bluuebunny/crossref_metadata_2025 huggingface dataset:
Reflection of Scandinavian Ice Sheet Fluctuations in Norwegian Sea Sediments during the Past 150,000 Years
Authors: Baumann Karl-Heinz , Lackschewitz Klas S. , Mangerud Jan , Spielhagen Robert F. , Wolf-welling Thomas C.W. , Henrich Rüdiger , Kassens Heidemarie
Published: October 2002

The record of glacier fluctuations in western Scandinavia, as reconstructed from continental data, has been correlated with records of ice-rafted detritus (IRD) from well-dated sediment cores from the Norwegian Sea covering the past 150,000 yr B.P. The input of IRD into the ocean is used as a proxy for ice sheet advances onto the shelf and, thus, for the calibration of a glaciation curve. The marine results generally support land-based reconstructions of glacier fluctuations and improve the time-control on glacial advances. The Saalian ice sheet decayed very rapidly approximately 125,000 yr B.P. In the Early Weichselian, a minor but significant IRD maximum indicates the presence of icebergs in isotope substage 5b (especially between 95,000 and 83,000 yr B.P.). Reduced amounts of calcareous nannofossils indicate that surface waters were influenced by meltwater discharges during isotope substages 5d and 5b. An extensive build-up of inland ice began again during isotope stage 4, but maximum glaciation was reached only in early stage 3 (58,000-53,000 yr B.P.). Marine sediments have minimum carbonate content, indicating strong dilution by lithogenic ice-rafted material. Generally, the IRD accumulation rate was considerably higher in stages 4-2 than in stage 5. A marked peak in IRD accumulation rates from 47,000 to 43,000 yr B.P. correlates well with a second Middle Weichselian ice sheet advance dated by the Laschamp/Olby paleomagnetic event. Minimum ice extent during the Ålesund interstade (38,500-32,500 yr B.P.) and several glacial oscillations during the Late Weichselian are also seen in the IRD record. Of several late Weichselian glacial oscillations on the shelf, at least four correspond to the North Atlantic Heinrich events. Ice sheet behavior was either coupled or linked by external forcing during these events, whereas internal ice sheet mechanisms may account for the noncoherent fluctuations.
Successive Oceanic and Solar Forcing Indicated by Younger Dryas and Early Holocene Climatic Oscillations in the Jura
Authors: Magny Michel
Published: October 2002

The recent extension of (1) the residual Δ14C curve back to 11,400 cal yr B.P. and (2) the lake-level reconstruction in the Jura back to ca. 13,500 cal yr B.P. offers the opportunity of testing by proxy data the relationships between climate, atmospheric14C, the sun, and the ocean recently suggested from the atmospheric14C record. The climatic significance of the Jura record is supported by correlations with climatic oscillations reconstructed in the Alps from glaciers and timberline movements. Correspondence between the14C and paleoclimatic record from the Jura suggests a working hypothesis: two intervals within the Holocene can be distinguished in the middle latitudes of western and central Europe. An early Holocene period shows abrupt climatic oscillations linked to ocean forcing. Major colder climate phases developed between ca. 9000 and 8800, and between ca. 8000 and 7000 cal yr B.C. that coincide with higher Δ14C values. After 6000 cal yr B.C., a second period is characterized by smoother multicentury climatic oscillations linked to solar forcing.
Late Quaternary Vegetation and Climate of the Wind River Range, Wyoming
Authors: Fall Patricia L. , Davis P. Thompson , Zielinski Gregory A.
Published: October 2002

Sediments from Rapid Lake document glacial and vegetation history in the Temple Lake valley of the Wind River Range, Wyoming over the past 11,000 to 12,000 yr. Radiocarbon age determinations on basal detrital organic matter from Rapid Lake (11,770 ± 710 yr B.P.) and Temple Lake (11,400 ± 630 yr B.P.) bracket the age of the Temple Lake moraine, suggesting that the moraine formed in the late Pleistocene. This terminal Pleistocene readvance may be represented at lower elevations by the expansion of forest into intermontane basins 12,000 to 10,000 yr B.P. Vegetation in the Wind River Range responded to changing environmental conditions at the end of the Pleistocene. Following deglaciation, alpine tundra in the Temple Lake valley was replaced by a Pinus albicaulis parkland by about 11,300 14C yr B.P. Picea and Abies, established by 10,600 14C yr B.P., grew with Pinus albicaulis in a mixed conifer forest at and up to 100 m above Rapid Lake for most of the Holocene. Middle Holocene summer temperatures were about 1.5°C warmer than today. By about 5400 14C yr B.P. Pinus albicaulis and Abies became less prominent at upper treeline because of decreased winter snowpack and higher maximum summer temperatures. The position of the modern treeline was established by 3000 14C yr B.P. when Picea retreated downslope in response to Neoglacial cooling.
Influence of Late-Holocene Climate on Northern Rocky Mountain Mammals
Authors: Hadly Elizabeth Anne
Published: October 2002

