Predicting the stability of atom-like and molecule-like unit-charge Coulomb three-particle systems

Non-relativistic quantum chemical calculations of the particle mass, m ± 2 , corresponding to the dissociation threshold in a range of Coulomb three-particle systems of the form {m ± 1 m ± 2 m ∓ 3 } , are performed variationally using a series solution method with a Laguerre-based wavefunction. These masses are used to calculate an accurate stability boundary, i.e., the line that separates the stability domain from the instability domains, in a reciprocal mass fraction ternary diagram. This result is compared to a lower bound to the stability domain derived from symmetric systems and reveals the importance of the asymmetric (mass-symmetry breaking) terms in the Hamiltonian at dissociation. A functional fit to the stability boundary data provides a simple analytical expression for calculating the minimum mass of a third particle required for stable binding to a two-particle system, i.e., for predicting the bound state stability of any unit-charge three-particle system

Cause specific mortality and anti-predator behavior in midwestern songbirds

"July 2011"Title from PDF of title page (University of Missouri--Columbia, viewed on May 17, 2012).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dissertation advisor: John FaaborgVita.Predation is a ubiquitous selective pressure that profoundly influences animals on evolutionary and ecological time-scales, but we lack estimates of predator-specific mortality rates for many taxa. We investigated cause-specific mortality of breeding songbird nests in the Midwestern United States and studied the behavior of birds in response to the risk of predation from a diverse suite of predators. Predator-specific mortality rates clarified overall patterns of nest survival, with strong variation in predator-specific rates of predation occurring between songbird species and nest stage. Environmental variables such as nest-site stem density and landscape forest cover also influenced predator-specific rates of predation. Many predators (e.g., corvids, mesopredators, rodents) frequently hypothesized to drive decreased nest survival in fragmented landscapes were not important contributors to overall predation rates in fragmented landscapes. Despite the diversity of species identified depredating songbird nests, parent birds were able to assess an imminent risk of predation and reduced nest visitation rates in an effort to avoid revealing nest locations to predators. Our review of camera use at bird nests demonstrated the variety of technology that is currently available to address a broad suite of study questions.Includes bibliographical reference

Quantum effects of nuclear motion in three-particle diatomic ions

A high accuracy, non-relativistic wavefunction is used to study nuclear motion in the ground state of three-particle {a+1a+2a-3} electronic and muonic molecular systems without assuming the Born Oppenheimer approximation. Intracule densities and center of mass particle densities show that as the mass ratio mai/ma3, i=1,2, becomes smaller, the localisation of the like-charged particles (nuclei) a1 and a2 decreases. A new coordinate system is used to calculate center of mass particle densities for systems where a1≠a2. It is shown that the nuclear motion is strongly correlated and depends on the relative masses of the nuclei a1 and a2 rather than just their absolute mass. The heavier particle is always more localised and, the lighter the partner mass, the greater the localisation. It is shown, for systems with ma1<ma2, that the ratio of (i) the density maximum and (ii) the full width at half maximum (FWHM) of the radial distribution of each nucleus from the center of mass, is directly proportional to the mass ratio of the nuclei: ma1/ma2 for the former and ma2/ma1 for the latter, thus quantifying a quantum effect of nuclear correlation

On the road again: Corridor effects on nesting passerines in Missouri forests [abstract]

Abstract only availableRoads and other linear corridors may have profound ecological consequences. Direct mortality of adult birds by vehicle collisions is well documented, but increased nest predation along road corridors has not been shown in passerines. I tested the hypothesis that nests proximal to unimproved roads (<10 m) suffer greater nest predation than those further from roads (11+ m) due to a predator-corridor effect. Nests from four sites in Missouri were found, monitored, and filmed during the spring and summer of 2007. Roadside shrub-nesting passerines did not experience significantly lower nest success than those nesting far from roads. Acadian Flycatchers experienced significantly higher nest success than did birds of the shrub-nesting guild as a whole. Initial predator identifications are presented

Postfledging habitat selection and survival of Henslow’s Sparrow: management implications for a critical life stage

Conserving populations of species that rely on rare habitat requires that managers understand which habitat characteristics will best support population growth across multiple life stages. For songbirds, management is most often aimed at nesting adult habitat associations. However, habitat that meets adult requirements may not be similarly suited to requirements for other life stages. Henslow’s Sparrow (Centronyx henslowii) is a tallgrass prairie songbird listed as threatened or endangered in 13 states. We examined survival and habitat selection of Henslow’s Sparrow during the postfledging period. During the nesting seasons in 2015 and 2016, we attached radio transmitters to 46 nestlings in a tallgrass prairie and modeled their survival and habitat selection as a function of habitat characteristics. Thirty-five percent of fledglings survived until two weeks postfledge. Survival was negatively associated with areas of sumac (Rhus copallinum) cover, positively associated with years since last burn, and decreased as the breeding season progressed. Snakes were the most common predator of fledglings. Independent fledglings used habitat that was different than that used by adults and dependent fledglings, with habitat used during the independent period having lower litter cover and increased forb cover compared to points used during the dependent period. During the dependent period, points used by fledglings were a mean distance of 40 m (± 11 SD) from the natal nest. Following independence, points used by fledglings were 236 m (± 89 SD) from the natal nest. Henslow’s Sparrow populations may benefit from removal of encroaching sumac in tallgrass prairie, and from consideration of the varying habitats used by the species during different life stages

Population trends of forest birds in Missouri, USA: Comparison of point count data with predictions from the BBS [abstract]

