631 research outputs found
窒素リッチ排水の高効率処理に用いる担体流動床型アナッモクスプロセスの開発
要約のみTohoku University李玉友課
Quality modelling and metrics of Web-based information systems
In recent years, the World Wide Web has become a major platform for software
applications. Web-based information systems have been involved in many areas of
our everyday life, such as education, entertainment, business, manufacturing,
communication, etc. As web-based systems are usually distributed, multimedia,
interactive and cooperative, and their production processes usually follow ad-hoc
approaches, the quality of web-based systems has become a major concern.
Existing quality models and metrics do not fully satisfy the needs of quality
management of Web-based systems. This study has applied and adapted software
quality engineering methods and principles to address the following issues, a quality
modeling method for derivation of quality models of Web-based information systems;
and the development, implementation and validation of quality metrics of key quality
attributes of Web-based information systems, which include navigability and
timeliness.
The quality modeling method proposed in this study has the following strengths. It is
more objective and rigorous than existing approaches. The quality analysis can be
conducted in the early stage of system life cycle on the design. It is easy to use and
can provide insight into the improvement of the design of systems. Results of case
studies demonstrated that the quality modeling method is applicable and practical.
Practitioners can use the modeling method to develop their own quality models.
This study is amongst the first comprehensive attempts to develop quality
measurement for Web-based information systems. First, it identified the relationship
between website structural complexity and navigability. Quality metrics of
navigability were defined, investigated and implemented. Empirical studies were
conducted to evaluate the metrics. Second, this study investigated website timeliness
and attempted to find direct and indirect measures for the quality attribute. Empirical
studies for validating such metrics were also conducted.
This study also suggests four areas of future research that may be fruitful
Profits Optimization in the Supply Chain of Online Game Industry
Online game is a typical E-business indusry. Firstly, the problem is pointed out that the present researches on supply chain contracts designed for tangible traditional products have not considered the characteristic of intangible products such as online game industry. Secondly, the members and operation progress of the supply chain are explored in online game industry. Thirdly, a new supply chain contract model is provided for online game industry under the reference to the existed contracts models. At last, a mathematical example is provided, the profits for the whole supply chain and the profits for every member have been compared with between in the new contract model and in the old contract model, and the results shows the new contract model is better
PhOBF1, a petunia ocs element binding factor, plays an important role in antiviral RNA silencing.
Virus-induced gene silencing (VIGS) is a common reverse genetics strategy for characterizing the function of genes in plants. The detailed mechanism governing RNA silencing efficiency triggered by viruses is largely unclear. Here, we reveal that a petunia (Petunia hybrida) ocs element binding factor, PhOBF1, one of the basic leucine zipper (bZIP) transcription factors, was up-regulated by Tobacco rattle virus (TRV) infection. Simultaneous silencing of PhOBF1 and a reporter gene, phytoene desaturase (PDS) or chalcone synthase (CHS), by TRV-based VIGS led to a failure of the development of leaf photobleaching or the white-corollas phenotype. PhOBF1 silencing caused down-regulation of RNA silencing-related genes, including RNA-dependent RNA polymerases (RDRs), Dicer-like RNase III enzymes (DCLs), and Argonautes (AGOs). After inoculation with the TRV-PhPDS, PhOBF1-RNAi lines exhibited a substantially impaired PDS silencing efficiency, whereas overexpression of PhOBF1 resulted in a recovery of the silencing phenotype (photobleaching) in systemic leaves. A compromised resistance to TRV and Tobacco mosaic virus was found in PhOBF1-RNAi lines, while PhOBF1-overexpressing lines displayed an enhanced resistance to their infections. Compared with wild-type plants, PhOBF1-silenced plants accumulated lower levels of free salicylic acid (SA), salicylic acid glucoside, and phenylalanine, contrarily to higher levels of those in plants overexpressing PhOBF1. Furthermore, transcripts of a number of genes associated with the shikimate and phenylpropanoid pathways were decreased or increased in PhOBF1-RNAi or PhOBF1-overexpressing lines, respectively. Taken together, the data suggest that PhOBF1 regulates TRV-induced RNA silencing efficiency through modulation of RDRs, DCLs, and AGOs mediated by the SA biosynthesis pathway
Calibration of physically-based distributed rainfall-runoff model with radar data
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1995.Includes bibliographical references (leaves 119-122).by Yanlong Zhang.M.S
Asymptotically Efficient Quasi-Newton Type Identification with Quantized Observations Under Bounded Persistent Excitations
This paper is concerned with the optimal identification problem of dynamical
systems in which only quantized output observations are available under the
assumption of fixed thresholds and bounded persistent excitations. Based on a
time-varying projection, a weighted Quasi-Newton type projection (WQNP)
algorithm is proposed. With some mild conditions on the weight coefficients,
the algorithm is proved to be mean square and almost surely convergent, and the
convergence rate can be the reciprocal of the number of observations, which is
the same order as the optimal estimate under accurate measurements.
