The Scattered Light Time-history Diagnostic suite at the National Ignition Facility.

The Scattered Light Time-history Diagnostic (SLTD) is being implemented at the National Ignition Facility (NIF) to greatly expand the angular coverage of absolute scattered-light measurements for direct- and indirect-drive inertial confinement fusion (ICF) experiments. The SLTD array will ultimately consist of 15 units mounted at a variety of polar and azimuthal angles on the NIF target chamber, complementing the existing NIF backscatter suite. Each SLTD unit collects and diffuses scattered light onto a set of three optical fibers, which transport the light to filtered photodiodes to measure scattered light in different wavelength bands: stimulated Brillouin scattering (350 nm-352 nm), stimulated Raman scattering (430 nm-760 nm), and ω/2 (695 nm-745 nm). SLTD measures scattered light with a time resolution of ∼1 ns and a signal-to-noise ratio of up to 500. Currently, six units are operational and recording data. Measurements of the angular dependence of scattered light will strongly constrain models of laser energy coupling in ICF experiments and allow for a more robust inference of the total laser energy coupled to implosions.

[Mobbing. Psychologic abuse in the work setting]. / Mobbing. Maltrato psicológico en el ámbito laboral.

Mobbing is a relatively recent study phenomenon, lying in the realm of abuses. It is especially well-known as a form of psychological mistreatment at the work place. It develops due to an asymmetric power relationship among 2 or more people and its fundamental essence is jealousy and the ambition to hold power by at least one of these people.

Properties of Asp212----Asn bacteriorhodopsin suggest that Asp212 and Asp85 both participate in a counterion and proton acceptor complex near the Schiff base.

The gene coding for bacteriorhodopsin was modified in vitro to replace Asp212 with asparagine and expressed in Halobacterium halobium. X-ray diffraction measurements showed that the major lattice dimension of purple membrane containing the mutated bacteriorhodopsin was the same as wild type. At pH greater than 7, the Asp212----Asn chromophore was blue (absorption maximum at 585 nm) and exhibited a photocycle containing only the intermediates K and L, i.e. a reaction sequence very similar to that of wild-type bacteriorhodopsin at pH less than 3 and the blue form of the Asp85----Glu protein at pH less than 9. Since in the latter cases these effects are attributed to protonation of residue 85, it now appears that removal of the carboxylate of Asp212 has similar consequences as removing the carboxylate of Asp85. However, an important difference is that only Asp85 affects the pKa of the Schiff base. At pH less than 7, the Asp212----Asn protein was purple (absorption maximum at 569 nm) but photoexcitation produced only 15% of the normal amount of M and the transport activity was partial. The reactions of the blue and purple forms after photoexcitation are both quantitatively accounted for by a proposed scheme, K in equilibrium with L1 in equilibrium with L2----BR, but with the addition of an L1 in equilibrium with M reaction with unfavorable pKa for Schiff base deprotonation in the purple form. The latter hinders the transient accumulation of M, and the consequent branching at L1 allows only partial proton transport activity. The results are consistent with the existence of a complex counterion for the Schiff base proposed earlier (De Groot, H. J. M., Harbison, G. S., Herzfeld, J., and Griffin, R. G. (1989) Biochemistry 28, 3346-3353) and suggest that Asp85, Asp212, and at least one other protonable residue participate in it.

A quartz cell for studying planar lipid bilayer membranes.

A quartz chamber is proposed for use in experiments with planar lipid bilayer membranes. Membranes are formed in a hole made on the lateral wall of a fused quartz test tube, immersed in an electrolyte solution. The quartz cell is easy to clean, chemically inert and easily made. Membranes formed in this chamber had specific resistances higher than 10(8) omega.cm2 and excellent mechanical stability.

Interaction of red blood cells with a polarized electrode: evidence of long-range intermolecular forces.

We have investigated the electrostatic interaction of glutaraldehyde-fixed human red cells with a polarizable electrode carrying a defined surface charge density which can be varied continuously through a wide range. Cells in a dilute salt solution are unable to adhere to the electrode at high negative charge, but at lower negative charge densities they are reversibly adherent and can be forced off by increasing the negative polarization. Near zero electrode charge they become irreversibly stuck to the electrode and cannot be evicted even at maximum electrode polarization. Calculation of the electrostatic repulsive force using measured charge densities indicates the existence of an attractive force which may be acting over several hundred angstroms.