Magnetometeorology: Relationships between the weather and earth's magnetic field

A comparison of meteorological pressures and the strength of earth's magnetic field shows that the magnetic field exerts a controlling influence on the average pressure in the troposphere at high latitudes. The possibility of long-term changes in the goemagnetic field affecting the climate is discussed

Winter wheat: A model for the simulation of growth and yield in winter wheat

The basic ideas and constructs for a general physical/physiological process level winter wheat simulation model are documented. It is a materials balance model which calculates daily increments of photosynthate production and respiratory losses in the crop canopy. The partitioning of the resulting dry matter to the active growing tissues in the plant each day, transpiration and the uptake of nitrogen from the soil profile are simulated. It incorporates the RHIZOS model which simulates, in two dimensions, the movement of water, roots, and soluble nutrients through the soil profile. It records the time of initiation of each of the plant organs. These phenological events are calculated from temperature functions with delays resulting from physiological stress. Stress is defined mathematically as an imbalance in the metabolite supply; demand ratio. Physiological stress is also the basis for the calculation of rates of tiller and floret abortion. Thus, tillering and head differentiation are modeled as the resulants of the two processes, morphogenesis and abortion, which may be occurring simulaneously

Thermal and Non-thermal Plasmas in the Galaxy Cluster 3C 129

We describe new Chandra spectroscopy data of the cluster which harbors the prototypical "head tail" radio galaxy 3C 129 and the weaker radio galaxy 3C 129.1. We combined the Chandra data with Very Large Array (VLA) radio data taken at 0.33, 5, and 8 GHz (archival data) and 1.4 GHz (new data). We also obtained new HI observations at the Dominion Radio Astrophysical Observatory (DRAO) to measure the neutral Hydrogen column density in the direction of the cluster with arcminute angular resolution. The Chandra observation reveals extended X-ray emission from the radio galaxy 3C 129.1 with a total luminosity of 1.5E+41 erg/s. The X-ray excess is resolved into an extended central source of ~2 arcsec (1 kpc) diameter and several point sources with an individual luminosity up to 2.1E+40 erg/s. In the case of the radio galaxy 3C 129, the Chandra observation shows, in addition to core and jet X-ray emission reported in an earlier paper, some evidence for extended, diffuse X-ray emission from a region east of the radio core. The 12 arcsec x 36 arcsec (6 kpc x 17 kpc) region lies "in front" of the radio core, in the same direction into which the radio galaxy is moving. We use the radio and X-ray data to study in detail the pressure balance between the non-thermal radio plasma and the thermal Intra Cluster Medium (ICM) along the tail of 3C 129 which extends over 15 arcmin (427 kpc). Depending on the assumed lower energy cutoff of the electron energy spectrum, the minimum pressure of the radio plasma lies a factor of between 10 and 40 below the ICM pressure for a large part of the tail. We discuss several possibilities to explain the apparent pressure mismatch.Comment: Accepted for publication in MNRAS. Refereed manuscript. 14 pages, 8 figures, additional panel of Fig. 3 shows asymmetric ICM distributio

Good Pond Fishing is No Accident

There are approximately 100,000 ponds (also called stock dams) in South Dakota; 48,000 contain fish. Most ponds are privately owned and are on ranches in western and central South Dakota. Ponds must be managed if they are to provide quality angling. And if properly managed, they can provide memorable fishing year after year. A common misconception is that a pond can have it all, that it can be stocked with any and all fish species and that the fishing will be good for all species. It is more likely that fishing may not be good for any species. In reality, you must decide what you want and choose that management option that best fits your needs. We present the following key and discussion to help you decide the best pond management strategy for you. Start with Number 1 in the key and follow the directions after the answer that best fits you and your pond

Environmental characteristics of black crappie (\u3ci\u3ePomoxis nigromaculatus\u3c/i\u3e) nesting sites in two South Dakota waters

A biotelemetry study was undertaken during spring 1995 to identify black crappie (Pomoxis nigromaculatus) nesting sites in two South Dakota water bodies. Individually coded ultrasonic transmitters were implanted into the body cavity of 15 adult male black crappie in each water body prior to spawning. Available habitat characteristics were recorded at 75 randomly selected sites within each water body, and habitat characteristics at nesting sites were recorded for each male black crappie believed to be nesting. Of the habitat characteristics analyzed, only substrate firmness did not differ (P=0.79) between water bodies. In Richmond Lake, black crappie selected nesting sites with live cattails (Typha spp.) that were protected from prevailing south winds. In Brant Lake, black crappie selected nest sites with vegetation (usually woody debris) and silty substrate that had warmer water and were protected from wind and waves. It appeared that black crappie nested in the most protected areas available