An exceptionally rich paleontological site containing thousands of mammalian fossils and well-dated with 18 radiocarbon samples provides evidence of late-Holocene ecological response to climatic change in northern Yellowstone National Park, Wyoming. The mammalian fauna, composed of 10,597 identified specimens, shows surprising affinity to the local habitat with little evidence of long-distance transport of faunal elements, thus revealing the faithfulness of a fossil site to the community from which it is derived. The mammals illustrate ecological sensitivity to a series of mesic to xeric climatic excursions in the sagebrush-grassland ecotone during the past 3200 yr. From 3200 cal yr B.P. to a maximum of 1100 cal yr B.P., the species composition of mammals indicates wetter conditions than today. Beginning about 1200 cal yr B.P., the fauna becomes more representative of xeric conditions with maxima in xeric-indicator taxa and minima in mesic-indicator taxa, concordant with the Medieval Warm Period (circa 1000 to 650 yr B.P.). Cooler, wetter conditions which prevailed for most of the Little Ice Age (700 to 100 yr B.P.) in general correspond to a return to a more mesic mammalian fauna. A warm period within the Little Ice Age is documented by a xeric fauna. These data show that mammalian ecological sensitivity to climatic change over this intermediate time scale holds promise for predictions about the impacts of future global warming.
Late Holocene Eolian Activity in the Mineralogically Mature Nebraska Sand Hills
Authors: Muhs Daniel R. , Stafford Thomas W. , Swinehart James B. , Cowherd Scott D. , Mahan Shannon A. , Bush Charles A. , Madole Richard F. , Maat Paula B.
Published: October 2002

The age of sand dunes in the Nebraska Sand Hills has been controversial, with some investigators suggesting a full-glacial age and others suggesting that they were last active in the late Holocene. New accelerator mass spectrometry radiocarbon ages of unaltered bison bones and organic-rich sediments suggest that eolian sand deposition occurred at least twice in the past 3000 14C yr B.P. in three widely separated localities and as many as three times in the past 800 14C yr at three other localities. These late Holocene episodes of eolian activity are probably the result of droughts more intense than the 1930s “Dust Bowl” period, based on independent Great Plains climate records from lake sediments and tree rings. However, new geochemical data indicate that the Nebraska Sand Hills are mineralogically mature. Eolian sands in Nebraska have lower K-feldspar (and K2O, Rb, and Ba) contents than most possible source sediments and lower K-feldspar contents than dunes of similar age in Colorado. The most likely explanation for mineralogical maturity is reduction of sand-sized K-feldspar to silt-sized particles via ballistic impacts due to strong winds over many cycles of eolian activity. Therefore, dunes of the Nebraska Sand Hills must have had a long history, probably extending over more than one glacial–interglacial cycle, and the potential for reactivation is high, with or without a future greenhouse warming.
Dendroclimatic Reconstruction of April–May Temperature Fluctuations in the Western Himalaya of India Since A.D. 1698
Authors: Yadav Ram R. , Park Won-Kyu , Bhattacharyya Amalava
Published: October 2002

Ring-width chronologies of Himalayan cedar (Cedrus deodara (D. Don.) G. Don.), Himalayan pine (Pinus wallichiana A. B. Jackson), and Himalayan spruce (Picea smithiana (Wall.) Boiss.) from the western Himalayan region, India, have been used to reconstruct mean April–May temperature back to A. D. 1698. The reconstruction correlates significantly with the average April–May instrumental temperature record (r= +0.62, 1876–1988) and is characterized by annual to multiyear fluctuations. The most striking feature of the present reconstruction is the absence of any warming trend in the 20th century. Relationships between the mean April–May temperature for the western Himalayan region, Indian summer monsoon rainfall, and Southern Oscillation Index indicate that the tree-ring chronologies, as surrogate temperature records, will provide valuable data for climate change studies with regional and global perspectives.
Magnetic Susceptibility and Mineral Zonations Controlled by Provenance in Loess along the Illinois and Central Mississippi River Valleys
Authors: Grimley David A. , Follmer Leon R. , McKay E.Donald
Published: October 2002

Magnetic susceptibility (MS) patterns have proven useful for regional stratigraphic correlations of zones within thick, oxidized Peoria and Roxana Silts along the Illinois and Central Mississippi River valleys for more than 350 km. Variations in MS of C horizon loess are controlled by silt-sized magnetite content and are interpreted to reflect changes in sediment provenance due to fluctuations of the Superior and Lake Michigan glacier lobes and the diversion of the Mississippi River to its present course. Grain size distributions and scanning electron microscopic observations indicate that stratigraphic changes in MS are not significantly influenced by eolian sorting or diagenetic dissolution, respectively. Three compositional zones (lower, middle, and upper) are delineated within Peoria Silt which usually can be traced in the field by MS, the occurrence of clay beds, interstadial soils, and/or subtle color changes. These zones can be correlated with, but are generally of more practical use than, previously studied dolomite zones (McKay, 1977) or clay mineral zones (Frye et al.,1968). However, mineralogical analyses can help to substantiate zone boundaries when in question. MS and compositional zones may indirectly record a climatic signal, primarily through the effect that global cooling has had on ice lobe fluctuations in the Upper Mississippi drainage basin.
A 200,000-Year Record of Change in Oxygen Isotope Composition of Sulfate in a Saline Sediment Core, Death Valley, California
Authors: Yang Wenbo , Krouse H. Roy , Spencer Ronald J. , Lowenstein Tim K. , Hutcheon Ian E. , Ku Teh-Lung , Li Jianren , Roberts Sheila M. , Brown Christopher B.
Published: October 2002

