990 resultados para Mexico -- History.
Resumo:
This review paper provides a brief review on the development of ideas in the fields of the sea level change of the ECS (East China Sea), the history of the Yangtze River entering the sea and paleochannels in the shelf of the ECS since the Last Glacial Maximum (LGM). The paper summarizes two opposite theories about the Yangtze River entering the sea during the LGM. One theory is that the Yangtze River input a lacustrine in the north of Jiangsu province which was defunct in middle Holocene, and the river was once dry. The other was that the Yangtze River still existed and entered into the Okinawa Trough during the LGM, but scholars share different opinions on which course the river ran across and which place the river input the trough. This paper concludes future work is to study the evolution of the Yangtze River and the paleoclimate and the corresponding events as a whole from the view of regional and even global change, and more attention should be paid to the study on mud sediment, the Yangtze River's response to the changes in climate and sea-level, and the channel metamorphosis.
Resumo:
Eolian flux in the Chinese Loess Plateau was reconstructed by measuring the dry bulk density and CaCO3 content of the late Cenozoic loess-paleosol-red clay sequences in the Lingtai profile. Comparison of eolian flux variation between the Lingtai profile and the ODP sites 885/886 in the North Pacific shows a significant wet-dry variability in addition to a gradual drying trend in the dust source regions in interior Asia. Especially, the increase of eolian fluxes from both continental and pelagic eolian sediments indicates a sharp drying of the dust source regions between 3.6 and 2.6 MaBP, which might be attributed to the tectonic uplift of the Tibetan Plateau, which cut down the moisture input to the interior Asia. The average value and variability of eolian flux are higher after 2.6 MaBP than before, which may be related to the Quaternary climatic fluctuations on the glacial-interglacial timescale after the commencement of major Northern Hemisphere Glaciations. The eolian fluxes of the Lingtai profile and Core V21-146 in northwest Pacific show a synchronous variation on the 10(4)-10(5) a timescale, indicating that the flux variations from both continental and marine records are closely correlated to the Quaternary climatic fluctuation forced by the ice volume changes on a global scale.
Resumo:
Ecological and physiological features of the planktonic copepod Calanus sinicus in the southern Yellow Sea in summer were studied to reveal its life history strategy. From the coastal shallow waters to the central part of the southern Yellow Sea, a shift of the stage composition occurs from being dominated by the egg-nauplius stage to being dominated by the fifth copepodite (CV) stage. Most CVs reside in the Yellow Sea Cold Water Mass (YSCWM), where both temperature and food abundance are low. CVs in the YSCWM have longer body lengths, heavier body weights and higher carbon contents than those outside the YSCWM. Onboard incubations show that the development of CVs in the YSCWM is suspended. Energy conservation, development suspension and lack of diel vertical migration (DVM) behavior suggest a diapause status for the CVs in the YSCWM, although vertical distribution patterns indicate the CV individuals are not fully synchronous in physiology and development. This adaptive oversummering strategy would help C. sinicus to live through the warm and food-limited summer in the central part of the southern Yellow Sea; both low temperature and low food supply are necessary for CV to maintain the resting state in the YSCWM. Calanus sinicus exhibits different life history strategies in different regions of the southern Yellow Sea in summer.
Resumo:
Dissolved organic carbon (DOC), stable carbon isotopic (delta(13)C) compositions of DOC and particulate organic carbon (POC), and elemental C/N ratios of POC were measured for samples collected from the lower Mississippi and Atchafalaya rivers and adjacent coastal waters in the northern Gulf of Mexico during the low flow season in June 2000 and high flow season in April 2001. These isotopic and C/N results combined with DOC measurements were used to assess the sources and transport of terrestrial organic matter from the Mississippi and Atchafalaya rivers to the coastal region in the northern Gulf of Mexico. delta(13)C values of both POC (-23.8parts per thousand to -26.8parts per thousand) and DOC (-25.0parts per thousand to -29.0parts per thousand) carried by the two rivers were more depleted than the values measured for the samples collected in the offshore waters. Strong seasonal variations in delta(13)C distributions were observed for both POC and DOC in the surface waters of the region. Fresh water discharge and horizontal mixing played important roles in the distribution and transport of terrestrial POC and DOC offshore. Our results indicate that both POC and DOC exhibited non-conservative behavior during the mixing especially in the mid-salinity range. Based on a simple two end-member mixing model, the comparison of the measured DOC-delta(13)C with the calculated conservative isotopic mixing curve indicated that there was a significant in situ production of marine-derived DOC in the mid- to high-salinity waters consistent with our in situ chlorophyll-a measurements. Our DOC-delta(13)C data suggest that a removal of terrestrial DOC mainly occurred in the high-salinity (>25) waters during the mixing. Our study indicates that the mid- to high- (10-30) salinity range was the most dynamic zone for organic carbon transport and cycling in the Mississippi River estuary. Variability in isotopic and elemental compositions along with variability in DOC and POC concentrations suggest that autochthonous production, bacterial utilization, and photo-oxidation could all play important roles in regulating and removing terrestrial DOC in the northern Gulf of Mexico and further study of these individual processes is warranted. (C) 2004 Elsevier B.V. All rights reserved.
