Smile Effect Research Articles

The SMILE Effect in the Beam Propagation Direction Affects the Beam Shaping of a Semiconductor Laser Bar Array

Near-field bending of a laser diode bar (i.e., the SMILE effect) degrades the laser beam brightness, adversely affecting optical coupling and beam shaping. Previous reports mainly focused on the two-dimensional near-field bending of a laser diode bar. However, the near-field bending of a laser diode bar not only occurs in the laser bar growth direction, but also in the beam propagation direction. The present article proposes the three-dimensional near-field bending of a laser diode array, which is commonly known as the three-dimensional spatial SMILE effect. Through theoretical and simulated investigations, it has been found that a laser bar array not only deforms in the fast axis direction to cause the traditional two-dimensional SMILE effect but also experiences an additional deformation of approximately 2 μm in the laser emission direction simultaneously. Due to the SMILE effect in the beam propagation direction, not all emitters are aligned in a straight line, and some emitters experience defocusing during collimation. Consequently, there is an increase in the residual divergence angle and beam width, resulting in a degradation of the laser bar array’s beam quality. According to the theoretical calculations, ZEMAX simulations, and experimental results, for a FAC (fast axis collimation) with a focal length of 300 μm, the divergence angle of single emitter after collimating in the fast axis increases from 4.95 mrad to 6.46 mrad when the offsetting of the working distance between the incident beam waist and FAC lens increases from 0 μm to 2 μm.

De-Striping and De-Smiling of Aerial Hyperspectral Image for Water Color Analysis

Hyperspectral imagery is typically acquired in push-broom mechanism, which is prone to image artifacts such as striping and smile for the sensor array whose sensor elements are not perfectly calibrated. The best practice would be to calibrate the sensor elements before the flight, but post-correction is required when images are already acquired without calibration. While there are some studies that addressed those striping and smile effects for hyperspectral images acquired from satellite or aircraft platforms, few studies were done for hyperspectral images that are focusing water color analysis, where the radiance level is approximately only a tenth of terrestrial scenes. This study proposes a correction method specialized for water scenes that also may contain terrestrial objects together, and analyzes the results using real drone-borne hyperspectral imagery taken for an island area in Korea. The result revealed that the variation in columnar mean before the de-striping, which ranges 5-15%, reduced to under 2% after the correction, also exhibiting successful removal of striping in visual inspection. The smile effect that ranges approximately 1-2 mW/m2/nm/sr, which accounts for 30% of radiance from water area, also reduced to under 0.1 mW/m2/nm/sr after the smile correction.

Spectral analysis of beam-combining-systems based on laser array with smile effect

The smile effect in semiconductor laser arrays can cause spectral deterioration in spectral beam combining (SBC) systems. We analyze this effect using position error and pointing deviation and propose a coupled-cavity resonance model based on the external-cavity optical feedback and the multibeam interference theory to study locked spectra. Our results indicate that the central emitter exhibits excellent spectral purity, and the edge emitters show side peaks and a decrease in peak intensity. With the increase in the position error and pointing deviation, the emitters experience an obvious spectral shift and an expansion of the spectral width. Pointing deviation has a greater impact on wavelength locking and array spectral width than position errors. Increasing the focal length and incident angle can reduce shifts and spectral width. Furthermore, adopting a grating with a large line density can also decrease its center wavelength shift and compress the spectral width of the combined beam.

Prospects for hormonal contraception in patients with breast diseases: the Mona Lisa smile effect. A review

Breast diseases (BD) are among the most urgent issues of modern reproductive medicine. This organ is an integral part of the female reproductive system and undergoes cyclic changes during the menstrual cycle. The modern "nosological trio" of BD is mastodynia, benign dysplasia, and breast cancer. These diseases have an extremely high prevalence, and breast cancer, in turn, ranks 1st in the structure of mortality from malignant neoplasms of the female reproductive system. All these aspects warrant the research of the key pathogenetic mechanisms of these conditions. However, one of the most relevant topics in modern gynecology is the counseling on the selection of contraceptive methods in these patients. Therefore, it is necessary to address the safety of hormonal contraceptive methods and to analyze innovations in hormonal contraceptives, which may have several protective and risk-reducing properties for BD.

