanted state. We believe that further advancement of these devices will lead to the development of a new method for medical and scientific applications.

  19. High Productivity Implantation ''PARTIAL IMPLANT''

    SciTech Connect

    Hino, Masayoshi; Miyamoto, Naoki; Sakai, Shigeki; Matsumoto, Takao

    2008-11-03

    The patterned ion implantation 'PARTIAL IMPLANT' has been developed as a productivity improvement tool. The Partial Implant can form several different ion dose areas on the wafer surface by controlling the speed of wafer moving and the stepwise rotation of twist axis. The Partial Implant system contains two implant methods. One method is 'DIVIDE PARTIAL IMPLANT', that is aimed at reducing the consumption of the wafer. The Divide Partial Implant evenly divides dose area on one wafer surface into two or three different dose part. Any dose can be selected in each area. So the consumption of the wafer for experimental implantation can be reduced. The second method is 'RING PARTIAL IMPLANT' that is aimed at improving yield by correcting electrical characteristic of devices. The Ring Partial Implant can form concentric ion dose areas. The dose of wafer external area can be selected to be within plus or minus 30% of dose of wafer central area. So the electrical characteristic of devices can be corrected by controlling dose at edge side on the wafer.

  20. Understanding Magnitudes to Understand Fractions

    ERIC Educational Resources Information Center

    Gabriel, Florence

    2016-01-01

    Fractions are known to be difficult to learn and difficult to teach, yet they are vital for students to have access to further mathematical concepts. This article uses evidence to support teachers employing teaching methods that focus on the conceptual understanding of the magnitude of fractions.

  1. Enhancement mode operation in AlInN/GaN (MIS)HEMTs on Si substrates using a fluorine implant

    NASA Astrophysics Data System (ADS)

    Zaidi, Z. H.; Lee, K. B.; Guiney, I.; Qian, H.; Jiang, S.; Wallis, D. J.; Humphreys, C. J.; Houston, P. A.

    2015-10-01

    We have demonstrated enhancement mode operation of AlInN/GaN (MIS)HEMTs on Si substrates using the fluorine treatment technique. The plasma RF power and treatment time was optimized to prevent the penetration of the fluorine into the channel region to maintain high channel conductivity and transconductance. An analysis of the threshold voltage was carried out which defined the requirement for the fluorine sheet concentration to exceed the charge at the dielectric/AlInN interface to achieve an increase in the positive threshold voltage after deposition of the dielectric. This illustrates the importance of control of both the plasma conditions and the interfacial charge for a reproducible threshold voltage. A positive threshold voltage of +3 V was achieved with a maximum drain current of 367 mA mm-1 at a forward gate bias of 10 V.

  2. [Implant allergies].

    PubMed

    Thomas, P; Thomsen, M

    2010-03-01

    An increasing number of patients receive and benefit from osteosynthesis materials or artificial joint replacement. The most common complications are mechanical problems or infection. Metals like nickel, chromium and cobalt as well as bone cement components like acrylates and gentamicin are potential contact allergens which can cause intolerance reactions to implants. Eczema, delayed wound/bone healing, recurrent effusions, pain and implant loosening all have been described as manifestation of implant allergy. In contrast to the high incidence of cutaneous metal allergy, allergies associated with implants are rare. Diagnosis of metal implant allergy is still difficult. Thus differential diagnoses--in particular infection--have to be excluded and a combined approach of allergologic diagnostics by patch test and histopathology of peri-implant tissue is recommended. It is still unknown which conditions induce allergic sensitization to implants or trigger peri-implant allergic reactions in the case of preexisting cutaneous metal allergy. Despite the risk of developing complications being unclear, titanium based osteosynthesis materials are recommended for metal allergic patients and the use of metal-metal couplings in arthroplasty is not recommended for such patients. If the regular CoCr-polyethylene articulation is employed, the patient should give informed written consent. PMID:20204719

  3. Imaging for cochlear implants.

    PubMed

    Phelps, P D; Annis, J A; Robinson, P J

    1990-07-01

    Insertion of a sound amplification device into the round window niche (extracochlear implant) or into the coils of the cochlea (intracochlear implant) can give significant benefits to some carefully selected, severely deaf patients. Imaging has an essential role in selective and pre-operative assessment. Severe otosclerosis and post-meningitic labyrinthitis ossificans are common causes of deafness in these patients and can be demonstrated by computed tomography (CT). The most suitable side for operation can be assessed. We describe our experiences with 165 patients, 69 of whom were found suitable for implants. Thin (1 mm) section CT in axial and coronal planes is the best imaging investigation of the petrous temporal bones but the place of magnetic resonance scanning to confirm that the inner ear is fluid-filled and polytomography to show a multichannel implant in the cochlea is discussed. No implants were used for congenital deformities, but some observations are made of this type of structural deformity of the inner ear. PMID:2390686

  4. The representation of numerical magnitude

    PubMed Central

    Brannon, Elizabeth M

    2006-01-01

    The combined efforts of many fields are advancing our understanding of how number is represented. Researchers studying numerical reasoning in adult humans, developing humans and non-human animals are using a suite of behavioral and neurobiological methods to uncover similarities and differences in how each population enumerates and compares quantities to identify the neural substrates of numerical cognition. An important picture emerging from this research is that adult humans share with non-human animals a system for representing number as language-independent mental magnitudes and that this system emerges early in development. PMID:16546373

  5. Remote actuated valve implant

    DOEpatents

    McKnight, Timothy E; Johnson, Anthony; Moise, Jr., Kenneth J; Ericson, Milton Nance; Baba, Justin S; Wilgen, John B; Evans, III, Boyd McCutchen

    2014-02-25

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  6. Remote actuated valve implant

    DOEpatents

    McKnight, Timothy E.; Johnson, Anthony; Moise, Kenneth J.; Ericson, Milton Nance; Baba, Justin S.; Wilgen, John B.; Evans, Boyd Mccutchen

    2016-05-10

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  7. Orientation and Magnitude of Mars' Magnetic Field

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image shows the orientation and magnitude of the magnetic field measured by the MGS magnetometer as it sped over the surface of Mars during an early aerobraking pass (Day of the year, 264; 'P6' periapsis pass). At each point along the spacecraft trajectory we've drawn vectors in the direction of the magnetic field measured at that instant; the length of the line is scaled to show the relative magnitude of the field. Imagine traveling along with the MGS spacecraft, holding a string with a magnetized needle on one end: this essentially a compass with a needle that is free to spin in all directions. As you pass over the surface the needle would swing rapidly, first pointing towards the planet and then rotating quickly towards 'up' and back down again. All in a relatively short span of time, say a minute or two, during which time the spacecraft has traveled a couple of hundred miles. You've just passed over one of many 'magnetic anomalies' thus far detected near the surface of Mars. A second major anomaly appears a little later along the spacecraft track, about 1/4 the magnitude of the first - can you find it? The short scale length of the magnetic field signature locates the source near the surface of Mars, perhaps in the crust, a 10 to 75 kilometer thick outer shell of the planet (radius 3397 km).

    The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. JPL is an operating division of California Institute of Technology (Caltech).

  8. Implants for draining neovascular glaucoma.

    PubMed Central

    Molteno, A C; Van Rooyen, M M; Bartholomew, R S

    1977-01-01

    The implant design, surgical technique, and pharmacological methods of controlling bleb fibrosis, used to treat neovascular glaucoma, are described, together with the results of 14 operations performed on 12 eyes. Images PMID:843508

  9. Cochlear Implants

    MedlinePlus

    ... additional visits are needed for activating, adjusting, and programming the various electrodes that have been implanted. Also, ... to the center for checkups once the final programming is made to the speech processor. Both children ...

  10. Histrelin Implant

    MedlinePlus

    ... bone growth and development of sexual characteristics) in girls usually between 2 and 8 years of age ... MRI scans (radiology techniques designed to show the images of body structures) to find the implant when ...

  11. Goserelin Implant

    MedlinePlus

    ... which the type of tissue that lines the uterus [womb] grows in other areas of the body ... with the treatment of abnormal bleeding of the uterus. Goserelin implant is in a class of medications ...

  12. Ion Implantation

    NASA Astrophysics Data System (ADS)

    Langouche, G.; Yoshida, Y.

    In this tutorial we describe the basic principles of the ion implantation technique and we demonstrate that emission Mössbauer spectroscopy is an extremely powerful technique to investigate the atomic and electronic configuration around implanted atoms. The physics of dilute atoms in materials, the final lattice sites and their chemical state as well as diffusion phenomena can be studied. We focus on the latest developments of implantation Mössbauer spectroscopy, where three accelerator facilities, i.e., Hahn-Meitner Institute Berlin, ISOLDE-CERN and RIKEN, have intensively been used for materials research in in-beam and on-line Mössbauer experiments immediately after implantation of the nuclear probes.

  13. Dental Implants

    MedlinePlus Videos and Cool Tools

    ... facts so you can make an informed decision as to whether dental implants are right for your ... the jaw bone. It’s obviously not the same as the original connection , but functions just the same. ...

  14. Solar Variability Magnitudes and Timescales

    NASA Astrophysics Data System (ADS)

    Kopp, Greg

    2015-08-01

    The Sun’s net radiative output varies on timescales of minutes to many millennia. The former are directly observed as part of the on-going 37-year long total solar irradiance climate data record, while the latter are inferred from solar proxy and stellar evolution models. Since the Sun provides nearly all the energy driving the Earth’s climate system, changes in the sunlight reaching our planet can have - and have had - significant impacts on life and civilizations.Total solar irradiance has been measured from space since 1978 by a series of overlapping instruments. These have shown changes in the spatially- and spectrally-integrated radiant energy at the top of the Earth’s atmosphere from timescales as short as minutes to as long as a solar cycle. The Sun’s ~0.01% variations over a few minutes are caused by the superposition of convection and oscillations, and even occasionally by a large flare. Over days to weeks, changing surface activity affects solar brightness at the ~0.1% level. The 11-year solar cycle has comparable irradiance variations with peaks near solar maxima.Secular variations are harder to discern, being limited by instrument stability and the relatively short duration of the space-borne record. Proxy models of the Sun based on cosmogenic isotope records and inferred from Earth climate signatures indicate solar brightness changes over decades to millennia, although the magnitude of these variations depends on many assumptions. Stellar evolution affects yet longer timescales and is responsible for the greatest solar variabilities.In this talk I will summarize the Sun’s variability magnitudes over different temporal ranges, showing examples relevant for climate studies as well as detections of exo-solar planets transiting Sun-like stars.

  15. Operations

    ERIC Educational Resources Information Center

    Wilkins, Jesse L. M.; Norton, Anderson; Boyce, Steven J.

    2013-01-01

    Previous research has documented schemes and operations that undergird students' understanding of fractions. This prior research was based, in large part, on small-group teaching experiments. However, written assessments are needed in order for teachers and researchers to assess students' ways of operating on a whole-class scale. In this…

  16. PRE-OPERATIVE PLANNING AND SURGICAL TECHNIQUE OF THE OPEN WEDGE SUPRACONDYLAR OSTEOTOMY FOR CORRECTION OF VALGUS KNEE AND FIXATION WITH A FIXED-ANGLE IMPLANT

    PubMed Central

    Paccola, Cleber Antonio Jansen

    2015-01-01

    The step-by-step preoperative planning for supracondylar opening wedge osteotomy of the femur for precise correction of the load axis of the lower limb using a fixed-angle implant (95° AO blade plate) is presented. The surgical technique and the use of a bone graft from the same site for filling in the defect are also presented. PMID:27026976

  17. Cochlear Implants

    MedlinePlus

    ... outside of the body, behind the ear. A second part is surgically placed under the skin. An implant does not restore normal hearing. It can help a person understand speech. Children and adults can benefit from them. National Institute on Deafness and Other Communication Disorders

  18. Cochlear implant

    MedlinePlus

    ... are sent along the auditory nerve to the brain. A deaf person does not have a functioning inner ear. A cochlear implant tries to replace the function of the inner ear by ... signals to the brain. Sound is picked up by a microphone worn ...

  19. Astronomical Limiting Magnitude at Langkawi Observatory

    NASA Astrophysics Data System (ADS)

    Zainuddin, Mohd. Zambri; Loon, Chin Wei; Harun, Saedah

    2010-07-01

    Astronomical limiting magnitude is an indicator for astronomer to conduct astronomical measurement at a particular site. It gives an idea to astronomer of that site what magnitude of celestial object can be measured. Langkawi National Observatory (LNO) is situated at Bukit Malut with latitude 6°18' 25'' North and longitude 99°46' 52'' East in Langkawi Island. Sky brightness measurement has been performed at this site using the standard astronomical technique. The value of the limiting magnitude measured is V = 18.6+/-1.0 magnitude. This will indicate that astronomical measurement at Langkawi observatory can only be done for celestial objects having magnitude less than V = 18.6 magnitudes.

  20. A scheme to set preferred magnitudes in the ISC Bulletin

    NASA Astrophysics Data System (ADS)

    Di Giacomo, Domenico; Storchak, Dmitry A.

    2016-04-01

    One of the main purposes of the International Seismological Centre (ISC) is to collect, integrate and reprocess seismic bulletins provided by agencies around the world in order to produce the ISC Bulletin. This is regarded as the most comprehensive bulletin of the Earth's seismicity, and its production is based on a unique cooperation in the seismological community that allows the ISC to complement the work of seismological agencies operating at global and/or local-regional scale. In addition, by using the seismic wave measurements provided by reporting agencies, the ISC computes, where possible, its own event locations and magnitudes such as short-period body wave m b and surface wave M S . Therefore, the ISC Bulletin contains the results of the reporting agencies as well as the ISC own solutions. Among the most used seismic event parameters listed in seismological bulletins, the event magnitude is of particular importance for characterizing a seismic event. The selection of a magnitude value (or multiple ones) for various research purposes or practical applications is not always a straightforward task for users of the ISC Bulletin and related products since a multitude of magnitude types is currently computed by seismological agencies (sometimes using different standards for the same magnitude type). Here, we describe a scheme that we intend to implement in routine ISC operations to mark the preferred magnitudes in order to help ISC users in the selection of events with magnitudes of their interest.

  1. [Maintenance care for dental implant].

    PubMed

    Kamoi, K

    1989-10-01

    with patient himself. Ultimate concept of implantology have supported common concordance with periodontal therapy. 2) Patients consent and co-operation the right of informed consent, agreement to treatment by the patient has been gaining increased importance to implantology. Even the patient has consent, they must co-operate the process of dental implant with co-therapist (Fig. 2). 3) The clinical examination of clinical parameters in dental implants. (1) Plaque Index (Silness & Loe 1964) and Plaque Control Record (0 Leary 1978) (Table 5). (2) Gingival inflammation (Fig. 3). Ordinarlly, Gingival Bleeding Index (GBI Ainamo & Bay 1975) and Papilla Bleeding Index (Saxer & Jühlemann 1975) are used. (3) The depth of peri-implant sulcus with the plastic probe. (NDU style) (Fig. 4).(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2489287

  2. Cochlear Implantation in Neurobrucellosis

    PubMed Central

    Bajin, Münir Demir; Savaş, Özden; Aslan, Filiz; Sennaroğlu, Levent

    2016-01-01

    Background: Neurobrucellosis is a disease consisting of a wide spectrum of complications such as peripheral neuropathy, cranial nerve involvement, ataxia, meningeal irritation, paraplegia, seizures, coma, and even death. The vestibulocochlear nerve seems to be the most commonly affected cranial nerve (10%). We present a patient with neurobrucellosis whose auditory perception and speech intelligibility skill performances improved after cochlear implantation. Case Report: A 35 year-old woman was admitted to another hospital 2 years ago with the symptoms of headache, nausea, and altered consciousness, who was finally diagnosed with neurobrucellosis. She developed bilateral profound sensorineural hearing loss during the following 6 months. There was no benefit of using hearing aids. After successful treatment of her illness, she was found to be suitable for cochlear implantation. After the operation, her auditory perception skills improved significantly with a Categories of Auditory Performance (CAP) score of 5. According to clinical observations and her family members’ statements, her Speech Intelligibility Rating (SIR) score was 3. Her speech intelligibility skills are still improving. Conclusion: Our case report represents the second case of hearing rehabilitation with cochlear implantation after neurobrucellosis. Cochlear implantation is a cost-effective and time-proven successful intervention in post-lingual adult patients with sensorineural hearing loss. Early timing of the surgery after appropriate treatment of meningitis helps the patient to achieve better postoperative results. PMID:26966626

  3. Magnitude correlations and dynamical scaling for seismicity

    SciTech Connect

    Godano, Cataldo; Lippiello, Eugenio; De Arcangelis, Lucilla

    2007-12-06

    We analyze the experimental seismic catalog of Southern California and we show the existence of correlations between earthquake magnitudes. We propose a dynamical scaling hypothesis relating time and magnitude as the physical mechanism responsible of the observed magnitude correlations. We show that experimental distributions in size and time naturally originate solely from this scaling hypothesis. Furthermore we generate a synthetic catalog reproducing the organization in time and magnitude of experimental data.

  4. An unusual case of a ruptured Poly Implant Prothèse breast implant associated with xanthoma

    PubMed Central

    Dinets, Andrii; Unukovych, Dmytro; Khrapach, Vasyl; Zakhartseva, Olga; Sulik, Volodymyr; Kaminskyi, Edgar; Khrapach, Olexandr; Meloyan, Ani; Zakhartseva, Lubov; Mishalov, Volodymyr

    2016-01-01

    Abstract A suspicious breast mass was intra-operatively found in a female patient previously operated for breast augmentation with the Poly Implant Prothèse (PIP) implants. The neoplasm was verified as xanthoma and an asymptomatic microrupture of PIP was also detected. This report discusses possible association of breast xanthoma with PIP implant rupture.

  5. An unusual case of a ruptured Poly Implant Prothèse breast implant associated with xanthoma.

    PubMed

    Dinets, Andrii; Unukovych, Dmytro; Khrapach, Vasyl; Zakhartseva, Olga; Sulik, Volodymyr; Kaminskyi, Edgar; Khrapach, Olexandr; Meloyan, Ani; Zakhartseva, Lubov; Mishalov, Volodymyr

    2016-01-01

    A suspicious breast mass was intra-operatively found in a female patient previously operated for breast augmentation with the Poly Implant Prothèse (PIP) implants. The neoplasm was verified as xanthoma and an asymptomatic microrupture of PIP was also detected. This report discusses possible association of breast xanthoma with PIP implant rupture. PMID:27583262

  6. Reinforcer Magnitude Attenuates Apomorphine's Effects on Operant Pecking

    ERIC Educational Resources Information Center

    Pinkston, Jonathan W.; Lamb, R. J.

    2012-01-01

    When given to pigeons, the direct-acting dopamine agonist apomorphine elicits pecking. The response has been likened to foraging pecking because it bears remarkable similarity to foraging behavior, and it is enhanced by food deprivation. On the other hand, other data suggest the response is not related to foraging behavior and may even interfere…

  7. Magnitude and sign correlations in heartbeat fluctuations

    NASA Technical Reports Server (NTRS)

    Ashkenazy, Y.; Ivanov, P. C.; Havlin, S.; Peng, C. K.; Goldberger, A. L.; Stanley, H. E.

    2001-01-01

    We propose an approach for analyzing signals with long-range correlations by decomposing the signal increment series into magnitude and sign series and analyzing their scaling properties. We show that signals with identical long-range correlations can exhibit different time organization for the magnitude and sign. We find that the magnitude series relates to the nonlinear properties of the original time series, while the sign series relates to the linear properties. We apply our approach to the heartbeat interval series and find that the magnitude series is long-range correlated, while the sign series is anticorrelated and that both magnitude and sign series may have clinical applications.

  8. Magnitude systems in old star catalogues

    NASA Astrophysics Data System (ADS)

    Fujiwara, Tomoko; Yamaoka, Hitoshi

    2005-06-01

    The current system of stellar magnitudes originally introduced by Hipparchus was strictly defined by Norman Pogson in 1856. He based his system on Ptolemy's star catalogue, the Almagest, recorded in about AD137, and defined the magnitude-intensity relationship on a logarithmic scale. Stellar magnitudes observed with the naked eye recorded in seven old star catalogues were analyzed in order to examine the visual magnitude systems. Although psychophysicists have proposed that human visual sensitivity follows a power-law scale, it is shown here that the degree of agreement is far better for a logarithmic scale than for a power-law scale. It is also found that light ratios in each star catalogue are nearly equal to 2.512, if the brightest (1st magnitude) and the faintest (6th magnitude and dimmer) stars are excluded from the study. This means that the visual magnitudes in the old star catalogues agree fully with Pogson's logarithmic scale.

  9. Advances in lens implant technology

    PubMed Central

    Kampik, Anselm; Dexl, Alois K.; Zimmermann, Nicole; Glasser, Adrian; Baumeister, Martin; Kohnen, Thomas

    2013-01-01

    Cataract surgery is one of the oldest and the most frequent outpatient clinic operations in medicine performed worldwide. The clouded human crystalline lens is replaced by an artificial intraocular lens implanted into the capsular bag. During the last six decades, cataract surgery has undergone rapid development from a traumatic, manual surgical procedure with implantation of a simple lens to a minimally invasive intervention increasingly assisted by high technology and a broad variety of implants customized for each patient’s individual requirements. This review discusses the major advances in this field and focuses on the main challenge remaining – the treatment of presbyopia. The demand for correction of presbyopia is increasing, reflecting the global growth of the ageing population. Pearls and pitfalls of currently applied methods to correct presbyopia and different approaches under investigation, both in lens implant technology and in surgical technology, are discussed. PMID:23413369

  10. Microsystems Technology for Retinal Implants

    NASA Astrophysics Data System (ADS)

    Weiland, James

    2005-03-01

    The retinal prosthesis is targeted to treat age-related macular degeneration, retinitis pigmentosa, and other outer retinal degenerations. Simulations of artificial vision have predicted that 600-1000 individual pixels will be needed if a retinal prosthesis is to restore function such as reading large print and face recognition. An implantable device with this many electrode contacts will require microsystems technology as part of its design. An implantable retinal prosthesis will consist of several subsystems including an electrode array and hermetic packaging. Microsystems and microtechnology approaches are being investigated as possible solutions for these design problems. Flexible polydimethylsiloxane (PDMS) substrate electrode arrays and silicon micromachined electrode arrays are under development. Inactive PDMS electrodes have been implanted in 3 dogs to assess mechanical biocompatibility. 3 dogs were followed for 6 months. The implanted was securely fastened to the retina with a single retinal tack. No post-operative complications were evident. The array remained within 100 microns of the retinal surface. Histological evaluation showed a well preserved retina underneath the electrode array. A silicon device with electrodes suspended on micromachined springs has been implanted in 4 dogs (2 acute implants, 2 chronic implants). The device, though large, could be inserted into the eye and positioned on the retina. Histological analysis of the retina from the spring electrode implants showed that spring mounted posts penetrated the retina, thus the device will be redesigned to reduce the strength of the springs. These initial implants will provide information for the designers to make the next generation silicon device. We conclude that microsystems technology has the potential to make possible a retinal prosthesis with 1000 individual contacts in close proximity to the retina.

  11. Sterilisation of implantable devices.

    PubMed

    Matthews, I P; Gibson, C; Samuel, A H

    1994-01-01

    The pathogenesis and rates of infection associated with the use of a wide variety of implantable devices are described. The multi-factorial nature of post-operative periprosthetic infection is outlined and the role of sterilisation of devices is explained. The resistance of bacterial spores is highlighted as a problem and a full description is given of the processes of sterilisation by heat, steam, ethylene oxide, low temperature steam and formaldehyde, ionising radiation and liquid glutaraldehyde. Sterility assurance and validation are discussed in the context of biological indicators and physical/chemical indicators. Adverse effects upon the material composition of devices and problems of process control are listed. Finally, possible optimisations of the ethylene oxide process and their potential significance to the field of sterilisation of implants is explored. PMID:10172076

  12. Absolute magnitudes of trans-neptunian objects

    NASA Astrophysics Data System (ADS)

    Duffard, R.; Alvarez-candal, A.; Pinilla-Alonso, N.; Ortiz, J. L.; Morales, N.; Santos-Sanz, P.; Thirouin, A.

    2015-10-01

    Accurate measurements of diameters of trans- Neptunian objects are extremely complicated to obtain. Radiomatric techniques applied to thermal measurements can provide good results, but precise absolute magnitudes are needed to constrain diameters and albedos. Our objective is to measure accurate absolute magnitudes for a sample of trans- Neptunian objects, many of which have been observed, and modelled, by the "TNOs are cool" team, one of Herschel Space Observatory key projects grantes with ~ 400 hours of observing time. We observed 56 objects in filters V and R, if possible. These data, along with data available in the literature, was used to obtain phase curves and to measure absolute magnitudes by assuming a linear trend of the phase curves and considering magnitude variability due to rotational light-curve. In total we obtained 234 new magnitudes for the 56 objects, 6 of them with no reported previous measurements. Including the data from the literature we report a total of 109 absolute magnitudes.

  13. Estimating magnitude and duration of incident delays

    SciTech Connect

    Garib, A.; Radwan, A.E.; Al-Deek, H.

    1997-11-01

    Traffic congestion is a major operational problem on urban freeways. In the case of recurring congestion, travelers can plan their trips according to the expected occurrence and severity of recurring congestion. However, nonrecurring congestion cannot be managed without real-time prediction. Evaluating the efficiency of intelligent transportation systems (ITS) technologies in reducing incident effects requires developing models that can accurately predict incident duration along with the magnitude of nonrecurring congestion. This paper provides two statistical models for estimating incident delay and a model for predicting incident duration. The incident delay models showed that up to 85% of variation in incident delay can be explained by incident duration, number of lanes affected, number of vehicles involved, and traffic demand before the incident. The incident duration prediction model showed that 81% of variation in incident duration can be predicted by number of lanes affected, number of vehicles involved, truck involvement, time of day, police response time, and weather condition. These findings have implications for on-line applications within the context of advanced traveler information systems (ATIS).

  14. CO2 laser surface treatment of failed dental implants for re-implantation: an animal study.

    PubMed

    Kasraei, Shahin; Torkzaban, Parviz; Shams, Bahar; Hosseinipanah, Seyed Mohammad; Farhadian, Maryam

    2016-07-01

    The aim of the present study was to evaluate the success rate of failed implants re-implanted after surface treatment with CO2 laser. Despite the widespread use of dental implants, there are many incidents of failures. It is believed that lasers can be applied to decontaminate the implant surface without damaging the implant. Ten dental implants that had failed for various reasons other than fracture or surface abrasion were subjected to CO2 laser surface treatment and randomly placed in the maxillae of dogs. Three failed implants were also placed as the negative controls after irrigation with saline solution without laser surface treatment. The stability of the implants was evaluated by the use of the Periotest values (PTVs) on the first day after surgery and at 1, 3, and 6 months post-operatively. The mean PTVs of treated implants increased at the first month interval, indicating a decrease in implant stability due to inflammation followed by healing of the tissue. At 3 and 6 months, the mean PTVs decreased compared to the 1-month interval (P < 0.05), indicating improved implant stability. The mean PTVs increased in the negative control group compared to baseline (P < 0.05). Independent t-test showed that the mean PTVs of treated implants were significantly lower than control group at 3 and 6 months after implant placement (P < 0.05). Based on the PTVs, re-implantation of failed implants in Jack Russell Terrier dogs after CO2 laser surface debridement is associated with a high success rate in terms of implant stability. PMID:27126410

  15. Wireless power transfer to a cardiac implant

    NASA Astrophysics Data System (ADS)

    Kim, Sanghoek; Ho, John S.; Chen, Lisa Y.; Poon, Ada S. Y.

    2012-08-01

    We analyze wireless power transfer between a source and a weakly coupled implant on the heart. Numerical studies show that mid-field wireless powering achieves much higher power transfer efficiency than traditional inductively coupled systems. With proper system design, power sufficient to operate typical cardiac implants can be received by millimeter-sized coils.

  16. A Novel Operative Procedure for Pelvic Organ Prolapse Utilizing a MRI-Visible Mesh Implant: Safety and Outcome of Modified Laparoscopic Bilateral Sacropexy

    PubMed Central

    Meyberg-Solomayer, Gabriele; Radosa, Julia; Bader, Werner; Schneider, Guenther; Solomayer, Erich

    2015-01-01

    Introduction. Sacropexy is a generally applied treatment of prolapse, yet there are known possible complications of it. An essential need exists for better alloplastic materials. Methods. Between April 2013 and June 2014, we performed a modified laparoscopic bilateral sacropexy (MLBS) in 10 patients using a MRI-visible PVDF mesh implant. Selected patients had prolapse POP-Q stages II-III and concomitant OAB. We studied surgery-related morbidity, anatomical and functional outcome, and mesh-visibility in MRI. Mean follow-up was 7.4 months. Results. Concomitant colporrhaphy was conducted in 1/10 patients. Anatomical success was defined as POP-Q stage 0-I. Apical success rate was 100% and remained stable. A recurrent cystocele was seen in 1/10 patients during follow-up without need for intervention. Out of 6 (6/10) patients with preoperative SUI, 5/6 were healed and 1/6 persisted. De-novo SUI was seen in 1/10 patients. Complications requiring a relaparoscopy were seen in 2/10 patients. 8/10 patients with OAB were relieved postoperatively. The first in-human magnetic resonance visualization of a prolapse mesh implant was performed and showed good quality of visualization. Conclusion. MLBS is a feasible and safe procedure with favorable anatomical and functional outcome and good concomitant healing rates of SUI and OAB. Prospective data and larger samples are required. PMID:25961042

  17. Ion implanted dielectric elastomer circuits

    NASA Astrophysics Data System (ADS)

    O'Brien, Benjamin M.; Rosset, Samuel; Anderson, Iain A.; Shea, Herbert R.

    2013-06-01

    Starfish and octopuses control their infinite degree-of-freedom arms with panache—capabilities typical of nature where the distribution of reflex-like intelligence throughout soft muscular networks greatly outperforms anything hard, heavy, and man-made. Dielectric elastomer actuators show great promise for soft artificial muscle networks. One way to make them smart is with piezo-resistive Dielectric Elastomer Switches (DES) that can be combined with artificial muscles to create arbitrary digital logic circuits. Unfortunately there are currently no reliable materials or fabrication process. Thus devices typically fail within a few thousand cycles. As a first step in the search for better materials we present a preliminary exploration of piezo-resistors made with filtered cathodic vacuum arc metal ion implantation. DES were formed on polydimethylsiloxane silicone membranes out of ion implanted gold nano-clusters. We propose that there are four distinct regimes (high dose, above percolation, on percolation, low dose) in which gold ion implanted piezo-resistors can operate and present experimental results on implanted piezo-resistors switching high voltages as well as a simple artificial muscle inverter. While gold ion implanted DES are limited by high hysteresis and low sensitivity, they already show promise for a range of applications including hysteretic oscillators and soft generators. With improvements to implanter process control the promise of artificial muscle circuitry for soft smart actuator networks could become a reality.

  18. Local magnitude calibration of the Hellenic Unified Seismic Network

    NASA Astrophysics Data System (ADS)

    Scordilis, E. M.; Kementzetzidou, D.; Papazachos, B. C.

    2016-01-01

    A new relation is proposed for accurate determination of local magnitudes in Greece. This relation is based on a large number of synthetic Wood-Anderson (SWA) seismograms corresponding to 782 regional shallow earthquakes which occurred during the period 2007-2013 and recorded by 98 digital broad-band stations. These stations are installed and operated by the following: (a) the National Observatory of Athens (HL), (b) the Department of Geophysics of the Aristotle University of Thessaloniki (HT), (c) the Seismological Laboratory of the University of Athens (HA), and (d) the Seismological Laboratory of the Patras University (HP). The seismological networks of the above institutions constitute the recently (2004) established Hellenic Unified Seismic Network (HUSN). These records are used to calculate a refined geometrical spreading factor and an anelastic attenuation coefficient, representative for Greece and surrounding areas, proper for accurate calculation of local magnitudes in this region. Individual station corrections depending on the crustal structure variations in their vicinity and possible inconsistencies in instruments responses are also considered in order to further ameliorate magnitude estimation accuracy. Comparison of such calculated local magnitudes with corresponding original moment magnitudes, based on an independent dataset, revealed that these magnitude scales are equivalent for a wide range of values.

  19. Numerical Magnitude Representations Influence Arithmetic Learning

    ERIC Educational Resources Information Center

    Booth, Julie L.; Siegler, Robert S.

    2008-01-01

    This study examined whether the quality of first graders' (mean age = 7.2 years) numerical magnitude representations is correlated with, predictive of, and causally related to their arithmetic learning. The children's pretest numerical magnitude representations were found to be correlated with their pretest arithmetic knowledge and to be…

  20. Reward Magnitude Effects on Temporal Discrimination

    ERIC Educational Resources Information Center

    Galtress, Tiffany; Kirkpatrick, Kimberly

    2010-01-01

    Changes in reward magnitude or value have been reported to produce effects on timing behavior, which have been attributed to changes in the speed of an internal pacemaker in some instances and to attentional factors in other cases. The present experiments therefore aimed to clarify the effects of reward magnitude on timing processes. In Experiment…

  1. Representations of the Magnitudes of Fractions

    ERIC Educational Resources Information Center

    Schneider, Michael; Siegler, Robert S.

    2010-01-01

    We tested whether adults can use integrated, analog, magnitude representations to compare the values of fractions. The only previous study on this question concluded that even college students cannot form such representations and instead compare fraction magnitudes by representing numerators and denominators as separate whole numbers. However,…

  2. Local magnitudes of small contained explosions.

    SciTech Connect

    Chael, Eric Paul

    2009-12-01

    The relationship between explosive yield and seismic magnitude has been extensively studied for underground nuclear tests larger than about 1 kt. For monitoring smaller tests over local ranges (within 200 km), we need to know whether the available formulas can be extrapolated to much lower yields. Here, we review published information on amplitude decay with distance, and on the seismic magnitudes of industrial blasts and refraction explosions in the western U. S. Next we measure the magnitudes of some similar shots in the northeast. We find that local magnitudes ML of small, contained explosions are reasonably consistent with the magnitude-yield formulas developed for nuclear tests. These results are useful for estimating the detection performance of proposed local seismic networks.

  3. Reward magnitude effects on temporal discrimination

    PubMed Central

    Galtress, Tiffany; Kirkpatrick, Kimberly

    2014-01-01

    Changes in reward magnitude or value have been reported to produce effects on timing behavior, which have been attributed to changes in the speed of an internal pacemaker in some instances and to attentional factors in other cases. The present experiments therefore aimed to clarify the effects of reward magnitude on timing processes. In Experiment 1, rats were trained to discriminate a short (2 s) vs. a long (8 s) signal followed by testing with intermediate durations. Then, the reward on short or long trials was increased from 1 to 4 pellets in separate groups. Experiment 2 measured the effect of different reward magnitudes associated with the short vs. long signals throughout training. Finally, Experiment 3 controlled for satiety effects during the reward magnitude manipulation phase. A general flattening of the psychophysical function was evident in all three experiments, suggesting that unequal reward magnitudes may disrupt attention to duration. PMID:24965705

  4. Reward magnitude effects on temporal discrimination

    PubMed Central

    Galtress, Tiffany; Kirkpatrick, Kimberly

    2016-01-01

    Changes in reward magnitude or value have been reported to produce effects on timing behavior, which have been attributed to changes in the speed of an internal pacemaker in some instances and to attentional factors in other cases. The present experiments therefore aimed to clarify the effects of reward magnitude on timing processes. In Experiment 1, rats were trained to discriminate a short (2 s) vs. a long (8 s) signal followed by testing with intermediate durations. Then, the reward on short or long trials was increased from 1 to 4 pellets in separate groups. Experiment 2 measured the effect of different reward magnitudes associated with the short vs. long signals throughout training. Finally, Experiment 3 controlled for satiety effects during the reward magnitude manipulation phase. A general flattening of the psychophysical function was evident in all three experiments, suggesting that unequal reward magnitudes may disrupt attention to duration.

  5. Subdermal Flexible Solar Cell Arrays for Powering Medical Electronic Implants.

    PubMed

    Song, Kwangsun; Han, Jung Hyun; Lim, Taehoon; Kim, Namyun; Shin, Sungho; Kim, Juho; Choo, Hyuck; Jeong, Sungho; Kim, Yong-Chul; Wang, Zhong Lin; Lee, Jongho

    2016-07-01

    A subdermally implantable flexible photovoltatic (IPV) device is proposed for supplying sustainable electric power to in vivo medical implants. Electric properties of the implanted IPV device are characterized in live animal models. Feasibility of this strategy is demonstrated by operating a flexible pacemaker with the subdermal IPV device which generates DC electric power of ≈647 μW under the skin. PMID:27139339

  6. The Magnitude and Energy of Large Earthquakes

    NASA Astrophysics Data System (ADS)

    Purcaru, G.

    2003-12-01

    Several magnitudes were introduced to quantify large earthquakes better and more comprehensive than Ms: Mw (moment magnitude; Kanamori, 1977), ME (strain energy magnitude; Purcaru and Berckhemer, 1978), Mt (tsunami magnitude; Abe, 1979), Mm (mantle magnitude; Okal and Talandier, 1985), Me (seismic energy magnitude; Choy and Boatwright, 1995). Although these magnitudes are still subject to different uncertainties, various kinds of earthquakes can now be better understood in terms or combinations of them. They can also be viewd as mappings of basic source parameters: seismic moment, strain energy, seismic energy, stress drop, under certain assumptions or constraints. We studied a set of about 90 large earthquakes (shallow and deeper) occurred in different tectonic regimes, with more reliable source parameters, and compared them in terms of the above magnitudes. We found large differences between the strain energy (mapped to ME) and seismic energy (mapped to Me), and between ME of events with about the same Mw. This confirms that no 1-to-1 correspondence exists between these magnitudes (Purcaru, 2002). One major cause of differences for "normal" earthquakes is the level of the stress drop over asperities which release and partition the strain energy. We quantify the energetic balance of earthquakes in terms of strain energy Est and its components (fracture (Eg), friction (Ef) and seismic (Es) energy) using an extended Hamilton's principle. The earthquakes are thrust-interplate, strike slip, shallow in-slab, slow/tsunami, deep and continental. The (scaled) strain energy equation we derived is: Est/M0 = (1+e(g,s))(Es/M_0), e(g,s) = Eg/E_s, assuming complete stress drop, using the (static) stress drop variability, and that Est and Es are not in a 1-to-1 correspondence. With all uncertainties, our analysis reveal, for a given seismic moment, a large variation of earthquakes in terms of energies, even in the same seismic region. In view of these, for further understanding

  7. Form-stable silicone gel breast implants.

    PubMed

    Jewell, Mark

    2009-01-01

    This article addresses the question of what is the optimal shape for a breast implant. It is oriented toward processes, system engineering, and operational excellence versus being a treatise on the author's personal technique. PMID:19055963

  8. Retrograde peri-implantitis.

    PubMed

    Mohamed, Jumshad B; Shivakumar, B; Sudarsan, Sabitha; Arun, K V; Kumar, T S S

    2010-01-01

    Retrograde peri-implantitis constitutes an important cause for implant failure. Retrograde peri-implantitis may sometimes prove difficult to identify and hence institution of early treatment may not be possible. This paper presents a report of four cases of (the implant placed developing to) retrograde peri-implantitis. Three of these implants were successfully restored to their fully functional state while one was lost due to extensive damage. The paper highlights the importance of recognizing the etiopathogenic mechanisms, preoperative assessment, and a strong postoperative maintenance protocol to avoid retrograde peri-implant inflammation. PMID:20922082

  9. Measuring radon source magnitude in residential buildings

    SciTech Connect

    Nazaroff, W.W.; Boegel, M.L.; Nero, A.V.

    1981-08-01

    A description is given of procedures used in residences for rapid grab-sample and time-dependent measurements of the air-exchange rate and radon concentration. The radon source magnitude is calculated from the results of simultaneous measurements of these parameters. Grab-sample measurements in three survey groups comprising 101 US houses showed the radon source magnitude to vary approximately log-normally with a geometric mean of 0.37 and a range of 0.01 to 6.0 pCi 1/sup -1/ h/sup -1/. Successive measurements in six houses in the northeastern United States showed considerable variability in source magnitude within a given house. In two of these houses the source magnitude showed a strong correlation with the air-exchange rate, suggesting that soil gas influx can be an important transport process for indoor radon.

  10. Determination of the Meteor Limiting Magnitude

    NASA Technical Reports Server (NTRS)

    Kingery, A.; Blaauw, R.; Cooke, W. J.

    2016-01-01

    The limiting meteor magnitude of a meteor camera system will depend on the camera hardware and software, sky conditions, and the location of the meteor radiant. Some of these factors are constants for a given meteor camera system, but many change between meteor shower or sporadic source and on both long and short timescales. Since the limiting meteor magnitude ultimately gets used to calculate the limiting meteor mass for a given data set, it is important to have an understanding of these factors and to monitor how they change throughout the night, as a 0.5 magnitude uncertainty in limiting magnitude translates to a uncertainty in limiting mass by a factor of two.

  11. New orthopaedic implant management tool for computer-assisted planning, navigation, and simulation: from implant CAD files to a standardized XML-based implant database.

    PubMed

    Sagbo, S; Blochaou, F; Langlotz, F; Vangenot, C; Nolte, L-P; Zheng, G

    2005-01-01

    Computer-Assisted Orthopaedic Surgery (CAOS) has made much progress over the last 10 years. Navigation systems have been recognized as important tools that help surgeons, and various such systems have been developed. A disadvantage of these systems is that they use non-standard formalisms and techniques. As a result, there are no standard concepts for implant and tool management or data formats to store information for use in 3D planning and navigation. We addressed these limitations and developed a practical and generic solution that offers benefits for surgeons, implant manufacturers, and CAS application developers. We developed a virtual implant database containing geometrical as well as calibration information for orthopedic implants and instruments, with a focus on trauma. This database has been successfully tested for various applications in the client/server mode. The implant information is not static, however, because manufacturers periodically revise their implants, resulting in the deletion of some implants and the introduction of new ones. Tracking these continuous changes and keeping CAS systems up to date is a tedious task if done manually. This leads to additional costs for system development, and some errors are inevitably generated due to the huge amount of information that has to be processed. To ease management with respect to implant life cycle, we developed a tool to assist end-users (surgeons, hospitals, CAS system providers, and implant manufacturers) in managing their implants. Our system can be used for pre-operative planning and intra-operative navigation, and also for any surgical simulation involving orthopedic implants. Currently, this tool allows addition of new implants, modification of existing ones, deletion of obsolete implants, export of a given implant, and also creation of backups. Our implant management system has been successfully tested in the laboratory with very promising results. It makes it possible to fill the current gap

  12. Treatment Alternatives to Negotiate Peri-Implantitis

    PubMed Central

    Machtei, Eli E.

    2014-01-01

    Peri-implant diseases are becoming a major health issue in dentistry. Despite the magnitude of this problem and the potential grave consequences, commonly acceptable treatment protocols are missing. Hence, the present paper reviews the literature treatment of peri-implantitis in order to explore their benefits and limitations. Treatment of peri-implantitis may include surgical and nonsurgical approaches, either individually or combined. Nonsurgical therapy is aimed at removing local irritants from the implants' surface with or without surface decontamination and possibly some additional adjunctive therapies agents or devices. Systemic antibiotics may also be incorporated. Surgical therapy is aimed at removing any residual subgingival deposits and additionally reducing the peri-implant pockets depth. This can be done alone or in conjunction with either osseous respective approach or regenerative approach. Finally, if all fails, explantation might be the best alternative in order to arrest the destruction of the osseous structure around the implant, thus preserving whatever is left in this site for future reconstruction. The available literature is still lacking with large heterogeneity in the clinical response thus suggesting possible underlying predisposing conditions that are not all clear to us. Therefore, at present time treatment of peri-implantitis should be considered possible but not necessarily predictable. PMID:26556414

  13. Multiscale Analyses of the Bone-implant Interface

    PubMed Central

    Cha, J.Y.; Pereira, M.D.; Smith, A.A.; Houschyar, K.S.; Yin, X.; Mouraret, S.; Brunski, J.B.

    2015-01-01

    Implants placed with high insertion torque (IT) typically exhibit primary stability, which enables early loading. Whether high IT has a negative impact on peri-implant bone health, however, remains to be determined. The purpose of this study was to ascertain how peri-implant bone responds to strains and stresses created when implants are placed with low and high IT. Titanium micro-implants were inserted into murine femurs with low and high IT using torque values that were scaled to approximate those used to place clinically sized implants. Torque created in peri-implant tissues a distribution and magnitude of strains, which were calculated through finite element modeling. Stiffness tests quantified primary and secondary implant stability. At multiple time points, molecular, cellular, and histomorphometric analyses were performed to quantitatively determine the effect of high and low strains on apoptosis, mineralization, resorption, and collagen matrix deposition in peri-implant bone. Preparation of an osteotomy results in a narrow zone of dead and dying osteocytes in peri-implant bone that is not significantly enlarged in response to implants placed with low IT. Placing implants with high IT more than doubles this zone of dead and dying osteocytes. As a result, peri-implant bone develops micro-fractures, bone resorption is increased, and bone formation is decreased. Using high IT to place an implant creates high interfacial stress and strain that are associated with damage to peri-implant bone and therefore should be avoided to best preserve the viability of this tissue. PMID:25628271

  14. Percutaneous Pulmonary Valve Implantation

    PubMed Central

    Lee, Hyoung-Doo

    2012-01-01

    Pulmonary regurgitation (PR) is a frequent sequelae after repair of tetralogy of Fallot, pulmonary atresia, truncus arteriosus, Rastelli and Ross operation. Due to patient growth and conduit degeneration, these conduits have to be changed frequently due to regurgitation or stenosis. However, morbidity is significant in these repeated operations. To prolong conduit longevity, bare-metal stenting in the right ventricular outflow tract (RVOT) obstruction has been performed. Stenting the RVOT can reduce the right ventricular pressure and symptomatic improvement, but it causes PR with detrimental effects on the right ventricle function and risks of arrhythmia. Percutaneous pulmonary valve implantation has been shown to be a safe and effective treatment for patients with pulmonary valve insufficiency, or stenotic RVOTs. PMID:23170091

  15. Nano hydroxyapatite-coated implants improve bone nanomechanical properties.

    PubMed

    Jimbo, R; Coelho, P G; Bryington, M; Baldassarri, M; Tovar, N; Currie, F; Hayashi, M; Janal, M N; Andersson, M; Ono, D; Vandeweghe, S; Wennerberg, A

    2012-12-01

    Nanostructure modification of dental implants has long been sought as a means to improve osseointegration through enhanced biomimicry of host structures. Several methods have been proposed and demonstrated for creating nanotopographic features; here we describe a nanoscale hydroxyapatite (HA)-coated implant surface and hypothesize that it will hasten osseointegration and improve its quality relative to that of non-coated implants. Twenty threaded titanium alloy implants, half prepared with a stable HA nanoparticle surface and half grit-blasted, acid-etched, and heat-treated (HT), were inserted into rabbit femurs. Pre-operatively, the implants were morphologically and topographically characterized. After 3 weeks of healing, the samples were retrieved for histomorphometry. The nanomechanical properties of the surrounding bone were evaluated by nanoindentation. While both implants revealed similar bone-to-implant contact, the nanoindentation demonstrated that the tissue quality was significantly enhanced around the HA-coated implants, validating the postulated hypothesis. PMID:23045363

  16. A statistical measure of financial crises magnitude

    NASA Astrophysics Data System (ADS)

    Negrea, Bogdan

    2014-03-01

    This paper postulates the concept of financial market energy and provides a statistical measure of the financial market crisis magnitude based on an analogy between earthquakes and market crises. The financial energy released by the market is expressed in terms of trading volume and stock market index returns. A financial “earthquake” occurs if the financial energy released by the market exceeds the estimated threshold of market energy called critical energy. Similar to the Richter scale which is used in seismology in order to measure the magnitude of an earthquake, we propose a financial Gutenberg-Richter relation in order to capture the crisis magnitude and we show that the statistical pattern of the financial market crash is given by two statistical regimes, namely Pareto and Wakeby distributions.

  17. Magnitude and frequency of floods in Alabama

    USGS Publications Warehouse

    Atkins, J. Brian

    1996-01-01

    Methods of estimating flood magnitudes for recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years are described for rural streams in Alabama that are not affected by regulation or urbanization. Flood-frequency characteristics are presented for 198 gaging stations in Alabama having 10 or more years of record through September 1991, that are used in the regional analysis. Regression relations were developed using generalized least-squares regression techniques to estimate flood magnitude and frequency on ungaged streams as a function of the drainage area of a basin. Sites on gaged streams should be weighted with gaging station data that are presented in the report. Graphical relations of peak discharges to drainage areas are also presented for sites along the Alabama, Black Warrior, Cahaba, Choctawhatchee, Conecub, and Tombigbee Rivers. Equations for estimating flood magnitudes on ungaged urban streams (taken from a previous report) that use drainage area and percentage of impervious cover as independent variables also are given.

  18. Immediate implant placement: a case report.

    PubMed

    Chandra Sekar, A; Praveen, M; Saxena, Aarti; Gautam, A

    2012-06-01

    This case report describes extraction of a fractured left maxillary lateral incisor tooth, followed by immediate placement of a dental implant in the prepared socket and temporization by a bonded restoration. The tooth was atraumatically extracted, the socket was prepared to the required depth and a Biohorizon Implant was inserted followed a week later by temporization by a bonded restoration. An impression was made 4 months after implant insertion, and a definitive restoration was placed. The atraumatic operating technique and the immediate insertion of the Implant resulted in the preservation of the hard and soft tissues at the extraction site. The patient exhibited no clinical or radiologic complications through 5 years of clinical monitoring. The dental implant and provisional restoration provided the patient with immediate esthetics, function, comfort, and most importantly preservation of tissues. PMID:23858286

  19. Standardized Loads Acting in Hip Implants.

    PubMed

    Bergmann, Georg; Bender, Alwina; Dymke, Jörn; Duda, Georg; Damm, Philipp

    2016-01-01

    With the increasing success of hip joint replacements, the average age of patients has decreased, patients have become more active and their expectations of the implant durability have risen. Thus, pre-clinical endurance tests on hip implants require defining realistic in vivo loads from younger and more active patients. These loads require simplifications to be applicable for simulator tests and numerical analyses. Here, the contact forces in the joint were measured with instrumented hip implants in ten subjects during nine of the most physically demanding and frequent activities of daily living. Typical levels and directions of average and high joint loads were extracted from the intra- and inter-individually widely varying individual data. These data can also be used to analyse bone remodelling at the implant-bone interface, evaluate tissue straining in finite element studies or validate analytical loading predictions, among other uses. The current ISO standards for endurance tests of implant stems and necks are based on historic analytical data from the 1970s. Comparisons of these test forces with in vivo loads unveiled that their unidirectional orientations deviate from the time-dependent in vivo directions during walking and most other activities. The ISO force for testing the stem is substantially too low while the ISO force for the neck better matches typical in vivo magnitudes. Because the magnitudes and orientations of peak forces substantially vary among the activities, load scenarios that reflect a collection of time-dependent high forces should be applied rather than using unidirectional forces. Based on data from ten patients, proposals for the most demanding activities, the time courses of the contact forces and the required cycle numbers for testing are given here. Friction moments in the joint were measured in addition to the contact forces. The moment data were also standardized and can be applied to wear tests of the implant. It was shown that

  20. Standardized Loads Acting in Hip Implants

    PubMed Central

    Bergmann, Georg; Bender, Alwina; Dymke, Jörn; Duda, Georg; Damm, Philipp

    2016-01-01

    With the increasing success of hip joint replacements, the average age of patients has decreased, patients have become more active and their expectations of the implant durability have risen. Thus, pre-clinical endurance tests on hip implants require defining realistic in vivo loads from younger and more active patients. These loads require simplifications to be applicable for simulator tests and numerical analyses. Here, the contact forces in the joint were measured with instrumented hip implants in ten subjects during nine of the most physically demanding and frequent activities of daily living. Typical levels and directions of average and high joint loads were extracted from the intra- and inter-individually widely varying individual data. These data can also be used to analyse bone remodelling at the implant-bone interface, evaluate tissue straining in finite element studies or validate analytical loading predictions, among other uses. The current ISO standards for endurance tests of implant stems and necks are based on historic analytical data from the 1970s. Comparisons of these test forces with in vivo loads unveiled that their unidirectional orientations deviate from the time-dependent in vivo directions during walking and most other activities. The ISO force for testing the stem is substantially too low while the ISO force for the neck better matches typical in vivo magnitudes. Because the magnitudes and orientations of peak forces substantially vary among the activities, load scenarios that reflect a collection of time-dependent high forces should be applied rather than using unidirectional forces. Based on data from ten patients, proposals for the most demanding activities, the time courses of the contact forces and the required cycle numbers for testing are given here. Friction moments in the joint were measured in addition to the contact forces. The moment data were also standardized and can be applied to wear tests of the implant. It was shown that

  1. Delta Scorpii unusual brightening to first magnitude

    NASA Astrophysics Data System (ADS)

    Sigismondi, Costantino

    2016-01-01

    The Be star delta Scorpii with a range of variability between 2.35 and 1.65 in visible light is having an unusual brightening to magnitude mV=0.8, as measured on 31 Jan 2016 at 3:56 UT and 5:36 UT from Lanciano, Italy.

