435 research outputs found
Economic evaluation of the eradication program for bovine viral diarrhea in the Swiss dairy sector
The aim of this study was to conduct an economic evaluation of the BVD eradication program in the Swiss dairy sector. The situation before the start of the program (herd-level prevalence: 20%) served as a baseline scenario. Production models for three dairy farm types were used to estimate gross margins as well as net production losses and expenditures caused by BVD. The total economic benefit was estimated as the difference in disease costs between the baseline scenario and the implemented eradication program and was compared to the total eradication costs in a benefit-cost analysis. Data on the impact of BVD virus (BVDV) infection on animal health, fertility and production parameters were obtained empirically in a retrospective epidemiological case-control study in Swiss dairy herds and complemented by literature. Economic and additional production parameters were based on benchmarking data and published agricultural statistics. The eradication costs comprised the cumulative expenses for sampling and diagnostics. The economic model consisted of a stochastic simulation in @Risk for Excel with 20,000 iterations and was conducted for a time period of 14 years (2008–2021)
An Artificial SEI Layer Based on an Inorganic Coordination Polymer with Self-Healing Ability for Long-Lived Rechargeable Lithium-Metal Batteries
Upon immersion of a lithium (Li) anode into a diluted 0.05 to 0.20 M dimethoxyethane solution of the phosphoric-acid derivative (CFCHO)P(O)OH (HBFEP), an artificial solid-electrolyte interphase (SEI) is generated on the Li-metal surface. Hence, HBFEP reacts on the surface to the corresponding Li salt (LiBFEP), which is a Li-ion conducting inorganic coordination polymer. This film exhibits – due to the reversibly breaking ionic bonds – self-healing ability upon cycling-induced volume expansion of Li. The presence of LiBFEP as the major component in the artificial SEI is proven by ATR-IR and XPS measurements. SEM characterization of HBFEP-treated Li samples reveals porous layers on top of the Li surface with at least 3 μm thickness. Li−Li symmetrical cells with HBFEP-modified Li electrodes show a three- to almost fourfold cycle-lifetime increase at 0.1 mA cm in a demanding model electrolyte that facilitates fast battery failure (1 M LiOTf in TEGDME). Hence, the LiBFEP-enriched layer apparently acts as a Li-ion conducting protection barrier between Li and the electrolyte, enhancing the rechargeability of Li electrodes
Same legal status but unequal treatment: bureaucratic discrimination against mobile EU citizens
EU Citizenship guarantees the same rights to all mobile EU citizens who move to another member state. And yet, as a recent study by Christian Adam, Xavier Fernández-i-Marín, Oliver James, Anita Manatschal, Carolin Rapp and Eva Thomann indicates, some EU citizens are more likely than others to face discrimination when interacting with their host country’s public administration. Remarkably, they find that patterns of discrimination displayed by public administrators are very similar to patterns of discriminatory behaviour displayed by the general public
Quantum instability in a dc-SQUID with strongly asymmetric dynamical parameters
A classical system cannot escape out of a metastable state at zero
temperature. However, a composite system made from both classical and quantum
degrees of freedom may drag itself out of the metastable state by a sequential
process. The sequence starts with the tunneling of the quantum component which
then triggers a distortion of the trapping potential holding the classical
part. Provided this distortion is large enough to turn the metastable state
into an unstable one, the classical component can escape. This process reminds
of the famous baron Muenchhausen who told the story of rescuing himself from
sinking in a swamp by pulling himself up by his own hair--we thus term this
decay the `Muenchhausen effect'. We show that such a composite system can be
conveniently studied and implemented in a dc-SQUID featuring asymmetric
dynamical parameters. We determine the dynamical phase diagram of this system
for various choices of junction parameters and system preparations.Comment: 12 pages, 12 figure
EU Referendums in Context: What can we learn from the Swiss Case?
This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordThe rising number of referendums on EU matters, such as the Brexit and the Catalonian independence votes, highlight the increasing importance of referendums as a problem‐solving mechanism in the EU. We argue that the Swiss case provides essential insights into understanding the dynamics behind referendums, which are often lacking when referendums are called for in the EU. Referendums in EU member states on EU matters differ substantially from the in Swiss context. Nevertheless, proponents of more direct democratic decision‐making regularly cite the Swiss example. Our systematic analysis of why referendums are called, how they unfold and their resulting effects in the EU and Switzerland reveals that the EU polity lacks the crucial conditions that embed direct democracy within the wider political and institutional system. The comparative perspective offers fundamental insights into the pre‐conditions required for direct democracy to function and its limitations in the EU
On the elastic moduli of three-dimensional assemblies of spheres: characterization and modeling of fluctuations in the particle displacement and rotation
The elastic moduli of four numerical random isotropic packings of Hertzian
spheres are studied. The four samples are assembled with different preparation
procedures, two of which aim to reproduce experimental compaction by vibration
and lubrication. The mechanical properties of the samples are found to change
with the preparation history, and to depend much more on coordination number
than on density.
Secondly, the fluctuations in the particle displacements from the average
strain are analysed, and the way they affect the macroscopic behavior analyzed.
