An Anisotropic Velocity Model for Microseismic Events Localization in Tunnels.

The velocity model is one of the main factors affecting the accuracy of microseismic event localization. This paper addresses the issue of the low accuracy of microseismic event localization in tunnels and, combined with active-source technology, proposes a "source-station" velocity model. The velocity model assumes that the velocity from the source to each station is different, and it can greatly improve the accuracy of the time-difference-of-arrival algorithm. At the same time, for the case of multiple active sources, the MLKNN algorithm was selected as the velocity model selection method through comparative testing. The results of numerical simulation and laboratory tests in the tunnel showed that the average location accuracy of the "source-station" velocity model was improved compared with that of the isotropic velocity and sectional velocity models, with numerical simulation experiments improving accuracy by 79.82% and 57.05% (from 13.28 m and 6.24 m to 2.68 m), and laboratory tests in the tunnel improving accuracy by 89.26% and 76.33% (from 6.61 m and 3.00 m to 0.71 m). The results of the experiments showed that the method proposed in this paper can effectively improve the location accuracy of microseismic events in tunnels.

Risk of Alzheimer's disease and related dementia by sex and race/ethnicity: The Multiethnic Cohort Study.

INTRODUCTION: Data are limited for comparison of sex- and race/ethnicity-specific risks of Alzheimer's disease and related dementia (ADRD). METHODS: In the population-based Multiethnic Cohort, we estimated the age-standardized diagnostic incidence rate (ASDIR) and relative risk of late-onset ADRD (n = 16,410) among 105,796 participants based on Medicare claims (1999-2014) by sex and race/ethnicity. RESULTS: The ASDIR for ADRD was higher for women (17.0 per 1000 person-years) than for men (15.3) and varied across African Americans (22.9 in women, 21.5 in men), Native Hawaiians (19.3, 19.4), Latinos (16.8, 14.7), Whites (16.4, 15.5), Japanese Americans (14.8, 13.8), and Filipinos (12.5, 9.7). Similar risk patterns were observed for AD. Adjustment for education and cardiometabolic diseases attenuated the differences. Accounting for deaths from competing causes increased the sex difference, while reducing the racial/ethnic differences. Less racial/ethnic disparity was detected among apolipoprotein E (APOE) e4 carriers. DISCUSSION: More research is needed to understand the sex and racial/ethnic differences in ADRD.

Red meat consumption, cooking mutagens, NAT1/2 genotypes and pancreatic cancer risk in two ethnically diverse prospective cohorts.

There is limited evidence on the association between red meat consumption and pancreatic cancer among ethnic minorities. We assessed this relationship in two large prospective cohorts: the Multiethnic Cohort Study (MEC) and the Southern Community Cohort Study (SCCS). Demographic, dietary and other risk factor data were collected at cohort entry. Red meat intake was assessed using cohort-specific validated food frequency questionnaires. Incident pancreatic cancer cases were identified via linkages to state cancer registries. Cox regression was used to calculate relative risks (RRs) and 95% confidence intervals (CIs) for the association of red meat intake with pancreatic cancer risk in each cohort. We performed additional analyses to evaluate cooking methods, mutagens and effect modification by NAT1/2 genotypes. From a total of 184 542 (MEC) and 66 793 (SCCS) at-risk participants, we identified 1618 (MEC) and 266 (SCCS) incident pancreatic cancer cases. Red meat consumption was associated with pancreatic cancer risk in the MEC (RRQ4vsQ1 1.18, 95% CI 1.02-1.37) and with borderline statistical significance in the SCCS (RRQ4vsQ1 1.31, 95% CI 0.93-1.86). This association was significant in African Americans (RRQ4vsQ1 1.49, 95% CI 1.06-2.11) and Latinos (RRQ4vsQ1 1.44, 95% CI 1.02-2.04) in the MEC, and among African Americans (RRQ4vsQ1 1.55, 95% CI 1.03-2.33) in the SCCS. NAT2 genotypes appeared to modify the relationship between red meat and pancreatic cancer in the MEC (pinteraction = 0.03). Our findings suggest that the associations for red meat may be strongest in African Americans and Latinos. The mechanisms underlying the increased risk for these populations should be further investigated.

Cancer Mortality Patterns by Birthplace and Generation Status of Mexican Latinos: The Multiethnic Cohort.

