Dimorphism of Bivalved Arthropod Branchiocaris? Yunnanensis from the Early Cambrian Chengjiang Biota, South China     

WU Yu  FU Dongjing  ZHANG Xingliang  Allison C. DALEY  SHU Degan 《《地质学报》英文版》2016,90(3):818-826

The bivalved arthropod Branchiocaris? yunnanensis Hou, 1987 is redescribed on the basis of new fossil material from the early Cambrian Chengjiang biota, South China. In total, 81 specimens have been examined. The carapace comprises two identical valves, each valve are sub-circular in outline, ranging from 24 mm to 58 mm in length, and from 15 mm to 46 mm in height. The dorsal margin is straight and bears two short cardinal spines. The valve surface is either smooth or ornamented with polygonal reticular structures, which may result from different preservation conditions. Two morphotypes have been recognized based on the presence or absence of a subdorsal swelling of the valve, which is convex dorsolaterally and extends beyond the dorsal margin when it appears. Statistic and ontogenetic analyses show both morphotypes grow isometrically and have the same growth trajectory. Therefore, the two morphotypes are interpreted as dimorphism within the same species. Our results are helpful for investigating the taxonomy and ontogeny of arthropod fossils and suggest that dimorphism might be fairly common in these early arthropods.  相似文献   

Putting the principles of the Sustainable Livelihoods Approach into fisheries development policy and practice   总被引：1，自引：1，他引：1  

Edward H. Allison  Benoit Horemans   《Marine Policy》2006,30(6):757-766

The Sustainable Livelihoods Approach (SLA) combines a conceptual framework with a set of operational principles to provide guidance on policy formulation and development practice. The SLA has been widely used in coastal and fisheries development research and has informed the design of development programmes but experience of operationalising it remains largely undocumented. In the Sustainable Fisheries Livelihoods Programme, which involves 25 West African countries, the SLA has helped to align fisheries policy with wider poverty reduction initiatives and to identify means of contributing to poverty reduction that do not directly increase pressure on fully or over-exploited fish resources.  相似文献   

Sources and sinks of sediment to the Amazon margin: The Amapa coast     

M. A. Allison  C. A. Nittrouer  L. E. C. Faria Jr.  O. M. Silveira  A. C. Mendes 《Geo-Marine Letters》1996,16(1):36-40

Modern and Holocene muddy strata were studied along the shoreline adjacent to the Amazon river mouth using sedimentological, radiochemical, physical, and seismic methods. The present paper is a synthesis of the results, collected during the AmasSeds project, that is used to outline a regional shoreline sediment budget. Erosion of relict Amazon muds in southern Amapa supplies 10⁶ tons yr^–1 to the Amazon advective mud stream. Local rivers are sediment-poor (total suspended discharge ~ 1 × 10⁶ tons yr^–1), but form depositional sandflats on the shoreface downdrift of the river mouths. Mudflat accumulation in northern Amapa sequesters 10⁶–10⁷ tons yr^–1 by tidal-flat aggradation, alongshore mudcape accretion, and sediment trapping by mangroves. The processes temporarily store 1.5 × 10⁸ tons of Amazon mud in January–June.  相似文献   

Evaluation of mussel immune responses as indicators of contamination in San Francisco Bay     

Luengen AC  Friedman CS  Raimondi PT  Flegal AR 《Marine environmental research》2004,57(3):197-212

Several immune parameters were evaluated in two species of mussels (Mytilus californianus and M. galloprovincialis/M. trossulus) as bioindicators of contaminant effects. The mussels were deployed in San Francisco Bay Estuary and a control site at Bodega Marine Laboratory. Assays for phagocytosis and phagocytic index (average number of particles engulfed per hemocyte) were conducted with hemocytes in their own hemolymph-the "Serum" method. The responses were compared with contaminant concentrations in those mussels. For both species, the contaminated South Bay Dumbarton Bridge and Redwood Creek sites had elevated phagocytosis relative to the Bodega control site, indicating contaminant stress. The results also showed that M. californianus had higher percentages of phagocytosis (74%) and a higher phagocytic index (4.6 particles per cell) than those of M. galloprovincialis/M. trossulus (60% phagocytosis and 3.5 particles per cell). As there is a difference in immune response to contaminants, it is suggested that future San Francisco Estuary monitoring should be conducted with endemic M. galloprovincialis/M. trossulus rather than with the currently utilized M. californianus, which is not found in the estuary.  相似文献   