δ18O values of sulfate minerals from a 186-m core (past 200,000 years) in Death Valley varied from +9 to +23‰ (V-SMOW). Sulfates that accumulated in the past ephemeral saline lake, salt pans, and mud flats have relatively low δ18O values similar to those of present-day local inflows. Sulfates that accumulated during two perennial lake intervals, however, have higher δ18O values, reflecting changes in temperature, lake water levels, and/or sulfur redox reactions. Over the same time interval, the δ18O record for sulfate had excursions that bear similarities to those found for carbonate in the Death Valley core, marine carbonate (SPECMAP), and polar ice in the Summit ice core, Greenland. The δ18O record differed considerably from the records reported for carbonate at Owens Lake and Devils Hole, which probably relates to different water sources. Death Valley, Owens Lake, and Devils Hole are responding to the same climatic changes but manifesting them differently. In Death Valley sediments, the isotopic composition of sulfate may have potential as an indicator of paleoenvironmental changes.
Declining Trend in the13C/12C Ratio of Atmospheric Carbon Dioxide from Tree Rings of South AfricanWiddringtonia cedarbergensis
Authors: February Edmund C. , Stock William D.
Published: October 2002

Stable carbon isotope chronologies using tree ring wood cellulose have proved useful for developing hypotheses on climate and environment change. However, within both the Southern Hemisphere and Africa there has been very little tree-ring-based isotope research. Here we report the first high-resolution (annual)13C/12C chronology for both Africa and the Southern Hemisphere. The 77-yr stable carbon isotope chronology was developed from sixWiddringtonia cedarbergensistrees from a site in the Cedarberg Mountains, Western Cape Province, South Africa. The results indicate that13C/12C ratios are not different from 1900 to 1949. After 1949, however, values become significantly more negative to 1977. The isotopic record from the pooled trees at the Die Bos site does not correlate with rainfall. This correlation is not significant even when theWiddringtoniastable carbon isotope record is de-trended for the anthropogenic CO2contribution. TheWiddringtoniarecord does, however, correlate significantly with atmospheric13C/12C CO2values derived from ice core data, tree ring13C/12C chronologies from the Northern Hemisphere, and recent Southern Hemisphere records.
Inter‐industry differences and the impact of operating and financial leverages on equity risk
Authors: Darrat Ali F. , Mukherjee Tarun K.
Published: October 2002

Based on the traditional assumption that the degree of combined leverage is strictly a product of operating and financial leverages (DOL and DFL), Mandelker and Rhee (1984) develop an interesting beta decomposition model. Two testable implications of their model, which apply to all firms, are that: (1) changes in DOL and/or DFL should exert a positive impact upon beta; and (2) a negative relationship should hold between DOL and DFL. Huffman (1983), however, questions this multiplicity assumption and, by arguing that a firm's capacity decision is endogenous, posits that an interaction prevails between a firm's DOL and DFL. An implication of Huffman's model is that the relationship between DOL, DFL, and beta depends on a firm's capacity decision and, therefore, may vary across industries. By employing a vector‐autoregressive causality approach, this study finds some evidence in support of Huffman's position.
A simple method for isolating import‐competent Arabidopsis chloroplasts
Authors: Aronsson Henrik , Jarvis Paul
Published: October 2002

We present a simple, rapid and low‐cost method for isolating a high yield of Arabidopsis chloroplasts that can be used to study chloroplast protein import. Efficiency of chloroplast isolation was dependent upon the ratio between amount of plant tissue and the buffer volume, the size and speed of the homogenisation equipment, and the size of the homogenisation beaker. The import method proved useful when characterising different precursor proteins, developmental stages and import‐defective mutants. Time‐course experiments enabled the measurement of import rates in the linear range. Compared to protoplastation, this isolation method has significant time and cost savings (∼80% and ∼95%, respectively), and yields chloroplasts with a higher capacity to import proteins.
Induction of human inhibitor of apoptosis protein‐2 by shear stress in endothelial cells
Authors: Jin Xin , Mitsumata Masako , Yamane Tetsu , Yoshida Yoji
Published: October 2002

To disclose the anti‐atherosclerotic mechanisms of steady laminar shear stress, we analyzed the expression of human inhibitor of apoptosis protein‐2 (HIAP‐2), whose gene was selected from a cDNA library of sheared endothelial cells (ECs), on ECs. HIAP‐2 was dose‐independently and time‐dependently induced in ECs by shear stress, regulated at the transcriptional level. HIAP‐2 expression was also identified in vivo. Shear stress‐mediated inhibition of EC apoptosis was associated with the inhibition of caspase‐3 activity, suggesting that the shear stress prevents EC apoptosis via negative regulation of caspase‐3 by the increment of HIAP‐2.
Cold‐induced mitochondrial uncoupling and expression of chicken UCP and ANT mRNA in chicken skeletal muscle
Authors: Toyomizu Masaaki , Ueda Masatoshi , Sato Shinichi , Seki Yoshinori , Sato Kan , Akiba Yukio
Published: October 2002

