Abstract The prevention and control of myopia in Chinese children and adolescents has become a major public health issue. While maintaining increased outdoor activity as a cornerstone intervention, there is an urgent need to explore new complementary approaches that can be effectively implemented in both indoor and outdoor settings. In recent years, environmental spatial frequency has gained increasing attention as one of the key environmental factors influencing the development and progression of myopia. Both animal studies and human research have confirmed that indoor environments lacking mid to high spatial frequency components, often characterized as "visually impoverished", can promote axial elongation and myopia through mechanisms such as disruption of retinal neural signaling, impaired accommodative function, and altered expression of related molecules. Based on the scientific consensus, it is recommended that "enriching of environmental spatial frequency" should be integrated into the myopia prevention and control framework. Following the principles of schoolled organization, family cooperation, community involvement, and student participation, specific measures are put forward in three areas：optimizing school visual settings, improving home spatial environments, and promoting healthy visual behavior. The aim is to create "visually friendly" indoor environments as an important supplement to outdoor activity, thereby providing a novel perspective and strategy for comprehensively advancing myopia prevention and control among children and adolescents.

Objective: To understand the subjective and objective comfort evaluations of students from different age groups on desks and chairs, so as to provide reference for standardized allocation and use of desks and chairs. Methods: From January to April 2024, a total of 2 446 students were selected from 26 schools in 13 districts (counties/cities) in Shanghai, Tianjin, and Wuxi from Jiangsu Province by using cluster random method, including students in kindergartens, primary schools, junior high schools,senior high schools, colleges and universities. Standardized procedures were used to measure the height and weight of participants, and the matching desks and chairs models were selected according to the height. The subjective comfort of students on matching desks and chairs was investigated, and their objective comfort was evaluated by using a self designed questionnaire. The χ 2 test was used to analyze the differences of subjective perception and objective evaluation in comfort between different types of desks and chairs. Results: About 84.1% of the students subjectively thought that large desks and small chairs were very comfortable or relatively comfortable, followed by large desks and chairs (75.7%), and the proportion of small desks and chairs was the lowest among the three types (46.2%), and the difference was statistically significant ( χ 2=722.46, P <0.01). The reporting rates of primary school, junior high school and senior high school students who subjectively considered large desks and chairs to be very comfortable/relatively comfortable were higher than that of other types of desks and chairs, and the differences were statistically significant ( χ 2=297.49, 252.82, 343.67, P <0.01). However, there was no significant difference in the subjective comfort evaluation of different types of desks and chairs among kindergarten children ( χ 2=3.21, P >0.05), and 66.3% of the students in colleges and universities felt very comfortable/relatively comfortable when they used the matching standard desks and chairs. The objective evaluation results of the comfort for the three types of desks and chairs were consistent with the subjective evaluation, but the proportions of the objective evaluation as very comfortable/relatively comfortable were higher than that of the subjective evaluation ( χ 2=20.76- 813.47, P <0.01). Conclusions Large desks and chairs, as well as large desks with small chairs are perceived comfortable, while small desks and chairs are perceived less comfortable. It is recommended to match the large desks and chairs or large desks and small chairs that are suitable for them according to the "standard", to promote physical and mental health of students.

Objective: To investigate the differences in the comfort of desks and chairs furniture among students with different body types according to the standard, so as to provide a reference for guiding students with overweight and obesity to choose the correct study furniture and revising the standards. Methods: From January to April 2024, 2 443 students from 26 schools in 13 districts (counties/cities) in Shanghai, Tianjin, and Jiangsu Province were selected by the cluster random sampling method to conduct physical examination. The subjective and objective evaluations of the comfort of height matched desks and chairs were investigated. The students were divided into non overweight, overweight, and obesity groups according to relevant criteria, and stratified analysis was performed. The χ 2 test was used to analyze differences in the comfort evaluations of desks and chairs among students with different body types. Results: Among the 2 443 students surveyed, 16.7% and 12.6% were respectively classified as overweight and obese. All students assigned the highest comfort ratings to large desks and small chairs (84.1%), and consistency was observed between students subjective and objective evaluations. The reporting rate of samll desks and chairs of obesity students subjective evaluation was lower (36.8%) than that of overweight and non overweight/obesity students (52.1%, 48.0%) ( χ 2=14.63, P <0.01). The overweight and obese group of primary school students had a worse evaluation of the comfort of large desks and chairs and small desks and chairs than those of the non overweight and obese groups( χ 2=15.78, 7.63, P <0.05). Among high school students, the overweight and obese group had worse evaluation of the comfort of large desks and chairs, as well as large desks and small chairs, than those of the non-overweight and obese groups( χ 2=9.62, 11.77, P <0.05). The objective evaluations revealed low compliance ratings on the posture of the thighs and calves for naturally forming an angle greater than 90° (55.6%), and headroom height under the table (50.3%) with small desks and chairs ( χ 2=94.05, 166.47, P <0.05). Conclusions Compared with non overweight/obese students, students with overweight and obese students report poor comfort evaluations of height matched desks and chairs. Revision of the standard should consider the body types of students, and evaluations of the comfort of desks and chairs furniture by students with overweight and obesity should be improved.

