618 research outputs found

    IS Project Risks as Emergent Phenomena: Towards a Model of Risk Escalation and its Management

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    While the number of substantive investments in IS projects continues to grow, the number of failing projects also continues to increase at an alarming rate. Both the academic and industry literature suggests that inadequate attention to risk and its management continues to be a key factor in project failure. The typical approach taken is to identify and map potential risks, to act as a planning and diagnostic tool, and to prepare a contingency plan has been a factorbased approach. While it remains a valuable tool for mapping anticipated risks the factorbased approach is less effective when viewing project risks as emergent phenomena that unfold during the course of the project, and require ongoing attention and risk management. Informed by a case study of a failing university IS development project, this paper focuses on the phenomenon of risk escalation. The case findings suggest that rather than being defined ahead of the project, some project risks may emerge during the project as a consequence of escalation factors that were both antecedent to and a consequence of actual risk management decisions. The article concludes with suggestions as to how project managers can better man-age the emergent rather than static nature of risk phenomena

    Predictions for B→KγγB \to K \gamma \gamma decays

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    We present a phenomenological study of the rare double radiative decay B→KγγB\to K \gamma\gamma in the Standard Model (SM) and beyond. Using the operator product expansion (OPE) technique, we estimate the short-distance (SD) contribution to the decay amplitude in a region of the phase space which is around the point where all decay products have energy ∼mb/3\sim m_b/3 in the rest frame of the BB-meson. At lowest order in 1/Q, where QQ is of order mbm_b, the B→KγγB\to K \gamma\gamma matrix element is then expressed in terms of the usual B→KB\to K form factors known from semileptonic rare decays. The integrated SD branching ratio in the SM in the OPE region turns out to be ΔB(B→Kγγ)SMOPE≃1×10−9\Delta {\cal{B}}(B \to K \gamma \gamma)_{SM}^{OPE} \simeq 1 \times 10^{-9}. We work out the di-photon invariant mass distribution with and without the resonant background through B→K{ηc,χc0}→KγγB\to K \{\eta_c,\chi_{c0}\}\to K\gamma \gamma. In the SM, the resonance contribution is dominant in the region of phase space where the OPE is valid. The present experimental upper limit on Bs→τ+τ−B_s \to \tau^+ \tau^- decays, which constrains the scalar/pseudoscalar Four-Fermi operators with τ+τ−\tau^+ \tau^-, leaves considerable room for new physics in the one-particle-irreducible contribution to B→KγγB\to K \gamma \gamma decays. In this case, we find that the SD B→KγγB\to K \gamma \gamma branching ratio can be enhanced by one order of magnitude with respect to its SM value and the SD contribution can lie outside of the resonance peaks.Comment: 17 pages, 4 figures; Note added on Schouten identity and 2 references added; v4: typos in Eqs (8), (44) and erroneous statement on mixing before Eq (44) fixed. All results and conclusions unchange

    Topological Superfluid in one-dimensional Ultracold Atomic System with Spin-Orbit Coupling

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    We propose a one-dimensional Hamiltonian H1DH_{1D} which supports Majorana fermions when dx2−y2d_{x^{2}-y^{2}}-wave superfluid appears in the ultracold atomic system and obtain the phase-separation diagrams both for the time-reversal-invariant case and time-reversal-symmetry-breaking case. From the phase-separation diagrams, we find that the single Majorana fermions exist in the topological superfluid region, and we can reach this region by tuning the chemical potential μ\mu and spin-orbit coupling αR\alpha_{R}. Importantly, the spin-orbit coupling has realized in ultracold atoms by the recent experimental achievement of synthetic gauge field, therefore, our one-dimensional ultra-cold atomic system described by H1DH_{1D} is a promising platform to find the mysterious Majorana fermions.Comment: 5 papers, 2 figure

