7,511 research outputs found
A Review of Global Precipitation Data Sets: Data Sources, Estimation, and Intercomparisons
In this paper, we present a comprehensive review of the data sources and estimation methods of 30 currently available global precipitation data sets, including gauge-based, satellite-related, and reanalysis data sets. We analyzed the discrepancies between the data sets from daily to annual timescales and found large differences in both the magnitude and the variability of precipitation estimates. The magnitude of annual precipitation estimates over global land deviated by as much as 300 mm/yr among the products. Reanalysis data sets had a larger degree of variability than the other types of data sets. The degree of variability in precipitation estimates also varied by region. Large differences in annual and seasonal estimates were found in tropical oceans, complex mountain areas, northern Africa, and some high-latitude regions. Overall, the variability associated with extreme precipitation estimates was slightly greater at lower latitudes than at higher latitudes. The reliability of precipitation data sets is mainly limited by the number and spatial coverage of surface stations, the satellite algorithms, and the data assimilation models. The inconsistencies described limit the capability of the products for climate monitoring, attribution, and model validation
A teacher's role in making a given knowledge curriculum into a powerful knowledge curriculum
Through examining the case of one senior high school geography teacher who has an understanding of powerful knowledge, this article presents the possibility of making a given geographical knowledge-based curriculum into a powerful geographical knowledge-based curriculum in China. The article argues that a curriculum based on powerful geographical knowledge can avoid the dangers anticipated with the ongoing competencies- based geography curriculum reform in China. In addition, the article demonstrates how the case study teacherâs pedagogical practice echoes some of the principles of Bernsteinâs notion of âvisible pedagogiesâ, namely strong classiďŹcation strong framing (+C+F). The article discusses how âvisible pedagogiesâ could provide an approach to the absence of pedagogy in a powerful knowledge-based curriculum. The article argues that it is within the power of individual teachers to use âvisible pedagogiesâ to make a given knowledge-based curriculum into a powerful knowledge-based curriculum
Synergistic Effects of Branched-chain Amino Acids and Phenylalanine Addition on Major Volatile Compounds in Wine during Alcoholic Fermentation
The effects of adding branched-chain amino acids (BCAAs, including L-valine, L-leucine and L-isoleucine),L-phenylalanine and a mixture of them (BCAAs + Phe) on the fermentation profiles of wine yeastEC1118 and the production of volatile compounds were investigated in synthetic grape juice. The additionof selected amino acids had no considerable influence on the yeast growth and primary metabolites of thesugars. Adding BCAAs increased the production of higher alcohols, medium-chain fatty acids (MCFAs)and their corresponding ethyl esters. In comparison, adding Phe promoted the production of 2-phenylethanol,2-phenylethyl acetate and ethyl esters of MCFAs. Nevertheless, the supplementation of BCAAs +Phe further heightened the production of MCFAs, acetate esters and ethyl esters of MCFAs compared tothe single additions, but it attenuated the production of various higher alcohols (1-propanol, 2,3-butanedioland methionol) compared to the addition of BCAAs, and of 2-phenylethanol and 2-phenylethyl acetatecontents compared to the Phe addition. These results suggest that adding BCAAs or Phe is an efficient wayto adjust wineâs aromatic composition and complexity. Meanwhile, the combined addition of BCAAs + Phecould be a potential tool to further manipulate wineâs aromatic profile by accentuating or suppressing theformation of certain aroma compounds
Characteristic Aroma Compounds in Two New Vitis vinifera Cultivars (Table Grapes) and Impact of Vintage and Greenhouse Cultivation
âZaoheibaoâ (a red tetraploid hybrid) and âWuhecuibaoâ (a white triploid hybrid) grapes have beenobtained from Guibaoâ (diploid, Vitis vinifera) Ă Zaomeiguiâ (diploid, V. vinifera) and Guibaoâ (diploid,V. vinifera) Ă Wuhebaijixinâ (triploid, V. vinifera) respectively. Aroma characterisation of the twonew table grape cultivars was firstly done by the investigation of volatile compounds. The influence ofgreenhouse cultivation and vintage on berry aroma was studied as well. The results showed that linalool,decanal, β-damascenone, hexanal and (E)-2-hexenal were the main volatile compounds of the two cultivars,which meant that the floral, fruity and sweet odour were prominent, followed by the herbaceous aroma.Greenhouse cultivation enhanced herbaceous odour in both âWuhecuibaoâ and âZaoheibaoâ berries,and reduced the floral aroma, contributed mainly by β-damascenone, in âWuhecuibaoâ, and the sweetaroma, represented mainly by linalool, in âZaoheibaoâ. The concentrations of the main aroma compoundswere greatly affected by vintage and the intensity of sensorial perception was correspondingly changed,but varietal odour attributes were not significantly altered. These results will not only help promote thecultivation and popularisation of these cultivars, but also will provide valuable data for the use of thesecultivars in future breeding
Comparison of Proanthocyanidins with Different Polymerisation Degrees among Berry Skins of âShirazâ, âCabernet Sauvignonâ, and âMarselanâ
