Follow-Up of 6 Patients with Permanent ; Vena Cava Filters in the Prevention of Pulmonary Embolism

Directory of Open Access Journals (Sweden)

M. Vahedian

2011-10-01

Full Text Available Introduction & Objective: Venous thromboembolic disease is a significant cause of morbidity and mortality in the United States. Deep venous thrombosis (DVT and pulmonary embolism (PE are a spectrum of a single disease entity. In most clinical situations, anticoagulation is the preferred form of therapy .IVC filter placement when using anticoagulation therapy is contraindicated or proves ineffective. The placement of an IVC filter is considered standard preventive treatment for PE. The aim of this study was follow up of patients with permanent vena cava filters in the prevention of pulmonary embolism after six months. Materials & Methods: In this cross sectional study 6 patients with IVC filter were followed up after 6 months. They were examined about having emboli, reccurent DVT, edema, varicosis, bleeding, misplacement, and fracture of filter. Data were analyzed with SPSSV17. Results: 6 patients having a mean age of 58.6 years were evaluated. There was no difference in sex . The reason of admission in all cases was DVT. Doppler sonography was done for all the patients. In 66.66% anticoagulation therapy was done before surgery. The filter was placed percutaneously in all cases. After 6 months in 5 cases there were no signs of DVT, PE, edema, and varicosis. In addition one patient died because of respiratory arrest due to encephalopathy. No complications were seen during admission period. Conclusion: Although IVC filter increases the risk of recurrent DVT in the long term ,it remarkablely decreases the risk of PE.IVC filter is a useful and effective treatment in patients with contraindication of using anticoagulation therapy especially in patients with cancer. (Sci J Hamadan Univ Med Sci 2011;18(2:29-32

Perforation of the IVC: Rule Rather Than Exception After Longer Indwelling Times for the Günther Tulip and Celect Retrievable Filters

International Nuclear Information System (INIS)

Durack, Jeremy C.; Westphalen, Antonio C.; Kekulawela, Stephanie; Bhanu, Shiv B.; Avrin, David E.; Gordon, Roy L.; Kerlan, Robert K.

2012-01-01

Purpose: This study was designed to assess the incidence, magnitude, and impact upon retrievability of vena caval perforation by Günther Tulip and Celect conical inferior vena cava (IVC) filters on computed tomographic (CT) imaging. Methods: Günther Tulip and Celect IVC filters placed between July 2007 and May 2009 were identified from medical records. Of 272 IVC filters placed, 50 (23 Günther Tulip, 46%; 27 Celect, 54%) were retrospectively assessed on follow-up abdominal CT scans performed for reasons unrelated to the filter. Computed tomography scans were examined for evidence of filter perforation through the vena caval wall, tilt, or pericaval tissue injury. Procedure records were reviewed to determine whether IVC filter retrieval was attempted and successful. Results: Perforation of at least one filter component through the IVC was observed in 43 of 50 (86%) filters on CT scans obtained between 1 and 880 days after filter placement. All filters imaged after 71 days showed some degree of vena caval perforation, often as a progressive process. Filter tilt was seen in 20 of 50 (40%) filters, and all tilted filters also demonstrated vena caval perforation. Transjugular removal was attempted in 12 of 50 (24%) filters and was successful in 11 of 12 (92%). Conclusions: Longer indwelling times usually result in vena caval perforation by retrievable Günther Tulip and Celect IVC filters. Although infrequently reported in the literature, clinical sequelae from IVC filter components breaching the vena cava can be significant. We advocate filter retrieval as early as clinically indicated and increased attention to the appearance of IVC filters on all follow-up imaging studies.

Impact of Anticoagulation in Elderly Patients With Pulmonary Embolism That Undergo IVC Filter Placement: A Retrospective Cohort Study.

Science.gov (United States)

Falatko, John M; Dalal, Bhavinkumar; Qu, Lihua

2017-12-01

Anticoagulation is the primary treatment for pulmonary embolism (PE). Inferior vena cava (IVC) filters are an adjunctive intervention to prevent recurrent pulmonary embolism. Long-term outcomes in elderly patients with contraindications to anticoagulation after IVC filter placement for prevention of recurrent pulmonary embolism have yet to be assessed. Patients ≥60years of age, that had an IVC filter placed between 1 January, 2008 and 2 February, 2013, with a primary diagnosis of pulmonary embolism, were included. Patients that died during index hospitalisation, were discharged to hospice, or had active malignancy were excluded. The primary endpoint was overall survival. Patients were divided depending on whether they were treated with an approved anticoagulant for VTE or had no anticoagulant. Of the 152 patients identified, 55 were not anti-coagulated after IVC filter placement. The incidence of death was 0.4 per 1000 filter days and 0.7 per 1000 filter days in the anti-coagulated and untreated groups respectively (p-value=0.06). After statistical correction for co-morbid conditions, the effect of anticoagulation was not significant (HR 0.82 CI 0.49-1.37, p-value 0.46). Age was a significant confounder that was associated with death. Increased BMI was protective. Indications for IVC filter placement were numerous, but similar between the two groups. Treatment with an approved anticoagulant is recommended after IVC filter placement for prevention of recurrent PE, however its effect may be attenuated by advanced age. In elderly patients that have undergone IVC filter placement for prevention of recurrent PE, survival may be more dependent on age and co-morbid conditions than exposure to anticoagulation. Copyright © 2017 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

IVC filter placements in children: nationwide comparison of practice patterns at adult and children's hospitals using the Kids' Inpatient Database.

Science.gov (United States)

Wadhwa, Vibhor; Trivedi, Premal S; Ali, Sumera; Ryu, Robert K; Pezeshkmehr, Amir

2018-02-01

Inferior vena cava (IVC) filter placement in children has been described in literature, but there is variability with regard to their indications. No nationally representative study has been done to compare practice patterns of filter placements at adult and children's hospitals. To perform a nationally representative comparison of IVC filter placement practices in children at adult and children's hospitals. The 2012 Kids' Inpatient Database was searched for IVC filter placements in children filter insertion (38.7), IVC filter placements were identified. A small number of children with congenital cardiovascular anomalies codes were excluded to improve specificity of the code used to identify filter placement. Filter placements were further classified by patient demographics, hospital type (children's and adult), United States geographic region, urban/rural location, and teaching status. Statistical significance of differences between children's or adult hospitals was determined using the Wilcoxon rank sum test. A total of 618 IVC filter placements were identified in children filters were placed in the setting of venous thromboembolism in children's hospitals (40/44, 90%) compared to adult hospitals (246/573, 43%) (Pfilters comprised 327/573 (57%) at adult hospitals, with trauma being the most common indication (301/327, 92%). The mean length of stay for patients receiving filters was 24.5 days in children's hospitals and 18.4 days in adult hospitals. The majority of IVC filters in children are placed in adult hospital settings. Children's hospitals are more likely to place therapeutic filters for venous thromboembolism, compared to adult hospitals where the prophylactic setting of trauma predominates.

Role of IVC Filters in Endovenous Therapy for Deep Venous Thrombosis: The FILTER-PEVI (Filter Implantation to Lower Thromboembolic Risk in Percutaneous Endovenous Intervention) Trial

International Nuclear Information System (INIS)

Sharifi, Mohsen; Bay, Curt; Skrocki, Laura; Lawson, David; Mazdeh, Shahnaz

2012-01-01

Objectives: The purpose of this study was to evaluate the necessity of and recommend indications for inferior vena cava (IVC) filter implantation during percutaneous endovenous intervention (PEVI) for deep venous thrombosis (DVT).BackgroundPEVI has emerged as a powerful tool in the management of acute proximal DVT. Instrumentation of extensive fresh thrombus is potentially associated with iatrogenic pulmonary embolism (PE). The true frequency of this complication has not been studied in a randomized fashion. We evaluated IVC filter implantation during PEVI for DVT. Methods: A total of 141 patients with symptomatic proximal DVT undergoing PEVI for symptomatic DVT were randomized to receive an IVC filter (70 patients) or no filter (71 patients; control group). The anticoagulation and PEVI regimen were similar between the two groups. Patients with development of symptoms suggestive of PE underwent objective testing for PE. Results: PE developed in 1 of the 14 symptomatic patients in the filter group and 8 of the 22 patients in the control group (P = 0.048). There was no mortality in any group. Three patients (4.2%) in the control group had transient hemodynamic instability necessitating resuscitory efforts. Predictors of iatrogenic PE were found to be PE at admission; involvement of two or more adjacent venous segments with acute thrombus; inflammatory form of DVT (severe erythema, edema, pain, and induration); and vein diameter of ≥7 mm with preserved architecture. Conclusions: IVC filter implantation during PEVI reduces the risk of iatrogenic PE by eightfold without a mortality benefit. A selective approach may be exercised in filter implantation during PEVI.

Role of IVC Filters in Endovenous Therapy for Deep Venous Thrombosis: The FILTER-PEVI (Filter Implantation to Lower Thromboembolic Risk in Percutaneous Endovenous Intervention) Trial

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Sharifi, Mohsen, E-mail: seyedmohsensharifi@yahoo.com [Arizona Cardiovascular Consultants (United States); Bay, Curt [A.T. Still University, Arizona School of Health Sciences (United States); Skrocki, Laura; Lawson, David; Mazdeh, Shahnaz [Arizona Cardiovascular Consultants (United States)

2012-12-15

Objectives: The purpose of this study was to evaluate the necessity of and recommend indications for inferior vena cava (IVC) filter implantation during percutaneous endovenous intervention (PEVI) for deep venous thrombosis (DVT).BackgroundPEVI has emerged as a powerful tool in the management of acute proximal DVT. Instrumentation of extensive fresh thrombus is potentially associated with iatrogenic pulmonary embolism (PE). The true frequency of this complication has not been studied in a randomized fashion. We evaluated IVC filter implantation during PEVI for DVT. Methods: A total of 141 patients with symptomatic proximal DVT undergoing PEVI for symptomatic DVT were randomized to receive an IVC filter (70 patients) or no filter (71 patients; control group). The anticoagulation and PEVI regimen were similar between the two groups. Patients with development of symptoms suggestive of PE underwent objective testing for PE. Results: PE developed in 1 of the 14 symptomatic patients in the filter group and 8 of the 22 patients in the control group (P = 0.048). There was no mortality in any group. Three patients (4.2%) in the control group had transient hemodynamic instability necessitating resuscitory efforts. Predictors of iatrogenic PE were found to be PE at admission; involvement of two or more adjacent venous segments with acute thrombus; inflammatory form of DVT (severe erythema, edema, pain, and induration); and vein diameter of {>=}7 mm with preserved architecture. Conclusions: IVC filter implantation during PEVI reduces the risk of iatrogenic PE by eightfold without a mortality benefit. A selective approach may be exercised in filter implantation during PEVI.

Evidence-Based Evaluation of Inferior Vena Cava Filter Complications Based on Filter Type

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Deso, Steven E.; Idakoji, Ibrahim A.; Kuo, William T.

2016-01-01

Many inferior vena cava (IVC) filter types, along with their specific risks and complications, are not recognized. The purpose of this study was to evaluate the various FDA-approved IVC filter types to determine device-specific risks, as a way to help identify patients who may benefit from ongoing follow-up versus prompt filter retrieval. An evidence-based electronic search (FDA Premarket Notification, MEDLINE, FDA MAUDE) was performed to identify all IVC filter types and device-specific complications from 1980 to 2014. Twenty-three IVC filter types (14 retrievable, 9 permanent) were identified. The devices were categorized as follows: conical (n = 14), conical with umbrella (n = 1), conical with cylindrical element (n = 2), biconical with cylindrical element (n = 2), helical (n = 1), spiral (n = 1), and complex (n = 1). Purely conical filters were associated with the highest reported risks of penetration (90–100%). Filters with cylindrical or umbrella elements were associated with the highest reported risk of IVC thrombosis (30–50%). Conical Bard filters were associated with the highest reported risks of fracture (40%). The various FDA-approved IVC filter types were evaluated for device-specific complications based on best current evidence. This information can be used to guide and optimize clinical management in patients with indwelling IVC filters. PMID:27247477

Audit of the use of IVC filters in the UK: experience from three centres over 12 years

Energy Technology Data Exchange (ETDEWEB)

Hammond, C.J. [Leeds General Infirmary, Leeds (United Kingdom)], E-mail: chris.hammond@doctors.org.uk; Bakshi, D.R. [Royal Liverpool University Hospital, Liverpool (United Kingdom); Currie, R.J. [Royal Devon and Exeter Hospital, Exeter (United Kingdom); Patel, J.V. [Leeds General Infirmary, Leeds (United Kingdom); Kinsella, D. [Royal Devon and Exeter Hospital, Exeter (United Kingdom); McWilliams, R.G. [Royal Liverpool University Hospital, Liverpool (United Kingdom); Watkinson, A. [Royal Devon and Exeter Hospital, Exeter (United Kingdom); Nicholson, A.A. [Leeds General Infirmary, Leeds (United Kingdom)

2009-05-15

Aim: To audit the use of inferior vena cava (IVC) filter insertions at three UK centres over 12 years to assess whether trends in filter use in the UK mirrored those seen elsewhere. Materials and methods: Radiology department databases were interrogated for IVC filter insertions and removals between 1994 and 2006. Reports for these interventions, along with prior and subsequent imaging reports, were analysed. Follow-up data were obtained when available. Results: Five hundred and sixteen filters were placed with a significant year-on-year trend towards increasing use. Fifty-seven percent of filters placed were for absolute indications and 37% for relative indications. The filters were used for prophylaxis in 6% of patients in the absence of proven pulmonary embolism (PE) or deep vein thrombosis (DVT). A retrievable filter was used in 74% of cases with retrieval attempted in 40% of these and no evidence of an increasing rate of retrieval over time. A significant complication related to insertion or retrieval was encountered in 0.4 and 1% of procedures, respectively. Mean 24 h and 30 day mortalities were 1 and 8%, respectively. There was an absence of organized follow-up at all three centres. Conclusion: IVC filter use in the UK is increasing. The use of retrievable filters has not resulted in increased filter retrieval. Filter insertion and retrieval is associated with a low risk of significant complication, but lack of systematic follow-up limits conclusions regarding safety and efficacy.

The clinical application of inferior vena cava filters: the essential point is to use it appropriately

International Nuclear Information System (INIS)

Yang Zhengqiang; Li Linsun

2011-01-01

This paper aims to describe the history and current situation of the clinical application of inferior venal cava (IVC) filters. As there is a possible tendency for physicians to abuse the IVC filters in clinical practice, the authors think that it is necessary now to judge the advantages and disadvantages of the use of IVC filters again and to conscientiously reconsider what kind of patients are suitable for IVC filter implantation. In this article, the proper characteristics that an ideal IVC filter should possess are introduced, the indications for IVC filter implantation are discussed and the complications occurred after IVC filter implantation are analyzed. The authors believe that the retrievable filters will gradually substitute for permanent filters, for this reason, studies concerning IVC retrievable filters will become the hot spots of research in the near future. (authors)

Vena cava filter behavior and endovascular response : An experimental in vivo study

NARCIS (Netherlands)

Hoekstra, A; Hoogeveen, Y; Elstrodt, JM; Tiebosch, ATMG

2003-01-01

Purpose: To evaluate the behavior and endovascular response of a new nitinol permanent vena cava filter, the TrapEase. Methods: Percutaneous implantation of the filter was performed in six goats, with inferior vena cava (IVC) diameter close to that of man. Radiologic data concerning the IVC, filter

Practice patterns of retrievable inferior vena cava filters and predictors of filter retrieval in patients with pulmonary embolism.

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Kang, Jieun; Ko, Heung-Kyu; Shin, Ji Hoon; Ko, Gi-Young; Jo, Kyung-Wook; Huh, Jin Won; Oh, Yeon-Mok; Lee, Sang-Do; Lee, Jae Seung

2017-12-01

Retrievable inferior vena cava (IVC) filters are increasingly used in patients with venous thromboembolism (VTE) who have contraindications to anticoagulant therapy. However, previous studies have shown that many retrievable filters are left permanently in patients. This study aimed to identify the common indications for IVC filter insertion, the filter retrieval rate, and the predictive factors for filter retrieval attempts. To this end, a retrospective cohort study was performed at a tertiary care center in South Korea between January 2010 and May 2016. Electronic medical charts were reviewed for patients with pulmonary embolism (PE) who underwent IVC filter insertion. A total of 439 cases were reviewed. The most common indication for filter insertion was a preoperative/procedural aim, followed by extensive iliofemoral deep vein thrombosis (DVT). Retrieval of the IVC filter was attempted in 44.9% of patients. The retrieval success rate was 93.9%. History of cerebral hemorrhage, malignancy, and admission to a nonsurgical department were the significant predictive factors of a lower retrieval attempt rate in multivariate analysis. With the increased use of IVC filters, more issues should be addressed before placing a filter and physicians should attempt to improve the filter retrieval rate.

Guenther Tulip Filter Retrieval from a Left-sided Inferior Vena Cava

International Nuclear Information System (INIS)

Brountzos, Elias N.; Kaufman, John A.; Lakin, Paul L.

2004-01-01

Optional (retrievable) inferior cava filters (IVC) may have advantages over permanent filters in a certain subset of patients, especially in view of recent concerns about the long-term thrombotic complications of the latter. Retrieval of the Guenther Tulip Filter (GTF), an optional filter, has been reported in a total of 76 patients. We present the first description of GTF retrieval from a left-sided IVC using the right internal jugular approach

Successful catheter directed thrombolysis of IVC and renal vein occlusive thrombus.

LENUS (Irish Health Repository)

McCarthy, E

2011-11-01

Thrombus formation is a recognised complication of IVC filter placement, however IVC and bilateral renal vein occlusion secondary to thrombus is much less common. We present a case of infrahepatic caval and bilateral renal vein occlusion secondary to thrombosis of a suprarenal IVC filter. With progressive clinical deterioration and failure of conservative medical management the patient underwent successful mechanical disruption and catheter directed thrombolysis.

Atrophic inferior vena cava is a marker of chronicity of intra-filter and inferior vena cava thrombosis: based on CT findings.

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Chen, Liang; Shi, Wanyin; Gu, Jianping; He, Xu; Lou, Wensheng

2018-04-11

A permanently indwelling filter in the inferior vena cava (IVC) may induce caval thrombosis, which could develop and evolve from an acute to a chronic phase. The differential diagnosis of acute and chronic thromboses determines the treatment strategy. The role of computed tomography (CT) in diagnosing acute and chronic intra-filter and IVC thromboses has not been well established. This retrospective study summarizes the CT signs that indicate acute and chronic phases of intra-filter and IVC thromboses. This study included eight patients who developed a lower-extremity deep venous thrombosis (DVT) and were treated with intracaval filter placement as an alternative to anticoagulation and thrombolysis. During the follow-up, all patients developed an intra-filter thrombosis in the IVC confirmed by CT and/or CT venography (CTV). Demographic and CT data of all patients during the follow-up period were collected for analysis. All patients had normal-appearing IVCs prior to filter placement, as shown on trans-femoral venography. Eight filters (five TrapEase, three OptEase) were placed in the eight IVCs, respectively. Subsequently, IVC-CT or CTV revealed acute intra-filter or IVC thrombosis in all eight patients, manifesting as an intracaval filling defect and thickened IVC wall. Filter protrusion and secondary caval atrophy seen on CT indicated a chronically occluded IVC. IVC thrombosis may result from filter placement. The chronicity of caval thrombotic occlusion is likely to be associated with filter protrusion and secondary IVC atrophy revealed on CT scans.

Indications, management, and complications of temporary inferior vena cava filters

International Nuclear Information System (INIS)

Linsenmaier, Ulrich; Rieger, Johannes; Schenk, Franz; Rock, Clemens; Mangel, Eugen; Pfeifer, Klaus Juergen

1998-01-01

Purpose: We describe the results of a preliminary prospective study using different recently developed temporary and retrievable inferior vena cava (IVC) filters.Methods: Fifty temporary IVC filters (Guenther, Guenther Tulip, Antheor) were inserted in 47 patients when the required period of protection against pulmonary embolism (PE) was estimated to be less than 2 weeks. The indications were documented deep vein thrombosis (DVT) and temporary contraindications for anticoagulation, a high risk for PE, and PE despite DVT prophylaxis.Results: Filters were removed 1-12 days after placement and nine (18%) had captured thrombi. Complications were one PE during and after removal of a filter, two minor filter migrations, and one IVC thrombosis.Conclusion: Temporary filters are effective in trapping clots and protecting against PE, and the complication rate does not exceed that of permanent filters. They are an alternative when protection from PE is required temporarily, and should be considered in patients with a normal life expectancy.

The Guenther temporary inferior vena cava filter for short-term protection against pulmonary embolism

International Nuclear Information System (INIS)

Vos, Louwerens D.; Tielbeek, Alexander V.; Bom, Ernst P.; Gooszen, Harm C.; Vroegindeweij, Dammis

1997-01-01

Purpose. To evaluate clinically the Guenther temporary inferior vena cava (IVC) filter. Methods. Eleven IVC filters were placed in 10 patients. Indications for filter placement were surgical pulmonary embolectomy in seven patients, pulmonary embolism in two patients, and free-floating iliofemoral thrombus in one patient. Eight filters were inserted from the right femoral approach, three filters from the left. Follow-up was by plain abdominal radiographs, cavography, and duplex ultrasound (US). Eight patients received systemic heparinization. Follow-up, during 4-60 months after filter removal was by clinical assessment, and imaging of the lungs was performed when pulmonary embolism (PE) was suspected. Patients received anticoagulation therapy for at least 6 months. Results. Ten filters were removed without complications 7-14 days (mean 10 days) after placement. One restless patient pulled the filter back into the common femoral vein, and a permanent filter was placed. In two patients a permanent filter was placed prior to removal. One patient developed sepsis, and one an infection at the insertion site. Clinically no recurrent PE developed with the filter in place or during removal. One patient had recurrent PE 7 months after filter removal. Conclusion. The Guenther temporary IVC filter can be safely placed for short-term protection against PE. The use of this filter is not appropriate in agitated or immunocompromised patients

The Optional VenaTech™ Convertible™ Vena Cava Filter: Experimental Study in Sheep

International Nuclear Information System (INIS)

Le Blanche, Alain F.; Ricco, Jean-Baptiste; Bonneau, Michel; Reynaud, Philippe

2012-01-01

Purpose: Retrieval of optional caval filters may be impaired by filter tilting, migration, fracture, or embedding in the IVC wall. The goal of this experimental study was to evaluate a new optional filter, convertible by unlocking and removing the filter head. Methods: Forty-nine Pre-Alp sheep (average weight, 55 kg) were anesthetized. IVC was catheterized via the right femoral vein (n = 46) or via the internal jugular vein (n = 3) with a 12.9-F sheath. VenaTech ™ Convertible ™ IVC filters were inserted as either permanent filters (n = 14) or as filters to be converted. Conversion was immediately after deployment (n = 19) or delayed after 1, 3, or 6 months (n = 20). Filter delivery, deployment, and conversion with measurement of migration and tilting were evaluated by cavography. Incorporation of the filter’s stabilizers and arms in the IVC wall was assessed by gross anatomy. Results: Delivery system insertion, filter release, and immediate conversion were successful in all cases. Delayed conversion was completed in all but one sheep, due to insufficient snare tension. Complimentary balloon-catheter inflation was required in 12 of 20 delayed conversions to achieve filter opening. In all 49 sheep, no thrombosis, migration, or significant tilting occurred. Within 4 weeks of conversion, the filter’s stabilizers and arms were incorporated into the IVC wall. Upon removal, the filter head was free of intimal growth. Conclusions: The VenaTech ™ Convertible ™ optional IVC filter was successfully implanted in all sheep with no migration or tilting. Conversion at various dates by filter head removal was feasible in all but one case.

The Importance of Individual Ventilation Cottage (IVC) System

International Nuclear Information System (INIS)

Anee Suryani Sued; Fazliana Mohd Saaya; Mohd Ramli Ibrahim; Shafii Khamis

2015-01-01

Experimental animals such as rats and mice are used in scientific research, especially in research related to drugs, must be able to give the right decisions and authentic. The results are not accurate and authentic will harm humans, especially in pre-clinical studies of drugs (drug) trial. Therefore, the system of individual ventilated cages (IVC) has been developed in the Malaysian Nuclear Agency to ensure that animal experiments are always at the level of quality, healthy and disease free. IVC system was developed to replace conventional animal cage systems that have been used previously. The use of IVC systems in breed and maintain rats and mice to obtain disease-free animal, the animal known as SPF (Specific pathogen free animals). For this purpose, the IVC system using 'bedding' typical food and animal pests that have been purified to ensure that it meets the intended use of the system perfectly. In addition, system privileges are through the ventilation system that can isolate the one-way air enters and exits for each cage, and equipped with a HEPA filter (High -Efficiency-Particulate Air) filter which can prevent contamination of microorganisms for ventilation in the cage and the air in the vicinity , Through the use of IVC system, the quality and health of experimental animals that are bred and used in the Medical Technology Division can be improved and so can guarantee the accuracy and validity of the results of research conducted. (author)

An experimental and computational study of the inferior vena cava hemodynamics under respiratory-induced collapse of the infrarenal IVC.

Science.gov (United States)

Tedaldi, Elisabetta; Montanari, Chiara; Aycock, Kenneth I; Sturla, Francesco; Redaelli, Alberto; Manning, Keefe B

2018-04-01

Inferior vena cava (IVC) filters have been used for over five decades as an alternative to anticoagulation therapy in the treatment of venous thromboembolic disease. However, complications associated with IVC filters remain common. Though many studies have investigated blood flow in the IVC, the effects of respiration-induced IVC collapse have not been evaluated. Our hypothesis is that IVC collapse may have an influence on IVC filter performance. Therefore, we herein investigate the hemodynamics in uncollapsed and collapsed IVC configurations using in vitro flow experiments and computational simulations. Particle image velocimetry (PIV) is used to measure the hemodynamics in an idealized, compliant model of the human IVC made of silicone rubber. Flow is studied under uncollapsed and collapsed scenarios, with the minor diameter of the IVC reduced by 30% in the collapsed state. Both rest and exercise flow conditions are investigated, corresponding to suprarenal flow rates of 2 lpm and 5.5 lpm, respectively. Finite element analysis simulations are carried out in a computational model of the undeformed, idealized IVC to reproduce the 30% collapse configuration and an additional 50% collapse configuration. Computational fluid dynamics (CFD) simulations are then performed to predict the flow in the uncollapsed and collapsed scenarios, and CFD results are compared to the experimental data. The results show that the collapsed states generate a higher velocity jet at the iliac junction that propagates farther into the lumen of the vena cava in comparison to the jet generated in the uncollapsed state. Moreover, 50% collapse of the IVC causes a shift of the jet away from the IVC wall and towards the center of the vena cava lumen. The area of maximum wall shear stress occurs where the jet impacts the wall and is larger in the collapsed scenarios. Secondary flow is also more complex in the collapsed scenarios. Interestingly, this study demonstrates that a small variation in

Radiology-led Follow-up System for IVC Filters: Effects on Retrieval Rates and Times

International Nuclear Information System (INIS)

Lee, L.; Taylor, J.; Munneke, G.; Morgan, R.; Belli, A.-M.

2012-01-01

Purpose: Successful IVC filter retrieval rates fall with time. Serious complications have been reported following attempts to remove filters after 3–18 months. Failed retrieval may be associated with adverse clinical sequelae. This study explored whether retrieval rates are improved if interventional radiologists organize patient follow-up, rather than relying on the referring clinicians. Methods: Proactive follow-up of patients who undergo filter placement was implemented in May 2008. At the time of filter placement, a report was issued to the referring consultant notifying them of the advised timeframe for filter retrieval. Clinicians were contacted to arrange retrieval within 30 days. We compared this with our practice for the preceding year. Results: The numbers of filters inserted during the two time periods was similar, as were the numbers of retrieval attempts and the time scale at which they occurred. The rate of successful retrievals increased but not significantly. The major changes were better documentation of filter types and better clinical follow-up. After the change in practice, only one patient was lost to follow-up compared with six the preceding year. Conclusions: Although there was no significant improvement in retrieval rates, the proactive, radiology-led approach improved follow-up and documentation, ensuring that a clinical decision was made about how long the filter was required and whether retrieval should be attempted and ensuring that patients were not lost to follow-up.

Günther Tulip and Celect IVC filters in multiple-trauma patients.

Science.gov (United States)

Rosenthal, David; Kochupura, Paul V; Wellons, Eric D; Burkett, Allison B; Methodius-Rayford, Walaya C

2009-08-01

To evaluate results with the retrievable Günther Tulip (GT) and Celect inferior vena cava filters (IVCFs) placed at the intensive care unit (ICU) bedside under "real-time" intravascular ultrasound (IVUS) guidance in multiple-trauma patients. Between December 2004 and December 2008, 187 multiple-trauma patients (109 men; mean age 44+/-2 years, range 17-71) with contraindications to low-dose anticoagulation therapy or sequential compression devices had Günther Tulip (n = 97) or Celect (n = 90) retrievable IVCFs placed under real-time IVUS guidance. Günther Tulip filters were inserted using a "double-puncture" technique. The Celect IVCFs were placed with a simplified single-puncture technique in which the filter introducer sheath was advanced until the radiopaque tip "covered" the IVUS image of the renal vein, indicating that the filter sheath was in position for filter deployment. The 2 filter groups were compared on the endpoints of technical implantation success, retrievability, prevention of PE, and procedure-related deep vein thrombosis (DVT). As verified by abdominal radiography, 93.1% (174/187) of IVCFs were placed without complications; 6 IVCFs (all GT; p = 0.03 versus Celect) were misplaced in the iliac vein but uneventfully retrieved and replaced in the IVC within 24 hours. Two insertion site femoral vein DVTs (both in the dual puncture group; p>0.2) and 5 groin hematomas occurred during follow-up. GT filters were in place a mean of 107 days and Celect 97 days. In this time, 2 pulmonary embolisms occurred (1 in each group; p>0.2). Of the 115 filters scheduled for retrieval (50 Günther Tulip, 65 Celect), 33 (23 Günther Tulip, 10 Celect) could not be retrieved (p = 0.0004). Vena cavography identified filter tilting (>20 degrees ) in 21 cases (15 GT, 6 Celect), while 12 filters (8 GT, 4 Celect) had extended indwell times (mean 187 days) and excessive tissue ingrowth covering the retrieval hook. Subjectively, the Celect filters were clinically "easier" to

Gunther Tulip Retrievable Inferior Vena Caval Filters: Indications, Efficacy, Retrieval, and Complications

International Nuclear Information System (INIS)

Looby, S.; Given, M.F.; Geoghegan, T.; McErlean, A.; Lee, M.J.

2007-01-01

Purpose. We evaluated the Gunther Tulip (GT) retrievable inferior vena cava (IVC) filter with regard to indications, filtration efficacy, complications, retrieval window, and use of anticoagulation. Method. A retrospective study was performed of 147 patients (64 men, 83 women; mean age 58.8 years) who underwent retrievable GT filter insertion between 2001 and 2005. The indications for placement included a diagnosis of pulmonary embolism or deep venous thrombosis with a contraindication to anticoagulation (n = 68), pulmonary embolism or deep venous thrombosis while on anticoagulation (n = 49), prophylactic filter placement for high-risk surgical patients with a past history of pulmonary embolism or deep venous thrombosis (n = 20), and a high risk of pulmonary embolism or deep venous thrombosis (n = 10). Forty-nine of the 147 patients did not receive anticoagulation (33.7%) while 96 of 147 patients did, 82 of these receiving warfarin (56.5%), 11 receiving low-molecular weight heparins (7.58%), and 3 receiving antiplatelet agents alone (2.06%). Results. Filter placement was successful in 147 patients (100%). Two patients had two filters inserted. Of the 147 patients, filter deployment was on a permanent basis in 102 and with an intention to retrieve in 45 patients. There were 36 (80%) successful retrievals and 9 (20%) failed retrievals. The mean time to retrieval was 33.6 days. The reasons for failed retrieval included filter struts tightly adherent to the IVC wall (5/9), extreme filter tilt (2/9), and extensive filter thrombus (2/9). Complications included pneumothorax (n = 4), failure of filter expansion (n = 1), and breakthrough pulmonary embolism (n = 1). No IVC thrombotic episodes were recorded. Discussion. The Gunther Tulip retrievable filter can be used as a permanent or a retrievable filter. It is safe and efficacious. GT filters can be safely retrieved at a mean time interval of 33.6 days. The newly developed Celect filter may extend the retrieval interval

Impact of Physician Education and a Dedicated Inferior Vena Cava Filter Tracking System on Inferior Vena Cava Filter Use and Retrieval Rates Across a Large US Health Care Region.

Science.gov (United States)

Wang, Stephen L; Cha, Hsien-Hwa A; Lin, James R; Francis, Bolanos; Elizabeth, Wakley; Martin, Porras; Rajan, Sudhir

2016-05-01

To evaluate the effects of physician familiarity with current evidence and guidelines on inferior vena cava (IVC) filter use and the availability of IVC filter tracking infrastructure on retrieval rates. Fourteen continuing medical education-approved in-hospital grand rounds covering evidence-based review of the literature on IVC filter efficacy, patient-centered outcomes, guidelines for IVC filter indications, and complications were performed across a large United States (US) health care region serving more than 3.5 million members. A computer-based IVC filter tracking system was deployed simultaneously. IVC filter use, rates of attempted retrieval, and fulfillment of guidelines for IVC filter indications were retrospectively evaluated at each facility for 12 months before intervention (n = 427) and for 12 months after intervention (n = 347). After education, IVC filter use decreased 18.7%, with a member enrollment-adjusted decrease of 22.2%, despite an increasing IVC filter use trend for 4 years. Reduction in IVC filter use at each facility strongly correlated with physician attendance at grand rounds (r = -0.69; P = .007). Rates of attempted retrieval increased from 38.9% to 54.0% (P = .0006), with similar rates of successful retrieval (82.3% before education and 85.8% after education on first attempt). Improvement in IVC filter retrieval attempts correlated with physician attendance at grand rounds (r = 0.51; P = .051). IVC filter dwell times at first retrieval attempt were similar (10.2 wk before and 10.8 wk after). Physician education dramatically reduced IVC filter use across a large US health care region, and represents a learning opportunity for physicians who request and place them. Education and a novel tracking system improved rates of retrieval for IVC filter devices. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

Vena Cava Filter Retrieval with Aorto-Iliac Arterial Strut Penetration.

Science.gov (United States)

Holly, Brian P; Gaba, Ron C; Lessne, Mark L; Lewandowski, Robert J; Ryu, Robert K; Desai, Kush R; Sing, Ronald F

2018-05-03

To evaluate the safety and technical success of inferior vena cava (IVC) filter retrieval in the setting of aorto-iliac arterial strut penetration. IVC filter registries from six large United States IVC filter retrieval practices were retrospectively reviewed to identify patients who underwent IVC filter retrieval in the setting of filter strut penetration into the adjacent aorta or iliac artery. Patient demographics, implant duration, indication for placement, IVC filter type, retrieval technique and technical success, adverse events, and post procedural clinical outcomes were identified. Arterial penetration was determined based on pre-procedure CT imaging in all cases. The IVC filter retrieval technique used was at the discretion of the operating physician. Seventeen patients from six US centers who underwent retrieval of an IVC filter with at least one strut penetrating either the aorta or iliac artery were identified. Retrieval technical success rate was 100% (17/17), without any major adverse events. Post-retrieval follow-up ranging from 10 days to 2 years (mean 4.6 months) was available in 12/17 (71%) patients; no delayed adverse events were encountered. Findings from this series suggest that chronically indwelling IVC filters with aorto-iliac arterial strut penetration may be safely retrieved.

Percutaneous placement of bird's nest inferior vena cava filter

International Nuclear Information System (INIS)

Lee, Seung Hoon; Sung, Kyu Bo; Yoon, Hyun Ki

1999-01-01

To describe clinical experiences of the use of Bird's Nest inferior vena cava(IVC) filter. Between August 1991 and August 1997, IVC filter was percutaneously inserted in 51 patients with pulmonary embolism(PE) and deep vein thrombosis of the lower extremities. Indications for the placement of this filter were contraindication to anticoagulation in 17 patients, prophylaxis of PE in 17, failed anticoagulation in 11, massive PE with residual floating thrombus in three and complications involving anticoagulation in 3. In order to delineate the location of renal vein and extension of deep vein thrombosis into the IVC, all patients under went inferior vena cavography before filter placement. Thirty filters were inserted through the right femoral vein, 19 through the right internal jugular vein and three through the left femoral vein. The patients involved were followed up for periods ranging from one week to six years (mean 10 months). A Bird's Nest IVC filter was placed in the infrarenal IVC in 44 patients and in the suprarenal IVC in 7. Certain complicatioins ensued. IVC penetration occurred in three patients(5.9%), and in seven(1.37%) the filter wire prolapsed. Except for transient pain, however, there were no serious IVC penetration-related complications and no evidence of recurrence of PE in the cases involving prolapse of the filter wire. During follow up, clinically suspected recurrent PE was noted in two patients(3.9%), but there was no evidence of newly developed occlusion of the IVC. In patients who under went follow up, Bird's Nest IVC filter effectively prevented the development and recurrence of PE, and there were no complications. To prevent of penetration of the IVC and prolapse of the filter, however, technical skill was needed

Inferior Vena Cava Filter Placement and Retrieval Rates among Radiologists and Nonradiologists.

Science.gov (United States)

Guez, David; Hansberry, David R; Eschelman, David J; Gonsalves, Carin F; Parker, Laurence; Rao, Vijay M; Levin, David C

2018-04-01

To evaluate inferior vena cava (IVC) filter placement and retrieval rates among radiologists, vascular surgeons, cardiologists, other surgeons, and all other health care providers for Medicare fee-for-service beneficiaries in the years 2012-2015. The nationwide Medicare Physician/Supplier Procedure Summary Master Files were used to determine the volume and utilization rate of IVC filter placement, IVC filter repositioning, and IVC filter retrieval, which correspond to procedure codes 37191, 37192, and 37193, respectively. Procedural code 37193 was not available before 2012, so data were reviewed for the years 2012-2015. The total volume of Medicare IVC filter placement decreased from 57,785 in 2012 to 44,378 in 2015, with radiologists responsible for 60% of all filter placements. Volume of IVC filter placement declined across all specialties, including radiologists, who placed 33,744 in 2012 and 27,957 in 2015. In contrast, total retrieval of IVC filters increased from 4,060 removals in 2012 to 6,166 in 2015. Retrieval rate per 100,000 Medicare beneficiaries increased from 11 in 2012 to 16 in 2015. Radiologists removed the bulk of the filters: 64% in both 2012 and 2015. Vascular surgeons, cardiologists, and other surgeons retrieved, respectively, 20%, 10%, and 5% of all IVC filters in 2012 and 22%, 9%, and 5% in 2015. From 2012 to 2015, IVC filter placement steadily decreased across all specialties. Retrieval rate of IVC filters continued to rise over the same period. Radiologists were responsible for the majority of IVC filter placements and retrievals. Copyright © 2017 SIR. Published by Elsevier Inc. All rights reserved.

Prospective implementation of an algorithm for bedside intravascular ultrasound-guided filter placement in critically ill patients.

Science.gov (United States)

Killingsworth, Christopher D; Taylor, Steven M; Patterson, Mark A; Weinberg, Jordan A; McGwin, Gerald; Melton, Sherry M; Reiff, Donald A; Kerby, Jeffrey D; Rue, Loring W; Jordan, William D; Passman, Marc A

2010-05-01

Although contrast venography is the standard imaging method for inferior vena cava (IVC) filter insertion, intravascular ultrasound (IVUS) imaging is a safe and effective option that allows for bedside filter placement and is especially advantageous for immobilized critically ill patients by limiting resource use, risk of transportation, and cost. This study reviewed the effectiveness of a prospectively implemented algorithm for IVUS-guided IVC filter placement in this high-risk population. Current evidence-based guidelines were used to create a clinical decision algorithm for IVUS-guided IVC filter placement in critically ill patients. After a defined lead-in phase to allow dissemination of techniques, the algorithm was prospectively implemented on January 1, 2008. Data were collected for 1 year using accepted reporting standards and a quality assurance review performed based on intent-to-treat at 6, 12, and 18 months. As defined in the prospectively implemented algorithm, 109 patients met criteria for IVUS-directed bedside IVC filter placement. Technical feasibility was 98.1%. Only 2 patients had inadequate IVUS visualization for bedside filter placement and required subsequent placement in the endovascular suite. Technical success, defined as proper deployment in an infrarenal position, was achieved in 104 of the remaining 107 patients (97.2%). The filter was permanent in 21 (19.6%) and retrievable in 86 (80.3%). The single-puncture technique was used in 101 (94.4%), with additional dual access required in 6 (5.6%). Periprocedural complications were rare but included malpositioning requiring retrieval and repositioning in three patients, filter tilt >/=15 degrees in two, and arteriovenous fistula in one. The 30-day mortality rate for the bedside group was 5.5%, with no filter-related deaths. Successful placement of IVC filters using IVUS-guided imaging at the bedside in critically ill patients can be established through an evidence-based prospectively

Statewide Inferior Vena Cava Filter Placement, Complications, and Retrievals: Epidemiology and Recent Trends.

Science.gov (United States)

Charalel, Resmi A; Durack, Jeremy C; Mao, Jialin; Ross, Joseph S; Meltzer, Andrew J; Sedrakyan, Art

2018-03-01

Public awareness of inferior vena cava (IVC) filter-related controversies has been elevated by the Food and Drug Administration (FDA) safety communication in 2010. To examine population level trends in IVC filter utilization, complications, retrieval rates, and subsequent pulmonary embolism (PE) risk. A retrospective cohort study. Patients receiving IVC filters during 2005-2014 in New York State. IVC filter-specific complications, new PE occurrences and IVC filter retrievals were evaluated as time-to-event data using Kaplan-Meier analysis. Estimated cumulative risks were obtained at various timepoints during follow-up. There were 91,873 patients receiving IVC filters between 2005 and 2014 in New York State included in the study. The average patient age was 67 years and 46.6% were male. Age-adjusted rates of IVC filter placement increased from 48 cases/100,000 in 2005 to 52 cases/100,000 in 2009, and decreased afterwards to 36 cases/100,000 in 2014. The estimated risks of having an IVC filter-related complication and filter retrieval within 1 year was 1.5% [95% confidence interval (CI), 1.4%-1.6%] and 3.5% (95% CI, 3.4%-3.6%). One-year retrieval rate was higher post-2010 when compared with pre-2010 years (hazard ratio, 2.70; 95% CI, 2.50-2.91). Among the 58,176 patients who did not have PE events before or at the time of IVC filter placement, the estimated risk of developing subsequent PE at 1 year was 2.0% (95% CI, 1.9%-2.1%). Our findings suggest that FDA communications may be effective in modifying statewide clinical practices. Given the 2% observed PE rate following prophylactic IVC filter placement, large scale pragmatic studies are needed to determine contemporary safety and effectiveness of IVC filters.

Guenther tulip retrievable filter: why, when and how?

International Nuclear Information System (INIS)

Millward, S.F.

2001-01-01

Nonpermanent inferior vena cava (IVC) filters can be subdivided into temporary and retrievable filters. Temporary filters are attached to a catheter or guide wire. They have been extensively used in Europe, mainly for the prevention of pulmonary embolism (PE) during thrombolytic treatment for lower extremity deep vein thrombosis (DVT). However, the reported rate of recurrent PE in patients protected with a temporary filter appears to be similar, or even higher, than that seen in North American studies of thrombolytic treatment of DVT when no filter was used. Results obtained with temporary filters in other clinical situations have also been somewhat discouraging. Consequently, research efforts in North America with nonpermanent filters appear to have shifted predominantly to the study of retrievable filters. Retrievable filters, such as the Guenther Tulip filter (William Cook Europe, Bjaeverskov, Denmark) (Fig. 1), are permanent filters with a design feature (usually a hook that can be snared) to permit retrieval. They have an advantage over temporary filters in that they can be either left in place permanently or retrieved, whichever is most appropriate for a given patient. The Guenther Tulip filter is currently the only approved device from this versatile new class of retrievable filters. ln this article, I hope to offer some practical points on why, when and how the device should be used. (author)

Fracture and embolization of a Celect inferior vena cava filter strut to the liver: A Case Report

Energy Technology Data Exchange (ETDEWEB)

Kim, So Hee; Song, Yun Gyu [Dept. of Radiology, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon (Korea, Republic of)

2017-07-15

Inferior vena cava (IVC) filters are typically used for prophylaxis against pulmonary embolism. A new version of the Günther Tulip filter, the Celect IVC filter was introduced in April 2007. To the best of our knowledge, there are no reports commenting on Celect IVC filter fracture and fragment embolization to liver. We report a case in which the strut of the Celect IVC filter embolized to the liver.

Fracture and embolization of a Celect inferior vena cava filter strut to the liver: A Case Report

International Nuclear Information System (INIS)

Kim, So Hee; Song, Yun Gyu

2017-01-01

Inferior vena cava (IVC) filters are typically used for prophylaxis against pulmonary embolism. A new version of the Günther Tulip filter, the Celect IVC filter was introduced in April 2007. To the best of our knowledge, there are no reports commenting on Celect IVC filter fracture and fragment embolization to liver. We report a case in which the strut of the Celect IVC filter embolized to the liver

Complications of Celect, Günther tulip, and Greenfield inferior vena cava filters on CT follow-up: a single-institution experience.

Science.gov (United States)

McLoney, Eric D; Krishnasamy, Venkatesh P; Castle, Jordan C; Yang, Xiangyu; Guy, Gregory

2013-11-01

To evaluate and compare the rates of complications on follow-up computed tomography (CT) studies of patients with Celect, Günther Tulip, and Greenfield inferior vena cava (IVC) filters. Retrospective review of CT studies obtained 0-1,987 days after infrarenal placement of an IVC filter identified 255 Celect, 160 Tulip, and 50 Greenfield filters. Follow-up CT studies were independently evaluated by two observers for IVC perforation, contact with adjacent organs, and filter fracture. Multivariate analysis was performed to identify factors associated with higher rates of IVC perforation, including age, IVC diameter, sex, and history of malignancy. IVC perforation was observed in 126 of 255 Celect filters (49%) with a mean follow-up of 277 days, 69 of 160 Tulip filters (43%) with a mean follow-up of 437 days, and one of 50 Greenfield filters (2%) with a mean follow-up of 286 days. A significantly higher IVC perforation rate was observed in women (45.5%) compared with men (30.8%; P = .002) and in patients with a history of malignancy (43.7%) compared with patients with no history of malignancy (29.9%; P Tulip filters (0.6%), and none of 50 Greenfield filters. No significant difference was observed in IVC perforation rate between Celect and Tulip filters. Greenfield filters had a significantly lower rate of IVC perforation than Celect and Tulip filters. Higher IVC perforation rates were observed in women and patients with a history of malignancy. © SIR, 2013.

Late endovascular removal of Günther-Tulip inferior vena cava filter and stent reconstruction of chronic post-thrombotic iliocaval obstruction after 4753 days of filter dwell time: a case report with review of literature.

Science.gov (United States)

Doshi, Mehul Harshad; Narayanan, Govindarajan

2016-12-01

Chronic post-thrombotic obstruction of the inferior vena cava (IVC) or iliocaval junction is an uncommon complication of long indwelling IVC filter. When such an obstruction is symptomatic, endovascular treatment options include stent placement with or without filter retrieval. Filter retrieval becomes increasingly difficult with longer dwell times. We present a case of symptomatic post-thrombotic obstruction of the iliocaval junction related to Günther-Tulip IVC filter (Cook Medical Inc, Bloomington, IN) with dwell time of 4753 days, treated successfully with endovascular filter removal and stent reconstruction. Filter retrieval and stent reconstruction may be a treatment option in symptomatic patients with filter-related chronic IVC or iliocaval junction obstruction, even after prolonged dwell time.

Improving inferior vena cava filter retrieval rates with the define, measure, analyze, improve, control methodology.

Science.gov (United States)

Sutphin, Patrick D; Reis, Stephen P; McKune, Angie; Ravanzo, Maria; Kalva, Sanjeeva P; Pillai, Anil K

2015-04-01

To design a sustainable process to improve optional inferior vena cava (IVC) filter retrieval rates based on the Define, Measure, Analyze, Improve, Control (DMAIC) methodology of the Six Sigma process improvement paradigm. DMAIC, an acronym for Define, Measure, Analyze, Improve, and Control, was employed to design and implement a quality improvement project to increase IVC filter retrieval rates at a tertiary academic hospital. Retrievable IVC filters were placed in 139 patients over a 2-year period. The baseline IVC filter retrieval rate (n = 51) was reviewed through a retrospective analysis, and two strategies were devised to improve the filter retrieval rate: (a) mailing of letters to clinicians and patients for patients who had filters placed within 8 months of implementation of the project (n = 43) and (b) a prospective automated scheduling of a clinic visit at 4 weeks after filter placement for all new patients (n = 45). The effectiveness of these strategies was assessed by measuring the filter retrieval rates and estimated increase in revenue to interventional radiology. IVC filter retrieval rates increased from a baseline of 8% to 40% with the mailing of letters and to 52% with the automated scheduling of a clinic visit 4 weeks after IVC filter placement. The estimated revenue per 100 IVC filters placed increased from $2,249 to $10,518 with the mailing of letters and to $17,022 with the automated scheduling of a clinic visit. Using the DMAIC methodology, a simple and sustainable quality improvement intervention was devised that markedly improved IVC filter retrieval rates in eligible patients. Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.