    T-functions revisited: New criteria for bijectivity/transitivity

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    The paper presents new criteria for bijectivity/transitivity of T-functions and fast knapsack-like algorithm of evaluation of a T-function. Our approach is based on non-Archimedean ergodic theory: Both the criteria and algorithm use van der Put series to represent 1-Lipschitz pp-adic functions and to study measure-preservation/ergodicity of these

    miR-23~27~24 clusters control effector T cell differentiation and function

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    Coordinated repression of gene expression by evolutionarily conserved microRNA (miRNA) clusters and paralogs ensures that miRNAs efficiently exert their biological impact. Combining both loss- and gain-of-function genetic approaches, we show that the miR-23~27~24 clusters regulate multiple aspects of T cell biology, particularly helper T (Th) 2 immunity. Low expression of this miRNA family confers proper effector T cell function at both physiological and pathological settings. Further studies in T cells with exaggerated regulation by individual members of the miR-23~27~24 clusters revealed that miR-24 and miR-27 collaboratively limit Th2 responses through targeting IL-4 and GATA3 in both direct and indirect manners. Intriguingly, although overexpression of the entire miR-23 cluster also negatively impacts other Th lineages, enforced expression of miR-24, in contrast to miR-23 and miR-27, actually promotes the differentiation of Th1, Th17, and induced regulatory T cells, implying that under certain conditions, miRNA families can fine tune the biological effects of their regulation by having individual members antagonize rather than cooperate with each other. Together, our results identify a miRNA family with important immunological roles and suggest that tight regulation of miR-23~27~24 clusters in T cells is required to maintain optimal effector function and to prevent aberrant immune responses

    How Does Pubertal Development Impact Caregiver-Adolescent Communication About Sex in Rural, African American Families? An Examination of Mediation Effects

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    This study examined the relationship between pubertal development and type of caregiver-adolescent communication about sex (CACS) among 441 African American caregivers participating in an intervention trial in rural North Carolina. We assessed CACS about general sexual health topics and positive aspects of sexuality. Caregivers’ attitudes and self-efficacy for CACS, and open communication style were examined as potential mediators. Caregivers engaged in low levels of communication about sex regardless of type. Among caregivers of males, pubertal development was associated with greater communication about general sexual health, which was mediated by self-efficacy for CACS. Among caregivers of females, pubertal development was associated with less communication about general and positive sexual health topics; however, there were no mediating factors. These findings highlight the predictors of CACS among young men and women after pubertal onset. Age appropriate, practical guidance for initiating CACS may be critical for ensuring caregiver talk about sex

    High-Energy Aspects of Solar Flares: Overview of the Volume

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    In this introductory chapter, we provide a brief summary of the successes and remaining challenges in understanding the solar flare phenomenon and its attendant implications for particle acceleration mechanisms in astrophysical plasmas. We also provide a brief overview of the contents of the other chapters in this volume, with particular reference to the well-observed flare of 2002 July 23Comment: This is the introductory article for a monograph on the physics of solar flares, inspired by RHESSI observations. The individual articles are to appear in Space Science Reviews (2011

    Asymptotology of Chemical Reaction Networks

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    The concept of the limiting step is extended to the asymptotology of multiscale reaction networks. Complete theory for linear networks with well separated reaction rate constants is developed. We present algorithms for explicit approximations of eigenvalues and eigenvectors of kinetic matrix. Accuracy of estimates is proven. Performance of the algorithms is demonstrated on simple examples. Application of algorithms to nonlinear systems is discussed.Comment: 23 pages, 8 figures, 84 refs, Corrected Journal Versio

    Understanding the Relationship between Religiosity and Caregiver–Adolescent Communication About Sex within African-American Families

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    Caregiver–adolescent communication about sex plays a critical role in the sexual socialization of youth. Many caregivers, however, do not engage their youth in such conversations, potentially placing them at risk for negative sexual health outcomes. Lack of caregiver–adolescent communication about sex may be particularly harmful for rural African American youth, as they often report early sex initiation and are disproportionately impacted by STIs. Moreover, sexual communication may be particularly challenging for families with strong religious backgrounds, potentially affecting the occurrence and breadth of topics covered during communication. Study aims were to: determine whether there was a relationship between caregiver religiosity and type of topics covered during communication about sex (e.g., general sexual health vs. positive aspects of sexuality) among 435 caregivers of early adolescent, African American youth; and if so, identify factors that might explain how religiosity affects communication about sex. Results indicated that caregiver religiosity was positively associated with communication about general, but not positive aspects of sexuality for caregivers of males. Attitudes towards communication about sex and open communication style mediated the relationship. There was no association between religiosity and communication about sex for caregivers of females. The findings from this study could provide a base to better understand and support the sexual socialization process within religious, African American families
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