  2. On the statistical analysis of maximal magnitude

    NASA Astrophysics Data System (ADS)

    Holschneider, M.; Zöller, G.; Hainzl, S.

    2012-04-01

    We show how the maximum expected magnitude within a time horizon [0,T] may be estimated from earthquake catalog data within the context of truncated Gutenberg-Richter statistics. We present the results in a frequentist and in a Bayesian setting. Instead of deriving point estimations of this parameter and reporting its performance in terms of expectation value and variance, we focus on the calculation of confidence intervals based on an imposed level of confidence α. We present an estimate of the maximum magnitude within an observational time interval T in the future, given a complete earthquake catalog for a time period Tc in the past and optionally some paleoseismic events. We argue that from a statistical point of view the maximum magnitude in a time window is a reasonable parameter for probabilistic seismic hazard assessment, while the commonly used maximum possible magnitude for all times does almost certainly not allow the calculation of useful (i.e. non-trivial) confidence intervals. In the context of an unbounded GR law we show, that Jeffreys invariant prior distribtution yields normalizable posteriors. The predictive distribution based on this prior is explicitely computed.

  3. Lamp modulator provides signal magnitude indication

    NASA Technical Reports Server (NTRS)

    Zeman, J. R.

    1970-01-01

    Lamp modulator provides visible indication of presence and magnitude of an audio signal carrying voice or data. It can be made to reflect signal variations of up to 32 decibels. Lamp life is increased by use of a bypass resistor to prevent filament failure.

  4. Fast Regional Magnitude Determination at INGV

    NASA Astrophysics Data System (ADS)

    Michelini, A.; Lomax, A.; Bono, A.; Amato, A.

    2006-12-01

    The recent, very large earthquakes in the Indian Ocean and Indonesia have shown the importance of rapid magnitude determination for tsunami warning. In the Mediterranean region, destructive tsunamis have occurred repeatedly in the past; however, because of the proximity of the tsunami sources to populated coasts, very rapid analysis is necessary for effective warning. Reliable estimates of the earthquake location and size should be available within tens of seconds after the first arriving P-waves are recorded at local and regional distances. Currently in Europe there is no centralized agency such as the PTWC for the Pacific Ocean dedicated to issue tsunami warnings, though, recent initiatives, such as the NEAMTWS (North-East Atlantic and Mediterranean Tsunami Warning System), aim toward the establishment of such an agency. Thus established seismic monitoring centers, such as INGV, Rome, are currently relied upon for rapid earthquake analysis and information dissemination. In this study, we describe the recent, experimental implementation at the INGV seismic center of a procedure for rapid magnitude determination at regional distances based on the Mwp methodology (Tsuboi et al., 1995), which exploits information in the P-wave train. For our Mwp determinations, we have implemented an automatic procedure that windows the relevant part of the seismograms and picks the amplitudes of the first two largest peaks, providing within seconds after each P arrival an estimate of earthquake size. Manual revision is completed using interactive software that presents an analysis with the seismograms, amplitude picks and magnitude estimates. We have compared our Mwp magnitudes for recent earthquakes within the Mediterranean region with Mw determined through the Harvard CMT procedure. For the majority of the events, the Mwp and Mw magnitudes agree closely, indicating that the rapid Mwp estimates forms a useful tool for effective tsunami warning on a regional scale.

  5. Maximum magnitude in the Lower Rhine Graben

    NASA Astrophysics Data System (ADS)

    Vanneste, Kris; Merino, Miguel; Stein, Seth; Vleminckx, Bart; Brooks, Eddie; Camelbeeck, Thierry

    2014-05-01

    Estimating Mmax, the assumed magnitude of the largest future earthquakes expected on a fault or in an area, involves large uncertainties. No theoretical basis exists to infer Mmax because even where we know the long-term rate of motion across a plate boundary fault, or the deformation rate across an intraplate zone, neither predict how strain will be released. As a result, quite different estimates can be made based on the assumptions used. All one can say with certainty is that Mmax is at least as large as the largest earthquake in the available record. However, because catalogs are often short relative to the average recurrence time of large earthquakes, larger earthquakes than anticipated often occur. Estimating Mmax is especially challenging within plates, where deformation rates are poorly constrained, large earthquakes are rarer and variable in space and time, and often occur on previously unrecognized faults. We explore this issue for the Lower Rhine Graben seismic zone where the largest known earthquake, the 1756 Düren earthquake, has magnitude 5.7 and should occur on average about every 400 years. However, paleoseismic studies suggest that earthquakes with magnitudes up to 6.7 occurred during the Late Pleistocene and Holocene. What to assume for Mmax is crucial for critical facilities like nuclear power plants that should be designed to withstand the maximum shaking in 10,000 years. Using the observed earthquake frequency-magnitude data, we generate synthetic earthquake histories, and sample them over shorter intervals corresponding to the real catalog's completeness. The maximum magnitudes appearing most often in the simulations tend to be those of earthquakes with mean recurrence time equal to the catalog length. Because catalogs are often short relative to the average recurrence time of large earthquakes, we expect larger earthquakes than observed to date to occur. In a next step, we will compute hazard maps for different return periods based on the

  6. Urinary incontinence - injectable implant

    MedlinePlus

    Injectable implants are injections of material into the urethra to help control urine leakage ( urinary incontinence ) caused by a ... into the tissue next to the sphincter. The implant procedure is usually done in the hospital. Or ...

  7. Hair implant complications.

    PubMed

    Hanke, C W; Norins, A L; Pantzer, J G; Bennett, J E

    1981-04-01

    Four men who underwent hair implantation for pattern baldness were treated for complications such as infection, foreign-body reaction, pruritus, and scarring. The complications were similar to those reported with synthetic modacrylic fiber implants that have been used for the same purpose. Although we believe this is the first article to report complications from hair implants, the illogical basis of the procedure suggests that complications will occur in many unsuspecting patients who undergo hair implantation. PMID:7009899

  8. Characterization of wear in composite material orthopaedic implants. Part II: The implant/bone interface.

    PubMed

    Albert, K; Schledjewski, R; Harbaugh, M; Bleser, S; Jamison, R; Friedrich, K

    1994-01-01

    Carbon fiber/PEEK polymer (C/PEEK) composite materials are being developed for use as orthopaedic implant materials. Wear is an issue of increasing importance in orthopaedic implants; particulate debris generated by the wearing of biomaterials may be a causal factor leading to osteolysis and implant loosening. Therefore, numerical and experimental studies were completed to characterize the wear of C/PEEK composite materials in comparison to current orthopaedic implant materials. Finite element analyses (FEA) of a composite material hip stem implanted in a femur and loaded at 890 N determined that peak contact stresses will occur at the proximal-medial and distal regions of the implant. These contact stresses were found to be below 1.0 MPa over most of the implant surface; however the peak stress in the proximal-medial region was 1.8 MPa and higher still at the distal portion of the stem. In vivo forces result in contact stress values up to 9.0 MPa. The composite implant exhibited 10-40% lower contact stresses in the distal region compared to a titanium-alloy implant of identical design. Composite material wear samples were slid against porous hydroxylapatite (HA) to simulate the stem/bone interface. An identical series of experiments was run for comparison to a current orthopaedic implant material--Ti6A14V titanium alloy. Two domains of motion were studied; a composite ring-on-HA disc large amplitude sliding wear test; and a composite pin-on-HA disc small amplitude fretting regimen. Nominal contact pressures during testing were 1.4 MPa and 7.6 MPa for sliding and fretting tests, respectively. Fretting and sliding abrasive wear tests resulted in the composite material exhibiting a lower wear rate than the titanium-alloy. The magnitude of the difference was greatly dependent on the contact pressures, sliding amplitudes, and counterface material properties. PMID:7950869

  9. Implantable Heart Aid

    NASA Technical Reports Server (NTRS)

    1984-01-01

    CPI's human-implantable automatic implantable defibrillator (AID) is a heart assist system, derived from NASA's space circuitry technology, that can prevent erratic heart action known as arrhythmias. Implanted AID, consisting of microcomputer power source and two electrodes for sensing heart activity, recognizes onset of ventricular fibrillation (VF) and delivers corrective electrical countershock to restore rhythmic heartbeat.

  10. Behavior of PET implanted by Ti, Ag, Si and C ion using MEVVA implantation

    NASA Astrophysics Data System (ADS)

    Wu, Yuguang; Zhang, Tonghe; Zhang, Yanwen; Zhang, Huixing; Zhang, Xiaoji; Zhou, Gu

    2001-01-01

    Polyethylene terephthalane (PET) has been modified with Ti, Ag, Si and C ions from a metal vapor arc source (MEVVA). Ti, Ag, Si and C ions were implanted with acceleration voltage 40 kV to fluences ranging from 1×10 16 to 2×10 17 cm -2. The surface of implanted PET darkened with increasing ion dose, when the metal ion dose was greater than 1×10 17 cm -2 the color changed to metallic bright. The surface resistance decreases by 5-6 orders of magnitude with increasing dose. The resistivity is stable after long-term storage. The depth of Ti- and Ag-implanted layer is approximately 150 and 80 nm measured by Rutherford backscattering (RBS), respectively. TEM photos revealed the presence of Ti and Ag nano-meter particles on the surface resulting from the high-dose implantation. Ti and Ag ion implantations improved conductivity and wear resistance significantly. The phase and structural changes were obtained by X-ray diffraction (XRD). It can be seen that nano-meter particles of Ti precipitation, TiO 2 and Ti-carbides have been formed in implanted layer. Nano-hardness of implanted PET has been measured by a nano-indenter. The results show that the surface hardness, modulus and wear resistance could be increased.

  11. Subitizing, Magnitude Representation, and Magnitude Retrieval in Deaf and Hearing Adults

    ERIC Educational Resources Information Center

    Bull, Rebecca; Blatto-Vallee, Gary; Fabich, Megan

    2006-01-01

    This study examines basic number processing (subitizing, automaticity, and magnitude representation) as the possible underpinning of mathematical difficulties often evidenced in deaf adults. Hearing and deaf participants completed tasks to assess the automaticity with which magnitude information was activated and retrieved from long-term memory…

  12. Absolute-magnitude distributions of supernovae

    SciTech Connect

    Richardson, Dean; Wright, John; Jenkins III, Robert L.; Maddox, Larry

    2014-05-01

    The absolute-magnitude distributions of seven supernova (SN) types are presented. The data used here were primarily taken from the Asiago Supernova Catalogue, but were supplemented with additional data. We accounted for both foreground and host-galaxy extinction. A bootstrap method is used to correct the samples for Malmquist bias. Separately, we generate volume-limited samples, restricted to events within 100 Mpc. We find that the superluminous events (M{sub B} < –21) make up only about 0.1% of all SNe in the bias-corrected sample. The subluminous events (M{sub B} > –15) make up about 3%. The normal Ia distribution was the brightest with a mean absolute blue magnitude of –19.25. The IIP distribution was the dimmest at –16.75.

  13. Asteroid absolute magnitudes and slope parameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1991-01-01

    A new listing of absolute magnitudes (H) and slope parameters (G) has been created and published in the Minor Planet Circulars; this same listing will appear in the 1992 Ephemerides of Minor Planets. Unlike previous listings, the values of the current list were derived from fits of data at the V band. All observations were reduced in the same fashion using, where appropriate, a single basis default value of 0.15 for the slope parameter. Distances and phase angles were computed for each observation. The data for 113 asteroids was of sufficiently high quality to permit derivation of their H and G. These improved absolute magnitudes and slope parameters will be used to deduce the most reliable bias-corrected asteroid size-frequency distribution yet made.

  14. Implantable Myoelectric Sensors (IMESs) for Intramuscular Electromyogram Recording

    PubMed Central

    Weir, Richard F. ff.; Troyk, Phil R.; DeMichele, Glen A.; Kerns, Douglas A.; Schorsch, Jack F.; Maas, Huub

    2011-01-01

    We have developed a multichannel electrogmyography sensor system capable of receiving and processing signals from up to 32 implanted myoelectric sensors (IMES). The appeal of implanted sensors for myoelectric control is that electromyography (EMG) signals can be measured at their source providing relatively cross-talk-free signals that can be treated as independent control sites. An external telemetry controller receives telemetry sent over a transcutaneous magnetic link by the implanted electrodes. The same link provides power and commands to the implanted electrodes. Wireless telemetry of EMG signals from sensors implanted in the residual musculature eliminates the problems associated with percutaneous wires, such as infection, breakage, and marsupialization. Each implantable sensor consists of a custom-designed application-specified integrated circuit that is packaged into a bio-compatible RF BION capsule from the Alfred E. Mann Foundation. Implants are designed for permanent long-term implantation with no servicing requirements. We have a fully operational system. The system has been tested in animals. Implants have been chronically implanted in the legs of three cats and are still completely operational four months after implantation. PMID:19224729

  15. The secular variation of cometary magnitude

    NASA Astrophysics Data System (ADS)

    Hughes, D. W.; Daniels, P. A.

    1983-03-01

    This paper calculates the mean variation in absolute magnitude per perihelion passage, ΔH10, for short-period comets from the data of Vsekhsvyatskii and finds a value of 0.30 ± 0.06. Other mechanisms used for estimating cometary decay are reviewed an it is concluded that a more probable value for ΔH10 is about 0.002. Reasons for the discrepancy between these two values are given.

  16. Is the use of computer navigation in total knee arthroplasty improving implant positioning and function? A comparative study of 198 knees operated at a Norwegian district hospital

    PubMed Central

    2013-01-01

    Background There are few Scandinavian studies on the effect of computer assisted orthopedic surgery (CAOS) in total knee arthroplasty (TKA), compared to conventional technique (CON), and there is little information on effects in pain and function scores. This retrospective study has evaluated the effects of CAOS on radiological parameters and pain, function and quality of life after primary TKA. Methods 198 primary TKAs were operated by one surgeon in two district hospitals; 103 CAOS and 95 CON. The groups were evaluated based on 3 months post-operative radiographs and a questionnaire containing the knee osteoarthritis outcome score (KOOS), the EQ-5D index score and a visual analogue scale (VAS) two years after surgery. Multiple linear regression method was used to investigate possible impact from exposure (CON or CAOS). Results On hip-knee-ankle radiographs, 20% of measurements were > ±3° of neutral in the CAOS group and 25% in the CON group (p = 0.37). For the femoral component, the number was 5% for CAOS and 18% for CON (p < 0.01). For the tibial component, the difference was not statistically significant (p = 0.58). In the sagittal plane, the surgeon tended to apply more femoral flexion and more posterior tibial slope with CAOS. We observed no statistically or clinically significant difference in KOOS score, VAS or ∆EQ-5D (all p values >0.05), but there was a trend towards better scores for CAOS. Operation time was 3 minutes longer for CON (p = 0.37). Conclusions CAOS can improve radiological measurements in primary TKA, and makes it possible to adjust component placement to the patient’s anatomy. Over-all, the two methods are equal in pain, function and quality-of-life scores. PMID:24228727

  17. Magnitude and frequency of floods in Washington

    USGS Publications Warehouse

    Cummans, J.E.; Collings, Michael R.; Nasser, Edmund George

    1975-01-01

    Relations are provided to estimate the magnitude and frequency of floods on Washington streams. Annual-peak-flow data from stream gaging stations on unregulated streams having 1 years or more of record were used to determine a log-Pearson Type III frequency curve for each station. Flood magnitudes having recurrence intervals of 2, 5, i0, 25, 50, and 10years were then related to physical and climatic indices of the drainage basins by multiple-regression analysis using the Biomedical Computer Program BMDO2R. These regression relations are useful for estimating flood magnitudes of the specified recurrence intervals at ungaged or short-record sites. Separate sets of regression equations were defined for western and eastern parts of the State, and the State was further subdivided into 12 regions in which the annual floods exhibit similar flood characteristics. Peak flows are related most significantly in western Washington to drainage-area size and mean annual precipitation. In eastern Washington-they are related most significantly to drainage-area size, mean annual precipitation, and percentage of forest cover. Standard errors of estimate of the estimating relations range from 25 to 129 percent, and the smallest errors are generally associated with the more humid regions.

  18. Local magnitude scale for earthquakes in Turkey

    NASA Astrophysics Data System (ADS)

    Kılıç, T.; Ottemöller, L.; Havskov, J.; Yanık, K.; Kılıçarslan, Ö.; Alver, F.; Özyazıcıoğlu, M.

    2016-06-01

    Based on the earthquake event data accumulated by the Turkish National Seismic Network between 2007 and 2013, the local magnitude (Richter, Ml) scale is calibrated for Turkey and the close neighborhood. A total of 137 earthquakes (Mw > 3.5) are used for the Ml inversion for the whole country. Three Ml scales, whole country, East, and West Turkey, are developed, and the scales also include the station correction terms. Since the scales for the two parts of the country are very similar, it is concluded that a single Ml scale is suitable for the whole country. Available data indicate the new scale to suffer from saturation beyond magnitude 6.5. For this data set, the horizontal amplitudes are on average larger than vertical amplitudes by a factor of 1.8. The recommendation made is to measure Ml amplitudes on the vertical channels and then add the logarithm scale factor to have a measure of maximum amplitude on the horizontal. The new Ml is compared to Mw from EMSC, and there is almost a 1:1 relationship, indicating that the new scale gives reliable magnitudes for Turkey.

  19. Influence of cochlear implantation on vestibular function.

    PubMed

    Chen, Xiulan; Chen, Xiaohua; Zhang, Fan; Qin, Zhaobing

    2016-07-01

    Conclusion Vestibular function in patients can be damaged following cochlear implantation. Therefore, assessing the pre-operative vestibular status, carefully choosing the side of implantation, and preserving function by using minimally invasive surgical techniques are important. Objectives The aim of this study was to assess the influence of cochlear implantation on vestibular function in patients with severe and profound sensorineural hearing loss, and to analyze a possible correlation between the changes in vestibular testing and post-operative vestibular symptoms. Methods Thirty-four patients were evaluated for vestibular function using the cervical and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP, respectively), and 29 patients underwent caloric tests pre-operatively and 4 weeks post-operatively. Results Before surgery, the cVEMPs were recorded bilaterally in 22 patients, unilaterally in eight patients, and absent bilaterally in four patients. The oVEMPs were recorded bilaterally in 19 patients, unilaterally in six patients, and absent bilaterally in nine patients. After implantation, the cVEMPs were absent in 10 patients and the oVEMPs were absent in seven patients on the implanted side. Caloric tests demonstrated canal paresis in 17 patients, and normal responses were recorded in 12 of the 29 patients pre-operatively. There was a significant decrease post-implantation in the ear implanted, with the exception of two patients. Two patients presented with vertigo and another two patients reported slight unsteadiness post-operatively, but all symptoms resolved within 7 days. The impaired vestibular function did not correlate with vestibular symptoms, age, or gender. Function on the contralateral side remained unaffected. PMID:27008103

  20. Evolution and magnitudes of candidate Planet Nine

    NASA Astrophysics Data System (ADS)

    Linder, Esther F.; Mordasini, Christoph

    2016-04-01

    Context. The recently renewed interest in a possible additional major body in the outer solar system prompted us to study the thermodynamic evolution of such an object. We assumed that it is a smaller version of Uranus and Neptune. Aims: We modeled the temporal evolution of the radius, temperature, intrinsic luminosity, and the blackbody spectrum of distant ice giant planets. The aim is also to provide estimates of the magnitudes in different bands to assess whether the object might be detectable. Methods: Simulations of the cooling and contraction were conducted for ice giants with masses of 5, 10, 20, and 50 M⊕ that are located at 280, 700, and 1120 AU from the Sun. The core composition, the fraction of H/He, the efficiency of energy transport, and the initial luminosity were varied. The atmospheric opacity was set to 1, 50, and 100 times solar metallicity. Results: We find for a nominal 10 M⊕ planet at 700 AU at the current age of the solar system an effective temperature of 47 K, much higher than the equilibrium temperature of about 10 K, a radius of 3.7 R⊕, and an intrinsic luminosity of 0.006 L♃. It has estimated apparent magnitudes of Johnson V, R, I, L, N, Q of 21.7, 21.4, 21.0, 20.1, 19.9, and 10.7, and WISE W1-W4 magnitudes of 20.1, 20.1, 18.6, and 10.2. The Q and W4 band and other observations longward of about 13 μm pick up the intrinsic flux. Conclusions: If candidate Planet 9 has a significant H/He layer and an efficient energy transport in the interior, then its luminosity is dominated by the intrinsic contribution, making it a self-luminous planet. At a likely position on its orbit near aphelion, we estimate for a mass of 5, 10, 20, and 50 M⊕ a V magnitude from the reflected light of 24.3, 23.7, 23.3, and 22.6 and a Q magnitude from the intrinsic radiation of 14.6, 11.7, 9.2, and 5.8. The latter would probably have been detected by past surveys.

  1. Evolution and magnitudes of candidate Planet Nine

    NASA Astrophysics Data System (ADS)

    Linder, Esther F.; Mordasini, Christoph

    2016-05-01

    Context. The recently renewed interest in a possible additional major body in the outer solar system prompted us to study the thermodynamic evolution of such an object. We assumed that it is a smaller version of Uranus and Neptune. Aims: We modeled the temporal evolution of the radius, temperature, intrinsic luminosity, and the blackbody spectrum of distant ice giant planets. The aim is also to provide estimates of the magnitudes in different bands to assess whether the object might be detectable. Methods: Simulations of the cooling and contraction were conducted for ice giants with masses of 5, 10, 20, and 50 M⊕ that are located at 280, 700, and 1120 AU from the Sun. The core composition, the fraction of H/He, the efficiency of energy transport, and the initial luminosity were varied. The atmospheric opacity was set to 1, 50, and 100 times solar metallicity. Results: We find for a nominal 10 M⊕ planet at 700 AU at the current age of the solar system an effective temperature of 47 K, much higher than the equilibrium temperature of about 10 K, a radius of 3.7 R⊕, and an intrinsic luminosity of 0.006 L♃. It has estimated apparent magnitudes of Johnson V, R, I, L, N, Q of 21.7, 21.4, 21.0, 20.1, 19.9, and 10.7, and WISE W1-W4 magnitudes of 20.1, 20.1, 18.6, and 10.2. The Q and W4 band and other observations longward of about 13 μm pick up the intrinsic flux. Conclusions: If candidate Planet 9 has a significant H/He layer and an efficient energy transport in the interior, then its luminosity is dominated by the intrinsic contribution, making it a self-luminous planet. At a likely position on its orbit near aphelion, we estimate for a mass of 5, 10, 20, and 50 M⊕ a V magnitude from the reflected light of 24.3, 23.7, 23.3, and 22.6 and a Q magnitude from the intrinsic radiation of 14.6, 11.7, 9.2, and 5.8. The latter would probably have been detected by past surveys.

  2. Rapid determination of the energy magnitude Me

    NASA Astrophysics Data System (ADS)

    di Giacomo, D.; Parolai, S.; Bormann, P.; Saul, J.; Grosser, H.; Wang, R.; Zschau, J.

    2009-04-01

    The magnitude of an earthquake is one of the most used parameters to evaluate the earthquake's damage potential. However, many magnitude scales developed over the past years have different meanings. Among the non-saturating magnitude scales, the energy magnitude Me is related to a well defined physical parameter of the seismic source, that is the radiated seismic energy ES (e.g. Bormann et al., 2002): Me = 2/3(log10 ES - 4.4). Me is more suitable than the moment magnitude Mw in describing an earthquake's shaking potential (Choy and Kirby, 2004). Indeed, Me is calculated over a wide frequency range of the source spectrum and represents a better measure of the shaking potential, whereas Mw is related to the low-frequency asymptote of the source spectrum and is a good measure of the fault size and hence of the static (tectonic) effect of an earthquake. The calculation of ES requires the integration over frequency of the squared P-waves velocity spectrum corrected for the energy loss experienced by the seismic waves along the path from the source to the receivers. To accout for the frequency-dependent energy loss, we computed spectral amplitude decay functions for different frequenciesby using synthetic Green's functions (Wang, 1999) based on the reference Earth model AK135Q (Kennett et al., 1995; Montagner and Kennett, 1996). By means of these functions the correction for the various propagation effects of the recorded P-wave velocity spectra is performed in a rapid and robust way, and the calculation of ES, and hence of Me, can be computed at the single station. We analyse teleseismic broadband P-waves signals in the distance range 20°-98°. We show that our procedure is suitable for implementation in rapid response systems since it could provide stable Me determinations within 10-15 minutes after the earthquake's origin time. Indeed, we use time variable cumulative energy windows starting 4 s after the first P-wave arrival in order to include the earthquake rupture

  3. Trends in Cochlear Implants

    PubMed Central

    Zeng, Fan-Gang

    2004-01-01

    More than 60,000 people worldwide use cochlear implants as a means to restore functional hearing. Although individual performance variability is still high, an average implant user can talk on the phone in a quiet environment. Cochlear-implant research has also matured as a field, as evidenced by the exponential growth in both the patient population and scientific publication. The present report examines current issues related to audiologic, clinical, engineering, anatomic, and physiologic aspects of cochlear implants, focusing on their psychophysical, speech, music, and cognitive performance. This report also forecasts clinical and research trends related to presurgical evaluation, fitting protocols, signal processing, and postsurgical rehabilitation in cochlear implants. Finally, a future landscape in amplification is presented that requires a unique, yet complementary, contribution from hearing aids, middle ear implants, and cochlear implants to achieve a total solution to the entire spectrum of hearing loss treatment and management. PMID:15247993

  4. Apparent magnitude of earthshine: a simple calculation

    NASA Astrophysics Data System (ADS)

    Agrawal, Dulli Chandra

    2016-05-01

    The Sun illuminates both the Moon and the Earth with practically the same luminous fluxes which are in turn reflected by them. The Moon provides a dim light to the Earth whereas the Earth illuminates the Moon with somewhat brighter light which can be seen from the Earth and is called earthshine. As the amount of light reflected from the Earth depends on part of the Earth and the cloud cover, the strength of earthshine varies throughout the year. The measure of the earthshine light is luminance, which is defined in photometry as the total luminous flux of light hitting or passing through a surface. The expression for the earthshine light in terms of the apparent magnitude has been derived for the first time and evaluated for two extreme cases; firstly, when the Sun’s rays are reflected by the water of the oceans and secondly when the reflector is either thick clouds or snow. The corresponding values are -1.30 and -3.69, respectively. The earthshine value -3.22 reported by Jackson lies within these apparent magnitudes. This paper will motivate the students and teachers of physics to look for the illuminated Moon by earthlight during the waning or waxing crescent phase of the Moon and to reproduce the expressions derived here by making use of the inverse-square law of radiation, Planck’s expression for the power in electromagnetic radiation, photopic spectral luminous efficiency function and expression for the apparent magnitude of a body in terms of luminous fluxes.

  5. The intensities and magnitudes of volcanic eruptions

    USGS Publications Warehouse

    Sigurdsson, H.

    1991-01-01

    Ever since 1935, when C.F Richter devised the earthquake magnitude scale that bears his name, seismologists have been able to view energy release from earthquakes in a systematic and quantitative manner. The benefits have been obvious in terms of assessing seismic gaps and the spatial and temporal trends of earthquake energy release. A similar quantitative treatment of volcanic activity is of course equally desirable, both for gaining a further understanding of the physical principles of volcanic eruptions and for volcanic-hazard assessment. A systematic volcanologic data base would be of great value in evaluating such features as volcanic gaps, and regional and temporal trends in energy release.  

  6. Precise Relative Earthquake Magnitudes from Cross Correlation

    DOE PAGESBeta

    Cleveland, K. Michael; Ammon, Charles J.

    2015-04-21

    We present a method to estimate precise relative magnitudes using cross correlation of seismic waveforms. Our method incorporates the intercorrelation of all events in a group of earthquakes, as opposed to individual event pairings relative to a reference event. This method works well when a reliable reference event does not exist. We illustrate the method using vertical strike-slip earthquakes located in the northeast Pacific and Panama fracture zone regions. Our results are generally consistent with the Global Centroid Moment Tensor catalog, which we use to establish a baseline for the relative event sizes.

  7. An Energy Rate Magnitude for Large Earthquakes

    NASA Astrophysics Data System (ADS)

    Newman, A. V.; Convers, J. A.

    2008-12-01

    The ability to rapidly assess the approximate size of very large and destructive earthquakes is important for early hazard mitigation from both strong shaking and potential tsunami generation. Using a methodology to rapidly determine earthquake energy and duration using teleseismic high-frequency energy, we develop an adaptation to approximate the magnitude of a very large earthquake before the full duration of rupture can be measured at available teleseismic stations. We utilize available vertical component data to analyze the high-frequency energy growth between 0.5 and 2 Hz, minimizing the effect of later arrivals that are mostly attenuated in this range. Because events smaller than M~6.5 occur rapidly, this method is most adequate for larger events, whose rupture duration exceeds ~20 seconds. Using a catalog of about 200 large and great earthquakes we compare the high-frequency energy rate (· Ehf) to the total broad- band energy (· Ebb) to find a relationship for: Log(· Ehf)/Log(Ebb)≍ 0.85. Hence, combining this relation to the broad-band energy magnitude (Me) [Choy and Boatwright, 1995], yields a new high-frequency energy rate magnitude: M· E=⅔ log10(· Ehf)/0.85-2.9. Such an empirical approach can thus be used to obtain a reasonable assessment of an event magnitude from the initial estimate of energy growth, even before the arrival of the full direct-P rupture signal. For large shallow events thus far examined, the M· E predicts the ultimate Me to within ±0.2 units of M. For fast rupturing deep earthquakes M· E overpredicts, while for slow-rupturing tsunami earthquakes M· E underpredicts Me likely due to material strength changes at the source rupture. We will report on the utility of this method in both research mode, and in real-time scenarios when data availability is limited. Because the high-frequency energy is clearly discernable in real-time, this result suggests that the growth of energy can be used as a good initial indicator of the

  8. Major Intrahepatic Veno-Venous Fistula after Fontan Operation Treated by Transcatheter Implantation of Amplatzer Septal Occluder through Internal Jugular Vein.

    PubMed

    Guzeltas, Alper; Tanidir, Ibrahim Cansaran; Saygi, Murat

    2016-04-01

    Six months after undergoing a Fontan operation, a 7-year-old boy with right atrial isomerism and a single functional ventricle was admitted to our emergency department with cyanosis. Emergency cardiac catheterization revealed a large veno-venous fistula that began in a left hepatic vein, connected to the left accessory hepatic veins, and drained into the common atrium, resulting in desaturation. The fistula was occluded proximally with an Amplatzer septal occluder, with satisfying results; the patient's systemic arterial saturation decreased during his hospital stay. Three weeks after the first intervention, a second procedure was performed to retrieve the first device and to close the fistula distally. Multiple attempts with different types of gooseneck snares and a bioptome catheter failed to retrieve the first device, so a telescopic method was used to re-screw it. Using a Mullins long sheath and delivery sheath, the delivery cable was manipulated to fit into the slot of the end screw, and the cable was rotated gently in a clockwise direction to re-screw the device. Then, another Amplatzer septal occluder was placed at the distal end of the fistula. In conclusion, distal transcatheter occlusion of intrahepatic veno-venous fistulas might lead to better clinical outcomes in selected patients. Amplatzer septal occluder device can be retrieve without any complication within three weeks. PMID:27556319

  9. Computer methods for automating preoperative dental implant planning: implant positioning and size assignment.

    PubMed

    Galanis, Christos C; Sfantsikopoulos, Michael M; Koidis, Petros T; Kafantaris, Nikolaos M; Mpikos, Pavlos G

    2007-04-01

    The paper presents computer-aided methods that allocate a dental implant and suggest its size, during the pre-operative planning stage, in conformance with introduced optimization criteria and established clinical requirements. Based on computed tomography data of the jaw and prosthesis anatomy, single tooth cases are planned for the best-suited implant insertion at a user-defined region. An optimum implantation axis line is produced and cylindrical implants of various candidate sizes are then automatically positioned, while their occlusal end is leveled to bone ridge, and evaluated. Radial safety margins are used for the assessment of the implant safety distance from neighboring anatomical structures and bone quantity and quality are estimated and taken into consideration. A case study demonstrates the concept and allows for its discussion. PMID:17267066

  10. Optical imaging and information storage in ion implanted ferroelectric ceramics

    SciTech Connect

    Peercy, P.S.; Land, C.E.

    1981-11-01

    Photographic images can be stored in ferroelectric-phase lead lanthanum zirconate titanate (PLZT) ceramics using a novel photoferroelectric effect. These images are nonvolatile but erasable and can be switched from positive to negative by application of an electric field. We have found that the photosensitivity of ferroelectric PLZT is dramatically improved by ion implantation into the surface exposed to image light. For example, the intrinsic photosensitivity to near-UV light is increased by as much as four orders of magnitude by coimplantation with Ar and Ne. The increased photosensitivity results from implantation-induced decreases in dark conductivity and dielectric constant in the implanted layer. Furthermore, the increased photoferroelectric sensitivity has recently been extended from the near-UV to the visible spectrum by implants of Al and Cr. Ion-implanted PLZT is the most sensitive, nonvolatile, selectively-erasable image storage medium currently known.

  11. Extreme Magnitude Earthquakes and their Economical Consequences

    NASA Astrophysics Data System (ADS)

    Chavez, M.; Cabrera, E.; Ashworth, M.; Perea, N.; Emerson, D.; Salazar, A.; Moulinec, C.

    2011-12-01

    The frequency of occurrence of extreme magnitude earthquakes varies from tens to thousands of years, depending on the considered seismotectonic region of the world. However, the human and economic losses when their hypocenters are located in the neighborhood of heavily populated and/or industrialized regions, can be very large, as recently observed for the 1985 Mw 8.01 Michoacan, Mexico and the 2011 Mw 9 Tohoku, Japan, earthquakes. Herewith, a methodology is proposed in order to estimate the probability of exceedance of: the intensities of extreme magnitude earthquakes, PEI and of their direct economical consequences PEDEC. The PEI are obtained by using supercomputing facilities to generate samples of the 3D propagation of extreme earthquake plausible scenarios, and enlarge those samples by Monte Carlo simulation. The PEDEC are computed by using appropriate vulnerability functions combined with the scenario intensity samples, and Monte Carlo simulation. An example of the application of the methodology due to the potential occurrence of extreme Mw 8.5 subduction earthquakes on Mexico City is presented.

  12. Strong motion duration and earthquake magnitude relationships

    SciTech Connect

    Salmon, M.W.; Short, S.A.; Kennedy, R.P.

    1992-06-01

    Earthquake duration is the total time of ground shaking from the arrival of seismic waves until the return to ambient conditions. Much of this time is at relatively low shaking levels which have little effect on seismic structural response and on earthquake damage potential. As a result, a parameter termed ``strong motion duration`` has been defined by a number of investigators to be used for the purpose of evaluating seismic response and assessing the potential for structural damage due to earthquakes. This report presents methods for determining strong motion duration and a time history envelope function appropriate for various evaluation purposes, for earthquake magnitude and distance, and for site soil properties. There are numerous definitions of strong motion duration. For most of these definitions, empirical studies have been completed which relate duration to earthquake magnitude and distance and to site soil properties. Each of these definitions recognizes that only the portion of an earthquake record which has sufficiently high acceleration amplitude, energy content, or some other parameters significantly affects seismic response. Studies have been performed which indicate that the portion of an earthquake record in which the power (average rate of energy input) is maximum correlates most closely with potential damage to stiff nuclear power plant structures. Hence, this report will concentrate on energy based strong motion duration definitions.

  13. Silicone breast implant materials.

    PubMed

    Daniels, A U

    2012-01-01

    This opinion article has been written on request because of the recent public controversy over silicone breast implants produced by a now-defunct company, Poly Implant Prosthese (PIP) in France. More than 300,000 PIP devices have been implanted. The purposes of my article are to (1.) provide a general overview of silicone breast implant materials, (2.) to describe the general safety of these materials as reported to date, and (3.) to summarise current publicly available information about these aspects of the PIP prostheses. The materials covered are the silicone rubber from which the implant shells are made and the silicone gel used to fill the shell. The materials safety issues are biocompatibility (especially of the gel) and biodurability of the shell. The literature reviewed indicates that biocompatibility is not an issue with other current generation implants. However, biodurability is. A rough estimate of implant shell rupture rate is ~10+% at 10 years. Information is still emerging about the PIP implants. Initial regulatory disclosures suggest the PIP implants may have both biocompatibility and biodurability problems. They also suggest that PIP implants may have been produced using silicone materials not certified as medical grade. Governmental health and regulatory agencies are just now in the process of deciding what actions should be taken to protect patients. PMID:22826101

  14. In-vivo orthopedic implant diagnostic device for sensing load, wear, and infection

    DOEpatents

    Evans, III, Boyd McCutchen; Thundat, Thomas G.; Komistek, Richard D.; Dennis, Douglas A.; Mahfouz, Mohamed

    2006-08-29

    A device for providing in vivo diagnostics of loads, wear, and infection in orthopedic implants having at least one load sensor associated with the implant, at least one temperature sensor associated with the implant, at least one vibration sensor associated with the implant, and at least one signal processing device operatively coupled with the sensors. The signal processing device is operable to receive the output signal from the sensors and transmit a signal corresponding with the output signal.

  15. Rapid determination of the energy magnitude Me

    NASA Astrophysics Data System (ADS)

    di Giacomo, D.; Parolai, S.; Bormann, P.; Grosser, H.; Saul, J.; Wang, R.; Zschau, J.

    2009-12-01

    The magnitude of an earthquake is one of the most used parameters to evaluate the earthquake’s damage potential. Among the non-saturating magnitude scales, the energy magnitude Me is related to a well defined physical parameter of the seismic source, that is the radiated seismic energy Es (e.g. Bormann et al., 2002): Me = 2/3(log10 Es - 4.4). Me is more suitable than the moment magnitude Mw in describing an earthquake's shaking potential (Choy and Kirby, 2004). Indeed, Me is calculated over a wide frequency range of the source spectrum and represents a better measure of the shaking potential, whereas Mw is related to the low-frequency asymptote of the source spectrum and is a good measure of the fault size and hence of the static (tectonic) effect of an earthquake. We analyse teleseismic broadband P-waves signals in the distance range 20°-98° to calculate Es. To correct the frequency-dependent energy loss experienced by the P-waves during the propagation path, we use pre-calculated spectral amplitude decay functions for different frequencies obtained from numerical simulations of Green’s functions (Wang, 1999) given the reference Earth model AK135Q (Kennett et al., 1995; Montagner and Kennett, 1996). By means of these functions the correction for the various propagation effects of the recorded P-wave velocity spectra is performed in a rapid and robust way, and the calculation of ES, and hence of Me, can be computed at the single station. We show that our procedure is suitable for implementation in rapid response systems since it could provide stable Me determinations within 10-15 minutes after the earthquake’s origin time, even in case of great earthquakes. We tested our procedure for a large dataset composed by about 770 earthquakes globally distributed in the Mw range 5.5-9.3 recorded at the broadband stations managed by the IRIS, GEOFON, and GEOSCOPE global networks, as well as other regional seismic networks. Me and Mw express two different aspects of

  16. Orthodontic mechanics using mini-implant measured by FBG

    NASA Astrophysics Data System (ADS)

    Trannin, Pamela G.; Milczewski, Maura S.; de Oliveira, Walmir; Guariza Filho, Odilon; Lopes, Stephani C. P. S.; Kalinowski, Hypolito J.

    2015-07-01

    The magnitude of the force generated during orthodontic mechanics anchored in mini-implant in a maxilla model was analyzed. Data was collected during the insertion of the mini-implant and at the moment of applying forces to the structure of the maxilla and dentition. To obtain quantitative results, the Fibre Bragg Gratings (FBG) were inserted in an elastomeric material reproducing a maxilla model. It was observed levels of forces of approximately 3,78N next to the root of first premolar by the insertion of the mini-implant and different levels of the force to different orthodontic mechanics applied on the dental system.

  17. Tritium implantation in the accelerator production of tritium device

    SciTech Connect

    Kidman, R.B.

    1997-11-01

    We briefly describe the methods we have developed to compute the magnitude and spatial distribution of born and implanted tritons and protons in the Accelerator Production of Tritium (AFT) device. The methods are verified against experimental measurements and then used to predict that 16% of the tritium is implanted in the walls of the APT distribution tubes. The methods are also used to estimate the spatial distribution of implanted tritium, which will be required for determining the possible diffusion of tritium out of the walls and back into the gas stream.

  18. Reading the Small Print – Labelling Recommendations for Orthopaedic Implants

    PubMed Central

    Haene, Roger A; Sandhu, Ranbir S; Baxandall, Richard

    2009-01-01

    INTRODUCTION There exist, currently, no clear guidelines regarding standards for surgical implant labelling. Dimensions of the laminar flow canopies in orthopaedic use fixes the distance at which implant labels can be read. Mistakes when reading the label on an implant box can pose health risks for patients, and financial consequences for medical institutions. SUBJECTS AND METHODS Using scientifically validated tools such as the Snellen Chart Formula, a theoretical minimum standard for text on implant labels was reached. This theoretical standard was then tested under real operating conditions. After discovering a minimum practical standard for implant labels, the authors then audited current labels in use on a wide range of orthopaedic implant packages. Furthermore, other non-text-related labelling problems were also noted. RESULTS There is a definite minimum standard which should be observed when implant labels are manufactured. Implants in current use bear labels on the packaging that are of an insufficient standard to ensure patient safety in theatre. CONCLUSIONS The authors have established text parameters that will increase the legibility of implant labels. In the interests of improving risk management in theatre, therefore, the authors propose a standard for orthopaedic implant labelling, and believe this will provide a useful foundation for further discussion between the orthopaedic community and implant manufacturers. PMID:19686615

  19. Composite implants coated with biodegradable polymers prevent stimulating tumor progression

    NASA Astrophysics Data System (ADS)

    Litviakov, N. V.; Tverdokhlebov, S. I.; Perelmuter, V. M.; Kulbakin, D. E.; Bolbasov, E. N.; Tsyganov, M. M.; Zheravin, A. A.; Svetlichnyi, V. A.; Cherdyntseva, N. V.

    2016-08-01

    In this experiment we studied oncologic safety of model implants created using the solution blow spinning method with the use of the PURASORB PL-38 polylactic acid polymer and organic mineral filler which was obtained via laser ablation of a solid target made of dibasic calcium phosphate dihydrate. For this purpose the implant was introduced into the area of Wistar rats' iliums, and on day 17 after the surgery the Walker sarcoma was transplanted into the area of the implant. We evaluated the implant's influence on the primary tumor growth, hematogenous and lymphogenous metastasis of the Walker sarcoma. In comparison with sham operated animals the implant group demonstrated significant inhibition of hematogenous metastasis on day 34 after the surgery. The metastasis inhibition index (MII) equaled 94% and the metastases growth inhibition index (MGII) equaled 83%. The metastasis frequency of the Walker sarcoma in para aortic lymph nodes in the implant group was not statistically different from the control frequency; there was also no influence of the implant on the primary tumor growth noted. In case of the Walker sarcoma transplantation into the calf and the palmar pad of the ipsilateral limb to the one with the implant in the ilium, we could not note any attraction of tumor cells to the implant area, i.e. stimulation of the Walker sarcoma relapse by the implant. Thus, the research concluded that the studied implant meets the requirements of oncologic safety.

  20. Morphology and Absolute Magnitudes of the SDSS DR7 QSOs

    NASA Astrophysics Data System (ADS)

    Coelho, B.; Andrei, A. H.; Antón, S.

    2014-10-01

    The ESA mission Gaia will furnish a complete census of the Milky Way, delivering astrometrics, dynamics, and astrophysics information for 1 billion stars. Operating in all-sky repeated survey mode, Gaia will also provide measurements of extra-galactic objects. Among the later there will be at least 500,000 QSOs that will be used to build the reference frame upon which the several independent observations will be combined and interpreted. Not all the QSOs are equally suited to fulfill this role of fundamental, fiducial grid-points. Brightness, morphology, and variability define the astrometric error budget for each object. We made use of 3 morphological parameters based on the PSF sharpness, circularity and gaussianity, which enable us to distinguish the "real point-like" QSOs. These parameters are being explored on the spectroscopically certified QSOs of the SDSS DR7, to compare the performance against other morphology classification schemes, as well as to derive properties of the host galaxy. We present a new method, based on the Gaia quasar database, to derive absolute magnitudes, on the SDSS filters domain. The method can be extrapolated all over the optical window, including the Gaia filters. We discuss colors derived from SDSS apparent magnitudes and colors based on absolute magnitudes that we obtained tanking into account corrections for dust extinction, either intergalactic or from the QSO host, and for the Lyman α forest. In the future we want to further discuss properties of the host galaxies, comparing for e.g. the obtained morphological classification with the color, the apparent and absolute magnitudes, and the redshift distributions.

  1. An implantable blood pressure and flow transmitter.

    NASA Technical Reports Server (NTRS)

    Rader, R. D.; Meehan, J. P.; Henriksen, J. K. C.

    1973-01-01

    A miniature totally implantable FM/FM telemetry system has been developed to simultaneously measure blood pressure and blood flow, thus providing an appreciation of the hemodynamics of the circulation to the entire body or to a particular organ. Developed for work with animal subjects, the telemetry system's transmission time is controlled by an RF signal that permits an operating life of several months. Pressure is detected by a miniature intravascular transducer and flow is detected by an extravascular interferometric ultrasonic technique. Both pressure and flow are calibrated prior to implanting. The pressure calibration can be checked after the implanting by cannulation; flow calibration can be verified only at the end of the experiment by determining the voltage output from the implanted sensing system as a function of several measured flow rates. The utility of this device has been established by its use in investigating canine renal circulation during exercise, emotional encounters, administration of drugs, and application of accelerative forces.

  2. Immediate implant post-surgical complications.

    PubMed

    Ibbott, C G; Oles, R D

    1995-03-01

    Immediate surgical implants provide a convenient means of replacing missing teeth without requiring hard tissue reduction of restoration-free potential fixed partial denture abutments. Although the procedure is described as "predictable," complications and failures do occur. This report presents four cases of immediate implant complications and their management, and discusses possible causes of the untoward results. Careful pre-operative planning, adequate surgical technique and post-surgical management, timely and suitable loading, and meticulous hygiene maintenance can serve to minimize implant complications and failures. The prospective immediate implant patient must be provided with sufficient information to allow informed consent to be given. Minimal requirements are a description of the procedures in terms the patient can understand, an explanation of potential risks and complications, and adequate disclosure of information about alternative therapies. PMID:7773849

  3. Extracting parameters from colour-magnitude diagrams

    NASA Astrophysics Data System (ADS)

    Bonatto, C.; Campos, F.; Kepler, S. O.; Bica, E.

    2015-07-01

    We present a simple approach for obtaining robust values of astrophysical parameters from the observed colour-magnitude diagrams (CMDs) of star clusters. The basic inputs are the Hess diagram built with the photometric measurements of a star cluster and a set of isochrones covering wide ranges of age and metallicity. In short, each isochrone is shifted in apparent distance modulus and colour excess until it crosses over the maximum possible Hess density. Repeating this step for all available isochrones leads to the construction of the solution map, in which the optimum values of age and metallicity - as well as foreground/background reddening and distance from the Sun - can be searched for. Controlled tests with simulated CMDs show that the approach is efficient in recovering the input values. We apply the approach to the open clusters M 67, NGC 6791 and NGC 2635, which are characterized by different ages, metallicities and distances from the Sun.

  4. Violence against women: global scope and magnitude.

    PubMed

    Watts, Charlotte; Zimmerman, Cathy

    2002-04-01

    An increasing amount of research is beginning to offer a global overview of the extent of violence against women. In this paper we discuss the magnitude of some of the most common and most severe forms of violence against women: intimate partner violence; sexual abuse by non-intimate partners; trafficking, forced prostitution, exploitation of labour, and debt bondage of women and girls; physical and sexual violence against prostitutes; sex selective abortion, female infanticide, and the deliberate neglect of girls; and rape in war. There are many potential perpetrators, including spouses and partners, parents, other family members, neighbours, and men in positions of power or influence. Most forms of violence are not unique incidents but are ongoing, and can even continue for decades. Because of the sensitivity of the subject, violence is almost universally under-reported. Nevertheless, the prevalence of such violence suggests that globally, millions of women are experiencing violence or living with its consequences. PMID:11955557

  5. Pacemakers and implantable cardioverter defibrillators.

    PubMed

    Allen, M

    2006-09-01

    An increasing number of patients are now treated cardiac pacemakers and implantable cardioverter defibrillators and the technology of these is constantly changing. It is vital to have a good understanding of how they function and what the real risks are. Understanding how the device should work when functioning normally, and the possible effects of electromagnetic interference, is paramount to their safe management in the peri-operative period. Knowing when a device should be disabled or reprogrammed requires careful consideration. Information from the patient's pacemaker clinic should be sought whenever possible and can be invaluable. In addition, the Medicines Healthcare products Regulatory Agency have published the first set of UK guidelines on the management of implantable devices in the presence of surgical diathermy and this will undoubtedly provide a firm foundation on which anaesthetists can base much of their practice. PMID:16922756

  6. Implants in adolescents

    PubMed Central

    Shah, Rohit A.; Mitra, Dipika K.; Rodrigues, Silvia V.; Pathare, Pragalbha N.; Podar, Rajesh S.; Vijayakar, Harshad N.

    2013-01-01

    Implants have gained tremendous popularity as a treatment modality for replacement of missing teeth in adults. There is extensive research present on the use of implants in adults, but there is a dearth of data available on the same in adolescents. The treatment planning and execution of implant placement in adolescents is still in its infancy. This review article is an attempt to bring together available literature. PMID:24174743

  7. Larynx: implants and stents

    PubMed Central

    Sittel, Christian

    2011-01-01

    In the human larynx, implants a primarily used for the correction of glottis insufficiency. In a broader sense laryngeal stents may be considered as implants as well. Laryngeal implants can be differentiated into injectable and solid. The most important representatives of both groups are discussed in detail along with the respective technique of application. Laryngeal stents are primarily used perioperatively. Different types and their use are presented. PMID:22073097

  8. EVALUATION REINFORCER MAGNITUDE AND RATE DEPENDENCY OF RESISTANCE TO CHANGE MECHANIMS

    PubMed Central

    Pinkston, Jonathan W.; Ginsburg, Brett C.; Lamb, R. J.

    2015-01-01

    In many circumstances, reinforcer magnitude appears to modulate the rate-dependent effects of drugs, such that when schedules arrange for relatively larger reinforcer magnitude, rate dependency is attenuated compared to behavior maintained by smaller magnitudes. The current literature on resistance to change suggests that increased reinforcer density strengthens operant behavior, and such strengthening effects appear to extend to the temporal control of behavior. As rate dependency may be understood as a loss of temporal control, the effects of reinforcer magnitude on rate dependency may be due to increased resistance to disruption of temporally controlled behavior. In the present experiments, pigeons earned different magnitudes of grain during signaled components of a multiple fixed-interval schedule. Three drugs, clonidine, haloperidol, and morphine, were examined: all three decreased overall rates of key pecking; however, only the effects of clonidine were attenuated as reinforcer magnitude increased. An analysis of within-interval performance found rate-dependent effects for clonidine and morphine, but those effects were not modulated by reinforcer magnitude. Additionally, we included prefeeding and extinction conditions, standard tests used to measure resistance to change. In general, rate-decreasing effects of prefeeding and extinction were attenuated by increasing reinforcer magnitudes. Rate-dependent analyses of prefeeding showed rate-dependency following those tests, but in no case were these effects modulated by reinforcer magnitude. The results suggest a resistance-to-change interpretation of the effects of reinforcer magnitude on rate dependency is not viable. PMID:25115595

  9. Reinforcer magnitude and rate dependency: evaluation of resistance-to-change mechanisms.

    PubMed

    Pinkston, Jonathan W; Ginsburg, Brett C; Lamb, Richard J

    2014-10-01

    Under many circumstances, reinforcer magnitude appears to modulate the rate-dependent effects of drugs such that when schedules arrange for relatively larger reinforcer magnitudes rate dependency is attenuated compared with behavior maintained by smaller magnitudes. The current literature on resistance to change suggests that increased reinforcer density strengthens operant behavior, and such strengthening effects appear to extend to the temporal control of behavior. As rate dependency may be understood as a loss of temporal control, the effects of reinforcer magnitude on rate dependency may be due to increased resistance to disruption of temporally controlled behavior. In the present experiments, pigeons earned different magnitudes of grain during signaled components of a multiple FI schedule. Three drugs, clonidine, haloperidol, and morphine, were examined. All three decreased overall rates of key pecking; however, only the effects of clonidine were attenuated as reinforcer magnitude increased. An analysis of within-interval performance found rate-dependent effects for clonidine and morphine; however, these effects were not modulated by reinforcer magnitude. In addition, we included prefeeding and extinction conditions, standard tests used to measure resistance to change. In general, rate-decreasing effects of prefeeding and extinction were attenuated by increasing reinforcer magnitudes. Rate-dependent analyses of prefeeding showed rate-dependency following those tests, but in no case were these effects modulated by reinforcer magnitude. The results suggest that a resistance-to-change interpretation of the effects of reinforcer magnitude on rate dependency is not viable. PMID:25115595

  10. Plasma-based ion implantation: a valuable technology for the elaboration of innovative materials and nanostructured thin films

    NASA Astrophysics Data System (ADS)

    Vempaire, D.; Pelletier, J.; Lacoste, A.; Béchu, S.; Sirou, J.; Miraglia, S.; Fruchart, D.

