Greater Beijing Research Articles

Prevalence and Associations of Vitreomacular Traction: The Beijing Eye Study.

PurposeTo explore the prevalence and associations of vitreous macular traction (VMT) in Chinese population.MethodsA population-based cross-sectional study with 3468 individuals (mean age of 64.6 ± 9.8 years) based on Beijing Eye Study 2011. Participants underwent detailed ophthalmic examinations, including spectral domain optical coherence tomography (SD-OCT). VMT was defined as abnormal posterior vitreous detachment with anatomical deformation of the fovea, which may include pseudocyst, macular schisis, cystoid macular edema, and subretinal fluid.Main Outcome MeasurePrevalence of VMT.ResultsA VMT was detected in 151 (2.3%) eyes (prevalence rate (mean ± SE): 2.3± 0.2%; 95% CI: 1.9%, 2.7%) of 80 (2.4%) subjects (prevalence rate: 2.4± 0.3%; 95% CI: 1.9%, 2.9%). Mean age of all subjects with VMT was 70.1± 8.7 years (median, 70.0 years; range, 50–90 years), mean refractive error was −0.22 ± 2.38D (median, 0.25 D; range, −15.00 to 5.25D). In multivariate analysis, prevalence of VMT was associated with elder age (P=0.001, OR 1.06), female gender (P = 0.036, OR 1.77), subfoveal retinal thickness (P = 0.005, OR 1.01), and subfoveal choroidal thickness (P = 0.026, OR 0.10).ConclusionIn adult Chinese in Greater Beijing, the prevalence of VMT was 2.3% for eyes or 2.4% for subjects. While it was associated with elder age, female gender, thicker subfoveal retinal thickness and thinner subfoveal choroidal thickness.

An Objective Approach to Generating Multi-Physics Ensemble Precipitation Forecasts Based on the WRF Model

Selecting proper parameterization scheme combinations for a particular application is of great interest to the Weather Research and Forecasting (WRF) model users. This study aims to develop an objective method for identifying a set of scheme combinations to form a multi-physics ensemble suitable for short-range precipitation forecasting in the Greater Beijing area. The ensemble is created by using statistical techniques and some heuristics. An initial sample of 90 scheme combinations was first generated by using Latin hypercube sampling (LHS). Then, after several rounds of screening, a final ensemble of 40 combinations were chosen. The ensemble forecasts generated for both the training and verification cases using these combinations were evaluated based on several verification metrics, including threat score (TS), Brier score (BS), relative operating characteristics (ROC), and ranked probability score (RPS). The results show that TS of the final ensemble improved by 9%-33% over that of the initial ensemble. The reliability was improved for rain ≤ 10 mm day-1, but decreased slightly for rain > 10 mm day-1 due to insufficient samples. The resolution remained about the same. The final ensemble forecasts were better than that generated from randomly sampled scheme combinations. These results suggest that the proposed approach is an effective way to select a multi-physics ensemble for generating accurate and reliable forecasts.

Prevalence and Associations of Fundus Tessellation Among Junior Students From Greater Beijing.

To determine the prevalence of fundus tessellation and associations with ocular and systemic parameters among junior students from Greater Beijing. The school-based study included 1443 individuals with a mean age of 12.4 ± 0.5 years (range: 9-16 years). All participants underwent a comprehensive ophthalmic examination and an interview. Fundus tessellation, defined as variation in the visibility of large choroidal vessels, was differentiated into three grades. The prevalence and degree of fundus tessellation were 688/1430 (48.1%; 95% confidence intervals [CI]: 45.5%, 50.7%) and 0.54 ± 0.61 (median, 0.00; range, 0-3), respectively. In multivariable regression analysis, a higher degree of fundus tessellation was associated with reduced subfoveal choroidal thickness (P < 0.001; beta, -0.02; odds ratio [OR], 0.98; 95% CI: 0.98, 0.99) and longer axial length (P < 0.001; beta, 0.23; OR, 1.25; 95% CI: 1.10, 1.43). Subfoveal choroidal thickness decreased from 299 ± 61 μm (95% CI: 293, 304) in eyes without fundus tessellation to 246 ± 57 μm (95% CI: 241, 251), 197 ± 43 μm (95% CI: 187, 207), and 131 ± 30 μm (95% CI: 93, 168) in eyes with grade 1, 2, and 3 fundus tessellation, respectively. A higher degree of peripapillary fundus tessellation was associated with reduced subfoveal choroidal thickness (P < 0.001; beta, -0.02; OR, 0.98; 95% CI: 0.98, 0.99) and younger age at myopia onset (P = 0.008; beta, 0.41; OR, 1.51; 95% CI: 1.11, 2.04). The prevalence of fundus tessellation is relatively high in Chinese teenagers. As in adults, the degree of fundus tessellation is a surrogate for choroidal thickness in teenagers. Marked fundus tessellation indicates a leptochoroid and is associated with earlier myopia onset.

