Stray light analysis and suppression method of a pancake virtual reality head-mounted display.

Pancake virtual reality head-mounted displays (VR-HMDs) have attracted the attention of researchers in both academia and industry because of the compact size and light weight. However, owing to the use of optical path folding, there exist various stray lights in the optical system, which seriously degrades user experience. In this study, we analyze the causes and effects of multiple types of stray light systematically and design a VR-HMD with low stray light, large exit pupil diameter (EPD), compact form and light weight. Subsequently, several effective stray light suppression solutions are proposed and implemented. Finally, a prototype of a compact pancake VR-HMD system is successfully demonstrated. The prototype has stray light of less than 2.3%, a diagonal field of view (FOV) of 96° and an EPD of 10 mm at an 11 mm eye relief (ERF).

Design, stray light analysis, and fabrication of a compact head-mounted display using freeform prisms.

It has been a challenge to design an optical see-through head-mounted display that is compact, lightweight, and stray-light-suppressed by using freeform optics. A new type of design based on freeform prisms is presented. The system consists of three optical elements and a micro-display. Two prisms serve as near-eye viewing optics that magnify the image displayed by the micro-display, and the other freeform lens is an auxiliary element attached to the main wedge-shaped prism to provide an undistorted see-through view of a real-world scene. The overall thickness of the optical system does not exceed 9.5 mm, and the weight is less than 9.8 g per eye. The final system is based on a 0.49-inch micro-display and features a diagonal field of view of 38°, an F/number of 1.8, with a 10 mm × 7 mm exit pupil diameter, and a 19 mm eye relief. The causes of stray light in the optical-mechanical system are investigated, and effective solutions or theoretical suppression of stray light are given. The freeform optical elements are successfully fabricated, and the system performance is carefully investigated. The results show that the performance of the optical see-through head-mounted display is adequate for practical applications.

Optical design and pupil swim analysis of a compact, large EPD and immersive VR head mounted display.

Virtual reality head-mounted displays (VR-HMDs) are crucial to Metaverse which appears to be one of the most popular terms to have been adopted over the internet recently. It provides basic infrastructure and entrance to cater for the next evolution of social interaction, and it has already been widely used in many fields. The VR-HMDs with traditional aspherical or Fresnel optics are not suitable for long-term usage because of the image quality, system size, and weight. In this study, we designed and developed a large exit pupil diameter (EPD), compact, and lightweight VR-HMD with catadioptric optics. The mathematical formula for designing the catadioptric VR optics is derived. The reason why this kind of immersive VR optics could achieve a compact size and large EPD simultaneously is answered. Various catadioptric forms are systematically proposed and compared. The design can achieve a diagonal field of view (FOV) of 96° at -1 diopter, with an EPD of 10 mm at 11 mm eye relief (ERF). The overall length (OAL) of the system was less than 20 mm. A prototype of a compact catadioptric VR-HMD system was successfully developed.

Bronze and Iron Age population movements underlie Xinjiang population history.

The Xinjiang region in northwest China is a historically important geographical passage between East and West Eurasia. By sequencing 201 ancient genomes from 39 archaeological sites, we clarify the complex demographic history of this region. Bronze Age Xinjiang populations are characterized by four major ancestries related to Early Bronze Age cultures from the central and eastern Steppe, Central Asian, and Tarim Basin regions. Admixtures between Middle and Late Bronze Age Steppe cultures continued during the Late Bronze and Iron Ages, along with an inflow of East and Central Asian ancestry. Historical era populations show similar admixed and diverse ancestries as those of present-day Xinjiang populations. These results document the influence that East and West Eurasian populations have had over time in the different regions of Xinjiang.

Mechanistic/mammalian target of rapamycin and side effects of antipsychotics: insights into mechanisms and implications for therapy.

Antipsychotic pharmacotherapy has been widely recommended as the standard of care for the treatment of acute schizophrenia and psychotic symptoms of other psychiatric disorders. However, there are growing concerns regarding antipsychotic-induced side effects, including weight gain, metabolic syndrome (MetS), and extrapyramidal motor disorders, which not only decrease patient compliance, but also predispose to diabetes and cardiovascular diseases. To date, most studies and reviews on the mechanisms of antipsychotic-induced metabolic side effects have focused on central nervous system mediation of appetite and food intake. However, disturbance in glucose and lipid metabolism, and hepatic steatosis induced by antipsychotic drugs might precede weight gain and MetS. Recent studies have demonstrated that the mechanistic/mammalian target of rapamycin (mTOR) pathway plays a critical regulatory role in the pathophysiology of antipsychotic drug-induced disorders of hepatic glucose and lipid metabolism. Furthermore, antipsychotic drugs promote striatal mTOR pathway activation that contributes to extrapyramidal motor side effects. Although recent findings have advanced the understanding of the role of the mTOR pathway in antipsychotic-induced side effects, few reviews have been conducted on this emerging topic. In this review, we synthesize key findings by focusing on the roles of the hepatic and striatal mTOR pathways in the pathogenesis of metabolic and extrapyramidal side effects, respectively. We further discuss the potential therapeutic benefits of normalizing excessive mTOR pathway activation with mTOR specific inhibitors. A deeper understanding of pathogenesis may inform future intervention strategies using the pharmacological or genetic inhibitors of mTOR to prevent and manage antipsychotic-induced side effects.

