840 research outputs found

    Survival, Habitat Selection, and Body Condition of the Woodchuck (\u3ci\u3eMarmota monax\u3c/i\u3e) across an Urban-rural Gradient

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    Urban-adapter species facultatively exploit human-subsidized resources in the urban and suburban matrix. We used the woodchuck (Marmota monax) to study how aspects of autecology in an urban-adapter can vary across a gradient of urbanization. We captured and monitored woodchucks by radiotelemetry in southern Illinois from summer 2007 to spring 2009. We captured 47 woodchucks (19 adults, 19 yearlings, 8 young-of-the-year) during the active seasons, and implanted radiotransmitters in 17 adults and 3 yearlings (13 F, 7 M). Overall annual survival was estimated to be 0.76 ± 0.12, with three confirmed mortalities during the study period. Survival and home-range size did not vary by % urban landcover in a buffer surrounding an individual\u27s home range. Habitat-selection analyses indicated that rural edge was the highest-ranked habitat at the home-range scale, whereas urban cover (specifically, developed areas with human structures) was most highly ranked at the within-home-range scale. Body condition was negatively related to % urban landcover. Overall, our findings indicated no clear relationship between woodchuck ecology and urbanization level within our study area. However, our data on body condition and adipose composition, although preliminary, suggested a possible mechanism for variation in overwinter survival across the urban-rural gradient

    Correlation potentials for molecular bond dissociation within the self-consistent random phase approximation

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    Self-consistent correlation potentials for H2_2 and LiH for various inter-atomic separations are obtained within the random phase approximation (RPA) of density functional theory. The RPA correlation potential shows a peak at the bond midpoint, which is an exact feature of the true correlation potential, but lacks another exact feature: the step important to preserve integer charge on the atomic fragments in the dissociation limit. An analysis of the RPA energy functional in terms of fractional charge is given which confirms these observations. We find that the RPA misses the derivative discontinuity at odd integer particle numbers but explicitly eliminates the fractional spin error in the exact-exchange functional. The latter finding explains the accurate total energy in the dissociation limit.Comment: 9 pages, 10 figure

    The cognitive/affective distinction of job insecurity: Validation and differential relations

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    Job insecurity as a work-related stressor is well established through three decades of research. It has been related to outcomes such as decreased job satisfaction, organisational commitment and performance as well as increased ill-health and organisational turnover. However, some important conceptual and theoretical issues are still under discussion, with implications for the measurement of the construct. We administered a short version of the measure of job insecurity originally devised by De Witte (2000), which distinguishes between cognitive and affective job insecurity. Data on job satisfaction, commitment, psychological ill-health and emotional exhaustion were also gathered from employees in a variety of South African organisations (N=1925) by means of anonymous surveys. Exploratory and confirmatory factor analyses revealed that the cognitive and affective dimensions of job insecurity could be distinguished in this sample of South African employees, and the two dimensions evidenced adequate reliability. Equivalence analyses showed that the measurement properties of the scale were invariant across various demographic groups. The relationships with outcome variables were investigated by means of correlations and regression analyses. Cognitive job insecurity was predictive of all outcome variables, whereas affective job insecurity primarily played a role for emotional exhaustion. Norm data concerning levels of cognitive and affective job insecurity are presented to guide future South African studies.Key words: Job insecurity, job satisfaction, validation, equivalence analysis, factorial invarianc

    Impact of automated driving systems on road freight transport and electrified propulsion of heavy vehicles

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    The technological barriers to automated driving systems (ADS) are being quickly overcome to deploy on–road vehicles that do not require a human driver on–board. ADS have opened up possibilities to improve mobility, productivity, logistics planning, and energy consumption. However, further enhancements in productivity and energy consumption are required to reach CO2–reduction goals, owing to increased demands on transportation. In particular, in the freight sector, incorporation of automation with electrification can meet necessities of sustainable transport. However, the profitability of battery electric heavy vehicles (BEHVs) remains a concern. This study found that ADS led to profitability of BEHVs, which remained profitable for increased travel ranges by a factor of four compared to that of BEHVs driven by humans. Up to 20% reduction in the total cost of ownership of BEHVs equipped with ADS could be achieved by optimizing the electric propulsion system along with the infrastructure for a given transportation task. In that case, the optimized propulsion system might not be similar to that of a BEHV with a human driver. To obtain the results, the total cost of ownership was minimized numerically for 3072 different transportation scenarios that showed the effects of travel distance, road hilliness, average reference speed, and vehicle size on the incorporated electrification and automation, and compared to that of conventional combustion–powered heavy vehicles

    Compensation profiles among private sector employees in Sweden: Differences in work-related and health-related outcomes

