Speckle Statistics in Adaptively Corrected Images

(abridged) Imaging observations are generally affected by a fluctuating background of speckles, a particular problem when detecting faint stellar companions at small angular separations. Knowing the distribution of the speckle intensities at a given location in the image plane is important for understanding the noise limits of companion detection. The speckle noise limit in a long-exposure image is characterized by the intensity variance and the speckle lifetime. In this paper we address the former quantity through the distribution function of speckle intensity. Previous theoretical work has predicted a form for this distribution function at a single location in the image plane. We developed a fast readout mode to take short exposures of stellar images corrected by adaptive optics at the ground-based UCO/Lick Observatory, with integration times of 5 ms and a time between successive frames of 14.5 ms ($\lambda=2.2$ $\mu$m). These observations temporally oversample and spatially Nyquist sample the observed speckle patterns. We show, for various locations in the image plane, the observed distribution of speckle intensities is consistent with the predicted form. Additionally, we demonstrate a method by which $I_c$ and $I_s$ can be mapped over the image plane. As the quantity $I_c$ is proportional to the PSF of the telescope free of random atmospheric aberrations, this method can be used for PSF calibration and reconstruction.Comment: 7 pages, 4 figures, ApJ accepte

Identifying the factors that influence innovation championing behaviour in construction support services organisations: a review of the role of middle management

W065 Organisation and Management of Construction Postgraduate Research: Paper ID: 542Innovation has been considered an important means by which organisations seek to achieve advantage over competition and for improving performance in today's highly competitive business environment. A number of factors have been identified as influencing innovation in project-based construction organisations. These include internal factors such as organisational culture, climate, leadership style and exogenous influences such as clients. Although research recognises how important it is for senior management to create an environment conducive to innovation, there is little understanding of how these internal and external factors interact to impact on innovativeness. This paper reviews relevant literature on innovation, organisational culture, organisational climate and leadership style while examining how they combine with external factors to promote innovation in construction support services organisations. The study particularly focuses on the role of key organisational actors with responsibility for developing a climate to facilitate innovation at the divisional or business unit level. The review reveals that efforts to develop a climate that promotes innovation championing behaviour among project managers will be influenced by the organizational culture, leadership style and the extent of external influence on project delivery. The study further reveals the importance of middle managers in promoting innovation. A methodology is presented for examining the role of this key managerial constituency and the ways in which they can enable or impede the innovation process.postprintThe 2010 World Congress of CIB on Building a Better World, University of Salford, Salford, U.K., 10-14 May 2010. In Proceedings: TG65 and W065 - Special Track. 18th CIB World Building Congress, 2010, p. 434-44

Managing knowledge workers' commitment in small construction professional firms

Construction professional services (CPS) rely heavily on knowledge workers as their main resources in delivering their services. One of the main concerns in managing these workers is the development and maintenance of organisational commitment. Smaller firms, with more informal human resource management systems and practices are more likely to face challenges in managing their knowledge workers’ commitment. Arguably, the intrinsic characteristics of the construction industry mean that this effort of managing knowledge workers’ commitment will require an appropriate management framework for its successful implementation. This research seeks to develop a framework for informing the management of knowledge workers in a way that fosters organisational commitment in small CPS firms. Interviews with the employers of small CPS firms were conducted to explore some of the important issues such as the strategies and challenges associated with effectively managing knowledge workers’ organisational commitment. The findings reveal that employers associate commitment with loyalty and high quality work. Many strategies are used to influence commitment such as performance-based compensation, close working relationship, training, employee involvement in decision making and two-way communication. Meanwhile, the provision of job security and career advancement were seen as the biggest challenges in managing knowledge workers’ commitment. Finally, we conclude with limitations and implications of the findings that provide directions for future research

Disorder-Induced Shift of Condensation Temperature for Dilute Trapped Bose Gases

We determine the leading shift of the Bose-Einstein condensation temperature for an ultracold dilute atomic gas in a harmonic trap due to weak disorder by treating both a Gaussian and a Lorentzian spatial correlation for the quenched disorder potential. Increasing the correlation length from values much smaller than the geometric mean of the trap scale and the mean particle distance to much larger values leads first to an increase of the positive shift to a maximum at this critical length scale and then to a decrease.Comment: Author information under http://www.theo-phys.uni-essen.de/tp/ags/pelster_di

Atomic Bose and Anderson glasses in optical lattices

An ultra cold atomic Bose gas in an optical lattice is shown to provide an ideal system for the controlled analysis of disordered Bose lattice gases. This goal may be easily achieved under the current experimental conditions, by introducing a pseudo-random potential created by a second additional lattice or, alternatively, by placing a speckle pattern on the main lattice. We show that for a non commensurable filling factor, in the strong interaction limit, a controlled growing of the disorder drives a dynamical transition from superfluid to Bose-glass phase. Similarly, in the weak interaction limit, a dynamical transition from superfluid to Anderson-glass phase may be observed. In both regimes, we show that even very low-intensity disorder-inducing lasers cause large modifications of the superfluid fraction of the system.Comment: 4 pages, 3 figures. Minor changes. To appear in Phys. Rev. Lett. (2003

