Home About us Contact
|
Home About us Contact | ||
|
|
||
Millennia
Selected AbstractsTEMPERATURE PROXY RECORDS COVERING THE LAST TWO MILLENNIA: A TABULAR AND VISUAL OVERVIEWGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 1 2009FREDRIK CHARPENTIER LJUNGQVIST ABSTRACT. Proxy data are our only source of knowledge of temperature variability in the period prior to instrumental temperature measurements. Until recently, very few quantitative palaeotemperature records extended back a millennium or more, but the number is now increasing. Here, the first systematic survey is presented, with graphic representations, of most quantitative temperature proxy data records covering the last two millennia that have been published in the peer-reviewed literature. In total, 71 series are presented together with basic essential information on each record. This overview will hopefully assist future palaeoclimatic research by facilitating an orientation among available palaeotemperature records and thus reduce the risk of missing less well-known proxy series. The records show an amplitude between maximum and minimum temperatures during the past two millennia on centennial timescales ranging from c. 0.5 to 4°C and averaging c. 1.5,2°C for both high and low latitudes, although these variations are not always occurring synchronous. Both the Medieval Warm Period, the Little Ice Age and the 20th century warming are clearly visible in most records, whereas the Roman Warm Period and the Dark Age Cold Period are less clearly discernible. [source] Ukrainian Local Governments' Finance on the Threshold of a New Millenium: Will Interbudgetary Reform Meet Public Needs?PUBLIC BUDGETING AND FINANCE, Issue 3 2002Sergii Slukhai Since independence, market,oriented reforms have been undertaken in Ukraine. Yet, intergovernmental relations are obsolete, remaining as they were in the Soviet time. In fact, Ukrainian subcentral governments have no significant discretion in revenues and expenditures. First, the article delivers an overview of the current system of intergovernmental finance in Ukraine. Second, the article reveals some negative trends in Ukrainian local governments' fiscal performance through the late 1990s that made a reform of intergovernmental fiscal arrangements timely. Third, the article analyzes recent reform steps as presented by the recent Budget Code, proposing policy options that could strengthen Ukrainian intergovernmental policy. [source] Civilization in Color: The Multicultural City in Three MillenniaCITY & COMMUNITY, Issue 4 2004Xavier De Souza Briggs How should democratic societies and the cities that propel them respond to increased social diversity? Surprisingly few studies compare cities on their capacity to manage social diversity or offer historical views of the bases for co-existence among identity groups. Studies of this crucial theme that do offer comparative reach are limited to higher-level analyses (e.g., of race and nation making in the modern global order) or partial views (e.g., of economic inequality by race or ethnic politics in contemporary cities). This study, an exercise in theory building, examines three large, history-making, and famously diverse cities that relied on distinct designs for society to accommodate diversity: ancient Rome, medieval Cordoba, and contemporary Los Angeles. Comparisons across such huge spans of time and major culture shifts yield lessons obscured in current debates over inequality, multiculturalism, or the need for tolerance. Three of the most important lessons relate to the power of integrative societal projects much larger than cities; the co-existence throughout history of separatism or cultural mosaic patterns alongside active cross-cultural exchange and hybridization; and the need to bound pluralistic ideals within a strong, locally viable public order. In earlier periods of history, autocracy provided such order for standout pluralist cities and the civilizations they led. Come, come whoever you are. Ours is not a caravan of despair. ,Rumi, 13th-century Persian poet [source] The emptiness of zero: representations of loss, absence, anxiety and desire in the late twentieth centuryCRITICAL QUARTERLY, Issue 1 2004Kathy Smith As the new millenium approached, the anxiety which this moment generated found resonance in various cultural representations, and the appearance of spectral imagery seemed to indicate an anxiety about subjectivity, and about its fragmentation or complete loss. Unable to comtemplate a state beyond this loss, there came into being a crisis in subjectivity itself, and the existence of the destabilized millenium subject. This subject approached the moment by both fixating on the threshold and by disavowing what lay beyond. These strategies, and the underlying anxiety which brought them into existence, were resonated through many of the cultural representations of the time. This paper argues that it is through nachträglichkeit - a 'making sense' in retrospect of earlier disparate experiences - that we can begin to examine, contextualise and account for the phenomenon of 'millenium frenzy' which came about at the end of 1999. It constructs a reading of this moment, and of two particular filmic representations which resonate the concerns of the time, examining in the process how - from a psychoanalytic perspective - culture might be understood through its representations, and how these representations can be understood through culture. [source] Clinical trends in atrial fibrillation at the turn of