Abstract only availableLong-term population size trends of Neotropical migrants and other forest birds are of primary concern for conservation biologists. The Breeding Bird Survey (BBS) has become an important tool for biologists in estimating population trends, but because surveys are conducted only along roads, its utility for forest interior species may be limited. We analyzed a long term (1991-2006) point count data set from the interior of three forested sites in central Missouri and compared our trend estimates to BBS trends for the state of Missouri. Using a mixed model analysis of variance with year as a fixed effect and point as a random effect, we generated trend estimates for thirteen species. Results/Conclusions Five species (38%) exhibited statistically significant negative trends indicating species decline, four species (31%) exhibited positive trends indicating that populations increased, three species (23%) exhibited no significant trend, and data from one species did not adequately fit the model. Of the nine species with significant trends in our point count data, seven (78%) had trends that were qualitatively similar to those generated from BBS data. However, for both of the species with contrasting trends, model predictions were strongly different. Our results suggest that the accuracy of BBS trends for forest interior birds may be species specific. We hope to strengthen our conclusions by incorporating point count data from other field sites and by controlling for observer effects in future analyses.NSF Undergraduate Mentoring in Environmental Biolog

Effect of Age at Menarche on Anterior Cruciate Ligament Injury Incidence and Anterior Knee Laxity in Collegiate Athletes

Female athletes suffer painful, costly, and career-limiting non-contact anterior cruciate ligament (ACL) injuries more often than males. Previous research suggests that pubertal neuromusculoskeletal development contributes to this sex-bias, but the manner in which variation in pubertal development affects injury risk within females is poorly understood. Age at menarche is a variable, significant pubertal developmental event, signaling the onset of estrogen cycling and affecting musculoskeletal development. Earlier menarche may increase injury risk, possibly by increasing anterior knee laxity through prolonged estrogen exposure. The purpose of this case-control study was to test the primary hypothesis that collegiate athletes with previous ACL injuries have earlier age at menarche than their uninjured peers, and to test the secondary hypothesis that earlier menarche is related to greater anterior knee laxity in injured and uninjured athletes. The study sample consisted of female NCAA Division-I varsity athletes (N=14 injured, N=120 uninjured). Outcome measures included: menstrual history and ACL injury details (injury age, activity at time of injury, contact vs. non-contact), assessed by questionnaire; and anterior knee laxity assessed by KT-1000 arthrometer. Correlation, t-tests, and regression analysis were used to test for associations between age at menarche, injury incidence, and knee laxity. Fourteen athletes reported ≥1 non-contact ACL injury, and had significantly earlier menarche than uninjured athletes (12.6±1.3 y vs. 13.4±1.4 y; P=0.05). Earlier menarche also significantly predicted injury status (Wald c2=7.43; Pb=-1.02±0.37; OR=0.36; 95% CI:0.17-0.75), but was not correlated with anterior knee laxity. Within injured athletes, however, laxity in the unaffected knee was significantly related to time since menarche (r2=0.79, Pr2=0.72,

Stratospheric processes: Observations and interpretation

Explaining the observed ozone trends discussed in an earlier update and predicting future trends requires an understanding of the stratospheric processes that affect ozone. Stratospheric processes occur on both large and small spatial scales and over both long and short periods of time. Because these diverse processes interact with each other, only in rare cases can individual processes be studied by direct observation. Generally the cause and effect relationships for ozone changes were established by comparisons between observations and model simulations. Increasingly, these comparisons rely on the developing, observed relationships among trace gases and dynamical quantities to initialize and constrain the simulations. The goal of this discussion of stratospheric processes is to describe the causes for the observed ozone trends as they are currently understood. At present, we understand with considerable confidence the stratospheric processes responsible for the Antarctic ozone hole but are only beginning to understand the causes of the ozone trends at middle latitudes. Even though the causes of the ozone trends at middle latitudes were not clearly determined, it is likely that they, just as those over Antarctica, involved chlorine and bromine chemistry that was enhanced by heterogeneous processes. This discussion generally presents only an update of the observations that have occurred for stratospheric processes since the last assessment (World Meteorological Organization (WMO), 1990), and is not a complete review of all the new information about stratospheric processes. It begins with an update of the previous assessment of polar stratospheres (WMO, 1990), followed by a discussion on the possible causes for the ozone trends at middle latitudes and on the effects of bromine and of volcanoes

Genetic continuity across a deeply divergent linguistic contact zone in North Maluku, Indonesia

<p>Abstract</p> <p>Background</p> <p>The islands of North Maluku, Indonesia occupy a central position in the major prehistoric dispersal streams that shaped the peoples of Island Southeast Asia and the Pacific. Within this region a linguistic contact zone exists where speakers of Papuan and Austronesian languages reside in close proximity. Here we use population genetic data to assess the extent to which North Maluku populations experienced admixture of Asian genetic material, and whether linguistic boundaries reflect genetic differentiation today.</p> <p>Results</p> <p>Autosomal and X-linked markers reveal overall Asian admixture of 67% in North Maluku, demonstrating a substantial contribution of genetic material into the region from Asia. We observe no evidence of population structure associated with ethnicity or language affiliation.</p> <p>Conclusions</p> <p>Our data support a model of widespread Asian admixture in North Maluku, likely mediated by the expansion of Austronesian-speaking peoples into the region during the mid Holocene. In North Maluku there is no genetic differentiation in terms of Austronesian- versus Papuan-speakers, suggesting extensive gene flow across linguistic boundaries. In a regional context, our results illuminate a major genetic divide at the Molucca Sea, between the islands of Sulawesi and North Maluku. West of this divide, populations exhibit predominantly Asian ancestry, with very little contribution of Papuan genetic material. East of the Molucca Sea, populations show diminished rates of Asian admixture and substantial persistence of Papuan genetic diversity.</p