Outcomes of inferior vena cava filter insertion in patients with lower extremity deep vein thrombosis for prevention of pulmonary thromboembolism: A single center retrospective analysis

Energy Technology Data Exchange (ETDEWEB)

Park, Byung Jin; Kim, Jae Kyu; Yim, Nam Yeol; Kim, Hyoung Ook [Dept. of Radiology, Chonnam National University Hospital, Gwangju (Korea, Republic of); Kang, Yang Jun [Dept. of Radiology, Chonnam National University Hwasun Hospital, Hwasun (Korea, Republic of)

2017-07-15

To evaluate the mid- and long-term outcomes of inferior vena cava (IVC) filter insertion in patients with underlying deep vein thrombosis for prevention of pulmonary thromboembolism, based on a single center experience. A total of 166 IVC filter insertion procedures in 160 patients, between February 2004 and December 2014, were retrospectively reviewed. Severity of deep vein thrombosis, indwelling time of the IVC filter, retrieval rate, and complication rate depending on the type of IVC filter were analyzed based on the patients' radiologic findings and medical records. IVC filter insertion procedures were successfully performed in all patients. Among the 99 attempts at filter retrieval, 91 trials succeeded (91.9%, 91/99) and 8 trials failed. Indwelling time of the IVC filter showed a positive correlation with failure of filter retrieval (p = 0.01). There was no procedure-related complication after all IVC filter insertion procedures. Eight delayed complications (5.0%, 8/160 patients with IVC filter insertion) were observed [caval thrombosis below the IVC filter (n = 7) and IVC penetration (n = 1)]. Günther Tulip filter was associated with a significant incidence of complication (p = 0.036). IVC filter insertion in patients with lower extremity deep vein thrombosis for prevention of pulmonary thromboembolism can be regarded as a safe treatment modality with an acceptable complication rate.

Outcomes of inferior vena cava filter insertion in patients with lower extremity deep vein thrombosis for prevention of pulmonary thromboembolism: A single center retrospective analysis

International Nuclear Information System (INIS)

Park, Byung Jin; Kim, Jae Kyu; Yim, Nam Yeol; Kim, Hyoung Ook; Kang, Yang Jun

2017-01-01

To evaluate the mid- and long-term outcomes of inferior vena cava (IVC) filter insertion in patients with underlying deep vein thrombosis for prevention of pulmonary thromboembolism, based on a single center experience. A total of 166 IVC filter insertion procedures in 160 patients, between February 2004 and December 2014, were retrospectively reviewed. Severity of deep vein thrombosis, indwelling time of the IVC filter, retrieval rate, and complication rate depending on the type of IVC filter were analyzed based on the patients' radiologic findings and medical records. IVC filter insertion procedures were successfully performed in all patients. Among the 99 attempts at filter retrieval, 91 trials succeeded (91.9%, 91/99) and 8 trials failed. Indwelling time of the IVC filter showed a positive correlation with failure of filter retrieval (p = 0.01). There was no procedure-related complication after all IVC filter insertion procedures. Eight delayed complications (5.0%, 8/160 patients with IVC filter insertion) were observed [caval thrombosis below the IVC filter (n = 7) and IVC penetration (n = 1)]. Günther Tulip filter was associated with a significant incidence of complication (p = 0.036). IVC filter insertion in patients with lower extremity deep vein thrombosis for prevention of pulmonary thromboembolism can be regarded as a safe treatment modality with an acceptable complication rate

Outcomes after inferior vena cava filter placement in cancer patients diagnosed with pulmonary embolism: risk for recurrent venous thromboembolism.

Science.gov (United States)

Coombs, Catherine; Kuk, Deborah; Devlin, Sean; Siegelbaum, Robert H; Durack, Jeremy C; Parameswaran, Rekha; Mantha, Simon; Deng, Kathy; Soff, Gerald

2017-11-01

Venous thromboembolism (VTE) is a common complication in cancer patients and anticoagulation (AC) remains the standard of care for treatment. Inferior vena cava (IVC) filters may also used to reduce the risk of pulmonary embolism, either alone or in addition to AC. Although widely used, data are limited on the safety and efficacy of IVC filters in cancer patients. We performed a retrospective review of outcomes after IVC filter insertion in a database of 1270 consecutive patients with cancer-associated pulmonary embolism (PE) at our institution between 2008 and 2009. Outcomes measured included rate of all recurrent VTE, recurrent PE, and overall survival within 12 months. 317 (25%) of the 1270 patients with PE had IVC filters placed within 30 days of the index PE event or prior to the index PE in the setting of prior DVT. Patients with IVC filters had markedly lower overall survival (7.3 months) than the non-IVC filter patients (13.2 months). Filter patients also had a lower rate of AC use at time of initial PE. There was a trend towards higher recurrent VTE in patients with IVC filters (11.9%) compared to non-filter patients (7.7%), but this was not significant (p = 0.086). The risk of recurrent PE was similar between the IVC filter cohort (3.5%) and non-filter group (3.5%, p = 0.99). Cancer patients receiving IVC filters had a similar risk of recurrent PE, but a trend towards more overall recurrent VTE. The filter patients had poorer overall survival, which may reflect a poorer cancer prognosis, and had greater contraindication to AC; therefore these patients likely had a higher inherent risk for recurrent VTE. A prospective study would be helpful for further clarification on the partial reduction in the recurrent PE risk by IVC filter placement in cancer patients.

Vessel Wall Reaction after Vena Cava Filter Placement

International Nuclear Information System (INIS)

Hoekstra, Arend; Elstrodt, Jan M.; Nikkels, Peter G.J.; Tiebosch, Anton T.M.G.

2002-01-01

Purpose: To evaluate the interaction between the Cordis Keeper vena caval filter and vessel wall in aporcine model.Methods: Implantation of the filter was performed in five pigs. Radiologic data concerning inferior vena cava(IVC) diameter and filter patency, filter leg span, and stability were collected. At 2 or 6 months post-implantation, histopathologic analysis of the IVC wall was performed.Results: All filters remained patent with no evidence of migration. However, at 6 months follow-up, two legs of one filter penetrated the vessel wall and were adherent to the liver. These preliminary results suggest that with the observed gradual increase in the filter span, the risk of caval wall penetration increases with time, especially in a relatively small IVC(average diameter 16 mm).Conclusion: The Cordis Keeper filter was well tolerated, but seems to be prone to caval wall penetration in the long term

Bilateral inferior vena cava filter insertion in a patient with duplication of the infrarenal vena cava.

LENUS (Irish Health Repository)

Leong, S

2010-06-19

BACKGROUND: Inferior vena cava (IVC) filter insertion is a commonly performed procedure for indications such as recurrent pulmonary emboli or contraindication to anticoagulation. Symptomatic duplication of the IVC is exceedingly rare with only a handful of cases being described in the literature. AIM: We report an unusual case of a patient with symptomatic duplication of the IVC. RESULT: A 53-year-old woman presented at our hospital for resection of a cerebral metastasis from a non-small cell lung cancer following a recent diagnosis of bilateral lower limb deep venous thrombosis. This required perioperative reversal of anticoagulation and IVC filter insertion. Conventional venography performed during filter insertion documented the existence of a duplicated IVC. CONCLUSION: We present a case of a symptomatic duplication of the IVC requiring filter insertion. We review the developmental anatomy of the IVC along with the diagnostic findings and management strategies available.

Spontaneous tilting after placement of the gunther-tulip inferior vena caval filter: a case report

International Nuclear Information System (INIS)

Seo, Tae Seok; Cha, In Ho; Seol, Hae Young; Park, Cheol Min

2006-01-01

Tilting of a deployed filter in the inferior vena cava (IVC) is a particular kind of periprocedural complication and this can reduce the filter's clot-trapping ability and increase the occlusion of the IVC at a later period. The authors report here on a case of spontaneous tilting of an inferior vena caval filter that was associated with thrombosis in the IVC within 2 weeks of the initially successful placement of the filter without tilting

Spontaneous tilting after placement of the gunther-tulip inferior vena caval filter: a case report

Energy Technology Data Exchange (ETDEWEB)

Seo, Tae Seok; Cha, In Ho; Seol, Hae Young; Park, Cheol Min [Guro Hospital, Korea University College of Medicine, Seoul (Korea, Republic of)

2006-10-15

Tilting of a deployed filter in the inferior vena cava (IVC) is a particular kind of periprocedural complication and this can reduce the filter's clot-trapping ability and increase the occlusion of the IVC at a later period. The authors report here on a case of spontaneous tilting of an inferior vena caval filter that was associated with thrombosis in the IVC within 2 weeks of the initially successful placement of the filter without tilting.

Are too many inferior vena cava filters used? Controversial evidences in different clinical settings: a narrative review.

Science.gov (United States)

Dalla Vestra, Michele; Grolla, Elisabetta; Bonanni, Luca; Pesavento, Raffaele

2018-03-01

The use of inferior vena cava filters to prevent pulmonary embolism is increasing mainly because of indications that appear to be unclearly codified and recommended. The evidence supporting this approach is often heterogeneous, and mainly based on observational studies and consensus opinions, while the insertion of an IVC filter exposes patients to the risk of complications and increases health care costs. Thus, several proposed indications for an IVC filter placement remain controversial. We attempt to review the proof on the efficacy and safety of IVC filters in several "special" clinical settings, and assess the robustness of the available evidence for any specific indication to place an IVC filter.

Safety and Efficacy of an Absorbable Filter in the Inferior Vena Cava to Prevent Pulmonary Embolism in Swine.

Science.gov (United States)

Huang, Steven Y; Eggers, Mitchell; McArthur, Mark J; Dixon, Katherine A; McWatters, Amanda; Dria, Stephen; Hill, Lori R; Melancon, Marites P; Steele, Joseph R; Wallace, Michael J

2017-12-01

Purpose To evaluate the immediate and long-term safety as well as thrombus-capturing efficacy for 5 weeks after implantation of an absorbable inferior vena cava (IVC) filter in a swine model. Materials and Methods This study was approved by the institutional animal care and use committee. Eleven absorbable IVC filters made from polydioxanone suture were deployed via a catheter in the IVC of 11 swine. Filters remained in situ for 2 weeks (n = 2), 5 weeks (n = 2), 12 weeks (n = 2), 24 weeks (n = 2), and 32 weeks (n = 3). Autologous thrombus was administered from below the filter in seven swine from 0 to 35 days after filter placement. Fluoroscopy and computed tomography follow-up was performed after filter deployment from weeks 1-6 (weekly), weeks 7-20 (biweekly), and weeks 21-32 (monthly). The infrarenal IVC, lungs, heart, liver, kidneys, and spleen were harvested at necropsy. Continuous variables were evaluated with a Student t test. Results There was no evidence of IVC thrombosis, device migration, caval penetration, or pulmonary embolism. Gross pathologic analysis showed gradual device resorption until 32 weeks after deployment. Histologic assessment demonstrated neointimal hyperplasia around the IVC filter within 2 weeks after IVC filter deployment with residual microscopic fragments of polydioxanone suture within the caval wall at 32 weeks. Each iatrogenic-administered thrombus was successfully captured by the filter until resorbed (range, 1-4 weeks). Conclusion An absorbable IVC filter can be safely deployed in swine and resorbs gradually over the 32-week testing period. The device is effective for the prevention of pulmonary embolism for at least 5 weeks after placement in swine. © RSNA, 2017.

The 6-F nitinol TrapEase inferior vena cava filter: results of a prospective multicenter trial.

Science.gov (United States)

Rousseau, H; Perreault, P; Otal, P; Stockx, L; Golzarian, J; Oliva, V; Reynaud, P; Raat, F; Szatmari, F; Santoro, G; Emanuelli, G; Nonent, M; Hoogeveen, Y

2001-03-01

The authors report the first results of a new 6-F symmetrically designed permanent nitinol inferior vena cava (IVC) filter, the Cordis TrapEase, evaluated in a multicenter prospective study with 6-months of follow-up. A total of 65 patients (29 men, 36 women) who ranged in age from 37 to 96 years (mean age, 68 years) and who were at high risk of pulmonary embolism (PE) were enrolled in 12 centers in Europe and Canada. The study was approved by the institutional review boards at all centers. Study objectives were to evaluate filter effectiveness, filter stability, and caval occlusion. Indications for filter placement were deep vein thrombosis with recurrent thromboembolism and/or free-floating thrombus with contraindication to anticoagulation in 37 patients, and complications in achieving adequate anticoagulation in 28 patients. Follow-up included clinical examination, plain film, Doppler ultrasound, CT scan, and nuclear medicine. The analysis of the data revealed a technical success of 95.4% (three filter-system related implantations not at the intended site, no events of filter tilting) and a clinical success of 100% at 6 months (no cases of symptomatic PE), the study primary endpoint. There were no cases (0%) of filter migration, insertion site thrombosis, filter fracture, or vessel wall perforation. During the study period, there were two cases of filter thrombosis: one case of early symptomatic thrombosis that was successfully treated in the hospital, and one case of nonsymptomatic filter thrombosis detected at 1-month follow-up, with spontaneous recanalization at 3 months. In the latter patient, some residual thrombus was still detected at 6 months. Of the study population of 65 patients, there were 23 deaths. These deaths were not related to the device or the implantation procedure but to the underlying disease process. This study demonstrates the new nitinol permanent IVC filter to be a safe and an effective device, with a low overall complication rate, for

Inferior Vena Cava Filter Limb Fracture with Embolization to the Right Ventricle.

Science.gov (United States)

Jackson, Bradley S; Sepula, Mykel; Marx, Jared T; Cannon, Chad M

2017-08-01

Inferior vena cava (IVC) filter and filter limb embolization is a known phenomenon, with a prevalence of up to 25% for certain filter types. Most commonly, the site of embolization is to the heart. Point-of-care ultrasound is an easily accessible imaging modality that should be utilized when considering IVC filter complications. A 28-year-old woman with a history of metastatic sarcoma and IVC filter placement for deep venous thrombosis presented to the Emergency Department (ED) for chest pain. Chest radiography was reviewed and originally thought to have no abnormalities. Chest computed tomography angiography was negative for filling defects or foreign bodies. A possible foreign body in the heart was noted by a radiologist's over-read of the original chest radiograph. An echocardiogram done by Cardiology was negative for foreign bodies or other abnormalities. Next, an emergency physician performed a bedside echocardiogram, with focused attention to the right side of the heart. An echogenic foreign body was visualized in the right ventricle. The patient was subsequently taken to the cardiac catheterization laboratory, where fluoroscopic visualization of a limb wire of an IVC filter within the right ventricle was obtained. That foreign body was subsequently removed successfully, along with removal of the broken IVC filter. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This case report highlights the utility of point-of-care ultrasound in the work-up of a patient with an embolized IVC filter wire. Chest pain patients frequently receive point-of-care echocardiography in the ED, and these ultrasound findings should be recognized and used to guide further treatment and consultation. Copyright © 2017 Elsevier Inc. All rights reserved.

Guenter Tulip Filter Retrieval Experience: Predictors of Successful Retrieval

International Nuclear Information System (INIS)

Turba, Ulku Cenk; Arslan, Bulent; Meuse, Michael; Sabri, Saher; Macik, Barbara Gail; Hagspiel, Klaus D.; Matsumoto, Alan H.; Angle, John F.

2010-01-01

We report our experience with Guenter Tulip filter placement indications, retrievals, and procedural problems, with emphasis on alternative retrieval techniques. We have identified 92 consecutive patients in whom a Guenter Tulip filter was placed and filter removal attempted. We recorded patient demographic information, filter placement and retrieval indications, procedures, standard and nonstandard filter retrieval techniques, complications, and clinical outcomes. The mean time to retrieval for those who experienced filter strut penetration was statistically significant [F(1,90) = 8.55, p = 0.004]. Filter strut(s) IVC penetration and successful retrieval were found to be statistically significant (p = 0.043). The filter hook-IVC relationship correlated with successful retrieval. A modified guidewire loop technique was applied in 8 of 10 cases where the hook appeared to penetrate the IVC wall and could not be engaged with a loop snare catheter, providing additional technical success in 6 of 8 (75%). Therefore, the total filter retrieval success increased from 88 to 95%. In conclusion, the Guenter Tulip filter has high successful retrieval rates with low rates of complication. Additional maneuvers such as a guidewire loop method can be used to improve retrieval success rates when the filter hook is endothelialized.

Establishment of an inferior vena cava filter database and interventional radiology led follow-up - retrieval rates and patients lost to follow-up.

Science.gov (United States)

Klinken, Sven; Humphries, Charlotte; Ferguson, John

2017-10-01

To evaluate the rates of inferior vena cava (IVC) filter retrieval and the number of patient's lost to follow-up, before and after the establishment of an IVC filter database and interventional radiology (inserting physician) led follow-up. On the 1st of June 2012, an electronic interventional radiology database was established at our Institution. In addition, the interventional radiology team took responsibility for follow-up of IVC filters. Data were prospectively collected from the database for all patients who had an IVC filter inserted between the 1st June 2012 and the 31st May 2014. Data on patients who had an IVC filter inserted between the 1st of June 2009 to the 31st of May 2012 were retrospectively reviewed. Patient demographics, insertion indications, filter types, retrieval status, documented retrieval decisions, time in situ, trackable events and complications were obtained in the pre-database (n = 136) and post-database (n = 118) cohorts. Attempted IVC filter retrieval rates were improved from 52.9% to 72.9% (P = 0.001) following the establishment of the database. The number of patients with no documented decision (lost to follow-up) regarding their IVC filter reduced from 31 of 136 (23%) to 0 of 118 patients (P = database group (113 as compared to 137 days, P = 0.129). Following the establishment of an IVC filter database and interventional radiology led follow-up, we demonstrate a significant improvement in the attempted retrieval rates of IVC filters and the number of patient's lost to follow-up. © 2017 The Royal Australian and New Zealand College of Radiologists.

Incidence and Outcomes of Inferior Vena Cava Filter Thrombus during Catheter-directed Thrombolysis for Proximal Deep Venous Thrombosis.

Science.gov (United States)

Jiang, Jianguang; Tu, Jianfei; Jia, Zhongzhi; Chen, Jiezhong; Cao, Haitao; Meng, Qingli; Fuller, Tyler A; Tian, Feng

2017-01-01

The aim of the study was to retrospectively evaluate the incidence and outcomes of inferior vena cava (IVC) filter thrombus during catheter-directed thrombolysis (CDT) for acute proximal deep venous thrombosis (DVT). From October 2006 to June 2015, patients diagnosed with acute proximal DVT and received CDT after a retrievable IVC filter was placed were included. The incidence, treatment, and outcomes of IVC filter thrombus during CDT were recorded and analyzed. A total of 189 patients (91 women, 98 men; mean age, 57.6 ± 9.8 years; range, 24-85 years) were included in this study. Among the 189 cases, the DVTs involved popliteal iliofemoral veins in 54 patients, iliofemoral veins in 113 patients, and iliac veins in 22 patients, of which 18 patients had thrombus extended into the IVC. Of the 189 patients, a total of 8 (4.2%, 8 of 189) patients were identified with IVC filter thrombus during CDT. The IVC filter thrombus was detected on a median of 2 days (range, 2-4 days) of CDT therapy, including small-size (n = 6) and large-size (n = 2) filter thrombus. Of the 8 patients, CDTs were performed with a mean 7.6 ± 1.1 days (range, 6-11 days) after the presence of symptoms for the treatment of proximal DVT, and all the IVC filter thrombi were lysed during CDT for the proximal DVT. All the IVC filters were removed successfully with a mean of 12.8 ± 0.93 days from placement. There were no procedure- or thrombolysis-related major complications, and no symptomatic pulmonary embolism breakthrough was seen in any of the patients after the filter placement. IVC filter thrombus during CDT for the acute proximal DVT is uncommon, and all of them did not need any additional treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

Creation of the permanent inferior vena cava filter for prevention of pulmonary artery embolism

Directory of Open Access Journals (Sweden)

Yа.O. Povar

2016-05-01

Full Text Available The aim of the study was to create a new permanent cava filter to improve functional capacities of the construction and achieve high clinical parameters. A new geometry of the permanent inferior vena cava filter was presented which has high blood clot-capturing ability, does not cause thrombus fragmentation, makes migration impossible. The inferior vena cava filter does not injure the vessel wall and preserves integrity under long-term use. The inferior vena cava filter installation is safe and controllable, the filter self-positioning and reposition are possible, the delivery system size is 6F, the blood flow changing is minimal.

Retrievable Inferior vena cava filters in pregnancy: Risk versus benefit?

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Crosby, David A; Ryan, Kevin; McEniff, Niall; Dicker, Patrick; Regan, Carmen; Lynch, Caoimhe; Byrne, Bridgette

2018-03-01

Venous thromboembolism remains one of the leading causes of maternal mortality in the developed world. Retrievable inferior vena cava (IVC) filters have a role in the prevention of lethal pulmonary emboli when anticoagulation is contraindicated or has failed [1]. It is unclear whether or not the physiological changes in pregnancy influence efficacy and complications of these devices. The decision to place an IVC filter in pregnancy is complex and there is limited information in terms of benefit and risk to the mother. The objective of this study was to determine the efficacy and safety of these devices in pregnancy and to compare these with rates reported in the general population. The aim of this study was report three recent cases of retrievable IVC filter use in pregnant women in our department and to perform a systematic review of the literature to identify published cases of filters in pregnancy. The efficacy and complication rates of these devices in pregnancy were estimated and compared to rates reported in the general population in a recent review [2]. Fisher's exact test was used for statistical analysis. In addition to our three cases, 16 publications were identified with retrievable IVC filter use in 40 pregnant women resulting in a total of 43 cases. There was no pulmonary embolus in the pregnant group (0/43) compared to 57/6291 (0.9%) in the general population. Thrombosis of the filter (2.3% vs. 0.9%, p = 0.33) and perforation of the IVC (7.0% vs 4.4%, p = 0.44) were more common in pregnancy compared to the general population but the difference was not statistically significant. Failure to retrieve the filter is more likely to occur in pregnancy (26% vs. 11%, p = 0.006) but this did not correlate with the type of device (p = 0.61), duration of insertion (p = 0.58) or mode of delivery (p = 0.37). Data for retrievable IVC filters in pregnancy is limited and there may be a publication bias towards complicated cases. This study

Transfemoral Filter Eversion Technique following Unsuccessful Retrieval of Option Inferior Vena Cava Filters: A Single Center Experience.

Science.gov (United States)

Posham, Raghuram; Fischman, Aaron M; Nowakowski, Francis S; Bishay, Vivian L; Biederman, Derek M; Virk, Jaskirat S; Kim, Edward; Patel, Rahul S; Lookstein, Robert A

2017-06-01

This report describes the technical feasibility of using the filter eversion technique after unsuccessful retrieval attempts of Option and Option ELITE (Argon Medical Devices, Inc, Athens, Texas) inferior vena cava (IVC) filters. This technique entails the use of endoscopic forceps to evert this specific brand of IVC filter into a sheath inserted into the common femoral vein, in the opposite direction in which the filter is designed to be removed. Filter eversion was attempted in 25 cases with a median dwell time of 134 days (range, 44-2,124 d). Retrieval success was 100% (25/25 cases), with an overall complication rate of 8%. This technique warrants further study. Copyright © 2017 SIR. Published by Elsevier Inc. All rights reserved.

Chronic Pain Syndrome Caused by a Bird's Nest Filter: First Case Report

International Nuclear Information System (INIS)

Al-Basheer, Mamoun Ahmad; Hamilton, Mark; Holdaway, Chris

2008-01-01

AimTo report the first case of a Bird's Nest IVC filter causing a chronic pain syndrome lasting 13 years through IVC wall penetration and subsequent break off of one of the filter struts.Materials and ResultsA 43-year-old female presented with a 13-year history of abdominal pain following uneventful insertion of a Bird's Nest vena cava filter through a right internal jugular percutanous approach. A year following the procedure, CT scan revealed one arm of the filter to be outside IVC borders. Nine years from the date of insertion the nature of the pain changed acutely following a five feet jump to more localized RUQ pain worse with twisting movements. A CT scan showed the strut to have pierced the IVC wall and penetrated the Unicate process of pancreas. Plain x-rays taken at different times in February 2006 showed one of the struts to be free floating in the peritoneal cavity. The floating strut was removed surgically from the wall of the Ileum. Postoperative recovery was uneventful and the patient was discharged pain free three days later.ConclusionChronic pain is an added complication of BNF devices. Although rare, it further emphasizes the need for long-term follow up of patients with IVC filters.

Experimental study of domestic inferior vena cava filter comparative to Antheor temporary vena cava filter in vitro

International Nuclear Information System (INIS)

Chen Guoping; Gu Jianping; Lou Wensheng; He Xu; Chen Liang; Su Haobo

2007-01-01

Objective: To evaluate clot capturing efficacy and stability of a new domestic designed inferior vena cava filter (DDIVCF) by comparing with Anthem temporary vena cava filter in vitro. Methods: (1)The DDIVCF and Antheor filter were tested in a flow model simulated the inferior vena cava (IVC) with 20 mm and 25 mm in diameter. The swine clots of four sizes were used: 3 mm x 20 mm, 3 mm x 30 mm, 6 mm x 20 mm, 6 mm x 30 mm. The clot capturing capacity was observed in horizontal position. (2) The stability was observed by measuring the comparative moving distance of 6 mm x 30 mm clots after clot trapping. Results: (1) DDIVCF capture rates were 34%, 56%, 82%, 94% and 26%, 38%, 56%, 86% for the 20 mm and 25 mm IVC models of four different sizes clots respectively, comparing with 54%, 64%, 86%, 96% and 38%, 44%, 68%, 90% respectively of Anthem temporary vena cava filter. The capture rates of DDIVCF and Antheor filter showed no significant differences of 3 mm x 30 mm, 6mm x 20 mm and 6 mm x 30 mm clots in 20 mm and 25 mm IVC models (P>0.05). (2) There was a few caudal migration with no significant difference (P>0.05). The filter migration distances were (0.6±0.3) cm and (1.0±0.1) cm respectively in the 20 mm and 25 mm IVC models with most clots of 6 mm x 30 mm were captured, comparing with (0.4±0.1) cm and (0.8 ±0.3) cm respectively for Antheor filter. Conclusions: DDIVCF is a stable and effective filter in an in-vitro model experiment but application in vivo would rather be further evaluated through more animal experiments. (authors)

Catheter-assisted retrieval of adhesive Geunther Tulip filter: preliminary experience

International Nuclear Information System (INIS)

Xiao Liang; Tong Jiajie; Xie Shiyang; Shen Jing

2011-01-01

Objective: To retrospectively summarize the technical experience in performing catheter-assisted retrieval of adhesive Geunther Tulip filter. Methods: During the period from November 2007 to October 2009, 95 patients with pulmonary embolism and acute deep vein thrombosis of lower limbs were admitted to authors' hospital. As simple snare technique failed to catch the adhesive Geunther Tulip filter previously implanted in inferior vena cava (IVC) in 6 patients (four males and two females with a mean age of 43.7 years), catheter-assisted retrieval of adhesive Geunther Tulip filter had to be carried out. The specific procedure was as follows. After phlebography of IVC confirmed that the filter's retrieval hook had adhered to IVC wall, the adhesion was separated with the help of catheter as well as goose-neck capturing device, then, the Geunther Tulip filter was retrieved. After the procedure, both anticoagulation and antibiotic medication were employed for 3-5 days. All the patients were followed up for 4-12 months. Vascular ultrasonography and pulmonary 3D CTA were re-examined in 6 months after primary operation. Results: All 6 adhesive Geunther Tulip filters were successfully removed with a success rate of 100%. The manipulation used in the procedure included catheter-twisting technique (n=1), catheter-looping technique (n=1) and catheter-snare looping technique (n=4). The mean operation time was 40.5 minutes (in the range of 17-78 minutes). The average filter-dwelling time was 46.7 days (ranging from 14 to 80 days). No thrombus formation in deep veins of lower extremity or pulmonary embolism occurred during the follow-up period. Conclusion: The catheter-assisted retrieval technique carries high retrieval rate for adhesive Geunther Tulip filter in IVC, it can markedly improve the retrieval success rate of Tulip IVC filter. (authors)

Bird's nest versus the Kimray-Greenfield inferior vena cava filter: Randomized clinical study

International Nuclear Information System (INIS)

Athanasoulis, C.A.; Roberts, A.C.; Brown, K.; Geller, S.C.; Waltman, A.C.; Eckstein, M.R.

1987-01-01

A randomized clinical study was conducted comparing the percutaneously introduced bird's nest inferior vena cava (IVC) filter and the Kimray-Greenfield IVC filter. Study end points included recurrent pulmonary embolism, new or worse leg venous stasis symptoms, IVC thrombosis, and ease of filter introduction. Of the 109 patients in the study, 58 were randomly assigned to the BN and 51 to the KG filter. Demographic factors were comparable between the two groups. Follow-up entailed cavography, noninvasive assessment of the femoral veins, and standardized telephone interviews. The follow-up period was extended to 1 year after filter insertion. Results for the bird's nest versus the Kimray-Greenfield filter respectively were as follows: death due to massive pulmonary embolism, 3% versus 5%; recurrent pulmonary embolism, 1.5% versus 7.5%; filter migration, 1.1% versus 0.0%; IVC thrombosis, 6% versus 2.5%; new or worse leg edema, 28.5% versus 22%; ease of introduction (qualitative), maximal versus minimal; patient discomfort (qualitative), minimal versus maximal. The authors conclude the bird's nest filter is better than the Kimray-Greenfield filter in terms of prevention of recurrent pulmonary embolism and ease of introduction. In terms of venous stasis, the bird's nest filter is not better and may be worse than the Kimray-Greenfield filter. Filter migration is a problem with the bird's nest filter

Differences in radial expansion force among inferior vena cava filter models support documented perforation rates.

Science.gov (United States)

Robins, J Eli; Ragai, Ihab; Yamaguchi, Dean J

2018-05-01

Inferior vena cava (IVC) filters are used in patients at risk for pulmonary embolism who cannot be anticoagulated. Unfortunately, these filters are not without risk, and complications include perforation, migration, and filter fracture. The most prevalent complication is filter perforation of the IVC, with incidence varying among filter models. To our knowledge, the mechanical properties of IVC filters have not been evaluated and are not readily available through the manufacturer. This study sought to determine whether differences in mechanical properties are similar to differences in documented perforation rates. The radial expansion forces of Greenfield (Boston Scientific, Marlborough, Mass), Cook Celect (Cook Medical, Bloomington, Ind), and Cook Platinum filters were analyzed with three replicates per group. The intrinsic force exerted by the filter on the measuring device was collected in real time during controlled expansion. Replicates were averaged and significance was determined by calculating analysis of covariance using SAS software (SAS Institute, Cary, NC). Each filter model generated a significantly different radial expansion force (P filter, followed by the Cook Celect and Greenfield filters. Radial force dispersion during expansion was greatest in the Cook Celect, followed by the Cook Platinum and Greenfield filters. Differences in radial expansion forces among IVC filter models are consistent with documented perforation rates. Cook Celect IVC filters have a higher incidence of perforation compared with Greenfield filters when they are left in place for >90 days. Evaluation of Cook Celect filters yielded a significantly higher radial expansion force at minimum caval diameter, with greater force dispersion during expansion. Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Prophylactic Placement of an Inferior Vena Cava Filter During Aspiration Thrombectomy for Acute Deep Venous Thrombosis of the Lower Extremity.

Science.gov (United States)

Kwon, Se Hwan; Park, So Hyun; Oh, Joo Hyeong; Song, Myung Gyu; Seo, Tae-Seok

2016-05-01

To evaluate the effect of an inferior vena cava (IVC) filter during aspiration thrombectomy for acute deep vein thrombosis (DVT) in the lower extremity. From July 2004 to December 2013, a retrospective analysis of 106 patients with acute DVT was performed. All patients received an IVC filter and were treated initially with aspiration thrombectomy. Among the 106 patients, DVT extension into the IVC was noted in 27 but was not evident in 79. We evaluated the presence of trapped thrombi in the filters after the procedure. The sizes of the trapped thrombi were classified into 2 grades based on the ratio of the maximum transverse length of the trapped thrombus to the diameter of the IVC (Grades I [≤ 50%] and II [> 50%]). A trapped thrombus in the filter was detected in 46 (43%) of 106 patients on final venograms. The sizes of the trapped thrombi were grade I in 12 (26.1%) patients and grade II in 34 (73.9%). Among the 27 patients with DVT extension into the IVC, 20 (74.1%) showed a trapped thrombus in the filter, 75% (15 of 20) of which were grade II. Among the 79 patients without DVT extension into the IVC, 26 (32.9%) showed a trapped thrombus in the IVC filter, 73% (19 of 26) of which were grade II. Thrombus migration occurred frequently during aspiration thrombectomy of patients with acute DVT in the lower extremity. However, further studies are needed to establish a standard protocol for the prophylactic placement of an IVC filter during aspiration thrombectomy. © The Author(s) 2016.

Mechanisms of Günther Tulip filter tilting during transfemoral placement.

Science.gov (United States)

Matsui, Y; Horikawa, M; Ohta, K; Jahangiri Noudeh, Y; Kaufman, J A; Farsad, K

The purpose of this study was to characterize the mechanisms of Günther Tulip filter (GTF) tilting during transfemoral placement in an experimental model with further validation in a clinical series. In an experimental study, 120 GTF placements in an inferior vena cava (IVC) model were performed using 6 configurations of pre-deployment filter position. The angle between the pre-deployment filter axis and IVC axis, and the proximity of the constrained filter legs to IVC wall prior to deployment were evaluated. The association of those pre-deployment factors with post-deployment filter tilting was analyzed. The association noted in the experimental study was then evaluated in a retrospective clinical series of 21 patients. In the experimental study, there was a significant association between the pre-deployment angle and post-deployment filter tilting (P<0.0001). With a low pre-deployment angle (≤5°), a significant association was noted between filter tilting and the proximity of the constrained filter legs to the far IVC wall (P=0.001). In a retrospective clinical study, a significant association between the pre-deployment angle and post-deployment filter tilting was also noted with a linear regression model (P=0.026). Significant association of the pre-deployment angle with post-deployment GTF tilting was shown in both the experimental and clinical studies. The experimental study also showed that proximity of filter legs is relevant when pre-deployment angle is small. Addressing these factors may result in a lower incidence of filter tilting. Copyright © 2017 Editions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

Serial repositioning of a Guenther tulip retrievable inferior vena cava filter in a pediatric patient

International Nuclear Information System (INIS)

Haider, Ehsan A.; Rosen, J. Choi; Torres, Carlos; Valenti, David A.

2005-01-01

We report an 11-year-old boy who required inferior vena cava (IVC) filtration for a prolonged period of time. A retrievable IVC filter was placed and repositioned three times, providing a total of 60 days of IVC filtration. The filter was removed when his risk of pulmonary embolus had decreased substantially. This is a relatively uncommon practice in the pediatric population. The technique is presented, and the available literature is reviewed. (orig.)

Entrapment of Guide Wire in an Inferior Vena Cava Filter: A Technique for Removal

International Nuclear Information System (INIS)

Abdel-Aal, Ahmed Kamel; Saddekni, Souheil; Hamed, Maysoon Farouk; Fitzpatrick, Farley

2013-01-01

Entrapment of a central venous catheter (CVC) guide wire in an inferior vena cava (IVC) filter is a rare, but reported complication during CVC placement. With the increasing use of vena cava filters (VCFs), this number will most likely continue to grow. The consequences of this complication can be serious, as continued traction upon the guide wire may result in filter dislodgement and migration, filter fracture, or injury to the IVC. We describe a case in which a J-tipped guide wire introduced through a left subclavian access without fluoroscopic guidance during CVC placement was entrapped at the apex of an IVC filter. We describe a technique that we used successfully in removing the entrapped wire through the left subclavian access site. We also present simple useful recommendations to prevent this complication.

Symptomatic caval penetration by a Celect inferior vena cava filter

International Nuclear Information System (INIS)

Bogue, Conor O.; John, Philip R.; Connolly, Bairbre L.; Rea, David J.; Amaral, Joao G.

2009-01-01

We report a case of penetration of the inferior vena cava (IVC) by all four primary struts of a Celect caval filter in a 17-year-old girl with Klippel-Trenaunay syndrome. The girl presented with acute lower abdominal and right leg pain 17 days after filter insertion. An abdominal radiograph demonstrated that the filter had moved caudally and that the primary struts had splayed considerably since insertion. Contrast-enhanced CT confirmed that all four primary struts had penetrated the IVC wall. There was a small amount of retroperitoneal hemorrhage. The surrounding vessels and viscera were intact. The filter was subsequently retrieved without complication. (orig.)

Vessel wall reaction after vena cava filter placement

NARCIS (Netherlands)

Hoekstra, A; Elstrodt, JM; Nikkels, PGJ; Tiebosch, ATMG

2002-01-01

Purpose: To evaluate the interaction between the Cordis Keeper vena caval filter and vessel wall in a porcine model. Methods: Implantation of the filter was performed in five pigs. Radiologic data concerning inferior vena cava (IVC) diameter and filter patency, filter leg span, and stability were

Permanently magnetized high gradient magnetic air filters for the nuclear industry

International Nuclear Information System (INIS)

Watson, J.H.P.

1995-01-01

This paper describes the structure and testing of two novel permanently magnetized magnetic filters for fine radioactive material. In the first filter the holes in the filter are left open as capture proceeds which means the pressure drop builds up only slowly. This filter is not suitable for composite particles which can be broken by mechanical forces. The second filter has been changed so as to strongly capture particles composed of fine particles weakly bound together which tend to break when captured. This uses a principle of assisted capture in which coarse particles aid the capture of the fine fragments. These filters have the following characteristics: (1) no external magnet is required, (2) no external power is required, (3) small in size and portable, (4) easily interchangeable, and (5) can be cleaned without demagnetizing by using a magnetic fluid which matches the susceptibility of the captured particles

Placement and retrieval of a Guenther tulip filter in patients with a free floating thrombus in inferior vena cava

International Nuclear Information System (INIS)

Seong, Min Hyun; Kim, Young Hwan; Lee, Sang Kwon; Choi, Jin Soo; Kim, Mi Jeong; Koo, Ja Hyun; Kim, Hyoung Tae; Cho, Won Hyun; Seong, Nak Kwan

2005-01-01

We wanted to assess the technical feasibility and clinical efficacy of the placement and retrieval of a Guenther Tulip filter for the prevention of fatal pulmonary embolism during the management of patients with a free floating thrombus in their inferior vena ca va (IVC). Six patients having a free floating thrombus in their IVC (three patients with an isolated free floating thrombus in the IVC that resulted from immobilization due to traumatic liver injury or cerebral infarction, two patients with coexisting deep vein thrombosis in the left lower extremity that was caused by May-Thurner syndrome, and one patient with coexisting deep vein thrombosis in the right lower extremity that was due to nephrotic syndrome and immobilization after hip joint replacement) underwent placement and retrieval of a Guenther Tulip filter. The placement of the filter was performed through the right internal jugular vein to prevent the risk of detachment of the thrombus during the procedure. Retrieval of filter was performed after the free floating thrombus of the IVC had disappeared on follow-up CT because of anticoagulation therapy, aspiration thrombectomy or catheter directed Urokinase thrombolysis. The Guenther Tulip filter was successfully placed in the IVC in all six patients and it was retrieved after the management of the free floating thrombus. The mean duration of the placement of the filter was 11 days (range:7-25 days). Two patients underwent placement of an iliac vein stent for the management of May-Thurner syndrome. Detachment of the free floating thrombus in the IVC and the subsequent thrombus entrapment in the filter were documented during aspiration thrombectomy or Urokinase thrombolysis in four patients. Recurrent thrombus didn't occur during the follow-up period (range:3-20 months) in five of the six patients. In one patient, a recurrent thrombus due to the discontinuance of anticoagulation therapy was identified at the filter detachment site of the IVC on the follow

Comparison of retrievable stents and permanent stents for Budd-Chiari syndrome due to obstructive inferior vena cava.

Science.gov (United States)

Bi, Yonghua; Chen, Hongmei; Ding, Penxu; Ren, Jianzhuang; Han, Xinwei

2018-05-30

To compare long-term outcomes of retrievable stents and permanent stents for BCS due to long-segment obstructive IVC. Between July 2000 and August 2016, 42 patients with BCS due to long-segment obstructive IVC were treated with retrievable stents (RS) and 41 patients were treated with permanent stents (PS). The retrievable stents was removed eventually after thrombus disappeared. Patients were subsequently followed-up by color Doppler sonography or CT scanning. All retrievable stent placements were successfully, and 37 retrievable stents were retrieved 8 to 29 days later. Forty-two stents were implanted in PS Group. One failure retrieval of retrievable stents occurred, and two failures of cannulations were found in PS Group. Two deaths may procedure-related and died from acute pulmonary thromboembolism perioperatively. One patient developed acute cerebral infarction and recovered after treatment. In PS Group, minor complications were found in 3 patients. The length of IVC lesion segment, length and thickness of IVC thrombus decreased significantly, and diameter of retrocaval IVC and diaphragm IVC increased significantly in both groups. During follow up, 3 patients died from liver failure in RS Group and 2 patients died in PS Group. RS Group showed a significantly higher primary patency rate than PS Group. Cumulative 1-, 3-, and 5-year secondary patency rates were 95.2%, 89.6%, 89.6% in RS Group, and 100%, 96.6%, 96.6% in PS Group (p= 0.7109). Retrievable stents is effective for BCS due to long-segment obstructive IVC, with a higher primary patency rate. This article is protected by copyright. All rights reserved.

Development of a predictive model for 6 month survival in patients with venous thromboembolism and solid malignancy requiring IVC filter placement.

Science.gov (United States)

Huang, Steven Y; Odisio, Bruno C; Sabir, Sharjeel H; Ensor, Joe E; Niekamp, Andrew S; Huynh, Tam T; Kroll, Michael; Gupta, Sanjay

2017-07-01

Our purpose was to develop a predictive model for short-term survival (i.e. filter placement in patients with venous thromboembolism (VTE) and solid malignancy. Clinical and laboratory parameters were retrospectively reviewed for patients with solid malignancy who received a filter between January 2009 and December 2011 at a tertiary care cancer center. Multivariate Cox proportional hazards modeling was used to assess variables associated with 6 month survival following filter placement in patients with VTE and solid malignancy. Significant variables were used to generate a predictive model. 397 patients with solid malignancy received a filter during the study period. Three variables were associated with 6 month survival: (1) serum albumin [hazard ratio (HR) 0.496, P filter placement can be predicted from three patient variables. Our predictive model could be used to help physicians decide whether a permanent or retrievable filter may be more appropriate as well as to assess the risks and benefits for filter retrieval within the context of survival longevity in patients with cancer.

Accuracy of computed tomography-intravenous cholangiography (CT-IVC) in detection of choledocholithiasis)

International Nuclear Information System (INIS)

Gibson, R.; Speer, A.G.; Collier, N.A.; Vincent, J.M.; Jardine, C.; Noack, K.

2002-01-01

Full text: The aim of the study was to determine the accuracy of computed tomography-intravenous cholangiography (CT-IVC) in the detection of choledocholithiasis, compared with endoscopic retrograde cholangiography (ERC). 65 patients undergoing ERC had CT-IVC within 24 hours prior to ERC. Helical CT-IVC was performed following intravenous infusion of 100ml Biliscopin (Schering, Berlin). 2mm beam collimation was used with axial reformats at 1.5mm intervals used for image interpretation. Patients with serum bilirubin levels>3 times normal were excluded. CT-IVC and ERC studies were interpreted independently, and studies were graded as positive, negative or indeterminate for the presence of ductal calculi. 65 patients had a median age of 56 years. Median serum bilirubin at the time of CT-IVC was 13 mmol/L (range 5-47). ERC was indeterminate in 3 patients (4.7%) and CT-IVC in 4 (6.3%). 23 patients had ductal calculi on ERC and CT-IVC was positive in 22 (sensitivity 96%). False positive rate for CT-IVC was 8.3% with positive and negative predictive values of 92% and 97% respectively. Stones' size range was 4-16mm. Of the 14 solitary stones, 10 were pound 5mm and 8 pound 4mm.The bilirubin level in the positive cases was within the normal range in 20, with a range of 7-37 mmol/L. CT-IVC is highly accurate for detection of ductal calculi, including single small calculi, in patients with a serum bilirubin of <3 times normal. Copyright (2002) Blackwell Science Pty Ltd

Percutaneous insertion of inferior vean cava filter:clinical results of 8 patients

International Nuclear Information System (INIS)

Bae, Kyung Soo; Shin, Hyun Woong; Park, No Hyuck; Ryeom, Hun Kyu; Kim, Yong Joo

1997-01-01

To evaluate the efficacy and clinical results of percutaneous insertion of inferior vena cava(IVC) filter. Over a two year period, eight IVC filters were placed in eight patients with pulmonary thromboembolism resulting from deep vein thrombosis of the legs. The indications for placement were contraindication to anticoagulation(3), and recurrent pulmonary embolism during anticoagulant therapy(5). Both femoral(7) and jugular(1) routes were used for percutaneous transvenous insertion. To delineate the caval anatomy and to ensure placement just caudal to the renal vein, a cavogram was obtained before filter placement. Bird's Nest (7) and Greenfield (1) filters were inserted. Follow-up information was obtained by means of duplex sonography, CT scan, abdominal radiograph, and perfusion scan of the lungs, followed by clinical evaluation. In all cases, procedures were technically successful. Placement complications occurred in three patients. In one, the filter was inadvertently placed above the iliac bifurcation; in the other two, prolapse of the Bird's Nest filter wire occurred. Occlusion of IVC occurred in two patients, and recurrent pulmonary embolism was suspected in one, who suffered from chest pain and short-ness of breath. In the other patients, there was no clinical evidence of recurrence of the pulmonary embolism. Insertion of an inferior vena cava filter is a safe and effective method for the prevention of pulmonary embolism when anticoagulant therapy is either ineffective or contraindicated

Inferior vena cava filter insertion through the popliteal vein: enabling the percutaneous endovenous intervention of deep vein thrombosis with a single venous access approach in a single session

Science.gov (United States)

Kim, Hyoung Ook; Kim, Jae Kyu; Park, Jin Gyoon; Yim, Nam Yeol; Kang, Yang Jun; Jung, Hye Doo

2016-01-01

PURPOSE We aimed to evaluate the efficiency of placing an inferior vena cava (IVC) filter through the same popliteal vein access site used for percutaneous endovenous intervention in patients with extensive lower extremity deep vein thrombosis. METHODS This retrospective study included 21 patients who underwent IVC filter insertion through the popliteal vein over a three-year period. Patient medical records were reviewed for the location of the deep vein thrombosis, result of filter removal, and total number of endovascular procedures needed for filter insertion and recanalization of the lower extremity venous system. Follow-up lower extremity computed tomography (CT) venography was also reviewed in each patient to assess the degree of filter tilt in the IVC. RESULTS All patients had extensive lower extremity deep vein thrombosis involving the iliac vein and/or femoral vein. Seventeen patients showed deep vein thrombosis of the calf veins. In all patients, IVC filter insertion and the recanalization procedure were performed during a single procedure through the single popliteal vein access site. In the 17 patients undergoing follow-up CT, the mean tilt angle of the filter was 7.14°±4.48° in the coronal plane and 8.77°±5.49° in the sagittal plane. Filter retrieval was successful in 16 of 17 patients (94.1%) in whom filter retrieval was attempted. CONCLUSION Transpopliteal IVC filter insertion is an efficient technique that results in low rates of significant filter tilt and enables a single session procedure using a single venous access site for filter insertion and percutaneous endovenous intervention. PMID:27559713

Are inferior vena cava filters effective for prophylaxis of critical pulmonary embolism in patients with cancer and coexisting venous thromboembolism?

International Nuclear Information System (INIS)

Deguchi, Juno; Nagayoshi, Mikiko; Onozuka, Atsuko

2008-01-01

Cancer sometimes causes venous thromboembolisms (VTE) including pulmonary embolisms (PE), which impedes aggressive treatment such as chemotherapy. From January 2003 to March 2007, there were 120 hospitalized patients with existing VTE in The University of Tokyo Hospital. Among them we reviewed 39 patients with cancer who required aggressive chemoradiotherapy and examined whether inferior vena cava (IVC) filtration was necessary in addition to ordinary anticoagulant therapy. The clinical stage of cancer was stage I in 7, stage II in 4, stage III in 11, and stage IV in 17. Most were advanced cancer. Of the 39, 9 underwent an IVC filter placement (filter group) and 30 did not (no-filter group). All of them received regular anticoagulant therapy. In the long-term follow up averaging 16.9 months, one patient of the filter group required discontinuation of chemotherapy due to symptomatic PE, but there was no such a case in the no-filter group. Filter-related complications such as IVC occlusion or migration did not occur. Computed tomography showed VTE in the long-term course in 27 out of 39 patients, and suggested increased thrombi in cases of recurrent cancer and those with poor outcome. Seventeen died of cancer but no one died of PE during the study. This study showed that IVC filters offered no beneficial effect for the patients with existing VTE who receive aggressive chemotherapy. (author)

Early and Late Retrieval of the ALN Removable Vena Cava Filter: Results from a Multicenter Study

International Nuclear Information System (INIS)

Pellerin, O.; Barral, F. G.; Lions, C.; Novelli, L.; Beregi, J. P.; Sapoval, M.