    2005-05-01

    Plasma-based ion implantation (PBII), invented in 1987, can now be considered as a mature technology for thin film modification. After a brief recapitulation of the principle and physics of PBII, its advantages and disadvantages, as compared to conventional ion beam implantation, are listed and discussed. The elaboration of thin films and the modification of their functional properties by PBII have already been achieved in many fields, such as microelectronics (plasma doping/PLAD), biomaterials (surgical implants, bio- and blood-compatible materials), plastics (grafting, surface adhesion) and metallurgy (hard coatings, tribology), to name a few. The major advantages of PBII processing lie, on the one hand, in its flexibility in terms of ion implantation energy (from 0 to 100 keV) and operating conditions (plasma density, collisional or non-collisional ion sheath), and, on the other hand, in the easy transferrability of processes from the laboratory to industry. The possibility of modifying the composition and physical nature of the films, or of drastically changing their physical properties over several orders of magnitude makes this technology very attractive for the elaboration of innovative materials, including metastable materials, and the realization of micro- or nanostructures. A review of the state of the art in these domains is presented and illustrated through a few selected examples. The perspectives opened up by PBII processing, as well as its limitations, are discussed.

  11. [Validity of prediction after standard implant and the implant calculated according to the SRK formula].

    PubMed

    Frisch, E; Chaine, G; Gaudric, A; Coscas, G

    1989-01-01

    The purpose of this study is to appreciate post-operative ametropia in pseudophakic patients (EEC and posterior chamber IOL). Two groups were implanted either with a standard 21 D IOL (group 1) or after calculation of implant power according to the SRK formula (group 2). Results show residual refractive errors over 2 D in 7% of case in group 2 and 22.3% of case in group 1. PMID:2760407

  12. The magnitude distribution of dynamically triggered earthquakes

    NASA Astrophysics Data System (ADS)

    Hernandez, Stephen

    Large dynamic strains carried by seismic waves are known to trigger seismicity far from their source region. It is unknown, however, whether surface waves trigger only small earthquakes, or whether they can also trigger large, societally significant earthquakes. To address this question, we use a mixing model approach in which total seismicity is decomposed into 2 broad subclasses: "triggered" events initiated or advanced by far-field dynamic strains, and "untriggered" spontaneous events consisting of everything else. The b-value of a mixed data set, b MIX, is decomposed into a weighted sum of b-values of its constituent components, bT and bU. For populations of earthquakes subjected to dynamic strain, the fraction of earthquakes that are likely triggered, f T, is estimated via inter-event time ratios and used to invert for bT. The confidence bounds on b T are estimated by multiple inversions of bootstrap resamplings of bMIX and fT. For Californian seismicity, data are consistent with a single-parameter Gutenberg-Richter hypothesis governing the magnitudes of both triggered and untriggered earthquakes. Triggered earthquakes therefore seem just as likely to be societally significant as any other population of earthquakes.

  13. Extended arrays for nonlinear susceptibility magnitude imaging.

    PubMed

    Ficko, Bradley W; Giacometti, Paolo; Diamond, Solomon G

    2015-10-01

    This study implements nonlinear susceptibility magnitude imaging (SMI) with multifrequency intermodulation and phase encoding. An imaging grid was constructed of cylindrical wells of 3.5-mm diameter and 4.2-mm height on a hexagonal two-dimensional 61-voxel pattern with 5-mm spacing. Patterns of sample wells were filled with 40-μl volumes of Fe3O4 starch-coated magnetic nanoparticles (mNPs) with a hydrodynamic diameter of 100 nm and a concentration of 25 mg/ml. The imaging hardware was configured with three excitation coils and three detection coils in anticipation that a larger imaging system will have arrays of excitation and detection coils. Hexagonal and bar patterns of mNP were successfully imaged (R2>0.9) at several orientations. This SMI demonstration extends our prior work to feature a larger coil array, enlarged field-of-view, effective phase encoding scheme, reduced mNP sample size, and more complex imaging patterns to test the feasibility of extending the method beyond the pilot scale. The results presented in this study show that nonlinear SMI holds promise for further development into a practical imaging system for medical applications. PMID:26124044

  14. Demographic factors predict magnitude of conditioned fear.

    PubMed

    Rosenbaum, Blake L; Bui, Eric; Marin, Marie-France; Holt, Daphne J; Lasko, Natasha B; Pitman, Roger K; Orr, Scott P; Milad, Mohammed R

    2015-10-01

    There is substantial variability across individuals in the magnitudes of their skin conductance (SC) responses during the acquisition and extinction of conditioned fear. To manage this variability, subjects may be matched for demographic variables, such as age, gender and education. However, limited data exist addressing how much variability in conditioned SC responses is actually explained by these variables. The present study assessed the influence of age, gender and education on the SC responses of 222 subjects who underwent the same differential conditioning paradigm. The demographic variables were found to predict a small but significant amount of variability in conditioned responding during fear acquisition, but not fear extinction learning or extinction recall. A larger differential change in SC during acquisition was associated with more education. Older participants and women showed smaller differential SC during acquisition. Our findings support the need to consider age, gender and education when studying fear acquisition but not necessarily when examining fear extinction learning and recall. Variability in demographic factors across studies may partially explain the difficulty in reproducing some SC findings. PMID:26151498

  15. Circumferential Calcification of Silicone Implant Misunderstood as a Bony Substitute.

    PubMed

    Lee, Sae Bin; Min, Hyun Jin

    2016-01-01

    Silicone implant is known to be safe and easy to handle, and frequently used in Asian rhinoplasty. Compared with breast implant, complication studies about silicone calcification used in rhinoplasty are very limited. Recently, the authors experienced an interesting patient who underwent revision rhinoplasty in our institution. Based on preoperative images, previously inserted dorsal augmentation material was identified. It was circumferentially enclosed with bony material and hypertrophied bony lesion induced hump on the mid portion of nasal dorsum. During operation, the authors found it was the calcified capsule of silicone implant, and the calcification was surrounding the whole implant material. PMID:26703034

  16. [Immediately loaded MonoType implants in the edentulous mandible].

    PubMed

    Gfeller, F; Zitzmann, N U; Lambrecht, J Thomas

    2011-01-01

    Results of immediately loaded implants are presented. 34 patients with 136 interforaminal MonoType implants (Straumann,Basel, Switzerland) were included in the study. The bar retention was manufactured fter the operation, inserted and covered with a hybrid prosthesis. 28 patients showed up for the follow-up study, the average time range was three years. Five implants were rated as failures, the cumulative six-year success rate being 94%. Interforaminal immediately loaded MonoType implants in edentulous patients showed very good results, comparable to similar studies with different systems. PMID:21560796

  17. Chinese tonal language rehabilitation following cochlear implantation in children.

    PubMed

    Wei, W I; Wong, R; Hui, Y; Au, D K; Wong, B Y; Ho, W K; Tsang, A; Kung, P; Chung, E

    2000-03-01

    Cantonese language rehabilitation in 28 prelingually deaf children who underwent cochlear implantation was evaluated. All patients were implanted with multichannel devices and the operations went smoothly. They all had improved scores on audiological assessments and speech perception tests. The speech evaluation tests included the recognition of sounds, vowels, consonants and tone. Sentence recognition and story comprehension were both improved after training for 2 years. Cochlear implantation is a useful measure for the speech rehabilitation of prelingually profound deaf children when hearing aids are of no benefit. The multichannel implant device is of clinical significance in the rehabilitation of those patients using tonal language. PMID:11603776

  18. Electrochemical Evaluation of Nanocrystalline Diamond Thin Films on Ti-6Al-4V Implant Alloy

    NASA Astrophysics Data System (ADS)

    Fries, Marc; Venugopalan, Ramakrishna; Vohra, Yogesh

    2002-03-01

    Some 186,000 hip replacement surgeries are peformed every year in the United States alone. About 10surgeries are revision operations to replace an implant that has most likely failed through mechanical-electrochemical interactions resulting in implant wear. The ability to enhance the resistance to such mechanical-electrochemical interaction and thereby reduce wear could result in significantly increased device lifespan. Nanocrystalline diamond (NCD) thin films were deposited on Ti-6Al-4V disk samples (processed per ASTM F86 standard for medical implant surface conditions) using microwave plasma chemical vapor deposition (MPCVD). As a first step, these samples (n=3/test per group) were subjected to electrochemical evaluation in inorganic neutral salt solution at 37 C. The electrochemical evaluation involved both impedence spectroscopy (per ASTM G106) and polarization testing (per ASTM G5). The impedence spectroscopy data indicated a significantly higher charge transfer resistance at the interface due to the protective NCD as compared to the bare or uncoated substrate. The polarization test data confirmed that this increased charge transfer resistance resulted in a decreased current density measurement. This decreased current density measurement resulted in an order of magnitude lower calculated static corrosion rate from the NCD coated samples as opposed to the uncoated controls. Future studies will focus on investigations that will facilitate transfer of these static electrochemical resistance results to a more relevant mechanical-electrochemical interaction milieu.

  19. Smoking and dental implants

    PubMed Central

    Kasat, V.; Ladda, R.

    2012-01-01

    Smoking is a prevalent behaviour in the population. The aim of this review is to bring to light the effects of smoking on dental implants. These facts will assist dental professionals when implants are planned in tobacco users. A search of “PubMed” was made with the key words “dental implant,” “nicotine,” “smoking,” “tobacco,” and “osseointegration.” Also, publications on tobacco control by the Government of India were considered. For review, only those articles published from 1988 onward in English language were selected. Smoking has its influence on general as well as oral health of an individual. Tobacco negatively affects the outcome of almost all therapeutic procedures performed in the oral cavity. The failure rate of implant osseointegration is considerably higher among smokers, and maintenance of oral hygiene around the implants and the risk of peri-implantitis are adversely affected by smoking. To increase implant survival in smokers, various protocols have been recommended. Although osseointegrated dental implants have become the state of the art for tooth replacement, they are not without limitations or complications. In this litigious era, it is extremely important that the practitioner clearly understands and is able and willing to convey the spectrum of possible complications and their frequency to the patients. PMID:24478965

  20. Implantable, Ingestible Electronic Thermometer

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard

    1987-01-01

    Small quartz-crystal-controlled oscillator swallowed or surgically implanted provides continuous monitoring of patient's internal temperature. Receiver placed near patient measures oscillator frequency, and temperature inferred from previously determined variation of frequency with temperature. Frequency of crystal-controlled oscillator varies with temperature. Circuit made very small and implanted or ingested to measure internal body temperature.

  1. Synthetic facial implants.

    PubMed

    Quatela, Vito C; Chow, Jen

    2008-02-01

    This article presents a range of synthetic implant materials for use in facial plastic surgery. The authors discuss alternatives to autogenous tissue transfer in terms of biocompatibility, technique, complications, controversies, and cautions. The reader is presented information about a range of synthetic implant materials such as silicone, polyester fiber, polyamide mesh, metal, polyethylene, polyacrylamide gel, hydroxyapatite, polylactic acid, collagen, and others. PMID:18063244

  2. Implantable CMOS Biomedical Devices

    PubMed Central

    Ohta, Jun; Tokuda, Takashi; Sasagawa, Kiyotaka; Noda, Toshihiko

    2009-01-01

    The results of recent research on our implantable CMOS biomedical devices are reviewed. Topics include retinal prosthesis devices and deep-brain implantation devices for small animals. Fundamental device structures and characteristics as well as in vivo experiments are presented. PMID:22291554

  3. Batteryless implanted echosonometer

    NASA Technical Reports Server (NTRS)

    Kojima, G. K.

    1977-01-01

    Miniature ultrasonic echosonometer implanted within laboratory animals obtains energy from RF power oscillator that is electronically transduced via induction loop to power receiving loop located just under animal's skin. Method of powering device offers significant advantages over those in which battery is part of implanted package.

  4. Gold bead implants.

    PubMed

    Durkes, T E

    1992-03-01

    Gold bead implantation is an experimental area of study in the acupuncture field dealing with chronic diseases. Special acupuncture techniques are required to implant the gold beads successfully in the proper location. Gold beads are used to treat degenerative joint disease, osteochondritis, osteochondritis dessicans, ventral spondylosis, and seizures. PMID:1581658

  5. Percutaneous and skeletal biocarbon implants

    NASA Technical Reports Server (NTRS)

    Mooney, V.

    1977-01-01

    Review of carbon implants developed by NASA discussed four different types of implants and subsequent improvements. Improvements could be of specific interest to rehabilitation centers and similar organizations.

  6. Number of implants for mandibular implant overdentures: a systematic review

    PubMed Central

    Lee, Jeong-Yol; Kim, Ha-Young; Bryant, S. Ross

    2012-01-01

    PURPOSE The aim of this systematic review is to address treatment outcomes of Mandibular implant overdentures relative to implant survival rate, maintenance and complications, and patient satisfaction. MATERIALS AND METHODS A systematic literature search was conducted by a PubMed search strategy and hand-searching of relevant journals from included studies. Randomized Clinical Trials (RCT) and comparative clinical trial studies on mandibular implant overdentures until August, 2010 were selected. Eleven studies from 1098 studies were finally selected and data were analyzed relative to number of implants. RESULTS Six studies presented the data of the implant survival rate which ranged from 95% to 100% for 2 and 4 implant group and from 81.8% to 96.1% for 1 and 2 implant group. One study, which statistically compared implant survival rate showed no significant differences relative to the number of implants. The most common type of prosthetic maintenance and complications were replacement or reattaching of loose clips for 2 and 4 implant group, and denture repair due to the fracture around an implant for 1 and 2 implant groups. Most studies showed no significant differences in the rate of prosthetic maintenance and complication, and patient satisfaction regardless the number of implants. CONCLUSION The implant survival rate of mandibular overdentures is high regardless of the number of implants. Denture maintenance is likely not inflenced substantially by the number of implants and patient satisfaction is typically high again regardless os the number of implants. PMID:23236572

  7. Graphene for Biomedical Implants

    NASA Astrophysics Data System (ADS)

    Moore, Thomas; Podila, Ramakrishna; Alexis, Frank; Rao, Apparao; Clemson Bioengineering Team; Clemson Physics Team

    2013-03-01

    In this study, we used graphene, a one-atom thick sheet of carbon atoms, to modify the surfaces of existing implant materials to enhance both bio- and hemo-compatibility. This novel effort meets all functional criteria for a biomedical implant coating as it is chemically inert, atomically smooth and highly durable, with the potential for greatly enhancing the effectiveness of such implants. Specifically, graphene coatings on nitinol, a widely used implant and stent material, showed that graphene coated nitinol (Gr-NiTi) supports excellent smooth muscle and endothelial cell growth leading to better cell proliferation. We further determined that the serum albumin adsorption on Gr-NiTi is greater than that of fibrinogen, an important and well understood criterion for promoting a lower thrombosis rate. These hemo-and biocompatible properties and associated charge transfer mechanisms, along with high strength, chemical inertness and durability give graphene an edge over most antithrombogenic coatings for biomedical implants and devices.

  8. Cochlear implants in children.

    PubMed

    Young, N M

    1994-04-01

    Children with such profound deafness that they are not helped by hearing aids are now candidates for cochlear implantation. This technology permits us to provide these children with a significant degree of useful hearing. The degree of improvement in speech perception and spoken language in pediatric cochlear implant recipients varies. However, the younger the children and the less time they have been completely deprived of auditory stimuli, the more likely they are to make significant progress. The evaluation of the deaf child for implantation is best done by a multidisciplinary team who understands the needs of hearing-impaired children and who can work with the family, the child, and classroom teachers, as well as other school professionals. The decision to proceed with cochlear implantation in a child is one that requires long-term commitment on the part of the family and the cochlear implant team. PMID:8039409

  9. [Implantable medical devices].

    PubMed

    Crickx, B; Arrault, X

    2008-01-01

    Medical devices have been individualized to include a category of implantable medical devices, "designed to be totally implanted in the human body or to replace an epithelial surface or a surface of the eye, through surgery, and remain in place after the intervention" (directive 93/42/CEE and decree of 20 April 206). Each implantable medical device has a common name and a commercial name for precise identification of the model (type/references). The users' service and the implanting physician should be clearly identified. There are a number of rules concerning health traceability to rapidly identify patients exposed to risks in which the implantable medical devices of a particular batch or series were used and to monitor the consequences. The traceability data should be preserved 10 years and the patient's medical file for 20 years. PMID:18442666

  10. Model for ion-implantation-induced improvements of photoferroelectric imaging in lead lanthanum zirconate titanate ceramics

    SciTech Connect

    Peercy, P.S.; Land, C.E.

    1980-11-01

    Studies of photoferroelectric image storage in H-, He-, and, more recently, Ar-implanted /(PLZT) lead lanthanum zirconate titanate reveal that the photosensitivity can be significantly increased by ion implantation into the image storage surface. For example, the photosensitivity after implantation with 5 x 10/sup 14/ 500-keV Ar/cm/sup 2/ is increased by about three orders of magnitude over that of unimplanted PLZT. The increase in photosensitivity results from a decrease in dark conductivity and changes in the photoconductivity of the implanted layer. We present a phenomenological model which describes the photosensitivity enhancement obtained by ion implantation. This model takes into account both light- and ion- implantation-induced changes in conductivity and gives quantitative agreement with the measured changes in the coercive voltage with near-UV light intensity for ion-implantated PLZT.

  11. Nonlinear Susceptibility Magnitude Imaging of Magnetic Nanoparticles

    PubMed Central

    Ficko, Bradley W.; Giacometti, Paolo; Diamond, Solomon G.

    2014-01-01

    This study demonstrates a method for improving the resolution of susceptibility magnitude imaging (SMI) using spatial information that arises from the nonlinear magnetization characteristics of magnetic nanoparticles (mNPs). In this proof-of-concept study of nonlinear SMI, a pair of drive coils and several permanent magnets generate applied magnetic fields and a coil is used as a magnetic field sensor. Sinusoidal alternating current (AC) in the drive coils results in linear mNP magnetization responses at primary frequencies, and nonlinear responses at harmonic frequencies and intermodulation frequencies. The spatial information content of the nonlinear responses is evaluated by reconstructing tomographic images with sequentially increasing voxel counts using the combined linear and nonlinear data. Using the linear data alone it is not possible to accurately reconstruct more than 2 voxels with a pair of drive coils and a single sensor. However, nonlinear SMI is found to accurately reconstruct 12 voxels (R2 = 0.99, CNR = 84.9) using the same physical configuration. Several time-multiplexing methods are then explored to determine if additional spatial information can be obtained by varying the amplitude, phase and frequency of the applied magnetic fields from the two drive coils. Asynchronous phase modulation, amplitude modulation, intermodulation phase modulation, and frequency modulation all resulted in accurate reconstruction of 6 voxels (R2 > 0.9) indicating that time multiplexing is a valid approach to further increase the resolution of nonlinear SMI. The spatial information content of nonlinear mNP responses and the potential for resolution enhancement with time multiplexing demonstrate the concept and advantages of nonlinear SMI. PMID:25505816

  12. Dental Implant Systems

    PubMed Central

    Oshida, Yoshiki; Tuna, Elif B.; Aktören, Oya; Gençay, Koray

    2010-01-01

    Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s) in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities. PMID:20480036

  13. Aerogel Antennas Communications Study Using Error Vector Magnitude Measurements

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Mueller, Carl H.; Meador, Mary Ann B.

    2014-01-01

    This presentation discusses an aerogel antennas communication study using error vector magnitude (EVM) measurements. The study was performed using 2x4 element polyimide (PI) aerogel-based phased arrays designed for operation at 5 GHz as transmit (Tx) and receive (Rx) antennas separated by a line of sight (LOS) distance of 8.5 meters. The results of the EVM measurements demonstrate that polyimide aerogel antennas work appropriately to support digital communication links with typically used modulation schemes such as QPSK and 4 DQPSK. As such, PI aerogel antennas with higher gain, larger bandwidth and lower mass than typically used microwave laminates could be suitable to enable aerospace-to- ground communication links with enough channel capacity to support voice, data and video links from CubeSats, unmanned air vehicles (UAV), and commercial aircraft.

  14. Aerogel Antennas Communications Study Using Error Vector Magnitude Measurements

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Mueller, Carl H.; Meador, Mary Ann B.

    2014-01-01

    This paper discusses an aerogel antennas communication study using error vector magnitude (EVM) measurements. The study was performed using 4x2 element polyimide (PI) aerogel-based phased arrays designed for operation at 5 GHz as transmit (Tx) and receive (Rx) antennas separated by a line of sight (LOS) distance of 8.5 meters. The results of the EVM measurements demonstrate that polyimide aerogel antennas work appropriately to support digital communication links with typically used modulation schemes such as QPSK and pi/4 DQPSK. As such, PI aerogel antennas with higher gain, larger bandwidth and lower mass than typically used microwave laminates could be suitable to enable aerospace-to-ground communication links with enough channel capacity to support voice, data and video links from cubesats, unmanned air vehicles (UAV), and commercial aircraft.

  15. Automatic computation of moment magnitudes for small earthquakes and the scaling of local to moment magnitude

    NASA Astrophysics Data System (ADS)

    Edwards, Benjamin; Allmann, Bettina; Fäh, Donat; Clinton, John

    2010-10-01

    Moment magnitudes (MW) are computed for small and moderate earthquakes using a spectral fitting method. 40 of the resulting values are compared with those from broadband moment tensor solutions and found to match with negligible offset and scatter for available MW values of between 2.8 and 5.0. Using the presented method, MW are computed for 679 earthquakes in Switzerland with a minimum ML = 1.3. A combined bootstrap and orthogonal L1 minimization is then used to produce a scaling relation between ML and MW. The scaling relation has a polynomial form and is shown to reduce the dependence of the predicted MW residual on magnitude relative to an existing linear scaling relation. The computation of MW using the presented spectral technique is fully automated at the Swiss Seismological Service, providing real-time solutions within 10 minutes of an event through a web-based XML database. The scaling between ML and MW is explored using synthetic data computed with a stochastic simulation method. It is shown that the scaling relation can be explained by the interaction of attenuation, the stress-drop and the Wood-Anderson filter. For instance, it is shown that the stress-drop controls the saturation of the ML scale, with low-stress drops (e.g. 0.1-1.0 MPa) leading to saturation at magnitudes as low as ML = 4.

  16. Reflections on Rodent Implantation.

    PubMed

    Cha, Jeeyeon M; Dey, Sudhansu K

    2015-01-01

    Embryo implantation is a complex process involving endocrine, paracrine, autocrine, and juxtacrine modulators that span cell-cell and cell-matrix interactions. The quality of implantation is predictive for pregnancy success. Earlier observational studies formed the basis for genetic and molecular approaches that ensued with emerging technological advances. However, the precise sequence and details of the molecular interactions involved have yet to be defined. This review reflects briefly on aspects of our current understanding of rodent implantation as a tribute to Roger Short's lifelong contributions to the field of reproductive physiology. PMID:26450495

  17. [Implantable hearing aids].

    PubMed

    Luers, J C; Beutner, D; Hüttenbrink, K-B

    2011-10-01

    Strictly speaking, implantable hearing aids are technical systems that process audiological signals and convey these by direct mechanical stimulation of the ossicular chain or cochlea. They have certain benefits over conventional hearing aids in terms of wearing comfort and general acceptance. As current studies lack convincing audiological results, the indications for implantable hearing aids are primarily of medical or cosmetic nature. To date, three systems are available in Germany: Vibrant Soundbridge®, Carina®, and Esteem®. Because the performance of the different implantable and nonimplantable hearing systems together with various surgical procedures are currently undergoing major changes, audiological indications may also develop in the future. PMID:21956678

  18. Transcatheter aortic valve implantation

    PubMed Central

    Oliemy, Ahmed

    2014-01-01

    Transcatheter aortic valve implantation was developed to offer a therapeutic solution to patients with severe symptomatic aortic stenosis who are not candidates for conventional aortic valve replacement. The improvement in transcatheter aortic valve implantation outcomes is still of concern in the areas of stroke, vascular injury, heart block, paravalvular regurgitation and valve durability. Concomitantly, the progress, both technical and in terms of material advances of transcatheter valve systems, as well as in patient selection, renders transcatheter aortic valve implantation an increasingly viable treatment for more and more patients with structural heart disease. PMID:25374670

  19. Photosensitivity and imaging characteristics of ion-implanted PLZT ceramics

    SciTech Connect

    Land, C.E.

    1985-01-01

    We reported in previous papers that both the near-uv and the visible photosensitivities of ferroelectric-phase PLZT (lead lanthanum zirconate titanate) ceramics are increased by as much as four orders of magnitude by ion implantation or a combination of thermal diffusion of Al and ion implantation. New results are presented here on high-energy (1 MeV) implants of Al and Ni and coimplants of Al + Ne and Ni + Ne, and these results are compared with earlier 500 keV implants of Al and Cr and coimplants of Al + Ne and Cr + Ne as surface modification techniques for increasing the visible photosensitivity of PLZT. The important role of grain size in determining optimum contrast and resolution of stored optical information is described in terms of new experimental results.

  20. Plasma immersion ion implantation for reducing metal ion release

    SciTech Connect

    Diaz, C.; Garcia, J. A.; Maendl, S.; Pereiro, R.; Fernandez, B.; Rodriguez, R. J.

    2012-11-06

    Plasma immersion ion implantation of Nitrogen and Oxygen on CoCrMo alloys was carried out to improve the tribological and corrosion behaviors of these biomedical alloys. In order to optimize the implantation results we were carried experiments at different temperatures. Tribocorrosion tests in bovine serum were used to measure Co, Cr and Mo releasing by using Inductively Coupled Plasma Mass Spectrometry analysis after tests. Also, X-ray Diffraction analysis were employed in order to explain any obtained difference in wear rate and corrosion tests. Wear tests reveals important decreases in rate of more than one order of magnitude for the best treatment. Moreover decreases in metal release were found for all the implanted samples, preserving the same corrosion resistance of the unimplanted samples. Finally this paper gathers an analysis, in terms of implantation parameters and achieved properties for industrial implementation of these treatments.

  1. Al-O interactions in ion-implanted crystalline silicon

    NASA Astrophysics Data System (ADS)

    Galvagno, G.; La Ferla, A.; Spinella, C.; Priolo, F.; Raineri, V.; Torrisi, Lucio; Rimini, E.; Carnera, A.; Gasparotto, A.

    1994-08-01

    The formation and dissolution of Si-O-Al precipitates have been investigated in Czochralski silicon wafers implanted with 6 MeV Al ions and thermally processed. The data have been compared to the O precipitation in samples implanted with 6 MeV Si or P ions. The amount of precipitated O atoms is about one order of magnitude higher for Al than for Si or P implanted samples. Moreover, a strong gettering of the Al atoms by the silicon dioxide precipitates has been observed. The precipitate evolution has been studied for different annealing times and temperatures. The oxygen precipitation has been simulated by the classical theory of nucleation and growth, with the introduction of new factors that take into account the implant damage distribution, the agglomeration of point defects during the initial stages of the annealing and the oxygen outdiffusion from the sample surface.

  2. Electrochemical Disinfection of Dental Implants – a Proof of Concept

    PubMed Central

    Mohn, Dirk; Zehnder, Matthias; Stark, Wendelin J.; Imfeld, Thomas

    2011-01-01

    Background Peri-implantitis has gained significant clinical attention in recent years. This disease is an inflammatory reaction to microorganisms around dental implants. Due to the limited accessibility, non-invasive antimicrobial strategies are of high interest. An unexpected approach to implant disinfection may evolve from electrolysis. Given the electrical conductivity of titanium implants, alkalinity or active oxidants can be generated in body fluids. We investigated the use of dental titanium implants as electrodes for the local generation of disinfectants. Our hypothesis was that electrolysis can reduce viable counts of adhering bacteria, and that this reduction should be greater if active oxidative species are generated. Methodology/Principal Findings As model systems, dental implants, covered with a mono-species biofilm of Escherichia coli C43, were placed in photographic gelatin prepared with physiological saline. Implants were treated by a continuous current of 0 - 10 mA for 15 minutes. The reduction of viable counts was investigated on cathodes and anodes. In separate experiments, the local change in pH was visualized using color indicators embedded in the gelatin. Oxidative species were qualitatively detected by potassium iodide-starch paper. The in situ generated alkaline environment around cathodic implants caused a reduction of up to 2 orders of magnitude in viable E. coli counts. On anodic implants, in contrast to cathodic counterparts, oxidative species were detected. Here, a current of merely 7.5 mA caused complete kill of the bacteria. Conclusions/Significance This laboratory study shows that electrochemical treatment may provide access to a new way to decontaminate dental implants in situ. PMID:21264247

  3. The evolution of embryo implantation.

    PubMed

    McGowen, Michael R; Erez, Offer; Romero, Roberto; Wildman, Derek E

    2014-01-01

    Embryo implantation varies widely in placental mammals. We review this variation in mammals with a special focus on two features: the depth of implantation and embryonic diapause. We discuss the two major types of implantation depth, superficial and interstitial, and map this character on a well-resolved molecular phylogenetic tree of placental mammals. We infer that relatively deep interstitial implantation has independently evolved at least eight times within placental mammals. Moreover, the superficial type of implantation represents the ancestral state for placental mammals. In addition, we review the genes involved in various phases of implantation, and suggest a future direction in investigating the molecular evolution of implantation-related genes. PMID:25023681

  4. 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

  5. [Silicone breast implants].

    PubMed

    Nielsen, M; Brandt, B; Breiting, V B; Christensen, L H; Thomsen, J L

    1989-12-18

    A brief review of the use of silicone breast implants, their structure, methods of implantation and complications is presented. Acute complications are rare, being mainly infection and hematoma. Long-term complications, on the contrary, are common, consisting mainly of capsular contracture around the prosthesis with subsequent pain and deformation of the breast. More rarely silicone granulomas form, and prosthesis rupture or herniation occurs. The importance of silicone leakage for these complications is discussed separately as well as the treatment of and prevention of capsular contracture and demonstration of silicone in tissue. A critical attitude towards the use of silicone breast implants, when these are used for purely cosmetic purposes, is recommended at present. New improved types of silicone breast implants are currently being tested clinically. PMID:2692262

  6. Peri-Implant Diseases

    MedlinePlus

    ... and flossing and regular check-ups from a dental professional. Other risks factors for developing peri-implant disease include previous periodontal disease diagnosis, poor plaque control, smoking , and diabetes . It is essential to routinely ...

  7. Biocompatibility of surgical implants

    NASA Technical Reports Server (NTRS)

    Kaelble, D. H.

    1979-01-01

    Method of selecting biocompatible materials for surgical implants uses fracture mechanic relationships and surface energies of candidate materials in presence of blood plasma. Technique has been used to characterize 190 materials by parameters that reflect their biocompatibility.

  8. Risks of Breast Implants

    MedlinePlus

    ... larger and longer than these conducted so far. Breastfeeding Some women who undergo breast augmentation can successfully ... breast implant silicone shell into breast milk during breastfeeding. Although there are currently no established methods for ...

  9. Clinically based implant selection.

    PubMed

    Fugazzotto, P A

    1999-01-01

    A hierarchy of implant selection is presented, based on overcoming specific clinical challenges in a variety of situations, including maximization of the esthetic, comfort, and functional potentials of therapy. PMID:10709488

  10. Breast reconstruction - implants

    MedlinePlus

    ... stages, or surgeries. During the first stage, a tissue expander is used. An implant is placed during the ... a pouch under your chest muscle. A small tissue expander is placed in the pouch. The expander is ...

  11. Superelastic Orthopedic Implant Coatings

    NASA Astrophysics Data System (ADS)

    Fournier, Eric; Devaney, Robert; Palmer, Matthew; Kramer, Joshua; El Khaja, Ragheb; Fonte, Matthew

    2014-07-01

    The demand for hip and knee replacement surgery is substantial and growing. Unfortunately, most joint replacement surgeries will fail within 10-25 years, thereby requiring an arduous, painful, and expensive revision surgery. To address this issue, a novel orthopedic implant coating material ("eXalt") has been developed. eXalt is comprised of super elastic nitinol wire that is knit into a three-dimensional spacer fabric structure. eXalt expands in vivo to conform to the implantation site and is porous to allow for bone ingrowth. The safety and efficacy of eXalt were evaluated through structural analysis, mechanical testing, and a rabbit implantation model. The results demonstrate that eXalt meets or exceeds the performance of current coating technologies with reduced micromotion, improved osseointegration, and stronger implant fixation in vivo.

  12. Implantable microscale neural interfaces.

    PubMed

    Cheung, Karen C

    2007-12-01

    Implantable neural microsystems provide an interface to the nervous system, giving cellular resolution to physiological processes unattainable today with non-invasive methods. Such implantable microelectrode arrays are being developed to simultaneously sample signals at many points in the tissue, providing insight into processes such as movement control, memory formation, and perception. These electrode arrays have been microfabricated on a variety of substrates, including silicon, using both surface and bulk micromachining techniques, and more recently, polymers. Current approaches to achieving a stable long-term tissue interface focus on engineering the surface properties of the implant, including coatings that discourage protein adsorption or release bioactive molecules. The implementation of a wireless interface requires consideration of the necessary data flow, amplification, signal processing, and packaging. In future, the realization of a fully implantable neural microsystem will contribute to both diagnostic and therapeutic applications, such as a neuroprosthetic interface to restore motor functions in paralyzed patients. PMID:17252207

  13. Implant treatment planning: endodontic considerations.

    PubMed

    Simonian, Krikor; Frydman, Alon; Verdugo, Fernando; Roges, Rafael; Kar, Kian

    2014-12-01

    Implants are a predictable and effective method for replacing missing teeth. Some clinicians have advocated extraction and replacement of compromised but treatable teeth on the assumption that implants will outperform endodontically and/or periodontally treated teeth. However, evidence shows that conventional therapy is as effective as implant treatment. With data on implants developing complications long term and a lack of predictable treatment for peri-implantitis, retaining and restoring the natural dentition should be the first choice when possible. PMID:25928961

  14. Ion implantation at elevated temperatures

    SciTech Connect

    Lam, N.Q.; Leaf, G.K.

    1985-11-01

    A kinetic model has been developed to investigate the synergistic effects of radiation-enhanced diffusion, radiation-induced segregation and preferential sputtering on the spatial redistribution of implanted solutes during implantation at elevated temperatures. Sample calculations were performed for Al and Si ions implanted into Ni. With the present model, the influence of various implantation parameters on the evolution of implant concentration profiles could be examined in detail.

  15. Dental implants inserted in native bone: Cases series analyses

    PubMed Central

    Guidi, Riccardo; Viscioni, Alessandro; Dattola, Frencesco; Carinci, Francesco

    2012-01-01

    Background: The concept of osseointegration, i.e., the direct anchorage of endosseous implants made of commercially pure or titanium alloy to the bone caused a breakthrough in oral rehabilitation. The identification of factors for long-term survival and success rate are the main goal of the recent literature. Several variables can influence the final result, and in general they are grouped in surgery-, host-, implant-, and occlusion-related factors. Materials and Methods: A retrospective analysis on a large series of dental implants was performed to detect those variables influencing the clinical outcome. In the period between January 2007 and December 2009, 157 patients were operated. A total of 429 implants were inserted. Dental implants are reliable devices to be used in oral rehabilitation. Results: Globally, very few implants were lost at the end of the follow-up period. Slight but significant differences existed among different implants types with regard to peri-implant bone resorption. Conclusion: A better clinical outcome was revealed for Sweden and Martina global implant. PMID:23814579

  16. Influence of Time and Space Correlations on Earthquake Magnitude

    SciTech Connect

    Lippiello, E.; Arcangelis, L. de; Godano, C.

    2008-01-25

    A crucial point in the debate on the feasibility of earthquake predictions is the dependence of an earthquake magnitude from past seismicity. Indeed, while clustering in time and space is widely accepted, much more questionable is the existence of magnitude correlations. The standard approach generally assumes that magnitudes are independent and therefore in principle unpredictable. Here we show the existence of clustering in magnitude: earthquakes occur with higher probability close in time, space, and magnitude to previous events. More precisely, the next earthquake tends to have a magnitude similar but smaller than the previous one. A dynamical scaling relation between magnitude, time, and space distances reproduces the complex pattern of magnitude, spatial, and temporal correlations observed in experimental seismic catalogs.

  17. Exploring the relationship between the magnitudes of seismic events

    NASA Astrophysics Data System (ADS)

    Spassiani, Ilaria; Sebastiani, Giovanni

    2016-02-01

    The distribution of the magnitudes of seismic events is generally assumed to be independent on past seismicity. However, by considering events in causal relation, for example, mother-daughter, it seems natural to assume that the magnitude of a daughter event is conditionally dependent on one of the corresponding mother events. In order to find experimental evidence supporting this hypothesis, we analyze different catalogs, both real and simulated, in two different ways. From each catalog, we obtain the law of the magnitude of the triggered events by kernel density. The results obtained show that the distribution density of the magnitude of the triggered events varies with the magnitude of their corresponding mother events. As the intuition suggests, an increase of the magnitude of the mother events induces an increase of the probability of having "high" values of the magnitude of the triggered events. In addition, we see a statistically significant increasing linear dependence of the magnitude means.

  18. Functional shape of the earthquake frequency-magnitude distribution and completeness magnitude

    NASA Astrophysics Data System (ADS)

    Mignan, A.

    2012-08-01

    We investigated the functional shape of the earthquake frequency-magnitude distribution (FMD) to identify its dependence on the completeness magnitude Mc. The FMD takes the form N(m) ∝ exp(-βm)q(m) where N(m) is the event number, m the magnitude, exp(-βm) the Gutenberg-Richter law and q(m) a detection function. q(m) is commonly defined as the cumulative Normal distribution to describe the gradual curvature of bulk FMDs. Recent results however suggest that this gradual curvature is due to Mc heterogeneities, meaning that the functional shape of the elemental FMD has yet to be described. We propose a detection function of the form q(m) = exp(κ(m - Mc)) for m < Mc and q(m) = 1 for m ≥ Mc, which leads to an FMD of angular shape. The two FMD models are compared in earthquake catalogs from Southern California and Nevada and in synthetic catalogs. We show that the angular FMD model better describes the elemental FMD and that the sum of elemental angular FMDs leads to the gradually curved bulk FMD. We propose an FMD shape ontology consisting of 5 categories depending on the Mc spatial distribution, from Mc constant to Mc highly heterogeneous: (I) Angular FMD, (II) Intermediary FMD, (III) Intermediary FMD with multiple maxima, (IV) Gradually curved FMD and (V) Gradually curved FMD with multiple maxima. We also demonstrate that the gradually curved FMD model overestimates Mc. This study provides new insights into earthquake detectability properties by using seismicity as a proxy and the means to accurately estimate Mc in any given volume.

  19. Electrically active sulfur-defect complexes in sulfur implanted diamond

    NASA Astrophysics Data System (ADS)

    Kalish, R.; Uzan-Saguy, C.; Walker, R.; Prawer, S.

    2003-09-01

    Single crystal type IIa <100> diamonds were implanted with sulfur, phosphorus, and argon ions under different implantation and annealing conditions. Shallow (sub-MeV) as well as deep (MeV) implantations into samples held at low (liquid nitrogen) ambient (room temperature) and high (400 °C) temperatures were employed. The implanted samples were subjected to postimplantation annealing up to 1000 °C. Following each processing step the samples were subjected to (i) Raman spectroscopy, in order to investigate the implantation related residual defects, and (ii) electrical (resistivity and sometimes Hall effect) measurements as function of temperature. The correlation between the results of these structural and electrical measurements and the comparison of results obtained under identical processing conditions for possible n-type dopant ion-implantations (S and P) and inert (Ar) ion-implantations, as controls, leads to the following conclusions: (a) Sulfur implanted samples always exhibit at least one order of magnitude higher conductivity than Ar control implanted samples. The activation energy associated with the S related conductivity is 0.32-0.37 eV whereas that of the Ar control is 0.5 to 0.6 eV. Hall effect shows, for selected cases, n-type conductivity with low carrier concentration and mobility. (b) Although the presence of some residual defects (mainly split interstitials) seems to accompany the appearance of the S related electrical activity, the level of residual damage in the S implanted samples is always less than that of the Ar control. (c) The electrical effects due to the implantation of S vanish upon annealing at temperatures in access of 800 °C. (d) No significant difference in the electrical properties between P and control Ar implantations are evident. It is concluded that a sulfur-defect related complex, which decomposes at T>800 °C, is responsible for the electrical effects in S implanted diamond. The presence of B contamination which has

  20. Biomaterials in cochlear implants

    PubMed Central

    Stöver, Timo; Lenarz, Thomas

    2011-01-01

    The cochlear implant (CI) represents, for almost 25 years now, the gold standard in the treatment of children born deaf and for postlingually deafened adults. These devices thus constitute the greatest success story in the field of ‘neurobionic’ prostheses. Their (now routine) fitting in adults, and especially in young children and even babies, places exacting demands on these implants, particularly with regard to the biocompatibility of a CI’s surface components. Furthermore, certain parts of the implant face considerable mechanical challenges, such as the need for the electrode array to be flexible and resistant to breakage, and for the implant casing to be able to withstand external forces. As these implants are in the immediate vicinity of the middle-ear mucosa and of the junction to the perilymph of the cochlea, the risk exists – at least in principle – that bacteria may spread along the electrode array into the cochlea. The wide-ranging requirements made of the CI in terms of biocompatibility and the electrode mechanism mean that there is still further scope – despite the fact that CIs are already technically highly sophisticated – for ongoing improvements to the properties of these implants and their constituent materials, thus enhancing the effectiveness of these devices. This paper will therefore discuss fundamental material aspects of CIs as well as the potential for their future development. PMID:22073103

  1. [Implantable materials (author's transl)].

    PubMed

    Schaldach, M

    1975-11-01

    There is a steadily increasing importance of implants used as substitutions for body functions which have been impaired due to disease, natural abrasion or accident. With the present state of the art, the limitations for the application of surgical substitutions are due to insufficient properties of biomaterials with regard to specific applications as well as to deficiencies in design and function of the implants used. The basis for the improvement and new development of implants is therefore a functionally adequate design in which the specific properties of the material are taken into account with regard to the individual requirements of the implantation site. For orthopedic implants, materials have to be developed which are to a large extent corrosion and degradation resistant, and withstand high mechanical stress. For implants in the cardiovascular system, compatibility with blood is most significant. Present research in this field is concentrated on efforts to improve the thromboresistivity of conventional polymers by different kinds of surface treatments. One possibility is to influence actively the electrochemical interactions between material and blood components, e.g. by the use of redox catalysts. PMID:1107653

  2. Improvement of device isolation using field implantation for GaN MOSFETs

    NASA Astrophysics Data System (ADS)

    Jiang, Ying; Wang, Qingpeng; Zhang, Fuzhe; Li, Liuan; Shinkai, Satoko; Wang, Dejun; Ao, Jin-Ping

    2016-03-01

    Gallium nitride (GaN) metal-oxide-semiconductor field-effect transistors (MOSFETs) with boron field implantation isolation and mesa isolation were fabricated and characterized. The process of boron field implantation was altered and subsequently conducted after performing high-temperature ohmic annealing and gate oxide thermal treatment. Implanted regions with high resistivity were achieved. The circular MOSFET fabricated in the implanted region showed an extremely low current of 6.5 × 10-12 A under a gate voltage value up to 10 V, thus demonstrating that the parasitic MOSFET in the isolation region was eliminated by boron field implantation. The off-state drain current of the rectangular MOSFET with boron field implantation was 5.5 × 10-11 A, which was only one order of magnitude higher than the 6.6 × 10-12 A of the circular device. By contrast, the rectangular MOSFET with mesa isolation presented an off-state drain current of 3.2 × 10-9 A. The field isolation for GaN MOSFETs was achieved by using boron field implantation. The implantation did not reduce the field-effect mobility. The isolation structure of both mesa and implantation did not influence the subthreshold swing, whereas the isolation structure of only the implantation increased the subthreshold swing. The breakdown voltage of the implanted region with 5 μm spacing was up to 901.5 V.

  3. 48 CFR 1852.236-74 - Magnitude of requirement.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 6 2011-10-01 2011-10-01 false Magnitude of requirement... 1852.236-74 Magnitude of requirement. As prescribed in 1836.570(d), insert the following provision: Magnitude of Requirement (DEC 1988) The Government estimated price range of this project is...

  4. 48 CFR 1852.236-74 - Magnitude of requirement.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 6 2013-10-01 2013-10-01 false Magnitude of requirement... 1852.236-74 Magnitude of requirement. As prescribed in 1836.570(d), insert the following provision: Magnitude of Requirement (DEC 1988) The Government estimated price range of this project is...

  5. Numerical Magnitude Processing in Children with Mild Intellectual Disabilities

    ERIC Educational Resources Information Center

    Brankaer, Carmen; Ghesquiere, Pol; De Smedt, Bert

    2011-01-01

    The present study investigated numerical magnitude processing in children with mild intellectual disabilities (MID) and examined whether these children have difficulties in the ability to represent numerical magnitudes and/or difficulties in the ability to access numerical magnitudes from formal symbols. We compared the performance of 26 children…

  6. 48 CFR 1852.236-74 - Magnitude of requirement.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 6 2014-10-01 2014-10-01 false Magnitude of requirement... 1852.236-74 Magnitude of requirement. As prescribed in 1836.570(d), insert the following provision: Magnitude of Requirement (DEC 1988) The Government estimated price range of this project is...

  7. 48 CFR 1852.236-74 - Magnitude of requirement.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Magnitude of requirement... 1852.236-74 Magnitude of requirement. As prescribed in 1836.570(d), insert the following provision: Magnitude of Requirement (DEC 1988) The Government estimated price range of this project is...

  8. 48 CFR 1852.236-74 - Magnitude of requirement.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 6 2012-10-01 2012-10-01 false Magnitude of requirement... 1852.236-74 Magnitude of requirement. As prescribed in 1836.570(d), insert the following provision: Magnitude of Requirement (DEC 1988) The Government estimated price range of this project is...

  9. Symbolic Magnitude Modulates Perceptual Strength in Binocular Rivalry

    ERIC Educational Resources Information Center

    Paffen, Chris L. E.; Plukaard, Sarah; Kanai, Ryota

    2011-01-01

    Basic aspects of magnitude (such as luminance contrast) are directly represented by sensory representations in early visual areas. However, it is unclear how symbolic magnitudes (such as Arabic numerals) are represented in the brain. Here we show that symbolic magnitude affects binocular rivalry: perceptual dominance of numbers and objects of…

  10. Sign-And-Magnitude Up/Down Counter

    NASA Technical Reports Server (NTRS)

    Cole, Steven W.

    1991-01-01

    Magnitude-and-sign counter includes conventional up/down counter for magnitude part and special additional circuitry for sign part. Negative numbers indicated more directly. Counter implemented by programming erasable programmable logic device (EPLD) or programmable logic array (PLA). Used in place of conventional up/down counter to provide sign and magnitude values directly to other circuits.

  11. Implant-induced microdamage in osteoporotic bone.

    PubMed

    Yu, Zhi-Feng; Tang, Ting-Ting; Qiu, Shi-Jing

    2012-01-01

    With the increase of elderly population, more and more implant operations need to be performed in osteoporotic bone, while different forms of microdamage will be produced in peri-implant bone intraoperatively, including high- and low-density diffuse damages, as well as linear cracks. The length and location of the microcracks are the main factors in affecting the biomechanical performance of bone. Suppression of bone remodeling by bisphosphonates may lead to microdamage accumulation, which is often accompanied with the decrease of bone strength and the increase of bone fragility. Microdamage can be repaired by bone remodeling or mineralization to maintain the strength and structural integrity. Both remo- deling and mineralization can affect the bone quality and long-term implant stability. In this paper, we make a brief summary of some important issues and research progresses in this field. PMID:22480676

  12. Binocular disparity magnitude affects perceived depth magnitude despite inversion of depth order.

    PubMed

    Matthews, Harold; Hill, Harold; Palmisano, Stephen

    2011-01-01

    The hollow-face illusion involves a misperception of depth order: our perception follows our top-down knowledge that faces are convex, even though bottom-up depth information reflects the actual concave surface structure. While pictorial cues can be ambiguous, stereopsis should unambiguously indicate the actual depth order. We used computer-generated stereo images to investigate how, if at all, the sign and magnitude of binocular disparities affect the perceived depth of the illusory convex face. In experiment 1 participants adjusted the disparity of a convex comparison face until it matched a reference face. The reference face was either convex or hollow and had binocular disparities consistent with an average face or had disparities exaggerated, consistent with a face stretched in depth. We observed that apparent depth increased with disparity magnitude, even when the hollow faces were seen as convex (ie when perceived depth order was inconsistent with disparity sign). As expected, concave faces appeared flatter than convex faces, suggesting that disparity sign also affects perceived depth. In experiment 2, participants were presented with pairs of real and illusory convex faces. In each case, their task was to judge which of the two stimuli appeared to have the greater depth. Hollow faces with exaggerated disparities were again perceived as deeper. PMID:22132512

  13. Development of an Empirical Local Magnitude Formula for Northern Oklahoma

    NASA Astrophysics Data System (ADS)

    Spriggs, N.; Karimi, S.; Moores, A. O.

    2015-12-01

    In this paper we focus on determining a local magnitude formula for northern Oklahoma that is unbiased with distance by empirically constraining the attenuation properties within the region of interest based on the amplitude of observed seismograms. For regional networks detecting events over several hundred kilometres, distance correction terms play an important role in determining the magnitude of an event. Standard distance correction terms such as Hutton and Boore (1987) may have a significant bias with distance if applied in a region with different attenuation properties, resulting in an incorrect magnitude. We have presented data from a regional network of broadband seismometers installed in bedrock in northern Oklahoma. The events with magnitude in the range of 2.0 and 4.5, distributed evenly across this network are considered. We find that existing models show a bias with respect to hypocentral distance. Observed amplitude measurements demonstrate that there is a significant Moho bounce effect that mandates the use of a trilinear attenuation model in order to avoid bias in the distance correction terms. We present two different approaches of local magnitude calibration. The first maintains the classic definition of local magnitude as proposed by Richter. The second method calibrates local magnitude so that it agrees with moment magnitude where a regional moment tensor can be computed. To this end, regional moment tensor solutions and moment magnitudes are computed for events with magnitude larger than 3.5 to allow calibration of local magnitude to moment magnitude. For both methods the new formula results in magnitudes systematically lower than previous values computed with Eaton's (1992) model. We compare the resulting magnitudes and discuss the benefits and drawbacks of each method. Our results highlight the importance of correct calibration of the distance correction terms for accurate local magnitude assessment in regional networks.

  14. Implant interactions with orthodontics.

    PubMed

    Celenza, Frank

    2012-09-01

    Many situations arise in which orthodontic therapy in conjunction with implant modalities is beneficial, relevant or necessary. These situations might entail orthodontic treatment preparatory to the placement of an implant, such as in the site preparation for implant placement. Traditionally, this has been somewhat well understood, but there are certain guidelines that must be adhered to as well as diagnostic steps that must be followed. Provision of adequate space for implant placement is of paramount importance, but there is also the consideration of tissue manipulation and remodeling which orthodontic therapy can achieve very predictably and orthodontists should be well versed in harnessing and employing this modality of site preparation. In this way, hopeless teeth that are slated for extraction can still be utilized by orthodontic extraction to augment tissues, both hard and soft, thereby facilitating site development. On the corollary, and representing a significant shift in treatment sequencing, there are many situations in which orthodontic mechanotherapy can be simplified, expedited, and facilitated by the placement of an implant and utilization as an integral part of the mechanotherapy. Implants have proven to provide excellent anchorage, and have resulted in a new class of anchorage known as "absolute anchorage". Implants can be harnessed as anchors both in a direct and indirect sense, depending upon the dictates of the case. Further, this has led to the development of orthodontic miniscrew systems and techniques, which can have added features such as flexibility in location and placement, as well as ease of use and removal. As orthodontic appliances evolve, the advent of aligner therapy has become mainstream and well accepted, and many of the aforementioned combined treatment modalities can and should be incorporated into this relatively new treatment modality as well. PMID:23040348

  15. The Biolink Implantable Telemetry System

    NASA Technical Reports Server (NTRS)

    Betancourt-Zamora, Rafael J.