ObjectiveTo investigate the value of noninvasive imaging detection （FibroScan）， two serological models of gamma-glutamyl transpeptidase-to-platelet ratio （GPR） score and S index， and two inflammatory factors of interleukin-6 （IL-6） and tumor necrosis factor-α （TNF-α） in predicting liver fibrosis in patients with HBeAg-positive chronic hepatitis B （CHB）， as well as the consistency of liver biopsy in pathological staging， and to provide early warning for early intervention of CHB. MethodsA retrospective analysis was performed for 131 HBeAg-positive CHB patients who underwent liver biopsy in The Third People’s Hospital of Kunming from January 2019 to December 2023. The results of liver biopsy were collected from all patients， and related examinations were performed before liver biopsy， including total bilirubin， alanine aminotransferase， platelet count， gamma-glutamyl transpeptidase， albumin， IL-6， TNF-α， liver stiffness measurement （LSM）， and abdominal ultrasound. An analysis of variance was used for comparison of normally distributed continuous data between groups， and the Kruskal-Wallis H test was used for comparison of non-normally distributed continuous data between groups； the chi-square test was used for comparison of categorical data between groups. A Kappa analysis was used to investigate the consistency between LSM noninvasive histological staging and pathological staging based on liver biopsy， and the Spearman analysis was used to investigate the correlation between each variable and FibroScan in the diagnosis of liver fibrosis stage. The Logistic regression analysis was used to construct joint predictive factors. The receiver operating characteristic （ROC） curve was used to evaluate the value of each indicator alone and the joint predictive model in the diagnosis of liver fibrosis， and the Delong test was used for comparison of the area under the ROC curve （AUC）. ResultsIn the consistency check， inflammation degree based on liver biopsy had a Kappa value of 0.807 （P<0.001）， and liver fibrosis degree based on liver biopsy had a Kappa value of 0.827 （P<0.001）， suggesting that FibroScan noninvasive histological staging and liver biopsy showed good consistency in assessing inflammation degree and liver fibrosis stage. Age was positively correlated with LSM， GPR score， S index， IL-6， and TNF-α （all P<0.05）， and GPR score， S index， IL-6， and TNF-α were positively correlated with LSM （all P<0.05）. GPR score， S index， IL-6， and TNF-α were all independent risk factors for diagnosing significant liver fibrosis （≥S2） and progressive liver fibrosis （≥S3） （all P<0.05）. As for each indicator alone， GPR score had the highest value in the diagnosis of significant liver fibrosis （≥S2）， followed by S index， IL-6， and TNF-α， while S index had the highest value in the diagnosis of progressive liver fibrosis （≥S3）， followed by GPR score， TNF-α， and IL-6. The joint model had a higher predictive value than each indicator alone （all P<0.05）. ConclusionThere is a good consistency between FibroScan noninvasive histological staging and pathological staging based on liver biopsy. GPR score， S index， IL-6， and TNF-α are independent risk factors for evaluating different degree of liver fibrosis in CHB， and the combined prediction model established by them can better diagnose liver fibrosis.

