2,759 research outputs found

    A typology for clients' multi-project environments

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    Construction management research and practice is dominated by a single project paradigm. This does not reflect the true nature of many construction clients who have large multi-project portfolios. Traditional single project management strategies are usually adopted for managing such portfolios - with limited success. The literature suggests that programmes, within portfolios, require different forms of management in order to optimize project delivery. In order to better understand these portfolios and thereby allow the exploration of new forms of management, a typology has been developed mapping out the various features of client's construction portfolios. The resultant typology provides a simple method for identifying the programme composition of a portfolio, highlighting the expected features of each programme type, and thereby directing management attention to the main aspects of each programme that can be optimized for efficiency. Six cases of client's construction project portfolios were studied using a highly structured, replication logic, case study methodology. A typology of clients' multi-project environments was developed and validated through literal and theoretical replication between cases. Three main types emerged as descriptive of programmes within client's construction portfolios: bounded programmes, target programmes and rolling programmes. The distinctive features of each type suggest that programme-specific approaches may be necessary for the successful delivery of projects within client's construction portfolios

    Phase transition in the Higgs model of scalar dyons

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    In the present paper we investigate the phase transition "Coulomb--confinement" in the Higgs model of abelian scalar dyons -- particles having both, electric ee and magnetic gg, charges. It is shown that by dual symmetry this theory is equivalent to scalar fields with the effective squared electric charge e^{*2}=e^2+g^2. But the Dirac relation distinguishes the electric and magnetic charges of dyons. The following phase transition couplings are obtained in the one--loop approximation: \alpha_{crit}=e^2_{crit}/4\pi\approx 0.19, \tilde\alpha_{crit}=g^2_{crit}/4\pi\approx 1.29 and \alpha^*_{crit}\approx 1.48.Comment: 16 pages, 2 figure

    Monopoles near the Planck Scale and Unification

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    Considering our (3+1)-dimensional space-time as, in some way, discrete or l attice with a parameter a=λPa=\lambda_P, where λP\lambda_P is the Planck length, we have investigated the additional contributions of lattice artifact monopoles to beta-functions of the renormalisation group equations for the running fine structure constants αi(μ)\alpha_i(\mu) (i=1,2,3 correspond to the U(1), SU(2) and SU(3) gauge groups of the Standard Model) in the Family Replicated Gauge Group Model (FRGGM) which is an extension of the Standard Model at high energies. It was shown that monopoles have NfamN_{fam} times smaller magnetic charge in FRGGM than in SM (NfamN_{fam} is the number of families in FRGGM). We have estimated al so the enlargement of a number of fermions in FRGGM leading to the suppression of the asymptotic freedom in the non-Abelian theory. We have shown that, in contrast to the case of AntiGUT when the FRGGM undergoes the breakdown at μ=μG1018\mu=\mu_G\sim 10^{18} GeV, we have the possibility of unification if the FRGGM-breakdown occurs at μG1014\mu_G\sim 10^{14} GeV. By numerical calculations we obtained an example of the unification of all gauge interactions (including gravity) at the scale μGUT1018.4\mu_{GUT}\approx 10^{18.4} GeV. We discussed the possibility of [SU(5)]3[SU(5)]^3 or [SO(10)]3[SO(10)]^3 (SUSY or not SUSY) unifications.Comment: 49 pages, 7 figure

    Clear Experimental Signature of Charge-Orbital density wave in Nd1x_{1-x}Ca1+x_{1+x}MnO4_{4}

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    Single Crystals of Nd1x_{1-x}Ca1+x_{1+x}MnO4_{4} have been prepared by the travelling floating-zone method, and possible evidence of a charge -orbital density wave in this material presented earlier [PRB68,092405 (2003)] using High Resolution Electron Microscopy [HRTEM] and Electron Diffraction [ED]. In the current note we present direct evidence of charge-orbital ordering in this material using heat capacity measurements. Our heat capacity measurements indicate a clear transition consistent with prior observation. We find two main transitions, one at temperature TH=310314T_{_H}=310-314 K, and other at TA=143T_{_A}=143 K. In addition, we may also conclude that there is a strong electron-phonon coupling in this material.Comment: 7 pages, 8 figure

    Phase transition in gauge theories, monopoles and the Multiple Point Principle

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    This review is devoted to the Multiple Point Principle (MPP), according to which several vacuum states with the same energy density exist in Nature. The MPP is implemented to the Standard Model (SM), Family replicated gauge group model (FRGGM) and phase transitions in gauge theories with/without monopoles. Lattice gauge theories are reviewed. The lattice results for critical coupling constants are compared with those of the Higgs Monopole Model (HMM), in which the lattice artifact monopoles are replaced by the point-like Higgs scalar particles with a magnetic charge. Considering our (3+1)-dimensional space-time as discrete, for example, as a lattice with a parameter a=\lambda_P, equal to the Planck length, we have investigated the additional contributions of monopoles to beta-functions of renormalization group equations in the FRGGM extended beyond the SM at high (the Planck scale) energies. We have reviewed that, in contrast to the Anti-grand unified theory (AGUT), there exists a possibility of unification of all gauge interactions (including gravity) near the Planck scale due to monopoles. The unifications [SU(5)]^3 and [SO(10)]^3 at the GUT-scale \sim 10^{18} GeV are briefly discussed.Comment: 100 pages, 25 figures, typos correcte

    Search for Heavy Leptons at Hadron Colliders

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    Four models are considered which contain heavy leptons beyond the three families of the standard model. Two are fourth-generation extensions of the standard model in which the right-handed heavy leptons are either isosinglets or in an isodoublet; the other two are motivated by the aspon model of CP violation. In all these models, the heavy neutrino can either be heavier than, or comparable in mass to, the charged lepton leading to the possibility that the charged lepton is very long-lived. Production cross section and signatures for the heavy leptons are computed for the SSC and LHC.Comment: 17 pages(8 figures are not included),TRI-PP-92-9

    Vacuum Stability Higgs Mass Bound Revisited with Implications for Extra Dimension Theories

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    We take the standard model to be an effective theory including higher dimensional operators suppressed by scale Λ\Lambda and re-examine the higgs mass bounds from the requirements of vacuum stability. Our results show that the effects of the higher dimensional operators on the higgs mass limits are significant. As an implication of our results, we study the vacuum stability higgs mass bounds in theories with extra dimensions.Comment: Latex, 14 pages, 1 figure. Added references. To appear in Phys. Rev.

    Influence of Light-trap Catches on Sex Ratio of Insects and Infestation in the Field of Cucurbitaceae

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    Insects are the curse for any type of crop and stored grains. Many techniques have been used so far to combat them. Pesticides are a major part of these techniques, but they also have negative aspects. In many European countries, the alternative techniques are, in practice, on low scale which is eco-friendly. Light-trap is one of them, which is used to study the effects on cucurbit insect pests in the present stud
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