BACKGROUND: Latinos are the largest minority group in the United States. We assessed cancer mortality by birthplace and generation status of Mexican Latinos in the Multiethnic Cohort. METHODS: We included 26 751 Latinos of Mexican origin and 6093 non-Latino Whites aged 45-74 years at cohort entry (1993-1996) from the California Multiethnic Cohort component. The Mexican Latinos comprised 42% first-generation Mexico-born immigrants, 42% second-generation (28% US-born with both parents Mexico-born and 14% US-born with 1 parent US-born and 1 parent Mexico-born), and 16% third-generation or more who were US-born with both parents US-born. Multivariable Cox models were used to calculate covariate adjusted hazard ratios and 95% confidence intervals for overall and site-specific cancer mortality by birthplace and generation status. All statistical tests were 2-sided. RESULTS: Cancer death rate was highest among the US-born with 1 parent US-born and 1 parent Mexico-born (age-adjusted rate = 471.0 per 100 000 person-years) and US-born with both parents US-born (age-adjusted rate = 469.0 per 100 000 person-years) groups. The US-born with both parents Mexico-born group had a 30% (hazard ratio = 1.30, 95% confidence interval = 1.18 to 1.44) higher risk of cancer death than the first-generation Mexico-born immigrants group, showing US birthplace was associated with an elevated cancer mortality. For cancer-specific mortality, US birthplace was positively associated with colorectal, liver and lung, and ovarian cancer (P values ranged from .04 to .005). Among US-born Mexican Latinos, generation status was not statistically significantly associated with overall cancer or site-specific cancer mortality. CONCLUSIONS: Our findings suggest that US birthplace is a risk factor for cancer death in Mexican Americans. Identification of the contributing factors is important to curtail patterns of increasing cancer mortality in US-born Mexican Latinos.

Etiology and Outcomes of Hepatocellular Carcinoma in an Ethnically Diverse Population: The Multiethnic Cohort.

BACKGROUNDS: HCC incidence varies by race/ethnicity. We characterized racial differences in underlying etiology, presentation, and survival in the linkage of Multiethnic Cohort Study with SEER and Medicare claims. METHODS: HCC characteristics, treatment, and underlying etiology in participants were obtained. Deaths were ascertained using state death certificates and the National Death Index. Risk factors were collected via questionnaires. Cox models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for death. RESULTS: Among 359 cases, the average age at diagnosis was 75.1. The most common etiology was hepatitis C (HCV) (33%), followed by nonalcoholic fatty liver disease (NAFLD) (31%), and different by ethnicity (p < 0.0001). African Americans (AA) (59.5%) and Latinos (40.6%) were more likely to be diagnosed with HCV-related HCC. In Japanese Americans (33.1%), Native Hawaiians (39.1%), and whites (34.8%), NAFLD was the most common etiology. Receipt of treatment varied across ethnic groups (p = 0.0005); AA had the highest proportion of no treatment (50.0%), followed by Latinos (45.3%), vs. whites (15.2%). HCC (72.2%) was the most common cause of death. In a multivariate analysis, AA (HR = 1.87; 95% CI: 1.06-3.28) had significantly higher mortality compared to whites. CONCLUSIONS: We found significant ethnic differences in HCC underlying etiology, receipt of treatment, and outcome. The findings are important for reducing disparities.

Racial/ethnic disparities in weight or BMI change in adulthood and pancreatic cancer incidence: The multiethnic cohort.

INTRODUCTION: Compared to non-Hispanic Whites, Japanese Americans, Native Hawaiians, and African Americans have higher incidences of pancreatic cancer (PCa) that are not entirely explained by rates of obesity but may be explained by weight changes throughout adulthood. METHODS: The multiethnic cohort is a population-based prospective cohort study that has followed 155,308 participants since its establishment between 1993 and 1996. A total of 1,328 incident cases with invasive PCa were identified through 2015. We conducted separate multivariable Cox proportional hazards models for self-reported weight-change and BMI-change (age 21 to cohort entry) to determine the association with PCa risk, adjusting for potential confounders including weight or BMI at age 21. RESULTS: The mean age at cohort entry was 59.3 years (SD 8.9). An increased risk of PCa was associated with: 1) weight (HR per10 lbs = 1.06; 95% CI = 1.03-1.09) or BMI (HR per kg/m2  = 1.04; 95% CI = 1.02-1.05) at age 21; and 2) weight (HR per 10 lbs = 1.03; 95% CI = 1.01-1.05) or BMI (HR = 1.02; 95% CI = 1.00-1.03) at cohort entry. We found increased risk of PCa between weight (HR per 10 lbs = 1.03; 95% CI = 1.01-1.05) and BMI (HR per 5 kg/m2  = 1.08; 95% CI = 1.01-1.15) change from age 21 to baseline. There were significant interactions between race/ethnicity and weight (p = 0.008) or BMI (p = 0.03) at baseline, and weight (p = 0.02) or BMI (p = 0.02) change. Weight and BMI change through adulthood significantly increased the risk of PCa for Japanese Americans and Latinos, but not for African American, White, or Hawaiian participants. CONCLUSION: Our findings indicate that weight or BMI gain has a significant and independent impact on PCa risk, specifically among Latinos and Japanese Americans.