Search results for "smile"
showing 10 items of 44 documents
Dynamic Volatility Weighting in the Presence of Transaction Costs
2015
Numerous empirical studies demonstrate the superiority of dynamic strategies with volatility weighting over time mechanism. These strategies control the portfolio risk over time by adjusting the risk exposure according to updated volatility forecasts. Yet, in order to reap all benefits promised by volatility weighting over time, the composition of the active portfolio must be revised rather frequently. Transaction costs represent a serious obstacle to benefiting from this dynamic risk control technique. In this paper we propose a modified volatility weighting strategy that allows one to reduce dramatically the amount of trading costs. The empirical evidence shows that the advantages of the …
Effect of posterior gingival smile on the perception of smile esthetics
2013
Objectives: To evaluate and compare the influence of posterior gummy smile on the perception of smile esthetics by orthodontists, general-dentists and laypersons. Study Design: A frontal photograph of a smile with normal gum exposure was chosen and manipulated digitally using Adobe Photoshop C3 to generate three further images with posterior gum exposure of 4, 6 and 8mm. These four images were assessed by the three evaluator groups: orthodontists (n=40), general-dentists (n=40) and laypersons (n=40). Both orthodontists and dentists had at least ten years professional experience and laypersons were aged between 40-50 years. The proportion of men to women was 20:20 in each group. Evaluators a…
Smile esthetics from odontology students' perspectives
2013
ABSTRACT Objectives: To analyze the perception of smile esthetics and its alterations in dental degree students; to determine whether there are differences in that perception among students in different study years on those courses and between genders; and to determine if the circumstance of having received prior orthodontic treatment could influence that perception. Material and Methods: Students (n = 192) in different study years of the dental degree course at the University of Valencia, Spain, analyzed two photographs of a patient in which, by means of computer software, midline diastema, upper and lower midlines, crown length of the maxillary right central incisor, occlusal cant, and “g…
Early clinical outcomes after small incision lenticule extraction surgery (SMILE)
2018
Abstract Purpose Dry eye is known to impact on clinical outcomes after laser vision correction and the use of a newer ‘all femtosecond laser’ surgical approach may be associated with less impact on the ocular surface post-operatively. The purpose of this study was to evaluate the early clinical outcomes and tear instability after the first small incision lenticule extraction (SMILE) cases undertaken by three surgeons at a single site in the UK. Methods Retrospective audit. Seventy-one eyes of 37 patients underwent SMILE surgery using the Zeiss VisuMax laser system (Carl Zeiss Meditec, Germany). Uncorrected and corrected distance visual acuity, spherical equivalent refraction, fluorescein en…
Asymmetric covariance in spot-futures markets
2003
This article studies how the spot-futures conditional covariance matrix responds to positive and negative innovations. The main results of the article are achieved by obtaining the Volatility Impulse Response Function (VIRF) for asymmetric multivariate GARCH structures, extending Lin (1997) findings for symmetric GARCH models. This theoretical result is general and can be applied to analyze covariance dynamics in any financial system. After testing how multivariate GARCH models clean up volatility asymmetries, the Asymmetric VIRF is computed for the Spanish stock index IBEX-35 and its futures contract. The empirical results indicate that the spot-futures variance system is more sensitive to…
The Economic Value of Volatility Transmission Between the Stock and Bond Markets
2008
This study has two main objectives. Firstly, volatility transmission between stocks and bonds in European markets is studied using the two most important financial assets in these fields: the DJ Euro Stoxx 50 index futures contract and the Euro Bund futures contract. Secondly, a trading rule for the major European futures contracts is designed. This rule can be applied to different markets and assets to analyze the economic significance of volatility spillovers observed between them. The results indicate that volatility spillovers take place in both directions and that the stock-bond trading rule offers very profitable returns after transaction costs. These results have important implicatio…
THE STOCHASTIC VOLATILITY MODEL OF BARNDORFF-NIELSEN AND SHEPHARD IN COMMODITY MARKETS
2010
We consider the non-Gaussian stochastic volatility model of Barndorff-Nielsen and Shephard for the exponential mean-reversion model of Schwartz proposed for commodity spot prices. We analyze the properties of the stochastic dynamics, and show in particular that the log-spot prices possess a stationary distribution defined as a normal variance-mixture model. Furthermore, the stochastic volatility model allows for explicit forward prices, which may produce a hump structure inherited from the mean-reversion of the stochastic volatility. Although the spot price dynamics has continuous paths, the forward prices will have a jump dynamics, where jumps occur according to changes in the volatility p…
Volatility co-movements: a time-scale decomposition analysis
2015
In this paper, we are interested in detecting contagion from US to European stock market volatilities in the period immediately after the Lehman Brothers collapse. The analysis is based on a factor decomposition of the covariance matrix, in the time and frequency domain, using wavelets. The analysis aims to disentangle two components of volatility contagion (anticipated and unanticipated by the market). Once we focus on standardized factor loadings, the results show no evidence of contagion (from the US) in market expectations (coming from implied volatility) and evidence of unanticipated contagion (coming from the volatility risk premium) for almost any European country. Finally, the estim…
Trading with Asymmetric Volatility Spillovers
2007
: We study the profitability of trading strategies based on volatility spillovers between large and small firms. By using the Volatility Impulse-Response Function of Lin (1997) and its extensions, we detect that any volatility shock coming from small companies is important to large companies, but the reverse is only true for negative shocks coming from large firms. To exploit these asymmetric patterns in volatility, different trading rules are designed based on the inverse relationship existing between expected return and volatility. We find that most strategies generate excess after-transaction cost profits, especially after very bad news and very good news coming from large or small firm…
Stock Return Volatility on Scandinavian Stock Markets and the Banking Industry: Evidence from the Years of Financial Liberalisation and Banking Crisis
1999
This paper investigates the evolution of the (conditional) volatility of returns on three Scandinavian markets (Finland, Norway and Sweden) over the turbulent period of the past decade, namely the overlapping periods of financial liberalisation, drastically changing macroeconomic conditions and banking crisis. We find that even over this relatively turbulent period volatility is in most cases successfully captured by past volatility and shocks to past volatility, ie by a (symmetric) GARCH process. In each country banking crisis has induced regime shifts in (unconditional) volatility. We also find evidence for cross-country volatility spillovers during the banking crisis episodes. The estima…