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Jinwu Jiang - One of the best experts on this subject based on the ideXlab platform.
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parametrization of stillinger Weber potential based on valence force field model application to single layer mos2 and black phosphorus
Nanotechnology, 2015Co-Authors: Jinwu JiangAbstract:We propose parametrizing the Stillinger-Weber potential for covalent materials starting from the valence force-field model. All geometrical parameters in the Stillinger-Weber potential are determined analytically according to the equilibrium condition for each individual potential term, while the energy parameters are derived from the valence force-field model. This parametrization approach transfers the accuracy of the valence force field model to the Stillinger-Weber potential. Furthermore, the resulting Stilliinger-Weber potential supports stable molecular dynamics simulations, as each potential term is at an energy-minimum state separately at the equilibrium configuration. We employ this procedure to parametrize Stillinger-Weber potentials for single-layer MoS2 and black phosphorous. The obtained Stillinger-Weber potentials predict an accurate phonon spectrum and mechanical behaviors. We also provide input scripts of these Stillinger-Weber potentials used by publicly available simulation packages including GULP and LAMMPS.
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parametrization of stillinger Weber potential based on valence force field model application to single layer mos2 and black phosphorus
arXiv: Materials Science, 2015Co-Authors: Jinwu JiangAbstract:We propose to parametrize the Stillinger-Weber potential for covalent materials starting from the valence force field model. All geometrical parameters in the Stillinger-Weber potential are determined analytically according to the equilibrium condition for each individual potential term, while the energy parameters are derived from the valence force field model. This parametrization approach transfers the accuracy of the valence force field model to the Stillinger-Weber potential. Furthermore, the resulting Stilliinger-Weber potential supports for stable molecular dynamics simulations, as each potential term is at energy minimum state separately at the equilibrium configuration. We employ this procedure to parametrize Stillinger-Weber potentials for the single-layer MoS2 and black phosphorous. The obtained Stillinger-Weber potentials predict accurate phonon spectrum and mechanical behaviors. We also provide input scripts of these Stillinger-Weber potentials used by publicly available simulation packages including GULP and LAMMPS.
Timothy G. Murray - One of the best experts on this subject based on the ideXlab platform.
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bilateral diffuse choroidal hemangiomas with unilateral facial nevus flammeus in sturge Weber syndrome
American Journal of Ophthalmology, 2000Co-Authors: Arezo Amirikia, Ingrid U. Scott, Timothy G. MurrayAbstract:PURPOSE: To report bilateral choroidal hemangiomas associated with unilateral facial nevus flammeus in Sturge-Weber syndrome. METHODS: Case report. RESULTS: A 6-year-old male with a left facial nevus flammeus and a history of a left cerebral angioma had been followed 2 years for increasing esotropia. Examination demonstrated bilateral diffuse choroidal hemangiomas with overlying exudative retinal detachments. After bilateral external beam radiotherapy, the retinal detachments resolved and vision improved. CONCLUSION: Patients with Sturge-Weber syndrome and unilateral facial nevus flammeus may harbor bilateral choroidal hemangiomas. Clinical manifestations of the Sturge-Weber syndrome are characteristically unilateral and ipsilateral to the facial nevus flammeus. Bilateral choroidal hemangiomas associated with bilateral facial nevus flammeus are rare. 1,2 We report bilateral diffuse choroidal hemangiomas associated with unilateral facial nevus flammeus in Sturge-Weber syndrome.
Anne M Comi - One of the best experts on this subject based on the ideXlab platform.