ObjectiveTo unveil the mechanism of Jianpi Huogu prescription （JPHGP） in ameliorating the dyslipidemia of steroid-induced osteonecrosis of the femur head （SONFH） by oxylipidomics combined with transcriptomics. MethodsSixty SD rats were assigned into normal， model， low-， medium-， and high-dose （2.5， 5， 10 g·kg^-1， respectively） JPHGP， and Jiangushengwan （1.53 g·kg^-1） groups. Lipopolysaccharide was injected into the tail vein at a dose of 20 μg·kg^-1 on days 1 and 2， and methylprednisolone sodium succinate was injected at a dose of 40 mg·kg^-1 into the buttock muscle on days 3 to 5. The normal group received an equal volume of normal saline. Drug administration by gavage began 4 weeks after the last injection， and samples were taken after administration for 8 weeks. Hematoxylin-eosin staining was conducted to reveal the histopathological changes of the femoral head， and the number of adipocytes， the rate of empty bone lacunae， and the trabecular area were calculated. Micro-computed tomography was used for revealing the histological and histomorphometrical changes of the femoral head. Enzyme-linked immunosorbent assay was employed to measure the serum levels of triglyceride （TG）， total cholesterol （TC）， low-density lipoprotein （LDL）， high-density lipoprotein （HDL）， apolipoprotein A1 （ApoA1）， and apolipoprotein B （ApoB）. At the same time， the femoral head was collected for oxylipidomic and transcriptomic detection. The differential metabolites and differential genes were enriched and analyzed， and the target genes regulating lipid metabolism were predicted. The predicted target proteins were further verified by molecular docking， immunohistochemistry， and Western blot. ResultsCompared with the normal group， the model group showcased thinning of the femoral head， trabecular fracture， karyopyknosis， subchondral cystic degeneration， increases in the number of adipocytes and the rate of empty bone lacunae （P<0.01）， a reduction in the trabecular area （P<0.01）， decreases in BMD， Tb.Th， Tb.N， and BV/TV， and increases in Tb.Sp and BS/BV （P<0.01）. Compared with the model group， the JPHGP groups showed no obvious thinning of the femoral head or subchondroidal cystic degeneration. The high- and medium-dose JPHGP groups presented declines in the number of adipocytes and the rate of empty bone lacunae， an increase in the trabecular area （P<0.05， P<0.01）， rises in BMD， Tb.Th， Tb.N， and BV/TV， and decreases in Tb.Sp and BS/BV （P<0.05， P<0.01）. Compared with the normal group， the model group showcased raised serum levels of TG， TC， LDL， and ApoB and lowered serum levels of HDL and ApoA1 （P<0.01）. Compared with the model group， the JPHGP groups had lowered serum levels of TG， TC， LDL， and ApoB （P<0.05， P<0.01） and a risen serum level of ApoA1 （P<0.05， P<0.01）. Moreover， the serum level of HDL in the high-dose JPHGP group increased （P<0.01）. A total of 19 different metabolites of disease set and drug set were screened out by oxylipidomics of the femoral head， and 119 core genes with restored expression were detected by transcriptomics. The enriched pathways were mainly concentrated in inflammation， lipids， apoptosis， and osteoclast differentiation. Molecular docking， immunohistochemistry， and Western blot results showed that compared with the normal group， the model group displayed increased content of 5-lipoxygenase （5-LO） and peroxisome proliferator-activated receptor γ （PPARγ） in the femoral head （P<0.01）. Compared with the model group， medium- and high-dose JPHGP reduced the content of 5-LO and PPARγ （P<0.05， P<0.01）. ConclusionJPHGP can restore the levels of oxidized lipid metabolites by regulating the 5-LO-PPARγ axis to treat SONFH in rats. Relevant studies provide experimental evidence for the efficacy mechanism of JPHGP in the treatment of SONFH.

