bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards geographies of cyberspace
Authors: Kitchin Robert M.
Published: November 2003

This article uses two cyberspatial technologies, namely, the Internet (the global network of connected computers), and its close cousins, intranets (closed, private corporate telematic networks), to illustrate the ways in which geographers have engaged, and could engage, with studies of cyberspace. Virtual reality technologies are not discussed explicitly as, in the main, they are still at an exploratory and experimental stage. The article has three central aims: first, to introduce cyberspace and its implications to a wider geographical audience; secondly, to provide a critical review of current empirical and theoretical work relating to cyberspatial technologies by geographers; and, thirdly, to introduce geographers to the current debates and empirical research of scholars from other disciplines and suggest how geographers can build upon and advance these studies. An agenda for future research is outlined and an approach in which to ground future studies is forwarded. It is argued that spatiality is central to understanding cyberspace.
On the margins: the invisibility of communications in geography
Authors: Hillis Ken
Published: November 2003

Though a few geographers have made communication the object of study, communication has been undertheorized by Anglo-American geographers. When considered, communi cation has often been conflated with transportation, or been subject to quantification at the expense of sustained analysis of its implications for people and places. The increasingly central sociospatial concerns raised by new digital information technologies, however, suggest the urgency for the discipline to re-evaluate a reluctance to engage with communication processes that, until lately, because of their relative invisibility, may have seemed naturalized or beyond the disciplinary purview. Ironically, new communication technologies, because of the visual repre sentations in which they trade, allow social and human geography to incorporate study of communication without abandoning an empirical focus on the visible.
The end of geography or the explosion of place? Conceptualizing space, place and information technology
Authors: Graham Stephen
Published: November 2003

This article critically explores how the relations between information technologies and space and place are being conceptualized in a broad swathe of recent writings and discourses on the geographies of ‘cyberspace’ and information technologies. After analysing the powerful role of spatial and territorial metaphors in anchoring current discourses about information technologies and society, the article goes on to identify three broad, dominating perspectives. These I label the perspective of ‘substitution and transcendence’ (dominated by technological Utopianists), the ‘co-evolution’ perspective (drawing from political economy and cultural studies) and the ‘recombination’ perspective (derived from recent work in actor-network theory). The discussion turns to each in turn, extracting the geographical dimensions and implications of each. The article concludes by considering the implications of the discussion for spatial treatments of societytechnology relations and for broader debates about the nature of space and place.
Disability studies in human geography
Authors: Park Deborah C. , Radford John P. , Vickers Michael H.
Published: November 2003

Studies of disability have been rare in human geography until a recent blossoming of interest. In this article we review the expanding literature on disability, charting the process by which such studies have become newly significant in the field. Our initial focus is on physical disability after which we move on to issues around mental health and intellectual disability. In the concluding section we evaluate the significance of recent work on disability within human geography as a whole and suggest possible links to the growing literature on rights, social justice and ethics.
Engendering the Latin American state
Authors: Cravey Altha J.
Published: November 2003

Drawing on feminist theories of the state, this article critiques and extends the current usage of state theory in Latin Americanist geography. I argue that a nuanced mapping of social dynamics requires understanding the state as capitalist and patriarchal. Beginning with issues that are typically framed at the global scale, the review works progressively toward local and microscale analysis. Attention is given to distinct areas of scholarship which are appropriate for dealing with states and with the politics that produce and maintain them. Several questions are addressed throughout the review. First and most importantly, how have Latin Americanist geographers conceptualized the state? Secondly, have these conceptualizations been adequate for understanding the geography of state formation and dynamics? Thirdly, what have been the limitations and consequences of these approaches? Finally, how have state/society relations been understood? These questions guide a critical reading of the discipline's literature on the region while suggesting that a feminist critical realist perspective on the state offers powerful insights into Latin American politics, society and social change.
Is there progress in human geography? The problem of progress in the light of recent work in the philosophy and sociology of science
Authors: Bassett Keith
Published: November 2003

In this article I discuss the meaning of progress in geography and the social sciences in general in the light of recent debates in the philosophy and sociology of science. I review the way in which notions of progress derived from different philosophies of science have been used in geography in the past, before focusing on the kinds of constructivist challenges posed in recent work by authors such as Barnes. I criticize these approaches from a realist-constructivist perspective and argue for a deeper engagement with social epistemology.
Dialectics and difference: against Harvey's dialectical ‘post-Marxism’
Authors: Jones Andrew
Published: November 2003

