Percutaneous external fixator pins with bactericidal micron-thin sol-gel films for the prevention of pin tract infection.

PubMed

Qu, Haibo; Knabe, Christine; Radin, Shula; Garino, Jonathan; Ducheyne, Paul

2015-09-01

Risk of infection is considerable in open fractures, especially when fracture fixation devices are used to stabilize the fractured bones. Overall deep infection rates of 16.2% have been reported. The infection rate is even greater, up to 32.2%, with external fixation of femoral fractures. The use of percutaneous implants for certain clinical applications, such as percutaneous implants for external fracture fixation, still represents a challenge today. Currently, bone infections are very difficult to treat. Very potent antibiotics are needed, which creates the risk of irreversible damage to other organs, when the antibiotics are administered systemically. As such, controlled, local release is being pursued, but no such treatments are in clinical use. Herein, the use of bactericidal micron-thin sol-gel films on metallic fracture fixation pins is reported. The data demonstrates that triclosan (2,4,4'-trichloro-2'-hydroxydiphenylether), an antimicrobial agent, can be successfully incorporated into micron-thin sol-gel films deposited on percutaneous pins. The sol-gel films continuously release triclosan in vitro for durations exceeding 8 weeks (longest measured time point). The bactericidal effect of the micron-thin sol-gel films follows from both in vitro and in vivo studies. Inserting percutaneous pins in distal rabbit tibiae, there were no signs of infection around implants coated with a micron-thin sol-gel/triclosan film. Healing had progressed normally, bone tissue growth was normal and there was no epithelial downgrowth. This result was in contrast with the results in rabbits that received control, uncoated percutaneous pins, in which abundant signs of infection and epithelial downgrowth were observed. Thus, well-adherent, micron-thin sol-gel films laden with a bactericidal molecule successfully prevented pin tract infection. Copyright © 2015 Elsevier Ltd. All rights reserved.

[epiDRB--a new minimally invasive concept for referencing in the field of computer-assisted orthopaedic surgery].

PubMed

Ohnsorge, J A K; Weisskopf, M; Siebert, C H

2005-01-01

Optoelectronic navigation for computer-assisted orthopaedic surgery (CAOS) is based on a firm connection of bone with passive reflectors or active light-emitting diodes in a specific three-dimensional pattern. Even a so-called "minimally-invasive" dynamic reference base (DRB) requires fixation with screws or clamps via incision of the skin. Consequently an originally percutaneous intervention would unnecessarily be extended to an open procedure. Thus, computer-assisted navigation is rarely applied. Due to their tree-like design most DRB's interfere with the surgeon's actions and therefore are at permanent risk to be accidentally dislocated. Accordingly, the optic communication between the camera and the operative site may repeatedly be interrupted. The aim of the research was the development of a less bulky, more comfortable, stable and safely trackable device that can be fixed truly percutaneously. With engineering support of the industrial partner the radiolucent epiDRB was developed. It can be fixed with two or more pins and gains additional stability from its epicutaneous position. The intraoperative applicability and reliability was experimentally tested. Its low centre of gravity and its flat design allow the device to be located directly in the area of interest. Thanks to its epicutaneous position and its particular shape the epiDRB may perpetually be tracked by the navigation system without hindering the surgeon's actions. Hence, the risk of being displaced by accident is minimised and the line of sight remains unaffected. With the newly developed epiDRB computer-assisted navigation becomes easier and safer to handle even in punctures and other percutaneous procedures at the spine as much as at the extremities without an unproportionate amount of additional trauma. Due to the special design referencing of more than one vertebral body is possible at one time, thus decreasing radiation exposure and increasing efficiency.

Temporary Percutaneous Pedicle Screw Stabilization Without Fusion of Adolescent Thoracolumbar Spine Fractures.

PubMed

Cui, Shari; Busel, Gennadiy A; Puryear, Aki S

2016-01-01

Pediatric spine trauma often results from high-energy mechanisms. Despite differences in healing potential, comorbidities, and length of remaining life, treatment is frequently based on adult criteria; ligamentous injuries are fused and bony injuries are treated accordingly. In this study, we present short-term results of a select group of adolescent patients treated using percutaneous pedicle screw instrumentation without fusion. An IRB-approved retrospective review was performed at a level 1 pediatric trauma center for thoracolumbar spine fractures treated by percutaneous pedicle screw instrumentation. Patients were excluded if arthrodesis was performed or if instrumentation was not removed. Demographics, injury mechanism, associated injuries, fracture classification, surgical data, radiographic measures, and complications were collected. Radiographs were analyzed for sagittal and coronal wedge angles and vertebral body height ratio and statistical comparisons performed on preoperative and postoperative values. Between 2005 and 2013, 46 patients were treated surgically. Fourteen patients (5 male, 9 female) met inclusion criteria. Injury mechanisms included 8 motor vehicle collisions, 4 falls, and 2 all-terrain vehicle/motorcycle collisions. There were 8 Magerl type A injuries, 4 type B injuries, and 2 type C injuries. There was 1 incomplete spinal cord injury. Implants were removed between 5 and 12 months in 12 patients and after 12 months in 2 patients. Statistical analysis revealed significant postoperative improvement in all radiographic measures (P<0.05). There were no neurological complications, 1 superficial wound dehiscence, and 2 instrumentation failures (treated with standard removal). At last follow-up, 11 patients returned to unrestricted activities including sports. Average follow-up was 9 months after implant removal and 19.3 months after index procedure. Adolescent thoracolumbar fractures present unique challenges and treatment opportunities different from the adult patient. We present a nonconsecutive series of 14 patients temporarily stabilized with percutaneous pedicle screw fixation for injuries including 3-column fracture dislocations and purely ligamentous injuries. Temporary fusionless instrumentation can provide successful management of select thoracolumbar spine injuries in pediatric trauma patients. Level IV-Retrospective case series.

Formulation and evaluation of lidocaine base ethosomes for transdermal delivery.

PubMed

Zhu, Xiaoliang; Li, Fuli; Peng, Xuebiao; Zeng, Kang

2013-08-01

Although transdermal preparations of local anesthetics have been used to reduce pain caused by skin surgery, these preparations cannot effectively penetrate through the epidermis because of the barrier formed by the stratum corneum and the thick epidermis. Ethosomes can effectively transport drugs across the skin because of their thermodynamic stability, small size, high encapsulation efficiency, and percutaneous penetration. We evaluated lidocaine base ethosomes by measuring their loading efficiency, encapsulation efficiency, thermodynamic stability, and percutaneous penetration capability in vitro, and their effectiveness and cutaneous irritation in vivo. Lidocaine base ethosomes were prepared using the injection-sonication-filter method. Size, loading efficiency, encapsulation efficiency, and stability were evaluated using a Zetasizer and high performance liquid chromatography. Formulation was determined by measuring the maximum encapsulation efficiency in the orthogonal test. Percutaneous penetration efficiency in vitro was analyzed using a Franz-type diffusion cell experiment. In vivo effectiveness was analyzed using the pinprick test. Cutaneous irritancy tests were performed on white guinea pigs, followed by histopathologic analysis. The results were compared with lidocaine liposomes as well as lidocaine delivered in a hydroethanolic solution. Lidocaine base ethosomes composed of 5% (w/w) egg phosphatidyl choline, 35% (w/w) ethanol, 0.2% (w/w) cholesterol, 5% (w/w) lidocaine base, and ultrapure water had a mean maximum encapsulation of 51% ± 4%, a mean particle size of 31 ± 3 nm, and a mean loading efficiency of 95.0% ± 0.1%. The encapsulation efficiency of lidocaine base ethosomes remained stable for 60 days at 25°C ± 1°C (95% confidence interval [CI], -1.12% to 1.34%; P = 0.833). The transdermal flux of lidocaine base differed significantly for the 3 preparations (F = 120, P < 0.001), being significantly greater from ethosomes than from liposomes (95% corrected CI, 1129-1818 µg/(cm(2)·h); P < 0.001), and from hydroethanolic solution (95% corrected CI, 1468-2157 µg/(cm(2)·h); P < 0.001). Lidocaine base ethosomes had a shorter onset time and longer duration in vivo than did lidocaine base liposomes or lidocaine delivered in a hydroethanolic solution. Lidocaine base ethosomes showed no evidence of dermal irritation in guinea pigs. Ethosomes are potential carriers of local anesthetics across the skin and may have applicability for other percutaneous drugs that require rapid onset.

Percutaneous Method of Management of Simple Bone Cyst

PubMed Central

Lakhwani, O. P.

2013-01-01

Introduction. Simple bone cyst or unicameral bone cysts are benign osteolytic lesions seen in metadiaphysis of long bones in growing children. Various treatment modalities with variable outcomes have been described in the literature. The case report illustrates the surgical technique of minimally invasive method of treatment. Case Study. A 14-year-old boy was diagnosed as active simple bone cyst proximal humerus with pathological fracture. The patient was treated by minimally invasive percutaneous curettage with titanium elastic nail (TENS) and allogenic bone grafting mixed with bone marrow under image intensifier guidance. Results. Pathological fracture was healed and allograft filled in the cavity was well taken up. The patient achieved full range of motion with successful outcome. Conclusion. Minimally invasive percutaneous method using elastic intramedullary nail gives benefit of curettage cyst decompression and stabilization of fracture. Allogenic bone graft fills the cavity and healing of lesion by osteointegration. This method may be considered with advantage of minimally invasive technique in treatment of benign cystic lesions of bone, and the level of evidence was therapeutic level V. PMID:23819089

Tibial plafond fractures: limited incision reduction with percutaneous fixation.

PubMed

Salton, Heather L; Rush, Shannon; Schuberth, John

2007-01-01

This study was a retrospective review of 18 patients with 19 pilon fractures treated with limited incision reduction and percutaneous plate fixation of the tibia. Patients were treated with either a 1- or 2-stage protocol. The latter consisted of placement of an external fixator followed by definitive reduction. The emphasis of analysis was placed on the identification of complications to the soft tissue envelope or bone-healing problems within the first 6 months after surgery. A major complication was defined as an unplanned operation within the first 6 months. Minor complications were any superficial wound defects that did not require operative intervention to resolve or any malunion or delayed union. With this protocol, no major complications were encountered. Minor complications were identified in 4 patients (4 fractures) of which 2 were minor wound problems. One patient developed a malunion, and the other had a delayed union. Four patients requested removal of prominent hardware. These results indicate that limited incision reduction and percutaneous plate fixation lead to safe methods of stabilization. The authors also provide guidance and strategies for the consistent execution of this technique.

Biomechanical study of four kinds of percutaneous screw fixation in two types of unilateral sacroiliac joint dislocation: a finite element analysis.

PubMed

Zhang, Lihai; Peng, Ye; Du, Chengfei; Tang, Peifu

2014-12-01

To compare the biomechanical stability of four different kinds of percutaneous screw fixation in two types of unilateral sacroiliac joint dislocation. Finite element models of unstable Tile type B and type C pelvic ring injuries were created in this study. Modelling was based on fixation with a single S1 screw (S1-1), single S2 screw (S2-1), two S1 screws (S1-2) and a combination of a single S1 and a single S2 screw (S1–S2). The biomechanical test of two types of pelvic instability (rotational or vertical) with four types of percutaneous fixation were compared. Displacement, flexion and lateral bend (in bilateral stance) were recorded and analyzed. Maximal inferior translation (displacement) was found in the S2-1 group in type B and C dislocations which were 1.58 mm and 1.90 mm, respectively. Maximal flexion was found in the S2-1 group in type B and C dislocations which were 1.55° and 1.95°, respectively. The results show that the flexion from most significant angulation to least is S2-1, S1-1, S1-2, and S1–S2 in type B and C dislocations. All the fixations have minimal lateral bend. Our findings suggest single screw S1 fixation should be adequate fixation for a type B dislocation. For type C dislocations, one might consider a two screw construct (S1–S2) to give added biomechanical stability if clinically indicated.

Combined Volar Hamate Dislocation and Scapholunate Ligament Rupture: A Case Report.

PubMed

Walmsley, David; Dhotar, Herman; Geddes, Christopher; Axelrod, Terry

2015-04-22

A twenty-two-year-old male patient presented to our trauma center after a motor-vehicle accident in which he sustained multiple injuries, including a volar dislocation of the hamate and ipsilateral scapholunate dissociation. Following closed reduction of the hamate dislocation, open reduction and stabilization of these carpal injuries was undertaken two days post-injury via a dorsal approach. Percutaneous Kirschner wires were used as well as two mini suture anchors to repair the scapholunate ligament. The patient was immobilized for six weeks and Kirschner wires were removed at twelve weeks postoperatively. To our knowledge, hamate dislocation with scapholunate dissociation and its surgical treatment have not previously been described. Successful surgical treatment for this injury pattern may be performed dorsally via direct reduction and repair of the scapholunate ligament with percutaneous pinning of the affected carpal bones.

External fixation techniques for distal radius fractures.

PubMed

Capo, John T; Swan, Kenneth G; Tan, Virak

2006-04-01

Fractures of the distal radius are common injuries. Low-energy or high-energy mechanisms may be involved. Unstable distal radius fractures present a challenge to the treating orthopaedic surgeon. External fixation is a valuable instrument for fracture reduction and stabilization. Limited open incisions, early range of motion, and treatment of complex wounds are a few of the benefits of external fixation. Fixators may be spanning or nonbridging and may be used alone or in combination with other stabilization methods to obtain and maintain distal radius fracture reduction. Augmentation with percutaneous wires allows for optimal fracture stabilization with physiologic alignment of the wrist. Moderate distraction at the carpus does not induce postoperative stiffness. The distal radioulnar joint must be assessed and may need to be stabilized. Complications of external fixation are usually minor, but must be anticipated and treated early. Level V (expert opinion).

Performance of advanced trauma life support procedures in microgravity

NASA Technical Reports Server (NTRS)

Campbell, Mark R.; Billica, Roger D.; Johnston, Smith L 3rd; Muller, Matthew S.

2002-01-01

BACKGROUND: Medical operations on the International Space Station will emphasize the stabilization and transport of critically injured personnel and so will need to be capable of advanced trauma life support (ATLS). METHODS: We evaluated the ATLS invasive procedures in the microgravity environment of parabolic flight using a porcine animal model. Included in the procedures evaluated were artificial ventilation, intravenous infusion, laceration closure, tracheostomy, Foley catheter drainage, chest tube insertion, peritoneal lavage, and the use of telemedicine methods for procedural direction. RESULTS: Artificial ventilation was performed and appeared to be unaltered from the 1-G environment. Intravenous infusion, laceration closure, percutaneous dilational tracheostomy, and Foley catheter drainage were achieved without difficulty. Chest tube insertion and drainage were performed with no more difficulty than in the 1-G environment due to the ability to restrain patient, operator and supplies. A Heimlich valve and Sorenson drainage system were both used to provide for chest tube drainage collection with minimal equipment, without the risk of atmospheric contamination, and with the capability to auto-transfuse blood drained from a hemothorax. The use of telemedicine in chest tube insertion was demonstrated to be useful and feasible. Peritoneal lavage using a percutaneous technique, although requiring less training to perform, was found to be dangerous in weightlessness due to the additional pressure of the bowel on the anterior abdominal wall creating a high risk of bowel perforation. CONCLUSIONS: The performance of ATLS procedures in microgravity appears to be feasible with the exception of diagnostic peritoneal lavage. Minor modifications to equipment and techniques are required in microgravity to effect surgical drainage in the presence of altered fluid dynamics, to prevent atmospheric contamination, and to provide for the restraint requirements. A parabolic simulation system was developed for equipment and procedure verification, physiological research, and possible crew medical officer training in the future.

Pelvic ring injuries: Surgical management and long-term outcomes

PubMed Central

Halawi, Mohamad J.

2016-01-01

Pelvic ring injuries present a therapeutic challenge to the orthopedic surgeon. Management is based on the patient's physiological status, fracture classification, and associated injuries. Surgical stabilization is indicated in unstable injury patterns and those that fail nonsurgical management. The optimal timing for definitive fixation is not clearly defined, but early stabilization is recommended. Surgical techniques include external fixation, open reduction and internal fixation, and minimally invasive percutaneous osteosynthesis. Special considerations are required for concomitant acetabular fractures, sacral fractures, and those occurring in skeletally immature patients. Long-term outcomes are limited by lack of pelvis-specific outcome measures and burden of associated injuries. PMID:26908968

Percutaneous Posterior Transarticular Atlantoaxial Fixation for the Treatment of Odontoid Fractures in the Elderly: A Prospective Study.

PubMed

Alhashash, Mohamed; Shousha, Mootaz; Gendy, Hany; Barakat, Ahmed Samir; Boehm, Heinrich

2018-06-01

A prospective study of 20 multimorbid patients older than 65 years undergoing minimally invasive surgical treatment for odontoid fracture. To analyze the results of percutaneous transarticular atlantoaxial screw fixation as a new minimally invasive treatment modality in this high risk group of patients. Odontoid fractures are a common injury pattern in the elderly. These fractures typically present significant challenges as geriatric patients often have multiple comorbidities that may adversely affect fracture management. Despite numerous publications on this subject, with a trend toward primary operative stabilization, the appropriate treatment for this frequent and potentially life threatening injury remains controversial. Between January 2013 and December 2015, 20 consecutive patients underwent posterior percutaneous transarticular atlantoaxial screw fixation for odontoid fracture type II. The two main inclusion criteria were age 65 years or older and ASA score of III or IV. The screws were inserted percutaneously with the help of two fluoroscopy devices. Clinical and radiological examinations were regularly performed for a minimum of 18 months postoperatively. The mean age was 81 years, all of them with multiple comorbidities. Reduction of the fracture and screw insertion was possible in all cases. The mean operative time was 51.75 minutes and mean blood loss was 41.7 mL. Three patients died in the first 3 months after surgery. Healing of the fracture occurred in 15 patients (88.2%). Revision surgery was not necessary in any of the patients. Mean visual analogue scale (VAS) at the final follow-up was 2.4, and mean patient satisfaction score was 7.1. Percutaneous transarticular atlantoaxial fixation in elderly patients offers a good minimally invasive operative treatment in this multimorbid group of patients. This new technique with short operative time is well tolerated by the geriatric patients leading to a healing rate up to 88%. 4.

Percutaneous Valvuloplasty for Bioprosthetic Tricuspid Valve Stenosis

PubMed Central

Malhotra, Rohit; Sharma, Anjali; Kakouros, Nikolaos

2017-01-01

Percutaneous transcatheter tricuspid balloon valvuloplasty (PTTBV) is an accepted treatment option for symptomatic severe native tricuspid valve stenosis, although surgical tricuspid valve replacement remains the treatment of choice. There have been few reports of successful PTTBV for bioprosthetic tricuspid valve stenosis. We present case reports of 3 patients from our hospital experience. Two of the 3 cases were successful, with lasting clinical improvement, whereas the 3rd patient failed to show a reduction in valve gradient. We describe the standard technique used for PTTBV. We present results from a literature review that identified 16 previously reported cases of PTTBV for bioprosthetic severe tricuspid stenosis, with overall favorable results. We conclude that PTTBV should perhaps be considered for a select patient population in which symptomatic improvement and hemodynamic stability are desired immediately, and particularly for patients who are inoperable or at high surgical risk. PMID:28265212

Percutaneous Ventricular Assist Devices: A Health Technology Assessment.

PubMed

2017-01-01

Percutaneous coronary intervention (PCI)-using a catheter to place a stent to keep blood vessels open-is increasingly used for high-risk patients who cannot undergo surgery. Cardiogenic shock (when the heart suddenly cannot pump enough blood) is associated with a high mortality rate. The percutaneous ventricular assist device can help control blood pressure and increase blood flow in these high-risk conditions. This health technology assessment examined the benefits, harms, and budget impact of the Impella percutaneous ventricular assist device in high-risk PCI and cardiogenic shock. We also analyzed cost-effectiveness of the Impella device in high-risk PCI. We performed a systematic search of the literature for studies examining the effects of the Impella percutaneous ventricular assist device in high-risk PCI and cardiogenic shock, and appraised the evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria, focusing on hemodynamic stability, mortality, major adverse cardiac events, bleeding, and vascular complications. We developed a Markov decision-analytical model to assess the cost- effectiveness of Impella devices versus intra-aortic balloon pumps (IABPs), calculated incremental cost-effectiveness ratios (ICERs) using a 10-year time horizon, and conducted sensitivity analyses to examine the robustness of the estimates. The economic model was conducted from the perspective of the Ontario Ministry of Health and Long-Term Care. Eighteen studies (one randomized controlled trial and 10 observational studies for high-risk PCI, and one randomized controlled trial and six observational studies for cardiogenic shock) were included in the clinical review. Compared with IABPs, Impella 2.5, one model of the device, improved hemodynamic parameters (GRADE low-very low) but showed no significant difference in mortality (GRADE low), major adverse cardiac events (GRADE low), bleeding (GRADE low), or vascular complications (GRADE low) in high-risk PCI and cardiogenic shock. No randomized controlled trials or prospective observational studies with a control group have studied Impella CP and Impella 5.0 (other models of the device) in patients undergoing high-risk PCI or patients with cardiogenic shock. The economic model predicted that treatment with the Impella device would have fewer quality-adjusted life-years (QALYs) and higher costs than IABP in high-risk PCI patients. These observations were consistent even when uncertainty in model inputs and parameters was considered. We estimated that adopting Impella would increase costs by $2.9 to $11.5 million per year. On the basis of evidence of low to very low quality, Impella 2.5 devices were associated with improved hemodynamic stability, but had mortality rates and safety profile similar to IABPs in high-risk PCI and cardiogenic shock. Our cost-effectiveness analysis indicated that Impella 2.5 is likely associated with greater costs and fewer quality-adjusted life years than IABP.

Paclitaxel-eluting versus sirolimus-eluting stents in diabetes mellitus: a report from the National Heart, Lung, and Blood Institute Dynamic Registry.

PubMed

Wolf, William M; Vlachos, Helen A; Marroquin, Oscar C; Lee, Joon S; Smith, Conrad; Anderson, William D; Schindler, John T; Holper, Elizabeth M; Abbott, J Dawn; Williams, David O; Laskey, Warren K; Kip, Kevin E; Kelsey, Sheryl F; Mulukutla, Suresh R

2010-02-01

Diabetes is a powerful predictor of adverse events in patients undergoing percutaneous coronary intervention. Drug-eluting stents reduce restenosis rates compared with bare metal stents; however, controversy remains regarding which drug-eluting stents provides greater benefit in patients with diabetes. Accordingly, we compared the safety and efficacy of sirolimus-eluting stents (SES) with paclitaxel-eluting stents (PES) among diabetic patients in a contemporary registry. Using the National Heart, Lung, and Blood Institute Dynamic Registry, we evaluated 2-year outcomes of diabetic patients undergoing percutaneous coronary interventions with SES (n=677) and PES (n=328). Clinical and demographic characteristics, including age, body mass index, insulin use, left ventricular function, and aspirin/clopidogrel use postprocedure, did not differ significantly between the groups except that PES-treated patients had a greater frequency of hypertension and hyperlipidemia. At the 2-year follow-up, no significant differences were observed between PES and SES with regard to safety or efficacy end points. PES- and SES-treated patients had similar rates of death (10.7% versus 8.2%, P=0.20), death and myocardial infarction (14.9% versus 13.6%, P=0.55), repeat revascularization (14.8% versus 17.8%, P=0.36), and stent thrombosis (1.3% versus 1.3%, P=0.95). After adjustment, no significant differences between the 2 stent types in any outcome were observed. PES and SES are equally efficacious and have similar safety profiles in diabetic patients undergoing percutaneous coronary interventions in clinical practice.

Marked improvements in outcomes of contemporary percutaneous coronary intervention in patients with diabetes mellitus.

PubMed

Freeman, Andrew M; Abbott, J Dawn; Jacobs, Alice K; Vlachos, Helen A; Selzer, Faith; Laskey, Warren K; Detre, Katherine M; Williams, David O

2006-12-01

We sought to determine if advances in percutaneous coronary intervention (PCI) are associated with better outcomes among patients with diabetes mellitus (DM). Patients with DM enrolled in the National Heart, Lung, and Blood Institute (NHLBI) early PTCA Registry (1985-1986) were compared to those in the subsequent contemporary Dynamic Registry (1999-2002) for in-hospital and one-year cardiovascular outcomes. The study population included 945 adults with DM, 325 from the PTCA Registry and 620 from the Dynamic Registry. Multivariable Cox regression models were built to estimate the risk of clinical events. Dynamic Registry patients were older, had more noncardiac comorbidities, and a lower mean ejection fraction (50.5% vs 57.8%, P < or = 0.001) compared to the PTCA Registry patients. The incidence of in-hospital mortality (1.9% vs 4.3%, P < or = 0.05), myocardial infarction (MI) (1.0% vs 7.4%, P

Two Different Percutaneous Bone-Anchored Hearing Aid Abutment Systems: Comparative Clinical Study.

PubMed

Polat, Beldan; İşeri, Mete; Orhan, Kadir Serkan; Yılmazer, Ayça Başkadem; Enver, Necati; Ceylan, Didem; Kara, Ahmet; Güldiken, Yahya; Çomoğlu, Şenol

2016-04-01

To compare two different percutaneous bone-anchored hearing aid (BAHA) abutment systems regarding operation time, scar healing, quality of life, implant stability, audiologic results, and complications. The study involves a prospective multi-center clinical evaluation. Thirty-two consecutive patients who had undergone BAHA surgery from January 2011 to January 2013 in two tertiary centers were included in the study. The Glasgow Inventory Benefit Score was used to assess the patients at least 6 months after surgery. The operation time and complications were recorded. Implant stability quotient (ISQ) values were recorded using resonance frequency analysis. Holger's classification was used to evaluate skin reactions. The mean length of the operation was 39.2±4 min for standard abutment and 18.3±5.7 min for hydroxyapatite-coated abutment. ISQ scores were significantly better for standard abutment in all tests. The mean total Glasgow Inventory Benefit Score was 39.3±19 for the standard abutment and 46.3±24.5 for the hydroxyapatite-coated abutment groups, but there was no statistical significance between the two groups. There was no difference in audiological improvement between the two groups after surgery. Hydroxyapatite-coated abutment provided a shorter operation time that was significantly different from standard abutment. There were no significant differences between standard abutment and hydroxyapatite-coated abutment regarding audiologic improvement, quality of life, loading time, and complications.

Mini access guide to simplify calyceal access during percutaneous nephrolithotomy: A novel device.

PubMed

Chowdhury, Puskar Shyam; Nayak, Prasant; David, Deepak; Mallick, Sujata

2017-01-01

A precise puncture of the renal collecting system is the most essential step for percutaneous nephrolithotomy (PCNL). There are many techniques describing this crucial first step in PCNL including the bull's eye technique, triangulation technique, free-hand technique, and gradual descensus technique. We describe a novel puncture guide to assist accurate percutaneous needle placement during bull's eye technique. The mini access guide (MAG) stabilizes the initial puncture needle by mounting it on an adjustable multidirectional carrier fixed to the patient's skin, which aids in achieving the "bull's eye" puncture. It also avoids a direct fluoroscopic exposure of the urologist's hand during the puncture. Sixty consecutive patients with solitary renal calculus were randomized to traditional hand versus MAG puncture during bull's eye technique of puncture and the fluoroscopy time was assessed. The median fluoroscopy screening time for traditional free-hand bull's eye and MAG-guided bull's eye puncture (fluoroscopic screening time for puncture) was 55 versus 21 s ( P = 0.001) and the median time to puncture was 80 versus 55 s ( P = 0.052), respectively. Novice residents also learned puncture technique faster with MAG on simulator. The MAG is a simple, portable, cheap, and novel assistant to achieve successful PCNL puncture. It would be of great help for novices to establish access during their learning phase of PCNL. It would also be an asset toward significantly decreasing the radiation dose during PCNL access.

An improved process for development and testing of vena caval filters: the percutaneous steel Greenfield filter.

PubMed

Greenfield, L J; Proctor, M C; Roberts, K R

1997-01-01

The purpose of this study was to develop a reduced profile stainless steel Greenfield filter with an over-the-wire delivery system and to compare its performance with the existing Food and Drug Administration-approved Greenfield filters. In addition, we wanted to standardize a system for evaluating filter prototypes. Percutaneous stainless steel filters with various hook configurations were evaluated for efficacy and safety in four in vitro modules designed to reproduce potential liabilities experimentally. Animal studies to assess thrombus capture and resolution, filter stability, migration, and hemodynamics were completed in 4 dogs and 38 sheep. Mathematical modeling suggested that hook angle was the most relevant factor in improving resistance to migration. Prototypes that varied with respect to hook length and angle were evaluated in both the in vitro testing unit and in sheep. The stainless steel filter with two downward directed hooks provided clot capture comparable with the current Greenfield filter, maintenance of flow, and resistance to fatigue and corrosion while providing significant resistance to migration and penetration (p < 0.05). The percutaneous stainless steel Greenfield filter with the alternating hook design provides a reduced profile device that can be placed over a wire to improve positioning. The use of a standardized testing system reduced both the time and cost of bringing this new device to the market.

The addition of body armor diminishes dynamic postural stability in military soldiers.

PubMed

Sell, Timothy C; Pederson, Jonathan J; Abt, John P; Nagai, Takashi; Deluzio, Jennifer; Wirt, Michael D; McCord, Larry J; Lephart, Scott M

2013-01-01

Poor postural stability has been identified as a risk factor for lower extremity musculoskeletal injury. The additional weight of body armor carried by Soldiers alters static postural stability and may predispose Soldiers to lower extremity musculoskeletal injuries. However, static postural stability tasks poorly replicate the dynamic military environment, which places considerable stress on the postural control system during tactical training and combat. Therefore, the purpose of this study was to examine the effects of body armor on dynamic postural stability during single-leg jump landings. Thirty-six 101st Airborne Division (Air Assault) Soldiers performed single-leg jump landings in the anterior direction with and without wearing body armor. The dynamic postural stability index and the individual stability indices (medial-lateral stability index, anterior-posterior stability index, and vertical stability index) were calculated for each condition. Paired sample t-tests were performed to determine differences between conditions. Significant differences existed for the medial-lateral stability index, anterior-posterior stability index, vertical stability index, and dynamic postural stability index (p < 0.05). The addition of body armor resulted in diminished dynamic postural stability, which may result in increased lower extremity injuries. Training programs should address the altered dynamic postural stability while wearing body armor in attempts to promote adaptations that will result in safer performance during dynamic tasks.

Aortocoronary dissection with acute left main artery occlusion: successful treatment with emergent stenting.

PubMed

Wykrzykowska, Joanna J; Carrozza, Joseph; Laham, Roger J

2006-08-01

Iatrogenic aortocoronary dissection is a rare but devastating complication of percutaneous coronary interventions and cardiac surgery, with a mortality rate up to 35%. Of the type-A dissections in the International Registry of Aortic Dissections (IRAD), 27% were caused by coronary interventions. The mechanism involves an initial dissection in the coronary artery, which then propagates in a retrograde fashion past the sinuses of Valsalva, often several centimeters beyond the aortic valve. With the advent of complex interventions such as left main stent implantation, revascularization of chronic total occlusions and mechanical thrombectomy, this complication may become more prevalent. Here we present a unique case of percutaneous coronary intervention (PCI) of the left circumflex (LCx) artery complicated by a left main coronary dissection that propagated approximately 8 cm into the ascending aorta and caused abrupt left main coronary artery occlusion and hemodynamic collapse. Rescue of the left main artery and sealing of the aortic dissection with stabilization of the patient was possible with rapid ostial left main artery stenting.

Percutaneous Ventricular Assist Devices: A Health Technology Assessment

PubMed Central

Lee, Christine; Djalalov, Sandjar; Xie, Xuanqian; Holubowich, Corinne

2017-01-01

Background Percutaneous coronary intervention (PCI)—using a catheter to place a stent to keep blood vessels open—is increasingly used for high-risk patients who cannot undergo surgery. Cardiogenic shock (when the heart suddenly cannot pump enough blood) is associated with a high mortality rate. The percutaneous ventricular assist device can help control blood pressure and increase blood flow in these high-risk conditions. This health technology assessment examined the benefits, harms, and budget impact of the Impella percutaneous ventricular assist device in high-risk PCI and cardiogenic shock. We also analyzed cost-effectiveness of the Impella device in high-risk PCI. Methods We performed a systematic search of the literature for studies examining the effects of the Impella percutaneous ventricular assist device in high-risk PCI and cardiogenic shock, and appraised the evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria, focusing on hemodynamic stability, mortality, major adverse cardiac events, bleeding, and vascular complications. We developed a Markov decision-analytical model to assess the cost- effectiveness of Impella devices versus intra-aortic balloon pumps (IABPs), calculated incremental cost-effectiveness ratios (ICERs) using a 10-year time horizon, and conducted sensitivity analyses to examine the robustness of the estimates. The economic model was conducted from the perspective of the Ontario Ministry of Health and Long-Term Care. Results Eighteen studies (one randomized controlled trial and 10 observational studies for high-risk PCI, and one randomized controlled trial and six observational studies for cardiogenic shock) were included in the clinical review. Compared with IABPs, Impella 2.5, one model of the device, improved hemodynamic parameters (GRADE low–very low) but showed no significant difference in mortality (GRADE low), major adverse cardiac events (GRADE low), bleeding (GRADE low), or vascular complications (GRADE low) in high-risk PCI and cardiogenic shock. No randomized controlled trials or prospective observational studies with a control group have studied Impella CP and Impella 5.0 (other models of the device) in patients undergoing high-risk PCI or patients with cardiogenic shock. The economic model predicted that treatment with the Impella device would have fewer quality-adjusted life-years (QALYs) and higher costs than IABP in high-risk PCI patients. These observations were consistent even when uncertainty in model inputs and parameters was considered. We estimated that adopting Impella would increase costs by $2.9 to $11.5 million per year. Conclusions On the basis of evidence of low to very low quality, Impella 2.5 devices were associated with improved hemodynamic stability, but had mortality rates and safety profile similar to IABPs in high-risk PCI and cardiogenic shock. Our cost-effectiveness analysis indicated that Impella 2.5 is likely associated with greater costs and fewer quality-adjusted life years than IABP. PMID:28232854

Effect of Footwear on Dynamic Stability during Single-leg Jump Landings.

PubMed

Bowser, Bradley J; Rose, William C; McGrath, Robert; Salerno, Jilian; Wallace, Joshua; Davis, Irene S

2017-06-01

Barefoot and minimal footwear running has led to greater interest in the biomechanical effects of different types of footwear. The effect of running footwear on dynamic stability is not well understood. The purpose of this study was to compare dynamic stability and impact loading across 3 footwear conditions; barefoot, minimal footwear and standard running shoes. 25 injury free runners (21 male, 4 female) completed 5 single-leg jump landings in each footwear condition. Dynamic stability was assessed using the dynamic postural stability index and its directional components (mediolateral, anteroposterior, vertical). Peak vertical ground reaction force and vertical loadrates were also compared across footwear conditions. Dynamic stability was dependent on footwear type for all stability indices (ANOVA, p<0.05). Post-hoc tests showed dynamic stability was greater when barefoot than in running shoes for each stability index (p<0.02) and greater than minimal footwear for the anteroposterior stability index (p<0.01). Peak vertical force and average loadrates were both dependent on footwear (p≤0.05). Dynamic stability, peak vertical force, and average loadrates during single-leg jump landings appear to be affected by footwear type. The results suggest greater dynamic stability and lower impact loading when landing barefoot or in minimal footwear. © Georg Thieme Verlag KG Stuttgart · New York.

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

Masala, Salvatore; Roselli, Mario; Manenti, Guglielmo

A 70-year-old man with a painful vertebral metastasis was treated with combined percutaneous cryoablation and vertebroplasty therapy (CVT) in one session. The patient was suffering from diffuse visceral metastasized cholangiocarcinoma. After several weeks of back pain, magnetic resonance imaging documented a single L2 bone metastasis. In consultation with the oncologists, palliative combined CVT was administered with the aim of obtaining pain relief and bone stabilization. In our experience this combined treatment is safe and effective for immediate pain relief in painful bone metastases when other standard palliative treatments have failed.

Transcatheter Retrieval of Embolized Atrial Septal Defect Occluder Device by Waist Capture Technique.

PubMed

Her, Ae-Young; Lim, Kyung-Hun; Shin, Eun-Seok

2018-01-27

This case study describes the successful percutaneous transcatheter retrieval of an embolized Amplatzer occluder device using the "waist capture technique" in a patient with an atrial septal defect. This technique allowed for stability of the Amplatzer device, compression of the atrial discs for easier removal, prevention of further embolization, and minimal injury to vasculature during device retrieval. This novel and effective technique can be used safely for the retrieval of Amplatzer devices in the venous system.

Percutaneous window chamber method for chronic intravital microscopy of sensor-tissue interactions.

PubMed

Koschwanez, Heidi E; Klitzman, Bruce; Reichert, W Monty

2008-11-01

A dorsal, two-sided skin-fold window chamber model was employed previously by Gough in glucose sensor research to characterize poorly understood physiological factors affecting sensor performance. We have extended this work by developing a percutaneous one-sided window chamber model for the rodent dorsum that offers both a larger subcutaneous area and a less restrictive tissue space than previous animal models. A surgical procedure for implanting a sensor into the subcutis beneath an acrylic window (15 mm diameter) is presented. Methods to quantify changes in the microvascular network and red blood cell perfusion around the sensors using noninvasive intravital microscopy and laser Doppler flowmetry are described. The feasibility of combining interstitial glucose monitoring from an implanted sensor with intravital fluorescence microscopy was explored using a bolus injection of fluorescein and dextrose to observe real-time mass transport of a small molecule at the sensor-tissue interface. The percutaneous window chamber provides an excellent model for assessing the influence of different sensor modifications, such as surface morphologies, on neovascularization using real-time monitoring of the microvascular network and tissue perfusion. However, the tissue response to an implanted sensor was variable, and some sensors migrated entirely out of the field of view and could not be observed adequately. A percutaneous optical window provides direct, real-time images of the development and dynamics of microvascular networks, microvessel patency, and fibrotic encapsulation at the tissue-sensor interface. Additionally, observing microvessels following combined bolus injections of a fluorescent dye and glucose in the local sensor environment demonstrated a valuable technique to visualize mass transport at the sensor surface.

[Percutaneous renal puncture guide by a novel real-time needle-tracking ultrasound system for percutaneous nephrolithotomy: analysis of 16 cases].

PubMed

Ma, Kai; Huang, Xiao-bo; Xiong, Liu-lin; Xu, Qing-quan; Xu, Tao; Ye, Hai-yun; Yu, Lu-ping; Wang, Xiao-feng

2014-08-18

To evaluate the feasibility and efficacy of percutaneous renal puncture in percutaneous nephrolithotomy guided by novel needle-tracking ultrasound system. From may to october 2013, 16 cases of percutaneous nephrolithotomy were performed under the guidance of ultrasound system. The clinical data including the time of completing percutaneous renal puncture, the color of urine sucked out from the kidney calices, and the complications were analyzed retrospectively. Of the 16 patients, 18 percutaneous renal access were established guided by ultrasound system. All of them were successtul for the first time, and the average time of completing percutaneous renal punctures was (26.90 ± 11.37) s (15 to 54 s). After the operation, the hemoglobin decreased by (9.56 ± 5.27)%(1.41% to 24.06%), and no complications occurred except for postoperative fever in 2 case. The novel ultrasound system is a safe and effective technique that can reduce the technical difficulty of percutaneous renal puncture in percutaneous nephrolithotomy.

Intraprocedural left ventricular free wall rupture diagnosed by left ventriculogram in a patient with infero-posterior myocardial infarction and severe aortic stenosis.

PubMed

Konishi, Takao; Funayama, Naohiro; Yamamoto, Tadashi; Nishihara, Hiroshi; Hotta, Daisuke; Kikuchi, Kenjiro; Yokoyama, Hideo; Ohori, Katsumi

2016-06-06

Left ventricular wall rupture remains a major lethal complication of acute myocardial infarction and hypertension is a well-known predisposing factor of cardiac rupture after myocardial infarction. An 87-year-old man was admitted to our hospital, diagnosed as acute myocardial infarction (AMI). The echocardiogram showed 0.67-cm(2) aortic valve, consistent with severe aortic stenosis (AS). A coronary angiography showed a chronic occlusion of the proximal left circumflex artery and a 99 % stenosis and thrombus in the mid right coronary artery. During percutaneous angioplasty of the latter, transient hypotension and bradycardia developed at the time of balloon inflation, and low doses of noradrenaline and etilefrine were intravenously administered as needed. The patient suddenly lost consciousness and developed electro-mechanical dissociation. Cardio-pulmonary resuscitation followed by insertion of an intra-aortic balloon pump (IABP) and percutaneous cardiopulmonary support were initiated. The echocardiogram revealed moderate pericardial effusion, though the site of free wall rupture was not distinctly visible. A left ventriculogram clearly showed an infero-posterior apical wall rupture. Surgical treatment was withheld because of the interim development of brain death. In this patient, who presented with severe AS, the administration of catecholamine to stabilize the blood pressure probably increased the intraventricular pressures considerably despite apparently normal measurements of the central aortic pressure. IABP, temporary pacemaker, or both are recommended instead of intravenous catecholamines for patients with AMI complicated with significant AS to stabilize hemodynamic function during angioplasty.

Exercise Dynamics in Secondary Mitral Regurgitation: Pathophysiology and Therapeutic Implications

PubMed Central

Bertrand, Philippe B.; Schwammenthal, Ehud; Levine, Robert A.; Vandervoort, Pieter M.

2016-01-01

Secondary mitral valve regurgitation (MR) remains a challenging problem in the diagnostic work-up and treatment of heart failure patients. Although secondary MR is characteristically dynamic in nature and sensitive to changes in ventricular geometry and loading, current therapy is mainly focused on resting conditions. Exercise-induced increase in secondary MR, however, is associated with impaired exercise capacity and increased mortality. In an era where a multitude of percutaneous solutions are emerging for the treatment of HF patients it becomes important to address the dynamic component of secondary MR during exercise as well. A critical reappraisal of the underlying disease mechanisms, and in particular of the dynamic component during exercise is of timely importance. This review summarizes the pathophysiologic mechanisms involved in the dynamic deterioration of secondary MR during exercise, its functional and prognostic impact, and the way current treatment options affect the dynamic lesion and exercise hemodynamics in general. PMID:28093494

Percutaneous intrapericardial echocardiography during catheter ablation: a feasibility study.

PubMed

Horowitz, Barbara Natterson; Vaseghi, Marmar; Mahajan, Aman; Cesario, David A; Buch, Eric; Valderrábano, Miguel; Boyle, Noel G; Ellenbogen, Kenneth A; Shivkumar, Kalyanam

2006-11-01

Percutaneous pericardial access, epicardial mapping, and ablation have been used successfully for catheter ablation procedures. The purpose of this study was to evaluate the safety and feasibility of closed-chest direct epicardial ultrasound imaging for aiding cardiac catheter ablation procedures. An intracardiac ultrasound catheter was used for closed-chest epicardial imaging of the heart in 10 patients undergoing percutaneous epicardial access for catheter ablation. All patients underwent concomitant intracardiac echocardiography and preprocedural transesophageal echocardiography. Using a double-wire technique, two sheaths were placed in the pericardium, and a phased-array ultrasound catheter was manipulated within the pericardial sinuses for imaging. Multiple images from varying angles were obtained for catheter navigation. Notably, image stability was excellent, and structures such as the left atrial appendage were seen in great detail. No complications resulting from use of the ultrasound catheter in the pericardium occurred, and no restriction of movement due to the presence of the additional catheter in the pericardial space was observed. Wall motion was correlated to voltage maps in five patients and showed that areas of scars correlated with wall-motion abnormalities. Normal wall-motion score correlated to sensed signals of 4.2 +/- 0.3 mV (normal myocardium >1.5 mV), and scores >1 correlated to areas with signals <0.5 mV in that territory). Intrapericardial imaging using an ultrasound catheter is feasible and safe and has the potential to provide additional valuable information for complex ablation procedures.

Overview of Orion Crew Module and Launch Abort Vehicle Dynamic Stability

NASA Technical Reports Server (NTRS)

Owens, Donald B.; Aibicjpm. Vamessa V.

2011-01-01

With the retirement of the Space Shuttle, NASA is designing a new spacecraft, called Orion, to fly astronauts to low earth orbit and beyond. Characterization of the dynamic stability of the Orion spacecraft is important for the design of the spacecraft and trajectory construction. Dynamic stability affects the stability and control of the Orion Crew Module during re-entry, especially below Mach = 2.0 and including flight under the drogues. The Launch Abort Vehicle is affected by dynamic stability as well, especially during the re-orientation and heatshield forward segments of the flight. The dynamic stability was assessed using the forced oscillation technique, free-to-oscillate, ballistic range, and sub-scale free-flight tests. All of the test techniques demonstrated that in heatshield-forward flight the Crew Module and Launch Abort Vehicle are dynamically unstable in a significant portion of their flight trajectory. This paper will provide a brief overview of the Orion dynamic aero program and a high-level summary of the dynamic stability characteristics of the Orion spacecraft.

[Echo-guided radiofrequency percutaneous ablation of hepatocellular carcinoma in cirrhosis using a cooled needle].

PubMed

Marone, G; Francica, G; D'Angelo, V; Iodice, G; Pastore, P; Altamura, G; Cusati, B; Siani, A

1998-06-01

Radiofrequency hyperthermia using the newly-developed "cooled-tip" needle is one of the latest US-guided percutaneous treatments of hepatocellular carcinoma arising in cirrhosis. The continuous cooling of the needle tip allows tissue heating and necrosis far from the electrode without tissue charring, which was the major drawback of the old monopolar technique. Herein we report our preliminary results on feasibility and effectiveness of the thermoablation of mono- or paucifocal hepatocellular carcinoma with the cooled-tip needle. November, 1996, to January, 1998, we treated thirteen cirrhotic patients (mean age 69.5 yrs, 10 men, 12 HCV-positive; 11 in Child's Class A and 2 in Class B) with 19 hepatocellular carcinoma nodules (mean diameter: 27 mm; range: 10-41 mm; 6 with diameter > 3 cm). None of the patients had portal thrombosis and/or extrahepatic spread. We used a radiofrequency generator (100 W power) connected to an 18 G perfusion electrode needle with an exposed tip of 2-3 cm. The circuit is closed through a dispersive electrode positioned under the patient's thighs. A peristaltic pump infuses a chilled (2-5 degrees C) saline solution to guarantee the continuous cooling of the needle tip. The needle was placed into target lesions under US guidance. The interventional procedure was carried out under general anesthesia using Propofol without intubation. Dynamic CT (more recently with the helical technique) was carried out 15-20 days after thermoablation to assess treatment efficacy. In all, 31 thermal injuries (at 1000-1200 mA for 10-15 minutes) were caused in 21 sessions in the 19 hepatocellular carcinoma nodules (mean: 1.5 lesions per nodule and 1.6 sessions per patient). Complete necrosis as assessed at dynamic CT (no enhancement during the arteriographic phase) was achieved in 16 of 19 nodules (84%). No side-effects occurred. During the follow-up (median: 11 months) no death occurred and five patients had recurrent hepatocellular carcinoma appearing either as single nodule or as multinodular liver involvement. In our experience radiofrequency hyperthermia with the cooled-tip needle permits effective and safe percutaneous ablation of HCC in cirrhosis. In addition, treatment time is short and lesions > 3 cm can be treated. Further experience is needed to better define the role of percutaneous thermoablation in the treatment strategy of hepatocellular carcinoma.

Intra-cardiac Embolism of a Large Bone Cement Material after Percutaneous Vertebroplasty Removed through a Combination of an Endovascular Procedure and an Inferior Vena Cava Exploration: a Case Report.

PubMed

Park, Jin-Sung; Kim, Jaedong; Lee, Yonggu; Gwon, Jun-Gyo; Park, Ye-Soo

2018-05-07

Percutaneous vertebroplasty (PVP) is a minimally invasive surgical treatment for patients with osteoporotic vertebral compression fracture (OVCF) and can rapidly alleviate pain, improve mobility, and stabilize the vertebrae. However, it has the potential to cause complications such as cement embolism. A 55-year-old female presented with pain in the lumbar region as a chief complaint. PVP was performed after diagnosis of acute OVCFs at L4 and L5. No abnormal symptoms were reported after surgery, but a large cement embolism was observed in her right atrium and ventricle. After discussion in a multi-disciplinary team, the large cement embolism was successfully removed by a combination of endovascular procedure and an inferior vena cava exploration. Surgeons must consider the possibility of intra-cardiac cement embolism after PVP. A hybrid approach of an endovascular procedure and a vascular surgery may be a reasonable treatment option to minimize the surgical procedure in cases of a large intra-cardiac cement embolism.

Local Dynamic Stability Associated with Load Carrying

PubMed Central

Lockhart, Thurmon E

2013-01-01

Objectives Load carrying tasks are recognized as one of the primary occupational factors leading to slip and fall injuries. Nevertheless, the mechanisms associated with load carrying and walking stability remain illusive. The objective of the current study was to apply local dynamic stability measure in walking while carrying a load, and to investigate the possible adaptive gait stability changes. Methods Current study involved 25 young adults in a biomechanics research laboratory. One tri-axial accelerometer was used to measure three-dimensional low back acceleration during continuous treadmill walking. Local dynamic stability was quantified by the maximum Lyapunov exponent (maxLE) from a nonlinear dynamics approach. Results Long term maxLE was found to be significant higher under load condition than no-load condition in all three reference axes, indicating the declined local dynamic stability associated with load carrying. Conclusion Current study confirmed the sensitivity of local dynamic stability measure in load carrying situation. It was concluded that load carrying tasks were associated with declined local dynamic stability, which may result in increased risk of fall accident. This finding has implications in preventing fall accidents associated with occupational load carrying. PMID:23515183

Comparison of dynamic postural stability scores between athletes with and without chronic ankle instability during lateral jump landing.

PubMed

Shiravi, Zeinab; Shadmehr, Azadeh; Moghadam, Saeed Talebian; Moghadam, Behrouz Attarbashi

2017-01-01

Many ankle injuries occur while participating in sports that require jumping and landing such as basketball, volleyball and soccer. Most recent studies have investigated dynamic postural stability of patients with chronic ankle instability after landing from a forward jump. The present study aimed to investigate the dynamic postural stability of the athletes who suffer from chronic ankle sprain while landing from a lateral jump. Twelve athletes with self-reported unilateral chronic ankle instability (4 females and 8 males) and 12 matched controls (3 females and 9 males) voluntarily participated in the study. Dynamic postural stability index and its directional indices were measured while performing lateral jump landing test. No differences were found between athletes with and without chronic ankle instability during our landing protocol by means of the dynamic postural stability index and its directional indices. Findings showed that in each group, medial/lateral stability index is significantly higher than anterior/posterior and vertical stability indexes. Findings showed that dynamic postural stability was not significantly different between the two groups. Future studies should examine chronic ankle instability patients with more severe disabilities and expose them to more challenging dynamic balance conditions to further explore postural stability. IIIa.

Early Postoperative Results of Percutaneous Needle Fasciotomy in 451 Patients with Dupuytren Disease.

PubMed

Molenkamp, Sanne; Schouten, Tanneke A M; Broekstra, Dieuwke C; Werker, Paul M N; Moolenburgh, J Daniel

2017-06-01

Percutaneous needle fasciotomy is a minimally invasive treatment modality for Dupuytren disease. In this study, the authors analyzed the efficacy and complication rate of percutaneous needle fasciotomy using a statistical method that takes the multilevel structure of data, regarding multiple measurements from the same patient, into account. The data of 470 treated rays from 451 patients with Dupuytren disease that underwent percutaneous needle fasciotomy were analyzed retrospectively. The authors described the early postoperative results of percutaneous needle fasciotomy and applied linear mixed models to compare mean correction of passive extension deficit between joints and efficacy of primary versus secondary percutaneous needle fasciotomy. Mean preoperative passive extension deficits at the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints were 37, 40, and 31 degrees, respectively. Mean preoperative total passive extension deficit was 54 degrees. Results were excellent, with a mean total passive extension deficit correction of 85 percent. Percutaneous needle fasciotomy was most effective for metacarpophalangeal joints and less effective for proximal interphalangeal and distal interphalangeal joints. Secondary percutaneous needle fasciotomy was as effective as primary percutaneous needle fasciotomy. Complications were rare and mostly minor. The results of this study confirm that percutaneous needle fasciotomy is an effective and safe treatment modality for patients with mild to moderate disease who prefer a minimally invasive procedure. Therapeutic, IV.

Structural Stability of Mathematical Models of National Economy

NASA Astrophysics Data System (ADS)

Ashimov, Abdykappar A.; Sultanov, Bahyt T.; Borovskiy, Yuriy V.; Adilov, Zheksenbek M.; Ashimov, Askar A.

2011-12-01

In the paper we test robustness of particular dynamic systems in a compact regions of a plane and a weak structural stability of one dynamic system of high order in a compact region of its phase space. The test was carried out based on the fundamental theory of dynamical systems on a plane and based on the conditions for weak structural stability of high order dynamic systems. A numerical algorithm for testing the weak structural stability of high order dynamic systems has been proposed. Based on this algorithm we assess the weak structural stability of one computable general equilibrium model.

14 CFR 23.181 - Dynamic stability.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Dynamic stability. 23.181 Section 23.181... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Flight Stability § 23.181 Dynamic... that the function of a stability augmentation system, reference § 23.672, is needed to meet the flight...

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

Carrafiello, Gianpaolo, E-mail: gcarraf@tin.it; Lagana, Domenico; Cotta, Elisa

The purpose of this study was to evaluate the safety and efficacy of percutaneous ultrasound (US)-guided radiofrequency ablation (RFA) in patients with intrahepatic cholangiocarcinoma (ICCA) in a small, nonrandomized series. From February 2004 to July 2008, six patients (four men and two women; mean age 69.8 years [range 48 to 83]) with ICCA underwent percutaneous US-guided RFA. Preintervetional transarterial embolization was performed in two cases to decrease heat dispersion during RFA in order to increase the area of ablation. The efficacy of RFA was evaluated using contrast-enhanced dynamic computed tomography (CT) 1 month after treatment and then every 3 monthsmore » thereafter. Nine RFA sessions were performed for six solid hepatic tumors in six patients. The duration of follow-up ranged from 13 to 21 months (mean 17.5). Posttreatment CT showed total necrosis in four of six tumors after one or two RFA sessions. Residual tumor was observed in two patients with larger tumors (5 and 5.8 cm in diameter). All patients tolerated the procedure, and there with no major complications. Only 1 patient developed post-RFA syndrome (pain, fever, malaise, and leukocytosis), which resolved with oral administration of acetaminophen. Percutaneous RFA is a safe and effective treatment for patients with hepatic tumors: It is ideally suited for those who are not eligible for surgery. Long-term follow-up data regarding local and systemic recurrence and survival are still needed.« less

Removal of a Trapped Endoscopic Catheter from the Gallbladder via Percutaneous Transhepatic Cholecystostomy: Technical Innovation

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

Stay, Rourke M.; Sonnenberg, Eric van; Goodacre, Brian W.

2006-12-15

Background. Percutaneous cholecystostomy is used for a variety of clinical problems. Methods. Percutaneous cholecystostomy was utilized in a novel setting to resolve a problematic endoscopic situation. Observations. Percutaneous cholecystostomy permitted successful removal of a broken and trapped endoscopic biliary catheter, in addition to helping treat cholecystitis. Conclusion. Another valuable use of percutaneous cholecystostomy is demonstrated, as well as emphasizing the importance of the interplay between endoscopists and interventional radiologists.

Evaluation of Renal Function after Percutaneous Nephrolithotomy-Does the Number of Percutaneous Access Tracts Matter?

PubMed

Gorbachinsky, Ilya; Wood, Kyle; Colaco, Marc; Hemal, Sij; Mettu, Jayadev; Mirzazadeh, Majid; Assimos, Dean G; Gutierrez-Aćeves, Jorge

2016-07-01

Renal function following percutaneous nephrolithotomy has long been a concern to urologists, especially in the setting of multi-tract access. We determined whether the risk of renal injury after multi-tract percutaneous nephrolithotomy was greater than after a single access approach. We retrospectively reviewed the records of 307 consecutive patients treated with percutaneous nephrolithotomy from 2011 to 2012 at Wake Forest Health. Perioperative (99m)Tc-mercaptoacetyltriglycine nuclear renogram parameters along with serum creatinine values were assessed within 1 year of the procedure. Patients were stratified by single access vs multi-access (2 or more). We identified 110 cases in which renography was done before and after percutaneous nephrolithotomy. A total of 74 patients (67.3%) underwent single access percutaneous nephrolithotomy while 36 (32.7%) underwent multi-access percutaneous nephrolithotomy. Serum creatinine did not significantly differ between the 2 cohorts postoperatively (p = 0.09). There was a significant 2.28% decrease in renal function based on mercaptoacetyltriglycine nuclear renogram results after percutaneous nephrolithotomy of the affected kidney in patients with multiple accesses (p <0.01). This relationship was not observed when patients were stratified by multiple comorbidities associated with nephrolithiasis. Multi-access percutaneous nephrolithotomy is associated with a small reduction in the function of the targeted kidney compared to a single access approach. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

An alternative and inexpensive percutaneous access needle in pediatric patients.

PubMed

Penbegul, Necmettin; Soylemez, Haluk; Bozkurt, Yasar; Sancaktutar, Ahmet Ali; Bodakci, Mehmet Nuri; Hatipoglu, Namik Kemal; Atar, Murat; Yildirim, Kadir

2012-10-01

The most important factor that increases the cost of percutaneous surgery is the disposable instruments used for the surgery. In this study we present the advantages of using an intravenous cannula instead of a percutaneous access needle for renal access. Recently, percutaneous stone surgery has grown in use in pediatric cases and is considered a minimally invasive surgery. The most important step in this surgery is access to the renal collecting systems. Although fluoroscopy has been used frequently at this stage, the use of ultrasound has recently increased. During percutaneous accesses under all types of imaging techniques, disposable 11- to 15-cm-long 18-ga needles are used. In pediatric cases, these longer needles are difficult to use. Using disposable materials in percutaneous nephrolithotomy increases the cost of the procedure. Therefore, we asserted that percutaneous access especially in pediatric cases could be performed using a 16-ga intravenous cannula (angiocath). Indeed, percutaneous access was performed successfully, especially in pediatric preschool patients. Shorter needle length, easy skin entry, comfort of manipulation, clear visualization of the metal needle on ultrasound, and wide availability can be considered advantages of this method. The angiocath is also less expensive than a percutaneous access needle. Angiocath is inexpensive, easily available, and practical, and it is the shortest needle to perform percutaneous access in pediatric patients. Copyright © 2012 Elsevier Inc. All rights reserved.

Clinical investigations on the spinal osteoblastic metastasis treated by combination of percutaneous vertebroplasty and (125)I seeds implantation versus radiotherapy.

PubMed

Yang, Zuozhang; Tan, Jing; Zhao, Ruilian; Wang, Jiaping; Sun, Hongpu; Wang, Xiaoxue; Xu, Lei; Jiang, Hua; Zhang, Jinlei

2013-02-01

To investigate the clinical efficacy of combining digital subtraction angiography-guided percutaneous vertebroplasty (PVP) and (125)I seeds implantation for the treatment of spinal osteoplastic metastasis. A combination of PVP and (125)I implantation was conducted for 50 patients with spinal osteoplastic metastasis, while the other 50 patients who received regular radiation therapy were used as a comparison. Visual analogue pain scale (VAS) and score of life quality (EORTCQLQ-30) were determined for all the patients. Surgery was successful in 89 spinal segments of vertebral body in 50 patients. Each segment of vertebral body was injected with 1-5 mL (2.8 mL for thoracic and 3.1 mL for lumbar vertebral body on average) of bone cement. Postoperative X-ray and CT examination showed that all the patients in the PVP group achieved spinal stability. During the follow-up examination from 6 months to 5 years, 49 patients (98.0%) had significantly relieved back pain, and only 1 case (2.0%) had no obvious improvement. Postoperative VAS score and Karnofsky performance score (KPS) were significantly different from the preoperative scores (p<0.05); and compared to the regular treatment group, PVP combined (125)I seeds showed much better clinical efficacy (p<0.05). PVP is a minimally invasive treatment with easy operation and less complications. PVP can effectively relieve the pain, stabilize the spine, improve the life quality, and reduce the occurrence of paraplegia in patients with spinal osteoplastic metastasis. Utilization of (125)I seeds with PVP can enhance the clinical efficacy.

Calculation of the lateral-dynamic stability of aircraft

NASA Technical Reports Server (NTRS)

Raikh, A

1952-01-01

Graphs and formulas are given with the aid of which all the aerodynamic coefficients required for computing the lateral dynamic stability can be determined. A number of numerical examples are given for obtaining the stability derivatives and solving the characteristic-stability equation. Approximate formulas are derived with the aid of which rapid preliminary computations may be made and the stability coefficients corrected for certain modifications of the airplane. A derivation of the lateral-dynamic-stability equations is included.

Geometrical analysis of the LiCN vibrational dynamics: a stability geometrical indicator.

PubMed

Vergel, A; Benito, R M; Losada, J C; Borondo, F

2014-02-01

The vibrational dynamics of the LiNC/LiCN molecular system is examined making use of the Riemannian geometry. Stability and chaoticity are analyzed, in this context, by means of the Jacobi-Levi-Civita equations, derived from the Jacobi metric, and its solutions. A dynamical indicator, called stability geometrical indicator, is introduced in order to ascertain the dynamical characteristics of stability and chaos in the molecule under study.

Percutaneous transgastric irrigation drainage in combination with endoscopic necrosectomy in necrotizing pancreatitis (with videos).

PubMed

Raczynski, Susanne; Teich, Niels; Borte, Gudrun; Wittenburg, Henning; Mössner, Joachim; Caca, Karel

2006-09-01

Endoscopic drainage of pancreatic acute and chronic pseudocysts and pancreatic necrosectomy have been shown to be beneficial for critically ill patients, with complete endoscopic resolution rates of around 80%. Our purpose was to describe an improved endoscopic technique used to treat pancreatic necrosis. Case report. University hospital. Two patients with large retroperitoneal necroses were treated with percutaneous transgastric retroperitoneal flushing tubes and a percutaneous transgastric jejunal feeding tube by standard percutaneous endoscopic gastrostomy access in addition to endoscopic necrosectomy. Intensive percutaneous transgastric flushing in combination with percutaneous normocaloric enteral nutrition and repeated endoscopic necrosectomy led to excellent outcomes in both patients. Small number of patients. The "double percutaneous endoscopic gastrostomy" approach for simultaneous transgastric drainage and normocaloric enteral nutrition in severe cases of pancreatic necroses is safe and effective. It could be a promising improvement to endoscopic transgastric treatment options in necrotizing pancreatitis.

Acute oral and percutaneous toxicity of pesticides to mallards: Correlations with mammalian toxicity data

USGS Publications Warehouse

Hudson, R.H.; Haegele, M.A.; Tucker, R.K.

1979-01-01

Acute oral (po) and 24-hr percutaneous (perc) LD50 values for 21 common pesticides (19 anticholinesterases, of which 18 were organophosphates, and one was a carbamate; one was an organochlorine central nervous system stimulant; and one was an organonitrogen pneumotoxicant) were determined in mallards (Anas platyrhynchos). Three of the pesticides tested were more toxic percutaneously than orally. An index to the percutaneous hazard of a pesticide, the dermal toxicity index (DTI = po LD50/perc LD50 ? 100), was also calculated for each pesticide. These toxicity values in mallards were compared with toxicity data for rats from the literature. Significant positive correlations were found between log po and log percutaneous LD50 values in mallards (r = 0.65, p 0.10). Variations in percutaneous methodologies are discussed with reference to interspecies variation in toxicity values. It is recommended that a mammalian DTI value approaching 30 be used as a guideline for the initiation of percutaneous toxicity studies in birds, when the po LD50 and/or projected percutaneous LD50 are less than expected field exposure levels.

Animal models for percutaneous-device-related infections: a review.

PubMed

Shao, Jinlong; Kolwijck, Eva; Jansen, John A; Yang, Fang; Walboomers, X Frank

2017-06-01

This review focuses on the construction of animal models for percutaneous-device-related infections, and specifically the role of inoculation of bacteria in such models. Infections around percutaneous devices, such as catheters, dental implants and limb prostheses, are a recurrent and persistent clinical problem. To promote the research on this clinical problem, the establishment of a reliable and validated animal model would be of keen interest. In this review, literature related to percutaneous devices was evaluated, and particular attention was paid to studies involving the use of bacteria. The design of percutaneous devices, susceptibility of various animal species, bacterial strains, amounts of bacteria, method of inoculation and methods for subsequent evaluation of the infection are discussed in detail. Given that an ideal animal model for study of percutaneous-device-related infection is still not existent, this article presents the basis for the construction of such a standardized animal model for percutaneous-device-related infection studies. The inoculation of bacteria is critical to obtain an animal model for standardized studies for percutaneous-device-related infections. Copyright © 2017. Published by Elsevier B.V.

Postoperative quality-of-life assessment in patients with spine metastases treated with long-segment pedicle-screw fixation.

PubMed

Bernard, Florian; Lemée, Jean-Michel; Lucas, Olivier; Menei, Philippe

2017-06-01

OBJECTIVE In recent decades, progress in the medical management of cancer has been significant, resulting in considerable extension of survival for patients with metastatic disease. This has, in turn, led to increased attention to the optimal surgical management of bone lesions, including metastases to the spine. In addition, there has been a shift in focus toward improving quality of life and reducing hospital stay for these patients, and many minimally invasive techniques have been introduced with the aim of reducing the morbidity associated with more traditional open approaches. The goal of this study was to assess the efficacy of long-segment percutaneous pedicle screw stabilization for the treatment of instability associated with thoracolumbar spine metastases in neurologically intact patients. METHODS This study was a retrospective review of data from a prospective database. The authors analyzed cases in which long-segment percutaneous pedicle screw fixation was performed for the palliative treatment of thoracolumbar spinal instability due to spinal metastases in neurologically intact patients. All of the patients included in the study underwent surgery between January 2014 and May 2015 at the authors' institution. Postoperative radiation therapy was planned within 10 days following the stabilization in all cases. Clinical and radiological follow-up assessments were planned for 3 days, 3 weeks, 6 weeks, 3 months, 6 months, and 1 year after surgery. Outcome was assessed by means of standard postoperative evaluation and oncological and spinal quality of life measures (European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Version 3.0 [EORTC QLQ-C30] and Oswestry Disability Index [ODI], respectively). Moreover, 5 patients were given an activity monitoring device for recording the distance walked daily; preoperative and postoperative daily distances were compared. RESULTS Data from 17 cases were analyzed. There were no complications, and patients showed improvement in pain level and quality of life from the early postoperative period on. The mean ODI score was 62.7 (range 40-84) preoperatively, 35.4 (range 24-59) on postoperative Day 3, and 46.1 (range 30-76) at 3 weeks, 37.6 (range 25-59) at 6 weeks, 34.0 (range 24-59) at 3 months, 39.1 (range 22-64) at 6 months, and 30.0 (range 20-55) at 1 year after screw placement. The mean ODI was significantly improved in the first 45 days (p < 0.001). Improvement was also evident in scores for functional and symptomatic scales of the EORTC QLQ-C30. All patients underwent postoperative radiation therapy within 10 days (mean 7.5). All patients (n = 5) with an activity monitoring device showed improvement in daily walking distance. CONCLUSIONS Less-invasive palliative treatment for advanced spinal metastases is promising as part of a multidisciplinary approach to the care of patients with metastatic disease. The results of this study indicate that percutaneous surgery may allow for rapid improvement in quality of life and walking ability for patients with thoracolumbar instability due to spine metastases. Long-segment percutaneous screw fixation followed by early radiation therapy appears to be a safe and effective treatment option for providing solid and durable stability and improved quality of life for these patients.

Fast Virtual Fractional Flow Reserve Based Upon Steady-State Computational Fluid Dynamics Analysis: Results From the VIRTU-Fast Study.

PubMed

Morris, Paul D; Silva Soto, Daniel Alejandro; Feher, Jeroen F A; Rafiroiu, Dan; Lungu, Angela; Varma, Susheel; Lawford, Patricia V; Hose, D Rodney; Gunn, Julian P

2017-08-01

Fractional flow reserve (FFR)-guided percutaneous intervention is superior to standard assessment but remains underused. The authors have developed a novel "pseudotransient" analysis protocol for computing virtual fractional flow reserve (vFFR) based upon angiographic images and steady-state computational fluid dynamics. This protocol generates vFFR results in 189 s (cf >24 h for transient analysis) using a desktop PC, with <1% error relative to that of full-transient computational fluid dynamics analysis. Sensitivity analysis demonstrated that physiological lesion significance was influenced less by coronary or lesion anatomy (33%) and more by microvascular physiology (59%). If coronary microvascular resistance can be estimated, vFFR can be accurately computed in less time than it takes to make invasive measurements.

Comparison of endoscopic and percutaneous drainage of symptomatic necrotic collections in acute necrotizing pancreatitis.

PubMed

Woo, Shanan; Walklin, Ryan; Ackermann, Travis; Lo, Sheng Wei; Shilton, Hamish; Pilgrim, Charles; Evans, Peter; Burnes, James; Croagh, Daniel

2018-05-10

Primary endoscopic and percutaneous drainage for pancreatic necrotic collections is increasingly used. We aim to compare the relative effectiveness of both modalities in reducing the duration and severity of illness by measuring their effects on systemic inflammatory response syndrome (SIRS). We retrospectively reviewed all cases of endoscopic and percutaneous drainage for pancreatic necrotic collections performed in 2011-2016 at two hospitals. We assessed the post-procedure length of hospital stay, reduction in C-reactive protein levels, resolution of SIRS, the complication rates, and the number of procedures required for resolution. Thirty-two patients were identified and 57 cases (36 endoscopic, 21 percutaneous) were included. There was no significant difference in C-reactive protein reduction between endoscopic and percutaneous drainage (69.5% vs 68.8%, P = 0.224). Resolution of SIRS was defined as the post-procedure normalization of white cell count (endoscopic vs percutaneous: 70.4% vs 64.3%, P = 0.477), temperature (endoscopic vs percutaneous: 93.3% vs 60.0%, P = 0.064), heart rate (endoscopic vs percutaneous: 56.0% vs 11.1%, P = 0.0234), and respiratory rate (endoscopic vs percutaneous: 83.3% vs 0.0%, P = 0.00339). Post-procedure length of hospital stay was 27 days with endoscopic drainage and 46 days with percutaneous drainage (P = 0.0183). Endoscopic drainage was associated with a shorter post-procedure length of hospital stay and a greater rate of normalization of SIRS parameters than percutaneous drainage, although only the effects on heart rate and respiratory rate reached statistical significance. Further studies are needed to establish which primary drainage modality is superior for pancreatic necrotic collections. © 2018 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and John Wiley & Sons Australia, Ltd.

Bicellar systems as a new colloidal delivery strategy for skin.

PubMed

Rubio, L; Rodríguez, G; Barbosa-Barros, L; Alonso, C; Cócera, M; de la Maza, A; Parra, J L; López, O

2012-04-01

The presented work evaluates the use of bicellar systems as new delivery vectors for controlled release of compounds through the skin. Two different active principles were introduced into the bicellar systems: diclofenac diethylamine (DDEA) and flufenamic acid (Ffa). Bicellar systems are discoidal aggregates formed by long and short alkyl chain phospholipids. Characterization of the bicellar systems by dynamic light scattering (DLS) and cryogenic transmission electron microscopy (Cryo-TEM) showed that particle size decreased when DDEA was encapsulated and increased when Ffa was included in the bicellar systems. Percutaneous absorption studies demonstrated a lower penetration of DDEA and Ffa through the skin when the drugs were included in the bicellar systems than when the drugs were applied in an aqueous solution (DDEA) and in an ethanolic solution (Ffa); the reduction in penetration was more pronounced with Ffa. These bicellar systems may have retardant effects on percutaneous absorption, which result in a promising strategy for future drug or cosmetic delivery applications. Copyright © 2011 Elsevier B.V. All rights reserved.

Intralesional sclerotherapy for subcutaneous venous malformations in children.

PubMed

Uehara, Shuichiro; Osuga, Keigo; Yoneda, Akihiro; Oue, Takaharu; Yamanaka, Hiroaki; Fukuzawa, Masahiro

2009-08-01

Venous malformations (VMs) involve multiple anatomical spaces and encase critical neuromuscular structures, making surgical treatment difficult. Recently sclerotherapy has been suggested as the primary treatment for VMs instead of surgical intervention. This report represents eight cases of children with VMs treated with direct percutaneous injections of sclerosing agents, such as ethanol, polidocanol or ethanolamine oleate. All eight patients had large lesions (>3 cm) located on the head, foot, neck and face. Sclerotherapy was performed in an angiographic suite under general anesthesia. Prior to sclerotherapy, percutaneous phlebography was performed in order to visualize the dynamic situation inside the lesion and the draining flow into the adjacent venous vascular system. A 2-15 ml of sclerosing agent was injected into VM lesions under fluoroscopy. An evaluation by MRI examination showed that 6 out of 8 patients had remission, and alleviation of their symptoms without major complications, furthermore one of the lesions apparently disappeared. Intralesional sclerotherapy provides a simple, safe and effective treatment for VMs in the subcutaneous lesions in children.

