bluuebunny/crossref_metadata_2025_split huggingface dataset:
Skin penetration by cercariae of the bird schistosomeAustrobilharzia terrigalensis:the stimulatory effect of cholesterol
Authors: Clegg J. A. 
Published: June 2019

An artificial skin of hardened gelatine was used to examine the factors affecting penetration of skin by cercariae of the bird schistosome,Austrobilharzia terrigalensis.The percentage of cercariae able to penetrate through a gelatine membrane was increased by a factor of 3–4 by coating the membrane with a thin layer of lipid collected from the surface of chicken skin.The free sterol fraction, isolated from chicken skin surface lipid by thin-layer chromatography, stimulated penetration to the same extent as whole skin lipid.Cholesterol was detected in the sterol fraction by mass spectrometry and pure cholesterol had the full stimulating effect on cercarial penetration.Skin lipid, from which free sterols had been removed, lost the stimulatory effect on cercariae, but full activity was recovered by adding cholesterol to the sterol-free lipid. Fractions of skin lipid containing free fatty acids or triglycerides, wax esters and sterol esters similarly failed to stimulate penetration.These results establish that penetration ofA. terrigalensiscercariae is greatly stimulated by the free sterols present in the surface lipid of chicken skin but cholesterol may not be the only active sterol. Cholestanol and the plant sterols campesterol and β-sitosterol were also detected in chicken skin surface lipid. These sterols were not tested for activity on cercariae because samples free from cholesterol could not be obtained.Some cercariae were able to penetrate plain gelatine membranes not coated with cholesterol but small amounts of free sterol were detected in the gelatine itself. This sterol could not be completely removed by prolonged solvent extraction and consequently it is not known whether any cercariae are able to penetrate in the complete absence of sterols.Temperature had a marked effect on penetration of cercariae; lowering the temperature from 40 to 25 °C reduced the number of successful penetrants by a factor of 4.I am grateful to Miss V. Bowen for excellent technical assistance and to Dr J. McLeod of the Research School of Chemistry, Australian National University, who performed and interpreted the mass spectrometry. This investigation was partly supported by a research grant from the World Health Organization.
The blood picture resulting from Nuttallia (= Babesia) rodhaini and Nuttallia (= Babesia) microti infections in rats and mice
Authors: Nowell Frank 
Published: June 2019

The parasitaemia and associated blood picture following infections of Nuttallia rodhaini in rats and mice, and N. microti in rats are described. After inoculation of the blood stages of these parasites, it is evident that only further blood stages occur in the host animal. Infections with both piroplasms follow a similar course, there being a prepatent period followed by a patent infection which reaches a peak and then disappears. The prepatent period is an artifact due to the rarity of the parasites in the peripheral blood. The patent infection of N. rodhaini in rats and mice rapidly reaches a peak of up to 90% R.B.C. infected. That of N. microti develops more slowly and rarely reaches 20%. Rats show age resistance to both piroplasmoses but none is shown by mice aged up to 1 year against N. rodhaini infection. Increase of the parasite inoculum dose decreases the prepatent period and also the time from infection to the peak. In rats there is a corresponding increase of the peak but in mice this remains constant. N. microti infections in rats are enhanced by splenectomy, the peak being higher but the time from infection to the peak not altering. The parasitaemia produced by both piroplasms results in a temporary anaemia and reticulocytosis. The anaemia is not prolonged which does not suggest autoimmune reactions. Both piroplasms preferentially invade reticulocytes as compared with mature erythrocytes although this is apparently reversed at the onset of reticulocytosis.An explanation of the mechanism of the parasitaemia of the piroplasms in rats and mice is suggested.This paper is a report of work carried out in part for a thesis submitted for the degree of Ph.D. in the University of London. The work was aided by an S.R.C. research studentship. I would like to thank Dr F. E. G. Cox for his supervision and also for performing the splenectomies.
L'œuvre de la Croix-Rouge en Pologne
Authors: Dománska I. 
Published: June 2019

