Testing the consistency of wildlife data types before combining them: the case of camera traps and telemetry.

Wildlife data gathered by different monitoring techniques are often combined to estimate animal density. However, methods to check whether different types of data provide consistent information (i.e., can information from one data type be used to predict responses in the other?) before combining them are lacking. We used generalized linear models and generalized linear mixed-effects models to relate camera trap probabilities for marked animals to independent space use from telemetry relocations using 2 years of data for fishers (Pekania pennanti) as a case study. We evaluated (1) camera trap efficacy by estimating how camera detection probabilities are related to nearby telemetry relocations and (2) whether home range utilization density estimated from telemetry data adequately predicts camera detection probabilities, which would indicate consistency of the two data types. The number of telemetry relocations within 250 and 500 m from camera traps predicted detection probability well. For the same number of relocations, females were more likely to be detected during the first year. During the second year, all fishers were more likely to be detected during the fall/winter season. Models predicting camera detection probability and photo counts solely from telemetry utilization density had the best or nearly best Akaike Information Criterion (AIC), suggesting that telemetry and camera traps provide consistent information on space use. Given the same utilization density, males were more likely to be photo-captured due to larger home ranges and higher movement rates. Although methods that combine data types (spatially explicit capture-recapture) make simple assumptions about home range shapes, it is reasonable to conclude that in our case, camera trap data do reflect space use in a manner consistent with telemetry data. However, differences between the 2 years of data suggest that camera efficacy is not fully consistent across ecological conditions and make the case for integrating other sources of space-use data

Individual differences in delay discounting and nicotine self-administration in rats

Delay discounting—a behavioral measure of impulsivity defined as a tendency to prefer a small, immediate reward over a larger reward delayed in time—has been extensively linked with tobacco smoking. However, the causal direction of this relationship remains unclear. One possibility is that delay discounting may be a marker for an underlying vulnerability to nicotine reinforcement—a possibility which can be isolated using an animal model. In the current study, we investigated whether indifference points derived using an adjustable delay procedure of delay discounting predicted several indices of nicotine reinforcement in rats, including rate of acquisition of nicotine self-administration, break point reached on a progressive ratio schedule of reinforcement, or a shift in the dose-response curve. Stable indifference points were assessed for 63 male Sprague-Dawley rats, and extreme groups of highly impulsive (HI; n=15) and low impulsive (LI; n=11) rats were selected to self-administer nicotine. Rats responded by nose poking for infusions of 0.03 mg/kg nicotine during 1 hour daily sessions. After a 20 session acquisition period, rats completed 3 4-hour progressive ratio sessions, during which the response requirement was increased after each infusion earned. This was followed by 3 1-hour fixed ratio sessions at each of 3 nicotine doses, presented in ascending order (0.015, 0.03, and 0.09 mg/kg). All but one rat (HI group) acquired stable nicotine self-administration; however, no group differences in rate of acquisition were observed. HI and LI rats did not differ in their responses on a progressive ratio schedule or infusions earned at any dose of nicotine, although a significant dose-response effect was observed overall. Indifference points reassessed after self-administration were highly correlated with original indifference points, and mean indifference points for each group at the second assessment did not differ significantly from baseline assessment. These results suggest that delay discounting is a highly reliable measure, but may not be a predictive marker for increased vulnerability to nicotine self-administration in rats

An Investigation of High-Cycle Fatigue Models for Metallic Structures Exhibiting Snap-Through Response

A study is undertaken to develop a methodology for determining the suitability of various high-cycle fatigue models for metallic structures subjected to combined thermal-acoustic loadings. Two features of this problem differentiate it from the fatigue of structures subject to acoustic loading alone. Potentially large mean stresses associated with the thermally pre- and post-buckled states require models capable of handling those conditions. Snap-through motion between multiple post-buckled equilibrium positions introduces very high alternating stress. The thermal-acoustic time history response of a clamped aluminum beam structure with geometric and material nonlinearities is determined via numerical simulation. A cumulative damage model is employed using a rainflow cycle counting scheme and fatigue estimates are made for 2024-T3 aluminum using various non-zero mean fatigue models, including Walker, Morrow, Morrow with true fracture strength, and MMPDS. A baseline zero-mean model is additionally considered. It is shown that for this material, the Walker model produces the most conservative fatigue estimates when the stress response has a tensile mean introduced by geometric nonlinearity, but remains in the linear elastic range. However, when the loading level is sufficiently high to produce plasticity, the response becomes more fully reversed and the baseline, Morrow, and Morrow with true fracture strength models produce the most conservative fatigue estimates

Does Athletic Success Influence Persistence at Higher Education Institutions? New Evidence Using Panel Data

This study examines the relationship between athletic success and student persistence toward a degree. We build an updated panel of National Collegiate Athletic Association (NCAA) Division I institutions and utilize within-institution variation to identify the effects of athletic success. Using a ranking of all institutions, we find that having more successful men\u27s basketball and football teams has a significant positive effect on first-year retention rates. We also find some evidence that improved basketball rankings increase graduation rates, and that success in the NCAA tournament may have a sizable impact on retention. Although the estimated effects are generally modest in scale, we find rather limited evidence of other institutional factors affecting persistence, suggesting that athletics can be one avenue for institutions of higher education to engage and retain students

Anticoagulant rodenticides on our public and community lands: spatial distribution of exposure and poisoning of a rare forest carnivore.