David Harvey's recent book, Justice, nature and the geography of difference (JNGD), engages with a central philosophical debate that continues to dominate human geography: the tension between the radical Marxist project of recent decades and the apparently disempowering relativism and ‘play of difference’ of postmodern thought. In this book, Harvey continues to argue for a revised ‘post-Marxist’ approach in human geography which remains based on Hegelian-Marxian principles of dialectical thought. This article develops a critique of that stance, drawing on the work of Jacques Derrida, Gilles Deleuze and Felix Guattari. I argue that dialectical thinking, as well as Harvey's version of ‘post-Marxism’, has been undermined by the wide-ranging ‘post-’ critique. I suggest that Harvey has failed to appreciate the full force of this critique and the implications it has for ‘post-Marxist’ ontology and epistemology. I argue that ‘post-Marxism’, along with much contemporary human geography, is constrained by an inflexible ontology which excessively prioritizes space in the theory produced, and which implements inflexible concepts. Instead, using the insights of several ‘post-’ writers, I contend there is a need to develop an ontology of ‘context’ leading to the production of ‘contextual theories’. Such theories utilize flexible concepts in a multilayered understanding of ontology and epistemology. I compare how an approach which produces a ‘contextual theory’ might lead to more politically empowering theory than ‘post-Marxism’ with reference to one of Harvey's case studies in JNGD.
Emission characters of particulate concentrations and dry deposition studies for incense burning at a Taiwanese temple
Authors: Fang Guor-Cheng , Chu Chia-Chium , Wu Yuh-Shen , Fu Peter Pi-Cheng
Published: November 2003

Suspended particulate concentrations were measured at the Tzu Yun Yen temple in the Taichung region of Taiwan. The temple performs traditional incense burning. A universal sampler and a micro-orifice uniform deposited impactor (MOUDI) sampler with a dry deposition plate were used to measure the particulate concentrations. The results show that the average PM2.5/PM10 ratio was 74% during the incense burning period at this temple. In addition, the average suspended particulate (PM10) element concentration of anthropogenic element Zn (495 ng/m3) was higher than the other anthropogenic elements (Pb, Mn, Ni, and Cd). Furthermore, the average mass size distribution was bimodal with major peaks occurring at 0.32-0.56 mm and 5.6-10 mm during the incense burning period. The dry deposition velocities of Cd used fine particulates (PM2.5) and suspended particulate (PM10) mode were 1.86 and 0.99 cm/s in this study, respectively.
Predictors of survival after acute paraquat poisoning
Authors: Lee Eun-Young , Hwang Kyu-Yoon , Yang Jong-Oh , Hong Sae-Yong
Published: November 2003

Acute paraquat poisoning is often fatal. Many studies have investigated successful treatment modalities, but no standard treatment yet exists. The purpose of this study was to determine the predictors of survival after acute paraquat poisoning in 602 patients. The paraquat exposure was assessed based on the amount of ingested paraquat and a semiquantitative measure of the urine level of paraquat. Initial clinical parameters including vital signs, hemoglobin, white-blood-cell count, pH, PaCO2, PaO2, blood urea nitrogen, creatinine, aspartate aminotransferase, alanine aminotransferase, total bilirubin, amylase, and glucose were obtained at the time of arrival at the emergency room. Outcomes after acute paraquat poisoning were categorized as survivors and nonsurvivors. Multiple logistic regression analysis was applied to assess the predictors of survival after acute paraquat poisoning.

Some patients (55.5%) survived after oral ingestion of paraquat, whereas all those exposed to paraquat percutaneous or inhalational route survived. The amount of paraquat (24.5% concentrate of 1,1′-dimethyl-4,4′-bipyridium dichloride) ingested was 45.69 / 74.1 mL (mean9 / SD). In addition to degree of paraquat exposure, survival after acute paraquat poisoning was associated with age, respiratory rate, pH, PaCO2, hemoglobin, white-blood-cell count, blood urea nitrogen, amylase, and the number of failed organs in multiple logistic regression analysis. In conclusion, young age, percutaneous or inhalational route, exposure to less paraquat, and lesser degrees of leukocytosis, acidosis, and renal, hepatic, and pancreatic failures on admission are good prognostic factors of survival after acute paraquat poisoning.
Determination of hemoglobin adducts formed in rats exposed orally with 3,3′-dichlorobenzidine by GC/MS-SIM
Authors: Lee Jin Heon , Shin Ho-Sang
Published: November 2003

3,3?-dichlorobenzidine (DCB) can be metabolically N-acetylated and/or N-oxidized, and can form hemoglobin adducts. Gas chromatography/mass spectrometry-selected ion monitoring detection mode (GC/MS-SIM) could be a good analytical method to detect them. 4-Aminobiphenyl and phenanthrene-d10 were used as internal standards, and standard metabolites of DCB were synthesized from DCB. Pyridine is a promoter and acetic acid is a controller in the acetylation of DCB during titrating with acetyl chloride. After washing with acetone, the purity of N-acetyl DCB and N, N?-diacetyl DCB were 98.72% and 98.82%, respectively.

The maximum detection limits (MDLs) by GC/MS-SIM were 0.5 mg/L in DNA adduct and 1.0 ng/g in hemoglobin for DCB and N-acetyl DCB. The base peaks of their fragmentation pattern were 252 m/z at the peak of DCB, 252 m/z and 294 m/z at the peak of N-acetyl DCB, and 252 m/z, 294 m/z, and 336 m/z at the peak of N, N?-diacetyl DCB. This analytical method was applied to determine hemoglobin adducts formed in young female Sprague -Dawley rats orally exposed with 20, 30, and 40 mg DCB/kg/day for three weeks. Two adducts were detectable by GC/MS-SIM after alkaline hydrolysis of hemoglobin samples and extraction. The structure of these adducts could be assigned to DCB and N-acetyl DCB by co-chromatography with the synthetic standards.

