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Ectopia lentis (EL) is a zonular disease where alteration of the zonular fibers leads progressively to lens dislocation. It is most often associated with systemic diseases such as Marfan syndrome, Weill-Marchesani syndrome or homocystinuria. Isolated non syndromic ectopia lentis (IEL) is reported in families with autosomal inheritance, with dominant forms being more common than recessive. LTBP2 truncating mutations have been described as a cause of autosomal recessive ectopia lentis as a primary or secondary feature in patients showing ocular (eg, glaucoma) or extraocular manifestations (eg, Marfanoid habitus). Recently, ADAMTSL4 has been shown to be responsible for isolated autosomal recessive ectopia lentis in an inbred family. Herein we show a consanguineous family that carries a novel homozygous splice mutation IVS4-1G>A/IVS4-1G>A in ADAMTSL4 responsible for isolated autosomal recessive EL, thus confirming the involvement of this gene in this condition and underlining the major role of ADAMTS proteases in zonular fibers homeostasis. [ABSTRACT FROM AUTHOR]

The absorption of sound in water and in sea water has been measured in the frequency range 120 kc to 1000 kc. The fresh water values were obtained in a lake; the sea water values in the ocean. The fresh water absorption values when extrapolated as the square of the frequency are in agreement with previous values measured in the laboratory at considerably higher frequencies. It is shown that the observed absorption of water has its origin in viscous dissipation; the calculated values for the absorption agree with the observed if recently measured values for the dilatational viscosity as well as the shear viscosity are included in the calculation. The absorption processes in sea water are different. At frequencies below 100 kc the absorption is about 100 times greater than in pure water. Above 1 megacycle the absorptions are similar. It is shown that this behavior can be accounted for by introducing a relaxation mechanism with a relaxation time of 10-6 second. The nature of the relaxation mechanism is not known for certain. The proposal is made that it involves the ionic dissociation of sodium chloride in solution. Calculations are made to show that this process is a possibility. [ABSTRACT FROM AUTHOR]

Information on the instantaneous sea surface reflectivity for 30-kc sound has been obtained. The method required that the submerged source and receiver be rigidly mounted on towers resting on the sea bottom. Transmission of a frequency-modulated sound pulse results in an interference pattern at the receiver; interference occurs between the direct and reflected sound. Analysis of these interference patterns reveals the following: The average time of persistence of the pattern is five-hundredths of a second. Under the conditions of the experiment, surface reflectivity is highly frequency dependent. The median value for the reflection coefficient is near to unity. Approximately 10 percent of the time the sea surface focuses the sound, giving a a reflection coefficient greater than unity. [ABSTRACT FROM AUTHOR]

An experimental method has been developed for measuring the reflection coefficient of the ocean bottom for supersonic sound at grazing incidence. In this method the geometry is controlled so that the resultant of the direct and reflected rays passes through consecutive maxima and minima at the hydrophone. The amplitude reflection coefficient is given by the expression (M - m)/(M + m), where M is the amplitude of a maximum and m is the amplitude of the following minimum. Using this method, with a grazing angle of nine degrees, the following values were obtained for the reflection coefficients at 17 stations near Woods Hole: mud-0 to 0.20, mud-sand-0.20 to 0.40, sand-mud-0.40 to 0.60, sand-0.40 to 0.85, stony-0.50 to 0.85. It is observed that the reflection coefficient depends not only on the median size of the particles making up the bottom, but also on the sorting of the particles and on the bottom topography. [ABSTRACT FROM AUTHOR]

In the past, underwater acoustic data have been obtained with pressure-sensitive hydrophones, which neglect the particle displacement in an acoustic wave. Displacement reception possesses certain advantages, among which are the possibilities of direction finding and also of acoustic observations at the sea surface. The theory of operation of a displacement hydrophone is discussed and the technique is given for constructing instruments sensitive to a displacement of 0.1 Å at 1000 cps. The propagation of displacement observed at sea is compared with theoretical predictions. The vertical component of displacement is found to be maximum on the sea surface as predicted; the horizontal component vanishes at the sea surface, but at greater depths can be used to observe the wave-propagation direction. At short ranges, the acoustic-displacement field is closely approximated by a dipole source; at longer ranges, the displacement field diminishes less rapidly (1/r dependence) than is predicted by the dipole theory. [ABSTRACT FROM AUTHOR]