2,878 research outputs found

    Functional and anatomic correlates of two frequently observed temporal lobe seizure-onset patterns.

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    Intracranial depth electrode EEG records of 478 seizures, recorded in 68 patients undergoing diagnostic monitoring with depth electrodes, were evaluated to investigate the correlates of electrographic onset patterns in patients with temporal lobe seizures. The seizure onsets in 78% of these patients were identified as either hypersynchronous onsets, beginning with low-frequency, high-amplitude spikes, or low-voltage fast (LVF) onsets, increasing in amplitude as the seizure progressed. The number of patients (35) having hypersynchronous seizure onsets was nearly twice that of patients (18) having LVF onsets. Three major differences were seen among patients with the two seizure-onset patterns. When compared with patients having LVF onsets, patients with hypersynchronous seizure onsets had a significantly greater probability of having (1) focal rather than regional seizure onsets (p < 0.01), (2) seizures spreading more slowly to the contralateral mesial temporal lobe (p < 0.003), and (3) cell counts in resected hippocampal tissue showing greater neuronal loss (p < 0.001). The results provide evidence that the most frequent electrographic abnormality associated with mesial temporal seizures is local hypersynchrony, a condition associated with major neuronal loss in the hippocampus. The results also indicate that LVF seizure onsets more frequently represent widely distributed discharges, which interact with and spread more rapidly to surrounding neocortical areas

    Ultracold collisions of metastable helium atoms

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    We report scattering lengths for the singlet Sigma g +, triplet Sigma u + and quintet Sigma g + adiabatic molecular potentials relevant to collisions of two metastable (n=2 triplet S) helium atoms as a function of the uncertainty in these potentials. These scattering lengths are used to calculate experimentally observable scattering lengths, elastic cross sections and inelastic rates for any combination of states of the colliding atoms, at temperatures where the Wigner threshold approximation is valid.Comment: 20 pages, 8 figures, RevTeX, epsf. Small additions of tex

    Women and War: St. Petersburg Women During World War II

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    During World War II, government agencies and private businesses recruited millions of American women for employment in wartime industries and in other nontraditional fields when the nation’s young men left for war. Government propaganda, national periodicals, and local newspapers worked in unison to promote female employment, and popular songs like “Rosie the Riveter” inspired allegiance on the home front. In a radical departure from previously sanctioned public behavior, older, married women— many with children— entered the country’s labor force en masse. Even though millions of women stepped well beyond previously accepted boundaries of home and “women’s sphere” during World War II, recruitment campaigns continued to define women’s new roles in domestic terms, reinforcing expectations that women would relinquish their wartime positions to veterans when peace returned

    Variational calculations on the hydrogen molecular ion

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    We present high-precision non-relativistic variational calculations of bound vibrational-rotational state energies for the H2+H_2^+ and D2+D_2^+ molecular ions in each of the lowest electronic states of Σg\Sigma_g, Σu\Sigma_u, and Πu\Pi_u symmetry. The calculations are carried out including coupling between Σ\Sigma and Π\Pi states but without using the Born-Oppenheimer or any adiabatic approximation. Convergence studies are presented which indicate that the resulting energies for low-lying levels are accurate to about 10−1310^{-13}. Our procedure accounts naturally for the lambda-doubling of the Πu\Pi_u state.Comment: 23 pp., RevTeX, epsf.sty, 5 figs. Enhanced data in Table II, dropped 3 figs. from previous versio

    Theory and simulation of spectral line broadening by exoplanetary atmospheric haze

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    Atmospheric haze is the leading candidate for the flattening of expolanetary spectra, as it's also an important source of opacity in the atmospheres of solar system planets, satellites, and comets. Exoplanetary transmission spectra, which carry information about how the planetary atmospheres become opaque to stellar light in transit, show broad featureless absorption in the region of wavelengths corresponding to spectral lines of sodium, potassium and water. We develop a detailed atomistic model, describing interactions of atomic or molecular radiators with dust and atmospheric haze particulates. This model incorporates a realistic structure of haze particulates from small nano-size seed particles up to sub-micron irregularly shaped aggregates, accounting for both pairwise collisions between the radiator and haze perturbers, and quasi-static mean field shift of levels in haze environments. This formalism can explain large flattening of absorption and emission spectra in haze atmospheres and shows how the radiator - haze particle interaction affects the absorption spectral shape in the wings of spectral lines and near their centers. The theory can account for nearly all realistic structure, size and chemical composition of haze particulates and predict their influence on absorption and emission spectra in hazy environments. We illustrate the utility of the method by computing shift and broadening of the emission spectra of the sodium D line in an argon haze. The simplicity, elegance and generality of the proposed model should make it amenable to a broad community of users in astrophysics and chemistry.Comment: 16 pages, 4 figures, submitted to MNRA
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