the milleniumJOURNAL OF INTERNAL MEDICINE, Issue 5 2001I. Savelieva First page of article [source] Phylogenetic biogeography and taxonomy of disjunctly distributed bryophytesJOURNAL OF SYSTEMATICS EVOLUTION, Issue 5 2009Jochen HEINRICHS Abstract, More than 200 research papers on the molecular phylogeny and phylogenetic biogeography of bryophytes have been published since the beginning of this millenium. These papers corroborated assumptions of a complex genetic structure of morphologically circumscribed bryophytes, and raised reservations against many morphologically justified species concepts, especially within the mosses. However, many molecular studies allowed for corrections and modifications of morphological classification schemes. Several studies reported that the phylogenetic structure of disjunctly distributed bryophyte species reflects their geographical ranges rather than morphological disparities. Molecular data led to new appraisals of distribution ranges and allowed for the reconstruction of refugia and migration routes. Intercontinental ranges of bryophytes are often caused by dispersal rather than geographical vicariance. Many distribution patterns of disjunct bryophytes are likely formed by processes such as short distance dispersal, rare long distance dispersal events, extinction, recolonization and diversification. [source] Neurogastroenterology and motility: new millenium, new horizonsNEUROGASTROENTEROLOGY & MOTILITY, Issue 3 2001Article first published online: 7 JUL 200 No abstract is available for this article. [source] Flexibility: A Concept AnalysisNURSING FORUM, Issue 1 2000Michele August-Brady RN Flexibility is a quality that is deemed essential for nursing as the healthcare environment escalates into greater complexity. The word "flexibility" appears in nursing literature addressing the need to prepare for the next millenium, yet the concept of flexibility is rarely defined. Other disciplines, such as engineering, have struggled for years and continue to struggle to achieve conceptual clarity with regard to flexibility. A concept analysis using Rodgers' evolutionary method was undertaken to understand the meaning of flexibility. [source] Beneficial lactobacilli in food and feed: long-term use, biodiversity and proposals for specific and realistic safety assessmentsFEMS MICROBIOLOGY REVIEWS, Issue 4 2006Marion Bernardeau Abstract Lactobacilli have played a crucial role in the production of fermented products for millennia. Their probiotic effects have recently been studied and used in new products. Isolated cases of lactobacillemia have been reported in at-risk populations, but lactobacilli present an essentially negligible biological risk. We analyzed the current European guidelines for safety assessment in food/feed and conclude that they are not relevant for the Lactobacillus genus. We propose new specific guidelines, beginning by granting a ,long-standing presumption of safety' status to Lactobacillus genus based on its long history of safe use. Then, based on the available body of knowledge and intended use, only such tests as are useful will be necessary before attributing ,qualified presumption of safety' status. [source] Fire-cracked rock features on sandy landforms in the Northern Rocky Mountains: Toward establishing reliable frames of reference for assessing site integrityGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 5 2007Alston V. Thoms In cool coniferous forest settings of the Northern Rocky Mountains, well-preserved fire-cracked rock (FCR) features within 30 cm of the surface on ostensibly stable, sandy upland landforms date to the last six millennia. Isolated FCR and artifacts sometimes extend a meter or more below surface, which is suggestive of in situ burial. A paucity of intact features in the lower solum, however, is consistent with the downward migration of deeply buried artifacts by biomechanical processes, especially floralturbation. Moreover, an absence of credible sediment source areas usually precludes colluvial deposition, and results of grain-size analysis reported herein are inconsistent with eolian deposition. Site disarticulation rates tend to be faster on landforms in warmer forested regions of south-central North America, given that most intact FCR features there date only to the last two millennia. The very presence of millennia-old FCR features in these diverse settings, however, is a testament to their durability and utility as measures of site integrity. © 2007 Wiley Periodicals, Inc. [source] A simulation of the hydrothermal response to the Chesapeake Bay bolide impactGEOFLUIDS (ELECTRONIC), Issue 3 2005W. E. SANFORD Abstract Groundwater more saline than seawater has been discovered in the tsunami breccia of the Chesapeake Bay Impact Crater. One hypothesis for the origin of this brine is that it may be a liquid residual following steam separation in a hydrothermal system that evolved following the impact. Initial scoping calculations have demonstrated that it is feasible such a residual brine could have remained in the crater for the 35 million years since impact. Numerical simulations have been conducted using the code HYDROTHERM to test whether or not conditions were suitable in the millennia following the impact for the development of a steam phase in the hydrothermal system. Hydraulic and thermal parameters were estimated for the bedrock underlying the crater and the tsunami breccia that fills the crater. Simulations at three different breccia permeabilities suggest that the