    1999-01-01

    Most biotelemetry applications deal with the moderated data rates of biological signals. Few people have studied the problem of transcutaneous data transmission at the rates required by NASA's Life Sciences-Advanced BioTelemetry System (LS-ABTS). Implanted telemetry eliminate the problems associated with wire breaking the skin, and permits experiments with awake and unrestrained subjects. Our goal is to build a low-power 174-216MHz Radio Frequency (RF) transmitter suitable for short range biosensor and implantable use. The BioLink Implantable Telemetry System (BITS) is composed of three major units: an Analog Data Module (ADM), a Telemetry Transmitter Module (TTM), and a Command Receiver Module (CRM). BioLink incorporates novel low-power techniques to implement a monolithic digital RF transmitter operating at 100kbps, using quadrature phase shift keying (QPSK) modulation in the 174-216MHz ISM band. As the ADM will be specific for each application, we focused on solving the problems associated with a monolithic implementation of the TTM and CRM, and this is the emphasis of this report. A system architecture based on a Frequency-Locked Loop (FLL) Frequency Synthesizer is presented, and a novel differential frequency that eliminates the need for a frequency divider is also shown. A self sizing phase modulation scheme suitable for low power implementation was also developed. A full system-level simulation of the FLL was performed and loop filter parameters were determined. The implantable antenna has been designed, simulated and constructed. An implant package compatible with the ABTS requirements is also being proposed. Extensive work performed at 200MHz in 0.5um complementary metal oxide semiconductors (CMOS) showed the feasibility of integrating the RF transmitter circuits in a single chip. The Hajimiri phase noise model was used to optimize the Voltage Controlled Oscillator (VCO) for minimum power consumption. Two test chips were fabricated in a 0.5pm, 3V CMOS

  16. Effects of ion implantation on the photoferroelectric properties of lead lanthanum zirconate titanate ceramics

    SciTech Connect

    Land, C.E.; Peercy, P.S.

    1981-01-01

    Earlier studies of Ar-, Ar + Ne- and Ar + Ne + He- implanted ferroelectric-phase lead lanthanum zirconate titanate (PLZT) ceramics indicate that ion implantation can increase the intrinsic (near-uv) photoferroelectric sensitivity by more than four orders of magnitude compared to that of unimplanted PLZT. More recent studies involving implantation of chemically active ions, e.g., Al and Cr, indicate that the absorption spectrum of the implanted region can be extended from the near-uv to the visible, and that the extrinsic (visible-light) photoferroelectric sensitivity can be improved substantially with respect to that of PLZT implanted with inert ions. The results of these studies are reviewed and photographic sensitivities of Ar-, Ar + Ne-, Ar + Ne + He-, Al-, Cr-, Fe-, and Fe + Ne- implanted PLZT at both near-uv and visible-light wavelengths are compared with the sensitivities of other image storage media.

  17. Influence of Temperature on Nitrogen Ion Implantation of Ti6Al4V Alloy

    NASA Astrophysics Data System (ADS)

    Zhao, Qing; Zheng, Yong-zhen; Mo, Zhi-tao; Tang, De-li; Tong, Hong-hui; Geng, Man

    2001-04-01

    In order to achieve increased layer thickness, and wearing resistance, enhanced ion implantation with nitrogen has been carried out at temperatures of 100, 200, 400, and 600°C with a dose of 4×1018 ions cm-2. Using the Plasma Source Ion Implantation (PSII) device, specimens of Ti6Al4V alloy were implanted at elevated temperatures, using the ion flux as the heating source. Auger Electron Spectroscopy (AES), Scanning Electron Microscopy (SEM), x-ray Diffraction (XRD), micro-hardness measurements and pin-on-disk wearing tester were utilized to evaluate the surface property improvements. The thickness of the implanted layer increased by about an order of magnitude when the temperature was elevated from 100 to 600°C. Higher surface hardness and wearing resistance was also obtained in implantation under higher temperature. XRD image showed the presence of titanium nitrides on the implanted surface.

  18. Comparison of Implant Stability Using Resonance Frequency Analysis: Osteotome Versus Conventional Drilling

    PubMed Central

    Sadeghi, Rokhsareh; Miremadi, Asghar

    2015-01-01

    Objectives: Implant primary stability is one of the important factors in achieving implant success. The osteotome technique may improve primary stability in patients with poor bone quality. The aim of this study was to compare implant stability using two different techniques namely osteotome versus conventional drilling in the posterior maxilla. Materials and Methods: In this controlled randomized clinical trial, 54 dental implants were placed in 32 patients; 29 implants were placed in the osteotome group and 25 in the conventional drilling group. Implant stability was assessed at four time intervals namely at baseline, one, two and three months after implant placement using resonance frequency analysis (RFA). Results: Primary stability based on implant stability quotient (ISQ) units was 71.4±7 for the osteotome group and 67.4±10 for the control group. There was no statistically significant difference between the two groups in implant stability at any of the measurement times. In each group, changes in implant stability from baseline to one month and also from two months to three months post-operatively were not significant but from one month to two months after implant placement, implant stability showed a significant increase in both groups. Conclusion: The results of this study revealed that in both techniques, good implant stability was achieved and osteotome technique did not have any advantage compared to conventional drilling in this regard. PMID:27148375

  19. Stress magnitudes in the crust: constraints from stress orientation and relative magnitude data

    USGS Publications Warehouse

    Zoback, M.L.; Magee, M.

    1991-01-01

    The World Stress Map Project is a global cooperative effort to compile and interpret data on the orientation and relative magnitudes of the contemporary in situ tectonic stress field in the Earth's lithosphere. The intraplate stress field in both the oceans and continents is largely compressional with one or both of the horizontal stresses greater than the vertical stress. The regionally uniform horizontal intraplate stress orientations are generally consistent with either relative or absolute plate motions indicating that plate-boundary forces dominate the stress distribution within the plates. Current models of stresses due to whole mantle flow inferred from seismic topography models predict a general compressional stress state within continents but do not match the broad-scale horizontal stress orientations. The broad regionally uniform intraplate stress orientations are best correlated with compressional plate-boundary forces and the geometry of the plate boundaries. -from Authors

  20. A feasibility study for removing tissue contamination from porous implants.

    PubMed

    Carr, J M; Levine, D B; Bennett, A P; Torzilli, P A; Crow, M K; Grigiene, R

    1995-01-01

    Porous implants that are unpackaged in the operating room but not implanted are discarded because they must be considered potentially contaminated with tissue. To reduce this waste, a method was developed to decontaminate these implants so that they can be resterilized and implanted. This method consists of ultrasonic scrubbing, sequentially, in aqueous solutions of dishwashing detergent, 7% nitric acid, and 5.25% sodium hypochlorite. The effectiveness of the method was tested by contaminating samples of porous implants with tissue, subjecting them to the decontamination method, and then using the following techniques to determine whether any tissue remained. The weights of samples after decontamination were compared with their weights before contamination. The rate of removal of labeled protein contamination from samples was measured. The capacity of decontaminated samples to activate immune system cells was assayed. Bioburden evaluations were performed on decontaminated samples. Within the measurement capabilities of each technique, no tissue was detected in any sample after decontamination. PMID:7613569

  1. 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

  2. Positron implantation in solids

    SciTech Connect

    Ghosh, V.J.; Lynn, K.G.; Welch, D.O.

    1993-12-31

    The Monte Carlo technique for modeling positron prior to annihilation and electron implantation in semi-infinite metals is described. Particle implantation is modelled as a multistep process, a series of collisions with the atoms of the host material. In elastic collisions with neutral atoms there is no transfer of energy. The particle loses energy by several different channels, excitation of the electron gas, ionization of the ion cores, or, at low energies, by phonon excitation. These competing scattering mechanisms have been incorporated into the Monte Carlo framework and several different models are being used. Brief descriptions of these Monte Carlo schemes, as well as an analytic model for positron implantation are included. Results of the Monte Carlo simulations are presented and compared with expermental data. Problems associated with modeling positron implantation are discuss and the need for more expermental data on energy-loss in different materials is stressed. Positron implantation in multilayers of different metals is briefly described and extensions of this work to include a study of multilayers and heterostructures is suggested.

  3. Cochlear implant and delayed facial palsy.

    PubMed

    Joseph, Shawn Thadathil; Vishwakarma, Rajesh; Ramani, Mukesh Kumar; Aurora, Rupa

    2009-12-01

    Delayed facial nerve palsy following cochlear implant surgery is less documented though it poses diagnostic and therapeutic challenges. Apart from the functional, aesthetic and emotional concerns, it can raise important medico legal issues. The objectives of this study were: to report a case of delayed facial palsy following cochlear implant surgery in a patient who had positive viral antibody markers pre operatively; and to review the literature on delayed onset facial paralysis following viral reactivation and its relation to cochlear implant surgery. An extensive literature review was done using internet and medical search engines and library facilities. Important articles on the topic were identified and summarised. Data on delayed facial palsy following cochlear implant surgery were collected, constructed in a coherent way and details discussed. Postulated mechanisms of delayed facial palsy include neural oedema, vasospasm and viral reactivation. Of these, reactivation of previous herpes simplex virus infection has special significance, as many of these patients are positive for viral antibody markers. Manipulation of sensory branches of the facial nerve and chorda tympani can be a mechanism in such cases. Correlation of clinical presentation and pre operative positive viral antibody markers with positive polymerase chain reaction can be strongly suggestive of viral reactivation. It is concluded that patients with positive viral antibody markers are more susceptible to facial palsy from viral reactivation. Corticosteroids, antiviral agents and physiotherapy can be useful in producing a quicker and complete recovery. An experienced cochlear implant surgery team and pre operative radiological evaluations are mandatory to decrease the chances of direct facial nerve trauma. Proper irrigation lowers the risk of neural oedema. PMID:19194876

  4. The Vestibular Implant: Quo Vadis?

    PubMed Central

    van de Berg, Raymond; Guinand, Nils; Stokroos, Robert J.; Guyot, Jean-Philippe; Kingma, Herman

    2011-01-01

    Objective: To assess the progress of the development of the vestibular implant (VI) and its feasibility short-term. Data sources: A search was performed in Pubmed, Medline, and Embase. Key words used were “vestibular prosth*” and “VI.” The only search limit was language: English or Dutch. Additional sources were medical books, conference lectures and our personal experience with per-operative vestibular stimulation in patients selected for cochlear implantation. Study selection: All studies about the VI and related topics were included and evaluated by two reviewers. No study was excluded since every study investigated different aspects of the VI. Data extraction and synthesis: Data was extracted by the first author from selected reports, supplemented by additional information, medical books conference lectures. Since each study had its own point of interest with its own outcomes, it was not possible to compare data of different studies. Conclusion: To use a basic VI in humans seems feasible in the very near future. Investigations show that electric stimulation of the canal nerves induces a nystagmus which corresponds to the plane of the canal which is innervated by the stimulated nerve branch. The brain is able to adapt to a higher baseline stimulation, while still reacting on a dynamic component. The best response will be achieved by a combination of the optimal stimulus (stimulus profile, stimulus location, precompensation), complemented by central vestibular adaptation. The degree of response will probably vary between individuals, depending on pathology and their ability to adapt. PMID:21991260

  5. 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

  6. Modulation Techniques for Biomedical Implanted Devices and Their Challenges

    PubMed Central

    Hannan, Mahammad A.; Abbas, Saad M.; Samad, Salina A.; Hussain, Aini

    2012-01-01

    Implanted medical devices are very important electronic devices because of their usefulness in monitoring and diagnosis, safety and comfort for patients. Since 1950s, remarkable efforts have been undertaken for the development of bio-medical implanted and wireless telemetry bio-devices. Issues such as design of suitable modulation methods, use of power and monitoring devices, transfer energy from external to internal parts with high efficiency and high data rates and low power consumption all play an important role in the development of implantable devices. This paper provides a comprehensive survey on various modulation and demodulation techniques such as amplitude shift keying (ASK), frequency shift keying (FSK) and phase shift keying (PSK) of the existing wireless implanted devices. The details of specifications, including carrier frequency, CMOS size, data rate, power consumption and supply, chip area and application of the various modulation schemes of the implanted devices are investigated and summarized in the tables along with the corresponding key references. Current challenges and problems of the typical modulation applications of these technologies are illustrated with a brief suggestions and discussion for the progress of implanted device research in the future. It is observed that the prime requisites for the good quality of the implanted devices and their reliability are the energy transformation, data rate, CMOS size, power consumption and operation frequency. This review will hopefully lead to increasing efforts towards the development of low powered, high efficient, high data rate and reliable implanted devices. PMID:22368470

  7. Implantable Heart Aid

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Medrad utilized NASA's Apollo technology to develop a new device called the AID implantable automatic pulse generator which monitors the heart continuously, recognizes the onset of ventricular fibrillation and delivers a corrective electrical shock. AID pulse generator is, in effect, a miniaturized version of the defibrillator used by emergency squads and hospitals to restore rhythmic heartbeat after fibrillation, but has the unique advantage of being permanently available to the patient at risk. Once implanted, it needs no specially trained personnel or additional equipment. AID system consists of a microcomputer, a power source and two electrodes which sense heart activity.

  8. Hydroxylapatite Otologic Implants

    SciTech Connect

    McMillan, A.D.; Lauf, R.J.; Beale, B.; Johnson, R.

    2000-01-01

    A Cooperative Research and Development Agreement (CRADA) between Lockheed Martin Energy Research Corporation (LMER) and Smith and Nephew Richards Inc. of Bartlett, TN, was initiated in March 1997. The original completion date for the Agreement was March 25, 1998. The purpose of this work is to develop and commercialize net shape forming methods for directly creating dense hydroxylapatite (HA) ceramic otologic implants. The project includes three tasks: (1) modification of existing gelcasting formulations to accommodate HA slurries; (2) demonstration of gelcasting to fabricate green HA ceramic components of a size and shape appropriate to otologic implants: and (3) sintering and evaluation of the HA components.

  9. Ion implantation in silicate glasses

    SciTech Connect

    Arnold, G.W.

    1993-12-01

    This review examines the effects of ion implantation on the physical properties of silicate glasses, the compositional modifications that can be brought about, and the use of metal implants to form colloidal nanosize particles for increasing the nonlinear refractive index.

  10. Current trends in dental implants

    PubMed Central

    Gaviria, Laura; Salcido, John Paul; Guda, Teja

    2014-01-01

    Tooth loss is very a very common problem; therefore, the use of dental implants is also a common practice. Although research on dental implant designs, materials and techniques has increased in the past few years and is expected to expand in the future, there is still a lot of work involved in the use of better biomaterials, implant design, surface modification and functionalization of surfaces to improve the long-term outcomes of the treatment. This paper provides a brief history and evolution of dental implants. It also describes the types of implants that have been developed, and the parameters that are presently used in the design of dental implants. Finally, it describes the trends that are employed to improve dental implant surfaces, and current technologies used for the analysis and design of the implants. PMID:24868501

  11. Influence of bone quality on stress distribution for endosseous implants.

    PubMed

    Holmes, D C; Loftus, J T

    1997-01-01

    The present study examined the influence of bone quality on the transmission of occlusal forces for endosseous dental implants. Employing the finite element method, the study modeled a 3.75 x 10-mm threaded implant placed in a 12 x 11 x 8-mm section of bone. By varying the elastic parameters assigned to the bone elements, four bone quality categories were established. A load of 100 N was applied at the occlusal surface of the restoration at a 30 degrees angle to the vertical axis of the implant. Maximum von Mises stress concentrations (sigma Emax) were observed to be located in the marginal bone at the coronal aspect of the implant fixture in all four cases. Values of sigma Emax were 13.7 MPa for type 1 bone, 15.8 MPa for type 2 bone, 20.1 MPa for type 3 bone, and 26.5 MPa for type 4 bone. Magnitude of the stresses in bone was strongly correlated (r = 0.997) with computed displacement of the implant system. This analysis predicts that placement of implants in bone with greater thickness of the cortical shell and greater density of the core will result in less micromovement and reduced stress concentration, thereby increasing the likelihood of fixture stabilization and tissue integration. PMID:9477847

  12. EFFECT OF MECHANICAL STIMULI ON SKELETAL REGENERATION AROUND IMPLANTS

    PubMed Central

    Leucht, Philipp; Kim, Jae-Beom; Wazen, Rima; Currey, Jennifer A.; Nanci, Antonio; Brunski, John B.; Helms, Jill A.

    2007-01-01

    Due to the aging population and the increasing need for total joint replacements, osseointegration is of a great interest for various clinical disciplines. Our objective was to investigate the molecular and cellular foundation that underlies this process. Here, we used an in vivo mouse model to study the cellular and molecular response in three distinct areas of unloaded implants: the periosteum, the gap between implant and cortical bone, and the marrow space. Our analyses began with the early phases of healing, and continued until the implants were completely osseointegrated. We investigated aspects of osseointegration ranging from vascularization, cell proliferation, differentiation, and bone remodeling. In doing so, we gained an understanding of the healing mechanisms of different skeletal tissues during unloaded implant osseointegration. To continue our analysis, we used a micromotion device to apply a defined physical stimulus to the implants, and in doing so, we dramatically enhanced bone formation in the peri-implant tissue. By comparing strain measurements with cellular and molecular analyses, we developed an understanding of the correlation between strain magnitudes and fate decisions of cells shaping the skeletal regenerate. PMID:17175211

  13. Kharkiv Asteroid Magnitude-Phase Relations V1.0

    NASA Astrophysics Data System (ADS)

    Shevchenko, V. G.; Belskaya, I. N.; Lupishko, D. F.; Krugly, Yu. N.; Chiorny, V. G.; Velichko, F. P.

    2010-08-01

    A database of asteroid magnitude-phase relations compiled at the Institute of Astronomy of Kharkiv Kharazin University by Shevchenko et al., including observations from 1978 through 2008. Mainly the observations were performed at the Institute of Astronomy (Kharkiv, Ukraine) and at the Astrophysics Institute (Dushanbe, Tadjikistan). For most asteroids the magnitude-phase relations were obtained down to phase angles less than 1 deg. For some asteroids the magnitudes are presented in three (UBV) or four (BVRI) standard spectral bands.

  14. Metal levels in corrosion of spinal implants

    PubMed Central

    Beguiristain, Jose; Duart, Julio

    2007-01-01

    Corrosion affects spinal instrumentations and may cause local and systemic complications. Diagnosis of corrosion is difficult, and nowadays it is performed almost exclusively by the examination of retrieved instrumentations. We conducted this study to determine whether it is possible to detect corrosion by measuring metal levels on patients with posterior instrumented spinal fusion. Eleven asymptomatic patients, with radiological signs of corrosion of their stainless steel spinal instrumentations, were studied by performing determinations of nickel and chromium in serum and urine. Those levels were compared with the levels of 22 patients with the same kind of instrumentation but without evidence of corrosion and to a control group of 22 volunteers without any metallic implants. Statistical analysis of our results revealed that the patients with spinal implants without radiological signs of corrosion have increased levels of chromium in serum and urine (P < 0.001) compared to volunteers without implants. Corrosion significantly raised metal levels, including nickel and chromium in serum and urine when compared to patients with no radiological signs of corrosion and to volunteers without metallic implants (P < 0.001). Metal levels measured in serum have high sensibility and specificity (area under the ROC curve of 0.981). By combining the levels of nickel and chromium in serum we were able to identify all the cases of corrosion in our series of patients. The results of our study confirm that metal levels in serum and urine are useful in the diagnosis of corrosion of spinal implants and may be helpful in defining the role of corrosion in recently described clinical entities such as late operative site pain or late infection of spinal implants. PMID:17256156

  15. MEMS-Based Power Generation Techniques for Implantable Biosensing Applications

    PubMed Central

    Lueke, Jonathan; Moussa, Walied A.

    2011-01-01

    Implantable biosensing is attractive for both medical monitoring and diagnostic applications. It is possible to monitor phenomena such as physical loads on joints or implants, vital signs, or osseointegration in vivo and in real time. Microelectromechanical (MEMS)-based generation techniques can allow for the autonomous operation of implantable biosensors by generating electrical power to replace or supplement existing battery-based power systems. By supplementing existing battery-based power systems for implantable biosensors, the operational lifetime of the sensor is increased. In addition, the potential for a greater amount of available power allows additional components to be added to the biosensing module, such as computational and wireless and components, improving functionality and performance of the biosensor. Photovoltaic, thermovoltaic, micro fuel cell, electrostatic, electromagnetic, and piezoelectric based generation schemes are evaluated in this paper for applicability for implantable biosensing. MEMS-based generation techniques that harvest ambient energy, such as vibration, are much better suited for implantable biosensing applications than fuel-based approaches, producing up to milliwatts of electrical power. High power density MEMS-based approaches, such as piezoelectric and electromagnetic schemes, allow for supplemental and replacement power schemes for biosensing applications to improve device capabilities and performance. In addition, this may allow for the biosensor to be further miniaturized, reducing the need for relatively large batteries with respect to device size. This would cause the implanted biosensor to be less invasive, increasing the quality of care received by the patient. PMID:22319362

  16. The ruptured PIP breast implant.

    PubMed

    Helyar, V; Burke, C; McWilliams, S

    2013-08-01

    Public concern erupted about the safety of Poly Implant Prothèse (PIP) breast implants when it was revealed in 2011 that they contained an inferior, unlicensed industrial-grade silicone associated with a high rate of rupture. There followed national guidance for UK clinicians, which led to a considerable increase in referrals of asymptomatic women for breast implant assessment. In this review we discuss possible approaches to screening the PIP cohort and the salient characteristics of a ruptured implant. PMID:23622796

  17. Rehabilitation using single stage implants

    PubMed Central

    Mohamed, Jumshad B.; Sudarsan, Sabitha; Arun, K. V.; Shivakumar, B.

    2009-01-01

    Implant related prosthesis has become an integral part of rehabilitation of edentulous areas. Single stage implant placement has become popular because of its ease of use and fairly predictable results. In this paper, we present a series of cases of single stage implants being used to rehabilitate different clinical situations. All the implants placed have been successfully restored and followed up for up to one year. PMID:20376239

  18. Swanson's silastic implants in great toes.

    PubMed

    Sethu, A; D'Netto, D C; Ramakrishna, B

    1980-02-01

    This is a review of 77 partial replacement and interposition arthroplasties in which Silastic implants were used. The operations were carried out between 1971 and 1977 on the metatarsophalangeal joints of the great toes of 62 patients. Twenty-six of the operations were for painful hallux rigidus and 51 for hallux valgus. The patients were reviewed 12 to 92 months after operation, the average follow-up being 60 months. The analysis of results indicated that while the procedure may be suitable for hallux rigidus its use for hallux valgus is not fully satisfactory in the long run. PMID:7351441

  19. Prosthetic failure in implant dentistry.

    PubMed

    Sadid-Zadeh, Ramtin; Kutkut, Ahmad; Kim, Hyeongil

    2015-01-01

    Although osseointegrated dental implants have become a predictable and effective modality for the treatment of single or multiple missing teeth, their use is associated with clinical complications. Such complications can be biologic, technical, mechanical, or esthetic and may compromise implant outcomes to various degrees. This article presents prosthetic complications accompanied with implant-supported single and partial fixed dental prostheses. PMID:25434566

  20. An empirical evolutionary magnitude estimation for earthquake early warning

    NASA Astrophysics Data System (ADS)

    Wu, Yih-Min; Chen, Da-Yi

    2016-04-01

    For earthquake early warning (EEW) system, it is a difficult mission to accurately estimate earthquake magnitude in the early nucleation stage of an earthquake occurrence because only few stations are triggered and the recorded seismic waveforms are short. One of the feasible methods to measure the size of earthquakes is to extract amplitude parameters within the initial portion of waveform after P-wave arrival. However, a large-magnitude earthquake (Mw > 7.0) may take longer time to complete the whole ruptures of the causative fault. Instead of adopting amplitude contents in fixed-length time window, that may underestimate magnitude for large-magnitude events, we suppose a fast, robust and unsaturated approach to estimate earthquake magnitudes. In this new method, the EEW system can initially give a bottom-bund magnitude in a few second time window and then update magnitude without saturation by extending the time window. Here we compared two kinds of time windows for adopting amplitudes. One is pure P-wave time widow (PTW); the other is whole-wave time window after P-wave arrival (WTW). The peak displacement amplitude in vertical component were adopted from 1- to 10-s length PTW and WTW, respectively. Linear regression analysis were implemented to find the empirical relationships between peak displacement, hypocentral distances, and magnitudes using the earthquake records from 1993 to 2012 with magnitude greater than 5.5 and focal depth less than 30 km. The result shows that using WTW to estimate magnitudes accompanies with smaller standard deviation. In addition, large uncertainties exist in the 1-second time widow. Therefore, for magnitude estimations we suggest the EEW system need to progressively adopt peak displacement amplitudes form 2- to 10-s WTW.

  1. Comparison of local magnitude scales in Central Europe

    NASA Astrophysics Data System (ADS)

    Kysel, Robert; Kristek, Jozef; Moczo, Peter; Cipciar, Andrej; Csicsay, Kristian; Srbecky, Miroslav; Kristekova, Miriam

    2015-04-01

    Efficient monitoring of earthquakes and determination of their magnitudes are necessary for developing earthquake catalogues at a regional and national levels. Unification and homogenization of the catalogues in terms of magnitudes has great importance for seismic hazard assessment. Calibrated local earthquake magnitude scales are commonly used for determining magnitudes of regional earthquakes by all national seismological services in the Central Europe. However, at the local scale, each seismological service uses its own magnitude determination procedure. There is no systematic comparison of the approaches and there is no unified procedure. We present a comparison of the local magnitude scales used by the national seismological services of Slovakia (Geophysical Institute, Slovak Academy of Sciences), Czech Republic (Institute of Geophysics, Academy of Sciences of the Czech Republic), Austria (ZAMG), Hungary (Geodetic and Geophysical Institute, Hungarian Academy of Sciences) and Poland (Institute of Geophysics, Polish Academy of Sciences), and by the local network of seismic stations located around the Nuclear Power Plant Jaslovske Bohunice, Slovakia. The comparison is based on the national earthquake catalogues and annually published earthquake bulletins for the period from 1985 to 2011. A data set of earthquakes has been compiled based on identification of common events in the national earthquake catalogues and bulletins. For each pair of seismic networks, magnitude differences have been determined and investigated as a function of time. The mean and standard deviations of the magnitude differences as well as regression coefficients between local magnitudes from the national seismological networks have been computed. Results show relatively big scatter between different national local magnitudes and its considerable time variation. A conversion between different national local magnitudes in a scale 1:1 seems inappropriate, especially for the compilation of the

  2. Implantable Drug Dispenser

    NASA Technical Reports Server (NTRS)

    Collins, E. R. J.

    1983-01-01

    Drugs such as insulin are injected as needed directly into bloodstream by compact implantable dispensing unit. Two vapor cavities produce opposing forces on drug-chamber diaphragm. Heaters in cavities allow control of direction and rate of motion of bellows. Dispensing capsule fitted with coil so batteries can be recharged by induction.

  3. Allergy to Surgical Implants.

    PubMed

    Pacheco, Karin A

    2015-01-01

    Surgical implants have a wide array of therapeutic uses, most commonly in joint replacements, but also in repair of pes excavatum and spinal disorders, in cardiac devices (stents, patches, pacers, valves), in gynecological implants, and in dentistry. Many of the metals used are immunologically active, as are the methacrylates and epoxies used in conjunction with several of these devices. Allergic responses to surgical components can present atypically as failure of the device, with nonspecific symptoms of localized pain, swelling, warmth, loosening, instability, itching, or burning; localized rash is infrequent. Identification of the specific metal and cement components used in a particular implant can be difficult, but is crucial to guide testing and interpretation of results. Nickel, cobalt, and chromium remain the most common metals implicated in implant failure due to metal sensitization; methacrylate-based cements are also important contributors. This review will provide a guide on how to assess and interpret the clinical history, identify the components used in surgery, test for sensitization, and provide advice on possible solutions. Data on the pathways of metal-induced immune stimulation are included. In this setting, the allergist, the dermatologist, or both have the potential to significantly improve surgical outcomes and patient care. PMID:26362550

  4. Semiconductor Ion Implanters

    SciTech Connect

    MacKinnon, Barry A.; Ruffell, John P.

    2011-06-01

    In 1953 the Raytheon CK722 transistor was priced at $7.60. Based upon this, an Intel Xeon Quad Core processor containing 820,000,000 transistors should list at $6.2 billion. Particle accelerator technology plays an important part in the remarkable story of why that Intel product can be purchased today for a few hundred dollars. Most people of the mid twentieth century would be astonished at the ubiquity of semiconductors in the products we now buy and use every day. Though relatively expensive in the nineteen fifties they now exist in a wide range of items from high-end multicore microprocessors like the Intel product to disposable items containing 'only' hundreds or thousands like RFID chips and talking greeting cards. This historical development has been fueled by continuous advancement of the several individual technologies involved in the production of semiconductor devices including Ion Implantation and the charged particle beamlines at the heart of implant machines. In the course of its 40 year development, the worldwide implanter industry has reached annual sales levels around $2B, installed thousands of dedicated machines and directly employs thousands of workers. It represents in all these measures, as much and possibly more than any other industrial application of particle accelerator technology. This presentation discusses the history of implanter development. It touches on some of the people involved and on some of the developmental changes and challenges imposed as the requirements of the semiconductor industry evolved.

  5. Semiconductor Ion Implanters

    NASA Astrophysics Data System (ADS)

    MacKinnon, Barry A.; Ruffell, John P.

    2011-06-01

    In 1953 the Raytheon CK722 transistor was priced at 7.60. Based upon this, an Intel Xeon Quad Core processor containing 820,000,000 transistors should list at 6.2 billion! Particle accelerator technology plays an important part in the remarkable story of why that Intel product can be purchased today for a few hundred dollars. Most people of the mid twentieth century would be astonished at the ubiquity of semiconductors in the products we now buy and use every day. Though relatively expensive in the nineteen fifties they now exist in a wide range of items from high-end multicore microprocessors like the Intel product to disposable items containing `only' hundreds or thousands like RFID chips and talking greeting cards. This historical development has been fueled by continuous advancement of the several individual technologies involved in the production of semiconductor devices including Ion Implantation and the charged particle beamlines at the heart of implant machines. In the course of its 40 year development, the worldwide implanter industry has reached annual sales levels around 2B, installed thousands of dedicated machines and directly employs thousands of workers. It represents in all these measures, as much and possibly more than any other industrial application of particle accelerator technology. This presentation discusses the history of implanter development. It touches on some of the people involved and on some of the developmental changes and challenges imposed as the requirements of the semiconductor industry evolved.

  6. The reverse zygomatic implant: a new implant for maxillofacial reconstruction.

    PubMed

    Dawood, Andrew; Collier, Jonathan; Darwood, Alastair; Tanner, Susan

    2015-01-01

    This case report describes the rehabilitation of a patient who had been treated with a hemimaxillectomy, reconstruction with a latissimus dorsi vascularized free flap, and radiotherapy for carcinoma of the sinus some years previously. Limited jaw opening, difficult access through the flap to the bony site, and the very small amount of bone available in which to anchor the implant inspired the development and use of a new "reverse zygomatic" implant. For this treatment, site preparation and implant insertion were accomplished using an extraoral approach. The implant was used along with two other conventional zygomatic implants to provide support for a milled titanium bar and overdenture to rehabilitate the maxilla. Two years later, the patient continues to enjoy a healthy reconstruction. The reverse zygomatic implant appears to show promise as a useful addition to the implant armamentarium for the treatment of the patient undergoing maxillectomy. PMID:26574864

  7. Pioneering transcatheter aortic valve Implant (Inovare®) via transfemoral.

    PubMed

    Pontes, José Carlos Dorsa Vieira; Duarte, João Jackson; Silva, Augusto Daige da; Dias, Amaury Mont'Serrat Ávila Souza; Benfatti, Ricardo Adala; Gardenal, Neimar; Benfatti, Amanda Ferreira Carli; Gomes, Jandir Ferreira

    2012-01-01

    We present a patient with severe aortic valvular bioprosthesis dysfunction implanted for 11 years, presenting with acute pulmonary edema due to severe valvular insufficiency with severe systolic dysfunction (EF <30%) and comorbid conditions that amounted operative risk (STS score > 10). We carried out the transcatheter aortic valve implantation (Inovare® - Braile Biomedica), which was implemented successfully by transfemoral access and good patient outcomes. PMID:23288191

  8. Dealing with a left ventricular pseudoaneurysm during assist device implant.

    PubMed

    Ha, Richard V; Chiu, Peter; Banerjee, Dipanjan; Sheikh, Ahmad Y

    2016-06-01

    Despite increasing use of left ventricular devices for the surgical treatment of heart failure, there is limited experience with implantation of devices in the setting of challenging left apical anatomy. We report the case of a 68-year-old man with a chronic post-infarction calcified apical pseudoaneurysm, who underwent pseudoaneurysmectomy, ventricular myoplasty, and left ventricular assist device implantation. A review of the literature and operative strategies are presented. PMID:25834125

  9. The Construction of a Magnitude Estimation Scale of Adult Learning.

    ERIC Educational Resources Information Center

    Blunt, Adrian

    The psychophysical technique of magnitude estimation was used to develop a ratio scale of subjective estimations of adult learning in various adult education activities. A rank order of 26 learning activities and the magnitude estimations in "units of learning" that are expected to occur in each activity were obtained from 146 adult education…

  10. Magnitude Knowledge: The Common Core of Numerical Development

    ERIC Educational Resources Information Center

    Siegler, Robert S.

    2016-01-01

    The integrated theory of numerical development posits that a central theme of numerical development from infancy to adulthood is progressive broadening of the types and ranges of numbers whose magnitudes are accurately represented. The process includes four overlapping trends: 1) representing increasingly precisely the magnitudes of non-symbolic…

  11. Congruency Effects between Number Magnitude and Response Force

    ERIC Educational Resources Information Center

    Vierck, Esther; Kiesel, Andrea

    2010-01-01

    Numbers are thought to be represented in space along a mental left-right oriented number line. Number magnitude has also been associated with the size of grip aperture, which might suggest a connection between number magnitude and intensity. The present experiment aimed to confirm this possibility more directly by using force as a response…

  12. Some Effects of Magnitude of Reinforcement on Persistence of Responding

    ERIC Educational Resources Information Center

    McComas, Jennifer J.; Hartman, Ellie C.; Jimenez, Angel

    2008-01-01

    The influence of magnitude of reinforcement was examined on both response rate and behavioral persistence. During Phase 1, a multiple schedule of concurrent reinforcement was implemented in which reinforcement for one response option was held constant at VI 30 s across both components, while magnitude of reinforcement for the other response option…

  13. Magnitude Knowledge: The Common Core of Numerical Development

    ERIC Educational Resources Information Center

    Siegler, Robert S.

    2016-01-01

    The integrated theory of numerical development posits that a central theme of numerical development from infancy to adulthood is progressive broadening of the types and ranges of numbers whose magnitudes are accurately represented. The process includes four overlapping trends: (1) representing increasingly precisely the magnitudes of non-symbolic…

  14. The Effects of Reinforcer Magnitude on Timing in Rats

    ERIC Educational Resources Information Center

    Ludvig, Elliot A.; Conover, Kent; Shizgal, Peter

    2007-01-01

    The relation between reinforcer magnitude and timing behavior was studied using a peak procedure. Four rats received multiple consecutive sessions with both low and high levels of brain stimulation reward (BSR). Rats paused longer and had later start times during sessions when their responses were reinforced with low-magnitude BSR. When estimated…

  15. Number Games, Magnitude Representation, and Basic Number Skills in Preschoolers

    ERIC Educational Resources Information Center

    Whyte, Jemma Catherine; Bull, Rebecca

    2008-01-01

    The effect of 3 intervention board games (linear number, linear color, and nonlinear number) on young children's (mean age = 3.8 years) counting abilities, number naming, magnitude comprehension, accuracy in number-to-position estimation tasks, and best-fit numerical magnitude representations was examined. Pre- and posttest performance was…

  16. The Weight of Time: Affordances for an Integrated Magnitude System

    ERIC Educational Resources Information Center

    Lu, Aitao; Mo, Lei; Hodges, Bert H.

    2011-01-01

    In five experiments we explored the effects of weight on time in different action contexts to test the hypothesis that an integrated magnitude system is tuned to affordances. Larger magnitudes generally seem longer; however, Lu and colleagues (2009) found that if numbers were presented as weights in a range heavy enough to affect lifting, the…

  17. Reinforcement Magnitude: An Evaluation of Preference and Reinforcer Efficacy

    ERIC Educational Resources Information Center

    Trosclair-Lasserre, Nicole M.; Lerman, Dorothea C.; Call, Nathan A.; Addison, Laura R.; Kodak, Tiffany

    2008-01-01

    Consideration of reinforcer magnitude may be important for maximizing the efficacy of treatment for problem behavior. Nonetheless, relatively little is known about children's preferences for different magnitudes of social reinforcement or the extent to which preference is related to differences in reinforcer efficacy. The purpose of the current…

  18. Prosthodontic management of implant therapy.

    PubMed

    Thalji, Ghadeer; Bryington, Matthew; De Kok, Ingeborg J; Cooper, Lyndon F

    2014-01-01

    Implant-supported dental restorations can be screw-retained, cement-retained, or a combination of both, whereby a metal superstructure is screwed to the implants and crowns are individually cemented to the metal frame. Each treatment modality has advantages and disadvantages. The use of computer-aided design/computer-assisted manufacture technologies for the manufacture of implant superstructures has proved to be advantageous in the quality of materials, precision of the milled superstructures, and passive fit. Maintenance and recall evaluations are an essential component of implant therapy. The longevity of implant restorations is limited by their biological and prosthetic maintenance requirements. PMID:24286654

  19. The Effects Of Reinforcement Magnitude On Functional Analysis Outcomes

    PubMed Central

    2005-01-01

    The duration or magnitude of reinforcement has varied and often appears to have been selected arbitrarily in functional analysis research. Few studies have evaluated the effects of reinforcement magnitude on problem behavior, even though basic findings indicate that this parameter may affect response rates during functional analyses. In the current study, 6 children with autism or developmental disabilities who engaged in severe problem behavior were exposed to three separate functional analyses, each of which varied in reinforcement magnitude. Results of these functional analyses were compared to determine if a particular reinforcement magnitude was associated with the most conclusive outcomes. In most cases, the same conclusion about the functions of problem behavior was drawn regardless of the reinforcement magnitude. PMID:16033163

  20. Multifractal detrended fluctuation analysis of Pannonian earthquake magnitude series

    NASA Astrophysics Data System (ADS)

    Telesca, Luciano; Toth, Laszlo

    2016-04-01

    The multifractality of the series of magnitudes of the earthquakes occurred in Pannonia region from 2002 to 2012 has been investigated. The shallow (depth less than 40 km) and deep (depth larger than 70 km) seismic catalogues were analysed by using the multifractal detrended fluctuation analysis. The shallow and deep catalogues are characterized by different multifractal properties: (i) the magnitudes of the shallow events are weakly persistent, while those of the deep ones are almost uncorrelated; (ii) the deep catalogue is more multifractal than the shallow one; (iii) the magnitudes of the deep catalogue are characterized by a right-skewed multifractal spectrum, while that of the shallow magnitude is rather symmetric; (iv) a direct relationship between the b-value of the Gutenberg-Richter law and the multifractality of the magnitudes is suggested.

  1. Ion-implanted PLZT ceramics: a new high-sensitivity image storage medium

    SciTech Connect

    Peercy, P.S.; Land, C.E.

    1980-01-01

    Results were presented of our studies of photoferroelectric (PFE) image storage in H- and He-ion implanted PLZT (lead lanthanum zirconate titanate) ceramics which demonstrate that the photosensitivity of PLZT can be significantly increased by ion implantation in the ceramic surface to be exposed to image light. More recently, implantations of Ar and Ar + Ne into the PLZT surface have produced much greater photosensitivity enhancement. For example, the photosensitivity after implantation with 1.5 x 10/sup 14/ 350 keV Ar/cm/sup 2/ + 1 x 10/sup 15/ 500 keV Ne/cm/sup 2/ is increased by about four orders of magnitude over that of unimplanted PLZT. Measurements indicate that the photosensitivity enhancement in ion-implanted PLZT is controlled by implantation-produced disorder which results in marked decreases in dielectric constant and dark conductivity and changes in photoconductivity of the implanted layer. The effects of Ar- and Ar + Ne-implantation are presented along with a phenomenological model which describes the enhancement in photosensitivity obtained by ion implantation. This model takes into account both light- and implantation-induced changes in conductivity and gives quantitative agreement with the measured changes in the coercive voltage V/sub c/ as a function of near-uv light intensity for both unimplanted and implanted PLZT. The model, used in conjunction with calculations of the profiles of implantation-produced disorder, has provided the information needed for co-implanting ions of different masses, e.g., Ar and Ne, to improve photosensitivity.

  2. Observations of Ag diffusion in ion implanted SiC

    SciTech Connect

    Gerczak, Tyler J.; Leng, Bin; Sridharan, Kumar; Jerry L. Hunter, Jr.; Giordani, Andrew J.; Allen, Todd R.

    2015-03-17

    The nature and magnitude of Ag diffusion in SiC has been a topic of interest in connection with the performance of tristructural isotropic (TRISO) coated particle fuel for high temperature gas-cooled nuclear reactors. Ion implantation diffusion couples have been revisited to continue developing a more complete understanding of Ag fission product diffusion in SiC. Ion implantation diffusion couples fabricated from single crystal 4H-SiC and polycrystalline 3C-SiC substrates and exposed to 1500–1625°C, were investigated in this study by transmission electron microscopy and secondary ion mass spectrometry (SIMS). The high dynamic range of SIMS allowed for multiple diffusion régimes to be investigated, including enhanced diffusion by implantation-induced defects and grain boundary (GB) diffusion in undamaged SiC. Lastly, estimated diffusion coefficients suggest GB diffusion in bulk SiC does not properly describe the release observed from TRISO fuel.

  3. Very high energy implants of boron into silicon

    NASA Astrophysics Data System (ADS)

    La Ferla, A.; Rimini, E.; Ciavola, G.; Ferla, G.

    1989-02-01

    Boron ions of energy in the 15-50 MeV range and doses in the 10 13-10 15 cm -2 range were implanted into 1 kΩ cm n-type <100> silicon wafers. The samples, after annealing at 800-1250 ° C, were analyzed by spreading resistance profilometry. A simple model was used to predict the range distribution of the implanted ions. The measured projected ranges compare moderately well with calculations, while the concentration in the long tail up to the surface is two to three orders of magnitude higher than that calculated. Annealing at 1250 ° C for 24 h of multiple energy boron implants gives rise to a nearly flat profile with a concentration of 5 × 10 16 cm -3 over 100 μm. A diode with a junction depth of about 120 μm was realized.

  4. Implant bone integration importance in forensic identification.

    PubMed

    De Angelis, Danilo; Cattaneo, Cristina

    2015-03-01

    Odontological identification consists of the comparison of antemortem dental information regarding a missing person with postmortem data from an unidentified corpse or human remains. Usually, the comparison concerns morphologic features that the operator chooses among all the visible characteristics because of inter-individual uniqueness; for this reason, implants can be of enormous assistance. A case concerning the recovery of a burnt oral implant, connected to a bone fragment, among 2780 charred bone fragments, suspected to have belonged to a victim of homicide, is presented to demonstrate that dental implants and their site of bone integration represent a very precious element for personal forensic identification. Because of their morphological invariability in time and because of their morphologic uniqueness, they were used as evidence to associate unidentified human charred remains to a missing person where DNA analysis failed to do so. The case illustrates the fundamental contribution, not yet described in literature, given by the clinical aspects of tooth replacement with dental implants to a forensic discipline. Clinical practitioners should therefore be aware of the great importance of their work and of dental records in a forensic identification scenario. PMID:25387697

  5. [Cochlear implantation through the middle fossa approach].

    PubMed

    Szyfter, W; Colletti, V; Pruszewicz, A; Kopeć, T; Szymiec, E; Kawczyński, M; Karlik, M

    2001-01-01

    The inner part of cochlear implant is inserted into inner ear during surgery through mastoid and middle ear. It is a classical method, used in the majority cochlear centers in the world. This is not a suitable method in case of chronic otitis media and middle ear malformation. In these cases Colletti proposed the middle fossa approach and cochlear implant insertion omitting middle ear structures. In patient with bilateral chronic otitis media underwent a few ears operations without obtaining dry postoperative cavity. Cochlear implantation through the middle fossa approach was performed in this patient. The bone fenster was cut, temporal lobe was bent and petrosus pyramid upper surface was exposed. When the superficial petrosal greater nerve, facial nerve and arcuate eminence were localised, the cochlear was open in the basal turn and electrode were inserted. The patient achieves good results in the postoperative speech rehabilitation. It confirmed Colletti tesis that deeper electrode insertion in the cochlear implantation through the middle fossa approach enable use of low and middle frequencies, which are very important in speech understanding. PMID:11766315

  6. High energy implantation with high-charge-state ions in a vacuum arc ion implanter

    SciTech Connect

    Oks, E.M. |; Anders, A.; Brown, I.G.; Dickinson, M.R.; MacGill, R.A.

    1996-08-01

    Ion implantation energy can in principal be increased by increasing the charge states of the ions produced by the ion source rather than by increasing the implanter operating voltage, providing an important savings in cost and size of the implanter. In some recent work the authors have shown that the charge states of metal ions produced in a vacuum arc ion source can be elevated by a strong magnetic field. In general, the effect of both high arc current and high magnetic field is to push the distribution to higher charge states--the mean ion charge state is increased and new high charge states are formed. The effect is significant for implantation application--the mean ion energy can be about doubled without change in extraction voltage. Here they describe the ion source modifications, the results of time-of-flight measurements of ion charge state distributions, and discuss the use and implications of this technique as a means for doing metal iron implantation in the multi-hundreds of keV ion energy range.

  7. Typical whole body vibration exposure magnitudes encountered in the open pit mining industry.

    PubMed

    Howard, Bryan; Sesek, Richard; Bloswick, Don

    2009-01-01

    According to recent research, a causal link has been established between occupational exposure to whole body vibration and an increased occurrence of low back pain. To aid in the further development of an in-house health and safety program for a large open pit mining facility interested in reducing back pain among its operators, whole body vibration magnitudes were characterized for a range of jobs. Specifically, thirty-five individual jobs from five different areas across the facility were evaluated for tri-axial acceleration levels during normal operating conditions. Tri-axial acceleration magnitudes were categorized into thirteen job groups. Job groups were ranked according to exposure and compared to the ISO 2631-1 standard for health risk assessment. Three of the thirteen job groups produced tri-axial acceleration magnitudes below the ISO 2631-1 low/moderate health caution limit for a twelve hour exposure. Six of the thirteen job groups produced exposures within the moderate health risk range. Four job groups were found to subject operators to WBV acceleration magnitudes above the moderate/high health caution limit. PMID:20037244

  8. Spectral subtraction-based speech enhancement for cochlear implant patients in background noise

    NASA Astrophysics Data System (ADS)

    Yang, Li-Ping; Fu, Qian-Jie

    2005-03-01

    A single-channel speech enhancement algorithm utilizing speech pause detection and nonlinear spectral subtraction is proposed for cochlear implant patients in the present study. The spectral subtraction algorithm estimates the short-time spectral magnitude of speech by subtracting the estimated noise spectral magnitude from the noisy speech spectral magnitude. The artifacts produced by spectral subtraction (such as ``musical noise'') were significantly reduced by combining variance-reduced gain function and spectral flooring. Sentence recognition by seven cochlear implant subjects was tested under different noisy listening conditions (speech-shaped noise and 6-talker speech babble at +9, +6, +3, and 0 dB SNR) with and without the speech enhancement algorithm. For speech-shaped noise, performance for all subjects at all SNRs was significantly improved by the speech enhancement algorithm; for speech babble, performance was only modestly improved. The results suggest that the proposed speech enhancement algorithm may be beneficial for implant users in noisy listening. .

  9. Multiscale mapping of completeness magnitude of earthquake catalogs

    NASA Astrophysics Data System (ADS)

    Vorobieva, Inessa; Narteau, Clement; Shebalin, Peter; Beauducel, François; Nercessian, Alexandre; Clouard, Valérie; Bouin, Marie-Paule

    2013-04-01

    We propose a multiscale method to map spatial variations in completeness magnitude Mc of earthquake catalogs. The Mc value may significantly vary in space due to the change of the seismic network density. Here we suggest a way to use only earthquake catalogs to separate small areas of higher network density (lower Mc) and larger areas of smaller network density (higher Mc). We reduce the analysis of the FMDs to the limited magnitude ranges, thus allowing deviation of the FMD from the log-linearity outside the range. We associate ranges of larger magnitudes with increasing areas for data selection based on constant in average number of completely recorded earthquakes. Then, for each point in space, we document the earthquake frequency-magnitude distribution at all length scales within the corresponding earthquake magnitude ranges. High resolution of the Mc-value is achieved through the determination of the smallest space-magnitude scale in which the Gutenberg-Richter law (i. e. an exponential decay) is verified. The multiscale procedure isolates the magnitude range that meets the best local seismicity and local record capacity. Using artificial catalogs and earthquake catalogs of the Lesser Antilles arc, this Mc mapping method is shown to be efficient in regions with mixed types of seismicity, a variable density of epicenters and various levels of registration.

  10. Quantifying Heartbeat Dynamics by Magnitude and Sign Correlations

    NASA Astrophysics Data System (ADS)

    Ivanov, Plamen Ch.; Ashkenazy, Yosef; Kantelhardt, Jan W.; Stanley, H. Eugene

    2003-05-01

    We review a recently developed approach for analyzing time series with long-range correlations by decomposing the signal increment series into magnitude and sign series and analyzing their scaling properties. We show that time series with identical long-range correlations can exhibit different time organization for the magnitude and sign. We apply our approach to series of time intervals between consecutive heartbeats. Using the detrended fluctuation analysis method we find that the magnitude series is long-range correlated, while the sign series is anticorrelated and that both magnitude and sign series may have clinical applications. Further, we study the heartbeat magnitude and sign series during different sleep stages — light sleep, deep sleep, and REM sleep. For the heartbeat sign time series we find short-range anticorrelations, which are strong during deep sleep, weaker during light sleep and even weaker during REM sleep. In contrast, for the heartbeat magnitude time series we find long-range positive correlations, which are strong during REM sleep and weaker during light sleep. Thus, the sign and the magnitude series provide information which is also useful for distinguishing between different sleep stages.

  11. Induced earthquake magnitudes are as large as (statistically) expected

    NASA Astrophysics Data System (ADS)

    Elst, Nicholas J.; Page, Morgan T.; Weiser, Deborah A.; Goebel, Thomas H. W.; Hosseini, S. Mehran

    2016-06-01

    A major question for the hazard posed by injection-induced seismicity is how large induced earthquakes can be. Are their maximum magnitudes determined by injection parameters or by tectonics? Deterministic limits on induced earthquake magnitudes have been proposed based on the size of the reservoir or the volume of fluid injected. However, if induced earthquakes occur on tectonic faults oriented favorably with respect to the tectonic stress field, then they may be limited only by the regional tectonics and connectivity of the fault network. In this study, we show that the largest magnitudes observed at fluid injection sites are consistent with the sampling statistics of the Gutenberg-Richter distribution for tectonic earthquakes, assuming no upper magnitude bound. The data pass three specific tests: (1) the largest observed earthquake at each site scales with the log of the total number of induced earthquakes, (2) the order of occurrence of the largest event is random within the induced sequence, and (3) the injected volume controls the total number of earthquakes rather than the total seismic moment. All three tests point to an injection control on earthquake nucleation but a tectonic control on earthquake magnitude. Given that the largest observed earthquakes are exactly as large as expected from the sampling statistics, we should not conclude that these are the largest earthquakes possible. Instead, the results imply that induced earthquake magnitudes should be treated with the same maximum magnitude bound that is currently used to treat seismic hazard from tectonic earthquakes.

