WorldWideScience

Sample records for bidirectional bronchiolo-pulmonar shunting

  1. Model of pulmonary fluid traffic homeostasis based on respiratory cycle pressure, bidirectional bronchiolo-pulmonar shunting and water evaporation.

    Science.gov (United States)

    Kurbel, Sven; Kurbel, Beatrica; Gulam, Danijela; Spajić, Borislav

    2010-06-01

    The main puzzle of the pulmonary circulation is how the alveolar spaces remain dry over a wide range of pulmonary vascular pressures and blood flows. Although normal hydrostatic pressure in pulmonary capillaries is probably always below 10 mmHg, well bellow plasma colloid pressure of 25 mmHg, most textbooks state that some fluid filtration through capillary walls does occur, while the increased lymph drainage prevents alveolar fluid accumulation. The lack of a measurable pressure drop along pulmonary capillaries makes the classic description of Starling forces unsuitable to the low pressure, low resistance pulmonary circulation. Here presented model of pulmonary fluid traffic describes lungs as a matrix of small vascular units, each consisting of alveoli whose capillaries are anastomotically linked to the bronchiolar capillaries perfused by a single bronchiolar arteriole. It proposes that filtration and absorption in pulmonary and in bronchiolar capillaries happen as alternating periods of low and of increased perfusion pressures. The model is based on three levels of filtration control: short filtration phases due to respiratory cycle of the whole lung are modulated by bidirectional bronchiolo-pulmonar shunting independently in each small vascular unit, while fluid evaporation from alveolar groups further tunes local filtration. These mechanisms are used to describe a self-sustaining regulator that allows optimal fluid traffic in different settings. The proposed concept is used to describe development of pulmonary edema in several clinical entities (exercise in wet or dry climate, left heart failure, people who rapidly move to high altitudes, acute cyanide and carbon monoxide poisoning, large pulmonary embolisms). .

  2. Superior vena cava syndrome after pulsatile bidirectional Glenn shunt procedure: Perioperative implications

    Directory of Open Access Journals (Sweden)

    Neema Praveen

    2009-01-01

    Full Text Available Bidirectional superior cavopulmonary shunt (bidirectional Glenn shunt is generally performed in many congenital cardiac anomalies where complete two ventricle circulations cannot be easily achieved. The advantages of BDG shunt are achieved by partially separating the pulmonary and systemic venous circuits, and include reduced ventricular preload and long-term preservation of myocardium. The benefits of additional pulsatile pulmonary blood flow include the potential growth of pulmonary arteries, possible improvement in arterial oxygen saturation, and possible prevention of development of pulmonary arteriovenous malformations. However, increase in the systemic venous pressure after BDG with additional pulsatile blood flow is known. We describe the peri-operative implications of severe flow reversal in the superior vena cava after pulsatile BDG shunt construction in a child who presented for surgical interruption of the main pulmonary artery.

  3. Predictive simulation of bidirectional Glenn shunt using a hybrid blood vessel model.

    Science.gov (United States)

    Li, Hao; Leow, Wee Kheng; Chiu, Ing-Sh

    2009-01-01

    This paper proposes a method for performing predictive simulation of cardiac surgery. It applies a hybrid approach to model the deformation of blood vessels. The hybrid blood vessel model consists of a reference Cosserat rod and a surface mesh. The reference Cosserat rod models the blood vessel's global bending, stretching, twisting and shearing in a physically correct manner, and the surface mesh models the surface details of the blood vessel. In this way, the deformation of blood vessels can be computed efficiently and accurately. Our predictive simulation system can produce complex surgical results given a small amount of user inputs. It allows the surgeon to easily explore various surgical options and evaluate them. Tests of the system using bidirectional Glenn shunt (BDG) as an application example show that the results produc by the system are similar to real surgical results.

  4. Impact of evolving strategy on clinical outcomes and central pulmonary artery growth in patients with bilateral superior vena cava undergoing a bilateral bidirectional cavopulmonary shunt.

    Science.gov (United States)

    Honjo, Osami; Tran, Kim-Chi D; Hua, Zhongdong; Sapra, Priya; Alghamdi, Abdullah A; Russell, Jennifer L; Caldarone, Christopher A; Van Arsdell, Glen S

    2010-09-01

    We reported a high incidence of thrombosis, central pulmonary artery hypoplasia, and mortality for bilateral bidirectional cavopulmonary shunts. We hypothesized that technical modifications in the cavopulmonary anastomosis and anticoagulation would limit thrombus and central pulmonary artery hypoplasia, and thereby improve outcomes. Sixty-one patients (median age, 8.4 months; weight, 6.6 kg) underwent bilateral bidirectional cavopulmonary shunt from 1990 to 2007. The cohort was divided into 2 groups: 1) the conventional group (1990-1999, n = 37) and 2) the V-shaped group, with a hemi-Fontan or modification in which the cavae were anastomosed to the pulmonary artery adjacent to each other so they formed the appearance of a V (1999-2007, n = 24). Central and branch pulmonary artery growth, survival, and reinterventions were determined. The pre-Fontan study showed equivalent superior venae cavae and Nakata indices. The central pulmonary artery index and central pulmonary artery/Nakata index ratio were significantly higher in the V-shaped group (P analysis showed anastomotic strategy, low saturation, and thrombosis were predictors for death. Anastomotic strategy, lack of anticoagulation, thrombosis, and small superior venae cavae were predictors for reintervention (P strategy affected reintervention. Anastomotic strategy and postoperative thrombus affected mortality. 2010 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  5. Low-dose prospectively electrocardiogram-gated axial dual-source CT angiography in patients with pulsatile bilateral bidirectional Glenn Shunt: an alternative noninvasive method for postoperative morphological estimation.

    Directory of Open Access Journals (Sweden)

    Xiaopeng Ji

    Full Text Available To explore the clinical value of low-dose prospectively electrocardiogram-gated axial dual-source CT angiography (low-dose PGA scanning, CTA in patients with pulsatile bilateral bidirectional Glenn shunt (bBDG as an alternative noninvasive method for postoperative morphological estimation.Twenty patients with pulsatile bBDG (mean age 4.2±1.6 years underwent both low-dose PGA scanning and conventional cardiac angiography (CCA for the morphological changes. The morphological evaluation included the anatomy of superior vena cava (SVC and pulmonary artery (PA, the anastomotic location, thrombosis, aorto-pulmonary collateral circulation, pulmonary arteriovenous malformations, etc. Objective and subjective image quality was assessed. Bland-Altman analysis and linear regression analyses were used to evaluate the correlation on measurements between CTA and CCA. Effective radiation dose of both modalities was calculated.The CT attenuation value of bilateral SVC and PA was higher than 300 HU. The average subjective image quality score was 4.05±0.69. The morphology of bilateral SVC and PA was displayed completely and intuitively by CTA images. There were 24 SVC above PA and 15 SVC beside PA. Thrombosis was found in 1 patient. Collateral vessels were detected in 13 patients. No pulmonary arteriovenous malformation was found in our study. A strong correlation (R2>0.8, P0.The mean effective dose of CTA and CCA was 0.50±0.17 mSv and 4.85±1.34 mSv respectively.CT angiography with a low-dose PGA scanning is an accurate and reliable noninvasive examination in the assessment of morphological changes in patients with pulsatile bBDG.

  6. Congenital Intrahepatic Portosystemic Shunts

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Woong Hee; Kim, Young Tong; Jou, Sung Shick; Shin, Hyeong Cheol [Soonchunhyang University, Asan (Korea, Republic of)

    2008-12-15

    Intrahepatic portosystemic shunts are an anomalous connection between the portal vein and hepatic vein/IVC, which may be either congenital or acquired secondary to liver cirrhosis or portal hypertension. Cases of congenital intrahepatic shunts are usually encountered in children and may spontaneously resolve. We report 5 cases of congenital intrahepatic portosystemic shunts in neonates and an adult

  7. [Shunt and short circuit].

    Science.gov (United States)

    Rangel-Abundis, Alberto

    2006-01-01

    Shunt and short circuit are antonyms. In French, the term shunt has been adopted to denote the alternative pathway of blood flow. However, in French, as well as in Spanish, the word short circuit (court-circuit and cortocircuito) is synonymous with shunt, giving rise to a linguistic and scientific inconsistency. Scientific because shunt and short circuit made reference to a phenomenon that occurs in the field of the physics. Because shunt and short circuit are antonyms, it is necessary to clarify that shunt is an alternative pathway of flow from a net of high resistance to a net of low resistance, maintaining the stream. Short circuit is the interruption of the flow, because a high resistance impeaches the flood. This concept is applied to electrical and cardiovascular physiology, as well as to the metabolic pathways.

  8. Shunt detection and measurement

    International Nuclear Information System (INIS)

    Grossman, W.

    1986-01-01

    Detection, localization, and quantification of intracardiac shunts are an integral part of the hemodynamic evaluation of patients with congenital heart disease. In most cases, an intracardiac shunt is suspected on the basis of the clinical evaluation of the patient prior to catheterization. However, there are several circumstances in which data obtained at catheterization should alert the cardiologist to look for a shunt that previously had not been suspected

  9. Ventriculoperitoneal Shunt Migration

    Directory of Open Access Journals (Sweden)

    Justin P Puller

    2017-01-01

    Full Text Available History of present illness: A 40-year-old female presented to our ED with left upper abdominal pain and flank pain. The pain had begun suddenly 2 hours prior when she was reaching into a freezer to get a bag of frozen vegetables. She described the pain as sharp, constant, severe, and worse with movements and breathing. The pain radiated to the left shoulder. On review of systems, the patient had mild dyspnea and nausea. She denied fever, chills, headache, vision changes, vomiting, or urinary symptoms. Her medical history was notable for obstructive sleep apnea, gastroesophageal reflux disease, arthritis, fibromyalgia, depression, obesity, and idiopathic intracranial hypertension. For the latter, she had a VP (ventriculoperitoneal shunt placed 14 years prior to this visit. She had a history of 2 shunt revisions, the most recent 30 days before this ED visit. Significant findings: An immediate post-op abdominal x-ray performed after the patient’s VP shunt revision 30 days prior to this ED visit reveals the VP shunt tip in the mid abdomen. A CT of the abdomen performed on the day of the ED visit reveals the VP shunt tip interposed between the spleen and the diaphragm. Discussion: VP shunts have been reported to migrate to varied locations in the thorax and abdomen. Incidence of abdominal complications of VP shunt placement ranges from 10%-30%, and can include pseudocyst formation, migration, peritonitis, CSF ascites, infection, and viscus perforation. Incidence of distal shunt migration is reported as 10%, and most previously reported cases occurred in pediatric patients.1 A recent retrospective review cited BMI greater than thirty and previous shunt procedure as risk factors for distal shunt migration.2 The patient in the case presented had a BMI of 59 and 3 previous shunt procedures.

  10. Transjugular intrahepatic portosystemic shunt

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae Hyung; Han, Joon Koo; Chung, Jin Wook; Han, Man Chung [Seoul National University College of Medicidne, Seoul (Korea, Republic of)

    1992-05-15

    As a new interventional procedure for the control of variceal bleeding, a portosystemic shunt can be established with the installment of metallic stent through the transjugular approach. In order to evaluate the clinical usefulness of the procedure, transjugular intrahepatic portosystemic shunt procedure were performed in 5 patients with variceal bleeding due to liver cirrhosis. The metallic stents were mainly a self expandable Wallstent (Schneider, Switzerland), An 8 to 10 mm shunt was formed by the insertion of the stent and balloon dilatation after puncture of the proximal portal vein from the right or middle hepatic vein. The patency of the shunt was proven by portography after the procedure. The portal pressure measured in 3 patients before and after the procedure improved with decrease from 31 mmHg to 25 mmHg. The procedure failed in 1 patient due to pre-existing portal vein thrombosis. During the follow-up period from 1 month to 4 months, shunts were patent in all 4 patients. However, hepatic encephalopathy occurred in one patient one week following the procedure. Though the follow-up period was not long enough for full evaluation, we found the transjugular intrahepatic portosystemic shunt was a safe and effective procedure for the control of variceal bleeding by lowering the portal pressure. For the appropriate application for this procedure, the optimal size of the shunt and optical degree of the resultant decompression are yet to be determined in the future.

  11. Hydrocephalus and Shunts

    Science.gov (United States)

    ... of a problem. Because of the complexity, a neurosurgeon is the best person to diagnosis and treat ... type of shunt is best for whom. So neurosurgeons usually pick ones that they think are best. ...

  12. Flux shunts for undulators

    International Nuclear Information System (INIS)

    Hoyer, E.; Chin, J.; Hassenzahl, W.V.

    1993-05-01

    Undulators for high-performance applications in synchrotron-radiation sources and periodic magnetic structures for free-electron lasers have stringent requirements on the curvature of the electron's average trajectory. Undulators using the permanent magnet hybrid configuration often have fields in their central region that produce a curved trajectory caused by local, ambient magnetic fields such as those of the earth. The 4.6 m long Advanced Light Source (ALS) undulators use flux shunts to reduce this effect. These flux shunts are magnetic linkages of very high permeability material connecting the two steel beams that support the magnetic structures. The shunts reduce the scalar potential difference between the supporting beams and carry substantial flux that would normally appear in the undulator gap. Magnetic design, mechanical configuration of the flux shunts and magnetic measurements of their effect on the ALS undulators are described

  13. Early mediastinal seroma secondary to modified Blalock-Taussig shunts - successful management by percutaneous drainage

    International Nuclear Information System (INIS)

    Connolly, Bairbre L.; Temple, Michael J.; Chait, Peter G.; Restrepo, Ricardo; Adatia, Ian

    2003-01-01

    Large symptomatic mediastinal seroma following modified-BT shunts, traditionally required revisional thoracotomy. We describe percutaneous image-guided pigtail catheter drainage in the successful treatment of early mediastinal seroma secondary to PTFE Blalock-Taussig shunt, avoiding thoracotomy. A retrospective review of all relevant clinical and imaging records in five patients was performed. All five presented with intermittent stridor, respiratory distress and/or episodic desaturation within 6 weeks of their surgery. In four of five infants, percutaneous drainage was effective and reoperation was avoided. In one of five, rather than urgent surgical evacuation and BT shunt revision, we were able to perform an elective stage-II bidirectional Glenn SVC-RA anastamosis in a stable infant. There were no complications. Percutaneous image-guided drainage of mediastinal seroma secondary to PTFE-BT shunt is a safe, minimally invasive, and effective treatment. This may avoid BT shunt revision. (orig.)

  14. Bidirectional optical scattering facility

    Data.gov (United States)

    Federal Laboratory Consortium — Goniometric optical scatter instrument (GOSI)The bidirectional reflectance distribution function (BRDF) quantifies the angular distribution of light scattered from a...

  15. Pathophysiology of shunt dysfunction in shunt treated hydrocephalus

    DEFF Research Database (Denmark)

    Blegvad, C.; Skjolding, A D; Broholm, H

    2013-01-01

    We hypothesized that shunt dysfunction in the ventricular catheter and the shunt valve is caused by different cellular responses. We also hypothesized that the cellular responses depend on different pathophysiological mechanisms....

  16. Aqueous shunts for glaucoma.

    Science.gov (United States)

    Tseng, Victoria L; Coleman, Anne L; Chang, Melinda Y; Caprioli, Joseph

    2017-07-28

    Aqueous shunts are employed to control intraocular pressure (IOP) for people with primary or secondary glaucomas who fail or are not candidates for standard surgery. To assess the effectiveness and safety of aqueous shunts for reducing IOP in glaucoma compared with standard surgery, another type of aqueous shunt, or modification to the aqueous shunt procedure. We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 8), MEDLINE Ovid (1946 to August 2016), Embase.com (1947 to August 2016), PubMed (1948 to August 2016), LILACS (Latin American and Caribbean Health Sciences Literature Database) (1982 to August 2016), ClinicalTrials.gov (www.clinicaltrials.gov); searched 15 August 2016, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 15 August 2016. We did not use any date or language restrictions in the electronic search for trials. We last searched the electronic databases on 15 August 2016. We also searched the reference lists of identified trial reports and the Science Citation Index to find additional trials. We included randomized controlled trials that compared various types of aqueous shunts with standard surgery or to each other in eyes with glaucoma. Two review authors independently screened search results for eligibility, assessed the risk of bias, and extracted data from included trials. We contacted trial investigators when data were unclear or not reported. We graded the certainty of the evidence using the GRADE approach. We followed standard methods as recommended by Cochrane. We included 27 trials with a total of 2099 participants with mixed diagnoses and comparisons of interventions. Seventeen studies reported adequate methods of randomization, and seven reported adequate allocation concealment. Data collection and follow-up times varied.Four trials compared an aqueous shunt (Ahmed or Baerveldt) with trabeculectomy, of which

  17. Ventriculoperitoneal shunt infections in children

    African Journals Online (AJOL)

    1991-02-02

    Feb 2, 1991 ... shunts: epidemiology, clinical manifestations and therapy.] Infecr Vis 1975;. 13: 543-552. 4. Odio C, McCracken GH jun, Nelson JD. CSF shunt infections in pediatrics, a seven-year experience. Am] Dis Child 1984; 138: 1103-1108. 5. Meirovitch J, Kitai-Cohen Y, Keren G, Fiendler G, Rubinstein E. Cerebro-.

  18. Congenital extrahepatic portosystemic shunts

    Energy Technology Data Exchange (ETDEWEB)

    Murray, Conor P.; Yoo, Shi-Joon; Babyn, Paul S. [Department of Diagnostic Imaging, Hospital for Sick Children, 555 University Avenue, M5G 1X8, Toronto, Ontario (Canada)

    2003-09-01

    A congenital extrahepatic portosystemic shunt (CEPS) is uncommon. A type 1 CEPS exists where there is absence of intrahepatic portal venous supply and a type 2 CEPS where this supply is preserved. The diagnosis of congenital portosystemic shunt is important because it may cause hepatic encephalopathy. To describe the clinical and imaging features of three children with CEPS and to review the cases in the published literature. The diagnostic imaging and medical records for three children with CEPS were retrieved and evaluated. An extensive literature search was performed. Including our cases, there are 61 reported cases of CEPS, 39 type 1 and 22 type 2. Type 1 occurs predominantly in females, while type 2 shows no significant sexual preponderance. The age at diagnosis ranges from 31 weeks of intrauterine life to 76 years. Both types of CEPS have a number of associations, the most common being nodular lesions of the liver (n=25), cardiac anomalies (n=19), portosystemic encephalopathy (n=10), polysplenia (n=9), biliary atresia (n=7), skeletal anomalies (n=5), and renal tract anomalies (n=4). MRI is recommended as an important means of diagnosing and classifying cases of CEPS and examining the associated cardiovascular and hepatic abnormalities. Screening for CEPS in patients born with polysplenia is suggested. (orig.)

  19. Congenital extrahepatic portosystemic shunts

    International Nuclear Information System (INIS)

    Murray, Conor P.; Yoo, Shi-Joon; Babyn, Paul S.

    2003-01-01

    A congenital extrahepatic portosystemic shunt (CEPS) is uncommon. A type 1 CEPS exists where there is absence of intrahepatic portal venous supply and a type 2 CEPS where this supply is preserved. The diagnosis of congenital portosystemic shunt is important because it may cause hepatic encephalopathy. To describe the clinical and imaging features of three children with CEPS and to review the cases in the published literature. The diagnostic imaging and medical records for three children with CEPS were retrieved and evaluated. An extensive literature search was performed. Including our cases, there are 61 reported cases of CEPS, 39 type 1 and 22 type 2. Type 1 occurs predominantly in females, while type 2 shows no significant sexual preponderance. The age at diagnosis ranges from 31 weeks of intrauterine life to 76 years. Both types of CEPS have a number of associations, the most common being nodular lesions of the liver (n=25), cardiac anomalies (n=19), portosystemic encephalopathy (n=10), polysplenia (n=9), biliary atresia (n=7), skeletal anomalies (n=5), and renal tract anomalies (n=4). MRI is recommended as an important means of diagnosing and classifying cases of CEPS and examining the associated cardiovascular and hepatic abnormalities. Screening for CEPS in patients born with polysplenia is suggested. (orig.)

  20. Subacute bacterial endocarditis and subsequent shunt nephritis from ventriculoatrial shunting 14 years after shunt implantation

    DEFF Research Database (Denmark)

    Burström, Gustav; Andresen, Morten; Bartek, Jiri Jr.

    2014-01-01

    of causing subacute bacterial endocarditis and subsequent shunt nephritis. The patient was successfully treated with antibiotics combined with ventriculoatrial shunt removal and endoscopic third ventriculocisternostomy (VCS). This case illustrates the nowadays rare, but potentially severe complication...... of subacute bacterial endocarditis and shunt nephritis. It also exemplifies the VCS as an alternative to implanting foreign shunt systems for CSF diversion....

  1. Quadrupole shunt experiments at SPEAR

    International Nuclear Information System (INIS)

    Corbett, W.J.; Hettel, R.O.; Nuhn, H.-D.

    1996-05-01

    As part of a program to align and stabilize the SPEAR storage ring, a switchable shunt resistor was installed on each quadrupole to bypass a small percentage of the magnet current. The impact of a quadrupole shunt is to move the electron beam orbit in proportion to the off-axis beam position at the quadrupole, and to shift the betatron tune. Initially, quadrupole shunts in SPEAR were used to position the electron beam in the center of the quadrupoles. This provided readback offsets for nearby beam position monitors, and helped to steer the photon beams with low-amplitude corrector currents. The shunt-induced tune shift measurements were then processed in MAD to derive a lattice model

  2. Quadrupole shunt experiments at SPEAR

    International Nuclear Information System (INIS)

    Corbett, W.J.; Hettel, R.O.; Nuhn, H.

    1997-01-01

    As part of a program to align and stabilize the SPEAR storage ring, a switchable shunt resistor was installed on each quadrupole to bypass a small percentage of the magnet current. The impact of a quadrupole shunt is to move the electron beam orbit in proportion to the off-axis beam position at the quadrupole and to shift the betatron tune. Initially, quadrupole shunts in SPEAR were used to position the electron beam in the center of the quadrupoles. This provided readback offsets for nearby beam position monitors and helped to steer the photon beams with low-amplitude corrector currents. The shunt-induced tune shift measurements were then processed in MAD to derive a lattice model. copyright 1997 American Institute of Physics

  3. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... a stent is placed to keep the connection open and allow it to bring blood draining from ... veins within the liver. The shunt is kept open by the placement of a small, tubular metal ...

  4. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... bear denotes child-specific content. Related Articles and Media Radiation Dose in X-Ray and CT Exams Contrast Materials Venography Images related to Transjugular Intrahepatic Portosystemic Shunt (TIPS) Sponsored ...

  5. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... story about radiology? Share your patient story here Images × Image Gallery Radiologist and patient consultation. View full size ... X-Ray and CT Exams Contrast Materials Venography Images related to Transjugular Intrahepatic Portosystemic Shunt (TIPS) Sponsored ...

  6. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... Intrahepatic Portosystemic Shunt (TIPS)? What are some common uses of the procedure? How should I prepare? What does the equipment look like? How does the procedure work? How is the procedure performed? What will I ...

  7. Failed Ventriculoperitoneal Shunt: Is Retrograde Ventriculosinus Shunt a Reliable Option?

    Science.gov (United States)

    Oliveira, Matheus Fernandes de; Teixeira, Manoel Jacobsen; Reis, Rodolfo Casimiro; Petitto, Carlo Emanuel; Gomes Pinto, Fernando Campos

    2016-08-01

    Currently, the treatment of hydrocephalus is mainly carried out through a ventriculoperitoneal shunt (VPS) insertion. However, in some cases, there may be surgical revisions and requirement of an alternative distal site for shunting. There are several described distal sites, and secondary options after VPS include ventriculopleural and ventriculoatrial shunt, which have technical difficulties and harmful complications. In this preliminary report we describe our initial experience with retrograde ventriculosinus shunt (RVSS) after failed VPS. In 3 consecutive cases we applied RVSS to treat hydrocephalus in shunt-dependent patients who had previously undergone VPS revision and in which peritoneal space was full of adhesions and fibrosis. RVSS was performed as described by Shafei et al., with some modifications to each case. All 3 patients kept the same clinical profile after RVSS, with no perioperative or postoperative complications. However, revision surgery was performed in the first operative day in 1 out of 3 patients, in which the catheter was not positioned in the superior sagittal sinus. We propose that in cases where VPS is not feasible, RVSS may be a safe and applicable second option. Nevertheless, the long-term follow-up of patients and further learning curve must bring stronger evidence. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. A Statistical Theory of Bidirectionality

    Science.gov (United States)

    DeLoach, Richard; Ulbrich, Norbert

    2013-01-01

    Original concepts related to the quantification and assessment of bidirectionality in strain-gage balances were introduced by Ulbrich in 2012. These concepts are extended here in three ways: 1) the metric originally proposed by Ulbrich is normalized, 2) a categorical variable is introduced in the regression analysis to account for load polarity, and 3) the uncertainty in both normalized and non-normalized bidirectionality metrics is quantified. These extensions are applied to four representative balances to assess the bidirectionality characteristics of each. The paper is tutorial in nature, featuring reviews of certain elements of regression and formal inference. Principal findings are that bidirectionality appears to be a common characteristic of most balance outputs and that unless it is taken into account, it is likely to consume the entire error budget of a typical balance calibration experiment. Data volume and correlation among calibration loads are shown to have a significant impact on the precision with which bidirectionality metrics can be assessed.

  9. Aqueous shunt implantation in glaucoma

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2017-01-01

    Full Text Available Aqueous shunts or glaucoma drainage devices are increasingly utilized in the management of refractory glaucoma. The general design of the most commonly-used shunts is based on the principles of the Molteno implant: ie. a permanent sclerostomy (tube, a predetermined bleb area (plate and diversion of aqueous humour to the equatorial region and away from the limbal subconjunctival space. These three factors make aqueous shunts more resistant to scarring as compared to trabeculectomy. The two most commonly used shunts are the Ahmed Glaucoma Valve, which contains a flow-restrictor, and the non-valved Baervedlt Glaucoma Implant. While the valved implants have a lower tendency to hypotony and related complications, the non-valved implants with larger, more-biocompatible end plate design, achieve lower intraocular pressures with less encapsulation. Non-valved implants require additional suturing techniques to prevent early hypotony and a number of these methods will be described. Although serious shunt-related infection is rare, corneal decompensation and diplopia are small but significant risks.

  10. Ventriculoperitoneal shunt blockage by hydatid cyst

    Directory of Open Access Journals (Sweden)

    Abrar A Wani

    2013-01-01

    Full Text Available Ventriculoperitoneal (VP shunt is one of the commonest procedures done in neurosurgical practice throughout the world. One of the commonest problems after putting the VP shunt is the shunt obstruction, which can be due to varied causes. Shunt obstruction secondary to the parasitic infections is rarely seen. We are presenting a 15-year-old child, a case of operated cerebral hydatid cyst with hydrocephalus. She presented with shunt malfunction after 1 year of surgical excision of the hydatid cyst. Revision of the VP shunt was done and peroperatively, it was found that the shunt tubing was obstructed due to small hydatid cysts. This is the first reported case of VP shunt obstruction by hydatid cyst.

  11. 30 CFR 56.6401 - Shunting.

    Science.gov (United States)

    2010-07-01

    ... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Explosives Electric Blasting § 56.6401 Shunting. Except during testing— (a) Electric detonators shall be kept shunted until connected to the blasting line or wired into a blasting round; (b) Wired rounds shall be kept shunted until...

  12. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Transjugular Intrahepatic Portosystemic Shunt ( ...

  13. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    Medline Plus

    Full Text Available ... Portosystemic Shunt (TIPS) Sponsored by Please note RadiologyInfo.org is not a medical facility. Please contact your ... links: For the convenience of our users, RadiologyInfo .org provides links to relevant websites. RadiologyInfo.org , ACR ...

  14. Ventriculo-pleural shunt patency study

    International Nuclear Information System (INIS)

    Yeates, K.

    2000-01-01

    Full text: A twenty-four year old male was admitted to hospital complaining of headaches, drowsiness and blurred vision. He suffered from congenital hydrocephalus and had had a ventriculo-peritoneal shunt inserted in infancy. This had undergone many revisions due to persistent peritoneal infections and had recently been replaced with a ventriculo-pleural shunt. The symptoms described suggested shunt blockage and he was referred for a Shunt Patency Study. The current shunt is a HAKIM Programmable Valve Shunt System and the opening pressure was 12cm of CSF (within the normal range). Forty megabecquerels of filtered 99 Tc m O 4 was injected into the pre-chamber of the shunt. Serial images and counts were obtained for twenty-five minutes after the injection. The images showed the tracer flowing from the shunt within the first ten minutes. At twenty minutes almost all of the tracer had drained from the shunt and was present in the right pleural cavity, indicating shunt patency. This study is presented to demonstrate the appearances of a normally functioning, but rarely seen Ventriculo-Pleural CSF Shunt. Copyright (2000) The Australian and New Zealand Society of Nuclear Medicine Inc

  15. Pediatric ventriculoperitoneal shunts and their complications: An analysis

    Directory of Open Access Journals (Sweden)

    Nitin Agarwal

    2017-01-01

    Conclusion: With this retrospective review of complications of VP shunts, age at initial shunt insertion and the interval between the age of initial shunt placement and onset of complications were the most important patient-related predictors of shunt failure. The different predominant etiological factors responsible for early and late shunt failure were infective and mechanical complications, respectively.

  16. A wireless monitoring system for Hydrocephalus shunts.

    Science.gov (United States)

    Narayanaswamy, A; Nourani, M; Tamil, L; Bianco, S

    2015-08-01

    Patients with Hydrocephalus are usually treated by diverting the excess Cerebrospinal Fluid (CSF) to other parts of the body using shunts. More than 40 percentage of shunts implanted fail within the first two years. Obstruction in the shunts is one of the major causes of failure (45 percent) and the detection of obstruction reduces the complexity of the revision surgery. This paper describes a proposed wireless monitoring system for clog detection and flow measurement in shunts. A prototype was built using multiple pressure sensors along the shunt catheters for sensing the location of clog and flow rate. Regular monitoring of flow rates can be used to adjust the valve in the shunt to prevent over drainage or under drainage of CSF. The accuracy of the flow measurement is more than 90 percent.

  17. Arterioportal shunts on dynamic computed tomography

    International Nuclear Information System (INIS)

    Nakayama, T.; Hiyama, Y.; Ohnishi, K.; Tsuchiya, S.; Kohno, K.; Nakajima, Y.; Okuda, K.

    1983-01-01

    Thirty-two patients, 20 with hepatocelluar carcinoma and 12 with liver cirrhosis, were examined by dynamic computed tomography (CT) using intravenous bolus injection of contrast medium and by celiac angiography. Dynamic CT disclosed arterioportal shunting in four cases of hepatocellular carcinoma and in one of cirrhosis. In three of the former, the arterioportal shunt was adjacent to a mass lesion on CT, suggesting tumor invasion into the portal branch. In one with hepatocellular carcinoma, the shunt was remote from the mass. In the case with cirrhosis, there was no mass. In these last two cases, the shunt might have been caused by prior percutaneous needle puncture. In another case of hepatocellular carcinoma, celiac angiography but not CT demonstrated an arterioportal shunt. Thus, dynamic CT was diagnostic in five of six cases of arteriographically demonstrated arterioportal shunts

  18. Bidirectional optical rotation of cells

    Directory of Open Access Journals (Sweden)

    Jiyi Wu

    2017-08-01

    Full Text Available Precise and controlled rotation manipulation of cells is extremely important in biological applications and biomedical studies. Particularly, bidirectional rotation manipulation of a single or multiple cells is a challenge for cell tomography and analysis. In this paper, we report an optical method that is capable of bidirectional rotation manipulation of a single or multiple cells. By launching a laser beam at 980 nm into dual-beam tapered fibers, a single or multiple cells in solutions can be trapped and rotated bidirectionally under the action of optical forces. Moreover, the rotational behavior can be controlled by altering the relative distance between the two fibers and the input optical power. Experimental results were interpreted by numerical simulations.

  19. The somatic shunt cable model for neurons.

    OpenAIRE

    Durand, D

    1984-01-01

    The derivation of the equations for an electrical model of nerve cells is presented. The model consists of an equivalent cylinder, a lumped somatic impedance, and a variable shunt at the soma. This shunt was introduced to take into account the fast voltage decays observed following the injections of current pulses in some motoneurons and hippocampal granule cells that could not be explained by existing models. The shunt can be interpreted either by penetration damage with the electrode or by ...

  20. Bidirectional reachability-based modules

    CSIR Research Space (South Africa)

    Nortje, R

    2011-07-01

    Full Text Available The authors introduce an algorithm for MinA extraction in EL based on bidirectional reachability. They obtain a significant reduction in the size of modules extracted at almost no additional cost to that of extracting standard reachability...

  1. Shunt protection for superconducting Maglev magnets

    Energy Technology Data Exchange (ETDEWEB)

    Atherton, D L [Queen' s Univ., Kingston, Ontario (Canada). Dept. of Physics

    1979-09-01

    Closely coupled, short-circuited shunt coils are proposed for quench protection of superconducting Maglev magnets which use high resistance, matrix composite conductors. It is shown that, by suitable design, the shunts can reduce induced ac losses and that the changing currents during magnet energization or vehicle lift off and landing can be tolerated.

  2. Shunt protection for superconducting Maglev magnets

    International Nuclear Information System (INIS)

    Atherton, D.L.

    1979-01-01

    Closely coupled, short-circuited shunt coils are proposed for quench protection of superconducting Maglev magnets which use high resistance, matrix composite conductors. It is shown that, by suitable design, the shunts can reduce induced ac losses and that the changing currents during magnet energization or vehicle lift off and landing can be tolerated. (author)

  3. 30 CFR 57.6401 - Shunting.

    Science.gov (United States)

    2010-07-01

    ... HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Explosives Electric Blasting-Surface and Underground § 57.6401 Shunting. Except during testing— (a) Electric detonators shall be kept shunted until connected to the blasting line or wired into a blasting round; (b) Wired rounds shall be...

  4. MR imaging of syringoperitoneal and syringosubarachnoid shunts

    International Nuclear Information System (INIS)

    Hasso, A.N.; Kucharczyk, W.; Mall, J.C.; Colombo, N.; Newton, T.H.; Norman, D.

    1986-01-01

    The authors utilized MR imaging for the evaluation of syringohydromelic shunt procedures in 16 patients. Four characteristic MR imaging findings were seen: ''tethering'' of the spinal cord posteriorly at the site of laminectomy and placement of the shunt tube distortion of the usual elliptical shape of the spinal cord at the site of the shunt, a ''snake-eyes'' appearance of the cord on transverse images which corresponded to the position of the shunt within or next to a collapsed syringohydromelic cavity, and a generous amount of subachnoid space surrounding the collapsed portion of the cavity. Occasionally the shunt could not be visualized on sagittal images but could be seen on transverse images. In the majority of cases, the MR imaging findings were sufficiently characteristic to warrant accurate diagnosis

  5. Ventriculoperitoneal shunt complications needing shunt revision in children: A review of 5 years of experience with 48 revisions

    Directory of Open Access Journals (Sweden)

    Rajendra K Ghritlaharey

    2012-01-01

    Full Text Available Background: The aim of this study was to review the management of ventriculoperitoneal (VP shunt complications in children. Patients and Methods: During the last 5 years (January 1, 2006 to December 31, 2010, 236 VP shunt operations were performed in children under 12 years of age; of these, 40 (16.94% developed shunt complications and those who underwent VP shunt revisions were studied. Results: This prospective study included 40 (28 boys and 12 girls children and required 48 shunt revisions. Complications following VP shunts that required shunt revisions were peritoneal catheter/peritoneal end malfunction (18, shunt/shunt tract infections (7, extrusion of peritoneal catheter through anus (5, ventricular catheter malfunction (4, cerebrospinal fluid (CSF leak from abdominal wound (4, shunt system failure (2, ventricular end/shunt displacement (2, CSF pseudocysts peritoneal cavity (2, extrusion of peritoneal catheter from neck, chest, abdominal scar and through umbilicus, one each. Four-fifth of these shunt complications occurred within 6 months of previous surgery. Surgical procedures done during shunt revisions in order of frequency were revision of peritoneal part of shunt (27, 56.25%, revision of entire shunt system (6, 12.5%, extra ventricular drainage and delayed re-shunt (5, 10.41%, shunt removal and delayed re-shunt (5, 10.41%, opposite side shunting (2, 4.16%, cysts excision and revision of peritoneal catheter (2, 4.16% and revision of ventricular catheter (1, 2.08%. The mortalities following VP shunt operations were 44 (18.64% and following shunt revisions were 4 (10%. Conclusions: VP shunt done for hydrocephalus in children is not only prone for complications and need for revision surgery but also associated with considerable mortality.

  6. Research progress in TIPS shunt dysfunction and recanalization

    Directory of Open Access Journals (Sweden)

    WANG Tingting

    2015-11-01

    Full Text Available Transjugular intrahepatic portosystemic shunt (TIPS is widely used in the treatment of cirrhotic portal hypertension and its associated complications. However, postoperative shunt dysfunction has been an important factor restricting the clinical application of TIPS. This article summarizes the use of shunt, the incidence of shunt dysfunction after TIPS, preventive measures and diagnostic methods for shunt dysfunction, and indications and techniques of shunt recanalization, in order to enhance our knowledge of shunt dysfunction and recanalization, which could further improve the efficacy of TIPS for cirrhotic portal hypertension.

  7. Primary ventriculoperitoneal shunting outcomes: a multicentre clinical audit for shunt infection and its risk factors.

    Science.gov (United States)

    Woo, P Ym; Wong, H T; Pu, J Ks; Wong, W K; Wong, L Yw; Lee, M Wy; Yam, K Y; Lui, W M; Poon, W S

    2016-10-01

    To determine the frequency of primary ventriculoperitoneal shunt infection among patients treated at neurosurgical centres of the Hospital Authority and to identify underlying risk factors. This multicentre historical cohort study included consecutive patients who underwent primary ventriculoperitoneal shunting at a Hospital Authority neurosurgery centre from 1 January 2009 to 31 December 2011. The primary endpoint was shunt infection, defined as: (1) the presence of cerebrospinal fluid or shunt hardware culture that yielded the pathogenic micro-organism with associated compatible symptoms and signs of central nervous system infection or shunt malfunction; or (2) surgical incision site infection requiring shunt reinsertion (even in the absence of positive culture); or (3) intraperitoneal pseudocyst formation (even in the absence of positive culture). Secondary endpoints were shunt malfunction, defined as unsatisfactory cerebrospinal fluid drainage that required shunt reinsertion, and 30-day mortality. A primary ventriculoperitoneal shunt was inserted in 538 patients during the study period. The mean age of patients was 48 years (range, 13-88 years) with a male-to-female ratio of 1:1. Aneurysmal subarachnoid haemorrhage was the most common aetiology (n=169, 31%) followed by intracranial tumour (n=164, 30%), central nervous system infection (n=42, 8%), and traumatic brain injury (n=27, 5%). The mean operating time was 75 (standard deviation, 29) minutes. Shunt reinsertion and infection rates were 16% (n=87) and 7% (n=36), respectively. The most common cause for shunt reinsertion was malfunction followed by shunt infection. Independent predictors for shunt infection were: traumatic brain injury (adjusted odds ratio=6.2; 95% confidence interval, 2.3-16.8), emergency shunting (2.3; 1.0-5.1), and prophylactic vancomycin as the sole antibiotic (3.4; 1.1-11.0). The 30-day all-cause mortality was 6% and none were directly procedure-related. This is the first Hong Kong

  8. Idiopathic intracranial hypertension: lumboperitoneal shunts versus ventriculoperitoneal shunts--case series and literature review.

    LENUS (Irish Health Repository)

    Abubaker, Khalid

    2012-02-01

    OBJECTIVES: Idiopathic intracranial hypertension (IIH) is an uncommon but important cause of headache that can lead to visual loss. This study was undertaken to review our experience in the treatment of IIH by neuronavigation-assisted ventriculoperitoneal (VP) shunts with programmable valves as compared to lumboperitoneal (LP) shunts. METHODS: A retrospective chart review was conducted on 25 patients treated for IIH between 2001 and 2009. Age, sex, clinical presentation, methods of treatment and failure rates were recorded. RESULTS: Seventy-two per cent were treated initially with LP shunts. Failure rate was 11% in this group. Neuronavigation-assisted VP shunts were used to treat 28%. In this group, the failure rate was 14%. CONCLUSION: Our experience indicates that both LP shunts and VP shuts are effective in controlling all the clinical manifestations of IIH in the immediate postoperative period. Failure rates are slightly higher for VP shunts (14%) than LP shunts (11%). However, revision rates are higher with LP shunts (60%) than with VP shunts (30%).

  9. Congenital portosystemic shunts with and without gastrointestinal bleeding - case series

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Ying; Chen, Jun; Chen, Qi; Ji, Min; Pa, Mier; Qiao, Zhongwei [Children' s Hospital of Fudan University, Department of Radiology, Shanghai (China); Zhu, Hui [Fudan University Shanghai Cancer Center, Department of Radiology, Shanghai (China); Zheng, Shan [Children' s Hospital of Fudan University, Department of Surgery, Shanghai (China)

    2015-12-15

    The clinical presentation of congenital portosystemic shunt is variable and gastrointestinal bleeding is an uncommon presentation. To describe the imaging features of congenital portosystemic shunt as it presented in 11 children with (n = 6) and without gastrointestinal bleeding (n = 5). We performed a retrospective study on a clinical and imaging dataset of 11 children diagnosed with congenital portosystemic shunt. A total of 11 children with congenital portosystemic shunt were included in this study, 7 with extrahepatic portosystemic shunts and 4 with intrahepatic portosystemic shunts. Six patients with gastrointestinal bleeding had an extrahepatic portosystemic shunt, and the imaging results showed that the shunts originated from the splenomesenteric junction (n = 5) or splenic vein (n = 1) and connected to the internal iliac vein. Among the five cases of congenital portosystemic shunt without gastrointestinal bleeding, one case was an extrahepatic portosystemic shunt and the other four were intrahepatic portosystemic shunts. Most congenital portosystemic shunt patients with gastrointestinal bleeding had a shunt that drained portal blood into the iliac vein via an inferior mesenteric vein. This type of shunt was uncommon, but the concomitant rate of gastrointestinal bleeding with this type of shunt was high. (orig.)

  10. Resonant Electromagnetic Shunt Damping of Flexible Structures

    DEFF Research Database (Denmark)

    Høgsberg, Jan Becker

    2016-01-01

    Electromagnetic transducers convert mechanical energy to electrical energy and vice versa. Effective passive vibration damping of flexible structures can therefore be introduced by shunting with an accurately calibrated resonant electrical network thatcontains a capacitor to create the desired...

  11. Endoscopic third ventriculostomy versus ventriculoperitoneal shunt ...

    African Journals Online (AJOL)

    Patients' medical records, operative notes, and neural tube database records were used to complete a structured questionnaire. The difference in ... likely after 6 months. Keywords: obstructive hydrocephalus; endoscopic third ventriculostomy; ventriculoperitoneal shunt; children; paediatric surgery; neurosurgery; Ethiopia ...

  12. Nonconventional mesocaval prosthetic shunt interposition in ...

    African Journals Online (AJOL)

    years demonstrates shunt patency and normal development ... However, the child's condition and growth ... The child has satisfactory weight and growth gain. (40kg .... infants and toddlers: replacement with decellularized branched pulmonary.

  13. Surgical approach for systemic-pulmonary shunt in neonates with functionally univentricular heart: comparison between sternotomy and thoracotomy.

    Science.gov (United States)

    Sasaki, Takashi; Takeda, Yuko; Ohnakatomi, Yasuko; Asou, Toshihide

    2016-09-01

    The preferred surgical approach for systemic-pulmonary shunts has changed from thoracotomy to sternotomy in our institution, to concomitantly manage the ductus arteriosus during surgery. The purpose of this study was to compare the outcomes of systemic-pulmonary shunts for neonates with functionally univentricular hearts based on surgical approach. Fifty-two neonates with functionally univentricular hearts underwent systemic-pulmonary shunt via sternotomy (n = 28) or thoracotomy (n = 24). Patient characteristics, achievement rates of right heart bypass, and survival rates were compared for the different approaches. Prenatal diagnosis was made more common in the sternotomy group (p = 0.006). The shunt was placed more centrally in the sternotomy group. The ductus arteriosus was ligated or banded in most patients in the sternotomy group (26/28) and in a few patients in the thoracotomy group (6/24). Frequency of ductal management in the early postoperative phase was not different between the groups (21 vs 25 %), but three new incisions had to be made in the thoracotomy group. No differences were seen in the achievement rates of bidirectional cavopulmonary shunts (86 vs 87 % at 10 months of age) and total cavopulmonary connection (81 vs 81 % at 2 years of age), or in the survival rates (92 vs 96 % at 8 years). There were no differences in short- and long-term outcomes between the groups. The sternotomy approach might be preferable in the current era of prenatal diagnosis, to allow simultaneous duct management during systemic-pulmonary shunt surgery, particularly in patients with large ducts associated with functionally univentricular hearts.

  14. Cell shunt resistance and photovoltaic module performance

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, T.J.; Basso, T.S.; Rummel, S.R. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    Shunt resistance of cells in photovoltaic modules can affect module power output and could indicate flawed manufacturing processes and reliability problems. The authors describe a two-terminal diagnostic method to directly measure the shunt resistance of individual cells in a series-connected module non-intrusively, without deencapsulation. Peak power efficiency vs. light intensity was measured on a 12-cell, series-connected, single crystalline module having relatively high cell shunt resistances. The module was remeasured with 0.5-, 1-, and 2-ohm resistors attached across each cell to simulate shunt resistances of several emerging technologies. Peak power efficiencies decreased dramatically at lower light levels. Using the PSpice circuit simulator, the authors verified that cell shunt and series resistances can indeed be responsible for the observed peak power efficiency vs. intensity behavior. The authors discuss the effect of basic cell diode parameters, i.e., shunt resistance, series resistance, and recombination losses, on PV module performance as a function of light intensity.

  15. Endoscopic Third Ventriculostomy in Previously Shunted Children

    Directory of Open Access Journals (Sweden)

    Eva Brichtova

    2013-01-01

    Full Text Available Endoscopic third ventriculostomy (ETV is a routine and safe procedure for therapy of obstructive hydrocephalus. The aim of our study is to evaluate ETV success rate in therapy of obstructive hydrocephalus in pediatric patients formerly treated by ventriculoperitoneal (V-P shunt implantation. From 2001 till 2011, ETV was performed in 42 patients with former V-P drainage implantation. In all patients, the obstruction in aqueduct or outflow parts of the fourth ventricle was proved by MRI. During the surgery, V-P shunt was clipped and ETV was performed. In case of favourable clinical state and MRI functional stoma, the V-P shunt has been removed 3 months after ETV. These patients with V-P shunt possible removing were evaluated as successful. In our group of 42 patients we were successful in 29 patients (69%. There were two serious complications (4.7%—one patient died 2.5 years and one patient died 1 year after surgery in consequence of delayed ETV failure. ETV is the method of choice in obstructive hydrocephalus even in patients with former V-P shunt implantation. In case of acute or scheduled V-P shunt surgical revision, MRI is feasible, and if ventricular system obstruction is diagnosed, the hydrocephalus may be solved endoscopically.

  16. Idiopathic intracranial hypertension: lumboperitoneal shunts versus ventriculoperitoneal shunts--case series and literature review.

    LENUS (Irish Health Repository)

    Abubaker, Khalid

    2011-02-01

    Idiopathic intracranial hypertension (IIH) is an uncommon but important cause of headache that can lead to visual loss. This study was undertaken to review our experience in the treatment of IIH by neuronavigation-assisted ventriculoperitoneal (VP) shunts with programmable valves as compared to lumboperitoneal (LP) shunts.

  17. GABA Shunt in Durum Wheat

    Directory of Open Access Journals (Sweden)

    Petronia Carillo

    2018-02-01

    Full Text Available Plant responses to salinity are complex, especially when combined with other stresses, and involve many changes in gene expression and metabolic fluxes. Until now, plant stress studies have been mainly dealt only with a single stress approach. However, plants exposed to multiple stresses at the same time, a combinatorial approach reflecting real-world scenarios, show tailored responses completely different from the response to the individual stresses, due to the stress-related plasticity of plant genome and to specific metabolic modifications. In this view, recently it has been found that γ-aminobutyric acid (GABA but not glycine betaine (GB is accumulated in durum wheat plants under salinity only when it is combined with high nitrate and high light. In these conditions, plants show lower reactive oxygen species levels and higher photosynthetic efficiency than plants under salinity at low light. This is certainly relevant because the most of drought or salinity studies performed on cereal seedlings have been done in growth chambers under controlled culture conditions and artificial lighting set at low light. However, it is very difficult to interpret these data. To unravel the reason of GABA accumulation and its possible mode of action, in this review, all possible roles for GABA shunt under stress are considered, and an additional mechanism of action triggered by salinity and high light suggested.

  18. Portal hypertension: A critical appraisal of shunt procedures with emphasis on distal splenorenal shunt in children

    Directory of Open Access Journals (Sweden)

    Nitin Sharma

    2014-01-01

    Full Text Available Background: Extrahepatic portal venous obstruction (EHPVO is the most common cause of pediatric portal hypertension. We analyzed the investigative protocol and results of portosystemic shunts in this group of patients. Materials and Methods: A total of 40 consecutive children aged below 12 years operated with a diagnosis of extra-hepatic portal hypertension formed the study group. Historical data and clinical data were collected. All patients underwent upper gastrointestinal endoscopy, ultrasound Doppler and computed tomographic portogram pre-operatively and post-operatively. Results with respect to shunt patency, hypersplenism and efficacy of different radiological investigations were collected. Results: A total of 40 patients, 28 boys and 12 girls constituted the study group. Lienorenal shunt (LRS was performed in 14 patients; distal splenorenal shunt in 21 patients and side-to-side lienorenal shunt in 4 patients, inferior mesenteric renal shunt was performed in 1 patient. Follow-up ranged from 36 to 70 months. At a minimum follow-up of 3 years, 32 (80% patients were found to have patent shunts. Patent shunts could be visualized in 30/32 patients with computer tomographic portogram (CTP and 28/32 with ultrasound. Varices regressed completely in 26/32 patients and in the rest incomplete regression was seen. Spleen completely regressed in 19/25 patients. Hypersplenism resolved in all patients with patent shunts. Conclusions: Portosystemic shunting in children with EHPVO is a viable option. While long-term cure rates are comparable with sclerotherapy, repeated hospital visits are reduced with one time surgery. Pre-operative and post-operative assessment can be performed with complimentary use of ultrasound, CTP and endoscopy.

  19. Simulation model for port shunting yards

    Science.gov (United States)

    Rusca, A.; Popa, M.; Rosca, E.; Rosca, M.; Dragu, V.; Rusca, F.

    2016-08-01

    Sea ports are important nodes in the supply chain, joining two high capacity transport modes: rail and maritime transport. The huge cargo flows transiting port requires high capacity construction and installation such as berths, large capacity cranes, respectively shunting yards. However, the port shunting yards specificity raises several problems such as: limited access since these are terminus stations for rail network, the in-output of large transit flows of cargo relatively to the scarcity of the departure/arrival of a ship, as well as limited land availability for implementing solutions to serve these flows. It is necessary to identify technological solutions that lead to an answer to these problems. The paper proposed a simulation model developed with ARENA computer simulation software suitable for shunting yards which serve sea ports with access to the rail network. Are investigates the principal aspects of shunting yards and adequate measures to increase their transit capacity. The operation capacity for shunting yards sub-system is assessed taking in consideration the required operating standards and the measure of performance (e.g. waiting time for freight wagons, number of railway line in station, storage area, etc.) of the railway station are computed. The conclusion and results, drawn from simulation, help transports and logistics specialists to test the proposals for improving the port management.

  20. Balanced calibration of resonant shunt circuits for piezoelectric vibration control

    DEFF Research Database (Denmark)

    Høgsberg, Jan; Krenk, Steen

    2012-01-01

    Shunting of piezoelectric transducers and suitable electric circuits constitutes an effective passive approach to resonant vibration damping of structures. Most common design concepts for resonant resistor-inductor (RL) shunt circuits rely on either maximization of the attainable modal damping...

  1. Coupling slots without shunt impedance drop

    International Nuclear Information System (INIS)

    Balleyguier, P.

    1996-01-01

    It is well known that coupling slots between adjacent cells in a π-mode structure reduce shunt impedance per unit length with respect to single cell cavities. To design optimized coupling slots, one has to answer the following question: for a given coupling factor, what shape, dimension, position and number of slots lead to the lowest shunt impedance drop? A numerical study using the 3D code MAFIA has been carried out. The aim was to design the 352 MHz cavities for the high intensity proton accelerator of the TRISPAL project. The result is an unexpected set of four 'petal' slots. Such slots should lead to a quasi-negligible drop in shunt impedance: about -1% on average, for particle velocity from 0.4 c to 0.8 c. (author)

  2. Bidirectional waveguide coupling with plasmonic Fano nanoantennas

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Rui; Decker, Manuel, E-mail: manuel.decker@anu.edu.au; Staude, Isabelle; Neshev, Dragomir N.; Kivshar, Yuri S. [Nonlinear Physics Centre and Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS), Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia)

    2014-08-04

    We introduce the concept of a bidirectional, compact single-element Fano nanoantenna that allows for directional coupling of light in opposite directions of a high-index dielectric waveguide for two different operation wavelengths. We utilize a Fano resonance to tailor the radiation phases of a gold nanodisk and a nanoslit that is inscribed into the nanodisk to realize bidirectional scattering. We show that this Fano nanoantenna operates as a bidirectional waveguide coupler at telecommunication wavelengths and, thus, is ideally suitable for integrated wavelength-selective light demultiplexing.

  3. Distal splenorenal shunt with partial spleen resection

    Directory of Open Access Journals (Sweden)

    Gajin Predrag

    2007-01-01

    Full Text Available Introduction: Hypersplenism is a common complication of portal hypertension. Cytopenia in hypersplenism is predominantly caused by splenomegaly. Distal splenorenal shunt (Warren with partial spleen resection is an original surgical technique that regulates cytopenia by reduction of the enlarged spleen. Objective. The aim of our study was to present the advantages of distal splenorenal shunt (Warren with partial spleen resection comparing morbidity and mortality in a group of patients treated by distal splenorenal shunt with partial spleen resection with a group of patients treated only by a distal splenorenal shunt. Method. From 1995 to 2003, 41 patients with portal hypertension were surgically treated due to hypersplenism and oesophageal varices. The first group consisted of 20 patients (11 male, mean age 42.3 years who were treated by distal splenorenal shunt with partial spleen resection. The second group consisted of 21 patients (13 male, mean age 49.4 years that were treated by distal splenorenal shunt only. All patients underwent endoscopy and assessment of oesophageal varices. The size of the spleen was evaluated by ultrasound, CT or by scintigraphy. Angiography was performed in all patients. The platelet and white blood cell count and haemoglobin level were registered. Postoperatively, we noted blood transfusion, complications and total hospital stay. Follow-up period was 12 months, with first checkup after one month. Results In the first group, only one patient had splenomegaly postoperatively (5%, while in the second group there were 13 patients with splenomegaly (68%. Before surgery, the mean platelet count in the first group was 51.6±18.3x109/l, to 118.6±25.4x109/l postoperatively. The mean platelet count in the second group was 67.6±22.8x109/l, to 87.8±32.1x109/l postoperatively. Concerning postoperative splenomegaly, statistically significant difference was noted between the first and the second group (p<0.05. Comparing the

  4. Biophysical shunt theory for neuropsychopathology: Part I.

    Science.gov (United States)

    Naisberg, Y; Avnon, M; Weizman, A

    1995-11-01

    We present a new model of the origin of schizophrenia based on biophysical ionic shunts in neuronal (electrical) pathways. Microstructural and molecular evidence is presented for the way in which changes in the neuronal membrane ionic channels may facilitate membrane property rearrangement, leading to a change in the density and composition of the ion channel charge which in turn causes a change in ionic flow orientation and distribution. We suggest that, under abnormal conditions, ionic flow shunts are created which redirect the biophysical collateral neuronal (electrical) pathways, resulting in psychiatric signs and symptoms. This model is complementary to the biological basis of schizophrenia.

  5. Relationship of cerebral blood flow to aortic-to-pulmonary collateral/shunt flow in single ventricles

    Science.gov (United States)

    Fogel, Mark A; Li, Christine; Wilson, Felice; Pawlowski, Tom; Nicolson, Susan C; Montenegro, Lisa M; Berenstein, Laura Diaz; Spray, Thomas L; Gaynor, J William; Fuller, Stephanie; Keller, Marc S; Harris, Matthew A; Whitehead, Kevin K; Clancy, Robert; Elci, Okan; Bethel, Jim; Vossough, Arastoo; Licht, Daniel J

    2016-01-01

    Objective Patients with single ventricle can develop aortic-to-pulmonary collaterals (APCs). Along with systemic-to-pulmonary artery shunts, these structures represent a direct pathway from systemic to pulmonary circulations, and may limit cerebral blood flow (CBF). This study investigated the relationship between CBF and APC flow on room air and in hypercarbia, which increases CBF in patients with single ventricle. Methods 106 consecutive patients with single ventricle underwent 118 cardiac magnetic resonance (CMR) scans in this cross-sectional study; 34 prior to bidirectional Glenn (BDG) (0.50±0.30 years old), 50 prior to Fontan (3.19±1.03 years old) and 34 3–9 months after Fontan (3.98±1.39 years old). Velocity mapping measured flows in the aorta, cavae and jugular veins. Analysis of variance (ANOVA) and multiple linear regression were used. Significance was p<0.05. Results A strong inverse correlation was noted between CBF and APC/shunt both on room air and with hypercarbia whether CBF was indexed to aortic flow or body surface area, independent of age, cardiopulmonary bypass time, Po2 and Pco2 (R=−0.67–−0.70 for all patients on room air, p<0.01 and R=−0.49–−0.90 in hypercarbia, p<0.01). Correlations were not different between surgical stages. CBF was lower, and APCs/shunt flow was higher prior to BDG than in other stages. Conclusions There is a strong inverse relationship between CBF and APC/shunt flow in patients with single ventricle throughout surgical reconstruction on room air and in hypercarbia independent of other factors. We speculate that APC/shunt flow may have a negative impact on cerebral development and neurodevelopmental outcome. Interventions on APC may modify CBF, holding out the prospect for improving neurodevelopmental trajectory. Trial Registration Number NCT02135081. PMID:26048877

  6. Genetic and Functional Analysis of Congenital Portosystemic Shunts in Dogs

    NARCIS (Netherlands)

    van den Bossche, L.

    2017-01-01

    The general aim of this thesis was to gain further insight into the pathogenesis of congenital portosystemic shunts (CPSS), elucidate mechanisms involved in the pathophysiology of CPSS, and explore predictors of recovery after surgical ligation of the shunt. For intrahepatic portosystemic shunts

  7. Constrained bidirectional propagation and stroke segmentation

    Energy Technology Data Exchange (ETDEWEB)

    Mori, S; Gillespie, W; Suen, C Y

    1983-03-01

    A new method for decomposing a complex figure into its constituent strokes is described. This method, based on constrained bidirectional propagation, is suitable for parallel processing. Examples of its application to the segmentation of Chinese characters are presented. 9 references.

  8. Image Captioning with Deep Bidirectional LSTMs

    OpenAIRE

    Wang, Cheng; Yang, Haojin; Bartz, Christian; Meinel, Christoph

    2016-01-01

    This work presents an end-to-end trainable deep bidirectional LSTM (Long-Short Term Memory) model for image captioning. Our model builds on a deep convolutional neural network (CNN) and two separate LSTM networks. It is capable of learning long term visual-language interactions by making use of history and future context information at high level semantic space. Two novel deep bidirectional variant models, in which we increase the depth of nonlinearity transition in different way, are propose...

  9. Autologous patch graft in tube shunt surgery.

    Science.gov (United States)

    Aslanides, I M; Spaeth, G L; Schmidt, C M; Lanzl, I M; Gandham, S B

    1999-10-01

    To evaluate an alternate method of covering the subconjunctival portion of the tube in aqueous shunt surgery. Evidence of tube erosion, graft-related infection, graft melting, or other associated intraocular complications were evaluated. A retrospective study of 16 patients (17 eyes) who underwent tube shunt surgery at Wills Eye Hospital between July 1991 and October 1996 was conducted. An autologous either "free" or "rotating" scleral lamellar graft was created to cover the subconjunctival portion of the tube shunt. All patients were evaluated for at least 6 months, with a mean follow-up of 14.8 months (range 6-62 months). All eyes tolerated the autologous graft well, with no clinical evidence of tube erosion, or graft-related or intraocular complications. Autologous patch graft in tube shunt surgery appears--in selected cases--to be an effective, safe and inexpensive surgical alternative to allogenic graft materials. It also offers ease of availability, and eliminates the risk of transmitting infectious disease.

  10. ARTIFICIAL SHUNTING OF CEREBROSPINAL-FLUID

    NARCIS (Netherlands)

    HOEKSTRA, A

    A compact three-stage shunt valve system (Orbis SigmaTM Valve) which operates as a flow regulator within certain differential pressure values has been clinically evaluated in the treatment of hydrocephalus. Clinical trials were performed in 134 cases, covering 128 patients aged from 1 day to 79

  11. Ventriculoperitoneal shunt infection caused by Bifidobacterium breve.

    Science.gov (United States)

    Suwantarat, Nuntra; Romagnoli, Mark; Wakefield, Teresa; Carroll, Karen C

    2014-08-01

    Bifidobacterium breve is a rare cause of human infections. Previously, bacteremia and meningitis caused by this organism linked to probiotic use have been reported in a neonate. We report the first case of a ventriculoperitoneal shunt infection caused by B. breve in an adult without a history of probiotic use. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Complications of ventriculoperitoneal shunt in hydrocephalic children

    African Journals Online (AJOL)

    These children were treated at the Department of Pediatric Surgery, Dr. Behc¸et Uz Children's Hospital, and at the Department of Neurosurgery, Tepecik Training Hospital. Management of these patients with special emphasis on the literature pertaining to the migration of shunt catheters into the scrotum is reviewed and ...

  13. Power Quality Improvement Using an Enhanced Network-Side-Shunt-Connected Dynamic Voltage Restorer

    Science.gov (United States)

    Fereidouni, Alireza; Masoum, Mohammad A. S.; Moghbel, Moayed

    2015-10-01

    Among the four basic dynamic voltage restorer (DVR) topologies, the network-side shunt-connected DVR (NSSC-DVR) has a relatively poor performance and is investigated in this paper. A new configuration is proposed and implemented for NSSC-DVR to enhance its performance in compensating (un)symmetrical deep and long voltage sags and mitigate voltage harmonics. The enhanced NSSC-DVR model includes a three-phase half-bridge semi-controlled network-side-shunt-connected rectifier and a three-phase full-bridge series-connected inverter implemented with a back-to-back configuration through a bidirectional buck-boost converter. The network-side-shunt-connected rectifier is employed to inject/draw the required energy by NSSC-DVR to restore the load voltage to its pre-fault value under sag/swell conditions. The buck-boost converter is responsible for maintaining the DC-link voltage of the series-connected inverter at its designated value in order to improve the NSSC-DVR capability in compensating deep and long voltage sags/swells. The full-bridge series-connected inverter permits to compensate unbalance voltage sags containing zero-sequence component. The harmonic compensation of the load voltage is achieved by extracting harmonics from the distorted network voltage using an artificial neural network (ANN) method called adaptive linear neuron (Adaline) strategy. Detailed simulations are performed by SIMULINK/MATLAB software for six case studies to verify the highly robustness of the proposed NSSC-DVR model under various conditions.

  14. Pathological Predictors of Shunt Stenosis and Hepatic Encephalopathy after Transjugular Intrahepatic Portosystemic Shunt

    Directory of Open Access Journals (Sweden)

    Fuliang He

    2016-01-01

    Full Text Available Background. Transjugular intrahepatic portosystemic shunt (TIPS is an artificial channel from the portal vein to the hepatic vein or vena cava for controlling portal vein hypertension. The major drawbacks of TIPS are shunt stenosis and hepatic encephalopathy (HE; previous studies showed that post-TIPS shunt stenosis and HE might be correlated with the pathological features of the liver tissues. Therefore, we analyzed the pathological predictors for clinical outcome, to determine the risk factors for shunt stenosis and HE after TIPS. Methods. We recruited 361 patients who suffered from portal hypertension symptoms and were treated with TIPS from January 2009 to December 2012. Results. Multivariate logistic regression analysis showed that the risk of shunt stenosis was increased with more severe inflammation in the liver tissue (OR, 2.864; 95% CI: 1.466–5.592; P=0.002, HE comorbidity (OR, 6.266; 95% CI, 3.141–12.501; P<0.001, or higher MELD score (95% CI, 1.298–1.731; P<0.001. Higher risk of HE was associated with shunt stenosis comorbidity (OR, 6.266; 95% CI, 3.141–12.501; P<0.001, higher stage of the liver fibrosis (OR, 2.431; 95% CI, 1.355–4.359; P=0.003, and higher MELD score (95% CI, 1.711–2.406; P<0.001. Conclusion. The pathological features can predict individual susceptibility to shunt stenosis and HE.

  15. Effect of electromagnetic navigated ventriculoperitoneal shunt placement on failure rates.

    Science.gov (United States)

    Jung, Nayoung; Kim, Dongwon

    2013-03-01

    To evaluate the effect of electromagnetic (EM) navigation system on ventriculoperitoneal (VP) shunt failure rate through comparing the result of standard shunt placement. All patients undergoing VP shunt from October 2007 to September 2010 were included in this retrospective study. The first group received shunt surgery using EM navigation. The second group had catheters inserted using manual method with anatomical landmark. The relationship between proximal catheter position and shunt revision rate was evaluated using postoperative computed tomography by a 3-point scale. 1) Grade I; optimal position free-floating in cerebrospinal fluid, 2) Grade II; touching choroid or ventricular wall, 3) Grade III; tip within parenchyma. A total of 72 patients were participated, 27 with EM navigated shunts and 45 with standard shunts. Grade I was found in 25 patients from group 1 and 32 patients from group 2. Only 2 patients without use of navigation belonged to grade III. Proximal obstruction took place 7% in grade I, 15% in grade II and 100% in grade III. Shunt revision occurred in 11% of group 1 and 31% of group 2. Compared in terms of proximal catheter position, there was growing trend of revision rate according to increase of grade on each group. Although infection rate was similar between both groups, the result had no statistical meaning (p=0.905, chi-square test). The use of EM navigation in routine shunt surgery can eliminate poor shunt placement resulting in a dramatic reduction in failure rates.

