There are three mail types of Botnet: IRC-based Botnet, P2P-based Botnet,Web-based Botnet and they have become major threat to the Internet recently. Web-based Botnet is popular and more harmful to users. The architecture of Web-based Botnet is simpler than P2P-based Botnet, and its malicious traffic can be hidden in a large number of normal traffic. In this study, we built an experimental environment of using malicious bot programs to detect suspicious traffic and malware features. Except network attacking and identity theft, Botnet could also be used by hackers to extend the life time of rouge websites by combining with the technology of Fast Flux Domain. Botnet and the technology of Fast Flux Domain closely link to each other in the real world. Both of Web-based Botnet and Fast Flux Domain technology use HTTP protocol to communicate, and Botnet provides a large number of infected hosts to be Fast Flux Agents which act like a relay station to block the direct link of malicious websites from clients, but completes the mutual connection. In the research, not only the analysis and detection of Web-based Botnet are focused, but also the impact of Fast Flux Domain technology is included. We expect to clear the architecture of Botnet and the technology of Fast Flux Domain, and make the detection mechanism more precisely.

BiFeO3, a material with coexistence of antiferromagnetic and ferroelectric phases at room temperature, has been expecting to be used on novel devices such as FeRAM and spintronics. In this research, it is found that the surface morphologies of SrTiO3 influence the subsequence growth of SrRuO3 and Pb-dopant BiFeO¬3 (PBFO) films. The domain structures are associated to various surface structure and different thickness of PBFO investigated by a piezoresponse force microscopy. The radial-polarization-like domains was found on the PBFO island structures, and the domain size and the remnant piezoresponse increases with the thickness increasing; in contrary, the shifting of the electric coercive field occurs in the thinner films.

Modern search engines like Google support domain-independent search over the vast information contained in web documents. However domain-specific information access, such as finding less well-known people, locations, and events are not performed efficiently without users developing sophisticated query strategies. This thesis describes the design and development of an application to support one such domain-specific information activity: for insurance (and related) companies to identify weather and natural disaster damage to better assess when and where personnel will be needed. The approach presented to supporting such activity combines information extraction with an interactive presentation of results. Previous domain specific search engines extract information about papers, people, and course information using rule-based or learningbased techniques. However they use the results of information extraction in a typical query and list of results interface. They fail to address the need for interaction based on the extracted document features. The domain specific web-based search application developed in this project combines information extraction with the interactive display of results to facilitate rapid information location. A heuristic evaluation was performed to determine whether the application met the design goals and to improve the design. Thus the final application has an unconventional but interactive presentation of the results with the use of tree based display. The application also allows options for user specific results caching and modification of the search and caching process. With a heuristic based search process it extracts information about place, date and damages regarding a specific disaster using a bank of search heuristics developed.

Lysis of the host by bacteriophage 21 requires two proteins: the pinholin S21 (forms pinholes in the cytoplasmic membrane and controls lysis timing) and the endolysin (degrades the cell wall). S21 has a dual-start motif, encoding a holin, S2168, and a weak antiholin, S2171. Both proteins have two transmembrane domains (TMD) and adopt an N-in, C-in topology. The topology of S2168 is dynamic because TMD1 is a signal-anchor-release (SAR) domain which, while initially integrated into the cytoplasmic membrane, is eventually released into the periplasm. TMD1 is dispensable because the truncated protein, S2168?TMD1, retains the holin function. Adding two positive charges to N-terminus of S2168 by an irs tag (RYIRS) prevents the release of TMD1. The irsS2168 protein not only has lost its holin function, but is a potent antiholin and blocks the function of S2168. In this dissertation, the structure of S2168 was suggested by incorporating electron-microscopy, biochemical, and computational approaches. The results suggest that S2168 forms a symmetric heptamer, with the hydrophilic side of TMD2 lining the channel of ~ 15 A in diameter. This model also identifies two interacting surfaces, A and B, of TMD2. A model for the pinhole formation pathway was generated from analyzing phenotypes of an extensive collection of S21 mutants. In this model, the individually folded and inserted S21 molecules first form the inactive dimer, with the membrane-inserted TMD1 inhibiting the lethal function of TMD2 both inter- and intra-molecularly. A second inactive dimer may form, with one TMD1 released. When both TMD1s are released, the activated dimer is formed, with the homotypic interfaces A:A interaction of the TMD2s. However, this interaction might not be stable, which will shift to heterotypic A:B interactions, allowing TMD2 to oligomerize. Finally, the pinhole forms, possibly driven by the hydration of lumenal hydrophilic residues. In addition, the localization of pinholes was visualized by fusing the green fluorescent protein (GFP) to the C-terminus of pinholins. The results showed that pinholins form numerous small aggregates, designated as rafts, spread all over the cell body. The antiholin irsS2168 not only inhibits the triggering of S2168GFP, but inhibits the rafts formation as well.

