Parasitism, Adult Emergence, Sex Ratio, and Size of \u3ci\u3eAphidius Colemani\u3c/i\u3e (Hymenoptera: Aphidiidae) on Several Aphid Species

Aphidius colemani Viereck parasitizes several economically important aphid pests of small grain crops including the greenbug, Schizaphis graminum and the Russian wheat aphid, Diuraphis noxia. The ability of A. colemani to switch from S. graminum to several species of aphids common to agricultural and associated non-agricultural ecosystems in the Great Plains, and the effects of host-change on several biological parameters that influence population growth rate were determined. Female A. colemani parasitized and developed to adulthood in nine of 14 aphid species to which they were exposed in the laboratory. All small grain feeding aphids except Sipha flava were parasi­tized. Two sunflower feeding species (Aphis nerii and A. helianthi) and two crucifer feeding species (Lipaphis erysimi and Brevicoryne brassicae) were parasitized, as was the cotton aphid. Aphis gossypii. The average percentage of aphids parasitized differed significantly among host aphid species. as did the percentage of parasitoids surviving from the mummy to the adult stage and the time required for immature development. The sex ratio of adults that enclosed from the various hosts did not differ significantly among species. Dry weights of adult parasitoids differed significantly among host species. Adults from S. graminum weighed most (0.054 mg) while those emerging from A. helianthi weighed least (0.020 mg). Results are discussed in terms of strategies for classical biological control of aphid pests of cereals

Self-Screening Hawking Atmosphere in the Presence of a Bulk Viscosity

The recent theory of 't Hooft [ Nucl. Phys. Suppl. {\bf 68}, 174 (1998)] models the black hole as a system endowed with an envelope of matter that obeys an equation of state in the form $p=(\gamma -1)\rho$, and acts as a source in Einstein's equations. The present paper generalizes the 't Hooft theory so as to take into account a bulk viscosity $\zeta$ in the fluid. It is shown that even a slight positive value of $\zeta$ will suffice to yield complete agreement with the Hawking formula for the entropy of the black hole, if the value of the constant $\gamma$ takes a value that is slightly less than 4/3. The value $\gamma=4/3$ corresponds to a radiation fluid.Comment: 12 pages, LaTeX, no figures, minor extensions of the discussion. To appear in PR

Investigation of local soil resistance on suction caissons at capacity in undrained clay under combined loading

Winkler modelling offers a flexible and computationally efficient framework for estimating suction caisson capacity. However, there is a limited understanding of the local soil resistance acting on caissons at capacity under combined six degrees-of-freedom (6DoF) loading, which is essential for accurately estimating caisson failure envelopes. Furthermore, existing simplified design models for caissons cannot assess capacity under non-planar lateral and moment loading, which is common in offshore wind applications. To address these limitations, this paper presents a comprehensive three-dimensional (3D) finite element analysis (FEA) study, which investigates the local soil resistance acting on the caisson at capacity in undrained clay under combined 6DoF loading. The paper introduces the concept of ‘soil reaction failure envelopes’ to characterise the interactions between soil reactions at capacity. Closed-form formulations are derived to approximate these soil reaction failure envelopes. An elastoplastic Winkler model is then developed, incorporating linear elastic perfectly plastic soil reactions based on these formulations. The results demonstrate that the Winkler model can provide efficient and reasonably accurate estimations of caisson capacity under combined 6DoF loading, even for irregular soil profiles that pose much uncertainty and challenges to existing macro-element models

A systematic framework for formulating convex failure envelopes in multiple loading dimensions

The failure envelope approach is widely used to assess the ultimate capacity of shallow foundations for combined loading, and to develop foundation macro-element models. Failure envelopes are typically determined by fitting appropriate functions to a set of discrete failure load data, determined either experimentally or numerically. However, current procedures to formulate failure envelopes tend to be ad hoc, and the resulting failure envelopes may not have the desirable features of being convex and well-behaved for the entire domain of interest. This paper describes a new systematic framework to determine failure envelopes – based on the use of sum of squares convex polynomials – that are guaranteed to be convex and well-behaved. The framework is demonstrated by applying it to three data sets for failure load combinations (vertical load, horizontal load and moment) for shallow foundations on clay. An example foundation macro-element model based on the proposed framework is also described