  16. Ventriculosubgaleal shunts for posthemorrhagic hydrocephalus in premature infants.

    Science.gov (United States)

    Willis, Brian K; Kumar, Cherukuri Ravi; Wylen, Esther L; Nanda, Anil

    2005-01-01

    The early management of posthemorrhagic hydrocephalus in premature infants is challenging and controversial. These infants need a temporary cerebrospinal fluid (CSF) diversion procedure until they gain adequate weight, and the blood and protein levels in CSF are reasonably low before permanent shunt can be placed. Various options are available with their associated advantages and disadvantages. Ventriculosubgaleal shunts have been recommended as a more physiologic and less invasive means of achieving this goal. We have performed this procedure in 6 premature infants to evaluate their effectiveness and complications. Six consecutive premature infants with posthemorrhagic hydrocephalus underwent placement of ventriculosubgaleal shunts over a 1-year period of time. We reviewed their clinical and imaging progress to assess the ability of the shunt to control hydrocephalus and the complication rates. In all 6 patients, the ventriculosubgaleal shunt controlled the progression of hydrocephalus as assessed by clinical and imaging parameters. A permanent shunt was avoided in 1 patient (16.6%). However, 4 patients developed shunt infections, 1 involving the ventriculosubgaleal shunt itself, and 3 immediately after conversion to ventriculoperitoneal shunt. The total infection rate of the series was 66.6%. All infections were caused by staphylococcus species. There was only a 1% shunt infection rate in our institution for all nonventriculosubgaleal shunts during the same period of time. Placement of ventriculosubgaleal shunts for interim CSF diversion in neonates with posthemorrhagic hydrocephalus is effective as a temporary method of CSF diversion. However, our experience has shown that it is associated with a unacceptably high CSF infection rate. A potential cause for infection is CSF stasis just beneath the extremely thin skin of the premature infants, promoting colonization by skin flora. CSF sampling before conversion to a permanent shunt and replacement of the proximal

  17. Comparative analyses of bidirectional promoters in vertebrates

    Directory of Open Access Journals (Sweden)

    Taylor James

    2008-05-01

    Full Text Available Abstract Background Orthologous genes with deep phylogenetic histories are likely to retain similar regulatory features. In this report we utilize orthology assignments for pairs of genes co-regulated by bidirectional promoters to map the ancestral history of the promoter regions. Results Our mapping of bidirectional promoters from humans to fish shows that many such promoters emerged after the divergence of chickens and fish. Furthermore, annotations of promoters in deep phylogenies enable detection of missing data or assembly problems present in higher vertebrates. The functional importance of bidirectional promoters is indicated by selective pressure to maintain the arrangement of genes regulated by the promoter over long evolutionary time spans. Characteristics unique to bidirectional promoters are further elucidated using a technique for unsupervised classification, known as ESPERR. Conclusion Results of these analyses will aid in our understanding of the evolution of bidirectional promoters, including whether the regulation of two genes evolved as a consequence of their proximity or if function dictated their co-regulation.

  18. Hydrocephalus shunt technology: 20 years of experience from the Cambridge Shunt Evaluation Laboratory.

    Science.gov (United States)

    Chari, Aswin; Czosnyka, Marek; Richards, Hugh K; Pickard, John D; Czosnyka, Zofia H

    2014-03-01

    The Cambridge Shunt Evaluation Laboratory was established 20 years ago. This paper summarizes the findings of that laboratory for the clinician. Twenty-six models of valves have been tested long-term in the shunt laboratory according to the expanded International Organization for Standardization 7197 standard protocol. The majority of the valves had a nonphysiologically low hydrodynamic resistance (from 1.5 to 3 mm Hg/[ml/min]), which may result in overdrainage related to posture and during nocturnal cerebral vasogenic waves. A long distal catheter increases the resistance of these valves by 100%-200%. Drainage through valves without a siphon-preventing mechanism is very sensitive to body posture, which may result in grossly negative intracranial pressure. Siphon-preventing accessories offer a reasonable resistance to negative outlet pressure; however, accessories with membrane devices may be blocked by raised subcutaneous pressure. In adjustable valves, the settings may be changed by external magnetic fields of intensity above 40 mT (exceptions: ProGAV, Polaris, and Certas). Most of the magnetically adjustable valves produce large distortions on MRI studies. The behavior of a valve revealed during testing is of relevance to the surgeon and may not be adequately described in the manufacturer's product information. The results of shunt testing are helpful in many circumstances, such as the initial choice of shunt and the evaluation of the shunt when its dysfunction is suspected.

  19. Bidirectional Modulation of Recognition Memory.

    Science.gov (United States)

    Ho, Jonathan W; Poeta, Devon L; Jacobson, Tara K; Zolnik, Timothy A; Neske, Garrett T; Connors, Barry W; Burwell, Rebecca D

    2015-09-30

    Perirhinal cortex (PER) has a well established role in the familiarity-based recognition of individual items and objects. For example, animals and humans with perirhinal damage are unable to distinguish familiar from novel objects in recognition memory tasks. In the normal brain, perirhinal neurons respond to novelty and familiarity by increasing or decreasing firing rates. Recent work also implicates oscillatory activity in the low-beta and low-gamma frequency bands in sensory detection, perception, and recognition. Using optogenetic methods in a spontaneous object exploration (SOR) task, we altered recognition memory performance in rats. In the SOR task, normal rats preferentially explore novel images over familiar ones. We modulated exploratory behavior in this task by optically stimulating channelrhodopsin-expressing perirhinal neurons at various frequencies while rats looked at novel or familiar 2D images. Stimulation at 30-40 Hz during looking caused rats to treat a familiar image as if it were novel by increasing time looking at the image. Stimulation at 30-40 Hz was not effective in increasing exploration of novel images. Stimulation at 10-15 Hz caused animals to treat a novel image as familiar by decreasing time looking at the image, but did not affect looking times for images that were already familiar. We conclude that optical stimulation of PER at different frequencies can alter visual recognition memory bidirectionally. Significance statement: Recognition of novelty and familiarity are important for learning, memory, and decision making. Perirhinal cortex (PER) has a well established role in the familiarity-based recognition of individual items and objects, but how novelty and familiarity are encoded and transmitted in the brain is not known. Perirhinal neurons respond to novelty and familiarity by changing firing rates, but recent work suggests that brain oscillations may also be important for recognition. In this study, we showed that stimulation of

  20. Nitrogen heat pipe for cryocooler thermal shunt

    International Nuclear Information System (INIS)

    Prenger F.C.; Hill, D.D.; Daney, D.E.

    1996-01-01

    A nitrogen heat pipe was designed, built and tested for the purpose of providing a thermal shunt between the two stages of a Gifford-McMahan (GM) cryocooler during cooldown. The nitrogen heat pipe has an operating temperature range between 63 and 123 K. While the heat pipe is in this temperature range during the system cooldown, it acts as a thermal shunt between the first and second stage of the cryocooler. The heat pipe increases the heat transfer to the first stage of the cryocooler, thereby reducing the cooldown time of the system. When the heat pipe temperature drops below the triple point, the nitrogen working fluid freezes, effectively stopping the heat pipe operation. A small heat leak between cryocooler stages remains because of axial conduction along the heat pipe wall. As long as the heat pipe remains below 63 K, the heat pipe remains inactive. Heat pipe performance limits were measured and the optimum fluid charge was determined

  1. Prophylactic antibiotics in pediatric shunt surgery.

    Science.gov (United States)

    Biyani, N; Grisaru-Soen, G; Steinbok, P; Sgouros, S; Constantini, S

    2006-11-01

    The optimal antibiotic prophylaxis for pediatric shunt-related procedures is not clear. There is much inconsistency among different medical centers. This paper summarizes and analyzes the various prophylactic antibiotic regiments used for shunt-related surgeries at different pediatric neurosurgery centers in the world. A survey questionnaire was distributed through the Pediatric Neurosurgery list-server (an e-mail-based special interest group in pediatric neurosurgery). Forty-five completed questionnaires were received, one per medical center, primarily from pediatric neurosurgeons with the following geographic breakdown: 25 from North America, 13 from Europe, and 7 from Asia and other countries. All centers routinely administered prophylactic antibiotics for shunt-related procedures. The drugs of choice were first-generation cephalosporins (23), second-generation cephalosporins (10), naficillin/oxacillin (4), vancomycin (3), clindamycin (1), amoxicillin (1), and mixed protocols in three centers. The initial drug administration ("first dose") was: in the department before transfer to operating room (5), upon arrival to operating room (11), at induction of anesthesia (13), and at initial skin incision (16). The duration of antibiotic dosage also varied: single dose (13), 24-h administration (26), 48-h administration (2), and longer than 48 h in four centers. Two general tendencies were noted, common to the majority of participating centers. There was a general trend to modify antibiotic treatment protocol in "high-risk" populations. The second common theme noted in more than half of responding centers was the use of long-term antibiotic treatment for externalized devices (such as externalized shunts, external ventricular drains or lumbar drains), usually till the device was in place.

  2. The transjugular intrahepatic portosystemic shunt (TIPS)

    International Nuclear Information System (INIS)

    Owen, A.R.; Stanley, A.J.; Vijayananthan, A.; Moss, J.G.

    2009-01-01

    The creation of an intrahepatic portosystemic shunt via a transjugular approach (TIPS) is an interventional radiological procedure used to treat the complications of portal hypertension. TIPS insertion is principally indicated to prevent or arrest variceal bleeding when medical or endoscopic treatments fail, and in the management refractory ascites. This review discusses the development and execution of the technique, with focus on its clinical efficacy. Patient selection, imaging surveillance, revision techniques, and complications are also discussed.

  3. Train shunting at a workshop area

    DEFF Research Database (Denmark)

    Jacobsen, Per Munk; Pisinger, David

    2011-01-01

    We consider the problem of planning the shunting of train units at a railway workshop area. Before and after the maintenance check, a train unit is parked at a depository track. The problem is to schedule the trains to workshops and depot tracks in order to complete the repairs as soon as possibl....... It turns out, that both GLS and SA find within a few minutes solutions that are a few percent from the best MIP solution found....

  4. The transjugular intrahepatic portosystemic shunt (TIPS)

    Energy Technology Data Exchange (ETDEWEB)

    Owen, A.R. [Department of Radiology, Austin Health, Heidelberg, Melbourne (Australia)], E-mail: andrewowen@doctors.org.uk; Stanley, A.J. [Department of Gastroenterology, Glasgow Royal Infirmary, Glasgow (United Kingdom); Vijayananthan, A. [Department of Biomedical Imaging, University of Malaya, Kuala Lumpur (Malaysia); Moss, J.G. [Department of Radiology, Gartnavel General Hospital, Glasgow (United Kingdom)

    2009-07-15

    The creation of an intrahepatic portosystemic shunt via a transjugular approach (TIPS) is an interventional radiological procedure used to treat the complications of portal hypertension. TIPS insertion is principally indicated to prevent or arrest variceal bleeding when medical or endoscopic treatments fail, and in the management refractory ascites. This review discusses the development and execution of the technique, with focus on its clinical efficacy. Patient selection, imaging surveillance, revision techniques, and complications are also discussed.

  5. A follow-up study of neonatal interatrial shunt with echocardiography until twelve to fifteen months of age.

    Science.gov (United States)

    Ho, Chi-Lin; Jan, Sheng-Ling; Lin, Ming-Chih; Fu, Yun-Ching

    2008-12-01

    To assess the incidence and natural history of full-term neonates with interatrial shunt (IAS). A follow-up study of 1389 neonates who received screening echocardiography between 2003 and 2006. Babies with IAS at 2 to 4 days of life underwent follow-up echocardiography at 2 to 4 months, 6 to 9 months and 12 to 15 months of age until closure of IAS. The ratio of IAS was 68.3% initially. No significant demographic differences were identified between infants with and without initial IAS. Among 949 neonates with initial IAS, 84.5% infants had a left-to-right interatrial shunt, 13.5% had bidirectional shunt and 2% had predominantly right-to-left shunt. The persistence rate of IAS at 12 to 15 months of age was 3.8% (44/1166). The initial size of IAS ranged from 1.2 to 7.7mm (4.3+/-1.1 mm) detected by color Doppler flow mapping and cases were divided into three groups: small ( or =8 mm). There were 74.6% infants in the small group and 25.4% in the medium group initially. The neonates in the initial small group would always see their IAS close or else they would remain in the small group. Those in the final medium and large size groups always came from the initial medium group. The late closure rate of IAS was 93.9% of infants with initial IAS. The closure curves of initial small and medium sized groups were significantly different, and their late closure rates were 95.1% and 90.4%, respectively. IAS was very common during early neonatal stage, but most cases would close after 1 year. The late closure rate of initial IAS was different if using a cutpoint of 5 mm.

  6. A bidirectional shape memory alloy folding actuator

    International Nuclear Information System (INIS)

    Paik, Jamie K; Wood, Robert J

    2012-01-01

    This paper presents a low-profile bidirectional folding actuator based on annealed shape memory alloy sheets applicable for meso- and microscale systems. Despite the advantages of shape memory alloys—high strain, silent operation, and mechanical simplicity—their application is often limited to unidirectional operation. We present a bidirectional folding actuator that produces two opposing 180° motions. A laser-patterned nickel alloy (Inconel 600) heater localizes actuation to the folding sections. The actuator has a thin ( < 1 mm) profile, making it appropriate for use in robotic origami. Various design parameters and fabrication variants are described and experimentally explored in the actuator prototype. (paper)

  7. Bidirectional ventricular tachycardia of unknown etiology

    International Nuclear Information System (INIS)

    Ali, M.; Khan, J.A.; Masood, T.; Shamsi, F.; Dero, M.H.; Khan, S.

    2013-01-01

    A 45 years old male presented to the emergency department with palpitations, headache and apprehension. His electrocardiogram revealed bidirectional ventricular tachycardia. He remained vitally stable and responded to intravenous beta-blocker. Initially digitalis toxicity was suspected but history was negative for digitalis intake. The cause remained unidentified in patient despite detailed investigations. During a short follow-up (of 6 months) he remained asymptomatic and no cause was further identified during this period. Some other unseen causes of bidirectional ventricular tachycardia need to be explored. (author)

  8. Management of Transjugular Intrahepatic Portosystemic Shunt (TIPS)-associated Refractory Hepatic Encephalopathy by Shunt Reduction Using the Parallel Technique: Outcomes of a Retrospective Case Series

    International Nuclear Information System (INIS)

    Cookson, Daniel T.; Zaman, Zubayr; Gordon-Smith, James; Ireland, Hamish M.; Hayes, Peter C.

    2011-01-01

    Purpose: To investigate the reproducibility and technical and clinical success of the parallel technique of transjugular intrahepatic portosystemic shunt (TIPS) reduction in the management of refractory hepatic encephalopathy (HE). Materials and Methods: A 10-mm-diameter self-expanding stent graft and a 5–6-mm-diameter balloon-expandable stent were placed in parallel inside the existing TIPS in 8 patients via a dual unilateral transjugular approach. Changes in portosystemic pressure gradient and HE grade were used as primary end points. Results: TIPS reduction was technically successful in all patients. Mean ± standard deviation portosystemic pressure gradient before and after shunt reduction was 4.9 ± 3.6 mmHg (range, 0–12 mmHg) and 10.5 ± 3.9 mmHg (range, 6–18 mmHg). Duration of follow-up was 137 ± 117.8 days (range, 18–326 days). Clinical improvement of HE occurred in 5 patients (62.5%) with resolution of HE in 4 patients (50%). Single episodes of recurrent gastrointestinal hemorrhage occurred in 3 patients (37.5%). These were self-limiting in 2 cases and successfully managed in 1 case by correction of coagulopathy and blood transfusion. Two of these patients (25%) died, one each of renal failure and hepatorenal failure. Conclusion: The parallel technique of TIPS reduction is reproducible and has a high technical success rate. A dual unilateral transjugular approach is advantageous when performing this procedure. The parallel technique allows repeat bidirectional TIPS adjustment and may be of significant clinical benefit in the management of refractory HE.

  9. Cranial dural arteriovenous shunts. Part 4. Clinical presentation of the shunts with leptomeningeal venous drainage.

    Science.gov (United States)

    Baltsavias, Gerasimos; Spiessberger, Alex; Hothorn, Torsten; Valavanis, Anton

    2015-04-01

    Cranial dural arteriovenous fistulae have been classified into high- and low-risk lesions mainly based on the pattern of venous drainage. Those with leptomeningeal venous drainage carry a higher risk of an aggressive clinical presentation. Recently, it has been proposed that the clinical presentation should be considered as an additional independent factor determining the clinical course of these lesions. However, dural shunts with leptomeningeal venous drainage include a very wide spectrum of inhomogeneous lesions. In the current study, we correlated the clinical presentation of 107 consecutive patients harboring cranial dural arteriovenous shunts with leptomeningeal venous drainage, with their distinct anatomic and angiographic features categorized into eight groups based on the "DES" (Directness and Exclusivity of leptomeningeal venous drainage and features of venous Strain) concept. We found that among these groups, there are significant angioarchitectural differences, which are reflected by considerable differences in clinical presentation. Leptomeningeal venous drainage of dural sinus shunts that is neither direct nor exclusive and without venous strain manifested only benign symptoms (aggressive presentation 0%). On the other end of the spectrum, the bridging vein shunts with direct and exclusive leptomeningeal venous drainage and venous strain are expected to present aggressive symptoms almost always and most likely with bleeding (aggressive presentation 91.5%). Important aspects of the above correlations are discussed. Therefore, the consideration of leptomeningeal venous drainage alone, for prediction of the clinical presentation of these shunts appears insufficient. Angiographic analysis based on the above concept, offers the possibility to distinguish the higher- from the lower-risk types of leptomeningeal venous drainage. In this context, consideration of the clinical presentation as an additional independent factor for the prediction of their clinical

  10. Transjugular Intrahepatic Portosystemic Shunt Dysfunction: Concordance of Clinical Findings, Doppler Ultrasound Examination, and Shunt Venography.

    Science.gov (United States)

    Owen, Joshua M; Gaba, Ron Charles

    2016-01-01

    The objective of this study was to evaluate the concordance between clinical symptoms, Doppler ultrasound (US), and shunt venography for the detection of stent-graft transjugular intrahepatic portosystemic shunt (TIPS) dysfunction. Forty-one patients (M:F 30:11, median age 55 years) who underwent contemporaneous clinical exam, Doppler US, and TIPS venography between 2003 and 2014 were retrospectively studied. Clinical symptoms (recurrent ascites or variceal bleeding) were dichotomously classified as present/absent, and US and TIPS venograms were categorized in a binary fashion as normal/abnormal. US abnormalities included high/low (>190 or 50 cm/s), absent flow, and return of antegrade intra-hepatic portal flow. Venographic abnormalities included shunt stenosis/occlusion and/or pressure gradient elevation. Clinical and imaging concordance rates were calculated. Fifty-two corresponding US examinations and venograms were assessed. The median time between studies was 3 days. Forty of 52 (77%) patients were symptomatic, 33/52 (64%) US examinations were abnormal, and 20/52 (38%) TIPS venograms were abnormal. Concordance between clinical symptoms and TIPS venography was 48% (25/52), while the agreement between US and shunt venography was 65% (34/52). Clinical symptoms and the US concurred in 60% (31/52) of the patients. The sensitivity of clinical symptoms and US for the detection of venographically abnormal shunts was 80% (16/20) and 85% (17/20), respectively. Both clinical symptoms and the US had low specificity (25%, 8/32 and 50%, 16/32) for venographically abnormal shunts. Clinical findings and the US had low concordance rates with TIPS venography, with acceptable sensitivity but poor specificity. These findings suggest the need for improved noninvasive imaging methods for stent-graft TIPS surveillance.

  11. Transjugular Intrahepatic Portosystemic Shunt Dysfunction: Concordance of Clinical Findings, Doppler Ultrasound Examination, and Shunt Venography

    Directory of Open Access Journals (Sweden)

    Joshua M Owen

    2016-01-01

    Full Text Available Objectives: The objective of this study was to evaluate the concordance between clinical symptoms, Doppler ultrasound (US, and shunt venography for the detection of stent-graft transjugular intrahepatic portosystemic shunt (TIPS dysfunction. Materials and Methods: Forty-one patients (M:F 30:11, median age 55 years who underwent contemporaneous clinical exam, Doppler US, and TIPS venography between 2003 and 2014 were retrospectively studied. Clinical symptoms (recurrent ascites or variceal bleeding were dichotomously classified as present/absent, and US and TIPS venograms were categorized in a binary fashion as normal/abnormal. US abnormalities included high/low (>190 or 50 cm/s, absent flow, and return of antegrade intra-hepatic portal flow. Venographic abnormalities included shunt stenosis/occlusion and/or pressure gradient elevation. Clinical and imaging concordance rates were calculated. Results: Fifty-two corresponding US examinations and venograms were assessed. The median time between studies was 3 days. Forty of 52 (77% patients were symptomatic, 33/52 (64% US examinations were abnormal, and 20/52 (38% TIPS venograms were abnormal. Concordance between clinical symptoms and TIPS venography was 48% (25/52, while the agreement between US and shunt venography was 65% (34/52. Clinical symptoms and the US concurred in 60% (31/52 of the patients. The sensitivity of clinical symptoms and US for the detection of venographically abnormal shunts was 80% (16/20 and 85% (17/20, respectively. Both clinical symptoms and the US had low specificity (25%, 8/32 and 50%, 16/32 for venographically abnormal shunts. Conclusion: Clinical findings and the US had low concordance rates with TIPS venography, with acceptable sensitivity but poor specificity. These findings suggest the need for improved noninvasive imaging methods for stent-graft TIPS surveillance.

  12. A bidirectional Optimality Theoretic analysis of multiple negative ...

    African Journals Online (AJOL)

    IT

    6 All examples in this paper are colloquial Afrikaans unless otherwise ...... and bidirectional optimisation over these form-meaning pairs results in the selection of one or ..... Imperfective and perfective habituals in Polish: A bi-directional.

  13. Impedance Changes Indicate Proximal Ventriculoperitoneal Shunt Obstruction In Vitro.

    Science.gov (United States)

    Basati, Sukhraaj; Tangen, Kevin; Hsu, Ying; Lin, Hanna; Frim, David; Linninger, Andreas

    2015-12-01

    Extracranial cerebrospinal fluid (CSF) shunt obstruction is one of the most important problems in hydrocephalus patient management. Despite ongoing research into better shunt design, robust and reliable detection of shunt malfunction remains elusive. The authors present a novel method of correlating degree of tissue ingrowth into ventricular CSF drainage catheters with internal electrical impedance. The impedance based sensor is able to continuously monitor shunt patency using intraluminal electrodes. Prototype obstruction sensors were fabricated for in-vitro analysis of cellular ingrowth into a shunt under static and dynamic flow conditions. Primary astrocyte cell lines and C6 glioma cells were allowed to proliferate up to 7 days within a shunt catheter and the impedance waveform was observed. During cell ingrowth a significant change in the peak-to-peak voltage signal as well as the root-mean-square voltage level was observed, allowing the impedance sensor to potentially anticipate shunt malfunction long before it affects fluid drainage. Finite element modeling was employed to demonstrate that the electrical signal used to monitor tissue ingrowth is contained inside the catheter lumen and does not endanger tissue surrounding the shunt. These results may herald the development of "next generation" shunt technology that allows prediction of malfunction before it affects patient outcome.

  14. Treatment of refractory chylothorax with externalized pleuroperitoneal shunts in children.

    Science.gov (United States)

    Wolff, A B; Silen, M L; Kokoska, E R; Rodgers, B M

    1999-09-01

    Traditional therapy for refractory chylothorax in the pediatric population has included pleurodesis and thoracic duct ligation. These procedures are associated with high morbidity and questionable success rates. We retrospectively reviewed our experience with 15 patients who underwent treatment for chylous effusions using pleuroperitoneal shunts with exteriorized pump chambers. Mean patient age at time of shunt placement was 2.1 (0.1 to 11.5) years and the most common indication (7 of 15) was refractory chylothorax following surgical correction of congenital heart disease. Mean chylothorax duration before shunt placement was 76 (5 to 810) days and shunts were in place for an average of 104 (12 to 365) days. A total of 19 chylous effusions (pleural or pericardial) were treated with shunts. Nine of 11 right-sided chylothoraces, 5 of 6 left-sided chylothoraces, and 2 of 2 chylopericardia resolved with shunt therapy (84% total). Pleuroperitoneal shunting failed to clear the effusion in 3 children. There were six episodes of shunt malfunction that were repaired and two episodes of infection. Inguinal or umbilical hernia developed in 4 patients. Externalized pleuroperitoneal shunting is a safe, effective, and minimally invasive treatment for children with refractory chylous effusions.

  15. Superconducting fault current-limiter with variable shunt impedance

    Science.gov (United States)

    Llambes, Juan Carlos H; Xiong, Xuming

    2013-11-19

    A superconducting fault current-limiter is provided, including a superconducting element configured to resistively or inductively limit a fault current, and one or more variable-impedance shunts electrically coupled in parallel with the superconducting element. The variable-impedance shunt(s) is configured to present a first impedance during a superconducting state of the superconducting element and a second impedance during a normal resistive state of the superconducting element. The superconducting element transitions from the superconducting state to the normal resistive state responsive to the fault current, and responsive thereto, the variable-impedance shunt(s) transitions from the first to the second impedance. The second impedance of the variable-impedance shunt(s) is a lower impedance than the first impedance, which facilitates current flow through the variable-impedance shunt(s) during a recovery transition of the superconducting element from the normal resistive state to the superconducting state, and thus, facilitates recovery of the superconducting element under load.

  16. Over-drainage and persistent shunt-dependency in patients with idiopathic intracranial hypertension treated with shunts and bariatric surgery.

    Science.gov (United States)

    Roth, Jonathan; Constantini, Shlomi; Kesler, Anat

    2015-01-01

    Idiopathic intracranial hypertension (IIH) may lead to visual impairment. Shunt surgery is indicated for refractory IIH-related symptoms that persist despite medical treatment, or those presenting with significant visual decline. Obesity is a risk factor for IIH; a reduction in weight has been shown to improve papilledema. Bariatric surgery (BS) has been suggested for treating IIH associated with morbid obesity. In this study, we describe a high rate of over-drainage (OD) seen in patients following shunts and BS. The study cohort includes 13 patients with IIH that underwent shunt surgery for treatment of the IIH-related symptoms. Six patients underwent BS in addition to the shunt surgery (but not concomitantly). Seven patients had only shunt surgeries with no BS. Data were collected retrospectively. BS effectively led to weight reduction (body mass index decreasing from 43 ± 4 to 28 ± 5). Patients undergoing BS had 1-6 (2.5 ± 1.9) shunt revisions for OD following BS, as opposed to 0-3 (1.4 ± 1.1) revisions prior to BS over similar time spans (statistically insignificant difference), and 0-6 (1.6 ± 2.5) revisions among the non-BS patients over a longer time span (statistically insignificant difference). Two patients in the BS group underwent shunt externalization and closure; however, they proved to be shunt-dependent. Patients with IIH that undergo shunt surgery and BS (not concomitantly) may suffer from OD symptoms, necessitating multiple shunt revisions, and valve upgrades. Despite BS being a valid primary treatment for some patients with IIH, among shunted patients, BS may not lead to resolution of IIH-related symptoms and patients may remain shunt-dependent.

  17. Bidirectional communication using delay coupled chaotic directly ...

    Indian Academy of Sciences (India)

    A symmetric bidirectional coupling is identified as a suitable method for isochronal synchronization of such lasers. The optimum values of coupling and feedback strength that can provide maximum quality of synchronization are identified. This method is successfully employed for encoding/decoding both analog and digital ...

  18. Bidirectional ventricular tachycardia of unusual etiology

    Directory of Open Access Journals (Sweden)

    Praloy Chakraborty

    2015-11-01

    Full Text Available Bidirectional ventricular tachycardia (BDVT is a rare form of ventricular arrhythmia, characterized by changing QRS axis of 180 degrees. Digitalis toxicity is considered as commonest cause of BDVT; other causes include aconite toxicity, myocarditis, myocardial infarction, metastatic cardiac tumour and cardiac channelopathies. We describe a case of BDVT in a patient with Anderson-Tawil syndrome.

  19. Intergenerational Transmission in a Bidirectional Context

    Directory of Open Access Journals (Sweden)

    Jan De Mol

    2013-07-01

    Full Text Available Traditional approaches to the study of parent-child relationships view intergenerational transmission as a top-down phenomenon in which parents transfer their values, beliefs, and practices to their children. Furthermore, the focus of these unidirectional approaches regarding children's internalisation processes is on continuity or the transmission of similar values, beliefs, and practices from parents to children. Analogous unidirectional perspectives have also influenced the domain of family therapy. In this paper a cognitive-bidirectional and dialectical model of dynamics in parent-child relationships is discussed in which the focus is on continual creation of novel meanings and not just reproduction of old ones in the bidirectional transmission processes between parents and children. Parents and children are addressed as full and equally agents in their interdependent relationship, while these relational dynamics are embedded within culture. This cultural context complicates bidirectional transmission influences in the parent-child relationship as both parents and children are influenced by many other contexts. Further, current research in the domain of parent-child relationships and current concepts of intergenerational transmission in family therapy are reviewed from a bidirectional cognitive-dialectical perspective.

  20. Uncertainties in the Bidirectional Biodiesel Supply Chain

    NARCIS (Netherlands)

    Bot, Pieter; van Donk, Dirk Pieter; Pennink, Bartjan; Simatupang, Togar M.

    2015-01-01

    For remote areas, small-scale local biodiesel production is particularly attractive if producers and consumers are the same. Such supply chains are labeled as bidirectional. However, little is known on how raw material supply, transportation, logistics, production and operations uncertainties impact

  1. Network Coding in the Bidirectional Cross

    DEFF Research Database (Denmark)

    Ertli, Gergö; Paramanathan, Achuthan; Rein, Stephan Alexander

    2013-01-01

    This paper presents a detailed performance evaluation of inter-session network coding in wireless meshed networks in terms of throughput and energy consumption. A full analytical model is given for three different communication approaches for the bidirectional cross topology using an IEEE 802.11 ...

  2. Rate of shunt revision as a function of age in patients with shunted hydrocephalus due to myelomeningocele.

    Science.gov (United States)

    Dupepe, Esther B; Hopson, Betsy; Johnston, James M; Rozzelle, Curtis J; Jerry Oakes, W; Blount, Jeffrey P; Rocque, Brandon G

    2016-11-01

    OBJECTIVE It is generally accepted that cerebrospinal fluid shunts fail most frequently in the first years of life. The purpose of this study was to describe the risk of shunt failure for a given patient age in a well-defined cohort with shunted hydrocephalus due to myelomeningocele (MMC). METHODS The authors analyzed data from their institutional spina bifida research database including all patients with MMC and shunted hydrocephalus. For the entire population, the number of shunt revisions in each year of life was determined. Then the number of patients at risk for shunt revision during each year of life was calculated, thus enabling them to calculate the rate of shunt revision per patient in each year of life. In this way, the timing of all shunt revision operations for the entire clinic population and the likelihood of having a shunt revision during each year of life were calculated. RESULTS A total of 655 patients were enrolled in the spina bifida research database, 519 of whom had a diagnosis of MMC and whose mean age was 17.48 ± 11.7 years (median 16 years, range 0-63 years). Four hundred seventeen patients had had a CSF shunt for the treatment of hydrocephalus and thus are included in this analysis. There were 94 shunt revisions in the 1st year of life, which represents a rate of 0.23 revisions per patient in that year. The rate of shunt revision per patient-year initially decreased as age increased, except for an increase in revision frequency in the early teen years. Shunt revisions continued to occur as late as 43 years of age. CONCLUSIONS These data substantiate the idea that shunt revision surgeries in patients with MMC are most common in the 1st year of life and decrease thereafter, except for an increase in the early teen years. A persistent risk of shunt failure was observed well into adult life. These findings underscore the importance of routine follow-up of all MMC patients with shunted hydrocephalus and will aid in counseling patients and

  3. Subgaleo-peritoneal shunt: An effective and safer alternative to lumboperitoneal shunt in the management of persistent or recurrent iatrogenic cranial pseudomeningoceles.

    Science.gov (United States)

    Kiran, Narayanam Anantha Sai; Thakar, Sumit; Mohan, Dilip; Aryan, Saritha; Rao, Arun Sadashiva; Hegde, Alangar S

    2013-01-01

    Subgaleo-peritoneal (SP) shunting for pseudomeningoceles (PMCs) is an effective and safer alternative as compared to the lumboperitoneal (LP) shunt. SP shunting was done in six patients (14-60 years) with persistent or recurrent PMCs using the cranial (ventricular part) and the distal parts of a Chhabra shunt connected by a rigid connector without any intervening chamber or valve. Two patients had undergone a prior LP shunt that had failed. One patient was unsuitable for a LP shunt placement. The PMC subsided completely in all the patients following the SP shunt. In one patient, the shunt got displaced and required repositioning. None of the patients developed symptoms of over-drainage or any other complication. All patients were asymptomatic at a mean follow-up of 15 months. These results suggest that SP shunting is a safe, simple, and effective alternative to the traditional LP shunt in the management of persistent or recurrent cranial PMCs.

  4. Internal carotid artery rupture caused by carotid shunt insertion.

    Science.gov (United States)

    Illuminati, Giulio; Caliò, Francesco G; Pizzardi, Giulia; Vietri, Francesco

    2015-01-01

    Shunting is a well-accepted method of maintaining cerebral perfusion during carotid endarterectomy (CEA). Nonetheless, shunt insertion may lead to complications including arterial dissection, embolization, and thrombosis. We present a complication of shunt insertion consisting of arterial wall rupture, not reported previously. A 78-year-old woman underwent CEA combined with coronary artery bypass grafting (CABG). At the time of shunt insertion an arterial rupture at the distal tip of the shunt was detected and was repaired via a small saphenous vein patch. Eversion CEA and subsequent CABG completed the procedure whose postoperative course was uneventful. Shunting during combined CEA-CABG may be advisable to assure cerebral protection from possible hypoperfusion due to potential hemodynamic instability of patients with severe coronary artery disease. Awareness and prompt management of possible shunt-related complications, including the newly reported one, may contribute to limiting their harmful effect. Arterial wall rupture is a possible, previously not reported, shunt-related complication to be aware of when performing CEA. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  5. Evaluation of Blalock-Taussig shunts using magnetic resonance imaging

    International Nuclear Information System (INIS)

    Okajima, Yoshitomo; Tashima, Kazuyuki; Terai, Masaru; Niwa, Koichirou.

    1988-01-01

    Four patients aged 3 to 18 months (mean 13 months) with a total of five Blalock-Taussig shunts (BT shunts; two were original BT shunts and three were modified BT shunts using GOLASKI grafts) underwent evaluation by ECG-gated magnetic resonance imaging. There were two cases with pulmonary atresia with intact ventricular septum, one with double outlet right ventricle with pulmonary stenosis and one with tetralogy of Fallot with pulmonary atresia who underwent bilateral BT shunts. At the time of study, an auscultory shunt murmur was audible in all patients. The magnetic resonance images were obtained with a Picker International Vista MR with a superconducting magnet operating at 0.5 Tesla. A spin echo sequence (echo time 40 msec) was used. All patients were placed within a 30 cm head coil radio antenna and sedated with chloral hydrate or diazepam. Four of 5 shunts were imaged on both coronal sections and sagittal sections during enddiastole. And there was no signal within the grafts. When the velocity of blood flow is beyond the cutoff velocity, the signal intensity of flowing blood is near background level. So we judged these grafts were patient. Our results showed that MRI was a very useful noninvasive method for evaluation of BT shunts. (author)

  6. Evaluation of Blalock-Taussig shunts using magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Okajima, Yoshitomo; Tashima, Kazuyuki; Terai, Masaru; Niwa, Koichirou.

    1988-10-01

    Four patients aged 3 to 18 months (mean 13 months) with a total of five Blalock-Taussig shunts (BT shunts; two were original BT shunts and three were modified BT shunts using GOLASKI grafts) underwent evaluation by ECG-gated magnetic resonance imaging. There were two cases with pulmonary atresia with intact ventricular septum, one with double outlet right ventricle with pulmonary stenosis and one with tetralogy of Fallot with pulmonary atresia who underwent bilateral BT shunts. At the time of study, an auscultory shunt murmur was audible in all patients. The magnetic resonance images were obtained with a Picker International Vista MR with a superconducting magnet operating at 0.5 Tesla. A spin echo sequence (echo time 40 msec) was used. All patients were placed within a 30 cm head coil radio antenna and sedated with chloral hydrate or diazepam. Four of 5 shunts were imaged on both coronal sections and sagittal sections during enddiastole. And there was no signal within the grafts. When the velocity of blood flow is beyond the cutoff velocity, the signal intensity of flowing blood is near background level. So we judged these grafts were patient. Our results showed that MRI was a very useful noninvasive method for evaluation of BT shunts.

  7. Splenophrenic portosystemic shunt in dogs with and without portal ...

    African Journals Online (AJOL)

    The possible existence of the same pattern of porto-caval connection in dogs having a single congenital portosystemic shunt (CPSS) and in dogs having multiple acquired portosystemic shunt (MAPSS) secondary to portal hypertension (PH) was evaluated. Retrospective evaluation of all CT examinations of patients having ...

  8. Spontaneous knot; a rare cause of ventriculoperitoneal shunt blockage.

    LENUS (Irish Health Repository)

    Mohammed, Wail

    2011-02-01

    A 14-year old X linked congenital hydrocephalus presented with unexplained headaches and vomiting. He had external ventricular drain and intracranial pressure monitoring (ICP). Subsequently, he underwent exploration and removal of previously inserted ventriculoperitoneal (VP) shunts. On retrieval of peritoneal catheters a double knot was noted between his two distal catheters. This case illustrates a rare cause of ventriculoperitoneal shunt malfunction.

  9. Spontaneous knot; a rare cause of ventriculoperitoneal shunt blockage.

    LENUS (Irish Health Repository)

    Mohammed, Wail

    2012-02-01

    A 14-year old X linked congenital hydrocephalus presented with unexplained headaches and vomiting. He had external ventricular drain and intracranial pressure monitoring (ICP). Subsequently, he underwent exploration and removal of previously inserted ventriculoperitoneal (VP) shunts. On retrieval of peritoneal catheters a double knot was noted between his two distal catheters. This case illustrates a rare cause of ventriculoperitoneal shunt malfunction.

  10. Clopidogrel in infants with systemic-to-pulmonary-artery shunts

    DEFF Research Database (Denmark)

    Wessel, David L; Berger, Felix; Li, Jennifer S

    2013-01-01

    BACKGROUND: Infants with cyanotic congenital heart disease palliated with placement of a systemic-to-pulmonary-artery shunt are at risk for shunt thrombosis and death. We investigated whether the addition of clopidogrel to conventional therapy reduces mortality from any cause and morbidity relate......-related morbidity. (Funded by Sanofi-Aventis and Bristol-Myers Squibb; ClinicalTrials.gov number, NCT00396877.)....

  11. Migration of the peritoneal catheter of a ventriculoperitoneal shunt ...

    African Journals Online (AJOL)

    Ventricular shunt is a well-established modality in the management of hydrocephalus. However, it can be associated with numerous complications and disastrous consequences. The reported incidence of intra-abdominal complications in infants and children after ventriculoperitoneal (VP) shunt procedures is about 24% ...

  12. Shunt hybrid active power filter for harmonic mitigation: A practical ...

    Indian Academy of Sciences (India)

    The increasing importance of Power Quality problems has been responsible for several improvements in Active Power Filter (APF) typologies in the last decade. The increased cost and switching losses make a pure shunt APF economically impractical for high power applications. In higher power levels shunt Hybrid Active ...

  13. Leakage Inductance Calculation for Planar Transformers with a Magnetic Shunt

    DEFF Research Database (Denmark)

    Zhang, Jun; Ouyang, Ziwei; Duffy, Maeve C.

    2014-01-01

    with a magnetic shunt by means of the stored magnetic energy in the primary and secondary sides of the transformer using the magnetomotive force (MMF) variation method, as well as the stored energy in the shunt based on the reluctance model. The detailed calculation method is described. Both the FEA simulation...

  14. An unusual case of intrahepatic portosystemic venous shunt

    African Journals Online (AJOL)

    vena cava (IVC) (most common). Intrahepatic portosystemic venous shunts are rare vascular anomalies that may be detected in asymptomatic patients, given the recent advances in radiological imaging techniques. Accurate shunt evaluation and classification can be performed with ultrasound and multi-detector computed.

  15. Calibration of piezoelectric RL shunts with explicit residual mode correction

    DEFF Research Database (Denmark)

    Høgsberg, Jan Becker; Krenk, Steen

    2017-01-01

    Piezoelectric RL (resistive-inductive) shunts are passive resonant devices used for damping of dominant vibration modes of a flexible structure and their efficiency relies on the precise calibration of the shunt components. In the present paper improved calibration accuracy is attained by an exte......Piezoelectric RL (resistive-inductive) shunts are passive resonant devices used for damping of dominant vibration modes of a flexible structure and their efficiency relies on the precise calibration of the shunt components. In the present paper improved calibration accuracy is attained...... by an extension of the local piezoelectric transducer displacement by two additional terms, representing the flexibility and inertia contributions from the residual vibration modes not directly addressed by the shunt damping. This results in an augmented dynamic model for the targeted resonant vibration mode...

  16. Shunt attachment and method for interfacing current collection systems

    Science.gov (United States)

    Denney, Paul E.; Iyer, Natraj C.; Hannan, III, William F.

    1992-01-01

    A composite brush to shunt attachment wherein a volatile component of a composite but mostly metallic brush, used for current collection purposes, does not upon welding or brazing, adversely affect the formation of the interfacial bond with a conductive shunt which carries the current from the zone of the brush. The brush to shunt attachment for a brush material of copper-graphite composite and a shunt of copper, or substituting silver for copper as an alternative, is made through a hot isostatic pressing (HIP). The HIP process includes applying high pressure and temperature simultaneously at the brush to shunt interface, after it has been isolated or canned in a metal casing in which the air adjacent to the interface has been evacuated and the interfacial area has been sealed before the application of pressure and temperature.

  17. Vibration damping with negative capacitance shunts: theory and experiment

    International Nuclear Information System (INIS)

    De Marneffe, B; Preumont, A

    2008-01-01

    This paper analyzes in detail the enhancement of piezoelectric stack transducers by means of the well known 'negative' capacitive shunting. The stability is thoroughly studied: starting from the electrical admittance curve of the transducer, a method is introduced that quantifies the stability margins of the shunted structure. Two different implementations (series vs parallel) are investigated, and the lack of robustness of the parallel one is demonstrated. Next, this technique is experimentally applied on a truss structure. Its performances are compared with those of passive shunt circuits and with those of an active control law, the so-called Integral Force Feedback or IFF. As expected, the damping introduced by the negative capacitance shunt is larger than the damping obtained with the passive shunts; it remains, however, one order of magnitude smaller than that obtained with the IFF

  18. Percutaneous peritoneovenous shunt positioning: technique and preliminary results

    International Nuclear Information System (INIS)

    Orsi, Franco; Grasso, Rosario Francesco; Bonomo, Guido; Marinucci, Irene; Monti, Cinzia; Bellomi, Massimo

    2002-01-01

    Nine peritoneovenous shunts were positioned by percutaneous technique in seven patients with advanced malignancy causing severe refractory ascites, and in two patients with hepatic cirrhosis (one with hepatocarcinoma). In all patients the shunts were percutaneously placed through the subclavian vein in the angiographic suite under digital fluoroscopic guide. No complications directly related to the procedure occurred. The shunt was successfully positioned in all patients in 60 min average time. No patient showed symptoms related to pulmonary overload or to disseminated intravascular coagulation. All patients had a significant improvement of the objective symptoms related to ascites such as respiratory symptoms, dyspepsia, and functional impairment to evacuation describing an improvement of their quality of life. Maximum shunt patency was 273 days. Percutaneous placement of peritoneovenous shunt is a safe, fast, and inexpensive procedure, extremely useful in resolution of refractory ascites, reducing symptoms, and allowing effective palliation, with a great improvement in quality of life. (orig.)

  19. Percutaneous peritoneovenous shunt positioning: technique and preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Orsi, Franco; Grasso, Rosario Francesco; Bonomo, Guido; Marinucci, Irene [Division of Radiology, European Institute of Oncology, Milan (Italy); Monti, Cinzia [Institute of Radiology, University of Milan (Italy); Bellomi, Massimo [Division of Radiology, European Institute of Oncology, Milan (Italy); Institute of Radiology, University of Milan (Italy)

    2002-05-01

    Nine peritoneovenous shunts were positioned by percutaneous technique in seven patients with advanced malignancy causing severe refractory ascites, and in two patients with hepatic cirrhosis (one with hepatocarcinoma). In all patients the shunts were percutaneously placed through the subclavian vein in the angiographic suite under digital fluoroscopic guide. No complications directly related to the procedure occurred. The shunt was successfully positioned in all patients in 60 min average time. No patient showed symptoms related to pulmonary overload or to disseminated intravascular coagulation. All patients had a significant improvement of the objective symptoms related to ascites such as respiratory symptoms, dyspepsia, and functional impairment to evacuation describing an improvement of their quality of life. Maximum shunt patency was 273 days. Percutaneous placement of peritoneovenous shunt is a safe, fast, and inexpensive procedure, extremely useful in resolution of refractory ascites, reducing symptoms, and allowing effective palliation, with a great improvement in quality of life. (orig.)

  20. Parylene MEMS patency sensor for assessment of hydrocephalus shunt obstruction.

    Science.gov (United States)

    Kim, Brian J; Jin, Willa; Baldwin, Alexander; Yu, Lawrence; Christian, Eisha; Krieger, Mark D; McComb, J Gordon; Meng, Ellis

    2016-10-01

    Neurosurgical ventricular shunts inserted to treat hydrocephalus experience a cumulative failure rate of 80 % over 12 years; obstruction is responsible for most failures with a majority occurring at the proximal catheter. Current diagnosis of shunt malfunction is imprecise and involves neuroimaging studies and shunt tapping, an invasive measurement of intracranial pressure and shunt patency. These patients often present emergently and a delay in care has dire consequences. A microelectromechanical systems (MEMS) patency sensor was developed to enable direct and quantitative tracking of shunt patency in order to detect proximal shunt occlusion prior to the development of clinical symptoms thereby avoiding delays in treatment. The sensor was fabricated on a flexible polymer substrate to eventually allow integration into a shunt. In this study, the sensor was packaged for use with external ventricular drainage systems for clinical validation. Insights into the transduction mechanism of the sensor were obtained. The impact of electrode size, clinically relevant temperatures and flows, and hydrogen peroxide (H2O2) plasma sterilization on sensor function were evaluated. Sensor performance in the presence of static and dynamic obstruction was demonstrated using 3 different models of obstruction. Electrode size was found to have a minimal effect on sensor performance and increased temperature and flow resulted in a slight decrease in the baseline impedance due to an increase in ionic mobility. However, sensor response did not vary within clinically relevant temperature and flow ranges. H2O2 plasma sterilization also had no effect on sensor performance. This low power and simple format sensor was developed with the intention of future integration into shunts for wireless monitoring of shunt state and more importantly, a more accurate and timely diagnosis of shunt failure.

  1. Tube shunt complications and their prevention.

    Science.gov (United States)

    Sarkisian, Steven R

    2009-03-01

    Glaucoma drainage devices (GDDs) have been generally accepted as a treatment of refractory glaucoma. GDDs have their own unique set of complications that are important to evaluate to prevent them. Tube shunts are typically used in eyes with refractory glaucoma. There is increased interest in studying the efficacy of GDDs. Most of the attention has been focused on comparing trabeculectomy with the Baerveldt implant (Advanced Medical Optics, Inc., Santa Anna, California, USA). The other leading implant is the Ahmed Glaucoma Valve. There are several retrospective studies comparing these two devices and a prospective study is ongoing. There is great interest in the complication rate of tube shunts and these have been published both retrospectively and prospectively. Complications such as hypotony, diplopia, strabismus, proptosis, tube erosion, failure, corneal decompensation, endophthalmitis, and visual loss are all important and some have recently been reviewed in the literature. Moreover, the use of glaucoma drainage implants in the pediatric population has been evaluated. Glaucoma drainage implants have been a powerful tool in our surgical fight to prevent blindness; however, they are not without complications or controversy.

  2. Bidirectional dc-to-dc Power Converter

    Science.gov (United States)

    Griesbach, C. R.

    1986-01-01

    Solid-state, series-resonant converter uses high-voltage thyristors. Converter used either to convert high-voltage, low-current dc power to lowvoltage, high current power or reverse. Taking advantage of newly-available high-voltage thyristors to provide better reliability and efficiency than traditional converters that use vacuum tubes as power switches. New converter essentially maintenance free and provides greatly increased mean time between failures. Attractive in industrial applications whether or not bidirectional capability is required.

  3. Bidirectional optimization of the melting spinning process.

    Science.gov (United States)

    Liang, Xiao; Ding, Yongsheng; Wang, Zidong; Hao, Kuangrong; Hone, Kate; Wang, Huaping

    2014-02-01

    A bidirectional optimizing approach for the melting spinning process based on an immune-enhanced neural network is proposed. The proposed bidirectional model can not only reveal the internal nonlinear relationship between the process configuration and the quality indices of the fibers as final product, but also provide a tool for engineers to develop new fiber products with expected quality specifications. A neural network is taken as the basis for the bidirectional model, and an immune component is introduced to enlarge the searching scope of the solution field so that the neural network has a larger possibility to find the appropriate and reasonable solution, and the error of prediction can therefore be eliminated. The proposed intelligent model can also help to determine what kind of process configuration should be made in order to produce satisfactory fiber products. To make the proposed model practical to the manufacturing, a software platform is developed. Simulation results show that the proposed model can eliminate the approximation error raised by the neural network-based optimizing model, which is due to the extension of focusing scope by the artificial immune mechanism. Meanwhile, the proposed model with the corresponding software can conduct optimization in two directions, namely, the process optimization and category development, and the corresponding results outperform those with an ordinary neural network-based intelligent model. It is also proved that the proposed model has the potential to act as a valuable tool from which the engineers and decision makers of the spinning process could benefit.

  4. Ventriculoperitoneal shunt infection in Haji Adam Malik Hospital, Medan

    Science.gov (United States)

    Dharmajaya, R.

    2018-03-01

    Installation of ventriculoperitoneal shunts (VP) represented a substantial progress in the neurosurgical management of hydrocephalus in children. However, infection is the most commonpostoperative complication of aventriculoperitoneal shunt. It is important because it is related to substantial morbidity and mortality, and exerts a negative impact on the quality of life of patients. We retrospectively analyzed all 20 cases of shunt infection from 2013 to 2016. The types of infections found were exposed shunts15 cases (75%), and 5 cases of ventriculitis (25%). Length of infection time which calculated from the beginning of surgery was 350.20 days or 11 months. The most common pathogen types are S. epidermidis followed by P. aeruginosa, E. coli, and A. baumanii. There were many risk factors for shunt infection, but the interesting fact was the level of pre-operative albumin. There was a significant difference between low albumin levels (<3.0) and normal albumin (≥3.0) levels against the risk of exposure shunt, p = 0.015. It means there is asignificant difference between low pre-operative albumin and normal level for the risk of theexposed shunt.

  5. A plasma polymerization technique to overcome cerebrospinal fluid shunt infections

    Energy Technology Data Exchange (ETDEWEB)

    Coekeliler, D [Plasma Aided Bioengineering and Biotechnology Research Laboratory, Engineering Faculty, Hacettepe University, 06532, Ankara (Turkey); Caner, H [Department of Neurosurgery, School of Medicine, Baskent University, 06610, Ankara (Turkey); Zemek, J [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53, Prague, Czech Republic (Czech Republic); Choukourov, A [Department of Macromolecular Physics, Charles University, V Holesovickach 2, 18000 Prague (Czech Republic); Biederman, H [Department of Macromolecular Physics, Charles University, V Holesovickach 2, 18000 Prague (Czech Republic); Mutlu, M [Plasma Aided Bioengineering and Biotechnology Research Laboratory, Engineering Faculty, Hacettepe University, 06532, Ankara (Turkey)

    2007-03-01

    Prosthetic devices, mainly shunts, are frequently used for temporary or permanent drainage of cerebrospinal fluid. The pathogenesis of shunt infection is a very important problem in modern medicine and generally this is characterized by staphylococcal adhesion to the cerebrospinal fluid shunt surfaces. In this paper, the prevention of the attachment of test microorganism Staphylococcus epidermidis on the cerebrospinal fluid shunt surfaces by 2-hydroxyethylmethacrylate (HEMA) precursor modification in the plasma polymerization system, is reported. Different plasma polymerization conditions (RF discharge power 10-20-30 W, exposure time 5-10-15 min) were employed during the surface modification. The surface chemistry and topology of unmodified and modified shunts was characterized by x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Also, static contact angle measurements were performed to state the change of surface hydrophilicity. All samples were tested in vitro with Staphylococcus epidermidis. A plasma-polymerized HEMA film (PP HEMA) was found to be an alternative simple method to decrease the microorganism attachment and create bacterial anti-fouling surfaces. The attachment of the model microorganism Staphylococcus epidermidis on the shunt surface modified by PP HEMA at 20 W and 15 min was reduced 62.3% if compared to the unmodified control surface of the shunt.

  6. Research on spark discharge of floating roof tank shunt

    International Nuclear Information System (INIS)

    Bi, Xiaolei; Liu, Quanzhen; Liu, Baoquan; Gao, Xin; Hu, Haiyan; Liu, Juan

    2013-01-01

    In order to quantitatively analyze the spark discharge risk of floating roof tank shunts, the breakdown voltage of shunt has been calculated by Townsend theory, the shunt spark discharge experiment is carried out by using 1.2/50 μs impulse voltage wave, and the relationship between breakdown voltage of shunt spark discharge and air gap is analyzed. It has been indicated by theoretical analysis and experimental study that the small gap is more easily cause spark discharge than the big gap when the contact between shunt and tank shell is poor. When air gap distance is equal to 0.1 cm, average breakdown voltage is 5280 V. When the air gap distance is less than 0.3 cm, experiment data agree well with Townsend theory. Therefore, in the condition of small gap, Townsend theory can be used to calculated breakdown voltage of shunt. Finally, based on the above conclusions, improvements for avoiding the spark discharge risk of shunt of floating roof tanks have been proposed.

  7. Aberrant hepatic lipid storage and metabolism in canine portosystemic shunts.

    Directory of Open Access Journals (Sweden)

    Lindsay Van den Bossche

    Full Text Available Non-alcoholic fatty liver disease (NAFLD is a poorly understood multifactorial pandemic disorder. One of the hallmarks of NAFLD, hepatic steatosis, is a common feature in canine congenital portosystemic shunts. The aim of this study was to gain detailed insight into the pathogenesis of steatosis in this large animal model. Hepatic lipid accumulation, gene-expression analysis and HPLC-MS of neutral lipids and phospholipids in extrahepatic (EHPSS and intrahepatic portosystemic shunts (IHPSS was compared to healthy control dogs. Liver organoids of diseased dogs and healthy control dogs were incubated with palmitic- and oleic-acid, and lipid accumulation was quantified using LD540. In histological slides of shunt livers, a 12-fold increase of lipid content was detected compared to the control dogs (EHPSS P<0.01; IHPSS P = 0.042. Involvement of lipid-related genes to steatosis in portosystemic shunting was corroborated using gene-expression profiling. Lipid analysis demonstrated different triglyceride composition and a shift towards short chain and omega-3 fatty acids in shunt versus healthy dogs, with no difference in lipid species composition between shunt types. All organoids showed a similar increase in triacylglycerols after free fatty acids enrichment. This study demonstrates that steatosis is probably secondary to canine portosystemic shunts. Unravelling the pathogenesis of this hepatic steatosis might contribute to a better understanding of steatosis in NAFLD.

  8. Aberrant hepatic lipid storage and metabolism in canine portosystemic shunts.

    Science.gov (United States)

    Van den Bossche, Lindsay; Schoonenberg, Vivien A C; Burgener, Iwan A; Penning, Louis C; Schrall, Ingrid M; Kruitwagen, Hedwig S; van Wolferen, Monique E; Grinwis, Guy C M; Kummeling, Anne; Rothuizen, Jan; van Velzen, Jeroen F; Stathonikos, Nikolas; Molenaar, Martijn R; Helms, Bernd J; Brouwers, Jos F H M; Spee, Bart; van Steenbeek, Frank G

    2017-01-01

    Non-alcoholic fatty liver disease (NAFLD) is a poorly understood multifactorial pandemic disorder. One of the hallmarks of NAFLD, hepatic steatosis, is a common feature in canine congenital portosystemic shunts. The aim of this study was to gain detailed insight into the pathogenesis of steatosis in this large animal model. Hepatic lipid accumulation, gene-expression analysis and HPLC-MS of neutral lipids and phospholipids in extrahepatic (EHPSS) and intrahepatic portosystemic shunts (IHPSS) was compared to healthy control dogs. Liver organoids of diseased dogs and healthy control dogs were incubated with palmitic- and oleic-acid, and lipid accumulation was quantified using LD540. In histological slides of shunt livers, a 12-fold increase of lipid content was detected compared to the control dogs (EHPSS Plipid-related genes to steatosis in portosystemic shunting was corroborated using gene-expression profiling. Lipid analysis demonstrated different triglyceride composition and a shift towards short chain and omega-3 fatty acids in shunt versus healthy dogs, with no difference in lipid species composition between shunt types. All organoids showed a similar increase in triacylglycerols after free fatty acids enrichment. This study demonstrates that steatosis is probably secondary to canine portosystemic shunts. Unravelling the pathogenesis of this hepatic steatosis might contribute to a better understanding of steatosis in NAFLD.

  9. Portosystemic shunts for extrahepatic portal hypertension in children.

    Science.gov (United States)

    Tocornal, J; Cruz, F

    1981-07-01

    Twenty-three children with prehepatic portal hypertension and hemorrhage due to ruptured esophagogastric varices had portosystemic shunts. Their ages ranged from two years and seven months to 15 years. Eleven were less than eight years of age. Twenty patients had portal vein cavernomatosis and three patients had double portal veins. In 21 patients, a mesocaval type of shunt was done. A splenorenal shunt was performed in two. There was no surgical mortality. Two shunts occluded, both in rather young infants--two years and seven months and three years of age. In all the others, there was no further bleeding, and the shunts remained patent, as shown by abdominal angiograms. Neuropsychiatric disorders, probably due to hepatic encephalopathy, occurred in only one patient. On the basis of this favorable experience, we believe that an elective portosystemic shunt should, in general, be performed upon children with prehepatic portal hypertension after one major variceal hemorrhage. We favor a mesocaval type of shunt in these children because of the larger diameter of the vessels involved in the anastomosis and because it preserves the spleen, maintaining defense against subsequent infection.

  10. Muzzle shunt augmentation of conventional railguns

    International Nuclear Information System (INIS)

    Parker, J.V.

    1991-01-01

    This paper reports on augmentation which is a technique for reducing the armature current and hence the armature power dissipation in a plasma armature railgun. In spite of the advantages, no large augmented railguns have been built, primarily due to the mechanical and electrical complexity introduced by the extra conductors required. it is possible to achieve some of the benefits of augmentation in a conventional railgun by diverting a fraction φ of the input current through a shunt path at the muzzle of the railgun. In particular, the relation between force and armature current is the same as that obtained in an n-turn, series-connected augmented railgun with n = 1/(1 - φ). The price of this simplification is a reduction in electrical efficiency and some additional complexity in the external electrical system

  11. Prevention and treatment of complications after transjugular intrahepatic portosystemic shunt

    Directory of Open Access Journals (Sweden)

    XUE Hui

    2016-02-01

    Full Text Available The application of transjugular intrahepatic portosystemic shunt (TIPS in the treatment of cirrhotic portal hypertension has been widely accepted both at home and abroad. This article focuses on the fatal complications of TIPS (including intraperitoneal bleeding and acute pulmonary embolism, shunt failure, and recurrent portosystemic hepatic encephalopathy, and elaborates on the reasons for such conditions and related preventive measures, in order to improve the accuracy and safety of intraoperative puncture, reduce common complications such as shunt failure and hepatic encephalopathy, and improve the clinical effect of TIPS in the treatment of cirrhotic portal hypertension.

  12. Spinal cord arteriovenous shunts: from imaging to management

    International Nuclear Information System (INIS)

    Rodesch, G.; Lasjaunias, P.

    2003-01-01

    Spinal cord arteriovenous shunts (SCAVSs) are either fistulas or niduses that can be separated in four different groups according to their localization and relationship to the dura. Paraspinal AVSs are located outside the spine and are responsible for neurological symptoms because of cord compression by ertatic veins, venous congestion or arterial steal. Epidural shunts are located in the epidural space and drain in epidural veins with secondary intradural congestion. Dural shunts are embedded in the dura, produce a cord venous myelopathy after draining through veins that either pierce the dura far from a nerve root or accompany a nerve root. Intradural shunts affect the cord, the roots or the filum. Additionally, they can be classified according to their potential relationships with genetics, vascular biological features and angiogenesis into genetic hereditary lesions (hereditary hemorrhagic telangiectasia), genetic non-hereditary lesions (multiple lesions with metameric links) and single lesions (AVMs or micro AVFs). MRI and MRA are able to visualise SCAVS early after the onset of clinical symptoms. The type of shunt and its localization may remain difficult to be precise. Angiography remains the gold standard for analysis of the anatomical, morphological and architectural features necessary for therapeutic decisions in both paediatric and adult populations. In our series, embolisation is chosen in first intention whatever the type of shunt responsible for the clinical symptoms and glue is preferably used. In paraspinal, dural or epidural arteriovenous shunts, the goal of treatment should be complete closure of the shunt. A complete cure by embolization is rather easily achieved in paraspinal lesions. Failure of endovascular therapy in dural or epidural shunts must bring the patient to surgery. The prognosis of most intradural shunts seems better than previously thought, even after haemorrhage. In intradural spinal cord arteriovenous shunts, embolisation

  13. Relationship of cerebral blood flow to aortic-to-pulmonary collateral/shunt flow in single ventricles.

    Science.gov (United States)

    Fogel, Mark A; Li, Christine; Wilson, Felice; Pawlowski, Tom; Nicolson, Susan C; Montenegro, Lisa M; Diaz Berenstein, Laura; Spray, Thomas L; Gaynor, J William; Fuller, Stephanie; Keller, Marc S; Harris, Matthew A; Whitehead, Kevin K; Clancy, Robert; Elci, Okan; Bethel, Jim; Vossough, Arastoo; Licht, Daniel J

    2015-08-01

    Patients with single ventricle can develop aortic-to-pulmonary collaterals (APCs). Along with systemic-to-pulmonary artery shunts, these structures represent a direct pathway from systemic to pulmonary circulations, and may limit cerebral blood flow (CBF). This study investigated the relationship between CBF and APC flow on room air and in hypercarbia, which increases CBF in patients with single ventricle. 106 consecutive patients with single ventricle underwent 118 cardiac magnetic resonance (CMR) scans in this cross-sectional study; 34 prior to bidirectional Glenn (BDG) (0.50±0.30 years old), 50 prior to Fontan (3.19±1.03 years old) and 34 3-9 months after Fontan (3.98±1.39 years old). Velocity mapping measured flows in the aorta, cavae and jugular veins. Analysis of variance (ANOVA) and multiple linear regression were used. Significance was pflow or body surface area, independent of age, cardiopulmonary bypass time, Po2 and Pco2 (R=-0.67--0.70 for all patients on room air, pflow was higher prior to BDG than in other stages. There is a strong inverse relationship between CBF and APC/shunt flow in patients with single ventricle throughout surgical reconstruction on room air and in hypercarbia independent of other factors. We speculate that APC/shunt flow may have a negative impact on cerebral development and neurodevelopmental outcome. Interventions on APC may modify CBF, holding out the prospect for improving neurodevelopmental trajectory. NCT02135081. 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.

  14. Generalized model of a bidirectional DC-DC converter

    Science.gov (United States)

    Hinov, Nikolay; Arnaudov, Dimitar; Penev, Dimitar

    2017-12-01

    The following paperwork presents models of bidirectional converters. A classic bidirectional converter and a new bidirectional circuit based on a ZCS resonant converter are investigated and compared. The developed models of these converters allow comparison between their characteristics showing their advantages and disadvantages. The models allow precise models of energy storage elements to be implemented as well, which is useful for examination of energy storage systems.

  15. Scoliosis and Syringomyelia With Chiari Malformation After Lumbar Shunting

    Directory of Open Access Journals (Sweden)

    Hsin-Hung Chen

    2010-07-01

    Full Text Available Unsteady gait was noted in a 2-year-old boy with a lumboperitoneal (LP shunt that had been inserted 1 year earlier for increased head circumference caused by communicating hydrocephalus. Scoliosis was also noted during postoperative follow-up. Magnetic resonance imaging revealed new hindbrain tonsillar herniation and an extensive syrinx from C3 to L1. The malfunctioning LP shunt was removed and posterior fossa decompression with ventriculoperitoneal shunt insertion was performed. The unsteady gait recovered completely and scoliosis improved. Magnetic resonance imaging demonstrated resolution of the syrinx and tonsillar herniation. Acquired Chiari I malformation after LP shunt is well documented; usually, patients have no symptoms. This is the first report to have all the cause and effect mechanisms among syringomyelia, scoliosis and Chiari I malformation in 1 patient. We review the literature and discuss the possible mechanisms.

  16. Optimization methods for the Train Unit Shunting Problem

    DEFF Research Database (Denmark)

    Haahr, Jørgen Thorlund; Lusby, Richard Martin; Wagenaar, Joris Camiel

    2017-01-01

    We consider the Train Unit Shunting Problem, an important planning problem for passenger railway operators. This problem entails assigning train units from shunting yards to scheduled train services in such a way that the resulting operations are without conflicts. The problem arises at every...... shunting yard in the railway network and involves matching train units to arriving and departing train services as well as assigning the selected matchings to appropriate shunting yard tracks. We present an extensive comparison benchmark of multiple solution approaches for this problem, some of which...... are novel. In particular, we develop a constraint programming formulation, a column generation approach, and a randomized greedy heuristic. We compare and benchmark these approaches with two existing methods, a mixed integer linear program and a two-stage heuristic. The benchmark contains multiple real...

  17. Epidural haematoma: pathophysiological significance of extravasation and arteriovenous shunting

    International Nuclear Information System (INIS)

    Habash, A.H.; Sortland, O.; Zwetnow, N.N.

