171,251 research outputs found
An Optimising Model for Monetary Policy Analysis: Can Habit Formation Help?
No full textIn earlier work (Fuhrer 1997a), I document what I view as the failure of standard models of representative consumer and firm behaviour to replicate the dynamics that we observe in the aggregate data. In essence, these models fail because they imply that both inflation and real variables must ‘jump’ in response to monetary policy (and other) shocks, in contrast to identified VAR evidence that shows a gradual, ‘hump shaped’ response. This paper discusses a rigorous empirical standard for monetary policy models. The motivation for this discussion is that, if one wishes to conduct welfare analysis, one must be reasonably confident that the model provides a good approximation to underlying consumer and firm behaviour over the monetary policy horizon, i.e. in the short run. The paper examines a specific alternative to the standard consumption model in which consumers’ utility depends in part on current consumption relative to past consumption. This formulation of habit formation allows one to nest habit formation, life-cycle consumption, and Campbell and Mankiw’s ‘rule of thumb’ consumers within a more general model. The empirical tests developed in the paper show that one can reject the hypothesis of no habit formation with tremendous confidence. This result suggests that models that are unable to produce a hump-shaped response will be strongly rejected empirically.consumer behaviour; habit formation; monetary policy
Towards a compact, empirically verified rational expectations model for monetary policy analysis
No full textThis paper extends the sticky-price models of Fuhrer and Moore (1995a,b) to include explicit, optimization-based consumption and investment decisions. The goal is to use the resulting model for monetary policy analysis; consequently, strong emphasis is placed on empirical validation of the model. I use a canonical formulation of the consumer's problem from Campbell and Mankiw (1989), and a time-to-build investment model with costs of adjustment. The restrictions imposed by these models, in conjunction with those imposed on prices and output by the Fuhrer-Moore contracting specification, imply dynamic behavior that is grossly inconsistent with the data.Monetary policy ; Rational expectations (Economic theory)
Overview of Recent Field Experiments for the Study of the Air-Snow Transfer of H2O2 and HCHO
No full textThe analysis of hydrogen peroxide and formaldehyde in ice cores offers the potential to reconstruct the oxidation capacity of the atmosphere in the past [Neftel and Fuhrer, 1993], since these species are closely linked to the odd H and the odd O budget of the atmosphere [Thompson, 1992]. These species are so-called reversibly deposited on the snow surface since they show a strong exchange with the gas phase after deposition and their ice concentrations are dominated to a large extent by postdepositional changes in the firn. Therefore, the transfer from the atmosphere into the snow is an important step in the overall transfer function of these species [Neftel, this issue]. To get a better understanding of this step several field experiments were carried out during the 1993 and 1994 summer seasons at Summit in Central Greenland, in the 1993/94 Austral summer in Antarctica along the Swedish traverse (SWEDARP), and at South Pole in November and December, 1994. We will give an overview of the data and point out possible contradictions and knowledge gaps
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
A Note on Inflation Persistence
No full textMacroeconomists have for some time been aware that the New Keynesian Phillips curve, though highly popular in the literature, cannot explain the persistence observed in actual inflation. We argue that two of the more prominent alternative formulations, the Fuhrer and Moore (1995) relative contracting model and the Blanchard and Katz (1999) reservation wage conjecture, are highly problematic. Fuhrer and Moore (1995)'s formulation generates inflation persistence, but this is a consequence of their assuming that workers care about the past real wages of other workers. Making the more reasonable assumption that workers care about the current real wages of other workers, one obtains the standard formulation with no inflation persistence. The Blanchard and Katz conjecture turns out to imply that inflation depends negatively on itself lagged, i.e. the opposite of the empirical regularity.
Alpine grassland soils contain large proportion of labile carbon but indicate long turnover times
No full textAlpine soils are expected to contain large amounts of labile carbon (C) which may become a further source of atmospheric carbon dioxide (CO2) as a result of global warming. However, there is little data available on these soils, and understanding of the influence of environmental factors on soil organic matter (SOM) turnover is limited. We extracted 30 cm deep cores from five grassland sites along a small elevation gradient from 2285 to 2653 m a.s.l. in the central Swiss Alps. Our aim was to determine the quantity, allocation, degree of stabilization and mean residence time (MRT) of SOM in relation to site factors such as soil pH, vegetation, and SOM composition. Soil fractions obtained by size and density fractionation revealed a high proportion of labile C in SOM, mostly in the uppermost soil layers. Labile C in the top 20 cm across the gradient ranged from 39.6–57.6 % in comparison to 7.2–29.6 % reported in previous studies for lower elevation soils (810–1960 m a.s.l.). At the highest elevation, MRTs measured by means of radiocarbon dating and turnover modelling, increased between fractions of growing stability from 90 years in free POM (fPOM) to 534 years in the mineral associated fraction (mOM). Depending on elevation and pH, plant community data suggested considerable variation in the quantity and quality of organic matter input, and these patterns could be reflected in the dynamics of soil C. 13C NMR data confirmed a relationship of SOM composition to MRT. While low temperature in alpine environments is likely to be a major cause for the slow turnover rate observed, other factors such as residue quality and soil pH, as well as the combination of all factors, play an important role in causing small scale variability of SOM turnover. Failing to incorporate this interplay of controlling factors into models may impair the performance of models to project SOM responses to environmental change
Endocytosis of the ASGP receptor H1 is reduced by mutation of tyrosine-5 but still occurs via coated pits
No full textThe clustering of plasma membrane receptors in clathrin-coated pits depends on determinants within their cytoplasmic domains. In several cases, individual tyrosine residues were shown to be necessary for rapid internalization. We have mutated the single tyrosine at position 5 in the cytoplasmic domain of the major subunit H1 of the asialoglycoprotein receptor to alanine. Expressed in fibroblasts cells, the mutant protein was accumulated in the plasma membrane, and its rate of internalization was reduced by a factor of four. The residual rate of endocytosis, however, was still significantly higher than that of resident plasma membrane proteins. Upon acidification of the cytoplasm, which specifically inhibits the formation of clathrin-coated vesicles but not uptake of the fluid phase marker Lucifer yellow, residual endocytosis was blocked. By immunoelectron microscopy mutant H1 could be directly demonstrated in coated pits. The fraction of wild-type and mutant H1 present in coated pits as determined by immunogold localization correlated well with the respective rates of internalization. Thus, mutation of tyrosine-5 only partially inactivates recognition of H1 for incorporation into coated pits
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
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