There's Something in the Air in China

The citizens of greater Beijing were justifiably proud after hosting the 2008 Summer Olympic Games. The opening and closing ceremonies were spectacular. Architectural feats abounded, including the ...

Visual Impairment and Spectacle Use in Schoolchildren in Rural and Urban Regions in Beijing

To determine prevalence and associations of visual impairment and frequency of spectacle use among grade 1 and grade 4 students in Beijing. This school-based, cross-sectional study included 382 grade 1 children (age 6.3 ± 0.5 years) and 299 grade 4 children (age 9.4 ± 0.7 years) who underwent a comprehensive eye examination including visual acuity, noncycloplegic refractometry, and ocular biometry. Presenting visual acuity (mean 0.04 ± 0.17 logMAR) was associated with younger age (p = 0.002), hyperopic refractive error (p<0.001), and male sex (p = 0.03). Presenting visual impairment (presenting visual acuity ≤20/40 in the better eye) was found in 44 children (prevalence 6.64 ± 1.0% [95% confidence interval (CI) 4.74, 8.54]). Mean best-corrected visual acuity (right eyes -0.02 ± 0.04 logMAR) was associated with more hyperopic refractive error (p = 0.03) and rural region of habitation (p<0.001). The prevalence of best-corrected visual impairment (best-corrected visual acuity ≤20/40 in the better eye) was 2/652 (0.30 ± 0.21% [95% CI 0.00, 0.72]). Undercorrection of refractive error was present in 53 children (7.99 ± 1.05%) and was associated with older age (p = 0.003; B 0.53; OR 1.71 [95% CI 1.20, 2.42]), myopic refractive error (p = 0.001; B -0.72; OR 0.49 [95% CI 0.35, 0.68]), and longer axial length (p = 0.002; B 0.74; OR 2.10 [95% CI 1.32, 3.32]). Spectacle use was reported for 54 children (8.14 ± 1.06%). Mean refractive error of the worse eyes of these children was -2.09 ± 2.88 D (range -7.38 to +7.25 D). Factors associated with presenting visual impairment were older age, myopic refractive error, and higher maternal education level. Despite a prevalence of myopia of 33% in young schoolchildren in Greater Beijing, prevalence of best-corrected visual impairment (0.30% ± 0.21%), presenting visual impairment (6.64% ± 1.0%), and undercorrection of refractive error (7.99% ± 1.05%) were relatively low.

Marketing Raw Milk from Dairy Farmers before and after the 2008 Milk Scandal in China: Evidence from Greater Beijing

ABSTRACTChina's 2008 milk scandal severely impacted its dairy industry. Afterwards, the government took prompt efforts to regulate and enhance food safety standards. For example, a dairy marketing management policy was implemented, and concentrated dairy complexes were recommended as options for smallholder dairy farmers. The results of this study show that the policies affected marketing channels at the farm gate. Since then, new dairy complexes have emerged and are becoming the primary marketing channel for milk. The marketing transformation has profound implications for food safety, and has strengthened vertical coordination in the Chinese dairy chain.

Impact of urbanization on changes in temperature extremes in Beijing during 1978–2008

To quantify the impact of urbanization on changes in observed surface air temperature and extremes, a homogenized dataset of daily mean, maximum and minimum temperature (Tm, Tmax and Tmin) observations at 20 stations in Greater Beijing (GBJ) from 1978 to 2008 is analyzed. In contrast with previous studies, a cluster analysis is done to objectively classify observing stations into four categories (urbanized, suburban, rural and mountain), which is checked with remote-sensing night-light images since the 1990s. At urbanized sites, there is an added warming trend in annual mean Tm representing an average of 10.9% (up to 18.4% or 0.12°C/decade at the most strongly influenced site) of overall warming. Corresponding contributions for Tmin are 12.7% (up to 20.8% or 0.19°C/decade) and 24% for diurnal temperature range DTR (up to 37.4% or 0.149°C/decade) over the last three decades. Although it has not had a significant impact on daytime records (Tmax), urbanization has enhanced the increasing (decreasing) trend of extremely warm (cold) nights by an average of 12.7% or 2.07 d/decade (29.0% or 5.06 d/decade) at the urbanized sites since the 1970s.