Furthermore, inspired by the structure of the Cramer-Rao lower bound, an
information-based identification (IBID) algorithm is constructed with adaptive
design about weight coefficients of the WQNP algorithm, where the weight
coefficients are related to the parameter estimates which leads to the
essential difficulty of algorithm analysis. Beyond the convergence properties,
this paper demonstrates that the IBID algorithm tends asymptotically to the
Cramer-Rao lower bound, and hence is asymptotically efficient. Numerical
examples are simulated to show the effectiveness of the information-based
identification algorithm.Comment: 16 pages, 3 figures, submitted to Automatic
Tree Peony Species Are a Novel Resource for Production of α-Linolenic Acid
Tree peony is known worldwide for its excellent ornamental and medical values, but recent reports that their seeds contain over 40% α-linolenic acid (ALA), an essential fatty acid for humans drew additional interest of biochemists. To understand the key factors that contribute to this rich accumulation of ALA, we carried out a comprehensive study of oil accumulation in developing seeds of nine wild tree peony species. The fatty acid content and composition was highly variable among the nine species; however, we selected a high- (P. rockii) and low-oil (P. lutea) accumulating species for a comparative transcriptome analysis. Similar to other oilseed transcriptomic studies, upregulation of select genes involved in plastidial fatty acid synthesis, and acyl editing, desaturation and triacylglycerol assembly in the endoplasmic reticulum was noted in seeds of P. rockii relative to P. lutea. Also, in association with the ALA content, transcript levels for fatty acid desaturases (SAD, FAD2 and FAD3), which encode for enzymes necessary for polyunsaturated fatty acid synthesis were higher in P. rockii compared to P. lutea. We further showed that the overexpression of PrFAD2 and PrFAD3 in Arabidopsis increased linoleic and α-linolenic acid content, respectively and modulated their final ratio in the seed oil. In conclusion, we identified the key steps that contribute to efficient ALA synthesis and validated the necessary desaturases in P. rockii that are responsible for not only increasing oil content but also modulating 18:2/18:3 ratio in seeds. Together, these results will aid to improve essential fatty acid content in seeds of tree peonies and other crops of agronomic interest
A petunia ethylene-responsive element binding factor, PhERF2, plays an important role in antiviral RNA silencing.
Virus-induced RNA silencing is involved in plant antiviral defense and requires key enzyme components, including RNA-dependent RNA polymerases (RDRs), Dicer-like RNase III enzymes (DCLs), and Argonaute proteins (AGOs). However, the transcriptional regulation of these critical components is largely unknown. In petunia (Petunia hybrida), an ethylene-responsive element binding factor, PhERF2, is induced by Tobacco rattle virus (TRV) infection. Inclusion of a PhERF2 fragment in a TRV silencing construct containing reporter fragments of phytoene desaturase (PDS) or chalcone synthase (CHS) substantially impaired silencing efficiency of both the PDS and CHS reporters. Silencing was also impaired in PhERF2- RNAi lines, where TRV-PhPDS infection did not show the expected silencing phenotype (photobleaching). In contrast, photobleaching in response to infiltration with the TRV-PhPDS construct was enhanced in plants overexpressing PhERF2 Transcript abundance of the RNA silencing-related genes RDR2, RDR6, DCL2, and AGO2 was lower in PhERF2-silenced plants but higher in PhERF2-overexpressing plants. Moreover, PhERF2-silenced lines showed higher susceptibility to Cucumber mosaic virus (CMV) than wild-type (WT) plants, while plants overexpressing PhERF2 exhibited increased resistance. Interestingly, growth and development of PhERF2-RNAi lines were substantially slower, whereas the overexpressing lines were more vigorous than the controls. Taken together, our results indicate that PhERF2 functions as a positive regulator in antiviral RNA silencing
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