Obesity alters the muscle protein synthetic response to nutrition and exercise

Improving the health of skeletal muscle is an important component of obesity treatment. Apart from allowing for physical activity, skeletal muscle tissue is fundamental for the regulation of postprandial macronutrient metabolism, a time period that represents when metabolic derangements are most often observed in adults with obesity. In order for skeletal muscle to retain its capacity for physical activity and macronutrient metabolism, its protein quantity and composition must be maintained through the efficient degradation and resynthesis for proper tissue homeostasis. Life-style behaviors such as increasing physical activity and higher protein diets are front-line treatment strategies to enhance muscle protein remodeling by primarily stimulating protein synthesis rates. However, the muscle of individuals with obesity appears to be resistant to the anabolic action of targeted exercise regimes and protein ingestion when compared to normal-weight adults. This indicates impaired muscle protein remodeling in response to the main anabolic stimuli to human skeletal muscle tissue is contributing to poor muscle health with obesity. Deranged anabolic signaling related to insulin resistance, lipid accumulation, and/or systemic/muscle inflammation are likely at the root of the anabolic resistance of muscle protein synthesis rates with obesity. The purpose of this review is to discuss the impact of protein ingestion and exercise on muscle protein remodeling in people with obesity, and the potential mechanisms underlining anabolic resistance of their muscle

Plankton community composition, organic carbon and thorium-234 particle size distributions, and particle export in the Sargasso Sea

Measurements of plankton community composition (eight planktonic groups), particle size-fractionated (10, 20, 53, 70, and 100-μm Nitex screens) distributions of organic carbon (OC) and 234Th, and particle export of OC and 234Th are reported over a seasonal cycle (2006–2007) from the Bermuda Atlantic Time-Series (BATS) site. Results indicate a convergence of the particle size distributions of OC and 234Th during the winter-spring bloom period (January–March, 2007). The observed convergence of these particle size distributions is directly correlated to the depth-integrated abundance of autotrophic pico-eukaryotes (r = 0.97, P \u3c 0.05) and, to a lesser extent, Synechococcus (r = 0.85, P \u3c 0.14). In addition, there are positive correlations between the sediment trap flux of OC and 234Th at 150 m and the depth-integrated abundance of pico-eukaryotes (r = 0.94, P \u3c 0.06 for OC, and r = 0.98, P \u3c 0.05 for 234Th) and Synechococcus (r = 0.95, P \u3c 0.05 for OC, and r = 0.94, P \u3c 0.06 for 234Th). An implication of these observations and recent modeling studies (Richardson and Jackson, 2007) is that, although small in size, pico-plankton may influence large particle export from the surface waters of the subtropical Atlantic

Qualitative Analysis of Viscous Fluid Cosmological Models satisfying the Israel-Stewart theory of Irreversible Thermodynamics

Isotropic and spatially homogeneous viscous fluid cosmological models are investigated using the truncated Israel-Stewart theory of irreversible thermodynamics to model the bulk viscous pressure. The governing system of differential equations is written in terms of dimensionless variables and a set of dimensionless equations of state is then utilized to complete the system. The resulting dynamical system is analyzed using geometric techniques from dynamical systems theory to find the qualitative behaviour of the Friedmann-Robertson-Walker models with bulk viscosity. In these models there exists a free parameter such that the qualitative behaviour of the models can be quite different (for certain ranges of values of this parameter) from that found in models satisfying the Eckart theory studied previously. In addition, the conditions under which the models inflate are investigated.Comment: 29 pages, 8 Encapsulated PostScript Figures, uses the IOP style file

What Search Data Shows About Americans and Guns During the COVID-19 Crisis

With millions of Americans staying at home across the country during a crisis of intense emotional and economic stress, gun safety advocates have raised concerns about increased risks of unintentional shootings, domestic violence shootings, gun suicides, and city gun violence. Unprecedented spikes in background checks, meanwhile, reflect a dramatic increase in gun purchasing that compounds these risks.Federal background check data, however, fails to capture the full spectrum of ways that people acquire guns, as well as the number of people who are removing guns from gun lockers or other storage. In an effort to cast additional light on issues of firearm access during this stage of the COVID-19 crisis, we used real-time Google search data to gauge interest in buying and cleaning guns across the country

On homothetic cosmological dynamics

We consider the homogeneous and isotropic cosmological fluid dynamics which is compatible with a homothetic, timelike motion, equivalent to an equation of state $\rho + 3P = 0$. By splitting the total pressure $P$ into the sum of an equilibrium part $p$ and a non-equilibrium part $\Pi$, we find that on thermodynamical grounds this split is necessarily given by $p = \rho$ and $\Pi = - (4/3)\rho$, corresponding to a dissipative stiff (Zel'dovich) fluid.Comment: 8 pages, to be published in Class. Quantum Gra