Identification of Economic Shocks by Inequality Constraints in Bayesian Structural Vector Autoregression

Theories often make predictions about the signs of the effects of economic shocks on observable variables, thus implying inequality constraints on the parameters of a structural vector autoregression (SVAR). We introduce a new Bayesian procedure to evaluate the probabilities of such constraints, and, hence, to validate the theoretically implied economic shocks. We first estimate a SVAR, where the shocks are identified by statistical properties of the data, and subsequently label these statistically identified shocks by the Bayes factors calculated from their probabilities of satisfying given inequality constraints. In contrast to the related sign restriction approach that also makes use of theoretically implied inequality constraints, no restrictions are imposed. Hence, it is possible that only a subset or none of the theoretically implied shocks can be labelled. In the latter case, we conclude that the data do not lend support to the theory implying the signs of the effects in question. We illustrate the method by empirical applications to the crude oil market, and U.S. monetary policy.Peer reviewe

Fissurectomy combined with botulinum toxin A:a review of short- and long-term efficacy of this treatment strategy for chronic anal fissure; a consecutive proposal of a treatment algorithm for chronic anal fissure

Background Several studies have investigated the short- and long-term efficacy of fissurectomy combined with botulinum toxin A injection for patients with chronic anal fissure. Objective To evaluate the short- and long-term efficacy of the combined treatment strategy of fissurectomy with botulinum toxin A for chronic anal fissure and to discuss recurrence rates in the light of current theory on the aetiology of anal fissure. Materials and methods This is a narrative review. We conducted an article search using PubMed and calculated the means of the reported efficacy ranges. Results Fissurectomy combined with botulinum toxin A injections freed at least 78% of the patients from symptoms and yielded a fissure healing rate of up to 86%. Within 12 months after treatment a 3% recurrence rate was reported. On average, the long-term recurrence rate was 22%. One study reported a 50% recurrence rate 22 months after treatment. Conclusion The efficacy of fissurectomy combined with botulinum toxin A injection for chronic anal fissure is high. The short-term recurrence rate is low, while long-term recurrence is relatively high. Extended follow-up indicates that recurrence of chronic anal fissure is possibly caused by anal basal pressure building up steadily once again. If so, the cause of renewed increase of pressure should be addressed. Based on the literature and on our clinical experience, we assume that the underlying cause of increasing anal basal pressure is that patients use their pelvic floor muscles inadequately and this in turn leads to chronic anal fissure

A novel model to predict the physical state of atmospheric H2SO4/NH3/H2O aerosol particles

Colberg CA, Luo BP, Wernli H, Koop T, Peter T. A novel model to predict the physical state of atmospheric H2SO4/NH3/H2O aerosol particles. ATMOSPHERIC CHEMISTRY AND PHYSICS. 2003;3(4):909-924.The physical state of the tropospheric aerosol is largely unknown despite its importance for cloud formation and for the aerosol's radiative properties. Here we use detailed microphysical laboratory measurements to perform a systematic global modelling study of the physical state of the H2SO4/NH3/H2O aerosol, which constitutes an important class of aerosols in the free troposphere. The Aerosol Physical State Model (APSM) developed here is based on Lagrangian trajectories computed from ECMWF (European Centre for Medium Range Weather Forecasts) analyses, taking full account of the deliquescence/efflorescence hysteresis. As input APSM requires three data sets: (i) deliquescence and efflorescence relative humidities from laboratory measurements, (ii) ammonia-to-sulfate ratios (ASR) calculated by a global circulation model, and (iii) relative humidities determined from the ECMWF analyses. APSM results indicate that globally averaged a significant fraction (17-57%) of the ammoniated sulfate aerosol particles contain solids with the ratio of solid-containing to purely liquid particles increasing with altitude (between 2 and 10 km). In our calculations the most abundant solid is letovicite, (NH4)(3)H(SO4)(2), while there is only little ammonium sulfate, (NH4)(2)SO4. Since ammonium bisulfate, NH4HSO4, does not nucleate homogeneously, it can only form via heterogeneous crystallization. As the ammonia-to-sulfate ratios of the atmospheric H2SO4/NH3/H2O aerosol usually do not correspond to the stoichiometries of known crystalline substances, all solids are expected to occur in mixed-phase aerosol particles. This work highlights the potential importance of letovicite, whose role as cloud condensation nucleus (CCN) and as scatterer of solar radiation remains to be scrutinized

How Birds Combat Ectoparasites

Birds are plagued by an impressive diversity of ectoparasites, ranging from feather-feeding lice, to feather-degrading bacteria. Many of these ectoparasites have severe negative effects on host fitness. It is therefore not surprising that selection on birds has favored a variety of possible adaptations for dealing with ectoparasites. The functional significance of some of these defenses has been well documented. Others have barely been studied, much less tested rigorously. In this article we review the evidence--or lack thereof--for many of the purported mechanisms birds have for dealing with ectoparasites. We concentrate on features of the plumage and its components, as well as anti-parasite behaviors. In some cases, we present original data from our own recent work. We make recommendations for future studies that could improve our understanding of this poorly known aspect of avian biology

Spin accumulation and spin relaxation in a large open quantum dot

We report electronic control and measurement of an imbalance between spin-up and spin-down electrons in micron-scale open quantum dots. Spin injection and detection were achieved with quantum point contacts tuned to have spin-selective transport, with four contacts per dot for realizing a nonlocal spin-valve circuit. This provides an interesting system for studies of spintronic effects since the contacts to reservoirs can be controlled and characterized with high accuracy. We show how this can be used to extract in a single measurement the relaxation time for electron spins inside a ballistic dot (tau(sf) approximate to 300 ps) and the degree of spin polarization of the contacts (P approximate to 0.8).</p