Analytical model for grouted rock bolts

This paper presents an analytical model of the grouted rock bolt in soft rock. The behavior of both the rock bolt system and the single rock bolt are discussed respectively. The coupling mechanism of rock bolt and rock mass is discussed from the viewpoint of displacement. A simple method is suggested for the rock bolt design in tunneling. According to the analysis, displacement of rock mass controls the initial force in rock mass. Case simulations confirm the previous findings that a bolt in-situ has a pick-up length, an anchor length and at least one neutral point. The theoretical prediction of single rock bolt agrees with the measured data. The position of the neutral point is not only related to the length of the rock bolt and the internal radius of the tunnel, but is also strongly influenced by the properties of rock mass. Neutral point and maximum axial load in the rock bolt tend to be constant when the anchor length of the bolt is sufficiently long, which means that increasing the length of the rock bolt may result in only a slight improvement in displacement control under certain conditions

CKD, Brain Atrophy, and White Matter Lesion Volume: The Japan Prospective Studies Collaboration for Aging and DementiaPlain-Language summary

Rationale &amp; Objective: Chronic kidney disease, defined by albuminuria and/or reduced estimated glomerular filtration rate (eGFR), has been reported to be associated with brain atrophy and/or higher white matter lesion volume (WMLV), but there are few large-scale population-based studies assessing this issue. This study aimed to examine the associations between the urinary albumin-creatinine ratio (UACR) and eGFR levels and brain atrophy and WMLV in a large-scale community-dwelling older population of Japanese. Study Design: Population-based cross-sectional study. Setting &amp; Participants: A total of 8,630 dementia-free community-dwelling Japanese aged greater than or equal to 65 years underwent brain magnetic resonance imaging scanning and screening examination of health status in 2016-2018. Exposures: UACR and eGFR levels. Outcomes: The total brain volume (TBV)-to-intracranial volume (ICV) ratio (TBV/ICV), the regional brain volume-to-TBV ratio, and the WMLV-to-ICV ratio (WMLV/ICV). Analytical Approach: The associations of UACR and eGFR levels with the TBV/ICV, the regional brain volume-to-TBV ratio, and the WMLV/ICV were assessed by using an analysis of covariance. Results: Higher UACR levels were significantly associated with lower TBV/ICV and higher geometric mean values of the WMLV/ICV (P for trend = 0.009 and <0.001, respectively). Lower eGFR levels were significantly associated with lower TBV/ICV, but not clearly associated with WMLV/ICV. In addition, higher UACR levels, but not lower eGFR, were significantly associated with lower temporal cortex volume-to-TBV ratio and lower hippocampal volume-to-TBV ratio. Limitations: Cross-sectional study, misclassification of UACR or eGFR levels, generalizability to other ethnicities and younger populations, and residual confounding factors. Conclusions: The present study demonstrated that higher UACR was associated with brain atrophy, especially in the temporal cortex and hippocampus, and with increased WMLV. These findings suggest that chronic kidney disease is involved in the progression of morphologic brain changes associated with cognitive impairment