ObjectiveTo unveil the mechanism of Jianpi Huogu prescription （JPHGP） in ameliorating the dyslipidemia of steroid-induced osteonecrosis of the femur head （SONFH） by oxylipidomics combined with transcriptomics. MethodsSixty SD rats were assigned into normal， model， low-， medium-， and high-dose （2.5， 5， 10 g·kg^-1， respectively） JPHGP， and Jiangushengwan （1.53 g·kg^-1） groups. Lipopolysaccharide was injected into the tail vein at a dose of 20 μg·kg^-1 on days 1 and 2， and methylprednisolone sodium succinate was injected at a dose of 40 mg·kg^-1 into the buttock muscle on days 3 to 5. The normal group received an equal volume of normal saline. Drug administration by gavage began 4 weeks after the last injection， and samples were taken after administration for 8 weeks. Hematoxylin-eosin staining was conducted to reveal the histopathological changes of the femoral head， and the number of adipocytes， the rate of empty bone lacunae， and the trabecular area were calculated. Micro-computed tomography was used for revealing the histological and histomorphometrical changes of the femoral head. Enzyme-linked immunosorbent assay was employed to measure the serum levels of triglyceride （TG）， total cholesterol （TC）， low-density lipoprotein （LDL）， high-density lipoprotein （HDL）， apolipoprotein A1 （ApoA1）， and apolipoprotein B （ApoB）. At the same time， the femoral head was collected for oxylipidomic and transcriptomic detection. The differential metabolites and differential genes were enriched and analyzed， and the target genes regulating lipid metabolism were predicted. The predicted target proteins were further verified by molecular docking， immunohistochemistry， and Western blot. ResultsCompared with the normal group， the model group showcased thinning of the femoral head， trabecular fracture， karyopyknosis， subchondral cystic degeneration， increases in the number of adipocytes and the rate of empty bone lacunae （P<0.01）， a reduction in the trabecular area （P<0.01）， decreases in BMD， Tb.Th， Tb.N， and BV/TV， and increases in Tb.Sp and BS/BV （P<0.01）. Compared with the model group， the JPHGP groups showed no obvious thinning of the femoral head or subchondroidal cystic degeneration. The high- and medium-dose JPHGP groups presented declines in the number of adipocytes and the rate of empty bone lacunae， an increase in the trabecular area （P<0.05， P<0.01）， rises in BMD， Tb.Th， Tb.N， and BV/TV， and decreases in Tb.Sp and BS/BV （P<0.05， P<0.01）. Compared with the normal group， the model group showcased raised serum levels of TG， TC， LDL， and ApoB and lowered serum levels of HDL and ApoA1 （P<0.01）. Compared with the model group， the JPHGP groups had lowered serum levels of TG， TC， LDL， and ApoB （P<0.05， P<0.01） and a risen serum level of ApoA1 （P<0.05， P<0.01）. Moreover， the serum level of HDL in the high-dose JPHGP group increased （P<0.01）. A total of 19 different metabolites of disease set and drug set were screened out by oxylipidomics of the femoral head， and 119 core genes with restored expression were detected by transcriptomics. The enriched pathways were mainly concentrated in inflammation， lipids， apoptosis， and osteoclast differentiation. Molecular docking， immunohistochemistry， and Western blot results showed that compared with the normal group， the model group displayed increased content of 5-lipoxygenase （5-LO） and peroxisome proliferator-activated receptor γ （PPARγ） in the femoral head （P<0.01）. Compared with the model group， medium- and high-dose JPHGP reduced the content of 5-LO and PPARγ （P<0.05， P<0.01）. ConclusionJPHGP can restore the levels of oxidized lipid metabolites by regulating the 5-LO-PPARγ axis to treat SONFH in rats. Relevant studies provide experimental evidence for the efficacy mechanism of JPHGP in the treatment of SONFH.

Objective: To investigate the effect of a free pit and fissure sealing program for caries prevention on first permanent molars (six-year molars) in Haizhu District, Guangzhou, three years after its implementation in 2019. The study aims to provide a reference for the future development of pit and fissure sealing programs for children’s first permanent molars and the effective prevention and treatment of permanent tooth caries in children. Methods: A random sampling method was used. In 2022 October, 270 sixth-grade primary-school students in Haizhu District, Guangzhou, who had participated in the free pit and fissure sealing program for their first permanent molars in 2019, were placed in the sealant group. Another 223 age-matched students from the same schools who met the criteria for the pit and fissure sealing but did not participate in the program were placed in the control group. The first permanent molars of students in both groups were examined. The retention status of the sealant and the caries status of the first permanent molars were recorded for the sealant group, and the caries status of the first permanent molars was recorded for the control group. The 2022 results were compared with the results of a prior pit and fissure sealing program implemented in Haizhu District in 2011, three years after its implementation. Results: Compared with the control group, the caries rate in the sealant group decreased (15.56% vs. 21.52%, P>0.05), the caries detection rate was significantly lower (6.12% vs. 9.00%, P<0.001), and the mean number of decayed teeth was significantly reduced (0.19 vs. 0.37, P<0.001). Compared with the results of the pit and fissure sealing program in Haizhu District in 2011 (in 2014, the retention rate of the first permanent molar sealant was 65.56%, the intact rate was 42.25%, and the protection rate was 38.34%), the results of the pit and fissure sealing program in Haizhu District in 2019 [in 2022, the retention rate of the first permanent molar sealant was 86.09% (P<0.001), the intact rate was 47.00% (P<0.001), and the protection rate was 51.97%] were improved. Conclusion The quality of the pit and fissure sealing program for the first permanent molars in Haizhu District, Guangzhou in 2019 was good. It reduced the caries detection rate, and the retention rate of the sealant was maintained at a high level. However, the intact rate was less than 50%; therefore, it is necessary to vigorously promote oral-health education and examinations in all age groups, and to be attentive to the re-examination and re-sealing of fissure sealants.

