Stocks with large increases in call (put) implied volatilities over the previous month tend to have high (low) future returns. Sorting stocks ranked into decile portfolios by past call implied ...volatilities produces spreads in average returns of approximately 1% per month, and the return differences persist up to six months. The cross section of stock returns also predicts option implied volatilities, with stocks with high past returns tending to have call and put option contracts that exhibit increases in implied volatility over the next month, but with decreasing realized volatility. These predictability patterns are consistent with rational models of informed trading.
We study a dynamic voluntary disclosure setting where the manager’s information and the firm’s value evolve over time. The manager is not limited in her disclosure opportunities, but disclosure is ...costly. The results show that the manager discloses even if this leads to a price decrease in the current period. The manager absorbs this price drop in order to increase her option value of withholding disclosure in the future. That is, by disclosing today, the manager can improve her continuation value. The results provide a number of novel empirical predictions regarding asset prices and disclosure patterns over time. These include, among others, that disclosures are negatively correlated in time, and stock return skewness is negatively correlated with lagged returns for firms with low uncertainty over their future profitability, in more competitive industries, and in industries with less informative public news.
•Knowledge gain through online laboratory safety education is ineffective.•Attitude toward online education is the strongest predictor of intention to use.•Student preferences in an e-learning ...environment should be interpreted carefully.•Lack of motivation for learning in the online environment should be resolved.
Safety education is essential to prevent accidents and casualties in modern society. The coronavirus disease (COVID-19) pandemic has increased the importance of e-learning in safety education. However, there is limited research on the effectiveness of this type of education. This study aims to develop a model that predicts the factors affecting the learning outcomes of safety education in an e-learning environment. An online survey of research workers who participated in laboratory safety education at a university was conducted to empirically test the developed model. Partial least squares-based structural equation modeling (PLS-SEM) was used for analysis and hypothesis testing. Face-to-face interviews were conducted to supplement the findings. The results revealed the following. (1) Intention to use online laboratory safety education (OLSE) was significantly and positively predicted by attitude toward online education and satisfaction, but not by attitude toward safety education. (2) Respondents preferred safety education through e-learning not because of its effectiveness, but to avoid the stress and inconvenience of traditional training. (3) Negative perceptions of education and lack of motivation to learn are the root causes of low effectiveness. The findings revealed the current status of OLSE with deficient learning effects and learners' negative perceptions. This study identifies the adverse effects of mandatory safety education in e-learning environments. This study provides insights into the low effectiveness of mandated online safety education and argues for the need to increase learner motivation and improve legislation. We suggest several practical implications to improve the effectiveness of such education.
Facilitating anti-reflection has been of great scientific and practical interest due to its diverse applications in optical devices including solar cells and photodetectors. Various anti-reflection ...schemes are exploited and elaborated to realize effective broadband suppression of reflected light. In this work, we present and analyze a metasurface coating on silicon for efficient anti-reflection by leveraging the design rules of the Chebyshev transformer in the field of transmission line theory in the microwave regime. We explore the underlying physics of the metasurface by comparing the two representative types of constituent nanostructures and evaluating their optical properties using effective index retrieval methods. In particular, by designing nanostructures with subtle vertical etching in the pyramid valley, a broadband anti-reflection coating ranging from 400 to 1100 nm is achieved with reflection of less than 3%. We believe that the proposed design rule and analysis for this Chebyshev metasurface could pave an important way to realize systematic and effective anti-reflection schemes for diverse optical devices.
Zusammenfassung
Hintergrund und Zielsetzungen
Die konventionellen Therapieoptionen zur Reduktion von infraorbitalen Fett depots (gemeinhin auch als Tränensäcke bezeichnet) sind im Allgemeinen auf ...chirurgische Verfahren beschränkt. In letzter Zeit wurden jedoch zahlreiche Versuche unternommen, um diesem Schönheitsfehler mit nichtchirurgischen Interventionen zu begegnen. Ziel dieser Studie war es, die Wirksamkeit und Sicherheit eines Radiofrequenzsystems mit isolierten Mikronadeln zur Behandlung von infraorbitalen Fett depots zu untersuchen.
