1,965 research outputs found

    ERBE and AVHRR Cirrus cloud fire study

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    Understanding the impact of cirrus clouds on the global radiation budget is essential to determining the role of clouds in the process of climate change. The ongoing Earth Radiation Budget Experiment (ERBE) is charged with measuring the global radiation balance at the top of the atmosphere. The International Satellite Cloud Climatology Project (ISCCP) is measuring global cloud amounts and properties over a time frame similar to ERBE. Specific cloud properties are absent from the ERBE program, while ISCCP lacks the broadband radiances necessary to determine the total radiation fields. Together, results from these two global programs have the potential for improving the knowledge of the relationship between cirrus clouds and the Earth radiation balance. The First ISCCP Regional Experiment (FIRE), especially its cirrus Intensive Field Observations (IFO), provides opportunities for studying radiation measurements from the ERBE taken over areas with known cirrus cloud properties. Satellite measurements taken during the IFO are used to determine the broadband radiation fields over cirrus clouds and to examine the relationship between narrowband and broadband radiances over various known scenes. The latter constitutes the link between the ERBE and the ISCCP

    Information Technology: A Study Of Ac-countants Skills And Knowledge Levels

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    This article examines the results of a survey mailed to 940 accounting professionals in which they identify the categories of IT skills and knowledge that are required to perform their job. Using cluster analysis, this article next examines whether - and to what extent -relationships exist between different categories of IT skills and knowledge. Survey results are then presented regarding methods by which accounting professionals acquire needed job-related IT skills and knowledge

    Nonstructural carbohydrate and element pools in globemallow (Sphaeralcea): defoliation effects and seasonal trends

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    Globemallows (Sphaeralcea spp.) are arid land forbs suitable for seeding with crested wheatgrass (Agropyron cristatum [L.] Gaertner). However, little is known about the quantitative role of total nonstructural carbohydrates (TNC) in relation to globemallow tolerance of grazing, or about seasonal dynamics of mineral elements. The objectives of this study were to compare TNC and element pools (concentration x biomass) in the roots, crowns, and shoots of clipped versus unclipped S. munroana (Dougl.) Spach. Seedlings of S. munroana were transplanted to a northern Utah field site in 1985. Interplanted crested wheatgrass provided a uniform competitive background. One-half of the globemallows were clipped to 5 cm on 10 May 1986 when stems were elongating and root and crown TNC pools were low. The remaining globemallows were not clipped. Root, crown, and shoot pools of TNC and elements (N, P, K, Ca, and Mg) were determined on 1 May, 20 May, 7 June, 11 July, 22 September, and 5 November 1986, and 29 May 1987. Defoliation did not affect shoot weights during a 1-year period. Experiment-long TNC and element pools also were not affected by clipping. Results indicate that S. munroana shoot recovery from a single spring grazing during a 1-year period would not be impaired by low root and crown TNC pools, and that TNC stored in the roots and crowns would account for only 7% of the regrowth produced. Furthermore, TNC and element pools of roots and crowns were generally constant from May to September but increased from September to November. TNC and element pools in shoots increased from May to September and then generally declined by November. TNC pools of roots and crowns declined during winter

    Early Eocene Arctic volcanism from carbonate-metasomatized mantle

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    Melilitite, nephelinite, basanite, and alkali basalt, along with phonolite differentiates, form the Freemans Cove Complex (FCC) in the south-eastern extremity of Bathurst Island (Nunavut, Canada). New 40Ar/39Ar chronology indicates their emplacement between ~ 56 and ~ 54 million years ago within a localized extensional structure. Melilitites and nephelinites, along with phonolite differentiates, likely relate to the beginning and end phases of extension, whereas alkali basalts were emplaced during a main extensional episode at ~ 55 Ma. The melilitites, nephelinites, and alkali basalts show no strong evidence for significant assimilation of crust, in contrast to some phonolites. Partial melting occurred within both the garnet- and spinel-facies mantle and sampled sources with He, O, Nd, Hf, and Os isotope characteristics indicative of peridotite with two distinct components. The first, expressed in higher degree partial melts, represents a relatively depleted component (“A”; 3He/4He ~ 8 RA, ΔNdi ~ + 3 ΔHfi ~ + 7, ÎłOsi ~ 0). The second was an enriched component (“B” 3He/4He + 70) sampled by the lowest degree partial melts and represents carbonate-metasomatized peridotite. Magmatism in the FCC shows that rifting extended from the Labrador Sea to Bathurst Island and reached a zenith at ~ 55 Ma, during the Eurekan orogeny. The incompatible trace-element abundances and isotopic signatures of FCC rocks indicate melt generation occurred at the base of relatively thin lithosphere at the margin of a thick craton, with no mantle plume influence. FCC melt compositions are distinct from other continental rift magmatic provinces worldwide, and their metasomatized mantle source was plausibly formed synchronously with emplacement of Cretaceous kimberlites. The FCC illustrates that the range of isotopic compositions preserved in continental rift magmas are likely to be dominated by temporal changes in the extent of partial melting, as well as by the timing and degree of metasomatism recorded in the underlying continental lithosphere

