11,142 research outputs found

    Organocatalytic Lewis base functionalisation of carboxylic acids, esters and anhydrides via C1-ammonium or azolium enolates

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    This tutorial review highlights the organocatalytic Lewis base functionalisation of carboxylic acids, esters and anhydrides via C1-ammonium/azolium enolates. The generation and synthetic utility of these powerful intermediates is highlighted through their application in various methodologies including aldol-lactonisations, Michael-lactonisations/lactamisations and [2,3]-rearrangements.Publisher PDFPeer reviewe

    The significance of SNODENT

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    SNODENT is a dental diagnostic vocabulary incompletely integrated in SNOMED-CT. Nevertheless, SNODENT could become the de facto standard for dental diagnostic coding. SNODENT's manageable size, the fact that it is administratively self-contained, and relates to a well-understood domain provides valuable opportunities to formulate and test, in controlled experiments, a series of hypothesis concerning diagnostic systems. Of particular interest are questions related to establishing appropriate quality assurance methods for its optimal level of detail in content, its ontological structure, its construction and maintenance. This paper builds on previous–software-based methodologies designed to assess the quality of SNOMED-CT. When applied to SNODENT several deficiencies were uncovered. 9.52% of SNODENT terms point to concepts in SNOMED-CT that have some problem. 18.53% of SNODENT terms point to SNOMED-CT concepts do not have, in SNOMED, the term used by SNODENT. Other findings include the absence of a clear specification of the exact relationship between a term and a termcode in SNODENT and the improper assignment of the same termcode to terms with significantly different meanings. An analysis of the way in which SNODENT is structurally integrated into SNOMED resulted in the generation of 1081 new termcodes reflecting entities not present in the SNOMED tables but required by SNOMED's own description logic based classification principles. Our results show that SNODENT requires considerable enhancements in content, quality of coding, quality of ontological structure and the manner in which it is integrated and aligned with SNOMED. We believe that methods for the analysis of the quality of diagnostic coding systems must be developed and employed if such systems are to be used effectively in both clinical practice and clinical research

    Atlas of wide-field-of-view outgoing longwave radiation derived from Nimbus 6 Earth radiation budget data set, July 1975 to June 1978

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    An atlas of monthly mean outgoing longwave radiation global contour maps and associated spherical harmonic coefficients is presented. The atlas contains 36 months of continuous data from July 1975 to June 1978. The data were derived from the first Earth radiation budget experiment, which was flown on the Nimbus-6 Sun-synchronous satellite in 1975. Only the wide-field-of-view longwave measurements are cataloged in this atlas. The contour maps along with the associated sets of spherical harmonic coefficients form a valuable data set for studying different aspects of our changing climate over monthly, annual, and interannual scales in the time domain, and over regional, zonal, and global scales in the spatial domain

    Atlas of wide-field-of-view outgoing longwave radiation derived from Nimbus 7 Earth radiation budget data set - November 1978 to October 1985

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    An atlas of monthly mean outgoing longwave radiation global contour maps and associated spherical harmonic coefficients is presented. The atlas contains 84 months of continuous data from November 1978 to October 1985. The data were derived from the second Earth radiation budget experiment, which was flown on the Nimbus 7 Sun-synchronous satellite in 1978. This data set is a companion set and extension to a similar report of the Nimbus 6 satellite. Together these two reports give a data set covering a 10 year time period and will be very valuable in studying different aspects of our changing climate over monthly, annual, and interannual scales in the time domain and over regional, zonal, and global scales in the spatial domain

    Atlas of albedo and absorbed solar radiation derived from Nimbus 6 earth radiation budget data set, July 1975 to May 1978

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    An atlas of monthly mean global contour maps of albedo and absorbed solar radiation is presented. The atlas is based on 35 months of continuous measurements from July 1975 through May 1978. The data were retrieved from measurements made by the shortwave wide field-of-view radiometer of the first Earth Radiation Budget (ERB) instrument, which flew on the Nimbus 6 spacecraft in 1975. Profiles of zonal mean albedos and absorbed solar radiation are tabulated. These geographical distributions are provided as a resource for studying the radiation budget of the earth. This atlas of albedo and absorbed solar radiation complements the atlases of outgoing longwave radiation by Bess and Smith in NASA-RP-1185 and RP-1186, also based on the Nimbus 6 and 7 ERB data

    Atlas of albedo and absorbed solar radiation derived from Nimbus 7 Earth radiation budget data set, November 1978 to October 1985

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    An atlas of monthly mean global contour maps of albedo and absorbed solar radiation is presented. This atlas contains 7 years of continuous data from November 1978 through October 1985. The data were retrieved from measurements made by the second Earth Radiation Budget (ERB) wide field-of-view instrument, which flew on the Nimbus 7 spacecraft in 1978. The deconvolution method used to produce these data is briefly discussed here so that the user may understand their generation and limitations. These geographical distributions of albedo and absorbed solar radiation are provided as a resource for researchers studying the radiation budget of the Earth. This atlas of albedo and absorbed solar radiation complements the atlases of outgoing longwave radiation by Bess and Smith, also based on the Nimbus 6 and 7 ERB data