Fractional Stability of Trunk Acceleration Dynamics of Daily-Life Walking: Toward a Unified Concept of Gait Stability

PubMed Central

Ihlen, Espen A. F.; van Schooten, Kimberley S.; Bruijn, Sjoerd M.; Pijnappels, Mirjam; van Dieën, Jaap H.

2017-01-01

Over the last decades, various measures have been introduced to assess stability during walking. All of these measures assume that gait stability may be equated with exponential stability, where dynamic stability is quantified by a Floquet multiplier or Lyapunov exponent. These specific constructs of dynamic stability assume that the gait dynamics are time independent and without phase transitions. In this case the temporal change in distance, d(t), between neighboring trajectories in state space is assumed to be an exponential function of time. However, results from walking models and empirical studies show that the assumptions of exponential stability break down in the vicinity of phase transitions that are present in each step cycle. Here we apply a general non-exponential construct of gait stability, called fractional stability, which can define dynamic stability in the presence of phase transitions. Fractional stability employs the fractional indices, α and β, of differential operator which allow modeling of singularities in d(t) that cannot be captured by exponential stability. The fractional stability provided an improved fit of d(t) compared to exponential stability when applied to trunk accelerations during daily-life walking in community-dwelling older adults. Moreover, using multivariate empirical mode decomposition surrogates, we found that the singularities in d(t), which were well modeled by fractional stability, are created by phase-dependent modulation of gait. The new construct of fractional stability may represent a physiologically more valid concept of stability in vicinity of phase transitions and may thus pave the way for a more unified concept of gait stability. PMID:28900400

Temporary Mechanical Circulatory Support: A Review of the Options, Indications, and Outcomes

PubMed Central

Gilotra, Nisha A; Stevens, Gerin R

2014-01-01

Cardiogenic shock remains a challenging disease entity and is associated with significant morbidity and mortality. Temporary mechanical circulatory support (MCS) can be implemented in an acute setting to stabilize acutely ill patients with cardiomyopathy in a variety of clinical situations. Currently, several options exist for temporary MCS. We review the indications, contraindications, clinical applications, and evidences for a variety of temporary circulatory support options, including the intra-aortic balloon pump (IABP), extracorporeal membrane oxygenation (ECMO), CentriMag blood pump, and percutaneous ventricular assist devices (pVADs), specifically the TandemHeart and Impella. PMID:25674024

Vibration waveform effects on dynamic stabilization of ablative Rayleigh-Taylor instability

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

Piriz, A. R.; Lucchio, L. Di; Rodriguez Prieto, G.

2011-08-15

An analysis of dynamic stabilization of Rayleigh-Taylor instability in an ablation front is performed by considering a general square wave for modulating the vertical acceleration of the front. Such a kind of modulation allows for clarifying the role of thermal conduction in the mechanism of dynamic stabilization. In addition, the study of the effect of different modulations by varying the duration and amplitude of the square wave in each half-period provides insight on the optimum performance of dynamic stabilization.

Fluctuating interaction network and time-varying stability of a natural fish community

NASA Astrophysics Data System (ADS)

Ushio, Masayuki; Hsieh, Chih-Hao; Masuda, Reiji; Deyle, Ethan R.; Ye, Hao; Chang, Chun-Wei; Sugihara, George; Kondoh, Michio

2018-02-01

Ecological theory suggests that large-scale patterns such as community stability can be influenced by changes in interspecific interactions that arise from the behavioural and/or physiological responses of individual species varying over time. Although this theory has experimental support, evidence from natural ecosystems is lacking owing to the challenges of tracking rapid changes in interspecific interactions (known to occur on timescales much shorter than a generation time) and then identifying the effect of such changes on large-scale community dynamics. Here, using tools for analysing nonlinear time series and a 12-year-long dataset of fortnightly collected observations on a natural marine fish community in Maizuru Bay, Japan, we show that short-term changes in interaction networks influence overall community dynamics. Among the 15 dominant species, we identify 14 interspecific interactions to construct a dynamic interaction network. We show that the strengths, and even types, of interactions change with time; we also develop a time-varying stability measure based on local Lyapunov stability for attractor dynamics in non-equilibrium nonlinear systems. We use this dynamic stability measure to examine the link between the time-varying interaction network and community stability. We find seasonal patterns in dynamic stability for this fish community that broadly support expectations of current ecological theory. Specifically, the dominance of weak interactions and higher species diversity during summer months are associated with higher dynamic stability and smaller population fluctuations. We suggest that interspecific interactions, community network structure and community stability are dynamic properties, and that linking fluctuating interaction networks to community-level dynamic properties is key to understanding the maintenance of ecological communities in nature.

[Case-control study on minimally invasive percutaneous locking compression plate internal fixation for the treatment of type II and III pilon fractures].

PubMed

Zhang, Zhi-Da; Ye, Xiu-Yi; Shang, Li-Yong; Xu, Rong-Ming; Zhu, Yan-Zhao

2011-12-01

To explore the clinical efficacy of delayed open reduction and internal fixation with minimally invasive percutaneous locking compression plate for the treatment of type II and III Pilon fractures. From January 2007 to September 2009, 32 patients with type II and III Pilon fractures were treated with open reduction and anatomic plate fixation (AP group) and minimally invasive percutaneous locking compression plate osteosynthesis (LCP group). There were 11 males and 6 females in AP group, with an average age of (37.4 +/- 13.3) years (ranged, 19 to 55 years). And there were 10 males and 5 females in LCP group, with an average age of (34.6 +/- 11.3) years(ranged, 21 to 56 years). The operating time, fracture healing time, aligned angulation and ankle function were compared between the two groups. All the patients were followed up, and the during ranged from 12 to 25 months, with a mean of (15.0 +/- 1.7) months. The average operation time was (76.5 +/- 8.3) min for AP group and (58.3 +/- 3.4) min for LCP group; the average time of fracture healing was (20.5 +/- 0.4) weeks for AP group and (15.7 +/- 0.2) weeks for LCP group; the total angulation between anterior posterior film and lateral film was averaged (6.6 +/- 0.5) degrees for AP group and (3.6 +/- 0.2) degrees for LCP group. As to above index, the results of LCP group were better than those of AP group (P < 0.05). According to Kofoed criteria for ankle joint, the results of LCP group were better than those of AP group in ankle joint pain, wakling and ankle joint function (P < 0.05). The method of minimally invasive percutaneous locking compression plate internal fixation is effective in the treatment of Pilon fracture with less invasion, faster bone union, more stabilized fixation, quicker recovery of ankle function and fewer complications, which is more advantaged for type II and III Pilon fractures.

[Dynamic plantar pressure distribution after percutaneous hallux valgus correction using the Reverdin-Isham osteotomy].

PubMed

Rodríguez-Reyes, Gerardo; López-Gavito, Eduardo; Pérez-Sanpablo, Alberto Isaac; Galván Duque-Gastélum, Carlos; Alvarez-Camacho, Michelín; Mendoza-Cruz, Felipe; Parra-Téllez, Patricia; Vázquez-Escamilla, Jesús; Quiñones-Urióstegui, Ivett

2014-07-01

Percutaneous surgical techniques are suitable for the correction of the hallux valgus deformity. Satisfactory aesthetic and functional results obtained with the Reverdin- Isham osteotomy have been reported. The aim of this study was to describe dynamic plantar pressure redistribution after the correction of the deformity using this technique. A sample of 20 feet with mild or moderate hallux valgus was conformed and surgically treated using the Reverdin-Isham osteotomy. Clinical, radiological, surface and pressure assessments were performed pre and postoperatively. Postoperative mean (± SD) values of the American Orthopaedic Foot and Ankle Society (AOFAS) score, metatarsophalangeal, first intermetatarsal and proximal articular sect angles were 95.7 (3.3), 15.5° (5.4), 9.5° (1.5) y 5.3° (3.0), respectively. A significant decrease was observed in surface values of both lateral (P = 0.003) and medial (P = 0.001) masks of the forefoot. Mean pressure values of the lateral forefoot region denoted a significant increase (P < 0.001) while the medial forefoot region showed no change (P = 0.137). There is evidence that this particular surgical technique promotes a new plantar pressure pattern in the foot that might significantly favour the increase of the pressure observed under the lesser metatarsal heads and might not induce meaningful changes in the mean pressure registered under the first metatarsal head and hallux.

Surgical vs percutaneous radiofrequency ablation for hepatocellular carcinoma in dangerous locations

PubMed Central

Huang, Ji-Wei; Hernandez-Alejandro, Roberto; Croome, Kristopher P; Yan, Lu-Nan; Wu, Hong; Chen, Zhe-Yu; Prasoon, Pankaj; Zeng, Yong

2011-01-01

AIM: To compare the long-term outcome of percutaneous vs surgical radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) in dangerous locations. METHODS: One hundred and sixty-two patients with HCC in dangerous locations treated with percutaneous or surgical RFA were enrolled in this study. The patients were divided into percutaneous RFA group and surgical RFA group. After the patients were regularly followed up for a long time, their curative rate, hospital stay time, postoperative complications and 5-year local tumor progression were compared and analyzed. RESULTS: No significant difference was observed in curative rate between the two groups (91.3% vs 96.8%, P = 0.841). The hospital stay time was longer and more analgesics were required while the incidence of bile duct injury and RFA-related hemorrhage was lower in surgical RFA group than in percutaneous RFA group (P < 0.05). The local progression rate of HCC in dangerous locations was significantly lower in surgical RFA group than in percutaneous RFA group (P = 0.05). The relative risk of local tumor progression was 14.315 in percutaneous RFA group. CONCLUSION: The incidence of severe postoperative complications and local tumor progression is lower after surgical RFA than after percutaneous RFA. PMID:21218093

Extrapedicular Infiltration Anesthesia as an Improved Method of Local Anesthesia for Unipedicular Percutaneous Vertebroplasty or Percutaneous Kyphoplasty.

PubMed

Liu, Liehua; Cheng, Shiming; Lu, Rui; Zhou, Qiang

2016-01-01

Aim. This report introduces extrapedicular infiltration anesthesia as an improved method of local anesthesia for unipedicular percutaneous vertebroplasty or percutaneous kyphoplasty. Method. From March 2015 to March 2016, 44 patients (11 males and 33 females) with osteoporotic vertebral compression fractures with a mean age of 71.4 ± 8.8 years (range: 60 to 89) received percutaneous vertebroplasty or percutaneous kyphoplasty. 24 patients were managed with conventional local infiltration anesthesia (CLIA) and 20 patients with both CLIA and extrapedicular infiltration anesthesia (EPIA). Patients evaluated intraoperative pain by means of the visual analogue score and were monitored during the procedure for additional sedative analgesia needs and for adverse nerve root effects. Results. VAS of CLIA + EPIA and CLIA group was 2.5 ± 0.7 and 4.3 ± 1.0, respectively, and there was significant difference ( P = 0.001). In CLIA group, 1 patient required additional sedative analgesia, but in CLIA + EPIA group, no patients required that. In the two groups, no adverse nerve root effects were noted. Summary. Extrapedicular infiltration anesthesia provided good local anesthetic effects without significant complications. This method deserves further consideration for use in unipedicular percutaneous vertebroplasty and percutaneous kyphoplasty.

A novel technique of percutaneous stone extraction in choledocholithiasis after cholecystostomy.

PubMed

Lim, Kyoung Hoon; Kim, Yong Joo

2013-05-01

To evaluate the technical feasibility and clinical efficacy of percutaneous common bile duct stone extraction via cystic duct after percutaneous cholecystostomy. Twenty-five consecutive patients with choledocholithiasis underwent percutaneous stone extraction under conscious sedation. The stones were extracted through the 12-Fr sheath using Wittich nitinol stone basket under fluoroscopic guidance via cystic duct after percutaneous trnas-hepatic cholecystostomy. Common bile duct stones were successfully removed in 22 of the 25 patients (88%) by this new technique. The causes of failure in three patients were bile leakage, hematoma of the gallbladder and failure of cystic duct cannulation. Cystic duct injury during this procedure did not occur and there was no post-procedure mortality. The mean period of indwelling catheter was 8.7±4.6 days and the mean duration of hospitalization was 13.4±5.9 days. Percutaneous commmon bile duct stone extraction via the cystic duct through percutaneous cholecystostomy route is effective and feasible for treating choledocholithiasis.

Percutaneous extracorporeal life support for patients in therapy refractory cardiogenic shock: initial results of an interdisciplinary team.

PubMed

Guenther, Sabina; Theiss, Hans D; Fischer, Matthias; Sattler, Stefan; Peterss, Sven; Born, Frank; Pichlmaier, Maximilian; Massberg, Steffen; Hagl, Christian; Khaladj, Nawid

2014-03-01

Therapy refractory cardiogenic shock is associated with dismal outcome. Percutaneous implantation of an extracorporeal life support (ECLS) system achieves immediate cardiopulmonary stabilization, sufficient end-organ perfusion and reduction of subsequent multiorgan failure (MOF). Forty-one patients undergoing percutaneous ECLS implantation for cardiogenic shock from February 2012 until August 2013 were retrospectively analysed. Mean age was 52 ± 13 years, 6 (15%) were female. Mean pH values obtained before ECLS implantation were 7.15 ± 0.24, mean lactate concentration was 11.7 ± 6.4 mmol/l. Levels obtained 6 h after ECLS implantation were 7.30 ± 0.14 and 8.7 ± 5.0 mmol/l, respectively. In 23 patients (56%) cardiogenic shock resulted from an acute coronary syndrome in 13 (32%) from cardiomyopathy, in 5 (12%) from other causes. Twenty-seven (66%) had been resuscitated, in 14 (34%) implantation was performed under ongoing cardiopulmonary resuscitation (CPR). Of note, 97% of the acute coronary syndrome patients underwent percutaneous coronary intervention (PCI) either before ECLS implantation or under ECLS support. Extracorporeal life support implantation was performed on scene (Emergency Department, Cath Lab, Intensive Care Unit) by a senior cardiac surgeon and a trained perfusionist, in 8 cases (20%) in the referring hospital. Thirty-day mortality was 51% [21 patients, due to MOF (n = 14), cerebral complications (n = 6) and heart failure (n = 1)]. Logistic regression analysis identified 6-h pH values as an independent risk factor of 30-day mortality (P < 0.001, OR = 0.000, 95% CI 0.000-0.042). Neither CPR nor implantation under ongoing CPR resulted in significant differences. In 26 cases (63%), the ECLS system could be explanted, after mean support of 169 ± 67 h. Seven of these patients received cardiac surgery [ventricular assist device implantation (n = 4), heart transplantation (n = 1), other procedures (n = 2)]. Due to the evolution of transportable ECLS systems and percutaneous techniques implantation on scene is feasible. Extracorporeal life support may serve as a bridge-to-decision and bridge-to-treatment device. Neurological evaluation before ventricular assist device implantation and PCI under stable conditions are possible. Despite substantial mortality, ECLS implantation in selected patients by an experienced team offers additional support to conventional therapy as well as CPR and allows survival in patients that otherwise most likely would have died. This concept has to be implemented in cardiac survival networks in the future.

Orbital venous malformation: percutaneous treatment using an electrolytically detachable fibred coil.

PubMed

Diolaiuti, Sara; Iizuka, Tateyuki; Schroth, Gerhard; Remonda, Luca; Laedrach, Kurt; El-Koussy, Marwan; Frueh, Beatrice E; Goldblum, David

2009-03-01

To report the efficacy of percutaneous treatment of an orbital venous malformation with an electrolytically detachable fibred coil. We report an instance of radiography-guided percutaneous treatment with an electrolytically detachable fibred coil in a 16-year-old boy with acute, spontaneous, painless proptosis on the left side, which progressed with time. Magnetic resonance imaging, angiography and orbitophlebography revealed a low-flow, intraorbital venous malformation. Percutaneous puncture and drainage were followed by a short remission. Following an acute recurrence, a single detachable fibred coil was deployed via a percutaneous approach under angiographic guidance. No radiological or clinical recurrences were observed over 4 years. Embolization of a deep orbital venous malformation with detachable fibred coils via a percutaneous approach can be highly effective, and may be considered before proceeding with open surgery.

Dynamic Stability Experiment of Maglev Systems,

DTIC Science & Technology

1995-04-01

This report summarizes the research performed on maglev vehicle dynamic stability at Argonne National Laboratory during the past few years. It also... maglev system, it is important to consider this phenomenon in the development of all maglev systems. This report presents dynamic stability experiments...on maglev systems and compares their numerical simulation with predictions calculated by a nonlinear dynamic computer code. Instabilities of an

The role of interventional radiology in abdominopelvic trauma

PubMed Central

Ierardi, Anna Maria; Duka, Ejona; Lucchina, Natalie; Floridi, Chiara; De Martino, Alessandro; Donat, Daniela; Fontana, Federico

2016-01-01

The management of trauma patients has evolved in recent decades owing to increasing availability of advanced imaging modalities such as CT. Nowadays, CT has replaced the diagnostic function of angiography. The latter is considered when a therapeutic option is hypothesized. Arterial embolization is a life-saving procedure in abdominopelvic haemorrhagic patients, reducing relevant mortality rates and ensuring haemodynamic stabilization of the patient. Percutaneous transarterial embolization has been shown to be effective for controlling ongoing bleeding for patients with high-grade abdominopelvic injuries, thereby reducing the failure rate of non-operative management, preserving maximal organ function. Surgery is not always the optimal solution for stabilization of a patient with polytrauma. Mini-invasivity and repeatability may be considered as relevant advantages. We review technical considerations, efficacy and complication rates of hepatic, splenic, renal and pelvic embolization to extrapolate current evidence about transarterial embolization in traumatic patients. PMID:26642310

Stability of Dynamical Systems with Discontinuous Motions:

NASA Astrophysics Data System (ADS)

Michel, Anthony N.; Hou, Ling

In this paper we present a stability theory for discontinuous dynamical systems (DDS): continuous-time systems whose motions are not necessarily continuous with respect to time. We show that this theory is not only applicable in the analysis of DDS, but also in the analysis of continuous dynamical systems (continuous-time systems whose motions are continuous with respect to time), discrete-time dynamical systems (systems whose motions are defined at discrete points in time) and hybrid dynamical systems (HDS) (systems whose descriptions involve simultaneously continuous-time and discrete-time). We show that the stability results for DDS are in general less conservative than the corresponding well-known classical Lyapunov results for continuous dynamical systems and discrete-time dynamical systems. Although the DDS stability results are applicable to general dynamical systems defined on metric spaces (divorced from any kind of description by differential equations, or any other kinds of equations), we confine ourselves to finite-dimensional dynamical systems defined by ordinary differential equations and difference equations, to make this paper as widely accessible as possible. We present only sample results, namely, results for uniform asymptotic stability in the large.

Designing Inter-Organisational Collectivities for Dynamic Fit: Stability, maneuvrability and Application in Disaster Relief Endeavours

DTIC Science & Technology

2011-01-01

changed consumer preferences . Hence, static stability limits initial performance deviation (e.g., maintaining desired airplane altitude, maintaining...by changed consumer preferences . Hence, dynamic stability limits the duration of performance deviation (e.g., maintaining desired airplane altitude...altitude from wind gust. Initial resistance to deviation in profit level from change in consumer preferences . Dynamic stability Quickness of a

DYNAMIC NEUROMUSCULAR STABILIZATION & SPORTS REHABILITATION

PubMed Central

Kobesova, Alena; Kolar, Pavel

2013-01-01

Dynamic neuromuscular (core) stability is necessary for optimal athletic performance and is not achieved purely by adequate strength of abdominals, spinal extensors, gluteals or any other musculature; rather, core stabilization is accomplished through precise coordination of these muscles and intra‐abdominal pressure regulation by the central nervous system. Understanding developmental kinesiology provides a framework to appreciate the regional interdependence and the inter‐linking of the skeleton, joints, musculature during movement and the importance of training both the dynamic and stabilizing function of muscles in the kinetic chain. The Dynamic Neuromuscular Stabilization (DNS) approach provides functional tools to assess and activate the intrinsic spinal stabilizers in order to optimize the movement system for both pre‐habilitation and rehabilitation of athletic injuries and performance. Level of Evidence: 5 PMID:23439921

Stability-Constrained Aerodynamic Shape Optimization with Applications to Flying Wings

NASA Astrophysics Data System (ADS)

Mader, Charles Alexander

A set of techniques is developed that allows the incorporation of flight dynamics metrics as an additional discipline in a high-fidelity aerodynamic optimization. Specifically, techniques for including static stability constraints and handling qualities constraints in a high-fidelity aerodynamic optimization are demonstrated. These constraints are developed from stability derivative information calculated using high-fidelity computational fluid dynamics (CFD). Two techniques are explored for computing the stability derivatives from CFD. One technique uses an automatic differentiation adjoint technique (ADjoint) to efficiently and accurately compute a full set of static and dynamic stability derivatives from a single steady solution. The other technique uses a linear regression method to compute the stability derivatives from a quasi-unsteady time-spectral CFD solution, allowing for the computation of static, dynamic and transient stability derivatives. Based on the characteristics of the two methods, the time-spectral technique is selected for further development, incorporated into an optimization framework, and used to conduct stability-constrained aerodynamic optimization. This stability-constrained optimization framework is then used to conduct an optimization study of a flying wing configuration. This study shows that stability constraints have a significant impact on the optimal design of flying wings and that, while static stability constraints can often be satisfied by modifying the airfoil profiles of the wing, dynamic stability constraints can require a significant change in the planform of the aircraft in order for the constraints to be satisfied.

Is the Routine Check Nephrostogram Following Percutaneous Antegrade Ureteric Stent Placement Necessary?

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

Soh, Keng Chuan; Tay, Kiang Hiong, E-mail: tay.kiang.hiong@sgh.com.sg; Tan, Bien Soo

2008-05-15

Our aim was to review our experience with percutaneous antegrade ureteric stent (PAUS) placement and to determine if the routinely conducted check nephrostogram on the day following ureteric stent placement was necessary. Retrospective review of patients who had undergone PAUS placement between January 2004 and December 2005 was performed. There were 83 subjects (36 males, 47 females), with a mean age of 59.9 years (range, 22-94 years). Average follow-up duration was 7.1 months (range, 1-24 months). The most common indications for PAUS placement were ureteric obstruction due to metastatic disease (n = 56) and urinary calculi (n = 34). Technicalmore » success was 93.2% (96/103 attempts), with no major immediate procedure-related complications or mortalities. The Bard 7Fr Urosoft DJ Stent was used in more than 95% of the cases. Eighty-one of 89 (91.0%) check nephrostograms demonstrated a patent ureteric stent with resultant safety catheter removal. Three check nephrostograms revealed distal stent migration requiring repositioning by a goose-snare, while five others showed stent occlusion necessitating permanent external drainage by nephrostomy drainage catheter reinsertion. Following PAUS placement, the serum creatinine level improved or stabilized in 82% of patients. The serum creatinine outcome difference between the groups with benign and malignant indications for PAUS placement was not statistically significant (p = 0.145) but resolution of hydronephrosis was significantly better (p = 0.008) in patients with benign indications. Percutaneous antegrade ureteric stent placement is a safe and effective means of relief for ureteric obstruction. The check nephrostogram following ureteric stent placement was unnecessary in the majority of patients.« less

Axial presacral lumbar interbody fusion and percutaneous posterior fixation for stabilization of lumbosacral isthmic spondylolisthesis.

PubMed

Gerszten, Peter C; Tobler, William; Raley, Thomas J; Miller, Larry E; Block, Jon E; Nasca, Richard J

2012-04-01

Case series. To describe a minimally invasive surgical technique for treatment of lumbosacral spondylolisthesis. Traditional surgical management of lumbosacral spondylolisthesis is technically challenging and associated with significant complications. Minimally invasive surgical techniques offer patients treatment alternatives with lower operative morbidity risk. The combination of percutaneous pedicle screw reduction and an axial presacral approach for lumbosacral discectomy and fusion is an option for the surgical management of low-grade lumbosacral spondylolisthesis. Twenty-six consecutive patients with symptomatic L5-S1 level isthmic spondylolisthesis (grade 1 or grade 2) underwent axial presacral lumbar interbody fusion and percutaneous posterior fixation. Study outcomes included visual analogue scale for axial pain severity, Odom criteria, and radiographic fusion. The procedure was successfully completed in all patients with no intraoperative complications reported. Intraoperative blood loss was minimal (range, 20-150 mL). Median hospital stay was 1 day (range, <1-2 d). Spondylolisthesis grade was improved after axial lumbar interbody fusion (P<0.001) with 50% (13 of 26) of patients showing a reduction of at least 1 grade. Axial pain severity improved from 8.1±1.4 at baseline to 2.8±2.3 after axial lumbar interbody fusion, representing a 66% reduction from baseline (95% confidence interval, 54.3%-77.9%). At 2-year posttreatment, all patients showed solid fusion. Using Odom criteria, 81% of patients were judged as excellent or good (16 excellent, 5 good, 3 fair, and 2 poor). There were no perioperative procedure-related complications including infection or bowel perforation. During postoperative follow-up, 4 patients required reintervention due to recurrent radicular (n=2) or screw-related (n=2) pain. The minimally invasive presacral axial interbody fusion and posterior instrumentation technique is a safe and effective treatment for low-grade isthmic spondylolisthesis.

Feasibility and efficacy of the 2.5 L and 3.8 L impella percutaneous left ventricular support device during high-risk, percutaneous coronary intervention in patients with severe aortic stenosis.

PubMed

Spiro, Jon; Venugopal, Vinod; Raja, Yogesh; Ludman, Peter F; Townend, Jonathan N; Doshi, Sagar N

2015-05-01

Assessment of the feasibility and outcomes of the 2.5 L and 3.8 L Impella cardiac pump in patients with severe aortic stenosis (AS) and left ventricular impairment undergoing percutaneous revascularization (PCI) with or without balloon aortic valvuloplasty (BAV). We reviewed the clinical and procedural findings from a consecutive series of unselected patients with severe AS who underwent PCI during Impella support. In addition, we describe novel "balloon-assist" techniques that allowed implantation of Impella into the left ventricle (LV) when initial unassisted attempts failed. Five patients with severe AS were identified (four males, age 78.2 years, aortic valve area (AVA) 0.6 cm(2) , left ventricular ejection fraction (LVEF) 24 ± 5%, mean Society of Thoracic Surgeons (STS) mortality 11% (range 3-17%)). The Impella catheter traversed the aortic valve (AV) unassisted in only one patient, with four cases requiring balloon-assist techniques. All patients underwent planned revascularisation; mean procedure time 177 min (range 135-252 min), mean number of stents 3.4 (range 1-8), with three patients requiring rotational atherectomy. All procedures were well tolerated, with absence of arrhythmia, hypotension, pulmonary edema, stroke, or myocardial infarction. One patient died 48 hr post-PCI of multi-organ failure. The four remaining patients were well at 30 days. Implantation of the 2.5 and 3.8 L Impella appears feasible in patients with severe AS and left ventricle (LV) impairment. A balloon-assist technique may be used to facilitate device implantation when initial unassisted attempts fail. Improved hemodynamic stability may enhance the tolerability of lengthy and complex procedures. © 2014 Wiley Periodicals, Inc.

Textile for heart valve prostheses: fabric long-term durability testing.

PubMed

Heim, Frederic; Durand, Bernard; Chakfe, Nabil

2010-01-01

The rapid developments and success in percutaneous vascular surgery over the last two decades with the now common stent grafts implantation, make the noninvasive surgery technique today attractive even for heart valve replacement. Less traumatic for the patient and also less time consuming, percutaneous heart valve replacement is however at its beginning and restricted to end of life patients. The noninvasive procedure expects from the heart valve prosthesis material to be resistant and adapted to folding requirements of the implantation process (catheter). Polyester fabric could be a suited material for heart valve implanted percutaneously. Highly flexible and resistant, polyester fabric proved to be well adapted to the dynamic behavior of a valve and polyester (Dacron) is also widely used for vascular grafts implantation and shows good biocompatibility and durability. However, today there's no data available on long-term durability of fabric used as heart valve material. The purpose of this work is to study the long term behavior of a microdenier polyester fabric construction under combined in vitro flexure and tension fatigue stress. In the novel in vitro testing technique presented, a fabric specimen was subjected to combined flexural and tensile fatigue generated by fluid flow under physiological pressure conditions. The results obtained show how flexural properties change with fatigue time, which reflects directly on the suitability of a fabric in such devices. It was also observed that these fabric structural changes directly influence the in vitro behavior of the textile heart valve prosthesis. (c) 2009 Wiley Periodicals, Inc.

Investigation of biomechanical behavior of lumbar vertebral segments with dynamic stabilization device using finite element approach

NASA Astrophysics Data System (ADS)

Deoghare, Ashish B.; Kashyap, Siddharth; Padole, Pramod M.

2013-03-01

Degenerative disc disease is a major source of lower back pain and significantly alters the biomechanics of the lumbar spine. Dynamic stabilization device is a remedial technique which uses flexible materials to stabilize the affected lumbar region while preserving the natural anatomy of the spine. The main objective of this research work is to investigate the stiffness variation of dynamic stabilization device under various loading conditions under compression, axial rotation and flexion. Three dimensional model of the two segment lumbar spine is developed using computed tomography (CT) scan images. The lumbar structure developed is analyzed in ANSYS workbench. Two types of dynamic stabilization are considered: one with stabilizing device as pedicle instrumentation and second with stabilization device inserted around the inter-vertebral disc. Analysis suggests that proper positioning of the dynamic stabilization device is of paramount significance prior to the surgery. Inserting the device in the posterior region indicates the adverse effects as it shows increase in the deformation of the inter-vertebral disc. Analysis executed by positioning stabilizing device around the inter-vertebral disc yields better result for various stiffness values under compression and other loadings. [Figure not available: see fulltext.

Early clinical outcomes of primary percutaneous coronary intervention in bharatpur, Nepal.

PubMed

Dubey, Laxman; Bhattacharya, Rabindra; Guruprasad, Sogunuu; Subramanyam, Gangapatnam

2013-06-01

Primary percutaneous coronary intervention represents one of the cornerstone management modalities for patients with acute ST-elevation myocardial infarction and has undergone tremendous growth over the past two decades. This study was aimed to determine the early clinical outcomes of primary percutaneous coronary interventions in a tertiary-level teaching hospital without onsite cardiac surgery backup. This was a prospective descriptive study which included all consecutive patients who were admitted for primary percutaneous coronary interventions between March 2011 and January 2013 at the College of Medical Sciences and Teaching Hospital, Bharatpur, Nepal. Total 68 patients underwent primary percutaneous coronary interventions as a mode of revascularization. The primary end point of the study was to identify in-hospital as well as 30-day clinical outcomes of primary percutaneous coronary interventions. The mean age was 56.31 ± 11.47 years, with age range of 32 years to 91 years. Of the 68 primary percutaneous coronary interventions performed, 15 (22.05%) were carried out in women and 10 (14.70%) in patients over 75 years of age. Primary percutaneous coronary intervention for anterior wall myocardial infarction was more common than for non-anterior wall myocardial infarction (55.88% vs. 44.12%). Proximal artery stenting was performed in 38.50% and the non proximal artery stenting in 61.50%. The outcomes were mortality (5.88%), cardiogenic shock (5.88%), contrast-induced nephropathy requiring dialysis (2.94%), arrhythmias requiring treatment (4.41%), early stent thrombosis (2.94%) and minor complications (14.70%). Primary percutaneous coronary intervention improves the early clinical outcomes in patient with acute ST-elevation myocardial infarction. Despite having no onsite cardiac surgery backup, primary percutaneous coronary intervention was feasible with acceptable complications in a tertiary-care teaching hospital.

Safety and Effectiveness of Percutaneously Inserted Peritoneal Ports Compared to Surgically Inserted Ports in a Retrospective Study of 87 Patients with Ovarian Carcinoma over a 10-Year Period

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

Woodley-Cook, Joel, E-mail: jwoodleycook@gmail.com; Tarulli, Emidio; Tan, Kong T.

PurposePlacement of peritoneal ports has become a favorable technique for direct chemotherapy infusion in treating peritoneal metastases from ovarian cancer. We aim to outline an approach to the percutaneous insertion of peritoneal ports and to characterize success and complication rates compared to surgically inserted ports.Materials and MethodsRetrospective analysis was collected from 87 patients who had peritoneal port insertion (28 inserted surgically and 59 percutaneously) for treatment of peritoneal metastases from ovarian cancer from July 2004 to July 2014. Complications were classified according to the SIR Clinical Practice Guidelines as major or minor.ResultsTechnical success rates for surgically and percutaneously inserted portsmore » were 100 and 96.7 %, respectively (p = 0.44), with the two percutaneous failures successful at a later date. There were no major complications in either group. Minor complication rates for surgically versus percutaneously inserted ports were 46.4 versus 22.0 %, respectively (p = 0.02). The infection rate for surgically inserted versus percutaneously inserted ports was 14.3 and 0 %, respectively (p = 0.002). The relative risk of developing a complication from percutaneous peritoneal port insertion without ascites was 3.4 (p = 0.04). For percutaneously inserted ports, the mean in-room procedure time was 81 ± 1.3 min and mean fluoroscopy time was 5.0 ± 4.5 min.ConclusionPercutaneously inserted peritoneal ports are a safe alternative to surgically inserted ports, demonstrating similar technical success and lower complication rates.« less

Dynamic Stabilization of a Quantum Many-Body Spin System

NASA Astrophysics Data System (ADS)

Hoang, T. M.; Gerving, C. S.; Land, B. J.; Anquez, M.; Hamley, C. D.; Chapman, M. S.

2013-08-01

We demonstrate dynamic stabilization of a strongly interacting quantum spin system realized in a spin-1 atomic Bose-Einstein condensate. The spinor Bose-Einstein condensate is initialized to an unstable fixed point of the spin-nematic phase space, where subsequent free evolution gives rise to squeezing and quantum spin mixing. To stabilize the system, periodic microwave pulses are applied that rotate the spin-nematic many-body fluctuations and limit their growth. The stability diagram for the range of pulse periods and phase shifts that stabilize the dynamics is measured and compares well with a stability analysis.

CT-guided percutaneous screw fixation plus cementoplasty in the treatment of painful bone metastases with fractures or a high risk of pathological fracture.

PubMed

Pusceddu, Claudio; Fancellu, Alessandro; Ballicu, Nicola; Fele, Rosa Maria; Sotgia, Barbara; Melis, Luca

2017-04-01

To evaluate the feasibility and effectiveness of computed tomography (CT)-guided percutaneous screw fixation plus cementoplasty (PSFPC), for either treatment of painful metastatic fractures or prevention of pathological fractures, in patients who are not candidates for surgical stabilization. Twenty-seven patients with 34 metastatic bone lesions underwent CT-guided PSFPC. Bone metastases were located in the vertebral column, femur, and pelvis. The primary end point was the evaluation of feasibility and complications of the procedure, in addition to the length of hospital stay. Pain severity was estimated before treatment and 1 and 6 months after the procedure using the visual analog scale (VAS). Functional outcome was assessed by improved patient walking ability. All sessions were completed and well tolerated. There were no complications related to either incorrect positioning of the screws during bone fixation or leakage of cement. All patients were able to walk within 6 h after the procedure and the average length of hospital stay was 2 days. The mean VAS score decreased from 7.1 (range, 4-9) before treatment to 1.6 (range, 0-6), 1 month after treatment, and to 1.4 (range 0-6) 6 months after treatment. Neither loosening of the screws nor additional bone fractures occurred during a median follow-up of 6 months. Our results suggest that PSFPC might be a safe and effective procedure that allows the stabilization of the fracture and the prevention of pathological fractures with significant pain relief and good recovery of walking ability, although further studies are required to confirm this preliminary experience.

Single-Institution Results of Image-Guided Nonplugged Percutaneous Versus Transjugular Liver Biopsy

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

Hardman, Rulon L., E-mail: hardmanr@uthscsa.edu; Perrich, Kiley D.; Silas, Anne M.

2011-04-15

Purpose: To retrospectively review patients who underwent transjugular and image-guided percutaneous biopsy and compare the relative risk of ascites, thrombocytopenia, and coagulopathy. Materials and Methods: From August 2001 through February 2006, a total of 238 liver biopsies were performed. The radiologist reviewed all patient referrals for transjugular biopsy. These patients either underwent transjugular biopsy or were reassigned to percutaneous biopsy (crossover group). Patients referred to percutaneous image-guided liver biopsy underwent this same procedure. Biopsies were considered successful if a tissue diagnosis could be made from the samples obtained. Results: A total of 36 transjugular biopsies were performed with 3 totalmore » (8.3%) and 1 major (2.8%) complications. A total of 171 percutaneous biopsies were performed with 10 (5.8%) total and 3 (1.8%) major complications. The crossover group showed a total of 4 (12.9%) complications with 1 (3.2%) major complication. Sample adequacy was 91.9% for transjugular and 99.5% for percutaneous biopsy. Conclusion: Both transjugular and percutaneous liver biopsy techniques are efficacious and safe. Contraindications such as thrombocytopenia, coagulopathy, and ascites are indicators of greater complications but are not necessarily prevented by transjugular biopsy. Percutaneous biopsy more frequently yields a diagnostic specimen than transjugular biopsy.« less

The application of percutaneous endoscopic colostomy to the management of obstructed defecation.

PubMed

Heriot, A G; Tilney, H S; Simson, J N L

2002-05-01

We describe the case of a 52-year woman with a 17-year history of obstructed defecation in whom all other standard treatments had failed and the patient had refused a colostomy. Her symptoms were controlled by percutaneous endoscopic colostomy with antegrade colonic irrigation. A percutaneous endoscopic colostomy tube was placed in the sigmoid colon endoscopically using a colonoscope and the patient irrigated two liters of water through the percutaneous endoscopic colostomy twice each day and was able to successfully evacuate her rectum without excess straining or discomfort. Percutaneous endoscopic colostomy is an alternative option to colostomy in the management of obstructed defecation.

Unifying dynamical and structural stability of equilibria

NASA Astrophysics Data System (ADS)

Arnoldi, Jean-François; Haegeman, Bart

2016-09-01

We exhibit a fundamental relationship between measures of dynamical and structural stability of linear dynamical systems-e.g. linearized models in the vicinity of equilibria. We show that dynamical stability, quantified via the response to external perturbations (i.e. perturbation of dynamical variables), coincides with the minimal internal perturbation (i.e. perturbations of interactions between variables) able to render the system unstable. First, by reformulating a result of control theory, we explain that harmonic external perturbations reflect the spectral sensitivity of the Jacobian matrix at the equilibrium, with respect to constant changes of its coefficients. However, for this equivalence to hold, imaginary changes of the Jacobian's coefficients have to be allowed. The connection with dynamical stability is thus lost for real dynamical systems. We show that this issue can be avoided, thus recovering the fundamental link between dynamical and structural stability, by considering stochastic noise as external and internal perturbations. More precisely, we demonstrate that a linear system's response to white-noise perturbations directly reflects the intensity of internal white-noise disturbance that it can accommodate before becoming stochastically unstable.

Unifying dynamical and structural stability of equilibria.

PubMed

Arnoldi, Jean-François; Haegeman, Bart

2016-09-01

We exhibit a fundamental relationship between measures of dynamical and structural stability of linear dynamical systems-e.g. linearized models in the vicinity of equilibria. We show that dynamical stability, quantified via the response to external perturbations (i.e. perturbation of dynamical variables), coincides with the minimal internal perturbation (i.e. perturbations of interactions between variables) able to render the system unstable. First, by reformulating a result of control theory, we explain that harmonic external perturbations reflect the spectral sensitivity of the Jacobian matrix at the equilibrium, with respect to constant changes of its coefficients. However, for this equivalence to hold, imaginary changes of the Jacobian's coefficients have to be allowed. The connection with dynamical stability is thus lost for real dynamical systems. We show that this issue can be avoided, thus recovering the fundamental link between dynamical and structural stability, by considering stochastic noise as external and internal perturbations. More precisely, we demonstrate that a linear system's response to white-noise perturbations directly reflects the intensity of internal white-noise disturbance that it can accommodate before becoming stochastically unstable.

Percutaneous pulmonary and tricuspid valve implantations: An update

PubMed Central

Wagner, Robert; Daehnert, Ingo; Lurz, Philipp

2015-01-01

The field of percutaneous valvular interventions is one of the most exciting and rapidly developing within interventional cardiology. Percutaneous procedures focusing on aortic and mitral valve replacement or interventional treatment as well as techniques of percutaneous pulmonary valve implantation have already reached worldwide clinical acceptance and routine interventional procedure status. Although techniques of percutaneous pulmonary valve implantation have been described just a decade ago, two stent-mounted complementary devices were successfully introduced and more than 3000 of these procedures have been performed worldwide. In contrast, percutaneous treatment of tricuspid valve dysfunction is still evolving on a much earlier level and has so far not reached routine interventional procedure status. Taking into account that an “interdisciplinary challenging”, heterogeneous population of patients previously treated by corrective, semi-corrective or palliative surgical procedures is growing inexorably, there is a rapidly increasing need of treatment options besides redo-surgery. Therefore, the review intends to reflect on clinical expansion of percutaneous pulmonary and tricuspid valve procedures, to update on current devices, to discuss indications and patient selection criteria, to report on clinical results and finally to consider future directions. PMID:25914786

Assessment of Walking Stability of Elderly by Means of Nonlinear Time-Series Analysis and Simple Accelerometry

NASA Astrophysics Data System (ADS)

Ohtaki, Yasuaki; Arif, Muhammad; Suzuki, Akihiro; Fujita, Kazuki; Inooka, Hikaru; Nagatomi, Ryoichi; Tsuji, Ichiro

This study presents an assessment of walking stability in elderly people, focusing on local dynamic stability of walking. Its main objectives were to propose a technique to quantify local dynamic stability using nonlinear time-series analyses and a portable instrument, and to investigate their reliability in revealing the efficacy of an exercise training intervention for elderly people for improvement of walking stability. The method measured three-dimensional acceleration of the upper body, and computation of Lyapunov exponents, thereby directly quantifying the local stability of the dynamic system. Straight level walking of young and elderly subjects was investigated in the experimental study. We compared Lyapunov exponents of young and the elderly subjects, and of groups before and after the exercise intervention. Experimental results demonstrated that the exercise intervention improved local dynamic stability of walking. The proposed method was useful in revealing effects and efficacies of the exercise intervention for elderly people.

Dynamic stabilization of Rayleigh-Taylor instability: Experiments with Newtonian fluids as surrogates for ablation fronts

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

Rodriguez Prieto, G.; Piriz, A. R.; Lopez Cela, J. J.

2013-01-15

A previous theory on dynamic stabilization of Rayleigh-Taylor instability at interfaces between Newtonian fluids is reformulated in order to make evident the analogy of this problem with the related one on dynamic stabilization of ablation fronts in the framework of inertial confinement fusion. Explicit analytical expressions are obtained for the boundaries of the dynamically stable region which turns out to be completely analogue to the stability charts obtained for the case of ablation fronts. These results allow proposing experiments with Newtonian fluids as surrogates for studying the case of ablation fronts. Experiments with Newtonian fluids are presented which demonstrate themore » validity of the theoretical approach and encourage to pursue experimental research on ablation fronts to settle the feasibility of dynamic stabilization in the inertial confinement fusion scenario.« less

Design of Launch Vehicle Flight Control Augmentors and Resulting Flight Stability and Control (Center Director's Discretionary Fund Project 93-05, Part III)

NASA Technical Reports Server (NTRS)

Barret, C.

1997-01-01

This publication presents the control requirements, the details of the designed Flight Control Augmentor's (FCA's), the static stability and dynamic stability wind tunnel test programs, the static stability and control analyses, the dynamic stability characteristics of the experimental Launch Vehicle (LV) with the designed FCA's, and a consideration of the elastic vehicle. Dramatic improvements in flight stability have been realized with all the FCA designs; these ranged from 41 percent to 72 percent achieved by the blunt TE design. The control analysis showed that control increased 110 percent with only 3 degrees of FCA deflection. The dynamic stability results showed improvements with all FCA designs tested at all Mach numbers tested. The blunt TE FCA's had the best overall dynamic stability results. Since the lowest elastic vehicle frequency must be well separated from that of the control system, the significant frequencies and modes of vibration have been identified, and the response spectra compared for the experimental LV in both the conventional and the aft cg configuration. Although the dynamic response was 150 percent greater in the aft cg configuration, the lowest bending mode frequency decreased by only 2.8 percent.

Factors Affecting Lateral Stability and Controllability

NASA Technical Reports Server (NTRS)

Campbell, John P; Toll, Thomas A

1948-01-01

The effects on dynamic lateral stability and controllability of some of the important aerodynamic and mass characteristics are discussed and methods are presented for estimating the various stability parameters to be used in the calculation of the dynamic lateral stability of airplanes with swept and low-aspect-ratio wings.

Percutaneous cholecystolithotomy. A minimally invasive alternative to cholecystectomy and to shock wave lithotripsy.

PubMed

Griffith, D P; Gleeson, M J; Appel, M F; Bentlif, P S; Hochman, F L; Toombs, B D; Skolkin, M D

1990-09-01

Recently introduced treatment alternatives for gallstones include peroral pharmacological chemolysis plus shock wave lithotripsy and percutaneous cholecystolithotomy. Herein we report on the treatment preferences of 23 patients with symptomatic gallstones and our initial experience with percutaneous cholecystolithotomy in 6 of these patients. All patients were rendered stone free after one procedure. Percutaneous cholecystolithotomy, which is applicable to all types of gallstones, is a safe, practical, low-morbidity alternative to cholecystectomy in selected patients.

Percutaneous Resection of Renal Urothelial Carcinoma Using Bipolar Electrocautery

PubMed Central

Kwan, Kevin G.; Chew, Ben H.; Luke, Patrick P.W.; Denstedt, John D.

2006-01-01

Percutaneous approaches to upper tract urothelial cancers have been performed in patients unsuitable for radical nephroureterectomy. We present the case of an 82-year-old man with significant comorbidities including dependency on a cardiac pacemaker. Without deactivating the pacemaker, we used bipolar cautery to percutaneously resect a large upper tract urothelial tumor in the renal pelvis. Bipolar cautery is a suitable method of percutaneous or transurethral resection in patients who are pacemaker dependent. PMID:17575777

The importance of steady and dynamic inflow on the stability of rotor-body systems

NASA Technical Reports Server (NTRS)

Peters, David A.

1988-01-01

The induced flow field of a rotor responds in a dynamic fashion to oscillations in rotor lift. This was long known to affect the stability and control derivatives of the rotor. More recently, however, it was also shown that this dynamic inflow also affects rotor and rotor-body aeroelastic stability. Thus, both the steady and unsteady inflow have pronounced effects on air resonance. Recent theoretical developments were made in the modeling of dynamic inflow, and these were verified experimentally. Thus, there is now a simple, verified dynamic inflow model for use in dynamic analyses.

Comparison of two-transsacral-screw fixation versus triangular osteosynthesis for transforaminal sacral fractures.

PubMed

Min, Kyong S; Zamorano, David P; Wahba, George M; Garcia, Ivan; Bhatia, Nitin; Lee, Thay Q

2014-09-01

Transforaminal pelvic fractures are high-energy injuries that are translationally and rotationally unstable. This study compared the biomechanical stability of triangular osteosynthesis vs 2-transsacral-screw fixation in the repair of a transforaminal pelvic fracture model. A transforaminal fracture model was created in 10 cadaveric lumbopelvic specimens. Five of the specimens were stabilized with triangular osteosynthesis, which consisted of unilateral L5-to-ilium lumbopelvic fixation and ipsilateral iliosacral screw fixation. The remaining 5 were stabilized with a 2-transsacral-screw fixation technique that consisted of 2 transsacral screws inserted across S1. All specimens were loaded cyclically and then loaded to failure. Translation and rotation were measured using the MicroScribe 3D digitizing system (Revware Inc, Raleigh, North Carolina). The 2-transsacral-screw group showed significantly greater stiffness than the triangular osteosynthesis group (2-transsacral-screw group, 248.7 N/mm [standard deviation, 73.9]; triangular osteosynthesis group, 125.0 N/mm [standard deviation, 66.9]; P=.02); however, ultimate load and rotational stiffness were not statistically significant. Compared with triangular osteosynthesis fixation, the use of 2 transsacral screws provides a comparable biomechanical stability profile in both translation and rotation. This newly revised 2-transsacral-screw construct offers the traumatologist an alternative method of repair for vertical shear fractures that provides biplanar stability. It also offers the advantage of percutaneous placement in either the prone or supine position. Copyright 2014, SLACK Incorporated.

Efficacy of percutaneous treatment of biliary tract calculi using the holmium:YAG laser.

PubMed

Hazey, J W; McCreary, M; Guy, G; Melvin, W S

2007-07-01

Few Western studies have focused on percutaneous techniques using percutaneous transhepatic choledochoscopy (PTHC) and holmium:yttrium-aluminum-garnet (YAG) laser to ablate biliary calculi in patients unable or unwilling to undergo endoscopic or surgical removal of the calculi. The authors report the efficacy of the holmium:YAG laser in clearing complex biliary calculi using percutaneous access techniques. This study retrospectively reviewed 13 non-Asian patients with complex secondary biliary calculi treated percutaneously using holmium:YAG laser. Percutaneous access was accomplished via left, right, or bilateral hepatic ducts and upsized for passage of a 7-Fr video choledochoscope. Lithotripsy was performed under choledochoscopic vision using a holmium:YAG laser with 200- or 365-microm fibers generating 0.6 to 1.0 joules at 8 to 15 Hz. Patients underwent treatment until stone clearance was confirmed by PTHC. Downsizing and subsequent removal of percutaneous catheters completed the treatment course. Seven men and six women with an average age of 69 years underwent treatment. All the patients had their biliary tract stones cleared successfully. Of the 13 patients, 3 were treated solely as outpatients. The average length of percutaneous access was 108 days. At this writing, one patient still has a catheter in place. The average number of holmium:YAG laser treatments required for stone clearance was 1.6, with no patients requiring more than 3 treatments. Of the 13 patients, 8 underwent a single holmium:YAG laser treatment to clear their calculi. Prior unsuccessful attempts at endoscopic removal of the calculi had been experienced by 7 of the 13 patients. Five patients underwent percutaneous access and subsequent stone removal as their sole therapy for biliary stones. Five patients were cleared of their calculi after percutaneous laser ablation of large stones and percutaneous basket retrieval of the remaining stone fragments. There was one complication of pain requiring admission, and no deaths. The use of PTHC with holmium:YAG laser ablation is safe and efficacious, but requires prolonged biliary access and often multiple procedures to ensure clearance of all calculi.

Antegrade jj stenting after percutaneous renal procedures: The 'pull and push' technique.

PubMed

Ratkal, Jaideep M; Sharma, Elias

2015-06-01

A JJ stent is inserted antegradely after percutaneous renal procedures like percutaneous nephrolithotomy (PCNL) for renal calculus disease, and for endopyelotomy for pelvi-ureteric junction obstruction. We describe a technique for antegrade stent insertion after PCNL.

Management of Complex Cardiac Issues in the Pregnant Patient.

PubMed

Hu, Huayong; Pasca, Ioana

2016-01-01

Management of peripartum heart disease in the intensive care unit requires optimization of maternal hemodynamics and maintenance of fetal perfusion. This requires fetal monitoring and should address the parturient's oxygen saturation, hemoglobin, and cardiac output as it relates to uterine blood flow. Pharmacologic strategies have limited evidence pertaining to hemodynamic stabilization and fetal perfusion. There is some evidence that surgical management of critical mitral stenosis should be percutaneous when possible because cardiac bypass is associated with increased fetal mortality. Fetal monitoring strategies should address central organ perfusion because peripheral scalp pH has not been associated with improved fetal outcomes. Copyright © 2016 Elsevier Inc. All rights reserved.

Evaluation of a Hybrid Dynamic Stabilization and Fusion System in the Lumbar Spine: A 10 Year Experience.

PubMed

Kashkoush, Ahmed; Agarwal, Nitin; Paschel, Erin; Goldschmidt, Ezequiel; Gerszten, Peter C

2016-06-10

The development of adjacent-segment disease is a recognized consequence of lumbar fusion surgery. Posterior dynamic stabilization, or motion preservation, techniques have been developed which theoretically decrease stress on adjacent segments following fusion. This study presents the experience of using a hybrid dynamic stabilization and fusion construct for degenerative lumbar spine pathology in place of rigid arthrodesis. A clinical cohort investigation was conducted of 66 consecutive patients (31 female, 35 male; mean age: 53 years, range: 25 - 76 years) who underwent posterior lumbar instrumentation with the Dynesys Transition Optima (DTO) implant (Zimmer-Biomet Spine, Warsaw, IN) hybrid dynamic stabilization and fusion system over a 10-year period. The median length of follow-up was five years. DTO consists of pedicle screw fixation coupled to a rigid rod as well as a flexible longitudinal connecting system. All patients had symptoms of back pain and neurogenic claudication refractory to non-surgical treatment. Patients underwent lumbar arthrodesis surgery in which the hybrid system was used for stabilization instead of arthrodesis of the stenotic adjacent level. Indications for DTO instrumentation were primary degenerative disc disease (n = 52) and failed back surgery syndrome (n = 14). The most common dynamically stabilized and fused segments were L3-L4 (n = 37) and L5-S1 (n = 33), respectively. Thirty-eight patients (56%) underwent decompression at the dynamically stabilized level, and 57 patients (86%) had an interbody device placed at the level of arthrodesis. Complications during the follow-up period included a single case of screw breakage and a single case of pseudoarthrosis. Ten patients (15%) subsequently underwent conversion of the dynamic stabilization portion of their DTO instrumentation to rigid spinal arthrodesis. The DTO system represents a novel hybrid dynamic stabilization and fusion construct. This 10-year experience found the device to be highly effective as well as safe. The technique may serve as an alternative to multilevel arthrodesis. Implantation of a motion-preserving dynamic stabilization device immediately adjacent to a fused level instead of extending a rigid construct may reduce the subsequent development of adjacent-segment disease in this patient population.

Percutaneous or Open Reduction of Closed Tibial Shaft Fractures During Intramedullary Nailing Does Not Increase Wound Complications, Infection or Nonunion Rates.

PubMed

Auston, Darryl A; Meiss, Jordan; Serrano, Rafael; Sellers, Thomas; Carlson, Gregory; Hoggard, Timothy; Beebe, Michael; Quade, Jonathan; Watson, David; Simpson, Robert Bruce; Kistler, Brian; Shah, Anjan; Sanders, Roy; Mir, Hassan R

2017-04-01

To compare the incidence of complications (wound, infection, and nonunion) among those patients treated with closed, percutaneous, and open intramedullary nailing for closed tibial shaft fractures. Retrospective review. Multiple trauma centers. Skeletally mature patients with closed tibia fractures amenable to treatment with an intramedullary device. Intramedullary fixation with closed, percutaneous, or open reduction. Superficial wound complication, deep infection, nonunion. A total of 317 tibial shaft fractures in 315 patients were included in the study. Two-hundred fractures in 198 patients were treated with closed reduction, 61 fractures in 61 patients were treated with percutaneous reduction, and 56 fractures in 56 patients were treated with formal open reduction. The superficial wound complication rate was 1% (2/200) for the closed group, 1.6% (1/61) for the percutaneous group, and 3.6% (2/56) for the open group with no statistical difference between the groups (P = 0.179). The deep infection rate was 2% (4/200) for the closed group, 1.6% (1/61) for the percutaneous group, and 7.1% (4/56) for the open group with no significant difference between the groups (P = 0.133). Nonunion rate was 5.0% (10/200) for the closed group, 4.9% (3/61) for the percutaneous group, and 7.1% (4/56) for the open group, with no statistical difference between the groups (P = 0.492). This is the largest reported series of closed tibial shaft fractures nailed with percutaneous and open reduction. Percutaneous or open reduction did not result in increased wound complications, infection, or nonunion rates. Carefully performed percutaneous or open approaches can be safely used in obtaining reduction of difficult tibial shaft fractures treated with intramedullary devices. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Effects of percutaneous endoscopic gastrostomy on survival of patients in a persistent vegetative state after stroke.

PubMed

Wu, Kunpeng; Chen, Ying; Yan, Caihong; Huang, Zhijia; Wang, Deming; Gui, Peigen; Bao, Juan

2017-10-01

To assess the effect of percutaneous endoscopic gastrostomy on short- and long-term survival of patients in a persistent vegetative state after stroke and determine the relevant prognostic factors. Stroke may lead to a persistent vegetative state, and the effect of percutaneous endoscopic gastrostomy on survival of stroke patients in a persistent vegetative state remains unclear. Prospective study. A total of 97 stroke patients in a persistent vegetative state hospitalised from January 2009 to December 2011 at the Second Hospital, University of South China, were assessed in this study. Percutaneous endoscopic gastrostomy was performed in 55 patients, and mean follow-up time was 18 months. Survival rate and risk factors were analysed. Median survival in the 55 percutaneous endoscopic gastrostomy-treated patients was 17·6 months, higher compared with 8·2 months obtained for the remaining 42 patients without percutaneous endoscopic gastrostomy treatment. Univariate analyses revealed that age, hospitalisation time, percutaneous endoscopic gastrostomy treatment status, family financial situation, family care, pulmonary infection and nutrition were significantly associated with survival. Multivariate analysis indicated that older age, no gastrostomy, poor family care, pulmonary infection and poor nutritional status were independent risk factors affecting survival. Indeed, percutaneous endoscopic gastrostomy significantly improved the nutritional status and decreased pulmonary infection rate in patients with persistent vegetative state after stroke. Interestingly, median survival time was 20·3 months in patients with no or one independent risk factors of poor prognosis (n = 38), longer compared with 8·7 months found for patients with two or more independent risk factors (n = 59). Percutaneous endoscopic gastrostomy significantly improves long-term survival of stroke patients in a persistent vegetative state and is associated with improved nutritional status and decreased pulmonary infection. Percutaneous endoscopic gastrostomy is a promising option for the management of stroke patients in a persistent vegetative state. © 2016 John Wiley & Sons Ltd.

Logic Dynamics for Deductive Inference -- Its Stability and Neural Basis

NASA Astrophysics Data System (ADS)

Tsuda, Ichiro

2014-12-01

We propose a dynamical model that represents a process of deductive inference. We discuss the stability of logic dynamics and a neural basis for the dynamics. We propose a new concept of descriptive stability, thereby enabling a structure of stable descriptions of mathematical models concerning dynamic phenomena to be clarified. The present theory is based on the wider and deeper thoughts of John S. Nicolis. In particular, it is based on our joint paper on the chaos theory of human short-term memories with a magic number of seven plus or minus two.

A Biomechanical Comparison Of Pin Configurations Used For Percutaneous Pinning Of Distal Tibia Fractures In Children.

PubMed

Brantley, Justin; Majumdar, Aditi; Jobe, J Taylor; Kallur, Antony; Salas, Christina

2016-01-01

Percutaneous pin fixation is often used in conjunction with closed-reduction and cast immobilization to treat pediatric distal tibia fractures. The goal of this procedure is to maintain reduction and provide improved stabilization, in effort to facilitate a more anatomic union. We conducted a biomechanical study of the torsional and bending stability of three commonly used pin configurations in distal tibia fracture fixation. A transverse fracture was simulated at the metaphyseal/diaphyseal junction in 15 synthetic tibias. Each fracture was reduced and fixed with two Kirschner wires, arranged in one of three pin configurations: parallel, retrograde, medial to lateral pins entering at the medial malleolus distal to the fracture (group A); parallel, antegrade, medial to lateral pins entering at the medial diaphysis proximal to the fracture (group B); or a cross-pin configuration with one retrograde, medial to lateral pin entering the medial malleolus distal to the fracture and the second an antegrade, medial to lateral pin entering at the medial diaphysis proximal to the fracture (group C). Stability of each construct was assessed by resistance to torsion and bending. Resistance to external rotation stress was significantly higher in group A than group B (P = 0.044). Resistance to internal rotation stress was significantly higher in group C than group B (P = 0.003). There was no significant difference in torsional stiffness when comparing group A with group C. Under a medial-directed load, group B and C specimens were significantly stiffer than those in group A (28 N/mm and 24 N/mm vs. 14 N/mm for A; P = 0.001 and P = 0.009, respectively). None of the three pin configurations produced superior results with respect to all variables studied. Group A configuration provided the highest resistance to external rotation forces, which is the most clinically relevant variable under short-cast immobilization. Parallel, retrograde, medial to lateral pins entering at the medial malleolus provide the greatest resistance to external rotation of the foot while minimizing the potential for iatrogenic injury to soft tissue structures.

Stability of Markers Used for Real-Time Tumor Tracking After Percutaneous Intrapulmonary Placement

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

Voort van Zyp, Noelle C. van der, E-mail: n.vandervoortvanzyp@erasmusmc.nl; Hoogeman, Mischa S.; Water, Steven van de

2011-11-01

Purpose: To determine the stability of markers used for real-time tumor tracking after percutaneous intrapulmonary placement. Methods and Materials: A total of 42 patients with 44 lesions, 111 markers, and {>=}2 repeat computed tomography (CT) scans were studied. The tumor on the repeat CT scans was registered with the tumor on the planning CT scan. Next, the three-dimensional marker coordinates were determined on the planning CT scan and repeat CT scans. Marker stability was analyzed by the displacement of the markers and the displacement of the center of mass (COM) of the marker configurations. In addition, we assessed the reliabilitymore » of using the intermarker distance as a check for displacements in the COM of the marker configurations. Results: The median marker displacement was 1.3 mm (range, 0.1-53.6). The marker displacement was >5 mm in 12% of the markers and >10 mm in 5% of the markers. The causes of marker displacement >5 mm included marker migration (2 of 13) and target volume changes (5 of 13). Nonsynchronous tumor and marker movement during breathing might have been responsible for the displacements >5 mm in the other 6 of 13 markers. The median displacement in the COM of the marker configurations was 1.0 mm (range, 0.1-23.3). Displacements in the COM of the marker configurations of {>=}2.0 mm were detected by changes in the intermarker distance of >1.5 mm in 96% of the treatment fractions. Conclusion: The median marker displacement was small (1.3 mm). Nevertheless, displacements >5 mm occurred in 12% of the markers. Therefore, we recommend the implantation of multiple markers because multiple markers will enable a quick and reliable check of marker displacement by determining the change in the intermarker distance. A displacement in the COM of the marker configuration of {>=}2.0 mm was almost always detected (96%) by a change in the distance between the markers of >1.5 mm. This enabled the displaced marker to be disabled, such that tumor localization was not compromised.« less

Major Bleeding after Percutaneous Image-Guided Biopsies: Frequency, Predictors, and Periprocedural Management

PubMed Central

Kennedy, Sean A.; Milovanovic, Lazar; Midia, Mehran

2015-01-01

Major bleeding remains an uncommon yet potentially devastating complication following percutaneous image-guided biopsy. This article reviews two cases of major bleeding after percutaneous biopsy and discusses the frequency, predictors, and periprocedural management of major postprocedural bleeding. PMID:25762845

21 CFR 870.1250 - Percutaneous catheter.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Percutaneous catheter. 870.1250 Section 870.1250 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Diagnostic Devices § 870.1250 Percutaneous catheter...

21 CFR 870.1250 - Percutaneous catheter.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Percutaneous catheter. 870.1250 Section 870.1250 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Diagnostic Devices § 870.1250 Percutaneous catheter...

Antegrade jj stenting after percutaneous renal procedures: The ‘pull and push’ technique

PubMed Central

Ratkal, Jaideep M.; Sharma, Elias

2014-01-01

A JJ stent is inserted antegradely after percutaneous renal procedures like percutaneous nephrolithotomy (PCNL) for renal calculus disease, and for endopyelotomy for pelvi-ureteric junction obstruction. We describe a technique for antegrade stent insertion after PCNL. PMID:26413327

The need for higher-order averaging in the stability analysis of hovering, flapping-wing flight.

PubMed

Taha, Haithem E; Tahmasian, Sevak; Woolsey, Craig A; Nayfeh, Ali H; Hajj, Muhammad R

2015-01-05

Because of the relatively high flapping frequency associated with hovering insects and flapping wing micro-air vehicles (FWMAVs), dynamic stability analysis typically involves direct averaging of the time-periodic dynamics over a flapping cycle. However, direct application of the averaging theorem may lead to false conclusions about the dynamics and stability of hovering insects and FWMAVs. Higher-order averaging techniques may be needed to understand the dynamics of flapping wing flight and to analyze its stability. We use second-order averaging to analyze the hovering dynamics of five insects in response to high-amplitude, high-frequency, periodic wing motion. We discuss the applicability of direct averaging versus second-order averaging for these insects.

Radial scars without atypia in percutaneous biopsy specimens: can they obviate surgical biopsy?

PubMed

Mesa-Quesada, J; Romero-Martín, S; Cara-García, M; Martínez-López, A; Medina-Pérez, M; Raya-Povedano, J L

To evaluate the need for surgical biopsy in patients diagnosed with radial scars without atypia by percutaneous biopsy. In this retrospective observational study, we selected patients with a histological diagnosis of radial scar in specimens obtained by percutaneous biopsy during an 8-year period. The statistical analysis was centered on patients with radial scar without atypia (we assessed the radiologic presentation, the results of the percutaneous biopsy, and their correlation with the results of surgical biopsy and follow-up) and we added the patients with atypia and cancer in the elaboration of the diagnostic indices. We identified 96 patients with radial scar on percutaneous biopsy; 54 had no atypia, 18 had atypia, and 24 had cancer. Among patients with radial scar without atypia, there were no statistically significant differences between patients who underwent imaging follow-up and those who underwent surgical biopsy (p>0.05). The rate of underdiagnosis for percutaneous biopsy in patients without atypia was 1.9%. The rates of diagnosis obtained with percutaneous biopsy in relation to follow-up and surgical biopsy in the 96 cases were sensitivity 92.3%, specificity 100%, positive predictive value 100%, negative predictive value 97.2%, and accuracy 97.9%. The area under the ROC curve was 0.96 (p<0.001), and the kappa concordance index was 0.95 (p<0.001) CONCLUSIONS: We consider that it is not necessary to perform surgical biopsies in patients with radial scars without atypia on percutaneous biopsies because the rate of underestimation is very low and the concordance between the diagnosis reached by percutaneous biopsy and the definitive diagnosis is very high. Copyright © 2017 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

Training for percutaneous renal access on a virtual reality simulator.

PubMed

Zhang, Yi; Yu, Cheng-fan; Liu, Jin-shun; Wang, Gang; Zhu, He; Na, Yan-qun

2013-01-01

The need to develop new methods of surgical training combined with advances in computing has led to the development of virtual reality surgical simulators. The PERC Mentor(TM) is designed to train the user in percutaneous renal collecting system access puncture. This study aimed to validate the use of this kind of simulator, in percutaneous renal access training. Twenty-one urologists were enrolled as trainees to learn a fluoroscopy-guided percutaneous renal accessing technique. An assigned percutaneous renal access procedure was immediately performed on the PERC Mentor(TM) after watching instruction video and an analog operation. Objective parameters were recorded by the simulator and subjective global rating scale (GRS) score were determined. Simulation training followed and consisted of 2 hours daily training sessions for 2 consecutive days. Twenty-four hours after the training session, trainees were evaluated performing the same procedure. The post-training evaluation was compared to the evaluation of the initial attempt. During the initial attempt, none of the trainees could complete the appointed procedure due to the lack of experience in fluoroscopy-guided percutaneous renal access. After the short-term training, all trainees were able to independently complete the procedure. Of the 21 trainees, 10 had primitive experience in ultrasound-guided percutaneous nephrolithotomy. Trainees were thus categorized into the group of primitive experience and inexperience. The total operating time and amount of contrast material used were significantly lower in the group of primitive experience versus the inexperience group (P = 0.03 and 0.02, respectively). The training on the virtual reality simulator, PERC Mentor(TM), can help trainees with no previous experience of fluoroscopy-guided percutaneous renal access to complete the virtual manipulation of the procedure independently. This virtual reality simulator may become an important training and evaluation tool in teaching fluoroscopy-guided percutaneous renal access.

Static and dynamic stability analysis of the space shuttle vehicle-orbiter

NASA Technical Reports Server (NTRS)

Chyu, W. J.; Cavin, R. K.; Erickson, L. L.

1978-01-01

The longitudinal static and dynamic stability of a Space Shuttle Vehicle-Orbiter (SSV Orbiter) model is analyzed using the FLEXSTAB computer program. Nonlinear effects are accounted for by application of a correction technique in the FLEXSTAB system; the technique incorporates experimental force and pressure data into the linear aerodynamic theory. A flexible Orbiter model is treated in the static stability analysis for the flight conditions of Mach number 0.9 for rectilinear flight (1 g) and for a pull-up maneuver (2.5 g) at an altitude of 15.24 km. Static stability parameters and structural deformations of the Orbiter are calculated at trim conditions for the dynamic stability analysis, and the characteristics of damping in pitch are investigated for a Mach number range of 0.3 to 1.2. The calculated results for both the static and dynamic stabilities are compared with the available experimental data.

Decomposition-aggregation stability analysis. [for large scale dynamic systems with application to spinning Skylab control system

NASA Technical Reports Server (NTRS)

Siljak, D. D.; Weissenberger, S.; Cuk, S. M.

1973-01-01

This report presents the development and description of the decomposition aggregation approach to stability investigations of high dimension mathematical models of dynamic systems. The high dimension vector differential equation describing a large dynamic system is decomposed into a number of lower dimension vector differential equations which represent interconnected subsystems. Then a method is described by which the stability properties of each subsystem are aggregated into a single vector Liapunov function, representing the aggregate system model, consisting of subsystem Liapunov functions as components. A linear vector differential inequality is then formed in terms of the vector Liapunov function. The matrix of the model, which reflects the stability properties of the subsystems and the nature of their interconnections, is analyzed to conclude over-all system stability characteristics. The technique is applied in detail to investigate the stability characteristics of a dynamic model of a hypothetical spinning Skylab.

Percutaneous Retrieval of Misplaced Intravascular Foreign Objects with the Dormia Basket: An Effective Solution

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

Sheth, Rahul; Someshwar, Vimal; Warawdekar, Gireesh

2007-02-15

Purpose. We report our experience of the retrieval of intravascular foreign body objects by the percutaneous use of the Gemini Dormia basket. Methods. Over a period of 2 years we attempted the percutaneous removal of intravascular foreign bodies in 26 patients. Twenty-six foreign bodies were removed: 8 intravascular stents, 4 embolization coils, 9 guidewires, 1 pacemaker lead, and 4 catheter fragments. The percutaneous retrieval was achieved with a combination of guide catheters and the Gemini Dormia basket. Results. Percutaneous retrieval was successful in 25 of 26 patients (96.2%). It was possible to remove all the intravascular foreign bodies with amore » combination of guide catheters and the Dormia basket. No complication occurred during the procedure, and no long-term complications were registered during the follow-up period, which ranged from 6 months to 32 months (mean 22.4 months overall). Conclusion. Percutaneous retrieval is an effective and safe technique that should be the first choice for removal of an intravascular foreign body.« less

Percutaneous absorption of several chemicals, some pesticides included, in the red-winged blackbird

USGS Publications Warehouse

Rogers, J.G.; Cagan, R.H.; Kare, M.R.

1974-01-01

Percutaneous absorption in vivo through the skin of the feet of the red-winged blackbird (Agelaius phoeniceus) has been investigated. Absorption after 18-24 hours exposure to 0.01 M solutions of salicylic acid, caffeine, urea, 2,4-D, dieldrin, diethylstilbesterol, and DDT was measured. Of these, only DDT and diethylstilbesterol were not absorbed to a measurable degree. The solvents ethanol, dimethylsulfoxide (DMSO), and vegetable oil were compared with water in their effects on the absorption ofcaffeine, urea, and salicylic acid. Ethanol, DMSO,and oil each decreased percutaneous absorption of salicylic acid. DMSO increased absorption of caffeine, and ethanol had no effect on it. Neither DMSO nor ethanol affected penetration of urea. Partition coefficients (K) (epidermis/water) were determined for all seven penetrants. Compounds with higher values of K showed lower percutaneous absorption. These findings suggest that K may be useful to predict percutaneous absorption in vivo. It appears unlikely that percutaneous absorption contributes greatly to the body burden of 2,4-D and dieldrin in A. phoeniceus.

Seven-year follow-up of percutaneous closure of patent foramen ovale.

PubMed

Mirzada, Naqibullah; Ladenvall, Per; Hansson, Per-Olof; Johansson, Magnus Carl; Furenäs, Eva; Eriksson, Peter; Dellborg, Mikael

2013-12-01

Observational studies favor percutaneous closure of patent foramen ovale (PFO) over medical treatment to reduce recurrent stroke while randomized trials fail to demonstrate significant superiority of percutaneous PFO closure. Few long-term studies are available post PFO closure. This study reports long-term clinical outcomes after percutaneous PFO closure. Between 1997 and 2006, 86 consecutive eligible patients with cerebrovascular events, presumably related to PFO, underwent percutaneous PFO closure. All 86 patients were invited to a long-term follow-up, which was carried out during 2011 and 2012. Percutaneous PFO closure was successfully performed in 85 of 86 patients. The follow-up rate was 100%. No cardiovascular or cerebrovascular deaths occurred. Two patients (both women) died from lung cancer during follow-up. Follow-up visits were conducted for 64 patients and the remaining 20 patients were followed up by phone. The mean follow-up time was 7.3 years (5 to 12.4 years). Mean age at PFO closure was 49 years. One patient had a minor stroke one month after PFO closure and a transient ischemic attack (TIA) two years afterwards. One other patient suffered from a TIA six years after closure. No long-term device-related complications were observed. Percutaneous PFO closure was associated with very low risk of recurrent stroke and is suitable in most patients. We observed no mortality and no long-term device-related complications related to PFO closure, indicating that percutaneous PFO closure is a safe and efficient treatment even in the long term.