L'année 1969 marque le cinquantième anniversaire de la fondation de la Croix-Rouge polonaise.Dans notre pays, l'assistance qu'apportent la population et les associations bénévoles aux soldats blessés est née d'une tradition très ancienne et très belle; elle remonte aux temps de l'insurrection de Kosciuszko, et elle s'est poursuivie lors des insurrections nationales de 1830 et 1863. Durant les 120 années, et plus, de servitude et de démembrements que connut la Pologne, elle s'est étendue à ceux qui étaient emprisonnés parce qu'ils luttaient pour la liberté et la justice sociale. L'une des organisations d'assistance bénévole et de premiers secours fut appelée Société de la Croix-Rouge (1862–1886).
The Influence of Tillage Practices on Yields and Weed Control in Safflower
Authors: Fenster C. R. , Robison L. R. 
Published: June 2019

An experiment to investigate tillage practices for producing safflower (Carthamus tinctorius L.) and controlling weeds was conducted from 1963 to 1965. Three tillage intensities designated excessive, moderate, and minimum, depending on the number and kind of tillage operations performed prior to planting, were used. Three different tillage tools used as the primary implement in preparing the seedbed were sweep machine, oneway, and moldboard plow.Excessive, moderate, and minimum tillage plots averaged 342, 374, and 413 lb/A of safflower and 72, 73, and 63 lb/A of weeds, respectively. The sweep machine plots produced the highest safflower yields and lowest weed yields at all intensities with the oneway and moldboard plow about the same. Yields produced from the best treatments in the experiment (minimum tillage with the sweep machine and seeding with the shoe drill) averaged approximately 300 lb/A more than commercial fields and weed control was effective.
A History of Weed Control in the United States and Canada
Authors: Timmons F. L. 
Published: June 2019

Available literature indicates that relatively few agricultural leaders and farmers became interested in weeds as a problem before 1200 A.D. or even 1500 A.D. For many centuries, weed control was mostly incidental to tillage for seedbed preparation and growing of crops and to growing and cutting or pasturing of thickly planted crops. Occasional references in literature previous to 1900 mentioned use of mechanical devices and a few inorganic herbicides specifically for weed control.State weed laws directed at control of plant diseases were enacted during 1721 to 1766, but weed and seed laws involving weeds directly were not enacted until 100 to 200 years later. Only a few extension-type publications on weeds were issued in the United States and Canada between 1860 and 1900. There was a rapid increase in such publications after 1900. Research with inorganic chemicals as herbicides was begun in the 1890's in Europe and in a few states and provinces, and was increased at a rapid pace until the early 1940's. New developments in mechanical and biological control of weeds increased steadily during the same period. However, weed control remained a relatively minor phase of agronomy, botany, horticulture, agricultural engineering, and plant physiology until the early 1950's.About 10 years after the discovery of (2,4-dichlorophenoxy)acetic acid (2,4-D) in 1942–1944, the much increased interest of scientists, federal and state governments, industrial companies, and the general public had begun to bear fruit. The word “weed” or “weeds” began to appear in the titles of college courses and extension specialists. Weed conferences had been organized in six regions of the United States and Canada and in 10 states.The first meeting of the Weed Science Society of America was held in 1956 and Weed Science was adopted as its official journal. The number of herbicides in general use in the United States and Canada increased from 15 in 1940 to 25 in 1950, and to 100 in 1969. The total support for weed research in 1962 in the United States was six times that in 1950. The number of full-time research and extension workers or their equivalents in part-time workers had increased 20-fold and 13-fold, respectively, over the number in 1940.The rate of advancement in the art and science of weed control has increased so rapidly that the progress in each of the recent brief periods 1941 to 1968, 1901 to 1940, and 1800 to 1900 is considered greater than that in all previous periods, beginning about 6000 B.C.
The Churches, the State and Modern War
Authors: J. F.  
Published: June 2019

At its meeting in Uppsala, Sweden this summer, the World Council of Churches endorsed a principle that invites prolonged national discussion. With only a few negative votes, the 720 delegates adopted a resolution that endorses selective conscientious objection. The pertinent section from the 4,000 word statement entitled “Towards Justice and Peace in International Affairs” reads as follows:“Protection of conscience demands that the churches should give spiritual care and support not only to those serving in armed forces but also to those who, especially in the light of the nature of modern warfare, object to participation in particular wars they feel bound in conscience to oppose, or who find themselves unable to bear arms or to enter the military service of their nations for reasons of conscience. Such support should include pressure to have the law changed where required.”
Préhistoire africaine
Authors: Galy G.-R. 
Published: June 2019

