Discomfort luminance level of head-mounted displays depending on the adapting luminance

The Images in an immersive head-mounted display (HMD) for virtual reality provide the sole source for visual adaptation. Thus, significant, near-instantaneous increases in luminance while viewing an HMD can result in visual discomfort. Therefore, the current study investigated the luminance change necessary to induce this discomfort. Based on the psychophysical experiment data collected from 10 subjects, a prediction model was derived using four complex images and one neutral image, with four to six levels of average scene luminance. Result showed that maximum area luminance has a significant correlation with the discomfort luminance level than average, median, or maximum pixel luminance. According to the prediction model, the discomfort luminance level of a head-mounted display was represented as a positive linear function in log(10) units using the previous adaptation luminance when luminance is calculated as maximum area luminance

The Association Between Willingness of Frontline Care Providers’ to Adaptively Use of Telehealth Technology and Virtual Service Performance in Provider-to-Provider Communication: Quantitative Study

Background: Telehealth technology can create a disruptive communication environment for frontline care providers who mediate virtual communication with specialists in electronic consultations. As providers are dealing with various technology features when communicating with specialists, their flexible attitude and behaviors to use various telehealth-related technology features can change the outcome of virtual care service. Objective: The objective of this study is to examine frontline care providers’ technology adaptation behaviors in the electronic consultation context. From the perspective of frontline care providers, we reapply and retest a theoretical model, reflecting a mechanism through which technology users’ personal characteristics and technology adaptation behavior enhance virtual service performance, which is an important performance enabler in this online meeting context. In provider-to-provider communication, particularly, we explore the association among providers’ information technology (IT)–related personal characteristics, adaptive telehealth technology use, and virtual service performance. Methods: An online survey was administered to collect individual providers’ personal traits, IT adaptation, and perception on virtual service performance. Partial least squares-structural equation modeling was used to estimate our predictive model of personal traits—IT adaptation, such as exploitative use (use the telehealth technology in a standard way), and exploratory use (use the telehealth technology as innovative way)—and virtual service performance. Results: We collected 147 responses from graduate nursing students who were training to be nurse practitioners in their master’s program, resulting in 121 valid responses from the cross-section online survey. Our theoretical model explained 60.0% of the variance in exploitative use of telehealth technology, 44% of the variance in exploratory use of telehealth technology, and 66% of the variance in virtual service performance. We found that exploitative IT use is an important driver to increase virtual service performance (β=0.762, P\u3c.001), and personal characteristics such as habit are positively associated with both exploitative (β=0.293, P=.008) and exploratory use behaviors (β=0.414, P=.006), while computer self-efficacy is positively associated with exploitative use of telehealth technology (β=0.311, P=.047). Conclusions: This study discusses the unique role of frontline care providers in a virtual care service context and highlights the importance of their telehealth adaptation behavior in provider-to-provider communication. We showed that providers perceive that telehealth technologies should function as intended, otherwise it may create frustration or avoidance of the telehealth technology. Moreover, providers’ habitual use of various technologies in daily lives also motivates them to adaptively use telehealth technology for improving virtual care service. Understanding providers’ technology habit and adaptation can inform health care policy and further provide a better view of the design of telehealth technology for online communication

Perceptual difference between the discomfort luminance level and the brightness of a head-mounted display (HMD)

A psychophysical experiment was conducted to compare the discomfort luminance level and the brightness of a head-mounted display (HMD). The results showed that as the size of the HMD stimulus increased, both the discomfort luminance level of the HMD and the brightness of the HMD decreased, but the influence of the size change was more dramatic on the discomfort luminance level than on the brightness. This study showed that to provide a comfortable luminance level for HMDs, the adaptation luminance level and the size of the HMD stimulus should be considered. However, it cannot be predicted in terms of brightness

A hydro/oxo-phobic top hole-selective layer for efficient and stable colloidal quantum dot solar cells

In this report, we explore the underlying mechanisms by which doped organic thin films as a top hole-selective layer (HSL) improve the performance and stability of colloidal quantum dot (CQD)-based solar cells. Molecular dynamics-based theoretical studies prove that the hydro/oxo-phobic properties of the HSL serve to efficiently passivate the CQD solid. Furthermore, the robust and outstanding electrical properties of the HSL, simultaneously ensure a high power conversion efficiency (PCE) and increase the stability performance of CQD-based solar cells. As a result, a best PCE of 11.7% in a lead sulfide (PbS)-based CQD solar cell is achieved and over 90% of the initial performance is retained after 1 year storage under ambient conditions

A hydro/oxo-phobic top hole-selective layer for efficient and stable colloidal quantum dot solar cells

In this report, we explore the underlying mechanisms by which doped organic thin films as a top hole-selective layer (HSL) improve the performance and stability of colloidal quantum dot (CQD)-based solar cells. Molecular dynamics-based theoretical studies prove that the hydro/oxo-phobic properties of the HSL serve to efficiently passivate the CQD solid. Furthermore, the robust and outstanding electrical properties of the HSL, simultaneously ensure a high power conversion efficiency (PCE) and increase the stability performance of CQD-based solar cells. As a result, a best PCE of 11.7% in a lead sulfide (PbS)-based CQD solar cell is achieved and over 90% of the initial performance is retained after 1 year storage under ambient conditions