After the first week of treatment, the total amount of hemoglobin adducts determined was 837.5∼2501 ng/g hemoglobin. The adduct levels were increased up to 1203.3∼2605.4 ng/g after the second week, and slightly decreased after the third week. The ratio of DCB and N-acetyl DCB was nearly similar in all treatment groups at the third week, such as 4.28∼4.78. Three different treatments (20, 30, and 40 mg DCB/kg) of rats resulted in dose-proportional increases in the total and DCB amount of hemoglobin adducted formed for three weeks. The relative contribution of DCB and N-acetyl DCB to the total hemoglobin adduct level was strongly dose dependent. The results show that GC/MS-SIM is suitable for the biological monitoring of humans exposed to DCB or DCB-containing products
Ecotoxicology and sustainable use of the planet
Authors: Cairns John
Published: November 2003

The goal of sustainable use is indefinite use of the planet by humankind. This objective, in turn, requires that the planet’s ecological life support system, consisting of natural capital and ecosystem services, remains healthy for an indefinite period. Achieving sustainability will require a new view of the responsibilities of professionals, such as ecotoxicologists, to ensure a healthy ecological life support system. Because both human society and natural systems are complex and multivariate, a high degree of uncertainty will remain. Therefore, sound judgment will be needed in determining what, if any, precautionary measures should be taken until more robust information has been gathered.

The role of ecotoxicologists in the quest for sustainable use of the planet is quite varied: 1) shifting goals and endpoints from an absence of harm to persuasive evidence of health; 2) increasing both temporal and spatial scales of ecotoxicological studies; 3) achieving a critical mass of qualified personnel; 4) including demographic change in ecotoxicological analysis and judgment; 5) developing new ecological thresholds; 6) being prepared for environmental surprises; 7) focusing on design for a quality environment; 8) developing ecosystem services as endpoints in ecotoxicological studies, and 9) being prepared for climate change and other events that might destabilize the biosphere and require major adjustments in the process of ecotoxicological testing. Both sustainable use of the planet and the field of ecotoxicology are rapidly developing fields that are mostly evolving in isolation from each other. To be successful, they must co-evolve.
Pycnogenol® in cigarette filters scavenges free radicals and reduces mutagenicity and toxicity of tobacco smoke in vivo
Authors: Zhang Deliang , Tao Yi , Gao Juntao , Zhang Chunai , Wan Sujun , Chen Yuxia , Huang Xiazhen , Sun Xiayou , Duan Shaojin , Schönlau Frank , Rohdewald Peter , Zhao Baolu
Published: November 2003

Despite large-scale anti-smoking campaigns throughout the world, the number of smokers remains high and cigarette smoking continues to represent a life-threatening health risk. Until a smoke-free society is achieved, reduction of cigarette smoke toxins may reduce the health burden. Current cigarette filter techniques are limited to the reduction of volatile tar constituents by dilution and by condensation on the filter surface. Vast quantities of harmful constituents, such as polycyclic aromatic hydrocarbons, heterocyclic (aromatic) amines, free radicals and reactive oxygen species, are inefficiently retained in the filter.

We investigated whether neutralisation of free radicals in cigarette filters is feasible and accompanied by a reduction in smoke toxicity. Addition of the bioflavonoid pine bark extract Pycnogenolfi to cigarette filters depleted free radicals in a dose dependent manner. This was paralleled by a reduction of toxicity and mutagenicity in rodent test models. In this model system, the acute toxicity of cigarette smoke was markedly reduced by up to 70% in rodents with 0.4 mg Pycnogenolfi in filters. Chronic exposure to cigarette smoke for 75 days revealed that Pycnogenolfifilters significantly reduced mutagenicity by up to 48% and decreased pathological changes in lung tissue.
Physicochemical determinants of linear alkylbenzene sulfonate (LAS) disposition in skin exposed to aqueous cutting fluid mixtures
Authors: Baynes Ronald E , Brooks James D , Barlow Beth M , Riviere Jim E
Published: November 2003

