Scaling in Numerical Simulations of Domain Walls

We study the evolution of domain wall networks appearing after phase transitions in the early Universe. They exhibit interesting dynamical scaling behaviour which is not yet well understood, and are also simple models for the more phenomenologically acceptable string networks. We have run numerical simulations in two- and three-dimensional lattices of sizes up to 4096^3. The theoretically predicted scaling solution for the wall area density A ~ 1/t is supported by the simulation results, while no evidence of a logarithmic correction reported in previous studies could be found. The energy loss mechanism appears to be direct radiation, rather than the formation and collapse of closed loops or spheres. We discuss the implications for the evolution of string networks.Comment: 7pp RevTeX, 9 eps files (including six 220kB ones

Epilepsy as a dynamic disease of neuronal networks

Epilepsy is a dynamic disease of neuronal networks. To understand how epileptic seizures occur, it is necessary to take into account that the brain of epileptic subjects is able to function in two very distinct modes: a normal state and a state characterized by abnormal oscillations, i.e., epileptic seizures. A main question is how the transition (i.e., a bifurcation) from the normal to the epileptic state can take place. Such transitions do not occur easily in the normal brain due to the set of parameters that maintains the stability of the neuronal networks. In the brain of epileptic subjects, however, these parameters are disturbed so that the threshold for these transitions is much lower and may occur spontaneously. This is the essential difference between the dynamics of a normal and an epileptic brain. Here we consider, first, the main aspects of how the stability of neuronal networks may be maintained and disturbed in epilepsy. Thereafter we discuss how transitions between normal and epileptic behavior may occur in two important systems with respect to epilepsy: networks of the thalamocortical and the hippocampal systems. Finally, the question of how neuronal networks involved in epileptic behavior may be identified in the clinic is analyzed

