Defining Stream Fish Microhabitat Requirements for Water Project Planning

Brown trout daily activities were divided into two braod categories, resting and feeding, and the population was divided into three size groups (one of which is reported on here), based on the timing and location of these activities. Microhabitat components, measured previously in four rivers at sites occupied by fish, were utilized to develop usable componenet ranges for each size group and activity to illustrate the breadth of component values utilized out of the total range available. Microhabitat is thus described as a range of numerical values for each componenet of a specific set of components. A 90 meter section of the Blacksmith Fork River in northern Utah was mapped by measuring depth, current velocity and light. A scuba diver searched the area, locating and identifying brown trout according to size group and activity. A comparison of fish locations with the mpas indicates the maps correctly identified a high percentage of the sites occupied by brown trout. A chi-square test of the probability of uniform distribution of fish was significant for both feeding and resting sites. Microhabitat components which most effectively regulate brown trout distribution in this type of intermountain strean can thus be described and measured, and used to estimate the porportion of a stream which is habitable. These quantified components should enable the designing of stream channel alterations to provide proper trout microhabitat

Magnetism in Graphene Induced by Single-Atom Defects

We study from first principles the magnetism in graphene induced by single carbon atom defects. For two types of defects considered in our study, the hydrogen chemisorption defect and the vacancy defect, the itinerant magnetism due to the defect-induced extended states has been observed. Calculated magnetic moments are equal to 1 $\mu_B$ per hydrogen chemisorption defect and 1.12$-$1.53 $\mu_B$ per vacancy defect depending on the defect concentration. The coupling between the magnetic moments is either ferromagnetic or antiferromagnetic, depending on whether the defects correspond to the same or to different hexagonal sublattices of the graphene lattice, respectively. The relevance of itinerant magnetism in graphene to the high-$T_C$ magnetic ordering is discussed.Comment: 5 pages, 6 figure

Field Dependence of the Josephson Plasma Resonance in Layered Superconductors with Alternating Junctions

The Josephson plasma resonance in layered superconductors with alternating critical current densities is investigated in a low perpendicular magnetic field. In the vortex solid phase the current densities and the squared bare plasma frequencies decrease linearly with the magnetic field. Taking into account the coupling due to charge fluctuations on the layers, we extract from recent optical data for SmLa_{1-x} Sr_x CuO_{4-delta} the Josephson penetration length lambda_{ab} approximately 1100 A parallel to the layers at T=10 K.Comment: 5 pages, 6 eps-figures, final version with minor misprints correcte