2008-01-01

Retrieval of removable inferior vena cava (IVC) filters in selected patients is widely practiced. The purpose of this multicenter study was to evaluate the feasibility and results of percutaneous removal of the ALN removable filter in a large patient cohort. Between November 2003 and June 2006, 123 consecutive patients were referred for percutaneous extraction of the ALN filter at three centers. The ALN filter is a removable filter that can be implanted through a femoral/jugular vein approach and extracted by the jugular vein approach. Filter removal was attempted after an implantation period of 93 ± 15 days (range, 6-722 days) through the right internal jugular vein approach using the dedicated extraction kit after control inferior vena cavography. Following filter removal, vena cavograms were obtained in all patients. Successful extraction was achieved in all but one case. Among these successful retrievals, additional manipulation using a femoral approach was needed when the apex of the filter was close to the IVC wall in two patients. No immediate IVC complications were observed according to the postimplantation cavography. Neither technical nor clinical differences between early and late filter retrieval were noticed. Our data confirm the safety of ALN filter retrieval up to 722 days after implantation. In infrequent cases, additional endovenous filter manipulation is needed to facilitate extraction.

Simon nitinol vena cava filters: effectiveness and complications

International Nuclear Information System (INIS)

Wolf, F.; Thurnher, S.; Lammer, J.

2001-01-01

Purpose: The aim of this retrospective analysis was to evaluate the clinical safety and effectiveness of the simon nitinol inferior vena cava filter (SNF) for prevention of pulmonary embolism. Patients and Methods: 117 patients (63 male, 54 female; aged 58.38 ± 14.59 years) underwent percutaneous implantation of an SNF from 1993 through 1999. Patient reports were retrospectively analysed for complications during and after implantation and deep venous thrombosis (DVT) and pulmonary embolism before and after implantation. Helical-CT with contrast media and plain abdominal radiography were performed on 35 patients, helical-CT alone on two patients. We checked the position and configuration of the SNF and looked for a perforation of the filter legs through the wall of the inferior vena cava (IVC). The IVC and deep pelvic veins were analysed for patency. Results: During implantation 10 of 117 (9%) patients had minor complications, major complications were reported in 0.9% (1/117). There was no significant increase in thrombosis of the deep pelvic veins and the IVC after implantation. Pulmonary re-embolism (PE) was documented in 9 out of 117 patients (7.7%). One out of the 35 examined patients (2.9%) showed a single strut fracture of the SNF. Tilting more than 15 was seen in 7 out of 37 patients (19%). Dislocation of the SNF more than 10 mm occurred in one out of 35 patients (2.9%), perforation through the wall of the IVC in all 37 patients. We found no occlusion of the IVC. (orig.) [de

Fundamentals: IVC and Computer Science

NARCIS (Netherlands)

Gozalvez, Javier; Haerri, Jerome; Hartenstein, Hannes; Heijenk, Geert; Kargl, Frank; Petit, Jonathan; Scheuermann, Björn; Tieler, Tessa; Altintas, O.; Dressler, F.; Hartenstein, H.; Tonguz, O.K.

The working group on “Fundamentals: IVC and Computer Science‿ discussed the lasting value of achieved research results as well as potential future directions in the field of inter- vehicular communication. Two major themes ‘with variations’ were the dependence on a specific technology (particularly

Long-Term Safety and Effectiveness of the “OptEase” Vena Cava Filter

International Nuclear Information System (INIS)

Kalva, Sanjeeva P.; Marentis, Theodore C.; Yeddula, Kalpana; Somarouthu, Bhanusupriya; Wicky, Stephan; Stecker, Michael S.

2011-01-01

Purpose: To assess the long-term safety and effectiveness of the OptEase inferior vena cava (IVC) filter. Materials and Methods: In this Institutional Review Board-approved, retrospective study, we reviewed data of 71 patients who received an OptEase filter at our institution from 2002 to 2007. Thirty-nine (55%) patients had symptoms of venous thromboembolism before filter placement. The indications for filter included contraindication to anticoagulation in 31 (44%) patients, prophylaxis against pulmonary embolism (PE) in 29 (41%) patients, and failure of anticoagulation in 11 (15%) patients. Procedure-related complications, such as symptomatic post-filter PE, deep venous thrombosis (DVT), IVC occlusion, and incidental imaging-evident filter-related complications, were recorded. Safety was assessed by the occurrence of filter-related complications during placement and follow-up. Effectiveness was assessed by the occurrence of post-filter PE. Results: Sixty-five (92%) filters were placed under fluoroscopy, and 6 (8%) were placed using intravascular ultrasound guidance. Seventy (99%) filters were placed successfully. Seven (10%) filters were placed in the suprarenal cava. Retrieval was attempted in 14 (20%) patients, and 12 filters were successfully retrieved. Clinical follow-up was available for 20 ± 21 months. Symptoms of postfilter PE and DVT occurred in 15% (n = 11) and 10% (n = 7) patients, respectively. None of these patients had computed tomography (CT)-proven PE, and only one had ultrasound-proven new DVT. One patient had symptomatic IVC occlusion. Follow-up abdominal CT in 20 patients showed thrombus in the filter in two of them. There were no instances of filter migration, filter tilt, or caval wall penetration. Conclusion: The OptEase filter appears to have an acceptable long-term safety profile. The filter was effective against PE.

Caval penetration by retrievable inferior vena cava filters: a retrospective comparison of Option and Günther Tulip filters.

Science.gov (United States)

Olorunsola, Olufoladare G; Kohi, Maureen P; Fidelman, Nicholas; Westphalen, Antonio C; Kolli, Pallav K; Taylor, Andrew G; Gordon, Roy L; LaBerge, Jeanne M; Kerlan, Robert K

2013-04-01

To compare the frequency of vena caval penetration by the struts of the Option and Günther Tulip cone filters on postplacement computed tomography (CT) imaging. All patients who had an Option or Günther Tulip inferior vena cava (IVC) filter placed between January 2010 and May 2012 were identified retrospectively from medical records. Of the 208 IVC filters placed, the positions of 58 devices (21 Option filters, 37 Günther Tulip filters [GTFs]) were documented on follow-up CT examinations obtained for reasons unrelated to filter placement. In cases when multiple CT studies were obtained after placement, each study was reviewed, for a total of 80 examinations. Images were assessed for evidence of caval wall penetration by filter components, noting the number of penetrating struts and any effect on pericaval tissues. Penetration of at least one strut was observed in 17% of all filters imaged by CT between 1 and 447 days following placement. Although there was no significant difference in the overall prevalence of penetration when comparing the Option filter and GTF (Option, 10%; GTF, 22%), only GTFs showed time-dependent penetration, with penetration becoming more likely after prolonged indwelling times. No patient had damage to pericaval tissues or documented symptoms attributed to penetration. Although the Günther Tulip and Option filters exhibit caval penetration at CT imaging, only the GTF exhibits progressive penetration over time. Copyright © 2013 SIR. Published by Elsevier Inc. All rights reserved.

Relationship between serum IV-C, β2-m levels and diabetic nephropathy

International Nuclear Information System (INIS)

Liu Lu; Zhang Mukun

2005-01-01

Objective: To investigate the relationship between the serum type IV collagen (IV-C), β 2 -micro globulin (β 2 -m) levels and diabetic nephropathy. Methods: Serum IV-C, β 2 -m levels were measured with RIA in 30 controls and 86 patients with type 2 diabetics mellitus (35 with diabetic nephropathy and 51 without nephropathy). Results: the serum levels of IV-C and β 2 -m in diabetic patients with nephropathy were significantly higher than those in controls (P 0.05). Conclusion: Serum IV-C and β 2 -m levels increased gradually as the diabetic nephropathy got more severe. They could be a sensitive marker for early diagnosis of development of diabetic nephropathy. (authors)

The initial experience of transjugular retrieval of Geunther Tulip inferior vena cava filters

International Nuclear Information System (INIS)

Xiao Liang; Shen Jing; Tong Jiajie; Li Haiwei; Xu Ke

2011-01-01

Objective: To explore the indications and technical procedures of transjugular retrieval of Geunther Tulip inferior vena cava filters. Methods: Seventy-four patients (40 males and 34 females with a mean age of 45.8 years) with acute lower extremity deep venous thrombosis encountered in our hospital from September 2007 to Mar 2009 were involved in this study. The onset of the disease was from one day to 14 days. Clinical symptoms included swelling, pain, cyanosis or pallescence of the affected limb with higher or normal skin temperature. Thirty-one patients who complicated with pulmonary embolism suffered from dyspnoea, chest pain, hemoptysis, etc. Implantation of Geunther Tulip retrievable inferior vena cava filters through femoral or right internal jugular vein was carried out, which was followed by intravenous transcatheter thrombolysis. Vascular ultrasound and angiography showed no fresh or free thrombus in 12-80 days after initial treatment, then the Geunther Tulip filter was taken out from right internal jugular vein, and inferior vena cavography was performed again. All patients accepted anticoagulation and antibiotic treatment for 3-5 days after operation. A follow-up lasting for 4-12 months was made. Results: Successful implantation of Geunther Tulip retrievable inferior vena cava filter with only one session was obtained in all 74 patients. During implantation procedure one filter became tilted 25 degrees. Successful removal of Geunther Tulip retrievable inferior vena cava filter was achieved in 40 patients in 41.3 days (12-80 days) after the filter was delivered, and the procedure cost only 5.8 minutes (1-115 minutes) with a successful rate of 97.6% (40/41). Failure of retrieval of IVC filter due to compact adhesion of the filter to IVC wall happened in one patient. Inferior vena cavography again confirmed that there was no any sign of vascular perforation or rupture. Retrieval of IVC filter was not performed in other 33 patients and no clinical

Endovascular Removal of Fractured Inferior Vena Cava Filter Fragments: 5-Year Registry Data with Prospective Outcomes on Retained Fragments.

Science.gov (United States)

Kesselman, Andrew J; Hoang, Nam Sao; Sheu, Alexander Y; Kuo, William T

2018-06-01

To evaluate the safety and efficacy of attempted percutaneous filter fragment removal during retrieval of fractured inferior vena cava (IVC) filters and to report outcomes associated with retained filter fragments. Over a 5-year period, 82 consecutive patients presenting with a fractured IVC filter were prospectively enrolled into an institutional review board-approved registry. There were 27 men and 55 women (mean, 47 y; range, 19-85 y). After main filter removal, percutaneous removal of fragments was attempted if they were deemed intravascular and accessible on preprocedural computed tomography (CT), cone-beam CT, and/or intravascular ultrasound; distal pulmonary artery (PA) fragments were left alone. A total of 185 fragments were identified (81 IVC, 33 PA, 16 cardiac, 2 hepatic vein, 1 renal vein, 1 aorta, 51 retroperitoneal). Mean filter dwell time was 2,183 days (range, 59-9,936 d). Eighty-seven of 185 fragments (47%) were deemed amenable to attempted removal: 65 IVC, 11 PA, 8 cardiac, 2 hepatic, and 1 aortic. Primary safety outcomes were major procedure-related complications. Fragment removal was successful in 78 of 87 cases (89.7%; 95% confidence interval [CI], 81.3-95.2). There were 6 minor complications with no consequence (6.9%; 95% CI, 2.6-14.4) involving intraprocedural fragment embolization and 1 major complication (1.1%; 95% CI, 0.0-6.2), a cardiac tamponade that was successfully treated. The complication rate from attempted cardiac fragment removal was 12.5% (1 of 8; 95% CI, 0.3-52.7). Among patients with retained cardiopulmonary fragments (n = 19), 81% remained asymptomatic during long-term clinical follow-up of 845 days (range, 386-2,071 d). Percutaneous removal of filter fragments from the IVC and proximal PAs is safe and effective overall, but attempted intracardiac fragment removal carries a higher risk of complication. Most residual filter fragments not amenable to percutaneous removal remain asymptomatic and may be monitored clinically

A novel permanently magnetised high gradient magnetic filter using assisted capture for fine particles

Energy Technology Data Exchange (ETDEWEB)

Watson, J.H.P. [Univ. of Southampton (United Kingdom)

1995-02-01

This paper describes the structure and properties of a novel permanently magnetised magnetic filter for fine friable radioactive material. Previously a filter was described and tested. This filter was designed so that the holes in the filter are left open as capture proceeds which means the pressure drop builds up only slowly. This filter is not suitable for friable composite particles which can be broken by mechanical forces. The structure of magnetic part of the second filter has been changed so as to strongly capture particles composed of fine particles weakly bound together which tend to break when captured. This uses a principle of assisted-capture in which coarse particles aid the capture of the fine fragments. The technique has the unfortunate consequence that the pressure drop across the filter rises faster as capture capture proceeds than the filter described previously. These filters have the following characteristics: (1) No external magnet is required. (2) No external power is required. (3) Small is size and portable. (4) Easily interchangeable. (5) Can be cleaned without demagnetising.

Failed Retrieval of an Inferior Vena Cava Filter During Pregnancy Because of Filter Tilt: Report of Two Cases

International Nuclear Information System (INIS)

McConville, R. M.; Kennedy, P. T.; Collins, A. J.; Ellis, P. K.

2009-01-01

Thromboembolic disease during pregnancy is an important cause of obstetric morbidity and mortality. Pregnant patients with venous thromboembolism are usually managed by conventional anticoagulation. However, this must be discontinued during vaginal or caesarian delivery to avoid haemorrhage and to reduce the risk of possible epidural haematoma. Retrievable inferior vena cava filters (IVCFs) offer protection against pulmonary embolism during this high-risk period, when anticoagulation is discontinued, while avoiding potential long-term sequelae of a permanent IVCF. Here we report two patients who presented in the third trimester of pregnancy with floating ileofemoral deep vein thrombosis. Both patients were initially treated with standard anticoagulation; however, shortly before delivery both patients had a retrievable IVCF placed in a suprarenal position. In both patients, retrieval failed at 28 days after insertion because of filter tilt. The timing and mechanism of filter tilt remains uncertain. We believe that a number of factors could have been involved, including change in the anatomic configuration with lateral displacement of the IVCF as a result of the gravid uterus as well as forceful uterine contractions during labour, which modified the shape and diameter of the IVC. We showed that failure to retrieve the IVCF has had considerable implications for the two young patients regarding long-term anticoagulation and have highlighted the need for further clinical trials regarding the safe use of retrievable IVCFs during pregnancy.

The study on the magnetic filter using the rotation of permanent magnets for separation of radioactive corrosion products

International Nuclear Information System (INIS)

Song, M.C.; Lee, K.J.

2004-01-01

Most of the insoluble radioactive corrosion products have the characteristic of showing strong ferrimagnetism. Along with the new development and production of permanent magnets which generate much stronger magnetic field than conventional permanent magnets, new type of magnetic filter that can separate radioactive corrosion products efficiently and eventually reduce the radiation exposure of the personnel at a nuclear power plant is suggested. This new type of separator with novel geometry consists of an inner and an outer magnet assembly, a coolant channel and a container surrounding the outer magnet assembly. The particulates are separated from the coolant by the alternating magnetic fields that are generated by shift arrangement of permanent magnets. This study describes of experimental results performed with the different flow rates, rotation velocities of magnet assemblies, particle size and various materials. The efficiency of magnetic filter tends to increase as the flow rate is lower, and particle size is bigger. The rotating velocity of magnet assembly has also some influences on the separation efficiency. This new magnetic filter shows good performance results in filtering magnetite, cobalt ferrite and nickel ferrite except hematite, which is a kind of anti-ferromagnetic material, from aqueous coolant simulation. At the above 5 μm of particle size, the separation efficiencies are over than 90%. (author)

Thrombolysis for treating deep venous thrombosis by high-dose urokinase: the usefulness of preventive placement of inferior vena cava filter

International Nuclear Information System (INIS)

Guo Jinhe; Teng Gaojun; He Shicheng; Qiu Haibo; Fang Wen; Zhu Guangyu; Deng Gang

2002-01-01

Objective: To investigate the feasibility and efficacy of high-dose urokinase thrombolysis for treating lower limb deep venous thrombosis (DVT) after inferior vena cava (IVC) filter placement. Methods: Thirteen patients of venographically proved DVT underwent preventive IVC filter placement for thrombolysis by high-dose urokinase. Antegrade infusion of high-dose urokinase was performed via the dorsalis pedis vein of the involved lower limb. The total dose of urokinase was 9 000 000 ∼ 16 000 000 units, and the procedure of thrombolysis was performed in ICU ward where the patients were closely monitored clinically and laboratorially. Results: A total of 13 IVC filters were successfully deployed without disposition and migration. The therapeutic effects were divided into four scales as follows: complete disappearance of the venous thrombosis and clinically asymptomatic (n = 2); remarkable recovery characterized by markedly improved clinical symptoms and venographically proved patent lumen in which the diameter was larger than 70% (n = 9); effective treatment indicating improved symptoms to some degrees and venographically proved patent lumen in which the diameter was smaller than 70% ( n = 2); and ineffective treatment (n = 0). No pulmonary embolism and hemorrhage occurred during the procedure of thrombolysis. Conclusion: High-dose urokinase for treating DVT is safe and effective after preventive placement of IVC filter

Bird's Nest Filter Causing Symptomatic Hydronephrosis Following Transmural Penetration of the Inferior Vena Cava

International Nuclear Information System (INIS)

Stacey, C.S.; Manhire, A.R.; Rose, D.H.; Bishop, M.C.

2004-01-01

We report a case of symptomatic hydronephrosis caused by transcaval penetration of a Bird's Nest filter. Perforation of the wall of the inferior vena cava (IVC) following insertion of a caval filter is a well-recognized complication. Whilst two cases of hydronephrosis have been described with Greenfield filters, no case involving a Bird's Nest filter has been reported previously

Outcomes and Direct Costs of Inferior Vena Cava Filter Placement and Retrieval within the IR and Surgical Settings.

Science.gov (United States)

Makary, Mina S; Kapke, Jordan; Yildiz, Vedat; Pan, Xueliang; Dowell, Joshua D

2018-02-01

To compare the outcomes and costs of inferior vena cava (IVC) filter placement and retrieval in the interventional radiology (IR) and surgical departments at a tertiary-care center. Retrospective review was performed of 142 sequential outpatient IVC filter placements and 244 retrievals performed in the IR suite and operating room (OR) from 2013 to 2016. Patient demographic data, procedural characteristics, outcomes, and direct costs were compared between cohorts. Technical success rates of 100% were achieved for both IR and OR filter placements, and 98% of filters were successfully retrieved by IR means, compared with 83% in the OR (P filter insertions, but IR retrievals required half the fluoroscopy time, with an average of 9 minutes vs 18 minutes in the OR (P = .02). There was no significant difference between cohorts in the incidences of complications for filter retrievals, but more postprocedural complications were observed for OR placements (8%) vs IR placements (1%; P = .05). The most severe complication occurred during an OR filter retrieval, resulting in entanglement of the snare device and conversion to an emergent open filter removal by vascular surgery. Direct costs were approximately 20% higher for OR vs IR IVC filter placements ($2,246 vs $2,671; P = .01). Filter placements are equally successfully performed in IR and OR settings, but OR patients experienced significantly higher postprocedural complication rates and incurred higher costs. In contrast, higher technical success rates and shorter fluoroscopy times were observed for IR filter retrievals compared with those performed in the OR. Copyright © 2017 SIR. Published by Elsevier Inc. All rights reserved.

New optional IVC filter for percutaneous retrieval - in vitro evaluation of embolus capturing efficiency

International Nuclear Information System (INIS)

Guenther, R.W.; Mossdorf, A.; Pfeffer, J.; Buecker, A.; Neuerburg, J.; Hoej, A.R.; Moelgaard-Nielsen, A.; Schmitz-Rode, T.

2005-01-01

Purpose: In-vitro evaluation of a new caval filter (Cook Celect Filter) developed for delayed percutaneous retrieval in comparison to the Guenther Tulip filter. Materials and Methods: The new Celect filter is constructed on the basis of the Tulip filter and consists of 4 primary anchoring legs and additional 8 thinner secondary wires to stabilize the filter and to guarantee adequate filtering efficiency. The filtering wires are of the same amount and equal distribution as the filtering wires of the Tulip filter. The secondary wires are arranged in such a way that percutaneous filter retrieval should be possible even if the wires are incorporated into the caval wall. In a flow model (tube size diameter 15-, diameter 22- and diameter 30 mm), the filter was exposed to single and multiple emboli (blood clots) of different sizes (3 x 5, 3 x 10, 5 x 10, 3 x 20, 5 x 20, 7 x 10, 7 x 20 to 10 x 24 mm) to analyse the embolus capturing efficiency under different conditions including eccentric and concentric, horizontal and vertical positions in comparison to the Tulip filter. All testing was carried out in SPSS analytic software; statistical significance was assumed for p-values <0.05. Results: The in-vitro embolus capturing efficiency of the Celect filter proved to be equivalent to the Tulip filter. In the single-embolus test, 91.6% of the clots were captured by the Celect filter and 87.2% by the Tulip filter (p=0.042). Large clots ranging from 7 x 10 to 10 x 24 mm were captured in all cases, whereas the capture rates for the 3 x 5-mm and 3 x 10-mm clots were lower. The filters captured significantly more clots in the concentric than in the eccentric location. There was no significant difference between the overall capture rates of the two filters in the multi-clot test (72.2% vs. 75.1%), which showed deterioration of filter function during multiple clot exposure. With the 15-mm tube, the Celect filter had a significantly higher capture rate than the Tulip filter, whereas it

Bedside intravascular ultrasound-guided inferior vena cava filter placement in medical-surgical intensive care critically-ill patients

Directory of Open Access Journals (Sweden)

Mohammad A. Abusedera

2015-09-01

Conclusions: Bedside IVUS-guided filter placement in medical-surgical critically ill patient in intensive care unit is a feasible, safe and reliable technique for IVC interruption. IVUS may be the most appropriate tool to guide filter insertion in obese patient.

Percutaneous sharp recanalization of a membranous IVC occlusion with an occlusion balloon as a needle target

Directory of Open Access Journals (Sweden)

Michael D. Rivers-Bowerman, MD, MSc, FRCPC

2017-09-01

Full Text Available A 50-year-old male with right upper quadrant symptoms and hepatic dysfunction was found to have multiple dilated hepatic veins (HVs with intrahepatic collateralization and membranous occlusion of the intrahepatic inferior vena cava (IVC consistent with primary Budd–Chiari syndrome. Venacavograms depicted drainage of the intrahepatic collaterals through a left-sided HV entering the IVC above the level of the occlusion. Sharp recanalization of the membranous IVC occlusion was performed with an occlusion balloon as a needle target under echocardiographic monitoring followed by balloon angioplasty with restoration of IVC patency. Clinical, laboratory, and venographic procedural success has been demonstrated to 9 months with minimal residual stenosis.

Denali, Tulip, and Option Inferior Vena Cava Filter Retrieval: A Single Center Experience.

Science.gov (United States)

Ramaswamy, Raja S; Jun, Emily; van Beek, Darren; Mani, Naganathan; Salter, Amber; Kim, Seung K; Akinwande, Olaguoke

2018-04-01

To compare the technical success of filter retrieval in Denali, Tulip, and Option inferior vena cava filters. A retrospective analysis of Denali, Gunther Tulip, and Option IVC filters was conducted. Retrieval failure rates, fluoroscopy time, sedation time, use of advanced retrieval techniques, and filter-related complications that led to retrieval failure were recorded. There were 107 Denali, 43 Option, and 39 Tulip filters deployed and removed with average dwell times of 93.5, 86.0, and 131 days, respectively. Retrieval failure rates were 0.9% for Denali, 11.6% for Option, and 5.1% for Tulip filters (Denali vs. Option p = 0.018; Denali vs. Tulip p = 0.159; Tulip vs. Option p = 0.045). Median fluoroscopy time for filter retrieval was 3.2 min for the Denali filter, 6.75 min for the Option filter, and 4.95 min for the Tulip filter (Denali vs. Option p Option p = 0.67). Advanced retrieval techniques were used in 0.9% of Denali filters, 21.1% in Option filters, and 10.8% in Tulip filters (Denali vs. Option p Option p Option filter when compared to both the Denali and Tulip filters. Retrieval of the Denali filter required significantly less amount of fluoroscopy time and use of advanced retrieval techniques when compared to both the Option and Tulip filters. The findings of this study indicate easier retrieval of the Denali and Tulip IVC filters when compared to the Option filter.

Sonographic aorta/IVC cross-sectional area index for evaluation of dehydration in children.

Science.gov (United States)

Kwon, Hyuksool; Jung, Jae Yun; Lee, Jin Hee; Kwak, Young Ho; Kim, Do Kyun; Jung, Jin Hee; Chang, Ik Wan; Kim, Kyuseok

2016-09-01

Current studies have not found sufficient evidence to encourage the use of ultrasound for assessing dehydration in children. We introduce a new sonographic parameter, the "aorta/inferior vena cava (IVC) cross-sectional area index" (Ao/IVCA) measured just inferior to the xiphoid process, for the effective evaluation of dehydration in children. This is a prospective, observational study. We enrolled children who presented to the pediatric emergency department (PED) between May 2014 and January 2015. We measured the maximum diameter of the aorta from inner wall to inner wall, and the long and short axis diameters of IVC using a convex array transducer. Ao/IVCA was calculated and compared with aorta/IVC maximal diameter index (Ao/IVCD) and the clinical dehydration scale (CDS). A total of 34 children were enrolled. We found a statistically significant correlation between Ao/IVCA and CDS (R(2) = 0.30; P dehydration. The diagnostic performance of Ao/IVCA for dehydration might be higher than that of the method that uses the maximum diameter of IVC and the aorta. Copyright © 2016 Elsevier Inc. All rights reserved.

Nursing care of the complications caused by vena cava filter placement and thrombolytic therapy

International Nuclear Information System (INIS)

Ma Congfeng; Tan Meifang; Fu Bing; Luo Chunhua; Jiang Fengjiao

2011-01-01

Objective: To discuss the nursing care and observation measures for the complications occurred after vena cava filter placement and thrombolytic therapy. Methods: During the period of July 2007-March 2010, vena cava filter placement and thrombolytic therapy were employed in 70 patients. The observation for the main procedure-related complications was made. The main complications included bleeding tendency, pulmonary embolism, filter migration or loss, thrombus formation within filter, IVC perforation due to filter, venous insufficiency and skin blisters of the affected lower extremity. Results: The total effective rate of thrombolytic treatment in 70 patients was 95.7%. As reasonable and effective nursing care measures were implemented, no major complications, such as pulmonary embolism, filter migration or loss,thrombus formation within filter, IVC perforation due to filter, infection, etc. occurred. The other complications developed in some patients,which included hematuria (n=4), bleeding at puncturing site (n=3), bleeding at abdominal incision (n=3), subcutaneous ecchymosis (n=3) and skin vesicles of diseased limb (n=3), all of which were cured after proper management. Conclusion: Postoperative nursing is a kind of prospective nursing care, the primary purpose of which is to prevent the occurrence of the potential complications after surgery. Therefore, solid fundamental knowledge, careful observation ability and strong consciousness of responsibility are most important.(authors)

Endovascular Repair of a Perforation of the Vena Caval Wall Caused by the Retrieval of a Gunther Tulip Filter After Long-Term Implantation

International Nuclear Information System (INIS)

Morishita, Hiroyuki; Yamagami, Takuji; Matsumoto, Tomohiro; Takeuchi, Yoshito; Sato, Osamu; Nishimura, Tsunehiko

2011-01-01

Symptomatic penetration of the inferior vena cava (IVC) wall reportedly occurs in 0.3% of patients in whom a filter has been implanted, and it causes injury to the adjacent structures (Bogue et al. in Pediatr Radiol 39(10):1110–1113, 1; Brzezinski et al. in Burns 32(5):640–643, 2). We succeeded in the endovascular repair of perforation of the IVC wall occurring during the retrieval of a penetrated Gunther tulip vena cava filter (Cook, Bjaeverskov, Denmark) after long-term implantation.

Accuracy of computed tomographic intravenous cholangiography (CT-IVC) with iotroxate in the detection of choledocholithiasis

International Nuclear Information System (INIS)

Gibson, Robert N.; Vincent, Janette M.; Speer, Tony; Noack, Keith; Collier, Neil A.

2005-01-01

To determine the accuracy of computed tomographic intravenous cholangiography (CT-IVC) for detection of choledocholithiasis. Sixty-five patients undergoing endoscopic retrograde cholangiography (ERC) underwent CT-IVC prior to ERC, using a single detector helical CT following intravenous infusion of 100 ml iotroxate. Patients with bilirubin levels >3 times normal were excluded. ERC was indeterminate in three patients (4.7%) and CT-IVC in four (6.3%). Twenty-three patients had ductal calculi at ERC, and CT-IVC was positive in 22, with two false positives and one false negative: sensitivity 95.6%, specificity 94.3%. Stones were multiple in nine and solitary in 14. Of the 14 solitary stones, ten were ≤5 mm and eight were ≤4 mm. The bilirubin level in positive cases was within normal in 20. Maximum intensity projection (MIP) reformats showed stones in only 27% of cases and surface rendered (SR) reformats in none. CT-IVC is highly accurate for detection of ductal calculi, including single small calculi, with a normal or near normal serum bilirubin. Axial images should be used for interpretation rather than MIP or SR reformats. (orig.)

Project Termination Report. Title IV-C Classroom Management Project. ESEA Title IV-C, August 29, 1981 - September 30, 1982.

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Halasa, Ofelia; Theus, Frank

This report provides a summary description of the Title IV-C Classroom Management Project conducted in the Cleveland (Ohio) Public Schools. The purpose of this project was to develop and pilot test a resource handbook designed to improve elementary and secondary school teachers' ability to organize and manage their classrooms. The development of…

Mechanism for the tilting of Geunther Tulip inferior vena cava filter inserted via femoral vein: an experimental study in vitro

International Nuclear Information System (INIS)

Xiao Liang; Shen Jing; Huang Desheng; Xu Ke

2011-01-01

Objective: To clarify the mechanism causing the tilting of Geunther Tulip inferior Vena Cava filter (GTF) which is inserted via femoral vein access by means of the experiment in vitro. Methods: The caval model was established by placing one 25 mm × 10 cm Dacron graft and two 10 mm × 20 cm Dacron grafts into a transparent bifurcate glass tube. The study consisted of two groups: right straight group (G RS ) (n=100) and left straight group (G LS ) (n=100). The distance (D CH ) between the caval right wall and the hook was measured. The degree of tilting (DT) was classified into 5 grades and the data were recorded. Before and after the GTF was released, the angle (A CM1,2 ) between the axis of IVC and the metal mount, the distance (D CM1,2 ) between the caval right wall and the metal mount, the angle (A CF ) between the axis of IVC and the axis of the filter and the diameter of IVC (D IVC ) were measured separately. Results: The degree of GTF tilting in each group revealed a divergent tendency. In Group RS, the apex of the filter tended to be grade Ⅲ compared that in Group LS (59% vs 36%, P=0.003). The differences in most variables between G RS and G LS were considered as statistical significance. Significant positive correlation existed between A CM1 and A CF , A CM1 -A CM2 and D CH1 -D CH2 in each group, respectively, while significant negative association was also existed between D CH1 and A CF in each group. Conclusion: The tilting angle of GTF filter axis before it is released is a major cause of the occurrence of femoral GTF filter tilting. (authors)

Sonographic evaluation of intravascular volume status: Can internal jugular or femoral vein collapsibility be used in the absence of IVC visualization?

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Alistair Kent

2015-01-01

Full Text Available Introduction: Inferior vena cava collapsibility index (IVC-CI has been shown to correlate with both clinical and invasive assessment of intravascular volume status, but has important limitations such as the requirement for advanced sonographic skills, the degree of difficulty in obtaining those skills, and often challenging visualization of the IVC in the postoperative patient. The current study aims to explore the potential for using femoral (FV or internal jugular (IJV vein collapsibility as alternative sonographic options in the absence of adequate IVC visualization. Methods: A prospective, observational study comparing IVC-CI and Fem- and/or IJV-CI was performed in two intensive care units (ICU between January 2012 and April 2014. Concurrent M-mode measurements of IVC-CI and FV- and/or IJV-CI were collected during each sonographic session. Measurements of IVC were obtained using standard technique. IJV-CI and FV-CI were measured using high-frequency, linear array ultrasound probe placed in the corresponding anatomic areas. Paired data were analyzed using coefficient of correlation/determination and Bland-Altman determination of measurement bias. Results: We performed paired ultrasound examination of IVC-IJV (n = 39 and IVC-FV (n = 22, in 40 patients (mean age 54.1; 40% women. Both FV-CI and IJV-CI scans took less time to complete than IVC-CI scans (both, P < 0.02. Correlations between IVC-CI/FV-CI (R 2 = 0.41 and IVC-CI/IJV-CI (R 2 = 0.38 were weak. There was a mean -3.5% measurement bias between IVC-CI and IJV-CI, with trend toward overestimation for IJV-CI with increasing collapsibility. In contrast, FV-CI underestimated collapsibility by approximately 3.8% across the measured collapsibility range. Conclusion: Despite small measurement biases, correlations between IVC-CI and FV-/IJV-CI are weak. These results indicate that IJ-CI and FV-CI should not be used as a primary intravascular volume assessment tool for clinical decision support in

CC8 MRSA strains harboring SCCmec type IVc are predominant in Colombian hospitals.

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J Natalia Jiménez

Full Text Available BACKGROUND: Recent reports highlight the incursion of community-associated MRSA within healthcare settings. However, knowledge of this phenomenon remains limited in Latin America. The aim of this study was to evaluate the molecular epidemiology of MRSA in three tertiary-care hospitals in Medellín, Colombia. METHODS: An observational cross-sectional study was conducted from 2008-2010. MRSA infections were classified as either community-associated (CA-MRSA or healthcare-associated (HA-MRSA, with HA-MRSA further classified as hospital-onset (HAHO-MRSA or community-onset (HACO-MRSA according to standard epidemiological definitions established by the U.S. Centers for Disease Control and Prevention (CDC. Genotypic analysis included SCCmec typing, spa typing, PFGE and MLST. RESULTS: Out of 538 total MRSA isolates, 68 (12.6% were defined as CA-MRSA, 243 (45.2% as HACO-MRSA and 227 (42.2% as HAHO-MRSA. The majority harbored SCCmec type IVc (306, 58.7%, followed by SCCmec type I (174, 33.4%. The prevalence of type IVc among CA-, HACO- and HAHO-MRSA isolates was 92.4%, 65.1% and 43.6%, respectively. From 2008 to 2010, the prevalence of type IVc-bearing strains increased significantly, from 50.0% to 68.2% (p = 0.004. Strains harboring SCCmec IVc were mainly associated with spa types t1610, t008 and t024 (MLST clonal complex 8, while PFGE confirmed that the t008 and t1610 strains were closely related to the USA300-0114 CA-MRSA clone. Notably, strains belonging to these three spa types exhibited high levels of tetracycline resistance (45.9%. CONCLUSION: CC8 MRSA strains harboring SCCmec type IVc are becoming predominant in Medellín hospitals, displacing previously reported CC5 HA-MRSA clones. Based on shared characteristics including SCCmec IVc, absence of the ACME element and tetracycline resistance, the USA300-related isolates in this study are most likely related to USA300-LV, the recently-described 'Latin American variant' of USA300.

Venous Thromboembolism After Removal of Retrievable Inferior Vena Cava Filters

International Nuclear Information System (INIS)

Yamagami, Takuji; Tanaka, Osamu; Yoshimatsu, Rika; Miura, Hiroshi; Nishimura, Tsunehiko

2010-01-01

The purpose of this study was to examine the incidence of new or recurrent venous thromboembolism (VTE) after retrieval of inferior vena cava (IVC) filters and risk factors associated with such recurrence. Between March 2001 and September 2008, at our institution, implanted retrievable vena cava filters were retrieved in 76 patients. The incidence of new or recurrent VTE after retrieval was reviewed and numerous variables were analyzed to assess risk factors for redevelopment of VTE after filter retrieval. In 5 (6.6%) of the 76 patients, redevelopment or worsening of VTE was seen after retrieval of the filter. Three patients (4.0%) had recurrent deep venous thrombosis (DVT) in the lower extremities and 2 (2.6%) had development of pulmonary embolism, resulting in death. Although there was no significant difference in the incidence of new or recurrent VTE related to any risk factor investigated, a tendency for development of VTE after filter retrieval was higher in patients in whom DVT in the lower extremities had been so severe during filter implantation that interventional radiological therapies in addition to traditional anticoagulation therapies were required (40% in patients with recurrent VTE vs. 23% in those without VTE; p = 0.5866 according to Fisher's exact probability test) and in patients in whom DVT remained at the time of filter retrieval (60% in patients with recurrent VTE vs. 37% in those without VTE; p = 0.3637). In conclusion, new or recurrent VTE was rare after retrieval of IVC filters but was most likely to occur in patients who had severe DVT during filter implantation and/or in patients with a DVT that remained at the time of filter retrieval. We must point out that the fatality rate from PE after filter removal was high (2.6%).

A permanently magnetized high gradient magnetic filter for glove-box cleaning and increasing HEPA filter life

International Nuclear Information System (INIS)

Watson, J.H.P.; Boorman, C.H.

1991-01-01

The purpose of this paper is to describe the structure and testing of a permanently magnetized magnetic filter on simulants for radioactive material. The experimental work was carried out at British Nuclear Fuels plc, Sellafield, England and in CEN/SCK, Mol, Belgium using Cr powder which is a good magnetic simulant for PuO 2 . The basis of the use of such a filter in the nuclear industry relies on the fact that much of the radioactive material is paramagnetic. In the last twenty years a separation technique has been developed which allows weakly paramagnetic particles of colloidal size to be separated from fluid which passes through the separator. This method is called high gradient magnetic separation (HGMS) and is accomplished by magnetizing a fine ferromagnetic wire matrix by an externally applied magnetic field. This paper describes a new approach to this problem, by using a magnetically hysteretic material to construct the ferromagnetic matrix, it has been possible to provide a magnetic field in the region of the matrix and also have a residual magnetization within the matrix. This provides extremely compact magnetic separation systems. There are some subtle differences between this separation system and conventional HGMS which makes the radial feed system, with all its advantages, almost mandatory for hysteretic HGMS

Correlation of inferior vena cava (ivc) diameter and central venous pressure (cvp) for fluid monitoring in icu

International Nuclear Information System (INIS)

Khalil, A.; Hayat, A.

2015-01-01

To determine intravascular fluid status in critically ill patients using inferior vena cava diameter and correlating it with central venous pressure. Study Design: Cross sectional study. Place and Duration of Study: Intensive care department, Military Hospital Rawalpindi from Jan 2013 to Aug 2013. Material and Methods: We included 115 adult patients of both genders in age range of 18 to 87 years by consecutive sampling admitted in intensive care unit. Ultrasound guided IVC diameter was assessed in supine patients. Data was simultaneously collected from the CVP catheter. Variables included in study were age, gender, CVP, IVC diameter. Results: CVP ranged from -4 to 26 cm H/sub 2/O with mean of 8 cm H/sub 2/O (SD = 6.24). Mean IVC diameters increased with increase in CVP. Correlation between CVP and max IVC diameter was moderate and significant (r = 0.53, p < 0.001). Correlation between CVP and min IVC diameter was also moderate and significant (r = 0.58, p < 0.001). Conclusion: A simple bedside sonography of inferior vena cava diameter correlates well with extremes of CVP values and can be helpful in assessing intravascular fluid status in these patients. (author)

Tine after tine: a varied approach to the removal of a long-standing IVC filter

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Andrew Delozier

2017-06-01

Full Text Available Inferior vena cava filters are important tools used to help prevent life-threatening pulmonary embolisms in hospitalized patients with contraindications to pharmacological prophylactic anticoagulation. This is a case report of a patient who had an inferior vena cava filter placed after a traumatic subdural hematoma. He made a complete recovery but was lost to follow-up until he presented 1825 days after filter deployment with abdominal pain discovered to be from penetration of the filter tines outside the lumen and into adjacent structures. We describe a case complicated by fibrotic tine entrapment with penetration to surrounding structures and discuss the technical approach used to free and eventually remove the long-standing filter.

Development of moving alternating magnetic filter using permanent magnet for removal of radioactive corrosion product from nuclear power plant

International Nuclear Information System (INIS)

Song, M. C.; Kim, S. I.; Lee, K. J.

2002-01-01

Radioactive Corrosion Products (CRUD) which are generated by the neutron activation of general corrosion products at the nuclear power plant are the major source of occupational radiation exposure. Most of the CRUD has a characteristic of showing strong ferrimagnetisms. Along with the new development and production of permanent magnet (rare earth magnet) which generates much stronger magnetic field than the conventional magnet, new type of magnetic filter that can separate CRUD efficiently and eventually reduce radiation exposure of personnel at nuclear power plant is suggested. This separator consists of inner and outer magnet assemblies, coolant channel and container surrounding the outer magnet assembly. The rotational motion of the inner and outer permanent magnet assemblies surrounding the coolant channel by driving motor system produces moving alternating magnetic fields in the coolant channel. The CRUD can be separated from the coolant by the moving alternating magnetic field. This study describes the results of preliminary experiment performed with the different flow rates of coolant and rotation velocities of magnet assemblies. This new magnetic filter shows better performance results of filtering the magnetite at coolant (water). Flow rates, rotating velocities of magnet assemblies and particle sizes turn out to be very important design parameters

The Need for Anticoagulation Following Inferior Vena Cava Filter Placement: Systematic Review

International Nuclear Information System (INIS)

Ray, Charles E.; Prochazka, Allan

2008-01-01

Purpose. To perform a systemic review to determine the effect of anticoagulation on the rates of venous thromboembolism (pulmonary embolus, deep venous thrombosis, inferior vena cava (IVC) filter thrombosis) following placement of an IVC filter. Methods. A comprehensive computerized literature search was performed to identify relevant articles. Data were abstracted by two reviewers. Studies were included if it could be determined whether or not subjects received anticoagulation following filter placement, and if follow-up data were presented. A meta-analysis of patients from all included studies was performed. A total of 14 articles were included in the final analysis, but the data from only nine articles could be used in the meta-analysis; five studies were excluded because they did not present raw data which could be analyzed in the meta-analysis. A total of 1,369 subjects were included in the final meta-analysis. Results. The summary odds ratio for the effect of anticoagulation on venous thromboembolism rates following filter deployment was 0.639 (95% CI 0.351 to 1.159, p = 0.141). There was significant heterogeneity in the results from different studies [Q statistic of 15.95 (p = 0.043)]. Following the meta-analysis, there was a trend toward decreased venous thromboembolism rates in patients with post-filter anticoagulation (12.3% vs. 15.8%), but the result failed to reach statistical significance. Conclusion. Inferior vena cava filters can be placed in patients who cannot receive concomitant anticoagulation without placing them at significantly higher risk of development of venous thromboembolism

A magnetic filter with permanent magnets on the basis of rare earths

International Nuclear Information System (INIS)

Zezulka, V.Vaclav; Straka, Pavel; Mucha, Pavel

2004-01-01

The article presents the development and construction of a magnetic filter based on the HGMS principle with permanent magnets. It is aimed especially at the assembly of the magnetic circuit using magnets from the material NdFeB. The way of the construction of large magnetic blocks, their magnetization and assembly are described. Further, it contains the measured values of magnetic induction in the middle of the air gap as a function of the width of this gap and of the height of the magnetic blocks in question, as well as the corresponding graphic representation. The high values of the magnetic induction obtained together with favourable price are sufficient reasons for the employment of this type of magnetic circuit in various applications

Sensorless Control of Interior Permanent Magnet Synchronous Motor in Low-Speed Region Using Novel Adaptive Filter

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Lisi Tian

2016-12-01

Full Text Available This paper presents a novel position and speed estimation method for low-speed sensorless control of interior permanent-magnet synchronous machines (IPMSMs. The parameter design of the position and speed estimator is based on the sampled current rather than the motor electrical parameters. The proposed method not only simplifies the parameter design, it enables the estimator to work normally even in the condition that the electrical parameters are uncertain or varied. The adaptive filters are adopted to extract the desired high frequency current. The structure and corresponding transfer function are analyzed. To address the shortage of insufficient stop-band attenuation, the structure of the adaptive filter is modified to provide suitable bandwidth and stop-band attenuation simultaneously. The effectiveness of the proposed sensorless control strategy has been verified by simulations and experiments.

SU-F-207-07: Dual-Energy Computed Tomography Detection Limit of Various Radiopaque Contrast Agents That Can Be Infused Within Absorbable Inferior Vena Cava Filters

Energy Technology Data Exchange (ETDEWEB)

Melancon, A; Jacobsen, M; Salatan, F; Jones, A; Cody, D; Nute, J; Melancon, M [U.T.M.D Anderson Cancer Center, Houston, TX (United States)

2015-06-15

Purpose: Absorbable IVC filters are shown to be safe and efficacious in preventing pulmonary embolism. These absorbable filters disappear from the body after their required duration, alleviating costly removal procedures and downstream complications. Monitoring the positioning and integrity of absorbable devices using dual-energy computed tomography (DECT) would improve treatment efficacy. The purpose of this study is to determine the limit of detection and the energy dependence of DECT for various contrast agents that may be infused within the IVC filters including gold nanoparticles (AuNP) having diameters of 2 and 4 nm. Methods: All imaging studies were performed on a GE Discovery CT750 system in Gemstone Spectral Imaging (GSI) mode. Plastic vials containing the contrast agent solutions of water and blood were placed in a water bath, and images were acquired with the GSI-5 preset. The images were reformatted into the coronal plane and 5mm diameter ROIs were placed within each solution on a GE Advantage Workstation. Monoenergetic reconstructions were generated from 40 – 140 keV. Results: Mass attenuation (contrast per unit density) for AuNPs was greater than iron, but less than barium and iodine. Contrast was 10.2 (± 3.6) HU for 4 nm AuNP at 0.72 mg/ml and 12.1 (± 4.2) for 2 nm AuNP at 0.31 mg/ml at 70 keV suggesting reasonable chance of visualization at these concentrations for 70 keV reconstruction. The contrast as a function of CT energy is similar in both water and blood. Iodine is most dependent, followed closely by barium and iron, and trailed by a large margin by the AuNP. This was unexpected given Au’s large atomic number and the predominance of photoelectric effect at low energy. Conclusion: Infusion of IVC filters with AuNP is feasible. Discrimination of AuNP-infused IVC filters from surrounding anatomy warrants further investigation.

Membranous IVC Obstruction Presenting with Antegrade/Retrograde Respiratory Flow in the Intrahepatic Segment in Doppler Imaging and Prostatic and Urethral Congestion

International Nuclear Information System (INIS)

Sood, Dinesh; Mistry, Kewal A.; Chadha, Veenal; Sharma, Sarthak; Morey, Parikshit D.; Suthar, Pokhraj P.; Patel, Dhruv G.

2015-01-01

Obstruction of the inferior vena cava (IVC) is infrequent, membranous obstruction of the IVC (MOIVC) being one of its rare causes. Early diagnosis is important, as it can lead to hepatic congestion, cirrhosis and Budd-Chiari syndrome (BCS) and can predispose to development of hepatocellular carcinoma (HCC) in severe cases. We report a case of membranous IVC obstruction at the junction of hepatic and suprahepatic segments in a young male with extensive collateralization and venous aneurysms. Unique findings involved antegrade and retrograde flow during respiration in the upper part of intrahepatic IVC proximal to a large collateral vein as well as prostatic and urethral congestion leading to intermittent urinary hesitancy, which have not yet been described in such cases. MOIVC is a rare cause of IVC obstruction with typical radiological features. Early diagnosis and management is required due to risk of cirrhosis and HCC. Antegrade and retrograde flow may be seen in incomplete MOIVC above the level of a large collateral vein and it may lead to prostatic and urethral congestion

Computational Modeling of Blood Flow in the TrapEase Inferior Vena Cava Filter

Energy Technology Data Exchange (ETDEWEB)

Singer, M A; Henshaw, W D; Wang, S L

2008-02-04

To evaluate the flow hemodynamics of the TrapEase vena cava filter using three dimensional computational fluid dynamics, including simulated thrombi of multiple shapes, sizes, and trapping positions. The study was performed to identify potential areas of recirculation and stagnation and areas in which trapped thrombi may influence intrafilter thrombosis. Computer models of the TrapEase filter, thrombi (volumes ranging from 0.25mL to 2mL, 3 different shapes), and a 23mm diameter cava were constructed. The hemodynamics of steady-state flow at Reynolds number 600 was examined for the unoccluded and partially occluded filter. Axial velocity contours and wall shear stresses were computed. Flow in the unoccluded TrapEase filter experienced minimal disruption, except near the superior and inferior tips where low velocity flow was observed. For spherical thrombi in the superior trapping position, stagnant and recirculating flow was observed downstream of the thrombus; the volume of stagnant flow and the peak wall shear stress increased monotonically with thrombus volume. For inferiorly trapped spherical thrombi, marked disruption to the flow was observed along the cava wall ipsilateral to the thrombus and in the interior of the filter. Spherically shaped thrombus produced a lower peak wall shear stress than conically shaped thrombus and a larger peak stress than ellipsoidal thrombus. We have designed and constructed a computer model of the flow hemodynamics of the TrapEase IVC filter with varying shapes, sizes, and positions of thrombi. The computer model offers several advantages over in vitro techniques including: improved resolution, ease of evaluating different thrombus sizes and shapes, and easy adaptation for new filter designs and flow parameters. Results from the model also support a previously reported finding from photochromic experiments that suggest the inferior trapping position of the TrapEase IVC filter leads to an intra-filter region of recirculating

Inferior vena cava filter penetration following Whipple surgical procedure causing ureteral injury.