Neuroimaging Of The Cortical Dysplasias

[No abstract available]626 SUPPL. 3S27S29Barkovich, A.J., Kuzniecky, R., Dobyns, W., A classification scheme for malformations of cortical development (1996) Neuropediatrics, 27, pp. 59-63Palmini, A., Disorders of cortical development (2000) Curr Opin Neurol, 13, pp. 183-192Taylor, D.F.M., Bruton, C., Corsellis, J., Focal dysplasia of the cerebral cortex in epilepsy (1971) J Neurol Neurosurg Psychiatry, 34, pp. 369-387Barkovich, A.J., Chuang, S.H., Unilateral megalencephaly: Correlation of MR imaging and pathologic characteristics (1990) AJNR Am J Neuroradiol, 11, pp. 525-531Kimura, M., Yoshino, K., Maeoka, Y., Hypomelanosis of Ito: MR findings Pediatr Radiol, 24, pp. 68-69Kuzniecky, R., Garcia, J.H., Gaught, E., Cortical dysplasia in temporal lobe epilepsy: Magnetic resonance imaging correlations (1991) Ann Neurol, 29, pp. 293-298Otsubo, H., Hwang, Jay, V., Focal cortical dysplasia in children with localization related epilepsy: EEG, MRI and SPECT findings (1993) Pediatr Neurol, 9, pp. 101-107Martin, N., Debussche, C., DeBroucker, T., Gadolinium-DTPA enhanced MR imaging in tuberous sclerosis (1990) Neuroradiology, 31, pp. 492-497Menor, F., Marti-Bonmati, L., Mulas, F., Neuroimaging in tuberous sclerosis: A clinico-radiological evaluation in pediatric patients (1992) Pediatr Radiol, 22, pp. 485-489Barkovich, A.J., Kjos, B.O., Gray matter heterotopias: MR characteristics and correlation with developmental and neurologic manifestations (1992) Radiology, 182, pp. 493-499Dobyns, W.B., Truwit, C.L., Lissencephaly and other malformations of cortical development: 1995 Update (1995) Neuropediatrics, 26, pp. 132-147Palmini, A., Andermann, F., Aicardi, J., Diffuse cortical dysplasia, or the "double cortes" syndrome: The clinical and epileptic spectrum in 10 patients (1991) Neurology, 41, pp. 1656-1662Van, B.P., David, P., Gillain, C., Perisylvian dysgenesis. Clinical, EEG, MRI and glucose metabolism features in 10 patients (1998) Brain, 121, pp. 2229-2238Barkovich, A.J., Kjos, B.O., Nonlissencephalic cortical dysplasias: Correlation of imaging findings with clinical deficits (1992) AJNR Am J Neuroradiol, 13, pp. 95-103Recommendations for neuroimaging of patients with epilepsy (1997) Epilepsia, 38, pp. 1255-1256Guidelines for neuroimaging evaluation of patients with uncontrolled epilepsy being considered for surgery (1998) Epilepsia, 39, pp. 1375-1376American College of Radiology Appropriateness Criteria for Epilepsy (1996) American College of Radiology Appropriateness Criteria, , Reston, VA: Standards and Accreditation Department, American College of RadiologyBergin, P.S., Fish, D.R., Shorvon, S.D., Magnetic resonance imaging in partial epilepsy: Additional abnormalities shown with the fluid attenuated inversion recovery (FLAIR) pulse sequence (1995) J Neurol Neurosurg Psychiatry, 58, pp. 439-443Jack, C.R., Rydberg, C.H., Krecke, K.N., Mesial temporal sclerosis: Diagnosis with fluid-attenuated inversion-recovery versus spin echo MR imaging (1996) Radiology, 199, pp. 367-373Ashikaga, R., Araki, Y., Ono, Y., Appearance of normal brain maturation on fluid-attenuated inversion-recovery (FLAIR) MR images (1999) AJNR Am J Neuroradiol, 20, pp. 427-431Mugler III, J.P., Brookeman, J.R., Three-dimensional T1-weighted MR imaging with the MPRAGE sequence (1991) J Magn Reson Imaging, 1, p. 561Barkovich, A.J., Rowley, H.A., Andermann, F., MR in partial epilepsy: Value of high resolution volumetric techniques (1995) AJNR Am J Neuroradiol, 16, pp. 339-344Yetkin, F.Z., Mueller, W.M., Morris, G.L., Functional MR activation correlated with intraoperative cortical mapping (1997) AJNR Am J Neuroradiol, 18, pp. 1311-1315Grant, P.E., Barkovich, A.J., Wald, L.L., High-resolution surface-coil MR of cortical lesions in medically refractory epilepsy: A prospective study (1997) AJNR Am J Neuroradiol, 18, pp. 291-301Eriksson, S.H., Symms, M.R., Rugg-Gunn, F.J., Barker, G.J., Duncan, J.S., Diffusion tensor imaging in patients with epilepsy and malformations of cortical development (2001) Brain, 124, pp. 617-626Rugg-Gunn, F.J., Eriksson, S.H., Boulby, P.A., Symms, M.R., Barker, G.J., Duncan, J.S., Magnetization transfer imaging in focal epilepsy (2003) Neurology, 60, pp. 1638-164

Recommendations for the use of structural magnetic resonance imaging in the care of patients with epilepsy: A consensus report from the International League Against Epilepsy Neuroimaging Task Force.

Structural magnetic resonance imaging (MRI) is of fundamental importance to the diagnosis and treatment of epilepsy, particularly when surgery is being considered. Despite previous recommendations and guidelines, practices for the use of MRI are variable worldwide and may not harness the full potential of recent technological advances for the benefit of people with epilepsy. The International League Against Epilepsy Diagnostic Methods Commission has thus charged the 2013-2017 Neuroimaging Task Force to develop a set of recommendations addressing the following questions: (1) Who should have an MRI? (2) What are the minimum requirements for an MRI epilepsy protocol? (3) How should magnetic resonance (MR) images be evaluated? (4) How to optimize lesion detection? These recommendations target clinicians in established epilepsy centers and neurologists in general/district hospitals. They endorse routine structural imaging in new onset generalized and focal epilepsy alike and describe the range of situations when detailed assessment is indicated. The Neuroimaging Task Force identified a set of sequences, with three-dimensional acquisitions at its core, the harmonized neuroimaging of epilepsy structural sequences-HARNESS-MRI protocol. As these sequences are available on most MR scanners, the HARNESS-MRI protocol is generalizable, regardless of the clinical setting and country. The Neuroimaging Task Force also endorses the use of computer-aided image postprocessing methods to provide an objective account of an individual's brain anatomy and pathology. By discussing the breadth and depth of scope of MRI, this report emphasizes the unique role of this noninvasive investigation in the care of people with epilepsy