Gas Purity effect on GEM Performance in He and Ne at Low Temperatures

The performance of Gas Electron Multipliers (GEMs) in gaseous He, Ne, He+H2 and Ne+H2 was studied at temperatures in the range of 3-293 K. This paper reports on previously published measurements and additional studies on the effects of the purity of the gases in which the GEM performance is evaluated. In He, at temperatures between 77 and 293 K, triple-GEM structures operate at rather high gains, exceeding 1000. There is an indication that this high gain is achieved through the Penning effect as a result of impurities in the gas. At lower temperatures the gain-voltage characteristics are significantly modified probably due to the freeze-out of these impurities. Double-GEM and single-GEM structures can operate down to 3 K at gains reaching only several tens at a gas density of about 0.5 g/l; at higher densities the maximum gain drops further. In Ne, the maximum gain also drops at cryogenic temperatures. The gain drop in Ne at low temperatures can be re-established in Penning mixtures of Ne+H2: very high gains, exceeding 104, have been obtained in these mixtures at 30-77 K, at a density of 9.2 g/l which corresponds to saturated Ne vapor density at 27 K. The addition of small amounts of H2 in He also re-establishes large GEM gains above 30 K but no gain was observed in He+H2 at 4 K and a density of 1.7 g/l (corresponding to roughly one-tenth of the saturated vapor density). These studies are, in part, being pursued in the development of two-phase He and Ne detectors for solar neutrino detection.Comment: 4 pages, 7 figure

Channel Catfish Diets Include Substantial Vegetation in a Missouri River Reservoir

Channel catfish (Ictalurus punctatus) are native to Lake Sharpe, a Missouri River mainstem reservoir, and are common in angler catches. Channel catfish growth has declined since the formation of the reservoir in 1963. Mean lengths at time of capture for channel catfish ages 9, 10, II, and 12 have decreased by 69, 55, 115, and 21S mm, respectively, since impoundment. The objective of this study was to document monthly food habits of channel catfish throughout the growing season (May-August) in Lake Sharpe to assess potential effects of diet on growth. Although channel catfish consumed both macro invertebrates and fishes as expected, they also consumed large quantities of submergent aquatic vegetation. Consumed vegetation contributed 3S-73% of the diet by weight over 2 channel catfish length groups «2S0 mm and ~2S0 mm total length) during the 4 months sampled. Consumption of substantial amounts of vegetation should be considered a suboptimal diet for channel catfish growth. Consequently, diets of channel catfish in Lake Sharpe could be a factor contributing to the observed slow growth of older catfish in this population

Temperature, Hatch Date, and Prey Availability Influence Age-0 Yellow Perch Growth and Survival

Throughout their range, Yellow Perch Perca flavescens are an important ecological and economic component of many fisheries, but they often exhibit highly variable recruitment. Much research effort has been devoted to better understanding the mechanisms responsible for these erratic recruitment patterns, yet few studies have examined this process at the detail necessary to reveal complex interactions that may exist across multiple early life stages. Our current understanding of the early life recruitment patterns of Yellow Perch suggests a strong abiotic component. Using existing information, we developed three working hypotheses to examine Yellow Perch recruitment at two larval stages (5–14 and 15–24 d old) and to further identify the overarching mechanisms (abiotic versus biotic) related to Yellow Perch recruitment in 332-ha Pelican Lake, Nebraska, during 2004–2012. Larval Yellow Perch growth and mortality were largely regulated by hatching date, temperature, and zooplankton availability. The growth of young larval Yellow Perch (5–14 d old) was positively related to temperature and hatch date; that of old larval perch (15–24 d old) was positively related to water temperature and postlarval age-0 (≤25 mm TL) Yellow Perch density but negatively related to the available preferred zooplankton biomass. Mortality was inversely related to total zooplankton biomass and water temperature. Our results describe a model with two potential Yellow Perch recruitment bottlenecks, one immediately posthatch that is regulated by hatch date and temperature and another during the older larval stage that is regulated by temperature and zooplankton

Temperature, Hatch Date, and Prey Availability Influence Age-0 Yellow Perch Growth and Survival

Throughout their range, Yellow Perch Perca flavescens are an important ecological and economic component of many fisheries, but they often exhibit highly variable recruitment. Much research effort has been devoted to better understanding the mechanisms responsible for these erratic recruitment patterns, yet few studies have examined this process at the detail necessary to reveal complex interactions that may exist across multiple early life stages. Our current understanding of the early life recruitment patterns of Yellow Perch suggests a strong abiotic component. Using existing information, we developed three working hypotheses to examine Yellow Perch recruitment at two larval stages (5–14 and 15–24 d old) and to further identify the overarching mechanisms (abiotic versus biotic) related to Yellow Perch recruitment in 332-ha Pelican Lake, Nebraska, during 2004–2012. Larval Yellow Perch growth and mortality were largely regulated by hatching date, temperature, and zooplankton availability. The growth of young larval Yellow Perch (5–14 d old) was positively related to temperature and hatch date; that of old larval perch (15–24 d old) was positively related to water temperature and postlarval age-0 (≤25 mm TL) Yellow Perch density but negatively related to the available preferred zooplankton biomass. Mortality was inversely related to total zooplankton biomass and water temperature. Our results describe a model with two potential Yellow Perch recruitment bottlenecks, one immediately posthatch that is regulated by hatch date and temperature and another during the older larval stage that is regulated by temperature and zooplankton