Cliftonite in meteorites: a proposed origin     

Brett R  Higgins GT 《Science (New York, N.Y.)》1967,156(3776):819-820

Cliftonite, a polycrystalline aggregate of graphite with cubic morphology, is known in ten meteorites. Some workers have considered it to be a pseudomorph after diamond, and have used the proposed diamond ancestry as evidence of a meteoritic parent body of at least lunar dimensions.We have synthesized cliftonite in Fe-Ni-C alloys in vacuumn, as a product of decomposition of cohenite [(Fe, Ni)(3)C]. We therefore suggest that a high pressure origin is unnecessary for meteorites which contain cliftonite, and that these meteorites were formed at low pressures. This concluision is in agreement with other recent evidence.  相似文献   

A SNP map of the rat genome generated from cDNA sequences   总被引：1，自引：0，他引：1  

Zimdahl H  Nyakatura G  Brandt P  Schulz H  Hummel O  Fartmann B  Brett D  Droege M  Monti J  Lee YA  Sun Y  Zhao S  Winter EE  Ponting CP  Chen Y  Kasprzyk A  Birney E  Ganten D  Hubner N 《Science (New York, N.Y.)》2004,303(5659):807

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Community proteomics of a natural microbial biofilm     

Ram RJ  Verberkmoes NC  Thelen MP  Tyson GW  Baker BJ  Blake RC  Shah M  Hettich RL  Banfield JF 《Science (New York, N.Y.)》2005,308(5730):1915-1920

Using genomic and mass spectrometry-based proteomic methods, we evaluated gene expression, identified key activities, and examined partitioning of metabolic functions in a natural acid mine drainage (AMD) microbial biofilm community. We detected 2033 proteins from the five most abundant species in the biofilm, including 48% of the predicted proteins from the dominant biofilm organism, Leptospirillum group II. Proteins involved in protein refolding and response to oxidative stress appeared to be highly expressed, which suggests that damage to biomolecules is a key challenge for survival. We validated and estimated the relative abundance and cellular localization of 357 unique and 215 conserved novel proteins and determined that one abundant novel protein is a cytochrome central to iron oxidation and AMD formation.  相似文献   

Consumer Versus Resource Control in Freshwater Pelagic Food Webs     

MT Brett  CR Goldman 《Science (New York, N.Y.)》1997,275(5298):384-386

Models predict that food-web structure is regulated by both consumers and resources, and the strength of this control is dependent on trophic position and food-web length. To test these hypotheses, a meta-analysis was conducted of 11 fish (consumer)-by-nutrient (resource) factorial plankton community experiments. As predicted, zooplankton biomass was under strong consumer control but was weakly stimulated by nutrient additions; phytoplankton biomass was under strong resource control with moderate control by fish. However, the phytoplankton and zooplankton responses to nutrient additions did not follow theoretical predictions based on the number of trophic levels in the food web.  相似文献   

Prevention of organ allograft rejection by a specific Janus kinase 3 inhibitor     

Changelian PS  Flanagan ME  Ball DJ  Kent CR  Magnuson KS  Martin WH  Rizzuti BJ  Sawyer PS  Perry BD  Brissette WH  McCurdy SP  Kudlacz EM  Conklyn MJ  Elliott EA  Koslov ER  Fisher MB  Strelevitz TJ  Yoon K  Whipple DA  Sun J  Munchhof MJ  Doty JL  Casavant JM  Blumenkopf TA  Hines M  Brown MF  Lillie BM  Subramanyam C  Shang-Poa C  Milici AJ  Beckius GE  Moyer JD  Su C  Woodworth TG  Gaweco AS  Beals CR  Littman BH  Fisher DA  Smith JF  Zagouras P  Magna HA  Saltarelli MJ  Johnson KS  Nelms LF  Des Etages SG  Hayes LS  Kawabata TT 《Science (New York, N.Y.)》2003,302(5646):875-878

Because of its requirement for signaling by multiple cytokines, Janus kinase 3 (JAK3) is an excellent target for clinical immunosuppression. We report the development of a specific, orally active inhibitor of JAK3, CP-690,550, that significantly prolonged survival in a murine model of heart transplantation and in cynomolgus monkeys receiving kidney transplants. CP-690,550 treatment was not associated with hypertension, hyperlipidemia, or lymphoproliferative disease. On the basis of these preclinical results, we believe JAK3 blockade by CP-690,550 has potential for therapeutically desirable immunosuppression in human organ transplantation and in other clinical settings.  相似文献   

A Parametric Transfer Function for Grain-Flow Within a Conventional Combine Harvester     

