3,983 research outputs found

    Comparing the effects of monensin and sodium butyrate on coccidia in post-weaned heifers

    Get PDF
    The emergence of antibiotic resistances has raised concerns in society about the widespread use of antibiotics, such as monensin, as growth enhancers in agriculture. Pressure to find alternatives has increased since the European Union banned the use of ionophorous antibiotics. Butyrate supplementation has been found to enhance growth in pre-weaned calves and it has been recently suggested to enhance growth in post-weaned heifers. In a recent study by Rice in 2017, there was a quadratic (P=0.03) response for coccidia counts as sodium butyrate was increased, with the lowest counts being at the intermediate doses. This suggested that butyrate has the potential to decrease coccidian in post-weaned heifers. Monensin is also used as a coccidiostat. While the objective of the study as a whole was to determine if sodium butyrate can replace monensin in the prevention of coccidiosis and in enhancing growth and feed efficiency, this report focuses only on the prevention of coccidiosis. At this time, only six of the forty Holstein heifers entered the study. The design was a 2 X 2 factorial arrangement of treatments in a randomized complete block design. Heifers were randomly assigned to 1 of 4 treatments: (1) carrier (control; C); (2) 0.75 g SB/kg of body weight + carrier (SB); (3) 1.0 mg M/kg of body weight + carrier (M); (4) (0.75 g SB/kg of body weight and 1.0 mg M/kg of body weight + carrier (SB/M). Heifers entered the study and were trained to Calan doors from week 12 to 13 age of life. Treatment began on week 14 of life and continued for 12 weeks. Fecal samples were taken from each calf weekly beginning in the covariate period for determination of coccidia. (Measurements were also taken to evaluate the growth of post weaned calves and apparent total tract nutrient digestibility). Oocyte counts were determined through the modified Wisconsin sugar floatation method. Due to the small sample size a statistical analysis was unable to be completed. However, the preliminary data suggested a negative trend in coccidian oocyte counts 2 as treatment progressed. This indicates that both sodium butyrate and monensin have the ability to decrease the shedding of coccidian oocytes, though the statistical significance is not known at this time

    Low phase-shift amplifier

    Get PDF
    Single-stage MOSFET amplifier is described which is identical to standard neutralized amplifier except that neutralization provided by broadband transformer is applied to AGC gate instead of signal gate. Neutralization of drain-to-control gate capacity minimizes the phase change induced by variation in AGC

    High-Temperature, Low-Cycle Fatigue Behavior of Tantalum

    Get PDF
    High temperature, low cycle fatigue tests of tantalum in inert argon atmospher

    Frequency and timing system for the consolidated DSN and STDN tracking network

    Get PDF
    The consolidation on the existing Deep Space Network (DSN) and colocated Goddard Spaceflight Tracking and Data Network (STDN) stations into a multiple antenna array is discussed. Each site includes a signal processing center (SPC) centered in an array of four or five antennas each located within approximately 300 to 800 meters of the SPC. A central frequency and timing system (FTS) located in the SPC contains reference frequency, timing and time code generation, and distribution equipment for both the SPC and each antenna with its associated front end antenna control building. The reference frequency distribution and clock equipment are driven by a hydrogen maser as the prime frequency standard with cesium beam frequency standard as the secondary

    Fluctuations and scaling in creep deformation

    Get PDF
    The spatial fluctuations of deformation are studied in creep in the Andrade's power-law and the logarithmic phases, using paper samples. Measurements by the Digital Image Correlation technique show that the relative strength of the strain rate fluctuations increases with time, in both creep regimes. In the Andrade creep phase characterized by a power law decay of the strain rate ϵttθ\epsilon_t \sim t^{-\theta}, with θ0.7\theta \approx 0.7, the fluctuations obey Δϵttγ\Delta \epsilon_t \sim t^{-\gamma}, with γ0.5\gamma \approx 0.5. The local deformation follows a data collapse appropriate for an absorbing state/depinning transition. Similar behavior is found in a crystal plasticity model, with a jamming or yielding phase transition

    Predicting Noise From Aircraft Turbine-Engine Combustors

    Get PDF
    COMBUSTOR and CNOISE are computer codes that predict far-field noise that originates in the combustors of modern aircraft turbine engines -- especially modern, low-gaseous-emission engines, the combustors of which sometimes generate several decibels more noise than do the combustors of older turbine engines. COMBUSTOR implements an empirical model of combustor noise derived from correlations between engine-noise data and operational and geometric parameters, and was developed from databases of measurements of acoustic emissions of engines. CNOISE implements an analytical and computational model of the propagation of combustor temperature fluctuations (hot spots) through downstream turbine stages. Such hot spots are known to give rise to far-field noise. CNOISE is expected to be helpful in determining why low-emission combustors are sometimes noisier than older ones, to provide guidance for refining the empirical correlation model embodied in the COMBUSTOR code, and to provide insight on how to vary downstream turbinestage geometry to reduce the contribution of hot spots to far-field noise

