A Risk Analysis of Construction Projects Delay Factors in the United Kingdom

Project time overruns is a recurring challenge in the construction industry. This paper mainly identified the causes of construction project delays, analysed the probability and impact of occurrence, and ranked the risk factors. The identified factors are categorised into Client, Consultant, Contractor, and External related factors. To achieve the research objective, the identified delay factors were part of a questionnaire survey; and responses were yielded from building construction experts in the United Kingdom. The relative importance index (RII) method was applied to prioritise the probability and impact of project delay factors and determine the risk level. In the four categories, delay in decision-making and order issuance by the client, variation and changes in design, delay in the approval of drawings, and delay in design preparation and late revision of designs are some of the identified top-ranking risks. In addition, the delay in providing utilities, construction mistakes, defective works and rework, adverse weather conditions, and delays or issues regarding permissions and statutory approvals are among the top-ranking risks. This research is expected to significantly contribute to and improve the understanding and perception of the risks posed by the various delay factors, especially in the building construction industry

Leptogenesis from Soft Supersymmetry Breaking (Soft Leptogenesis)

Soft leptogenesis is a scenario in which the cosmic baryon asymmetry is produced from a lepton asymmetry generated in the decays of heavy sneutrinos (the partners of the singlet neutrinos of the seesaw) and where the relevant sources of CP violation are the complex phases of soft supersymmetry-breaking terms. We explain the motivations for soft leptogenesis, and review its basic ingredients: the different CP-violating contributions, the crucial role played by thermal corrections, and the enhancement of the efficiency from lepton flavour effects. We also discuss the high temperature regime $T > 10^7$ GeV in which the cosmic baryon asymmetry originates from an initial asymmetry of an anomalous $R$-charge, and soft leptogenesis reembodies in $R$-genesis.Comment: References updated. Some minor corrections to match the published versio

The scaling properties of exchange and correlation holes of the valence shell of second row atoms

We study the exchange and correlation hole of the valence shell of second row atoms using variational Monte Carlo techniques, especially correlated estimates, and norm-conserving pseudopotentials. The well-known scaling of the valence shell provides a tool to probe the behavior of exchange and correlation as a functional of the density and thus test models of density functional theory. The exchange hole shows an interesting competition between two scaling forms -- one caused by self-interaction and another that is approximately invariant under particle number, related to the known invariance of exchange under uniform scaling to high density and constant particle number. The correlation hole shows a scaling trend that is marked by the finite size of the atom relative to the radius of the hole. Both trends are well captured in the main by the Perdew-Burke-Ernzerhof generalized-gradient approximation model for the exchange-correlation hole and energy.Comment: 18 pages, 8 figure

Model studies of oxygen-intercalated graphite

The possibility of intercalating oxygen to reduce the conductivity of graphite has been investigated by modified intermediate neglect of differential overlap 3 and tight-binding methods. The cluster calculations suggest that the most stable position for the oxygen atom is 1.25 A above a carbon-carbon bond. The tight-binding band calculation predicts the stage-I intercalated graphite to be a zero-indirect-gap semiconductor. Higher-stage intercalated graphite is expected to have a finite insulating gap whose value is governed by the carbon-oxygen interaction