Comparison of serum protein profiles between major depressive disorder and bipolar disorder

Major depressive disorder and bipolar disorder are prevalent and debilitating psychiatric disorders that are difficult to distinguish, as their diagnosis is based on behavioural observations and subjective symptoms. Quantitative protein profile analysis might help to objectively distinguish between these disorders and increase our understanding of their pathophysiology. Thus, this study was conducted to compare the peripheral protein profiles between the two disorders. Serum samples were collected from 18 subjects with major depressive disorder and 15 subjects with bipolar disorder. After depleting abundant proteins, liquid chromatography-tandem mass spectrometry (LC-MS/MS) and label-free quantification were performed. Data-dependent acquisition data were statistically analysed from the samples of 15 subjects with major depressive disorder and 10 subjects with bipolar disorder who were psychotropic drug-free. Two-sided t-tests were performed for pairwise comparisons of proteomes to detect differentially-expressed proteins (DEPs). Ingenuity Pathway Analysis of canonical pathways, disease and functions, and protein networks based on these DEPs was further conducted. Fourteen DEPs were significant between subjects with major depressive disorder and those with bipolar disorder. Ras-related protein Rab-7a (t = 5.975, p= 4.3 × 10− 6) and Rho-associated protein kinase 2 (t = 4.782, p= 8.0 × 10− 5) were significantly overexpressed in subjects with major depressive disorder and Exportin-7 (t = -4.520, p= 1.5 × 10− 4) was significantly overexpressed in subjects with bipolar disorder after considering multiple comparisons. Bioinformatics analysis showed that cellular functions and inflammation/immune pathways were significantly different. Ras-related protein Rab-7a, Rho-associated protein kinase 2, and Exportin-7 were identified as potential peripheral protein candidates to distinguish major depressive disorder and bipolar disorder. Further large sample studies with longitudinal designs and validation processes are warranted.This study was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI17C0870), and a grant from the Ministry of Science, ICT, and Future Planning, Republic of Korea (grant number: NRF-2019M3C7A1030625). The funding body had no involvement in study design planning, data collection, analysis, interpretation of data in writing the manuscript

Color Appearance and Discomfort Luminance Level of Head-Mounted Displays (HMDs)

Department of Biomedical Engineering (Human Factors Engineering)In this study, the color appearance and discomfort luminance level of head-mounted displays (HMDs) were investigated. The perceived color appearance of displays differs depending on the ambient light, the size of the stimulus, and the adaptation time, even if the displays physically reproduce the same luminance and chromaticity. In the case of an HMD, it completely blocks ambient light and provides a large screen, allowing users to immerse themselves in a virtual environment. However, due to these characteristics, the brightness and colorfulness of an HMD is different with that of a monitor which is used under the ambient light. Therefore, it is necessary to study how the color appearance of the HMD differs from that of the monitor and whether the color appearance of the HMD can be predicted well with the existing color appearance model. In addition, to set a proper luminance that does not cause discomfort for the user, a study on the discomfort luminance level (i.e., the minimum luminance levels that cause discomfort owing to the high brightness) of HMDs is needed. 1) Color Appearance of HMD In this study, psychophysical experiments were conducted to determine the color appearance of an HMD by comparing the brightness and colorfulness of the stimulus on an HMD with that on an LCD in a dark room. As a result, it is confirmed that even if an HMD and LCD show the physically same luminance and chromaticity, the HMD is brighter and more colorful than the LCD. As an evaluation of existing color appearance models, it is confirmed that the existing color appearance model has limitations in predicting the brightness and colorfulness of the HMD due to the characteristic of blocking ambient light and providing a large screen. Based on these experimental results, a new way to predict brightness and colorfulness of HMDs was proposed. 2) Discomfort Luminance Level of HMD In this study, a total of five psychophysical experiments were conducted to investigate the discomfort luminance level of an HMD according to the adaptive luminance of the previous scene or illuminance of initial ambient light. As a result of the experiment, it was confirmed that the lower the illuminance of the adaptive initial ambient light or the luminance of the previous adaptive image, the lower the discomfort luminance of the HMD. In addition, in the case of complex images, it is confirmed that the maximum luminance of an image that passed the low pass filter can minimize the deviation between image types. Based on this, the author proposes a model that can predict the discomfort luminance of HMDs by using an power function. The proposed model can be used as a criterion for setting the optimal HMD luminance. Thus, the prediction model contributes to the development of user-centered HMDs based on the visual adaptation and provides energy efficient HMDs to control the proper luminance which does not cause discomfort but maintains the image quality.ope

Prediction model for discomfort luminance levels of head-mounted displays

To predict the luminance threshold of head-mounted displays (HMDs), which can cause discomfort due to excessive brightness, a psychophysical experiment was conducted with 20 participants through a yes/no task under a wide luminance range (2-284 cd/m(2)). The participants were asked to adapt to the luminance of the HMD and further answer whether the test luminance of the HMD caused discomfort. The discomfort threshold was determined for each individual at each adaptation luminance, and a prediction model was proposed based on the mean value of each participant's discomfort luminance level. The proposed model represents that individuals may experience discomfort using an HMD with a luminance of about 280 cd/m(2), regardless of whether they are provided time to adapt to the luminance for 2 min