Salvage Percutaneous Vertebral Augmentation Using Polymethyl Methacrylate in Patients with Failed Interbody Fusion.

PubMed

Yun, Dong-Ju; Hwang, Byeong-Wook; Oh, Hyeong-Seok; Kim, Jin-Sung; Jeon, Sang-Hyeop; Lee, Sang-Ho

2016-11-01

Percutaneous vertebral augmentation with cement is used as a salvage procedure for failed instrumentation. Few studies have reported the use of this procedure for failed anterior lumbar fusion in elderly patients with osteoporosis and other complicated diseases who have undergone a previous major operation. Between January 2007 and December 2015, the clinical and radiographic results of 8 patients with osteoporosis who showed subsidence and migration of the implant after an initial operation were examined. After the development of implant failure, the patients underwent vertebral augmentation with polymethyl methacrylate. Mean patient age was 73.4 years (range, 67-78 years), and mean bone mineral density was -2.96 (range, -2.1 to -3.8). The mean radiologic follow-up period between augmentation and the last follow-up examination was 16 months (range, 3-38 months). Although the subjective clinical outcome was not satisfying to the patients, no loss of correction, fractures, or screw loosening occurred during the follow-up period. The injection of cement around the instrument might help to stabilize it by providing strength to the axis and preventing further loosening. This salvage procedure could be an alternative in the management of cases with failed interbody fusion. Copyright © 2016 Elsevier Inc. All rights reserved.

Influence of percutaneous mitral valve repair using the MitraClip® system on renal function in patients with severe mitral regurgitation.

PubMed

Rassaf, Tienush; Balzer, Jan; Rammos, Christos; Zeus, Tobias; Hellhammer, Katharina; v Hall, Silke; Wagstaff, Rabea; Kelm, Malte

2015-04-01

In patients with mitral regurgitation (MR), changes in cardiac stroke volume, and thus renal preload and afterload may affect kidney function. Percutaneous mitral valve repair (PMVR) with the MitraClip® system can be a therapeutic alternative to surgical valve repair. The influence of MitraClip® therapy on renal function and clinical outcome parameters is unknown. Sixty patients with severe MR underwent PMVR using the MitraClip® system in an open-label observational study. Patients were stratified according to their renal function. All clips have been implanted successfully. Effective reduction of MR by 2-3 grades acutely improved KDOQI class. Lesser MR reduction (MR reduction of 0-1 grades) led to worsening of renal function in patients with pre-existing normal or mild (KDOQI 1-2) compared to severe (KDOQI 3-4) renal dysfunction. Reduction of MR was associated with improvement in Minnesota Living with Heart Failure Questionnaire (MLHFQ), NYHA-stadium, and 6-minute walk test. Successful PMVR was associated with an improvement in renal function. The improvement in renal function was associated with the extent of MR reduction and pre-existing kidney dysfunction. Our data emphasize the relevance of PVMR to stabilize the cardiorenal axis in patients with severe MR. © 2014 Wiley Periodicals, Inc.

Dynamic stabilization of an optomechanical oscillator

DTIC Science & Technology

2014-10-20

respectively. The proper frequency of the pendulum is ω0 = √ g/, where g is the gravitational acceleration and is the length of the pendulum . The...controlled experiments. In this paper we discuss one such situation, the dynamic stabilization of a mechanical system such as an inverted pendulum . The...quantumoptomechanics, macroscopic quantum system, dynamic stabilization, Kapitza pendulum REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S

Standard representation and unified stability analysis for dynamic artificial neural network models.

PubMed

Kim, Kwang-Ki K; Patrón, Ernesto Ríos; Braatz, Richard D

2018-02-01

An overview is provided of dynamic artificial neural network models (DANNs) for nonlinear dynamical system identification and control problems, and convex stability conditions are proposed that are less conservative than past results. The three most popular classes of dynamic artificial neural network models are described, with their mathematical representations and architectures followed by transformations based on their block diagrams that are convenient for stability and performance analyses. Classes of nonlinear dynamical systems that are universally approximated by such models are characterized, which include rigorous upper bounds on the approximation errors. A unified framework and linear matrix inequality-based stability conditions are described for different classes of dynamic artificial neural network models that take additional information into account such as local slope restrictions and whether the nonlinearities within the DANNs are odd. A theoretical example shows reduced conservatism obtained by the conditions. Copyright © 2017. Published by Elsevier Ltd.

The influence of dental unit design on percutaneous injury.

PubMed

Harte, J; Davis, R; Plamondon, T; Richardson, B

1998-12-01

The handpiece receptacle of a European, buggy-whip-style dental unit is in a different location than that of a conventional dental unit. This study investigated whether this difference affects the incidence of percutaneous injuries among dental professionals. The researchers asked dental professionals to record descriptions of percutaneous injuries they sustained during a period of 30 workdays. Findings indicated that most injuries were bur-related and that there was no statistically significant difference between the European and the conventional dental units with respect to the incidence of percutaneous injury.

Shaving effects on percutaneous penetration: clinical implications.

PubMed

Hamza, Muhammad; Tohid, Hassaan; Maibach, Howard

2015-01-01

Human/animal shaving biology. To assess the effect of shaving on percutaneous penetration and skin function. We screened 500+publications in Pub Med, Scopus, Cochrane Library and pertinent journals out of which only 17 were deemed relevant. Terms for searches included shaving and skin, percutaneous penetration and shaving, skin absorption and shaving, absorption of dyes and shaving, skin penetration, effects of shaving and absorption, shave and dyes, axillary shaving and stratum corneum, shaving and breast cancer, shaving and infections, etc. Shaving appears to have an exaggerated effect on percutaneous absorption; however, some studies do not support this evidence. Shaving enhances percutaneous penetration of some chemicals; however this effect is species and chemical specific. Further investigations of chemicals of varying physio-chemical properties are mandated before a generalized theory can be promulgated.

Narrowing the gap: early and intermediate outcomes after percutaneous coronary intervention and coronary artery bypass graft procedures in California, 1997 to 2006.

PubMed

Carey, Joseph S; Danielsen, Beate; Milliken, Jeffrey; Li, Zhongmin; Stabile, Bruce E

2009-11-01

Percutaneous coronary intervention is increasingly used to treat multivessel coronary artery disease. Coronary artery bypass graft procedures have decreased, and as a result, percutaneous coronary intervention has increased. The overall impact of this treatment shift is uncertain. We examined the in-hospital mortality and complication rates for these procedures in California using a combined risk model. The confidential dataset of the Office of Statewide Health Planning and Development patient discharge database was queried for 1997 to 2006. A risk model was developed using International Classification of Diseases, Ninth Revision, Clinical Modification procedures and diagnostic codes from the combined pool of isolated coronary artery bypass graft and percutaneous coronary intervention procedures performed during 2005 and 2006. In-hospital mortality was corrected for "same-day" transfers to another health care institution. Early failure rate was defined as in-hospital mortality rate plus reintervention for another percutaneous coronary intervention or cardiac surgery procedure within 90 days. Coronary artery bypass graft volume decreased from 28,495 (1997) to 15,520 (2006), whereas percutaneous coronary intervention volume increased from 38,098 to 53,703. Risk-adjusted mortality rate decreased from 4.7% to 2.1% for coronary artery bypass graft procedures and from 3.4% to 1.9% for percutaneous coronary intervention. Expected mortality rate increased for both procedures. Early failure rate decreased from 13.1% to 8.0% for percutaneous coronary intervention and from 6.5% to 5.4% for coronary artery bypass graft. For the years 2004 and 2005, the risk of recurrent myocardial infarction or need for coronary artery bypass graft during the first postoperative year was 12% for percutaneous coronary intervention and 6% for coronary artery bypass grafts. This study shows that as volume shifted from coronary artery bypass grafts to percutaneous coronary intervention, expected mortality increased for both procedures. Risk-adjusted mortality rate decreased for both procedures, more so for coronary artery bypass grafts, so that corrected in-hospital mortality rates essentially equalized at approximately 2.0% in 2006. The post-procedural risk of reintervention, death, or myocardial infarction within the first year was twice as high for percutaneous coronary intervention as for coronary artery bypass grafts.

Lateral Stability of a Dynamic Ram Air Cushion Vehicle

DOT National Transportation Integrated Search

1974-08-01

The lateral stability derivatives of a dynamic ram air cushion vehicle in a rectangular guideway were measured using a ship model towing tank. Lift and pitching moment are also reported. The primary lateral derivatives are all stabilizing, with signi...

Stabilization of dynamics of oscillatory systems by nonautonomous perturbation.

PubMed

Lucas, Maxime; Newman, Julian; Stefanovska, Aneta

2018-04-01

Synchronization and stability under periodic oscillatory driving are well understood, but little is known about the effects of aperiodic driving, despite its abundance in nature. Here, we consider oscillators subject to driving with slowly varying frequency, and investigate both short-term and long-term stability properties. For a phase oscillator, we find that, counterintuitively, such variation is guaranteed to enlarge the Arnold tongue in parameter space. Using analytical and numerical methods that provide information on time-variable dynamical properties, we find that the growth of the Arnold tongue is specifically due to the growth of a region of intermittent synchronization where trajectories alternate between short-term stability and short-term neutral stability, giving rise to stability on average. We also present examples of higher-dimensional nonlinear oscillators where a similar stabilization phenomenon is numerically observed. Our findings help support the case that in general, deterministic nonautonomous perturbation is a very good candidate for stabilizing complex dynamics.

Stabilization of dynamics of oscillatory systems by nonautonomous perturbation

NASA Astrophysics Data System (ADS)

Lucas, Maxime; Newman, Julian; Stefanovska, Aneta

2018-04-01

Synchronization and stability under periodic oscillatory driving are well understood, but little is known about the effects of aperiodic driving, despite its abundance in nature. Here, we consider oscillators subject to driving with slowly varying frequency, and investigate both short-term and long-term stability properties. For a phase oscillator, we find that, counterintuitively, such variation is guaranteed to enlarge the Arnold tongue in parameter space. Using analytical and numerical methods that provide information on time-variable dynamical properties, we find that the growth of the Arnold tongue is specifically due to the growth of a region of intermittent synchronization where trajectories alternate between short-term stability and short-term neutral stability, giving rise to stability on average. We also present examples of higher-dimensional nonlinear oscillators where a similar stabilization phenomenon is numerically observed. Our findings help support the case that in general, deterministic nonautonomous perturbation is a very good candidate for stabilizing complex dynamics.

Molecular dynamics study of thermodynamic stability and dynamics of [Li(glyme)]+ complex in lithium-glyme solvate ionic liquids

NASA Astrophysics Data System (ADS)

Shinoda, Wataru; Hatanaka, Yuta; Hirakawa, Masashi; Okazaki, Susumu; Tsuzuki, Seiji; Ueno, Kazuhide; Watanabe, Masayoshi

2018-05-01

Equimolar mixtures of glymes and organic lithium salts are known to produce solvate ionic liquids, in which the stability of the [Li(glyme)]+ complex plays an important role in determining the ionic dynamics. Since these mixtures have attractive physicochemical properties for application as electrolytes, it is important to understand the dependence of the stability of the [Li(glyme)]+ complex on the ion dynamics. A series of microsecond molecular dynamics simulations has been conducted to investigate the dynamic properties of these solvate ionic liquids. Successful solvate ionic liquids with high stability of the [Li(glyme)]+ complex have been shown to have enhanced ion dynamics. Li-glyme pair exchange rarely occurs: its characteristic time is longer than that of ion diffusion by one or two orders of magnitude. Li-glyme pair exchange most likely occurs through cluster formation involving multiple [Li(glyme)]+ pairs. In this process, multiple exchanges likely take place in a concerted manner without the production of energetically unfavorable free glyme or free Li+ ions.

Emergency percutaneous nephrostomy versus emergency percutaneous nephrolithotomy in patients with sepsis associated with large uretero-pelvic junction stone impaction: a randomized controlled trial.

PubMed

Hsu, Chi-Sen; Wang, Chung-Jing; Chang, Chien-Hsing; Tsai, Po-Chao; Chen, Hung-Wen; Su, Yi-Chun

2017-01-01

A randomized trial was conducted prospectively to evaluate the efficacy, related complications, and convalescence of emergency percutaneous nephrolithotomy compared to percutaneous nephrostomy for decompression of the collecting system in cases of sepsis associated with large uretero-pelvic junction stone impaction. The inclusion criteria included a WBC count of 10.000/mm3 or more and/or a temperature of 38°C or higher. Besides, all enrolled patients should maintain stable hemodynamic status and proper organ perfusions. A total of 113 patients with large, obstructive uretero-pelvic junction stones and clinical signs of sepsis completed the study protocol. Of those, 56 patients were placed in the emergency percutaneous nephrostomy group, while the other 57 patients were part of the percutaneous nephrolithotomy group. The primary end point was the time until normalization of white blood cells (WBC) at a count of 10.000/mm3 or less, and a temperature of 37.4°C or lower. The secondary end points included the comparison of analgesic consumption, length of stay, and related complications. Statistical analysis was performed using SPSS® version 14.0.1. The Mann-Whitney U test, chi-square test, and Fisher's exact test were used as appropriate. The length of hospital stays (in days) was 10.09±3.43 for the emergency percutaneous nephrostomy group and 8.18±2.72 for the percutaneous nephrolithotomy group. This set of data noted a significant difference between groups. There was no difference between groups in regard to white blood cell count (in mm3), time to normalization of white blood cell count (in days), body temperature (in ºC), time to normalization of body temperature (in days), C-reactive proteins (in mg/dL), time taken for C-reactive proteins to decrease over 25% (in days), procalcitonin (in ng/mL), or complication rates. This study confirms that emergency percutaneous nephrolithotomy may be as safe as early percutaneous nephrolithotomy in a selected low risk patients with sepsis-associated large, obstructive stone. Copyright® by the International Brazilian Journal of Urology.

Dynamics of a distributed drill string system: Characteristic parameters and stability maps

NASA Astrophysics Data System (ADS)

Aarsnes, Ulf Jakob F.; van de Wouw, Nathan

2018-03-01

This paper involves the dynamic (stability) analysis of distributed drill-string systems. A minimal set of parameters characterizing the linearized, axial-torsional dynamics of a distributed drill string coupled through the bit-rock interaction is derived. This is found to correspond to five parameters for a simple drill string and eight parameters for a two-sectioned drill-string (e.g., corresponding to the pipe and collar sections of a drilling system). These dynamic characterizations are used to plot the inverse gain margin of the system, parametrized in the non-dimensional parameters, effectively creating a stability map covering the full range of realistic physical parameters. This analysis reveals a complex spectrum of dynamics not evident in stability analysis with lumped models, thus indicating the importance of analysis using distributed models. Moreover, it reveals trends concerning stability properties depending on key system parameters useful in the context of system and control design aiming at the mitigation of vibrations.

Biomechanical assessment of dynamic balance: Specificity of different balance tests.

PubMed

Ringhof, Steffen; Stein, Thorsten

2018-04-01

Dynamic balance is vitally important for most sports and activities of daily living, so the assessment of dynamic stability has become an important issue. In consequence, a large number of balance tests have been developed. However, it is not yet known whether these tests (i) measure the same construct and (ii) can differentiate between athletes with different balance expertise. We therefore studied three common dynamic balance tests: one-leg jump landings, Posturomed perturbations and simulated forward falls. Participants were 24 healthy young females in regular training in either gymnastics (n = 12) or swimming (n = 12). In each of the tests, the participants were instructed to recover balance as quickly as possible. Dynamic stability was computed by time to stabilization and margin of stability, deduced from force plates and motion capture respectively. Pearson's correlations between the dynamic balance tests found no significant associations between the respective dynamic stability measures. Furthermore, independent t-tests indicated that only jump landings could properly distinguish between both groups of athletes. In essence, the different dynamic balance tests applied did not measure the same construct but rather task-specific skills, each of which depends on multifactorial internal and external constraints. Our study therefore contradicts the traditional view of considering balance as a general ability, and reinforces that dynamic balance measures are not interchangeable. This highlights the importance of selecting appropriate balance tests. Copyright © 2018 Elsevier B.V. All rights reserved.

A pilot study of the validation of percutaneous testing in cats.

PubMed

Rossi, Michael A; Messinger, Linda; Olivry, Thierry; Hoontrakoon, Raweewan

2013-10-01

Intradermal testing is useful for the identification of environmental allergens to which cats could be hypersensitive; intradermal test reactions are often subtle and difficult to interpret in cats. Percutaneous testing is the standard technique for the detection of significant environmental allergens in people, but it has not yet been evaluated in cats with hypersensitivity dermatitis. The purpose of this study was to evaluate and compare the skin test responses of healthy cats to percutaneous application and intradermal injections of control solutions. Ten clinically healthy cats were studied. Percutaneous applications of 0.0275 and 0.1 mg/mL aqueous histamine, 6 mg/mL glycerinated histamine, 0.9% buffered saline and 50% glycerosaline solution were performed using Greer Pick (Greer Laboratories, Lenoir, NC, USA) and Duotip-Test II (Lincoln Diagnostics, Decatur, IL, USA) percutaneous applicators. Reactions were compared with intradermal injections of 0.0275 mg/mL aqueous histamine and 0.9% buffered saline as controls. Positive responses to histamine solutions were significantly greater with the Greer Pick than with the Duotip-Test II. There were no significant differences between the histamine reactions using the Greer Pick applicator and the intradermal injections. Percutaneous reactions to histamine were more well demarcated and easier to read than intradermal injection reactions. Reactions to the saline controls were not noted. Percutaneous application of 6 mg/mL glycerinated histamine solution, 50% glycerosaline solution and 0.9% buffered saline produced similar positive and negative control wheals. These observations warrant further studies of percutaneous allergen testing in cats with hypersensitivity dermatitis. © 2013 ESVD and ACVD.

The Role of Percutaneous Biopsy and Prognostic Factors of Malignancy in Solitary Breast Papilloma: A Retrospective Multicenter Study of 259 Cases.

PubMed

Laval, Maude; Delangle, Romain; Ndoye, Aïcha; Sylvestre, Emmanuelle; Laviolle, Bruno; Lavoue, Vincent; Levêque, Jean

2015-12-01

Management of papillary breast lesions is a controversial issue, as complete excision implies surgery of numerous benign lesions. The purpose of this study was to assess concordance between percutaneous and surgical biopsy of papillomas along with factors predictive of malignancy. The study consisted of a retrospective review of papilloma cases between 2009 and 2013 at three breast cancer centers. All cases of papilloma histologically diagnosed by percutaneous biopsy and confirmed by surgical specimen were included. The biopsy results were compared with final surgical pathology. Lesion size and clinical and radiological features were recorded. A total of 259 cases were included (188 simple and 71 complex papillomas). Concordance between histology after percutaneous and surgical biopsy was lower for complex papillomas, regardless of type, than for simple papillomas (p<0.001). The risk of having a complex papilloma was shown to be significantly higher in postmenopausal patients (p=0.023), and was 20 times higher if the percutaneous biopsy was malignant as opposed to benign (p<2.10). However, the false-negatives for percutaneous biopsy in complex papilloma cases were mainly related to atypical and in situ lesions. Percutaneous biopsy does not appear adequate for identifying papillomas requiring surgical excision due to the risk of underestimation of cancerous lesions. However, certain factors predictive of malignancy may assist with surgical management, such as age and menopausal status, lesions peripheral to the nipple, and atypia on percutaneous biopsy. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Combined analytical and numerical approaches in Dynamic Stability analyses of engineering systems

NASA Astrophysics Data System (ADS)

Náprstek, Jiří

2015-03-01

Dynamic Stability is a widely studied area that has attracted many researchers from various disciplines. Although Dynamic Stability is usually associated with mechanics, theoretical physics or other natural and technical disciplines, it is also relevant to social, economic, and philosophical areas of our lives. Therefore, it is useful to occasionally highlight the general aspects of this amazing area, to present some relevant examples and to evaluate its position among the various branches of Rational Mechanics. From this perspective, the aim of this study is to present a brief review concerning the Dynamic Stability problem, its basic definitions and principles, important phenomena, research motivations and applications in engineering. The relationships with relevant systems that are prone to stability loss (encountered in other areas such as physics, other natural sciences and engineering) are also noted. The theoretical background, which is applicable to many disciplines, is presented. In this paper, the most frequently used Dynamic Stability analysis methods are presented in relation to individual dynamic systems that are widely discussed in various engineering branches. In particular, the Lyapunov function and exponent procedures, Routh-Hurwitz, Liénard, and other theorems are outlined together with demonstrations. The possibilities for analytical and numerical procedures are mentioned together with possible feedback from experimental research and testing. The strengths and shortcomings of these approaches are evaluated together with examples of their effective complementing of each other. The systems that are widely encountered in engineering are presented in the form of mathematical models. The analyses of their Dynamic Stability and post-critical behaviour are also presented. The stability limits, bifurcation points, quasi-periodic response processes and chaotic regimes are discussed. The limit cycle existence and stability are examined together with their separating roles as attractors and repulsers. Two levels of stability loss (recovery of the system is possible or final collapse is inevitable) as can be observed in softening systems are noted. Time-limited excitation and relevant transition effects (e.g., seismic excitation) are also discussed, together with the evaluation of possible system reliability improvement. The Dynamic Stability investigation of two degrees-of-freedom aero-elastic systems in a linear formulation using several approaches is briefly highlighted. Further systems modelling problems that arise in transport engineering are also outlined. A few hints for applications are given. Some open problems and possible future research strategies are outlined.

The Discriminant Value of Phase-Dependent Local Dynamic Stability of Daily Life Walking in Older Adult Community-Dwelling Fallers and Nonfallers

PubMed Central

Ihlen, Espen A. F.; Weiss, Aner; Helbostad, Jorunn L.; Hausdorff, Jeffrey M.

2015-01-01

The present study compares phase-dependent measures of local dynamic stability of daily life walking with 35 conventional gait features in their ability to discriminate between community-dwelling older fallers and nonfallers. The study reanalyzes 3D-acceleration data of 3-day daily life activity from 39 older people who reported less than 2 falls during one year and 31 who reported two or more falls. Phase-dependent local dynamic stability was defined for initial perturbation at 0%, 20%, 40%, 60%, and 80% of the step cycle. A partial least square discriminant analysis (PLS-DA) was used to compare the discriminant abilities of phase-dependent local dynamic stability with the discriminant abilities of 35 conventional gait features. The phase-dependent local dynamic stability λ at 0% and 60% of the step cycle discriminated well between fallers and nonfallers (AUC = 0.83) and was significantly larger (p < 0.01) for the nonfallers. Furthermore, phase-dependent λ discriminated as well between fallers and nonfallers as all other gait features combined. The present result suggests that phase-dependent measures of local dynamic stability of daily life walking might be of importance for further development in early fall risk screening tools. PMID:26491669

Dynamic postural stability for double-leg drop landing.

PubMed

Niu, Wenxin; Zhang, Ming; Fan, Yubo; Zhao, Qinping

2013-01-01

Dynamic postural stability has been widely studied for single-leg landing, but seldom considered for double-leg landing. This study aimed to evaluate the dynamic postural stability and the influence mechanism of muscle activities during double-leg drop landing. Eight recreationally active males and eight recreationally active females participated in this study and dropped individually from three heights (0.32 m, 0.52 m, and 0.72 m). Ground reaction force was recorded to calculate the time to stabilisation. Electromyographic activities were recorded for selected lower-extremity muscles. A multivariate analysis of variance was carried out and no significant influence was found in time to stabilisation between genders or limb laterals (P > 0.05). With increasing drop height, time to stabilisation decreased significantly in two horizontal directions and the lower-extremity muscle activities were enhanced. Vertical time to stabilisation was not significantly influenced by drop height. Dynamic postural stability improved by neuromuscular change more than that required due to the increase of drop height. Double-leg landing on level ground is a stable movement, and the body would often be injured before dynamic postural stability is impaired. It is understandable to protect tissues from mechanical injuries by the sacrifice of certain dynamic postural stability in the design of protective devices or athlete training.

Percutaneous closure of patent arterial ducts in patients from high altitude: a sub-Saharan experience.

PubMed

Tefera, Endale; Qureshi, Shakeel A; Bermudez-Cañete, Ramòn; Rubio, Lola

2015-01-01

At high altitude, patent arterial ducts tend to be larger and associated with pulmonary hypertension. Patent ductus arteriosus device closure in this background could be challenging. We report our experience with percutaneous closure of patent arterial ducts using a variety of devices in patients residing in a high altitude. This is a retrospective review of the case records of 145 patients (age 9 months-20 years, mean 5.6 ± 3.9 years, and weight 7-54 kg, mean 17.7 ± 9.4) with duct sizes ranging between 2 and 21 mm, (mean, 5.8 ± 2.7) who underwent percutaneous closure of patent arterial ducts. One hundred thirty-six (93.8%) of the patients were from a geographic area of 2100-2800 m above sea level. Successful device closure was achieved in 143 cases. It was difficult to achieve device stability in two patients with expansile ducts. Therefore, they were treated surgically. The devices used were various types of duct occluder devices in 131 patients, while atrial and ventricular septal occluders were used in eight patients. For the group, mean systolic pulmonary artery (PA) pressure decreased from 47.0 ± 16.7 mmHg before occlusion to 29.0 ± 7.4 mmHg after occlusion (P ≤ 0.001)., mean diastolic PA pressure from 25.0 ± 10.9 mmHg to 14.8 ± 6.0 mmHg and the average mean PA pressure decreased from 35.9 ± 13.5 mmHg to 21.1 ± 6.5 mmHg. Complications (4.8%) included device and coil embolization, bleeding, and pulse loss. On follow-up (mean duration of 36.1 ± 12.1 months, range 12-62 months), 137 patients were in functional class 1, 3 had residual shunt, 2 had device migration and one patient had persisting pulse loss. Successful duct closure was achieved in the vast majority of patients, even though the ducts were larger and significant number of them had pulmonary hypertension in this high altitude group. There was a relatively higher incidence of residual shunts and device migration in this series, generally due to the nonavailability of optimal device and surgical support. Long-term follow-up is required before we can draw conclusions with regard to the sustainability of drop in PA pressures. Septal Occluder devices may be a possible alternative for large tubular or window-type ducts with severe pulmonary hypertension, where there may be concerns about the size and stability of duct occluder devices.

An Audit to Evaluate the Safety and Efficacy of Percutaneous Endoscopic Gastrostomy Placement in Patients with Learning Disabilities

ERIC Educational Resources Information Center

Ayres, Lachlan; Black, Chris; Scheepers, Mark; Shaw, Ian

2015-01-01

Percutaneous endoscopic gastrostomy insertion is an effective method of providing enteral nutrition to patients with neurologically unsafe swallowing or failure of feeding. Patients with severe learning disabilities may develop unsafe swallowing and benefit from percutaneous endoscopic gastrostomy placement. It is unclear whether this intervention…

Percutaneous Trigger Finger Release: A Cost-effectiveness Analysis.

PubMed

Gancarczyk, Stephanie M; Jang, Eugene S; Swart, Eric P; Makhni, Eric C; Kadiyala, Rajendra Kumar

2016-07-01

Percutaneous trigger finger releases (TFRs) performed in the office setting are becoming more prevalent. This study compares the costs of in-hospital open TFRs, open TFRs performed in ambulatory surgical centers (ASCs), and in-office percutaneous releases. An expected-value decision-analysis model was constructed from the payer perspective to estimate total costs of the three competing treatment strategies for TFR. Model parameters were estimated based on the best available literature and were tested using multiway sensitivity analysis. Percutaneous TFR performed in the office and then, if needed, revised open TFR performed in the ASC, was the most cost-effective strategy, with an attributed cost of $603. The cost associated with an initial open TFR performed in the ASC was approximately 7% higher. Initial open TFR performed in the hospital was the least cost-effective, with an attributed cost nearly twice that of primary percutaneous TFR. An initial attempt at percutaneous TFR is more cost-effective than an open TFR. Currently, only about 5% of TFRs are performed in the office; therefore, a substantial opportunity exists for cost savings in the future. Decision model level II.

Quality of canine spermatozoa retrieved by percutaneous epididymal sperm aspiration.

PubMed

Varesi, S; Vernocchi, V; Faustini, M; Luvoni, G C

2013-02-01

To investigate the feasibility of percutaneous epididymal sperm aspiration in dogs and whether it might provide a population of epididymal spermatozoa similar to the population that can be obtained by processing isolated epididymis caudae. Concentration and total sperm number, motility, morphology and acrosomal integrity of spermatozoa retrieved by percutaneous epididymal sperm aspiration, in vitro aspiration and mincing of the cauda of the epididymis were compared. Percutaneous epididymal sperm aspiration is a feasible procedure to retrieve a population of spermatozoa in dogs. Quality is similar to that of spermatozoa collected in vitro, although a wide variation amongst animals was observed. In case of ejaculation failure due to pathological conditions in dogs, the collection of spermatozoa from the cauda of the epididymis could be an option for providing gametes for assisted reproductive technologies. Percutaneous epididymal sperm aspiration can be used in dogs with compromised reproductive performance, in which orchiectomy cannot be performed for medical or owner reasons. Further studies aimed to investigate whether the percutaneous epididymal sperm aspiration technique might be feasible for repeated semen collection and to accurately evaluate side effects are required. © 2013 British Small Animal Veterinary Association.

Percutaneous endoscopic gastrostomy versus nasogastric tube feeding for patients with head and neck cancer: a systematic review

PubMed Central

Wang, Jinfeng; Liu, Minjie; Liu, Chao; Ye, Yun; Huang, Guanhong

2014-01-01

There are two main enteral feeding strategies—namely nasogastric (NG) tube feeding and percutaneous gastrostomy—used to improve the nutritional status of patients with head and neck cancer (HNC). But up till now there has been no consistent evidence about which method of enteral feeding is the optimal method for this patient group. To compare the effectiveness of percutaneous gastrostomy and NGT feeding in patients with HNC, relevant literature was identified through Medline, Embase, Pubmed, Cochrane, Wiley and manual searches. We included randomized controlled trials (RCTs) and non-experimental studies comparing percutaneous gastrostomy—including percutaneous endoscopic gastrostomy (PEG) and percutaneous fluoroscopic gastrostomy (PFG) —with NG for HNC patients. Data extraction recorded characteristics of intervention, type of study and factors that contributed to the methodological quality of the individual studies. Data were then compared with respect to nutritional status, duration of feeding, complications, radiotherapy delays, disease-free survival and overall survival. Methodological quality of RCTs and non-experimental studies were assessed with separate standard grading scales. It became apparent from our studies that both feeding strategies have advantages and disadvantages. PMID:24453356

Percutaneous endoscopic gastrostomy versus nasogastric tube feeding for patients with head and neck cancer: a systematic review.

PubMed

Wang, Jinfeng; Liu, Minjie; Liu, Chao; Ye, Yun; Huang, Guanhong

2014-05-01

There are two main enteral feeding strategies-namely nasogastric (NG) tube feeding and percutaneous gastrostomy-used to improve the nutritional status of patients with head and neck cancer (HNC). But up till now there has been no consistent evidence about which method of enteral feeding is the optimal method for this patient group. To compare the effectiveness of percutaneous gastrostomy and NGT feeding in patients with HNC, relevant literature was identified through Medline, Embase, Pubmed, Cochrane, Wiley and manual searches. We included randomized controlled trials (RCTs) and non-experimental studies comparing percutaneous gastrostomy-including percutaneous endoscopic gastrostomy (PEG) and percutaneous fluoroscopic gastrostomy (PFG) -with NG for HNC patients. Data extraction recorded characteristics of intervention, type of study and factors that contributed to the methodological quality of the individual studies. Data were then compared with respect to nutritional status, duration of feeding, complications, radiotherapy delays, disease-free survival and overall survival. Methodological quality of RCTs and non-experimental studies were assessed with separate standard grading scales. It became apparent from our studies that both feeding strategies have advantages and disadvantages.

Interval stability for complex systems

NASA Astrophysics Data System (ADS)

Klinshov, Vladimir V.; Kirillov, Sergey; Kurths, Jürgen; Nekorkin, Vladimir I.

2018-04-01

Stability of dynamical systems against strong perturbations is an important problem of nonlinear dynamics relevant to many applications in various areas. Here, we develop a novel concept of interval stability, referring to the behavior of the perturbed system during a finite time interval. Based on this concept, we suggest new measures of stability, namely interval basin stability (IBS) and interval stability threshold (IST). IBS characterizes the likelihood that the perturbed system returns to the stable regime (attractor) in a given time. IST provides the minimal magnitude of the perturbation capable to disrupt the stable regime for a given interval of time. The suggested measures provide important information about the system susceptibility to external perturbations which may be useful for practical applications. Moreover, from a theoretical viewpoint the interval stability measures are shown to bridge the gap between linear and asymptotic stability. We also suggest numerical algorithms for quantification of the interval stability characteristics and demonstrate their potential for several dynamical systems of various nature, such as power grids and neural networks.

Niosomes encapsulating Ibuprofen-cyclodextrin complexes: preparation and characterization.

PubMed

Marianecci, Carlotta; Rinaldi, Federica; Esposito, Sara; Di Marzio, Luisa; Carafa, Maria

2013-08-01

A new delivery system based on ibuprofen-β-cyclodextrin (βCd) complexation and its loading into non-ionic surfactant vesicles (NSVs) was developed to improve ibuprofen therapeutic efficacy in topical formulations. The proposed strategy exploits the well known solubilizing and stabilizing properties of cyclodextrins together with the high tolerability and percutaneous absorption enhancing properties of NSVs. The complexing capacity of Cds in the presence of Ibuprofen in aqueous solution was evaluated by means of phase solubility studies. The technique used to obtain solid ibuprofen-βCd complexes was the co-lyophilization method. The influence of the preparation method on the physicochemical properties of the final product was evaluated by means of Fourier Transform Infrared Spectroscopy and Differential scanning calorimetry studies. Ibuprofen-βCd complexes were included in Tween 20/Cholesterol vesicles and characterized in terms of size, zeta (ζ)-potential, stability, drug entrapment efficiency and drug release. The best ibuprofen-βCd-NSV system exhibited in vitro drug permeation properties significantly improved with respect to those of the plain drug suspension.

Management of recent unstable fractures of the pelvic ring. An update conference supported by the Club Bassin Cotyle. (Pelvis-Acetabulum Club).

PubMed

Tonetti, J

2013-02-01

Traumatic injury to the pelvic ring is a result of high energy trauma in young patients. These osteo-ligamentous injuries are associated with numerous lesions including retroperitoneal hematoma, urogenital, cutaneous and neurological (lumbosacral plexus). The goal of initial management is to restore vital indicators, urinary excretion function and protect the patient from infectious complications. An emergency decisional algorithm helps manage haemodynamic instability. Initial bone and ligament procedures should reduce displacement and make it possible for the patient the wait until his condition is stable enough for definitive surgical fixation. The goal of surgical treatment is to avoid nonunion and malunion. Stable fixation of the posterior arch after reduction favors union. Different techniques can be used by the posterior, anterior ilio-inguinal or lateral percutaneous approaches. Anterior fixation is discussed to improve reduction and increase the stability obtained with a posterior procedure. Anterior external fixation is useful to temporarily reinforce posterior stabilization. Copyright © 2013. Published by Elsevier Masson SAS.

Dynamic water patterns change the stability of the collapsed filter conformation of the KcsA K+ channel

PubMed Central

2017-01-01

The selectivity filter of the KcsA K+ channel has two typical conformations—the conductive and the collapsed conformations, respectively. The transition from the conductive to the collapsed filter conformation can represent the process of inactivation that depends on many environmental factors. Water molecules permeating behind the filter can influence the collapsed filter stability. Here we perform the molecular dynamics simulations to study the stability of the collapsed filter of the KcsA K+ channel under the different water patterns. We find that the water patterns are dynamic behind the collapsed filter and the filter stability increases with the increasing number of water molecules. In addition, the stability increases significantly when water molecules distribute uniformly behind the four monomeric filter chains, and the stability is compromised if water molecules only cluster behind one or two adjacent filter chains. The altered filter stabilities thus suggest that the collapsed filter can inactivate gradually under the dynamic water patterns. We also demonstrate how the different water patterns affect the filter recovery from the collapsed conformation. PMID:29049423

Dynamic water patterns change the stability of the collapsed filter conformation of the KcsA K+ channel.

PubMed

Wu, Di

2017-01-01

The selectivity filter of the KcsA K+ channel has two typical conformations-the conductive and the collapsed conformations, respectively. The transition from the conductive to the collapsed filter conformation can represent the process of inactivation that depends on many environmental factors. Water molecules permeating behind the filter can influence the collapsed filter stability. Here we perform the molecular dynamics simulations to study the stability of the collapsed filter of the KcsA K+ channel under the different water patterns. We find that the water patterns are dynamic behind the collapsed filter and the filter stability increases with the increasing number of water molecules. In addition, the stability increases significantly when water molecules distribute uniformly behind the four monomeric filter chains, and the stability is compromised if water molecules only cluster behind one or two adjacent filter chains. The altered filter stabilities thus suggest that the collapsed filter can inactivate gradually under the dynamic water patterns. We also demonstrate how the different water patterns affect the filter recovery from the collapsed conformation.

Percutaneous Portal Vein Access and Transhepatic Tract Hemostasis

PubMed Central

Saad, Wael E. A.; Madoff, David C.

2012-01-01

Percutaneous portal vein interventions require minimally invasive access to the portal venous system. Common approaches to the portal vein include transjugular hepatic vein to portal vein access and direct transhepatic portal vein access. A major concern of the transhepatic route is the risk of postprocedural bleeding, which is increased when patients are anticoagulated or receiving pharmaceutical thrombolytic therapy. Thus percutaneous portal vein access and subsequent closure are important technical parts of percutaneous portal vein procedures. At present, various techniques have been used for either portal access or subsequent transhepatic tract closure and hemostasis. Regardless of the method used, meticulous technique is required to achieve the overall safety and effectiveness of portal venous procedures. This article reviews the various techniques of percutaneous transhepatic portal vein access and the various closure and hemostatic methods used to reduce the risk of postprocedural bleeding. PMID:23729976

Imaging for percutaneous renal access and management of renal calculi.

PubMed

Park, Sangtae; Pearle, Margaret S

2006-08-01

Percutaneous renal stone surgery requires detailed imaging to define stone burden and delineate the anatomy of the kidney and nearby organs. It is also essential to carry out safe percutaneous access and to assess postoperative outcomes. The emergence of CT as the imaging modality of choice for detecting renal calculi and the ability of CT urography with or without three-dimensional reconstruction to delineate the collecting system makes this the most versatile and sensitive imaging modality for pre- and postoperative evaluation. At present, intravenous urogram continues to play an important role in the evaluation of patients considered for percutaneous nephrostolithotomy. Fluoroscopy re-mains the mainstay of intraoperative imaging, although ultrasound is a useful alternative. Selection and application of appropriate imaging modalities for patients undergoing per-cutaneous nephrostolithotomy enhances the safety and success of the procedure.

The Incidence of Adjacent Segment Degeneration after the Use of a Versatile Dynamic Hybrid Stabilization Device in Lumbar Stenosis: Results of a 5–8-Year Follow-up

PubMed Central

Dobran, Mauro; Esposito, Domenico Paolo; Gladi, Maurizio; Scerrati, Massimo; Iacoangeli, Maurizio

2018-01-01

Study Design Retrospective study with long-term follow-up. Purpose To evaluate the long-term incidence of adjacent segment degeneration (ASD) and clinical outcomes in a consecutive series of patients who underwent spinal decompression associated with dynamic or hybrid stabilization with a Flex+TM stabilization system (SpineVision, Antony, France) for lumbar spinal stenosis. Overview of Literature The incidence of ASD and clinical outcomes following dynamic or hybrid stabilization with the Flex+TM system used for lumbar spinal stenosis have not been well investigated. Methods Twenty-one patients with lumbar stenosis and probable post-decompressive spinal instability underwent decompressive laminectomy followed by spinal stabilization using the Flex+TM stabilization system. The indication for a mono-level dynamic stabilization was a preoperative magnetic resonance imaging (MRI) demonstrating evidence of severe disc disease associated with severe spinal stenosis. The hybrid stabilization (rigid-dynamic) system was used for multilevel laminectomies with associated initial degenerative scoliosis, first-grade spondylolisthesis, or rostral pathology. Results The improvement in Visual Analog Scale and Oswestry Disability Index scores at follow-up were statistically significant (p<0.0001 and p<0.0001, respectively). At the 5–8-year follow-up, clinical examination, MRI, and X-ray findings showed an ASD complication with pain and disability in one of 21 patients. The clinical outcomes were similar in patients treated with dynamic or hybrid fixation. Conclusions Patients treated with laminectomy and Flex+TM stabilization presented a satisfactory clinical outcome after 5–8 years of follow-up, and ASD incidence in our series was 4.76% (one patient out of 21). We are aware that this is a small series, but our long-term follow-up may be sufficient to contribute to the expanding body of literature on the development of symptomatic ASD associated with dynamic or hybrid fixation. PMID:29713407

Signal Processing Methods for Liquid Rocket Engine Combustion Stability Assessments

NASA Technical Reports Server (NTRS)

Kenny, R. Jeremy; Lee, Erik; Hulka, James R.; Casiano, Matthew

2011-01-01

The J2X Gas Generator engine design specifications include dynamic, spontaneous, and broadband combustion stability requirements. These requirements are verified empirically based high frequency chamber pressure measurements and analyses. Dynamic stability is determined with the dynamic pressure response due to an artificial perturbation of the combustion chamber pressure (bomb testing), and spontaneous and broadband stability are determined from the dynamic pressure responses during steady operation starting at specified power levels. J2X Workhorse Gas Generator testing included bomb tests with multiple hardware configurations and operating conditions, including a configuration used explicitly for engine verification test series. This work covers signal processing techniques developed at Marshall Space Flight Center (MSFC) to help assess engine design stability requirements. Dynamic stability assessments were performed following both the CPIA 655 guidelines and a MSFC in-house developed statistical-based approach. The statistical approach was developed to better verify when the dynamic pressure amplitudes corresponding to a particular frequency returned back to pre-bomb characteristics. This was accomplished by first determining the statistical characteristics of the pre-bomb dynamic levels. The pre-bomb statistical characterization provided 95% coverage bounds; these bounds were used as a quantitative measure to determine when the post-bomb signal returned to pre-bomb conditions. The time for post-bomb levels to acceptably return to pre-bomb levels was compared to the dominant frequency-dependent time recommended by CPIA 655. Results for multiple test configurations, including stable and unstable configurations, were reviewed. Spontaneous stability was assessed using two processes: 1) characterization of the ratio of the peak response amplitudes to the excited chamber acoustic mode amplitudes and 2) characterization of the variability of the peak response's frequency over the test duration. This characterization process assists in evaluating the discreteness of a signal as well as the stability of the chamber response. Broadband stability was assessed using a running root-mean-square evaluation. These techniques were also employed, in a comparative analysis, on available Fastrac data, and these results are presented here.

Five-year evolution of reperfusion strategies and early mortality in patients with ST-segment elevation myocardial infarction in France.

PubMed

El Khoury, Carlos; Bochaton, Thomas; Flocard, Elodie; Serre, Patrice; Tomasevic, Danka; Mewton, Nathan; Bonnefoy-Cudraz, Eric

2017-10-01

To assess 5-year evolutions in reperfusion strategies and early mortality in patients with ST-segment elevation myocardial infarction. Using data from the French RESCUe network, we studied patients with ST-segment elevation myocardial infarction treated in mobile intensive care units between 2009 and 2013. Among 2418 patients (median age 62 years; 78.5% male), 2119 (87.6%) underwent primary percutaneous coronary intervention and 299 (12.4%) pre-hospital thrombolysis (94.0% of whom went on to undergo percutaneous coronary intervention). Use of primary percutaneous coronary intervention increased from 78.4% in 2009 to 95.9% in 2013 ( P trend <0.001). Median delays included: first medical contact to percutaneous coronary intervention centre 48 minutes; first medical contact to balloon inflation 94 minutes; and percutaneous coronary intervention centre to balloon inflation 43 minutes. Times from symptom onset to first medical contact and first medical contact to thrombolysis remained stable during 2009-2013, but times from symptom onset to first balloon inflation, and first medical contact to percutaneous coronary intervention centre to first balloon inflation decreased ( P<0.001). Among patients with known timings, 2146 (89.2%) had a first medical contact to percutaneous coronary intervention centre delay ⩽90 minutes, while 260 (10.8%) had a longer delay, with no significant variation over time. Primary percutaneous coronary intervention use increased over time in both delay groups, but was consistently higher in the ⩽90 versus >90 minutes delay group (83.0% in 2009 to 97.7% in 2013; P trend <0.001 versus 34.1% in 2009 to 79.2% in 2013; P trend <0.001). In-hospital (4-6%) and 30-day (6-8%) mortalities remained stable from 2009 to 2013. In the RESCUe network, the use of primary percutaneous coronary intervention increased from 2009 to 2013, in line with guidelines, but there was no evolution in early mortality.

Robust controller designs for second-order dynamic system: A virtual passive approach

NASA Technical Reports Server (NTRS)

Juang, Jer-Nan; Phan, Minh

1990-01-01

A robust controller design is presented for second-order dynamic systems. The controller is model-independent and itself is a virtual second-order dynamic system. Conditions on actuator and sensor placements are identified for controller designs that guarantee overall closed-loop stability. The dynamic controller can be viewed as a virtual passive damping system that serves to stabilize the actual dynamic system. The control gains are interpreted as virtual mass, spring, and dashpot elements that play the same roles as actual physical elements in stability analysis. Position, velocity, and acceleration feedback are considered. Simple examples are provided to illustrate the physical meaning of this controller design.

Updates on Percutaneous Radiologic Gastrostomy/Gastrojejunostomy and Jejunostomy

PubMed Central

Park, Auh-Whan

2010-01-01

Gastrostomy placement for nutritional support for patients with inadequate oral intake has been attempted using surgical, endoscopic, and, more recently, percutaneous radiologically guided methods. Surgical gastrostomy has been superseded by both endoscopic and radiologic gastrostomy. We describe herein the indications, contraindications, patient preparations, techniques, complications, and aftercare with regard to radiologic gastrostomy. In addition, we discuss the available tube types and their perceived advantages. There remain some controversies regarding gastropexy performance and primary percutaneous gastrojejunostomy. Percutaneous jejunostomy is indicated for patients whose stomach is inaccessible for gastrostomy placement or for those who have had a previous gastrectomy. PMID:21103291

Percutaneous Relief of Tension Pneumomediastinum in a Child

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

Chau, Helen Hoi-lun; Kwok, Philip Chong-hei; Lai, Albert Kwok-hung

2003-11-15

The purpose of this article was to describe the experience of relieving tension pneumomediastinum by a fluoroscopic-guided percutaneous method. We inserted a percutaneous drainage catheter with a Heimlich valve under fluoroscopic guidance to relieve the tension pneumomediastinum in a 2-year-old girl who suffered from dermatomyositis with lung involvement. This allowed immediate relief without the need for surgery. The procedure was repeated for relapsed tension pneumomediastinum. Good immediate results were achieved in each attempt. We conclude that percutaneous relief of pneumomediastinum under fluoroscopic guidance can be performed safely and rapidly in patients not fit for surgery.

Occlusion of an Intraosseous Arteriovenous Malformation With Percutaneous Injection of Polymethylmethacrylate

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

Ierardi, Anna Maria, E-mail: amierardi@yahoo.it; Mangini, Monica, E-mail: monica.mangini@tin.it; Vaghi, Massimo, E-mail: vaghim@yahoo.it

Primary intraosseous arteriovenous malformations are rare. Many minimally invasive procedures can be considered preoperative steps and/or definitive treatment. The case reported regards a young woman with a voluminous arteriovenous extratroncular infiltrating malformation of the humerus. She underwent several treatments, but none of them was completely occlusive. The last treatment consisted of direct percutaneous puncture of the intraosseous alteration and injection of polymethylmethacrylate (PMMA), which is normally used in percutaneous vertebroplasty. We obtained complete occlusion of the humerus lytic lesion. To the best of our knowledge, this represents the first case of intraosseous AVM treated by percutaneous injection of PMMA.

Percutaneous Direct Puncture Embolization with N-butyl-cyanoacrylate for High-flow Priapism

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

Tokue, Hiroyuki, E-mail: tokue@s2.dion.ne.jp; Shibuya, Kei; Ueno, Hiroyuki

There are many treatment options in high-flow priapism. Those mentioned most often are watchful waiting, Doppler-guided compression, endovascular highly selective embolization, and surgery. We present a case of high-flow priapism in a 57-year-old man treated by percutaneous direct puncture embolization of a post-traumatic left cavernosal arteriovenous fistula using N-butyl-cyanoacrylate. Erectile function was preserved during a 12-month follow-up. No patients with percutaneous direct puncture embolization for high-flow priapism have been reported previously. Percutaneous direct puncture embolization is a potentially useful and safe method for management of high-flow priapism.

Intrarater test-retest reliability of static and dynamic stability indexes measurement using the Biodex Stability System during unilateral stance.

PubMed

Arifin, Nooranida; Abu Osman, Noor Azuan; Wan Abas, Wan Abu Bakar

2014-04-01

The measurements of postural balance often involve measurement error, which affects the analysis and interpretation of the outcomes. In most of the existing clinical rehabilitation research, the ability to produce reliable measures is a prerequisite for an accurate assessment of an intervention after a period of time. Although clinical balance assessment has been performed in previous study, none has determined the intrarater test-retest reliability of static and dynamic stability indexes during dominant single stance. In this study, one rater examined 20 healthy university students (female=12, male=8) in two sessions separated by 7 day intervals. Three stability indexes--the overall stability index (OSI), anterior/posterior stability index (APSI), and medial/ lateral stability index (MLSI) in static and dynamic conditions--were measured during single dominant stance. Intraclass correlation coefficient (ICC), standard error measurement (SEM) and 95% confidence interval (95% CI) were calculated. Test-retest ICCs for OSI, APSI, and MLSI were 0.85, 0.78, and 0.84 during static condition and were 0.77, 0.77, and 0.65 during dynamic condition, respectively. We concluded that the postural stability assessment using Biodex stability system demonstrates good-to-excellent test-retest reliability over a 1 week time interval.

Open versus percutaneous instrumentation in thoracolumbar fractures: magnetic resonance imaging comparison of paravertebral muscles after implant removal.

PubMed

Ntilikina, Yves; Bahlau, David; Garnon, Julien; Schuller, Sébastien; Walter, Axel; Schaeffer, Mickaël; Steib, Jean-Paul; Charles, Yann Philippe

2017-08-01

OBJECTIVE Percutaneous instrumentation in thoracolumbar fractures is intended to decrease paravertebral muscle damage by avoiding dissection. The aim of this study was to compare muscles at instrumented levels in patients who were treated by open or percutaneous surgery. METHODS Twenty-seven patients underwent open instrumentation, and 65 were treated percutaneously. A standardized MRI protocol using axial T1-weighted sequences was performed at a minimum 1-year follow-up after implant removal. Two independent observers measured cross-sectional areas (CSAs, in cm 2 ) and region of interest (ROI) signal intensity (in pixels) of paravertebral muscles by using OsiriX at the fracture level, and at cranial and caudal instrumented pedicle levels. An interobserver comparison was made using the Bland-Altman method. Reference ROI muscle was assessed in the psoas and ROI fat subcutaneously. The ratio ROI-CSA/ROI-fat was compared for patients treated with open versus percutaneous procedures by using a linear mixed model. A linear regression analyzed additional factors: age, sex, body mass index (BMI), Pfirrmann grade of adjacent discs, and duration of instrumentation in situ. RESULTS The interobserver agreement was good for all CSAs. The average CSA for the entire spine was 15.7 cm 2 in the open surgery group and 18.5 cm 2 in the percutaneous group (p = 0.0234). The average ROI-fat and ROI-muscle signal intensities were comparable: 497.1 versus 483.9 pixels for ROI-fat and 120.4 versus 111.7 pixels for ROI-muscle in open versus percutaneous groups. The ROI-CSA varied between 154 and 226 for open, and between 154 and 195 for percutaneous procedures, depending on instrumented levels. A significant difference of the ROI-CSA/ROI-fat ratio (0.4 vs 0.3) was present at fracture levels T12-L1 (p = 0.0329) and at adjacent cranial (p = 0.0139) and caudal (p = 0.0100) instrumented levels. Differences were not significant at thoracic levels. When adjusting based on age, BMI, and Pfirrmann grade, a significant difference between open and percutaneous procedures regarding the ROI-CSA/ROI-fat ratio was present in the lumbar spine (p < 0.01). Sex and duration of instrumentation had no significant influence. CONCLUSIONS Percutaneous instrumentation decreased muscle atrophy compared with open surgery. The MRI signal differences for T-12 and L-1 fractures indicated less fat infiltration within CSAs in patients who received percutaneous treatment. Differences were not evidenced at thoracic levels, where CSAs were smaller. Fat infiltration was not significantly different at lumbar levels with either procedure in elderly patients with associated discopathy and higher BMI. In younger patients, there was less fat infiltration of lumbar paravertebral muscles with percutaneous procedures.

Dynamic stability requirements during gait and standing exergames on the wii fit® system in the elderly

PubMed Central

2012-01-01

Background In rehabilitation, training intensity is usually adapted to optimize the trained system to attain better performance (overload principle). However, in balance rehabilitation, the level of intensity required during training exercises to optimize improvement in balance has rarely been studied, probably due to the difficulty in quantifying the stability level during these exercises. The goal of the present study was to test whether the stabilizing/destabilizing forces model could be used to analyze how stability is challenged during several exergames, that are more and more used in balance rehabilitation, and a dynamic functional task, such as gait. Methods Seven healthy older adults were evaluated with three-dimensional motion analysis during gait at natural and fast speed, and during three balance exergames (50/50 Challenge, Ski Slalom and Soccer). Mean and extreme values for stabilizing force, destabilizing force and the ratio of the two forces (stability index) were computed from kinematic and kinetic data to determine the mean and least level of dynamic, postural and overall balance stability, respectively. Results Mean postural stability was lower (lower mean destabilizing force) during the 50/50 Challenge game than during all the other tasks, but peak postural instability moments were less challenging during this game than during any of the other tasks, as shown by the minimum destabilizing force values. Dynamic stability was progressively more challenged (higher mean and maximum stabilizing force) from the 50/50 Challenge to the Soccer and Slalom games, to the natural gait speed task and to the fast gait speed task, increasing the overall stability difficulty (mean and minimum stability index) in the same manner. Conclusions The stabilizing/destabilizing forces model can be used to rate the level of balance requirements during different tasks such as gait or exergames. The results of our study showed that postural stability did not differ much between the evaluated tasks (except for the 50/50 Challenge), compared to dynamic stability, which was significantly less challenged during the games than during the functional tasks. Games with greater centre of mass displacements and changes in the base of support are likely to stimulate balance control enough to see improvements in balance during dynamic functional tasks, and could be tested in pathological populations with the approach used here. PMID:22607025

Control of nonlinear systems with applications to constrained robots and spacecraft attitude stabilization

NASA Technical Reports Server (NTRS)

Krishnan, Hariharan

1993-01-01

This thesis is organized in two parts. In Part 1, control systems described by a class of nonlinear differential and algebraic equations are introduced. A procedure for local stabilization based on a local state realization is developed. An alternative approach to local stabilization is developed based on a classical linearization of the nonlinear differential-algebraic equations. A theoretical framework is established for solving a tracking problem associated with the differential-algebraic system. First, a simple procedure is developed for the design of a feedback control law which ensures, at least locally, that the tracking error in the closed loop system lies within any given bound if the reference inputs are sufficiently slowly varying. Next, by imposing additional assumptions, a procedure is developed for the design of a feedback control law which ensures that the tracking error in the closed loop system approaches zero exponentially for reference inputs which are not necessarily slowly varying. The control design methodologies are used for simultaneous force and position control in constrained robot systems. The differential-algebraic equations are shown to characterize the slow dynamics of a certain nonlinear control system in nonstandard singularly perturbed form. In Part 2, the attitude stabilization (reorientation) of a rigid spacecraft using only two control torques is considered. First, the case of momentum wheel actuators is considered. The complete spacecraft dynamics are not controllable. However, the spacecraft dynamics are small time locally controllable in a reduced sense. The reduced spacecraft dynamics cannot be asymptotically stabilized using continuous feedback, but a discontinuous feedback control strategy is constructed. Next, the case of gas jet actuators is considered. If the uncontrolled principal axis is not an axis of symmetry, the complete spacecraft dynamics are small time locally controllable. However, the spacecraft attitude cannot be asymptotically stabilized using continuous feedback, but a discontinuous stabilizing feedback control strategy is constructed. If the uncontrolled principal axis is an axis of symmetry, the complete spacecraft dynamics cannot be stabilized. However, the spacecraft dynamics are small time locally controllable in a reduced sense. The reduced spacecraft dynamics cannot be asymptotically stabilized using continuous feedback, but again a discontinuous feedback control strategy is constructed.

Does dynamic stability govern propulsive force generation in human walking?

PubMed Central

Browne, Michael G.

2017-01-01

Before succumbing to slower speeds, older adults may walk with a diminished push-off to prioritize stability over mobility. However, direct evidence for trade-offs between push-off intensity and balance control in human walking, independent of changes in speed, has remained elusive. As a critical first step, we conducted two experiments to investigate: (i) the independent effects of walking speed and propulsive force (FP) generation on dynamic stability in young adults, and (ii) the extent to which young adults prioritize dynamic stability in selecting their preferred combination of walking speed and FP generation. Subjects walked on a force-measuring treadmill across a range of speeds as well as at constant speeds while modulating their FP according to a visual biofeedback paradigm based on real-time force measurements. In contrast to improvements when walking slower, walking with a diminished push-off worsened dynamic stability by up to 32%. Rather, we find that young adults adopt an FP at their preferred walking speed that maximizes dynamic stability. One implication of these findings is that the onset of a diminished push-off in old age may independently contribute to poorer balance control and precipitate slower walking speeds. PMID:29291129

Does dynamic stability govern propulsive force generation in human walking?

PubMed

Browne, Michael G; Franz, Jason R

2017-11-01

Before succumbing to slower speeds, older adults may walk with a diminished push-off to prioritize stability over mobility. However, direct evidence for trade-offs between push-off intensity and balance control in human walking, independent of changes in speed, has remained elusive. As a critical first step, we conducted two experiments to investigate: (i) the independent effects of walking speed and propulsive force ( F P ) generation on dynamic stability in young adults, and (ii) the extent to which young adults prioritize dynamic stability in selecting their preferred combination of walking speed and F P generation. Subjects walked on a force-measuring treadmill across a range of speeds as well as at constant speeds while modulating their F P according to a visual biofeedback paradigm based on real-time force measurements. In contrast to improvements when walking slower, walking with a diminished push-off worsened dynamic stability by up to 32%. Rather, we find that young adults adopt an F P at their preferred walking speed that maximizes dynamic stability. One implication of these findings is that the onset of a diminished push-off in old age may independently contribute to poorer balance control and precipitate slower walking speeds.

Percutaneous Sclerotherapy With OK-432 of a Cervicomediastinal Lymphangioma.

PubMed

Golinelli, Gloria; Toso, Andrea; Borello, Giovanni; Aluffi, Paolo; Pia, Francesco

2015-11-01

The present study reports a case of percutaneous sclerotherapy of a giant cystic cervicomediastinal lymphangioma using OK-432. To the best of our knowledge, percutaneous sclerotherapy of a mediastinal lymphangioma using OK 432 has not previously been reported in the English literature. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Walking in simulated Martian gravity: influence of the portable life support system's design on dynamic stability.

PubMed

Scott-Pandorf, Melissa M; O'Connor, Daniel P; Layne, Charles S; Josić, Kresimir; Kurz, Max J

2009-09-01

With human exploration of the moon and Mars on the horizon, research considerations for space suit redesign have surfaced. The portable life support system (PLSS) used in conjunction with the space suit during the Apollo missions may have influenced the dynamic balance of the gait pattern. This investigation explored potential issues with the PLSS design that may arise during the Mars exploration. A better understanding of how the location of the PLSS load influences the dynamic stability of the gait pattern may provide insight, such that space missions may have more productive missions with a smaller risk of injury and damaging equipment while falling. We explored the influence the PLSS load position had on the dynamic stability of the walking pattern. While walking, participants wore a device built to simulate possible PLSS load configurations. Floquet and Lyapunov analysis techniques were used to quantify the dynamic stability of the gait pattern. The dynamic stability of the gait pattern was influenced by the position of load. PLSS loads that are placed high and forward on the torso resulted in less dynamically stable walking patterns than loads placed evenly and low on the torso. Furthermore, the kinematic results demonstrated that all joints of the lower extremity may be important for adjusting to different load placements and maintaining dynamic stability. Space scientists and engineers may want to consider PLSS designs that distribute loads evenly and low, and space suit designs that will not limit the sagittal plane range of motion at the lower extremity joints.

Kinematic variability, fractal dynamics and local dynamic stability of treadmill walking

PubMed Central

2011-01-01

Background Motorized treadmills are widely used in research or in clinical therapy. Small kinematics, kinetics and energetics changes induced by Treadmill Walking (TW) as compared to Overground Walking (OW) have been reported in literature. The purpose of the present study was to characterize the differences between OW and TW in terms of stride-to-stride variability. Classical (Standard Deviation, SD) and non-linear (fractal dynamics, local dynamic stability) methods were used. In addition, the correlations between the different variability indexes were analyzed. Methods Twenty healthy subjects performed 10 min TW and OW in a random sequence. A triaxial accelerometer recorded trunk accelerations. Kinematic variability was computed as the average SD (MeanSD) of acceleration patterns among standardized strides. Fractal dynamics (scaling exponent α) was assessed by Detrended Fluctuation Analysis (DFA) of stride intervals. Short-term and long-term dynamic stability were estimated by computing the maximal Lyapunov exponents of acceleration signals. Results TW did not modify kinematic gait variability as compared to OW (multivariate T2, p = 0.87). Conversely, TW significantly modified fractal dynamics (t-test, p = 0.01), and both short and long term local dynamic stability (T2 p = 0.0002). No relationship was observed between variability indexes with the exception of significant negative correlation between MeanSD and dynamic stability in TW (3 × 6 canonical correlation, r = 0.94). Conclusions Treadmill induced a less correlated pattern in the stride intervals and increased gait stability, but did not modify kinematic variability in healthy subjects. This could be due to changes in perceptual information induced by treadmill walking that would affect locomotor control of the gait and hence specifically alter non-linear dependencies among consecutive strides. Consequently, the type of walking (i.e. treadmill or overground) is important to consider in each protocol design. PMID:21345241

Interpretation of dynamic tensile behavior by austenite stability in ferrite-austenite duplex lightweight steels.

PubMed

Park, Jaeyeong; Jo, Min Cheol; Jeong, Hyeok Jae; Sohn, Seok Su; Kwak, Jai-Hyun; Kim, Hyoung Seop; Lee, Sunghak

2017-11-16

Phenomena occurring in duplex lightweight steels under dynamic loading are hardly investigated, although its understanding is essentially needed in applications of automotive steels. In this study, quasi-static and dynamic tensile properties of duplex lightweight steels were investigated by focusing on how TRIP and TWIP mechanisms were varied under the quasi-static and dynamic loading conditions. As the annealing temperature increased, the grain size and volume fraction of austenite increased, thereby gradually decreasing austenite stability. The strain-hardening rate curves displayed a multiple-stage strain-hardening behavior, which was closely related with deformation mechanisms. Under the dynamic loading, the temperature rise due to adiabatic heating raised the austenite stability, which resulted in the reduction in the TRIP amount. Though the 950 °C-annealed specimen having the lowest austenite stability showed the very low ductility and strength under the quasi-static loading, it exhibited the tensile elongation up to 54% as well as high strain-hardening rate and tensile strength (1038 MPa) due to appropriate austenite stability under dynamic loading. Since dynamic properties of the present duplex lightweight steels show the excellent strength-ductility combination as well as continuously high strain hardening, they can be sufficiently applied to automotive steel sheets demanded for stronger vehicle bodies and safety enhancement.

Is percutaneous repair better than open repair in acute Achilles tendon rupture?

PubMed

Henríquez, Hugo; Muñoz, Roberto; Carcuro, Giovanni; Bastías, Christian

2012-04-01

Open repair of Achilles tendon rupture has been associated with higher levels of wound complications than those associated with percutaneous repair. However, some studies suggest there are higher rerupture rates and sural nerve injuries with percutaneous repair. We compared the two types of repairs in terms of (1) function (muscle strength, ankle ROM, calf and ankle perimeter, single heel rise tests, and work return), (2) cosmesis (length scar, cosmetic appearance), and (3) complications. We retrospectively reviewed 32 surgically treated patients with Achilles rupture: 17 with percutaneous repair and 15 with open repair. All patients followed a standardized rehabilitation protocol. The minimum followup was 6 months (mean, 18 months; range, 6-48 months). We observed similar values of plantar flexor strength, ROM, calf and ankle perimeter, and single heel raising test between the groups. Mean time to return to work was longer for patients who had open versus percutaneous repair (5.6 months versus 2.8 months). Mean scar length was greater in the open repair group (9.5 cm versus 2.9 cm). Cosmetic appearance was better in the percutaneous group. Two wound complications and one rerupture were found in the open repair group. One case of deep venous thrombosis occurred in the percutaneous repair group. All complications occurred before 6 months after surgery. We identified no patients with nerve injury. Percutaneous repair provides function similar to that achieved with open repair, with a better cosmetic appearance, a lower rate of wound complications, and no apparent increase in the risk of rerupture. Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Clinical and Radiological Outcomes Comparing Percutaneous Chevron-Akin Osteotomies vs Open Scarf-Akin Osteotomies for Hallux Valgus.

PubMed

Lai, Mun Chun; Rikhraj, Inderjeet Singh; Woo, Yew Lok; Yeo, William; Ng, Yung Chuan Sean; Koo, Kevin

2018-03-01

Minimally invasive surgeries have gained popularity due to less soft tissue trauma and better wound healing. To date, limited studies have compared the outcomes of percutaneous and open osteotomies. This study aims to investigate the clinical and radiological outcomes of percutaneous chevron-Akin osteotomies vs open scarf-Akin osteotomies at 24-month follow-up. We reviewed a prospectively collected database in a tertiary hospital hallux valgus registry. Twenty-nine feet that underwent a percutaneous technique were matched to 58 feet that underwent open scarf and Akin osteotomies. Clinical outcome measures assessed included visual analog scale (VAS) scores, American Orthopaedic Foot & Ankle Society Hallux Metatarsophalangeal-Interphalangeal score (AOFAS Hallux MTP-IP), and Short Form 36 (SF-36) Health Survey. Radiological outcomes included hallux valgus angle (HVA) and intermetatarsal angle (IMA). All patients were prospectively followed up at 6 and 24 months. Both groups showed comparable clinical and radiological outcomes at the 24-month follow-up. However, the percutaneous group demonstrated less pain in the perioperative period ( P < .001). There were significant differences in the change in HVA between the groups but comparable radiological outcomes in IMA at the 24-month follow-up. The percutaneous group demonstrated shorter length of operation ( P < .001). There were no complications in the percutaneous group but 3 wound complications in the open group. We conclude that clinical and radiological outcomes of third-generation percutaneous chevron-Akin osteotomies were comparable with open scarf and Akin osteotomies at 24 months but with significantly less perioperative pain, shorter length of operation, and less risk of wound complications. Level III, retrospective comparative series.

Association between percutaneous hemodynamic support device and survival from cardiac arrest in the state of Michigan.

PubMed

Pressman, Andrew; Sawyer, Kelly N; Devlin, William; Swor, Robert

2018-05-01

The role of circulatory support in the post-cardiac arrest period remains controversial. Our objective was to investigate the association between treatment with a percutaneous hemodynamic support device and outcome after admission for cardiac arrest. We performed a retrospective study of adult patients with admission diagnosis of cardiac arrest or ventricular fibrillation (VF) from the Michigan Inpatient Database, treated between July 1, 2010, and June 30, 2013. Patient demographics, clinical characteristics, treatments, and disposition were electronically abstracted based on ICD-9 codes at the hospital level. Mixed-effects logistic regression models were fit to test the effect of percutaneous hemodynamic support device defined as either percutaneous left ventricular assist device (pLVAD) or intra-aortic balloon pump (IABP) on survival. These models controlled for age, sex, VF, myocardial infarction (MI), and cardiogenic shock with hospital modeled as a random effect. A total of 103 hospitals contributed 4393 patients for analysis, predominately male (58.8%) with a mean age of 64.1years (SD 15.5). On univariate analysis, younger age, male sex, VF as the initial rhythm, acute MI, percutaneous coronary intervention, percutaneous hemodynamic support device, and absence of cardiogenic shock were associated with survival to discharge (each p<0.001). Mixed-effects logistic regressions revealed use of percutaneous hemodynamic support device was significantly associated with survival among all patients (OR 1.8 (1.28-2.54)), and especially in those with acute MI (OR 1.95 (1.31-2.93)) or cardiogenic shock (OR 1.96 (1.29-2.98)). Treatment with percutaneous hemodynamic support device in the post-arrest period may provide left ventricular support and improve outcome. Copyright © 2017 Elsevier Inc. All rights reserved.

Percutaneous laser disc decompression versus conventional microdiscectomy for patients with sciatica: Two-year results of a randomised controlled trial.

PubMed

Brouwer, Patrick A; Brand, Ronald; van den Akker-van Marle, M Elske; Jacobs, Wilco Ch; Schenk, Barry; van den Berg-Huijsmans, Annette A; Koes, Bart W; Arts, Mark A; van Buchem, M A; Peul, Wilco C

2017-06-01

Background Percutaneous laser disc decompression is a minimally invasive treatment, for lumbar disc herniation and might serve as an alternative to surgical management of sciatica. In a randomised trial with two-year follow-up we assessed the clinical effectiveness of percutaneous laser disc decompression compared to conventional surgery. Materials and methods This multicentre randomised prospective trial with a non-inferiority design, was carried out according to an intent-to-treat protocol with full institutional review board approval. One hundred and fifteen eligible surgical candidates, with sciatica from a disc herniation smaller than one-third of the spinal canal, were randomly allocated to percutaneous laser disc decompression ( n = 55) or conventional surgery ( n = 57). The main outcome measures for this trial were the Roland-Morris Disability Questionnaire for sciatica, visual analogue scores for back and leg pain and the patient's report of perceived recovery. Results The primary outcome measures showed no significant difference or clinically relevant difference between the two groups at two-year follow-up. The re-operation rate was 21% in the surgery group, which is relatively high, and with an even higher 52% in the percutaneous laser disc decompression group. Conclusion At two-year follow-up, a strategy of percutaneous laser disc decompression, followed by surgery if needed, resulted in non-inferior outcomes compared to a strategy of microdiscectomy. Although the rate of reoperation in the percutaneous laser disc decompression group was higher than expected, surgery could be avoided in 48% of those patients that were originally candidates for surgery. Percutaneous laser disc decompression, as a non-surgical method, could have a place in the treatment arsenal of sciatica caused by contained herniated discs.

Percutaneous implanted paddle lead for spinal cord stimulation: technical considerations and long-term follow-up.

PubMed

Kinfe, Thomas M; Schu, Stefan; Quack, Florian J; Wille, Christian; Vesper, Jan

2012-07-01

Spinal cord stimulation (SCS) is an established method for treatment of chronic pain. Cylindrical-type leads can be implanted percutaneously. In contrast, paddle leads (lamitrode) require more invasive surgery (i.e., laminotomy or laminectomy) for placement into the epidural space, thereby offering several advantages over percutaneous leads (octrode), including less lead migration and better paresthesia coverage. The goal of this study was to prospectively demonstrate the safety and efficacy of a percutaneous paddle lead for SCS. This prospective trial enrolled 81 patients. The mean age was 57 years (range 27-82 years) with an almost equal sex distribution (male 47%, female 53%). Most patients (90%) had failed back surgery syndrome combined with lower extremity pain and lower back pain. A percutaneous paddle lead was implanted using a novel introduction system for percutaneous implantation. All implantations were performed under local anesthesia. Prior to the final implantation of the impulse generator, all patients underwent seven days of trial stimulation with pain assessment using a visual analog scale (VAS). The median follow-up was 12 months. The data showed favorable clinical outcomes for paresthesia coverage and pain reduction (median VAS 8.4 vs. 2.3), with a risk profile comparable with known percutaneous techniques. Compared with the published data (2-22%), the lead migration rate in this study was low (2.5%). No perioperative complications occurred. This new, minimally invasive percutaneous paddle lead is effective and safe, with a low migration rate. Placement can be done under local anesthesia, allowing an intraoperative assessment of the paresthesia coverage in terms of pain relief. This approach is less invasive and offers a faster and more comfortable procedure compared with laminotomy or laminectomy. © 2012 International Neuromodulation Society.

