Interferometry of hyper-Rayleigh scattering by inhomogeneous thin films

The use of specific symmetry properties of the optical second-harmonic generation (the s,s-exclusion rule) has allowed us to observe high-contrast hyper-Rayleigh interference patterns in a completely diffuse light - an effect having no analog in case of linear (Rayleigh) scattering.Comment: 8 pages, 3 figure

Spin Triplet Supercurrent in Co/Ni Multilayer Josephson Junctions with Perpendicular Anisotropy

We have measured spin-triplet supercurrent in Josephson junctions of the form S/F'/F/F'/S, where S is superconducting Nb, F' is a thin Ni layer with in-plane magnetization, and F is a Ni/[Co/Ni]n multilayer with out-of-plane magnetization. The supercurrent in these junctions decays very slowly with F-layer thickness, and is much larger than in similar junctions not containing the two F' layers. Those two features are the characteristic signatures of spin-triplet supercurrent, which is maximized by the orthogonality of the magnetizations in the F and F' layers. Magnetic measurements confirm the out-of-plane anisotropy of the Co/Ni multilayers. These samples have their critical current optimized in the as-prepared state, which will be useful for future applications.Comment: 4 pages, 4 figures, formatted in RevTeX version 4. Submitted to Physical Review B on August 13th, 201

The stochastic matching problem

The matching problem plays a basic role in combinatorial optimization and in statistical mechanics. In its stochastic variants, optimization decisions have to be taken given only some probabilistic information about the instance. While the deterministic case can be solved in polynomial time, stochastic variants are worst-case intractable. We propose an efficient method to solve stochastic matching problems which combines some features of the survey propagation equations and of the cavity method. We test it on random bipartite graphs, for which we analyze the phase diagram and compare the results with exact bounds. Our approach is shown numerically to be effective on the full range of parameters, and to outperform state-of-the-art methods. Finally we discuss how the method can be generalized to other problems of optimization under uncertainty.Comment: Published version has very minor change

Effect of Magnetic Impurities on Energy Exchange between Electrons

In order to probe quantitatively the effect of Kondo impurities on energy exchange between electrons in metals, we have compared measurements on two silver wires with dilute magnetic impurities (manganese) introduced in one of them. The measurement of the temperature dependence of the electron phase coherence time on the wires provides an independent determination of the impurity concentration. Quantitative agreement on the energy exchange rate is found with a theory by G\"{o}ppert et al. that accounts for Kondo scattering of electrons on spin-1/2 impurities.Comment: 4 page

Embryopathic Effects of Waterborne and Sediment-Accumulated Cadmium, Mercury and Zinc on Reproduction and Survival of Fish and Amphibian Populations in Kentucky

Fish and amphibian egg cultures were used to determine the embryopathic effects of cadmium, mercury, and zinc released from natural and metal-enriched sediments, and to develop egg culture bioassay procedures suitable for monitoring bottom sediments for hazardous contaminants. Eggs of the narrow-mouthed toad (Gastrophryne carolinensis), goldfish (Carassius auratus), and rainbow trout (Salmo gairdnei) were cultured in contaminant-free water added to natural and metal-enriched sediments. Exposure was initiated after fertilization (toad, goldfish) or at 10 days prehatching (trout) and maintained continuously through 4-10 days posthatching. Sediments were enriched with 0.1-100 ppm cadmium and mercury and 1.0-1000 ppm zinc. Natural control sediments contained average concentrations of 0.052 ppm mercury, 1.0 ppm cadmium, and 108.2 ppm zinc. Substantial frequencies of mortality and teratogenesis occurred for all 3 animal species when eggs were cultured over natural elements further enriched with as little as 0.1-1.0 ppm cadmium or mercury and 1-10ppm zinc. Survival of trout embryos and alevins closely paralleled sediment test concentrations. The sediment TL50 concentrations for trout stages cultured from 10 days prehatching through 10 days posthatching were approximately 1ppm for mercury, 2.15 ppm for cadmium, and 210.6 ppm for zinc. Sediment metals were substantially more lethal to eggs and embryos than to free-living larvae or fry

The Aquatic Toxicity of Organic Compounds to Embryo-Larval Stages of Fish and Amphibians

