Search results for "statistical [methods]"
showing 10 items of 1664 documents
Establishing a diagnostic tool for assessing optimal treatment timing in Indian children with developing malocclusions
2011
Objective: To interrelate chronological age, cervical vertebrae maturational stage and dental calcification stages and to establish latter as first level diagnostic tool to estimate timing of pubertal growth spurt. Materials and Methods: Sample derived from pretreatment panaromic and lateral cephalometric radiographs of patients 8-14 years old. Study sample divided into three groups depending upon Angle’s molar relation: Group I, Group II, Group III. According to chronological age, into: Group A: 8-11 years Group B:11-14 years, further separating males and female subjects in each group. Demirjian et al method was used to assess dental maturity and for skeletal maturity the New Improved Vers…
Efficacy of infiltrative local anesthesia and inferior alveolar nerve block in periapical surgery of lower premolars and molars : a preliminary report
2020
Background The aims of this study were: 1) compare the amount of anesthesia used with the anesthetic technique; 2) relate the quantity of anesthesia needed with the level of anxiety of the patient; 3) study the relationship between the anesthetic technique and the level of hemostasis; 4) correlate the amount of anesthesia with patient and tooth dependent variables. Material and Methods A randomized controlled trial was designed with two parallel groups according to the anesthetic technique: infiltrative local anesthesia (infiltrative group) and inferior alveolar nerve block (block group). The following variables were collected: sex, age, smoking habits, plaque index, symptoms, signs, positi…
Age estimation using the radiographic visibility of the periodontal ligament in lower third molars in a Portuguese population.
2014
Objectives: The mineralization of third molars has been used repeatedly as a method of forensic age estimation. However, this procedure is of little use beyond age 18, especially to determinate if an individual is older than 21 years of age; thus, the development of new approaches is essential. The visibility of the periodontal ligament has been suggested for this purpose. The aim of this work was to determine the usefulness of this methodology in a Portuguese population. Study Design: Periodontal ligament visibility was assessed in the lower third molars, using a sample of 487 orthopantomograms, 228 of which belonging to females and 259 to males, from a Portuguese population aged 17 to 31 …
Effect of preemptive dexamethasone and etoricoxib on postoperative period following impacted third molar surgery - a randomized clinical trial.
2019
Background The aim of this study was to compare the anti-inflammatory effects of dexamethasone and etoricoxib after third molar extraction. Material and Methods A prospective, randomized, controlled, split-mouth study was conducted. 19 volunteers were allocated randomly to receive 90mg etoricoxib 1 hour prior to the procedure or 4mg intramuscular dexamethasone immediately after anesthesia. Baseline measurements were obtained preoperatively, and subsequent assessments were made on immediate postoperative, at 72 hours and 7 days after surgery to measure postoperative facial swelling by use of linear measurements, interincisal mouth opening width and visual analog scale score for pain. The amo…
Return Dispersion and Cross-Sectional Asset Pricing Anomalies
2015
Recent research finds that cross-sectional return dispersion provides a risk-based explanation for some investment anomalies, including accrual, investment, and momentum strategies. This study extends the analyses of return dispersion to a broad set of anomalies by testing whether the state of return dispersion is associated with anomalous returns. Empirical results for 12 well-known anomalies indicate a robust link between good and bad states of return dispersion and most anomalies. Also, return dispersion helps to explain a number anomalies regardless of their association with investor sentiment. We conclude that market risk related to return dispersion plays an important role in many inv…
Risk-Managed 52-Week High Industry Momentum, Momentum Crashes, and Hedging Macroeconomic Risk
2017
This is the first study that investigates the profitability of Barroso and Santa-Clara’s (2015) risk managing approach for George and Hwang’s (2004) 52-week high momentum strategy in an industrial portfolio setting. The findings indicate that risk-managing adds value as the Sharpe ratio increases, and the downside risk remarkably decreases. Even after controlling for the spread of the traditional 52-week high industry momentum strategy in association with standard risk-factors, the risk-managed version generates economically and statistically significant payoffs. Notably, the risk-managed strategy is partially explained by changes in cross-sectional return dispersion, whereas the traditiona…
Liquid methane at extreme temperature and pressure: Implications for models of Uranus and Neptune
2012
We present large scale electronic structure based molecular dynamics simulations of liquid methane at planetary conditions. In particular, we address the controversy of whether or not the interior of Uranus and Neptune consists of diamond. In our simulations we find no evidence for the formation of diamond, but rather sp2-bonded polymeric carbon. Furthermore, we predict that at high tem- perature hydrogen may exist in its monoatomic and metallic state. The implications of our finding for the planetary models of Uranus and Neptune are in detail discussed.
Ion-ion correlation and charge reversal at titrating solid interfaces
2009
Confronting grand canonical titration Monte Carlo simulations (MC) with recently published titration and charge reversal (CR) experiments on silica surfaces by Dove et al. and van der Heyden it et al, we show that ion-ion correlations quantitatively explain why divalent counterions strongly promote surface charge which, in turn, eventually causes a charge reversal (CR). Titration and CR results from simulations and experiments are in excellent agreement without any fitting parameters. This is the first unambiguous evidence that ion-ion correlations are instrumental in the creation of highly charged surfaces and responsible for their CR. Finally, we show that charge correlations result in "a…
Color Difference Thresholds in Dentistry
2015
Purpose The aim of this prospective multicenter study was to determine 50:50% perceptibility threshold (PT) and 50:50% acceptability threshold (AT) of dental ceramic under simulated clinical settings. Materials and Methods The spectral radiance of 63 monochromatic ceramic specimens was determined using a non-contact spectroradiometer. A total of 60 specimen pairs, divided into 3 sets of 20 specimen pairs (medium to light shades, medium to dark shades, and dark shades), were selected for psychophysical experiment. The coordinating center and seven research sites obtained the Institutional Review Board (IRB) approvals prior the beginning of the experiment. Each research site had 25 observers,…
Clustering ball possession duration according to players’ role in football small-sided games
2022
This study aimed to explore which offensive variables best discriminate the ball possession duration according to players specific role (defenders, midfielders, attackers) during a Gk+3vs3+Gk football small-sided games. Fifteen under-15 players (age 13.2±1.0 years, playing experience 4.2±1.0 years) were grouped according to their positions (team of defenders, n = 5; team of midfielders, n = 7; team of attackers, n = 3). On each testing day (n = 3), each team performed one bout of 5-min against each team in a random order, accounting for a total of nine bouts in the following scenarios: i) defenders vs midfielders; ii) defenders vs attackers; iii) midfielders vs attackers. Based on video, a …