    1982-01-01

    35 patients with epidural bleeding operated on at Rikshospitalet, Oslo, during the period 1965 - 1980 had preoperative angiography with visualization of the external carotid artery. Twenty-one patients had extravasation of contrast medium from meningeal arteries. Seventeen of the 21 had also shunting of contrast medium from meningeal arteries to meningeal or diploic veins, while 20 of the 21 also had bled from a ruptured meningeal artery at operation. It was further found that of 20 patients who deteriorated after trauma 18 had an epidural arteriovenous shunt or extravasation. Conversely, of 15 patients who improved after trauma 12 had no evidence of a shunt. The strong correlation between the clinical course and the occurrence of extravasation supports previous experimental and clinical data, indicating the epidural arteriovenous shunt to be a major factor in the pathophysiology and the outcome of epidural bleeding. (author)

  18. Bidirectional Relationship between Cognitive Function and Pneumonia

    Science.gov (United States)

    Shah, Faraaz Ali; Pike, Francis; Alvarez, Karina; Angus, Derek; Newman, Anne B.; Lopez, Oscar; Tate, Judith; Kapur, Vishesh; Wilsdon, Anthony; Krishnan, Jerry A.; Hansel, Nadia; Au, David; Avdalovic, Mark; Fan, Vincent S.; Barr, R. Graham

    2013-01-01

    Rationale: Relationships between chronic health conditions and acute infections remain poorly understood. Preclinical studies suggest crosstalk between nervous and immune systems. Objectives: To determine bidirectional relationships between cognition and pneumonia. Methods: We conducted longitudinal analyses of a population-based cohort over 10 years. We determined whether changes in cognition increase risk of pneumonia hospitalization by trajectory analyses and joint modeling. We then determined whether pneumonia hospitalization increased risk of subsequent dementia using a Cox model with pneumonia as a time-varying covariate. Measurements and Main Results: Of the 5,888 participants, 639 (10.9%) were hospitalized with pneumonia at least once. Most participants had normal cognition before pneumonia. Three cognition trajectories were identified: no, minimal, and severe rapid decline. A greater proportion of participants hospitalized with pneumonia were on trajectories of minimal or severe decline before occurrence of pneumonia compared with those never hospitalized with pneumonia (proportion with no, minimal, and severe decline were 67.1%, 22.8%, and 10.0% vs. 76.0%, 19.3%, and 4.6% for participants with and without pneumonia, respectively; P pneumonia, even in those with normal cognition and physical function before pneumonia (β = −0.02; P pneumonia were subsequently at an increased risk of dementia (hazard ratio, 2.24 [95% confidence interval, 1.62–3.11]; P = 0.01). Associations were independent of demographics, health behaviors, other chronic conditions, and physical function. Bidirectional relationship did not vary based on severity of disease, and similar associations were noted for those with severe sepsis and other infections. Conclusions: A bidirectional relationship exists between pneumonia and cognition and may explain how a single episode of infection in well-appearing older individuals accelerates decline in chronic health conditions and loss of

  19. TOOL ASSEMBLY WITH BI-DIRECTIONAL BEARING

    Science.gov (United States)

    Longhurst, G.E.

    1961-07-11

    A two-direction motion bearing which is incorporated in a refueling nuclear fuel element trsnsfer tool assembly is described. A plurality of bi- directional bearing assembliesare fixed equi-distantly about the circumference of the transfer tool assembly to provide the tool assembly with a bearing surface- for both axial and rotational motion. Each bi-directional bearing assembly contains a plurality of circumferentially bulged rollers mounted in a unique arrangement which will provide a bearing surface for rotational movement of the tool assembly within a bore. The bi-direc tional bearing assembly itself is capable of rational motion and thus provides for longitudinal movement of the tool assembly.

  20. Predistortion of a Bidirectional Cuk Audio Amplifier

    DEFF Research Database (Denmark)

    Birch, Thomas Hagen; Nielsen, Dennis; Knott, Arnold

    2014-01-01

    Some non-linear amplifier topologies are capable of providing a larger voltage gain than one from a DC source, which could make them suitable for various applications. However, the non-linearities introduce a significant amount of harmonic distortion (THD). Some of this distortion could be reduced...... using predistortion. This paper suggests linearizing a nonlinear bidirectional Cuk audio amplifier using an analog predistortion approach. A prototype power stage was built and results show that a voltage gain of up to 9 dB and reduction in THD from 6% down to 3% was obtainable using this approach....

  1. Multistability in bidirectional associative memory neural networks

    International Nuclear Information System (INIS)

    Huang Gan; Cao Jinde

    2008-01-01

    In this Letter, the multistability issue is studied for Bidirectional Associative Memory (BAM) neural networks. Based on the existence and stability analysis of the neural networks with or without delay, it is found that the 2n-dimensional networks can have 3 n equilibria and 2 n equilibria of them are locally exponentially stable, where each layer of the BAM network has n neurons. Furthermore, the results has been extended to (n+m)-dimensional BAM neural networks, where there are n and m neurons on the two layers respectively. Finally, two numerical examples are presented to illustrate the validity of our results

  2. Multistability in bidirectional associative memory neural networks

    Science.gov (United States)

    Huang, Gan; Cao, Jinde

    2008-04-01

    In this Letter, the multistability issue is studied for Bidirectional Associative Memory (BAM) neural networks. Based on the existence and stability analysis of the neural networks with or without delay, it is found that the 2 n-dimensional networks can have 3 equilibria and 2 equilibria of them are locally exponentially stable, where each layer of the BAM network has n neurons. Furthermore, the results has been extended to (n+m)-dimensional BAM neural networks, where there are n and m neurons on the two layers respectively. Finally, two numerical examples are presented to illustrate the validity of our results.

  3. Clinical outcomes of temporary shunting for infants with cerebral pseudomeningocele.

    Science.gov (United States)

    Mattei, Tobias A; Sambhara, Deepak; Bond, Brandon J; Lin, Julian

    2014-02-01

    Although in the case of subdural collections temporary shunting has been suggested as a viable alternative for definitive drainage of the accumulated fluid until restoration of the normal CSF dynamics, there is no agreement on the best management strategy for pseudomeningocele. The authors performed a retrospective chart review in order to evaluate the clinical outcomes of infants temporarily shunted for pseudomeningocele without encephalocele at our institution (The University of Illinois at Peoria/Illinois Neurological Institute) in the period from 2004 to 2012. The epidemiological characteristics, clinical management, and final outcomes of such subpopulation were compared with a control group which received temporary shunting for subdural hematomas (SDH) during the same period. Four patients (100% male) ranging in age from 8.9 to 27.1 months (mean = 13.88) with pseudomeningocele and 17 patients (64.7% male) ranging in age from 1.9 to 11.8 months (mean = 4.15) with SDH were identified. Although the initial management included sequential percutaneous subdural tapping in 82% of the patients, all children ultimately failed such strategy, requiring either subdural-peritoneal (81% of the cases) or subgaleal-peritoneal (19% of the cases) shunting. The mean implant duration was 201 days for the pseudomeningocele group and 384 days for the SDH one. Mean post-shunt hospitalization was 2 days for patients with pseudomeningocele and 4 days for patients with SDH. There was no statistical difference in terms of complications, length of hospitalization post-shunting, or clinical outcomes between the patients with pseudomeningocele and those with SDH. Temporary shunting of infants with pseudo-meningocele constitutes a viable therapeutic alternative with favorable clinical outcomes and a low risk of shunt dependency similar to those of children with SDH.

  4. Cross-species functionality of pararetroviral elements driving ribosome shunting.

    Directory of Open Access Journals (Sweden)

    Mikhail M Pooggin

    Full Text Available BACKGROUND: Cauliflower mosaic virus (CaMV and Rice tungro bacilliform virus (RTBV belong to distinct genera of pararetroviruses infecting dicot and monocot plants, respectively. In both viruses, polycistronic translation of pregenomic (pg RNA is initiated by shunting ribosomes that bypass a large region of the pgRNA leader with several short (sORFs and a stable stem-loop structure. The shunt requires translation of a 5'-proximal sORF terminating near the stem. In CaMV, mutations knocking out this sORF nearly abolish shunting and virus viability. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that two distant regions of the CaMV leader that form a minimal shunt configuration comprising the sORF, a bottom part of the stem, and a shunt landing sequence can be replaced by heterologous sequences that form a structurally similar configuration in RTBV without any dramatic effect on shunt-mediated translation and CaMV infectivity. The CaMV-RTBV chimeric leader sequence was largely stable over five viral passages in turnip plants: a few alterations that did eventually occur in the virus progenies are indicative of fine tuning of the chimeric sequence during adaptation to a new host. CONCLUSIONS/SIGNIFICANCE: Our findings demonstrate cross-species functionality of pararetroviral cis-elements driving ribosome shunting and evolutionary conservation of the shunt mechanism. We are grateful to Matthias Müller and Sandra Pauli for technical assistance. This work was initiated at Friedrich Miescher Institute (Basel, Switzerland. We thank Prof. Thomas Boller for hosting the group at the Institute of Botany.

  5. Treatment of Hydrocephalus Associated with Neurosarcoidosis by Multiple Shunt Placement

    OpenAIRE

    Kim, Sung Hoon; Lee, Sang Weon; Sung, Soon Ki; Son, Dong Wuk

    2012-01-01

    A 31-year-old man was admitted to our hospital due to hydrocephalus with neurosarcoidosis. Ventriculo-peritoneal shunting was performed in the right lateral ventricle with intravenous methylprednisolone. Subsequently, after 4 months, additional ventriculo-peritoneal shunting in the left lateral ventricle was performed due to the enlarged left lateral ventricle and slit-like right lateral ventricle. After 6 months, he was re-admitted due to upward gaze palsy, and magnetic resonance image showe...

  6. Transluminal angioplasty of a stenotic surgical splenorenal shunt

    International Nuclear Information System (INIS)

    Beers, B. van; Roche, A.; Cauquil, P.

    1988-01-01

    A stenosis of a side-to-side splenorenal shunt was treated by percutaneous angioplasty two years after the performance of the shunt. After dilatation, there was a fall of the splenorenal pressure gradient from 28 to 17 cm H 2 O and good transanastomotic flow was re-estabilshed. As in other arterial and venous territories, angioplasty may be an interesting alternative to surgery. (orig.)

  7. Assessment Lumboperitoneal or Ventriculoperitoneal Shunt Patency by Radionuclide Technique: A Review Experience Cases

    International Nuclear Information System (INIS)

    Chiewvit, Sunanta; Nuntaaree, Sarun; Kanchaanapiboon, Potjanee; Chiewvit, Pipat

    2014-01-01

    Hydrocephalus-related symptoms that worsen after shunt placement may indicate a malfunctioning or obstructed shunt. The assessment of shunt patency and site of obstruction is important for planning of treatment. The radionuclide cerebrospinal fluid (CSF) shunt study provides a simple, effective, and low-radiation-dose method of assessing CSF shunt patency. The radionuclide CSF shuntography is a useful tool in the management of patients presenting with shunt-related problems not elucidated by conventional radiological examination. This article described the imaging technique of ventriculoperitoneal (VP) shunt and lumbar puncture (LP) shunt. The normal finding, abnormal finding of completed obstruction and partial obstruction is present by our cases experience. The radiopharmaceutical (Tc-99m diethylenetriaminepentaacetic acid) was injected via the reservoir for VP shunt and via lumbar puncture needle in subarachnoid space for LP shunt, then serial image in the head and abdominal area. The normal function of VP and LP shunt usually rapid spillage of the radioactivity in the abdominal cavity diffusely. The patent proximal tube VP shunt demonstrates ventricular reflux. The early image of patent LP shunt reveals no activity in the ventricular system contrast to distal LP shunt reveals early reflux of activity in the ventricular system. The completed distal VP and LP shunt obstruction show absence of tracer in the peritoneal area or markedly delayed appearance of abdominal activity. The partial distal VP and LP shunt obstruction recognized by slow transit or accumulation of tracer at the distal end or focal tracer in the peritoneal cavity near the tip of distal shunt. The images of the normal and abnormal CSF shunt as describe before are present in the full paper. Radionuclide CSF shuntography is a reliable and simple procedure for assessment shunt patency

  8. Resident-performed Ex-PRESS shunt implantation versus trabeculectomy.

    Science.gov (United States)

    Seider, Michael I; Rofagha, Soraya; Lin, Shan C; Stamper, Robert L

    2012-09-01

    To compare outcomes between resident-performed trabeculectomy and Ex-PRESS shunt implantation. A consecutive cohort of 36 Ex-PRESS shunt implantations and 57 trabeculectomies (1 eye/patient) performed by resident surgeons in their third year of ophthalmic training at the University of California, San Francisco and at the San Francisco Veterans Administration Hospital, under the supervision of a single glaucoma fellowship-trained surgeon were included in this study. Eyes with PRESS shunt groups at all follow-up points. On average, the Ex-PRESS shunt group required significantly less ocular antihypertensive medication to control IOP at 3 months postoperative (P=0.01), but no difference was found at 6 months or 1 year (all, P≥0.28). A larger proportion of Ex-PRESS shunt patients had good IOP control without medication at 3 (P=0.057) and 6 months (P=0.076) postoperatively. No difference was found in the rates of sight-threatening complications between groups (all, P≥0.22). In the hands of ophthalmology residents in their third year of training, the trabeculectomy and Ex-PRESS shunt implantation procedures perform comparably in terms of postoperative IOP control, reduction in patient dependence on ocular antihypertensive medications, and risk of complication in our population.

  9. Personalized recommendation based on heat bidirectional transfer

    Science.gov (United States)

    Ma, Wenping; Feng, Xiang; Wang, Shanfeng; Gong, Maoguo

    2016-02-01

    Personalized recommendation has become an increasing popular research topic, which aims to find future likes and interests based on users' past preferences. Traditional recommendation algorithms pay more attention to forecast accuracy by calculating first-order relevance, while ignore the importance of diversity and novelty that provide comfortable experiences for customers. There are some levels of contradictions between these three metrics, so an algorithm based on bidirectional transfer is proposed in this paper to solve this dilemma. In this paper, we agree that an object that is associated with history records or has been purchased by similar users should be introduced to the specified user and recommendation approach based on heat bidirectional transfer is proposed. Compared with the state-of-the-art approaches based on bipartite network, experiments on two benchmark data sets, Movielens and Netflix, demonstrate that our algorithm has better performance on accuracy, diversity and novelty. Moreover, this method does better in exploiting long-tail commodities and cold-start problem.

  10. Bidirectional telemetry controller for neuroprosthetic devices.

    Science.gov (United States)

    Sharma, Vishnu; McCreery, Douglas B; Han, Martin; Pikov, Victor

    2010-02-01

    We present versatile multifunctional programmable controller with bidirectional data telemetry, implemented using existing commercial microchips and standard Bluetooth protocol, which adds convenience, reliability, and ease-of-use to neuroprosthetic devices. Controller, weighing 190 g, is placed on animal's back and provides bidirectional sustained telemetry rate of 500 kb/s , allowing real-time control of stimulation parameters and viewing of acquired data. In continuously-active state, controller consumes approximately 420 mW and operates without recharge for 8 h . It features independent 16-channel current-controlled stimulation, allowing current steering; customizable stimulus current waveforms; recording of stimulus voltage waveforms and evoked neuronal responses with stimulus artifact blanking circuitry. Flexibility, scalability, cost-efficiency, and a user-friendly computer interface of this device allow use in animal testing for variety of neuroprosthetic applications. Initial testing of the controller has been done in a feline model of brainstem auditory prosthesis. In this model, the electrical stimulation is applied to the array of microelectrodes implanted in the ventral cochlear nucleus, while the evoked neuronal activity was recorded with the electrode implanted in the contralateral inferior colliculus. Stimulus voltage waveforms to monitor the access impedance of the electrodes were acquired at the rate of 312 kilosamples/s. Evoked neuronal activity in the inferior colliculus was recorded after the blanking (transient silencing) of the recording amplifier during the stimulus pulse, allowing the detection of neuronal responses within 100 mus after the end of the stimulus pulse applied in the cochlear nucleus.

  11. Programmable shunts and headphones: Are they safe together?

    Science.gov (United States)

    Spader, Heather S; Ratanaprasatporn, Linda; Morrison, John F; Grossberg, Jonathan A; Cosgrove, G Rees

    2015-10-01

    Programmable shunts have a valuable role in the treatment of patients with hydrocephalus, but because a magnet is used to change valve settings, interactions with external magnets may reprogram these shunts. Previous studies have demonstrated the ability of magnetic toys and iPads to erroneously reprogram shunts. Headphones are even more ubiquitous, and they contain an electromagnet for sound projection that sits on the head very close to the shunt valve. This study is the first to look at the magnetic field emissions of headphones and their effect on reprogrammable shunt valves to ascertain whether headphones are safe for patients with these shunts to wear. In this in vitro study of the magnetic properties of headphones and their interactions with 3 different programmable shunts, the authors evaluated Apple earbuds, Beats by Dr. Dre, and Bose QuietComfort Acoustic Noise Cancelling headphones. Each headphone was tested for electromagnetic field emissions using a direct current gaussmeter. The following valves were evaluated: Codman Hakim programmable valve, Medtronic Strata II valve, and Aesculap proGAV. Each valve was tested at distances of 0 to 50 mm (in 5-mm increments) from each headphone. The exposure time at each distance was 1 minute, and 3 trials were performed to confirm results at each valve setting and distance. All 3 headphones generated magnetic fields greater than the respective shunt manufacturer's recommended strength of exposure, but these fields did not persist beyond 5 mm. By 2 cm, the fields levels were below 20 G, well below the Medtronic recommendation of 90 G and the Codman recommendation of 80 G. Because the mechanism for the proGAV is different, there is no recommended gauss level. There was no change in gauss-level emissions by the headphones with changes in frequency and amplitude. Both the Strata and Codman-Hakim valves were reprogrammed by direct contact (distance 0 mm) with the Bose headphones. When a rotation component was added, all

  12. Shape Optimization of the Assisted Bi-directional Glenn surgery for stage-1 single ventricle palliation

    Science.gov (United States)

    Verma, Aekaansh; Shang, Jessica; Esmaily-Moghadam, Mahdi; Wong, Kwai; Marsden, Alison

    2016-11-01

    Babies born with a single functional ventricle typically undergo three open-heart surgeries starting as neonates. The first of these stages (BT shunt or Norwood) has the highest mortality rates of the three, approaching 30%. Proceeding directly to a stage-2 Glenn surgery has historically demonstrated inadequate pulmonary flow (PF) & high mortality. Recently, the Assisted Bi-directional Glenn (ABG) was proposed as a promising means to achieve a stable physiology by assisting the PF via an 'ejector pump' from the systemic circulation. We present preliminary parametrization and optimization results for the ABG geometry, with the goal of increasing PF. To limit excessive pressure increases in the Superior Vena Cava (SVC), the SVC pressure is included as a constraint. We use 3-D finite element flow simulations coupled with a single ventricle lumped parameter network to evaluate PF & the pressure constraint. We employ a derivative free optimization method- the Surrogate Management Framework, in conjunction with the OpenDIEL framework to simulate multiple simultaneous evaluations. Results show that nozzle diameter is the most important design parameter affecting ABG performance. The application of these results to patient specific situations will be discussed. This work was supported by an NSF CAREER award (OCI1150184) and by the XSEDE National Computing Resource.

  13. Bidirectional magnetic microactuators for uTAS

    Science.gov (United States)

    Hilbich, Daniel D.; Khosla, Ajit; Gray, Bonnie L.; Shannon, Lesley

    2011-02-01

    We present the design, fabrication and characterization of a novel bidirectional magnetic microactuator. The actuator has a planar structure and is easily fabricated using processes based on laser micromachining and soft lithography, allowing it to be readily integrated into microfluidic, microelectromechanical systems (MEMS) and lab-on-a-chip (LOC) designs. The new microactuator is a thin magnetic membrane with a central magnet feature. The membrane and magnet are both composed of a magnetic nanocomposite polymer (M-NCP) material that is fabricated by embedding magnetic powder in a polydimethysiloxane (PDMS) polymer matrix. The magnetic powder (MQP-12-5) has the chemical composition of (Nd0.7Ce0.3)10.5Fe83.9B5.6, and contains grains that are 5-6 microns in size. The powder is uniformly dispersed at a weight percentage of 75 wt-% in the PDMS matrix, and micropatterned using soft lithography micromolding to realize magnetic microstructures, which sit on a thinner magnetic PDMS membrane of the same material. The molds are fabricated by laser-etching into Poly (methyl methacrylate) (PMMA) using a Universal Laser System's VersaLASERlaser ablation system. The PDMS-based M-NCP is then poured and spun over the mold patterns, producing a thin polymer membrane to which the polymer micromagnets are attached, forming a one-piece actuator. The M-NCP is initially un-magnetized, but is then magnetized by placing it in a 2.5T magnetic field to produce permanent bidirectional magnetization that is polarized in the specified direction. To characterize the bidirectional actuators, a uniform magnetic field is established via a Helmholtz coil pair, and is characterized by applying varying currents. The magnetic field (and thus the actuator deflection) is controlled by regulating the current in the Helmholtz pair. Using this apparatus, deflection versus field characteristics are obtained, with maximum deflections varying as a function of actuator dimensions and the applied magnetic

  14. Outcomes of systemic to pulmonary artery shunts in patients weighing less than 3 kg: analysis of shunt type, size, and surgical approach.

    Science.gov (United States)

    Myers, John W; Ghanayem, Nancy S; Cao, Yumei; Simpson, Pippa; Trapp, Katie; Mitchell, Michael E; Tweddell, James S; Woods, Ronald K

    2014-02-01

    To evaluate outcomes of systemic to pulmonary artery shunts (SPS) in patients weighing less than 3 kg with regard to shunt type, shunt size, and surgical approach. Patients weighing less than 3 kg who underwent modified Blalock-Taussig or central shunts with polytetrafluoroethylene grafts at our institution from January 1, 2000, to May 31, 2011, were reviewed. Patients who had undergone other major concomitant procedures were excluded from the analysis. Primary outcomes included mortality (discharge mortality and mortality before next planned palliative procedure or definitive repair), cardiac arrest and/or extracorporeal membrane oxygenation (ECMO), and shunt reintervention. In this cohort of 80 patients, discharge survival was 96% (77/80). Postoperative cardiac arrest or ECMO occurred in 6/80 (7.5%), and shunt reintervention was required in 14/80 (17%). On univariate analysis, shunt reintervention was more common in patients with 3-mm shunts (11/30, 37%) compared with 3.5-mm (2/36, 6%) or 4-mm shunts (1/14, 7%) (P approach and cardiac arrest/ECMO or mortality. Multiple logistic regression demonstrated that a shunt size of 3 mm (P = .019) and extracardiac anomaly (P = .047) were associated with shunt reintervention, whereas no variable was associated with cardiac arrest/ECMO or mortality. In this high-risk group of neonates weighing less than 3 kg at the time of SPS, survival to discharge and the next planned surgical procedure was high. Outcomes were good with the 3.5- and 4-mm shunts; however, shunt reintervention was common with 3-mm shunts. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  15. Bidirectional Telemetry Controller for Neuroprosthetic Devices

    Science.gov (United States)

    Sharma, Vishnu; McCreery, Douglas B.; Han, Martin; Pikov, Victor

    2010-01-01

    We present versatile multifunctional programmable controller with bidirectional data telemetry, implemented using existing commercial microchips and standard Bluetooth protocol, which adds convenience, reliability, and ease-of-use to neuroprosthetic devices. Controller, weighing 190 g, is placed on animal's back and provides bidirectional sustained telemetry rate of 500 kb/s, allowing real-time control of stimulation parameters and viewing of acquired data. In continuously-active state, controller consumes ∼420 mW and operates without recharge for 8 h. It features independent 16-channel current-controlled stimulation, allowing current steering; customizable stimulus current waveforms; recording of stimulus voltage waveforms and evoked neuronal responses with stimulus artifact blanking circuitry. Flexibility, scalability, cost-efficiency, and a user-friendly computer interface of this device allow use in animal testing for variety of neuroprosthetic applications. Initial testing of the controller has been done in a feline model of brainstem auditory prosthesis. In this model, the electrical stimulation is applied to the array of microelectrodes implanted in the ventral cochlear nucleus, while the evoked neuronal activity was recorded with the electrode implanted in the contralateral inferior colliculus. Stimulus voltage waveforms to monitor the access impedance of the electrodes were acquired at the rate of 312 kilosamples/s. Evoked neuronal activity in the inferior colliculus was recorded after the blanking (transient silencing) of the recording amplifier during the stimulus pulse, allowing the detection of neuronal responses within 100 μs after the end of the stimulus pulse applied in the cochlear nucleus. PMID:19933010

  16. A Modified Shunt System for the Management of Pyogenic Hydrocephalus

    Directory of Open Access Journals (Sweden)

    Abdul Naveed Khan

    2017-01-01

    Full Text Available BACKGROUND: To describe the structure and efficacy of a modified cerebrospinal fluid (CSF shunt system with Bhatti CSF access chamber and ventriculoperitoneal shunt, for the management of hydrocephalus associated with pyogenic ventriculitis. METHODS: This was an observational study performed at the National Medical Center and Ziauddin Medical University, Karachi, Pakistan. Chemically bonded Bhatti CSF access chamber and ventriculoperitoneal shunt was inserted into 443 patients with hydrocephalus and pyogenic ventriculitis to allow injection of antibiotics into the lateral ventricles. RESULTS: In all patients, symptoms and signs of hydrocephalus were relieved immediately after shunt insertion and infection brought under control within two weeks of intraventricular injection of antibiotics (vancomycin or linezolid, via the CSF access chamber. In two patients peritoneal catheter was blocked by a precipitate of vancomycin. Reduction in the dose of intraventricular vancomycin from 50mg to 20mg and increased dilution (additional 2ml of 0.9% N/S solution prevented recurrence of this complication. All patients recovered from ventriculitis within two weeks of initiating this treatment. Follow-up was from 3 months to 2 years to monitor continued relief of hydrocephalus and absence of recurrence of ventriculitis. CONCLUSION: Bhatti CSF access chamber and the ventriculoperitoneal shunt is the only system available at present that fulfills the management of hydrocephalus associated with pyogenic ventriculitis. It provides continuous internal drainage of CSF combined with access to the ventricles for injection of antibiotics.

  17. Determining the optimal portal blood volume in a shunt before surgery in extrahepatic portal hypertension

    Directory of Open Access Journals (Sweden)

    Yurchuk Vladimir A

    2016-04-01

    Full Text Available The aim of the study: To determine the necessary shunt diameter and assess the optimal portal blood volume in a shunt in children with extrahepatic portal hypertension before the portosystemic shunt surgery. Changes in the liver hemodynamics were studied in 81 children aged from 4 to 7 years with extrahepatic portal hypertension. We established that it is necessary to calculate the shunt diameter and the blood volume in a shunt in patients with extrahepatic portal hypertension before the portosystemic shunt surgery. It allows us to preserve the hepatic portal blood flow and effectively decrease the pressure in the portal system. Portosystemic shunt surgery in patients with extrahepatic portal hypertension performed in accordance with the individualized shunt volume significantly decreases portal pressure, preserves stable hepatic hemodynamics and prevents gastro-esophageal hemorrhage.

  18. Post V-P shunt surgical site EDH an uncommon complication: case report

    Directory of Open Access Journals (Sweden)

    Garg Manish

    2017-06-01

    Full Text Available ventriculoparitoneal shunt is well established modality of treatment for hydrocephalous. Complication of v-p shunt are also mentioned in literature like shunt infection shunt migration etc [8]. Here we are describing a rare complication of vp shunt which barely mentioned in literature. A 22 yr male admitted with complain of headache & vomiting patient was diagnosed to have tubercular meningities with hydrocephalous. Patient planned for ventriculoparietoneal shunt surgery and vp shunt was done. On 3rd post-surgery day patient develop weakness in Left side of body. Urgent ncct head done which showed EDH at surgical site. Immediate craniotomy and evacuation of hematoma was done patient improved and discharged. Thus we are discussing the importance of meticulous surgery for v-p shunt, post op ct scan and treatment.

  19. Shunted-Josephson-junction model. II. The nonautonomous case

    DEFF Research Database (Denmark)

    Belykh, V. N.; Pedersen, Niels Falsig; Sørensen, O. H.

    1977-01-01

    The shunted-Josephson-junction model with a monochromatic ac current drive is discussed employing the qualitative methods of the theory of nonlinear oscillations. As in the preceding paper dealing with the autonomous junction, the model includes a phase-dependent conductance and a shunt capacitance....... The mathematical discussion makes use of the phase-space representation of the solutions to the differential equation. The behavior of the trajectories in phase space is described for different characteristic regions in parameter space and the associated features of the junction IV curve to be expected are pointed...... out. The main objective is to provide a qualitative understanding of the junction behavior, to clarify which kinds of properties may be derived from the shunted-junction model, and to specify the relative arrangement of the important domains in the parameter-space decomposition....

  20. Secondary pediatric encephalocele after ventriculosubgaleal shunting for posthemorrhagic hydrocephalus.

    Science.gov (United States)

    Seeburg, Daniel; Ahn, Edward; Huisman, Thierry

    2014-08-01

    Intraventricular hemorrhage and posthemorrhagic hydrocephalus continue to be common complications in very low-birth-weight premature infants, often requiring ventricular shunting for cerebrospinal fluid diversion. We report on two infants with posthemorrhagic hydrocephalus that developed a secondary encephalocele after ventriculosubgaleal shunting. Encephaloceles can act as a source of seizure activity and can result in various additional complications including meningitis, abscess formation, and infarction of herniated brain parenchyma. With continued improvements in neonatal intensive care, the survival of infants with significant medical comorbidities-including those that develop posthemorrhagic hydrocephalus requiring ventricular shunting-continues to increase. It is thus important for the radiologist and treating physician to be aware of this rare, potential complication. Georg Thieme Verlag KG Stuttgart · New York.

  1. Forty years of shunt surgery at Rigshospitalet, Denmark

    DEFF Research Database (Denmark)

    Mansson, Philip Kofoed; Johansson, Sofia; Ziebell, Morten

    2017-01-01

    Objective The objective of this study is to review our experience of shunt surgery by investigating 40years of development in terms of rates of revision and infection, shunt survival and risk factors. Design and participants Medical records and operative reports were reviewed retrospectively...... for all patients who underwent primary shunt surgery at our department in the years 2010 to 2012. All results were compared with a previous study from our department. A mixed population consisting of 434 patients was included. Adults (≥15years) accounted for 89.9% of all patients and the mean follow.......1-54.9). Within 4weeks postoperatively, 3.2% had an infection and overall infection rate was 5.5%. Short duration of surgery and the use of antibiotic prophylaxis were associated with a lower risk of infection. The most frequent causes of revision were valve defects (18.4%) and proximal defects or obstructions...

  2. Shunt impedance of spiral loaded resonant rf cavities

    International Nuclear Information System (INIS)

    Peebles, P.Z. Jr.; Parvarandeh, M.

    1975-01-01

    Based upon a treatment of the spiral loaded resonant radio frequency cavity as a shorted quarter-wave transmission line, a model for shunt impedance is developed. The model is applicable to loosely wound spirals in large diameter containers. Theoretical shunt impedance is given for spirals wound from tubing of circular or rectangular cross section. The former produces higher shunt impedance. Measurements made at Oak Ridge National Laboratory on 17 copper cavities are described which support the theoretical results. Theoretical results are also compared to data from twenty-three additional cavities measured at Los Alamos Scientific Laboratory. It is shown that the theoretical function forms a useful means of interpreting the quality of constructed cavities. (author)

  3. Treatment of hydrocephalus associated with neurosarcoidosis by multiple shunt placement.

    Science.gov (United States)

    Kim, Sung Hoon; Lee, Sang Weon; Sung, Soon Ki; Son, Dong Wuk

    2012-09-01

    A 31-year-old man was admitted to our hospital due to hydrocephalus with neurosarcoidosis. Ventriculo-peritoneal shunting was performed in the right lateral ventricle with intravenous methylprednisolone. Subsequently, after 4 months, additional ventriculo-peritoneal shunting in the left lateral ventricle was performed due to the enlarged left lateral ventricle and slit-like right lateral ventricle. After 6 months, he was re-admitted due to upward gaze palsy, and magnetic resonance image showed an isolated fourth ventricle with both the inlet and outlet of fourth ventricle obstructed by recurrent neurosarcoidosis. Owing to the difficulty of using an endoscope, we performed neuronavigator-guided ventriculo-peritoneal shunting via the left lateral transcerebellar approach for the treatment of the isolated fourth ventricle with intravenous methyl prednisolone. The patient was discharged with improved neurological status.

  4. Treatment of Portosystemic Shunt Myelopathy with a Stent Graft Deployed through a Transjugular Intrahepatic Route

    International Nuclear Information System (INIS)

    Jain, Deepak; Arora, Ankur; Deka, Pranjal; Mukund, Amar; Bhatnagar, Shorav; Jindal, Deepti; Kumar, Niteen; Pamecha, Viniyendra

    2013-01-01

    A case of surgically created splenorenal shunt complicated with shunt myelopathy was successfully managed by placement of a stent graft within the splenic vein to close the portosystemic shunt and alleviate myelopathy. To our knowledge, this is the first report of a case of shunt myelopathy in a patient with noncirrhotic portal fibrosis without cirrhosis treated by a novel technique wherein a transjugular intrahepatic route was adopted to deploy the stent graft

  5. Shunted Piezoelectric Vibration Damping Analysis Including Centrifugal Loading Effects

    Science.gov (United States)

    Min, James B.; Duffy, Kirsten P.; Provenza, Andrew J.

    2011-01-01

    Excessive vibration of turbomachinery blades causes high cycle fatigue problems which require damping treatments to mitigate vibration levels. One method is the use of piezoelectric materials as passive or active dampers. Based on the technical challenges and requirements learned from previous turbomachinery rotor blades research, an effort has been made to investigate the effectiveness of a shunted piezoelectric for the turbomachinery rotor blades vibration control, specifically for a condition with centrifugal rotation. While ample research has been performed on the use of a piezoelectric material with electric circuits to attempt to control the structural vibration damping, very little study has been done regarding rotational effects. The present study attempts to fill this void. Specifically, the objectives of this study are: (a) to create and analyze finite element models for harmonic forced response vibration analysis coupled with shunted piezoelectric circuits for engine blade operational conditions, (b) to validate the experimental test approaches with numerical results and vice versa, and (c) to establish a numerical modeling capability for vibration control using shunted piezoelectric circuits under rotation. Study has focused on a resonant damping control using shunted piezoelectric patches on plate specimens. Tests and analyses were performed for both non-spinning and spinning conditions. The finite element (FE) shunted piezoelectric circuit damping simulations were performed using the ANSYS Multiphysics code for the resistive and inductive circuit piezoelectric simulations of both conditions. The FE results showed a good correlation with experimental test results. Tests and analyses of shunted piezoelectric damping control, demonstrating with plate specimens, show a great potential to reduce blade vibrations under centrifugal loading.

  6. Percutaneous gastrostomy tube placement in patients with ventriculoperitoneal shunts

    Energy Technology Data Exchange (ETDEWEB)

    Sane, S.S.; Towbin, A.; Bergey, E.A.; Kaye, R.D.; Fitz, C.R.; Albright, L.; Towbin, R.B. [Department of Radiology, Children`s Hospital of Pittsburgh, 3705 Fifth Avenue, Pittsburgh, PA 15213 (United States)

    1998-07-01

    Objective. The purpose of this study is to determine the risk of CNS and/or peritoneal infection in children with ventriculoperitoneal shunts in whom a percutaneous gastrostomy tube is placed. Materials and methods. We placed 205 gastrostomy or gastrojejunostomy tubes from January of 1991 to December 1996. Twenty-three patients (10 boys, 13 girls) had ventriculoperitoneal shunts at the time of placement. All shunts were placed at least 1 month prior to placement of the gastrostomy tube. The patients ranged in age from 8 months to 16 years with a mean age of 6 years, 9 months. Patient weight ranged from 2 kg to 60 kg. All 23 children required long-term nutritional support due to severe neurologic impairment. No prophylactic antibiotics were given prior to the procedure. Of the patients, 21/23 had a 14-F Sacks-Vine gastrostomy tube with a fixed terminal retention device inserted, using percutaneous fluoroscopic antegrade technique. Two of the 23 patients had a Ross 14-F Flexi-flo gastrostomy tube which required a retrograde technique due to a small caliber esophagus in these children. Results. All 23 children had technically successful placements of percutaneous gastrostomy (7) or gastrojejunostomy (16) tubes. Of the children, 21/23 (91 %) had no complications from the procedure. Two of 23 (9 %) patients demonstrated signs of peritonitis after placement of their gastrostomy tubes and subsequently had shunt infections. In both, children CSF culture grew gram-positive cocci. The antegrade technique was used in both children who developed peritonitis. Conclusion. Our study indicates children with ventriculoperitoneal shunts who undergo percutaneous gastrostomy are at greater risk for infection and subsequent shunt malfunction. Therefore, we recommend prophylactic antibiotic therapy to cover for skin and oral flora. (orig.) With 1 fig., 7 refs.

  7. Measurement of shunt amount using radionuclide angiocardiography: accuracy according to level of shunt and associated lesion

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yang Min [Sejong General Hospital, Bucheon (Korea, Republic of)

    2006-08-15

    Determination of pulmonary to systemic blood flow ratio (QP/QS) is important for the management of patients with left-to-right shunt. This study was performed to assess the agreement of Qp/Qs ratio using the radionuclide method and oxymetry, to investigate the factors influencing the agreement, and to know how interchangeable the results of each technique. We compared the Qp/Qs measured by single-pass radionuclide angiocardiography and oxymetry during catheterization in 207 patients who underwent both studies. In radionuclide method, Qp/Qs was calculated from the pulmonary time-activity curves using a gamma variate fit. The correlation and Bland-Altman analysis were performed according to the levels of shunt and associated lesions. The mean Qp/Qs was 1.83 {+-} 0.50 by radionuclide, and 1.74 {+-} 0.51 by oxymetry. The overall correlation coefficient was 0.86 ({rho} 0.001), and Bland-Altman range of agreement encompassing 4SD was 1.05. For atrial septal defect, ventricular septal defect, patent ductus arteriosus, tricuspid and mitral insufficiency, the correlation coefficient was 0.78, 0.90, 0.84, 0.63 and 0.44 and Bland-Altman range was 1.52, 0.74, 0.96, 1.57 and 1.50, respectively. There is good agreement but wide variance between the Qp/Qs ratios by radionuclide method and oxymetry. Associated atrioventricular valvar insufficiency decreases the correlation coefficient and widens the variance. Wide overall variance suggests that Qp/Qs measurements by two techniques should not be used interchangeably.

  8. Measurement of shunt amount using radionuclide angiocardiography: accuracy according to level of shunt and associated lesion

    International Nuclear Information System (INIS)

    Kim, Yang Min

    2006-01-01

    Determination of pulmonary to systemic blood flow ratio (QP/QS) is important for the management of patients with left-to-right shunt. This study was performed to assess the agreement of Qp/Qs ratio using the radionuclide method and oxymetry, to investigate the factors influencing the agreement, and to know how interchangeable the results of each technique. We compared the Qp/Qs measured by single-pass radionuclide angiocardiography and oxymetry during catheterization in 207 patients who underwent both studies. In radionuclide method, Qp/Qs was calculated from the pulmonary time-activity curves using a gamma variate fit. The correlation and Bland-Altman analysis were performed according to the levels of shunt and associated lesions. The mean Qp/Qs was 1.83 ± 0.50 by radionuclide, and 1.74 ± 0.51 by oxymetry. The overall correlation coefficient was 0.86 (ρ 0.001), and Bland-Altman range of agreement encompassing 4SD was 1.05. For atrial septal defect, ventricular septal defect, patent ductus arteriosus, tricuspid and mitral insufficiency, the correlation coefficient was 0.78, 0.90, 0.84, 0.63 and 0.44 and Bland-Altman range was 1.52, 0.74, 0.96, 1.57 and 1.50, respectively. There is good agreement but wide variance between the Qp/Qs ratios by radionuclide method and oxymetry. Associated atrioventricular valvar insufficiency decreases the correlation coefficient and widens the variance. Wide overall variance suggests that Qp/Qs measurements by two techniques should not be used interchangeably

  9. Isolation and characterization of Salmonella typhimurium glyoxylate shunt mutants.

    OpenAIRE

    Wilson, R B; Maloy, S R

    1987-01-01

    Growth of Salmonella typhimurium on acetate as a sole carbon source requires expression of the glyoxylate shunt; however, the genes for the glyoxylate shunt enzymes have not been previously identified in S. typhimurium. In this study, we isolated transposon insertions in the genes for the two unique enzymes of this pathway, aceA (isocitrate lyase) and aceB (malate synthase). The aceA and aceB genes were located at 89.5 min on the S. typhimurium genetic map. Genetic linkage to nearby loci indi...

  10. Controversy about Management of Hydrocephalus - Shunt vs. Endoscopic Third Ventriculostomy.

    Science.gov (United States)

    Kumar, Vikas; Bodeliwala, Shaam; Singh, Daljit

    2017-08-01

    The best management of hydrocephalus is still controversial in the twenty-first century. Shunt treatment for hydrocephalus is the most common procedure performed in neurosurgical practice and is associated with the highest complications rate. But during the last 2 decades, the treatment of hydrocephalus has improved with better shunt devices available today, increased facilities for investigations and newer approaches like endoscopic third ventriculostomy. The recent advances in development of better endoscopes have provided the patient and treating doctor with an option for an alternative surgery for treatment of hydrocephalus.

  11. Cryptococcal cerebrospinal fluid shunt infection treated with fluconazole

    Directory of Open Access Journals (Sweden)

    Daniel Eymard

    1993-01-01

    Full Text Available A 37-year-old woman with a cadaveric renal allotransplantation required intra-cranial shunting devices after a presumptive episode of tuberculous meningitis. Six months later, she developed a culture-proven cryptococcal meningitis. Without having her ventriculo-auricular shunt removed, she was successfully treated with a short course of amphotericin B (335 mg and flucytosine (nine days followed by prolonged therapy with oral fluconazole (400 mg daily for 72 days. Three years post treatment she had no evidence of relapse, and normal renal graft function.

  12. New and improved ways to treat hydrocephalus: Pursuit of a smart shunt.

    Science.gov (United States)

    Lutz, Barry R; Venkataraman, Pranav; Browd, Samuel R

    2013-01-01

    The most common treatment for hydrocephalus is placement of a cerebrospinal fluid shunt to supplement or replace lost drainage capacity. Shunts are life-saving devices but are notorious for high failure rates, difficulty of diagnosing failure, and limited control options. Shunt designs have changed little since their introduction in 1950s, and the few changes introduced have had little to no impact on these long-standing problems. For decades, the community has envisioned a "smart shunt" that could provide advanced control, diagnostics, and communication based on implanted sensors, feedback control, and telemetry. The most emphasized contribution of smart shunts is the potential for advanced control algorithms, such as weaning from shunt dependency and personalized control. With sensor-based control comes the opportunity to provide data to the physician on patient condition and shunt function, perhaps even by a smart phone. An often ignored but highly valuable contribution would be designs that correct the high failure rates of existing shunts. Despite the long history and increasing development activity in the past decade, patients are yet to see a commercialized smart shunt. Most smart shunt development focuses on concepts or on isolated technical features, but successful smart shunt designs will be a balance between technical feasibility, economic viability, and acceptable regulatory risk. Here, we present the status of this effort and a framework for understanding the challenges and opportunities that will guide introduction of smart shunts into patient care.

  13. Successful Embolization of a Spontaneous Mesocaval Shunt Using the Amplatzer Vascular Plug II

    International Nuclear Information System (INIS)

    Boixadera, Helena; Tomasello, Alejandro; Quiroga, Sergi; Cordoba, Joan; Perez, Mercedes; Segarra, Antoni

    2010-01-01

    A 48-year-old man with alcoholic liver cirrhosis and hepatic encephalopathy was found to have a large, spontaneous mesocaval shunt. The shunt was successfully occluded with the use of an Amplatzer Vascular Plug. To our knowledge, this is the first report of the use of this device to embolize a mesocaval shunt involving the superior mesenteric vein.

  14. Posthemorrhagic Hydrocephalus in Newborns: Clinical Characteristics and Role of Ventriculoperitoneal Shunts

    Directory of Open Access Journals (Sweden)

    Inn-Chi Lee

    2009-02-01

    Conclusion: Patients who were shunt-dependent had worse neurodevelopmental outcomes and greater mortality than those without shunts. The results appeared to depend on how far the hydrocephalus had progressed and on the degree of IVH, but the necessity of VP shunts requires reevaluation before they are implanted.

  15. Shoulder tip pain: an under-reported complication of ventriculoperitoneal shunt.

    LENUS (Irish Health Repository)

    Lim, C

    2012-02-03

    Ventriculoperitoneal (VP) shunt insertion is the commonest form of treatment for hydrocephalus. Shoulder tip pain after VP shunt insertion is unusual and has only recently been reported. We present a case of excruciating shoulder tip pain due to diaphragmatic irritation after VP shunt insertion.

  16. Treatment of Occluded Distal Splenorenal Shunts with Endovascular Stents: A Report of Two Cases

    International Nuclear Information System (INIS)

    Lopez-Medina, Antonio; Peiro, Javier; Gonzalez de Garay, Miguel; Antonana, Miguel A.; Sustacha, Jon; Grande, Domingo

    2001-01-01

    Surgical treatment of an occluded or stenotic portosystemic shunt is difficult and carries a high risk of mortality. We report two cases of early thrombosis of distal splenorenal shunt (DSRS) successfully treated by transcatheter recanalization and stent placement. At 18-month follow-up, the patients remained asymptomatic and control venograms showed continued patency of the shunt with no evidence of stenosis or collaterals

  17. Silent and Efficient Supersonic Bi-Directional Flying Wing

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a Phase I study for a novel concept of a supersonic bi-directional (SBiDir) flying wing (FW) that has the potential to revolutionize supersonic flight...

  18. Effect of particle nonsphericity on bidirectional reflectance of cirrus clouds

    Energy Technology Data Exchange (ETDEWEB)

    Mishchenko, M.I.; Rossow, W.B.; Macke, A.; Lacis, A.A. [Goddard Institute for Space Studies, New York, NY (United States)

    1996-04-01

    This paper describes the use of the fractal ice particle method to study the differences in bidirectional reflectance caused by the differences in the single scattering phase functions of spherical water droplets and nonspherical ice crystals.

  19. Bidirectional Prospective Associations between Cardiac Autonomic Activity and Inflammatory Markers

    NARCIS (Netherlands)

    Hu, Mandy X; Lamers, Femke; Neijts, Melanie; Willemsen, Gonneke; de Geus, Eco J C; Penninx, Brenda W J H

    2018-01-01

    OBJECTIVE: Autonomic nervous system (ANS) imbalance has been cross-sectionally associated with inflammatory processes. Longitudinal studies are needed to shed light on the nature of this relationship. We examined cross-sectional and bidirectional prospective associations between cardiac autonomic

  20. Compiling a Bidirectional Dictionary Bridging English and the Sotho ...

    African Journals Online (AJOL)

    rbr

    bi-directional Sesotho sa Leboa ↔ Sesotho, Sesotho sa Leboa ↔ Setswana and ... example, the 100 most frequently used words in Sesotho sa Leboa in ranking .... Consider in this regard a selection of such mutual lexical items with high.

  1. Encoding Strategy for Maximum Noise Tolerance Bidirectional Associative Memory

    National Research Council Canada - National Science Library

    Shen, Dan

    2003-01-01

    In this paper, the Basic Bidirectional Associative Memory (BAM) is extended by choosing weights in the correlation matrix, for a given set of training pairs, which result in a maximum noise tolerance set for BAM...

  2. High-Flow Arterio-Hepatic Venous Shunt in Hepatocellular Carcinoma: Use of Multi-Electrode Radiofrequency for Shunt Obliteration

    Energy Technology Data Exchange (ETDEWEB)

    Pua, Uei, E-mail: druei@yahoo.com [Tan Tock Seng Hospital, Department of Diagnostic Radiology (Singapore)

    2015-10-15

    Intra-tumoral arterio-hepatic venous shunting (AHVS) poses an impediment to transarterial chemoembolization of liver tumors. Not only does it present a potential hazard for systemic shunting and embolization, but also the altered flow dynamics may also result in poor delivery of drug/embolics to the target tumor bed. Current available techniques to overcome AVHS include arterial embolization (particles, coils, glue, etc.) or temporary venous occlusion using balloons. We hereby illustrate the use of radiofrequency ablation to obliterate a complex AHVS consisting of a varix-like venous aneurysm.

  3. Featurized Bidirectional GAN: Adversarial Defense via Adversarially Learned Semantic Inference

    OpenAIRE

    Bao, Ruying; Liang, Sihang; Wang, Qingcan

    2018-01-01

    Deep neural networks have been demonstrated to be vulnerable to adversarial attacks, where small perturbations are intentionally added to the original inputs to fool the classifier. In this paper, we propose a defense method, Featurized Bidirectional Generative Adversarial Networks (FBGAN), to capture the semantic features of the input and filter the non-semantic perturbation. FBGAN is pre-trained on the clean dataset in an unsupervised manner, adversarially learning a bidirectional mapping b...

  4. Bidirectional uncompressed HD video distribution over fiber employing VCSELs

    DEFF Research Database (Denmark)

    Estaran Tolosa, Jose Manuel; Vegas Olmos, Juan José; Rodes, G. A.

    2012-01-01

    We report on a bidirectional system in which VCSELs are simultaneously modulated with two uncompressed HD video signals. The results show a large power budget and a negligible penalty over 10 km long transmission links.......We report on a bidirectional system in which VCSELs are simultaneously modulated with two uncompressed HD video signals. The results show a large power budget and a negligible penalty over 10 km long transmission links....

  5. ABOUT HYBRID BIDIRECTIONAL ASSOCIATIVE MEMORY NEURAL NETWORKS WITH DISCRETE DELAYS

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper, hybrid bidirectional associative memory neural networks with discrete delays is considered. By ingeniously importing real parameters di > 0(i = 1,2,···,n) which can be adjusted, we establish some new sufficient conditions for the dynamical characteristics of hybrid bidirectional associative memory neural networks with discrete delays by the method of variation of parameters and some analysis techniques. Our results generalize and improve the related results in [10,11]. Our work is significant...

  6. Risk factors for shunt malfunction in pediatric hydrocephalus: a multicenter prospective cohort study.

    Science.gov (United States)

    Riva-Cambrin, Jay; Kestle, John R W; Holubkov, Richard; Butler, Jerry; Kulkarni, Abhaya V; Drake, James; Whitehead, William E; Wellons, John C; Shannon, Chevis N; Tamber, Mandeep S; Limbrick, David D; Rozzelle, Curtis; Browd, Samuel R; Simon, Tamara D

    2016-04-01

    OBJECT The rate of CSF shunt failure remains unacceptably high. The Hydrocephalus Clinical Research Network (HCRN) conducted a comprehensive prospective observational study of hydrocephalus management, the aim of which was to isolate specific risk factors for shunt failure. METHODS The study followed all first-time shunt insertions in children younger than 19 years at 6 HCRN centers. The HCRN Investigator Committee selected, a priori, 21 variables to be examined, including clinical, radiographic, and shunt design variables. Shunt failure was defined as shunt revision, subsequent endoscopic third ventriculostomy, or shunt infection. Important a priori-defined risk factors as well as those significant in univariate analyses were then tested for independence using multivariate Cox proportional hazard modeling. RESULTS A total of 1036 children underwent initial CSF shunt placement between April 2008 and December 2011. Of these, 344 patients experienced shunt failure, including 265 malfunctions and 79 infections. The mean and median length of follow-up for the entire cohort was 400 days and 264 days, respectively. The Cox model found that age younger than 6 months at first shunt placement (HR 1.6 [95% CI 1.1-2.1]), a cardiac comorbidity (HR 1.4 [95% CI 1.0-2.1]), and endoscopic placement (HR 1.9 [95% CI 1.2-2.9]) were independently associated with reduced shunt survival. The following had no independent associations with shunt survival: etiology, payer, center, valve design, valve programmability, the use of ultrasound or stereotactic guidance, and surgeon experience and volume. CONCLUSIONS This is the largest prospective study reported on children with CSF shunts for hydrocephalus. It confirms that a young age and the use of the endoscope are risk factors for first shunt failure and that valve type has no impact. A new risk factor-an existing cardiac comorbidity-was also associated with shunt failure.

  7. Assessment of surgical portosystemic shunts and associated complications: The diagnostic and therapeutic role of radiologists

    Energy Technology Data Exchange (ETDEWEB)

    Taslakian, Bedros, E-mail: btaslakian@gmail.com [Department of Radiology, American University of Beirut Medical Center, Riad El-Solh 1107 2020—PO Box: 11-0236, Beirut (Lebanon); Faraj, Walid, E-mail: wf07@aub.edu.lb [Department of General Surgery, American University of Beirut Medical Center, Riad El-Solh 1107 2020—PO Box: 11-0236, Beirut (Lebanon); Khalife, Mohammad, E-mail: mk12@aub.edu.lb [Department of General Surgery, American University of Beirut Medical Center, Riad El-Solh 1107 2020—PO Box: 11-0236, Beirut (Lebanon); Al-Kutoubi, Aghiad, E-mail: mk00@aub.edu.lb [Department of Radiology, American University of Beirut Medical Center, Riad El-Solh 1107 2020—PO Box: 11-0236, Beirut (Lebanon); El-Merhi, Fadi, E-mail: fe19@aub.edu.lb [Department of Radiology, American University of Beirut Medical Center, Riad El-Solh 1107 2020—PO Box: 11-0236, Beirut (Lebanon); Saade, Charbel, E-mail: cs39@aub.edu.lb [Department of Radiology, American University of Beirut Medical Center, Riad El-Solh 1107 2020—PO Box: 11-0236, Beirut (Lebanon); Hallal, Ali, E-mail: ah05@aub.edu.lb [Department of General Surgery, American University of Beirut Medical Center, Riad El-Solh 1107 2020—PO Box: 11-0236, Beirut (Lebanon); Haydar, Ali, E-mail: ah24@aub.edu.lb [Department of Radiology, American University of Beirut Medical Center, Riad El-Solh 1107 2020—PO Box: 11-0236, Beirut (Lebanon)

    2015-08-15

    Highlights: • Portal hypertension is the pathological increase in portal venous pressure. • Surgical portosystemic shunting is an accepted methods to decrease portal venous pressure. • Surgical portosystemic shunts are divided into selective and nonselective. • Shunt thrombosis is a serious complication, resulting in shunt dysfunction. • Imaging is essential in the assessment of the shunt function and anatomy. - Abstract: Surgical portosystemic shunting, the formation of a vascular connection between the portal and systemic venous circulation, has been used as a treatment to reduce portal venous pressure. Although the use of portosystemic shunt surgery in the management of portal hypertension has declined during the past decade in favour of alternative therapies, and subsequently surgeons and radiologists became less familiar with the procedure, it remains a well-established treatment. Knowledge of different types of surgical portosystemic shunts, their pathophysiology and complications will help radiologists improve communication with surgeons and enhance their understanding of the diagnostic and therapeutic role of radiology in the assessment and management of these shunts. Optimal assessment of the shunt is essential to determine its patency and allow timely intervention. Both non-invasive and invasive imaging modalities complement each other in the evaluation of surgical portosystemic shunts. Interventional radiology plays an important role in the management of complications, such as shunt thrombosis and stenosis. This article describes the various types of surgical portosystemic shunts, explains the anatomy and pathophysiology of these shunts, illustrates the pearls and pitfalls of different imaging modalities in the assessment of these shunts and demonstrates the role of radiologists in the interventional management of complications.

  8. Assessment of surgical portosystemic shunts and associated complications: The diagnostic and therapeutic role of radiologists

    International Nuclear Information System (INIS)

    Taslakian, Bedros; Faraj, Walid; Khalife, Mohammad; Al-Kutoubi, Aghiad; El-Merhi, Fadi; Saade, Charbel; Hallal, Ali; Haydar, Ali

    2015-01-01

    Highlights: • Portal hypertension is the pathological increase in portal venous pressure. • Surgical portosystemic shunting is an accepted methods to decrease portal venous pressure. • Surgical portosystemic shunts are divided into selective and nonselective. • Shunt thrombosis is a serious complication, resulting in shunt dysfunction. • Imaging is essential in the assessment of the shunt function and anatomy. - Abstract: Surgical portosystemic shunting, the formation of a vascular connection between the portal and systemic venous circulation, has been used as a treatment to reduce portal venous pressure. Although the use of portosystemic shunt surgery in the management of portal hypertension has declined during the past decade in favour of alternative therapies, and subsequently surgeons and radiologists became less familiar with the procedure, it remains a well-established treatment. Knowledge of different types of surgical portosystemic shunts, their pathophysiology and complications will help radiologists improve communication with surgeons and enhance their understanding of the diagnostic and therapeutic role of radiology in the assessment and management of these shunts. Optimal assessment of the shunt is essential to determine its patency and allow timely intervention. Both non-invasive and invasive imaging modalities complement each other in the evaluation of surgical portosystemic shunts. Interventional radiology plays an important role in the management of complications, such as shunt thrombosis and stenosis. This article describes the various types of surgical portosystemic shunts, explains the anatomy and pathophysiology of these shunts, illustrates the pearls and pitfalls of different imaging modalities in the assessment of these shunts and demonstrates the role of radiologists in the interventional management of complications

  9. Bidirectional associations between emotions and school adjustment.

    Science.gov (United States)

    Hernández, Maciel M; Eisenberg, Nancy; Valiente, Carlos; Spinrad, Tracy L; Berger, Rebecca H; VanSchyndel, Sarah K; Silva, Kassondra M; Diaz, Anjolii; Thompson, Marilyn S; Gal, Diana E; Southworth, Jody

    2017-11-24

    We examined the relations of children's (N = 301) observed expression of negative and positive emotion in classes or nonclassroom school contexts (i.e., lunch and recess) to school adjustment from kindergarten to first grade. Naturalistic observations of children's emotional expressivity were collected, as were teachers' reports of children's school engagement and relationship quality with teachers and peers. In longitudinal panel models, greater teacher-student conflict and lower student engagement in kindergarten predicted greater negative expressivity in both school contexts. School engagement and peer acceptance in kindergarten positively predicted first grade positive emotion in the classroom. Suggestive of possible bidirectional relations, there was also small unique prediction (near significant) from negative expressivity at lunch and recess to higher teacher-student conflict, from negative expressivity in the classroom to low peer acceptance, and from positive expressivity in the classroom to higher peer acceptance. The pattern of findings suggests that the quality of experience at school uniquely predicts children's emotional expressivity at school more consistently than vice versa-a finding that highlights the important role of school context in young children's emotionality at school. © 2017 Wiley Periodicals, Inc.

  10. Single coil bistable, bidirectional micromechanical actuator

    Science.gov (United States)

    Tabat, Ned; Guckel, Henry

    1998-09-15

    Micromechanical actuators capable of bidirectional and bistable operation can be formed on substrates using lithographic processing techniques. Bistable operation of the microactuator is obtained using a single coil and a magnetic core with a gap. A plunger having two magnetic heads is supported for back and forth linear movement with respect to the gap in the magnetic core, and is spring biased to a neutral position in which the two heads are on each side of the gap in the core. The single electrical coil is coupled to the core and is provided with electrical current to attract one of the heads toward the core by reluctance action to drive the plunger to a limit of travel in one direction. The current is then cut off and the plunger returns by spring action toward the gap, whereafter the current is reapplied to the coil to attract the other head of the plunger by reluctance action to drive the plunger to its other limit of travel. This process can be repeated at a time when switching of the actuator is required.

  11. Electromigration failures under bidirectional current stress

    Science.gov (United States)

    Tao, Jiang; Cheung, Nathan W.; Hu, Chenming

    1998-01-01

    Electromigration failure under DC stress has been studied for more than 30 years, and the methodologies for accelerated DC testing and design rules have been well established in the IC industry. However, the electromigration behavior and design rules under time-varying current stress are still unclear. In CMOS circuits, as many interconnects carry pulsed-DC (local VCC and VSS lines) and bidirectional AC current (clock and signal lines), it is essential to assess the reliability of metallization systems under these conditions. Failure mechanisms of different metallization systems (Al-Si, Al-Cu, Cu, TiN/Al-alloy/TiN, etc.) and different metallization structures (via, plug and interconnect) under AC current stress in a wide frequency range (from mHz to 500 MHz) has been study in this paper. Based on these experimental results, a damage healing model is developed, and electromigration design rules are proposed. It shows that in the circuit operating frequency range, the "design-rule current" is the time-average current. The pure AC component of the current only contributes to self-heating, while the average (DC component) current contributes to electromigration. To ensure longer thermal-migration lifetime under high frequency AC stress, an additional design rule is proposed to limit the temperature rise due to self-joule heating.

  12. Passive Resonant Bidirectional Converter with Galvanic Barrier

    Science.gov (United States)

    Rosenblad, Nathan S. (Inventor)

    2014-01-01

    A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

  13. Shunt hybrid active power filter for harmonic mitigation: A practical ...

    Indian Academy of Sciences (India)

    shunt HAPF, APF is connected in series with PPF and the whole system is connected in parallel to the load. ... LC filter, it will force a fundamental reactive current to flow into it. ..... Since SHAPF is operating as a boost rectifier, d.c. voltage.

  14. Leakage Inductance Calculation for Planar Transformers with a Magnetic Shunt

    DEFF Research Database (Denmark)

    Jun, Zhang; Ouyang, Ziwei; Duffy, M. C.

    2013-01-01

    The magnetic shunt is generally inserted in a planar transformer to increase the leakage inductance which can be utilized as the series inductor in resonant circuits such as the LLC resonant converter. This paper presents a calculation methodology for the leakage inductance of the transformer...

  15. A plasma polymerization technique to overcome cerebrospinal fluid shunt infections

    Czech Academy of Sciences Publication Activity Database

    Çökeliler, D.; Caner, H.; Zemek, Josef; Choukourov, A.; Biederman, H.; Mutlu, M.

    2007-01-01

    Roč. 2, č. 1 (2007), s. 39-47 ISSN 1748-6041 Grant - others:TUBITAK(TR) MISAG-COST 527 Institutional research plan: CEZ:AV0Z10100521 Keywords : shunt infections * cerebrospinal * PP HEMA * biomaterials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.787, year: 2007

  16. Systemic Arterial-to-Pulmonary Artery Shunt Utilization

    African Journals Online (AJOL)

    multiruka1

    In certain circumstances, such as cyanotic neonates with tetralogy of Fallot (4) or cyanotic patients with. Tetralogy of Fallot and hypoplastic pulmonary arteries. (5), better outcomes are obtained if definitive surgery. (total correction or palliation) is preceded by creation of a systemic arterial-to-pulmonary artery shunt (SAPAS).

  17. Shunt hybrid active power filter for harmonic mitigation: A practical ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... The increasing importance of Power Quality problems has been responsible for several improvements in Active Power Filter (APF) typologies in the last decade. The increased cost and switching losses make a pure shunt APF economically impractical for high power applications. In higher power levels ...

  18. k-Shortest routing of trains on shunting yards

    NARCIS (Netherlands)

    Riezebos, Jan; van Wezel, Wout

    2009-01-01

    We consider the problem of designing algorithmic support for k-best routing decisions in train shunting scheduling. A study at the Netherlands Railways revealed that planners like to interact with the solution process of finding suitable routes. Two types of interaction were required: the

  19. Aberrant hepatic lipid storage and metabolism in canine portosystemic shunts

    NARCIS (Netherlands)

    Van Den Bossche, Lindsay; Schoonenberg, Vivien A.C.; Burgener, Iwan A.; Penning, Louis C.; Schrall, Ingrid M.; Kruitwagen, Hedwig S.; Van Wolferen, Monique E.; Grinwis, Guy C.M.; Kummeling, Anne; Rothuizen, Jan; Van Velzen, Jeroen F.; Stathonikos, Nikolas; Molenaar, Martijn R.; Helms, Bernd J.; Brouwers, Jos F.H.M.; Spee, Bart; Van Steenbeek, Frank G.

    2017-01-01

    Non-alcoholic fatty liver disease (NAFLD) is a poorly understood multifactorial pandemic disorder. One of the hallmarks of NAFLD, hepatic steatosis, is a common feature in canine congenital portosystemic shunts. The aim of this study was to gain detailed insight into the pathogenesis of steatosis in

  20. Anatomical Evidence for Intracardiac Blood Shunting in Marine Turtles

    African Journals Online (AJOL)

    ... suggests that right to left intra-cardiac blood shunts may be a feature of diving in sea turtles; the sphincter providing a mechanism for the control of blood flow through the heart. The comparative anatomy of the pulmonary arteries of selected terrestrial reptiles suggests that a similar mechanism exists in non-diving species.

  1. Reversible Venting Stitch for Fenestrating Valve-less Glaucoma Shunts.

    Science.gov (United States)

    Akil, Handan; Vu, Priscilla Q; Nguyen, Anhtuan H; Nugent, Alexander; Chopra, Vikas; Francis, Brian A; Tan, James C

    2017-12-01

    The purpose of this is to describe a venting stitch modification for valveless glaucoma aqueous shunts and characterize early postoperative intraocular pressure (IOP) and glaucoma medication use following the modification. Retrospective chart review of 61 sequential patients undergoing Baerveldt glaucoma implant (BGI)-350 implantation at the Doheny Eye Institute. Twenty-four patients received a glaucoma shunt with venting stitch modification (modified BGI) and 37 patients received an unmodified shunt (BGI-only). IOP, number of glaucoma medications, and number of hypotony cases (intraocular pressure ≤5 mm Hg) were compared between the groups. T-tests were used for statistical analysis. At postoperative-day 1, mean IOP was significantly lower compared with preoperatively in the modified BGI group (14 mm Hg; reduced by 51%; P<0.0001) but not the BGI-only group (27 mm Hg; P=0.06). IOP difference between groups persisted till immediately before tube opening (P=0.005) and fewer IOP-lowering medications needed in the modified BGI group (P<0.0001). One case (4.2%) of postoperative hypotony was encountered with BGI modification, which resolved after the stitch was removed in clinic. The venting stitch valveless shunt modification allows for effective, reliable, and safe control of early postoperative IOP.

  2. Small-Diameter PTFE Portosystemic Shunts: Portocaval vs Mesocaval

    Directory of Open Access Journals (Sweden)

    Robert Shields

    1998-01-01

    Full Text Available Fifty-seven patients with failed sclerotherapy received a mesocaval interposition shunt with an externally supported, ringed polytetrafluoroethylene prosthesis of either 10 or 12 mm diameter. Thirty-one patients had Child-Pugh gradeA disease and 26 grade B; all had a liver volume of 1000– 2500 ml. Follow-up ranged from 16 months to 6 years 3 months. Three patients (5 per cent died in the postoperative period. There were two postoperative recurrences of variceal haemorrhage and one recurrent bleed in the second year after surgery. The cumulative shunt patency rate was 95 per cent and the incidence of encephalopathy 9 per cent; the latter was successfully managed by protein restriction and/or lactulose therapy. The actuarial survival rate for the whole group at 6 years was 78 per cent, for those with Child-Pugh grade A 88 per cent and for grade B 67 per cent. Small-lumen mesocaval interposition shunting achieves portal decompression, preserves hepatopetal flow, has a low incidence of shunt thrombosis, prevents recurrent variceal bleeding and is not associated with significant postoperative encephalopathy.

  3. Shunt impedance measurement of the APS BBC injector

    International Nuclear Information System (INIS)

    Sun, Y.E.; Lewellen, J.W.