Myopic Shift and Outdoor Activity among Primary School Children: One-Year Follow-Up Study in Beijing

PurposeTo assess whether a change in myopia related oculometric parameters of primary school children in Beijing was associated with indoors and outdoors activity.MethodsThe longitudinal school-based study included school children who were examined in 2011 and who were re-examined in 2012. The children underwent a comprehensive eye examination including ocular biometry by optical low-coherence reflectometry and non-cycloplegic refractometry. Parents and children had a detailed interview including questions on time spent indoors and outdoors.ResultsOut of 681 students examined at baseline, 643 (94.4%) returned for follow-up examination. Within the one-year period, mean time spent daily outdoors increased by 0.4±0.9 hours, mean axial length by 0.26±0.49 mm, the ratio of axial length divided by anterior corneal curvature (AL/CC) by 0.03±0.06, and myopic refractive error by −0.06±0.89 diopters. In multivariate analysis, elongation of axial length was significantly associated with less total time spent outdoors (P = 0.02; standardized coefficient beta −0.12) and more time spent indoors with studying (P = 0.007; beta: 0.14) after adjustment for maternal myopia (P = 0.02; beta: 0.12). An increase in AL/CC was significantly associated with less time spent outdoors (P = 0.01; beta:−0.12) after adjustment for paternal myopia (P = 0.003; beta: 0.15) and if region of habitation was excludedors for leisure (P = 0.006; beta:−0.13), with less total time spent outdoors (P = 0.04; beta:−0.10), or with more time spent i. An increase in myopic refractive error, after adjustment for age, was significantly associated with less time spent outdo ndoors with studying (P = 0.005; beta: 0.13).ConclusionsA change in oculometric parameters indicating an increase in myopia was significantly associated with less time spent outdoors and more time spent indoors in school children in Greater Beijing within a study period of one year. Our study provides additional information on the potentially helpful role of outdoors activity in the prevention of myopia. Public health care measures such as school agendas may potentially take it into account.

Prevalence and associations of incomplete posterior vitreous detachment in adult Chinese: the Beijing Eye Study.

PurposeTo determine prevalence and associations of incomplete posterior vitreous detachment (PVD).MethodsThe population-based cross-sectional Beijing Eye Study 2011 included 3468 individuals with a mean age of 64.6±9.8 years (range: 50–93 years). A detailed ophthalmic examination was performed including spectral-domain optical coherence tomography (SD-OCT). Incomplete PVD was differentiated into type 1 (shallow PVD with circular perifoveal vitreous attachment), type 2 (PVD reaching fovea but not foveola), type 3 (shallow PVD with pinpoint vitreous attachment at the foveola), and type 4 (PVD completely detached from the macula, attached to the optic disc).ResultsAn incomplete PVD was detected in 3948 eyes (prevalence: 60.5±0.6%; 95% Confidence Interval (CI): 59.3%,61.7%) of 2198 subjects (67.1±0.8%;95%CI: 65.6%,68.7%). Type 1 PVD was seen in 3090 (78.3%) eyes, type 2 PVD in 504 (12.8%) eyes, type 3 PVD in 70 (1.8%) eyes, and type 4 PVD in 284 (7.2%) eyes. Prevalence of incomplete PVD was associated with younger age (P<0.001;OR:0.91), male gender (P<0.001;OR:0.64), rural region of habitation (P<0.001;OR:0.49), larger corneal diameter (P = 0.04;OR:0.91), better best corrected visual acuity (P = 0.02;OR:0.41), and hyperopic refractive error (P<0.001;OR:1.15). The type of incomplete PVD was associated with higher age (P<0.001), urban region of habitation (P<0.001), myopic refractive error (P = 0.001), thinner cornea (P = 0.005), and better best corrected visual acuity (P = 0.056).ConclusionsIn adult Chinese in Greater Beijing, prevalence of an incomplete PVD (detected in 67.1% subjects) was associated with younger age, male gender, rural region of habitation, larger corneal diameter, better best corrected visual acuity and hyperopic refractive error.

