Saddlepoint approximation for moment generating functions of truncated random variables

We consider the problem of approximating the moment generating function (MGF) of a truncated random variable in terms of the MGF of the underlying (i.e., untruncated) random variable. The purpose of approximating the MGF is to enable the application of saddlepoint approximations to certain distributions determined by truncated random variables. Two important statistical applications are the following: the approximation of certain multivariate cumulative distribution functions; and the approximation of passage time distributions in ion channel models which incorporate time interval omission. We derive two types of representation for the MGF of a truncated random variable. One of these representations is obtained by exponential tilting. The second type of representation, which has two versions, is referred to as an exponential convolution representation. Each representation motivates a different approximation. It turns out that each of the three approximations is extremely accurate in those cases ``to which it is suited.'' Moreover, there is a simple rule of thumb for deciding which approximation to use in a given case, and if this rule is followed, then our numerical and theoretical results indicate that the resulting approximation will be extremely accurate.Comment: Published at http://dx.doi.org/10.1214/009053604000000689 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Long range experimental hydrologic forecasting for the eastern U.S.

We explore a strategy for long-range hydrologic forecasting that uses ensemble climate model forecasts as input to a macroscale hydrologic model to produce runoff and streamflow forecasts at spatial and temporal scales appropriate for water management. Monthly ensemble climate model forecasts produced by the National Centers for Environmental Prediction/Climate Prediction Center global spectral model (GSM) are bias corrected, downscaled to 1/8° horizontal resolution, and disaggregated to a daily time step for input to the Variable Infiltration Capacity hydrologic model. Bias correction is effected by evaluating the GSM ensemble forecast variables as percentiles relative to the GSM model climatology and then extracting the percentiles\u27 associated variable values instead from the observed climatology. The monthly meteorological forecasts are then interpolated to the finer hydrologic model scale, at which a daily signal that preserves the forecast anomaly is imposed through resampling of the historic record. With the resulting monthly runoff and streamflow forecasts for the East Coast and Ohio River basin, we evaluate the bias correction and resampling approaches during the southeastern United States drought from May to August 2000 and also for the El Niño conditions of December 1997 to February 1998. For the summer 2000 study period, persistence in anomalous initial hydrologic states predominates in determining the hydrologic forecasts. In contrast, the El Niño-condition hydrologic forecasts derive direction both from the climate model forecast signal and the antecedent land surface state. From a qualitative standpoint the hydrologic forecasting strategy appears successful in translating climate forecast signals to hydrologic variables of interest for water management

Characterizing Undetected Stellar Companions with Combined Datasets

Binaries play a critical role in the formation, evolution, and fundamental properties of planets, stars, and stellar associations. Observational studies in these areas often include a mix of observations aimed at detecting or ruling out the presence of stellar companions. Rarely can non-detections rule out all possible binary configurations. Here we present MOLUSC, our framework for constraining the range of properties of unseen companions using astrometric, imaging, and velocity information. We showcase the use of MOLUSC on a number of systems, ruling out stellar false positives in the signals of HIP67522b, and DS Tuc Ab. We also demonstrate how MOLUSC could be used to predict the number of missing companions in a stellar sample using the ZEIT sample of young planet hosts. Although our results are not significant, with a larger sample MOLUSC could be used to see if close-in planets are less common in young binary systems, as is seen for their older counterparts.Comment: 19 pages, 10 figures, 4 tables, Accepted to A

Bacteriophages limit the existence conditions for conjugative plasmids

Bacteriophages are a major cause of bacterial mortality and impose strong selection on natural bacterial populations, yet their effects on the dynamics of conjugative plasmids have rarely been tested. We combined experimental evolution, mathematical modeling, and individual-based simulations to explain how the ecological and population genetics effects of bacteriophages upon bacteria interact to determine the dynamics of conjugative plasmids and their persistence. The ecological effects of bacteriophages on bacteria are predicted to limit the existence conditions for conjugative plasmids, preventing persistence under weak selection for plasmid accessory traits. Experiments showed that phages drove faster extinction of plasmids in environments where the plasmid conferred no benefit, but they also revealed more complex effects of phages on plasmid dynamics under these conditions, specifically, the temporary maintenance of plasmids at fixation followed by rapid loss. We hypothesized that the population genetic effects of bacteriophages, specifically, selection for phage resistance mutations, may have caused this. Further mathematical modeling and individual-based simulations supported our hypothesis, showing that conjugative plasmids may hitchhike with phage resistance mutations in the bacterial chromosome

Outcomes of the BOSS Classroom Management Program Among Adults With Intellectual Disabilities

There is a current and growing need for evidence-based practices aimed at improving the social skills of adults with intellectual disabilities (ID). Despite an abundance of research on strategies to improve the social skills of young children with ID, there is limited research on interventions aimed at improving prosocial behaviors of adults with ID. A behavioral skills training approach was used to teach frontline, direct support professionals (DSPs) to implement a classroom management strategy called the Behavioral Opportunities for Social Skills (BOSS) program with adults with ID who lived in the community. The results showed that DSPs’ delivery of behavior-specific praise statements increased after they received training in the BOSS program. Increases in the prosocial behaviors of the adults with ID were also reported after the DSPs were trained. Social validity measures indicated that DSPs liked using the BOSS program, it was easy to implement, and the program was effective. The results of this study suggest that evidence-based social skills interventions developed for children and adolescents, including classroom management strategies, can be effective in improving prosocial behaviors of adults with ID with minimal adaptions

The Role of Emotional Overcontrol in Acceptance of Counselor Training Feedback

Effective feedback is a critical component of counselor training. The degree to which a recipient is able or willing to accept feedback can impact learning and skill development significantly. Recognizing individual trait differences can help the field of counseling understand feedback receptivity in counseling students. This study examined the possible relationship between feedback receptivity and the individual trait of emotional overcontrol. Results indicate that overcontrol accounted for variance in scores on a measure of feedback receptivity in a sample of counseling students, suggesting that individual trait differences meaningfully affect feedback receptivity

Poster 263: Obesity, Blood Pressure and Chronic Low Back Pain

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146960/1/pmr2s118a.pd