In addition to AtCPL1-4, the genome of Arabidopsis thaliana encodes a large number of putative acid phosphatases. The predicted Arabidopsis SCP1-like small phosphatases (SSP) are highly homologous to the catalytic domain of eukaryotic RNA polymerase II carboxyl terminal domain (pol II CTD) phosphatases. Among the family members, SSP4, SSP4b and SSP5 form a unique group characterized by long N-terminal extensions. These three SSPs showed similar and ubiquitous gene expression. SSP4 and SSP4b were localized exclusively in the nuclei, while SSP5 accumulated both in the nucleus and cytoplasm. In vitro observation revealed that SSP4 and SSP4b dephosphorylated the pol II CTD-PO4 at both Ser2 and Ser5 in the conserved heptad repeats; however, SSP5 dephosphorylated only Ser5 of CTD-PO4. These results indicate that Arabidopsis SSP family encodes active CTD phosphatases similarly to animal SCP1 family proteins and plant CPLs family proteins, but with distinct substrate specificities. ssp mutants did not exhibit phenotypic abnormalities under normal growth conditions. However, ssp5 single mutants and ssp4 ssp4b ssp5 triple mutants showed enhanced sensitivity to ABA and glucose during seed germination. Yet, increased ABA-inducible gene expressions were not distinguishable in triple mutants compared to wild type plants upon ABA treatment. Unlike the ssp mutations, the cpl1 mutation strongly induced RD29A expression in response to cold, ABA and NaCl treatments. Thus, the cpl1 mutant is an ideal genetic background for an inducible gene expression system, in which the detrimental effect to host plants caused by a conventional constitutive expression could be avoided. Production of flavonoid such as anthocyanins in Arabidopsis is relatively easy to monitor and is regulated by transcription factors such as PAP1. PAP1 activates the expression of multiple enzymes in the anthocyanin biosynthesis pathway; however, high level of flavonoid production could cause vegetative growth retardation. To optimize flavonoid accumulation, a three-component system was designed consisting of a cold inducible RD29A-PAP1 expression cassette, a feedforward effector RD29A-CBF3, and a mutation in host repressor CPL1. Transgenic cpl1 plants containing both homozygous PAP1 and CBF3 transgenes produced 30-fold higher level of total anthocyanins than control plants upon cold treatment. LC/MS/MS analysis showed the flavonoid profile in cold-induced transgenic plants resembled that of previously reported pap1-D plants but were enriched for kaempferol derivatives. Furthermore, PAP1 and environmental signals synergistically regulate flavonoid pathway to produce a flavonoid blend that has not been produced by PAP1 overexpression or cold treatment alone. These results delineate the usability of the three-component inducible system in plant metabolic engineering.

