A Bayesian Heteroscedastic GLM with Application to fMRI Data with Motion Spikes

We propose a voxel-wise general linear model with autoregressive noise and heteroscedastic noise innovations (GLMH) for analyzing functional magnetic resonance imaging (fMRI) data. The model is analyzed from a Bayesian perspective and has the benefit of automatically down-weighting time points close to motion spikes in a data-driven manner. We develop a highly efficient Markov Chain Monte Carlo (MCMC) algorithm that allows for Bayesian variable selection among the regressors to model both the mean (i.e., the design matrix) and variance. This makes it possible to include a broad range of explanatory variables in both the mean and variance (e.g., time trends, activation stimuli, head motion parameters and their temporal derivatives), and to compute the posterior probability of inclusion from the MCMC output. Variable selection is also applied to the lags in the autoregressive noise process, making it possible to infer the lag order from the data simultaneously with all other model parameters. We use both simulated data and real fMRI data from OpenfMRI to illustrate the importance of proper modeling of heteroscedasticity in fMRI data analysis. Our results show that the GLMH tends to detect more brain activity, compared to its homoscedastic counterpart, by allowing the variance to change over time depending on the degree of head motion

Intestinal Effects of Dietary Betaine in Piglets

The study was conducted to investigate the effects of graded dietary inclusion levels of betaine on ileal and total tract nutrient digestibilities and intestinal bacterial fermentation characteristics in piglets. A total of 8 barrows (BW 7.9 kg) was fitted with simple T-cannulas at the distal ileum. The animals were randomly allocated to 1 of the 4 assay diets with 2 pigs per treatment in 4 repeated measurement periods. The assay diets included a basal diet based on wheat, barley and soybean meal alone, or supplemented with a liquid betaine product at dietary levels of 1.5, 3.0, or 6.0 g betaine kg–1 diet (as–fed). Ileal digestibilities of dry matter (DM) and neutral detergent fiber (NDF) increased both quadratically and linearly (P<0.05), and ileal digestibility of glycine increased linearly as dietary betaine level increased (P<0.05). Moreover, there were linear increases in the concentrations of ileal D–lactic acid (P<0.05), indicating intensified intestinal bacterial activities as dietary betaine level increased. At the fecal level, total tract crude protein (CP) digestibility increased quadratically (P<0.05), and digestibility of amino acids (AA) tended to increase quadratically (P=0.06 to P=0.11), except for proline (P>0.05), as dietary betaine level increased. The increased bacterial degradation of CP and AA in the large intestine coincides with the linear increase (P<0.05) in fecal diaminopimelic acid concentrations, indicating enhanced intestinal bacterial growth with increasing dietary betaine levels. In most cases, there was a response in the variables that were measured up to 3.0 g betaine per kg diet, whereas increasing the betaine level from 3.0 to 6.0 g betaine per kg diet had no additional effect. It can be concluded that dietary betaine stimulates microbial fermentation of fiber in the small intestine, leaving less fermentable fiber to reach the large intestine and therefore, increased microbial degradation of protein in the large intestine may occur. Keywords: piglets, betaine, digestibility, bacterial fermentation, microflor

Betaine, organic acids and inulin do not affect ileal and total tract nutrient digestibility or microbial fermentation in piglets

The study was conducted to investigate the effects of betaine alone or combined with organic acids and inulin on ileal and total tract nutrient digestibilities and intestinal microbial fermentation characteristics in piglets. In total, 24 four-week-old barrows with an average initial body weight of 6.7 kg were used in two consecutive experiments with 12 piglets each. Betaine, organic acids and inulin at a level of 0.2, 0.4 and 0.2%, respectively, or combinations of these supplements were added to the basal diet. The supplementation of betaine, organic acids and inulin or any of their combinations did not affect ileal and total tract nutrient digestibilities. The microbial fermentation products both at the ileal and faecal level were not affected by any of the treatments. In conclusion, combining betaine with organic acids and inulin did not have any associated effects on the variables that were measured

