Unexpected changes to the global methane budget over the past 2000 years     

Ferretti DF  Miller JB  White JW  Etheridge DM  Lassey KR  Lowe DC  Macfarling Meure CM  Dreier MF  Trudinger CM  van Ommen TD  Langenfelds RL 《Science (New York, N.Y.)》2005,309(5741):1714-1717

We report a 2000-year Antarctic ice-core record of stable carbon isotope measurements in atmospheric methane (delta13CH4). Large delta13CH4 variations indicate that the methane budget varied unexpectedly during the late preindustrial Holocene (circa 0 to 1700 A.D.). During the first thousand years (0 to 1000 A.D.), delta13CH4 was at least 2 per mil enriched compared to expected values, and during the following 700 years, an about 2 per mil depletion occurred. Our modeled methane source partitioning implies that biomass burning emissions were high from 0 to 1000 A.D. but reduced by almost approximately 40% over the next 700 years. We suggest that both human activities and natural climate change influenced preindustrial biomass burning emissions and that these emissions have been previously understated in late preindustrial Holocene methane budget research.  相似文献   

Eruption of the nevado del ruiz volcano, Colombia, on 13 november 1985: gas flux and fluid geochemistry     

Williams SN  Lowe DR  Stoiber RE  Gemmell JB  Connor CB  P NG  C AL 《Science (New York, N.Y.)》1986,233(4767):964-967

The 13 November 1985 eruption of Nevado del Ruiz volcano, in Colombia, released a small volume of pyroclastic material and a disproportionately large volume of volcanic gas. Before the eruption, summit fumarole gases became less water-rich, and the sulfur/chlorine ratio increased. Remote measurements of sulfur dioxide flux after the eruption indicated active degassing at levels associated with eruptive or inter-eruptive stages of other volcanoes. Thermal water analyses revealed increases in magnesium, calcium, and potassium and an increase in the magnesium/chlorine ratio, suggesting that these elements may have been leached from new magma. Ash leachate data showed sulfate and chloride concentrations and ratios that would be expected for the late stages ofa major Plinian eruption. Water from the lahar contained high concentrations of sulfate and had a sulfur/chlorine ratio of 4.67, suggesting that water ejected from the crater lake and turbulent mixing of pyroclasts and glacial ice triggered the lahar. Microprobe analyses of pumice from this eruption and the most recent previous event showed similar mixed andesites. The uniform composition of the pumices and the unusually high ratio of gas to magma suggest that, although a new batch of magma triggered this eruption, the pumice that erupted may actually be old. Large volumes of new magma and glacial ice make the volcano dangerous and should stimulate development of an integrated long-term monitoring program to include Tolima volcano, 25 kilometers to the south.  相似文献   

Durable resistance to the wheat rusts: integrating systems biology and traditional phenotype-based research methods to guide the deployment of resistance genes   总被引：1，自引：0，他引：1  

Iago Lowe  Dario Cantu  Jorge Dubcovsky 《Euphytica》2011,179(1):69-79

Genes which confer partial resistance to the rusts in wheat figure prominently in discussions of potential durable resistance strategies. The positional cloning of the first of these genes, Lr34/Yr18 and Yr36, has revealed different protein structures, suggesting that the category of partial resistance genes, as defined by phenotype, likely groups together suites of functionally heterogenous genes. With the number of mapped partial rust resistance genes increasing rapidly as a result of ongoing advances in marker and sequencing technologies, breeding programs needing to select and prioritize genes for deployment confront a fundamental question: which genes or gene combinations are more likely to provide durable protection against these evolving pathogens? We argue that a refined classification of partial rust resistance genes is required to start answering this question, one based not merely on disease phenotype but also on gene cloning, molecular functional characterization, and interactions with other host and pathogen proteins. Combined with accurate and detailed disease phenotyping and standard genetic studies, an integrated wheat-rust interactome promises to provide the basis for a functional classification of partial resistance genes and thus a conceptual framework for their rational deployment.  相似文献   

Acclimation of the Critical Thermal Maximum of the Reptile Urosaurus ornatus     

Lowe CH  Vance VJ 《Science (New York, N.Y.)》1955,122(3158):73-74

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Turbidity current activity in a british columbia fjord     

Prior DB  Bornhold BD  Wiseman WJ  Lowe DR 《Science (New York, N.Y.)》1987,237(4820):1330-1333

A year-long monitoring program within an elongated channel-fan system in Bute Inlet of British Columbia, Canada, detected active sand-transporting turbidity currents. Measurements of bottom velocities and sediment collected in traps, as well as damage to moorings and equipment, captured the signatures of frequent energetic events. Maximum calculated velocities achieved were 335 centimeters per second, with flow thicknesses of more than 30 meters. Coarse sand was transported at least 6 to 7.5 meters above the sea floor. Turbidity currents flowed a minimum distance of 25.9 kilometers, but possibly as far as 40 to 50 kilometers, over bottom slopes of generally less than 1 degrees.  相似文献   

A critical vote down under     

Lowe I 《Science (New York, N.Y.)》2007,317(5845):1649

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"Overshoot" scenarios and climate change     

Huntingford C  Lowe J 《Science (New York, N.Y.)》2007,316(5826):829

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Contamination byErwinia carotovora of seed potato stocks of stem cutting origin in the process of multiplication     

M. C. M. Perombelon  R. Lowe  Evelyn M. Ballantine 《Potato Research》1976,19(4):335-347

Summary Surveys were done in the winters of 1973–4 and 1974–5 of 75 and 78 Scottish potato stocks, respectively, derived from stem cuttings. The results showed that these VTSC stocks were contaminated byErwinia carotovora early in their bulking, most being contaminated, often extensively, by the fifth year of multiplication. Especially in the early years of multiplication, the proportion ofE. carotovora var.carotovora toE. carotovora var.atroseptica was greater than that previously found in commercial stocks not derived from stem cuttings. Contamination levels in VTSC stocks were lower in the north than in the south, and in 1974–5 than in 1973–4. These differences were tentatively explained in terms of higher soil moisture deficits in the north in both years and in all regions in 1974 at a time during the growing season when the bacteria spread from the rotting mother tuber to the daughter tubers.