Percutaneous versus traditional and paraspinal posterior open approaches for treatment of thoracolumbar fractures without neurologic deficit: a meta-analysis.

PubMed

Sun, Xiang-Yao; Zhang, Xi-Nuo; Hai, Yong

2017-05-01

This study evaluated differences in outcome variables between percutaneous, traditional, and paraspinal posterior open approaches for traumatic thoracolumbar fractures without neurologic deficit. A systematic review of PubMed, Cochrane, and Embase was performed. In this meta-analysis, we conducted online searches of PubMed, Cochrane, Embase using the search terms "thoracolumbar fractures", "lumbar fractures", ''percutaneous'', "minimally invasive", ''open", "traditional", "posterior", "conventional", "pedicle screw", "sextant", and "clinical trial". The analysis was performed on individual patient data from all the studies that met the selection criteria. Clinical outcomes were expressed as risk difference for dichotomous outcomes and mean difference for continuous outcomes with 95 % confidence interval. Heterogeneity was assessed using the χ 2 test and I 2 statistics. There were 4 randomized controlled trials and 14 observational articles included in this analysis. Percutaneous approach was associated with better ODI score, less Cobb angle correction, less Cobb angle correction loss, less postoperative VBA correction, and lower infection rate compared with open approach. Percutaneous approach was also associated with shorter operative duration, longer intraoperative fluoroscopy, less postoperative VAS, and postoperative VBH% in comparison with traditional open approach. No significant difference was found in Cobb angle correction, postoperative VBA, VBA correction loss, Postoperative VBH%, VBH correction loss, and pedicle screw misplacement between percutaneous approach and open approach. There was no significant difference in operative duration, intraoperative fluoroscopy, postoperative VAS, and postoperative VBH% between percutaneous approach and paraspianl approach. The functional and the radiological outcome of percutaneous approach would be better than open approach in the long term. Although trans-muscular spatium approach belonged to open fixation methods, it was strictly defined as less invasive approach, which provided less injury to the paraspinal muscles and better reposition effect.

Remote ischemic preconditioning and endothelial function in patients with acute myocardial infarction and primary PCI.

PubMed

Manchurov, Vladimir; Ryazankina, Nadezda; Khmara, Tatyana; Skrypnik, Dmitry; Reztsov, Roman; Vasilieva, Elena; Shpektor, Alexander

2014-07-01

Remote ischemic preconditioning by transient limb ischemia reduces myocardial ischemia-reperfusion injury in patients undergoing percutaneous coronary intervention. The aim of the study we report here was to assess the effect of remote ischemic preconditioning on endothelial function in patients with acute myocardial infarction who underwent primary percutaneous coronary intervention. Forty-eight patients with acute myocardial infarction were enrolled. All participants were randomly divided into 2 groups. In Group I (n = 23), remote ischemic preconditioning was performed before primary percutaneous coronary intervention (intermittent arm ischemia-reperfusion through 4 cycles of 5-minute inflation and 5-minute deflation of a blood-pressure cuff to 200 mm Hg). In Group II (n = 25), standard percutaneous coronary intervention without preconditioning was performed. We assessed endothelial function using the flow-mediated dilation test on baseline, then within 1-3 hours after percutaneous coronary intervention, and again on days 2 and 7 after percutaneous coronary intervention. The brachial artery flow-mediated dilation results were significantly higher on the first day after primary percutaneous coronary intervention in the preconditioning group (Group I) than in the control group (Group II) (12.1% vs 0.0%, P = .03, and 11.1% vs 6.3%, P = .016, respectively), and this difference remained on the seventh day (12.3% vs 7.4%, P = .0005, respectively). We demonstrated for the first time that remote ischemic preconditioning before primary percutaneous coronary intervention significantly improves endothelial function in patients with acute myocardial infarction, and this effect remains constant for at least a week. We suppose that the improvement of endothelial function may be one of the possible explanations of the effect of remote ischemic preconditioning. Copyright © 2014 Elsevier Inc. All rights reserved.

Percutaneous management of urolithiasis during pregnancy.

PubMed

Kavoussi, L R; Albala, D M; Basler, J W; Apte, S; Clayman, R V

1992-09-01

A total of 6 pregnant women with obstructing urinary calculi was managed by percutaneous nephrostomy drainage placed under ultrasound guidance with the patient under local anesthesia. All patients initially had relief of acute obstruction. However, occlusion of the percutaneous nephrostomy tubes with debris necessitated tube changes in 5 of 6 patients. In 2 patients recurrent nephrostomy tube obstruction, fever and pain led to percutaneous stone removal during pregnancy. In the remaining 4 patients the nephrostomy tubes were left indwelling through delivery. During the postpartum period 3 patients successfully underwent ureteroscopic stone extraction and 1 passed the stone spontaneously. Bacteriuria developed in each patient despite the use of preventive antibiotics. All 6 women had uncomplicated vaginal deliveries of healthy newborns and are currently asymptomatic with no evidence of obstruction. Percutaneous drainage of an acutely obstructed kidney in a pregnant woman is an effective temporizing alternative to ureteral stent placement until definitive treatment can be performed.

Successful treatment of tumor-induced osteomalacia with CT-guided percutaneous ethanol and cryoablation.

PubMed

Tutton, Sean; Olson, Erik; King, David; Shaker, Joseph L

2012-10-01

Tumor-induced osteomalacia is a rare condition usually caused by benign mesenchymal tumors. When the tumor can be found, patients are usually managed by wide excision of the tumor. We report a 51-yr-old male with clinical and biochemical evidence of tumor-induced osteomalacia caused by a mesenchymal tumor in the right iliac bone. He declined surgery and appears to have been successfully managed by computed tomography-guided percutaneous ethanol ablation and percutaneous cryoablation. Our patient appears to have had an excellent clinical and biochemical response to computed tomography-guided percutaneous ethanol ablation and percutaneous cryoablation. We found one prior case of image-guided ablation using radiofrequency ablation for tumor-induced osteomalacia. Although the standard treatment for tumor-induced osteomalacia is wide excision of the tumor, image-guided ablation may be an option in patients who cannot have appropriate surgery or who decline surgery.

Dynamic stability experiment of Maglev systems

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

Cai, Y.; Mulcahy, T.M.; Chen, S.S.

1995-04-01

This report summarizes the research performed on Maglev vehicle dynamic stability at Argonne National Laboratory during the past few years. It also documents magnetic-force data obtained from both measurements and calculations. Because dynamic instability is not acceptable for any commercial Maglev system, it is important to consider this phenomenon in the development of all Maglev systems. This report presents dynamic stability experiments on Maglev systems and compares their numerical simulation with predictions calculated by a nonlinear dynamic computer code. Instabilities of an electrodynamic system (EDS)-type vehicle model were obtained from both experimental observations and computer simulations for a five-degree-of-freedom Maglevmore » vehicle moving on a guideway consisting of double L-shaped aluminum segments attached to a rotating wheel. The experimental and theoretical analyses developed in this study identify basic stability characteristics and future research needs of Maglev systems.« less

Dynamic stability of repulsive-force maglev suspension systems

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

Cai, Y.; Rote, D.M.; Mulcahy, T.M.

1996-11-01

This report summarizes the research performed on maglev vehicle dynamic stability at Argonne National Laboratory during the past few years. It also documents both measured and calculated magnetic-force data. Because dynamic instability is not acceptable for any commercial maglev system, it is important to consider this phenomenon in the development of all maglev systems. This report presents dynamic stability experiments on maglev systems and compares the results with predictions calculated by a nonlinear-dynamics computer code. Instabilities of an electrodynamic-suspension system type vehicle model were obtained by experimental observation and computer simulation of a five-degree-of-freedom maglev vehicle moving on a guidewaymore » that consists of a pair of L-shaped aluminum conductors attached to a rotating wheel. The experimental and theoretical analyses developed in this study identify basic stability characteristics and future research needs of maglev systems.« less

Dynamic stability and bifurcation analysis in fractional thermodynamics

NASA Astrophysics Data System (ADS)

Béda, Péter B.

2018-02-01

In mechanics, viscoelasticity was the first field of applications in studying geomaterials. Further possibilities arise in spatial non-locality. Non-local materials were already studied in the 1960s by several authors as a part of continuum mechanics and are still in focus of interest because of the rising importance of materials with internal micro- and nano-structure. When material instability gained more interest, non-local behavior appeared in a different aspect. The problem was concerned to numerical analysis, because then instability zones exhibited singular properties for local constitutive equations. In dynamic stability analysis, mathematical aspects of non-locality were studied by using the theory of dynamic systems. There the basic set of equations describing the behavior of continua was transformed to an abstract dynamic system consisting of differential operators acting on the perturbation field variables. Such functions should satisfy homogeneous boundary conditions and act as indicators of stability of a selected state of the body under consideration. Dynamic systems approach results in conditions for cases, when the differential operators have critical eigenvalues of zero real parts (dynamic stability or instability conditions). When the critical eigenvalues have non-trivial eigenspace, the way of loss of stability is classified as a typical (or generic) bifurcation. Our experiences show that material non-locality and the generic nature of bifurcation at instability are connected, and the basic functions of the non-trivial eigenspace can be used to determine internal length quantities of non-local mechanics. Fractional calculus is already successfully used in thermo-elasticity. In the paper, non-locality is introduced via fractional strain into the constitutive relations of various conventional types. Then, by defining dynamic systems, stability and bifurcation are studied for states of thermo-mechanical solids. Stability conditions and genericity conditions are presented for constitutive relations under consideration.

Steady-State Computation of Constant Rotational Rate Dynamic Stability Derivatives

NASA Technical Reports Server (NTRS)

Park, Michael A.; Green, Lawrence L.

2000-01-01

Dynamic stability derivatives are essential to predicting the open and closed loop performance, stability, and controllability of aircraft. Computational determination of constant-rate dynamic stability derivatives (derivatives of aircraft forces and moments with respect to constant rotational rates) is currently performed indirectly with finite differencing of multiple time-accurate computational fluid dynamics solutions. Typical time-accurate solutions require excessive amounts of computational time to complete. Formulating Navier-Stokes (N-S) equations in a rotating noninertial reference frame and applying an automatic differentiation tool to the modified code has the potential for directly computing these derivatives with a single, much faster steady-state calculation. The ability to rapidly determine static and dynamic stability derivatives by computational methods can benefit multidisciplinary design methodologies and reduce dependency on wind tunnel measurements. The CFL3D thin-layer N-S computational fluid dynamics code was modified for this study to allow calculations on complex three-dimensional configurations with constant rotation rate components in all three axes. These CFL3D modifications also have direct application to rotorcraft and turbomachinery analyses. The modified CFL3D steady-state calculation is a new capability that showed excellent agreement with results calculated by a similar formulation. The application of automatic differentiation to CFL3D allows the static stability and body-axis rate derivatives to be calculated quickly and exactly.

The Photodynamic Bone Stabilization System: a minimally invasive, percutaneous intramedullary polymeric osteosynthesis for simple and complex long bone fractures.

PubMed

Vegt, Paul; Muir, Jeffrey M; Block, Jon E

2014-01-01

The treatment of osteoporotic long bone fractures is difficult due to diminished bone density and compromised biomechanical integrity. The majority of osteoporotic long bone fractures occur in the metaphyseal region, which poses additional problems for surgical repair due to increased intramedullary volume. Treatment with internal fixation using intramedullary nails or plating is associated with poor clinical outcomes in this patient population. Subsequent fractures and complications such as screw pull-out necessitate additional interventions, prolonging recovery and increasing health care costs. The Photodynamic Bone Stabilization System (PBSS) is a minimally invasive surgical technique that allows clinicians to repair bone fractures using a light-curable polymer contained within an inflatable balloon catheter, offering a new treatment option for osteoporotic long bone fractures. The unique polymer compound and catheter application provides a customizable solution for long bone fractures that produces internal stability while maintaining bone length, rotational alignment, and postsurgical mobility. The PBSS has been utilized in a case series of 41 fractures in 33 patients suffering osteoporotic long bone fractures. The initial results indicate that the use of the light-cured polymeric rod for this patient population provides excellent fixation and stability in compromised bone, with a superior complication profile. This paper describes the clinical uses, procedural details, indications for use, and the initial clinical findings of the PBSS.

The Photodynamic Bone Stabilization System: a minimally invasive, percutaneous intramedullary polymeric osteosynthesis for simple and complex long bone fractures

PubMed Central

Vegt, Paul; Muir, Jeffrey M; Block, Jon E

2014-01-01

The treatment of osteoporotic long bone fractures is difficult due to diminished bone density and compromised biomechanical integrity. The majority of osteoporotic long bone fractures occur in the metaphyseal region, which poses additional problems for surgical repair due to increased intramedullary volume. Treatment with internal fixation using intramedullary nails or plating is associated with poor clinical outcomes in this patient population. Subsequent fractures and complications such as screw pull-out necessitate additional interventions, prolonging recovery and increasing health care costs. The Photodynamic Bone Stabilization System (PBSS) is a minimally invasive surgical technique that allows clinicians to repair bone fractures using a light-curable polymer contained within an inflatable balloon catheter, offering a new treatment option for osteoporotic long bone fractures. The unique polymer compound and catheter application provides a customizable solution for long bone fractures that produces internal stability while maintaining bone length, rotational alignment, and postsurgical mobility. The PBSS has been utilized in a case series of 41 fractures in 33 patients suffering osteoporotic long bone fractures. The initial results indicate that the use of the light-cured polymeric rod for this patient population provides excellent fixation and stability in compromised bone, with a superior complication profile. This paper describes the clinical uses, procedural details, indications for use, and the initial clinical findings of the PBSS. PMID:25540600

Protocol for the China PEACE (Patient-centered Evaluative Assessment of Cardiac Events) retrospective study of coronary catheterisation and percutaneous coronary intervention.

PubMed

Li, Jing; Dharmarajan, Kumar; Li, Xi; Lin, Zhenqiu; Normand, Sharon-Lise T; Krumholz, Harlan M; Jiang, Lixin

2014-03-07

During the past decade, the volume of percutaneous coronary intervention (PCI) in China has risen by more than 20-fold. Yet little is known about patterns of care and outcomes across hospitals, regions and time during this period of rising cardiovascular disease and dynamic change in the Chinese healthcare system. Using the China PEACE (Patient-centered Evaluative Assessment of Cardiac Events) research network, the Retrospective Study of Coronary Catheterisation and Percutaneous Coronary Intervention (China PEACE-Retrospective CathPCI Study) will examine a nationally representative sample of 11 900 patients who underwent coronary catheterisation or PCI at 55 Chinese hospitals during 2001, 2006 and 2011. We selected patients and study sites using a two-stage cluster sampling design with simple random sampling stratified within economical-geographical strata. A central coordinating centre will monitor data quality at the stages of case ascertainment, medical record abstraction and data management. We will examine patient characteristics, diagnostic testing patterns, procedural treatments and in-hospital outcomes, including death, complications of treatment and costs of hospitalisation. We will additionally characterise variation in treatments and outcomes by patient characteristics, hospital, region and study year. The China PEACE collaboration is designed to translate research into improved care for patients. The study protocol was approved by the central ethics committee at the China National Center for Cardiovascular Diseases (NCCD) and collaborating hospitals. Findings will be shared with participating hospitals, policymakers and the academic community to promote quality monitoring, quality improvement and the efficient allocation and use of coronary catheterisation and PCI in China. http://www.clinicaltrials.gov (NCT01624896).

Single-Centre Experience with Percutaneous Cryoablation of Breast Cancer in 23 Consecutive Non-surgical Patients

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

Cazzato, Roberto Luigi, E-mail: r.cazzato@unicampus.it; Lara, Christine Tunon de, E-mail: c.tunondelara@bordeaux.unicancer.fr; Buy, Xavier, E-mail: x.buy@bordeaux.unicancer.fr

AimTo present our single-centre prospective experience on the use of cryoablation (CA) applied to treat primary breast cancer (BC) in a cohort of patients unsuitable for surgical treatment.Materials and MethodsTwenty-three consecutive post-menopausal female patients (median age 85 years; range 56–96) underwent percutaneous CA of unifocal, biopsy-proven BC, under ultrasound/computed tomography (US/CT) guidance. Clinical and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) follow-ups were systematically scheduled at 3, 12, 18 and 24 months. Local tumour control was assessed by comparing baseline and follow-up DCE-MRI.ResultsTwenty-three BC (median size 14 mm) were treated under local anaesthesia (78.3 %) or local anaesthesia and conscious sedation (21.7 %). Median number ofmore » cryo-probes applied per session was 2.0. A “dual-freezing” protocol was applied for the first ten patients and a more aggressive “triple-freezing” protocol for the remaining 13. Median follow-up was 14.6 months. Five patients recurred during follow-up and two were successfully re-treated with CA. Five patients presented immediate CA-related complications: four hematomas evolved uneventfully at 3-month follow-up and one skin burn resulted in skin inflammation and skin retraction at 3 and 12 months, respectively.ConclusionsPercutaneous CA is safe and well tolerated for non-resected elderly BC patients. Procedures can be proposed under local anaesthesia only. Given the insulation properties of the breast gland, aggressive CA protocols are required. Prospective studies are needed to better understand the potential role of CA in the local treatment of early BC.« less

Protocol for the China PEACE (Patient-centered Evaluative Assessment of Cardiac Events) retrospective study of coronary catheterisation and percutaneous coronary intervention

PubMed Central

Li, Jing; Dharmarajan, Kumar; Li, Xi; Lin, Zhenqiu; Normand, Sharon-Lise T; Krumholz, Harlan M; Jiang, Lixin

2014-01-01

Introduction During the past decade, the volume of percutaneous coronary intervention (PCI) in China has risen by more than 20-fold. Yet little is known about patterns of care and outcomes across hospitals, regions and time during this period of rising cardiovascular disease and dynamic change in the Chinese healthcare system. Methods and analysis Using the China PEACE (Patient-centered Evaluative Assessment of Cardiac Events) research network, the Retrospective Study of Coronary Catheterisation and Percutaneous Coronary Intervention (China PEACE-Retrospective CathPCI Study) will examine a nationally representative sample of 11 900 patients who underwent coronary catheterisation or PCI at 55 Chinese hospitals during 2001, 2006 and 2011. We selected patients and study sites using a two-stage cluster sampling design with simple random sampling stratified within economical-geographical strata. A central coordinating centre will monitor data quality at the stages of case ascertainment, medical record abstraction and data management. We will examine patient characteristics, diagnostic testing patterns, procedural treatments and in-hospital outcomes, including death, complications of treatment and costs of hospitalisation. We will additionally characterise variation in treatments and outcomes by patient characteristics, hospital, region and study year. Ethics and dissemination The China PEACE collaboration is designed to translate research into improved care for patients. The study protocol was approved by the central ethics committee at the China National Center for Cardiovascular Diseases (NCCD) and collaborating hospitals. Findings will be shared with participating hospitals, policymakers and the academic community to promote quality monitoring, quality improvement and the efficient allocation and use of coronary catheterisation and PCI in China. Registration details http://www.clinicaltrials.gov (NCT01624896). PMID:24607563

In vitro determination of transdermal permeation of synthetic musks and estimated dermal uptake through usage of personal care products.

PubMed

Zhang, Xiaolan; Yu, Yuling; Gu, Yue; Li, Xiaojing; Zhang, Xinyu; Yu, Yingxin

2017-04-01

Synthetic musks, chemical constituents of personal care products, enter the human body through dermal contact. Elucidation of the mechanisms underlying transdermal permeation of synthetic musks should enhance our understanding of their uptake and distribution in human skin and allow accurate evaluation of associated human exposure. Here, the transdermal permeation dynamics and distribution of galaxolide (HHCB) and tonalide (AHTN) were investigated using an in vitro skin diffusion model. The transdermal permeation amounts of HHCB and AHTN increased rapidly during the first 6 h. The applied HHCB and AHTN amounts did not affect percutaneous absorption rates. HHCB and AHTN remained primarily in the stratum corneum, accounting for 70.0% and 70.3% of the totals during the 24-h period, respectively. The percutaneous absorption rate of both chemicals was ∼11%. HHCB, AHTN, musk ketone, musk xylene, and Musk-T were detected in 29 personal care products. The average total concentrations of the musks were 3990, 54.0, 17.7, and 9.8 μg g -1 in perfume, shampoo, lotion, and shower gel, respectively. Among the four product categories, HHCB was dominant (57.4%-99.6%), followed by AHTN. The data clearly indicate that polycyclic and nitro musks are most commonly used in personal care products. The total estimated dermal intake (51.6 μg kg -1 bw  day -1 ) was markedly higher than total dermal uptake (5.9 μg kg -1 bw  day -1 ) when percutaneous absorption rates of the chemicals were added into the calculation. Uptake of HHCB and AHTN via dermal contact of personal care products was significantly higher than that from dust inhalation calculated according to earlier literature data. Copyright © 2017 Elsevier Ltd. All rights reserved.

Percutaneous Tricuspid Valve Regurgitation Repair With the MitraClip Device Using an Edge-to-Edge Bicuspidization Technique.

PubMed

Gafoor, Sameer; Petrescu, O Madalina; Lehr, Eric J; Puls, Charles; Zhang, Ming; Petersen, John L; Olsen, John V; Penev, Irina; Agrawal, Mayank; Sharma, Rahul; Barnhart, Glenn

2017-03-01

Patients who present with both severe mitral and tricuspid regurgitation who are symptomatic despite optimal medical therapy and at prohibitive risk for surgery pose a significant therapeutic challenge. The MitraClip device (Abbott Vascular) is approved for percutaneous mitral valve repair in high-risk and non-operative patients, and has also been used for tricuspid valve repair. Imaging support for percutaneous edge-to-edge tricuspid valve repair has not been reported and is a vital part of the procedure. Here, we present a periprocedural imaging strategy for percutaneous tricuspid valve repair with the MitraClip device using a bicuspidization technique.

Splenic injury during percutaneous nephrolithotomy.

PubMed

Thomas, Anil A; Pierce, Gregory; Walsh, R Matthew; Sands, Mark; Noble, Mark

2009-01-01

Injury to the spleen is a recognized complication during percutaneous renal access due to the close anatomical relationship of the spleen and the left kidney. However, transsplenic renal access is a rare complication of percutaneous nephrolithotomy and can also result in considerable morbidity, often requiring emergent splenectomy. We present our experience with splenic injury during percutaneous nephrolithotomy managed conservatively with the use of a collagen-thrombin hemostatic sealant (D-Stat; Vascular Solutions, Inc., Minneapolis, MN) after delayed removal of the nephrostomy tubes. The patient had an uneventful recovery and was discharged home on postoperative day 6. In select hemodynamically stable patients, nonoperative management with the adjunctive use of hemostatic sealants may be considered.

Safety of pediatric percutaneous liver biopsy performed by interventional radiologists.

PubMed

Potter, Carol; Hogan, Mark J; Henry-Kendjorsky, Katherine; Balint, Jane; Barnard, John A

2011-08-01

National data suggest that pediatric percutaneous liver biopsy is increasingly being performed by interventional radiologists rather than pediatric gastroenterologists. The objective of the present report is to describe the safety and effectiveness of percutaneous liver biopsy performed by interventional radiologists in a large cohort of children and to compare the results with the existing literature on biopsies performed by pediatric gastroenterologists. The medical records of 249 children undergoing ultrasound-guided percutaneous liver biopsy by interventional radiologists were reviewed for adverse events and success of obtaining tissue. Two hundred ninety-four biopsies were reviewed. There were no deaths. There were 2 instances of a 2-g or greater drop in hemoglobin following biopsy, neither of which was associated with clinical signs of hemorrhage. A small, asymptomatic pneumothorax quickly resolved without treatment. One patient developed Klebsiella sepsis 48  hours after biopsy. In all but 1 case, an adequate sample size was obtained. This low incidence of adverse events compares favorably with existing published reports of morbidity and mortality following percutaneous liver biopsy performed by pediatric gastroenterologists. Ultrasound-guided percutaneous liver biopsy performed by experienced pediatric interventional radiologists in a children's hospital setting is as safe and effective as biopsy performed by pediatric gastroenterologists.

A novel vacuum assisted closure therapy model for use with percutaneous devices.

PubMed

Cook, Saranne J; Nichols, Francesca R; Brunker, Lucille B; Bachus, Kent N

2014-06-01

Long-term maintenance of a dermal barrier around a percutaneous prosthetic device remains a common clinical problem. A technique known as Negative Pressure Wound Therapy (NPWT) uses negative pressure to facilitate healing of impaired and complex soft tissue wounds. However, the combination of using negative pressure with percutaneous prosthetic devices has not been investigated. The goal of this study was to develop a methodology to apply negative pressure to the tissues surrounding a percutaneous device in an animal model; no tissue healing outcomes are presented. Specifically, four hairless rats received percutaneous porous coated titanium devices implanted on the dorsum and were bandaged with a semi occlusive film dressing. Two of these animals received NPWT; two animals received no NPWT and served as baseline controls. Over a 28-day period, both the number of dressing changes required between the two groups as well as the pressures were monitored. Negative pressures were successfully applied to the periprosthetic tissues in a clinically relevant range with a manageable number of dressing changes. This study provides a method for establishing, maintaining, and quantifying controlled negative pressures to the tissues surrounding percutaneous devices using a small animal model. Published by Elsevier Ltd.

Use of 3 mm percutaneous instruments with 5 mm end effectors during different laparoscopic procedures.

PubMed

David, Giulia; Boni, Luigi; Rausei, Stefano; Cassinotti, Elisa; Dionigi, Gianlorenzo; Rovera, Francesca; Spampatti, Sebastiano; Colombo, Elisabetta Marta; Dionigi, Renzo

2013-01-01

With a recent focus on minimizing the visibility of scars, new techniques have been developed. Minilaparoscopy reemerged as an attractive option for surgery as it limits tissue trauma, reduces post-operative pain and improves cosmesis. This study was designed to describe our experience with percutaneous trocarless 3 mm instruments used in combination with standard 5 mm and 10 mm laparoscopic instruments in different general surgery procedures. We used the PSS (Percutaneous Surgical Set, Ethicon Endo surgery, Cincinnati, OH, USA) in different surgical procedures as accessory instruments in combination with standard 5 mm and 10 mm standard laparoscopic instruments. The use of percutaneous instruments was safe and feasible in all performed procedures. The surgical technique was not modified. The percutaneous instruments can assure a good grip and can be used for traction and counter-traction. No complications have been described. No pain at the site of insertion has been reported. The skin, muscle and peritoneal defects were smaller than with the 3 mm laparoscopic traditional instruments. Percutaneous approach seems to be a good option in general surgery in terms of efficiency, offering better cosmetic results and good pain control. Copyright © 2013 Elsevier Ltd and Surgical Associates Ltd. All rights reserved.

Percutaneous drainage in conservative therapy for perforated gastroduodenal ulcers.

PubMed

Oida, Takatsugu; Kano, Hisao; Mimatsu, Kenji; Kawasaki, Atsushi; Kuboi, Youichi; Fukino, Nobutada; Kida, Kazutoshi; Amano, Sadao

2012-01-01

The management of peptic ulcers has dramatically changed and the incidence of elective surgery for gastroduodenal peptic ulcers has markedly decreased; hence, the incidence of emergency surgery for perforated peptic ulcers has slightly increased. In select cases, conservative therapy can be used as an alternative for treating perforated gastroduodenal ulcers. In this study, we evaluated the efficacy of percutaneous abdominal drainage for the conservative treatment of perforated gastroduodenal ulcers. We retrospectively studied 51 patients who had undergone conservative therapy for perforated gastroduodenal ulcers. These patients were divided into 2 groups on the basis of the initial treatment with conservative therapy with or without percutaneous drainage: group PD included patients who had undergone percutaneous drainage and group NPD, patients who had undergone non-percutaneous drainage. In the PD group, 14.3% (n=3) of the patients did not respond to conservative therapy, while this value was 43.3% (n=13) in the NPD group. The 2 groups differed significantly with respect to conversion from conservative therapy to surgery (p<0.0352). Conservative therapy for perforated gastroduodenal ulcers should be performed only in the case of patients meeting the required criteria; its combination with percutaneous intraperitoneal drainage is effective as initial conservative therapy.

Percutaneous trans-papillary elimination of common bile duct stones using an existing gallbladder drain for access.

PubMed

Atar, Eli; Neiman, Chaim; Ram, Eduard; Almog, Mazal; Gadiel, Itai; Belenky, Alexander

2012-06-01

The presence of stones in the common bile duct (CBD) may cause complications such as obstructing jaundice or ascending cholangitis, and the stones should be removed. To assess the efficacy of percutaneous elimination of CBD stones from the gallbladder through the papilla. During a 4 year period, six patients (five men and one woman, mean age 71.5 years) who had CBD stones and an existing gallbladder drain underwent percutaneous stone push into the duodenum after balloon dilatation of the papilla, with a diameter equal to that of the largest stone. Access into the CBD was from the gallbladder, using an already existing percutaneous gallbladder drain (cholecystostomy tube). Each patient had one to three CBD stones measuring 7-14 mm. Successful CBD stone elimination into the duodenum was achieved in five of the six patients. The single failure occurred in a patient with choledochal diverticulum, who was operated successfully. There were no major or minor complications during or after the procedures. Trans-cholecystic CBD stone elimination is a safe and feasible percutaneous technique that utilizes existing tracts, thus obviating the need to create new percutaneous access. This procedure can replace endoscopic or surgical CBD exploration.

Structural stability of nonlinear population dynamics.

PubMed

Cenci, Simone; Saavedra, Serguei

2018-01-01

In population dynamics, the concept of structural stability has been used to quantify the tolerance of a system to environmental perturbations. Yet, measuring the structural stability of nonlinear dynamical systems remains a challenging task. Focusing on the classic Lotka-Volterra dynamics, because of the linearity of the functional response, it has been possible to measure the conditions compatible with a structurally stable system. However, the functional response of biological communities is not always well approximated by deterministic linear functions. Thus, it is unclear the extent to which this linear approach can be generalized to other population dynamics models. Here, we show that the same approach used to investigate the classic Lotka-Volterra dynamics, which is called the structural approach, can be applied to a much larger class of nonlinear models. This class covers a large number of nonlinear functional responses that have been intensively investigated both theoretically and experimentally. We also investigate the applicability of the structural approach to stochastic dynamical systems and we provide a measure of structural stability for finite populations. Overall, we show that the structural approach can provide reliable and tractable information about the qualitative behavior of many nonlinear dynamical systems.

Structural stability of nonlinear population dynamics

NASA Astrophysics Data System (ADS)

Cenci, Simone; Saavedra, Serguei

2018-01-01

In population dynamics, the concept of structural stability has been used to quantify the tolerance of a system to environmental perturbations. Yet, measuring the structural stability of nonlinear dynamical systems remains a challenging task. Focusing on the classic Lotka-Volterra dynamics, because of the linearity of the functional response, it has been possible to measure the conditions compatible with a structurally stable system. However, the functional response of biological communities is not always well approximated by deterministic linear functions. Thus, it is unclear the extent to which this linear approach can be generalized to other population dynamics models. Here, we show that the same approach used to investigate the classic Lotka-Volterra dynamics, which is called the structural approach, can be applied to a much larger class of nonlinear models. This class covers a large number of nonlinear functional responses that have been intensively investigated both theoretically and experimentally. We also investigate the applicability of the structural approach to stochastic dynamical systems and we provide a measure of structural stability for finite populations. Overall, we show that the structural approach can provide reliable and tractable information about the qualitative behavior of many nonlinear dynamical systems.

Percutaneous Transsplenic Access to the Portal Vein for Management of Vascular Complication in Patients with Chronic Liver Disease

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

Chu, Hee Ho; Kim, Hyo-Cheol, E-mail: angiointervention@gmail.com; Jae, Hwan Jun

Purpose: To evaluate the safety and feasibility of percutaneous transsplenic access to the portal vein for management of vascular complication in patients with chronic liver diseases. Methods: Between Sept 2009 and April 2011, percutaneous transsplenic access to the portal vein was attempted in nine patients with chronic liver disease. Splenic vein puncture was performed under ultrasonographic guidance with a Chiba needle, followed by introduction of a 4 to 9F sheath. Four patients with hematemesis or hematochezia underwent variceal embolization. Another two patients underwent portosystemic shunt embolization in order to improve portal venous blood flow. Portal vein recanalization was attempted inmore » three patients with a transplanted liver. The percutaneous transsplenic access site was closed using coils and glue. Results: Percutaneous transsplenic splenic vein catheterization was performed successfully in all patients. Gastric or jejunal varix embolization with glue and lipiodol mixture was performed successfully in four patients. In two patients with a massive portosystemic shunt, embolization of the shunting vessel with a vascular plug, microcoils, glue, and lipiodol mixture was achieved successfully. Portal vein recanalization was attempted in three patients with a transplanted liver; however, only one patient was treated successfully. Complete closure of the percutaneous transsplenic tract was achieved using coils and glue without bleeding complication in all patients. Conclusion: Percutaneous transsplenic access to the portal vein can be an alternative route for portography and further endovascular management in patients for whom conventional approaches are difficult or impossible.« less

Evolving biopsy techniques for the diagnosis of neuroblastoma in children.

PubMed

Campagna, Giovanni; Rosenfeld, Eric; Foster, Jennifer; Vasudevan, Sanjeev; Nuchtern, Jed; Kim, Eugene; Commander, Sarah; Naik-Mathuria, Bindi

2018-04-14

To compare the adequacy and safety of percutaneous core needle biopsy and surgical wedge biopsy of neuroblastoma in children. A retrospective review of patients who underwent biopsy for intermediate- or high-risk neuroblastoma at our institution between 2011 and 2015 was performed (recent cohort). Procedure details and outcomes were collected and analyzed using descriptive statistics and Wilcoxon rank tests; P < 0.05 was considered significant. Published data from 2002 to 2010 were compared (historic cohort). Since 2011, percutaneous, ultrasound-guided, core needle biopsy has been more commonly utilized (47% (16/34) recent vs. 25% (7/28) historic; P = 0.07), and the number of core needle samples increased from median 7 (historic) to 25 (recent). Complications decreased (21% (7/34) recent vs. 64% (18/28) historic; P < 0.01). Biopsy adequacy in the recent cohort was similar (94% percutaneous vs. 89% surgical; P = 1.00), which is improved from the historic cohort (71% percutaneous vs. 100% surgical; P = 0.06). Larger tumors were more likely to have a percutaneous biopsy (82 ± 37 cm percutaneous vs. 47 ± 29 cm surgical; P = 0.04). When multiple cores are obtained, percutaneous core needle biopsy is adequate for complete tissue diagnosis of neuroblastoma and can be safely performed. This can be considered as an alternative to open surgical biopsy. Treatment Study. III. Copyright © 2018 Elsevier Inc. All rights reserved.

Microendoscopic stereotactic-guided percutaneous radiofrequency trigeminal nucleotractotomy.

PubMed

Teixeira, Manoel Jacobsen; de Almeida, Fabrício Freitas; de Oliveira, Ywzhe Sifuentes Almeida; Fonoff, Erich Talamoni

2012-02-01

Over the past few decades, various authors have performed open or stereotactic trigeminal nucleotractotomy for the treatment of neuropathic facial pain resistant to medical treatment. Stereotactic procedures can be performed percutaneously under local anesthesia, allowing intraoperative neurological examination as a method for target refinement. However, blind percutaneous procedures in the region of the atlantooccipital transition carry a considerably high risk of vascular injuries that may bring prohibitive neurological deficit or even death. To avoid such complications, the authors present the first clinical use of microendoscopy to assist percutaneous radiofrequency trigeminal nucleotractotomy. The aim of this article is to demonstrate intradural microendoscopic visualization of the medulla oblongata through an atlantooccipital percutaneous approach. The authors present a case of severe postherpetic facial neuralgia in a patient who underwent the procedure and had satisfactory results. Stereotactic computational image planning for targeting the spinal trigeminal tract and nucleus in the posterolateral medulla was performed, allowing for an accurate percutaneous approach. Immediately before radiofrequency electrode insertion, a fine endoscope was introduced to visualize the structures in the cisterna magna. Microendoscopic visualization offered clear identification of the pial surface of the medulla oblongata and its blood vessels, the arachnoid membrane, cranial nerve rootlets and their entry zone, and larger vessels such as the vertebral arteries and the branches of the posterior inferior cerebellar artery. The initial application of this technique suggests that percutaneous microendoscopy may be useful for particular manipulation of the medulla oblongata, increasing the safety of the procedure and likely improving its effectiveness.

Cosmetics-triggered percutaneous remote control of transgene expression in mice.

PubMed

Wang, Hui; Ye, Haifeng; Xie, Mingqi; Daoud El-Baba, Marie; Fussenegger, Martin

2015-08-18

Synthetic biology has significantly advanced the rational design of trigger-inducible gene switches that program cellular behavior in a reliable and predictable manner. Capitalizing on genetic componentry, including the repressor PmeR and its cognate operator OPmeR, that has evolved in Pseudomonas syringae pathovar tomato DC3000 to sense and resist plant-defence metabolites of the paraben class, we have designed a set of inducible and repressible mammalian transcription-control devices that could dose-dependently fine-tune transgene expression in mammalian cells and mice in response to paraben derivatives. With an over 60-years track record as licensed preservatives in the cosmetics industry, paraben derivatives have become a commonplace ingredient of most skin-care products including shower gels, cleansing toners and hand creams. As parabens can rapidly reach the bloodstream of mice following topical application, we used this feature to percutaneously program transgene expression of subcutaneous designer cell implants using off-the-shelf commercial paraben-containing skin-care cosmetics. The combination of non-invasive, transdermal and orthogonal trigger-inducible remote control of transgene expression may provide novel opportunities for dynamic interventions in future gene and cell-based therapies. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Cosmetics-triggered percutaneous remote control of transgene expression in mice

PubMed Central

Wang, Hui; Ye, Haifeng; Xie, Mingqi; Daoud El-Baba, Marie; Fussenegger, Martin

2015-01-01

Synthetic biology has significantly advanced the rational design of trigger-inducible gene switches that program cellular behavior in a reliable and predictable manner. Capitalizing on genetic componentry, including the repressor PmeR and its cognate operator OPmeR, that has evolved in Pseudomonas syringae pathovar tomato DC3000 to sense and resist plant-defence metabolites of the paraben class, we have designed a set of inducible and repressible mammalian transcription-control devices that could dose-dependently fine-tune transgene expression in mammalian cells and mice in response to paraben derivatives. With an over 60-years track record as licensed preservatives in the cosmetics industry, paraben derivatives have become a commonplace ingredient of most skin-care products including shower gels, cleansing toners and hand creams. As parabens can rapidly reach the bloodstream of mice following topical application, we used this feature to percutaneously program transgene expression of subcutaneous designer cell implants using off-the-shelf commercial paraben-containing skin-care cosmetics. The combination of non-invasive, transdermal and orthogonal trigger-inducible remote control of transgene expression may provide novel opportunities for dynamic interventions in future gene and cell-based therapies. PMID:25943548

Learning and Understanding System Stability Using Illustrative Dynamic Texture Examples

ERIC Educational Resources Information Center

Liu, Huaping; Xiao, Wei; Zhao, Hongyan; Sun, Fuchun

2014-01-01

System stability is a basic concept in courses on dynamic system analysis and control for undergraduate students with computer science backgrounds. Typically, this was taught using a simple simulation example of an inverted pendulum. Unfortunately, many difficult issues arise in the learning and understanding of the concepts of stability,…

Mathematical modelling and linear stability analysis of laser fusion cutting

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

Hermanns, Torsten; Schulz, Wolfgang; Vossen, Georg

A model for laser fusion cutting is presented and investigated by linear stability analysis in order to study the tendency for dynamic behavior and subsequent ripple formation. The result is a so called stability function that describes the correlation of the setting values of the process and the process’ amount of dynamic behavior.

A review of dynamic stability of repulsive-force maglev suspension systems

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

Cai, Y.; Rote, D.M.

1998-07-01

Vehicle dynamics and the need to satisfy ride quality requirements have long been recognized as crucial to the commercial success of passenger-carrying transportation systems. Design concepts for maglev systems are no exception. Early maglev investigators and designers were well aware of the importance of ride quality and took care to ensure that their designs would meet acceptable ride quality standards. In contrast, the dynamic stability of electrodynamic suspension (EDS) systems, which has obvious implications for system safety and cost as well as for ride quality, has not received nearly as much attention. Because of the well-known under-damped nature of EDSmore » suspension systems and the observation of instabilities in laboratory-scale model systems, it is prudent to develop a better understanding of vehicle stability characteristics. The work reported in this was undertaken with the intention of summarizing information that has been accumulated worldwide and that is relevant to dynamic stability of repulsive-force maglev suspension systems, assimilating that information, and gaining an understanding of the factors that influence that stability. Included in the paper is a discussion and comparison of results acquired from some representative tests of large-scale vehicles on linear test tracks, together with analytical and laboratory-scale investigations of stability and dynamics of EDS systems. This paper will also summarize the R and D activities at Argonne National Laboratory (ANL) since 1991 to study the nature of the forces that are operative in an EDS system and the dynamic stability of such systems.« less

Dynamic stability of maglev systems

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

Cai, Y.; Chen, S.S.; Mulcahy, T.M.

1994-05-01

Because dynamic instabilities are not acceptable in any commercial maglev system, it is important to consider dynamic instability in the development of all maglev systems. This study considers the stability of maglev systems based on experimental data, scoping calculations, and simple mathematical models. Divergence and flutter are obtained for coupled vibration of a three-degree-of-freedom maglev vehicle on a guideway consisting of double L-shaped aluminum segments. The theory and analysis developed in this study provides basic stability characteristics and identifies future research needs for maglev systems.

Early Dynamics and Stabilization Mechanisms of Oil-in-Water Emulsions Containing Colloidal Particles Modified with Short Amphiphiles: A Numerical Study.

PubMed

Cerbelaud, Manuella; Videcoq, Arnaud; Alison, Lauriane; Tervoort, Elena; Studart, André R

2017-12-19

Emulsions stabilized by mixtures of particles and amphiphilic molecules are relevant for a wide range of applications, but their dynamics and stabilization mechanisms on the colloidal level are poorly understood. Given the challenges to experimentally probe the early dynamics and mechanisms of droplet stabilization, Brownian dynamics simulations are developed here to study the behavior of oil-in-water emulsions stabilized by colloidal particles modified with short amphiphiles. Simulation parameters are based on an experimental system that consists of emulsions obtained with octane as the oil phase and a suspension of alumina colloidal particles modified with short carboxylic acids as the continuous aqueous medium. The numerical results show that attractive forces between the colloidal particles favor the formation of closely packed clusters on the droplet surface or of a percolating network of particles throughout the continuous phase, depending on the amphiphile concentration. Simulations also reveal the importance of a strong adsorption of particles at the liquid interface to prevent their depletion from the droplet surface when another droplet approaches. Strongly adsorbed particles remain immobile on the droplet surface, generating an effective steric barrier against droplet coalescence. These findings provide new insights into the early dynamics and mechanisms of stabilization of emulsions using particles and amphiphilic molecules.

Solar Dynamic Power System Stability Analysis and Control

NASA Technical Reports Server (NTRS)

Momoh, James A.; Wang, Yanchun

1996-01-01

The objective of this research is to conduct dynamic analysis, control design, and control performance test of solar power system. Solar power system consists of generation system and distribution network system. A bench mark system is used in this research, which includes a generator with excitation system and governor, an ac/dc converter, six DDCU's and forty-eight loads. A detailed model is used for modeling generator. Excitation system is represented by a third order model. DDCU is represented by a seventh order system. The load is modeled by the combination of constant power and constant impedance. Eigen-analysis and eigen-sensitivity analysis are used for system dynamic analysis. The effects of excitation system, governor, ac/dc converter control, and the type of load on system stability are discussed. In order to improve system transient stability, nonlinear ac/dc converter control is introduced. The direct linearization method is used for control design. The dynamic analysis results show that these controls affect system stability in different ways. The parameter coordination of controllers are recommended based on the dynamic analysis. It is concluded from the present studies that system stability is improved by the coordination of control parameters and the nonlinear ac/dc converter control stabilize system oscillation caused by the load change and system fault efficiently.

Percutaneous transluminal myocardial revascularisation: current status and future perspectives.

PubMed

Rath, P C; Agarwala, M K

2000-11-01

Percutaneous transluminal myocardial revascularisation presently appears to be a potential palliative treatment for coronary artery disease, neither controlled with drugs nor amenable to available coronary revascularisation techniques. Ongoing trials will provide answer to short and long term efficacy. Recent developments using angiogenic growth factors appear very promising, and the role of growth factors as an adjunct to percutaneous transmyocardial revascularisation with laser remains to be seen.

Percutaneous CT-Guided Biopsy of C3 Vertebral Body: Modified Approach for an Old Procedure

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

Pua, Uei, E-mail: druei@yahoo.com; Chan, Stephen Yung-Wei

2013-06-15

Percutaneous biopsy of upper cervical vertebrae is challenging due to the various critical structures in the location and often requires difficult trajectory such as transoral or paramaxillary approaches. The purpose of this manuscript is to illustrate the utility of head rotation in creating a potential space for direct percutaneous access to C3 vertebral body for safe biopsy.

Italian Percutaneous EVAR (IPER) Registry: outcomes of 2381 percutaneous femoral access sites' closure for aortic stent-graft.

PubMed

Pratesi, G; Barbante, M; Pulli, R; Fargion, A; Dorigo, W; Bisceglie, R; Ippoliti, A; Pratesi, C

2015-12-01

The aim of this paper was to report outcomes of endovascular aneurysm repair with percutaneous femoral access (pEVAR) using Prostar XL and Proglide closure systems (Abbot Vascular, Santa Clara, CA, USA), from the multicenter Italian Percutaneous EVAR (IPER) registry. Consecutive patients affected by aortic pathology treated by EVAR with percutaneous access (pEVAR) between January 2010 and December 2014 at seven Italian centers were enrolled in this multicenter registry. All the operators had an experience of at least 50 percutaneous femoral access procedures. Data were prospectively collected into a dedicated online database including patient's demographics, anatomical features, intra- and postoperative outcomes. A retrospective analysis was carried out to report intraoperative and 30-day technical success and access-related complication rate. Uni- and multivariate analyses were performed to identify factors potentially associated with an increased risk of percutaneous pEVAR failure. A total of 2381 accesses were collected in 1322 patients, 1249 (94.4%) male with a mean age of 73.5±8.3 years (range 45-97). The overall technical success rate was 96.8% (2305/2381). Major intraoperative access-related complications requiring conversion to surgical cut-down were observed in 3.2% of the cases (76/2381). One-month pEVAR failure-rate was 0.25% (6/2381). Presence of femoral artery calcifications resulted to be a significant predictor of technical failure (OR: 1.69; 95% CI: 1.03-2.77; P=0.036) at multivariate analysis. No significant association was observed with sex (P=0.28), obesity (P=0.64), CFA diameter (P=0.32), level of CFA bifurcation (P=0.94) and sheath size >18 F (P=0.24). The use of Proglide was associated with a lower failure rate compared to Prostar XL (2.5% vs. 3.3%) despite not statistically significant (P=0.33). The results of the IPER registry confirm the high technical success rate of percutaneous EVAR when performed by experienced operators, even in presence of demanding anatomies. Femoral calcification represents the only predictor of percutaneous access failure.

Surface effects on dynamic stability and loading during outdoor running using wireless trunk accelerometry.

PubMed

Schütte, Kurt H; Aeles, Jeroen; De Beéck, Tim Op; van der Zwaard, Babette C; Venter, Rachel; Vanwanseele, Benedicte

2016-07-01

Despite frequently declared benefits of using wireless accelerometers to assess running gait in real-world settings, available research is limited. The purpose of this study was to investigate outdoor surface effects on dynamic stability and dynamic loading during running using tri-axial trunk accelerometry. Twenty eight runners (11 highly-trained, 17 recreational) performed outdoor running on three outdoor training surfaces (concrete road, synthetic track and woodchip trail) at self-selected comfortable running speeds. Dynamic postural stability (tri-axial acceleration root mean square (RMS) ratio, step and stride regularity, sample entropy), dynamic loading (impact and breaking peak amplitudes and median frequencies), as well as spatio-temporal running gait measures (step frequency, stance time) were derived from trunk accelerations sampled at 1024Hz. Results from generalized estimating equations (GEE) analysis showed that compared to concrete road, woodchip trail had several significant effects on dynamic stability (higher AP ratio of acceleration RMS, lower ML inter-step and inter-stride regularity), on dynamic loading (downward shift in vertical and AP median frequency), and reduced step frequency (p<0.05). Surface effects were unaffected when both running level and running speed were added as potential confounders. Results suggest that woodchip trails disrupt aspects of dynamic stability and loading that are detectable using a single trunk accelerometer. These results provide further insight into how runners adapt their locomotor biomechanics on outdoor surfaces in situ. Copyright © 2016 Elsevier B.V. All rights reserved.

Linear feedback stabilization of a dispersively monitored qubit

NASA Astrophysics Data System (ADS)

Patti, Taylor Lee; Chantasri, Areeya; García-Pintos, Luis Pedro; Jordan, Andrew N.; Dressel, Justin

2017-08-01

The state of a continuously monitored qubit evolves stochastically, exhibiting competition between coherent Hamiltonian dynamics and diffusive partial collapse dynamics that follow the measurement record. We couple these distinct types of dynamics together by linearly feeding the collected record for dispersive energy measurements directly back into a coherent Rabi drive amplitude. Such feedback turns the competition cooperative and effectively stabilizes the qubit state near a target state. We derive the conditions for obtaining such dispersive state stabilization and verify the stabilization conditions numerically. We include common experimental nonidealities, such as energy decay, environmental dephasing, detector efficiency, and feedback delay, and show that the feedback delay has the most significant negative effect on the feedback protocol. Setting the measurement collapse time scale to be long compared to the feedback delay yields the best stabilization.

Angioplasty and stent placement - heart

MedlinePlus

PCI; Percutaneous coronary intervention; Balloon angioplasty; Coronary angioplasty; Coronary artery angioplasty; Percutaneous transluminal coronary angioplasty; Heart artery dilatation; Angina - stent placement; Acute coronary ...

Status on the Verification of Combustion Stability for the J-2X Engine Thrust Chamber Assembly

NASA Technical Reports Server (NTRS)

Casiano, Matthew; Hinerman, Tim; Kenny, R. Jeremy; Hulka, Jim; Barnett, Greg; Dodd, Fred; Martin, Tom

2013-01-01

Development is underway of the J -2X engine, a liquid oxygen/liquid hydrogen rocket engine for use on the Space Launch System. The Engine E10001 began hot fire testing in June 2011 and testing will continue with subsequent engines. The J -2X engine main combustion chamber contains both acoustic cavities and baffles. These stability aids are intended to dampen the acoustics in the main combustion chamber. Verification of the engine thrust chamber stability is determined primarily by examining experimental data using a dynamic stability rating technique; however, additional requirements were included to guard against any spontaneous instability or rough combustion. Startup and shutdown chug oscillations are also characterized for this engine. This paper details the stability requirements and verification including low and high frequency dynamics, a discussion on sensor selection and sensor port dynamics, and the process developed to assess combustion stability. A status on the stability results is also provided and discussed.

Use of a surgical helmet system to minimize splash injury during percutaneous renal surgery in high-risk patients.

PubMed

Eandi, Jonathan A; Nanigian, Dana K; Smith, William H; Low, Roger K

2008-12-01

The transmission risk to surgeons performing percutaneous renal surgery on patients who are infected with human immunodeficiency virus/acquired immunodeficiency syndrome, hepatitis B, or hepatitis C is unknown. A recent study found 55% of surgeons' masks contain evidence of blood splash contamination after percutaneous nephrolithotomy. While the risk of infectious disease transmission to the surgeon after mucocutaneous exposure is unknown, the incapacitating disease these pathogens cause can have a devastating and permanent effect on a surgeon's career. We describe our use of a surgical helmet system when performing percutaneous renal surgery on high-risk patients to minimize risk of splash injury and transmission of blood-borne pathogens.

Percutaneous evacuation for treatment of subdural hematoma and outcome in 28 patients.

PubMed

Mostofi, Keyvan; Marnet, Dominique

2011-01-01

Chronic subdural hematoma is a frequently encountered entity in neurosurgery in particular in elderly patients. There in a high variance in the treatment in literature. We report our experience of percutaneous evacuation of chronic subdural hematoma in 28 patients. From January 2007 to July 2009, 28 patients underwent percutaneous evacuation. 27 of the 28 patients (96.4%) became asymptomatic or improved clinically. Six weeks later, the scan showed the hematoma had completely disappeared in 18 of the cases. We did not have any postoperative infection. Treatment of chronic subdural hematoma using a percutaneous operative technique is a minimally invasive method with sufficient outcome and a therapeutic alternative to the craniotomy.

Charles Theodore Dotter: The Father of Intervention

PubMed Central

Payne, Misty M.

2001-01-01

The 1st percutaneous transluminal angioplasty marked a new era in the treatment of peripheral atherosclerotic lesions. The early techniques used in peripheral percutaneous transluminal angioplasty form the basis for subsequent percutaneous intervention both in the peripheral and coronary arteries and are largely the contribution of Charles Dotter. Dotter was the 1st to describe flow-directed balloon catheterization, the double-lumen balloon catheter, the safety guidewire, percutaneous arterial stenting, and more. This practical genius dedicated his considerable energy to the belief that there is always a better way to treat disease. His personal contributions to clinical medicine, research, and teaching have saved millions of limbs and lives all over the world. PMID:11330737

Image-Guided Transvesicular Drainage of Pelvic Fluid Collections: A Safe and Effective Alternative Approach.

PubMed

Ayyagari, Raj R; Yeh, Cliff; Arici, Melih; Mojibian, Hamid; Reiner, Eric; Pollak, Jeffrey S

2016-05-01

To evaluate the safety and efficacy of percutaneous transvesicular drainage of pathologic pelvic fluid collections, a series of 15 patients who underwent 16 transvesicular drainage catheter placements was retrospectively reviewed. All patients had collections suspicious for infection that were posterior to the bladder or superior to the bladder behind loops of bowel, and were otherwise inaccessible. All 15 collections were percutaneously accessed via the bladder with standard drainage catheters. All collections resolved completely with no complications. Percutaneous transvesicular drainage was a safe and effective technique in this series, and can be considered when no direct percutaneous access routes are available. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

Splenic Injury During Percutaneous Nephrolithotomy

PubMed Central

Thomas, Anil A.; Pierce, Gregory; Walsh, R. Matthew; Sands, Mark

2009-01-01

Background: Injury to the spleen is a recognized complication during percutaneous renal access due to the close anatomical relationship of the spleen and the left kidney. However, transsplenic renal access is a rare complication of percutaneous nephrolithotomy and can also result in considerable morbidity, often requiring emergent splenectomy. Methods: We present our experience with splenic injury during percutaneous nephrolithotomy managed conservatively with the use of a collagen-thrombin hemostatic sealant (D-Stat; Vascular Solutions, Inc., Minneapolis, MN) after delayed removal of the nephrostomy tubes. Results: The patient had an uneventful recovery and was discharged home on postoperative day 6. Conclusion: In select hemodynamically stable patients, nonoperative management with the adjunctive use of hemostatic sealants may be considered. PMID:19660224

[Nonsurgical therapy of abdominal and retroperitoneal abscesses].

PubMed

Reuss, J A; Seitz, K

1987-06-01

From 1976 to March 1987 intraabdominal or retroperitoneal abscesses were confirmed by ultrasound in 40 patients. 13 patients had surgical drainage with zero-mortality. 3 of 27 patients were treated with antibiotics (only systemically). 24 patients were treated by percutaneous catheter drainage or needle aspiration. Elective cholecystectomy was performed later in 3 patients. Nonsurgical treatment was successful in 22/27 cases. 3 patients died despite percutaneous drainage. Failure of percutaneous drainage required surgical intervention in 3 patients. The considerably poorer primary condition of the patients receiving nonsurgical treatment allows no comparison with the surgical group. Advantages of percutaneous drainage and needle aspiration are a high success rate and low mortality. These techniques can be used even in critically ill persons.

Safe and effective treatment of early suprahepatic inferior vena caval outflow compromise following orthotopic liver transplantation using percutaneous transluminal angioplasty and stent placement.

PubMed

Tasse, Jordan; Borge, Marc; Pierce, Kenneth; Brems, John

2011-01-01

To describe the safety and efficacy of percutaneous transluminal angioplasty and stent placement in patients presenting with suprahepatic inferior vena cava (IVC) outflow compromise in the early postoperative period following orthotopic liver transplantation. Between October 2002 and April 2009, 3 patients presented with IVC outflow compromise in the first 2 months following orthotopic liver transplantation. All 3 underwent percutaneous transluminal angioplasty and stent placement without complication and showed significant clinical improvement at short and intermediate term follow-up. Percutaneous transluminal angioplasty and Gianturco stent placement is a safe and effective treatment for IVC outflow compromise in the early postoperative period following orthotopic liver transplantation.

Individuals with chronic ankle instability exhibit dynamic postural stability deficits and altered unilateral landing biomechanics: A systematic review.

PubMed

Simpson, Jeffrey D; Stewart, Ethan M; Macias, David M; Chander, Harish; Knight, Adam C

2018-06-13

To evaluate the literature regarding unilateral landing biomechanics and dynamic postural stability in individuals with and without chronic ankle instability (CAI). Four online databases (PubMed, ScienceDirect, Scopus, and SportDiscus) were searched from the earliest records to 31 January 2018, as well as reference sections of related journal articles, to complete the systematic search. Studies investigating the influence of CAI on unilateral landing biomechanics and dynamic postural stability were systematically reviewed and evaluated. Twenty articles met the criteria and were included in the systematic review. Individuals with CAI were found to have deficits in dynamic postural stability on the affected limb with medium to large effect sizes and altered lower extremity kinematics, most notably in the ankle and knee, with medium to large effect sizes. Additionally, greater loading rates and peak ground reaction forces, in addition to reductions in ankle muscle activity were also found in individuals with CAI during unilateral jump-landing tasks. Individuals with CAI demonstrate dynamic postural stability deficits, lower extremity kinematic alterations, and reduced neuromuscular control during unilateral jump-landings. These are likely factors that contribute recurrent lateral ankle sprain injuries during dynamic activity in individuals with CAI. Copyright © 2018 Elsevier Ltd. All rights reserved.

Recent Advances in Heliogyro Solar Sail Structural Dynamics, Stability, and Control Research

NASA Technical Reports Server (NTRS)

Wilkie, W. Keats; Warren, Jerry E.; Horta, Lucas G.; Lyle, Karen H.; Juang, Jer-Nan; Gibbs, S. Chad; Dowell, Earl H.; Guerrant, Daniel V.; Lawrence, Dale

2015-01-01

Results from recent NASA sponsored research on the structural dynamics, stability, and control characteristics of heliogyro solar sails are summarized. Specific areas under investigation include coupled nonlinear finite element analysis of heliogyro membrane blade with solar radiation pressure effects, system identification of spinning membrane structures, and solarelastic stability analysis of heliogyro solar sails, including stability during blade deployment. Recent results from terrestrial 1-g blade dynamics and control experiments on "rope ladder" membrane blade analogs, and small-scale in vacuo system identification experiments with hanging and spinning high-aspect ratio membranes will also be presented. A low-cost, rideshare payload heliogyro technology demonstration mission concept is used as a mission context for these heliogyro structural dynamics and solarelasticity investigations, and is also described. Blade torsional dynamic response and control are also shown to be significantly improved through the use of edge stiffening structural features or inclusion of modest tip masses to increase centrifugal stiffening of the blade structure. An output-only system identification procedure suitable for on-orbit blade dynamics investigations is also developed and validated using ground tests of spinning sub-scale heliogyro blade models. Overall, analytical and experimental investigations to date indicate no intractable stability or control issues for the heliogyro solar sail concept.

Computational Methods for Dynamic Stability and Control Derivatives

NASA Technical Reports Server (NTRS)

Green, Lawrence L.; Spence, Angela M.; Murphy, Patrick C.

2003-01-01

Force and moment measurements from an F-16XL during forced pitch oscillation tests result in dynamic stability derivatives, which are measured in combinations. Initial computational simulations of the motions and combined derivatives are attempted via a low-order, time-dependent panel method computational fluid dynamics code. The code dynamics are shown to be highly questionable for this application and the chosen configuration. However, three methods to computationally separate such combined dynamic stability derivatives are proposed. One of the separation techniques is demonstrated on the measured forced pitch oscillation data. Extensions of the separation techniques to yawing and rolling motions are discussed. In addition, the possibility of considering the angles of attack and sideslip state vector elements as distributed quantities, rather than point quantities, is introduced.

Computational Methods for Dynamic Stability and Control Derivatives

NASA Technical Reports Server (NTRS)

Green, Lawrence L.; Spence, Angela M.; Murphy, Patrick C.

2004-01-01

Force and moment measurements from an F-16XL during forced pitch oscillation tests result in dynamic stability derivatives, which are measured in combinations. Initial computational simulations of the motions and combined derivatives are attempted via a low-order, time-dependent panel method computational fluid dynamics code. The code dynamics are shown to be highly questionable for this application and the chosen configuration. However, three methods to computationally separate such combined dynamic stability derivatives are proposed. One of the separation techniques is demonstrated on the measured forced pitch oscillation data. Extensions of the separation techniques to yawing and rolling motions are discussed. In addition, the possibility of considering the angles of attack and sideslip state vector elements as distributed quantities, rather than point quantities, is introduced.

Advance Ratio Effects on the Dynamic-stall Vortex of a Rotating Blade in Steady Forward Flight

DTIC Science & Technology

2014-08-06

dependence on advance ratio is used to relate the stability of the dynamic-stall vortex to Coriolis effects . Advance ratio effects on the dynamic-stall vortex...relate the stability of the dynamic-stall vortex to Coriolis effects . Keywords: Leading-edge vortex, Dynamic stall vortex, Vortex flows, Rotating wing...Reynolds number are not decoupled. 3. Radial flow field In the rotating environment the coupled effect of centripetal and Coriolis accelerations is ex

Indication and short-term clinical outcomes of high-risk percutaneous coronary intervention with microaxial Impella® pump: results from the German Impella® registry.

PubMed

Baumann, Stefan; Werner, Nikos; Ibrahim, Karim; Westenfeld, Ralf; Al-Rashid, Fadi; Sinning, Jan-Malte; Westermann, Dirk; Schäfer, Andreas; Karatolios, Konstantinos; Bauer, Timm; Becher, Tobias; Akin, Ibrahim

2018-03-08

Percutaneous coronary intervention (PCI) is an alternative strategy to coronary artery bypass grafting (CABG) in patients with high perioperative risk. The microaxial Impella ® pump (Abiomed, Danvers, MA, USA), used as prophylactic and temporary support, is currently the most common device for "protected high-risk PCI" to ensure hemodynamic stability during complex coronary intervention. The study is an observational, retrospective multi-center registry. Patients from nine tertiary hospitals in Germany, who have undergone protected high-risk PCI, are included in the present study. A total of 154 patients (mean age 72.6-10.8 years, 75.3% male) were enrolled. The majority were at a high operative risk illustrated by a logistic EuroSCORE of 14.7-17.4. The initial SYNTAX score was 32.0-13.3, indicating very complex CAD and could be reduced to 14.1-14.3 (p < 0.0001) after PCI. The main reasons for protected PCI were complex coronary anatomy (70.8%), personal impression (56.5%), reduced ventricular ejection fraction (49.4%), comorbidities (47.4%), and surgical turndown (30.5%). Four patients (2.6%) experienced an intrahospital death. Data from the study show that protected PCI is a safe and effective approach to revascularize high-risk patients with complex coronary anatomy and comorbidities.

3-Dimensional printing guide template assisted percutaneous vertebroplasty: Technical note.

PubMed

Li, Jian; Lin, JiSheng; Yang, Yong; Xu, JunChuan; Fei, Qi

2018-06-01

Percutaneous vertebroplasty (PVP) is currently considered as an effective treatment for pain caused by acute osteoporotic vertebral compression fracture. Recently, puncture-related complications are increasingly reported. It's important to find a precise technique to reduce the puncture-related complications. We report a case and discussed the novel surgical technique with step-by-step operating procedures, to introduce the precise PVP assisted by a 3-dimensional printing guide template. Based on the preoperative CT scan and infrared scan data, a well-designed individual guide template could be established in a 3-dimensional reconstruction software and printed out by a 3-dimensional printer. In real operation, by matching the guide template to patient's back skin, cement needles' insertion orientation and depth were easily established. Only 14 times C-arm fluoroscopy with HDF mode (total exposure dose was 4.5 mSv) were required during the procedure. The operation took only 17 min. Cement distribution in the vertebral body was very good without any puncture-related complications. Pain was significantly relieved after surgery. In conclusion, the novel precise 3-dimensional printing guide template system may allow (1) comprehensive visualization of the fractured vertebral body and the individual surgical planning, (2) the perfect fitting between skin and guide template to ensure the puncture stability and accuracy, and (3) increased puncture precision and decreased puncture-related complications, surgical time and radiation exposure. Copyright © 2018 Elsevier Ltd. All rights reserved.

Stereotypy and Motor Control: Differences in the Postural Stability Dynamics of Persons with Stereotyped and Dyskinetic Movement Disorders.

ERIC Educational Resources Information Center

Bodfish, James W.; Parker, Dawn E.; Lewis, Mark H.; Sprague, Robert L.; Newell, Karl M.

2001-01-01

This study examined whether dynamic measures of postural stability differentiated stereotyped movement disorder from dyskinetic movement disorder in a severely mentally retarded population. Participants (N=20) with either stereotypy or dyskinesia movement disorders and a control group were given a goal-oriented postural stability task. Both groups…

Dynamic Stability of Maglev Systems,

DTIC Science & Technology

1992-04-01

AD-A259 178 ANL-92/21 Materials and Components Dynamic Stability of Technology Division Materials and Components Maglev Systems Technology Division...of Maglev Systems Y. Cai, S. S. Chen, and T. M. Mulcahy Materials and Components Technology Division D. M. Rote Center for Transportation Research...of Maglev System with L-Shaped Guideway ......................................... 6 3 Stability of M aglev System s

Large-scale systems: Complexity, stability, reliability

NASA Technical Reports Server (NTRS)

Siljak, D. D.

1975-01-01

After showing that a complex dynamic system with a competitive structure has highly reliable stability, a class of noncompetitive dynamic systems for which competitive models can be constructed is defined. It is shown that such a construction is possible in the context of the hierarchic stability analysis. The scheme is based on the comparison principle and vector Liapunov functions.

Kirschner wire pin tract infection rates between percutaneous and buried wires in treating metacarpal and phalangeal fractures.

PubMed

Rafique, Atif; Ghani, Shahab; Sadiq, Moiz; Siddiqui, Intisar Ahmed

2006-08-01

To compare pin tract infection rate between percutaneous and buried placement of Kirschner (K-) wiring for hand fractures. Quasi--experimental study. Plastic, Reconstructive, Hand and Burn Surgery Unit, Liaquat National Hospital, Karachi, from September 2005--February 2006. Patients with fractures of metacarpals and phalanges of hand were selected by non-probability purposive method. Assessment of pin tract infection by clinical examination and pin tract scoring was done by modification of Oppenheim classification. Statistical analysis was done using Chi-square test. Ten out of 55 percutaneous and 2 out of 45 buried wires were infected. The difference in infection rates of two groups was statistically significant at p<0.05. Three percutaneous, but not buried Kirschner wires, had to be removed before 4 weeks because of failure to respond to local wound care and oral antibiotics. Percutaneous K- wires had significantly greater infection rate than wires which were buried deep to the skin.

Percutaneous management of coronary sinus atrial septal defect: two cases representing the spectrum for device closure and a review of the literature.

PubMed

Sandeep, Nefthi; Slack, Michael C

2014-10-01

Coronary sinus atrial septal defects are the rarest defects of the atrial septum comprising <1% of the five different types of atrial septal defects. Despite the widespread adoption of percutaneous device closure of secundum atrial septal defects, the published experience with percutaneous device closure of coronary sinus atrial septal defects is limited to only a few isolated case reports because of uncertainty regarding safety and efficacy. Open-heart surgical repair remains the treatment of choice for coronary sinus atrial septal defects, although this may not be the only treatment option in selected cases. Herein we describe our own experience with two patients with different clinical presentations and our method of successful percutaneous coronary sinus atrial septal defect closure in each. We then present a review of the anatomic spectrum of coronary sinus atrial septal defects along with a review of contemporary surgical and percutaneous device treatment.

Percutaneous Dual-valve Intervention in a High-risk Patient with Severe Aortic and Mitral Stenosis

PubMed Central

Mrevlje, Blaz; Aboukura, Mohamad; Nienaber, Christoph A.

2016-01-01

Aortic stenosis is the most frequent and mitral stenosis is the least frequent native single-sided valve disease in Europe. Patients with the combination of severe symptomatic degenerative aortic and mitral stenosis are very rare. Guidelines for the treatment of heart valve diseases are clear for single-valve situations. However, there is no common agreement or recommendation for the best treatment strategy in patients with multiple valve disease and severe concomitant comorbidities. A 76-year-old female patient with the combination of severe degenerative symptomatic aortic and mitral stenosis and several comorbidities including severe obesity, who was found unsuitable surgical candidate by the heart team and unsuitable for two-time general anesthesia in the case of two-step single-valve percutaneous approach by anesthesiologists, underwent successful percutaneous dual-valve single-intervention (transcatheter aortic valve implantation and percutaneous mitral balloon commissurotomy). Percutaneous dual-valve single-intervention is feasible in selected symptomatic high-risk patients. PMID:27867460

Orthogonal Operation of Constitutional Dynamic Networks Consisting of DNA-Tweezer Machines.

PubMed

Yue, Liang; Wang, Shan; Cecconello, Alessandro; Lehn, Jean-Marie; Willner, Itamar

2017-12-26

Overexpression or down-regulation of cellular processes are often controlled by dynamic chemical networks. Bioinspired by nature, we introduce constitutional dynamic networks (CDNs) as systems that emulate the principle of the nature processes. The CDNs comprise dynamically interconvertible equilibrated constituents that respond to external triggers by adapting the composition of the dynamic mixture to the energetic stabilization of the constituents. We introduce a nucleic acid-based CDN that includes four interconvertible and mechanically triggered tweezers, AA', BB', AB' and BA', existing in closed, closed, open, and open configurations, respectively. By subjecting the CDN to auxiliary triggers, the guided stabilization of one of the network constituents dictates the dynamic reconfiguration of the structures of the tweezers constituents. The orthogonal and reversible operations of the CDN DNA tweezers are demonstrated, using T-A·T triplex or K + -stabilized G-quadruplex as structural motifs that control the stabilities of the constituents. The implications of the study rest on the possible applications of input-guided CDN assemblies for sensing, logic gate operations, and programmed activation of molecular machines.

Functional assessment of coronary artery disease by intravascular ultrasound and computational fluid dynamics simulation.

PubMed

Carrizo, Sebastián; Xie, Xinzhou; Peinado-Peinado, Rafael; Sánchez-Recalde, Angel; Jiménez-Valero, Santiago; Galeote-Garcia, Guillermo; Moreno, Raúl

2014-10-01

Clinical trials have shown that functional assessment of coronary stenosis by fractional flow reserve (FFR) improves clinical outcomes. Intravascular ultrasound (IVUS) complements conventional angiography, and is a powerful tool to assess atherosclerotic plaques and to guide percutaneous coronary intervention (PCI). Computational fluid dynamics (CFD) simulation represents a novel method for the functional assessment of coronary flow. A CFD simulation can be calculated from the data normally acquired by IVUS images. A case of coronary heart disease studied with FFR and IVUS, before and after PCI, is presented. A three-dimensional model was constructed based on IVUS images, to which CFD was applied. A discussion of the literature concerning the clinical utility of CFD simulation is provided. Copyright © 2014 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

Ultrasound-Guided Percutaneous Electrolysis and Eccentric Exercises for Subacromial Pain Syndrome: A Randomized Clinical Trial

PubMed Central

Arias-Buría, José L.; Truyols-Domínguez, Sebastián; Valero-Alcaide, Raquel; Salom-Moreno, Jaime; Atín-Arratibel, María A.; Fernández-de-las-Peñas, César

2015-01-01

Objective. To compare effects of ultrasound- (US-) guided percutaneous electrolysis combined with an eccentric exercise program of the rotator cuff muscles in subacromial pain syndrome. Methods. Thirty-six patients were randomized and assigned into US-guided percutaneous electrolysis (n = 17) group or exercise (n = 19) group. Patients were asked to perform an eccentric exercise program of the rotator cuff muscles twice every day for 4 weeks. Participants assigned to US-guided percutaneous electrolysis group also received the application of galvanic current through acupuncture needle on each session once a week (total 4 sessions). Shoulder pain (NPRS) and disability (DASH) were assessed at baseline, after 2 sessions, and 1 week after the last session. Results. The ANOVA revealed significant Group∗Time interactions for shoulder pain and disability (all, P < 0.01): individuals receiving US-guided percutaneous electrolysis combined with the eccentric exercises experienced greater improvement than those receiving eccentric exercise alone. Conclusions. US-guided percutaneous electrolysis combined with eccentric exercises resulted in small better outcomes at short term compared to when only eccentric exercises were applied in subacromial pain syndrome. The effect was statistically and clinically significant for shoulder pain but below minimal clinical difference for function. Future studies should investigate the long-term effects and potential placebo effect of this intervention. PMID:26649058

Laparoscopic ureterolysis with simultaneous ureteroscopy and percutaneous nephroscopy for treating complex ureteral obstruction after failed endoscopic intervention: A technical report.

