The stretched exponential function has many applications in modeling numerous types of experimental relaxation data. However, problems arise when using standard algorithms to fit this function: we have observed that different initializations result in distinct fitted parameters. To avoid this problem, we developed a novel algorithm for fitting the stretched exponential model to relaxation data. This method is advantageous both because it requires only a single adjustable parameter and because it does not require initialization in the solution space. We tested this method on simulated data and experimental stress-relaxation data from bone and cartilage and found favorable results compared to a commonly-used Quasi-Newton method. For the simulated data, strong correlations were found between the simulated and fitted parameters suggesting that this method can accurately determine stretched exponential parameters. When this method was tested on experimental data, high quality fits were observed for both bone and cartilage stress-relaxation data that were significantly better than those determined with the Quasi-Newton algorithm.

Animal models are essential for understanding the fates and effects of inhaled materials, because invasive methods are frequently necessary to provide the desired information. Because of the variability in humans of particle deposition, clearance, and effects, numerous animal models have been used in inhalation studies. Furthermore, humans are not typical mammals in some ways that affect inhalation phenomena. Humans have less fur, longer gestation and life times, simplified nasal structure, and symmetric bronchial branching in relation to other mammals. However, experience, plus the genetic similarity among mammals, underpins the use of animal models. Mammals are varied with respect to their inhaled particle deposition and clearance phenomena. Total inhaled aerosol deposition probability versus particle-size curves are qualitatively similar for various mammals of similar body mass, despite airway anatomy differences. However, more species variation is seen in regional particle deposition curves, complicating aerosol study design. The rates of clearance of deposited slowly dissolving particles are animal species dependent, apparently due to differences in gross, subgross, and cellular respiratory tract biology. Clearance rates for rapidly dissolving particles are not strongly species dependent. Inhalation toxicology studies require several animal species. Rodents are among the most frequently used, but for studies of lung development, diseases, exercise, etc., and for extrapolation to humans, larger mammals are also needed. Fortunately, the research database, and excellent monographs on inhalation phenomena provide ample guidance for study design.

CONTEXT:Few studies have assessed the longer-term quality of preventive care in prostate cancer (PCa) survivors. OBJECTIVE:To compare the rates of preventive services among PCa survivors five years before and after diagnosis, to men without PCa. DESIGN:Men enrolled in Kaiser Permanente Southern California with newly diagnosed PCa (2002-2008) were matched 1:1 to men without a PCa diagnosis on age, race, and timing of prostate-specific antigen test (N = 31,180). The use of preventive services, including colorectal cancer screening, diabetes tests, lipid panels, and influenza and pneumococcal vaccinations was assessed 5 years before and after diagnosis (or index date for controls). MAIN OUTCOME MEASURES:Relative rates (RRs) of use were calculated for cases and controls separately and compared using Poisson regression, adjusting for comorbidities and outpatient utilization in 2014. RESULTS:Overall, the rates of preventive services were lower among men with PCa vs men without PCa. However, in the 5 years after diagnosis, rates of preventive service use for all services were greater among PCa survivors vs men without PCa (colorectal cancer: RR = 1.05, 95% confidence interval [CI] = 1.01-1.10; lipids: RR = 1.10, 95% CI = 1.08-1.11; hemoglobin A1C: RR = 1.17, 95% CI = 1.14-1.19; glucose: RR = 1.24, 95% CI = 1.23-1.26; influenza vaccine: RR = 1.05, 95% CI = 1.03-1.07; pneumococcal vaccine: RR = 1.03, 95% CI = 0.97-1.09). CONCLUSION:Delivery of preventive care improved after PCa diagnosis, with survivors receiving comparable preventive care to men without PCa during the five years following diagnosis.