Linear alkylbenzene sulfonate (LAS) is added to cutting fluid formulations to enhance the performance of metal machining operations, but this surfactant can cause contact dermatitis in workers involved in these operations. The purpose of this study was to determine how cutting fluid additives influence dermal disposition of 14C-LAS in mineral oil-or polyethylene glycol 200 (PEG)-based mixtures when topically applied to silastic membranes and porcine skin in an in vitroflow-through diffusion cell system. 14C-LAS mixtures were formulated with three commonly used cutting fluid additives; 0 or 2% triazine (TRI), 0 or 5% triethanolamine (TEA), and 0 or 5% sulfurized ricinoleic acid (SRA). LAS absorption was limited to less than a 0.5% dose and the additives in various combinations influenced the physicochemical characteristics of the dosing mixture. LAS was more likely to partition into the stratum corneum (SC) in mineral oil mixtures, and LAS absorption was significantly greater in the complete mixture. TRI enhanced LAS transport, and the presence of SRA decreased LAS critical micelle concentration (CMC) which reduced LAS monomers available for transport. TEA increased mixture viscosity, and this may have negated the apparent enhancing properties of TRI in several mixtures. In summary, physicochemical interactions in these mixtures influenced availability of LAS for absorption and distribution in skin, and could ultimately influence toxicological responses in skin.
Holocene development of a peatland (southern Québec): a spatio-temporal reconstruction based on pachymetry, sedimentology, microfossils and macrofossils
Authors: Muller Serge D. , Richard Pierre J.H. , Larouchel Alayn C.
Published: November 2003

This study examines the relationships between allogenic and autogenic processes during the Holocene development of a southern Quebec bog. Local vegetation, surface moisture and peat accumulation were independently reconstructed from palaeoecological data (microfossils, macrofossils, loss-on-ignition and radiocarbon dating) and sedimentological analyses conducted on seven profiles. The observed successional stages, from pond to marsh, rich fen, poor fen then bog, represents a typical hydrosere. The early wetland development provides an obvious illustration of the facilitation model: each community modified the hydrological conditions by means of peat accumulation which then favoured the onset of the succeeding stage. No direct link is evidenced between vegetation, moisture and peat accumulation, while all of them clearly reveal the initial influence of minerotrophic groundwater supply. Notably, the decrease in this allogenic influence is reflected by the increasing asynchrony of local vegetation change. The comparison of the seven profiles also shows several asynchronous moisture fluctuations at the peatland scale but none seems to be related to climate. In contrast, net peat accumulation shows similar trends in all marginal profiles and at the peatland scale. As a consequence of the initial minerotrophic supply, peat-accumulation rates were high during the early Holocene and low during the midand late Holocene. Our results, which show the major influence of groundwater and autogenic processes on peat accumulation, strongly contrast with the general climatic control recognized for European peatlands.
Bayesian tools for tephrochronology
Authors: Buck Caitlin E. , Higham Thomas F.G. , Lowe David J.
Published: November 2003

It is suggested that Bayesian statistical methods for radiocarbon data interpretation, already widely used in archaeology, also have potential to improve the dating of tephra layers and hence enhance their use for tephrochronology. By re-analysing data from a recently published paper in which the authors sought to identify the calendar date of the eruption of fourteenth-century AD Kaharoa Tephra, a key marker in New Zealand prehistory, it is shown that Bayesian methods can be used to draw together a coherent collection of radiocarbon data, undertake formal outlier detection, and include prior information. Regardless of the calibration curve adopted, the distribution of likely dates for the Kaharoa eruption is multimodal. By including prior information from wiggle-matched dendrochronology, the uncertainty on the estimate of the calendar date is reduced from a range of about 100 years to about 25 years (i.e., 648-623 cal. BP, with modes at 638 and 632 cal. BP). Using sensitivity analysis, however, it is shown that such estimates are affected by the quality and nature of the prior information available. As a result, we urge tephrochronologists to seek fastidiously both high-quality radiocarbon data and reliable stratigraphic sequences that might inform future geochronological model building.
Evidence of Lateglacial and Holocene climatic change and human impact in eastern Anatolia: high-resolution pollen, charcoal, isotopic and geochemical records from the laminated sediments of Lake Van, Turkey
Authors: Wick Lucia , Lemcke Genry , Sturm Michael
Published: November 2003

Annually laminated sediments from Lake Van, spanning about 13000 varve years, were sampled for stable-isotopic, geochemical, pollen and charcoal analyses in order to find evidence of past regional climatic changes and human impact in the semi-arid region of eastern Anatolia, Turkey. The Lateglacial period was cold and dry, with steppe vegetation and saline lake water. During the Younger Dryas the lake level dropped dramatically, and the vegetation tumed to a semi-desert. Geochemical and isotopic records indicate a strong increase in moisture at the onset of the Holocene, and Arteinisia-chenopod steppes were partly replaced by grass steppe and pistachio scrub. A delay of about 3000 years in the expansion of deciduous oak woodlands and high steppe-fire frequencies suggest dry spring and summer weather during the early Holocene. At 8200 yr BP, a shift in the regional climate regime facilitated the transport of more moisture into the interior areas of the Taurus mountains and caused a change in the seasonal distribution of precipitation. The steppe-forests dominated by Quercus advanced and reached their maximum extention at about 6200 yr BP. All the proxy data indicate optimum climatic conditions, low water salinity and high lake level between 6200 and 4000 yr BP. After 4000 yr BP, aridity increased again and the modern climatic situation was established. Human impact in the catchment of Lake Van started at 3800 yr BP and was intensified during the last 600 years.
The late-Holocene history of Gormire Lake (NE England) and its catchment: a multiproxy reconstruction of past human impact
Authors: Oldfield Frank , Wake Rebecca , Boyle John , Jones Richard , Nolan Steve , Gibbs Zoe , Appleby Peter , Fisher Elizabeth , Wolff George
Published: November 2003

