Validity of the linear viscoelastic model for a polymer cylinder with ultrasonic hysteresis-type absorption in a nonviscous fluid

A necessary condition for the validity of the linear viscoelastic model for a (passive) polymeric cylinder with an ultrasonic hysteresis-type absorption submerged in a non-viscous fluid requires that the absorption efficiency is positive (Qabs > 0) satisfying the law of the conservation of energy. This condition imposes restrictions on the values attributed to the normalized absorption coefficients for the compressional and shear-wave wavenumbers for each partial-wave mode n. The forbidden values produce negative axial radiation force, absorption and extinction efficiencies, as well as an enhancement of the scattering efficiency, not in agreement with the conservation of energy law. Numerical results for the radiation force, extinction, absorption and scattering efficiencies are performed for three viscoelastic (VE) polymer cylinders immersed in a non-viscous host liquid (i.e. water) with particular emphasis on the shear-wave absorption coefficient of the cylinder, the dimensionless size parameter and the partial-wave mode number n. Mathematical constraints are established for the non-dimensional absorption coefficients of the longitudinal and shear waves for a cylinder (i.e. 2D case) and a sphere (i.e. 3D case) in terms of the sound velocities in the VE material. The analysis suggests that the domain of validity for any viscoelastic model describing acoustic attenuation inside a lossy cylinder (or sphere) in a non-viscous fluid must be verified based upon the optical theorem

Diabetes and Risk of Non-Hodgkin's Lymphoma

OBJECTIVE: To examine the epidemiologic association between diabetes and risk of non-Hodgkin's lymphoma (NHL). RESEARCH DESIGN AND METHODS: We searched MEDLINE for observational studies on the association between diabetes and NHL in adults using the keywords "diabetes" and "lymphoma." Prospective cohort studies that reported relative risks or standardized incidence ratios and case-control studies that reported odds ratios with 95% CIs were included. A random-effects model was used to combine results from the individual studies. RESULTS: A total of 15 manuscripts (reporting data from 5 prospective cohort and 11 case-control studies) met the inclusion criteria. Combining data from all studies, the risk ratio (RR) of developing NHL in patients with diabetes was 1.19 (95% CI 1.04–1.35). Based on prospective studies, patients with diabetes had an RR of developing NHL of 1.41 (1.07–1.88), without heterogeneity among studies (I2 = 34.3%; P > 0.10). Based on case-control studies, patients with diabetes had an RR of 1.12 (95% CI 0.95–1.31) of developing NHL compared with people without diabetes, with some heterogeneity among studies (I2 = 36.28%; P = 0.09). CONCLUSIONS: Diabetes is associated with a moderately increased risk of NHL, which is consistent with other reported associations between diabetes and malignancies. Future studies should focus on elucidating potential pathophysiologic links between diabetes and NHL.National Institutes of Health grants (R01-DK76092, R0179003, and R2178867