The Psychological Effects of a Perfect Smile on Adults: A Survey

Purpose: To investigate the psychological impact of dental aesthetics, specifically the effect of a perfect smile, on adults.
 Methodology: A random cross-sectional research was conducted on 200 adult patients who attended the dentistry facilities at Riyadh Elm University. To determine patient satisfaction with their overall dental look, an online questionnaire will be used. This cross-sectional research included REU patients and dentistry students. Adults over the age of 18 were all included in the study.
 Findings: On visible teeth numbers majority selected the second option, on the buccal corridor was option 2 and 3 equally, on smile lip line was first while on lower lip touching again was 2 and 3r equally. The majority of them never had any problem because of mouth or teeth in word pronunciations, in the sense of taste. However, the majority have painful aching in the mouth occasionally. The majority of participants never felt embarrassed and irritable because of any teeth problem. The majority of participants never had difficulty in their usual job doing, less satisfy and unable to function because of any teeth problem.
 Unique Contribution to Theory, Policy and Practice: The paper provides unique insights into the psychological impact of a perfect smile on adults, highlighting its role in enhancing self-esteem and quality of life. It suggests that aesthetic dentistry is not just about physical health but also mental well-being. These findings can guide policy development and practice in dentistry, emphasizing holistic patient care.

Quality of Vision and Ocular Higher Order Aberrations after SMILE for Myopia and Myopic Astigmatism

Background Previous studies have shown considerable amounts of higher order aberrations following SMILE. In our study we aim at accurately quantifying the higher order aberrations following SMILE in myopia and myopic astigmatism. Objective To detect the effect of SMILE on quality of vision and the incidence of higher order aberrations following SMILE. Patients and Methods This is a prospective study that included 30 eyes of 18 patients presented in the outpatient clinic seeking advice for myopic refractive surgical correction. The study was conducted in accordance with the ethical standards stated by the ethical committee of Ain shams university hospitals with informed consents obtained from all participants. Results On studying the post-operative corneal third order aberrations we detected increase in post-operative vertical and horizontal coma, and spherical aberrations with non-significant change in vertical and horizontal trefoil. According to our study results, SMILE is an effective refractive surgery that improves visual acuity. That causes decrease in quality of vision through modulation transfer ratio and increase in ocular higher order aberrations. Conclusion SMILE (small incision lenticule extraction) is an efficient modality for refractive surgical correction of myopia and myopic astigmatism, with significant post-operative improvement in unaided visual acuity detected post-operative increase in the ocular HOAs. Total coma, trefoil and sphere increase significantly in mesopic more than photopic pupil. The degree of myopia didn’t affect the ocular higher order aberrations except for modulation transfer ratio.

Effect of smile on facial attractiveness before and after orthodontic treatment in females with more attractive and less attractive facial background

One of the goals of orthodontic treatment is to improve facial esthetics. This study aimed to determine the effect of smile on facial attractiveness before and after orthodontic treatment in females with "more attractive" and "less attractive" facial backgrounds. In addition, changes in facial attractiveness after orthodontic treatment were examined. Frontal rest and smile photographs of 60 female patients (mean age, 26.32 years) before and after orthodontic treatment were included in 4 separate online questionnaires. The link for each questionnaire was sent to 40 layperson raters (20 females, 20 males). They were asked to give a score from 0 to 100 on the basis of the visual analog scale for the attractiveness of each image. Then the data were collected and analyzed. The mean score of the pretreatment smile was significantly smaller than the frontal rest view, and the difference was significantly greater in the "more attractive" group (P= 0.012). After treatment, the smiling view was significantly more attractive than the frontal rest view, and the difference was significantly greater in the "less attractive" group (P= 0.014). In addition, the attractiveness of both smiling and rest views increased significantly after orthodontic treatment, and these changes were significantly greater in the "more attractive" group (P<0.001 and P= 0.011). An unesthetic pretreatment smile negatively impacted facial attractiveness, and orthodontic treatment significantly improved facial attractiveness. These negative and positive effects were greater in more attractive facial backgrounds.