Although bird species studied thus far have no distinct brown adipose tissue (BAT) or a related thermogenic tissue, there is now strong evidence that non‐shivering mechanisms in birds may play an important role during cold exposure. Recently, increased expression of the duckling homolog of the avian uncoupling protein (avUCP) was demonstrated in cold‐acclimated ducklings [Raimbault et al., Biochem. J. 353 (2001) 441–444]. Among the mitochondrial anion carriers, roles for the ATP/ADP antiporter (ANT) as well as UCP variants in thermogenesis are proposed. The present experiments were conducted (i) to examine the effects of cold acclimation on the fatty acid‐induced uncoupling of oxidative phosphorylation in skeletal muscle mitochondria and (ii) to clone the cDNA of UCP and ANT homologs from chicken skeletal muscle and study differences compared to controls in expression levels of their mRNAs in the skeletal muscle of cold‐acclimated chickens. The results obtained here show that suppression of palmitate‐induced uncoupling by carboxyatractylate was greater in the subsarcolemmal skeletal muscle mitochondria from cold‐acclimated chickens than that for control birds. An increase in mRNA levels of avANT and, to lesser degree, of avUCP in the skeletal muscle of cold‐acclimated chickens was also found. Taken together, the present studies on cold‐acclimated chickens suggest that the simultaneous increments in levels of avANT and avUCP mRNA expression may be involved in the regulation of thermogenesis in skeletal muscle.
Chinese Military-Related Think Tanks and Research Institutions
Authors: Gill Bates , Mulvenon James
Published: October 2002

The national security research community in Beijing is dominated by think tanks and other research institutes affiliated with specific governmental institutions. The People's Liberation Army (PLA) maintains its own set of internal and affiliated research institutions, performing a variety of intelligence, exchange and research functions. The growth and professionalization of the Chinese military think tank community, combined with the widening degree of interaction between PLA researchers and foreigners presents a new set of challenges and opportunities for scholarly research. On the one hand, the new environment complicates the task of outside scholars as they seek to understand the biases and reliability of new sources of information. At the same time, it offers foreign scholars an unprecedented opportunity to test theories, delve into new research and improve understanding of the PLA. This article examines the roles, missions and composition of the units in this system, assesses the influence, authoritativeness and utility of the output from these organs, and offers some preliminary implications for Western study of the Chinese military.
The Politics of Introducing Direct Township Elections in China
Authors: Li Lianjiang
Published: October 2002

Based on archival sources and interviews, this article relates the untold story behind several township elections. It shows that these experiments were largely the result of a discursive opening on expanding grassroots democracy, and efforts by local leaders to promote their careers by taking the lead in initiating electoral reforms. It suggests that over two decades of post-Mao reform may have encouraged a belief among some local officials that history is on the reformers' side. It also suggests that the current cadre management system may enable mid-level leaders to introduce political reforms at a lower level without seeking prior approval from their superiors. The article argues that succession politics may re-open the door for further electoral reform and that the international community can offer protection to local initiatives by pressing the Chinese government to improve its human rights record.
Responses of tomato plants associated with the arbuscular mycorrhizal fungus Glomus clarum during drought and recovery
Authors: DELL'AMICO J. , TORRECILLAS A. , RODRÍGUEZ P. , MORTE A. , SÁNCHEZ-BLANCO M. J.
Published: October 2002

Mycorrhizal and non-mycorrhizal tomato plants (Lycopersicon esculentum Mill. cv ‘Amalia’) were subjected to water stress by withholding irrigation water for 72 hours and then reirrigated for 120 hours. Water stress reduced root mycorrhizal colonization, although the presence of the fungus Glomus clarum stimulated tomato plant growth. During the stress period the effect on the growth was more pronounced in aerial biomass than in the root biomass. The decrease in the soil water potential generated a decrease in leaf water potential (Ψl) and leaf turgor potential (Ψt), particularly in the non-mycorrhizal plants. Although the absence of osmotic adjustment provoked the loss of turgor in stressed plants, both Ψl and Ψt recovered after a short reirrigation period. Mycorrhizal infection improved photosynthetic activity (Pn) and stomatal conductance (gs) in non-stressed and stressed plants. These increases were accompanied by higher root hydraulic conductivity values, indicating enhanced water uptake in drought conditions. Neither Pn nor gs fully recovered after rewatering. The beneficial effect of the mycorrhizal symbiosis on the water status of tomato plants stimulated plant growth.
A model for predicting the age at sexual maturity for growing pullets of layer strains given a single change in photoperiod
Authors: LEWIS P. D. , MORRIS T. R. , PERRY G. C.
Published: October 2002