Sedimentary evidence spanning the last 3500 years from cores taken from the centre of Gormire Lake, Cleveland, northeast England, points to two periods of deforestation and catchment erosion. The first, mainly late Iron Age/Romano-British phase, began c. 200 BC and ended c. AD 600. The second began c. AD 1200, the time of early Monastic activity, and continued into the nineteenth century. The chronology for the core rests on 137Cs, 210Pb and 14C measurements and on the history of lead accumulation in the sediments. The majority of the AMS 14C dates are shown to be too old to varying degrees, depending on the source of the organic matter in the sediments. The record of vegetation change is derived from pollen analysis. Evidence for changes in sediment composition and source and for catchment erosion comes from magnetic measurements, element analyses using XRF, and organic biogeochemical analyses. There is a high degree of coherence between all these lines of evidence. Interpretation of the magnetic record is complicated as a result of the formation of biogenic magnetite by magnetotactic bacteria, especially during periods of minimal erosion, by the presence of the authigenic magnetic sulphide greigite and by probable magnetite dissolution. Despite these modifications to the magnetic mineral assemblage in the sediments, magnetic indications of catchment erosion are clearly distinguishable, especially in the record of the antiferromagnetic minerals haematite and goethite. Partial estimates of catchment erosion rates are presented, based on the evidence from the sediments from the deepest part of the lake.
Changes in surface productivity and subsurface denitrification during the Holocene: a multiproxy study from the eastern Arabian Sea
Authors: Agnihotri Rajesh , Bhattacharya S. K. , Sarin M. M. , Somayajulu B. L.K.
Published: November 2003

Spatial and temporal variations in the intensity of subsurface denitrification in the water-column of the eastem Arabian Sea have been investigated using chemical and isotopic proxies. The data show a steady increase in the denitrification intensity from ∼10 ka to ∼2 ka BP, probably caused by changes in surface productivity fuelled by strengthening of upwelling (monsoonal intensity). In addition, changes in redox conditions and detrital material input are assessed using abundances of a suite of major and trace elements. The temporal variations in some of the monsoonal proxies are characterized by periodicities of ∼1400 and ∼700 years, similar to those reported in the South Asian (Chinese) monsoon and high-latitude climate (north Atlantic region).
Climate-pollen relationships AD 1901–1996 in two small mires near the forest limit in the northern and central Swiss Alps
Authors: van der Knaap W. O. , van Leeuwen J. F.N.
Published: November 2003

Climatic relationships were established in two 210Pb dated pollen sequences from small mires closely surrounded by forest just below actual forest limits (but about 300 m below potential climatic forest limits) in the northern Swiss Alps (suboceanic in climate; mainly with Picea) and the central Swiss Alps (subcontinental; mainly Pinus cembra and Larix) at annual or near-annual resolution from ad 1901 to 1996. Effects of vegetational succession were removed by splitting the time series into early and late periods and by linear detrending. Both pollen concentrations detrended by the depth-age model and modified percentages (in which counts of dominant pollen types are down-weighted) are correlated by simple linear regression with smoothed climatic parameters with one-and two-year timelags, including average monthly and April/September daylight air temperatures and with seasonal and annual precipitation sums. Results from detrended pollen concentrations suggest that peat accumulation is favoured in the northern-Alpine mire either by early snowmelt or by summer precipitation, but in the central-Alpine mire by increased precipitation and cooler summers, suggesting a position of the northern-Alpine mire near the upper altitudinal limit of peat formation, but of the central-Alpine mire near the lower limit. Results from modified pollen percentages indicate that pollen pro duction by plants growing near their upper altitudinal limit is limited by insufficient warmth in summer, and pollen production by plants growing near their lower altitudinal limit is limited by too-high temperatures. Only weakly significant pollen/climate relationships were found for Pinus cembra and Larix, probably because they experience little climatic stress growing 300 m below the potential climatic forest limit.
Palaeoclimatic and archaeological evidence for a 200-yr recurrence of floods and droughts linking California, Mesoamerica and South America over the past 2000 years
Authors: Schimmelmann Amdt , Lange Carina B. , Meggers Betty J.
Published: November 2003

Conspicuous grey, clay-rich flood deposits in the predominantly olive, varved sediment in the central Santa Barbara Basin, California, were dated via varve-counting to c. AD 212, 440, 603, 1029, 1418 and 1605. The ∼200-yr quasi-periodicity and the timing of individual floods match time periods of known supraregional climatic changes and the documented ∼200-yr periodicity in palaeoclimate records elsewhere. The floods of c. AD 440 and AD 1418 occurred during global reorganizations of atmospheric circulation. Cold spells seem to have accompanied the floods of c. AD 1029 and AD 1605. California floods and other palaeoclimate records suggest that expressions of regional climates are modulated by solar variability with a ∼200-yr periodicity. Our compilation of palaeoclimatic and Mesoamerican and South American archaeological records provides evidence that palaeoenvironmental and cultural changes were often coincident within their respective dating uncertainties and occurred in ∼200-yr steps. The matching pattern supports the hypothesis that manifestations of changing climates, such as drought or flooding, served as destabilizing cofactors in transitions of precolumbian cultures. Extrapolation of the ∼200-yr recurrence pattern of Santa Barbara flooding suggests that catastrophic flooding in southern California may be expected for the early part of this century.
Dendroclimatic reconstruction of maximum summer temperatures from upper treeline sites in Interior British Columbia, Canada
Authors: Wilson R. J. S. , Luckman B. H.
Published: November 2003

