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21.
Leo J. Fleishman 《Behavioral ecology and sociobiology》1988,22(5):309-316
Summary It is hypothesized that the head movements which make up the introductory portion of the territorial assertion display of Anolis auratus function to draw the gaze of conspecifics. Earlier experiments showed that two features of a motion pattern were critical in making it effective at gaining the attention of an anole: (1) it should consist of high acceleration and velocity, and (2) a Fourier transform of the motion pattern should reveal sinusoidal frequency components distinct from those present in motion patterns commonly present in the environment. The most common source of motion in the environment is windblown vegetation. Motion of vegetation typical of the A. auratus habitat was quantified and analyzed by Fourier transform. Assertion displays of a number of individual lizards were filmed and quantified. It was found that the first 3.6 s of the displays consisted of high acceleration/high velocity movements which contained, at certain sinusoidal frequencies, amplitude several times greater than what was present in the vegetation movement. Thus, motion detection properties of the visual system and movement properties of windblown vegetation combine to influence the physical form of this visual display. 相似文献
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This paper presents a Business Recovery Assessment Framework (BRAF) to help researchers and practitioners design robust, repeatable, and comparable studies of business recovery in various post‐disruption contexts. Studies assessing business recovery without adequately considering the research aims, recovery definitions, and indicators can produce misleading findings. The BRAF is composed of a series of steps that guide the decisions that researchers need to make to ensure: (i) that recovery is indeed being measured; (ii) that the indicators of recovery that are selected align with the objectives of the study and the definition of recovery; and, where necessary, (iii) that appropriate comparative control variables are in place. The paper draws on a large dataset of business surveys collected following the earthquakes in Canterbury, New Zealand, on 4 September 2010 and 22 February 2011 to demonstrate the varied conclusions that different recovery indicators can produce and to justify the need for a systematic approach to business recovery assessments. 相似文献
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Giuseppe Castaldelli Elisa Soana Erica Racchetti Enrica Pierobon Micol Mastrocicco Enrico Tesini Elisa Anna Fano Marco Bartoli 《Environmental management》2013,52(3):567-580
Detailed studies on pollutants genesis, path and transformation are needed in agricultural catchments facing coastal areas. Here, loss of nutrients should be minimized in order to protect valuable aquatic ecosystems from eutrophication phenomena. A soil system N budget was calculated for a lowland coastal area, the Po di Volano basin (Po River Delta, Northern Italy), characterized by extremely flat topography and fine soil texture and bordering a network of lagoon ecosystems. Main features of this area are the scarce relevance of livestock farming, the intense agriculture, mainly sustained by chemical fertilizers, and the developed network of artificial canals with long water residence time. Average nitrogen input exceeds output terms by ~60 kg N ha?1 year?1, a relatively small amount if compared to sub-basins of the same hydrological system. Analysis of dissolved inorganic nitrogen in groundwater suggests limited vertical loss and no accumulation of this element, while a nitrogen mass balance in surface waters indicates a net and significant removal within the watershed. Our data provide multiple evidences of efficient control of the nitrogen excess in this geographical area and we speculate that denitrification in soil and in the secondary drainage system performs this ecosystemic function. Additionally, the significant difference between nitrogen input and nitrogen output loads associated to the irrigation system, which is fed by the N-rich Po River, suggests that this basin metabolizes part of the nitrogen excess produced upstream. The traditionally absent livestock farming practices and consequent low use of manure as fertilizer pose the risk of excess soil mineralization and progressive loss of denitrification capacity in this area. 相似文献
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A lack of resources for post-disaster housing reconstruction significantly limits the prospects for successful recovery. Following the earthquake in Wenchuan, China, in May 2008, housing reconstruction was not immune to resource shortages and price inflation. Difficulties in sourcing materials and labour considerably impeded recovery. This paper provides evidence of the resourcing bottlenecks inherent in the post-Wenchuan earthquake reconstruction process. Its aim is to present an integrated planning framework for managing resources for post-disaster housing rebuilding. The results are drawn from in-field surveys that highlight the areas where stakeholders need to concentrate effort, including revising legislation and policy, enhancing capacity for rebuilding in the construction industry, strengthening the transportation network, restructuring market mechanisms, and incorporating environmental considerations into overall planning. Although the case study presented here is country-specific, it is hoped that the findings provide a basis for future research to identify resourcing constraints and solutions in other disaster contexts. 相似文献
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Many benthic colonial invertebrates have the ability to fuse and form chimeras with compatible colonies. Botryllid ascidians
are model organisms for the study of the evolution of and molecular basis for allorecognition, and fusion rates have been
determined for different populations and species by random sampling and fusion testing between individuals. However, natural
fusion rates over time have not been documented. Nine settlement panels were deployed in Salem Harbor, Massachusetts, USA
and Botrylloides violaceus settlement, growth, and fusion monitored from July to mid-August 2007. Seventy-three percent of the recruits observed fused
with at least one other colony, while 4% neither fused nor were overgrown. Multifused colonies were not observed to grow faster
than single colonies when growth was calculated as increase in size beyond the summation of fused entities; however, they
were significantly larger. These results suggest that larvae settle in clumps of compatible individuals, and that large subtidal
colonies may be the result of high numbers of fusions between compatible colonies. 相似文献
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Liquid aqueous solubility (S(w,L)), octanol/water partition coefficients (K(ow)), liquid vapor pressure (P(v,L)), and Henry's law constants (H(c)) were estimated for 20 methylated naphthalenes ranging from monomethyl to tetramethylnaphthalenes. Chromatographic methods were used for the estimation. Chromatographic retention measurements were conducted for 11 reference compounds and regressions were fit between the retention indices and the physicochemical properties. HPLC octadecylsilyl column with acetonitrile/water eluent was used for the estimation of S(w,L) and K(ow). Two GC columns, HP5-MS and a more hydrophobic HP-1, were tested for the estimation of P(v,L). Measured retention indices for the methylated naphthalenes were entered to the regression equations to calculate the physicochemical properties for these compounds. Literature values, where available, were used to validate the calculated values. The method accurately estimated the physicochemical properties. Estimated S(w,L) and P(v,L) decreased with the number of methyl groups. K(ow) increased with the number of methyl groups. There was no obvious relation between H(c) and the number of methyl groups. Log S(w,L) ranged from 0.885 for 1,2,5,6-tetramethylnaphthalene to 2.269 for 1-methylnaphthalene (mmol/m(3)). Log K(ow) varied from 3.89 for 1-methylnaphthalene to 4.95 for 1,2,5,6-tetramethylnaphthalene. Log P(v,L) ranged from -0.983 for 1,2,5,6-tetramethylnaphthalene to 0.789 for 2-methylnaphthalene (Pa). Log H(c) varied from 1.03 for 1,4,5-trimethylnaphthalene to 1.73 for 2,6-dimethylnaphthalene (Pa m(3)/mol). There were no apparent effects of GC column hydrophobicity on the accuracy of the results. Estimation of S(w,L) and K(ow) based on GC retention indices was not as accurate as with HPLC. Comparison of the estimated values with values predicted by EPIWIN indicated that EPIWIN is useful in giving order-of-magnitude prediction of physicochemical properties. 相似文献
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