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Sturge-Weber Syndrome
Current Treatment Options in Neurology, 2013Co-Authors: Catherine D. Bachur, Anne M ComiAbstract:We try to see the babies prior to the onset of symptoms so that their parents can receive anticipatory guidance regarding seizures and how to recognize and respond to them and so that proper referrals to ophthalmology can be made. If there is any concern on history, exam, or EEG then we obtain a magnetic resonance imaging (MRI) with contrast. If presymptomatic diagnosis of brain involvement is made then treatment with low-dose aspirin is offered and if the brain involvement is extensively bilateral then an anticonvulsant such as levetiracetam is offered as well. Seizures are treated aggressively with a goal of obtaining and maintaining complete seizure suppression as much as possible often with a combination of low-dose aspirin and two anticonvulsants such as levetiracetam and oxcarbazepine. For many patients, this will provide adequate control of their seizures and stroke-like episodes. If the patient fails medical management and seizures are regular and accompanied by plateaued development, significant hemiparesis and visual field deficit and the patient is unilaterally involved and a surgical candidate then surgical management is urged. When the seizures are less regular, little or no hemiparesis or visual field deficit exist, and development is reasonable then this decision is more difficult. For bilaterally involved patients surgery is usually not a good option unless seizures are very severe and mostly coming from one side. Other therapeutic options include the ketogenic/Atkins diet and vagal nerve stimulator although in our experience these usually do not result in cessation of seizures. Endocrine problems occur with increased frequency and must be treated when they are present. The recent discovery of the somatic mutation causing Sturge-Weber syndrome holds promise for new treatment options in the future.
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case report of subdural hematoma in a patient with sturge Weber syndrome and literature review questions and implications for therapy
Journal of Child Neurology, 2013Co-Authors: Jonathan Lopez, Anne M Comi, Kristen W Yeom, Keith Van HarenAbstract:Sturge-Weber syndrome is a neurocutaneous disorder associated with vascular abnormalities in the skin, eye, and brain leading to both acute and chronic cerebral hypoperfusion and, in some affected children, brain injury. Aspirin can reduce stroke-like events and seizure episodes and prevent further brain injuries in these patients. Although a few cases of intracranial hemorrhage in patients with Sturge-Weber syndrome have been reported, prior reports have not discussed this complication with regard to particular therapies. The authors present a toddler with Sturge-Weber syndrome who developed a subdural hematoma in the setting of a mechanical fall with minor head trauma. They discuss the possible role of aspirin in contributing to, or perhaps protecting against, intracranial hemorrhage in patients with Sturge-Weber syndrome. Further data are needed to establish the utility of aspirin in Sturge-Weber syndrome.
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Importance of utilizing a sensitive free thyroxine assay in Sturge-Weber syndrome.
Journal of child neurology, 2012Co-Authors: Laila Siddique, Anne M Comi, Aditya K Sreenivasan, Emily L. Germain-leeAbstract:Sturge-Weber syndrome has been found to result in hypothalamic-pituitary dysfunction including central hypothyroidism. Because central hypothyroidism is more prevalent in Sturge-Weber syndrome than in the general population, we routinely evaluated thyroid function. Here we describe 5 children with Sturge-Weber syndrome on anticonvulsants and diagnosed with hypothyroidism based on thyroid function testing. All 5 patients were eventually tested utilizing the more accurate free thyroxine equilibrium dialysis assay. Results indicated that only 2 of the 5 patients, who exhibited the most severe symptoms, had true hypothyroidism. This case series demonstrates the benefits of using the free thyroxine by equilibrium dialysis when testing Sturge-Weber syndrome patients on antiepileptic medications. This testing algorithm is more cost-effective and also improves the quality of care by providing an accurate diagnosis more quickly. In addition, we propose consideration of this testing method in any patient taking anticonvulsants, most notably oxcarbazepine.
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hemiparesis is a clinical correlate of general adaptive dysfunction in children and adolescents with sturge Weber syndrome
Journal of Child Neurology, 2009Co-Authors: Jennifer Reesman, Anne M Comi, Lisa M. Ferenc, Eric H. Kossoff, Doris D M Lin, Stacy J Suskauer, Robert Gray, Elizabeth Turin, Patrick J Brice, Andrew T ZabelAbstract:This study sought to identify neurologic correlates of adaptive functioning in individuals with Sturge-Weber syndrome. A total of 18 children, adolescents, and young adults with Sturge-Weber syndrome with brain involvement were recruited from our Sturge-Weber center. All underwent neurologic examination (including review of clinical brain magnetic resonance imaging) and neuropsychological assessment. Neuropsychological assessment included measures of intellectual ability and standardized parent report of adaptive functioning. Overall, Full Scale IQ and ratings of global adaptive functioning were both lower than the population-based norms (P < .05). Negative correlations were identified between adaptive functioning ratings, clinician ratings of cortical abnormality, and ratings of neurologic status. Hemiparesis (minimal versus prominent) was the only individual component of the rating scales that differentiated between individuals with nonimpaired and impaired adaptive functioning scores. Information obtained during neurological examination of children and adolescents with Sturge-Weber syndrome particularly hemiparetic status is useful for identifying children who may need additional intervention.