The 10-Year Incidence and Risk Factors of Retinal Vein Occlusion: The Beijing Eye Study

To assess the 10-year incidence of retinal vein occlusions (RVOs) and associated factors in adult Chinese subjects. Population-based, longitudinal study. The Beijing Eye Study, which included 4439 subjects (age: 40+ years) in 2001, was repeated in 2011 with 2695 subjects participating (66.4% of the survivors). The study participants underwent a detailed ophthalmic examination. Fundus photographs were examined for the new development of RVOs, differentiated into branch RVOs (BRVOs) and central RVOs (CRVOs). Incidence of RVOs. Incident RVOs were detected in 51 eyes (49 subjects) with an incidence of 1.9 ± 0.1 per 100 persons and 1.0 ± 0.1 per 100 eyes. Incidence of BRVO was 1.6 ± 0.1 per 100 subjects (43 subjects [88% of patients with RVO]; 44 eyes), and incidence of CRVO was 0.3 ± 0.1 per 100 persons. Of 61 patients with an RVO in 2001 and 25 subjects reexamined in 2011, at least 4 subjects (7%) developed a second RVO. Incident BRVOs were located more often in the superior temporal quadrant and inferior temporal quadrant (32% and 34%, respectively) than in the superior nasal quadrant and inferior nasal quadrant (21% and 14%, respectively). In 35 eyes (80% of the BRVO eyes), the BRVO was located at an arteriovenous crossing. At the crossing sites, arterioles were found superficial to venules in 28 eyes (64% of the BRVO eyes). Macular edema was detected in 18 (37%) of all RVO eyes, including 13 (30%) of BRVO eyes. In multivariate logistic analysis, incident RVOs were associated with higher systolic blood pressure (P = 0.01; odds ratio [OR], 1.04), hypertension (P = 0.03; OR, 4.62), lower cognitive function score (P = 0.007; OR, 0.88), blood concentration of cholesterol ≥ 5.72 mmol/L (P = 0.007; OR, 3.29), and status after cerebral infarction/hemorrhage (P = 0.02; OR, 1.19). Incident RVOs were not significantly related to the intake of aspirin (P=0.37). The 10-year incidence of RVOs in Greater Beijing (1.9 ± 0.1 per 100 persons) was similar to that in other studies on Caucasian populations. The 10-year incidence of RVOs was related to the known risk factors of arterial hypertension, hypercholesterolemia, and status after cerebral infarction/hemorrhage, as well as with a lower cognitive function score. Incident BRVO was approximately 6 times more frequent than incident CRVO. Macular edema was detected in approximately 30% of BRVO eyes.

Keratoconus: prevalence and associations

Evaluation of: Xu L, Wang YX, Guo Y, You QS, Jonas JB; the Beijing Eye Study Group. Prevalence and associations of steep cornea/keratoconus in Greater Beijing. The Beijing Eye Study. PLoS One 7(7), e39313 (2012).According to the Beijing Eye Study, which was conducted in Chinese adults over the age of 50 years living in Greater Beijing (with steep cornea/keratoconus as corneal refractive power of ≥48 diopters), the prevalence of steep cornea/keratoconus was reported to be 0.9 + 0.2%. The prevalence of steep cornea/keratoconus was significantly associated with the ocular parameters of shorter axial length, smaller interpupillary distance, higher cylindrical, myopic refractive error and lower best corrected visual acuity. None of the systemic parameters were tested, such as gender, body height, psychic depression, cognitive function, blood concentrations of glucose, lipids, creatinine and C-reactive protein, blood pressure, quality of life score or ocular factors, such intraocular pressure, dry-feeling eyes, and lens thickness, showed any significant association with steep cornea/keratoconus.

