257 research outputs found
Increased tolerance to humans among disturbed wildlife.
Human disturbance drives the decline of many species, both directly and indirectly. Nonetheless, some species do particularly well around humans. One mechanism that may explain coexistence is the degree to which a species tolerates human disturbance. Here we provide a comprehensive meta-analysis of birds, mammals and lizards to investigate species tolerance of human disturbance and explore the drivers of this tolerance in birds. We find that, overall, disturbed populations of the three major taxa are more tolerant of human disturbance than less disturbed populations. The best predictors of the direction and magnitude of bird tolerance of human disturbance are the type of disturbed area (urbanized birds are more tolerant than rural or suburban populations) and body mass (large birds are more tolerant than small birds). By identifying specific features associated with tolerance, these results guide evidence-based conservation strategies to predict and manage the impacts of increasing human disturbance on birds
Marginal Probability-Based Integer Handling for CMA-ES Tackling Single-and Multi-Objective Mixed-Integer Black-Box Optimization
This study targets the mixed-integer black-box optimization (MI-BBO) problem
where continuous and integer variables should be optimized simultaneously. The
CMA-ES, our focus in this study, is a population-based stochastic search method
that samples solution candidates from a multivariate Gaussian distribution
(MGD), which shows excellent performance in continuous BBO. The parameters of
MGD, mean and (co)variance, are updated based on the evaluation value of
candidate solutions in the CMA-ES. If the CMA-ES is applied to the MI-BBO with
straightforward discretization, however, the variance corresponding to the
integer variables becomes much smaller than the granularity of the
discretization before reaching the optimal solution, which leads to the
stagnation of the optimization. In particular, when binary variables are
included in the problem, this stagnation more likely occurs because the
granularity of the discretization becomes wider, and the existing integer
handling for the CMA-ES does not address this stagnation. To overcome these
limitations, we propose a simple integer handling for the CMA-ES based on
lower-bounding the marginal probabilities associated with the generation of
integer variables in the MGD. The numerical experiments on the MI-BBO benchmark
problems demonstrate the efficiency and robustness of the proposed method.
Furthermore, in order to demonstrate the generality of the idea of the proposed
method, in addition to the single-objective optimization case, we incorporate
it into multi-objective CMA-ES and verify its performance on bi-objective
mixed-integer benchmark problems.Comment: Camera-ready version for ACM Transactions on Evolutionary Learning
and Optimization (TELO). This paper is an extended version of the work
presented in arXiv:2205.1348
Considerations to Damage Patterns in the Marina District During the Loma Prieta Earthquake Based on Rayleigh Wave Investigation
Rayleigh wave investigation is made in the Marina District to study geotechnical factors controlling the damage patterns in the Loma Prieta earthquake. A portable system has been developed for determining a Rayleigh wave dispersion curve based on the measurements of artificially induced ground vibration or microtremor. Five sites are selected along a line crossing the hydraulic fill zone in which structures and/or buried utilities were significantly damaged. An inverse analysis on the measured dispersion curves results in a cross section of shear wave velocity profiles in the District. Site amplification and liquefaction potential of each site are estimated and discussed based on the Vs-profiles. It is shown that soil liquefaction is likely to have occurred throughout the fill zone, and that the predominant period of ground motions in the zone of structural damage is longer than and closer to the natural period of structures with soft first story than that in the non-damaged zone. These results appear to be consistent with the damage patterns in the District, indicating that the proposed investigation is effective for seismic zonation
The Prevalence and Characteristics of Older Japanese Adults with Polypharmacy, Based on Regionally Representative Health Insurance Claims Data
We aimed to clarify the prevalence of polypharmacy among elderly individuals in Japan. We used the data obtained from a large-scale population-based representative database of health insurance claims in a single prefecture in Japan. We examined all of the outpatient and pharmaceutical health insurance claims for National Health Insurance and those for Late-stage Elderly Health Insurance in Nagasaki Prefecture, Japan between April and June 2016. When two or more claim forms were issued for a patient in a single month, we combined the data and identified the number of prescribed drugs for each person. The definition of polypharmacy is a the prescription of six or more drugs per month. We investigated the prevalence of polypharmacy among the beneficiaries of the two insurance systems. Of the 605,406 beneficiaries of the 2 insurance systems, 121,033 (20.0%) patients with polypharmacy were identified. The prevalence of polypharmacy increased with age, especially among the beneficiaries aged > 85 years, with about half of the beneficiaries having polypharmacy status. About half of the people aged > 85 years in the database had polypharmacy status. When a drug is prescribed to an elderly individual, it is necessary to consider the possibility of polypharmacy-related problems