It is well known that the finite difference time domain (FDTD) method is a powerful numerical analysis tool for solving electromagnetic problems. In a simulated area, in order to discretize an object which is much smaller than the others, a very small space increment is needed and hence the time step should be decreased too for stability consideration in traditional FDTD. The small space and time increments will respectively increase the memory requirement and calculation time. To overcome these problems, some numerical methods were developed, such as the subcell and nonuniform grid method, to handle the small feature size. This thesis describes an efficient method for generating FDTD subcell equations. We construct a second order macromodel system instead of the subcell region in conventional FDTD. The macromodel system can be reduced with model order reduction techniques (MOR) and then translated into new FDTD update equations. When the problem contains several objects of the same size and material properties, the MOR subcell has the advantage of reusability. This means that the reduce-order model of the object needs to be generated only once nonetheless can be applied to every position where the objects originally occupied.

¡@¡@e-Learning is becoming more and more important for many educational institutions, and many educators believe that there is a good potential for providing adaptive learning in e-learning environment. In order to support the design of adaptive learning materials, teachers need to refer to the ontology of the subject domain to be taught. Moreover, ontology can show the whole picture and the core knowledge of a subject domain. Literature reviews also pointed out that graphical representation of ontology can reduce the problems of information overloading and learning disorientation for learners. However, ontology constructions all rely on domain experts in the past; it is a time consuming and high cost task. It would be more challenge for those emerging new domains like e-Learning. ¡@¡@e-Learning is a new and fast developing domain, how to automatic constructing its ontology is a very important topic. In this research, we use some relevant e-Learning journals and conferences papers as input data sources, and apply data mining techniques to automatically construct the concept maps for e-learning. We also analyzed the evolution in e-Learning domain according to the concept maps constructed at different time periods. ¡@¡@The contribution of this research is automatic constructing the concept maps of e-Learning domain using text-mining techniques. It can provide a comprehensive and useful reference for researchers to do research, for teachers to do adaptive course design and for learners to understand the related knowledge in e-Learning.

The hsFLJ22386 gene, an unknown gene, was located on chromosome 16p13.3. Its protein product contains 287 amino acids with the molecular weight of 32.2 kDa approximately. Predicted by bioinformatics, hsFLJ22386 might be a protein containing a leucine zipper domain. Based on the results of reverse transcriptase polymerase chain reaction, it revealed that FLJ22386 was expressed in several nervous system tissues and several organ tissues (liver, spleen, small intestine and kidney). In human cancer cell lines, the RT-PCR results showed that FLJ22386 was expressed in brain tumor cell lines (T98G, U87MG, U251, GBM8401), nasopharyngeal epithelial cell line (NNE-3)and carcinoma cell lines (NPCTW01, NPCTW04), hepatoma cell lines (J5, Hep3B, SK-Hep-1) and lymphoma cell lines (RPMI, P3HR1, Raji, U937). Human FLJ22386 coding sequence was inserted into pEGFP-C2 plasmid, and the tag-fused gene was transfected into NIH3T3 cells to see if it has the ability to promote cell proliferation. To further investigate the protein level expression and biological functions of the gene, glutathione S-transferase-hsFLJ22386 fusion protein was expressed and used to generate anti-FLJ22386 polyclonal antibody. According to the results of RT-PCR and anchorage dependent growth assay, it is presumed that FLJ22386 may play a role in cell proliferation.

¡@In this thesis, a novel subgridding scheme is proposed based on the hybridization of the FDTD and CNDG-FDTD algorithms. The FDTD method is applied to the coarse grid region, while the CNDG-FDTD method is used in the fine grid region. Because of the unconditional stability of the CNDG scheme, the temporal step size can be set equal to that in the coarse grid region to speed up the computation in the fine grid region. Furthermore, the temporal interpolation at the fine and coarse grids interface is no longer necessary and thus the complexity of spatial interpolation is largely reduced. ¡@As the CNDG-FDTD method is free from the CFL condition restraint, it saves a large amount of CPU time. Numerical results agree very well with that of the FDTD scheme. But it requires a larger amount of computer memory, at least 20% more than the FDTD method. A modified version of the CNDG-FDTD scheme with increased memory efficiency is also presented. It has not only eliminated the restraint of the CFL condition, but also achieved a more efficient saving of CPU time and computer memory requirements.

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