1,071 research outputs found
Intertemporal Substitution and the Liquidity Effect in a Sticky Price Model
The liquidity effect, defined as a decrease in nominal interest rates in response to a monetary expansion, is a major stylized fact of the business cycle. This paper seeks to understand under what conditions such an effect can be explained in a general equilibrium model with sticky prices and capital adjustment costs. The paper first confirms that, with separable preferences, a low degree of intertemporal substitution in consumption is a necessary condition for the existence of the liquidity effect. Contrary to this result, in a model with non-separable preferences and capital accumulation it takes an implausibly high degree of intertemporal substitution to produce a liquidity effect. The robustness of these results to alternative degrees of nominal rigidities, money demand properties and real rigidities is also analyzed.
Bilingual, digital, audio-visual training modules improve technical knowledge of feedlot and dairy workers
Two studies were conducted to determine the effectiveness of digital multimedia modules as training tools for animal care workers. Employees at a commercial feedlot (n = 17) and a commercial dairy (n = 10) were asked to independently complete a 10-question quiz prior to and following viewing of training modules. Module topics in the feedlot were proper handling of non-ambulatory animals and humane methods of euthanasia; modules were administered to the workers, as a group, in either English (n = 7) or Spanish (N = 10), depending on previously indicated worker preference. Modules addressing dairy cattle health practices and dairy cattle handling were presented to the dairy care workers who had a preference for learning in either English (n = 7) or Spanish (n = 3). For feedlot workers, post-test scores were improved by 28% after viewing the modules compared to pre-test scores (74% vs. 58%; P 0.30) between language, topic, and between-test variation, indicating that the modules were equally effective at information delivery to both audiences in both languages. For the dairy workers, test scores improved by 27% from pre-viewing to post-viewing (73% vs. 92%; P < 0.01); there was an interaction between the effect of module and language preference (P < 0.01) indicating that although scores increased for both of the topic areas for the English-speaking workers, only the score for the animal health topic increased for the Spanish-speaking workers. Regardless of nationality, level of formal education, topic, or preferred language, digital media are effective at improving knowledge transfer to animal care professionals
Cooper-pair insulator phase in superconducting amorphous Bi films induced by nanometer-scale thickness variations
Ultrathin films near the quantum insulator-superconductor transition (IST) can exhibit Cooper-pair transport in their insulating state. This Cooper-pair insulator (CPI) state is achieved in amorphous Bi films evaporated onto substrates with a topography varying on lengths slightly greater than the superconducting coherence length. We present evidence that this topography induces film thickness and corresponding superconducting coupling constant variations that promote Cooper-pair island formation. Analyses of many thickness-tuned ISTs show that weak links between superconducting islands dominate the transport. In particular, the IST occurs when the link resistance approaches the resistance quantum for pairs. These results support conjectures that the CPI is an inhomogeneous state of matter
Observation of giant positive magnetoresistance in a Cooper pair insulator.
Ultrathin amorphous Bi films, patterned with a nanohoneycomb array of holes, can exhibit an insulating phase with transport dominated by the incoherent motion of Cooper pairs (CP) of electrons between localized states. Here, we show that the magnetoresistance (MR) of this Cooper pair insulator (CPI) phase is positive and grows exponentially with decreasing temperature T, for T well below the pair formation temperature. It peaks at a field estimated to be sufficient to break the pairs and then decreases monotonically into a regime in which the film resistance assumes the T dependence appropriate for weakly localized single electron transport. We discuss how these results support proposals that the large MR peaks in other unpatterned, ultrathin film systems disclose a CPI phase and provide new insight into the CP localization
Observation of a subgap density of states in superconductor-normal metal bilayers in the Cooper limit
We present transport and tunneling measurements of Pb-Ag bilayers with
thicknesses, and , that are much less than the superconducting
coherence length. The transition temperature, , and energy gap, ,
in the tunneling Density of States (DOS) decrease exponentially with
at fixed . Simultaneously, a DOS that increases linearly from the Fermi
energy grows and fills nearly 40% of the gap as is 1/10 of of bulk
Pb. This behavior suggests that a growing fraction of quasiparticles decouple
from the superconductor as goes to 0. The linear dependence is consistent
with the quasiparticles becoming trapped on integrable trajectories in the
metal layer.Comment: 5 pages and 4 figures. This version is just the same as the old
version except that we try to cut the unnecessary white space in the figures
and make the whole paper look more compac
Effect of Magnetic Impurities on Suppression of the Transition Temperature in Disordered Superconductors
We calculate the first-order perturbative correction to the transition
temperature in a superconductor with both non-magnetic and magnetic
impurities. We do this by first evaluating the correction to the effective
potential, , and then obtain the first-order correction to the
order parameter, , by finding the minimum of . Setting
finally allows to be evaluated. is now a function of
both the resistance per square, , a measure of the non-magnetic
disorder, and the spin-flip scattering rate, , a measure of the
magnetic disorder. We find that the effective pair-breaking rate per magnetic
impurity is virtually independent of the resistance per square of the film, in
agreement with an experiment of Chervenak and Valles. This conclusion is
supported by both the perturbative calculation, and by a non-perturbative
re-summation technique.Comment: 29 pages, 9 figure
Cooper pair insulator in amorphous films induced by nanometer-scale thickness variations
Unusual transport properties of superconducting (SC) materials, such as the
under doped cuprates, low dimensional superconductors in strong magnetic
fields, and insulating films near the Insulator Superconductor Transition
(IST), have been attributed to the formation of inhomogeneous phases.