type of hydrothermal system that might have developed would have been very sensitive to the permeability. A relatively low breccia permeability (1 × 10,16 m2) results in a system partitioned into a shallow water phase and a deeper superheated steam phase. A moderate breccia permeability (1 × 10,15 m2) results in a system with regionally extensive multiphase conditions. A relatively high breccia permeability (1 × 10,14 m2) results in a system dominated by warm-water convection cells. The permeability of the crater breccia could have had any of these values at given depths and times during the hydrothermal system evolution as the sediments compacted. The simulations were not able to take into account transient permeability conditions, or equations of state that account for the salt content of seawater. Results suggest, however, that it is likely that steam conditions existed at some time in the system following impact, providing additional evidence that is consistent with a hydrothermal origin for the crater brine. [source] TEMPERATURE PROXY RECORDS COVERING THE LAST TWO MILLENNIA: A TABULAR AND VISUAL OVERVIEWGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 1 2009FREDRIK CHARPENTIER LJUNGQVIST ABSTRACT. Proxy data are our only source of knowledge of temperature variability in the period prior to instrumental temperature measurements. Until recently, very few quantitative palaeotemperature records extended back a millennium or more, but the number is now increasing. Here, the first systematic survey is presented, with graphic representations, of most quantitative temperature proxy data records covering the last two millennia that have been published in the peer-reviewed literature. In total, 71 series are presented together with basic essential information on each record. This overview will hopefully assist future palaeoclimatic research by facilitating an orientation among available palaeotemperature records and thus reduce the risk of missing less well-known proxy series. The records show an amplitude between maximum and minimum temperatures during the past two millennia on centennial timescales ranging from c. 0.5 to 4°C and averaging c. 1.5,2°C for both high and low latitudes, although these variations are not always occurring synchronous. Both the Medieval Warm Period, the Little Ice Age and the 20th century warming are clearly visible in most records, whereas the Roman Warm Period and the Dark Age Cold Period are less clearly discernible. [source] Drivers of Unsustainable Land Use in the Semi-Arid Khabur River Basin, SyriaGEOGRAPHICAL RESEARCH, Issue 1 2009FRANK HOLE Abstract The semi-arid zone of Southwest Asia, known as the Fertile Crescent, is under unprecedented stress because of agricultural development. Where rain-fed agriculture and transhumant herding had prevailed over ten millennia, today intensive cultivation with irrigation threatens future sustainability. A number of interconnected, but uncoordinated drivers of change combine to shape the landscape and its future, and their changes make it hard to anticipate future requirements and opportunities, as well as to implement policies, whether by local stakeholders or at the national level. Among the factors that comprise the socio-natural systems are (1) climate, (2) water and soil resources, (3) history of land use, (4) social, economic and political factors, (5) infrastructural developments (6) interstate impacts, and (7) legacies of the past. The example of the Khabur River drainage in northeastern Syria shows the dynamic interplay among these factors over the past 70 years, with implications for the way future policies and practices are developed. [source] The evolution of, and revolution in, land surface schemes designed for climate modelsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 5 2003A. J. Pitman Abstract The land surface is a key component of climate models. It controls the partitioning of available energy at the surface between sensible and latent heat, and it controls the partitioning of available water between evaporation and runoff. The land surface is also the location of the terrestrial carbon sink. Evidence is increasing that the influence of the land surface is significant on climate and that changes in the land surface can influence regional- to global-scale climate on time scales from days to millennia. Further, there is now a suggestion that the terrestrial carbon sink may decrease as global temperatures increase as a consequence of rising CO2 levels. This paper provides the theoretical background that explains why the land surface should play a central role in climate. It also provides evidence, sourced from climate model experiments, that the land surface is of central importance. This paper then reviews the development of land surface models designed for climate models from the early, very simple models through to recent efforts, which include a coupling of biophysical processes to represent carbon exchange. It is pointed out that significant problems remain to be addressed, including the difficulties in parameterizing hydrological processes, root processes, sub-grid-scale heterogeneity and biogeochemical cycles. It is argued that continued development of land surface models requires more multidisciplinary efforts by scientists with a wide range of skills. However, it is also argued that the framework is now in place within the international community to build and maintain the latest generation of land surface models. Further, there should be considerable