926 research outputs found
The Swiss National Bank's monetary policy concept - an example of a 'principles-based' policy framework
The practice of monetary policy has evolved a great deal since the early 1990s. This evolution was significantly influenced by rapid developments in the theory of monetary policy. A new consensus about 'principles-based' monetary policy appears to be emerging. It marries a firm long-term anchor for nominal stability, rooted in the original ideas behind inflation targeting, with short-term flexibility, based on a more discretionary and pragmatic approach to monetary policy. The SNB's monetary policy framework - with a firm nominal anchor but with an emphasis on the need for flexibility - reflects, to a considerable degree, the emerging academic consensus about best-practice monetary policy. With its successful seven-year track record, it may serve as an interesting case study for a policy aiming at an intermediate position between full discretion and rigidly defined short-term inflation targeting.Swiss National Bank, monetary policy, inflation targeting, rules, discretion
Magnetic-induced phonon anisotropy in ZnCrO from first principles
We have studied the influence of magnetic order on the optical phonons of the
geometrically frustrated spinel ZnCrO from first-principles. By mapping
the first-principles phonon calculations onto a Heisenberg-like model, we
developed a method to calculate exchange derivatives and subsequently the
spin-phonon couping parameter from first-principles. All calculations were
performed within LSDA+U
Evaluating chickpea lines for disease resistance in western Nebraska
Chickpeas (Cicer arietinum) are a newly emerging alternative crop for western Nebraska. Interest in this crop is increasing with approximately 4,000 hectares cropped per year over the last 5 seasons. Several disease problems have been identified that will limit optimal production success if left unchecked. These diseases include Ascochyta blight, caused by A. rabiei, and a root disease complex consisting of Rhizoctonia solani, Fusarium spp., and Pythium spp. Thus trials were conducted at multiple locations (2003–2004) throughout the Nebraska Panhandle for testing chickpea lines and cultivars for yield potential and tolerance to both types of diseases under both dryland and irrigated conditions. Differences were observed between entries and their yield response to the different irrigation systems. In general, those entries with better root disease tolerance tended to yield better from irrigated production, while those more susceptible to disease performed better under dryland conditions. Identification of better sources of resistance is encouraging for the new chickpea industry in Nebraska and this process will continue as interest and production expands
13-month climatology of the aerosol hygroscopicity at the free tropospheric site Jungfraujoch (3580 m a.s.l.)
A hygroscopicity tandem differential mobility analyzer (HTDMA) was operated at the high-alpine site Jungfraujoch in order to characterize the hygroscopic diameter growth factors of the free tropospheric Aitken and accumulation mode aerosol. More than ~5000 h of valid data were collected for the dry diameters <i>D</i><sub>0</sub> = 35, 50, 75, 110, 165, and 265 nm during the 13-month measurement period from 1 May 2008 through 31 May 2009. No distinct seasonal variability of the hygroscopic properties was observed. Annual mean hygroscopic diameter growth factors (<i>D</i>/<i>D</i><sub>0</sub>) at 90% relative humidity were found to be 1.34, 1.43, and 1.46 for <i>D</i><sub>0</sub> = 50, 110, and 265 nm, respectively. This size dependence can largely be attributed to the Kelvin effect because corresponding values of the hygroscopicity parameter κ are nearly independent of size. The mean hygroscopicity of the Aitken and accumulation mode aerosol at the free tropospheric site Jungfraujoch was found to be &kappa;≈0.24 with little variability throughout the year. <br><br> The impact of Saharan dust events, a frequent phenomenon at the Jungfraujoch, on aerosol hygroscopicity was shown to be negligible for <i>D</i><sub>0</sub><265 nm. Thermally driven injections of planetary boundary layer (PBL) air, particularly observed in the early afternoon of summer days with convective anticyclonic weather conditions, lead to a decrease of aerosol hygroscopicity. However, the effect of PBL influence is not seen in the annual mean hygroscopicity data because the effect is small and those conditions (weather class, season and time of day) with PBL influence are relatively rare. <br><br> Aerosol hygroscopicity was found to be virtually independent of synoptic wind direction during advective weather situations, i.e. when horizontal motion of the atmosphere dominates over thermally driven convection. This indicates that the hygroscopic behavior of the aerosol observed at the Jungfraujoch can be considered representative of the lower free troposphere on at least a regional if not continental scale