Methoden
Dies ist eine monozentrische Studie mit Vorher‐Nachher‐Vergleich. Zweiundzwanzig Probanden mit infraorbitalen Fettansammlungen wurden mit einem micro‐insulated needle radiofrequency system zweimal in einem Abstand von vier Wochen behandelt. Bei jeder Sitzung wurden nacheinander zwei Nadelaufsätze mit teilisolierten Nadeln unterschiedlicher Länge eingesetzt. Mit einem dreidimensionalen Photogrammetrie‐System wurden die Veränderungen der infraorbitalen Fettpolster objektiv vermessen. Das Ergebnis wurde darüber hinaus vom Untersucher mit Hilfe des Investigator Global Assessment (IGA) Scores beurteilt.
Ergebnisse
Das durchschnittliche Ausmaß der Fettpolster hatte sich nach zwölf Wochen signifikant verringert und dieser Zustand blieb bis Woche 24 erhalten. Der IGA‐Score veringerte sich nach vier Wochen signifikant, nahm bis zur Woche 12 weiter ab und blieb anschließend bis zur Woche 24 erhalten. Bis auf Schwellungen und Blutergüsse am Unterlid, die nach etwa einer Woche abgeheilt waren, gab es keine Nebenwirkungen.
Fazit
Die Radiofrequenztherapie mit isolierten Mikronadeln ist eine effektive und nebenwirkungsarme Therapieoption, um infraorbitale Fettdepots zu behandeln.
Digital mucous cysts (DMC) are common benign myxoid cysts typically located on the fingers and toes. Recently, dermoscopic patterns of DMC were reported. However, only a small number of cases were ...described in the published work; therefore, information on this topic is scarce in the published work. We investigated dermoscopic patterns of histopathologically diagnosed DMC. In total, 23 cases were enrolled in this study. Polarized dermoscopy revealed vascular patterns in 13 cases (56.5%), with arborizing vascular patterns, dotted vessels, linear vessels and polymorphous vessels in eight (34.8%), three (13.0%), one (4.3%) and one (4.3%) case, respectively. Red‐purple lacunas, ulceration, nail dystrophy and white shiny structures were detected in five (21.7%), two (8.7%), seven (30.4%) and six cases (26.1%), respectively. We report the largest case series regarding dermoscopic features of DMC to date. Dermoscopy can be used as a helpful adjuvant and non‐invasive tool in the diagnosis of DMC.
Summary
Background and objectives
Conventional treatment options for eyelid fat bulging are generally limited to surgical approaches. However, many attempts have been made recently to manage this ...disfigurement using non‐surgical interventions. The purpose of this study was to evaluate the efficacy and safety of a micro‐insulated needle radiofrequency system for the treatment of lower eyelid fat bulging.
Methods
This is a single center pre‐post comparative study. Twenty‐two subjects with lower eyelid fat bulging were treated twice using the needle radiofrequency system, at an interval of four weeks. Two types of partially insulated needles with different lengths were used in each session. A three‐dimensional photogrammetry system was used to objectively measure changes in the extent of the fat bulge. The investigator's global assessment (IGA) of the severity of fat bulging was also evaluated.
Results
The average extent of fat bulging was decreased significantly after twelve weeks, and was maintained until 24 weeks. The IGA score was significantly decreased after four weeks and further decreased after twelve weeks, and then maintained until 24 weeks. There were no side effects, except for lower eyelid swelling and bruising that lasted for about a week.
Conclusion
The micro‐insulated needle radiofrequency system can be a beneficial and well‐tolerated treatment for lower eyelid fat bulging.
CMOS image sensor (CIS) plays a crucial role in diverse optical applications by facilitating the capture of images in the visible and near-infrared spectra. The enhancement of image resolution in CIS ...by an increase in pixel density is becoming more significant and realizable with the recent progress of nanofabrication. However, as pixel size decreases towards the diffraction limit, there is an inevitable trade-off between the scale-down of pixel size and the enhancement of optical sensitivity. Recently, to overcome this, an entirely new concept of spectral sensing using a nanophotonic-based color router has been proposed. In this work, we present a metasurface-based spectral router to effectively split the spectrum from visible to near-infrared and redirect through the four optical channels to the targeted pixel surfaces. We optimize the metasurface that simultaneously controls the phases of the transmitted light of targeted spectra, i.e. red (R), green (G), blue (B), and near-infrared (NIR), which is the largest number of channels reported based on a single layered metasurface and has an optical efficiency that surpasses the efficiency of conventional color filter systems.
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