Outdoor Activity and Myopia among Primary Students in Rural and Urban Regions of Beijing

To assess associations among outdoor activity, ocular biometric parameters, and myopia among grade 1 and grade 4 primary students in Beijing. School-based, cross-sectional study. A total of 382 grade 1 and 299 grade 4 children participated in the study. The children underwent a comprehensive eye examination, including ocular biometry by optical low-coherence reflectometry and noncycloplegic refractometry. Parents and children participated in a detailed interview, including questions on time spent indoors and outdoors. Factors associated with myopia. The study included 681 children, with 382 (56.1%) students from grade 1 (mean age, 6.3 ± 0.5 years; range, 5-8 years) and 299 students from grade 4 (mean age, 9.4 ± 0.7 years; range, 8-13 years); 370 students (54.3%) lived in the urban region. The mean daily time spent outdoors was 1.6 ± 0.8 hours (range, 0.5-5.1 hours). In multivariate analysis, axial length was significantly associated with older age (P<0.001; standardized β coefficient, 0.28), taller body height (P = 0.001; β, 0.18), maternal myopia (P = 0.03; β, 0.09), and urban region of habitation (P<0.001; β, -0.21), or alternatively to the region of habitation, with less time spent outdoors (P = 0.001; β, -0.16) and more time spent indoors studying (P = 0.02; β, 0.10). The axial length-to-corneal curvature radius ratio was associated with older age, urban region of habitation, maternal and paternal myopia, and paternal level of education. Presence of myopia (defined as refractive error ≤-1 diopters in the right eye) was associated with older age (P<0.001; odds ratio [OR], 1.45; 95% confidence interval [CI], 1.24-1.69), maternal myopia (P<0.001; OR, 2.99; 95% CI, 1.94-5.35), and urban region of habitation (P<0.001; OR, 0.17; 95% CI, 0.11-0.26), or alternatively to the region of habitation, with less time spent outdoors (P<0.001; OR, 0.32; 95% CI, 0.21-0.48) and more time spent indoors studying (P<0.001; OR, 1.38; 95% CI, 1.09-1.75). Less outdoor activity, more indoor studying, older age, maternal myopia, and urban region of habitation were associated with longer ocular axial length and myopia in grade 1 and grade 4 primary school children in Greater Beijing. Remaining outdoors more (e.g., during school) may reduce the high prevalence of myopia in the young generation in Beijing.

Prevalence and associations of steep cornea/keratoconus in Greater Beijing. The Beijing Eye Study.

PurposeTo evaluate the prevalence and associated factors of steep cornea/keratoconus in the adult Chinese population.MethodsThe population-based Beijing Eye Study 2011 included 3468 individuals with a mean age of 64.6±9.8 years (range: 50–93 years). A detailed ophthalmic examination was performed including optical low-coherence reflectometry. Steep cornea/keratoconus were defined as an anterior corneal refractive power exceeding 48 diopters.ResultsMean refractive power of the cornea was 43.16±1.45 diopters (range: 36.51 to 48.46 diopters; flattest meridian) and 43.98±1.52 diopters (range: 37.00 to 52.88 diopters; steepest meridian). A steep cornea/keratoconus defined as corneal refractive power of ≥48 diopters and ≥49 diopters was detected in 27 subjects (prevalence rate: 0.9±0.2%) and 6 (0.2± 0.1%) subjects, respectively. Presence of steep cornea/keratoconus was associated with shorter axial length (P<0.001), smaller interpupillary distance (P = 0.038), lower best corrected visual acuity (P = 0.021), higher cylindrical refractive error (P<0.001) and more myopic refractive error (P<0.001). It was not significantly associated with gender, body height, psychic depression, cognitive function, blood concentrations of glucose, lipids, creatinine and C-reactive protein, blood pressure and quality of life score, nor with intraocular pressure, dry eye feeling, and lens thickness.ConclusionsA steep cornea/keratoconus defined as corneal refractive power of 48+ diopters has a prevalence of 0.9±0.2% among Chinese aged 50 years and above. Its prevalence was significantly associated with the ocular parameters of shorter axial length, smaller interpupillary distance, higher cylindrical and myopic refractive error and lower best corrected visual acuity, however, with none of the systemic parameters tested.

Five Year Incidence of Visual Field Loss in Adult Chinese. The Beijing Eye Study.