Science.gov (United States)

Abdel-Aal, Ahmed Kamel; Ezzeldin, Islam B; Moustafa, Amr Soliman; Ertel, Nathan; Oser, Rachel

2015-12-01

We report a case of an indwelling inferior vena cava filter that penetrated the IVC wall after Whipple's pancreatico-duodenectomy procedure performed in a patient with ampullary carcinoma, resulting in right ureteral injury and obstruction with subsequent hydroureter and hydronephrosis. This was incidentally discovered on a computed tomography scan performed as routine follow up to evaluate the results of the surgery. We retrieved the inferior vena cava filter and placed a nephrostomy catheter to relieve the ureteral obstruction. Our case highlights the importance of careful inferior vena cava manipulation during abdominal surgery in the presence of an inferior vena cava filter, and the option of temporary removal of the filter to be placed again after surgery in order to avoid this complication, unless protection is required against clot migration during the surgical procedure.

It all unraveled from there: case report of a central venous catheter guidewire unraveling.

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Zerkle, Samuel; Emdadi, Vanessa; Mancinelli, Marc

2014-12-01

Inferior vena cava (IVC) filters can present challenges to emergency physicians in the process of central venous catheter (CVC) placement. A 68-year-old woman presented to the emergency department with severe shortness of breath and was intubated. A central line was placed after the intubation to facilitate peripheral access. A CVC guidewire unraveled during placement after getting caught on an IVC filter. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians should be aware of the complications that IVC filters can cause in the placement of CVCs. Imaging and identification of IVC filters beforehand will allow for proper planning of how to manage the case in which a filter catches on the guidewire. Simple anecdotal techniques, such as advancing the guidewire and spinning the guidewire between the fingers, can facilitate the removal of the guide wire from the IVC filter. Copyright © 2014 Elsevier Inc. All rights reserved.

Effect of Room Ventilation Rates in Rodent Rooms with Direct-Exhaust IVC Systems.

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Geertsema, Roger S; Lindsell, Claire E

2015-09-01

When IVC are directly exhausted from a rodent housing room, the air quality of the room can become independent of the intracage air quality and may reduce the need for high room ventilation rates. This study assessed the effect of decreasing the ventilation rate in rodent rooms using direct-exhaust IVC systems. The study was conducted over 16 wk and compared conditions in 8 rodent rooms that had ventilation rates of 5 to 6 air changes per hour (ACH) with those in rooms at 10 to 12 ACH. At the low ventilation rate, rooms had higher CO₂ concentrations, higher dew point temperature, and lower particulate levels and spent a greater percentage of time above the temperature set point than did rooms at the high rate. The levels of allergens and endotoxins in room air were the same regardless of the ventilation rate. Differences seen in parameters within cages at the 2 ventilation rates were operationally irrelevant. We detected no total volatile organic compounds in the room that were attributable to ammonia, regardless of the ventilation rate. Clearing the air of ethanol after a spill took longer at the low compared with high rate. However, ethanol clearance was faster at the low rate when the demand-control system was activated than at the high ventilation rate alone. Air quality in the room and in the cages were acceptable with room ventilation rates of 5 to 6 ACH in rodent rooms that use direct-exhaust IVC systems.

Temperature measurements in the TORMAC IV-c plasma

Energy Technology Data Exchange (ETDEWEB)

Greenwald, M.

1978-09-01

This thesis is divided into four main parts. The first is an introduction to the Tormac concept and a brief summary of the theoretical problems involved. The second part describes the experimental work with little detail. Both the construction and diagnostics are summarized. The third section is broken into two parts, a summary of the data taken on TORMAC IV-c and an explanation and discussion of the data. Finally, a number of lengthy appendices are included. These detail the construction and operation of the device and describe the principles and practice of the diagnostics employed.

Temperature measurements in the TORMAC IV-c plasma

International Nuclear Information System (INIS)

Greenwald, M.

1978-09-01

This thesis is divided into four main parts. The first is an introduction to the Tormac concept and a brief summary of the theoretical problems involved. The second part describes the experimental work with little detail. Both the construction and diagnostics are summarized. The third section is broken into two parts, a summary of the data taken on TORMAC IV-c and an explanation and discussion of the data. Finally, a number of lengthy appendices are included. These detail the construction and operation of the device and describe the principles and practice of the diagnostics employed

Retrievable Inferior Vena Cava Filters: Indications, Indwelling Time, Removal, Success and Complication Rates.

Science.gov (United States)

Tashbayev, Alisher; Belenky, Alexander; Litvin, Sergey; Knizhnik, Michael; Bachar, Gil N; Atar, Eli

2016-02-01

Various vena cava filters (VCF) are designed with the ability to be retrieved percutaneously. Yet, despite this option most of them remain in the inferior vena cava (IVC). To report our experience in the placement and retrieval of three different types of VCFs, and to compare the indications for their insertion and retrieval as reported in the literature. During a 5 year period three types of retrievable VCF (ALN, OptEase, and Celect) were inserted in 306 patients at the Rabin Medical Center (Beilinson and Hasharon hospitals). Indications, retrieval rates, median time to retrieval, success and complication rates were viewed and assessed in the three groups of filter types and were compared with the data of similar studies in the literature. Of the 306 VCFs inserted, 31 (10.1%) were retrieved with equal distribution in the three groups. In most patients the reason for filter insertion was venous thromboembolic events (VTE) and contraindications to anticoagulant therapy. Mean age was 68.38 ± 17.5 years (range 18-99) and was noted to be significantly higher compared to similar studies (53-56 years) (P < 0.0001). Multi-trauma patients were significantly older (71.11 ± 14.99 years) than post-pulmonary embolism patients (48.03 ± 20.98 years, P < 0.0001) and patients with preventive indication (26.00 ± 11.31, P < 0.0001). The mean indwelling time was 100.6 ± 103.399 days. Our results are comparable with the results of other studies, and there was no difference in percentage of retrieval or complications between patients in each of the three groups. In 1 of 10 patients filters should be removed after an average of 3.5 months. All three IVC filter types used are safe to insert and retrieve.

Pusher curving technique for preventing tilt of femoral Geunther Tulip inferior vena cava filter: in vitro study

International Nuclear Information System (INIS)

Xiao Liang; Shen Jing; Huang Desheng; Xu Ke

2011-01-01

Objective: To determine whether the adjustment of the pusher of GTF was useful to decrease the degree of tilting of the femoral Geunther Tulip filter (GTF) in an in vitro caval model. Methods: The caval model was constructed by placement of a 25 mm × 100 mm and two 10 mm × 200 mm Dacron graft inside a transparent bifurcate glass tube. The study consisted of two groups: left straight group (GLS) (n = 100) and left curved group (G LC ) (n=100). In the G LC , a 10° to 20° angle was curved on the introducer. The distance (D CH ) between the caval right wall and the hook was measured. The degree of tilting (DT) was classified into 5 grades and recorded. Before and after the GTF being released, the angle (A CM1,2 ) between the axis of IVC and the metal mount, the distance (D CM1 ) between the caval right wall and the metal mount, the angle (ACF) between the axis of IVC and the axis of the filter and the diameter of IVC (D IVC ) were measured. The data were analyzed with Chi-Square test, t test, rank sum. test and Pearson correlation test. Results: The degree of GTF tilting in each group revealed a divergent tendency. In group LC , the apex of the filter tended to be grade Ⅲ compared in group LS (χ 2 value 37.491, P LS and G LC were considered as statistical significance (16.60° vs. 3.05°, 20.60° vs. 3.50°, -3.90° vs. -0.40°, 2.98 mm vs. 10.40 mm, -10.95° vs. -0.485°, 13.17 mm vs. 10.06 mm, -1.70° vs. 0.70°, t or Z values -12.187, -12.188, -8.545, -51.834, -11.395, 9.562, -3.596, P CM1 and A CF , A CM1 - A CM2 and D CH1 - D CH2 in each group, respectively (r values 0.978, 0.344, 0.879, 0.627, P CH1 and A CF in each group, A CP and A CF in group LC (r values -0.974, -0.322, -0.702, P CM1 and A CF , A CM1 - A CM2 and D CH1 - D CH2 in each group, respectively (r values 0.978, 0.344, 0.879, 0.627, P CH1 and A CF in each group, A CP and A CF in group LC (r values -0.974, -0.322, -0.702, P<0.01). Conclusion: The technique of adjusting the orientation of filter

Permanent Magnet Synchronous Generator Driven Wind Energy Conversion System Based on Parallel Active Power Filter

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FERDI Brahim

2014-05-01

Full Text Available This paper proposes a novel application of the instantaneous P-Q theory in a wind energy conversion system (WECS. The proposed WECS is formed by permanent magnet synchronous generator (PMSG wind turbine system connected to the grid through parallel active power filter (PAPF. PAPF uses the generated wind energy to feed loads connected at the point of common coupling (PPC, compensates current harmonics and injects the excess of this energy into the grid using P-Q theory as control method. To demonstrate the feasibility and the performance of the proposed control scheme, simulation of this wind system has been realized using MATLAB/SIMULINK software. Simulation results show the accuracy and validity of the proposed control scheme for the PMSGPAPF system.

Management of IVC Injury: Repair or Ligation? A Propensity Score Matching Analysis Using the National Trauma Data Bank.

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Matsumoto, Shokei; Jung, Kyoungwon; Smith, Alan; Coimbra, Raul

2018-03-01

Ligation can be used as part of damage-control operations under critical conditions after IVC injury. Inferior vena cava ligation could potentially yield greater survival benefit compared with repair after injury. We hypothesized that ligation significantly improves outcomes compared with repair. The National Trauma Data Bank dataset for 2007-2014 was reviewed. Eligible patients included those sustaining IVC injury who underwent surgical ligation or repair. Data on demographics, outcomes, and complications were collected. Comparative analysis of demographic characteristics, complications and outcomes were performed. There were 4,865 patients identified in the National Trauma Data Bank with IVC injury. A total of 1,316 patients met inclusion criteria. Four hundred and forty-seven patients (34.0%) underwent ligation and 869 (66.0%) underwent repair. Before matching, the ligation group was sicker than the repair group and the in-hospital mortality was significantly higher in the ligation group (43.8% vs 36.2%; odds ratio [OR] 1.37; 95% CI 1.09 to 1.73). One to one propensity score matching generated 310 pairs. After propensity score matching, in-hospital mortality was similar (41.3% vs 39.0%; OR 1.10; 95% CI 0.80 to 1.52). However, IVC ligation was associated with significantly higher complication rates of extremity compartment syndrome (OR 5.23; 95% CI 1.50 to 18.24), pneumonia (OR 1.76; 95% CI 1.08 to 2.86), deep venous thrombosis (OR 2.83 95% CI 1.70 to 4.73), pulmonary embolism (OR 3.63; 95% CI 1.18 to 11.17), and longer hospital length of stay (17.0 days [interquartile range 1.0 to 35.0 days] vs 9.0 days [interquartile range 1.0 to 22.0 days]; p = 0.002). Inferior vena cava ligation is not superior to repair in terms of decreasing mortality in patients with IVC injury, but it is associated with higher complication rates and hospital LOS. Copyright © 2018 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Clinical significance of determination of serum collagen type IV (IV-C) and transforming growth factor beta1(TGF-β1) levels in patients with diabetic nephropathy

International Nuclear Information System (INIS)

Xie Hongfang; Peng Liang

2006-01-01

Objective: To investigate the clinical significance of determination of serum collagen type IV (IV-C) and transforming growth factor beta 1 (TGF-β 1 ) levels in patients with diabetic nephropathy. Methods: Serum IV-C levels ( with RIA) and TGF-β 1 levels (with ELISA) were determined in 30 controls and 105 patients with type II diabetis mellitus (45 with diabetic nephropathy and 60 without nephropathy). Results: The serum levels of IV-C and TGF-β 1 in diabetic patients with nephropathy were significantly higher than those in controls (P 0.05). Conclusion: Serum IV-C and TGF-β 1 , levels increased gradually as the diabetic nephropathy got more severe, they could be used as sensitive markers for early diagnosis of development of diabetic nephropathy. (authors)

Vena cava filter placement via the antecubital access: a report of 6 cases

International Nuclear Information System (INIS)

Yu Bo; Shi Weihao; He Qing; Wang Tieping; Wang Wei

2008-01-01

Objective: To study the methods and skill of vena cava filter placement via the antecubital access. Methods: Six patients with DVT (4 males and 2 females, mean age of 62) underwent vena cava filter placement via the antecubital access in Huashan Hospital from Oct. 2004 to May. 2006. The right basilic vein was punctured with the use of micropuncture technique. SNF(Simon nitinol filter, Bard)was inserted through its carrier into the 90-cm-long sheath. The filter was then deployed with a standard fashion in the IVC, 5 cm inferior to the renal vein. Results: The filter was once placed successfully in all six patients within average time of 25 min without complications, but with good healing, exclusion of bleeding and no phlebitis. The position of filter was accurate without deviation and no occurrence of pulmonary embolism. Conclusions: vena cava filter placement via antecubital access is easy, minimal invasive, no need of lying in bed postoperatively. It is beneficial for DVT patients as an alternative for the contra-indication to femoral venous access. (authors)

Caval filter implantation under MRI control - experimental in vitro and in vivo investigations

International Nuclear Information System (INIS)

Neuerburg, J.; Buecker, A.; Adam, G.; Leenen, M.; Guenther, R.W.; Hurtak, M.S.W.

1997-01-01

Purpose: An instrument has been developed for the introduction of caval filters which can be used with MRI; it has been investigated in in vitro and in in vivo experiments. Material and method: The ferromagnetic components of a commercially available instrument for the femoral introduction of the MR-eye TM Tulip IVC filter were changed for similar, non-ferromagnetic parts and the lock and dilator marked with dysprosium oxide rings. The instrument was used in a flow phantom and in animal experiments (two domestic pigs) in order to insert filters under MRI control on a 1.5 T Philips Gyroscan with integrated mobile digital subtraction angiography. Results: Both in vitro and in vivo, the introducer, catheter and caval filter could be identified by MRI and positioned under MRI control. The position of the filter as indicated by MRI corresponded with radiological and macroscopic findings in all cases (5 phantoms, 2 pigs). Conclusion: The early experimental results indicate that percutaneous introduction of caval filters with placement under MRI control is possible. (orig.) [de

A marked proportional rise in IVC aldosterone following cosyntropin administration during AVS is a signal to the presence of adrenal hyperplasia in primary aldosteronism.

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Kline, G A; Pasieka, J L; Harvey, A; So, B; Dias, V C

2014-05-01

We hypothesized aldosteronoma responsiveness to cosyntropin may be a characterizing feature that could be determined in addition to standard adrenal vein sampling (AVS) data. We reviewed an AVS database from June 2005 to October 2011 including 65 patients with confirmed primary aldosteronism (PA) who underwent AVS and, if applicable, unilateral adrenalectomy. Patients were divided into confirmed lateralized and non-lateralized groups and subgrouped by histology. Plasma aldosterone in inferior vena cava (IVC) pre- and post-cosyntropin infusion during AVS was measured. Peak aldosterone and proportional change was compared between groups. Baseline and peak IVC aldosterone was higher in lateralized patients but incremental aldosterone rise was much greater in subjects with bilateral hyperplasia. From receiver operator characteristics (ROC) analysis, the optimized diagnostic cut point of peak IVC aldosterone of >649 pmol l(-1) would have a sensitivity of 94% for surgical disease although specificity of just 59%. A 250% increase in IVC aldosterone following cosyntropin would be specific enough to exclude 87% of surgical/lateralized disease. These diagnostic capabilities are similar to other results with non-AVS tests performed for diagnosis of lateralization. Although not specific enough to replace standard AVS interpretation, a marked IVC aldosterone increase after cosyntropin during AVS is a useful additional test to diagnose non-lateralizing forms of PA. Such a calculation requires no additional expense or tests.

Modeling Flow Past a Tilted Vena Cava Filter

Energy Technology Data Exchange (ETDEWEB)

Singer, M A; Wang, S L

2009-06-29

Inferior vena cava filters are medical devices used to prevent pulmonary embolism (PE) from deep vein thrombosis. In particular, retrievable filters are well-suited for patients who are unresponsive to anticoagulation therapy and whose risk of PE decreased with time. The goal of this work is to use computational fluid dynamics to evaluate the flow past an unoccluded and partially occluded Celect inferior vena cava filter. In particular, the hemodynamic response to thrombus volume and filter tilt is examined, and the results are compared with flow conditions that are known to be thrombogenic. A computer model of the filter inside a model vena cava is constructed using high resolution digital photographs and methods of computer aided design. The models are parameterized using the Overture software framework, and a collection of overlapping grids is constructed to discretize the flow domain. The incompressible Navier-Stokes equations are solved, and the characteristics of the flow (i.e., velocity contours and wall shear stresses) are computed. The volume of stagnant and recirculating flow increases with thrombus volume. In addition, as the filter increases tilt, the cava wall adjacent to the tilted filter is subjected to low velocity flow that gives rise to regions of low wall shear stress. The results demonstrate the ease of IVC filter modeling with the Overture software framework. Flow conditions caused by the tilted Celect filter may elevate the risk of intrafilter thrombosis and facilitate vascular remodeling. This latter condition also increases the risk of penetration and potential incorporation of the hook of the filter into the vena caval wall, thereby complicating filter retrieval. Consequently, severe tilt at the time of filter deployment may warrant early clinical intervention.

A new device for the prevention of pulmonary embolism in critically ill patients: Results of the European Angel Catheter Registry.

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Taccone, Fabio S; Bunker, Nicholas; Waldmann, Carl; De Backer, Daniel; Brohi, Karim; Jones, Robert G; Vincent, Jean-Louis

2015-09-01

Pulmonary embolism (PE) is a potentially life-threatening complication of critical illness. In trauma and neurosurgical patients with contraindications to anticoagulation, inferior vena cava (IVC) filters have been used to prevent PE, but their associated long-term complication rates and difficulties associated with filter removal have limited their use. The Angel catheter is a temporary device, which combined an IVC filter with a triple-lumen central venous catheter (IVC filter-catheter) and is intended for bedside placement and removal when no longer indicated. This study presents data from a European Registry of 60 critically ill patients in whom the IVC filter-catheter was used to prevent PE. The patients were all at high risk of PE development or recurrence and had contraindications to anticoagulation. The primary end points of this study were to evaluate the safety (in particular, the presence of infectious or thrombotic events) and effectiveness (the numbers of PEs and averted PEs) of the IVC filter-catheter. The main diagnosis before catheter insertion was major trauma in 33 patients (55%), intracerebral hemorrhage or stroke in 9 (15%), a venous thromboembolic event in 9 (15%), and active bleeding in 6 (10%). The IVC filter-catheter was placed as prophylaxis in 51 patients (85%) and as treatment in the 9 patients (15%) with venous thromboembolic event. The devices were inserted at the bedside without fluoroscopic guidance in 54 patients (90%) and within a median of 4 days after hospital admission. They were left in place for a mean of 6 days (4-8 days). One patient developed a PE, without hemodynamic compromise; two PEs were averted. No serious adverse events were reported. Early bedside placement of an IVC filter-catheter is possible, and our results suggest that this is a safe, effective alternative to short-term PE prophylaxis for high-risk patients with contraindications to anticoagulation. Therapeutic study, level V.

Optease Vena Cava Filter Optimal Indwelling Time and Retrievability

International Nuclear Information System (INIS)

Rimon, Uri; Bensaid, Paul; Golan, Gil; Garniek, Alexander; Khaitovich, Boris; Dotan, Zohar; Konen, Eli

2011-01-01

The purpose of this study was to assess the indwelling time and retrievability of the Optease IVC filter. Between 2002 and 2009, a total of 811 Optease filters were inserted: 382 for prophylaxis in multitrauma patients and 429 for patients with venous thromboembolic (VTE) disease. In 139 patients [97 men and 42 women; mean age, 36 (range, 17–82) years], filter retrieval was attempted. They were divided into two groups to compare change in retrieval policy during the years: group A, 60 patients with filter retrievals performed before December 31 2006; and group B, 79 patients with filter retrievals from January 2007 to October 2009. A total of 128 filters were successfully removed (57 in group A, and 71 in group B). The mean filter indwelling time in the study group was 25 (range, 3–122) days. In group A the mean indwelling time was 18 (range, 7–55) days and in group B 31 days (range, 8–122). There were 11 retrieval failures: 4 for inability to engage the filter hook and 7 for inability to sheathe the filter due to intimal overgrowth. The mean indwelling time of group A retrieval failures was 16 (range, 15–18) days and in group B 54 (range, 17–122) days. Mean fluoroscopy time for successful retrieval was 3.5 (range, 1–16.6) min and for retrieval failures 25.2 (range, 7.2–62) min. Attempts to retrieve the Optease filter can be performed up to 60 days, but more failures will be encountered with this approach.

The effect of IVM and IVC media on in vitro development of bovine embryos

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E.T Mergawati

2000-12-01

Full Text Available The purpose of this study was to examine the effect of medium combination of IVM and IVC on the in vitro development of bovine embryos. The study involved 4 groups in a 2 (IVM medium x 2 (IVC medium factorial in a randomized block design. Each group was replicated for 5 times. The treatments were as follows: TCM-199/CR1aa (T1; TCM-199/SOF (T2; B- 199/CR1aa (T3 and B-199/SOF (T4. Oocytes were aspirated from ovaries collected at local abattoirs using aspiration medium of PBS supplemented with 3% FCS and 0.1% Penicillin and Streptomycin. The oocytes were matured in medium of TCM-199 or B-199 supplemented with 10% FCS, hormones: 10μg/ml FSH+ 10μg/ml hCG+ 1μg/ml Estradiol. Maturation was maintained at 37oC for 22 hours in 5% CO2 incubator with high humidity. A method of BRACKETT & Oliphant (BO was used to fertilize the matured oocytes. The fertilization was incubated for 7 hours in the 5% CO2 incubator. Two culture media of CR1aa or SOF/AA/BSA were used to develop the fertilized oocytes undergo to morula and blastocyst embryos. The findings showed that the proportion of oocytes cleaved and formation of blastocysts were affected significantly by a combination of IVM and IVC media (P<0.05. A combination of B-199/SOF (T4 resulted in a higher blastocyst rate (32% than others (T3= 29%; T2=T1= 23%. This study suggests that either SOF/AA/BSA or CR1aa has similar competence in development of bovine embryos in vitro.

The high-risk polytrauma patient and inferior vena cava filter use.

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Berber, Onur; Vasireddy, Aswin; Nzeako, Obi; Tavakkolizadeh, Adel

2017-07-01

The aim of this study was to assess the impact on practice of vena cava filter insertion guidelines (Eastern Association for the Surgery of Trauma: practice management guidelines). The study was performed at a level 1 trauma centre with data from the 'Trauma Audit and Research Network' cross-referenced to hospital data. A total of 1138 specific 'high-risk' major trauma patients were identified over a 6-year period. The mean age was 46 years (18-102) and the male to female ratio was 3.3:1. The average Injury Severity Score was 23.6 (4-75). The overall DVT rate was 2.6% and the PE rate was 1.8%. A retrievable IVC filter was inserted in 42 cases (3.8%). The filter retrieval rate was 23.8% at a mean of 68.5days (4-107). Only one complication was reported of a breakthrough PE despite filter. Applying the EAST guidelines to this cohort would have suggested filter insertion in 279 (24.6%) cases. The kappa concordance value between observed practice and the 'EAST filter group' was 0.103 (poor). The PE rate in the 'EAST filter group' was 2.2% vs 1.6% in the 'no filter group' (p=0.601, no statistical difference) and the observed odds ratio was 0.814 (95% CI 0.413, 1.602). The EAST guidelines are useful but may be overestimating the need for filter insertion. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dynamic Analysis of Permanent Magnet Synchronous Generator with Power Electronics

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OZCIRA, S.

2010-05-01

Full Text Available Permanent magnet DC motor-generators (PMDC, PMSG have been widely used in industrial and energy sectors recently. Power control of these systems can be achieved by controlling the output voltage. In this study, PMDC-PMSG systems are mathematically modeled and simulated in MATLAB and Simulink software. Then the results are discussed. A low power permanent magnet synchronous generator is driven by a permanent magnet DC motor and the output voltage is controlled by a frequency cycle-converter. The output of a half-wave uncontrolled rectifier is applied to an SPWM inverter and the power is supplied to a 300V, 50Hz load. The load which is connected to an LC filter is modeled by state-space equations. LC filter is utilized in order to suppress the voltage oscillations at the inverter output.

Backflushable filter insert

International Nuclear Information System (INIS)

Keith, R.C.; Vandenberg, T.; Randolph, M.C.; Lewis, T.B.; Gillis, P.J. Jr.

1988-01-01

Filter elements are mounted on a tube plate beneath an accumulator chamber whose wall is extended by skirt and flange to form a closure for the top of pressure vessel. The accumulator chamber is annular around a central pipe which serves as the outlet for filtered water passing from the filter elements. The chamber contains filtered compressed air from supply. Periodically the filtration of water is stopped and vessel is drained. Then a valve is opened, allowing the accumulated air to flow from chamber up a pipe and down pipe, pushing the filtered water from pipe back through the filter elements to clean them. The accumulator chamber is so proportioned, relative to the volume of the system communicating therewith during backflushing, that the equilibrium pressure during backflushing cannot exceed the pressure rating of the vessel. However a line monitors the pressure at the top of the vessel, and if it rises too far a bleed valve is automatically opened to depressurise the system. The chamber is intended to replace the lid of an existing vessel to convert a filter using filter aid to one using permanent filter elements. (author)

Beta-spectrometer with magnetic filter of mini orange type

International Nuclear Information System (INIS)

Gorozhankin, V.M.; Gromov, K.Ya.; Kalinnikov, V.G.; Sereeter, Z.; Fominykh, V.I.; Malikov, Sh.R.; Yuldashev, M.B.

1997-01-01

At the ISOL facility YASNAPP-2 a β-spectrometer with a magnetic filter of the miniorange type is constructed to measure γ-ray internal conversion coefficients. The magnetic filter of the mini orange type is an assemblage of permanent magnets creating a toroidal magnetic field perpendicular to the electron trajectories from the source to the Si(Li) detector. The chosen profile of the permanent magnets allowed electron registration in the defined energy energy interval with some transmission increase. There are two sets of permanent magnets of the different thickness. Varying the type and number of permanent magnets one can set the detected electron energy intervals in a 50-2500 keV range. The efficiency of the spectrometer was investigated for different assemblages of the mini orange magnet. The facility can be used for the e-γ coincidence investigation. (A.A.D.)

Limitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters

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Robinson RA

2013-05-01

Full Text Available Ronald A Robinson, Luke H Herbertson, Srilekha Sarkar Das, Richard A Malinauskas, William F Pritchard, Laurence W GrossmanOffice of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD, USAAbstract: The purpose of this study was first to evaluate the clot capture efficiency and capture location of six currently-marketed vena cava filters in a physiological venous flow loop, using synthetic polyacrylamide hydrogel clots, which were intended to simulate actual blood clots. After observing a measured anomaly for one of the test filters, we redirected the focus of the study to identify the cause of poor clot capture performance for large synthetic hydrogel clots. We hypothesized that the uncharacteristic low clot capture efficiency observed when testing the outlying filter can be attributed to the inadvertent use of dense, stiff synthetic hydrogel clots, and not as a result of the filter design or filter orientation. To study this issue, sheep blood clots and polyacrylamide (PA synthetic clots were injected into a mock venous flow loop containing a clinical inferior vena cava (IVC filter, and their captures were observed. Testing was performed with clots of various diameters (3.2, 4.8, and 6.4 mm, length-to-diameter ratios (1:1, 3:1, 10:1, and stiffness. By adjusting the chemical formulation, PA clots were fabricated to be soft, moderately stiff, or stiff with elastic moduli of 805 ± 2, 1696 ± 10 and 3295 ± 37 Pa, respectively. In comparison, the elastic moduli for freshly prepared sheep blood clots were 1690 ± 360 Pa. The outlying filter had a design that was characterized by peripheral gaps (up to 14 mm between its wire struts. While a low clot capture rate was observed using large, stiff synthetic clots, the filter effectively captured similarly sized sheep blood clots and soft PA clots. Because the stiffer synthetic clots remained straight when approaching the

A case of huge colon carcinoma and right renal angiomyolipoma accompanied by proximal deep venous thrombosis, pulmonary embolism and tumor thrombus in the renal vein.

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Ban, Daisuke; Yamamoto, Seiichiro; Kuno, Hirofumi; Fujimoto, Hiroyuki; Fujita, Shin; Akasu, Takayuki; Moriya, Yoshihiro

2008-10-01

A preoperative inferior vena cava (IVC) filter is reported to be effective in surgical cases with proximal deep venous thrombosis (DVT) or in which pulmonary embolism (PE) has already developed, and considered to be at high risk of developing secondary fatal PE during or after surgery. However, guidelines for using an IVC filter have yet to be established. The patient in the present report had two huge tumors, ascending colon cancer and renal angiomyolipoma, which occupied the entire right half of the abdomen, coexisting PE, DVT and tumor thrombus in the right renal vein. Secondary PE is fatal in the perioperative period, therefore, the vena cava filters were preoperatively inserted into the supra- and the infrarenal IVC. We successfully removed the tumors without complications. The patient is alive without tumor recurrence and PE or recurrent DVT 1 year and 6 months after surgery. The coexistence of two huge abdominal tumors as potential causes of PE and DVT is extremely rare, and we could have safely undergone the operation, using two vena cava filters in the supra- and infrarenal IVC.

An Application of the PMI Model at the Project Level Evaluation of ESEA Title IV-C Projects.

Science.gov (United States)

McBeath, Marcia

All of the papers presented as part of a symposium concerned the application of the Planning, Monitoring, and Implementation Model (PMI) to the evaluation of the District of Columbia Public Schools' programs supported by the Elementary Secondary Education Act (ESEA) Title IV-C. PMI was developed to provide a model for systematic evaluation of…

Management of acute lower extremity deep venous thrombosis in a patient with duplicated inferior vena cava and contraindication to anticoagulation: case and review of the literature.

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Patel, Shrinil; Cheema, Anmol; Karawadia, Tejas; Carson, Michael

2018-06-04

Duplication of the inferior vena cava (DIVC) is an uncommon embryological anatomic phenomenon.We report a 63-year-old woman with extensive right leg deep vein thrombosis who required an IVC filter due to contraindications for anticoagulation, but was found to have DIVC which required the placement of two IVC filters with good result. This report will review and summarise past reports of DIVC management to provide a guide for future clinicians, and review the embryological development, diagnosis and IVC filter placement options as they are based on the type of anatomic malformation encountered. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Density and magnetic field measurements in the Tormac IV-c plasma

International Nuclear Information System (INIS)

Coonrod, J.W. Jr.

1978-01-01

Tormac is a concept for magnetically confining a high-β fusion plasma in a toroidal, stuffed line cusp. A Tormac plasma has two regions: an interior confined on the closed toroidal field lines of the stuffing field, and an exterior sheath on open, cusped field lines. The interior plasma gives the device a longer confinement time than a standard mirror, while the favorable curvature of the cusp fields allow the plasma to be stable at higher values of β (the ratio of the plasma pressure to magnetic pressure) than a totally closed configuration like Tokamak. This thesis describes the design, construction and operation of Tormac IV-c, and reports on the results, with emphasis on describing the behavior of the density compression and field penetration

Clinical review: inferior vena cava filters in the age of patient-centered outcomes.

Science.gov (United States)

Wang, Stephen L; Lloyd, Allen J

2013-11-01

Inferior vena cava filter (IVCF) use continues to increase in the United States (US) despite questionable clinical benefit and increasing concerns over long-term complications. For this review we comprehensively examine the randomized, prospective data on IVC filter efficacy, compare relative rates of IVCF placement in the US and Europe, compare commonly considered guidelines for IVCF indications, and the current data on IVCF complications. Searches of MEDLINE and Cochrane databases were conducted for randomized prospective IVCF studies. Only three randomized prospective studies for IVCFs were identified. Commonly cited IVCF guidelines were reviewed with attention to their evolution over time. No evidence has shown a survival benefit with IVCF use. Despite this, continued rising utilization, especially for primary prophylactic indications, is concerning, given increasing evidence of long-term filter-related complications. This is particularly noted in the US where IVCF placements for 2012 are projected to be 25 times that of an equivalent population in Europe (224,700 versus 9,070). Pending much-needed randomized controlled trials that also evaluate long-term safety, we support the more stringent American College of Chest Physicians (ACCP) guidelines for IVCF placement indications and advocate a close, structured follow-up of retrievable IVCFs to improve filter retrieval rates.

Murine norovirus detection in the exhaust air of IVCs is more sensitive than serological analysis of soiled bedding sentinels.

Science.gov (United States)

Zorn, Julia; Ritter, Bärbel; Miller, Manuel; Kraus, Monika; Northrup, Emily; Brielmeier, Markus

2017-06-01

One limitation to housing rodents in individually ventilated cages (IVCs) is the ineffectiveness of traditional health monitoring programs that test soiled bedding sentinels every quarter. Aerogen transmission does not occur with this method. Moreover, the transmission of numerous pathogens in bedding is uncertain, and sentinel susceptibility to various pathogens varies. A novel method using particle collection from samples of exhaust air was developed in this study which was also systematically compared with routine health monitoring using soiled bedding sentinels. We used our method to screen these samples for the presence of murine norovirus (MNV), a mouse pathogen highly prevalent in laboratory animal facilities. Exhaust air particles from prefilters of IVC racks with known MNV prevalence were tested by quantitative reverse transcription polymerase chain reaction (RT-qPCR). MNV was detected in exhaust air as early as one week with one MNV-positive cage per rack, while sentinels discharged MNV RNA without seroconverting. MNV was reliably and repeatedly detected in particles collected from samples of exhaust air in all seven of the three-month sampling rounds, with increasing MNV prevalence, while sentinels only seroconverted in one round. Under field conditions, routine soiled bedding sentinel health monitoring in our animal facility failed to identify 67% ( n = 85) of positive samples by RT-qPCR of exhaust air particles. Thus, this method proved to be highly sensitive and superior to soiled bedding sentinels in the reliable detection of MNV. These results represent a major breakthrough in hygiene monitoring of rodent IVC systems and contribute to the 3R principles by reducing the number of animals used and by improving experimental conditions.

Melanotic Xp11 Translocation Renal Cancer Managed With Radical Nephrectomy and IVC Tumor Thrombectomy

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Iyad S. Khourdaji

2017-01-01

Full Text Available Melanotic Xp11 translocation renal cancer is a rarely observed neoplasm primarily affecting adolescents and young adults. Given the paucity of data describing this malignancy, its natural history and subsequent long-term management are not well understood. We report a case of melanotic Xp11 translocation with tumor thrombus extension managed with radical nephrectomy and inferior vena cava (IVC tumor thrombectomy. To our knowledge, this is the first case report to describe use of conventional tumor thrombectomy techniques in a patient with melanotic Xp11 translocation renal cancer.

Thromboembolic Risk of Endovascular Intervention for Lower Extremity Deep Venous Thrombosis.

Science.gov (United States)

Lindsey, Philip; Echeverria, Angela; Poi, Mun J; Matos, Jesus; Bechara, Carlos F; Cheung, Mathew; Lin, Peter H

2018-05-01

This study evaluated the risk of thromboembolism during endovascular interventions in patients with symptomatic lower extremity deep vein thrombosis (DVT) METHODS: Clinical records of all patients who underwent endovascular interventions for symptomatic lower extremity DVT from 2001 to 2017 were retrospectively analyzed using a prospectively maintained database. Only patients who received an inferior vena cava (IVC) filter were included in the analysis. Trapped intrafilter thrombus was assessed for procedure-related thromboembolism. Clinical outcomes of thrombus management and thromboembolism risk were analyzed. A total 172 patients (mean age 57.4 years, 98 females) who underwent 174 endovascular DVT interventions were included in the analysis. Treatment strategies included thrombolytic therapy (64%), mechanical thrombectomy (n = 86%), pharmacomechanical thrombolysis (51%), balloon angioplasty (98%), and stent placement (28%). Thrombectomy device used included AngioJet (56%), Trellis (19%), and Aspire (11%). Trapped IVC filter thrombus was identified in 58 patients (38%) based on the IVC venogram. No patient developed clinically evident pulmonary embolism (PE). IVC filter retrieval was performed in 98 patients (56%, mean 11.8 months after implantation). Multivariate analysis showed that iliac vein occlusion (P = 0.04) was predictive for procedure-related thromboembolism. Iliac vein thrombotic occlusion is associated with an increased thromboembolic risk in DVT intervention. Retrievable IVC filter should be considered when performing percutaneous thrombectomy in patients with iliac venous occlusion to prevent PE. Copyright © 2017 Elsevier Inc. All rights reserved.

Optimal design of active EMC filters

Science.gov (United States)

Chand, B.; Kut, T.; Dickmann, S.

2013-07-01

A recent trend in automotive industry is adding electrical drive systems to conventional drives. The electrification allows an expansion of energy sources and provides great opportunities for environmental friendly mobility. The electrical powertrain and its components can also cause disturbances which couple into nearby electronic control units and communication cables. Therefore the communication can be degraded or even permanently disrupted. To minimize these interferences, different approaches are possible. One possibility is to use EMC filters. However, the diversity of filters is very large and the determination of an appropriate filter for each application is time-consuming. Therefore, the filter design is determined by using a simulation tool including an effective optimization algorithm. This method leads to improvements in terms of weight, volume and cost.

Evaluation of prototype electrofibrous filters for nuclear ventilation ducts

International Nuclear Information System (INIS)

Bergman, W.; Kuhl, W.D.; Biermann, A.H.; Johnson, J.S.; Lum, B.Y.

1983-01-01

Two prototype electrofibrous filters were designed, built and evaluated in laboratory tests and in field installations. These prototypes were designed for use in nuclear ventilation ducts as prefilters to HEPA filters. One prototype is designed to be a permanent component of the ventilation system while the other is a disposable unit. The disposable electrofibrous prefilter was installed in the exhaust stream of a glove box in which barrels of uranium turnings are burned. Preliminary tests show the disposable prefilter is effectively prolonging the HEPA filter life

Evaluation of prototype electrofibrous filters for nuclear-ventilation ducts

International Nuclear Information System (INIS)

Bergman, W.; Kuhl, W.D.; Biermann, A.H.; Johnson, J.S.; Lum, B.Y.

1982-01-01

Two prototypes electrofibrous filters were designed, built and evaluated in laboratory tests and in field installations. These prototypes were designed for use in nuclear ventilation ducts as prefilters to HEPA filters. One prototype is designed to be a permanent component of the ventilation system while the other is a disposable unit. The disposable electrofibrous prefilter was installed in the exhaust stream of a glove box in which barrels of uranium turnings are burned. Preliminary tests show the disposable prefilter is effectively prolonging the HEPA filter life

Spectral filtering for plant production

Energy Technology Data Exchange (ETDEWEB)

Young, R.E.; McMahon, M.J.; Rajapakse, N.C.; Becoteau, D.R.

1994-12-31

Research to date suggests that spectral filtering can be an effective alternative to chemical growth regulators for altering plant development. If properly implemented, it can be nonchemical and environmentally friendly. The aqueous CuSO{sub 4}, and CuCl{sub 2} solutions in channelled plastic panels have been shown to be effective filters, but they can be highly toxic if the solutions contact plants. Some studies suggest that spectral filtration limited to short EOD intervals can also alter plant development. Future research should be directed toward confirmation of the influence of spectral filters and exposure times on a broader range of plant species and cultivars. Efforts should also be made to identify non-noxious alternatives to aqueous copper solutions and/or to incorporate these chemicals permanently into plastic films and panels that can be used in greenhouse construction. It would also be informative to study the impacts of spectral filters on insect and microbal populations in plant growth facilities. The economic impacts of spectral filtering techniques should be assessed for each delivery methodology.

Sensorless control of interior permanent-magnet synchronous motors with compressor load

DEFF Research Database (Denmark)

Huang, Shoudao; Gao, Jian; Xiao, Lei

2013-01-01

This paper analyzes the mathematical model of the interior permanent-magnet synchronous motors (IPMSM). Through the mathematical deformation, the paper proposes the new sensorless method based on sliding mode observer for a IPMSM. The model is only associated with the q-axis inductance, and without...... the d-axis inductance. Dual filter is set series to extract the electromotive force information, and then filter phase shift is measured real-time at different speeds for angle compensation. An I-F strategy is adopted to start the IPMSM with compressor load. Finally, the experimental proves the validity...

Field evaluation of prototype electrofibrous filters

International Nuclear Information System (INIS)

Kuhl, W.D.; Bergman, W.; Biermann, A.H.; Lum, B.Y.

1982-01-01

New prototype electrofibrous filters were designed, built and evaluated in laboratory tests and in field installations. Two prototypes were designed for use in nuclear ventilation ducts as prefilters to HEPA filters. One prototype is designed to be a permanent component of the ventilation system while the other is a disposable unit. The disposable electrofibrous prefilter was installed in the exhaust stream of a glove box in which barrels of uranium turnings are burned. Preliminary tests show the disposal prefilter is effectively prolonging the HEPA filter life. An earlier prototype of the rolling prefilter was upgraded to meet the increased requirements for installation in a nuclear facility. This upgraded prototype was evaluated in the fire test facility at LLNL and shown to be effective in protecting HEPA filters from plugging under the most severe smoke conditions. The last prototype described in this report is a recirculating air filter. After demonstrating a high performance in laboratory tests the unit was shipped to Savannah River where it is awaiting installation in a Pu fuel fabrication facility. An analysis of the particulate problem in Savannah River indicates that four recirculating air filter will save $172,000 per year in maintenance costs

Porous Metal Filters for Gas and Liquid Applications in the Nuclear Industry

International Nuclear Information System (INIS)

Kenneth, Rubow

2009-01-01

Sintered metal media are ideally suited for use in the most demanding industrial applications where long life is required and often other media are not cost-effective solution. As examples, filtration technology utilizing sintered metal media provides excellent performance in numerous liquid/solids and gas/solid separation applications found in the handling and processing of fluids containing radioactive materials. Many types of filter media, ranging from single use (disposable) to semi-permanent, are utilized today for separation of particulate matter. However, semi-permanent media are usually cleanable, either on or off-line, and are intended for sustainable, often multi-year, operating life in harsh environments. These harsh environments, which may involve corrosive fluids, high temperatures, high pressures or pressure spikes, often requiring continuous filtration service, are ideally suited for all-metal filtration systems employing semi-permanent sintered metal media. Sintered metal media, usually fabricated into tubular metal elements, have proven high particle removal efficiency and demonstrated reliability that uniquely afford excellent performance for demanding liquid/solids and gas/solids separation processes. The filter element and, in certain cases, the entire filter are weldable; therefore, the inherent sealing eliminates the need for potentially problematic seals. These media provide a positive barrier to ensure particulate removal to protect downstream equipment, for product separation, and/or to meet health, safety and environmental regulations. Typical applications for sintered metal media include: 1) gas and liquid filter systems used in various nuclear and radioactive waste processing applications, 2) an all-metal High Efficiency Particulate Air (HEPA) filter developed under Department of Energy (DOE) funding as an alternative to traditional HEPA filters fabricated with conventional glass fibers used on High Level Waste (HLW) tank ventilation

Rise and subsequent decline of community-associated methicillin resistant Staphylococcus aureus ST30-IVc in Copenhagen, Denmark through an effective search and destroy policy

DEFF Research Database (Denmark)

Bartels, M D; Kristoffersen, K; Boye, K

2010-01-01

was insufficient and at least one person in each household was treated with systemic antibiotics. All families were MRSA negative at 1-year follow-up. The CA-MRSA clone ST30-IVc has been imported to Copenhagen, Denmark, primarily from the Philippines, and has spread through close contacts and in kindergartens...... to the Philippines. Household members were screened for MRSA and all members of families with MRSA carriers were offered treatment of the carrier state and were followed for 1 year. MRSA carriers were found in seven of 16 households and transmission occurred among close contacts and in kindergartens. Five days of ET....... Treatment of MRSA carriers was difficult and required many resources, but the clone was eventually successfully eliminated. The import of ST30-IVc to Denmark will continue, but the spread of the clone in Denmark can be kept to a minimum by direct intervention in the affected families....

OptEase and TrapEase Vena Cava Filters: A Single-Center Experience in 258 Patients

International Nuclear Information System (INIS)

Onat, Levent; Ganiyusufoglu, Ali Kursat; Mutlu, Ayhan; Sirvanci, Mustafa; Duran, Cihan; Ulusoy, Onur Levent; Hamzaoglu, Azmi

2009-01-01

We aimed to evaluate the efficacy and safety of the OptEase and TrapEase (both from Cordis, Roden, Netherlands) vena cava filters in the prevention of pulmonary embolism (PE). Between May 2004 and December 2008, OptEase (permanent/retrievable; n = 228) or TrapEase (permanent; n = 30) vena cava filters were placed in 258 patients (160 female and 98 male; mean age 62 years [range 22 to 97]). Indications were as follows: prophylaxis for PE (n = 239), contraindication for anticoagulation in the presence of PE or DVT (n = 10), and development of PE or DVT despite anticoagulation (n = 9). Medical records were retrospectively reviewed for indications, clinical results, and procedure-related complications during placement and retrieval. Clinical PE did not develop in any of the patients. However, radiologic signs of segmental PE were seen in 6 of 66 patients with follow-up imaging data. Migration or fracture of the filter or cava perforation was not seen in any of the patients. Except for a single case of asymptomatic total cava thrombosis, no thrombotic occlusion was observed. One hundred forty-one patients were scheduled to undergo filter removal; however, 17 of them were not suitable for such based on venography evaluation. Removal was attempted in 124 patients and was successful in 115 of these (mean duration of retention 11 days [range 4 to 23]). Nine filters could not be removed. Permanent/retrievable vena cava filters are safe and effective devices for PE prophylaxis and for the management of venous thromboembolism by providing the option to be left in place.

Type-IVC Secretion System: A Novel Subclass of Type IV Secretion System (T4SS) Common Existing in Gram-Positive Genus Streptococcus

Science.gov (United States)

Chen, Chen; Gao, George F.

2012-01-01

A growing number of pathogens are being found to possess specialized secretion systems which they use in various ways to subvert host defenses. Type IV secretion system (T4SS) is one of versatile secretion systems essential for the virulence and even survival of some bacteria species, and they enable the secretion of protein and DNA substrates across the cell envelope. T4SS was once believed to be present only in Gram-negative bacteria. In this study, we present evidence of a new subclass of T4SS, Type-IVC secretion system and indicate its common existence in the Gram-positive bacterial genus Streptococcus. We further identified that VirB1, VirB4, VirB6 and VirD4 are the minimal key components of this system. Using genome comparisons and evolutionary relationship analysis, we proposed that Type-IVC secretion system is movable via transposon factors and mediates the conjugative transfer of DNA, enhances bacterial pathogenicity, and could cause large-scale outbreaks of infections in humans. PMID:23056296

Charcoal filter testing

Energy Technology Data Exchange (ETDEWEB)

Lyons, J. [Nuclear Regulatory Commission, Washington, DC (United States)

1997-08-01

In this very brief, informal presentation, a representative of the US Nuclear Regulatory Commission outlines some problems with charcoal filter testing procedures and actions being taken to correct the problems. Two primary concerns are addressed: (1) the process to find the test method is confusing, and (2) the requirements of the reference test procedures result in condensation on the charcoal and causes the test to fail. To address these problems, emergency technical specifications were processed for three nuclear plants. A generic or an administrative letter is proposed as a more permanent solution. 1 fig.

Difficult OptEase Filter Retrievals After Prolonged Indwelling Times

Energy Technology Data Exchange (ETDEWEB)

Van Ha, Thuong G., E-mail: tgvanha@radiology.bsd.uchicago.edu; Kang, Lisa; Lorenz, Jonathan; Zangan, Steven; Navuluri, Rakesh; Straus, Christopher; Funaki, Brian [University of Chicago, Section of Interventional Radiology, Department of Radiology (United States)

2013-08-01

PurposeThe OptEase vena cave filter (Cordis, Piscataway, NJ) is commercially available as a retrievable or permanent filter with short recommended indwelling time, presumably due to extensive contact of the filter side struts with the inferior vena cava wall and subsequent neointimal hyperplasia leading to incorporation. Our purpose was to evaluate OptEase filter retrievals with a long indwelling time period that required unconventional retrieval techniques.Materials and MethodsWe retrospectively reviewed patients who underwent OptEase filter retrieval with long undwelling times requiring additional maneuvers for retrieval. Techniques used included rigid endobronchial forceps dissection and wire-through-loop snare. Each patient underwent postretrieval venogram to evaluate for possible complications. In addition, patients had clinical follow-up 2 weeks after the retrieval procedure.ResultsThere were three patients (2 women, 1 man; average age 64 years) who underwent OptEase filter retrieval. The mean indwelling time was 6.4 months. The indwelling filters were successfully retrieved. There were no complications. Postprocedural follow-up showed no clinical pathology.ConclusionUnconventional techniques aided in the retrieval of OptEase filters with long indwelling times.