ObjectiveTo investigate the therapeutic efficacy， influencing factors， and safety of a treatment regimen based on coblopasvir hydrochloride capsules/sofosbuvir tablets in patients with chronic hepatitis C virus （HCV） infection in a real-world setting. MethodsA total of 253 patients who attended The Third People’s Hospital of Kunming from September 1， 2021 to May 31， 2024 were enrolled， among whom there were 86 patients with compensated liver cirrhosis （CLC group） and 167 patients with chronic hepatitis C （CHC group）. The patients were treated with coblopasvir hydrochloride capsules （60 mg）/sofosbuvir tablets （400 mg） with or without ribavirin tablets for 12 weeks， and they were followed up for 12 weeks after drug withdrawal. The primary outcome measures were the rate of sustained virologic response at week 12 after treatment （SVR12） and safety， and the secondary outcome measures were the changes in liver function， renal function， blood routine， and liver stiffness measurements （LSM） after 4 weeks of treatment， after 12 weeks of treatment， and at 12 weeks after drug withdrawal. The independent-samples t test and the Mann-Whitney U test were used for comparison of continuous data between two groups， and the Friedman test was used for comparison between multiple groups， while the Bonferroni method was used for paired comparison within each group； the chi-square test was used for comparison of categorical data between two groups. The Logistic analysis was used to investigate related influencing factors. ResultsThe 253 patients with chronic HCV infection had a mean age of 49.38±8.65 years， and there were 151 male patients （59.7%）. Of all patients， 33.99% （86/253） had liver cirrhosis， 25.69% （65/253） had hypertension， 10.67% （27/253） had HIV infection， 8.70% （22/253） had diabetes， 3.95% （10/253） had liver cancer， 1.98% （5/253） had chronic hepatitis B， and 7.91% （20/253） were treatment-experienced patients. As for genotype distribution， 2.77% （7/253） had genotype 1， 12.65% （32/253） had genotype 2， 66.01% （167/253） had genotype 3， 16.60% （42/253） had genotype 6， and 1.98% （5/253） had unknown genotype. The patients had an overall SVR12 rate of 92.09%， with an SVR12 rate of 93.02% in the CLC group and 91.02% in the CHC group. The multivariate logistic regression analysis showed that age （odds ratio ［OR］=1.086， 95% confidence interval ［CI］： 1.007 — 1.170， P=0.032） and HCC （OR=9.178， 95%CI： 1.722 — 48.912， P=0.009） were independent influencing factors for sustained virologic response. Compared with baseline data， the CLC group had significant reductions in alanine aminotransferase （ALT） （χ²=107.103， P0.05）， aspartate aminotransferase （AST） （χ²=90.602， P0.05）， and LSM （χ²=42.235， P0.05） after 12 weeks of treatment， while the CHC group had significant reductions in total bilirubin （χ²=15.113， P0.05）， ALT （χ²=202.237， P0.05）， AST （χ²=161.193， P0.05）， and LSM （χ²=37.606， P0.05）. The incidence rate of serious adverse events was 1.58%， and none of the patients withdrew from drug therapy； the patients with such events were relieved after active symptomatic treatment. The incidence rate of all adverse events was 23.72%， among which fatigue （17.39%） and nausea （2.37%） were the most common adverse events， and these events often disappeared within 2 weeks or were gradually relieved after symptomatic treatment. ConclusionCoblopasvir hydrochloride capsules/sofosbuvir tablets with or without ribavirin tablets has good efficacy and safety in the treatment of chronic HCV infection.

