The Relationship between Brown Adipose Tissue Activity and Neoplastic Status: an 18F-FDG PET/CT Study in the Tropics

<p>Abstract</p> <p>Background</p> <p>Brown adipose tissue (BAT) has thermogenic potential. For its activation, cold exposure is considered a critical factor though other determinants have also been reported. The purpose of this study was to assess the relationship between neoplastic status and BAT activity by 2-deoxy-2-[18F]fluoro-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in people living in the tropics, where the influence of outdoor temperature was low.</p> <p>Methods</p> <p>¹⁸F-FDG PET/CT scans were reviewed and the total metabolic activity (TMA) of identified activated BAT quantified. The distribution and TMA of activated BAT were compared between patients with and without a cancer history. The neoplastic status of patients was scored according to their cancer history and ¹⁸F-FDG PET/CT findings. We evaluated the relationships between the TMA of BAT and neoplastic status along with other factors: age, body mass index, fasting blood sugar, gender, and outdoor temperature.</p> <p>Results</p> <p>Thirty of 1740 patients had activated BAT. Those with a cancer history had wider BAT distribution (<it>p </it>= 0.043) and a higher TMA (<it>p </it>= 0.028) than those without. A higher neoplastic status score was associated with a higher average TMA. Multivariate analyses showed that neoplastic status was the only factor significantly associated with the TMA of activated BAT (<it>p </it>= 0.016).</p> <p>Conclusions</p> <p>Neoplastic status is a critical determinant of BAT activity in patients living in the tropics. More active neoplastic status was associated with more vigorous TMA of BAT.</p

A Study of Precipitation Characteristics for Utah

Data on monthly precipitation for three areas of Southern Utah--Beaver, Cedar City and Ephraim--and three areas of Northern Utah--Salt Lake City, Ogden and Logan--where a series of measuring stations were arranged as traverses from the valleys to the mountain tops; were assembled and analyzed. The relationships between elevation and precipitation amounts were shown. The Southern Utah stations were drier at the same elevations than the Northern Utah stations and the differences became greater as the elevations increased. There was a close correlation between the high elevation and low elevation stations in the same traverse even with the above divergence. A higher percentage of the annual precipitation fell during the winter months at the Northern Utah stations than at the Southern Utah stations. These differences were also greater at the high elevations. There appears to be an elevation of maximum precipitation between 9000 and 10,000 feet. The annual precipitation decreases both above and below these elevations. A higher percentage of the years in Southern Utah are near the mean showing more uniformity than the stations in Northern Utah. These difference in not reflected in the numbers of consecutive dry years except when the consecutive years extend beyond 8 wherein the Northern Utah stations have had as many as 14 consecutive years of subnormal precipitation. The Northern Utah stations show the same trend in consecutive wet years, with the Logan record showing as many as 14 consecutive years with above normal precipitation. The Beaver precipitation record shoed a continually decreasing 5-year mean, while Salt Lake City and Logan records showed the opposite trend

Computation of stress intensity factors by the sub-region mixed finite element method of lines

Based on the sub-region generalized variational principle, a sub-region mixed version of the newly-developed semi-analytical 'finite element method of lines' (FEMOL) is proposed in this paper for accurate and efficient computation of stress intensity factors (SIFs) of two-dimensional notches/cracks. The circular regions surrounding notch/crack tips are taken as the complementary energy region in which a number of leading terms of singular solutions for stresses are used, with the sought SIFs being among the unknown coefficients. The rest of the arbitrary domain is taken as the potential energy region in which FEMOL is applied to obtain approximate displacements. A mixed system of ordinary differential equations (ODEs) and algebraic equations is derived via the sub-region generalized variational principle. A singularity removal technique that eliminates the stress parameters from the mixed equation system eventually yields a standard FEMOL ODE system, the solution of which is no longer singular and is simply and efficiently obtained using a standard general-purpose ODE solver. A number of numerical examples, including bi-material notches/cracks in anti-plane and plane elasticity, are given to show the generally excellent performance of the proposed method