Difficult OptEase Filter Retrievals After Prolonged Indwelling Times

International Nuclear Information System (INIS)

Van Ha, Thuong G.; Kang, Lisa; Lorenz, Jonathan; Zangan, Steven; Navuluri, Rakesh; Straus, Christopher; Funaki, Brian

2013-01-01

PurposeThe OptEase vena cave filter (Cordis, Piscataway, NJ) is commercially available as a retrievable or permanent filter with short recommended indwelling time, presumably due to extensive contact of the filter side struts with the inferior vena cava wall and subsequent neointimal hyperplasia leading to incorporation. Our purpose was to evaluate OptEase filter retrievals with a long indwelling time period that required unconventional retrieval techniques.Materials and MethodsWe retrospectively reviewed patients who underwent OptEase filter retrieval with long undwelling times requiring additional maneuvers for retrieval. Techniques used included rigid endobronchial forceps dissection and wire-through-loop snare. Each patient underwent postretrieval venogram to evaluate for possible complications. In addition, patients had clinical follow-up 2 weeks after the retrieval procedure.ResultsThere were three patients (2 women, 1 man; average age 64 years) who underwent OptEase filter retrieval. The mean indwelling time was 6.4 months. The indwelling filters were successfully retrieved. There were no complications. Postprocedural follow-up showed no clinical pathology.ConclusionUnconventional techniques aided in the retrieval of OptEase filters with long indwelling times

Experiment on Synchronous Timing Signal Detection from ISDB-T Terrestrial Digital TV Signal with Application to Autonomous Distributed ITS-IVC Network

Science.gov (United States)

Karasawa, Yoshio; Kumagai, Taichi; Takemoto, Atsushi; Fujii, Takeo; Ito, Kenji; Suzuki, Noriyoshi

A novel timing synchronizing scheme is proposed for use in inter-vehicle communication (IVC) with an autonomous distributed intelligent transport system (ITS). The scheme determines the timing of packet signal transmission in the IVC network and employs the guard interval (GI) timing in the orthogonal frequency divisional multiplexing (OFDM) signal currently used for terrestrial broadcasts in the Japanese digital television system (ISDB-T). This signal is used because it is expected that the automotive market will demand the capability for cars to receive terrestrial digital TV broadcasts in the near future. The use of broadcasts by automobiles presupposes that the on-board receivers are capable of accurately detecting the GI timing data in an extremely low carrier-to-noise ratio (CNR) condition regardless of a severe multipath environment which will introduce broad scatter in signal arrival times. Therefore, we analyzed actual broadcast signals received in a moving vehicle in a field experiment and showed that the GI timing signal is detected with the desired accuracy even in the case of extremely low-CNR environments. Some considerations were also given about how to use these findings.

Mechanical design and qualification of IR filter mounts and filter wheel of INSAT-3D sounder for low temperature

Science.gov (United States)

Vora, A. P.; Rami, J. B.; Hait, A. K.; Dewan, C. P.; Subrahmanyam, D.; Kirankumar, A. S.

2017-11-01

Next generation Indian Meteorological Satellite will carry Sounder instrument having subsystem of filter wheel measuring Ø260mm and carrying 18 filters arranged in three concentric rings. These filters made from Germanium, are used to separate spectral channels in IR band. Filter wheel is required to be cooled to 214K and rotated at 600 rpm. This Paper discusses the challenges faced in mechanical design of the filter wheel, mainly filter mount design to protect brittle germanium filters from failure under stresses due to very low temperature, compactness of the wheel and casings for improved thermal efficiency, survival under vibration loads and material selection to keep it lighter in weight. Properties of Titanium, Kovar, Invar and Aluminium materials are considered for design. The mount has been designed to accommodate both thermal and dynamic loadings without introducing significant aberrations into the optics or incurring permanent alignment shifts. Detailed finite element analysis of mounts was carried out for stress verification. Results of the qualification tests are discussed for given temperature range of 100K and vibration loads of 12g in Sine and 11.8grms in Random at mount level. Results of the filter wheel qualification as mounted in Electro Optics Module (EOM) are also presented.

Virulence of viral hemorrhagic septicemia virus (VHSV) genotypes Ia, IVa, IVb, and IVc in five fish species.

Science.gov (United States)

Emmenegger, Eveline J.; Moon, Chang Hoon; Hershberger, Paul K.; Kurath, Gael

2013-01-01

The susceptibility of yellow perch Perca flavescens, rainbow trout Oncorhynchus mykiss, Chinook salmon O. tshawytscha, koi Cyprinus carpio koi, and Pacific herring Clupea pallasii to 4 strains of viral hemorrhagic septicemia virus (VHSV) was assessed. Fish were challenged via intraperitoneal injection with high (1 × 106 plaque-forming units, PFU) and low (1 × 103 PFU) doses of a European strain (genotype Ia), and North American strains from the West coast (genotype IVa), Great Lakes (genotype IVb), and the East coast (genotype IVc). Pacific herring were exposed to the same VHSV strains, but at a single dose of 5 × 103 PFU ml-1 by immersion in static seawater. Overall, yellow perch were the most susceptible, with cumulative percent mortality (CPM) ranging from 84 to 100%, and 30 to 93% in fish injected with high or low doses of virus, respectively. Rainbow trout and Chinook salmon experienced higher mortalities (47 to 98% CPM) after exposure to strain Ia than to the other virus genotypes. Pacific herring were most susceptible to strain IVa with an average CPM of 80% and moderately susceptible (42 to 52% CPM) to the other genotypes. Koi had very low susceptibility (≤5.0% CPM) to all 4 VHSV strains. Fish tested at 7 d post challenge were positive for all virus strains, with yellow perch having the highest prevalence and concentrations of virus, and koi the lowest. While genotype Ia had higher virulence in salmonid species, there was little difference in virulence or host-specificity between isolates from subtypes IVa, IVb, and IVc.  

Yellow filters can improve magnocellular function: motion sensitivity, convergence, accommodation, and reading.

Science.gov (United States)

Ray, N J; Fowler, S; Stein, J F

2005-04-01

The magnocellular system plays an important role in visual motion processing, controlling vergence eye movements, and in reading. Yellow filters may boost magnocellular activity by eliminating inhibitory blue input to this pathway. It was found that wearing yellow filters increased motion sensitivity, convergence, and accommodation in many children with reading difficulties, both immediately and after three months using the filters. Motion sensitivity was not increased using control neutral density filters. Moreover, reading-impaired children showed significant gains in reading ability after three months wearing the filters compared with those who had used a placebo. It was concluded that yellow filters can improve magnocellular function permanently. Hence, they should be considered as an alternative to corrective lenses, prisms, or exercises for treating poor convergence and accommodation, and also as an aid for children with reading problems.

[Clinical analysis of patients with lower extremity deep venous thrombosis complicated with inferior vena cava thrombus].

Science.gov (United States)

Dong, Dian-ning; Wu, Xue-jun; Zhang, Shi-yi; Zhong, Zhen-yue; Jin, Xing

2013-06-04

To explore the clinical profiles of patients with lower extremity deep venous thrombosis (DVT) complicated with inferior vena cava (IVC) thrombus and summarize their clinical diagnostic and therapeutic experiences. The clinical characteristics, diagnosis and treatment of 20 hospitalized patients with DVT complicated with inferior vena cava thrombus were analyzed retrospectively. All of them were of proximal DVT. There were phlegmasia cerulea dolens (n = 3), pulmonary embolism (n = 3) and completely occlusion of IVC (n = 5). Clinical manifestations were severe. Retrievable inferior vena cava filter (IVCF) was implanted for 17 cases. Catheter-directed thrombolysis (CDT) through ipsilateral popliteal vein was applied for 7 cases and systemic thrombolysis therapy for 8 cases. The effective rate of thrombolysis for fresh IVC thrombus was 100%. Among 5 cases with Cockett Syndrome, 3 cases underwent balloon dilatation angioplasty and endovascular stenting of iliac vein. And 17 IVCFs were retrieved successfully within 3 weeks. IVC thrombus disappeared completely in 15 cases. Systemic or local thrombolysis with protective IVCF is a safe and effective therapy for nonocclusive IVC thrombus in DVT. And CDT is recommended for symptomatic occlusive IVC thrombus.

On Position Sensorless Control for Permanent Magnet Synchronous Motor Based on a New Sliding Mode Observer

Directory of Open Access Journals (Sweden)

Qixin Zhu

2014-10-01

Full Text Available For the problems of buffeting and phase delay in traditional rotor detection in sensorless vector control of permanent magnet synchronous motor (PMSM, the Sigmoid function is proposed to replace sign function and the approach of piecewise linearization is proposed to compensate phase delay. To the problem that the output of traditional low pass filter contains high- order harmonic, two-stage filter including traditional low-pass filter and Kalman filter is proposed in this paper. Based on the output of traditional first-order low-pass filter, the Kalman filter is used to get modified back-EMF. The phase-locked loop control of rotor position is adopted to estimate motor position and speed. A Matlab/Simulink simulation model of PMSM position servo control system is established. The simulation analysis of the new sliding mode observer’s back-EMF detection, position and speed estimation, load disturbance and dynamic process are carried out respectively. Simulation results verify feasibility of the new sliding mode observer algorithm.

Removal of particulate matter emitted from a subway tunnel using magnetic filters.

Science.gov (United States)

Son, Youn-Suk; Dinh, Trieu-Vuong; Chung, Sang-Gwi; Lee, Jai-Hyo; Kim, Jo-Chun

2014-01-01

We removed particulate matter (PM) emitted from a subway tunnel using magnetic filters. A magnetic filter system was installed on the top of a ventilation opening. Magnetic field density was increased by increasing the number of permanent magnet layers to determine PM removal characteristics. Moreover, the fan's frequency was adjusted from 30 to 60 Hz to investigate the effect of wind velocity on PM removal efficiency. As a result, PM removal efficiency increased as the number of magnetic filters or fan frequency increased. We obtained maximum removal efficiency of PM10 (52%), PM2.5 (46%), and PM1 (38%) at a 60 Hz fan frequency using double magnetic filters. We also found that the stability of the PM removal efficiency by the double filter (RSD, 3.2-5.8%) was higher than that by a single filter (10.9-24.5%) at all fan operating conditions.

Design and fabrication of magnetic coolant filter

Science.gov (United States)

Prashanth, B. N.

2017-07-01

Now a day's use of coolants in industry has become dominant because of high production demands. Coolants not only help in speeding up the production but also provide many advantages in the metal working operation. As the consumption of coolants is very high a system is badly in need, so as to recirculate the used coolant. Also the amount of hazardous waste generated by industrial plants has become an increasingly costly problem for the manufactures and an additional stress on the environment. Since the purchase and disposal of the spent cutting fluids is becoming increasingly expensive, fluid recycling is a viable option for minimizing the cost. Separation of metallic chips from the coolants by using magnetic coolant separation has proven a good management and maintenance of the cutting fluid. By removing the metallic chips, the coolant life is greatly extended, increases the machining quality and reduces downtime. Above being the case, a magnetic coolant filter is developed which utilizes high energy permanent magnets to develop a dense magnetic field along a narrow flow path into which the contaminated coolant is directed. The ferromagnetic particles captured and aligned by the dense magnetic field, from the efficient filter medium. This enables the unit to remove ferromagnetic particles from the coolant. Magnetic coolant filters use the principle of magnetic separation to purify the used coolant. The developed magnetic coolant separation has the capability of purifying 40 litres per minute of coolant with the size of the contaminants ranging from 1 µm to 30 µm. The filter will be helpful in saving the production cost as the cost associated with the proposed design is well justified by the cost savings in production. The magnetic field produced by permanent magnets will be throughout the area underneath the reservoir. This produces magnetic field 30mm above the coolant reservoir. Very fine particles are arrested without slip. The magnetic material used will not

KILT (Kidney and IVC Abnormalities with Leg Thrombosis) Syndrome in a 41-Years-Old Man with Loin Pain and Fever.

Science.gov (United States)

Fung, James Kiujing; Yeung, Victor Hip Wo; Chu, Sau Kwan; Man, Chi Wan

2017-05-01

KILT syndrome is a rare condition composing the triad of kidney and inferior vena cava anomaly and extensive venous thrombosis. We present a case of newly diagnosed KILT syndrome in a 41-years-old gentleman presenting with loin pain and fever. Reviewing previous case reports, KILT syndrome is usually an incidental finding on imaging studies and there is a wide scope of initial clinical presentations. However, recent evidence suggests IVC anomaly may have caused subsequent renal hypoplasia. Identification of the underlying etiology may be helpful in planning early vascular intervention to treat the condition.

Biodegradable microfabricated plug-filters for glaucoma drainage devices.

Science.gov (United States)

Maleki, Teimour; Chitnis, Girish; Park, Jun Hyeong; Cantor, Louis B; Ziaie, Babak

2012-06-01

We report on the development of a batch fabricated biodegradable truncated-cone-shaped plug filter to overcome the postoperative hypotony in nonvalved glaucoma drainage devices. Plug filters are composed of biodegradable polymers that disappear once wound healing and bleb formation has progressed past the stage where hypotony from overfiltration may cause complications in the human eye. The biodegradable nature of device eliminates the risks associated with permanent valves that may become blocked or influence the aqueous fluid flow rate in the long term. The plug-filter geometry simplifies its integration with commercial shunts. Aqueous humor outflow regulation is achieved by controlling the diameter of a laser-drilled through-hole. The batch compatible fabrication involves a modified SU-8 molding to achieve truncated-cone-shaped pillars, polydimethylsiloxane micromolding, and hot embossing of biodegradable polymers. The developed plug filter is 500 μm long with base and apex plane diameters of 500 and 300 μm, respectively, and incorporates a laser-drilled through-hole with 44-μm effective diameter in the center.

Placement of a Retrievable Guenther Tulip Filter in the Superior Vena Cava for Upper Extremity Deep Venous Thrombosis

International Nuclear Information System (INIS)

Nadkarni, Sanjay; Macdonald, Sumaira; Cleveland, Trevor J.; Gaines, Peter A.

2002-01-01

A retrievable Guenther Tulip caval filter(William Cook, Europe) was successfully placed and retrieved in the superior vena cava for upper extremity deep venous thrombosis in a 56-year-old woman. Bilateral subclavian and internal jugular venous thromboses thought secondary to placement of multiple central venous catheters were present. There have been reports of the use of permanent Greenfield filters and a single case report of a temporary filter in the superior vena cava. As far as we are aware this is the first reported placement and successful retrieval of a filter in these circumstances

State Estimation of Permanent Magnet Synchronous Motor Using Improved Square Root UKF

Directory of Open Access Journals (Sweden)

Bo Xu

2016-06-01

Full Text Available This paper focuses on an improved square root unscented Kalman filter (SRUKF and its application for rotor speed and position estimation of permanent magnet synchronous motor (PMSM. The approach, which combines the SRUKF and strong tracking filter, uses the minimal skew simplex transformation to reduce the number of the sigma points, and utilizes the square root filtering to reduce computational errors. The time-varying fading factor and softening factor are introduced to self-adjust the gain matrices and the state forecast covariance square root matrix, which can realize the residuals orthogonality and force the SRUKF to track the real state rapidly. The theoretical analysis of the improved SRUKF and implementation details for PMSM state estimation are examined. The simulation results show that the improved SRUKF has higher nonlinear approximation accuracy, stronger numerical stability and computational efficiency, and it is an effective and powerful tool for PMSM state estimation under the conditions of step response or load disturbance.

Research on the filtering algorithm in speed and position detection of maglev trains.

Science.gov (United States)

Dai, Chunhui; Long, Zhiqiang; Xie, Yunde; Xue, Song

2011-01-01

This paper introduces in brief the traction system of a permanent magnet electrodynamic suspension (EDS) train. The synchronous traction mode based on long stators and track cable is described. A speed and position detection system is recommended. It is installed on board and is used as the feedback end. Restricted by the maglev train's structure, the permanent magnet electrodynamic suspension (EDS) train uses the non-contact method to detect its position. Because of the shake and the track joints, the position signal sent by the position sensor is always aberrant and noisy. To solve this problem, a linear discrete track-differentiator filtering algorithm is proposed. The filtering characters of the track-differentiator (TD) and track-differentiator group are analyzed. The four series of TD are used in the signal processing unit. The result shows that the track-differentiator could have a good effect and make the traction system run normally.

Filter Influence on Rotor Losses in Coreless Axial Flux Permanent Magnet Machines

Directory of Open Access Journals (Sweden)

SANTIAGO, J.

2013-02-01

Full Text Available This paper investigates the eddy current losses induced in the rotor of coreless Axial-Flux machines. The calculation of eddy currents in the magnets requires the simulation of the inverter and the filter to obtain the harmonic content of the stator currents and FEM analysis of the magnets in the rotor. Due to the low inductance in coreless machines, the induced eddy current losses in the rotor remain lower than in traditional slotted machines. If only machine losses are considered, filters in DC/AC converters are not required in machines with wide airgaps as time harmonic losses in the rotor are very low.The harmonic content both from simulations and experimental results of a DC/AC converter are used to calculate the eddy currents in the rotor magnets. The properties of coreless machine topologies are investigated and some simplifications are proposed for time efficient 3D-FEM analysis. The time varying magnetic field can be considered constant over the magnets when the pole is divided in several magnets.The simplified FEM method to calculate eddy current losses is applicable to coreless machines with poles split into several magnets, although the conclusions are applicable to all coreless and slotless motors and generators.

A chiral-based magnetic memory device without a permanent magnet.

Science.gov (United States)

Ben Dor, Oren; Yochelis, Shira; Mathew, Shinto P; Naaman, Ron; Paltiel, Yossi

2013-01-01

Several technologies are currently in use for computer memory devices. However, there is a need for a universal memory device that has high density, high speed and low power requirements. To this end, various types of magnetic-based technologies with a permanent magnet have been proposed. Recent charge-transfer studies indicate that chiral molecules act as an efficient spin filter. Here we utilize this effect to achieve a proof of concept for a new type of chiral-based magnetic-based Si-compatible universal memory device without a permanent magnet. More specifically, we use spin-selective charge transfer through a self-assembled monolayer of polyalanine to magnetize a Ni layer. This magnitude of magnetization corresponds to applying an external magnetic field of 0.4 T to the Ni layer. The readout is achieved using low currents. The presented technology has the potential to overcome the limitations of other magnetic-based memory technologies to allow fabricating inexpensive, high-density universal memory-on-chip devices.

Research on the Filtering Algorithm in Speed and Position Detection of Maglev Trains

Directory of Open Access Journals (Sweden)

Chunhui Dai

2011-07-01

Full Text Available This paper introduces in brief the traction system of a permanent magnet electrodynamic suspension (EDS train. The synchronous traction mode based on long stators and track cable is described. A speed and position detection system is recommended. It is installed on board and is used as the feedback end. Restricted by the maglev train’s structure, the permanent magnet electrodynamic suspension (EDS train uses the non-contact method to detect its position. Because of the shake and the track joints, the position signal sent by the position sensor is always aberrant and noisy. To solve this problem, a linear discrete track-differentiator filtering algorithm is proposed. The filtering characters of the track-differentiator (TD and track-differentiator group are analyzed. The four series of TD are used in the signal processing unit. The result shows that the track-differentiator could have a good effect and make the traction system run normally.

Relationship between changes of blood HBV-DNA viral load and serum liver fibrosis markers (HA, LN, IV-C, PCIII) levels in patients with chronic hepatitis B

International Nuclear Information System (INIS)

Wang Yuanchi; Huang Jinwei

2009-01-01

Objective: To investigate the relationship between changes of blood HBV DNA viral load and serum liver fibrosis markers levels in patients with chronic hepatitis B. Methods: In 2002, 20 patients with hepatitis B were divided into two groups: Group A treated with antiviral ageat (n=10), Group B not treated.Five years later (2007) the blood viral load (with FQ-PCR) and serum levels of hepatic fibrosis markers (with RIA) were determined in these patients. Results: The average log viral load in serum in the tow groups were 3.56 ± 1.12 (treated group) and 7.76 ± 1.23 respectively with significant difference (P<0.05). In 2002, serum liver fibrosis markers (HA, LN, IV-C, PCIII) levels were about the same in the two groups were (82.72 ± 30.62μg/ml, 71.18 ± 26.71μg/ml, 93.77 ± 69.87μg/ml, 91.4 ± 18.64μg/ml and 79.32 ± 31.34μg/ml, 70.25 ± 28.23)μg/ml, 90.35 ± 67.81μg/ml, 85.77 ± 20.56μg/ml respectively). In 2007, in the treated patients, serum liver fibrosis markers HA, LN, IV-C, PCIII levels were 85.72 ± 29.52μg/ml, 70.18 ± 25.4μg/ml, 94.2 ± 70.92μg/ml, 93.4 ± 19.32μg/ml respectively However, in the non-treated groups, the serum HA, LN, IV-C, PCIII levels were105.67 ± 28.54μg/ml, 97.75 ± 26.25μg/ml, 132 ± 72.13μg/ml, 120.72 ± 19.87μg/ml, being significantly higher than those in the treated group (P<0.05). Conclusion: Effective decrease of the viral load might control the progress of hepatic fibrosis in patients with chronic hepatitis B. (authors)

Heart block and cardiac embolization of fractured inferior vena cava filter.

Science.gov (United States)

Abudayyeh, Islam; Takruri, Yessar; Weiner, Justin B

2016-01-01

A 66-year-old man underwent a placement of an inferior vena cava filter before a gastric surgery 9 years prior, presented to the emergency room with a complete atrioventricular block. Chest x-ray and transthoracic echocardiogram showed struts migrating to right ventricle with tricuspid regurgitation. Cardiothoracic surgery was consulted and declined an open surgical intervention due to the location of the embolized fragments and the patient's overall condition. It was also felt that the fragments had migrated chronically and were adhered to the cardiac structures. The patient underwent a dual-chamber permanent pacemaker implantation. Post-implant fluoroscopy showed no displacement of the inferior vena cava filter struts due to the pacemaker leads indicating that the filter fracture had likely been a chronic process. This case highlights a rare combination of complications related to inferior vena cava filter fractures and the importance of assessing for such fractures in chronic placements. Inferior vena cava filter placement for a duration greater than 1 month can be associated with filter fractures and strut migration which may lead to, although rare, serious or fatal complications such as complete atrioventricular conduction system disruption and valvular damage including significant tricuspid regurgitation. Assessing for inferior vena cava filter fractures in chronic filter placement is important to avoid such complications. When possible, retrieval of the filter should be considered in all patients outside the acute setting in order to avoid filter-related complications. Filter retrieval rates remain low even when a retrievable filter is in place and the patient no longer has a contraindication to anticoagulation.

A rare nidus for pulmonary thromboembolism after vertebroplasty.

Science.gov (United States)

Vallabhajosyula, Saraschandra; Sundaragiri, Pranathi Rao; Bansal, Ojas; Townley, Theresa A

2013-10-23

Percutaneous vertebroplasty is used to treat osteoporotic compression fractures and bone loss due to malignancy. The cement used can serve as a potential nidus for pulmonary thromboembolism (PTE). An 87-year-old woman with recent L2 vertebroplasty presented with abdominal pain and shortness of breath. Thoracoabdominal CT scan revealed extensive bilateral pulmonary emboli associated with a 9 cm cement fragment in the inferior vena cava (IVC) extending proximally from the level of the right superior renal vein, likely secondary to cement leak from the vertebral plexus into the IVC. She refused catheter extraction was managed conservatively. There are 51 reported cases of cement pulmonary embolism. IVC foreign bodies serving as a nidus for PTE have been reported with IVC filters with an incidence of 6.2%. This is the second reported case of vertebroplasty cement serving as a nidus for PTE. Treatment depends on time interval between the procedure and the symptom onset.

Factors Associated with Advanced Inferior Vena Cava Filter Removals: A Single-Center Retrospective Study of 203 Patients Over 7 Years

Energy Technology Data Exchange (ETDEWEB)

Dowell, Joshua D., E-mail: Joshua.Dowell@osumc.edu; Wagner, Daniel, E-mail: Daniel.Wagner@osumc.edu; Elliott, Eric, E-mail: Eric.Elliott@osumc.edu [The Ohio State University Wexner Medical Center, Department of Radiology, Division of Interventional Radiology (United States); Yildiz, Vedat O., E-mail: Vedat.Yildiz@osumc.edu; Pan, Xueliang, E-mail: Jeff.Pan@osumc.edu [The Ohio State University Wexner Medical Center, Center for Biostatistics (United States)

2016-02-15

PurposeTo identify factors associated with advanced inferior vena cava filter (IVCF) retrieval to raise awareness on technical considerations, retrieval efficiency, and patient safety.Materials and MethodsA single-center retrospective review was performed of 203 consecutive retrievable IVC filters placed between 2007 and 2014. Attempted retrievals were classified as advanced if the routine “snare and sheath” technique was initially unsuccessful after multiple attempts, or an alternate endovascular maneuver or access site was utilized. Patient and filter characteristics were recorded.Results203 attempted retrievals were reviewed (48.7 % male, 51.2 % female, mean age 52.7 years, mean dwell time 109 days). Advanced retrievals were observed in 20 patients (9.8 %) (15 females, 5 males). Fluoroscopy time (p ≤ 0.01, 34.3 ± 21.1 and 5.3 ± 4.5 min for advanced retrievals and routine retrievals respectively, same below), gender (p = 0.031), and retrieval tilt angle (p ≤ 0.01, 5.7 ± 5.10° vs. 11.9 ± 11.03°) were associated with advanced retrievals. Females were 3.16 times more likely to have an advanced retrieval performed than males with a significantly higher tilt angle in those with advanced retrieval. History of cancer (p = 0.502), dwell time (p = 0.916), retrieval caval diameter (p = 0.053), placement caval diameter (p = 0.365), filter type (p = 0.710), strut perforation (p = 0.506), placement tilt angle (p = 0.311), and age (p = 0.558) were not found significantly associated with advanced retrievals.ConclusionsWomen are at increased risk for advanced filter retrieval secondary to a significant change in filter tilt over time compared to men, independent of filter type or competing demographic or filter risks, likely placing them at increased risk for higher procedural fluoroscopy times.

Factors Associated with Advanced Inferior Vena Cava Filter Removals: A Single-Center Retrospective Study of 203 Patients Over 7 Years

International Nuclear Information System (INIS)

Dowell, Joshua D.; Wagner, Daniel; Elliott, Eric; Yildiz, Vedat O.; Pan, Xueliang

2016-01-01

PurposeTo identify factors associated with advanced inferior vena cava filter (IVCF) retrieval to raise awareness on technical considerations, retrieval efficiency, and patient safety.Materials and MethodsA single-center retrospective review was performed of 203 consecutive retrievable IVC filters placed between 2007 and 2014. Attempted retrievals were classified as advanced if the routine “snare and sheath” technique was initially unsuccessful after multiple attempts, or an alternate endovascular maneuver or access site was utilized. Patient and filter characteristics were recorded.Results203 attempted retrievals were reviewed (48.7 % male, 51.2 % female, mean age 52.7 years, mean dwell time 109 days). Advanced retrievals were observed in 20 patients (9.8 %) (15 females, 5 males). Fluoroscopy time (p ≤ 0.01, 34.3 ± 21.1 and 5.3 ± 4.5 min for advanced retrievals and routine retrievals respectively, same below), gender (p = 0.031), and retrieval tilt angle (p ≤ 0.01, 5.7 ± 5.10° vs. 11.9 ± 11.03°) were associated with advanced retrievals. Females were 3.16 times more likely to have an advanced retrieval performed than males with a significantly higher tilt angle in those with advanced retrieval. History of cancer (p = 0.502), dwell time (p = 0.916), retrieval caval diameter (p = 0.053), placement caval diameter (p = 0.365), filter type (p = 0.710), strut perforation (p = 0.506), placement tilt angle (p = 0.311), and age (p = 0.558) were not found significantly associated with advanced retrievals.ConclusionsWomen are at increased risk for advanced filter retrieval secondary to a significant change in filter tilt over time compared to men, independent of filter type or competing demographic or filter risks, likely placing them at increased risk for higher procedural fluoroscopy times

The permanent process

DEFF Research Database (Denmark)

Møller, Jesper; McCullagh, Peter

We extend the boson process first to a large class of Cox processes and second an even larger class of infinitely divisible point processes. Density and moment results are studied in detail. These results are obtained in closed form as weighted permanents, so the extension is called a permanent...... process. Temporal extensions and a particularly tractable case of the permanent process are also studied. Extensions of the ferminon process along similar lines, leading to so-called determinant processes, are discussed at the end. While the permanent process is attractive, the determinant process...

Improvement of stability of polidocanol foam for nonsurgical permanent contraception.

Science.gov (United States)

Guo, Jian Xin; Lucchesi, Lisa; Gregory, Kenton W

2015-08-01

Polidocanol foam (PF), used clinically as a venous sclerosant, has recently been studied as a safe and inexpensive means for permanent contraception. Delivering the sclerosant to the fallopian tubes as a foam rather than a liquid increases the surface areas and thus enhances the desired epithelial disrupting activity of the agent. However, the foam is inherently unstable and degrades with time. Therefore, increasing foam stability and thus duration of the agent exposure time could increase epithelial effect while allowing reduction in agent concentration and potential toxicity. We studied methods to improve foam properties that might improve safety and efficacy of PF for intrauterine application. Several types of microporous filters adapted to a syringe-based foaming device were used to study the effect of pore structures on the formation of PF. The foam drainage time and bubble size were characterized. The addition of benzalkonium chloride (BZK) to polidocanol was also investigated for its effects on foam characteristics. A syringe-based foaming device adapted with an inline filter produced smaller bubble PF with a longer foam drainage time. PF generated with a circular pore filter lasts longer than with a noncircular pore filter. The addition of 0.01% of BZK also improved the stability of PF. The stability of PF is affected by the pore characteristics of the filter used for foam generation and enhanced by the presence of a small amount of BZK. The improved foam, if shown to be efficacious in animal models of contraception, could lead to a safe, simple and inexpensive method alternative to surgical contraception. Copyright © 2015 Elsevier Inc. All rights reserved.

Half Size Reduction of DC Output Filter Inductors With the Saturation-Gap Magnetic Bias Topology

DEFF Research Database (Denmark)

Aguilar, Andres Revilla; Munk-Nielsen, Stig

2016-01-01

Filter inductors are probably one of the heaviest and more voluminous components found in power supplies of most electronic devices. A known technique to reduce the inductor size in dc applications is the use of permanent magnet inductors (PMIs). One of the latest developed biasing topologies...

Community-acquired necrotizing pneumonia caused by methicillin-resistant Staphylococcus aureus ST30-SCCmecIVc-spat019-PVL positive in San Antonio de Areco, Argentina

Directory of Open Access Journals (Sweden)

Silvina Fernández

2015-03-01

Full Text Available Community-acquired methicillin-resistant Staphylococcus aureus is the first cause of skin and soft tissue infections, but can also produce severe diseases such as bacteremia, osteomyelitis and necrotizing pneumonia. Some S. aureus lineages have been described in cases of necrotizing pneumonia worldwide, usually in young, previously healthy patients. In this work, we describe a fatal case of necrotizing pneumonia due to community-acquired methicillin-resistant S. aureus clone ST30-SCCmecIVc-spat019-PVL positive in an immunocompetent adult patient.

The Question of Decalage Between Object Permanence and Person Permanence

Science.gov (United States)

And Others; Jackson, Elaine

1978-01-01

Presents a study of decalage between object permanence and person permanence. Decalage was influenced by environmental as well as stimulus factors with infants tested between 6- and 81/4-months/of-age. (BD)

Essure Permanent Birth Control

Science.gov (United States)

... Prosthetics Essure Permanent Birth Control Essure Permanent Birth Control Share Tweet Linkedin Pin it More sharing options ... Print Essure is a a permanently implanted birth control device for women (female sterilization). Implantation of Essure ...

Percutaneous Selective Embolectomy using a Fogarty Thru-Lumen Catheter for Pancreas Graft Thrombosis: A Case Report

International Nuclear Information System (INIS)

Izaki, Kenta; Yamaguchi, Masato; Matsumoto, Ippei; Shinzeki, Makoto; Ku, Yonson; Sugimura, Kazuro; Sugimoto, Koji

2011-01-01

A 57-year-old woman with a history of diabetes mellitus underwent simultaneous pancreas–kidney transplantation. The pancreaticoduodenal graft was implanted in the right iliac fossa. The donor’s portal vein was anastomosed to the recipient’s inferior vena cava (IVC). Seven days after the surgery, a thrombus was detected in the graft veins. Percutaneous thrombolysis was immediately performed; however, venous congestion was still present. We therefore attempted selective embolectomy using a Fogarty Thru-Lumen Catheter. Thrombi were directed from the graft veins toward the IVC and captured in the IVC filter with complete elimination of the thrombus without any major complications. We present our technique for the successful treatment of pancreas graft thrombosis within a short time period by percutaneous selective embolectomy using a Fogarty Thru-Lumen Catheter.

Permanences GAG-EPA

CERN Document Server

GAC-EPA

2015-01-01

Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 5 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 2 juin, 1er septembre, 6 octobre, 3 novembre et 1er décembre 2015. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

Endovascular Treatment for Iliac Vein Compression Syndrome: a Comparison between the Presence and Absence of Secondary Thrombosis

Energy Technology Data Exchange (ETDEWEB)

Lou, Wen Sheng; Gu, Jian Ping; He, Xu; Chen, Liang; Su, Hao Bo; Chen, Guo Ping; Song, Jing Hua; Wang, Tao [Nanjing First Hospital Affiliated to Nanjing Medical University, Nanjing (China)

2009-04-15

To evaluate the value of early identification and endovascular treatment of iliac vein compression syndrome (IVCS), with or without deep vein thrombosis (DVT). Three groups of patients, IVCS without DVT (group 1, n = 39), IVCS with fresh thrombosis (group 2, n = 52) and IVCS with non-fresh thrombosis (group 3, n = 34) were detected by Doppler ultrasonography, magnetic resonance venography, computed tomography or venography. The fresh venous thrombosis were treated by aspiration and thrombectomy, whereas the iliac vein compression per se were treated with a self-expandable stent. In cases with fresh thrombus, the inferior vena cava filter was inserted before the thrombosis suction, mechanical thrombus ablation, percutaneous transluminal angioplasty, stenting or transcatheter thrombolysis. Stenting was performed in 111 patients (38 of 39 group 1 patients and 73 of 86 group 2 or 3 patients). The stenting was tried in one of group 1 and in three of group 2 or 3 patients only to fail. The initial patency rates were 95% (group 1), 89% (group 2) and 65% (group 3), respectively and were significantly different (p = 0.001). Further, the six month patency rates were 93% (group 1), 83% (group 2) and 50% (group 3), respectively, and were similarly significantly different (p = 0.001). Both the initial and six month patency rates in the IVCS patients (without thrombosis or with fresh thrombosis), were significantly greater than the patency rates of IVCS patients with non-fresh thrombosis. From the cases examined, the study suggests that endovascular treatment of IVCS, with or without thrombosis, is effective

Inverter Output Filter Effect on PWM Motor Drives of a Flywheel Energy Storage System

Science.gov (United States)

Santiago, Walter

2004-01-01

NASA Glenn Research Center (GRC) has been involved in the research and development of high speed flywheel systems for small satellite energy storage and attitude control applications. One research and development area has been the minimization of the switching noise produced by the pulsed width modulated (PWM) inverter that drives the flywheel permanent magnet motor/generator (PM M/G). This noise can interfere with the flywheel M/G hardware and the system avionics hampering the full speed performance of the flywheel system. One way to attenuate the inverter switching noise is by placing an AC filter at the three phase output terminals of the inverter with the filter neutral point connected to the DC link (DC bus) midpoint capacitors. The main benefit of using an AC filter in this fashion is the significant reduction of the inverter s high dv/dt switching and its harmonics components. Additionally, common mode (CM) and differential mode (DM) voltages caused by the inverter s high dv/dt switching are also reduced. Several topologies of AC filters have been implemented and compared. One AC filter topology consists of a two-stage R-L-C low pass filter. The other topology consists of the same two-stage R-L-C low pass filter with a series connected trap filter (an inductor and capacitor connected in parallel). This paper presents the analysis, design and experimental results of these AC filter topologies and the comparison between the no filter case and conventional AC filter.

3-D analysis of eddy current in permanent magnet of interior permanent magnet motors

International Nuclear Information System (INIS)

Kawase, Yoshihiro; Yamaguchi, Tadashi; Fukanaga, Hiromu; Ito, Shokichi

2002-01-01

Interior permanent magnet motors are widely used in various fields. However, in high-speed operations, it is important to decrease the eddy current loss in the permanent magnet. In order to decrease the eddy current loss, we propose to divide the permanent magnet. In this paper, we clarified the effect of division of permanent magnet on the eddy current loss using the 3-D finite element method. (Author)

Comparison of torque capability of three-phase permanent magnet synchronous motors with different permanent magnet arrangement

International Nuclear Information System (INIS)

Stumberger, Bojan; Stumberger, Gorazd; Hadziselimovic, Miralem; Hamler, Anton; Gorican, Viktor; Jesenik, Marko; Trlep, Mladen

2007-01-01

The paper presents a comparison of torque capability of three-phase permanent magnet synchronous motors with different permanent magnet arrangement. Motors with the following permanent magnet topologies were accounted for in the comparison: the surface-mounted permanent magnet synchronous motor (SMPMSM), the interior permanent magnet synchronous motor (IPMSM), the permanent magnet-assisted synchronous reluctance motor (PMASRM) and the flux reversal permanent magnet motor (FRPMM). Finite element method analysis is employed to determine the performance of each motor. Calculated performance of four-pole IPMSM determined by finite element method calculation is confirmed with the measurements at nearly constant nominal output power in the range of speed 3000-10,000 rpm

Permanent quadrupole magnets

International Nuclear Information System (INIS)

Bush, E.D. Jr.

1976-01-01

A family of quadrupole magnets using a soft iron return yoke and circular cross-section permanent magnet poles were fabricated to investigate the feasibility for use in ion or electron beam focusing applications in accelerators and transport lines. Magnetic field measurements yielded promising results. In fixed-field applications, permanent magnets with sufficient gradients would be a low cost substitute for conventional electromagnets, eliminating the need for power supplies, associated wiring, and cooling. Based on preliminary tests, it was seen that permanent quadrupole magnets can offer a low cost, reliable solution in applications requiring small, fixed-field focusing devices for use in ion or electron-beam transport systems. Permanent magnets do require special considerations in design, fabrication, handling, and service that are different than encountered in conventional quadrupole magnets. If these basic conditions are satisfied, the resulting beam-focusing device would be stable, maintenance free, with virtually an indefinite lifetime

DEVELOPMENT OF AN ADHESIVE CANDLE FILTER SAFEGUARD DEVICE; F

International Nuclear Information System (INIS)

John P. Hurley; Ann K. Henderson; Jan W. Nowok; Michael L. Swanson

2002-01-01

device at high temperatures in a dusty gas stream is difficult because of problems with materials corrosion, dust leakage, and detection of filter failure. Therefore, the Energy and Environmental Research Center is using its knowledge of the factors that make filter dust sticky at gas filtration temperatures to make a simple and inexpensive SGD that employs an adhesive yet thermodynamically stable coating on a highly porous ceramic substrate. The SGDs are placed on top of individual candle filters at the filtered gas exit. Upon failure of the filter, the dirty gas flows through the SGD where the adhesive surface rapidly and permanently traps dust particles, causing the device to plug and prevent the dust from reaching the turbine

Lisheen Nursing Home, Stoneylane, Rathcoole, Co. Dublin.

LENUS (Irish Health Repository)

Nagi, D

2010-01-01

Massive pulmonary embolism carries a high mortality. Potential treatment includes anticoagulation, thrombolytic therapy and embolectomy. We report a case of deep vein thrombosis leading to progressive massive pulmonary embolism despite appropriate anticoagulation, where thrombolysis with IVC filter placement resulted in a successful outcome.

Thrombolytic therapy in pulmonary embolism.

LENUS (Irish Health Repository)

Nagi, D

2010-01-01

Massive pulmonary embolism carries a high mortality. Potential treatment includes anticoagulation, thrombolytic therapy and embolectomy. We report a case of deep vein thrombosis leading to progressive massive pulmonary embolism despite appropriate anticoagulation, where thrombolysis with IVC filter placement resulted in a successful outcome.

Should We Remove the Retrievable Cook Celect Inferior Vena Cava Filter? Eight Years of Experience at a Single Center.

Science.gov (United States)

Son, Joohyung; Bae, Miju; Chung, Sung Woon; Lee, Chung Won; Huh, Up; Song, Seunghwan

2017-12-01

The inferior vena cava filter (IVCF) is very effective for preventing pulmonary embolism in patients who cannot undergo anticoagulation therapy. However, if a filter is placed in the body permanently, it may lead to other complications. A retrospective study was performed of 159 patients who underwent retrievable Cook Celect IVCF implantation between January 2007 and April 2015 at a single center. Baseline characteristics, indications, and complications caused by the filter were investigated. The most common underlying disease of patients receiving the filter was cancer (24.3%). Venous thrombolysis or thrombectomy was the most common indication for IVCF insertion in this study (47.2%). The most common complication was inferior vena cava penetration, the risk of which increased the longer the filter remained in the body (p=0.032, Exp(B)=1.004). If the patient is able to retry anticoagulation therapy and the filter is no longer needed, the filter should be removed, even if a long time has elapsed since implantation. If the filter cannot be removed, it is recommended that follow-up computed tomography be performed regularly to monitor the progress of venous thromboembolisms as well as any filter-related complications.

SU-G-IeP4-15: Ultrasound Imaging of Absorbable Inferior Vena Cava Filters for Proper Placement

Energy Technology Data Exchange (ETDEWEB)

Mitcham, T; Bouchard, R; Melancon, A; Melancon, M [University of Texas MD Anderson Cancer Center, Houston, TX (United States); Eggers, M [Adient Medical Technologies, Pearland, TX (United States)

2016-06-15

Purpose: Inferior vena cava filters (IVCFs) are used in patients with a high risk of pulmonary embolism in situations when the use of blood thinning drugs would be inappropriate. These filters are implanted under x-ray guidance; however, this provides a dose of ionizing radiation to both patient and physician. B-mode ultrasound (US) imaging allows for localization of certain implanted devices without radiation dose concerns. The goal of this study was to investigate the feasibility of imaging the placement of absorbable IVCFs using US imaging to alleviate the dosage concern inherent to fluoroscopy. Methods: A phantom was constructed to mimic a human IVC using tissue-mimicking material with 0.5 dB/cm/MHz acoustic attenuation, while agar inclusions were used to model acoustic mismatch at the venous interface. Absorbable IVCF’s were imaged at 15 cm depth using B-mode US at 2, 3, 5, and 7 MHz transmit frequencies. Then, to determine temporal stability, the IVCF was left in the phantom for 10 weeks; during this time, the IVCF was imaged using the same techniques as above, while the integrity of the filter was analyzed by inspecting for fiber discontinuities. Results: Visualization of the inferior vena cava filter was possible at 5, 7.5, and 15 cm depth at US central frequencies of 2, 3, 5, and 7 MHz. Imaging the IVCF at 5 MHz yielded the clearest images while maintaining acceptable spatial resolution for identifying the IVCF’s, while lower frequencies provided noticeably worse image quality. No obvious degradation was observed over the course of the 10 weeks in a static phantom environment. Conclusion: Biodegradable IVCF localization was possible up to 15 cm in depth using conventional B-mode US in a tissue-mimicking phantom. This leads to the potential for using B-mode US to guide the placement of the IVCF upon deployment by the interventional radiologist. Mitch Eggers is an owner of Adient Medical Technologies. There are no other conflicts of interest to disclose.

Community-acquired necrotizing pneumonia caused by methicillin-resistant Staphylococcus aureus ST30-SCCmecIVc-spat019-PVL positive in San Antonio de Areco, Argentina.

Science.gov (United States)

Fernandez, Silvina; Murzicato, Sofía; Sandoval, Orlando; Fernández-Canigia, Liliana; Mollerach, Marta

2015-01-01

Community-acquired methicillin-resistant Staphylococcus aureus is the first cause of skin and soft tissue infections, but can also produce severe diseases such as bacteremia, osteomyelitis and necrotizing pneumonia. Some S. aureus lineages have been described in cases of necrotizing pneumonia worldwide, usually in young, previously healthy patients. In this work, we describe a fatal case of necrotizing pneumonia due to community-acquired methicillin-resistant S. aureus clone ST30-SCCmecIVc-spat019-PVL positive in an immunocompetent adult patient. Copyright © 2014 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Optimized chaotic Brillouin dynamic grating with filtered optical feedback.

Science.gov (United States)

Zhang, Jianzhong; Li, Zhuping; Wu, Yuan; Zhang, Mingjiang; Liu, Yi; Li, Mengwen

2018-01-16

Chaotic Brillouin dynamic gratings (BDGs) have special advantages such as the creation of single, permanent and localized BDG. However, the periodic signals induced by conventional optical feedback (COF) in chaotic semiconductor lasers can lead to the generation of spurious BDGs, which will limit the application of chaotic BDGs. In this paper, filtered optical feedback (FOF) is proposed to eliminate spurious BDGs. By controlling the spectral width of the optical filter and its detuning from the laser frequency, semiconductor lasers with FOF operate in the suppression region of the time-delay signature, and chaotic outputs serving as pump waves are then utilized to generate the chaotic BDG in a polarization maintaining fiber. Through comparative analysis of the COF and FOF schemes, it has been demonstrated that spurious BDGs are effectively eliminated and that the reflection characterization of the chaotic BDG is improved. The influence of FOF on the reflection and gain spectra of the chaotic BDG is analyzed as well.

Permanent magnets including undulators and wigglers

CERN Document Server

Bahrdt, J

2010-01-01

After a few historic remarks on magnetic materials we introduce the basic definitions related to permanent magnets. The magnetic properties of the most common materials are reviewed and the production processes are described. Measurement techniques for the characterization of macroscopic and microscopic properties of permanent magnets are presented. Field simulation techniques for permanent magnet devices are discussed. Today, permanent magnets are used in many fields. This article concentrates on the applications of permanent magnets in accelerators starting from dipoles and quadrupoles on to wigglers and undulators.

Marxism as permanent revolution

NARCIS (Netherlands)

van Ree, E.

2013-01-01

This article argues that the 'permanent revolution' represented the dominant element in Karl Marx and Friedrich Engels' political discourse, and that it tended to overrule considerations encapsulated in 'historical materialism'. In Marx and Engels's understanding, permanent revolution did not

Plasma grid design for optimized filter field configuration for the NBI test facility ELISE

International Nuclear Information System (INIS)

Nocentini, R.; Gutser, R.; Heinemann, B.; Froeschle, M.; Riedl, R.

2009-01-01

Maintenance-free RF sources for negative hydrogen ions with moderate extraction areas (100-200 cm 2 ) have been successfully developed in the last years at IPP Garching in the test facilities BATMAN and MANITU. A facility with larger extraction area (1000 cm 2 ), ELISE, is being designed with a 'half-size' ITER-like extraction system, pulsed ion acceleration up to 60 kV for 10 s and plasma generation up to 1 h. Due to the large size of the source, the magnetic filter field (FF) cannot be produced solely by permanent magnets. Therefore, an additional magnetic field produced by current flowing through the plasma grid (PG current) is required. The filter field homogeneity and the interaction with the electron suppression magnetic field have been studied in detail by finite element method (FEM) during the ELISE design phase. Significant improvements regarding the field homogeneity have been introduced compared to the ITER reference design. Also, for the same PG current a 50% higher field in front of the grid has been achieved by optimizing the plasma grid geometry. Hollow spaces have been introduced in the plasma grid for a more homogeneous PG current distribution. The introduction of hollow spaces also allows the insertion of permanent magnets in the plasma grid.

Should We Remove the Retrievable Cook Celect Inferior Vena Cava Filter? Eight Years of Experience at a Single Center

Directory of Open Access Journals (Sweden)

Joohyung Son

2017-12-01

Full Text Available Background: The inferior vena cava filter (IVCF is very effective for preventing pulmonary embolism in pa-tients who cannot undergo anticoagulation therapy. However, if a filter is placed in the body permanently, it may lead to other complications. Methods: A retrospective study was performed of 159 patients who under-went retrievable Cook Celect IVCF implantation between January 2007 and April 2015 at a single center. Baseline characteristics, indications, and complications caused by the filter were investigated. Results: The most common underlying disease of patients receiving the filter was cancer (24.3%. Venous thrombolysis or thrombectomy was the most common indication for IVCF insertion in this study (47.2%. The most common complication was inferior vena cava penetration, the risk of which increased the longer the filter remained in the body (p=0.032, Exp(B=1.004. Conclusion: If the patient is able to retry anticoagulation therapy and the filter is no longer needed, the filter should be removed, even if a long time has elapsed since implantation. If the filter cannot be removed, it is recommended that follow-up computed tomography be performed regularly to monitor the progress of venous thromboembolisms as well as any filter-related complications.

A Two-stage Kalman Filter for Sensorless Direct Torque Controlled PM Synchronous Motor Drive

Directory of Open Access Journals (Sweden)

Boyu Yi

2013-01-01

Full Text Available This paper presents an optimal two-stage extended Kalman filter (OTSEKF for closed-loop flux, torque, and speed estimation of a permanent magnet synchronous motor (PMSM to achieve sensorless DTC-SVPWM operation of drive system. The novel observer is obtained by using the same transformation as in a linear Kalman observer, which is proposed by C.-S. Hsieh and F.-C. Chen in 1999. The OTSEKF is an effective implementation of the extended Kalman filter (EKF and provides a recursive optimum state estimation for PMSMs using terminal signals that may be polluted by noise. Compared to a conventional EKF, the OTSEKF reduces the number of arithmetic operations. Simulation and experimental results verify the effectiveness of the proposed OTSEKF observer for DTC of PMSMs.

