Soft-Shelled Turtles (Trionychidae) from the Cenomanian of Uzbekistan

Localities from the Cenomanian of Uzbekistan are the oldest in Middle Asia and Kazakhstan to preserve two broadly sympatric species of trionychid turtle. Material described here comes from multiple Cenomanian formations from the Itemir locality, and from multiple localities in the Cenomanian Khodzhakul Formation. The first taxon from the locality, "Trionyx" cf. kyrgyzensis, has multiple morphological similarities with the older, Early Cretaceous "Trionyx" kyrgyzensis. In contrast, the second taxon, "Trionyx" dissolutus, has multiple similarities with "Trionyx" kansaiensis, one of two species of trionychid found in younger Late Cretaceous localities. "Trionyx" dissolutus bears some superficial resemblance to other trionychid taxa within the clade Plastomenidae because of its highly ossified plastron with a hyoplastral lappet and an epiplastral notch. However, Plastomenidae is diagnosed primarily through characters that are absent or cannot be observed in the available material of "T." dissolutus, and other shared features are plesiomorphic. In addition, "T" dissolutus shares other synapomorphies with Trionychinae. A heavily ossified plastron may be more homoplastric within Trionychidae than has been previously recognized. Finally, we provide an improved understanding of the subtle similarities and differences between several closely related Cretaceous turtle assemblages of Middle Asia and Kazakhstan. (C) 2014 Elsevier Ltd. All rights reserved.National Science Foundation EAR-9804771, 0207004National Geographic Society 5901-97, 6281-98US Civilian Research and Development Foundation RUB1-2860-ST-07Russian Federation NSh-2990.2014.4Russian Foundation for Basic Research 14-04-00416Robert C. Bates Travelling FellowshipGeological Science

Soft-Shelled Turtles (Trionychidae) from the Bissekty formation (Upper Cretaceous: Turonian) of Uzbekistan: Skull-Based Taxa and Probable Skull-Shell Associations

In this paper we describe previously unpublished trionychid turtle material, consisting of skull fragments, from the Late Cretaceous (late Turonian) Bissekty Formation of the Dzharakuduk locality in Uzbekistan. This material is assigned to two taxa: the skull-based Khunnuchelys kizylkumensis Brinkman et al. (1993, Can. J. Earth Sci. 30, 2214-2223) and Trionychini indet. Two specimens which cannot be confidently attributed to these two taxa are considered Trionychidae indet. In addition to these trionychid taxa known from skulls, the Dzharakuduk turtle assemblage includes at least two shell-based taxa, Aspideretoides cf. A. riabinini and "Trionyx" cf. "T." kansaiensis. For this and other Late Cretaceous localities of Middle Asia and Kazakhstan, we suggest the probable skull-shell associations of Khunnuchelys spp. with "Trionyx" kansaiensis-like forms and Trionychini indet. with Aspideretoides-like forms. (C) 2013 Elsevier Ltd. All rights reserved.National Science Foundation EAR-9804771, 0207004National Geographic Society 5901-97, 6281-98US Civilian Research and Development Foundation RUB1-2860-ST-07President of the Russian Federation to the Leading Scientific Schools NSh-6560.2012.4GSA Graduate Student Research GrantGeological Science

Local Fluctuations and Ordering in Liquid and Amorphous Metals

A molecular-dynamics study of the structure and dynamics of monatomic liquids and glasses is presented. The local atomic structure and its development during the quenching process are analyzed in terms of fluctuations of atomic-level stresses and their correlations. This approach extends the basis for the description of the local structure from the usually employed scalar quantity, the local density fluctuation, to a tensorial quantity, the local stress fluctuation. It is shown here that the local stress fluctuations and their spatial and temporal correlations provide a detailed picture of the dynamics of the liquid and of the transition from an ideal fluid to a viscous liquid, and then to a glass. In particular, it is demonstrated that the shear stresses which are spatially uncorrelated at high temperatures become correlated below a temperature, Ts, which is about twice the glass transition temperature. At the same time the dynamic behavior of the liquid, characterized by the diffusivity, viscosity, and phonon states, changes sharply at this temperature. Implications of this apparent structural transition and its origin are then discussed

Soundness of a concurrent collector for actors (extended version)

ORCA is a garbage collection protocol for actor-based programs. Multiple actors may mutate the heap while the collector is running without any dedicated synchronisation. ORCA is applicable to any actor language whose type system prevents data races and which supports causal message delivery. We present a model of ORCA which is parametric to the host language and its type system. We describe the interplay between the host language and the collector. We give invariants preserved by ORCA, and prove its soundness and completeness

Temperatures Influence Susceptibility to Insecticides in Aedes aegypti and Aedes albopictus (Diptera: Culicidae) Mosquitoes

