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Background: The aim is to develop age-specific anti-Müllerian hormone (AMH) screening criteria for polycystic ovary syndrome (PCOS) to facilitate early detection and diagnosis of the condition and subsequently evaluate the screening criteria. Methods: A retrospective analysis was performed on patient data from Hangzhou Women’s Hospital between July 2021 and August 2024. The use of restricted cubic spline analysis helped identify age-related inflection points, which were crucial for segmenting the patient population. Statistical analysis was conducted using SPSS software, and the receiver operating characteristic curve was employed to determine the area under the curve, optimal AMH screening thresholds, sensitivity, specificity, Youden index, correct diagnosis rate, positive predictive value and negative predictive value. The established age-related AMH screening criteria for PCOS were then validated using a separate validation group. The consistency of the PCOS age-related AMH screening test with the 2003 Rotterdam PCOS diagnostic criteria was assessed using the kappa statistic. Results: The derived age-specific AMH screening thresholds for PCOS are as follows: ≥6.93 ng/mL (20–27 years old), ≥5.06 ng/mL (28–30 years old) and ≥4.19 ng/mL (31–39 years old). Conclusion: The age-stratified AMH screening criteria demonstrated high sensitivity, specificity and accuracy in identifying PCOS, indicating a strong predictive value. However, the development of more robust and universally applicable diagnostic criteria for PCOS will require additional multicenter, prospective clinical trials for further validation.

Accurate snowfall forecasting and quantitative snowfall estimation remain challenging due to the complexity and variability of snow microphysical properties. In this paper, the microphysical characteristics of snowfall in the Yanqing mountainous area of Beijing are investigated by using a Particle Size and Velocity (PARSIVEL) disdrometer. Results show that the high snowfall intensity process has large particle-size distribution (PSD) peak concentration, but the distribution of its spectrum width is much smaller than that of moderate or low snowfall intensity. When the snowfall intensity is high, the corresponding Dm value is smaller and the Nw value is larger. Comparison between the fitted μ−Λ relationship and the relationships of different locations show that there are regional differences. Based on dry snow samples, the Ze−SR relationship fitted in this paper is more consistent with the Ze−SR relationship of dry snow in Nanjing, China. The fitted ρs−Dm relationship of dry snow is close to the relationship in Pyeongchang, Republic of Korea, but the relationship of wet snow shows greatly difference. At last, the paper analyzes the statistics on velocity and diameter distribution of snow particles according to different snowfall intensities.