Proanthocyanidins in grape berries are synthesised mainly before vĂŠraison, and very little attention ispaid to the evolution of proanthocyanidins (PAs) in grapes from vĂŠraison to harvest. The present studyfocused on the changes of flavan-3-ols with different degrees of polymerisation in grape skins and thedifference in proanthocyandin composition of âShirazâ, âCabernet Sauvignonâ and âMarselanâ grapes (Vitisvinifera L.). The results show that the content of flavan-3-ols, the percentage of prodelphinidins (%P)and mean degree polymerisation (mDP) found in âCabernet Sauvignonâ berry skins at post-vĂŠraison werehigher than those in âShirazâ and âMarselanâ skins. Only monomeric, dimeric, trimeric and polymericflavan-3-ols were detected in the three grape cultivars. Polymers with more than tenfold flavan-3-ol unitsaccounted for a relatively high proportion in grape berry skins, and the content in the three cultivarsdeclined continuously during ripening. Principal component analysis showed that proanthocyanidincontent, composition and mDP at grape harvest stage depended strongly on grape cultivar. This studyprovides some useful information for understanding the accumulation of PAs during berry maturationand this information can be used to improve wine quality
Tissue-specific Accumulation of Flavonoids in Grape Berries is Related to Transcriptional Expression of VvF3â˛H and VvF3â˛5â˛H
The products and the related gene expression of flavonoid metabolism were examined in the skin and pulpof Yan73 (Vitis vinifera L. cv.) grapes, a teinturier variety cultivated in China, and the data were comparedwith those in the skin and pulp of Cabernet Sauvignon (Vitis vinifera L. cv.) grapes, a well-known redvariety. The results showed that, in comparison with the skins of Cabernet Sauvignon, the skins of Yan73berries were characterised by fewer types of flavonols and anthocyanins, a higher level of flavonoids,and a much lower percentage of 3â˛-hydroxylated flavonols. Flavonoid metabolism was also present in thepulp of Yan73, and the percentages of 3â˛-hydroxylated flavonols and 3â˛-hydroxylated flavan-3-ols weresignificantly higher than the percentages of their corresponding 3â˛,5â˛-hydroxylated forms. Only flavan-3-ols were found in the pulp of Cabernet Sauvignon. The expression of VvmybA1 exhibited a co-ordinationwith the accumulation of anthocyanins in the pulp of the teinturier cultivar, which showed great similarityto that in the skin. A good correlation was found between the expression of VvF3â˛H and 3â˛-hydroxylatedflavonoids, as well as between the expression of VvF3â˛5â˛H and 3â˛,5â˛-hydroxylated flavonoids in the skin andpulp of the grape berries. It is suggested that tissue-specific accumulation of flavonoids in grape berries isrelated to the transcriptional expression of VvF3â˛H and VvF3â˛5â˛H
Changes of 3-Alkyl-2-methoxypyrazines in Developing Cabernet Sauvignon (Vitis vinifera) and Zuoshanyi (Vitis amurensis Rupr.) Grapes from North China
Changes in 3-alkyl-2-methoxypyrazines (MPs) in Cabernet Sauvignon (Vitis vinifera) and Zuoshanyi(Vitis amurensis Rupr.) grapes from different areas of North China were monitored throughout berrydevelopment in 2010. One kind of MP, 3-isobutyl-2-methoxypyrazine (IBMP), was detected in CabernetSauvignon grapes, and its content in grapes from Gaotai County was much higher than in those from theother two producing areas at the stages of vĂŠraison and maturity. Zuoshanyi grapes contained much moreIBMP than Cabernet Sauvignon grapes, and an additional kind of MP, 3-isopropyl-2-methoxypyrazine(IPMP), was also detected in developing Zuoshanyi grapes. Abundant MPs might explain the strongerâgreenâ and âherbaceousâ characters in Zuoshanyi grapes. MPs accumulated in the early developmentalstage in both Zuoshanyi and Cabernet Sauvignon grapes and rapidly decreased in the later stages. Delaysin the time of harvest for Cabernet Sauvignon in Gaotai County and Zuoshanyi in Beijing are suggested inorder to reduce MPs levels and the herbaceous character of these grapes
Mobility-aware multi-user offloading optimization for Mobile Edge Computing
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordMobile Edge Computing (MEC) is a new computing paradigm with great potential to enhance the performance of user equipment (UE) by offloading resource-hungry computation tasks to lightweight and ubiquitously deployed MEC servers. In this paper, we investigate the problem of offloading decision and resource allocation among multiple users served by one base station to achieve the optimal system-wide user utility, which is defined as a trade-off between task latency and energy consumption. Mobility in the process of task offloading is considered in the optimization. We prove that the problem is NP-hard and propose a heuristic mobility-aware offloading algorithm (HMAOA) to obtain the approximate optimal offloading scheme. The original global optimization problem is converted into multiple local optimization problems. Each local optimization problem is then decomposed into two subproblems: a convex computation allocation subproblem and a non-linear integer programming (NLIP) offloading decision subproblem. The convex subproblem is solved with a numerical method to obtain the optimal computation allocation among multiple offloading users, and a partial order based heuristic approach is designed for the NLIP subproblem to determine the approximate optimal offloading decision. The proposed HMAOA is with polynomial complexity. Extensive simulation experiments and comprehensive comparison with six baseline algorithms demonstrate its excellent performance
Generation of 3-Dimensional graph state with Josephson charge qubits
On the basis of generations of 1-dimensional and 2-dimensional graph states,
we generate a 3-dimensional N3-qubit graph state based on the Josephson charge
qubits. Since any two charge qubits can be selectively and effectively coupled
by a common inductance, the controlled phase transform between any two-qubit
can be performed. Accordingly, we can generate arbitrary multi-qubit graph
states corresponding to arbitrary shape graph, which meet the expectations of
various quantum information processing schemes. All the devices in the scheme
are well within the current technology. It is a simple, scalable and feasible
scheme for the generation of various graph states based on the Josephson charge
qubits.Comment: 4 pages, 4 figure
- âŚ