    2006-01-01

    The injector test stand (ITS) at Advanced Photon Source (APS) presently incorporates a ballistic bunch compression (BBC) gun, and it is used as a beam source for a number of experiments, including THz generation, beam position monitor testing for the Linac Coherent Light Source (LCLS), novel cathode testing, and radiation therapy source development. The BBC gun uses three independently powered and phased rf cavities, one cathode cell, and two full cells to provide beam energies from 2 to 10 MeV with variable energy spread, energy chirp, and, to an extent, bunch duration. The shunt impedance of an rf accelerator determines how effectively the accelerator can convert supplied rf power to accelerating gradient. The calculation of the shunt impedance can be complicated if the beam energy changes substantially during its transit through a cavity, such as in a cathode cell. We present the results of direct measurements of the shunt impedance of the APS BBC gun on an individual cavity basis, including the cathode cell, and report on achieved gradients. We also present a comparison of the measured shunt impedance with theoretical values calculated from the rf models of the cavities.

  4. Temporary vascular shunting in vascular trauma: A 10-year review ...

    African Journals Online (AJOL)

    of a physiologically unstable patient requiring a damage control procedure, and in the ... ensure that the tubing would not fall out, but not so tight that the lumen of the .... Time to removal of the shunt represents a balance between removing the ...

  5. Congenital extrahepatic portosystemic shunt associated with heterotaxy and polysplenia

    Energy Technology Data Exchange (ETDEWEB)

    Newman, Beverley [Lucile Packard Children' s Hospital, Department of Radiology, Stanford University School of Medicine, Stanford, CA (United States); Feinstein, Jeffrey A. [Stanford University School of Medicine, Division of Pediatric Cardiology, Department of Pediatrics, Lucile Packard Children' s Hospital, Stanford (United States); Cohen, Ronald A.; Patel, Hitendra [Children' s Hospital and Research Center, Department of Diagnostic Radiology, Oakland, CA (United States); Feingold, Brian; Kreutzer, Jacqueline [Children' s Hospital of Pittsburgh, Department of Pediatrics, Division of Pediatric Cardiology, Pittsburgh, PA (United States); Chan, Fandics P. [Stanford University School of Medicine, Cardiovascular Imaging Section, Department of Radiology, Lucile Packard Children' s Hospital, Stanford, CA (United States)

    2010-07-15

    Heterotaxy with polysplenia is associated with many cardiovascular anomalies including the occasional occurrence of congenital extrahepatic portosystemic shunts (CEPS). Missing this anomaly can lead to inappropriate and ineffective therapy. To emphasize the importance and associated anatomy of CEPS in conjunction with heterotaxy with polysplenia. Review of three young children who presented with cyanosis and pulmonary hypertension without a cardiac etiology. They were known (1) or discovered (2) to have heterotaxy with polysplenia. There was absence of the intrahepatic inferior vena cava (IVC) with azygos or hemiazygos continuation in all three cases. In spite of normal liver function, they were discovered to have large portosystemic shunts, splenorenal in location, along with diffuse peripheral pulmonary arterial dilatation suggestive of CEPS (Abernethy malformation) with hepatopulmonary or, more accurately, portopulmonary syndrome. All CEPS were ipsilateral to the spleens. Patency of the portal veins in these cases allowed for percutaneous shunt closure with resolution of cyanosis. CEPS is associated with heterotaxy with polysplenia and can be symptomatic because of pulmonary arteriovenous (AV) shunting. Portal and hepatic vein patency are critical for determining feasibility of CEPS closure. (orig.)

  6. Effects of an interatrial shunt on rest and exercise hemodynamics

    DEFF Research Database (Denmark)

    Kaye, David; Shah, Sanjiv J; Borlaug, Barry A

    2014-01-01

    BACKGROUND: A treatment based on an interatrial shunt device has been proposed for counteracting elevated pulmonary capillary wedge pressure (PCWP) in patients with heart failure and mildly reduced or preserved ejection fraction (HFpEF). We tested the theoretical hemodynamic effects of this appro...

  7. Creating interatrial shunts in heart failure and pulmonary hypertension

    DEFF Research Database (Denmark)

    Wolsk, Emil; Gustafsson, Finn

    2016-01-01

    Patients with elevated filling pressures are at increased risk of adverse cardiovascular (CV) outcomes. Structural interventions to lower elevated either left or right atrial filling pressures are gaining attention. Studies in heart failure show that lowering left atrial pressure may reduce CV...... interatrial device shunt therapy a part of our armamentarium in patients with heart failure or pulmonary hypertension and increased filling pressure....

  8. Embolization of nonvariceal portosystemic collaterals in transjugular intrahepatic portosystemic shunts

    International Nuclear Information System (INIS)

    Bilbao, Jose Ignacio; Arias, Mercedes; Longo, Jesus Maria; Alejandre, Pedro Luis; Betes, Maria Teresa; Elizalde, Arlette Maria

    1997-01-01

    Percutaneous embolization of large portosystemic collaterals was performed in three patients following placement of a transjugular intrahepatic portosystemic shunt in order to improve hepatopetal portal flow. Improved hepatic portal perfusion was achieved in these cases, thereby theoretically reducing the risk of chronic hepatic encephalopathy

  9. Global robust stability for shunting inhibitory CNNs with delays.

    Science.gov (United States)

    Wang, Lingna; Lin, Yiping

    2004-08-01

    In this paper, the problem of global robust stability for shunting inhibitory cellular neural networks (SICNNs) is studied. A sufficient condition guaranteeing the network's global robust stability is established. The result can easily be used to verify globally robust stable networks. An example is given to illustrate that the conditions of our results are feasible.

  10. A new method for the measurement of intrahepatic shunts

    International Nuclear Information System (INIS)

    Hoefs, J.C.; Reynolds, T.B.; Pare, P.; Sakimura, I.

    1984-01-01

    After transhepatic portal pressure determination, 96 patients were assessed for the presence of intrahepatic shunts by injection of microspheres (25 +/- 5 micron diameter) into the portal vein using RISA-131I as an indicator of dilution. Multiple portal vein injections in each patient allowed blood sampling from the hepatic vein (site 1) and from two inferior vena cava sampling sites (site 2, at the junction of the hepatic vein orifice with the inferior vena cava, and site 3, 2 to 3 cm closer to or within the right atrium). Intrahepatic shunting was calculated from each site: hepatic vein in 57 patients and inferior vena cava, site 2 in 43 patients and site 3 in 77 patients. At least one valid IHS calculation was available in 92 of the patients. Intrahepatic shunting calculated from sequential portal vein injections with sampling from the hepatic vein was highly correlated (r . 0.98, p less than 0.0001, slope . 1.0), with a mean difference of 1.9% +/- 1.9%. There was no significant difference by t test comparison of the mean IHS calculated from sites 1, 2, and 3. Occasional marked discrepancies were noted between IHS calculated from site 1 or site 2 compared with site 3, and the site 3 calculation was always greater. A shunt index in all patients included shunts calculated from the hepatic vein in 57 patients plus shunt calculation from the inferior vena cava in the remaining patients (site 2 in 26 patients and site 3 in nine). The 82 patients with portal hypertension or chronic liver disease had a higher portal pressure, 13.8 +/- 4.6 mm Hg, and a significantly greater shunt index, 13.7% +/- 24.5% compared with controls. The frequency distribution of IHS in patients with chronic liver disease demonstrated less than 2% IHS in 49% of patients and less than 5% IHS in 63%. The validity of our methods and the implications of the infrequent demonstration of a large IHS are discussed

  11. New and improved ways to treat hydrocephalus: Pursuit of a smart shunt

    Science.gov (United States)

    Lutz, Barry R.; Venkataraman, Pranav; Browd, Samuel R.

    2013-01-01

    The most common treatment for hydrocephalus is placement of a cerebrospinal fluid shunt to supplement or replace lost drainage capacity. Shunts are life-saving devices but are notorious for high failure rates, difficulty of diagnosing failure, and limited control options. Shunt designs have changed little since their introduction in 1950s, and the few changes introduced have had little to no impact on these long-standing problems. For decades, the community has envisioned a “smart shunt” that could provide advanced control, diagnostics, and communication based on implanted sensors, feedback control, and telemetry. The most emphasized contribution of smart shunts is the potential for advanced control algorithms, such as weaning from shunt dependency and personalized control. With sensor-based control comes the opportunity to provide data to the physician on patient condition and shunt function, perhaps even by a smart phone. An often ignored but highly valuable contribution would be designs that correct the high failure rates of existing shunts. Despite the long history and increasing development activity in the past decade, patients are yet to see a commercialized smart shunt. Most smart shunt development focuses on concepts or on isolated technical features, but successful smart shunt designs will be a balance between technical feasibility, economic viability, and acceptable regulatory risk. Here, we present the status of this effort and a framework for understanding the challenges and opportunities that will guide introduction of smart shunts into patient care. PMID:23653889

  12. Uterine perforation by a cystoperitoneal shunt, an unusual cause of recurrent vaginal discharge.

    Science.gov (United States)

    Poilblanc, Mathieu; Sentilhes, Loïc; Mercier, Philippe; Lefèbvre, Céline; Descamps, Philippe

    2012-01-01

    We describe the first reported case of uterine perforation by a cystoperitoneal shunt. The mechanism of this unusual complication is unclear. A 17-year-old patient had a cystoperitoneal shunt for a porencephalic cyst. She presented with recurrent watery vaginal discharge. A pelvic ultrasound examination showed that the uterus had been perforated by the distal tip of the shunt. The cystoperitoneal shunt was converted to a ventriculo-atrial shunt, and the vaginal discharge subsequently resolved. The appearance of light and clear vaginal discharge in a patient with a cystoperitoneal shunt raises the possibility of uterine perforation. This can be confirmed by ultrasound and analysis of the discharge. Removal of the shunt leads to spontaneous closure of the uterine defect.

  13. Bacterial contamination of surgeons' gloves during shunt insertion; a pilot study

    DEFF Research Database (Denmark)

    Sørensen, Preben; Ejlertsen, Tove; Aaen, Dorte

    2008-01-01

    Bacterial infection is a major cause of shunt dysfunction. It is well-known that the majority of pathogenic micro-organisms are low-virulent bacteria normally found on intact skin. Probably shunts become contaminated during surgery either by contact to the patient skin, or contact from contaminated...... gloves or instruments. This study was performed to find out to what extent gloves become contaminated during shunt surgery. Gloves used during shunt implantation were examined in 10 operations. Shunt implantation was done using recommended precautions to avoid infection, including prophylactic...... nurse and assistant were contaminated with micro-organisms less than 15 min after surgery has been commenced and before the shunts were handled. This study offers a feasible, simple and logical explanation of how shunts may become contaminated and infected. A simple measure would be to change the outer...

  14. Experimental Comparison of Piezoelectric and Magnetostrictive Shunt Dampers

    Science.gov (United States)

    Asnani, Vivake M.; Deng, Zhangxian; Scheidler, Justin J.; Dapino, Marcelo J.

    2016-01-01

    A novel mechanism called the vibration ring is being developed to enable energy conversion elements to be incorporated into the driveline of a helicopter or other rotating machines. Unwanted vibration is transduced into electrical energy, which provides a damping effect on the driveline. The generated electrical energy may also be used to power other devices (e.g., health monitoring sensors). PZT (piezoceramic) and PMN-30%PT (single crystal) stacks, as well as a Tb_0.3 Dy_0.7 Fe_1.92 (Terfenol-D) rod with a bias magnet array and a pickup coil, were tested as alternative energy conversion elements to use within the vibration ring. They were tuned for broadband damping using shunt resistors, and dynamic compression testing was conducted in a high-speed load frame. Energy conversion was experimentally optimized at 750Hz by tuning the applied bias stress and resistance values. Dynamic testing was conducted up to 1000Hz to determine the effective compressive modulus, shunt loss factor, internal loss factor, and total loss factor. Some of the trends of modulus and internal loss factor versus frequency were unexplained. The single crystal device exhibited the greatest shunt loss factor whereas the Terfenol-D device had the highest internal and total loss factors. Simulations revealed that internal losses in the Terfenol-D device were elevated by eddy current effects, and an improved magnetic circuit could enhance its shunt damping capabilities. Alternatively, the Terfenol-D device may be simplified to utilize only the eddy current dissipation mechanism (no pickup coil or shunt) to create broadband damping.

  15. Experimental comparison of piezoelectric and magnetostrictive shunt dampers

    Science.gov (United States)

    Asnani, Vivake M.; Deng, Zhangxian; Scheidler, Justin J.; Dapino, Marcelo J.

    2016-04-01

    A novel mechanism called the vibration ring is being developed to enable energy conversion elements to be incorporated into the driveline of a helicopter or other rotating machines. Unwanted vibration is transduced into electrical energy, which provides a damping effect on the driveline. The generated electrical energy may also be used to power other devices (e.g., health monitoring sensors). PZT (`piezoceramic') and PMN-30%PT (`single crystal') stacks, as well as a Tb0.3Dy0.7Fe1.92 (`Terfenol-D') rod with a bias magnet array and a pickup coil, were tested as alternative energy conversion elements to use within the vibration ring. They were tuned for broadband damping using shunt resistors, and dynamic compression testing was conducted in a high-speed load frame. Energy conversion was experimentally optimized at 750Hz by tuning the applied bias stress and resistance values. Dynamic testing was conducted up to 1000Hz to determine the effective compressive modulus, shunt loss factor, internal loss factor, and total loss factor. Some of the trends of modulus and internal loss factor versus frequency were unexplained. The single crystal device exhibited the greatest shunt loss factor whereas the Terfenol-D device had the highest internal and total loss factors. Simulations revealed that internal losses in the Terfenol-D device were elevated by eddy current effects, and an improved magnetic circuit could enhance its shunt damping capabilities. Alternatively, the Terfenol-D device may be simplified to utilize only the eddy current dissipation mechanism (no pickup coil or shunt) to create broadband damping.

  16. Fuzzy Inference System Approach for Locating Series, Shunt, and Simultaneous Series-Shunt Faults in Double Circuit Transmission Lines.

    Science.gov (United States)

    Swetapadma, Aleena; Yadav, Anamika

    2015-01-01

    Many schemes are reported for shunt fault location estimation, but fault location estimation of series or open conductor faults has not been dealt with so far. The existing numerical relays only detect the open conductor (series) fault and give the indication of the faulty phase(s), but they are unable to locate the series fault. The repair crew needs to patrol the complete line to find the location of series fault. In this paper fuzzy based fault detection/classification and location schemes in time domain are proposed for both series faults, shunt faults, and simultaneous series and shunt faults. The fault simulation studies and fault location algorithm have been developed using Matlab/Simulink. Synchronized phasors of voltage and current signals of both the ends of the line have been used as input to the proposed fuzzy based fault location scheme. Percentage of error in location of series fault is within 1% and shunt fault is 5% for all the tested fault cases. Validation of percentage of error in location estimation is done using Chi square test with both 1% and 5% level of significance.

  17. An experimental in-vivo canine model for adult shunt infection

    Directory of Open Access Journals (Sweden)

    Procop Gary

    2008-10-01

    Full Text Available Abstract Background Detailed human studies of the mechanisms and development of shunt infection in real time are not possible, and we have developed a canine hydrocephalus model to overcome this. The intention of this pilot study was to show that the canine hydrocephalus model could be shunted using conventional "human" shunts, and that a shunt infection could be established so that further studies could then be planned. Methods Hydrocephalus was induced in seven dogs (Canis familiaris by fourth ventricle obstruction. Four weeks later they were shunted using a Hakim Precision valve. Four of the dogs received shunts whose ventricular catheter had been inoculated with Staphylococcus epidermidis, and three were uninoculated controls. Four weeks after shunting the dogs were sacrificed and necropsy was performed. Removed shunts and tissue samples were examined microbiologically and isolates were subjected to detailed identification and genomic comparison. Results All the dogs remained well after shunting. Examination of removed shunt components revealed S. epidermidis in the brain and throughout the shunt system in the four inoculated animals, but in two of these Staphylococcus intermedius was also found. S. intermedius was also isolated from all three "negative" controls. There were slight differences between S. intermedius strains suggesting endogenous infection rather than cross- infection from a point source. Conclusion Shunt infection was established in the canine model, and had the experiment been extended beyond four weeks the typical microbiological, pathological and clinical features might have appeared. The occurrence of unplanned shunt infections in control animals due to canine normal skin flora reflects human clinical experience and underlines the usual source of bacteria causing shunt infection.

  18. Predicting ventriculoperitoneal shunt infection in children with hydrocephalus using artificial neural network.

    Science.gov (United States)

    Habibi, Zohreh; Ertiaei, Abolhasan; Nikdad, Mohammad Sadegh; Mirmohseni, Atefeh Sadat; Afarideh, Mohsen; Heidari, Vahid; Saberi, Hooshang; Rezaei, Abdolreza Sheikh; Nejat, Farideh

    2016-11-01

    The relationships between shunt infection and predictive factors have not been previously investigated using Artificial Neural Network (ANN) model. The aim of this study was to develop an ANN model to predict shunt infection in a group of children with shunted hydrocephalus. Among more than 800 ventriculoperitoneal shunt procedures which had been performed between April 2000 and April 2011, 68 patients with shunt infection and 80 controls that fulfilled a set of meticulous inclusion/exclusion criteria were consecutively enrolled. Univariate analysis was performed for a long list of risk factors, and those with p value < 0.2 were used to create ANN and logistic regression (LR) models. Five variables including birth weight, age at the first shunting, shunt revision, prematurity, and myelomeningocele were significantly associated with shunt infection via univariate analysis, and two other variables (intraventricular hemorrhage and coincided infections) had a p value of less than 0.2. Using these seven input variables, ANN and LR models predicted shunt infection with an accuracy of 83.1 % (AUC; 91.98 %, 95 % CI) and 55.7 % (AUC; 76.5, 95 % CI), respectively. The contribution of the factors in the predictive performance of ANN in descending order was history of shunt revision, low birth weight (under 2000 g), history of prematurity, the age at the first shunt procedure, history of intraventricular hemorrhage, history of myelomeningocele, and coinfection. The findings show that artificial neural networks can predict shunt infection with a high level of accuracy in children with shunted hydrocephalus. Also, the contribution of different risk factors in the prediction of shunt infection can be determined using the trained network.

  19. Bidirectional Frontoparietal Oscillatory Systems Support Working Memory.

    Science.gov (United States)

    Johnson, Elizabeth L; Dewar, Callum D; Solbakk, Anne-Kristin; Endestad, Tor; Meling, Torstein R; Knight, Robert T

    2017-06-19

    The ability to represent and select information in working memory provides the neurobiological infrastructure for human cognition. For 80 years, dominant views of working memory have focused on the key role of prefrontal cortex (PFC) [1-8]. However, more recent work has implicated posterior cortical regions [9-12], suggesting that PFC engagement during working memory is dependent on the degree of executive demand. We provide evidence from neurological patients with discrete PFC damage that challenges the dominant models attributing working memory to PFC-dependent systems. We show that neural oscillations, which provide a mechanism for PFC to communicate with posterior cortical regions [13], independently subserve communications both to and from PFC-uncovering parallel oscillatory mechanisms for working memory. Fourteen PFC patients and 20 healthy, age-matched controls performed a working memory task where they encoded, maintained, and actively processed information about pairs of common shapes. In controls, the electroencephalogram (EEG) exhibited oscillatory activity in the low-theta range over PFC and directional connectivity from PFC to parieto-occipital regions commensurate with executive processing demands. Concurrent alpha-beta oscillations were observed over parieto-occipital regions, with directional connectivity from parieto-occipital regions to PFC, regardless of processing demands. Accuracy, PFC low-theta activity, and PFC → parieto-occipital connectivity were attenuated in patients, revealing a PFC-independent, alpha-beta system. The PFC patients still demonstrated task proficiency, which indicates that the posterior alpha-beta system provides sufficient resources for working memory. Taken together, our findings reveal neurologically dissociable PFC and parieto-occipital systems and suggest that parallel, bidirectional oscillatory systems form the basis of working memory. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  20. A comparison of micropore membrane inlet mass spectrometry-derived pulmonary shunt measurement with Riley shunt in a porcine model.

    Science.gov (United States)

    Duenges, Bastian; Vogt, Andreas; Bodenstein, Marc; Wang, Hemei; Böhme, Stefan; Röhrig, Bernd; Baumgardner, James E; Markstaller, Klaus

    2009-12-01

    The multiple inert gas elimination technique was developed to measure shunt and the ratio of alveolar ventilation to simultaneous alveolar capillary blood flow in any part of the lung (V(A)'/Q') distributions. Micropore membrane inlet mass spectrometry (MMIMS), instead of gas chromatography, has been introduced for inert gas measurement and shunt determination in a rabbit lung model. However, agreement with a frequently used and accepted method for quantifying deficits in arterial oxygenation has not been established. We compared MMIMS-derived shunt (M-S) as a fraction of total cardiac output (CO) with Riley shunt (R-S) derived from the R-S formula in a porcine lung injury model. To allow a broad variance of atelectasis and therefore shunt fraction, 8 sham animals did not receive lavage, and 8 animals were treated by lung lavages with 30 mL/kg warmed lactated Ringer's solution as follows: 2 animals were lavaged once, 5 animals twice, and 1 animal 3 times. Variables were recorded at baseline and twice after induction of lung injury (T1 and T2). Retention data of sulfur hexafluoride, krypton, desflurane, enflurane, diethyl ether, and acetone were analyzed by MMIMS, and M-S was derived using a known algorithm for the multiple inert gas elimination technique. Standard formulas were used for the calculation of R-S. Forty-four pairs of M-S and R-S were recorded. M-S ranged from 0.1% to 35.4% and R-S from 3.7% to 62.1%. M-S showed a correlation with R-S described by linear regression: M-S = -4.26 + 0.59 x R-S (r(2) = 0.83). M-S was on average lower than R-S (mean = -15.0% CO, sd = 6.5% CO, and median = -15.1), with lower and upper limits of agreement of -28.0% and -2.0%, respectively. The lower and upper limits of the 95% confidence intervals were -17.0 and -13.1 (P < 0.001, Student's t-test). Shunt derived from MMIMS inert gas retention data correlated well with R-S during breathing of oxygen. Shunt as derived by MMIMS was generally less than R-S.

  1. What is the risk of infecting a cerebrospinal fluid-diverting shunt with percutaneous tapping?

    Science.gov (United States)

    Spiegelman, Lindsey; Asija, Richa; Da Silva, Stephanie L; Krieger, Mark D; McComb, J Gordon

    2014-10-01

    Most CSF-diverting shunt systems have an access port that can be percutaneously tapped. Tapping the shunt can yield valuable information as to its function and whether an infection is present. The fear of causing a shunt infection by tapping may limit the physician's willingness to do so. The authors of this study investigate the risk of infecting a shunt secondary to percutaneous tapping. Following institutional review board approval, CSF specimens obtained from tapping an indwelling CSF-diverting shunt during the 2011 and 2012 calendar years were identified and matched with clinical information. A culture-positive CSF sample was defined as an infection. If results were equivocal, such as a broth-only-positive culture, a repeat CSF specimen was examined. The CSF was obtained by tapping the shunt access port with a 25-gauge butterfly needle after prepping the unshaven skin with chlorhexidine. During the study period, 266 children underwent 542 shunt taps. With 541 taps, no clinical evidence of a subsequent shunt infection was found. One child's CSF went from sterile to infected 11 days later; however, this patient had redness along the shunt tract at the time of the initial sterile tap. The risk of infection from tapping a shunt is remote if the procedure is done correctly.

  2. Operação de Glenn bidirecional Bidirectional Glenn anastomosis

    Directory of Open Access Journals (Sweden)

    Paulo Chaccur

    1992-09-01

    Full Text Available A cirurgia de Gleen bidirecional tem sido empregadacomo uma opção ao tratamento cirúrgico de pacientes considerados candidatos "não ideais" à cirurgia de derivação átrio-pulmonar. A operação consiste na anastomose da veia cava superior com a artéria pulmonar (anastomose término-lateral, permitindo o fluxo sanguíneo também para o pulmão contra-lateral. A partir de janeiro de 1990 até fevereiro de 1992, 20 pacientes foram operados em nosso Serviço, com idade variando de 5 meses a 8 anos (média de 37,7 meses. Oito pacientes eram do sexo feminino e o peso variou de 6,3 a 18,8 Kg (média - 12,4 kg. A indicação cirúrgica foi considerada primária em 10 casos. Sete casos de atresia tricúspide e 3 de ventrículo único, que apresentavam acentuada diminuição do fluxo pulmonar e não eram candidatos a correção total funcional. Os demais pacientes tiveram a indicação considerada secundária, ou seja, já haviam sido submetidos a operação de shunt artério-venoso, cerclagem do tranco pulmonar, ou atriosseptostomia, 8 casos de atresia tricúspide, 3 de ventrículo único com estenose ou cerclagem pulmonar e 1 caso de DVSVD com ventrículo superior-inferior. A operação foi realizada com desvio da veia cava-átrio direito em 12 casos e com o uso de CEC em 8. Durante o procedimento cirúrgico, os pacientes foram monitorizados com oxímetro pulsátil e a saturação de oxigênio média pré-correção foi de 75,5% (71% a 86% e após, de 95% (91% a 98%. Não ocorreu óbito hospitalar e o único óbito tardio foi devido a infecção pulmonar no 2º mês de pós-operatório. Achamos, portanto, que a operação de Glenn bidirecional estará bem indicada como primeira etapa da correção definitiva, pois não aumenta o trabalho cardíaco e a resistência vascular pulmonar não produz distorções em artéria pulmonar como shunt tipo Blalock-Taussig.The bidirectional Glenn anastomosis has bee used as an effective mean of palliating

  3. Piezoelectric power converter with bi-directional power transfer

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a bi-directional piezoelectric power converter com¬ prising a piezoelectric transformer. The piezoelectric transformer comprises an input electrode electrically coupled to a primary section of the piezoelectric transformer and an output electrode electrically...... coupled to an output section of the piezoelectric transformer to provide a transformer output signal. A bi-directional switching circuit is coupled between the output electrode and a DC or AC output voltage of the power converter. Forward and reverse current conducting periods of the bi......, a reverse current is conducted through the bi-directional switching circuit from the DC or AC output voltage to the output electrode to discharge the DC or AC output voltage and return power to the primary section of the piezoelectric transformer....

  4. Outpatient blood pressure monitoring using bi-directional text messaging.

    Science.gov (United States)

    Anthony, Chris A; Polgreen, Linnea A; Chounramany, James; Foster, Eric D; Goerdt, Christopher J; Miller, Michelle L; Suneja, Manish; Segre, Alberto M; Carter, Barry L; Polgreen, Philip M

    2015-05-01

    To diagnose hypertension, multiple blood pressure (BP) measurements are recommended. We randomized patients into three groups: EMR-only (patients recorded BP measurements in an electronic medical record [EMR] web portal), EMR + reminders (patients were sent text message reminders to record their BP measurements in the EMR), and bi-directional text messaging (patients were sent a text message asking them to respond with their current BP). Subjects were asked to complete 14 measurements. Automated messages were sent to each patient in the bi-directional text messaging and EMR + reminder groups twice daily. Among 121 patients, those in the bi-directional text messaging group reported the full 14 measurements more often than both the EMR-only group (P text messaging is an effective way to gather patient BP data. Text-message-based reminders alone are an effective way to encourage patients to record BP measurements. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  5. An Adaptive Speed Control Approach for DC Shunt Motors

    Directory of Open Access Journals (Sweden)

    Ruben Tapia-Olvera

    2016-11-01

    Full Text Available A B-spline neural networks-based adaptive control technique for angular speed reference trajectory tracking tasks with highly efficient performance for direct current shunt motors is proposed. A methodology for adaptive control and its proper training procedure are introduced. This algorithm sets the control signal without using a detailed mathematical model nor exact values of the parameters of the nonlinear dynamic system. The proposed robust adaptive tracking control scheme only requires measurements of the velocity output signal. Thus, real-time measurements or estimations of acceleration, current and disturbance signals are avoided. Experimental results confirm the efficient and robust performance of the proposed control approach for highly demanding motor operation conditions exposed to variable-speed reference trajectories and completely unknown load torque. Hence, laboratory experimental tests on a direct current shunt motor prove the viability of the proposed adaptive output feedback trajectory tracking control approach.

  6. US and angiographic examination of brachial dialysis shunts

    International Nuclear Information System (INIS)

    Langer, R.; Langer, M.F.J.; Zwicker, C.; Wakat, J.P.; Treisch, J.

    1988-01-01

    In an experimental study, 13 bypass grafts and eight patches were evaluated. With PTFE-Vitagraft, IMPRA, and Microvel Haemashield grafts total reflection occurred, so that these grafts are not suitable for ultrasound (US) examination. In a prospective clinical trial 40 patients were examined with intraarterial digital subtraction angiography (DSA) and US of the hemodialysis shunts; for DSA, a contrast material with 150 mg/mL of iodine was used. The image quality was excellent in all cases, and no sensation of pain was reported, only a mild sensation of warmth during the injection. The evaluation of image quality for the sonographic investigation showed the following results: shunt artery, 74% excellent, 17% good, and 9% nondiagnostic; anastomosis, 70% excellent, 26% good, and 4% nondiagnostic; draining vein, 91% excellent and 9% good. US is a suitable screening procedure, and DSA can be performed preoperatively without major discomfort and with excellent image quality

  7. Management of intracranial dural arteriovenous shunts in adults

    International Nuclear Information System (INIS)

    Sarma, Dipanka; Brugge, Karel ter

    2003-01-01

    Dural arteriovenous shunts are abnormal arteriovenous communications within the dura. They are thought to be an acquired condition in adults and can present with a variety of clinical features, ranging from benign bruits to intracranial hemorrhage and neurological deficits. The presentation and natural history of these shunts is largely determined by the pattern of venous drainage. Knowledge of natural history and careful study of the angioarchitexture by angiography is therefore mandatory for correct management of these lesions. In this review, principles of management in adults and the various factors that influence treatment decisions are discussed, with a focus on endovascular therapy. Retrograde leptomeningeal or cortical venous drainage has a strong correlation with adverse clinical events and the requirement for aggressive management in this situation is highlighted. Indications for endovascular treatment, therapeutic goals, approaches and techniques are reviewed. The role of surgical treatment is also briefly discussed

  8. Endoscopic third ventriculostomy has no higher costs than ventriculoperitoneal shunt

    Directory of Open Access Journals (Sweden)

    Benicio Oton de Lima

    2014-07-01

    Full Text Available Objective: To evaluate the cost of endoscopic third ventriculostomy (ETV compared to ventriculoperitoneal shunt (VPS in the treatment of hydrocephalus in children. Method: We studied 103 children with hydrocephalus, 52 of which were treated with ETV and 51 with VPS in a prospective cohort. Treatment costs were compared within the first year after surgery, including subsequent surgery or hospitalization. Results: Twenty (38.4% of the 52 children treated with VPS needed another procedure due to shunt failure, compared to 11 (21.5% of 51 children in the ETV group. The average costs per patient in the group treated with ETV was USD$ 2,177,66±517.73 compared to USD$ 2,890.68±2,835.02 for the VPS group. Conclusions: In this series there was no significant difference in costs between the ETV and VPS groups.

  9. GABA shunt in the callus cells derived from soybean cotyledon

    Energy Technology Data Exchange (ETDEWEB)

    Tokunaga, M; Nakano, Y; Kitaoka, S [Osaka Prefectural Univ., Sakai (Japan). Coll. of Agriculture

    1975-01-01

    In the growing callus cells from soybean cotyledon, the activities of glutamate decarboxylase and GABA transaminase were increased in the early phase of the callus growth on the Miller agar medium. Succinate dehydrogenase activity was also changed in a similar manner. From these and the additional evidences that GABA transaminase was probably localized in the mitochondria, it has been made clear that the GABA shunt (GABA by-pass pathway) is operative and contributes to the respiratory metabolism in growing callus cells. Feeding young callus cells with GABA-U-/sup 14/C for 24 hr actually resulted in finding 53% of the taken up radioactivity in released carbon dioxide. Considerable parts of the taken up radioactivity were found in amino acids and proteins which should have been formed via the GABA shunt also.

  10. Anatomy and Classification of Gastrorenal and Gastrocaval Shunts

    Science.gov (United States)

    Sabri, Saher S.; Saad, Wael E. A.

    2011-01-01

    The gastric varices communicate with gastrorenal and gastrocaval shunts and are classified according to the pattern of venous inflow into three types, which differ in the number and location of the inflow veins. The gastric varices are also classified according to their venous drainage into four different types, reflecting the size and number of collateral veins communicating with the gastric varices and the gastrorenal/gastrocaval shunt. Lastly, the gastric varices are classified according to their appearance on balloon-occluded retrograde venography into five grades representing the degree of opacification of the gastric varices and the collateral veins. Understanding these anatomic classifications is crucial in planning endovascular obliteration of gastric varices. PMID:22942547

  11. Analysis and control of a shunt active power filter

    Energy Technology Data Exchange (ETDEWEB)

    Ottersten, R.; Petersson, Andreas [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1999-09-01

    This report deals with active power filtering of low-frequency current harmonics. The active filter consists of a forced-commutated voltage source inverter with a digital control system. The aim of this master thesis is to investigate the performance of a shunt active power filter, and the parameters influence on the system performance. Three different harmonic identification methods are presented and compared. The shunt active power filter is very well suited for harmonic current reduction, provided that the phase shift due to the digital implementation of the control system is compensated. The performance of the active power filter depends on the switching frequency. When using individual harmonic detection methods the amount of compensation can be fully controlled for each current harmonic.

  12. Shunted-Josephson-junction model. I. The autonomous case

    DEFF Research Database (Denmark)

    Belykh, V. N.; Pedersen, Niels Falsig; Sørensen, O. H.

    1977-01-01

    The shunted-Josephson-junction model: the parallel combination of a capacitance, a phase-dependent conductance, and an ideal junction element biased by a constant current, is discussed for arbitrary values of the junction parameters. The main objective is to provide a qualitative understanding...... current-voltage curves are presented. The case with a time-dependent monochromatic bias current is treated in a similar fashion in the companion paper....

  13. Integrating rolling stock scheduling with train unit shunting

    DEFF Research Database (Denmark)

    Haahr, Jørgen Thorlund; Lusby, Richard Martin

    2017-01-01

    In this paper, we consider integrating two important railway optimization problems, in particular the Rolling Stock Scheduling Problem and the Train Unit Shunting Problem. We present two similar branch-and-cut based approaches to solve this integrated problem and, in addition, provide a comparison......, sequential approach ends in infeasibility. Furthermore, for the considered instances, solutions are typically found within a few minutes, indicating the applicability of the methodology to short-term planning....

  14. Pre-Liver Transplant: Tips Versus Distal Splenorenal Shunt

    Directory of Open Access Journals (Sweden)

    Thomas W. Faust

    1997-01-01

    Full Text Available Recurrent variceal bleeding in liver transplant candidates with end-stage liver disease can complicate or even prohibit a subsequent transplant procedure (OLT. Endoscopic sclero-therapy and medical therapy are considered as first-line management with surgical shunts reserved for refractory situations. Surgical shunts can be associated with a high mortality in this population and may complicate subsequent OLT. The transjugular intrahepatic portosystemic shunt (TIPS has been recommended in these patients as a bridge to OLT. This is a new modality that has not been compared with previously established therapies such as the distal splenorenal shunt (DSRS. In this study we report our experience with 35 liver transplant recipients who had a previous TIPS (18 patients or DSRS (17 patients for variceal bleeding. The TIPS group had a significantly larger proportion of critically ill and Child-Pugh C patients. Mean operating time was more prolonged in the DSRS group (P=0.014 but transfusion requirements were similar. Intraoperative portal vein blood flow measurements averaged 2132±725 ml/min in the TIPS group compared with 1120±351ml/min in the DSRS group (P<0.001. Arterial flows were similar. Mean ICU and hospital stays were similar. There were 3 hospital mortalities in the DSRS group and none in the TIPS group (P=0.1. We conclude that TIPS is a valuable tool in the management of recurrent variceal bleeding prior to liver transplantation. Intra0Perative hemodynamic measurements suggest a theoretical advantage with TIPS. In a group of patients with advanced liver disease we report an outcome that is similar to patients treated with DSRS prior to liver transplantation. The role of TIPS in the treatment of nontransplant candidates remains to be clarified.

  15. Determination of blood flow through arteriovenous fistulae and shunts

    International Nuclear Information System (INIS)

    Lantz, B.M.T.; Holcroft, J.W.; Foerster, J.M.; Link, D.P.; Reid, M.H.

    1979-01-01

    A videodensitometric method for estimating relative flow was employed in a patient with a bovine arteriovenous fistula. Analogous arteriovenous communications of different sizes were created in two dogs for comparison. Local and general hemodynamic parameters were measured. The videodensitometric method proved to be highly accurate compared to electromagnetic flow readings and is the method of choice in estimating shunt flow in connection with routine angiography. (Auth.)

  16. Almost periodic solution of shunting inhibitory CNNs with delays

    Science.gov (United States)

    Chen, Anping; Cao, Jinde

    2002-06-01

    Using the Banach fixed point theorem, we obtain a sufficient condition for the existence of almost periodic solution of shunting inhibitory cellular neural networks {dx ij}/{dt}=-a ijx ij- limit∑C kl∈N r(i,j) C ijklf x kl(t-τ) x ij+L ij(t), the global attractivity of SICNNs is also obtained. An example is given to illustrate that the condition of our results are feasible.

  17. A case of repeated intracerebral hemorrhages secondary to ventriculoperitoneal shunt

    Directory of Open Access Journals (Sweden)

    Jinbing Zhao

    2015-03-01

    Full Text Available Ventriculoperitoneal shunt is a routinely performed treatment in neurosurgical department. Intracerebral hemorrhage, as a complication after shunt catheterization, is really rare but with high mortality. In this study, we reported a case of a 74-year-old man who suffered from repeated intracerebral hemorrhage after ventriculoperitoneal shunt. The first hemorrhage happened 63 h after the 1st surgery, and most hematomas were located in the ipsilateral occipital lobe and intraventricles, along the ventricular catheter. Fresh blood clot casts blocked the external ventricular draining catheter, which was inserted into the right front horn during the 3rd surgery, indicating new intraventricular bleeding happened. A large hematoma in ipsilateral frontal lobe was detected on the 3rd day after the removal of external ventricular draining catheter. Different hemorrhagic locations and time points were encountered on the same case. We discussed the possible causes of repeated hemorrhage for this case, and the pre-operative preparation including risk evaluation in future clinical work.

  18. Retinal complications after aqueous shunt surgical procedures for glaucoma.

    Science.gov (United States)

    Law, S K; Kalenak, J W; Connor, T B; Pulido, J S; Han, D P; Mieler, W F

    1996-12-01

    To assess retinal complications and to identify risk factors for retinal complications following aqueous shunt procedures. Records of 38 consecutive aqueous shunt procedures that were performed on 36 patients at the Eye Institute of the Medical College of Wisconsin, Milwaukee, from June 1993 to March 1995 (minimum follow-up, 6 months) were reviewed. The mean +/- SD follow-up was 11.4 +/- 5.2 months (median, 10.5 months). Twelve patients (32%) had the following retinal complications: 4 serous choroidal effusions (10%) that required drainage, 3 suprachoroidal hemorrhages (8%), 2 vitreous hemorrhages (5%), 1 rhegmatogenous retinal detachment (3%), 1 endophthalmitis (3%), and 1 scleral buckling extrusion (3%). Surgical procedures for retinal complications were required in 8 (67%) of these 12 patients. Visual acuity decreased 2 lines or more in 9 (75%) of these 12 patients. The median onset of a postoperative retinal complication was 12.5 days, with 10 patients (83%) experiencing complications within 35 days. Serous choroidal effusions developed in 10 other patients (26%), and these effusions resolved spontaneously. Visual acuity decreased 2 lines or more in 2 (20%) of these additional 10 patients. Patients who experienced serious retinal complications were significantly older, had a higher rate of hypertension, and postoperative ocular hypotony. Serious retinal complications were distributed evenly among patients with Krupin valves with discs and Molteno and Baerveldt devices. Experience with the Ahmed glaucoma valve implant was limited. Aqueous shunt procedures may be associated with significant retinal complications and subsequent visual loss.

  19. Exact bidirectional X -wave solutions in fiber Bragg gratings

    Science.gov (United States)

    Efremidis, Nikolaos K.; Nye, Nicholas S.; Christodoulides, Demetrios N.

    2017-10-01

    We find exact solutions describing bidirectional pulses propagating in fiber Bragg gratings. They are derived by solving the coupled-mode theory equations and are expressed in terms of products of modified Bessel functions with algebraic functions. Depending on the values of the two free parameters, the general bidirectional X -wave solution can also take the form of a unidirectional pulse. We analyze the symmetries and the asymptotic properties of the solutions and also discuss additional waveforms that are obtained by interference of more than one solution. Depending on their parameters, such pulses can create a sharp focus with high contrast.

  20. A psychophysically validated metric for bidirectional texture data reduction

    Czech Academy of Sciences Publication Activity Database

    Filip, Jiří; Chantler, M.J.; Green, P.R.; Haindl, Michal

    2008-01-01

    Roč. 27, č. 5 (2008), s. 138:1-138:11 ISSN 0730-0301 R&D Projects: GA AV ČR 1ET400750407; GA ČR GA102/08/0593 Institutional research plan: CEZ:AV0Z10750506 Keywords : Bidirectional Texture Functions * texture compression Subject RIV: BD - Theory of Information Impact factor: 3.383, year: 2008 http://library.utia.cas.cz/separaty/2008/RO/haindl-a psychophysically validated metric for bidirectional texture data reduction.pdf

  1. Transmicrocatheter local injection of ethanol to treat hepatocellular carcinoma with high flow arteriovenous shunts

    International Nuclear Information System (INIS)

    Guan Shouhai; Shan Hong; Jiang Zaibo; Huang Mingsheng; Zhu Kangshun; Li Zhengran; Meng Xiaochun

    2002-01-01

    Objective: To evaluate the feasibility and clinical effect of embolization therapy in treating the high flow hepatic arteriovenous shunts in hepatocellular carcinoma (HCC) by locally injected ethanol through microcatheter. Methods: Forty-one branches of arteriovenous shunts were treated by local ethanol infusion through microcatheter in 29 patients suffered with HCC. Angiography was performed to observe the embolization effect and influence to non-targeted vessels. Result: Forty-one branches of arteriovenous shunts in 29 patients were injected with ethanol locally. Each single shunt was infused 1-6 times. The dose of ethanol was 2-3 ml per time, and the total dose of ethanol was 2-12 ml. All shunting tracts were embolized, and all non-target vessels were protected fluently. Iodine-oil deposition was well in continued TACE. Their syndromes were improved or disappeared. Conclusion: Transmicrocatheter injection of ethanol could safely and effectively treat the hepatic arteriovenous shunts and make advantages to TACE in HCC

  2. Valved or valveless ventriculoperitoneal shunting in the treatment of post-haemorrhagic hydrocephalus

    DEFF Research Database (Denmark)

    Andreasen, Trine Hjorslev; Holst, Anders Vedel; Lilja, Alexander

    2016-01-01

    BACKGROUND: Implant infection and obstruction are major complications for ventriculoperitoneal shunts in patients with post-haemorrhagic hydrocephalus. In an effort to (1) reduce the incidence of these complications, (2) reduce the rate of shunt failure and (3) shorten the duration of neurosurgical...... hospitalisation, we have implemented valveless ventriculoperitoneal shunts at our department for adult patients with post-haemorrhagic hydrocephalus and haemorrhagic cerebrospinal fluid at the time of shunt insertion. METHODS: All adult patients (>18 years old) treated for post-haemorrhagic hydrocephalus.......3 %, p = 0.02), but a higher rate of overdrainage (10.3 % vs 2.6 %, p = 0.04). CONCLUSION: The use of a valveless shunting for patients with post-haemorrhagic hydrocephalus results in shorter duration of neurosurgical hospitalisation and lower rate of shunt infection, although these advantages should...

  3. Laparoscopic assisted ventriculoperitoneal shunt revisions as an option for pediatric patients with previous intraabdominal complications

    Directory of Open Access Journals (Sweden)

    Fernanda O. de Carvalho

    2014-04-01

    Full Text Available Multiple shunt failure is a challenge in pediatric neurosurgery practice and one of the most feared complications of hydrocephalus. Objective: To demonstrate that laparoscopic procedures for distal ventriculoperitoneal shunt failure may be an effective option for patients who underwent multiple revisions due to repetitive manipulation of the peritoneal cavity, abdominal pseudocyst, peritonitis or other situations leading to a “non reliable” peritoneum. Method: From March 2012 to February 2013, the authors reviewed retrospectively the charts of six patients born and followed up at our institution, which presented with previous intra-peritoneal complications and underwent ventriculoperitoneal shunt revision assisted by video laparoscopy. Results: After a mean follow-up period of nine months, all patients are well and no further shunt failure was identified so far. Conclusion: Laparoscopy assisted shunt revision in children may be, in selected cases, an effective option for patients with multiple peritoneal complications due to ventriculo-peritoneal shunting.

  4. Design strategy for the combined system of shunt passive and series active filters

    OpenAIRE

    Fujita, Hideki; Akagi, Hirofumi

    1991-01-01

    A design strategy for the combined power filter for a three-phase twelve-pulse thyristor rectifier is proposed. The shunt passive filter, which can minimize the output voltage of the series active filter, is designed and tested in a prototype model. A specially designed shunt passive filter makes it possible to reduce the required rating of the series active filter to 60% compared with a conventional shunt passive filter

  5. Phenotypic and chemotypic characterization of GABA-shunt mutants in Arabidopsis thaliana

    OpenAIRE

    Mekonnen, Dereje Worku

    2013-01-01

    Gamma-Aminobutyric acid (GABA) is a four carbon non protein amino acid, and the pathway that involves its production and degradation is called the GABA shunt. The GABA shunt is a short enzymatic pathway that involves three enzymes: glutamate decarboxylase (GAD), GABA transaminase (GABA-T) and succinic semi aldehyde dehydrogenase (SSADH). GABA shunt is conserved almost in all organisms studied so far. The pathway starts in the cytosol and finishes in mitochondria in higher organisms like plant...

  6. Haematology and coagulation profiles in cats with congenital portosystemic shunts.

    Science.gov (United States)

    Tzounos, Caitlin E; Tivers, Michael S; Adamantos, Sophie E; English, Kate; Rees, Alan L; Lipscomb, Vicky J

    2017-12-01

    Objectives The objectives of this study were, first, to report the haematological parameters and coagulation times for cats with a congenital portosystemic shunt (CPSS) and the influence of surgical shunt attenuation on these parameters; and, second, to identify any association between prolongation in coagulation profiles and incidence of perioperative haemorrhage. Methods This was a retrospective clinical study using client-owned cats with a CPSS. Signalment, shunt type (extra- or intrahepatic), degree of shunt attenuation (complete or partial), haematological parameters, prothrombin time (PT) and activated partial thromboplastin time (aPTT) test results, and occurrence of any perioperative clinical bleeding complications were recorded for cats undergoing surgical treatment of a CPSS at the Royal Veterinary College, UK, between 1994 and 2011. Results Forty-two cats were included. Thirty-six (85.7%) had an extrahepatic CPSS and six (14.3%) had an intrahepatic CPSS. Preoperatively, mean cell volume (MCV) and mean cell haemoglobin (MCH) were below the reference interval (RI) in 32 (76.2%) and 31 (73.8%) cats, respectively. Red blood cell count and mean cell haemoglobin concentration (MCHC) were above the RI in 10 (23.8%) and eight (19.1%) cats, respectively. Postoperatively, there were significant increases in haematocrit ( P = 0.044), MCV ( P = 0.008) and MCH ( P = 0.002). Despite the significant increase in MCV postoperatively, the median MCV postoperatively was below the RI, indicating persistence of microcytosis. Preoperatively, PT was above the upper RI in 14 cats (87.5%), and aPTT was above the upper RI in 11 cats (68.8%). No cat demonstrated a perioperative clinical bleeding complication. Conclusions and relevance Cats with a CPSS are likely to present with a microcytosis, but rarely present with anaemia, leukocytosis or thrombocytopenia. Surgical attenuation of the CPSS results in a significant increase in the HCT and MCV. Coagulation profiles in cats with a

  7. Intrahepatic porto-hepatic venous shunts in Rendu-Osler-Weber disease: imaging demonstration

    International Nuclear Information System (INIS)

    Matsumoto, Shunro; Mori, Hiromu; Yamada, Yasunari; Hayashida, Tomoko; Hori, Yuzo; Kiyosue, Hiro

    2004-01-01

    This study describes the imaging features of the intrahepatic portohepatic venous (PHV) shunt, which is a potential cause of portosystemic encephalopathy in Rendu-Osler-Weber disease. Six patients with Rendu-Osler-Weber disease (two men, four women; age range 42-73 years) were retrospectively studied. There were two from one family and three from another family. Of these patients, one was diagnosed with definitive portosystemic encephalopathy because of a psychiatric disorder. We retrospectively reviewed the radiological examinations, including abdominal angiography (n=6), three-phase dynamic helical computed tomography (CT; n=3), and conventional enhanced CT (n=1). In one patient, CT during angiography and CT angioportography were also performed. Evaluation was placed on the imaging features of intrahepatic PHV shunts. On angiography, intrahepatic PHV shunts showing multiple and small shunts <5 mm in diameter in an apparent network were detected in all patents. In two patients, a large shunt with a size of either 7 or 10 mm was associated. These intrahepatic PHV shunts were predominantly distributed in the peripheral parenchyma. Intrahepatic PHV shunts would be characterized by small and multiple shunts in an apparent network on the periphery with or without a large shunt. (orig.)

  8. Radiologic follow-up of the transjugular intrahepatic stent-shunt (TIPSS)

    International Nuclear Information System (INIS)

    Hansmann, H.J.; Noeldge, G.; Leutloff, U.; Radeleff, B.; Richter, G.M.

    2001-01-01

    The transjugular intrahepatic stent-shunt (TIPSS) is a well accepted minimal invasive therapy for complications of portal hypertension: recurrent variceal bleeding, refractory ascites and liver failure due to the Budd-Chiari syndrome. The high frequency of shunt stenoses and occlusions makes regular follow up examinations essential. Despite modern non invasive imaging methods direct portography still is the gold standard for shunt surveillance in TIPSS. Ultrasound is helpful to detect shunt dysfunction, but nevertheless its failure rate is considerable despite the use of contrast enhancers such as Levovist because of anatomic and physical limitations, particularly when TIPSS-tracts deep in the liver are present. Reintervention rates approach 90-100% after 24 months, with 100% in child's A patients with comparatively good liver function. However, a strict shunt surveillance program with early portography and reintervention when necessary guarantees high clinical success rates associated with very low rebleeding rates below 10%. Overall the secondary success rate is 80%. Secondary failures are mainly caused by lack of patient compliance during follow-up. In a subgroup of patients no shunt maturation is observed, requiring multiple shunt revisions. In cases of recurrent shunt occlusions an association with bile leaks is presumed. In selected cases patients with chronically recurrent shunt stenosis or occlusions may benefit from placement of TIPSS stent grafts. (orig.) [de

  9. Study on the Automatic Detection Method and System of Multifunctional Hydrocephalus Shunt

    Science.gov (United States)

    Sun, Xuan; Wang, Guangzhen; Dong, Quancheng; Li, Yuzhong

    2017-07-01

    Aiming to the difficulty of micro pressure detection and the difficulty of micro flow control in the testing process of hydrocephalus shunt, the principle of the shunt performance detection was analyzed.In this study, the author analyzed the principle of several items of shunt performance detection,and used advanced micro pressure sensor and micro flow peristaltic pump to overcome the micro pressure detection and micro flow control technology.At the same time,This study also puted many common experimental projects integrated, and successfully developed the automatic detection system for a shunt performance detection function, to achieve a test with high precision, high efficiency and automation.

  10. Embolization of portal-systemic shunts in cirrhotic patients with chronic recurrent hepatic encephalopathy

    International Nuclear Information System (INIS)

    Sakurabayashi, Shin; Sezai, Shuichi; Yamamoto, Yoshihiro; Hirano, Masanori; Oka, Hiroshi

    1997-01-01

    Purpose. To evaluate the efficacy of embolization of portal-systemic shunts in cirrhotic patients with chronic recurrent hepatic encephalopathy (CRHE). Methods. Seven cirrhotic patients with CRHE refractory to medical treatment (3 men and 4 women, mean age 66 years) were studied. Five patients had splenorenal shunts, 1 had a gastrorenal shunt, and 1 had an intrahepatic portal vein-hepatic vein shunt. Shunt embolization was performed using stainless steel coils, with a percutaneous transhepatic portal vein approach in 4 patients and a transrenal vein approach in 3 patients. Results. After embolization, the shunt disappeared in 4 patients on either ultrasound pulsed Doppler monitoring or portography. Complications observed in the 7 patients were fever, transient pleural effusion, ascites, and mild esophageal varices. For 3-6 months after embolization, the 4 patients whose shunts disappeared showed minimal or no reappearance of a shunt, and had no recurrence of encephalopathy. The serum ammonia levels decreased and electroencephalograms also improved. One of the 4 patients, who developed mild esophageal varices, required no treatment. Treatment was effective in 3 of the 4 patients (75%) who underwent embolization via a transhepatic portal vein. Conclusion. Transvascular embolization of shunts improved the outcome in 4 of 7 patients. The most effective embolization was achieved via the percutaneous transhepatic portal vein approach

  11. Predictors of Shunt Dysfunction and Overall Survival in Patients with Variceal Bleeding Treated with Transjugular Portosystemic Shunt Creation Using the Fluency Stent Graft.

    Science.gov (United States)

    Wan, Yue-Meng; Li, Yu-Hua; Xu, Ying; Wu, Hua-Mei; Li, Ying-Chun; Wu, Xi-Nan; Yang, Jin-Hui

    2018-01-16

    Transjugular intrahepatic portosystemic shunt (TIPS) is an established method for portal hypertension. This study was to investigate the long-term safety, technical success, and patency of TIPS, and to determine the risk factors and clinical impacts of shunt dysfunction. A total of 154 consecutive patients undergoing embolotherapy of gastric coronary vein and/or short gastric vein and TIPS creation were prospectively studied. Follow-up data included technical success, patency and revision of TIPS, and overall survival of patients. During the study, the primary and secondary technical success rates were 98.7% and 100%, respectively. Sixty-three patients developed shunt dysfunction, 30 with shunt stenosis and 33 with shunt occlusion. The cumulative 60-month primary, primary assisted, and secondary patency rates were 19.6%, 43.0%, and 93.4%, respectively. The cumulative 60-month overall survival rates were similar between the TIPS dysfunction group and the TIPS non-dysfunction group (68.6% vs. 58.6%, P = .096). Baseline portal vein thrombosis (P value of 8.5 had 77.8% sensitivity and 64.8% specificity. The long-term safety, technical success, and patency of TIPS were good; baseline portal vein thrombosis, use of bare stents, and PPG were significantly associated with shunt dysfunction; shunt dysfunction has little impact on patients' long-term survival because of high secondary patency rates. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  12. Bidirectional converter interface for a battery energy storage test bench

    DEFF Research Database (Denmark)

    Trintis, Ionut; Thomas, Stephan; Blank, Tobias

    2011-01-01

    This paper presents the bidirectional converter interface for a 6 kV battery energy storage test bench. The power electronic interface consists a two stage converter topology having a low voltage dc-ac grid connected converter and a new dual active bridge dc-dc converter with high transformation...

  13. Longitudinal Bidirectional Relations between Adolescents' Sympathy and Prosocial Behavior

    Science.gov (United States)

    Carlo, Gustavo; Padilla-Walker, Laura M.; Nielson, Matthew G.

    2015-01-01

    Despite the importance of understanding sympathy and prosocial behaviors, research on the development of these tendencies in adolescence remains relatively sparse. In the present study, we examined age trends and bidirectional longitudinal relations in sympathy and prosocial behaviors across early to middle adolescents. Participants were 500…

  14. Bidirectional Relations between Authoritative Parenting and Adolescents' Prosocial Behaviors

    Science.gov (United States)

    Padilla-Walker, Laura M.; Carlo, Gustavo; Christensen, Katherine J.; Yorgason, Jeremy B.

    2012-01-01

    This study examined the bidirectional relations between authoritative parenting and adolescents' prosocial behavior over a 1-year time period. Data were taken from Time 2 and 3 of the Flourishing Families Project, and included reports from 319 two-parent families with an adolescent child (M age of child at Time 2 = 12.34, SD = 1.06, 52% girls).…

  15. Bidirectional Associations among Sensitive Parenting, Language Development, and Social Competence

    Science.gov (United States)

    Barnett, Melissa A.; Gustafsson, Hanna; Deng, Min; Mills-Koonce, W. Roger; Cox, Martha

    2012-01-01

    Rapid changes in language skills and social competence, both of which are linked to sensitive parenting, characterize early childhood. The present study examines bidirectional associations among mothers' sensitive parenting and children's language skills and social competence from 24 to 36?months in a community sample of 174 families. In addition,…

  16. Bidirectional electrostatic linear shuffle motor with two degrees of freedom

    NARCIS (Netherlands)

    Sarajlic, Edin; Berenschot, Johan W.; Fujita, H.; Krijnen, Gijsbertus J.M.; Elwenspoek, Michael Curt

    2005-01-01

    We report on an electrostatic linear inchworm micromotor with two translational degrees-of-freedom. The motor employs built-in mechanical leverage to convert normal deflection of a flexible cross-plate into a small in-plane step and four electrostatic clamps to enable bidirectional inchworm motion

  17. Parenting and Children's Externalizing Behavior: Bidirectionality during Toddlerhood

    Science.gov (United States)

    Verhoeven, Marjolein; Junger, Marianne; van Aken, Chantal; Dekovic, Maja; van Aken, Marcel A. G.

    2010-01-01

    This study examined the bidirectional relationship between parenting and boys' externalizing behaviors in a four-wave longitudinal study of toddlers. Participants were 104 intact two-parent families with toddler sons. When their sons were 17, 23, 29, and 35 months of age, mothers and fathers reported on a broad range of parenting dimensions…

  18. Parenting and children's externalizing behavior: Bidirectionality during toddlerhood

    NARCIS (Netherlands)

    Verhoeven, Marjolein; Junger, Marianne; van Aken, Chantal; Dekovic, Maja; van Aken, Marcel A.G.

    2010-01-01

    This study examined the bidirectional relationship between parenting and boys' externalizing behaviors in a four-wave longitudinal study of toddlers. Participants were 104 intact two-parent families with toddler sons. When their sons were 17, 23, 29, and 35 months of age, mothers and fathers

  19. "Figuring" Bidirectional Home and School Connections along the Biliteracy Continuum

    Science.gov (United States)

    Fránquiz, María E.; Leija, María G.; Garza, Irene

    2015-01-01

    This article centers on the significant practices identified by bilingual teachers who participated in Proyecto Bilingüe, a specialized master's degree program. The notion of bidirectional theory of bilingual pedagogy and the theoretical construct of the continua of biliteracy are utilized to illustrate how the teachers centered home and school…

  20. Family of multiport bidirectional DC-DC converters

    NARCIS (Netherlands)

    Tao, H.; Kotsopoulos, A.; Duarte, J.L.; Hendrix, M.A.M.

    2006-01-01

    Multiport DC-DC converters are of potential interest in applications such as generation systems utilising multiple sustainable energy sources. A family of multiport bidirectional DC-DC converters derived from a general topology is presented. The topology shows a combination of DC-link and magnetic

  1. Primary Parallel Isolated Boost Converter with Bidirectional Operation

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Mira Albert, Maria del Carmen; Sen, Gökhan

    2012-01-01

    This paper presents a bidirectional dc/dc converter operated with batteries both in the input and output. Primary parallel isolated boost converter (PPIBC) with transformer series connection on the high voltage side is preferred due to its ability to handle high currents in the low voltage side. ...... and output battery banks with a defined ramp....

  2. A Current-Fed Isolated Bidirectional DC-DC Converter

    DEFF Research Database (Denmark)

    Sun, Xiaofeng; Wu, Xiaoying; Shen, Yanfeng

    2017-01-01

    This paper proposes a current-fed isolated bidirectional DC-DC converter (CF-IBDC) which has the advantages of wide input voltage range, low input current ripple, low conduction losses, and soft switching over the full operating range. Compared with conventional CF-IBDCs, the voltage spikes...

  3. A new setup to measure bidirectional reflectance distribution functions

    NARCIS (Netherlands)

    Roosjen, P.P.J.; Clevers, J.G.P.W.; Bartholomeus, H.

    2012-01-01

    The Plant Facility, a new laboratory goniometer system, built by the Wageningen University has been tested in order to take bidirectional reflectance distribution function (BRDF) measurements. An ASD FieldSpec 3 spectroradiometer mounted on an industrial robot arm is able to measure small targets

  4. Bidirectional reflectance distribution function measurements and analysis of retroreflective materials.

    Science.gov (United States)

    Belcour, Laurent; Pacanowski, Romain; Delahaie, Marion; Laville-Geay, Aude; Eupherte, Laure

    2014-12-01

    We compare the performance of various analytical retroreflecting bidirectional reflectance distribution function (BRDF) models to assess how they reproduce accurately measured data of retroreflecting materials. We introduce a new parametrization, the back vector parametrization, to analyze retroreflecting data, and we show that this parametrization better preserves the isotropy of data. Furthermore, we update existing BRDF models to improve the representation of retroreflective data.

  5. Optical properties (bidirectional reflectance distribution function) of shot fabric

    NARCIS (Netherlands)

    Lu, Rong; Koenderink, Jan J.; Kappers, Astrid M L

    2000-01-01

    To study the optical properties of materials, one needs a complete set of the angular distribution functions of surface scattering from the materials. Here we present a convenient method for collecting a large set of bidirectional reflectance distribution function (BRDF) samples in the hemispherical

  6. Experience and outcome of ventricular-atrial shunt: a multi centre study

    International Nuclear Information System (INIS)

    Akhtar, N.; Khan, A.A.; Yousaf, M.

    2015-01-01

    Ventriculoperitoneal (VP) shunt has been widely utilized in the treatment of hydrocephalus as a safe option but there is recent literature evidence that ventricularatrial (VA) shunt is not as notorious for its complications as proclaimed, to analyse and report our success with this procedure we conducted our study. Methods: A total of 64 patients undergoing VA shunting were included in this case series study conducted at RMC and Allied hospital Rawalpindi. The data was collected over a period of 4 years from, 1st June 2010 to 1st June 2015. Result: Our study included 64 patients who underwent a VA shunt for hydrocephalus. Their age ranged from 25 to 75 years. Most of the patients were females (60%). The following complications were observed with 2 (3.12%) patients having blockage of the shunt at the neck, 3 (4.68%) suffered from glomerulonephritis, 2 (3.1%) had post-operative neck hematoma, 4 (6.25 %) had wound infection, short lower end of the tube was found in 3 (4.68%), migrated lower end (into the subclavian) was seen in 1 (1.56%). Mortality was 1(1.56%). These results were comparable to other studies. Conclusion: Neurosurgeons have been doing a VA shunt as a second procedure, after a VP shunt when the need due to a complication was encountered. We however share our experience regarding ventriculo-atrial shunting, as first choice procedure, because of its low incidence of shunt blockage unlike VP shunt, which has high rate of shunt blockage and therefore warrants repeated surgeries. (author)

  7. Investigating PID Shunting in Polycrystalline Silicon Modules via Multiscale, Multitechnique Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, Steven P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Moseley, John [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Norman, Andrew [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hacke, Peter L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Johnston, Steven [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Al-Jassim, Mowafak M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stokes, Adam [Colorado School of Mines; Gorman, Brian [Colorado School of Mines

    2018-02-27

    We investigated the potential-induced degradation (PID) shunting mechanism in multicrystalline-silicon photovoltaic modules by using a multiscale, multitechnique characterization approach. Both field-stressed modules and laboratory-stressed mini modules were studied. We used photoluminescence, electroluminescence, and dark lock-in thermography imaging to identify degraded areas at the module scale. Small samples were then removed from degraded areas, laser marked, and imaged by scanning electron microscopy. We used simultaneous electron-beam induced current imaging and focused ion beam milling to mark around PID shunts for chemical analysis by time-of-flight secondary-ion mass spectrometry or to isolate individual shunt defects for transmission electron microscopy and atom-probe tomography analysis. By spanning a range of 10 orders of magnitude in size, this approach enabled us to investigate the root-cause mechanisms for PID shunting. We observed a direct correlation between recombination active shunts and sodium content. The sodium content in shunted areas peaks at the SiNX/Si interface and is consistently observed at a concentration of 0.1% to 2% in shunted areas. Analysis of samples subjected to PID recovery, either activated by electron beam or thermal effects only, reveals that recovery of isolated shunts correlates with diffusion of sodium out of the structural defects to the silicon surface. We observed the role of oxygen and chlorine in PID shunting and found that those species - although sometimes present in structural defects where PID shunting was observed - do not play a consistent role in PID shunting.

  8. Endoscopic Third Ventriculostomy Instead of Shunt Revision in Children Younger Than 3 Years of Age.

    Science.gov (United States)

    Zhao, Rui; Shi, Wei; Yang, Haowei; Li, Hao

    2016-04-01

    Endoscopic third ventriculostomy (ETV) is a valuable option in the treatment of shunt failure, but no clinical data exist for young children. The aim of this study was to elucidate the role of ETV in patients younger than 3 years of age with shunt malfunction. A cohort of 37 patients younger than 3 years of age with shunt malfunction underwent ETV instead of shunt revision. Patients' preoperative condition and medical history were studied to determine the impact of a number of variables on outcome. The Fisher exact test was used to assess differences among groups. Median age at ETV was 21.6 months (8-36 months). Diagnosis was obstructive hydrocephalus in 24 patients and communicating hydrocephalus in 13. Median age at initial shunt placement was 3.2 months (10 days to 30 months). The etiology of shunt malfunction was obstruction (n = 27) or infection (n = 10). Overall ETV failure rate was 40.5% (15/37). Patients whose age at initial shunt placement was <6 months and/or who had a preterm birth history had higher relative rates of ETV failure. Other variables, including type of hydrocephalus, interval between initial shunt placement and ETV, history of intraventricular bleeding and/or infection, and etiology of shunt malfunction, did not significantly affect the final outcome. Patients younger than 3 years with obstructive or communicating hydrocephalus may benefit from ETV in the event of shunt malfunction and have about a 60% probability of becoming shunt free. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Exercise-induced arteriovenous intrapulmonary shunting in dogs.

    Science.gov (United States)

    Stickland, Michael K; Lovering, Andrew T; Eldridge, Marlowe W

    2007-08-01

    We have previously shown, using contrast echocardiography, that intrapulmonary arteriovenous pathways are inducible in healthy humans during exercise; however, this technique does not allow for determination of arteriovenous vessel size or shunt magnitude. The purpose of this study was to determine whether large-diameter (more than 25 microm) intrapulmonary arteriovenous pathways are present in the dog, and whether exercise recruits these conduits. Through the right forelimb, 10.8 million 25-microm stable isotope-labeled microspheres (BioPAL, Inc., Worcester, MA) were injected either at rest (n = 8) or during high-intensity exercise (6- 8 mph, 10-15% grade, n = 6). Systemic arterial blood was continuously sampled during and for 3 minutes after injection. After euthanasia, tissue samples were obtained from the heart, liver, kidney, and skeletal muscle. In addition, 25- and 50-microm microspheres were infused into four isolated dog lungs that were ventilated and perfused at constant pressures similar to exercise. Blood and tissue samples were commercially analyzed for the presence of microspheres. No microspheres were detected in the arterial blood or tissue samples from resting dogs. In contrast, five of six exercising dogs showed evidence of exercise-induced intrapulmonary arteriovenous shunting, as microspheres were detected in arterial blood and/or tissue. Furthermore, shunt magnitude was calculated to be 1.4 +/- 0.8% of cardiac output (n = 3). Evidence of intrapulmonary arteriovenous anastomoses was also found in three of four isolated lungs. Consistent with previous human findings, these data demonstrate that intrapulmonary arteriovenous pathways are functional in the dog and are recruited with exercise.

