838 research outputs found

    Biocontrol Potential of Novel Emerging Multiacting Bacterium Bacillus amyloliquefaciens NC6 against Brevicoryne brassicae in Brassica rapa ssp. Pekinensis

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    The emerging elicitor protein PeBA1, extracted from Bacillus amyloliquefaciens NC6, was tested against the cabbage aphid (Brevicoryne brassicae) for its biocontrol potential. Its effects on the survival, lifespan, immature development, adult reproductive performance, and pest–pathogen interaction were assessed using electrical penetration graphs (EPGs) against B. brassicae. Furthermore, the direct effects of PeBA1 with temperature and climate change in Brassica rapa ssp. Pekinensis plants were investigated by the characterization of active compounds in B. amyloliquefaciens with multi-acting entomopathogenic effects. Compared with controls, PeBA1 treatments decreased (second- and third-generation) B. brassicae population growth rates. In a host selection test, control plants were colonized faster by B. brassicae than PeBA1-treated B. rapa plants. The B. brassicae nymphal development was extended by PeBA1 concentrations. Likewise, fecundity was reduced in PeBA1-treated seedlings compared with control, with fewer offspring produced. The trichomes and wax production on PeBA1-treated leaves resulted in a hostile environment for B. brassicae. PeBA1 altered the surface structure of the leaves, reducing B. brassicae reproduction and preventing colonization. Systemic defensive processes also included the activation of pathways (JA, SA, and ET). Based on these findings against B. brassicae, integrated pest management and bio control with PeBA1 in the agroecosystem appears to be suitabl

    The Economic Ramifications of Strategic IT Security Information Sharing in the Financial Services Industry

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    We investigate the economic ramifications of strategic IT security information sharing among firms in the financial services industry. An IT security information sharing system can potentially minimize security breaches. However, although the Presidential Decision Directive/NSC-63 encouraged the establishment of such a system in the form of industry based information sharing and analysis centers (ISACs), it is injudicious to assume that firms will be willing to naively share their security information with their strategic competitors. We argue that without a proper mechanism some firms will try to put in minimum effort, potentially reducing the system’s reliability, and aim to answer the following research question: “What will it take for a financial services firm to willingly share its strategic information technology security information with its competitors through an ISAC?” We use the theory of mechanism design in economics to develop an adverse selection model to address the question

    Chalcophile Element Constraints on the Sulfur Content of the Martian Mantle

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    The sulfur content of the Martian mantle is critical to understanding volcanic volatiles supplied to the surface of Mars and possibly climate. In the absence of Martian mantle rocks, sulfur content of the mantle has been inferred from S contents of Martian meteorites or from sedimentary sulfate abundances. Estimates of the sulfur content of the Martian mantle vary from 390-2,000 ppm, all of which are higher than that of the terrestrial mantle (~250 ppm;). Residual sulfide in the Martian mantle controls the distribution of chalcophile elements during partial melting. In this study, we report new analyses of Martian meteorites, and use the incompatible behavior of As, Tl and Pb to infer the sulfide mode of the Martian mantle using a different set of assumptions than those of prior studies

    Tin Abundances Require that Chassignites Originated from Multiple Magmatic Bodies Distinct from Nakhlites

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    Meteorites from Mars lack field context but chemical and chronologic studies have revealed remarkable links between nakhlites and chassignites. A widely held consensus is that nakhlites and chassignites originated from a large, single differentiated flow or shallow intrusive [1-5]. An Ar-Ar study assumed multiple flows based on resolvable age differences between meteorites [6], but did not address the possibility of differential cooling in a large, shallowly emplaced intrusion [1]. REE abundances in pyroxenes from nakhlites and Chassigny led [7] to argue for derivation of these rocks from distinct magmas. Volatile abundances (F, Cl, OH) in chlorapatites indicated that the entire suite of nakhlites and chassignites experienced hydrothermal interaction with a single fluid supporting a single body origin [4]. The discovery of a new chassignite, NWA 8694, extended the Mg# range from 80-54, providing a closer link to nakhlites but revealed the petrological difficulty of fractionating a single body of liquid to yield a series of olivine cumulates with such a large Mg# range [8]. When mafic magmas are emplaced into the crust, crustal assimilation can impart distinct elemental signatures if the country rock has experienced sedimentary or hydrothermal processing [9]. In this work, we used Sn abundances of nakhlites and chassignites to show that these rocks were crystallized from distinct magma batches, providing vital contextual clues to their origin

    Minimization of Threshold-Current Dependence of Quantum Dot Laser Using InN

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    This paper focuses on the effect of threshold current density on different characteristics of quantum dot based laser. To investigate the effect, different characteristics have been analyzed using quantum dot as the active layer material of the laser structure. Performance improvement of quantum dot laser using InN has been achieved in terms of minimization of the threshold current dependence such as mirror loss, modal gain, turn-on delay and so forth. Numerical results have been analyzed considering the values of threshold current densities of GaN, AlN and InN based quantum dot lasers. Analytical results show that internal loss increases linearly with the increase of the threshold current density. However, other characteristics like mirror loss, modal gain, turn-on delay have nonlinear dependence on the threshold current density for any material used in the active layer. The threshold current density of InN quantum dot based laser is lower than that of other existing quantum dot based lasers. Analytical results ascertained that mirror loss has been increased a little bit. Conversely, internal loss and modal gain have been minimized considerably using InN based quantum dot in the active layer of the laser structure. In addition, turn-on delay time has been also minimized significantly

    Rethinking FS-ISAC: An IT Security Information Sharing Network Model for the Financial Services Sector

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    This study examines a critical incentive alignment issue facing FS-ISAC (the information sharing alliance in the financial services industry). Failure to encourage members to share their IT security-related information has seriously undermined the founding rationale of FS-ISAC. Our analysis shows that many information sharing alliances’ membership policies are plagued with the incentive misalignment issue and may result in a “free-riding” or “no information sharing” equilibrium. To address this issue, we propose a new information sharing membership policy that incorporates an insurance option and show that the proposed policy can align members’ incentives and lead to a socially optimal outcome. Moreover, when a transfer payment mechanism is implemented, all member firms will be better off joining the insurance network. These results are demonstrated in a simulation in which IT security breach losses are compared both with and without participating in the proposed information sharing insurance plan

    Osmium Isotope Systematics of Ureilites

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    The Os-187/Os-188 for twenty-two ureilite whole rock samples, including monomict, augite-bearing, and polymict lithologies, were examined in order to constrain the provenance and subsequent magmatic processing of the ureilite parent body (or bodies). The Re/Os ratios of most ureilites show evidence for a recent disturbance, probably related to Re mobility during weathering, and no meaningful chronological information can be extracted from the present data set. The ureilite Os-187/Os-188 ratios span a range from 0.11739 to 0.13018, with an average of 0.1258+/-0.0023 (1(sigma)), similar to typical carbonaceous chondrites, and distinct from ordinary or enstatite chondrites. The similar mean of Os-187/Os-188 measured for the ureilites and carbonaceous chondrites suggests that the ureilite parent body probably formed within the same region of the solar nebula as carbonaceous chondrites. From the narrow range of the 187Os/188Os distribution in ureilite meteorites it is further concluded that Re was not significantly fractionated from Os during planetary differentiation and was not lost along with the missing ureilitic melt component. The lack of large Re/Os fractionations requires that Re/Os partitioning was controlled by a metal phase, and thus metal had to be stable throughout the interval of magmatic processing on the ureilite parent body
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