17 research outputs found

    Deconstructing Conformal Blocks in 4D CFT

    Get PDF
    We show how conformal partial waves (or conformal blocks) of spinor/tensor correlators can be related to each other by means of differential operators in four dimensional conformal field theories. We explicitly construct such differential operators for all possible conformal partial waves associated to four-point functions of arbitrary traceless symmetric operators. Our method allows any conformal partial wave to be extracted from a few \u201cseed\u201d correlators, simplifying dramatically the computation needed to bootstrap tensor correlators. \ua9 2015, The Author(s)

    Seasonal variation of carbon fluxes in a sparse savanna in semi arid Sudan

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Large spatial, seasonal and annual variability of major drivers of the carbon cycle (precipitation, temperature, fire regime and nutrient availability) are common in the Sahel region. This causes large variability in net ecosystem exchange and in vegetation productivity, the subsistence basis for a major part of the rural population in Sahel. This study compares the 2005 dry and wet season fluxes of CO<sub>2 </sub>for a grass land/sparse savanna site in semi arid Sudan and relates these fluxes to water availability and incoming photosynthetic photon flux density (PPFD). Data from this site could complement the current sparse observation network in Africa, a continent where climatic change could significantly impact the future and which constitute a weak link in our understanding of the global carbon cycle.</p> <p>Results</p> <p>The dry season (represented by Julian day 35–46, February 2005) was characterized by low soil moisture availability, low evapotranspiration and a high vapor pressure deficit. The mean daily NEE (net ecosystem exchange, Eq. 1) was -14.7 mmol d<sup>-1 </sup>for the 12 day period (negative numbers denote sinks, i.e. flux from the atmosphere to the biosphere). The water use efficiency (WUE) was 1.6 mmol CO<sub>2 </sub>mol H<sub>2</sub>O<sup>-1 </sup>and the light use efficiency (LUE) was 0.95 mmol CO<sub>2 </sub>mol PPFD<sup>-1</sup>. Photosynthesis is a weak, but linear function of PPFD. The wet season (represented by Julian day 266–273, September 2005) was, compared to the dry season, characterized by slightly higher soil moisture availability, higher evapotranspiration and a slightly lower vapor pressure deficit. The mean daily NEE was -152 mmol d<sup>-1 </sup>for the 8 day period. The WUE was lower, 0.97 mmol CO<sub>2 </sub>mol H<sub>2</sub>O<sup>-1 </sup>and the LUE was higher, 7.2 <it>ÎŒ</it>mol CO<sub>2 </sub>mmol PPFD<sup>-1 </sup>during the wet season compared to the dry season. During the wet season photosynthesis increases with PPFD to about 1600 <it>ÎŒ</it>mol m<sup>-2</sup>s<sup>-1 </sup>and then levels off.</p> <p>Conclusion</p> <p>Based on data collected during two short periods, the studied ecosystem was a sink of carbon both during the dry and wet season 2005. The small sink during the dry season is surprising and similar dry season sinks have not to our knowledge been reported from other similar savanna ecosystems and could have potential management implications for agroforestry. A strong response of NEE versus small changes in plant available soil water content was found. Collection and analysis of flux data for several consecutive years including variations in precipitation, available soil moisture and labile soil carbon are needed for understanding the year to year variation of the carbon budget of this grass land/sparse savanna site in semi arid Sudan.</p

    Author Correction: The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data

    Full text link
    The following authors were omitted from the original version of this Data Descriptor: Markus Reichstein and Nicolas Vuichard. Both contributed to the code development and N. Vuichard contributed to the processing of the ERA-Interim data downscaling. Furthermore, the contribution of the co-author Frank Tiedemann was re-evaluated relative to the colleague Corinna Rebmann, both working at the same sites, and based on this re-evaluation a substitution in the co-author list is implemented (with Rebmann replacing Tiedemann). Finally, two affiliations were listed incorrectly and are corrected here (entries 190 and 193). The author list and affiliations have been amended to address these omissions in both the HTML and PDF versions

    The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data.