Effect of current waveform in MIG arc on weld bead formation in plasma-MIG hybrid welding
The version of record of this article, first published in International Journal of Advanced Manufacturing Technology, is available online at Publisher’s website: https://doi.org/10.1007/s00170-024-13684-8.Plasma-metal inert gas (MIG) hybrid welding enables to join thick steel plates in single pass. However, arc coupling occurring between the plasma and MIG arcs disturbs its heat source characteristics, lowering the welding quality. This arc coupling phenomenon is not yet understood due to the complexity. This study aims to clarify the effect of current waveform of arc on weld bead formation according to the arc coupling in plasma-MIG hybrid welding. The metal transfer characteristics and bottom side weld pool were observed for direct current (DC) and pulse-MIG current waveforms. In addition, Ni element was used for visualizing the transport process of high-temperature molten metal provided by MIG welding within the weld pool. From these results, the effects of differences in MIG arc current waveforms on heat and mass transport processes within the weld pool and also on weld bead formation on the bottom side through changes in the occurrence of arc coupling were discussed. As a result, it was clarified that the droplets after detachment from the wire were transferred to the weld pool surface under the wire tip for DC MIG current, while those were transferred along the wire axis to the weld pool surface behind the keyhole for pulse-MIG current. When the droplet was transferred to the weld pool region with the forward flow such as the pulse-MIG current case, the heat was transported to the bottom side together with the counter-clockwise eddy behind the keyhole, strongly contributing to increasing the penetration depth. In the case of pulse-MIG current, the plasma arc is oscillated due to the arc coupling. According to this oscillation, the accumulation of molten metal behind the keyhole is prevented to suppress the humping bead formation. Consequently, pulse-MIG current was found to be suitable for increasing the penetration depth and suppressing humping bead formation on the bottom side comparing with DC MIG current
Experiences of Negotiations for Improving Research Environment and Burnout among Young Physician Researchers in Japan
Physician scientists in Japan are often too busy to be sufficiently involved in research work. This cross-sectional study aimed to investigate their experiences negotiating with their superiors to improve their research environment and determine its relationship with psychological burnout. Among 1790 physician awardees of Grants-in-Aid for Young Scientists in 2014-2015, 490 responded (response rate 27.4%) and 408 were eligible for analysis. Outcome measures included two negotiation experiences: for reduction of clinical duty hours/promotion opportunities and for increased space or equipment/increased research budget. The main explanatory variables were personal, patient-related, and work-related burnout measured by the Copenhagen Burnout Inventory. The percentages of the above-mentioned two types of negotiations were 20-24% in women and 17-20% in men. Multivariable stepwise logistic regression analyses demonstrated that (1) the negotiation for reduction of clinical duty hours/promotion opportunities was significantly associated with physician scientists who had a short amount of weekly research time and high patient-related burnout score, and (2) the negotiation for increased space or equipment/increased research budget was significantly associated with older age, single status, and high personal and patient-related burnout scores. High burnout is related to negotiation experiences among physician researchers in Japan
Development of 1-T Class Force-Balanced Helical Coils Using REBCO Tapes
The authors proposed the concept of the force-balanced helical coils (FBC) using high-temperature superconducting (HTS) tapes as a feasibility option for superconducting magnetic energy storage (SMES). Although the FBC can minimize the mechanical stresses induced by the electromagnetic forces, the FBC has three-dimensional complex shapes of helical winding. Therefore, when the tensile strain and the complex bending strain simultaneously apply to the HTS tapes, the critical current of the HTS coils may decrease irreversibly. The objective of this work is to clarify the critical current property of REBCO tapes depending on the applying complex mechanical strain due to the winding process, the winding configuration and the electromagnetic forces through the development of the HTS-FBC. As a first, design parameters of 1-T class FBC using REBCO tapes and coil winding trajectory were introduced, and the authors discussed the normalized critical current of the HTS-FBC for complex uniaxial strain distribution. The authors also reported a development of a helical winding machine whose motion was optimized to prevent from decreasing the critical current of the HTS tapes during winding process
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