  10. Immunohistochemical analysis of restenotic tissue after transjugular portosystemic shunt

    International Nuclear Information System (INIS)

    Lu Qin; An Yanli; Deng Gang; Fang Wen; Zhu Guangyu; Li Guozhao; Wei Xiaoying; Liu Yuanyuan; Teng Gaojun

    2005-01-01

    Objective: To investigate the changes of several restenotic tissue elements after transjugular portosystemic shunt, and to provide more informations for the mechanism of TIPS restenosis. Methods: TIPS was performed in 6 swine to set up TIPS animal models. 14-21 days after operation, the models were sacrificed to obtain the TIPS tissues for pathological examinations, including electric microscope, HE staining, and immunohistochemical staining of anti-SMC-actin-α, PCNA, Vementin, myoglobulin, eNOS and iNOS. Then , the results were comparatively analyzed between TIPS obstructed shunt tissues and non-obstructed shunt tissues. Results: Restenosis was occurred with different degrees in 4 swine of the 6 TIPS models. Electric microscopic results showed that the restenosis tissues were composed of over proliferated collagen, SMCs and fibroblasts. Anti-SMC-actin-α and PCNA were strongly positive expression in restenotic tissues, and also positive in patent tissues. Vimentin expressed strongly in unstenotic tissues, on the contrary, it expressed obviously weaker in restenotic tissues. Myoglobulin expressed more strongly in restenotic tissues and weakened in unstenotic tissues. eNOS expressed positive in normal liver tissues, and expressed weaker near TIPS restenotic tissues. iNOS showed stronger expression in restenotic tissues and could hardly expressed in normal liver tissues. Conclusions: Restenotic rate may be 67% in TIPS swine models. Restenotic tissues may be mainly composed of proliferated SMCs positively expressed anti-SMC-actin-α with strong ability of movement. eNOS may be expressed in normal liver tissues and instead iNOS be expressed in strongly injured liver tissues. (authors)

  11. Clinical results of the transjugular intrahepatic portosystemic shunt

    Energy Technology Data Exchange (ETDEWEB)

    Park, Auh Whan; Sim, Jae In; Ryeom, Hun Kyu; Kim, Yong Joo [Kyungpook National University Hospital, Daegu (Korea, Republic of)

    1994-04-15

    To evaluate the clinical results of transjugular intrahepatic portosystemic shunt(TIPS) for the control of variceal bleeding. TIPS creation was attempted in 23 patients with endoscopically confirmed variceal bleeding. Most patients had multiple episodes of bleeding in the past and have been treated with multiple endoscopic sclerotherapies. Pre-and post-procedural hepatic and portal vein pressures were measured. After creation of TIPS patients were followed up at regular intervals. TIPS has been successfully accomplished in 22 of 23 patients using Wallstent(n = 21) and Strecker stent(n = 1). Immediate bleeding control was achieved in all patients with shunt creation. No procedure-related complication was noted. Portal vein pressure was reduced from 30.7 {+-} 5.8 mmHg to 20.8 {+-} 4.7 mmHg. The mean pressure gradient of portosystemic shunt dropped from 22.8 {+-} 6.0 prior to TIPS to 12.2 {+-} 4.1 immediately after. During the follow-up period (6-556 days, mean; 10 months), seven patients died; progressive hepatic failure (n 4), variceal rebleeding (n = 2), and respiratory failure(n = 1). Hepatic encephalopathy after TIPS was noted in 7 patients(31.8%). Variceal rebleeding occurred in 3 patients(13.6%). The remaining 15 patients have survived an average of 11 months. This results suggest that TIPS is a safe and effective method for lowering portal pressure and controlling variceal bleeding. Furthermore if these initial results are encouraged by further long-term observation, TIPS could replace endoscopic and risky surgical intervention.

  12. Case of right atrial myxoma with right to left shunt

    Energy Technology Data Exchange (ETDEWEB)

    Nakai, Kenji; Suzuki, Tomoyuki; Ohzeki, Tetsuro (Iwate Medical Coll., Morioka (Japan). School of Medicine)

    1982-12-01

    A case of 49-year-old woman with right atrial myxoma resulting to right to left shunt, diagnosed by cardiac pool isotope image, was reported. She was admitted to our clinic because of progressive shortness of breath. At admission lip cyanosis was noted. Laboratory data included polycythemia, low O/sub 2/ saturation (89%) and high erythrocyte sedimentation rate (65 mm/1 h). Chest x-p showed slight right atrial enlargement, but no pulmonary congestion. The electrocardiogram showed sinus regular rhythm with biphasic p wave in leads II, III, aVf. Although 1st heart sound at the apex was splited, no heart murmur was heard. In usual echocardiographic approach, no abnormal echogram was obtained in the right ventricular region. Lung perfusion scintiscan with Tc-99 m-MAA showed visualization of thyroid gland and kidney, which suggested intracardiac right-to-left shunt. Cardiac pool image with Tc-99m-HSA revealed large photo-deficient area in the right atrium and early visualization of aortic arch. Computor tomography showed large round low density region 8 x 7 cm in size. Based on their findings, this patient was diagnosed as right atrial tumor. At operation a large tumor (diameter 8 x 7 x 7 cm, weight 160g) filled the lower part of the right atrium and was adherent to the anterolateral wall in the right atrium. As a cause of R-L shunt, streched foramen ovale (5 x 10 mm) was found. Tumor histology was typical of atrial myxoma. Post-operative gated cardiac isotope image showed no evidence of residual atrial tumor. Cardiac blood pool isotope imaging was a method for the noninvasive detection and assessment of right atrial myxoma.

  13. Shunting arc plasma source for pure carbon ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y. [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2012-02-15

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA/mm{sup 2} at the peak of the pulse.

  14. Shunting arc plasma source for pure carbon ion beam.

    Science.gov (United States)

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse.

  15. Ectopic cystoperitoneal shunt demonstrated by valvulography. A case report

    Energy Technology Data Exchange (ETDEWEB)

    Jofre, M J; Sierralta, M P [Military Hospital Nuclear Medicine Department, Santiago (Chile)

    2002-09-01

    The most important and frequent complications in the management of hydrocephalus treated with a derivation system are the infection and obstruction of the ventriculoperitoneal or ventriculoatrial shunt. However, another less frequent problem is the migration of the distal catheter. The case report presented is a 20 year-old girl who started, when she was 12, with severe headaches and epileptogenic seizures. She was diagnosed with a left parietotemporal aracnoidal cyst and a cystoperitoneal shunt was installed. However, she continued to have headaches. In September 1999, the derivation system was controlled with a radionuclide valvulography, which demonstrated shunt patency, with mild ectasis in the distal region. In July 2000, another valvulography showed a malfunction of the cystoperitoneal system. The distal catheter was surgically reviewed and repositioned. A few months of being asymptomatic, the headaches returned with a cough, which didn't respond to treatment. In February of 2002, she was referred to the Military Hospital Nuclear Medicine Department and a radionuclide valvulography was performed with 370 MBq of Tc99m-DTPA, injected in the derivative system reservoir. Images showed a slow descension of the radionuclide until the xifoides region where the distal catheter had formed a loop into the chest. Free activity was observed at the end of the catheter with another abnormal traject in the middle chest up to the top of the sternum. A pumping test was done and the patient coughed and said that she 'felt water' in her mouth. A simple abdomen X-ray was performed confirming the distal catheter in the upper side of the diaphragm. A third surgery was performed demonstrating that the catheter had an intraperitoneal loop with the distal end in the chest. They pulled the catheter and the distal end was repositioned into the peritoneal cavity, controlling its functioning. A simple abdomen X-ray verified the position. In the following days the patient had no headache

  16. Ectopic cystoperitoneal shunt demonstrated by valvulography. A case report

    International Nuclear Information System (INIS)

    Jofre, M.J.; Sierralta, M.P.

    2002-01-01

    The most important and frequent complications in the management of hydrocephalus treated with a derivation system are the infection and obstruction of the ventriculoperitoneal or ventriculoatrial shunt. However, another less frequent problem is the migration of the distal catheter. The case report presented is a 20 year-old girl who started, when she was 12, with severe headaches and epileptogenic seizures. She was diagnosed with a left parietotemporal aracnoidal cyst and a cystoperitoneal shunt was installed. However, she continued to have headaches. In September 1999, the derivation system was controlled with a radionuclide valvulography, which demonstrated shunt patency, with mild ectasis in the distal region. In July 2000, another valvulography showed a malfunction of the cystoperitoneal system. The distal catheter was surgically reviewed and repositioned. A few months of being asymptomatic, the headaches returned with a cough, which didn't respond to treatment. In February of 2002, she was referred to the Military Hospital Nuclear Medicine Department and a radionuclide valvulography was performed with 370 MBq of Tc99m-DTPA, injected in the derivative system reservoir. Images showed a slow descension of the radionuclide until the xifoides region where the distal catheter had formed a loop into the chest. Free activity was observed at the end of the catheter with another abnormal traject in the middle chest up to the top of the sternum. A pumping test was done and the patient coughed and said that she 'felt water' in her mouth. A simple abdomen X-ray was performed confirming the distal catheter in the upper side of the diaphragm. A third surgery was performed demonstrating that the catheter had an intraperitoneal loop with the distal end in the chest. They pulled the catheter and the distal end was repositioned into the peritoneal cavity, controlling its functioning. A simple abdomen X-ray verified the position. In the following days the patient had no headache

  17. The CHESS score: a simple tool for early prediction of shunt dependency after aneurysmal subarachnoid hemorrhage.

    Science.gov (United States)

    Jabbarli, R; Bohrer, A-M; Pierscianek, D; Müller, D; Wrede, K H; Dammann, P; El Hindy, N; Özkan, N; Sure, U; Müller, O

    2016-05-01

    Acute hydrocephalus is an early and common complication of aneurysmal subarachnoid hemorrhage (SAH). However, considerably fewer patients develop chronic hydrocephalus requiring shunt placement. Our aim was to develop a risk score for early identification of patients with shunt dependency after SAH. Two hundred and forty-two SAH individuals who were treated in our institution between January 2008 and December 2013 and survived the initial impact were retrospectively analyzed. Clinical parameters within 72 h after the ictus were correlated with shunt dependency. Independent predictors were summarized into a new risk score which was validated in a subsequent SAH cohort treated between January and December 2014. Seventy-five patients (31%) underwent shunt placement. Of 23 evaluated variables, only the following five showed independent associations with shunt dependency and were subsequently used to establish the Chronic Hydrocephalus Ensuing from SAH Score (CHESS, 0-8 points): Hunt and Hess grade ≥IV (1 point), location of the ruptured aneurysm in the posterior circulation (1 point), acute hydrocephalus (4 points), the presence of intraventricular hemorrhage (1 point) and early cerebral infarction on follow-up computed tomography scan (1 point). The CHESS showed strong correlation with shunt dependency (P = 0.0007) and could be successfully validated in both internal SAH cohorts tested. Patients scoring ≥6 CHESS points had significantly higher risk of shunt dependency (P CHESS may become a valuable diagnostic tool for early estimation of shunt dependency after SAH. Further evaluation and external validation will be required in prospective studies. © 2016 EAN.

  18. Cellophane banding for the gradual attenuation of single extrahepatic portosystemic shunts in eleven dogs.

    Science.gov (United States)

    Youmans, K R; Hunt, G B

    1998-08-01

    To evaluate the efficacy and short term effects of a cellophane banding technique for progressive attenuation of canine single extrahepatic portosystemic shunts. A prospective trial of 11 dogs with single congenital extrahepatic shunts. Rectal ammonia tolerance testing and routine biochemical tests were performed preoperatively on all dogs. In seven dogs, preoperative abdominal Doppler ultrasonography was also performed. Exploratory laparotomy revealed a single extrahepatic portocaval shunt in each animal, which was attenuated using a cellophane band with an internal diameter of 2 to 3 mm. The abdomen was closed routinely. Follow-up biochemical analysis and abdominal Doppler ultrasonography or splenoportography were performed postoperatively. The shunt was not amenable to total ligation in 11 dogs, based upon reported criteria. All dogs recovered uneventfully from surgery without evidence of portal hypertension, and showed clinical improvement thereafter. Shunt occlusion was deemed to have occurred in 10 dogs based on resolution of biochemical and/or sonographic abnormalities. One dog continued to have sonographic evidence of portosystemic shunting when evaluated 3 weeks after surgery, despite normal ammonia tolerance, but was lost to subsequent follow-up. Two dogs, in which 3 mm cellophane bands were placed, experienced delayed shunt occlusion. Cellophane banding is simple to perform, and causes progressive attenuation of single extrahepatic shunts in dogs. Further work is needed to determine the maximum diameter of a cellophane band which will produce total attenuation, and the long-term safety and reliability of the treatment.

  19. Multi-resonant electromagnetic shunt in base isolation for vibration damping and energy harvesting

    Science.gov (United States)

    Pei, Yalu; Liu, Yilun; Zuo, Lei

    2018-06-01

    This paper investigates multi-resonant electromagnetic shunts applied to base isolation for dual-function vibration damping and energy harvesting. Two multi-mode shunt circuit configurations, namely parallel and series, are proposed and optimized based on the H2 criteria. The root-mean-square (RMS) value of the relative displacement between the base and the primary structure is minimized. Practically, this will improve the safety of base-isolated buildings subjected the broad bandwidth ground acceleration. Case studies of a base-isolated building are conducted in both the frequency and time domains to investigate the effectiveness of multi-resonant electromagnetic shunts under recorded earthquake signals. It shows that both multi-mode shunt circuits outperform traditional single mode shunt circuits by suppressing the first and the second vibration modes simultaneously. Moreover, for the same stiffness ratio, the parallel shunt circuit is more effective at harvesting energy and suppressing vibration, and can more robustly handle parameter mistuning than the series shunt circuit. Furthermore, this paper discusses experimental validation of the effectiveness of multi-resonant electromagnetic shunts for vibration damping and energy harvesting on a scaled-down base isolation system.

  20. Ventriculoperitoneal shunt for treatment of hydrocephalus in a French bulldog puppy

    Science.gov (United States)

    Giacinti, Jolene A.

    2016-01-01

    A 6.5-week-old bulldog was presented with lethargy, anorexia, and stunted growth. A domed skull, ventrolateral strabismus, hypermetria, and delayed hopping were observed. Congenital hydrocephalus was diagnosed and a ventriculoperitoneal shunt was placed. After surgery, a shunt obstruction occurred but resolved with treatment. The puppy responded well and neurological deficits continued to improve after surgery. PMID:26933271

  1. Medication overuse as a cause of chronic headache in shunted hydrocephalus patients

    DEFF Research Database (Denmark)

    Willer, Lasse; Jensen, R H; Juhler, M

    2010-01-01

    To highlight the group of hydrocephalus patients known to have a long history of shunt revisions and refractory chronic headache. When a shunt in perfect working order has no effect on headache, other causes of headache should be investigated. In this paper, patients with medication overuse...

  2. Creation of transcatheter aortopulmonary and cavopulmonary shunts using magnetic catheters: feasibility study in swine.

    Science.gov (United States)

    Levi, Daniel S; Danon, Saar; Gordon, Brent; Virdone, Nicky; Vinuela, Fernando; Shah, Sanjay; Carman, Greg; Moore, John W

    2009-05-01

    Surgical shunts are the basic form of palliation for many types of congenital heart disease. The Glenn shunt (superior cavopulmonary connection) and central shunt (aortopulmonary connection) represent surgical interventions that could potentially be accomplished by transcatheter techniques. We sought to investigate the efficacy of using neodymium iron boron (NdFeB) magnetic catheters to create transcatheter cavopulmonary and aortopulmonary shunts. NdFeB magnets were machined and integrated into catheters. "Target" catheters were placed in the pulmonary arteries (PAs), and radiofrequency "perforation" catheters were placed in either the descending aorta (DAo) for central shunts or the superior vena cava (SVC) for Glenn shunts. The magnet technique or "balloon target" method was used to pass wires from the DAo or the SVC into the PA. Aortopulmonary and cavopulmonary connections were then created using Atrium iCAST covered stents. Magnet catheters were used to perforate the left pulmonary artery from the DAo, thereby establishing a transcatheter central shunt. Given the orientation of the vasculature, magnetic catheters could not be used for SVC-to-PA connections; however, perforation from the SVC to the right pulmonary artery was accomplished with a trans-septal needle and balloon target. Transcatheter Glenn or central shunts were successfully created in four swine.

  3. 21 CFR 882.5550 - Central nervous system fluid shunt and components.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Central nervous system fluid shunt and components... Central nervous system fluid shunt and components. (a) Identification. A central nervous system fluid... central nervous system to an internal delivery site or an external receptacle for the purpose of relieving...

  4. Medication overuse as a cause of chronic headache in shunted hydrocephalus patients

    DEFF Research Database (Denmark)

    Willer, Lasse; Jensen, R H; Juhler, M

    2010-01-01

    To highlight the group of hydrocephalus patients known to have a long history of shunt revisions and refractory chronic headache. When a shunt in perfect working order has no effect on headache, other causes of headache should be investigated. In this paper, patients with medication overuse...... headache are identified and the positive effect of medication withdrawal are described....

  5. l-Arginine Pathway Metabolites Predict Need for Intra-operative Shunt During Carotid Endarterectomy

    DEFF Research Database (Denmark)

    Szabo, P; Lantos, J; Nagy, L

    2016-01-01

    lactate levels were increased during reperfusion (p = .02). The median pre-operative concentration of l-arginine was lower in patients requiring an intra-operative shunt than in patients without need of shunt (median: 30.3 μmol/L [interquartile range 24.4-34.4 μmol/L] vs. 57.6 μmol/L [interquartile range...

  6. Clinical and ultrasonographic criteria for using ventriculoperitoneal shunts in newborns with myelomeningocele

    Directory of Open Access Journals (Sweden)

    Jose Roberto Tude Melo

    2015-09-01

    Full Text Available Objective Hydrocephalus is one of the main complications associated with myelomeningocele (MM. This study aimed to identify clinical and ultrasonographic criteria for using ventriculoperitoneal (VP shunts in this group of patients.Method A retrospective cohort study, based on established protocol for VP shunt implant in hydrocephalic children with MM. Parameters used to guide the indication of VP shunts included measurement of head circumference (HC, evaluation of fontanels, and measurement of lateral ventricular atrium (LVA width by transcranial ultrasonography.Results 43 children were included in the analysis, of which 74% had hydrocephalus and required a VP shunt. These children had LVA width ≥ 15 mm, showed increased HC, or had bulging fontanels.Conclusion VP shunt is required in children with increased HC (≥ 2 standard deviation regarding age group, bulging fontanels, or LVA width of ≥ 15 mm after the closure of MM.

  7. Ventriculoperitoneal shunt-related infections caused by Staphylococcus epidermidis: pathogenesis and implications for treatment.

    LENUS (Irish Health Repository)

    Stevens, Niall T

    2012-12-01

    The insertion of medical devices, such as intraventricular shunts, is often complicated by infection leading to ventriculitis. Frequently, such infections result from colonisation and subsequent biofilm formation on the surfaces of the shunts by Staphylococcus epidermidis. The pathogenesis of neurosurgical shunt-related infection is complex with interactions between the pathogen, the device and the unique local immunological environment of the central nervous system (CNS). An ability to form biofilm, the main virulence determinant of Staphylococcus epidermidis, facilitates protection of the organism from the host defences while still initiating an immunological response. The presence of the blood brain barrier (BBB) and the biofilm itself also complicates treatment, which presents many challenges when managing shunt infections. A greater understanding of the interplay between S. epidermidis and the CNS could potentially improve the diagnosis, treatment and management of such infections. This review describes the pathogenesis, treatment and implications of S. epidermidis ventriculoperitoneal shunt-related infections, concentrating on recent research and the implications for treatment.

  8. Intrahepatic portal-hepatic venous shunt diagnosed by ultrasonography and computed tomography. Report of two cases

    Energy Technology Data Exchange (ETDEWEB)

    Shinagawa, Takashi; Iino, Yasuo; Ukaji, Haruyasu; Ishizuka, Masaharu

    1986-02-01

    Two cases of intrahepatic portal-hepatic venous shunt found by ultrasonography and computed tomography are reported. The first case came to the hospital because of hematuria. A large shunt between the portal vein and the hepatic vein was demonstrated by ultrasonography done for screening, and confirmed by percutaneous transhepatic portography (PTP). The second case was admitted because of cholelithiasis. Computed tomography with contrast enhancement revealed a dilated portal vein in the upper portion of the right lobe. It was subsequently shown by PTP to be a portal-hepatic venous shunt. Portal vein pressure and histological finding of the liver were normal in both cases. The etiology of the shunt was thought to be congenital in these cases for lack of liver disease, portal hypertension and history of trauma. Both cases had no history of hepatic encephalopathy and did not show any symptom attributable to the shunt.

  9. Communicating hydrocephalus due to cerebral venous sinus thrombosis treated with ventriculoperitoneal shunt

    Directory of Open Access Journals (Sweden)

    Rahul T Chakor

    2012-01-01

    Full Text Available Cerebral venous sinus thrombosis (CVT is a rare cerebrovascular disease with variable presentation. CVT rarely causes hydrocephalus. Communicating hydrocephalus due to CVT is extremely rare. We describe a patient of CVT presenting with chronic headache and communicating hydrocephalus. The patient was successfully treated with ventriculoperitoneal (VP shunt. A 40 year old man presented with moderate to severe headache since six months and progressive visual loss since two months. Head Computed tomogram showed mild hydrocephalus without obstruction. Lumbar puncture (LP demonstrated elevated pressure but was otherwise normal. Magnetic resonance venogram showed extensive CVT. Repeated CSF drainage and thecoperitoneal shunt did not relieve the severe headache hence a VP shunt was placed. Post shunt headache subsided with resolution of hydrocephalus. CVT can present as communicating hydrocephalus. Gradual reduction of intra-ventricular pressure by repeated LPs followed by VP shunt can safely treat hydrocephalus due to CVT.

  10. Quantitative determination of peripheral arterio-venous shunts by means of radioactively labelled microspheres

    International Nuclear Information System (INIS)

    Friese, K.H.

    1981-01-01

    In the present work a nuclear method of quantitative measurement of peripheral arterio-venous shunts with a whole-body scanner is standardized. This method, developed at the beginning of the 70s at Tuebingen, stands out in contrast with earlier measuring methods by the application of the theory of quantitative scintiscanning. This means that the scintigram obtained after injection of sup(99m)technetium-labelled human albumin microspheres into an artery before the shunt is corrected for the quantitative shunt calculation by several factors using a computer, to avoid systematic mistakes. For the standardization of the method, 182 scintigrams were taken during model experiments and experiments on animals and human beings. This method, having a deviation of 10% at most, is excellently suited for the quantitative determination of peripheral arterio-venous shunts. Already for a pulmonary activity of 3% a peripheral shunt is proved with 97.5% probability. (orig./MG) [de

  11. A rare cause of pediatric urinary incontinence: Ventriculoperitoneal shunt with bladder perforation

    Directory of Open Access Journals (Sweden)

    Manuel C See IV

    2016-04-01

    Full Text Available We present a case of 2-year-old boy with long term dysuria and intermittent incontinence, and new onset of fever and headache. Significant past medical history includes congenital hydrocephalus with a ventriculoperitoneal shunt placement two years prior to consult. On physical examination, a tubular structure was noted underneath the prepuce suspected to be the distal tip of ventriculoperitoneal shunt, which was confirmed by kidney, ureter and bladder (KUB X-ray and CT scan. Patient was treated with a novel approach of extraperitoneal removal of ventriculoperitoneal shunt distal tip with cystorrhaphy via a low transverse pfannenstiel incision, separate left ventriculostomy tube insertion and complete removal of ventriculoperitoneal shunt from the right ventricle. This report accounts a rare pediatric case with ventriculoperitoneal shunt perforation into a normal bladder successfully treated with mini-open surgery.

  12. Tunable band gaps in acoustic metamaterials with periodic arrays of resonant shunted piezos

    International Nuclear Information System (INIS)

    Chen Sheng-Bing; Wen Ji-Hong; Wang Gang; Wen Xi-Sen

    2013-01-01

    Periodic arrays of resonant shunted piezoelectric patches are employed to control the wave propagation in a two-dimensional (2D) acoustic metamaterial. The performance is characterized by the finite element method. More importantly, we propose an approach to solving the conventional issue of the nonlinear eigenvalue problem, and give a convenient solution to the dispersion properties of 2D metamaterials with periodic arrays of resonant shunts in this article. Based on this modeling method, the dispersion relations of a 2D metamaterial with periodic arrays of resonant shunted piezos are calculated. The results show that the internal resonances of the shunting system split the dispersion curves, thereby forming a locally resonant band gap. However, unlike the conventional locally resonant gap, the vibrations in this locally resonant gap are unable to be completely localized in oscillators consisting of shunting inductors and piezo-patches

  13. Symptomatic spinal cord deformity secondary to a redundant intramedullary shunt catheter

    International Nuclear Information System (INIS)

    Quencer, R.M.; Montalvo Morse, B.M.; Green, B.A.; Eismont, F.J.

    1985-01-01

    Right arm pain, motor and sensory loss in the right arm and right facial numbness recurred in a 27 year old quadraplegic shortly after a posttraumatic spinal cord cyst (PTSCC) was shunted via a catheter into the adjacent subarachnoid space. Although shunt malfunction was clinically suspected, metrizamide computed tomography (MCT) suggested that redundancy of the catheter had caused deformity of the spinal cord. This hypothesis was confirmed at surgery when intraoperative spinal sonography (IOSS) showed that the spinal cord deformity at C 1 -C 2 disappeared when the catheter was withdrawn. This case shows that new or recurrent spinal cord symptoms may be due to a mechanical deformity of the cord rather than shunt malfunction, that restricting the length of the shunt catheter which is used to decompress PTSCCs is important, and that IOSS is an indispensible tool for visualizing the changes in spinal cord morphology during shunting procedures. (orig.)

  14. Intrahepatic portal-hepatic venous shunt diagnosed by ultrasonography and computed tomography

    International Nuclear Information System (INIS)

    Shinagawa, Takashi; Iino, Yasuo; Ukaji, Haruyasu; Ishizuka, Masaharu

    1986-01-01

    Two cases of intrahepatic portal-hepatic venous shunt found by ultrasonography and computed tomography are reported. The first case came to the hospital because of hematuria. A large shunt between the portal vein and the hepatic vein was demonstrated by ultrasonography done for screening, and confirmed by percutaneous transhepatic portography (PTP). The second case was admitted because of cholelithiasis. Computed tomography with contrast enhancement revealed a dilated portal vein in the upper portion of the right lobe. It was subsequently shown by PTP to be a portal-hepatic venous shunt. Portal vein pressure and histological finding of the liver were normal in both cases. The etiology of the shunt was thought to be congenital in these cases for lack of liver disease, portal hypertension and history of trauma. Both cases had no history of hepatic encephalopathy and did not show any symptom attributable to the shunt. (author)

  15. Management of Ventriculoperitoneal Shunt Infections in Adults: Analysis of Risk Factors Associated With Treatment Failure.

    Science.gov (United States)

    Pelegrín, Iván; Lora-Tamayo, Jaime; Gómez-Junyent, Joan; Sabé, Nuria; García-Somoza, Dolors; Gabarrós, Andreu; Ariza, Javier; Viladrich, Pedro Fernández; Cabellos, Carmen

    2017-04-15

    Little is known regarding the optimal treatment of ventriculoperitoneal (VP) shunt infections in adults. Our aim was to assess the efficacy of treatment strategies and to identify factors that predict failure. Retrospective, observational study of patients aged ≥12 years with VP shunt infections (1980 -2014). Therapeutic approaches were classified under 4 headings: only antibiotics (OA), one-stage shunt replacement (OSSR), two-stage shunt replacement (TSSR), and shunt removal without replacement (SR). The primary endpoint was failure of the treatment strategy, defined as the absence of definite cerebrospinal fluid (CSF) sterilization or related mortality. The parameters that predicted failure were analyzed using logistic regression. Of 108 episodes (51% male, median age 50 years), 86 were analyzed. Intravenous antibiotics were administered for a median of 19 days. Eighty episodes were treated using strategies that combined antibiotic and surgical treatment (37 TSSR, 24 SR, 19 OSSR) and 6 with OA. Failure occurred in 30% of episodes, mostly due to lack of CSF sterilization in OSSR and OA groups. Twelve percent died of related causes and 10% presented superinfection of the CSF temporary drainage/externalized peritoneal catheter. TSSR was the most effective strategy when VP shunt replacement was attempted. The only independent risk factor that predicted failure was retention of the VP shunt, regardless of the strategy. This is the largest series of VP shunt infections in adults reported to date. VP shunt removal, particularly TSSR when the patient is shunt dependent, remains the optimal choice of treatment and does not increase morbidity. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

  16. Shunt-dependent hydrocephalus: management style among members of the American Society of Pediatric Neurosurgeons.

    Science.gov (United States)

    Kraemer, Mark R; Sandoval-Garcia, Carolina; Bragg, Taryn; Iskandar, Bermans J

    2017-09-01

    OBJECTIVE The authors conducted a survey to evaluate differences in the understanding and management of shunt-dependent hydrocephalus among members of the American Society of Pediatric Neurosurgeons (ASPN). METHODS Surveys were sent to all 204 active ASPN members in September 2014. One hundred thirty responses were received, representing a 64% response rate. Respondents were asked 13 multiple-choice and free-response questions regarding 4 fundamental problems encountered in shunted-hydrocephalus management: shunt malfunction, chronic cerebrospinal fluid (CSF) overdrainage, chronic headaches, and slit ventricle syndrome (SVS). RESULTS Respondents agreed that shunt malfunction occurs most often as the result of ventricular catheter obstruction. Despite contrary evidence in the literature, most respondents (66%) also believed that choroid plexus is the tissue most often found in obstructed proximal catheters. However, free-text responses revealed that the respondents' understanding of the underlying pathophysiology of shunt obstruction was highly variable and included growth, migration, or adherence of choroid plexus, CSF debris, catheter position, inflammatory processes, and CSF overdrainage. Most respondents considered chronic CSF overdrainage to be a rare complication of shunting in their practice and reported wide variation in treatment protocols. Moreover, despite a lack of evidence in the literature, most respondents attributed chronic headaches in shunt patients to medical reasons (for example, migraines, tension). Accordingly, most respondents managed headaches with reassurance and/or referral to pain clinics. Lastly, there were variable opinions on the etiology of slit ventricle syndrome (SVS), which included early shunting, chronic overdrainage, and/or loss of brain compliance. Beyond shunt revision, respondents reported divergent SVS treatment preferences. CONCLUSIONS The survey shows that there is wide variability in the understanding and management of

  17. Transjugular Intrahepatic Portosystemic Shunts in Children with Biliary Atresia

    International Nuclear Information System (INIS)

    Huppert, Peter E.; Goffette, Pierre; Astfalk, Wolfgang; Sokal, Emil M.; Brambs, Hans-Juergen; Schott, Ullrich; Duda, Stephan H.; Schweizer, Paul; Claussen, Claus D.

    2002-01-01

    Purpose: We retrospectively evaluated the technical and long-term clinical results of transjugularintrahepatic portosystemic shunts (TIPS) in children with portal hypertension and biliary atresia (BA). Methods: Nine children with BA and recurrent bleeding from esophagogastric and/or intestinal varices were treated by TIPS at the age of 34-156 months and followed-up in two centers. Different types of stents were used. Results: Shunt insertion succeeded in all patients, but in two a second procedure was necessary. Seven procedures lasted more than 3 hr, mainly due to difficult portal vein puncture.Variceal bleeding ceased in all patients; however, 16 reinterventions were performed in eight patients for clinical reasons (n =11) and sonographically suspected restenosis (n =5). Four patients underwent successful liver transplantation 4-51 months after TIPS and five are in good clinical conditions 64-75 months after TIPS. Conclusions: TIPS in children with BA is technically difficult, mainly due to periportal fibrosis and small portal veins. Frequency of reinterventions seems to be higher compared with adults

  18. Effect of amusement park rides on programmable shunt valve settings.

    Science.gov (United States)

    Strahle, Jennifer; Collins, Kelly; Stetler, William R; Smith, Brandon W; Garton, Thomas; Garton, Catherine; Garton, Hugh J L; Maher, Cormac O

    2013-01-01

    Magnetically programmable shunt valves are susceptible to environmental factors including magnetic fields and accelerative forces. It is unknown if rollercoasters with or without magnetic brakes or linear induction motors (LIMs) are capable of altering the setting of a programmable shunt valve. Two different valve types (type A, n = 10; type B, n = 9) were tested at varying resistance settings in 2 trials on 6 different amusement park rides including 2 rides with LIMs, 2 rides with magnetic brakes, and 2 rides without magnetic technology. The performance level of valve type A and the setting of valve type B changed on rollercoasters with magnets (A = 2.5% [2/80]; B = 5.6% [4/72]) and without magnets (A = 7.5% [3/40]; B = 2.8% [1/36]). Neither valve setting changed when exposed to a Ferris wheel or during ambulation throughout the park. Magnetically programmable valves are susceptible to changes in pressure settings when exposed to amusement park rides with elevated vertical gravitational forces, irrespective of the presence of LIMs or magnetic brakes. © 2013 S. Karger AG, Basel.

  19. Transjugular Intrahepatic Portosystemic Shunt (TIPS): Current Status and Future Possibilities

    International Nuclear Information System (INIS)

    Bilbao, Jose Ignacio; Quiroga, Jorge; Herrero, Jose Ignacio; Benito, Alberto

    2002-01-01

    Since the insertion of the first TIPS in 1989 much has been learned about this therapeutic procedure. It has an established role for the treatment of some complications of portal hypertension: prevention of recurrent variceal bleeding and rescue of patients with acute uncontrollable variceal bleeding. In addition TIPS is useful for Budd-Chiari syndrome, refractory ascites and hepatorenal syndrome, although its specific role in these indications remains to be definitively established. However, the decrease in sinusoidal blood flow induced by TIPS can lead to the patient developing hepatic encephalopathy and liver failure in some cases. Therefore, TIPS should be used with caution in patients with very poor liver function. From a technical point of view, successful placement of TIPS is achieved in more than 98% of cases by experienced groups. At present, evaluation of TIPS dysfunction based on morphology probably leads to an overdiagnosis of this complication since most of these cases are not associated with clinical manifestations (recurrent bleeding or refractory ascites). The major disadvantage of TIPS remains its poor long-term patency requiring a mandatory surveillance program. The indicator for shunt function/malfunction should be the portosystemic pressure gradient, which is best assessed by intravascular measurements. Shunt obstructions may be prevented or reduced by the use of stent-grafts in the future

  20. A Bidirectional Relationship between Conceptual Organization and Word Learning

    Directory of Open Access Journals (Sweden)

    Tanya Kaefer

    2013-01-01

    Full Text Available This study explores the relationship between word learning and conceptual organization for preschool-aged children. We proposed a bidirectional model in which increases in word learning lead to increases in taxonomic organization, which, in turn, leads to further increases in word learning. In order to examine this model, we recruited 104 4-year olds from Head Start classrooms; 52 children participated in a two-week training program, and 52 children were in a control group. Results indicated that children in the training program learned more words and were more likely to sort taxonomically than children in the control condition. Furthermore, the number of words learned over the training period predicted the extent to which children categorized taxonomically. Additionally, this ability to categorize taxonomically predicted the number of words learned outside the training program, over and above the number of words learned in the program. These results suggest a bi-directional relationship between conceptual organization and word learning.

  1. Bidirectional selection between two classes in complex social networks.

    Science.gov (United States)

    Zhou, Bin; He, Zhe; Jiang, Luo-Luo; Wang, Nian-Xin; Wang, Bing-Hong

    2014-12-19

    The bidirectional selection between two classes widely emerges in various social lives, such as commercial trading and mate choosing. Until now, the discussions on bidirectional selection in structured human society are quite limited. We demonstrated theoretically that the rate of successfully matching is affected greatly by individuals' neighborhoods in social networks, regardless of the type of networks. Furthermore, it is found that the high average degree of networks contributes to increasing rates of successful matches. The matching performance in different types of networks has been quantitatively investigated, revealing that the small-world networks reinforces the matching rate more than scale-free networks at given average degree. In addition, our analysis is consistent with the modeling result, which provides the theoretical understanding of underlying mechanisms of matching in complex networks.

  2. Bidirectional Barbed Sutures for Wound Closure: Evolution and Applications

    Science.gov (United States)

    Paul, Malcolm D.

    2009-01-01

    Traditionally, wound closure sutures have in common the need to tie knots with the inherent risk of extrusion, palpability, microinfarcts, breakage, and slippage. Bidirectional barbed sutures have barbs arrayed in a helical fashion in opposing directions on either side of an unbarbed midsegment. This suture is inserted at the midpoint of a wound and pulled through till resistance is encountered from the opposing barbs; each half of the suture is then advanced to the lateral ends of the wound. This design provides a method of evenly distributing tension along the incision line, a faster suture placement and closure time with no need to tie knots, and the possibility of improved cosmesis. Bidirectional barbed sutures, which are available in both absorbable and nonabsorbable forms, can be used for simple closures, multilayered closures, and closure of high-tension wounds in a variety of surgical settings. PMID:24527114

  3. Evaluation of complex gonioapparent samples using a bidirectional spectrometer.

    Science.gov (United States)

    Rogelj, Nina; Penttinen, Niko; Gunde, Marta Klanjšek

    2015-08-24

    Many applications use gonioapparent targets whose appearance depends on irradiation and viewing angles; the strongest effects are provided by light diffraction. These targets, optically variable devices (OVDs), are used in both security and authentication applications. This study introduces a bidirectional spectrometer, which enables to analyze samples with most complex angular and spectral properties. In our work, the spectrometer is evaluated with samples having very different types of reflection, concerning spectral and angular distributions. Furthermore, an OVD containing several different grating patches is evaluated. The device uses automatically adjusting exposure time to provide maximum signal dynamics and is capable of doing steps as small as 0.01°. However, even 2° steps for the detector movement showed that this device is more than capable of characterizing even the most complex reflecting surfaces. This study presents sRGB visualizations, discussion of bidirectional reflection, and accurate grating period calculations for all of the grating samples used.

  4. Linearly and nonlinearly bidirectionally coupled synchronization of hyperchaotic systems

    International Nuclear Information System (INIS)

    Zhou Jin; Lu Junan; Wu Xiaoqun

    2007-01-01

    To date, there have been many results about unidirectionally coupled synchronization of chaotic systems. However, much less work is reported on bidirectionally-coupled synchronization. In this paper, we investigate the synchronization of two bidirectionally coupled Chen hyperchaotic systems, which are coupled linearly and nonlinearly respectively. Firstly, linearly coupled synchronization of two hyperchaotic Chen systems is investigated, and a theorem on how to choose the coupling coefficients are developed to guarantee the global asymptotical synchronization of two coupled hyperchaotic systems. Analysis shows that the choice of the coupling coefficients relies on the bound of the chaotic system. Secondly, the nonlinearly coupled synchronization is studied; a sufficient condition for the locally asymptotical synchronization is derived, which is independent of the bound of the hyperchaotic system. Finally, numerical simulations are included to verify the effectiveness and feasibility of the developed theorems

  5. Personalized recommendation based on preferential bidirectional mass diffusion

    Science.gov (United States)

    Chen, Guilin; Gao, Tianrun; Zhu, Xuzhen; Tian, Hui; Yang, Zhao

    2017-03-01

    Recommendation system provides a promising way to alleviate the dilemma of information overload. In physical dynamics, mass diffusion has been used to design effective recommendation algorithms on bipartite network. However, most of the previous studies focus overwhelmingly on unidirectional mass diffusion from collected objects to uncollected objects, while overlooking the opposite direction, leading to the risk of similarity estimation deviation and performance degradation. In addition, they are biased towards recommending popular objects which will not necessarily promote the accuracy but make the recommendation lack diversity and novelty that indeed contribute to the vitality of the system. To overcome the aforementioned disadvantages, we propose a preferential bidirectional mass diffusion (PBMD) algorithm by penalizing the weight of popular objects in bidirectional diffusion. Experiments are evaluated on three benchmark datasets (Movielens, Netflix and Amazon) by 10-fold cross validation, and results indicate that PBMD remarkably outperforms the mainstream methods in accuracy, diversity and novelty.

  6. Optimization Control of Bidirectional Cascaded DC-AC Converter Systems

    DEFF Research Database (Denmark)

    Tian, Yanjun

    in bidirectional cascaded converter. This research work analyses the control strategies based on the topology of dual active bridges converter cascaded with a three phase inverter. It firstly proposed a dc link voltage and active power coordinative control method for this cascaded topology, and it can reduce dc....... The connections of the renewable energy sources to the power system are mostly through the power electronic converters. Moreover, for high controllability and flexibility, power electronic devices are gradually acting as the interface between different networks in power systems, promoting conventional power...... the bidirectional power flow in the distribution level of power systems. Therefore direct contact of converters introduces significant uncertainties to power system, especially for the stability and reliability. This dissertation studies the optimization control of the two stages directly connected converters...

  7. Correcting Bidirectional Effects in Remote Sensing Reflectance from Coastal Waters

    Science.gov (United States)

    Stamnes, K. H.; Fan, Y.; Li, W.; Voss, K. J.; Gatebe, C. K.

    2016-02-01

    Understanding bidirectional effects including sunglint is important for GEO-CAPE for several reasons: (i) correct interpretation of ocean color data; (ii) comparing consistency of spectral radiance data derived from space observations with a single instrument for a variety of illumination and viewing conditions; (iii) merging data collected by different instruments operating simultaneously. We present a new neural network (NN) method to correct bidirectional effects in water-leaving radiance for both Case 1 and Case 2 waters. We also discuss a new BRDF and 2D sun-glint model that was validated by comparing simulated surface reflectances with Cloud Absorption Radiometer (CAR) data. Finally, we present an extension of our marine bio-optical model to the UV range that accounts for the seasonal dependence of the inherent optical properties (IOPs).

  8. Bidirectional pulser made from pulse lines for linear induction accelerators

    International Nuclear Information System (INIS)

    Hotta, E.; Mori, T.; Kobayashi, T.; Okino, A.; Haginomori, E.; Ko, K.C.

    1996-01-01

    In order to obtain high-current charged particle beams, linear induction accelerators (LIA's) of two types have been already constructed. Conventional LIA's adopt a unidirectional pulse injected from an external pulser. The other LIA's, one of which has been proposed and constructed by Pavlovskii et al., have accelerating cavities made from pulse forming lines (PFL's). In this case, no magnetic core loaded in the cavity is necessary. However, the injected pulse must be a bidirectional one. Since a part of the voltage pulse with reversed polarity is used to accelerate a beam, it is possible to make the time integral of the output voltage zero. Thus the final magnetic energy stored in the cavity can be made zero at the end of the pulse, and the pulser-accelerator system attains the energy transfer efficiency of 100%. Accelerators of this type can be divided into two kinds, one of which has cavities with internal energy storage, and the other has cavities with energy injected from external bidirectional pulsers. The accelerator of latter type has been first proposed by Smith, but it has not been realized. Several bidirectional pulsers, which consist of three individual PFL's with arbitrary impedances and a closing switch, are analyzed. Output voltages are analytically calculated by using the method proposed by Dommel for digital computations of electromagnetic transients in networks, and conditions for attaining the maximum efficiency of energy transfer from the pulser to the beam are derived. Thus, 4 bidirectional pulsers of internal energy storage type and 2 of external pulse injection type with energy transfer efficiency of 100% are obtained, including the pulsers already reported by other authors

  9. Bi-directional relationship between pregnancy and periodontal disease.

    Science.gov (United States)

    Armitage, Gary C

    2013-02-01

    During pregnancy profound perturbations in innate and adaptive immunity impact the clinical course of a number of infectious diseases, including those affecting periodontal tissues. Conversely, it has been suggested that periodontal infections may increase the risk of adverse pregnancy outcomes. In this review, a summary of the literature associated with the bidirectional relationship between pregnancy and periodontal disease as well as the possible mechanisms behind this interaction were examined. © 2013 John Wiley & Sons A/S.

  10. Optimized Free Energies from Bidirectional Single-Molecule Force Spectroscopy

    Science.gov (United States)

    Minh, David D. L.; Adib, Artur B.

    2008-05-01

    An optimized method for estimating path-ensemble averages using data from processes driven in opposite directions is presented. Based on this estimator, bidirectional expressions for reconstructing free energies and potentials of mean force from single-molecule force spectroscopy—valid for biasing potentials of arbitrary stiffness—are developed. Numerical simulations on a model potential indicate that these methods perform better than unidirectional strategies.

  11. Aplikasi Bidirectional Assosiatif Memori (BAM) Network pada Pengenalan Model

    OpenAIRE

    Iskandar, Iskhaq

    2001-01-01

    Penelitian ini bertujuan untuk menyusun suatu simulasi komputer yang dapat dipergunakan untuk menguji kemampuan memori komputer dalam mengenali suatu model tertentu berdasarkan algoritma Bidirectional Assosiatif Memori Neural Network. Model yang digunakan dalam penelitian dalam penelitian ini adalah huruf-huruf abjad yang dinyatakan dalam kode polar –1 dan +1 dalam bentuk matrik [5x3]. Hasil yang didapat dalam penelitian ini menunjukkan bahwa rancangan network yang disusun mampu mengenali mod...

  12. Bidirectional Relations between Temperament and Parenting Styles in Chinese Children

    OpenAIRE

    Lee, Erica H.; Zhou, Qing; Eisenberg, Nancy; Wang, Yun

    2012-01-01

    The present study examined bidirectional relations between child temperament and parenting styles in a sample (n = 425) of Chinese children during elementary school period (age range = 6 to 9 years at Wave 1). Using two waves (3.8 years apart) of longitudinal data, we tested two hypotheses: (1) whether child temperament (effortful control and anger/frustration) at Wave 1 predicts parenting styles (authoritative and authoritarian parenting) at Wave 2, controlling for Wave 1 parenting; and (2) ...

  13. An Improved Multidimensional MPA Procedure for Bidirectional Earthquake Excitations

    OpenAIRE

    Wang, Feng; Sun, Jian-Gang; Zhang, Ning

    2014-01-01

    Presently, the modal pushover analysis procedure is extended to multidimensional analysis of structures subjected to multidimensional earthquake excitations. an improved multidimensional modal pushover analysis (IMMPA) method is presented in the paper in order to estimate the response demands of structures subjected to bidirectional earthquake excitations, in which the unidirectional earthquake excitation applied on equivalent SDOF system is replaced by the direct superposition of two compone...

  14. Bi-directional interhemispheric inhibition during unimanual sustained contractions

    Directory of Open Access Journals (Sweden)

    Ni Zhen

    2009-04-01

    Full Text Available Abstract Background The interaction between homologous muscle representations in the right and left primary motor cortex was studied using a paired-pulse transcranial magnetic stimulation (TMS protocol known to evoke interhemispheric inhibition (IHI. The timecourse and magnitude of IHI was studied in fifteen healthy right-handed adults at several interstimulus intervals between the conditioning stimulus and test stimulus (6, 8, 10, 12, 30, 40, 50 ms. IHI was studied in the motor dominant to non-dominant direction and vice versa while the right or left hand was at rest, performing isometric contraction of the first dorsal interosseous (FDI muscle, and isometric contraction of the FDI muscle in the context of holding a pen. Results Compared with rest, IHI was reduced at all ISIs during contraction of either type (with or without the context of pen. IHI was reduced bi-directionally without evidence of hemispheric dominance. Further, contraction of the hand contralateral to the conditioning and test pulse yielded similar reductions in IHI. Conclusion These data provide evidence for bi-directional reduction of IHI during unimanual contractions. During unimanual, sustained contractions of the hand, the contralateral and ipsilateral motor cortices demonstrate reduced inhibition. The data suggest that unimanual movement decreases inhibition bi-directionally across motor hemispheres and offer one explanation for the observation of ipsilateral M1 activity during hand movements.

  15. Bidirectional semantic associations between social power and weight.

    Science.gov (United States)

    He, Xiaoling; Chen, Jun; Li, Jianan

    2018-02-01

    Two experiments were conducted to examine bidirectional semantic associations between power and weight using a priming paradigm. Bidirectionality in the relationship between power and weight was demonstrated, utilising tasks that were identical except that the orders in which the stimuli were presented were reversed. In Experiment 1, an empty scale leaning either leftward or rightward was used as a priming stimulus, and a scale that appeared in equilibrium with a pair of power words was used as a target stimulus. In Experiment 2, a scale with a pair of words that appeared in equilibrium was used as a priming stimulus, and an empty scale leaning either leftward or rightward was used as a target stimulus. We identified interaction effects between power and weight in both experiments. Associations between power and weight provide evidence for both conceptual metaphor views and evolutionary theory. The bidirectionality of metaphorical effects is in line with the strong version of metaphoric structuring. Both language and experiential correlations play important roles in the development of the mapping between power and weight. © 2016 International Union of Psychological Science.

  16. Performance and cavitation characteristics of bi-directional hydrofoils

    Science.gov (United States)

    Nedyalkov, Ivaylo; Wosnik, Martin

    2013-11-01

    Tidal turbines extract energy from flows which reverse direction. One way to address this bi-directionality in horizontal axis turbines that avoid the use of complex and maintenance-intensive yaw or blade pitch mechanisms, is to design bi-directional blades which perform (equally) well in either flow direction. A large number of proposed hydrofoil designs were investigated using numerical simulations. Selected candidate foils were also tested (at various speeds and angles of attack) in the High-Speed Cavitation Tunnel (HICaT) at the University of New Hampshire. Lift and drag were measured using a force balance, and cavitation inception and desinence were recorded. Experimental and numerical results were compared, and the foils were compared to each other and to reference foils. Bi-directional hydrofoils may provide a feasible solution to the problem of reversing flow direction, when their performance and cavitation characteristics are comparable to those for unidirectional foils, and the penalty in decreased energy production is outweighed by the cost reduction due to lower complexity and respectively lower installation and maintenance costs.

  17. Treatment of extrahepatic portal hypertension following a whipple procedure with a Rex shunt: report of a case.

    Science.gov (United States)

    Reichman, Trevor W; Anthony, Tiffany; Testa, Giuliano

    2011-02-01

    The Rex shunt is a mesenteric vein to left portal vein decompressive shunt used for the treatment of portal vein thrombosis and portal hypertension. Its use has been reported primarily in the pediatric population where portal vein thrombosis occurs with some frequency. The shunt is thought to represent a more physiologic shunt, since it restores hepatopedal blood flow through the liver. This report describes the use of this shunt in an adult who had frequent gastrointestinal bleeding secondary to extrahepatic portal vein thrombosis, which occurred as a complication after a pancreaticoduodenectomy.

  18. An in vitro lung model to assess true shunt fraction by multiple inert gas elimination.

    Directory of Open Access Journals (Sweden)

    Balamurugan Varadarajan

    Full Text Available The Multiple Inert Gas Elimination Technique, based on Micropore Membrane Inlet Mass Spectrometry, (MMIMS-MIGET has been designed as a rapid and direct method to assess the full range of ventilation-to-perfusion (V/Q ratios. MMIMS-MIGET distributions have not been assessed in an experimental setup with predefined V/Q-distributions. We aimed (I to construct a novel in vitro lung model (IVLM for the simulation of predefined V/Q distributions with five gas exchange compartments and (II to correlate shunt fractions derived from MMIMS-MIGET with preset reference shunt values of the IVLM. Five hollow-fiber membrane oxygenators switched in parallel within a closed extracorporeal oxygenation circuit were ventilated with sweep gas (V and perfused with human red cell suspension or saline (Q. Inert gas solution was infused into the perfusion circuit of the gas exchange assembly. Sweep gas flow (V was kept constant and reference shunt fractions (IVLM-S were established by bypassing one or more oxygenators with perfusate flow (Q. The derived shunt fractions (MM-S were determined using MIGET by MMIMS from the retention data. Shunt derived by MMIMS-MIGET correlated well with preset reference shunt fractions. The in vitro lung model is a convenient system for the setup of predefined true shunt fractions in validation of MMIMS-MIGET.

  19. Frontal and occipital horn ratio is associated with multifocal intraparenchymal hemorrhages in neonatal shunted hydrocephalus.

    Science.gov (United States)

    Oushy, Soliman; Parker, Jonathon J; Campbell, Kristen; Palmer, Claire; Wilkinson, Corbett; Stence, Nicholas V; Handler, Michael H; Mirsky, David M

    2017-11-01

    OBJECTIVE Placement of a cerebrospinal fluid diversion device (i.e., shunt) is a routine pediatric neurosurgical procedure, often performed in the first weeks of life for treatment of congenital hydrocephalus. In the postoperative period, shunt placement may be complicated by subdural, catheter tract, parenchymal, and intraventricular hemorrhages. The authors observed a subset of infants and neonates who developed multifocal intraparenchymal hemorrhages (MIPH) following shunt placement and sought to determine any predisposing perioperative variables. METHODS A retrospective review of the electronic medical record at a tertiary-care children's hospital was performed for the period 1998-2015. Inclusion criteria consisted of shunt placement, age hydrocephalus. Markers of severity of ventriculomegaly (FOR) and ventricular response to CSF diversion (∆FOR) were significantly associated with occurrence of MIPH. Choice of shunt and etiology of hydrocephalus were also significantly associated with MIPH. After adjusting for corrected age, etiology of hydrocephalus, and shunt setting, the authors found that ∆FOR after shunting was still associated with MIPH. A prospective study of MIPH prevention strategies and assessment of possible implications for patient outcomes is needed.

  20. Controversies: Optic nerve sheath fenestration versus shunt placement for the treatment of idiopathic intracranial hypertension

    Directory of Open Access Journals (Sweden)

    Arielle Spitze

    2014-01-01

    Full Text Available Background: Idiopathic intracranial hypertension (IIH has been increasing in prevalence in the past decade, following the obesity epidemic. When medical treatment fails, surgical treatment options must be considered. However, controversy remains as to which surgical procedure is the preferred surgical option - optic nerve sheath fenestration (ONSF or cerebrospinal fluid (CSF shunting - for the long-term treatment of this syndrome. Purpose: To provide a clinical update of the pros and cons of ONSF versus shunt placement for the treatment of IIH. Design: This was a retrospective review of the current literature in the English language indexed in PubMed. Methods: The authors conducted a PubMed search using the following terms: Idiopathic IIH, pseudotumor cerebri, ONSF, CSF shunts, vetriculo-peritoneal shunting, and lumbo-peritoneal shunting. The authors included pertinent and significant original articles, review articles, and case reports, which revealed the new aspects and updates in these topics. Results: The treatment of IIH remains controversial and lacks randomized controlled clinical trial data. Treatment of IIH rests with the determination of the severity of IIH-related visual loss and headache. Conclusion: The decision for ONSF versus shunting is somewhat institution and surgeon dependent. ONSF is preferred for patients with visual symptoms whereas shunting is reserved for patients with headache. There are positive and negative aspects of both procedures, and a prospective, randomized, controlled trial is needed (currently underway. This article will hopefully be helpful in allowing the reader to make a more informed decision until that time.

  1. A novel method for passing cerebrospinal fluid shunt tubing: a proof of principle study.

    Science.gov (United States)

    Tubbs, R Shane; Goodrich, Dylan; Tubbs, Isaiah; Loukas, Marios; Cohen-Gadol, Aaron A

    2014-12-01

    Few innovations in the method of tunneling shunt tubing for cerebrospinal fluid (CSF) shunt diversion have been made since this treatment of hydrocephalus was first developed. Therefore, this feasibility study was performed with the hope of identifying an improved technique that could potentially carry fewer complications. On 10 cadaver sides and when placed in the supine position, small skin incisions were made at the clavicle and ipsilateral subcostal region, and magnets were used to pass standard shunt tubing between the two incisions. Nickel-plated magnets were less effective in pulling the shunt tubing below the skin compared with ceramic magnets. Of these, magnets with pull strengths of 150-200 lbs were the most effective in dragging the subcutaneous tubing between the two incisions. No obvious damage to the skin from the overlying magnet was seen in any specimen. Few options exist for tunneling distal shunt tubing for CSF shunt procedures. Future patient studies are needed to determine if the technique described herein is superior to current methods, particularly when examining patient groups that are at a greater risk for injury during tunneling shunt catheters.

  2. Numerical and experimental studies of stack shunt current for vanadium redox flow battery

    International Nuclear Information System (INIS)

    Yin, Cong; Guo, Shaoyun; Fang, Honglin; Liu, Jiayi; Li, Yang; Tang, Hao

    2015-01-01

    Highlights: • A coupled three-dimensional model of VRB cell stack is developed. • Shunt current of the stack is studied with the model and experiment. • Increased electrolyte resistance in channel and manifold lowers the shunt current. • Shunt current loss increases with stack cell number nonlinearly. - Abstract: The stack shunt current of VRB (vanadium redox flow battery) was investigated with experiments and 3D (three-dimensional) simulations. In the proposed model, cell voltages and electrolyte conductivities were calculated based on electrochemical reaction distributions and SOC (state of charge) values, respectively, while coulombic loss was estimated according to shunt current and vanadium ionic crossover through membrane. Shunt current distributions and coulombic efficiency are analyzed in terms of electrolyte conductivities and stack cell numbers. The distributions of cell voltages and shunt currents calculated with proposed model are validated with single cell and short stack tests. The model can be used to optimize VRB stack manifold and channel designs to improve VRB system efficiency

  3. Correlation of experimental rCBF determinations in goats with flow measurements from a Doppler-modified carotid artery shunt

    International Nuclear Information System (INIS)

    Loftus, C.M.; Silvidi, J.A.; Becker, J.A.; Miller, B.V.; Bernstein, D.D.

    1989-01-01

    A carotid artery shunt system has been developed that continuously monitors blood flow rates by embedding a Doppler crystal in the shunt wall. The crystal ranges through a liquid lens that enables it to be placed without violation of the shunt lumen. Because the crystal is at a fixed angle (45 degrees) to the axis of blood flow and the diameter of the lumen remains constant, a linear relationship exists between flow rates and the Doppler velocity signal. This shunt system was previously tested in vitro using a pulsatile pump and was found to be accurate to within 4.7% of the actual flow rate. In the present study, animal (goat) experiments were performed consisting of simultaneous carotid shunt flow and bilateral rCBF measurements by the radiolabeled microsphere technique to determine in vivo the accuracy of this Doppler modified shunt and to ascertain the ability of shunt flow to increase in the face of acute contralateral carotid occlusion. Data from five animals show that in vivo shunt flow can be recorded to within 13% of control rCBF and that shunt flow increases nearly 50% under conditions of distal demand (contralateral carotid occlusion). This device may prove useful in laboratory studies of carotid shunt dynamics and in clinical practice to quickly detect correctable shunt flow abnormalities

  4. Continuous monitoring of intracranial pressure after endoscopic third ventriculostomy in the management of CSF shunt failure.

    Science.gov (United States)

    Elgamal, E A

    2010-04-01

    The effectiveness of continuous intracranial pressure (ICP) monitoring in the adaptation period, after endoscopic third ventriculostomy (ETV), and removal of the failed shunt in the management of CSF shunt failure is assessed. Nine patients with active hydrocephalus presenting with CSF shunt obstruction or infection were managed by ETV, removal of the shunt and insertion of an external ventricular drain (EVD) containing an ICP sensor for the purpose of postoperative monitoring of the ICP, and intermittent drainage of CSF. Patient ages ranged from 8 months to 24 years, and six of them were females. Hydrocephalus was obstructive in seven patients, and multiloculated in two. Six patients had an ventriculoperitoneal shunt (VPS), one with a bilateral VPS, one patient had a ventriculoatrial shunt, and one had a VPS and cystoperitoneal shunt (CPS). Shunt failure was caused by obstruction in six patients and infection in three. The post-operative ICP monitoring period ranged from 1-7 days. Intracranial hypertension was persistent in the first day after ETV in 3 patients, and up to 110 mL of CSF were drained to improve its symptoms. ETV was successful in six patients and 3 had permanent VPS. Post-operative continuous ICP monitoring and EVD insertion were very useful in the treatment of CSF shunt failure with ETV. This procedure allowed intermittent CSF drainage, relieving symptoms of elevated ICP, and provided accurate assessment of the success of the ETV and patency of the stoma in the early postoperative days by CT ventriculography and can also be used to install antibiotics in cases of infection.

  5. Staged Transcatheter Treatment of Portal Hypoplasia and Congenital Portosystemic Shunts in Children

    International Nuclear Information System (INIS)

    Bruckheimer, Elchanan; Dagan, Tamir; Atar, Eli; Schwartz, Michael; Kachko, Ludmila; Superina, Riccardo; Amir, Gabriel; Shapiro, Rivka; Birk, Einat

    2013-01-01

    Purpose: Congenital portosystemic shunts (CPSS) with portal venous hypoplasia cause hyperammonemia. Acute shunt closure results in portal hypertension. A transcatheter method of staged shunt reduction to afford growth of portal vessels followed by shunt closure is reported. Methods: Pressure measurements and angiography in the CPSS or superior mesenteric artery (SMA) during temporary occlusion of the shunt were performed. If vessels were diminutive and the pressure was above 18 mmHg, a staged approach was performed, which included implantation of a tailored reducing stent to reduce shunt diameter by ∼50 %. Recatheterization was performed approximately 3 months later. If the portal pressure was below 18 mmHg and vessels had developed, the shunt was closed with a device. Results: Six patients (5 boys, 1 girl) with a median age of 3.3 (range 0.5–13) years had CPSS portal venous hypoplasia and hyperammonemia. Five patients underwent staged closure. One patient tolerated acute closure. One patient required surgical shunt banding because a reducing stent could not be positioned. At median follow-up of 3.8 (range 2.2–8.4) years, a total of 21 procedures (20 transcatheter, 1 surgical) were performed. In all patients, the shunt was closed with a significant reduction in portal pressure (27.7 ± 11.3 to 10.8 ± 1.8 mmHg; p = 0.016), significant growth of the portal vessels (0.8 ± 0.5 to 4.0 ± 2.4 mm; p = 0.037), and normalization of ammonia levels (202.1 ± 53.6 to 65.7 ± 9.6 μmol/L; p = 0.002) with no complications. Conclusion: Staged CPSS closure is effective in causing portal vessel growth and treating hyperammonemia

  6. Impaired arm development after Blalock-Taussig shunts in adults with repaired tetralogy of Fallot.

    Science.gov (United States)

    Le Gloan, Laurianne; Marcotte, François; Leduc, Hugues; Mercier, Lise-Andrée; Dore, Annie; Mongeon, François-Pierre; Ibrahim, Reda; Miro, Joaquim; Asgar, Anita; Poirier, Nancy; Khairy, Paul

    2013-09-30

    Many adults with repaired tetralogy of Fallot have had prior Blalock-Taussig shunts. These shunts may theoretically hinder growth and development of the ipsilateral arm. We prospectively enrolled consecutive patients with tetralogy of Fallot in a cross-sectional study to measure arm length and assess handgrip strength. Bilateral handgrip strength was quantified by a dynamometer in a standing position after instructing patients to clench each hand tightly in succession. The maximum force achieved, in kilograms, was measured. A total of 80 consecutive adults with tetralogy of Fallot, aged 36.0 ± 12.5 years, 49% female, were prospectively enrolled. Thirty-eight (47.5%) patients had prior Blalock-Taussig shunts at a median age of 1.0 year. Twenty-one (55.3%) were left-sided and 23 (60.5%) were classic shunts. All but six patients with right-sided shunts and one without a prior shunt were right-handed. The shunts were present for a median of 4.0 years prior to takedown during corrective surgery. The arm ipsilateral to the shunt was significantly shorter than the contralateral arm (71.5 ± 6.1 versus 73.6 ± 5.6 cm, Ptetralogy of Fallot, Blalock-Taussig shunts may impair normal development of the ipsilateral arm with repercussions in adulthood that include shorter limb length and reduced handgrip strength. These changes are most pronounced in patients with classic end-to-side anastomoses. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  7. Our initial experience with ventriculo-epiplooic shunt in treatment of hydrocephalus in two centers.

    Science.gov (United States)

    Grigorean, Valentin Titus; Sandu, Aurelia Mihaela; Popescu, Mihai; Florian, Ioan Stefan; Lupascu, Cristian Dumitru; Ursulescu, Corina Lupascu

    Hydrocephalus represents impairment in cerebrospinal fluid (CSF) dynamics. If the treatment of hydrocephalus is considered difficult, the repeated revisions of ventriculo-peritoneal (VP) shunts are even more challenging. The aim of this article is to evaluate the efficiency of ventriculo-epiplooic (VEp) shunt as a feasible alternative in hydrocephalic patients. A technical modification regarding the insertion of peritoneal catheter was imagined: midline laparotomy 8-10cm long was performed in order to open the peritoneal cavity; the great omentum was dissected between its two layers; we placed the distal end of the catheter between the two epiplooic layers; a fenestration of 4cm in diameter into the visceral layer was also performed. A retrospective study of medical records of 15 consecutive patients with hydrocephalus treated with VEp shunt is also presented. Between 2008 and 2014 we performed VEp shunt in 15 patients: 5 with congenital hydrocephalus, 8 with secondary hydrocephalus and 2 with normal pressure hydrocephalus. There were 7 men and 8 women. VEp shunt was performed in 13 patients with multiple distal shunt failures and in 2 patients, with history of abdominal surgery, as de novo extracranial drainage procedure. The outcome was favorable in all cases, with no significant postoperative complications. VEp shunt is a new, safe and efficient surgical technique for the treatment of hydrocephalus. VEp shunt is indicated in patients with history of recurrent distal shunt failures, and in patients with history of open abdominal surgery and high risk for developing abdominal complications. Copyright © 2017 Polish Neurological Society. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  8. Gravitational shunt units may cause under-drainage in bedridden patients.