PubMed

Wang, Zhixiang; Liu, Bing; Gao, Xiaofeng; Bao, Yi; Wang, Yang; Ye, Huamao; Sun, Yinghao; Wang, Linhui

2015-10-01

Complex ureteral obstruction is refractory to conventional urological intervention. This report describes a case of laparoscopic ureterolysis with simultaneous ureteroscopy and percutaneous nephroscopy for treating complex ureteral obstruction. Right-side multiple ureteral stones and complicating ureteral obstruction failed an initial attempt of ureteroscopy lithotripsy with simultaneous percutaneous nephroscopy in a 23-year-old male. Laparoscopic ureterolysis with ureteroscopy and percutaneous nephroscopy was used simultaneously to dissect the periureteral adhesions with the patient placed in the Galdakao-modified supine Valdivia position. The ureter was incised to allow the insertion of a ureteral catheter through the twisted ureter, and a guide wire was advanced into the pelvis using ureteroscopy. A double-J stent was placed into the right-side ureter using antegrade percutaneous nephroscopy. The laparoendoscopic procedure lasted 330 min with an estimated bleeding volume of 100 mL. The patient underwent an uneventful postoperative course, and postoperative follow-up radiography confirmed good positioning of the double-J stent. The double-J stent was removed 3 months after operation. The patient remained asymptomatic within a 13-month follow-up period. Laparoscopic ureterolysis with simultaneous ureteroscopy and percutaneous nephroscopy is an effective and safe treatment option for complex ureteral obstruction.

Percutaneous Microwave Ablation in the Spleen for Treatment of Hypersplenism in Cirrhosis Patients.

PubMed

Jiang, XiangWu; Gao, Fei; Ma, Yan; Feng, ShuFen; Liu, XueLian; Zhou, HongKe

2016-01-01

The aim of this study was to estimate the feasibility and therapeutic effectiveness of percutaneous microwave ablation in the treatment of hypersplenism in cirrhosis. Forty-one cirrhosis patients with hypersplenism were treated with ultrasonography-guided percutaneous microwave ablation between February 2007 and August 2011. Peripheral blood cell counts, portal vein diameter, splenic vein diameter, and blood flow of splenic vein were evaluated before and after the operation, and complications of the treatment were also investigated. All patients were followed up for 24 months. The levels of platelets and white blood cells were increased, while the splenic vein diameter narrowed gradually after the therapy and 24 months later. Moreover, patients received percutaneous microwave ablation had much lower splenic venous flow velocity. The portal vein diameter did not change significantly 6 months after the treatment, although it narrowed gradually within 3 months after the treatment. Furthermore, no complications such as uncontrollable bleeding, splenic abscess, spleen rupture, and damage in surrounding organ happened after the therapy. Graded percutaneous microwave ablation, as a minimally invasive therapy, could damage the spleen, increase the levels of platelets and white blood cells, and reduce portal hypertension effectively without serious complications. Percutaneous microwave ablation is an effective, safe, and feasible method for cirrhosis patients with hypersplenism.

The CROES percutaneous nephrolithotomy global study: the influence of body mass index on outcome.

PubMed

Fuller, Andrew; Razvi, Hassan; Denstedt, John D; Nott, Linda; Pearle, Margaret; Cauda, Furio; Bolton, Damien; Celia, Antonio; de la Rosette, Jean

2012-07-01

In addition to more commonly forming stones, obese patients present a number of challenges when undergoing percutaneous nephrolithotomy. We evaluated percutaneous nephrolithotomy outcomes in 3,709 patients stratified by body mass index. A prospective database administered by CROES (Clinical Research Office of the Endourological Society) captured data on 5,803 patients treated with percutaneous nephrolithotomy between November 2007 and December 2009. Patients with known solitary kidney, previous percutaneous nephrolithotomy and congenital abnormalities were excluded from analysis. For statistical analysis patients were categorized as normal weight--body mass index 18.5 to 25 kg/m(2), overweight--25 to 30, obese--30 to 40 and super obese--greater than 40. During the study period 5,803 patients underwent percutaneous nephrolithotomy, of whom 3,709 met the inclusion criteria. As expected, obesity was associated with significantly higher rates of comorbid conditions and anticoagulant use (p < 0.001). Operative time was significantly longer in obese patients and use of a balloon device for tract dilation was more common (each p < 0.001). The stone-free rate decreased with obesity (p = 0.009), corresponding to a significantly higher re-treatment rate in this group (p < 0.001). No difference was seen in length of stay or the transfusion rate. No significant difference was seen in the overall complication rate among the 4 groups (p = 0.707). Percutaneous nephrolithotomy may be done safely in obese patients, although with a longer operative time, an inferior stone-free rate and a higher re-intervention rate. Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Transcatheter Arterial Embolization for Hepatic Arterial Injury Related to Percutaneous Transhepatic Portal Intervention

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

Shimohira, Masashi, E-mail: mshimohira@gmail.com; Hashizume, Takuya; Sasaki, Shigeru

PurposeTo assess the usefulness of transcatheter arterial embolization (TAE) for the hepatic arterial injury related to percutaneous transhepatic portal intervention (PTPI).Materials and MethodsFifty-four patients, 32 males and 22 females with a median age of 68 years (range 43–82 years), underwent PTPI. The procedures consisted of 33 percutaneous transhepatic portal vein embolizations, 19 percutaneous transhepatic variceal embolizations, and 2 percutaneous transhepatic portal venous stent placements. Two patients with gastric varices underwent percutaneous transhepatic variceal embolization twice because of recurrence. Therefore, the total number of procedures was 56. Among them, hepatic arterial injury occurred in 6 PTPIs in 5 patients, and TAE was performed.more » We assessed technical success, complications related to TAE, and clinical outcome. Technical success was defined as the disappearance of findings due to hepatic arterial injury on digital subtraction angiography.ResultsAs hepatic arterial injuries, 4 extravasations and 2 arterioportal shunts developed. All TAEs were performed successfully. The technical success rate was 100 %. Complication of TAE occurred in 5 of 6 TAEs; 3 were focal liver infarction, not requiring further treatment, and 2 were biloma that required percutaneous drainage. Five TAEs in 4 patients were performed immediately after the PTPI, and these 4 patients were alive. However, one TAE was performed 10 h later, and the patient died due to multiple organ failure 2 months later although TAE was successful.ConclusionTAE is a useful treatment for hepatic arterial injury related to PTPI. However, it should be performed at an early stage.« less

Treatment of Intra-abdominal Abscesses in Crohn’s Disease – A Nationwide Analysis of Patterns and Outcomes of Care

PubMed Central

Ananthakrishnan, Ashwin N; McGinley, Emily L

2013-01-01

Background Abdominal abscesses are a common complication in Crohn’s disease (CD). Percutaneous drainage of such abscesses has become increasingly popular and may deliver outcomes comparable to surgical treatment; however, such comparative data are limited from single center studies. There have been no nationally representative studies comparing different treatment modalities for abdominal abscesses. Methods We identified all adult CD-related non-elective hospitalizations from the Nationwide Inpatient Sample 2007 that were complicated by an intra-abdominal abscess. Treatment modality was categorized into 3 strata – medical treatment alone, percutaneous drainage, and surgery. We analyzed the nationwide patterns in the treatment and outcomes of each treatment modality and examined for patient demographic, disease, or hospital-related disparities in treatment and outcome. Results There were an estimated 3,296 hospitalizations for abdominal abscesses in patients with CD. Approximately 39% were treated by medical treatment alone, 29% with percutaneous drainage, and 32% with surgery with a significant increase in the use of percutaneous drainage since 1998 (7%). Co-morbidity burden, admission to a teaching hospital, and complicated Crohn’s disease (fistulae, stricture) were associated with non-medical treatment. Use of percutaneous drainage was more common in teaching hospitals. Mean time to percutaneous drainage and surgical treatment were 4.6 and 3.3 days respectively and early intervention was associated with significantly shorter hospitalization. Conclusions We describe the nationwide pattern in the treatment of abdominal abscesses and demonstrate an increase in the use of percutaneous drainage for the treatment of this subgroup. Early treatment intervention was predictive of shorter hospitalization. PMID:23392744

Results of percutaneous sclerotherapy and surgical treatment in patients with symptomatic simple liver cysts and polycystic liver disease

PubMed Central

Erdogan, Deha; van Delden, Otto M; Rauws, Erik AJ; Busch, Olivier RC; Lameris, Johan S; Gouma, Dirk J; van Gulik, Thomas M

2007-01-01

AIM: To evaluate the results of the treatment of simple liver cysts (solitary and multiple) and polycystic liver disease (PLD) using percutaneous sclerotherapy and/or surgical procedures in a single tertiary referral centre. METHODS: Retrospective analysis of 54 patients referred for evaluation and possible treatment of simple liver cysts (solitary and multiple) and PLD, from January 1997 to July 2006. RESULTS: Simple liver cysts were treated in 41 pts (76%) with a mean size of 12.6 cm. The most common reason for referral was abdominal pain or discomfort (85%). Percutaneous sclerotherapy was performed as initial treatment in 30 pts, showing cyst recurrence in 6 pts (20%). Surgical treatment was initially performed in 11 pts with cyst recurrence in 3 pts (27%). PLD was treated in 13 pts (24%) with a mean size of the dominant cyst of 13 cm. Percutaneous sclerotherapy for PLD was performed in 9 pts with recurrence in 7 pts (77.8%). Surgical treatment for PLD was undertaken in 4 pts (30.8%) with recurrence in all. Eventually, 2 pts with PLD in the presence of polycystic kidney disease underwent liver- and kidney transplantation because of deterioration of liver and kidney function. CONCLUSION: The majority of patients with simple liver cysts and PLD are referred for progressive abdominal pain. As initial treatment, percutaneous sclerotherapy is appropriate. Surgical deroofing is indicated in case of cyst recurrence after percutaneous sclerotherapy. However, the results of percutaneous sclerotherapy and surgical treatment for PLD are disappointing. Partial liver resection is indicated when there is suspicion of a pre-malignant lesion. PMID:17589926

Cryotherapy of the nephrostomy tract: a novel technique to decrease the risk of hemorrhage after tubeless percutaneous renal surgery.

PubMed

Okeke, Zeph; Andonian, Sero; Srinivasan, Arun; Shapiro, Edan; Vanderbrink, Brian A; Kavoussi, Louis R; Smith, Arthur D

2009-03-01

Delayed hemorrhage and significant postoperative pain are associated with complex percutaneous renal surgery. Cryoablation of the percutaneous nephrostomy tract after endoscopic procedures is a potential means of preventing delayed renal hemorrhage. In this study, we investigated the efficacy of this technique by comparing a group of patients who underwent this approach with another group who had nephrostomy tube insertion after percutaneous renal surgery. Sixty patients with complex renal calculi or ureteropelvic junction (UPJ) obstruction underwent percutaneous endoscopic management of their disease. At the conclusion of the procedure, 30 consecutive patients underwent a single 10-minute freeze-thaw cycle, in which a cryoprobe traversed the nephrostomy tract. These 30 patients were compared with the preceding 30 patients who had a nephrostomy tube inserted after complex percutaneous renal surgery. The two groups were well matched in terms of age, body mass index, total stone burden, number of patients with full staghorn calculi, and number of patients with concomitant UPJ obstruction. The cryotherapy group had a significantly shorter hospital stay (2.1 v 3.6 days, P < 0.001); decreased rates of delayed bleeding episodes (3% v 13%, P < 0.001), and urinary leak (0% v 10%, P < 0.001). Cryotherapy of the nephrostomy is a novel means of decreasing the risk of delayed postoperative hemorrhage after complex percutaneous renal surgery. It is associated with significantly decreased length of hospitalization postoperatively, as well as decreased risk of urine leakage compared with nephrostomy tubes in these groups of patients.

Percutaneous Implants with Porous Titanium Dermal Barriers: An In Vivo Evaluation of Infection Risk

PubMed Central

Isackson, Dorthyann; McGill, Lawrence D.; Bachus, Kent N.

2010-01-01

Osseointegrated percutaneous implants are a promising prosthetic alternative for a subset of amputees. However, as with all percutaneous implants, they have an increased risk of infection since they breach the skin barrier. Theoretically, host tissues could attach to the metal implant creating a barrier to infection. When compared with smooth surfaces, it is hypothesized that porous surfaces improve the attachment of the host tissues to the implant, and decrease the infection risk. In this study, 4 titanium implants, manufactured with a percutaneous post and a subcutaneous disk, were placed subcutaneously on the dorsum of eight New Zealand White rabbits. Beginning at four weeks post-op, the implants were inoculated weekly with 108 CFU Staphylococcus aureus until signs of clinical infection presented. While we were unable to detect a difference in the incidence of infection of the porous metal implants, smooth surface (no porous coating) percutaneous and subcutaneous components had a 7-fold increased risk of infection compared to the implants with a porous coating on one or both components. The porous coated implants displayed excellent tissue ingrowth into the porous structures; whereas, the smooth implants were surrounded with a thick, organized fibrotic capsule that was separated from the implant surface. This study suggests that porous coated metal percutaneous implants are at a significantly lower risk of infection when compared to smooth metal implants. The smooth surface percutaneous implants were inadequate in allowing a long-term seal to develop with the soft tissue, thus increasing vulnerability to the migration of infecting microorganisms. PMID:21145778

Comparison of intradermal and percutaneous testing to histamine, saline and nine allergens in healthy adult cats.

PubMed

Gentry, Christina M; Messinger, Linda

2016-10-01

Intradermal testing (IDT) in cats has potential limitations; this has led to an interest in novel testing methods. A pilot study demonstrated that healthy cats produced reliable percutaneous glycerinated (PG) histamine wheals, whereas percutaneously applied glycerosaline did not lead to wheal formation. The purpose of this study was to determine if percutaneously applied aqueous and glycerinated allergens would lead to irritant reactions in healthy cats. Percutaneous testing (PCT) with both glycerinated and aqueous allergens and IDT were compared in twelve healthy cats. The lateral thorax was clipped and histamine, saline and nine allergens were tested in rows. Objective and subjective evaluations were performed at 15, 20 and 25 min, and 4 h. Results were evaluated as positive or negative at 15, 20, 25 min and 4 h. Skin test reactions for intradermal (ID) histamine wheals were larger when compared to PG and percutaneous aqueous (PA) at the immediate reading points (P < 0.05) subjectively and objectively; however, PG was not significantly different from ID when compared as either positive (2-4) or negative (0-1). PG histamine and allergen reactions, when present, were larger than equivalent PA reactions. PG and PA allergens did not cause irritant reactions at tested concentrations. Bassia scoparia (kochia), when tested at 1000 PNU/mL with IDT, was suspected to be an irritant. Percutaneously (PCT) applied allergens did not cause irritant reactions in healthy cats. PG histamine wheals, although smaller than ID histamine wheals, were easily recognizable and PCT was simple to perform. © 2016 ESVD and ACVD.

Protein stability and dynamics influenced by ligands in extremophilic complexes - a molecular dynamics investigation.

PubMed

Khan, Sara; Farooq, Umar; Kurnikova, Maria

2017-08-22

In this study, we explore the structural and dynamic adaptations of the Tryptophan synthase α-subunit in a ligand bound state in psychrophilic, mesophilic and hyperthermophilic organisms at different temperatures by MD simulations. We quantify the global and local fluctuations in the 40 ns time scale by analyzing the root mean square deviation/fluctuations. The distinct behavior of the active site and loop 6 is observed with the elevation of temperature. Protein stability relies more on electrostatic interactions, and these interactions might be responsible for the stability of varying temperature evolved proteins. The paper also focuses on the effect of temperature on protein dynamics and stability governed by the distinct behavior of the ligand associated with its retention, binding and dissociation over the course of time. The integration of principle component analysis and a free energy landscape was useful in identifying the conformational space accessible to ligand bound homologues and how the presence of the ligand alters the conformational and dynamic properties of the protein.

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

Helfferich, Julian; Lyubimov, Ivan; Reid, Daniel

Glasses produced via physical vapor deposition can display greater kinetic stability and lower enthalpy than glasses prepared by liquid cooling. While the reduced enthalpy has often been used as a measure of the stability, it is not obvious whether dynamic measures of stability provide the same view. Here, we study dynamics in vapor-deposited and liquid-cooled glass films using molecular simulations of a bead-spring polymer model as well as a Lennard-Jones binary mixture in two and three dimensions. We confirm that the dynamics in vapor-deposited glasses is indeed slower than in ordinary glasses. We further show that the inherent structure energymore » is a good reporter of local dynamics, and that aged systems and glasses prepared by cooling at progressively slower rates exhibit the same behavior as vapor-deposited materials when they both have the same inherent structure energy. These findings suggest that the stability inferred from measurements of the energy is also manifested in dynamic observables, and they strengthen the view that vapor deposition processes provide an effective strategy for creation of stable glasses.« less

Nonlinear neural control with power systems applications

NASA Astrophysics Data System (ADS)

Chen, Dingguo

1998-12-01

Extensive studies have been undertaken on the transient stability of large interconnected power systems with flexible ac transmission systems (FACTS) devices installed. Varieties of control methodologies have been proposed to stabilize the postfault system which would otherwise eventually lose stability without a proper control. Generally speaking, regular transient stability is well understood, but the mechanism of load-driven voltage instability or voltage collapse has not been well understood. The interaction of generator dynamics and load dynamics makes synthesis of stabilizing controllers even more challenging. There is currently increasing interest in the research of neural networks as identifiers and controllers for dealing with dynamic time-varying nonlinear systems. This study focuses on the development of novel artificial neural network architectures for identification and control with application to dynamic electric power systems so that the stability of the interconnected power systems, following large disturbances, and/or with the inclusion of uncertain loads, can be largely enhanced, and stable operations are guaranteed. The latitudinal neural network architecture is proposed for the purpose of system identification. It may be used for identification of nonlinear static/dynamic loads, which can be further used for static/dynamic voltage stability analysis. The properties associated with this architecture are investigated. A neural network methodology is proposed for dealing with load modeling and voltage stability analysis. Based on the neural network models of loads, voltage stability analysis evolves, and modal analysis is performed. Simulation results are also provided. The transient stability problem is studied with consideration of load effects. The hierarchical neural control scheme is developed. Trajectory-following policy is used so that the hierarchical neural controller performs as almost well for non-nominal cases as they do for the nominal cases. The adaptive hierarchical neural control scheme is also proposed to deal with the time-varying nature of loads. Further, adaptive neural control, which is based on the on-line updating of the weights and biases of the neural networks, is studied. Simulations provided on the faulted power systems with unknown loads suggest that the proposed adaptive hierarchical neural control schemes should be useful for practical power applications.

Peritonitis following percutaneous gastrostomy tube insertions in children.

PubMed

Dookhoo, Leema; Mahant, Sanjay; Parra, Dimitri A; John, Philip R; Amaral, Joao G; Connolly, Bairbre L

2016-09-01

Percutaneous retrograde gastrostomy has a high success rate, low morbidity, and can be performed under different levels of sedation or local anesthesia in children. Despite its favourable safety profile, major complications can occur. Few studies have examined peritonitis following percutaneous retrograde gastrostomy in children. To identify potential risk factors and variables influencing the development and early diagnosis of peritonitis following percutaneous retrograde gastrostomy. We conducted a retrospective case-control study of children who developed peritonitis within 7 days of percutaneous retrograde gastrostomy between 2003 and 2012. From the 1,504 patients who underwent percutaneous retrograde gastrostomy, patients who developed peritonitis (group 1) were matched by closest date of procedure to those without peritonitis (group 2). Peritonitis was defined according to recognized clinical criteria. Demographic, clinical, procedural, management and outcomes data were collected. Thirty-eight of 1,504 children (2.5%; 95% confidence interval, 1.8-3.5) who underwent percutaneous retrograde gastrostomy developed peritonitis ≤7 days post procedure (group 1). Fever (89%), irritability (63%) and abdominal pain (55%) occurred on presentation of peritonitis. Group 1 patients were all treated with antibiotics; 41% underwent additional interventions: tube readjustments (8%), aspiration of pneumoperitoneum (23%), laparotomy (10%) and intensive care unit admission (10%). In group 1, enteral feeds started on average 3 days later and patients were discharged 5 days later than patients in group 2. There were two deaths not directly related to peritonitis. Neither age, gender, weight, underlying diagnoses nor operator was identified as a risk factor. Peritonitis following percutaneous retrograde gastrostomy in children occurs in approximately 2.5% of cases. No risk factors for its development were identified. Medical management is usually sufficient for a good outcome. Patients with peritonitis are delayed starting feeds and have a hospital stay that is an average of 5 days longer than those without.

Metatarsalgia and Morton's Disease: Comparison of Outcomes Between Open Procedure and Neurectomy Versus Percutaneous Metatarsal Osteotomies and Ligament Release With a Minimum of 2 Years of Follow-Up.

PubMed

Bauer, Thomas; Gaumetou, Elodie; Klouche, Shahnaz; Hardy, Philippe; Maffulli, Nicola

2015-01-01

The present study compared the clinical results of open neurectomy versus a percutaneous procedure for Morton's disease. This was a retrospective study comparing the functional results after 2 surgical procedures: open neurectomy and a percutaneous procedure (with deep transverse metatarsal ligament release and distal metatarsal osteotomies). The present study included 52 patients (26 in each group), and the mean follow-up period was 4 (range 2 to 7) years. The patient evaluation criteria included the presence of painful symptoms of Morton's disease, American Orthopaedic Foot and Ankle Society (AOFAS) functional scale score, patient satisfaction, and delay for recovery. Percutaneous treatment of Morton's disease and open neurectomy produced complete relief of pain in 25 of 26 patients in each group. At the latest follow-up visit, the mean AOFAS score had significantly improved from 36 ± 11 preoperatively to a mean of 89 ± 18 (p < .001). After 2 years, the functional improvement obtained with the percutaneous procedure persisted, with a stable AOFAS score (96 ± 10). Persistent metatarsalgia was reported by patients who had undergone open neurectomy, with a significantly decreased AOFAS score (81 ± 21, p = .009). The percutaneous procedure for Morton's disease provided excellent functional outcomes (AOFAS score >90) significantly more often with a shorter delay than after open neurectomy (p = .03). At the latest follow-up visit, metatarsalgia due to plantar hyperpressure or bursitis and requiring plantar orthotics was present in 11 of 26 patients (44%) after open neurectomy and in 1 of 26 patients (4%) after the percutaneous procedure (p = .002). Percutaneous treatment of Morton's disease is a reliable procedure providing results as good as those after open neurectomy, with significantly better outcomes in the longer term and a lower rate of late metatarsalgia. Copyright © 2015 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Lateral Stability and Steady State Curving Performance of Unconventional Rail Trucks

NASA Astrophysics Data System (ADS)

Dukkipati, Rao V.; Narayanaswamy, Srinivasan

Conventional railway vehicle systems exhibit hunting phenomenon which increases component wear and imposes operating speed limits. There is also a conflict between dynamic stability and the ability of the vehicle to steer around curves. Alternatively, independently rotating wheels (IRW) in a wheelset eliminate hunting but the wheelset guidance set capability is lost. A compromise solution is made possible by a modified design that exploits a lack of fore-and-aft symmetry in the suspension design. A comparative study on steady state curving performance and dynamic stability of some unconventional truck designs is carried out. The effects of suspension and conicity are considered to evaluate the trade-off between dynamic stability and curving performance.

Out-of-plane dynamic stability analysis of curved beams subjected to uniformly distributed radial loading

NASA Astrophysics Data System (ADS)

Sabuncu, M.; Ozturk, H.; Cimen; S.

2011-04-01

In this study, out-of-plane stability analysis of tapered cross-sectioned thin curved beams under uniformly distributed radial loading is performed by using the finite-element method. Solutions referred to as Bolotin's approach are analysed for dynamic stability, and the first unstable regions are examined. Out-of-plane vibration and out-of-plane buckling analyses are also studied. In addition, the results obtained in this study are compared with the published results of other researchers for the fundamental frequency and critical lateral buckling load. The effects of subtended angle, variations of cross-section, and dynamic load parameter on the stability regions are shown in graphics

Dynamics of an HBV/HCV infection model with intracellular delay and cell proliferation

NASA Astrophysics Data System (ADS)

Zhang, Fengqin; Li, Jianquan; Zheng, Chongwu; Wang, Lin

2017-01-01

A new mathematical model of hepatitis B/C virus (HBV/HCV) infection which incorporates the proliferation of healthy hepatocyte cells and the latent period of infected hepatocyte cells is proposed and studied. The dynamics is analyzed via Pontryagin's method and a newly proposed alternative geometric stability switch criterion. Sharp conditions ensuring stability of the infection persistent equilibrium are derived by applying Pontryagin's method. Using the intracellular delay as the bifurcation parameter and applying an alternative geometric stability switch criterion, we show that the HBV/HCV infection model undergoes stability switches. Furthermore, numerical simulations illustrate that the intracellular delay can induce complex dynamics such as persistence bubbles and chaos.

Dynamical stability of plutonium alloys

NASA Astrophysics Data System (ADS)

Torrent, Marc; Dorado, Boris; Bieder, Jordan

Plutonium sits at the center of the actinide series and marks the transition between localization and delocalization of the 5 f electrons. From a metallurgical standpoint, the monoclinic α phase (stable at low T) is brittle, not suitable for engineering applications, as opposed to the ductile fcc δ phase (stable at 580K). The δ - α transition can be avoided by alloying δ-Pu with ''deltagen'' elements. There is a wide unexplored area for Pu when it comes to lattice dynamics. Due to the changes in the composition, the dynamical stability of is constantly challenged. Displ. cascades are created in the material, which in turn produce numerous of point defects. Therefore, the accumulation of defects preclude a thermodynamic equilibrium. Given the importance for engineering applications, it is crucial that we understand the mechanisms that lead to stabilization with respect to the alloy composition. We use first-principles calculations to provide evidence of the effect of defects/impurities (C, O, Al, Fe, Ni, Ga, Ce, U, Am) on the dynamical stability of δ-Pu. We show that this phase is dynamically unstable at low T and that it depends on the 5 f orbital occupancies. We investigate how defects affect the stability by comparing the phonon DoS.

Reliability and Concurrent Validity of Dynamic Rotator Stability Test-A Cross Sectional study.

PubMed

Binoy Mathew, K V; Eapen, Charu; Kumar, P Senthil

2012-01-01

To find intra rater and inter rater reliability of Dynamic Rotator Stability Test (DRST) and to find concurrent validity of Dynamic Rotator Stability Test (DRST) with University of Pennsylvania Shoulder Score (PENN) Scale. 40 subjects of either gender between the age group of 18-70 with painful shoulder conditions of musculoskeletal origin was selected through convenient sampling. Tester 1 and tester 2 administered DRST and PENN scale randomly. In a subgroup of 20 subjects DRST was administered by both the testers to find the inter rater reliability. 180° Standard Universal Goniometer was used to take measurements. For intra-rater reliability, all the test variables were showing highly significant correlation (p=.94 - 1). For inter -rater, with tester 2, test variables like position, ROM, force, direction of abnormal translation, pain during the test, compensatory movement during test were found to be significant (p=.71-1).only some variables of DRST showed significant correlation with PENN scale (P=.320-.450). Dynamic Rotator Stability Test has good intra rater and moderate inter rater reliability. Concurrent validity of Dynamic Rotator Stability Test was found to be poor when compared to PENN Shoulder Score.

Comparison of jump-landing protocols with Biodex Balance System as measures of dynamic postural stability in athletes.

PubMed

Krkeljas, Zarko

2017-07-21

The objective of the study was to determine whether a relationship exists between the two common methods for assessing postural stability in athletes: the time-to-stabilisation (TTS) via force-plate and the Biodex Balance System (BBS). The conditions under which these measurements assess dynamic postural control may not provide sufficient feedback to practitioners. Fourty-four amateur soccer players with no history of musculoskeletal disorders volunteered for the study. Pearson correlation was used to compare the anterior-posterior (AP), medio-lateral (ML), and the overall stability indexes measured by BBS, with the corresponding parameters of TTS assessed via force plate. There was no significant correlation between any parameters of dynamic stability measured by force-plate and the stability indexes. However, there was a significant correlation between the resulting vectors and the AP component of TTS for each jump protocol. Furthermore, forward drop landing exhibited shortest TTS in AP direction, while lateral drop landing resulted in longer ML TTS relative to both forward jumps (p < 0.001). These results demonstrate that the TTS and BBS stability indexes should be used as distinct measures of dynamic postural stability. TTS protocols may be modified to target a specific training conditions or athletic population.

Rotorcraft aeroelastic stability

NASA Technical Reports Server (NTRS)

Ormiston, Robert A.; Warmbrodt, William G.; Hodges, Dewey H.; Peters, David A.

1988-01-01

Theoretical and experimental developments in the aeroelastic and aeromechanical stability of helicopters and tilt-rotor aircraft are addressed. Included are the underlying nonlinear structural mechanics of slender rotating beams, necessary for accurate modeling of elastic cantilever rotor blades, and the development of dynamic inflow, an unsteady aerodynamic theory for low-frequency aeroelastic stability applications. Analytical treatment of isolated rotor stability in hover and forward flight, coupled rotor-fuselage stability in hover and forward flight, and analysis of tilt-rotor dynamic stability are considered. Results of parametric investigations of system behavior are presented, and correlation between theoretical results and experimental data from small and large scale wind tunnel and flight testing are discussed.

Botulinum toxin injection - larynx

MedlinePlus

Injection laryngoplasty; Botox - larynx: spasmodic dysphonia-BTX; Essential voice tremor (EVT)-btx; Glottic insufficiency; Percutaneous electromyography - guided botulinum toxin treatment; Percutaneous indirect laryngoscopy - guided botulinum toxin treatment; ...

Intraoperative fluoroscopic evaluation of screw placement during pelvic and acetabular surgery.

PubMed

Yi, Chengla; Burns, Sean; Hak, David J

2014-01-01

The surgical treatment of pelvic and acetabular fractures can be technically challenging. Various techniques are available for the reconstruction of pelvic and acetabular fractures. Less invasive percutaneous fracture stabilization techniques, with closed reduction or limited open reduction, have been developed and are gaining popularity in the management of pelvic and acetabular fractures. These techniques require knowledge and interpretation of various fluoroscopic images to ensure appropriate and safe screw placement. Given the anatomic complexity of the intrapelvic structures and the 2-dimensional nature of standard fluoroscopy, multiple images oriented in different planes are needed to assess the accuracy of guide wire and screw placement. This article reviews the fluoroscopic imaging of common screw orientations during pelvic and acetabular surgery.

Dynamic stability of electrodynamic maglev systems

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

Cai, Y.; Chen, S.S.; Mulcahy, T.M.

1997-01-01

Because dynamic instabilities are not acceptable in any commercial maglev system, it is important to consider dynamic instability in the development of all maglev systems. This study considers the stability of maglev systems based on mathematical models and experimental data. Divergence and flutter are obtained for coupled vibration of a three-degree-of-freedom maglev vehicle on a guideway consisting of double L-shaped aluminum segments. The theory and analysis for motion-dependent magnetic-force-induced instability developed in this study provides basic stability characteristics and identifies future research needs for maglev systems.

European Workshop on Planetary Sciences, Rome, Italy, April 23-27, 1979, Proceedings. Part 1

NASA Astrophysics Data System (ADS)

1980-02-01

Papers are presented on the dynamics and evolution of the solar system and its components. Specific topics include the dynamic stability of the solar system, the tidal friction theory of the earth moon system, the stability and irregularity of extrasolar planetary systems, angular momentum and magnetic braking during star formation, the collisional growth of planetesimals, the dynamics, interrelations and evolution of the asteroids and comets, the formation and stability of Saturn's rings, and the importance of nearly tangent orbits in planetary close encounters.

High-Flow Arteriovenous Malformation of the Lower Extremity: Ethanolamine Oleate Sclerotherapy

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

Hyodoh, Hideki; Fujita, Akifumi; Hyodoh, Kazusa

2001-09-15

We report the case of a young man presenting with high-flow arteriovenous malformation (AVM), in whom percutaneous direct nidus puncture ethanolamine oleate (EO) sclerotherapy was useful in the management of the AVM. To our knowledge, this is the first report of percutaneous trans-nidus EO sclerotherapy for AVM in the extremities. Percutaneous trans-nidus sclerotherapy should be considered as an alternative choice for the management of symptomatic AVM.

Palliative percutaneous transhepatic drainage for inoperable obstructive jaundice.

PubMed Central

Baxter-Smith, D. C.; Temple, J. G.; Howarth, F.

1982-01-01

A technique of percutaneous transhepatic drainage under local anaesthesia is described for the relief of intractable pruritus in patients with obstructive jaundice due to inoperable carcinoma. After standard percutaneous transhepatic cholangiography a polyethylene catheter is introduced into one of the large dilated bile ducts and left in situ, thereby establishing external retrograde biliary drainage. The technique has been used successfully in 6 cases with reduction in serum bilirubin levels and relief of pruritus. PMID:6182832

[Percutaneous endoscopic gastrostomy].

PubMed

Kuz'min-Krutetskiĭ, M I; Demko, A E; Safoev, A I; Akkalaeva, A É; Karimova, L I

2014-01-01

The percutaneous endoscopic gastrostomy takes an important place in operative endoscopy of the digestive system. At the same time it is the method of choice in patients who need a long-term administration of enteral feeding. Given article reflects the main indications, contraindications and complications of the percutaneous endoscopic gastrostomy and presents the basic stages of the method. The authors hope, that the data would be useful for both entry-lever surgeon-endoscopists and specialists who used the method.

Effect of aging on dynamic postural stability and variability during a multi-directional lean and reach object transportation task.

PubMed

Huntley, Andrew H; Zettel, John L; Vallis, Lori Ann

2016-01-01

A "reach and transport object" task that represents common activities of daily living may provide improved insight into dynamic postural stability and movement variability deficits in older adults compared to previous lean to reach and functional reach tests. Healthy young and older, community dwelling adults performed three same elevation object transport tasks and two multiple elevation object transport tasks under two self-selected speeds, self-paced and fast-paced. Dynamic postural stability and movement variability was quantified by whole-body center of mass motion. Older adults demonstrated significant decrements in frontal plane stability during the multiple elevation tasks while exhibiting the same movement variability as their younger counterparts, regardless of task speed. Interestingly, older adults did not exhibit a tradeoff in maneuverability in favour of maintaining stability throughout the tasks, as has previously been reported. In conclusion, the multi-planar, ecologically relevant tasks employed in the current study were specific enough to elucidate decrements in dynamic stability, and thus may be useful for assessing fall risk in older adults with suspected postural instability. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Dynamic Stabilization of Simple Fractures With Active Plates Delivers Stronger Healing Than Conventional Compression Plating

PubMed Central

Tsai, Stanley; Bliven, Emily K.; von Rechenberg, Brigitte; Kindt, Philipp; Augat, Peter; Henschel, Julia; Fitzpatrick, Daniel C.; Madey, Steven M.

2017-01-01

Objectives: Active plates dynamize a fracture by elastic suspension of screw holes within the plate. We hypothesized that dynamic stabilization with active plates delivers stronger healing relative to standard compression plating. Methods: Twelve sheep were randomized to receive either a standard compression plate (CP) or an active plate (ACTIVE) for stabilization of an anatomically reduced tibial osteotomy. In the CP group, absolute stabilization was pursued by interfragmentary compression with 6 cortical screws. In the ACTIVE group, dynamic stabilization after bony apposition was achieved with 6 elastically suspended locking screws. Fracture healing was analyzed weekly on radiographs. After sacrifice 9 weeks postsurgery, the torsional strength of healed tibiae and contralateral tibiae was measured. Finally, computed tomography was used to assess fracture patterns and healing modes. Results: Healing in both groups included periosteal callus formation. ACTIVE specimens had almost 6 times more callus area by week 9 (P < 0.001) than CP specimens. ACTIVE specimens recovered on average 64% of their native strength by week 9, and were over twice as strong as CP specimens, which recovered 24% of their native strength (P = 0.008). Microcomputed tomography demonstrated that compression plating induced a combination of primary bone healing and gap healing. Active plating consistently stimulated biological bone healing by periosteal callus formation. Conclusions: Compared with compression plating, dynamic stabilization of simple fractures with active plates delivers significantly stronger healing. PMID:27861456

Interplay Between Energy-Market Dynamics and Physical Stability of a Smart Power Grid

NASA Astrophysics Data System (ADS)

Picozzi, Sergio; Mammoli, Andrea; Sorrentino, Francesco

2013-03-01

A smart power grid is being envisioned for the future which, among other features, should enable users to play the dual role of consumers as well as producers and traders of energy, thanks to emerging renewable energy production and energy storage technologies. As a complex dynamical system, any power grid is subject to physical instabilities. With existing grids, such instabilities tend to be caused by natural disasters, human errors, or weather-related peaks in demand. In this work we analyze the impact, upon the stability of a smart grid, of the energy-market dynamics arising from users' ability to buy from and sell energy to other users. The stability analysis of the resulting dynamical system is performed assuming different proposed models for this market of the future, and the corresponding stability regions in parameter space are identified. We test our theoretical findings by comparing them with data collected from some existing prototype systems.

Distinct single-cell morphological dynamics under beta-lactam antibiotics

PubMed Central

Yao, Zhizhong; Kahne, Daniel; Kishony, Roy

2012-01-01

Summary The bacterial cell wall is conserved in prokaryotes, stabilizing cells against osmotic stress. Beta-lactams inhibit cell wall synthesis and induce lysis through a bulge-mediated mechanism; however, little is known about the formation dynamics and stability of these bulges. To capture processes of different timescales, we developed an imaging platform combining automated image analysis with live cell microscopy at high time resolution. Beta-lactam killing of Escherichia coli cells proceeded through four stages: elongation, bulge formation, bulge stagnation and lysis. Both the cell wall and outer membrane (OM) affect the observed dynamics; damaging the cell wall with different beta-lactams and compromising OM integrity cause different modes and rates of lysis. Our results show that the bulge formation dynamics is determined by how the cell wall is perturbed. The OM plays an independent role in stabilizing the bulge once it is formed. The stabilized bulge delays lysis, and allows recovery upon drug removal. PMID:23103254

Model of a Frame of Dynamic Routing and Its Equilibrium

NASA Astrophysics Data System (ADS)

Zhang, Shu; Yuan, Yuan; Xu, Jian

Dynamic routing algorithm based on the shortest path principle is criticized due to the oscillation induced by such routing scheme. In the present work, we propose the model of TCP/RED algorithm by a new frame of dynamic routing, based on the measurement of occupation ratio of router buffer for different links, which only requires the information of the queue size at the buffer of the router, to stabilize the system. We classify several types of equilibrium and employ the numerical method to study the stability of the steady state. Our numerical results show that the careful selection of the parameters characterizing the dynamic routing algorithm can stabilize the system in some cases.

Subsonic Dynamic Stability Tests of a Sample Return Entry Vehicle

NASA Technical Reports Server (NTRS)

Fremaux, C. Michael; Johnson, R. Keith

2006-01-01

An investigation has been conducted in the NASA Langley 20-Foot Vertical Spin Tunnel (VST) to determine the subsonic dynamic stability characteristics of a proposed atmospheric entry vehicle for sample return missions. In particular, the effects of changes in aft-body geometry on stability were examined. Freeflying tests of a dynamically scaled model with various geometric features were conducted, including cases in which the model was perturbed to measure dynamic response. Both perturbed and non-perturbed runs were recorded as motion time histories using the VST optical data acquisition system and reduced for post-test analysis. In addition, preliminary results from a static force and moment test of a similar model in the Langley 12-Foot Low Speed Tunnel are presented. Results indicate that the configuration is dynamically stable for the baseline geometry, but exhibits degraded dynamic behavior for the geometry modifications tested.

Experimental Waterflow Determination of the Dynamic Hydraulic Transfer Function for the J-2X Oxidizer Turbopump. Part Two; Results and Interpretation

NASA Technical Reports Server (NTRS)

Zoladz, Tom; Patel, Sandeep; Lee, Erik; Karon, Dave

2011-01-01

Experimental results describing the hydraulic dynamic pump transfer matrix (Yp) for a cavitating J-2X oxidizer turbopump inducer+impeller tested in subscale waterflow are presented. The transfer function is required for integrated vehicle pogo stability analysis as well as optimization of local inducer pumping stability. Dynamic transfer functions across widely varying pump hydrodynamic inlet conditions are extracted from measured data in conjunction with 1D-model based corrections. Derived Dynamic transfer functions are initially interpreted relative to traditional Pogo pump equations. Water-to-liquid oxygen scaling of measured cavitation characteristics are discussed. Comparison of key dynamic transfer matrix terms derived from waterflow testing are made with those implemented in preliminary Ares Upper Stage Pogo stability modeling. Alternate cavitating pump hydraulic dynamic equations are suggested which better reflect frequency dependencies of measured transfer matrices.

Role of percutaneous abscess drainage in the management of young patients with Crohn disease.

PubMed

Pugmire, Brian S; Gee, Michael S; Kaplan, Jess L; Hahn, Peter F; Doody, Daniel P; Winter, Harland S; Gervais, Debra A

2016-05-01

Intra-abdominal abscess is a common complication of Crohn disease in children. Prior studies, primarily in adults, have shown that percutaneous abscess drainage is a safe and effective treatment for this condition; however, the data regarding this procedure and indications in pediatric patients is limited. Our aim was to determine the success rate of percutaneous abscess drainage for abscesses related to Crohn disease in pediatric patients with a focus on treatment endpoints that are relevant in the era of biological medical therapy. We retrospectively reviewed 25 cases of patients ages ≤20 years with Crohn disease who underwent percutaneous abscess drainage. Technical success was defined as catheter placement within the abscess with reduction in abscess size on post-treatment imaging. Clinical success was defined as (1) no surgery within 1 year of drainage or (2) surgical resection following drainage with no residual abscess at surgery or on preoperative imaging. Multiple clinical parameters were analyzed for association with treatment success or failure. All cases were classified as technical successes. Nineteen cases were classified as clinical successes (76%), including 7 patients (28%) who required no surgery within 1 year of percutaneous drainage and 12 patients (48%) who had elective bowel resection within 1 year. There was a statistically significant association between resumption of immunosuppressive therapy within 8 weeks of drainage and both clinical success (P < 0.01) and avoidance of surgery after 1 year (P < 0.01). Percutaneous abscess drainage is an effective treatment for Crohn disease-related abscesses in pediatric patients. Early resumption of immunosuppressive therapy is statistically associated with both clinical success and avoidance of bowel resection, suggesting a role for percutaneous drainage in facilitating prompt initiation of medical therapy and preventing surgical bowel resection.

Realtime ultrasound guided percutaneous tracheostomy in emergency setting: the glass ceiling has been broken.

PubMed

Ravi, Parli Raghavan; Vijai, M N; Shouche, Sachin

2017-01-01

In recent years ultrasound guided percutaneous tracheostomy (USPCT) has become a routine practice in critical care units. Its safety and superiority over conventional percutaneous tracheostomy and bronchoscopic guided PCT is proven to be non-inferior in elective cases. However its role in emergency percutaneous tracheostomy has never been studied, since percutaneous tracheostomy itself remains an enigma in accessing emergency airway. There is no report of use of ultrasound guided percutaneous tracheostomy in emergency setting so far in the literature. We report our early experience with USPCT in emergency setting. Sixteen adult patients who required access to an emergency surgical airway after failure to accomplish emergency oro-tracheal intubation were the study population. Their airway was accessed by USPCT. Recorded data included clinical and demographic data including time taken to perform the procedure and complications. Short term and long term follow ups for a period of 2 years were done for the survivors. Twelve male and four female patients underwent the procedure and the average time of the procedure was 3.6 min with no failures nor conversions to surgical tracheostomy and no complications. The average oxygen saturation was 86% and average Glasgow coma scale was 8.4. This time period included the oxygen insufflation time. 10 patients were decannulated while six patients died due to the pathology of the disease itself. There were no complications in either short term or long term follow up. USPCT has a definitive role in emergency both in trauma and non-trauma setting. It is safe, feasible and faster in experienced hands. Use of USPCT in emergency setting has further narrowed the list of contraindications of percutaneous tracheostomy.

Comparison of transradial and transfemoral artery approach for percutaneous coronary angiography and angioplasty: a retrospective seven-year experience from a north Indian center.

PubMed

Tewari, Satyendra; Sharma, Naveen; Kapoor, Aditya; Syal, Sanjeev Kumar; Kumar, Sudeep; Garg, Naveen; Goel, Pravin K

2013-01-01

With the increasing prevalence of coronary artery disease, percutaneous coronary artery procedures have become even more important. Our study has compared transradial to transfemoral artery approach for coronary procedures in Indian population. Comparison of transradial and transfemoral artery approach for percutaneous coronary procedures. 26,238 patients, who underwent percutaneous coronary artery procedures, were divided into two groups depending upon transradial and transfemoral artery approach and compared for the various demographic and clinical characteristics, risk factors profile, vascular access and procedural details. 26,238 patients underwent percutaneous coronary procedures at our center. 81% were male and 19% were female. 55.65% and 44.35% procedures were done through transfemoral and transradial approach, respectively. 17,417 (66.38%) coronary angiographies were done, out of which 53.92% were transradial and 46.08% were transfemoral procedures. 8821 (33.62%) Percutaneous Transluminal Coronary Angioplasty (PTCA) were done, out of which 25.46% and 74.54% were done through transradial and transfemoral approach, respectively. Mean fluoroscopy time was 4.40 ± 3.55 min for transradial and 3.30 ± 3.66 min for transfemoral CAG (p < 0.001). For PTCA mean fluoroscopy time was 13.53 ± 2.53 min for transradial and 12.61 ± 9.524 min for transfemoral PTCA (p < 0.001). Minor and major procedure related complications and total duration of hospital stay were lower in transradial as compared to transfemoral group. The number of percutaneous transradial procedures have increased significantly with reduced complication rates and comparable success rate to transfemoral approach, along with the additional benefits to patient in terms of patient comfort, preference and reduced cost of health delivery. Copyright © 2013 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

Comparative investigation of percutaneous plating and intramedullary nailing effects on IL-6 production in patients with tibia shaft fracture.

PubMed

Ebrahimpour, Adel; Okhovatpour, Mohammad-Ali; Sadighi, Mehrdad; Sarejloo, Amir-Hossein; Sajjadi, Mohammad-Reza Minator

2017-12-01

The aim of this study was to analyze the effect of intramedullary nailing (IMN), open plating and percutaneous plating on the induction of IL-6 in patients with tibia fractures. A total of 30 patients with tibia shaft fracture underwent either intramedullary nailing (IMN, n = 15; 14 males and 1 female; mean age: 32.1 ± 15.6), ORIF plating (n = 8; 5 males and 3 females; mean age: 60.0 ± 17.8), or percutaneous plating (n = 7; 6 males and 1 female; mean age: 43.1 ± 21.4). Serum IL-6 cytokine levels were measured prior to, and 6 and 24 h after the surgery, using a special ELISA kit. The IL-6 concentration increased to peak levels at 6 h in both IMN and percutaneous plating groups, and at 24 h in ORIF plating group (p < 0.001). The mean IL-6 concentration of percutaneous plating group was significantly lower than that of the IMN group at 6 h following the surgery (p = 0.022). In addition, the mean IL-6 concentration of ORIF plating group was significantly higher than that of the percutaneous plating group at 24 h post operation (p = 0.009). Our results suggest that percutaneous plating compared to the IMN has lower effects on IL-6 production in patients with tibia fracture. Level III, therapeutic study. Copyright © 2017 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

Percutaneous injuries among dental professionals in Washington State

PubMed Central

Shah, Syed M; Merchant, Anwar T; Dosman, James A

2006-01-01

Background Percutaneous exposure incidents facilitate transmission of bloodborne pathogens such as human immunodeficiency virus (HIV), hepatitis C virus (HCV) and hepatitis B virus (HBV). This study was conducted to identify the circumstances and equipment related to percutaneous injuries among dental professionals. Methods We used workers' compensation claims submitted to the Department of Labor and Industries State Fund during a 7-year period (1995 through 2001) in Washington State for this study. We used the statement submitted by the injured worker on the workers' compensation claim form to determine the circumstances surrounding the injury including the type of activity and device involved. Results Of a total of 4,695 accepted State Fund percutaneous injury claims by health care workers (HCWs), 924 (20%) were submitted by dental professionals. Out of 924 percutaneous injuries reported by dental professionals 894 (97%) were among dental health care workers in non-hospital settings, including dentists (66, 7%), dental hygienists (61, 18%) and dental assistants (667, 75%). The majority of those reporting were females (638, 71%). Most (781, 87%) of the injuries involved syringes, dental instruments (77, 9%), and suture needles (23%). A large proportion (90%) of injuries occurred in offices and clinics of dentists, while remainder occurred in offices of clinics and of doctors of medicine (9%), and a few in specialty outpatient facilities (1%). Of the 894 dental health care workers with percutaneous injuries, there was evidence of HBV in 6 persons, HCV in 30 persons, HIV in 3 persons and both HBV and HVC (n = 2) exposure. Conclusion Out of hospital percutaneous injuries are a substantial risk to dental health professionals in Washington State. Improved work practices and safer devices are needed to address this risk. PMID:17074095

Percutaneous closure of patent ductus arteriosus in small infants with significant lung disease may offer faster recovery of respiratory function when compared to surgical ligation.

PubMed

Abu Hazeem, Anas A; Gillespie, Matthew J; Thun, Haley; Munson, David; Schwartz, Matthew C; Dori, Yoav; Rome, Jonathan J; Glatz, Andrew C

2013-10-01

To describe our experience with percutaneous closure of patent ductus arteriosus (PDA) in small infants and compare outcomes to matched surgical patients. Ligation via thoracotomy has been used to close PDAs in small infants, but has been associated with respiratory and hemodynamic compromise. We hypothesized that percutaneous closure would offer faster recovery of respiratory function. Patients <4 kg requiring positive pressure ventilation who underwent percutaneous PDA closure between January 2000 and April 2012 were reviewed and matched to contemporary surgical patients on gestational age (GA), birth weight (BW), procedure weight (WT), and ventilation mode. Patients returned to baseline respiratory status when the product of mean airway pressure and FiO2 returned to pre-procedural levels. Eight matched pairs were included. Median BW, GA, and WT were 1.43 kg (0.52-2.97), 29.8 weeks (24-39), and 2.8 kg (2.2-3.9) for catheter patients and 1.55 kg (0.48-3.04), 29 weeks (23-37), and 2.75 kg (2.3-4.2) for surgical patients. Complete PDA closure occurred in all. The median time to return to baseline respiratory status was significantly shorter in the percutaneous group (17 hr (range 0-113) vs. 53 hr (range 13-219), P < 0.05). In the percutaneous group, two patients developed mild aortic coarctation, one mild left pulmonary artery stenosis, and four femoral vascular thromboses which all resolved with medical therapy. Surgical complications included significant respiratory and cardiac compromise, rib fractures and urinary retention. Percutaneous closure of PDA in small infants on respiratory support is equivalent in safety and efficacy and may offer shorter recovery time than surgical ligation. Copyright © 2013 Wiley Periodicals, Inc.

Maintenance percutaneous posterior nerve stimulation for refractory lower urinary tract symptoms in patients with multiple sclerosis: an open label, multicenter, prospective study.

PubMed

Zecca, C; Digesu, G A; Robshaw, P; Singh, A; Elneil, S; Gobbi, C

2014-03-01

Percutaneous tibial nerve stimulation is an effective second line therapy for lower urinary tract symptoms. Data on percutaneous tibial nerve stimulation maintenance treatment are scarce. In this study we evaluate its effectiveness and propose an algorithm of percutaneous tibial nerve stimulation maintenance treatment in patients with multiple sclerosis. In this prospective, multicenter, open label trial consecutive patients with multiple sclerosis and lower urinary tract symptoms unresponsive to medical therapy were treated with 12 weekly sessions of percutaneous tibial nerve stimulation. Responder patients (50% or greater improvement of lower urinary tract symptoms as measured by the patient perception of bladder condition questionnaire) entered a maintenance phase with individualized treatment frequency based on patient response. Lower urinary tract symptoms were assessed using a 3-day frequency volume chart, urodynamics and patient perception of bladder condition questionnaire. Treatment satisfaction was evaluated using a global response assessment scale and a treatment satisfaction visual analog scale. A total of 83 patients were included in the study and 74 (89%) responded to initial treatment. Persistent efficacy occurred in all initial responders after a mean treatment of 24 months. The greatest frequency of maintenance percutaneous tibial nerve stimulation was every 2 weeks. Lower urinary tract symptoms and patient treatment satisfaction improved with time compared to initial treatment (p <0.05). Bladder diary parameters and voiding parameters improved compared to baseline (p <0.05). Prolonged percutaneous tibial nerve stimulation treatment leads to a persistent improvement of lower urinary tract symptoms in patients with multiple sclerosis. Copyright © 2014 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Percutaneous biliary approach as a successful rescue procedure after failed endoscopic therapy for drainage in advanced hilar tumors.

PubMed

Jang, Sung Ill; Hwang, Jin-Hyeok; Lee, Kwang-Hun; Yu, Jeong-Sik; Kim, Hee Wook; Yoon, Chang Jin; Lee, Yoon Suk; Paik, Kyu Hyun; Lee, Sang Hyub; Lee, Dong Ki

2017-04-01

Palliative endoscopic or percutaneous biliary drainage is used for unresectable advanced hilar cancer (HC). The best option for drainage in Bismuth type III or IV HC has not been established. The aims of this study are to identify factors predictive of endoscopic stenting failure and evaluate the effectiveness of rescue percutaneous stenting in patients with advanced HC. Data from 110 patients with inoperable advanced HC were retrospectively reviewed. All received bilateral self-expandable metallic stents. Patients were divided into three groups: I, successful initial endoscopic stenting; II, unsuccessful initial endoscopic stenting, followed by percutaneous stenting; and III, initial percutaneous stenting. We analyzed clinical results and radiologic tumor characteristics. Baseline characteristics and clinical outcomes of all groups were similar, except the hospital stay was longer in group III than group I. Technical success rate was higher in groups II and III (100%) than in group I (72.4%). The functional success rate, stent patency time, patient survival time, and complication rate were similar between groups. Endoscopic stenting failed because of guide-wire passage failure (n = 12) or stent passage failure (n = 7). The only factor significantly associated with endoscopic failure was a smaller left intrahepatic duct-common bile duct angle. As clinical outcomes were generally similar between approaches, percutaneous stenting is recommended for patients with Bismuth type III or IV advanced HC. Acute left intrahepatic duct-common bile duct angulation predicts endoscopic stenting failure. If endoscopic stenting fails, immediate conversion to the percutaneous approach is a necessary and effective rescue method. © 2016 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

Nanodesign of olein vesicles for the topical delivery of the antioxidant resveratrol.

PubMed

Pando, Daniel; Caddeo, Carla; Manconi, Maria; Fadda, Anna Maria; Pazos, Carmen

2013-08-01

The ex-vivo percutaneous absorption of the natural antioxidant resveratrol in liposomes and niosomes was investigated. The influence of vesicle composition on their physicochemical properties and stability was evaluated. Liposomes containing resveratrol were formulated using soy phosphatidylcholine (Phospholipon90G). Innovative niosomes were formulated using mono- or diglycerides: glycerol monooleate (Peceol) and polyglyceryl-3 dioleate (Plurol OleiqueCC), respectively, two suitable skin-compatible oleins used in pharmaceutical formulations as penetration enhancers. Small, negatively charged vesicles with a mean size of approximately 200 nm were prepared. The accelerated stability of vesicles was evaluated using Turbiscan Lab Expert, and the bilayer deformability was also assessed. Ex-vivo transdermal experiments were carried out in Franz diffusion cells, on newborn pig skin, to study the influence of the different vesicle formulations on resveratrol skin delivery. Results indicated a high cutaneous accumulation and a low transdermal delivery of resveratrol, especially when Peceol niosomes were used. Overall, niosomes formulated with Plurol oleique or Peceol showed a better behaviour than liposomes in the cutaneous delivery of resveratrol. © 2013 Royal Pharmaceutical Society.

Evidence-based medicine in metastatic spine disease.

PubMed

Dea, Nicolas; Fisher, Charles G

2014-06-01

Treatment modalities for metastatic spine disease have significantly expanded over the last two decades. This expansion occurred in many different fields. Improvement in surgical techniques and instrumentation now allow the oncologic spine surgeons to effectively circumferentially decompress the neural elements without compromising stability. Percutaneous techniques, both vertebral augmentation and pre-operative endovascular embolization procedures, also greatly benefit patients suffering from spinal column metastasis. Imaging technology advances has contributed to better pre-operative planning and the development of highly conformational radiation techniques, thus permitting the delivery of high-dose radiation to tumors, while avoiding radiotoxicity to the spinal cord and other vital structures. These new developments, combined with evidence-based stability and disease-specific quality of life scores now allow not only better treatment, but also a solid foundation for high-quality research. Spine oncology literature currently suffers from a lack of high-quality evidence due to low prevalence of the disease and complex methodological issues. However, when following evidence-based medicine principles, which incorporate best available evidence, clinical expertise and patient preference, sound, evidence-based recommendations can be made regarding the abovementioned treatment modalities.

Temporal changes in the outcomes of patients with diabetes mellitus undergoing percutaneous coronary intervention in the National Heart, Lung, and Blood Institute dynamic registry.

PubMed

Holper, Elizabeth M; Abbott, J Dawn; Mulukutla, Suresh; Vlachos, Helen; Selzer, Faith; McGuire, Darren; Faxon, David P; Laskey, Warren; Srinivas, Vankeepuram S; Marroquin, Oscar C; Jacobs, Alice K

2011-02-01

Patients with diabetes mellitus (DM) are at higher risk for adverse outcomes following percutaneous coronary intervention (PCI). To determine whether outcomes have improved over time, we analyzed data from 2,838 consecutive patients with medically treated DM, including 1,066 patients (37.6%) treated with insulin, in the National Heart, Lung, and Blood Institute Dynamic Registry undergoing PCI registered in waves 1 (1997-1998), 2 (1999), 3 (2001-2002), 4 (2004), and 5 (2006). We compared baseline demographics and 1-year outcomes in the overall cohort and in analyses stratified by recruitment wave and insulin use. Crude mortality rates by chronological wave were 9.5%, 12.5%, 8.9%, 11.6%, and 6.6% (P value(trend) = .33) among those treated with insulin and, respectively, 9.7%, 6.5%, 4.1%, 5.4%, and 4.7% (P value(trend) = .006) among patients treated with oral agents,. The adjusted hazard ratios of death, myocardial infarction (MI), and overall major adverse cardiovascular events (death, MI, revascularization) in insulin-treated patients with DM in waves 2 to 5 as compared with wave 1 were either higher or the same. In contrast, the similar adjusted hazard ratios for oral agent-treated patients with DM were either similar or lower. Significant improvements over time in adverse events by 1 year were detected in patients with DM treated with oral agents. In insulin-treated diabetic patients, despite lower rates of repeat revascularization over time, death and MI following PCI have not significantly improved. These findings underscore the need for continued efforts at optimizing outcomes among patients with DM undergoing PCI, especially those requiring insulin treatment. Copyright © 2011 Mosby, Inc. All rights reserved.

Angioscopy by a new percutaneous transluminal coronary angioscope

NASA Astrophysics Data System (ADS)

Sakurada, Masami; Mizuno, Kyoichi; Miyamoto, Akira; Arakawa, Koh; Satomura, Kimio; Shibuya, Toshio; Yanagida, Shigeki; Okamoto, Yasuyuki; Kurita, Akira; Nakamura, Haruo; Arai, Tsunenori; Suda, Akira; Kikuchi, Makoto; Utsumi, Atsushi; Takeuchi, Kiyoshi; Akai, Yoshiro

1990-07-01

We developed a new percutaneous transluminal coronary angioscopic catheter for visualization of coronary artery.This angioscopic catheter has an inflatable balloon at the distal tip and one - directional angulation mechanism.We performed percutaneous transluminal coronary angioscopy during cardiac catheterization cosecutively in 155 patients. With this angioscope , we could get good'-'fair visualization in 81%(131 of 162 lesions)without major complications.We could investigate the endothelial macropathology of ischemic heart disease such as unstable angina and acute myocardial infarction.

Percutaneous Pancreatic Stent Placement for Postoperative Pancreaticojejunostomy Stenosis: A Case Report

PubMed Central

Yang, Seung Koo

2016-01-01

Stenosis of the pancreatico-enteric anastomosis is one of the major complications of pancreaticoduodenectomy (PD). Endoscopic stent placement, has limited success rate as a nonsurgical treatment due to altered gastrointestinal anatomy. Percutaneous treatment is rarely attempted due to the technical difficulty in accessing the pancreatic duct. We reported a case of pancreaticojejunostomy stenosis after PD, in which a pancreatic stent was successfully placed using a rendezvous technique with a dual percutaneous approach. PMID:27587970

Weaknesses in regional primary coronary angioplasty programs: is there still a role for a pharmaco-invasive approach?

PubMed

Danchin, Nicolas; Dos Santos Teixeira, Nelson; Puymirat, Etienne

2014-08-01

All guidelines recommend primary percutaneous coronary intervention as the default strategy for achieving reperfusion in ST-segment elevation myocardial infarction patients. These recommendations are based upon randomized trials which compared primary percutaneous coronary intervention with stand-alone intravenous fibrinolysis. Since the time these trials were performed, however, it has been shown in further trials that use of rescue percutaneous coronary intervention in patients without signs of reperfusion after lysis, and routine coronary angiography within 24 h of the administration of lysis for all other patients, substantially improved the results of intravenous fibrinolytic treatment. This has led to proposing the pharmaco-invasive strategy as an alternative to primary percutaneous coronary intervention. Actually, it is not uncommon that circumstances prevent performing primary percutaneous coronary intervention within the recommended time limits set by the guidelines. In such cases, using a pharmaco-invasive strategy may constitute a valid alternative. Both the STREAM randomized trial and real-world experience, in particular the long-term results from the FAST-MI registry, suggest that the pharmaco-invasive strategy, when used in an appropriate population, compares favorably with primary percutaneous coronary intervention. Therefore, implementing a pharmaco-invasive strategy protocol may be an important complement to compensate for potential weaknesses in ST-segment elevation myocardial infarction networks. Copyright © 2014 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

The current role of percutaneous chemolysis in the management of urolithiasis: review and results.

PubMed

Kachrilas, Stefanos; Papatsoris, Athanasios; Bach, Christian; Bourdoumis, Andreas; Zaman, Faruquz; Masood, Junaid; Buchholz, Noor

2013-08-01

The treatment of urolithiasis has changed dramatically over the past several decades. Novel technologies have led to new management protocols. Percutaneous chemolysis as a primary or adjuvant treatment for urinary tract stones has widely been neglected. We present our own experience with it and discuss it in the light of an extensive literature review. From a MEDLINE search on percutaneous chemolysis we evaluated the most important studies, a total of 58 articles, 43 case series and 15 review articles. In our unit between 2001 and 2011, 29 patients (mean age 62 years) with infectious staghorn calculi were treated with adjuvant percutaneous chemolysis post-percutaneous nephrolithotripsy. There were 17 women, with 10 complete and 14 partial staghorn stones (mean size 32 mm). Patients were generally deemed at high risk to undergo another procedure in the future. Suby G solution was used following an established protocol. Sixteen patients (55.1 %) were stone free after chemolysis, eight stones showed partial dissolution, half of them with so-called "insignificant" residual fragments <4 mm. Patients with residual stones underwent SWL. Mean follow-up was 5.25 years (1-11). One stone-free patient (6 %) and three of eight patients (37.5 %) with residual fragments post local chemolysis, developed new stones during follow-up. The often neglected percutaneous chemolysis represents a significant and effective.

Percutaneous nephrostomy for symptomatic hypermobile kidney: a single centre experience.

PubMed

Starownik, Radosław; Golabek, Tomasz; Bar, Krzysztof; Muc, Kamil; Płaza, Paweł; Chlosta, Piotr

2014-12-01

Symptomatic hypermobile kidney is treated with nephropexy, a surgical procedure through which the floating kidney is fixed to the retroperitoneum. Although both open and endoscopic procedures have a high success rate, they can be associated with risk of complications, relatively long hospital stay and high cost. We describe our percutaneous technique for fixing a hypermobile kidney and evaluate the efficacy of the percutaneous nephrostomy insertion in management of symptomatic nephroptosis. Between January 2005 and December 2011, 11 patients diagnosed with a symptomatic right nephroptosis of at least 1 year duration were treated with a single point percutaneous nephrostomy technique. All data were retrieved from patients' medical records and then retrospectively analysed. Nephropexy through a single point percutaneous nephrostomy technique was successfully accomplished in 11 women. The mean operative time was 20 min. The intraoperative estimated blood loss was minimal in all cases. No major or minor intraoperative complications were noted. The average postoperative hospital stay was 2 days. Women returned to their usual activities 14 days following the surgery. Nine women had complete resolution of their pain, and 2 patients continued to complain of discomfort in their lumbar area. One patient was re-operated upon with satisfactory subjective and objective outcomes achieved. One patient refused re-operation. Percutaneous nephropexy is simple, inexpensive and effective for treatment of symptomatic hypermobile kidney. It remains a valuable alternative to open, laparoscopic, and robotic methods for fixing a floating kidney.

Patent Ductus Arteriosus closure in preterms less than 2kg: Surgery versus transcatheter.

PubMed

Pamukcu, Ozge; Tuncay, Aydin; Narin, Nazmi; Baykan, Ali; Korkmaz, Levent; Argun, Mustafa; Ozyurt, Abdullah; Sunkak, Suleyman; Uzum, Kazim

2018-01-01

As new devices come into the market, percutaneous techniques improve and interventionalists become more experienced; percutaneous closure gets more common in preterms. In this study we aimed to compare efficacy and safety of Patent Ductus Arteriosus closure surgically versus transcatheter method in preterms <2kg. Best of our knowledge this study is the first one that compares outcomes of surgery and percutaneous Patent Ductus Arteriosus closure in preterms. Between the dates July 1997 to October 2014 in our center Patent Ductus Arteriosus of 26 patients <2kg were closed percutaneously (Group A) and 31 less than 2kg operated (Group B). Weight of patients in percutaneous Patent Ductus Arteriosus closure group was significantly more than the surgery group. Mean gestational age of the patients in Group A was 30±1.8weeks, in group B was 28.6±3.5weeks. In group A; all cases were closed successfully except 4 cases: device embolization in 2, cardiac tamponade and iatrogenic aortic coarctation were seen. Pneumomediastinum and chylothorax were the major complications of the surgery group. There was no statistically significance between complication and success rates between two groups. Percutaneous Patent Ductus Arteriosus closure is the candidate for taking the place of surgery in preterms. However, it is not applied routinely; can only be done in fully equipped large centers by experienced interventionalists. Copyright © 2017 Elsevier B.V. All rights reserved.

Percutaneous endoscopic colostomy of the left colon: a new technique for management of intractable constipation in children.

PubMed

Rawat, David J; Haddad, Munther; Geoghegan, Niamh; Clarke, Simon; Fell, John M

2004-07-01

The antegrade colonic enema is accepted as effective for management of intractable constipation in children when conventional bowel management has failed. This study describes experience with a new, minimally invasive technique, the distal antegrade colonic enema, which involves percutaneous endoscopic colostomy of the left colon. Fifteen children with refractory constipation and soiling who had radiographic evidence of megarectum and/or distal colonic delay were selected for the procedure. The junction of the descending and the sigmoid colon was identified colonoscopically, and the percutaneous endoscopic colostomy tube, through which antegrade distal colonic enema are administered, was inserted. Fourteen children underwent distal percutaneous endoscopic colostomy insertion. The median time required for the procedure was 30 minutes (20-50 minutes). Excluding one child (technical difficulties with percutaneous endoscopic colostomy placement), median post-procedural hospital stay was 4 days (2-27 days). Thirteen children were no longer soiling, and improvement in quality of life was reported at 2 months' follow-up. At 6 months' follow-up, 90% of children were clean during intervals between enemas. All children evaluated at 12 months' follow-up remained clean. Median duration of follow-up was 12.5 months (2-51 months). The distal percutaneous endoscopic colostomy is a simple alternative to established methods for delivery of antegrade enemas. It is less invasive and on reversal leaves only minor scarring.

The effects of core stabilization exercise on dynamic balance and gait function in stroke patients.

PubMed

Chung, Eun-Jung; Kim, Jung-Hee; Lee, Byoung-Hee

2013-07-01

[Purpose] The purpose of this study was to determine the effects of core stabilization exercise on dynamic balance and gait function in stroke patients. [Subjects] The subjects were 16 stroke patients, who were randomly divided into two groups: a core stabilization exercise group of eight subjects and control group of eight subjects. [Methods] Subjects in both groups received general training five times per week. Subjects in the core stabilization exercise group practiced an additional core stabilization exercise program, which was performed for 30 minutes, three times per week, during a period of four weeks. All subjects were evaluated for dynamic balance (Timed Up and Go test, TUG) and gait parameters (velocity, cadence, step length, and stride length). [Results] Following intervention, the core exercise group showed a significant change in TUG, velocity, and cadence. The only significant difference observed between the core group and control group was in velocity. [Conclusion] The results of this study suggest the feasibility and suitability of core stabilization exercise for stroke patients.

The roles of amensalistic and commensalistic interactions in large ecological network stability

PubMed Central

Mougi, Akihiko

2016-01-01

Ecological communities comprise diverse species and their interactions. Notably, ecological and evolutionary studies have revealed that reciprocal interactions such as predator–prey, competition, and mutualism, are key drivers of community dynamics. However, there is an argument that many species interactions are asymmetric, where one species unilaterally affects another species (amensalism or commensalism). This raises the unanswered question of what is the role of unilateral interactions in community dynamics. Here I use a theoretical approach to demonstrate that unilateral interactions greatly enhance community stability. The results suggested that amensalism and commensalism were more stabilizing than symmetrical interactions, such as competition and mutualism, but they were less stabilizing than an asymmetric antagonistic interaction. A mix of unilateral interactions increased stability. Furthermore, in communities with all interaction types, unilateral interactions tended to increase stability. This study suggests that unilateral interactions play a major role in maintaining communities, underlining the need to further investigate their roles in ecosystem dynamics. PMID:27406267

Why have hydrostatic bearings been avoided as a stabilizing element for rotating machines

NASA Technical Reports Server (NTRS)

Bently, D. E.; Muszynska, A.

1985-01-01

The advantages are discussed of hydrostatic, high pressure bearings as providers of higher margin of stability to the rotor/bearing systems. It is apparent that deliberate use of hydrostatic bearing high pressure lubricated (any gas or liquid) can easily be used to build higher stability margin into rotating machinery, in spite of the thirty years bias against high pressure lubrication. Since this supply pressure is controllable (the Direct Dynamic Stiffness at lower eccentricity is also controllable) so that within some rotor system limits, the stability margin and dynamic response of the rotor system is more readily controllable. It may be possible to take advantage of this effect in the various seals, as well as the bearings, to assist with stability margin and dynamic response of rotating machinery. The stability of the bearing can be additionally improved by taking advantage of the anti-swirling concept. The high pressure fluid supply inlets should be located tangentially at the bearing circumference and directed against rotation. The incoming fluid flow creates stability by reducing the swirling rate.

In-plane stability analysis of non-uniform cross-sectioned curved beams

NASA Astrophysics Data System (ADS)

Öztürk, Hasan; Yeşilyurt, İsa; Sabuncu, Mustafa

2006-09-01

In this study, in-plane stability analysis of non-uniform cross-sectioned thin curved beams under uniformly distributed dynamic loads is investigated by using the Finite Element Method. The first and second unstable regions are examined for dynamic stability. In-plane vibration and in-plane buckling are also studied. Two different finite element models, representing variations of cross-section, are developed by using simple strain functions in the analysis. The results obtained from this study are compared with the results of other investigators in existing literature for the fundamental natural frequency and critical buckling load. The effects of opening angle, variations of cross-section, static and dynamic load parameters on the stability regions are shown in graphics.

Vision-based stabilization of nonholonomic mobile robots by integrating sliding-mode control and adaptive approach

NASA Astrophysics Data System (ADS)

Cao, Zhengcai; Yin, Longjie; Fu, Yili

2013-01-01

Vision-based pose stabilization of nonholonomic mobile robots has received extensive attention. At present, most of the solutions of the problem do not take the robot dynamics into account in the controller design, so that these controllers are difficult to realize satisfactory control in practical application. Besides, many of the approaches suffer from the initial speed and torque jump which are not practical in the real world. Considering the kinematics and dynamics, a two-stage visual controller for solving the stabilization problem of a mobile robot is presented, applying the integration of adaptive control, sliding-mode control, and neural dynamics. In the first stage, an adaptive kinematic stabilization controller utilized to generate the command of velocity is developed based on Lyapunov theory. In the second stage, adopting the sliding-mode control approach, a dynamic controller with a variable speed function used to reduce the chattering is designed, which is utilized to generate the command of torque to make the actual velocity of the mobile robot asymptotically reach the desired velocity. Furthermore, to handle the speed and torque jump problems, the neural dynamics model is integrated into the above mentioned controllers. The stability of the proposed control system is analyzed by using Lyapunov theory. Finally, the simulation of the control law is implemented in perturbed case, and the results show that the control scheme can solve the stabilization problem effectively. The proposed control law can solve the speed and torque jump problems, overcome external disturbances, and provide a new solution for the vision-based stabilization of the mobile robot.