  12. Derivation of Johnson-Cousins Magnitudes from DSLR Camera Observations

    NASA Astrophysics Data System (ADS)

    Park, Woojin; Pak, Soojong; Shim, Hyunjin; Le, Huynh Anh N.; Im, Myungshin; Chang, Seunghyuk; Yu, Joonkyu

    2016-01-01

    The RGB Bayer filter system consists of a mosaic of R, G, and B filters on the grid of the photo sensors which typical commercial DSLR (Digital Single Lens Reflex) cameras and CCD cameras are equipped with. Lot of unique astronomical data obtained using an RGB Bayer filter system are available, including transient objects, e.g. supernovae, variable stars, and solar system bodies. The utilization of such data in scientific research requires that reliable photometric transformation methods are available between the systems. In this work, we develop a series of equations to convert the observed magnitudes in the RGB Bayer filter system (RB, GB, and BB) into the Johnson-Cousins BVR filter system (BJ, VJ, and RC). The new transformation equations derive the calculated magnitudes in the Johnson-Cousins filters (BJcal, VJcal, and RCcal) as functions of RGB magnitudes and colors. The mean differences between the transformed magnitudes and original magnitudes, i.e. the residuals, are (BJ - BJcal) = 0.064 mag, (VJ - VJcal) = 0.041 mag, and (RC - RCcal) = 0.039 mag. The calculated Johnson-Cousins magnitudes from the transformation equations show a good linear correlation with the observed Johnson-Cousins magnitudes.

  13. Prediction of implantable ECG lead systems by using thorax models.

    PubMed

    Vaisanen, J; Hyttinen, J; Puurtinen, M; Kauppinen, P; Malmivuo, J

    2004-01-01

    New implantable ECG devices may provide more stable and noiseless measurements compared to body surface ECG measurements. When the electrodes are moved to inside of the body the way the ECG measurement is done is changing. Modeling can be an effective way to study effects of implantation to the capacity of electrodes to measure ECG compared to surface measurements. This work introduces a project where effects of electrode implantation to the magnitude and direction of lead sensitivity to detect cardiac source, lead field, was studied with a model of the thorax as a volume conductor. The study was based on 3D finite difference method (FDM) featuring visible human man. The results of the study indicate that the effect of electrode implantation under the skin (5-15 mm) to the way they measure ECG is rather small. Magnitude change is dependent of the studied lead and the change of the sensitivity to heart's equivalent sources in direction of lead field is minor. PMID:17271800

  14. Regression between earthquake magnitudes having errors with known variances

    NASA Astrophysics Data System (ADS)

    Pujol, Jose

    2016-06-01

    Recent publications on the regression between earthquake magnitudes assume that both magnitudes are affected by error and that only the ratio of error variances is known. If X and Y represent observed magnitudes, and x and y represent the corresponding theoretical values, the problem is to find the a and b of the best-fit line y = a x + b. This problem has a closed solution only for homoscedastic errors (their variances are all equal for each of the two variables). The published solution was derived using a method that cannot provide a sum of squares of residuals. Therefore, it is not possible to compare the goodness of fit for different pairs of magnitudes. Furthermore, the method does not provide expressions for the x and y. The least-squares method introduced here does not have these drawbacks. The two methods of solution result in the same equations for a and b. General properties of a discussed in the literature but not proved, or proved for particular cases, are derived here. A comparison of different expressions for the variances of a and b is provided. The paper also considers the statistical aspects of the ongoing debate regarding the prediction of y given X. Analysis of actual data from the literature shows that a new approach produces an average improvement of less than 0.1 magnitude units over the standard approach when applied to Mw vs. mb and Mw vs. MS regressions. This improvement is minor, within the typical error of Mw. Moreover, a test subset of 100 predicted magnitudes shows that the new approach results in magnitudes closer to the theoretically true magnitudes for only 65 % of them. For the remaining 35 %, the standard approach produces closer values. Therefore, the new approach does not always give the most accurate magnitude estimates.

  15. Regression between earthquake magnitudes having errors with known variances

    NASA Astrophysics Data System (ADS)

    Pujol, Jose

    2016-07-01

    Recent publications on the regression between earthquake magnitudes assume that both magnitudes are affected by error and that only the ratio of error variances is known. If X and Y represent observed magnitudes, and x and y represent the corresponding theoretical values, the problem is to find the a and b of the best-fit line y = a x + b. This problem has a closed solution only for homoscedastic errors (their variances are all equal for each of the two variables). The published solution was derived using a method that cannot provide a sum of squares of residuals. Therefore, it is not possible to compare the goodness of fit for different pairs of magnitudes. Furthermore, the method does not provide expressions for the x and y. The least-squares method introduced here does not have these drawbacks. The two methods of solution result in the same equations for a and b. General properties of a discussed in the literature but not proved, or proved for particular cases, are derived here. A comparison of different expressions for the variances of a and b is provided. The paper also considers the statistical aspects of the ongoing debate regarding the prediction of y given X. Analysis of actual data from the literature shows that a new approach produces an average improvement of less than 0.1 magnitude units over the standard approach when applied to Mw vs. mb and Mw vs. MS regressions. This improvement is minor, within the typical error of Mw. Moreover, a test subset of 100 predicted magnitudes shows that the new approach results in magnitudes closer to the theoretically true magnitudes for only 65 % of them. For the remaining 35 %, the standard approach produces closer values. Therefore, the new approach does not always give the most accurate magnitude estimates.

  16. Force and movement of non-osseointegrated implants: an in vitro study.

    PubMed

    Flanagan, Dennis; Ilies, Horea; Lasko, Brian; Stack, Jeffrey

    2009-01-01

    Dental implants have enabled a dramatic increase in the quality of life for many partially edentulous and edentulous patents. Immediate loading of newly placed dental implants is a recent advancement that attempts to meet patient demand. However, immediate loading of a just placed implant may induce implant failure to osseointegrate. Some patients can generate a biting force that can reach approximately 1300 Newtons (N) in the posterior jaws. The magnitude of bite force that would cause failure of osseointegration of newly placed implants is currently unknown. It has been proposed that osseointegration would fail if an implant is luxated in bone more than 50 to 150 microns. Fibrous tissue, not bone, would form. This study investigated the quantity of various off-axial forces required to move a nonosseointegrated 4.3 x 13 mm implant 50 microns. The previously published pilot study for this study found that the amount of horizontal force required to displace an implant 50 microns was approximately 150 N. This study found that the force needed to move the implants 100 microns at a horizontal approach, 0 degrees, averaged 50 N, with a range of 23-79 N; at 22 degrees, averaged 52 N, with a range of 27-70 N; and at 60 degrees averaged 87 N, with a range of 33-105 N. PMID:20017642

  17. Comparison of magnetic probe calibration at nano and millitesla magnitudes

    NASA Astrophysics Data System (ADS)

    Pahl, Ryan A.; Rovey, Joshua L.; Pommerenke, David J.

    2014-01-01

    Magnetic field probes are invaluable diagnostics for pulsed inductive plasma devices where field magnitudes on the order of tenths of tesla or larger are common. Typical methods of providing a broadband calibration of dot{{B}} probes involve either a Helmholtz coil driven by a function generator or a network analyzer. Both calibration methods typically produce field magnitudes of tens of microtesla or less, at least three and as many as six orders of magnitude lower than their intended use. This calibration factor is then assumed constant regardless of magnetic field magnitude and the effects of experimental setup are ignored. This work quantifies the variation in calibration factor observed when calibrating magnetic field probes in low field magnitudes. Calibration of two dot{{B}} probe designs as functions of frequency and field magnitude are presented. The first dot{{B}} probe design is the most commonly used design and is constructed from two hand-wound inductors in a differential configuration. The second probe uses surface mounted inductors in a differential configuration with balanced shielding to further reduce common mode noise. Calibration factors are determined experimentally using an 80.4 mm radius Helmholtz coil in two separate configurations over a frequency range of 100-1000 kHz. A conventional low magnitude calibration using a vector network analyzer produced a field magnitude of 158 nT and yielded calibration factors of 15 663 ± 1.7% and 4920 ± 0.6% {T}/{V {s}} at 457 kHz for the surface mounted and hand-wound probes, respectively. A relevant magnitude calibration using a pulsed-power setup with field magnitudes of 8.7-354 mT yielded calibration factors of 14 615 ± 0.3% and 4507 ± 0.4% {T}/{V {s}} at 457 kHz for the surface mounted inductor and hand-wound probe, respectively. Low-magnitude calibration resulted in a larger calibration factor, with an average difference of 9.7% for the surface mounted probe and 12.0% for the hand-wound probe. The

  18. Prosthetic implant treatment of the edentulous maxilla with overdenture.

    PubMed

    Inversini, M

    2006-10-01

    The literature concerning the success of prosthetic implant treatment with maxillary overdenture is reviewed, and variables affecting treatment from the implant and prosthetic standpoint are analysed. Guidelines for the fabrication of maxillary overimplants comparable to those for mandibular overimplants are still lacking, as are evidence-based prosthetic design concepts. Individual methods and techniques have been described, but evaluation standards for the outcome of maxillary prosthetic-implant treatment are lacking or individually interpreted. The biomechanics involved in the proposed system are described, together with the advantages of telescopic crowns for the retention of removable partial prosthesis supported by maxillary implants. The positive influence, in terms of long-term prognosis, of the perio-protective design of removable partial prostheses supported by maxillary overimplants is also discussed. The proposed system not only provides stability, support and retention for removable partial prostheses supported by maxillary implants, but also enables implant survival rates to be improved, both for biomechanical reasons and due to improved oral hygiene. The simplification of fabrication procedures, repair, rebasing and re-operating also reduce the cost of follow-up and improve the cost/benefit ratio. However, additional studies are needed to clarify the number and most appropriate distribution of implants, as well as the most favourable prosthetic designs for maxillary overimplants. PMID:17268392

  19. Pediatric Cochlear Implantation: Why Do Children Receive Implants Late?

    PubMed Central

    Ham, Julia; Whittingham, JoAnne

    2015-01-01

    Objectives: Early cochlear implantation has been widely promoted for children who derive inadequate benefit from conventional acoustic amplification. Universal newborn hearing screening has led to earlier identification and intervention, including cochlear implantation in much of the world. The purpose of this study was to examine age and time to cochlear implantation and to understand the factors that affected late cochlear implantation in children who received cochlear implants. Design: In this population-based study, data were examined for all children who underwent cochlear implant surgery in one region of Canada from 2002 to 2013. Clinical characteristics were collected prospectively as part of a larger project examining outcomes from newborn hearing screening. For this study, audiologic details including age and severity of hearing loss at diagnosis, age at cochlear implant candidacy, and age at cochlear implantation were documented. Additional detailed medical chart information was extracted to identify the factors associated with late implantation for children who received cochlear implants more than 12 months after confirmation of hearing loss. Results: The median age of diagnosis of permanent hearing loss for 187 children was 12.6 (interquartile range: 5.5, 21.7) months, and the age of cochlear implantation over the 12-year period was highly variable with a median age of 36.2 (interquartile range: 21.4, 71.3) months. A total of 118 (63.1%) received their first implant more than 12 months after confirmation of hearing loss. Detailed analysis of clinical profiles for these 118 children revealed that late implantation could be accounted for primarily by progressive hearing loss (52.5%), complex medical conditions (16.9%), family indecision (9.3%), geographical location (5.9%), and other miscellaneous known (6.8%) and unknown factors (8.5%). Conclusions: This study confirms that despite the trend toward earlier implantation, a substantial number of children

  20. Piezosurgery in implant dentistry

    PubMed Central

    Stübinger, Stefan; Stricker, Andres; Berg, Britt-Isabelle

    2015-01-01

    Piezosurgery, or the use of piezoelectric devices, is being applied increasingly in oral and maxillofacial surgery. The main advantages of this technique are precise and selective cuttings, the avoidance of thermal damage, and the preservation of soft-tissue structures. Through the application of piezoelectric surgery, implant-site preparation, bone grafting, sinus-floor elevation, edentulous ridge splitting or the lateralization of the inferior alveolar nerve are very technically feasible. This clinical overview gives a short summary of the current literature and outlines the advantages and disadvantages of piezoelectric bone surgery in implant dentistry. Overall, piezoelectric surgery is superior to other methods that utilize mechanical instruments. Handling of delicate or compromised hard- and soft-tissue conditions can be performed with less risk for the patient. With respect to current and future innovative surgical concepts, piezoelectric surgery offers a wide range of new possibilities to perform customized and minimally invasive osteotomies. PMID:26635486

  1. Implants as absolute anchorage.

    PubMed

    Rungcharassaeng, Kitichai; Kan, Joseph Y K; Caruso, Joseph M

    2005-11-01

    Anchorage control is essential for successful orthodontic treatment. Each tooth has its own anchorage potential as well as propensity to move when force is applied. When teeth are used as anchorage, the untoward movements of the anchoring units may result in the prolonged treatment time, and unpredictable or less-than-ideal outcome. To maximize tooth-related anchorage, techniques such as differential torque, placing roots into the cortex of the bone, the use of various intraoral devices and/or extraoral appliances have been implemented. Implants, as they are in direct contact with bone, do not possess a periodontal ligament. As a result, they do not move when orthodontic/orthopedic force is applied, and therefore can be used as "absolute anchorage." This article describes different types of implants that have been used as orthodontic anchorage. Their clinical applications and limitations are also discussed. PMID:16463910

  2. Hormonal control of implantation.

    PubMed

    Sandra, Olivier

    2016-06-01

    In mammals, implantation represents a key step of pregnancy and its progression conditions not only the success of pregnancy but health of the offspring. Implantation requires a complex and specific uterine tissue, the endometrium, whose biological functions are tightly regulated by numerous signals, including steroids and polypeptide hormones. Endometrial tissue is endowed with dynamic properties that associate its ability to control the developmental trajectory of the embryo (driver property) and its ability to react to embryos displaying distinct capacities to develop to term (sensor property). Since dynamical properties of the endometrium can be affected by pre- and post-conceptional environment, determining how maternal hormonal signals and their biological actions are affected by environmental factors (e.g. nutrition, stress, infections) is mandatory to reduce or even to prevent their detrimental effects on endometrial physiology in order to preserve the optimal functionality of this tissue. PMID:27172870

  3. High Curie temperature drive layer materials for ion-implanted magnetic bubble devices

    NASA Technical Reports Server (NTRS)

    Fratello, V. J.; Wolfe, R.; Blank, S. L.; Nelson, T. J.

    1984-01-01

    Ion implantation of bubble garnets can lower the Curie temperature by 70 C or more, thus limiting high temperature operation of devices with ion-implanted propagation patterns. Therefore, double-layer materials were made with a conventional 2-micron bubble storage layer capped by an ion-implantable drive layer of high Curie temperature, high magnetostriction material. Contiguous disk test patterns were implanted with varying doses of a typical triple implant. Quality of propagation was judged by quasistatic tests on 8-micron period major and minor loops. Variations of magnetization, uniaxial anisotropy, implant dose, and magnetostriction were investigated to ensure optimum flux matching, good charged wall coupling, and wide operating margins. The most successful drive layer compositions were in the systems (SmDyLuCa)3(FeSi)5O12 and (BiGdTmCa)3(FeSi)5O12 and had Curie temperatures 25-44 C higher than the storage layers.

  4. Relationship between multipulse integration and speech recognition with cochlear implants

    PubMed Central

    Zhou, Ning; Pfingst, Bryan E.

    2014-01-01

    Comparisons of performance with cochlear implants and postmortem conditions in the cochlea in humans have shown mixed results. The limitations in those studies favor the use of within-subject designs and non-invasive measures to estimate cochlear conditions. One non-invasive correlate of cochlear health is multipulse integration, established in an animal model. The present study used this measure to relate neural health in human cochlear implant users to their speech recognition performance. The multipulse-integration slopes were derived based on psychophysical detection thresholds measured for two pulse rates (80 and 640 pulses per second). A within-subject design was used in eight subjects with bilateral implants where the direction and magnitude of ear differences in the multipulse-integration slopes were compared with those of the speech-recognition results. The speech measures included speech reception threshold for sentences and phoneme recognition in noise. The magnitude of ear difference in the integration slopes was significantly correlated with the magnitude of ear difference in speech reception thresholds, consonant recognition in noise, and transmission of place of articulation of consonants. These results suggest that multipulse integration predicts speech recognition in noise and perception of features that use dynamic spectral cues. PMID:25190399

  5. Miniature implantable ultrasonic echosonometer

    NASA Technical Reports Server (NTRS)

    Kojima, G. K. (Inventor)

    1978-01-01

    A miniature echosonometer adapted for implantation in the interior of an animal for imaging the internal structure of a organ, tissue or vessel is presented. The echosonometer includes a receiver/transmitter circuit which is coupled to an ultrasonic transducer. Power is coupled to the echosonometer by electromagnetic induction through the animal's skin. Imaging signals from the echosonometer are electromagnetically transmitted through the animal's skin to an external readout apparatus.

  6. Hip Resurfacing Implants.

    PubMed

    Cadossi, Matteo; Tedesco, Giuseppe; Sambri, Andrea; Mazzotti, Antonio; Giannini, Sandro

    2015-08-01

    EDUCATIONAL OBJECTIVES As a result of reading this article, physicians should be able to: 1. Describe the advantages of hip resurfacing. 2. Describe the disadvantages of hip resurfacing. 3. Identify the population in which hip resurfacing is most often indicated. 4. Demonstrate how to properly postoperatively manage patients with metal-on-metal prostheses. Hip resurfacing offers a suitable solution for young patients affected by hip disease who have high function demands and good bone quality. Bone stock preservation, restoration of the normal proximal femur anatomy, the lack of stress shielding, and the possibility of resuming sporting activity are proven advantages of hip resurfacing. However, there are some disadvantages, such as fracture of the femoral neck, onset of neck narrowing, and possible complications due to the metal-on-metal bearings, including pseudotumors, peri-implant osteolysis, and chronic elevation of metal ions in serum levels. Recent data suggest that the ideal candidate for hip resurfacing is an active male, younger than 65 years, with primary or posttraumatic osteoarthritis, and with a femoral head diameter larger than 50 to 54 mm. Based on these selection criteria, the literature reports implant survival to be similar to that of total hip arthroplasty. The current authors' experience confirms a low failure rate and excellent functional outcomes, with metal ion serum levels becoming stable over time in well-functioning implants. Proper surgical technique, correct patient selection, and the right choice of a well-established prosthetic model are essential elements for the long-term success of these implants. PMID:26270748

  7. Multi-objective control of nonlinear boiler-turbine dynamics with actuator magnitude and rate constraints.

    PubMed

    Chen, Pang-Chia

    2013-01-01

    This paper investigates multi-objective controller design approaches for nonlinear boiler-turbine dynamics subject to actuator magnitude and rate constraints. System nonlinearity is handled by a suitable linear parameter varying system representation with drum pressure as the system varying parameter. Variation of the drum pressure is represented by suitable norm-bounded uncertainty and affine dependence on system matrices. Based on linear matrix inequality algorithms, the magnitude and rate constraints on the actuator and the deviations of fluid density and water level are formulated while the tracking abilities on the drum pressure and power output are optimized. Variation ranges of drum pressure and magnitude tracking commands are used as controller design parameters, determined according to the boiler-turbine's operation range. PMID:22959740

  8. [Neurotology and cochlear implants].

    PubMed

    Merchán, Miguel A

    2015-05-01

    In this review we analyse cochlear implantation in terms of the fundamental aspects of the functioning of the auditory system. Concepts concerning neuronal plasticity applied to electrical stimulation in perinatal and adult deep hypoacusis are reviewed, and the latest scientific bases that justify early implantation following screening for congenital deafness are discussed. Finally, this review aims to serve as an example of the importance of fostering the sub-specialty of neurotology in our milieu, with the aim of bridging some of the gaps between specialties and thus improving both the knowledge in the field of research on auditory pathologies and in the screening of patients. The objectives of this review, targeted above all towards specialists in the field of otorhinolaryngology, are to analyse some significant neurological foundations in order to reach a better understanding of the clinical events that condition the indications and the rehabilitation of patients with cochlear implants, as well as to use this means to foster the growth of the sub-specialty of neurotology. PMID:25912703

  9. 3D finite element analysis of immediate loading of single wide versus double implants for replacing mandibular molar

    PubMed Central

    Desai, Shrikar R.; Karthikeyan, I.; Gaddale, Reetika

    2013-01-01

    Purpose: The purpose of this finite element study was to compare the stresses, strains, and displacements of double versus single implant in immediate loading for replacing mandibular molar. Materials and Methods: Two 3D FEM (finite element method) models were made to simulate implant designs. The first model used 5-mm-wide diameter implant to support a single molar crown. The second model used 3.75-3.75 double implant design. Anisotropic properties were assigned to bone model. Each model was analyzed with single force magnitude (100 N) in vertical axis. Results: This FEM study suggested that micromotion can be controlled better for double implants compared to single wide-diameter implants. The Von Mises stress for double implant showed 74.44% stress reduction compared to that of 5-mm implant. The Von Mises elastic strain was reduced by 61% for double implant compared to 5-mm implant. Conclusion: Within the limitations of the study, when the mesiodistal space for artificial tooth is more than 12.5 mm, under immediate loading, the double implant support should be considered. PMID:24554890

  10. A reevaluation of the 20-micron magnitude system

    NASA Technical Reports Server (NTRS)

    Tokunaga, A. T.

    1984-01-01

    The 20-micron infrared magnitude system is reexamined by observing primary infrared standards and seven A V stars. The purpose is to determine whether Alpha Lyr has colors consistent with the average of A0 stars and to determine the relative magnitude of the primary standards to that of Alpha Lyr. The data presented are consistent with the interpretation that the spectrum of Alpha Lyr is a blackbody and that it is a viable flux standard at 10 and 20 microns. The absolute flux density scale, the physical quantity of interest, is found to be consistent with an extrapolation of the Alpha Lyr spectrum from the near infrared on the basis of the comparison of stars to Mars and asteroids. Adoption of a 0.0 magnitude for Alpha Lyr requires that the magnitudes given by Morrison and Simon (1973) and by Simon et al. (1972) be revised downward by 0.14 mag.

  11. Number games, magnitude representation, and basic number skills in preschoolers.

    PubMed

    Whyte, Jemma Catherine; Bull, Rebecca

    2008-03-01

    The effect of 3 intervention board games (linear number, linear color, and nonlinear number) on young children's (mean age = 3.8 years) counting abilities, number naming, magnitude comprehension, accuracy in number-to-position estimation tasks, and best-fit numerical magnitude representations was examined. Pre- and posttest performance was compared following four 25-min intervention sessions. The linear number board game significantly improved children's performance in all posttest measures and facilitated a shift from a logarithmic to a linear representation of numerical magnitude, emphasizing the importance of spatial cues in estimation. Exposure to the number card games involving nonsymbolic magnitude judgments and association of symbolic and nonsymbolic quantities, but without any linear spatial cues, improved some aspects of children's basic number skills but not numerical estimation precision. PMID:18331146

  12. The Effects of Reinforcer Magnitude on Timing in Rats

    PubMed Central

    Ludvig, Elliot A; Conover, Kent; Shizgal, Peter

    2007-01-01

    The relation between reinforcer magnitude and timing behavior was studied using a peak procedure. Four rats received multiple consecutive sessions with both low and high levels of brain stimulation reward (BSR). Rats paused longer and had later start times during sessions when their responses were reinforced with low-magnitude BSR. When estimated by a symmetric Gaussian function, peak times also were earlier; when estimated by a better-fitting asymmetric Gaussian function or by analyzing individual trials, however, these peak-time changes were determined to reflect a mixture of large effects of BSR on start times and no effect on stop times. These results pose a significant dilemma for three major theories of timing (SET, MTS, and BeT), which all predict no effects for chronic manipulations of reinforcer magnitude. We conclude that increased reinforcer magnitude influences timing in two ways: through larger immediate after-effects that delay responding and through anticipatory effects that elicit earlier responding. PMID:17465312

  13. On the macroseismic magnitudes of the largest Italian earthquakes

    NASA Astrophysics Data System (ADS)

    Tinti, S.; Vittori, T.; Mulargia, F.

    1987-07-01

    The macroseismic magnitudes MT of the largest Italian earthquakes ( I0 ⩾ VIII, MCS) have been computed by using the intensity magnitude relationships recently assessed by the authors (1986) for the Italian region. The Progetto Finalizzato Geodinamica (PFG) catalog of the Italian earthquakes, covering the period 1000-1980 (Postpischl, 1985) is the source data base and is reproduced in the Appendix: here the estimated values of MT are given side by side with the catalog macroseismic magnitudes MK i.e. the magnitudes computed according to the Karnik laws (Karnik, 1969). The one-sigma errors Δ MT are also given for each earthquake. The basic aim of the paper is to provide a handy and useful tool to researchers involved in seismicity and seismic-risk studies on Italian territory.

  14. When Should Zero Be Included on a Scale Showing Magnitude?

    ERIC Educational Resources Information Center

    Kozak, Marcin

    2011-01-01

    This article addresses an important problem of graphing quantitative data: should one include zero on the scale showing magnitude? Based on a real time series example, the problem is discussed and some recommendations are proposed.

  15. Magnitude-frequency distribution of volcanic explosion earthquakes

    NASA Astrophysics Data System (ADS)

    Nishimura, Takeshi; Iguchi, Masato; Hendrasto, Mohammad; Aoyama, Hiroshi; Yamada, Taishi; Ripepe, Maurizio; Genco, Riccardo

    2016-07-01

    Magnitude-frequency distributions of volcanic explosion earthquakes that are associated with occurrences of vulcanian and strombolian eruptions, or gas burst activity, are examined at six active volcanoes. The magnitude-frequency distribution at Suwanosejima volcano, Japan, shows a power-law distribution, which implies self-similarity in the system, as is often observed in statistical characteristics of tectonic and volcanic earthquakes. On the other hand, the magnitude-frequency distributions at five other volcanoes, Sakurajima and Tokachi-dake in Japan, Semeru and Lokon in Indonesia, and Stromboli in Italy, are well explained by exponential distributions. The statistical features are considered to reflect source size, as characterized by a volcanic conduit or chamber. Earthquake generation processes associated with vulcanian, strombolian and gas burst events are different from those of eruptions ejecting large amounts of pyroclasts, since the magnitude-frequency distribution of the volcanic explosivity index is generally explained by the power law.

  16. Frequency-Magnitude Relationship of Hydraulic Fracture Microseismicity (Invited)

    NASA Astrophysics Data System (ADS)

    Maxwell, S.

    2009-12-01

    Microseismicity has become a common imaging technique for hydraulic fracture stimulations in the oil and gas industry, offering a wide range of microseismic data sets in different settings. Typically, arrays of 3C sensors are deployed in single monitoring wells presenting processing challenges associated with the limited acquisition geometry. However, the proximity of the sensors to the fracture network results in good sensitivity to detect small magnitude microseisms (down to about moment magnitude -3 in some cases). This sensitivity allows a comparison of the magnitude-frequency relationship between microseisms attributed to hydraulic fracturing with those related to activation of interaction with a pre-existing fault. A case study will be presented showing a clear change in the frequency-magnitude characteristics as the injection interacts with a known fault.

  17. Assessment of metal artefact reduction around dental titanium implants in cone beam CT

    PubMed Central

    Ibrahim, N; Hassan, B; Syriopoulos, K; van der Stelt, P

    2014-01-01

    Objectives: The aim of this study was to investigate if the metal artefact reduction (MAR) tool used in the software of the ORTHOPANTOMOGRAPH® OP300 (Instrumentarium Dental, Tuusula, Finland) can improve the gray value levels in post-operative implant scans. Methods: 20 potential implant sites were selected from 5 edentulous human dry mandibles. Each mandible was scanned by a CBCT scanner, and images were produced under three different conditions: implant sites drilled but no implants inserted, implants inserted without application of MAR and implants inserted with application of MAR. Using Geomagic® Studio 2012 (Geomagic, Morrisville, NC) and 3Diagnosys® v. 5.3.1 (3Diemme® SRL, Cantù, Italy) software, three scans of each mandible were superimposed. The mean gray value of identical regions of bone around the implants was derived for each condition. The differences between gray value measurements at implant sites derived from different conditions were assessed. Results: A significant difference was found between mean gray values from the scans with no implants inserted and with implants inserted (with and without MAR) (p = 0.012). No significant difference was revealed for gray values measured from scans with and without MAR (p = 0.975). Conclusions: The MAR tool in the software of the ORTHOPANTOMOGRAPH OP300 CBCT scanner does not significantly correct the voxel gray values affected by the metal artefact in the vicinity of an implant in human dry mandibles. PMID:25135316

  18. Bone attachment to glass-fibre-reinforced composite implant with porous surface.

    PubMed

    Mattila, R H; Laurila, P; Rekola, J; Gunn, J; Lassila, L V J; Mäntylä, T; Aho, A J; Vallittu, P K

    2009-06-01

    A method has recently been developed for producing fibre-reinforced composites (FRC) with porous surfaces, intended for use as load-bearing orthopaedic implants. This study focuses on evaluation of the bone-bonding behaviour of FRC implants. Three types of cylindrical implants, i.e. FRC implants with a porous surface, solid polymethyl methacrylate (PMMA) implants and titanium (Ti) implants, were inserted in a transverse direction into the intercondular trabeculous bone area of distal femurs and proximal tibias of New Zealand White rabbits. Animals were sacrificed at 3, 6 and 12 weeks post operation, and push-out tests (n=5-6 per implant type per time point) were then carried out. At 12 weeks the shear force at the porous FRC-bone interface was significantly higher (283.3+/-55.3N) than the shear force at interfaces of solid PMMA/bone (14.4+/-11.0 N; p<0.001) and Ti/bone (130.6+/-22.2N; p=0.001). Histological observation revealed new bone growth into the porous surface structure of FRC implants. Solid PMMA and Ti implants were encapsulated mostly with fibrous connective tissue. Finite element analysis (FEA) revealed that porous FRC implants had mechanical properties which could be tailored to smooth the shear stress distribution at the bone-implant interface and reduce the stress-shielding effect. PMID:19268643

  19. Possible sources of neuroprotection following subretinal silicon chip implantation in RCS rats

    NASA Astrophysics Data System (ADS)

    Pardue, Machelle T.; Phillips, Michael J.; Yin, Hang; Fernandes, Alcides; Cheng, Yian; Chow, Alan Y.; Ball, Sherry L.

    2005-03-01

    Current retinal prosthetics are designed to stimulate existing neural circuits in diseased retinas to create a visual signal. However, implantation of retinal prosthetics may create a neurotrophic environment that also leads to improvements in visual function. Possible sources of increased neuroprotective effects on the retina may arise from electrical activity generated by the prosthetic, mechanical injury due to surgical implantation, and/or presence of a chronic foreign body. This study evaluates these three neuroprotective sources by implanting Royal College of Surgeons (RCS) rats, a model of retinitis pigmentosa, with a subretinal implant at an early stage of photoreceptor degeneration. Treatment groups included rats implanted with active and inactive devices, as well as sham-operated. These groups were compared to unoperated controls. Evaluation of retinal function throughout an 18 week post-implantation period demonstrated transient functional improvements in eyes implanted with an inactive device at 6, 12 and 14 weeks post-implantation. However, the number of photoreceptors located directly over or around the implant or sham incision was significantly increased in eyes implanted with an active or inactive device or sham-operated. These results indicate that in the RCS rat localized neuroprotection of photoreceptors from mechanical injury or a chronic foreign body may provide similar results to subretinal electrical stimulation at the current output evaluated here.

  20. Absolute magnitudes and phase coefficients of trans-Neptunian objects

    NASA Astrophysics Data System (ADS)

    Alvarez-Candal, A.; Pinilla-Alonso, N.; Ortiz, J. L.; Duffard, R.; Morales, N.; Santos-Sanz, P.; Thirouin, A.; Silva, J. S.

    2016-02-01

    Context. Accurate measurements of diameters of trans-Neptunian objects (TNOs) are extremely difficult to obtain. Thermal modeling can provide good results, but accurate absolute magnitudes are needed to constrain the thermal models and derive diameters and geometric albedos. The absolute magnitude, HV, is defined as the magnitude of the object reduced to unit helio- and geocentric distances and a zero solar phase angle and is determined using phase curves. Phase coefficients can also be obtained from phase curves. These are related to surface properties, but only few are known. Aims: Our objective is to measure accurate V-band absolute magnitudes and phase coefficients for a sample of TNOs, many of which have been observed and modeled within the program "TNOs are cool", which is one of the Herschel Space Observatory key projects. Methods: We observed 56 objects using the V and R filters. These data, along with those available in the literature, were used to obtain phase curves and measure V-band absolute magnitudes and phase coefficients by assuming a linear trend of the phase curves and considering a magnitude variability that is due to the rotational light-curve. Results: We obtained 237 new magnitudes for the 56 objects, six of which were without previously reported measurements. Including the data from the literature, we report a total of 110 absolute magnitudes with their respective phase coefficients. The average value of HV is 6.39, bracketed by a minimum of 14.60 and a maximum of -1.12. For the phase coefficients we report a median value of 0.10 mag per degree and a very large dispersion, ranging from -0.88 up to 1.35 mag per degree.

  1. Application of confocal laser microscopy for monitoring mesh implants in herniology

    SciTech Connect

    Zakharov, V P; Belokonev, V I; Bratchenko, I A; Timchenko, P E; Vavilov, A V; Volova, L T

    2011-04-30

    The state of the surface of mesh implants and their encapsulation region in herniology is investigated by laser confocal microscopy. A correlation between the probability of developing relapses and the size and density of implant microdefects is experimentally shown. The applicability limits of differential reverse scattering for monitoring the post-operation state of implant and adjacent tissues are established based on model numerical experiments. (optical technologies in biophysics and medicine)

  2. Short implants: are they a viable option in implant dentistry?

    PubMed

    Schwartz, Steven Richard

    2015-04-01

    Short-length implants (<10 mm) can be used effectively in atrophic maxillae or mandibles even with crown/implant ratios that previously would have been considered excessive. Short implants can support either single or multiple units and can be used for fixed prostheses or overdentures. The use of short-length implants may avoid the need for complicated bone augmentation procedures, thus allowing patients who were either unwilling or unable for financial or medical reasons to undergo these advanced grafting techniques to be adequately treated. PMID:25835796

  3. Magnitude knowledge: the common core of numerical development.

    PubMed

    Siegler, Robert S

    2016-05-01

    The integrated theory of numerical development posits that a central theme of numerical development from infancy to adulthood is progressive broadening of the types and ranges of numbers whose magnitudes are accurately represented. The process includes four overlapping trends: (1) representing increasingly precisely the magnitudes of non-symbolic numbers, (2) connecting small symbolic numbers to their non-symbolic referents, (3) extending understanding from smaller to larger whole numbers, and (4) accurately representing the magnitudes of rational numbers. The present review identifies substantial commonalities, as well as differences, in these four aspects of numerical development. With both whole and rational numbers, numerical magnitude knowledge is concurrently correlated with, longitudinally predictive of, and causally related to multiple aspects of mathematical understanding, including arithmetic and overall math achievement. Moreover, interventions focused on increasing numerical magnitude knowledge often generalize to other aspects of mathematics. The cognitive processes of association and analogy seem to play especially large roles in this development. Thus, acquisition of numerical magnitude knowledge can be seen as the common core of numerical development. PMID:27074723

  4. A probabilistic neural network for earthquake magnitude prediction.

    PubMed

    Adeli, Hojjat; Panakkat, Ashif

    2009-09-01

    A probabilistic neural network (PNN) is presented for predicting the magnitude of the largest earthquake in a pre-defined future time period in a seismic region using eight mathematically computed parameters known as seismicity indicators. The indicators considered are the time elapsed during a particular number (n) of significant seismic events before the month in question, the slope of the Gutenberg-Richter inverse power law curve for the n events, the mean square deviation about the regression line based on the Gutenberg-Richter inverse power law for the n events, the average magnitude of the last n events, the difference between the observed maximum magnitude among the last n events and that expected through the Gutenberg-Richter relationship known as the magnitude deficit, the rate of square root of seismic energy released during the n events, the mean time or period between characteristic events, and the coefficient of variation of the mean time. Prediction accuracies of the model are evaluated using three different statistical measures: the probability of detection, the false alarm ratio, and the true skill score or R score. The PNN model is trained and tested using data for the Southern California region. The model yields good prediction accuracies for earthquakes of magnitude between 4.5 and 6.0. The PNN model presented in this paper complements the recurrent neural network model developed by the authors previously, where good results were reported for predicting earthquakes with magnitude greater than 6.0. PMID:19502005

  5. High-orbit satellite magnitude estimation using photometric measurement method

    NASA Astrophysics Data System (ADS)

    Zhang, Shixue

    2015-12-01

    The means to get the accurate high-orbit satellite magnitude can be significant in space target surveillance. This paper proposes a satellite photometric measurement method based on image processing. We calculate the satellite magnitude by comparing the output value of camera's CCD between the known fixed star and the satellite. We calculate the luminance value of a certain object on the acquired image using a background-removing method. According to the observation parameters such as azimuth, elevation, height and the situation of the telescope, we can draw the star map on the image, so we can get the real magnitude of a certain fixed star in the image. We derive a new method to calculate the magnitude value of a certain satellite according to the magnitude of the fixed star in the image. To guarantee the algorithm's stability, we evaluate the measurement precision of the method, and analysis the restrict condition in actual application. We have made plenty of experiment of our system using large telescope in satellite surveillance, and testify the correctness of the algorithm. The experimental result shows that the precision of the proposed algorithm in satellite magnitude measurement is 0.24mv, and this method can be generalized to other relative fields.

  6. Cochlear implantation in a patient with grand mal epilepsy.

    PubMed

    Szilvassy, J; Czigner, J; Somogyi, I; Jori, J; Kiss, J G; Szilvassy, Z

    1998-06-01

    A case is reported in which a Nucleus 22 channel intracochlear implant was used to treat a deaf Hungarian woman (aged 37 years) with a 34-year history of grand mal (GM) epilepsy maintained on carbamazepine-diazepam combination therapy who had not benefited from conventional hearing aids. Pre-operative electrical stimulation of the acoustic nerve, however, exhibited a good nerve function with no evidence of abnormal waveforms in the electroencephalogram (EEG). Successful intracochlear insertion of the 22 electrode resulted in a 40 dB hearing improvement at frequencies 250-2000 Hz in the implanted ear with no signs of pathologic wave activity at either the previously recognized epileptic focus (fronto-precentral region) or indeed, in other regions of the brain at use of the implant. We conclude that intracochlear implantation per se is not a hazardous intervention in patients with fronto-precentral epileptic foci. PMID:9764299

  7. Phosphorus implantation into 4H-silicon carbide

    SciTech Connect

    Capano, M.A.; Santhakumar, R.; Venugopal, R.; Melloch, M.R.; Cooper, J.A. Jr.

    2000-02-01

    Sheet resistances in nitrogen- and phosphorus-implanted 4H-SiC are measured to assess the time and temperature dependencies of this variable. In 4H-SiC implanted with 3 x 10{sup 15} cm{sup {minus}2} nitrogen ions to a depth of 2,800 {angstrom}, the minimum sheet resistance observed is 534 {Omega}/{open{underscore}square}, a record low value for any implanted element into any polytype of SiC. Time-independent sheet resistances are observed following anneals at 1,700 C for nitrogen and phosphorus samples. Lower temperature anneals produce sheet resistances which decrease monotonically with increasing time of anneal. Overall, sheet resistances from phosphorus-implanted 4H-SiC are an order of magnitude below those measured from nitrogen implanted samples. The response of phosphorus to low-temperature annealing is significant, and sheet resistances below 500 {Omega}/{open{underscore}square} are achieved at 1,200 C. Activation of phosphorus is attempted in an oxidizing atmosphere with and without prior argon annealing. A three-hour gate oxidation in wet O{sub 2} at 1,150 C, followed by a 30 min argon anneal, produced a sheet resistance of 1081 {Omega}/{open{underscore}square}. Oxidation after argon annealing caused sheet resistances to increase by about 20% compared to samples subjected solely to argon annealing. It is also found that oxide growth rates are much higher over phosphorus implanted than over unimplanted 4H-SiC. Reasons for the disparity in sheet resistances between nitrogen and phosphorus implants, and for the difference in oxide growth rates are suggested.

  8. Optical image storage in ion implanted PLZT ceramics

    SciTech Connect

    Peercy, P. S.; Land, C. E.

    1980-01-01

    Optical images can be stored in transparent lead-lanthanum-zirconate-titanate (PLZT) ceramics by exposure to near-uv light with photon energies greater than the band gas energy of approx. 3.35 eV. The image storage process relies on optically induced changes in the switching properties of ferroelectric domains (photoferroelectric effect). Stored images are nonvolatile but can be erased by uniform uv illumination and simultaneous application of an electric field. Although high quality images, with contrast variations of greater than or equal to 100:1 and spatial resolution of approx. 10 ..mu..m, can be stored using the photoferroelectric effect, relatively high exposure energies (approx. 100 mJ/cm/sup 2/) are required to store these images. This large exposure energy severely limits the range of possible applications of nonvolatile image storage in PLZT ceramics. It was found in H, He, and Ar implanted PLZT that the photosensitivity can be significantly increased by ion implantation into the surface to be exposed. The photosensitivity after implantation with 5 x 10/sup 14/ 500 keV Ar/cm/sup 2/ is increased by about three orders of magnitude over that of unimplanted PLZT. The image storage process and the effect of ion implantation is presented along with a phenomenological model which describes the enhancement in photosensitivity obtained by ion implantation. This model takes into account both light- and ion implantation-induced changes in conductivity and gives quantitative agreement with the measured changes in the coercive voltage with light intensity for ion implanted PLZT.

  9. Diluted magnetic semiconductor effects in Mn-implanted silicon carbide

    SciTech Connect

    Komarov, A. V.; Ryabchenko, S. M.; Los, A. V.; Romanenko, S. M.

    2011-04-15

    Light transmission and Faraday rotation spectra measured at the temperature of 2 K were compared for silicon carbide single crystals of 4H polytype (4H-SiC), implanted with 3.8 x 10{sup 16} cm{sup -2} of Mn ions at the beam energy of 190 keV, and a control 4H-SiC single crystal sample, which was not implanted. Mn ion implantation led to the creation of a Mn-doped surface layer with the average Mn concentration of 10{sup 21} cm{sup -3} and a thickness of approximately 0.2 {mu}m. Transmission of light through the implanted crystal changed only slightly in comparison with the control sample, which however, corresponded to a relatively strong attenuation in the implanted layer. This was interpreted as a result of scattering, which emerges in the surface layer due to optical nonuniformities, created by the high energy ion irradiation. The presence of a thin Mn-ion-containing surface layer led, despite its small thickness, to noticeable changes in the sample Faraday rotation spectra. The estimated values of the Verdet constant for this layer were about three orders of magnitude larger and of opposite sign compared to the Verdet constant values of the undoped sample. Magnetic field dependencies of the Faraday rotation contribution from the implanted layer were found to be saturating functions, which points to a proportionality of the Faraday rotation to the magnetization of the paramagnetic Mn ion subsystem. Based on these findings we conclude that the Mn-implanted SiC layer exhibits magneto-optical properties typical of a diluted magnetic semiconductor. At the same time, no ferromagnetic ordering was observed in the studied (Si, Mn)C sample.

  10. [Actuality with the breast implants].

    PubMed

    Duchateau, J

    2013-09-01

    The author presents the history of breast implants, and the modern evolution where breast implants are largely used in both cosmetic and reconstructive surgery. Breast augmentation is one of the most performed cosmetic procedures, with a high satisfaction rate. However, one needs to remind that breast implants have a limited duration of life. The estimated rate of breast implant rupture after 10 years is of 10% in the current literature, This rate will probably become lower with the new more cohesive implants recently available on the market. It is therefore essential to propose a regular follow-up to all patients having breast implants. This follow-up is performed using a combination of physical examination, mammograms, ultrasound and MRI. The more specific therapeutic approach for patients having a PIP prosthesis will also be discussed. PMID:24195240

  11. Estimation of the magnitudes and epicenters of Philippine historical earthquakes

    NASA Astrophysics Data System (ADS)

    Bautista, Maria Leonila P.; Oike, Kazuo

    2000-02-01

    The magnitudes and epicenters of Philippine earthquakes from 1589 to 1895 are estimated based on the review, evaluation and interpretation of historical accounts and descriptions. The first step involves the determination of magnitude-felt area relations for the Philippines for use in the magnitude estimation. Data used were the earthquake reports of 86, recent, shallow events with well-described effects and known magnitude values. Intensities are assigned according to the modified Mercalli intensity scale of I to XII. The areas enclosed by Intensities III to IX [ A(III) to A(IX)] are measured and related to magnitude values. The most robust relations are found for magnitudes relating to A(VI), A(VII), A(VIII) and A(IX). Historical earthquake data are obtained from primary sources in libraries in the Philippines and Spain. Most of these accounts were made by Spanish priests and officials stationed in the Philippines during the 15th to 19th centuries. More than 3000 events are catalogued, interpreted and their intensities determined by considering the possible effects of local site conditions, type of construction and the number and locations of existing towns to assess completeness of reporting. Of these events, 485 earthquakes with the largest number of accounts or with at least a minimum report of damage are selected. The historical epicenters are estimated based on the resulting generalized isoseismal maps augmented by information on recent seismicity and location of known tectonic structures. Their magnitudes are estimated by using the previously determined magnitude-felt area equations for recent events. Although historical epicenters are mostly found to lie on known tectonic structures, a few, however, are found to lie along structures that show not much activity during the instrumented period. A comparison of the magnitude distributions of historical and recent events showed that only the period 1850 to 1900 may be considered well-reported in terms of

  12. Positron Implantation Profile in Kapton

    NASA Astrophysics Data System (ADS)

    Dryzek, J.; Dryzek, E.

    2006-11-01

    The discussion presented in the paper focuses on processes accompanying positron implantation in condensed matter. They finally constitute the positron implantation profile which generally does not exhibit the exponential behavior as it is concluded from the Monte Carlo simulation made using the EGSnrc 4.0 code. The simulation was performed for the kapton and two commonly used positron sources 22Na and 68Ge\\68Ga. New formula for the implantation profile was proposed.

  13. [Pre-implant esthetic study].

    PubMed

    Missika, P; Khayat, P

    1990-09-01

    The first dental prostheses used on Branemark implants were aesthetically disappointing both for the dentists and their patients. Therefore the authors will consider the various aesthetic problems encountered when treating loss of teeth with implant systems. The problems related to resorption are numerous: large bone losses are resolved by adapting removable acrylic, carrying out bone transplants immediately fixed by the implants, using filling materials, or complete dentures fixed with attachments supported by the implants. Periodontal surgery often provides a solution to the problem of gum visibility at the level of the maxillary anterior teeth. The problems related to the site where implants emerge can often be avoided by consultation between the surgeon and the prosthodontist and by flexing a surgical guide compiled from a pre-prosthetic analysis of the clinical situation. The aesthetic problems related to the actual implant systems are dependent on three factors: When the prosthesis is directly screwed onto the implant, the axis of the implant determines the axis of the dental prosthesis and can lead to the emergence of the screw on the buccal surface; With angulated cores, orientated screws provide the required solution. The implant material, when metallic leads to an unsightly border at the gingival level. Ceramic implants, or the "ceraming" of titanium, provide a solution to this problem. In case of diastema the use of an implant system gives the best choice in comparison to the more conventional treatments. In conclusion, the authors point out the importance of pre-implant analysis which must give an evaluation of the aesthetic result. The fragility of the aesthetic evaluation should encourage dentists to obtain the "clear and written consent" of their patients, accepting the risks run by treatment of this kind. PMID:2268774

  14. Smart polymers for implantable electronics

    NASA Astrophysics Data System (ADS)

    Ware, Taylor H.

    Neural interfaces have been heavily investigated due to their unique ability to tap into the communication system of the body. Substrates compatible with microelectronics processing are planar and 5-7 orders of magnitude stiffer than the tissue with which they interact. This work enables fabrication of devices by photolithography that are stiff enough to penetrate soft tissue, change in stiffness to more closely match the modulus of tissue after implantation and adopt shapes to conform to tissue. Several classes of physiologically-responsive, amorphous polymer networks with the onset of the glass transition above 37 °C are synthesized and thermomechanically characterized. These glassy networks exhibit an isothermal reduction in modulus due to plasticization in the presence of aqueous fluids. Modulus after plasticization can be tuned by the dry glass transition temperature, degree of plasticization and crosslink density. Acrylic shape memory polymer based intracortical probes, which can change in modulus from above 1 GPa to less than 1 MPa, are fabricated through a transfer process that shields the substrate from processing and enhances adhesion to the microelectronics. Substrates capable of withstanding the conditions of photolithography are fabricated "thiol-ene" and "thiol-epoxy" substrates. These materials provide processing windows that rival engineering thermoplastics, swell less than 6% in water, and exhibit a controllable reduction in modulus from above 1 GPa to between 5 and 150 MPa. Substrates, planar for processing, that subsequently recover 3D shapes are synthesized by the formation of post-gelation crosslinks either covalent or supramolecular in nature. Acrylics with varied supramolecular, based on ureidopyrimidone moieties, and covalent crosslink density demonstrate triple-shape memory behavior. Post-gelation covalent crosslinks are established to permanently fix 3D shapes in thiol-ene networks. Devices fabricated include intracortical and nerve cuff

  15. Practical ways to reduce radiation dose for patients and staff during device implantations and electrophysiological procedures.

    PubMed

    Heidbuchel, Hein; Wittkampf, Fred H M; Vano, Eliseo; Ernst, Sabine; Schilling, Richard; Picano, Eugenio; Mont, Lluis; Jais, Pierre; de Bono, Joseph; Piorkowski, Christopher; Saad, Eduardo; Femenia, Francisco

    2014-07-01

    Despite the advent of non-fluoroscopic technology, fluoroscopy remains the cornerstone of imaging in most interventional electrophysiological procedures, from diagnostic studies over ablation interventions to device implantation. Moreover, many patients receive additional X-ray imaging, such as cardiac computed tomography and others. More and more complex procedures have the risk to increase the radiation exposure, both for the patients and the operators. The professional lifetime attributable excess cancer risk may be around 1 in 100 for the operators, the same as for a patient undergoing repetitive complex procedures. Moreover, recent reports have also hinted at an excess risk of brain tumours among interventional cardiologists. Apart from evaluating the need for and justifying the use of radiation to assist their procedures, physicians have to continuously explore ways to reduce the radiation exposure. After an introduction on how to quantify the radiation exposure and defining its current magnitude in electrophysiology compared with the other sources of radiation, this position paper wants to offer some very practical advice on how to reduce exposure to patients and staff. The text describes how customization of the X-ray system, workflow adaptations, and shielding measures can be implemented in the cath lab. The potential and the pitfalls of different non-fluoroscopic guiding technologies are discussed. Finally, we suggest further improvements that can be implemented by both the physicians and the industry in the future. We are confident that these suggestions are able to reduce patient and operator exposure by more than an order of magnitude, and therefore think that these recommendations are worth reading and implementing by any electrophysiological operator in the field. PMID:24792380

  16. Stress Analysis on Single Cobalt/Chrome Prosthesis With a 15-mm Cantilever Placed Over 10/13/15-mm-length Implants: A Simulated Photoelastic Model Study.

    PubMed

    Gastaldo, José Fábio Guastelli; Pimentel, Angélica Castro; Gomes, Maria Helena; Sendyk, Wilson Roberto; Laganá, Dalva Cruz

    2015-12-01

    The aim of study was to assess the stress around 10/13/15-mm implants in the mandibular area with a 15-mm cantilevered acrylic-resin-coated prostheses following the application force, using the photoelasticity method. Three photoelastic mandibular models were created containing 10-, 13-, and 15-mm implants in length and 3.75 mm in diameter. The implants had bore internal hex connections and were placed parallel to the intermental region. Abutments with 1-mm high cuffs were placed over the implants, and a single cobalt/chrome metallic prosthesis with a 15-mm cantilever, coated with thermoplastic acrylic resin, was placed on top. Loads of 1.0 and 3.0 bars were applied, and the images were photographed and assessed by photoelasticity method. The greatest stress levels were observed for the 10-mm implants. The stress pattern was the same regardless of implant length; only the magnitude of the stress along the implant body revealed changes. Increased implant length played a role in reducing stress on the investigated area of the model, and the 15-mm implants exhibited the best performance in regard to stress distribution. The highest stress levels were found in the implants closest to the cantilever and the central implant. The longest implants were more favorable in regard to the stress distribution on the peri-implant support structures in the 15-mm cantilevered prosthesis under loads. PMID:24914673

  17. International Classification of Reliability for Implanted Cochlear Implant Receiver Stimulators

    PubMed Central

    Battmer, Rolf-Dieter; Backous, Douglas D.; Balkany, Thomas J.; Briggs, Robert J. S.; Gantz, Bruce J.; van Hasselt, Andrew; Kim, Chong Sun; Kubo, Takeshi; Lenarz, Thomas; Pillsbury, Harold C.; O’Donoghue, Gerard M.

