233 research outputs found

    An investigation of a controlled free surface effect on fin stabilization of a vessel having a large metacentric height

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    http://www.archive.org/details/investigationofc00kosoU.S. Navy (U.S.N.) authors

    Analysis of Potential Shift to Low-Carbon Urban Travel Modes: A Computational Framework Based on High-Resolution Smartphone Data

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    Given the necessity to understand the modal shift potentials at the level of individual travel times, emissions, and physically active travel distances, there is a need for accurately computing such potentials from disaggregated data collection. Despite significant development in data collection technology, especially by utilizing smartphones, there are limited efforts in developing useful computational frameworks for this purpose. First, development of a computational framework requires longitudinal data collection of revealed travel behavior of individuals. Second, such a computational framework should enable scalable analysis of time-relevant low-carbon travel alternatives in the target region. To this end, this research presents an open-source computational framework, developed to explore the potential for shifting from private car to lower-carbon travel alternatives. In comparison to previous development, our computational framework estimates and illustrates the changes in travel time in relation to the potential reductions in emission and increases in physically active travel, as well as daily weather conditions. The potential usefulness of the framework was evaluated using long-term travel data of around a hundred travelers within the Helsinki Metropolitan Region, Finland. The case study outcomes also suggest that in several cases traveling by public transport or bike would not increase travel time compared to the observed car travel. Based on the case study results, we discuss potentially acceptable travel times for mode shift, and usefulness of the computational framework for decisions regarding transition to sustainable urban mobility systems. Finally, we discuss limitations and lessons learned for data collection and further development of similar computational frameworks.Peer reviewe

    Performance Evaluation of Road Traffic Control Using a Fuzzy Cellular Model

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    In this paper a method is proposed for performance evaluation of road traffic control systems. The method is designed to be implemented in an on-line simulation environment, which enables optimisation of adaptive traffic control strategies. Performance measures are computed using a fuzzy cellular traffic model, formulated as a hybrid system combining cellular automata and fuzzy calculus. Experimental results show that the introduced method allows the performance to be evaluated using imprecise traffic measurements. Moreover, the fuzzy definitions of performance measures are convenient for uncertainty determination in traffic control decisions.Comment: The final publication is available at http://www.springerlink.co

    Orientation toward humans predicts cognitive performance in orang-utans

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    The authors acknowledge the Swiss National Science Foundation and following foundations who have financially supported this project: A. H. Schultz Foundation, Paul Schiller Foundation and the Claraz Foundation in Switzerland and Waldemar von Frenckells Foundation, Ella and Georgh Ehrnrooths Foundation, Otto A. Malms Donationsfond, Nordenskiöld Samfundet and Oskar Öflunds Foundation in Finland.Non-human animals sometimes show marked intraspecific variation in their cognitive abilities that may reflect variation in external inputs and experience during the developmental period. We examined variation in exploration and cognitive performance on a problem-solving task in a large sample of captive orang-utans (Pongo abelii & P. pygmaeus, N = 103) that had experienced different rearing and housing conditions during ontogeny, including human exposure. In addition to measuring exploration and cognitive performance, we also conducted a set of assays of the subjects’ psychological orientation, including reactions towards an unfamiliar human, summarized in the human orientation index (HOI), and towards novel food and objects. Using generalized linear mixed models we found that the HOI, rather than rearing background, best predicted both exploration and problem-solving success. Our results suggest a cascade of processes: human orientation was accompanied by a change in motivation towards problem-solving, expressed in reduced neophobia and increased exploration variety, which led to greater experience, and thus eventually to higher performance in the task. We propose that different experiences with humans caused individuals to vary in curiosity and understanding of the physical problem-solving task. We discuss the implications of these findings for comparative studies of cognitive ability.Publisher PDFPeer reviewe

    ORP2, a cholesterol transporter, regulates angiogenic signaling in endothelial cells

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    https://doi.org/10.1096/fj.202000202ROxysterol-binding protein-related protein 2 (ORP2), a cholesterol-PI(4,5)P(2)countercurrent transporter, was recently identified as a novel regulator of plasma membrane (PM) cholesterol and PI(4,5)P(2)content in HeLa cells. Here, we investigate the role of ORP2 in endothelial cell (EC) cholesterol and PI(4,5)P(2)distribution, angiogenic signaling, and angiogenesis. We show that ORP2 knock-down modifies the distribution of cholesterol accessible to a D4H probe, between late endosomes and the PM. Depletion of ORP2 from ECs inhibits their angiogenic tube formation capacity, alters the gene expression of angiogenic signaling pathways such as VEGFR2, Akt, mTOR, eNOS, and Notch, and reduces EC migration, proliferation, and cell viability. We show that ORP2 regulates the integrity of VEGFR2 at the PM in a cholesterol-dependent manner, the depletion of ORP2 resulting in proteolytic cleavage by matrix metalloproteinases, and reduced activity of VEGFR2 and its downstream signaling. We demonstrate that ORP2 depletion increases the PM PI(4,5)P(2)coincident with altered F-actin morphology, and reduces both VEGFR2 and cholesterol in buoyant raft membranes. Moreover, ORP2 knock-down suppresses the expression of the lipid raft-associated proteins VE-cadherin and caveolin-1. Analysis of the retinal microvasculature in ORP2 knock-out mice generated during this study demonstrates the subtle alterations of morphology characterized by reduced vessel length and increased density of tip cells and perpendicular sprouts. Gene expression changes in the retina suggest disturbance of sterol homeostasis, downregulation of VE-cadherin, and a putative disturbance of Notch signaling. Our data identifies ORP2 as a novel regulator of EC cholesterol and PI(4,5)P(2)homeostasis and cholesterol-dependent angiogenic signaling.Peer reviewe