PurposeTo describe the cumulative 5 year incidence of visual field loss in adult Chinese in Greater Beijing.MethodsThe Beijing Eye Study 2006 included 3251 subjects (mean age 60.4±10.1 years) who had participated in the Beijing Eye Study 2001 and returned for re-examination. All participants underwent a comprehensive eye examination, including visual field test by frequency doubling threshold perimetry. An abnormal visual field was defined as reduced sensitivity in at least one test location. Incident visual field loss was defined as a change in visual field from normal at baseline to abnormal at follow-up.ResultsAn incident visual field loss was detected in 273 eyes (4.3±0.5%) /235 subjects (7.3±0.5%). It was significantly associated with higher age (P = 0.001), higher intraocular pressure (P<0.001), and higher fasting blood glucose concentration (P = 0.019). Considering only eyes (n = 140) with a detected cause for visual field loss, the most frequent causes were cataract (68 (48.6%) eyes) followed by glaucoma (23 (16.4%) eyes), diabetic retinopathy (13 (9.3%) eyes), age-related macular degeneration (10 (7.1%) eyes), and myopic degenerative retinopathy (9 (6.4%) eyes). For 133 (48.7%) eyes with a visual field loss, the cause for the VFL remained unclear.ConclusionsThe 5-year incidence of visual field loss was 4.3±0.5% per eye or 7.3±0.5% per subject. It increased significantly with age, intraocular pressure, and fasting blood glucose level. Major causes for the incidence of visual field loss were cataract, glaucoma and diabetic retinopathy.

Five-Year Follow-Up of Parapapillary Atrophy: The Beijing Eye Study

PurposeTo assess longitudinal changes in parapapillary atrophy in the adult population of Greater Beijing.MethodsThe population-based Beijing Eye Study 2006 included 3251 subjects who had participated in the Beijing Eye Study 2001 and returned for re-examination. The mean age was 60.4±10.1 years. Using optic disc photographs, we measured parapapillary atrophy which was divided into alpha zone and beta zone.ResultsOverall progression rate of alpha zone was seen in 0.6±0.1% (95% confidence interval (CI):0.3,0.9) of the subjects and of beta zone in 8.2±0.5% (95%CI:7.2,9.1) of the subjects. In binary regression analysis, rate of progression of alpha zone was significantly associated higher age (P = 0.04) and the co-progression of zone Beta (P<0.001). Rate of progression of beta zone was significantly associated with higher age (P<0.001; odds ratio (OR):1.11;95%CI:1.10,1.14), higher intraocular pressure (P<0.001;OR:1.10;95%CI:1.05,1.14), higher myopic refractive error (P<0.001;OR:0.71; 95%CI:0.67,0.75), rural region of habitation (P = 0.002;OR: 0.58; 95%CI:0.41,0.82), presence of glaucomatous optic nerve damage (P<0.001;OR:2.89; 95%CI:1.62,5.14), co-progression of alpha zone (P<0.001;OR:7.13;95%CI:2.43,20.9), absence of arterial hypertension (P = 0.03;OR: 0.70; 95%CI:0.51,0.96), and thicker central corneal thickness (P = 0.02;OR:1.01;95%CI:1.00,1.01). Subjects with a non-glaucomatous optic nerve damage (n = 22) as compared to the remaining subjects did not vary in the progression rate of alpha zone (0.0% versus 0.6±0.1%; P = 1.0) and beta zone (8.2±0.5% versus 6.3±0.6%;P = 1.0).ConclusionsIn adult Chinese in Greater Beijing, the 5-year progression rate of beta zone of parapapillary atrophy (seen in 8.2±0.5% of subjects) was significantly correlated with higher age, rural region of habitation, absence of arterial hypertension, higher intraocular pressure, higher myopic refractive error, thicker central corneal thickness, and presence of glaucoma. It was not associated with non-glaucomatous optic nerve damage.

Checking into China's cow hotels: Have policies following the milk scandal changed the structure of the dairy sector?

China's milk scandal is well known for causing the nation's largest food safety crisis and for its effect on thousands of children. Less, however, is known about the effect on the other victim: China's small dairy farmers. Although small backyard producers were not the ones that added melamine to the milk supply, the incomes of dairy farmers fell sharply after the crisis. In response, one of the actions taken by the government was to encourage small dairy producers to check into production complexes that were supposed to supply services, new technologies, and provide for easy/bulk procurement of the milk produced by the cows of the farmers. Because both farmers and their cows were living (and working) away from home, in the rest of the paper we call these complexes cow hotels. In this paper we examine the dynamics of China's dairy production structure before and after the milk scandal. In particular, we seek to gain a better understanding about how China's policies have been successful in encouraging farmers to move from the backyard into cow hotels. We also seek to find if larger or smaller farmers respond differently to these policy measures. Using data from a sample of farmers from dairy-producing villages in Greater Beijing, our empirical analysis finds that 1 yr after the milk scandal, the dairy production structure changed substantially. Approximately one quarter (26%) of the sample checked into cow hotels after the milk scandal, increasing from 2% before the crisis. Our results also demonstrate that the increase in cow hotel production can largely be attributed to China's dairy policies. Finally, our results suggest that the effects of government policy differ across farm sizes; China's dairy policies are more likely to persuade larger farms to join cow hotels. Apparently, larger farms benefit more when they join cow hotels. Overall, these results suggest that during the first year after the crisis, the government policies were effective in moving some of the backyard farmers into cow hotels (although 60% farmers remained backyard producing).