    2016-01-01

    Objective To design an international standard to be used when reporting reliability of the implanted components of cochlear implant systems to appropriate governmental authorities, cochlear implant (CI) centers, and for journal editors in evaluating manuscripts involving cochlear implant reliability. Study Design The International Consensus Group for Cochlear Implant Reliability Reporting was assembled to unify ongoing efforts in the United States, Europe, Asia, and Australia to create a consistent and comprehensive classification system for the implanted components of CI systems across manufacturers. Setting All members of the consensus group are from tertiary referral cochlear implant centers. Interventions None. Main Outcome Measure A clinically relevant classification scheme adapted from principles of ISO standard 5841-2:2000 (1) originally designed for reporting reliability of cardiac pacemakers, pulse generators, or leads. Results Standard definitions for device failure, survival time, clinical benefit, reduced clinical benefit, and specification were generated. Time intervals for reporting back to implant centers for devices tested to be “out of specification,” categorization of explanted devices, the method of cumulative survival reporting, and content of reliability reports to be issued by manufacturers was agreed upon by all members. The methodology for calculating Cumulative survival was adapted from ISO standard 5841-2:2000 (1). Conclusion The International Consensus Group on Cochlear Implant Device Reliability Reporting recommends compliance to this new standard in reporting reliability of implanted CI components by all manufacturers of CIs and the adoption of this standard as a minimal reporting guideline for editors of journals publishing cochlear implant research results. PMID:20864879

  18. Induced earthquake magnitudes are as large as (statistically) expected

    NASA Astrophysics Data System (ADS)

    van der Elst, N.; Page, M. T.; Weiser, D. A.; Goebel, T.; Hosseini, S. M.

    2015-12-01

    Key questions with implications for seismic hazard and industry practice are how large injection-induced earthquakes can be, and whether their maximum size is smaller than for similarly located tectonic earthquakes. Deterministic limits on induced earthquake magnitudes have been proposed based on the size of the reservoir or the volume of fluid injected. McGarr (JGR 2014) showed that for earthquakes confined to the reservoir and triggered by pore-pressure increase, the maximum moment should be limited to the product of the shear modulus G and total injected volume ΔV. However, if induced earthquakes occur on tectonic faults oriented favorably with respect to the tectonic stress field, then they may be limited only by the regional tectonics and connectivity of the fault network, with an absolute maximum magnitude that is notoriously difficult to constrain. A common approach for tectonic earthquakes is to use the magnitude-frequency distribution of smaller earthquakes to forecast the largest earthquake expected in some time period. In this study, we show that the largest magnitudes observed at fluid injection sites are consistent with the sampling statistics of the Gutenberg-Richter (GR) distribution for tectonic earthquakes, with no assumption of an intrinsic upper bound. The GR law implies that the largest observed earthquake in a sample should scale with the log of the total number induced. We find that the maximum magnitudes at most sites are consistent with this scaling, and that maximum magnitude increases with log ΔV. We find little in the size distribution to distinguish induced from tectonic earthquakes. That being said, the probabilistic estimate exceeds the deterministic GΔV cap only for expected magnitudes larger than ~M6, making a definitive test of the models unlikely in the near future. In the meantime, however, it may be prudent to treat the hazard from induced earthquakes with the same probabilistic machinery used for tectonic earthquakes.

  19. Implant biomaterials: A comprehensive review

    PubMed Central

    Saini, Monika; Singh, Yashpal; Arora, Pooja; Arora, Vipin; Jain, Krati

    2015-01-01

    Appropriate selection of the implant biomaterial is a key factor for long term success of implants. The biologic environment does not accept completely any material so to optimize biologic performance, implants should be selected to reduce the negative biologic response while maintaining adequate function. Every clinician should always gain a thorough knowledge about the different biomaterials used for the dental implants. This article makes an effort to summarize various dental bio-materials which were used in the past and as well as the latest material used now. PMID:25610850

  20. Graphene synthesis by ion implantation

    NASA Astrophysics Data System (ADS)

    Garaj, Slaven; Hubbard, William; Golovchenko, J. A.

    2010-11-01

    We demonstrate an ion implantation method for large-scale synthesis of high quality graphene films with controllable thickness. Thermally annealing polycrystalline nickel substrates that have been ion implanted with carbon atoms results in the surface growth of graphene films whose average thickness is controlled by implantation dose. The graphene film quality, as probed with Raman and electrical measurements, is comparable to previously reported synthesis methods. The implantation synthesis method can be generalized to a variety of metallic substrates and growth temperatures, since it does not require a decomposition of chemical precursors or a solvation of carbon into the substrate.

  1. Graphene synthesis by ion implantation.

    PubMed

    Garaj, Slaven; Hubbard, William; Golovchenko, J A

    2010-11-01

    We demonstrate an ion implantation method for large-scale synthesis of high quality graphene films with controllable thickness. Thermally annealing polycrystalline nickel substrates that have been ion implanted with carbon atoms results in the surface growth of graphene films whose average thickness is controlled by implantation dose. The graphene film quality, as probed with Raman and electrical measurements, is comparable to previously reported synthesis methods. The implantation synthesis method can be generalized to a variety of metallic substrates and growth temperatures, since it does not require a decomposition of chemical precursors or a solvation of carbon into the substrate. PMID:21124725

  2. Implantable medical devices MRI safe.

    PubMed

    Dal Molin, Renzo; Hecker, Bertrand

    2013-01-01

    Pacemakers, ICDs, neurostimulators like deep brain stimulator electrodes, spiral cord stimulators, insulin pumps, cochlear implants, retinal implants, hearing aids, electro cardio gram (ECG) leads, or devices in interventional MRI such as vascular guide wires or catheters are affected by MRI magnetic and electromagnetic fields. Design of MRI Safe medical devices requires computer modeling, bench testing, phantom testing, and animal studies. Implanted medical devices can be MRI unsafe, MRI conditional or MRI safe (see glossary). In the following paragraphs we will investigate how to design implanted medical devices MRI safe. PMID:23739365

  3. Graphene synthesis by ion implantation

    PubMed Central

    Garaj, Slaven; Hubbard, William; Golovchenko, J. A.

    2010-01-01

    We demonstrate an ion implantation method for large-scale synthesis of high quality graphene films with controllable thickness. Thermally annealing polycrystalline nickel substrates that have been ion implanted with carbon atoms results in the surface growth of graphene films whose average thickness is controlled by implantation dose. The graphene film quality, as probed with Raman and electrical measurements, is comparable to previously reported synthesis methods. The implantation synthesis method can be generalized to a variety of metallic substrates and growth temperatures, since it does not require a decomposition of chemical precursors or a solvation of carbon into the substrate. PMID:21124725

  4. Age-Dependent Cost-Utility of Pediatric Cochlear Implantation

    PubMed Central

    Semenov, Yevgeniy R.; Yeh, Susan T.; Seshamani, Meena; Wang, Nae-Yuh; Tobey, Emily A.; Eisenberg, Laurie S.; Quittner, Alexandra L.; Frick, Kevin D.; Niparko, John K.

    2013-01-01

    Objective Cochlear implantation has become the mainstay of treatment for children with severe-to-profound sensorineural hearing loss (SNHL). Yet, despite mounting evidence on the clinical benefits of early implantation, little data are available on the long-term societal benefits and comparative effectiveness of this procedure across various ages of implantation--a choice parameter for parents and clinicians with high prognostic value for clinical outcome. As such, the aim of the current study is to evaluate a model of the consequences of the timing of this intervention from a societal economic perspective. Average cost-utility of pediatric cochlear implantation by age at intervention will be analyzed. Design Prospective, longitudinal assessment of health-utility and educational placement outcomes in 175 children recruited from 6 US centers between November 2002 and December 2004, who had severe-to-profound SNHL onset within 1 year of age, underwent cochlear implantation before 5 years of age, and had up to 6 years of post-implant follow-up that ended in November 2008 to December 2011. Costs of care were collected retrospectively and stratified by pre-operative, operative, and post-operative expenditures. Incremental costs and benefits of implantation were compared between the three age groups and relative to a non-implantation baseline. Results Children implanted at <18 months of age gained an average of 10.7 QALYs over their projected lifetime as compared to 9.0 and 8.4 QALYs for those implanted between 18 and 36 months and at >36 months of age, respectively. Medical and surgical complication rates were not significantly different between the 3 age groups. Additionally, mean lifetime costs of implantation were similar between the 3 groups, at approximately $2,000/child/year (77.5 year life expectancy), yielding costs of $14,996, $17,849, and $19,173 per QALY for the youngest, middle, and oldest implant age groups, respectively. Full mainstream classroom

  5. Magnitude Characterization Using Complex Networks in Central Chile

    NASA Astrophysics Data System (ADS)

    Pasten, D.; Comte, D.; Munoz, V.

    2013-12-01

    Studies using complex networks are applied to many systems, like traffic, social networks, internet and earth science. In this work we make an analysis using complex networks applied to magnitude of seismicity in the central zone of Chile, we use the preferential attachment in order to construct a seismic network using local magnitudes and the hypocenters of a seismic data set in central Chile. In order to work with a complete catalogue in magnitude, the data associated with the linear part of the Gutenberg-Richter law, with magnitudes greater than 2.7, were taken. We then make a grid in space, so that each seismic event falls into a certain cell, depending on the location of its hypocenter. Now the network is constructed: the first node corresponds to the cell where the first seismic event occurs. The node has an associated number which is the magnitude of the event which occured in it, and a probability is assigned to the node. The probability is a nonlinear mapping of the magnitude (a Gaussian function was taken), so that nodes with lower magnitude events are more likely to be attached to. Each time a new node is added to the network, it is attached to the previous node which has the larger probability; the link is directed from the previous node to the new node. In this way, a directed network is constructed, with a ``preferential attachment''-like growth model, using the magnitudes as the parameter to determine the probability of attachment to future nodes. Several events could occur in the same node. In this case, the probability is calculated using the average of the magnitudes of the events occuring in that node. Once the directed network is finished, the corresponding undirected network is constructed, by making all links symmetric, and eliminating the loops which may appear when two events occur in the same cell. The resulting directed network is found to be scale free (with very low values of the power-law distribution exponent), whereas the undirected

  6. Zero Magnitude Effect for the Productivity of Triggered Tsunami Sources

    NASA Astrophysics Data System (ADS)

    Geist, E. L.

    2013-12-01

    The Epidemic Type Aftershock Sequence (ETAS) model is applied to tsunami events to explain previously observed temporal clustering of tsunami sources. Tsunami events are defined by National Geophysical Data Center (NGDC) tsunami database. For the ETAS analysis, the earthquake magnitude associated with each tsunami event in the NGDC database is replaced by the primary magnitude listed in the Centennial catalog up until 1976 and in the Global CMT catalog from 1976 through 2010. Tsunamis with a submarine landslide or volcanic component are included if they are accompanied by an earthquake, which is most often the case. Tsunami size is used as a mark for determining a tsunami-generating event, according to a minimum completeness level. The tsunami catalog is estimated to be complete for tsunami sizes greater than 1 m since 1900 and greater than 0.1 m since 1960. Of the five parameters in the temporal ETAS model (Ogata, 1988), the parameter that scales the magnitude dependence in the productivity of triggered events is the one that is most different from ETAS parameters derived from similar earthquake catalogs. Maximum likelihood estimates of this magnitude effect parameter is essentially zero, within 95% confidence, for both the 0.1 m and 1.0 m tsunami completeness levels. To explain this result, parameter estimates are determined for the Global CMT catalog under three tsunamigenic conditions: (1) M≥7 and focal depth ≤50 km, (2) submarine location, and (3) dominant component of dip slip. Successive subcatalogs are formed from the Global CMT catalog according to each of these conditions. The high magnitude threshold for tsunamigenesis alone (subcatalog 1) does not explain the zero magnitude effect. The zero magnitude effect also does not appear to be caused the smaller number of tsunamigenic events analyzed in comparison to earthquake catalogs with a similar magnitude threshold. ETAS parameter estimates from the subcatalog (3) with all three tsunamigenic conditions

  7. The Strain Energy, Seismic Moment and Magnitudes of Large Earthquakes

    NASA Astrophysics Data System (ADS)

    Purcaru, G.

    2004-12-01

    The strain energy Est, as potential energy, released by an earthquake and the seismic moment Mo are two fundamental physical earthquake parameters. The earthquake rupture process ``represents'' the release of the accumulated Est. The moment Mo, first obtained in 1966 by Aki, revolutioned the quantification of earthquake size and led to the elimination of the limitations of the conventional magnitudes (originally ML, Richter, 1930) mb, Ms, m, MGR. Both Mo and Est, not in a 1-to-1 correspondence, are uniform measures of the size, although Est is presently less accurate than Mo. Est is partitioned in seismic- (Es), fracture- (Eg) and frictional-energy Ef, and Ef is lost as frictional heat energy. The available Est = Es + Eg (Aki and Richards (1980), Kostrov and Das, (1988) for fundamentals on Mo and Est). Related to Mo, Est and Es, several modern magnitudes were defined under various assumptions: the moment magnitude Mw (Kanamori, 1977), strain energy magnitude ME (Purcaru and Berckhemer, 1978), tsunami magnitude Mt (Abe, 1979), mantle magnitude Mm (Okal and Talandier, 1987), seismic energy magnitude Me (Choy and Boatright, 1995, Yanovskaya et al, 1996), body-wave magnitude Mpw (Tsuboi et al, 1998). The available Est = (1/2μ )Δ σ Mo, Δ σ ~=~average stress drop, and ME is % \\[M_E = 2/3(\\log M_o + \\log(\\Delta\\sigma/\\mu)-12.1) ,\\] % and log Est = 11.8 + 1.5 ME. The estimation of Est was modified to include Mo, Δ and μ of predominant high slip zones (asperities) to account for multiple events (Purcaru, 1997): % \\[E_{st} = \\frac{1}{2} \\sum_i {\\frac{1}{\\mu_i} M_{o,i} \\Delta\\sigma_i} , \\sum_i M_{o,i} = M_o \\] % We derived the energy balance of Est, Es and Eg as: % \\[ E_{st}/M_o = (1+e(g,s)) E_s/M_o , e(g,s) = E_g/E_s \\] % We analyzed a set of about 90 large earthquakes and found that, depending on the goal these magnitudes quantify differently the rupture process, thus providing complementary means of earthquake characterization. Results for some

  8. Deep photometry and integral magnitudes of 8 nearby galaxies

    NASA Astrophysics Data System (ADS)

    Georgiev, Ts. B.

    2016-02-01

    We estimated integral magnitudes of galaxies trying to include the contribution of the brightest part of their halos. We performed surface photometry based on (i) concentric elliptical rims, corresponding to the peripheral ellipticity of the image, (ii) median estimation of the mean value of the rim pixels, (iii) apparent radial brightness profiles, corresponding to the rim medians, and (iv) magnitude curves of growth, derived by numerical integrations of the apparent rim profiles, without preliminary background estimation and removal. Furthermore, we used the magnitude curves of growth to determine the integral magnitudes (limited by size and deepness of our frames) and compared them with the total magnitudes in the data base HyperLeda. Also, we used the rim-profiles to estimate the background level far enough from the galaxy center and we build (here—only for trial) the intrinsic radial profiles (with background removal). We apply this photometry on 8 nearby galaxies, observed with CCD in the system BVRC IC by the 50 cm Schmidt telescope of the Rozhen NAO in 2003-2004. We build radial profiles which occur to be as average 1.8 times (1.2-2.5 times) larger than in data base NED and of integral brightness that occurs to be about 1.4 times (1.2-1.7 times) higher than in data base HyperLeda. The relative brightness additions, found here, correlate with the color index and anti-correlate with the luminosity of the galaxy.

  9. Correlating Total Visual Magnitude Estimates and CCD Photometry for Comets

    NASA Astrophysics Data System (ADS)

    Kidger, Mark Richard

    2015-08-01

    A key facet of understanding the activity of comets is coverage of their light curve. For some comets such as 2P/Encke there is good light curve coverage from visual observers extending back over many returns over more than 2 centuries. However, in recent years, CCD photometry by amateur astronomers has become the dominant data source and the number of total visual magnitude estimates has reduced sharply, making comparison of recent and historical photometric data for comets increasingly difficult. The relationship between total visual magnitude estimates - dominated by the emission from the Swan bands of C2 - and CCD aperture photometry - dominated by the dust continuum - has been far from clear.This paper compares CCD aperture photometry and total visual magnitude for several recent well-observed bright comets, including C/2014 Q2 (Lovejoy), C/2012 S1 (ISON) and C/2011 L4 (PanSTARRS) using a consistent and homogeneous database of observations from (mainly) Spanish observers. For comets with a 1/r radial coma profile, good agreement is found between CCD aperture photometry and total visual magnitude estimates for a CCD aperture corresponding to a physical coma diameter of ≈105km.The relationship between the coma radial brightness slope and the equivalent physical aperture for CCD photometry to obtain agreement with total visual magnitude estimates is investigated.

  10. Magnitude and phase behavior of multiresolution BOLD signal

    PubMed Central

    Chen, Zikuan; Calhoun, Vince D.

    2010-01-01

    High spatial resolution fMRI provides a more precise estimate of brain activity than low resolution fMRI. The magnitude and phase parts of the BOLD signals are impacted differently by changes in the scan resolution. In this paper, we report on a numerical simulation to show the impact of spatial resolution upon the complex-valued BOLD signal in terms of magnitude and phase variation. We generate realistic capillary networks in cortex voxels, calculate the BOLD-induced magnetic field disturbance and the complex BOLD signals for the voxel and its subvoxels, and thereby characterize the magnitude and phase behaviors across multiple grid resolutions. Our results show that: 1) at higher spatial resolution there is greater spatial variation in the phase of the BOLD signal as compared to its magnitude; 2) the spatial variation of the phase signal monotonically increases with respect to spatial resolution while for the magnitude the spatial variation may reach a maximum at some resolution level; 3) voxels containing large capillaries have higher phase spatial variation than those with smaller capillaries; 4) the amplitude spatial variation at a resolution level increases with respect to relaxation time whereas the phase variation is generally unaffected. PMID:20890375

  11. Magnitude of perceived depth of multiple stereo transparent surfaces.

    PubMed

    Aida, Saori; Shimono, Koichi; Tam, Wa James

    2015-01-01

    According to the geometric relational expression of binocular stereopsis, for a given viewing distance the magnitude of the perceived depth of objects would be the same, as long as the disparity magnitudes were the same. However, we found that this is not necessarily the case for random-dot stereograms that depict parallel, overlapping, transparent stereoscopic surfaces (POTS). The data from five experiments indicated that (1) the magnitude of perceived depth between the two outer surfaces of a three- or a four-POTS configuration can be smaller than that for an identical pair of stereo surfaces of a two-POTS configuration for the range of disparities that we used (5.2-19.4 arcmin); (2) this phenomenon can be observed irrespective of the total dot density of a POTS configuration, at least for the range that we used (1.1-3.3 dots/deg(2)); and (3) the magnitude of perceived depth between the two outer surfaces of a POTS configuration can be reduced as the total number of stereo surfaces is increased, up to four surfaces. We explained these results in terms of a higher-order process or processes, with an output representing perceived depth magnitude, which is weakened when the number of its surfaces is increased. PMID:25120178

  12. Frictional coefficients of ion-implanted alumina against ion-implanted beta-titanium in the low load, low velocity, single pass regime.

    PubMed

    Kusy, R P; Tobin, E J; Whitley, J Q; Sioshansi, P

    1992-05-01

    The frictional coefficients were measured for four wire alloys against the flats of polycrystalline alumina cylinders using a low load, low velocity, single pass device. Ion-implantations of titanium into polycrystalline alumina flats and nitrogen into beta-titanium wires reduced the static and kinetic coefficients from 0.50 and 0.44 before implantation to 0.20 and 0.25 after implantation, respectively. These results are similar in magnitude to frictional coefficients for unimplanted, control couples of stainless steel, cobalt-chromium, and nickel titanium wires against polycrystalline alumina flats. For orthodontic applications, we conclude that more efficient and reproducible appliances can be engineered for tooth movement if ion-implantation is used to reduce the abrasion of beta-titanium by polycrystalline alumina. PMID:1521704

  13. The Current Testing Protocols for Biomechanical Evaluation of Lumbar Spinal Implants in Laboratory Setting: A Review of the Literature

    PubMed Central

    Gonzalez-Blohm, Sabrina A.; Doulgeris, James J.; Lee, William E.; Shea, Thomas M.; Vrionis, Frank D.

    2015-01-01

    In vitro biomechanical investigations have become a routinely employed technique to explore new lumbar instrumentation. One of the most important advantages of such investigations is the low risk present when compared to clinical trials. However, the best use of any experimental data can be made when standard testing protocols are adopted by investigators, thus allowing comparisons among studies. Experimental variables, such as the length of the specimen, operative level, type of loading (e.g., dynamic versus quasistatic), magnitude, and rate of load applied, are among the most common variables controlled during spinal biomechanical testing. Although important efforts have been made to standardize these protocols, high variability can be found in the current literature. The aim of this investigation was to conduct a systematic review of the literature to identify the current trends in the protocols reported for the evaluation of new lumbar spinal implants under laboratory setting. PMID:25785272

  14. Implantable medical sensor system

    DOEpatents

    Darrow, Christopher B.; Satcher, Jr., Joe H.; Lane, Stephen M.; Lee, Abraham P.; Wang, Amy W.

    2001-01-01

    An implantable chemical sensor system for medical applications is described which permits selective recognition of an analyte using an expandable biocompatible sensor, such as a polymer, that undergoes a dimensional change in the presence of the analyte. The expandable polymer is incorporated into an electronic circuit component that changes its properties (e.g., frequency) when the polymer changes dimension. As the circuit changes its characteristics, an external interrogator transmits a signal transdermally to the transducer, and the concentration of the analyte is determined from the measured changes in the circuit. This invention may be used for minimally invasive monitoring of blood glucose levels in diabetic patients.

  15. Broad beam ion implanter

    DOEpatents

    Leung, Ka-Ngo

    1996-01-01

    An ion implantation device for creating a large diameter, homogeneous, ion beam is described, as well as a method for creating same, wherein the device is characterized by extraction of a diverging ion beam and its conversion by ion beam optics to an essentially parallel ion beam. The device comprises a plasma or ion source, an anode and exit aperture, an extraction electrode, a divergence-limiting electrode and an acceleration electrode, as well as the means for connecting a voltage supply to the electrodes.

  16. Broad beam ion implanter

    DOEpatents

    Leung, K.N.

    1996-10-08

    An ion implantation device for creating a large diameter, homogeneous, ion beam is described, as well as a method for creating same, wherein the device is characterized by extraction of a diverging ion beam and its conversion by ion beam optics to an essentially parallel ion beam. The device comprises a plasma or ion source, an anode and exit aperture, an extraction electrode, a divergence-limiting electrode and an acceleration electrode, as well as the means for connecting a voltage supply to the electrodes. 6 figs.

  17. [Implantation of the zygote].

    PubMed

    Hicks Gómez, J J

    1990-01-01

    In order for implantation to occur, the endometrium must be adequately differentiated, a estate which results from the sequential interaction of progesterone and estrogens, and the local effects of prostaglandins and histamine. Nevertheless, the exact mechanism through which these hormones affect the uterus is not clearly understood. Recently it has been proposed the role of second messengers (cAMP.cGMP, inositol triphosphate and diacylglycerol) in this process. All these messengers are related with the intracellular mechanisms of proteic and steroid hormones action. PMID:2177440

  18. Virtual estimates of fastening strength for pedicle screw implantation procedures

    NASA Astrophysics Data System (ADS)

    Linte, Cristian A.; Camp, Jon J.; Augustine, Kurt E.; Huddleston, Paul M.; Robb, Richard A.; Holmes, David R.

    2014-03-01

    Traditional 2D images provide limited use for accurate planning of spine interventions, mainly due to the complex 3D anatomy of the spine and close proximity of nerve bundles and vascular structures that must be avoided during the procedure. Our previously developed clinician-friendly platform for spine surgery planning takes advantage of 3D pre-operative images, to enable oblique reformatting and 3D rendering of individual or multiple vertebrae, interactive templating, and placement of virtual pedicle implants. Here we extend the capabilities of the planning platform and demonstrate how the virtual templating approach not only assists with the selection of the optimal implant size and trajectory, but can also be augmented to provide surrogate estimates of the fastening strength of the implanted pedicle screws based on implant dimension and bone mineral density of the displaced bone substrate. According to the failure theories, each screw withstands a maximum holding power that is directly proportional to the screw diameter (D), the length of the in-bone segm,ent of the screw (L), and the density (i.e., bone mineral density) of the pedicle body. In this application, voxel intensity is used as a surrogate measure of the bone mineral density (BMD) of the pedicle body segment displaced by the screw. We conducted an initial assessment of the developed platform using retrospective pre- and post-operative clinical 3D CT data from four patients who underwent spine surgery, consisting of a total of 26 pedicle screws implanted in the lumbar spine. The Fastening Strength of the planned implants was directly assessed by estimating the intensity - area product across the pedicle volume displaced by the virtually implanted screw. For post-operative assessment, each vertebra was registered to its homologous counterpart in the pre-operative image using an intensity-based rigid registration followed by manual adjustment. Following registration, the Fastening Strength was computed

  19. Absolute magnitude calibration using trigonometric parallax - Incomplete, spectroscopic samples

    NASA Technical Reports Server (NTRS)

    Ratnatunga, Kavan U.; Casertano, Stefano

    1991-01-01

    A new numerical algorithm is used to calibrate the absolute magnitude of spectroscopically selected stars from their observed trigonometric parallax. This procedure, based on maximum-likelihood estimation, can retrieve unbiased estimates of the intrinsic absolute magnitude and its dispersion even from incomplete samples suffering from selection biases in apparent magnitude and color. It can also make full use of low accuracy and negative parallaxes and incorporate censorship on reported parallax values. Accurate error estimates are derived for each of the fitted parameters. The algorithm allows an a posteriori check of whether the fitted model gives a good representation of the observations. The procedure is described in general and applied to both real and simulated data.

  20. The magnitude distribution of declustered earthquakes in Southern California

    PubMed Central

    Knopoff, Leon

    2000-01-01

    The binned distribution densities of magnitudes in both the complete and the declustered catalogs of earthquakes in the Southern California region have two significantly different branches with crossover magnitude near M = 4.8. In the case of declustered earthquakes, the b-values on the two branches differ significantly from each other by a factor of about two. The absence of self-similarity across a broad range of magnitudes in the distribution of declustered earthquakes is an argument against the application of an assumption of scale-independence to models of main-shock earthquake occurrence, and in turn to the use of such models to justify the assertion that earthquakes are unpredictable. The presumption of scale-independence for complete local earthquake catalogs is attributable, not to a universal process of self-organization leading to future large earthquakes, but to the universality of the process that produces aftershocks, which dominate complete catalogs. PMID:11035770

  1. Executive function and magnitude skills in preschool children.

    PubMed

    Prager, Emily O; Sera, Maria D; Carlson, Stephanie M

    2016-07-01

    Executive function (EF) has been highlighted as a potentially important factor for mathematical understanding. The relation has been well established in school-aged children but has been less explored at younger ages. The current study investigated the relation between EF and mathematics in preschool-aged children. Participants were 142 typically developing 3- and 4-year-olds. Controlling for verbal ability, a significant positive correlation was found between EF and general math abilities in this age group. Importantly, we further examined this relation causally by varying the EF load on a magnitude comparison task. Results suggested a developmental pattern where 3-year-olds' performance on the magnitude comparison task was worst when EF was taxed the most. Conversely, 4-year-olds performed well on the magnitude task despite varying EF demands, suggesting that EF might play a critical role in the development of math concepts. PMID:27082019

  2. Every reinforcer counts: reinforcer magnitude and local preference.

    PubMed Central

    Davison, Michael; Baum, William M

    2003-01-01

    Six pigeons were trained on concurrent variable-interval schedules. Sessions consisted of seven components, each lasting 10 reinforcers, with the conditions of reinforcement differing between components. The component sequence was randomly selected without replacement. In Experiment 1, the concurrent-schedule reinforcer ratios in components were all equal to 1.0, but across components reinforcer-magnitude ratios varied from 1:7 through 7:1. Three different overall reinforcer rates were arranged across conditions. In Experiment 2, the reinforcer-rate ratios varied across components from 27:1 to 1:27, and the reinforcer-magnitude ratios for each alternative were changed across conditions from 1:7 to 7:1. The results of Experiment 1 replicated the results for changing reinforcer-rate ratios across components reported by Davison and Baum (2000, 2002): Sensitivity to reinforcer-magnitude ratios increased with increasing numbers of reinforcers in components. Sensitivity to magnitude ratio, however, fell short of sensitivity to reinforcer-rate ratio. The degree of carryover from component to component depended on the reinforcer rate. Larger reinforcers produced larger and longer postreinforcer preference pulses than did smaller reinforcers. Similar results were found in Experiment 2, except that sensitivity to reinforcer magnitude was considerably higher and was greater for magnitudes that differed more from one another. Visit durations following reinforcers measured either as number of responses emitted or time spent responding before a changeover were longer following larger than following smaller reinforcers, and were longer following sequences of same reinforcers than following other sequences. The results add to the growing body of research that informs model building at local levels. PMID:13677611

  3. The use of stress analysis methods to evaluate the biomechanics of oral rehabilitation with implants.

    PubMed

    Pesqueira, Aldiéris; Goiato, Marcelo; Gennari-Filho, Humberto; Monteiro, Douglas; Dos Santos, Daniela; Haddad, Marcela; Pellizzer, Eduardo

    2012-03-01

    Abstract Because the biomechanical behavior of dental implants is different from that of natural tooth, clinical problems may occur. The mechanism of stress distribution and load transfer to the implant/bone interface is a critical issue affecting the success rate of implants. Therefore, the aim of this study was to conduct a brief literature review about the available stress analysis methods to study implant-supported prosthesis loading, and to discuss their contributions in the biomechanical evaluation of oral rehabilitation with implants. It was found that several studies have used experimental, analytical and computational models by means of finite element models (FEM), photoelasticity, strain gauges and associations of these methods to evaluate the biomechanical behavior of dental implants. The FEM has been used to evaluate new components, configurations, materials and shape of implants. The greatest advantage of the photoelastic method is the ability to visualize the stresses in complex structures such as oral structures, and to observe the stress patterns in the whole model, allowing to localize and to quantify the stress magnitude. The strain gauges can be used to assess in vivo and in vitro stress in prosthesis, implants and teeth. Some authors use the strain gauge technique associated with either photoelasticity or FEM techniques. These methodologies can be widely applied in Dentistry, mainly in the research field. Therefore, they can guide further researches and clinical studies by predicting some disadvantages and streamlining the clinical time. PMID:22380838

  4. Use of stress analysis methods to evaluate the biomechanics of oral rehabilitation with implants.

    PubMed

    Pesqueira, Aldiéris Alves; Goiato, Marcelo Coelho; Filho, Humberto Gennari; Monteiro, Douglas Roberto; Santos, Daniela Micheline Dos; Haddad, Marcela Filié; Pellizzer, Eduardo Piza

    2014-04-01

    Because the biomechanical behavior of dental implants is different from that of natural tooth, clinical problems may occur. The mechanism of stress distribution and load transfer to the implant/bone interface is a critical issue affecting the success rate of implants. Therefore, the aim of this study was to conduct a brief literature review of the available stress analysis methods to study implant-supported prosthesis loading and to discuss their contributions in the biomechanical evaluation of oral rehabilitation with implants. Several studies have used experimental, analytical, and computational models by means of finite element models (FEM), photoelasticity, strain gauges and associations of these methods to evaluate the biomechanical behavior of dental implants. The FEM has been used to evaluate new components, configurations, materials, and shapes of implants. The greatest advantage of the photoelastic method is the ability to visualize the stresses in complex structures, such as oral structures, and to observe the stress patterns in the whole model, allowing the researcher to localize and quantify the stress magnitude. Strain gauges can be used to assess in vivo and in vitro stress in prostheses, implants, and teeth. Some authors use the strain gauge technique with photoelasticity or FEM techniques. These methodologies can be widely applied in dentistry, mainly in the research field. Therefore, they can guide further research and clinical studies by predicting some disadvantages and streamlining clinical time. PMID:24779954

  5. Convex optimization of MRI exposure for mitigation of RF-heating from active medical implants.

    PubMed

    Córcoles, Juan; Zastrow, Earl; Kuster, Niels

    2015-09-21

    Local RF-heating of elongated medical implants during magnetic resonance imaging (MRI) may pose a significant health risk to patients. The actual patient risk depends on various parameters including RF magnetic field strength and frequency, MR coil design, patient's anatomy, posture, and imaging position, implant location, RF coupling efficiency of the implant, and the bio-physiological responses associated with the induced local heating. We present three constrained convex optimization strategies that incorporate the implant's RF-heating characteristics, for the reduction of local heating of medical implants during MRI. The study emphasizes the complementary performances of the different formulations. The analysis demonstrates that RF-induced heating of elongated metallic medical implants can be carefully controlled and balanced against MRI quality. A reduction of heating of up to 25 dB can be achieved at the cost of reduced uniformity in the magnitude of the B(1)(+) field of less than 5%. The current formulations incorporate a priori knowledge of clinically-specific parameters, which is assumed to be available. Before these techniques can be applied practically in the broader clinical context, further investigations are needed to determine whether reduced access to a priori knowledge regarding, e.g. the patient's anatomy, implant routing, RF-transmitter, and RF-implant coupling, can be accepted within reasonable levels of uncertainty. PMID:26350025

  6. Toward Reconciling Magnitude Discrepancies Estimated from Paleoearthquake Data

    SciTech Connect

    N. Seth Carpenter; Suzette J. Payne; Annette L. Schafer

    2012-06-01

    We recognize a discrepancy in magnitudes estimated for several Basin and Range, U.S.A. faults. For example, magnitudes predicted for the Wasatch (Utah), Lost River (Idaho), and Lemhi (Idaho) faults from fault segment lengths (L{sub seg}) where lengths are defined between geometrical, structural, and/or behavioral discontinuities assumed to persistently arrest rupture, are consistently less than magnitudes calculated from displacements (D) along these same segments. For self-similarity, empirical relationships (e.g. Wells and Coppersmith, 1994) should predict consistent magnitudes (M) using diverse fault dimension values for a given fault (i.e. M {approx} L{sub seg}, should equal M {approx} D). Typically, the empirical relationships are derived from historical earthquake data and parameter values used as input into these relationships are determined from field investigations of paleoearthquakes. A commonly used assumption - grounded in the characteristic-earthquake model of Schwartz and Coppersmith (1984) - is equating L{sub seg} with surface rupture length (SRL). Many large historical events yielded secondary and/or sympathetic faulting (e.g. 1983 Borah Peak, Idaho earthquake) which are included in the measurement of SRL and used to derive empirical relationships. Therefore, calculating magnitude from the M {approx} SRL relationship using L{sub seg} as SRL leads to an underestimation of magnitude and the M {approx} L{sub seg} and M {approx} D discrepancy. Here, we propose an alternative approach to earthquake magnitude estimation involving a relationship between moment magnitude (Mw) and length, where length is L{sub seg} instead of SRL. We analyze seven historical, surface-rupturing, strike-slip and normal faulting earthquakes for which segmentation of the causative fault and displacement data are available and whose rupture included at least one entire fault segment, but not two or more. The preliminary Mw {approx} L{sub seg} results are strikingly consistent

  7. Numerical simulation of in vivo intraosseous torsional failure of a hollow-screw oral implant

    PubMed Central

    Cehreli, Murat; Akkocaoglu, Murat; Akca, Kivanc

    2006-01-01

    Background Owing to the complexity and magnitude of functional forces transferred to the bone-implant interface, the mechanical strength of the interface is of great importance. The purpose of this study was to determine the intraosseous torsional shear strength of an osseointegrated oral implant using 3-D finite element (FE) stress analysis implemented by in vivo failure torque data of an implant. Methods A Ø 3.5 mm × 12 mm ITI® hollow screw dental implant in a patient was subjected to torque failure test using a custom-made strain-gauged manual torque wrench connected to a data acquisition system. The 3-D FE model of the implant and peri-implant circumstances was constructed. The in vivo strain data was converted to torque units (N.cm) to involve in loading definition of FE analysis. Upon processing of the FE analysis, the shear stress of peri-implant bone was evaluated to assume torsional shear stress strength of the bone-implant interface. Results The in vivo torque failure test yielded 5952 μstrains at custom-made manual torque wrench level and conversion of the strain data resulted in 750 N.cm. FE revealed that highest shear stress value in the trabecular bone, 121 MPa, was located at the first intimate contact with implant. Trabecular bone in contact with external surface of hollow implant body participated shear stress distribution, but not the bone resting inside of the hollow. Conclusion The torsional strength of hollow-screw implants is basically provided by the marginal bone and the hollow part has negligible effect on interfacial shear strength. PMID:17083739

  8. Standard magnitude prize reinforcers can be as efficacious as larger magnitude reinforcers in cocaine-dependent methadone patients

    PubMed Central

    Petry, Nancy M.; Alessi, Sheila M.; Barry, Danielle; Carroll, Kathleen M.

    2014-01-01

    Objective Contingency management (CM) reduces cocaine use in methadone patients, but only about 50% of patients respond to CM interventions. This study evaluated whether increasing magnitudes of reinforcement will improve outcomes. Methods Cocaine-dependent methadone patients (N = 240) were randomized to one of four 12-week treatment conditions: usual care (UC), UC plus “standard” prize CM in which average expected prize earnings were about $300, UC plus high magnitude prize CM in which average expected prize earnings were about $900, or UC plus voucher CM with an expected maximum of about $900 in vouchers. Results All three CM conditions yielded significant reductions in cocaine use relative to UC, with effect sizes (d) ranging from 0.38 to 0.59. No differences were noted between CM conditions, with at least 55% of patients in each CM condition achieving one week or more of cocaine abstinence versus 35% in UC. During the 12 weeks after the intervention ended, CM increased time until relapse relative to UC, but the effects of CM were no longer significant at a 12-month follow-up. Conclusions Providing the standard magnitude of $300 in prizes was as effective as larger magnitude CM in cocaine-dependent methadone patients in this study. Given its strong evidence base and relatively low costs, standard magnitude prize CM should be considered for adoption in methadone clinics to encourage cocaine abstinence, but new methods need to be developed to sustain abstinence. PMID:25198284

  9. Sequential provisional implant prosthodontics therapy.

    PubMed

    Zinner, Ira D; Markovits, Stanley; Jansen, Curtis E; Reid, Patrick E; Schnader, Yale E; Shapiro, Herbert J

    2012-01-01

    The fabrication and long-term use of first- and second-stage provisional implant prostheses is critical to create a favorable prognosis for function and esthetics of a fixed-implant supported prosthesis. The fixed metal and acrylic resin cemented first-stage prosthesis, as reviewed in Part I, is needed for prevention of adjacent and opposing tooth movement, pressure on the implant site as well as protection to avoid micromovement of the freshly placed implant body. The second-stage prosthesis, reviewed in Part II, should be used following implant uncovering and abutment installation. The patient wears this provisional prosthesis until maturation of the bone and healing of soft tissues. The second-stage provisional prosthesis is also a fail-safe mechanism for possible early implant failures and also can be used with late failures and/or for the necessity to repair the definitive prosthesis. In addition, the screw-retained provisional prosthesis is used if and when an implant requires removal or other implants are to be placed as in a sequential approach. The creation and use of both first- and second-stage provisional prostheses involve a restorative dentist, dental technician, surgeon, and patient to work as a team. If the dentist alone cannot do diagnosis and treatment planning, surgery, and laboratory techniques, he or she needs help by employing the expertise of a surgeon and a laboratory technician. This team approach is essential for optimum results. PMID:23220306

  10. [Allergy diagnostics in implant intolerance].

    PubMed

    Thomas, P; Thomsen, M

    2008-02-01

    To clarify a suspected implant allergy, a patch test with implant metals and bone cement components can be used. The (immuno)histology of periimplant tissue may also indicate T-lymphocyte-dominant inflammation. Identification of histological allergy characteristics and evaluation of the lymphocyte transformation test beyond indications of sensitization will be possible only when larger studies are available. PMID:18227997

  11. Implant Maintenance: A Clinical Update

    PubMed Central

    Gulati, Minkle; Govila, Vivek; Anand, Vishal; Anand, Bhargavi

    2014-01-01

    Introduction. The differences in the supporting structure of the implant make them more susceptible to inflammation and bone loss when plaque accumulates as compared to the teeth. Therefore, a comprehensive maintenance protocol should be followed to ensure the longevity of the implant. Material and Method. A research to provide scientific evidence supporting the feasibility of various implant care methods was carried out using various online resources to retrieve relevant studies published since 1985. Results. The electronic search yielded 708 titles, out of which a total of 42 articles were considered appropriate and finally included for the preparation of this review article. Discussion. A typical maintenance visit for patients with dental implants should last 1 hour and should be scheduled every 3 months to evaluate any changes in their oral and general history. It is essential to have a proper instrument selection to prevent damage to the implant surface and trauma to the peri-implant tissues. Conclusion. As the number of patients opting for dental implants is increasing, it becomes increasingly essential to know the differences between natural teeth and implant care and accept the challenges of maintaining these restorations. PMID:27437506

  12. Porous metal for orthopedics implants

    PubMed Central

    Matassi, Fabrizio; Botti, Alessandra; Sirleo, Luigi; Carulli, Christian; Innocenti, Massimo

    2013-01-01

    Summary Porous metal has been introduced to obtain biological fixation and improve longevity of orthopedic implants. The new generation of porous metal has intriguing characteristics that allows bone healing and high osteointegration of the metallic implants. This article gives an overview about biomaterials properties of the contemporary class of highly porous metals and about the clinical use in orthopaedic surgery. PMID:24133527

  13. Regenerative Surgical Treatment of Peri-implantitis

    ClinicalTrials.gov

    2016-08-31

    Failure of Dental Implant Due to Infection; Infection; Inflammation; Peri-implantitis; Bacterial Infections; Bleeding of Subgingival Space; Molecular Sequence Variation; Periodontal Diseases; Mouth Diseases

  14. Use of grommets for flexible implant resection arthroplasty of the metacarpophalangeal joint.

    PubMed

    Swanson, A B; de Groot Swanson, G; Ishikawa, H

    1997-09-01

    In 1987, after 11 years of research, press fit titanium circumferential grommets were introduced for arthroplasty of the metacarpophalangeal joint to protect the flexible hinge implant midsection from sharp bony edges and shearing forces that can initiate implant abrasions and tears leading to implant fracture and formation of silicone wear particles. The effectiveness of the titanium circumferential grommets was assessed by comparing the results of 170 metacarpophalangeal joint implant (high performance) arthroplasties performed with (139 joints) and without (31 joints) grommets in 38 patients presenting an average 5.8 years followup. Both groups obtained pain relief, functional motion, stability, and correction of deformity. There was no evidence of particulate synovitis or infection. There were four implant fractures (12.9%) in the nongrommet group, and one (0.7%), because of implant rotation, in the grommet group. Although favorable bone remodeling was observed in both groups, the grommet group showed greater bone preservation at the metaphyseal and midshaft levels and increased intramedullary bone production around the implant stems. The results depend on appropriate surgical staging, meticulous operative and postoperative techniques, severity and progression of disease, and implant durability. The circumferential grommets safely and effectively protect the implant to bone interface to further the durability of implant arthroplasty of the metacarpophalangeal joint. PMID:9308520

  15. Implanted Miniaturized Antenna for Brain Computer Interface Applications: Analysis and Design

    PubMed Central

    Zhao, Yujuan; Rennaker, Robert L.; Hutchens, Chris; Ibrahim, Tamer S.

    2014-01-01

    Implantable Brain Computer Interfaces (BCIs) are designed to provide real-time control signals for prosthetic devices, study brain function, and/or restore sensory information lost as a result of injury or disease. Using Radio Frequency (RF) to wirelessly power a BCI could widely extend the number of applications and increase chronic in-vivo viability. However, due to the limited size and the electromagnetic loss of human brain tissues, implanted miniaturized antennas suffer low radiation efficiency. This work presents simulations, analysis and designs of implanted antennas for a wireless implantable RF-powered brain computer interface application. The results show that thin (on the order of 100 micrometers thickness) biocompatible insulating layers can significantly impact the antenna performance. The proper selection of the dielectric properties of the biocompatible insulating layers and the implantation position inside human brain tissues can facilitate efficient RF power reception by the implanted antenna. While the results show that the effects of the human head shape on implanted antenna performance is somewhat negligible, the constitutive properties of the brain tissues surrounding the implanted antenna can significantly impact the electrical characteristics (input impedance, and operational frequency) of the implanted antenna. Three miniaturized antenna designs are simulated and demonstrate that maximum RF power of up to 1.8 milli-Watts can be received at 2 GHz when the antenna implanted around the dura, without violating the Specific Absorption Rate (SAR) limits. PMID:25079941

  16. A planning system for transapical aortic valve implantation

    NASA Astrophysics Data System (ADS)

    Gessat, Michael; Merk, Denis R.; Falk, Volkmar; Walther, Thomas; Jacobs, Stefan; Nöttling, Alois; Burgert, Oliver

    2009-02-01

    Stenosis of the aortic valve is a common cardiac disease. It is usually corrected surgically by replacing the valve with a mechanical or biological prosthesis. Transapical aortic valve implantation is an experimental minimally invasive surgical technique that is applied to patients with high operative risk to avoid pulmonary arrest. A stented biological prosthesis is mounted on a catheter. Through small incisions in the fifth intercostal space and the apex of the heart, the catheter is positioned under flouroscopy in the aortic root. The stent is expanded and unfolds the valve which is thereby implanted into the aortic root. Exact targeting is crucial, since major complications can arise from a misplaced valve. Planning software for the perioperative use is presented that allows for selection of the best fitting implant and calculation of the safe target area for that implant. The software uses contrast enhanced perioperative DynaCT images acquired under rapid pacing. In a semiautomatic process, a surface segmentation of the aortic root is created. User selected anatomical landmarks are used to calculate the geometric constraints for the size and position of the implant. The software is integrated into a PACS network based on DICOM communication to query and receive the images and implants templates from a PACS server. The planning results can be exported to the same server and from there can be rertieved by an intraoperative catheter guidance device.

  17. [PIP breast implants: a series of 217 explants].

    PubMed

    Tropet, Yves; Oulharj, Sarah; Pauchot, Julien

    2013-01-01

    On 29 march 2010, the French authorities (Afssaps) issued a health alert concerning breast implants manufactured by the company Poly Implant Prothèse, because of a high rupture rate. Marketing authorization was suspended and the use of PIP breast implants was prohibited. In our hospital department, 630 patients had received these prostheses since 2001. We conducted a retrospective study of all patients who underwent explantation between May 2010 and January 2012, corresponding to 434 explanted prostheses and 217 patients, all operated on by the same surgeon. Median age was 42 years and the prostheses had been implanted an average of 4 years 7 months earlier. We found that 38 implants (8.7%) had ruptured, in 33 patients (15.2%). Five patients had bilateral rupture. Preoperative ultrasonography, performed in 166 patients, detected 30 ruptures that were confirmed at surgery, but missed a further 9 cases (8%). Biopsy samples of capsular tissue were obtained in 103 cases, revealing granulation tissue possibly due to silicone exposure in 33 cases, 22 of which were associated with intact implants. Surgical complications included three hematomas, with no infections. Despite the low false-negative rate of ultrasonography, we recommend systematic preventive explantation, owing to the risk of silicone impregnation of capsular tissue even in the absence of rupture. PMID:24672984

  18. A remotely powered implantable biomedical system with location detector.

    PubMed

    Kilinc, Enver G; Ghanad, Mehrdad A; Maloberti, Franco; Dehollain, Catherine

    2015-02-01

    An universal remote powering and communication system is presented for the implantable medical devices. The system be interfaced with different sensors or actuators. A mobile external unit controls the operation of the implantable chip and reads the sensor's data. A locator system is proposed to align the mobile unit with the implant unit for the efficient magnetic power transfer. The location of the implant is detected with 6 mm resolution from the rectified voltage level at the implanted side. The rectified voltage level is fedback to the mobile unit to adjust the magnetic field strength and maximize the efficiency of the remote powering system. The sensor's data are transmitted by using a free running oscillator modulated with on-off key scheme. To tolerate large data carrier drifts, a custom designed receiver is implemented for the mobile unit. The circuits have been fabricated in 0.18 um CMOS technology. The remote powering link is optimized to deliver power at 13.56 MHz. On chip voltage regulator creates 1.8 V from a 0.9 V reference voltage to supply the sensor/actuator blocks. The implantable chip dissipates 595 μW and requires 1.48 V for start up. PMID:24988596

  19. Pacemakers and implantable cardioverter defibrillators--general and anesthetic considerations.

    PubMed

    Rapsang, Amy G; Bhattacharyya, Prithwis

    2014-01-01

    A pacemaking system consists of an impulse generator and lead or leads to carry the electrical impulse to the patient's heart. Pacemaker and implantable cardioverter defibrillator codes were made to describe the type of pacemaker or implantable cardioverter defibrillator implanted. Indications for pacing and implantable cardioverter defibrillator implantation were given by the American College of Cardiologists. Certain pacemakers have magnet-operated reed switches incorporated; however, magnet application can have serious adverse effects; hence, devices should be considered programmable unless known otherwise. When a device patient undergoes any procedure (with or without anesthesia), special precautions have to be observed including a focused history/physical examination, interrogation of pacemaker before and after the procedure, emergency drugs/temporary pacing and defibrillation, reprogramming of pacemaker and disabling certain pacemaker functions if required, monitoring of electrolyte and metabolic disturbance and avoiding certain drugs and equipments that can interfere with pacemaker function. If unanticipated device interactions are found, consider discontinuation of the procedure until the source of interference can be eliminated or managed and all corrective measures should be taken to ensure proper pacemaker function should be done. Post procedure, the cardiac rate and rhythm should be monitored continuously and emergency drugs and equipments should be kept ready and consultation with a cardiologist or a pacemaker-implantable cardioverter defibrillator service may be necessary. PMID:24907883

  20. Method for Providing Semiconductors Having Self-Aligned Ion Implant

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G. (Inventor)

    2014-01-01

    A method is disclosed that provides a self-aligned nitrogen-implant particularly suited for a Junction Field Effect Transistor (JFET) semiconductor device preferably comprised of a silicon carbide (SiC). This self-aligned nitrogen-implant allows for the realization of durable and stable electrical functionality of high temperature transistors such as JFETs. The method implements the self-aligned nitrogen-implant having predetermined dimensions, at a particular step in the fabrication process, so that the SiC junction field effect transistors are capable of being electrically operating continuously at 500.degree. C. for over 10,000 hours in an air ambient with less than a 10% change in operational transistor parameters.

  1. Method for Providing Semiconductors Having Self-Aligned Ion Implant

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G. (Inventor)

    2011-01-01

    A method is disclosed that provides a self-aligned nitrogen-implant particularly suited for a Junction Field Effect Transistor (JFET) semiconductor device preferably comprised of a silicon carbide (SiC). This self-aligned nitrogen-implant allows for the realization of durable and stable electrical functionality of high temperature transistors such as JFETs. The method implements the self-aligned nitrogen-implant having predetermined dimensions, at a particular step in the fabrication process, so that the SiC junction field effect transistors are capable of being electrically operating continuously at 500.degree. C. for over 10,000 hours in an air ambient with less than a 10% change in operational transistor parameters.

  2. [Experimental study of dental implants with nanostructured non-resorbable coating integration into bone tissue].

    PubMed

    Grigor'ian, A S; Khamraev, T K; Toporkova, A K; Amirov, A R

    2010-01-01

    In 2 dogs on both sides of mandible premolars were removed. In 3 months after dental alveolus healing intraosseous screwdriver dental implants (Konmet, Russia) were installed in the place of the removed teeth. Analogous operation was done on the contralateral side: the same type of implants were installed but with new nanostructured multifunctional biocompatible non-resorbable coating (MBNC) of the Ti-Ca-P-C-O-N composition. The animals were taken out of the experiment in 4 months after implants installation and implant-bone blocks were studied by SEM-method. According to the SEM-data in the region of the contact of implant-bone without new MBNC only fibrous connective tissue was formed. In case when MBNC was used the close welding of bone tissue with implant surface was observed that was considered as sign of osteointegration. PMID:21186642

  3. The Primary Implantation of Human Tumours to the Hamster Cheek Pouch

    PubMed Central

    Williams, Dorothy E.; Evans, D. M. D.; Blamey, R. W.