A model is presented which will predict mean age at first egg (AFE) for pullets of laying strains reared under non-limiting environmental conditions but exposed to a single change in photoperiod during the rearing stage. An initial analysis of 12 previously reported trials involving a wide range of genotypes showed that the response to an increase in photoperiod is not simply the inverse of the response to an equal decrease in photoperiod applied at the same age. Maximum sensitivity to a reduction in photoperiod was found shortly before onset of lay, whereas maximum sensitivity to an increment in photoperiod was observed at around 10 weeks of age. Two experiments were conducted to provide further data. The first compared the effect of 3-h increases in photoperiod from 8 h to 11 h or from 11 h to 14 h with the double increment from 8 h to 14 h and also tested a reduction from 11 h to 8 h, all imposed at 17 weeks of age. AFE was advanced to a similar extent by the changes from 8 to 11 h and from 11 to 14 h (9.8 and 10.9 days respectively). Response to the double increment was not additive: AFE on this treatment was 13.3 days earlier than for constant 8 h controls. Reduction in photoperiod from 11 to 8 h at 17 weeks delayed AFE by 18.7 days compared with constant 11-h controls. In the second experiment, pullets of two strains were transferred from 8 to 16-h photoperiods and from 16 to 8 h at 5, 7, 9, 15, 17 and 19 weeks of age. Controls were kept on constant 8 and constant 16-h days. Transfer from 8 to 16-h photoperiods at 5 weeks of age had no effect on AFE. At 7 weeks there was a bimodal response with some pullets subsequently showing advanced maturity and others not. Maximum stimulation of early maturity (31 days on average for the two genotypes) was obtained at 9 weeks of age and response to stimulation declined linearly with age thereafter. The delay in AFE resulting from a reduction in photoperiod (16 to 8 h) increased linearly between 0 and 15 weeks. At 17 and 19 weeks, the response was bimodal, with some pullets maturing at the same age as long-day controls and others showing delayed maturity. Using all this evidence and some other unpublished data, a model is developed to predict AFE as a function of mean photoperiod and change in photoperiod during the rearing phase. Elements are incorporated to allow for the insensitivity of pullets younger than 50 days to an increase in photoperiod and the effect observed late in rearing when a change in photoperiod comes too late to alter AFE for the most precocious individuals in a flock. Two coefficients are required to adjust for genotype. One describes mean AFE for the genotype when reared on constant daylength and the other defines the rate at which age effects the response to a single change in photoperiod.
Comparison of body water retention during water deprivation between swamp buffaloes and Friesian cattle
Authors: KOGA A. , KUHARA T. , KANAI Y.
Published: October 2002

The vasopressin (VP) and aldosterone responses of swamp buffaloes and Friesian cattle were compared during 3 days of ad libitum water availability and 3 days of water deprivation. During the period of hydration, buffaloes showed significantly higher VP concentrations (2.31±0.09 v. 1.23±0.07 pg/ml), in spite of larger water excretion rate through urine, relative to cattle. During the period of dehydration, although VP increased progressively in both species, the concentration in the buffaloes (66.7±18.6 pg/ml) was five times higher than that of the cattle (12.5±3.2 pg/ml) on Day 3. Even though the rate of urine excretion in the buffaloes decreased markedly during water deprivation, the total volume of urine excretion was still greater than that of the cattle. Haematocrit, serum osmotic pressure and total protein in both species increased significantly during water deprivation, but the rate of the increase was greater in buffaloes than in cattle. There was no correlation between sodium or potassium excretion and aldosterone concentration in either species. These results demonstrated that the VP elevation in buffaloes was largely attributable to the greater decrease of plasma volume caused by the greater water excretion. The lower retentivity of plasma volume probably means that buffaloes have a greater dependence on external water rather than to conserve internal water, because of the evolutionary adaptation of buffaloes to wet environments.
Caprine immunoglobulin G, β-lactoglobulin, α-lactalbumin and serum albumin in colostrum and milk during the early post partum period
Authors: LEVIEUX DIDIER , MORGAN FRANCOIS , GENEIX NATHALIE , MASLE ISABELLE , BOUVIER FREDERIC
Published: October 2002

Colostrum and milk samples from 20 goats were analysed for concentrations of immunoglobulin G (IgG), β-lactoglobulin (β-lg), α-lactalbumin (α-la) and serum albumin (CSA) throughout the first 14 milkings post partum (7 d of lactation) using single radial immunodiffusion assay. Concentrations (mg/ml, means±SD) at first milking were IgG 47·9±25·5, β-lg 30·7±10·4, α-la 2·77±0·82 and CSA 2·97±2·46 mg/ml. Large variations were recorded for IgG concentrations (19·9–94·5 mg/ml) and β-lg (9·3–49·8 mg/ml). Concentrations of IgG, β-lg and CSA dropped abruptly in the subsequent milkings and α-la concentration decreased slowly. Mean IgG concentration was <2 mg/ml after 7 milkings and <1 mg/ml after 11 milkings. However, IgG concentration does not differ significantly, at the 1% level, from milkings 7–14. The contribution of β-lg to the increase in whey proteins in early milks was greater than that of IgG from milkings 5 to 14. The results were tabulated to make it possible to calculate the excess of whey proteins that would be obtained if early milks were illegally added to milk supply.
Possible labile inhibition of the growth of Streptococcus uberis in milk from cows free from mastitis
Authors: KLIEM KIRSTY E. , HILLERTON J. ERIC
Published: October 2002

Milk from dairy cows never known to have had an intramammary infection with Streptococcus uberis can inhibit growth of Str. uberis for up to 7 h. This inhibition is abolished if milk is heated to 80 °C. Inhibition appears not to be related to immune defences as it occurs in skimmed milk (cell free), is unrelated to the concentration of immunoglobulin and survives heating to 56 °C. The effect is partly overcome by addition of selected amino acids and vitamins. It is suggested that the inhibition is caused by a restriction in the supply of essential nutrients part of which may require the conversion of plasminogen to plasmin.
On Linkhood, Topicalization and Clitic Left Dislocation
Authors: ALEXOPOULOU THEODORA , KOLLIAKOU DIMITRA
Published: October 2002

