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A novel bounding volume hierarchy (BVH) construction method based on locally dense clustering (LDC) was proposed for the low quality of BVH constructed in a complex scene with uneven distribution of primitives. The quality of the BVH was effectively improved by defining primitive density, analyzing the relation between density and traversal efficiency, selecting primitives with high density as the clustering center at the early stages of construction, and combining with top-down iterative clustering and bottom-up agglomerative clustering (AC). In order to effectively calculate primitive density, a local search strategy based on Morton coding was adopted. This strategy can quickly get approximate primitive density information through GPU. We evaluate the method and show that, in the complex building scene with uneven distribution of primitives, our method is 13% higher in traversal speed and 11% lower in surface area heuristic (SAH) cost. That means our method can improve the rendering speed of ray tracing effectively.

Background To investigate mental and physical health comorbidity with chronic back or neck pain in the Chinese population, and assess the level of disability associated with chronic back or neck pain. Methods Data were derived from a large-scale and nationally representative community survey of adult respondents on mental health disorders in China (n = 28,140). Chronic back or neck pain, other chronic pain conditions and chronic physical conditions were assessed by self-report. Mental disorders were assessed by the Composite International Diagnostic Interview (CIDI). Role disability during the past 30 days was assessed with the World Health Organization Disability Assessment Schedule (WHO-DAS-II). Results The 12-month prevalence of chronic back or neck pain was 10.8%. Most of respondents with chronic back or neck pain (71.2%) reported at least one other comorbid condition, including other chronic pain conditions (53.4%), chronic physical conditions (37.9%), and mental disorders (23.9%). It was found by logistic regression that mood disorders (OR = 3.7, 95%CI:2.8–4.8) showed stronger association with chronic back or neck pain than anxiety disorders and substance disorders. Most common chronic pains and physical conditions were significantly associated with chronic back or neck pain. Chronic back or neck pain was associated with role disability after controlling for demographics and for comorbidities. Physical and mental comorbidities explained 0.7% of the association between chronic back or neck pain and role disability. Conclusions Chronic back or neck pain and physical-mental comorbidity is very common in China and chronic back or neck pain may increase the likelihood of other physical and mental diseases. This presents a great challenge for both clinical treatment and public health education. We believe that further study needs to be conducted to improve the diagnostic and management skills for comorbidity conditions.

This study investigated the utilization of Mental Health Services (MHS) and associated predisposing, enabling, and need factors among residents of Shanghai, China. It used a cross-sectional design and a structured questionnaire. We selected 3502 residents aged 18 years and older through multi-stage, stratified random sampling; trained mental health personnel interviewed them. Multivariate logistic regression analysis explored the predictors of MHS utilization. Among respondents, approximately 21.4% reported depressive symptoms, whereas only 4.7% had utilized MHS. The factors that were significantly related to MHS utilization were the predisposing factors of gender, marital status, occupation, and mental health knowledge; the enabling factors of perceived need for mental health help, regular mental health resources, and government salvage objects; and the need factors of moderate and severe depressive symptoms. Underutilization of MHS in Shanghai is pervasive and worrisome. Interventions in the culture and environment to improve public mental health knowledge are crucial.

Background Though Chinese Traditional Medicine (TCM) is one of the most important parts of health care system in China, studies on the epidemiology of depression in TCM are scarce and mental health issues in TCM have been neglected for longtime. Methods This was an interview-based survey. The prevalence of depression and suicidal risk in outpatients at a TCM hospital was identified by a one-stage diagnosing process using the Mini International Neuropsychiatric Interview. Associated risk factors, role impairment, and service utility were also assessed. Results A total of 2000 outpatients aged from 18 to 65 years completed the survey with a response rate of 87.0%. The estimated prevalence of major depressive disorder was 13.2% for lifetime and 4.9% for current. No significant gender differences were found. Depression was more common in patients who lacked social support, experienced family economic burden and health burden, and underwent negative life events, poor self-rated health, or with moderate/severe sleep problem than in their correspondents; all with statistical significance (OR: 1.83–6.82). Patients with depression reported a mean of 82.7 days and 99.3 days of sick leave due to their physical and mental condition, respectively, which was much longer than those without depression (24.8 days and 25.8 days, respectively). Only 30.0% of patients with depression sought professional help from psychiatrists/psychologists or used antidepressants. Limitations The recall bias could not be ruled out in this study and could have led to an underestimation of true prevalence and the unmet need for treatment. Since this study was cross-sectional, the causal relationships between sociodemographic factors and depression cannot be determined. Conclusions Depression is common at TCM hospitals. The impairments due to depression are striking, and unmet needs for treatment are pervasive. Consequently, mental health services in TCM should not be neglected any longer.

Background Quality of life (QOL) is an important outcome measure for patients with depression, but QOL research involving large samples of patients has been uncommon. The purpose of this study was to evaluate the QOL of Chinese outpatients with depression and its determinants. Methods Using a cross-sectional survey design, data were collected continuously from 19,984 outpatients; 19,950 usable questionnaires were obtained. Along with the QOL index (WHOQOL-BREF), the questionnaire also included participants’ sociodemographic characteristics, outpatient visits, and medication use information. Results Less than 5% of depressed patients reported “good” or “very good” QOL, while less than 3% were satisfied with their general health. The overall score was low (54.12); four QOL domain (physical health, psychological, social relationships, and environment) scores (range, 35.03–40.10) were significantly lower than in other community population surveys. QOL scores were significantly lower among first-visit than non-first-visit patients. Medication users reported significantly higher QOL scores than non-users, with NaSSA more effective than SSRIs, followed by other types, SNRIs, and no medication, in that order. Limitations Since this was an observational, cross-sectional survey with continuous outpatient data collection method instead of random sampling, generalization of the results is limited, and causality cannot be determined. However, the “natural” observational design, large sample size, and similarity in findings with other studies reveal the “real world” QOL of depressed outpatients in mainland China. Conclusions Depressed patients had a low QOL, and the scores of first-visit patients with severe symptoms were significantly lower than non-first-visit patients. Though medication can improve patients’ QOL, different types of medications have different impacts.