126 research outputs found
Optimized Public Auditing and Data Dynamics for Data Storage Security in Cloud Computing
No full textAbstractCloud Computing is a promising service platform to access computing resources on demand over the Internet. It moves the data and applications to the large data centres where data and services can be managed in a much better manner than locally. However, its use puts forth a lot of challenging issues related to security, privacy and reliability of the overall system. In this paper, we focus on the problem of data-integrity verification(by a third party auditor) for the client's data residing on a cloud storage server(CSS). Here, we optimize an existing third party auditing protocol and make it resistant to replace, replay and forge attacks launched by malicious insiders at cloud storage server. We also propose a protocol to perform efficient block-level and fine-grained dynamic-data update operations on data stored on cloud using a modified Chameleon Authentication Tree. Extensive security and performance analysis shows that our protocols are efficient and can resist aforementioned attacks
On Customized Goods, Standard Goods, and Competition
No full textIn this study, we examine firms' incentive to offer customized products in addition to their standard products in a competitive environment. We offer several key insights. First, we delineate market conditions in which firms will (will not) offer customized products in addition to their standard products. Surprisingly, we find that when firms offer customized products they are able to not only expand demand, but can also the prices of their standard products relative to when they do not. Second, we find that when a firm offers customized products it is a dominant strategy for it to also offer its standard product. This result highlights the role of standard products and the importance of retaining them when firms offer customized products. Third, we identify market conditions under which ex ante symmetric firms will adopt symmetric or asymmetric customization strategies. Fourth, we highlight how the degree of customization offered in equilibrium is affected by market parameters. We find that the degree of customization is lower when both firms offer customized products relative to the case when only one firm offers customized products. Finally, we show that customizing products under competition does not lead to a prisoner's dilemma.degree of product customization, mass customization, standard products, competition, game theory
Síntese de derivados glicosídeos da di-hidrocucurbitacina B
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Farmácia, Florianópolis, 2014As cucurbitacinas são moléculas naturais para as quais são atribuídas diversas atividades biológicas. Na busca de um composto com potencial atividade antitumoral, este trabalho foi direcionado para a obtenção de derivados glicosilados de di-hidrocucurbitacina B (DHB). Nesse sentido, estratégias utilizadas na química medicinal, tais como modificação de grupos funcionais e extensão de cadeia foram utilizadas. Através de reação seletiva de oxidação em C-16, obteve-se o derivado de DHB 2, o qual foi submetido à reação de O-glicosilação com doadores monossacarídicos derivados de D-glicose (a), D-galactose (b), D-manose (c) e L-arabinose (d). Foram utilizadas diversas metodologias de O-glicosilação descritas na literatura, dentre elas, metodologias clássicas como Köenigs-Knorr, Helferich e Schmitd. O derivado galactosídeo 15 de DHB foi obtido com 3% de rendimento, através de reação do composto 2 e o doador monossacarídico tricloroacetimidato de galactose 9b, utilizando TMSOTf como promotor. O derivado azida de DHB 3 foi obtido em duas etapas, a partir do composto 2. Este produto, por sua vez, foi submetido à reação de cicloadição, para formação do anel 1,2,3-triazol-1,4-dissubstituído, com as séries de monossacarídeos contendo alcino terminal 10a-d e 18a-d. Os produtos 16a-d e 19a-d foram obtidos utilizando a estratégia de "Click Chemistry", suas estruturas foram confirmadas por espectroscopia de RMN, IV, e por espectrometria de massas de alta resolução (ESI-TOF). Os produtos 15, 16a-d e 19a-d são compostos inéditos e serão enviados para teste de atividade citotóxica frente à três linhagens de células tumorais.Abstract: Cucurbitacins are natural molecules to which are attributed many biological activities. In a search for a compound with potential antitumor activity, this work aims to obtain glycosylated derivatives of di-hidrocucurbitacina B (DHB). Thus, Medicinal Chemistry strategies, such as modification of functional groups and chain extension were used. DHB derivative 2 was obtained by selective oxidation reaction at C-16 position. O-glycosylation of 2 with the monosaccharidic donors derived from D-glucose (a) D-galactose (b) D-mannose (c) and L-arabinose (d) were performed. Different methodologies described in the literature, such as classical Koenigs-Knorr, Helferich and Schmitd reactions were tested. The galactoside DHB derivative 15 was obtained with 3% yield by reaction of compound 2 and trichloroacetimidate monosacharidic donor 9b, using TMSOTf as promoter. DHB azide derivative 3 was obtained in two steps from 2. The azide derivative were used for cycloaddition reaction to the formation of the 1,2,3-triazole ring ,1,4-disubstituted, with the series of monosaccharides containing terminal alkyne 10a-d and 18a-d. The products 16a-d and 19a-d were obtained using "Click Chemistry" strategy, and confirmed by NMR spectroscopy, IR and high resolution mass spectrometry (ESI-TOF). The products 15, 16a-d and 19a-d are novel compounds and will be evaluated for their cytotoxic activity against three tumor cell lines
Heteroaromatic annulation studies on 2-[bis(methylthio)methylene]- 1-methyl-3-oxoindole: synthesis of novel heterocyclo[b] fused indoles
No full textHeteroannulation of 2-[Bis(methylthio)methylene]-1-methyl-3-oxoindole with β- substituted β-lithioaminoacrylonitrile, malononitrile and guanidine has been reported to yield novel substituted pyrido[3,2-b]indoles and pyrimido[5,4-b]indole derivatives in varying yields
Heteroaromatic annulation studies on 2-[bis(methylthio)methylene]- 1-methyl-3-oxoindole: synthesis of novel heterocyclo[b] fused indoles
No full textHeteroannulation of 2-[Bis(methylthio)methylene]-1-methyl-3-oxoindole with β- substituted β-lithioaminoacrylonitrile, malononitrile and guanidine has been reported to yield novel substituted pyrido[3,2-b]indoles and pyrimido[5,4-b]indole derivatives in varying yields
Journal of Marketing Research : Vol. LIII, No. 2, April 2016
No full text1. Halo (Spillover) Effects in Social Media: Do Product Recalls of One Brand Hurt or Help Rival Brands?
