Family Carabodidae (Acari: Oribatida) V. The genus Congocepheus Balogh, 1958 (second part), with a redescription of Congocepheus involutus Mahunka, 1997, and descriptions of two new species

The species Congocepheus involutus Mahunka, 1997 is redescribed, and two newspecies are described, Congocepheus gabonensis n. sp. and Congocepheus ektactesin. sp., using optical and scanning electron microscopy.La Famille Carabodidae (Acari: Oribatida) V. Le genre Congocepheus, Balogh, 1958 (deuxième partie) avec la redescription de Congocepheus involutus Mahunka, 1997 et les descriptions de deux nouvelles espèces. L'espèce Congocepheus involutus Mahunka, 1997 est redécrite et deux espèces nouvelles sont décrites Congocepheus gabonensis n. sp. et Congocepheus ektactesi n. sp. sur la base d'observations en microscopie optique et électronique à balayage.Fil: Fernandez, Nestor Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Rioja; ArgentinaFil: Theron, Pieter. North-West University; SudáfricaFil: Rollard, Christine. Centre National de la Recherche Scientifique; Francia. Museum National D; FranciaFil: Tiedt, Louvrens. North-West University; Sudáfric

A liquid crystal analogue of the cosmic string

We consider the propagation of light in a anisotropic medium with a topological line defect in the realm of geometrical optics. It is shown that the effective geometry perceived by light propagating in such medium is that of a spacial section of the cosmic string spacetime.Comment: 3 pages, 2 figures. Modern Physics Letters A, accepted for publicatio

On the Kelvin Electrostatic Generator

The Kelvin generator is an amazing electrostatic device which poses many questions. The authors report the results of their investigations of this device under various controlled conditions with both nonpolar and polar liquids and a sodium chloride aqueous solution. They have found that the generator works well even if the two liquid streams originate from different electrically insulated reservoirs. In addition they propose a model in which the electric charge results from the separation of the hydrogen and hydroxyl ions as the water droplets form

Characterization of non-aged and aged modern Prussian Blue pigments by Mössbauer spectroscopy, x-ray powder diffraction and x-ray absorption spectroscopy

C

Valuing Access to our Public Lands: A Unique Public Good Pricing Experiment

We report the findings of a unique nation-wide experiment to price access to our public lands. In 2004, the U.S. Federal Lands Recreation Enhancement Act mandated the creation of a new annual pass to cover all federal recreation sites that charge an entrance or access fee. Our task was to assist federal policymakers in determining an appropriate price for this new pass. Toward that end, we administered a contingent valuation phone survey to over 3700 households to estimate households willingness to pay (WTP) for the new pass at a variety of different prices. Our innovative experimental design allows us to estimate the degree of hypothetical bias in the sample and calibrate our WTP estimates to reflect actual purchasing decisions. In a sample of the general U.S. population most of whom have little experience with similar federal passes respondents tend to greatly exaggerate their WTP for the pass when contrasted with previous pass sales. A sample of recent pass purchasers, however, exhibits little bias. This confirms recent research showing that market experience can be an effective means to mitigate hypothetical bias.Land Economics/Use,

Large K-exciton dynamics in GaN epilayers: the non-thermal and thermal regime

We present a detailed investigation concerning the exciton dynamics in GaN epilayers grown on c-plane sapphire substrates, focussing on the exciton formation and the transition from the nonthermal to the thermal regime. The time-resolved kinetics of LO-phonon replicas is used to address the energy relaxation in the excitonic band. From ps time-resolved spectra we bring evidence for a long lasting non-thermal excitonic distribution which accounts for the rst 50 ps. Such a behavior is con rmed in di erent experimental conditions, both when non-resonant and resonant excitation are used. At low excitation power density the exciton formation and their subsequent thermalization is dominated by impurity scattering rather than by acoustic phonon scattering. The estimate of the average energy of the excitons as a function of delay after the excitation pulse provides information on the relaxation time, which describes the evolution of the exciton population to the thermal regime.Comment: 9 pages,8 figure

Antioxidative enzyme activities in human erythrocytes.

Reliable and standardized methods are necessary to determine the expression of antioxidative enzymes and their role in maintaining health. In addition, the variability of the enzyme activities within the general population caused by age, gender, and life-style factors must be described. This study describes methodological conditions that are suitable for analyzing copper–zinc superoxide dismutase (CuZn-SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and glutathione reductase (GR) in human erythrocytes with a high degree of reproducibility. Intervals for the enzyme activities have been established in a randomly selected population of 220 individuals between 20 and 89 years of age. An age-related decrease was observed in CuZn-SOD and GR activities, whereas no age-related changes were demonstrated for GSH-Px and CAT. The GSH-Px activity was positively associated with the intake of dietary supplements and negatively correlated with tobacco consumption. These factors probably account for the fact that women tended to have higher GSH-Px activity

Cavity-enhanced optical Hall effect in two-dimensional free charge carrier gases detected at terahertz frequencies

The effect of a tunable, externally coupled Fabry-P\'{e}rot cavity to resonantly enhance the optical Hall effect signatures at terahertz frequencies produced by a traditional Drude-like two-dimensional electron gas is shown and discussed in this communication. As a result, the detection of optical Hall effect signatures at conveniently obtainable magnetic fields, for example by neodymium permanent magnets, is demonstrated. An AlInN/GaN-based high electron mobility transistor structure grown on a sapphire substrate is used for the experiment. The optical Hall effect signatures and their dispersions, which are governed by the frequency and the reflectance minima and maxima of the externally coupled Fabry-P\'{e}rot cavity, are presented and discussed. Tuning the externally coupled Fabry-P\'{e}rot cavity strongly modifies the optical Hall effect signatures, which provides a new degree of freedom for optical Hall effect experiments in addition to frequency, angle of incidence and magnetic field direction and strength