1,761 research outputs found
Pasture Utilization at Islands in Northern Norway
The Norwegian sheep industry is based on utilization of âfreeâ rangeland pasture resources. Use of mountain pastures is dominating, with about two million sheep grazing these pastures during summer. Regional challenges related to e.g., loss of sheep to large carnivores make farmers think differently. The Norwegian coastline is among the longest globally and is scattered with islets and islands. Alone along the coast of Nordland county, it is estimated more than 14,000 islands. Use of islands for summer pasture is an alternative but there is a limited knowledge about such a management system. In this study, we examined lambsâ average daily gain on island pastures at the coast of Norway. In total 230 lambs on three islands (SandvĂŚr, Sjonøya, and Buøya), with varying pasture quality and stocking rate, for 3 years (2012, 2013, and 2014). At SandvĂŚr as much as 92% of the island was characterized as high nutritional value while at Sjonøya and Buøya only 15%, was characterized high nutritional value. We found an average daily lamb growth rate of 0.320 kg dâ1. Lambs on SandvĂŚr had a higher daily gain (P \u3c 0.05) than those on Sjonøya and Buøya, and lambsâ average daily gain was significantly lower (P \u3c 0.05) in 2013 compared to 2012 and 2014. We conclude that with a dynamic and adaptive management strategy there is a potential to utilize islands for sheep grazing during summer
SPECIFICATION AND PROCUREMENT OF CP-5 FUEL TUBES.
Contains the specifications of CP-5 fuel tubes
On the Saturation of Astrophysical Dynamos: Numerical Experiments with the No-cosines flow
In the context of astrophysical dynamos we illustrate that the no-cosines
flow, with zero mean helicity, can drive fast dynamo action and study the
dynamo's mode of operation during both the linear and non-linear saturation
regime: It turns out that in addition to a high growth rate in the linear
regime, the dynamo saturates at a level significantly higher than normal
turbulent dynamos, namely at exact equipartition when the magnetic Prandtl
number is on the order of unity. Visualization of the magnetic and velocity
fields at saturation will help us to understand some of the aspects of the
non-linear dynamo problem.Comment: 8 pages, 5 figures, submitted to the proceedings of "Space Climate 1"
to be peer-reviewed to Solar Physic
DNA adducts in human urinary bladder and other tissues.
Tobacco smoking is associated with an increased risk of cancer in a number of organs, including bladder and lung. Tobacco smoke contains at least 50 known chemical carcinogens that exert their biological effects through their covalent binding to cellular DNA. Examining human DNA for the presence of altered nucleotides is a means of monitoring exposure to genotoxic chemicals. DNA isolated from 73 human bladder biopsies has been analyzed by 32P-postlabeling for the presence of aromatic/hydrophobic adducts. Butanol extraction of DNA digests resulted in up to a 3-fold greater recovery of adducts than nuclease P1 digestion. Among 16 nonsmokers, adduct levels were in the range 3.2-20.8/10(8) nucleotides (mean 9.7). Eight ex-smokers had values in the range 2.6-12.3 (mean 7.1). Thirteen smokers had adduct levels between 1.3 and 26.7 adducts/10(8) nucleotides (mean 9.5, not different from nonsmokers). Six cigar smokers had higher levels of adducts (mean 12.1, range 7.3-15.0), but pipe smokers did not (five samples, mean 8.6, range 2.9-12.7). A further 8 samples from nonsmokers and 17 from smokers were examined in more detail. Although most of the DNA binding appears not to be smoking related, the levels of one adduct were found to be on average 2-fold higher in smokers (p < 0.005, one-tailed t test). Studies on tissues of the respiratory tract demonstrate a correlation between DNA adduct levels and exposure to tobacco smoke. Evidence to date on the influence of smoking on adducts in peripheral blood cells is equivocal; some studies demonstrate a significant effect, whereas others do not.(ABSTRACT TRUNCATED AT 250 WORDS
Magnetic helicity fluxes in an alpha-squared dynamo embedded in a halo
We present the results of simulations of forced turbulence in a slab where
the mean kinetic helicity has a maximum near the mid-plane, generating
gradients of magnetic helicity of both large and small-scale fields. We also
study systems that have poorly conducting buffer zones away from the midplane
in order to assess the effects of boundaries. The dynamical alpha quenching
phenomenology requires that the magnetic helicity in the small-scale fields
approaches a nearly static, gauge independent state. To stress-test this steady
state condition we choose a system with a uniform sign of kinetic helicity, so
that the total magnetic helicity can reach a steady state value only through
fluxes through the boundary, which are themselves suppressed by the velocity
boundary conditions. Even with such a set up, the small-scale magnetic helicity
is found to reach a steady state. In agreement with earlier work, the magnetic
helicity fluxes of small-scale fields are found to be turbulently diffusive. By
comparing results with and without halos, we show that artificial constraints
on magnetic helicity at the boundary do not have a significant impact on the
evolution of the magnetic helicity, except that "softer" (halo) boundary
conditions give a lower energy of the saturated mean magnetic field.Comment: 12 pages, 5 figures, submitted to GAF
The alpha effect with imposed and dynamo-generated magnetic fields
Estimates for the nonlinear alpha effect in helical turbulence with an
applied magnetic field are presented using two different approaches: the
imposed-field method where the electromotive force owing to the applied field
is used, and the test-field method where separate evolution equations are
solved for a set of different test fields. Both approaches agree for stronger
fields, but there are apparent discrepancies for weaker fields that can be
explained by the influence of dynamo-generated magnetic fields on the scale of
the domain that are referred to as meso-scale magnetic fields. Examples are
discussed where these meso-scale fields can lead to both drastically
overestimated and underestimated values of alpha compared with the kinematic
case. It is demonstrated that the kinematic value can be recovered by resetting
the fluctuating magnetic field to zero in regular time intervals. It is
concluded that this is the preferred technique both for the imposed-field and
the test-field methods.Comment: 10 pages, 8 figures, published versio
Conduction band offsets in CdZnSSe/ZnSSe single quantum wells measured by deep level transient spectroscopy
Conductionâband offsets in wideâbandâgap CdZnSSe/ZnSSe single quantum well structures have been characterized by deep level transient spectroscopy (DLTS) measurements. 50 Ă
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 179Âą10 meV was measured. This corresponds to a conductionâband offset energy of âź251Âą20 meV. Š 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71191/2/APPLAB-68-25-3591-1.pd
Current status of turbulent dynamo theory: From large-scale to small-scale dynamos
Several recent advances in turbulent dynamo theory are reviewed. High
resolution simulations of small-scale and large-scale dynamo action in periodic
domains are compared with each other and contrasted with similar results at low
magnetic Prandtl numbers. It is argued that all the different cases show
similarities at intermediate length scales. On the other hand, in the presence
of helicity of the turbulence, power develops on large scales, which is not
present in non-helical small-scale turbulent dynamos. At small length scales,
differences occur in connection with the dissipation cutoff scales associated
with the respective value of the magnetic Prandtl number. These differences are
found to be independent of whether or not there is large-scale dynamo action.
However, large-scale dynamos in homogeneous systems are shown to suffer from
resistive slow-down even at intermediate length scales. The results from
simulations are connected to mean field theory and its applications. Recent
work on helicity fluxes to alleviate large-scale dynamo quenching, shear
dynamos, nonlocal effects and magnetic structures from strong density
stratification are highlighted. Several insights which arise from analytic
considerations of small-scale dynamos are discussed.Comment: 36 pages, 11 figures, Spa. Sci. Rev., submitted to the special issue
"Magnetism in the Universe" (ed. A. Balogh
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