Stress corrosion cracking of titanium alloys at ambient temperature in aqueous solutions

Stress corrosion tests of titanium alloys in distilled and aqueous salt solutions at ambient temperatures employing single edge notched specimen

Stress corrosion cracking of titanium alloys at ambient temperature in aqueous solutions Quarterly progress report, 1 Jan. - 31 Mar. 1967

Stress corrosion cracking of titanium alloys at ambient temperature in aqueous solution

Proceedings of the Tenth Annual Conference on Advances in Cognitive Systems

We hope you will enjoy these proceedings of the Tenth Annual Conference on Advances in Cognitive Systems (ACS). The event was the first hybrid meeting of ACS in is history. It took place virtually via Zoom and physically at George Mason University in Arlington, Virginia, from Saturday, November 19, to Tuesday, November 22, 2022. We are so delighted to be part of continuing this important venue that focuses on the original long-standing goals and challenges of artificial intelligence research. The conference program consisted of 37 papers consisting of ten 30-minute long talks, fifteen 20-minute short talks, twelve posters, three invited talks, two workshops, and a community panel discussion. This year’s Simon Prize Lecture was delivered by Anthony Cohn, Professor of Automated Reasoning at the University of Leeds. More than 200 people attended both in person and virtually. We were fortunate to have the organizational contributions of our local chair, Mihai Boicu of George Mason University, and of the members of the ACS Organizing Committee: Paul Bello, Pat Langley, Sergei Nirenburg, and Matt Klenk. We also thank Mark Burstein, Ken Forbus, Henry Lieberman, Marge McShane, John Laird, and Alexis Kilayko for their many suggestions and contributions. Finally we thank our sponsors, Smart Information Flow Technologies (SIFT) and George Mason University\u27s Institute for Digital Innovation. The latter provided space and technical support that allowed us to produce a high-quality in-person and virtual event. We invite you to visit the Advances in Cognitive Systems YouTube channel (https://www.youtube.com/ @advancesincognitivesystems4184) which has videos of the presentations, invited talks, tutorials, and the panel discussion. -- Jamie C. Macbeth, Leilani Gilpin and Michael T. Cox 13 January 202

Comparison of Two Detailed Models of Aedes aegypti Population Dynamics

The success of control programs for mosquito-­borne diseases can be enhanced by crucial information provided by models of the mosquito populations. Models, however, can differ in their structure, complexity, and biological assumptions, and these differences impact their predictions. Unfortunately, it is typically difficult to determine why two complex models make different predictions because we lack structured side-­by-­side comparisons of models using comparable parameterization. Here, we present a detailed comparison of two complex, spatially explicit, stochastic models of the population dynamics of Aedes aegypti, the main vector of dengue, yellow fever, chikungunya, and Zika viruses. Both models describe the mosquito?s biological and ecological characteristics, but differ in complexity and specific assumptions. We compare the predictions of these models in two selected climatic settings: a tropical and weakly seasonal climate in Iquitos, Peru, and a temperate and strongly seasonal climate in Buenos Aires, Argentina. Both models were calibrated to operate at identical average densities in unperturbedconditions in both settings, by adjusting parameters regulating densities in each model (number of larval development sites and amount of nutritional resources). We show that the models differ in their sensitivityto environmental conditions (temperature and rainfall) and trace differences to specific model assumptions.Temporal dynamics of the Ae. aegypti populations predicted by the two models differ more markedly under strongly seasonal Buenos Aires conditions. We use both models to simulate killing of larvae and/or adults with insecticides in selected areas. We show that predictions of population recovery by the models differ substantially, an effect likely related to model assumptions regarding larval development and (director delayed) density dependence. Our methodical comparison provides important guidance for model improvement by identifying key areas of Ae. aegypti ecology that substantially affect model predictions, and revealing the impact of model assumptions on population dynamics predictions in unperturbed and perturbed conditions.Fil: Legros, Mathieu. University of North Carolina; Estados UnidosFil: Otero, Marcelo Javier. Universidad de Buenos Aires; ArgentinaFil: Romeo Aznar, Victoria Teresa. Universidad de Buenos Aires; ArgentinaFil: Solari, Hernan Gustavo. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Gould, Fred. National Institutes of Health; Estados UnidosFil: Lloyd, Alun L.. National Institutes of Health; Estados Unido

Fishing for flies : testing the efficacy of "stink stations" for promoting blow flies as pollinators in mango orchards