Resumo:
This paper provides basic information on the general ecology and life history cycles of various flatfish species in the Bohai Sea, China. The species studied are Paralichthys olivaceus (Temminck & Schlegel), Cleisthenes herzensteini (Schmidt), Eopsetta grigorjewi (Herzenstein), Verasper variegatus (Temminck & Schlegel), Pleuronichthys cornutus (Temminck & Schlegel), Pseudopleuronectes yokohamae (Gunther), Pseudopleuronectes herzensteini (Jordan & Snyder), Kareius bicoloratus (Basilewsky), Zebrias zebra (Bloch), Cynoglossus semilaevis Gunther, Cynoglossus abbreviatus (Gray) and Cynoglossus joyneri Gunther. Information on reproduction, eggs and larval distribution, growth and adult abundance is presented. Based on the biology and ecology of these flatfish, artificial enhancement of the commercial species in the Bohai Sea is discussed.
Resumo:
An elemental carbon (EC) record, covering the last 420 ka, was reconstructed using chemical oxidation method on a loess and paleosol sequence from the Lingtai section on the Chinese Loess Plateau. The EC record reveals the paleofire history and its relationship with climate and vegetation changes on the Chinese Loess Plateau. Our results show that the EC abundance is generally higher in the paleosols than in the loess layers, showing a glacial/interglacial pattern, which is coincident with biomass changes. This variation pattern indicates that paleofires were intensified when biomass accumulated and climate changed abruptly especially from wet to dry conditions. The EC abundance increases sharply at similar to 130 kaB.P., indicating a dramatic change in the vegetation and climate variation patterns. The occurrence of a peak value with the highest average EC abundance in the Holocene may reflect the occurrence of a major climate event at similar to 6 kaB.P., and may also be partly due to more frequent anthropogenic fire usages. (c) 2007 Elsevier B.V. All rights reserved.
Resumo:
Repeated cycles of retreat and recolonization during the Quaternary ice ages are thought to have greatly influenced current species distributions and their genetic diversity. It remains unclear how this climatic oscillation has affected the distribution of genetic diversity between populations of wind-pollinated conifers in the Qinghai-Tibetan region. In this study, we investigated the within-species genetic diversity and phylogenetic relationships of Picea likiangensis, a dominant forest species in this region using polymorphic DNA (RAPD) markers. Our results suggest that this species has high overall genetic diversity, with 85.42% of loci being polymorphic and an average expected heterozygosity (H (E)) of 0.239. However, there were relatively low levels of polymorphism at population levels and the differences between populations were not significant, with percentages of polymorphic bands (PPB) ranging from 46.88 to 69.76%, Nei's gene diversity (H (E)) from 0.179 to 0.289 and Shannon's indices (Hpop) from 0.267 to 0.421. In accordance with our proposed hypothesis, a high level of genetic differentiation among populations was detected based on Nei's genetic diversity (G (ST) = 0.256) and AMOVA analysis (Phi (st) = 0.236). Gene flow between populations was found to be limited (Nm = 1.4532) and far lower than reported for other conifer species with wide distribution ranges from other regions. No clusters corresponding to three morphological varieties found in the south, north and west, respectively, were detected in either UPGMA or PCO analyses. Our results suggest that this species may have had different refugia during the glacial stages in the southern region and that the northern variety may have multiple origins from these different refugia.
Resumo:
Integrating connectivity patterns into marine ecosystem management is a fundamental step, specially for stock subjected to the combined impacts of human activities (overfishing, habitat degradation, etc.) and climate changes. Thus, management of marine resources must incorporates the spatial scales over which the populations are connected. Notwithstanding, studying these dynamics remains a crucial and hard task and the predictions of the temporal and spatial patterns of these mechanisms are still particularly challenging. This thesis aims to puzzle over the red mullet Mullus barbatus population connectivity in the Western Mediterranean Sea, by implementing a multidisciplinary approach. Otolith sclerochronology, larval dispersal modelling and genetic techniques were gathered in this study. More particularly, this research project focused on early life history stages of red mullet and their role in the characterization of connectivity dynamics. The results show that M. barbatus larval dispersal distances can reach a range of 200 km. The differences in early life traits (i.e. PLD, spawning and settlement dates) observed between various areas of the Western Mediterranean Sea suggest a certain level of larval patchiness, likely due to the occurrence of different spawning pulses during the reproductive period. The dispersal of individuals across distant areas, even not significant in demographic terms, is accountable for the maintenance of the genetic flow among different demes. Fluctuations in the level of exchange among different areas, due to the variability of the source-sink dynamics, could have major implications in the population connectivity patterns. These findings highlight the reliability of combining several approaches and represent a benchmark for the definition of a proper resource management, with considerable engagements in effectively assuring the beneficial effects of the existent and future conservation strategies.
Resumo:
Grattan, J.P. (2006) Aspects of Armageddon: An exploration of the role of volcanic eruptions in human history and civilization, Quaternary International 151, 10-18.
Resumo:
Chapter 1 RAE2008
Resumo:
Kibble, N, ?The Relevance and Admissibility of Prior Sexual History with the Defendant in Sexual Offence Cases? (2001) 32 Cambrian Law Review 27-63 (cited with approval by HL in R v A(2) [2002] AC 45) RAE2008
Resumo:
Judicial Perspectives on the Operation of s.41 and the Relevance and Admissibility of Prior Sexual History Evidence: Four scenarios. N.Kibble. Crim.L.R. 2005 190. RAE2008
Resumo:
Bain, William, 'Are There Any Lessons of History?: The English School and the Activity of Being an Historian', International Politics (2007) 44(5) pp.513-530 RAE2008
Resumo:
Scott, Len, The Cuban Missile Crisis And The Threat Of Nuclear War: Lessons From History (London: Continuum, 2007), pp.xii+222 RAE2008