    Full text link
    The FLUXNET2015 dataset provides ecosystem-scale data on CO2, water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible

    2

    No full text
    Fourteen samples of L. dorsi muscles were taken from western Baggara cattle, one sample from each of seven bulls and seven heifers randomly selected for slaughter at the end of an experimental feedlot feeding which lasted for 16 weeks at Kuku Research Station, Khartoum North, Sudan, to study sex effects on meat chemical composition and quality attributes. Moisture content of beef was higher in bulls meat than in heifers meat. Protein and ash content were significantly (P&lt;0.001) higher in bulls meat, whereas fat content was significantly (P&lt;0.001) higher in heifers meat than in bulls meat. Cooking loss of bulls meat was significantly (P&lt;0.001) lower and water-holding capacity was also significantly (P&lt;0.01) lower in the bulls meat than in heifers meat. Bull’s meat colour had low lightness (L) and high redness (a) and yellowness (b), as determined by Hunter Lab. Tristimulus colorimeter, as compared with heifers meat. Sensory panelist scores were higher for colour darknes

    Characteristics of beef from intensively fed western Baggara cattle: carcass yield and composition

    No full text
    Sixteen heifers and an equal number of bull calves of western Baggara type were used to study the characteristics of carcass and wholesale cuts at Kuku Livestock Research Station, Khartoum North, Sudan. Each of the two sex groups was subdivided into 4 subgroups of 4 animals. All the animals were fed, ad libitum, a similar complete diet for 16 weeks from 4 November 2002 to 24 February 2003. Bulls carcass had significantly (P&lt; 0.05) greater proportion of forequarter than that of the heifers, whereas heifers carcass had significantly (P&lt; 0.05) greater proportion of hindquarter than that of the bulls. Heifer’s carcass had more primal cuts proportion than that of bulls, though the difference was not significant. Bulls carcass had significantly (P&lt; 0.001) greater muscle proportion and significantly (P&lt; 0.01) lower fat proportion in the forequarter than in that of heifers. Bone weight proportion of the heifers carcass forequarter was lower than that of the bulls, though the difference was not significant. Similarly hindquarter of the bulls carcass had higher proportion of muscle and bone, though the differences were not significant while the heifer carcasses hindquarter fat proportion was significantly (P&lt;0.01) higher compared with that of bull carcasses. No significant differences were found in the yield of wholesale cuts weight as % of carcass weight other than the neck, chuck and blade and rump. The former two cuts were significantly (P&lt;0.01) heavier in bull carcass, while the rump cut was significantly (P&lt;0.05) heavier in heifer carcass. The proportion of muscle weight of the cuts as % of carcass weight was generally higher in all cuts except in the shin and rump cuts obtained from bulls as compared wit

    Haematogenous dissemination of tuberculous lymphadentitis

    No full text
    No Abstract. The East African Medical Journal Vol. 84 (1) 2007: pp 3-

    The Association of Lymphocyte Count, CRP, D-Dimer, and LDH with Severe Coronavirus Disease 2019 (COVID-19): A Meta-Analysis

    Full text link
    Background: The rapid progression of Coronavirus disease 2019 (COVID-19) and its increasing burden on health systems necessitate the identification of parameters of severe infection to help in monitoring, prognoses and development of treatment algorithms. Objectives: This review aims to investigate the association of lymphocyte count, CRP, LDH, and D-Dimer with the severity of COVID-19. Methods: This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The databases of MEDLINE/PubMed, WHO-Virtual Health Library (VHL), and ScienceDirect were used for the systematic search. Random effects model was used to estimate the pooled standardized mean differences (SMD) with the corresponding 95% confidence interval (CI), using OpenMeta Analyst software. Results: A total of 11 studies, with 2437 COVID-19 patients, which fulfilled the eligibility criteria were included in the meta-analysis. The analysis revealed that lymphocyte count was significantly lower in patients with the severe form of COVID-19 (SMD = - 1.025, P value &lt;.001). Also, the analysis of SMD showed that patients with severe COVID-19 have a significantly higher serum levels of CRP (SMD = 3.363, P value &lt;.001), D-Dimer (SMD = 1.073, P value &lt;.001), and LDH (SMD = 3.345, P value &lt;.001). Conclusion: Low lymphocyte count and high levels of CRP, LDH, and D-Dimer are associated with severe COVID-19. These laboratory markers could be used as clinical indicators of worsening illness and poor prognosis of COVID-19
    corecore