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71.
Martin H. Kärcher Cristiano Menezes Denise A. Alves Oliver S. Beveridge Vera-Lucia Imperatriz-Fonseca Francis L. W. Ratnieks 《Die Naturwissenschaften》2013,100(6):571-580
In Melipona quadrifasciata, about 10 % of the females develop into queens, almost all of which are killed. Occasionally, a new queen replaces or supersedes the mother queen or heads a new colony. We investigated virgin queen fate in queenright and queenless colonies to determine the effects of queen behaviour, body mass, nestmate or non-nestmate status, queenright or queenless colony status, and, when queenless, the effect of the time a colony had been queenless, on survival duration and acceptance. None of 220 virgin queens observed in four observation hives ever attacked another virgin queen nor did any of 88 virgin queens introduced into queenright colonies ever attack the resident queen. A new queen was only accepted in a queenless colony. Factors increasing survival duration and acceptance of virgin queens were to emerge from its cell at 2 h of queenlessness, to hide, and to avoid fights with workers. In this way, a virgin queen was more likely to be available when a colony chooses a new queen, 24-48 h after resident queen removal. Running, walking or resting, antennating or trophallaxis, played little or no role, as did the factors body mass or nestmate. “Queen choice” took about 2 h during which time other virgin queens were still being killed by workers. During this agitated process, the bees congregated around the new queen. She inflated her abdomen and some of the workers deposited a substance on internal nest surfaces including the glass lid of the observation hive. 相似文献
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Implicit theories lead individuals to make assumptions about one trait based on their knowledge of another trait. This study experimentally examined Implicit Stress Theory under conditions of high and low performance information. The objective was to test for evidence of Implicit Stress Theory in ratings of effectiveness, commitment, and burnout. Results indicated moderate support for Implicit Stress Theory such that raters evaluated employee burnout and commitment as higher when the employee was perceived to be working under stressful conditions. Interestingly, the data suggested stronger support (based on the proportion of variance explained) for an Implicit Performance Theory such that information regarding good performance was associated with higher levels of commitment and less burnout than poor performance. 相似文献
76.
Mark D. Kilby James Castleman Stephanie Allen Samantha Doyle Denise K. Williams 《黑龙江环境通报》2023,43(11):1472-1476
We report a case of a female fetus born to an unrelated couple with a complex fetal phenotype of a pleural effusion, a cardiac malformation, and syndactyly of the toes. Prenatal exome sequencing identified a variant of uncertain significance in the PORCN gene that was upgraded to likely pathogenic following postnatal clinical examination. The phenotype described in cases with variants in the PORCN gene is often associated with findings that cannot be prospectively diagnosed by ultrasonography. This is the first report of a prenatal phenotype involving a fetal effusion associated with variants in the PORCN gene, with skeletal findings identified later in gestation on ultrasonography. The diagnosis was confirmed on neonatal examination. 相似文献
77.
The objective of assisting with tasks and decisions during incident response is to reduce the risks to victims and rescue personnel while increasing the efficiency of the rescue operation. Handling uncertain information during urban search and rescue (USAR) missions represents additional stress to the decision‐maker. The aim of this study is to identify the decision‐making behaviour of rescuers during USAR missions to pinpoint trapped or buried victims in debris in order to design assistance technologies and decision‐support systems that meet their needs. In 2010, a survey was conducted among 10–15 per cent of all German rescue personnel specialised in search tasks. One of the major results of this survey is that a subjective assessment of the reliability of information available from heterogeneous sources influences the rescuers’ actions and that there is no methodology for decision‐making involving uncertain information. In addition, the study found that compliance with procedures does not require assistance. 相似文献
78.
Biodegradable Polyester-Based Blend Reinforced with Curauá Fiber: Thermal,Mechanical and Biodegradation Behaviour 总被引:1,自引:1,他引:0
Fernanda Harnnecker Derval dos Santos Rosa Denise Maria Lenz 《Journal of Polymers and the Environment》2012,20(1):237-244
Biodegradable composites can be produced by the combination of biodegradable polymers (BP) as matrix and vegetal fibers as
reinforcement. Composites of a commercial biodegradable polymer blend and curauá fibers (loaded at 5, 15 and 20 wt%) were
prepared by melt mixing in a twin-screw extruder. Chemical treatments such as alkali treatment of the fiber and addition of
maleic anhydride grafted polypropylene (MA-g-PP) as coupling agent were performed to promote polymer/fiber interfacial adhesion so that mechanical performance can be
improved. The resulting composites were evaluated through hardness, melt flow index and tensile, flexural and impact strengths
as well as water absorption. Thermal analysis and Fourier transform infrared spectroscopy were also employed to characterize
the composites. The polymer/fiber interface was investigated through scanning electron microscopy analysis. The biodegradability
of composites was evaluated by compost-soil burial test. The addition of curauá fiber promoted an increase in the mechanical
strengths and composites treated with 2 wt% MA-g-PP with 20 wt% curauá fiber showed an increase of nearly 75% in tensile and 56% in flexural strengths besides an improvement
in impact strength with respect to neat polymer blend. Nevertheless, treated composites showed an increase in water absorption
and biodegradation tests showed that the addition of fiber retards degradation time. The retained mass of BP/20 wt% fiber
composite with MA-g-PP and neat BP was 68 and 26%, respectively, after 210 days of degradation test. 相似文献
79.
Salt marshes dominated by Spartina alterniflora and the associated networks of tidal creeks that drain them are characteristic geographical features of southeastern estuaries, important nursery habitat areas, and preferred sites for residential development. As the size of the coastal population increases, so has the number of requests for dock permits. With each new request for a dock permit, public concerns about the cumulative environmental impacts of dock proliferation on the coastal environment have increased. The objective of this particular study was to evaluate the impacts of shading by dock structures on stem densities of S. alterniflora in South Carolina coastal marshes. Shading impacts under individual docks were extrapolated to the tidal creek (local), county, and statewide scales. Dock structures were sampled both under and next to the walkway in the Charleston Harbor area of South Carolina. The density of S. alterniflora under docks was significantly lower than that which occurred next to the docks (i.e., 5 m away) for the short-form, tall-form, and both forms combined. We estimated that shading effects from dock structures in South Carolina decreased the stem density of S. alterniflora by 71%. Dock shading effects were small when evaluated from the perspective of the amount of marsh that occurs within specific tidal creeks (0.03–0.72%), in coastal counties at a maximum dock length (0.01–0.98%), or statewide (0.01–0.13%) at a maximum dock length. However, approximately 7,000 docks have been permitted over the last decade, resulting in a loss of salt marsh equivalent to 60 ha.1Denise M. Sangers present address: Office of Ocean and Coastal Resource Management, South Carolina Department of Health and Environmental Control, 1362 McMillan Avenue, Suite 400 Charleston, South Carolina 29405, USA.
2 A. Frederick Hollands present address: Hollings Marine Laboratory, National Oceanic and Atmospheric Administration, 331 Fort Johnson Road, Charleston, South Carolina 29412, USA. 相似文献
80.
Using the methodology of policy capturing, this research identifies the role that performance, time on the job, commitment of long-term employment and employability play in judgment of termination fairness and employer obligations. Previous research (Rousseau and Anton, 1988) found that seniority and past commitments of long-term employment contributed significantly to judgments of termination fairness and obligation. The present study considered these variables along with performance (past, present and future potential) using 116 participants in human resource management courses. Results indicated that present performance, time on the job, and commitments affect judgments regarding termination fairness and obligation. Past and future performance, however, had no impact on these judgments. Implications of the findings for understanding employer and employee obligations are discussed. 相似文献