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    How experiences and perceptions of pay and pay setting relate to employees’ job performance, willingness to remain in the organization, and health has been the subject of much debate. Previous research has typically used a variable-centered approach to investigate associations between different pay-related factors and such outcomes. In contrast, we used latent profile analysis to explore combinations of compensation characteristics (pay level, perceived horizontal pay dispersion, and procedural quality, i.e., transactional leadership and procedural pay-setting justice), combining relevant theories on the subject. Based on a nationally representative sample of private sector employees in Sweden (N = 1,146), our study identified six compensation profiles. Our key findings show, first, that higher levels of pay were generally associated with better performance, lower turnover intention, better self-rated health, and lower work-related exhaustion, especially when combined with perceptions of high procedural quality. Second, in terms of perceived horizontal pay dispersion, the results indicate that pay compression may be associated with beneficial outcomes, particularly when combined with high procedural quality. Third, procedural quality was generally associated with favorable work-related and health-related outcomes, although such positive effects may be contingent upon pay level and perceived horizontal pay dispersion. In conclusion, while pay level, perceptions of horizontal pay dispersion, and procedural quality may all matter for employee outcomes, it is important to consider their combinations

    Transportation-mission-based Optimization of Heterogeneous Heavy-vehicle Fleet Including Electrified Propulsion

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    Commercial-vehicle manufacturers design vehicles to operate over a wide range of transportation tasks and driving cycles. However, certain possibilities of reducing emissions, manufacturing and operational costs from end vehicles are neglected if the target range of transportation tasks is narrow and known in advance, especially in case of electrified propulsion. Apart from real-time energy optimization, vehicle hardware can be meticulously tailored to best fit a known transportation task. As proposed in this study, a heterogeneous fleet of heavy-vehicles can be designed in a more cost- and energy-efficient manner, if the coupling between vehicle hardware, transportation mission, and infrastructure is considered during initial conceptual-design stages. To this end, a rather large optimization problem was defined and solved to minimize the total cost of fleet ownership in an integrated manner for a real-world case study. In the said case-study, design variables of optimization problem included mission, recharging infrastructure, loading--unloading scheme, number of vehicles of each type, number of trips, vehicle-loading capacity, selection between conventional, fully electric, and hybrid powertrains, size of internal-combustion engines and electric motors, number of axles being powered, and type and size of battery packs. This study demonstrated that by means of integrated fleet customization, battery-electric heavy-vehicles could strongly compete against their conventional combustion-powered counterparts. Primary focus has been put on optimizing vehicle propulsion, transport mission, infrastructure and fleet size rather than routing

    Unmet challenges in septoplasty-nordic studies from a uniform healthcare and geographical area

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    PurposeNasal septoplasty is one of the most common surgical procedures in otorhinolaryngology and optimising both patient selection and the surgery is a challenge. The Nordic countries have similar public healthcare systems and comparable populations in terms of size. MethodsThis is a review of studies of outcome and predictors related to septoplasty from Denmark, Finland, Norway and Sweden, published during the last decade. The aim of this review was to identify areas in need of further research to meet the challenges of septoplasty in the Nordic countries with reference to international data. ResultsPostoperative patient satisfaction at 6-12 months was reported in around 2/3 of the patients and well in line with international data. Patients with more severe symptoms had a higher chance of improvement. Lack of standardisation in patient selection, surgical methods and skills, and follow up procedures, still makes it difficult to explain the 25% failure rate in septoplasty surgery. ConclusionThis review of the Nordic studies from the last decade shows that septoplasty in general is effective in relieving nasal obstruction. There is a need for studies addressing the standardisation of diagnostic tools and algorithms and the systematic and continuous implementation of follow-up of the surgical results at both departmental and personal level. This includes an awareness of how surgical skills in septoplasty are obtained and maintained.Peer reviewe

    Is Sexual Monomorphism a Predictor of Polygynandry? Evidence from a Social Mammal, the Collared Peccary

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    Sexual dimorphism is common in polygynous species, and there is clear evidence that both intra-sexual competition and female preferences can drive the evolution of large body size in males. In contrast, sexual monomorphism is often argued to reflect a relaxation of male mate competition or an intensification of resource competition among females. Alternatively, it might imply opportunities for females to circumvent or counteract male mate competition in a polygynandrous mating system. We test the prediction that sexual monorphism is associated with polygynandry in the collared peccary (Pecari tajacu, Tayassuidae), a social ungulate closely related to the old-world suids. The genetic mating system in the Tayassuidae is unknown, but its sexual monomorphism presents a striking contrast to the strong size dimorphism found in most Suidae, so that a departure from the polygynous system common in Suidae would be noteworthy. We characterized genetic relationships among adults within herds in three geographically distinct populations, assigned parents to 75 offspring, and tested for skew in individual reproductive success. Parentage assignment data indicated that multiple males sire offspring within a herd, and in the population for which genetic data were most complete, 19% of parentage assignments were potentially sired by extra-herd males. Some litters have multiple sires, and neither males nor females monopolized reproduction, even in small herds. This result supports our prediction and suggests that sexual monomorphism may either select for or be an evolutionary consequence of a promiscuous mating system
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