Abhishek Borah and Gerard J. Tellis
2. Homogeneous Contracts for Heterogeneous Agents: Aligning Sales Force Composition and Compensation
3. The Influence of Serotonin Deficiency on Choice Deferral and the Compromise Effect
Marcel Lichters, Claudia Brunnlieb, Gideon Nave, Marko Sarstedt and Bodo Vogt
4. Can Sales Uncertainty Increase Firm Profits?
Niladri Syam, James D. Hess and Ying Yang
5. Advertising Effectiveness: The Moderating Effect of Firm Strategy
Leigh McAlister, Raji Srinivasan, Niket Jindal and Albert A. Cannella
6. Investigating How Word-of-Mouth Conversations About Brands Influence Purchase and Retransmission Intentions
Andrew M. Baker, Naveen Donthu and V. Kumar
7. Consumer Preferences for Annuity Attributes: Beyond Net Present Value
Suzanne B. Shu, Robert Zeithammer and John W. Payne
8. Lower Connectivity Is Better: The Effects of Network Structure on Redundancy of Ideas and Customer Innovativeness in Interdependent Ideation Tasks
Andrew T. Stephen, Peter Pal Zubcsek and Jacob Goldenberg
9. Community Participation and Consumer-to-Consumer Helping: Does Participation in Third Party–Hosted Communities Reduce One’s Likelihood of Helping?
Scott A. Thompson, Molan Kim and Keith Marion Smit
Prospective analysis of CNS tumor spectrum: A single centre experience in South India Corresponding Author
No full textAromatic and heteroaromatic annelation studies on 3-[bis(methylthio)methylene]-1-methyloxindole: synthesis of carbazoles and an efficient route to pyrido[2,3-b]indoles
No full textThe 3-[bis(methylthio)methylene]-1-methyloxindole (2) is shown to undergo cycloaromatization with allyl and methallyl magnesium chlorides to afford substituted carbazoles. A novel route to 2-substituted-3-cyano-4-methylthio/aminopyrido[2,3-b]indoles has been developed via heteroaromatic annelation of 2 with in situ generated 2-lithioamino-2-substituted acrylonitriles
Domino carbocationic cyclization of functionalized cyclopropyl ketones: facile one-pot access to peri- and angularly fused polycyclic aromatic and heteroaromatic frameworks
No full textConjugate adducts obtained by base-induced 1,4-addition-elimination of various aryl/heteroaryl acetonitriles with 1-(2-arylcyclopropyl)-3,3-(bismethylthio)-2-propen-1-ones have been shown to undergo facile acid-induced domino carbocationic rearrangement yielding a variety of substituted tricyclic aromatic and heteroaromatic frameworks in high yields in a one-pot operation. The methodology provides efficient, high-yield routes for synthesis of novel substituted dihydrophenalenes, dihydrobenzo[d,e]anthracene, cyclopenta[a]naphthalene, and fused heteroaromatics such as substituted 4,5-dihydrobenzo[c,d]indole, dihydronaphtho[1,8-b,c]thiophene, dihydroindeno[5,4-b]- and -[4,5-b]-thiophenes, cyclopenta[a]carbazole, and dihydrocyclopenta[e]indazol-3-one derivatives. The probable mechanism of this interesting domino process appears to involve stepwise or concomitant acid-induced ring opening and intramolecular cyclocondensation of cyclopropyl ketones to give benzo-fused arene (or heteroarene) intermediates bearing a reactive benzylic carbocation that is captured intramolecularly either by a preexisting aromatic (or heteroaromatic) ring or by a newly formed benzene ring to give either peri-fused or angularly fused products, respectively. Thus, the overall domino process entails formation of two C-C bonds, a substituted benzene ring along with a peri-fused cyclohexane or angularly fused cyclopentane ring in a single operation
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