Pollinator communities are composed of diverse groups of insects, with radically different life histories and resource needs. Blow flies are known to visit a variety of economically important crop plants. Larval blow flies develop by feeding on decaying animals. Some fruit growers are known to place carrion on farms during the flowering season to attract adult blow flies (Calliphoridae). However, the efficacy of these “stink stations” has not been tested. We conducted a series of experiments to determine: 1) if stink stations promote the abundance of blow flies in mango orchards (Mangifera indica L.), 2) if any increases in the abundance of flies acts to promote pollination and fruit set in Australian mango orchards. Farms with stink stations had approximately three times more flies than control farms. However, the increased abundance of blow flies did not result in increased fruit set. Although stink stations increased the abundance of blow flies, we found no evidence that their use improves mango yield. This may be due to pollination saturation by a highly abundant native hover fly, Mesembrius bengalensis (Syrphidae), during our study. We hypothesize that stink stations may only be beneficial in years or regions where other pollinators are less abundant

Characterization of the mrgRS locus of the opportunistic pathogen Burkholderia pseudomallei: temperature regulates the expression of a two-component signal transduction system

BACKGROUND: Burkholderia pseudomallei is a saprophyte in tropical environments and an opportunistic human pathogen. This versatility requires a sensing mechanism that allows the bacterium to respond rapidly to altered environmental conditions. We characterized a two-component signal transduction locus from B. pseudomallei 204, mrgR and mrgS, encoding products with extensive homology with response regulators and histidine protein kinases of Escherichia coli, Bordetella pertussis, and Vibrio cholerae. RESULTS: The locus was present and expressed in a variety of B. pseudomallei human and environmental isolates but was absent from other Burkholderia species, B. cepacia, B. cocovenenans, B. plantarii, B. thailandensis, B. vandii, and B. vietnamiensis. A 2128 bp sequence, including the full response regulator mrgR, but not the sensor kinase mrgS, was present in the B. mallei genome. Restriction fragment length polymorphism downstream from mrgRS showed two distinct groups were present among B. pseudomallei isolates. Our analysis of the open reading frames in this region of the genome revealed that transposase and bacteriophage activity may help explain this variation. MrgR and MrgS proteins were expressed in B. pseudomallei 204 cultured at different pH, salinity and temperatures and the expression was substantially reduced at 25°C compared with 37°C or 42°C but was mostly unaffected by pH or salinity, although at 25°C and 0.15% NaCl a small increase in MrgR expression was observed at pH 5. MrgR was recognized by antibodies in convalescent sera pooled from melioidosis patients. CONCLUSION: The results suggest that mrgRS regulates an adaptive response to temperature that may be essential for pathogenesis, particularly during the initial phases of infection. B. pseudomallei and B. mallei are very closely related species that differ in their capacity to adapt to changing environmental conditions. Modifications in this region of the genome may assist our understanding of the reasons for this difference

Branching on multi-aggregated variables

open5siopenGamrath, Gerald; Melchiori, Anna; Berthold, Timo; Gleixner, Ambros M.; Salvagnin, DomenicoGamrath, Gerald; Melchiori, Anna; Berthold, Timo; Gleixner, Ambros M.; Salvagnin, Domenic

Complex population dynamics as a competition between multiple time-scale phenomena

The role of the selection pressure and mutation amplitude on the behavior of a single-species population evolving on a two-dimensional lattice, in a periodically changing environment, is studied both analytically and numerically. The mean-field level of description allows to highlight the delicate interplay between the different time-scale processes in the resulting complex dynamics of the system. We clarify the influence of the amplitude and period of the environmental changes on the critical value of the selection pressure corresponding to a phase-transition "extinct-alive" of the population. However, the intrinsic stochasticity and the dynamically-built in correlations among the individuals, as well as the role of the mutation-induced variety in population's evolution are not appropriately accounted for. A more refined level of description, which is an individual-based one, has to be considered. The inherent fluctuations do not destroy the phase transition "extinct-alive", and the mutation amplitude is strongly influencing the value of the critical selection pressure. The phase diagram in the plane of the population's parameters -- selection and mutation is discussed as a function of the environmental variation characteristics. The differences between a smooth variation of the environment and an abrupt, catastrophic change are also addressesd.Comment: 15 pages, 12 figures. Accepted for publication in Phys. Rev.

Surface Instability of Icicles

Quantitatively-unexplained stationary waves or ridges often encircle icicles. Such waves form when roughly 0.1 mm-thick layers of water flow down the icicle. These waves typically have a wavelength of 1cm approximately independent of external temperature, icicle thickness, and the volumetric rate of water flow. In this paper we show that these waves can not be obtained by naive Mullins-Sekerka instability, but are caused by a quite new surface instability related to the thermal diffusion and hydrodynamic effect of thin water flow.Comment: 11 pages, 5 figures, Late