432 research outputs found
Canonical D = 1 supergravity framework for FLRW cosmology
We construct an extension of standard flat FLRW cosmology with matter,
possessing local D = 1, N = 1 proper-time supersymmetry. The fundamental
equation for the resulting mini-superspace models of quantum universes is a
Dirac-like analogue of the Friedmann and Wheeler-DeWitt equations. We provide
solutions of this equation for specific matter configurations based on the
supersymmetric O(3) and O(2, 1) sigma-models. It turns out that in the compact
model the volume rate of growth of the universe is quantized and non-vanishing
due to the zero-point energy of the scalar fields. In the non-compact model the
spectrum of the growth rates is continuous but subject to an uncertainty
relation involving the scale and the growth factor.Comment: 14 pages, no figure
Bedrijfsplannen voor een 24 ha bedrijf op zandgrond : gebaseerd op de mogelijkheden van het stikstofproefbedrijf van A. de Kock te Bergen op Zoom
Heparin as a risk factor for perigraft seroma complicating the modified Blalock-Taussig shunt
OBJECTIVE: The purpose of this study was to determine the risk factors associated with the occurrence of perigraft seromas complicating systemic-to-pulmonary polytetrafluoroethylene grafts. METHODS: Clinical and perioperative variables were reexamined, blinded for the outcome variable perigraft seroma, in 60 patients undergoing 67 consecutive graft procedures in a 3.5-year period. RESULTS: Eight cases of perigraft seroma were diagnosed in six patients. Univariate analysis revealed age (p = 0.02), a diagnosis of pulmonary atresia with ventricular septal defect and systemic-pulmonary collaterals (p = 0.001), reimplantation of collaterals during the procedure (p < 0.001), and intravenous heparin administered after operation (p < 0.0001) as risk factors for symptomatic perigraft seroma. Multivariable analysis defined heparin as the only significant factor associated with symptomatic perigraft seroma. Consolidation of the upper lobe on chest radiograph, ipsilateral to the shunt, directly after operation (p = 0.01), but especially 8 to 10 days after operation (p < 0.0001), or the need for prolonged drainage of pleural fluid (p < 0.0001) were correlated with the occurrence of perigraft seroma. Perigraft seroma led to four early rethoracotomies in three patients and to accelerated corrective surgery in three cases. Consolidation and absent perfusion of lung segments persisted in two patients. CONCLUSIONS: Our data suggest that the use of heparin leads to an increased risk of perigraft seroma, complicating systemic-pulmonary polytetrafluoroethylene grafts. Prolonged pleural drainage and/or postoperative consolidation of the upper lobe indicate the development of symptomatic perigraft seroma. Treatment is controversial and results are unpredictable. Expectative management seems to be justified so long as permitted by the clinical condition
PKS 1018-42: A Powerful Kinetically Dominated Quasar
We have identified PKS 1018-42 as a radio galaxy with extraordinarily
powerful jets, over twice as powerful as any 3CR source of equal or lesser
redshift except for one (3C196). It is perhaps the most intrinsically powerful
extragalactic radio source in the, still poorly explored, Southern Hemisphere.
PKS 1018-42 belongs to the class of FR II objects that are kinetically
dominated, the jet kinetic luminosity, (calculated at 151 MHz), is 3.4 times larger than the
total thermal luminosity (IR to X-ray) of the accretion flow, . It is the fourth most kinetically dominated
quasar that we could verify from existing radio data. From a review of the
literature, we find that kinetically dominated sources such as PKS 1018-42 are
rare, and list the 5 most kinetically dominated sources found from our review.
Our results for PKS 1018-42 are based on new observations from the Australia
Telescope Compact Array.Comment: To appear in ApJ Letter
Cardiologist and cardiac surgeon view on decision-making in prosthetic aortic valve selection: does profession matter?