Lateral terminations of salt walls and megaflaps: An example from Gypsum Valley Diapir,Paradox Basin,Colorado, USA     

Frederic O. Escosa  Mark G. Rowan  Katherine A. Giles  Kyle T. Deatrick  Allison M. Mast  Richard P. Langford  Thomas E. Hearon  Eduard Roca 《Basin Research》2019,31(1):191-212

  相似文献   

Integrated estimates of global terrestrial carbon sequestration   总被引：1，自引：0，他引：1  

Allison M. Thomson  R. Csar Izaurralde  Steven J. Smith  Leon E. Clarke 《Global Environmental Change》2008,18(1):192-203

Assessing the contribution of terrestrial carbon sequestration to climate change mitigation requires integration across scientific and disciplinary boundaries. A comprehensive analysis incorporating ecologic, geographic and economic data was used to develop terrestrial carbon sequestration estimates for agricultural soil carbon, reforestation and pasture management. These estimates were applied in the MiniCAM integrated assessment model to evaluate mitigation strategies within policy and technology scenarios aimed at achieving atmospheric greenhouse gas stabilization by 2100. Terrestrial sequestration reaches a peak rate of 0.5–0.7 GtC yr⁻¹ in mid-century with contributions from agricultural soils (0.21 GtC yr⁻¹), reforestation (0.31 GtC yr⁻¹) and pasture (0.15 GtC yr⁻¹). Sequestration rates vary over time and with different technology and policy scenarios. The combined contribution of terrestrial sequestration over the next century ranges from 23 to 41 GtC.  相似文献   

δB, Sr, Mg and B in a modern Porites coral: the relationship between calcification site pH and skeletal chemistry     

Nicola Allison  Adrian A. Finch 《Geochimica et cosmochimica acta》2010,74(6):1790-6360

Sr/Ca, B/Ca, Mg/Ca and δ¹¹B were determined at high spatial resolution across ∼1 year of a modern Hawaiian Porites lobata coral by secondary ion mass spectrometry (SIMS). We observe significant variations in B/Ca, Mg/Ca, Sr/Ca and δ¹¹B over short skeletal distances (nominally equivalent to periods of <20 days). This heterogeneity probably reflects variations in the composition of the extracellular calcifying fluid (ECF) from which the skeleton precipitates. Calcification site pH (total scale) was estimated from skeletal δ¹¹B and ranged from 8.3 to 8.8 (± ∼0.1) with a mean of ∼8.6. Sr/Ca and B/Ca heterogeneity is not simply correlated with calcification site pH, as might be expected if Ca-ATPase activity increases the pH and decreases the Sr/Ca and B(OH)₄⁻/CO₃²⁻ ratios of the ECF. We produced a simple model of the ECF composition and the skeleton deposited from it, over a range of calcium transport and carbonate scenarios, which can account for these observed geochemical variations. The relationship between the pH and Sr/Ca of the ECF is dependent on the concentration of DIC at the calcification site. At higher DIC concentrations the ECF has a high capacity to buffer the [H⁺] changes induced by Ca-ATPase pumping. Conversely, at low DIC concentrations, this buffering capacity is reduced and ECF pH changes more rapidly in response to Ca-ATPase pumping. The absence of a simple correlation between ECF pH and skeletal Sr/Ca implies that calcification occurred under a range of DIC concentrations, reflecting variations in the respiration and photosynthesis of the coral and symbiotic zooxanthellate in the overlying coral tissues. Our observations have important implications for the use of coral skeletons as indicators of palaeo-ocean pH.  相似文献   