Anticoagulant rodenticide (AR) poisoning has emerged as a significant concern for conservation and management of non-target wildlife. The purpose for these toxicants is to suppress pest populations in agricultural or urban settings. The potential of direct and indirect exposures and illicit use of ARs on public and community forest lands have recently raised concern for fishers (Martes pennanti), a candidate for listing under the federal Endangered Species Act in the Pacific states. In an investigation of threats to fisher population persistence in the two isolated California populations, we investigate the magnitude of this previously undocumented threat to fishers, we tested 58 carcasses for the presence and quantification of ARs, conducted spatial analysis of exposed fishers in an effort to identify potential point sources of AR, and identified fishers that died directly due to AR poisoning. We found 46 of 58 (79%) fishers exposed to an AR with 96% of those individuals having been exposed to one or more second-generation AR compounds. No spatial clustering of AR exposure was detected and the spatial distribution of exposure suggests that AR contamination is widespread within the fisher's range in California, which encompasses mostly public forest and park lands Additionally, we diagnosed four fisher deaths, including a lactating female, that were directly attributed to AR toxicosis and documented the first neonatal or milk transfer of an AR to an altricial fisher kit. These ARs, which some are acutely toxic, pose both a direct mortality or fitness risk to fishers, and a significant indirect risk to these isolated populations. Future research should be directed towards investigating risks to prey populations fishers are dependent on, exposure in other rare forest carnivores, and potential AR point sources such as illegal marijuana cultivation in the range of fishers on California public lands

Role of disclinations in determining the morphology of deformable fluid interfaces

We study the equilibrium shapes of vesicles, with an in-plane nematic order, using a Monte-Carlo scheme and show that highly curved shapes, like tubes and discs, with a striking similarity to the structures engendered by certain curvature sensing peripheral membrane proteins, can be spontaneously generated by anisotropic directional curvature with nematic disclinations playing and important role. We show that the coupling between nematic order and local curvature could lead to like defects moving towards each other and unlike defects moving away, in turn leading to tube formation. Thermally induced defect pair production lead to branched tubular structures. It is also shown that helical arrangement of the membrane tubes, with nematic field spiraling around it, is a dominant soft mode of the system.Comment: 6 Figures; Soft Matter, Advance Article 201

PROCESSING OF SMOKING AND MONETARY REWARDS AMONG CHRONIC SMOKERS: CHARACTERIZATION OF NEURAL RESPONSE, MODERATION BY ABSTINENCE, AND ASSOCIATION WITH SMOKING OUTCOMES

Theoretical models suggest that chronic smoking may be associated with both hypersensitivity to smoking and related cues and hyposensitivity to alternative reinforcers, and that these effects may be more pronounced during deprivation from smoking. However, neural responses to smoking and non-smoking rewards are rarely evaluated within the same paradigm, and current neuroimaging evidence on the effects of deprivation on reward processing is limited. Bias toward smoking reward in lieu of alternative rewards during abstinence could represent a fundamental mechanism contributing to relapse during a quit attempt. In this dissertation, I present a series of analyses to address three primary aims: 1) to characterize the neural response to smoking and non-smoking rewards among chronic smokers within the same paradigm, 2) to determine the impact of deprivation upon the neural response to both reward types, and 3) to evaluate the association between neural responses to both reward types and the choice to smoke in lieu of alternative reinforcement. Smokers each participated in two separate fMRI scans, one after smoking ad libitum and one following 24 hours of abstinence. A rewarded guessing task was conducted during each scan to evaluate BOLD response during anticipation and delivery of both smoking and monetary rewards. Following completion of both scans, smokers engaged in a quit attempt supported by contingency management, during which abstinence from smoking was reinforced with monetary iii reward. Results indicated that smoking and monetary rewards both activated the same reward-related circuitry, including ventral and dorsal striatum, anterior cingulate cortex, medial prefrontal cortex, and bilateral insula. Abstinence from smoking was associated with an increase in anticipatory activation to smoking reward and a parallel decrease in anticipatory activation to monetary reward in the same reward-related regions. Furthermore, preliminary analyses suggested that larger decreases in anticipatory activation to monetary reward in the right caudate were associated with higher likelihood of lapse during contingency management. Collectively, these results suggest that reward processing may be biased toward smoking reward at the expense of alternative rewards during abstinence—a bias which may directly impact smoking behavior during a quit attempt