3,766 research outputs found
Some Methods for Assessing the Need for Non-linear Models in Business Cycle Analysis and Forecasting
There is a long tradition in business cycle analysis of arguing that non-linear models are needed to explain the business cycle. In recent years many non-linear models have been fitted to data on GDP for many countries, but particularly for the U.S. In this paper we set our criteria to evaluate the success of non-linear models in explaining the cycle and then evaluate three recent models in the light of these criteria. We find that the models are capable of explaining the "shape" of expansions, something linear models cannot do, but do so at the cost of making expansions longer than they should be and in producing transition probabilities to recessions that are too low.business cyles, non-linear models
Phase Behavior of Short Range Square Well Model
Various Monte Carlo techniques are used to determine the complete phase
diagrams of the square well model for the attractive ranges
and . The results for the latter case are in agreement with
earlier Monte Carlo simulations for the fluid-fluid coexistence curve and yield
new results for the liquidus-solidus lines. Our results for
are new. We find that the fluid-fluid critical point is metastable for both
cases, with the case being just below the threshold value for
metastability. We compare our results with prior studies and with experimental
results for the gamma-II crystallin.Comment: 8 figures, 1 tabl
A Finite-Size Scaling Study of a Model of Globular Proteins
Grand canonical Monte Carlo simulations are used to explore the metastable
fluid-fluid coexistence curve of the modified Lennard-Jones model of globular
proteins of ten Wolde and Frenkel (Science, v277, 1975 (1997)). Using both
mixed-field finite-size scaling and histogram reweighting methods, the joint
distribution of density and energy fluctuations is analyzed at coexistence to
accurately determine the critical-point parameters. The subcritical coexistence
region is explored using the recently developed hyper-parallel tempering Monte
Carlo simulation method along with histogram reweighting to obtain the density
distributions. The phase diagram for the metastable fluid-fluid coexistence
curve is calculated in close proximity to the critical point, a region
previously unattained by simulation.Comment: 17 pages, 10 figures, 2 Table
PiggyBac-ing on a Primate Genome: Novel Elements, Recent Activity and Horizontal Transfer
To better understand the extent of Class II transposable element activity in mammals, we investigated the mouse lemur, Microcebus murinus, whole genome shotgun (2X) draft assembly. Analysis of this strepsirrhine primate extended previous research that targeted anthropoid primates and found no activity within the last 37 Myr. We tested the hypothesis that members of the piggyBac Class II superfamily have been inactive in the strepsirrhine lineage of primates during the same period. Evidence against this hypothesis was discovered in the form of three nonautonomous piggyBac elements with activity periods within the past 40 Myr and possibly into the very recent past. In addition, a novel family of piggyBac transposons was identified, suggesting introduction via horizontal transfer. A second autonomous element was also found with high similarity to an element recently described from the little brown bat, Myotis lucifugus, further implicating horizontal transfer in the evolution of this genome. These findings indicate a more complex history of transposon activity in mammals rather than a uniform shutdown of Class II transposition, which had been suggested by analyses of more common model organisms
Beta-blockers to prevent gastroesophageal varices in patients with cirrhosis.
BACKGROUND: Nonselective beta-adrenergic blockers decrease portal pressure and prevent variceal hemorrhage. Their effectiveness in preventing varices is unknown. METHODS: We randomly assigned 213 patients with cirrhosis and portal hypertension (minimal hepatic venous pressure gradient [HVPG] of 6 mm Hg) to receive timolol, a nonselective beta-blocker (108 patients), or placebo (105 patients). The primary end point was the development of gastroesophageal varices or variceal hemorrhage. Endoscopy and HVPG measurements were repeated yearly. RESULTS: During a median follow-up of 54.9 months, the rate of the primary end point did not differ significantly between the timolol group and the placebo group (39 percent and 40 percent, respectively; P=0.89), nor were there significant differences in the rates of ascites, encephalopathy, liver transplantation, or death. Serious adverse events were more common among patients in the timolol group than among those in the placebo group (18 percent vs. 6 percent, P=0.006). Varices developed less frequently among patients with a baseline HVPG of less than 10 mm Hg and among those in whom the HVPG decreased by more than 10 percent at one year and more frequently among those in whom the HVPG increased by more than 10 percent at one year. CONCLUSIONS: Nonselective beta-blockers are ineffective in preventing varices in unselected patients with cirrhosis and portal hypertension and are associated with an increased number of adverse events. (ClinicalTrials.gov number, NCT00006398.
Quantifying the speech-gesture relation with massive multimodal datasets: informativity in time expressions
The development of large-scale corpora has led to a quantum leap in our understanding of speech in recent years. By contrast, the analysis of massive datasets has so far had a lim- ited impact on the study of gesture and other visual communicative behaviors. We utilized the UCLA-Red Hen Lab multi-billion-word repository of video recordings, all of them showing communicative behavior that was not elicited in a lab, to quantify speech-gesture co-occur- rence frequency for a subset of linguistic expressions in American English. First, we objec- tively establish a systematic relationship in the high degree of co-occurrence between gesture and speech in our subset of expressions, which consists of temporal phrases. Sec- ond, we show that there is a systematic alignment between the informativity of co-speech gestures and that of the verbal expressions with which they co-occur. By exposing deep, systematic relations between the modalities of gesture and speech, our results pave the way for the data-driven integration of multimodal behavior into our understanding of human communication
Multiple agency perspective, family control, and private information abuse in an emerging economy
Using a comprehensive sample of listed companies in Hong Kong this paper investigates how family control affects private information abuses and firm performance in emerging economies. We combine research on stock market microstructure with more recent studies of multiple agency perspectives and argue that family ownership and control over the board increases the risk of private information abuse. This, in turn, has a negative impact on stock market performance. Family control is associated with an incentive to distort information disclosure to minority shareholders and obtain private benefits of control. However, the multiple agency roles of controlling families may have different governance properties in terms of investors’ perceptions of private information abuse. These findings contribute to our understanding of the conflicting evidence on the governance role of family control within a multiple agency perspectiv
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