The x-ray scattering from liquid copper, silver, tin, and mercury was measured at temperatures of 1125 °C, 1050 °C, 335 °C, and 28 °C, respectively, from the open surface of horizontal samples using a focusing theta-theta diffractometer, quartz crystal monochromator positioned in the dif fracted beam, scintillation detector, and pulse height discriminator. The effect on the measured intensities of the positioning of the sample with respect to the diffractometer axis and the meniscus of the liquid were considered. Calibration of the primary beam intensity by measurements on liquid mercury provided an alternate check of the standard normalization procedures for copper, silver, and tin. After calculation of the interference functions, atomic and radial distribution functions were evaluated from which interatomic distances and coordination numbers were obtained. The interatomic distances in the liquid were in good agreement with the G o l d s c h m id t diameters of the respective elements.X-ray diffraction is one of the more important methods that may be employed to investigate the liquid state of matter. The arrangement of the atoms determines the angular distribution of the scattered x-rays. This arrangement is usually described by the probability W {r)dv of finding the center of another atom in the volume element dt> at a distance r from a given atom. Then, W (r) = Q (r )/g 0 , where o(r) is the atomic density function and ,o0 the average atomic density in the liquid. It can be shown that, for monatomic liquids, the radial distribution func tion (R D F ) 4 ; r r 2 o(r) is given by1: 4 n r2 Q (r) = 4 n r2 o0 o o + (2 r/ji) f K [ I ( K ) -l]-(sin£r) d K ,(1 ) o where K = 2 ji s = 4 ji sin © //, s = 2 sin G/X, and I( K ) is the interference function:

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Background and Purpose— Familial hemiplegic migraine is characterized by recurrent migraine, hemiparesis, and ataxia. Causes may be mutations in calcium and sodium channels or in a subunit of the Na/K-ATPse. Migraine treatment with calcium channel blockers was only successful in some patients. Summary of Case— We describe a 6-year-old girl with recurrent ischemic strokes after minor head trauma associated with seizures, hemiparesis, fever, and altered consciousness. Genetic analysis revealed a spontaneous, novel dominant CACNA1A mutation (c.4046G→A, p.R1349Q) that removed a highly conserved arginine of the voltage sensing region of the P/Q-type Ca v 2.1 channel. Because a homologous mutation in the tottering-5J mouse increased open probability of the channel as well as calcium influx, we treated the patient with the calcium channel blocker verapamil during characteristic prodromi after head trauma. Treatment was instantly effective and prevented a new stroke. Conclusion— CACNA1A mutations should be considered in the diagnostic workup of childhood stroke, especially if associated with ataxia and migraine.

Twin faults may be detected from diffraction patterns of fcc metals and alloys by two existing methods: (1) from the sine coefficients of a one-dimensional Fourier series representing the peak, and (2) from the excess intensity between two peaks which are asymmetric in opposite directions, such as the 111 and 200. However, the contribution of twin faults to the particle size measured by Fourier analysis appears too large when the fault probabilities are determined by these methods. A third technique has been developed based on the displacement of the center of gravity of a peak from the peak maximum, ΔC.G. The displacements for the 111 and 200 peaks are related to the twin fault probability β: ΔC.G. (∘2θ)111=+11β tanθ111ΔC.G. (∘2θ)200=−14.6β tanθ200. By using two peaks, such as the 111 and 200, the difficult choice of background and instrumental effects can be minimized. A comparison of the three techniques is presented. As a consequence of the new method, it is clear that the probability of deformation stacking faults (α) should be measured from the displacements of peak maxima from those of an annealed specimen; if the C.G. is used and twin faults are present, a large error is possible.