Effect of the gummy smile on facial attractiveness

A gummy smile is considered a disorder which will lead to immoderate gingival display, and most people are esthetically unaccepted. Many etiologies are linked to a gummy smile, including immoderate maxillary development, delayed passive eruption of teeth, over eruption of teeth, and hyperactive muscles of the upper lip. Various management strategies are present for corrections of gummy smiles. The dentist should decide which is better based on the etiology of the condition and the need of the patient.

Empirical analysis of rough and classical stochastic volatility models to the SPX and VIX markets

We conduct an empirical analysis of rough and classical stochastic volatility models to the SPX and VIX options markets. Our analysis focusses primarily on calibration quality and is split in two parts. In part one, we perform a historical calibration to SPX options over the years 2004–2019 of a selection of models that include the one-factor rough Bergomi and rough Heston models. In part two, we consider three calibration dates with low, typical, and high volatility, examine a wide selection of models, and calibrate to both SPX options as well as jointly to SPX and VIX options. The key results are as follows: The rough Bergomi and rough Heston models fail to create a term structure of smile effect that is sufficiently pronounced for SPX options. Moreover, we discover that short-expiry SPX smiles generally are more symmetric than long-expiry smiles, a feature we neither find that these models can reproduce. We propose an alternative volatility model driven by two Ornstein-Uhlenbeck processes that uses a non-standard transformation function. Calibrating it to SPX options, we obtain almost perfect fits, and calibrating it jointly to SPX and VIX options, we obtain very decent fits. This suggests, contrary to what one might be led to believe based on much of the existing literature, that the joint SPX-VIX calibration problem is largely solvable with classical two-factor volatility, all without roughness and jumps.

Impact of severity of malocclusion and self-perceived smile and dental aesthetics on self-esteem among adolescents

The psychological impact of malocclusion, social acceptance, self-esteem, and the development of personality traits are considerations that can affect the demand for orthodontic treatment. The aim of this study was to assess the effect of malocclusion severity and self-perceived smile and dental aesthetics on self-esteem among adolescents in Lagos, Nigeria. This analytical cross-sectional study was performed among 393 adolescents (210 females and 183 males) at a university teaching hospital in Nigeria. The need for orthodontic treatment was assessed using the Dental Aesthetic Index, whereas self-esteem was measured using the Rosenberg Self-Esteem Scale. Smile analysis was performed on photographs of posed smiles, whereas photographs of posed smiles and intraoral frontal view with teeth in centric occlusion were rated with the Visual Analog Scale for self-perception of smile and dental aesthetics. A comparison of variables among self-esteem groups was made using the ANOVA and Tukey post hoc tests, whereas an association among all variables was examined using the correlation coefficient. Stepwise regression analysis examined the effects of independent variables on self-esteem. A significant correlation was found between self-esteem and self-perceived smile (r=0.294; P < 0.001) and dental aesthetics (r=0.212; P < 0.001). Adolescents with high self-perceived smile (mean ± standard deviation, 7.66 ± 2.20) and dental aesthetics (6.68 ± 2.58) had higher self-esteem than participants with low self-perceived smile (4.75 ± 2.73) and dental aesthetics (4.36 ± 2.29). Self-perceived smile aesthetics had the most predictive impact on self-esteem. The results showed that self-perception of smile and dental aesthetics is a significant factor that influences self-esteem among adolescents.