Current Smoking is a Risk Factor for the Irregular Surface and Calcification of Carotid Plaque in Men.

OBJECTIVE: To explore whether current smoking could influence plaque characteristics and determine its correlation to the irregular surface and calcification of carotid plaque. METHODS: Three hundred and seventeen patients with severe carotid atherosclerosis stenosis (SCAS) detected by color duplex flow imaging (CDFI) and confirmed by CT angiography (CTA) were recruited. The results of laboratory parameters were collected by using electronic database of the hospital. Computerized tomography (CT) scanning and high-resolution ultrasonography were performed for assessment of plaque morphology, respectively. RESULTS: All enrolled smokers and non-smokers had no significant difference among all characteristics not related to smoking. CT scanning could efficiently identify the difference among enrolled smokers and non-smokers not only for the characteristics related to smoking but also the onsets of carotid plaque. Surface morphology was also efficiently detected by ultrasonography. Further ridge trace analysis showed that ultrasonography is efficient for diagnosis of calcified plaque compared with gold standard for plaque diagnosis. Further correlation analysis showed that ultrasonography parameters could offer reliable evidence for plaque scores, which was associated with age index. Ultrasonography parameters could efficiently differentiate plaque morphologies among enrolled smokers and never-smokers. CONCLUSION: Current smoking was positively associated with plaque calcification onsets, and smoking cessation could efficiently attenuate such injury. High-frequency ultrasound can clearly distinguish the details of calcification with promising clinical significance for current smoking patients.

Correlation Between Calcification Characteristics of Carotid Atherosclerotic Plaque and Plaque Vulnerability.

PURPOSE: To investigate the relationship between calcification characteristics of carotid atherosclerotic plaque and lipid rich necrotic core (LRNC) and intraplaque hemorrhage (IPH). METHODS: Patients with severe carotid stenosis undergoing carotid endarterectomy (CEA) were selected. Ultrasound and CT angiography (CTA) were performed to evaluate the calcification characteristics of the plaque before the surgery. RESULTS: A total of 142 patients were included and 142 pathological specimens of postoperative plaque were obtained accordingly. There were 78 plaques (54.9%) with LRNC and 41 (28.9%) with IPH. The plaque with LRNC had higher calcification rate (93.6%) compared with the plaque with IPH (87.8%). LRNC was often found in multiple calcification (P = 0.003) and mixed type calcification (P = 0.001). Multiple calcification was more likely to combine with IPH (P = 0.008), while simple basal calcification was not likely to combine IPH (P = 0.002). Smaller granular calcification was more likely to be associated with IPH (P < 0.05). In multivariate regression analysis of IPH and calcification characteristics, simple basal calcification was still a protective factor for IPH (OR, 0.25; 95% CI, 0.09-0.66; P = 0.005), while multiple calcification was closely related to the occurrence of IPH (OR, 3.58; 95% CI, 1.49-8.61; P = 0.004). CONCLUSION: Calcification characteristics of carotid atherosclerotic plaques are closely related to the vulnerability of plaques, especially multiple calcification and mixed type calcification.

Ancient Xinjiang mitogenomes reveal intense admixture with high genetic diversity.

Xinjiang is a key region in northwestern China, connecting East and West Eurasian populations and cultures for thousands of years. To understand the genetic history of Xinjiang, we sequenced 237 complete ancient human mitochondrial genomes from the Bronze Age through Historical Era (41 archaeological sites). Overall, the Bronze Age Xinjiang populations show high diversity and regional genetic affinities with Steppe and northeastern Asian populations along with a deep ancient Siberian connection for the Tarim Basin Xiaohe individuals. In the Iron Age, in general, Steppe-related and northeastern Asian admixture intensified, with North and East Xinjiang populations showing more affinity with northeastern Asians and South Xinjiang populations showing more affinity with Central Asians. The genetic structure observed in the Historical Era of Xinjiang is similar to that in the Iron Age, demonstrating genetic continuity since the Iron Age with some additional genetic admixture with populations surrounding the Xinjiang region.

Maternal genetic structure in ancient Shandong between 9500 and 1800 years ago.

Archaeological and ancient DNA studies revealed that Shandong, a multi-culture center in northern coastal China, was home to ancient populations having ancestry related to both northern and southern East Asian populations. However, the limited temporal and geographical range of previous studies have been insufficient to describe the population history of this region in greater detail. Here, we report the analysis of 86 complete mitochondrial genomes from the remains of 9500 to 1800-year-old humans from 12 archaeological sites across Shandong. For samples older than 4600 years before present (BP), we found haplogroups D4, D5, B4c1, and B5b2, which are observed in present-day northern and southern East Asians. For samples younger than 4600 BP, haplogroups C (C7a1 and C7b), M9 (M9a1), and F (F1a1, F2a, and F4a1) begin to appear, indicating changes in the Shandong maternal genetic structure starting from the beginning of the Longshan cultural period. Within Shandong, the genetic exchange is possible between the coastal and inland regions after 3100 BP. We also discovered the B5b2 lineage in Shandong populations, with the oldest Bianbian individual likely related to the ancestors of some East Asians and North Asians. By reconstructing a maternal genetic structure of Shandong populations, we provide greater resolution of the population dynamics of the northern coastal East Asia over the past nine thousand years.