    Science.gov (United States)

    Kaestner, S; Kruschat, T; Nitzsche, N; Deinsberger, W

    2009-03-01

    Implantation of a shunt in a hydrocephalic patient still carries a risk of complications such as over-drainage and under-drainage. Gravitational shunt units are especially designed to minimize the problem of over-drainage. Nevertheless, these valves carry a risk of under-drainage. The best choice of valve for a patient is still challenging. The purpose of this survey was to identify in which patients a gravitational shunt valve is liable to lead to under-drainage. Patients with hydrocephalus entered prospectively into a data base were reviewed retrospectively. The patients were treated between January 2006 to the end of Feb 2007 and those experiencing under- or over-drainage were identified. Thirty-five ventriculo-peritoneal shunt systems were implanted in adult patients. The cause of the hydrocephalus was: normal pressure hydrocephalus in 18 patients, post-haemorrhagic following subarachnoid or intracerebral haemorrhage in 11, associated with a tumour in four and followed a head injury in two patients. Three different valves were used: an adjustable shunt valve with gravitational unit (Pro-GAV 0-20/25 in 21 patients), a gravitational shunt valve with fixed opening pressure (GAV 5/30 in nine patients) and an adjustable differential valve (Hakim medos in five patients). Four patients developed severe, valve-related under-drainage. Each had received a gravitational shunt valve and all were bedridden. In two of these patients it was necessary to change the valve. One patient who had received a differential valve, after regaining mobility developed severe over-drainage with bilateral subdural haematomas. Over-drainage was not seen in long-term bedridden patients with a differential shunt valve. If a bedridden patient with a gravitational shunt valve system lies with a slightly elevated head, this leads to activation of the gravitational unit and this may cause under drainage. As a result, we advise not using an anti-siphon devices in a patient who is bedridden for a

  9. Renal Arteriovenous Shunts: Clinical Features, Imaging Appearance, and Transcatheter Embolization Based on Angioarchitecture.

    Science.gov (United States)

    Maruno, Miyuki; Kiyosue, Hiro; Tanoue, Shuichi; Hongo, Norio; Matsumoto, Shunro; Mori, Hiromu; Sagara, Yoshiko; Kashiwagi, Junji

    2016-01-01

    Renal arteriovenous (AV) shunt, a rare pathologic condition, is divided into two categories, traumatic and nontraumatic, and can cause massive hematuria, retroperitoneal hemorrhage, pain, and high-output heart failure. Although transcatheter embolization is a less-invasive and effective treatment option, it has a potential risk of complications, including renal infarction and pulmonary embolism, and a potential risk of recanalization. The successful embolization of renal AV shunt requires a complete occlusion of the shunted vessel while preventing the migration of embolic materials and preserving normal renal arterial branches, which depends on the selection of adequate techniques and embolic materials for individual cases, based on the etiology and imaging angioarchitecture of the renal AV shunts. A classification of AV malformations in the extremities and body trunk could precisely correspond with the angioarchitecture of the nontraumatic renal AV shunts. The selection of techniques and choice of adequate embolic materials such as coils, vascular plugs, and liquid materials are determined on the basis of cause (eg, traumatic vs nontraumatic), the classification, and some other aspects of the angioarchitecture of renal AV shunts, including the flow and size of the fistulas, multiplicity of the feeders, and endovascular accessibility to the target lesions. Computed tomographic angiography and selective digital subtraction angiography can provide precise information about the angioarchitecture of renal AV shunts before treatment. Color Doppler ultrasonography and time-resolved three-dimensional contrast-enhanced magnetic resonance angiography represent useful tools for screening and follow-up examinations of renal AV shunts after embolization. In this article, the classifications, imaging features, and an endovascular treatment strategy based on the angioarchitecture of renal AV shunts are described. (©)RSNA, 2016.

  10. Staged Transcatheter Treatment of Portal Hypoplasia and Congenital Portosystemic Shunts in Children

    Energy Technology Data Exchange (ETDEWEB)

    Bruckheimer, Elchanan, E-mail: elchananb@bezeqint.net; Dagan, Tamir [Schneider Children' s Medical Center Israel, Section of Pediatric Cardiology (Israel); Atar, Eli; Schwartz, Michael [Schneider Children' s Medical Center Israel, Section of Radiology (Israel); Kachko, Ludmila [Schneider Children' s Medical Center Israel, Section of Anesthesiology (Israel); Superina, Riccardo; Amir, Gabriel [Schneider Children' s Medical Center Israel, Section of Pediatric Cardiology (Israel); Shapiro, Rivka [Schneider Children' s Medical Center Israel, Section of Gastroenterology (Israel); Birk, Einat [Schneider Children' s Medical Center Israel, Section of Pediatric Cardiology (Israel)

    2013-12-15

    Purpose: Congenital portosystemic shunts (CPSS) with portal venous hypoplasia cause hyperammonemia. Acute shunt closure results in portal hypertension. A transcatheter method of staged shunt reduction to afford growth of portal vessels followed by shunt closure is reported. Methods: Pressure measurements and angiography in the CPSS or superior mesenteric artery (SMA) during temporary occlusion of the shunt were performed. If vessels were diminutive and the pressure was above 18 mmHg, a staged approach was performed, which included implantation of a tailored reducing stent to reduce shunt diameter by {approx}50 %. Recatheterization was performed approximately 3 months later. If the portal pressure was below 18 mmHg and vessels had developed, the shunt was closed with a device. Results: Six patients (5 boys, 1 girl) with a median age of 3.3 (range 0.5-13) years had CPSS portal venous hypoplasia and hyperammonemia. Five patients underwent staged closure. One patient tolerated acute closure. One patient required surgical shunt banding because a reducing stent could not be positioned. At median follow-up of 3.8 (range 2.2-8.4) years, a total of 21 procedures (20 transcatheter, 1 surgical) were performed. In all patients, the shunt was closed with a significant reduction in portal pressure (27.7 {+-} 11.3 to 10.8 {+-} 1.8 mmHg; p = 0.016), significant growth of the portal vessels (0.8 {+-} 0.5 to 4.0 {+-} 2.4 mm; p = 0.037), and normalization of ammonia levels (202.1 {+-} 53.6 to 65.7 {+-} 9.6 {mu}mol/L; p = 0.002) with no complications. Conclusion: Staged CPSS closure is effective in causing portal vessel growth and treating hyperammonemia.

  11. Percutaneous Transjugular Direct Porto-caval Shunt in Patients with Budd-Chiari Syndrome

    International Nuclear Information System (INIS)

    Quateen, A.; Pech, M.; Berg, T.; Bergk, A.; Podrabsky, P.; Felix, R.; Ricke, J.

    2006-01-01

    The purpose of the study was to evaluate the feasibility and effectiveness of direct porto-caval shunts in patients with Budd-Chiari syndrome (BCS) in whom there is no access to the hepatic veins during transjugular intrahepatic portosystemic shunt (TIPSS). We included six consecutive patients with fulminant/acute Budd-Chiari syndrome (mean age: 35 years) in whom a conventional TIPSS was not possible due to inaccessible hepatic veins. We performed a direct porto-caval shunt via a transhepatic approach. Patients were followed up by means of clinical examination, laboratory investigations, and Doppler ultrasound. TIPSS implantation from the inferior vena cava (IVC) was successful in all six patients (100%). The median transhepatic shunt length was 9 cm (8-10 cm). No procedure-related complications were observed in our patients. Early shunt occlusion occurred in three out of six patients (50%). In all three of these patients, the stent used to stabilize the shunt ended 1-2 cm before reaching the IVC. All occlusions were successfully recanalized. One of these patients developed recurrent early shunt as well as mesenteric and splenic vein occlusions. She died 7 days after TIPSS placement due to an unmanageable coagulation disorder. The remaining five patients were followed up by planned clinical examination and laboratory investigations (mean follow-up time was 15 months; patient 1 was followed up for 13 months, patient 2 for 14 months, patient 3 for 15 months, and patients 4 and 5 for 16 months) and all displayed a complete and durable resolution of liver failure and ascites without reintervention. In patients with acute liver failure originating from BCS and inaccessible hepatic veins, a direct transhepatic porto-caval shunt can be performed safely and effectively under ultrasound guidance. Future studies in larger patient groups should investigate if the patency of transcaval TIPSS with long transhepatic shunt segments is similar compared to conventional TIPSS via

  12. Developmental intrahepatic shunts of childhood: radiological features and management

    International Nuclear Information System (INIS)

    Paley, M.R.; Farrant, P.; Kane, P.; Karani, J.B.; Heaton, N.D.; Howard, E.R.

    1997-01-01

    The purpose of this study was to evaluate the role of radiological techniques in the diagnosis and management of developmental intrahepatic shunts. Hepatic vascular fistulae are recognised sequelae of liver trauma and intrahepatic tumours. However, there are rare developmental malformations which may present in childhood or later life and which may carry life-threatening complications. Retrospective analysis of clinical and radiological data was carried out in 24 patients. Anomalies evaluated were: (a) direct communication between hepatic artery and hepatic veins; (b) congenital hepatoportal arteriovenous malformations; and (c) congenital portocaval anastomosis with persistent flow through the ductus venosus. Although rare, the prompt recognition of these vascular anomalies allows early surgical or radiological intervention and reversal of the haemodynamic complications. (orig.)

  13. Developmental intrahepatic shunts of childhood: radiological features and management

    Energy Technology Data Exchange (ETDEWEB)

    Paley, M.R.; Farrant, P.; Kane, P.; Karani, J.B. [Department of Radiology, King`s College Hospital, Denmark Hill, London SE5 9RS (United Kingdom); Heaton, N.D.; Howard, E.R. [Department of Paediatric Hepatobiliary Surgery, King`s College Hospital Denmark Hill, London SE5 9RS (United Kingdom)

    1997-12-01

    The purpose of this study was to evaluate the role of radiological techniques in the diagnosis and management of developmental intrahepatic shunts. Hepatic vascular fistulae are recognised sequelae of liver trauma and intrahepatic tumours. However, there are rare developmental malformations which may present in childhood or later life and which may carry life-threatening complications. Retrospective analysis of clinical and radiological data was carried out in 24 patients. Anomalies evaluated were: (a) direct communication between hepatic artery and hepatic veins; (b) congenital hepatoportal arteriovenous malformations; and (c) congenital portocaval anastomosis with persistent flow through the ductus venosus. Although rare, the prompt recognition of these vascular anomalies allows early surgical or radiological intervention and reversal of the haemodynamic complications. (orig.) With 7 figs., 4 tabs., 22 refs.

  14. Analysis of new actuation methods for capacitive shunt micro switchs

    Directory of Open Access Journals (Sweden)

    Ben Sassi S

    2016-01-01

    Full Text Available This work investigates the use of new actuation methods in capacitive shunt micro switches. We formulate the coupled electromechanical problem by taking into account the fringing effects and nonlinearities due to mid-plane stretching. Static analysis is undertaken using the Differential Quadrature Method (DQM to obtain the pull in voltage which is verified by means of the Finite Element Method (FEM. Based on Galerkin approximation, a single degree of freedom dynamic model is developed and limit-cycle solutions are calculated using the Finite Difference Method (FDM. In addition to the harmonic waveform signal, we apply novel actuation waveform signals to simulate the frequency-response. We show that, biased signals, using a square wave signal reduces significantly the pull-in voltage compared to the triangular and harmonic signal . Finally, these results are validated experimentally.

  15. CT-control of the H-graft interposition mesocaval shunt patency

    Energy Technology Data Exchange (ETDEWEB)

    Partanen, P L.K.; Oksala, I

    1984-02-01

    A method for assessing the patency of the H-graft interposition mesocaval shunts by computerized tomography is described. Five patients with such shunts were examined with a 5.5 second CT scanner. After locating the graft a 50 cc bolus of 76% diatrizoate was injected into a cubital vein and 3-4 scans were executed at a preselected level. A distinct vessel like enhancement appeared if the shunt was open. With dynamic CT-scanning the flow can be demonstrated in graphical form as time-density curves.

  16. Intrahepatic Portosystemic Venous Shunt: Successful Embolization Using the Amplatzer Vascular Plug II

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Ju; Shin, Byung Seok; Lee, In Ho; Ohm, Joon Young; Lee, Byung Seok; Ahn, Moon Sang [Chungnam National University Hospital, Chungnam National University College of Medicine, Daejeon (Korea, Republic of); Kim, Ho Jun [Dept. of Radiology, Konyang University Hospital, Konyang University College of Medicine, Daejeon (Korea, Republic of)

    2012-11-15

    A 67-year-old woman presented with memory impairment and behavioral changes. Brain MRI indicated hepatic encephalopathy. Abdominal CT scans revealed an intrahepatic portosystemic venous shunt that consisted of two shunt tracts to the aneurysmal sac that communicated directly with the right hepatic vein. The large tract was successfully occluded by embolization using the newly available AMPLATZERTM Vascular Plug II and the small tract was occluded by using coils. The patient's symptoms disappeared after shunt closure and she remained free of recurrence at the 3-month follow-up evaluation.

  17. Detection of intracardiac shunts with contrast-enhanced dynamic MR imaging

    International Nuclear Information System (INIS)

    Manning, W.J.; Atkinson, D.J.; Parker, J.A.; Edelman, R.R.

    1990-01-01

    This paper reports on ultrafast MR imaging with bolus administration of Gd-DTPA used to detect intracardiac shunts. Ten patients who had recently undergone cardiac catheterization or first-pass radionuclide evaluation were selected for study. These included five patients without intracardiac shunts and five patients with shunts (three with atrial septal defect, two with ventricular septal defect). Resting four-chamber cardiac images were obtained during intravenous injection of Gd-DTPA (0.02 mmol/kg) with an ultrafast, T1-weighted sequence. Images were acquired over 380 msec, with repetitive images obtained with each QRS for 50 beats. In addition, standard MR cine examinations were performed

  18. Congenital hepatic arteriovenous fistula with intrahepatic portosystemic shunt and aortic stenosis in a dog

    International Nuclear Information System (INIS)

    Koide, K.; Koide, Y.; Wada, Y.; Nakaniwa, S.; Yamane, Y.

    2004-01-01

    Examination of a 2-month-old male golden retriever presented to the hospital revealed malnutrition, ascites, cardiac murmur and hyperammonemia. Identification of subaortic stenosis and hepatic arteriovenous fistula was made through ultrasonography and angiocardiography. In addition, intrasurgical mesenteric portography showed an intrahepatic portosystemic shunt. The dog did not show portal hypertension and secondary multiple extrahepatic portosystemic shunts. Surgical correction was attempted after medical treatment. The hepatic artery branch which was connected to the hepatic arteriovenous fistula was separated, and completely ligated using silk ligature. However, the separation of the intrahepatic shunt blood vessel was unsuccessful and the dog died 15 hr postoperatively

  19. Tunable elastic parity-time symmetric structure based on the shunted piezoelectric materials

    Science.gov (United States)

    Hou, Zhilin; Assouar, Badreddine

    2018-02-01

    We theoretically and numerically report on the tunable elastic Parity-Time (PT) symmetric structure based on shunted piezoelectric units. We show that the elastic loss and gain can be archived in piezoelectric materials when they are shunted by external circuits containing positive and negative resistances. We present and discuss, as an example, the strongly dependent relationship between the exceptional points of a three-layered system and the impedance of their external shunted circuit. The achieved results evidence that the PT symmetric structures based on this proposed concept can actively be tuned without any change of their geometric configurations.

  20. Two-port laparoscopic management of a giant pseudocyst complicating ventriculoperitoneal shunt

    Directory of Open Access Journals (Sweden)

    Sandesh V Parelkar

    2014-01-01

    Full Text Available Insertion of a ventriculo-peritoneal (VP shunt is the most common operative procedure for the treatment of hydrocephalus in children. Of the several causes of shunt malfunction, cerebrospinal fluid (CSF pseudocyst is relatively uncommon. There are several modalities to treat a CSF pseudocyst. Laparotomy is required, at times, more than once. We managed a patient of CSF pseudocyst with two-port laparoscopy, by deroofing the psuedocyst and repositioning of the shunt. This minimally invasive technique avoids morbidity associated with laparotomy and aids in early recovery.

  1. Brain abscesses associated with right-to-left shunts in adults.

    Science.gov (United States)

    Memon, Kashif A; Cleveland, Kerry O; Gelfand, Michael S

    2012-04-01

    Although brain abscesses are frequently cryptogenic in origin, bacteria must reach the brain either by direct or hematogenous spread. Right-to-left shunts, caused either by intrapulmonary vascular malformations or congenital heart defects, may allow microorganisms to evade the normal host defenses in the lungs and lead to development of brain abscesses. Two patients recently presented with brain abscesses and were found to have conditions associated with right-to-left shunts. The diagnosis of brain abscess should prompt the clinician to consider right-to-left shunts as a possible predisposing condition for brain abscess.

  2. Scrotal migration of ventriculoperitoneal shunt: a case report at Haji Adam Malik hospital, Medan

    Science.gov (United States)

    Dharmajaya, R.

    2018-03-01

    Ventriculoperitoneal (VP) shunting is one of the most common pediatric neurosurgery operations performed for dealing with hydrocephalus. We report an unusual case of a 1-year-old child with communicating hydrocephalus, who experienced right scrotum swelling after 11 months of shunting. Abdominal x-ray showed the shunt tubing, which was kinked in its distal portion of thescrotum. Ultrasound examination was performed, revealing hydrocele along with the presence of thedistal catheter in the scrotum. The patient underwent distal catheter trimming via laparoscopic approach with general surgery and managed with asuccessful outcome. Prompt surgical management of catheter repositioning is recommended to avoid the risk of further complications.

  3. Severe Juxtahepatic Venous Injury: Survival after Prolonged Hepatic Vascular Isolation Without Shunting

    Directory of Open Access Journals (Sweden)

    J. E. J. Krige

    1990-01-01

    Full Text Available Survival following major juxtahepatic venous injury is rare in blunt liver trauma despite the use of intracaval shunting. Prolonged liver arterial inflow control, total hepatic venous isolation and lobectomy without shunting was used in a patient to repair a combined vena caval and hepatic venous injury after blunt liver injury. An extended period of normothermic hepatic ischemia was tolerated. Early recognition of retrohepatic venous injury and temporary liver packing to control bleeding and correct hypovolemia are essential before caval occlusion. Hepatic vascular isolation without shunting is an effective simple alternative technique allowing major venous repair in complex liver trauma.

  4. The design and implementation of on-line monitoring system for UHV compact shunt capacitors

    Science.gov (United States)

    Tao, Weiliang; Ni, Xuefeng; Lin, Hao; Jiang, Shengbao

    2017-08-01

    Because of the large capacity and compact structure of the UHV compact shunt capacitor, it is difficult to take effective measures to detect and prevent the faults. If the fault capacitor fails to take timely maintenance, it will pose a threat to the safe operation of the system and the life safety of the maintenance personnel. The development of UHV compact shunt capacitor on-line monitoring system can detect and record the on-line operation information of UHV compact shunt capacitors, analyze and evaluate the early fault warning signs, find out the fault capacitor or the capacitor with fault symptom, to ensure safe and reliable operation of the system.

  5. Shunt occlusion for portosystemic shunt syndrome related refractory hepatic encephalopathy-A single-center experience in 21 patients from Kerala.

    Science.gov (United States)

    Philips, Cyriac Abby; Kumar, Lijesh; Augustine, Philip

    2017-09-01

    Large spontaneous portosystemic shunts (SPSS) are seen in a subset of patients with liver disease and medically refractory recurrent/persistent hepatic encephalopathy (MRHE). Shunt occlusion has been shown to improve clinical outcomes. We retrospectively analyzed patient characteristics, SPSS attributes, procedural features, baseline clinical and investigational parameters, neurological outcomes, adverse effects (procedure and portal hypertension related), and risk factors predicting outcomes in liver disease patients undergoing shunt occlusion procedure for MRHE. Between October 2016 and July 2017, 21 patients (Child-Pugh score, CTP 6 to 13) with mean model of end-stage liver disease (MELD) and MELD-sodium scores 15.7 and 19.3 respectively with MRHE [3-cirrhotic Parkinsonism (CP)] were diagnosed to have single or multiple large SPSSs. A total of 29 shunts were occluded (1 surgical, 20 non-surgical). Recurrent and persistent HE and CP markedly improved in the short (n=20, 1 to 3 months), intermediate (n=12, 3 to 6 months), and long (n=7, 6 to 9 months) follow up. None had spontaneous or persistent HE at a median follow up 105 (30 to 329) days (p11 predicted mortality post shunt occlusion (p=0.04). Embolization of large SPSS in liver disease patients with MRHE and modestly preserved liver function is safe and efficacious and associated with improved quality of life and can function as a bridge to liver transplantation in accurately selected patients.

  6. Self-oscillating Galvanic Isolated Bidirectional Very High Frequency DC-DC Converter

    DEFF Research Database (Denmark)

    Pedersen, Jeppe Arnsdorf; Madsen, Mickey Pierre; Knott, Arnold

    2015-01-01

    This paper describes a galvanic isolated bidirectional Very High Frequency (VHF = 30 MHz - 300MHz) ClassE converter. The reason for increasing the switching frequency is to minimize the passive components in the converter. To make the converter topology bidirectional the rectifier has to be synch......This paper describes a galvanic isolated bidirectional Very High Frequency (VHF = 30 MHz - 300MHz) ClassE converter. The reason for increasing the switching frequency is to minimize the passive components in the converter. To make the converter topology bidirectional the rectifier has...

  7. On uniform resampling and gaze analysis of bidirectional texture functions

    Czech Academy of Sciences Publication Activity Database

    Filip, Jiří; Chantler, M.J.; Haindl, Michal

    2009-01-01

    Roč. 6, č. 3 (2009), s. 1-15 ISSN 1544-3558 R&D Projects: GA MŠk 1M0572; GA ČR GA102/08/0593 Grant - others:EC Marie Curie(BE) 41358 Institutional research plan: CEZ:AV0Z10750506 Keywords : BTF * texture * eye tracking Subject RIV: BD - Theory of Information Impact factor: 1.447, year: 2009 http://library.utia.cas.cz/separaty/2009/RO/haindl-on uniform resampling and gaze analysis of bidirectional texture functions.pdf

  8. Chaos synchronization communication using extremely unsymmetrical bidirectional injections.

    Science.gov (United States)

    Zhang, Wei Li; Pan, Wei; Luo, Bin; Zou, Xi Hua; Wang, Meng Yao; Zhou, Zhi

    2008-02-01

    Chaos synchronization and message transmission between two semiconductor lasers with extremely unsymmetrical bidirectional injections (EUBIs) are discussed. By using EUBIs, synchronization is realized through injection locking. Numerical results show that if the laser subjected to strong injection serves as the receiver, chaos pass filtering (CPF) of the system is similar to that of unidirectional coupled systems. Moreover, if the other laser serves as the receiver, a stronger CPF can be obtained. Finally, we demonstrate that messages can be extracted successfully from either of the two transmission directions of the system.

  9. Bi-Directional DC-DC Converter for PHEV Applications

    Energy Technology Data Exchange (ETDEWEB)

    Abas Goodarzi

    2011-01-31

    Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.

  10. Bidirectional Quantum Secure Direct Communication Network Protocol with Hyperentanglement

    International Nuclear Information System (INIS)

    Gu Bin; Chen Yulin; Huang Yugai; Fang Xia

    2011-01-01

    We propose a bidirectional quantum secure direct communication (QSDC) network protocol with the hyperentanglment in both the spatial-mode ad the polarization degrees of freedom of photon pairs which can in principle be produced with a beta barium borate crystal. The secret message can be encoded on the photon pairs with unitary operations in these two degrees of freedom independently. Compared with other QSDC network protocols, our QSDC network protocol has a higher capacity as each photon pair can carry 4 bits of information. Also, we discuss the security of our QSDC network protocol and its feasibility with current techniques. (general)

  11. High Efficient Bidirectional Battery Converter for residential PV Systems

    DEFF Research Database (Denmark)

    Pham, Cam; Kerekes, Tamas; Teodorescu, Remus

    2012-01-01

    Photovoltaic (PV) installation is suited for the residential environment and the generation pattern follows the distribution of residential power consumption in daylight hours. In the cases of unbalance between generation and demand, the Smart PV with its battery storage can absorb or inject...... the power to balance it. High efficient bidirectional converter for the battery storage is required due high system cost and because the power is processed twice. A 1.5kW prototype is designed and built with CoolMOS and SiC diodes, >;95% efficiency has been obtained with 200 kHz hard switching....

  12. Symmetric reconfigurable capacity assignment in a bidirectional DWDM access network.

    Science.gov (United States)

    Ortega, Beatriz; Mora, José; Puerto, Gustavo; Capmany, José

    2007-12-10

    This paper presents a novel architecture for DWDM bidirectional access networks providing symmetric dynamic capacity allocation for both downlink and uplink signals. A foldback arrayed waveguide grating incorporating an optical switch enables the experimental demonstration of flexible assignment of multiservice capacity. Different analog and digital services, such as CATV, 10 GHz-tone, 155Mb/s PRBS and UMTS signals have been transmitted in order to successfully test the system performance under different scenarios of total capacity distribution from the Central Station to different Base Stations with two reconfigurable extra channels for each down and upstream direction.

  13. Bidirectional Texture Function Modeling: State of the Art Survey

    Czech Academy of Sciences Publication Activity Database

    Filip, Jiří; Haindl, Michal

    2009-01-01

    Roč. 31, č. 11 (2009), s. 1921-1940 ISSN 0162-8828 R&D Projects: GA MŠk 1M0572; GA ČR GA102/08/0593; GA AV ČR 1ET400750407 Grant - others:EC Marie Curie(BE) 41358; GA MŠk(CZ) 2C06019 Institutional research plan: CEZ:AV0Z10750506 Keywords : BTF * surface texture * 3D texture Subject RIV: BD - Theory of Information Impact factor: 4.378, year: 2009 http://library.utia.cas.cz/separaty/2009/RO/filip-bidirectional texture function modeling state of the art survey.pdf

  14. Periodic bidirectional associative memory neural networks with distributed delays

    Science.gov (United States)

    Chen, Anping; Huang, Lihong; Liu, Zhigang; Cao, Jinde

    2006-05-01

    Some sufficient conditions are obtained for the existence and global exponential stability of a periodic solution to the general bidirectional associative memory (BAM) neural networks with distributed delays by using the continuation theorem of Mawhin's coincidence degree theory and the Lyapunov functional method and the Young's inequality technique. These results are helpful for designing a globally exponentially stable and periodic oscillatory BAM neural network, and the conditions can be easily verified and be applied in practice. An example is also given to illustrate our results.

  15. Comparison of the bidirectional reflectance distribution function of various surfaces

    International Nuclear Information System (INIS)

    Fernandez, R.; Seasholtz, R.G.; Oberle, L.G.; Kadambi, J.R.

    1989-01-01

    This paper describes the development and use of a system to measure the bidirectional reflectance distribution function (BRDF) of various surfaces. The BRDF measurements are to be used in the analysis and design of optical measurement systems such as laser anemometers. An Ar-ion laser (514 nm) was the light source. Preliminary results are presented for eight samples: two glossy black paints, two flat black paints, black glass, sand-blasted Al, unworked Al, and a white paint. A BaSO4 white reflectance standard was used as the reference sample throughout the tests. 8 refs

  16. Metformin reduces intrahepatic fibrosis and intrapulmonary shunts in biliary cirrhotic rats

    Directory of Open Access Journals (Sweden)

    Mu-Tzu Ko

    2017-08-01

    Conclusion: Metformin reduced liver injury and improved hepatic fibrosis in cirrhotic rats. It also attenuated the intrapulmonary shunts. However, the effects of metformin on pulmonary angiogenesis and hypoxia were insignificant.

  17. [Extracorporeal ventriculoatrial shunt with the use of one-way ball valve].

    Science.gov (United States)

    Kubo, Shigeki; Takimoto, Hiroshi; Hosoi, Kazuki; Toyota, Shingo; Takakura, Shuji; Hayashi, Yasuhiro; Ueno, Masato; Morisako, Toshitaka; Karasawa, Jun; Ninaga, Hideo; Yoshimine, Toshiki

    2002-04-01

    We developed a simple system of an "extracorporeal" ventriculoatrial (VA) shunt using a one-way ball valve (Acty valve II, Kaneka Medix) to release the patient from postoperative constraint during the ventricular drainage. The system is constructed in such a way that the ventricular drainage tube is connected to the central venous catheter via a one-way valve. The CSF is regulated by using the valve and is diverted into the systemic circulation as in the conventional ventriculoatrial shunt. After 2 or 3 weeks of CSF diversion through the extracorporeal VA shunt, a ventriculoperitoneal shunt is placed if hydrocephalus is apparent by temporary occlusion of the system. We applied this system to 4 patients with hydrocephalus, and we found it useful and free from adverse effects. The patient was freed from physical constraint involved in conventional ventricular drainage and an effective program of early rehabilitation was able to be started.

  18. The transjugular portosystemic stent shunt (TIPSS) as an intervention in clinical complication of portal hypertension

    International Nuclear Information System (INIS)

    Thalhammer, A.; Jacobi, V.; Schwarz, W.; Balzer, J.; Abolmaali, N.; Vogl, T.J.

    2001-01-01

    Most frequent complications in patients with liver cirrhosis are due to portal hypertension. Beside ascites circumvent vessles formate with vasodilatation. Due to counterregulation a secondary hyperaldosteronism develops with release of vasocontrictive agents. If conservative and endoscopic methods fail, indication for building a portosystemic shunt is given. The TIPSS procedure is less invasive than the surgical method of Warren-Shunt, so the radiological intervention has replaced surgery. Reducing the portal pressure by the shunt, the clinical complications change for the better. Still problems are defined as hepatic encephalopathy and right ventricular heart failure. Regular follow up investigations have to be performed to detect complications in the shunt. Using regular clinical and radiological check up TIPSS is of clinical benefit with good long term results. (orig.) [de

  19. Bacterial contamination of surgeons' gloves during shunt insertion; a pilot study

    DEFF Research Database (Denmark)

    Sørensen, Preben; Ejlertsen, Tove; Aaen, Dorte

    2008-01-01

    antibiotics and double gloving, by surgeons experienced in shunt surgery. Surgical incision, dissection and tunnelling were done. Then the surgeon, the scrub-nurse and, in three cases, the assistant made an imprint of their outer gloves on agar plates. Hereafter, they changed the outer pair of gloves before...... handling the shunt and completing the operation. The plates were cultured for 6 days in both aerobic and anaerobic environment. In all cases the surgeons gloves were contaminated, and in six cases also the nurses' gloves were contaminated, as well as all three assistants. Propionebacterium acnes were...... nurse and assistant were contaminated with micro-organisms less than 15 min after surgery has been commenced and before the shunts were handled. This study offers a feasible, simple and logical explanation of how shunts may become contaminated and infected. A simple measure would be to change the outer...

  20. Staphylococcus warneri ventriculoperitoneal shunt infection: failure of diagnosis by ventricular CSF sampling.

    Science.gov (United States)

    Martínez-Lage, Juan F; Martínez-Lage Azorín, Laura; Almagro, María-José

    2010-12-01

    The definite diagnosis of hydrocephalus valve infection is generally made by cerebrospinal fluid (CSF) sampling via the valve reservoir, which is considered to be more dependable than that of the CSF obtained by lumbar puncture. We treated a 17-year-old boy with an intra-abdominal pseudocyst due to ventriculoperitoneal shunt infection caused by Staphylococcus warneri whose ventricular CSF, obtained via the valve reservoir, was repeatedly sterile thus causing a considerable delay in the management of the complication. S. warneri constitutes an emergent contaminant of catheters and prostheses. We found only a detailed report of S. warneri infection of a ventriculoatrial shunt. If manifestations of peritoneal involvement in shunted patients would occur, the attention should be shifted to the distal component of the shunt hardware, even in the presence of a normal ventricular CSF as happened in our case to avoid unnecessary delay in diagnosis and management.

  1. Harmonics reduction in standalone DFIG-DC system by shunt active ...

    Indian Academy of Sciences (India)

    Himanshu Misra

    2018-05-22

    May 22, 2018 ... Doubly fed induction generator; standalone; DC voltage regulation; shunt active filter; harmonics ... Operation and design issue of DFIG in DC-net interface is ...... control systems for the operation of DFIGs in wind energy.

  2. Design and test of a novel isolator with negative resistance electromagnetic shunt damping

    International Nuclear Information System (INIS)

    Yan, Bo; Zhang, Xinong; Niu, Hongpan

    2012-01-01

    This paper proposes a negative resistance electromagnetic shunt damping vibration isolator and investigates the effectiveness of the isolator. The isolator consists of a shunt circuit and a pair of electromagnet and permanent magnets that are pasted onto a box-shaped spring. A kind of negative resistance shunt impedance is proposed to cancel the inherent resistance of the electromagnet. The electromechanical coupling coefficient and the electromagnetic damping force calculation formula are obtained by Biot–Savart’s law and Ampère’s law, respectively. A single degree of freedom system is employed to verify the performance of the proposed isolator. The governing equation is established. The performance of the proposed isolator under a half-cycle sine pulse is investigated and discussed. Experiments were carried out and the results agreed well with the numerical predictions. Both the results demonstrate that the negative resistance electromagnetic shunt damping vibration isolator could suppress vibration transmitted to the structure effectively. (paper)

  3. Subdural haematoma complicating shunting for normal pressure hydrocephalus in the setting of concomitant antiplatelet medication

    DEFF Research Database (Denmark)

    Birkeland, Peter; Lauritsen, Jens; Poulsen, Frantz Rom

    2016-01-01

    OBJECTIVE: To report on the occurrence and management of subdural haematoma after shunt implantation for normal pressure hydrocephalus and to determine the risk of recurrence in the setting of antiplatelet medication. METHODS: From a consecutive series of 80 patients implanted with a cerebrospinal...... fluid shunt for normal pressure hydrocephalus, records from 11 patients taking antiplatelet drugs, who subsequently had surgery for subdural haematoma were extracted and retrospectively reviewed. RESULTS: Patients were followed up for a mean of 1819 days after shunt implantation. Subdural haematomas...... reoperations done before the subdural collection disappeared. Only one patient had a late recurrence almost 11 years after shunt implantation. CONCLUSIONS: Subdural haematoma in the setting of a ventriculoperitoneal implantation for normal pressure hydrocephalus and concomitant antiplatelet medication can...

  4. MR imaging of pulsatile CSF movement in hydrocephalus communicans before and after CSF shunt implantation

    International Nuclear Information System (INIS)

    Goldmann, A.; Kunz, U.; Rotermund, F.; Friedrich, J.M.; Schnarkowski, P.

    1992-01-01

    16 patients with hydrocephalus communicans and 5 healthy volunteers were examined to demonstrate the pattern of the pulsatile CSF flow. After implantation of a CSF shunt system the same patients were examined again to show the influence of the shunt on the CSF pulsations. We used a flow-sensitised, cardiac-gated 2D FLASH sequence and analysed the phase and magnitude images. It could be shown that most patients (n=12) had a hyerdynamic pulsatile flow preoperatively. After shunt implantation the pulsatile CSF motion and the clinical symptoms were improved in 8 of these patients. MRI of pulsatile CSF flow movement seems to be a helpful noninvasive tool to estimate the prognosis of a shunt implantation in patients with hydrocephalus communicans. (orig.) [de

  5. Incidence of ischemic lesions by diffusion-weighted imaging after carotid endarterectomy with routine shunt usage

    International Nuclear Information System (INIS)

    Inoue, Tomohiro; Tsutsumi, Kazuo; Adachi, Shinobu; Tanaka, Shota; Yako, Kyoko; Saito, Kuniaki; Kunii, Naoto; Maeda, Keiitirou

    2006-01-01

    Temporary intraluminal shunt was used during 72 consecutive carotid endarterectomies (CEAs) in 61 patients (bilateral CEA in 11 patients) during October 2001 and September 2005. The medical records of these patients were retrospectively reviewed. All procedures were performed with routine shunt insertion without monitoring such as electroencephalography. Pre- and postoperative diffusion-weighted magnetic resonance (MR) imaging was used to detect ischemic complications. Postoperative angiography was performed in 70 cases to detect abnormalities such as major stenosis or dissection of the distal end. Symptomatic ischemic complication occurred in one patient at 1 month. Postoperative diffusion-weighted MR imaging detected new hyperintense lesions in three patients including the symptomatic patient. Postoperative angiography confirmed that the distal end was satisfactory in all cases. The incidence of ischemic lesions of embolic origin after CEA with routine shunt usage is acceptably low if the procedure of shunt device insertion and removal is meticulously conducted. (author)

  6. Optimizing the Shunting Schedule of Electric Multiple Units Depot Using an Enhanced Particle Swarm Optimization Algorithm

    Directory of Open Access Journals (Sweden)

    Jiaxi Wang

    2016-01-01

    Full Text Available The shunting schedule of electric multiple units depot (SSED is one of the essential plans for high-speed train maintenance activities. This paper presents a 0-1 programming model to address the problem of determining an optimal SSED through automatic computing. The objective of the model is to minimize the number of shunting movements and the constraints include track occupation conflicts, shunting routes conflicts, time durations of maintenance processes, and shunting running time. An enhanced particle swarm optimization (EPSO algorithm is proposed to solve the optimization problem. Finally, an empirical study from Shanghai South EMU Depot is carried out to illustrate the model and EPSO algorithm. The optimization results indicate that the proposed method is valid for the SSED problem and that the EPSO algorithm outperforms the traditional PSO algorithm on the aspect of optimality.

  7. Optimizing the Shunting Schedule of Electric Multiple Units Depot Using an Enhanced Particle Swarm Optimization Algorithm

    Science.gov (United States)

    Jin, Junchen

    2016-01-01

    The shunting schedule of electric multiple units depot (SSED) is one of the essential plans for high-speed train maintenance activities. This paper presents a 0-1 programming model to address the problem of determining an optimal SSED through automatic computing. The objective of the model is to minimize the number of shunting movements and the constraints include track occupation conflicts, shunting routes conflicts, time durations of maintenance processes, and shunting running time. An enhanced particle swarm optimization (EPSO) algorithm is proposed to solve the optimization problem. Finally, an empirical study from Shanghai South EMU Depot is carried out to illustrate the model and EPSO algorithm. The optimization results indicate that the proposed method is valid for the SSED problem and that the EPSO algorithm outperforms the traditional PSO algorithm on the aspect of optimality. PMID:27436998

  8. Simulation and Hardware Implementation of Shunt Active Power Filter Based on Synchronous Reference Frame Theory

    Directory of Open Access Journals (Sweden)

    Karthikrjan Senthilnathan

    2018-02-01

    Full Text Available This paper describes about the Hybrid Shunt Active Power Filter (HSAPF for the elimination of the current harmonics in the line side of the three phase three wire systems. The Active Power Filter is based on the Voltage Source Converter (VSC topology. The control strategy for the converter is based on Synchronous Reference Frame (SRF theory. The compensation of harmonics is done by the APF which is connected in the shunt configuration to the system. The Shunt APF has the better compensation of current harmonics. The design and implementation of Shunt active power filter is done by MATLAB/Simulink. The real time implementation by using the ATMEGA 8 Microcontroller. The Simulation and Hardware results shows that the current harmonics are eliminated in the system

  9. Two cases of esophageal cancer with portal hypertension: esophagectomy with venous shunt procedure.

    Science.gov (United States)

    Kato, T; Motohara, T; Kaneko, Y; Shikishima, H; Okushiba, S; Kondo, S; Kato, H

    2001-01-01

    We performed venous shunt procedure in the reconstruction of the esophagus after esophagectomy using the gastric tube in two cases of esophageal cancer with portal hypertension due to liver cirrhosis. In both cases, the short-term postoperative course was uneventful, without congestion in the gastric tube. In Case 1 where the short gastric vein had been used as the shunt vein, the long-term postoperative course was also uneventful, without hepatic encephalopathy or hemorrhage from deterioration of the varices of the gastric tube. However, in Case 2 where the left gastroepiploic vein had been used, hepatic encephalopathy developed due to excessive shunt flow. These results suggested that appropriate shunt flow could be expected by using short gastric vein.

  10. Imaging of the ventriculoperitoneal shunt-related complications in infants and children with hydrocephalus

    International Nuclear Information System (INIS)

    Jeon, Se Ok; Kim, Ji Hye; Oh, Eun Young; Hwang, Hee Young; Lee, Seon Kyu; Lee, Eun Joo; Kwak, Min Sook; Kim, Hyung Sik

    1999-01-01

    To evaluate the frequency and imaging findings of various ventriculo-peritoneal shunt-related complications in pediatric patients with hydrocephalus. We retrospectively reviewed 246 plain radiographs, three shuntograms, 53 ultrasounds, 133 CT scans, and 24 MR images obtained before and after the ventriculo-peritoneal shunt procedure in 33 pediatric patients with hydrocephalus. Using preoperative images, the etiology of the hydrocephalus was assessed. Changes in the size and shape of the ventricles, the location and continuity of shunt apparatus, and the presence of any abnormal enhancement, hemorrhage, edema or tissue loss, or other findings of complications, were analyzed on postoperative images ; the frequency and imaging findings of shunt-related complications such as shunt malfunction, infection, homorrhage or isolated ventricle, and complications caused by overdrainage, were thus evaluated. The frequency of such complications was analyzed according to the etiology of the hydrocephalus, and in addition, medical records were reviewed and correlated with imaging findings. In 18 of the 33 patients(54%), a total of 31 complications was detected. These were present in four of five cases (80%) of hydrocephalus caused by meningitis and ventriculitis, seven of twelve (58%) intraventricular hemorrhage, two of four (50%) unknown cases, three of nine (33%) congenital malformations, one of two (50%) tumors, and one (100%) congenital infection. Shunt malfunction was most common (n=15), and was accompanied by findings of enlarged ventricles, periventricular and peritubal edema, and abnormal location of the shunt tube. Symptoms and signs of increased intracranial pressure were also noted. Subdural hemorrhage and infection were present in four cases each ; findings of infection were enhancement of the ventricular wall, meninges, and parenchyma, as well as sonographically noted intraventricular septation and increased ventricular wall echo. Isolated lateral ventricle (n=4) or 4

  11. Die transkranielle Doppler-Sonographie zur Identifikation von Rechts-Links-Shunts

    OpenAIRE

    Jekentaite, R. (Ruta)

    2003-01-01

    Paradoxe Embolien über einen Rechts-Links-Shunt (RLS) stellen eine Ursache von Hirninfarkten dar. Diese Shunts werden mittels TEE oder TCD diagnostiziert. Ziele dieser Studie waren die Bestimmung des optimalen Timings des Valsalva-Manövers (VM) sowie Vergleich der zwei Kontrastmittel Echovist®-300 und Echovist®-200. 64 Patienten wurden mittels beider Methoden untersucht. Nach der KM-Injektion wurden die Mikroemboliesignale (MES) in der ACM bilateral dopplersonographisch registriert. Die Unt...

  12. Spontaneous expectoration of a Blalock-Taussig shunt a decade after operation

    Directory of Open Access Journals (Sweden)

    Shyam S Kothari

    2015-01-01

    Full Text Available An eleven-year-old boy expectorated a foreign body in cough that was identified as the prosthetic graft used for a Blalock-Taussig shunt. The shunt procedure was done 10 years earlier, and a definitive repair for tetralogy of Fallot was done a year later. He had no other symptoms, and a computed tomography (CT angiogram did not reveal any other significant anomaly. The reason for this extremely rare event is unclear.

  13. Noninvasive measurement of nutrient portal blood shunting: an experimental study with [14C]ursodeoxycholic acid

    International Nuclear Information System (INIS)

    Nordlinger, B.; Parquet, M.; Infante, R.; Moreels, R.; Blondiau, P.; Boschat, M.; Groussard, M.; Huguet, C.

    1982-01-01

    All of the methods proposed for measuring portal blood flow are either invasive, estimate total rather than nutrient flow, and none has proved reliable in cirrhotic patients. A method has been derived from pharmacokinetic principles used for the calculation of bioavailability of drugs according to the route of administration (i.v. or p.o.) and tested experimentally in 20 pigs. A tracer dose of [ 14 C]ursodeoxycholic acid, a biliary acid with a high-liver first-pass effect, is administered in the duodenum, and serial peripheral blood samples are taken. Later, the same dose of the same drug is administered i.v. The shunt fraction of portal blood F is obtained by the ratio of the areas under the plasma level vs. time curves (AUC) after p.o. and i.v. administrations: (see formula in text). The pigs were divided into three experimental groups. (i) Group I: undisturbed portal flow; (ii) Group II: total diversion of portal blood with an end-to-side portacaval shunt, and (iii) Group III: partial diversion of portal blood through a side-to-side portacaval shunt. Portal flow was measured during surgery with an electromagnetic flowmeter above and below the shunt and the degree of shunting calculated. Results show that the shunt fraction measured with ursodeoxycholic acid is well-correlated with hemodynamic data. No overlap between Groups I and III is observed. It is concluded that the shunt fraction of nutrient portal blood can be measured with this noninvasive method. Minute amounts of ursodeoxycholic acid were used in order to be completely metabolized by the liver, even in spite of hepatocellular dysfunction. Therefore, this method should be valid in cirrhotic patients and be useful to decide the type of portasystemic shunt to propose for the decompression of gastroesophageal varices

  14. Transdiaphragmatic Approach to Attenuate Porto-Azygos Shunts Inserting in the Thorax.

    Science.gov (United States)

    Or, Matan; Kitshoff, Adriaan; Devriendt, Nausikaa; De Ridder, Marianne; Quist-Rybachuk, Galena; de Rooster, Hilde

    2016-11-01

    To describe the surgical technique and document the application of a transdiaphragmatic approach to attenuate porto-azygos shunts inserting in the thoracic section of the azygos vein. Cadaveric study and prospective case series. Canine cadavers (n=6) and client-owned dogs with porto-azygos shunts inserting in the thoracic section of the azygos vein (n=9). In the cadavers, the azygos vein was filled with aqueous latex. Landmarks were established for creating a safe transdiaphragmatic approach to the caudal intrathoracic portion of the azygos vein. In the clinical cases, porto-azygos communication was diagnosed by trans-splenic portal scintigraphy. All shunts were attenuated close to their insertion site via ventral midline celiotomy and a transdiaphragmatic approach to the shunt. Perioperative complications were recorded. A 3-5 cm incision, 0.5-1 cm ventral and lateral to the level of the aortic hiatus, was made in the pars lumbalis part of the diaphragm. Stay sutures at both sides of the diaphragmatic incision were placed to open up the incision and a retractor was used to push the esophagus away from the aorta. Intrathoracic insertion of the shunt was confirmed intraoperative. Exposure of the shunt insertion site at the azygos vein was excellent in all clinical cases. No intraoperative or postoperative complications were encountered. If thoracic attenuation of a porto-azygos shunt is considered, a transdiaphragmatic approach exposes the insertion site for shunt attenuation. This approach is straightforward, without unnecessary abdominal organ manipulation, and since attenuates at the insertion, avoids missing additional contributing branches. © Copyright 2016 by The American College of Veterinary Surgeons.

  15. Modified temporary end-to-side portocaval shunt in liver and small bowel transplantation.

    Science.gov (United States)

    Molmenti, E P; Marsh, J W; Molmenti, H; Reyes, J; Fung, J J

    2001-10-01

    Piggyback orthotopic liver transplantation (LTx) has permitted the elimination of extra-corporeal venovenous bypass. In some instances, an internal temporary portocaval shunt has to be constructed in order to prevent hemodynamic instability. We describe a technique in which a donor iliac vein graft is used to bridge the distance between the portal vein and vena cava in cases where a direct shunt cannot be constructed. This technique can be applied to liver Tx as well as to liver and small bowel Tx.

  16. Abnormal Gas Diffusing Capacity and Portosystemic Shunt in Patients With Chronic Liver Disease

    OpenAIRE

    Park, Moon-Seung; Lee, Min-Ho; Park, Yoo-Sin; Kim, Shin-Hee; Kwak, Min-Jung; Kang, Ju-Seop

    2012-01-01

    Background Pulmonary dysfunctions including the hepatopulmonary syndrome and portosystemic shunt are important complications of hepatic cirrhosis. To investigate the severity and nature of abnormal gas diffusing capacity and its correlation to portosystemic shunt in patients with chronic liver disease. Methods Forty-four patients with chronic liver disease (15 chronic active hepatitis (CAH), 16 Child-Pugh class A, and 13 Child-Pugh class B) without other diseases history were enrolled in the ...

  17. Shunts to divert aqueous humor to distant epithelialized cavities after keratoprosthesis surgery.

    Science.gov (United States)

    Dohlman, Claes H; Grosskreutz, Cynthia L; Chen, Teresa C; Pasquale, Louis R; Rubin, Peter A D; Kim, Eva C; Durand, Marlene

    2010-02-01

    Glaucoma is a frequent and often severe problem in patients needing keratoprosthesis (KPro) surgery. Standard glaucoma shunts in these cases often develop a very dense capsule that obstructs flow and causes intraocular pressure elevation. Therefore, we developed shunts that deliver aqueous to distant epithelialized cavities where an obstructing capsule is less likely to form. In this retroactive study of such shunts, the risk of postoperative infection (especially endophthalmitis) has been assessed. Ahmed shunts were connected with a tube to the lacrimal sac or ethmoid sinuses. In subsequent designs the polypropylene plate was eliminated, the valve was enclosed and a distal tube added (New World Medical Inc, Rancho Cucamonga, CA). The latter shunts were connected to the maxillary sinus or lower lid fornix. Between 2001 and 2005 the devices were implanted in 34 patients with very severe ocular disease. (31 had KPro implanted). Thus, the distal tube was led to the lacrimal sac (2 cases), to the ethmoid sinuses (6), to the maxillary sinus (16 cases), and to the lower lid fornix (10 cases). The patients were followed for cumulatively 145 shunt years, with a mean follow-up of 4 years and 3 months. They were instructed to administer low-dose topical antibiotics indefinitely. Only 1 case of acute bacterial endophthalmitis occurred, thus an incidence of 0.7% per shunt year. A slow-growing Mycobacterium was cultured in a disintegrating eye and 1 bacterial maxillary sinusitis occurred, both in autoimmune diseases. Three valves became exposed and had to be removed (1 replaced). Four eyes developed hypotony, probably from valve failure. The shunt arrangement, which connects the anterior chamber to potentially microbe-populated cavities or to the lower lid fornix and its flora, might be suspected to allow rapid retrograde invasion of infective agents, resulting in endophthalmitis. In this series of KPro patients, however, the incidence of severe infection was very low, in fact

  18. Incorporation of distributed generation and shunt capacitor in radial distribution system for techno-economic benefits

    Directory of Open Access Journals (Sweden)

    Mukul Dixit

    2017-04-01

    The various costs such as purchase active power from grid, DG installation, capacitor installation, DG Operation and Maintenance (O&M are evaluated at two different load scenarios. In addition to that, technical and economical analyses are examined for various combinations of DGs and shunt capacitors. The proposed methodology is successfully demonstrated on 33-bus and 85-bus radial networks and the obtained numerical outcomes validate the suitability, importance and effectiveness to identify locations as well as sizes of DGs and shunt capacitors.

  19. Intracranial Pressure-Guided Shunt Valve Adjustments with the Miethke Sensor Reservoir.

    Science.gov (United States)

    Antes, Sebastian; Stadie, Axel; Müller, Simon; Linsler, Stefan; Breuskin, David; Oertel, Joachim

    2018-01-01

    Telemetric intracranial pressure (ICP) monitoring seems to be a promising therapy-supporting option in shunt-treated patients. Benefits become obvious when headaches are unspecific and clinical symptoms cannot be related to possible overdrainage or underdrainage. In this study, we evaluated a new telemetric device to individually adjust shunt valves according to ICP measurements. Between December 2015 and November 2016, 25 patients with suspected suboptimal shunt valve settings underwent insertion of a telemetric ICP sensor (Sensor Reservoir; Christoph Miethke, Potsdam, Germany). Over a 1-year period, a total of 183 telemetric ICP measurements and 85 shunt valve adjustments were carried out. Retrospective statistic analyses focused on valve adjustments, ICP values, and clinical outcomes. ICP-guided valve adjustments positively changed the clinical state in 18 out of 25 patients. Clinical improvement over time was associated with significant changes of the valve settings and ICP values. Interestingly, a therapeutically normalized ICP profile was not automatically associated with clinical improvement. The Sensor Reservoir is an important and valuable tool for shunt-treated patients suffering from drainage-related problems. The possibility to simultaneously recognize and solve shunt problems represents the decisive advantage. Nevertheless, measurements with the Sensor Reservoir did not allow for the determination of default valve settings or universal target ICP values. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Demonstration of arterioportal shunt by dynamic computed tomography and its diagnostic value

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, Takatsune; Hiyama, Yoshiaki; Saitoh, Masayuki

    1983-11-01

    Sixty-one patients, 41 with hepatocellular carcinoma and 20 with liver cirrhosis, were examined by dynamic computed tomography (CT) and all but one with hepatocellular carcinoma were examined by celiac angiography. Dynamic CT disclosed arterioportal shunting in eleven cases of hepatocellular carcinoma and in one of cirrhotics. All of them were confirmed by angiography except one case in which angiography could not be performed. In ten of these eleven cases arterooportal shunt was adjacent to a mass lesion on dynamic CT, suggesting tumor invasion into the portal branch. In one with hepatocellular carcinoma, the shunt was remote from the mass. In one with cirrhosis, there was no mass. In these last two cases, the shunt might have been caused by prior percutaneus needle puncture. In another case of hepatocellular carcinoma, celiac angiography but not CT demonstrated an arterioportal shunt. Thus dynamic CT was nearly as diagnostic as celiac arterigraphy for the demonstration of arterioportal shunt due to portal invasion of hepatocellular carcinoma and percutaneus needle puncture.

  1. Demonstration of arterioportal shunt by dynamic computed tomography and its diagnostic value

    International Nuclear Information System (INIS)

    Nakayama, Takatsune; Hiyama, Yoshiaki; Saitoh, Masayuki

    1983-01-01

    Sixty-one patients, 41 with hepatocellular carcinoma and 20 with liver cirrhosis, were examined by dynamic computed tomography (CT) and all but one with hepatocellular carcinoma were examined by celiac angiography. Dynamic CT disclosed arterioportal shunting in eleven cases of hepatocellular carcinima and in one of cirrhotics. All of them were confirmed by angiography except one case in which angiography could not be performed. In ten of these eleven cases arterioportal shunt was adjacent to a mass lesion on dynamic CT, suggesting tumor invasion into the portal branch. In one with hepatocellular carcinoma, the shunt was remote from the mass. In one with cirrhosis, there was no mass. In these last two cases, the shunt might have been caused by prior percutaneus needle puncture. In another case of hepatocellular carcinoma, celiac angiography but not CT demonstrated an arterioportal shunt. Thus dynamic CT was nearly as diagnostic as celiac arterigraphy for the demonstration of arterioportal shunt due to portal invasion of hepatocellular carcinoma and percutaneus needle puncture. (author)

  2. Broadband transmission noise reduction of smart panels featuring piezoelectric shunt circuits and sound-absorbing material.

    Science.gov (United States)

    Kim, Jaehwan; Lee, Joong-Kuen

    2002-09-01

    The possibility of a broadband noise reduction of piezoelectric smart panels is experimentally studied. A piezoelectric smart panel is basically a plate structure on which piezoelectric patches with electrical shunt circuits are mounted and sound-absorbing material is bonded on the surface of the structure. Sound-absorbing material can absorb the sound transmitted at the midfrequency region effectively while the use of piezoelectric shunt damping can reduce the transmission at resonance frequencies of the panel structure. To be able to reduce the sound transmission at low panel resonance frequencies, piezoelectric damping using the measured electrical impedance model is adopted. A resonant shunt circuit for piezoelectric shunt damping is composed of resistor and inductor in series, and they are determined by maximizing the dissipated energy through the circuit. The transmitted noise-reduction performance of smart panels is tested in an acoustic tunnel. The tunnel is a square cross-sectional tube and a loudspeaker is mounted at one side of the tube as a sound source. Panels are mounted in the middle of the tunnel and the transmitted sound pressure across panels is measured. When an absorbing material is bonded on a single plate, a remarkable transmitted noise reduction in the midfrequency region is observed except for the fundamental resonance frequency of the plate. By enabling the piezoelectric shunt damping, noise reduction is achieved at the resonance frequency as well. Piezoelectric smart panels incorporating passive absorbing material and piezoelectric shunt damping is a promising technology for noise reduction over a broadband of frequencies.

  3. Vaginal Migration of Ventriculoperitoneal Shunt Catheter and Cerebrospinal Fluid Leak as a Complication of Hysterectomy.

    Science.gov (United States)

    Houten, John K; Smith, Shiela; Schwartz, Amit Y

    2017-08-01

    Ventriculoperitoneal (VP) shunting is a common neurosurgical procedure to treat hydrocephalus that diverts cerebrospinal fluid from the cerebral ventricles to the peritoneal cavity for reabsorption. The distal catheter may potentially migrate through any potential or iatrogenic opening in the peritoneal cavity. Increasingly successfully management of childhood hydrocephalus and adult-onset conditions leading to hydrocephalus, such as subarachnoid hemorrhage, is leading many adult female patients harboring VP shunts needing to undergo hysterectomy. Hysterectomy creates a potential defect though which a VP shunt catheter may migrate. It is not known whether the hysterectomy cuff closure technique may affect the likelihood of distal catheter migration though the repair site. We report the case of a 38-year-old woman with a VP shunt who underwent laparoscopic hysterectomy via an open vaginal cuff technique who subsequently presented with vaginal cerebrospinal fluid leakage secondary to migration of the distal shunt catheter through the hysterectomy cuff. Vaginal migration of the distal VP shunt catheter is a possible complication of hysterectomy. The authors postulate that an open cuff hysterectomy closure technique may increase the risk of catheter migration, an issue that may be better understood with further investigation. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Surgical Outcomes of Ahmed or Baerveldt Tube Shunt Implantation for medically Uncontrolled Traumatic Glaucoma.

    Science.gov (United States)

    Yadgarov, Arkadiy; Liu, Dan; Crane, Elliot S; Khouri, Albert S

    2017-01-01

    To describe postoperative surgical success of either Ahmed or Baerveldt tube shunt implantation for eyes with medically uncontrolled traumatic glaucoma. A review was carried out to identify patients with traumatic glaucoma that required tube shunt implantation between 2009 and 2015 at Rutgers University in Newark, New Jersey, USA. Seventeen eyes from 17 patients met inclusion criteria, including at least 3-month postoperative follow-up. The main outcome measure was surgical success at 1-year follow-up after tube implantation. Mean preoperative intraocular pressure (IOP) was 34.1 ± 8.2 mm Hg on 3.1 ± 1.6 ocular hypotensive medications. Nine eyes (53%) sustained closed globe injury. Ten eyes (59%) received an Ahmed valve shunt and seven eyes (41%) received a Baerveldt tube shunt. Surgical success rate at 1 year postoperatively was 83%. Compared to preoperative, the mean postoperative IOP was significantly lower (16.1 ± 3.5 mm Hg, p Ahmed or Baerveldt tube shunt provided successful control of IOP in patients with medically uncontrollable traumatic glaucoma. Yadgarov A, Liu D, Crane ES, Khouri AS. Surgical Outcomes of Ahmed or Baerveldt Tube Shunt Implantation for medically Uncontrolled Traumatic Glaucoma. J Curr Glaucoma Pract 2017;11(1):16-21.

  5. Electron microscopic evaluation of a gold glaucoma micro shunt after explantation.

    Science.gov (United States)

    Berk, Thomas A; Tam, Diamond Y; Werner, Liliana; Mamalis, Nick; Ahmed, Iqbal Ike K

    2015-03-01

    We present a case of an explanted gold glaucoma micro shunt (GMS Plus) and the subsequent light and electron microscopic analyses. The shunt was implanted in a patient with medically refractive glaucoma. The intraocular pressure (IOP) was stable at 12 mm Hg 6 months postoperatively but spiked to 26 mm Hg 6 months later; membranous growth was visible on the implant gonioscopically. A second gold micro shunt was placed 2 years after the first. The IOP was 7 mm Hg 1 week postoperatively but increased to 23 mm Hg 3 weeks later; similar membranous growth was visible on this implant. One of the shunts was explanted, and light and scanning electron microscopic analyses revealed encapsulation around the shunt exterior and connective tissue invasion of the microstructure. This represents the first electron microscopic analysis of an explanted gold glaucoma micro shunt and the first unequivocal images of the fibrotic pseudo-capsule traversing its microchannels and fenestrations. Dr. Ahmed is a consultant to and has received research grants from Solx, Inc. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  6. Morphology of congenital portosystemic shunts involving the left colic vein in dogs and cats.

    Science.gov (United States)

    White, R N; Parry, A T

    2016-05-01

    To describe the anatomy of congenital portosystemic shunts involving the left colic vein in dogs and cats. Retrospective review of a consecutive series of dogs and cats managed for congenital portosystemic shunts. For inclusion a shunt involving the left colic vein with recorded intraoperative mesenteric portovenography or computed tomography angiography along with direct gross surgical observations at the time of surgery was required. Six dogs and three cats met the inclusion criteria. All cases had a shunt which involved a distended left colic vein. The final communication with a systemic vein was variable; in seven cases (five dogs, two cats) it was via the caudal vena cava, in one cat it was via the common iliac vein and in the remaining dog it was via the internal iliac vein. In addition, two cats showed caudal vena cava duplication. The morphology of this shunt type appeared to be a result of an abnormal communication between either the left colic vein or the cranial rectal vein and a pelvic systemic vein (caudal vena cava, common iliac vein or internal iliac vein). This information may help with surgical planning in cases undergoing shunt closure surgery. © 2016 British Small Animal Veterinary Association.

  7. A Study on the Measurement of Intrapulmonary Shunt in Liver Diseases by the Nucleolide Method

    International Nuclear Information System (INIS)

    Yun, Sung Chul; Ahn, Jae Hee; Choi, Soo Bong

    1987-01-01

    The fact there are increase of intrapulmonary arteriovenous shunt amount in the liver cirrhosis patient has been known since 1950. And the method of shunt amount calculation by radionuclide method using 99m Tc-MAA was introduced in the middle of 1970. We measured intrapulmonary shunt amount by means of perfusion lung scan using 99m Tc-MAA in the various type of liver diseases especially in chronic liver diseases and acute liver disease. The results were as followed. 1) The amount of arteriovenous intrapulmonary shunt in the total case of liver disease was 9.3±3.9%, and that of in the control group was 4.6±2.1%. 2) The amount of arteriovenous intrapulmonary shunt in the chronic liver disease was 10.8±4.4%, and that of in the acute liver disease was 7.2±2.8%. We observed significant differences between normal control group and liver disease group, and between chronic liver disease group and acute liver disease group in the amount of shunt by the nucleolide method.

  8. Simulation model of harmonics reduction technique using shunt active filter by cascade multilevel inverter method

    Science.gov (United States)

    Andreh, Angga Muhamad; Subiyanto, Sunardiyo, Said

    2017-01-01

    Development of non-linear loading in the application of industry and distribution system and also harmonic compensation becomes important. Harmonic pollution is an urgent problem in increasing power quality. The main contribution of the study is the modeling approach used to design a shunt active filter and the application of the cascade multilevel inverter topology to improve the power quality of electrical energy. In this study, shunt active filter was aimed to eliminate dominant harmonic component by injecting opposite currents with the harmonic component system. The active filter was designed by shunt configuration with cascaded multilevel inverter method controlled by PID controller and SPWM. With this shunt active filter, the harmonic current can be reduced so that the current wave pattern of the source is approximately sinusoidal. Design and simulation were conducted by using Power Simulator (PSIM) software. Shunt active filter performance experiment was conducted on the IEEE four bus test system. The result of shunt active filter installation on the system (IEEE four bus) could reduce THD current from 28.68% to 3.09%. With this result, the active filter can be applied as an effective method to reduce harmonics.

  9. The Bidirectional Relationship between Diabetes and Depression: A Literature Review.

    Science.gov (United States)

    Alzoubi, Abdallah; Abunaser, Rnad; Khassawneh, Adi; Alfaqih, Mahmoud; Khasawneh, Aws; Abdo, Nour

    2018-05-01

    Diabetes is a major public health problem worldwide. Depression is a serious mental condition that decreases mental and physical functioning and reduces the quality of life. Several lines of evidence suggest a bidirectional relationship between diabetes and depression: diabetes patients are twice as likely to experience depression than nondiabetic individuals. In contrast, depression increases the risk of diabetes and interferes with its daily self-management. Diabetes patients with depression have poor glycemic control, reduced quality of life, and an increased risk of diabetes complications, consequently having an increased mortality rate. Conflicting evidence exists on the potential role of factors that may account for or modulate the relationship between diabetes and depression. Therefore, this review aims to highlight the most notable body of literature that dissects the various facets of the bidirectional relationship between diabetes and depression. A focused discussion of the proposed mechanisms underlying this relationship is also provided. We systematically reviewed the relevant literature in the PubMed database, using the keywords "Diabetes AND Depression". After exclusion of duplicate and irrelevant material, literature eligible for inclusion in this review was based on meta-analysis studies, clinical trials with large sample sizes (n≥1,000), randomized clinical trials, and comprehensive national and cross-country clinical studies. The evidence we present in this review supports the pressing need for long, outcome-oriented, randomized clinical trials to determine whether the identification and treatment of patients with these comorbid conditions will improve their medical outcomes and quality of life.

  10. Bidirectional Relations between Temperament and Parenting Styles in Chinese Children

    Science.gov (United States)

    Lee, Erica H.; Zhou, Qing; Eisenberg, Nancy; Wang, Yun

    2012-01-01

    The present study examined bidirectional relations between child temperament and parenting styles in a sample (n = 425) of Chinese children during elementary school period (age range = 6 to 9 years at Wave 1). Using two waves (3.8 years apart) of longitudinal data, we tested two hypotheses: (1) whether child temperament (effortful control and anger/frustration) at Wave 1 predicts parenting styles (authoritative and authoritarian parenting) at Wave 2, controlling for Wave 1 parenting; and (2) whether parenting styles at Wave 1 predict Wave 2 temperament, controlling for Wave 1 temperament. We found support for bidirectional relations between temperament and authoritarian parenting, such that higher effortful control and lower anger/frustration were associated with higher authoritarian parenting across time and in both directions. There were no significant cross-time associations between children’s temperament and authoritative parenting. These findings extend the previous tests of transactional relations between child temperament and parenting in Chinese children and are consistent with the cultural values toward effortful control and control of anger/frustration in Chinese society. PMID:23482684

  11. The Bidirectional Relationship between Sleep and Immunity against Infections

    Directory of Open Access Journals (Sweden)

    Elizabeth G. Ibarra-Coronado

    2015-01-01

    Full Text Available Sleep is considered an important modulator of the immune response. Thus, a lack of sleep can weaken immunity, increasing organism susceptibility to infection. For instance, shorter sleep durations are associated with a rise in suffering from the common cold. The function of sleep in altering immune responses must be determined to understand how sleep deprivation increases the susceptibility to viral, bacterial, and parasitic infections. There are several explanations for greater susceptibility to infections after reduced sleep, such as impaired mitogenic proliferation of lymphocytes, decreased HLA-DR expression, the upregulation of CD14+, and variations in CD4+ and CD8+ T lymphocytes, which have been observed during partial sleep deprivation. Also, steroid hormones, in addition to regulating sexual behavior, influence sleep. Thus, we hypothesize that sleep and the immune-endocrine system have a bidirectional relationship in governing various physiological processes, including immunity to infections. This review discusses the evidence on the bidirectional effects of the immune response against viral, bacterial, and parasitic infections on sleep patterns and how the lack of sleep affects the immune response against such agents. Because sleep is essential in the maintenance of homeostasis, these situations must be adapted to elicit changes in sleep patterns and other physiological parameters during the immune response to infections to which the organism is continuously exposed.