Cette plaquette est une suite de monographies sur les stations préhistoriques ou plus tardives de la région du rio Muni, dans la Guinée anciennement espagnole, à 2° de latitude N.Certains niveaux archéologiques correspondent à une occupation fang, mais, sur les sites côtiers, abonde une céramique qui fut distribuée, dans tout l'Ouest africain, par la Compagnie hollandaise des Indes occidentales. Les gisements de l'Ile de Corisco, en particulier, traduisent des occupations successives, portugaise, hollandaise, allemande, anglaise et espagnole.
Nutrient Release From Permafrost Thaw Enhances CH4 Emissions From Arctic Tundra Wetlands
Authors: Lara Mark J. , Lin David H. , Andresen Christian , Lougheed Vanessa L. , Tweedie Craig E. 
Published: June 2019

AbstractHigh‐latitude climate change has impacted vegetation productivity, composition, and distribution across tundra ecosystems. Over the past few decades in northern Alaska, emergent macrophytes have increased in cover and density, coincident with increased air and water temperature, active layer depth, and nutrient availability. Unraveling the covarying climate and environmental controls influencing long‐term change trajectories is paramount for advancing our predictive understanding of the causes and consequences of warming in permafrost ecosystems. Within a climate‐controlled carbon flux monitoring system, we evaluate the impact of elevated nutrient availability associated with degraded permafrost (high‐treatment) and maximum field observations (low‐treatment), on aquatic macrophyte growth and methane (CH4) emissions. Nine aquatic Arctophila fulva‐dominated tundra monoliths were extracted from tundra ponds near Utqiaġvik, Alaska, and placed in growth chambers that controlled ambient conditions (i.e., light, temperature, and water table), while measuring plant growth (periodically) and CH4 fluxes (continuously) for 12 weeks. Results indicate that high nutrient treatments similar to that released from permafrost thaw can increase macrophyte biomass and total CH4 emission by 54 and 64%, respectively. However, low treatments did not respond to fertilization. We estimate that permafrost thaw in tundra wetlands near Utqiaġvik have the potential to enhance regional CH4 efflux by 30%. This study demonstrates the sensitivity of arctic tundra wetland biogeochemistry to nutrient release from permafrost thaw and suggests the decadal‐scale expansion of A. fulva‐dominant aquatic plant communities, and increased CH4 emissions in the region were likely in response to thawing permafrost, potentially representing a novel case study of the permafrost carbon feedback to warming.
Seasonal and Interannual Variability of Areal Extent of the Gulf of Mexico Hypoxia from a Coupled Physical‐Biogeochemical Model: A New Implication for Management Practice
Authors: Feng Yang , DiMarco Steven F. , Balaguru Karthik , Xue Huijie 
Published: June 2019

AbstractThe extent of hypoxia on the Louisiana shelf has been measured during July since 1985. The measured area was assumed to represent the seasonal maximum each year and was related to the Mississippi‐Atchafalaya riverine May NO2+3 loading and May–June total nitrogen loading, for planning management strategies. In this study, we analyze 25 years of simulations from a coupled physical‐biogeochemical model. An empirical orthogonal function analysis of the hypoxia frequency reveals that the dominant pattern is east‐west, with the seasonal maximum occurring in June, July, or August. This indicates that the July hypoxic area may or may not always be the largest of the year. A simple linear regression model was constructed to examine the explained variance of hypoxia attributable to nutrients. Results reveal that the May NO2+3 (May–June total nitrogen) loading can explain 35% ± 7% (54% ± 7%) of the maximum cumulative hypoxic area in contrast to 22% ± 9% (48% ± 12%) of the July cumulative hypoxic area. Our results suggest that the current nitrogen loading reduction suggested by the Hypoxia Task Force 2013 is not sufficient to reduce the 5‐year moving average Gulf's hypoxic zone to less than 5,000 km2. A reduction of at least 66% (48%) of May NO2+3 (May–June total N) loading is needed when using July hypoxic area as the criterion, while a reduction of 77% (60%) of May NO2+3 (May–June total N) loading is needed when using maximum hypoxic area.
The Importance of CH4 Ebullition in Floodplain Fens
Authors: Stanley K. M. , Heppell C. M. , Belyea L. R. , Baird A. J. , Field R. H. 
Published: June 2019

