Study of the (p,Pi) Reaction in the Two-Nucleon Model

This work was supported by the National Science Foundation Grants NSF PHY 78-22774 A03, NSF PHY 81-14339, and by Indiana Universit

Detecting changes in sediment overburden using distributed temperature sensing: an experimental and numerical study

Fibre optic cables can be used as sensors to monitor temperature changes through the analysis of back scattered light. This can be linked to changes in the ambient conditions surrounding the fibre optic cable. Active distributed temperature sensing relies on an external heat source relative to the fibre optic cable to measure the properties of, and changes in, the surrounding medium. An experiment was conducted using distributed temperature sensing technology to monitor changes in sediment overburden for the purpose of determining whether scour could be measured above buried power cables containing fibre optic cables. Fibre optic cables were buried in a channel containing saturated sand and water with an external heat source. The depth of overburden sediment above the fibre optic cables was reduced, whilst the associated temperature response along the fibre optic cable was monitored. The data was matched to a finite element model so that the heat transfer taking place could be simulated and then the thermal conductivity of the soil modified to observe the potential changes in heat detected by the fibre optic cables. This paper explains the characteristics of heat transfer from an active heat source to the surrounding soil medium providing a means to translate the temperature measurement to the associated overburden thickness and to model the same response in different materials

Fibre optic monitoring of a deep circular excavation

This paper describes part of the monitoring undertaken at Abbey Mills shaft F, one of the main shafts of Thames Water's Lee tunnel project in London, UK. This shaft, with an external diameter of 30 m and 73 m deep, is one of the largest ever constructed in the UK and consequently penetrates layered and challenging ground conditions (Terrace Gravel, London Clay, Lambeth Group, Thanet Sand Formation, Chalk Formation). Three out of the twenty 1·2 m thick and 84 m deep diaphragm wall panels were equipped with fibre optic instrumentation. Bending and circumferential hoop strains were measured using Brillouin optical time-domain reflectometry and analysis technologies. These measurements showed that the overall radial movement of the wall was very small. Prior to excavation during a dewatering trial, the shaft may have experienced three-dimensional deformation due to differential water pressures. During excavation, the measured hoop and bending strains of the wall in the chalk exceeded the predictions. This appears to be related to the verticality tolerances of the diaphragm wall and lower circumferential hoop stiffness of the diaphragm walls at deep depths. The findings from this case study provide valuable information for future deep shafts in London. The authors would like to thank Thames Water Ltd and the Lee Tunnel Project Management Team for making the field study possible in the first place.This is the accepted manuscript. The final version is available from ICE Publishing at http://www.icevirtuallibrary.com/content/article/10.1680/geng.13.00036

Multi-dimensional simulation of underground subway spaces coupled with geoenergy systems

Old and deep subway lines suffer from overheating problems, particularly during summer, which is detrimental for passenger comfort and health. Geothermal systems could serve as one of the potential energy efficient cooling solutions, compared to energy intensive conventional cooling. The waste heat of the subway tunnel can be harnessed, to provide heating to residential and commercial blocks above the tunnels. This paper presents a multi-scale co-simulation framework for quantifying the amount of useful heat that can be extracted from overheated underground subway tunnels using geothermal heat exchangers. The co-simulation is applied and tested on a representative section of the London Underground's Central Line. The Central Line is modelled using a 1D heat and mass transfer model. The geothermal system, on the other hand, is represented using a 3D finite element model. The 1D and 3D models are co-simulated, using the subway tunnel's outer wall temperatures as boundary conditions. The model is run parametrically to identify the best arrangement and depth of geothermal heat exchangers for extracting excess heat from subway tunnels. Results show that the depth of 15 m. below the tunnel is sufficient for vertical closed loop heat exchangers to yield temperature drop of 4C in the subway tunnel and platforms. Partially insulated boreholes, alternating between extracting and injecting heat into the soil, are also assessed for their potential to provide heating and cooling demand simultaneously and improve the overall geothermal system efficiency. The heat extracted along a representative section of the tunnels is compared to the heating demand of the buildings above ground

Soft tissue window of CT scans in the initial stage of ONJ: A case report

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BCAA catabolism in brown fat controls energy homeostasis through SLC25A44.

Branched-chain amino acid (BCAA; valine, leucine and isoleucine) supplementation is often beneficial to energy expenditure; however, increased circulating levels of BCAA are linked to obesity and diabetes. The mechanisms of this paradox remain unclear. Here we report that, on cold exposure, brown adipose tissue (BAT) actively utilizes BCAA in the mitochondria for thermogenesis and promotes systemic BCAA clearance in mice and humans. In turn, a BAT-specific defect in BCAA catabolism attenuates systemic BCAA clearance, BAT fuel oxidation and thermogenesis, leading to diet-induced obesity and glucose intolerance. Mechanistically, active BCAA catabolism in BAT is mediated by SLC25A44, which transports BCAAs into mitochondria. Our results suggest that BAT serves as a key metabolic filter that controls BCAA clearance via SLC25A44, thereby contributing to the improvement of metabolic health