Whelan  Brett M.  McBratney  Alex. B. 《Precision Agriculture》2002,3(2):123-134

Grain yield monitoring is an integral tool in the Precision Agriculture management system. When used in conjunction with a satellite-based navigation system, it provides spatial information on output variability, output response to managed inputs and is used to identify limiting resources in the crop production process. Accurately matching measured yield quantities with spatial units within a field is therefore important. At present, a simple linear time shift is employed by all commercial monitoring systems to account for the delay between GPS recorded positions and subsequent yield measurements. This study examines the internal process of grain transport to the sensor by monitoring the flow of strategically coloured grain. The flow is shown to be significantly influenced by mixing induced by threshing and auger transport processes. In contrast to the common assumption that grain moves as a spatially related cohort through to the sensor, the results suggest that a diffusion process is more realistic. A parametric model for the diffusion process is provided which suggests that from each individual yield measurement a maximum 20% of the mass could be assigned to a single spatial unit of the size that is typically allocated. The results imply that for further analyses, the inconclusive spatial origin and artificially smoothed quantities of instantaneous yield measurements should be considered.  相似文献   

Retraction     

Davis ST  Benson BG  Bramson HN  Chapman DE  Dickerson SH  Dold KM  Eberwein DJ  Edelstein M  Frye SV  Gampe RT  Grifffen RJ  Harris PA  Hassell AM  Holmes WD  Hunter RN  Knick VB  Lackey K  Lovejoy B  Luzzio MJ  Murray D  Parker P  Rocque WJ  Shewchuk-Chapman L  Veal JM  Walker DH  Kuyper LF 《Science (New York, N.Y.)》2002,298(5602):2327

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Characterization of lettuce (Lactuca sativa L.) grown with biopesticides and deltamethrin     

Simone Palma Favaro  Yardlei Carlos AlbaAnderson Dias Vieira de Souza  Antonio Camilo Arguelho ViannaAntonia Railda Roel 《Scientia Horticulturae》2011

The purpose of this study was to evaluate the physico-chemical characteristics and the post-harvest loss of mass of curly lettuce (Lactuca sativa L.) cv. Verônica that was grown in a protective environment with applications of biopesticides. The curly lettuce was treated by spraying with neem oil, cassava flour wastewater (manipueira), biofertiliser or the control treatment of deltamethrin. We determined the weight, circumference, dry matter, ash, crude protein, total phenols and minerals profile for the heads of lettuce. After harvesting, the lettuce was packed into opened plastic bags and kept at 5 °C for 5 days to evaluate its weight loss. No differences were observed among the treatments for the physico-chemical parameters. The lettuce that was sprayed with manipueira or biofertiliser had the greatest weight loss during storage. The achievement of similar yields with cheaper products suggests a benefit of using organic bioinsecticides.  相似文献   

Fat extraction from acid- and base-hydrolyzed food samples using accelerated solvent extraction     

Ullah SM  Murphy B  Dorich B  Richter B  Srinivasan K 《Journal of agricultural and food chemistry》2011,59(6):2169-2174

This paper describes a new in-cell method for pursuing accelerated solvent extraction (ASE) prior to lipid analysis from food samples. It is difficult to pursue direct ASE with acid- or base-hydrolyzed samples due to the corrosive nature of the reagents and material limitations. In this study ion exchange based materials were used to remove acid or base reagents in-cell without compromising the recovery of lipids. The performance data are presented here for the new methods for lipid extraction for a variety of food samples and compared to the Mojonnier method. NIST Standard Reference Materials (SRM-1546 and SRM-1849) were used to validate the ASE methods. Excellent fat recoveries were obtained for the ASE methods. The new methods presented here enhance the utility of ASE and eliminate labor intensive protocols.  相似文献   

Systematic landscape restoration using integer programming   总被引：1，自引：0，他引：1  

Neville D. Crossman  Brett A. Bryan 《Biological conservation》2006,128(3):369-383

In some agricultural regions, reservation of remnant natural lands will not maintain the natural biodiversity and large-scale ecological restoration is required. Geographic planning for restoration is essential to obtain the maximum ecological benefit from the limited resources available for landscape restoration. In this paper, we present a proof-of-concept that implements principles of systematic conservation planning, such as adequacy, representativeness, efficiency and flexibility, within an integer programming framework to identify geographic priorities for landscape restoration in a small catchment in South Australia. Integer programming ensures maximally efficient solutions that meet conservation targets in the form of minimum proportions (30%) and minimum areas (15 ha) of each environment type. However, the optimum solution identifies a system of scattered sites with an inadequate and impractical landscape structure. We propose a system of impedance surfaces that prioritise the spatial location of restoration towards improving landscape structure. Different options for systematic landscape restoration are assessed and the costs of spatial prioritisation of areas is found to be either optimal or very near optimal regardless of the impedances used. Thus, the cost of spatial prioritisation of sites for restoration in the landscape is negligible. We suggest the proposed methodology fits within a broader plan for landscape restoration and natural resource management.  相似文献