AbstractUncertainty in estimates of CH4 emissions from peatlands arise, in part, due to difficulties in quantifying the importance of ebullition. This is a particular concern in temperate lowland floodplain fens in which total CH4 emissions to the atmosphere (often measured as the sum of diffusive and plant‐mediated fluxes) are known to be high, but few direct measurements of CH4 ebullition fluxes have been made. Our study quantified CH4 fluxes (diffusion, plant‐mediated, and ebullition) from two temperate floodplain fens under conservation management (Norfolk, UK) over 176 days using funnels and static chambers. CH4 ebullition was a major component (>38%) of total CH4 emissions over spring and summer. Seasonal variations in quantifiable CH4 ebullition fluxes were marked, covering six orders of magnitude (5 × 10−5 to 62 mg·CH4·m−2·hr−1). This seasonal variability in CH4 ebullition fluxes arose from changes in both bubble volume flux and bubble CH4 concentration, highlighting the importance of regular measurements of the latter for accurate assessment of CH4 ebullition using funnels. Soil temperature was the primary control on CH4 ebullition fluxes. Elevated water level was also associated with increased CH4 ebullition fluxes, with a distinct increase in CH4 ebullition flux when water level rose to within 10 cm of the peat surface. In contrast, CH4 ebullition flux decreased steadily with increasing plant cover (measured as vascular green area). Ebullition was both steady and episodic in nature, and drops in air pressure during the two‐day funnel deployments were associated with higher fluxes.
Linking In Situ Photochemical Reflectance Index Measurements With Mangrove Carbon Dynamics in a Subtropical Coastal Wetland
Authors: Zhu Xudong , Song Lulu , Weng Qihao , Huang Guanmin 
Published: June 2019

AbstractPhotochemical reflectance index (PRI) has been found to be closely related with vegetation photosynthetic phenology in many ecosystems including boreal evergreen, but its ability to track carbon dynamics in low‐latitude evergreen mangrove ecosystems has rarely been assessed. To fill up this gap, this paper explored potential mangrove PRI‐carbon links and their environmental controls across temporal scales (diurnal and seasonal), based on 1‐year continuous high‐resolution (half‐hourly) time series measurements of spectral signals, eddy covariance carbon fluxes, and multiple environmental factors at a subtropical mangrove wetland of southeastern China. The diurnal variation of half‐hourly mangrove PRI, a U‐shaped changing pattern, was consistent with previous PRI studies on boreal evergreen, while the seasonal variation of daily mangrove PRI did not experience a hump‐shaped changing pattern as in boreal evergreen. Diurnal and seasonal mangrove PRI variations were significantly correlated with meteorological (radiation and vapor pressure deficit) and carbon‐related parameters (gross primary productivity, net ecosystem exchange, and light use efficiency), and the strength of diurnal PRI‐carbon correlations varied with meteorological factors with stronger correlations at enhanced radiation and vapor pressure deficit. Our results further indicated that physiology‐related PRI performed better than conventional structure‐related normalized difference vegetation index in tracking mangrove photosynthetic parameters. To the best of our knowledge, this is the first study to explore the link between high‐frequency PRI and carbon dynamics across temporal scales in natural mangrove ecosystems. The PRI‐carbon linkage confirmed by this study will improve our understanding of temporal variations in photosynthetic carbon dynamics in mangrove ecosystems.
The Impact of Peatland Restoration on Local Climate: Restoration of a Cool Humid Island
Authors: Worrall Fred , Boothroyd Ian M. , Gardner Rosie L. , Howden Nicholas J. K. , Burt Tim P. , Smith Richard , Mitchell Lucy , Kohler Tim , Gregg Ruth 
Published: June 2019