Nitinol Embolic Protection Filters: Design Investigation by Finite Element Analysis

Science.gov (United States)

Conti, Michele; de Beule, Matthieu; Mortier, Peter; van Loo, Denis; Verdonck, Pascal; Vermassen, Frank; Segers, Patrick; Auricchio, Ferdinando; Verhegghe, Benedict

2009-08-01

The widespread acceptance of carotid artery stenting (CAS) to treat carotid artery stenosis and its effectiveness compared with surgical counterpart, carotid endarterectomy (CEA), is still a matter of debate. Transient or permanent neurological deficits may develop in patients undergoing CAS due to distal embolization or hemodynamic changes. Design, development, and usage of embolic protection devices (EPDs), such as embolic protection filters, appear to have a significant impact on the success of CAS. Unfortunately, some drawbacks, such as filtering failure, inability to cross tortuous high-grade stenoses, malpositioning and vessel injury, still remain and require design improvement. Currently, many different designs of such devices are available on the rapidly growing dedicated market. In spite of such a growing commercial interest, there is a significant need for design tools as well as for careful engineering investigations and design analyses of such nitinol devices. The present study aims to investigate the embolic protection filter design by finite element analysis. We first developed a parametrical computer-aided design model of an embolic filter based on micro-CT scans of the Angioguard™ XP (Cordis Endovascular, FL) EPD by means of the open source pyFormex software. Subsequently, we used the finite element method to simulate the deployment of the nitinol filter as it exits the delivery sheath. Comparison of the simulations with micro-CT images of the real device exiting the catheter showed excellent correspondence with our simulations. Finally, we evaluated circumferential basket-vessel wall apposition of a 4 mm size filter in a straight vessel of different sizes and shape. We conclude that the proposed methodology offers a useful tool to evaluate and to compare current or new designs of EPDs. Further simulations will investigate vessel wall apposition in a realistic tortuous anatomy.

Permanent quadrupole magnets

International Nuclear Information System (INIS)

Bush, E.D. Jr.

1976-01-01

A family of quadrupole magnets using a soft iron return yoke and circular cross-section permanent magnet poles were fabricated to investigate the feasibility for use in ion or electron beam focusing applications in accelerators and transport lines. Magnetic field measurements yielded promising results. In fixed-field applications, permanent magnets with sufficient gradients would be a low cost substitute for conventional electromagnets, eliminating the need for power supplies, associated wiring, and cooling. (author)

Post-accident recirculation filters for fission product removal from the containment atmosphere

International Nuclear Information System (INIS)

Dillmann, H.G.; Pasler, H.

1975-01-01

The prototype post-accident recirculation filters have been subjected to further tests made under various conditions. The filter system exposed to hot air of 160 0 C and to saturated steam up to 1 atm and temperatures between 108 0 C and 160 0 C yielded for residence times of 0.2 sec after 18 days of permanent operation removal efficiencies > 99.98% for CH 3 J with a flow of 1,200 m 3 /h. Induced by previous experimental results the adsorber material was examined for transportation of the impregnation by the air-steam mixture. No measurable transportation was found (detection limit 0.6 x 10 -6 g Ag when 32 g of sorption material were used) under different conditions up to temperatures of 200 0 C in superheated steam over a duration of the experiment of 48 h. (orig.) [de

Sensory Pollution from Bag Filters, Carbon Filters and Combinations

DEFF Research Database (Denmark)

Bekö, Gabriel; Clausen, Geo; Weschler, Charles J.

2008-01-01

by an upstream pre-filter (changed monthly), an EU7 filter protected by an upstream activated carbon (AC) filter, and EU7 filters with an AC filter either downstream or both upstream and downstream. In addition, two types of stand-alone combination filters were evaluated: a bag-type fiberglass filter...... that contained AC and a synthetic fiber cartridge filter that contained AC. Air that had passed through used filters was most acceptable for those sets in which an AC filter was used downstream of the particle filter. Comparable air quality was achieved with the stand-alone bag filter that contained AC...

Safety and Efficacy of the Gunther Tulip Retrievable Vena Cava Filter: Midterm Outcomes

International Nuclear Information System (INIS)

Hoffer, Eric K.; Mueller, Rebecca J.; Luciano, Marcus R.; Lee, Nicole N.; Michaels, Anne T.; Gemery, John M.

2013-01-01

PurposeTo evaluate of the medium-term integrity, efficacy, and complication rate associated with the Gunther Tulip vena cava filter.MethodsA retrospective study was performed of 369 consecutive patients who had infrarenal Gunther Tulip inferior vena cava filters placed over a 5-year period. The mean patient age was 61.8 years, and 59 % were men. Venous thromboembolic disease and a contraindication to or complication of anticoagulation were the indications for filter placement in 86 % of patients; 14 % were placed for prophylaxis in patients with a mean of 2.3 risk factors. Follow-up was obtained by review of medical and radiologic records.ResultsMean clinical follow-up was 780 days. New or recurrent pulmonary embolus occurred in 12 patients (3.3 %). New or recurrent deep-vein thrombosis occurred in 53 patients (14.4 %). There were no symptomatic fractures, migrations, or caval perforations. Imaging follow-up in 287 patients (77.8 %) at a mean of 731 days revealed a single (0.3 %) asymptomatic fracture, migration greater than 2 cm in 36 patients (12.5 %), and no case of embolization. Of 122 patients with CT scans, asymptomatic perforations were identified in 53 patients (43.4 %) at a mean 757 days.ConclusionThe Gunther Tulip filter was safe and effective at 2-year follow-up. Complication rates were similar to those reported for permanent inferior vena cava filters

Safety and Efficacy of the Gunther Tulip Retrievable Vena Cava Filter: Midterm Outcomes

Energy Technology Data Exchange (ETDEWEB)

Hoffer, Eric K., E-mail: eric.k.hoffer@hitchcock.org; Mueller, Rebecca J.; Luciano, Marcus R.; Lee, Nicole N.; Michaels, Anne T.; Gemery, John M. [Dartmouth-Hitchcock Medical Center, Department of Radiology, Section of Vascular and Interventional Radiology (United States)

2013-08-01

PurposeTo evaluate of the medium-term integrity, efficacy, and complication rate associated with the Gunther Tulip vena cava filter.MethodsA retrospective study was performed of 369 consecutive patients who had infrarenal Gunther Tulip inferior vena cava filters placed over a 5-year period. The mean patient age was 61.8 years, and 59 % were men. Venous thromboembolic disease and a contraindication to or complication of anticoagulation were the indications for filter placement in 86 % of patients; 14 % were placed for prophylaxis in patients with a mean of 2.3 risk factors. Follow-up was obtained by review of medical and radiologic records.ResultsMean clinical follow-up was 780 days. New or recurrent pulmonary embolus occurred in 12 patients (3.3 %). New or recurrent deep-vein thrombosis occurred in 53 patients (14.4 %). There were no symptomatic fractures, migrations, or caval perforations. Imaging follow-up in 287 patients (77.8 %) at a mean of 731 days revealed a single (0.3 %) asymptomatic fracture, migration greater than 2 cm in 36 patients (12.5 %), and no case of embolization. Of 122 patients with CT scans, asymptomatic perforations were identified in 53 patients (43.4 %) at a mean 757 days.ConclusionThe Gunther Tulip filter was safe and effective at 2-year follow-up. Complication rates were similar to those reported for permanent inferior vena cava filters.

Safety and efficacy of the Gunther Tulip retrievable vena cava filter: midterm outcomes.

Science.gov (United States)

Hoffer, Eric K; Mueller, Rebecca J; Luciano, Marcus R; Lee, Nicole N; Michaels, Anne T; Gemery, John M

2013-08-01

To evaluate of the medium-term integrity, efficacy, and complication rate associated with the Gunther Tulip vena cava filter. A retrospective study was performed of 369 consecutive patients who had infrarenal Gunther Tulip inferior vena cava filters placed over a 5-year period. The mean patient age was 61.8 years, and 59% were men. Venous thromboembolic disease and a contraindication to or complication of anticoagulation were the indications for filter placement in 86% of patients; 14% were placed for prophylaxis in patients with a mean of 2.3 risk factors. Follow-up was obtained by review of medical and radiologic records. Mean clinical follow-up was 780 days. New or recurrent pulmonary embolus occurred in 12 patients (3.3%). New or recurrent deep-vein thrombosis occurred in 53 patients (14.4%). There were no symptomatic fractures, migrations, or caval perforations. Imaging follow-up in 287 patients (77.8%) at a mean of 731 days revealed a single (0.3%) asymptomatic fracture, migration greater than 2 cm in 36 patients (12.5%), and no case of embolization. Of 122 patients with CT scans, asymptomatic perforations were identified in 53 patients (43.4%) at a mean 757 days. The Gunther Tulip filter was safe and effective at 2-year follow-up. Complication rates were similar to those reported for permanent inferior vena cava filters.

Study on the diagnostic value of determination of serum IV-C, PC III, HA, LN and PLD concentrations for hepatic fibrosis in patients with B hepatitis of various types

International Nuclear Information System (INIS)

Li Zhuocheng; Chen Jianxiong; Xiong Ying

2004-01-01

Objective: To investigate the changes of serum levels of collagen type IV(IV-C), procollagen type III (PC III), hyaluronic acid (HA), laminin (LN) and prolidase (PLD) and their relationship with hepatic fibrosis in patients with B hepatitis of different types. Methods: Serum levels of IV-C, PC III, HA, LN and PLD were measured with RIA in 39 controls and 103 patients with HBV infection of various types (including acute hepatitis AH n=19, chronic persistent hepatitis CPH n=29, Chronic active hepatitis CAH n=25 and liver cirrhosis LH n=30. Degree of hepatic fibrosis (Grade 0-4) was ascertained with liver biopsy in 35 patients (CAH16, LC19) and correlationship with the corresponding levels of these 5 serum markers was steadied. Results: 1) Serum levels of IV-C, PC III, HA, LN and PLD were significantly higher in patients with CAH and LC than those in other patients and controls (P 0.05). 3) Serum levels of these markers were all positively correlated with the degree of hepatic fibrosis noted in the biopsy specimens obtained from patients with CAH (n=16) and LC (n=19) (r=+0.64 - + 0.89, P<0.01). Conclusion: Serum levels of these markers could reflect the degree of hepatic fibrosis and severity of liver damage; determination of which was of diagnostic and even prognostic value. HA and LN appeared to be better correlated with degree of hepatic fibrosis than the remaining three markers did. (authors)

The permanent NdFeB magnets in the circuits for magnetic filters and the first technological tests

Czech Academy of Sciences Publication Activity Database

Žežulka, Václav; Straka, Pavel; Mucha, Pavel

2005-01-01

Roč. 78, - (2005), s. 31-39 ISSN 0301-7516 R&D Projects: GA AV ČR IBS3046004 Institutional research plan: CEZ:AV0Z30460519 Keywords : magnetic circuit * magnetic filter * rare earth magnets ( NdFeB ) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.965, year: 2005

31 CFR 515.335 - Permanent resident alien.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Permanent resident alien. 515.335... Definitions § 515.335 Permanent resident alien. As used in § 515.208, the term permanent resident alien means an alien lawfully admitted for permanent residence into the United States. [61 FR 37386, July 18...

Lawful Permanent Residents - Annual Report

Data.gov (United States)

Department of Homeland Security — A lawful permanent resident (LPR) or 'green card' recipient is defined by immigration law as a person who has been granted lawful permanent residence in the United...

Dataset on the spent filter backwash water treatment by sedimentation, coagulation and ultra filtration

OpenAIRE

Mokhtar Mahdavi; Afshin Ebrahimi; Hossein Azarpira; Hamid Reza Tashauoei; Amir Hossein Mahvi

2017-01-01

During operation of most water treatment plants, spent filter backwash water (SFBW) is generated, which accounts about 2â10% of the total plant production. By increasing world population and water shortage in many countries, SFBW can be used as a permanent water source until the water treatment plant is working. This data article reports the practical method being used for water reuse from SFBW through different method including pre-sedimentation, coagulation and flocculation, second clarific...

21 CFR 886.4445 - Permanent magnet.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Permanent magnet. 886.4445 Section 886.4445 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4445 Permanent magnet. (a) Identification. A permanent magnet is a nonelectric device that generates a magnetic field intended to find and remove metallic...

Filter arrays

Science.gov (United States)

Page, Ralph H.; Doty, Patrick F.

2017-08-01

The various technologies presented herein relate to a tiled filter array that can be used in connection with performance of spatial sampling of optical signals. The filter array comprises filter tiles, wherein a first plurality of filter tiles are formed from a first material, the first material being configured such that only photons having wavelengths in a first wavelength band pass therethrough. A second plurality of filter tiles is formed from a second material, the second material being configured such that only photons having wavelengths in a second wavelength band pass therethrough. The first plurality of filter tiles and the second plurality of filter tiles can be interspersed to form the filter array comprising an alternating arrangement of first filter tiles and second filter tiles.

[Permanent education in health: a review].

Science.gov (United States)

Miccas, Fernanda Luppino; Batista, Sylvia Helena Souza da Silva

2014-02-01

To undertake a meta-synthesis of the literature on the main concepts and practices related to permanent education in health. A bibliographical search was conducted for original articles in the PubMed, Web of Science, LILACS, IBECS and SciELO databases, using the following search terms: "public health professional education", "permanent education", "continuing education", "permanent education health". Of the 590 articles identified, after applying inclusion and exclusion criteria, 48 were selected for further analysis, grouped according to the criteria of key elements, and then underwent meta-synthesis. The 48 original publications were classified according to four thematic units of key elements: 1) concepts, 2) strategies and difficulties, 3) public policies and 4) educational institutions. Three main conceptions of permanent education in health were found: problem-focused and team work, directly related to continuing education and education that takes place throughout life. The main strategies for executing permanent education in health are discussion, maintaining an open space for permanent education , and permanent education clusters. The most limiting factor is mainly related to directly or indirect management. Another highlight is the requirement for implementation and maintenance of public policies, and the availability of financial and human resources. The educational institutions need to combine education and service aiming to form critical-reflexive graduates. The coordination between health and education is based as much on the actions of health services as on management and educational institutions. Thus, it becomes a challenge to implement the teaching-learning processes that are supported by critical-reflexive actions. It is necessary to carry out proposals for permanent education in health involving the participation of health professionals, teachers and educational institutions. To undertake a meta-synthesis of the literature on the main concepts and

Periodic permanent magnet focused klystron

Science.gov (United States)

Ferguson, Patrick; Read, Michael; Ives, R Lawrence

2015-04-21

A periodic permanent magnet (PPM) klystron has beam transport structures and RF cavity structures, each of which has permanent magnets placed substantially equidistant from a beam tunnel formed about the central axis, and which are also outside the extent of a cooling chamber. The RF cavity sections also have permanent magnets which are placed substantially equidistant from the beam tunnel, but which include an RF cavity coupling to the beam tunnel for enhancement of RF carried by an electron beam in the beam tunnel.

Evaluation of spontaneous space closure and development of permanent dentition after extraction of hypomineralized permanent first molars.

Science.gov (United States)

Jälevik, Birgitta; Möller, Marie

2007-09-01

The aim of this study was to evaluate spontaneous space closure, development of the permanent dentition, and need for orthodontic treatment after extraction of permanent first molars due to severe molar-incisor hypomineralization (MIH). Twenty-seven children aged 5.6-12.7 (median 8.2) years had one to four permanent first molars extracted due to severe MIH. Each case was followed up on individual indications 3.8-8.3 (median 5.7) years after extractions. The eruption of the permanent dentition, and space closure were documented by orthopantomograms, casts, photographs, and/or bitewings. Fifteen children were judged to have a favourable spontaneous development of their permanent dentition without any orthodontic intervention. Seven children were or should be subjected to orthodontic treatment for other reasons registered prior to the extraction. Five children were judged to have a treatment at least caused by the extractions, but three of them abstained because of no subjective treatment need. Extraction of permanent first molars severely affected by MIH is a good treatment alternative. Favourable spontaneous space reduction and development of the permanent dentition positioning can be expected without any intervention in the majority of cases extracted prior to the eruption of the second molar.

Modern permanent magnetic materials - preparation and properties

International Nuclear Information System (INIS)

Rodewald, W.

1989-01-01

First of all, the basic properties of the classical (steel, AlNiCo) permanent magnetic materials and the modern rare-earth (RE) permanent magnetic materials are compared. Since the properties of RE permanent magnets depend on the particular production process, the fundamentals of the main industrial processes (powder metallurgy, rapid-solidification technique) are described and the typical properties are explained. Furthermore the production processes in development such as mechanical alloying, melt spinning technique and extrusion upsetting are briefly outlined. For applying the permanent magnets, they have to be completely magnetized. The magnetization behaviour of the various RE permanent magnets is discussed by means of the internal demagnetization curve. Finally the various influences on the temperature stability of RE permanent magnets are compiled. (orig./MM) [de

Lawful Permanent Residents Fiscal Year 2015 State

Data.gov (United States)

Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

Lawful Permanent Residents Fiscal Year 2014 Country

Data.gov (United States)

Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

Lawful Permanent Residents Fiscal Year 2011 State

Data.gov (United States)

Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

Lawful Permanent Residents Fiscal Year 2015 Country

Data.gov (United States)

Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

Lawful Permanent Residents Fiscal Year 2016 State

Data.gov (United States)

Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

Lawful Permanent Residents Fiscal Year 2014 State

Data.gov (United States)

Department of Homeland Security — Lawful permanent residents (LPRs) are foreign nationals who have been granted the right to reside permanently in the United States. LPRs are also known as 'permanent...

Digital Simulation of a Hybrid Active Filter - An Active Filter in Series with a Shunt Passive Filter

OpenAIRE

Sitaram, Mahesh I; Padiyar, KR; Ramanarayanan, V

1998-01-01

Active filters have long been in use for the filtering of power system load harmonics. In this paper, the digital simulation results of a hybrid active power filter system for a rectifier load are presented. The active filter is used for filtering higher order harmonics as the dominant harmonics are filtered by the passive filter. This reduces the rating of the active filter significantly. The DC capacitor voltage of the active filter is controlled using a PI controller.

Topology optimized permanent magnet systems

DEFF Research Database (Denmark)

Bjørk, Rasmus; Bahl, Christian; Insinga, Andrea Roberto

2017-01-01

Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. The Halbach cylinder is topology optimized with iron...... and an increase of 15% in magnetic efficiency is shown. A topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111%. Finally, a permanent magnet with alternating high and low field regions is topology optimized and a ΛcoolΛcool figure of merit of 0...

Object permanence in lemurs.

Science.gov (United States)

Deppe, Anja M; Wright, Patricia C; Szelistowski, William A

2009-03-01

Object permanence, the ability to mentally represent objects that have disappeared from view, should be advantageous to animals in their interaction with the natural world. The objective of this study was to examine whether lemurs possess object permanence. Thirteen adult subjects representing four species of diurnal lemur (Eulemur fulvus rufus, Eulemur mongoz, Lemur catta and Hapalemur griseus) were presented with seven standard Piagetian visible and invisible object displacement tests, plus one single visible test where the subject had to wait predetermined times before allowed to search, and two invisible tests where each hiding place was made visually unique. In all visible tests lemurs were able to find an object that had been in clear view before being hidden. However, when lemurs were not allowed to search for up to 25-s, performance declined with increasing time-delay. Subjects did not outperform chance on any invisible displacements regardless of whether hiding places were visually uniform or unique, therefore the upper limit of object permanence observed was Stage 5b. Lemur species in this study eat stationary foods and are not subject to stalking predators, thus Stage 5 object permanence is probably sufficient to solve most problems encountered in the wild.

Animal experimental study of safety for a self-made vena cava stent-filter

International Nuclear Information System (INIS)

Qin Dingwen; Shi Haibin; Liu Sheng; Li Linsun

2008-01-01

Objective: To evaluate the safety of a self-made vena cava stent-filter(VCSF)for prevention of pulmonary embolism. Methods: Fusiform unmhrella-like vena cava filter was made of Nitinol wires and stainless steel metal pole, and then ten mongrel dogs were implanted with these self-made filters and divided into 5 groups according to the different periods (2, 3, 4, 5 and 6 w) of filter placement, with 2 dogs in each group. After the VCSFs were placed in inferior vena cava via the right femoral vein approach, the dogs in each group were bred for 2-6 weeks, respectively. The blood flow of inferior vena cava and the position of the filters were inspected by inferior vena-cavography according to the indwelling periods. Finally the metal pole was retrieved via the femoral vein, leaving the VCSF as permanent venousz stent. The feasibility of retrieval and the free state of filter net with the adhering vascular wall were evaluated. Laparotomies were performed to remove the inferior vena cava from the animals for gross and electron microscopic examinations of the inferior vena cava intimal changes of the involved segment. Results: All 10 VCSFs were placed at the right positions of the dogs successfully. Angiography showed patent inferior vena cava without filter thrombosis at 2-6 weeks. There were no tilting and migration of the filter and all the metal poles were successfully retrieved. The superior and inferior extremities of filter nets could be set free with all the filters turning into venous stents. Postmortem displayed retroperitoneal hemorrhage and caval thrombosis. The barbs of the filters penetrated over the caval adventitial coat. Under electron microscope, a thin layer of neointima already covered the braiding net of VCSFs at 2 weeks after the deployment. The tunica intima became slightly thick at 3-4 weeks and with moderate proliferation at 5-6 weeks. Conclusions: The self-made vena cava stent-filter possesses rather long indwelling period according to the

Filter assembly for metallic and intermetallic tube filters

Science.gov (United States)

Alvin, Mary Anne; Lippert, Thomas E.; Bruck, Gerald J.; Smeltzer, Eugene E.

2001-01-01

A filter assembly (60) for holding a filter element (28) within a hot gas cleanup system pressure vessel is provided, containing: a filter housing (62), said filter housing having a certain axial length and having a peripheral sidewall, said sidewall defining an interior chamber (66); a one piece, all metal, fail-safe/regenerator device (68) within the interior chamber (66) of the filter housing (62) and/or extending beyond the axial length of the filter housing, said device containing an outward extending radial flange (71) within the filter housing for seating an essential seal (70), the device also having heat transfer media (72) disposed inside and screens (80) for particulate removal; one compliant gasket (70) positioned next to and above the outward extending radial flange of the fail-safe/regenerator device; and a porous metallic corrosion resistant superalloy type filter element body welded at the bottom of the metal fail-safe/regenerator device.

Marxism as permanent revolution

OpenAIRE

van Ree, E.

2013-01-01

This article argues that the 'permanent revolution' represented the dominant element in Karl Marx and Friedrich Engels' political discourse, and that it tended to overrule considerations encapsulated in 'historical materialism'. In Marx and Engels's understanding, permanent revolution did not represent a historical shortcut under exceptional circumstances, but the course revolutions in the modern era would normally take. Marx and Engels traced back the pattern to the sixteenth century. It is ...

Statistically-Efficient Filtering in Impulsive Environments: Weighted Myriad Filters

Directory of Open Access Journals (Sweden)

Juan G. Gonzalez

2002-01-01

Full Text Available Linear filtering theory has been largely motivated by the characteristics of Gaussian signals. In the same manner, the proposed Myriad Filtering methods are motivated by the need for a flexible filter class with high statistical efficiency in non-Gaussian impulsive environments that can appear in practice. Myriad filters have a solid theoretical basis, are inherently more powerful than median filters, and are very general, subsuming traditional linear FIR filters. The foundation of the proposed filtering algorithms lies in the definition of the myriad as a tunable estimator of location derived from the theory of robust statistics. We prove several fundamental properties of this estimator and show its optimality in practical impulsive models such as the α-stable and generalized-t. We then extend the myriad estimation framework to allow the use of weights. In the same way as linear FIR filters become a powerful generalization of the mean filter, filters based on running myriads reach all of their potential when a weighting scheme is utilized. We derive the “normal” equations for the optimal myriad filter, and introduce a suboptimal methodology for filter tuning and design. The strong potential of myriad filtering and estimation in impulsive environments is illustrated with several examples.

Filter material charging apparatus for filter assembly for radioactive contaminants

International Nuclear Information System (INIS)

Goldsmith, J.M.; O'Nan, A. Jr.

1977-01-01

A filter charging apparatus for a filter assembly is described. The filter assembly includes a housing with at least one filter bed therein and the filter charging apparatus for adding filter material to the filter assembly includes a tank with an opening therein, the tank opening being disposed in flow communication with opposed first and second conduit means, the first conduit means being in flow communication with the filter assembly housing and the second conduit means being in flow communication with a blower means. Upon activation of the blower means, the blower means pneumatically conveys the filter material from the tank to the filter housing

Canadian Eskimo permanent tooth emergence timing.

Science.gov (United States)

Mayhall, J T; Belier, P L; Mayhall, M F

1978-08-01

To identify the times of emergence of the permanent teeth of Canadian Eskimos (Inuit), 368 children and adolescents were examined. The presence or absence of all permanent teeth except the third molars was recorded and these data subjected to probit analysis. Female emergence times were advanced over males. Generally, the Inuit of both sexes showed statistically significant earlier emergence times than Montreal children, except for the incisors. The present results do not support hypotheses indicating that premature extraction of the deciduous teeth advances the emergence of their succedaneous counterparts. There is some indication the controls of deciduous tooth emergence continue to play some part in emergence of the permanent dentition, especially the first permanent teeth that emerge.

13 CFR 120.900 - Sources of permanent financing.

Science.gov (United States)

2010-01-01

... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Sources of permanent financing... Development Company Loan Program (504) Permanent Financing § 120.900 Sources of permanent financing. Permanent financing for each Project must come from three sources: the Borrower's contribution, Third-Party Loans, and...

[The Object Permanence Fallacy.] Commentary.

Science.gov (United States)

Bradley, Ben S.

1996-01-01

Suggests that Greenberg's challenge to the centrality of object permanence in developmental thinking reveals that developmentalists' theories about childhood speak about their own self-images. Notes that developmentalists have been guilty of not only the object permanence fallacy but also the genetic fallacy, or the mistaken belief that describing…

Non anti-coagulant factors associated with filter life in continuous renal replacement therapy (CRRT): a systematic review and meta-analysis.

Science.gov (United States)

Brain, Matthew; Winson, Elizabeth; Roodenburg, Owen; McNeil, John

2017-02-20

Optimising filter life and performance efficiency in continuous renal replacement therapy has been a focus of considerable recent research. Larger high quality studies have predominantly focussed on optimal anticoagulation however CRRT is complex and filter life is also affected by vascular access, circuit and management factors. We performed a systematic search of the literature to identify and quantify the effect of vascular access, circuit and patient factors that affect filter life and presented the results as a meta-analysis. A systematic review and meta-analysis was performed by searching Pubmed (MEDLINE) and Ovid EMBASE libraries from inception to 29 th February 2016 for all studies with a comparator or independent variable relating to CRRT circuits and reporting filter life. Included studies documented filter life in hours with a comparator other than anti-coagulation intervention. All studies comparing anticoagulation interventions were searched for regression or hazard models pertaining to other sources of variation in filter life. Eight hundred nineteen abstracts were identified of which 364 were selected for full text analysis. 24 presented data on patient modifiers of circuit life, 14 on vascular access modifiers and 34 on circuit related factors. Risk of bias was high and findings are hypothesis generating. Ranking of vascular access site by filter longevity favours: tunnelled semi-permanent catheters, femoral, internal jugular and subclavian last. There is inconsistency in the difference reported between femoral and jugular catheters. Amongst published literature, modality of CRRT consistently favoured continuous veno-venous haemodiafiltration (CVVHD-F) with an associated 44% lower failure rate compared to CVVH. There was a trend favouring higher blood flow rates. There is insufficient data to determine advantages of haemofilter membranes. Patient factors associated with a statistically significant worsening of filter life included mechanical

Topology optimized permanent magnet systems

Science.gov (United States)

Bjørk, R.; Bahl, C. R. H.; Insinga, A. R.

2017-09-01

Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. The Halbach cylinder is topology optimized with iron and an increase of 15% in magnetic efficiency is shown. A topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111%. Finally, a permanent magnet with alternating high and low field regions is topology optimized and a Λcool figure of merit of 0.472 is reached, which is an increase of 100% compared to a previous optimized design.

Teaching Object Permanence: An Action Research Study

Science.gov (United States)

Bruce, Susan M.; Vargas, Claudia

2013-01-01

"Object permanence," also known as "object concept" in the field of visual impairment, is one of the most important early developmental milestones. The achievement of object permanence is associated with the onset of representational thought and language. Object permanence is important to orientation, including the recognition of landmarks.…

Intrusive luxation of 60 permanent incisors

DEFF Research Database (Denmark)

Tsilingaridis, Georgios; Malmgren, Barbro; Andreasen, Jens O

2012-01-01

  Intrusive luxation in the permanent dentition is an uncommon injury but it is considered one of the most severe types of dental trauma because of the risk for damage to the periodontal ligament, pulp and alveolar bone. Management of intrusive luxation in the permanent dentition is controversial....... The purpose of this study was to evaluate pulp survival and periodontal healing in intrusive luxated permanent teeth in relation to treatment alternatives, degree of intrusion and root development....

ADAPTIVE FLUX OBSERVER FOR PERMANENT MAGNET SYNCHRONOUS MOTORS

Directory of Open Access Journals (Sweden)

A. A. Bobtsov

2015-01-01

Full Text Available The paper deals with the observer design problem for a flux in permanent magnet synchronous motors. It is assumed that some electrical parameters such as resistance and inductance are known numbers. But the flux, the angle and the speed of the rotor are unmeasurable. The new robust approach to design an adaptive flux observer is proposed that guarantees globally boundedness of all signals and, moreover, exponential convergence to zero of observer error between the true flux value and an estimate obtained from the adaptive observer. The problem of an adaptive flux observer design has been solved with using the trigonometrical properties and linear filtering which ensures cancellation of unknown terms arisen after mathematical calculations. The key idea is the new parameterization of the dynamical model containing unknown parameters and depending on measurable current and voltage in the motor. By applying the Pythagorean trigonometric identity the linear equation has found that does not contain any functions depending on angle or angular velocity of the rotor. Using dynamical first-order filters the standard regression model is obtained that consists of unknown constant parameters and measurable functions of time. Then the gradient-like estimator is designed to reconstruct unknown parameters, and it guarantees boundedness of all signals in the system. The proposition is proved that if the regressor satisfies the persistent excitation condition, meaning the “frequency-rich” signal, then all errors in observer exponentially converges to zero. It is shown that observer error for the flux explicitly depends on estimator errors. Exponential convergence of parameter estimation errors to zero yields exponential convergence of the flux observer error to zero. The numerical example is considered.

Permanent magnet materials and their application

International Nuclear Information System (INIS)

Campbell, P.

1994-01-01

Permanent magnets are of great industrial importance in industrial drives, consumer products, computers, and automobiles. Since 1970, new classes of magnet materials have been developed. This book reviews the older and newer materials and is presented as a comprehensive design text for permanent magnets and their applications. After an initial chapter on the fundamentals of magnetism, the author discusses magnetic physics considerations specific to permanent magnets and describes the fabrications and characteristics of commercial materials: alnico, samarium-cobalt, ferrite, and neodymium-iron-boron. Thermal stability, magnet design procedures, magnetic field analysis methods, and measurement methods are discussed in subsequent chapters, followed by a concluding chapter reviewing commercial and industrial products that use permanent magnets. The chapter on thermal properties of magnet materials is of particular interest, bringing together information not readily found elsewhere. The review of applications is also deserving of attention, specifically the sections on motors and actuators. Although particle accelerator applications are discussed, the use of permanent magnet sextuples in modern ECR ion sources is not mentioned

Experimental study of filter cake formation on different filter media

International Nuclear Information System (INIS)

Saleem, M.

2009-01-01

Removal of particulate matter from gases generated in the process industry is important for product recovery as well as emission control. Dynamics of filtration plant depend on operating conditions. The models, that predict filter plant behaviour, involve empirical resistance parameters which are usually derived from limited experimental data and are characteristics of the filter media and filter cake (dust deposited on filter medium). Filter cake characteristics are affected by the nature of filter media, process parameters and mode of filter regeneration. Removal of dust particles from air is studied in a pilot scale jet pulsed bag filter facility resembling closely to the industrial filters. Limestone dust and ambient air are used in this study with two widely different filter media. All important parameters like pressure drop, gas flow rate, dust settling, are recorded continuously at 1s interval. The data is processed for estimation of the resistance parameters. The pressure drop rise on test filter media is compared. Results reveal that the surface of filter media has an influence on pressure drop rise (concave pressure drop rise). Similar effect is produced by partially jet pulsed filter surface. Filter behaviour is also simulated using estimated parameters and a simplified model and compared with the experimental results. Distribution of cake area load is therefore an important aspect of jet pulse cleaned bag filter modeling. Mean specific cake resistance remains nearly constant on thoroughly jet pulse cleaned membrane coated filter bags. However, the trend can not be confirmed without independent cake height and density measurements. Thus the results reveal the importance of independent measurements of cake resistance. (author)

MST Filterability Tests

Energy Technology Data Exchange (ETDEWEB)

Poirier, M. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Burket, P. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Duignan, M. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2015-03-12

The Savannah River Site (SRS) is currently treating radioactive liquid waste with the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Extraction Unit (MCU). The low filter flux through the ARP has limited the rate at which radioactive liquid waste can be treated. Recent filter flux has averaged approximately 5 gallons per minute (gpm). Salt Batch 6 has had a lower processing rate and required frequent filter cleaning. Savannah River Remediation (SRR) has a desire to understand the causes of the low filter flux and to increase ARP/MCU throughput. In addition, at the time the testing started, SRR was assessing the impact of replacing the 0.1 micron filter with a 0.5 micron filter. This report describes testing of MST filterability to investigate the impact of filter pore size and MST particle size on filter flux and testing of filter enhancers to attempt to increase filter flux. The authors constructed a laboratory-scale crossflow filter apparatus with two crossflow filters operating in parallel. One filter was a 0.1 micron Mott sintered SS filter and the other was a 0.5 micron Mott sintered SS filter. The authors also constructed a dead-end filtration apparatus to conduct screening tests with potential filter aids and body feeds, referred to as filter enhancers. The original baseline for ARP was 5.6 M sodium salt solution with a free hydroxide concentration of approximately 1.7 M.3 ARP has been operating with a sodium concentration of approximately 6.4 M and a free hydroxide concentration of approximately 2.5 M. SRNL conducted tests varying the concentration of sodium and free hydroxide to determine whether those changes had a significant effect on filter flux. The feed slurries for the MST filterability tests were composed of simple salts (NaOH, NaNO₂, and NaNO₃) and MST (0.2 – 4.8 g/L). The feed slurry for the filter enhancer tests contained simulated salt batch 6 supernate, MST, and filter enhancers.

Numerical study of canister filters with alternatives filter cap configurations

Science.gov (United States)

Mohammed, A. N.; Daud, A. R.; Abdullah, K.; Seri, S. M.; Razali, M. A.; Hushim, M. F.; Khalid, A.

2017-09-01

Air filtration system and filter play an important role in getting a good quality air into turbo machinery such as gas turbine. The filtration system and filter has improved the quality of air and protect the gas turbine part from contaminants which could bring damage. During separation of contaminants from the air, pressure drop cannot be avoided but it can be minimized thus helps to reduce the intake losses of the engine [1]. This study is focused on the configuration of the filter in order to obtain the minimal pressure drop along the filter. The configuration used is the basic filter geometry provided by Salutary Avenue Manufacturing Sdn Bhd. and two modified canister filter cap which is designed based on the basic filter model. The geometries of the filter are generated by using SOLIDWORKS software and Computational Fluid Dynamics (CFD) software is used to analyse and simulates the flow through the filter. In this study, the parameters of the inlet velocity are 0.032 m/s, 0.063 m/s, 0.094 m/s and 0.126 m/s. The total pressure drop produce by basic, modified filter 1 and 2 is 292.3 Pa, 251.11 Pa and 274.7 Pa. The pressure drop reduction for the modified filter 1 is 41.19 Pa and 14.1% lower compared to basic filter and the pressure drop reduction for modified filter 2 is 17.6 Pa and 6.02% lower compared to the basic filter. The pressure drops for the basic filter are slightly different with the Salutary Avenue filter due to limited data and experiment details. CFD software are very reliable in running a simulation rather than produces the prototypes and conduct the experiment thus reducing overall time and cost in this study.

Passive wide spectrum harmonic filter for adjustable speed drives in oil and gas industry

Science.gov (United States)

Al Jaafari, Khaled Ali

Non-linear loads such as variable speed drives constitute the bulky load of oil and gas industry power systems. They are widely used in driving induction and permanent magnet motors for variable speed applications. That is because variable speed drives provide high static and dynamic performance. Moreover, they are known of their high energy efficiency and high motion quality, and high starting torque. However, these non-linear loads are main sources of current and voltage harmonics and lower the quality of electric power system. In fact, it is the six-pulse and twelve-pulse diode and thyristor rectifiers that spoil the AC power line with the dominant harmonics (5th, 7th, 11th). They provide DC voltage to the inverter of the variable speed drives. Typical problems that arise from these harmonics are Harmonic resonances', harmonic losses, interference with electronic equipment, and line voltage distortion at the Point of Common Coupling (PCC). Thus, it is necessary to find efficient, reliable, and economical harmonic filters. The passive filters have definite advantage over active filters in terms of components count, cost and reliability. Reliability and maintenance is a serious issue in drilling rigs which are located in offshore and onshore with extreme operating conditions. Passive filters are tuned to eliminate a certain frequency and therefore there is a need to equip the system with more than one passive filter to eliminate all unwanted frequencies. An alternative solution is Wide Spectrum Harmonic passive filter. The wide spectrum harmonic filters are becoming increasingly popular in these applications and found to overcome some of the limitations of conventional tuned passive filter. The most important feature of wide spectrum harmonic passive filters is that only one capacitor is required to filter a wide range of harmonics. Wide spectrum filter is essentially a low-pass filter for the harmonic at fundamental frequency. It can also be considered as a

Social and Demographic Factors Influencing Inferior Vena Cava Filter Retrieval at a Single Institution in the United States

Energy Technology Data Exchange (ETDEWEB)

Smith, S. Christian, E-mail: csmith@aemrc.arizona.edu; Shanks, Candace, E-mail: Candace.Shanks@osumc.edu; Guy, Gregory, E-mail: Gregory.Guy@osumc.edu; Yang, Xiangyu, E-mail: Xiangyu.Yang@osumc.edu; Dowell, Joshua D., E-mail: Joshua.Dowell@osumc.edu [The Ohio State University Wexner Medical Center, Division of Interventional Radiology, Department of Radiology (United States)

2015-10-15

PurposeRetrievable inferior vena cava filters (IVCFs) are associated with long-term adverse events that have increased interest in improving filter retrieval rates. Determining the influential patient social and demographic factors affecting IVCF retrieval is important to personalize patient management strategies and attain optimal patient care.Materials and MethodsSeven-hundred and sixty-two patients were retrospectively studied who had a filter placed at our institution between January 2011 and November 2013. Age, gender, race, cancer history, distance to residence from retrieval institution, and insurance status were identified for each patient, and those receiving retrievable IVCFs were further evaluated for retrieval rate and time to retrieval.ResultsOf the 762 filters placed, 133 were permanent filters. Of the 629 retrievable filters placed, 406 met the inclusion criteria and were eligible for retrieval. Results revealed patients with Medicare were less likely to have their filters retrieved (p = 0.031). Older age was also associated with a lower likelihood of retrieval (p < 0.001) as was living further from the medical center (p = 0.027). Patients who were white and had Medicare were more likely than similarly insured black patients to have their filters retrieved (p = 0.024).ConclusionsThe retrieval rate of IVCFs was most influenced by insurance status, distance from the medical center, and age. Race was statistically significant only when combined with insurance status. The results of this study suggest that these patient groups may need closer follow-up in order to obtain optimal IVCF retrieval rates.

Social and Demographic Factors Influencing Inferior Vena Cava Filter Retrieval at a Single Institution in the United States

International Nuclear Information System (INIS)

Smith, S. Christian; Shanks, Candace; Guy, Gregory; Yang, Xiangyu; Dowell, Joshua D.

2015-01-01

PurposeRetrievable inferior vena cava filters (IVCFs) are associated with long-term adverse events that have increased interest in improving filter retrieval rates. Determining the influential patient social and demographic factors affecting IVCF retrieval is important to personalize patient management strategies and attain optimal patient care.Materials and MethodsSeven-hundred and sixty-two patients were retrospectively studied who had a filter placed at our institution between January 2011 and November 2013. Age, gender, race, cancer history, distance to residence from retrieval institution, and insurance status were identified for each patient, and those receiving retrievable IVCFs were further evaluated for retrieval rate and time to retrieval.ResultsOf the 762 filters placed, 133 were permanent filters. Of the 629 retrievable filters placed, 406 met the inclusion criteria and were eligible for retrieval. Results revealed patients with Medicare were less likely to have their filters retrieved (p = 0.031). Older age was also associated with a lower likelihood of retrieval (p < 0.001) as was living further from the medical center (p = 0.027). Patients who were white and had Medicare were more likely than similarly insured black patients to have their filters retrieved (p = 0.024).ConclusionsThe retrieval rate of IVCFs was most influenced by insurance status, distance from the medical center, and age. Race was statistically significant only when combined with insurance status. The results of this study suggest that these patient groups may need closer follow-up in order to obtain optimal IVCF retrieval rates

Cylindrical Hall Thrusters with Permanent Magnets

International Nuclear Information System (INIS)

Raitses, Yevgeny; Merino, Enrique; Fisch, Nathaniel J.

2010-01-01

The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction of both the total electric power consumption and the thruster mass. Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. The discharge and plasma plume measurements revealed that the CHT thrusters with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline. Differences in the magnetic field topology outside the thruster channel and in the vicinity of the channel exit are likely responsible for the differences in the plume characteristics measured for the CHTs with electromagnets and permanent magnets. It is shown that the presence of the reversing-direction or cusp-type magnetic field configuration inside the thruster channel without a strong axial magnetic field outside the thruster channel does not lead to the halo plasma plume from the CHT.

Macroscopic simulation of isotropic permanent magnets

International Nuclear Information System (INIS)

Bruckner, Florian; Abert, Claas; Vogler, Christoph; Heinrichs, Frank; Satz, Armin; Ausserlechner, Udo; Binder, Gernot; Koeck, Helmut; Suess, Dieter

2016-01-01

Accurate simulations of isotropic permanent magnets require to take the magnetization process into account and consider the anisotropic, nonlinear, and hysteretic material behaviour near the saturation configuration. An efficient method for the solution of the magnetostatic Maxwell equations including the description of isotropic permanent magnets is presented. The algorithm can easily be implemented on top of existing finite element methods and does not require a full characterization of the hysteresis of the magnetic material. Strayfield measurements of an isotropic permanent magnet and simulation results are in good agreement and highlight the importance of a proper description of the isotropic material. - Highlights: • Simulations of isotropic permanent magnets. • Accurate calculation of remanence magnetization and strayfield. • Comparison with strayfield measurements and anisotropic magnet simulations. • Efficient 3D FEM–BEM coupling for solution of Maxwell equations.

Reactor safety review of permanent changes

International Nuclear Information System (INIS)

Lam, K.F.

1997-01-01

Operational compliance engineers review all changes as part of a change control process. Each change, permanent or temporary, is required to undergo an intricate review process to ensure that the benefits associated with the change outweigh the risk. For permanent changes, it is necessary to ensure that the proposed design meets the nuclear safety requirements, conforms to the licensing requirements and complies with regulatory requirements. In addition, during installation of the permanent change and prior to in-service, a configuration management process is in place to align the change with operating and maintenance documents. (author)

Permanent multipole magnets with adjustable strength

International Nuclear Information System (INIS)

Halbach, K.

1983-01-01

Preceded by a short discussion of the motives for using permanent magnets in accelerators, a new type of permanent magnet for use in accelerators is presented. The basic design and most important properties of a quadrople will be described that uses both steel and permanent magnet material. The field gradient produced by this magnet can be adjusted without changing any other aspect of the field produced by this quadrupole. The generalization of this concept to produce other multipole fields, or combination of multipole fields, will also be presented

Nanocrystalline permanent magnets with enhanced properties

International Nuclear Information System (INIS)

Leonowicz, M.

2002-01-01

Parameters of permanent magnets result from the combination of intrinsic properties such as saturation magnetization, magnetic exchange, and magnetocrystalline energy, as well as microstructural parameters such as phase structure, grain size, and orientation. Reduction of grain size into nanocrystalline regime (∼ 50 nm) leads to the enhanced remanence which derives from ferromagnetic exchange coupling between highly refined grains. In this study the fundamental phenomena, quantities, and structure parameters, which define nanophase permanent magnets are presented and discussed. The theoretical considerations are confronted with experimental data for nanocrystalline Sm-Fe-N type permanent magnets. (author)

Permanent multipole magnets with adjustable strength

International Nuclear Information System (INIS)

Halbach, K.

1983-03-01

Preceded by a short discussion of the motives for using permanent magnets in accelerators, a new type of permanent magnet for use in accelerators is presented. The basic design and most important properties of a quadrupole will be described that uses both steel and permanent magnet material. The field gradient produced by this magnet can be adjusted without changing any other aspect of the field produced by this quadrupole. The generalization of this concept to produce other multipole fields, or combination of multipole fields, will also be presented

Introduction to permanent magnets

International Nuclear Information System (INIS)

Zijlstra, H.

1985-01-01

Some general considerations concerning the application of permanent magnets are developed. The relevant magnet properties are discussed, with particular reference to Nd-Fe-B alloy. The author comes to the following conclusions; the air gap field B should be high, for high electrical efficiency; the magnet should face the air gap, for efficient use of the magnet material; the magnet material should therefore have a high remanence; and the new Nd-Fe-B magnet fits in nicely, having (potentially) the highest remanence ever reported in permanent magnets, combined with sufficient coercivity to sustain it

Controlling flow conditions of test filters in iodine filters

International Nuclear Information System (INIS)

Holmberg, R.; Laine, J.

1979-03-01

Several different iodine filter and test filter designs and experience gained from their operation are presented. For the flow experiments, an iodine filter system equipped with flow regulating and measuring devices was built. In the experiments the influence of the packing method of the iodine sorption material and the influence of the flow regulating and measuring divices upon the flow conditions in the test filters was studied. On the basis of the experiments it has been shown that the flows through the test filters always can be adjusted to a correct value if there only is a high enough pressure difference available across the test filter ducting. As a result of the research, several different methods are presented with which the flows through the test filters in both operating and future iodine sorption system can easily be measured and adjusted to their correct values. (author)

The Rao-Blackwellized Particle Filter: A Filter Bank Implementation

Directory of Open Access Journals (Sweden)

Karlsson Rickard

2010-01-01

Full Text Available For computational efficiency, it is important to utilize model structure in particle filtering. One of the most important cases occurs when there exists a linear Gaussian substructure, which can be efficiently handled by Kalman filters. This is the standard formulation of the Rao-Blackwellized particle filter (RBPF. This contribution suggests an alternative formulation of this well-known result that facilitates reuse of standard filtering components and which is also suitable for object-oriented programming. Our RBPF formulation can be seen as a Kalman filter bank with stochastic branching and pruning.

Convergent Filter Bases

Directory of Open Access Journals (Sweden)

Coghetto Roland

2015-09-01

Full Text Available We are inspired by the work of Henri Cartan [16], Bourbaki [10] (TG. I Filtres and Claude Wagschal [34]. We define the base of filter, image filter, convergent filter bases, limit filter and the filter base of tails (fr: filtre des sections.

Permanent education

International Nuclear Information System (INIS)

Gardien, S.; Kirsch, R.

1998-01-01

The permanent education of the IPN-Lyon inscribes itself completely in the priorities of the tri-annual plan of education of CNRS. These priorities contribute to evolution of research, evaluation of the professions, integration during the professional carriers of the personnel and form the frame for new management practice implementation

Transient or permanent fisheye views

DEFF Research Database (Denmark)

Jakobsen, Mikkel Rønne; Hornbæk, Kasper

2012-01-01

Transient use of information visualization may support specific tasks without permanently changing the user interface. Transient visualizations provide immediate and transient use of information visualization close to and in the context of the user’s focus of attention. Little is known, however......, about the benefits and limitations of transient visualizations. We describe an experiment that compares the usability of a fisheye view that participants could call up temporarily, a permanent fisheye view, and a linear view: all interfaces gave access to source code in the editor of a widespread...... programming environment. Fourteen participants performed varied tasks involving navigation and understanding of source code. Participants used the three interfaces for between four and six hours in all. Time and accuracy measures were inconclusive, but subjective data showed a preference for the permanent...

Application of DFT Filter Banks and Cosine Modulated Filter Banks in Filtering

Science.gov (United States)

Lin, Yuan-Pei; Vaidyanathan, P. P.

1994-01-01

None given. This is a proposal for a paper to be presented at APCCAS '94 in Taipei, Taiwan. (From outline): This work is organized as follows: Sec. II is devoted to the construction of the new 2m channel under-decimated DFT filter bank. Implementation and complexity of this DFT filter bank are discussed therein. IN a similar manner, the new 2m channel cosine modulated filter bank is discussed in Sec. III. Design examples are given in Sec. IV.

Permanent molars: Delayed development and eruption

Directory of Open Access Journals (Sweden)

Arathi R

2006-05-01

Full Text Available Delayed development and eruption of all the permanent molars is a rare phenomenon, which can cause disturbance in the developing occlusion. The eruption of permanent first and second molars is very important for the coordination of facial growth and for providing sufficient occlusal support for undisturbed mastication. In the case described, the first permanent molars were delayed in their development and were seen erupting at the age of nine and a half years. Severe disparity between the left and the right side of the dentition with respect to the rate of development of molars were also present.

Output Feedback Adaptive Dynamic Surface Control of Permanent Magnet Synchronous Motor with Uncertain Time Delays via RBFNN

Directory of Open Access Journals (Sweden)

Shaohua Luo

2014-01-01

Full Text Available This paper focuses on an adaptive dynamic surface control based on the Radial Basis Function Neural Network for a fourth-order permanent magnet synchronous motor system wherein the unknown parameters, disturbances, chaos, and uncertain time delays are presented. Neural Network systems are used to approximate the nonlinearities and an adaptive law is employed to estimate accurate parameters. Then, a simple and effective controller has been obtained by introducing dynamic surface control technique on the basis of first-order filters. Asymptotically tracking stability in the sense of uniformly ultimate boundedness is achieved in a short time. Finally, the performance of the proposed control has been illustrated through simulation results.