Dynamic stability control in forward falls: postural corrections after muscle fatigue in young and older adults.

PubMed

Mademli, Lida; Arampatzis, Adamantios; Karamanidis, Kiros

2008-06-01

Many studies report that muscle strength loss may alter the human system's capacity to generate rapid force for balance corrections after perturbations, leading to deficient recovery behaviours. Yet little is known regarding the effect of modifications in the neuromuscular system induced by fatigue on dynamic stability control during postural perturbations. This study investigates the effect of muscle strength decline induced by fatiguing contractions on the dynamic stability control of young and older adults during forward falls. Eleven young and eleven older male adults had to regain balance after sudden falls before and after submaximal fatiguing knee extension-flexion contractions. Young subjects had a higher margin of stability than older ones before and after the fatiguing task. This reflects their enhanced ability in using mechanisms for maintaining dynamic stability (i.e. a greater base of support). The margin of stability, the boundary of the base of support and the position of the extrapolated centre of mass, remained unaffected by the reduction in muscle strength induced by the fatiguing contractions, indicating an appropriate adjustment of the motor commands to compensate the deficit in muscle strength. Both young and older adults were able to counteract the decreased horizontal ground reaction forces after the fatiguing task by flexing their knee to a greater extent, leading to similar decreases in the horizontal velocity of centre of mass as in the pre fatigue condition. The results demonstrate the ability of the central nervous system to rapidly modify the execution of postural corrections including mechanisms for maintaining dynamic stability.

A direct comparison of spine rotational stiffness and dynamic spine stability during repetitive lifting tasks.

PubMed

Graham, Ryan B; Brown, Stephen H M

2012-06-01

Stability of the spinal column is critical to bear loads, allow movement, and at the same time avoid injury and pain. However, there has been a debate in recent years as to how best to define and quantify spine stability, with the outcome being that different methods are used without a clear understanding of how they relate to one another. Therefore, the goal of the present study was to directly compare lumbar spine rotational stiffness, calculated with an EMG-driven biomechanical model, to local dynamic spine stability calculated using Lyapunov analyses of kinematic data, during a series of continuous dynamic lifting challenges. Twelve healthy male subjects performed 30 repetitive lifts under three varying load and three varying rate conditions. With an increase in the load lifted (constant rate) there was a significant increase in mean, maximum, and minimum spine rotational stiffness (p<0.001) and a significant increase in local dynamic stability (p<0.05); both stability measures were moderately to strongly related to one another (r=-0.55 to -0.71). With an increase in lifting rate (constant load), there was also a significant increase in mean and maximum spine rotational stiffness (p<0.01); however, there was a non-significant decrease in the minimum rotational stiffness and a non-significant decrease in local dynamic stability (p>0.05). Weak linear relationships were found for the varying rate conditions (r=-0.02 to -0.27). The results suggest that spine rotational stiffness and local dynamic stability are closely related to one another, as they provided similar information when movement rate was controlled. However, based on the results from the changing lifting rate conditions, it is evident that both models provide unique information and that future research is required to completely understand the relationship between the two models. Using both techniques concurrently may provide the best information regarding the true effects of (in) stability under different loading and movement scenarios, and in comparing healthy and clinical populations. Copyright © 2012 Elsevier Ltd. All rights reserved.

Filopodial dynamics and growth cone stabilization in Drosophila visual circuit development

PubMed Central

Özel, Mehmet Neset; Langen, Marion; Hassan, Bassem A; Hiesinger, P Robin

2015-01-01

Filopodial dynamics are thought to control growth cone guidance, but the types and roles of growth cone dynamics underlying neural circuit assembly in a living brain are largely unknown. To address this issue, we have developed long-term, continuous, fast and high-resolution imaging of growth cone dynamics from axon growth to synapse formation in cultured Drosophila brains. Using R7 photoreceptor neurons as a model we show that >90% of the growth cone filopodia exhibit fast, stochastic dynamics that persist despite ongoing stepwise layer formation. Correspondingly, R7 growth cones stabilize early and change their final position by passive dislocation. N-Cadherin controls both fast filopodial dynamics and growth cone stabilization. Surprisingly, loss of N-Cadherin causes no primary targeting defects, but destabilizes R7 growth cones to jump between correct and incorrect layers. Hence, growth cone dynamics can influence wiring specificity without a direct role in target recognition and implement simple rules during circuit assembly. DOI: http://dx.doi.org/10.7554/eLife.10721.001 PMID:26512889

Incidence of Gastrointestinal Bleeding After Percutaneous Coronary Intervention: A Single Center Experience.

PubMed

Aziz, Fahad

2014-02-01

Gastrointestinal (GI) bleeding is a hemorrhagic complication after percutaneous coronary intervention in patients with acute myocardial infarction. The purpose of the study is to determine predictors of GI bleeding and impact of GI bleeding on the patients undergoing percutaneous coronary intervention. GI bleeding occurred in 6 (7.1%) of 84 patients with STEMI/NSETMI (ST-segment elevated myocardial infarction/Non ST-segment elevated myocardial infarction) undergoing primary percutaneous coronary intervention. Univariate analysis demonstrates that patients with GI bleeding had a significantly higher previous GI bleeding (16.66% vs. 8.6%, P < 0.001). Higher Killip classification at presentation was associated with higher incidence of GI bleeding (61% vs. 18%, P < 0.01). The use of proton pump inhibitors did not reduce the risk of GI bleeding. The GI bleeding in these patients was associated with higher mortality and morbidity in the post percutaneous coronary intervention period. Although, GI bleeding in patients with MI significantly increases mortality and morbidity, previous GI bleeding and higher Killip class are associated with higher incidence of GI bleeding. High-risk patients for GI bleeding can be identified at presentation.

Closed percutaneous pleural biopsy. A lost art in the new era.

PubMed

Khadadah, Mousa E; Muqim, Abdulaziz T; Al-Mutairi, Abdulla D; Nahar, Ibrahim K; Sharma, Prem N; Behbehani, Nasser H; El-Maradni, Nabeel M

2009-06-01

To assess the association between size and number of biopsy specimens obtained by percutaneous closed pleural biopsy, with overall diagnostic yield in general, and histopathological evidence of tuberculosis pleurisy, in particular. One hundred and forty-three patients, with a high index of clinically having tuberculous pleurisy, were referred to the respiratory division of Mubarak Al-Kabeer Hospital in Kuwait during a 9-year period (January 1999 to December 2007). All subjects with exudative lymphocytic predominant effusion underwent percutaneous closed pleural biopsy, looking for tuberculous granulomas. The clinical diagnosis and pathological characteristics (number and size of biopsy samples) were analyzed. Overall diagnostic yield of percutaneous closed pleural biopsy in all cases was noticed to be 52%. The larger biopsy sample size of 3 mm and more, and the higher number of specimens (> or = 4) were significantly associated with an increased diagnostic yield for tuberculous pleurisy (p=0.007 and 0.047). Obtaining 4 or more biopsy samples, and larger specimens of 3mm and more for histopathological evaluation, through percutaneous pleural biopsy, results in a better diagnostic yield for tuberculous pleurisy.

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

Harding, James, E-mail: drjames.harding@btinternet.com; Mortimer, Alex; Kelly, Michael

Percutaneous cholecystostomy is a minimally invasive procedure for providing gallbladder decompression, often in critically ill patients. It can be used in malignant biliary obstruction following failed endoscopic retrograde cholangiopancreatography when the intrahepatic ducts are not dilated or when stent insertion is not possible via the bile ducts. In properly selected patients, percutaneous cholecystostomy in obstructive jaundice is a simple, safe, and rapid option for biliary decompression, thus avoiding the morbidity and mortality involved with percutaneous transhepatic biliary stenting. Subsequent use of a percutaneous cholecystostomy for definitive biliary stent placement is an attractive concept and leaves patients with no external drain.more » To the best of our knowledge, it has only been described on three previous occasions in the published literature, on each occasion forced by surgical or technical considerations. Traditionally, anatomic/technical considerations and the risk of bile leak have precluded such an approach, but improvements in catheter design and manufacture may now make it more feasible. We report a case of successful interval metal stent placement via percutaneous cholecystostomy which was preplanned and achieved excellent palliation for the patient. The pros and cons of the procedure and approach are discussed.« less

Robotics in percutaneous cardiovascular interventions.

PubMed

Pourdjabbar, Ali; Ang, Lawrence; Behnamfar, Omid; Patel, Mitul P; Reeves, Ryan R; Campbell, Paul T; Madder, Ryan D; Mahmud, Ehtisham

2017-11-01

The fundamental technique of performing percutaneous cardiovascular (CV) interventions has remained unchanged and requires operators to wear heavy lead aprons to minimize exposure to ionizing radiation. Robotic technology is now being utilized in interventional cardiology partially as a direct result of the increasing appreciation of the long-term occupational hazards of the field. This review was undertaken to report the clinical outcomes of percutaneous robotic coronary and peripheral vascular interventions. Areas covered: A systematic literature review of percutaneous robotic CV interventions was undertaken. The safety and feasibility of percutaneous robotically-assisted CV interventions has been validated in simple to complex coronary disease, and iliofemoral disease. Studies have shown that robotically-assisted PCI significantly reduces operator exposure to harmful ionizing radiation without compromising procedural success or clinical efficacy. In addition to the operator benefits, robotically-assisted intervention has the potential for patient advantages by allowing more accurate lesion length measurement, precise stent placement and lower patient radiation exposure. However, further investigation is required to fully elucidate these potential benefits. Expert commentary: Incremental improvement in robotic technology and telecommunications would enable treatment of an even broader patient population, and potentially provide remote robotic PCI.

Percutaneous full endoscopic lumbar foraminoplasty for adjacent level foraminal stenosis following vertebral intersegmental fusion in an awake and aware patient under local anesthesia: A case report.

PubMed

Yamashita, Kazuta; Higashino, Kosaku; Sakai, Toshinori; Takata, Yoichiro; Hayashi, Fumio; Tezuka, Fumitake; Morimoto, Masatoshi; Chikawa, Takashi; Nagamachi, Akihiro; Sairyo, Koichi

2017-01-01

Percutaneous endoscopic surgery for the lumbar spine has become established in the last decade. It requires only an 8 mm skin incision, causes minimal damage to the paravertebral muscles, and can be performed under local anesthesia. With the advent of improved equipment, in particular the high-speed surgical drill, the indications for percutaneous endoscopic surgery have expanded to include lumbar spinal canal stenosis. Transforaminal percutaneous endoscopic discectomy has been used to treat intervertebral stenosis. However, it has been reported that adjacent level disc degeneration and foraminal stenosis can occur following intervertebral segmental fusion. When this adjacent level pathology becomes symptomatic, additional fusion surgery is often needed. We performed minimally invasive percutaneous full endoscopic lumbar foraminoplasty in an awake and aware 50-year-old woman under local anesthesia. The procedure was successful with no complications. Her radiculopathy, including muscle weakness and leg pain due to impingement of the exiting nerve, improved after the surgery. J. Med. Invest. 64: 291-295, August, 2017.

Summary of methods for calculating dynamic lateral stability and response and for estimating aerodynamic stability derivatives

NASA Technical Reports Server (NTRS)

Campbell, John P; Mckinney, Marion O

1952-01-01

A summary of methods for making dynamic lateral stability and response calculations and for estimating the aerodynamic stability derivatives required for use in these calculations is presented. The processes of performing calculations of the time histories of lateral motions, of the period and damping of these motions, and of the lateral stability boundaries are presented as a series of simple straightforward steps. Existing methods for estimating the stability derivatives are summarized and, in some cases, simple new empirical formulas are presented. Detailed estimation methods are presented for low-subsonic-speed conditions but only a brief discussion and a list of references are given for transonic and supersonic speed conditions.

An Investigation of the Elements which Contribute to Statical and Dynamical Stability, and of the Effects of Variation in Those Elements

NASA Technical Reports Server (NTRS)

Klemin, Alexander; Warner, Edward P; Denkinger, George M

1918-01-01

Part 1 gives details of models tested and methods of testing of the Eiffel 36 wing alone and the JN2 aircraft. Characteristics and performance curves for standard JN are included. Part 2 presents a statistical analysis of the following: lift and drag contributed by body and chassis tested without wings; lift and drag contributed by tail, tested without wings; the effect on lift and drift of interference between the wings of a biplane combination; lift and drag contributed by the addition of body, chassis, and tail to a biplane combination; total parasite resistance; effect of varying size of tail, keeping angle of setting constant; effect of varying length of body and size of tail at the same time, keeping constant moment of tail surface about the center of gravity; forces on the tail and the effects of downwash; effect of size and setting of tail on statical longitudinal stability effects of length of body on stability; the effects of the various elements of an airplane on longitudinal stability and the placing of the force vectors. Part 3 presents the fundamental principals of dynamical stability; computations of resistance derivatives; solution of the stability equation; dynamical stability of the Curtiss JN2; tabulation of resistance derivatives; discussion of the resistance derivatives; formation and solution of stability equations; physical conceptions of the resistance derivatives; elements contributing to damping and an investigation of low speed conditions. Part 4 includes a summary of the results of the statistical investigation and a summary of the results for dynamic stability.

Applying Aerodynamics Inspired Organizational Dynamic Fit Model Disaster Relief Endeavors

DTIC Science & Technology

2010-12-01

gusts, and a dynamically stable organization returns quickly to its intended profit level, for instance, after deviation by changed consumer preferences . Hence...dynamic stability limits the level, for instance, by changed consumer preferences . Hence static stability limits initial performance... consumer preferences Maneuverability Quickness of a controlled system’s planned change from one trajectory to another Quickness of planned

Nonlinear Slewing Spacecraft Control Based on Exergy, Power Flow, and Static and Dynamic Stability

NASA Astrophysics Data System (ADS)

Robinett, Rush D.; Wilson, David G.

2009-10-01

This paper presents a new nonlinear control methodology for slewing spacecraft, which provides both necessary and sufficient conditions for stability by identifying the stability boundaries, rigid body modes, and limit cycles. Conservative Hamiltonian system concepts, which are equivalent to static stability of airplanes, are used to find and deal with the static stability boundaries: rigid body modes. The application of exergy and entropy thermodynamic concepts to the work-rate principle provides a natural partitioning through the second law of thermodynamics of power flows into exergy generator, dissipator, and storage for Hamiltonian systems that is employed to find the dynamic stability boundaries: limit cycles. This partitioning process enables the control system designer to directly evaluate and enhance the stability and performance of the system by balancing the power flowing into versus the power dissipated within the system subject to the Hamiltonian surface (power storage). Relationships are developed between exergy, power flow, static and dynamic stability, and Lyapunov analysis. The methodology is demonstrated with two illustrative examples: (1) a nonlinear oscillator with sinusoidal damping and (2) a multi-input-multi-output three-axis slewing spacecraft that employs proportional-integral-derivative tracking control with numerical simulation results.

Stability analysis of dynamic collaboration model with control signals on two lanes

NASA Astrophysics Data System (ADS)

Li, Zhipeng; Zhang, Run; Xu, Shangzhi; Qian, Yeqing; Xu, Juan

2014-12-01

In this paper, the influence of control signals on the stability of two-lane traffic flow is mainly studied by applying control theory with lane changing behaviors. We present the two-lane dynamic collaboration model with lateral friction and the expressions of feedback control signals. What is more, utilizing the delayed feedback control theory to the two-lane dynamic collaboration model with control signals, we investigate the stability of traffic flow theoretically and the stability conditions for both lanes are derived with finding that the forward and lateral feedback signals can improve the stability of traffic flow while the backward feedback signals cannot achieve it. Besides, direct simulations are conducted to verify the results of theoretical analysis, which shows that the feedback signals have a significant effect on the running state of two vehicle groups, and the results are same with the theoretical analysis.

Troponin test

MedlinePlus

... Bates ER, Blankenship JC, et al. 2015 ACC/AHA/SCAI Focused update on primary percutaneous coronary intervention ... myocardial infarction: an update of the 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention and the ...

Percutaneous Tracheostomy and Percutaneous Angiography: The Diuturnity of Sven-Ivar Seldinger of Mora, Pasquale Ciaglia of Utica

PubMed Central

Pollock, Richard A.

2016-01-01

In the latter part of the 20th century, three developments intersected: skin-to-artery catheterization, percutaneous tracheostomy, and market introduction of video-chip camera-tipped endoscopes. By the millennium, every vessel within the body could be visualized radiographically, and percutaneous tracheostomy (with tracheal-ring “dilation,” flawless high-resolution intratracheal video-imagery, and tracheal intubation) could consistently be achieved at the patient's bedside. Initiated through the skin and abetted by guide-wire insertion, these procedures are the lasting gifts of Sven-Ivar Seldinger (1921–1998) of Mora, Sweden, and Pasquale Ciaglia (1912–2000) of Utica, New York. Physicians and surgeons managing intracranial, craniofacial, and maxillofacial injury are among those honoring the Seldinger–Ciaglia “collaboration.” PMID:27833711

Limit Cycle Analysis Applied to the Oscillations of Decelerating Blunt-Body Entry Vehicles

NASA Technical Reports Server (NTRS)

Schoenenberger, Mark; Queen, Eric M.

2008-01-01

Many blunt-body entry vehicles have nonlinear dynamic stability characteristics that produce self-limiting oscillations in flight. Several different test techniques can be used to extract dynamic aerodynamic coefficients to predict this oscillatory behavior for planetary entry mission design and analysis. Most of these test techniques impose boundary conditions that alter the oscillatory behavior from that seen in flight. Three sets of test conditions, representing three commonly used test techniques, are presented to highlight these effects. Analytical solutions to the constant-coefficient planar equations-of-motion for each case are developed to show how the same blunt body behaves differently depending on the imposed test conditions. The energy equation is applied to further illustrate the governing dynamics. Then, the mean value theorem is applied to the energy rate equation to find the effective damping for an example blunt body with nonlinear, self-limiting dynamic characteristics. This approach is used to predict constant-energy oscillatory behavior and the equilibrium oscillation amplitudes for the various test conditions. These predictions are verified with planar simulations. The analysis presented provides an overview of dynamic stability test techniques and illustrates the effects of dynamic stability, static aerodynamics and test conditions on observed dynamic motions. It is proposed that these effects may be leveraged to develop new test techniques and refine test matrices in future tests to better define the nonlinear functional forms of blunt body dynamic stability curves.

Dynamical entropy via entropy of non-random matrices: application to stability and complexity in modelling ecosystems.

PubMed

Chakrabarti, C G; Ghosh, Koyel

2013-10-01

In the present paper we have first introduced a measure of dynamical entropy of an ecosystem on the basis of the dynamical model of the system. The dynamical entropy which depends on the eigenvalues of the community matrix of the system leads to a consistent measure of complexity of the ecosystem to characterize the dynamical behaviours such as the stability, instability and periodicity around the stationary states of the system. We have illustrated the theory with some model ecosystems. Copyright © 2013 Elsevier Inc. All rights reserved.

Study of Anti-Vortex Baffle Effect in Suppressing Swirling Flow in LOX Tank

NASA Technical Reports Server (NTRS)

Yang, H. Q.; Peugeot, John

2011-01-01

Experimental results describing the hydraulic dynamic pump transfer matrix (Yp) for a cavitating J-2X oxidizer turbopump inducer+impeller tested in subscale waterflow are presented. The transfer function is required for integrated vehicle pogo stability analysis as well as optimization of local inducer pumping stability. Dynamic transfer functions across widely varying pump hydrodynamic inlet conditions are extracted from measured data in conjunction with 1D-model based corrections. Derived Dynamic transfer functions are initially interpreted relative to traditional Pogo pump equations. Water-to-liquid oxygen scaling of measured cavitation characteristics are discussed. Comparison of key dynamic transfer matrix terms derived from waterflow testing are made with those implemented in preliminary Ares Upper Stage Pogo stability modeling. Alternate cavitating pump hydraulic dynamic equations are suggested which better reflect frequency dependencies of measured transfer matrices.

U32: vehicle stability and dynamics longer combination vehicles final report.

DOT National Transportation Integrated Search

2011-09-01

This study investigated the safety and stability of longer combination vehicles (LCVs), in particular a triple trailer combination behind a commercial tractor, which has more complicated dynamics than the more common tractor in combination with a sin...

Flight Investigation to Improve the Dynamic Longitudinal Stability and Control-Feel Characteristics of the P-63A-1 Airplane (AAF No. 42-68889) with Closely Balanced Experimental Elevators

NASA Technical Reports Server (NTRS)

Johnson, Harold I.

1946-01-01

Results of flight tests of a control-feel aid presented. This device consisted of a spring and dashpot connected in series between the control stick and airplane structure. The device was tested in combination with an experimental elevator and bobweight which had given unsatisfactory dynamic stability and control-feel characteristics in previous tests. The control-feel aid effected marked improvement in both the control-feel characteristics and the control-feel dynamic longitudinal stability of the airplane.

Dynamic stability of maglev systems

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

Cai, Y.; Chen, S.S.; Mulcahy, T.M.

1992-09-01

Since the occurrence of dynamic instabilities is not acceptable for any commercial maglev systems, it is important to consider the dynamic instability in the development of all maglev systems. This study is to consider the stability of maglev systems based on experimental data, scoping calculations and simple mathematical models. Divergence and flutter are obtained for coupled vibration of a three-degree-of-freedom maglev vehicle on the guideway which consists of double L-shaped aluminum segments attached to a rotating wheel. The theory and analysis developed in this study provides basic stability characteristics and identifies future research needs for maglev system.

The influence of dynamic inflow and torsional flexibility on rotor damping in forward flight from symbolically generated equations

NASA Technical Reports Server (NTRS)

Reddy, T. S. R.; Warmbrodt, W.

1985-01-01

The combined effects of blade torsion and dynamic inflow on the aeroelastic stability of an elastic rotor blade in forward flight are studied. The governing sets of equations of motion (fully nonlinear, linearized, and multiblade equations) used in this study are derived symbolically using a program written in FORTRAN. Stability results are presented for different structural models with and without dynamic inflow. A combination of symbolic and numerical programs at the proper stage in the derivation process makes the obtainment of final stability results an efficient and straightforward procedure.

Guidelines for Computing Longitudinal Dynamic Stability Characteristics of a Subsonic Transport

NASA Technical Reports Server (NTRS)

Thompson, Joseph R.; Frank, Neal T.; Murphy, Patrick C.

2010-01-01

A systematic study is presented to guide the selection of a numerical solution strategy for URANS computation of a subsonic transport configuration undergoing simulated forced oscillation about its pitch axis. Forced oscillation is central to the prevalent wind tunnel methodology for quantifying aircraft dynamic stability derivatives from force and moment coefficients, which is the ultimate goal for the computational simulations. Extensive computations are performed that lead in key insights of the critical numerical parameters affecting solution convergence. A preliminary linear harmonic analysis is included to demonstrate the potential of extracting dynamic stability derivatives from computational solutions.

Dynamic trunk stabilization: a conceptual back injury prevention program for volleyball athletes.

PubMed

Smith, Chad E; Nyland, John; Caudill, Paul; Brosky, Joseph; Caborn, David N M

2008-11-01

The sport of volleyball creates considerable dynamic trunk stability demands. Back injury occurs all too frequently in volleyball, particularly among female athletes. The purpose of this clinical commentary is to review functional anatomy, muscle coactivation strategies, assessment of trunk muscle performance, and the characteristics of effective exercises for the trunk or core. From this information, a conceptual progressive 3-phase volleyball-specific training program is presented to improve dynamic trunk stability and to potentially reduce the incidence of back injury among volleyball athletes. Phase 1 addresses low-velocity motor control, kinesthetic awareness, and endurance, with the clinician providing cues to teach achievement of biomechanically neutral spine alignment. Phase 2 focuses on progressively higher velocity dynamic multiplanar endurance, coordination, and strength-power challenges integrating upper and lower extremity movements, while maintaining neutral spine alignment. Phase 3 integrates volleyball-specific skill simulations by breaking down composite movement patterns into their component parts, with differing dynamic trunk stability requirements, while maintaining neutral spine alignment. Prospective research is needed to validate the efficacy of this program.

Dynamical Stability and Evolution of Kepler’s compact inner multi-planet systems

NASA Astrophysics Data System (ADS)

Pu, Bonan

2017-06-01

NASA’s Kepler mission has revealed a population of highly compact inner multi-planet systems. These systems, typically consisting of 4-6 super-Earths, feature tight orbital spacing between planets as well as low orbital inclinations (~2 deg. ) and eccentricities (~2%). This stands in contrast to Kepler’s singles population, which appears to feature higher orbital obliquities and eccentricities, as well as a lower transit timing variation fraction indicative of lower true planet multiplicities.In this talk, I will present some previous and ongoing research aimed at understanding the dynamical evolution of these Kepler systems. First, I will present numerical N-body investigations on the long-term stability of multi-planet systems, the results of which suggest that Kepler’s systems are near the edge of stability. Next, I will discuss some current research on the dynamics of planetary close encounters and collisions, and their implications for the ultimate fate of dynamically unstable multi-planet systems. Finally, I will highlight some recent results on the dynamical stability and evolution of inner multi-planet systems when they are accompanied by external giant planet and/or stellar companions.

Aqueous clay suspensions stabilized by alginate fluid gels for coal spontaneous combustion prevention and control.

PubMed

Qin, Botao; Ma, Dong; Li, Fanglei; Li, Yong

2017-11-01

We have developed aqueous clay suspensions stabilized by alginate fluid gels (AFG) for coal spontaneous combustion prevention and control. Specially, this study aimed to characterize the effect of AFG on the microstructure, static and dynamic stability, and coal fire inhibition performances of the prepared AFG-stabilized clay suspensions. Compared with aqueous clay suspensions, the AFG-stabilized clay suspensions manifest high static and dynamic stability, which can be ascribed to the formation of a robust three-dimensional gel network by AFG. The coal acceleration oxidation experimental results show that the prepared AFG-stabilized clay suspensions can improve the coal thermal stability and effectively inhibit the coal spontaneous oxidation process by increasing crossing point temperature (CPT) and reducing CO emission. The prepared low-cost and nontoxic AFG-stabilized clay suspensions, exhibiting excellent coal fire extinguishing performances, indicate great application potentials in coal spontaneous combustion prevention and control.

COMSAC: Computational Methods for Stability and Control. Part 1

NASA Technical Reports Server (NTRS)

Fremaux, C. Michael (Compiler); Hall, Robert M. (Compiler)

2004-01-01

Work on stability and control included the following reports:Introductory Remarks; Introduction to Computational Methods for Stability and Control (COMSAC); Stability & Control Challenges for COMSAC: a NASA Langley Perspective; Emerging CFD Capabilities and Outlook A NASA Langley Perspective; The Role for Computational Fluid Dynamics for Stability and Control:Is it Time?; Northrop Grumman Perspective on COMSAC; Boeing Integrated Defense Systems Perspective on COMSAC; Computational Methods in Stability and Control:WPAFB Perspective; Perspective: Raytheon Aircraft Company; A Greybeard's View of the State of Aerodynamic Prediction; Computational Methods for Stability and Control: A Perspective; Boeing TacAir Stability and Control Issues for Computational Fluid Dynamics; NAVAIR S&C Issues for CFD; An S&C Perspective on CFD; Issues, Challenges & Payoffs: A Boeing User s Perspective on CFD for S&C; and Stability and Control in Computational Simulations for Conceptual and Preliminary Design: the Past, Today, and Future?

Percutaneous Nephrostomy: Technical Aspects and Indications

PubMed Central

Dagli, Mandeep; Ramchandani, Parvati

2011-01-01

First described in 1955 by Goodwin et al as a minimally invasive treatment for urinary obstruction causing marked hydronephrosis, percutaneous nephrostomy (PCN) placement quickly found use in a wide variety of clinical indications in both dilated and nondilated systems. Although the advancement of modern endourological techniques has led to a decline in the indications for primary nephrostomy placement, PCNs still play an important role in the treatment of multiple urologic conditions. In this article, the indications, placement, and postprocedure management of percutaneous nephrostomy drainage are described. PMID:23204641

Percutaneous Cryotherapy of Vascular Malformation: Initial Experience

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

Cornelis, F., E-mail: francoiscornelis@hotmail.com; Neuville, A.; Labreze, C.

The present report describes a case of percutaneous cryotherapy in a 36-year-old woman with a large and painful pectoral venous malformation. Cryoablation was performed in a single session for this 9-cm mass with 24 h hospitalisation. At 2- and 6-month follow-up, the pain had completely disappeared, and magnetic resonance imaging demonstrated a significant decrease in size. Percutaneous cryoablation shows promise as a feasible and apparently safe method for local control in patients with symptomatic venous vascular malformations.

Dynamics differentiate between active and inactive inteins

PubMed Central

Cronin, Melissa; Coolbaugh, Michael J; Nellis, David; Zhu, Jianwei; Wood, David W.; Nussinov, Ruth; Ma, Buyong

2014-01-01

The balance between stability and dynamics for active enzymes can be somewhat quantified by studies of intein splicing and cleaving reactions. Inteins catalyze the ligation of flanking host exteins while excising themselves. The potential for applications led to engineering of a mini-intein splicing domain, where the homing endonuclease domain of the Mycobacterium tuberculosis RecA (Mtu recA) intein was removed. The remaining domains were linked by several short peptides, but splicing activity in all was substantially lower than the full-length intein. Native splicing activity was restored in some cases by a V67L mutation. Using computations and experiments, we examine the impact of this mutation on the stability and conformational dynamics of the mini-intein splicing domain. Molecular dynamics simulations were used to delineate the factors that determine the active state, including the V67L mini-intein mutant, and peptide linker. We found that (1) the V67L mutation lowers the global fluctuations in all modeled mini-inteins, stabilizing the mini-intein constructs; (2) the connecting linker length affects intein dynamics; and (3) the flexibilities of the linker and intein core are higher in the active structure. We have observed that the interaction of the linker region and a turn region around residues 35-41 provides the pathway for the allostery interaction. Our experiments reveal that intein catalysis is characterized by non-linear Arrhenius plot, confirming the significant contribution of protein conformational dynamics to intein function. We conclude that while the V67L mutation stabilizes the global structure, cooperative dynamics of all intein regions appear more important for intein function than high stability. Our studies suggest that effectively quenching the conformational dynamics of an intein through engineered allosteric interactions could deactivate intein splicing or cleaving. PMID:25087201

Effects of a cognitive dual task on variability and local dynamic stability in sustained repetitive arm movements using principal component analysis: a pilot study.

PubMed

Longo, Alessia; Federolf, Peter; Haid, Thomas; Meulenbroek, Ruud

2018-06-01

In many daily jobs, repetitive arm movements are performed for extended periods of time under continuous cognitive demands. Even highly monotonous tasks exhibit an inherent motor variability and subtle fluctuations in movement stability. Variability and stability are different aspects of system dynamics, whose magnitude may be further affected by a cognitive load. Thus, the aim of the study was to explore and compare the effects of a cognitive dual task on the variability and local dynamic stability in a repetitive bimanual task. Thirteen healthy volunteers performed the repetitive motor task with and without a concurrent cognitive task of counting aloud backwards in multiples of three. Upper-body 3D kinematics were collected and postural reconfigurations-the variability related to the volunteer's postural change-were determined through a principal component analysis-based procedure. Subsequently, the most salient component was selected for the analysis of (1) cycle-to-cycle spatial and temporal variability, and (2) local dynamic stability as reflected by the largest Lyapunov exponent. Finally, end-point variability was evaluated as a control measure. The dual cognitive task proved to increase the temporal variability and reduce the local dynamic stability, marginally decrease endpoint variability, and substantially lower the incidence of postural reconfigurations. Particularly, the latter effect is considered to be relevant for the prevention of work-related musculoskeletal disorders since reduced variability in sustained repetitive tasks might increase the risk of overuse injuries.

Gaze stability, dynamic balance and participation deficits in people with multiple sclerosis at fall-risk.

PubMed

Garg, Hina; Dibble, Leland E; Schubert, Michael C; Sibthorp, Jim; Foreman, K Bo; Gappmaier, Eduard

2018-05-05

Despite the common complaints of dizziness and demyelination of afferent or efferent pathways to and from the vestibular nuclei which may adversely affect the angular Vestibulo-Ocular Reflex (aVOR) and vestibulo-spinal function in persons with Multiple Sclerosis (PwMS), few studies have examined gaze and dynamic balance function in PwMS. 1) Determine the differences in gaze stability, dynamic balance and participation measures between PwMS and controls, 2) Examine the relationships between gaze stability, dynamic balance and participation. Nineteen ambulatory PwMS at fall-risk and 14 age-matched controls were recruited. Outcomes included (a) gaze stability [angular Vestibulo-Ocular Reflex (aVOR) gain (ratio of eye to head velocity); number of Compensatory Saccades (CS) per head rotation; CS latency; gaze position error; Coefficient of Variation (CV) of aVOR gain], (b) dynamic balance [Functional Gait Assessment, FGA; four square step test], and (c) participation [dizziness handicap inventory; activities-specific balance confidence scale]. Separate independent t-tests and Pearson's correlations were calculated. PwMS were age = 53 ± 11.7yrs and had 4.2 ± 3.3 falls/yr. PwMS demonstrated significant (p<0.05) impairments in gaze stability, dynamic balance and participation measures compared to controls. CV of aVOR gain and CS latency were significantly correlated with FGA. Deficits and correlations across a spectrum of disability measures highlight the relevance of gaze and dynamic balance assessment in PwMS. This article is protected by copyright. All rights reserved. © 2018 Wiley Periodicals, Inc.

Robotic percutaneous access to the kidney: comparison with standard manual access.

PubMed

Su, Li-Ming; Stoianovici, Dan; Jarrett, Thomas W; Patriciu, Alexandru; Roberts, William W; Cadeddu, Jeffrey A; Ramakumar, Sanjay; Solomon, Stephen B; Kavoussi, Louis R

2002-09-01

To evaluate the efficiency, accuracy, and safety of robotic percutaneous access to the kidney (PAKY) for percutaneous nephrolithotomy in comparison with conventional manual techniques. We compared the intraoperative access variables (number of access attempts, time to successful access, estimated blood loss, complications) of 23 patients who underwent robotic PAKY with the remote center of motion device (PAKY-RCM) with the same data from a contemporaneous series of 23 patients who underwent conventional manual percutaneous access to the kidney. The PAKY-RCM incorporates a robotic arm and a friction transmission with axial loading system to accurately position and insert a standard 18-gauge needle percutaneously into the kidney. The blood loss during percutaneous access was estimated on a four-point scale (1 = minimal to 4 = large). The color of effluent urine was graded on a four-point scale (1 = clear to 4 = red). The mean target calix width was 13.5 +/- 9.2 mm in the robotic group and 12.2 +/- 4.5 mm in the manual group (P = 0.57). When comparing PAKY-RCM with standard manual techniques, the mean number of attempts was 2.2 +/- 1.6 v 3.2 +/- 2.5 (P = 0.14), time to access was 10.4 +/- 6.5 minutes v 15.1 +/- 8.8 minutes (P = 0.06), estimated blood loss score was 1.3 +/- 0.49 v 1.7 +/- 0.66 (P = 0.14), and color of effluent urine following access was 2.0 +/- 0.90 v 2.1 +/- 0.7 (P = 0.82). The PAKY-RCM was successful in obtaining access in 87% (20 of 23) of cases. The other three patients (13%) required conversion to manual techniques. There were no major intraoperative complications in either group. Robotic PAKY is a feasible, safe, and efficacious method of obtaining renal access for nephrolithotomy. The number of attempts and time to access were comparable to those of standard manual percutaneous access techniques. These findings provide the groundwork for the development of a completely automated robot-assisted percutaneous renal access device.

Platelet counts on admission affect coronary flow, myocardial perfusion and left ventricular systolic function after primary percutaneous coronary intervention.

PubMed

Sharif, Dawod; Abu-Salem, Mira; Sharif-Rasslan, Amal; Rosenschein, Uri

2017-10-01

Patients with acute ST-elevation myocardial infarction (STEMI) and increased platelet count treated by fibrinolysis have worse outcomes. The aim of this study was to test the hypothesis that platelet blood count at admission in patients with acute STEMI treated by primary percutaneous coronary intervention affects coronary flow, myocardial perfusion and recovery of left ventricular systolic function. A total of 174 patients presenting with acute anterior STEMI and treated with primary percutaneous coronary intervention were included and divided into subgroups of admission platelet blood count of <200 K, 200-300 K, 300-400 K and >400 K. Evaluation of coronary artery flow and myocardial blush grade was performed according to the TIMI criteria. Electrocardiographic ST elevation resolution post-primary percutaneous coronary intervention was evaluated. Doppler echocardiographic evaluation of left anterior descending coronary artery velocities early and late after primary percutaneous coronary intervention and assessment of left ventricular ejection fraction and wall motion score index (WMSI) of left ventricular and left anterior descending coronary artery territory were performed. Post-primary percutaneous coronary intervention TIMI, myocardial blush grade and ST elevation resolution were similar in all groups. Patients with platelet counts <200 K had higher peak diastolic left anterior descending coronary artery velocity both early and late after primary percutaneous coronary intervention, and higher prevalence of left anterior descending coronary artery velocity deceleration time exceeding 600 ms, (45.5% vs. 40%, P<0.05). Patients with platelet counts >400 K presented with worse left ventricular ejection fraction, left ventricular WMSI and left anterior descending coronary artery WMSI, and before discharge this subgroup had worse left ventricular WMSI and left anterior descending coronary artery WMSI, P<0.01. Patients with anterior STEMI treated by primary percutaneous coronary intervention with lower admission platelet count had higher left anterior descending coronary artery diastolic velocities, better myocardial perfusion with more patients having left anterior descending coronary artery-descending coronary artery velocity deceleration time >600 ms. Patients with higher platelet counts had lower left ventricular systolic function both at admission and before discharge.

Ultrasound-Guided Application of Percutaneous Electrolysis as an Adjunct to Exercise and Manual Therapy for Subacromial Pain Syndrome: a Randomized Clinical Trial.

PubMed

de-Miguel-Valtierra, Lorena; Salom-Moreno, Jaime; Fernández-de-Las-Peñas, César; Cleland, Joshua A; Arias-Buría, José L

2018-05-16

This randomized clinical trial compared the effects of adding US-guided percutaneous electrolysis into a program consisting of manual therapy and exercise on pain, related-disability, function and pressure sensitivity in subacromial pain syndrome. Fifty patients with subacromial pain syndrome were randomized into manual therapy and exercise or percutaneous electrolysis group. All patients received the same manual therapy and exercise program, one session per week for 5 consecutive weeks. Patients assigned to the electrolysis group also received the application of percutaneous electrolysis at each session. The primary outcome was Disabilities of the Arm, Shoulder and Hand (DASH). Secondary outcomes included pain, function (Shoulder Pain and Disability Index-SPADI) pressure pain thresholds (PPTs) and Global Rating of Change (GROC). They were assessed at baseline, post-treatment, and 3, and 6 months after treatment. Both groups showed similar improvements in the primary outcome (DASH) at all follow-ups (P=0.051). Subjects receiving manual therapy, exercise, and percutaneous electrolysis showed significantly greater changes in shoulder pain (P<0.001) and SPADI (P<0.001) than those receiving manual therapy and exercise alone at all follow-ups. Effect sizes were large (SMD>0.91) for shoulder pain and function at 3 and 6 months in favour of the percutaneous electrolysis group. No between-groups differences in PPT were found. The current clinical trial found that the inclusion of US-guided percutaneous electrolysis in combination with manual therapy and exercise resulted in no significant differences for related-disability (DASH) than the application of manual therapy and exercise alone in patients with subacromial pain syndrome. Nevertheless, differences were reported for some secondary outcomes such as shoulder pain and function (SPADI). Whether or not these effects are reliable should be addressed in future studies Perspective This study found that the inclusion of US-guided percutaneous electrolysis into a manual therapy and exercise program resulted in no significant differences for disability and pressure pain sensitivity than the application of manual therapy and exercise alone in patients with subacromial pain syndrome. Copyright © 2018. Published by Elsevier Inc.

Dynamics of a gravity-gradient stabilized flexible spacecraft

NASA Technical Reports Server (NTRS)

Meirovitch, L.; Juang, J. N.

1974-01-01

The dynamics of gravity-gradient stabilized flexible satellite in the neighborhood of a deformed equilibrium configuration are discussed. First the equilibrium configuration was determined by solving a set of nonlinear differential equations. Then stability of motion about the deformed equilibrium was tested by means of the Liapunov direct method. The natural frequencies of oscillation of the complete structure were calculated. The analysis is applicable to the RAE/B satellite.

A heterogenous Cournot duopoly with delay dynamics: Hopf bifurcations and stability switching curves

NASA Astrophysics Data System (ADS)

Pecora, Nicolò; Sodini, Mauro

2018-05-01

This article considers a Cournot duopoly model in a continuous-time framework and analyze its dynamic behavior when the competitors are heterogeneous in determining their output decision. Specifically the model is expressed in the form of differential equations with discrete delays. The stability conditions of the unique Nash equilibrium of the system are determined and the emergence of Hopf bifurcations is shown. Applying some recent mathematical techniques (stability switching curves) and performing numerical simulations, the paper confirms how different time delays affect the stability of the economy.

Dynamic stability of a helicopter with hinged rotor blades

NASA Technical Reports Server (NTRS)

Hohenemser, K

1939-01-01

The present report is a study of the dynamic stability of a helicopter with hinged rotor blades under hovering conditions. While in this case perfect stability can in general not be obtained it is possible by means of design features to prolong the period of the spontaneous oscillations of the helicopter and reduce their amplification, and so approximately assure neutral equilibrium. The possibility of controlled stability of a helicopter fitted with hinged blades is proved by the successful flights of various helicopters, particularly of the Focker FW61 helicopter.

A class of stabilizing controllers for flexible multibody systems

NASA Technical Reports Server (NTRS)

Joshi, Suresh M.; Kelkar, Atul G.; Maghami, Peiman G.

1995-01-01

The problem of controlling a class of nonlinear multibody flexible space systems consisting of a flexible central body to which a number of articulated appendages are attached is considered. Collocated actuators and sensors are assumed, and global asymptotic stability of such systems is established under a nonlinear dissipative control law. The stability is shown to be robust to unmodeled dynamics and parametric uncertainties. For a special case in which the attitude motion of the central body is small, the system, although still nonlinear, is shown to be stabilized by linear dissipative control laws. Two types of linear controllers are considered: static dissipative (constant gain) and dynamic dissipative. The static dissipative control law is also shown to provide robust stability in the presence of certain classes of actuator and sensor nonlinearities and actuator dynamics. The results obtained for this special case can also be readily applied for controlling single-body linear flexible space structures. For this case, a synthesis technique for the design of a suboptimal dynamic dissipative controller is also presented. The results obtained in this paper are applicable to a broad class of multibody and single-body systems such as flexible multilink manipulators, multipayload space platforms, and space antennas. The stability proofs use the Lyapunov approach and exploit the inherent passivity of such systems.

Rotation in vibration, optimization, and aeroelastic stability problems. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Kaza, K. R. V.

1974-01-01

The effects of rotation in the areas of vibrations, dynamic stability, optimization, and aeroelasticity were studied. The governing equations of motion for the study of vibration and dynamic stability of a rapidly rotating deformable body were developed starting from the nonlinear theory of elasticity. Some common features such as the limitations of the classical theory of elasticity, the choice of axis system, the property of self-adjointness, the phenomenon of frequency splitting, shortcomings of stability methods as applied to gyroscopic systems, and the effect of internal and external damping on stability in gyroscopic systems are identified and discussed, and are then applied to three specific problems.

Fixed-time stabilization of impulsive Cohen-Grossberg BAM neural networks.

PubMed

Li, Hongfei; Li, Chuandong; Huang, Tingwen; Zhang, Wanli

2018-02-01

This article is concerned with the fixed-time stabilization for impulsive Cohen-Grossberg BAM neural networks via two different controllers. By using a novel constructive approach based on some comparison techniques for differential inequalities, an improvement theorem of fixed-time stability for impulsive dynamical systems is established. In addition, based on the fixed-time stability theorem of impulsive dynamical systems, two different control protocols are designed to ensure the fixed-time stabilization of impulsive Cohen-Grossberg BAM neural networks, which include and extend the earlier works. Finally, two simulations examples are provided to illustrate the validity of the proposed theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.

BELOWGROUND NITROGEN UPTAKE AND ALLOCATION BY SPARTINA ALTERNIFLORA AND DISTICHLIS SPICATA

EPA Science Inventory

Anthropogenic nitrogen inputs coupled with rising sea level complicate predictions of marsh stability. As marsh stability is a function of its vegetation, it is important to understand the mechanisms that drive community dynamics. Many studies have examined aboveground dynamics a...

DYNAMIC LANDSCAPES, STABILITY AND ECOLOGICAL MODELING

EPA Science Inventory

The image of a ball rolling along a series of hills and valleys is an effective heuristic by which to communicate stability concepts in ecology. However, the dynamics of this landscape model have little to do with ecological systems. Other landscape representations, however, are ...

Percutaneous cardiopulmonary support for catheter ablation of unstable ventricular arrhythmias in high-risk patients.

PubMed

Carbucicchio, Corrado; Della Bella, Paolo; Fassini, Gaetano; Trevisi, Nicola; Riva, Stefania; Giraldi, Francesco; Baratto, Francesca; Marenzi, Giancarlo; Sisillo, Erminio; Bartorelli, Antonio; Alamanni, Francesco

2009-11-01

In patients with severe cardiomyopathy, recurrent episodes of nontolerated ventricular tachycardia (VT) or electrical storm (ES) frequently cause acute heart failure and cardiac death; the suppression of the arrhythmia is therefore lifesaving, but feasibility of catheter ablation (CA) is precluded by the adverse hemodynamic conditions together with the characteristics of the arrhythmia that interdicts efficacious mapping. The use of the percutaneous cardiopulmonary support (CPS) for circulatory assistance may allow patient's stabilization and enhance efficacy and safety of CA in this emergency setting. 19 patients (19 males; mean age 61 +/- 6 years; chronic ischemic cardiomyopathy, eleven patients; primary dilated cardiomyopathy, six patients; arrhythmogenic right ventricular dysplasia/ cardiomyopathy, two patients) with recurrent nontolerated VT episodes undergoing CPS-assisted CA were retrospectively evaluated. Twelve patients had acute hemodynamic failure refractory to inotropic agents and ventilatory assistance, seven patients had undergone a failing nonconventional CA procedure. 14 patients presented with ES, and in twelve the procedure was undertaken under emergency conditions within 24 h from admission. Patients were ventilated under general anesthesia and assisted by a multidisciplinary team. The CPS system consisted in a Medtronic Bio-Medicus centrifugal pump and in a Maxima Plus oxygenator, a 15-F arterial cannula, and a 17-F venous cannula. Flows between 2 and 3 l/min were activated after induction of 56/62 forms of nontolerated VT, achieving hemodynamic stabilization in all patients. CA was mainly guided by conventional activation mapping and was effective in abolishing 45/56 supported VTs; in 10/19 patients all clinical VTs were suppressed by CA. Mean procedural time was 4 h and 20 min. Complete stabilization was achieved in 13 patients (68%) without VT recurrence during a 7-day in-hospital monitoring. A significant clinical improvement was observed in two patients (11%); one patient (5%) with persistent VT episodes acutely died after heart transplant. At a mean follow-up of 42 months (range 15-60 months), 5/18 patients (28%) were free from VT recurrence, 7/18 (39%) had a clear clinical improvement with reduced implantable cardioverter defibrillator interventions. 5/14 patients (36%) had ES recurrence; among them, three died because of acute heart failure. No serious CPS-related complications were observed. The CPS warrants acceptable hemodynamic stabilization and efficacious mapping in high-risk patients undergoing CA for unstable VT in the emergency setting. Safety and efficacy of this technique translate into significant clinical improvement in the majority of patients. Even if only relatively invasive, CPS should be reserved to patients with ES or intractable arrhythmia causing acute heart failure; moreover, the need for an experienced team of multidisciplinary operators implies that its use is restricted to selected high-competency institutions.

Real-time adjustment of ventricular restraint therapy in heart failure.

PubMed

Ghanta, Ravi K; Lee, Lawrence S; Umakanthan, Ramanan; Laurence, Rita G; Fox, John A; Bolman, Ralph Morton; Cohn, Lawrence H; Chen, Frederick Y

2008-12-01

Current ventricular restraint devices do not allow for either the measurement or adjustment of ventricular restraint level. Periodic adjustment of restraint level post-device implantation may improve therapeutic efficacy. We evaluated the feasibility of an adjustable quantitative ventricular restraint (QVR) technique utilizing a fluid-filled polyurethane epicardial balloon to measure and adjust restraint level post-implantation guided by physiologic parameters. QVR balloons were implanted in nine ovine with post-infarction dilated heart failure. Restraint level was defined by the maximum restraint pressure applied by the balloon to the epicardium at end-diastole. An access line connected the balloon lumen to a subcutaneous portacath to allow percutaneous access. Restraint level was adjusted while left ventricular (LV) end-diastolic volume (EDV) and cardiac output was assessed with simultaneous transthoracic echocardiography. All nine ovine successfully underwent QVR balloon implantation. Post-implantation, restraint level could be measured percutaneously in real-time and dynamically adjusted by instillation and withdrawal of fluid from the balloon lumen. Using simultaneous echocardiography, restraint level could be adjusted based on LV EDV and cardiac output. After QVR therapy for 21 days, LV EDV decreased from 133+/-15 ml to 113+/-17 ml (p<0.05). QVR permits real-time measurement and physiologic adjustment of ventricular restraint therapy after device implantation.

Advancements in mechanical circulatory support for patients in acute and chronic heart failure

PubMed Central

Csepe, Thomas A.

2017-01-01

Cardiogenic shock (CS) continues to have high mortality and morbidity despite advances in pharmacological, mechanical, and reperfusion approaches to treatment. When CS is refractory to medical therapy, percutaneous mechanical circulatory support (MCS) should be considered. Acute MCS devices, ranging from intra-aortic balloon pumps (IABPs) to percutaneous temporary ventricular assist devices (VAD) to extracorporeal membrane oxygenation (ECMO), can aid, restore, or maintain appropriate tissue perfusion before the development of irreversible end-organ damage. Technology has improved patient survival to recovery from CS, but in patients whom cardiac recovery does not occur, acute MCS can be effectively utilized as a bridge to long-term MCS devices and/or heart transplantation. Heart transplantation has been limited by donor heart availability, leading to a greater role of left ventricular assist device (LVAD) support. In patients with biventricular failure that are ineligible for LVAD implantation, further advancements in the total artificial heart (TAH) may allow for improved survival compared to medical therapy alone. In this review, we discuss the current state of acute and durable MCS, ongoing advances in LVADs and TAH devices, improved methods of durable MCS implantation and patient selection, and future MCS developments in this dynamic field that may allow for optimization of HF treatment. PMID:29268418

Calculated Dynamic Characteristics of a Soft-Inplane Hingeless Rotor Helicopter

NASA Technical Reports Server (NTRS)

Johnson, W.

1977-01-01

Calculated dynamic characteristics of a representative soft-inplane hingeless rotor helicopter are presented. The flight dynamics as a function of speed and gross weight are given. The requirements for accurate analytical modelling of this helicopter are established. The influence of the horizontal tail size, the rotor precone, the blade sweep, and the blade center of gravity/aerodynamic center offset on the calculated flight dynamics and aeroelastic stability are examined. The calculations show no evidence of an air resonance stability problem with this aircraft.

Dynamical investigation and parameter stability region analysis of a flywheel energy storage system in charging mode

NASA Astrophysics Data System (ADS)

Zhang, Wei-Ya; Li, Yong-Li; Chang, Xiao-Yong; Wang, Nan

2013-09-01

In this paper, the dynamic behavior analysis of the electromechanical coupling characteristics of a flywheel energy storage system (FESS) with a permanent magnet (PM) brushless direct-current (DC) motor (BLDCM) is studied. The Hopf bifurcation theory and nonlinear methods are used to investigate the generation process and mechanism of the coupled dynamic behavior for the average current controlled FESS in the charging mode. First, the universal nonlinear dynamic model of the FESS based on the BLDCM is derived. Then, for a 0.01 kWh/1.6 kW FESS platform in the Key Laboratory of the Smart Grid at Tianjin University, the phase trajectory of the FESS from a stable state towards chaos is presented using numerical and stroboscopic methods, and all dynamic behaviors of the system in this process are captured. The characteristics of the low-frequency oscillation and the mechanism of the Hopf bifurcation are investigated based on the Routh stability criterion and nonlinear dynamic theory. It is shown that the Hopf bifurcation is directly due to the loss of control over the inductor current, which is caused by the system control parameters exceeding certain ranges. This coupling nonlinear process of the FESS affects the stability of the motor running and the efficiency of energy transfer. In this paper, we investigate into the effects of control parameter change on the stability and the stability regions of these parameters based on the averaged-model approach. Furthermore, the effect of the quantization error in the digital control system is considered to modify the stability regions of the control parameters. Finally, these theoretical results are verified through platform experiments.

Percutaneous and Endoscopic Adhesiolysis in Managing Low Back and Lower Extremity Pain: A Systematic Review and Meta-analysis.

PubMed

Helm, Standiford; Racz, Gabor B; Gerdesmeyer, Ludger; Justiz, Rafael; Hayek, Salim M; Kaplan, Eugene D; El Terany, Mohamed Ahamed; Knezevic, Nebojsa Nick

2016-02-01

Chronic refractory low back and lower extremity pain is frustrating to treat. Percutaneous adhesiolysis and spinal endoscopy are techniques which can treat chronic refractory low back and lower extremity pain.Percutaneous adhesiolysis is performed by placing the catheter into the tissue plane at the ventrolateral aspect of the foramen so that medications can be injected. Adhesiolysis is used both for pain caused by scarring which is not resistant to catheter placement and other sources of pain, including inflammation in the absence of scarring.Mechanical lysis of scars with a catheter may or may not be necessary for percutaneous adhesiolysis to be effective. Spinal endoscopy allows direct visualization of the epidural space and has the possibility to use laser energy to treat pathology. A systematic review of the effectiveness of percutaneous adhesiolysis and spinal endoscopic adhesiolysis to treat chronic refractory low back and lower extremity pain. To evaluate and update the effectiveness of percutaneous adhesiolysis and spinal endoscopic adhesiolysis to treat chronic refractory low back and lower extremity pain. The available literature on percutaneous adhesiolysis and spinal endoscopic adhesiolysis in treating persistent low back and leg pain was reviewed. The quality of each article used in this analysis was assessed. The level of evidence was classified on a 5-point scale from strong, based upon multiple randomized controlled trials to weak, based upon consensus, as developed by the U.S. Preventive Services Task Force (USPSTF) and modified by ASIPP. Data sources included relevant literature identified through searches of PubMed and EMBASE from 1966 to September 2015, and manual searches of the bibliographies of known primary and review articles. Pain relief of at least 50% and functional improvement of at least 40% were the primary outcome measures. Short-term efficacy was defined as improvement of 6 months or less; whereas, long-term efficacy was defined more than 6 months. For this systematic review, 45 studies were identified. Of these, for percutaneous adhesiolysis there were 7 randomized controlled trials and 3 observational studies which met the inclusion criteria. For spinal endoscopy, there was one randomized controlled trial and 3 observational studies. Based upon 7 randomized controlled trials showing efficacy, with no negative trials, there is Level I or strong evidence of the efficacy of percutaneous adhesiolysis in the treatment of chronic refractory low back and lower extremity pain. Based upon one high-quality randomized controlled trial, there is Level II to III evidence supporting the use of spinal endoscopy in treating chronic refractory low back and lower extremity pain. The evidence is Level I or strong that percutaneous adhesiolysis is efficacious in the treatment of chronic refractory low back and lower extremity pain. Percutaneous adhesiolysis may be considered as a first-line treatment for chronic refractory low back and lower extremity pain. The evidence is Level II to III that spinal endoscopy is effective in the treatment of chronic refractory low back and lower extremity pain. Spinal pain, chronic low back pain, post lumbar surgery syndrome, epidural scarring, adhesiolysis, endoscopy, radicular pain.

Percutaneous Facet Screw Fixation in the Treatment of Symptomatic Recurrent Lumbar Facet Joint Cyst: A New Technique

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

Amoretti, Nicolas, E-mail: amorettinicolas@yahoo.fr; Gallo, Giacomo, E-mail: giacomo.gallo83@gmail.com; Bertrand, Anne-Sophie, E-mail: asbertrand3@hotmail.com

We present a case of percutaneous treatment of symptomatic recurrent lumbar facet joint cyst resistant to all medical treatments including facet joint steroid injection. Percutaneous transfacet fixation was then performed at L4–L5 level with a cannulated screw using CT and fluoroscopy guidance. The procedure time was 30 min. Using the visual analog scale (VAS), pain decreased from 9.5, preoperatively, to 0 after the procedure. At 6-month follow-up, an asymptomatic cystic recurrence was observed, which further reduced at the 1-year follow-up. Pain remained stable (VAS at 0) during all follow-ups. CT- and fluoroscopy-guided percutaneous cyst rupture associated with facet screw fixation couldmore » be an alternative to surgery in patients suffering from a symptomatic recurrent lumbar facet joint cyst.« less

Percutaneous discal cyst rupture in a professional football player using sublaminar epidural injection for thecal sac displacement.

PubMed

Friedman, Michael V; Park, Andrew; Bumpass, David; Jennings, Jack W; Matava, Matthew J

2015-01-01

A case of percutaneous discal cyst rupture in a 25-year-old professional American football player is reported. The patient presented with a 3-day history of severe left-sided back pain. Magnetic resonance imaging examination demonstrated a discal cyst effacing the left L4-L5 lateral recess, with interposed thecal sac. A sublaminar epidural injection was performed displacing the thecal sac, exposing the discal cyst, and allowing for percutaneous perforation. The patient had complete resolution of symptoms after discal cyst rupture and was able to compete in a professional football game 3 days later. Computed tomography-guided percutaneous rupture is a therapeutic modality that may be considered for treatment of a symptomatic discal cyst. Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.

Unprotected Left Main Disease: Indications and Optimal Strategies for Percutaneous Intervention.

PubMed

Li, Jun; Patel, Sandeep M; Parikh, Manish A; Parikh, Sahil A

2016-03-01

Although the incidence of left main (LM) coronary artery disease is relatively low in patients undergoing routine angiography, it is a common presentation in patients with acute coronary syndromes. With the current interventional tools and techniques, percutaneous intervention for LM disease has become a viable alternative to the traditional coronary artery bypass grafting. Factors that contribute to the success and appropriateness of percutaneous intervention for LM disease include coronary anatomy and patient-specific factors such as left ventricular function. Multiple considerations should be taken into account prior to intervention, including hemodynamic support if necessary, intravascular imaging to guide therapy, and stent technique. This review provides an overview of the current body of literature to support the use of percutaneous intervention in LM disease and serves as guideline for the interventionalist approaching LM revascularization.

Treatment of Patellar Tendinopathy Refractory to Surgical Management Using Percutaneous Ultrasonic Tenotomy and Platelet-Rich Plasma Injection: A Case Presentation.

PubMed

Nanos, Katherine N; Malanga, Gerard A

2015-12-01

Chronic proximal patellar tendinopathy is a common condition in sports medicine that may be refractory to nonoperative treatments, including activity modification, medications, and comprehensive rehabilitation. Percutaneous ultrasonic tenotomy is a recently developed technique designed to cut and debride tendinopathic tissue, thus promoting pain relief and functional recovery. We present a case of a collegiate athlete with chronic proximal patellar tendinopathy who was effectively treated with percutaneous ultrasonic tenotomy after not responding to extensive nonoperative treatment, surgical debridement, and platelet-rich plasma injections. Percutaneous ultrasonic tenotomy can be considered as a treatment option in patients presenting with refractory proximal patellar tendinopathy, including those who do not respond to previous operative intervention. Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Perforated Duodenal Ulcer in High Risk Patients: Is Percutaneous Drainage Justified?

PubMed Central

Saber, Aly; Gad, Mohammad A; Ellabban, Gouda M

2012-01-01

Background: Conservative treatment was recommended as the treatment of choice in perforated acute peptic ulcer. Here, we adjunct percutaneous peritoneal drainage with nonoperative conservative treatment in high risk elderly patients with perforated duodenal ulcer. Aim: The work was to study the efficacy of percutaneous peritoneal drainage under local anesthesia supported by conservative measures in high risk elderly patients, according to the American Society of Anesthesiologists grading, with perforated duodenal ulcer. Patients and Methods: Twenty four high risk patients with age >65 years having associated medical illness with evidence of perforated duodenal ulcer. Results: The overall morbidity and mortality were comparable with those treated by conservative measures alone. Conclusion: In high risk patients with perforated peptic ulcer and established peritonitis, percutaneous peritoneal drainage under local anesthesia seems to be effective with least operative trauma and mortality rate. PMID:22393546

Promotion of artery occlusion in dogs by percutaneous rotational atherectomy.

PubMed

Hou, Chuan-Ju; Zhang, Duan-Zhen; Wang, Qi-Guang; Cui, Chun-Sheng; Kuang, Li; Chen, Bing; Wang, Yang

2014-07-01

This study aims to offer experimental data and indirect evidences for the application of percutaneous rotational atherectomy to treat patent ductus arteriosus (PDA). Eleven dogs (6 male dogs and 5 female dogs; aged 14-20 months, with an average of 16.7±3.2 months; weight 20-25 kg, with an average of 22.7±2.5 kg) were enrolled in this study. The diameters of the left and right arteries ranged from 3.2 to 4.8 mm (average 3.9±0.6 mm) on percutaneous angiography. Percutaneous rotational atherectomy with proper rotablator (the size was 1-1.5 mm larger than the artery diameter) was performed in the arterial intima. After 4 weeks from percutaneous rotational atherectomy, arteriography was conducted to observe the changes in artery diameter. Then all dogs were sacrificed and the pathologic examination was conducted on the left and right axillary arteries. There were obvious changes with different degrees in 22 arteries, including 8 arteries with complete occlusion and 12 arteries with stenosis (≥2/3, 1/2, and 1/3 stenosis in 4, 4, and 4 arteries, respectively). The occlusion rate was 36.4% and the total effective rate was 90.9%. It was considered failure in other 2 arteries with <1/3 of stenosis. Percutaneous rotational atherectomy of arterial intima can promote the occlusion of arteries. This has provided a new choice for the treatment of PDA. Copyright © 2014 Elsevier Inc. All rights reserved.

In-hospital cost comparison between percutaneous pulmonary valve implantation and surgery

PubMed Central

Mishra, Vinod; Lewandowska, Milena; Andersen, Jack Gunnar; Andersen, Marit Helen; Lindberg, Harald; Døhlen, Gaute; Fosse, Erik

2017-01-01

Abstract OBJECTIVES: Today, both surgical and percutaneous techniques are available for pulmonary valve implantation in patients with right ventricle outflow tract obstruction or insufficiency. In this controlled, non-randomized study the hospital costs per patient of the two treatment options were identified and compared. METHODS: During the period of June 2011 until October 2014 cost data in 20 patients treated with the percutaneous technique and 14 patients treated with open surgery were consecutively included. Two methods for cost analysis were used, a retrospective average cost estimate (overhead costs) and a direct prospective detailed cost acquisition related to each individual patient (patient-specific costs). RESULTS: The equipment cost, particularly the stents and valve itself was by far the main cost-driving factor in the percutaneous pulmonary valve group, representing 96% of the direct costs, whereas in the open surgery group the main costs derived from the postoperative care and particularly the stay in the intensive care department. The device-related cost in this group represented 13.5% of the direct costs. Length-of-stay-related costs in the percutaneous group were mean $3885 (1618) and mean $17 848 (5060) in the open surgery group. The difference in postoperative stay between the groups was statistically significant (P≤ 0.001). CONCLUSIONS: Given the high postoperative cost in open surgery, the percutaneous procedure could be cost saving even with a device cost of more than five times the cost of the surgical device. PMID:28007875

Percutaneous adhesiolysis procedures in the medicare population: analysis of utilization and growth patterns from 2000 to 2011.

PubMed

Manchikanti, Laxmaiah; Helm Ii, Standiford; Pampati, Vidyasagar; Racz, Gabor B

2014-01-01

Multiple reviews have shown that interventional techniques for chronic pain have increased dramatically over the years. Of these interventional techniques, both sacroiliac joint injections and facet joint interventions showed explosive growth, followed by epidural procedures. Percutaneous adhesiolysis procedures have not been assessed for their utilization patterns separately from epidural injections. An analysis of the utilization patterns of percutaneous adhesiolysis procedures in managing chronic low back pain in the Medicare population from 2000 to 2011. To assess the utilization and growth patterns of percutaneous adhesiolysis in managing chronic low back pain. The study was performed utilizing the Centers for Medicare and Medicaid Services (CMS) Physician Supplier Procedure Summary Master of Fee-For-Service (FFS) Data from 2000 to 2011. Percutaneous adhesiolysis procedures increased 47% with an annual growth rate of 3.6% in the FFS Medicare population from 2000 to 2011. These growth rates are significantly lower than the growth rates for sacroiliac joint injections (331%), facet joint interventions (308%), and epidural injections (130%), but substantially lower than lumbar transforaminal injections (665%) and lumbar facet joint neurolysis (544%). Study limitations include lack of inclusion of Medicare Advantage patients. In addition, the statewide data is based on claims which may include the contiguous or other states. Percutaneous adhesiolysis utilization increased moderately in Medicare beneficiaries from 2000 to 2011. Overall, there was an increase of 47% in the utilization of adhesiolysis procedures per 100,000 Medicare beneficiaries, with an annual geometric average increase of 3.6%.

Percutaneous Treatment of Splenic Cystic Echinococcosis: Results of 12 Cases

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

Akhan, Okan, E-mail: akhano@tr.net; Akkaya, Selçuk, E-mail: selcuk.akkaya85@gmail.com; Dağoğlu, Merve Gülbiz, E-mail: drmgkartal@gmail.com

PurposeCystic echinococcosis (CE) in the spleen is a rare disease even in endemic regions. The aim of this study was to examine the efficacy of percutaneous treatment for splenic CE.Materials and MethodsTwelve patients (four men, eight women) with splenic CE were included in this study. For percutaneous treatment, CE1 and CE3A splenic hydatid cysts were treated with either the PAIR (puncture, aspiration, injection, respiration) technique or the catheterization technique.ResultsEight of the hydatid cysts were treated with the PAIR technique and four were treated with catheterization. The volume of all cysts decreased significantly during the follow-up period. No complication occurred inmore » seven of 12 patients. Abscess developed in four patients. Two patients underwent splenectomy due to cavity infection developed after percutaneous treatment, while the spleen was preserved in 10 of 12 patients. Total hospital stay was between 1 and 18 days. Hospital stay was longer and the rate of infection was higher in the catheterization group. Follow-up period was 5–117 months (mean, 44.8 months), with no recurrence observed.ConclusionThe advantages of the percutaneous treatment are its minimal invasive nature, short hospitalization duration, and its ability to preserve splenic tissue and function. As the catheterization technique is associated with higher abscess risk, we suggest that the PAIR procedure should be the first percutaneous treatment option for splenic CE.« less

Ultrasound-guided percutaneous bone drilling for the treatment of lateral epicondylitis.

PubMed

Yoo, Sang Ho; Cha, Jang Gyu; Lee, Bo Ra

2018-01-01

To determine the clinical efficacy of sonographically-guided percutaneous bone drilling of the lateral epicondyle (LE) for the treatment of patients with LE. We included 24 patients with LE who reported pain in this study. All patients underwent sonographically-guided percutaneous bone drilling of the lateral epicondyle. Follow-up sonography and physical examinations were performed 1, 3 and 6 months after the procedure. The outcome measures included sonographic findings, visual analogue scale (VAS) score, maximum voluntary grip strength (MVGS) and patient-related tennis elbow evaluation (PRTEE) score. None of the patients had immediate complications during the procedure. The area of the extensor carpi radialis brevis (ECRB) tears decreased significantly at 1 month and declined gradually over the remaining 5 months of the study (p < 0.001). The mean pain VAS score was significantly lower at 6 months than preoperatively (respectively; p < 0.001). The mean MVGS increased significantly between pretreatment and 6 months post-treatment (p < 0.001), whereas the PRTEE score decreased significantly during the same period (p < 0.001). Sonographically-guided percutaneous drilling is a quick and safe treatment option for LE that can be performed in an outpatient setting. • Percutaneous drilling of the lateral condyle is effective for the treatment of LE. • The area of ECRB tears can be measured by US-guided saline injection. • US-guided percutaneous drilling is a quick and safe treatment option for LE.

Challenging the wisdom of puncture at the calyceal fornix in percutaneous nephrolithotripsy: feasibility and safety study with 137 patients operated via a non-calyceal percutaneous track.

PubMed

Kyriazis, Iason; Kallidonis, Panagiotis; Vasilas, Marinos; Panagopoulos, Vasilios; Kamal, Wissam; Liatsikos, Evangelos

2017-05-01

To present our experience with a central, non-calyceal puncture protocol for percutaneous nephrolithotripsy (PCNL) in an attempt to challenge the opinion of worldwide adopted calyceal puncture as the less traumatic site of percutaneous entrance into the collecting system. During 2012, a total of 137 consecutive, unselected patients were subjected to PCNL in our department. Non-calyceal punctures were performed to all cases and followed by subsequent track dilations up to 30 Fr. Perioperative and postoperative data were prospectively collected and analyzed. Mean operative time (from skin puncture to nephrostomy tube placement) was 48 min. Patients with single, multiple and staghorn stones had primary stone-free rates of 89.2, 80.4 and 66.7 % after PCNL, respectively. The overall complication rate was 10.2 %, while bleeding complications were minimal. Only 4 patients (2.9 %) required blood transfusion. Five patients (3.6 %) had Clavien Grade IIIa complications requiring an intervention for their management and none Grade IV or V. Despite the absence of evidence that non-calyceal percutaneous tracts could be a risk factor for complications, the concept of calyceal puncture has been worldwide adopted by PCNL surgeons as the sole safe percutaneous entrance into the collective system. Based on our experience, other pathways than the worldwide recognized rule, calyceal puncture, are possible and probably not as dangerous as has been previously stated.

Assessment of stability during gait in patients with spinal deformity-A preliminary analysis using the dynamic stability margin.

PubMed

Simon, Anne-Laure; Lugade, Vipul; Bernhardt, Kathie; Larson, A Noelle; Kaufman, Kenton

2017-06-01

Daily living activities are dynamic, requiring spinal motion through space. Current assessment of spinal deformities is based on static measurements from full-spine standing radiographs. Tools to assess dynamic stability during gait might be useful to enhance the standard evaluation. The aim of this study was to evaluate gait dynamic imbalance in patients with spinal deformity using the dynamic stability margin (DSM). Twelve normal subjects and 17 patients with spinal deformity were prospectively recruited. A kinematic 3D gait analysis was performed for the control group (CG) and the spinal deformity group (SDG). The DSM (distance between the extrapolated center of mass and the base of support) and time-distance parameters were calculated for the right and left side during gait. The relationship between DSM and step length was assessed using three variables: gait stability, symmetry, and consistency. Variables' accuracy was validated by a discriminant analysis. Patients with spinal deformity exhibited gait instability according to the DSM (0.25m versus 0.31m) with decreased velocity (1.1ms -1 versus 1.3ms -1 ) and decreased step length (0.32m versus 0.38m). According to the discriminant analysis, gait stability was the more accurate variable (area under the curve AUC=0.98) followed by gait symmetry and consistency. However, gait consistency showed 100% of specificity, sensitivity, and accuracy of precision. The DSM showed that patients with spinal malalignment exhibit decreased gait stability, symmetry, and consistency besides gait time-distance parameter changes. Additional work is required to determine how to apply the DSM for preoperative and postoperative spinal deformity management. Copyright © 2017. Published by Elsevier B.V.

Military personnel with self-reported ankle injuries do not demonstrate deficits in dynamic postural stability or landing kinematics.

PubMed

Bansbach, Heather M; Lovalekar, Mita T; Abt, John P; Rafferty, Deirdre; Yount, Darcie; Sell, Timothy C

2017-08-01

The odds of sustaining non-contact musculoskeletal injuries are higher in Special Operations Forces operators than in infantry soldiers. The ankle is one of the most commonly injured joints, and once injured can put individuals at risk for reinjury. The purpose of this study was to determine if any differences in postural stability and landing kinematics exist between operators with a self-reported ankle injury in the past one year and uninjured controls. A total of 55 Special Operations Forces operators were included in this analysis. Comparisons were made between operators with a self-reported ankle injury within one-year of their test date (n=11) and healthy matched controls (n=44). Comparisons were also made between injured and uninjured limbs within the injured group. Dynamic postural stability and landing kinematics at the ankle, knee, and hip were assessed during a single-leg jump-landing task. Comparisons were made between groups with independent t-tests and within the injured group between limbs using paired t-tests. There were no significant differences in dynamic postural stability index or landing kinematics between the injured and uninjured groups. Anterior-posterior stability index was significantly higher on the uninjured limb compared to the injured limb within the injured group (P=0.02). Single ankle injuries sustained by operators may not lead to deficits in dynamic postural stability. Dynamic postural stability index and landing kinematics within one year after injury were either not affected by the injuries reported, or injured operators were trained back to baseline measures through rehabilitation and daily activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nonlinear vibrations and dynamic stability of viscoelastic orthotropic rectangular plates

NASA Astrophysics Data System (ADS)

Eshmatov, B. Kh.

