We present updated estimates of central bank for 100 countries up through 2006 and use them to analyze both the determinant and consequences of monetary policy transparency in an integrated econometric framework. We establish that there has been significant movement in the direction of greater central bank transparency in recent years. Transparent monetary policy arrangements are more likely in countries with strong and stable political institutions. They are more likely in democracies, with their culture of transparency. Using these political determinants as instruments for transparency, we show that more transparency monetary policy operating procedures are associated with less inflation variability though not also with less inflation persistence.
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Trypsin immobilization onto continuous "molded" rods of porous poly(glycidyl methacrylate-co-ethylene dimethacrylate) and some applications of the conjugate have been studied. The rods polymerized within a tubular mold (chromatographic column), were treated in situ with ethylenediamine, activated with glutaraldehyde and finally modified with trypsin. The performance of the trypsin-modified rods was evaluated and compared to that of poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads, modified with the same enzyme. Overall the enzyme-modified rods performed substantially better than the corresponding beads. In particular, the performance of the molded supports as enzymatic reactors or as chromatographic media benefits greatly from the enhanced mass transfer that is characteristic of the molded rod at high flow rates. © 1996 John Wiley & Sons, Inc.
The surface nanomechanical properties and morphology of ∼500-μm-thick polyurethane films subjected to normal loads in the range of 3–35 nN and longitudinal strains up to 150% were investigated with an atomic force microscope. Nanoindentation experiments performed at very low loads and small penetration depths demonstrated that the elastic behavior of the polyurethane surface is remarkably different from that of the bulk material. The distinctly different mechanical response to applied pressure between surface and near-surface (bulk) regions of the polymer is attributed to packing of the polymer chains at the contact region. The polyurethane copolymer consists of two immiscible hard and soft segments. It is suggested that upon stretching, randomly oriented hard segments migrate to the surface, leading to an increase of the hard-to-soft segment concentration and a decrease of the surface roughness. A general description of the polyurethane surface and bulk behavior under stretching and compression is presented in the context of the obtained results.
In this paper, we present a technique for recovering a model of shape, illumination, reflectance, and shading from a single image taken from an RGB-D sensor. To do this, we extend the SIRFS ("shape, illumination and reflectance from shading") model, which recovers intrinsic scene properties from a single image. Though SIRFS works well on neatly segmented images of objects, it performs poorly on images of natural scenes which often contain occlusion and spatially-varying illumination. We therefore present Scene-SIRFS, a generalization of SIRFS in which we model a scene using a mixture of shapes and a mixture of illuminations, where those mixture components are embedded in a "soft" segmentation-like representation of the input image. We use the noisy depth maps provided by RGB-D sensors (such as the Microsoft Kinect) to guide and improve shape estimation. Our model takes as input a single RGB-D image and produces as output an improved depth map, a set of surface normals, a reflectance image, a shading image, and a spatially varying model of illumination. The output of our model can be used for graphics applications such as relighting and retargeting, or for more broad applications (recognition, segmentation) involving RGB-D images.
Implicit probabilistic models are models defined naturally in terms of a sampling procedure and often induces a likelihood function that cannot be expressed explicitly. We develop a simple method for estimating parameters in implicit models that does not require knowledge of the form of the likelihood function or any derived quantities, but can be shown to be equivalent to maximizing likelihood under some conditions. Our result holds in the non-asymptotic parametric setting, where both the capacity of the model and the number of data examples are finite. We also demonstrate encouraging experimental results.
I present spectra of SN 1987K in NGC 4651 obtained 0-2 weeks past maximum brightness, and also 5-7 months past maximum. The early spectra resemble those of Type II supernovae (SNe II), with broad Hα having a well-defined P Cygni profile that appears less prominent than usual. Two weeks past maximum, the Hα emission-line and absorption-line strengths are much smaller than those in SN 1987A. At late times, no trace of the broad Hα can be found; instead, very broad emission lines of [O I] and [Ca II] dominate the spectrum. These last characteristics are typical of Type Ib supernovae long past maximum, although SNe Ib were previously thought to lack hydrogen lines at all times. The data strongly suggest, but do not prove, that SNe II and at least some SNe Ib are closely related objects. In particular, SN 1987K could have been a massive star which lost a majority of its hydrogen prior to exploding. The light curve declined more slowly after maximum than in SNe I, but not as slowly as in typical SNe II-P ("plateau"), consistent with the presence of a thin envelope. Spectra of the Type Ib SNe 1983I, 1987M, and 1988L may provide additional evidence that SNe II and SNe Ib form a continuous sequence in which the mass of the hydrogen envelope is the main variable: extremely weak Hα appears to be present in these objects near maximum light. It is also possible that SNe Ib arise from two very different types of progenitors with dissimilar explosion mechanisms. SN 1987K is proposed as the prototype of a new subclass, Type IIb, of supernovae that have the spectral characteristics of Type II near maximum brightness and those of Type Ib long past maximum.
Abstract A nonlinear lumped circuit model for Gunn diodes which includes the effects due to domain extinction and nucleation phenomena is presented. The model is based upon physical principles and allows an arbitrary nonlinear drift velocity curve v ( E ) and a nonlinear diffusion curve D(E) to be specified by the user. It is valid for simulating arbitrary Gunn‐diode circuits operating in any matured high‐field domain mode, or in the LSA mode. Under additional assumptions, the model simplifies to other existing models. Several computer‐simulated examples of Gunn‐diode circuits operating under both steady‐state and transient regimes are presented. Finally, a rigorous definition of a ‘DC’ I‐V curve for Gunn diodes is offered and shown to be rather useful for predicting the qualitative behaviour of Gunn‐diode circuits during all time intervals where a matured domain exists.