It is found that only the average over equally oriented contacts of the
relative displacement these fluctuations induce is relevant at the macroscopic
scale. This average depends on coordination number, average geometry of the
contact network and average contact stiffness. As far as the separate
contributions from particle displacements and rotations are concerned, the
former is found to counteract the average strain along the contact normal,
while the latter do in the tangential plane. Conversely, the tangential
components of the center displacements mainly arise to enforce local
equilibrium, and have a small, and generally stiffening effect at the
macro-scale.
Finally, the fluctuations and the shear modulus that result from two
approaches available in the literature are estimated numerically. These
approaches are both based on the equilibrium of a small-sized representative
assembly. The improvement of these estimate with respect to the average strain
assumption indicates that the fluctuations relevant to the macroscopic behavior
occur with short correlation length.Comment: Submitted to IJS
Time-Resolved Coherent Photoelectron Spectroscopy of Quantized Electronic States on Metal Surfaces
Time-resolved two-photon photoemission in combination with the coherent excitation of several quantum states was used to study the ultrafast electron dynamics of imagepotential states on metal surfaces. For a (100) surface of copper, the spectroscopy of quantum beats made previously unresolved high-order states (quantum number n Ն 4) experimentally accessible. By exciting electrons close to the vacuum level, electron wave packets could be created and detected that described the quasi-classical periodic motion of weakly bound electrons. They traveled more than 200 Å away from the surface and oscillated back and forth with a period of 800 femtoseconds. Photoelectron spectroscopy has developed into one of the most versatile and successful tools for surface studies. Particularly attractive features of this technique are the high surface sensitivity associated with the low escape depth of the photoelectrons and the capability of angle-resolved photoemission to completely characterize electronic states in energy and momentum space (1). Recently, these features have been combined with ultrafast laser excitation for direct time-domain investigations of electron dynamics at surfaces (2). Here, we demonstrate another facet of this powerful technique, the investigation of coherence phenomena in real time. In contrast to experimental methods that rely merely on intensities, coherent spectroscopies offer the unique capability of accessing not only the amplitudes but also the phases of the wave functions of interest (3). This technique dramatically increases the amount of information that one is able to obtain about the temporal evolution of fast processes. In this report, we discuss the dynamics of image-potential states, that is, the quantized excited states of electrons that exist in front of many metal surfaces (4, 5). Using femtosecond time-resolved two-photon photoemission (2PPE), we observed the interference between the wave functions of neighboring eigenstates and the quasi-classical motion of electron wave packets created by the coherent superposition of several quantum states. Recently, the imaging of the static charge density of related surface electronic (ground) states in real space with the scanning tunneling microscope has attracted considerable interest (6); the present results reveal the dynamical evolution of excited electrons in real time. Image-potential states are conceptually rather simple. An electron at a distance z in front of a conducting metal surface experiences an attractive force F(z) ϭ Ϫe 2 /(2z) 2 identical to that produced by a positive (mirror image) charge at a distance z inside the metal converging toward the vacuum energy, where the influence of the surface potential on the binding energy E B ϭ ϪE n is approximated by a quantum defect 0 Յ a Յ 0.5. Experimentally, image-potential states have been studied with 2PPE on many metal surfaces including surfaces covered with adsorbates and metallic overlayers (5, 7-11). One photon with energy ប a (ប is Planck's constant h divided by 2 and is the photon frequency times 2) excites an electron out of an occupied state below the Fermi energy E F into the image-potential state n. A second photon with energy ប b excites the electron to an energy above E vac The experimental setup consisted of a 80-MHz Ti:sapphire laser system that generated infrared (IR) pulses of 70-fs duration. Frequency-tripled 95-fs ultraviolet (UV) pulses from this laser were used for the excitation step (ប a ϭ 4.7 eV). The photoelectrons were emitted by the fundamental IR pulses (ប b ϭ 1.57 eV) and were detected in a hemispherical analyzer with an energy resolution of 30 meV and an angular acceptance of Ϯ0.6°about the surface normal. The preparation of the Cu(111) and Cu(100) samples and details of the ultrahigh-vacuum chamber have been described elsewhere (5). The samples were kept at room temperature. Typical energy-resolved 2PPE spectra of C
Internal states of model isotropic granular packings. III. Elastic properties
In this third and final paper of a series, elastic properties of numerically
simulated isotropic packings of spherical beads assembled by different
procedures and subjected to a varying confining pressure P are investigated. In
addition P, which determines the stiffness of contacts by Hertz's law, elastic
moduli are chiefly sensitive to the coordination number, the possible values of
which are not necessarily correlated with the density. Comparisons of numerical
and experimental results for glass beads in the 10kPa-10MPa range reveal
similar differences between dry samples compacted by vibrations and lubricated
packings. The greater stiffness of the latter, in spite of their lower density,
can hence be attributed to a larger coordination number. Voigt and Reuss bounds
bracket bulk modulus B accurately, but simple estimation schemes fail for shear
modulus G, especially in poorly coordinated configurations under low P.
Tenuous, fragile networks respond differently to changes in load direction, as
compared to load intensity. The shear modulus, in poorly coordinated packings,
tends to vary proportionally to the degree of force indeterminacy per unit
volume. The elastic range extends to small strain intervals, in agreement with
experimental observations. The origins of nonelastic response are discussed. We
conclude that elastic moduli provide access to mechanically important
information about coordination numbers, which escape direct measurement
techniques, and indicate further perspectives.Comment: Published in Physical Review E 25 page
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