This paper focuses on the Information Packaging notion of linkhood and provides a structural definition of this notion for Greek. We show that a combination of structural resources – syntactic (left dislocation), morphological (clitic duplication) and phonological (absence of nuclear accent) – are simultaneously exploited to realize linkhood in Greek, a generalization that can be captured in a constraint-based grammar such as HPSG, which permits the expression of interface constraints. We assume Vallduví's (1992) approach to Information Packaging, and Engdahl & Vallduví's (1996) implementation of the latter in HPSG, but deviate from Vallduví's work in adopting Hendriks & Dekker's (1996) revised definition of linkhood that relies on non-monotone anaphora. From an empirical point of view, our approach directly accounts for the invariable association of Clitic Left Dislocated NPs with wide scope readings, as well as a number of systematic differences in felicity conditions between Clitic Left Dislocation and other apparently related phenomena (Topicalization and Clitic Doubling). From a theoretical perspective, our analysis departs from syntax-based notions of topichood or discourse-linking and supports a definition that unifies linkhood with other anaphora phenomena. As such, it arguably overcomes previously noted problems for Vallduví's treatment of links as the current-locus-of-update in a Heim-style file-card system.
Abnormal forms in the brittle-star Amphipholis squamata: a field study
Authors: Dupont Samuel , Mallefet Jérôme
Published: October 2002

Deviation from pentamerism is a rare phenomenon in 5-armed echinoderm species. Qualitative and quantitative data from field observations of 14 populations around the world were used for a biogeographical study of this phenomenon. Four abnormal forms presenting deviation from the classical pentamerism of echinoderms were observed within the brittle-star species Amphipholis squamata (Echinodermata: Ophiuroidea). Although these forms were rare in global populations (0·29%), they can reach important frequencies in some locations. Our results suggest that habitat structure has an influence on the occurence of abnormal forms. Moreover, deviations from pentamerism are not a heritable character but are a consequence of environmental perturbations on the metamorphosis of larvae and/or abnormal regeneration of arms.
Two distinct gait types in swimming frogs
Authors: Nauwelaerts Sandra , Aerts Peter
Published: October 2002

During terrestrial locomotion, frogs use two distinct gaits: out‐of‐phase leg movements associated with slow crawling behaviour and in‐phase leg movements during fast jumps. In Rana esculenta, crawling occurs during feeding, while jumping is used as an escape strategy. We examined whether a similar velocity‐dependent gait shift appears in swimming R. esculenta. Typically, swimming frogs propel themselves by kicking both hind limbs simultaneously. Observations of out‐of‐phase leg movements in swimming frogs have been reported, but were usually assumed to be associated only with directional changes. We demonstrate that alternating‐leg swimming is used quite frequently and that it results in a significantly lower velocity to the one obtained by using in‐phase leg movements. This difference is likely to be associated with energetic costs. Mathematical estimates of positive mechanical work required to move the centre of mass revealed that out‐of‐phase swimming is energetically less expensive than the in‐phase gait at a comparable speed, but may not be efficient at high speeds. Possible explanations for this phenomenon are higher inertial energy losses for in‐phase swimming, but at high speeds jet propulsion and an interaction effect may gain importance.
Clinical governance - a fascinating problem made dull by rhetoric
Authors: Vetter Norman J
Published: October 2002

Most of the things done by the professionals in the health service have evolved over the years through personal experience, expert views and trial and error. Since the last World War, initially with the randomized controlled trials of TB therapy, there has been increasing interest in objectively measuring the effect of treatment on patients. The proponents of this approach suggest that, where tested, personal experience, even in those with a great deal of experience, does not always allow us to draw our evidence from sufficient numbers nor does it immunize us against unfounded enthusiasm for one treatment over another.
Nutrition and longevity
Authors: Shibata Hiroshi , Kumagai Shu
Published: October 2002

Until recently, there has been relatively little scientific research investigating the influence of food or nutrient intake on longevity. This is partly due to the fact that most investigators have been interested in the relationship of food or nutrient intake to specific diseases i.e. communicable diseases, coronary heart disease and cancer of specific sites, rather than to overall mortality or longevity. Another significant factor is the difficulty of comparing the nutritional intake of populations, owing to the wide variability in individual intake and poor individual recall of specific food items in epidemiological studies.
Some mathematical models of frailty and their clinical implications
Authors: Rockwood Kenneth , Mitnitski Arnold B , MacKnight Chris
Published: October 2002

Frailty is a term that is used often, but commonly not defined precisely. As reviewed elsewhere most definitions share several features. Typically, older adults who are frail have a greater rate of dependence on others, so-called ‘loss of physiological reserve’ and multiple diseases. A dynamic component is often included (e.g. ‘loss of reserve’ and such synonyms as ‘unstable disability’ and ‘impaired homeostenosis’) and is manifest when, over time, patients respond less well to stress, or when those with given levels of frailty have higher rates of adverse outcomes. Still, the imprecision of the term frailty has led some to question its merit, and either to develop alternative means of classification or to stay with the concept of function and disability. Alternative methods of classification are either broadly or narrowly focussed.
Vibrational line broadening in the solid system N2-Kr: A molecular dynamics study
Authors: Lotz Heidi T. , Michels Jan P. J. , Schouten Jan A.
Published: October 2002