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Zusammenfassung Im Winter 1973/74 und 1974/75 wurden in Schottland 75 bzw. 78 Kartoffelpartien untersucht. Diese Kartoffelpartien, die aus virusgetesteten Stengelstecklingen (VTSC) hervorgegangen sind, wurden gleichm?ssig zwischen dem 1. und 5. Vermehrungsjahr verteilt und stammten von 16 (1973/74) und 20 (1974/75) Vermehrern, die mehr als die H?lfte der VTSC-Vermehrer in Schottland repr?sentieren (Fig. 1). Die Ergebnisse zeigten, dass die Kontamination mitErwinia carotovora sehr bald w?hrend der Vermehrung der Partien auftrat, die meisten waren im 5. Jahr der Vermehrung erheblich verseucht (Tabelle 1 und 2). Die Bestimmung der Arten zeigte, dass das Verh?ltnis vonE. carotovora var.carotovora zuE. carotovora var.atroseptica (dem Erreger der Schwarzbeinigkeit) in den ersten Jahren der Vermehrung gr?sser war als in den letzten Jahren und sogar dann noch gr?sser war, als das welches in Handelspartien gefunden wurde, die nicht aus Stengelstecklingen hervorgegangen waren (Tabelle 4). Soweit andere Herkünfte untersucht wurden, sind Insekten der wahrscheinlichste Grund für die Verseuchung der frühen Vermehrungsstadien, die h?ufiger mit var.carotovora als mit var.atroseptica kontaminiert sind. Der Grad der Kontamination war in Partien aus n?rdlichen Anbaugebieten geringer als aus südlichen und im allgemeinen 1974/75 auch geringer als 1973/74 (Tabellen 2 und 3). Es wurde versucht diese Unterschiede mit dem Feuchtigkeitsdefizit des Bodens (Fig. 2) zu erkl?ren, das im Norden in beiden Jahren und 1974 in allen Anbaugebieten w?hrend der Wachstumsperiode, in der sich die Bakterien von der verfaulenden Mutterknolle auf die Tochterknollen ausbreiten, gr?sser war.

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Résumé Des contr?les limités ont été entrepris en Ecosse pendant les hivers 1973–4 et 1974–5: ils portaient respectivement sur 75 et 78 lots de pommes de terre. Ces lots de classe VTSC ont été répartis de fa?on égale de la première à la cinquième année de multiplication et ils provenaient de 16 (1973–74) et 20 (1974–75) fermiers représentant environ la moitié des producteurs de plants VTSC d'Ecosse (fig. 1). Les résultats ont montré que la contamination parErwinia carotovora se produisait t?t dans l'ensemble des lots, la plupart desquels étaient contaminés, souvent de manière considérable, la cinquième année de multiplication (tableaux 1 et 2). L'identification variétale a montré que la proportion d'E. carotovora var.carotovora par rapport àE. carotovora var.atroseptica (l'agent pathogène de la jambe noire) avait tendance à être plus grande les premières années de multiplication que les dernières et même plus élevée que ce qui avait été précédemment trouvé dans les lots de plants commerciaux non issus de boutures (tableau 4). Parmi plusieurs sources possibles examinées, les insectes, qui sont plus couramment contaminés par la var.carotovora que par var.atroseptica sont la cause la plus probable de l'introduction de bactéries les premières années de multiplication. Les taux de contamination sont plus faibles dans les lots provenant des régions nord par rapport à ceux des régions du sud et sont en général plus bas en 1974–5 qu'en 1973–4 (tableaux 2 et 3). Une tentative d'explication de ces différences met l'accent sur le déficit en humidité du sol (fig. 2) qui tend à ètre plus élevé dans le Nord ces deux années et dans toutes les régions en 1974 pendant la période de végétation quand les bactéries se propagent du tubercule-mère pourri aux tubercules fils.

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Estimation of premature forests in Georgia (USA) using U.S. Forest Service FIA data and Landsat imagery     

Hojung Kim  Chris J. Cieszewski  Roger C. Lowe 《林业研究》2017,28(6):1249-1260

We used geographic information system applications and statistical analyses to classify young, premature forest areas in southeastern Georgia using combined data from Landsat TM 5 satellite imagery and ground inventory data. We defined premature stands as forests with trees up to 15 years old. We estimated the premature forest areas using three methods: maximum likelihood classification (MLC), regression analysis, and k-nearest neighbor (kNN) modeling. Overall accuracy (OA) of classifying the premature forest using MLC was 82% and the Kappa coefficient of agreement was 0.63, which was the highest among the methods that we have tested. The kNN approach ranked second in accuracy with OA of 61% and a Kappa coefficient of agreement of 0.22. Regression analysis yielded an OA of 57% and a Kappa coefficient of 0.14. We conclude that Landsat imagery can be effectively used for estimating premature forest areas in combination with image processing classifiers such as MLC.  相似文献   

Some normal values of thyroid function in horses     

F A Kallfelz  J E Lowe 《Journal of the American Veterinary Medical Association》1970,156(12):1888-1891

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