2007-03-01

This paper describes the analyses of the nonlinear vibrations and dynamic stability of viscoelastic orthotropic plates. The models are based on the Kirchhoff-Love (K.L.) hypothesis and Reissner-Mindlin (R.M.) generalized theory (with the incorporation of shear deformation and rotatory inertia) in geometrically nonlinear statements. It provides justification for the choice of the weakly singular Koltunov-Rzhanitsyn type kernel, with three rheological parameters. In addition, the implication of each relaxation kernel parameter has been studied. To solve problems of viscoelastic systems with weakly singular kernels of relaxation, a numerical method has been used, based on quadrature formulae. With a combination of the Bubnov-Galerkin and the presented method, problems of nonlinear vibrations and dynamic stability in viscoelastic orthotropic rectangular plates have been solved, according to the K.L. and R.M. hypotheses. A comparison of the results obtained via these theories is also presented. In all problems, the convergence of the Bubnov-Galerkin method has been investigated. The implications of material viscoelasticity on vibration and dynamic stability are presented graphically.

Investigation on Stability in Roll of Square Section Missile at High Angle of Attack

NASA Astrophysics Data System (ADS)

Tao, Yang; Fan, Zhaolin; Wu, Jifei; Wu, Wenhua

An experimental investigation of the stability in roll of a square section missile at high incidence was conducted in FL-23 wind tunnel. Dynamic motions were obtained on a square section missile that is free to rotate about its longitudinal axis. Different dynamic rolling motions were observed depending on the incidence of the model sting. These dynamic regimes include damped oscillations, quasi-limit-cycle wing-rock motion, and constant rolling. A coupling numerical method was established by solving the fluid dynamics equations and the rigid-body dynamics equations synchronously in order to predict the onset and the development of uncommented motions and then explore the unsteady movement characteristics of the aircraft. The study indicates that the aircraft loss stability at high incidence is caused by the asymmetric vertex on the level fin tip liftoff and attach alternately. The computation results are in line with the experiment results.

A simple, stable, and accurate linear tetrahedral finite element for transient, nearly, and fully incompressible solid dynamics: A dynamic variational multiscale approach [A simple, stable, and accurate tetrahedral finite element for transient, nearly incompressible, linear and nonlinear elasticity: A dynamic variational multiscale approach

DOE PAGES

Scovazzi, Guglielmo; Carnes, Brian; Zeng, Xianyi; ...

2015-11-12

Here, we propose a new approach for the stabilization of linear tetrahedral finite elements in the case of nearly incompressible transient solid dynamics computations. Our method is based on a mixed formulation, in which the momentum equation is complemented by a rate equation for the evolution of the pressure field, approximated with piece-wise linear, continuous finite element functions. The pressure equation is stabilized to prevent spurious pressure oscillations in computations. Incidentally, it is also shown that many stabilized methods previously developed for the static case do not generalize easily to transient dynamics. Extensive tests in the context of linear andmore » nonlinear elasticity are used to corroborate the claim that the proposed method is robust, stable, and accurate.« less

A simple, stable, and accurate linear tetrahedral finite element for transient, nearly, and fully incompressible solid dynamics: A dynamic variational multiscale approach [A simple, stable, and accurate tetrahedral finite element for transient, nearly incompressible, linear and nonlinear elasticity: A dynamic variational multiscale approach

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

Scovazzi, Guglielmo; Carnes, Brian; Zeng, Xianyi

Here, we propose a new approach for the stabilization of linear tetrahedral finite elements in the case of nearly incompressible transient solid dynamics computations. Our method is based on a mixed formulation, in which the momentum equation is complemented by a rate equation for the evolution of the pressure field, approximated with piece-wise linear, continuous finite element functions. The pressure equation is stabilized to prevent spurious pressure oscillations in computations. Incidentally, it is also shown that many stabilized methods previously developed for the static case do not generalize easily to transient dynamics. Extensive tests in the context of linear andmore » nonlinear elasticity are used to corroborate the claim that the proposed method is robust, stable, and accurate.« less

Maximum Lyapunov exponents as predictors of global gait stability: a modelling approach.

PubMed

Bruijn, Sjoerd M; Bregman, Daan J J; Meijer, Onno G; Beek, Peter J; van Dieën, Jaap H

2012-05-01

To examine the stability of human walking, methods such as local dynamic stability have been adopted from dynamical systems theory. Local dynamic stability is calculated by estimating maximal finite time Lyapunov exponents (λ(S) and λ(L)), which quantify how a system responds continuously to very small (i.e. "local") perturbations. However, it is unknown if, and to what extent, these measures are correlated to global stability, defined operationally as the probability of falling. We studied whether changes in probability of falling of a simple model of human walking (a so-called dynamic walker) could be predicted from maximum finite time Lyapunov exponents. We used an extended version of the simplest walking model with arced feet and a hip spring. This allowed us to change the probability of falling of the model by changing either the foot radius, the slope at which the model walks, the stiffness of the hip spring, or a combination of these factors. Results showed that λ(S) correlated fairly well with global stability, although this relationship was dependent upon differences in the distance between initial nearest neighbours on the divergence curve. A measure independent of such changes (the log(distance between initially nearest neighbours after 50 samples)) correlated better with global stability, and, more importantly, showed a more consistent relationship across conditions. In contrast, λ(L) showed either weak correlations, or correlations opposite to expected, thus casting doubt on the use of this measure as a predictor of global gait stability. Our findings support the use of λ(S), but not of λ(L), as measure of human gait stability. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

U31: vehicle stability and dynamics electronic stability control final report.

DOT National Transportation Integrated Search

2011-09-01

A team led by NTRCI is working to improve the roll and yaw stability of heavy duty combination trucks through developing stability algorithms, assembling demonstration hardware, and investigating robust wireless communication. : Modern electronic sta...

Clinical investigations of polymethylmethacrylate cement viscosity during vertebroplasty and related in vitro measurements

PubMed Central

Boger, A.; Schenk, B.; Heini, P. F.

2009-01-01

Percutaneous vertebroplasty, comprising an injection of polymethylmethacrylate (PMMA) into vertebral bodies, is a practical procedure for the stabilization of osteoporotic compression fractures as well as other weakening lesions. Cement leakage is considered to be one of the major and most severe complications during percutaneous vertebroplasty. The viscosity of the material plays a key role in this context. In order to enhance the safety for the patient, a rheometer system was developed to measure the cement viscosity intraoperatively. For this development, it is of great importance to know the proper viscosity to start the procedure determined by experienced surgeons and the relation between the time period when different injection devices are used and the cement viscosity. The purpose of the study was to investigate the viscosity ranges for different injection systems during conventional vertebroplasty. Clinically observed viscosity values and related time periods showed high scattering. In order to get a better understanding of the clinical observations, cement viscosity during hardening at different ambient temperatures and by simulation of the body temperature was investigated in vitro. It could be concluded, that the direct viscosity assessment with a rheometer during vertebroplasty can help clinicians to define a lower threshold viscosity and thereby decrease the risk of leakage and make adjustments to their injection technique in real time. Secondly, the acceleration in hardening of PMMA-based cements at body temperature can be useful in minimizing leakages by addressing them with a short injection break. PMID:19479285

Comparison of Percutaneous Cementoplasty with and Without Interventional Internal Fixation for Impending Malignant Pathological Fracture of the Proximal Femur

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

Tian, Qing-Hua, E-mail: ddqinghua-tian@163.com; He, Cheng-Jian, E-mail: tianhechengjian@163.com; Wu, Chun-Gen, E-mail: 649514608@qq.com

PurposeTo compare the efficacy of percutaneous cementoplasty (PCP) with and without interventional internal fixation (IIF) on malignant impending pathological fracture of proximal femur.MethodsA total of 40 patients with malignant impending pathological fracture of proximal femur were selected for PCP and IIF (n = 19, group A) or PCP alone (n = 21, group B) in this non-randomized prospective study. Bone puncture needles were inserted into the proximal femur, followed by sequential installation of the modified trocar inner needles through the puncture needle sheath. Then, 15–45 ml cement was injected into the femur lesion.ResultsThe overall excellent and good pain relief rate during follow-ups were significantly highermore » in group A than that in group B (89 vs. 57 %, P = 0.034). The average change of VAS, ODI, KPS, and EFES in group A were significantly higher than those in group B at 1-, 3-, 6-month, 1-year (P < 0.05). Meanwhile, The stability of the treated femur was significantly higher in group A than that in group B (P < 0.05).ConclusionPCP and IIF were not only a safe and effective procedure, but resulted in greater pain relief, bone consolidation, and also reduced the risk of fracture than the currently recommended approach of PCP done on malignant proximal femoral tumor.« less

Experimental ex-vivo validation of PMMA-based bone cements loaded with magnetic nanoparticles enabling hyperthermia of metastatic bone tumors

NASA Astrophysics Data System (ADS)

Harabech, Mariem; Kiselovs, Normunds Rungevics; Maenhoudt, Wim; Crevecoeur, Guillaume; Van Roost, Dirk; Dupré, Luc

2017-05-01

Percutaneous vertebroplasty comprises the injection of Polymethylmethacrylate (PMMA) bone cement into vertebrae and can be used for the treatment of compression fractures of vertebrae. Metastatic bone tumors can cause such compression fractures but are not treated when injecting PMMA-based bone cement. Hyperthermia of tumors can on the other hand be attained by placing magnetic nanoparticles (MNPs) in an alternating magnetic field (AMF). Loading the PMMA-based bone cement with MNPs could both serve vertebra stabilization and metastatic bone tumor hyperthermia when subjecting this PMMA-MNP to an AMF. A dedicated pancake coil is designed with a self-inductance of 10 μH in series with a capacitance of 0.1 μF that acts as resonant inductor-capacitor circuit to generate the AMF. The thermal rise is appraised in beef vertebra placed at 10 cm from the AMF generating circuit using optical temperatures sensors, i.e. in the center of the PMMA-MNP bone cement, which is located in the vicinity of metastatic bone tumors in clinical applications; and in the spine, which needs to be safeguarded to high temperature exposures. Results show a temperature rise of about 7 °C in PMMA-MNP whereas the temperature rise in the spine remains limited to 1 °C. Moreover, multicycles heating of PMMA-MNP is experimentally verified, validating the technical feasibility of having PMMA-MNP as basic component for percutaneous vertebroplasty combined with hyperthermia treatment of metastatic bone tumors.

Determination of Static and Dynamic Stability Derivatives Using Beggar

DTIC Science & Technology

2008-03-01

applies a symmetric Gauss - Seidel method , which solves the generic equation [A]x = b for x by dividing [A] into [A] = ([D][L])[U ] (2.68) 37 where D is...oscillations. Convergence studies on each of these parameters were performed to ensure both convergence and solution independence. Roll stability derivatives...aerodynamic stability parame- ters made dynamic solutions more difficult to compute and less reliable, but modern methods and resources are making this process

Complex Dynamical Behavior in Hybrid Systems

DTIC Science & Technology

2012-09-29

stability for a class of hybrid dynamical systems via averaging”, Mathematics of Control , Signals, and Systems , vol. 23, no. 4, pp...no. 7, pp. 1636-1649, 2011. J9. A.R. Teel and L. Marconi, `` Stabilization for a class of minimum phase hybrid systems under an average dwell- time ...functions for L2 and input-to-state stability in a class of quantized control systems ”, 50th IEEE Conference on Decision and Control , Dec.

Interventional radiology in the elderly

PubMed Central

Katsanos, Konstantinos; Ahmad, Farhan; Dourado, Renato; Sabharwal, Tarun; Adam, Andreas

2009-01-01

Interventional radiological percutaneous procedures are becoming all the more important in the curative or palliative management of elderly frail patients with multiple underlying comorbidities. They may serve either as alternative primary minimally invasive therapies or adjuncts to traditional surgical treatments. The present report provides a concise review of the most important interventional radiological procedures with a special focus on the treatment of the primary debilitating pathologies of the elderly population. The authors elaborate on the scientific evidence and latest developments of thermoablation of solid organ malignancies, palliative stent placement for gastrointestinal tract cancer, airway stenting for tracheobronchial strictures, endovascular management of aortic and peripheral arterial vascular disease, and cement stabilization of osteoporotic vertebral fractures. The added benefits of high technical and clinical success coupled with lower procedural mortality and morbidity are highlighted. PMID:19503761

[Clinical and radiographic evaluation of a new percutaneous technique for moderate to severe hallux valgus deformity].

PubMed

Vélez-de Lachica, J C; Valdez-Jiménez, L A; Inzunza-Sánchez, J M

2017-01-01

Hallux valgus is considered the most common musculoskeletal deformity, with a prevalence of 88%. There are more than 130 surgical techniques for its treatment; currently, percutaneous ones are popular; however, they do not take into account the metatarsal-phalangeal correction angle. The aim of this study is to propose a modified technique for the correction of the percutaneous metatarsal-phalangeal and inter-metatarsal angles and to evaluate its clinical and radiological results. An experimental, prospective and longitudinal study in 10 patients with moderate to severe hallux valgus according to the classification of Coughlin and Mann were collected; the results were evaluated with the AOFAS scale at 15, 30, 60 and 90 days. The McBride technique and the technique of percutaneous anchor with the proposed amendment were performed. The AOFAS scale was applied as described, finding a progressive increase of the rating; the average correction of the inter-metatarsal angle was 8.8 degrees and of the metatarsal-phalangeal, 9.12. The modified technique of percutaneous anchor showed clear clinical and radiographic improvements in the short term. Our modified technique is proposed for future projects, including a large sample with long-term follow-up.

Transoral approach for percutaneous vertebroplasty in the treatment of osteolytic tumor lesions of the lateral mass of the atlas: feasibility and initial experience in 2 patients.

PubMed

Clarençon, Frédéric; Cormier, Evelyne; Pascal-Moussellard, Hugues; Maldent, Jean-Baptiste; Pichon, Soizic; Le Jean, Lise; Ikka, Léon; Chiras, Jacques

2013-02-01

Case series. To report our early experience of percutaneous vertebro-plasty via a transoral approach of the lesions of the lateral mass of C1. Percutaneous vertebroplasty has gained acceptance for the treatment of osteolytic lesions of the spine. However, scant data are available on the percutaneous vertebroplasty of the C1 lesions. Two patients (a 74-yr-old female and a 53-yr-old male) presenting respectively a metastasis of the left lateral mass of C1 from a pancreatic adenocarcinoma and a hemangioma of the left lateral mass of C1 underwent a percutaneous vertebroplasty via a transoral approach in a hybrid angio suite associating a monoplane flat panel and a computed tomography scan, using polymethylmetacrilate bone cement.For the second patient, a nondetachable balloon was used to protect the vertebral artery from cement leakage. Satisfactory filing of the lesions was obtained in both patients. No complication was recorded. Both patients experienced pain improvement. Transoral approach for the treatment of osteolytic tumor lesions of the lateral mass of the atlas is feasible and seems to be a safe and effective technique.

Percutaneous tracheostomy in patients with cervical spine fractures--feasible and safe.

PubMed

Ben Nun, Alon; Orlovsky, Michael; Best, Lael Anson

2006-08-01

The aim of this study is to evaluate the short and long-term results of percutaneous tracheostomy in patients with documented cervical spine fracture. Between June 2000 and September 2005, 38 consecutive percutaneous tracheostomy procedures were performed on multi-trauma patients with cervical spine fracture. Modified Griggs technique was employed at the bedside in the general intensive care department. Staff thoracic surgeons and anesthesiologists performed all procedures. Demographics, anatomical conditions, presence of co-morbidities and complication rates were recorded. The average operative time was 10 min (6-15). Two patients had minor complications. One patients had minor bleeding (50 cc) and one had mild cellulitis. Nine patients had severe paraparesis or paraplegia prior to the PCT procedure and 29 were without neurological damage. There was no PCT related neurological deterioration. Twenty-eight patients were discharged from the hospital, 21 were decannulated. The average follow-up period was 18 months (1-48). There was no delayed, procedure related, complication. These results demonstrate that percutaneous tracheostomy is feasible and safe in patients with cervical spine fracture with minimal short and long-term morbidity. We believe that percutaneous tracheostomy is the procedure of choice for patients with cervical spine fracture who need prolonged ventilatory support.

Percutaneous dilatational versus conventional surgical tracheostomy in intensive care patients

PubMed Central

Youssef, Tarek F.; Ahmed, Mohamed Rifaat; Saber, Aly

2011-01-01

Background: Tracheostomy is usually performed in patients with difficult weaning from mechanical ventilation or some catastrophic neurologic insult. Conventional tracheostomy involves dissection of the pretracheal tissues and insertion of the tracheostomy tube into the trachea under direct vision. Percutaneous dilatational tracheostomy is increasingly popular and has gained widespread acceptance in many intensive care unit and trauma centers. Aim: Aim of the study was to compare percutaneous dilatational tracheostomy versus conventional tracheostomy in intensive care patients. Patients and Methods: 64 critically ill patients admitted to intensive care unit subjected to tracheostomy and randomly divided into two groups; percutaneous dilatational tracheostomy and conventional tracheostomy. Results: Mean duration of the procedure was similar between the two procedures while the mean size of tracheostomy tube was smaller in percutaneous technique. In addition, the Lowest SpO2 during procedure, PaCO2 after operation and intra-operative bleeding for both groups were nearly similar without any statistically difference. Postoperative infection after 7 days seen to be statistically lowered and the length of scar tend to be smaller among PDT patients. Conclusion: PDT technique is effective and safe as CST with low incidence of post operative complication. PMID:22361497

The effect of volatility on percutaneous absorption.

PubMed

Rouse, Nicole C; Maibach, Howard I

2016-01-01

Topically applied chemicals may volatilize, or evaporate, from skin leaving behind a chemical residue with new percutaneous absorptive capabilities. Understanding volatilization of topical medications, such as sunscreens, fragrances, insect repellants, cosmetics and other commonly applied topicals may have implications for their safety and efficacy. A systematic review of English language articles from 1979 to 2014 was performed using key search terms. Articles were evaluated to assess the relationship between volatility and percutaneous absorption. A total of 12 articles were selected and reviewed. Key findings were that absorption is enhanced when coupled with a volatile substance, occlusion prevents evaporation and increases absorption, high ventilation increases volatilization and reduces absorption, and pH of skin has an affect on a chemical's volatility. The articles also brought to light that different methods may have an affect on volatility: different body regions; in vivo vs. in vitro; human vs. Data suggest that volatility is crucial for determining safety and efficacy of cutaneous exposures and therapies. Few articles have been documented reporting evaporation in the context of percutaneous absorption, and of those published, great variability exists in methods. Further investigation of volatility is needed to properly evaluate its role in percutaneous absorption.

Hamiltonian dynamics for complex food webs

NASA Astrophysics Data System (ADS)

Kozlov, Vladimir; Vakulenko, Sergey; Wennergren, Uno

2016-03-01

We investigate stability and dynamics of large ecological networks by introducing classical methods of dynamical system theory from physics, including Hamiltonian and averaging methods. Our analysis exploits the topological structure of the network, namely the existence of strongly connected nodes (hubs) in the networks. We reveal new relations between topology, interaction structure, and network dynamics. We describe mechanisms of catastrophic phenomena leading to sharp changes of dynamics and hence completely altering the ecosystem. We also show how these phenomena depend on the structure of interaction between species. We can conclude that a Hamiltonian structure of biological interactions leads to stability and large biodiversity.

Dynamic stabilization of the Rayleigh-Taylor instability of miscible liquids and the related "frozen waves"

NASA Astrophysics Data System (ADS)

Wolf, Gerd Gerhard H.

2018-02-01

Superimposed miscible liquids, the heavier one on top, when subjected to vibrations vertical to their interface (dynamic stabilization), can only be maintained for a certain period. A mechanism is presented explaining the resulting process of degradation and "anomalous diffusion" through that interface. Superimposed liquids, the lighter one on top, exposed to horizontal vibrations, develop a saw-tooth-like pattern called "frozen waves." These are subject to conditions similar to those of dynamic stabilization and, if miscible, thus can also only be maintained for a certain period. A further analysis of these processes would be desirable, also in view of their relation to analogue phenomena.

Stability limits and dynamics of nonaxisymmetric liquid bridges

NASA Technical Reports Server (NTRS)

Alexander, J. Iwan D.; Resnik, Andy; Kaukler, William F.

1993-01-01

This program of theoretical and experimental ground-based and low gravity research is focussed on the understanding of the dynamics and stability limits of nonaxisymmetric liquid bridges. There are three basic objectives to the proposed work: (1) to determine the stability limits of nonaxisymmetric liquid bridges held between non-coaxially aligned disks; (2) to examine the dynamics of nonaxisymmetric bridges and nonaxisymmetric oscillations of initially axisymmetric bridges (some of these experiments require a low gravity environment and the ground-based research will culminate in a definitive flight experiment); and (3) to experimentally investigate the vibration sensitivity of liquid bridges under terrestrial and low gravity conditions.

Dynamical behavior and Jacobi stability analysis of wound strings

NASA Astrophysics Data System (ADS)

Lake, Matthew J.; Harko, Tiberiu

2016-06-01

We numerically solve the equations of motion (EOM) for two models of circular cosmic string loops with windings in a simply connected internal space. Since the windings cannot be topologically stabilized, stability must be achieved (if at all) dynamically. As toy models for realistic compactifications, we consider windings on a small section of mathbb {R}^2, which is valid as an approximation to any simply connected internal manifold if the winding radius is sufficiently small, and windings on an S^2 of constant radius mathcal {R}. We then use Kosambi-Cartan-Chern (KCC) theory to analyze the Jacobi stability of the string equations and determine bounds on the physical parameters that ensure dynamical stability of the windings. We find that, for the same initial conditions, the curvature and topology of the internal space have nontrivial effects on the microscopic behavior of the string in the higher dimensions, but that the macroscopic behavior is remarkably insensitive to the details of the motion in the compact space. This suggests that higher-dimensional signatures may be extremely difficult to detect in the effective (3+1)-dimensional dynamics of strings compactified on an internal space, even if configurations with nontrivial windings persist over long time periods.

Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

PubMed

Albatsh, Fadi M; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M A

2015-01-01

This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches.

Effect of midsole thickness of dance shoes on dynamic postural stability.

PubMed

Wyon, Matthew A; Cloak, Ross; Lucas, Josephine; Clarke, Frances

2013-12-01

Landing from jumps is one of the main causes of injury within dance. A number of studies have reported a negative effect of shoe midsole thickness on lower limb kinematics during running due to the reduction in afferent sensory outputs from the foot's epithelium. The purpose of this study was to examine the influence of varying midsole thicknesses in dance shoes on dynamic postural stability during a single-leg landing. Twenty-eight female undergraduate dance participants volunteered for the study. They carried out three trials under four conditions: barefoot and in ballet flats (2 mm midsole thickness), jazz shoes (7 mm), and dance sneakers (30 mm). The task consisted of a single-leg forward jump over a hurdle at 50% of their maximal vertical jump height, landing on a force platform, and balancing for 3 seconds. The stability indices for vertical stability (VSI), anterior-posterior stability (APSI), medial-lateral stability (MLSI), and dynamic postural stability (DPSI) were calculated using Wikstrom's revised method. Significant differences were reported between the midsole thicknesses for both DPSI and VSI (p<0.01). No statistical differences were noted for the indices SPSI or MLSI. The present data agree with the running studies in that increased midsole thickness has a negative influence on landing stability.

Optimal Placement of Unified Power Flow Controllers to Improve Dynamic Voltage Stability Using Power System Variable Based Voltage Stability Indices

PubMed Central

Albatsh, Fadi M.; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M. A.

2015-01-01

This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

Systemic Air Embolism After CT-guided Lung Biopsy

ClinicalTrials.gov

2017-11-27

Patients Who Underwent Percutaneous Lung Biopsy Under CT Guidance; Patients Who Presented Systemic Air Embolism After Percutaneous Lung Biopsy Under CT Guidance Depicted at the Time of the Procedure on a Whole Thoracic CT

Dynamical stability of the one-dimensional rigid Brownian rotator: the role of the rotator’s spatial size and shape

NASA Astrophysics Data System (ADS)

Jeknić-Dugić, Jasmina; Petrović, Igor; Arsenijević, Momir; Dugić, Miroljub

2018-05-01

We investigate dynamical stability of a single propeller-like shaped molecular cogwheel modelled as the fixed-axis rigid rotator. In the realistic situations, rotation of the finite-size cogwheel is subject to the environmentally-induced Brownian-motion effect that we describe by utilizing the quantum Caldeira-Leggett master equation. Assuming the initially narrow (classical-like) standard deviations for the angle and the angular momentum of the rotator, we investigate the dynamics of the first and second moments depending on the size, i.e. on the number of blades of both the free rotator as well as of the rotator in the external harmonic field. The larger the standard deviations, the less stable (i.e. less predictable) rotation. We detect the absence of the simple and straightforward rules for utilizing the rotator’s stability. Instead, a number of the size-related criteria appear whose combinations may provide the optimal rules for the rotator dynamical stability and possibly control. In the realistic situations, the quantum-mechanical corrections, albeit individually small, may effectively prove non-negligible, and also revealing subtlety of the transition from the quantum to the classical dynamics of the rotator. As to the latter, we detect a strong size-dependence of the transition to the classical dynamics beyond the quantum decoherence process.

14 CFR 23.181 - Dynamic stability.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Dynamic stability. 23.181 Section 23.181 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... force required to maintain speeds differing from the trim speed by at least plus and minus 15 percent is...

Feasibility of Human Skin Grafts on an Isolated but Accessible Vascular Supply on Athymic Rats as a System to Study Percutaneous Penetration and Cutaneous Injury.

DTIC Science & Technology

1983-11-01

HUMAN SKIN GRAFTS ON AN ISOLATED BUT ACCESSIBLE VASCULAR SUPPLY ON ATHYMIC RATS AS A SYSTEM TO STUDY PERCUTANEOUS PENETRATION AND CUTANEOUS INJURY...RECIPIENT’S CATALOG NUMBER 4. TITLE (aend Subtitle) S. TYPE OF REPORT & PERIOD COVERED Feasibility of Human Skin Grafts on an Isolated Annual report...Human skin graft on athymic rat Human skin model to study percutaneous penetration and cutaneous injury 20. ABSTRACT (Contiue an reverse *ftb it

Percutaneous drainage of Morel-Lavallée lesions when the diagnosis is delayed.

PubMed

Zhong, Biao; Zhang, Chi; Luo, Cong-feng

2014-10-01

Morel-Lavallée lesions are a closed internal degloving, and open débridement can damage the only remaining blood supply to the skin. We performed percutaneous draining and débridement to treat 8 patients in whom the diagnosis of Morel-Lavallée lesions was delayed more than 1 week. Here we discuss our treatment procedures and the outcomes in these 8 patients. We consider percutaneous drainage to be an effective treatment for patients with delayed diagnosis of Morel-Lavallée lesions.

Enterococcus faecalis endocarditis following percutaneous manipulation of a biliary tract calculus and ERCP

PubMed Central

Ronald, Allan R; Pattullo, Andrew LS

1990-01-01

A case of Enterococcus faecalis endocarditis followed endoscopic retrograde cholangiopancreatography and percutaneous extraction of a biliary calculus is reported. The most likely cause of endocarditis, though unproven, is the latter procedure, as the bile is often infected during biliary tract obstruction, and bacteremia is frequent during percutaneous manipulations. Initial therapy with vancomycin was unsuccessful in clearing the bacteremia, possibly due to vancomycin tolerance of the isolate and lack of an aminoglycoside in the initial regimen. Cure was obtained when therapy with ampicillin and gentamicin was undertaken. PMID:22553458

Percutaneous Closure of 2 Paravalvular Leaks and a Gerbode Defect after Mitral Valve Replacement for Infective Endocarditis.

PubMed

Peñalver, Jorge; Shatila, Wassim; Silva, Guilherme V

2017-04-01

Surgical valve replacement after infective endocarditis can result in local destructive paravalvular lesions. A 30-year-old woman with infective endocarditis underwent mitral valve replacement that was complicated postoperatively by 2 paravalvular leaks. During percutaneous closure of the leaks, a Gerbode defect was also found and closed. We discuss our patient's case and its relation to others in the relevant medical literature. To our knowledge, we are the first to describe the use of a percutaneous approach to close concomitant paravalvular leaks and a Gerbode defect.

Emergency percutaneous tracheostomy in a severely burned patient with upper airway obstruction and circulatory arrest.

PubMed

Schlossmacher, Pascal; Martinet, Olivier; Testud, Richard; Agesilas, Fabrice; Benhamou, Léon; Gauzëre, Bernard Alex

2006-02-01

We report the life-saving use of Griggs percutaneous tracheostomy in an arrested patient with complex upper airway obstruction, as a result of burns, smoke injuries and iterative tracheal intubation attempts. The technique was performed blindly at bedside to treat an acute episode of failed ventilation and intubation and cardiac arrest in a patient with altered neck anatomy. The intervention salvaged the situation, leaving a definitive airway. The feasibility of using an emergency Griggs percutaneous tracheostomy versus cricothyroidotomy is suggested in selected cases.

Percutaneous closure of a large ascending aortic pseudoaneurysm.

PubMed

Nogueira, Marta Afonso; Fiarresga, António; de Sousa, Lídia; Galrinho, Ana; Santos, Ninel; Nobre, Isabel; Laranjeira, Álvaro; Cruz Ferreira, Rui

2016-02-01

Pseudoaneurysm of the ascending aorta is a rare complication, usually after thoracic surgery or trauma. Since surgical repair is associated with very high morbidity and mortality, percutaneous closure has been described as an alternative. In this regard, we present a case in which a symptomatic large pseudoaneurysm of the ascending aorta was treated percutaneously due to the high surgical risk. Despite the technical difficulties, this procedure had a good final result followed by clinical success. Copyright © 2016 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

Effect of arm swing strategy on local dynamic stability of human gait.

PubMed

Punt, Michiel; Bruijn, Sjoerd M; Wittink, Harriet; van Dieën, Jaap H

2015-02-01

Falling causes long term disability and can even lead to death. Most falls occur during gait. Therefore improving gait stability might be beneficial for people at risk of falling. Recently arm swing has been shown to influence gait stability. However at present it remains unknown which mode of arm swing creates the most stable gait. To examine how different modes of arm swing affect gait stability. Ten healthy young male subjects volunteered for this study. All subjects walked with four different arm swing instructions at seven different gait speeds. The Xsens motion capture suit was used to capture gait kinematics. Basic gait parameters, variability and stability measures were calculated. We found an increased stability in the medio-lateral direction with excessive arm swing in comparison to normal arm swing at all gait speeds. Moreover, excessive arm swing increased stability in the anterior-posterior and vertical direction at low gait speeds. Ipsilateral and inphase arm swing did not differ compared to a normal arm swing. Excessive arm swing is a promising gait manipulation to improve local dynamic stability. For excessive arm swing in the ML direction there appears to be converging evidence. The effect of excessive arm swing on more clinically relevant groups like the more fall prone elderly or stroke survivors is worth further investigating. Excessive arm swing significantly increases local dynamic stability of human gait. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparative effectiveness of lumbar stabilization, dynamic strengthening, and Pilates on chronic low back pain: randomized clinical trial.

PubMed

Bhadauria, Esha A; Gurudut, Peeyoosha

2017-08-01

The aim of the present study was to compare three different forms of exercises namely lumbar stabilization, dynamic strengthening, and Pilates on chronic low back pain (LBP) in terms of pain, range of motion, core strength and function. In this study, 44 subjects suffering from non-specific LBP for more than 3 months were randomly allocated into the lumbar stabilization group, the dynamic strengthening group, and the Pilates group. Ten sessions of exercises for 3 weeks were prescribed along with interferential current and hot moist pack. Pain was assessed by visual analog scale, functional affection by modified Oswestry Disability Questionnaire, range of motion by assessing lumbar flexion and extension by modified Schober test and core strength was assessed by pressure biofeedback on day 1 and day 10 of the treatment. There was reduction of pain, improvement in range of motion, functional ability and core strength in all the 3 exercise groups. The improvement was significantly greater in the lumbar stabilization group for all the outcome measures, when compared the posttreatment after 10th session. Pairwise comparison showed that there was greater reduction of disability in the Pilates group than the dynamic strengthening group. It was concluded that the lumbar stabilization is more superior compared to the dynamic strengthening and Pilates in chronic nonspecific LBP. However, long-term benefits need to be assessed and compared with prospective follow-up studies.

Flight dynamics and control modelling of damaged asymmetric aircraft

NASA Astrophysics Data System (ADS)

Ogunwa, T. T.; Abdullah, E. J.

2016-10-01

This research investigates the use of a Linear Quadratic Regulator (LQR) controller to assist commercial Boeing 747-200 aircraft regains its stability in the event of damage. Damages cause an aircraft to become asymmetric and in the case of damage to a fraction (33%) of its left wing or complete loss of its vertical stabilizer, the loss of stability may lead to a fatal crash. In this study, aircraft models for the two damage scenarios previously mentioned are constructed using stability derivatives. LQR controller is used as a direct adaptive control design technique for the observable and controllable system. Dynamic stability analysis is conducted in the time domain for all systems in this study.

Effect of impeller design and spacing on gas exchange in a percutaneous respiratory assist catheter.

PubMed

Jeffries, R Garrett; Frankowski, Brian J; Burgreen, Greg W; Federspiel, William J

2014-12-01

Providing partial respiratory assistance by removing carbon dioxide (CO2 ) can improve clinical outcomes in patients suffering from acute exacerbations of chronic obstructive pulmonary disease and acute respiratory distress syndrome. An intravenous respiratory assist device with a small (25 Fr) insertion diameter eliminates the complexity and potential complications associated with external blood circuitry and can be inserted by nonspecialized surgeons. The impeller percutaneous respiratory assist catheter (IPRAC) is a highly efficient CO2 removal device for percutaneous insertion to the vena cava via the right jugular or right femoral vein that utilizes an array of impellers rotating within a hollow-fiber membrane bundle to enhance gas exchange. The objective of this study was to evaluate the effects of new impeller designs and impeller spacing on gas exchange in the IPRAC using computational fluid dynamics (CFD) and in vitro deionized water gas exchange testing. A CFD gas exchange and flow model was developed to guide a progressive impeller design process. Six impeller blade geometries were designed and tested in vitro in an IPRAC device with 2- or 10-mm axial spacing and varying numbers of blades (2-5). The maximum CO2 removal efficiency (exchange per unit surface area) achieved was 573 ± 8 mL/min/m(2) (40.1 mL/min absolute). The gas exchange rate was found to be largely independent of blade design and number of blades for the impellers tested but increased significantly (5-10%) with reduced axial spacing allowing for additional shaft impellers (23 vs. 14). CFD gas exchange predictions were within 2-13% of experimental values and accurately predicted the relative improvement with impellers at 2- versus 10-mm axial spacing. The ability of CFD simulation to accurately forecast the effects of influential design parameters suggests it can be used to identify impeller traits that profoundly affect facilitated gas exchange. Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Comparison of transradial and transfemoral artery approach for percutaneous coronary angiography and angioplasty: A retrospective seven-year experience from a north Indian center

PubMed Central

Tewari, Satyendra; Sharma, Naveen; Kapoor, Aditya; Syal, Sanjeev Kumar; Kumar, Sudeep; Garg, Naveen; Goel, Pravin K.

2013-01-01

Background With the increasing prevalence of coronary artery disease, percutaneous coronary artery procedures have become even more important. Our study has compared transradial to transfemoral artery approach for coronary procedures in Indian population. Aims and objective Comparison of transradial and transfemoral artery approach for percutaneous coronary procedures. Material & methods 26,238 patients, who underwent percutaneous coronary artery procedures, were divided into two groups depending upon transradial and transfemoral artery approach and compared for the various demographic and clinical characteristics, risk factors profile, vascular access and procedural details. Results 26,238 patients underwent percutaneous coronary procedures at our center. 81% were male and 19% were female. 55.65% and 44.35% procedures were done through transfemoral and transradial approach, respectively. 17,417 (66.38%) coronary angiographies were done, out of which 53.92% were transradial and 46.08% were transfemoral procedures. 8821 (33.62%) Percutaneous Transluminal Coronary Angioplasty (PTCA) were done, out of which 25.46% and 74.54% were done through transradial and transfemoral approach, respectively. Mean fluoroscopy time was 4.40 ± 3.55 min for transradial and 3.30 ± 3.66 min for transfemoral CAG (p < 0.001). For PTCA mean fluoroscopy time was 13.53 ± 2.53 min for transradial and 12.61 ± 9.524 min for transfemoral PTCA (p < 0.001). Minor and major procedure related complications and total duration of hospital stay were lower in transradial as compared to transfemoral group. Conclusion The number of percutaneous transradial procedures have increased significantly with reduced complication rates and comparable success rate to transfemoral approach, along with the additional benefits to patient in terms of patient comfort, preference and reduced cost of health delivery. PMID:23992998

[Early complications of Griggs percutaneous tracheotomy in own material].

PubMed

Pietkiewicz, Piotr; Machała, Waldemar; Kuśmierczyk, Krzysztof; Miłoński, Jarosław; Wiśniewski, Tomasz; Urbaniak, Joanna; Olszewski, Jurek

2012-01-01

The aim of the work was to assess early complications of Griggs percutaneous tracheotomy in the own material. The study covered 155 patients aged 17-88, including 36 women and 119 men. The patients were treated at the Department of Anaesthesiology and Intensive Therapy between 2006-2010. They underwent Griggs percutaneous tracheostomy by a laryngologist or a trained anaesthesiologist. Each surgical procedure was conducted with the use of Portex Blue Line Ultra Percutaneous Tracheotomy Kit (Smiths Medical Co., USA), the trachea was intubated while the patient was under general anaesthesia with propofol, fentanyl and relaxation with atracurium. The studied material revealed Griggs percutaneous tracheotomy complications in 26 patients (16.8%), in which 11 patients (7.1%) presented complications within the perioperative period while 15 patients (9.7%) reported early complications. Haemorrhage, usually not very profuse, occurred 7 times (4.6%), mainly in tracheopunction, and was the most often perioperative complication. Moreover, in the perioperative period, 3 patients (1.9%) had trachea identifications difficulties, which required tracheopunction many a time, and 1 patient (0.65%) encountered sudden circulatory arrest with asystolia and effective CPR. In the early postoperative period after Griggs percutaneous tracheotomy, the most common complication was haemorrhage in the operative twenty-four hours, which was noted in 10 patients (6.5%). Among other adverse complications were found: infection of the tissues near the tracheostomal region in 3 patients (1.9%), subcutaneous oedema in 1 patient (0.65%), accidental removing the tube from an unformed tracheostoma in 1 patient (0.65%). In the studied material, complications after Griggs percutaneous tracheotomy amounted to 16.8%, of which 7.1% occurred in the perioperative period while 9.7% were early complications, mainly light bleeding. This may prove good preparation of the surgical team for the surgical procedures. Copyright © 2012 Polish Otolaryngology Society. Published by Elsevier Urban & Partner Sp. z.o.o. All rights reserved.

Improved split renal function after percutaneous nephrostomy in young adults with severe hydronephrosis due to ureteropelvic junction obstruction.

PubMed

Zhang, Shiwei; Zhang, Qing; Ji, Changwei; Zhao, Xiaozhi; Liu, Guangxiang; Zhang, Shun; Li, Xiaogong; Lian, Huibo; Zhang, Gutian; Guo, Hongqian

2015-01-01

We evaluated percutaneous nephrostomy for adult kidneys with severe hydronephrosis due to ureteropelvic junction obstruction and less than 10% split renal function. In this retrospective analysis we included patients who underwent percutaneous nephrostomy for unilateral ureteropelvic junction obstruction of the kidneys with hydronephrosis and less than 10% split renal function at our hospital between May 2009 and January 2012. Adults (age 18 years or greater) were divided into those 35 years or younger (young adults) and older than 35 years (older adults). The percutaneous nephrostomy remained in situ a mean ± SD of 6.62 ± 2.55 weeks and patients underwent repeat renography before pyeloplasty. When there was no significant improvement in split renal function (10% or greater) and drainage (greater than 400 ml per day), nephrectomy was performed. Otherwise pyeloplasty was performed. Patients were followed by renography, ultrasound and contrast computerized tomography at 3 and 6 months, at 1 year and annually thereafter. Of 53 patients 30 (56.6%) showed improvement after percutaneous nephrostomy drainage and urine output greater than 400 ml per day with percutaneous nephrostomy. Pyeloplasty was then performed. Of 29 young adults 24 (82.8%) showed improved split renal function vs 6 of 24 older adults (25%). Nephrectomy of the other 23 kidneys was performed. At a mean followup of 19.27 ± 7.82 months (range 12 to 36), no patient showed hypertension or urinary tract infection. Split renal function detected by renography may not accurately predict recovered, poorly functioning kidneys, especially in young adults. First observing the recoverability of hydronephrotic kidneys by percutaneous nephrostomy drainage and then preserving select kidneys may be an effective method to manage poorly functioning kidneys due to ureteropelvic junction obstruction. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Evaluation of surgical strategy of conventional vs. percutaneous robot-assisted spinal trans-pedicular instrumentation in spondylodiscitis.

PubMed

Keric, Naureen; Eum, David J; Afghanyar, Feroz; Rachwal-Czyzewicz, Izabela; Renovanz, Mirjam; Conrad, Jens; Wesp, Dominik M A; Kantelhardt, Sven R; Giese, Alf

2017-03-01

Robot-assisted percutaneous insertion of pedicle screws is a recent technique demonstrating high accuracy. The optimal treatment for spondylodiscitis is still a matter of debate. We performed a retrospective cohort study on surgical patients treated with pedicle screw/rod placement alone without the application of intervertebral cages. In this collective, we compare conventional open to a further minimalized percutaneous robot-assisted spinal instrumentation, avoiding a direct contact of implants and infectious focus. 90 records and CT scans of patients treated by dorsal transpedicular instrumentation of the infected segments with and without decompression and antibiotic therapy were analysed for clinical and radiological outcome parameters. 24 patients were treated by free-hand fluoroscopy-guided surgery (121 screws), and 66 patients were treated by percutaneous robot-assisted spinal instrumentation (341 screws). Accurate screw placement was confirmed in 90 % of robot-assisted and 73.5 % of free-hand placed screws. Implant revision due to misplacement was necessary in 4.95 % of the free-hand group compared to 0.58 % in the robot-assisted group. The average intraoperative X-ray exposure per case was 0.94 ± 1.04 min in the free-hand group vs. 0.4 ± 0.16 min in the percutaneous group (p = 0.000). Intraoperative adverse events were observed in 12.5 % of free-hand placed pedicle screws and 6.1 % of robot robot-assisted screws. The mean postoperative hospital stay in the free-hand group was 18.1 ± 12.9 days, and in percutaneous group, 13.8 ± 5.6 days (p = 0.012). This study demonstrates that the robot-guided insertion of pedicle screws is a safe and effective procedure in lumbar and thoracic spondylodiscitis with higher accuracy of implant placement, lower radiation dose, and decreased complication rates. Percutaneous spinal dorsal instrumentation seems to be sufficient to treat lumbar and thoracic spondylodiscitis.

Local Dynamic Stability Assessment of Motion Impaired Elderly Using Electronic Textile Pants.

PubMed

Liu, Jian; Lockhart, Thurmon E; Jones, Mark; Martin, Tom

2008-10-01

A clear association has been demonstrated between gait stability and falls in the elderly. Integration of wearable computing and human dynamic stability measures into home automation systems may help differentiate fall-prone individuals in a residential environment. The objective of the current study was to evaluate the capability of a pair of electronic textile (e-textile) pants system to assess local dynamic stability and to differentiate motion-impaired elderly from their healthy counterparts. A pair of e-textile pants comprised of numerous e-TAGs at locations corresponding to lower extremity joints was developed to collect acceleration, angular velocity and piezoelectric data. Four motion-impaired elderly together with nine healthy individuals (both young and old) participated in treadmill walking with a motion capture system simultaneously collecting kinematic data. Local dynamic stability, characterized by maximum Lyapunov exponent, was computed based on vertical acceleration and angular velocity at lower extremity joints for the measurements from both e-textile and motion capture systems. Results indicated that the motion-impaired elderly had significantly higher maximum Lyapunov exponents (computed from vertical acceleration data) than healthy individuals at the right ankle and hip joints. In addition, maximum Lyapunov exponents assessed by the motion capture system were found to be significantly higher than those assessed by the e-textile system. Despite the difference between these measurement techniques, attaching accelerometers at the ankle and hip joints was shown to be an effective sensor configuration. It was concluded that the e-textile pants system, via dynamic stability assessment, has the potential to identify motion-impaired elderly.

Workshop on Dynamics and Aeroelastic Stability Modeling of Rotorcraft Systems (3rd), Held in Durham, North Carolina on March 12-14, 1990

DTIC Science & Technology

1990-03-14

aeroelastic stability studies of composite rotor blades in hover, Panda and Chopra [481 also stu-died the aeroelastic stability and response of hingeless...31, No. 4, pp. 29-35. 1986.I48 Panda , B. and Chopra. I., "Dynamics of Composite Rotor Blades in Forward Flight," Vertica, Vol. 11, No. 1/2,pp. 187-209...conditions. References [1] Panda ,B., Chopra,I., "Flap-Lag-Torsion Stability in Forward Flight", Journal of the American Helicopter Society, 30, No. 4, Oct

A decentralised multi-agent approach to enhance the stability of smart microgrids with renewable energy

NASA Astrophysics Data System (ADS)

Rahman, M. S.; Pota, H. R.; Mahmud, M. A.; Hossain, M. J.

2016-05-01

This paper presents the impact of large penetration of wind power on the transient stability through a dynamic evaluation of the critical clearing times (CCTs) by using intelligent agent-based approach. A decentralised multi-agent-based framework is developed, where agents represent a number of physical device models to form a complex infrastructure for computation and communication. They enable the dynamic flow of information and energy for the interaction between the physical processes and their activities. These agents dynamically adapt online measurements and use the CCT information for relay coordination to improve the transient stability of power systems. Simulations are carried out on a smart microgrid system for faults at increasing wind power penetration levels and the improvement in transient stability using the proposed agent-based framework is demonstrated.

Influence of point defects and impurities on the dynamical stability of δ-plutonium

NASA Astrophysics Data System (ADS)

Dorado, B.; Bieder, J.; Torrent, M.

2017-06-01

We use first-principles calculations to provide direct evidence of the effect of aluminum, gallium, iron and uranium on the dynamical stability of δ-plutonium. We first show that the δ phase is dynamically unstable at low temperature, as seen in experiments, and that this stability directly depends on the plutonium 5f orbital occupancies. Then, we demonstrate that both aluminum and gallium stabilize the δ phase, contrary to iron. As for uranium, which is created during self-irradiation and whose effect on plutonium has yet to be understood, we show that it leaves a few unstable vibrational modes and that higher concentrations lead to an almost complete stabilization. Finally, we provide an attempt at a consistent analysis of the experimental Pu-Ga phonon density of states. We show that the presence of gallium can reproduce only partially the experimental measurements, and we investigate how point defects, such as interstitials and vacancies, affect the calculated phonon density of states.

Influence of point defects and impurities on the dynamical stability of δ-plutonium.

PubMed

Dorado, B; Bieder, J; Torrent, M

2017-06-21

We use first-principles calculations to provide direct evidence of the effect of aluminum, gallium, iron and uranium on the dynamical stability of δ-plutonium. We first show that the δ phase is dynamically unstable at low temperature, as seen in experiments, and that this stability directly depends on the plutonium 5f orbital occupancies. Then, we demonstrate that both aluminum and gallium stabilize the δ phase, contrary to iron. As for uranium, which is created during self-irradiation and whose effect on plutonium has yet to be understood, we show that it leaves a few unstable vibrational modes and that higher concentrations lead to an almost complete stabilization. Finally, we provide an attempt at a consistent analysis of the experimental Pu-Ga phonon density of states. We show that the presence of gallium can reproduce only partially the experimental measurements, and we investigate how point defects, such as interstitials and vacancies, affect the calculated phonon density of states.

The Rubber Stopper: A Simple and Inexpensive Technique to Prevent Pin Tract Infection following Kirschner Wiring of Supracondylar Fractures of Humerus in Children.

PubMed

Santy, J E; Kamal, J; Abdul-Rashid, A H; Ibrahim, S

2015-07-01

Percutaneous pinning after closed reduction is commonly used to treat supracondylar fractures of the humerus in children. Minor pin tract infections frequently occur. The aim of this study was to prevent pin tract infections using a rubber stopper to reduce irritation of the skin against the Kirschner (K) wire following percutaneous pinning. Between July 2011 and June 2012, seventeen children with closed supracondylar fracture of the humerus of Gartland types 2 and 3 were treated with this technique. All patients were treated with closed reduction and percutaneous pinning and followed up prospectively. Only one patient, who was a hyperactive child, developed pin tract infection due to softening of the plaster slab. We found using the rubber stopper to be a simple and inexpensive method to reduce pin tract infections following percutaneous pinning.

The Rubber Stopper: A Simple and Inexpensive Technique to Prevent Pin Tract Infection following Kirschner Wiring of Supracondylar Fractures of Humerus in Children

PubMed Central

Santy, JE; Abdul-Rashid, AH; Ibrahim, S

2015-01-01

Percutaneous pinning after closed reduction is commonly used to treat supracondylar fractures of the humerus in children. Minor pin tract infections frequently occur. The aim of this study was to prevent pin tract infections using a rubber stopper to reduce irritation of the skin against the Kirschner (K) wire following percutaneous pinning. Between July 2011 and June 2012, seventeen children with closed supracondylar fracture of the humerus of Gartland types 2 and 3 were treated with this technique. All patients were treated with closed reduction and percutaneous pinning and followed up prospectively. Only one patient, who was a hyperactive child, developed pin tract infection due to softening of the plaster slab. We found using the rubber stopper to be a simple and inexpensive method to reduce pin tract infections following percutaneous pinning. PMID:28435603

Morel-Lavallée lesion: diagnosis and treatment with imaging techniques.

PubMed

Martel Villagrán, J; Díaz Candamio, M J; Bueno Horcajadas, A

We aim to review the characteristics of Morel-Lavallée lesions and to evaluate their treatment. We retrospectively reviewed 17 patients (11 men and 6 women; mean age, 56.1 years, range 25-81 years) diagnosed with Morel-Lavallée lesions in two different departments. All patients underwent ultrasonography, 5 underwent computed tomography, and 9 underwent magnetic resonance imaging. Percutaneous treatment with fine-needle aspiration and/or drainage with a 6F-8F catheter was performed in 13 patients. Two patients required percutaneous sclerosis with doxycycline. All patients responded adequately to percutaneous treatment, although it was necessary to repeat the procedure in 4 patients. Radiologists need to be familiar with this lesion that can be treated percutaneously in the ultrasonography suite when it is not associated with other entities. Copyright © 2018 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

[Gastrocolic fistula as a complication of percutaneous feeding gastrostomy, description of three cases and review of the literature].

PubMed

Jiménez Varo, Ignacio; Gros Herguido, Noelia; Parejo Campos, Juana; Tatay Domínguez, Dolores; Pereira Cunill, José Luis; Serrano Aguayo, Pilar; Socas Macías, María; García-Luna, Pedro Pablo

2014-02-01

Percutaneous gastrostomy, is the procedure of choice to provide enteral access in patients requiring nutritional support in this way in the long run, relegating the surgical gastrostomy. We present three patients requiring percutaneous gastrostomy for nutritional support. In two cases was performed endoscopic gastrostomy and another one using interventional radiology. While performing percutaneous gastrostomy clinical incidents were not detected, but when trying the replacement of gastrostomy tubes, showed the presence of gastrocolic fistula that caused failure or turnover in one case, or abdominal pain and diarrhea in the two other cases. Despite being a safe technique, should be done a proper patient selection in order to minimize the potential complications that may occur, as gastrocolic fistula, recommending in doubtful cases test of image such CT (computerized Tomography). Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Percutaneous endoscopic intra-annular subligamentous herniotomy for large central disc herniation: a technical case report.

PubMed

Lee, Sang-Ho; Choi, Kyung-Chul; Baek, Oon Ki; Kim, Ho Jin; Yoo, Seung-Hwa

2014-04-01

Technical case report. To describe the novel technique of percutaneous endoscopic herniotomy using a unilateral intra-annular subligamentous approach for the treatment of large centrally herniated discs. Open discectomy for large central disc herniations may have poor long-term prognosis due to heavy loss of intervertebral disc tissue, segmental instability, and recurrence of pain. Six consecutive patients who presented with back and leg pain, and/or weakness due to a large central disc herniation were treated using percutaneous endoscopic herniotomy with a unilateral intra-annular subligamentous approach. The patients experienced relief of symptoms and intervertebral disc spaces were well maintained. The annular defects were noted to be in the process of healing and recovery. Percutaneous endoscopic unilateral intra-annular subligamentous herniotomy was an effective and affordable minimally invasive procedure for patients with large central disc herniations, allowing preservation of nonpathological intradiscal tissue through a concentric outer-layer annular approach.

[Intramedullary nailing in diaphyseal clavicle fractures using minimally invasive percutaneous reduction].

PubMed

Müller, M; Freude, T; Stöckle, U; Kraus, T M

2017-02-01

Closed reduction and intramedullary nailing is common in diaphyseal clavicle fractures. The aim of this report is to demonstrate a surgical method with minimally invasive percutaneous reduction in cases where closed reduction fails. The procedure is associated with good cosmetic results. Percutaneous reduction using two reduction forceps enables intramedullary nailing without an open procedure. Open, multifragmented or non-dislocated fractures, oblique fractures due to postoperative dislocation or shortening risk, fracture having potential to become compound fractures, neurovascular complications, pseudoarthroses. The patient is in beach-chair position. After an incision, the nail is entered from medial, two reduction forceps are mounted percutaneously at the lateral and medial fragment. After reduction the nail is pushed forward into the lateral fragment. Thereby, the fracture hematoma is not disturbed for the most part. Early functional rehabilitation with maximal abduction and anteversion of 90° for 6 weeks. Anatomic reduction can be achieved with mild cosmetic impairment.

Percutaneous dilatational tracheostomy following total artificial heart implantation.

PubMed

Spiliopoulos, Sotirios; Dimitriou, Alexandros Merkourios; Serrano, Maria Rosario; Guersoy, Dilek; Autschbach, Ruediger; Goetzenich, Andreas; Koerfer, Reiner; Tenderich, Gero

2015-07-01

Coagulation disorders and an immune-altered state are common among total artificial heart patients. In this context, we sought to evaluate the safety of percutaneous dilatational tracheostomy in cases of prolonged need for mechanical ventilatory support. We retrospectively analysed the charts of 11 total artificial heart patients who received percutaneous dilatational tracheostomy. We focused on early and late complications. We observed no major complications and no procedure-related deaths. Early minor complications included venous oozing (45.4%) and one case of local infection. Late complications, including subglottic stenosis, stomal infection or infections of the lower respiratory tract, were not observed. In conclusion, percutaneous dilatational tracheostomy in total artificial heart patients is safe. Considering the well-known benefits of early tracheotomy over prolonged translaryngeal intubation, we advocate early timing of therapy in cases of prolonged mechanical ventilation. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Percutaneous fiber optic angioscopy of the left ventricle in patients with rheumatic valvular disease

NASA Astrophysics Data System (ADS)

Hirose, Junichi; Oshima, Tomomitsu; Fujimori, Yoshiharu; Uchida, Yasumi

1993-05-01

Recent advances in fiberoptic technology enabled us to observe percutaneously the cardiac chambers and valves. We examined left ventricular luminal and valvular changes by percutaneous fiberoptic angioscopy in patients with rheumatic valvular disease. Six patients with echocardiographic rheumatic changes in the mitral valves, underwent angioscopy during routine cardiac catheterization. The fiberscope 4.2 F in diameter, and the guiding catheter 9 F in external diameter with an inflatable balloon around the distal most tip were used for angioscopy. The left ventricular endocardial surface was diffusely white in color or white and brown in mosaic fashion. Echocardiography and angiography had low sensitivity for detecting the changes of the left ventricular luminal surface. Whitish changes which were observed by angioscopy were not related to the indices derived from echocardiography and angiography. The results indicate the possibility of percutaneous angioscopy in detecting left ventricular luminal changes in patients with rheumatic valvular disease.

Constrained dynamics approach for motion synchronization and consensus

NASA Astrophysics Data System (ADS)

Bhatia, Divya

In this research we propose to develop constrained dynamical systems based stable attitude synchronization, consensus and tracking (SCT) control laws for the formation of rigid bodies. The generalized constrained dynamics Equations of Motion (EOM) are developed utilizing constraint potential energy functions that enforce communication constraints. Euler-Lagrange equations are employed to develop the non-linear constrained dynamics of multiple vehicle systems. The constraint potential energy is synthesized based on a graph theoretic formulation of the vehicle-vehicle communication. Constraint stabilization is achieved via Baumgarte's method. The performance of these constrained dynamics based formations is evaluated for bounded control authority. The above method has been applied to various cases and the results have been obtained using MATLAB simulations showing stability, synchronization, consensus and tracking of formations. The first case corresponds to an N-pendulum formation without external disturbances, in which the springs and the dampers connected between the pendulums act as the communication constraints. The damper helps in stabilizing the system by damping the motion whereas the spring acts as a communication link relaying relative position information between two connected pendulums. Lyapunov stabilization (energy based stabilization) technique is employed to depict the attitude stabilization and boundedness. Various scenarios involving different values of springs and dampers are simulated and studied. Motivated by the first case study, we study the formation of N 2-link robotic manipulators. The governing EOM for this system is derived using Euler-Lagrange equations. A generalized set of communication constraints are developed for this system using graph theory. The constraints are stabilized using Baumgarte's techniques. The attitude SCT is established for this system and the results are shown for the special case of three 2-link robotic manipulators. These methods are then applied to the formation of N-spacecraft. Modified Rodrigues Parameters (MRP) are used for attitude representation of the spacecraft because of their advantage of being a minimum parameter representation. Constrained non-linear equations of motion for this system are developed and stabilized using a Proportional-Derivative (PD) controller derived based on Baumgarte's method. A system of 3 spacecraft is simulated and the results for SCT are shown and analyzed. Another problem studied in this research is that of maintaining SCT under unknown external disturbances. We use an adaptive control algorithm to derive control laws for the actuator torques and develop an estimation law for the unknown disturbance parameters to achieve SCT. The estimate of the disturbance is added as a feed forward term in the actual control law to obtain the stabilization of a 3-spacecraft formation. The disturbance estimates are generated via a Lyapunov analysis of the closed loop system. In summary, the constrained dynamics method shows a lot of potential in formation control, achieving stabilization, synchronization, consensus and tracking of a set of dynamical systems.

Vesicle Stability and Dynamics: An Undergraduate Biochemistry Laboratory

ERIC Educational Resources Information Center

Del Bianco, Cristina; Torino, Domenica; Mansy, Sheref S.

2014-01-01

A laboratory exercise is described that helps students learn about lipid self-assembly by making vesicles under different solution conditions. Concepts covering the chemical properties of different lipids, the dynamics of lipids, and vesicle stability are explored. Further, the described protocol is easy and cheap to implement. One to two…

Cognition as a Dynamic System: Principles from Embodiment

ERIC Educational Resources Information Center

Smith, Linda B.

2005-01-01

Traditional approaches to cognitive development concentrate on the stability of cognition and explain that stability via concepts segregated from perceiving acting. A dynamic systems approach in contrast focuses on the self-organization of behavior in tasks. This article uses recent results concerning the embodiment of cognition to argue for a…

Advances in Turbulent Combustion Dynamics Simulations in Bluff-Body Stabilized Flames-Body Stabilized Flames

DTIC Science & Technology

2015-11-30

Master’s Thesis 3. DATES COVERED (From - To) 01 Nov 2015 – 30 Nov 2015 4. TITLE AND SUBTITLE Advances in Turbulent Combustion Dynamics Simulations...the three main aspects of bluff-body stabilized flames: stationary combustion , lean blow-out, and thermo-acoustic instabilities. For the cases of...stationary combustion and lean blow-out, an improved version of the Linear Eddy Model approach is used, while in the case of thermo-acoustic

Robust Stability and Control of Multi-Body Ground Vehicles with Uncertain Dynamics and Failures

DTIC Science & Technology

2010-01-01

and N. Zhang, 2008. “Robust stability control of vehicle rollover subject to actuator time delay”. Proc. IMechE Part I: J. of systems and control ...Dynamic Systems and Control Conference, Boston, MA, Sept 2010 R.K. Yedavalli,”Robust Stability of Linear Interval Parameter Matrix Family Problem...for control coupled output regulation for a class of systems is presented. In section 2.1.7, the control design algorithm developed in section

Gravity Wave Dynamics in a Mesospheric Inversion Layer: 1. Reflection, Trapping, and Instability Dynamics

PubMed Central

Laughman, Brian; Wang, Ling; Lund, Thomas S.; Collins, Richard L.

2018-01-01

Abstract An anelastic numerical model is employed to explore the dynamics of gravity waves (GWs) encountering a mesosphere inversion layer (MIL) having a moderate static stability enhancement and a layer of weaker static stability above. Instabilities occur within the MIL when the GW amplitude approaches that required for GW breaking due to compression of the vertical wavelength accompanying the increasing static stability. Thus, MILs can cause large‐amplitude GWs to yield instabilities and turbulence below the altitude where they would otherwise arise. Smaller‐amplitude GWs encountering a MIL do not lead to instability and turbulence but do exhibit partial reflection and transmission, and the transmission is a smaller fraction of the incident GW when instabilities and turbulence arise within the MIL. Additionally, greater GW transmission occurs for weaker MILs and for GWs having larger vertical wavelengths relative to the MIL depth and for lower GW intrinsic frequencies. These results imply similar dynamics for inversions due to other sources, including the tropopause inversion layer, the high stability capping the polar summer mesopause, and lower frequency GWs or tides having sufficient amplitudes to yield significant variations in stability at large and small vertical scales. MILs also imply much stronger reflections and less coherent GW propagation in environments having significant fine structure in the stability and velocity fields than in environments that are smoothly varying. PMID:29576994

Gravity Wave Dynamics in a Mesospheric Inversion Layer: 1. Reflection, Trapping, and Instability Dynamics

NASA Astrophysics Data System (ADS)

Fritts, David C.; Laughman, Brian; Wang, Ling; Lund, Thomas S.; Collins, Richard L.

2018-01-01

An anelastic numerical model is employed to explore the dynamics of gravity waves (GWs) encountering a mesosphere inversion layer (MIL) having a moderate static stability enhancement and a layer of weaker static stability above. Instabilities occur within the MIL when the GW amplitude approaches that required for GW breaking due to compression of the vertical wavelength accompanying the increasing static stability. Thus, MILs can cause large-amplitude GWs to yield instabilities and turbulence below the altitude where they would otherwise arise. Smaller-amplitude GWs encountering a MIL do not lead to instability and turbulence but do exhibit partial reflection and transmission, and the transmission is a smaller fraction of the incident GW when instabilities and turbulence arise within the MIL. Additionally, greater GW transmission occurs for weaker MILs and for GWs having larger vertical wavelengths relative to the MIL depth and for lower GW intrinsic frequencies. These results imply similar dynamics for inversions due to other sources, including the tropopause inversion layer, the high stability capping the polar summer mesopause, and lower frequency GWs or tides having sufficient amplitudes to yield significant variations in stability at large and small vertical scales. MILs also imply much stronger reflections and less coherent GW propagation in environments having significant fine structure in the stability and velocity fields than in environments that are smoothly varying.

Open versus percutaneous repair in the treatment of acute Achilles tendon rupture: a randomized prospective study.

PubMed

Gigante, A; Moschini, A; Verdenelli, A; Del Torto, M; Ulisse, S; de Palma, L

2008-02-01

There is no agreement on the ideal type of surgical management for Achilles tendon rupture. The present randomized prospective study was performed to compare outcome data of open and percutaneous repair in the treatment of Achilles tendon rupture. Forty consecutive patients with acute rupture of Achilles tendon were recruited. Patients were randomized to receive open (group A) or percutaneous repair with Tenolig (group B). All patients followed the same rehabilitation protocol except for slight differences in the duration of immobilization. Follow-up included objective evaluation (at 4 and 12 months), subjective evaluation using the SF-12 questionnaire (at 24 months), and bilateral ultrasound scanning and isokinetic testing (at 12 months). The differences in the parameters evaluated clinically were not significant except for ankle circumference, which was significantly greater in group B. There were two minor complications in the open repair group and one case of failed repair in the percutaneous group. SF-12 questionnaire, ultrasound and isokinetic test data did not show significant differences between the groups. The present study demonstrates that the open and the percutaneous technique are both safe and effective in repairing the ruptured Achilles tendon and that both afford the same degree of restoration of clinical, ultrasound and isokinetic patterns. Medium-term results were substantially comparable. Percutaneous repair is performed on a day-surgery basis, it reduces cutaneous complications and operation times, and enables faster recovery, enhancing overall patient compliance. To us, these characteristics make it preferable to open repair in managing subcutaneous ruptures of Achilles tendon in non-professional sports practicing adults.

Temporary placement of retrievable fully covered metallic stents versus percutaneous balloon dilation in the treatment of benign biliary strictures.

PubMed

Kim, Jin Hyoung; Gwon, Dong Il; Ko, Gi-Young; Sung, Kyu-Bo; Lee, Sung Koo; Yoon, Hyun-Ki; Shin, Ji Hoon; Song, Ho-Young

2011-06-01

To compare retrospectively percutaneous transhepatic primary placement of a retrievable self-expanding metallic stent with percutaneous balloon dilation for the treatment of benign biliary strictures. From 2005-2009, 66 patients with benign biliary strictures in whom an endoscopic approach failed or in whom such an approach was inaccessible were evaluated. Of 66 patients, 31 underwent balloon dilation, and 35 underwent temporary metallic stent placement. The etiologies of the benign strictures were anastomotic stricture after surgery (n = 54), stricture secondary to intraoperative injury (n = 9), inflammatory stricture (n = 2), and stricture secondary to trauma (n = 1). The primary patency rates were significantly better in the stent group (87% at 3 years) than in the balloon group (44% at 3 years; P = .022). The indwelling period of percutaneous transhepatic biliary drainage (PTBD) catheters after the initial procedure was able to be significantly reduced in the stent group (median 2.5 months) compared with the balloon group (median 4.5 months; P = .001). Significant bleeding (associated with PTBD) occurred in one patient in the balloon group. In the stent group, stent migration occurred in two patients, and one patient underwent surgery for stent removal after failure of removal under fluoroscopic guidance. Percutaneous primary placement of a retrievable self-expanding metallic stent showed superior intermediate-term results compared with percutaneous balloon dilation for the treatment of benign biliary strictures. In addition, the indwelling period of PTBD catheters can be significantly reduced using temporary stent placement. Copyright © 2011 SIR. Published by Elsevier Inc. All rights reserved.

Percutaneous intraductal radiofrequency ablation for treatment of biliary stent occlusion: A preliminary result.

PubMed

Xia, Ning; Gong, Ju; Lu, Jian; Chen, Zhi-Jin; Zhang, Li-Yun; Wang, Zhong-Min

2017-03-14

To assess the feasibility and effectiveness of a novel application of percutaneous intraductal radiofrequency (RF) for the treatment of biliary stent obstruction. We specifically report a retrospective study presenting the results of percutaneous intraductal RF in patients with biliary stent occlusion. A total of 43 cases involving biliary stent obstruction were treated by placing an EndoHPB catheter and percutaneous intraductal RF was performed to clean stents. The stent patency was evaluated by cholangiography and follow-up by contrast enhanced computed tomography or ultrasound after the removal of the drainage catheter. Following the procedures, of the 43 patients, 40 survived and 3 died with a median survival of 80.5 (range: 30-243) d. One patient was lost to follow-up. One patient had the stent patent at the time of last follow-up. Two patients with stent blockage at 35 d and 44 d after procedure underwent percutaneous transhepatic drain insertion only. The levels of bilirubin before and after the procedure were 128 ± 65 μmol/L and 63 ± 29 μmol/L, respectively. There were no related complications (haemorrhage, bile duct perforation, bile leak or pancreatitis) and all patients' stent patency was confirmed by cholangiography after the procedure, with a median patency time of 107 (range: 12-180) d. This preliminary clinical study demonstrated that percutaneous intraductal RF is safe and effective for the treatment of biliary stent obstruction, increasing the duration of stent patency, although randomized controlled trials are needed to confirm the effectiveness of this approach.

Ultrasound-guided, percutaneous peripheral nerve stimulation: technical note.

PubMed

Chan, Isaac; Brown, Anthony R; Park, Kenneth; Winfree, Christopher J

2010-09-01

Peripheral nerve stimulation is a form of neuromodulation that applies electric current to peripheral nerves to induce stimulation paresthesias within the painful areas. To report a method of ultrasound-guided, percutaneous peripheral nerve stimulation. This technique utilizes real-time imaging to avoid injury to adjacent vascular structures during minimally invasive placement of peripheral nerve stimulator electrodes. We describe a patient that presented with chronic, bilateral foot pain following multiple foot surgeries, for whom a comprehensive, pain management treatment strategy had failed. We utilized ultrasound-guided, percutaneous tibial nerve stimulation at a thigh level to provide durable pain relief on the right side, and open peripheral nerve stimulation on the left. The patient experienced appropriate stimulation paresthesias and excellent pain relief on the plantar aspect of the right foot with the percutaneous electrode. On the left side, we were unable to direct the stimulation paresthesias to the sole of the foot, despite multiple electrode repositionings. A subsequent, open placement of a left tibial nerve stimulator was performed. This revealed that the correct electrode position against the tibial nerve was immediately adjacent to the popliteal artery, and was thus not appropriate for percutaneous placement. We describe a method of ultrasound-guided peripheral nerve stimulation that avoids the invasiveness of electrode placement via an open procedure while providing excellent pain relief. We further describe limitations of the percutaneous approach when navigating close to large blood vessels, a situation more appropriately managed with open peripheral nerve stimulator placement. Ultrasound-guided placement may be considered for patients receiving peripheral nerve stimulators placed within the deep tissues, and not easily placed in a blind fashion.

The role of CT-guided percutaneous drainage of loculated air collections: an institutional experience.

PubMed

Patel, Bhavik N; Morgan, Madeline; Tyler, Douglas; Paulson, Erik; Jaffe, Tracy A

2015-10-01

The purpose of this study is to describe our experience with the role of CT-guided percutaneous drainage of loculated intra-abdominal collections consisting entirely of gas. An IRB-approved retrospective study analyzing patients with air-only intra-abdominal collections over an 8-year period was undertaken. Seven patients referred for percutaneous drainage were included. Size of collections, subsequent development of fluid, and microbiological yield were determined. Clinical outcome was also analyzed. Out of 2835 patients referred for percutaneous drainage between 2004 and 2012, seven patients (5M, 2F; average age 63, range 54-85) met criteria for inclusion with CT showing air-only collections. Percutaneous drain placement (five 8 Fr, one 10 Fr, and one 12 Fr) using Seldinger technique was performed. Four patients (57%) had recently undergone surgery (2 Whipple, 1 colectomy, 1 hepatic resection) while two (29%) had a remote surgery (1 abdominoperineal resection, 1 sigmoidectomy). Despite the lack of detectable fluid on the original CT, 6 patients (86%) had air and fluid aspirated at drainage, 5 (83%) of the aspirates developed positive microbacterial cultures. Four patients (57%) presented with fever at the time of the initial scan, all of whom had positive cultures from aspirated fluid. Four patients (57%) had leukocytosis, all of whom had positive cultures from aspirated fluid. Although relatively rare in occurrence, patients with air-only intra-abdominal collections with signs of infection should be considered for percutaneous management similar to that of conventional infected fluid collections. Although fluid is not visible on CT, these collections can produce fluid that contains organisms.

Diagnosing regenerative nodular hyperplasia, the "great masquerader" of liver tumors.