High‐throughput and High‐speed Absorbance Measurements in Microfluidic Droplets using Hyperspectral Imaging

AbstractThe recent progress of machine learning and microfluidics in the chemical and biological sciences has motivated the development of new online techniques to interrogate the (bio)chemical contents within moving droplets. To accelerate the optical characterization of new materials and chemical reactions, we combine a line‐scan hyperspectral imaging system with a droplet‐based microfluidic reactor. We demonstrate the performance of this platform on a model chemistry – silver nanoparticle synthesis. The platform can image the spectral signature of ∼400 individual droplets in only 15 s, with droplet flow speeds exceeding 4 cm/s in the reaction tube. After correction of the keystone and smile effects on the hyperspectral images, the absorbance spectra are extracted from the droplets with an accuracy comparable to industrial spectrophotometers. The time evolution of the UV/Vis absorbance spectra during the reactive synthesis can be tracked either by scanning all the droplets present in the reaction tube or by following a subset of the droplet ensemble at frame rates up to 92 fps. This high‐throughput and high‐speed platform is particularly interesting for screening large parameter spaces and imaging fast reactions with a high resolution, for eventual coupling with advanced machine learning techniques to infer kinetic models and obtain detailed mechanistic insights.

Tempered stable processes with time-varying exponential tails

In this paper, we introduce a new time series model with a stochastic exponential tail. This model is constructed based on the Normal Tempered Stable distribution with a time-varying parameter. It captures the stochastic exponential tail, which generates the volatility smile effect and volatility term structure in option pricing. Moreover, the model describes the time-varying volatility of volatility and empirically indicates stochastic skewness and stochastic kurtosis in the S&P 500 index return data. We present a Monte-Carlo simulation technique for parameter calibration of the model for S&P 500 option prices and show that a stochastic exponential tail improves the calibration performance.

Study on bonding of single bar high power semiconductor lasers

Due to the mismatch between the thermal expansion coefficients of semiconductor laser chip and heat sink, giant thermal stresses will be generated after eutectic bonding. Immoderate thermal stress will cause the devices to produce the smile effect, making the coupling efficiency low. In this paper, we propose an approach to reduce thermal stress and improve the near-field linearity for semiconductor laser arrays. We optimize the eutectic bonding process by controlling the semiconductor laser chip and heat sink in different temperature fields through independent heat sources, to achieve the purpose of matching the shape variables earlier than welding. The heating temperature is determined by Suhir’s deformation formula (Suhir E. Stresses in Bi-metal thermostats. J Appl Mech. 1986;53(3):657–660; Suhir E. Stresses in adhesively bonded Bi-material assemblies used in electronic packaging. MRS Proc. 1986;72). Then, finite element Analysis (FEA) was used for simulation verification.

The face is the index of the mind: understanding the association between self-construal and facial expressions

PurposeThis study aims to examine the relationship between consumers’ emotional expressions and their self-construals. The authors suggest that because an independent self-construal can reinforce the free expression of emotion, the expression of extreme emotions is likely to become associated with feelings of independence through social learning.Design/methodology/approachThe paper includes five studies. Study 1A provided evidence that priming participants with different types of self-construal can influence the extremity of their emotional expressions. Study 1B showed that chronic self-construal could predict facial expressions of students who were told to smile for a group photograph. Studies 2–4 found that inducing people to either manifest or to simply view an extreme facial expression activated an independent social orientation and influenced their performance on tasks that reflect this orientation.FindingsThe studies provide support for a bidirectional causal relationship between individuals’ self-construals and the extremity of their emotional expressions. They show that people’s general social orientation could predict the spontaneous facial expressions that they manifest in their daily lives.Research limitations/implicationsAlthough this research was generally restricted to the effects of smiling, similar considerations influence the expression of other emotions. That is, dispositions to exhibit extreme expressions can generalize over different types of emotions. To this extent, expressions of sadness, anger or fear might be similarly associated with people’s social orientation and the behavior that is influenced by it.Practical implicationsThe paper provides marketing implications into how marketers can influence consumers’ choices of unique options and how marketers can assess consumers’ social orientation based on their observation of consumers’ emotional expressions.Originality/valueTo the best of the authors’ knowledge, this research is the first to demonstrate a bidirectional causal relationship between individuals’ self-construals and the extremity of their emotional expressions, and to demonstrate the association between chronic social orientation and emotional expression people spontaneously make in their daily lives.