Development of a Web-Based Human Resource Sourcing System for Labour Only Contracts

Nowadays in some areas of Nigeria, it has been noticed that the search for a satisfactory team of labourers (skilled and unskilled) or even the right amount of people to undertake the job has become a laborious activity. Therefore, there is need to build a two-way partnership system linking construction firms with the required skilled labour and vice versa. The aim of this research is to develop a web-based human resource sourcing system for labour only contracts. The study made use of a questionnaire instrument and developed a web-based interface for skilled labour sourcing. The questionnaire was distributed to fifty (50) construction professionals who were selected through a convenience sampling technique. The data collected was analyzed using SPSS v.21. The design of the system was done using hypertext markup language (HTML) for authoring web pages. The study revealed that contractors’ sourcing techniques for skilled labour on construction projects were mostly by referral from colleagues and workers from past projects. The study identified the major barriers in sourcing for skilled labour on construction projects as the unavailability of trained skilled labour. The study revealed that years of experience, wages charged and behavior of the worker were major criteria considered while sourcing for skilled labour on construction projects. In conclusion, the study developed a web based human resource sourcing system for labour only contracts that incorporated the needs of the skilled labour and requirement of construction firms. It was recommended that construction professionals and contractors need to harness the benefits of web-based technologies. In addition, there is need to increase the information and communication technology (ICT) trainings of workers in the construction industry so has to have a successful integration of ICT and the construction industry

Alginate inhibits iron absorption from ferrous gluconate in a randomized controlled trial and reduces iron uptake into Caco-2 cells

Previous in vitro results indicated that alginate beads might be a useful vehicle for food iron fortification. A human study was undertaken to test the hypothesis that alginate enhances iron absorption. A randomised, single blinded, cross-over trial was carried out in which iron absorption was measured from serum iron appearance after a test meal. Overnight-fasted volunteers (n=15) were given a test meal of 200g cola-flavoured jelly plus 21 mg iron as ferrous gluconate, either in alginate beads mixed into the jelly or in a capsule. Iron absorption was lower from the alginate beads than from ferrous gluconate (8.5% and 12.6% respectively, p=0.003). Sub-group B (n=9) consumed the test meals together with 600 mg calcium to determine whether alginate modified the inhibitory effect of calcium. Calcium reduced iron absorption from ferrous gluconate by 51%, from 11.5% to 5.6% (p=0.014), and from alginate beads by 37%, from 8.3% to 5.2% (p=0.009). In vitro studies using Caco-2 cells were designed to explore the reasons for the difference between the previous in vitro findings and the human study; confirmed the inhibitory effect of alginate. Beads similar to those used in the human study were subjected to simulated gastrointestinal digestion, with and without cola jelly, and the digestate applied to Caco-2 cells. Both alginate and cola jelly significantly reduced iron uptake into the cells, by 34% (p=0.009) and 35% (p=0.003) respectively. The combination of cola jelly and calcium produced a very low ferritin response, 16.5% (p<0.001) of that observed with ferrous gluconate alone. The results of these studies demonstrate that alginate beads are not a useful delivery system for soluble salts of iron for the purpose of food fortification

Intensity distribution for waves in disordered media: deviations from Rayleigh statistics

We study the intensity distribution function, P(I), for monochromatic waves propagating in quasi one-dimensional disordered medium, assuming that a point source and a point detector are embedded in the bulk of the medium. We find deviations from the Rayleigh statistics at moderately large I and a logarithmically-normal asymptotic behavior of P(I). When the radiation source and the detector are located close to the opposite edges of the sample (on a distance much less then the sample length), an intermediate regime with a stretched-exponential behavior of P(I) emerges.Comment: 4 pages Revtex, 3 figures included as eps file

Disordered ultracold atomic gases in optical lattices: A case study of Fermi-Bose mixtures

We present a review of properties of ultracold atomic Fermi-Bose mixtures in inhomogeneous and random optical lattices. In the strong interacting limit and at very low temperatures, fermions form, together with bosons or bosonic holes, {\it composite fermions}. Composite fermions behave as a spinless interacting Fermi gas, and in the presence of local disorder they interact via random couplings and feel effective random local potential. This opens a wide variety of possibilities of realizing various kinds of ultracold quantum disordered systems. In this paper we review these possibilities, discuss the accessible quantum disordered phases, and methods for their detection. The discussed quantum phases include Fermi glasses, quantum spin glasses, "dirty" superfluids, disordered metallic phases, and phases involving quantum percolation.Comment: 29 pages and 11 figure