Resonant optical second harmonic generation and mixing

Experimental and theoretical results are described on the enhancement of optical second harmonic generation (SHG) and mixing in KDP by the use of optical resonance. Both resonance of the harmonic and of the fundamental are considered. Large enhancements are possible for resonators with low loss. Using a planoconcave harmonic resonator containing 1.23 cm of KDP, the authors achieved a loss < 4 percent per pass. This resulted in an enhancement of ∼ 500 times the harmonic power internal to the resonator and ∼ 10 times external to the resonator. When resonating, the fundamental enhancements of ∼ 5 were observed. The theory includes the effect of double refraction. This results in a coupling coefficient of the generated harmonic power to the transverse modes of the harmonic resonator. The experimental results are in substantial agreement with the theory.     

On the status of nonconscious processes in human cognition: Comment on Reber.

Two issues are discussed. The first one pertains to the generality of the nonconscious learning processes and their somewhat paradoxical status in cognitive psychology. We argue that the ability of the human cognitive system to nonconsciously acquire complex knowledge structures is one of its elementary and indispensable properties. Moreover, the existence of this ability constitutes one of the necessary metatheoretical assumptions of contemporary cognitive psychology. Nevertheless, the contemporary cognitive psychology literature often implies that it is only one of many controversial and unusual phenomena. The second issue pertains to the distinction between the so-called primitive unconscious and the sophisticated unconscious as proposed by A. S. Reber (see record 1989-38920-001). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Structural and electrical properties of perovskite ruthenate-based lead-free thick film resistors on alumina and LTCC

CaRuO₃ perovskite-based lead-free thick-film resistors (TFRs) were prepared on 96%-alumina and Low Temperature Co-fired Ceramic (LTCC) substrates. The microstructure evolution, possible interactions, and electrical properties of resistors were investigated. The hot and cold TCR values of all the resistors were measured in the temperature range (+20 to +120 ^∘C) and (+20 to −120 ^∘C), respectively. TFRs with 25% by vol. of CaRuO₃ on alumina exhibit a sheet resistance R_s = 5kΩ/sq. with hot and cold TCR of 225 and 470 ppm/^∘C respectively, whereas the same composition gives 1.2 kΩ/sq., 16.5 kΩ/sq. and 0.7 kΩ/sq. for co-fired, post-fired resistors on LTCC and buried resistors, respectively. The hot (HTCR) and cold (CTCR) values were evaluated; HTCR = 190 ppm/^∘C and CTCR = 314 ppm/^∘C were found for co-fired structures; HTCR = 216 ppm/^∘C and CTCR = 205 ppm/^∘C for post-fired samples and HTCR = 520 ppm/^∘C and CTCR = 350 ppm/^∘C for buried in LTCC structures.     

Deflection of nanotubes in response to external atomic collisions

The mechanical response of single-walled and multiwalled carbon nanotubes to a series of external Ar atom impacts is examined with classical molecular dynamics simulations. The extent to which the carbon nanotubes deform in the direction perpendicular to their axis is found to depend on the amount of momentum transferred during the collisions. The details of the mechanical response and recovery of the nanotubes after release are also found to depend on the nanotube configurations.     

Two-Machine Stochastic Flow Shops With Blocking and the Traveling Salesman Problem

The paper deals with the problem of minimizing the expected makespan in a two-machine flow shop with blocking and random job processing times. It is well known that it reduces to an instance of the traveling salesman problem (TSP). Assuming that the job processing times can be stochastically ordered on both machines, we show that the problem under study is equivalent to TSP on a permuted Monge matrix. This allows us to prove that it is NP-hard for the independently and exponentially distributed job processing times, and identify a new class of efficiently solvable special cases.     

Polymerization of chlorophenyl glycidyl ethers. VI

Summary Polymerization of p-chlorophenyl glycidyl ether initiated by potassium glycolates (ethylene, propylene and 2-methyl propylene glycolatea) in DMSO containing some 18-crown-6 ether or glycol was investigated. For the reaction system containing the propylene glycolate asymmetrically substituted with a methyl group, relatively high polymerization rates were obtained as compared with those found for the other systems studied, the resultant polymers also having higher molecular weights and comparatively low polydispersities. Aliphatic double bonds were found to be absent in the polymers synthesized, which would suggest that in the anionic polymerization process studied the growing chain is not transferred to the monomer.Dedicated to Prof. C.I. Simionescu on the occasion of the 60th anniversary of his birthday