The vibrational band shapes and the related parameters of N2 in Kr have been calculated by molecular dynamics simulations as a function of the nitrogen concentration. Most of the simulations have been applied to the solid hcp phase at 5 GPa and 296 K. The calculated spectra have been obtained by full analysis of the relaxation function. Due to the limited size of the system, the particles remain near the same lattice point throughout a simulation run (no N2-Kr exchange). Upon dilution, the vibrational frequency of nitrogen in krypton shows a red shift. The full width at half maximum is extremely composition dependent, with a maximum value of 3.5 cm−1 at equal mole fractions. In addition, for the 50 and 75 mol % systems, a few special configurations with ordered distributions have been simulated. On the basis of these results together with earlier experimental data it is suggested that, in the real solid system, the nitrogen and krypton particles exchange places rapidly so that in time, each N2 molecule vibrates with all possible frequencies. To make an estimation of the exchange rate, several simulations have been performed during which the particles exchange randomly at various rates. The calculated widths depend strongly on the exchange rate. By comparison of the calculated and the experimental width of the spectra, an estimation of the exchange rate in the real system is made.
Wavelength-modulated fiber optic sensor for high precision displacement measurement
Authors: Berkovic G. , Rotter S. , Shafir E. , Scandale W. , Todesco E.
Published: October 2002

We describe an optical measurement system based on a fiber optic sensor that detects, with 20–30 μ accuracy, displacements of a remote reflective target at a distance of 200–500 mm. The light source is a single mode laser whose wavelength is ramped linearly in time. The requirements of laser ramp linearity and coherence in order to achieve the desired sensitivity are elaborated. The sensor can be operated with comparable accuracy in single-pass mode for a well aligned target, or in double-pass mode for a somewhat misaligned target. This sensor can be employed for remotely sensing minute displacements of objects in harsh environments, including the cryomagnets in particle accelerators.
Antiferromagnetic thickness dependence of blocking temperature in exchange coupled polycrystalline ferromagnet/antiferromagnet bilayers
Authors: Xi Haiwen , White Robert M. , Gao Zheng , Mao Sining
Published: October 2002

The exchange bias between an antiferromagnet (AF) and a ferromagnet (FM) vanishes at a temperature called the “blocking” temperature. Measurements are presented that show that the blocking temperature decreases with decreasing the thickness of the AF. This behavior is explained on the basis of a thermal fluctuation model, from which an analytic expression for the blocking temperature as a function of the antiferromagnetic thickness is obtained. This study also gives a quantitative understanding of the relationship between the blocking temperature and the AF grain size.
Intense pulsed helium droplet beams
Authors: Slipchenko Mikhail N. , Kuma Susumu , Momose Takamasa , Vilesov Andrey F.
Published: October 2002

Pulsed (30–100 μs) nozzle beams have been used to generate helium droplets (〈N〉=104–105). The dependence of the beam intensity and the mean droplet size on the source stagnation pressure and temperature are studied via mass spectroscopy and laser induced fluorescence of embedded phthalocyanine molecules. In comparison to a cw beam the pulsed source for the same pressure and temperature has a factor of 100 higher flux and the droplet sizes are 1 order of a magnitude larger.
Recombination-enhanced defect motion in forward-biased 4H–SiC p-n diodes
Authors: Skowronski M. , Liu J. Q. , Vetter W. M. , Dudley M. , Hallin C. , Lendenmann H.
Published: October 2002

The generation and evolution of defects in 4H–SiC p-n junctions due to carrier injection under forward bias have been investigated by synchrotron white beam x-ray topography, electroluminescence imaging, and KOH etching. The defects are Shockley stacking faults with rhombic or triangular shapes bound by partial dislocation loops with dislocation lines along Peierls valleys (〈11-20〉) or along the intersection of the basal plane containing the fault and diode surface. The Burgers vector of all bounding partials was of 1/3〈10-10〉-type. Among six possible types of partial dislocations with these properties, only two were observed in the volume of the epitaxial structure. One was tentatively identified as 30° carbon-core [C(g) 30°] and second as 30° silicon-core [Si(g) 30°] partial dislocation. Only one of them [proposed to be the Si(g) 30° partial] have been observed to move and emit light under forward bias. The other type of bounding dislocation [C(g) 30°] remained stationary during current injection. Low angle grain boundaries have been observed to act as one of a number of possible nucleation sites of stacking faults.
Effective optical properties associated with wave propagation in photonic crystals of finite length along the propagation direction
Authors: Jeong D.-Y. , Ye Y. H. , Zhang Q. M.
Published: October 2002

The effective properties associated with the propagation of electromagnetic waves in photonic crystals (PCs) are analyzed for one dimensional photonic crystals to illustrate the difference in those properties between infinitely extended and finite size photonic crystals (along the wave propagation direction). It is shown that the multiple reflections at the two end surfaces of a PC result in oscillations in transmittance, phase velocity, group velocity, as well as effective refractive indexes neff, which are often determined experimentally from the transmitted or reflected wave. At the frequencies far away from the bandgap, the oscillation in both the transmittance and neff can be modeled by treating the PC as an effective medium with the effective properties derived from the dispersion curves of the corresponding infinitely extended PC. As the frequencies approaching the band edges, however, the oscillations in both transmittance and neff are markedly enhanced due to the reflections from the internal interfaces in the PC. The results clearly demonstrate the importance of the two end faces on the effective properties of a finite size PC, which can be quite different from those deduced for an infinitely extended PC.
Effects of charge transfer on a-SiO2 surface structure: A molecular dynamics study
Authors: Wang Cheng , Kuzuu Nobu , Tamai Yoshimori
Published: October 2002