    1971-01-01

    The hamster cheek pouch is an immunologically privileged site. The present study is of simple implantation of human tumours direct from operative specimen to cheek pouch, in particular to determine whether tumour type influences the rate of successful implant. All implants were studied 10 or 20 days later. The use of cortisone significantly improved the number of implants growing. Carcinomas of the cervix were found to show growth in 55% of implants, in animals conditioned with cortisone. Growth from tumours of the uterine body, or from colorectal carcinomas, occurred in 25-30% of implants. Breast cancer gave poor results. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5 PMID:5144526

  4. Anatomic consideration for preventive implantation.

    PubMed

    Denissen, H W; Kalk, W; Veldhuis, H A; van Waas, M A

    1993-01-01

    The aim of preventive implant therapy is to prevent or delay loss of alveolar ridge bone mass. For use in an anatomic study of 60 mandibles, resorption of the alveolar ridge was classified into four preventive stages: (1) after extraction of teeth; (2) after initial resorption; (3) when the ridge has atrophied to a knife-edge shape; and (4) when only basal bone remains. Implantation in stage 3 necessitates removal of the knife-edge ridge to create space for cylindrical implants. Therefore, implantation in stage 2 is advocated to prevent the development of stage 3. The aim of implantation in stage 4 is to prevent total loss of function of the atrophic mandible. PMID:8359876

  5. Effects of an implant on temperature distribution in tissue during ultrasound diathermy.

    PubMed

    Sun, Ming-Kuan; Shieh, Jay; Chen, Chuin-Shan; Chiang, Hongsen; Huang, Chang-Wei; Chen, Wen-Shiang

    2016-09-01

    The effects of an implant on temperature distribution in a tissue-mimicking hydrogel phantom during the application of therapeutic ultrasound were investigated. In vitro experiments were conducted to compare the influences of plastic and metal implants on ultrasound diathermy and to calibrate parameters in finite element simulation models. The temperature histories and characteristics of the opaque (denatured) areas in the hydrogel phantoms predicted by the numerical simulations show good correlation with those observed in the in vitro experiments. This study provides an insight into the temperature profile in the vicinity of an implant by therapeutic ultrasound heating typically used for physiotherapy. A parametric study was conducted through numerical simulations to investigate the effects of several factors, such as implant material type, ultrasound operation frequency, implant thickness and tissue thickness on the temperature distribution in the hydrogel phantom. The results indicate that the implant material type and implant thickness are the main parameters influencing the temperature distribution. In addition, once the implant material and ultrasound operation frequency are chosen, an optimal implant thickness can be obtained so as to avoid overheating injuries in tissue. PMID:27150744

  6. The manufacture of generic replicas of implants for arthroplasty of the hip and knee: is it regulated and will it save money?

    PubMed

    Atrey, A; Heylen, S; Gosling, O; Porteous, M J L; Haddad, F S

    2016-07-01

    Joint replacement of the hip and knee remain very satisfactory operations. They are, however, expensive. The actual manufacturing of the implant represents only 30% of the final cost, while sales and marketing represent 40%. Recently, the patents on many well established and successful implants have expired. Companies have started producing and distributing implants that purport to replicate existing implants with good long-term results. The aims of this paper are to assess the legality, the monitoring and cost saving implications of such generic implants. We also assess how this might affect the traditional orthopaedic implant companies. Cite this article: Bone Joint J 2016;98-B:892-900. PMID:27365466

  7. Power Approaches for Implantable Medical Devices

    PubMed Central

    Ben Amar, Achraf; Kouki, Ammar B.; Cao, Hung

    2015-01-01

    Implantable medical devices have been implemented to provide treatment and to assess in vivo physiological information in humans as well as animal models for medical diagnosis and prognosis, therapeutic applications and biological science studies. The advances of micro/nanotechnology dovetailed with novel biomaterials have further enhanced biocompatibility, sensitivity, longevity and reliability in newly-emerged low-cost and compact devices. Close-loop systems with both sensing and treatment functions have also been developed to provide point-of-care and personalized medicine. Nevertheless, one of the remaining challenges is whether power can be supplied sufficiently and continuously for the operation of the entire system. This issue is becoming more and more critical to the increasing need of power for wireless communication in implanted devices towards the future healthcare infrastructure, namely mobile health (m-Health). In this review paper, methodologies to transfer and harvest energy in implantable medical devices are introduced and discussed to highlight the uses and significances of various potential power sources. PMID:26580626

  8. Power Approaches for Implantable Medical Devices.

    PubMed

    Ben Amar, Achraf; Kouki, Ammar B; Cao, Hung

    2015-01-01

    Implantable medical devices have been implemented to provide treatment and to assess in vivo physiological information in humans as well as animal models for medical diagnosis and prognosis, therapeutic applications and biological science studies. The advances of micro/nanotechnology dovetailed with novel biomaterials have further enhanced biocompatibility, sensitivity, longevity and reliability in newly-emerged low-cost and compact devices. Close-loop systems with both sensing and treatment functions have also been developed to provide point-of-care and personalized medicine. Nevertheless, one of the remaining challenges is whether power can be supplied sufficiently and continuously for the operation of the entire system. This issue is becoming more and more critical to the increasing need of power for wireless communication in implanted devices towards the future healthcare infrastructure, namely mobile health (m-Health). In this review paper, methodologies to transfer and harvest energy in implantable medical devices are introduced and discussed to highlight the uses and significances of various potential power sources. PMID:26580626

  9. [Orthopaedic implants. Application outside of patient care?].

    PubMed

    Manhart, J; Dietze, A; Büttner, A

    2015-01-01

    Internal fracture fixation represents a widespread concept for the treatment of fractures. As the number of implants increases, person tracking may be possible. In spring 2010 near Rostock (Germany), human remains including a stainless steel nail were found. Forensic analysis considered the parts of skeleton to belong to a man of medium height, exposed to outdoor conditions for several years to a few decades. The tibial nail was analysed and according to the product identification number possible hospitals of implant placement and transportation paths were determined and screened. Furthermore a match analysis of the database of missing individuals of the last 15 years was undertaken and a DNA match analysis identified a local individual who had been missing since winter 2003. Equipped with the actual patient's identity, out of academic interest a survey of clinical documents such as discharge letters and operative reports was performed, but was inconclusive. Although technically feasible, tracking the patient in this case based on the implant product number itself was unsuccessful. In this case report, the feasibility, validity and efficiency of this option are presented and discussed. PMID:24458026

  10. An Implanted, Stimulated Muscle Powered Piezoelectric Generator

    NASA Technical Reports Server (NTRS)

    Lewandowski, Beth; Gustafson, Kenneth; Kilgore, Kevin

    2007-01-01

    A totally implantable piezoelectric generator system able to harness power from electrically activated muscle could be used to augment the power systems of implanted medical devices, such as neural prostheses, by reducing the number of battery replacement surgeries or by allowing periods of untethered functionality. The features of our generator design are no moving parts and the use of a portion of the generated power for system operation and regulation. A software model of the system has been developed and simulations have been performed to predict the output power as the system parameters were varied within their constraints. Mechanical forces that mimic muscle forces have been experimentally applied to a piezoelectric generator to verify the accuracy of the simulations and to explore losses due to mechanical coupling. Depending on the selection of system parameters, software simulations predict that this generator concept can generate up to approximately 700 W of power, which is greater than the power necessary to drive the generator, conservatively estimated to be 50 W. These results suggest that this concept has the potential to be an implantable, self-replenishing power source and further investigation is underway.

  11. The Magnitude of Premenstrual and Menstrual Mood Changes in Adolescents.

    ERIC Educational Resources Information Center

    Golub, Sharon; Murphy, Denise

    Frequent mood changes in adolescents are often attributed to the influence of shifting hormone levels. The presence and magnitude of menstrual-related mood changes in adolescent women were examined in 10th and 11th grade females (N=158) who completed the Menstrual Distress Questionnaire (MDQ). Self-reports of the onset date for the next two…

  12. Strategy Use and Strategy Choice in Fraction Magnitude Comparison

    ERIC Educational Resources Information Center

    Fazio, Lisa K.; DeWolf, Melissa; Siegler, Robert S.

    2016-01-01

    We examined, on a trial-by-trial basis, fraction magnitude comparison strategies of adults with more and less mathematical knowledge. College students with high mathematical proficiency used a large variety of strategies that were well tailored to the characteristics of the problems and that were guaranteed to yield correct performance if executed…

  13. Asteroid magnitudes, UBV colors, and IRAS albedos and diameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1989-01-01

    This paper lists absolute magnitudes and slope parameters for known asteroids numbered through 3318. The values presented are those used in reducing asteroid IR flux data obtained with the IRAS. U-B colors are given for 938 asteroids, and B-V colors are given for 945 asteroids. The IRAS albedos and diameters are tabulated for 1790 asteroids.

  14. Error magnitude estimation in model-reference adaptive systems

    NASA Technical Reports Server (NTRS)

    Colburn, B. K.; Boland, J. S., III

    1975-01-01

    A second order approximation is derived from a linearized error characteristic equation for Lyapunov designed model-reference adaptive systems and is used to estimate the maximum error between the model and plant states, and the time to reach this peak following a plant perturbation. The results are applicable in the analysis of plants containing magnitude-dependent nonlinearities.

  15. Fraction Development in Children: Importance of Building Numerical Magnitude Understanding

    ERIC Educational Resources Information Center

    Jordan, Nancy C.; Carrique, Jessica; Hansen, Nicole; Resnick, Ilyse

    2016-01-01

    This chapter situates fraction learning within the integrated theory of numerical development. We argue that the understanding of numerical magnitudes for whole numbers as well as for fractions is critical to fraction learning in particular and mathematics achievement more generally. Results from the Delaware Longitudinal Study, which examined…

  16. Magnitude Estimation with Noisy Integrators Linked by an Adaptive Reference

    PubMed Central

    Thurley, Kay

    2016-01-01

    Judgments of physical stimuli show characteristic biases; relatively small stimuli are overestimated whereas relatively large stimuli are underestimated (regression effect). Such biases likely result from a strategy that seeks to minimize errors given noisy estimates about stimuli that itself are drawn from a distribution, i.e., the statistics of the environment. While being conceptually well described, it is unclear how such a strategy could be implemented neurally. The present paper aims toward answering this question. A theoretical approach is introduced that describes magnitude estimation as two successive stages of noisy (neural) integration. Both stages are linked by a reference memory that is updated with every new stimulus. The model reproduces the behavioral characteristics of magnitude estimation and makes several experimentally testable predictions. Moreover, the model identifies the regression effect as a means of minimizing estimation errors and explains how this optimality strategy depends on the subject's discrimination abilities and on the stimulus statistics. The latter influence predicts another property of magnitude estimation, the so-called range effect. Beyond being successful in describing decision-making, the present work suggests that noisy integration may also be important in processing magnitudes. PMID:26909028

  17. The effect of crosstalk on depth magnitude in thin structures

    NASA Astrophysics Data System (ADS)

    Tsirlin, Inna; Wilcox, Laurie M.; Allison, Robert S.

    2011-03-01

    Stereoscopic displays must present separate images to the viewer's left and right eyes. Crosstalk is the unwanted contamination of one eye's image from the image of the other eye. It has been shown to cause distortions, reduce image quality and visual comfort and increase perceived workload when performing visual tasks. Crosstalk also affects one's ability to perceive stereoscopic depth although little consideration has been given to the perception of depth magnitude in the presence of crosstalk. In this paper we extend a previous study (Tsirlin, Allison & Wilcox, 2010, submitted) on the perception of depth magnitude in stereoscopic occluding and non-occluding surfaces to the special case of crosstalk in thin structures. Crosstalk in thin structures differs qualitatively from that in larger objects due to the separation of the ghost and real images and thus theoretically could have distinct perceptual consequences. To address this question we used a psychophysical paradigm, where observers estimated the perceived depth difference between two thin vertical bars using a measurement scale. Our data show that crosstalk degrades perceived depth. As crosstalk levels increased the magnitude of perceived depth decreased, especially for stimuli with larger relative disparities. In contrast to the effect of crosstalk on depth magnitude in larger objects, in thin structures, a significant detrimental effect was found at all disparities. Our findings, when considered with the other perceptual consequences of crosstalk, suggest that its presence in S3D media even in modest amounts will reduce observers' satisfaction.

  18. High magnitude head impacts experienced during youth football practices.

    PubMed

    Young, Tyler; Rowson, Steven; Duma, Stefan M

    2014-01-01

    To reduce the risk of concussion in the 3.5 million youth athletes who participate in organized football leagues in the United States each year, practice structure can be modified to decrease impact frequency and magnitude. The objective of this study is to identify activities that result in high magnitude head impacts in youth football players during practice. The HIT System was used to record the head acceleration magnitude, impact location on the helmet, and time of each impact for each game and practice players participated in. These data were used to quantify the head impact exposure associated with players between the ages of 9 and 11 years. Video footage recorded during each practice and game session was used to identify the activity associated with any impact above 45 g. The incidence rate of high magnitude impacts in various activities were compared by normalizing by the amount of time associated with each activity. It was determined that scrimmages accounted for 0.094 impacts greater than 45 g per minute in practices while contact drills contributed to 0.102 impacts greater than 45 g per minute during practices. The results of this study indicate future youth football practice modifications should focus on both scrimmages and contact drills. PMID:25405410

  19. Crystal measures short-term, large-magnitude forces

    NASA Technical Reports Server (NTRS)

    Pfeiffer, C. G.

    1965-01-01

    By using the magnitude of piezoelectric crystal response to distortion and compression, this device measures transient accelerations and their rate of change. The invention could be used in a servo control system by supplementing the accelerometer and taking over its function when its range was exceeded.

  20. The Role of Executive Functions in Numerical Magnitude Skills

    ERIC Educational Resources Information Center

    Kolkman, Meijke E.; Hoijtink, Herbert J. A.; Kroesbergen, Evelyn H.; Leseman, Paul P. M.

    2013-01-01

    Executive functions (EF) are closely related to math performance. Little is known, however, about the role of EF in numerical magnitude skills (NS), although these skills are widely acknowledged to be important precursors of math learning. The current study focuses on the different roles of updating, shifting, and inhibition in NS. EF and NS were…

  1. What Is the Meaning of the Physical Magnitude "Work"?

    ERIC Educational Resources Information Center

    Kanderakis, Nikos

    2014-01-01

    Usually, in physics textbooks, the physical magnitude "work" is introduced as the product of a force multiplied by its displacement, in relation to the transfer of energy. In other words, "work" is presented as an internal affair of physics theory, while its relation to the world of experience, that is its empirical meaning, is…

  2. Discriminability and Sensitivity to Reinforcer Magnitude in a Detection Task

    ERIC Educational Resources Information Center

    Alsop, Brent; Porritt, Melissa

    2006-01-01

    Three pigeons discriminated between two sample stimuli (intensities of red light). The difficulty of the discrimination was varied over four levels. At each level, the relative reinforcer magnitude for the two correct responses was varied across conditions, and the reinforcer rates were equal. Within levels, discriminability between the sample…

  3. Neural processing of reward magnitude under varying attentional demands.

    PubMed

    Stoppel, Christian Michael; Boehler, Carsten Nicolas; Strumpf, Hendrik; Heinze, Hans-Jochen; Hopf, Jens-Max; Schoenfeld, Mircea Ariel

    2011-04-01

    Central to the organization of behavior is the ability to represent the magnitude of a prospective reward and the costs related to obtaining it. Therein, reward-related neural activations are discounted in dependence of the effort required to resolve a given task. Varying attentional demands of the task might however affect reward-related neural activations. Here we employed fMRI to investigate the neural representation of expected values during a monetary incentive delay task with varying attentional demands. Following a cue, indicating at the same time the difficulty (hard/easy) and the reward magnitude (high/low) of the upcoming trial, subjects performed an attention task and subsequently received feedback about their monetary reward. Consistent with previous results, activity in anterior-cingulate, insular/orbitofrontal and mesolimbic regions co-varied with the anticipated reward-magnitude, but also with the attentional requirements of the task. These activations occurred contingent on action-execution and resembled the response time pattern of the subjects. In contrast, cue-related activations, signaling the forthcoming task-requirements, were only observed within attentional control structures. These results suggest that anticipated reward-magnitude and task-related attentional demands are concurrently processed in partially overlapping neural networks of anterior-cingulate, insular/orbitofrontal, and mesolimbic regions. PMID:21295019

  4. Children's Sensitivity to Error Magnitude when Evaluating Informants

    ERIC Educational Resources Information Center

    Einav, Shiri; Robinson, Elizabeth J.

    2010-01-01

    Three experiments examined children's (N = 80; 40; 48) sensitivity to error magnitude as a measure of informants' past accuracy, and indication of future reliability. Experiments 1 and 2 assessed whether, in a forced-choice task, children would evaluate as better and show greater trust in an informant whose previous errors were consistently within…

  5. Magnitude Estimation with Noisy Integrators Linked by an Adaptive Reference.

    PubMed

    Thurley, Kay

    2016-01-01

    Judgments of physical stimuli show characteristic biases; relatively small stimuli are overestimated whereas relatively large stimuli are underestimated (regression effect). Such biases likely result from a strategy that seeks to minimize errors given noisy estimates about stimuli that itself are drawn from a distribution, i.e., the statistics of the environment. While being conceptually well described, it is unclear how such a strategy could be implemented neurally. The present paper aims toward answering this question. A theoretical approach is introduced that describes magnitude estimation as two successive stages of noisy (neural) integration. Both stages are linked by a reference memory that is updated with every new stimulus. The model reproduces the behavioral characteristics of magnitude estimation and makes several experimentally testable predictions. Moreover, the model identifies the regression effect as a means of minimizing estimation errors and explains how this optimality strategy depends on the subject's discrimination abilities and on the stimulus statistics. The latter influence predicts another property of magnitude estimation, the so-called range effect. Beyond being successful in describing decision-making, the present work suggests that noisy integration may also be important in processing magnitudes. PMID:26909028

  6. Effect of Surgical Technique on Corneal Implant Performance

    PubMed Central

    Ljunggren, Monika Kozak; Elizondo, Rodolfo A.; Edin, Joel; Olsen, David; Merrett, Kimberley; Lee, Chyan-Jang; Salerud, Göran; Polarek, James; Fagerholm, Per; Griffith, May

    2014-01-01

    Purpose Our aim was to determine the effect of a surgical technique on biomaterial implant performance, specifically graft retention. Methods Twelve mini pigs were implanted with cell-free, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS) cross-linked recombinant human collagen type III (RHCIII) hydrogels as substitutes for donor corneal allografts using overlying sutures with or without human amniotic membrane (HAM) versus interrupted sutures with HAM. The effects of the retention method were compared as well as the effects of collagen concentration (13.7% to 15% RHCIII). Results All implanted corneas showed initial haze that cleared with time, resulting in corneas with optical clarity matching those of untreated controls. Biochemical analysis showed that by 12 months post operation, the initial RHCIII implants had been completely remodeled, as type I collagen, was the major collagenous protein detected, whereas no RHCIII could be detected. Histological analysis showed all implanted corneas exhibited regeneration of epithelial and stromal layers as well as nerves, along with touch sensitivity and tear production. Most neovascularization was seen in corneas stabilized by interrupted sutures. Conclusions This showed that the surgical technique used does have a significant effect on the overall performance of corneal implants, overlying sutures caused less vascularization than interrupted sutures. Translational Relevance Understanding the significance of the suturing technique can aid the selection of the most appropriate procedure when implanting artificial corneal substitutes. The same degree of regeneration, despite a higher collagen content indicates that future material development can progress toward stronger, more resistant implants. PMID:24749003

  7. Implications of Minimizing Trauma During Conventional Cochlear Implantation

    PubMed Central

    Carlson, Matthew L.; Driscoll, Colin L. W.; Gifford, René H.; Service, Geoffrey J.; Tombers, Nicole M.; Hughes-Borst, Becky J.; Neff, Brian A.; Beatty, Charles W.

    2014-01-01

    Objective To describe the relationship between implantation-associated trauma and postoperative speech perception scores among adult and pediatric patients undergoing cochlear implantation using conventional length electrodes and minimally traumatic surgical techniques. Study Design Retrospective chart review (2002–2010). Setting Tertiary academic referral center. Patients All subjects with significant preoperative low-frequency hearing (≤70 dB HL at 250 Hz) who underwent cochlear implantation with a newer generation implant electrode (Nucleus Contour Advance, Advanced Bionics HR90K [1J and Helix], and Med El Sonata standard H array) were reviewed. Intervention(s) Preimplant and postimplant audiometric thresholds and speech recognition scores were recorded using the electronic medical record. Main Outcome Measure(s) Postimplantation pure tone threshold shifts were used as a surrogate measure for extent of intracochlear injury and correlated with postoperative speech perception scores. Results Between 2002 and 2010, 703 cochlear implant (CI) operations were performed. Data from 126 implants were included in the analysis. The mean preoperative low-frequency pure-tone average was 55.4 dB HL. Hearing preservation was observed in 55% of patients. Patients with hearing preservation were found to have significantly higher postoperative speech perception performance in the cochlear implantation-only condition than those who lost all residual hearing. Conclusion Conservation of acoustic hearing after conventional length cochlear implantation is unpredictable but remains a realistic goal. The combination of improved technology and refined surgical technique may allow for conservation of some residual hearing in more than 50% of patients. Germane to the conventional length CI recipient with substantial hearing loss, minimizing trauma allows for improved speech perception in the electric condition. These findings support the use of minimally traumatic techniques in all CI

  8. Revision total hip and knee arthroplasty implant identification: implications for use of Unique Device Identification 2012 AAHKS member survey results.

    PubMed

    Wilson, Natalia A; Jehn, Megan; York, Sally; Davis, Charles M

    2014-02-01

    FDA's Unique Device Identification (UDI) Rule will mandate manufacturers to assign unique identifiers to their marketed devices. UDI use is expected to improve implant documentation and identification. A 2012 American Association of Hip and Knee Surgeons membership survey explored revision total hip and knee arthroplasty implant identification processes. 87% of surgeons reported regularly using at least 3 methods to identify failed implants pre-operatively. Median surgeon identification time was 20 min; median staff time was 30 min. 10% of implants could not be identified pre-operatively. 2% could not be identified intra-operatively. UDI in TJA registry and UDI in EMR were indicated practices to best support implant identification and save time. FDA's UDI rule sets the foundation for UDI use in patient care settings as standard practice for implant documentation. PMID:23890830

  9. Bayesian Predictive Distribution for the Magnitude of the Largest Aftershock

    NASA Astrophysics Data System (ADS)

    Shcherbakov, R.

    2014-12-01

    Aftershock sequences, which follow large earthquakes, last hundreds of days and are characterized by well defined frequency-magnitude and spatio-temporal distributions. The largest aftershocks in a sequence constitute significant hazard and can inflict additional damage to infrastructure. Therefore, the estimation of the magnitude of possible largest aftershocks in a sequence is of high importance. In this work, we propose a statistical model based on Bayesian analysis and extreme value statistics to describe the distribution of magnitudes of the largest aftershocks in a sequence. We derive an analytical expression for a Bayesian predictive distribution function for the magnitude of the largest expected aftershock and compute the corresponding confidence intervals. We assume that the occurrence of aftershocks can be modeled, to a good approximation, by a non-homogeneous Poisson process with a temporal event rate given by the modified Omori law. We also assume that the frequency-magnitude statistics of aftershocks can be approximated by Gutenberg-Richter scaling. We apply our analysis to 19 prominent aftershock sequences, which occurred in the last 30 years, in order to compute the Bayesian predictive distributions and the corresponding confidence intervals. In the analysis, we use the information of the early aftershocks in the sequences (in the first 1, 10, and 30 days after the main shock) to estimate retrospectively the confidence intervals for the magnitude of the expected largest aftershocks. We demonstrate by analysing 19 past sequences that in many cases we are able to constrain the magnitudes of the largest aftershocks. For example, this includes the analysis of the Darfield (Christchurch) aftershock sequence. The proposed analysis can be used for the earthquake hazard assessment and forecasting associated with the occurrence of large aftershocks. The improvement in instrumental data associated with early aftershocks can greatly enhance the analysis and

  10. The refractive outcome of Toric Lentis Mplus implant in cataract surgery

    PubMed Central

    Chiam, Patrick J; Quah, Say A

    2016-01-01

    AIM To evaluate the refractive outcome of Toric Lentis Mplus intraocular lens (IOL) implant. METHODS This is a retrospective case series. Consecutive patients with corneal astigmatism of at least 1.5 D had Toric Lentis Mplus IOL implant during cataract surgery. The exclusion criteria included irregular astigmatism on corneal topography, large scotopic pupil diameter (>6 mm), poor visual potential and significant ocular comorbidity. Postoperative manifest refraction, uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (BCVA), uncorrected intermediate visual acuity (UIVA) at 3/4 m and uncorrected near visual acuity (UNVA) were obtained. RESULTS There were 70 eyes from 49 patients in this study. Patients were refracted at a median of 8.9wk (range 4.0 to 15.5) from the operation date. Sixty-five percent of eyes had 6/7.5 (0.10 logMAR) or better, and 99% 6/12 (0.30 logMAR) or better postoperative UDVA. Eighty-nine percent could read Jaeger (J) 3 (0.28 logMAR) and 95% J5 (0.37 logMAR) at 40 cm. The median magnitude of astigmatism decreased from 1.91 D to 0.49 D (Wilcoxon, P<0.001) after the operation. The range of the cylindrical error was reduced from 1.5-3.95 D (keratometric) preoperatively to 0.00-1.46 D (subjective refraction transposed to corneal plane) postoperatively. CONCLUSION Toric Lentis Mplus IOL has good predictability in reducing preexisting corneal astigmatism. PMID:27275424

  11. Toward Reconciling Magnitude Discrepancies Estimated from Paleoearthquake Data: A New Approach for Predicting Earthquake Magnitudes from Fault Segment Lengths

    NASA Astrophysics Data System (ADS)

    Carpenter, N. S.; Payne, S. J.; Schafer, A. L.

    2011-12-01

    We recognize a discrepancy in magnitudes estimated for several Basin and Range faults in the Intermountain Seismic Belt, U.S.A. For example, magnitudes predicted for the Wasatch (Utah), Lost River (Idaho), and Lemhi (Idaho) faults from fault segment lengths, Lseg, where lengths are defined between geometrical, structural, and/or behavioral discontinuities assumed to persistently arrest rupture, are consistently less than magnitudes calculated from displacements, D, along these same segments. For self-similarity, empirical relationships (e.g. Wells and Coppersmith, 1994) should predict consistent magnitudes (M) using diverse fault dimension values for a given fault (i.e. M ~ Lseg, should equal M ~ D). Typically, the empirical relationships are derived from historical earthquake data and parameter values used as input into these relationships are determined from field investigations of paleoearthquakes. A commonly used assumption - grounded in the characteristic-earthquake model of Schwartz and Coppersmith (1984) - is equating Lseg with surface rupture length, SRL. Many large historical events yielded secondary and/or sympathetic faulting (e.g. 1983 Borah Peak, Idaho earthquake) which are included in the measurement of SRL and used to derive empirical relationships. Therefore, calculating magnitude from the M ~ SRL relationship using Lseg as SRL leads to an underestimation of magnitude and the M ~ Lseg and M ~ D discrepancy. Here, we propose an alternative approach to earthquake magnitude estimation involving a relationship between moment magnitude, Mw, and length, where length is Lseg instead of SRL. We analyze seven historical, surface-rupturing, strike-slip and normal faulting earthquakes for which segmentation of the causative fault and displacement data are available and whose rupture included at least one entire fault segment, but not two or more. The preliminary Mw ~ Lseg results are strikingly consistent with Mw ~ D calculations using paleoearthquake data for

  12. A Hip Implant Energy Harvester

    NASA Astrophysics Data System (ADS)

    Pancharoen, K.; Zhu, D.; Beeby, S. P.

    2014-11-01

    This paper presents a kinetic energy harvester designed to be embedded in a hip implant which aims to operate at a low frequency associated with body motion of patients. The prototype is designed based on the constrained volume available in a hip prosthesis and the challenge is to harvest energy from low frequency movements (< 1 Hz) which is an average frequency during free walking of a patient. The concept of magnetic-force-driven energy harvesting is applied to this prototype considering the hip movements during routine activities of patients. The magnetic field within the harvester was simulated using COMSOL. The simulated resonant frequency was around 30 Hz and the voltage induced in a coil was predicted to be 47.8 mV. A prototype of the energy harvester was fabricated and tested. A maximum open circuit voltage of 39.43 mV was obtained and the resonant frequency of 28 Hz was observed. Moreover, the power output of 0.96 μW was achieved with an optimum resistive load of 250Ω.

  13. Potential impact of prostate edema on the dosimetry of permanent seed implants using the new {sup 131}Cs (model CS-1) seeds

    SciTech Connect

    Chen Zhe; Deng Jun; Roberts, Kenneth; Nath, Ravinder

    2006-04-15

    Our aim in this work was to study the potential dosimetric effect of prostate edema on the accuracy of conventional pre- and post-implant dosimetry for prostate seed implants using the newly introduced {sup 131}Cs seed, whose radioactive decay half-life ({approx}9.7 days) is directly comparable to the average edema resolution half-life ({approx}10 days) observed previously by Waterman et al. for {sup 125}I implants [Int. J. Radiat. Oncol. Biol. Phys. 41, 1069-1077 (1998)]. A systematic calculation of the relative dosimetry effect of prostate edema on the {sup 131}Cs implant was performed by using an analytic solution obtained previously [Int. J. Radiat. Oncol. Biol. Phys. 47, 1405-1419 (2000)]. It was found that conventional preimplant dosimetry always overestimates the true delivered dose as it ignores the temporary increase of the interseed distance caused by edema. The overestimation for {sup 131}Cs implants ranged from 1.2% (for a small edema with a magnitude of 10% and a half-life of 2 days) to approximately 45% (for larger degree edema with a magnitude of 100% and a half-life of 25 days). The magnitude of pre- and post-implant dosimetry error for {sup 131}Cs implants was found to be similar to that of {sup 103}Pd implants for typical edema characteristics (magnitude <100%, and half-life <25 days); both of which are worse compared to {sup 125}I implants. The preimplant dosimetry error for {sup 131}Cs implants cannot be compensated effectively without knowing the edema characteristics before the seed implantation. On the other hand, the error resulted from a conventional post-implant dosimetry can be minimized (to within {+-}6%) for {sup 131}Cs implants if the post-implant dosimetry is performed at 10{+-}2 days post seed implantation. This 'optimum' post-implant dosimetry time is shorter than those determined previously for the {sup 103}Pd and {sup 125}I implants at 16{+-}4 days and 6{+-}1 weeks, respectively.

  14. Transcatheter aortic valve implantation.

    PubMed

    Nielsen, Hans Henrik Møller

    2012-12-01

    Transcatheter aortic valve implantation (TAVI) was introduced experimentally in 1989, based on a newly developed heart valve prosthesis - the stentvalve. The valve was invented by a Danish cardiologist named Henning Rud Andersen. The new valve was revolutionary. It was foldable and could be inserted via a catheter through an artery in the groin, without the need for heart lung machine. This allowed for a new valve implantation technique, much less invasive than conventional surgical aortic valve replacement (SAVR). Surgical aortic valve replacement is safe and improves symptoms along with survival. However, up to 1/3 of patients with aortic valve stenosis cannot complete the procedure due to frailty. The catheter technique was hoped to provide a new treatment option for these patients. The first human case was in 2002, but more widespread clinical use did not begin until 2006-2010. Today, in 2011, more than 40,000 valves have been implanted worldwide. Initially, because of the experimental character of the procedure, TAVI was reserved for patients who could not undergo SAVR due to high risk. The results in this group of patients were promising. The procedural safety was acceptable, and the patients experienced significant improvements in their symptoms. Three of the papers in this PhD-thesis are based on the outcome of TAVI at Skejby Hospital, in this high-risk population [I, II and IV]. Along with other international publications, they support TAVI as being superior to standard medical treatment, despite a high risk of prosthetic regurgitation. These results only apply to high-risk patients, who cannot undergo SAVR. The main purpose of this PhD study has been to investigate the quality of TAVI compared to SAVR, in order to define the indications for this new procedure. The article attached [V] describes a prospective clinical randomised controlled trial, between TAVI to SAVR in surgically amenable patients over 75 years of age with isolated aortic valve stenosis

  15. Turned versus anodised dental implants: a meta-analysis.

    PubMed

    Chrcanovic, B R; Albrektsson, T; Wennerberg, A

    2016-09-01

    The aim of this meta-analysis was to test the null hypothesis of no difference in the implant failure rates, marginal bone loss (MBL)and post-operative infection for patients being rehabilitated by turned versus anodised-surface implants, against the alternative hypothesis of a difference. An electronic search without time or language restrictions was undertaken in November 2015. Eligibility criteria included clinical human studies, either randomised or not. Thirty-eight publications were included. The results suggest a risk ratio of 2·82 (95% CI 1·95-4·06, P < 0·00001) for failure of turned implants, when compared to anodised-surface implants. Sensitivity analyses showed similar results when only the studies inserting implants in maxillae or mandibles were pooled. There were no statistically significant effects of turned implants on the MBL (mean difference-MD 0·02, 95%CI -0·16-0·20; P = 0·82) in comparison to anodised implants. The results of a meta-regression considering the follow-up period as a covariate suggested an increase of the MD with the increase in the follow-up time (MD increase 0·012 mm year(-1) ), however, without a statistical significance (P = 0·813). Due to lack of satisfactory information, meta-analysis for the outcome 'post-operative infection' was not performed. The results have to be interpreted with caution due to the presence of several confounding factors in the included studies. PMID:27295394

  16. Preferred tools and techniques for implantation of cardiac electronic devices in Europe: results of the European Heart Rhythm Association survey.

    PubMed

    Bongiorni, Maria Grazia; Proclemer, Alessandro; Dobreanu, Dan; Marinskis, Germanas; Pison, Laurent; Blomstrom-Lundqvist, Carina

    2013-11-01

    The aim of this European Heart Rhythm Association (EHRA) survey was to assess clinical practice in relation to the tools and techniques used for cardiac implantable electronic devices procedures in the European countries. Responses to the questionnaire were received from 62 members of the EHRA research network. The survey involved high-, medium-, and low-volume implanting centres, performing, respectively, more than 200, 100-199 and under 100 implants per year. The following topics were explored: the side approach for implantation, surgical techniques for pocket incision, first venous access for lead implantation, preference of lead fixation, preferred coil number for implantable cardioverter-defibrillator (ICD) leads, right ventricular pacing site, generator placement site, subcutaneous ICD implantation, specific tools and techniques for cardiac resynchronization therapy (CRT), lead implantation sequence in CRT, coronary sinus cannulation technique, target site for left ventricular lead placement, strategy in left ventricular lead implant failure, mean CRT implantation time, optimization of the atrioventricular (AV) and ventriculo-ventricular intervals, CRT implants in patients with permanent atrial fibrillation, AV node ablation in patients with permanent AF. This panoramic view allows us to find out the operator preferences regarding the techniques and tools for device implantation in Europe. The results showed different practices in all the fields we investigated, nevertheless the survey also outlines a good adherence to the common standards and recommendations. PMID:24170423

  17. A Retrospective Analysis of Ruptured Breast Implants

    PubMed Central

    Baek, Woo Yeol; Lew, Dae Hyun

    2014-01-01

    Background Rupture is an important complication of breast implants. Before cohesive gel silicone implants, rupture rates of both saline and silicone breast implants were over 10%. Through an analysis of ruptured implants, we can determine the various factors related to ruptured implants. Methods We performed a retrospective review of 72 implants that were removed for implant rupture between 2005 and 2014 at a single institution. The following data were collected: type of implants (saline or silicone), duration of implantation, type of implant shell, degree of capsular contracture, associated symptoms, cause of rupture, diagnostic tools, and management. Results Forty-five Saline implants and 27 silicone implants were used. Rupture was diagnosed at a mean of 5.6 and 12 years after insertion of saline and silicone implants, respectively. There was no association between shell type and risk of rupture. Spontaneous was the most common reason for the rupture. Rupture management was implant change (39 case), microfat graft (2 case), removal only (14 case), and follow-up loss (17 case). Conclusions Saline implants have a shorter average duration of rupture, but diagnosis is easier and safer, leading to fewer complications. Previous-generation silicone implants required frequent follow-up observation, and it is recommended that they be changed to a cohesive gel implant before hidden rupture occurs. PMID:25396188

  18. IMMEDIATE VERSUS DELAYED LOADING IMPLANTS: RATIONALE AND CONTROVERSIES.

    PubMed

    Corradini, G; Delle Donne, U; Boni, W; Tettamanti, L; Tagliabue, A

    2015-01-01

    Loading implants immediately after their position in alveolar bone crest is a procedure that has become popular in the last decade. The aim of this study is to evaluate the survival rate of 811 immediate loaded implants (ILIs). In the period between January 2008 and December 2013, 877 patients (498 females and 379 males) were operated at the BDD private Practice Clinic (Milan, Italy). The mean post-surgical follow-up was 30±17 months (max – min, 84 – 1). One thousasnd three hundred and eighty-six fixtures (EDIERRE Implant System SpA, Genoa, Italy) were evaluated in the present study, 811 immediately loaded and 575 loaded after 3 months. All patients underwent the same surgical protocol and agreed to participate in a post-operative check-up program. SPSS program was used for statistical analysis. Survival rate (SVR) was 97.3% since only 38 fixtures were lost from a total of 1,348 implants. Cross-tabulation between failures demonstrated slight but significant worse results for ILIs (p= 0.037). There were 28 failures out of 811 ILIs whereas only 10 fixtures were lost out of 565 implants loaded after 3 months. Immediate loading performed in selected cases is a reliable tool for oral rehabilitation. PMID:26511174

  19. Enhancement mode HEMT using fluorine implantation below the channel

    NASA Astrophysics Data System (ADS)

    Hamady, Saleem; Morancho, Frédéric; Beydoun, Bilal; Austin, Patrick; Gavelle, Mathieu

    2015-06-01

    Gallium nitride based high electron mobility transistors (HEMT) are powerful candidates for high frequency and high power applications. While switching applications demand normally-off operation, these devices are normally-on. Recent normally-off HEMTs were demonstrated by implanting fluorine above the channel, in the barrier layer. During implantation, fluorine ions penetrate into the channel and cause mobility degradation. In this paper, we propose and simulate an alternative approach in which fluorine ions are implanted below the channel of the HEMT rather than above it. The simulation tool ATLAS is calibrated using experimental data from a real HEMT device. Simulation results have shown that implanting fluorine ions below the channel is capable of achieving normally-off operation. When compared to the implantation in the barrier layer, the proposed approach offers better confinement for the two dimensional electron gas (2DEG) below the gate, eliminates the scattering of fluorine ions with channel electrons and is more efficient when it comes to the fluorine concentration required to achieve a desired threshold voltage. This technique neither affects the breakdown voltage nor the off-state current. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2014) - Elected submissions", edited by Adel Razek

  20. Nitinol Surfaces for Implantation

    NASA Astrophysics Data System (ADS)

    Shabalovskaya, Svetlana; Rondelli, Gianni; Rettenmayr, Markus

    2009-08-01

    Nitinol, a group of nearly equiatomic Ni-Ti alloys, steadily conquers new areas of application. Because of the need to keep a low profile of miniature implant devices, and considering the lack of compatibility between Nitinol superelasticity and the mechanical properties of traditional coatings, bare surfaces are of interest. In this article, an overview of our studies of bare Nitinol surfaces is presented, and the performance of coated surfaces is outlined. Together dense and porous Nitinol offer a wide array of surface topographies, suitable for attachment and migration of biological cells and tissue ingrowth. Native Nitinol surface oxides vary from amorphous to crystalline and exhibit semiconducting properties associated with better blood compatibility. Nitinol surfaces are analyzed with regard to high and lasting nickel release in vitro. Surface oxide thickness and Nitinol intermetallic particulates are discussed in relation to corrosion resistance and mechanical performance of the material.

  1. Transcatheter Aortic Valve Implantation.

    PubMed

    Malaisrie, S Chris; Iddriss, Adam; Flaherty, James D; Churyla, Andrei

    2016-05-01

    Severe aortic stenosis (AS) is a life-threatening condition when left untreated. Aortic valve replacement (AVR) is the gold standard treatment for the majority of patients; however, transcatheter aortic valve implantation/replacement (TAVI/TAVR) has emerged as the preferred treatment for high-risk or inoperable patients. The concept of transcatheter heart valves originated in the 1960s and has evolved into the current Edwards Sapien and Medtronic CoreValve platforms available for clinical use. Complications following TAVI, including cerebrovascular events, perivalvular regurgitation, vascular injury, and heart block have decreased with experience and evolving technology, such that ongoing trials studying TAVI in lower risk patients have become tenable. The multidisciplinary team involving the cardiac surgeon and cardiologist plays an essential role in patient selection, procedural conduct, and perioperative care. PMID:27021619

  2. Implantable, multifunctional, bioresorbable optics

    PubMed Central

    Tao, Hu; Kainerstorfer, Jana M.; Siebert, Sean M.; Pritchard, Eleanor M.; Sassaroli, Angelo; Panilaitis, Bruce J. B.; Brenckle, Mark A.; Amsden, Jason J.; Levitt, Jonathan; Fantini, Sergio; Kaplan, David L.; Omenetto, Fiorenzo G.

    2012-01-01

    Advances in personalized medicine are symbiotic with the development of novel technologies for biomedical devices. We present an approach that combines enhanced imaging of malignancies, therapeutics, and feedback about therapeutics in a single implantable, biocompatible, and resorbable device. This confluence of form and function is accomplished by capitalizing on the unique properties of silk proteins as a mechanically robust, biocompatible, optically clear biomaterial matrix that can house, stabilize, and retain the function of therapeutic components. By developing a form of high-quality microstructured optical elements, improved imaging of malignancies and of treatment monitoring can be achieved. The results demonstrate a unique family of devices for in vitro and in vivo use that provide functional biomaterials with built-in optical signal and contrast enhancement, demonstrated here with simultaneous drug delivery and feedback about drug delivery with no adverse biological effects, all while slowly degrading to regenerate native tissue. PMID:23150544

  3. Forecasting magnitude, time, and location of aftershocks for aftershock hazard

    NASA Astrophysics Data System (ADS)

    Chen, K.; Tsai, Y.; Huang, M.; Chang, W.

    2011-12-01

    In this study we investigate the spatial and temporal seismicity parameters of the aftershock sequence accompanying the 17:47 20 September 1999 (UTC) 7.45 Chi-Chi earthquake Taiwan. Dividing the epicentral zone into north of the epicenter, at the epicenter, and south of the epicenter, it is found that immediately after the earthquake the area close by the epicenter had a lower value than both the northern and southern sections. This pattern suggests that at the time of the Chi-Chi earthquake, the area close by the epicenter remained prone to large magnitude aftershocks and strong shaking. However, with time the value increases. An increasing value indicates a reduced likelihood of large magnitude aftershocks. The study also shows that the value is higher at the southern section of the epicentral zone, indicating a faster rate of decay in this section. The primary purpose of this paper is to design a predictive model for forecasting the magnitude, time, and location of aftershocks to large earthquakes. The developed model is presented and applied to the 17:47 20 September 1999 7.45 Chi-Chi earthquake Taiwan, and the 09:32 5 November 2009 (UTC) Nantou 6.19, and 00:18 4 March 2010 (UTC) Jiashian 6.49 earthquake sequences. In addition, peak ground acceleration trends for the Nantou and Jiashian aftershock sequences are predicted and compared to actual trends. The results of the estimated peak ground acceleration are remarkably similar to calculations from recorded magnitudes in both trend and level. To improve the predictive skill of the model for occurrence time, we use an empirical relation to forecast the time of aftershocks. The empirical relation improves time prediction over that of random processes. The results will be of interest to seismic mitigation specialists and rescue crews. We apply also the parameters and empirical relation from Chi-Chi aftershocks of Taiwan to forecast aftershocks with magnitude M > 6.0 of 05:46 11 March 2011 (UTC) Tohoku 9

  4. Software for goniometer control in the Triple Ion Implantation Facility

    SciTech Connect

    Allen, W.R.

    1994-02-01

    A computer program is described tat controls the goniometer employed in the ion scattering chamber of the Triple Ion Implantation Facility (TIF) in the Metals and Ceramics Division at Oak Ridge National Laboratory. Details of goniometer operation and its incorporation into the ion scattering setup specific to the TIF are also discussed.

  5. Infection control in implantation of cardiac implantable electronic devices: current evidence, controversial points, and unresolved issues.

    PubMed

    Korantzopoulos, Panagiotis; Sideris, Skevos; Dilaveris, Polychronis; Gatzoulis, Konstantinos; Goudevenos, John A

    2016-04-01

    A significant increase in the implantation of cardiac implantable electronic devices (CIEDs) is evident over the past years, while there is evidence for a disproportionate increase in CIED-related infections. The cumulative probability of device infection seems to be higher in implantable cardioverter defibrillator and in cardiac resynchronization therapy patients compared with permanent pacemaker patients. Given that more than a half of CIED infections are possibly related to the operative procedure, there is a need for effective periprocedural infection control. However, many of the current recommendations are empirical and not evidence-based, while questions, unresolved issues, and conflicting evidence arise. The perioperative systemic use of antibiotics confers significant benefit in prevention of CIED infections. However, there are no conclusive data regarding the specific value of each agent in different clinical settings, the value of post-operative antibiotic treatment as well as the optimal duration of therapy. The merit of local pocket irrigation with antibiotic and/or antiseptic agents remains unproved. Of note, recent evidence indicates that the application of antibacterial envelopes into the device pocket markedly decreases the infection risk. In addition, limited reports on strict integrated infection control protocols show a dramatic reduction in infection rates in this setting and therefore deserve further attention. Finally, the relative impact of particular factors on the infection risk, including the type of the CIED, patients' individual characteristics and comorbidities, should be further examined since it may facilitate the development of tailored prophylactic interventions for each patient. PMID:26516219

  6. How are number words mapped to approximate magnitudes?

    PubMed

    Sullivan, Jessica; Barner, David

    2013-01-01

    How do we map number words to the magnitudes they represent? While much is known about the developmental trajectory of number word learning, the acquisition of the counting routine, and the academic correlates of estimation ability, previous studies have yet to describe the mechanisms that link number words to nonverbal representations of number. We investigated two mechanisms: associative mapping and structure mapping. Four dot array estimation tasks found that adults' ability to match a number word to one of two discriminably different sets declined as a function of set size and that participants' estimates of relatively large, but not small, set sizes were influenced by misleading feedback during an estimation task. We propose that subjects employ structure mappings for linking relatively large number words to set sizes, but rely chiefly on item-by-item associative mappings for smaller sets. These results indicate that both inference and association play important roles in mapping number words to approximate magnitudes. PMID:22963174

  7. A Search for 23rd Magnitude Kuiper Belt Comets

    NASA Technical Reports Server (NTRS)

    Luu, Jane

    1997-01-01

    The goal of the project was to identify a statistically significant sample of large (200 km-sized) Kuiper Belt Objects (KBOs), by covering 10 sq. degrees of the sky to a red limiting magnitude m(sub R) = 23. This work differs from, but builds on, previous surveys of the outer solar system in that it will cover a large area to a limiting magnitude that is deep enough to guarantee positive results. The proposed work should provide us with a significant number of 200 km-size KBOs (approx. 20 are expected) for subsequent studies. Such a sample is crucial if we are to investigate the statistical properties of the Belt and its members. It was modified the original research strategy to accommodate unanticipated problems such as the urgent need for follow-up observations,the original goal was still reached: we have substantially increased the number of Kuiper Belt Objects brighter than 23rd mag.

  8. New methods for predicting the magnitude of sunspot maximum

    NASA Technical Reports Server (NTRS)

    Brown, G. M.

    1979-01-01

    Three new and independent methods of predicting the magnitude of a forthcoming sunspot maximum are suggested. The longest lead time is given by the first method, which is based on a terrestrial parameter measured during the declining phase of the preceding cycle. The second method, with only a slightly shorter foreknowledge, is based on an interplanetary parameter derived around the commencement of the cycle in question (sunspot minimum). The third method, giving the shortest prediction lead-time, is based entirely on solar parameters measured during the initial progress of the cycle in question. Application of all three methods to forecast the magnitude of the next maximum (Cycle 21) agree in predicting that it is likely to be very similar to that of Cycle 18.

  9. Sensori-motor spatial training of number magnitude representation.

    PubMed

    Fischer, Ursula; Moeller, Korbinian; Bientzle, Martina; Cress, Ulrike; Nuerk, Hans-Christoph

    2011-02-01

    An adequately developed spatial representation of number magnitude is associated with children's general arithmetic achievement. Therefore, a new spatial-numerical training program for kindergarten children was developed in which presentation and response were associated with a congruent spatial numerical representation. In particular, children responded by a full-body spatial movement on a digital dance mat in a magnitude comparison task. This spatial-numerical training was more effective than a non-spatial control training in enhancing children's performance on a number line estimation task and a subtest of a standardized mathematical achievement battery (TEDI-MATH). A mediation analysis suggested that these improvements were driven by an improvement of children's mental number line representation and not only by unspecific factors such as attention or motivation. These results suggest a benefit of spatial numerical associations. Rather than being a merely associated covariate, they work as an independently manipulated variable which is functional for numerical development. PMID:21327351

  10. Male chest enhancement: pectoral implants.

    PubMed

    Benito-Ruiz, J; Raigosa, J M; Manzano-Surroca, M; Salvador, L

    2008-01-01

    The authors present their experience with the pectoral muscle implant for male chest enhancement in 21 patients. The markings and technique are thoroughly described. The implants used were manufactured and custom made. The candidates for implants comprised three groups: group 1 (18 patients seeking chest enhancement), group 2 (1 patient with muscular atrophy), and group 3 (2 patients with muscular injuries). Because of the satisfying results obtained, including significant enhancement of the chest contour and no major complications, this technique is used for an increasing number of male cosmetic surgeries. PMID:17676376

  11. Pediatric cochlear implantation: an update.

    PubMed

    Vincenti, Vincenzo; Bacciu, Andrea; Guida, Maurizio; Marra, Francesca; Bertoldi, Barbara; Bacciu, Salvatore; Pasanisi, Enrico

    2014-01-01

    Deafness in pediatric age can adversely impact language acquisition as well as educational and social-emotional development. Once diagnosed, hearing loss should be rehabilitated early; the goal is to provide the child with maximum access to the acoustic features of speech within a listening range that is safe and comfortable. In presence of severe to profound deafness, benefit from auditory amplification cannot be enough to allow a proper language development. Cochlear implants are partially implantable electronic devices designed to provide profoundly deafened patients with hearing sensitivity within the speech range. Since their introduction more than 30 years ago, cochlear implants have improved their performance to the extent that are now considered to be standard of care in the treatment of children with severe to profound deafness. Over the years patient candidacy has been expanded and the criteria for implantation continue to evolve within the paediatric population. The minimum age for implantation has progressively reduced; it has been recognized that implantation at a very early age (12-18 months) provides children with the best outcomes, taking advantage of sensitive periods of auditory development. Bilateral implantation offers a better sound localization, as well as a superior ability to understand speech in noisy environments than unilateral cochlear implant. Deafened children with special clinical situations, including inner ear malformation, cochlear nerve deficiency, cochlear ossification, and additional disabilities can be successfully treated, even thogh they require an individualized candidacy evaluation and a complex post-implantation rehabilitation. Benefits from cochlear implantation include not only better abilities to hear and to develop speech and language skills, but also improved academic attainment, improved quality of life, and better employment status. Cochlear implants permit deaf people to hear, but they have a long way to go before

  12. Silicone breast implants and platinum.

    PubMed

    Wixtrom, Roger N

    2007-12-01

    Platinum, in a specific form, is used as a catalyst in the cross-linking reactions of the silicone gel and elastomer in breast implants. After manufacture, it remains in the devices at low-parts-per-million levels. Potential concerns have been raised as to whether this platinum might diffuse from silicone breast implants into the body and result in adverse health effects. The weight of evidence indicates that the platinum present is in its most biocompatible (zero valence) form, and the very minute levels (<0.1 percent) that might diffuse from the implants do not represent a significant health risk to patients. PMID:18090821

  13. MAGNITUDE GAP STATISTICS AND THE CONDITIONAL LUMINOSITY FUNCTION

    SciTech Connect

    More, Surhud

    2012-12-20

    In a recent preprint, Hearin et al. (H12) suggest that the halo mass-richness calibration of clusters can be improved by using the difference in the magnitude of the brightest and the second brightest galaxy (magnitude gap) as an additional observable. They claim that their results are at odds with the results from Paranjape and Sheth (PS12) who show that the magnitude distribution of the brightest and second brightest galaxies can be explained based on order statistics of luminosities randomly sampled from the total galaxy luminosity function. We find that a conditional luminosity function (CLF) for galaxies which varies with halo mass, in a manner which is consistent with existing observations, naturally leads to a magnitude gap distribution which changes as a function of halo mass at fixed richness, in qualitative agreement with H12. We show that, in general, the luminosity distribution of the brightest and the second brightest galaxy depends upon whether the luminosities of galaxies are drawn from the CLF or the global luminosity function. However, we also show that the difference between the two cases is small enough to evade detection in the small sample investigated by PS12. This shows that the luminosity distribution is not the appropriate statistic to distinguish between the two cases, given the small sample size. We argue in favor of the CLF (and therefore H12) based upon its consistency with other independent observations, such as the kinematics of satellite galaxies, the abundance and clustering of galaxies, and the galaxy-galaxy lensing signal from the Sloan Digital Sky Survey.