Superconducting permanent magnets

International Nuclear Information System (INIS)

Wipf, S.L.; Laquer, H.L.

1989-01-01

The concept of superconducting permanent magnets with fields trapped in shells or cylinders of Type II superconductors is an old one. Unfortunately, the low values of 0.5 to 1T for the first flux jump field, which is independent of the actual current density, have frustrated its implementation with classical Type II superconductors. The fact that the flux jump fields for high temperature superconductors should be an order of magnitude larger at liquid nitrogen temperatures allows us to reconsider these options. Analysis of the hysteresis patterns, based on the critical state model, shows that, if the dimensions are chosen so that the sample is penetrated at a field B/sub p/, which is equal to or just less than the first flux jump field, B/sub fj/, a temporarily applied field of 2B/sub fj/ will trap 0.5 B/sub fj/. Thus for a 90 K superconductor with a B/sub fj/ of 6T, a permanent field of 3 T should be trapped, with an energy product of 1.8 MJ/m/sup 3/ (225 MG . Oe). This is five times as large as for the best permanent magnet materials. The authors discuss means to verify the analysis and the limitations imposed by the low critical current densities in presently available high temperature superconductors

A Study of Parallel Operation of an active Filter and passive Filters

DEFF Research Database (Denmark)

Chen, Zhe; Blaabjerg, Frede; Pedersen, John Kim

2002-01-01

This paper reports investigations of the parallel operations of a current controlled active filter and passive filters in a system with current harmonic sources. The task of reactive power and harmonic compensation is shared by the active filter and passive filters. The passive filters are used...... arrangements of the active and passive filters can operate relatively independently, also the compensation flexibility of the active filter can be fully exploited, such as one active filter for several harmonic sources.The simulation studies on various systems have been performed to evaluate the effectiveness...... of the systems. The results show that the power factor is corrected by the passive filters, harmonics are minimized by both active and passive filters and overloading of the filter system can be avoided....

Passive Power Filters

CERN Document Server

Künzi, R.

2015-06-15

Power converters require passive low-pass filters which are capable of reducing voltage ripples effectively. In contrast to signal filters, the components of power filters must carry large currents or withstand large voltages, respectively. In this paper, three different suitable filter struc tures for d.c./d.c. power converters with inductive load are introduced. The formulas needed to calculate the filter components are derived step by step and practical examples are given. The behaviour of the three discussed filters is compared by means of the examples. P ractical aspects for the realization of power filters are also discussed.

Particle Kalman Filtering: A Nonlinear Bayesian Framework for Ensemble Kalman Filters*

KAUST Repository

Hoteit, Ibrahim

2012-02-01

This paper investigates an approximation scheme of the optimal nonlinear Bayesian filter based on the Gaussian mixture representation of the state probability distribution function. The resulting filter is similar to the particle filter, but is different from it in that the standard weight-type correction in the particle filter is complemented by the Kalman-type correction with the associated covariance matrices in the Gaussian mixture. The authors show that this filter is an algorithm in between the Kalman filter and the particle filter, and therefore is referred to as the particle Kalman filter (PKF). In the PKF, the solution of a nonlinear filtering problem is expressed as the weighted average of an “ensemble of Kalman filters” operating in parallel. Running an ensemble of Kalman filters is, however, computationally prohibitive for realistic atmospheric and oceanic data assimilation problems. For this reason, the authors consider the construction of the PKF through an “ensemble” of ensemble Kalman filters (EnKFs) instead, and call the implementation the particle EnKF (PEnKF). It is shown that different types of the EnKFs can be considered as special cases of the PEnKF. Similar to the situation in the particle filter, the authors also introduce a resampling step to the PEnKF in order to reduce the risk of weights collapse and improve the performance of the filter. Numerical experiments with the strongly nonlinear Lorenz-96 model are presented and discussed.

Rectifier Filters

Directory of Open Access Journals (Sweden)

Y. A. Bladyko

2010-01-01

Full Text Available The paper contains definition of a smoothing factor which is suitable for any rectifier filter. The formulae of complex smoothing factors have been developed for simple and complex passive filters. The paper shows conditions for application of calculation formulae and filters. 

Lawful Permanent Residents Fiscal Year 2011 Country

Data.gov (United States)

Department of Homeland Security — Lawful permanet residents (LPRs) are foreign nationals who have been gratned the right to reside permanently in the United States. LPRs are also known as 'permanent...

Multidetector-row computed tomography management of acute pulmonary embolism

International Nuclear Information System (INIS)

Yasui, Takahiro; Tanabe, Nobuhiro; Terada, Jiro

2007-01-01

The purpose of this study was to evaluate the usefulness and safety of multidetector-row computed tomography (MDCT) pulmonary angiography and indirect venography management of acute pulmonary embolism (PE), including indication for inferior vena cava (IVC) filter. Seventy-one consecutive patients who were clinically suspected of PE and underwent 16-slice MDCT pulmonary angiography and indirect venography were enrolled. Management included indication of IVC filter for patients with extensive deep venous thrombosis (DVT) in submassive or massive PE. A right ventricular to left ventricular short-axis diameter by MDCT >1.0 was judged as submassive PE. All patients were followed for 1 year. MDCT identified 50 patients with venous thromboembolism and 47 patients had acute PE: 4 were judged as massive, 14 as submassive, and 29 as non-massive by MDCT; 3 patients had DVT alone and 7 patients had caval or iliac DVT. Only 1 patient with massive PE and DVT near the right atrium died of recurrence. No other patients died of PE. Management based on MDCT pulmonary angiography combined with indirect venography is considered to be safe and reliable in patients with suspected acute PE. (author)

Permanent magnet design for high-speed superconducting bearings

Science.gov (United States)

Hull, John R.; Uherka, Kenneth L.; Abdoud, Robert G.

1996-01-01

A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing.

Retina-Inspired Filter.

Science.gov (United States)

Doutsi, Effrosyni; Fillatre, Lionel; Antonini, Marc; Gaulmin, Julien

2018-07-01

This paper introduces a novel filter, which is inspired by the human retina. The human retina consists of three different layers: the Outer Plexiform Layer (OPL), the inner plexiform layer, and the ganglionic layer. Our inspiration is the linear transform which takes place in the OPL and has been mathematically described by the neuroscientific model "virtual retina." This model is the cornerstone to derive the non-separable spatio-temporal OPL retina-inspired filter, briefly renamed retina-inspired filter, studied in this paper. This filter is connected to the dynamic behavior of the retina, which enables the retina to increase the sharpness of the visual stimulus during filtering before its transmission to the brain. We establish that this retina-inspired transform forms a group of spatio-temporal Weighted Difference of Gaussian (WDoG) filters when it is applied to a still image visible for a given time. We analyze the spatial frequency bandwidth of the retina-inspired filter with respect to time. It is shown that the WDoG spectrum varies from a lowpass filter to a bandpass filter. Therefore, while time increases, the retina-inspired filter enables to extract different kinds of information from the input image. Finally, we discuss the benefits of using the retina-inspired filter in image processing applications such as edge detection and compression.

Permanent magnet design for high-speed superconducting bearings

International Nuclear Information System (INIS)

Hull, J.R.; Uherka, K.L.; Abdoud, R.G.

1996-01-01

A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure is disclosed. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing. 9 figs

Braile vena cava filter and greenfield filter in terms of centralization.

Science.gov (United States)

de Godoy, José Maria Pereira; Menezes da Silva, Adinaldo A; Reis, Luis Fernando; Miquelin, Daniel; Torati, José Luis Simon

2013-01-01

The aim of this study was to evaluate complications experienced during implantation of the Braile Vena Cava filter (VCF) and the efficacy of the centralization mechanism of the filter. This retrospective cohort study evaluated all Braile Biomédica VCFs implanted from 2004 to 2009 in Hospital de Base Medicine School in São José do Rio Preto, Brazil. Of particular concern was the filter's symmetry during implantation and complications experienced during the procedure. All the angiographic examinations performed during the implantation of the filters were analyzed in respect to the following parameters: migration of the filter, non-opening or difficulties in the implantation and centralization of the filter. A total of 112 Braile CVFs were implanted and there were no reports of filter opening difficulties or in respect to migration. Asymmetry was observed in 1/112 (0.9%) cases. A statistically significant difference was seen on comparing historical data on decentralization of the Greenfield filter with the data of this study. The Braile Biomédico filter is an evolution of the Greenfield filter providing improved embolus capture and better implantation symmetry.

Safety effects of permanent running lights for bicycles

DEFF Research Database (Denmark)

Madsen, Jens Chr. Overgaard; Andersen, T.; Lahrmann, Harry

2013-01-01

, including all recorded bicycle accidents with personal injury to the participating cyclist, is 19% lower for cyclists with permanent running lights mounted; indicating that the permanent bicycle running light significantly improves traffic safety for cyclists. The study shows that use of permanent bicycle......Making the use of daytime running lights mandatory for motor vehicles is generally documented to have had a positive impact upon traffic safety. Improving traffic safety for bicyclists is a focal point in the road traffic safety work in Denmark. In 2004 and 2005 a controlled experiment including...... 3845 cyclists was carried out in Odense, Denmark in order to examine, if permanent running lights mounted to bicycles would improve traffic safety for cyclists. The permanent running lights were mounted to 1845 bicycles and the accident rate was recorded through 12 months for this treatment group...

A New Adaptive Self-Tuning Fourier Coefficients Algorithm for Periodic Torque Ripple Minimization in Permanent Magnet Synchronous Motors (PMSM

Directory of Open Access Journals (Sweden)

Gilberto Herrera-Ruíz

2013-03-01

Full Text Available A New Adaptive Self-Tuning Fourier Coefficients Algorithm for Periodic Torque Ripple Minimization in Permanent Magnet Synchronous Motors (PMSM Torque ripple occurs in Permanent Magnet Synchronous Motors (PMSMs due to the non-sinusoidal flux density distribution around the air-gap and variable magnetic reluctance of the air-gap due to the stator slots distribution. These torque ripples change periodically with rotor position and are apparent as speed variations, which degrade the PMSM drive performance, particularly at low speeds, because of low inertial filtering. In this paper, a new self-tuning algorithm is developed for determining the Fourier Series Controller coefficients with the aim of reducing the torque ripple in a PMSM, thus allowing for a smoother operation. This algorithm adjusts the controller parameters based on the component’s harmonic distortion in time domain of the compensation signal. Experimental evaluation is performed on a DSP-controlled PMSM evaluation platform. Test results obtained validate the effectiveness of the proposed self-tuning algorithm, with the Fourier series expansion scheme, in reducing the torque ripple.

A new adaptive self-tuning Fourier coefficients algorithm for periodic torque ripple minimization in permanent magnet synchronous motors (PMSM).

Science.gov (United States)

Gómez-Espinosa, Alfonso; Hernández-Guzmán, Víctor M; Bandala-Sánchez, Manuel; Jiménez-Hernández, Hugo; Rivas-Araiza, Edgar A; Rodríguez-Reséndiz, Juvenal; Herrera-Ruíz, Gilberto

2013-03-19

A New Adaptive Self-Tuning Fourier Coefficients Algorithm for Periodic Torque Ripple Minimization in Permanent Magnet Synchronous Motors (PMSM) Torque ripple occurs in Permanent Magnet Synchronous Motors (PMSMs) due to the non-sinusoidal flux density distribution around the air-gap and variable magnetic reluctance of the air-gap due to the stator slots distribution. These torque ripples change periodically with rotor position and are apparent as speed variations, which degrade the PMSM drive performance, particularly at low speeds, because of low inertial filtering. In this paper, a new self-tuning algorithm is developed for determining the Fourier Series Controller coefficients with the aim of reducing the torque ripple in a PMSM, thus allowing for a smoother operation. This algorithm adjusts the controller parameters based on the component's harmonic distortion in time domain of the compensation signal. Experimental evaluation is performed on a DSP-controlled PMSM evaluation platform. Test results obtained validate the effectiveness of the proposed self-tuning algorithm, with the Fourier series expansion scheme, in reducing the torque ripple.

Balanced microwave filters

CERN Document Server

Hong, Jiasheng; Medina, Francisco; Martiacuten, Ferran

2018-01-01

This book presents and discusses strategies for the design and implementation of common-mode suppressed balanced microwave filters, including, narrowband, wideband, and ultra-wideband filters This book examines differential-mode, or balanced, microwave filters by discussing several implementations of practical realizations of these passive components. Topics covered include selective mode suppression, designs based on distributed and semi-lumped approaches, multilayer technologies, defect ground structures, coupled resonators, metamaterials, interference techniques, and substrate integrated waveguides, among others. Divided into five parts, Balanced Microwave Filters begins with an introduction that presents the fundamentals of balanced lines, circuits, and networks. Part 2 covers balanced transmission lines with common-mode noise suppression, including several types of common-mode filters and the application of such filters to enhance common-mode suppression in balanced bandpass filters. Next, Part 3 exa...

Workplace bullying a risk for permanent employees.

Science.gov (United States)

Keuskamp, Dominic; Ziersch, Anna M; Baum, Fran E; Lamontagne, Anthony D

2012-04-01

We tested the hypothesis that the risk of experiencing workplace bullying was greater for those employed on casual contracts compared to permanent or ongoing employees. A cross-sectional population-based telephone survey was conducted in South Australia in 2009. Employment arrangements were classified by self-report into four categories: permanent, casual, fixed-term and self-employed. Self-report of workplace bullying was modelled using multiple logistic regression in relation to employment arrangement, controlling for sex, age, working hours, years in job, occupational skill level, marital status and a proxy for socioeconomic status. Workplace bullying was reported by 174 respondents (15.2%). Risk of workplace bullying was higher for being in a professional occupation, having a university education and being separated, divorced or widowed, but did not vary significantly by sex, age or job tenure. In adjusted multivariate logistic regression models, casual workers were significantly less likely than workers on permanent or fixed-term contracts to report bullying. Those separated, divorced or widowed had higher odds of reporting bullying than married, de facto or never-married workers. Contrary to expectation, workplace bullying was more often reported by permanent than casual employees. It may represent an exposure pathway not previously linked with the more idealised permanent employment arrangement. A finer understanding of psycho-social hazards across all employment arrangements is needed, with equal attention to the hazards associated with permanent as well as casual employment. © 2012 The Authors. ANZJPH © 2012 Public Health Association of Australia.

Filter replacement lifetime prediction

Science.gov (United States)

Hamann, Hendrik F.; Klein, Levente I.; Manzer, Dennis G.; Marianno, Fernando J.

2017-10-25

Methods and systems for predicting a filter lifetime include building a filter effectiveness history based on contaminant sensor information associated with a filter; determining a rate of filter consumption with a processor based on the filter effectiveness history; and determining a remaining filter lifetime based on the determined rate of filter consumption. Methods and systems for increasing filter economy include measuring contaminants in an internal and an external environment; determining a cost of a corrosion rate increase if unfiltered external air intake is increased for cooling; determining a cost of increased air pressure to filter external air; and if the cost of filtering external air exceeds the cost of the corrosion rate increase, increasing an intake of unfiltered external air.

Anti-clogging filter system

Science.gov (United States)

Brown, Erik P.

2015-05-19

An anti-clogging filter system for filtering a fluid containing large particles and small particles includes an enclosure with at least one individual elongated tubular filter element in the enclosure. The individual elongated tubular filter element has an internal passage, a closed end, an open end, and a filtering material in or on the individual elongated tubular filter element. The fluid travels through the open end of the elongated tubular element and through the internal passage and through the filtering material. An anti-clogging element is positioned on or adjacent the individual elongated tubular filter element and provides a fluid curtain that preferentially directs the larger particulates to one area of the filter material allowing the remainder of the filter material to remain more efficient.

Selection vector filter framework

Science.gov (United States)

Lukac, Rastislav; Plataniotis, Konstantinos N.; Smolka, Bogdan; Venetsanopoulos, Anastasios N.

2003-10-01

We provide a unified framework of nonlinear vector techniques outputting the lowest ranked vector. The proposed framework constitutes a generalized filter class for multichannel signal processing. A new class of nonlinear selection filters are based on the robust order-statistic theory and the minimization of the weighted distance function to other input samples. The proposed method can be designed to perform a variety of filtering operations including previously developed filtering techniques such as vector median, basic vector directional filter, directional distance filter, weighted vector median filters and weighted directional filters. A wide range of filtering operations is guaranteed by the filter structure with two independent weight vectors for angular and distance domains of the vector space. In order to adapt the filter parameters to varying signal and noise statistics, we provide also the generalized optimization algorithms taking the advantage of the weighted median filters and the relationship between standard median filter and vector median filter. Thus, we can deal with both statistical and deterministic aspects of the filter design process. It will be shown that the proposed method holds the required properties such as the capability of modelling the underlying system in the application at hand, the robustness with respect to errors in the model of underlying system, the availability of the training procedure and finally, the simplicity of filter representation, analysis, design and implementation. Simulation studies also indicate that the new filters are computationally attractive and have excellent performance in environments corrupted by bit errors and impulsive noise.

Nonuniform radiation damage in permanent magnet quadrupoles.

Science.gov (United States)

Danly, C R; Merrill, F E; Barlow, D; Mariam, F G

2014-08-01

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL's pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Nonuniform radiation damage in permanent magnet quadrupoles

International Nuclear Information System (INIS)

Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G.

2014-01-01

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components

Nonuniform radiation damage in permanent magnet quadrupoles

Energy Technology Data Exchange (ETDEWEB)

Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

2014-08-15

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Opportunities and Difficulties in the Implementation of Projects Financed Through the Interreg IVC Program in Romania. Case Study: The Project "Public Policies and Social Enterprises"

Directory of Open Access Journals (Sweden)

Daniela PÎRVU

2011-02-01

Full Text Available In Europe today, economic success is often dependent on a region’s capacity to develop networks with other regions. Cooperation and experience sharing between regions can be a key trigger in stimulating a dynamic, forwardlooking regional development process. The EU has an important role to play in brokering and supporting partnerships between regions within the Union. Thousands of projects developed over many years under the INTERREG initiative have demonstrated the benefits for regions of working in partnership, sharing ideas and charting new and innovative ways of harnessing European investment. The analysis of the implementation of the projects financed through the INTERREG IVC Program proves that the development of the interregional European cooperation is constrained by the practical difficulties generated by various administrative systems and by the differences among competences on the levels of the public administration of the European Union member states.

Globally Optimal Segmentation of Permanent-Magnet Systems

DEFF Research Database (Denmark)

Insinga, Andrea Roberto; Bjørk, Rasmus; Smith, Anders

2016-01-01

Permanent-magnet systems are widely used for generation of magnetic fields with specific properties. The reciprocity theorem, an energy-equivalence principle in magnetostatics, can be employed to calculate the optimal remanent flux density of the permanent-magnet system, given any objective...... remains unsolved. We show that the problem of optimal segmentation of a two-dimensional permanent-magnet assembly with respect to a linear objective functional can be reduced to the problem of piecewise linear approximation of a plane curve by perimeter maximization. Once the problem has been cast...

Changing ventilation filters

International Nuclear Information System (INIS)

Hackney, S.

1980-01-01

A filter changing unit has a door which interlocks with the door of a filter chamber so as to prevent contamination of the outer surfaces of the doors by radioactive material collected on the filter element and a movable support which enables a filter chamber thereonto to be stored within the unit in such a way that the doors of the unit and the filter chamber can be replaced. The door pivots and interlocks with another door by means of a bolt, a seal around the periphery lip of the first door engages the periphery of the second door to seal the gap. A support pivots into a lower filter element storage position. Inspection windows and glove ports are provided. The unit is releasably connected to the filter chamber by bolts engaging in a flange provided around an opening. (author)

Object permanence in adults : a cross-cultural perspective

OpenAIRE

Subbotski, Eugene; Trommsdorff, Gisela

1992-01-01

Soviet and German adult subjects observed the phenomenon of object non-permanence (destruction, reconstruction, or transformation of a physical object). Both samples attributed an equal degree of probability to real existence of object non-permanence. However, Soviet subjects attributed a significantly higher probability to the existence of "religion-independent" non-permanent mysterious phenomena, (e.g., "unidentified flying objects", "abominable snowman", "Loch Ness monster") while attribut...

Generation of magnetic fields for accelerators with permanent magnets

International Nuclear Information System (INIS)

Meinander, T.

1994-01-01

Commercially available permanent magnet materials and their properties are reviewed. Advantages and disadvantages of using permanent magnets as compared to electromagnets for the generation of specific magnetic fields are discussed. Basic permanent magnet configurations in multipole magnets and insertion devices are presented. (orig.)

Device for automatic filter changing. Einrichtung zum selbsttaetigen Wechseln eines Filters

Energy Technology Data Exchange (ETDEWEB)

Matschoss, V; Naschwitz, A; Wild, H

1984-01-05

A filter is moved from a store to an aerosol pipe by a lifting device and is clamped there. At the end of the operating period, the lifting device moves a new filter to a parking place. Control is from limit switches of the lifting, clamping and thrust devices and the position control of the store is by the limit switches. The filter changing device is enclosed in a gastight case, prevents blockage of a filter and makes it possible to set a certain operating period, to change the filter without interrupting the aerosol flow and to measure each filter in the sequence of operation outside the aerosol flow.

Gunther Tulip Inferior Vena Cava Filter Placement During Treatment for Deep Venous Thrombosis of the Lower Extremity

International Nuclear Information System (INIS)

Yamagami, Takuji; Kato, Takeharu; Iida, Shigeharu; Hirota, Tatsuya; Nishimura, Tsunehiko

2005-01-01

Purpose. To evaluate the efficacy and safety of Gunther tulip retrievable vena cava filter (GTF) implantation to prevent pulmonary embolism during intravenously administered thrombolytic and anticoagulation therapy and interventional radiological therapy for occlusive or nonocclusive deep venous thrombosis (DVT) of the lower extremity. Methods. We evaluated placement of 55 GTFs in 42 patients with lower extremity DVT who had undergone various treatments including those utilizing techniques of interventional radiology. Results. Worsening of pulmonary embolism in patients with existing pulmonary embolism or in those without pulmonary embolism at the time of GTF insertion was avoided in all patients. All attempts at implantation of the GTF were safely accomplished. Perforation and migration experienced by one patient was the only complication. Mean period of treatment for DVT under protection from pulmonary embolism by the GTF was 12.7 ± 8.3 days (mean ± SD, range 4-37 days). We attempted retrieval of GTFs in 18 patients in whom the venous thrombus had disappeared after therapy, and retrieval in one of these 18 cases failed. GTFs were left in the vena cava in 24 patients for permanent use when the DVT was refractory to treatment. Conclusion. The ability of the GTF to protect against pulmonary embolism during treatment of DVT was demonstrated. Safety in both placement and retrieval was clarified. Because replacement with a permanent filter was not required, use of the GTF was convenient when further protection from complicated pulmonary embolism was necessary

Sensory pollution from bag-type fiberglass ventilation filters: Conventional filter compared with filters containing various amounts of activated carbon

DEFF Research Database (Denmark)

Bekö, Gabriel; Fadeyi, M.O.; Clausen, Geo

2009-01-01

filter and three modifications of a bag-type fiberglass combination filter: the "Heavy" corresponded to a commercially available filter containing 400 g of carbon per square meter of filter area, the "Medium" contained half as much carbon (200 g/m(2)), and the "Light" contained a quarter as much carbon...

A Differential Geometric Approach to Nonlinear Filtering: The Projection Filter

NARCIS (Netherlands)

Brigo, D.; Hanzon, B.; LeGland, F.

1998-01-01

This paper presents a new and systematic method of approximating exact nonlinear filters with finite dimensional filters, using the differential geometric approach to statistics. The projection filter is defined rigorously in the case of exponential families. A convenient exponential family is

Dovetail spoke internal permanent magnet machine

Science.gov (United States)

Alexander, James Pellegrino [Ballston Lake, NY; EL-Refaie, Ayman Mohamed Fawzi [Niskayuna, NY; Lokhandwalla, Murtuza [Clifton Park, NY; Shah, Manoj Ramprasad [Latham, NY; VanDam, Jeremy Daniel [West Coxsackie, NY

2011-08-23

An internal permanent magnet (IPM) machine is provided. The IPM machine includes a stator assembly and a stator core. The stator core also includes multiple stator teeth. The stator assembly is further configured with stator windings to generate a stator magnetic field when excited with alternating currents and extends along a longitudinal axis with an inner surface defining a cavity. The IPM machine also includes a rotor assembly and a rotor core. The rotor core is disposed inside the cavity and configured to rotate about the longitudinal axis. The rotor assembly further includes a shaft. The shaft further includes multiple protrusions alternately arranged relative to multiple bottom structures provided on the shaft. The rotor assembly also includes multiple stacks of laminations disposed on the protrusions and dovetailed circumferentially around the shaft. The rotor assembly further includes multiple pair of permanent magnets for generating a magnetic field, which magnetic field interacts with the stator magnetic field to produce a torque. The multiple pair of permanent magnets are disposed between the stacks. The rotor assembly also includes multiple middle wedges mounted between each pair of the multiple permanent magnets.

Filter and Filter Bank Design for Image Texture Recognition

Energy Technology Data Exchange (ETDEWEB)

Randen, Trygve

1997-12-31

The relevance of this thesis to energy and environment lies in its application to remote sensing such as for instance sea floor mapping and seismic pattern recognition. The focus is on the design of two-dimensional filters for feature extraction, segmentation, and classification of digital images with textural content. The features are extracted by filtering with a linear filter and estimating the local energy in the filter response. The thesis gives a review covering broadly most previous approaches to texture feature extraction and continues with proposals of some new techniques. 143 refs., 59 figs., 7 tabs.

HEPA Filter Vulnerability Assessment

International Nuclear Information System (INIS)

GUSTAVSON, R.D.

2000-01-01

This assessment of High Efficiency Particulate Air (HEPA) filter vulnerability was requested by the USDOE Office of River Protection (ORP) to satisfy a DOE-HQ directive to evaluate the effect of filter degradation on the facility authorization basis assumptions. Within the scope of this assessment are ventilation system HEPA filters that are classified as Safety-Class (SC) or Safety-Significant (SS) components that perform an accident mitigation function. The objective of the assessment is to verify whether HEPA filters that perform a safety function during an accident are likely to perform as intended to limit release of hazardous or radioactive materials, considering factors that could degrade the filters. Filter degradation factors considered include aging, wetting of filters, exposure to high temperature, exposure to corrosive or reactive chemicals, and exposure to radiation. Screening and evaluation criteria were developed by a site-wide group of HVAC engineers and HEPA filter experts from published empirical data. For River Protection Project (RPP) filters, the only degradation factor that exceeded the screening threshold was for filter aging. Subsequent evaluation of the effect of filter aging on the filter strength was conducted, and the results were compared with required performance to meet the conditions assumed in the RPP Authorization Basis (AB). It was found that the reduction in filter strength due to aging does not affect the filter performance requirements as specified in the AB. A portion of the HEPA filter vulnerability assessment is being conducted by the ORP and is not part of the scope of this study. The ORP is conducting an assessment of the existing policies and programs relating to maintenance, testing, and change-out of HEPA filters used for SC/SS service. This document presents the results of a HEPA filter vulnerability assessment conducted for the River protection project as requested by the DOE Office of River Protection

Permanent Magnet Eddy Current Loss Analysis of a Novel Motor Integrated Permanent Magnet Gear

DEFF Research Database (Denmark)

Zhang, Yuqiu; Lu, Kaiyuan; Ye, Yunyue

2012-01-01

In this paper, a new motor integrated permanent magnet gear (MIPMG) is discussed. The focus is on eddy current loss analysis associated to permanent magnets (PMs). A convenient model of MIPMG is provided based on 2-D field-motion coupled time-stepping finite element method for transient eddy...... current analysis. The model takes the eddy current effect of PMs into account in determination of the magnetic field in the air-gap and in the magnet regions. The eddy current losses generated in the magnets are properly interpreted. Design improvements for reducing the eddy current losses are suggested...

Potential for HEPA filter damage from water spray systems in filter plenums

Energy Technology Data Exchange (ETDEWEB)

Bergman, W. [Lawrence Livermore National Lab., CA (United States); Fretthold, J.K. [Rocky Flats Safe Sites of Colorado, Golden, CO (United States); Slawski, J.W. [Department of Energy, Germantown, MD (United States)

1997-08-01

The water spray systems in high efficiency particulate air (HEPA) filter plenums that are used in nearly all Department of Energy (DOE) facilities for protection against fire was designed under the assumption that the HEPA filters would not be damaged by the water sprays. The most likely scenario for filter damage involves filter plugging by the water spray, followed by the fan blowing out the filter medium. A number of controlled laboratory tests that were previously conducted in the late 1980s are reviewed in this paper to provide a technical basis for the potential HEPA filter damage by the water spray system in HEPA filter plenums. In addition to the laboratory tests, the scenario for BEPA filter damage during fires has also occurred in the field. A fire in a four-stage, BEPA filter plenum at Rocky Flats in 1980 caused the first three stages of BEPA filters to blow out of their housing and the fourth stage to severely bow. Details of this recently declassified fire are presented in this paper. Although these previous findings suggest serious potential problems exist with the current water spray system in filter plenums, additional studies are required to confirm unequivocally that DOE`s critical facilities are at risk. 22 refs., 15 figs.

Permanent isolation surface barrier development plan

International Nuclear Information System (INIS)

Wing, N.R.

1994-01-01

The exhumation and treatment of wastes may not always be the preferred alternative in the remediation of a waste site. In-place disposal alternatives, under certain circumstances, may be the most desirable alternatives to use in the protection of human health and the environment. The implementation of an in-place disposal alternative will likely require some type of protective covering that will provide long-term isolation of the wastes from the accessible environment. Even if the wastes are exhumed and treated, a long-term barrier may still be needed to adequately dispose of the treated wastes or any remaining waste residuals. Currently, no open-quotes provenclose quotes long-term barrier is available. The Hanford Site Permanent Isolation Surface Barrier Development Program (BDP) was organized to develop the technology needed to provide a long-term surface barrier capability for the Hanford Site. The permanent isolation barrier technology also could be used at other sites. Permanent isolation barriers use engineered layers of natural materials to create an integrated structure with redundant protective features. Drawings of conceptual permanent isolation surface barriers are shown. The natural construction materials (e.g., fine soil, sand, gravel, riprap, asphalt) have been selected to optimize barrier performance and longevity. The objective of current designs is to use natural materials to develop a maintenance-free permanent isolation surface barrier that isolates wastes for a minimum of 1,000 years by limiting water drainage to near-zero amounts; reducing the likelihood of plant, animal, and human intrusion; controlling the exhalation of noxious gases; and minimizing erosion-related problems

Permanent isolation surface barrier development plan

Energy Technology Data Exchange (ETDEWEB)

Wing, N.R.

1994-01-01

The exhumation and treatment of wastes may not always be the preferred alternative in the remediation of a waste site. In-place disposal alternatives, under certain circumstances, may be the most desirable alternatives to use in the protection of human health and the environment. The implementation of an in-place disposal alternative will likely require some type of protective covering that will provide long-term isolation of the wastes from the accessible environment. Even if the wastes are exhumed and treated, a long-term barrier may still be needed to adequately dispose of the treated wastes or any remaining waste residuals. Currently, no {open_quotes}proven{close_quotes} long-term barrier is available. The Hanford Site Permanent Isolation Surface Barrier Development Program (BDP) was organized to develop the technology needed to provide a long-term surface barrier capability for the Hanford Site. The permanent isolation barrier technology also could be used at other sites. Permanent isolation barriers use engineered layers of natural materials to create an integrated structure with redundant protective features. Drawings of conceptual permanent isolation surface barriers are shown. The natural construction materials (e.g., fine soil, sand, gravel, riprap, asphalt) have been selected to optimize barrier performance and longevity. The objective of current designs is to use natural materials to develop a maintenance-free permanent isolation surface barrier that isolates wastes for a minimum of 1,000 years by limiting water drainage to near-zero amounts; reducing the likelihood of plant, animal, and human intrusion; controlling the exhalation of noxious gases; and minimizing erosion-related problems.

Adjustable permanent magnet assembly for NMR and MRI

Science.gov (United States)

Pines, Alexander; Paulsen, Jeffrey; Bouchard, Louis S; Blumich, Bernhard

2013-10-29

System and methods for designing and using single-sided magnet assemblies for magnetic resonance imaging (MRI) are disclosed. The single-sided magnet assemblies can include an array of permanent magnets disposed at selected positions. At least one of the permanent magnets can be configured to rotate about an axis of rotation in the range of at least +/-10 degrees and can include a magnetization having a vector component perpendicular to the axis of rotation. The single-sided magnet assemblies can further include a magnet frame that is configured to hold the permanent magnets in place while allowing the at least one of the permanent magnets to rotate about the axis of rotation.

Method and apparatus for assembling permanent magnet rotors

Science.gov (United States)

Hsu, J.S.; Adams, D.J.

1999-06-22

A permanent magnet assembly for assembly in large permanent magnet motors and generators includes a two-piece carrier that can be slid into a slot in the rotor and then secured in place using a set screw. The invention also provides an auxiliary carrier device with guide rails that line up with the teeth of the rotor, so that a permanent magnet assembly can be pushed first into a slot, and then down the slot to its proper location. An auxiliary tool is provided to move the permanent magnet assembly into position in the slot before it is secured in place. Methods of assembling and disassembling the magnet assemblies in the rotor are also disclosed. 2 figs.

Corporate Policies with Permanent and Transitory Shocks

NARCIS (Netherlands)

J-P. Decamps (Jean-Paul); S. Gryglewicz (Sebastian); E. Morellec (Erwan); S. Villeneuve (Stephane)

2016-01-01

textabstractWe model the financing, cash holdings, and hedging policies of a firm facing financing frictions and subject to permanent and transitory cash flow shocks. We show that permanent and transitory shocks generate distinct, sometimes opposite, effects on corporate policies and use the model

Connecting Temporary and Permanent Organizing

DEFF Research Database (Denmark)

Stjerne, Iben Sandal; Velikova, Silviya Svejenova

2016-01-01

This paper investigates the relationship between a permanent organization and a series of temporary organizations. It draws on an in-depth study of the process through which a Danish film production company, seeking to balance innovation and persistence in a troubled industry, struggles to realize...... a novel children’s film and its sequels. The study reveals tensions at different levels as well as boundary work and boundary roles that address them, bringing in shadows of past and future projects. The study extends the understanding of the dialectic between temporary and permanent organizing...

Effect of B-mercaptoethanol on the viability of IVM/IVF/IVC bovine embryos during long-distance transportation in plastic straws.

Science.gov (United States)

Takahashi, H; Kuwayama, M; Hamano, S; Takahashi, M; Okano, A; Kadokawa, H; Kariya, T; Nagai, T

1996-10-15

Experiments were conducted to assess the effect of beta-mercaptoethanol (beta-ME) on the quality and viability of bovine blastocysts derived from in-vitro culture (IVC) of in-vitro matured and fertilized (TVM-IVF) oocytes during their transport between 2 distant places. Follicular oocytes were collected from ovaries obtained at a slaughterhouse and were cultured for 20 to 21 h in modified TCM-199. The IVM oocytes were fertilized in vitro with frozen-thawed spermatozoa. Fertilized oocytes were cultured for 7 d, and embryos that developed to the blastocyst stage were used for the experiments. The blastocysts, packed in straws with transportation medium that consisted of modified TCM-199 with HEPES equilibrated in air and supplemented with 20 % calf serum and 0, 10, 50, 100 or 150 microM beta-ME, were transported at 37 degrees C from Tokyo to Sapporo by air (18.3 h). The quality of blastocysts was assessed and ranked as excellent (A), good (B), fair (C) or poor (D) after transportation. The percentages of blastocysts ranked as A or B were significantly higher (P plastic straws for several hours without control of CO2 and that the concentration of beta-ME used in this experiment is not detrimental to the blastocysts.

Neutron Beam Filters

International Nuclear Information System (INIS)

Adib, M.

2011-01-01

The purpose of filters is to transmit neutrons with selected energy, while remove unwanted ones from the incident neutron beam. This reduces the background, and the number of spurious. The types of commonly used now-a-day neutron filters and their properties are discussed in the present work. There are three major types of neutron filters. The first type is filter of selective thermal neutron. It transmits the main reflected neutrons from a crystal monochromate, while reject the higher order contaminations accompanying the main one. Beams coming from the moderator always contain unwanted radiation like fast neutrons and gamma-rays which contribute to experimental background and to the biological hazard potential. Such filter type is called filter of whole thermal neutron spectrum. The third filter type is it transmits neutrons with energies in the resonance energy range (En . 1 KeV). The main idea of such neutron filter technique is the use of large quantities of a certain material which have the deep interference minima in its total neutron cross-section. By transmitting reactor neutrons through bulk layer of such material, one can obtain the quasimonochromatic neutron lines instead of white reactor spectrum.

The history of permanent magnet materials

International Nuclear Information System (INIS)

Livingston, J.D.

1990-01-01

Permanent-magnet materials play a large and growing, but largely unseen, role in today's technology. Many common devices in the home and elsewhere, including appliances, computers and printers, contain permanent-magnet motors and actuators. The growth of applications for permanent magnets results in large part from the improvements in magnetic properties, which allow the engineer to design smaller, lighter and more efficient devices. The properties of the greatest technological interest are remanence, coercivity and maximum energy product. All are non-equilibrium and high structure-sensitive. Coercivity is particularly sensitive to microstructure, while remanence is sensitive to texture (crystallographic alignment). The energy product depends on both coercivity and remanence. The more than one hundredfold increase in the available energy product in this century, and the corresponding amount of magnet required for a specific application, are shown

Comparison of the image qualities of filtered back-projection, adaptive statistical iterative reconstruction, and model-based iterative reconstruction for CT venography at 80 kVp

International Nuclear Information System (INIS)

Kim, Jin Hyeok; Choo, Ki Seok; Moon, Tae Yong; Lee, Jun Woo; Jeon, Ung Bae; Kim, Tae Un; Hwang, Jae Yeon; Yun, Myeong-Ja; Jeong, Dong Wook; Lim, Soo Jin

2016-01-01

To evaluate the subjective and objective qualities of computed tomography (CT) venography images at 80 kVp using model-based iterative reconstruction (MBIR) and to compare these with those of filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR) using the same CT data sets. Forty-four patients (mean age: 56.1 ± 18.1) who underwent 80 kVp CT venography (CTV) for the evaluation of deep vein thrombosis (DVT) during 4 months were enrolled in this retrospective study. The same raw data were reconstructed using FBP, ASIR, and MBIR. Objective and subjective image analysis were performed at the inferior vena cava (IVC), femoral vein, and popliteal vein. The mean CNR of MBIR was significantly greater than those of FBP and ASIR and images reconstructed using MBIR had significantly lower objective image noise (p <.001). Subjective image quality and confidence of detecting DVT by MBIR group were significantly greater than those of FBP and ASIR (p <.005), and MBIR had the lowest score for subjective image noise (p <.001). CTV at 80 kVp with MBIR was superior to FBP and ASIR regarding subjective and objective image qualities. (orig.)

Miniaturized dielectric waveguide filters

OpenAIRE

Sandhu, MY; Hunter, IC

2016-01-01

Design techniques for a new class of integrated monolithic high-permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled transverse electromagnetic filters with the same unloaded Q-factor. Designs for Chebyshev and asymmetric generalised Chebyshev filter and a diplexer are presented with experimental results for an 1800 MHz Chebyshev filter and a 1700 MHz generalised Chebyshev filter showing excellent agreement with theory.

Concrete ensemble Kalman filters with rigorous catastrophic filter divergence.

Science.gov (United States)

Kelly, David; Majda, Andrew J; Tong, Xin T

2015-08-25

The ensemble Kalman filter and ensemble square root filters are data assimilation methods used to combine high-dimensional, nonlinear dynamical models with observed data. Ensemble methods are indispensable tools in science and engineering and have enjoyed great success in geophysical sciences, because they allow for computationally cheap low-ensemble-state approximation for extremely high-dimensional turbulent forecast models. From a theoretical perspective, the dynamical properties of these methods are poorly understood. One of the central mysteries is the numerical phenomenon known as catastrophic filter divergence, whereby ensemble-state estimates explode to machine infinity, despite the true state remaining in a bounded region. In this article we provide a breakthrough insight into the phenomenon, by introducing a simple and natural forecast model that transparently exhibits catastrophic filter divergence under all ensemble methods and a large set of initializations. For this model, catastrophic filter divergence is not an artifact of numerical instability, but rather a true dynamical property of the filter. The divergence is not only validated numerically but also proven rigorously. The model cleanly illustrates mechanisms that give rise to catastrophic divergence and confirms intuitive accounts of the phenomena given in past literature.

6 CFR 7.29 - Documents of permanent historical value.

Science.gov (United States)

2010-01-01

... 6 Domestic Security 1 2010-01-01 2010-01-01 false Documents of permanent historical value. 7.29... NATIONAL SECURITY INFORMATION Classified Information § 7.29 Documents of permanent historical value. The... contained in records determined to have permanent historical value under 44 U.S.C. 2107 before they are...

Hybrid Filter Membrane

Science.gov (United States)

Laicer, Castro; Rasimick, Brian; Green, Zachary

2012-01-01

Cabin environmental control is an important issue for a successful Moon mission. Due to the unique environment of the Moon, lunar dust control is one of the main problems that significantly diminishes the air quality inside spacecraft cabins. Therefore, this innovation was motivated by NASA s need to minimize the negative health impact that air-suspended lunar dust particles have on astronauts in spacecraft cabins. It is based on fabrication of a hybrid filter comprising nanofiber nonwoven layers coated on porous polymer membranes with uniform cylindrical pores. This design results in a high-efficiency gas particulate filter with low pressure drop and the ability to be easily regenerated to restore filtration performance. A hybrid filter was developed consisting of a porous membrane with uniform, micron-sized, cylindrical pore channels coated with a thin nanofiber layer. Compared to conventional filter media such as a high-efficiency particulate air (HEPA) filter, this filter is designed to provide high particle efficiency, low pressure drop, and the ability to be regenerated. These membranes have well-defined micron-sized pores and can be used independently as air filters with discreet particle size cut-off, or coated with nanofiber layers for filtration of ultrafine nanoscale particles. The filter consists of a thin design intended to facilitate filter regeneration by localized air pulsing. The two main features of this invention are the concept of combining a micro-engineered straight-pore membrane with nanofibers. The micro-engineered straight pore membrane can be prepared with extremely high precision. Because the resulting membrane pores are straight and not tortuous like those found in conventional filters, the pressure drop across the filter is significantly reduced. The nanofiber layer is applied as a very thin coating to enhance filtration efficiency for fine nanoscale particles. Additionally, the thin nanofiber coating is designed to promote capture of

Laced permanent magnet quadrupole drift tube magnets

International Nuclear Information System (INIS)

Feinberg, B.; Behrsing, G.U.; Halbach, K.; Marks, J.S.; Morrison, M.E.; Nelson, D.H.

1988-10-01

A laced permanent magnet quadrupole drift tube magnet has been constructed for a proof-of-principle test. The magnet is a conventional tape-wound quadrupole electromagnet, using iron pole- pieces, with the addition of permanent magnet material (neodymium iron) between the poles to reduce the effects of saturation. The iron is preloaded with magnetic flux generated by the permanent magnet material, resulting in an asymmetrical saturation curve. Since the polarity of the quadrupole magnets in a drift tube linac is not reversed we can take advantage of this asymmetrical saturation to provide greater focusing strength. The magnet configuration has been optimized and the vanadium permendur poles needed in a conventional quadrupole have been replaced with iron poles. The use of permanent magnet material has allowed us to increase the focusing strength of the magnet by about 20% over that of a conventional tape-wound quadrupole. Comparisons will be made between this magnet and the conventional tape-wound quadrupole. 3 refs., 5 figs

Micromagnetics of rare-earth efficient permanent magnets

Science.gov (United States)

Fischbacher, Johann; Kovacs, Alexander; Gusenbauer, Markus; Oezelt, Harald; Exl, Lukas; Bance, Simon; Schrefl, Thomas

2018-05-01

The development of permanent magnets containing less or no rare-earth elements is linked to profound knowledge of the coercivity mechanism. Prerequisites for a promising permanent magnet material are a high spontaneous magnetization and a sufficiently high magnetic anisotropy. In addition to the intrinsic magnetic properties the microstructure of the magnet plays a significant role in establishing coercivity. The influence of the microstructure on coercivity, remanence, and energy density product can be understood by using micromagnetic simulations. With advances in computer hardware and numerical methods, hysteresis curves of magnets can be computed quickly so that the simulations can readily provide guidance for the development of permanent magnets. The potential of rare-earth reduced and rare-earth free permanent magnets is investigated using micromagnetic simulations. The results show excellent hard magnetic properties can be achieved in grain boundary engineered NdFeB, rare-earth magnets with a ThMn12 structure, Co-based nano-wires, and L10-FeNi provided that the magnet’s microstructure is optimized.

Variable Permanent Magnet Quadrupole

International Nuclear Information System (INIS)

Mihara, T.; Iwashita, Y.; Kyoto U.; Kumada, M.; NIRS, Chiba; Spencer, C.M.; SLAC

2007-01-01

A permanent magnet quadrupole (PMQ) is one of the candidates for the final focus lens in a linear collider. An over 120 T/m strong variable permanent magnet quadrupole is achieved by the introduction of saturated iron and a 'double ring structure'. A fabricated PMQ achieved 24 T integrated gradient with 20 mm bore diameter, 100 mm magnet diameter and 20 cm pole length. The strength of the PMQ is adjustable in 1.4 T steps, due to its 'double ring structure': the PMQ is split into two nested rings; the outer ring is sliced along the beam line into four parts and is rotated to change the strength. This paper describes the variable PMQ from fabrication to recent adjustments

U.S. Lawful Permanent Residents: Fiscal Year 2014

Data.gov (United States)

Department of Homeland Security — Lawful permanent residents (LPRs), also known as “green card” holders, are non-citizens who are lawfully authorized to live permanently within the United States.

Sampled data CT system including analog filter and compensating digital filter

International Nuclear Information System (INIS)

Glover, G. H.; DallaPiazza, D. G.; Pelc, N. J.

1985-01-01

A CT scanner in which the amount of x-ray information acquired per unit time is substantially increased by using a continuous-on x-ray source and a sampled data system with the detector. An analog filter is used in the sampling system for band limiting the detector signal below the highest frequency of interest, but is a practically realizable filter and is therefore non-ideal. A digital filter is applied to the detector data after digitization to compensate for the characteristics of the analog filter, and to provide an overall filter characteristic more nearly like the ideal

U.S. Lawful Permanent Residents: Fiscal Year 2013

Data.gov (United States)

Department of Homeland Security — A lawful permanent resident (LPR) or 'green card' recipient is defined by immigration law as a person who has been granted lawful permanent residence in the United...

Quick-change filter cartridge

Science.gov (United States)

Rodgers, John C.; McFarland, Andrew R.; Ortiz, Carlos A.

1995-01-01

A quick-change filter cartridge. In sampling systems for measurement of airborne materials, a filter element is introduced into the sampled airstream such that the aerosol constituents are removed and deposited on the filter. Fragile sampling media often require support in order to prevent rupture during sampling, and careful mounting and sealing to prevent misalignment, tearing, or creasing which would allow the sampled air to bypass the filter. Additionally, handling of filter elements may introduce cross-contamination or exposure of operators to toxic materials. Moreover, it is desirable to enable the preloading of filter media into quick-change cartridges in clean laboratory environments, thereby simplifying and expediting the filter-changing process in the field. The quick-change filter cartridge of the present invention permits the application of a variety of filter media in many types of instruments and may also be used in automated systems. The cartridge includes a base through which a vacuum can be applied to draw air through the filter medium which is located on a porous filter support and held there by means of a cap which forms an airtight seal with the base. The base is also adapted for receiving absorbing media so that both particulates and gas-phase samples may be trapped for investigation, the latter downstream of the aerosol filter.

OAS :: Authorities : Permanent Representatives to the OAS

Science.gov (United States)

Rights Actions against Corruption C Children Civil Registry Civil Society Contact Us Culture Cyber Representative of Belize Diego Pary Rodríguez Bolivia Diego Pary Rodríguez Ambassador, Permanent Representative of Bolivia José Luiz Machado Brazil José Luiz Machado e Costa Ambassador, Permanent Representative

Improved Kalman Filter-Based Speech Enhancement with Perceptual Post-Filtering

Institute of Scientific and Technical Information of China (English)

WEIJianqiang; DULimin; YANZhaoli; ZENGHui

2004-01-01

In this paper, a Kalman filter-based speech enhancement algorithm with some improvements of previous work is presented. A new technique based on spectral subtraction is used for separation speech and noise characteristics from noisy speech and for the computation of speech and noise Autoregressive (AR) parameters. In order to obtain a Kalman filter output with high audible quality, a perceptual post-filter is placed at the output of the Kalman filter to smooth the enhanced speech spectra.Extensive experiments indicate that this newly proposed method works well.

Static devices with new permanent magnets

International Nuclear Information System (INIS)

Chavanne, J.; Laforest, J.; Pauthenet, R.