Observations on pulpal response to carbon dioxide laser drilling of dentine in healthy human third molars
Preservation of pulpal health is the primary prerequisite for successful application of laser systems in the hard tissue management of vital teeth. The purpose of this study was to investigate the short and long-term pulpal effects to cavity preparations in healthy human teeth using carbon dioxide (CO2) laser. A total of seven, healthy, third molars that were scheduled to be removed due to space problems were used. After the laser drilling, the occlusal cavities were closed temporarily, and the teeth were extracted 7days (n=5) and 3 months (n=2) after the operation. The specimens were fixed, decalcified, subdivided and processed for light and transmission electron microscopy. Seven days postoperatively all the five teeth that had been irradiated with the CO2 laser did not reveal any pathological changes in the pulpo-dentine complex. Three months postoperatively the two teeth that were prepared with the laser showed subtle but distinct apposition of tertiary dentine that was lined with intact odontoblasts. One of the specimens at 3 months revealed the presence of a mild, but very circumscribed, pulpal infiltration of chronic inflammatory cells subjacent to the cavity preparation. The latter is unlikely to be due to a direct effect of the laser irradiation but a possible consequence of microleakage of oral antigens and/or other tissue-irritating molecules through the temporary restoration and the remaining dentine thickness (RDT). Although these preliminary histological results suggest that the CO2 laser under investigation induced only minimal response of the dentine-pulp complex when used as a hard-tissue drilling tool, with specific energy settings, pulse duration within thermal relaxation time and emitting radiations at 9.6μm of wavelength, larger clinical trials involving various types of teeth are necessary to reach definite conclusions for large-scale clinical application of the laser devic
Spin-Electron-Phonon Excitation in Re-based Half-Metallic Double Perovskites
A remarkable hardening (~ 30 cm-1) of the normal mode of vibration associated
with the symmetric stretching of the oxygen octahedra for the Ba2FeReO6 and
Sr2CrReO6 double perovskites is observed below the corresponding magnetic
ordering temperatures. The very large magnitude of this effect and its absence
for the anti-symmetric stretching mode provide evidence against a conventional
spin-phonon coupling mechanism. Our observations are consistent with a
collective excitation formed by the combination of the vibrational mode with
oscillations of local Fe or Cr 3d and Re 5d occupations and spin magnitudes.Comment: 12 pages, 4 figure
Manure Impacts on Interrill Erosion
This study was conducted to measure runoff and erosion from interrill areas as affected by the long-term application of manure and fertilizer to a Tripp sandy loam soil located near Mitchell, Nebraska. Soil that had been removed from the top 0.1 m of the soil profile was placed in a 1 m2 soil pan. Rainfall was then applied to the soil pan during initial and wet simulation events. Total runoff was similar on the manure and no-manure treatments. The long-term application of manure (55 years) at a rate of 27 Mg ha-1 (wet basis) per year did not significantly influence interrill erosion on this sandy loam soil. Interrill erosion was also unaffected by the addition of manure immediately before rainfall simulation tests to soils on which manure had been applied in previous years. No significant differences in runoff and erosion were found among plots receiving varying amounts of fertilizer. Selected soil properties were generally unaffected by the varying manure and fertilizer treatments
Effect of magnetic order on the superfluid response of single-crystal ErNiBC: A penetration depth study
We report measurements of the in-plane magnetic penetration depth (T) in single crystals of ErNiBC down to 0.1 K using
a tunnel-diode based, self-inductive technique at 21 MHz. We observe four
features: (1) a slight dip in (T) at the Nel
temperature = 6.0 K, (2) a peak at = 2.3 K, where a weak
ferromagnetic component sets in, (3) another maximum at 0.45 K, and (4) a final
broad drop down to 0.1 K. Converting to superfluid density , we see
that the antiferromagnetic order at 6 K only slightly depresses
superconductivity. We seek to explain some of the above features in the context
of antiferromagnetic superconductors, where competition between the
antiferromagnetic molecular field and spin fluctuation scattering determines
increased or decreased pairbreaking. Superfluid density data show only a slight
decrease in pair density in the vicinity of the 2.3 K feature, thus supporting
other evidences against bulk ferromagnetism in this temperature range.Comment: 15 pages, 5 figure
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