Objective: To analyze epidemiological trends and changing characteristics of syphilis among students in Yunnan Province from 2005 to 2023, so as to provide evidence for the comprehensive prevention and control of syphilis in schools. Methods: The case data of syphilis among students in Yunnan Province from 2005 to 2023 were obtained from the China Information System for Disease Control and Prevention. The Joinpoint regression model was used to conduct a time trend analysis of the reported incidence rate of syphilis. Results: From 2005 to 2023, a cumulative total of 3 191 cases of syphilis were reported in schools in Yunnan Province(1 248 male cases and 1 943 female cases). The reported incidence rate rose continuously from 0.17/100 000 in 2005 to 8.26/100 000 in 2023, with an average annual percent change (AAPC) of 24.89%( Z =13.18, P <0.01). The reported incidence rate was higher in female students than in male students ( χ 2=229.48, P <0.05). The incidence rates in the primary school, junior high school, senior high school and higher education were 0.21/100 000, 2.42/100 000, 4.45/100 000 and 6.29/100 000 respectively, and the difference was statistically significant (χ 2=3 432.84, P <0.05). The average annual growth rate was the highest in the junior high school stage(AAPC= 30.68% , Z =7.57, P <0.05),followed by the senior high school stage (AAPC=24.28%, Z = 5.70 , P <0.05).The reported incidence rate of primary and secondary syphilis increased from 0.12/100 000 in 2005 to 2.06/ 100 000 in 2023, with an AAPC of 16.86% ( Z = 4.57, P <0.05). Conclusions The overall reported incidence rate of syphilis among students in schools in Yunnan Province shows a sustained upward trend, with the most rapid annual increase observed in junior high schools. Schools should prioritize syphilis education and expand awareness campaigns to curb transmission.

OBJECTIVE To compare the effects of leuprorelin and mifepristone on sex hormone levels， ovarian function， adverse reactions， and recurrence in patients with endometriosis （EMs） after surgery. METHODS A total of 178 patients who underwent surgical treatment for EMs in Ji’an Central People’s Hospital from September 2021 to September 2023 were randomly divided into the leuprorelin group and the mifepristone group， with 92 cases in each group. Medication was initiated on days 1 to 5 of the first menstrual cycle following surgery. Patients in the leuprorelin group received subcutaneous injections of Leuprorelin acetate microspheres， 3.75 mg per time， once every four weeks， for a total of 6 injections. Patients in the mifepristone group took 12.5 mg of Mifepristone capsules orally once daily for six consecutive months. Visual analog scale （VAS）， serum sex hormone levels [follicle-stimulating hormone （FSH）， luteinizing hormone （LH）， and estradiol （E2）]， ovarian function indicators [anti- Müllerian hormone （AMH）， antral follicle count （AFC）]， and T helper 1 cell （Th1）/Th2 shift markers [interferon-γ （IFN-γ）， interleukin 2 （IL-2）， IL-4， and IL-10] were compared between the two groups before surgery and after treatment. Incidence and outcome of adverse reactions and recurrence within one year were also compared between the two groups. RESULTS There were no statistically significant differences in baseline indicators between the two groups before surgery （P＞0.05）. After treatment， both groups showed significantly lower VAS scores for chronic pelvic pain， dysmenorrhea and dyspareunia， and significantly reduced serum FSH， LH， E2， IL-4 and IL-10 levels compared to before surgery （P＜0.05）， while serum IFN-γ and IL-2 levels were significantly increased （P＜0.05）； the leuprorelin group showed significantly greater improvements than the mifepristone group in all these indicators （P＜0.05）. After treatment， serum AMH levels in both groups were significantly lower than before surgery levels， while AFC was significantly increased （P＜0.05）； the leuprorelin group had significantly higher serum AMH levels and more AFC compared to the mifepristone group （P＜0.05）. There were no significant differences in the incidence of adverse reactions and outcome rates between the two groups （P＞0.05）. During one year of follow-up after discontinuation， the recurrence rate in the leuprorelin group was significantly lower than in the mifepristone group （1.15% vs. 10.99%， P＜0.05）. CONCLUSIONS Both leuprorelin and mifepristone are effective therapeutic drugs for EMs， but the former has advantages in alleviating pain， regulating serum sex hormone levels， protecting ovarian function， regulating immune function and reducing recurrence rates.