Factors Affecting the Cost of Fissure Sealants: A Dental Insurer's Perspective

The slow adoption of sealants into dental practice is attributed partly to the fact that few prepayment plans pay for sealants. An important concern of insurers is how a sealants benefit will affect premiums. In this analysis, caries rates for various surfaces and teeth, failure rates for both sealants and amalgam restorations, fees and copayments, interest rates, reimbursement policies for replacement and repair, and the passage of time were studied to assess the cost to an insurer of amalgam restorations versus sealants. The results indicate: 1. Sealants as a covered benefit for molars may not cause premiums to increase if fees and copayment levels are properly balanced. If caries in children continues to decline, however, higher premiums may be required if a sealant benefit is provided. 2. Sealants as a covered benefit for bicuspids are likely to require higher premiums. 3. The level of dental caries in the population should be monitored closely, because a further substantial decline in caries prevalence could diminish the economic argument for sealants.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65544/1/j.1752-7325.1986.tb03127.x.pd

The Impact of Improved Oral Health on the Utilization of Dental Services

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153746/1/jddjde017017.pd

Risk Factors for Total Tooth Loss in the United States; Longitudinal Analysis of National Data

The NHANES I Epidemiologic Follow-up Study (NHEFS) of 1982-84 collected longitudinal data from 10,523 individuals initially seen during the first National Health and Nutrition Examination Survey (NHANES I) of 1971-75. Among this additional data was information on the incidence of total tooth loss during the 10 years between the surveys, which could then be added to NHANES I data to identify risk factors. In this analysis, a series of bivariate analyses were carried out, followed by logistic regression analysis to assess the simultaneous effect of major variables. Results showed that 7.4 percent of dentate Americans aged 25-74 at NHANES I became edentulous over the next 10 years. In bivariate analyses, the incidence of edentulism was correlated with baseline measures of lower income and education status, poorer oral health, self-perceptions of poor general health and oral health, absence of a regular dentist, and a lower number of remaining teeth at baseline. No correlation was found with gender and geographic region, nor with self-reported diabetes and arthritis, and age was not a factor when the number of remaining teeth at baseline were taken into account. In a logistic regression model assessing the effect of these variables simultaneously, none of the demographic variables retained significance; the only variable statistically significant in both age groups was the number of teeth remaining at baseline. Other significant variables in younger persons were higher periodontal disease scores, perceived poor dental health, perceived need for extractions, history of smoking, and low ascorbic acid intake. Some of these variables were reflections of negative health behavior and attitudes rather than direct correlates. Principal findings from this study were the importance of early tooth loss in eventual edentulism and the virtual disappearance of gender and age as determinants of total tooth loss.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65639/1/j.1752-7325.1994.tb01173.x.pd

WOODLAND POND SALAMANDER ABUNDANCE IN RELATION TO FOREST MANAGEMENT AND ENVIRONMENTAL CONDITIONS IN NORTHERN WISCONSIN

Woodland ponds are important landscape features that help sustain populations of amphibians that require this aquatic habitat for successful reproduction. Species abundance patterns often reflect site-specific differences in hydrology, physical characteristics, and surrounding vegetation. Large-scale processes such as changing land cover and environmental conditions are other potential drivers influencing amphibian populations in the Upper Midwest, but little information exists on the combined effects of these factors. We used Blue-spotted (Ambystoma laterale Hallowell) and Spotted Salamander (A. maculatum Shaw) monitoring data collected at the same woodland ponds thirteen years apart to determine if changing environmental conditions and vegetation cover in surrounding landscapes influenced salamander movement phenology and abundance. Four woodland ponds in northern Wisconsin were sampled for salamanders in April 1992-1994 and 2005-2007. While Bluespotted Salamanders were more abundant than Spotted Salamanders in all ponds, there was no change in the numbers of either species over the years. However, peak numbers of Blue-spotted Salamanders occurred 11.7 days earlier (range: 9-14 days) in the 2000s compared to the 1990s; Spotted Salamanders occurred 9.5 days earlier (range: 3 - 13 days). Air and water temperatures (April 13- 24) increased, on average, 4.8 oC and 3.7 oC, respectively, between the decades regardless of pond. There were no discernible changes in canopy openness in surrounding forests between decades that would have warmed the water sooner (i.e., more light penetration). Our finding that salamander breeding phenology can vary by roughly 10 days in Wisconsin contributes to growing evidence that amphibian populations have responded to changing climate conditions by shifting life-cycle events. Managers can use this information to adjust monitoring programs and forest management activities in the surrounding landscape to avoid vulnerable amphibian movement periods. Considering direct and indirect stressors such as changing habitat and environmental conditions simultaneously to better understand trends in space and time can help improve monitoring programs for this taxa, which is at major risk of continued declines