    Properties of Exotic Matter for Heavy Ion Searches

    Full text link
    We examine the properties of both forms of strange matter, small lumps of strange quark matter (strangelets) and of strange hadronic matter (Metastable Exotic Multihypernuclear Objects: MEMOs) and their relevance for present and future heavy ion searches. The strong and weak decays are discussed separately to distinguish between long-lived and short-lived candidates where the former ones are detectable in present heavy ion experiments while the latter ones in future heavy ion experiments, respectively. We find some long-lived strangelet candidates which are highly negatively charged with a mass to charge ratio like a anti deuteron (M/Z=-2) but masses of A=10 to 16. We predict also many short-lived candidates, both in quark and in hadronic form, which can be highly charged. Purely hyperonic nuclei are bound and have a negative charge while carrying a positive baryon number. We demonstrate also that multiply charmed exotics (charmlets) might be bound and can be produced at future heavy ion colliders.Comment: 10 pages, 4 figures, uses IOP style and epsf.sty, to be published in Journal of Physics, Proceedings of the International Symposium on Strangeness in Quark Matter 1997, April 14-18, Thera (Santorini), Hellas. Corrected typos, added comment about bag constant

    Underground railroads: citizen entitlements and unauthorized mobility in the antebellum period and today

    Get PDF
    In recent years, some scholars and prominent political figures have advocated the deepening of North American integration on roughly the European Union model, including the creation of new political institutions and the free movement of workers across borders. The construction of such a North American Union, if it included even a very thin trans-state citizenship regime, could represent the most significant expansion of individual entitlements in the region since citizenship was extended to former slaves in the United States. With such a possibility as its starting point, this article explores some striking parallels between the mass, legally prohibited movement across boundaries by fugitive slaves in the pre-Civil War period, and that by current unauthorized migrants to the United States. Both were, or are, met on their journeys by historically parallel groups of would-be helpers and hinderers. Their unauthorized movements in both periods serve as important signals of incomplete entitlements or institutional protections. Most crucially, moral arguments for extending fuller entitlements to both groups are shown here to be less distinct than may be prima facie evident, reinforcing the case for expanding and deepening the regional membership regime

    Can Doubly Strange Dibaryon Resonances be Discovered at RHIC?

    Full text link
    The baryon-baryon continuum invariant mass spectrum generated from relativistic nucleus + nucleus collision data may reveal the existence of doubly-strange dibaryons not stable against strong decay if they lie within a few MeV of threshold. Furthermore, since the dominant component of these states is a superposition of two color-octet clusters which can be produced intermediately in a color-deconfined quark-gluon plasma (QGP), an enhanced production of dibaryon resonances could be a signal of QGP formation. A total of eight, doubly-strange dibaryon states are considered for experimental search using the STAR detector (Solenoidal Tracker at RHIC) at the new Relativistic Heavy Ion Collider (RHIC). These states may decay to Lambda-Lambda and/or proton-Cascade-minus, depending on the resonance energy. STAR's large acceptance, precision tracking and vertex reconstruction capabilities, and large data volume capacity, make it an ideal instrument to use for such a search. Detector performance and analysis sensitivity are studied as a function of resonance production rate and width for one particular dibaryon which can directly strong decay to proton-Cascade-minus but not Lambda-Lambda. Results indicate that such resonances may be discovered using STAR if the resonance production rates are comparable to coalescence model predictions for dibaryon bound states.Comment: 28 pages, 5 figures, revised versio

    Dibaryons with Strangeness: their Weak Nonleptonic Decay using SU(3) Symmetry and how to find them in Relativistic Heavy-Ion Collisions

    Get PDF
    Weak SU(3) symmetry is successfully applied to the weak hadronic decay amplitudes of octet hyperons. Weak nonmesonic and mesonic decays of various dibaryons with strangeness, their dominant decay modes, and lifetimes are calculated. Production estimates for BNL's Relativistic Heavy-Ion Collider are presented employing wave function coalescence. Signals for detecting strange dibaryon states in heavy-ion collisions and revealing information about the unknown hyperon-hyperon interactions are outlined.Comment: 4 pages, 2 figures, uses RevTeX, discussion about the model of the weak decay and experimental signals extended, references update
    corecore