PubMed

Foster, Jason M; Litwin, Alan; Gibbs, John F; Intengen, Marilyn; Kuvshinoff, Boris W

2006-05-01

Distinguishing benign tumors and pseudotumors of the liver from malignant tumors is a common clinical problem. Regenerative nodular hyperplasia (RNH) represents one of the more challenging pseudotumors to diagnose, because they can appear clinically indistinguishable from either a primary or a secondary liver malignancy. Even after comprehensive radiologic evaluation and image-guided percutaneous biopsy, the diagnosis of RNH can remain elusive. We reviewed the pathophysiology of RNH and present five cases illustrating the limitations of percutaneous biopsy and the utility of laparoscopic wedge biopsy in establishing the diagnosis. All patients underwent a complete workup that included percutaneous biopsy. Patients with a nondiagnostic percutaneous biopsy underwent a laparoscopic wedge biopsy or anatomical resection. H&E, vimentin, trichrome, and reticulin staining as well as CD34 immunostaining were performed. Five patients were diagnosed with RNH between May 2002 and April 2004. Three had focal nodular disease, whereas the other two had a diffuse multinodular presentation. Percutaneous biopsy definitively made the diagnosis in only one out of the five cases. Laparoscopic wedge biopsy was necessary to accurately make the diagnosis in three cases, whereas the fifth diagnosis was established after an anatomical resection. RNH is a unique pseudotumor of the liver that can present either as a solitary nodule or as a multinodular process. Percutaneous biopsy is associated with limitations in diagnosing RNH, and a more definitive surgical biopsy may be required. When RNH is considered, laparoscopic wedge biopsy is a safe and efficient way to obtain enough tissue to preserve the hepatic architecture required for diagnosis, while avoiding the morbidity of an unnecessary open resection.

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

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

Kroepil, Patric; Lanzman, Rotem S., E-mail: rotemshlomo@yahoo.de; Miese, Falk R.

2011-04-15

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

Clinical outcomes of percutaneous drainage of breast fluid collections following mastectomy with expander-based breast reconstruction

PubMed Central

2015-01-01

PURPOSE To determine clinical outcomes of patients who underwent imaging-guided percutaneous drainage of breast fluid collections following mastectomy and breast reconstruction. MATERIAL AND METHODS Retrospective review included all consecutive patients who underwent percutaneous drainage of fluid collections following mastectomy with tissue expander-based reconstruction between January 2007 and September 2012. A total of 879 mastectomies (563 patients) with expander-based breast reconstruction were performed during this period. 28 patients (5%) developed fluid collections, which led to 30 imaging-guided percutaneous drainage procedures. The median follow up time was 533 days. Patient characteristics, surgical technique, microbiology analysis, and clinical outcomes were reviewed. RESULTS The mean age was 51.5 years (range 30.9 to 69.4 years) and the median time between breast reconstruction and drainage was 35 days (range 4 to 235 days). Erythema and swelling were the most common presenting symptoms. The median volume of fluid evacuated at the time of drain placement was 70 mL. Drains were left in place for a median 14 days (range 6 to 34 days). Microorganisms were detected in the fluid in 12 of 30 drainage procedures, with Staphylococcus aureus being the most common microorganism. No further intervention was needed in 21 of 30 drainage procedures (70%). However, surgical intervention (removal of expanders) was needed following 6 (20%) drainages, and additional percutaneous drainage procedures were performed following 3 (10%) drainages. CONCLUSION Percutaneous drainage is an effective means of treating post operative fluid collections after expander-based breast reconstruction and can obviate the need for repeat surgery in most cases. PMID:23810309

Extended indications for percutaneous tracheostomy.

PubMed

Ben Nun, Alon; Altman, Eduard; Best, Lael Anson

2005-10-01

In recent years, percutaneous tracheostomy has become a routine practice in many hospitals. In the early publications, most authors considered adverse conditions such as short, fat neck or obesity as relative contraindications whereas cervical injury, coagulopathy, and emergency were regarded as absolute contraindications. More recently, several reports demonstrated the feasibility of percutaneous tracheostomy in patients with some of these contraindications. The aim of this study is to determine the safety and efficacy of percutaneous tracheostomy in conditions commonly referred to as contraindications. Between June 2000 and July 2001, 157 consecutive percutaneous tracheostomy procedures were performed on 154 critically ill adult patients in the general intensive care unit of a major tertiary care facility. The Griggs technique and Portex set were used at the bedside. All procedures were performed by staff thoracic surgeons and anesthesiologists experienced with the technique. Anatomical conditions, presence of coagulopathy and anti-coagulation therapy, demographics, and complication rates were recorded. Five of 157 procedures (154 patients owing to three repeat tracheostomies) had complications. In patients with normal anatomical conditions and coagulation profiles, there was one case of bleeding (50 cc to 120 cc) and one case of mild cellulitis around the stoma. In patients with adverse conditions, there was one case of bleeding (50 cc to 120 cc) and two cases of minor bleeding (< 50 cc). Patients with adverse conditions had a low complication rate similar to patients with normal conditions. For this reason, we believe that percutaneous tracheostomy is indicated in patients with short, fat neck; inability to perform neck extension; enlarged isthmus of thyroid; previous tracheostomy; or coagulopathy and anti-coagulation therapy.

Percutaneous Nephrolithotomy: Update, Trends, and Future Directions.

PubMed

Ghani, Khurshid R; Andonian, Sero; Bultitude, Matthew; Desai, Mihir; Giusti, Guido; Okhunov, Zhamshid; Preminger, Glenn M; de la Rosette, Jean

2016-08-01

Percutaneous nephrolithotomy (PCNL) is the surgical standard for treating large or complex renal stones. Since its inception, the technique of PCNL has undergone many modifications. To perform a collaborative review on the latest evidence related to outcomes and innovations in the practice of PCNL since 2000. A literature review was performed using the PubMed database between 2000 and July 2015, restricted to human species, adults, and the English language. The Medline search used a strategy including the following keywords: percutaneous nephrolithotomy, PNL, advances, trends, technique, and the Medical Subject Headings term percutaneous nephrostomy. Population-based studies have now provided a wealth of information regarding patient outcomes following PCNL. The complexity of the stone treated can be quantified using a variety of validated nephrolithometry classification systems. Increasing familiarity with the supine approach to PCNL has enabled simultaneous combined retrograde and antegrade surgery. Advances such as endoscopic guided percutaneous access may help urologists achieve access with less morbidity. Increasing miniaturization of equipment has led to the development of mini, micro, and ultramini techniques. The tubeless method of PCNL is now accepted practice with good evidence of safety in appropriately selected patients. Modern-day PCNL allows personalized stone management tailored to individual patient and surgeon factors. Future studies should continue to refine methods to assess complexity and safety and to determine consensus on the use of miniaturized PCNL. Modern-day percutaneous nephrolithotomy has transformed from an operation traditionally undertaken in one position, using one access method with one set of instrumentation and one surgeon, to one with a variety of options at each step. Published by Elsevier B.V.

Percutaneous repair or surgery for mitral regurgitation.

PubMed

Feldman, Ted; Foster, Elyse; Glower, Donald D; Glower, Donald G; Kar, Saibal; Rinaldi, Michael J; Fail, Peter S; Smalling, Richard W; Siegel, Robert; Rose, Geoffrey A; Engeron, Eric; Loghin, Catalin; Trento, Alfredo; Skipper, Eric R; Fudge, Tommy; Letsou, George V; Massaro, Joseph M; Mauri, Laura

2011-04-14

Mitral-valve repair can be accomplished with an investigational procedure that involves the percutaneous implantation of a clip that grasps and approximates the edges of the mitral leaflets at the origin of the regurgitant jet. We randomly assigned 279 patients with moderately severe or severe (grade 3+ or 4+) mitral regurgitation in a 2:1 ratio to undergo either percutaneous repair or conventional surgery for repair or replacement of the mitral valve. The primary composite end point for efficacy was freedom from death, from surgery for mitral-valve dysfunction, and from grade 3+ or 4+ mitral regurgitation at 12 months. The primary safety end point was a composite of major adverse events within 30 days. At 12 months, the rates of the primary end point for efficacy were 55% in the percutaneous-repair group and 73% in the surgery group (P=0.007). The respective rates of the components of the primary end point were as follows: death, 6% in each group; surgery for mitral-valve dysfunction, 20% versus 2%; and grade 3+ or 4+ mitral regurgitation, 21% versus 20%. Major adverse events occurred in 15% of patients in the percutaneous-repair group and 48% of patients in the surgery group at 30 days (P<0.001). At 12 months, both groups had improved left ventricular size, New York Heart Association functional class, and quality-of-life measures, as compared with baseline. Although percutaneous repair was less effective at reducing mitral regurgitation than conventional surgery, the procedure was associated with superior safety and similar improvements in clinical outcomes. (Funded by Abbott Vascular; EVEREST II ClinicalTrials.gov number, NCT00209274.).

Percutaneous intraductal radiofrequency ablation for treatment of biliary stent occlusion: A preliminary result

PubMed Central

Xia, Ning; Gong, Ju; Lu, Jian; Chen, Zhi-Jin; Zhang, Li-Yun; Wang, Zhong-Min

2017-01-01

AIM To assess the feasibility and effectiveness of a novel application of percutaneous intraductal radiofrequency (RF) for the treatment of biliary stent obstruction. METHODS We specifically report a retrospective study presenting the results of percutaneous intraductal RF in patients with biliary stent occlusion. A total of 43 cases involving biliary stent obstruction were treated by placing an EndoHPB catheter and percutaneous intraductal RF was performed to clean stents. The stent patency was evaluated by cholangiography and follow-up by contrast enhanced computed tomography or ultrasound after the removal of the drainage catheter. RESULTS Following the procedures, of the 43 patients, 40 survived and 3 died with a median survival of 80.5 (range: 30-243) d. One patient was lost to follow-up. One patient had the stent patent at the time of last follow-up. Two patients with stent blockage at 35 d and 44 d after procedure underwent percutaneous transhepatic drain insertion only. The levels of bilirubin before and after the procedure were 128 ± 65 μmol/L and 63 ± 29 μmol/L, respectively. There were no related complications (haemorrhage, bile duct perforation, bile leak or pancreatitis) and all patients’ stent patency was confirmed by cholangiography after the procedure, with a median patency time of 107 (range: 12-180) d. CONCLUSION This preliminary clinical study demonstrated that percutaneous intraductal RF is safe and effective for the treatment of biliary stent obstruction, increasing the duration of stent patency, although randomized controlled trials are needed to confirm the effectiveness of this approach. PMID:28348491

Better treatment strategies for patients with acute cholecystitis and American Society of Anesthesiologists classification 3 or greater.

PubMed

Yun, Sung Su; Hwang, Dae Wook; Kim, Se Won; Park, Sang Hwan; Park, Sang Jin; Lee, Dong Shick; Kim, Hong Jin

2010-07-01

Laparoscopic cholecystectomy is the best treatment choice for acute cholecystitis. However, it still carries high conversion and mortality rates. The purpose of this study was to find out better treatment strategies for high surgical risk patients with acute cholecystitis. Between January 2002 and June 2008, we performed percutaneous cholecystostomy instead of emergency cholecystectomy in 44 patients with acute cholecystitis and American Society of Anesthesiologists (ASA) classification 3 or greater. This was performed in 31 patients as a bridge procedure before elective cholecystectomy (bridge group) and as a palliative procedure in 11 patients (palliation group). The mean age of patients was 71.6 years (range 52-86 years). The mean ASA classifications before and after percutaneous cholecystostomy were 3.3 +/- 0.5 and 2.5 +/- 0.6, respectively, in the bridge group, and 3.6 +/- 0.7 and 3.1 +/- 1.0, in the palliation group, respectively. Percutaneous cholecystostomy was technically successful in all patients. There were two deaths after percutaneous cholecystostomy in the palliation group due to underlying ischemic heart disease and multiple organ failure. Resumption of oral intake was possible 2.9 +/- 1.8 days in the bridge group and 3.9 +/- 3.5 days in the palliation group after percutaneous cholecystostomy. We attempted 17 laparoscopic cholecystectomies and experienced one failure due to bile duct injury (success rate: 94.1%). The postoperative course of all cholecystectomy patients was uneventful. Percutaneous cholecystostomy is an effective bridge procedure before cholecystectomy in patients with acute cholecystitis and ASA classification 3 or greater.

"Corkscrew stenosis": defining and preventing a complication of percutaneous dilatational tracheostomy.

PubMed

Jacobs, Jordan V; Hill, David A; Petersen, Scott R; Bremner, Ross M; Sue, Richard D; Smith, Michael A

2013-03-01

The short-term safety of percutaneous dilatational tracheostomy has been widely demonstrated. However, less is known about their long-term complications. Through an illustrative case series, we present and define "corkscrew stenosis," a type of tracheal stenosis uniquely associated with percutaneous dilatational tracheostomy. Patients treated at our institution for tracheal stenosis after percutaneous dilatational tracheostomy were reviewed. Demographic data including gender, age, history of presentation, lesion morphology, imaging, and management was collected and evaluated. The pathology of the stenosis and the strategies for prevention are presented. From January, 2008 through December 2011, 11 patients had tracheal stenosis after percutaneous dilatational tracheostomy. The mean age was 54 ± 17 years and 55% were male. The stenotic lesions were characterized by a corkscrew morphology at the stoma site with a mean distance of 2.3 ± 0.8 cm from the vocal cords. Images of these lesions demonstrated disruption and fracture of the proximal tracheal cartilages and displacement of the anterior tracheal wall into the tracheal lumen. The majority of our patients required tracheal resection for definitive repair. We suggest that a unique form of tracheal stenosis can result from percutaneous dilatational tracheostomy. We observed corkscrew stenosis to be located proximally, associated with fractured tracheal rings, and morphologically appearing as interdigitation of these fractured rings. Recognizing corkscrew stenosis, its unique mechanism of formation, and technical means of prevention may be important in advancing the long-term safety of this procedure for critically ill patients who require prolonged ventilatory support. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

[Analysis on influencing factor of the complications of percutaneous dilational tracheotomy].

PubMed

Zhai, Xiang; Zhang, Jinling; Hang, Wei; Wang, Ming; Shi, Zhan; Mi, Yue; Hu, Yunlei; Liu, Gang

2015-01-01

To Analyze the influence factors on the complications of percutaneous dilational tracheotomy. Between August 2008 and February 2014, there were 3 450 patients with the indications of tracheotomy accepted percutaneous dilational tracheostomy, mainly using percutaneous dilational and percutaneous guide wire forceps in these cases. Statistical analysis was performed by SPSS 19.0 software on postoperative complications, the possible influence factors including age, gender, etiology, preoperative hypoxia, obesity, preoperative pulmonary infection, state of consciousness, operation method, operation doctor and whether with tracheal intubation. Among 3 450 patients, there were 164 cases with intraoperative or postoperative complications, including postoperative bleeding in 74 cases (2.14%), subcutaneous emphysema in 54 cases (1.57%), wound infection in 16 cases (0.46%), pneumothorax in 6 cases (0.17%), mediastinal emphysema in 5 cases (0.14%), operation failed and change to conventional incision in 4 cases (0.12%), tracheoesophageal fistula in 2 cases (0.06%), death in 3 cases(0.09%).Obesity, etiology, preoperative hypoxia, preoperative pulmonary infection, state of consciousness and operation method were the main influence factors, with significant statistical difference (χ(2) value was 0.010, 0.000, 0.002, 0.000, 0.000, 0.000, all P < 0.05). Gender, age, operation doctor and whether there was the endotracheal intubation were not the main influence factors. There was no significant statistical difference (P > 0.05). Although percutaneous dilational tracheostomy is safe, but the complications can also happen. In order to reduce the complications, it is need to pay attention to the factors of obesity, etiology, preoperative hypoxia, preoperative pulmonary infection, state of consciousness and operation method.

Delayed nonlinear cournot and bertrand dynamics with product differentiation.

PubMed

Matsumoto, Akio; Szidarovszky, Ferenc

2007-07-01

Dynamic duopolies will be examined with product differentiation and isoelastic price functions. We will first prove that under realistic conditions the equilibrium is always locally asymptotically stable. The stability can however be lost if the firms use delayed information in forming their best responses. Stability conditions are derived in special cases, and simulation results illustrate the complexity of the dynamism of the systems. Both price and quantity adjusting models are discussed.

Case report: perinephric-splenic fistula--a complication of percutaneous perinephric abscess drainage.

PubMed

Stewart, I E; Borland, C

1994-09-01

A case of acute perinephric abscess due to chronic parenchymal disease and calculi is presented. During percutaneous drainage a reno-splenic vein communication developed acutely. The aetiology and treatment complications of perinephric abscesses are reviewed.

Synchronisation and stability in river metapopulation networks.

PubMed

Yeakel, J D; Moore, J W; Guimarães, P R; de Aguiar, M A M

2014-03-01

Spatial structure in landscapes impacts population stability. Two linked components of stability have large consequences for persistence: first, statistical stability as the lack of temporal fluctuations; second, synchronisation as an aspect of dynamic stability, which erodes metapopulation rescue effects. Here, we determine the influence of river network structure on the stability of riverine metapopulations. We introduce an approach that converts river networks to metapopulation networks, and analytically show how fluctuation magnitude is influenced by interaction structure. We show that river metapopulation complexity (in terms of branching prevalence) has nonlinear dampening effects on population fluctuations, and can also buffer against synchronisation. We conclude by showing that river transects generally increase synchronisation, while the spatial scale of interaction has nonlinear effects on synchronised dynamics. Our results indicate that this dual stability - conferred by fluctuation and synchronisation dampening - emerges from interaction structure in rivers, and this may strongly influence the persistence of river metapopulations. © 2013 John Wiley & Sons Ltd/CNRS.

Stability of the bcc phase of 4He close to the melting curve: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Belonoshko, A. B.; Koči, L.; Rosengren, A.

2012-01-01

We have investigated whether the Aziz [J. Chem. Phys.JCPSA60021-960610.1063/1.438007 70, 4330 (1979)] model for 4He renders the body-centered cubic phase more stable than the face-centered cubic phase in the proximity of the melting curve. Using molecular dynamics, we have simulated these solid phases in equilibrium with the liquid at a number of densities. In contrast to previous free energy molecular dynamics calculations, the model stabilizes the body-centered cubic phase. The stability field is just 5∘ wide below the melting curve at pressures around 140 Kbar and about 70∘ wide at pressures around 750 Kbar. Considering that the body-centered cubic phase is dynamically unstable at low temperature, this result bears striking similarities to transition metal phase diagrams.

Effect of liquid-to-solid lipid ratio on characterizations of flurbiprofen-loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) for transdermal administration.

PubMed

Song, Aihua; Zhang, Xiaoshu; Li, Yanting; Mao, Xinjuan; Han, Fei

2016-08-01

The aim of this study is to evaluate the effect of liquid-to-solid lipid ratio on properties of flurbiprofen-loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), and to clarify the superiority of NLCs over SLNs for transdermal administration. Particle size, zeta potential, drug encapsulation efficiency, in vitro occlusion factor, differential scanning calorimetry, X-ray diffractometry, in vitro percutaneous permeation profile, and stability of SLNs and NLCs were compared. Particle size, zeta potential, drug encapsulation efficiency, in vitro occlusion factor, and in vitro percutaneous permeation amount of the developed NLCs were all <200 nm, < -20 mV, >78%, >35, and >240 μg/cm(2), respectively, however, for SLNs were 280 nm, -29.11 mV, 63.2%, 32.54, and 225.9 μg/cm(2), respectively. After 3 months storage at 4 °C and 25 °C, almost no significant differences between the evaluated parameters of NLCs were observed. However, for SLNs, particle size was increased to higher than 300 nm (4 °C and 25 °C), drug encapsulation efficiency was decreased to 51.2 (25 °C), in vitro occlusion factor was also decreased to lower than 25 (4 °C and 25 °C), and the cumulative amount was decreased to 148.9 μg/cm(2) (25 °C) and 184.4 μg/cm(2) (4 °C), respectively. And DSC and XRD studies indicated that not only the crystalline peaks of the encapsulated flurbiprofen disappeared but also obvious difference between samples and bulk Compritol® ATO 888 was seen. It could be concluded that liquid-to-solid lipid ratio has significant impact on the properties of SLNs and NLCs, and NLCs showed better stability than SLNs. Therefore, NLCs might be a better option than SLNs for transdermal administration.

Role of Joshi's external stabilization system with percutaneous screw fixation in high-energy tibial condylar fractures associated with severe soft tissue injuries.

PubMed

Gupta, Ashish-Kumar; Sapra, Rahul; Kumar, Rakesh; Gupta, Som-Prakash; Kaushik, Devwart; Gaba, Sahil; Bansal, Mahesh Chand; Dayma, Ratan Lal

2015-01-01

The treatment of high-energy tibial condylar fractures which are associated with severe soft tissue injuries remains contentious and challenging. In this study, we assessed the results of Joshi's external stabilization system (JESS) by using the principle of ligamentotaxis and percutaneous screw fixation for managing high-energy tibial condylar fractures associated with severe soft tissue injuries. Between June 2008 and June 2010, 25 consecutive patients who were 17e71 years (mean, 39.7), underwent the JESS fixation for high-energy tibial condylar fractures associated with severe soft tissue injuries. Out of 25 patients, 2 were lost during follow-up and in 1 case early removal of frame was done, leaving 22 cases for final follow-up. Among them, 11 had poor skin condition with abrasions and blisters and 2 were open injuries (Gustilo-Anderson grade I&II). The injury mechanisms were motor vehicle accidents (n=19), fall from a height (n=2) and assault (n=1). The fractures were classified according to Schatzker classification system. There were 7 type-V, 14 type-VI and 1 type-lV Schatzker's tibial plateau fractures. The average interval between the injury and surgery was 6.8 days (range 2-13). The average hospital stay was 13 days (range, 7-22). The average interval between the surgery and full weight bearing was 13.6 weeks (range 11-20). The average range of knee flexion was 121°(range 105°-135°). The normal extension of the knee was observed in 20 patients, and an extensor lag of 5°-8° was noted in 2 patients. The complications included superficial pin tract infections (n=4) with no knee stiffness. JESS with lag screw fixation combines the benefit of traction, external fixation, and limited internal fixation, at the same time as allowing the ease of access to the soft tissue for wound checks, pin care, dressing changes, measurement of compartment pressure, and the monitoring of the neurovascular status. In a nutshell, JESS along with screw fixation offers a promising alternative treatment for high- energy tibial condylar fractures associated with severe soft tissue injuries.

Sensitivity analysis of automatic flight control systems using singular value concepts

NASA Technical Reports Server (NTRS)

Herrera-Vaillard, A.; Paduano, J.; Downing, D.

1985-01-01

A sensitivity analysis is presented that can be used to judge the impact of vehicle dynamic model variations on the relative stability of multivariable continuous closed-loop control systems. The sensitivity analysis uses and extends the singular-value concept by developing expressions for the gradients of the singular value with respect to variations in the vehicle dynamic model and the controller design. Combined with a priori estimates of the accuracy of the model, the gradients are used to identify the elements in the vehicle dynamic model and controller that could severely impact the system's relative stability. The technique is demonstrated for a yaw/roll damper stability augmentation designed for a business jet.

Survey of needs and capabilities for wind tunnel testing of dynamic stability of aircraft at high angles of attack

NASA Technical Reports Server (NTRS)

Orlik-Ruckemann, K. J.

1973-01-01

A survey was conducted relative to future requirements for dynamic stability information for such aerospace vehicles as the space shuttle and advanced high performance military aircraft. High-angle-of-attack and high-Reynolds number conditions were emphasized. A review was made of the wind-tunnel capabilities in North America for measuring dynamic stability derivatives, revealing an almost total lack of capabilities that could satisfy these requirements. Recommendations are made regarding equipment that should be constructed to remedy this situation. A description is given of some of the more advanced existing capabilities, which can be used to at least partly satisfy immediate demands.

Necessary and sufficient conditions for the stability of a sleeping top described by three forms of dynamic equations

NASA Astrophysics Data System (ADS)

Ge, Zheng-Ming

2008-04-01

Necessary and sufficient conditions for the stability of a sleeping top described by dynamic equations of six state variables, Euler equations, and Poisson equations, by a two-degree-of-freedom system, Krylov equations, and by a one-degree-of-freedom system, nutation angle equation, is obtained by the Lyapunov direct method, Ge-Liu second instability theorem, an instability theorem, and a Ge-Yao-Chen partial region stability theorem without using the first approximation theory altogether.

Dynamic stabilization of classical Rayleigh-Taylor instability

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

Piriz, A. R.; Piriz, S. A.; Tahir, N. A.

2011-09-15

Dynamic stabilization of classical Rayleigh-Taylor instability is studied by modeling the interface vibration with the simplest possible wave form, namely, a sequence of Dirac deltas. As expected, stabilization results to be impossible. However, in contradiction to previously reported results obtained with a sinusoidal driving, it is found that in general the perturbation amplitude is larger than in the classical case. Therefore, no beneficial effect can be obtained from the vertical vibration of a Rayleigh-Taylor unstable interface between two ideal fluids.

Resource Allocation and Cross Layer Control in Wireless Networks

DTIC Science & Technology

2006-08-25

arrival rates lies within the capacity region of the network. The notion of controlling the system to maximize its stability region and the following...optimization problem (4.5) that must be solved at the beginning of 48 Dynamic Control for Network Stability each time slot requires in general knowledge...Dynamic Control for Network Stability ~ (c) ab (t) those of any other feasible algorithm, then for any time t 0; X ic U (c) i (t) "X b ~ (c) ab (t) X

The efficacy of a supervised and a home-based core strengthening programme in adults with poor core stability: a three-arm randomised controlled trial.

PubMed

Chuter, V H; de Jonge, X A K Janse; Thompson, B M; Callister, R

2015-03-01

Poor core stability is linked to a range of musculoskeletal pathologies and core-strengthening programmes are widely used as treatment. Treatment outcomes, however, are highly variable, which may be related to the method of delivery of core strengthening programmes. We investigated the effect of identical 8 week core strengthening programmes delivered as either supervised or home-based on measures of core stability. Participants with poor core stability were randomised into three groups: supervised (n=26), home-based (n=26) or control (n=26). Primary outcomes were the Sahrmann test and the Star Excursion Balance Test (SEBT) for dynamic core stability and three endurance tests (side-bridge, flexor and Sorensen) for static core stability. The exercise programme was devised and supervised by an exercise physiologist. Analysis of covariance on the change from baseline over the 8 weeks showed that the supervised group performed significantly better on all core stability measures than both the home-based and control group. The home-based group produced significant improvements compared to the control group in all static core stability tests, but not in most of the dynamic core stability tests (Sahrmann test and two out of three directions of the SEBT). Our results support the use of a supervised core-strengthening programme over a home-based programme to maximise improvements in core stability, especially in its dynamic aspects. Based on our findings in healthy individuals with low core stability, further research is recommended on potential therapeutic benefits of supervised core-strengthening programmes for pathologies associated with low core stability. ACTRN12613000233729. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Embolization of Bleeding Stomal Varices by Direct Percutaneous Approach

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

Arulraj, Ramakrishnan, E-mail: arulraas@yahoo.com; Mangat, Kamarjit S., E-mail: Kamarjit.mangat@uhb.nhs.uk; Tripathi, Dhiraj, E-mail: d.tripathi@bham.ac.uk

2011-02-15

Stomal varices can occur in patients with stoma in the presence of portal hypertension. Suture ligation, sclerotherapy, angiographic embolization, stoma revision, beta blockade, portosystemic shunt, and liver transplantation have been described as therapeutic options for bleeding stomal varices. We report the case of a 21-year-old patient with primary sclerosing cholangitis and colectomy with ileostomy for ulcerative colitis, where stomal variceal bleeding was successfully treated by direct percutaneous embolization. We consider percutaneous embolization to be an effective way of treating acute stomal bleeding in decompensated patients while awaiting decisions regarding shunt procedures or liver transplantation.

Percutaneous access versus surgical cut down for TAVR: Where do we go from here?

PubMed

Ates, Ismail; Cilingiroglu, Mehmet

2018-06-01

Transcatheter aortic valve replacement is now the standard of care for severe symptomatic aortic stenosis patients who are at high-surgical risk. Percutaneous approach without a surgical cut down has been increasingly adapted by some centers in USA. Percutaneous approach seems to be associated with shorter hospital stay, similar short and late vascular complications, less disabling stroke, similar mortality as well as significantly less hospital cost. However, this technique also requires operators to be able to manage any vascular complications using advanced endovascular interventions to achieve complete hemostasis. © 2018 Wiley Periodicals, Inc.

[Pancreatic tail pseudoaneurysm: percutaneous treatment by thrombin injection].

PubMed

Pacheco Jiménez, M; Moreno Sánchez, T; Moreno Rodríguez, F; Guillén Rico, M

2014-01-01

Visceral artery pseudoaneurysms secondary to acute and/or chronic pancreatitis are a relatively common and potentially serious complication. Endovascular techniques are the most currently accepted techniques, given the higher morbidity-mortality of surgery. The thrombosis of the pseudoaneurysm using an ultrasound-guided percutaneous thrombin injection is emerging as a useful option in those cases in which endovascular embolisation is not possible. We present the case of a patient with a pseudoaneurysm of the transverse pancreatic artery secondary to chronic pancreatitis, and successfully treated by administering percutaneous thrombin. Copyright © 2011 SERAM. Published by Elsevier Espana. All rights reserved.

Percutaneous epidural neurostimulation in modulation of paraplegic spasticity. Six case reports.

PubMed

Richardson, R R; Cerullo, L J; McLone, D G; Gutierrez, F A; Lewis, V

1979-01-01

Six cases of paraplegic, post-traumatic spasticity, alleviated by percutaneous epidural neurostimulation with temporary or permanent implanted neuroelectrodes from the L1 to L4 intervertebral levels are presented. Modulation of this spasticity and secondary beneficial physiological effects were achieved, including regulation of bowel regimens, production of sweating and piloerection below the level of the lesion, and morning erections. The main advantages of percutaneous epidural neurostimulation in modulating spasticity are the avoidance of destructive neurosurgical procedures, the regulation of secondary physiological and autonomic responses, the avoidance of antispasticity medications, and the reversibility of the neurostimulation procedure.

Endoscopic Ultrasound-guided drainage of an abdominal fluid collection following Whipple’s resection

PubMed Central

Jah, Asif; Jamieson, Neville; Huguet, Emmanuel; Griffiths, William; Carroll, Nicholas; Praseedom, Raaj

2008-01-01

Percutaneous aspiration and drainage of post-operative abdominal fluid collections is a well established standard technique. However, some fluid collections are not amenable to percutaneous drainage either due to location or the presence of surrounding visceral structures. Endoscopic Ultrasound (EUS) has been widely used for the drainage of pancreatitis-related abdominal fluid collections. However, there are no reports on the use of this technique in the post-operative setting. We report a case where the EUS-guided technique was used to drain a percutaneously inaccessible post-operative collection which had developed after Whipple’s resection. PMID:19058316

Percutaneous transhepatic drainage of lung abscess through a diaphragmatic fistula caused by a penetrating liver abscess.

PubMed

Taniguchi, Masako; Morita, Satoru; Ueno, Eiko; Hayashi, Mitsutoshi; Ishikawa, Motonao; Mae, Masahiro

2011-11-01

Liver abscesses occurring just below the diaphragm can penetrate or perforate the thoracic cavity, resulting in lung abscess or pyothorax. Although surgical or percutaneous transpleural drainage is often required in such cases, the latter approach has some risks, including hemothorax and bronchopleural fistula formation when the cavity is surrounded by normal lung parenchyma. The present report describes a treatment technique of percutaneous transhepatic drainage through the diaphragmatic fistula to avoid the risks of a transpulmonary approach in a case of lung abscess caused by a penetrating liver abscess.

Percutaneous self-injury to the femoral region caused by bur breakage during surgical extraction of a patient's impacted third molar.

PubMed

Yu, Tae Hoon; Lee, Jun; Kim, Bong Chul

2015-10-01

Extraction of an impacted third molar is one of the most frequently performed techniques in oral and maxillofacial surgery. Surgeons can suffer numerous external injuries while extracting a tooth, with percutaneous injuries to the hand being the most commonly reported. In this article, we present a case involving a percutaneous injury of the surgeon's femoral region caused by breakage of the fissure bur connected to the handpiece during extraction of the third molar. We also propose precautions to prevent such injuries and steps to be undertaken when they occur.

Retrospective comparison of mechanical percutaneous thrombectomy of hemodialysis arteriovenous grafts with the Arrow-Trerotola device and the lyse and wait technique.

PubMed

Vashchenko, Natalia; Korzets, Asher; Neiman, Chaim; Bachar, Gil N; Ori, Yaacov; Belenky, Alexander; Atar, Eli

2010-06-01

The purpose of our study was to determine whether pharmacologic thrombolysis with urokinase in the lyse and wait (L&W) technique compared with mechanical declotting using the Arrow-Trerotola percutaneous thrombectomy device is more efficient, safer, or less expensive in treating thrombosed hemodialysis grafts. The files of 157 patients who underwent arteriovenous graft declotting from 2000 to 2007 at one tertiary care center were reviewed. The study group included 83 women and 74 men with a mean age of 68 +/- 12 years (range, 27-95 years). A total of 563 procedures were performed: 427 with the L&W technique and 136 with mechanical percutaneous thrombectomy using the percutaneous thrombectomy device. The two types of procedures were compared for success rate, complications, average patency time, and cost. There were no statistically significant differences between the pharmacologic and mechanical procedures in immediate success rate (99% and 98%, respectively) or average patency time (5.44 months and 5.40 months, respectively). The L&W technique was considerably less expensive. Given its lower cost and equal efficacy and safety, L&W appears to be preferable to mechanical thrombolysis with a percutaneous thrombectomy device for initial arteriovenous hemodialysis graft declotting.

[Periprocedural and late complications after percutaneous closure of patent foramen ovale: a single centre experience].

PubMed

Węglarz, Przemysław; Konarska Kuszewska, Ewa; Spisak Borowska, Katarzyna; Machowski, Jerzy; Drzewiecka-Gerber, Agnieszka; Kuszewski, Piotr; Jackson, Christopher L; Opala, Grzegorz; Trusz Gluza, Maria

2012-01-01

Patent foramen ovale (PFO) is a potential risk factor for ischaemic stroke in young individuals. An interventional method of secondary stroke prevention in PFO patients is its percutaneous closure. To assess safety and effectiveness (i.e. lack of residual shunt) of percutaneous PFO closure in patients with history of cryptogenic cerebrovascular event. 149 patients (56 men/93 women), aged 39 ± 12 years, underwent percutaneous PFO closure. The implantation was performed under local anaesthesia, guided by trans-oesophageal echocardiography (TEE) and fluoroscopy. Follow-up trans-thoracic echocardiography (TTE) was performed at 1 month and follow-up TEE at 6-months. In cases of residual shunt, additional TEE was performed after ensuing 6 months. Effective PFO closure (no residual shunt) was achieved in 91.3% patients at 6 months and 95.3% patients at 12 months. In 2 patients transient atrial fibrillation was observed during the procedure. In 2 patients, a puncture site haematoma developed and in 1 patient superficial thrombophlebitis was noted. In 1 patient a small pericardial effusion was observed, which resolved at day 3 post-procedurally, after administration of non-steroidal anti-inflammatory drugs. Percutaneous PFO closure seems to be a safe procedure when performed in a centre with adequate expertise with regard to these procedures.

Percutaneous closure of patent foramen ovale without echocardiographic guidance.

PubMed

Jamshidi, Peiman; Wahl, Andreas; Windecker, Stephan; Schwerzmann, Markus; Seiler, Christian; Meier, Bernhard

2007-01-01

A percutaneous patent foramen ovale (PFO) closure procedure includes transesophageal or intracardiac echocardiographic guidance at many centers. We investigated the feasibility and complications of the PFO closure without echocardiography. A total of 420 consecutive patients (185 women and 235 men, mean age 51 +/- 12 years) underwent percutaneous PFO closure without echocardiographic guidance using 7 different devices. Of these, 106 patients (25%) had an associated atrial septal aneurysm. The implantation was successful in 418 patients (99%). There were 12 procedural complications (3%), including embolization of the device or of parts of it with successful percutaneous removal in 5 cases, pericardial tamponade requiring pericardiocentesis in 1 patient, air embolism with transient symptoms in 3 patients, and vascular access problems in 3 patients. In none of the cases, echocardiography had to be summoned during the case or its lack was associated with acute or subsequent problems. The fluoroscopy time and procedure time were 5.4 +/- 2.7 and 25 +/- 17 minutes, respectively. Transthoracic contrast echocardiography, 24 hours after device implantation, detected a residual shunt in 19% of the patients. Percutaneous PFO closure with fluoroscopic guidance only is feasible and has low complication rates, especially with Amplatzer PFO Occluders. The added time and cost of echocardiography during the procedure is not warranted.

Bicellar systems for in vitro percutaneous absorption of diclofenac.

PubMed

Rubio, L; Alonso, C; Rodríguez, G; Barbosa-Barros, L; Coderch, L; De la Maza, A; Parra, J L; López, O

2010-02-15

This work evaluates the effect of different bicellar systems on the percutaneous absorption of diclofenac diethylamine (DDEA) using two different approaches. In the first case, the drug was included in bicellar systems, which were applied on the skin and, in the second case, the skin was treated by applying bicellar systems without drug before to the application of a DDEA aqueous solution. The characterization of bicellar systems showed that the particle size decreased when DDEA was encapsulated. Percutaneous absorption studies demonstrated a lower penetration of DDEA when the drug was included in bicellar systems than when the drug was applied in an aqueous solution. This effect was possibly due to a certain rigidity of the bicellar systems caused by the incorporation of DDEA. The absorption of DDEA on skin pretreated with bicelles increased compared to the absorption of DDEA on intact skin. Bicelles without DDEA could cause certain disorganization of the SC barrier function, thereby facilitating the percutaneous penetration of DDEA subsequently applied. Thus, depending on their physicochemical parameters and on the application conditions, these systems have potential enhancement or retardant effects on percutaneous absorption that result in an interesting strategy, which may be used in future drug delivery applications. Copyright 2009 Elsevier B.V. All rights reserved.

Two Cases of Occupational Contact Urticaria Caused by Percutaneous Sensitization to Parvalbumin

PubMed Central

Sano, Akiyo; Yagami, Akiko; Suzuki, Kayoko; Iwata, Yohei; Kobayashi, Tsukane; Arima, Masaru; Kondo, Yasuto; Yoshikawa, Tetsushi; Matsunaga, Kayoko

2015-01-01

Background In recent years, it has been proposed that the primary mechanism for the development of food allergies is percutaneous sensitization. Since 2010, in Japan, the number of immediate-type wheat allergy due to hydrolyzed wheat protein has dramatically increased among those who have been using soap containing hydrolyzed wheat. This incidence supports the hypothesis that food allergens arise through percutaneous sensitization. Clinical Summary A 25-year-old man (case 1) and an 18-year-old girl (case 2) with atopic dermatitis visited our Department because of food allergy and hand eczema. After starting their work with fish, severe itchy eczema appeared on their hands. They subsequently started to experience oral allergic symptoms, intraoral itchiness and dyspnea after eating fish. Specific IgE antibodies were detected for many fishes, and skin prick tests showed positive reactions for a variety of fishes in both cases. Furthermore, the fluorescence intensities of specific IgE antibodies against parvalbumin from various types of fish in microarray immunoassay analysis showed positive reactions. We diagnosed them as contact urticaria caused by percutaneous sensitization to parvalbumin through job-related physical contact with fish. Conclusion The patients' histories and findings indicate the possibility of percutaneous sensitization through occupational exposure to parvalbumin, leading to food allergy. PMID:26464568

Asymptomatic hepatic portal venous gas with gastric emphysema as a chronic complication of gastrostomy tube placement: a case report.

PubMed

Sawano, Toyoaki; Nemoto, Tsuyoshi; Tsubokura, Masaharu; Leppold, Claire; Ozaki, Akihiko; Kato, Shigeaki; Kanazawa, Yukio

2016-08-24

Percutaneous endoscopic gastrostomy feeding is widely used as a route for enteral feeding for patients with impaired swallowing ability, particularly in older patients. Hepatic portal venous gas is a condition that may arise from several causes. Hepatic portal venous gas that develops after an endoscopic procedure is generally reported to be nonfatal, yet there is little information available concerning the characteristics of hepatic portal venous gas as a chronic complication of percutaneous endoscopic gastrostomy feeding. We experienced a case of hepatic portal venous gas that happened to be detected in an 81-year-old Japanese man with long-term percutaneous endoscopic gastrostomy use who was admitted to our hospital with aspiration pneumonia. While aspiration pneumonia was treated with antibiotics and suspension of tube feedings, he recovered from hepatic portal venous gas without any treatment. The presence of a percutaneous endoscopic gastrostomy tube may have induced hepatic portal venous gas through a mechanism in which vomiting led to increased abdominal pressure and eventually gastric emphysema. This case suggests that hepatic portal venous gas without any signs of bowel ischemia or emphysematous gastritis can resolve without treatment, which is a finding that could be helpful for clinicians who deal with those supported by percutaneous endoscopic gastrostomy feeding.

Occupational exposure of interns to blood in an area of high HIV seroprevalence.

PubMed

Karstaedt, A S; Pantanowitz, L

2001-01-01

To determine the epidemiology of work-related exposure to blood among interns. Interns were invited to complete anonymously a questionnaire concerning their past percutaneous and mucocutaneous exposures to blood. Chris Hani Baragwanath Hospital, Soweto, and Johannesburg Hospital, Gauteng, where HIV infection is common among patients. Ninety-eight interns (96%) were surveyed. Sixty-nine per cent of interns reported one or more percutaneous exposures to blood during the intern year, and 33% of interns recalled accidental percutaneous exposure to HIV-infected blood. Forty-five per cent recalled a mucocutaneous exposure to HIV-positive blood. Only 28 (64%) of 44 percutaneous injuries from HIV-infected patients were reported. During their student clinical training, 56% of interns had suffered a penetrating injury, and 18% recollected needlestick injuries involving HIV-infected patients. The most common mechanisms of injury included unexpected patient movement (23%), needle recapping (17%), and withdrawal of the needle (17%). Half of the injuries occurred during the first 4 months of internship. Only 22% of intern percutaneous exposures could have been avoided by following universal precautions. Intern and medical student exposure to blood is extremely common, but is markedly underreported. Strict compliance with universal precautions will not prevent the majority of exposures. Priorities should be the introduction of safer techniques and equipment, skills training and methods of reporting blood exposures.

Percutaneous radiofrequency rhizotomy for cervical zygapophyseal joint mediated neck pain: A retrospective review of outcomes in forty-four cases.

PubMed

Duff, Patricia; Das, Basabjit; McCrory, Connail

2016-01-01

Percutaneous radiofrequency (RF) rhizotomy of the medial branches of the dorsal rami from the spinal nerves is the standard treatment for cervical zygapophyseal joint mediated pain. There is a paucity of data regarding the longevity of analgesia following this procedure. To determine the duration of complete pain relief, analgesic consumption and any adverse events following percutaneous cervical RF rhizotomy. Retrospective chart review of patients who had undergone percutaneous cervical RF rhizotomy for zygapophyseal joint mediated neck pain. Patient reviews were undertaken by the pain consultant at 6 weeks, 6 months and 1 year following the procedure. Where follow-up was incomplete, the patient was assumed only to have had pain relief until their last review where complete pain relief had been documented. Analgesic consumption and any adverse events were recorded. The data was analysed using Microsoft Excel®. At 12 months 63.64% of patients were pain free. Median duration of complete pain relief was 52 weeks. Patients who experienced pain relief had ceased using prescription analgesia by their 6 week review. There were no repeat cervical RF rhizotomies, procedure related infections or unplanned hospital admissions. Percutaneous cervical RF rhizotomy is an effective treatment for cervical zygapophyseal joint mediated neck pain.

Clinical Problems In Coronary Angioscopy

NASA Astrophysics Data System (ADS)

Sherman, C. Todd

1989-06-01

I have been asked to talk about the clinical problems encountered when performing coronary angioscopy. By definition, this discussion will reflect negatively on the procedure. Nevertheless, after presenting some of the data, I hope you will leave thinking optimistically about the future of coronary angioscopy. The first topic that I would like to address, as shown in Figure 1, concerns the goals for coronary angioscopy. What great discoveries might we ekpect from this tool? Is the potential benefit worthy of a large research and development investment? Then, assuming these goals are meritorious, I will compare the difficulties of percutaneous angioscopy with that of a more fully explored technique- intraoperative angioscopy. I will next describe the differences between percutaneous angioscopy of peripheral vasculature, a procedure enjoying more widespread use, and percutaneous coronary angioscopy (a technique less often utilized). I will then outline the basic requirements for any percutaneous coronary angioscopy system whose attributes can resolve some of the inherent challenges of the technique. Even if this hypothetical instrument were developed and proved to be safe and functional, angioscopy will always have intrinsic limitations. I will next outline these shortcomings. This will be followed by a more optimistic topic- a review of the published studies that have utilized percutaneous coronary angioscopy. Finally, I will speculate on developments in coronary angioscopy for the near future.

Percutaneous Biopsy of Osteoid Osteomas Prior to Percutaneous Treatment Using Two Different Biopsy Needles

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

Laredo, Jean-Denis, E-mail: jean-denis.laredo@lrb.aphp.fr; Hamze, Bassam; Jeribi, Riadh

2009-09-15

Biopsy is usually performed as the first step in percutaneous treatment of osteoid osteomas prior to laser photocoagulation. At our institution, 117 patients with a presumed diagnosis of osteoid osteoma had a trephine biopsy before a percutaneous laser photocoagulation. Biopsies were made using two different types of needles. A Bonopty biopsy needle (14-gauge cannula, 16-gauge trephine needle; Radi Medical Systems, Uppsala, Sweden) was used in 65 patients, and a Laurane biopsy needle (11-gauge cannula, 12.5-gauge trephine needle; Laurane Medical, Saint-Arnoult, France) in 43 patients. Overall biopsy results were positive for osteoid osteoma in 83 (70.9%) of the 117 cases. Themore » Laurane needle provided a significantly higher positive rate (81.4%) than the Bonopty needle (66.1%; p < 0.05). This difference was not due to the size of the nidus, which was similar in the two groups (p < 0.05) and may be an effect of differences in needle caliber (12.5 vs. 14 gauge) as well as differences in needle design. The rate of positive biopsy results obtained in the present series with the Laurane biopsy needle is, to our knowledge, the highest rate reported in series dealing with percutaneous radiofrequency ablation and laser photocoagulation of osteoid osteomas.« less

[Percutaneous ablation of malignant kidney tumors in rabbits by low frequency radio energy].

PubMed

Moskovitz, B; Nativ, O; Sabo, E; Barbara, Y; Mordohovich, D; Kaftori, Y; Shalhav, A; Goldwasser, B

1998-01-01

Radio-frequency (RF) current has been used successfully to ablate normal human tissue. To investigate further the clinical application of this modality in tumors, we studied the potential of using RF percutaneously to destroy experimental kidney tumors. 35 outbred albino rabbits underwent direct-implantation of renal VX2 tumor during open surgery. After 21 days, ultrasonography was performed to show tumor presence and size. A shielded RF needle was designed to be inserted percutaneously through an introduction needle. An electrical insulation shield covering the RF needle was retractable, controlling the length of exposure of the RF needle inside the tissue. 22 days after tumor implantation, RF was applied via this special needle using a ZoMed International RF generator. In one group of rabbits the procedure was performed under direct vision during open surgery, while in another group treatment was percutaneous, the needle guided by palpation of the tumor. Rabbits were killed 3 days later and revealed 4-25 mm intra-tumoral RF-induced lesions. A direct relation was found between lesion size and the power and duration of RF applied (at 7.5 W, R = 0.48, and P = 0.32). Based on our preliminary results we can conclude that RF may have clinical applications in the near future for percutaneous local tumor control in parenchymal organs.

PERCUTANEOUS RADIOFREQUENCY ASSISTED LIVER PARTITION WITH PORTAL VEIN EMBOLIZATION FOR STAGED HEPATECTOMY (PRALPPS).

PubMed

Giménez, Mariano E; Houghton, Eduardo J; Davrieux, C Federico; Serra, Edgardo; Pessaux, Patrick; Palermo, Mariano; Acquafresca, Pablo A; Finger, Caetano; Dallemagne, Bernard; Marescaux, Jacques

2018-03-01

When a major hepatic resection is necessary, sometimes the future liver remnant is not enough to maintain sufficient liver function and patients are more likely to develop liver failure after surgery. To test the hypothesis that performing a percutaneous radiofrecuency liver partition plus percutaneous portal vein embolization (PRALPPS) for stage hepatectomy in pigs is feasible. Four pigs (Sus scrofa domesticus) both sexes with weights between 25 to 35 kg underwent percutaneous portal vein embolization with coils of the left portal vein. By contrasted CT, the difference between the liver parenchyma corresponding to the embolized zone and the normal one was identified. Immediately, using the fusion of images between ultrasound and CT as a guide, radiofrequency needles were placed percutaneouslyand then ablated until the liver partition was complete. Finally, hepatectomy was completed with a laparoscopic approach. All animals have survived the procedures, with no reported complications. The successful portal embolization process was confirmed both by portography and CT. In the macroscopic analysis of the pieces, the depth of the ablation was analyzed. The hepatic hilum was respected. On the other hand, the correct position of the embolization material on the left portal vein could be also observed. "Percutaneous radiofrequency assisted liver partition with portal vein embolization" (PRALLPS) is a feasible procedure.

A New Device for Percutaneous Elevation of the Depressed Fractures of Tibial Condyles

PubMed Central

Ravindranath, V.S.; Kumar, Madhusudan; Murthy, G.V.S.

2012-01-01

Introduction: Monocondylar tibia plateau fractures with non-comminuted fragments can be treated using percutaneous screws. Currently indirect methods of reduction are used and thus the technique is limited to fragments with less than 5 mm depression. The first author has designed a device for direct elevation and reduction of the fragments thus potentially expanding the indications of percutaneous screws to fragments with >5mm depression Technical Note: A total of ten cases were treated by this method of percutaneous elevation of the depressed fractures of lateral condyles of the Tibia using this device. Device was inserted through a bony window on the anteromedial surface of tibia. The inner piston of the device in slowly hammered inside thus elevating the depressed fragment. Elevation of fragment could be achieved in all the cases. The fractures were fixed with cancellous screws applied percutaneously. There were no cases with loss of fixation or subsidence of the fragment. All cases achieved radiological union and have good knee function at follow up Conclusion: The new device is able to elevate unicondylar tibia plateau fragments with no subsidence or loss of fixation in our series. A longer follow up in a larger sample will be needed to establish the technique. PMID:27298860

Reality of obesity paradox: Results of percutaneous coronary intervention in Middle Eastern patients.

PubMed

Jarrah, Mohamad; Hammoudeh, Ayman J; Khader, Yousef; Tabbalat, Ramzi; Al-Mousa, Eyas; Okkeh, Osama; Alhaddad, Imad A; Tawalbeh, Loai Issa; Hweidi, Issa M

2018-04-01

Objective The aim of this study was to assess the baseline clinical characteristics, coronary angiographic features, and adverse cardiovascular events during hospitalization and at 1 year of follow-up in obese patients compared with overweight and normal/underweight patients. Methods A prospective, multicenter study of consecutive patients undergoing percutaneous coronary intervention was performed. Results Of 2425 enrolled patients, 699 (28.8%) were obese, 1178 (48.6%) were overweight, and 548 (22.6%) were normal/underweight. Obese patients were more likely to be female and to have a higher prevalence of diabetes, hypertension, hypercholesterolemia, or previous percutaneous coronary intervention. Acute coronary syndrome was the indication for percutaneous coronary intervention in 77.0% of obese, 76.4% of overweight, and 77.4% of normal/underweight patients. No significant differences in the prevalence of multi-vessel coronary artery disease or multi-vessel percutaneous coronary intervention were found among the three groups. Additionally, no significant differences were found in stent thrombosis, readmission bleeding rates, or cardiac mortality among the three groups during hospitalization, at 1 month, and at 1 year. Conclusion The major adverse cardiovascular event rate was the same among the three groups throughout the study period. Accordingly, body mass index is considered a weak risk factor for cardiovascular comorbidities in Arab Jordanian patients.

Self-reported occupational health problems among Libyan dentists.

PubMed

Arheiam, Arheiam; Ingafou, Mohamed

2015-01-01

To investigate the prevalence of the most common occupation-related health problems as well as factors associated with their incidence among dental practitioners. A cross-sectional, questionnaire-based survey of Libyan dental practitioners. Participants provided information regarding their experience of occupationally related problems they encountered over the past 12 months which included inquiries about musculoskeletal pain, percutaneous injuries, allergy, eye and sight problems, and hearing problems. Musculoskeletal problems were the most frequently reported (48.2%), followed by percutaneous injuries (35%), eye problems (22%), allergy (11%) and hearing problems (7.6%). Musculoskeletal problems were significantly higher among dentists who work in private sector, full timer as well as those who prefer to work in a sitting position (p=0.021, 0.027 and 0.008, respectively). Practitioners with less than 5 years in service reported significantly higher percentage of percutaneous injuries (p=0.027) than their senior counterparts, whereas practitioners who spent more than 10 years in service were more likely to suffer from visual disturbances (p=0.033). The findings of this study indicate that musculoskeletal problems and percutaneous injuries are the most commonly reported occupational health problems among dentists, whereas allergic reactions and hearing problems are the least reported ones. Dentists should use alternate working positions to minimise musculoskeletal problems and adopt more effective strategies to prevent percutaneous injuries particularly among novices.

[Study on pulmonary lesions in which nontuberculous mycobacteria were detected by percutaneous aspiration--a proposal to add "culture positivity of percutaneous aspiration material" to the bacteriological diagnostic criteria of pulmonary nontuberculous mycobacterial diseases].

PubMed

Nakahara, Yasuharu; Mochizuki, Yoshiro; Kawamura, Tetsuji; Sasaki, Shin; Morimoto, Akie; Mizumori, Yasuyuki; Tsukamoto, Hiroaki; Watanabe, Etsuko; Yokoyama, Toshihide

2013-03-01

Culture positivity of percutaneous aspiration material" is not included in the current bacteriological criteria for diagnosis of pulmonary nontuberculous mycobacterial (NTM) diseases, which were published by the Infectious Diseases Society of America (IDSA)/American Thoracic Society (ATS) in 2007 or those released by the Japanese Society for Tuberculosis in 2008. However, percutaneous aspiration is a reliable technique for the detection of causative microorganisms isolated from the focus of infection. We discuss the benefits of including positive culture of percutaneous aspiration material in the bacteriological diagnostic criteria of pulmonary NTM diseases. We reviewed the radiological images and clinical courses of pulmonary diseases in which NTM cultures were obtained from percutaneously aspirated materials at our hospital from 1991 to 2011. Aspiration was carried out under local anesthesia, usually with fluoroscopic guidance. After percutaneous insertion of a 22-gauge needle attached to a 20-mL syringe containing about 3 mL of saline, the lesion specimen was withdrawn together with the saline. After the needle was pulled out, the aspirated material and saline were transferred to test tubes for cytological and microbiological examinations. In patients with thin-walled cavitary lesions, saline was injected into the cavity and then aspirated. Percutaneous aspiration was performed in 2,742 patients and NTM disease was detected in 51 patients. Of these 51 patients, 12 had solitary nodular lesions, and in many of these patients, no NTM bacilli could be detected in the sputa or bronchial washing specimens. Mycobacterium avium was identified in 10 of the 12 cases. Four of these 10 patients were followed up after their diagnosis without any treatment: 3 showed spontaneous reduction in lesion size, while 1 patient's condition remained unchanged. Four of the remaining 6 cases were treated with anti-NTM medications, and lesion size reduced in 2 cases, while no change or deterioration was seen in the other 2. Aspiration from solitary small cavitary lesions showed a relatively high number of NTM colonies. Pneumothorax was the only complication of the aspiration procedure. If the diagnostic criteria for pulmonary NTM diseases include positive culture in percutaneous aspiration material, the diagnosis of solitary nodular NTM lesions would become easier; at present, these lesions are often diagnosed only upon surgical resection. Further, clinical studies on the possibility of spontaneous shrinkage of the solitary lesion and the value of its medical treatment would be promoted. Aspiration can easily differentiate NTM disease from pulmonary abscess or fungal infection in patients with a solitary lesion or small cavity.

Stability Calculation Method of Slope Reinforced by Prestressed Anchor in Process of Excavation

PubMed Central

Li, Zhong; Wei, Jia; Yang, Jun

2014-01-01

This paper takes the effect of supporting structure and anchor on the slope stability of the excavation process into consideration; the stability calculation model is presented for the slope reinforced by prestressed anchor and grillage beam, and the dynamic search model of the critical slip surface also is put forward. The calculation model of the optimal stability solution of each anchor tension of the whole process is also given out, through which the real-time analysis and checking of slope stability in the process of excavation can be realized. The calculation examples indicate that the slope stability is changed with the dynamic change of the design parameters of anchor and grillage beam. So it is relatively more accurate and reasonable by using dynamic search model to determine the critical slip surface of the slope reinforced by prestressed anchor and grillage beam. Through the relationships of each anchor layout and the slope height of various stages of excavation, and the optimal stability solution of prestressed bolt tension design value in various excavation stages can be obtained. The arrangement of its prestressed anchor force reflects that the layout of the lower part of bolt and the calculation of slope reinforcement is in line with the actual. These indicate that the method is reasonable and practical. PMID:24683319

Stability calculation method of slope reinforced by prestressed anchor in process of excavation.

PubMed

Li, Zhong; Wei, Jia; Yang, Jun

2014-01-01

This paper takes the effect of supporting structure and anchor on the slope stability of the excavation process into consideration; the stability calculation model is presented for the slope reinforced by prestressed anchor and grillage beam, and the dynamic search model of the critical slip surface also is put forward. The calculation model of the optimal stability solution of each anchor tension of the whole process is also given out, through which the real-time analysis and checking of slope stability in the process of excavation can be realized. The calculation examples indicate that the slope stability is changed with the dynamic change of the design parameters of anchor and grillage beam. So it is relatively more accurate and reasonable by using dynamic search model to determine the critical slip surface of the slope reinforced by prestressed anchor and grillage beam. Through the relationships of each anchor layout and the slope height of various stages of excavation, and the optimal stability solution of prestressed bolt tension design value in various excavation stages can be obtained. The arrangement of its prestressed anchor force reflects that the layout of the lower part of bolt and the calculation of slope reinforcement is in line with the actual. These indicate that the method is reasonable and practical.

Stability and dynamical properties of material flow systems on random networks

NASA Astrophysics Data System (ADS)

Anand, K.; Galla, T.

2009-04-01

The theory of complex networks and of disordered systems is used to study the stability and dynamical properties of a simple model of material flow networks defined on random graphs. In particular we address instabilities that are characteristic of flow networks in economic, ecological and biological systems. Based on results from random matrix theory, we work out the phase diagram of such systems defined on extensively connected random graphs, and study in detail how the choice of control policies and the network structure affects stability. We also present results for more complex topologies of the underlying graph, focussing on finitely connected Erdös-Réyni graphs, Small-World Networks and Barabási-Albert scale-free networks. Results indicate that variability of input-output matrix elements, and random structures of the underlying graph tend to make the system less stable, while fast price dynamics or strong responsiveness to stock accumulation promote stability.

New level of vehicle comfort and vehicle stability via utilisation of the suspensions anti-dive and anti-squat geometry

NASA Astrophysics Data System (ADS)

Lindvai-Soos, Daniel; Horn, Martin

2018-07-01

In this article a novel vehicle dynamics control concept is designed for a vehicle equipped with wheel individual electric traction machines, electronically controlled brakes and semi-active suspensions. The suspension's cross-couplings between traction forces and vertical forces via anti-dive and anti-squat geometry is utilised in the control concept to improve driving comfort and driving stability. The control concept is divided into one main and two cascaded branches. The main controller consists of a multivariable vehicle dynamics controller and a control allocation scheme to improve the vehicle's driving comfort. The cascaded feedback loops maintain the vehicle's stability according to wheel slip and vehicle sideslip. The performance of the combined vehicle dynamics controller is compared to a standard approach in simulation. It can be stated that the controller piloting semi-active suspensions together with brake and traction devices enables a superior performance regarding comfort and stability.

Dynamical control of a quantum Kapitza pendulum in a spin-1 BEC

NASA Astrophysics Data System (ADS)

Hoang, Thai; Gerving, Corey; Land, Ben; Anquez, Martin; Hamley, Chris; Chapman, Michael

2013-05-01

We demonstrate dynamic stabilization of an unstable strongly interacting quantum many-body system by periodic manipulation of the phase of the collective states. The experiment employs a spin-1 atomic Bose condensate that has spin dynamics analogous to a non-rigid pendulum in the mean-field limit. The condensate spin is initialized to an unstable (hyperbolic) fixed point of the phase space, where subsequent free evolution gives rise to spin-nematic squeezing and quantum spin mixing. To stabilize the system, periodic microwave pulses are applied that manipulate the spin-nematic fluctuations and limit their growth. The range of pulse periods and phase shifts with which the condensate can be stabilized is measured and compares well with a linear stability analysis of the problem. C.D. Hamley, et al., ``Spin-Nematic Squeezed Vacuum in a Quantum Gas,'' Nature Physics 8, 305-308 (2012).

Macroeconomic Stabilization When the Natural Real Interest Rate Is Falling

ERIC Educational Resources Information Center

Buttet, Sebastien; Roy, Udayan

2015-01-01

The authors modify the Dynamic Aggregate Demand-Dynamic Aggregate Supply model in Mankiw's widely used intermediate macroeconomics textbook to discuss monetary policy when the natural real interest rate is falling over time. Their results highlight a new role for the central bank's inflation target as a tool of macroeconomic stabilization. They…

Scalable Online Network Modeling and Simulation

DTIC Science & Technology

2005-08-01

ONLINE NETWORK MODELING AND SIMULATION 6. AUTHOR(S) Boleslaw Szymanski , Shivkumar Kalyanaraman, Biplab Sikdar and Christopher Carothers 5...performance for a wide range of parameter values (parameter sensitivity), understanding of protocol stability and dynamics, and studying feature ...a wide range of parameter values (parameter sensitivity), understanding of protocol stability and dynamics, and studying feature interactions

The contact condition influence on stability and energy efficiency of quadruped robot

NASA Astrophysics Data System (ADS)

Lei, Jingtao; Wang, Tianmiao; Gao, Feng

2008-10-01

Quadruped robot has attribute of serial and parallel manipulator with multi-loop mechanism, with more DOF of each leg and intermittent contact with ground during walking, the trot gait of quadruped robot belongs to dynamic waking, compared to the crawl gait, the walking speed is higher, but the robot becomes unstable, it is difficult to keep dynamically stable walking. In this paper, we mainly analyze the condition for the quadruped robot to realize dynamically stable walking, establish centroid orbit equation based on ZMP (Zero Moment Point) stability theory, on the other hand , we study contact impact and friction influence on stability and energy efficiency. Because of the periodic contact between foots and ground, the contact impact and friction are considered to establish spring-damp nonlinear dynamics model. Robot need to be controlled to meet ZMP stability condition and contact constraint condition. Based on the virtual prototyping model, we study control algorithm considering contact condition, the contact compensator and friction compensator are adopted. The contact force and the influence of different contact conditions on the energy efficiency during whole gait cycle are obtained.

Repeated pulse feeding induces functional stability in anaerobic digestion.

PubMed

De Vrieze, Jo; Verstraete, Willy; Boon, Nico

2013-07-01

Anaerobic digestion is an environmental key technology in the future bio-based economy. To achieve functional stability, a minimal microbial community diversity is required. This microbial community should also have a certain 'elasticity', i.e. the ability to rapidly adapt to suboptimal conditions or stress. In this study it was evaluated whether a higher degree of functional stability could be achieved by changing the feeding pattern, which can change the evenness, dynamics and richness of the bacterial community. The first reactor (CSTR stable ) was fed on daily basis, whereas the second reactor (CSTR dynamic ) was fed every 2 days. Average biogas production was 0.30 l CH4 l(-1) day(-1) in both reactors, although daily variation was up to four times higher in the CSTR dynamic compared with the CSTR stable during the first 50 days. Bacterial analysis revealed that this CSTR dynamic had a two times higher degree of bacterial community dynamics. The CSTR dynamic also appeared to be more tolerant to an organic shock load of 8 g COD l(-1) and ammonium levels up to 8000 mg TAN l(-1). These results suggest that the regular application of a limited pulse of organic material and/or a variation in the substrate composition might promote higher functional stability in anaerobic digestion. © 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Evaluating competing forces constraining glacial grounding-line stability (Invited)

NASA Astrophysics Data System (ADS)

Powell, R. D.

2013-12-01

Stability of grounding lines of marine-terminating glaciers and ice sheets is of concern due to their importance in governing rates of ice mass loss and consequent sea level rise during global warming. Although processes are similar at tidewater and floating grounding zones their relative magnitudes in terms of their influence on grounding-line stability vary between these two end members. Processes considered Important for this discussion are ice dynamics, ice surface melting and crevassing, ocean dynamics, subglacial sediment and water dynamics, and subglacial bed geometries. Models have continued to improve in their representation of these complex interactions but reliable field measurements and data continue to be hard earned and too few to properly constrain the range of boundary conditions in this complicated system. Some data will be presented covering a range of regimes from Alaska, Svalbard and Antarctica. Certainly more data are required on subglacial sediment/water dynamics and fluxes to fully represent the spectrum of glacial regimes and to assess the significance of grounding-zone sediment systems in counteracting the other processes to force grounding-line stability. Especially important here is constraining the duration of the stability that could be maintained by sediment flux - present data appear to show that it is likely to be a limited period.

Kinetics and mechanical stability of the fibril state control fibril formation time of polypeptide chains: A computational study

NASA Astrophysics Data System (ADS)

Kouza, Maksim; Co, Nguyen Truong; Li, Mai Suan; Kmiecik, Sebastian; Kolinski, Andrzej; Kloczkowski, Andrzej; Buhimschi, Irina Alexandra

2018-06-01

Fibril formation resulting from protein misfolding and aggregation is a hallmark of several neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Despite much progress in the understanding of the protein aggregation process, the factors governing fibril formation rates and fibril stability have not been fully understood. Using lattice models, we have shown that the fibril formation time is controlled by the kinetic stability of the fibril state but not by its energy. Having performed all-atom explicit solvent molecular dynamics simulations with the GROMOS43a1 force field for full-length amyloid beta peptides Aβ40 and Aβ42 and truncated peptides, we demonstrated that kinetic stability can be accessed via mechanical stability in such a way that the higher the mechanical stability or the kinetic stability, the faster the fibril formation. This result opens up a new way for predicting fibril formation rates based on mechanical stability that may be easily estimated by steered molecular dynamics.

Spectral analysis of point-vortex dynamics: first application to vortex polygons in a circular domain

NASA Astrophysics Data System (ADS)

Speetjens, M. F. M.; Meleshko, V. V.; van Heijst, G. J. F.

2014-06-01

The present study addresses the classical problem of the dynamics and stability of a cluster of N-point vortices of equal strength arranged in a polygonal configuration (‘N-vortex polygons’). In unbounded domains, such N-vortex polygons are unconditionally stable for N\\leqslant 7. Confinement in a circular domain tightens the stability conditions to N\\leqslant 6 and a maximum polygon size relative to the domain radius. This work expands on existing studies on stability and integrability by a first giving an exploratory spectral analysis of the dynamics of N vortex polygons in circular domains. Key to this is that the spectral signature of the time evolution of vortex positions reflects their qualitative behaviour. Expressing vortex motion by a generic evolution operator (the so-called Koopman operator) provides a rigorous framework for such spectral analyses. This paves the way to further differentiation and classification of point-vortex behaviour beyond stability and integrability. The concept of Koopman-based spectral analysis is demonstrated for N-vortex polygons. This reveals that conditional stability can be seen as a local form of integrability and confirms an important generic link between spectrum and dynamics: discrete spectra imply regular (quasi-periodic) motion; continuous (sub-)spectra imply chaotic motion. Moreover, this exposes rich nonlinear dynamics as intermittency between regular and chaotic motion and quasi-coherent structures formed by chaotic vortices. Dedicated to the memory of Slava Meleshko, a dear friend and inspiring colleague.

Reliability and Construct Validity of Limits of Stability Test in Adolescents Using a Portable Forceplate System.

PubMed

Alsalaheen, Bara; Haines, Jamie; Yorke, Amy; Broglio, Steven P

2015-12-01

To examine the reliability, convergent, and discriminant validity of the limits of stability (LOS) test to assess dynamic postural stability in adolescents using a portable forceplate system. Cross-sectional reliability observational study. School setting. Adolescents (N=36) completed all measures during the first session. To examine the reliability of the LOS test, a subset of 15 participants repeated the LOS test after 1 week. Not applicable. Outcome measurements included the LOS test, Balance Error Scoring System, Instrumented Balance Error Scoring System, and Modified Clinical Test for Sensory Interaction on Balance. A significant relation was observed among LOS composite scores (r=.36-.87, P<.05). However, no relation was observed between LOS and static balance outcome measurements. The reliability of the LOS composite scores ranged from moderate to good (intraclass correlation coefficient model 2,1=.73-.96). The results suggest that the LOS composite scores provide unique information about dynamic postural stability, and the LOS test completed at 100% of the theoretical limit appeared to be a reliable test of dynamic postural stability in adolescents. Clinicians should use dynamic balance measurement as part of their balance assessment and should not use static balance testing (eg, Balance Error Scoring System) to make inferences about dynamic balance, especially when balance assessment is used to determine rehabilitation outcomes, or when making return to play decisions after injury. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Effect of active arm swing to local dynamic stability during walking.

PubMed

Wu, Yu; Li, Yue; Liu, An-Min; Xiao, Fei; Wang, Yin-Zhi; Hu, Fei; Chen, Jin-Ling; Dai, Ke-Rong; Gu, Dong-Yun

2016-02-01

Arm swing is an essential component in regulating dynamic stability of the whole body during walking, while the contribution of active arm swing to local dynamic stability of different motion segments remains unclear. This study investigated the effects of arm swing under natural arm swing condition and active arm swing condition on local dynamic stability and gait variability of the trunk segments (C7 and T10 joint) and lower extremity joints (hip, knee and ankle joint). The local divergence exponents (λs) and mean standard deviation over strides (MeanSD) of 24 young healthy adults were calculated while they were walking on treadmill with two arm swing conditions at their preferred walking speed (PWS). We found that in medial-lateral direction, both λs and MeanSD values of the trunk segments (C7 and T10 joint) in active arm swing condition were significantly lower than those in natural arm swing condition (p<0.05), while no significant difference of λs or MeanSD in lower extremity joints (hip, knee and ankle joint) was found between two arm swing conditions (p>0.05, respectively). In anterior-posterior and vertical direction, neither λs nor MeanSD values of all body segments showed significant difference between two arm swing conditions (p>0.05, respectively). These findings indicate that active arm swing may help to improve the local dynamic stability of the trunk segments in medial-lateral direction. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparative effectiveness of lumbar stabilization, dynamic strengthening, and Pilates on chronic low back pain: randomized clinical trial

PubMed Central

Bhadauria, Esha A.; Gurudut, Peeyoosha

2017-01-01

The aim of the present study was to compare three different forms of exercises namely lumbar stabilization, dynamic strengthening, and Pilates on chronic low back pain (LBP) in terms of pain, range of motion, core strength and function. In this study, 44 subjects suffering from non-specific LBP for more than 3 months were randomly allocated into the lumbar stabilization group, the dynamic strengthening group, and the Pilates group. Ten sessions of exercises for 3 weeks were prescribed along with interferential current and hot moist pack. Pain was assessed by visual analog scale, functional affection by modified Oswestry Disability Questionnaire, range of motion by assessing lumbar flexion and extension by modified Schober test and core strength was assessed by pressure biofeedback on day 1 and day 10 of the treatment. There was reduction of pain, improvement in range of motion, functional ability and core strength in all the 3 exercise groups. The improvement was significantly greater in the lumbar stabilization group for all the outcome measures, when compared the posttreatment after 10th session. Pairwise comparison showed that there was greater reduction of disability in the Pilates group than the dynamic strengthening group. It was concluded that the lumbar stabilization is more superior compared to the dynamic strengthening and Pilates in chronic nonspecific LBP. However, long-term benefits need to be assessed and compared with prospective follow-up studies. PMID:29114516

Clinical application of the Panjabi neutral zone hypothesis: the Stabilimax NZ posterior lumbar dynamic stabilization system.

PubMed

Yue, James J; Timm, Jens P; Panjabi, Manohar M; Jaramillo-de la Torre, Jorge

2007-01-15

The neutral zone (NZ) is a region of intervertebral motion around the neutral posture where little resistance is offered by the passive spinal column. The NZ appears to be a clinically important measure of spinal stability function. Its size may increase with injury to the spinal column, which in turn may result in spinal instability or low-back pain. Dynamic stabilization systems are designed to support and stabilize the spine while maintaining range of motion (ROM). The Stabilimax NZ device has been designed to reduce the NZ after spinal injury to treat pain while preserving ROM.

Flap-Lag-Torsion Stability in Forward Flight

NASA Technical Reports Server (NTRS)

Panda, B.; Chopra, I.

1985-01-01

An aeroelastic stability of three-degree flap-lag-torsion blade in forward flight is examined. Quasisteady aerodynamics with a dynamic inflow model is used. The nonlinear time dependent periodic blade response is calculated using an iterative procedure based on Floquet theory. The periodic perturbation equations are solved for stability using Floquet transition matrix theory as well as constant coefficient approximation in the fixed reference frame. Results are presented for both stiff-inplane and soft-inplane blade configurations. The effects of several parameters on blade stability are examined, including structural coupling, pitch-flap and pitch-lag coupling, torsion stiffness, steady inflow distribution, dynamic inflow, blade response solution and constant coefficient approximation.