Critical number of atoms in an attractive Bose-Einstein condensate on an optical plus harmonic traps

The stability of an attractive Bose-Einstein condensate on a joint one-dimensional optical lattice and an axially-symmetric harmonic trap is studied using the numerical solution of the time-dependent mean-field Gross-Pitaevskii equation and the critical number of atoms for a stable condensate is calculated. We also calculate this critical number of atoms in a double-well potential which is always greater than that in an axially-symmetric harmonic trap. The critical number of atoms in an optical trap can be made smaller or larger than the corresponding number in the absence of the optical trap by moving a node of the optical lattice potential along the axial direction of the harmonic trap. This variation of the critical number of atoms can be observed experimentally and compared with the present calculation.Comment: Latex with 7 eps figures, Accepted in Journal of Physics

Innovative procurement adoption for Industrialised Building System (IBS) projects

Industrialised Building System [IBS] is a new method that used prefabrication components in building construction as an alternative towards enhancing construction performance. The Construction Industry Development Board [CIDB] embraced the IBS method to enhance productivity and building quality, reduce wastage on site, increase occupational safety and health, and reduce overall cost of construction. Currently, most of the IBS project developments in Malaysia are still adopting traditional procurement system. How-ever, traditional procurement system has been criticised for its fragmented procedure to project delivery in terms of integration and collaboration of the project team. As a result of that problem, a number of issues have recently arisen such as reworks, time delay, rising costs, lack of communication and coordination, and wastages. The purpose of this research is to identify challenges of the current procurement system and to investigate the possibilities of implementing innovative type of procurement method for IBS im-plementation. A deductive research approach was adopted. Reviewing relevant literature before embarking into any academic re-search project is one way of exploring a known theory in a holistic manner. It also appears to be one of an essential feature to create a firm foundation for the research. Based on extensive literature reviews; this paper describes what are initiatives that have been taken from developed nations which are known as earlier IBS adopters and through the findings these experiences may shed some light on the type of procurement that have been adopted. This study was conducted among Grade 7 IBS contractors in Malaysia to gain further clarification on the immensity of the issues as well as assessing the research instrument. The findings from this study reveal that financial matters, lack of early involvement, lack of integration and coordination, knowledge and understanding, role and responsibility, risk liability, communication and information, attitude and relationship matters are challenges embedded in the existing procurement approach in adopting IBS. Suggestion on how innovative type of procurement method such as Separation of IBS from Main Contract, Partnering and Integrated Project Delivery [IPD] will be able to minimise the fragmentation gaps will be concluded

Angiographically proven hypothenar hammer syndrome in a school teacher

Hypothenar hammer syndrome (HSS) is a rare condition caused by thrombosis of the superficial palmar branch of the ulnar artery, known to occur in people who use the hypothenar or medial aspect of their hands literally as a hammer in a routine or habitual manner, leading to ischaemia of the hands. Certain occupational and recreational activities have been reported to predispose to this trauma-induced condition, however, there are no reports documenting this syndrome in a school teacher. Most studies have also been diagnosed on clinical and ultrasound imaging grounds. However, conventional upper limb angiography is considered the gold standard as of late, and it has been able to diagnose this condition more frequently, after exclusion of other risk factors such as connective tissue disease and congenital vascular malformations. We report a case of a teacher who presented with pain and weakness of his dominant hand, which has been angiographically proven to be due to ulnar artery occlusion at the palmar arch. This article can help explain a potentially debilitating condition that has never been reported before in a teacher, thus highlighting possible behavioural related occupational hazards that can be avoided

Degradation versus self-assembly of block copolymer micelles

The stability of micelles self-assembled from block copolymers can be altered by the degradation of the blocks. Slow degradation shifts the equilibrium size distribution of block copolymer micelles and change their properties. Quasi-equilibrium scaling theory shows that the degradation of hydrophobic blocks in the core of micelles destabilize the micelles reducing their size, while the degradation of hydrophilic blocks forming coronas of micelles favors larger micelles and may, at certain conditions, induce the formation of micelles from individual chains.Comment: Published in Langmuir http://pubs.acs.org/doi/pdf/10.1021/la204625

Tunable tunneling: An application of stationary states of Bose-Einstein condensates in traps of finite depth

The fundamental question of how Bose-Einstein condensates tunnel into a barrier is addressed. The cubic nonlinear Schrodinger equation with a finite square well potential, which models a Bose-Einstein condensate in a quasi-one-dimensional trap of finite depth, is solved for the complete set of localized and partially localized stationary states, which the former evolve into when the nonlinearity is increased. An immediate application of these different solution types is tunable tunneling. Magnetically tunable Feshbach resonances can change the scattering length of certain Bose-condensed atoms, such as $^{85}$Rb, by several orders of magnitude, including the sign, and thereby also change the mean field nonlinearity term of the equation and the tunneling of the wavefunction. We find both linear-type localized solutions and uniquely nonlinear partially localized solutions where the tails of the wavefunction become nonzero at infinity when the nonlinearity increases. The tunneling of the wavefunction into the non-classical regime and thus its localization therefore becomes an external experimentally controllable parameter.Comment: 11 pages, 5 figure