AbstractLand use, land use change, and forestry (LULUCF) have been directly altering climate, and it has been proposed that such changes could mitigate anthropogenic climate warming brought about by increases in greenhouse gas emissions to the atmosphere. Changes due to LULUCF alter the Bowen ratio, surface roughness, and albedo and so directly change air temperatures. Previous studies have focused on changes in the area of forestry and have used space‐for‐time substitutions to assess the impact of LULUCF. This study considered 18 years of daytime land surface temperature over an area of actual land use change in comparison to its surrounding landscape and considered the restoration of a lowland peat bog: satellite land surface temperature data across 49, 1‐km2 grid squares with 20 on peatland and 29 on surrounding agricultural land on mineral soils from 2000 to 2017. The peatland squares were, until 2004, dug for horticultural peat and after 2004 were restored with revegetation of bare soil and restoration of natural water tables. Over the 18 years, the average annual daytime land surface temperature significantly decreased for six grid squares, five of which were on the restored peatland where land surface temperature decreased by 2 K. In 2000, before restoration, the peatland was 0.7 K warmer than the surrounding agricultural land on mineral soils but by 2016 was 0.5 K cooler. This study has shown that anthropogenic land use change could cool a landscape and that functioning peatlands could act as cool, humid islands within a landscape.
Evaluation of CMIP6 DECK Experiments With CNRM‐CM6‐1
Authors: Voldoire A. , Saint‐Martin D. , Sénési S. , Decharme B. , Alias A. , Chevallier M. , Colin J. , Guérémy J.‐F. , Michou M. , Moine M.‐P. , Nabat P. , Roehrig R. , Salas y Mélia D. , Séférian R. , Valcke S. , Beau I. , Belamari S. , Berthet S. , Cassou C. , Cattiaux J. , Deshayes J. , Douville H. , Ethé C. , Franchistéguy L. , Geoffroy O. , Lévy C. , Madec G. , Meurdesoif Y. , Msadek R. , Ribes A. , Sanchez‐Gomez E. , Terray L. , Waldman R. 
Published: June 2019

AbstractThis paper describes the main characteristics of CNRM‐CM6‐1, the fully coupled atmosphere‐ocean general circulation model of sixth generation jointly developed by Centre National de Recherches Météorologiques (CNRM) and Cerfacs for the sixth phase of the Coupled Model Intercomparison Project 6 (CMIP6). The paper provides a description of each component of CNRM‐CM6‐1, including the coupling method and the new online output software. We emphasize where model's components have been updated with respect to the former model version, CNRM‐CM5.1. In particular, we highlight major improvements in the representation of atmospheric and land processes. A particular attention has also been devoted to mass and energy conservation in the simulated climate system to limit long‐term drifts. The climate simulated by CNRM‐CM6‐1 is then evaluated using CMIP6 historical and Diagnostic, Evaluation and Characterization of Klima (DECK) experiments in comparison with CMIP5 CNRM‐CM5.1 equivalent experiments. Overall, the mean surface biases are of similar magnitude but with different spatial patterns. Deep ocean biases are generally reduced, whereas sea ice is too thin in the Arctic. Although the simulated climate variability remains roughly consistent with CNRM‐CM5.1, its sensitivity to rising CO2 has increased: the equilibrium climate sensitivity is 4.9 K, which is now close to the upper bound of the range estimated from CMIP5 models.
Mid‐Holocene, Coral‐Based Sea Surface Temperatures in the Western Tropical Atlantic
Authors: Rodriguez Luis G. , Cohen Anne L. , Ramirez Wilson , Oppo Delia W. , Pourmand Ali , Edwards R. Lawrence , Alpert Alice E. , Mollica Nathaniel 
Published: June 2019

AbstractThe Holocene is considered a period of relative climatic stability, but significant proxy data‐model discrepancies exist that preclude consensus regarding the postglacial global temperature trajectory. In particular, a mid‐Holocene Climatic Optimum, ~9,000 to ~5,000 years BP, is evident in Northern Hemisphere marine sediment records, but its absence from model simulations raises key questions about the ability of the models to accurately simulate climate and seasonal biases that may be present in the proxy records. Here we present new mid‐Holocene sea surface temperature (SST) data from the western tropical Atlantic, where twentieth‐century temperature variability and amplitude of warming track the twentieth‐century global ocean. Using a new coral thermometer Sr‐U, we first developed a temporal Sr‐U SST calibration from three modern Atlantic corals and validated the calibration against Sr‐U time series from a fourth modern coral. Two fossil corals from the Enriquillo Valley, Dominican Republic, were screened for diagenesis, U‐series dated to 5,199 ± 26 and 6,427 ± 81 years BP, respectively, and analyzed for Sr/Ca and U/Ca, generating two annually resolved Sr‐U SST records, 27 and 17 years long, respectively. Average SSTs from both corals were significantly cooler than in early instrumental (1870–1920) and late instrumental (1965–2016) periods at this site, by ~0.5 and ~0.75 °C, respectively, a result inconsistent with the extended mid‐Holocene warm period inferred from sediment records. A more complete sampling of Atlantic Holocene corals can resolve this issue with confidence and address questions related to multidecadal and longer‐term variability in Holocene Atlantic climate.