optimism that consolidating the recent rapid advances in land surface modelling will enhance our capability to simulate the impacts of land-cover change and the impacts of increasing CO2 on the global and regional environment. Copyright © 2003 Royal Meteorological Society [source] Two millennia of male stature development and population health and wealth in the Low CountriesINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 4 2005G. J. R. MaatArticle first published online: 5 AUG 200 Abstract This paper offers a review of shifts in average male stature and their relationship with health and wealth in the Low Countries from AD 50 to 1997. Twenty-one population samples were studied to cover the full time span. To make data compatible, so-called ,virtual statures' were used, i.e. the statures which adult males were supposed to have had at the end of their growth period, before they started shrinking by ageing. Original data were extracted from ,in situ measured statures', ,calculated statures' and ,corrected cadaveric statures'. If possible, maximum femoral lengths were also collected from the same population samples to check whether trends in stature development were in agreement with raw skeletal data. A long phase of stature decrease from ca. 176,cm to 166,cm, a so-called ,negative secular trend', was noticed from the Roman Period up to and including the first half of the 19th century. This was followed by a sharp and still ongoing increase in stature to 184,cm, a typical ,positive secular trend', from the second half of the 19th century to the present time. General shifts in stature and ,outliers' illustrative for the process are viewed in the context of socio-economic, demographic, health and nutritional factors. Copyright © 2005 John Wiley & Sons, Ltd. [source] ORIGINAL ARTICLE: Extinction of the autochthonous small mammals of Mallorca (Gymnesic Islands, Western Mediterranean) and its ecological consequencesJOURNAL OF BIOGEOGRAPHY, Issue 6 2008Pere Bover Abstract Aim, To investigate the chronology, causes and consequences of the extinction of the autochthonous Pleistocene small mammals of Mallorca. Location, Mallorca (Gymnesic Islands, Balearics, Western Mediterranean). Methods, We have obtained the first direct 14C ages from the bone collagen of selected samples of two extinct endemic small mammals from Mallorca: the Balearic dormouse, Eliomys morpheus (Rodentia: Myoxidae) and the Balearic shrew, Asoriculus hidalgoi (Soricomorpha: Soricidae). We also present evidence for the absence of both endemics from the earliest Mallorcan archaeological sites and for the introduction of the garden dormouse, Eliomys quercinus, and the wood mouse, Apodemus sylvaticus. Combined information from direct dating of bone collagen of E. quercinus and A. sylvaticus and from cultural associations provides an adequate framework to establish the chronology of the faunal change and to compare it with the chronological information available on climatic change and the first arrival of humans on the islands. Results, The chronological record includes the latest evidence available for the survival of endemic species and the earliest introduction of small mammals into Mallorca. We present ,uncertainty periods for extinction' (UPEs) of both endemic mammals based on the chronology of their last occurrence and on the inferred timing of their extinction (restricted UPEs). Main conclusions, Possible causes for the extinction of autochthonous small mammals on Mallorca are discussed. Once we have discarded climatic causes, predation by invasive species, competition with newcomers and habitat deterioration, the introduction of diseases emerges as the most reasonable explanation for these extinctions. Based on the identification of changes in keystone species in Mallorcan ecosystems, we propose a tentative schedule of key ecological changes that have taken place over the past 5 millennia. [source] From bobolinks to bears: interjecting geographical history into ecological studies, environmental interpretation, and conservation planningJOURNAL OF BIOGEOGRAPHY, Issue 1 2000David R. Foster Abstract In these days of supercomputer-based global climate models, large ecosystem experiments including Biosphere II, and aircraft-borne sensors of ozone holes it is often overlooked that many fundamental insights into ecological processes and major environmental issues come not through reductionist or high-tech studies of modern conditions but from thoughtful consideration of nature's history. In fact, it is foolhardy to make any ecological interpretation of modern landscapes or environments or to formulate policy in conservation or natural resource management without an historical context that extends back decades, at least, but preferably centuries or millennia. Oftentimes, the ecological and conservation communities, in their search for more detail on the present and simulation of the future, appear to have forgotten the value of a deep historical perspective in research and application. However, the willingness of the geographical sciences to embrace broad temporal and spatial perspectives and to consider cultural as well as natural processes is worth emulating as we address environmental subjects in the new millennium. [source] The use of chronosequences in studies of ecological succession and soil developmentJOURNAL OF ECOLOGY, Issue 4 2010Lawrence R. Walker Summary 1.,Chronosequences and associated space-for-time substitutions are an important and often necessary tool for studying temporal dynamics of plant communities and soil development across multiple time-scales. However, they are often used inappropriately, leading to false conclusions about ecological patterns and processes, which has prompted recent strong criticism of the approach. Here, we evaluate when chronosequences may or may not be appropriate for studying community and ecosystem development. 