Feeling Slow Food: Visceral fieldwork and empathetic research relations in the alternative food movement     

Allison Hayes-Conroy 《Geoforum》2010,41(5):734-742

This paper details the author’s experiments with accessing the visceral realm in research on the food-based social movement, Slow Food (SF). “Visceral” is defined as the bodily realm where feelings, sensations, moods and so on are experienced. Fieldwork methods aimed at participatory co-creation of data through verbal communications in the form of in-depth conversations and group discussions, as well as non-verbal communications in the form of “intentionally designed experiences” and other forms of sensory involvement. Communications centered on understanding how foods and food-based settings elicit feelings and sensations that move and power bodies differently, and specifically how SF guides bodies to be affected by specific foods and environments. The paper details how data were created and recorded, specifically exploring how sensory-based research events were translated to data through the creation of imagined bodily empathies. The paper also discusses the emergence of change-oriented communications that pushed for transformation in SF’s (in)attention to visceral differences, thus demonstrating how visceral research can challenge researchers and participants to critically reflect upon, and perhaps transform, how their own bodies feel (and respond to) the world.  相似文献   

What do near-term observations tell us about long-term developments in greenhouse gas emissions?     

Detlef P. van Vuuren  Jae Edmonds  Steven J. Smith  Kate V. Calvin  Joseph Karas  Mikiko Kainuma  Nebojsa Nakicenovic  Keywan Riahi  Bas J. van Ruijven  Rob Swart  Allison Thomson 《Climatic change》2010,103(3-4):635-642

Long-term scenarios developed by integrated assessment models are used in climate research to provide an indication of plausible long-term emissions of greenhouse gases and other radiatively active substances based on developments in the global energy system, land-use and the emissions associated with these systems. The phenomena that determine these long-term developments (several decades or even centuries) are very different than those that operate on a shorter time-scales (a few years). Nevertheless, in the literature, we still often find direct comparisons between short-term observations and long-term developments that do not take into account the differing dynamics over these time scales. In this letter, we discuss some of the differences between the factors that operate in the short term and those that operate in the long term. We use long-term historical emissions trends to show that short-term observations are very poor indicators of long-term future emissions developments. Based on this, we conclude that the performance of long-term scenarios should be evaluated against the appropriate, corresponding long-term variables and trends. The research community may facilitate this by developing appropriate data sets and protocols that can be used to test the performance of long-term scenarios and the models that produce them.  相似文献   

Seasonal variations of the near surfacelayer parameters over the Antarctic ice sheet in Princess Elizabeth Land,East Antarctica     

谌志刚  卞林根  效存德  陆龙骅 《极地研究(英文版)》2007,18(2):122-134

Analysis of sensible heat flux(Qh),latent heat flux(Qe),Richardson number(Ri),bulk transport coefficient(Cd) and katabatic winds are presented by using the meteorological data in the near surface layer from an automatic weather station(AWS) in Princess Elizabeth Land,East Antarctica ice sheet and the data of corresponding period at Zhongshan station in 2002.It shows that annual mean air temperature at LGB69 is-25.6°C,which is 16.4°C lower than that at Zhongshan,where the elevation is lower and located on the coast.The temperature lapse rate is about 1.0°C/110 m for the initial from coast to inland.The turbulence heat flux at LGB69 displays obvious seasonal variations with the average sensible heat flux-17.9 W/m2 and latent heat flux-0.9 W/m2.The intensity(Qh Qe) of coolling source is-18.8 W/m2 meaning the snow surface layer obtains heat from atmosphere.The near surface atmosphere is near-neutral stratified with bulk transport coefficients(Cd) around 2.8×10-3,and it is near constant when the wind speed higher than 8 m/s.The speed and the frequency of easterly Katabatic winds at LGB69 were higher than that at Zhongshan Station.  相似文献