The scaling properties of dissipation in incompressible isotropic three-dimensional magnetohydrodynamic turbulence

The statistical properties of the dissipation process constrain the analysis of large scale numerical simulations of three dimensional incompressible magnetohydrodynamic (MHD) turbulence, such as those of Biskamp and Muller [Phys. Plasmas 7, 4889 (2000)]. The structure functions of the turbulent flow are expected to display statistical self-similarity, but the relatively low Reynolds numbers attainable by direct numerical simulation, combined with the finite size of the system, make this difficult to measure directly. However, it is known that extended self-similarity, which constrains the ratio of scaling exponents of structure functions of different orders, is well satisfied. This implies the extension of physical scaling arguments beyond the inertial range into the dissipation range. The present work focuses on the scaling properties of the dissipation process itself. This provides an important consistency check in that we find that the ratio of dissipation structure function exponents is that predicted by the She and Leveque [Phys. Rev. Lett 72, 336 (1994)] theory proposed by Biskamp and Muller. This supplies further evidence that the cascade mechanism in three dimensional MHD turbulence is non-linear random eddy scrambling, with the level of intermittency determined by dissipation through the formation of current sheets.Comment: 9 pages, 6 figures. Figures embedded in text. Typos corrected in text and references. Published in Physics of Plasmas. Abstract can be found at:http://link.aip.org/link/?php/12/02230

Høstfisk - utvikling av innlandsfiske 2007-2010

Prosjekt Høstfisk ble etablert våren 2007. Prosjektet fokuserer på to av de tre verdikjedene (næringsfiskeri og fisketurisme) som Landbruks- og Matdepartementets (LMD) handlingsplan fra 2006 påpeker potensialer i. Dette er første delrapport fra NIVAs undersøkelser, og er en statusbeskrivelse av bestandssituasjonen for sik i 2007 før iverksetting av tiltak. Rapporten oppsummerer også tidligere undersøkelser som har relevans for dette arbeidet. Siken i Engeren og Randsfjorden var i 2007 preget av forgubbing. Parasitteringsgraden av grovhaket gjeddemark i kjøttet var så høy i begge innsjøene at fisken ikke kan omsettes til menneskelig konsum. Utfisking av gammel sik anbefales med garn og storruse i begge innsjøene.Landbruks- og Matdepartemente

Beta lives - some statistical perspectives on the capital asset pricing model

This note summarizes some technical issues relevant to the use of the idea of excess return in empirical modelling. We cover the case where the aim is to construct a measure of expected return on an asset and a model of the CAPM type is used. We review some of the problems and show examples where the basic CAPM may be used to develop other results which relate the expected returns on assets both to the expected return on the market and other factors

HPV prevalence and concordance in the cervix and oral cavity of pregnant women.

OBJECTIVES: This investigation examined human papillomavirus (HPV) in pregnant women in order to characterize viral prevalence, types and concordance between infection in the cervix and in the oral cavity. METHODS: A total of 577 pregnant women seeking routine obstetric care were evaluated for HPV infection in their cervix during gestation and immediately before delivery, and in the oral cavity during gestation. Male partners present during the gestational clinic visit also provided a specimen from their oral cavity. HPV assessment was performed by PCR, dot blot hybridization and DNA sequencing. A sexual and health questionnaire was completed by the pregnant women. RESULTS: HPV prevalence in women was 29% in the cervix and 2.4% in the oral cavity. Among those with both gestational and delivery specimens, 35% were infected at least once and 20% had infection at both intervals. At delivery, 68% of infected women had an oncogenic HPV type in the cervix. There was no type-specific HPV concordance between the two cervical specimens, nor cervical and oral results in women, nor with cervical and oral findings between partners. CONCLUSION: The lack of association in HPV positivity and types between the cervix and oral cavity in these women suggests that self-inoculation is uncommon. This source of infection does not appear to be from oral contact with a current male partner, since there also was no concordance between partners. These results suggest either other modes of HPV transmission or differences in susceptibility to HPV infection or its clearance in the oral cavity and genital mucosa

Two-stage dissipation in a superconducting microbridge: Experiment and modeling

Using fluorescent microthermal imaging we have investigated the origin of "two-step" behavior in I-V curves for a current-carrying YBa_2Cu_3O_x superconducting bridge. High resolution temperature maps reveal that as the applied current increases the first step in the voltage corresponds to local dissipation (hot spot), whereas the second step is associated with onset of global dissipation throughout the entire bridge. A quantitative explanation of the experimental results is provided by a simple model for an inhomogeneous superconductor, assuming that the hot spot nucleates at a location with slightly depressed superconducting properties.Comment: 4 pages, 4 figure

Determining the minimum energy requirement of an LNG process: New insights into the impact of the vapour liquid equilibrium

The paper provides a detailed first principles analysis of a process of liquefaction of natural gas in which the refrigeration compressors are driven by electric motors. The aim is to determine and understand the impact of the operation of the refrigeration cycles on the power consumption of the process. This study gives a detailed insight into the relationship between the discharge pressure of the compressors and the thermodynamic performance of the refrigeration cycles. By doing this, the findings of this research highlight the importance of the vapour liquid equilibrium. The results show that, for a given production rate, there is a minimum in the power consumption when the discharge pressures are close to the refrigerant saturation points. The paper provides a discussion and analysis of the advantages and disadvantages of operating at such points

Conduction band offsets in CdZnSSe/ZnSSe single quantum wells measured by deep level transient spectroscopy

Conduction‐band offsets in wide‐band‐gap CdZnSSe/ZnSSe single quantum well structures have been characterized by deep level transient spectroscopy (DLTS) measurements. 50 Å thick Cd0.3Zn0.7S0.06Se0.94 single quantum wells with ZnS0.06Se0.94 barriers were grown by molecular beam epitaxy on GaAs substrates. A thermal emission energy from the quaternary wells of 179±10 meV was measured. This corresponds to a conduction‐band offset energy of ∼251±20 meV. © 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71191/2/APPLAB-68-25-3591-1.pd