Two independent reconstructions of maximum May–August temperatures are developed from a new network of Engelmann spruce tree-ring chronologies at treeline sites across Interior British Columbia (IBC). The IBC reconstruction (ad 1600–1997) uses the longest three ring-width (RW) and two maximum latewood density (MXD) chronologies from the region. The shorter (regional) reconstruction (REG, 1845–1997) is based on an independent, more broadly based network of chronologies (12 RW and 5 MXD) and verifies the regional signal in the parsimoniously sampled IBC reconstruction. Both models explain 53% of the regional temperature variance (1912–1995) and correlate strongly (r = 0.92) over their common period. The IBC reconstruction indicates two prolonged cooler intervals, c. 1620–1710 and 1775–1880, separated by warmer conditions that approached late twentieth-century normals between c. 1710 and 1730. The mean anomaly over the 1600–1900 period is estimated at 0.38°C below the 1961–1990 mean with the seventeenth century (1601–1700) being marginally colder than the nineteenth century (–0.53: –0.49°C). Both reconstructions model the rise in temperatures from the 1880s to 1940s and indicate that maximum summer temperatures since 1930 have been warmer than at any period since 1600. The IBC record from 1600–1900 is very similar to the mean summer-temperature record reconstructed in the adjacent Canadian Rockies, providing mutual verification for the regional nature of the signal in both reconstructions. This is the first maximum summer-temperature reconstruction from North America. Significant changes are also noted in the relationships between summer mean, maximum and minimum temperatures in this region in the last few decades with a greater absolute rate of increase in mean and minimum temperatures. These changing relationships suggest it is prudent to model tree-ring response to a variety of temperature parameters rather than using mean-temperature values.
Multiproxy dendroclimatology: a pilot study in northern Finland
Authors: McCarroll Danny , Jalkanen Risto , Hicks Sheila , Tuovinen Mervi , Gagen Mary , Pawellek Frank , Eckstein Dieter , Schmitt Uwe , Autio Jyrki , Heikkinen Olavi
Published: November 2003

Ten potential proxy measures of past climate were recovered from Scots pine (Pinus sylvestris) at three sites on a latitudinal transect close to the pine limit in northern Finland (earlywood, latewood and annual ring width; earlywood, latewood and maximum density; stable carbon isotope ratio; height increment; needle production; pollen deposition). Cambium dynamics were also monitored. The aim was to determine how climate influences each potential proxy and to decide which proxies are potentially useful for reconstructing climate. Height increment, needle and pollen production are strongly influenced by the temperature of the previous July, which is when the bud forms, but needle and particularly flower development may also be influenced by spring frosts. Maximum and latewood densities provide proxies of net photosynthesis. δ13C is controlled mainly by summer sunshine, reflecting the influence of photon flux on photosynthetic rate, and moisture stress which reduces stomatal conductance. By combining proxies, the strength of climate correlations is increased and the range of extractable parameters extended. The multiproxy approach provides a powerful means of extracting climatic information from long tree-ring chronologies.
A high-resolution record of late-Holocene moisture variability from a Michigan raised bog, USA
Authors: Booth Robert K. , Jackson Stephen T.
Published: November 2003

We reconstructed the late-Holocene surface-moisture history and vegetation dynamics of a raised bog in Michigan using testate amoebae, peat humification, pollen, stomata and plant macrofossils. Our primary objective was to compare bog palaeohydrology with the water-level history of Lake Michigan, and to regional and local vegetation changes. Hydrologic histories inferred from testate amoebae and humification show similar trends, and correspond with records of past water-level variability in Lake Michigan. The bog clearly shows effective-moisture increases during the Algoma highstand (∼3200–2300 cal. BP) and a later unnamed highstand (∼1900–1300 cal. BP). Some higher-frequency fluctuations are also similar. The good correspondence indicates that bog hydrology and the water levels of Lake Michigan have been driven by changes in large-scale atmospheric circulation patterns for at least the past 3500 years. Climate during the Algoma highstand may have been spatiotemporally complex, with increasing moisture occurring several hundred years earlier in the northern portion of the western Great Lakes basin. Locally, the expansion and contraction of Picea populations on the bog surface was probably directly related to moisture conditions. The well-documented decline in Fagus populations in the central Great Lakes region after 1000 cal. BP is contemporaneous with a major shift towards drier conditions, suggesting that relative dryness caused the decline.
Tree-ring records from central Fennoscandia: the relationship between tree growth and climate along a west–east transect
Authors: Linderholm H. W. , Solberg B. Ø. , Lindholm M.
Published: November 2003