    Quality of work community and workers' intention to retire

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    Purpose: To study the workers' perception of the quality of work community and its association with intention to retire early, separately among women and men working in Finnish postal service.Methods: A questionnaire survey was sent to all Finnish postal services employees aged >= 50 years in 2016 and 44% (n = 2096) replied to the survey (mean age 56.3, 40% women). Employee's intention to retire before statutory retirement was measured on a scale of 1-5 and dichotomized. The quality of work community was defined by four composite variables: equality at work, flexibility at work, supportive work environment and health or other reason and trichotomized by their tercile values. Odds ratio (ORs) and their 95% confidence intervals (CIs) for associations of quality of work community with intention to retire were calculated separately for men and women using log binomial regression models adjusted for potential confounders.​​​​​​​Results: About one-third of respondents intended to retire early with no significant gender difference in retirement intention. Low equality at work (women OR 2.77, 95% CI 1.60-4.81; men 2.84, 1.80-4.48) and low flexibility at work (women 3.30, 1.94-5.60; men 2.91, 1.88-4.50) was associated with higher likelihood of intention to retire. Among women intention to retire was found less likely due to low supportive work environment (0.52, 0.31-0.89) and among men due to intermediate health or other reason (0.65, 043-0.98). Conclusion: The results highlight the importance of the quality of work community as well as the promotion of work-related health in order to encourage employees to remain at workforce for longer.</p

    Manipulation complexity in primates coevolved with brain size and terrestriality

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    Humans occupy by far the most complex foraging niche of all mammals, built around sophisticated technology, and at the same time exhibit unusually large brains. To examine the evolutionary processes underlying these features, we investigated how manipulation complexity is related to brain size, cognitive test performance, terrestriality, and diet quality in a sample of 36 non-human primate species. We categorized manipulation bouts in food-related contexts into unimanual and bimanual actions, and asynchronous or synchronous hand and finger use, and established levels of manipulative complexity using Guttman scaling. Manipulation categories followed a cumulative ranking. They were particularly high in species that use cognitively challenging food acquisition techniques, such as extractive foraging and tool use. Manipulation complexity was also consistently positively correlated with brain size and cognitive test performance. Terrestriality had a positive effect on this relationship, but diet quality did not affect it. Unlike a previous study on carnivores, we found that, among primates, brain size and complex manipulations to acquire food underwent correlated evolution, which may have been influenced by terrestriality. Accordingly, our results support the idea of an evolutionary feedback loop between manipulation complexity and cognition in the human lineage, which may have been enhanced by increasingly terrestrial habits.Peer reviewe

    The effect of hot days on occupational heat stress in the manufacturing industry: implications for workers' well-being and productivity

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    Climate change is expected to exacerbate heat stress at the workplace in temperate regions, such as Slovenia. It is therefore of paramount importance to study present and future summer heat conditions and analyze the impact of heat on workers. A set of climate indices based on summer mean (Tmean) and maximum (Tmax) air temperatures, such as the number of hot days (HD: Tmax above 30 °C), and Wet Bulb Globe Temperature (WBGT) were used to account for heat conditions in Slovenia at six locations in the period 1981–2010. Observed trends (1961–2011) of Tmean and Tmax in July were positive, being larger in the eastern part of the country. Climate change projections showed an increase up to 4.5 °C for mean temperature and 35 days for HD by the end of the twenty-first century under the high emission scenario. The increase in WBGT was smaller, although sufficiently high to increase the frequency of days with a high risk of heat stress up to an average of a third of the summer days. A case study performed at a Slovenian automobile parts manufacturing plant revealed non-optimal working conditions during summer 2016 (WBGT mainly between 20 and 25 °C). A survey conducted on 400 workers revealed that 96% perceived the temperature conditions as unsuitable, and 56% experienced headaches and fatigue. Given these conditions and climate change projections, the escalating problem of heat is worrisome. The European Commission initiated a program of research within the Horizon 2020 program to develop a heat warning system for European workers and employers, which will incorporate case-specific solutions to mitigate heat stress.The work was supported by the European Union Horizon 2020 Research and Innovation Action (Project number 668786: HEATSHIELD)
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