Retraction: Sylvian Fissure Lipoma: An Unusual Etiology of Seizures in Adults.

[This retracts the article DOI: 10.7759/cureus.21407.].

Sylvian Fissure Lipoma: An Unusual Etiology of Seizures in Adults.

Seizure is a prevalent symptom and is an important neurological complaint in the emergency department. Patients with first-time seizures require a thorough evaluation to determine the possible etiologies and identify any causative pathology. Further, neuroimaging studies are vital to identifying the structural culprits. We report the case of a 35-year-old man who was brought to the emergency department with abnormal repetitive shaking movements that were witnessed by his spouse. Before the event, he became dizzy and fell to the ground. During the episode, he was not aware of his surrounding. He developed uprolling of his eyes and had frothy secretions from the mouth. On physical examination, the patient was drowsy but fully oriented. There were no signs of focal neurological deficit. Routine laboratory investigations, including hematological and biochemical profiles, yielded normal results. He was referred to undergo magnetic resonance imaging of the brain. The scan demonstrated the presence of a well-circumscribed lesion in the left Sylvian fissure with high signal intensity on T1- and T2-weighted image with suppression on the fat-suppressed sequence and no post-contrast enhancement. The radiological impression was of Sylvian fissure lipoma. The lesion was successfully resected surgically and the patient had an uneventful recovery with no complaints at the follow-up visits. Sylvian fissure lipoma is among the rarest locations of intracranial lipoma. Despite this, physicians should remember this lesion when they encounter a brain lesion with high signal intensity on T1- and T2-weighted images. While the majority of cases are incidental, an intracranial lipoma can be an etiology of first-time seizures in adults.

Imaging and radiometric properties of microlens arrays.

The imaging and radiometric properties of erect lens arrays made up of small biconvex microlenses are derived from a ray analysis. The lens arrays provide erect, unit magnification images. The relationship between the radii of curvature, the lens thickness, and the one-to-one conjugate distance is derived for both the single-layer case and a double-layer structure, which contains field lenses. Radiometric properties of the microlens and the array are derived for both structures. The results are compared to experimentally measured values obtained from arrays fabricated by a photothermal process.

Theoretical model of visible radiation from rare gas flashlamps.

A simple theoretical model of visible light emission from xenon flashlamps is presented. The continuum light emission is calculated from the rate of electron-ion recombination in the xenon plasma, which is treated as a greybody in thermal equilibrium. The effect of radiation reabsorption is calculated in terms of the temperature-dependent greybody emissivity. The model predictions of radiated power and energy are compared to measured data. Reasonable agreement is obtained over a wide range of parameters of practical interest. Thus the model provides a useful analytical tool for first-order engineering design of xenon flash-lamp illumination systems.

Analytical model for low-pressure gas discharges: application to the Hg + Ar discharge.

A general technique for analyzing complicated gas discharges has been developed and applied to the Hg + Ar (fluorescent lamp) discharge. The theoretical model includes electron excitation and deexcitation, two-state ionization through a saturated metastable level, and proper treatment of the self-absorption of the resonance radiation. The analysis yields simple analytic expressions for the electron temperature, the resonance radiation, and the electric field. When applied to Hg + Ar discharges, these analytic expressions yield good quantitative agreement with the available absolute data on the dependence of the electron temperature, the Hg 2537-A radiation, and the electric field on mercury pressure and current.

Optical properties of GRIN fiber lens arrays: dependence on fiber length.

The optical imaging and radiometric properties of arrays of GRIN fiber lenses (Selfoc lens arrays) have been studied as a function of the length of the fibers. Experiments measured the object-to-image distance, image quality (MTF), depth of focus, image irradiance distribution, and exposure for a set of Selfoc lenses with differing fiber length. Simple models were used to explain the observed dependences, and analytical formulas were developed for the prediction of these optical properties.

Arc-acoustic interaction in rare gas flashlamps.

High frequency oscillations have been observed in rare gas flashlamp voltage and light output pulses. Experiments have shown that the frequency of the oscillations increases with the square root of the input electrical energy density. At fixed energy density input, the period of the oscillations increases linearly with the cylindrical lamp radius and with the square root of the atomic mass of the rare gas. These measured dependences suggest an acoustic generation mechanism with the gas temperature proportional to the input energy density. This interpretation allows a determination of the instantaneous gas temperature from the measured oscillation frequency.

Some radiometric properties of gradient-index fiber lenses.

Some radiometric properties of gradient-index fiber lenses and lens arrays are explored. Consideration is restricted to the paraxial region of fibers that produce erect images at unit magnification. In two instances the radiometric properties of these lenses and lens arrays are considerably different from the properties of conventional (nongradient) lenses. First, the off-axis image plane irradiance for a single gradient-index fiber falls off far more rapidly than the familiar cos(4) law. Second, the exposure (integrated image irradiance) for a fiber array is independent of the object-to-image distance.