2.,Chronosequences are appropriate to study plant succession at decadal to millennial time-scales when there is evidence that sites of different ages are following the same trajectory. They can also be reliably used to study aspects of soil development that occur between temporally linked sites over time-scales of centuries to millennia, sometimes independently of their application to shorter-term plant and soil biological communities. 3.,Some characteristics of changing plant and soil biological communities (e.g. species richness, plant cover, vegetation structure, soil organic matter accumulation) are more likely to be related in a predictable and temporally linear manner than are other characteristics (e.g. species composition and abundance) and are therefore more reliably studied using a chronosequence approach. 4.,Chronosequences are most appropriate for studying communities that are following convergent successional trajectories and have low biodiversity, rapid species turnover and low frequency and severity of disturbance. Chronosequences are least suitable for studying successional trajectories that are divergent, species-rich, highly disturbed or arrested in time because then there are often major difficulties in determining temporal linkages between stages. 5.,Synthesis. We conclude that, when successional trajectories exceed the life span of investigators and the experimental and observational studies that they perform, temporal change can be successfully explored through the judicious use of chronosequences. [source] Fresh insights into long-term changes in flora, vegetation, land use and soil erosion in the karstic environment of the Burren, western IrelandJOURNAL OF ECOLOGY, Issue 5 2009Ingo Feeser Summary 1. ,The study focuses on species-rich, upland, heathy vegetation with arctic-alpine floristic affinities and Sesleria grasslands in the karstic Burren region, western Ireland. The investigations aimed at reconstructing the long-term development of these high conservation-value communities and the role of farming in their formation and long-term survival. 2. ,The methods used included pollen analysis and 14C-dating of short monoliths and investigation of grykes (fissures in karstic limestone) for evidence of soil erosion. Special attention was paid to fossil, coprophilous fungal spores as indicators of local grazing. The strong local character of the pollen records facilitated identification of inter-site differences as well as regional patterns. It is shown that open pine woodland characterized the Cappanawalla uplands between c. 1500 BC and 500 BC. It is proposed that such woodlands, with floristic affinities to Scandinavian open pine woodlands on calcareous soils, provided a suitable environment for the present-day, open heath vegetation with species such as Dryas octopetala, Arctostaphylos uva-ursi, Geranium sanguineum and Empetrum nigrum. 3. ,Burning of vegetation as a management tool was important in the uplands over most of the last two millennia. Firing seems to have ceased with the onset of more intensive grazing regimes in the 18th century. 4. ,Synthesis. Upland palaeoarchives, derived from shallow peaty deposits, show that the upland Burren supported mainly plagioclimax Corylus -dominated woody vegetation and grasslands from c. 1500 BC (beginning of present record), until possibly as late as the 17th century AD. In the uplands of the north-western Burren, open, species-rich pinewoods with hazel dominated. The northern-arctic elements in the present-day upland flora survived clearances, involving initially Pinus sylvestris (c. 500 BC) and subsequently Corylus avellana (c. AD 1600). Colluvial material retrieved from grykes supports the idea of considerable soil loss occurring as late as the first and early 2nd millennium AD. The investigations highlight the potential of upland palaeoarchives, consisting of short sequences, for elucidating vegetation and land-use dynamics in karstic environments such as the Burren. [source] 55 Ice age kelp forests: climate-driven changes in kelp forest distribution since the last glacial maximumJOURNAL OF PHYCOLOGY, Issue 2003M. H. Graham Kelp forest distributions are constrained by the availability of rocky substrate within the depth range tolerable for growth and reproduction, which can vary over relatively short geological timescales (millennia) due to interactions between coastal bathymetry and climate-driven changes in eustatic sea level. Using GIS, a digital bathymetric map, sea level curves, and published kelp depth tolerances, I reconstructed changes in the size and distribution of giant kelp (Macrocystis pyrifera) forests in the Southern California Bight since the last glacial maximum. Reconstructions predicted that the total area of available kelp forest habitat for the California Channel Islands during the last glacial maximum (18.5 kyr BP; 628 square km) was greater than at present (382 square km) but less than at 16.5 kyr BP (1130 square km). Available kelp forest habitat along the southern California mainland also increased rapidly from 18.5 to 16.5 kyr BP but continued to increase with sea level rise. Differences