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Central Hypothyroidism and Sturge- Weber Syndrome
Pediatric neurology, 2008Co-Authors: Anne M Comi, Sridevi Bellamkonda, Lisa M. Ferenc, Bernard A. Cohen, Emily L. Germain-leeAbstract:Sturge-Weber syndrome is a rare disorder manifesting with a facial port-wine birthmark and a vascular malformation of the brain. Infants and children present with seizures and stroke-like episodes with focal neurologic deficits. Our previous investigations revealed that growth-hormone deficiency occurs with an increased prevalence in Sturge-Weber syndrome, presumably secondary to involvement of the hypothalamic-pituitary axis. We have continued to screen for hormonal abnormalities in patients with Sturge-Weber syndrome, specifically those from our multidisciplinary center for patients with this condition. We describe 2 children out of 83 (2.4%) with Sturge-Weber syndrome and brain involvement who were evaluated at our center and diagnosed with central hypothyroidism, based on clinical signs and laboratory findings. This prevalence is much higher than that of central hypothyroidism in the general population. Although it is well-known that anticonvulsants can lead to abnormalities in thyroid function tests, including central hypothyroidism, patients with Sturge-Weber syndrome carry the additional risk of developing hypothalamic-pituitary dysfunction, secondary to their central nervous system dysfunction. Therefore, it is important that patients with Sturge-Weber syndrome undergo routine thyroid-function testing, especially in the face of any clinical manifestations.
Arezo Amirikia - One of the best experts on this subject based on the ideXlab platform.
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bilateral diffuse choroidal hemangiomas with unilateral facial nevus flammeus in sturge Weber syndrome
American Journal of Ophthalmology, 2000Co-Authors: Arezo Amirikia, Ingrid U. Scott, Timothy G. MurrayAbstract:PURPOSE: To report bilateral choroidal hemangiomas associated with unilateral facial nevus flammeus in Sturge-Weber syndrome. METHODS: Case report. RESULTS: A 6-year-old male with a left facial nevus flammeus and a history of a left cerebral angioma had been followed 2 years for increasing esotropia. Examination demonstrated bilateral diffuse choroidal hemangiomas with overlying exudative retinal detachments. After bilateral external beam radiotherapy, the retinal detachments resolved and vision improved. CONCLUSION: Patients with Sturge-Weber syndrome and unilateral facial nevus flammeus may harbor bilateral choroidal hemangiomas. Clinical manifestations of the Sturge-Weber syndrome are characteristically unilateral and ipsilateral to the facial nevus flammeus. Bilateral choroidal hemangiomas associated with bilateral facial nevus flammeus are rare. 1,2 We report bilateral diffuse choroidal hemangiomas associated with unilateral facial nevus flammeus in Sturge-Weber syndrome.
Danil Shaykhutdinov - One of the best experts on this subject based on the ideXlab platform.
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determination of Weber ampere characteristics of electric devices using solution of inverse problem of harmonic balance
Mathematical Models and Methods in Applied Sciences, 2015Co-Authors: Lankin Anton Mikhailovich, N I Gorbatenko, Mikhail Vladimirovich Lankin, Danil ShaykhutdinovAbstract:This work is devoted to development of measurement of Weber--ampere characteristic of electric devices consisting of a magnetic core and a coil. In this method the coil of electric device is energized with sinusoidal voltage of known amplitude and frequency, and harmonic amplitudes of passing current are measured. On the basis of these data the inverse problem of harmonic balance is solved and the approximation coefficients of the equation describing the required Weber--ampere characteristic are determined. The influence of the degree of approximating expression on measurement error is studied. The obtained results have demonstrated possibility of application of the proposed method to measurements of Weber--ampere characteristics of electric devices. The measurement error of Weber--ampere characteristic does not exceed 3 %.