Cardiolog
Optimized Preoperative Planning of Double Outlet Right Ventricle Patients by 3D Printing and Virtual Reality:A Pilot Study
OBJECTIVES: In complex double outlet right ventricle (DORV) patients, the optimal surgical approach may be difficult to assess based on conventional two-dimensional (2D) ultrasound (US) and computed tomography (CT) imaging. The aim of this study is to assess the added value of 3D printed and 3D Virtual Reality (VR) models of the heart used for surgical planning in DORV patients, supplementary to the gold standard 2D imaging modalities.METHODS: Five patients with different DORV-subtypes and high-quality CT scans were selected retrospectively. 3D prints and 3D-VR models were created. Twelve congenital cardiac surgeons and paediatric cardiologists, from three different hospitals, were shown 2D-CT first, after which they assessed the 3D print and 3D-VR models in random order. After each imaging method, a questionnaire was filled in on the visibility of essential structures and the surgical plan.RESULTS: Spatial relationships were generally better visualized using 3D methods (3D printing/3D-VR) than in 2D. The feasibility of VSD patch closure could be determined best using 3D-VR reconstructions (3D-VR 92%, 3D print 66%, and US/CT 46%, P < 0.01). The percentage of proposed surgical plans corresponding to the performed surgical approach was 66% for plans based on US/CT, 78% for plans based on 3D printing, and 80% for plans based on 3D-VR visualization.CONCLUSIONS: This study shows that both 3D printing and 3D-VR have additional value for cardiac surgeons and cardiologists over 2D imaging, because of better visualization of spatial relationships. As a result, the proposed surgical plans based on the 3D visualizations matched the actual performed surgery to a greater extent.</p
P04-25. Exposure of HIV-1 pseudovirus to soluble CD4 increases the breadth of neutralization with sera from macaques immunized with recombinant glycoproteins
Validation of Real-time Transthoracic 3D echocardiography in Children with Congenital Heart Disease
Aims: Assessment of feasibility, accuracy and applicability in clinical practice of real-time three-dimensional echocardiography (RT-3DE) in children with congenital heart defects. Methods and results: From September 2004 to June 2005, 100 consecutive children (57 infants, 43 children > 1 year of age), who were scheduled for corrective intracardiac surgery, were enrolled in this study. RT-3DE was performed with Philips Sonos 7500 echo-system and off-line analysis with TomTec Echoview© software. Quantitative and qualitative assessments of the region of interest were performed on the 3D reconstruction, comparing these results with the anatomic findings and measurements performed during intracardiac surgery. Acquisition of RT-3DE datasets was feasible in 92 of the 100 (92%) patients and acquisition time was 6 ± 3 minutes. The overall quantitative analyses showed an excellent correlation (r < 0.90) between RT-3De and surgery. Also the qualitative analyses were accurate compared with surgical findings, in all patients in which RT-3DE was feasible. Conclusion: This study shows that RT-3DE can be used in the clinical practice for the assessment of intracardiac anatomy in children with congenital heart disease. The information derived from the 3D reconstructions can be taken into consideration in the preoperative planning and management regarding interventional or surgical therapy
Tachyarrhythmia in patients with congenital heart disease:inevitable destiny?
Contains fulltext :
171611.pdf (publisher's version ) (Open Access)The prevalence of patients with congenital heart disease (CHD) has increased over the last century. As a result, the number of CHD patients presenting with late, postoperative tachyarrhythmias has increased as well. The aim of this review is to discuss the present knowledge on the mechanisms underlying both atrial and ventricular tachyarrhythmia in patients with CHD and the advantages and disadvantages of the currently available invasive treatment modalities
Long term outcome after surgical ASD-closure at young age:Longitudinal follow-up up to 50 years after surgery
OBJECTIVES: To describe the clinical outcome and quality of life up to 50 years after surgical atrial septal defect (ASD) closure at young age. Primary outcome is defined as MACE (all-cause mortality, cardiac re-interventions, ischemic stroke, endocarditis, heart failure and symptomatic arrhythmia).METHODS: Single-center, longitudinal cohort-study evaluating 135 consecutive patients who underwent ASD-closure before the age of 15 years between 1968 and 1980. Participants were invited for extensive cardiac evaluation and assessment of quality-of-life every 10 years.RESULTS: Eighty patients (86%) of 93 eligible survivors were included in this study (mean age 52 ± 5 years (range 41-63), 40% male). Median follow-up since surgery was 45 years (range 40-51). Cumulative survival after 50 years was 86% and comparable to the normal Dutch population. Cumulative event-free survival after 45 and 50-years was 59% and 46% respectively (re-intervention in 6, symptomatic arrhythmia in 25, and pacemaker implantation in 10 patients). Right ventricular ejection fraction on CMR was diminished in 6%. Exercise capacity was normal in 77%. There was no pulmonary hypertension. NT-proBNP was elevated in 61%. Quality of life was comparable with the general population. No predictors for late events were identified.CONCLUSION: Long-term survival after surgical ASD-closure in childhood is good and not statistically different at 50 years compared to the normal Dutch population. Re-intervention rate is low, there is no pulmonary hypertension. Right ventricular function was diminished in 6%, exercise capacity was good and stable over time with quality of life comparable to the general population. However, supraventricular tachycardia is common.</p
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