in the effects of sea level rise on coastal geomorphology between the islands and mainland further constrained the extent of rocky substrate available to kelps. Given biomass and productivity estimates from present-day kelp forests, these reconstructions suggest more productive and spatially extensive island kelp forests near the last glacial maximum than at present, but the opposite pattern for the mainland. These climate-driven changes in kelp forest distribution and productivity likely had important historical impacts on the ecology and evolution of the present-day kelp ecosystem including kelp forest exploitation by early human inhabitants of southern California. [source] USING INCIDENT LIGHT TO MAXIMIZE RESOLUTION OF STRUCTURE ON DIATOM VALVES WITH A LIGHT MICROSCOPEJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Siver, P. A. Botany Department, Connecticut College, New London, CT 06320 Because of their abundance in a diverse array of aquatic habitats and chemical conditions, and the fact that their species-specific siliceous outer coverings remain for millennia in sediments, diatoms have become one of the most powerful organismal groups used in the reconstruction of historical environmental conditions. Although SEM is now needed to identify some species, the bulk of the identifications and data collection is still accomplished with a light microscope. In this paper I will demonstrate the use of interference reflection contrast (incident light) for the examination of diatoms that significantly improves the resolution of structural detail. Using incident light one can routinely distinguish between structures close to the theoretical limit of resolution for visible light, and about 70 nm closer together than resolvable with standard transmitted light optics. Examples of how the incident light technique can improve data collection with light microscopy will be given. Most research light microscopes could be easily and inexpensively outfitted to use this technique. [source] Fluvial response to Holocene climate change in low-order streams of central Mexico,JOURNAL OF QUATERNARY SCIENCE, Issue 5 2010Aleksander Borejsza Abstract Alluvial sequences constitute a recognised source of information on past environmental change, but one that has scarcely been tapped in central Mexico. This paper reviews what is currently known about the Holocene alluvial stratigraphy of the region, focusing on the interplay between climate and the pace and style of sedimentation in the incised headwater reaches of stream networks. The records obtained in five different drainage basins , four in the state of Tlaxcala and one in Guanajuato , are presented and compared to published reconstructions of climate change. A near-synchronous incision of all stream networks occurred close to 10 200 14C a BP in response to an increase in precipitation and stream discharge. A spell of very humid but markedly seasonal conditions ensued, resulting in the formation of wet meadows along streams and the accumulation of thick fine-textured valley fills dominated by cumulic soil A horizons. After 9100 14C a BP a transition to a warmer and more arid climate provoked the thinning of vegetation cover on slopes, accelerated runoff and increased sediment delivery to streams. The aggradation of coarser-textured valley fills poor in organic matter set in. It ceased or slowed down significantly after a few millennia as the studied stream reaches achieved a near-graded condition adjusted to the relatively stable climate. Arid mid Holocene conditions are also reflected in the abundant precipitation of secondary carbonates in Guanajuato. At 3100 14C a BP higher precipitation caused more frequent flooding and a resumption of aggradation. Shortly after that date sedentary farmers colonised Tlaxcala. Agriculture altered runoff and sediment delivery to streams and accelerated cut-and-fill cycles on a scale that masked the impact of any climatic fluctuations. Guanajuato was colonised later and its alluvial record suggests the persistence of a humid climate at least until 1000 14C a BP. Copyright © 2009 John Wiley & Sons, Ltd. [source] Ages and inferred causes of Late Pleistocene glaciations on Mauna Kea, Hawai'i,JOURNAL OF QUATERNARY SCIENCE, Issue 6-7 2008Jeffrey S. Pigati Abstract Glacial landforms on Mauna Kea, Hawai'i, show that the summit area of the volcano was covered intermittently by ice caps during the Late Pleistocene. Cosmogenic 36Cl dating of terminal moraines and other glacial landforms indicates that the last two ice caps, called Older Makanaka and Younger Makanaka, retreated from their maximum positions approximately 23,ka and 13,ka, respectively. The margins and equilibrium line altitudes of these ice caps on the remote, tropical Pacific island were nearly identical, which would seem to imply the same mechanism for ice growth. But modelling of glacier mass balance, combined with palaeotemperature proxy data from the subtropical North Pacific, suggests that the causes of the two glacial expansions may have been different. Older Makanaka air atop Mauna Kea was likely wetter than today and cold, whereas Younger Makanaka times were slightly warmer but significantly wetter than the previous glaciation. The modelled increase in precipitation rates atop Mauna Kea during the Late Pleistocene is consistent with that near sea level inferred from pollen data, which suggests that the additional precipitation was due to more frequent and/or intense tropical storms associated with eastward-moving