Nine Scots pine tree-ring-width chronologies were compared regarding growth variability and response to climate along a gradient of oceanicity–continentality at 62–64°N in central Fennoscandia. The study revealed higher growth variance and stronger response to climate in the oceanic area west of the Scandi navian Mountains, compared to the more continental areas further east. However, there was a gradual change in radial tree growth and response to climate along the gradient, where tree growth in a transition zone between oceanic and continental climate showed positive correlations with radial tree growth in both oceanic and conti nental areas. Pine growth responded positively to summer temperatures in the western areas, and positively to summer precipitation in the east. Generally, pine growth showed a weaker relationship with the North Atlantic Oscillation (NAO) than with temperature and precipitation. During the summer, pine responded to the NAO only in western Fennoscandia, while during the winter pine responded to the NAO in both western and eastern Fennoscandia. This suggests that, during winter, the NAO is an adequate measure for climatic variations important for pine radial growth along the whole studied gradient, while, in the summer, the NAO is an inadequate measure for climatic variations important for pine radial growth east of the Scandinavian Mountains. During the second half of the twentieth century, pine growth in western Fennoscandia displayed reduced sensitivity to climate, while the opposite was found in the east. Indications of growth stress were found in one site east of the Scandinavian Mountains, and, as increasing temperatures have been accompanied by increasing precipitation in Fennoscandia throughout the twentieth century, we suggest that a change in climate regime from subcontinental to suboceanic caused those trees to experience climatic stress. However, trees in either oceanic or more continental areas did not seem to respond negatively to recent climatic change.
Early-Holocene spruce, Picea abies (L.) Karst., in west central Sweden as revealed by pollen analysis
Authors: Segerström Ulf , von Stedingk Henrik
Published: November 2003

Lateglacial and early Holocene macrofossils of Norway spruce (Picea abies) found in the Swedish Scandes have challenged the prevailing theory, based on pollen analyses, that spruce arrived rather late ( c. 3500 yr cal. BP) to Sweden. The aim of this study was to investigate whether the early-Holocene spruce establishment could be effectively assessed by pollen analysis. Four pollen analyses were carried out on peat mires in a river valley in the southern Swedish Scandes, where spruce has been present since the lateglacial. One site was analysed for the occurrence of macrofossil wood remains. The pollen diagrams display the local vegetation history for the last c., 10 000 years, and reveal the first occurrence of spruce pollen c. 9000 yr cal. BP. Spruce apparently became established in the northern part of the valley around 9000 BP, and thereafter spread south wards. The results are discussed in terms of the background pollen signal for spruce, i.e., local versus regional pollen, the presence or absence of forest on the sites during the Holocene, and the selection of study sites in relation to the aim of the investigation. Pollen analysis, as applied in this study, is shown to be a relevant method for the study of tree immigration in the early Holocene, at both a local and a landscape level.
Causes of extinction of vertebrates during the Holocene of mainland Australia: arrival of the dingo, or human impact?
Authors: Johnson C. N. , Wroe S.
Published: November 2003

The arrival of the dingo in mainland Australia is believed to have caused the extinction of three native vertebrates: the thylacine, the Tasmanian devil and the Tasmanian native hen. The dingo is implicated in these extinctions because, while these three species disappeared during the late Holocene of mainland Aus tralia in the presence of the dingo, they persisted in Tasmania in its absence. Moreover, the dingo might plausibly have competed with the thylacine and devil, and preyed on the native hen. However, another variable is similarly correlated with these extinctions: there is evidence for an increase in the human population on the mainland that gathered pace about 4000 years ago and was associated with innovations in hunting technology and more intensive use of resources. These changes may have combined to put increased hunting pressure on large vertebrates, and to reduce population size of many species that were hunted by people on the mainland. We suggest that these changes, which were quite dramatic on mainland Australia but were muted or absent in Tasmania, could have led to the mainland extinctions of the thylacine, devil and hen.
Comparison of human exposures to selected chemicals with thresholds from NTP carcinogenicity studies in rodents
Authors: Waddell William J
Published: November 2003

The National Toxicology Program (NTP) Technical Reports online database was reviewed to find chemicals that were reported to show clear evidence of carcinogenicity in the NTP rodent studies and for which data on human exposure could be found. Six representative compounds were selected. Three volatile compounds: ethyl benzene, perchloroethylene, and methylene chloride; two drugs in current use: phenytoin and primidone; and one naturally occurring, widely used, flavor: allyl isothiocyanate, were selected. The carcinogenicity data from each of the NTP Technical Reports were plotted using the Rozman scale to determine the threshold for carcinogenicity from the rodent studies. The human exposures for each chemical were calculated and compared with that threshold. The thresholds for carcinogenicity of the three volatile compounds were several orders of magnitude above the levels present in ambient air in the USA. The Threshold Limit Value (TLV) of the American Conference of Governmental Industrial Hygienists (ACGIH) for these three compounds varied between several orders of magnitude below the carcinogenicity threshold to being at the threshold. The maximum recommended doses of both drugs were at the carcinogenicity threshold. The estimated mean daily human consumption of the natural flavor was less than 100 × below the carcinogenicity threshold. This method of comparison between human exposure and animal carcinogenicity studies is more objective and informative than those in current use.
Plant poisonings in children in the Czech Republic, 1996-2001
Authors: Vichova Petra , Jahodar Ludek
Published: November 2003

