Sensitivity-analysis method for inverse simulation application

An important criticism of traditional methods of inverse simulation that are based on the Newton–Raphson algorithm is that they suffer from numerical problems. In this paper these problems are discussed and a new method based on sensitivity-analysis theory is developed and evaluated. The Jacobian matrix may be calculated by solving a sensitivity equation and this has advantages over the approximation methods that are usually applied when the derivatives of output variables with respect to inputs cannot be found analytically. The methodology also overcomes problems of input-output redundancy that arise in the traditional approaches to inverse simulation. The sensitivity- analysis approach makes full use of information within the time interval over which key quantities are compared, such as the difference between calculated values and the given ideal maneuver after each integration step. Applications to nonlinear HS125 aircraft and Lynx helicopter models show that, for this sensitivity-analysis method, more stable and accurate results are obtained than from use of the traditional Newton–Raphson approach

Dural Arteriovenous Malformations: A Review of the Literature and a Presentation of the JHN Series

Dural arteriovenous malformations (DAVMs), also known as dural arteriovenous fistulas, are arteriovenous shunts from a dural arterial supply to a dural venous channel, typically supplied by pachymeningeal arteries and located near a major venous sinus.1 The etiology of these lesions is not fully understood. DAVMs in the pediatric population are associated with structural venous abnormalities ,2 but the majority of DAVMs are thought to be acquired. Different etiologies have been implicated in this phenomenon, namely: sinus thrombosis, trauma or surgery.2–

Endovascular Treatment of Cerebral Mycotic Aneurysm: A Review of the Literature and Single Center Experience

The management of mycotic aneurysm has always been subject to controversy. The aim of this paper is to review the literature on the intracranial infected aneurysm from pathogenesis till management while focusing mainly on the endovascular interventions. This novel solution seems to provide additional benefits and long-term favorable outcomes

Redefining Onyx HD 500 in the Flow Diversion Era

We report the largest US case series results using Onyx HD-500 (EV3), a new liquid embolic agent, in the successful treatment of 21 patients with wide-neck intracranial aneurysms (mean size 4.5 mm), which are at increased risk of incomplete occlusion or recanalization with standard endovascular intervention utilizing detachable platinum coils. All aneurysms were located in the anterior circulation, and three aneurysms presented as acute subarachnoid hemorrhages. Complete aneurysm occlusion was present in 19 of 21 patients (90%). On six-month followup, one patient with an initially small residual neck progressed to total occlusion. Aneurysm recanalization was not detected in any patients on mean follow up of 8.9 months in 11 patients. Four patients experienced transient neurologic deficits in the immediate postoperative period and one in a delayed fashion. Embolization with the liquid embolic agent Onyx appears to be a safe and effective endovascular modality of treatment for wide-neck aneurysms or recurrent aneurysms that had previously failed treatment with detachable coils