Do Two Temperature Debris Disks Have Multiple Belts?

We present a study of debris disks whose spectra are well modelled by dust emission at two different temperatures. These disks are typically assumed to be a sign of multiple belts, which in only a few cases have been confirmed via high resolution observations. We first compile a sample of two-temperature disks to derive their properties, summarised by the ratios of the warm and cool component temperatures and fractional luminosities. The ratio of warm to cool temperatures is constant in the range 2-4, and the temperatures of both warm and cool components increases with stellar mass. We then explore whether this emission can arise from dust in a single narrow belt, with the range of temperatures arising from the size variation of grain temperatures. This model can produce two-temperature spectra for Sun-like stars, but is not supported where it can be tested by observed disk sizes and far-IR/mm spectral slopes. Therefore, while some two-temperature disks arise from single belts, it is probable that most have multiple spatial components. These disks are plausibly similar to the outer Solar System's configuration of Asteroid and Edgeworth-Kuiper belts separated by giant planets. Alternatively, the inner component could arise from inward scattering of material from the outer belt, again due to intervening planets. In either case, we suggest that the ratio of warm/cool component temperatures is indicative of the scale of outer planetary systems, which typically span a factor of about ten in radius.Comment: accepted to MNRA

Deduced Primary Structure of the β Subunit of Brain Type II Ca2+/calmodulin-dependent Protein Kinase Determined by Molecular Cloning

cDNA clones coding for the β subunit of rat brain type II Ca2+/calmodulin-dependent protein kinase were isolated and sequenced. The clones, including one containing the entire coding region, hybridize at high stringency to a single band of poly(A)+ RNA of length 4.8 kilobases. The subunit coded for by the clones was identified by in vitro transcription of the cDNA followed by translation of the resulting RNA. The DNA sequence of the clones contains a single long open reading frame (1626 nucleotides) coding for a protein of 542 amino acids with a molecular weight of 60,333, the amino-terminal half of which is homologous to several other protein kinases. Potential ATP- and calmodulin-binding domains were identified. Two independent clones contain an identical 45-nucleotide deletion, relative to the clones described above, resulting in a shorter open reading frame coding for a protein of molecular weight 58,000. This suggests that the minor, 58-kDa β' subunit of the type II Ca2+/calmodulin-dependent kinase may be synthesized on a separate message

Purification and characterization of a calmodulin-dependent protein kinase that is highly concentrated in brain

A calcium and calmodulin-dependent protein kinase has been purified from rat brain. It was monitored during the purification by its ability to phosphorylate the synaptic vesicle-associated protein, synapsin I. A 300-fold purification was sufficient to produce kinase that is 90-95% pure as determined by scans of stained sodium dodecyl sulfate-polyacrylamide gels and has a specific activity of 2.9 mumol of 32P transferred per min/mg of protein. Thus, the kinase is a relatively abundant brain enzyme, perhaps comprising as much as 0.3% of the total brain protein. The Stokes radius (95 A) and sedimentation coefficient (16.4 S) of the kinase indicate a holoenzyme molecular weight of approximately 650,000. The holoenzyme is composed of three subunits as judged by their co-migration with kinase activity during the purification steps and co-precipitation with kinase activity by a specific anti-kinase monoclonal antibody. The three subunits have molecular weights of 50,000, 58,000, and 60,000, and have been termed alpha, beta', and beta, respectively. The alpha- and beta-subunits are distinct peptides, however, beta' may have been generated from beta by proteolysis. All three of these subunits bind calmodulin in the presence of calcium and are autophosphorylated under conditions in which the kinase is active. The subunits are present in a ratio of about 3 alpha-subunits to 1 beta/beta'-subunit. We therefore postulate that the 650,000-Da holoenzyme consists of approximately 9 alpha-subunits and 3 beta/beta'-subunits. The abundance of this calmodulin-dependent protein kinase indicates that its activation is likely to be an important biochemical response to increases in calcium ion concentration in neuronal tissue

Animal Behavior: Impacts on Grazing

I am not an expert on this subject and give all credit for my limited understanding of this subject to Dr. Fred Provenza, Utah State University; Katy Voth, Livestock for Landscapes, LLC; Jim Gerrish and others. I have tried to put into practice, both personally and with other producers, many of these principles to aid in improved grazing management. This presentation will address only 2 aspects of animal behavior; 1) How animal behavior impacts grazing distribution and forage utilization over the landscape, and 2) How animal behavior affects diet selection

Perennial Warm Season Grasses in Grazing Programs

Many warm season perennial grasses were once an important part of the plant community in much of the Midwest. Conversion to cropping systems, overgrazing, lack of regular fire and increased competition from cool-season grasses and legumes have caused many of these grasses to disappear from much of the region. However, warm season grasses can compliment cool-season pastures if managed properly. Midwest stockmen are rediscovering the usefulness of warm season grasses in their overall forage program. Adding these grasses to forage systems has resulted in increased gains and improved livestock performance during the summer months when cool-season grasses are at their low point of growth and quality. Warm season grasses are highly palatable to livestock prior to heading and can produce beef gains of over 2 pounds per day during the summer season. Graziers should take advantage of the inherent differences in the seasonal growth cycles of various forages to supply desirable forage to livestock throughout the grazing season

Mob Grazing, High Density Grazing, Management-Intensive Grazing: What\u27s the Difference?

Before we can answer that question we need to review some basic fundamentals of successful grazing management. Four goals of any sustainable grazing management strategy should be: 1) Meet the nutritional needs of livestock from standing pasture as many days as possible; 2) Optimize pasture yield, quality and persistence; 3) Maintain or enhance the natural resource base; 4) Integrate the appropriate technology and knowledge into a practical and profitable system that fits your available resources and meets your objectives. We will use these goals to compare and contrast these 2 grazing management techniques. Both techniques should be considered tools in the grazier’s toolbox. No one tool is perfect for every job. Each has a place and can be successful if monitored and managed properly