  12. An Improved Multidimensional MPA Procedure for Bidirectional Earthquake Excitations

    Directory of Open Access Journals (Sweden)

    Feng Wang

    2014-01-01

    Full Text Available Presently, the modal pushover analysis procedure is extended to multidimensional analysis of structures subjected to multidimensional earthquake excitations. an improved multidimensional modal pushover analysis (IMMPA method is presented in the paper in order to estimate the response demands of structures subjected to bidirectional earthquake excitations, in which the unidirectional earthquake excitation applied on equivalent SDOF system is replaced by the direct superposition of two components earthquake excitations, and independent analysis in each direction is not required and the application of simplified superposition formulas is avoided. The strength reduction factor spectra based on superposition of earthquake excitations are discussed and compared with the traditional strength reduction factor spectra. The step-by-step procedure is proposed to estimate seismic demands of structures. Two examples are implemented to verify the accuracy of the method, and the results of the examples show that (1 the IMMPA method can be used to estimate the responses of structure subjected to bidirectional earthquake excitations. (2 Along with increase of peak of earthquake acceleration, structural response deviation estimated with the IMMPA method may also increase. (3 Along with increase of the number of total floors of structures, structural response deviation estimated with the IMMPA method may also increase.

  13. Bidirectional Text Messaging to Improve Adherence to Recommended Lipid Testing.

    Science.gov (United States)

    Baldwin, Laura-Mae; Morrison, Caitlin; Griffin, Jonathan; Anderson, Nick; Edwards, Kelly; Green, Jeff; Waldren, Cleary; Reiter, William

    2017-01-01

    Synergies between technology and health care in the United States are accelerating, increasing opportunities to leverage these technologies to improve patient care. This study was a collaboration between an academic study team, a rural primary care clinic, and a local nonprofit informatics company developing tools to improve patient care through population management. Our team created a text messaging management tool, then developed methods for and tested the feasibility of bidirectional text messaging to remind eligible patients about the need for lipid testing. We measured patient response to the text messages, then interviewed 8 patients to explore their text messaging experience. Of the 129 patients the clinic was able to contact by phone, 29.4% had no cell phone or text-messaging capabilities. An additional 20% refused to participate. Two thirds of the 28 patients who participated in the text messaging intervention (67.9%) responded to at least 1 of the up to 3 messages. Seven of 8 interviewed patients had a positive text-messaging experience. Bidirectional text messaging is a feasible and largely acceptable form of communication for test reminders that has the potential to reach large numbers of patients in clinical care. © Copyright 2017 by the American Board of Family Medicine.

  14. Bidirectional Relations between Temperament and Parenting Styles in Chinese Children.

    Science.gov (United States)

    Lee, Erica H; Zhou, Qing; Eisenberg, Nancy; Wang, Yun

    2013-01-01

    The present study examined bidirectional relations between child temperament and parenting styles in a sample ( n = 425) of Chinese children during elementary school period (age range = 6 to 9 years at Wave 1). Using two waves (3.8 years apart) of longitudinal data, we tested two hypotheses: (1) whether child temperament (effortful control and anger/frustration) at Wave 1 predicts parenting styles (authoritative and authoritarian parenting) at Wave 2, controlling for Wave 1 parenting; and (2) whether parenting styles at Wave 1 predict Wave 2 temperament, controlling for Wave 1 temperament. We found support for bidirectional relations between temperament and authoritarian parenting, such that higher effortful control and lower anger/frustration were associated with higher authoritarian parenting across time and in both directions. There were no significant cross-time associations between children's temperament and authoritative parenting. These findings extend the previous tests of transactional relations between child temperament and parenting in Chinese children and are consistent with the cultural values toward effortful control and control of anger/frustration in Chinese society.

  15. Evolutionary Pseudo-Relaxation Learning Algorithm for Bidirectional Associative Memory

    Institute of Scientific and Technical Information of China (English)

    Sheng-Zhi Du; Zeng-Qiang Chen; Zhu-Zhi Yuan

    2005-01-01

    This paper analyzes the sensitivity to noise in BAM (Bidirectional Associative Memory), and then proves the noise immunity of BAM relates not only to the minimum absolute value of net inputs (MAV) but also to the variance of weights associated with synapse connections. In fact, it is a positive monotonically increasing function of the quotient of MAV divided by the variance of weights. Besides, the performance of pseudo-relaxation method depends on learning parameters (λ and ζ), but the relation of them is not linear. So it is hard to find a best combination of λ and ζ which leads to the best BAM performance. And it is obvious that pseudo-relaxation is a kind of local optimization method, so it cannot guarantee to get the global optimal solution. In this paper, a novel learning algorithm EPRBAM (evolutionary psendo-relaxation learning algorithm for bidirectional association memory) employing genetic algorithm and pseudo-relaxation method is proposed to get feasible solution of BAM weight matrix. This algorithm uses the quotient as the fitness of each individual and employs pseudo-relaxation method to adjust individual solution when it does not satisfy constraining condition any more after genetic operation. Experimental results show this algorithm improves noise immunity of BAM greatly. At the same time, EPRBAM does not depend on learning parameters and can get global optimal solution.

  16. Hormone response to bidirectional selection on social behavior.

    Science.gov (United States)

    Amdam, Gro V; Page, Robert E; Fondrk, M Kim; Brent, Colin S

    2010-01-01

    Behavior is a quantitative trait determined by multiple genes. Some of these genes may have effects from early development and onward by influencing hormonal systems that are active during different life-stages leading to complex associations, or suites, of traits. Honey bees (Apis mellifera) have been used extensively in experiments on the genetic and hormonal control of complex social behavior, but the relationships between their early developmental processes and adult behavioral variation are not well understood. Bidirectional selective breeding on social food-storage behavior produced two honey bee strains, each with several sublines, that differ in an associated suite of anatomical, physiological, and behavioral traits found in unselected wild type bees. Using these genotypes, we document strain-specific changes during larval, pupal, and early adult life-stages for the central insect hormones juvenile hormone (JH) and ecdysteroids. Strain differences correlate with variation in female reproductive anatomy (ovary size), which can be influenced by JH during development, and with secretion rates of ecdysteroid from the ovaries of adults. Ovary size was previously assigned to the suite of traits of honey bee food-storage behavior. Our findings support that bidirectional selection on honey bee social behavior acted on pleiotropic gene networks. These networks may bias a bee's adult phenotype by endocrine effects on early developmental processes that regulate variation in reproductive traits. © 2010 Wiley Periodicals, Inc.

  17. Bidirectional Microglia-Neuron Communication in the Healthy Brain

    Directory of Open Access Journals (Sweden)

    Ukpong B. Eyo

    2013-01-01

    Full Text Available Unlike other resident neural cells that are of neuroectodermal origin, microglia are resident neural cells of mesodermal origin. Traditionally recognized for their immune functions during disease, new roles are being attributed to these cells in the development and maintenance of the central nervous system (CNS including specific communication with neurons. In this review, we highlight some of the recent findings on the bidirectional interaction between neurons and microglia. We discuss these interactions along two lines. First, we review data that suggest that microglial activity is modulated by neuronal signals, focusing on evidence that (i neurons are capable of regulating microglial activation state and influence basal microglial activities; (ii classic neurotransmitters affect microglial behavior; (iii chemotactic signals attract microglia during acute neuronal injury. Next, we discuss some of the recent data on how microglia signal to neurons. Signaling mechanisms include (i direct physical contact of microglial processes with neuronal elements; (ii microglial regulation of neuronal synapse and circuit by fractalkine, complement, and DAP12 signaling. In addition, we discuss the use of microglial depletion strategies in studying the role of microglia in neuronal development and synaptic physiology. Deciphering the mechanisms of bidirectional microglial-neuronal communication provides novel insights in understanding microglial function in both the healthy and diseased brain.

  18. Bidirectional Dynamic Diversity Evolutionary Algorithm for Constrained Optimization

    Directory of Open Access Journals (Sweden)

    Weishang Gao

    2013-01-01

    Full Text Available Evolutionary algorithms (EAs were shown to be effective for complex constrained optimization problems. However, inflexible exploration-exploitation and improper penalty in EAs with penalty function would lead to losing the global optimum nearby or on the constrained boundary. To determine an appropriate penalty coefficient is also difficult in most studies. In this paper, we propose a bidirectional dynamic diversity evolutionary algorithm (Bi-DDEA with multiagents guiding exploration-exploitation through local extrema to the global optimum in suitable steps. In Bi-DDEA potential advantage is detected by three kinds of agents. The scale and the density of agents will change dynamically according to the emerging of potential optimal area, which play an important role of flexible exploration-exploitation. Meanwhile, a novel double optimum estimation strategy with objective fitness and penalty fitness is suggested to compute, respectively, the dominance trend of agents in feasible region and forbidden region. This bidirectional evolving with multiagents can not only effectively avoid the problem of determining penalty coefficient but also quickly converge to the global optimum nearby or on the constrained boundary. By examining the rapidity and veracity of Bi-DDEA across benchmark functions, the proposed method is shown to be effective.

  19. Prenatal surgery for myelomeningocele and the need for cerebrospinal fluid shunt placement

    Science.gov (United States)

    Tulipan, Noel; Wellons, John C.; Thom, Elizabeth A.; Gupta, Nalin; Sutton, Leslie N.; Burrows, Pamela K.; Farmer, Diana; Walsh, William; Johnson, Mark P.; Rand, Larry; Tolivaisa, Susan; D’Alton, Mary E.; Adzick, N. Scott

    2016-01-01

    Object The Management of Myelomeningocele Study (MOMS) was a multicenter randomized trial comparing the safety and efficacy of prenatal and postnatal closure of myelomeningocele. The trial was stopped early because of the demonstrated efficacy of prenatal surgery, and outcomes on 158 of 183 pregnancies were reported. Here, the authors update the 1-year outcomes for the complete trial, analyze the primary and related outcomes, and evaluate whether specific prerandomization risk factors are associated with prenatal surgery benefit. Methods The primary outcome was a composite of fetal loss or any of the following: infant death, CSF shunt placement, or meeting the prespecified criteria for shunt placement. Primary outcome, actual shunt placement, and shunt revision rates for prenatal versus postnatal repair were compared. The shunt criteria were reassessed to determine which were most concordant with practice, and a new composite outcome was created from the primary outcome by replacing the original criteria for CSF shunt placement with the revised criteria. The authors used logistic regression to estimate whether there were interactions between the type of surgery and known prenatal risk factors (lesion level, gestational age, degree of hindbrain herniation, and ventricle size) for shunt placement, and to determine which factors were associated with shunting among those infants who underwent prenatal surgery. Results Ninety-one women were randomized to prenatal surgery and 92 to postnatal repair. The primary outcome occurred in 73% of infants in the prenatal surgery group and in 98% in the postnatal group (p < 0.0001). Actual rates of shunt placement were only 44% and 84% in the 2 groups, respectively (p < 0.0001). The authors revised the most commonly met criterion to require overt clinical signs of increased intracranial pressure, defined as split sutures, bulging fontanelle, or sunsetting eyes, in addition to increasing head circumference or hydrocephalus. Using

  20. [Thomas' shunt for hemodialysis: dysfunction and its percutaneous treatment].

    Science.gov (United States)

    Gallego, J J; Santos, E; Méndez, J V; Coronel, F; Torrente, J; Holguín, A; Moreno, R

    2003-01-01

    To assess the usefulness of percutaneous treatment of abnormalities of the venous tree in extending the survival of external Thomas shunts (TS). Twelve cases of TS were included in a hemodialysis access fistula dysfunction monitoring program and were followed for up to 48 months. The abnormalities found were treated by percutaneous transluminal angioplasty (PTA) or thrombolysis and PTA. Survival curves and the Kaplan-Meier method were used to calculate the likelihood of primary patency (P1), secondary patency (P2), and overall patency (OP). A total of 61 interventions were performed during the period of follow-up. On 12 occasions the fistula was thrombosed; in the rest, increased venous pressure to 150 mmHg or higher was detected during dialysis. Fistulography was performed after washing the thrombosed fistulas with urokinase, and revealed one or more of the following angiographic signs: 1) a short reduction of more than 50% in lumen caliber in the femoral vein adjacent to the anastomosis, present in 52% of the cases (fig. 1); 2) imaging a "jet" of contrast material at the site of entry of the shunt into the femoral vein (fig. 2), present in 22% of the cases; and 3) a filling defect or "flap" at the same site, owing to hyperplastic tissue or piece of thrombus adhering to the intima, present in 34% of the cases (figs. 3-5). This last-mentioned finding ordinarily gave rise to a "valve" effect, whereby injection into the venous branch was feasible but aspiration from the venous branch was difficult or impossible. PTA was carried out and attained anatomical and functional success in 100% of cases. PI was 58%, 33%, 8%, and 0% at 6, 12, 24, and 36 months, respectively; P2 was 100%, 75%, 58%, and 25%; respectively, at those same times. The comparison of the PI and P2 curves was statistically significant; p < 0.001 (table 1). OP was 83%, 66%, 50% and 41% at 12, 24, 36 and 48 months. The comparison of the PI surgical and OP curves was statistically significant; p < 0

  1. A programme for bidirectional phonology and phonetics and their acquisition and evolution

    NARCIS (Netherlands)

    Boersma, P.; Benz, A.; Mattausch, J.

    2011-01-01

    This paper summarizes an existing bidirectional six-level model of phonology and phonetics (and a bit of morphology). Bidirectionality in this case refers to the modelling of both the speaking process (production) and the listening process (comprehension). The elements of the grammar (the

  2. Global evaluation of ammonia bidirectional exchange and livestock diurnal variation schemes

    Science.gov (United States)

    Bidirectional air–surface exchange of ammonia (NH3) has been neglected in many air quality models. In this study, we implement the bidirectional exchange of NH3 in the GEOS-Chem global chemical transport model. We also introduce an updated diurnal variability scheme for NH3...

  3. Bidirectional communication in an HF hybrid organic/solution-processed metal-oxide RFID tag

    NARCIS (Netherlands)

    Myny, K.; Rockelé, M.; Chasin, A.; Pham, D.V.; Steiger, J.; Botnaras, S.; Weber, D.; Herold, B.; Ficker, J.; Van Putten, B.D.; Gelinck, G.H.; Genoe, J.; Dehaene, W.; Heremans, P.

    2014-01-01

    A bidirectional communication protocol allows radio-frequency identification (RFID) tags to have readout of multiple tags in the RF field without collision of data. In this paper, we realized bidirectional communication between a reader system and thin-film RFID tag by introducing a novel protocol

  4. Numerical Modelling of a Bidirectional Long Ring Raman Fiber Laser Dynamics

    Science.gov (United States)

    Sukhanov, S. V.; Melnikov, L. A.; Mazhirina, Yu A.

    2017-11-01

    The numerical model for the simulation of the dynamics of a bidirectional long ring Raman fiber laser is proposed. The model is based on the transport equations and Courant-Isaacson-Rees method. Different regimes of a bidirectional long ring Raman fiber laser and long time-domain realizations are investigated.

  5. Radionuclide angiocardiography. Improved diagnosis and quantitation of left-to-right shunts using area ratio techniques in children

    International Nuclear Information System (INIS)

    Alderson, P.O.; Jost, R.G.; Strauss, A.W.; Boonvisut, S.; Markham, J.

    1975-01-01

    A comparison of several reported methods for detection and quantitation of left-to-right shunts by radionuclides was performed in 50 children. Count ratio (C2/C1) techniques were compared with the exponential extrapolation and gamma function area ratio techniques. C2/C1 ratios accurately detected shunts and could reliably separate shunts from normals, but there was a high rate of false positives in children with valvular heart disease. The area ratio methods provided more accurate shunt quantitation and a better separation of patients with valvular heart disease than did the C2/C1 ratio. The gamma function method showed a higher correlation with oximetry than the exponential method, but the difference was not statistically significant. For accurate shunt quantitation and a reliable separation of patients with valvular heart disease from those with shunts, area ratio calculations are preferable to the C2/C1 ratio

  6. Effects of isradipine and other calcium antagonists on arteriovenous-shunt flow in anesthetized rabbits and cats

    International Nuclear Information System (INIS)

    Hof, R.P.

    1989-01-01

    The effects of vasodilators on arteriovenous (AV)-shunt flow was investigated in anesthetized cats and rabbits, using the tracer microsphere method. In cats, the calcium antagonist isradipine reduced AV-shunt flow; verapamil showed a similar tendency and nicardipine was without effect. Dihydralazine strongly increased, but nitroglycerin and dipyridamole decreased AV-shunt flow. In rabbits, the effects of isradipine and verapamil were similar to those seen in cats. Sodium nitroprusside had no effect, whereas prazosin, minoxidil, and the potassium-channel activator cromakalim increased AV-shunt flow. The contrasting effects of drugs sharing the same mechanism of action suggest that target-tissue selectivity is more important than the mechanism of action. An increase of AV-shunt flow is unlikely to be beneficial but could be associated with a number of undesirable side effects. It might negatively affect migraine sufferers and, if AV-shunt dilatation shows no tolerance development, it represents an unnecessary hemodynamic burden for the heart

  7. The use of abdominal binders to treat over-shunting headaches.

    Science.gov (United States)

    Sklar, Frederick H; Nagy, Laszlo; Robertson, Brian D

    2012-06-01

    Headaches are common in children with shunts. Headaches associated with over-shunting are typically intermittent and tend to occur later in the day. Lying down frequently makes the headaches better. This paper examines the efficacy of using abdominal binders to treat over-shunting headaches. Over an 18-year period, the senior author monitored 1027 children with shunts. Office charts of 483 active patients were retrospectively reviewed to identify those children with headaches and, in particular, those children who were thought to have headaches as a result of over-shunting. Abdominal binders were frequently used to treat children with presumed over-shunting headaches, and these data were analyzed. Of the 483 patients undergoing chart review, 258 (53.4%) had headache. A clinical diagnosis of over-shunting was made in 103 patients (21.3% overall; 39.9% of patients with headache). In 14 patients, the headaches were very mild (1-2 on a 5-point scale) and infrequent (1 or 2 per month), and treatment with an abdominal binder was not thought indicated. Eighty-nine patients were treated with a binder, but 19 were excluded from this retrospective study for noncompliance, interruption of the binder trial, or lack of follow-up. The remaining 70 pediatric patients, who were diagnosed with over-shunting headaches and were treated with abdominal binders, were the subjects of a more detailed retrospective study. Significant headache improvement was observed in 85.8% of patients. On average, the patients wore the binders for approximately 1 month, and headache relief usually persisted even after the binders were discontinued. However, the headaches eventually did recur in many of the patients more than a year later. In these patients, reuse of the abdominal binder was successful in relieving headaches in 78.9%. The abdominal binder is an effective, noninvasive therapy to control over-shunting headaches in most children. This treatment should be tried before any surgery is

  8. Oculo-peritoneal shunt: draining aqueous humor to the peritoneum

    Directory of Open Access Journals (Sweden)

    Ana Maldonado-Junyent

    2015-04-01

    Full Text Available In 2010, there were estimated to be approximately 60.5 million people with glaucoma. This number is expected to increase to 79.6 million by 2020. In 2010, there were 8.4 million people with bilateral blindness caused by glaucoma, and this number is expected in increase to 11.2 million by 2020. Filtering implants are special devices that have been developed to reduce intraocular pressure in patients with refractory glaucoma. The success rate of these implants is relatively low, and they continue to fail over time. To avoid failure caused by the formation of scar tissue around the implants, attempts have been made to drain the aqueous humor to various sites, including the venous system, lacrimal sac, sinuses, and conjunctival fornix. Recently, a system to shunt aqueous humor from the anterior chamber to the peritoneum has been developed. The surgical technique involved in this system is a modification of the technique currently used by neurosurgeons for the treatment of hydrocephalus. We present the first case operated using this technique.

  9. Integrated fuel cell stack shunt current prevention arrangement

    Energy Technology Data Exchange (ETDEWEB)

    Roche, Robert P. (Cheshire, CT); Nowak, Michael P. (Bolton, CT)

    1992-01-01

    A fuel cell stack includes a plurality of fuel cells juxtaposed with one another in the stack and each including a pair of plate-shaped anode and cathode electrodes that face one another, and a quantity of liquid electrolyte present at least between the electrodes. A separator plate is interposed between each two successive electrodes of adjacent ones of the fuel cells and is unified therewith into an integral separator plate. Each integral separator plate is provided with a circumferentially complete barrier that prevents flow of shunt currents onto and on an outer peripheral surface of the separator plate. This barrier consists of electrolyte-nonwettable barrier members that are accommodated, prior to the formation of the integral separator plate, in corresponding edge recesses situated at the interfaces between the electrodes and the separator plate proper. Each barrier member extends over the entire length of the associated marginal portion and is flush with the outer periphery of the integral separator plate. This barrier also prevents cell-to-cell migration of any electrolyte that may be present at the outer periphery of the integral separator plate while the latter is incorporated in the fuel cell stack.

  10. Hyperglucagonemia and hyperkinetic circulation after portocaval shunt in the rat

    International Nuclear Information System (INIS)

    Kravetz, D.; Arderiu, M.; Bosch, J.; Fuster, J.; Visa, J.; Casamitjana, R.; Rodes, J.

    1987-01-01

    The study was aimed at investigating whether increased portal venous inflow (PVI) after portocaval shunt (PCS) in the rat is the result of selective splanchnic vasodilatation or whether it is part of a generalized circulatory disturbance. Rats with PCS and sham-operated controls were studied 2 wk after surgery by measuring cardiac output (CO), PVI, and hepatic artery flow (HAF) with radioactive microspheres ( 51 Cr and 14 C). Plasma glucagon (GL) was measured by radioimmunoassay. PCS rats had increased CO and reduced arterial pressure and total peripheral resistance. PVI was markedly increased, but this appeared to be part of a generalized circulatory disturbance, since when PVI is expressed as percent of CO no difference is observed between PCS and sham-operated rats, indicating the absence of a preferential splanchnic vasodilatation. GL increased after PCS, and significant correlations were observed between GL and CO and between GL and PVI. HAF increased after PCS but did not compensate the loss of portal flow, evidence by a lower total hepatic flow in PCS rats. These results suggest that PCS induces a hyperkinetic circulatory state in which increased PVI represents its splanchnic manifestation and that increased GL release may be in part responsible for these hemodynamic changes

  11. Radiation doses to children with shunt-treated hydrocephalus

    Energy Technology Data Exchange (ETDEWEB)

    Holmedal, Lise J. [Helse Fonna, Department of Radiology, Stord Hospital, Stord (Norway); Friberg, Eva G.; Boerretzen, Ingelin; Olerud, Hilde [The Norwegian Radiation Protection Authority, Oesteraas (Norway); Laegreid, Liv [Haukeland University Hospital, Department of Paediatrics, Bergen (Norway); Rosendahl, Karen [University of Bergen, Department of Surgical Sciences, Radiology Section, Bergen (Norway); Great Ormond Street Hospital for Children, Department of Diagnostic Radiology, London (United Kingdom)

    2007-12-15

    Children with shunt-treated hydrocephalus are still followed routinely with frequent head CT scans. To estimate the effective dose, brain and lens doses from these examinations during childhood, and to assess dose variation per examination. All children born between 1983 and 1995 and treated for hydrocephalus between 1983 and 2002 were included. We retrospectively registered the number of examinations and the applied scan parameters. The effective dose was calculated using mean conversion factors from the CT dose index measured free in air, while doses to the lens and brain were estimated using tabulated CT dose index values measured in a head phantom. A total of 687 CT examinations were performed in 67 children. The mean effective dose, lens dose and brain dose to children over 6 months of age were 1.2 mSv, 52 mGy and 33 mGy, respectively, and the corresponding doses to younger children were 3.2 mSv, 60 mGy and 48 mGy. The effective dose per CT examination varied by a factor of 64. None of the children was exposed to doses known to cause deterministic effects. However, since the threshold for radiation-induced damage is not known with certainty, alternative modalities such as US and MRI should be used whenever possible. (orig.)

  12. Transcaval transjugular intrahepatic portosystemic shunt: preliminary clinical results

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kwang Hun; Lee, Do Yun; Won, Jong Yoon [Yonsei University College of Medicine, Seoul (Korea, Republic of); Park, Sang Joon [Hallym University College of Medicine, Seoul (Korea, Republic of); Kim, Jae Kyu; Yoon, Woong [Chonnam National University Hospital, Gwangju (Korea, Republic of)

    2003-03-01

    To determine the feasibility of transcaval transjugular intrahepatic portosystemic shunt (TIPS) creation in patients with unusual anatomy between the hepatic veins and portal bifurcation, and inaccessible or inadequate hepatic veins. Transcaval TIPS, performed in six patients, was indicated by active variceal bleeding (n=2), recurrent variceal bleeding (n=2), intractable ascites (n=1), and as a bridge to liver transplantation (n=1). The main reasons for transcaval rather than classic TIPS were the presence of an unusually acute angle between the hepatic veins and the level of the portal bifurcation (n=3), hepatic venous occlusion (n=2), and inadequate small hepatic veins (n=1). Technical and functional success was achieved in all patients. The entry site into liver parenchyma from the inferior vena cava was within 2 cm of the atriocaval junction. Procedure-related complications included the death of one patient due to hemoperitoneum despite the absence of contrast media spillage at tractography, and another suffered reversible hepatic encephalopathy. In patients with unusual anatomy between the hepatic veins and portal bifurcation, and inaccessible or inadequate hepatic veins, transcaval TIPS creation is feasible.

  13. Renal arteriovenous shunts, fistulae and malformations - angiographic case reports

    International Nuclear Information System (INIS)

    Esser, P.W.; Duex, A.

    1989-01-01

    Individual case reports serve to demonstrate the pathogenetically different renal arteriovenous shunt formations, such as congenital arteriovenous angioma, spontaneous arteriovenous aneurysm, iatrogenic arterio-venous fistula and neoplasia-conditioned arteriovenous fistula. These are discussed in detail, including treatment possibilities. The ranking of digital subtraction angiography is emphasised. Our case reports show that in preoperative diagnosis of pathological structures in the kidney, renovasography is an invaluable tool, especially with i.a. DSA technique, and is superior to all other methods such as sonography, CT, MR and colour-coded Doppler sonography. Due to improved techniques of angiography (markedly lower amounts of contrast medium when using catheters of narrow lumen) indication for i.a. DSA in haematuria of unknown origin should be liberal. Above all, the method should be performed at an early stage. If there is a NAD renal finding in the i.a. DSA renovasogram in renally conditioned haematuria even when using a 1024 x 1024 image matrix, it is advisable to perform selective renal arteriography to either exclude or confirm the existence of an intrarenal angioma, additionally in conventional sheet film technique because of the superior power of resolution. (orig.) [de

  14. Methionine metabolism after portacaval shunt in the rat

    International Nuclear Information System (INIS)

    Benjamin, L.E.; Steele, R.D.

    1985-01-01

    The effect of portacaval shunt (PCS) on methionine metabolism in the rat was investigated. Male Sprague-Dawley rats were subjected to PCS and maintained on an 18% casein diet. Growth curves of operated rats were similar to controls. PCS rats excreted more urinary 35 SO 4 and less [ 35 S]taurine than controls after intraperitoneal injection of 0.3 mmol/100 g [ 35 S]methionine or [ 35 S]cysteine. Total urinary taurine excretion was similar in PCS and control rats after a methionine or cysteine load; however, under basal conditions PCS rats had higher urinary taurine levels than controls, indicating that PCS may cause the taurine pool to be expanded. Hepatic methionine, S-adenosylmethionine, and cysteine pools were significantly decreased in PCS rats, while S-adenosylhomocysteine levels were unchanged. Relative rates of transsulfuration in PCS and control rats were studied by following the decrease in the 3 H-to- 35 S ratio in liver protein after injection of [methyl-3H]methionine and [ 35 S]methionine, and no difference in flux of 35 S from [ 35 S]methionine to [ 35 S]cysteine was found. Similarly, total hepatic activities of methionine adenosyltransferase, cystathionine synthase, and cystathionine gamma-lyase were unchanged in PCS rats. These results indicate that altered methionine metabolism in PCS rats is not explained by changes in conversion of methionine to cysteine via the transsulfuration pathway

  15. Transcaval transjugular intrahepatic portosystemic shunt: preliminary clinical results

    International Nuclear Information System (INIS)

    Lee, Kwang Hun; Lee, Do Yun; Won, Jong Yoon; Park, Sang Joon; Kim, Jae Kyu; Yoon, Woong

    2003-01-01

    To determine the feasibility of transcaval transjugular intrahepatic portosystemic shunt (TIPS) creation in patients with unusual anatomy between the hepatic veins and portal bifurcation, and inaccessible or inadequate hepatic veins. Transcaval TIPS, performed in six patients, was indicated by active variceal bleeding (n=2), recurrent variceal bleeding (n=2), intractable ascites (n=1), and as a bridge to liver transplantation (n=1). The main reasons for transcaval rather than classic TIPS were the presence of an unusually acute angle between the hepatic veins and the level of the portal bifurcation (n=3), hepatic venous occlusion (n=2), and inadequate small hepatic veins (n=1). Technical and functional success was achieved in all patients. The entry site into liver parenchyma from the inferior vena cava was within 2 cm of the atriocaval junction. Procedure-related complications included the death of one patient due to hemoperitoneum despite the absence of contrast media spillage at tractography, and another suffered reversible hepatic encephalopathy. In patients with unusual anatomy between the hepatic veins and portal bifurcation, and inaccessible or inadequate hepatic veins, transcaval TIPS creation is feasible

  16. Developmental trajectories of irritability and bidirectional associations with maternal depression.

    Science.gov (United States)

    Wiggins, Jillian Lee; Mitchell, Colter; Stringaris, Argyris; Leibenluft, Ellen

    2014-11-01

    Irritability is a dimensional trait in typical development and a common presenting symptom in many psychiatric disorders, including depression. However, little is known about the developmental trajectory of irritability or how child irritability interacts with maternal depression. The present study identifies classes of irritability trajectories from toddlerhood to middle childhood; characterizes maternal depression and other family, social environment, and child variables within each irritability trajectory class; and, as a more exploratory analysis, examines bidirectional associations between maternal depression and child irritability. A total of 4,898 families from the Fragile Families and Child Wellbeing Study reported on irritability symptoms at ages 3, 5, and 9 years, assessed with items from the Child Behavior Checklist. Parental major depressive episode was assessed using the Composite International Diagnostic Interview-Short Form at child ages 1, 3, 5, and 9 years. A latent class growth analysis identified 5 irritability classes: low decreasing; moderate decreasing; high steady; initially very high, then decreasing; and high increasing. Children with more severe irritability trajectories are more likely to have mothers with recurrent depression, and, with the exception of the most severe (high increasing irritability) class, were more likely to have mothers who were exposed to violence. Moreover, paternal depression and alcohol abuse, as well as maternal drug and alcohol abuse, were also risk factors for membership in the more severe irritability classes. A latent auto-regressive cross-lag model showed that child irritability at ages 3 and 5 years is associated with increased mother depression at ages 5 and 9, respectively. Conversely, mother depression at child ages 1 and 3 years is associated with increased child irritability at 3 and 5. Irritability development across toddlerhood and middle childhood has 5 main trajectory types, which differ on maternal

  17. Analysis of snow bidirectional reflectance from ARCTAS Spring-2008 Campaign

    Directory of Open Access Journals (Sweden)

    A. Lyapustin

    2010-05-01

    Full Text Available The spring 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS experiment was one of major intensive field campaigns of the International Polar Year aimed at detailed characterization of atmospheric physical and chemical processes in the Arctic region. A part of this campaign was a unique snow bidirectional reflectance experiment on the NASA P-3B aircraft conducted on 7 and 15 April by the Cloud Absorption Radiometer (CAR jointly with airborne Ames Airborne Tracking Sunphotometer (AATS and ground-based Aerosol Robotic Network (AERONET sunphotometers. The CAR data were atmospherically corrected to derive snow bidirectional reflectance at high 1° angular resolution in view zenith and azimuthal angles along with surface albedo. The derived albedo was generally in good agreement with ground albedo measurements collected on 15 April. The CAR snow bidirectional reflectance factor (BRF was used to study the accuracy of analytical Ross-Thick Li-Sparse (RTLS, Modified Rahman-Pinty-Verstraete (MRPV and Asymptotic Analytical Radiative Transfer (AART BRF models. Except for the glint region (azimuthal angles φ<40°, the best fit MRPV and RTLS models fit snow BRF to within ±0.05. The plane-parallel radiative transfer (PPRT solution was also analyzed with the models of spheres, spheroids, randomly oriented fractal crystals, and with a synthetic phase function. The latter merged the model of spheroids for the forward scattering angles with the fractal model in the backscattering direction. The PPRT solution with synthetic phase function provided the best fit to measured BRF in the full range of angles. Regardless of the snow grain shape, the PPRT model significantly over-/underestimated snow BRF in the glint/backscattering regions, respectively, which agrees with other studies. To improve agreement with experiment, we introduced a model of macroscopic snow surface roughness by averaging the PPRT solution over the

  18. Analysis of Snow Bidirectional Reflectance from ARCTAS Spring-2008 Campaign

    Science.gov (United States)

    Lyapustin, A.; Gatebe, C. K.; Redemann, J.; Kahn, R.; Brandt, R.; Russell, P.; King, M. D.; Pedersen, C. A.; Gerland, S.; Poudyal, R.; hide

    2010-01-01

    The spring 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) experiment was one of major intensive field campaigns of the International Polar Year aimed at detailed characterization of atmospheric physical and chemical processes in the Arctic region. A part of this campaign was a unique snow bidirectional reflectance experiment on the NASA P-3B aircraft conducted on 7 and 15 April by the Cloud Absorption Radiometer (CAR) jointly with airborne Ames Airborne Tracking Sunphotometer (AATS) and ground-based Aerosol Robotic Network (AERONET) sunphotometers. The CAR data were atmospherically corrected to derive snow bidirectional reflectance at high 1 degree angular resolution in view zenith and azimuthal angles along with surface albedo. The derived albedo was generally in good agreement with ground albedo measurements collected on 15 April. The CAR snow bidirectional reflectance factor (BRF) was used to study the accuracy of analytical Ross-Thick Li-Sparse (RTLS), Modified Rahman-Pinty-Verstraete (MRPV) and Asymptotic Analytical Radiative Transfer (AART) BRF models. Except for the glint region (azimuthal angles phi less than 40 degrees), the best fit MRPV and RTLS models fit snow BRF to within 0.05. The plane-parallel radiative transfer (PPRT) solution was also analyzed with the models of spheres, spheroids, randomly oriented fractal crystals, and with a synthetic phase function. The latter merged the model of spheroids for the forward scattering angles with the fractal model in the backscattering direction. The PPRT solution with synthetic phase function provided the best fit to measured BRF in the full range of angles. Regardless of the snow grain shape, the PPRT model significantly over-/underestimated snow BRF in the glint/backscattering regions, respectively, which agrees with other studies. To improve agreement with experiment, we introduced a model of macroscopic snow surface roughness by averaging the PPRT solution

  19. Spontaneous resolution of splenic infarcts after distal splenorenal shunt in children with extra hepatic portal venous obstruction: Our experience

    Directory of Open Access Journals (Sweden)

    Arbinder Kumar

    2014-01-01

    Full Text Available Background: In cases of portal hypertension with splenic infarcts, splenectomy with proximal splenorenal shunt has been recommended. We are sharing our experience with distal splenorenal shunt in these cases contrary to the popular belief. Materials and Methods: Splenic infarcts were graded as mild, moderate and severe according to the pre-operative CT portogram. Mild, moderate and severe infarcts were defined as an infarct involving 50% area of the spleen, respectively. Mild and moderate infarcts were managed by spleen-preserving distal splenorenal shunt while those with extensive infarcts were subjected to splenectomy and proximal splenorenal shunt. Those with spleen-preserving shunts were closely followed in the post-operative period according to a uniform protocol. Clinical examination was regularly done to assess the size of the spleen and note the presence of pain, tenderness in the left intercostal space. An ultrasound Doppler was done after 7 days to assess shunt patency while CT portogram was repeated at 6 monthly intervals. Results: Fourteen cases with splenic infarcts formed the study group. Eight cases had mild infarcts, 3 had moderate infarcts and 3 had severe infarcts. Four underwent proximal splenorenal shunt, and 10 underwent warren′s shunt (8 with mild and 2 with moderate infarcts. In 9/10 (90%, spleen could eventually be retained. Spleen completely regressed in them and so did the infarct. Conclusions:Spleen-preserving distal splenorenal shunt can be considered as a viable option in the management of cases with mild and carefully selected moderate splenic infarcts.

  20. [The use of labelled albumin microspheres in the study of arteriovenous shunting in varicosities of the lower limbs (author's transl)].

    Science.gov (United States)

    Serise, J M; Le Héron, D; Le Héron, G; Bonnet, A; Busquet, J; Basse-Cathalinat, B; Tingaud, R

    1982-01-01

    The greater proportion of oxygen in the blood circulating in veins of the lower limbs bought to attention the possibility of pre-capillary arteriovenous shunting. The intra-arteriel injection of Technetium labelled serum albumin microspheres enables one to quantify arteriovenous shunts greater than 25 microns. The authors made a comparative study of arterio-venous shunting by blood gases analysis and isotopic techniques in twenty patients. The results seem to deny the existence of arteriovenous shunts in the genesis of essential varicose veins in the lower limb.

  1. Cerebral Blood Flow Changes after Shunt in Hydrocephalus after Aneurysmal Subarachnoid Hemorrhage: Analysis by statistical Parametric Mapping

    International Nuclear Information System (INIS)

    Hyun, I. Y.; Choi, W. S.; Pak, H. S.

    2003-01-01

    The purpose of this study was to evaluate the changes of regional cerebral blood flow (rCBF) after shunt operation in patients with hydrocephalus after aneurysmal subarachnoid hemorrhage ba statistical parametric mapping (SPM). Seven patients (4 male, mean age 54 years) with hydrocephalus after aneurysmal subarachnoid hemorrhage underwent a shunt operation. Tc-99m HMPAO SPECT was performed within I week before, and 2 weeks after the shunt operation. All of the SPECT images were spatially transformed to standard space, smoothed, and globally normalized. After spatial and count normalization, rCBF of pre- and post- shunting Tc- 99m HMPAO SPECT was estimated at every voxel using t statistics. The voxels with a P value of less than 0.001 were considered to be significantly different. The shunt operation was effective in all patients. Pre-shunting Tc-99m HMPAO SPECT showed hypoperfusion, predominantly in the periventricular area. After shunt operation, periventricular low perfusion was disappeared. The results of this study show that periventricular CBF is impaired in hydrocephalus after aneurysmal subarachnoid hemorrhage. Significant increase of periventricular CBF after shunt operation suggests the evaluation of periventricular CBF by SPM might be of value for the prediction of shunt effectiveness in hydrocephalus

  2. The clinical application and nursing experience of adjustable shunt valve in treatment for patients with normal pressure hydrocephalus

    Directory of Open Access Journals (Sweden)

    YANG Li-rong

    2012-02-01

    Full Text Available Objective To introduce the application of adjustable shunt valve in treatment for patients with normal pressure hydrocephalus. Methods Twenty-four patients with normal pressure hydrocephalus implanted adjustable shunt valve underwent ventriculo-peritoneal shunt surgery and nursing care. Results After operation, cerebrospinal pressure was regulated for 0-6 (1.88 ± 1.52 times. Clinical symptoms were improved, especially in gait disturbance. Conclusion Treatment of normal pressure hydrocephalus with adjustable shunt valve can alleviate symptoms of hydrocephalus. It is especially suitable for patients with short course and secondary normal hydrocephalus patients.

  3. Cerebral Blood Flow Changes after Shunt in Hydrocephalus after Aneurysmal Subarachnoid Hemorrhage: Analysis by statistical Parametric Mapping

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, I. Y.; Choi, W. S.; Pak, H. S. [College of Medicine, Univ. of Inhwa, Incheon (Korea, Republic of)

    2003-07-01

    The purpose of this study was to evaluate the changes of regional cerebral blood flow (rCBF) after shunt operation in patients with hydrocephalus after aneurysmal subarachnoid hemorrhage ba statistical parametric mapping (SPM). Seven patients (4 male, mean age 54 years) with hydrocephalus after aneurysmal subarachnoid hemorrhage underwent a shunt operation. Tc-99m HMPAO SPECT was performed within I week before, and 2 weeks after the shunt operation. All of the SPECT images were spatially transformed to standard space, smoothed, and globally normalized. After spatial and count normalization, rCBF of pre- and post- shunting Tc- 99m HMPAO SPECT was estimated at every voxel using t statistics. The voxels with a P value of less than 0.001 were considered to be significantly different. The shunt operation was effective in all patients. Pre-shunting Tc-99m HMPAO SPECT showed hypoperfusion, predominantly in the periventricular area. After shunt operation, periventricular low perfusion was disappeared. The results of this study show that periventricular CBF is impaired in hydrocephalus after aneurysmal subarachnoid hemorrhage. Significant increase of periventricular CBF after shunt operation suggests the evaluation of periventricular CBF by SPM might be of value for the prediction of shunt effectiveness in hydrocephalus.

  4. Reduction of shunt obstructions by using a peel-away sheath technique? A multicenter prospective randomized trial.

    Science.gov (United States)

    Kehler, Uwe; Langer, Niels; Gliemroth, Jan; Meier, Ullrich; Lemcke, Johannes; Sprung, Christian; Schlosser, Hans-Georg; Kiefer, Michael; Eymann, Regina; Heese, Oliver

    2012-05-01

    Shunt obstructions may partly be caused by brain debris, which intrude into the ventricular catheter during ventricle puncture. Avoiding contact between the catheter and brain tissue, by using a peel-away sheath, should reduce the number of shunt failures caused by obstruction. To test this hypothesis, we conducted a randomized, prospective multicenter study. 201 patients from 6 different neurosurgical centers in Germany receiving a ventriculo-peritoneal shunt were included in this study. Of these, 177 patients completed a 1-year follow-up period. Surgery was randomized in a 1 to 1 fashion, such that out of 177 procedures, 91 were performed using a peel-away sheath and 86 were performed without. The rate of surgical re-interventions and shunt obstructions within a 12-month period was recorded. Within 1 year post-surgery, 17 shunt obstructions (9.6%) leading to shunt revisions were recorded. However, no difference was found between surgeries performed using a peel-away sheath (9.9%) or not (9.3%). The overall shunt infection rate was 2.8% and the shunt revision rate for overdrainage was 3.9%. The theoretical advantages attributed to the use of a peel-away sheath to introduce a ventricular catheter could not be confirmed in this randomized study, suggesting that the proposed role of brain debris in shunt obstructions may be overestimated. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Conversion of Low-Flow Priapism to High-Flow State Using T-Shunt with Tunneling.

    Science.gov (United States)

    Mistry, Neil A; Tadros, Nicholas N; Hedges, Jason C

    2017-01-01

    Introduction . The three types of priapism are stuttering, arterial (high-flow, nonischemic), and venoocclusive (low-flow, ischemic). These are usually distinct entities and rarely occur in the same patient. T-shunts and other distal shunts are frequently combined with tunneling, but a seldom recognized potential complication is conversion to a high-flow state. Case Presentation . We describe 2 cases of men who presented with low-flow priapism episodes that were treated using T-shunts with tunneling that resulted with both men having recurrent erections shortly after surgery that were found to be consistent with high-flow states. Case 1 was a 33-year-old male with sickle cell anemia and case 2 was a 24-year-old male with idiopathic thrombocytopenic purpura. In both cases the men were observed over several weeks and both men returned to normal erectile function. Conclusions . Historically, proximal shunts were performed only in cases when distal shunts failed and carry a higher risk of serious complications. T-shunts and other distal shunts combined with tunneling are being used more frequently in place of proximal shunts. These cases illustrate how postoperative erections after T-shunts with tunneling can signify a conversion from low-flow to high-flow states and could potentially be misdiagnosed as an operative failure.

  6. Angiographic and hemodynamic evaluation of the mesoatrial shunt in patients with Budd-Chiari syndrome and inferior vena caval obstruction

    International Nuclear Information System (INIS)

    Redmond, P.L.; Kadir, S.; Cameron, J.L.; Kaufman, S.L.; White, R.I. Jr.

    1986-01-01

    Obstruction of the inferior vena cava (IVC) is not uncommon in patients with the Budd-Chiari syndrome. The caval obstruction may be due to thrombus or compression by an enlarged caudate lobe. Conventional portosystemic shunts are not possible in the presence of an obstructed IVC; the mesoatrial shunt is indicated in these patients. Between 1973 and 1986, the authors studied 13 patients (ten female, three male) with Budd-Chiari syndrome and IVC obstruction in whom mesoatrial shunts were subsequently constructed. Polycythemia rubra vera was the most common predisposing condition. Preoperative evaluation included US, scintigraphy, CT, and angiography (hepatic arteriography, hepatic venography and pressure measurements, inferior vena cavography, arterial portography). Postoperatively shunts were assessed angiographically and hemodynamically, and several patients underwent CT. The shunts were catheterized via a brachial or femoral venous approach, which allowed pressures along the shunt from the superior mesenteric vein to the right atrium to be measured. The mesoatrial shunt is a relatively new procedure which is indicated in patients with the Budd-Chiari syndrome complicated by IVC obstruction. Shunt patency may be demonstrated arteriographically or with CT, but hemodynamic evaluation with measurement of pressure gradients is required to assess shunt function

  7. Post-TIPS Hepatic Encephalopathy Treated by Occlusion Balloon-Assisted Retrograde Embolization of a Coexisting Spontaneous Splenorenal Shunt

    International Nuclear Information System (INIS)

    Shioyama, Yasukazu; Matsueda, Kiyoshi; Horihata, Koushi; Kimura, Masashi; Nishida, Norifumi; Kishi, Kazushi; Terada, Masaki; Sato, Morio; Yamada, Ryusaku

    1996-01-01

    A 51-year-old man with posthepatitis cirrhosis underwent a transjugular intrahepatic portosystemic shunt (TIPS) for bleeding of recurrent esophageal varices. The patient had a coexisting, spontaneous, splenorenal shunt. He subsequently developed hepatic encephalopathy, presumably due to excessive portosystemic shunting. Since medical management resulted in no significant improvement, the splenorenal shunt was embolized from the jugular vein approach via renal vein access during temporary balloon occlusion. Within a few days, the patient's hepatic encephalopathy resolved. Twelve months later the patient showed no recurrence of encephalopathy and had maintained a patent TIPS

  8. Permanent right-to-left shunt is the key factor in managing patent foramen ovale.

    Science.gov (United States)

    Rigatelli, Gianluca; Dell'Avvocata, Fabio; Cardaioli, Paolo; Giordan, Massimo; Braggion, Gabriele; Aggio, Silvio; Chinaglia, Mauro; Mandapaka, Sangeeta; Kuruvilla, John; Chen, Jack P; Nanjundappa, Aravinda

    2011-11-15

    We sought to prospectively evaluate risk of stroke and impact of transcatheter patent foramen ovale (PFO) closure in patients with permanent right-to left shunt compared with those with Valsalva maneuver-induced right-to-left shunt. Pathophysiology and properly management of PFO still remain far from being fully clarified: in particular, the contribution of permanent right-to-left shunt remains unknown. Between March 2006 and October 2010, we enrolled 180 (mean age 44 ± 10.9 years, 98 women) of 320 consecutive patients referred to our center for transcatheter PFO closure, who had spontaneous permanent right-to-left shunt on transcranial Doppler and transthoracic/transesophageal echocardiography. All patients fulfilled the standard current indications for transcatheter closure and underwent preoperative transesophageal echocardiography and brain magnetic resonance imaging, with subsequent intracardiac echocardiographic-guided transcatheter PFO closure. We compared the clinical echocardiographic characteristics of these patients (Permanent Group) with the rest of 140 patients with right-to-left shunt only during Valsalva maneuver (Valsalva Group). Compared with the Valsalva Group patients, patients of the Permanent Group had increased frequency of multiple ischemic brain lesions on magnetic resonance imaging, previous recurrent stroke, previous peripheral arteries embolism, migraine with aura, and-more frequently-atrial septal aneurysm and prominent Eustachian valve. The presence of permanent shunt confers the highest risk of recurrent stroke (odds ratio: 5.9, 95% confidence interval: 2.0 to 12, p < 0.001). No differences were recorded between the 2 groups with regard to recurrence of ischemic events after the closure procedure. Despite its small-sample nature, our study suggests that patients with permanent right-to-left shunt have potentially a higher risk of paradoxical embolism compared with those without. Copyright © 2011 American College of Cardiology

  9. Angiography-based C-arm CT for the assessment of extrahepatic shunting before radioembolization

    International Nuclear Information System (INIS)

    Heusner, Till Alexander; Hahn, S.; Forsting, M.; Antoch, G.; Hamami, M.E.; Poeppel, T.; Bockisch, A.; Ertle, J.; Hilgard, P.

    2010-01-01

    Purpose: to retrospectively assess the accuracy of angiography-based C-arm CT for the detection of extrahepatic shunting before SIRT. Materials and methods: 30 patients (mean age: 64 ± 12 years) with hypervascularized hepatic tumors underwent hepatic angiography, coil embolization of gastrointestinal collaterals and 99mTc-macroaggregated albumin (MAA) SPECT/CT before SIRT. Before MAA injection via a microcatheter from the intended treatment position, an angiography and angiography-based C-arm CT (XperCT trademark, Philips Healthcare) were acquired. Angiographies and XperCT trademark were performed from 48 microcatheter positions followed by MAA injections and MAA-SPECT/CT. MAA-SPECT/CT served as the reference standard for determining the accuracy of hepatic arteriography and C-arm CT for the detection of extrahepatic shunting. Results: MAA-SPECT/CT revealed extrahepatic shunting in 5 patients (17%). Hepatic arteriography yielded a true negative in 22 (73%), a false negative in 5 (17%), and an unclear result in 3 patients (10%). C-arm CT yielded a true positive in 3 (10%), true negative in 24 (80%), false positive in 1 (3%), and false negative in 2 patients (7%). The specificity and the NPV of hepatic arteriography for the detection of extrahepatic shunting were 88% and 81%, respectively. For C-arm CT the sensitivity, specificity, PPV, NPV, and accuracy for the detection of extrahepatic shunting were 60%, 96%, 75%, 92%, and 90%, respectively. Conclusion: C-arm CT offers additional information to angiography when assessing SIRT patients for extrahepatic shunting. More accurate detection of extrahepatic shunting may optimize the workflow in SIRT preparations by avoiding unnecessary repeat angiographies. (orig.)

  10. CT in normal pressure hydrocephalus. Correlation between CT and clinical response to shunting

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, K.; Nogaki, H.; Noda, M.; Kusunoki, T.; Tamaki, N. (Kobe Univ. (Japan). School of Medicine)

    1981-02-01

    CT scans were obtained on 33 patients (age 73y. to 31y.) with the diagnosis of normal pressure hydrocephalus. In each case, the diagnosis was made on the basis of the symptoms, CT and cisternographic findings. Underlying diseases of normal pressure hydrocephalus are ruptured aneurysms (21 cases), arteriovenous malformations (2 cases), head trauma (1 case), cerebrovascular accidents (1 case) and idiopathie (8 cases). Sixteen of 33 patients showed marked improvement, five, moderate or minimal improvement, and twelve, no change. The results were compared with CT findings and clinical response to shunting. CT findings were classified into five types, bases on the degree of periventricular hypodensity (P.V.H.), the extent of brain damage by underlying diseases, and the degree of cortical atrophy. In 17 cases of type (I), CT shows the presence of P.V.H. with or without minimal frontal lobe damage and no cortical atrophy. The good surgical improvements were achieved in all cases of type (I) by shunting. In 4 cases of type (II), CT shows the presence of P.V.H. and severe brain damage without cortical atrophy. The fair clinical improvements were achieved in 2 cases (50%) by shunting. In one case of type (III), CT shows the absence of P.V.H. without brain damage nor cortical atrophy. No clinical improvement was obtained by shunting in this type. In 9 cases of type (IV) with mild cortical atrophy, the fair clinical improvement was achieved in two cases (22%) and no improvement in 7 cases. In 2 cases of type (V) with moderate or marked cortical atrophy, no clinical improvement was obtained by shunting. In conclusion, it appeared from the present study that there was a good correlation between the result of shunting and the type of CT, and clinical response to shunting operation might be predicted by classification of CT findings.

  11. Usefulness of a balloon-expandable, covered stent for the transjugular intrahepatic portosystemic shunt

    Directory of Open Access Journals (Sweden)

    Rössle M

    2018-01-01

    Full Text Available The availability of polytetrafluoroethylene (PTFE covered, self-expandable nitinol stents in 2001 considerably improved the patency, response rates and survival of the transjugular intrahepatic portosystemic shunt (TIPS. Side effects of portosystemic shunting such as hepatic encephalopathy (HE and worsening of hepatic function, however, remained a problem. To reduce HE, underdilatation of nitinol stents has been practiced for many years. However, as shown recently, underdilatation was a flop since, due to their intrinsic memory, nitinol stents always expanded to reach their nominal diameter of 8 or 10 mm. To overcome this problem and to be able to perform permanent shunts with a smaller diameter of < 8 mm, we studied the usefulness of a balloon-expandable, covered, metallic stent which allowed adjustment to any diameter between 5 and 12 mm. Methods: 30 patients with cirrhosis and symptomatic portal hypertension were included. The mean Child-Pugh score was 8 ± 2.17 patients had refractory ascites, 9 patients variceal bleeding and four patients other indications for the TIPS. Results: The TIPS was successfully implanted in all patients within 69.6 ± 21.8 min. The shunt reduced the portosystemic pressure gradient by 57.5 ± 14.2% with a mean stent diameter of 7.4 ± 1.0 mm (5 -10.3 mm. During a mean follow-up of 330 ± 249 days, shunt revision was necessary in 5 patients (17%, four of them had insufficient response and received stent dilatation and one patient had stent misplacement requiring a parallel shunt. Three patients (10% developed HE. Conclusions: The covered, balloon-expandable stent could be placed accurately and allowed creation of adapted shunts with smaller diameters as usual. This resulted in a comparatively low rate of HE.

  12. Association between right-to-left shunts and brain lesions in sport divers.

    Science.gov (United States)

    Gerriets, Tibo; Tetzlaff, Kay; Hutzelmann, Alfred; Liceni, Thomas; Kopiske, Gerrit; Struck, Niklas; Reuter, Michael; Kaps, Manfred

    2003-10-01

    Recent studies suggest that healthy sport divers may develop clinically silent brain damage, based on the association between a finding of multiple brain lesions on MRI and the presence of right-to-left shunt, a pathway for venous gas bubbles to enter the arterial system. We performed echocontrast transcranial Doppler sonography in 42 sport divers to determine the presence of a right-to-left shunt. Cranial MRI was carried out using a 1.5 T magnet. A lesion was counted if it was hyperintense on both T2-weighted and T2-weighted fluid attenuated inversion recovery sequences. To test the hypothesis that the occurrence of postdive arterial gas emboli is related to brain lesions on MRI, we measured postdive intravascular bubbles in a subset of 15 divers 30 min after open water scuba dives. Echocontrast transcranial Doppler sonography revealed a right-to-left shunt in 16 of the divers (38%). Only one hyperintensive lesion of the central white matter was found and that was in a diver with no evidence of a right-to-left shunt. Postdive arterial gas emboli were detected in 3 out of 15 divers; they had a right-to-left shunt, but no pathologic findings on cranial magnetic resonance imaging. Our data support the theory that right-to-left shunts can serve as a pathway for venous gas bubbles into the arterial circulation. However, we could not confirm an association between brain lesions and the presence of a right-to-left shunt in sport divers.

  13. A nonlinear plasmonic waveguide based all-optical bidirectional switching

    Science.gov (United States)

    Bana, Xiaoqiang; Pang, Xingxing; Li, Xiaohui; Hu, Bin; Guo, Yixuan; Zheng, Hairong

    2018-01-01

    In this paper, an all-optical switching with a nanometer coupled ring resonator is demonstrated based on the nonlinear material. By adjusting the light intensity, we implement the resonance wavelength from 880 nm to 940 nm in the nonlinear material structure monocyclic. In the bidirectional switch structure, the center wavelength (i.e. 880 nm) is fixed. By changing the light intensity from I = 0 to I = 53 . 1 MW /cm2, the function of optical switching can be obtained. The results demonstrate that both the single-ring cavity and the T-shaped double-ring structure can realize the optical switching effect. This work takes advantage of the simple structure. The single-ring cavity plasmonic switches have many advantages, such as nanoscale size, low pumping light intensity, ultrafast response time (femtosecond level), etc. It is expected that the proposed all-optical integrated devices can be potentially applied in optical communication, signal processing, and signal sensing, etc.

  14. Bidirectional Nonnegative Deep Model and Its Optimization in Learning

    Directory of Open Access Journals (Sweden)

    Xianhua Zeng

    2016-01-01

    Full Text Available Nonnegative matrix factorization (NMF has been successfully applied in signal processing as a simple two-layer nonnegative neural network. Projective NMF (PNMF with fewer parameters was proposed, which projects a high-dimensional nonnegative data onto a lower-dimensional nonnegative subspace. Although PNMF overcomes the problem of out-of-sample of NMF, it does not consider the nonlinear characteristic of data and is only a kind of narrow signal decomposition method. In this paper, we combine the PNMF with deep learning and nonlinear fitting to propose a bidirectional nonnegative deep learning (BNDL model and its optimization learning algorithm, which can obtain nonlinear multilayer deep nonnegative feature representation. Experiments show that the proposed model can not only solve the problem of out-of-sample of NMF but also learn hierarchical nonnegative feature representations with better clustering performance than classical NMF, PNMF, and Deep Semi-NMF algorithms.

  15. Malignant melanoma and breast carcinoma: a bidirectional correlation.

    LENUS (Irish Health Repository)

    Ho, W L

    2012-02-01

    BACKGROUND: Epidemiologic and genetic studies have suggested a bidirectional association between breast carcinoma (BC) and malignant melanoma (MM). OBSERVATION: We present a series of patients with MM and BC detected in our department within a span of 6 months, raising concerns for the high associations between the two malignancies. This led us to match the concordance of the two tumours in the National Irish Cancer Registry. CONCLUSION: The national figures provide evidence of a link between BC and MM. We recommend increased awareness among clinicians leading to more detailed surveillance of both second primary tumours. All MM patients with a family history of BC should be referred to a breast clinic. Women above the age of 40 with MM should undergo annual mammography and those less than 40 may be better evaluated with a breast MRI. All breast cancer patients should be made aware of the significance of changing moles and those with suspicious lesions referred to a dermatologist for evaluation.

  16. Malignant melanoma and breast carcinoma: a bidirectional correlation.

    LENUS (Irish Health Repository)

    Ho, W L

    2009-03-05

    BACKGROUND: Epidemiologic and genetic studies have suggested a bidirectional association between breast carcinoma (BC) and malignant melanoma (MM). OBSERVATION: We present a series of patients with MM and BC detected in our department within a span of 6 months, raising concerns for the high associations between the two malignancies. This led us to match the concordance of the two tumours in the National Irish Cancer Registry. CONCLUSION: The national figures provide evidence of a link between BC and MM. We recommend increased awareness among clinicians leading to more detailed surveillance of both second primary tumours. All MM patients with a family history of BC should be referred to a breast clinic. Women above the age of 40 with MM should undergo annual mammography and those less than 40 may be better evaluated with a breast MRI. All breast cancer patients should be made aware of the significance of changing moles and those with suspicious lesions referred to a dermatologist for evaluation.

  17. Distributed CMOS Bidirectional Amplifiers Broadbanding and Linearization Techniques

    CERN Document Server

    El-Khatib, Ziad; Mahmoud, Samy A

    2012-01-01

    This book describes methods to design distributed amplifiers useful for performing circuit functions such as duplexing, paraphrase amplification, phase shifting power splitting and power combiner applications.  A CMOS bidirectional distributed amplifier is presented that combines for the first time device-level with circuit-level linearization, suppressing the third-order intermodulation distortion. It is implemented in 0.13μm RF CMOS technology for use in highly linear, low-cost UWB Radio-over-Fiber communication systems. Describes CMOS distributed amplifiers for optoelectronic applications such as Radio-over-Fiber systems, base station transceivers and picocells; Presents most recent techniques for linearization of CMOS distributed amplifiers; Includes coverage of CMOS I-V transconductors, as well as CMOS on-chip inductor integration and modeling; Includes circuit applications for UWB Radio-over-Fiber networks.

  18. The start of lightning: Evidence of bidirectional lightning initiation.

    Science.gov (United States)

    Montanyà, Joan; van der Velde, Oscar; Williams, Earle R

    2015-10-16

    Lightning flashes are known to initiate in regions of strong electric fields inside thunderstorms, between layers of positively and negatively charged precipitation particles. For that reason, lightning inception is typically hidden from sight of camera systems used in research. Other technology such as lightning mapping systems based on radio waves can typically detect only some aspects of the lightning initiation process and subsequent development of positive and negative leaders. We report here a serendipitous recording of bidirectional lightning initiation in virgin air under the cloud base at ~11,000 images per second, and the differences in characteristics of opposite polarity leader sections during the earliest stages of the discharge. This case reveals natural lightning initiation, propagation and a return stroke as in negative cloud-to-ground flashes, upon connection to another lightning channel - without any masking by cloud.

  19. Bidirectional relationship between diabetes and periodontal disease: Review of Evidence

    International Nuclear Information System (INIS)

    Mirza, B.A.Q.; Syed, A.; Izhar, F.; Ali Khan, A.A.

    2010-01-01

    Presently there are 170 million diabetic patients worldwide. Pakistan ranks sixth in the world with approximately 6.2 million in the 20-79 year age affected by the diabetes. 6-10% of the 35-44 year old diabetic patients have been reported to be affected by moderate form of periodontal disease in Pakistan. Periodontal disease is referred to as sixth complication of diabetes. The association between diabetes and periodontal disease has been reported for more than 40 years but reverse has not been the focus of researchers until recently. Studies have suggested a bidirectional relationship between periodontal disease and glycemic control with each disease having a potential impact on the other. (author)

  20. Biophysical information in asymmetric and symmetric diurnal bidirectional canopy reflectance

    Science.gov (United States)

    Vanderbilt, Vern C.; Caldwell, William F.; Pettigrew, Rita E.; Ustin, Susan L.; Martens, Scott N.; Rousseau, Robert A.; Berger, Kevin M.; Ganapol, B. D.; Kasischke, Eric S.; Clark, Jenny A.

    1991-01-01

    The authors present a theory for partitioning the information content in diurnal bidirectional reflectance measurements in order to detect differences potentially related to biophysical variables. The theory, which divides the canopy reflectance into asymmetric and symmetric functions of solar azimuth angle, attributes asymmetric variation to diurnal changes in the canopy biphysical properties. The symmetric function is attributed to the effects of sunlight interacting with a hypothetical average canopy which would display the average diurnal properties of the actual canopy. The authors analyzed radiometer data collected diurnally in the Thematic Mapper wavelength bands from two walnut canopies that received differing irrigation treatments. The reflectance of the canopies varied with sun and view angles and across seven bands in the visible, near-infrared, and middle infrared wavelength regions. Although one of the canopies was permanently water stressed and the other was stressed in mid-afternoon each day, no water stress signature was unambiguously evident in the reflectance data.

  1. Study on bi-directional pedestrian movement using ant algorithms

    International Nuclear Information System (INIS)

    Gokce, Sibel; Kayacan, Ozhan

    2016-01-01

    A cellular automata model is proposed to simulate bi-directional pedestrian flow. Pedestrian movement is investigated by using ant algorithms. Ants communicate with each other by dropping a chemical, called a pheromone, on the substrate while crawling forward. Similarly, it is considered that oppositely moving pedestrians drop ‘visual pheromones’ on their way and the visual pheromones might cause attractive or repulsive interactions. This pheromenon is introduced into modelling the pedestrians’ walking preference. In this way, the decision-making process of pedestrians will be based on ‘the instinct of following’. At some densities, the relationships of velocity–density and flux–density are analyzed for different evaporation rates of visual pheromones. Lane formation and phase transition are observed for certain evaporation rates of visual pheromones. (paper)

  2. Bidirectional peritoneal transport of albumin in continuous ambulatory peritoneal dialysis

    DEFF Research Database (Denmark)

    Joffe, P; Henriksen, Jens Henrik Sahl

    1995-01-01

    The present study was undertaken in order to assess bidirectional peritoneal kinetics of albumin after simultaneous i.v. and i.p. injection of radioiodinated albumin tracers (125I-RISA and 131I-RISA) in eight clinically stable uraemic patients undergoing continuous ambulatory peritoneal dialysis...... (CAPD). The plasma volume, intravascular albumin mass (IVM), and overall extravasation rate of albumin were not significantly different from that found in healthy controls. Albumin flux from the plasma into the peritoneal cavity was 3.71 +/- 0.82 (SD) mumol/h, which was only 3% of the overall...... extravasation rate (137 +/- 52 mumol/h). Albumin flux from the peritoneal cavity into the plasma was substantially lower (0.22 +/- 0.07 mumol/h, P peritoneal accumulation of the albumin from plasma over 4 h was 14 +/- 3.2 mumol, which was significantly lower than the intraperitoneal albumin...

  3. Cascaded bidirectional recurrent neural networks for protein secondary structure prediction.

    Science.gov (United States)

    Chen, Jinmiao; Chaudhari, Narendra

    2007-01-01

    Protein secondary structure (PSS) prediction is an important topic in bioinformatics. Our study on a large set of non-homologous proteins shows that long-range interactions commonly exist and negatively affect PSS prediction. Besides, we also reveal strong correlations between secondary structure (SS) elements. In order to take into account the long-range interactions and SS-SS correlations, we propose a novel prediction system based on cascaded bidirectional recurrent neural network (BRNN). We compare the cascaded BRNN against another two BRNN architectures, namely the original BRNN architecture used for speech recognition as well as Pollastri's BRNN that was proposed for PSS prediction. Our cascaded BRNN achieves an overall three state accuracy Q3 of 74.38\\%, and reaches a high Segment OVerlap (SOV) of 66.0455. It outperforms the original BRNN and Pollastri's BRNN in both Q3 and SOV. Specifically, it improves the SOV score by 4-6%.

  4. Bi-directional associations between psychological arousal, cortisol, and sleep

    DEFF Research Database (Denmark)

    Garde, Anne Helene; Albertsen, Karen; Persson, Roger

    2012-01-01

    The aim was to elucidate the possible bi-directional relation between daytime psychological arousal, cortisol, and self-reported sleep in a group of healthy employees in active employment. Logbook ratings of sleep (Karolinska Sleep Questionnaire), stress, and energy, as well as positive...... and negative experiences in work and private life, were collected together with salivary cortisol over 3 days (n = 265). Higher bedtime ratings of stress and problems during the day were associated with morning ratings of poor sleep. Poorer morning ratings of sleep were associated with higher ratings of stress...... and problems during the day. The results underpin the possibility that arousal and poor sleep might create a self-reinforcing vicious circle that negatively affects a person's well-being....