1987-01-01

The high remanence and coercivity of the new permanent magnet materials are of special interest in the static applications. High ordering temperature and are uniaxial anisotropy at the origin of their good permanent magnet properties are obtained in rare earth-transition metal compounds. Binary SmCo/sub 5/ and Sm/sub 2/Co/sub 17/ and ternary Nd/sub 2/Fe/sub 14/B compounds are the basis materials of the best permanent magnets. new concepts of calculations of static devices with these magnets can be applied: the magnetization can be considered as ridig, the density of the surface Amperian current is constant, the relative permeability is approximately 1 and the induction calculations are linear. Examples of hexapoles with Sm-Co and NdFeB magnets are described and the performances are compared. The problems of temperature behavior and corrosion resistance are underlined

U.S. Legal Permanent Residents: Fiscal Year 2007

Data.gov (United States)

Department of Homeland Security — A legal permanent resident (LPR) or “green card” recipient is defined by immigration law as a person who has been granted lawful permanent residence in the United...

U.S. Legal Permanent Residents: Fiscal Year 2010

Data.gov (United States)

Department of Homeland Security — A legal permanent resident (LPR) or “green card” recipient is defined by immigration law as a person who has been granted lawful permanent residence in the United...

U.S. Legal Permanent Residents: Fiscal Year 2008

Data.gov (United States)

Department of Homeland Security — A legal permanent resident (LPR) or “green card” recipient is defined by immigration law as a person who has been granted lawful permanent residence in the United...

U.S. Legal Permanent Residents: Fiscal Year 2012

Data.gov (United States)

Department of Homeland Security — A legal permanent resident (LPR) or “green card” recipient is defined by immigration law as a person who has been granted lawful permanent residence in the United...

Samarium-cobalt type rare earth permanent magnets

International Nuclear Information System (INIS)

Kamat, S.V.

2014-01-01

Permanent magnets are one of the oldest and largest applications of magnetic materials and form an integral part of our modern industrial society. They belong to a special class of functional materials and are characterized for remanence (flux output from the magnet), coercivity (resistance to demagnetization) and energy product (material energy density) from the second quadrant of the magnetic hysteresis loop. The reliability, stability, size, weight, cost and performance of many electro-technical devices depend mainly on the properties of permanent magnets used in them. There are three important families of permanent magnets viz., Ferrites, Alnicos and Rare Earth Permanent Magnets (REPMs) with energy product values ranging from 3 to 50 MGOe and among the front ranking high performance REPMs, SmCo 5 , Sm 2 Co 17 type and NdFeB alloys are technologically the most important materials. They are used in a wide range of applications ranging from consumer products to very specialized areas of tele-communications, microelectronics, defence, space, avionics etc. While NdFeB has the highest energy product, Sm-Co based magnets are preferred for most critical applications where temperature stability of magnetic properties is essential because of their significantly higher Curie temperatures. In this presentation some of the key challenges associated with these Sm-Co based rare earth permanent magnets will be highlighted. (author)

Method for cleaning the filter pockets of dust gas filter systems

Energy Technology Data Exchange (ETDEWEB)

Margraf, A

1975-05-07

The invention deals with a method to clean filter pockets filled with dust gas. By a periodic to and fro air jet attached to a scavenging blower, a pulsed fluttering movement of the filter surface is obtained which releases the outer layers of dust. The charging of the filter pockets with scavenging air to clean the filter material can be carried out immediately on the pulsed admission with suitable time control.

A Digital Image Denoising Algorithm Based on Gaussian Filtering and Bilateral Filtering

Directory of Open Access Journals (Sweden)

Piao Weiying

2018-01-01

Full Text Available Bilateral filtering has been applied in the area of digital image processing widely, but in the high gradient region of the image, bilateral filtering may generate staircase effect. Bilateral filtering can be regarded as one particular form of local mode filtering, according to above analysis, an mixed image de-noising algorithm is proposed based on Gaussian filter and bilateral filtering. First of all, it uses Gaussian filter to filtrate the noise image and get the reference image, then to take both the reference image and noise image as the input for range kernel function of bilateral filter. The reference image can provide the image’s low frequency information, and noise image can provide image’s high frequency information. Through the competitive experiment on both the method in this paper and traditional bilateral filtering, the experimental result showed that the mixed de-noising algorithm can effectively overcome staircase effect, and the filtrated image was more smooth, its textural features was also more close to the original image, and it can achieve higher PSNR value, but the amount of calculation of above two algorithms are basically the same.

Filtering Photogrammetric Point Clouds Using Standard LIDAR Filters Towards DTM Generation

Science.gov (United States)

Zhang, Z.; Gerke, M.; Vosselman, G.; Yang, M. Y.

2018-05-01

Digital Terrain Models (DTMs) can be generated from point clouds acquired by laser scanning or photogrammetric dense matching. During the last two decades, much effort has been paid to developing robust filtering algorithms for the airborne laser scanning (ALS) data. With the point cloud quality from dense image matching (DIM) getting better and better, the research question that arises is whether those standard Lidar filters can be used to filter photogrammetric point clouds as well. Experiments are implemented to filter two dense matching point clouds with different noise levels. Results show that the standard Lidar filter is robust to random noise. However, artefacts and blunders in the DIM points often appear due to low contrast or poor texture in the images. Filtering will be erroneous in these locations. Filtering the DIM points pre-processed by a ranking filter will bring higher Type II error (i.e. non-ground points actually labelled as ground points) but much lower Type I error (i.e. bare ground points labelled as non-ground points). Finally, the potential DTM accuracy that can be achieved by DIM points is evaluated. Two DIM point clouds derived by Pix4Dmapper and SURE are compared. On grassland dense matching generates points higher than the true terrain surface, which will result in incorrectly elevated DTMs. The application of the ranking filter leads to a reduced bias in the DTM height, but a slightly increased noise level.

Bias aware Kalman filters

DEFF Research Database (Denmark)

Drecourt, J.-P.; Madsen, H.; Rosbjerg, Dan

2006-01-01

This paper reviews two different approaches that have been proposed to tackle the problems of model bias with the Kalman filter: the use of a colored noise model and the implementation of a separate bias filter. Both filters are implemented with and without feedback of the bias into the model state....... The colored noise filter formulation is extended to correct both time correlated and uncorrelated model error components. A more stable version of the separate filter without feedback is presented. The filters are implemented in an ensemble framework using Latin hypercube sampling. The techniques...... are illustrated on a simple one-dimensional groundwater problem. The results show that the presented filters outperform the standard Kalman filter and that the implementations with bias feedback work in more general conditions than the implementations without feedback. 2005 Elsevier Ltd. All rights reserved....

Study of different filters

International Nuclear Information System (INIS)

Cochinal, R.; Rouby, R.

1959-01-01

This note first contains a terminology related to filters and to their operation, and then proposes an overview of general characteristics of filters such as load loss with respect to gas rate, efficiency, and clogging with respect to filter pollution. It also indicates standard aerosols which are generally used, how they are dosed, and how efficiency is determined with a standard aerosol. Then, after a presentation of the filtration principle, this note reports the study of several filters: glass wool, filter papers provided by different companies, Teflon foam, English filters, Teflon wool, sintered Teflonite, quartz wool, polyvinyl chloride foam, synthetic filter, sintered bronze. The third part reports the study of some aerosol and dust separators

Numerical Study on Self-Cleaning Canister Filter With Add-On Filter Cap

Directory of Open Access Journals (Sweden)

Mohammed Akmal Nizam

2017-01-01

Full Text Available Filtration in a turbo machinery system such as a gas turbine will ensure that the air entering the inlet is free from contaminants that could bring damage to the main system. Self-cleaning filter systems for gas turbines are designed for continuously efficient flow filtration. A good filter would be able to maintain its effectiveness over a longer time period, prolonging the duration between filter replacements and providing lower pressure drop over its operating lifetime. With this goal in mind, the current study is focused on the difference in pressure loss of the benchmark Salutary Avenue Self-cleaning filter in comparison to a new design with an add-on filter cap. Geometry for the add-on filter cap will be based from Salutary Avenue Manufacturing Sdn.Bhd. SOLIDWORKS software was used to model the geometry of the filter, while simulation analysis on the flow through the filter was done using Computational Fluid Dynamic (CFD software. The simulations are based on a low velocity condition, in which the parameter for the inlet velocity are set at 0.032 m/s, 0.063 m/s, 0.094 m/s and 0.126 m/s respectively. From the simulation data obtained for the inlet velocities considered, the pressure drop reduction of the modified filter compared to the benchmark was found to be between 7.59% and 30.18%. All in all, the modification of the filter cap produced a lower pressure drop in comparison with the benchmark filter; an improvement of 27.02% for the total pressure drop was obtained.

Laboratory for filter testing

Energy Technology Data Exchange (ETDEWEB)

Paluch, W.

1987-07-01

Filters used for mine draining in brown coal surface mines are tested by the Mine Draining Department of Poltegor. Laboratory tests of new types of filters developed by Poltegor are analyzed. Two types of tests are used: tests of scale filter models and tests of experimental units of new filters. Design and operation of the test stands used for testing mechanical properties and hydraulic properties of filters for coal mines are described: dimensions, pressure fluctuations, hydraulic equipment. Examples of testing large-diameter filters for brown coal mines are discussed.

Milton Friedman and the Emergence of the Permanent Income Hypothesis

OpenAIRE

Hsiang-Ke Chao

2001-01-01

The purpose of this paper is to investigate the evolution of MiltonFriedman's permanent income hypothesis from the 1940s to 1960s, andhow it became the paradigm of modern consumption theory. Modellingunobservables, such as permanent income and permanent consumption, isa long-standing issue in economics and econometrics. While theconventional approach has been to set an empirical model to make"permanent income" measurable, the historical change in the meaningof that theoretical construct is al...

Simulasi Filter Pasif Dan Perbandingan Unjuk Kerjanya Dengan Filter Aktif Dan Filter Aktif Hibrid Dalam Meredam Harmonisa Pada Induction Furnace

OpenAIRE

Tanoto, Yusak; Limantara, Limboto; Khandy Lestanto, Khristian

2005-01-01

This paper describe about simulation of Passive Filter in analysis to reduce harmonics that happened in a load such as vacuum casting induction furnace 9 kW, 13.8 kVA, 200V, 3 Ph, 50/60 Hz, also gives comparison with Hybrid Active Filter and Active Filter which made satisfaction result on the previous research. The best result achieved on the use of Hybrid Active Filter on %ITHD for 4.27 % and %VTHD for 3.83%, while Active Filter gave on %ITHD for 5.14 % and %VTHD for 3.82%. There ...

Hydrogen stability of SmCo5 permanent magnet

International Nuclear Information System (INIS)

Lukin, A.; Rabinovich, Y.; Bala, H.

2001-01-01

The present work has been performed with purpose to determine the level of hydrogen stability of sintered SmCo 5 permanent magnets by means of accelerated tests, to study the effect of hydrogen on the magnetic and mechanical properties of the permanent magnets and to establish the criteria of hydrogenation level and the activation energy of this process. In addition, the effect of hydrogen on the properties of sintered SmCo 5 permanent magnets in specific conditions of exploitation and storage durability of instruments was studied

Rotation speed measurement for turbine governor: torsion filtering by using Kalman filter

International Nuclear Information System (INIS)

Houry, M.P.; Bourles, H.

1996-01-01

The rotation speed of a turbogenerator is disturbed by its shaft torsion. Obtaining a filtered measure of this speed is a problem of a great practical importance for turbine governor. A good filtering of this speed must meet two requirements: it must cut frequencies of the shaft torsion oscillation and it must not reduce or delay the signal in the pass-band, i.e. at lower frequencies. At Electricite de France, the speed measure is used to set in motion the fast valving system as quickly as possible, after a short circuit close to the unit or rather an islanding. It is difficult to satisfy these two requirements by using conventional filtering methods. The standard solution consists in a first order filter: at Electricite de France, its time constant is equal to 80 ms. We have decided to improve this filtering by designing a new filter which cuts the frequencies of the shaft torsion oscillation without reducing the bandwidth to the speed measure. If one uses conventional methods to obtain a band stop filter, it is easy to obtain the desired magnitude but not a phase near zero in the whole pass-band. Therefore, we have chosen to design the filter by using Kalman'a theory. The measurement noise is modeled as a colored one, generated by a very lightly damped system driven by a while noise. The resulting Kalman filter is an effective band stop filter, whose phase nicely remains near zero in the whole pass-band. The digital simulations we made and the tests we carried out with the Electricite de France Micro Network laboratory show the advantages of the rotation speed filter we designed using Kalman's theory. With the proposed filter, the speed measure filtering is better in terms of reduction and phase shift. the result is that there are less untimely solicitations of the fast valving system. Consequently, this device improves the power systems stability by minimizing the risks of deep perturbations due to a temporary lack of generation and the risks of under-speed loss

The dry filter method for passive filtered venting of the containment

International Nuclear Information System (INIS)

Freis, Daniel; Tietsch, Wolfgang; Obenland, Ralf; Kroes, Bert; Martinsteg, Hans

2013-01-01

Filtered Venting is a mitigative emergency measure to protect the containment from pressure failure in case of a severe accident. Filtered vent systems which are based on the Dry Filter Method (DFM) are proven technology, work completely passive, meet all functional requirements and show excellent performance with respect to filter efficiency. With such a system the release of radioactive fission products to the environment can be effectively minimized. Short and long term land contaminations can be avoided. (orig.)

Elective extractions of first permanent molars: a review

Directory of Open Access Journals (Sweden)

Melike Kiraz

2018-05-01

Full Text Available Permanent first molar teeth possess a key role in the setting-up of the occlusion, contribute significantly to the chewing function and serve as a guide for other teeth. However, it is frequently encountered that permanent first molar teeth are extracted due to the predicted negative prognoses of caries or developmental defects. As a result of the uncontrolled extraction of the permanent first molar teeth during the growth and development period, drifting of adjacent teeth, continued eruption of the opposing teeth and displacements can be seen. Furthermore, following one-sided extraction, midline deviations, oppositional tooth eruption, skeletal and dental asymmetry, unilateral chewing habits, and temporo-mandibular joint disorders may occur. To prevent these pathological conditions and to maintain the stability of the occlusal relation, it is necessary to do compensation and balancing extractions of the permanent first molar teeth on the opposite/symmetric arc, assuming mesial drag of the permanent second and third molar teeth. With such controlled-extractions, especially in Class I cases, orthodontic or prosthetic treatments, which may require extra time, cost and effort, could be prevented and a conceivable occlusion can be established.

Generalized Selection Weighted Vector Filters

Directory of Open Access Journals (Sweden)

Rastislav Lukac

2004-09-01

Full Text Available This paper introduces a class of nonlinear multichannel filters capable of removing impulsive noise in color images. The here-proposed generalized selection weighted vector filter class constitutes a powerful filtering framework for multichannel signal processing. Previously defined multichannel filters such as vector median filter, basic vector directional filter, directional-distance filter, weighted vector median filters, and weighted vector directional filters are treated from a global viewpoint using the proposed framework. Robust order-statistic concepts and increased degree of freedom in filter design make the proposed method attractive for a variety of applications. Introduced multichannel sigmoidal adaptation of the filter parameters and its modifications allow to accommodate the filter parameters to varying signal and noise statistics. Simulation studies reported in this paper indicate that the proposed filter class is computationally attractive, yields excellent performance, and is able to preserve fine details and color information while efficiently suppressing impulsive noise. This paper is an extended version of the paper by Lukac et al. presented at the 2003 IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing (NSIP '03 in Grado, Italy.

PENGUKURAN PERMANENT EARNINGS PADA HUBUNGAN DENGAN KEBIJAKAN DIVIDEND PERUSAHAAN : REVIEW PENELITIAN

Directory of Open Access Journals (Sweden)

Wahyu Manuhara Putra

2016-02-01

Full Text Available Corporate earnings divided into a permanent component of earnings and transitory earnings will be very useful in estimating the future value of the company, that will be useful in decision making stock return. Be more relevant for investors and financial analysts in analyzing the earnings based on the permanent and transitory earnings. On permanent earnings will be more focused to get the gain from investments. One focus of research is based on this component is to test the relationship with the earnings dividend payment policy. Based on several studies obtained different results concerning the relationship with the permanent earnings dividend policy. Research that focuses on permanent earnings using two approaches to determine the accuracy of the proxy of permanent earnings. Determination of permanent earnings through the stock price and the latter by using the accounting profit.

Rotation speed measurement for turbine governor: torsion filtering by using Kalman filter

International Nuclear Information System (INIS)

Houry, M.P.; Bourles, H.

1995-11-01

The rotation speed of a turbogenerator is disturbed by its shaft torsion. Obtaining a filtered measure of this sped a problem of a great practical importance for turbine governor. A good filtering of this speed must meet two requirements: it must cut frequencies of the shaft torsion oscillation and it must not reduce or delay the signal in the pass-band. i.e. at lower frequencies. At Electricite de France, the speed measure is used to set in motion the fast valving system as quickly as possible, after a short circuit close to the unit (to contribute to the stability) or after an islanding (to quickly reach a balance with the house load). It is difficult to satisfy these two requirements by using conventional filtering methods. The standard solution consists in a first order filter: at Electricite de France, its time constant is equal to 80 ms; We have decided to improve this filtering by designing a new filter which cuts the frequencies of the shaft torsion oscillation without reducing the bandwidth of the speed measure. If one uses conventional methods to obtain a band-stop filter (for instance a Butterworth, a Chebyshev or an elliptic band-stop filter),it is easy to obtain the desired magnitude but not a phase near zero in the whole pass-band. Therefore, we have chosen to design the filter by using Kalman's theory. The measurement noise is modeled as a colored one, generated by a very lightly damped system driven by a white noise. The resulting Kalman filter is an effective band-stop filter, whose phase nicely remains near zero in the whole pass-band. (authors). 13 refs., 12 figs

76 FR 78698 - Proposed Revocation of Permanent Variances

Science.gov (United States)

2011-12-19

... Administration (``OSHA'' or ``the Agency'') granted permanent variances to 24 companies engaged in the... DEPARTMENT OF LABOR Occupational Safety and Health Administration [Docket No. OSHA-2011-0054] Proposed Revocation of Permanent Variances AGENCY: Occupational Safety and Health Administration (OSHA...

Permanent magnet based dipole magnets for next generation light sources

Directory of Open Access Journals (Sweden)

Takahiro Watanabe

2017-07-01

Full Text Available We have developed permanent magnet based dipole magnets for the next generation light sources. Permanent magnets are advantageous over electromagnets in that they consume less power, are physically more compact, and there is a less risk of power supply failure. However, experience with electromagnets and permanent magnets in the field of accelerators shows that there are still challenges to replacing main magnets of accelerators for light sources with permanent magnets. These include the adjustability of the magnetic field, the temperature dependence of permanent magnets, and the issue of demagnetization. In this paper, we present a design for magnets for future light sources, supported by experimental and numerical results.

Optimization of filter loading

International Nuclear Information System (INIS)

Turney, J.H.; Gardiner, D.E.; Sacramento Municipal Utility District, Herald, CA)

1985-01-01

The introduction of 10 CFR Part 61 has created potential difficulties in the disposal of spent cartridge filters. When this report was prepared, Rancho Seco had no method of packaging and disposing of class B or C filters. This work examined methods to minimize the total operating cost of cartridge filters while maintaining them below the class A limit. It was found that by encapsulating filters in cement the filter operating costs could be minimized

Permanent tracheostomy: Its social impacts and their management ...

African Journals Online (AJOL)

Background: Upper respiratory tract obstruction resulting from bilateral recurrent laryngeal nerve damage is commonly managed with permanent tracheostomy in our environment. Objective: To evaluate the social impacts of permanent tracheostomy and its management in Ondo State, Southwest Nigeria. Materials and ...

Retrievable Vena Cava Filters in Major Trauma Patients: Prevalence of Thrombus Within the Filter

International Nuclear Information System (INIS)

Mahrer, Arie; Zippel, Douglas; Garniek, Alexander; Golan, Gil; Bensaid, Paul; Simon, Daniel; Rimon, Uri

2008-01-01

The purpose of this study was to report the prevalence of thrombus within a retrievable vena cava filter inserted prophylactically in major trauma patients referred for filter extraction. Between November 2002 and August 2005, 80 retrievable inferior vena cava filters (68 Optease and 12 Gunther-Tulip) were inserted into critically injured trauma patients (mean injury severity score 33.5). The filters were inserted within 1 to 6 (mean 2) days of injury. Thirty-seven patients were referred for filter removal (32 with Optease and 5 with Gunther-Tulip). The indwelling time was 7 to 22 (mean 13) days. All patients underwent inferior vena cavography prior to filter removal. There were no insertion-related complications and all filters were successfully deployed. Forty-three (54%) of the 80 patients were not referred for filter removal, as these patients continued to have contraindications to anticoagulation. Thirty-seven patients (46%) were referred for filter removal. In eight of them (22%) a large thrombus was seen within the filters and they were left in place, all with the Optease device. The other 29 filters (36%) were removed uneventfully.We conclude that the relatively high prevalence of intrafilter thrombi with the Optease filter may be explained by either spontaneous thrombus formation or captured emboli.

Physical characteristics of the paper filter and low cafestol content filter coffee brews.

Science.gov (United States)

Rendón, Mery Yovana; Dos Santos Scholz, Maria Brígida; Bragagnolo, Neura

2018-06-01

The results found in the literature concerning the effect of consuming filter coffee brews on increasing the blood cholesterol levels due to the presence of diterpenes, are divergent. Thus the present research evaluated the diterpene (cafestol and kahweol) concentrations in filter coffee brews prepared with paper filters of different sizes, colors and origins (Brazil, Japan, The United States of America, Germany, France and the Netherlands), with and without micro perforations. This is the first study that reports the physical characteristics of paper filter and its importance to obtain filter coffee brew with low cafestol content. Thus, a sample of Catuai cultivar coffee with high cafestol content was roasted to a medium-light degree and used to prepare the brews in a 1:10 ratio (coffee powder to water). The diterpenes were extracted by direct saponification and quantified and identified by HPLC-DAD-MS/MS. The paper filters were physically characterized by measuring their grammage, and the fat permeation rate calculated in order to better understand the differences between the filters which allow one to obtain higher or lower diterpene contents. The cafestol and kahweol concentrations in the brews varied from 1.62 to 2.98 mg/L and from 0.73 to 1.96 mg/L, respectively. The highest cafestol and kahweol concentrations were obtained using paper filters with micro perforations, considering similar sized paper filters. The paper filters showed high fat permeability and grammages between 50.46 and 67.48 g/m 2 . The diterpene retention capacities of the filters produced in the different countries were similar. The results showed that the porosity of the paper filter and the particle size of the ground roasted coffee were determinant factors in obtaining filter coffee brews with lower cafestol contents. Copyright © 2018 Elsevier Ltd. All rights reserved.

Special-Purpose High-Torque Permanent-Magnet Motors

Science.gov (United States)

Doane, George B., III

1995-01-01

Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.

Modeling demagnetization effects in permanent magnet synchronous machines

NARCIS (Netherlands)

Kral, C.; Sprangers, R.L.J.; Waarma, J.; Haumer, A.; Winter, O.; Lomonova, E.

2010-01-01

This paper presents a permanent magnet model which takes temperature dependencies and demagnetization effects into account. The proposed model is integrated into a magnetic fundamental wave machine model using the model- ing language Modelica. For different rotor types permanent magnet models are

Modeling of ironless permanent magnet planar motor structures

NARCIS (Netherlands)

Boeij, de J.; Lomonova, E.A.; Vandenput, A.J.A.

2006-01-01

This paper describes an analytical model that includes end effects for ironless synchronous permanent-magnet planar actuators. Because of its flexibility, the model can be used to predict the performance of various permanent-magnet array and coil array topologies and commutation schemes. Moreover,

Design, control, and implementation of LCL-filter-based shunt active power filters

DEFF Research Database (Denmark)

Tang, Yi; Loh, Poh Chiang; Wang, Peng

2011-01-01

This paper concentrates on the design, control and implementation of an LCL-filter-based shunt active power filter (SAPF), which can effectively compensate harmonic currents produced by nonlinear loads in a three-phase three-wire power system. The use of LCL-filter at the output end of SAPF offer......-loop control system, and active damping implemented with fewer current sensors are all addressed here. An analytical design example is finally presented, being supported with experimental results, to verify its effectiveness and practicality.......This paper concentrates on the design, control and implementation of an LCL-filter-based shunt active power filter (SAPF), which can effectively compensate harmonic currents produced by nonlinear loads in a three-phase three-wire power system. The use of LCL-filter at the output end of SAPF offers...

Inorganic UV filters

Directory of Open Access Journals (Sweden)

Eloísa Berbel Manaia

2013-06-01

Full Text Available Nowadays, concern over skin cancer has been growing more and more, especially in tropical countries where the incidence of UVA/B radiation is higher. The correct use of sunscreen is the most efficient way to prevent the development of this disease. The ingredients of sunscreen can be organic and/or inorganic sun filters. Inorganic filters present some advantages over organic filters, such as photostability, non-irritability and broad spectrum protection. Nevertheless, inorganic filters have a whitening effect in sunscreen formulations owing to the high refractive index, decreasing their esthetic appeal. Many techniques have been developed to overcome this problem and among them, the use of nanotechnology stands out. The estimated amount of nanomaterial in use must increase from 2000 tons in 2004 to a projected 58000 tons in 2020. In this context, this article aims to analyze critically both the different features of the production of inorganic filters (synthesis routes proposed in recent years and the permeability, the safety and other characteristics of the new generation of inorganic filters.

Particle Kalman Filtering: A Nonlinear Framework for Ensemble Kalman Filters

KAUST Repository

Hoteit, Ibrahim

2010-09-19

Optimal nonlinear filtering consists of sequentially determining the conditional probability distribution functions (pdf) of the system state, given the information of the dynamical and measurement processes and the previous measurements. Once the pdfs are obtained, one can determine different estimates, for instance, the minimum variance estimate, or the maximum a posteriori estimate, of the system state. It can be shown that, many filters, including the Kalman filter (KF) and the particle filter (PF), can be derived based on this sequential Bayesian estimation framework. In this contribution, we present a Gaussian mixture‐based framework, called the particle Kalman filter (PKF), and discuss how the different EnKF methods can be derived as simplified variants of the PKF. We also discuss approaches to reducing the computational burden of the PKF in order to make it suitable for complex geosciences applications. We use the strongly nonlinear Lorenz‐96 model to illustrate the performance of the PKF.

[Object permanence in children with neurological and psychomotor disorders].

Science.gov (United States)

Pisaturo, C; Frassoni, S; Borreani, A; Battaglia, F; Meruzzi, B

1995-06-01

The aim of this research was to investigate whether the development of object permanence is an available sign of the cognitive development in infants with psychomotor handicaps. Subjects consisted of 5 males, ranging in age from 12 to 33 months, with handicaps as a result of perinatal brain injury. Four were preterm infants. All of the children received psychomotor treatment. Their stage of object permanence was assessed using traditional (B-L) and non traditional test (U-H). (The children's performances on the U-H scales have an "Intrinsic validity"). Four children achieved the first stages of the development of object permanence. The acquisition of object permanence was delayed in comparison with the age-appropriated time, but it may be considered adequate in comparison with the "developmental age" (B-L). One children with severe mental and motor disorders solved no task, the findings suggest that the children with psychomotor handicaps may gain the concept of object permanence and that psychomotor treatment may assist them in the development of the concept. This performance is not age-dependent. So the acquisition of the concept of object permanence may be considered an accurate and sensitive tool for the follow-up of the sensorimotor development in the handicapped children.

Permanent magnets and its production by powder metallurgy

Directory of Open Access Journals (Sweden)

Enrique Herraiz Lalana

2018-06-01

Full Text Available In this work, the historical relationship between permanent magnets and powder metallurgy is reviewed. Powder metallurgy is a manufacturing technique based on the compaction of powders that are sintered to create a solid product. This technique was used in the production of permanent magnets for the first time in the 18th century and, nowadays, most permanent magnetic materials are manufacturing by this mean. Magnetic properties are highly dependent on the microstructure of the final product, the magnetic alignment of domains and presence of porosity, to mention a few, and powder metallurgy enables fine control of these factors.

Higher safety and saving of filter material with multi-way sorption filters

International Nuclear Information System (INIS)

Ohlmeyer, M.; Benzel, M.

1978-01-01

The multi-way filter 'Nuclear Karlsruhe' satisfies the requirements of operational safety, high utilisation of the filter material and low pressure drop. An important factor contributing to increased operational safety is due to the fact that the nearly total utilisation of the filter material eliminates the need for optimisation weighing costs against safety. The reduction in filter material consumption reduces not only the direct procurement costs but also the costs of nuclear plants, is radioactive. This contributes in several respects towards a better protection of the environment. The MWS filter can also be used, and presents the same advantages, in non-nuclear plants. (orig.) [de

Topology optimization for design of segmented permanent magnet arrays with ferromagnetic materials

Science.gov (United States)

Lee, Jaewook; Yoon, Minho; Nomura, Tsuyoshi; Dede, Ercan M.

2018-03-01

This paper presents multi-material topology optimization for the co-design of permanent magnet segments and iron material. Specifically, a co-design methodology is proposed to find an optimal border of permanent magnet segments, a pattern of magnetization directions, and an iron shape. A material interpolation scheme is proposed for material property representation among air, permanent magnet, and iron materials. In this scheme, the permanent magnet strength and permeability are controlled by density design variables, and permanent magnet magnetization directions are controlled by angle design variables. In addition, a scheme to penalize intermediate magnetization direction is proposed to achieve segmented permanent magnet arrays with discrete magnetization directions. In this scheme, permanent magnet strength is controlled depending on magnetization direction, and consequently the final permanent magnet design converges into permanent magnet segments having target discrete directions. To validate the effectiveness of the proposed approach, three design examples are provided. The examples include the design of a dipole Halbach cylinder, magnetic system with arbitrarily-shaped cavity, and multi-objective problem resembling a magnetic refrigeration device.

Development of an intense negative hydrogen ion source with a wide-range of external magnetic filter field

International Nuclear Information System (INIS)

Takeiri, Y.; Ando, A.; Kaneko, O.

1994-09-01

An intense negative hydrogen ion source has been developed, which has a strong external magnetic filter field in the wide area of 35 cm x 62 cm produced by a pair of permanent magnet rows located with 35.4 cm separation. The filter strength is 70 G in the center and the line-integrated filter strength is 850 G cm, which keeps the low electron temperature in the extraction region. Strong cusp magnetic field, 1.8 kG on the chamber surface, is generated for improvement of the plasma confinement. These resulted in the high arc efficiency at the low operational gas pressure. A 16.2 A of the H - ion current with the energy of 47 keV was obtained at the arc efficiency of 0.1 A/kW at the gas pressure of 3.8 mTorr in the cesium-mode operation. The magnetic field in the extraction gap is also strong, 450 G, for the electron suppression. The ratio of the extraction to the negative ion currents was less than 2.2 at the gas pressure of 3 mTorr. The two-stage acceleration was tried, and a 13.6 A of the H - ion beam was accelerated to 125 keV. (author)

Crustal deformations at permanent GPS sites in Denmark

DEFF Research Database (Denmark)

Khan, Shfaqat Abbas; Knudsen, Per; Tscherning, Carl Christian

2005-01-01

The National Survey and Cadastre (KMS) is responsible for the geodetic definition of the reference network in Denmark. Permanent GPS stations play an important role in the monitoring and maintenance of the geodetic network. During 1998 and 1999 KMS established three permanent GPS station in Denma...

Combination of Wiener filtering and singular value decomposition filtering for volume imaging PET

International Nuclear Information System (INIS)

Shao, L.; Lewitt, R.M.; Karp, J.S.

1995-01-01

Although the three-dimensional (3D) multi-slice rebinning (MSRB) algorithm in PET is fast and practical, and provides an accurate reconstruction, the MSRB image, in general, suffers from the noise amplified by its singular value decomposition (SVD) filtering operation in the axial direction. Their aim in this study is to combine the use of the Wiener filter (WF) with the SVD to decrease the noise and improve the image quality. The SVD filtering ''deconvolves'' the spatially variant axial response function while the WF suppresses the noise and reduces the blurring not modeled by the axial SVD filter but included in the system modulation transfer function. Therefore, the synthesis of these two techniques combines the advantages of both filters. The authors applied this approach to the volume imaging HEAD PENN-PET brain scanner with an axial extent of 256 mm. This combined filter was evaluated in terms of spatial resolution, image contrast, and signal-to-noise ratio with several phantoms, such as a cold sphere phantom and 3D brain phantom. Specifically, the authors studied both the SVD filter with an axial Wiener filter and the SVD filter with a 3D Wiener filter, and compared the filtered images to those from the 3D reprojection (3DRP) reconstruction algorithm. Their results indicate that the Wiener filter increases the signal-to-noise ratio and also improves the contrast. For the MSRB images of the 3D brain phantom, after 3D WF, both the Gray/White and Gray/Ventricle ratios were improved from 1.8 to 2.8 and 2.1 to 4.1, respectively. In addition, the image quality with the MSRB algorithm is close to that of the 3DRP algorithm with 3D WF applied to both image reconstructions

Comparing superconducting and permanent magnets for magnetic refrigeration

DEFF Research Database (Denmark)

Bjørk, Rasmus; Nielsen, Kaspar Kirstein; Bahl, C. R. H.

2016-01-01

We compare the cost of a high temperature superconducting (SC) tape-based solenoidwith a permanent magnet (PM) Halbach cylinder for magnetic refrigeration.Assuming a five liter active magnetic regenerator volume, the price of each type ofmagnet is determined as a function of aspect ratio...... of the regenerator and desiredinternal magnetic field. It is shown that to produce a 1 T internal field in theregenerator a permanent magnet of hundreds of kilograms is needed or an area ofsuperconducting tape of tens of square meters. The cost of cooling the SC solenoidis shown to be a small fraction of the cost...... of the SC tape. Assuming a cost ofthe SC tape of 6000 $/m2 and a price of the permanent magnet of 100 $/kg, thesuperconducting solenoid is shown to be a factor of 0.3-3 times more expensive thanthe permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspectratio of the regenerator...

Choosing and using astronomical filters

CERN Document Server

Griffiths, Martin

2014-01-01

As a casual read through any of the major amateur astronomical magazines will demonstrate, there are filters available for all aspects of optical astronomy. This book provides a ready resource on the use of the following filters, among others, for observational astronomy or for imaging: Light pollution filters Planetary filters Solar filters Neutral density filters for Moon observation Deep-sky filters, for such objects as galaxies, nebulae and more Deep-sky objects can be imaged in much greater detail than was possible many years ago. Amateur astronomers can take

Magnetic guns with cylindrical permanent magnets

DEFF Research Database (Denmark)

Vokoun, David; Beleggia, Marco; Heller, Luděk

2012-01-01

The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...... of the magnetostatic interaction energy. For comparison, the forces involved are also calculated numerically using finite elements methods. Based on the conservation of the magnetostatic and kinetic energies, the exit and asymptotic velocities are determined. The derived formulas can be used to optimize the generated...... forces and motion of the inner cylindrical magnet....

Design of permanent magnet synchronous motor within minimum cost

OpenAIRE

Півняк, Геннадій Григорович; Бешта, Олександр Степанович; Фурса, Сергій Григорійович; Neuberger, Nikolaus; Nolle, N.

2010-01-01

The article describes design and simulation experience of permanent magnet synchronous motor (PMSM). The design goal is to develop PMSM of the least possible cost. For that purpose the standard induction motor stator was applied as a basic solution and permanent magnets were installed in rotor. Simulation results are presented, the dependence of efficiency and total loss on magnet material mass are obtained. The optimal value of permanent magnets is estimated for the given electric motor frame.

Robust Ensemble Filtering and Its Relation to Covariance Inflation in the Ensemble Kalman Filter

KAUST Repository

Luo, Xiaodong

2011-12-01

A robust ensemble filtering scheme based on the H∞ filtering theory is proposed. The optimal H∞ filter is derived by minimizing the supremum (or maximum) of a predefined cost function, a criterion different from the minimum variance used in the Kalman filter. By design, the H∞ filter is more robust than the Kalman filter, in the sense that the estimation error in the H∞ filter in general has a finite growth rate with respect to the uncertainties in assimilation, except for a special case that corresponds to the Kalman filter. The original form of the H∞ filter contains global constraints in time, which may be inconvenient for sequential data assimilation problems. Therefore a variant is introduced that solves some time-local constraints instead, and hence it is called the time-local H∞ filter (TLHF). By analogy to the ensemble Kalman filter (EnKF), the concept of ensemble time-local H∞ filter (EnTLHF) is also proposed. The general form of the EnTLHF is outlined, and some of its special cases are discussed. In particular, it is shown that an EnKF with certain covariance inflation is essentially an EnTLHF. In this sense, the EnTLHF provides a general framework for conducting covariance inflation in the EnKF-based methods. Some numerical examples are used to assess the relative robustness of the TLHF–EnTLHF in comparison with the corresponding KF–EnKF method.

OPTIMIZATION OF ADVANCED FILTER SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

R.A. Newby; G.J. Bruck; M.A. Alvin; T.E. Lippert

1998-04-30

Reliable, maintainable and cost effective hot gas particulate filter technology is critical to the successful commercialization of advanced, coal-fired power generation technologies, such as IGCC and PFBC. In pilot plant testing, the operating reliability of hot gas particulate filters have been periodically compromised by process issues, such as process upsets and difficult ash cake behavior (ash bridging and sintering), and by design issues, such as cantilevered filter elements damaged by ash bridging, or excessively close packing of filtering surfaces resulting in unacceptable pressure drop or filtering surface plugging. This test experience has focused the issues and has helped to define advanced hot gas filter design concepts that offer higher reliability. Westinghouse has identified two advanced ceramic barrier filter concepts that are configured to minimize the possibility of ash bridge formation and to be robust against ash bridges should they occur. The ''inverted candle filter system'' uses arrays of thin-walled, ceramic candle-type filter elements with inside-surface filtering, and contains the filter elements in metal enclosures for complete separation from ash bridges. The ''sheet filter system'' uses ceramic, flat plate filter elements supported from vertical pipe-header arrays that provide geometry that avoids the buildup of ash bridges and allows free fall of the back-pulse released filter cake. The Optimization of Advanced Filter Systems program is being conducted to evaluate these two advanced designs and to ultimately demonstrate one of the concepts in pilot scale. In the Base Contract program, the subject of this report, Westinghouse has developed conceptual designs of the two advanced ceramic barrier filter systems to assess their performance, availability and cost potential, and to identify technical issues that may hinder the commercialization of the technologies. A plan for the Option I, bench

Generalised Filtering

Directory of Open Access Journals (Sweden)

Karl Friston

2010-01-01

Full Text Available We describe a Bayesian filtering scheme for nonlinear state-space models in continuous time. This scheme is called Generalised Filtering and furnishes posterior (conditional densities on hidden states and unknown parameters generating observed data. Crucially, the scheme operates online, assimilating data to optimize the conditional density on time-varying states and time-invariant parameters. In contrast to Kalman and Particle smoothing, Generalised Filtering does not require a backwards pass. In contrast to variational schemes, it does not assume conditional independence between the states and parameters. Generalised Filtering optimises the conditional density with respect to a free-energy bound on the model's log-evidence. This optimisation uses the generalised motion of hidden states and parameters, under the prior assumption that the motion of the parameters is small. We describe the scheme, present comparative evaluations with a fixed-form variational version, and conclude with an illustrative application to a nonlinear state-space model of brain imaging time-series.

The M/G/1 queue with permanent customers

NARCIS (Netherlands)

Boxma, O.J.; Cohen, J.W.

1991-01-01

The authors examine an M/G/1 FCFS (first come, first served) queue with two types of customers: ordinary customers, who arrive according to a Poisson process, and permanent customers, who immediately return to the end of the queue after having received a service. The influence of the permanent

Sub-micron filter

Science.gov (United States)

Tepper, Frederick [Sanford, FL; Kaledin, Leonid [Port Orange, FL

2009-10-13

Aluminum hydroxide fibers approximately 2 nanometers in diameter and with surface areas ranging from 200 to 650 m.sup.2/g have been found to be highly electropositive. When dispersed in water they are able to attach to and retain electronegative particles. When combined into a composite filter with other fibers or particles they can filter bacteria and nano size particulates such as viruses and colloidal particles at high flux through the filter. Such filters can be used for purification and sterilization of water, biological, medical and pharmaceutical fluids, and as a collector/concentrator for detection and assay of microbes and viruses. The alumina fibers are also capable of filtering sub-micron inorganic and metallic particles to produce ultra pure water. The fibers are suitable as a substrate for growth of cells. Macromolecules such as proteins may be separated from each other based on their electronegative charges.

Sensorless control of ship propulsion interior permanent magnet synchronous motor based on a new sliding mode observer.

Science.gov (United States)

Ren, Jun-Jie; Liu, Yan-Cheng; Wang, Ning; Liu, Si-Yuan

2015-01-01

This paper proposes a sensorless speed control strategy for ship propulsion interior permanent magnet synchronous motor (IPMSM) based on a new sliding-mode observer (SMO). In the SMO the low-pass filter and the method of arc-tangent calculation of extended electromotive force (EMF) or phase-locked loop (PLL) technique are not used. The calculation of the rotor speed is deduced from the Lyapunov function stability analysis. In order to reduce system chattering, sigmoid functions with switching gains being adaptively updated by fuzzy logic systems are innovatively incorporated into the SMO. Finally, simulation results for a 4.088 MW ship propulsion IPMSM and experimental results from a 7.5 kW IPMSM drive are provided to verify the effectiveness of the proposed SMO method. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Recirculating electric air filter

Science.gov (United States)

Bergman, W.

1985-01-09

An electric air filter cartridge has a cylindrical inner high voltage electrode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

Kaon Filtering For CLAS Data

International Nuclear Information System (INIS)

McNabb, J.

2001-01-01

The analysis of data from CLAS is a multi-step process. After the detectors for a given running period have been calibrated, the data is processed in the so called pass-1 cooking. During the pass-1 cooking each event is reconstructed by the program a1c which finds particle tracks and computes momenta from the raw data. The results are then passed on to several data monitoring and filtering utilities. In CLAS software, a filter is a parameterless function which returns an integer indicating whether an event should be kept by that filter or not. There is a main filter program called g1-filter which controls several specific filters and outputs several files, one for each filter. These files may then be analyzed separately, allowing individuals interested in one reaction channel to work from smaller files than using the whole data set would require. There are several constraints on what the filter functions should do. Obviously, the filtered files should be as small as possible, however the filter should also not reject any events that might be used in the later analysis for which the filter was intended

Three-dimensional quadrupole lenses made with permanent magnets

International Nuclear Information System (INIS)

Ivanov, A.S.

1984-01-01

The performance of accelerator systems with quadrupole magnets can be improved by using permanent magnets in quadrupole lenses. This requires better methods for treating the three-dimensional nature of the magnetic fields and the nonlinear characteristics of the magnets. A numerical method is described for simulating three-dimensional magnetic fields and used to analyze quadrupole lenses and doublets with permanent magnets. The results, which are confirmed experimentally, indicate that both the quadrupole magnetic gradient and the effective field length are changed in permanent-magnet quadrupole lenses when the pole lengths and the gap between the lenses are varied while the other characteristics of the magnets remain unchanged

Nonlinear Dynamic Surface Control of Chaos in Permanent Magnet Synchronous Motor Based on the Minimum Weights of RBF Neural Network

Directory of Open Access Journals (Sweden)

Shaohua Luo

2014-01-01

Full Text Available This paper is concerned with the problem of the nonlinear dynamic surface control (DSC of chaos based on the minimum weights of RBF neural network for the permanent magnet synchronous motor system (PMSM wherein the unknown parameters, disturbances, and chaos are presented. RBF neural network is used to approximate the nonlinearities and an adaptive law is employed to estimate unknown parameters. Then, a simple and effective controller is designed by introducing dynamic surface control technique on the basis of first-order filters. Asymptotically tracking stability in the sense of uniformly ultimate boundedness is achieved in a short time. Finally, the performance of the proposed controller is testified through simulation results.

From Microwave Filter to Digital Filter and Back Again

DEFF Research Database (Denmark)

Dalby, Arne Brejning

1989-01-01

A new very simple state variable flow graph representation for interdigital transmission line bandpass filters is presented, which has led to two important results: 1) A new type of digital filter with properties, that surpass the properties of most other (all pole) digital filtertypes. 2) The st...

Model reference adaptive control (MRAC)-based parameter identification applied to surface-mounted permanent magnet synchronous motor

Science.gov (United States)

Zhong, Chongquan; Lin, Yaoyao

2017-11-01

In this work, a model reference adaptive control-based estimated algorithm is proposed for online multi-parameter identification of surface-mounted permanent magnet synchronous machines. By taking the dq-axis equations of a practical motor as the reference model and the dq-axis estimation equations as the adjustable model, a standard model-reference-adaptive-system-based estimator was established. Additionally, the Popov hyperstability principle was used in the design of the adaptive law to guarantee accurate convergence. In order to reduce the oscillation of identification result, this work introduces a first-order low-pass digital filter to improve precision regarding the parameter estimation. The proposed scheme was then applied to an SPM synchronous motor control system without any additional circuits and implemented using a DSP TMS320LF2812. For analysis, the experimental results reveal the effectiveness of the proposed method.

Filter apparatus

International Nuclear Information System (INIS)

Butterworth, D.J.

1980-01-01

This invention relates to liquid filters, precoated by replaceable powders, which are used in the production of ultra pure water required for steam generation of electricity. The filter elements are capable of being installed and removed by remote control so that they can be used in nuclear power reactors. (UK)

Filtering and prediction

CERN Document Server

Fristedt, B; Krylov, N

2007-01-01

Filtering and prediction is about observing moving objects when the observations are corrupted by random errors. The main focus is then on filtering out the errors and extracting from the observations the most precise information about the object, which itself may or may not be moving in a somewhat random fashion. Next comes the prediction step where, using information about the past behavior of the object, one tries to predict its future path. The first three chapters of the book deal with discrete probability spaces, random variables, conditioning, Markov chains, and filtering of discrete Markov chains. The next three chapters deal with the more sophisticated notions of conditioning in nondiscrete situations, filtering of continuous-space Markov chains, and of Wiener process. Filtering and prediction of stationary sequences is discussed in the last two chapters. The authors believe that they have succeeded in presenting necessary ideas in an elementary manner without sacrificing the rigor too much. Such rig...

The intractable cigarette 'filter problem'.

Science.gov (United States)

Harris, Bradford

2011-05-01

When lung cancer fears emerged in the 1950s, cigarette companies initiated a shift in cigarette design from unfiltered to filtered cigarettes. Both the ineffectiveness of cigarette filters and the tobacco industry's misleading marketing of the benefits of filtered cigarettes have been well documented. However, during the 1950s and 1960s, American cigarette companies spent millions of dollars to solve what the industry identified as the 'filter problem'. These extensive filter research and development efforts suggest a phase of genuine optimism among cigarette designers that cigarette filters could be engineered to mitigate the health hazards of smoking. This paper explores the early history of cigarette filter research and development in order to elucidate why and when seemingly sincere filter engineering efforts devolved into manipulations in cigarette design to sustain cigarette marketing and mitigate consumers' concerns about the health consequences of smoking. Relevant word and phrase searches were conducted in the Legacy Tobacco Documents Library online database, Google Patents, and media and medical databases including ProQuest, JSTOR, Medline and PubMed. 13 tobacco industry documents were identified that track prominent developments involved in what the industry referred to as the 'filter problem'. These reveal a period of intense focus on the 'filter problem' that persisted from the mid-1950s to the mid-1960s, featuring collaborations between cigarette producers and large American chemical and textile companies to develop effective filters. In addition, the documents reveal how cigarette filter researchers' growing scientific knowledge of smoke chemistry led to increasing recognition that filters were unlikely to offer significant health protection. One of the primary concerns of cigarette producers was to design cigarette filters that could be economically incorporated into the massive scale of cigarette production. The synthetic plastic cellulose acetate

Bowtie filters for dedicated breast CT: Analysis of bowtie filter material selection

Energy Technology Data Exchange (ETDEWEB)

Kontson, Kimberly, E-mail: Kimberly.Kontson@fda.hhs.gov; Jennings, Robert J. [Department of Bioengineering, University of Maryland, College Park, Maryland 20742 and Division of Imaging and Applied Mathematics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993 (United States)

2015-09-15

Purpose: For a given bowtie filter design, both the selection of material and the physical design control the energy fluence, and consequently the dose distribution, in the object. Using three previously described bowtie filter designs, the goal of this work is to demonstrate the effect that different materials have on the bowtie filter performance measures. Methods: Three bowtie filter designs that compensate for one or more aspects of the beam-modifying effects due to the differences in path length in a projection have been designed. The nature of the designs allows for their realization using a variety of materials. The designs were based on a phantom, 14 cm in diameter, composed of 40% fibroglandular and 60% adipose tissue. Bowtie design #1 is based on single material spectral matching and produces nearly uniform spectral shape for radiation incident upon the detector. Bowtie design #2 uses the idea of basis-material decomposition to produce the same spectral shape and intensity at the detector, using two different materials. With bowtie design #3, it is possible to eliminate the beam hardening effect in the reconstructed image by adjusting the bowtie filter thickness so that the effective attenuation coefficient for every ray is the same. Seven different materials were chosen to represent a range of chemical compositions and densities. After calculation of construction parameters for each bowtie filter design, a bowtie filter was created using each of these materials (assuming reasonable construction parameters were obtained), resulting in a total of 26 bowtie filters modeled analytically and in the PENELOPE Monte Carlo simulation environment. Using the analytical model of each bowtie filter, design profiles were obtained and energy fluence as a function of fan-angle was calculated. Projection images with and without each bowtie filter design were also generated using PENELOPE and reconstructed using FBP. Parameters such as dose distribution, noise uniformity

Bowtie filters for dedicated breast CT: Analysis of bowtie filter material selection

International Nuclear Information System (INIS)

Kontson, Kimberly; Jennings, Robert J.