Prevalence and Associated Factors of Dyslipidemia in the Adult Chinese Population

To determine the prevalence, associated factors, awareness and control of dyslipidemia in Chinese living in Greater Beijing, we measured the serum cholesterol concentration in 3251 Chinese adults (age: 45 to 89 years) as participants of the population-based Beijing Eye Study 2006. Additional information on treatment of dyslipidemia was obtained using a standard questionnaire. The mean concentrations of total, HDL cholesterol, LDL cholesterol and triglycerides were 4.92±1.01 mmol/L, 1.61±0.36 mmol/L, 2.88±0.85 mmol/L, and 1.76±1.29 mmol/L, respectively. Prevalence of dyslipidemia was 56.1±0.9%%. Presence of dyslipidemia was significantly associated with increasing age (odds ratio (OR):1.02; 95% confidence interval (CI): 1.01, 1.03), female gender (OR:1.51; 95%CI: 1.25, 1.83), urban region (OR:1.82; 95%CI: 1.30, 2.55), body mass index (OR:1.13; 95%CI: 1.10, 1.15), income (OR:1.11; 95%CI:1.02, 1.21), blood glucose concentration (OR:1.10; 95%CI:1.05, 1.16), diastolic blood pressure (OR:1.02; 95%CI: 1.01, 1.03), and smoking (OR:1.23; 1.01, 1.51). Among those who had dyslipidemia, the proportion of subjects who were aware, treated and controlled was 50.9%, 23.8%, and 39.91%, respectively. The awareness rate was associated with urban region (P = 0.001; OR: 6.50), body mass index (P = 0.001; OR:1.06), and income (P = 0.02; OR:1.14). The data suggest that dyslipidemia may be present in about 56% of the population aged 45+ years in Greater Beijing. Factors likely associated with dyslipidemia were higher age, female gender, urban region, higher body mass index, higher income, higher blood concentration of glucose, higher diastolic blood pressure, and smoking. In the examined study population, treatment rate was 24% with about 60% of the treated subjects still having uncontrolled dyslipidemia.

Five-Year Incidence of Visual Impairment and Blindness in Adult Chinese: The Beijing Eye Study

To describe the cumulative 5-year incidence of visual impairment and blindness in adult Chinese in greater Beijing. Population-based study. The Beijing Eye Study 2006 included 3251 subjects who had participated in the Beijing Eye Study 2001 and returned for re-examination. Using the World Health Organization (WHO) definition, low vision and blindness were defined as best corrected visual acutiy (BCVA) <20/60 to 20/400 and as BCVA <20/400 in the better-seeing eye, respectively. Using the United States standard, low vision and blindness were defined as BCVA <20/40 to 20/200 and as BCVA <20/200 in the better-seeing eye, respectively. Incidence of low vision and blindness. Visual acuity measurements were available for 3249 (99.9%) participants. Using WHO and United States definitions, the incidences of low vision and blindness were 0.5 ± 0.1% (mean ± standard error) and 0.1 ± 0.04%, and 1.1 ± 0.2% and 0.1 ± 0.04%, respectively. In multivariate analysis, incidence of BCVA visual impairment or blindness increased significantly with greater age (P = 0.01), but was not associated with gender, region, or level of education. Causes of BCVA visual impairment or blindness were cataract (39%), glaucoma (17%), and degenerative myopia (11%). Using the WHO and the United States criteria, incidences of low vision and blindness based on presenting visual acuity, were 1.7 ± 0.2% and 0.1 ± 0.06%, and 3.8 ± 0.3% and 0.2 ± 0.08%, respectively. Incidence of visual impairment or blindness (presenting visual acuity, WHO definition) increased significantly with higher age (P < 0.001) and less education (P = 0.018) and was greater in women (P = 0.015). The major cause of presenting VA visual impairment or blindness was undercorrected refractive error (76%). In adult Chinese in greater Beijing, the 5-year cumulative incidence of BCVA visual impairment or blindness was 0.6 ± 0.1% (BCVA in better-seeing eye, <20/60) or 1.7 ± 0.2% (presenting VA in better-seeing eye, <20/60), which increased significantly with age. Measured as presenting VA, this also was associated with female gender and rural region. The major cause (76%) of decreased presenting VA was undercorrected refractive error, followed by cataract. Treating undercorrection of refractive error may be the easiest and most efficient method to improve vision in this community. Proprietary or commercial disclosure may be found after the references.