cold fronts. These conditions were similar to modern La Niña (weak ENSO) conditions, but persisted for millennia rather than years. Increased precipitation rates and the resulting steeper temperature lapse rates created glacial conditions atop Mauna Kea in the absence of sufficient cooling at sea level, suggesting that if similar correlations existed elsewhere in the tropics, the precipitation-dependent lapse rates could reconcile the apparent difference between glacial-time cooling of the tropics at low and high altitudes. Copyright © 2008 John Wiley & Sons, Ltd. [source] Holocene climate change in the eastern Mediterranean region: a comparison of stable isotope and pollen data from Lake Gölhisar, southwest Turkey,JOURNAL OF QUATERNARY SCIENCE, Issue 4 2007Warren J. Eastwood Abstract Stable isotope and pollen data from Gölhisar Gölü, a small intramontane lake located in southwest Turkey, provide complementary records of Holocene climate change. Modern oxygen and hydrogen isotope water data are used as a means of comparing present-day isotope composition of the lake water to the past oxygen isotope composition of the lake water as calculated from 18O/16O ratios in calcite precipitated in the summer months. Despite the lake system being chemically dilute, the modern isotope data clearly establish that the lake water is evaporated in relation to its spring input, suggesting that the palaeo data can be interpreted primarily in terms of changing precipitation/evaporation ratios. ,18O and ,13C values from authigenic calcite through the Holocene show predominantly negative values indicating climatic conditions wetter than today. Particularly notable are low (depleted) isotope values during the earliest Holocene (ca. 10,600,8800 cal. yr. BP), a period for which pollen data imply drier conditions than at present. This divergence between pollen-inferred and stable isotope palaeoclimate data is found in other east Mediterranean lake sediment records, and suggests that vegetation may have taken several millennia to reach climatic equilibrium at the start of the Holocene. Isotopic fluctuations during the early-to-mid Holocene (8800,5100 cal. yr. BP) suggest oscillations between aridity and humidity. Higher ,18O and ,13C values for the second half of the Holocene indicate generally drier conditions than during the period before ca.5100 cal. yr BP although there is some evidence for increased humidity coinciding with pollen evidence for increasing human impact and intensification of agriculture, notably during the so-called Bey,ehir Occupation Phase (Classical and early Byzantine periods). The modern trend towards aridity started about 1300 yr ago. Copyright © 2006 John Wiley & Sons, Ltd. [source] Millennia-long tree-ring records from Tasmania and New Zealand: a basis for modelling climate variability and forcing, past, present and future,JOURNAL OF QUATERNARY SCIENCE, Issue 7 2006Edward R. Cook Abstract Progress in the development of millennia-long tree-ring chronologies from Australia and New Zealand is reviewed from the perspective of modelling long-term climate variability there. Three tree species have proved successful in this regard: Huon pine (Lagarostrobos franklinii) from Tasmania, silver pine (L. colensoi) from the South Island of New Zealand, and kauri (Agathis australis) from the North Island of New Zealand. Each of these species is very long-lived and produces abundant quantities of well-preserved wood for extending their tree-ring chronologies back several millennia into the past. The growth patterns on these chronologies strongly correlate with both local and regional warm-season temperature changes over significant areas of the Southern Hemisphere (especially Huon and silver pine) and to ENSO variability emanating from the equatorial Pacific region (especially kauri). In addition, there is evidence for significant, band-limited, multi-decadal and centennial timescale variability in the warm-season temperature reconstruction based on Huon pine tree rings that may be related to slowly varying changes in ocean circulation dynamics in the southern Indian Ocean. This suggests the possibility of long-term climate predictability there. Copyright © 2006 John Wiley & Sons, Ltd. [source] A precisely-dated lake-level rise marked by diatomite formation in northeastern IrelandJOURNAL OF QUATERNARY SCIENCE, Issue 1 2004G. M. Plunkett Abstract The intercorrelation of palaeoclimate events from various studies is often hindered by a lack of precise chronological control. Tephra isochrons can overcome this problem by providing direct site linkages. This paper outlines a study of Holocene peat and diatomite deposits that accumulated within the floodplain of Lough Neagh, Northern Ireland. The Icelandic Hekla 4 tephra has been identified at the base of diatomite deposits at a number of sites and provides firm dating evidence for a widespread flooding event in the area at ca. 2300 BC. The evidence is consistent with other studies in Ireland and elsewhere for increased wetness at this time. The results demonstrate that the terrestrial deposits around Lough Neagh contain an important record of Holocene lake-level change. Dendrochronological evidence from the Lough Neagh area provides additional information about lake-level fluctuations over the past two millennia. Copyright © 2004 John Wiley & Sons, Ltd. [source] Raman identification of natural red to yellow pigments: ochre and iron-containing oresJOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2008Françoise Froment