Difficulty correlating the behaviors with observations of the inhomogeneities
make these connections uncertain. Of primary interest here are proposals that
insulating films near the IST, which show an activated resistance and giant
positive magnetoresistance, contain islands of Cooper Pairs (CPs). Here we
present evidence that these types of inhomogeneities are essential to such an
insulating phase in amorphous Bi (a-Bi) films deposited on substrates patterned
with nanometer-sized holes. The patterning induces film thickness variations,
and corresponding coupling constant variations, that transform the composition
of the insulator from localized electrons to CPs. Analyses near the
thickness-tuned ISTs of films on nine different substrates show that weak links
between SC islands dominate the transport. In particular, the ISTs all occur
when the link resistance approaches the resistance quantum for pairs. These
observations lead to a detailed picture of CPs localized by spatial variations
of the superconducting coupling constant.Comment: 4 pages, 3 figures, 1 supplemental page with 1 supplemental figur
Magnetic Flux Periodic Response of Nano-perforated Ultrathin Superconducting Films
We have patterned a hexagonal array of nano-scale holes into a series of
ultrathin, superconducting Bi/Sb films with transition temperatures 2.65 K
5 K. These regular perforations give the films a phase-sensitive
periodic response to an applied magnetic field. By measuring this response in
their resistive transitions, , we are able to distinguish regimes in
which fluctuations of the amplitude, both the amplitude and phase, and the
phase of the superconducting order parameter dominate the transport. The
portion of dominated by amplitude fluctuations is larger in lower
films and thus, grows with proximity to the superconductor to
insulator transition.Comment: Revised title, abstract, text, figure
Pathologies of acute interstitial pneumonia in feedlot cattle
Citation: Valles, J. A., Apley, M. D., Reinhardt, C. D., Bartle, S. J., & Thomson, D. U. (2016). Pathologies of acute interstitial pneumonia in feedlot cattle. American Journal of Animal and Veterinary Sciences, 11(1), 1-7. doi:10.3844/ajavsp.2016.1.7Acute Interstitial Pneumonia (AIP) is a costly issue that affects feedlot cattle. Research has yet to elucidate the etiology of AIP; therefore a case-control study was conducted to evaluate possible management and physiological factors that contribute to AIP in feedlot cattle. The experiment was conducted during the summer of 2011 in a commercial feedyard in Kansas. Animals exhibiting clinical signs of AIP and a control animal from the same pen were selected for ante-mortem examination. Post-mortem AIP cases were also selected for additional examination. Ante-mortem measurements included rumen gas cap hydrogen sulfide and pH, rectal temperature and body weight. Post-mortem examination added histological examination of lung tissue. Rectal temperature was greater in the AIP cattle (40.6±0.16°C) than controls (39.7±0.16°C; p0.10). Post-mortem rumen pH values were 6.3±0.4 and 5.7±0.6 for AIP and control cattle, respectively. Histological evaluation of lung samples showed that bronchiolitis was present in about 90% of the cattle affected with AIP. About 75% of the cattle with AIP also had bronchopneumonia. No relationships between feed intake patterns, or serum amylase or lipase levels were noted between treatments (p>0.20). This study generally confirms that AIP tends to occur more in heifers relative to steers, occurs in cattle at heavier weights or later in the feeding period and tends to be associated pathologically with bronchio’ litis and bronchopneumonia. The lack of differences in rumen measures and the feed intake data between AIP and control cattle suggest that feed intake patterns and rumen fermentation may not impact AIP in feedlot cattle and that it may be more directly related to bronchiolitis/bronchopneumonia due to chronic irritation or infection. © 2016 Jose A. Valles, Michael D. Apley, Chris D. Reinhardt, Steven J. Bartle and Daniel U. Thomson
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