Improved cloud detection over sea ice and snow during Arctic summer using MERIS data

Abstract. The historic MERIS (Medium Resolution Imaging Spectrometer) sensor on board Envisat (Environmental Satellite, operation 2002–2012) provides valuable remote sensing data for the retrievals of summer sea ice in the Arctic. MERIS data together with the data of recently launched successor OLCI (Ocean and Land Colour Instrument) on board Sentinel 3A and 3B (2016 onwards) can be used to assess the long-term change of the Arctic summer sea ice. An important prerequisite to a high-quality remote sensing dataset is an accurate separation of cloudy and clear pixels to ensure lowest cloud contamination of the resulting product. The presence of 15 visible and near-infrared spectral channels of MERIS allows high-quality retrievals of sea ice albedo and melt pond fraction, but it makes cloud screening a challenge as snow, sea ice and clouds have similar optical features in the available spectral range of 412.5–900 nm. In this paper, we present a new cloud screening method MECOSI (MERIS Cloud Screening Over Sea Ice) for the retrievals of spectral albedo and melt pond fraction (MPF) from MERIS. The method utilizes all 15 MERIS channels, including the oxygen A absorption band. For the latter, a smile effect correction has been developed to ensure high-quality screening throughout the whole swath. A total of 3 years of reference cloud mask from AATSR (Advanced Along-Track Scanning Radiometer) (Istomina et al., 2010) have been used to train the Bayesian cloud screening for the available limited MERIS spectral range. Whiteness and brightness criteria as well as normalized difference thresholds have been used as well. The comparison of the developed cloud mask to the operational AATSR and MODIS (Moderate Resolution Imaging Spectroradiometer) cloud masks shows a considerable improvement in the detection of clouds over snow and sea ice, with about 10 % false clear detections during May–July and less than 5 % false clear detections in the rest of the melting season. This seasonal behavior is expected as the sea ice surface is generally brighter and more challenging for cloud detection in the beginning of the melting season. The effect of the improved cloud screening on the MPF–albedo datasets is demonstrated on both temporal and spatial scales. In the absence of cloud contamination, the time sequence of MPFs displays a greater range of values throughout the whole summer. The daily maps of the MPF now show spatially uniform values without cloud artifacts, which were clearly visible in the previous version of the dataset. The developed cloud screening routine can be applied to address cloud contamination in remote sensing data over sea ice. The resulting cloud mask for the MERIS operating time, as well as the improved MPF–albedo datasets for the Arctic region, is available at https://www.seaice.uni-bremen.de/start/ (Istomina et al., 2017).

The continuous limit of weak GARCH

GARCH models are called ‘strong’ or ‘weak’ depending on the presence of parametric distributional assumptions for the innovations. The symmetric weak GARCH(1, 1) is the only model in the GARCH class that has been proved to be closed under the temporal aggregation property . This property is fundamental in two respects: (a) for a time-series model to be invariant to the data frequency; and (b) for a unique option-pricing model to exist as a continuous-time limit. While the symmetric weak GARCH(1, 1) is temporally aggregating precisely because it makes no parametric distributional assumptions, the lack of these also makes it harder to derive theoretical results. Rising to this challenge, we prove that its continuous-time limit is a geometric mean-reverting stochastic volatility process with diffusion coefficient governed by a time-varying kurtosis of log returns. When log returns are normal the limit coincides with Nelson’s strong GARCH(1, 1) limit. But unlike strong GARCH models, the weak GARCH(1, 1) has a unique limit because it makes no assumptions about the convergence of model parameters. The convergence of each parameter is uniquely determined by the temporal aggregation property. Empirical results show that the additional time-varying kurtosis parameter enhances both term-structure and smile effects in implied volatilities, thereby affording greater flexibility for the weak GARCH limit to fit real-world data from option prices.