    The Anti-Inflammatory Reliever (AIR) Algorithm Study: a protocol for a single-group study of an AIR stepwise approach to the treatment of adult asthma

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    Background The stepwise approach to long-term asthma management, which traditionally incorporates short-acting ÎČ2-agonist reliever therapy, has been a core feature of asthma guidelines for over 30 years. There have been no studies, however, directly investigating the use of an entire guideline-recommended track. Recently, inhaled corticosteroid–formoterol has been recommended as the preferred reliever therapy in adult asthma, in accordance with a stepwise “Anti-Inflammatory Reliever” (AIR) treatment track. Objective The aim of this study was to evaluate the AIR stepwise approach recommended by the New Zealand adolescent and adult asthma guidelines, in combination with a novel algorithm for transitioning between treatment steps. Methods This 52-week, open-label, single-group study will recruit 100 adults aged 18 to 75 years with mild, moderate and moderate–severe asthma (ACTRN12620001010987). Participants will be allocated to budesonide–formoterol 200/6 ”g, one actuation as needed (Step 1), one actuation twice daily and as needed (Step 2), or two actuations twice daily and one as needed (Step 3). Treatment steps will be adjusted throughout the study, in response to reliever use and asthma attacks, according to a stepwise AIR algorithm. Following a 26-week period of investigator-led transitions, participants will adjust their own treatment step. The primary outcome is participant satisfaction as measured by the Global Satisfaction score of the Treatment Satisfaction Questionnaire for Medication. Secondary outcomes will assess efficacy and safety, and describe patterns of medication use and participant flow through the treatment steps. Conclusion This is the first trial to assess the AIR treatment track and algorithm. The results will provide knowledge to guide the clinical use of this approach

    Bacteriocin-mediated competition in cystic fibrosis lung infections

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    Bacteriocins are toxins produced by bacteria to kill competitors of the same species. Theory and laboratory experiments suggest that bacteriocin production and immunity play a key role in the competitive dynamics of bacterial strains. The extent to which this is the case in natural populations, especially human pathogens, remains to be tested. We examined the role of bacteriocins in competition using Pseudomonas aeruginosa strains infecting lungs of humans with cystic fibrosis (CF). We assessed the ability of different strains to kill each other using phenotypic assays, and sequenced their genomes to determine what bacteriocins (pyocins) they carry. We found that (i) isolates from later infection stages inhibited earlier infecting strains less, but were more inhibited by pyocins produced by earlier infecting strains and carried fewer pyocin types; (ii) this difference between early and late infections appears to be caused by a difference in pyocin diversity between competing genotypes and not by loss of pyocin genes within a lineage over time; (iii) pyocin inhibition does not explain why certain strains outcompete others within lung infections; (iv) strains frequently carry the pyocin-killing gene, but not the immunity gene, suggesting resistance occurs via other unknown mechanisms. Our results show that, in contrast to patterns observed in experimental studies, pyocin production does not appear to have a major influence on strain competition during CF lung infections

    A comprehensive study of GRB 070125, a most energetic gamma ray burst

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    We present a comprehensive multiwavelength analysis of the bright, long duration gamma-ray burst GRB 070125, comprised of observations in γ\gamma-ray, X-ray, optical, millimeter and centimeter wavebands. Simultaneous fits to the optical and X-ray light curves favor a break on day 3.78, which we interpret as the jet break from a collimated outflow. Independent fits to optical and X-ray bands give similar results in the optical bands but shift the jet break to around day 10 in the X-ray light curve. We show that for the physical parameters derived for GRB 070125, inverse Compton scattering effects are important throughout the afterglow evolution. While inverse Compton scattering does not affect radio and optical bands, it may be a promising candidate to delay the jet break in the X-ray band. Radio light curves show rapid flux variations, which are interpreted as due to interstellar scintillation, and are used to derive an upper limit of 2.4×10172.4 \times 10^{17} cm on the radius of the fireball in the lateral expansion phase of the jet. Radio light curves and spectra suggest a high synchrotron self absorption frequency indicative of the afterglow shock wave moving in a dense medium. Our broadband modeling favors a constant density profile for the circumburst medium over a wind-like profile (R−2R^{-2}). However, keeping in mind the uncertainty of the parameters, it is difficult to unambiguously distinguish between the two density profiles. Our broadband fits suggest that \event is a burst with high radiative efficiency (>60> 60 %).Comment: 50 pages, 33 figures, sty file included, Appeared in 20 Aug 2008 edition of Astrophysical Journa
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