Macroscopic superposition states of ultracold bosons in a double-well potential

We present a thorough description of the physical regimes for ultracold bosons in double wells, with special attention paid to macroscopic superpositions (MSs). We use a generalization of the Lipkin-Meshkov-Glick Hamiltonian of up to eight single particle modes to study these MSs, solving the Hamiltonian with a combination of numerical exact diagonalization and high-order perturbation theory. The MS is between left and right potential wells; the extreme case with all atoms simultaneously located in both wells and in only two modes is the famous NOON state, but our approach encompasses much more general MSs. Use of more single particle modes brings dimensionality into the problem, allows us to set hard limits on the use of the original two-mode LMG model commonly treated in the literature, and also introduces a new mixed Josephson-Fock regime. Higher modes introduce angular degrees of freedom and MS states with different angular properties.Comment: 15 pages, 8 figures, 1 table. Mini-review prepared for the special issue of Frontiers of Physics "Recent Progresses on Quantum Dynamics of Ultracold Atoms and Future Quantum Technologies", edited by Profs. Lee, Ueda, and Drummon

Influenza virus infection of newborn rats: Virulence of recombinant strains prepared from a cold-adapted, attenuated parent

Infant rats were infected with one of a series of influenza A viruses. The growth of viruses in the turbinates or lungs, and the ability of virus infection to potentiate a subsequent bacterial infection by Haemophilus influenzae (HIb), were measured. The three virus strains known to be virulent for man grew to relatively high titres-of 10 5.0 –10 6.8 EBID 50 /ml in the turbinates of infant rats at 48 hours post-infection, and virus infection enhanced subsequent systemic infection following intranasal inoculation of rats with HIb. In contrast, influenza virus A/Ann Arbor/6/60—P17 and the three recombinant viruses prepared from this strain, all of which are attenuated for man, replicated to significantly lower titres of 10 2.6 –10 4.1 EBID 50 /ml in infant rats turbinates, and failed to promote systemic infection by HIb to the same degree. The results, together with those of previous studies, suggest that the behaviour of influenza viruses in infant rats may be an indication for virus virulence for man, and thus provide a test which could facilitate the development of live, attenuated virus vaccines.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41687/1/705_2005_Article_BF01318055.pd

Structural and Functional Analysis of Validoxylamine A 7′-phosphate Synthase ValL Involved in Validamycin A Biosynthesis

Validamycin A (Val-A) is an effective antifungal agent widely used in Asian countries as crop protectant. Validoxylamine A, the core structure and intermediate of Val-A, consists of two C7-cyclitol units connected by a rare C-N bond. In the Val-A biosynthetic gene cluster in Streptomyces hygroscopicus 5008, the ORF valL was initially annotated as a validoxylamine A 7′-phosphate(V7P) synthase, whose encoded 497-aa protein shows high similarity with trehalose 6-phosphate(T6P) synthase. Gene inactivation of valL abolished both validoxylamine A and validamycin A productivity, and complementation with a cloned valL recovered 10% production of the wild-type in the mutant, indicating the involvement of ValL in validoxylamine A biosynthesis. Also we determined the structures of ValL and ValL/trehalose complex. The structural data indicates that ValL adopts the typical fold of GT-B protein family, featuring two Rossmann-fold domains and an active site at domain junction. The residues in the active site are arranged in a manner homologous to that of Escherichia coli (E.coli) T6P synthase OtsA. However, a significant discrepancy is found in the active-site loop region. Also noticeable structural variance is found around the active site entrance in the apo ValL structure while the region takes an ordered configuration upon binding of product analog trehalose. Furthermore, the modeling of V7P in the active site of ValL suggests that ValL might have a similar SNi-like mechanism as OtsA

Self-Organizing Networks in Complex Infrastructure Projects

While significant importance is given to establishing formal organizational and contractual hierarchies, existing project management techniques neglect the management of self-organizing networks in large-infrastructure projects. We offer a case-specific illustration of self-organization using network theory as an investigative lens. The findings have shown that these networks exhibit a high degree of sparseness, short path lengths, and clustering in dense “functional” communities around highly connected actors, thus demonstrating the small-world topology observed in diverse real-world self-organized networks. The study underlines the need for these non-contractual functions and roles to be identified and sponsored, allowing the self-organizing network the space and capacity to evolve