Ingestion of or exposure to potentially poisonous plants is a relatively common presenting complaint in hospital paediatric departments, especially amongst toddlers. We present a retrospective study conducted to review the hospital admissions following acute childhood poisoning with plants in the Czech Republic over a 6-year period from 1996 to 2001. Six university hospital paediatric departments and two local hospital paediatric departments were involved in the study. Information and complete data on the cases were collected on the basis of all hospital medical records and internal hospital database outcomes. A total of 174 plant exposures were analysed to tabulate the list of top species involved in plant poisonings. The aims were to provide classification according to agent frequency, clinical presentations, severity of symptoms expressed, affected age groups and gender of patients and to evaluate the treatment according to patient outcome. The most frequent ingestions were of thorn apple seeds (14.9%), followed by dumb cane exposures (11.5%) and common yew (9.8%). Thorn apple, dumb cane, golden chain and raw beans caused the most serious symptoms. There were no fatalities reported out of the reviewed medical records. Complete data on plant poisoning in children from all over the territory of the Czech Republic are not available; however, we believe that the frequency of causes and the rank of plant species commonly involved are properly reflected in our study.
Aqueous extract of walnut (Juglans regia L.) protects mice against cyclophosphamideinduced biochemical toxicity
Authors: Haque R , Bin-Hafeez B , Parvez S , Pandey S , Sayeed I , Ali M , Raisuddin S
Published: November 2003

Walnut (Juglans regia L.) is extensively used in traditional systems of medicine for treatment of various ailments. It is described as an anticancer, tonic, blood purifier and detoxifier agent. The present study was undertaken to investigate modulatory effects of walnut extract on the toxicity of an anticancer drug, cyclophosphamide (CP) with special reference to protection against disruption of drug metabolizing and antioxidant enzymes. Plant extract+CP group animals showed restoration in the level of cytochrome P450 (CYP) content and in the activities of glutathione S-transferase (GST), glutathione peroxidase (GP) and catalase (CAT) in both liver and kidneys. But plant extract restored the activity of super oxide dismutase (SOD) and the level of reduced glutathione (GSH) in the kidneys only when compared with CP-treated animals. Plant extract treatment alone caused significant reduction in the content of CYP in the kidneys mainly. The extract showed a significant increase in the level of GSH and in the activities of GP in both the tissues and CAT in liver only, whereas no significant change was observed in the activities of GST and SOD. CP treatment resulted in a significant (P<0.01) increase in the lipid peroxidation (LPO) in the liver and kidneys compared with controls, while the extract CP treated group showed a significant decrease in the LPO in liver and kidneys when compared with the CP-treated group. The study shows that the use of J. regia extract might be helpful in abrogation of CP toxicity during the chemotherapy.
The effect of chronic lead exposure on the course of schistosomiasis in hamsters and the protective effect of the antioxidant preparation ‘Antox’
Authors: El-Gohary Mona , Yassin Abd-Elaziz , Shalabya Maisa A
Published: November 2003

Eighty adult male hamsters were used in this study, 20 of them were divided equally into a noninfected, nontreated control group and chronic lead exposed groups, which were given lead acetate intraperitoneally, dissolved in distilled water, 2 mg/kg/day for seven weeks. Then, two experiments were carried out on the remaining animals. Each experiment included 30 animals and was divided equally into three groups. Experiment A was carried out on the following groups: Schistosoma mansoni infected group, S. mansoni infected and chronic lead exposed group and S. mansoni infected, chronic lead exposed and ‘Antox’ treated group. Experiment B was done following the same design except that infection was carried out using Schistosoma haematobium cercaria. Chronic lead exposure of Schistosoma infected groups showed significant reductions in worm burden, tissue egg load and ova excretion in stool, liver and intestine. Compared with the control group, there were insignificant increases in serum and hepatic glutathione and malondialdehyde levels and a significant increase in hepatic 8-oxodeoxy guanosine phosphate (8-Ox-Dg) levels in Schistosomainfected groups. However, there was a significant increase in hepatic and blood lead levels, oxidative stress parameters and in the hepatic 8-Ox-Dg level in Schistosoma infected and chronic lead exposed groups as compared with their corresponding Schistosoma only infected groups. This study revealed a significant reduction in oxidative stress parameters as well as in blood and hepatic lead levels and in hepatic 8-Ox-Dg levels after giving Antox to the Schistosoma infected and chronic lead exposed groups. However, Antox increased insignificantly all the parasitological parameters studied in the Schistosoma infected and chronic lead exposed groups.