    Selected biological characteristics of Brachymeria ovata reared on live and freezer-stored pupae of the cabbage looper, Trichoplusia ni

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    Parasitoids can be an important part of a biological control program. The use of freezer-stored pupae has been suggested as a means to rear large numbers of parasitoids for release in biological control programs (Grant and Shepard 1987). Brachymeria ovata (Say) (Hymenoptera: Chalcididae) has been reared successfully from freezer-stored pupae of several noctuid species of lepidoptera (Grant and Shepard 1987); however, it was not known if the use of freezer-stored pupae as hosts of B. ovata had any affect on the biological characteristics of this parasitoid. A colony of B. ovata was maintained, and all experiments were conducted, utilizing the pupae of the cabbage looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae). Experiments were conducted at 27±2°C and 50 to 65%RH. The mating ability of individuals reared from freezer-stored pupae was not significantly impacted; however, a slight decrease in successful matings was observed when males were reared from freezer-stored pupae. The mean preovipositional period increased when individuals were reared from freezer-stored pupae. B. ovata generally parasitized pupae during the hours of light. The greatest number of parasitoids were produced during the first four-hour period of light and the number of progeny produced decreased throughout the day. Unmated female B. ovata individuals not exposed to hosts generally lived longer (114.0 and 135.8 days, respectively, when reared from live and freezerstored pupae) than unmated males (approximately 100 days), and those females reared from freezer-stored pupae lived significantly longer than females reared from live pupae. Paired adults lived for shorter periods than unmated B. ovata. Longevity of paired females exposed to live pupae was significantly shorter (approximately 15 days) than the longevity of males or females not exposed to live or freezer-stored pupae (approximately 60 to 86 days, respectively). Fecundity of B. ovata increased when females were exposed to freezerstored pupae. Those females reared on and exposed to freezer-stored pupae produced the greatest number of eggs (x =422.2). Females exposed to live pupae lived one fourth to one third as long when reared from live or freezerstored pupae, respectively, and produced an average of 91.3 and 137.2 eggs, respectively. Progeny production was significantly decreased when females were exposed to freezer-stored pupae. Females produced an average of 83.3 and 79.1 progeny when reared from live or freezer-stored pupae, respectively, and exposed to live pupae during their entire lifetime. Females exposed to freezerstored pupae produced significantly fewer progeny (x=31.9 and 37.3, respectively, when reared from live or freezer-stored pupae) during the first 14 days of oviposition. As the fecundity of individuals exposed to freezer-stored pupae is greater than that of ones exposed to live pupae, the potential exists for greater progeny production from females exposed to freezer-stored pupae. The acceptability of freezer-stored pupae was significantly lower than that of live pupae in terms of the percentage of pupae containing eggs (88.2% of live pupae and 71.4% of freezer-stored pupae) but the average number of eggs per pupa was not significantly different. The suitability of live and freezer-stored pupae in terms of the percentage of pupae supporting development of B. ovata to adulthood was significantly higher for live pupae (85.5%) than for freezer-stored pupae (23.0%) Higher levels of suitability were observed in other experiments utilizing freezer-stored pupae. The suitability of different age pupae, at time of freezing, and of live pupae also, was determined to be from two to five days after pupation. Many individuals reared on older pupae were smaller than those reared on pupae two to five days old. The production of small adults was probably a result of having less food available to the larva. The development of immature stages of B. ovata in freezer-stored pupae was lengthened from two to five days in the larval stage and about one day in the pupal stage. Overall freezer-stored pupae did not detrimentally impact upon the biological characteristics of B. ovata. With increased suitability of freezer-stored pupae as observed in some experiments conducted in this study as well as others (Grant and Shepard 1987), it should be economically advantageous to use freezer-stored pupae as a host for B. ovata

    Sediments and Structures of Part of Glacial Lake Agassiz in Grand Forks County, North Dakota

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    Eastern Grand Forks County lies within the glacial Lake Agassiz plain (Fig.2). The lacustrine sediments, as exposed in a drainage ditch along the east edge of sections 16, 21, and 28, T. 154 N., R. 52 W., northwest of Manvel, North Dakota, have been divided into two main groups: the lower bedded clays overlain by bedded, silty clays and silt. Separating these units is a limonite hardpan. During the late receding stage of Lake Agassiz, tributary drainage developed cut and filled channels within the silt directly underlying the lake plain. Several such channels occur within the outcrop area in the upper three feet of Lake Agassiz sediments. Folding of these sediments by isostatic rebound accounts for the distorted sediments noted in the outcrop. Size analyses prove these sediments are of lacustrine origin and that the channel structures are fluvial. Buried wood suggests an erosional interval during the closing stages of Lake Agassiz

    Strandline and Sediment Analysis of Stump Lake Area, Nelson County, North Dakota

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    The purpose of this paper is to describe and interpret the late glacial and Recent history of Stump Lake, a closed basin lake, in Helson County, North Dakota, T. 151 N., R. 60 W. (see fig . 1). The work was started as a summer project under a National Science Foundation Undergraduate Research Participation Program and completed for credit in Geologic Problems 421. The research began in July, 1967, after several weeks of familiarization with field techniques and problems associated with glacial terrain. The project included mapping, leveling, and analysis of strandlines and their sediments
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