Fundraising through the F2F: When the smile implies a rejection of the interaction

The objective of this study is to explore the effect of the intentional smile on social rejection in the F2F communication strategy of NGOs. Two studies analyze the effect of smiling on passerby conduct, as well as related influence mechanisms. First, 1,298 passersby were approached by two fundraisers, one male and one female; in half of their attempts to engage the passersby, the fundraisers approached with a friendly smile, whereas in the other half, they did not smile. Data were collected on the frequency of rejections and acceptances of contact with the fundraiser. Second, 1,157 approaches were made to analyze the effect of smiling on types of rejection. Results suggest that the likelihood of the interaction being accepted is greater with a smiling than a non‐smiling approach. Hostile rejections appear to be an effect of the positive impression smiling gives in a self‐interested setting. Practical and theoretical implications are discussed.

Influence of smile effect on beam properties of spectrally combined beams based on diode laser stacks

The smile effect is inevitable during the packaging process of diode laser stacks. Position errors and direction errors are used to describe the smile effect. A theoretical smile model has been built, and a beam propagation model of the external cavity has been further proposed based on the smile model. Beam properties such as spectrum, intensity distribution, and beam quality of combined beams have been simulated and discussed. The results show that position errors have little impact on intensity distribution of combined beams but make spectrum slightly broadened. Direction errors make intensity generate side lobes and degrade beam quality significantly. Compared with position errors, direction errors in both slow axis and fast axis have more detrimental effect on output beams. Thus, it is more important to control angle deflection of beams than positions of emitters during the manufacturing process of DLSs.

Method to control near-field bowing of laser diode arrays by balancing the thermal-induced stress

Due to the thermal-induced stress during the bonding process, the emitters in a laser diode array (LDA) are vertically displaced, which causes the near-field bowing of a laser diode bar (i.e., the SMILE effect). Near-field bowing degrades the laser beam brightness, adversely affecting optical coupling and beam shaping, resulting in a larger divergence angle and a wider line after focusing and collimation. The mechanism of near-field bowing has been theoretically studied, in which the ratio of tensile strength between submount and heat sink has a great effect on the deformation of LDAs. Arm-wrestling between CuW submount and heat sink vividly describes that the deformation of LDAs changes as a function of the ratio of two materials’ tensile strength. We design a symmetrical structure that bonds another submount on the bottom of the heat sink to control the SMILE effect by balancing the acting force from the top of the heat sink. The deformation of the heat sink and LDAs are approximately zero when the thermal-induced stresses forced on the top and bottom of the heat sink are equal.

Smiling and use of first-name by a healthcare receptionist robot: Effects on user perceptions, attitudes, and behaviours

AbstractRobots are now starting to be developed and used as receptionists in health applications. In this regard, it is important that robots’ behavioural skills are developed and researched so that people have appropriate and comfortable interactions. Smiling and use of first name are two more important social communication skills used during human interactions. While smiling and use of first name are often employed by robots in human interactions, the effect of these behaviours on perceptions of receptionist robots has not yet been experimentally investigated. This study explored the effects of robot smiling and robot use of the participant’s first name on perceptions of robot friendliness, mind, and personality, as well as attitudes and smiling behaviour. Forty participants interacted with a medical receptionist robot four times, in a two by two repeated measures design. Both smiling and use of first name had significant positive effects on participants’ perceptions of robot personality. Robot smiling also showed significant effects on participants’ overall attitudes towards robots, ratings of robot friendliness, and perceptions of the robot’s mind, and increased the frequency of participants’ own smiling. There were no significant interaction effects. Robot smiling in particular can enhance user perceptions of robots and increase reciprocal smiling.