Aquatic toxicity tests were conducted on 11 organic compounds considered hazardous to water resources. The toxicity of each compound was evaluated using embryo-larval stages of two to eight fish and amphibian species. Exposure was initiated at fertilization and maintained through 4 days posthatching. The animal test species exhibited varying degrees of sensitivity to the selected toxicants. Combined frequencies for mortality and teratogenesis at 4 days posthatching gave LC50 ranges of 3.66 to 8.25 mg/L for benzene, 1.16 to 22.42 mg/L for carbon tetrachloride, 0.11 to 1.20 mg/L for chlorobenzene, 2.03 to \u3e 68 mg/L for chloroform, 3.01 to 5.56 mg/L for 1,2-dichlorobenzene, 2.54 to .34 mg/L for 1,2-dichloroethane, 13.16 to \u3e 48 mg/L for methylene chloride, 0.002 to 0.64 mg/L for nitrobenzene, 0.04 to .32 mg/L for phenol, 0.02 to 0.85 mg/L for toluene, and 3.53 to 3.77 mg/L for m-xylene. The species which exhibited the greatest susceptibility to organic compounds were the rainbow trout, Rana pipiens, and Rana temporaria. The more sensitive amphibian species generally were those which normaly are restricted to aquatic or moist terrestrial habitats, whereas the more tolerant amphibians included those semi-aquatic and terrestrial species which appear to be more broadly adapted ecologically. Of the 11 test compounds, nitrobenzene, toluene, chlorobenzene, and phenol were the most toxic. The least toxic organics included dichloroethane and methylene chloride. For three chlorinated alkanes, including methylene chloride (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), toxicity was found to 1ncrease with the degree of chlorination. Concerning several aromatic hydrocarbons, benzene always was found to be less toxic than its monosubstituted analogs. Toxicity of the 11 compounds was further evaluated by calculating toxicant concentrations which produced embryo-larval mortality and/or teratogenesis at frequencies of 10% (LC10) and 1% (LC1). The LC values, used to estimate toxicity thresholds, ranged from \u3c 0.l for nitrobenzene to 69.9 μg/L for methylene chloride. A limited number of toxicity tests were performed to determine whether embryo-larval bioassays are suitable to assess effects of transitory chemical exposures, such as those resulting from intermittent discharges or accidental spills of chemicals into water resources. Results indicated that Rana pipiens embryos were sufficiently sensitive to quantify effects produced by short-term exposures to chloroform. Animals tested during the earliest embryonic stage appeared to be less tolerant than organisms exposed later in development

Observation of Fluctuation-Dissipation-Theorem Violations in a Structural Glass

The fluctuation-dissipation theorem (FDT), connecting dielectric susceptibility and polarization noise was studied in glycerol below its glass transition temperature Tg. Weak FDT violations were observed after a quench from just above to just below Tg, for frequencies above the alpha peak. Violations persisted up to 10^5 times the thermal equilibration time of the configurational degrees of freedom under study, but comparable to the average relaxation time of the material. These results suggest that excess energy flows from slower to faster relaxing modes.Comment: Improved discussion; final version to appear in Phys. Rev. Lett. 4 pages, 5 PS figures, RevTe

Balancing stability and flexibility in adaptive governance: an analysis of tools available in U.S. environmental law

Adaptive governance must work “on the ground,” that is, it must operate through structures and procedures that the people it governs perceive to be legitimate and fair, as well as incorporating processes and substantive goals that are effective in allowing social-ecological systems (SESs) to adapt to climate change and other impacts. To address the continuing and accelerating alterations that climate change is bringing to SESs, adaptive governance generally will require more flexibility than prior governance institutions have often allowed. However, to function as good governance, adaptive governance must pay real attention to the problem of how to balance this increased need for flexibility with continuing governance stability so that it can foster adaptation to change without being perceived or experienced as perpetually destabilizing, disruptive, and unfair. Flexibility and stability serve different purposes in governance, and a variety of tools exist to strike different balances between them while still preserving the governance institution’s legitimacy among the people governed. After reviewing those purposes and the implications of climate change for environmental governance, we examine psychological insights into the structuring of adaptive governance and the variety of legal tools available to incorporate those insights into adaptive governance regimes. Because the substantive goals of governance systems will differ among specific systems, we do not purport to comment on what the normative or substantive goals of law should be. Instead, we conclude that attention to process and procedure (including participation), as well as increased use of substantive standards (instead of rules), may allow an increased level of substantive flexibility to operate with legitimacy and fairness, providing the requisite levels of psychological, social, and economic stability needed for communities to adapt successfully to the Anthropocene

Single-machine scheduling with stepwise tardiness costs and release times

We study a scheduling problem that belongs to the yard operations component of the railroad planning problems, namely the hump sequencing problem. The scheduling problem is characterized as a single-machine problem with stepwise tardiness cost objectives. This is a new scheduling criterion which is also relevant in the context of traditional machine scheduling problems. We produce complexity results that characterize some cases of the problem as pseudo-polynomially solvable. For the difficult-to-solve cases of the problem, we develop mathematical programming formulations, and propose heuristic algorithms. We test the formulations and heuristic algorithms on randomly generated single-machine scheduling problems and real-life datasets for the hump sequencing problem. Our experiments show promising results for both sets of problems