Abstract Red and yellow natural (roasted) pigments have been used for millennia. This paper reports on the Raman characterization of about 50 pigments of the Ôkhra ,Mathériauthèque' collection from different origins: violet, red, orange, apricot, yellow ochre, Umbrian and Siena earths from France (Puisaye, Ardennes, Vaucluse), Italy (Siena, Sardinia, Venice, etc.), Germany, Sweden, Cyprus and India (Madras). Comparison is made with ,Bengara' Japanese pigments. Goethite is the chromophore of yellow pigments, and haematite (sometimes with magnetite) that of red ochre and earths. Umbrian pigment (,Terre d'Ombre') contains additional manganese oxides. Color shades are related to the content of secondary phases: iron oxides (haematite, goethite, magnetite), quartz, gypsum and anhydrite, calcite, dolomite, alums (jarosites), and to the Fe/M substitution in the haematite structure. The set of secondary phases can be used to confirm a provenance signature (Supplementary Material available). Copyright © 2008 John Wiley & Sons, Ltd. [source] Time series modelling of two millennia of northern hemisphere temperatures: long memory or shifting trends?JOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES A (STATISTICS IN SOCIETY), Issue 1 2007Terence C. Mills Summary., The time series properties of the temperature reconstruction of Moberg and co-workers are analysed. It is found that the record appears to exhibit long memory characteristics that can be modelled by an autoregressive fractionally integrated moving average process that is both stationary and mean reverting, so that forecasts will eventually return to a constant underlying level. Recent research has suggested that long memory and shifts in level and trend may be confused with each other, and fitting models with slowly changing trends is found to remove the evidence of long memory. Discriminating between the two models is difficult, however, and the strikingly different forecasts that are implied by the two models point towards some intriguing research questions concerning the stochastic process driving this temperature reconstruction. [source] The past, present, and future Aral SeaLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 3 2010Philip Micklin Abstract The Aral Sea, a once vast brackish terminal lake in the heart of Central Asia, has been rapidly drying since the 1960s. It had separated into four separate waterbodies by September 2009. The maximum water level decline was more than 26 m, whereas the lake surface area decreased 88% and the water volume 92%. The lake salinity increased by more than 20-fold. Prior to the modern recession, the Aral Sea experienced a number of water level declines and subsequent recoveries over the last 10 millennia. The main causative factor until the 1960s was the periodic westward diversion of the Amu Dar'ya, the main influent river, towards the Caspian Sea by both natural and human forces. The post-1960 recession, however, was overwhelmingly the result of unsustainable irrigation development. The lake's modern recession has caused a broad range of severe negative ecological, economic and human welfare problems. To restore the Aral Sea to its 1960s' size and ecological condition would be very difficult, if not impossible, in the foreseeable future. The plight of the Aral Sea, however, is far from hopeless. Partial restoration of portions of the lake is still feasible. A project to raise the Small (northern) Sea was completed in Fall 2005, raising its water level by 2 m, and lowering its salinity to a level not much higher than the early 1960 levels. Its ecological recovery has been dramatic, and a new project to improve further the Small Aral was recently announced. Improving the Large (southern) lake would be much more difficult and expensive. A project to save the deep Western Basin partially is technically feasible, however, and should be given careful evaluation. It is important to repair and preserve what is left of the deltas of the two tributary rivers, Syr Dar'ya and Amu Dar'ya, as these two rivers are of great ecological and economic value, and act as biological refugia for endemic species of the Aral Sea. [source] Law and regulation of retained organs: the ethical issuesLEGAL STUDIES, Issue 4 2002John Harris Organ retention has been with us for millennia. Walk into virtually any cathedral and many a church in Europe and you will nd an array of retained organs or tissue, allegedly originally the property of assorted saints, or even of God, and almost certainly collected without proper informed consent and retained in less than secure conditions. In our own time the complexities of organ collection, retention and use have proliferated.1 The events at Alder Hey Children's Hospital and the debates about the ethics of biobanking all over the world have dramatically highlighted the complexity, the difsiculty and the moral importance of these issues.2 Some of these issues have to do with the question of who can give permission for or consent to such removal and retention. Other issues involve consideration of whose rights or interests are engaged when cadaver organs and tissue are removed and retained, just what in particular is the nature, extent and force of those rights or interests, and how they are to be balanced against other moral considerations. These questions are the subject of this paper. We will not, however, here be concerned with the issues of genetic privacy, the security of genetic information. [source] | ||||||||||||||||||||||||||||||||||