Aedes aegypti and Aedes albopictus (Diptera: Culicidae) are vectors for several arboviruses, including dengue, Zika virus and chikungunya virus. The primary method of controlling these diseases is controlling the vector population, often with insecticides. Insecticide resistance may impact the success of these efforts. We tested the effect of variable temperature exposures on susceptibility to insecticides by exposing adult A. aegypti and A. albopictus to different temperatures and tested their susceptibility to insecticides. We hypothesized that adults maintained at high temperatures would show increased susceptibility to insecticides relative to lower temperatures. Colony mosquitoes were hatched, reared to adulthood and then maintained in three temperature regimes that reflect average seasonal temperatures in the Rio Grande Valley, TX. Susceptibility to permethrin and deltamethrin was assessed using the CDC bottle bioassay method. Overall Aedes albopictus had higher susceptibility to all insecticides than Aedes aegypti. Mosquitoes kept at different temperatures exhibited differential susceptibility to insecticides. Low temperature exposed mosquitoes had decreased susceptibility while high temperature conditions resulted in increased mortality. Our results suggest public health officials must consider temperature effects when controlling mosquitoes with insecticides

Elastic Interfacial Waves in Discrete and Continuous Media

Phonon spectra of bicrystals with relaxed grain-boundary structure display a variety of localized modes including long-wavelength acoustic modes. Continuum solutions for localized waves that incorporate atomic-level elastic properties of the interface via discontinuity relations agree well with the latter modes. In contrast, classical solutions that depend only on bulk elastic properties do not. This demonstrates that the distinct atomic structure of the interface is a controlling factor, and it is shown how local, atomic-level properties can be incorporated into continuum analyses of interfacial phenomena

Generalized stacking fault energy surfaces and dislocation properties of aluminum

We have employed the semidiscrete variational generalized Peierls-Nabarro model to study the dislocation core properties of aluminum. The generalized stacking fault energy surfaces entering the model are calculated by using first-principles Density Functional Theory (DFT) with pseudopotentials and the embedded atom method (EAM). Various core properties, including the core width, splitting behavior, energetics and Peierls stress for different dislocations have been investigated. The correlation between the core energetics and dislocation character has been explored. Our results reveal a simple relationship between the Peierls stress and the ratio between the core width and atomic spacing. The dependence of the core properties on the two methods for calculating the total energy (DFT vs. EAM) has been examined. The EAM can give gross trends for various dislocation properties but fails to predict the finer core structures, which in turn can affect the Peierls stress significantly (about one order of magnitude).Comment: 25 pages, 12 figure

Structure and Strength of Dislocation Junctions: An Atomic Level Analysis

The quasicontinuum method is used to simulate three-dimensional Lomer-Cottrell junctions both in the absence and in the presence of an applied stress. The simulations show that this type of junction is destroyed by an unzipping mechanism in which the dislocations that form the junction are gradually pulled apart along the junction segment. The calculated critical stress needed for breaking the junction is comparable to that predicted by line tension models. The simulations also demonstrate a strong influence of the initial dislocation line directions on the breaking mechanism, an effect that is neglected in the macroscopic treatment of the hardening effect of junctions.Comment: 4 pages, 3 figure

Associations among impulsivity, adverse childhood experiences, and desirability of first sexual experience on substance use and sexual risk taking in justice-involved male adolescents

Adolescent substance use is a serious public health problem (Johnston et al., 2016). Notably in adolescents, adverse childhood experiences including unwanted sexual experiences (Wills et al., 2001; Negriff, Schneiderman, & Trickett, 2015) and impulsive sensation seeking (impulsivity) (Donohew et al., 2000; Fernández-Artamendi et al., 2016) are linked to adolescent substance use and high-risk sexual behaviors. Research also suggests delinquent youths are particularly vulnerable to substance use disorders and sexually risky behaviors (Pinto et al., 2015). Given the health consequences of both prolonged substance abuse and risky sexual behaviors, identifying additional risk factors is critical to help inform interventions for high-risk youth. Data from 314 males, recruited as part of a randomized clinical trial (N = 460) evaluating a theory-based intervention to reduce sexually risky behaviors among justice-involved adolescents, were used for this analysis. Participants completed assessments of adverse childhood experiences, impulsivity, sociosexuality, substance use histories, alcohol/marijuana problems and dependency, and sexual histories. Structural equational modeling (SEM) was used to examine the influence of impulsivity, adverse childhood experiences, sociosexuality, and desirability of first sexual encounter on sexual risk taking and substance use. The final structural equation model including desirability of first sexual encounter, adverse childhood experiences, and impulsivity as exogenous predictors revealed good model fit, χ2(28) = 37.758, p = 0.1031, RMSEA = .033 (90% CI [.000–.058]), CFI = 0.976, WRMR = 0.678. More adverse childhood experiences were associated with higher levels of substance use (β = 0.206, p = .002), greater desirability of first sexual encounter was associated with more sexual risk taking (β = 0.246, p = .007), and higher impulsivity was associated with higher levels of substance use (β = 0.464, p \u3c .001) and more sexual risk taking (β = 0.336, p = .001). Implications for future research and interventions for this vulnerable population are discussed