The effects of charge transfer between atoms on an amorphous SiO2 surface were studied by comparing a model with fixed charge (FQ) and a model that takes into consideration charge transfer by the charge equilibration (QEq) method. The QEq surface has more oxygen atoms and denser structures compared to the FQ sample. We found, on the surface of the QEq sample, three-coordinated Si with an O–Si–O bond angle in the range of 109–115°. This structure is similar to that of the experimentally observed E′ center (≡Si⋅). We also found a structure similar to the nonbridging oxygen hole center (≡Si–O⋅), which has been observed experimentally on a silica glass surface. These structures were not observed in the FQ model. The results suggest that consideration of the charge transfer is essential to reproduce the defect structure of the silica glass surface.
IrMn spin valves using Si layers
Authors: Carey M. J. , Le T. , Thompson T. , Gurney B. A.
Published: October 2002

Thin silicon layers can be used to good effect in spin valve sensors. Si underlayers increase the ΔR/R from 7.1% to 8.8% in top spin valves, and 6% to 7.8% for bottom spin valves. This is accompanied by a decrease in sheet resistance and the exchange anisotropy field. These results suggest that films grown on Si have larger grains than those with Ru seed layers. Si atoms are efficient as scattering sites, reducing ΔR/R and increasing the sheet resistance when placed in active layers. This can be used to improve the properties of antiparallel-pinned spin valves.
Two stages in the kinetics of gold cluster growth in ion-implanted silica during isothermal annealing in oxidizing atmosphere
Authors: De Marchi G. , Mattei G. , Mazzoldi P. , Sada C. , Miotello A.
Published: October 2002

The growth kinetics of gold clusters, formed by ion implantation in silica, is experimentally investigated. Isothermal sample annealing at 900 °C is performed in air atmosphere for increasing time intervals in the range between 0.5 and 12 h. Two different scaling laws of the cluster average radius with time, t1/2 and t1/3, are evidenced, proving that coarsening, i.e., Ostwald ripening, follows the stage of diffusion limited cluster growth, as the annealing time interval increases. By a comparative analysis of the two regimes of cluster growth, in the framework of linearized models for clustering processes, the value of the surface tension of gold nanoparticles in silica matrix has been evaluated.
Rotary resonance recoupling for half-integer quadrupolar nuclei in solid-state nuclear magnetic resonance spectroscopy
Authors: Wi Sungsool , Logan John W. , Sakellariou Dimitris , Walls Jamie D. , Pines Alexander
Published: October 2002

Investigations were made of rotary resonance recouplings (R3) of chemical shift anisotropy (CSA), heteronuclear dipolar (HTD), and homonuclear dipolar (HMD) couplings involving half-integer quadrupolar nuclei under magic-angle sample spinning condition. Under rotary resonance conditions provided by a low amplitude rf field and a high spinning speed, the spectrum of the central transition coherence of half-integer quadrupolar nuclei shows recouplings of CSA, HTD, and HMD interactions that depend on the ratio of the rf field to the spinning speed. These new properties can be used to extract electronic and structural information about the sample that are otherwise difficult to extract in the presence of a dominant quadrupolar interaction. An average Hamiltonian theory is used to explain the recoupling properties of various interactions. Experimental implementations of the R3 are demonstrated on model compounds with spin-3/2 systems.
Local correlation mechanisms in ionic compounds: Comparison with x-ray scattering experiments
Authors: Ragot Sébastien , Gillet Jean-Michel , Becker Pierre J.
Published: October 2002

Electron correlation effects are often invoked as possible causes of differences between experimental and Hartree–Fock Compton profiles. The shape as well as the magnitude of these differences can be very different, depending on materials. In order to illustrate this, we performed post Hartree–Fock calculations on small LiH and MgO ionic clusters. The subsequent correlation corrections significantly improve Compton profiles and structure factors versus their experimentally determined counterparts. The opposite trends observed at small momenta for experimental deviations to Hartree–Fock Compton profiles of LiH and MgO are then qualitatively explained through an empirical model for a confined two-electron anion. This model further suggests that the confinement of the embedded anion favors the angular correlation mechanism.
Bonding in the oxo ferrous iron species: A complete active-space self-consistent-field theory verification of the molecular-oxygen-like pattern
Authors: Zilberberg Igor , Gora Robert W. , Zhidomirov George M. , Leszczynski Jerzy
Published: October 2002

The bonding of atomic oxygen to ferrous iron was studied using the Fe(OH)2 system as a model of the ferrous iron center. All lowest triple, quintet, and septet states of OFe(OH)2 were studied at the complete active-space self-consistent-field theory level augmented by multireference second-order-perturbation theory. In addition the density functional theory with three-parameter exchange functional of Becke and correlation functional of Lee, Yang, and Parr has been applied to this system. The ground state has been found to have A51 symmetry. The electron configuration responsible for this state is similar to that of molecular oxygen: there are the doubly occupied σ and π shells and singly occupied π* orbitals. The only difference revealed in this study is the presence of nonbonding half-filled dδ orbitals.