3,901 research outputs found

    A Technique for Physiologically Age-Grading Female Stable Flies, Stomoxys calcitrans (L.)

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    A method of dissection followed by staining was initiated to allow physiological age- grading based on ovarian development in order to more completely describe the physiological development of adult female stable flies [Stomoxys calcitrans (L. )]. The gonotrophic developmental continuum from a non-differentiated cell in teneral females to mature eggs at the time of oviposition was first arbitrarily divided into six stages by using distinct landmarks within the developing oocyte . Then, nulliparous, uniparous, and biparous+ females were differentiated on the basis of the presence or absence of stained follicular relics in the ovariole sheaths. The combination of the two techniques made it possible to assign dissected adult female stable flies to one of 12 age-classes

    A Technique for Physiologically Age-Grading Female Stable Flies, Stomoxys calcitrans (L.)

    Get PDF
    A method of dissection followed by staining was initiated to allow physiological age- grading based on ovarian development in order to more completely describe the physiological development of adult female stable flies [Stomoxys calcitrans (L. )]. The gonotrophic developmental continuum from a non-differentiated cell in teneral females to mature eggs at the time of oviposition was first arbitrarily divided into six stages by using distinct landmarks within the developing oocyte . Then, nulliparous, uniparous, and biparous+ females were differentiated on the basis of the presence or absence of stained follicular relics in the ovariole sheaths. The combination of the two techniques made it possible to assign dissected adult female stable flies to one of 12 age-classes

    Ring baffle pressure distribution and slosh damping in large cylindrical tanks

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    An investigation was conducted to determine the pressure loads and damping associated with rigid ring baffles in relatively large cylindrical tanks. The radial and circumferential pressure distribution, as well as the damping, was measured on a ring baffle subjected to fundamental antisymmetric slosh in a 284-cm-diameter rigid tank. Experimental and analytical data are presented as a function of slosh velocity or amplitude, baffle spacing, and baffle locations both above and below the liquid surface. Results suggest that pressure distributions and damping values can be determined from available theories for the design of single and multiple baffle configurations

    Evaluation of minor pathogen intramammary infection, susceptibility parameters, and somatic cell counts on the development of new intramammary infections with major mastitis pathogens

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    Major mastitis pathogens such as Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, and coliforms are usually considered more virulent and damaging to the udder than minor mastitis pathogens such as Corynebacterium spp. and coagulase-negative staphylococci (CNS). The current literature comprises several studies (n=38) detailing analyses with conflicting results as to whether intramammary infections (IMI) with the minor pathogens decrease, increase, or have no effect on the risk of a quarter acquiring a new IMI (NIMI) with a major pathogen. The Canadian Bovine Mastitis Research Network has a large mastitis database derived from a 2-yr data collection on a national cohort of dairy farms, and data from this initiative were used to further investigate the effect of IMI with minor pathogens on the acquisition of new major pathogen infections (defined as a culture-positive quarter sample in a quarter that had been free of that major pathogen in previous samples in the sampling period). Longitudinal milk samplings of clinically normal udders taken over several 6-wk periods as well as samples from cows pre-dry-off and postcalving were used to this end (n=80,397 quarter milk samples). The effects of CNS and Corynebacterium spp. on the major mastitis pathogens Staph. aureus, Strep. uberis, Strep. dysgalactiae, and coliform bacteria (Escherichia coli and Klebsiella spp.) were investigated using risk ratio analyses and multilevel logistic regression models. Quarter-, cow- and herd-level susceptibility parameters were also evaluated and were able to account for the increased susceptibility that exists within herds, cows and quarters, removing it from estimates for the effects of the minor pathogens. Increased quarter-level susceptibility was associated with increased risk of major pathogen NIMI for all pathogens except the coliforms. Increased somatic cell count was consistently associated with elevated risk of new major pathogen infections, but this was assumed to be a result of low sensitivity of bacteriology to diagnose major pathogen NIMI expediently and accurately. The presence of CNS in the sample 2 samplings before the occurrence of a NIMI increased the odds of experiencing a Staph. aureus NIMI 2.0 times, making the presence of CNS a risk factor for acquiring a Staph. aureus NIMI. Even with this extensive data set, power was insufficient to make a definitive statement about the effect of minor pathogen IMI on the acquisition of major pathogen NIMI. Definitively answering questions of this nature are likely to require an extremely large data set dedicated particularly to minor pathogen presence and NIMI with major pathogens.Source type: Electronic(1

    A storage and access architecture for efficient query processing in spatial database systems

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    Due to the high complexity of objects and queries and also due to extremely large data volumes, geographic database systems impose stringent requirements on their storage and access architecture with respect to efficient query processing. Performance improving concepts such as spatial storage and access structures, approximations, object decompositions and multi-phase query processing have been suggested and analyzed as single building blocks. In this paper, we describe a storage and access architecture which is composed from the above building blocks in a modular fashion. Additionally, we incorporate into our architecture a new ingredient, the scene organization, for efficiently supporting set-oriented access of large-area region queries. An experimental performance comparison demonstrates that the concept of scene organization leads to considerable performance improvements for large-area region queries by a factor of up to 150

    Triaxiality and the determination of the cubic shape parameter K3 from five observables

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    The absolute and the relative quadrupole shape invariants q3 and K3 provide a model independent measure of triaxiality for beta-rigid nuclei. We will show that one can obtain q3 and K3 from a small number of observables. The approximations which are made will be shown to hold within a few percent both in the rigid triaxial rotor model and the interacting boson model. The shape parameter K3 is given for an exemplary set of nuclei and is translated into effective values of the geometrical deformation parameters beta and gamma.Comment: 16 pages, 4 figure
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