Marketing China's milk: A case study of the sales activity of dairy farmers in greater Beijing

Small farmer participation in marketing chains in emerging commodity markets and the determinants of their marketing channel choices are the center of many recent empirical and theoretical papers in the literature. The dairy sector is emerging in China. There are many fundamental questions about how farmers make dairy marketing decisions in China at the farm gate level that are unanswered. This makes the dairy sector in China a good place to study farmers in emerging marketing chains. Based on three sets of unique data collected in the mid-2000s in Greater Beijing, the analyses show that small farmers were the major producers of milk. There is no evidence that small farmers are being excluded from emerging marketing channels. One of the differences of China's dairy sector in the mid-2000s is that its marketing chain itself had many different types of agents that procure milk — and few of them were large; most were individual entrepreneurs. The high level of the competiveness may be the reason that individual agents do not have monopoly power and why small farmers can operate in the system. ►The dairy sector is emerging in China. ►Small farmers were the major producers of milk. ►Small farmers were not being excluded from emerging marketing channels.

Farmer Participation, Processing, and the Rise of Dairy Production in Greater Beijing, P. R. China

With rapid income growth, dairy production and consumption in China have increased significantly. The emergence of the dairy sector provides opportunities for farmers to participate in a high‐value, potentially more lucrative enterprise. The overall goal of this paper is to analyze the major determinants of farmer participation in dairy production. Our main questions include whether or not the pace of the emergence of the dairy processing industry has affected the ability of farmers (especially small and relatively poor ones) to participate in dairy production; and whether or not it has limited the expansion of their herd size. Based on household, village, and processor surveys conducted in the Greater Beijing region, our analysis indicates that the location of dairy processing firms is one key factor that determines the participation of farmers in dairy production. Although other factors affect participation and herd size, including road access and the ability to find employment off the farm (which affects the opportunity cost of household members), the proximity to a dairy processor is shown to be one of the major factors that has encouraged the growth of dairy production for a given farmer in a specific region during the past decade. The results also show that poor, less educated farmers with relatively less access to land are not excluded from the expansion of the Greater Beijing dairy market. La production laitière et la consommation ont augmenté considérablement en Chine, en raison de la croissance rapide du revenu. Pour les producteurs, la croissance du secteur laitier offre des occasions de se lancer dans des activités à forte valeur, potentiellement plus lucratives. L’objectif global du présent article consiste à analyser les principaux déterminants de la participation des producteurs à la production laitière. Nous nous sommes alors posé deux questions. Le rythme d’émergence de l’industrie de la transformation de produits laitiers influence‐t‐il ou non la capacité des producteurs (en particulier les petits producteurs de condition modeste) à se lancer dans la production laitière? Le rythme d’émergence de cette industrie limite‐t‐il ou non l’expansion de la taille de leurs troupeaux? Une analyse des enquêtes menées auprès des ménages, des villages et des transformateurs dans l’agglomération pékinoise a révélé que le lieu où se trouvent les entreprises de transformation de produits laitiers est l’un des principaux facteurs qui déterminent la participation des producteurs à la production laitière. Bien que d’autres facteurs influencent la participation des producteurs et la taille des troupeaux, notamment l’accès routier et la capacitéà trouver un emploi à l’extérieur de la ferme (qui influence le coût d’opportunité/d’option des membres du ménage), la proximité d’une usine de transformation serait l’un des principaux facteurs qui ont encouragé la croissance de la production laitière, pour un producteur donné dans une région en particulier, au cours des dix dernières années. Les résultats ont également indiqué que les producteurs de condition modeste, moins instruits et ayant un accès restreint à des terres ne sont pas exclus de l’expansion du marché laitier dans l’agglomération pékinoise.