  5. Model of bidirectional reflectance distribution function for metallic materials

    International Nuclear Information System (INIS)

    Wang Kai; Zhu Jing-Ping; Liu Hong; Hou Xun

    2016-01-01

    Based on the three-component assumption that the reflection is divided into specular reflection, directional diffuse reflection, and ideal diffuse reflection, a bidirectional reflectance distribution function (BRDF) model of metallic materials is presented. Compared with the two-component assumption that the reflection is composed of specular reflection and diffuse reflection, the three-component assumption divides the diffuse reflection into directional diffuse and ideal diffuse reflection. This model effectively resolves the problem that constant diffuse reflection leads to considerable error for metallic materials. Simulation and measurement results validate that this three-component BRDF model can improve the modeling accuracy significantly and describe the reflection properties in the hemisphere space precisely for the metallic materials. (paper)

  6. Model of bidirectional reflectance distribution function for metallic materials

    Science.gov (United States)

    Wang, Kai; Zhu, Jing-Ping; Liu, Hong; Hou, Xun

    2016-09-01

    Based on the three-component assumption that the reflection is divided into specular reflection, directional diffuse reflection, and ideal diffuse reflection, a bidirectional reflectance distribution function (BRDF) model of metallic materials is presented. Compared with the two-component assumption that the reflection is composed of specular reflection and diffuse reflection, the three-component assumption divides the diffuse reflection into directional diffuse and ideal diffuse reflection. This model effectively resolves the problem that constant diffuse reflection leads to considerable error for metallic materials. Simulation and measurement results validate that this three-component BRDF model can improve the modeling accuracy significantly and describe the reflection properties in the hemisphere space precisely for the metallic materials.

  7. Bidirectional microwave-mechanical-optical transducer in a dilution refrigerator

    Science.gov (United States)

    Burns, Peter S.; Higginbotham, Andrew P.; Peterson, Robert W.; Urmey, Maxwell D.; Kampel, Nir S.; Menke, Timothy; Cicak, Katarina; Simmonds, Raymond. W.; Regal, Cindy A.; Lehnert, Konrad W.

    Transferring quantum states between microwave and optical networks would be a powerful resource for quantum communication and computation. Our approach is to simultaneously couple one mode of a micromechanical oscillator to a resonant microwave circuit and a high-finesse optical cavity. Building on previous work demonstrating bidirectional and efficient classical conversion at 4 K, a new microwave-to-optical transducer is operated at 0.1 K and preparations are underway to operate it in the quantum regime. To improve transfer efficiency, we characterize and implement wireless microwave access to the converter chip. Transfer efficiency of the device is measured, and loss in the LC circuit due to laser light is characterized. We acknowledge support from AFOSR MURI Grant FA9550-15-1-0015 and PFC National Science Foundation Grant 1125844.

  8. Bidirectional Cardio-Respiratory Interactions in Heart Failure

    Directory of Open Access Journals (Sweden)

    Nikola N. Radovanović

    2018-03-01

    Full Text Available We investigated cardio-respiratory coupling in patients with heart failure by quantification of bidirectional interactions between cardiac (RR intervals and respiratory signals with complementary measures of time series analysis. Heart failure patients were divided into three groups of twenty, age and gender matched, subjects: with sinus rhythm (HF-Sin, with sinus rhythm and ventricular extrasystoles (HF-VES, and with permanent atrial fibrillation (HF-AF. We included patients with indication for implantation of implantable cardioverter defibrillator or cardiac resynchronization therapy device. ECG and respiratory signals were simultaneously acquired during 20 min in supine position at spontaneous breathing frequency in 20 healthy control subjects and in patients before device implantation. We used coherence, Granger causality and cross-sample entropy analysis as complementary measures of bidirectional interactions between RR intervals and respiratory rhythm. In heart failure patients with arrhythmias (HF-VES and HF-AF there is no coherence between signals (p < 0.01, while in HF-Sin it is reduced (p < 0.05, compared with control subjects. In all heart failure groups causality between signals is diminished, but with significantly stronger causality of RR signal in respiratory signal in HF-VES. Cross-sample entropy analysis revealed the strongest synchrony between respiratory and RR signal in HF-VES group. Beside respiratory sinus arrhythmia there is another type of cardio-respiratory interaction based on the synchrony between cardiac and respiratory rhythm. Both of them are altered in heart failure patients. Respiratory sinus arrhythmia is reduced in HF-Sin patients and vanished in heart failure patients with arrhythmias. Contrary, in HF-Sin and HF-VES groups, synchrony increased, probably as consequence of some dominant neural compensatory mechanisms. The coupling of cardiac and respiratory rhythm in heart failure patients varies depending on the

  9. Bidirectional Cardio-Respiratory Interactions in Heart Failure.

    Science.gov (United States)

    Radovanović, Nikola N; Pavlović, Siniša U; Milašinović, Goran; Kirćanski, Bratislav; Platiša, Mirjana M

    2018-01-01

    We investigated cardio-respiratory coupling in patients with heart failure by quantification of bidirectional interactions between cardiac (RR intervals) and respiratory signals with complementary measures of time series analysis. Heart failure patients were divided into three groups of twenty, age and gender matched, subjects: with sinus rhythm (HF-Sin), with sinus rhythm and ventricular extrasystoles (HF-VES), and with permanent atrial fibrillation (HF-AF). We included patients with indication for implantation of implantable cardioverter defibrillator or cardiac resynchronization therapy device. ECG and respiratory signals were simultaneously acquired during 20 min in supine position at spontaneous breathing frequency in 20 healthy control subjects and in patients before device implantation. We used coherence, Granger causality and cross-sample entropy analysis as complementary measures of bidirectional interactions between RR intervals and respiratory rhythm. In heart failure patients with arrhythmias (HF-VES and HF-AF) there is no coherence between signals ( p respiratory signal in HF-VES. Cross-sample entropy analysis revealed the strongest synchrony between respiratory and RR signal in HF-VES group. Beside respiratory sinus arrhythmia there is another type of cardio-respiratory interaction based on the synchrony between cardiac and respiratory rhythm. Both of them are altered in heart failure patients. Respiratory sinus arrhythmia is reduced in HF-Sin patients and vanished in heart failure patients with arrhythmias. Contrary, in HF-Sin and HF-VES groups, synchrony increased, probably as consequence of some dominant neural compensatory mechanisms. The coupling of cardiac and respiratory rhythm in heart failure patients varies depending on the presence of atrial/ventricular arrhythmias and it could be revealed by complementary methods of time series analysis.

  10. Bidirectional Association between Depression and Type 2 Diabetes in Women

    Science.gov (United States)

    Pan, An; Lucas, Michel; Sun, Qi; van Dam, Rob M.; Franco, Oscar H.; Manson, JoAnn E.; Willett, Walter C.; Ascherio, Alberto; Hu, Frank B.

    2011-01-01

    Background Although it has been hypothesized that the diabetes-depression relation is bidirectional, few studies have addressed this hypothesis in a prospective setting. Methods A total of 65381 women aged 50–75 years in 1996 were followed until 2006. Clinical depression was defined as having diagnosed depression or using antidepressants, and depressed mood was defined as having clinical depression or severe depressive symptomatology, i.e., a Mental Health Index (MHI-5) score ≤52. Self-reported type 2 diabetes was confirmed using a supplementary questionnaire validated by medical record review. Results During 10-year follow-up (531097 person-years), 2844 incident cases of type 2 diabetes were documented. Compared to referents (MHI-5 score 86–100) who had the least depressive symptomatology, participants with increased severity of symptoms (MHI-5 score 76–85, 53–75, depressed mood) showed a monotonic elevated risk of developing type 2 diabetes (P for trend = 0.002). The relative risk (RR) for individuals with depressed mood was 1.17 (95% confidence interval [CI], 1.05–1.30) after adjustment for various covariates, and participants using antidepressants were at a particularly higher risk (RR, 1.25; 95% CI, 1.10–1.41). In a parallel analysis, 7415 incident clinical depression were documented (474722 person-years). Compared to non-diabetics, the RRs of developing clinical depression after controlling for all covariates were 1.29 (95% CI, 1.18–1.40) for diabetic patients, and 1.25, 1.24, 1.53 in diabetics without medications, with oral hypoglycemic agents, and insulin therapy, respectively (all P<0.01). These associations remained significant after adjustment for diabetes-related comorbidities. Conclusions Our results provide compelling evidence that the diabetes-depression association is bidirectional. PMID:21098346

  11. BiPOD Arthroscopic Acromioclavicular Repair Restores Bidirectional Stability.

    Science.gov (United States)

    De Beer, Joe; Schaer, Michael; Latendresse, Kim; Raniga, Sumit; Moor, Beat K; Zumstein, Matthias A

    2017-01-01

    Stabilizing the acromioclavicular joint in the vertical and horizontal planes is challenging, and most current techniques do not reliably achieve this goal. The BiPOD repair is an arthroscopically assisted procedure performed with image intensifier guidance that reconstructs the coracoclavicular ligaments as well as the acromioclavicular ligaments to achieve bidirectional stability. Repair is achieved with a combination of 2-mm FiberTape (Arthrex, Naples, Florida) and 20-mm Poly-Tape (Neoligaments, Leeds, England) to achieve rigid repair, prevent bone abrasion, and promote tissue ingrowth. This study is a prospective review of the first 6 patients treated for high-grade acute acromioclavicular injury with the BiPOD technique. The study included 6 men who were 21 to 36 years old (mean, 27 years). At 6-month follow-up, complications were recorded and radiographic analysis was used to determine the coracoclavicular distance for vertical reduction and the amount of acromioclavicular translation on the Alexander axillary view was used to determine horizontal reduction. One patient had a superficial infection over the tape knot. The difference in coracoclavicular distance between the operated side and the uninvolved side was 9±2 mm preoperatively and 0.3±2 mm at 6-month follow-up. On Alexander axillary view, all 6 patients showed stable reduction, which is defined as a clavicle that is in line with the acromion. The findings show that BiPOD acromioclavicular reconstruction restores bidirectional stability of the acromioclavicular joint at 6 months. [Orthopedics. 2017; 40(1):e35-e43.]. Copyright 2016, SLACK Incorporated.

  12. Reproducibility of right-to-left shunt quantification using transthoracic contrast echocardiography in hereditary haemorrhagic telangiectasia.

    Science.gov (United States)

    Vorselaars, V M M; Velthuis, S; Huitema, M P; Hosman, A E; Westermann, C J J; Snijder, R J; Mager, J J; Post, M C

    2018-04-01

    Transthoracic contrast echocardiography (TTCE) is recommended for screening of pulmonary arteriovenous malformations (PAVMs) in hereditary haemorrhagic telangiectasia. Shunt quantification is used to find treatable PAVMs. So far, there has been no study investigating the reproducibility of this diagnostic test. Therefore, this study aimed to describe inter-observer and inter-injection variability of TTCE. We conducted a prospective single centre study. We included all consecutive persons screened for presence of PAVMs in association with hereditary haemorrhagic telangiectasia in 2015. The videos of two contrast injections per patient were divided and reviewed by two cardiologists blinded for patient data. Pulmonary right-to-left shunts were graded using a three-grade scale. Inter-observer and inter-injection agreement was calculated with κ statistics for the presence and grade of pulmonary right-to-left shunts. We included 107 persons (accounting for 214 injections) (49.5% male, mean age 45.0 ± 16.6 years). A pulmonary right-to-left shunt was present in 136 (63.6%) and 131 (61.2%) injections for observer 1 and 2, respectively. Inter-injection agreement for the presence of pulmonary right-to-left shunts was 0.96 (95% confidence interval (CI) 0.9-1.0) and 0.98 (95% CI 0.94-1.00) for observer 1 and 2, respectively. Inter-injection agreement for pulmonary right-to-left shunt grade was 0.96 (95% CI 0.93-0.99) and 0.95 (95% CI 0.92-0.98) respectively. There was disagreement in right-to-left shunt grade between the contrast injections in 11 patients (10.3%). Inter-observer variability for presence and grade of the pulmonary right-to-left shunt was 0.95 (95% CI 0.91-0.99) and 0.97 (95% CI 0.95-0.99) respectively. TTCE has an excellent inter-injection and inter-observer agreement for both the presence and grade of pulmonary right-to-left shunts.

  13. A modified Glenn shunt reduces right ventricular stroke work during left ventricular assist device therapy.

    Science.gov (United States)

    Schiller, Petter; Vikholm, Per; Hellgren, Laila

    2016-03-01

    Right ventricular (RV) failure is a major cause of morbidity and mortality after left ventricular assist device (LVAD) placement and remains hard to predict. We hypothesized that partial surgical exclusion of the RV with a modified Glenn shunt during LVAD treatment would reduce RV stroke work. An LVAD was implanted in eight pigs and a modified Glenn shunt was constructed. A conductance pressure-volume catheter was placed in the right ventricle through the apex. Haemodynamic data and pressure-volume loops were obtained at the following time periods: (i) baseline, (ii) open shunt, (iii) LVAD with closed shunt and (iii) LVAD and open shunt. During LVAD therapy, the right atrial (RA) pressure increased from 9 mmHg (9-9) to 15 mmHg (12-15), P = 0.01. RV stroke volume increased from 30 ml (29-40) to 51 ml (42-53), P work increased to 708 mmHg ml (654-1193) from 535 mmHg ml (424-717), P = 0.04, compared with baseline. During LVAD therapy in combination with a Glenn shunt, the RA pressure decreased from 15 mmHg (12-15) to 10 mmHg (7-11) when compared with LVAD therapy only, P = 0.01. A decrease in RV stroke work from 708 mmHg ml (654-1193) to 465 mmHg ml (366-711), P = 0.04, was seen when the LVAD was combined with a shunt, not significantly different from the baseline value (535 mmHg ml). The developed pressure in the right ventricle decreased from 29 mmHg (26-32) to 21 mmHg (20-24), P work during the use of the shunt with LVAD treatment. A modified Glenn shunt reduced RV volumes, RV stroke work and RA pressure during LVAD therapy in an experimental model of heart failure in pigs. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  14. Impact of cerebrospinal fluid shunting for idiopathic normal pressure hydrocephalus on the amyloid cascade.

    Directory of Open Access Journals (Sweden)

    Masao Moriya

    Full Text Available The aim of this study was to determine whether the improvement of cerebrospinal fluid (CSF flow dynamics by CSF shunting, can suppress the oligomerization of amyloid β-peptide (Aβ, by measuring the levels of Alzheimer's disease (AD-related proteins in the CSF before and after lumboperitoneal shunting. Lumbar CSF from 32 patients with idiopathic normal pressure hydrocephalus (iNPH (samples were obtained before and 1 year after shunting, 15 patients with AD, and 12 normal controls was analyzed for AD-related proteins and APLP1-derived Aβ-like peptides (APL1β (a surrogate marker for Aβ. We found that before shunting, individuals with iNPH had significantly lower levels of soluble amyloid precursor proteins (sAPP and Aβ38 compared to patients with AD and normal controls. We divided the patients with iNPH into patients with favorable (improvement ≥ 1 on the modified Rankin Scale and unfavorable (no improvement on the modified Rankin Scale outcomes. Compared to the unfavorable outcome group, the favorable outcome group showed significant increases in Aβ38, 40, 42, and phosphorylated-tau levels after shunting. In contrast, there were no significant changes in the levels of APL1β25, 27, and 28 after shunting. After shunting, we observed positive correlations between sAPPα and sAPPβ, Aβ38 and 42, and APL1β25 and 28, with shifts from sAPPβ to sAPPα, from APL1β28 to 25, and from Aβ42 to 38 in all patients with iNPH. Our results suggest that Aβ production remained unchanged by the shunt procedure because the levels of sAPP and APL1β were unchanged. Moreover, the shift of Aβ from oligomer to monomer due to the shift of Aβ42 (easy to aggregate to Aβ38 (difficult to aggregate, and the improvement of interstitial-fluid flow, could lead to increased Aβ levels in the CSF. Our findings suggest that the shunting procedure can delay intracerebral deposition of Aβ in patients with iNPH.

  15. Chatter reduction in boring process by using piezoelectric shunt damping with experimental verification

    Science.gov (United States)

    Yigit, Ufuk; Cigeroglu, Ender; Budak, Erhan

    2017-09-01

    Chatter is a self-excited type of vibration that develops during machining due to process-structure dynamic interactions resulting in modulated chip thickness. Chatter is an important problem as it results in poor surface quality, reduced productivity and tool life. The stability of a cutting process is strongly influenced by the frequency response function (FRF) at the cutting point. In this study, the effect of piezoelectric shunt damping on chatter vibrations in a boring process is studied. In piezoelectric shunt damping method, an electrical impedance is connected to a piezoelectric transducer which is bonded on cutting tool. Electrical impedance of the circuit consisting of piezoceramic transducer and passive shunt is tuned to the desired natural frequency of the cutting tool in order to maximize damping. The optimum damping is achieved in analytical and finite element models (FEM) by using a genetic algorithm focusing on the real part of the tool point FRF rather than the amplitude. Later, a practical boring bar is considered where the optimum circuit parameters are obtained by the FEM. Afterwards, the effect of the optimized piezoelectric shunt damping on the dynamic rigidity and absolute stability limit of the cutting process are investigated experimentally by modal analysis and cutting tests. It is both theoretically and experimentally shown that application of piezoelectric shunt damping results in a significant increase in the absolute stability limit in boring operations.

  16. Comparison of series regulated neutral beam accel supplies with shunt regulated accel supplies

    International Nuclear Information System (INIS)

    Baker, W.; Smith, B.H.

    1976-01-01

    This study was undertaken to get a direct comparison between comparable series and shunt regulated power supplies. It is intended that the two supplies will be strictly equivalent with the same safety factors in the design of each type and the cost estimates made on the same basis. The series regulated power supply is simply a scaled up version of the 2XIIB Accel Supplies. Each supply provides 150 kV, 65 ampere, 500 ms pulse output such as will be used on the TFTR sources. The shunt regulated power supply uses high reactance transformers to provide the series impedance for the shunt regulator. The most significant difference in the performance of the two types of power supplies is that the shunt regulated supply has a minimum interrupt period of 16 ms, whereas the series regulated supply can have about 0.5 ms. Even this difference can be eliminated with a commutator circuit such as is being developed in Berkeley for the 150 kV, 20 ampere system. The 16 ms period is probably not a very serious limitation because it still permits up to 31 interrupts per 500 ms pulse. The shunt regulated system appears to be about 37 percent less expensive than the series system

  17. Right Lower Quadrant Abdominal Pain in a Patient with Prior Ventriculoperitoneal Shunting: Consider the Tip!

    Directory of Open Access Journals (Sweden)

    Petros Charalampoudis

    2012-01-01

    Full Text Available Introduction. Ventriculoperitoneal (VP shunting is the treatment of choice for nonobstructive hydrocephalus. In patients with such a device, right lower quadrant abdominal pain can puzzle the surgeon, posing a differential diagnostic problem among appendicitis, nonsurgical colicky pain, and primary shunt catheter tip infection. Treatment is different in either case. Presentation of Case. We hereby present a case of a young woman with prior ventriculoperitoneal shunt positioning who presented to our department with right lower quadrant abdominal pain. The patient underwent a 24-hour observation including a neurosurgery consult in order to exclude acute appendicitis and VP shunt tip infection. Twenty four hours later, the patient’s symptomatology improved, and she was discharged with the diagnosis of atypical colicky abdominal pain seeking a gastroenterologist consult. Discussion. This case supports that when a patient with prior VP shunting presents with right lower quadrant abdominal pain, differential diagnosis can be tricky for the surgeon. Conclusion. Apart from acute appendicitis, primary or secondary VP catheter tip infection must be considered because the latter can be disastrous.

  18. Radionuclide cisternography in diagnostics of obstruction hydrocephalus in introduced ventricculoperitoneal shunt

    International Nuclear Information System (INIS)

    Cernochova, I.; Lipina, R.

    2004-01-01

    To confirm or exclude a diagnosis of internal obstruction hydrocephalus in an 8-year old girl with an introduced ventriculoperitoneal (V-P) shunt Establishing the V-P shunt is indisputably the route of choice in non-communicating hydrocephalus. The existence of a V-P shunt, however, is connected with numerous risks, especially of injuries, infection as well as increased intraabdominal pressure - e.g. in pregnancy. The development of endoscopy in neurosurgery allows the creation of communication via the bottom of the third ventricle with basal cisterns, and the subsequent cancellation of a V-P shunt. We describe the case of an 8-year old girl with congenital internal hydrocephalus with an assumed obliteration of the Sylvian aqueduct with an established V-P shunt. An MR scan described the membrane in the area of the Sylvian aqueduct, but the disproportion between the dilatation of the lateral ventricles, third ventricle and fourth ventricle led the physician to doubt as to the accuracy of the diagnosis of internal obstruction hydrocephalus. Therefore we performed a radionuclide cisternography (in a modified manner), which proved an existing communication between the third and fourth cerebral ventricle and which contradicted the clinical diagnosis of obstruction hydrocephalus. (author)

  19. [A case of non-traumatic tension pneumocephalus 12 years after initial ventriculo-peritoneal shunt].

    Science.gov (United States)

    Idei, Masaru; Yamane, Kanji; Okita, Shinji; Kumano, Kiyoshi; Nakae, Ryuta; Nishizawa, Shigeru

    2009-10-01

    The authors presented a patient with non-traumatic tension pneumocephalus 12 years after initial ventriculo-peritoneal shunt. A 60-year-old man had a past history of subarachnoid hemorrhage. At ÿtime, he underwent clipping surgery and emplacement of a ventriculoperitoneal shunt with a low pressure valve, and was discharged from hospital in a bedridden condition. After 12 years, he was transferred to our hospital because of dysarthria and right hemiparesis. On admission, he had multiple dimples of the scalp in the left frontal area where craniotomy had been carried out 12 years before. Head CT scan revealed air located mainly in bilateral subdural space and collapsed ventricles. We suspected that he had a tension pneumocephalus through a scalp-subdural fistula induced by long-term low intracranial pressure. Operation for closure of the fistula was intended. During the operation a subdural abscess was found so, artificial bone and the shunt system was removed. We were able to detect the fistula from the defect of the scalp to the subdural space and closed it by repairing a scalp defect, using dural plasty. Postoperative clinical course was uneventful and the patient was discharged. About 6 month after the operation, cranioplasty and lumbo-peritoneal shunt was performed. We must recognize that appropriate management of intracranial pressure after installation of a ventriculo-peritoneal shunt is necessary for prevention of tension pneumocephalus.

  20. Hypoxia and GABA shunt activation in the pathogenesis of Alzheimer's disease.

    Science.gov (United States)

    Salminen, Antero; Jouhten, Paula; Sarajärvi, Timo; Haapasalo, Annakaisa; Hiltunen, Mikko

    2016-01-01

    We have previously observed that the conversion of mild cognitive impairment to definitive Alzheimer's disease (AD) is associated with a significant increase in the serum level of 2,4-dihydroxybutyrate (2,4-DHBA). The metabolic generation of 2,4-DHBA is linked to the activation of the γ-aminobutyric acid (GABA) shunt, an alternative energy production pathway activated during cellular stress, when the function of Krebs cycle is compromised. The GABA shunt can be triggered by local hypoperfusion and subsequent hypoxia in AD brains caused by cerebral amyloid angiopathy. Succinic semialdehyde dehydrogenase (SSADH) is a key enzyme in the GABA shunt, converting succinic semialdehyde (SSA) into succinate, a Krebs cycle intermediate. A deficiency of SSADH activity stimulates the conversion of SSA into γ-hydroxybutyrate (GHB), an alternative route from the GABA shunt. GHB can exert not only acute neuroprotective activities but unfortunately also chronic detrimental effects which may lead to cognitive impairment. Subsequently, GHB can be metabolized to 2,4-DHBA and secreted from the brain. Thus, the activation of the GABA shunt and the generation of GHB and 2,4-DHBA can have an important role in the early phase of AD pathogenesis. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Prevalence of patent foramen ovale with right-to-left shunting in dogs with pulmonic stenosis.

    Science.gov (United States)

    Fujii, Y; Nishimoto, Y; Sunahara, H; Takano, H; Aoki, T

    2012-01-01

    Right-to-left (R-L) shunt caused by patent foramen ovale (PFO) concurrent with pulmonic stenosis (PS) is considered common, although there is a lack of published evidence. To investigate the prevalence of R-L shunt caused by a PFO in dogs with PS. Thirty-one client-owned dogs with PS, without obvious extracardiac disease detected on the clinical examinations. Case control study: R-L shunt probably caused by PFO was diagnosed when IV injected microbubbles appeared at the left atrial level with an intact atrial septum on echocardiography (bubble-positive dogs). The severity of PS concurrent tricuspid regurgitation (TR), relative thickness of the right ventricle, and relative right atrial area were compared between bubble-positive and bubble-negative dogs. The prevalence of R-L shunts caused by PFO was 39% (12 of 31 cases). The instantaneous pressure gradient (PG) across the pulmonic valve and relative thickness of the right ventricle were significantly increased in bubble-positive compared with those in bubble-negative dogs. None of the dogs with mild or moderate PS (pressure gradient dogs was significantly higher than that in bubble-negative dogs. DISCUSSION AND CLINICAL RELEVANCE: Patent foramen ovale PFO with R-L shunt was more common in dogs with very severe PS and absent in dogs with mild PS. Copyright © 2011 by the American College of Veterinary Internal Medicine.

  2. Usefulness of color and pulsed Doppler's in the evaluation of surgical portosystemic shunts in pediatric patients

    International Nuclear Information System (INIS)

    Berrocal, T.; Prieto, C.; Cortes, P.; Rodriguez, R.; Pastor, I.

    2003-01-01

    Portosystemic shunts are performed to relieve symptomatic portal hypertension symptomatic or removal pressure in hepatic vascularisation in patients with Budd-Chiari's syndrome. Most surgical portosystemic shunts can be suitably studied by means of ultrasound scan complemented by color and pulsed Dopplers, proved one understands the hemodynamics of the surgical procedures involved. This article demonstrates the usefulness and limitations of the ultrasound scan Duplex Doppler in the evaluation of portosystemic shunts performed on pediatric patients. Pulsed Doppler provides information regarding the nature and direction of blood flow. Color doppler is capable of directly revealing the shunt and, in most cases, permits the anastomosis to be located. The types of shunts that appear include proximal and distal spleno-renal, portocaval and mesocaval. Types of vascular connections are illustrated,s well as expected post-surgical blood flow direction in affected vessels. The ultrasound scanning technique is discussed, as well as the criteria for determining vascular permeability. Also highlighted are the advantages, limitations and diagnostic difficulties associated with the different forms of Doppler. (Author) 17 refs

  3. Bi-directional charger for swiss2G - Annual report; Bi-directional charger for swiss2G - Jahresbericht

    Energy Technology Data Exchange (ETDEWEB)

    Schwab, M.; Baumann, P.

    2010-11-15

    This short annual report for 2010 for the Swiss Federal Office of Energy (SFOE) takes a look at a bi-directional charger that can be used in intelligent 'Smart Grid' applications. The idea is based on being able to use electric vehicles as a source of electricity to help meet peak demand for mains electricity. The swiss2G project aims to produce an electric car battery-charger that also functions as an inverter to convert the car's DC battery voltage to mains electricity. The project was started in September 2010. The report describes the aims of the project and reports on initial work done in the areas of safety, switching electronics and AC/DC conversion. National and international co-operation is noted and prospects for further work are discussed.

  4. Preoperative MR angiography evaluation of transjugular intrahepatic portosystemic shunt

    International Nuclear Information System (INIS)

    Guo Li; Yang Dakuan; Yuan Shuguang; Yan Dong; Wang Jiaping; Li Yingchun

    2010-01-01

    Objective: To discuss the application of MR angiography (MRA) in deciding the puncture points of transjugular intrahepatic portosystemic shunt (TIPS). Methods: Preoperative MRA was performed in 59 patients with portal hypertension (study group) in order to search for the causes of portal hypertension, to observe the patterns and route of the hepatic and portal veins and to measure the vascular diameter at the scheduled puncture site. MRA was also performed in 50 healthy subjects, which was served as the control group. The results were compared between two groups. Results: The diseases in the study group included simple cirrhosis (n=49), cirrhosis accompanied with hepatocellular carcinoma (n=4), pure portal vein thrombosis (n=3), splenic vein stenosis (n=1) and Budd-Chiari syndrome (n=2). In study group the type I, II and III of the hepatic vein classification were seen in 14, 39 and 12 cases respectively,while in control group in 12, 34 and 14 cases respectively. In study group, the right, middle and left hepatic vein which had the diameter larger enough for puncturing existed in 52, 40 and 28 cases respectively, while in control group in 46, 34 and 23 cases respectively. The safe point for puncture via the right and the left branch of the portal vein was located beyond the distance of (16.2 ± 3.1) mm and (14.2 ± 3.8) mm respectively. Conclusion: MRA is a valuable non-invasive examination, which is of great value in determining the causes of portal hypertension and in planning the puncturing sites before performing TIPS. (authors)

  5. Nickel elution properties of contemporary interatrial shunt closure devices.

    Science.gov (United States)

    Verma, Divya Ratan; Khan, Muhammad F; Tandar, Anwar; Rajasekaran, Namakkal S; Neuharth, Renée; Patel, Amit N; Muhlestein, Joseph B; Badger, Rodney S

    2015-02-01

    We sought to compare nickel elution properties of contemporary interatrial shunt closure devices in vitro. There are two United States Food and Drug Administration (FDA)-approved devices for percutaneous closure of secundum atrial septal defect: the Amplatzer septal occluder (ASO; St Jude Medical Corporation) and Gore Helex septal occluder (HSO; W.L. Gore & Associates). The new Gore septal occluder (GSO) device is in clinical trials. These are also used off-label for patent foramen ovale closure in highly selected patients. These devices have high nickel content. Nickel allergy is the most common reason for surgical device explantation. Nickel elution properties of contemporary devices remain unknown. We compared nickel elution properties of 4 devices - ASO, GSO, HSO, and sternal wire (SW) - while Dulbecco's phosphate-buffered saline (DPBS) served as control. Three samples of each device were submerged in DPBS. Nickel content was measured at 14 intervals over 90 days. Nickel elution at 24 hours, compared to control (0.005 ± 0.0 mg/L), was significantly higher for ASO (2.98 ± 1.65 mg/L; P=.04) and SW (0.03 ± 0.014 mg/L; P=.03). Nickel levels at 90 days, compared to control (0.005 ± 0.0 mg/L) and adjusting for multiple comparisons, were significantly higher for ASO (19.80 ± 2.30 mg/L; P=.01) and similar for HSO (P=.34), GSO (P=.34), and SW (P=.34). ASO had significantly higher nickel elution compared to HSO, GSO, and SW (P=.01). There is substantial variability in nickel elution; devices with less exposed nickel (HSO and GSO) have minimal elution. The safety of low nickel elution devices in patients with nickel allergy needs to be evaluated in prospective trials.

  6. Model based feasibility study on bidirectional check valves in wave energy converters

    DEFF Research Database (Denmark)

    Hansen, Anders Hedegaard; Pedersen, Henrik C.; Andersen, Torben Ole

    2014-01-01

    Discrete fluid power force systems have been proposed as the primary stage for Wave Energy Converters (WEC’s) when converting ocean waves into electricity, this to improve the overall efficiency of wave energy devices. This paper presents a model based feasibility study of using bidirectional check....../Off and bidirectional check valves. Based on the analysis it is found that the energy production may be slightly improved by using bidirectional check valves as compared to on/off valves, due to a decrease in switching losses. Furthermore a reduction in high flow peaks are realised. The downside being increased...

  7. A New Bi-Directional Projection Model Based on Pythagorean Uncertain Linguistic Variable

    Directory of Open Access Journals (Sweden)

    Huidong Wang

    2018-04-01

    Full Text Available To solve the multi-attribute decision making (MADM problems with Pythagorean uncertain linguistic variable, an extended bi-directional projection method is proposed. First, we utilize the linguistic scale function to convert uncertain linguistic variable and provide a new projection model, subsequently. Then, to depict the bi-directional projection method, the formative vectors of alternatives and ideal alternatives are defined. Furthermore, a comparative analysis with projection model is conducted to show the superiority of bi-directional projection method. Finally, an example of graduate’s job option is given to demonstrate the effectiveness and feasibility of the proposed method.

  8. The Topologies Research of a Soft Switching Bidirectional DC/DC Converter

    DEFF Research Database (Denmark)

    Zhang, Qi; Zhang, Yongping; Sun, Xiangdong

    2017-01-01

    A soft-switching solution implemented to the traditional bidirectional DC/DC converter is developed. The soft-switching cell, which composed of three auxiliary switches, one resonant capacitor and one resonant inductor, is equipped in the traditional bidirectional DC/DC converter to realize circuit...... circle. And the proposed topology of bidirectional soft-switching dc-dc converter(TASBC) performs ideal soft switching at boost operations. The characteristics of the proposed converter has been verified by MATLAB simulations and experimental results....

  9. Framewise phoneme classification with bidirectional LSTM and other neural network architectures.

    Science.gov (United States)

    Graves, Alex; Schmidhuber, Jürgen

    2005-01-01

    In this paper, we present bidirectional Long Short Term Memory (LSTM) networks, and a modified, full gradient version of the LSTM learning algorithm. We evaluate Bidirectional LSTM (BLSTM) and several other network architectures on the benchmark task of framewise phoneme classification, using the TIMIT database. Our main findings are that bidirectional networks outperform unidirectional ones, and Long Short Term Memory (LSTM) is much faster and also more accurate than both standard Recurrent Neural Nets (RNNs) and time-windowed Multilayer Perceptrons (MLPs). Our results support the view that contextual information is crucial to speech processing, and suggest that BLSTM is an effective architecture with which to exploit it.

  10. Design of PI Controlled Non Isolated Bidirectional DC to DC Converter for Electric Vehicle Application

    Science.gov (United States)

    Geetha, A.; Subramani, C.; Thamizh Thentral, T. M.; Krithika, V.; Usha, S.

    2018-04-01

    Non isolated Bidirectional DC-DC Converter (NIBDDC) is a good interface between DC source and inverter Fed induction motor drive. This paper deals with comparison between open loop and PI controlled Bidirectional DC to DC Converter Inverter System (BDDCIS). The modelling and control of BDDC is becomes an important issue. Open loop BDDCIS and closed loop PI controlled BDDCIS are designed, modelled and simulated using Matlab- simulink and their results are presented. The investigations indicate superior performance of PI controlled BDDCIS. The proposed BDDCIS has advantages like bidirectional power transfer ability, reduced hardware count and improved dynamic response.

  11. Phase Locking and Chaos in a Josephson Junction Array Shunted by a Common Resistance

    International Nuclear Information System (INIS)

    Tie-Ge, Zhou; Jing, Mao; Ting-Shu, Liu; Yue, Lai; Shao-Lin, Yan

    2009-01-01

    The dynamics of a Josephson junction array shunted by a common resistance are investigated by using numerical methods. Coexistence of phase locking and chaos is observed in the system when the resistively and capacitively shunted junction model is adopted. The corresponding parameter ranges for phase locking and chaos are presented. When there are three resistively shunted junctions in the array, chaos is found for the first time and the parameter range for chaos is also presented. According to the theory of Chernikov and Schmidt, when there are four or more junctions in the array, the system exhibits chaotic behavior. Our results indicate that the theory of Chernikov and Schmidt is not exactly appropriate. (condensed matter: electronicstructure, electrical, magnetic, and opticalproperties)

  12. Diagnostic imagings and embolotherapy for the superior mesenteric vein-inferior vena cava shunt

    International Nuclear Information System (INIS)

    Morita, Yutaka; Yamada, Masataka; Miyata, Mutsuhiko; Kubo, Kohzo.

    1994-01-01

    Diagnostic imaging and embolization therapy for the uncommon portal and mesenteric vein-inferior vena cave shunt (PV·SMV-IVC shunt) are reported. As the frequency of clinical symptoms such as hematemesis, melena and confusion caused by gastrointestinal varices, or hepatoencephalopathy was about 40%, it was important for this disease entity to be diagnosed with noninvasive diagnostic images. The careful examination of the area around the right renal vein was able to overcome the low diagnostic rate of 20-40% obtained with US and CT images. In cases of simple PV·SMV-IVC shut without gastrointestinal varices, embolization therapy using steel coils and done by the intravenous approach is easy and noninvasive. On the other hand, in cases of complex PV-SMV-IVC shunt with gastrointestinal varices, dual balloon occluded embolization therapy using a liquid sclerosing agent and done by the intravenous and portal approaches is preferable. (author)

  13. Percutaneous transluminal angioplasty of an occluded surgical splenorenal shunt in a 4-year-old child after liver transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Yussim, Ethan; Belenky, Alexander; Atar, Eli [Department of Diagnostic Radiology, Rabin Medical Center, Vascular and Interventional Radiology Unit, Petah Tikva (Israel); Shapiro, Rivka [Schneider Children' s Medical Center, Institute of Pediatric Gastroenterology and Nutrition, Petah Tikva (Israel); Mor, Eytan [Rabin Medical Center, Department of Organ Transplantation, Petah Tikva (Israel)

    2005-07-01

    Percutaneous transluminal angioplasty is increasingly used in children. We present a case of successful balloon angioplasty of an occluded surgical splenorenal shunt in a 4-year-old child who underwent liver transplantation because of biliary atresia. Percutaneous reopening of the shunt is a relatively safe procedure that may spare patients of surgical intervention. (orig.)

  14. Percutaneous transluminal angioplasty of an occluded surgical splenorenal shunt in a 4-year-old child after liver transplantation

    International Nuclear Information System (INIS)

    Yussim, Ethan; Belenky, Alexander; Atar, Eli; Shapiro, Rivka; Mor, Eytan

    2005-01-01

    Percutaneous transluminal angioplasty is increasingly used in children. We present a case of successful balloon angioplasty of an occluded surgical splenorenal shunt in a 4-year-old child who underwent liver transplantation because of biliary atresia. Percutaneous reopening of the shunt is a relatively safe procedure that may spare patients of surgical intervention. (orig.)

  15. Use of transsplenic injection of agitated saline and heparinized blood for the ultrasonographic diagnosis of macroscopic portosystemic shunts in dogs.

    Science.gov (United States)

    Gómez-Ochoa, Pablo; Llabrés-Díaz, Francisco; Ruiz, Sergio; Corda, Andrea; Prieto, Saul; Sosa, Ivan; Gregori, Tommaso; Gascón, Manuel; Couto, Guillermo C

    2011-01-01

    We describe the use of ultrasonography-guided percutaneous splenic injection of agitated saline and heparinized blood for the diagnosis of portosystemic shunts (PSS) in 34 dogs. Agitated saline mixed with 1 ml of heparinized autologous blood was injected into the spleen of 34 sedated dogs under sonographic guidance. The transducer was then sequentially repositioned to visualize the portal vein, the caudal vena cava, and the right atrium through different acoustic windows. It was possible to differentiate between intrahepatic and extrahepatic shunts depending on the entry point of the microbubbles into the caudal vena cava. Portoazygos shunts and portocaval shunts could be differentiated based on the presence of microbubbles in the caudal vena cava and/or the right atrium. In one dog, collateral circulation due to portal hypertension was identified. In dogs with a single extrahepatic shunt, the microbubbles helped identify the shunting vessel. The technique was also used postoperatively to assess the efficacy of shunt closure. All abnormal vessels were confirmed by exploratory laparotomy or with ultrasonographic identification of the shunting vessel. Ultrasound-guided transsplenic injection of agitated saline with heparinized blood should be considered as a valuable technique for the diagnosis of PSS; it is easy to perform, safe, and the results are easily reproducible.

  16. Hepatic gene expression and plasma albumin concentration related to outcome after attenuation of a congenital portosystemic shunt in dogs

    NARCIS (Netherlands)

    Kummeling, A.; Penning, L.C.; Rothuizen, J.; Brinkhof, B.; Weber, M.F.; van Sluijs, F.J.

    2012-01-01

    Abstract In dogs with a congenital portosystemic shunt (CPSS), the outcome after CPSS attenuation is difficult to predict but is most likely related to hepatic and vascular proliferation that follows the attenuation. The aim of this study was to evaluate the prognostic value of shunt localization

  17. Anatomical Closure of Left-to-Right Shunts in Premature Infants with Bronchopulmonary Dysplasia and Pulmonary Hypertension: A Cautionary Tale

    Directory of Open Access Journals (Sweden)

    Narendra R. Dereddy

    2015-10-01

    Full Text Available Closure of a systemic to pulmonary shunt in premature infants with bronchopulmonary dysplasia may be beneficial, but in the presence of pulmonary hypertension is controversial. Here, we discuss two premature infants with pulmonary hypertension who developed acute pulmonary hypertensive crisis after closure of these shunts and hence advise caution.

  18. Shunt Surgery, Right Heart Catheterization, and Vascular Morphometry in a Rat Model for Flow-induced Pulmonary Arterial Hypertension

    NARCIS (Netherlands)

    van der Feen, Diederik E.; Weij, Michel; Smit-van Oosten, Annemieke; Jorna, Lysanne M.; Hagdorn, Quint A. J.; Bartelds, Beatrijs; Berger, Rolf M. F.

    2017-01-01

    In this protocol, PAH is induced by combining a 60 mg/kg monocrotalin (MCT) injection with increased pulmonary blood flow through an aorto-caval shunt (MCT+Flow). The shunt is created by inserting an 18-G needle from the abdominal aorta into the adjacent caval vein. Increased pulmonary flow has been

  19. Quality measurement in the shunt treatment of hydrocephalus: analysis and risk adjustment of the Revision Quotient.

    Science.gov (United States)

    Piatt, Joseph H; Freibott, Christina E

    2014-07-01

    OBJECT.: The Revision Quotient (RQ) has been defined as the ratio of the number of CSF shunt revisions to the number of new shunt insertions for a particular neurosurgical practice in a unit of time. The RQ has been proposed as a quality measure in the treatment of childhood hydrocephalus. The authors examined the construct validity of the RQ and explored the feasibility of risk stratification under this metric. The Kids' Inpatient Database for 1997, 2000, 2003, 2006, and 2009 was queried for admissions with diagnostic codes for hydrocephalus and procedural codes for CSF shunt insertion or revision. Revision quotients were calculated for hospitals that performed 12 or more shunt insertions annually. The univariate associations of hospital RQs with a variety of institutional descriptors were analyzed, and a generalized linear model of the RQ was constructed. There were 12,244 admissions (34%) during which new shunts were inserted, and there were 23,349 admissions (66%) for shunt revision. Three hundred thirty-four annual RQs were calculated for 152 different hospitals. Analysis of variance in hospital RQs over the 5 years of study data supports the construct validity of the metric. The following factors were incorporated into a generalized linear model that accounted for 41% of the variance of the measured RQs: degree of pediatric specialization, proportion of initial case mix in the infant age group, and proportion with neoplastic hydrocephalus. The RQ has construct validity. Risk adjustment is feasible, but the risk factors that were identified relate predominantly to patterns of patient flow through the health care system. Possible advantages of an alternative metric, the Surgical Activity Ratio, are discussed.

  20. Barry shunt for treatment of a 76-hour stuttering priapism without subsequent erectile dysfunction

    Directory of Open Access Journals (Sweden)

    Osmonov DK

    2014-07-01

    Full Text Available Daniar Kurmanbekovich Osmonov, Aleksey Aksenov, Andrea Nathaly Guerra Sandoval, Almut Kalz, Klaus Peter Juenemann Department of Urology and Pediatric Urology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany Introduction: This paper reports treatment of a 76-hour low-flow priapism with a shunting procedure that was first described by Barry in 1976. We were able to observe the preservation of erectile function despite the long period of ischemia. A review of the literature shows that there are few reports of erectile function recovery after a priapism of similar duration. Materials and methods: A 42-year-old patient presented with a 76-hour priapism, probably caused by consumption of alcohol and illegal drugs. A Barry Shunt procedure was performed. The erectile function of the patient was assessed by means of International Index of Erectile Function score over a follow-up period of 30 months. Moreover, we reviewed different surgical options for treatment of priapism in the literature. Results: Partial return of erection without sexual arousal occurred on two occasions during the 10-day hospitalization, but was treated by manipulation of the penis, ie, by milking the tumescence into the shunt. After 3 months, the shunt was still palpable as a subcutaneous swelling. Six months postoperatively, the residual swelling had disappeared. The International Index of Erectile Function score was of 21 without phosphodiesterase type 5 inhibitors after a follow-up of 2.5 years. Conclusion: Barry shunt is an effective alternative surgical option for the treatment of low-flow priapism. In the case of our patient, it was also effective after a 76-hour-lasting priapism. Keywords: low flow priapism, erectile function, cavernovenous shunt, surgical treatment of stuttering priapism

  1. Experimental study of an endothelial progenitor cell coated stent in transjugular intrahepatic portosystemic shunt

    International Nuclear Information System (INIS)

    Shi Hongjian; Teng Gaojun; Cao Aihong; Chen Jun; Deng Gang

    2009-01-01

    Objective: To evaluate the efficacy of a self-expandable metal stent coated with autologous endothelial progenitor cells (EPCs) for prevention of restenosis in transjugular intrahepatic portosystemic shunt (TIPS) in a swine model. Methods: EPCs were coated on the metal stents using fibrin gel before TIPS procedure. TIPS was performed in 15 young adult pigs, using an autologous EPC-seeded stent (treatment group, n=9) or a conventional bare metal stent (control group, n=6). All pigs were sacrificed at 2 weeks after TIPS procedure. Portography was performed immediately before the euthanasia. Gross and microscopic pathological exams and immunohistochemical exams of the TIPS track specimens were performed. Fisher test and t test were used to analyse the data. Results: TIPS was performed successfully in all the 15 swine. On day 14 of follow-up, direct portography and necropsy demonstrated that 5 shunts remained patent, 2 shunts stenosed, and the remaining 2 shunts occluded in the treatment group (n=9); while 5 shunts were occluded and one shunt was stenotic in the control group (n=6). The patency rate was 56% vs 0 (P=0.03) between the two groups. Histological analyses showed a greater pseudo-intimal hyperplasia in the TIPS track of the control group than that of the treatment group (pseudointimal thickness at hepatic vein, hepatic parenchyma and portal vein site was (1.2±0.4), (1.3±0.5), (1.5±0.4) mm vs (1.0±0.6), (0.9±0.5), (1.0±0.4) mm respectively (P<0.05). Conclusion: The EPC-coated metal stent is feasibly constructed in vitro and improves the patency in TIPS in a porcine model. (authors)

  2. Delayed Catheter-Related Intracranial Hemorrhage After a Ventriculoperitoneal or Ventriculoatrial Shunt in Hydrocephalus.

    Science.gov (United States)

    Qian, Zhouqi; Gao, Liang; Wang, Ke; Pandey, Sajan

    2017-11-01

    Delayed catheter-related intracranial hemorrhage is not rare after a ventriculoperitoneal (VP) or ventriculoatrial (VA) shunt for the treatment of hydrocephalus. Immediate postoperative catheter-related intracranial hemorrhage is possibly due to the procedure itself; however, delayed intracranial hemorrhage may have other underlying mechanisms. This study aimed to investigate the clinical characteristics and reveal the risk factors of delayed catheter-related intracranial hemorrhage after a VP or VA shunt. We did a retrospective study to review patients with hydrocephalus and underwent VP or VA shunt in our department from September 2011 to December 2015. We reviewed the clinical characteristics of the patients with delayed catheter-related intracranial hemorrhage, and its risk factors were analyzed with SPSS 16.0. Of the 218 patients enrolled in the study (145 male, 73 female), 17 (7.8%) patients experienced delayed catheter-related intracranial hemorrhage, including 11 of 151 (7.3%) patients with a VP shunt and 6 of 67 (9.0%) patients with a VA shunt. Additionally, 4 of the 16 patients with postoperative low-molecular-weight heparin (LMWH) therapy and 13 of the 202 patients without LMWH experienced bleeding, showing a significant difference (25% vs. 6.4%, P = 0.026). The relative risk was 4.8 (95% confidence interval: 1.4-17.1). Delayed catheter-related intracranial hemorrhage is not rare after a VP or VA shunt. However, most patients can be cured after appropriate treatment. Postoperative anticoagulation therapy with enoxaparin may be associated with an increased risk of bleeding. Copyright © 2017. Published by Elsevier Inc.

  3. Initial shunt type at the Norwood operation impacts myocardial function in hypoplastic left heart syndrome.

    Science.gov (United States)

    Ruotsalainen, Hanna K; Pihkala, Jaana; Salminen, Jukka; Hornberger, Lisa K; Sairanen, Heikki; Ojala, Tiina

    2017-08-01

    We investigated the impact of initial shunt type, a Blalock-Taussig (BT) shunt versus a right ventricle to pulmonary artery conduit (RV-PA) on myocardial function at different stages of surgical palliation in patients with hypoplastic left heart syndrome (HLHS). A population-based cohort of 63 Finnish children with HLHS (BT n  = 23, RV-PA n  = 40) born between 2003 and 2010 were studied retrospectively by echocardiography prior to Stages 1, 2 and 3 palliation and 0.5-3 years after Stage 3. For comparison of systolic myocardial function, we evaluated the RV fractional area change (FAC), strain, strain rate and mechanical synchrony from the apical 4-chamber view by velocity vector imaging. There were no intergroup differences in demographics during the study period. At baseline, no intergroup differences were detected in RV systolic myocardial function. Before Stage 2, RV FAC was higher ( P  = 0.03) in the RV-PA conduit group. At Stage 3, an increase in all systolic myocardial functional parameters was observed in the BT shunt group. After Stage 3, the BT shunt group had better RV systolic function. In multiple regression analysis, the shunt type and the stage of palliation had an impact on myocardial function. Although patients with HLHS initially palliated with a BT shunt demonstrate lower RV FAC after Stage I, RV FAC improves after Stage 2 with better systolic performance after Stage 3 compared with those initially palliated with an RV-PA conduit. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  4. Percutaneous Mesocaval Shunt Creation in a Patient with Chronic Portal and Superior Mesenteric Vein Thrombosis

    International Nuclear Information System (INIS)

    Bercu, Zachary L.; Sheth, Sachin B.; Noor, Amir; Lookstein, Robert A.; Fischman, Aaron M.; Nowakowski, F. Scott; Kim, Edward; Patel, Rahul S.

    2015-01-01

    The creation of a transjugular intrahepatic portosystemic shunt (TIPS) is a critical procedure for the treatment of recurrent variceal bleeding and refractory ascites in the setting of portal hypertension. Chronic portal vein thrombosis remains a relative contraindication to conventional TIPS and options are limited in this scenario. Presented is a novel technique for management of refractory ascites in a patient with hepatitis C cirrhosis and chronic portal and superior mesenteric vein thrombosis secondary to schistosomiasis and lupus anticoagulant utilizing fluoroscopically guided percutaneous mesocaval shunt creation

  5. Cerebrospinal Fluid Lumbar Tapping Utilization for Suspected Ventriculoperitoneal Shunt Under-Drainage Malfunctions.

    Science.gov (United States)

    Lee, Jong-Beom; Ahn, Ho-Young; Lee, Hong-Jae; Yang, Ji-Ho; Yi, Jin-Seok; Lee, Il-Woo

    2017-01-01

    The diagnosis of shunt malfunction can be challenging since neuroimaging results are not always correlated with clinical outcomes. The purpose of this study was to evaluate the efficacy of a simple, minimally invasive cerebrospinal fluid (CSF) lumbar tapping test that predicts shunt under-drainage in hydrocephalus patients. We retrospectively reviewed the clinical and radiological features of 48 patients who underwent routine CSF lumbar tapping after ventriculoperitoneal shunt (VPS) operation using a programmable shunting device. We compared shunt valve opening pressure and CSF lumbar tapping pressure to check under-drainage. The mean pressure difference between valve opening pressure and CSF lumbar tapping pressure of all patients were 2.21±24.57 mmH 2 O. The frequency of CSF lumbar tapping was 2.06±1.26 times. Eighty five times lumbar tapping of 41 patients showed that their VPS function was normal which was consistent with clinical improvement and decreased ventricle size on computed tomography scan. The mean pressure difference in these patients was -3.69±19.20 mmH 2 O. The mean frequency of CSF lumbar tapping was 2.07±1.25 times. Fourteen cases of 10 patients revealed suspected VPS malfunction which were consistent with radiological results and clinical symptoms, defined as changes in ventricle size and no clinical improvement. The mean pressure difference was 38.07±23.58 mmH 2 O. The mean frequency of CSF lumbar tapping was 1.44±1.01 times. Pressure difference greater than 35 mmH 2 O was shown in 2.35% of the normal VPS function group (2 of 85) whereas it was shown in 64.29% of the suspected VPS malfunction group (9 of 14). The difference was statistically significant ( p =0.000001). Among 10 patients with under-drainage, 5 patients underwent shunt revision. The causes of the shunt malfunction included 3 cases of proximal occlusion and 2 cases of distal obstruction and valve malfunction. Under-drainage of CSF should be suspected if CSF lumbar tapping

  6. Pancreaticoportal Fistula and Disseminated Fat Necrosis After Revision of a Transjugular Intrahepatic Portosystemic Shunt

    International Nuclear Information System (INIS)

    Klein, Seth J.; Saad, Nael; Korenblat, Kevin; Darcy, Michael D.

    2013-01-01

    A 59-year old man with alcohol related cirrhosis and portal hypertension was referred for transjugular intrahepatic portosystemic shunt (TIPS) to treat his refractory ascites. Ten years later, two sequential TIPS revisions were performed for shunt stenosis and recurrent ascites. After these revisions, he returned with increased serum pancreatic enzyme levels and disseminated superficial fat necrosis; an iatrogenic pancreaticoportal vein fistula caused by disruption of the pancreatic duct was suspected. The bare area of the TIPS was subsequently lined with a covered stent-graft, and serum enzyme levels returned to baseline. In the interval follow-up period, the patient has clinically improved.

  7. Finite Element and Experimental Study of Shunting in Resistance Spot Welding

    DEFF Research Database (Denmark)

    Seyyedian Choobi, M.; Nielsen, C. V.; Bay, N.

    2015-01-01

    This research is focused on one of the problems frequently encountered in spot welding in industry. In many applications several spot welds are made close to each other. The spots made after the first spot may become smaller in size due to shunt effect. A numerical and experimental study has been...... conducted to investigate the effect of shunting on nugget size in spot welding of HSLA steel sheets. Different cases with different spacing between weld spots have been examined. The nugget sizes have been measured by metallographic examination and have been compared with 3D finite element simulations...

  8. Pancreaticoportal Fistula and Disseminated Fat Necrosis After Revision of a Transjugular Intrahepatic Portosystemic Shunt

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Seth J., E-mail: kleins@mir.wustl.edu; Saad, Nael [Washington University School of Medicine, Interventional Radiology Section, Mallinckrodt Institute of Radiology (United States); Korenblat, Kevin [Washington University School of Medicine, Division of Gastroenterology, Department of Internal Medicine (United States); Darcy, Michael D. [Washington University School of Medicine, Interventional Radiology Section, Mallinckrodt Institute of Radiology (United States)

    2013-04-15

    A 59-year old man with alcohol related cirrhosis and portal hypertension was referred for transjugular intrahepatic portosystemic shunt (TIPS) to treat his refractory ascites. Ten years later, two sequential TIPS revisions were performed for shunt stenosis and recurrent ascites. After these revisions, he returned with increased serum pancreatic enzyme levels and disseminated superficial fat necrosis; an iatrogenic pancreaticoportal vein fistula caused by disruption of the pancreatic duct was suspected. The bare area of the TIPS was subsequently lined with a covered stent-graft, and serum enzyme levels returned to baseline. In the interval follow-up period, the patient has clinically improved.

  9. Percutaneous Mesocaval Shunt Creation in a Patient with Chronic Portal and Superior Mesenteric Vein Thrombosis

    Energy Technology Data Exchange (ETDEWEB)

    Bercu, Zachary L., E-mail: zachary.bercu@mountsinai.org; Sheth, Sachin B., E-mail: sachinsheth@gmail.com [Icahn School of Medicine at Mount Sinai, Division of Interventional Radiology (United States); Noor, Amir, E-mail: amir.noor@gmail.com [The George Washington University School of Medicine and Health Sciences (United States); Lookstein, Robert A., E-mail: robert.lookstein@mountsinai.org; Fischman, Aaron M., E-mail: aaron.fischman@mountsinai.org; Nowakowski, F. Scott, E-mail: scott.nowakowski@mountsinai.org; Kim, Edward, E-mail: edward.kim@mountsinai.org; Patel, Rahul S., E-mail: rahul.patel@mountsinai.org [Icahn School of Medicine at Mount Sinai, Division of Interventional Radiology (United States)

    2015-10-15

    The creation of a transjugular intrahepatic portosystemic shunt (TIPS) is a critical procedure for the treatment of recurrent variceal bleeding and refractory ascites in the setting of portal hypertension. Chronic portal vein thrombosis remains a relative contraindication to conventional TIPS and options are limited in this scenario. Presented is a novel technique for management of refractory ascites in a patient with hepatitis C cirrhosis and chronic portal and superior mesenteric vein thrombosis secondary to schistosomiasis and lupus anticoagulant utilizing fluoroscopically guided percutaneous mesocaval shunt creation.

  10. Correlation of dynamic parameter modification and ASET sensitivity in a shunt voltage reference

    International Nuclear Information System (INIS)

    Roche, N.J.H.; Buchner, S.P.; Warner, J.H.; McMorrow, D.; Dusseau, L.; Boch, J.; Saigne, F.; Kruckmeyer, K.; Auriel, G.; Azais, B.

    2012-01-01

    Analog Single Event Transients (ASETs) in two different shunt voltage references used in power management systems are investigated. Little has been published regarding how the dynamic parameter changes induced by external circuit design, such as time constant, damping coefficient or natural frequency affect ASET shapes. Modifications of the dynamic parameters of the circuit are measured by step response measurement. A correlation between dynamic parameters and ASET laser testing results is proposed. This study establishes the correlation between the dynamic parameters of a shunt voltage reference and ASET parameters such as pulse duration, and positive and negative amplitude. (authors)

  11. Controlling chaos in RCL-shunted Josephson junction by delayed linear feedback

    International Nuclear Information System (INIS)

    Feng Yuling; Shen Ke

    2008-01-01

    The resistively-capacitively-inductively-shunted (RCL-shunted) Josephson junction (RCLSJJ) shows chaotic behaviour under some parameter conditions. Here a scheme for controlling chaos in the RCLSJJ is presented based on the linear feedback theory. Numerical simulations show that this scheme can be effectively used to control chaotic states in this junction into stable periodic states. Moreover, the different stable period states with different period numbers can be obtained by appropriately adjusting the feedback intensity and delay time without any pre-knowledge of this system required

  12. Progressive Functional Underdrainage in Cerebrospinal Fluid Shunt-Dependent Women During Pregnancy: Case Report and Review of the Literature.

    Science.gov (United States)

    Krauss, Philipp; Fritz-Naville, Marco; Regli, Luca; Stieglitz, Lennart Henning

    2018-01-01

    Since the 1950s cerebrospinal fluid (CSF) shunt dependency has no longer been a contradiction to normal life, including sexuality and pregnancy in women, because of advances in the understanding of hydrocephalus and shunt technology. Although pregnancy in shunt-dependent women is rare, it causes uncertainty among treating physicians. We report the case of a 34-year-old pregnant woman with a ventriculoperitoneal shunt. Throughout her pregnancy she experienced progressive symptoms of CSF underdrainage without any signs of other pregnancy-related complications. After the delivery of a healthy infant, shunt resistance had to be readjusted to prepregnancy levels. A comprehensive review of the literature reports in English, listed in PubMed, is provided. Conservative treatment of pregnancy-related functional underdrainage by consecutive valve pressure adjustment is possible, easy, and safe. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Reversibility of hyperintense globus pallidus on T 1-weighted MRI following surgery for a portosystemic shunt in an 8-year-old girl

    International Nuclear Information System (INIS)

    Ikeda, Shinji; Sera, Yoshihisa; Yoshida, Mituhiro; Ohshiro, Hajime; Uchino, Shinichiro; Seguchi, Sasa; Endo, Fumio

    1999-01-01

    An 8-year-old Japanese girl with a portosystemic shunt had shown hyperammonaemia since she was 3 years of age. MRI of her brain showed bilateral hyperintense globus pallidus. A portosystemic shunt was evident on US and angiography. She underwent surgical banding of the shunt, after which the lesion and clinical symptoms disappeared. (orig.)

  14. Bilateral Coordination Strategy of Supply Chain with Bidirectional Option Contracts under Inflation

    Directory of Open Access Journals (Sweden)

    Nana Wan

    2015-01-01

    Full Text Available As far as the price increase and the demand contraction caused by inflation are concerned, we establish a Stackelberg game model that incorporates bidirectional option contracts and the effect of inflation and derive the optimal ordering and production policies on a one-period two-stage supply chain composed of one supplier and one retailer. Through using the model of wholesale price contracts as the benchmark, we find that the introduction of bidirectional option contracts can benefit both the supplier and the retailer under inflation scenarios. Based on the conclusions drawn above, we design the bilateral coordination mechanism from the different perspective of two members involved and discuss how bidirectional option contracts should be set to achieve channel coordination under inflation scenarios. Through the sensitivity analysis, we illustrate the effect of inflation on the optimal decision variables and the optimal expected profits of the two parties with bidirectional option contracts.

  15. Integrable hydrodynamics of Calogero-Sutherland model: bidirectional Benjamin-Ono equation

    International Nuclear Information System (INIS)

    Abanov, Alexander G; Bettelheim, Eldad; Wiegmann, Paul

    2009-01-01

    We develop a hydrodynamic description of the classical Calogero-Sutherland liquid: a Calogero-Sutherland model with an infinite number of particles and a non-vanishing density of particles. The hydrodynamic equations, being written for the density and velocity fields of the liquid, are shown to be a bidirectional analog of the Benjamin-Ono equation. The latter is known to describe internal waves of deep stratified fluids. We show that the bidirectional Benjamin-Ono equation appears as a real reduction of the modified KP hierarchy. We derive the chiral nonlinear equation which appears as a chiral reduction of the bidirectional equation. The conventional Benjamin-Ono equation is a degeneration of the chiral nonlinear equation at large density. We construct multi-phase solutions of the bidirectional Benjamin-Ono equations and of the chiral nonlinear equations

  16. Radiation Exposure in Transjugular Intrahepatic Portosystemic Shunt Creation

    Energy Technology Data Exchange (ETDEWEB)

    Miraglia, Roberto, E-mail: rmiraglia@ismett.edu; Maruzzelli, Luigi, E-mail: lmaruzzelli@ismett.edu; Cortis, Kelvin, E-mail: kelvincortis@ismett.edu [Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Radiology Service, Department of Diagnostic and Therapeutic Services (Italy); D’Amico, Mario, E-mail: mdamico@ismett.edu [University of Palermo, Department of Radiology (Italy); Floridia, Gaetano, E-mail: gfloridia@ismett.edu; Gallo, Giuseppe, E-mail: ggallo@ismett.edu; Tafaro, Corrado, E-mail: ctafaro@ismett.edu; Luca, Angelo, E-mail: aluca@ismett.edu [Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Radiology Service, Department of Diagnostic and Therapeutic Services (Italy)

    2016-02-15

    PurposeTransjugular intrahepatic portosystemic shunt (TIPS) creation is considered as being one of the most complex procedures in abdominal interventional radiology. Our aim was twofold: quantification of TIPS-related patient radiation exposure in our center and identification of factors leading to reduced radiation exposure.Materials and methodsThree hundred and forty seven consecutive patients underwent TIPS in our center between 2007 and 2014. Three main procedure categories were identified: Group I (n = 88)—fluoroscopic-guided portal vein targeting, procedure done in an image intensifier-based angiographic system (IIDS); Group II (n = 48)—ultrasound-guided portal vein puncture, procedure done in an IIDS; and Group III (n = 211)—ultrasound-guided portal vein puncture, procedure done in a flat panel detector-based system (FPDS). Radiation exposure (dose-area product [DAP], in Gy cm{sup 2} and fluoroscopy time [FT] in minutes) was retrospectively analyzed.ResultsDAP was significantly higher in Group I (mean ± SD 360 ± 298; median 287; 75th percentile 389 Gy cm{sup 2}) as compared to Group II (217 ± 130; 178; 276 Gy cm{sup 2}; p = 0.002) and Group III (129 ± 117; 70; 150 Gy cm{sup 2}p < 0.001). The difference in DAP between Groups II and III was also significant (p < 0.001). Group I had significantly longer FT (25.78 ± 13.52 min) as compared to Group II (20.45 ± 10.87 min; p = 0.02) and Group III (19.76 ± 13.34; p < 0.001). FT was not significantly different between Groups II and III (p = 0.73).ConclusionsReal-time ultrasound-guided targeting of the portal venous system during TIPS creation results in a significantly lower radiation exposure and reduced FT. Further reduction in radiation exposure can be achieved through the use of modern angiographic units with FPDS.

  17. 10 Gb/s bidirectional single fibre long reach PON link with distributed Raman amplification

    DEFF Research Database (Denmark)

    Tafur Monroy, Idelfonso; Kjær, Rasmus; Jeppesen, Palle

    2006-01-01

    We report operation of a single fibre bidirectional 80 km long reach PON link with symmetric up- and-downstream data rate of 10 Gb/s supported by distributed Raman fibre amplification only.......We report operation of a single fibre bidirectional 80 km long reach PON link with symmetric up- and-downstream data rate of 10 Gb/s supported by distributed Raman fibre amplification only....

  18. Bidirectional effects between parenting and aggressive child behavior in the context of a preventive intervention

    OpenAIRE

    Brinke, L.W. te; Dekovic, M.; Stoltz, S.E.M.J.; Cillessen, A.H.N.

    2017-01-01

    Over time, developmental theories and empirical studies have gradually started to adopt a bidirectional viewpoint. The area of intervention research is, however, lagging behind in this respect. This longitudinal study examined whether bidirectional associations between (changes in) parenting and (changes in) aggressive child behavior over time differed in three conditions: a child intervention condition, a child + parent intervention condition and a control condition. Participants were 267 ch...

  19. A New Bi-Directional Projection Model Based on Pythagorean Uncertain Linguistic Variable

    OpenAIRE

    Huidong Wang; Shifan He; Xiaohong Pan

    2018-01-01

    To solve the multi-attribute decision making (MADM) problems with Pythagorean uncertain linguistic variable, an extended bi-directional projection method is proposed. First, we utilize the linguistic scale function to convert uncertain linguistic variable and provide a new projection model, subsequently. Then, to depict the bi-directional projection method, the formative vectors of alternatives and ideal alternatives are defined. Furthermore, a comparative analysis with projection model is co...

  20. Bidirectional soliton spectral tunneling effects in the regime of optical event horizon

    DEFF Research Database (Denmark)

    Gu, Jie; Guo, Hairun; Wang, Shaofei

    2015-01-01

    We study the cross-phase-modulation-induced soliton spectral shifting in the regime of the optical event horizon. The perturbed soliton to either red-shifting or blue-shifting is controllable, which could evoke bidirectional soliton spectral tunneling effects.......We study the cross-phase-modulation-induced soliton spectral shifting in the regime of the optical event horizon. The perturbed soliton to either red-shifting or blue-shifting is controllable, which could evoke bidirectional soliton spectral tunneling effects....