  14. THE ABSOLUTE MAGNITUDES OF TYPE Ia SUPERNOVAE IN THE ULTRAVIOLET

    SciTech Connect

    Brown, Peter J.; Roming, Peter W. A.; Ciardullo, Robin; Gronwall, Caryl; Hoversten, Erik A.; Pritchard, Tyler; Milne, Peter; Bufano, Filomena; Mazzali, Paolo; Elias-Rosa, Nancy; Filippenko, Alexei V.; Li Weidong; Foley, Ryan J.; Hicken, Malcolm; Kirshner, Robert P.; Gehrels, Neil; Holland, Stephen T.; Immler, Stefan; Phillips, Mark M.; Still, Martin

    2010-10-01

    We examine the absolute magnitudes and light-curve shapes of 14 nearby (redshift z = 0.004-0.027) Type Ia supernovae (SNe Ia) observed in the ultraviolet (UV) with the Swift Ultraviolet/Optical Telescope. Colors and absolute magnitudes are calculated using both a standard Milky Way extinction law and one for the Large Magellanic Cloud that has been modified by circumstellar scattering. We find very different behavior in the near-UV filters (uvw1{sub rc} covering {approx}2600-3300 A after removing optical light, and u {approx} 3000-4000 A) compared to a mid-UV filter (uvm2 {approx}2000-2400 A). The uvw1{sub rc} - b colors show a scatter of {approx}0.3 mag while uvm2-b scatters by nearly 0.9 mag. Similarly, while the scatter in colors between neighboring filters is small in the optical and somewhat larger in the near-UV, the large scatter in the uvm2 - uvw1 colors implies significantly larger spectral variability below 2600 A. We find that in the near-UV the absolute magnitudes at peak brightness of normal SNe Ia in our sample are correlated with the optical decay rate with a scatter of 0.4 mag, comparable to that found for the optical in our sample. However, in the mid-UV the scatter is larger, {approx}1 mag, possibly indicating differences in metallicity. We find no strong correlation between either the UV light-curve shapes or the UV colors and the UV absolute magnitudes. With larger samples, the UV luminosity might be useful as an additional constraint to help determine distance, extinction, and metallicity in order to improve the utility of SNe Ia as standardized candles.

  15. Can we test for the maximum possible earthquake magnitude?

    NASA Astrophysics Data System (ADS)

    Holschneider, M.; Zöller, G.; Clements, R.; Schorlemmer, D.

    2014-03-01

    We explore the concept of maximum possible earthquake magnitude, M, in a region represented by an earthquake catalog from the viewpoint of statistical testing. For this aim, we assume that earthquake magnitudes are independent events that follow a doubly truncated Gutenberg-Richter distribution and focus on the upper truncation M. In earlier work, it has been shown that the value of M cannot be well constrained from earthquake catalogs alone. However, for two hypothesized values M and M', alternative statistical tests may address the question: Which value is more consistent with the data? In other words, is it possible to reject a magnitude within reasonable errors, i.e., the error of the first and the error of the second kind? The results for realistic settings indicate that either the error of the first kind or the error of the second kind is intolerably large. We conclude that it is essentially impossible to infer M in terms of alternative testing with sufficient confidence from an earthquake catalog alone, even in regions like Japan with excellent data availability. These findings are also valid for frequency-magnitude distributions with different tail behavior, e.g., exponential tapering. Finally, we emphasize that different data may only be useful to provide additional constraints for M, if they do not correlate with the earthquake catalog, i.e., if they have not been recorded in the same observational period. In particular, long-term geological assessments might be suitable to reduce the errors, while GPS measurements provide overall the same information as the catalogs.

  16. 21 CFR 522.1350 - Melatonin implant.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Melatonin implant. 522.1350 Section 522.1350 Food... Melatonin implant. (a) Specifications. The drug is a silicone rubber elastomer implant containing 2.7...—(1) Amount. One implant per mink. (2) Indications for use. For use in healthy male and female kit...

  17. 21 CFR 522.1350 - Melatonin implant.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Melatonin implant. 522.1350 Section 522.1350 Food... Melatonin implant. (a) Specifications. The drug is a silicone rubber elastomer implant containing 2.7...—(1) Amount. One implant per mink. (2) Indications for use. For use in healthy male and female kit...

  18. 21 CFR 522.1350 - Melatonin implant.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Melatonin implant. 522.1350 Section 522.1350 Food... Melatonin implant. (a) Specifications. The drug is a silicone rubber elastomer implant containing 2.7...—(1) Amount. One implant per mink. (2) Indications for use. For use in healthy male and female kit...

  19. 21 CFR 522.1350 - Melatonin implant.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Melatonin implant. 522.1350 Section 522.1350 Food... Melatonin implant. (a) Specifications. The drug is a silicone rubber elastomer implant containing 2.7...—(1) Amount. One implant per mink. (2) Indications for use. For use in healthy male and female kit...

  20. Occlusion on oral implants: current clinical guidelines.

    PubMed

    Koyano, K; Esaki, D

    2015-02-01

    Proper implant occlusion is essential for adequate oral function and the prevention of adverse consequences, such as implant overloading. Dental implants are thought to be more prone to occlusal overloading than natural teeth because of the loss of the periodontal ligament, which provides shock absorption and periodontal mechanoreceptors, which provide tactile sensitivity and proprioceptive motion feedback. Although many guidelines and theories on implant occlusion have been proposed, few have provided strong supportive evidence. Thus, we performed a narrative literature review to ascertain the influence of implant occlusion on the occurrence of complications of implant treatment and discuss the clinical considerations focused on the overloading factors at present. The search terms were 'dental implant', 'dental implantation', 'dental occlusion' and 'dental prosthesis'. The inclusion criteria were literature published in English up to September 2013. Randomised controlled trials (RCTs), prospective cohort studies and case-control studies with at least 20 cases and 12 months follow-up interval were included. Based on the selected literature, this review explores factors related to the implant prosthesis (cantilever, crown/implant ratio, premature contact, occlusal scheme, implant-abutment connection, splinting implants and tooth-implant connection) and other considerations, such as the number, diameter, length and angulation of implants. Over 700 abstracts were reviewed, from which more than 30 manuscripts were included. We found insufficient evidence to establish firm clinical guidelines for implant occlusion. To discuss the ideal occlusion for implants, further well-designed RCTs are required in the future. PMID:25284468

  1. "Rules of 10"--guidelines for successful planning and treatment of mandibular edentulism using dental implants.

    PubMed

    Cooper, Lyndon F; Limmer, Bryan M; Gates, W Day

    2012-05-01

    The three "Rules of 10" for treatment planning dental implant therapy in the edentulous mandible are designed to improve the success of both the endosseous implants and the prosthesis. These "rules" acknowledge and provide a method to control the mechanical environment, addressing factors affecting implant and prosthesis longevity, including magnitude of forces, resistance of the prosthesis against these forces, and the biology of bone and its ability to respond to loading environments. The rules specify that for any IRO or ISFP, there must be a minimum of 10 mm of alveolar dimension (inferior/superior) and a minimum of 10 mm of interocclusal (restorative) dimension measured from the soft-tissue ridge crest to the occlusal plane. Additionally, for an ISFP, the anterior/posterior distribution of implants must be greater than 10 mm. This article provides support in the literature for these rules and illustrates their application in the treatment of mandibular edentulism. PMID:22616215

  2. Cochlear implant speech processor placement and compression effects on sound sensitivity and interaural level difference.

    PubMed

    Ricketts, Todd; Grantham, D Wesley; D'Haese, Patrick; Edwards, Jason; Barco, Amy

    2006-02-01

    The purpose of this investigation was to determine the impact of commonly recommended cochlear implant (CI) speech processor placements on microphone output both with and without single channel front-end compression. The impact of this compression use on interaural level difference (ILD) magnitude was also evaluated for the ear-level position. Finally, pilot localization data collected with and without single channel front-end compression was collected on seven bilateral cochlear implant recipients. The results revealed that differences in signal audibility due to clinical placement of CI speech processors in ear, shoulder, and collar positions can at least partially be offset through the use of front-end compression. These data also revealed that compression impacted ILD cues. Preliminary data indicated that some bilaterally implanted subjects were able to take advantage of the enhanced ILD cues when compression was turned off, while other bilaterally implanted subjects did not localize better in the compression-off condition. PMID:16640065

  3. The magnitude-redshift relation for 561 Abell clusters

    NASA Technical Reports Server (NTRS)

    Postman, M.; Huchra, J. P.; Geller, M. J.; Henry, J. P.

    1985-01-01

    The Hubble diagram for the 561 Abell clusters with measured redshifts has been examined using Abell's (1958) corrected photo-red magnitudes for the tenth-ranked cluster member (m10). After correction for the Scott effect and K dimming, the data are in good agreement with a linear magnitude-redshift relation with a slope of 0.2 out to z = 0.1. New redshift data are also presented for 20 Abell clusters. Abell's m10 is suitable for redshift estimation for clusters with m10 of no more than 16.5. At fainter m10, the number of foreground galaxies expected within an Abell radius is large enough to make identification of the tenth-ranked galaxy difficult. Interlopers bias the estimated redshift toward low values at high redshift. Leir and van den Bergh's (1977) redshift estimates suffer from this same bias but to a smaller degree because of the use of multiple cluster parameters. Constraints on deviations of cluster velocities from the mean cosmological flow require greater photometric accuracy than is provided by Abell's m10 magnitudes.

  4. Typical magnitude and spatial extent of crowding in autism

    PubMed Central

    Freyberg, Jan; Robertson, Caroline E.; Baron-Cohen, Simon

    2016-01-01

    Enhanced spatial processing of local visual details has been reported in individuals with autism spectrum conditions (ASC), and crowding is postulated to be a mechanism that may produce this ability. However, evidence for atypical crowding in ASC is mixed, with some studies reporting a complete lack of crowding in autism and others reporting a typical magnitude of crowding between individuals with and without ASC. Here, we aim to disambiguate these conflicting results by testing both the magnitude and the spatial extent of crowding in individuals with ASC (N = 25) and age- and IQ-matched controls (N = 23) during an orientation discrimination task. We find a strong crowding effect in individuals with and without ASC, which falls off as the distance between target and flanker is increased. Both the magnitude and the spatial range of this effect were comparable between individuals with and without ASC. We also find typical (uncrowded) orientation discrimination thresholds in individuals with ASC. These findings suggest that the spatial extent of crowding is unremarkable in ASC, and is therefore unlikely to account for the visual symptoms reported in individuals with the diagnosis. PMID:26998801

  5. The Road to Convergence in Earthquake Frequency-Magnitude Statistics

    NASA Astrophysics Data System (ADS)

    Naylor, M.; Bell, A. F.; Main, I. G.

    2013-12-01

    The Gutenberg-Richter frequency-magnitude relation is a fundamental empirical law of seismology, but its form remains uncertain for rare extreme events. Convergence trends can be diagnostic of the nature of an underlying distribution and its sampling even before convergence has occurred. We examine the evolution of an information criteria metric applied to earthquake magnitude time series, in order to test whether the Gutenberg-Richter law can be rejecting in various earthquake catalogues. This would imply that the catalogue is starting to sample roll-off in the tail though it cannot yet identify the form of the roll-off. We compare bootstrapped synthetic Gutenberg-Richter and synthetic modified Gutenberg-Richter catalogues with the convergence trends observed in real earthquake data e.g. the global CMT catalogue, Southern California and mining/geothermal data. Whilst convergence in the tail remains some way off, we show that the temporal evolution of model likelihoods and parameters for the frequency-magnitude distribution of the global Harvard Centroid Moment Tensor catalogue is inconsistent with an unbounded GR relation, despite it being the preferred model at the current time. Bell, A. F., M. Naylor, and I. G. Main (2013), Convergence of the frequency-size distribution of global earthquakes, Geophys. Res. Lett., 40, 2585-2589, doi:10.1002/grl.50416.

  6. Magnitudes and timescales of total solar irradiance variability

    NASA Astrophysics Data System (ADS)

    Kopp, Greg

    2016-07-01

    The Sun's net radiative output varies on timescales of minutes to gigayears. Direct measurements of the total solar irradiance (TSI) show changes in the spatially- and spectrally-integrated radiant energy on timescales as short as minutes to as long as a solar cycle. Variations of ~0.01% over a few minutes are caused by the ever-present superposition of convection and oscillations with very large solar flares on rare occasion causing slightly-larger measurable signals. On timescales of days to weeks, changing photospheric magnetic activity affects solar brightness at the ~0.1% level. The 11-year solar cycle shows variations of comparable magnitude with irradiances peaking near solar maximum. Secular variations are more difficult to discern, being limited by instrument stability and the relatively short duration of the space-borne record. Historical reconstructions of the Sun's irradiance based on indicators of solar-surface magnetic activity, such as sunspots, faculae, and cosmogenic isotope records, suggest solar brightness changes over decades to millennia, although the magnitudes of these variations have high uncertainties due to the indirect historical records on which they rely. Stellar evolution affects yet longer timescales and is responsible for the greatest solar variabilities. In this manuscript I summarize the Sun's variability magnitudes over different temporal regimes and discuss the irradiance record's relevance for solar and climate studies as well as for detections of exo-solar planets transiting Sun-like stars.

  7. Correlating precursory declines in groundwater radon with earthquake magnitude.

    PubMed

    Kuo, T

    2014-01-01

    Both studies at the Antung hot spring in eastern Taiwan and at the Paihe spring in southern Taiwan confirm that groundwater radon can be a consistent tracer for strain changes in the crust preceding an earthquake when observed in a low-porosity fractured aquifer surrounded by a ductile formation. Recurrent anomalous declines in groundwater radon were observed at the Antung D1 monitoring well in eastern Taiwan prior to the five earthquakes of magnitude (Mw ): 6.8, 6.1, 5.9, 5.4, and 5.0 that occurred on December 10, 2003; April 1, 2006; April 15, 2006; February 17, 2008; and July 12, 2011, respectively. For earthquakes occurring on the longitudinal valley fault in eastern Taiwan, the observed radon minima decrease as the earthquake magnitude increases. The above correlation has been proven to be useful for early warning local large earthquakes. In southern Taiwan, radon anomalous declines prior to the 2010 Mw 6.3 Jiasian, 2012 Mw 5.9 Wutai, and 2012 ML 5.4 Kaohsiung earthquakes were also recorded at the Paihe spring. For earthquakes occurring on different faults in southern Taiwan, the correlation between the observed radon minima and the earthquake magnitude is not yet possible. PMID:23550908

  8. Hybrid Modelling of the Economical Consequences of Extreme Magnitude Earthquakes

    NASA Astrophysics Data System (ADS)

    Chavez, M.; Cabrera, E.; Ashworth, M.; Garcia, S.; Emerson, D.; Perea, N.; Salazar, A.; Moulinec, C.

    2013-05-01

    A hybrid modelling methodology is proposed to estimate the probability of exceedance of the intensities of extreme magnitude earthquakes (PEI) and of their direct economical consequences (PEDEC). The hybrid modeling uses 3D seismic wave propagation (3DWP) combined with empirical Green function (EGF) and Neural Network (NN) techniques in order to estimate the seismic hazard (PEIs) of extreme earthquakes (plausible) scenarios corresponding to synthetic seismic sources. The 3DWP modeling is achieved by using a 3D finite difference code run in the ~100 thousands cores Blue Gene Q supercomputer of the STFC Daresbury Laboratory of UK. The PEDEC are computed by using appropriate vulnerability functions combined with the scenario intensity samples, and Monte Carlo simulation. The methodology is validated for Mw 8 magnitude subduction events, and show examples of its application for the estimation of the hazard and the economical consequences, for extreme Mw 8.5 subduction earthquake scenarios with seismic sources in the Mexican Pacific Coast. The results obtained with the proposed methodology, such as those of the PEDECs in terms of the joint event "damage Cost (C) - maximum ground intensities", of the conditional return period of C given that the maximum intensity exceeds a certain value, could be used by decision makers to allocate funds or to implement policies, to mitigate the impact associated to the plausible occurrence of future extreme magnitude earthquakes.

  9. Regional moment: Magnitude relations for earthquakes and explosions

    SciTech Connect

    Patton, H.J.; Walter, W.R. )

    1993-02-19

    The authors present M[sub o]:m[sub b] relations using m[sub b](P[sub n]) and m[sub b](L[sub g]) for earthquakes and explosions occurring in tectonic and stable areas. The observations for m[sub b](P[sub n]) range from about 3 to 6 and show excellent separation between earthquakes and explosions on M[sub o]:m[sub b] plots, independent of the magnitude. The scatter in M[sub o]:M[sub b] observations for NTS explosions is small compared to the earthquake data. The M[sub o]:m[sub b](L[sub g]) data for Soviet explosions overlay the observations for US explosions. These results, and the small scatter for NTS explosions, suggest weak dependence of M[sub o]:m[sub b] relations on emplacement media. A simple theoretical model is developed which matches all these observations. The model uses scaling similarity and conservation of energy to provide a physical link between seismic moment and a broadband seismic magnitude. Three factors, radiation pattern, material property, and apparent stress, contribute to the separation between earthquakes and explosions. This theoretical separation is independent of broadband magnitude. For US explosions in different media, the material property and apparent stress contributions are shown to compensate for one another, supporting the observations that M[sub o]:M[sub b] is nearly independent of source geology. 19 refs., 2 figs., 1 tab.

  10. The magnitude-redshift relation in a realistic inhomogeneous universe

    SciTech Connect

    Hada, Ryuichiro; Futamase, Toshifumi E-mail: tof@astr.tohoku.ac.jp

    2014-12-01

    The light rays from a source are subject to a local inhomogeneous geometry generated by inhomogeneous matter distribution as well as the existence of collapsed objects. In this paper we investigate the effect of inhomogeneities and the existence of collapsed objects on the propagation of light rays and evaluate changes in the magnitude-redshift relation from the standard relationship found in a homogeneous FRW universe. We give the expression of the correlation function and the variance for the perturbation of apparent magnitude, and calculate it numerically by using the non-linear matter power spectrum. We use the lognormal probability distribution function for the density contrast and spherical collapse model to truncate the power spectrum in order to estimate the blocking effect by collapsed objects. We find that the uncertainties in Ω{sub m} is ∼ 0.02, and that of w is ∼ 0.04 . We also discuss a possible method to extract these effects from real data which contains intrinsic ambiguities associated with the absolute magnitude.

  11. Threshold magnitudes for a multichannel correlation detector in background seismicity

    DOE PAGESBeta

    Carmichael, Joshua D.; Hartse, Hans

    2016-04-01

    Colocated explosive sources often produce correlated seismic waveforms. Multichannel correlation detectors identify these signals by scanning template waveforms recorded from known reference events against "target" data to find similar waveforms. This screening problem is challenged at thresholds required to monitor smaller explosions, often because non-target signals falsely trigger such detectors. Therefore, it is generally unclear what thresholds will reliably identify a target explosion while screening non-target background seismicity. Here, we estimate threshold magnitudes for hypothetical explosions located at the North Korean nuclear test site over six months of 2010, by processing International Monitoring System (IMS) array data with a multichannelmore » waveform correlation detector. Our method (1) accounts for low amplitude background seismicity that falsely triggers correlation detectors but is unidentifiable with conventional power beams, (2) adapts to diurnally variable noise levels and (3) uses source-receiver reciprocity concepts to estimate thresholds for explosions spatially separated from the template source. Furthermore, we find that underground explosions with body wave magnitudes mb = 1.66 are detectable at the IMS array USRK with probability 0.99, when using template waveforms consisting only of P -waves, without false alarms. We conservatively find that these thresholds also increase by up to a magnitude unit for sources located 4 km or more from the Feb.12, 2013 announced nuclear test.« less

  12. Improved instrumental magnitude prediction expected from version 2 of the NASA SKY2000 master star catalog

    NASA Technical Reports Server (NTRS)

    Sande, C. B.; Brasoveanu, D.; Miller, A. C.; Home, A. T.; Tracewell, D. A.; Warren, W. H., Jr.

    1998-01-01

    The SKY2000 Master Star Catalog (MC), Version 2 and its predecessors have been designed to provide the basic astronomical input data needed for satellite acquisition and attitude determination on NASA spacecraft. Stellar positions and proper motions are the primary MC data required for operations support followed closely by the stellar brightness observed in various standard astronomical passbands. The instrumental red-magnitude prediction subsystem (REDMAG) in the MMSCAT software package computes the expected instrumental color index (CI) [sensor color correction] from an observed astronomical stellar magnitude in the MC and the characteristics of the stellar spectrum, astronomical passband, and sensor sensitivity curve. The computation is more error prone the greater the mismatch of the sensor sensitivity curve characteristics and those of the observed astronomical passbands. This paper presents the preliminary performance analysis of a typical red-sensitive CCDST during acquisition of sensor data from the two Ball CT-601 ST's onboard the Rossi X-Ray Timing Explorer (RXTE). A comparison is made of relative star positions measured in the ST FOV coordinate system with the expected results computed from the recently released Tycho Catalogue. The comparison is repeated for a group of observed stars with nearby, bright neighbors in order to determine the tracker behavior in the presence of an interfering, near neighbor (NN). The results of this analysis will be used to help define a new photoelectric photometric instrumental sensor magnitude system (S) that is based on several thousand bright star magnitudes observed with the PXTE ST's. This new system will be implemented in Version 2 of the SKY2000 MC to provide improved predicted magnitudes in the mission run catalogs.

  13. Mechanisms of Focused Ion Beam Implantation Damage and Recovery in Si

    NASA Astrophysics Data System (ADS)

    Balasubramanian, G. P. S.; Hull, R.

    2016-06-01

    The ion current density in focused ion beam (FIB) systems, 0.1-10 A cm-2, is at least three orders of magnitude greater than that in commercial broad ion beam implanters. This large difference in ion current density is expected to strongly affect the damage recovery dynamics. In this work, we study the ion implantation damage and recovery of Si(100) substrates implanted with 1 × 1012-5 × 1015 Si cm-2 fluences of 60-keV Si2+ at normal incidence in a mass-selecting FIB. Additionally, damage and recovery in different broad ion beam implants of 60-keV Si+ were studied for a comparison. For recovering implantation damage, specimens were annealed for different times at 730-900°C in an ultra-high purity nitrogen ambient, and for characterizing damage and recovery, Raman spectroscopy at wavelengths 405 nm and 514 nm was carried out. Raman measurements comprised of measurements of crystalline Si (c-Si) peak height of the peak at 520 cm-1, and the peak shift relative to that of un-implanted reference Si. Our measurements of structural damage—calculated from the attenuation in the c-Si peak heights for the implants relative to that of unimplanted Si(100)—indicates that the FIB implantations lead to a greater as-implanted damage but also typically lead to a better recovery than that for the commercial broad-area implants. The underlying mechanisms for these observations are discussed.

  14. Does low magnitude earthquake ground shaking cause landslides?

    NASA Astrophysics Data System (ADS)

    Brain, Matthew; Rosser, Nick; Vann Jones, Emma; Tunstall, Neil

    2015-04-01

    Estimating the magnitude of coseismic landslide strain accumulation at both local and regional scales is a key goal in understanding earthquake-triggered landslide distributions and landscape evolution, and in undertaking seismic risk assessment. Research in this field has primarily been carried out using the 'Newmark sliding block method' to model landslide behaviour; downslope movement of the landslide mass occurs when seismic ground accelerations are sufficient to overcome shear resistance at the landslide shear surface. The Newmark method has the advantage of simplicity, requiring only limited information on material strength properties, landslide geometry and coseismic ground motion. However, the underlying conceptual model assumes that shear strength characteristics (friction angle and cohesion) calculated using conventional strain-controlled monotonic shear tests are valid under dynamic conditions, and that values describing shear strength do not change as landslide shear strain accumulates. Recent experimental work has begun to question these assumptions, highlighting, for example, the importance of shear strain rate and changes in shear strength properties following seismic loading. However, such studies typically focus on a single earthquake event that is of sufficient magnitude to cause permanent strain accumulation; by doing so, they do not consider the potential effects that multiple low-magnitude ground shaking events can have on material strength. Since such events are more common in nature relative to high-magnitude shaking events, it is important to constrain their geomorphic effectiveness. Using an experimental laboratory approach, we present results that address this key question. We used a bespoke geotechnical testing apparatus, the Dynamic Back-Pressured Shear Box (DynBPS), that uniquely permits more realistic simulation of earthquake ground-shaking conditions within a hillslope. We tested both cohesive and granular materials, both of which

  15. Patients with pacemaker or implantable cardioverter-defibrillator.

    PubMed

    Schulman, Peter M; Rozner, Marc A; Sera, Valerie; Stecker, Eric C

    2013-11-01

    The preparation of patients with a cardiac implantable electronic device (CIED) for the perioperative period necessitates familiarity with recommendations from the American Society of Anesthesiologists and Heart Rhythm Society. Even clinicians who are not CIED experts should understand the indications for implantation, as well as the basic functions, operations, and limitations of these devices. Before any scheduled procedure, proper CIED function should be verified and a specific CIED prescription obtained. Acquiring the requisite knowledge base and developing the systems to competently manage the CIED patient ensures safe and efficient perioperative care. PMID:24182719

  16. A feasibility study of ion implantation techniques for mass spectrometer calibration

    NASA Technical Reports Server (NTRS)

    Koslin, M. E.; Krycuk, G. A.; Schatz, J. G., Jr.; White, F. A.; Wood, G. M.

    1978-01-01

    An experimental study was undertaken to examine the feasibility of using ion-implanted filaments doped with either an alkali metal or noble gas for in situ recalibration of onboard mass spectrometers during extended space missions. Implants of rubidium and krypton in rhenium ribbon filaments were subsequently tested in a bakeable 60 deg sector mass spectrometer operating in the static mode. Surface ionization and electron impact ion sources were both used, each yielding satisfactory results. The metallic implant with subsequent ionization provided a means of mass scale calibration and determination of system operating parameters, whereas the noble gas thermally desorbed into the system was more suited for partial pressure and sensitivity determinations.

  17. The robo-pigeon based on the multiple brain regions synchronization implanted microelectrodes.

    PubMed

    Huai, Rui-Tuo; Yang, Jun-Qing; Wang, Hui

    2016-07-01

    Almost all multichannel microelectrodes are only applied to the same nucleus. The multiple brain regions synchronization implanted microelectrodes can be implanted in the several brain regions at the same time, when used in the robo-animal, which can reduce the operation process, shorten animals operation time. Due to electrode position relatively fixed, errors caused by each separately implanted electrode were reduced and the animal control effect was greatly increased compared to the original electrodes. The electrode fixed time was also extended. This microelectrode provided beneficial reference function for the study of the free state of small animals in different brain regions. PMID:27459594

  18. Mini Implants Supporting Fixed Partial Dentures in the Posterior Mandible: A Retrospective.

    PubMed

    Flanagan, Dennis

    2015-08-01

    Small-diameter, or mini, dental implants have been successfully used to support removable and fixed oral prostheses. These implants impart about twice the per-square-millimeter force on the supporting bone and this should be addressed during treatment planning. In the posterior jaws, bite forces are of a higher magnitude than in the anterior jaws and may induce an overload of the supporting bone and failure of the osseointegration. Thus there should not be occlusal contact in functional excursions that induce off axial loads. The cases presented herein demonstrate that mini dental implants may be used successfully to support fixed partial dentures in mandibular sites in highly selected patients. Attention should be given to the bone density of the site, very slow seating rotation of the implant with intermissions or cooling during insertion, observation of a 4-month healing time, flapless placement, treatment of any existing periodontitis, an insoluble cement, and exclusion of occlusal contact in functional excursions. Importantly, a narrow, rounded occlusal table should be used to minimize off axial loads and an insoluble luting cement should be used to prevent loosening of the crowns due to dissolution of the cement and an overload of the retained implant with any residual cement-retained in the retainer. The implant that supports the cement retained retainer will be subjected to leveraged rotation that may destroy the osseointegration and result in exfoliation of the implant. PMID:24779887

  19. Convex optimization of MRI exposure for mitigation of RF-heating from active medical implants

    NASA Astrophysics Data System (ADS)

    Córcoles, Juan; Zastrow, Earl; Kuster, Niels

    2015-09-01

    Local RF-heating of elongated medical implants during magnetic resonance imaging (MRI) may pose a significant health risk to patients. The actual patient risk depends on various parameters including RF magnetic field strength and frequency, MR coil design, patient’s anatomy, posture, and imaging position, implant location, RF coupling efficiency of the implant, and the bio-physiological responses associated with the induced local heating. We present three constrained convex optimization strategies that incorporate the implant’s RF-heating characteristics, for the reduction of local heating of medical implants during MRI. The study emphasizes the complementary performances of the different formulations. The analysis demonstrates that RF-induced heating of elongated metallic medical implants can be carefully controlled and balanced against MRI quality. A reduction of heating of up to 25 dB can be achieved at the cost of reduced uniformity in the magnitude of the B1+ field of less than 5%. The current formulations incorporate a priori knowledge of clinically-specific parameters, which is assumed to be available. Before these techniques can be applied practically in the broader clinical context, further investigations are needed to determine whether reduced access to a priori knowledge regarding, e.g. the patient’s anatomy, implant routing, RF-transmitter, and RF-implant coupling, can be accepted within reasonable levels of uncertainty.

  20. [Imaging in silicone breast implantation].

    PubMed

    Gielens, Maaike P M; Koolen, Pieter G L; Hermens, Roland A E C; Rutten, Matthieu J C M

    2013-01-01

    Recently, there have been concerns regarding the use of breast implants from Poly Implant Prothèse (PIP, Seyne sur Mer, France) for breast augmentation due to their tendency to rupture and the possibility of having toxic contents. MRI using a specific silicone-sensitive sequence has proven to be the most sensitive and specific technique in the detection of intra- and extracapsular implant rupture. However, given its high costs, it is important that this technique is used sparingly. In this clinical lesson, we compare the sensitivity and specificity of mammography, ultrasound, CT and MRI for the detection of breast implant rupture. Based on two cases, a diagnostic approach is given in order to reduce health care costs. PMID:24252405

  1. ANTIARRHYTHMICS VERSUS IMPLANTABLE DEFIBRILLATORS (AVID)

    EPA Science Inventory

    Evaluates whether use of an implantable cardiac defibrillator (ICD) results in reduction in total mortality, when compared with conventional pharmacological therapy, in patients resuscitated from sudden cardiac death who are otherwise at very high risk of mortality from arrhythmi...

  2. [A totally implantable hearing aid for inner ear deafness: TICA LZ 3001].

    PubMed

    Leysieffer, H; Baumann, J W; Mayer, R; Müller, D; Müller, G; Schön, T; Volz, A; Zenner, H P

    1998-10-01

    Recently, Zenner et al. implanted the first totally implantable electronic hearing devices in patients with SNHL (HNO 46 [1998] 844-852). In the present report, technical and audiological features of the implant TICA are published. The development of the piezoelectric transducer and the microphone for implantation in the posterior wall of the auditory canal as components for the present fully implantable hearing system has already been described (HNO 45, 1997, 792-880). Here we report about our experience with the electronic main module that completes the TICA LZ 3001 system. This module is suited for implantation in the mastoid bone and contains the signal-processing electronics and an integrated battery that can be recharged transcutaneously with a portable charger. The recharging time is around 2 h for an implant operating time of 50 h. The microphone and transducer connectors allow for easy replacement of the main module when the battery lifetime is reached. This lifetime is around 3-5 years. A small wireless remote control allows volume adjustment, contains an on/off switch, and permits selection of four different individual hearing programs. The basic audiological features are provided by a flexible, digitally programmable 3-channel-AGC-system with a peak clipping function. The total bandwidth is around 10 kHz. To our knowledge this is the first fully implantable hearing system that has been in implanted in humans. PMID:9846265

  3. Fiber implantation for pattern baldness.

    PubMed

    Hanke, C W; Bergfeld, W F

    1979-01-12

    Examination of 20 patients who had fiber implantation for the treatment of pattern baldness showed that nearly all the fibers had fallen out by ten weeks. Complications observed were facial swelling, infection, foreign-body granulomas, scarring, and permanent hair loss. Scanning electron microscopy identified the fibers as modacrylic fibers. The complications, high monetary cost, and ultimate futility of fiber implantation make it an unacceptable procedure. PMID:364078

  4. In vivo stimulation of bone formation by aluminum and oxygen plasma surface-modified magnesium implants.

    PubMed

    Wong, Hoi Man; Zhao, Ying; Tam, Vivian; Wu, Shuilin; Chu, Paul K; Zheng, Yufeng; To, Michael Kai Tsun; Leung, Frankie K L; Luk, Keith D K; Cheung, Kenneth M C; Yeung, Kelvin W K

    2013-12-01

    A newly developed magnesium implant is used to stimulate bone formation in vivo. The magnesium implant after undergoing dual aluminum and oxygen plasma implantation is able to suppress rapid corrosion, leaching of magnesium ions, as well as hydrogen gas release from the biodegradable alloy in simulated body fluid (SBF). No released aluminum is detected from the SBF extract and enhanced corrosion resistance properties are confirmed by electrochemical tests. In vitro studies reveal enhanced growth of GFP mouse osteoblasts on the aluminum oxide coated sample, but not on the untreated sample. In addition to that a small amount (50 ppm) of magnesium ions can enhance osteogenic differentiation as reported previously, our present data show a low concentration of hydrogen can give rise to the same effect. To compare the bone volume change between the plasma-treated magnesium implant and untreated control, micro-computed tomography is performed and the plasma-treated implant is found to induce significant new bone formation adjacent to the implant from day 1 until the end of the animal study. On the contrary, bone loss is observed during the first week post-operation from the untreated magnesium sample. Owing to the protection offered by the Al2O3 layer, the plasma-treated implant degrades more slowly and the small amount of released magnesium ions stimulate new bone formation locally as revealed by histological analyses. Scanning electron microscopy discloses that the Al2O3 layer at the bone-implant interface is still present two months after implantation. In addition, no inflammation or tissue necrosis is observed from both treated and untreated implants. These promising results suggest that the plasma-treated magnesium implant can stimulate bone formation in vivo in a minimal invasive way and without causing post-operative complications. PMID:24060425

  5. Causality between expansion of seismic cloud and maximum magnitude of induced seismicity in geothermal field

    NASA Astrophysics Data System (ADS)

    Mukuhira, Yusuke; Asanuma, Hiroshi; Ito, Takatoshi; Häring, Markus

    2016-04-01

    Occurrence of induced seismicity with large magnitude is critical environmental issues associated with fluid injection for shale gas/oil extraction, waste water disposal, carbon capture and storage, and engineered geothermal systems (EGS). Studies for prediction of the hazardous seismicity and risk assessment of induced seismicity has been activated recently. Many of these studies are based on the seismological statistics and these models use the information of the occurrence time and event magnitude. We have originally developed physics based model named "possible seismic moment model" to evaluate seismic activity and assess seismic moment which can be ready to release. This model is totally based on microseismic information of occurrence time, hypocenter location and magnitude (seismic moment). This model assumes existence of representative parameter having physical meaning that release-able seismic moment per rock volume (seismic moment density) at given field. Seismic moment density is to be estimated from microseismic distribution and their seismic moment. In addition to this, stimulated rock volume is also inferred by progress of microseismic cloud at given time and this quantity can be interpreted as the rock volume which can release seismic energy due to weakening effect of normal stress by injected fluid. Product of these two parameters (equation (1)) provide possible seismic moment which can be released from current stimulated zone as a model output. Difference between output of this model and observed cumulative seismic moment corresponds the seismic moment which will be released in future, based on current stimulation conditions. This value can be translated into possible maximum magnitude of induced seismicity in future. As this way, possible seismic moment can be used to have feedback to hydraulic stimulation operation in real time as an index which can be interpreted easily and intuitively. Possible seismic moment is defined as equation (1), where D

  6. Nanostructured Surfaces of Dental Implants

    PubMed Central

    Bressan, Eriberto; Sbricoli, Luca; Guazzo, Riccardo; Tocco, Ilaria; Roman, Marco; Vindigni, Vincenzo; Stellini, Edoardo; Gardin, Chiara; Ferroni, Letizia; Sivolella, Stefano; Zavan, Barbara

    2013-01-01

    The structural and functional fusion of the surface of the dental implant with the surrounding bone (osseointegration) is crucial for the short and long term outcome of the device. In recent years, the enhancement of bone formation at the bone-implant interface has been achieved through the modulation of osteoblasts adhesion and spreading, induced by structural modifications of the implant surface, particularly at the nanoscale level. In this context, traditional chemical and physical processes find new applications to achieve the best dental implant technology. This review provides an overview of the most common manufacture techniques and the related cells-surface interactions and modulation. A Medline and a hand search were conducted to identify studies concerning nanostructuration of implant surface and their related biological interaction. In this paper, we stressed the importance of the modifications on dental implant surfaces at the nanometric level. Nowadays, there is still little evidence of the long-term benefits of nanofeatures, as the promising results achieved in vitro and in animals have still to be confirmed in humans. However, the increasing interest in nanotechnology is undoubted and more research is going to be published in the coming years. PMID:23344062

  7. Auditory midbrain implant: a review.

    PubMed

    Lim, Hubert H; Lenarz, Minoo; Lenarz, Thomas

    2009-09-01

    The auditory midbrain implant (AMI) is a new hearing prosthesis designed for stimulation of the inferior colliculus in deaf patients who cannot sufficiently benefit from cochlear implants. The authors have begun clinical trials in which five patients have been implanted with a single shank AMI array (20 electrodes). The goal of this review is to summarize the development and research that has led to the translation of the AMI from a concept into the first patients. This study presents the rationale and design concept for the AMI as well a summary of the animal safety and feasibility studies that were required for clinical approval. The authors also present the initial surgical, psychophysical, and speech results from the first three implanted patients. Overall, the results have been encouraging in terms of the safety and functionality of the implant. All patients obtain improvements in hearing capabilities on a daily basis. However, performance varies dramatically across patients depending on the implant location within the midbrain with the best performer still not able to achieve open set speech perception without lip-reading cues. Stimulation of the auditory midbrain provides a wide range of level, spectral, and temporal cues, all of which are important for speech understanding, but they do not appear to sufficiently fuse together to enable open set speech perception with the currently used stimulation strategies. Finally, several issues and hypotheses for why current patients obtain limited speech perception along with several feasible solutions for improving AMI implementation are presented. PMID:19762428

  8. Therapy using implanted organic bioelectronics

    PubMed Central

    Jonsson, Amanda; Song, Zhiyang; Nilsson, David; Meyerson, Björn A.; Simon, Daniel T.; Linderoth, Bengt; Berggren, Magnus

    2015-01-01

    Many drugs provide their therapeutic action only at specific sites in the body, but are administered in ways that cause the drug’s spread throughout the organism. This can lead to serious side effects. Local delivery from an implanted device may avoid these issues, especially if the delivery rate can be tuned according to the need of the patient. We turned to electronically and ionically conducting polymers to design a device that could be implanted and used for local electrically controlled delivery of therapeutics. The conducting polymers in our device allow electronic pulses to be transduced into biological signals, in the form of ionic and molecular fluxes, which provide a way of interfacing biology with electronics. Devices based on conducting polymers and polyelectrolytes have been demonstrated in controlled substance delivery to neural tissue, biosensing, and neural recording and stimulation. While providing proof of principle of bioelectronic integration, such demonstrations have been performed in vitro or in anesthetized animals. Here, we demonstrate the efficacy of an implantable organic electronic delivery device for the treatment of neuropathic pain in an animal model. Devices were implanted onto the spinal cord of rats, and 2 days after implantation, local delivery of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) was initiated. Highly localized delivery resulted in a significant decrease in pain response with low dosage and no observable side effects. This demonstration of organic bioelectronics-based therapy in awake animals illustrates a viable alternative to existing pain treatments, paving the way for future implantable bioelectronic therapeutics. PMID:26601181

  9. Auditory Midbrain Implant: A Review

    PubMed Central

    Lim, Hubert H.; Lenarz, Minoo; Lenarz, Thomas

    2009-01-01

    The auditory midbrain implant (AMI) is a new hearing prosthesis designed for stimulation of the inferior colliculus in deaf patients who cannot sufficiently benefit from cochlear implants. The authors have begun clinical trials in which five patients have been implanted with a single shank AMI array (20 electrodes). The goal of this review is to summarize the development and research that has led to the translation of the AMI from a concept into the first patients. This study presents the rationale and design concept for the AMI as well a summary of the animal safety and feasibility studies that were required for clinical approval. The authors also present the initial surgical, psychophysical, and speech results from the first three implanted patients. Overall, the results have been encouraging in terms of the safety and functionality of the implant. All patients obtain improvements in hearing capabilities on a daily basis. However, performance varies dramatically across patients depending on the implant location within the midbrain with the best performer still not able to achieve open set speech perception without lip-reading cues. Stimulation of the auditory midbrain provides a wide range of level, spectral, and temporal cues, all of which are important for speech understanding, but they do not appear to sufficiently fuse together to enable open set speech perception with the currently used stimulation strategies. Finally, several issues and hypotheses for why current patients obtain limited speech perception along with several feasible solutions for improving AMI implementation are presented. PMID:19762428

  10. [Revision surgery after implantation of a vertebral disc prosthesis].

    PubMed

    Hopf, C

    2008-04-01

    Assessment of the revisability of surgery after the endoprosthetic replacement of vertebral discs shows that the surgical approach depends on the time of revision surgery and the reason why it is carried out. Our experience is based on nine revision operations out of 152 cervical vertebra prostheses of the Bryan and Prodisc C types implanted from 2003 to 2007 and 312 endoprostheses of the Charité and Prodisc types implanted from 1999 to 2007. Our own results show differing approaches in perioperative or late postoperative revision operations. Operations to exchange implants were not possible, whereas a change of surgical procedure is the rule. The same access route can usually be selected in the cervical spine, but in the lumbar spine this can only be done perioperatively; if revision surgery is carried out at a later date, an alternative access route must be used. Using strict indications for the primary implant is the only way to prevent postoperative revision surgery that is due to an inaccurate primary assessment and not to the vertebral endoprosthesis (e.g. post-discotomy syndrome, facet joint arthropathy, rotation instability, vertebral slip). The next generation of vertebral disc endoprostheses must incorporate reduced load of the zygapophyseal joints and improved revisability. PMID:18340432

  11. Why are mini-implants lost: The value of the implantation technique!

    PubMed Central

    Romano, Fabio Lourenço; Consolaro, Alberto

    2015-01-01

    The use of mini-implants have made a major contribution to orthodontic treatment. Demand has aroused scientific curiosity about implant placement procedures and techniques. However, the reasons for instability have not yet been made totally clear. The aim of this article is to establish a relationship between implant placement technique and mini-implant success rates by means of examining the following hypotheses: 1) Sites of poor alveolar bone and little space between roots lead to inadequate implant placement; 2) Different sites require mini-implants of different sizes! Implant size should respect alveolar bone diameter; 3) Properly determining mini-implant placement site provides ease for implant placement and contributes to stability; 4) The more precise the lancing procedures, the better the implant placement technique; 5) Self-drilling does not mean higher pressures; 6) Knowing where implant placement should end decreases the risk of complications and mini-implant loss. PMID:25741821

  12. Imaging of common breast implants and implant-related complications: A pictorial essay

    PubMed Central

    Shah, Amisha T; Jankharia, Bijal B

    2016-01-01

    The number of women undergoing breast implant procedures is increasing exponentially. It is, therefore, imperative for a radiologist to be familiar with the normal and abnormal imaging appearances of common breast implants. Diagnostic imaging studies such as mammography, ultrasonography, and magnetic resonance imaging are used to evaluate implant integrity, detect abnormalities of the implant and its surrounding capsule, and detect breast conditions unrelated to implants. Magnetic resonance imaging of silicone breast implants, with its high sensitivity and specificity for detecting implant rupture, is the most reliable modality to asses implant integrity. Whichever imaging modality is used, the overall aim of imaging breast implants is to provide the pertinent information about implant integrity, detect implant failures, and to detect breast conditions unrelated to the implants, such as cancer. PMID:27413269

  13. Trends in flood peaks' magnitude and seasonality in European transects

    NASA Astrophysics Data System (ADS)

    Diamantini, Elena; Mallucci, Stefano; Allamano, Paola; Claps, Pierluigi; Laio, Francesco; Viglione, Alberto; Hall, Julia; Blöschl, Günter

    2015-04-01

    In the last decade floods seems to have lashed more and more European population, so that more accurate studies concerning flood events tendencies are needed. We present a work in which trends in flood peaks' magnitude and seasonality (in time and space) are analyzed at the European scale: in total 2055 and 4340 stations respectively for magnitude and seasonality are considered along transect lines including entire nations, ranging typically from north to south of Europe. The work is part of the ERC Project "Deciphering River Flood Change". Trend analysis of flood magnitudes is applied to time series longer than 40 years. We find that there is a cluster of stations with negative trends in flood magnitude around the alpine and perialpine area. Positive trends are more frequent in the valleys of the mid Europe. We also use quantile regressions to investigate the behaviour of the highest quantiles, corresponding to floods with the highest return period. The original database is further divided into four classes based on station elevation; the group of catchments between 500 and 1000 m a.s.l. has the most positive trends for the large quantiles. The analysis is further developed by considering the coefficient of variation in 10-years time windows covering the data; the possible presence of trends in the CV is investigated. The obtained results show that there is a global prevalence of positive trend in the CVs, in particular for stations between 500 and 1000 m a.s.l., demonstrating a tendency toward the increase of very large (and possibly very small) annual maxima. To better discriminate the above results we used quantile regressions, able to highlight the trend behaviour of the highest quantiles computed on flood time series, Moreover, the database is divided into four classes based on station elevation. Results show that the group of catchments between 500 and 1000 m a.s.l. has definite and positive trends for the large quantiles. A different branch of this study

  14. Implantable Radio Frequency Identification Sensors: Wireless Power and Communication

    PubMed Central

    Hutchens, Chriswell; Rennaker, Robert L.; Venkataraman, Srinivasan; Ahmed, Rehan; Liao, Ran; Ibrahim, Tamer

    2013-01-01

    There are significant technical challenges in the development of a fully implantable wirelessly powered neural interface. Challenges include wireless transmission of sufficient power to the implanted device to ensure reliable operation for decades without replacement, minimizing tissue heating, and adequate reliable communications bandwidth. Overcoming these challenges is essential for the development of implantable closed loop system for the treatment of disorders ranging from epilepsy, incontinence, stroke and spinal cord injury. We discuss the development of the wireless power, communication and control for a Radio-Frequency Identification Sensor (RFIDS) system with targeted power range for a 700mV, 30 to 40uA load attained at −2dBm. PMID:22254944

  15. Implantable radio frequency identification sensors: wireless power and communication.

    PubMed

    Hutchens, Chriswell; Rennaker, Robert L; Venkataraman, Srinivasan; Ahmed, Rehan; Liao, Ran; Ibrahim, Tamer

    2011-01-01

    There are significant technical challenges in the development of a fully implantable wirelessly powered neural interface. Challenges include wireless transmission of sufficient power to the implanted device to ensure reliable operation for decades without replacement, minimizing tissue heating, and adequate reliable communications bandwidth. Overcoming these challenges is essential for the development of implantable closed loop system for the treatment of disorders ranging from epilepsy, incontinence, stroke and spinal cord injury. We discuss the development of the wireless power, communication and control for a Radio-Frequency Identification Sensor (RFIDS) system with targeted power range for a 700 mV, 30 to 40 uA load attained at -2 dBm. PMID:22254944

  16. Perceval S aortic valve implantation in an achondroplastic Dwarf

    PubMed Central

    Baikoussis, Nikolaos G.; Argiriou, Michalis; Argiriou, Orestis; Dedeilias, Panagiotis

    2016-01-01

    Despite cardiovascular disease in patients with dwarfism is not rare; there is a lack of reports referring to cardiac interventions in such patients. Dwarfism may be due to achondroplasia or hormonal growth disorders. We present a 58-year-old woman with episodes of dyspnea for several months. She underwent on transthoracic echocardiography, and she diagnosed with severe aortic valve stenosis. She referred to our department for surgical treatment of this finding. In accordance of her anthropometric characteristics and her very small aortic annulus, we had the dilemma of prosthesis selection. We decided to implant a stentless valve to optimize her effective orifice area. Our aim is to present the successful Perceval S valve implantation and the descriptions of the problems coming across in operating on these special patients. To our knowledge, this is the first case patient in which a Perceval S valve is implanted according to the international bibliography. PMID:26750695

  17. Cardiac Implantable Electronic Device Infection in Patients at Risk

    PubMed Central

    Tarakji, Khaldoun G; Ellis, Christopher R; Defaye, Pascal; Kennergren, Charles

    2016-01-01

    The incidence of infection following implantation of cardiac implantable electronic devices (CIEDs) is increasing at a faster rate than that of device implantation. Patients with a CIED infection usually require hospitalisation and complete device and lead removal. A significant proportion die from their infection. Transvenous lead extraction (TLE) is associated with rare but serious complications including major vascular injury or cardiac perforation. Operator experience and advances in lead extraction methods, including laser technology and rotational sheaths, have resulted in procedures having a low risk of complication and mortality. Strategies for preventing CIED infections include intravenous antibiotics and aseptic surgical techniques. An additional method to reduce CIED infection may be the use of antibacterial TYRX™ envelope. Data from non-randomised cohort studies have indicated that antibacterial envelope use can reduce the incidence of CIED infection by more than 80 % in high-risk patients and a randomised clinical trial is ongoing. PMID:27403296

  18. Surgical implantation and biocompatibility of central nervous system auditory prostheses.

    PubMed

    Niparko, J K; Altschuler, R A; Xue, X L; Wiler, J A; Anderson, D J

    1989-12-01

    As part of a program to determine the feasibility of a CNS auditory prosthesis, the tissue reaction to electrodes chronically implanted in the cochlear nucleus (CN) of the guinea pig was examined. Varied open operative approaches and microelectrode designs were utilized. Silicon substrate thin film and platinum-iridium wire electrodes, tethered and untethered, were placed successfully in different divisions of the CN. Implantation through a posterior suboccipital approach was most successful. Histologic examinations demonstrated a glial cell proliferation confined to the area of the electrode track that never exceeded 15 microns in width. No neuronal loss or significant effect on cell morphology was seen, and reactive cells were absent. Electrode migration was apparent in a minority of animal preparations. Although potential problems were identified, our findings lend support to the feasibility of implanting a neuroprosthesis in the CN and have helped to establish methods for future studies of chronic intranuclear stimulation. PMID:2589766

  19. Perceval S aortic valve implantation in an achondroplastic Dwarf.

    PubMed

    Baikoussis, Nikolaos G; Argiriou, Michalis; Argiriou, Orestis; Dedeilias, Panagiotis

    2016-01-01

    Despite cardiovascular disease in patients with dwarfism is not rare; there is a lack of reports referring to cardiac interventions in such patients. Dwarfism may be due to achondroplasia or hormonal growth disorders. We present a 58-year-old woman with episodes of dyspnea for several months. She underwent on transthoracic echocardiography, and she diagnosed with severe aortic valve stenosis. She referred to our department for surgical treatment of this finding. In accordance of her anthropometric characteristics and her very small aortic annulus, we had the dilemma of prosthesis selection. We decided to implant a stentless valve to optimize her effective orifice area. Our aim is to present the successful Perceval S valve implantation and the descriptions of the problems coming across in operating on these special patients. To our knowledge, this is the first case patient in which a Perceval S valve is implanted according to the international bibliography. PMID:26750695

  20. Understanding high magnitude flood risk: evidence from the past

    NASA Astrophysics Data System (ADS)

    MacDonald, N.

    2009-04-01

    The average length of gauged river flow records in the UK is ~25 years, which presents a problem in determining flood risk for high-magnitude flood events. Severe floods have been recorded in many UK catchments during the past 10 years, increasing the uncertainty in conventional flood risk estimates based on river flow records. Current uncertainty in flood risk has implications for society (insurance costs), individuals (personal vulnerability) and water resource managers (flood/drought risk). An alternative approach is required which can improve current understanding of the flood frequency/magnitude relationship. Historical documentary accounts are now recognised as a valuable resource when considering the flood frequency/magnitude relationship, but little consideration has been given to the temporal and spatial distribution of these records. Building on previous research based on British rivers (urban centre): Ouse (York), Trent (Nottingham), Tay (Perth), Severn (Shrewsbury), Dee (Chester), Great Ouse (Cambridge), Sussex Ouse (Lewes), Thames (Oxford), Tweed (Kelso) and Tyne (Hexham), this work considers the spatial and temporal distribution of historical flooding. The selected sites provide a network covering many of the largest river catchments in Britain, based on urban centres with long detailed documentary flood histories. The chronologies offer an opportunity to assess long-term patterns of flooding, indirectly determining periods of climatic variability and potentially increased geomorphic activity. This research represents the first coherent large scale analysis undertaken of historical multi-catchment flood chronologies, providing an unparalleled network of sites, permitting analysis of the spatial and temporal distribution of historical flood patterns on a national scale.